1 /*
   2  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "code/codeCache.hpp"
  27 #include "code/icBuffer.hpp"
  28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  36 #include "gc_implementation/g1/g1EvacFailure.hpp"
  37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  38 #include "gc_implementation/g1/g1Log.hpp"
  39 #include "gc_implementation/g1/g1MarkSweep.hpp"
  40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  42 #include "gc_implementation/g1/g1YCTypes.hpp"
  43 #include "gc_implementation/g1/heapRegion.inline.hpp"
  44 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  46 #include "gc_implementation/g1/vm_operations_g1.hpp"
  47 #include "gc_implementation/shared/gcHeapSummary.hpp"
  48 #include "gc_implementation/shared/gcTimer.hpp"
  49 #include "gc_implementation/shared/gcTrace.hpp"
  50 #include "gc_implementation/shared/gcTraceTime.hpp"
  51 #include "gc_implementation/shared/isGCActiveMark.hpp"
  52 #include "memory/gcLocker.inline.hpp"
  53 #include "memory/genOopClosures.inline.hpp"
  54 #include "memory/generationSpec.hpp"
  55 #include "memory/referenceProcessor.hpp"
  56 #include "oops/oop.inline.hpp"
  57 #include "oops/oop.pcgc.inline.hpp"
  58 #include "runtime/vmThread.hpp"
  59 
  60 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  61 
  62 // turn it on so that the contents of the young list (scan-only /
  63 // to-be-collected) are printed at "strategic" points before / during
  64 // / after the collection --- this is useful for debugging
  65 #define YOUNG_LIST_VERBOSE 0
  66 // CURRENT STATUS
  67 // This file is under construction.  Search for "FIXME".
  68 
  69 // INVARIANTS/NOTES
  70 //
  71 // All allocation activity covered by the G1CollectedHeap interface is
  72 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  73 // and allocate_new_tlab, which are the "entry" points to the
  74 // allocation code from the rest of the JVM.  (Note that this does not
  75 // apply to TLAB allocation, which is not part of this interface: it
  76 // is done by clients of this interface.)
  77 
  78 // Notes on implementation of parallelism in different tasks.
  79 //
  80 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  81 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  82 // It does use run_task() which sets _n_workers in the task.
  83 // G1ParTask executes g1_process_strong_roots() ->
  84 // SharedHeap::process_strong_roots() which calls eventually to
  85 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  86 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  87 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  88 //
  89 
  90 // Local to this file.
  91 
  92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  93   SuspendibleThreadSet* _sts;
  94   G1RemSet* _g1rs;
  95   ConcurrentG1Refine* _cg1r;
  96   bool _concurrent;
  97 public:
  98   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  99                               G1RemSet* g1rs,
 100                               ConcurrentG1Refine* cg1r) :
 101     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
 102   {}
 103   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 104     bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
 105     // This path is executed by the concurrent refine or mutator threads,
 106     // concurrently, and so we do not care if card_ptr contains references
 107     // that point into the collection set.
 108     assert(!oops_into_cset, "should be");
 109 
 110     if (_concurrent && _sts->should_yield()) {
 111       // Caller will actually yield.
 112       return false;
 113     }
 114     // Otherwise, we finished successfully; return true.
 115     return true;
 116   }
 117   void set_concurrent(bool b) { _concurrent = b; }
 118 };
 119 
 120 
 121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 122   int _calls;
 123   G1CollectedHeap* _g1h;
 124   CardTableModRefBS* _ctbs;
 125   int _histo[256];
 126 public:
 127   ClearLoggedCardTableEntryClosure() :
 128     _calls(0)
 129   {
 130     _g1h = G1CollectedHeap::heap();
 131     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 132     for (int i = 0; i < 256; i++) _histo[i] = 0;
 133   }
 134   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 135     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 136       _calls++;
 137       unsigned char* ujb = (unsigned char*)card_ptr;
 138       int ind = (int)(*ujb);
 139       _histo[ind]++;
 140       *card_ptr = -1;
 141     }
 142     return true;
 143   }
 144   int calls() { return _calls; }
 145   void print_histo() {
 146     gclog_or_tty->print_cr("Card table value histogram:");
 147     for (int i = 0; i < 256; i++) {
 148       if (_histo[i] != 0) {
 149         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 150       }
 151     }
 152   }
 153 };
 154 
 155 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 156   int _calls;
 157   G1CollectedHeap* _g1h;
 158   CardTableModRefBS* _ctbs;
 159 public:
 160   RedirtyLoggedCardTableEntryClosure() :
 161     _calls(0)
 162   {
 163     _g1h = G1CollectedHeap::heap();
 164     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 165   }
 166   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 167     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 168       _calls++;
 169       *card_ptr = 0;
 170     }
 171     return true;
 172   }
 173   int calls() { return _calls; }
 174 };
 175 
 176 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 177 public:
 178   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 179     *card_ptr = CardTableModRefBS::dirty_card_val();
 180     return true;
 181   }
 182 };
 183 
 184 YoungList::YoungList(G1CollectedHeap* g1h) :
 185     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 186     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 187   guarantee(check_list_empty(false), "just making sure...");
 188 }
 189 
 190 void YoungList::push_region(HeapRegion *hr) {
 191   assert(!hr->is_young(), "should not already be young");
 192   assert(hr->get_next_young_region() == NULL, "cause it should!");
 193 
 194   hr->set_next_young_region(_head);
 195   _head = hr;
 196 
 197   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 198   ++_length;
 199 }
 200 
 201 void YoungList::add_survivor_region(HeapRegion* hr) {
 202   assert(hr->is_survivor(), "should be flagged as survivor region");
 203   assert(hr->get_next_young_region() == NULL, "cause it should!");
 204 
 205   hr->set_next_young_region(_survivor_head);
 206   if (_survivor_head == NULL) {
 207     _survivor_tail = hr;
 208   }
 209   _survivor_head = hr;
 210   ++_survivor_length;
 211 }
 212 
 213 void YoungList::empty_list(HeapRegion* list) {
 214   while (list != NULL) {
 215     HeapRegion* next = list->get_next_young_region();
 216     list->set_next_young_region(NULL);
 217     list->uninstall_surv_rate_group();
 218     list->set_not_young();
 219     list = next;
 220   }
 221 }
 222 
 223 void YoungList::empty_list() {
 224   assert(check_list_well_formed(), "young list should be well formed");
 225 
 226   empty_list(_head);
 227   _head = NULL;
 228   _length = 0;
 229 
 230   empty_list(_survivor_head);
 231   _survivor_head = NULL;
 232   _survivor_tail = NULL;
 233   _survivor_length = 0;
 234 
 235   _last_sampled_rs_lengths = 0;
 236 
 237   assert(check_list_empty(false), "just making sure...");
 238 }
 239 
 240 bool YoungList::check_list_well_formed() {
 241   bool ret = true;
 242 
 243   uint length = 0;
 244   HeapRegion* curr = _head;
 245   HeapRegion* last = NULL;
 246   while (curr != NULL) {
 247     if (!curr->is_young()) {
 248       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 249                              "incorrectly tagged (y: %d, surv: %d)",
 250                              curr->bottom(), curr->end(),
 251                              curr->is_young(), curr->is_survivor());
 252       ret = false;
 253     }
 254     ++length;
 255     last = curr;
 256     curr = curr->get_next_young_region();
 257   }
 258   ret = ret && (length == _length);
 259 
 260   if (!ret) {
 261     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 262     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 263                            length, _length);
 264   }
 265 
 266   return ret;
 267 }
 268 
 269 bool YoungList::check_list_empty(bool check_sample) {
 270   bool ret = true;
 271 
 272   if (_length != 0) {
 273     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 274                   _length);
 275     ret = false;
 276   }
 277   if (check_sample && _last_sampled_rs_lengths != 0) {
 278     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 279     ret = false;
 280   }
 281   if (_head != NULL) {
 282     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 283     ret = false;
 284   }
 285   if (!ret) {
 286     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 287   }
 288 
 289   return ret;
 290 }
 291 
 292 void
 293 YoungList::rs_length_sampling_init() {
 294   _sampled_rs_lengths = 0;
 295   _curr               = _head;
 296 }
 297 
 298 bool
 299 YoungList::rs_length_sampling_more() {
 300   return _curr != NULL;
 301 }
 302 
 303 void
 304 YoungList::rs_length_sampling_next() {
 305   assert( _curr != NULL, "invariant" );
 306   size_t rs_length = _curr->rem_set()->occupied();
 307 
 308   _sampled_rs_lengths += rs_length;
 309 
 310   // The current region may not yet have been added to the
 311   // incremental collection set (it gets added when it is
 312   // retired as the current allocation region).
 313   if (_curr->in_collection_set()) {
 314     // Update the collection set policy information for this region
 315     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 316   }
 317 
 318   _curr = _curr->get_next_young_region();
 319   if (_curr == NULL) {
 320     _last_sampled_rs_lengths = _sampled_rs_lengths;
 321     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 322   }
 323 }
 324 
 325 void
 326 YoungList::reset_auxilary_lists() {
 327   guarantee( is_empty(), "young list should be empty" );
 328   assert(check_list_well_formed(), "young list should be well formed");
 329 
 330   // Add survivor regions to SurvRateGroup.
 331   _g1h->g1_policy()->note_start_adding_survivor_regions();
 332   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 333 
 334   int young_index_in_cset = 0;
 335   for (HeapRegion* curr = _survivor_head;
 336        curr != NULL;
 337        curr = curr->get_next_young_region()) {
 338     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 339 
 340     // The region is a non-empty survivor so let's add it to
 341     // the incremental collection set for the next evacuation
 342     // pause.
 343     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 344     young_index_in_cset += 1;
 345   }
 346   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 347   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 348 
 349   _head   = _survivor_head;
 350   _length = _survivor_length;
 351   if (_survivor_head != NULL) {
 352     assert(_survivor_tail != NULL, "cause it shouldn't be");
 353     assert(_survivor_length > 0, "invariant");
 354     _survivor_tail->set_next_young_region(NULL);
 355   }
 356 
 357   // Don't clear the survivor list handles until the start of
 358   // the next evacuation pause - we need it in order to re-tag
 359   // the survivor regions from this evacuation pause as 'young'
 360   // at the start of the next.
 361 
 362   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 363 
 364   assert(check_list_well_formed(), "young list should be well formed");
 365 }
 366 
 367 void YoungList::print() {
 368   HeapRegion* lists[] = {_head,   _survivor_head};
 369   const char* names[] = {"YOUNG", "SURVIVOR"};
 370 
 371   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 372     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 373     HeapRegion *curr = lists[list];
 374     if (curr == NULL)
 375       gclog_or_tty->print_cr("  empty");
 376     while (curr != NULL) {
 377       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 378                              HR_FORMAT_PARAMS(curr),
 379                              curr->prev_top_at_mark_start(),
 380                              curr->next_top_at_mark_start(),
 381                              curr->age_in_surv_rate_group_cond());
 382       curr = curr->get_next_young_region();
 383     }
 384   }
 385 
 386   gclog_or_tty->print_cr("");
 387 }
 388 
 389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 390 {
 391   // Claim the right to put the region on the dirty cards region list
 392   // by installing a self pointer.
 393   HeapRegion* next = hr->get_next_dirty_cards_region();
 394   if (next == NULL) {
 395     HeapRegion* res = (HeapRegion*)
 396       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 397                           NULL);
 398     if (res == NULL) {
 399       HeapRegion* head;
 400       do {
 401         // Put the region to the dirty cards region list.
 402         head = _dirty_cards_region_list;
 403         next = (HeapRegion*)
 404           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 405         if (next == head) {
 406           assert(hr->get_next_dirty_cards_region() == hr,
 407                  "hr->get_next_dirty_cards_region() != hr");
 408           if (next == NULL) {
 409             // The last region in the list points to itself.
 410             hr->set_next_dirty_cards_region(hr);
 411           } else {
 412             hr->set_next_dirty_cards_region(next);
 413           }
 414         }
 415       } while (next != head);
 416     }
 417   }
 418 }
 419 
 420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 421 {
 422   HeapRegion* head;
 423   HeapRegion* hr;
 424   do {
 425     head = _dirty_cards_region_list;
 426     if (head == NULL) {
 427       return NULL;
 428     }
 429     HeapRegion* new_head = head->get_next_dirty_cards_region();
 430     if (head == new_head) {
 431       // The last region.
 432       new_head = NULL;
 433     }
 434     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 435                                           head);
 436   } while (hr != head);
 437   assert(hr != NULL, "invariant");
 438   hr->set_next_dirty_cards_region(NULL);
 439   return hr;
 440 }
 441 
 442 void G1CollectedHeap::stop_conc_gc_threads() {
 443   _cg1r->stop();
 444   _cmThread->stop();
 445 }
 446 
 447 #ifdef ASSERT
 448 // A region is added to the collection set as it is retired
 449 // so an address p can point to a region which will be in the
 450 // collection set but has not yet been retired.  This method
 451 // therefore is only accurate during a GC pause after all
 452 // regions have been retired.  It is used for debugging
 453 // to check if an nmethod has references to objects that can
 454 // be move during a partial collection.  Though it can be
 455 // inaccurate, it is sufficient for G1 because the conservative
 456 // implementation of is_scavengable() for G1 will indicate that
 457 // all nmethods must be scanned during a partial collection.
 458 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 459   HeapRegion* hr = heap_region_containing(p);
 460   return hr != NULL && hr->in_collection_set();
 461 }
 462 #endif
 463 
 464 // Returns true if the reference points to an object that
 465 // can move in an incremental collection.
 466 bool G1CollectedHeap::is_scavengable(const void* p) {
 467   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 468   G1CollectorPolicy* g1p = g1h->g1_policy();
 469   HeapRegion* hr = heap_region_containing(p);
 470   if (hr == NULL) {
 471      // null
 472      assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
 473      return false;
 474   } else {
 475     return !hr->isHumongous();
 476   }
 477 }
 478 
 479 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 480   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 481   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
 482 
 483   // Count the dirty cards at the start.
