rev 7249 : 8061748: Remove check_ct_logs_at_safepoint()
Summary: Remove unused function and related closure class
Reviewed-by:
Contributed-by: kim.barrett@oracle.com

   1 /*
   2  * Copyright (c) 2001, 2014, 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 #if !defined(__clang_major__) && defined(__GNUC__)
  26 // FIXME, formats have issues.  Disable this macro definition, compile, and study warnings for more information.
  27 #define ATTRIBUTE_PRINTF(x,y)
  28 #endif
  29 
  30 #include "precompiled.hpp"
  31 #include "classfile/metadataOnStackMark.hpp"
  32 #include "classfile/stringTable.hpp"
  33 #include "code/codeCache.hpp"
  34 #include "code/icBuffer.hpp"
  35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  43 #include "gc_implementation/g1/g1EvacFailure.hpp"
  44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  45 #include "gc_implementation/g1/g1Log.hpp"
  46 #include "gc_implementation/g1/g1MarkSweep.hpp"
  47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
  49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
  50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  51 #include "gc_implementation/g1/g1StringDedup.hpp"
  52 #include "gc_implementation/g1/g1YCTypes.hpp"
  53 #include "gc_implementation/g1/heapRegion.inline.hpp"
  54 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  55 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
  56 #include "gc_implementation/g1/vm_operations_g1.hpp"
  57 #include "gc_implementation/shared/gcHeapSummary.hpp"
  58 #include "gc_implementation/shared/gcTimer.hpp"
  59 #include "gc_implementation/shared/gcTrace.hpp"
  60 #include "gc_implementation/shared/gcTraceTime.hpp"
  61 #include "gc_implementation/shared/isGCActiveMark.hpp"
  62 #include "memory/allocation.hpp"
  63 #include "memory/gcLocker.inline.hpp"
  64 #include "memory/generationSpec.hpp"
  65 #include "memory/iterator.hpp"
  66 #include "memory/referenceProcessor.hpp"
  67 #include "oops/oop.inline.hpp"
  68 #include "oops/oop.pcgc.inline.hpp"
  69 #include "runtime/atomic.inline.hpp"
  70 #include "runtime/orderAccess.inline.hpp"
  71 #include "runtime/vmThread.hpp"
  72 #include "utilities/globalDefinitions.hpp"
  73 
  74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  75 
  76 // turn it on so that the contents of the young list (scan-only /
  77 // to-be-collected) are printed at "strategic" points before / during
  78 // / after the collection --- this is useful for debugging
  79 #define YOUNG_LIST_VERBOSE 0
  80 // CURRENT STATUS
  81 // This file is under construction.  Search for "FIXME".
  82 
  83 // INVARIANTS/NOTES
  84 //
  85 // All allocation activity covered by the G1CollectedHeap interface is
  86 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  87 // and allocate_new_tlab, which are the "entry" points to the
  88 // allocation code from the rest of the JVM.  (Note that this does not
  89 // apply to TLAB allocation, which is not part of this interface: it
  90 // is done by clients of this interface.)
  91 
  92 // Notes on implementation of parallelism in different tasks.
  93 //
  94 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism.
  95 // The number of GC workers is passed to heap_region_par_iterate().
  96 // It does use run_task() which sets _n_workers in the task.
  97 // G1ParTask executes g1_process_roots() ->
  98 // SharedHeap::process_roots() which calls eventually to
  99 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
 100 // SequentialSubTasksDone.  SharedHeap::process_roots() also
 101 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
 102 //
 103 
 104 // Local to this file.
 105 
 106 class RefineCardTableEntryClosure: public CardTableEntryClosure {
 107   bool _concurrent;
 108 public:
 109   RefineCardTableEntryClosure() : _concurrent(true) { }
 110 
 111   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 112     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 113     // This path is executed by the concurrent refine or mutator threads,
 114     // concurrently, and so we do not care if card_ptr contains references
 115     // that point into the collection set.
 116     assert(!oops_into_cset, "should be");
 117 
 118     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 119       // Caller will actually yield.
 120       return false;
 121     }
 122     // Otherwise, we finished successfully; return true.
 123     return true;
 124   }
 125 
 126   void set_concurrent(bool b) { _concurrent = b; }
 127 };
 128 
 129 



































 130 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 131  private:
 132   size_t _num_processed;
 133 
 134  public:
 135   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 136 
 137   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 138     *card_ptr = CardTableModRefBS::dirty_card_val();
 139     _num_processed++;
 140     return true;
 141   }
 142 
 143   size_t num_processed() const { return _num_processed; }
 144 };
 145 
 146 YoungList::YoungList(G1CollectedHeap* g1h) :
 147     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 148     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 149   guarantee(check_list_empty(false), "just making sure...");
 150 }
 151 
 152 void YoungList::push_region(HeapRegion *hr) {
 153   assert(!hr->is_young(), "should not already be young");
 154   assert(hr->get_next_young_region() == NULL, "cause it should!");
 155 
 156   hr->set_next_young_region(_head);
 157   _head = hr;
 158 
 159   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 160   ++_length;
 161 }
 162 
 163 void YoungList::add_survivor_region(HeapRegion* hr) {
 164   assert(hr->is_survivor(), "should be flagged as survivor region");
 165   assert(hr->get_next_young_region() == NULL, "cause it should!");
 166 
 167   hr->set_next_young_region(_survivor_head);
 168   if (_survivor_head == NULL) {
 169     _survivor_tail = hr;
 170   }
 171   _survivor_head = hr;
 172   ++_survivor_length;
 173 }
 174 
 175 void YoungList::empty_list(HeapRegion* list) {
 176   while (list != NULL) {
 177     HeapRegion* next = list->get_next_young_region();
 178     list->set_next_young_region(NULL);
 179     list->uninstall_surv_rate_group();
 180     // This is called before a Full GC and all the non-empty /
 181     // non-humongous regions at the end of the Full GC will end up as
 182     // old anyway.
 183     list->set_old();
 184     list = next;
 185   }
 186 }
 187 
 188 void YoungList::empty_list() {
 189   assert(check_list_well_formed(), "young list should be well formed");
 190 
 191   empty_list(_head);
 192   _head = NULL;
 193   _length = 0;
 194 
 195   empty_list(_survivor_head);
 196   _survivor_head = NULL;
 197   _survivor_tail = NULL;
 198   _survivor_length = 0;
 199 
 200   _last_sampled_rs_lengths = 0;
 201 
 202   assert(check_list_empty(false), "just making sure...");
 203 }
 204 
 205 bool YoungList::check_list_well_formed() {
 206   bool ret = true;
 207 
 208   uint length = 0;
 209   HeapRegion* curr = _head;
 210   HeapRegion* last = NULL;
 211   while (curr != NULL) {
 212     if (!curr->is_young()) {
 213       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 214                              "incorrectly tagged (y: %d, surv: %d)",
 215                              curr->bottom(), curr->end(),
 216                              curr->is_young(), curr->is_survivor());
 217       ret = false;
 218     }
 219     ++length;
 220     last = curr;
 221     curr = curr->get_next_young_region();
 222   }
 223   ret = ret && (length == _length);
 224 
 225   if (!ret) {
 226     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 227     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 228                            length, _length);
 229   }
 230 
 231   return ret;
 232 }
 233 
 234 bool YoungList::check_list_empty(bool check_sample) {
 235   bool ret = true;
 236 
 237   if (_length != 0) {
 238     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 239                   _length);
 240     ret = false;
 241   }
 242   if (check_sample && _last_sampled_rs_lengths != 0) {
 243     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 244     ret = false;
 245   }
 246   if (_head != NULL) {
 247     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 248     ret = false;
 249   }
 250   if (!ret) {
 251     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 252   }
 253 
 254   return ret;
 255 }
 256 
 257 void
 258 YoungList::rs_length_sampling_init() {
 259   _sampled_rs_lengths = 0;
 260   _curr               = _head;
 261 }
 262 
 263 bool
 264 YoungList::rs_length_sampling_more() {
 265   return _curr != NULL;
 266 }
 267 
 268 void
 269 YoungList::rs_length_sampling_next() {
 270   assert( _curr != NULL, "invariant" );
 271   size_t rs_length = _curr->rem_set()->occupied();
 272 
 273   _sampled_rs_lengths += rs_length;
 274 
 275   // The current region may not yet have been added to the
 276   // incremental collection set (it gets added when it is
 277   // retired as the current allocation region).
 278   if (_curr->in_collection_set()) {
 279     // Update the collection set policy information for this region
 280     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 281   }
 282 
 283   _curr = _curr->get_next_young_region();
 284   if (_curr == NULL) {
 285     _last_sampled_rs_lengths = _sampled_rs_lengths;
 286     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 287   }
 288 }
 289 
 290 void
 291 YoungList::reset_auxilary_lists() {
 292   guarantee( is_empty(), "young list should be empty" );
 293   assert(check_list_well_formed(), "young list should be well formed");
 294 
 295   // Add survivor regions to SurvRateGroup.
 296   _g1h->g1_policy()->note_start_adding_survivor_regions();
 297   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 298 
 299   int young_index_in_cset = 0;
 300   for (HeapRegion* curr = _survivor_head;
 301        curr != NULL;
 302        curr = curr->get_next_young_region()) {
 303     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 304 
 305     // The region is a non-empty survivor so let's add it to
 306     // the incremental collection set for the next evacuation
 307     // pause.
 308     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 309     young_index_in_cset += 1;
 310   }
 311   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 312   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 313 
 314   _head   = _survivor_head;
 315   _length = _survivor_length;
 316   if (_survivor_head != NULL) {
 317     assert(_survivor_tail != NULL, "cause it shouldn't be");
 318     assert(_survivor_length > 0, "invariant");
 319     _survivor_tail->set_next_young_region(NULL);
 320   }
 321 
 322   // Don't clear the survivor list handles until the start of
 323   // the next evacuation pause - we need it in order to re-tag
 324   // the survivor regions from this evacuation pause as 'young'
 325   // at the start of the next.
 326 
 327   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 328 
 329   assert(check_list_well_formed(), "young list should be well formed");
 330 }
 331 
 332 void YoungList::print() {
 333   HeapRegion* lists[] = {_head,   _survivor_head};
 334   const char* names[] = {"YOUNG", "SURVIVOR"};
 335 
 336   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 337     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 338     HeapRegion *curr = lists[list];
 339     if (curr == NULL)
 340       gclog_or_tty->print_cr("  empty");
 341     while (curr != NULL) {
 342       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
 343                              HR_FORMAT_PARAMS(curr),
 344                              curr->prev_top_at_mark_start(),
 345                              curr->next_top_at_mark_start(),
 346                              curr->age_in_surv_rate_group_cond());
 347       curr = curr->get_next_young_region();
 348     }
 349   }
 350 
 351   gclog_or_tty->cr();
 352 }
 353 
 354 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 355   OtherRegionsTable::invalidate(start_idx, num_regions);
 356 }
 357 
 358 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 359   // The from card cache is not the memory that is actually committed. So we cannot
 360   // take advantage of the zero_filled parameter.
 361   reset_from_card_cache(start_idx, num_regions);
 362 }
 363 
 364 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 365 {
 366   // Claim the right to put the region on the dirty cards region list
 367   // by installing a self pointer.
 368   HeapRegion* next = hr->get_next_dirty_cards_region();
 369   if (next == NULL) {
 370     HeapRegion* res = (HeapRegion*)
 371       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 372                           NULL);
 373     if (res == NULL) {
 374       HeapRegion* head;
 375       do {
 376         // Put the region to the dirty cards region list.
 377         head = _dirty_cards_region_list;
 378         next = (HeapRegion*)
 379           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 380         if (next == head) {
 381           assert(hr->get_next_dirty_cards_region() == hr,
 382                  "hr->get_next_dirty_cards_region() != hr");
 383           if (next == NULL) {
 384             // The last region in the list points to itself.
 385             hr->set_next_dirty_cards_region(hr);
 386           } else {
 387             hr->set_next_dirty_cards_region(next);
 388           }
 389         }
 390       } while (next != head);
 391     }
 392   }
 393 }
 394 
 395 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 396 {
 397   HeapRegion* head;
 398   HeapRegion* hr;
 399   do {
 400     head = _dirty_cards_region_list;
 401     if (head == NULL) {
 402       return NULL;
 403     }
 404     HeapRegion* new_head = head->get_next_dirty_cards_region();
 405     if (head == new_head) {
 406       // The last region.
 407       new_head = NULL;
 408     }
 409     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 410                                           head);
 411   } while (hr != head);
 412   assert(hr != NULL, "invariant");
 413   hr->set_next_dirty_cards_region(NULL);
 414   return hr;
 415 }
 416 
 417 #ifdef ASSERT
 418 // A region is added to the collection set as it is retired
 419 // so an address p can point to a region which will be in the
 420 // collection set but has not yet been retired.  This method
 421 // therefore is only accurate during a GC pause after all
 422 // regions have been retired.  It is used for debugging
 423 // to check if an nmethod has references to objects that can
 424 // be move during a partial collection.  Though it can be
 425 // inaccurate, it is sufficient for G1 because the conservative
 426 // implementation of is_scavengable() for G1 will indicate that
 427 // all nmethods must be scanned during a partial collection.
 428 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 429   if (p == NULL) {
 430     return false;
 431   }
 432   return heap_region_containing(p)->in_collection_set();
 433 }
 434 #endif
 435 
 436 // Returns true if the reference points to an object that
 437 // can move in an incremental collection.
 438 bool G1CollectedHeap::is_scavengable(const void* p) {
 439   HeapRegion* hr = heap_region_containing(p);
 440   return !hr->is_humongous();










































 441 }
 442 
 443 // Private class members.
 444 
 445 G1CollectedHeap* G1CollectedHeap::_g1h;
 446 
 447 // Private methods.
 448 
 449 HeapRegion*
 450 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 451   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 452   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 453     if (!_secondary_free_list.is_empty()) {
 454       if (G1ConcRegionFreeingVerbose) {
 455         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 456                                "secondary_free_list has %u entries",
 457                                _secondary_free_list.length());
 458       }
 459       // It looks as if there are free regions available on the
 460       // secondary_free_list. Let's move them to the free_list and try
 461       // again to allocate from it.
 462       append_secondary_free_list();
 463 
 464       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 465              "empty we should have moved at least one entry to the free_list");
 466       HeapRegion* res = _hrm.allocate_free_region(is_old);
 467       if (G1ConcRegionFreeingVerbose) {
 468         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 469                                "allocated "HR_FORMAT" from secondary_free_list",
 470                                HR_FORMAT_PARAMS(res));
 471       }
 472       return res;
 473     }
 474 
 475     // Wait here until we get notified either when (a) there are no
 476     // more free regions coming or (b) some regions have been moved on
 477     // the secondary_free_list.
 478     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 479   }
 480 
 481   if (G1ConcRegionFreeingVerbose) {
 482     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 483                            "could not allocate from secondary_free_list");
 484   }
 485   return NULL;
 486 }
 487 
 488 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 489   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 490          "the only time we use this to allocate a humongous region is "
 491          "when we are allocating a single humongous region");
 492 
 493   HeapRegion* res;
 494   if (G1StressConcRegionFreeing) {
 495     if (!_secondary_free_list.is_empty()) {
 496       if (G1ConcRegionFreeingVerbose) {
 497         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 498                                "forced to look at the secondary_free_list");
 499       }
 500       res = new_region_try_secondary_free_list(is_old);
 501       if (res != NULL) {
 502         return res;
 503       }
 504     }
 505   }
 506 
 507   res = _hrm.allocate_free_region(is_old);
 508 
 509   if (res == NULL) {
 510     if (G1ConcRegionFreeingVerbose) {
 511       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 512                              "res == NULL, trying the secondary_free_list");
 513     }
 514     res = new_region_try_secondary_free_list(is_old);
 515   }
 516   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 517     // Currently, only attempts to allocate GC alloc regions set
 518     // do_expand to true. So, we should only reach here during a
 519     // safepoint. If this assumption changes we might have to
 520     // reconsider the use of _expand_heap_after_alloc_failure.
 521     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 522 
 523     ergo_verbose1(ErgoHeapSizing,
 524                   "attempt heap expansion",
 525                   ergo_format_reason("region allocation request failed")
 526                   ergo_format_byte("allocation request"),
 527                   word_size * HeapWordSize);
 528     if (expand(word_size * HeapWordSize)) {
 529       // Given that expand() succeeded in expanding the heap, and we
 530       // always expand the heap by an amount aligned to the heap
 531       // region size, the free list should in theory not be empty.
 532       // In either case allocate_free_region() will check for NULL.
 533       res = _hrm.allocate_free_region(is_old);
 534     } else {
 535       _expand_heap_after_alloc_failure = false;
 536     }
 537   }
 538   return res;
 539 }
 540 
 541 HeapWord*
 542 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 543                                                            uint num_regions,
 544                                                            size_t word_size,
 545                                                            AllocationContext_t context) {
 546   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 547   assert(is_humongous(word_size), "word_size should be humongous");
 548   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 549 
 550   // Index of last region in the series + 1.
 551   uint last = first + num_regions;
 552 
 553   // We need to initialize the region(s) we just discovered. This is
 554   // a bit tricky given that it can happen concurrently with
 555   // refinement threads refining cards on these regions and
 556   // potentially wanting to refine the BOT as they are scanning
 557   // those cards (this can happen shortly after a cleanup; see CR
 558   // 6991377). So we have to set up the region(s) carefully and in
 559   // a specific order.
 560 
 561   // The word size sum of all the regions we will allocate.
 562   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 563   assert(word_size <= word_size_sum, "sanity");
 564 
 565   // This will be the "starts humongous" region.
 566   HeapRegion* first_hr = region_at(first);
 567   // The header of the new object will be placed at the bottom of
 568   // the first region.
 569   HeapWord* new_obj = first_hr->bottom();
 570   // This will be the new end of the first region in the series that
 571   // should also match the end of the last region in the series.
 572   HeapWord* new_end = new_obj + word_size_sum;
 573   // This will be the new top of the first region that will reflect
 574   // this allocation.
 575   HeapWord* new_top = new_obj + word_size;
 576 
 577   // First, we need to zero the header of the space that we will be
 578   // allocating. When we update top further down, some refinement
 579   // threads might try to scan the region. By zeroing the header we
 580   // ensure that any thread that will try to scan the region will
 581   // come across the zero klass word and bail out.
 582   //
 583   // NOTE: It would not have been correct to have used
 584   // CollectedHeap::fill_with_object() and make the space look like
 585   // an int array. The thread that is doing the allocation will
 586   // later update the object header to a potentially different array
 587   // type and, for a very short period of time, the klass and length
 588   // fields will be inconsistent. This could cause a refinement
 589   // thread to calculate the object size incorrectly.
 590   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 591 
 592   // We will set up the first region as "starts humongous". This
 593   // will also update the BOT covering all the regions to reflect
 594   // that there is a single object that starts at the bottom of the
 595   // first region.
 596   first_hr->set_starts_humongous(new_top, new_end);
 597   first_hr->set_allocation_context(context);
 598   // Then, if there are any, we will set up the "continues
 599   // humongous" regions.
 600   HeapRegion* hr = NULL;
 601   for (uint i = first + 1; i < last; ++i) {
 602     hr = region_at(i);
 603     hr->set_continues_humongous(first_hr);
 604     hr->set_allocation_context(context);
 605   }
 606   // If we have "continues humongous" regions (hr != NULL), then the
 607   // end of the last one should match new_end.
 608   assert(hr == NULL || hr->end() == new_end, "sanity");
 609 
 610   // Up to this point no concurrent thread would have been able to
 611   // do any scanning on any region in this series. All the top
 612   // fields still point to bottom, so the intersection between
 613   // [bottom,top] and [card_start,card_end] will be empty. Before we
 614   // update the top fields, we'll do a storestore to make sure that
 615   // no thread sees the update to top before the zeroing of the
 616   // object header and the BOT initialization.
 617   OrderAccess::storestore();
 618 
 619   // Now that the BOT and the object header have been initialized,
 620   // we can update top of the "starts humongous" region.
 621   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 622          "new_top should be in this region");
 623   first_hr->set_top(new_top);
 624   if (_hr_printer.is_active()) {
 625     HeapWord* bottom = first_hr->bottom();
 626     HeapWord* end = first_hr->orig_end();
 627     if ((first + 1) == last) {
 628       // the series has a single humongous region
 629       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 630     } else {
 631       // the series has more than one humongous regions
 632       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 633     }
 634   }
 635 
 636   // Now, we will update the top fields of the "continues humongous"
 637   // regions. The reason we need to do this is that, otherwise,
 638   // these regions would look empty and this will confuse parts of
 639   // G1. For example, the code that looks for a consecutive number
 640   // of empty regions will consider them empty and try to
 641   // re-allocate them. We can extend is_empty() to also include
 642   // !is_continues_humongous(), but it is easier to just update the top
 643   // fields here. The way we set top for all regions (i.e., top ==
 644   // end for all regions but the last one, top == new_top for the
 645   // last one) is actually used when we will free up the humongous
 646   // region in free_humongous_region().
 647   hr = NULL;
 648   for (uint i = first + 1; i < last; ++i) {
 649     hr = region_at(i);
 650     if ((i + 1) == last) {
 651       // last continues humongous region
 652       assert(hr->bottom() < new_top && new_top <= hr->end(),
 653              "new_top should fall on this region");
 654       hr->set_top(new_top);
 655       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 656     } else {
 657       // not last one
 658       assert(new_top > hr->end(), "new_top should be above this region");
 659       hr->set_top(hr->end());
 660       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 661     }
 662   }
 663   // If we have continues humongous regions (hr != NULL), then the
 664   // end of the last one should match new_end and its top should
 665   // match new_top.
 666   assert(hr == NULL ||
 667          (hr->end() == new_end && hr->top() == new_top), "sanity");
 668   check_bitmaps("Humongous Region Allocation", first_hr);
 669 
 670   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 671   _allocator->increase_used(first_hr->used());
 672   _humongous_set.add(first_hr);
 673 
 674   return new_obj;
 675 }
 676 
 677 // If could fit into free regions w/o expansion, try.
 678 // Otherwise, if can expand, do so.
 679 // Otherwise, if using ex regions might help, try with ex given back.
 680 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 681   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 682 
 683   verify_region_sets_optional();
 684 
 685   uint first = G1_NO_HRM_INDEX;
 686   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 687 
 688   if (obj_regions == 1) {
 689     // Only one region to allocate, try to use a fast path by directly allocating
 690     // from the free lists. Do not try to expand here, we will potentially do that
 691     // later.
 692     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 693     if (hr != NULL) {
 694       first = hr->hrm_index();
 695     }
 696   } else {
 697     // We can't allocate humongous regions spanning more than one region while
 698     // cleanupComplete() is running, since some of the regions we find to be
 699     // empty might not yet be added to the free list. It is not straightforward
 700     // to know in which list they are on so that we can remove them. We only
 701     // need to do this if we need to allocate more than one region to satisfy the
 702     // current humongous allocation request. If we are only allocating one region
 703     // we use the one-region region allocation code (see above), that already
 704     // potentially waits for regions from the secondary free list.
 705     wait_while_free_regions_coming();
 706     append_secondary_free_list_if_not_empty_with_lock();
 707 
 708     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 709     // are lucky enough to find some.
 710     first = _hrm.find_contiguous_only_empty(obj_regions);
 711     if (first != G1_NO_HRM_INDEX) {
 712       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 713     }
 714   }
 715 
 716   if (first == G1_NO_HRM_INDEX) {
 717     // Policy: We could not find enough regions for the humongous object in the
 718     // free list. Look through the heap to find a mix of free and uncommitted regions.
 719     // If so, try expansion.
 720     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 721     if (first != G1_NO_HRM_INDEX) {
 722       // We found something. Make sure these regions are committed, i.e. expand
 723       // the heap. Alternatively we could do a defragmentation GC.
 724       ergo_verbose1(ErgoHeapSizing,
 725                     "attempt heap expansion",
 726                     ergo_format_reason("humongous allocation request failed")
 727                     ergo_format_byte("allocation request"),
 728                     word_size * HeapWordSize);
 729 
 730       _hrm.expand_at(first, obj_regions);
 731       g1_policy()->record_new_heap_size(num_regions());
 732 
 733 #ifdef ASSERT
 734       for (uint i = first; i < first + obj_regions; ++i) {
 735         HeapRegion* hr = region_at(i);
 736         assert(hr->is_free(), "sanity");
 737         assert(hr->is_empty(), "sanity");
 738         assert(is_on_master_free_list(hr), "sanity");
 739       }
 740 #endif
 741       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 742     } else {
 743       // Policy: Potentially trigger a defragmentation GC.
 744     }
 745   }
 746 
 747   HeapWord* result = NULL;
 748   if (first != G1_NO_HRM_INDEX) {
 749     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 750                                                        word_size, context);
 751     assert(result != NULL, "it should always return a valid result");
 752 
 753     // A successful humongous object allocation changes the used space
 754     // information of the old generation so we need to recalculate the
 755     // sizes and update the jstat counters here.
 756     g1mm()->update_sizes();
 757   }
 758 
 759   verify_region_sets_optional();
 760 
 761   return result;
 762 }
 763 
 764 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 765   assert_heap_not_locked_and_not_at_safepoint();
 766   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 767 
 768   unsigned int dummy_gc_count_before;
 769   int dummy_gclocker_retry_count = 0;
 770   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 771 }
 772 
 773 HeapWord*
 774 G1CollectedHeap::mem_allocate(size_t word_size,
 775                               bool*  gc_overhead_limit_was_exceeded) {
 776   assert_heap_not_locked_and_not_at_safepoint();
 777 
 778   // Loop until the allocation is satisfied, or unsatisfied after GC.
 779   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 780     unsigned int gc_count_before;
 781 
 782     HeapWord* result = NULL;
 783     if (!is_humongous(word_size)) {
 784       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 785     } else {
 786       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 787     }
 788     if (result != NULL) {
 789       return result;
 790     }
 791 
 792     // Create the garbage collection operation...
 793     VM_G1CollectForAllocation op(gc_count_before, word_size);
 794     op.set_allocation_context(AllocationContext::current());
 795 
 796     // ...and get the VM thread to execute it.
 797     VMThread::execute(&op);
 798 
 799     if (op.prologue_succeeded() && op.pause_succeeded()) {
 800       // If the operation was successful we'll return the result even
 801       // if it is NULL. If the allocation attempt failed immediately
 802       // after a Full GC, it's unlikely we'll be able to allocate now.
 803       HeapWord* result = op.result();
 804       if (result != NULL && !is_humongous(word_size)) {
 805         // Allocations that take place on VM operations do not do any
 806         // card dirtying and we have to do it here. We only have to do
 807         // this for non-humongous allocations, though.
 808         dirty_young_block(result, word_size);
 809       }
 810       return result;
 811     } else {
 812       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 813         return NULL;
 814       }
 815       assert(op.result() == NULL,
 816              "the result should be NULL if the VM op did not succeed");
 817     }
 818 
 819     // Give a warning if we seem to be looping forever.