 484   CountNonCleanMemRegionClosure count1(this);
 485   ct_bs->mod_card_iterate(&count1);
 486   int orig_count = count1.n();
 487 
 488   // First clear the logged cards.
 489   ClearLoggedCardTableEntryClosure clear;
 490   dcqs.set_closure(&clear);
 491   dcqs.apply_closure_to_all_completed_buffers();
 492   dcqs.iterate_closure_all_threads(false);
 493   clear.print_histo();
 494 
 495   // Now ensure that there's no dirty cards.
 496   CountNonCleanMemRegionClosure count2(this);
 497   ct_bs->mod_card_iterate(&count2);
 498   if (count2.n() != 0) {
 499     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 500                            count2.n(), orig_count);
 501   }
 502   guarantee(count2.n() == 0, "Card table should be clean.");
 503 
 504   RedirtyLoggedCardTableEntryClosure redirty;
 505   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 506   dcqs.apply_closure_to_all_completed_buffers();
 507   dcqs.iterate_closure_all_threads(false);
 508   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 509                          clear.calls(), orig_count);
 510   guarantee(redirty.calls() == clear.calls(),
 511             "Or else mechanism is broken.");
 512 
 513   CountNonCleanMemRegionClosure count3(this);
 514   ct_bs->mod_card_iterate(&count3);
 515   if (count3.n() != orig_count) {
 516     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 517                            orig_count, count3.n());
 518     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 519   }
 520 
 521   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 522 }
 523 
 524 // Private class members.
 525 
 526 G1CollectedHeap* G1CollectedHeap::_g1h;
 527 
 528 // Private methods.
 529 
 530 HeapRegion*
 531 G1CollectedHeap::new_region_try_secondary_free_list() {
 532   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 533   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 534     if (!_secondary_free_list.is_empty()) {
 535       if (G1ConcRegionFreeingVerbose) {
 536         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 537                                "secondary_free_list has %u entries",
 538                                _secondary_free_list.length());
 539       }
 540       // It looks as if there are free regions available on the
 541       // secondary_free_list. Let's move them to the free_list and try
 542       // again to allocate from it.
 543       append_secondary_free_list();
 544 
 545       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 546              "empty we should have moved at least one entry to the free_list");
 547       HeapRegion* res = _free_list.remove_head();
 548       if (G1ConcRegionFreeingVerbose) {
 549         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 550                                "allocated "HR_FORMAT" from secondary_free_list",
 551                                HR_FORMAT_PARAMS(res));
 552       }
 553       return res;
 554     }
 555 
 556     // Wait here until we get notified either when (a) there are no
 557     // more free regions coming or (b) some regions have been moved on
 558     // the secondary_free_list.
 559     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 560   }
 561 
 562   if (G1ConcRegionFreeingVerbose) {
 563     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 564                            "could not allocate from secondary_free_list");
 565   }
 566   return NULL;
 567 }
 568 
 569 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 570   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 571          "the only time we use this to allocate a humongous region is "
 572          "when we are allocating a single humongous region");
 573 
 574   HeapRegion* res;
 575   if (G1StressConcRegionFreeing) {
 576     if (!_secondary_free_list.is_empty()) {
 577       if (G1ConcRegionFreeingVerbose) {
 578         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 579                                "forced to look at the secondary_free_list");
 580       }
 581       res = new_region_try_secondary_free_list();
 582       if (res != NULL) {
 583         return res;
 584       }
 585     }
 586   }
 587   res = _free_list.remove_head_or_null();
 588   if (res == NULL) {
 589     if (G1ConcRegionFreeingVerbose) {
 590       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 591                              "res == NULL, trying the secondary_free_list");
 592     }
 593     res = new_region_try_secondary_free_list();
 594   }
 595   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 596     // Currently, only attempts to allocate GC alloc regions set
 597     // do_expand to true. So, we should only reach here during a
 598     // safepoint. If this assumption changes we might have to
 599     // reconsider the use of _expand_heap_after_alloc_failure.
 600     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 601 
 602     ergo_verbose1(ErgoHeapSizing,
 603                   "attempt heap expansion",
 604                   ergo_format_reason("region allocation request failed")
 605                   ergo_format_byte("allocation request"),
 606                   word_size * HeapWordSize);
 607     if (expand(word_size * HeapWordSize)) {
 608       // Given that expand() succeeded in expanding the heap, and we
 609       // always expand the heap by an amount aligned to the heap
 610       // region size, the free list should in theory not be empty. So
 611       // it would probably be OK to use remove_head(). But the extra
 612       // check for NULL is unlikely to be a performance issue here (we
 613       // just expanded the heap!) so let's just be conservative and
 614       // use remove_head_or_null().
 615       res = _free_list.remove_head_or_null();
 616     } else {
 617       _expand_heap_after_alloc_failure = false;
 618     }
 619   }
 620   return res;
 621 }
 622 
 623 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 624                                                         size_t word_size) {
 625   assert(isHumongous(word_size), "word_size should be humongous");
 626   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 627 
 628   uint first = G1_NULL_HRS_INDEX;
 629   if (num_regions == 1) {
 630     // Only one region to allocate, no need to go through the slower
 631     // path. The caller will attempt the expansion if this fails, so
 632     // let's not try to expand here too.
 633     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 634     if (hr != NULL) {
 635       first = hr->hrs_index();
 636     } else {
 637       first = G1_NULL_HRS_INDEX;
 638     }
 639   } else {
 640     // We can't allocate humongous regions while cleanupComplete() is
 641     // running, since some of the regions we find to be empty might not
 642     // yet be added to the free list and it is not straightforward to
 643     // know which list they are on so that we can remove them. Note
 644     // that we only need to do this if we need to allocate more than
 645     // one region to satisfy the current humongous allocation
 646     // request. If we are only allocating one region we use the common
 647     // region allocation code (see above).
 648     wait_while_free_regions_coming();
 649     append_secondary_free_list_if_not_empty_with_lock();
 650 
 651     if (free_regions() >= num_regions) {
 652       first = _hrs.find_contiguous(num_regions);
 653       if (first != G1_NULL_HRS_INDEX) {
 654         for (uint i = first; i < first + num_regions; ++i) {
 655           HeapRegion* hr = region_at(i);
 656           assert(hr->is_empty(), "sanity");
 657           assert(is_on_master_free_list(hr), "sanity");
 658           hr->set_pending_removal(true);
 659         }
 660         _free_list.remove_all_pending(num_regions);
 661       }
 662     }
 663   }
 664   return first;
 665 }
 666 
 667 HeapWord*
 668 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 669                                                            uint num_regions,
 670                                                            size_t word_size) {
 671   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 672   assert(isHumongous(word_size), "word_size should be humongous");
 673   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 674 
 675   // Index of last region in the series + 1.
 676   uint last = first + num_regions;
 677 
 678   // We need to initialize the region(s) we just discovered. This is
 679   // a bit tricky given that it can happen concurrently with
 680   // refinement threads refining cards on these regions and
 681   // potentially wanting to refine the BOT as they are scanning
 682   // those cards (this can happen shortly after a cleanup; see CR
 683   // 6991377). So we have to set up the region(s) carefully and in
 684   // a specific order.
 685 
 686   // The word size sum of all the regions we will allocate.
 687   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 688   assert(word_size <= word_size_sum, "sanity");
 689 
 690   // This will be the "starts humongous" region.
 691   HeapRegion* first_hr = region_at(first);
 692   // The header of the new object will be placed at the bottom of
 693   // the first region.
 694   HeapWord* new_obj = first_hr->bottom();
 695   // This will be the new end of the first region in the series that
 696   // should also match the end of the last region in the series.
 697   HeapWord* new_end = new_obj + word_size_sum;
 698   // This will be the new top of the first region that will reflect
 699   // this allocation.
 700   HeapWord* new_top = new_obj + word_size;
 701 
 702   // First, we need to zero the header of the space that we will be
 703   // allocating. When we update top further down, some refinement
 704   // threads might try to scan the region. By zeroing the header we
 705   // ensure that any thread that will try to scan the region will
 706   // come across the zero klass word and bail out.
 707   //
 708   // NOTE: It would not have been correct to have used
 709   // CollectedHeap::fill_with_object() and make the space look like
 710   // an int array. The thread that is doing the allocation will
 711   // later update the object header to a potentially different array
 712   // type and, for a very short period of time, the klass and length
 713   // fields will be inconsistent. This could cause a refinement
 714   // thread to calculate the object size incorrectly.
 715   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 716 
 717   // We will set up the first region as "starts humongous". This
 718   // will also update the BOT covering all the regions to reflect
 719   // that there is a single object that starts at the bottom of the
 720   // first region.
 721   first_hr->set_startsHumongous(new_top, new_end);
 722 
 723   // Then, if there are any, we will set up the "continues
 724   // humongous" regions.
 725   HeapRegion* hr = NULL;
 726   for (uint i = first + 1; i < last; ++i) {
 727     hr = region_at(i);
 728     hr->set_continuesHumongous(first_hr);
 729   }
 730   // If we have "continues humongous" regions (hr != NULL), then the
 731   // end of the last one should match new_end.
 732   assert(hr == NULL || hr->end() == new_end, "sanity");
 733 
 734   // Up to this point no concurrent thread would have been able to
 735   // do any scanning on any region in this series. All the top
 736   // fields still point to bottom, so the intersection between
 737   // [bottom,top] and [card_start,card_end] will be empty. Before we
 738   // update the top fields, we'll do a storestore to make sure that
 739   // no thread sees the update to top before the zeroing of the
 740   // object header and the BOT initialization.
 741   OrderAccess::storestore();
 742 
 743   // Now that the BOT and the object header have been initialized,
 744   // we can update top of the "starts humongous" region.
 745   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 746          "new_top should be in this region");
 747   first_hr->set_top(new_top);
 748   if (_hr_printer.is_active()) {
 749     HeapWord* bottom = first_hr->bottom();
 750     HeapWord* end = first_hr->orig_end();
 751     if ((first + 1) == last) {
 752       // the series has a single humongous region
 753       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 754     } else {
 755       // the series has more than one humongous regions
 756       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 757     }
 758   }
 759 
 760   // Now, we will update the top fields of the "continues humongous"
 761   // regions. The reason we need to do this is that, otherwise,
 762   // these regions would look empty and this will confuse parts of
 763   // G1. For example, the code that looks for a consecutive number
 764   // of empty regions will consider them empty and try to
 765   // re-allocate them. We can extend is_empty() to also include
 766   // !continuesHumongous(), but it is easier to just update the top
 767   // fields here. The way we set top for all regions (i.e., top ==
 768   // end for all regions but the last one, top == new_top for the
 769   // last one) is actually used when we will free up the humongous
 770   // region in free_humongous_region().
 771   hr = NULL;
 772   for (uint i = first + 1; i < last; ++i) {
 773     hr = region_at(i);
 774     if ((i + 1) == last) {
 775       // last continues humongous region
 776       assert(hr->bottom() < new_top && new_top <= hr->end(),
 777              "new_top should fall on this region");
 778       hr->set_top(new_top);
 779       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 780     } else {
 781       // not last one
 782       assert(new_top > hr->end(), "new_top should be above this region");
 783       hr->set_top(hr->end());
 784       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 785     }
 786   }
 787   // If we have continues humongous regions (hr != NULL), then the
 788   // end of the last one should match new_end and its top should
 789   // match new_top.
 790   assert(hr == NULL ||
 791          (hr->end() == new_end && hr->top() == new_top), "sanity");
 792 
 793   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 794   _summary_bytes_used += first_hr->used();
 795   _humongous_set.add(first_hr);
 796 
 797   return new_obj;
 798 }
 799 
 800 // If could fit into free regions w/o expansion, try.
 801 // Otherwise, if can expand, do so.
 802 // Otherwise, if using ex regions might help, try with ex given back.
 803 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 804   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 805 
 806   verify_region_sets_optional();
 807 
 808   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 809   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 810   uint x_num = expansion_regions();
 811   uint fs = _hrs.free_suffix();
 812   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 813   if (first == G1_NULL_HRS_INDEX) {
 814     // The only thing we can do now is attempt expansion.
 815     if (fs + x_num >= num_regions) {
 816       // If the number of regions we're trying to allocate for this
 817       // object is at most the number of regions in the free suffix,
 818       // then the call to humongous_obj_allocate_find_first() above
 819       // should have succeeded and we wouldn't be here.
 820       //
 821       // We should only be trying to expand when the free suffix is
 822       // not sufficient for the object _and_ we have some expansion
 823       // room available.
 824       assert(num_regions > fs, "earlier allocation should have succeeded");
 825 
 826       ergo_verbose1(ErgoHeapSizing,
 827                     "attempt heap expansion",
 828                     ergo_format_reason("humongous allocation request failed")
 829                     ergo_format_byte("allocation request"),
 830                     word_size * HeapWordSize);
 831       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 832         // Even though the heap was expanded, it might not have
 833         // reached the desired size. So, we cannot assume that the
 834         // allocation will succeed.
 835         first = humongous_obj_allocate_find_first(num_regions, word_size);
 836       }
 837     }
 838   }
 839 
 840   HeapWord* result = NULL;
 841   if (first != G1_NULL_HRS_INDEX) {
 842     result =
 843       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 844     assert(result != NULL, "it should always return a valid result");
 845 
 846     // A successful humongous object allocation changes the used space
 847     // information of the old generation so we need to recalculate the
 848     // sizes and update the jstat counters here.
 849     g1mm()->update_sizes();
 850   }
 851 
 852   verify_region_sets_optional();
 853 
 854   return result;
 855 }
 856 
 857 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 858   assert_heap_not_locked_and_not_at_safepoint();
 859   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 860 
 861   unsigned int dummy_gc_count_before;
 862   int dummy_gclocker_retry_count = 0;
 863   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 864 }
 865 
 866 HeapWord*
 867 G1CollectedHeap::mem_allocate(size_t word_size,
 868                               bool*  gc_overhead_limit_was_exceeded) {
 869   assert_heap_not_locked_and_not_at_safepoint();
 870 
 871   // Loop until the allocation is satisfied, or unsatisfied after GC.