 820     if ((QueuedAllocationWarningCount > 0) &&
 821         (try_count % QueuedAllocationWarningCount == 0)) {
 822       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 823     }
 824   }
 825 
 826   ShouldNotReachHere();
 827   return NULL;
 828 }
 829 
 830 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 831                                                    AllocationContext_t context,
 832                                                    unsigned int *gc_count_before_ret,
 833                                                    int* gclocker_retry_count_ret) {
 834   // Make sure you read the note in attempt_allocation_humongous().
 835 
 836   assert_heap_not_locked_and_not_at_safepoint();
 837   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 838          "be called for humongous allocation requests");
 839 
 840   // We should only get here after the first-level allocation attempt
 841   // (attempt_allocation()) failed to allocate.
 842 
 843   // We will loop until a) we manage to successfully perform the
 844   // allocation or b) we successfully schedule a collection which
 845   // fails to perform the allocation. b) is the only case when we'll
 846   // return NULL.
 847   HeapWord* result = NULL;
 848   for (int try_count = 1; /* we'll return */; try_count += 1) {
 849     bool should_try_gc;
 850     unsigned int gc_count_before;
 851 
 852     {
 853       MutexLockerEx x(Heap_lock);
 854       result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
 855                                                                                     false /* bot_updates */);
 856       if (result != NULL) {
 857         return result;
 858       }
 859 
 860       // If we reach here, attempt_allocation_locked() above failed to
 861       // allocate a new region. So the mutator alloc region should be NULL.
 862       assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
 863 
 864       if (GC_locker::is_active_and_needs_gc()) {
 865         if (g1_policy()->can_expand_young_list()) {
 866           // No need for an ergo verbose message here,
 867           // can_expand_young_list() does this when it returns true.
 868           result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
 869                                                                                        false /* bot_updates */);
 870           if (result != NULL) {
 871             return result;
 872           }
 873         }
 874         should_try_gc = false;
 875       } else {
 876         // The GCLocker may not be active but the GCLocker initiated
 877         // GC may not yet have been performed (GCLocker::needs_gc()
 878         // returns true). In this case we do not try this GC and
 879         // wait until the GCLocker initiated GC is performed, and
 880         // then retry the allocation.
 881         if (GC_locker::needs_gc()) {
 882           should_try_gc = false;
 883         } else {
 884           // Read the GC count while still holding the Heap_lock.
 885           gc_count_before = total_collections();
 886           should_try_gc = true;
 887         }
 888       }
 889     }
 890 
 891     if (should_try_gc) {
 892       bool succeeded;
 893       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 894           GCCause::_g1_inc_collection_pause);
 895       if (result != NULL) {
 896         assert(succeeded, "only way to get back a non-NULL result");
 897         return result;
 898       }
 899 
 900       if (succeeded) {
 901         // If we get here we successfully scheduled a collection which
 902         // failed to allocate. No point in trying to allocate
 903         // further. We'll just return NULL.
 904         MutexLockerEx x(Heap_lock);
 905         *gc_count_before_ret = total_collections();
 906         return NULL;
 907       }
 908     } else {
 909       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 910         MutexLockerEx x(Heap_lock);
 911         *gc_count_before_ret = total_collections();
 912         return NULL;
 913       }
 914       // The GCLocker is either active or the GCLocker initiated
 915       // GC has not yet been performed. Stall until it is and
 916       // then retry the allocation.
 917       GC_locker::stall_until_clear();
 918       (*gclocker_retry_count_ret) += 1;
 919     }
 920 
 921     // We can reach here if we were unsuccessful in scheduling a
 922     // collection (because another thread beat us to it) or if we were
 923     // stalled due to the GC locker. In either can we should retry the
 924     // allocation attempt in case another thread successfully
 925     // performed a collection and reclaimed enough space. We do the
 926     // first attempt (without holding the Heap_lock) here and the
 927     // follow-on attempt will be at the start of the next loop
 928     // iteration (after taking the Heap_lock).
 929     result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
 930                                                                            false /* bot_updates */);
 931     if (result != NULL) {
 932       return result;
 933     }
 934 
 935     // Give a warning if we seem to be looping forever.
 936     if ((QueuedAllocationWarningCount > 0) &&
 937         (try_count % QueuedAllocationWarningCount == 0)) {
 938       warning("G1CollectedHeap::attempt_allocation_slow() "
 939               "retries %d times", try_count);
 940     }
 941   }
 942 
 943   ShouldNotReachHere();
 944   return NULL;
 945 }
 946 
 947 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 948                                                         unsigned int * gc_count_before_ret,
 949                                                         int* gclocker_retry_count_ret) {
 950   // The structure of this method has a lot of similarities to
 951   // attempt_allocation_slow(). The reason these two were not merged
 952   // into a single one is that such a method would require several "if
 953   // allocation is not humongous do this, otherwise do that"
 954   // conditional paths which would obscure its flow. In fact, an early
 955   // version of this code did use a unified method which was harder to
 956   // follow and, as a result, it had subtle bugs that were hard to
 957   // track down. So keeping these two methods separate allows each to
 958   // be more readable. It will be good to keep these two in sync as
 959   // much as possible.
 960 
 961   assert_heap_not_locked_and_not_at_safepoint();
 962   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 963          "should only be called for humongous allocations");
 964 
 965   // Humongous objects can exhaust the heap quickly, so we should check if we
 966   // need to start a marking cycle at each humongous object allocation. We do
 967   // the check before we do the actual allocation. The reason for doing it
 968   // before the allocation is that we avoid having to keep track of the newly
 969   // allocated memory while we do a GC.
 970   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 971                                            word_size)) {
 972     collect(GCCause::_g1_humongous_allocation);
 973   }
 974 
 975   // We will loop until a) we manage to successfully perform the
 976   // allocation or b) we successfully schedule a collection which
 977   // fails to perform the allocation. b) is the only case when we'll
 978   // return NULL.
 979   HeapWord* result = NULL;
 980   for (int try_count = 1; /* we'll return */; try_count += 1) {
 981     bool should_try_gc;
 982     unsigned int gc_count_before;
 983 
 984     {
 985       MutexLockerEx x(Heap_lock);
 986 
 987       // Given that humongous objects are not allocated in young
 988       // regions, we'll first try to do the allocation without doing a
 989       // collection hoping that there's enough space in the heap.
 990       result = humongous_obj_allocate(word_size, AllocationContext::current());
 991       if (result != NULL) {
 992         return result;
 993       }
 994 
 995       if (GC_locker::is_active_and_needs_gc()) {
 996         should_try_gc = false;
 997       } else {
 998          // The GCLocker may not be active but the GCLocker initiated
 999         // GC may not yet have been performed (GCLocker::needs_gc()
1000         // returns true). In this case we do not try this GC and
1001         // wait until the GCLocker initiated GC is performed, and
1002         // then retry the allocation.
1003         if (GC_locker::needs_gc()) {
1004           should_try_gc = false;
1005         } else {
1006           // Read the GC count while still holding the Heap_lock.
1007           gc_count_before = total_collections();
1008           should_try_gc = true;
1009         }
1010       }
1011     }
1012 
1013     if (should_try_gc) {
1014       // If we failed to allocate the humongous object, we should try to
1015       // do a collection pause (if we're allowed) in case it reclaims
1016       // enough space for the allocation to succeed after the pause.
1017 
1018       bool succeeded;
1019       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1020           GCCause::_g1_humongous_allocation);
1021       if (result != NULL) {
1022         assert(succeeded, "only way to get back a non-NULL result");
1023         return result;
1024       }
1025 
1026       if (succeeded) {
1027         // If we get here we successfully scheduled a collection which
1028         // failed to allocate. No point in trying to allocate
1029         // further. We'll just return NULL.
1030         MutexLockerEx x(Heap_lock);
1031         *gc_count_before_ret = total_collections();
1032         return NULL;
1033       }
1034     } else {
1035       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1036         MutexLockerEx x(Heap_lock);
1037         *gc_count_before_ret = total_collections();
1038         return NULL;
1039       }
1040       // The GCLocker is either active or the GCLocker initiated
1041       // GC has not yet been performed. Stall until it is and
1042       // then retry the allocation.
1043       GC_locker::stall_until_clear();
1044       (*gclocker_retry_count_ret) += 1;
1045     }
1046 
1047     // We can reach here if we were unsuccessful in scheduling a
1048     // collection (because another thread beat us to it) or if we were
1049     // stalled due to the GC locker. In either can we should retry the
1050     // allocation attempt in case another thread successfully
1051     // performed a collection and reclaimed enough space.  Give a
1052     // warning if we seem to be looping forever.
1053 
1054     if ((QueuedAllocationWarningCount > 0) &&
1055         (try_count % QueuedAllocationWarningCount == 0)) {
1056       warning("G1CollectedHeap::attempt_allocation_humongous() "
1057               "retries %d times", try_count);
1058     }
1059   }
1060 
1061   ShouldNotReachHere();
1062   return NULL;
1063 }
1064 
1065 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1066                                                            AllocationContext_t context,
1067                                                            bool expect_null_mutator_alloc_region) {
1068   assert_at_safepoint(true /* should_be_vm_thread */);
1069   assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1070                                              !expect_null_mutator_alloc_region,
1071          "the current alloc region was unexpectedly found to be non-NULL");
1072 
1073   if (!is_humongous(word_size)) {
1074     return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1075                                                       false /* bot_updates */);
1076   } else {
1077     HeapWord* result = humongous_obj_allocate(word_size, context);
1078     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1079       g1_policy()->set_initiate_conc_mark_if_possible();
1080     }
1081     return result;
1082   }
1083 
1084   ShouldNotReachHere();
1085 }
1086 
1087 class PostMCRemSetClearClosure: public HeapRegionClosure {
1088   G1CollectedHeap* _g1h;
1089   ModRefBarrierSet* _mr_bs;
1090 public:
1091   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1092     _g1h(g1h), _mr_bs(mr_bs) {}
1093 
1094   bool doHeapRegion(HeapRegion* r) {
1095     HeapRegionRemSet* hrrs = r->rem_set();
1096 
1097     if (r->is_continues_humongous()) {
1098       // We'll assert that the strong code root list and RSet is empty
1099       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1100       assert(hrrs->occupied() == 0, "RSet should be empty");
1101       return false;
1102     }
1103 
1104     _g1h->reset_gc_time_stamps(r);
1105     hrrs->clear();
1106     // You might think here that we could clear just the cards
1107     // corresponding to the used region.  But no: if we leave a dirty card
1108     // in a region we might allocate into, then it would prevent that card
1109     // from being enqueued, and cause it to be missed.
1110     // Re: the performance cost: we shouldn't be doing full GC anyway!
1111     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1112 
1113     return false;
1114   }
1115 };
1116 
1117 void G1CollectedHeap::clear_rsets_post_compaction() {
1118   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1119   heap_region_iterate(&rs_clear);
1120 }
1121 
1122 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1123   G1CollectedHeap*   _g1h;
1124   UpdateRSOopClosure _cl;
1125   int                _worker_i;
1126 public:
1127   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1128     _cl(g1->g1_rem_set(), worker_i),
1129     _worker_i(worker_i),
1130     _g1h(g1)
1131   { }
1132 
1133   bool doHeapRegion(HeapRegion* r) {
1134     if (!r->is_continues_humongous()) {
1135       _cl.set_from(r);
1136       r->oop_iterate(&_cl);
1137     }
1138     return false;
1139   }
1140 };
1141 
1142 class ParRebuildRSTask: public AbstractGangTask {
1143   G1CollectedHeap* _g1;
1144   HeapRegionClaimer _hrclaimer;
1145 
1146 public:
1147   ParRebuildRSTask(G1CollectedHeap* g1) :
1148       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1149 
1150   void work(uint worker_id) {
1151     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1152     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1153   }
1154 };
1155 
1156 class PostCompactionPrinterClosure: public HeapRegionClosure {
1157 private:
1158   G1HRPrinter* _hr_printer;
1159 public:
1160   bool doHeapRegion(HeapRegion* hr) {
1161     assert(!hr->is_young(), "not expecting to find young regions");
1162     if (hr->is_free()) {
1163       // We only generate output for non-empty regions.
1164     } else if (hr->is_starts_humongous()) {
1165       if (hr->region_num() == 1) {
1166         // single humongous region
1167         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1168       } else {
1169         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1170       }
1171     } else if (hr->is_continues_humongous()) {
1172       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1173     } else if (hr->is_old()) {
1174       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1175     } else {
1176       ShouldNotReachHere();
1177     }
1178     return false;
1179   }
1180 
1181   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1182     : _hr_printer(hr_printer) { }
1183 };
1184 
1185 void G1CollectedHeap::print_hrm_post_compaction() {
1186   PostCompactionPrinterClosure cl(hr_printer());
1187   heap_region_iterate(&cl);
1188 }
1189 
1190 bool G1CollectedHeap::do_collection(bool explicit_gc,
1191                                     bool clear_all_soft_refs,
1192                                     size_t word_size) {
1193   assert_at_safepoint(true /* should_be_vm_thread */);
1194 
1195   if (GC_locker::check_active_before_gc()) {
1196     return false;
1197   }
1198 
1199   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1200   gc_timer->register_gc_start();
1201 
1202   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1203   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1204 
1205   SvcGCMarker sgcm(SvcGCMarker::FULL);
1206   ResourceMark rm;
1207 
1208   print_heap_before_gc();
1209   trace_heap_before_gc(gc_tracer);
1210 
1211   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1212 
1213   verify_region_sets_optional();
1214 
1215   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1216                            collector_policy()->should_clear_all_soft_refs();
1217 
1218   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1219 
1220   {
1221     IsGCActiveMark x;
1222 
1223     // Timing
1224     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1225     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1226     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1227 
1228     {
1229       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1230       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1231       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1232 
1233       double start = os::elapsedTime();
1234       g1_policy()->record_full_collection_start();
1235 
1236       // Note: When we have a more flexible GC logging framework that
1237       // allows us to add optional attributes to a GC log record we
1238       // could consider timing and reporting how long we wait in the
1239       // following two methods.
1240       wait_while_free_regions_coming();
1241       // If we start the compaction before the CM threads finish
1242       // scanning the root regions we might trip them over as we'll
1243       // be moving objects / updating references. So let's wait until
1244       // they are done. By telling them to abort, they should complete
1245       // early.
1246       _cm->root_regions()->abort();
1247       _cm->root_regions()->wait_until_scan_finished();
1248       append_secondary_free_list_if_not_empty_with_lock();
1249 
1250       gc_prologue(true);
1251       increment_total_collections(true /* full gc */);
1252       increment_old_marking_cycles_started();
1253 
1254       assert(used() == recalculate_used(), "Should be equal");
1255 
1256       verify_before_gc();
1257 
1258       check_bitmaps("Full GC Start");
1259       pre_full_gc_dump(gc_timer);
1260 
1261       COMPILER2_PRESENT(DerivedPointerTable::clear());
1262 
1263       // Disable discovery and empty the discovered lists
1264       // for the CM ref processor.
1265       ref_processor_cm()->disable_discovery();
1266       ref_processor_cm()->abandon_partial_discovery();
1267       ref_processor_cm()->verify_no_references_recorded();
1268 
1269       // Abandon current iterations of concurrent marking and concurrent
1270       // refinement, if any are in progress. We have to do this before
1271       // wait_until_scan_finished() below.
1272       concurrent_mark()->abort();
1273 
1274       // Make sure we'll choose a new allocation region afterwards.
1275       _allocator->release_mutator_alloc_region();
1276       _allocator->abandon_gc_alloc_regions();
1277       g1_rem_set()->cleanupHRRS();
1278 
1279       // We should call this after we retire any currently active alloc
1280       // regions so that all the ALLOC / RETIRE events are generated
1281       // before the start GC event.
1282       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1283 
1284       // We may have added regions to the current incremental collection
1285       // set between the last GC or pause and now. We need to clear the
1286       // incremental collection set and then start rebuilding it afresh
1287       // after this full GC.
1288       abandon_collection_set(g1_policy()->inc_cset_head());
1289       g1_policy()->clear_incremental_cset();
1290       g1_policy()->stop_incremental_cset_building();
1291 
1292       tear_down_region_sets(false /* free_list_only */);
1293       g1_policy()->set_gcs_are_young(true);
1294 
1295       // See the comments in g1CollectedHeap.hpp and
1296       // G1CollectedHeap::ref_processing_init() about
1297       // how reference processing currently works in G1.
1298 
1299       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1300       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1301 
1302       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1303       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1304 
1305       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1306       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1307 
1308       // Do collection work
1309       {
1310         HandleMark hm;  // Discard invalid handles created during gc
1311         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1312       }
1313 
1314       assert(num_free_regions() == 0, "we should not have added any free regions");
1315       rebuild_region_sets(false /* free_list_only */);
1316 
1317       // Enqueue any discovered reference objects that have
1318       // not been removed from the discovered lists.
1319       ref_processor_stw()->enqueue_discovered_references();
1320 
1321       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1322 
1323       MemoryService::track_memory_usage();
1324 
1325       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1326       ref_processor_stw()->verify_no_references_recorded();
1327 
1328       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1329       ClassLoaderDataGraph::purge();
1330       MetaspaceAux::verify_metrics();
1331 
1332       // Note: since we've just done a full GC, concurrent
1333       // marking is no longer active. Therefore we need not
1334       // re-enable reference discovery for the CM ref processor.
1335       // That will be done at the start of the next marking cycle.
1336       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1337       ref_processor_cm()->verify_no_references_recorded();
1338 
1339       reset_gc_time_stamp();
1340       // Since everything potentially moved, we will clear all remembered
1341       // sets, and clear all cards.  Later we will rebuild remembered
1342       // sets. We will also reset the GC time stamps of the regions.
1343       clear_rsets_post_compaction();
1344       check_gc_time_stamps();
1345 
1346       // Resize the heap if necessary.
1347       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1348 
1349       if (_hr_printer.is_active()) {
1350         // We should do this after we potentially resize the heap so
1351         // that all the COMMIT / UNCOMMIT events are generated before
1352         // the end GC event.
1353 
1354         print_hrm_post_compaction();
1355         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1356       }
1357 
1358       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1359       if (hot_card_cache->use_cache()) {
1360         hot_card_cache->reset_card_counts();
1361         hot_card_cache->reset_hot_cache();
1362       }
1363 
1364       // Rebuild remembered sets of all regions.
1365       uint n_workers =
1366         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1367                                                 workers()->active_workers(),
1368                                                 Threads::number_of_non_daemon_threads());
1369       assert(UseDynamicNumberOfGCThreads ||
1370              n_workers == workers()->total_workers(),
1371              "If not dynamic should be using all the  workers");
1372       workers()->set_active_workers(n_workers);
1373       // Set parallel threads in the heap (_n_par_threads) only
1374       // before a parallel phase and always reset it to 0 after
1375       // the phase so that the number of parallel threads does
1376       // no get carried forward to a serial phase where there
1377       // may be code that is "possibly_parallel".
1378       set_par_threads(n_workers);
1379 
1380       ParRebuildRSTask rebuild_rs_task(this);
1381       assert(UseDynamicNumberOfGCThreads ||
1382              workers()->active_workers() == workers()->total_workers(),
1383              "Unless dynamic should use total workers");
1384       // Use the most recent number of  active workers
1385       assert(workers()->active_workers() > 0,
1386              "Active workers not properly set");
1387       set_par_threads(workers()->active_workers());
1388       workers()->run_task(&rebuild_rs_task);
1389       set_par_threads(0);
1390 
1391       // Rebuild the strong code root lists for each region
1392       rebuild_strong_code_roots();
1393 
1394       if (true) { // FIXME
1395         MetaspaceGC::compute_new_size();
1396       }
1397 
1398 #ifdef TRACESPINNING
1399       ParallelTaskTerminator::print_termination_counts();
1400 #endif
1401 
1402       // Discard all rset updates
1403       JavaThread::dirty_card_queue_set().abandon_logs();
1404       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1405 
1406       _young_list->reset_sampled_info();
1407       // At this point there should be no regions in the
1408       // entire heap tagged as young.
1409       assert(check_young_list_empty(true /* check_heap */),
1410              "young list should be empty at this point");
1411 
1412       // Update the number of full collections that have been completed.
1413       increment_old_marking_cycles_completed(false /* concurrent */);
1414 
1415       _hrm.verify_optional();
1416       verify_region_sets_optional();
1417 
1418       verify_after_gc();
1419 
1420       // Clear the previous marking bitmap, if needed for bitmap verification.
1421       // Note we cannot do this when we clear the next marking bitmap in
1422       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1423       // objects marked during a full GC against the previous bitmap.
1424       // But we need to clear it before calling check_bitmaps below since
1425       // the full GC has compacted objects and updated TAMS but not updated
1426       // the prev bitmap.
1427       if (G1VerifyBitmaps) {
1428         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1429       }
1430       check_bitmaps("Full GC End");
1431 
1432       // Start a new incremental collection set for the next pause
1433       assert(g1_policy()->collection_set() == NULL, "must be");
1434       g1_policy()->start_incremental_cset_building();
1435 
1436       clear_cset_fast_test();
1437 
1438       _allocator->init_mutator_alloc_region();
1439 
1440       double end = os::elapsedTime();
1441       g1_policy()->record_full_collection_end();
1442 
1443       if (G1Log::fine()) {
1444         g1_policy()->print_heap_transition();
1445       }
1446 
1447       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1448       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1449       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1450       // before any GC notifications are raised.
1451       g1mm()->update_sizes();
1452 
1453       gc_epilogue(true);
1454     }
1455 
1456     if (G1Log::finer()) {
1457       g1_policy()->print_detailed_heap_transition(true /* full */);
1458     }
1459 
1460     print_heap_after_gc();
1461     trace_heap_after_gc(gc_tracer);
1462 
1463     post_full_gc_dump(gc_timer);
1464 
1465     gc_timer->register_gc_end();
1466     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1467   }
1468 
1469   return true;
1470 }
1471 
1472 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1473   // do_collection() will return whether it succeeded in performing
1474   // the GC. Currently, there is no facility on the
1475   // do_full_collection() API to notify the caller than the collection
1476   // did not succeed (e.g., because it was locked out by the GC
1477   // locker). So, right now, we'll ignore the return value.
1478   bool dummy = do_collection(true,                /* explicit_gc */
1479                              clear_all_soft_refs,
1480                              0                    /* word_size */);
1481 }
1482 
1483 // This code is mostly copied from TenuredGeneration.
1484 void
1485 G1CollectedHeap::
1486 resize_if_necessary_after_full_collection(size_t word_size) {
1487   // Include the current allocation, if any, and bytes that will be
1488   // pre-allocated to support collections, as "used".
1489   const size_t used_after_gc = used();
1490   const size_t capacity_after_gc = capacity();
1491   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1492 
1493   // This is enforced in arguments.cpp.
1494   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1495          "otherwise the code below doesn't make sense");
1496 
1497   // We don't have floating point command-line arguments
1498   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1499   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1500   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1501   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1502 
1503   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1504   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1505 
1506   // We have to be careful here as these two calculations can overflow
1507   // 32-bit size_t's.
1508   double used_after_gc_d = (double) used_after_gc;
1509   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1510   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1511 
1512   // Let's make sure that they are both under the max heap size, which
1513   // by default will make them fit into a size_t.
1514   double desired_capacity_upper_bound = (double) max_heap_size;
1515   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1516                                     desired_capacity_upper_bound);
1517   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1518                                     desired_capacity_upper_bound);
1519 
1520   // We can now safely turn them into size_t's.
1521   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1522   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1523 
1524   // This assert only makes sense here, before we adjust them
1525   // with respect to the min and max heap size.
1526   assert(minimum_desired_capacity <= maximum_desired_capacity,
1527          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1528                  "maximum_desired_capacity = "SIZE_FORMAT,
1529                  minimum_desired_capacity, maximum_desired_capacity));
1530 
1531   // Should not be greater than the heap max size. No need to adjust
1532   // it with respect to the heap min size as it's a lower bound (i.e.,
1533   // we'll try to make the capacity larger than it, not smaller).
1534   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1535   // Should not be less than the heap min size. No need to adjust it
1536   // with respect to the heap max size as it's an upper bound (i.e.,
1537   // we'll try to make the capacity smaller than it, not greater).
1538   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1539 
1540   if (capacity_after_gc < minimum_desired_capacity) {
1541     // Don't expand unless it's significant
1542     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1543     ergo_verbose4(ErgoHeapSizing,
1544                   "attempt heap expansion",
1545                   ergo_format_reason("capacity lower than "
1546                                      "min desired capacity after Full GC")
1547                   ergo_format_byte("capacity")
1548                   ergo_format_byte("occupancy")
1549                   ergo_format_byte_perc("min desired capacity"),
1550                   capacity_after_gc, used_after_gc,
1551                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1552     expand(expand_bytes);
1553 
1554     // No expansion, now see if we want to shrink
1555   } else if (capacity_after_gc > maximum_desired_capacity) {
1556     // Capacity too large, compute shrinking size
1557     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1558     ergo_verbose4(ErgoHeapSizing,
1559                   "attempt heap shrinking",
1560                   ergo_format_reason("capacity higher than "
1561                                      "max desired capacity after Full GC")
1562                   ergo_format_byte("capacity")
1563                   ergo_format_byte("occupancy")
1564                   ergo_format_byte_perc("max desired capacity"),
1565                   capacity_after_gc, used_after_gc,
1566                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1567     shrink(shrink_bytes);
1568   }
1569 }
1570 
1571 
1572 HeapWord*
1573 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1574                                            AllocationContext_t context,
1575                                            bool* succeeded) {
1576   assert_at_safepoint(true /* should_be_vm_thread */);
1577 
1578   *succeeded = true;
1579   // Let's attempt the allocation first.
1580   HeapWord* result =
1581     attempt_allocation_at_safepoint(word_size,
1582                                     context,
1583                                     false /* expect_null_mutator_alloc_region */);
1584   if (result != NULL) {
1585     assert(*succeeded, "sanity");
1586     return result;
1587   }
1588 
1589   // In a G1 heap, we're supposed to keep allocation from failing by
1590   // incremental pauses.  Therefore, at least for now, we'll favor
1591   // expansion over collection.  (This might change in the future if we can
1592   // do something smarter than full collection to satisfy a failed alloc.)
1593   result = expand_and_allocate(word_size, context);
1594   if (result != NULL) {
1595     assert(*succeeded, "sanity");
1596     return result;
1597   }
1598 
1599   // Expansion didn't work, we'll try to do a Full GC.
1600   bool gc_succeeded = do_collection(false, /* explicit_gc */
1601                                     false, /* clear_all_soft_refs */
1602                                     word_size);
1603   if (!gc_succeeded) {
1604     *succeeded = false;
1605     return NULL;
1606   }
1607 
1608   // Retry the allocation
1609   result = attempt_allocation_at_safepoint(word_size,
1610                                            context,
1611                                            true /* expect_null_mutator_alloc_region */);
1612   if (result != NULL) {
1613     assert(*succeeded, "sanity");
1614     return result;
1615   }
1616 
1617   // Then, try a Full GC that will collect all soft references.
1618   gc_succeeded = do_collection(false, /* explicit_gc */
1619                                true,  /* clear_all_soft_refs */
1620                                word_size);
1621   if (!gc_succeeded) {
1622     *succeeded = false;
1623     return NULL;
1624   }
1625 
1626   // Retry the allocation once more
1627   result = attempt_allocation_at_safepoint(word_size,
1628                                            context,
1629                                            true /* expect_null_mutator_alloc_region */);
1630   if (result != NULL) {
1631     assert(*succeeded, "sanity");
1632     return result;
1633   }
1634 
1635   assert(!collector_policy()->should_clear_all_soft_refs(),
1636          "Flag should have been handled and cleared prior to this point");
1637 
1638   // What else?  We might try synchronous finalization later.  If the total
1639   // space available is large enough for the allocation, then a more
1640   // complete compaction phase than we've tried so far might be
1641   // appropriate.
1642   assert(*succeeded, "sanity");
1643   return NULL;
1644 }
1645 
1646 // Attempting to expand the heap sufficiently
1647 // to support an allocation of the given "word_size".  If
1648 // successful, perform the allocation and return the address of the
1649 // allocated block, or else "NULL".
1650 
1651 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1652   assert_at_safepoint(true /* should_be_vm_thread */);
1653 
1654   verify_region_sets_optional();
1655 
1656   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1657   ergo_verbose1(ErgoHeapSizing,
1658                 "attempt heap expansion",
1659                 ergo_format_reason("allocation request failed")
1660                 ergo_format_byte("allocation request"),
1661                 word_size * HeapWordSize);
1662   if (expand(expand_bytes)) {
1663     _hrm.verify_optional();
1664     verify_region_sets_optional();
1665     return attempt_allocation_at_safepoint(word_size,
1666                                            context,
1667                                            false /* expect_null_mutator_alloc_region */);
1668   }
1669   return NULL;
1670 }
1671 
1672 bool G1CollectedHeap::expand(size_t expand_bytes) {
1673   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1674   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1675                                        HeapRegion::GrainBytes);
1676   ergo_verbose2(ErgoHeapSizing,
1677                 "expand the heap",
1678                 ergo_format_byte("requested expansion amount")
1679                 ergo_format_byte("attempted expansion amount"),
1680                 expand_bytes, aligned_expand_bytes);
1681 
1682   if (is_maximal_no_gc()) {
1683     ergo_verbose0(ErgoHeapSizing,
1684                       "did not expand the heap",
1685                       ergo_format_reason("heap already fully expanded"));
1686     return false;
1687   }
1688 
1689   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1690   assert(regions_to_expand > 0, "Must expand by at least one region");
1691 
1692   uint expanded_by = _hrm.expand_by(regions_to_expand);
1693 
1694   if (expanded_by > 0) {
1695     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1696     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1697     g1_policy()->record_new_heap_size(num_regions());
1698   } else {
1699     ergo_verbose0(ErgoHeapSizing,
1700                   "did not expand the heap",
1701                   ergo_format_reason("heap expansion operation failed"));
1702     // The expansion of the virtual storage space was unsuccessful.
1703     // Let's see if it was because we ran out of swap.
1704     if (G1ExitOnExpansionFailure &&
1705         _hrm.available() >= regions_to_expand) {
1706       // We had head room...
1707       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1708     }
1709   }
1710   return regions_to_expand > 0;
1711 }
1712 
1713 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1714   size_t aligned_shrink_bytes =
1715     ReservedSpace::page_align_size_down(shrink_bytes);
1716   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1717                                          HeapRegion::GrainBytes);
1718   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1719 
1720   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1721   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1722 
1723   ergo_verbose3(ErgoHeapSizing,
1724                 "shrink the heap",
1725                 ergo_format_byte("requested shrinking amount")
1726                 ergo_format_byte("aligned shrinking amount")
1727                 ergo_format_byte("attempted shrinking amount"),
1728                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1729   if (num_regions_removed > 0) {
1730     g1_policy()->record_new_heap_size(num_regions());
1731   } else {
1732     ergo_verbose0(ErgoHeapSizing,
1733                   "did not shrink the heap",
1734                   ergo_format_reason("heap shrinking operation failed"));
1735   }
1736 }
1737 
1738 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1739   verify_region_sets_optional();
1740 
1741   // We should only reach here at the end of a Full GC which means we
1742   // should not not be holding to any GC alloc regions. The method
1743   // below will make sure of that and do any remaining clean up.
1744   _allocator->abandon_gc_alloc_regions();
1745 
1746   // Instead of tearing down / rebuilding the free lists here, we
1747   // could instead use the remove_all_pending() method on free_list to
1748   // remove only the ones that we need to remove.
1749   tear_down_region_sets(true /* free_list_only */);
1750   shrink_helper(shrink_bytes);
1751   rebuild_region_sets(true /* free_list_only */);
1752 
1753   _hrm.verify_optional();
1754   verify_region_sets_optional();
1755 }
1756 
1757 // Public methods.
1758 
1759 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1760 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1761 #endif // _MSC_VER
1762 
1763 
1764 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1765   SharedHeap(policy_),
1766   _g1_policy(policy_),
1767   _dirty_card_queue_set(false),
1768   _into_cset_dirty_card_queue_set(false),
1769   _is_alive_closure_cm(this),
1770   _is_alive_closure_stw(this),
1771   _ref_processor_cm(NULL),
1772   _ref_processor_stw(NULL),
1773   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1774   _bot_shared(NULL),
1775   _evac_failure_scan_stack(NULL),
1776   _mark_in_progress(false),
1777   _cg1r(NULL),
1778   _g1mm(NULL),
1779   _refine_cte_cl(NULL),
1780   _full_collection(false),
1781   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1782   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1783   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1784   _humongous_is_live(),
1785   _has_humongous_reclaim_candidates(false),
1786   _free_regions_coming(false),
1787   _young_list(new YoungList(this)),
1788   _gc_time_stamp(0),
1789   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1790   _old_plab_stats(OldPLABSize, PLABWeight),
1791   _expand_heap_after_alloc_failure(true),
1792   _surviving_young_words(NULL),
1793   _old_marking_cycles_started(0),
1794   _old_marking_cycles_completed(0),
1795   _concurrent_cycle_started(false),
1796   _heap_summary_sent(false),
1797   _in_cset_fast_test(),
1798   _dirty_cards_region_list(NULL),
1799   _worker_cset_start_region(NULL),
1800   _worker_cset_start_region_time_stamp(NULL),
1801   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1802   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1803   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1804   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1805 
1806   _g1h = this;
1807   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1808     vm_exit_during_initialization("Failed necessary allocation.");
1809   }
1810 
1811   _allocator = G1Allocator::create_allocator(_g1h);
1812   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1813 
1814   int n_queues = MAX2((int)ParallelGCThreads, 1);
1815   _task_queues = new RefToScanQueueSet(n_queues);
1816 
1817   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1818   assert(n_rem_sets > 0, "Invariant.");
1819 
1820   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1821   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1822   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1823 
1824   for (int i = 0; i < n_queues; i++) {
1825     RefToScanQueue* q = new RefToScanQueue();
1826     q->initialize();
1827     _task_queues->register_queue(i, q);
1828     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1829   }
1830   clear_cset_start_regions();
1831 
1832   // Initialize the G1EvacuationFailureALot counters and flags.
1833   NOT_PRODUCT(reset_evacuation_should_fail();)
1834 
1835   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1836 }
1837 
1838 jint G1CollectedHeap::initialize() {
1839   CollectedHeap::pre_initialize();
1840   os::enable_vtime();
1841 
1842   G1Log::init();
1843 
1844   // Necessary to satisfy locking discipline assertions.
1845 
1846   MutexLocker x(Heap_lock);
1847 
1848   // We have to initialize the printer before committing the heap, as
1849   // it will be used then.
1850   _hr_printer.set_active(G1PrintHeapRegions);
1851 
1852   // While there are no constraints in the GC code that HeapWordSize
1853   // be any particular value, there are multiple other areas in the
1854   // system which believe this to be true (e.g. oop->object_size in some
1855   // cases incorrectly returns the size in wordSize units rather than
1856   // HeapWordSize).
1857   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1858 
1859   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1860   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1861   size_t heap_alignment = collector_policy()->heap_alignment();
1862 
1863   // Ensure that the sizes are properly aligned.
1864   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1865   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1866   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1867 
1868   _refine_cte_cl = new RefineCardTableEntryClosure();
1869 
1870   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1871 
1872   // Reserve the maximum.
1873 
1874   // When compressed oops are enabled, the preferred heap base
1875   // is calculated by subtracting the requested size from the
1876   // 32Gb boundary and using the result as the base address for
1877   // heap reservation. If the requested size is not aligned to
1878   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1879   // into the ReservedHeapSpace constructor) then the actual
1880   // base of the reserved heap may end up differing from the
1881   // address that was requested (i.e. the preferred heap base).
1882   // If this happens then we could end up using a non-optimal
1883   // compressed oops mode.
1884 
1885   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1886                                                  heap_alignment);
1887 
1888   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1889 
1890   // Create the gen rem set (and barrier set) for the entire reserved region.
1891   _rem_set = collector_policy()->create_rem_set(reserved_region(), 2);
1892   set_barrier_set(rem_set()->bs());
1893   if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1894     vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1895     return JNI_ENOMEM;
1896   }
1897 
1898   // Also create a G1 rem set.
1899   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1900 
1901   // Carve out the G1 part of the heap.
1902 
1903   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1904   G1RegionToSpaceMapper* heap_storage =
1905     G1RegionToSpaceMapper::create_mapper(g1_rs,
1906                                          UseLargePages ? os::large_page_size() : os::vm_page_size(),
1907                                          HeapRegion::GrainBytes,
1908                                          1,
1909                                          mtJavaHeap);
1910   heap_storage->set_mapping_changed_listener(&_listener);
1911 
1912   // Reserve space for the block offset table. We do not support automatic uncommit
1913   // for the card table at this time. BOT only.
1914   ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1915   G1RegionToSpaceMapper* bot_storage =
1916     G1RegionToSpaceMapper::create_mapper(bot_rs,
1917                                          os::vm_page_size(),
1918                                          HeapRegion::GrainBytes,
1919                                          G1BlockOffsetSharedArray::N_bytes,
1920                                          mtGC);
1921 
1922   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1923   G1RegionToSpaceMapper* cardtable_storage =
1924     G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1925                                          os::vm_page_size(),
1926                                          HeapRegion::GrainBytes,
1927                                          G1BlockOffsetSharedArray::N_bytes,
1928                                          mtGC);
1929 
1930   // Reserve space for the card counts table.
1931   ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1932   G1RegionToSpaceMapper* card_counts_storage =
1933     G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1934                                          os::vm_page_size(),
1935                                          HeapRegion::GrainBytes,
1936                                          G1BlockOffsetSharedArray::N_bytes,
1937                                          mtGC);
1938 
1939   // Reserve space for prev and next bitmap.
1940   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1941 
1942   ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1943   G1RegionToSpaceMapper* prev_bitmap_storage =
1944     G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1945                                          os::vm_page_size(),
1946                                          HeapRegion::GrainBytes,
1947                                          CMBitMap::mark_distance(),
1948                                          mtGC);
1949 
1950   ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1951   G1RegionToSpaceMapper* next_bitmap_storage =
1952     G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1953                                          os::vm_page_size(),
1954                                          HeapRegion::GrainBytes,
1955                                          CMBitMap::mark_distance(),
1956                                          mtGC);
1957 
1958   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1959   g1_barrier_set()->initialize(cardtable_storage);
1960    // Do later initialization work for concurrent refinement.
1961   _cg1r->init(card_counts_storage);
1962 
1963   // 6843694 - ensure that the maximum region index can fit
1964   // in the remembered set structures.
1965   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1966   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1967 
1968   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1969   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1970   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1971             "too many cards per region");
1972 
1973   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1974 
1975   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1976 
1977   _g1h = this;
1978 
1979   _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1980   _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1981 
1982   // Create the ConcurrentMark data structure and thread.
1983   // (Must do this late, so that "max_regions" is defined.)
1984   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1985   if (_cm == NULL || !_cm->completed_initialization()) {
1986     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1987     return JNI_ENOMEM;
1988   }
1989   _cmThread = _cm->cmThread();
1990 
1991   // Initialize the from_card cache structure of HeapRegionRemSet.
1992   HeapRegionRemSet::init_heap(max_regions());
1993 
1994   // Now expand into the initial heap size.
1995   if (!expand(init_byte_size)) {
1996     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1997     return JNI_ENOMEM;
1998   }
1999 
2000   // Perform any initialization actions delegated to the policy.
2001   g1_policy()->init();
2002 
2003   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2004                                                SATB_Q_FL_lock,
2005                                                G1SATBProcessCompletedThreshold,
2006                                                Shared_SATB_Q_lock);
2007 
2008   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2009                                                 DirtyCardQ_CBL_mon,
2010                                                 DirtyCardQ_FL_lock,
2011                                                 concurrent_g1_refine()->yellow_zone(),
2012                                                 concurrent_g1_refine()->red_zone(),
2013                                                 Shared_DirtyCardQ_lock);
2014 
2015   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2016                                     DirtyCardQ_CBL_mon,
2017                                     DirtyCardQ_FL_lock,
2018                                     -1, // never trigger processing
2019                                     -1, // no limit on length
2020                                     Shared_DirtyCardQ_lock,
2021                                     &JavaThread::dirty_card_queue_set());
2022 
2023   // Initialize the card queue set used to hold cards containing
2024   // references into the collection set.
2025   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2026                                              DirtyCardQ_CBL_mon,
2027                                              DirtyCardQ_FL_lock,
2028                                              -1, // never trigger processing
2029                                              -1, // no limit on length
2030                                              Shared_DirtyCardQ_lock,
2031                                              &JavaThread::dirty_card_queue_set());
2032 
2033   // In case we're keeping closure specialization stats, initialize those
2034   // counts and that mechanism.
2035   SpecializationStats::clear();
2036 
2037   // Here we allocate the dummy HeapRegion that is required by the
2038   // G1AllocRegion class.
2039   HeapRegion* dummy_region = _hrm.get_dummy_region();
2040 
2041   // We'll re-use the same region whether the alloc region will
2042   // require BOT updates or not and, if it doesn't, then a non-young
2043   // region will complain that it cannot support allocations without
2044   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2045   dummy_region->set_eden();
2046   // Make sure it's full.
2047   dummy_region->set_top(dummy_region->end());
2048   G1AllocRegion::setup(this, dummy_region);
2049 
2050   _allocator->init_mutator_alloc_region();
2051 
2052   // Do create of the monitoring and management support so that
2053   // values in the heap have been properly initialized.
2054   _g1mm = new G1MonitoringSupport(this);
2055 
2056   G1StringDedup::initialize();
2057 
2058   return JNI_OK;
2059 }
2060 
2061 void G1CollectedHeap::stop() {
2062   // Stop all concurrent threads. We do this to make sure these threads
2063   // do not continue to execute and access resources (e.g. gclog_or_tty)
2064   // that are destroyed during shutdown.
2065   _cg1r->stop();
2066   _cmThread->stop();
2067   if (G1StringDedup::is_enabled()) {
2068     G1StringDedup::stop();
2069   }
2070 }
2071 
2072 void G1CollectedHeap::clear_humongous_is_live_table() {
2073   guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2074   _humongous_is_live.clear();
2075 }
2076 
2077 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2078   return HeapRegion::max_region_size();
2079 }
2080 
2081 void G1CollectedHeap::ref_processing_init() {
2082   // Reference processing in G1 currently works as follows:
2083   //
2084   // * There are two reference processor instances. One is
2085   //   used to record and process discovered references
2086   //   during concurrent marking; the other is used to
2087   //   record and process references during STW pauses
2088   //   (both full and incremental).
2089   // * Both ref processors need to 'span' the entire heap as
2090   //   the regions in the collection set may be dotted around.
2091   //
2092   // * For the concurrent marking ref processor:
2093   //   * Reference discovery is enabled at initial marking.
2094   //   * Reference discovery is disabled and the discovered
2095   //     references processed etc during remarking.
2096   //   * Reference discovery is MT (see below).
2097   //   * Reference discovery requires a barrier (see below).
2098   //   * Reference processing may or may not be MT
2099   //     (depending on the value of ParallelRefProcEnabled
2100   //     and ParallelGCThreads).
2101   //   * A full GC disables reference discovery by the CM
2102   //     ref processor and abandons any entries on it's
2103   //     discovered lists.
2104   //
2105   // * For the STW processor:
2106   //   * Non MT discovery is enabled at the start of a full GC.
2107   //   * Processing and enqueueing during a full GC is non-MT.
2108   //   * During a full GC, references are processed after marking.
2109   //
2110   //   * Discovery (may or may not be MT) is enabled at the start
2111   //     of an incremental evacuation pause.
2112   //   * References are processed near the end of a STW evacuation pause.
2113   //   * For both types of GC:
2114   //     * Discovery is atomic - i.e. not concurrent.
2115   //     * Reference discovery will not need a barrier.
2116 
2117   SharedHeap::ref_processing_init();
2118   MemRegion mr = reserved_region();
2119 
2120   // Concurrent Mark ref processor
2121   _ref_processor_cm =
2122     new ReferenceProcessor(mr,    // span
2123                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2124                                 // mt processing
2125                            (int) ParallelGCThreads,
2126                                 // degree of mt processing
2127                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2128                                 // mt discovery
2129                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2130                                 // degree of mt discovery
2131                            false,
2132                                 // Reference discovery is not atomic
2133                            &_is_alive_closure_cm);
2134                                 // is alive closure
2135                                 // (for efficiency/performance)
2136 
2137   // STW ref processor
2138   _ref_processor_stw =
2139     new ReferenceProcessor(mr,    // span
2140                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2141                                 // mt processing
2142                            MAX2((int)ParallelGCThreads, 1),
2143                                 // degree of mt processing
2144                            (ParallelGCThreads > 1),
2145                                 // mt discovery
2146                            MAX2((int)ParallelGCThreads, 1),
2147                                 // degree of mt discovery
2148                            true,
2149                                 // Reference discovery is atomic
2150                            &_is_alive_closure_stw);
2151                                 // is alive closure
2152                                 // (for efficiency/performance)
2153 }
2154 
2155 size_t G1CollectedHeap::capacity() const {
2156   return _hrm.length() * HeapRegion::GrainBytes;
2157 }
2158 
2159 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2160   assert(!hr->is_continues_humongous(), "pre-condition");
2161   hr->reset_gc_time_stamp();
2162   if (hr->is_starts_humongous()) {
2163     uint first_index = hr->hrm_index() + 1;
2164     uint last_index = hr->last_hc_index();
2165     for (uint i = first_index; i < last_index; i += 1) {
2166       HeapRegion* chr = region_at(i);
2167       assert(chr->is_continues_humongous(), "sanity");
2168       chr->reset_gc_time_stamp();
2169     }
2170   }
2171 }
2172 
2173 #ifndef PRODUCT
2174 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2175 private:
2176   unsigned _gc_time_stamp;
2177   bool _failures;
2178 
2179 public:
2180   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2181     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2182 
2183   virtual bool doHeapRegion(HeapRegion* hr) {
2184     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2185     if (_gc_time_stamp != region_gc_time_stamp) {
2186       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2187                              "expected %d", HR_FORMAT_PARAMS(hr),
2188                              region_gc_time_stamp, _gc_time_stamp);
2189       _failures = true;
2190     }
2191     return false;
2192   }
2193 
2194   bool failures() { return _failures; }
2195 };
2196 
2197 void G1CollectedHeap::check_gc_time_stamps() {
2198   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2199   heap_region_iterate(&cl);
2200   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2201 }
2202 #endif // PRODUCT
2203 
2204 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2205                                                  DirtyCardQueue* into_cset_dcq,
2206                                                  bool concurrent,
2207                                                  uint worker_i) {
2208   // Clean cards in the hot card cache
2209   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2210   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2211 
2212   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2213   int n_completed_buffers = 0;
2214   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2215     n_completed_buffers++;
2216   }
2217   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2218   dcqs.clear_n_completed_buffers();
2219   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2220 }
2221 
2222 
2223 // Computes the sum of the storage used by the various regions.
2224 size_t G1CollectedHeap::used() const {
2225   return _allocator->used();
2226 }
2227 
2228 size_t G1CollectedHeap::used_unlocked() const {
2229   return _allocator->used_unlocked();
2230 }
2231 
2232 class SumUsedClosure: public HeapRegionClosure {
2233   size_t _used;
2234 public:
2235   SumUsedClosure() : _used(0) {}
2236   bool doHeapRegion(HeapRegion* r) {
2237     if (!r->is_continues_humongous()) {
2238       _used += r->used();
2239     }
2240     return false;
2241   }
2242   size_t result() { return _used; }
2243 };
2244 
2245 size_t G1CollectedHeap::recalculate_used() const {
2246   double recalculate_used_start = os::elapsedTime();
2247 
2248   SumUsedClosure blk;
2249   heap_region_iterate(&blk);
2250 
2251   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2252   return blk.result();
2253 }
2254 
2255 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2256   switch (cause) {
2257     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2258     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2259     case GCCause::_g1_humongous_allocation: return true;
2260     case GCCause::_update_allocation_context_stats_inc: return true;
2261     default:                                return false;
2262   }
2263 }
2264 
2265 #ifndef PRODUCT
2266 void G1CollectedHeap::allocate_dummy_regions() {
2267   // Let's fill up most of the region
2268   size_t word_size = HeapRegion::GrainWords - 1024;
2269   // And as a result the region we'll allocate will be humongous.
2270   guarantee(is_humongous(word_size), "sanity");
2271 
2272   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2273     // Let's use the existing mechanism for the allocation
2274     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2275                                                  AllocationContext::system());
2276     if (dummy_obj != NULL) {
2277       MemRegion mr(dummy_obj, word_size);
2278       CollectedHeap::fill_with_object(mr);
2279     } else {
2280       // If we can't allocate once, we probably cannot allocate
2281       // again. Let's get out of the loop.
2282       break;
2283     }
2284   }
2285 }
2286 #endif // !PRODUCT
2287 
2288 void G1CollectedHeap::increment_old_marking_cycles_started() {
2289   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2290     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2291     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2292     _old_marking_cycles_started, _old_marking_cycles_completed));
2293 
2294   _old_marking_cycles_started++;
2295 }
2296 
2297 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2298   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2299 
2300   // We assume that if concurrent == true, then the caller is a
2301   // concurrent thread that was joined the Suspendible Thread
2302   // Set. If there's ever a cheap way to check this, we should add an
2303   // assert here.
2304 
2305   // Given that this method is called at the end of a Full GC or of a
2306   // concurrent cycle, and those can be nested (i.e., a Full GC can
2307   // interrupt a concurrent cycle), the number of full collections
2308   // completed should be either one (in the case where there was no
2309   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2310   // behind the number of full collections started.
2311 
2312   // This is the case for the inner caller, i.e. a Full GC.
2313   assert(concurrent ||
2314          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2315          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2316          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2317                  "is inconsistent with _old_marking_cycles_completed = %u",
2318                  _old_marking_cycles_started, _old_marking_cycles_completed));
2319 
2320   // This is the case for the outer caller, i.e. the concurrent cycle.
2321   assert(!concurrent ||
2322          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2323          err_msg("for outer caller (concurrent cycle): "
2324                  "_old_marking_cycles_started = %u "
2325                  "is inconsistent with _old_marking_cycles_completed = %u",
2326                  _old_marking_cycles_started, _old_marking_cycles_completed));
2327 
2328   _old_marking_cycles_completed += 1;
2329 
2330   // We need to clear the "in_progress" flag in the CM thread before
2331   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2332   // is set) so that if a waiter requests another System.gc() it doesn't
2333   // incorrectly see that a marking cycle is still in progress.
2334   if (concurrent) {
2335     _cmThread->clear_in_progress();
2336   }
2337 
2338   // This notify_all() will ensure that a thread that called
2339   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2340   // and it's waiting for a full GC to finish will be woken up. It is
2341   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2342   FullGCCount_lock->notify_all();
2343 }
2344 
2345 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2346   _concurrent_cycle_started = true;
2347   _gc_timer_cm->register_gc_start(start_time);
2348 
2349   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2350   trace_heap_before_gc(_gc_tracer_cm);
2351 }
2352 
2353 void G1CollectedHeap::register_concurrent_cycle_end() {
2354   if (_concurrent_cycle_started) {
2355     if (_cm->has_aborted()) {
2356       _gc_tracer_cm->report_concurrent_mode_failure();
2357     }
2358 
2359     _gc_timer_cm->register_gc_end();
2360     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2361 
2362     // Clear state variables to prepare for the next concurrent cycle.
2363     _concurrent_cycle_started = false;
2364     _heap_summary_sent = false;
2365   }
2366 }
2367 
2368 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2369   if (_concurrent_cycle_started) {
2370     // This function can be called when:
2371     //  the cleanup pause is run
2372     //  the concurrent cycle is aborted before the cleanup pause.
2373     //  the concurrent cycle is aborted after the cleanup pause,
2374     //   but before the concurrent cycle end has been registered.
2375     // Make sure that we only send the heap information once.
2376     if (!_heap_summary_sent) {
2377       trace_heap_after_gc(_gc_tracer_cm);
2378       _heap_summary_sent = true;
2379     }
2380   }
2381 }
2382 
2383 G1YCType G1CollectedHeap::yc_type() {
2384   bool is_young = g1_policy()->gcs_are_young();
2385   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2386   bool is_during_mark = mark_in_progress();
2387 
2388   if (is_initial_mark) {
2389     return InitialMark;
2390   } else if (is_during_mark) {
2391     return DuringMark;
2392   } else if (is_young) {
2393     return Normal;
2394   } else {
2395     return Mixed;
2396   }
2397 }
2398 
2399 void G1CollectedHeap::collect(GCCause::Cause cause) {
2400   assert_heap_not_locked();
2401 
2402   unsigned int gc_count_before;
2403   unsigned int old_marking_count_before;
2404   unsigned int full_gc_count_before;
2405   bool retry_gc;
2406 
2407   do {
2408     retry_gc = false;
2409 
2410     {
2411       MutexLocker ml(Heap_lock);
2412 
2413       // Read the GC count while holding the Heap_lock
2414       gc_count_before = total_collections();
2415       full_gc_count_before = total_full_collections();
2416       old_marking_count_before = _old_marking_cycles_started;
2417     }
2418 
2419     if (should_do_concurrent_full_gc(cause)) {
2420       // Schedule an initial-mark evacuation pause that will start a
2421       // concurrent cycle. We're setting word_size to 0 which means that
2422       // we are not requesting a post-GC allocation.
2423       VM_G1IncCollectionPause op(gc_count_before,
2424                                  0,     /* word_size */
2425                                  true,  /* should_initiate_conc_mark */
2426                                  g1_policy()->max_pause_time_ms(),
2427                                  cause);
2428       op.set_allocation_context(AllocationContext::current());
2429 
2430       VMThread::execute(&op);
2431       if (!op.pause_succeeded()) {
2432         if (old_marking_count_before == _old_marking_cycles_started) {
2433           retry_gc = op.should_retry_gc();
2434         } else {
2435           // A Full GC happened while we were trying to schedule the
2436           // initial-mark GC. No point in starting a new cycle given
2437           // that the whole heap was collected anyway.