 872   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 873     unsigned int gc_count_before;
 874 
 875     HeapWord* result = NULL;
 876     if (!isHumongous(word_size)) {
 877       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 878     } else {
 879       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 880     }
 881     if (result != NULL) {
 882       return result;
 883     }
 884 
 885     // Create the garbage collection operation...
 886     VM_G1CollectForAllocation op(gc_count_before, word_size);
 887     // ...and get the VM thread to execute it.
 888     VMThread::execute(&op);
 889 
 890     if (op.prologue_succeeded() && op.pause_succeeded()) {
 891       // If the operation was successful we'll return the result even
 892       // if it is NULL. If the allocation attempt failed immediately
 893       // after a Full GC, it's unlikely we'll be able to allocate now.
 894       HeapWord* result = op.result();
 895       if (result != NULL && !isHumongous(word_size)) {
 896         // Allocations that take place on VM operations do not do any
 897         // card dirtying and we have to do it here. We only have to do
 898         // this for non-humongous allocations, though.
 899         dirty_young_block(result, word_size);
 900       }
 901       return result;
 902     } else {
 903       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 904         return NULL;
 905       }
 906       assert(op.result() == NULL,
 907              "the result should be NULL if the VM op did not succeed");
 908     }
 909 
 910     // Give a warning if we seem to be looping forever.
 911     if ((QueuedAllocationWarningCount > 0) &&
 912         (try_count % QueuedAllocationWarningCount == 0)) {
 913       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 914     }
 915   }
 916 
 917   ShouldNotReachHere();
 918   return NULL;
 919 }
 920 
 921 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 922                                            unsigned int *gc_count_before_ret,
 923                                            int* gclocker_retry_count_ret) {
 924   // Make sure you read the note in attempt_allocation_humongous().
 925 
 926   assert_heap_not_locked_and_not_at_safepoint();
 927   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 928          "be called for humongous allocation requests");
 929 
 930   // We should only get here after the first-level allocation attempt
 931   // (attempt_allocation()) failed to allocate.
 932 
 933   // We will loop until a) we manage to successfully perform the
 934   // allocation or b) we successfully schedule a collection which
 935   // fails to perform the allocation. b) is the only case when we'll
 936   // return NULL.
 937   HeapWord* result = NULL;
 938   for (int try_count = 1; /* we'll return */; try_count += 1) {
 939     bool should_try_gc;
 940     unsigned int gc_count_before;
 941 
 942     {
 943       MutexLockerEx x(Heap_lock);
 944 
 945       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 946                                                       false /* bot_updates */);
 947       if (result != NULL) {
 948         return result;
 949       }
 950 
 951       // If we reach here, attempt_allocation_locked() above failed to
 952       // allocate a new region. So the mutator alloc region should be NULL.
 953       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 954 
 955       if (GC_locker::is_active_and_needs_gc()) {
 956         if (g1_policy()->can_expand_young_list()) {
 957           // No need for an ergo verbose message here,
 958           // can_expand_young_list() does this when it returns true.
 959           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 960                                                       false /* bot_updates */);
 961           if (result != NULL) {
 962             return result;
 963           }
 964         }
 965         should_try_gc = false;
 966       } else {
 967         // The GCLocker may not be active but the GCLocker initiated
 968         // GC may not yet have been performed (GCLocker::needs_gc()
 969         // returns true). In this case we do not try this GC and
 970         // wait until the GCLocker initiated GC is performed, and
 971         // then retry the allocation.
 972         if (GC_locker::needs_gc()) {
 973           should_try_gc = false;
 974         } else {
 975           // Read the GC count while still holding the Heap_lock.
 976           gc_count_before = total_collections();
 977           should_try_gc = true;
 978         }
 979       }
 980     }
 981 
 982     if (should_try_gc) {
 983       bool succeeded;
 984       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 985           GCCause::_g1_inc_collection_pause);
 986       if (result != NULL) {
 987         assert(succeeded, "only way to get back a non-NULL result");
 988         return result;
 989       }
 990 
 991       if (succeeded) {
 992         // If we get here we successfully scheduled a collection which
 993         // failed to allocate. No point in trying to allocate
 994         // further. We'll just return NULL.
 995         MutexLockerEx x(Heap_lock);
 996         *gc_count_before_ret = total_collections();
 997         return NULL;
 998       }
 999     } else {
1000       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1001         MutexLockerEx x(Heap_lock);
1002         *gc_count_before_ret = total_collections();
1003         return NULL;
1004       }
1005       // The GCLocker is either active or the GCLocker initiated
1006       // GC has not yet been performed. Stall until it is and
1007       // then retry the allocation.
1008       GC_locker::stall_until_clear();
1009       (*gclocker_retry_count_ret) += 1;
1010     }
1011 
1012     // We can reach here if we were unsuccessful in scheduling a
1013     // collection (because another thread beat us to it) or if we were
1014     // stalled due to the GC locker. In either can we should retry the
1015     // allocation attempt in case another thread successfully
1016     // performed a collection and reclaimed enough space. We do the
1017     // first attempt (without holding the Heap_lock) here and the
1018     // follow-on attempt will be at the start of the next loop
1019     // iteration (after taking the Heap_lock).
1020     result = _mutator_alloc_region.attempt_allocation(word_size,
1021                                                       false /* bot_updates */);
1022     if (result != NULL) {
1023       return result;
1024     }
1025 
1026     // Give a warning if we seem to be looping forever.
1027     if ((QueuedAllocationWarningCount > 0) &&
1028         (try_count % QueuedAllocationWarningCount == 0)) {
1029       warning("G1CollectedHeap::attempt_allocation_slow() "
1030               "retries %d times", try_count);
1031     }
1032   }
1033 
1034   ShouldNotReachHere();
1035   return NULL;
1036 }
1037 
1038 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1039                                           unsigned int * gc_count_before_ret,
1040                                           int* gclocker_retry_count_ret) {
1041   // The structure of this method has a lot of similarities to
1042   // attempt_allocation_slow(). The reason these two were not merged
1043   // into a single one is that such a method would require several "if
1044   // allocation is not humongous do this, otherwise do that"
1045   // conditional paths which would obscure its flow. In fact, an early
1046   // version of this code did use a unified method which was harder to
1047   // follow and, as a result, it had subtle bugs that were hard to
1048   // track down. So keeping these two methods separate allows each to
1049   // be more readable. It will be good to keep these two in sync as
1050   // much as possible.
1051 
1052   assert_heap_not_locked_and_not_at_safepoint();
1053   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1054          "should only be called for humongous allocations");
1055 
1056   // Humongous objects can exhaust the heap quickly, so we should check if we
1057   // need to start a marking cycle at each humongous object allocation. We do
1058   // the check before we do the actual allocation. The reason for doing it
1059   // before the allocation is that we avoid having to keep track of the newly
1060   // allocated memory while we do a GC.
1061   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1062                                            word_size)) {
1063     collect(GCCause::_g1_humongous_allocation);
1064   }
1065 
1066   // We will loop until a) we manage to successfully perform the
1067   // allocation or b) we successfully schedule a collection which
1068   // fails to perform the allocation. b) is the only case when we'll
1069   // return NULL.
1070   HeapWord* result = NULL;
1071   for (int try_count = 1; /* we'll return */; try_count += 1) {
1072     bool should_try_gc;
1073     unsigned int gc_count_before;
1074 
1075     {
1076       MutexLockerEx x(Heap_lock);
1077 
1078       // Given that humongous objects are not allocated in young
1079       // regions, we'll first try to do the allocation without doing a
1080       // collection hoping that there's enough space in the heap.
1081       result = humongous_obj_allocate(word_size);
1082       if (result != NULL) {
1083         return result;
1084       }
1085 
1086       if (GC_locker::is_active_and_needs_gc()) {
1087         should_try_gc = false;
1088       } else {
1089          // The GCLocker may not be active but the GCLocker initiated
1090         // GC may not yet have been performed (GCLocker::needs_gc()
1091         // returns true). In this case we do not try this GC and
1092         // wait until the GCLocker initiated GC is performed, and
1093         // then retry the allocation.
1094         if (GC_locker::needs_gc()) {
1095           should_try_gc = false;
1096         } else {
1097           // Read the GC count while still holding the Heap_lock.
1098           gc_count_before = total_collections();
1099           should_try_gc = true;
1100         }
1101       }
1102     }
1103 
1104     if (should_try_gc) {
1105       // If we failed to allocate the humongous object, we should try to
1106       // do a collection pause (if we're allowed) in case it reclaims
1107       // enough space for the allocation to succeed after the pause.
1108 
1109       bool succeeded;
1110       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1111           GCCause::_g1_humongous_allocation);
1112       if (result != NULL) {
1113         assert(succeeded, "only way to get back a non-NULL result");
1114         return result;
1115       }
1116 
1117       if (succeeded) {
1118         // If we get here we successfully scheduled a collection which
1119         // failed to allocate. No point in trying to allocate
1120         // further. We'll just return NULL.
1121         MutexLockerEx x(Heap_lock);
1122         *gc_count_before_ret = total_collections();
1123         return NULL;
1124       }
1125     } else {
1126       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1127         MutexLockerEx x(Heap_lock);
1128         *gc_count_before_ret = total_collections();
1129         return NULL;
1130       }
1131       // The GCLocker is either active or the GCLocker initiated
1132       // GC has not yet been performed. Stall until it is and
1133       // then retry the allocation.
1134       GC_locker::stall_until_clear();
1135       (*gclocker_retry_count_ret) += 1;
1136     }
1137 
1138     // We can reach here if we were unsuccessful in scheduling a
1139     // collection (because another thread beat us to it) or if we were
1140     // stalled due to the GC locker. In either can we should retry the
1141     // allocation attempt in case another thread successfully
1142     // performed a collection and reclaimed enough space.  Give a
1143     // warning if we seem to be looping forever.
1144 
1145     if ((QueuedAllocationWarningCount > 0) &&
1146         (try_count % QueuedAllocationWarningCount == 0)) {
1147       warning("G1CollectedHeap::attempt_allocation_humongous() "
1148               "retries %d times", try_count);
1149     }
1150   }
1151 
1152   ShouldNotReachHere();
1153   return NULL;
1154 }
1155 
1156 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1157                                        bool expect_null_mutator_alloc_region) {
1158   assert_at_safepoint(true /* should_be_vm_thread */);
1159   assert(_mutator_alloc_region.get() == NULL ||
1160                                              !expect_null_mutator_alloc_region,
1161          "the current alloc region was unexpectedly found to be non-NULL");
1162 
1163   if (!isHumongous(word_size)) {
1164     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1165                                                       false /* bot_updates */);
1166   } else {
1167     HeapWord* result = humongous_obj_allocate(word_size);
1168     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1169       g1_policy()->set_initiate_conc_mark_if_possible();
1170     }
1171     return result;
1172   }
1173 
1174   ShouldNotReachHere();
1175 }
1176 
1177 class PostMCRemSetClearClosure: public HeapRegionClosure {
1178   G1CollectedHeap* _g1h;
1179   ModRefBarrierSet* _mr_bs;
1180 public:
1181   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1182     _g1h(g1h), _mr_bs(mr_bs) {}
1183 
1184   bool doHeapRegion(HeapRegion* r) {
1185     HeapRegionRemSet* hrrs = r->rem_set();
1186 
1187     if (r->continuesHumongous()) {
1188       // We'll assert that the strong code root list and RSet is empty
1189       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1190       assert(hrrs->occupied() == 0, "RSet should be empty");
1191       return false;
1192     }
1193 
1194     _g1h->reset_gc_time_stamps(r);
1195     hrrs->clear();
1196     // You might think here that we could clear just the cards
1197     // corresponding to the used region.  But no: if we leave a dirty card
1198     // in a region we might allocate into, then it would prevent that card
1199     // from being enqueued, and cause it to be missed.
1200     // Re: the performance cost: we shouldn't be doing full GC anyway!
1201     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1202 
1203     return false;
1204   }
1205 };
1206 
1207 void G1CollectedHeap::clear_rsets_post_compaction() {
1208   PostMCRemSetClearClosure rs_clear(this, mr_bs());
1209   heap_region_iterate(&rs_clear);
1210 }
1211 
1212 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1213   G1CollectedHeap*   _g1h;
1214   UpdateRSOopClosure _cl;
1215   int                _worker_i;
1216 public:
1217   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1218     _cl(g1->g1_rem_set(), worker_i),
1219     _worker_i(worker_i),
1220     _g1h(g1)
1221   { }
1222 
1223   bool doHeapRegion(HeapRegion* r) {
1224     if (!r->continuesHumongous()) {
1225       _cl.set_from(r);
1226       r->oop_iterate(&_cl);
1227     }
1228     return false;
1229   }
1230 };
1231 
1232 class ParRebuildRSTask: public AbstractGangTask {
1233   G1CollectedHeap* _g1;
1234 public:
1235   ParRebuildRSTask(G1CollectedHeap* g1)
1236     : AbstractGangTask("ParRebuildRSTask"),
1237       _g1(g1)
1238   { }
1239 
1240   void work(uint worker_id) {
1241     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1242     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1243                                           _g1->workers()->active_workers(),
1244                                          HeapRegion::RebuildRSClaimValue);
1245   }
1246 };
1247 
1248 class PostCompactionPrinterClosure: public HeapRegionClosure {
1249 private:
1250   G1HRPrinter* _hr_printer;
1251 public:
1252   bool doHeapRegion(HeapRegion* hr) {
1253     assert(!hr->is_young(), "not expecting to find young regions");
1254     // We only generate output for non-empty regions.
1255     if (!hr->is_empty()) {
1256       if (!hr->isHumongous()) {
1257         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1258       } else if (hr->startsHumongous()) {
1259         if (hr->region_num() == 1) {
1260           // single humongous region
1261           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1262         } else {
1263           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1264         }
1265       } else {
1266         assert(hr->continuesHumongous(), "only way to get here");
1267         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1268       }
1269     }
1270     return false;
1271   }
1272 
1273   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1274     : _hr_printer(hr_printer) { }
1275 };
1276 
1277 void G1CollectedHeap::print_hrs_post_compaction() {
1278   PostCompactionPrinterClosure cl(hr_printer());
1279   heap_region_iterate(&cl);
1280 }
1281 
1282 bool G1CollectedHeap::do_collection(bool explicit_gc,
1283                                     bool clear_all_soft_refs,
1284                                     size_t word_size) {
1285   assert_at_safepoint(true /* should_be_vm_thread */);
1286 
1287   if (GC_locker::check_active_before_gc()) {
1288     return false;
1289   }
1290 
1291   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1292   gc_timer->register_gc_start(os::elapsed_counter());
1293 
1294   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1295   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1296 
1297   SvcGCMarker sgcm(SvcGCMarker::FULL);
1298   ResourceMark rm;
1299 
1300   print_heap_before_gc();
1301   trace_heap_before_gc(gc_tracer);
1302 
1303   size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1304 
1305   HRSPhaseSetter x(HRSPhaseFullGC);
1306   verify_region_sets_optional();
1307 
1308   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1309                            collector_policy()->should_clear_all_soft_refs();
1310 
1311   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1312 
1313   {
1314     IsGCActiveMark x;
1315 
1316     // Timing
1317     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1318     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1319     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1320 
1321     {
1322       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1323       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1324       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1325 
1326       double start = os::elapsedTime();
1327       g1_policy()->record_full_collection_start();
1328 
1329       // Note: When we have a more flexible GC logging framework that
1330       // allows us to add optional attributes to a GC log record we
1331       // could consider timing and reporting how long we wait in the
1332       // following two methods.
1333       wait_while_free_regions_coming();
1334       // If we start the compaction before the CM threads finish
1335       // scanning the root regions we might trip them over as we'll
1336       // be moving objects / updating references. So let's wait until
1337       // they are done. By telling them to abort, they should complete
1338       // early.
1339       _cm->root_regions()->abort();
1340       _cm->root_regions()->wait_until_scan_finished();
1341       append_secondary_free_list_if_not_empty_with_lock();
1342 
1343       gc_prologue(true);
1344       increment_total_collections(true /* full gc */);
1345       increment_old_marking_cycles_started();
1346 
1347       assert(used() == recalculate_used(), "Should be equal");
1348 
1349       verify_before_gc();
1350 
1351       pre_full_gc_dump(gc_timer);
1352 
1353       COMPILER2_PRESENT(DerivedPointerTable::clear());
1354 
1355       // Disable discovery and empty the discovered lists
1356       // for the CM ref processor.
1357       ref_processor_cm()->disable_discovery();
1358       ref_processor_cm()->abandon_partial_discovery();
1359       ref_processor_cm()->verify_no_references_recorded();
1360 
1361       // Abandon current iterations of concurrent marking and concurrent
1362       // refinement, if any are in progress. We have to do this before
1363       // wait_until_scan_finished() below.
1364       concurrent_mark()->abort();
1365 
1366       // Make sure we'll choose a new allocation region afterwards.
1367       release_mutator_alloc_region();
1368       abandon_gc_alloc_regions();
1369       g1_rem_set()->cleanupHRRS();
1370 
1371       // We should call this after we retire any currently active alloc
1372       // regions so that all the ALLOC / RETIRE events are generated
1373       // before the start GC event.
1374       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1375 
1376       // We may have added regions to the current incremental collection
1377       // set between the last GC or pause and now. We need to clear the
1378       // incremental collection set and then start rebuilding it afresh
1379       // after this full GC.
1380       abandon_collection_set(g1_policy()->inc_cset_head());
1381       g1_policy()->clear_incremental_cset();
1382       g1_policy()->stop_incremental_cset_building();
1383 
1384       tear_down_region_sets(false /* free_list_only */);
1385       g1_policy()->set_gcs_are_young(true);
1386 
1387       // See the comments in g1CollectedHeap.hpp and
1388       // G1CollectedHeap::ref_processing_init() about
1389       // how reference processing currently works in G1.
1390 
1391       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1392       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1393 
1394       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1395       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1396 
1397       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1398       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1399 
1400       // Do collection work
1401       {
1402         HandleMark hm;  // Discard invalid handles created during gc
1403         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1404       }
1405 
1406       assert(free_regions() == 0, "we should not have added any free regions");
1407       rebuild_region_sets(false /* free_list_only */);
1408 
1409       // Enqueue any discovered reference objects that have
1410       // not been removed from the discovered lists.
1411       ref_processor_stw()->enqueue_discovered_references();
1412 
1413       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1414 
1415       MemoryService::track_memory_usage();
1416 
1417       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1418       ref_processor_stw()->verify_no_references_recorded();
1419 
1420       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1421       ClassLoaderDataGraph::purge();
1422       MetaspaceAux::verify_metrics();
1423 
1424       // Note: since we've just done a full GC, concurrent
1425       // marking is no longer active. Therefore we need not
1426       // re-enable reference discovery for the CM ref processor.
1427       // That will be done at the start of the next marking cycle.
1428       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1429       ref_processor_cm()->verify_no_references_recorded();
1430 
1431       reset_gc_time_stamp();
1432       // Since everything potentially moved, we will clear all remembered
1433       // sets, and clear all cards.  Later we will rebuild remembered
1434       // sets. We will also reset the GC time stamps of the regions.
1435       clear_rsets_post_compaction();
1436       check_gc_time_stamps();
1437 
1438       // Resize the heap if necessary.
1439       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1440 
1441       if (_hr_printer.is_active()) {
1442         // We should do this after we potentially resize the heap so
1443         // that all the COMMIT / UNCOMMIT events are generated before
1444         // the end GC event.
1445 
1446         print_hrs_post_compaction();
1447         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1448       }
1449 
1450       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1451       if (hot_card_cache->use_cache()) {
1452         hot_card_cache->reset_card_counts();
1453         hot_card_cache->reset_hot_cache();
1454       }
1455 
1456       // Rebuild remembered sets of all regions.
1457       if (G1CollectedHeap::use_parallel_gc_threads()) {
1458         uint n_workers =
1459           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1460                                                   workers()->active_workers(),
1461                                                   Threads::number_of_non_daemon_threads());
1462         assert(UseDynamicNumberOfGCThreads ||
1463                n_workers == workers()->total_workers(),
1464                "If not dynamic should be using all the  workers");
1465         workers()->set_active_workers(n_workers);
1466         // Set parallel threads in the heap (_n_par_threads) only
1467         // before a parallel phase and always reset it to 0 after
1468         // the phase so that the number of parallel threads does
1469         // no get carried forward to a serial phase where there
1470         // may be code that is "possibly_parallel".
1471         set_par_threads(n_workers);
1472 
1473         ParRebuildRSTask rebuild_rs_task(this);
1474         assert(check_heap_region_claim_values(
1475                HeapRegion::InitialClaimValue), "sanity check");
1476         assert(UseDynamicNumberOfGCThreads ||
1477                workers()->active_workers() == workers()->total_workers(),
1478                "Unless dynamic should use total workers");
1479         // Use the most recent number of  active workers
1480         assert(workers()->active_workers() > 0,
1481                "Active workers not properly set");
1482         set_par_threads(workers()->active_workers());
1483         workers()->run_task(&rebuild_rs_task);
1484         set_par_threads(0);
1485         assert(check_heap_region_claim_values(
1486                HeapRegion::RebuildRSClaimValue), "sanity check");
1487         reset_heap_region_claim_values();
1488       } else {
1489         RebuildRSOutOfRegionClosure rebuild_rs(this);
1490         heap_region_iterate(&rebuild_rs);
1491       }
1492 
1493       // Rebuild the strong code root lists for each region
1494       rebuild_strong_code_roots();
1495 
1496       if (true) { // FIXME
1497         MetaspaceGC::compute_new_size();
1498       }
1499 
1500 #ifdef TRACESPINNING
1501       ParallelTaskTerminator::print_termination_counts();
1502 #endif
1503 
1504       // Discard all rset updates
1505       JavaThread::dirty_card_queue_set().abandon_logs();
1506       assert(!G1DeferredRSUpdate
1507              || (G1DeferredRSUpdate &&
1508                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1509 
1510       _young_list->reset_sampled_info();
1511       // At this point there should be no regions in the
1512       // entire heap tagged as young.
1513       assert(check_young_list_empty(true /* check_heap */),
1514              "young list should be empty at this point");
1515 
1516       // Update the number of full collections that have been completed.
1517       increment_old_marking_cycles_completed(false /* concurrent */);
1518 
1519       _hrs.verify_optional();
1520       verify_region_sets_optional();
1521 
1522       verify_after_gc();
1523 
1524       // Start a new incremental collection set for the next pause
1525       assert(g1_policy()->collection_set() == NULL, "must be");
1526       g1_policy()->start_incremental_cset_building();
1527 
1528       // Clear the _cset_fast_test bitmap in anticipation of adding
1529       // regions to the incremental collection set for the next
1530       // evacuation pause.
1531       clear_cset_fast_test();
1532 
1533       init_mutator_alloc_region();
1534 
1535       double end = os::elapsedTime();
1536       g1_policy()->record_full_collection_end();
1537 
1538       if (G1Log::fine()) {
1539         g1_policy()->print_heap_transition();
1540       }
1541 
1542       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1543       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1544       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1545       // before any GC notifications are raised.
1546       g1mm()->update_sizes();
1547 
1548       gc_epilogue(true);
1549     }
1550 
1551     if (G1Log::finer()) {
1552       g1_policy()->print_detailed_heap_transition(true /* full */);
1553     }
1554 
1555     print_heap_after_gc();
1556     trace_heap_after_gc(gc_tracer);
1557 
1558     post_full_gc_dump(gc_timer);
1559 
1560     gc_timer->register_gc_end(os::elapsed_counter());
1561     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1562   }
1563 
1564   return true;
1565 }
1566 
1567 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1568   // do_collection() will return whether it succeeded in performing
1569   // the GC. Currently, there is no facility on the
1570   // do_full_collection() API to notify the caller than the collection
1571   // did not succeed (e.g., because it was locked out by the GC
1572   // locker). So, right now, we'll ignore the return value.
1573   bool dummy = do_collection(true,                /* explicit_gc */
1574                              clear_all_soft_refs,
1575                              0                    /* word_size */);
1576 }
1577 
1578 // This code is mostly copied from TenuredGeneration.
1579 void
1580 G1CollectedHeap::
1581 resize_if_necessary_after_full_collection(size_t word_size) {
1582   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1583 
1584   // Include the current allocation, if any, and bytes that will be
1585   // pre-allocated to support collections, as "used".
1586   const size_t used_after_gc = used();
1587   const size_t capacity_after_gc = capacity();
1588   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1589 
1590   // This is enforced in arguments.cpp.
1591   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1592          "otherwise the code below doesn't make sense");
1593 
1594   // We don't have floating point command-line arguments
1595   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1596   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1597   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1598   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1599 
1600   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1601   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1602 
1603   // We have to be careful here as these two calculations can overflow
1604   // 32-bit size_t's.
1605   double used_after_gc_d = (double) used_after_gc;
1606   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1607   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1608 
1609   // Let's make sure that they are both under the max heap size, which
1610   // by default will make them fit into a size_t.
1611   double desired_capacity_upper_bound = (double) max_heap_size;
1612   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1613                                     desired_capacity_upper_bound);
1614   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1615                                     desired_capacity_upper_bound);
1616 
1617   // We can now safely turn them into size_t's.
1618   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1619   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1620 
1621   // This assert only makes sense here, before we adjust them
1622   // with respect to the min and max heap size.
1623   assert(minimum_desired_capacity <= maximum_desired_capacity,
1624          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1625                  "maximum_desired_capacity = "SIZE_FORMAT,
1626                  minimum_desired_capacity, maximum_desired_capacity));
1627 
1628   // Should not be greater than the heap max size. No need to adjust
1629   // it with respect to the heap min size as it's a lower bound (i.e.,
1630   // we'll try to make the capacity larger than it, not smaller).
1631   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1632   // Should not be less than the heap min size. No need to adjust it
1633   // with respect to the heap max size as it's an upper bound (i.e.,
1634   // we'll try to make the capacity smaller than it, not greater).
1635   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1636 
1637   if (capacity_after_gc < minimum_desired_capacity) {
1638     // Don't expand unless it's significant
1639     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1640     ergo_verbose4(ErgoHeapSizing,
1641                   "attempt heap expansion",
1642                   ergo_format_reason("capacity lower than "
1643                                      "min desired capacity after Full GC")
1644                   ergo_format_byte("capacity")
1645                   ergo_format_byte("occupancy")
1646                   ergo_format_byte_perc("min desired capacity"),
1647                   capacity_after_gc, used_after_gc,
1648                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1649     expand(expand_bytes);
1650 
1651     // No expansion, now see if we want to shrink
1652   } else if (capacity_after_gc > maximum_desired_capacity) {
1653     // Capacity too large, compute shrinking size
1654     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1655     ergo_verbose4(ErgoHeapSizing,
1656                   "attempt heap shrinking",
1657                   ergo_format_reason("capacity higher than "
1658                                      "max desired capacity after Full GC")
1659                   ergo_format_byte("capacity")
1660                   ergo_format_byte("occupancy")
1661                   ergo_format_byte_perc("max desired capacity"),
1662                   capacity_after_gc, used_after_gc,
1663                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1664     shrink(shrink_bytes);
1665   }
1666 }
1667 
1668 
1669 HeapWord*
1670 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1671                                            bool* succeeded) {
1672   assert_at_safepoint(true /* should_be_vm_thread */);
1673 
1674   *succeeded = true;
1675   // Let's attempt the allocation first.
1676   HeapWord* result =
1677     attempt_allocation_at_safepoint(word_size,
1678                                  false /* expect_null_mutator_alloc_region */);
1679   if (result != NULL) {
1680     assert(*succeeded, "sanity");
1681     return result;
1682   }
1683 
1684   // In a G1 heap, we're supposed to keep allocation from failing by
1685   // incremental pauses.  Therefore, at least for now, we'll favor
1686   // expansion over collection.  (This might change in the future if we can
1687   // do something smarter than full collection to satisfy a failed alloc.)