2438         }
2439 
2440         if (retry_gc) {
2441           if (GC_locker::is_active_and_needs_gc()) {
2442             GC_locker::stall_until_clear();
2443           }
2444         }
2445       }
2446     } else {
2447       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2448           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2449 
2450         // Schedule a standard evacuation pause. We're setting word_size
2451         // to 0 which means that we are not requesting a post-GC allocation.
2452         VM_G1IncCollectionPause op(gc_count_before,
2453                                    0,     /* word_size */
2454                                    false, /* should_initiate_conc_mark */
2455                                    g1_policy()->max_pause_time_ms(),
2456                                    cause);
2457         VMThread::execute(&op);
2458       } else {
2459         // Schedule a Full GC.
2460         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2461         VMThread::execute(&op);
2462       }
2463     }
2464   } while (retry_gc);
2465 }
2466 
2467 bool G1CollectedHeap::is_in(const void* p) const {
2468   if (_hrm.reserved().contains(p)) {
2469     // Given that we know that p is in the reserved space,
2470     // heap_region_containing_raw() should successfully
2471     // return the containing region.
2472     HeapRegion* hr = heap_region_containing_raw(p);
2473     return hr->is_in(p);
2474   } else {
2475     return false;
2476   }
2477 }
2478 
2479 #ifdef ASSERT
2480 bool G1CollectedHeap::is_in_exact(const void* p) const {
2481   bool contains = reserved_region().contains(p);
2482   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2483   if (contains && available) {
2484     return true;
2485   } else {
2486     return false;
2487   }
2488 }
2489 #endif
2490 
2491 // Iteration functions.
2492 
2493 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2494 
2495 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2496   ExtendedOopClosure* _cl;
2497 public:
2498   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2499   bool doHeapRegion(HeapRegion* r) {
2500     if (!r->is_continues_humongous()) {
2501       r->oop_iterate(_cl);
2502     }
2503     return false;
2504   }
2505 };
2506 
2507 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2508   IterateOopClosureRegionClosure blk(cl);
2509   heap_region_iterate(&blk);
2510 }
2511 
2512 // Iterates an ObjectClosure over all objects within a HeapRegion.
2513 
2514 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2515   ObjectClosure* _cl;
2516 public:
2517   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2518   bool doHeapRegion(HeapRegion* r) {
2519     if (!r->is_continues_humongous()) {
2520       r->object_iterate(_cl);
2521     }
2522     return false;
2523   }
2524 };
2525 
2526 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2527   IterateObjectClosureRegionClosure blk(cl);
2528   heap_region_iterate(&blk);
2529 }
2530 
2531 // Calls a SpaceClosure on a HeapRegion.
2532 
2533 class SpaceClosureRegionClosure: public HeapRegionClosure {
2534   SpaceClosure* _cl;
2535 public:
2536   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2537   bool doHeapRegion(HeapRegion* r) {
2538     _cl->do_space(r);
2539     return false;
2540   }
2541 };
2542 
2543 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2544   SpaceClosureRegionClosure blk(cl);
2545   heap_region_iterate(&blk);
2546 }
2547 
2548 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2549   _hrm.iterate(cl);
2550 }
2551 
2552 void
2553 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2554                                          uint worker_id,
2555                                          HeapRegionClaimer *hrclaimer) const {
2556   _hrm.par_iterate(cl, worker_id, hrclaimer);
2557 }
2558 
2559 // Clear the cached CSet starting regions and (more importantly)
2560 // the time stamps. Called when we reset the GC time stamp.
2561 void G1CollectedHeap::clear_cset_start_regions() {
2562   assert(_worker_cset_start_region != NULL, "sanity");
2563   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2564 
2565   int n_queues = MAX2((int)ParallelGCThreads, 1);
2566   for (int i = 0; i < n_queues; i++) {
2567     _worker_cset_start_region[i] = NULL;
2568     _worker_cset_start_region_time_stamp[i] = 0;
2569   }
2570 }
2571 
2572 // Given the id of a worker, obtain or calculate a suitable
2573 // starting region for iterating over the current collection set.
2574 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2575   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2576 
2577   HeapRegion* result = NULL;
2578   unsigned gc_time_stamp = get_gc_time_stamp();
2579 
2580   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2581     // Cached starting region for current worker was set
2582     // during the current pause - so it's valid.
2583     // Note: the cached starting heap region may be NULL
2584     // (when the collection set is empty).
2585     result = _worker_cset_start_region[worker_i];
2586     assert(result == NULL || result->in_collection_set(), "sanity");
2587     return result;
2588   }
2589 
2590   // The cached entry was not valid so let's calculate
2591   // a suitable starting heap region for this worker.
2592 
2593   // We want the parallel threads to start their collection
2594   // set iteration at different collection set regions to
2595   // avoid contention.
2596   // If we have:
2597   //          n collection set regions
2598   //          p threads
2599   // Then thread t will start at region floor ((t * n) / p)
2600 
2601   result = g1_policy()->collection_set();
2602   uint cs_size = g1_policy()->cset_region_length();
2603   uint active_workers = workers()->active_workers();
2604   assert(UseDynamicNumberOfGCThreads ||
2605            active_workers == workers()->total_workers(),
2606            "Unless dynamic should use total workers");
2607 
2608   uint end_ind   = (cs_size * worker_i) / active_workers;
2609   uint start_ind = 0;
2610 
2611   if (worker_i > 0 &&
2612       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2613     // Previous workers starting region is valid
2614     // so let's iterate from there
2615     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2616     result = _worker_cset_start_region[worker_i - 1];
2617   }
2618 
2619   for (uint i = start_ind; i < end_ind; i++) {
2620     result = result->next_in_collection_set();
2621   }
2622 
2623   // Note: the calculated starting heap region may be NULL
2624   // (when the collection set is empty).
2625   assert(result == NULL || result->in_collection_set(), "sanity");
2626   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2627          "should be updated only once per pause");
2628   _worker_cset_start_region[worker_i] = result;
2629   OrderAccess::storestore();
2630   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2631   return result;
2632 }
2633 
2634 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2635   HeapRegion* r = g1_policy()->collection_set();
2636   while (r != NULL) {
2637     HeapRegion* next = r->next_in_collection_set();
2638     if (cl->doHeapRegion(r)) {
2639       cl->incomplete();
2640       return;
2641     }
2642     r = next;
2643   }
2644 }
2645 
2646 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2647                                                   HeapRegionClosure *cl) {
2648   if (r == NULL) {
2649     // The CSet is empty so there's nothing to do.
2650     return;
2651   }
2652 
2653   assert(r->in_collection_set(),
2654          "Start region must be a member of the collection set.");
2655   HeapRegion* cur = r;
2656   while (cur != NULL) {
2657     HeapRegion* next = cur->next_in_collection_set();
2658     if (cl->doHeapRegion(cur) && false) {
2659       cl->incomplete();
2660       return;
2661     }
2662     cur = next;
2663   }
2664   cur = g1_policy()->collection_set();
2665   while (cur != r) {
2666     HeapRegion* next = cur->next_in_collection_set();
2667     if (cl->doHeapRegion(cur) && false) {
2668       cl->incomplete();
2669       return;
2670     }
2671     cur = next;
2672   }
2673 }
2674 
2675 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2676   HeapRegion* result = _hrm.next_region_in_heap(from);
2677   while (result != NULL && result->is_humongous()) {
2678     result = _hrm.next_region_in_heap(result);
2679   }
2680   return result;
2681 }
2682 
2683 Space* G1CollectedHeap::space_containing(const void* addr) const {
2684   return heap_region_containing(addr);
2685 }
2686 
2687 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2688   Space* sp = space_containing(addr);
2689   return sp->block_start(addr);
2690 }
2691 
2692 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2693   Space* sp = space_containing(addr);
2694   return sp->block_size(addr);
2695 }
2696 
2697 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2698   Space* sp = space_containing(addr);
2699   return sp->block_is_obj(addr);
2700 }
2701 
2702 bool G1CollectedHeap::supports_tlab_allocation() const {
2703   return true;
2704 }
2705 
2706 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2707   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2708 }
2709 
2710 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2711   return young_list()->eden_used_bytes();
2712 }
2713 
2714 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2715 // must be smaller than the humongous object limit.
2716 size_t G1CollectedHeap::max_tlab_size() const {
2717   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2718 }
2719 
2720 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2721   // Return the remaining space in the cur alloc region, but not less than
2722   // the min TLAB size.
2723 
2724   // Also, this value can be at most the humongous object threshold,
2725   // since we can't allow tlabs to grow big enough to accommodate
2726   // humongous objects.
2727 
2728   HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2729   size_t max_tlab = max_tlab_size() * wordSize;
2730   if (hr == NULL) {
2731     return max_tlab;
2732   } else {
2733     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2734   }
2735 }
2736 
2737 size_t G1CollectedHeap::max_capacity() const {
2738   return _hrm.reserved().byte_size();
2739 }
2740 
2741 jlong G1CollectedHeap::millis_since_last_gc() {
2742   // assert(false, "NYI");
2743   return 0;
2744 }
2745 
2746 void G1CollectedHeap::prepare_for_verify() {
2747   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2748     ensure_parsability(false);
2749   }
2750   g1_rem_set()->prepare_for_verify();
2751 }
2752 
2753 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2754                                               VerifyOption vo) {
2755   switch (vo) {
2756   case VerifyOption_G1UsePrevMarking:
2757     return hr->obj_allocated_since_prev_marking(obj);
2758   case VerifyOption_G1UseNextMarking:
2759     return hr->obj_allocated_since_next_marking(obj);
2760   case VerifyOption_G1UseMarkWord:
2761     return false;
2762   default:
2763     ShouldNotReachHere();
2764   }
2765   return false; // keep some compilers happy
2766 }
2767 
2768 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2769   switch (vo) {
2770   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2771   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2772   case VerifyOption_G1UseMarkWord:    return NULL;
2773   default:                            ShouldNotReachHere();
2774   }
2775   return NULL; // keep some compilers happy
2776 }
2777 
2778 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2779   switch (vo) {
2780   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2781   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2782   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2783   default:                            ShouldNotReachHere();
2784   }
2785   return false; // keep some compilers happy
2786 }
2787 
2788 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2789   switch (vo) {
2790   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2791   case VerifyOption_G1UseNextMarking: return "NTAMS";
2792   case VerifyOption_G1UseMarkWord:    return "NONE";
2793   default:                            ShouldNotReachHere();
2794   }
2795   return NULL; // keep some compilers happy
2796 }
2797 
2798 class VerifyRootsClosure: public OopClosure {
2799 private:
2800   G1CollectedHeap* _g1h;
2801   VerifyOption     _vo;
2802   bool             _failures;
2803 public:
2804   // _vo == UsePrevMarking -> use "prev" marking information,
2805   // _vo == UseNextMarking -> use "next" marking information,
2806   // _vo == UseMarkWord    -> use mark word from object header.
2807   VerifyRootsClosure(VerifyOption vo) :
2808     _g1h(G1CollectedHeap::heap()),
2809     _vo(vo),
2810     _failures(false) { }
2811 
2812   bool failures() { return _failures; }
2813 
2814   template <class T> void do_oop_nv(T* p) {
2815     T heap_oop = oopDesc::load_heap_oop(p);
2816     if (!oopDesc::is_null(heap_oop)) {
2817       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2818       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2819         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2820                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2821         if (_vo == VerifyOption_G1UseMarkWord) {
2822           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2823         }
2824         obj->print_on(gclog_or_tty);
2825         _failures = true;
2826       }
2827     }
2828   }
2829 
2830   void do_oop(oop* p)       { do_oop_nv(p); }
2831   void do_oop(narrowOop* p) { do_oop_nv(p); }
2832 };
2833 
2834 class G1VerifyCodeRootOopClosure: public OopClosure {
2835   G1CollectedHeap* _g1h;
2836   OopClosure* _root_cl;
2837   nmethod* _nm;
2838   VerifyOption _vo;
2839   bool _failures;
2840 
2841   template <class T> void do_oop_work(T* p) {
2842     // First verify that this root is live
2843     _root_cl->do_oop(p);
2844 
2845     if (!G1VerifyHeapRegionCodeRoots) {
2846       // We're not verifying the code roots attached to heap region.
2847       return;
2848     }
2849 
2850     // Don't check the code roots during marking verification in a full GC
2851     if (_vo == VerifyOption_G1UseMarkWord) {
2852       return;
2853     }
2854 
2855     // Now verify that the current nmethod (which contains p) is
2856     // in the code root list of the heap region containing the
2857     // object referenced by p.
2858 
2859     T heap_oop = oopDesc::load_heap_oop(p);
2860     if (!oopDesc::is_null(heap_oop)) {
2861       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2862 
2863       // Now fetch the region containing the object
2864       HeapRegion* hr = _g1h->heap_region_containing(obj);
2865       HeapRegionRemSet* hrrs = hr->rem_set();
2866       // Verify that the strong code root list for this region
2867       // contains the nmethod
2868       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2869         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2870                               "from nmethod "PTR_FORMAT" not in strong "
2871                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2872                               p, _nm, hr->bottom(), hr->end());
2873         _failures = true;
2874       }
2875     }
2876   }
2877 
2878 public:
2879   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2880     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2881 
2882   void do_oop(oop* p) { do_oop_work(p); }
2883   void do_oop(narrowOop* p) { do_oop_work(p); }
2884 
2885   void set_nmethod(nmethod* nm) { _nm = nm; }
2886   bool failures() { return _failures; }
2887 };
2888 
2889 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2890   G1VerifyCodeRootOopClosure* _oop_cl;
2891 
2892 public:
2893   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2894     _oop_cl(oop_cl) {}
2895 
2896   void do_code_blob(CodeBlob* cb) {
2897     nmethod* nm = cb->as_nmethod_or_null();
2898     if (nm != NULL) {
2899       _oop_cl->set_nmethod(nm);
2900       nm->oops_do(_oop_cl);
2901     }
2902   }
2903 };
2904 
2905 class YoungRefCounterClosure : public OopClosure {
2906   G1CollectedHeap* _g1h;
2907   int              _count;
2908  public:
2909   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2910   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2911   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2912 
2913   int count() { return _count; }
2914   void reset_count() { _count = 0; };
2915 };
2916 
2917 class VerifyKlassClosure: public KlassClosure {
2918   YoungRefCounterClosure _young_ref_counter_closure;
2919   OopClosure *_oop_closure;
2920  public:
2921   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2922   void do_klass(Klass* k) {
2923     k->oops_do(_oop_closure);
2924 
2925     _young_ref_counter_closure.reset_count();
2926     k->oops_do(&_young_ref_counter_closure);
2927     if (_young_ref_counter_closure.count() > 0) {
2928       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2929     }
2930   }
2931 };
2932 
2933 class VerifyLivenessOopClosure: public OopClosure {
2934   G1CollectedHeap* _g1h;
2935   VerifyOption _vo;
2936 public:
2937   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2938     _g1h(g1h), _vo(vo)
2939   { }
2940   void do_oop(narrowOop *p) { do_oop_work(p); }
2941   void do_oop(      oop *p) { do_oop_work(p); }
2942 
2943   template <class T> void do_oop_work(T *p) {
2944     oop obj = oopDesc::load_decode_heap_oop(p);
2945     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2946               "Dead object referenced by a not dead object");
2947   }
2948 };
2949 
2950 class VerifyObjsInRegionClosure: public ObjectClosure {
2951 private:
2952   G1CollectedHeap* _g1h;
2953   size_t _live_bytes;
2954   HeapRegion *_hr;
2955   VerifyOption _vo;
2956 public:
2957   // _vo == UsePrevMarking -> use "prev" marking information,
2958   // _vo == UseNextMarking -> use "next" marking information,
2959   // _vo == UseMarkWord    -> use mark word from object header.
2960   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2961     : _live_bytes(0), _hr(hr), _vo(vo) {
2962     _g1h = G1CollectedHeap::heap();
2963   }
2964   void do_object(oop o) {
2965     VerifyLivenessOopClosure isLive(_g1h, _vo);
2966     assert(o != NULL, "Huh?");
2967     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2968       // If the object is alive according to the mark word,
2969       // then verify that the marking information agrees.
2970       // Note we can't verify the contra-positive of the
2971       // above: if the object is dead (according to the mark
2972       // word), it may not be marked, or may have been marked
2973       // but has since became dead, or may have been allocated
2974       // since the last marking.
2975       if (_vo == VerifyOption_G1UseMarkWord) {
2976         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2977       }
2978 
2979       o->oop_iterate_no_header(&isLive);
2980       if (!_hr->obj_allocated_since_prev_marking(o)) {
2981         size_t obj_size = o->size();    // Make sure we don't overflow
2982         _live_bytes += (obj_size * HeapWordSize);
2983       }
2984     }
2985   }
2986   size_t live_bytes() { return _live_bytes; }
2987 };
2988 
2989 class PrintObjsInRegionClosure : public ObjectClosure {
2990   HeapRegion *_hr;
2991   G1CollectedHeap *_g1;
2992 public:
2993   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2994     _g1 = G1CollectedHeap::heap();
2995   };
2996 
2997   void do_object(oop o) {
2998     if (o != NULL) {
2999       HeapWord *start = (HeapWord *) o;
3000       size_t word_sz = o->size();
3001       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3002                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3003                           (void*) o, word_sz,
3004                           _g1->isMarkedPrev(o),
3005                           _g1->isMarkedNext(o),
3006                           _hr->obj_allocated_since_prev_marking(o));
3007       HeapWord *end = start + word_sz;
3008       HeapWord *cur;
3009       int *val;
3010       for (cur = start; cur < end; cur++) {
3011         val = (int *) cur;
3012         gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3013       }
3014     }
3015   }
3016 };
3017 
3018 class VerifyRegionClosure: public HeapRegionClosure {
3019 private:
3020   bool             _par;
3021   VerifyOption     _vo;
3022   bool             _failures;
3023 public:
3024   // _vo == UsePrevMarking -> use "prev" marking information,
3025   // _vo == UseNextMarking -> use "next" marking information,
3026   // _vo == UseMarkWord    -> use mark word from object header.
3027   VerifyRegionClosure(bool par, VerifyOption vo)
3028     : _par(par),
3029       _vo(vo),
3030       _failures(false) {}
3031 
3032   bool failures() {
3033     return _failures;
3034   }
3035 
3036   bool doHeapRegion(HeapRegion* r) {
3037     if (!r->is_continues_humongous()) {
3038       bool failures = false;
3039       r->verify(_vo, &failures);
3040       if (failures) {
3041         _failures = true;
3042       } else {
3043         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3044         r->object_iterate(&not_dead_yet_cl);
3045         if (_vo != VerifyOption_G1UseNextMarking) {
3046           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3047             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3048                                    "max_live_bytes "SIZE_FORMAT" "
3049                                    "< calculated "SIZE_FORMAT,
3050                                    r->bottom(), r->end(),
3051                                    r->max_live_bytes(),
3052                                  not_dead_yet_cl.live_bytes());
3053             _failures = true;
3054           }
3055         } else {
3056           // When vo == UseNextMarking we cannot currently do a sanity
3057           // check on the live bytes as the calculation has not been
3058           // finalized yet.
3059         }
3060       }
3061     }
3062     return false; // stop the region iteration if we hit a failure
3063   }
3064 };
3065 
3066 // This is the task used for parallel verification of the heap regions
3067 
3068 class G1ParVerifyTask: public AbstractGangTask {
3069 private:
3070   G1CollectedHeap*  _g1h;
3071   VerifyOption      _vo;
3072   bool              _failures;
3073   HeapRegionClaimer _hrclaimer;
3074 
3075 public:
3076   // _vo == UsePrevMarking -> use "prev" marking information,
3077   // _vo == UseNextMarking -> use "next" marking information,
3078   // _vo == UseMarkWord    -> use mark word from object header.
3079   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3080       AbstractGangTask("Parallel verify task"),
3081       _g1h(g1h),
3082       _vo(vo),
3083       _failures(false),
3084       _hrclaimer(g1h->workers()->active_workers()) {}
3085 
3086   bool failures() {
3087     return _failures;
3088   }
3089 
3090   void work(uint worker_id) {
3091     HandleMark hm;
3092     VerifyRegionClosure blk(true, _vo);
3093     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3094     if (blk.failures()) {
3095       _failures = true;
3096     }
3097   }
3098 };
3099 
3100 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3101   if (SafepointSynchronize::is_at_safepoint()) {
3102     assert(Thread::current()->is_VM_thread(),
3103            "Expected to be executed serially by the VM thread at this point");
3104 
3105     if (!silent) { gclog_or_tty->print("Roots "); }
3106     VerifyRootsClosure rootsCl(vo);
3107     VerifyKlassClosure klassCl(this, &rootsCl);
3108     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3109 
3110     // We apply the relevant closures to all the oops in the
3111     // system dictionary, class loader data graph, the string table
3112     // and the nmethods in the code cache.
3113     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3114     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3115 
3116     process_all_roots(true,            // activate StrongRootsScope
3117                       SO_AllCodeCache, // roots scanning options
3118                       &rootsCl,
3119                       &cldCl,
3120                       &blobsCl);
3121 
3122     bool failures = rootsCl.failures() || codeRootsCl.failures();
3123 
3124     if (vo != VerifyOption_G1UseMarkWord) {
3125       // If we're verifying during a full GC then the region sets
3126       // will have been torn down at the start of the GC. Therefore
3127       // verifying the region sets will fail. So we only verify
3128       // the region sets when not in a full GC.
3129       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3130       verify_region_sets();
3131     }
3132 
3133     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3134     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3135 
3136       G1ParVerifyTask task(this, vo);
3137       assert(UseDynamicNumberOfGCThreads ||
3138         workers()->active_workers() == workers()->total_workers(),
3139         "If not dynamic should be using all the workers");
3140       int n_workers = workers()->active_workers();
3141       set_par_threads(n_workers);
3142       workers()->run_task(&task);
3143       set_par_threads(0);
3144       if (task.failures()) {
3145         failures = true;
3146       }
3147 
3148     } else {
3149       VerifyRegionClosure blk(false, vo);
3150       heap_region_iterate(&blk);
3151       if (blk.failures()) {
3152         failures = true;
3153       }
3154     }
3155     if (!silent) gclog_or_tty->print("RemSet ");
3156     rem_set()->verify();
3157 
3158     if (G1StringDedup::is_enabled()) {
3159       if (!silent) gclog_or_tty->print("StrDedup ");
3160       G1StringDedup::verify();
3161     }
3162 
3163     if (failures) {
3164       gclog_or_tty->print_cr("Heap:");
3165       // It helps to have the per-region information in the output to
3166       // help us track down what went wrong. This is why we call
3167       // print_extended_on() instead of print_on().
3168       print_extended_on(gclog_or_tty);
3169       gclog_or_tty->cr();
3170 #ifndef PRODUCT
3171       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3172         concurrent_mark()->print_reachable("at-verification-failure",
3173                                            vo, false /* all */);
3174       }
3175 #endif
3176       gclog_or_tty->flush();
3177     }
3178     guarantee(!failures, "there should not have been any failures");
3179   } else {
3180     if (!silent) {
3181       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3182       if (G1StringDedup::is_enabled()) {
3183         gclog_or_tty->print(", StrDedup");
3184       }
3185       gclog_or_tty->print(") ");
3186     }
3187   }
3188 }
3189 
3190 void G1CollectedHeap::verify(bool silent) {
3191   verify(silent, VerifyOption_G1UsePrevMarking);
3192 }
3193 
3194 double G1CollectedHeap::verify(bool guard, const char* msg) {
3195   double verify_time_ms = 0.0;
3196 
3197   if (guard && total_collections() >= VerifyGCStartAt) {
3198     double verify_start = os::elapsedTime();
3199     HandleMark hm;  // Discard invalid handles created during verification
3200     prepare_for_verify();
3201     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3202     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3203   }
3204 
3205   return verify_time_ms;
3206 }
3207 
3208 void G1CollectedHeap::verify_before_gc() {
3209   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3210   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3211 }
3212 
3213 void G1CollectedHeap::verify_after_gc() {
3214   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3215   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3216 }
3217 
3218 class PrintRegionClosure: public HeapRegionClosure {
3219   outputStream* _st;
3220 public:
3221   PrintRegionClosure(outputStream* st) : _st(st) {}
3222   bool doHeapRegion(HeapRegion* r) {
3223     r->print_on(_st);
3224     return false;
3225   }
3226 };
3227 
3228 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3229                                        const HeapRegion* hr,
3230                                        const VerifyOption vo) const {
3231   switch (vo) {
3232   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3233   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3234   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3235   default:                            ShouldNotReachHere();
3236   }
3237   return false; // keep some compilers happy
3238 }
3239 
3240 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3241                                        const VerifyOption vo) const {
3242   switch (vo) {
3243   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3244   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3245   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3246   default:                            ShouldNotReachHere();
3247   }
3248   return false; // keep some compilers happy
3249 }
3250 
3251 void G1CollectedHeap::print_on(outputStream* st) const {
3252   st->print(" %-20s", "garbage-first heap");
3253   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3254             capacity()/K, used_unlocked()/K);
3255   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3256             _hrm.reserved().start(),
3257             _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3258             _hrm.reserved().end());
3259   st->cr();
3260   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3261   uint young_regions = _young_list->length();
3262   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3263             (size_t) young_regions * HeapRegion::GrainBytes / K);
3264   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3265   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3266             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3267   st->cr();
3268   MetaspaceAux::print_on(st);
3269 }
3270 
3271 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3272   print_on(st);
3273 
3274   // Print the per-region information.
3275   st->cr();
3276   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3277                "HS=humongous(starts), HC=humongous(continues), "
3278                "CS=collection set, F=free, TS=gc time stamp, "
3279                "PTAMS=previous top-at-mark-start, "
3280                "NTAMS=next top-at-mark-start)");
3281   PrintRegionClosure blk(st);
3282   heap_region_iterate(&blk);
3283 }
3284 
3285 void G1CollectedHeap::print_on_error(outputStream* st) const {
3286   this->CollectedHeap::print_on_error(st);
3287 
3288   if (_cm != NULL) {
3289     st->cr();
3290     _cm->print_on_error(st);
3291   }
3292 }
3293 
3294 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3295   workers()->print_worker_threads_on(st);
3296   _cmThread->print_on(st);
3297   st->cr();
3298   _cm->print_worker_threads_on(st);
3299   _cg1r->print_worker_threads_on(st);
3300   if (G1StringDedup::is_enabled()) {
3301     G1StringDedup::print_worker_threads_on(st);
3302   }
3303 }
3304 
3305 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3306   workers()->threads_do(tc);
3307   tc->do_thread(_cmThread);
3308   _cg1r->threads_do(tc);
3309   if (G1StringDedup::is_enabled()) {
3310     G1StringDedup::threads_do(tc);
3311   }
3312 }
3313 
3314 void G1CollectedHeap::print_tracing_info() const {
3315   // We'll overload this to mean "trace GC pause statistics."