1688   result = expand_and_allocate(word_size);
1689   if (result != NULL) {
1690     assert(*succeeded, "sanity");
1691     return result;
1692   }
1693 
1694   // Expansion didn't work, we'll try to do a Full GC.
1695   bool gc_succeeded = do_collection(false, /* explicit_gc */
1696                                     false, /* clear_all_soft_refs */
1697                                     word_size);
1698   if (!gc_succeeded) {
1699     *succeeded = false;
1700     return NULL;
1701   }
1702 
1703   // Retry the allocation
1704   result = attempt_allocation_at_safepoint(word_size,
1705                                   true /* expect_null_mutator_alloc_region */);
1706   if (result != NULL) {
1707     assert(*succeeded, "sanity");
1708     return result;
1709   }
1710 
1711   // Then, try a Full GC that will collect all soft references.
1712   gc_succeeded = do_collection(false, /* explicit_gc */
1713                                true,  /* clear_all_soft_refs */
1714                                word_size);
1715   if (!gc_succeeded) {
1716     *succeeded = false;
1717     return NULL;
1718   }
1719 
1720   // Retry the allocation once more
1721   result = attempt_allocation_at_safepoint(word_size,
1722                                   true /* expect_null_mutator_alloc_region */);
1723   if (result != NULL) {
1724     assert(*succeeded, "sanity");
1725     return result;
1726   }
1727 
1728   assert(!collector_policy()->should_clear_all_soft_refs(),
1729          "Flag should have been handled and cleared prior to this point");
1730 
1731   // What else?  We might try synchronous finalization later.  If the total
1732   // space available is large enough for the allocation, then a more
1733   // complete compaction phase than we've tried so far might be
1734   // appropriate.
1735   assert(*succeeded, "sanity");
1736   return NULL;
1737 }
1738 
1739 // Attempting to expand the heap sufficiently
1740 // to support an allocation of the given "word_size".  If
1741 // successful, perform the allocation and return the address of the
1742 // allocated block, or else "NULL".
1743 
1744 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1745   assert_at_safepoint(true /* should_be_vm_thread */);
1746 
1747   verify_region_sets_optional();
1748 
1749   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1750   ergo_verbose1(ErgoHeapSizing,
1751                 "attempt heap expansion",
1752                 ergo_format_reason("allocation request failed")
1753                 ergo_format_byte("allocation request"),
1754                 word_size * HeapWordSize);
1755   if (expand(expand_bytes)) {
1756     _hrs.verify_optional();
1757     verify_region_sets_optional();
1758     return attempt_allocation_at_safepoint(word_size,
1759                                  false /* expect_null_mutator_alloc_region */);
1760   }
1761   return NULL;
1762 }
1763 
1764 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1765                                              HeapWord* new_end) {
1766   assert(old_end != new_end, "don't call this otherwise");
1767   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1768 
1769   // Update the committed mem region.
1770   _g1_committed.set_end(new_end);
1771   // Tell the card table about the update.
1772   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1773   // Tell the BOT about the update.
1774   _bot_shared->resize(_g1_committed.word_size());
1775   // Tell the hot card cache about the update
1776   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1777 }
1778 
1779 bool G1CollectedHeap::expand(size_t expand_bytes) {
1780   size_t old_mem_size = _g1_storage.committed_size();
1781   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1782   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1783                                        HeapRegion::GrainBytes);
1784   ergo_verbose2(ErgoHeapSizing,
1785                 "expand the heap",
1786                 ergo_format_byte("requested expansion amount")
1787                 ergo_format_byte("attempted expansion amount"),
1788                 expand_bytes, aligned_expand_bytes);
1789 
1790   // First commit the memory.
1791   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1792   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1793   if (successful) {
1794     // Then propagate this update to the necessary data structures.
1795     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1796     update_committed_space(old_end, new_end);
1797 
1798     FreeRegionList expansion_list("Local Expansion List");
1799     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1800     assert(mr.start() == old_end, "post-condition");
1801     // mr might be a smaller region than what was requested if
1802     // expand_by() was unable to allocate the HeapRegion instances
1803     assert(mr.end() <= new_end, "post-condition");
1804 
1805     size_t actual_expand_bytes = mr.byte_size();
1806     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1807     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1808            "post-condition");
1809     if (actual_expand_bytes < aligned_expand_bytes) {
1810       // We could not expand _hrs to the desired size. In this case we
1811       // need to shrink the committed space accordingly.
1812       assert(mr.end() < new_end, "invariant");
1813 
1814       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1815       // First uncommit the memory.
1816       _g1_storage.shrink_by(diff_bytes);
1817       // Then propagate this update to the necessary data structures.
1818       update_committed_space(new_end, mr.end());
1819     }
1820     _free_list.add_as_tail(&expansion_list);
1821 
1822     if (_hr_printer.is_active()) {
1823       HeapWord* curr = mr.start();
1824       while (curr < mr.end()) {
1825         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1826         _hr_printer.commit(curr, curr_end);
1827         curr = curr_end;
1828       }
1829       assert(curr == mr.end(), "post-condition");
1830     }
1831     g1_policy()->record_new_heap_size(n_regions());
1832   } else {
1833     ergo_verbose0(ErgoHeapSizing,
1834                   "did not expand the heap",
1835                   ergo_format_reason("heap expansion operation failed"));
1836     // The expansion of the virtual storage space was unsuccessful.
1837     // Let's see if it was because we ran out of swap.
1838     if (G1ExitOnExpansionFailure &&
1839         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1840       // We had head room...
1841       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1842     }
1843   }
1844   return successful;
1845 }
1846 
1847 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1848   size_t old_mem_size = _g1_storage.committed_size();
1849   size_t aligned_shrink_bytes =
1850     ReservedSpace::page_align_size_down(shrink_bytes);
1851   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1852                                          HeapRegion::GrainBytes);
1853   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1854 
1855   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1856   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1857   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1858 
1859   ergo_verbose3(ErgoHeapSizing,
1860                 "shrink the heap",
1861                 ergo_format_byte("requested shrinking amount")
1862                 ergo_format_byte("aligned shrinking amount")
1863                 ergo_format_byte("attempted shrinking amount"),
1864                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1865   if (num_regions_removed > 0) {
1866     _g1_storage.shrink_by(shrunk_bytes);
1867     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1868 
1869     if (_hr_printer.is_active()) {
1870       HeapWord* curr = old_end;
1871       while (curr > new_end) {
1872         HeapWord* curr_end = curr;
1873         curr -= HeapRegion::GrainWords;
1874         _hr_printer.uncommit(curr, curr_end);
1875       }
1876     }
1877 
1878     _expansion_regions += num_regions_removed;
1879     update_committed_space(old_end, new_end);
1880     HeapRegionRemSet::shrink_heap(n_regions());
1881     g1_policy()->record_new_heap_size(n_regions());
1882   } else {
1883     ergo_verbose0(ErgoHeapSizing,
1884                   "did not shrink the heap",
1885                   ergo_format_reason("heap shrinking operation failed"));
1886   }
1887 }
1888 
1889 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1890   verify_region_sets_optional();
1891 
1892   // We should only reach here at the end of a Full GC which means we
1893   // should not not be holding to any GC alloc regions. The method
1894   // below will make sure of that and do any remaining clean up.
1895   abandon_gc_alloc_regions();
1896 
1897   // Instead of tearing down / rebuilding the free lists here, we
1898   // could instead use the remove_all_pending() method on free_list to
1899   // remove only the ones that we need to remove.
1900   tear_down_region_sets(true /* free_list_only */);
1901   shrink_helper(shrink_bytes);
1902   rebuild_region_sets(true /* free_list_only */);
1903 
1904   _hrs.verify_optional();
1905   verify_region_sets_optional();
1906 }
1907 
1908 // Public methods.
1909 
1910 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1911 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1912 #endif // _MSC_VER
1913 
1914 
1915 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1916   SharedHeap(policy_),
1917   _g1_policy(policy_),
1918   _dirty_card_queue_set(false),
1919   _into_cset_dirty_card_queue_set(false),
1920   _is_alive_closure_cm(this),
1921   _is_alive_closure_stw(this),
1922   _ref_processor_cm(NULL),
1923   _ref_processor_stw(NULL),
1924   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1925   _bot_shared(NULL),
1926   _evac_failure_scan_stack(NULL),
1927   _mark_in_progress(false),
1928   _cg1r(NULL), _summary_bytes_used(0),
1929   _g1mm(NULL),
1930   _refine_cte_cl(NULL),
1931   _full_collection(false),
1932   _free_list("Master Free List"),
1933   _secondary_free_list("Secondary Free List"),
1934   _old_set("Old Set"),
1935   _humongous_set("Master Humongous Set"),
1936   _free_regions_coming(false),
1937   _young_list(new YoungList(this)),
1938   _gc_time_stamp(0),
1939   _retained_old_gc_alloc_region(NULL),
1940   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1941   _old_plab_stats(OldPLABSize, PLABWeight),
1942   _expand_heap_after_alloc_failure(true),
1943   _surviving_young_words(NULL),
1944   _old_marking_cycles_started(0),
1945   _old_marking_cycles_completed(0),
1946   _concurrent_cycle_started(false),
1947   _in_cset_fast_test(NULL),
1948   _in_cset_fast_test_base(NULL),
1949   _dirty_cards_region_list(NULL),
1950   _worker_cset_start_region(NULL),
1951   _worker_cset_start_region_time_stamp(NULL),
1952   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1953   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1954   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1955   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1956 
1957   _g1h = this;
1958   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1959     vm_exit_during_initialization("Failed necessary allocation.");
1960   }
1961 
1962   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1963 
1964   int n_queues = MAX2((int)ParallelGCThreads, 1);
1965   _task_queues = new RefToScanQueueSet(n_queues);
1966 
1967   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1968   assert(n_rem_sets > 0, "Invariant.");
1969 
1970   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1971   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1972   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1973 
1974   for (int i = 0; i < n_queues; i++) {
1975     RefToScanQueue* q = new RefToScanQueue();
1976     q->initialize();
1977     _task_queues->register_queue(i, q);
1978     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1979   }
1980   clear_cset_start_regions();
1981 
1982   // Initialize the G1EvacuationFailureALot counters and flags.
1983   NOT_PRODUCT(reset_evacuation_should_fail();)
1984 
1985   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1986 }
1987 
1988 jint G1CollectedHeap::initialize() {
1989   CollectedHeap::pre_initialize();
1990   os::enable_vtime();
1991 
1992   G1Log::init();
1993 
1994   // Necessary to satisfy locking discipline assertions.
1995 
1996   MutexLocker x(Heap_lock);
1997 
1998   // We have to initialize the printer before committing the heap, as
1999   // it will be used then.
2000   _hr_printer.set_active(G1PrintHeapRegions);
2001 
2002   // While there are no constraints in the GC code that HeapWordSize
2003   // be any particular value, there are multiple other areas in the
2004   // system which believe this to be true (e.g. oop->object_size in some
2005   // cases incorrectly returns the size in wordSize units rather than
2006   // HeapWordSize).
2007   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2008 
2009   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2010   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2011 
2012   // Ensure that the sizes are properly aligned.
2013   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2014   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2015 
2016   _cg1r = new ConcurrentG1Refine(this);
2017 
2018   // Reserve the maximum.
2019 
2020   // When compressed oops are enabled, the preferred heap base
2021   // is calculated by subtracting the requested size from the
2022   // 32Gb boundary and using the result as the base address for
2023   // heap reservation. If the requested size is not aligned to
2024   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2025   // into the ReservedHeapSpace constructor) then the actual
2026   // base of the reserved heap may end up differing from the
2027   // address that was requested (i.e. the preferred heap base).
2028   // If this happens then we could end up using a non-optimal
2029   // compressed oops mode.
2030 
2031   // Since max_byte_size is aligned to the size of a heap region (checked
2032   // above).
2033   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2034 
2035   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2036                                                  HeapRegion::GrainBytes);
2037 
2038   // It is important to do this in a way such that concurrent readers can't
2039   // temporarily think something is in the heap.  (I've actually seen this
2040   // happen in asserts: DLD.)
2041   _reserved.set_word_size(0);
2042   _reserved.set_start((HeapWord*)heap_rs.base());
2043   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2044 
2045   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2046 
2047   // Create the gen rem set (and barrier set) for the entire reserved region.
2048   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2049   set_barrier_set(rem_set()->bs());
2050   if (barrier_set()->is_a(BarrierSet::ModRef)) {
2051     _mr_bs = (ModRefBarrierSet*)_barrier_set;
2052   } else {
2053     vm_exit_during_initialization("G1 requires a mod ref bs.");
2054     return JNI_ENOMEM;
2055   }
2056 
2057   // Also create a G1 rem set.
2058   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2059     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2060   } else {
2061     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2062     return JNI_ENOMEM;
2063   }
2064 
2065   // Carve out the G1 part of the heap.
2066 
2067   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2068   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2069                            g1_rs.size()/HeapWordSize);
2070 
2071   _g1_storage.initialize(g1_rs, 0);
2072   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2073   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2074                   (HeapWord*) _g1_reserved.end(),
2075                   _expansion_regions);
2076 
2077   // Do later initialization work for concurrent refinement.
2078   _cg1r->init();
2079 
2080   // 6843694 - ensure that the maximum region index can fit
2081   // in the remembered set structures.
2082   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2083   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2084 
2085   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2086   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2087   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2088             "too many cards per region");
2089 
2090   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2091 
2092   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2093                                              heap_word_size(init_byte_size));
2094 
2095   _g1h = this;
2096 
2097   _in_cset_fast_test_length = max_regions();
2098   _in_cset_fast_test_base =
2099                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2100 
2101   // We're biasing _in_cset_fast_test to avoid subtracting the
2102   // beginning of the heap every time we want to index; basically
2103   // it's the same with what we do with the card table.