3316   if (TraceYoungGenTime || TraceOldGenTime) {
3317     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3318     // to that.
3319     g1_policy()->print_tracing_info();
3320   }
3321   if (G1SummarizeRSetStats) {
3322     g1_rem_set()->print_summary_info();
3323   }
3324   if (G1SummarizeConcMark) {
3325     concurrent_mark()->print_summary_info();
3326   }
3327   g1_policy()->print_yg_surv_rate_info();
3328   SpecializationStats::print();
3329 }
3330 
3331 #ifndef PRODUCT
3332 // Helpful for debugging RSet issues.
3333 
3334 class PrintRSetsClosure : public HeapRegionClosure {
3335 private:
3336   const char* _msg;
3337   size_t _occupied_sum;
3338 
3339 public:
3340   bool doHeapRegion(HeapRegion* r) {
3341     HeapRegionRemSet* hrrs = r->rem_set();
3342     size_t occupied = hrrs->occupied();
3343     _occupied_sum += occupied;
3344 
3345     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3346                            HR_FORMAT_PARAMS(r));
3347     if (occupied == 0) {
3348       gclog_or_tty->print_cr("  RSet is empty");
3349     } else {
3350       hrrs->print();
3351     }
3352     gclog_or_tty->print_cr("----------");
3353     return false;
3354   }
3355 
3356   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3357     gclog_or_tty->cr();
3358     gclog_or_tty->print_cr("========================================");
3359     gclog_or_tty->print_cr("%s", msg);
3360     gclog_or_tty->cr();
3361   }
3362 
3363   ~PrintRSetsClosure() {
3364     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3365     gclog_or_tty->print_cr("========================================");
3366     gclog_or_tty->cr();
3367   }
3368 };
3369 
3370 void G1CollectedHeap::print_cset_rsets() {
3371   PrintRSetsClosure cl("Printing CSet RSets");
3372   collection_set_iterate(&cl);
3373 }
3374 
3375 void G1CollectedHeap::print_all_rsets() {
3376   PrintRSetsClosure cl("Printing All RSets");;
3377   heap_region_iterate(&cl);
3378 }
3379 #endif // PRODUCT
3380 
3381 G1CollectedHeap* G1CollectedHeap::heap() {
3382   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3383          "not a garbage-first heap");
3384   return _g1h;
3385 }
3386 
3387 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3388   // always_do_update_barrier = false;
3389   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3390   // Fill TLAB's and such
3391   accumulate_statistics_all_tlabs();
3392   ensure_parsability(true);
3393 
3394   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3395       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3396     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3397   }
3398 }
3399 
3400 void G1CollectedHeap::gc_epilogue(bool full) {
3401 
3402   if (G1SummarizeRSetStats &&
3403       (G1SummarizeRSetStatsPeriod > 0) &&
3404       // we are at the end of the GC. Total collections has already been increased.
3405       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3406     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3407   }
3408 
3409   // FIXME: what is this about?
3410   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3411   // is set.
3412   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3413                         "derived pointer present"));
3414   // always_do_update_barrier = true;
3415 
3416   resize_all_tlabs();
3417   allocation_context_stats().update(full);
3418 
3419   // We have just completed a GC. Update the soft reference
3420   // policy with the new heap occupancy
3421   Universe::update_heap_info_at_gc();
3422 }
3423 
3424 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3425                                                unsigned int gc_count_before,
3426                                                bool* succeeded,
3427                                                GCCause::Cause gc_cause) {
3428   assert_heap_not_locked_and_not_at_safepoint();
3429   g1_policy()->record_stop_world_start();
3430   VM_G1IncCollectionPause op(gc_count_before,
3431                              word_size,
3432                              false, /* should_initiate_conc_mark */
3433                              g1_policy()->max_pause_time_ms(),
3434                              gc_cause);
3435 
3436   op.set_allocation_context(AllocationContext::current());
3437   VMThread::execute(&op);
3438 
3439   HeapWord* result = op.result();
3440   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3441   assert(result == NULL || ret_succeeded,
3442          "the result should be NULL if the VM did not succeed");
3443   *succeeded = ret_succeeded;
3444 
3445   assert_heap_not_locked();
3446   return result;
3447 }
3448 
3449 void
3450 G1CollectedHeap::doConcurrentMark() {
3451   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3452   if (!_cmThread->in_progress()) {
3453     _cmThread->set_started();
3454     CGC_lock->notify();
3455   }
3456 }
3457 
3458 size_t G1CollectedHeap::pending_card_num() {
3459   size_t extra_cards = 0;
3460   JavaThread *curr = Threads::first();
3461   while (curr != NULL) {
3462     DirtyCardQueue& dcq = curr->dirty_card_queue();
3463     extra_cards += dcq.size();
3464     curr = curr->next();
3465   }
3466   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3467   size_t buffer_size = dcqs.buffer_size();
3468   size_t buffer_num = dcqs.completed_buffers_num();
3469 
3470   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3471   // in bytes - not the number of 'entries'. We need to convert
3472   // into a number of cards.
3473   return (buffer_size * buffer_num + extra_cards) / oopSize;
3474 }
3475 
3476 size_t G1CollectedHeap::cards_scanned() {
3477   return g1_rem_set()->cardsScanned();
3478 }
3479 
3480 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3481   HeapRegion* region = region_at(index);
3482   assert(region->is_starts_humongous(), "Must start a humongous object");
3483   return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3484 }
3485 
3486 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3487  private:
3488   size_t _total_humongous;
3489   size_t _candidate_humongous;
3490  public:
3491   RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3492   }
3493 
3494   virtual bool doHeapRegion(HeapRegion* r) {
3495     if (!r->is_starts_humongous()) {
3496       return false;
3497     }
3498     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3499 
3500     uint region_idx = r->hrm_index();
3501     bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3502     // Is_candidate already filters out humongous regions with some remembered set.
3503     // This will not lead to humongous object that we mistakenly keep alive because
3504     // during young collection the remembered sets will only be added to.
3505     if (is_candidate) {
3506       g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3507       _candidate_humongous++;
3508     }
3509     _total_humongous++;
3510 
3511     return false;
3512   }
3513 
3514   size_t total_humongous() const { return _total_humongous; }
3515   size_t candidate_humongous() const { return _candidate_humongous; }
3516 };
3517 
3518 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3519   if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3520     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3521     return;
3522   }
3523 
3524   RegisterHumongousWithInCSetFastTestClosure cl;
3525   heap_region_iterate(&cl);
3526   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3527                                                                   cl.candidate_humongous());
3528   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3529 
3530   if (_has_humongous_reclaim_candidates || G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
3531     clear_humongous_is_live_table();
3532   }
3533 }
3534 
3535 void
3536 G1CollectedHeap::setup_surviving_young_words() {
3537   assert(_surviving_young_words == NULL, "pre-condition");
3538   uint array_length = g1_policy()->young_cset_region_length();
3539   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3540   if (_surviving_young_words == NULL) {
3541     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3542                           "Not enough space for young surv words summary.");
3543   }
3544   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3545 #ifdef ASSERT
3546   for (uint i = 0;  i < array_length; ++i) {
3547     assert( _surviving_young_words[i] == 0, "memset above" );
3548   }
3549 #endif // !ASSERT
3550 }
3551 
3552 void
3553 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3554   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3555   uint array_length = g1_policy()->young_cset_region_length();
3556   for (uint i = 0; i < array_length; ++i) {
3557     _surviving_young_words[i] += surv_young_words[i];
3558   }
3559 }
3560 
3561 void
3562 G1CollectedHeap::cleanup_surviving_young_words() {
3563   guarantee( _surviving_young_words != NULL, "pre-condition" );
3564   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3565   _surviving_young_words = NULL;
3566 }
3567 
3568 #ifdef ASSERT
3569 class VerifyCSetClosure: public HeapRegionClosure {
3570 public:
3571   bool doHeapRegion(HeapRegion* hr) {
3572     // Here we check that the CSet region's RSet is ready for parallel
3573     // iteration. The fields that we'll verify are only manipulated
3574     // when the region is part of a CSet and is collected. Afterwards,
3575     // we reset these fields when we clear the region's RSet (when the
3576     // region is freed) so they are ready when the region is
3577     // re-allocated. The only exception to this is if there's an
3578     // evacuation failure and instead of freeing the region we leave
3579     // it in the heap. In that case, we reset these fields during
3580     // evacuation failure handling.
3581     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3582 
3583     // Here's a good place to add any other checks we'd like to
3584     // perform on CSet regions.
3585     return false;
3586   }
3587 };
3588 #endif // ASSERT
3589 
3590 #if TASKQUEUE_STATS
3591 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3592   st->print_raw_cr("GC Task Stats");
3593   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3594   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3595 }
3596 
3597 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3598   print_taskqueue_stats_hdr(st);
3599 
3600   TaskQueueStats totals;
3601   const int n = workers()->total_workers();
3602   for (int i = 0; i < n; ++i) {
3603     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3604     totals += task_queue(i)->stats;
3605   }
3606   st->print_raw("tot "); totals.print(st); st->cr();
3607 
3608   DEBUG_ONLY(totals.verify());
3609 }
3610 
3611 void G1CollectedHeap::reset_taskqueue_stats() {
3612   const int n = workers()->total_workers();
3613   for (int i = 0; i < n; ++i) {
3614     task_queue(i)->stats.reset();
3615   }
3616 }
3617 #endif // TASKQUEUE_STATS
3618 
3619 void G1CollectedHeap::log_gc_header() {
3620   if (!G1Log::fine()) {
3621     return;
3622   }
3623 
3624   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3625 
3626   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3627     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3628     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3629 
3630   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3631 }
3632 
3633 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3634   if (!G1Log::fine()) {
3635     return;
3636   }
3637 
3638   if (G1Log::finer()) {
3639     if (evacuation_failed()) {
3640       gclog_or_tty->print(" (to-space exhausted)");
3641     }
3642     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3643     g1_policy()->phase_times()->note_gc_end();
3644     g1_policy()->phase_times()->print(pause_time_sec);
3645     g1_policy()->print_detailed_heap_transition();
3646   } else {
3647     if (evacuation_failed()) {
3648       gclog_or_tty->print("--");
3649     }
3650     g1_policy()->print_heap_transition();
3651     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3652   }
3653   gclog_or_tty->flush();
3654 }
3655 
3656 bool
3657 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3658   assert_at_safepoint(true /* should_be_vm_thread */);
3659   guarantee(!is_gc_active(), "collection is not reentrant");
3660 
3661   if (GC_locker::check_active_before_gc()) {
3662     return false;
3663   }
3664 
3665   _gc_timer_stw->register_gc_start();
3666 
3667   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3668 
3669   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3670   ResourceMark rm;
3671 
3672   print_heap_before_gc();
3673   trace_heap_before_gc(_gc_tracer_stw);
3674 
3675   verify_region_sets_optional();
3676   verify_dirty_young_regions();
3677 
3678   // This call will decide whether this pause is an initial-mark
3679   // pause. If it is, during_initial_mark_pause() will return true
3680   // for the duration of this pause.
3681   g1_policy()->decide_on_conc_mark_initiation();
3682 
3683   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3684   assert(!g1_policy()->during_initial_mark_pause() ||
3685           g1_policy()->gcs_are_young(), "sanity");
3686 
3687   // We also do not allow mixed GCs during marking.
3688   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3689 
3690   // Record whether this pause is an initial mark. When the current
3691   // thread has completed its logging output and it's safe to signal
3692   // the CM thread, the flag's value in the policy has been reset.
3693   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3694 
3695   // Inner scope for scope based logging, timers, and stats collection
3696   {
3697     EvacuationInfo evacuation_info;
3698 
3699     if (g1_policy()->during_initial_mark_pause()) {
3700       // We are about to start a marking cycle, so we increment the
3701       // full collection counter.
3702       increment_old_marking_cycles_started();
3703       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3704     }
3705 
3706     _gc_tracer_stw->report_yc_type(yc_type());
3707 
3708     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3709 
3710     int active_workers = workers()->active_workers();
3711     double pause_start_sec = os::elapsedTime();
3712     g1_policy()->phase_times()->note_gc_start(active_workers);
3713     log_gc_header();
3714 
3715     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3716     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3717 
3718     // If the secondary_free_list is not empty, append it to the
3719     // free_list. No need to wait for the cleanup operation to finish;
3720     // the region allocation code will check the secondary_free_list
3721     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3722     // set, skip this step so that the region allocation code has to
3723     // get entries from the secondary_free_list.
3724     if (!G1StressConcRegionFreeing) {
3725       append_secondary_free_list_if_not_empty_with_lock();
3726     }
3727 
3728     assert(check_young_list_well_formed(), "young list should be well formed");
3729 
3730     // Don't dynamically change the number of GC threads this early.  A value of
3731     // 0 is used to indicate serial work.  When parallel work is done,
3732     // it will be set.
3733 
3734     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3735       IsGCActiveMark x;
3736 
3737       gc_prologue(false);
3738       increment_total_collections(false /* full gc */);
3739       increment_gc_time_stamp();
3740 
3741       verify_before_gc();
3742 
3743       check_bitmaps("GC Start");
3744 
3745       COMPILER2_PRESENT(DerivedPointerTable::clear());
3746 
3747       // Please see comment in g1CollectedHeap.hpp and
3748       // G1CollectedHeap::ref_processing_init() to see how
3749       // reference processing currently works in G1.
3750 
3751       // Enable discovery in the STW reference processor
3752       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3753                                             true /*verify_no_refs*/);
3754 
3755       {
3756         // We want to temporarily turn off discovery by the
3757         // CM ref processor, if necessary, and turn it back on
3758         // on again later if we do. Using a scoped
3759         // NoRefDiscovery object will do this.
3760         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3761 
3762         // Forget the current alloc region (we might even choose it to be part
3763         // of the collection set!).
3764         _allocator->release_mutator_alloc_region();
3765 
3766         // We should call this after we retire the mutator alloc
3767         // region(s) so that all the ALLOC / RETIRE events are generated
3768         // before the start GC event.
3769         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3770 
3771         // This timing is only used by the ergonomics to handle our pause target.
3772         // It is unclear why this should not include the full pause. We will
3773         // investigate this in CR 7178365.
3774         //
3775         // Preserving the old comment here if that helps the investigation:
3776         //
3777         // The elapsed time induced by the start time below deliberately elides
3778         // the possible verification above.
3779         double sample_start_time_sec = os::elapsedTime();
3780 
3781 #if YOUNG_LIST_VERBOSE
3782         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3783         _young_list->print();
3784         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3785 #endif // YOUNG_LIST_VERBOSE
3786 
3787         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3788 
3789         double scan_wait_start = os::elapsedTime();
3790         // We have to wait until the CM threads finish scanning the
3791         // root regions as it's the only way to ensure that all the
3792         // objects on them have been correctly scanned before we start
3793         // moving them during the GC.
3794         bool waited = _cm->root_regions()->wait_until_scan_finished();
3795         double wait_time_ms = 0.0;
3796         if (waited) {
3797           double scan_wait_end = os::elapsedTime();
3798           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3799         }
3800         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3801 
3802 #if YOUNG_LIST_VERBOSE
3803         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3804         _young_list->print();
3805 #endif // YOUNG_LIST_VERBOSE
3806 
3807         if (g1_policy()->during_initial_mark_pause()) {
3808           concurrent_mark()->checkpointRootsInitialPre();
3809         }
3810 
3811 #if YOUNG_LIST_VERBOSE
3812         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3813         _young_list->print();
3814         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3815 #endif // YOUNG_LIST_VERBOSE
3816 
3817         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3818 
3819         register_humongous_regions_with_in_cset_fast_test();
3820 
3821         _cm->note_start_of_gc();
3822         // We should not verify the per-thread SATB buffers given that
3823         // we have not filtered them yet (we'll do so during the
3824         // GC). We also call this after finalize_cset() to
3825         // ensure that the CSet has been finalized.
3826         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3827                                  true  /* verify_enqueued_buffers */,
3828                                  false /* verify_thread_buffers */,
3829                                  true  /* verify_fingers */);
3830 
3831         if (_hr_printer.is_active()) {
3832           HeapRegion* hr = g1_policy()->collection_set();
3833           while (hr != NULL) {
3834             _hr_printer.cset(hr);
3835             hr = hr->next_in_collection_set();
3836           }
3837         }
3838 
3839 #ifdef ASSERT
3840         VerifyCSetClosure cl;
3841         collection_set_iterate(&cl);
3842 #endif // ASSERT
3843 
3844         setup_surviving_young_words();
3845 
3846         // Initialize the GC alloc regions.
3847         _allocator->init_gc_alloc_regions(evacuation_info);
3848 
3849         // Actually do the work...
3850         evacuate_collection_set(evacuation_info);
3851 
3852         // We do this to mainly verify the per-thread SATB buffers
3853         // (which have been filtered by now) since we didn't verify
3854         // them earlier. No point in re-checking the stacks / enqueued
3855         // buffers given that the CSet has not changed since last time
3856         // we checked.
3857         _cm->verify_no_cset_oops(false /* verify_stacks */,
3858                                  false /* verify_enqueued_buffers */,
3859                                  true  /* verify_thread_buffers */,
3860                                  true  /* verify_fingers */);
3861 
3862         free_collection_set(g1_policy()->collection_set(), evacuation_info);
3863 
3864         eagerly_reclaim_humongous_regions();
3865 
3866         g1_policy()->clear_collection_set();
3867 
3868         cleanup_surviving_young_words();
3869 
3870         // Start a new incremental collection set for the next pause.
3871         g1_policy()->start_incremental_cset_building();
3872 
3873         clear_cset_fast_test();
3874 
3875         _young_list->reset_sampled_info();
3876 
3877         // Don't check the whole heap at this point as the
3878         // GC alloc regions from this pause have been tagged
3879         // as survivors and moved on to the survivor list.
3880         // Survivor regions will fail the !is_young() check.
3881         assert(check_young_list_empty(false /* check_heap */),
3882           "young list should be empty");
3883 
3884 #if YOUNG_LIST_VERBOSE
3885         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3886         _young_list->print();
3887 #endif // YOUNG_LIST_VERBOSE
3888 
3889         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3890                                              _young_list->first_survivor_region(),
3891                                              _young_list->last_survivor_region());
3892 
3893         _young_list->reset_auxilary_lists();
3894 
3895         if (evacuation_failed()) {
3896           _allocator->set_used(recalculate_used());
3897           uint n_queues = MAX2((int)ParallelGCThreads, 1);
3898           for (uint i = 0; i < n_queues; i++) {
3899             if (_evacuation_failed_info_array[i].has_failed()) {
3900               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3901             }
3902           }
3903         } else {
3904           // The "used" of the the collection set have already been subtracted
3905           // when they were freed.  Add in the bytes evacuated.
3906           _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3907         }
3908 
3909         if (g1_policy()->during_initial_mark_pause()) {
3910           // We have to do this before we notify the CM threads that
3911           // they can start working to make sure that all the
3912           // appropriate initialization is done on the CM object.
3913           concurrent_mark()->checkpointRootsInitialPost();
3914           set_marking_started();
3915           // Note that we don't actually trigger the CM thread at
3916           // this point. We do that later when we're sure that
3917           // the current thread has completed its logging output.
3918         }
3919 
3920         allocate_dummy_regions();
3921 
3922 #if YOUNG_LIST_VERBOSE
3923         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3924         _young_list->print();
3925         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3926 #endif // YOUNG_LIST_VERBOSE
3927 
3928         _allocator->init_mutator_alloc_region();
3929 
3930         {
3931           size_t expand_bytes = g1_policy()->expansion_amount();
3932           if (expand_bytes > 0) {
3933             size_t bytes_before = capacity();
3934             // No need for an ergo verbose message here,
3935             // expansion_amount() does this when it returns a value > 0.
3936             if (!expand(expand_bytes)) {
3937               // We failed to expand the heap. Cannot do anything about it.
3938             }
3939           }
3940         }
3941 
3942         // We redo the verification but now wrt to the new CSet which
3943         // has just got initialized after the previous CSet was freed.
3944         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3945                                  true  /* verify_enqueued_buffers */,
3946                                  true  /* verify_thread_buffers */,
3947                                  true  /* verify_fingers */);
3948         _cm->note_end_of_gc();
3949 
3950         // This timing is only used by the ergonomics to handle our pause target.
3951         // It is unclear why this should not include the full pause. We will
3952         // investigate this in CR 7178365.
3953         double sample_end_time_sec = os::elapsedTime();
3954         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3955         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3956 
3957         MemoryService::track_memory_usage();
3958 
3959         // In prepare_for_verify() below we'll need to scan the deferred
3960         // update buffers to bring the RSets up-to-date if
3961         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3962         // the update buffers we'll probably need to scan cards on the
3963         // regions we just allocated to (i.e., the GC alloc
3964         // regions). However, during the last GC we called
3965         // set_saved_mark() on all the GC alloc regions, so card
3966         // scanning might skip the [saved_mark_word()...top()] area of
3967         // those regions (i.e., the area we allocated objects into
3968         // during the last GC). But it shouldn't. Given that
3969         // saved_mark_word() is conditional on whether the GC time stamp
3970         // on the region is current or not, by incrementing the GC time
3971         // stamp here we invalidate all the GC time stamps on all the
3972         // regions and saved_mark_word() will simply return top() for
3973         // all the regions. This is a nicer way of ensuring this rather
3974         // than iterating over the regions and fixing them. In fact, the
3975         // GC time stamp increment here also ensures that
3976         // saved_mark_word() will return top() between pauses, i.e.,
3977         // during concurrent refinement. So we don't need the
3978         // is_gc_active() check to decided which top to use when
3979         // scanning cards (see CR 7039627).
3980         increment_gc_time_stamp();
3981 
3982         verify_after_gc();
3983         check_bitmaps("GC End");
3984 
3985         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3986         ref_processor_stw()->verify_no_references_recorded();
3987 
3988         // CM reference discovery will be re-enabled if necessary.
3989       }
3990 
3991       // We should do this after we potentially expand the heap so
3992       // that all the COMMIT events are generated before the end GC
3993       // event, and after we retire the GC alloc regions so that all
3994       // RETIRE events are generated before the end GC event.
3995       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3996 
3997 #ifdef TRACESPINNING
3998       ParallelTaskTerminator::print_termination_counts();
3999 #endif
4000 
4001       gc_epilogue(false);
4002     }
4003 
4004     // Print the remainder of the GC log output.
4005     log_gc_footer(os::elapsedTime() - pause_start_sec);
4006 
4007     // It is not yet to safe to tell the concurrent mark to
4008     // start as we have some optional output below. We don't want the
4009     // output from the concurrent mark thread interfering with this
4010     // logging output either.
4011 
4012     _hrm.verify_optional();
4013     verify_region_sets_optional();
4014 
4015     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4016     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4017 
4018     print_heap_after_gc();
4019     trace_heap_after_gc(_gc_tracer_stw);
4020 
4021     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4022     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4023     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4024     // before any GC notifications are raised.
4025     g1mm()->update_sizes();
4026 
4027     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4028     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4029     _gc_timer_stw->register_gc_end();
4030     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4031   }
4032   // It should now be safe to tell the concurrent mark thread to start
4033   // without its logging output interfering with the logging output
4034   // that came from the pause.
4035 
4036   if (should_start_conc_mark) {
4037     // CAUTION: after the doConcurrentMark() call below,
4038     // the concurrent marking thread(s) could be running
4039     // concurrently with us. Make sure that anything after
4040     // this point does not assume that we are the only GC thread
4041     // running. Note: of course, the actual marking work will
4042     // not start until the safepoint itself is released in
4043     // SuspendibleThreadSet::desynchronize().
4044     doConcurrentMark();
4045   }
4046 
4047   return true;
4048 }
4049 
4050 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4051 {
4052   size_t gclab_word_size;
4053   switch (purpose) {
4054     case GCAllocForSurvived:
4055       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4056       break;
4057     case GCAllocForTenured:
4058       gclab_word_size = _old_plab_stats.desired_plab_sz();
4059       break;
4060     default:
4061       assert(false, "unknown GCAllocPurpose");
4062       gclab_word_size = _old_plab_stats.desired_plab_sz();
4063       break;
4064   }
4065 
4066   // Prevent humongous PLAB sizes for two reasons:
4067   // * PLABs are allocated using a similar paths as oops, but should
4068   //   never be in a humongous region
4069   // * Allowing humongous PLABs needlessly churns the region free lists
4070   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4071 }
4072 
4073 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4074   _drain_in_progress = false;
4075   set_evac_failure_closure(cl);
4076   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4077 }
4078 
4079 void G1CollectedHeap::finalize_for_evac_failure() {
4080   assert(_evac_failure_scan_stack != NULL &&
4081          _evac_failure_scan_stack->length() == 0,
4082          "Postcondition");
4083   assert(!_drain_in_progress, "Postcondition");
4084   delete _evac_failure_scan_stack;
4085   _evac_failure_scan_stack = NULL;
4086 }
4087 
4088 void G1CollectedHeap::remove_self_forwarding_pointers() {
4089   double remove_self_forwards_start = os::elapsedTime();
4090 
4091   set_par_threads();
4092   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4093   workers()->run_task(&rsfp_task);
4094   set_par_threads(0);
4095 
4096   // Now restore saved marks, if any.
4097   assert(_objs_with_preserved_marks.size() ==
4098             _preserved_marks_of_objs.size(), "Both or none.");
4099   while (!_objs_with_preserved_marks.is_empty()) {
4100     oop obj = _objs_with_preserved_marks.pop();
4101     markOop m = _preserved_marks_of_objs.pop();
4102     obj->set_mark(m);
4103   }
4104   _objs_with_preserved_marks.clear(true);
4105   _preserved_marks_of_objs.clear(true);
4106 
4107   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4108 }
4109 
4110 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4111   _evac_failure_scan_stack->push(obj);
4112 }
4113 
4114 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4115   assert(_evac_failure_scan_stack != NULL, "precondition");
4116 
4117   while (_evac_failure_scan_stack->length() > 0) {
4118      oop obj = _evac_failure_scan_stack->pop();
4119      _evac_failure_closure->set_region(heap_region_containing(obj));
4120      obj->oop_iterate_backwards(_evac_failure_closure);
4121   }
4122 }
4123 
4124 oop
4125 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4126                                                oop old) {
4127   assert(obj_in_cs(old),
4128          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4129                  (HeapWord*) old));
4130   markOop m = old->mark();
4131   oop forward_ptr = old->forward_to_atomic(old);
4132   if (forward_ptr == NULL) {
4133     // Forward-to-self succeeded.
4134     assert(_par_scan_state != NULL, "par scan state");
4135     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4136     uint queue_num = _par_scan_state->queue_num();
4137 
4138     _evacuation_failed = true;
4139     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4140     if (_evac_failure_closure != cl) {
4141       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4142       assert(!_drain_in_progress,
4143              "Should only be true while someone holds the lock.");
4144       // Set the global evac-failure closure to the current thread's.
4145       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4146       set_evac_failure_closure(cl);
4147       // Now do the common part.
4148       handle_evacuation_failure_common(old, m);
4149       // Reset to NULL.