2104   _in_cset_fast_test = _in_cset_fast_test_base -
2105                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2106 
2107   // Clear the _cset_fast_test bitmap in anticipation of adding
2108   // regions to the incremental collection set for the first
2109   // evacuation pause.
2110   clear_cset_fast_test();
2111 
2112   // Create the ConcurrentMark data structure and thread.
2113   // (Must do this late, so that "max_regions" is defined.)
2114   _cm = new ConcurrentMark(this, heap_rs);
2115   if (_cm == NULL || !_cm->completed_initialization()) {
2116     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2117     return JNI_ENOMEM;
2118   }
2119   _cmThread = _cm->cmThread();
2120 
2121   // Initialize the from_card cache structure of HeapRegionRemSet.
2122   HeapRegionRemSet::init_heap(max_regions());
2123 
2124   // Now expand into the initial heap size.
2125   if (!expand(init_byte_size)) {
2126     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2127     return JNI_ENOMEM;
2128   }
2129 
2130   // Perform any initialization actions delegated to the policy.
2131   g1_policy()->init();
2132 
2133   _refine_cte_cl =
2134     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2135                                     g1_rem_set(),
2136                                     concurrent_g1_refine());
2137   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2138 
2139   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2140                                                SATB_Q_FL_lock,
2141                                                G1SATBProcessCompletedThreshold,
2142                                                Shared_SATB_Q_lock);
2143 
2144   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2145                                                 DirtyCardQ_FL_lock,
2146                                                 concurrent_g1_refine()->yellow_zone(),
2147                                                 concurrent_g1_refine()->red_zone(),
2148                                                 Shared_DirtyCardQ_lock);
2149 
2150   if (G1DeferredRSUpdate) {
2151     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2152                                       DirtyCardQ_FL_lock,
2153                                       -1, // never trigger processing
2154                                       -1, // no limit on length
2155                                       Shared_DirtyCardQ_lock,
2156                                       &JavaThread::dirty_card_queue_set());
2157   }
2158 
2159   // Initialize the card queue set used to hold cards containing
2160   // references into the collection set.
2161   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2162                                              DirtyCardQ_FL_lock,
2163                                              -1, // never trigger processing
2164                                              -1, // no limit on length
2165                                              Shared_DirtyCardQ_lock,
2166                                              &JavaThread::dirty_card_queue_set());
2167 
2168   // In case we're keeping closure specialization stats, initialize those
2169   // counts and that mechanism.
2170   SpecializationStats::clear();
2171 
2172   // Here we allocate the dummy full region that is required by the
2173   // G1AllocRegion class. If we don't pass an address in the reserved
2174   // space here, lots of asserts fire.
2175 
2176   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2177                                              _g1_reserved.start());
2178   // We'll re-use the same region whether the alloc region will
2179   // require BOT updates or not and, if it doesn't, then a non-young
2180   // region will complain that it cannot support allocations without
2181   // BOT updates. So we'll tag the dummy region as young to avoid that.
2182   dummy_region->set_young();
2183   // Make sure it's full.
2184   dummy_region->set_top(dummy_region->end());
2185   G1AllocRegion::setup(this, dummy_region);
2186 
2187   init_mutator_alloc_region();
2188 
2189   // Do create of the monitoring and management support so that
2190   // values in the heap have been properly initialized.
2191   _g1mm = new G1MonitoringSupport(this);
2192 
2193   return JNI_OK;
2194 }
2195 
2196 void G1CollectedHeap::ref_processing_init() {
2197   // Reference processing in G1 currently works as follows:
2198   //
2199   // * There are two reference processor instances. One is
2200   //   used to record and process discovered references
2201   //   during concurrent marking; the other is used to
2202   //   record and process references during STW pauses
2203   //   (both full and incremental).
2204   // * Both ref processors need to 'span' the entire heap as
2205   //   the regions in the collection set may be dotted around.
2206   //
2207   // * For the concurrent marking ref processor:
2208   //   * Reference discovery is enabled at initial marking.
2209   //   * Reference discovery is disabled and the discovered
2210   //     references processed etc during remarking.
2211   //   * Reference discovery is MT (see below).
2212   //   * Reference discovery requires a barrier (see below).
2213   //   * Reference processing may or may not be MT
2214   //     (depending on the value of ParallelRefProcEnabled
2215   //     and ParallelGCThreads).
2216   //   * A full GC disables reference discovery by the CM
2217   //     ref processor and abandons any entries on it's
2218   //     discovered lists.
2219   //
2220   // * For the STW processor:
2221   //   * Non MT discovery is enabled at the start of a full GC.
2222   //   * Processing and enqueueing during a full GC is non-MT.
2223   //   * During a full GC, references are processed after marking.
2224   //
2225   //   * Discovery (may or may not be MT) is enabled at the start
2226   //     of an incremental evacuation pause.
2227   //   * References are processed near the end of a STW evacuation pause.
2228   //   * For both types of GC:
2229   //     * Discovery is atomic - i.e. not concurrent.
2230   //     * Reference discovery will not need a barrier.
2231 
2232   SharedHeap::ref_processing_init();
2233   MemRegion mr = reserved_region();
2234 
2235   // Concurrent Mark ref processor
2236   _ref_processor_cm =
2237     new ReferenceProcessor(mr,    // span
2238                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2239                                 // mt processing
2240                            (int) ParallelGCThreads,
2241                                 // degree of mt processing
2242                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2243                                 // mt discovery
2244                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2245                                 // degree of mt discovery
2246                            false,
2247                                 // Reference discovery is not atomic
2248                            &_is_alive_closure_cm,
2249                                 // is alive closure
2250                                 // (for efficiency/performance)
2251                            true);
2252                                 // Setting next fields of discovered
2253                                 // lists requires a barrier.
2254 
2255   // STW ref processor
2256   _ref_processor_stw =
2257     new ReferenceProcessor(mr,    // span
2258                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2259                                 // mt processing
2260                            MAX2((int)ParallelGCThreads, 1),
2261                                 // degree of mt processing
2262                            (ParallelGCThreads > 1),
2263                                 // mt discovery
2264                            MAX2((int)ParallelGCThreads, 1),
2265                                 // degree of mt discovery
2266                            true,
2267                                 // Reference discovery is atomic
2268                            &_is_alive_closure_stw,
2269                                 // is alive closure
2270                                 // (for efficiency/performance)
2271                            false);
2272                                 // Setting next fields of discovered
2273                                 // lists requires a barrier.
2274 }
2275 
2276 size_t G1CollectedHeap::capacity() const {
2277   return _g1_committed.byte_size();
2278 }
2279 
2280 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2281   assert(!hr->continuesHumongous(), "pre-condition");
2282   hr->reset_gc_time_stamp();
2283   if (hr->startsHumongous()) {
2284     uint first_index = hr->hrs_index() + 1;
2285     uint last_index = hr->last_hc_index();
2286     for (uint i = first_index; i < last_index; i += 1) {
2287       HeapRegion* chr = region_at(i);
2288       assert(chr->continuesHumongous(), "sanity");
2289       chr->reset_gc_time_stamp();
2290     }
2291   }
2292 }
2293 
2294 #ifndef PRODUCT
2295 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2296 private:
2297   unsigned _gc_time_stamp;
2298   bool _failures;
2299 
2300 public:
2301   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2302     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2303 
2304   virtual bool doHeapRegion(HeapRegion* hr) {
2305     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2306     if (_gc_time_stamp != region_gc_time_stamp) {
2307       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2308                              "expected %d", HR_FORMAT_PARAMS(hr),
2309                              region_gc_time_stamp, _gc_time_stamp);
2310       _failures = true;
2311     }
2312     return false;
2313   }
2314 
2315   bool failures() { return _failures; }
2316 };
2317 
2318 void G1CollectedHeap::check_gc_time_stamps() {
2319   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2320   heap_region_iterate(&cl);
2321   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2322 }
2323 #endif // PRODUCT
2324 
2325 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2326                                                  DirtyCardQueue* into_cset_dcq,
2327                                                  bool concurrent,
2328                                                  int worker_i) {
2329   // Clean cards in the hot card cache
2330   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2331   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2332 
2333   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2334   int n_completed_buffers = 0;
2335   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2336     n_completed_buffers++;
2337   }
2338   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2339   dcqs.clear_n_completed_buffers();
2340   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2341 }
2342 
2343 
2344 // Computes the sum of the storage used by the various regions.
2345 
2346 size_t G1CollectedHeap::used() const {
2347   assert(Heap_lock->owner() != NULL,
2348          "Should be owned on this thread's behalf.");
2349   size_t result = _summary_bytes_used;
2350   // Read only once in case it is set to NULL concurrently
2351   HeapRegion* hr = _mutator_alloc_region.get();
2352   if (hr != NULL)
2353     result += hr->used();
2354   return result;
2355 }
2356 
2357 size_t G1CollectedHeap::used_unlocked() const {
2358   size_t result = _summary_bytes_used;
2359   return result;
2360 }
2361 
2362 class SumUsedClosure: public HeapRegionClosure {
2363   size_t _used;
2364 public:
2365   SumUsedClosure() : _used(0) {}
2366   bool doHeapRegion(HeapRegion* r) {
2367     if (!r->continuesHumongous()) {
2368       _used += r->used();
2369     }
2370     return false;
2371   }
2372   size_t result() { return _used; }
2373 };
2374 
2375 size_t G1CollectedHeap::recalculate_used() const {
2376   SumUsedClosure blk;
2377   heap_region_iterate(&blk);
2378   return blk.result();
2379 }
2380 
2381 size_t G1CollectedHeap::unsafe_max_alloc() {
2382   if (free_regions() > 0) return HeapRegion::GrainBytes;
2383   // otherwise, is there space in the current allocation region?
2384 
2385   // We need to store the current allocation region in a local variable
2386   // here. The problem is that this method doesn't take any locks and
2387   // there may be other threads which overwrite the current allocation
2388   // region field. attempt_allocation(), for example, sets it to NULL
2389   // and this can happen *after* the NULL check here but before the call
2390   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2391   // to be a problem in the optimized build, since the two loads of the
2392   // current allocation region field are optimized away.
2393   HeapRegion* hr = _mutator_alloc_region.get();
2394   if (hr == NULL) {
2395     return 0;
2396   }
2397   return hr->free();
2398 }
2399 
2400 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2401   switch (cause) {
2402     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2403     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2404     case GCCause::_g1_humongous_allocation: return true;
2405     default:                                return false;
2406   }
2407 }
2408 
2409 #ifndef PRODUCT
2410 void G1CollectedHeap::allocate_dummy_regions() {
2411   // Let's fill up most of the region
2412   size_t word_size = HeapRegion::GrainWords - 1024;
2413   // And as a result the region we'll allocate will be humongous.
2414   guarantee(isHumongous(word_size), "sanity");
2415 
2416   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2417     // Let's use the existing mechanism for the allocation
2418     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2419     if (dummy_obj != NULL) {
2420       MemRegion mr(dummy_obj, word_size);
2421       CollectedHeap::fill_with_object(mr);
2422     } else {
2423       // If we can't allocate once, we probably cannot allocate
2424       // again. Let's get out of the loop.
2425       break;
2426     }
2427   }
2428 }
2429 #endif // !PRODUCT
2430 
2431 void G1CollectedHeap::increment_old_marking_cycles_started() {
2432   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2433     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2434     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2435     _old_marking_cycles_started, _old_marking_cycles_completed));
2436 
2437   _old_marking_cycles_started++;
2438 }
2439 
2440 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2441   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2442 
2443   // We assume that if concurrent == true, then the caller is a
2444   // concurrent thread that was joined the Suspendible Thread
2445   // Set. If there's ever a cheap way to check this, we should add an
2446   // assert here.
2447 
2448   // Given that this method is called at the end of a Full GC or of a
2449   // concurrent cycle, and those can be nested (i.e., a Full GC can
2450   // interrupt a concurrent cycle), the number of full collections
2451   // completed should be either one (in the case where there was no
2452   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2453   // behind the number of full collections started.
2454 
2455   // This is the case for the inner caller, i.e. a Full GC.
2456   assert(concurrent ||
2457          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2458          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2459          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2460                  "is inconsistent with _old_marking_cycles_completed = %u",
2461                  _old_marking_cycles_started, _old_marking_cycles_completed));
2462 
2463   // This is the case for the outer caller, i.e. the concurrent cycle.
2464   assert(!concurrent ||
2465          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2466          err_msg("for outer caller (concurrent cycle): "
2467                  "_old_marking_cycles_started = %u "
2468                  "is inconsistent with _old_marking_cycles_completed = %u",
2469                  _old_marking_cycles_started, _old_marking_cycles_completed));
2470 
2471   _old_marking_cycles_completed += 1;
2472 
2473   // We need to clear the "in_progress" flag in the CM thread before
2474   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2475   // is set) so that if a waiter requests another System.gc() it doesn't
2476   // incorrectly see that a marking cycle is still in progress.