4150       set_evac_failure_closure(NULL);
4151     } else {
4152       // The lock is already held, and this is recursive.
4153       assert(_drain_in_progress, "This should only be the recursive case.");
4154       handle_evacuation_failure_common(old, m);
4155     }
4156     return old;
4157   } else {
4158     // Forward-to-self failed. Either someone else managed to allocate
4159     // space for this object (old != forward_ptr) or they beat us in
4160     // self-forwarding it (old == forward_ptr).
4161     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4162            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4163                    "should not be in the CSet",
4164                    (HeapWord*) old, (HeapWord*) forward_ptr));
4165     return forward_ptr;
4166   }
4167 }
4168 
4169 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4170   preserve_mark_if_necessary(old, m);
4171 
4172   HeapRegion* r = heap_region_containing(old);
4173   if (!r->evacuation_failed()) {
4174     r->set_evacuation_failed(true);
4175     _hr_printer.evac_failure(r);
4176   }
4177 
4178   push_on_evac_failure_scan_stack(old);
4179 
4180   if (!_drain_in_progress) {
4181     // prevent recursion in copy_to_survivor_space()
4182     _drain_in_progress = true;
4183     drain_evac_failure_scan_stack();
4184     _drain_in_progress = false;
4185   }
4186 }
4187 
4188 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4189   assert(evacuation_failed(), "Oversaving!");
4190   // We want to call the "for_promotion_failure" version only in the
4191   // case of a promotion failure.
4192   if (m->must_be_preserved_for_promotion_failure(obj)) {
4193     _objs_with_preserved_marks.push(obj);
4194     _preserved_marks_of_objs.push(m);
4195   }
4196 }
4197 
4198 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4199                                                   size_t word_size,
4200                                                   AllocationContext_t context) {
4201   if (purpose == GCAllocForSurvived) {
4202     HeapWord* result = survivor_attempt_allocation(word_size, context);
4203     if (result != NULL) {
4204       return result;
4205     } else {
4206       // Let's try to allocate in the old gen in case we can fit the
4207       // object there.
4208       return old_attempt_allocation(word_size, context);
4209     }
4210   } else {
4211     assert(purpose ==  GCAllocForTenured, "sanity");
4212     HeapWord* result = old_attempt_allocation(word_size, context);
4213     if (result != NULL) {
4214       return result;
4215     } else {
4216       // Let's try to allocate in the survivors in case we can fit the
4217       // object there.
4218       return survivor_attempt_allocation(word_size, context);
4219     }
4220   }
4221 
4222   ShouldNotReachHere();
4223   // Trying to keep some compilers happy.
4224   return NULL;
4225 }
4226 
4227 void G1ParCopyHelper::mark_object(oop obj) {
4228   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4229 
4230   // We know that the object is not moving so it's safe to read its size.
4231   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4232 }
4233 
4234 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4235   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4236   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4237   assert(from_obj != to_obj, "should not be self-forwarded");
4238 
4239   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4240   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4241 
4242   // The object might be in the process of being copied by another
4243   // worker so we cannot trust that its to-space image is
4244   // well-formed. So we have to read its size from its from-space
4245   // image which we know should not be changing.
4246   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4247 }
4248 
4249 template <class T>
4250 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4251   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4252     _scanned_klass->record_modified_oops();
4253   }
4254 }
4255 
4256 template <G1Barrier barrier, G1Mark do_mark_object>
4257 template <class T>
4258 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4259   T heap_oop = oopDesc::load_heap_oop(p);
4260 
4261   if (oopDesc::is_null(heap_oop)) {
4262     return;
4263   }
4264 
4265   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4266 
4267   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4268 
4269   G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4270 
4271   if (state == G1CollectedHeap::InCSet) {
4272     oop forwardee;
4273     if (obj->is_forwarded()) {
4274       forwardee = obj->forwardee();
4275     } else {
4276       forwardee = _par_scan_state->copy_to_survivor_space(obj);
4277     }
4278     assert(forwardee != NULL, "forwardee should not be NULL");
4279     oopDesc::encode_store_heap_oop(p, forwardee);
4280     if (do_mark_object != G1MarkNone && forwardee != obj) {
4281       // If the object is self-forwarded we don't need to explicitly
4282       // mark it, the evacuation failure protocol will do so.
4283       mark_forwarded_object(obj, forwardee);
4284     }
4285 
4286     if (barrier == G1BarrierKlass) {
4287       do_klass_barrier(p, forwardee);
4288     }
4289   } else {
4290     if (state == G1CollectedHeap::IsHumongous) {
4291       _g1->set_humongous_is_live(obj);
4292     }
4293     // The object is not in collection set. If we're a root scanning
4294     // closure during an initial mark pause then attempt to mark the object.
4295     if (do_mark_object == G1MarkFromRoot) {
4296       mark_object(obj);
4297     }
4298   }
4299 
4300   if (barrier == G1BarrierEvac) {
4301     _par_scan_state->update_rs(_from, p, _worker_id);
4302   }
4303 }
4304 
4305 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4306 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4307 
4308 class G1ParEvacuateFollowersClosure : public VoidClosure {
4309 protected:
4310   G1CollectedHeap*              _g1h;
4311   G1ParScanThreadState*         _par_scan_state;
4312   RefToScanQueueSet*            _queues;
4313   ParallelTaskTerminator*       _terminator;
4314 
4315   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4316   RefToScanQueueSet*      queues()         { return _queues; }
4317   ParallelTaskTerminator* terminator()     { return _terminator; }
4318 
4319 public:
4320   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4321                                 G1ParScanThreadState* par_scan_state,
4322                                 RefToScanQueueSet* queues,
4323                                 ParallelTaskTerminator* terminator)
4324     : _g1h(g1h), _par_scan_state(par_scan_state),
4325       _queues(queues), _terminator(terminator) {}
4326 
4327   void do_void();
4328 
4329 private:
4330   inline bool offer_termination();
4331 };
4332 
4333 bool G1ParEvacuateFollowersClosure::offer_termination() {
4334   G1ParScanThreadState* const pss = par_scan_state();
4335   pss->start_term_time();
4336   const bool res = terminator()->offer_termination();
4337   pss->end_term_time();
4338   return res;
4339 }
4340 
4341 void G1ParEvacuateFollowersClosure::do_void() {
4342   G1ParScanThreadState* const pss = par_scan_state();
4343   pss->trim_queue();
4344   do {
4345     pss->steal_and_trim_queue(queues());
4346   } while (!offer_termination());
4347 }
4348 
4349 class G1KlassScanClosure : public KlassClosure {
4350  G1ParCopyHelper* _closure;
4351  bool             _process_only_dirty;
4352  int              _count;
4353  public:
4354   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4355       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4356   void do_klass(Klass* klass) {
4357     // If the klass has not been dirtied we know that there's
4358     // no references into  the young gen and we can skip it.
4359    if (!_process_only_dirty || klass->has_modified_oops()) {
4360       // Clean the klass since we're going to scavenge all the metadata.
4361       klass->clear_modified_oops();
4362 
4363       // Tell the closure that this klass is the Klass to scavenge
4364       // and is the one to dirty if oops are left pointing into the young gen.
4365       _closure->set_scanned_klass(klass);
4366 
4367       klass->oops_do(_closure);
4368 
4369       _closure->set_scanned_klass(NULL);
4370     }
4371     _count++;
4372   }
4373 };
4374 
4375 class G1CodeBlobClosure : public CodeBlobClosure {
4376   class HeapRegionGatheringOopClosure : public OopClosure {
4377     G1CollectedHeap* _g1h;
4378     OopClosure* _work;
4379     nmethod* _nm;
4380 
4381     template <typename T>
4382     void do_oop_work(T* p) {
4383       _work->do_oop(p);
4384       T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4385       if (!oopDesc::is_null(oop_or_narrowoop)) {
4386         oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4387         HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4388         assert(!_g1h->obj_in_cs(o) || hr->rem_set()->strong_code_roots_list_contains(_nm), "if o still in CS then evacuation failed and nm must already be in the remset");
4389         hr->add_strong_code_root(_nm);
4390       }
4391     }
4392 
4393   public:
4394     HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4395 
4396     void do_oop(oop* o) {
4397       do_oop_work(o);
4398     }
4399 
4400     void do_oop(narrowOop* o) {
4401       do_oop_work(o);
4402     }
4403 
4404     void set_nm(nmethod* nm) {
4405       _nm = nm;
4406     }
4407   };
4408 
4409   HeapRegionGatheringOopClosure _oc;
4410 public:
4411   G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4412 
4413   void do_code_blob(CodeBlob* cb) {
4414     nmethod* nm = cb->as_nmethod_or_null();
4415     if (nm != NULL) {
4416       if (!nm->test_set_oops_do_mark()) {
4417         _oc.set_nm(nm);
4418         nm->oops_do(&_oc);
4419         nm->fix_oop_relocations();
4420       }
4421     }
4422   }
4423 };
4424 
4425 class G1ParTask : public AbstractGangTask {
4426 protected:
4427   G1CollectedHeap*       _g1h;
4428   RefToScanQueueSet      *_queues;
4429   ParallelTaskTerminator _terminator;
4430   uint _n_workers;
4431 
4432   Mutex _stats_lock;
4433   Mutex* stats_lock() { return &_stats_lock; }
4434 
4435 public:
4436   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4437     : AbstractGangTask("G1 collection"),
4438       _g1h(g1h),
4439       _queues(task_queues),
4440       _terminator(0, _queues),
4441       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4442   {}
4443 
4444   RefToScanQueueSet* queues() { return _queues; }
4445 
4446   RefToScanQueue *work_queue(int i) {
4447     return queues()->queue(i);
4448   }
4449 
4450   ParallelTaskTerminator* terminator() { return &_terminator; }
4451 
4452   virtual void set_for_termination(int active_workers) {
4453     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4454     // in the young space (_par_seq_tasks) in the G1 heap
4455     // for SequentialSubTasksDone.
4456     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4457     // both of which need setting by set_n_termination().
4458     _g1h->SharedHeap::set_n_termination(active_workers);
4459     _g1h->set_n_termination(active_workers);
4460     terminator()->reset_for_reuse(active_workers);
4461     _n_workers = active_workers;
4462   }
4463 
4464   // Helps out with CLD processing.
4465   //
4466   // During InitialMark we need to:
4467   // 1) Scavenge all CLDs for the young GC.
4468   // 2) Mark all objects directly reachable from strong CLDs.
4469   template <G1Mark do_mark_object>
4470   class G1CLDClosure : public CLDClosure {
4471     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4472     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4473     G1KlassScanClosure                                _klass_in_cld_closure;
4474     bool                                              _claim;
4475 
4476    public:
4477     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4478                  bool only_young, bool claim)
4479         : _oop_closure(oop_closure),
4480           _oop_in_klass_closure(oop_closure->g1(),
4481                                 oop_closure->pss(),
4482                                 oop_closure->rp()),
4483           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4484           _claim(claim) {
4485 
4486     }
4487 
4488     void do_cld(ClassLoaderData* cld) {
4489       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4490     }
4491   };
4492 
4493   void work(uint worker_id) {
4494     if (worker_id >= _n_workers) return;  // no work needed this round
4495 
4496     double start_time_ms = os::elapsedTime() * 1000.0;
4497     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4498 
4499     {
4500       ResourceMark rm;
4501       HandleMark   hm;
4502 
4503       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4504 
4505       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4506       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4507 
4508       pss.set_evac_failure_closure(&evac_failure_cl);
4509 
4510       bool only_young = _g1h->g1_policy()->gcs_are_young();
4511 
4512       // Non-IM young GC.
4513       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4514       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4515                                                                                only_young, // Only process dirty klasses.
4516                                                                                false);     // No need to claim CLDs.
4517       // IM young GC.
4518       //    Strong roots closures.
4519       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4520       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4521                                                                                false, // Process all klasses.
4522                                                                                true); // Need to claim CLDs.
4523       //    Weak roots closures.
4524       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4525       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4526                                                                                     false, // Process all klasses.
4527                                                                                     true); // Need to claim CLDs.
4528 
4529       G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4530       G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4531       // IM Weak code roots are handled later.
4532 
4533       OopClosure* strong_root_cl;
4534       OopClosure* weak_root_cl;
4535       CLDClosure* strong_cld_cl;
4536       CLDClosure* weak_cld_cl;
4537       CodeBlobClosure* strong_code_cl;
4538 
4539       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4540         // We also need to mark copied objects.
4541         strong_root_cl = &scan_mark_root_cl;
4542         strong_cld_cl  = &scan_mark_cld_cl;
4543         strong_code_cl = &scan_mark_code_cl;
4544         if (ClassUnloadingWithConcurrentMark) {
4545           weak_root_cl = &scan_mark_weak_root_cl;
4546           weak_cld_cl  = &scan_mark_weak_cld_cl;
4547         } else {
4548           weak_root_cl = &scan_mark_root_cl;
4549           weak_cld_cl  = &scan_mark_cld_cl;
4550         }
4551       } else {
4552         strong_root_cl = &scan_only_root_cl;
4553         weak_root_cl   = &scan_only_root_cl;
4554         strong_cld_cl  = &scan_only_cld_cl;
4555         weak_cld_cl    = &scan_only_cld_cl;
4556         strong_code_cl = &scan_only_code_cl;
4557       }
4558 
4559 
4560       G1ParPushHeapRSClosure  push_heap_rs_cl(_g1h, &pss);
4561 
4562       pss.start_strong_roots();
4563       _g1h->g1_process_roots(strong_root_cl,
4564                              weak_root_cl,
4565                              &push_heap_rs_cl,
4566                              strong_cld_cl,
4567                              weak_cld_cl,
4568                              strong_code_cl,
4569                              worker_id);
4570 
4571       pss.end_strong_roots();
4572 
4573       {
4574         double start = os::elapsedTime();
4575         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4576         evac.do_void();
4577         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4578         double term_ms = pss.term_time()*1000.0;
4579         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4580         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4581       }
4582       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4583       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4584 
4585       if (PrintTerminationStats) {
4586         MutexLocker x(stats_lock());
4587         pss.print_termination_stats(worker_id);
4588       }
4589 
4590       assert(pss.queue_is_empty(), "should be empty");
4591 
4592       // Close the inner scope so that the ResourceMark and HandleMark
4593       // destructors are executed here and are included as part of the
4594       // "GC Worker Time".
4595     }
4596 
4597     double end_time_ms = os::elapsedTime() * 1000.0;
4598     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4599   }
4600 };
4601 
4602 // *** Common G1 Evacuation Stuff
4603 
4604 // This method is run in a GC worker.
4605 
4606 void
4607 G1CollectedHeap::
4608 g1_process_roots(OopClosure* scan_non_heap_roots,
4609                  OopClosure* scan_non_heap_weak_roots,
4610                  OopsInHeapRegionClosure* scan_rs,
4611                  CLDClosure* scan_strong_clds,
4612                  CLDClosure* scan_weak_clds,
4613                  CodeBlobClosure* scan_strong_code,
4614                  uint worker_i) {
4615 
4616   // First scan the shared roots.
4617   double ext_roots_start = os::elapsedTime();
4618   double closure_app_time_sec = 0.0;
4619 
4620   bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4621   bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4622 
4623   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4624   BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4625 
4626   process_roots(false, // no scoping; this is parallel code
4627                 SharedHeap::SO_None,
4628                 &buf_scan_non_heap_roots,
4629                 &buf_scan_non_heap_weak_roots,
4630                 scan_strong_clds,
4631                 // Unloading Initial Marks handle the weak CLDs separately.
4632                 (trace_metadata ? NULL : scan_weak_clds),
4633                 scan_strong_code);
4634 
4635   // Now the CM ref_processor roots.
4636   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4637     // We need to treat the discovered reference lists of the
4638     // concurrent mark ref processor as roots and keep entries
4639     // (which are added by the marking threads) on them live
4640     // until they can be processed at the end of marking.
4641     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4642   }
4643 
4644   if (trace_metadata) {
4645     // Barrier to make sure all workers passed
4646     // the strong CLD and strong nmethods phases.
4647     active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4648 
4649     // Now take the complement of the strong CLDs.
4650     ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4651   }
4652 
4653   // Finish up any enqueued closure apps (attributed as object copy time).
4654   buf_scan_non_heap_roots.done();
4655   buf_scan_non_heap_weak_roots.done();
4656 
4657   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4658       + buf_scan_non_heap_weak_roots.closure_app_seconds();
4659 
4660   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4661 
4662   double ext_root_time_ms =
4663     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4664 
4665   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4666 
4667   // During conc marking we have to filter the per-thread SATB buffers
4668   // to make sure we remove any oops into the CSet (which will show up
4669   // as implicitly live).
4670   double satb_filtering_ms = 0.0;
4671   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4672     if (mark_in_progress()) {
4673       double satb_filter_start = os::elapsedTime();
4674 
4675       JavaThread::satb_mark_queue_set().filter_thread_buffers();
4676 
4677       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4678     }
4679   }
4680   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4681 
4682   // Now scan the complement of the collection set.
4683   G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4684 
4685   g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4686 
4687   _process_strong_tasks->all_tasks_completed();
4688 }
4689 
4690 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4691 private:
4692   BoolObjectClosure* _is_alive;
4693   int _initial_string_table_size;
4694   int _initial_symbol_table_size;
4695 
4696   bool  _process_strings;
4697   int _strings_processed;
4698   int _strings_removed;
4699 
4700   bool  _process_symbols;
4701   int _symbols_processed;
4702   int _symbols_removed;
4703 
4704 public:
4705   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4706     AbstractGangTask("String/Symbol Unlinking"),
4707     _is_alive(is_alive),
4708     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4709     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4710 
4711     _initial_string_table_size = StringTable::the_table()->table_size();
4712     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4713     if (process_strings) {
4714       StringTable::clear_parallel_claimed_index();
4715     }
4716     if (process_symbols) {
4717       SymbolTable::clear_parallel_claimed_index();
4718     }
4719   }
4720 
4721   ~G1StringSymbolTableUnlinkTask() {
4722     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4723               err_msg("claim value %d after unlink less than initial string table size %d",
4724                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4725     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4726               err_msg("claim value %d after unlink less than initial symbol table size %d",
4727                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4728 
4729     if (G1TraceStringSymbolTableScrubbing) {
4730       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4731                              "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4732                              "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4733                              strings_processed(), strings_removed(),
4734                              symbols_processed(), symbols_removed());
4735     }
4736   }
4737 
4738   void work(uint worker_id) {
4739     int strings_processed = 0;
4740     int strings_removed = 0;
4741     int symbols_processed = 0;
4742     int symbols_removed = 0;
4743     if (_process_strings) {
4744       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4745       Atomic::add(strings_processed, &_strings_processed);
4746       Atomic::add(strings_removed, &_strings_removed);
4747     }
4748     if (_process_symbols) {
4749       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4750       Atomic::add(symbols_processed, &_symbols_processed);
4751       Atomic::add(symbols_removed, &_symbols_removed);
4752     }
4753   }
4754 
4755   size_t strings_processed() const { return (size_t)_strings_processed; }
4756   size_t strings_removed()   const { return (size_t)_strings_removed; }
4757 
4758   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4759   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4760 };
4761 
4762 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4763 private:
4764   static Monitor* _lock;
4765 
4766   BoolObjectClosure* const _is_alive;
4767   const bool               _unloading_occurred;
4768   const uint               _num_workers;
4769 
4770   // Variables used to claim nmethods.
4771   nmethod* _first_nmethod;
4772   volatile nmethod* _claimed_nmethod;
4773 
4774   // The list of nmethods that need to be processed by the second pass.
4775   volatile nmethod* _postponed_list;
4776   volatile uint     _num_entered_barrier;
4777 
4778  public:
4779   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4780       _is_alive(is_alive),
4781       _unloading_occurred(unloading_occurred),
4782       _num_workers(num_workers),
4783       _first_nmethod(NULL),
4784       _claimed_nmethod(NULL),
4785       _postponed_list(NULL),
4786       _num_entered_barrier(0)
4787   {
4788     nmethod::increase_unloading_clock();
4789     // Get first alive nmethod
4790     NMethodIterator iter = NMethodIterator();
4791     if(iter.next_alive()) {
4792       _first_nmethod = iter.method();
4793     }
4794     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4795   }
4796 
4797   ~G1CodeCacheUnloadingTask() {
4798     CodeCache::verify_clean_inline_caches();
4799 
4800     CodeCache::set_needs_cache_clean(false);
4801     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4802 
4803     CodeCache::verify_icholder_relocations();
4804   }
4805 
4806  private:
4807   void add_to_postponed_list(nmethod* nm) {
4808       nmethod* old;
4809       do {
4810         old = (nmethod*)_postponed_list;
4811         nm->set_unloading_next(old);
4812       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4813   }
4814 
4815   void clean_nmethod(nmethod* nm) {
4816     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4817 
4818     if (postponed) {
4819       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4820       add_to_postponed_list(nm);
4821     }
4822 
4823     // Mark that this thread has been cleaned/unloaded.
4824     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4825     nm->set_unloading_clock(nmethod::global_unloading_clock());
4826   }
4827 
4828   void clean_nmethod_postponed(nmethod* nm) {
4829     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4830   }
4831 
4832   static const int MaxClaimNmethods = 16;
4833 
4834   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4835     nmethod* first;
4836     NMethodIterator last;
4837 
4838     do {
4839       *num_claimed_nmethods = 0;
4840 
4841       first = (nmethod*)_claimed_nmethod;
4842       last = NMethodIterator(first);
4843 
4844       if (first != NULL) {
4845 
4846         for (int i = 0; i < MaxClaimNmethods; i++) {
4847           if (!last.next_alive()) {
4848             break;
4849           }
4850           claimed_nmethods[i] = last.method();
4851           (*num_claimed_nmethods)++;
4852         }
4853       }
4854 
4855     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4856   }
4857 
4858   nmethod* claim_postponed_nmethod() {
4859     nmethod* claim;
4860     nmethod* next;
4861 
4862     do {
4863       claim = (nmethod*)_postponed_list;
4864       if (claim == NULL) {
4865         return NULL;
4866       }
4867 
4868       next = claim->unloading_next();
4869 
4870     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4871 
4872     return claim;
4873   }
4874 
4875  public:
4876   // Mark that we're done with the first pass of nmethod cleaning.
4877   void barrier_mark(uint worker_id) {
4878     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4879     _num_entered_barrier++;
4880     if (_num_entered_barrier == _num_workers) {
4881       ml.notify_all();
4882     }
4883   }
4884 
4885   // See if we have to wait for the other workers to
4886   // finish their first-pass nmethod cleaning work.
4887   void barrier_wait(uint worker_id) {
4888     if (_num_entered_barrier < _num_workers) {
4889       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4890       while (_num_entered_barrier < _num_workers) {
4891           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4892       }
4893     }
4894   }
4895 
4896   // Cleaning and unloading of nmethods. Some work has to be postponed
4897   // to the second pass, when we know which nmethods survive.
4898   void work_first_pass(uint worker_id) {
4899     // The first nmethods is claimed by the first worker.
4900     if (worker_id == 0 && _first_nmethod != NULL) {
4901       clean_nmethod(_first_nmethod);
4902       _first_nmethod = NULL;
4903     }
4904 
4905     int num_claimed_nmethods;
4906     nmethod* claimed_nmethods[MaxClaimNmethods];
4907 
4908     while (true) {
4909       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4910 
4911       if (num_claimed_nmethods == 0) {
4912         break;
4913       }
4914 
4915       for (int i = 0; i < num_claimed_nmethods; i++) {
4916         clean_nmethod(claimed_nmethods[i]);
4917       }
4918     }
4919 
4920     // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4921     // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4922     MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4923   }
4924 
4925   void work_second_pass(uint worker_id) {
4926     nmethod* nm;
4927     // Take care of postponed nmethods.
4928     while ((nm = claim_postponed_nmethod()) != NULL) {
4929       clean_nmethod_postponed(nm);
4930     }
4931   }
4932 };
4933 
4934 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
4935 
4936 class G1KlassCleaningTask : public StackObj {
4937   BoolObjectClosure*                      _is_alive;
4938   volatile jint                           _clean_klass_tree_claimed;
4939   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4940 
4941  public:
4942   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4943       _is_alive(is_alive),
4944       _clean_klass_tree_claimed(0),
4945       _klass_iterator() {
4946   }
4947 
4948  private:
4949   bool claim_clean_klass_tree_task() {
4950     if (_clean_klass_tree_claimed) {
4951       return false;
4952     }
4953 
4954     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4955   }
4956 
4957   InstanceKlass* claim_next_klass() {
4958     Klass* klass;
4959     do {
4960       klass =_klass_iterator.next_klass();
4961     } while (klass != NULL && !klass->oop_is_instance());
4962 
4963     return (InstanceKlass*)klass;
4964   }
4965 
4966 public:
4967 
4968   void clean_klass(InstanceKlass* ik) {
4969     ik->clean_implementors_list(_is_alive);
4970     ik->clean_method_data(_is_alive);
4971 
4972     // G1 specific cleanup work that has
4973     // been moved here to be done in parallel.
4974     ik->clean_dependent_nmethods();
4975     if (JvmtiExport::has_redefined_a_class()) {
4976       InstanceKlass::purge_previous_versions(ik);
4977     }
4978   }
4979 
4980   void work() {
4981     ResourceMark rm;
4982 
4983     // One worker will clean the subklass/sibling klass tree.
4984     if (claim_clean_klass_tree_task()) {
4985       Klass::clean_subklass_tree(_is_alive);
4986     }
4987 
4988     // All workers will help cleaning the classes,
4989     InstanceKlass* klass;
4990     while ((klass = claim_next_klass()) != NULL) {
4991       clean_klass(klass);
4992     }
4993   }
4994 };
4995 
4996 // To minimize the remark pause times, the tasks below are done in parallel.
4997 class G1ParallelCleaningTask : public AbstractGangTask {
4998 private:
4999   G1StringSymbolTableUnlinkTask _string_symbol_task;
5000   G1CodeCacheUnloadingTask      _code_cache_task;
5001   G1KlassCleaningTask           _klass_cleaning_task;
5002 
5003 public:
5004   // The constructor is run in the VMThread.
5005   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5006       AbstractGangTask("Parallel Cleaning"),
5007       _string_symbol_task(is_alive, process_strings, process_symbols),
5008       _code_cache_task(num_workers, is_alive, unloading_occurred),
5009       _klass_cleaning_task(is_alive) {
5010   }
5011 
5012   void pre_work_verification() {
5013     assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5014   }
5015 
5016   void post_work_verification() {
5017     assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5018   }
5019 
5020   // The parallel work done by all worker threads.
5021   void work(uint worker_id) {
5022     pre_work_verification();
5023 
5024     // Do first pass of code cache cleaning.
5025     _code_cache_task.work_first_pass(worker_id);
5026 
5027     // Let the threads mark that the first pass is done.
5028     _code_cache_task.barrier_mark(worker_id);
5029 
5030     // Clean the Strings and Symbols.
5031     _string_symbol_task.work(worker_id);
5032 
5033     // Wait for all workers to finish the first code cache cleaning pass.
5034     _code_cache_task.barrier_wait(worker_id);
5035 
5036     // Do the second code cache cleaning work, which realize on
5037     // the liveness information gathered during the first pass.
5038     _code_cache_task.work_second_pass(worker_id);
5039 
5040     // Clean all klasses that were not unloaded.
5041     _klass_cleaning_task.work();
5042 
5043     post_work_verification();
5044   }
5045 };
5046 
5047 
5048 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5049                                         bool process_strings,
5050                                         bool process_symbols,
5051                                         bool class_unloading_occurred) {
5052   uint n_workers = workers()->active_workers();
5053 
5054   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5055                                         n_workers, class_unloading_occurred);
5056   set_par_threads(n_workers);
5057   workers()->run_task(&g1_unlink_task);
5058   set_par_threads(0);
5059 }
5060 
5061 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5062                                                      bool process_strings, bool process_symbols) {
5063   {
5064     uint n_workers = _g1h->workers()->active_workers();
5065     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5066     set_par_threads(n_workers);
5067     workers()->run_task(&g1_unlink_task);
5068     set_par_threads(0);
5069   }
5070 
5071   if (G1StringDedup::is_enabled()) {
5072     G1StringDedup::unlink(is_alive);
5073   }
5074 }
5075 
5076 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5077  private:
5078   DirtyCardQueueSet* _queue;
5079  public:
5080   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5081 
5082   virtual void work(uint worker_id) {
5083     double start_time = os::elapsedTime();
5084 
5085     RedirtyLoggedCardTableEntryClosure cl;
5086     _queue->par_apply_closure_to_all_completed_buffers(&cl);
5087 
5088     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5089     timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5090     timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5091   }
5092 };
5093 
5094 void G1CollectedHeap::redirty_logged_cards() {
5095   double redirty_logged_cards_start = os::elapsedTime();
5096 
5097   uint n_workers = _g1h->workers()->active_workers();
5098 
5099   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5100   dirty_card_queue_set().reset_for_par_iteration();
5101   set_par_threads(n_workers);
5102   workers()->run_task(&redirty_task);
5103   set_par_threads(0);
5104 
5105   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5106   dcq.merge_bufferlists(&dirty_card_queue_set());
5107   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5108 
5109   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5110 }
5111 
5112 // Weak Reference Processing support
5113 
5114 // An always "is_alive" closure that is used to preserve referents.
5115 // If the object is non-null then it's alive.  Used in the preservation
5116 // of referent objects that are pointed to by reference objects
5117 // discovered by the CM ref processor.
5118 class G1AlwaysAliveClosure: public BoolObjectClosure {
5119   G1CollectedHeap* _g1;
5120 public:
5121   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5122   bool do_object_b(oop p) {
5123     if (p != NULL) {
5124       return true;
5125     }
5126     return false;
5127   }
5128 };
5129 
5130 bool G1STWIsAliveClosure::do_object_b(oop p) {
5131   // An object is reachable if it is outside the collection set,
5132   // or is inside and copied.
5133   return !_g1->obj_in_cs(p) || p->is_forwarded();
5134 }
5135 
5136 // Non Copying Keep Alive closure
5137 class G1KeepAliveClosure: public OopClosure {
5138   G1CollectedHeap* _g1;
5139 public:
5140   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5141   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5142   void do_oop(oop* p) {
5143     oop obj = *p;
5144     assert(obj != NULL, "the caller should have filtered out NULL values");
5145 
5146     G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5147     if (cset_state == G1CollectedHeap::InNeither) {
5148       return;
5149     }
5150     if (cset_state == G1CollectedHeap::InCSet) {
5151       assert( obj->is_forwarded(), "invariant" );
5152       *p = obj->forwardee();
5153     } else {
5154       assert(!obj->is_forwarded(), "invariant" );
5155       assert(cset_state == G1CollectedHeap::IsHumongous,
5156              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5157       _g1->set_humongous_is_live(obj);
5158     }
5159   }
5160 };
5161 
5162 // Copying Keep Alive closure - can be called from both
5163 // serial and parallel code as long as different worker
5164 // threads utilize different G1ParScanThreadState instances
5165 // and different queues.
5166 
5167 class G1CopyingKeepAliveClosure: public OopClosure {
5168   G1CollectedHeap*         _g1h;
5169   OopClosure*              _copy_non_heap_obj_cl;
5170   G1ParScanThreadState*    _par_scan_state;
5171 
5172 public:
5173   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5174                             OopClosure* non_heap_obj_cl,
5175                             G1ParScanThreadState* pss):
5176     _g1h(g1h),
5177     _copy_non_heap_obj_cl(non_heap_obj_cl),
5178     _par_scan_state(pss)
5179   {}
5180 
5181   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5182   virtual void do_oop(      oop* p) { do_oop_work(p); }
5183 
5184   template <class T> void do_oop_work(T* p) {
5185     oop obj = oopDesc::load_decode_heap_oop(p);
5186 
5187     if (_g1h->is_in_cset_or_humongous(obj)) {
5188       // If the referent object has been forwarded (either copied
5189       // to a new location or to itself in the event of an
5190       // evacuation failure) then we need to update the reference
5191       // field and, if both reference and referent are in the G1
5192       // heap, update the RSet for the referent.
5193       //
5194       // If the referent has not been forwarded then we have to keep
5195       // it alive by policy. Therefore we have copy the referent.
5196       //
5197       // If the reference field is in the G1 heap then we can push
5198       // on the PSS queue. When the queue is drained (after each
5199       // phase of reference processing) the object and it's followers
5200       // will be copied, the reference field set to point to the
5201       // new location, and the RSet updated. Otherwise we need to
5202       // use the the non-heap or metadata closures directly to copy
5203       // the referent object and update the pointer, while avoiding
5204       // updating the RSet.
5205 
5206       if (_g1h->is_in_g1_reserved(p)) {
5207         _par_scan_state->push_on_queue(p);
5208       } else {
5209         assert(!Metaspace::contains((const void*)p),
5210                err_msg("Unexpectedly found a pointer from metadata: "
5211                               PTR_FORMAT, p));
5212         _copy_non_heap_obj_cl->do_oop(p);
5213       }
5214     }
5215   }
5216 };
5217 
5218 // Serial drain queue closure. Called as the 'complete_gc'
5219 // closure for each discovered list in some of the
5220 // reference processing phases.
5221 
5222 class G1STWDrainQueueClosure: public VoidClosure {
5223 protected:
5224   G1CollectedHeap* _g1h;
5225   G1ParScanThreadState* _par_scan_state;
5226 
5227   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5228 
5229 public:
5230   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5231     _g1h(g1h),
5232     _par_scan_state(pss)
5233   { }
5234 
5235   void do_void() {
5236     G1ParScanThreadState* const pss = par_scan_state();
5237     pss->trim_queue();
5238   }
5239 };
5240 
5241 // Parallel Reference Processing closures
5242 
5243 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5244 // processing during G1 evacuation pauses.
5245 
5246 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5247 private:
5248   G1CollectedHeap*   _g1h;
5249   RefToScanQueueSet* _queues;
5250   FlexibleWorkGang*  _workers;
5251   int                _active_workers;
5252 
5253 public:
5254   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5255                         FlexibleWorkGang* workers,
5256                         RefToScanQueueSet *task_queues,
5257                         int n_workers) :
5258     _g1h(g1h),
5259     _queues(task_queues),
5260     _workers(workers),
5261     _active_workers(n_workers)
5262   {
5263     assert(n_workers > 0, "shouldn't call this otherwise");
5264   }
5265 
5266   // Executes the given task using concurrent marking worker threads.
5267   virtual void execute(ProcessTask& task);
5268   virtual void execute(EnqueueTask& task);
5269 };
5270 
5271 // Gang task for possibly parallel reference processing
5272 
5273 class G1STWRefProcTaskProxy: public AbstractGangTask {
5274   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5275   ProcessTask&     _proc_task;
5276   G1CollectedHeap* _g1h;
5277   RefToScanQueueSet *_task_queues;
5278   ParallelTaskTerminator* _terminator;
5279 
5280 public:
5281   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5282                      G1CollectedHeap* g1h,
5283                      RefToScanQueueSet *task_queues,
5284                      ParallelTaskTerminator* terminator) :
5285     AbstractGangTask("Process reference objects in parallel"),
5286     _proc_task(proc_task),
5287     _g1h(g1h),
5288     _task_queues(task_queues),
5289     _terminator(terminator)
5290   {}
5291 
5292   virtual void work(uint worker_id) {
5293     // The reference processing task executed by a single worker.
5294     ResourceMark rm;
5295     HandleMark   hm;
5296 
5297     G1STWIsAliveClosure is_alive(_g1h);
5298 
5299     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5300     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5301 
5302     pss.set_evac_failure_closure(&evac_failure_cl);
5303 
5304     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5305 
5306     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5307 
5308     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5309 
5310     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5311       // We also need to mark copied objects.
5312       copy_non_heap_cl = &copy_mark_non_heap_cl;
5313     }
5314 
5315     // Keep alive closure.
5316     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5317 
5318     // Complete GC closure
5319     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5320 
5321     // Call the reference processing task's work routine.
5322     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5323 
5324     // Note we cannot assert that the refs array is empty here as not all
5325     // of the processing tasks (specifically phase2 - pp2_work) execute
5326     // the complete_gc closure (which ordinarily would drain the queue) so
5327     // the queue may not be empty.
5328   }
5329 };
5330 
5331 // Driver routine for parallel reference processing.
5332 // Creates an instance of the ref processing gang
5333 // task and has the worker threads execute it.
5334 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5335   assert(_workers != NULL, "Need parallel worker threads.");
5336 
5337   ParallelTaskTerminator terminator(_active_workers, _queues);
5338   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5339 
5340   _g1h->set_par_threads(_active_workers);
5341   _workers->run_task(&proc_task_proxy);
5342   _g1h->set_par_threads(0);
5343 }
5344 
5345 // Gang task for parallel reference enqueueing.
5346 
5347 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5348   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5349   EnqueueTask& _enq_task;
5350 
5351 public:
5352   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5353     AbstractGangTask("Enqueue reference objects in parallel"),
5354     _enq_task(enq_task)
5355   { }
5356 
5357   virtual void work(uint worker_id) {
5358     _enq_task.work(worker_id);
5359   }
5360 };
5361 
5362 // Driver routine for parallel reference enqueueing.
5363 // Creates an instance of the ref enqueueing gang
5364 // task and has the worker threads execute it.
5365 
5366 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5367   assert(_workers != NULL, "Need parallel worker threads.");
5368 
5369   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5370 
5371   _g1h->set_par_threads(_active_workers);
5372   _workers->run_task(&enq_task_proxy);
5373   _g1h->set_par_threads(0);
5374 }
5375 
5376 // End of weak reference support closures
5377 
5378 // Abstract task used to preserve (i.e. copy) any referent objects
5379 // that are in the collection set and are pointed to by reference
5380 // objects discovered by the CM ref processor.
5381 
5382 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5383 protected:
5384   G1CollectedHeap* _g1h;
5385   RefToScanQueueSet      *_queues;
5386   ParallelTaskTerminator _terminator;
5387   uint _n_workers;
5388 
5389 public:
5390   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5391     AbstractGangTask("ParPreserveCMReferents"),
5392     _g1h(g1h),
5393     _queues(task_queues),
5394     _terminator(workers, _queues),
5395     _n_workers(workers)
5396   { }
5397 
5398   void work(uint worker_id) {
5399     ResourceMark rm;
5400     HandleMark   hm;
5401 
5402     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5403     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5404 
5405     pss.set_evac_failure_closure(&evac_failure_cl);
5406 
5407     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5408 
5409     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5410 
5411     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5412 
5413     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5414 
5415     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5416       // We also need to mark copied objects.
5417       copy_non_heap_cl = &copy_mark_non_heap_cl;
5418     }
5419 
5420     // Is alive closure
5421     G1AlwaysAliveClosure always_alive(_g1h);
5422 
5423     // Copying keep alive closure. Applied to referent objects that need
5424     // to be copied.
5425     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5426 
5427     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5428 
5429     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5430     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5431 
5432     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5433     // So this must be true - but assert just in case someone decides to
5434     // change the worker ids.
5435     assert(0 <= worker_id && worker_id < limit, "sanity");
5436     assert(!rp->discovery_is_atomic(), "check this code");
5437 
5438     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5439     for (uint idx = worker_id; idx < limit; idx += stride) {
5440       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5441 
5442       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5443       while (iter.has_next()) {
5444         // Since discovery is not atomic for the CM ref processor, we
5445         // can see some null referent objects.
5446         iter.load_ptrs(DEBUG_ONLY(true));
5447         oop ref = iter.obj();
5448 
5449         // This will filter nulls.
5450         if (iter.is_referent_alive()) {
5451           iter.make_referent_alive();
5452         }
5453         iter.move_to_next();
5454       }
5455     }
5456 
5457     // Drain the queue - which may cause stealing
5458     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5459     drain_queue.do_void();
5460     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5461     assert(pss.queue_is_empty(), "should be");
5462   }
5463 };
5464 
5465 // Weak Reference processing during an evacuation pause (part 1).
5466 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5467   double ref_proc_start = os::elapsedTime();
5468 
5469   ReferenceProcessor* rp = _ref_processor_stw;
5470   assert(rp->discovery_enabled(), "should have been enabled");
5471 
5472   // Any reference objects, in the collection set, that were 'discovered'
5473   // by the CM ref processor should have already been copied (either by
5474   // applying the external root copy closure to the discovered lists, or
5475   // by following an RSet entry).
5476   //
5477   // But some of the referents, that are in the collection set, that these
5478   // reference objects point to may not have been copied: the STW ref
5479   // processor would have seen that the reference object had already
5480   // been 'discovered' and would have skipped discovering the reference,
5481   // but would not have treated the reference object as a regular oop.
5482   // As a result the copy closure would not have been applied to the
5483   // referent object.
5484   //
5485   // We need to explicitly copy these referent objects - the references
5486   // will be processed at the end of remarking.
5487   //
5488   // We also need to do this copying before we process the reference
5489   // objects discovered by the STW ref processor in case one of these
5490   // referents points to another object which is also referenced by an
5491   // object discovered by the STW ref processor.
5492 
5493   assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5494 
5495   set_par_threads(no_of_gc_workers);
5496   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5497                                                  no_of_gc_workers,
5498                                                  _task_queues);
5499 
5500   workers()->run_task(&keep_cm_referents);
5501 
5502   set_par_threads(0);
5503 
5504   // Closure to test whether a referent is alive.
5505   G1STWIsAliveClosure is_alive(this);
5506 
5507   // Even when parallel reference processing is enabled, the processing
5508   // of JNI refs is serial and performed serially by the current thread
5509   // rather than by a worker. The following PSS will be used for processing
5510   // JNI refs.
5511 
5512   // Use only a single queue for this PSS.
5513   G1ParScanThreadState            pss(this, 0, NULL);
5514 
5515   // We do not embed a reference processor in the copying/scanning
5516   // closures while we're actually processing the discovered
5517   // reference objects.
5518   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5519 
5520   pss.set_evac_failure_closure(&evac_failure_cl);
5521 
5522   assert(pss.queue_is_empty(), "pre-condition");
5523 
5524   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5525 
5526   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5527 
5528   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5529 
5530   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5531     // We also need to mark copied objects.
5532     copy_non_heap_cl = &copy_mark_non_heap_cl;
5533   }
5534 
5535   // Keep alive closure.
5536   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5537 
5538   // Serial Complete GC closure
5539   G1STWDrainQueueClosure drain_queue(this, &pss);
5540 
5541   // Setup the soft refs policy...
5542   rp->setup_policy(false);
5543 
5544   ReferenceProcessorStats stats;
5545   if (!rp->processing_is_mt()) {
5546     // Serial reference processing...
5547     stats = rp->process_discovered_references(&is_alive,
5548                                               &keep_alive,
5549                                               &drain_queue,
5550                                               NULL,
5551                                               _gc_timer_stw,
5552                                               _gc_tracer_stw->gc_id());
5553   } else {
5554     // Parallel reference processing
5555     assert(rp->num_q() == no_of_gc_workers, "sanity");
5556     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5557 
5558     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5559     stats = rp->process_discovered_references(&is_alive,
5560                                               &keep_alive,
5561                                               &drain_queue,
5562                                               &par_task_executor,
5563                                               _gc_timer_stw,
5564                                               _gc_tracer_stw->gc_id());
5565   }
5566 
5567   _gc_tracer_stw->report_gc_reference_stats(stats);
5568 
5569   // We have completed copying any necessary live referent objects.
5570   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5571 
5572   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5573   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5574 }
5575 
5576 // Weak Reference processing during an evacuation pause (part 2).
5577 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5578   double ref_enq_start = os::elapsedTime();
5579 
5580   ReferenceProcessor* rp = _ref_processor_stw;
5581   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5582 
5583   // Now enqueue any remaining on the discovered lists on to
5584   // the pending list.
5585   if (!rp->processing_is_mt()) {
5586     // Serial reference processing...
5587     rp->enqueue_discovered_references();
5588   } else {
5589     // Parallel reference enqueueing
5590 
5591     assert(no_of_gc_workers == workers()->active_workers(),
5592            "Need to reset active workers");
5593     assert(rp->num_q() == no_of_gc_workers, "sanity");
5594     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5595 
5596     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5597     rp->enqueue_discovered_references(&par_task_executor);
5598   }
5599 
5600   rp->verify_no_references_recorded();
5601   assert(!rp->discovery_enabled(), "should have been disabled");
5602 
5603   // FIXME
5604   // CM's reference processing also cleans up the string and symbol tables.
5605   // Should we do that here also? We could, but it is a serial operation
5606   // and could significantly increase the pause time.
5607 
5608   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5609   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5610 }
5611 
5612 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5613   _expand_heap_after_alloc_failure = true;
5614   _evacuation_failed = false;
5615 
5616   // Should G1EvacuationFailureALot be in effect for this GC?
5617   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5618 
5619   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5620 
5621   // Disable the hot card cache.
5622   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5623   hot_card_cache->reset_hot_cache_claimed_index();
5624   hot_card_cache->set_use_cache(false);
5625 
5626   uint n_workers;
5627   n_workers =
5628     AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5629                                    workers()->active_workers(),
5630                                    Threads::number_of_non_daemon_threads());
5631   assert(UseDynamicNumberOfGCThreads ||
5632          n_workers == workers()->total_workers(),
5633          "If not dynamic should be using all the  workers");
5634   workers()->set_active_workers(n_workers);
5635   set_par_threads(n_workers);
5636 
5637   G1ParTask g1_par_task(this, _task_queues);
5638 
5639   init_for_evac_failure(NULL);
5640 
5641   rem_set()->prepare_for_younger_refs_iterate(true);
5642 
5643   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5644   double start_par_time_sec = os::elapsedTime();
5645   double end_par_time_sec;
5646 
5647   {
5648     StrongRootsScope srs(this);
5649     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5650     if (g1_policy()->during_initial_mark_pause()) {
5651       ClassLoaderDataGraph::clear_claimed_marks();
5652     }
5653 
5654      // The individual threads will set their evac-failure closures.
5655      if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5656      // These tasks use ShareHeap::_process_strong_tasks
5657      assert(UseDynamicNumberOfGCThreads ||
5658             workers()->active_workers() == workers()->total_workers(),
5659             "If not dynamic should be using all the  workers");
5660     workers()->run_task(&g1_par_task);
5661     end_par_time_sec = os::elapsedTime();
5662 
5663     // Closing the inner scope will execute the destructor
5664     // for the StrongRootsScope object. We record the current
5665     // elapsed time before closing the scope so that time
5666     // taken for the SRS destructor is NOT included in the
5667     // reported parallel time.
5668   }
5669 
5670   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5671   g1_policy()->phase_times()->record_par_time(par_time_ms);
5672 
5673   double code_root_fixup_time_ms =
5674         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5675   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5676 
5677   set_par_threads(0);
5678 
5679   // Process any discovered reference objects - we have
5680   // to do this _before_ we retire the GC alloc regions
5681   // as we may have to copy some 'reachable' referent
5682   // objects (and their reachable sub-graphs) that were
5683   // not copied during the pause.
5684   process_discovered_references(n_workers);
5685 
5686   if (G1StringDedup::is_enabled()) {
5687     G1STWIsAliveClosure is_alive(this);
5688     G1KeepAliveClosure keep_alive(this);
5689     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5690   }
5691 
5692   _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5693   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5694 
5695   // Reset and re-enable the hot card cache.
5696   // Note the counts for the cards in the regions in the
5697   // collection set are reset when the collection set is freed.
5698   hot_card_cache->reset_hot_cache();
5699   hot_card_cache->set_use_cache(true);
5700 
5701   purge_code_root_memory();
5702 
5703   finalize_for_evac_failure();
5704 
5705   if (evacuation_failed()) {
5706     remove_self_forwarding_pointers();
5707 
5708     // Reset the G1EvacuationFailureALot counters and flags
5709     // Note: the values are reset only when an actual
5710     // evacuation failure occurs.
5711     NOT_PRODUCT(reset_evacuation_should_fail();)
5712   }
5713 
5714   // Enqueue any remaining references remaining on the STW
5715   // reference processor's discovered lists. We need to do
5716   // this after the card table is cleaned (and verified) as
5717   // the act of enqueueing entries on to the pending list
5718   // will log these updates (and dirty their associated
5719   // cards). We need these updates logged to update any
5720   // RSets.
5721   enqueue_discovered_references(n_workers);
5722 
5723   redirty_logged_cards();
5724   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5725 }
5726 
5727 void G1CollectedHeap::free_region(HeapRegion* hr,
5728                                   FreeRegionList* free_list,
5729                                   bool par,
5730                                   bool locked) {
5731   assert(!hr->is_free(), "the region should not be free");
5732   assert(!hr->is_empty(), "the region should not be empty");
5733   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5734   assert(free_list != NULL, "pre-condition");
5735 
5736   if (G1VerifyBitmaps) {
5737     MemRegion mr(hr->bottom(), hr->end());
5738     concurrent_mark()->clearRangePrevBitmap(mr);
5739   }
5740 
5741   // Clear the card counts for this region.
5742   // Note: we only need to do this if the region is not young
5743   // (since we don't refine cards in young regions).
5744   if (!hr->is_young()) {
5745     _cg1r->hot_card_cache()->reset_card_counts(hr);
5746   }
5747   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5748   free_list->add_ordered(hr);
5749 }
5750 
5751 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5752                                      FreeRegionList* free_list,
5753                                      bool par) {
5754   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5755   assert(free_list != NULL, "pre-condition");
5756 
5757   size_t hr_capacity = hr->capacity();
5758   // We need to read this before we make the region non-humongous,
5759   // otherwise the information will be gone.
5760   uint last_index = hr->last_hc_index();
5761   hr->clear_humongous();
5762   free_region(hr, free_list, par);
5763 
5764   uint i = hr->hrm_index() + 1;
5765   while (i < last_index) {
5766     HeapRegion* curr_hr = region_at(i);
5767     assert(curr_hr->is_continues_humongous(), "invariant");
5768     curr_hr->clear_humongous();
5769     free_region(curr_hr, free_list, par);
5770     i += 1;
5771   }
5772 }
5773 
5774 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5775                                        const HeapRegionSetCount& humongous_regions_removed) {
5776   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5777     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5778     _old_set.bulk_remove(old_regions_removed);
5779     _humongous_set.bulk_remove(humongous_regions_removed);
5780   }
5781 
5782 }
5783 
5784 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5785   assert(list != NULL, "list can't be null");
5786   if (!list->is_empty()) {
5787     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5788     _hrm.insert_list_into_free_list(list);
5789   }
5790 }
5791 
5792 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5793   _allocator->decrease_used(bytes);
5794 }
5795 
5796 class G1ParCleanupCTTask : public AbstractGangTask {
5797   G1SATBCardTableModRefBS* _ct_bs;
5798   G1CollectedHeap* _g1h;
5799   HeapRegion* volatile _su_head;
5800 public:
5801   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5802                      G1CollectedHeap* g1h) :
5803     AbstractGangTask("G1 Par Cleanup CT Task"),
5804     _ct_bs(ct_bs), _g1h(g1h) { }
5805 
5806   void work(uint worker_id) {
5807     HeapRegion* r;
5808     while (r = _g1h->pop_dirty_cards_region()) {
5809       clear_cards(r);
5810     }
5811   }
5812 
5813   void clear_cards(HeapRegion* r) {
5814     // Cards of the survivors should have already been dirtied.
5815     if (!r->is_survivor()) {
5816       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5817     }
5818   }
5819 };
5820 
5821 #ifndef PRODUCT
5822 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5823   G1CollectedHeap* _g1h;
5824   G1SATBCardTableModRefBS* _ct_bs;
5825 public:
5826   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5827     : _g1h(g1h), _ct_bs(ct_bs) { }
5828   virtual bool doHeapRegion(HeapRegion* r) {
5829     if (r->is_survivor()) {
5830       _g1h->verify_dirty_region(r);
5831     } else {
5832       _g1h->verify_not_dirty_region(r);
5833     }
5834     return false;
5835   }
5836 };
5837 
5838 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5839   // All of the region should be clean.
5840   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5841   MemRegion mr(hr->bottom(), hr->end());
5842   ct_bs->verify_not_dirty_region(mr);
5843 }
5844 
5845 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5846   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5847   // dirty allocated blocks as they allocate them. The thread that
5848   // retires each region and replaces it with a new one will do a
5849   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5850   // not dirty that area (one less thing to have to do while holding
5851   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5852   // is dirty.
5853   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5854   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5855   if (hr->is_young()) {
5856     ct_bs->verify_g1_young_region(mr);
5857   } else {
5858     ct_bs->verify_dirty_region(mr);
5859   }
5860 }
5861 
5862 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5863   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5864   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5865     verify_dirty_region(hr);
5866   }
5867 }
5868 
5869 void G1CollectedHeap::verify_dirty_young_regions() {
5870   verify_dirty_young_list(_young_list->first_region());
5871 }
5872 
5873 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5874                                                HeapWord* tams, HeapWord* end) {
5875   guarantee(tams <= end,
5876             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5877   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5878   if (result < end) {
5879     gclog_or_tty->cr();
5880     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5881                            bitmap_name, result);
5882     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5883                            bitmap_name, tams, end);
5884     return false;
5885   }
5886   return true;
5887 }
5888 
5889 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5890   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5891   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5892 
5893   HeapWord* bottom = hr->bottom();
5894   HeapWord* ptams  = hr->prev_top_at_mark_start();
5895   HeapWord* ntams  = hr->next_top_at_mark_start();
5896   HeapWord* end    = hr->end();
5897 
5898   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5899 
5900   bool res_n = true;
5901   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5902   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5903   // if we happen to be in that state.