2477   if (concurrent) {
2478     _cmThread->clear_in_progress();
2479   }
2480 
2481   // This notify_all() will ensure that a thread that called
2482   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2483   // and it's waiting for a full GC to finish will be woken up. It is
2484   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2485   FullGCCount_lock->notify_all();
2486 }
2487 
2488 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2489   _concurrent_cycle_started = true;
2490   _gc_timer_cm->register_gc_start(start_time);
2491 
2492   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2493   trace_heap_before_gc(_gc_tracer_cm);
2494 }
2495 
2496 void G1CollectedHeap::register_concurrent_cycle_end() {
2497   if (_concurrent_cycle_started) {
2498     _gc_timer_cm->register_gc_end(os::elapsed_counter());
2499 
2500     if (_cm->has_aborted()) {
2501       _gc_tracer_cm->report_concurrent_mode_failure();
2502     }
2503     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2504 
2505     _concurrent_cycle_started = false;
2506   }
2507 }
2508 
2509 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2510   if (_concurrent_cycle_started) {
2511     trace_heap_after_gc(_gc_tracer_cm);
2512   }
2513 }
2514 
2515 G1YCType G1CollectedHeap::yc_type() {
2516   bool is_young = g1_policy()->gcs_are_young();
2517   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2518   bool is_during_mark = mark_in_progress();
2519 
2520   if (is_initial_mark) {
2521     return InitialMark;
2522   } else if (is_during_mark) {
2523     return DuringMark;
2524   } else if (is_young) {
2525     return Normal;
2526   } else {
2527     return Mixed;
2528   }
2529 }
2530 
2531 void G1CollectedHeap::collect(GCCause::Cause cause) {
2532   assert_heap_not_locked();
2533 
2534   unsigned int gc_count_before;
2535   unsigned int old_marking_count_before;
2536   bool retry_gc;
2537 
2538   do {
2539     retry_gc = false;
2540 
2541     {
2542       MutexLocker ml(Heap_lock);
2543 
2544       // Read the GC count while holding the Heap_lock
2545       gc_count_before = total_collections();
2546       old_marking_count_before = _old_marking_cycles_started;
2547     }
2548 
2549     if (should_do_concurrent_full_gc(cause)) {
2550       // Schedule an initial-mark evacuation pause that will start a
2551       // concurrent cycle. We're setting word_size to 0 which means that
2552       // we are not requesting a post-GC allocation.
2553       VM_G1IncCollectionPause op(gc_count_before,
2554                                  0,     /* word_size */
2555                                  true,  /* should_initiate_conc_mark */
2556                                  g1_policy()->max_pause_time_ms(),
2557                                  cause);
2558 
2559       VMThread::execute(&op);
2560       if (!op.pause_succeeded()) {
2561         if (old_marking_count_before == _old_marking_cycles_started) {
2562           retry_gc = op.should_retry_gc();
2563         } else {
2564           // A Full GC happened while we were trying to schedule the
2565           // initial-mark GC. No point in starting a new cycle given
2566           // that the whole heap was collected anyway.
2567         }
2568 
2569         if (retry_gc) {
2570           if (GC_locker::is_active_and_needs_gc()) {
2571             GC_locker::stall_until_clear();
2572           }
2573         }
2574       }
2575     } else {
2576       if (cause == GCCause::_gc_locker
2577           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2578 
2579         // Schedule a standard evacuation pause. We're setting word_size
2580         // to 0 which means that we are not requesting a post-GC allocation.
2581         VM_G1IncCollectionPause op(gc_count_before,
2582                                    0,     /* word_size */
2583                                    false, /* should_initiate_conc_mark */
2584                                    g1_policy()->max_pause_time_ms(),
2585                                    cause);
2586         VMThread::execute(&op);
2587       } else {
2588         // Schedule a Full GC.
2589         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2590         VMThread::execute(&op);
2591       }
2592     }
2593   } while (retry_gc);
2594 }
2595 
2596 bool G1CollectedHeap::is_in(const void* p) const {
2597   if (_g1_committed.contains(p)) {
2598     // Given that we know that p is in the committed space,
2599     // heap_region_containing_raw() should successfully
2600     // return the containing region.
2601     HeapRegion* hr = heap_region_containing_raw(p);
2602     return hr->is_in(p);
2603   } else {
2604     return false;
2605   }
2606 }
2607 
2608 // Iteration functions.
2609 
2610 // Iterates an OopClosure over all ref-containing fields of objects
2611 // within a HeapRegion.
2612 
2613 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2614   MemRegion _mr;
2615   ExtendedOopClosure* _cl;
2616 public:
2617   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2618     : _mr(mr), _cl(cl) {}
2619   bool doHeapRegion(HeapRegion* r) {
2620     if (!r->continuesHumongous()) {
2621       r->oop_iterate(_cl);
2622     }
2623     return false;
2624   }
2625 };
2626 
2627 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2628   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2629   heap_region_iterate(&blk);
2630 }
2631 
2632 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2633   IterateOopClosureRegionClosure blk(mr, cl);
2634   heap_region_iterate(&blk);
2635 }
2636 
2637 // Iterates an ObjectClosure over all objects within a HeapRegion.
2638 
2639 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2640   ObjectClosure* _cl;
2641 public:
2642   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2643   bool doHeapRegion(HeapRegion* r) {
2644     if (! r->continuesHumongous()) {
2645       r->object_iterate(_cl);
2646     }
2647     return false;
2648   }
2649 };
2650 
2651 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2652   IterateObjectClosureRegionClosure blk(cl);
2653   heap_region_iterate(&blk);
2654 }
2655 
2656 // Calls a SpaceClosure on a HeapRegion.
2657 
2658 class SpaceClosureRegionClosure: public HeapRegionClosure {
2659   SpaceClosure* _cl;
2660 public:
2661   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2662   bool doHeapRegion(HeapRegion* r) {
2663     _cl->do_space(r);
2664     return false;
2665   }
2666 };
2667 
2668 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2669   SpaceClosureRegionClosure blk(cl);
2670   heap_region_iterate(&blk);
2671 }
2672 
2673 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2674   _hrs.iterate(cl);
2675 }
2676 
2677 void
2678 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2679                                                  uint worker_id,
2680                                                  uint no_of_par_workers,
2681                                                  jint claim_value) {
2682   const uint regions = n_regions();
2683   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2684                              no_of_par_workers :
2685                              1);
2686   assert(UseDynamicNumberOfGCThreads ||
2687          no_of_par_workers == workers()->total_workers(),
2688          "Non dynamic should use fixed number of workers");
2689   // try to spread out the starting points of the workers
2690   const HeapRegion* start_hr =
2691                         start_region_for_worker(worker_id, no_of_par_workers);
2692   const uint start_index = start_hr->hrs_index();
2693 
2694   // each worker will actually look at all regions
2695   for (uint count = 0; count < regions; ++count) {
2696     const uint index = (start_index + count) % regions;
2697     assert(0 <= index && index < regions, "sanity");
2698     HeapRegion* r = region_at(index);
2699     // we'll ignore "continues humongous" regions (we'll process them
2700     // when we come across their corresponding "start humongous"
2701     // region) and regions already claimed
2702     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2703       continue;
2704     }
2705     // OK, try to claim it
2706     if (r->claimHeapRegion(claim_value)) {
2707       // success!
2708       assert(!r->continuesHumongous(), "sanity");
2709       if (r->startsHumongous()) {
2710         // If the region is "starts humongous" we'll iterate over its
2711         // "continues humongous" first; in fact we'll do them
2712         // first. The order is important. In on case, calling the
2713         // closure on the "starts humongous" region might de-allocate
2714         // and clear all its "continues humongous" regions and, as a
2715         // result, we might end up processing them twice. So, we'll do
2716         // them first (notice: most closures will ignore them anyway) and
2717         // then we'll do the "starts humongous" region.
2718         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2719           HeapRegion* chr = region_at(ch_index);
2720 
2721           // if the region has already been claimed or it's not
2722           // "continues humongous" we're done
2723           if (chr->claim_value() == claim_value ||
2724               !chr->continuesHumongous()) {
2725             break;
2726           }
2727 
2728           // No one should have claimed it directly. We can given
2729           // that we claimed its "starts humongous" region.
2730           assert(chr->claim_value() != claim_value, "sanity");
2731           assert(chr->humongous_start_region() == r, "sanity");
2732 
2733           if (chr->claimHeapRegion(claim_value)) {
2734             // we should always be able to claim it; no one else should
2735             // be trying to claim this region
2736 
2737             bool res2 = cl->doHeapRegion(chr);
2738             assert(!res2, "Should not abort");
2739 
2740             // Right now, this holds (i.e., no closure that actually
2741             // does something with "continues humongous" regions
2742             // clears them). We might have to weaken it in the future,
2743             // but let's leave these two asserts here for extra safety.
2744             assert(chr->continuesHumongous(), "should still be the case");
2745             assert(chr->humongous_start_region() == r, "sanity");
2746           } else {
2747             guarantee(false, "we should not reach here");
2748           }
2749         }
2750       }
2751 
2752       assert(!r->continuesHumongous(), "sanity");
2753       bool res = cl->doHeapRegion(r);
2754       assert(!res, "Should not abort");
2755     }
2756   }
2757 }
2758 
2759 class ResetClaimValuesClosure: public HeapRegionClosure {
2760 public:
2761   bool doHeapRegion(HeapRegion* r) {
2762     r->set_claim_value(HeapRegion::InitialClaimValue);
2763     return false;
2764   }
2765 };
2766 
2767 void G1CollectedHeap::reset_heap_region_claim_values() {
2768   ResetClaimValuesClosure blk;
2769   heap_region_iterate(&blk);
2770 }
2771 
2772 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2773   ResetClaimValuesClosure blk;
2774   collection_set_iterate(&blk);
2775 }
2776 
2777 #ifdef ASSERT
2778 // This checks whether all regions in the heap have the correct claim
2779 // value. I also piggy-backed on this a check to ensure that the
2780 // humongous_start_region() information on "continues humongous"
2781 // regions is correct.
2782 
2783 class CheckClaimValuesClosure : public HeapRegionClosure {
2784 private:
2785   jint _claim_value;
2786   uint _failures;
2787   HeapRegion* _sh_region;
2788 
2789 public:
2790   CheckClaimValuesClosure(jint claim_value) :
2791     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2792   bool doHeapRegion(HeapRegion* r) {
2793     if (r->claim_value() != _claim_value) {
2794       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2795                              "claim value = %d, should be %d",
2796                              HR_FORMAT_PARAMS(r),
2797                              r->claim_value(), _claim_value);
2798       ++_failures;
2799     }
2800     if (!r->isHumongous()) {
2801       _sh_region = NULL;
2802     } else if (r->startsHumongous()) {
2803       _sh_region = r;
2804     } else if (r->continuesHumongous()) {
2805       if (r->humongous_start_region() != _sh_region) {
2806         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2807                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2808                                HR_FORMAT_PARAMS(r),
2809                                r->humongous_start_region(),
2810                                _sh_region);
2811         ++_failures;
2812       }
2813     }
2814     return false;
2815   }
2816   uint failures() { return _failures; }
2817 };
2818 
2819 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2820   CheckClaimValuesClosure cl(claim_value);
2821   heap_region_iterate(&cl);
2822   return cl.failures() == 0;
2823 }
2824 
2825 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2826 private:
2827   jint _claim_value;
2828   uint _failures;
2829 
2830 public:
2831   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2832     _claim_value(claim_value), _failures(0) { }
2833 
2834   uint failures() { return _failures; }
2835 
2836   bool doHeapRegion(HeapRegion* hr) {
2837     assert(hr->in_collection_set(), "how?");
2838     assert(!hr->isHumongous(), "H-region in CSet");
2839     if (hr->claim_value() != _claim_value) {
2840       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2841                              "claim value = %d, should be %d",
2842                              HR_FORMAT_PARAMS(hr),
2843                              hr->claim_value(), _claim_value);
2844       _failures += 1;
2845     }
2846     return false;
2847   }
2848 };
2849 
2850 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2851   CheckClaimValuesInCSetHRClosure cl(claim_value);
2852   collection_set_iterate(&cl);
2853   return cl.failures() == 0;
2854 }
2855 #endif // ASSERT
2856 
2857 // Clear the cached CSet starting regions and (more importantly)
2858 // the time stamps. Called when we reset the GC time stamp.
2859 void G1CollectedHeap::clear_cset_start_regions() {
2860   assert(_worker_cset_start_region != NULL, "sanity");
2861   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2862 
2863   int n_queues = MAX2((int)ParallelGCThreads, 1);
2864   for (int i = 0; i < n_queues; i++) {
2865     _worker_cset_start_region[i] = NULL;
2866     _worker_cset_start_region_time_stamp[i] = 0;
2867   }
2868 }
2869 
2870 // Given the id of a worker, obtain or calculate a suitable
2871 // starting region for iterating over the current collection set.
2872 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2873   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2874 
2875   HeapRegion* result = NULL;
2876   unsigned gc_time_stamp = get_gc_time_stamp();
2877 
2878   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2879     // Cached starting region for current worker was set
2880     // during the current pause - so it's valid.
2881     // Note: the cached starting heap region may be NULL
2882     // (when the collection set is empty).
2883     result = _worker_cset_start_region[worker_i];
2884     assert(result == NULL || result->in_collection_set(), "sanity");
2885     return result;
2886   }
2887 
2888   // The cached entry was not valid so let's calculate
2889   // a suitable starting heap region for this worker.
2890 
2891   // We want the parallel threads to start their collection
2892   // set iteration at different collection set regions to
2893   // avoid contention.
2894   // If we have:
2895   //          n collection set regions
2896   //          p threads
2897   // Then thread t will start at region floor ((t * n) / p)
2898 
2899   result = g1_policy()->collection_set();
2900   if (G1CollectedHeap::use_parallel_gc_threads()) {
2901     uint cs_size = g1_policy()->cset_region_length();
2902     uint active_workers = workers()->active_workers();
2903     assert(UseDynamicNumberOfGCThreads ||
2904              active_workers == workers()->total_workers(),
2905              "Unless dynamic should use total workers");
2906 
2907     uint end_ind   = (cs_size * worker_i) / active_workers;
2908     uint start_ind = 0;
2909 
2910     if (worker_i > 0 &&
2911         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2912       // Previous workers starting region is valid
2913       // so let's iterate from there
2914       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2915       result = _worker_cset_start_region[worker_i - 1];
2916     }
2917 
2918     for (uint i = start_ind; i < end_ind; i++) {
2919       result = result->next_in_collection_set();
2920     }
2921   }
2922 
2923   // Note: the calculated starting heap region may be NULL
2924   // (when the collection set is empty).