5904   if (mark_in_progress() || !_cmThread->in_progress()) {
5905     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5906   }
5907   if (!res_p || !res_n) {
5908     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5909                            HR_FORMAT_PARAMS(hr));
5910     gclog_or_tty->print_cr("#### Caller: %s", caller);
5911     return false;
5912   }
5913   return true;
5914 }
5915 
5916 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5917   if (!G1VerifyBitmaps) return;
5918 
5919   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5920 }
5921 
5922 class G1VerifyBitmapClosure : public HeapRegionClosure {
5923 private:
5924   const char* _caller;
5925   G1CollectedHeap* _g1h;
5926   bool _failures;
5927 
5928 public:
5929   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5930     _caller(caller), _g1h(g1h), _failures(false) { }
5931 
5932   bool failures() { return _failures; }
5933 
5934   virtual bool doHeapRegion(HeapRegion* hr) {
5935     if (hr->is_continues_humongous()) return false;
5936 
5937     bool result = _g1h->verify_bitmaps(_caller, hr);
5938     if (!result) {
5939       _failures = true;
5940     }
5941     return false;
5942   }
5943 };
5944 
5945 void G1CollectedHeap::check_bitmaps(const char* caller) {
5946   if (!G1VerifyBitmaps) return;
5947 
5948   G1VerifyBitmapClosure cl(caller, this);
5949   heap_region_iterate(&cl);
5950   guarantee(!cl.failures(), "bitmap verification");
5951 }
5952 #endif // PRODUCT
5953 
5954 void G1CollectedHeap::cleanUpCardTable() {
5955   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5956   double start = os::elapsedTime();
5957 
5958   {
5959     // Iterate over the dirty cards region list.
5960     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5961 
5962     set_par_threads();
5963     workers()->run_task(&cleanup_task);
5964     set_par_threads(0);
5965 #ifndef PRODUCT
5966     if (G1VerifyCTCleanup || VerifyAfterGC) {
5967       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5968       heap_region_iterate(&cleanup_verifier);
5969     }
5970 #endif
5971   }
5972 
5973   double elapsed = os::elapsedTime() - start;
5974   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5975 }
5976 
5977 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5978   size_t pre_used = 0;
5979   FreeRegionList local_free_list("Local List for CSet Freeing");
5980 
5981   double young_time_ms     = 0.0;
5982   double non_young_time_ms = 0.0;
5983 
5984   // Since the collection set is a superset of the the young list,
5985   // all we need to do to clear the young list is clear its
5986   // head and length, and unlink any young regions in the code below
5987   _young_list->clear();
5988 
5989   G1CollectorPolicy* policy = g1_policy();
5990 
5991   double start_sec = os::elapsedTime();
5992   bool non_young = true;
5993 
5994   HeapRegion* cur = cs_head;
5995   int age_bound = -1;
5996   size_t rs_lengths = 0;
5997 
5998   while (cur != NULL) {
5999     assert(!is_on_master_free_list(cur), "sanity");
6000     if (non_young) {
6001       if (cur->is_young()) {
6002         double end_sec = os::elapsedTime();
6003         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6004         non_young_time_ms += elapsed_ms;
6005 
6006         start_sec = os::elapsedTime();
6007         non_young = false;
6008       }
6009     } else {
6010       if (!cur->is_young()) {
6011         double end_sec = os::elapsedTime();
6012         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6013         young_time_ms += elapsed_ms;
6014 
6015         start_sec = os::elapsedTime();
6016         non_young = true;
6017       }
6018     }
6019 
6020     rs_lengths += cur->rem_set()->occupied_locked();
6021 
6022     HeapRegion* next = cur->next_in_collection_set();
6023     assert(cur->in_collection_set(), "bad CS");
6024     cur->set_next_in_collection_set(NULL);
6025     cur->set_in_collection_set(false);
6026 
6027     if (cur->is_young()) {
6028       int index = cur->young_index_in_cset();
6029       assert(index != -1, "invariant");
6030       assert((uint) index < policy->young_cset_region_length(), "invariant");
6031       size_t words_survived = _surviving_young_words[index];
6032       cur->record_surv_words_in_group(words_survived);
6033 
6034       // At this point the we have 'popped' cur from the collection set
6035       // (linked via next_in_collection_set()) but it is still in the
6036       // young list (linked via next_young_region()). Clear the
6037       // _next_young_region field.
6038       cur->set_next_young_region(NULL);
6039     } else {
6040       int index = cur->young_index_in_cset();
6041       assert(index == -1, "invariant");
6042     }
6043 
6044     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6045             (!cur->is_young() && cur->young_index_in_cset() == -1),
6046             "invariant" );
6047 
6048     if (!cur->evacuation_failed()) {
6049       MemRegion used_mr = cur->used_region();
6050 
6051       // And the region is empty.
6052       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6053       pre_used += cur->used();
6054       free_region(cur, &local_free_list, false /* par */, true /* locked */);
6055     } else {
6056       cur->uninstall_surv_rate_group();
6057       if (cur->is_young()) {
6058         cur->set_young_index_in_cset(-1);
6059       }
6060       cur->set_evacuation_failed(false);
6061       // The region is now considered to be old.
6062       cur->set_old();
6063       _old_set.add(cur);
6064       evacuation_info.increment_collectionset_used_after(cur->used());
6065     }
6066     cur = next;
6067   }
6068 
6069   evacuation_info.set_regions_freed(local_free_list.length());
6070   policy->record_max_rs_lengths(rs_lengths);
6071   policy->cset_regions_freed();
6072 
6073   double end_sec = os::elapsedTime();
6074   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6075 
6076   if (non_young) {
6077     non_young_time_ms += elapsed_ms;
6078   } else {
6079     young_time_ms += elapsed_ms;
6080   }
6081 
6082   prepend_to_freelist(&local_free_list);
6083   decrement_summary_bytes(pre_used);
6084   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6085   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6086 }
6087 
6088 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6089  private:
6090   FreeRegionList* _free_region_list;
6091   HeapRegionSet* _proxy_set;
6092   HeapRegionSetCount _humongous_regions_removed;
6093   size_t _freed_bytes;
6094  public:
6095 
6096   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6097     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6098   }
6099 
6100   virtual bool doHeapRegion(HeapRegion* r) {
6101     if (!r->is_starts_humongous()) {
6102       return false;
6103     }
6104 
6105     G1CollectedHeap* g1h = G1CollectedHeap::heap();
6106 
6107     oop obj = (oop)r->bottom();
6108     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6109 
6110     // The following checks whether the humongous object is live are sufficient.
6111     // The main additional check (in addition to having a reference from the roots
6112     // or the young gen) is whether the humongous object has a remembered set entry.
6113     //
6114     // A humongous object cannot be live if there is no remembered set for it
6115     // because:
6116     // - there can be no references from within humongous starts regions referencing
6117     // the object because we never allocate other objects into them.
6118     // (I.e. there are no intra-region references that may be missed by the
6119     // remembered set)
6120     // - as soon there is a remembered set entry to the humongous starts region
6121     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6122     // until the end of a concurrent mark.
6123     //
6124     // It is not required to check whether the object has been found dead by marking
6125     // or not, in fact it would prevent reclamation within a concurrent cycle, as
6126     // all objects allocated during that time are considered live.
6127     // SATB marking is even more conservative than the remembered set.
6128     // So if at this point in the collection there is no remembered set entry,
6129     // nobody has a reference to it.
6130     // At the start of collection we flush all refinement logs, and remembered sets
6131     // are completely up-to-date wrt to references to the humongous object.
6132     //
6133     // Other implementation considerations:
6134     // - never consider object arrays: while they are a valid target, they have not
6135     // been observed to be used as temporary objects.
6136     // - they would also pose considerable effort for cleaning up the the remembered
6137     // sets.
6138     // While this cleanup is not strictly necessary to be done (or done instantly),
6139     // given that their occurrence is very low, this saves us this additional
6140     // complexity.
6141     uint region_idx = r->hrm_index();
6142     if (g1h->humongous_is_live(region_idx) ||
6143         g1h->humongous_region_is_always_live(region_idx)) {
6144 
6145       if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6146         gclog_or_tty->print_cr("Live humongous %d region %d size "SIZE_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6147                                r->is_humongous(),
6148                                region_idx,
6149                                obj->size()*HeapWordSize,
6150                                r->rem_set()->occupied(),
6151                                r->rem_set()->strong_code_roots_list_length(),
6152                                next_bitmap->isMarked(r->bottom()),
6153                                g1h->humongous_is_live(region_idx),
6154                                obj->is_objArray()
6155                               );
6156       }
6157 
6158       return false;
6159     }
6160 
6161     guarantee(!obj->is_objArray(),
6162               err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6163                       r->bottom()));
6164 
6165     if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6166       gclog_or_tty->print_cr("Reclaim humongous region %d size "SIZE_FORMAT" start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6167                              r->is_humongous(),
6168                              obj->size()*HeapWordSize,
6169                              r->bottom(),
6170                              region_idx,
6171                              r->region_num(),
6172                              r->rem_set()->occupied(),
6173                              r->rem_set()->strong_code_roots_list_length(),
6174                              next_bitmap->isMarked(r->bottom()),
6175                              g1h->humongous_is_live(region_idx),
6176                              obj->is_objArray()
6177                             );
6178     }
6179     // Need to clear mark bit of the humongous object if already set.
6180     if (next_bitmap->isMarked(r->bottom())) {
6181       next_bitmap->clear(r->bottom());
6182     }
6183     _freed_bytes += r->used();
6184     r->set_containing_set(NULL);
6185     _humongous_regions_removed.increment(1u, r->capacity());
6186     g1h->free_humongous_region(r, _free_region_list, false);
6187 
6188     return false;
6189   }
6190 
6191   HeapRegionSetCount& humongous_free_count() {
6192     return _humongous_regions_removed;
6193   }
6194 
6195   size_t bytes_freed() const {
6196     return _freed_bytes;
6197   }
6198 
6199   size_t humongous_reclaimed() const {
6200     return _humongous_regions_removed.length();
6201   }
6202 };
6203 
6204 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6205   assert_at_safepoint(true);
6206 
6207   if (!G1ReclaimDeadHumongousObjectsAtYoungGC ||
6208       (!_has_humongous_reclaim_candidates && !G1TraceReclaimDeadHumongousObjectsAtYoungGC)) {
6209     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6210     return;
6211   }
6212 
6213   double start_time = os::elapsedTime();
6214 
6215   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6216 
6217   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6218   heap_region_iterate(&cl);
6219 
6220   HeapRegionSetCount empty_set;
6221   remove_from_old_sets(empty_set, cl.humongous_free_count());
6222 
6223   G1HRPrinter* hr_printer = _g1h->hr_printer();
6224   if (hr_printer->is_active()) {
6225     FreeRegionListIterator iter(&local_cleanup_list);
6226     while (iter.more_available()) {
6227       HeapRegion* hr = iter.get_next();
6228       hr_printer->cleanup(hr);
6229     }
6230   }
6231 
6232   prepend_to_freelist(&local_cleanup_list);
6233   decrement_summary_bytes(cl.bytes_freed());
6234 
6235   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6236                                                                     cl.humongous_reclaimed());
6237 }
6238 
6239 // This routine is similar to the above but does not record
6240 // any policy statistics or update free lists; we are abandoning
6241 // the current incremental collection set in preparation of a
6242 // full collection. After the full GC we will start to build up
6243 // the incremental collection set again.
6244 // This is only called when we're doing a full collection
6245 // and is immediately followed by the tearing down of the young list.
6246 
6247 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6248   HeapRegion* cur = cs_head;
6249 
6250   while (cur != NULL) {
6251     HeapRegion* next = cur->next_in_collection_set();
6252     assert(cur->in_collection_set(), "bad CS");
6253     cur->set_next_in_collection_set(NULL);
6254     cur->set_in_collection_set(false);
6255     cur->set_young_index_in_cset(-1);
6256     cur = next;
6257   }
6258 }
6259 
6260 void G1CollectedHeap::set_free_regions_coming() {
6261   if (G1ConcRegionFreeingVerbose) {
6262     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6263                            "setting free regions coming");
6264   }
6265 
6266   assert(!free_regions_coming(), "pre-condition");
6267   _free_regions_coming = true;
6268 }
6269 
6270 void G1CollectedHeap::reset_free_regions_coming() {
6271   assert(free_regions_coming(), "pre-condition");
6272 
6273   {
6274     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6275     _free_regions_coming = false;
6276     SecondaryFreeList_lock->notify_all();
6277   }
6278 
6279   if (G1ConcRegionFreeingVerbose) {
6280     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6281                            "reset free regions coming");
6282   }
6283 }
6284 
6285 void G1CollectedHeap::wait_while_free_regions_coming() {
6286   // Most of the time we won't have to wait, so let's do a quick test
6287   // first before we take the lock.
6288   if (!free_regions_coming()) {
6289     return;
6290   }
6291 
6292   if (G1ConcRegionFreeingVerbose) {
6293     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6294                            "waiting for free regions");
6295   }
6296 
6297   {
6298     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6299     while (free_regions_coming()) {
6300       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6301     }
6302   }
6303 
6304   if (G1ConcRegionFreeingVerbose) {
6305     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6306                            "done waiting for free regions");
6307   }
6308 }
6309 
6310 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6311   assert(heap_lock_held_for_gc(),
6312               "the heap lock should already be held by or for this thread");
6313   _young_list->push_region(hr);
6314 }
6315 
6316 class NoYoungRegionsClosure: public HeapRegionClosure {
6317 private:
6318   bool _success;
6319 public:
6320   NoYoungRegionsClosure() : _success(true) { }
6321   bool doHeapRegion(HeapRegion* r) {
6322     if (r->is_young()) {
6323       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6324                              r->bottom(), r->end());
6325       _success = false;
6326     }
6327     return false;
6328   }
6329   bool success() { return _success; }
6330 };
6331 
6332 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6333   bool ret = _young_list->check_list_empty(check_sample);
6334 
6335   if (check_heap) {
6336     NoYoungRegionsClosure closure;
6337     heap_region_iterate(&closure);
6338     ret = ret && closure.success();
6339   }
6340 
6341   return ret;
6342 }
6343 
6344 class TearDownRegionSetsClosure : public HeapRegionClosure {
6345 private:
6346   HeapRegionSet *_old_set;
6347 
6348 public:
6349   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6350 
6351   bool doHeapRegion(HeapRegion* r) {
6352     if (r->is_old()) {
6353       _old_set->remove(r);
6354     } else {
6355       // We ignore free regions, we'll empty the free list afterwards.
6356       // We ignore young regions, we'll empty the young list afterwards.
6357       // We ignore humongous regions, we're not tearing down the
6358       // humongous regions set.
6359       assert(r->is_free() || r->is_young() || r->is_humongous(),
6360              "it cannot be another type");
6361     }
6362     return false;
6363   }
6364 
6365   ~TearDownRegionSetsClosure() {
6366     assert(_old_set->is_empty(), "post-condition");
6367   }
6368 };
6369 
6370 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6371   assert_at_safepoint(true /* should_be_vm_thread */);
6372 
6373   if (!free_list_only) {
6374     TearDownRegionSetsClosure cl(&_old_set);
6375     heap_region_iterate(&cl);
6376 
6377     // Note that emptying the _young_list is postponed and instead done as
6378     // the first step when rebuilding the regions sets again. The reason for
6379     // this is that during a full GC string deduplication needs to know if
6380     // a collected region was young or old when the full GC was initiated.
6381   }
6382   _hrm.remove_all_free_regions();
6383 }
6384 
6385 class RebuildRegionSetsClosure : public HeapRegionClosure {
6386 private:
6387   bool            _free_list_only;
6388   HeapRegionSet*   _old_set;
6389   HeapRegionManager*   _hrm;
6390   size_t          _total_used;
6391 
6392 public:
6393   RebuildRegionSetsClosure(bool free_list_only,
6394                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6395     _free_list_only(free_list_only),
6396     _old_set(old_set), _hrm(hrm), _total_used(0) {
6397     assert(_hrm->num_free_regions() == 0, "pre-condition");
6398     if (!free_list_only) {
6399       assert(_old_set->is_empty(), "pre-condition");
6400     }
6401   }
6402 
6403   bool doHeapRegion(HeapRegion* r) {
6404     if (r->is_continues_humongous()) {
6405       return false;
6406     }
6407 
6408     if (r->is_empty()) {
6409       // Add free regions to the free list
6410       r->set_free();
6411       r->set_allocation_context(AllocationContext::system());
6412       _hrm->insert_into_free_list(r);
6413     } else if (!_free_list_only) {
6414       assert(!r->is_young(), "we should not come across young regions");
6415 
6416       if (r->is_humongous()) {
6417         // We ignore humongous regions, we left the humongous set unchanged
6418       } else {
6419         // Objects that were compacted would have ended up on regions
6420         // that were previously old or free.
6421         assert(r->is_free() || r->is_old(), "invariant");
6422         // We now consider them old, so register as such.
6423         r->set_old();
6424         _old_set->add(r);
6425       }
6426       _total_used += r->used();
6427     }
6428 
6429     return false;
6430   }
6431 
6432   size_t total_used() {
6433     return _total_used;
6434   }
6435 };
6436 
6437 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6438   assert_at_safepoint(true /* should_be_vm_thread */);
6439 
6440   if (!free_list_only) {
6441     _young_list->empty_list();
6442   }
6443 
6444   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6445   heap_region_iterate(&cl);
6446 
6447   if (!free_list_only) {
6448     _allocator->set_used(cl.total_used());
6449   }
6450   assert(_allocator->used_unlocked() == recalculate_used(),
6451          err_msg("inconsistent _allocator->used_unlocked(), "
6452                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6453                  _allocator->used_unlocked(), recalculate_used()));
6454 }
6455 
6456 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6457   _refine_cte_cl->set_concurrent(concurrent);
6458 }
6459 
6460 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6461   HeapRegion* hr = heap_region_containing(p);
6462   return hr->is_in(p);
6463 }
6464 
6465 // Methods for the mutator alloc region
6466 
6467 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6468                                                       bool force) {
6469   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6470   assert(!force || g1_policy()->can_expand_young_list(),
6471          "if force is true we should be able to expand the young list");
6472   bool young_list_full = g1_policy()->is_young_list_full();
6473   if (force || !young_list_full) {
6474     HeapRegion* new_alloc_region = new_region(word_size,
6475                                               false /* is_old */,
6476                                               false /* do_expand */);
6477     if (new_alloc_region != NULL) {
6478       set_region_short_lived_locked(new_alloc_region);
6479       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6480       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6481       return new_alloc_region;
6482     }
6483   }
6484   return NULL;
6485 }
6486 
6487 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6488                                                   size_t allocated_bytes) {
6489   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6490   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6491 
6492   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6493   _allocator->increase_used(allocated_bytes);
6494   _hr_printer.retire(alloc_region);
6495   // We update the eden sizes here, when the region is retired,
6496   // instead of when it's allocated, since this is the point that its
6497   // used space has been recored in _summary_bytes_used.
6498   g1mm()->update_eden_size();
6499 }
6500 
6501 void G1CollectedHeap::set_par_threads() {
6502   // Don't change the number of workers.  Use the value previously set
6503   // in the workgroup.
6504   uint n_workers = workers()->active_workers();
6505   assert(UseDynamicNumberOfGCThreads ||
6506            n_workers == workers()->total_workers(),
6507       "Otherwise should be using the total number of workers");
6508   if (n_workers == 0) {
6509     assert(false, "Should have been set in prior evacuation pause.");
6510     n_workers = ParallelGCThreads;
6511     workers()->set_active_workers(n_workers);
6512   }
6513   set_par_threads(n_workers);
6514 }
6515 
6516 // Methods for the GC alloc regions
6517 
6518 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6519                                                  uint count,
6520                                                  GCAllocPurpose ap) {
6521   assert(FreeList_lock->owned_by_self(), "pre-condition");
6522 
6523   if (count < g1_policy()->max_regions(ap)) {
6524     bool survivor = (ap == GCAllocForSurvived);
6525     HeapRegion* new_alloc_region = new_region(word_size,
6526                                               !survivor,
6527                                               true /* do_expand */);
6528     if (new_alloc_region != NULL) {
6529       // We really only need to do this for old regions given that we
6530       // should never scan survivors. But it doesn't hurt to do it
6531       // for survivors too.
6532       new_alloc_region->record_top_and_timestamp();
6533       if (survivor) {
6534         new_alloc_region->set_survivor();
6535         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6536         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6537       } else {
6538         new_alloc_region->set_old();
6539         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6540         check_bitmaps("Old Region Allocation", new_alloc_region);
6541       }
6542       bool during_im = g1_policy()->during_initial_mark_pause();
6543       new_alloc_region->note_start_of_copying(during_im);
6544       return new_alloc_region;
6545     } else {
6546       g1_policy()->note_alloc_region_limit_reached(ap);
6547     }
6548   }
6549   return NULL;
6550 }
6551 
6552 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6553                                              size_t allocated_bytes,
6554                                              GCAllocPurpose ap) {
6555   bool during_im = g1_policy()->during_initial_mark_pause();
6556   alloc_region->note_end_of_copying(during_im);
6557   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6558   if (ap == GCAllocForSurvived) {
6559     young_list()->add_survivor_region(alloc_region);
6560   } else {
6561     _old_set.add(alloc_region);
6562   }
6563   _hr_printer.retire(alloc_region);
6564 }
6565 
6566 // Heap region set verification
6567 
6568 class VerifyRegionListsClosure : public HeapRegionClosure {
6569 private:
6570   HeapRegionSet*   _old_set;
6571   HeapRegionSet*   _humongous_set;
6572   HeapRegionManager*   _hrm;
6573 
6574 public:
6575   HeapRegionSetCount _old_count;
6576   HeapRegionSetCount _humongous_count;
6577   HeapRegionSetCount _free_count;
6578 
6579   VerifyRegionListsClosure(HeapRegionSet* old_set,
6580                            HeapRegionSet* humongous_set,
6581                            HeapRegionManager* hrm) :
6582     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6583     _old_count(), _humongous_count(), _free_count(){ }
6584 
6585   bool doHeapRegion(HeapRegion* hr) {
6586     if (hr->is_continues_humongous()) {
6587       return false;
6588     }
6589 
6590     if (hr->is_young()) {
6591       // TODO
6592     } else if (hr->is_starts_humongous()) {
6593       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6594       _humongous_count.increment(1u, hr->capacity());
6595     } else if (hr->is_empty()) {
6596       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6597       _free_count.increment(1u, hr->capacity());
6598     } else if (hr->is_old()) {
6599       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6600       _old_count.increment(1u, hr->capacity());
6601     } else {
6602       ShouldNotReachHere();
6603     }
6604     return false;
6605   }
6606 
6607   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6608     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6609     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6610         old_set->total_capacity_bytes(), _old_count.capacity()));
6611 
6612     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6613     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6614         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6615 
6616     guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
6617     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6618         free_list->total_capacity_bytes(), _free_count.capacity()));
6619   }
6620 };
6621 
6622 void G1CollectedHeap::verify_region_sets() {
6623   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6624 
6625   // First, check the explicit lists.
6626   _hrm.verify();
6627   {
6628     // Given that a concurrent operation might be adding regions to
6629     // the secondary free list we have to take the lock before
6630     // verifying it.
6631     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6632     _secondary_free_list.verify_list();
6633   }
6634 
6635   // If a concurrent region freeing operation is in progress it will
6636   // be difficult to correctly attributed any free regions we come
6637   // across to the correct free list given that they might belong to
6638   // one of several (free_list, secondary_free_list, any local lists,
6639   // etc.). So, if that's the case we will skip the rest of the
6640   // verification operation. Alternatively, waiting for the concurrent
6641   // operation to complete will have a non-trivial effect on the GC's
6642   // operation (no concurrent operation will last longer than the
6643   // interval between two calls to verification) and it might hide
6644   // any issues that we would like to catch during testing.
6645   if (free_regions_coming()) {
6646     return;
6647   }
6648 
6649   // Make sure we append the secondary_free_list on the free_list so
6650   // that all free regions we will come across can be safely
6651   // attributed to the free_list.
6652   append_secondary_free_list_if_not_empty_with_lock();
6653 
6654   // Finally, make sure that the region accounting in the lists is
6655   // consistent with what we see in the heap.
6656 
6657   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6658   heap_region_iterate(&cl);
6659   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6660 }
6661 
6662 // Optimized nmethod scanning
6663 
6664 class RegisterNMethodOopClosure: public OopClosure {
6665   G1CollectedHeap* _g1h;
6666   nmethod* _nm;
6667 
6668   template <class T> void do_oop_work(T* p) {
6669     T heap_oop = oopDesc::load_heap_oop(p);
6670     if (!oopDesc::is_null(heap_oop)) {
6671       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6672       HeapRegion* hr = _g1h->heap_region_containing(obj);
6673       assert(!hr->is_continues_humongous(),
6674              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6675                      " starting at "HR_FORMAT,
6676                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6677 
6678       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6679       hr->add_strong_code_root_locked(_nm);
6680     }
6681   }
6682 
6683 public:
6684   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6685     _g1h(g1h), _nm(nm) {}
6686 
6687   void do_oop(oop* p)       { do_oop_work(p); }
6688   void do_oop(narrowOop* p) { do_oop_work(p); }
6689 };
6690 
6691 class UnregisterNMethodOopClosure: public OopClosure {
6692   G1CollectedHeap* _g1h;
6693   nmethod* _nm;
6694 
6695   template <class T> void do_oop_work(T* p) {
6696     T heap_oop = oopDesc::load_heap_oop(p);
6697     if (!oopDesc::is_null(heap_oop)) {
6698       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6699       HeapRegion* hr = _g1h->heap_region_containing(obj);
6700       assert(!hr->is_continues_humongous(),
6701              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6702                      " starting at "HR_FORMAT,
6703                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6704 
6705       hr->remove_strong_code_root(_nm);
6706     }
6707   }
6708 
6709 public:
6710   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6711     _g1h(g1h), _nm(nm) {}
6712 
6713   void do_oop(oop* p)       { do_oop_work(p); }
6714   void do_oop(narrowOop* p) { do_oop_work(p); }
6715 };
6716 
6717 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6718   CollectedHeap::register_nmethod(nm);
6719 
6720   guarantee(nm != NULL, "sanity");
6721   RegisterNMethodOopClosure reg_cl(this, nm);
6722   nm->oops_do(&reg_cl);
6723 }
6724 
6725 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6726   CollectedHeap::unregister_nmethod(nm);
6727 
6728   guarantee(nm != NULL, "sanity");
6729   UnregisterNMethodOopClosure reg_cl(this, nm);
6730   nm->oops_do(&reg_cl, true);
6731 }
6732 
6733 void G1CollectedHeap::purge_code_root_memory() {
6734   double purge_start = os::elapsedTime();
6735   G1CodeRootSet::purge();
6736   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6737   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6738 }
6739 
6740 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6741   G1CollectedHeap* _g1h;
6742 
6743 public:
6744   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6745     _g1h(g1h) {}
6746 
6747   void do_code_blob(CodeBlob* cb) {
6748     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6749     if (nm == NULL) {
6750       return;
6751     }
6752 
6753     if (ScavengeRootsInCode) {
6754       _g1h->register_nmethod(nm);
6755     }
6756   }
6757 };
6758 
6759 void G1CollectedHeap::rebuild_strong_code_roots() {
6760   RebuildStrongCodeRootClosure blob_cl(this);
6761   CodeCache::blobs_do(&blob_cl);
6762 }
--- EOF ---