2925   assert(result == NULL || result->in_collection_set(), "sanity");
2926   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2927          "should be updated only once per pause");
2928   _worker_cset_start_region[worker_i] = result;
2929   OrderAccess::storestore();
2930   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2931   return result;
2932 }
2933 
2934 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2935                                                      uint no_of_par_workers) {
2936   uint worker_num =
2937            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2938   assert(UseDynamicNumberOfGCThreads ||
2939          no_of_par_workers == workers()->total_workers(),
2940          "Non dynamic should use fixed number of workers");
2941   const uint start_index = n_regions() * worker_i / worker_num;
2942   return region_at(start_index);
2943 }
2944 
2945 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2946   HeapRegion* r = g1_policy()->collection_set();
2947   while (r != NULL) {
2948     HeapRegion* next = r->next_in_collection_set();
2949     if (cl->doHeapRegion(r)) {
2950       cl->incomplete();
2951       return;
2952     }
2953     r = next;
2954   }
2955 }
2956 
2957 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2958                                                   HeapRegionClosure *cl) {
2959   if (r == NULL) {
2960     // The CSet is empty so there's nothing to do.
2961     return;
2962   }
2963 
2964   assert(r->in_collection_set(),
2965          "Start region must be a member of the collection set.");
2966   HeapRegion* cur = r;
2967   while (cur != NULL) {
2968     HeapRegion* next = cur->next_in_collection_set();
2969     if (cl->doHeapRegion(cur) && false) {
2970       cl->incomplete();
2971       return;
2972     }
2973     cur = next;
2974   }
2975   cur = g1_policy()->collection_set();
2976   while (cur != r) {
2977     HeapRegion* next = cur->next_in_collection_set();
2978     if (cl->doHeapRegion(cur) && false) {
2979       cl->incomplete();
2980       return;
2981     }
2982     cur = next;
2983   }
2984 }
2985 
2986 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2987   return n_regions() > 0 ? region_at(0) : NULL;
2988 }
2989 
2990 
2991 Space* G1CollectedHeap::space_containing(const void* addr) const {
2992   Space* res = heap_region_containing(addr);
2993   return res;
2994 }
2995 
2996 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2997   Space* sp = space_containing(addr);
2998   if (sp != NULL) {
2999     return sp->block_start(addr);
3000   }
3001   return NULL;
3002 }
3003 
3004 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3005   Space* sp = space_containing(addr);
3006   assert(sp != NULL, "block_size of address outside of heap");
3007   return sp->block_size(addr);
3008 }
3009 
3010 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3011   Space* sp = space_containing(addr);
3012   return sp->block_is_obj(addr);
3013 }
3014 
3015 bool G1CollectedHeap::supports_tlab_allocation() const {
3016   return true;
3017 }
3018 
3019 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3020   return HeapRegion::GrainBytes;
3021 }
3022 
3023 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3024   // Return the remaining space in the cur alloc region, but not less than
3025   // the min TLAB size.
3026 
3027   // Also, this value can be at most the humongous object threshold,
3028   // since we can't allow tlabs to grow big enough to accommodate
3029   // humongous objects.
3030 
3031   HeapRegion* hr = _mutator_alloc_region.get();
3032   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3033   if (hr == NULL) {
3034     return max_tlab_size;
3035   } else {
3036     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3037   }
3038 }
3039 
3040 size_t G1CollectedHeap::max_capacity() const {
3041   return _g1_reserved.byte_size();
3042 }
3043 
3044 jlong G1CollectedHeap::millis_since_last_gc() {
3045   // assert(false, "NYI");
3046   return 0;
3047 }
3048 
3049 void G1CollectedHeap::prepare_for_verify() {
3050   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3051     ensure_parsability(false);
3052   }
3053   g1_rem_set()->prepare_for_verify();
3054 }
3055 
3056 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3057                                               VerifyOption vo) {
3058   switch (vo) {
3059   case VerifyOption_G1UsePrevMarking:
3060     return hr->obj_allocated_since_prev_marking(obj);
3061   case VerifyOption_G1UseNextMarking:
3062     return hr->obj_allocated_since_next_marking(obj);
3063   case VerifyOption_G1UseMarkWord:
3064     return false;
3065   default:
3066     ShouldNotReachHere();
3067   }
3068   return false; // keep some compilers happy
3069 }
3070 
3071 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3072   switch (vo) {
3073   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3074   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3075   case VerifyOption_G1UseMarkWord:    return NULL;
3076   default:                            ShouldNotReachHere();
3077   }
3078   return NULL; // keep some compilers happy
3079 }
3080 
3081 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3082   switch (vo) {
3083   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3084   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3085   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3086   default:                            ShouldNotReachHere();
3087   }
3088   return false; // keep some compilers happy
3089 }
3090 
3091 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3092   switch (vo) {
3093   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3094   case VerifyOption_G1UseNextMarking: return "NTAMS";
3095   case VerifyOption_G1UseMarkWord:    return "NONE";
3096   default:                            ShouldNotReachHere();
3097   }
3098   return NULL; // keep some compilers happy
3099 }
3100 
3101 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3102 //       pass it as the perm_blk to SharedHeap::process_strong_roots.
3103 //       When process_strong_roots stop calling perm_blk->younger_refs_iterate
3104 //       we can change this closure to extend the simpler OopClosure.
3105 class VerifyRootsClosure: public OopsInGenClosure {
3106 private:
3107   G1CollectedHeap* _g1h;
3108   VerifyOption     _vo;
3109   bool             _failures;
3110 public:
3111   // _vo == UsePrevMarking -> use "prev" marking information,
3112   // _vo == UseNextMarking -> use "next" marking information,
3113   // _vo == UseMarkWord    -> use mark word from object header.
3114   VerifyRootsClosure(VerifyOption vo) :
3115     _g1h(G1CollectedHeap::heap()),
3116     _vo(vo),
3117     _failures(false) { }
3118 
3119   bool failures() { return _failures; }
3120 
3121   template <class T> void do_oop_nv(T* p) {
3122     T heap_oop = oopDesc::load_heap_oop(p);
3123     if (!oopDesc::is_null(heap_oop)) {
3124       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3125       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3126         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3127                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3128         if (_vo == VerifyOption_G1UseMarkWord) {
3129           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3130         }
3131         obj->print_on(gclog_or_tty);
3132         _failures = true;
3133       }
3134     }
3135   }
3136 
3137   void do_oop(oop* p)       { do_oop_nv(p); }
3138   void do_oop(narrowOop* p) { do_oop_nv(p); }
3139 };
3140 
3141 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3142   G1CollectedHeap* _g1h;
3143   OopClosure* _root_cl;
3144   nmethod* _nm;
3145   VerifyOption _vo;
3146   bool _failures;
3147 
3148   template <class T> void do_oop_work(T* p) {
3149     // First verify that this root is live
3150     _root_cl->do_oop(p);
3151 
3152     if (!G1VerifyHeapRegionCodeRoots) {
3153       // We're not verifying the code roots attached to heap region.
3154       return;
3155     }
3156 
3157     // Don't check the code roots during marking verification in a full GC
3158     if (_vo == VerifyOption_G1UseMarkWord) {
3159       return;
3160     }
3161 
3162     // Now verify that the current nmethod (which contains p) is
3163     // in the code root list of the heap region containing the
3164     // object referenced by p.
3165 
3166     T heap_oop = oopDesc::load_heap_oop(p);
3167     if (!oopDesc::is_null(heap_oop)) {
3168       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3169 
3170       // Now fetch the region containing the object
3171       HeapRegion* hr = _g1h->heap_region_containing(obj);
3172       HeapRegionRemSet* hrrs = hr->rem_set();
3173       // Verify that the strong code root list for this region
3174       // contains the nmethod
3175       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3176         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3177                               "from nmethod "PTR_FORMAT" not in strong "
3178                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3179                               p, _nm, hr->bottom(), hr->end());
3180         _failures = true;
3181       }
3182     }
3183   }
3184 
3185 public:
3186   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3187     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3188 
3189   void do_oop(oop* p) { do_oop_work(p); }
3190   void do_oop(narrowOop* p) { do_oop_work(p); }
3191 
3192   void set_nmethod(nmethod* nm) { _nm = nm; }
3193   bool failures() { return _failures; }
3194 };
3195 
3196 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3197   G1VerifyCodeRootOopClosure* _oop_cl;
3198 
3199 public:
3200   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3201     _oop_cl(oop_cl) {}
3202 
3203   void do_code_blob(CodeBlob* cb) {
3204     nmethod* nm = cb->as_nmethod_or_null();
3205     if (nm != NULL) {
3206       _oop_cl->set_nmethod(nm);
3207       nm->oops_do(_oop_cl);
3208     }
3209   }
3210 };
3211 
3212 class YoungRefCounterClosure : public OopClosure {
3213   G1CollectedHeap* _g1h;
3214   int              _count;
3215  public:
3216   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3217   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3218   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3219 
3220   int count() { return _count; }
3221   void reset_count() { _count = 0; };
3222 };
3223 
3224 class VerifyKlassClosure: public KlassClosure {
3225   YoungRefCounterClosure _young_ref_counter_closure;
3226   OopClosure *_oop_closure;
3227  public:
3228   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3229   void do_klass(Klass* k) {
3230     k->oops_do(_oop_closure);
3231 
3232     _young_ref_counter_closure.reset_count();
3233     k->oops_do(&_young_ref_counter_closure);
3234     if (_young_ref_counter_closure.count() > 0) {
3235       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3236     }
3237   }
3238 };
3239 
3240 class VerifyLivenessOopClosure: public OopClosure {
3241   G1CollectedHeap* _g1h;
3242   VerifyOption _vo;
3243 public:
3244   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3245     _g1h(g1h), _vo(vo)
3246   { }
3247   void do_oop(narrowOop *p) { do_oop_work(p); }
3248   void do_oop(      oop *p) { do_oop_work(p); }
3249 
3250   template <class T> void do_oop_work(T *p) {
3251     oop obj = oopDesc::load_decode_heap_oop(p);
3252     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3253               "Dead object referenced by a not dead object");
3254   }
3255 };
3256 
3257 class VerifyObjsInRegionClosure: public ObjectClosure {
3258 private:
3259   G1CollectedHeap* _g1h;
3260   size_t _live_bytes;
3261   HeapRegion *_hr;
3262   VerifyOption _vo;
3263 public:
3264   // _vo == UsePrevMarking -> use "prev" marking information,
3265   // _vo == UseNextMarking -> use "next" marking information,
3266   // _vo == UseMarkWord    -> use mark word from object header.
3267   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3268     : _live_bytes(0), _hr(hr), _vo(vo) {
3269     _g1h = G1CollectedHeap::heap();
3270   }
3271   void do_object(oop o) {
3272     VerifyLivenessOopClosure isLive(_g1h, _vo);
3273     assert(o != NULL, "Huh?");
3274     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3275       // If the object is alive according to the mark word,
3276       // then verify that the marking information agrees.
3277       // Note we can't verify the contra-positive of the
3278       // above: if the object is dead (according to the mark
3279       // word), it may not be marked, or may have been marked
3280       // but has since became dead, or may have been allocated
3281       // since the last marking.
3282       if (_vo == VerifyOption_G1UseMarkWord) {
3283         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3284       }
3285 
3286       o->oop_iterate_no_header(&isLive);
3287       if (!_hr->obj_allocated_since_prev_marking(o)) {
3288         size_t obj_size = o->size();    // Make sure we don't overflow
3289         _live_bytes += (obj_size * HeapWordSize);
3290       }
3291     }
3292   }
3293   size_t live_bytes() { return _live_bytes; }
3294 };
3295 
3296 class PrintObjsInRegionClosure : public ObjectClosure {
3297   HeapRegion *_hr;
3298   G1CollectedHeap *_g1;
3299 public:
3300   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3301     _g1 = G1CollectedHeap::heap();
3302   };
3303 
3304   void do_object(oop o) {
3305     if (o != NULL) {
3306       HeapWord *start = (HeapWord *) o;
3307       size_t word_sz = o->size();
3308       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3309                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3310                           (void*) o, word_sz,
3311                           _g1->isMarkedPrev(o),
3312                           _g1->isMarkedNext(o),
3313                           _hr->obj_allocated_since_prev_marking(o));
3314       HeapWord *end = start + word_sz;
3315       HeapWord *cur;
3316       int *val;
3317       for (cur = start; cur < end; cur++) {
3318         val = (int *) cur;
3319         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3320       }
3321     }
3322   }
3323 };
3324 
3325 class VerifyRegionClosure: public HeapRegionClosure {
3326 private:
3327   bool             _par;
3328   VerifyOption     _vo;
3329   bool             _failures;
3330 public:
3331   // _vo == UsePrevMarking -> use "prev" marking information,
3332   // _vo == UseNextMarking -> use "next" marking information,
3333   // _vo == UseMarkWord    -> use mark word from object header.
3334   VerifyRegionClosure(bool par, VerifyOption vo)
3335     : _par(par),
3336       _vo(vo),
3337       _failures(false) {}
3338 
3339   bool failures() {
3340     return _failures;
3341   }
3342 
3343   bool doHeapRegion(HeapRegion* r) {
3344     if (!r->continuesHumongous()) {
3345       bool failures = false;
3346       r->verify(_vo, &failures);
3347       if (failures) {
3348         _failures = true;
3349       } else {
3350         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3351         r->object_iterate(&not_dead_yet_cl);
3352         if (_vo != VerifyOption_G1UseNextMarking) {
3353           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3354             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3355                                    "max_live_bytes "SIZE_FORMAT" "
3356                                    "< calculated "SIZE_FORMAT,
3357                                    r->bottom(), r->end(),
3358                                    r->max_live_bytes(),
3359                                  not_dead_yet_cl.live_bytes());
3360             _failures = true;
3361           }
3362         } else {
3363           // When vo == UseNextMarking we cannot currently do a sanity
3364           // check on the live bytes as the calculation has not been
3365           // finalized yet.
3366         }
3367       }
3368     }
3369     return false; // stop the region iteration if we hit a failure
3370   }
3371 };
3372 
3373 // This is the task used for parallel verification of the heap regions
3374 
3375 class G1ParVerifyTask: public AbstractGangTask {
3376 private:
3377   G1CollectedHeap* _g1h;
3378   VerifyOption     _vo;
3379   bool             _failures;
3380 
3381 public:
3382   // _vo == UsePrevMarking -> use "prev" marking information,
3383   // _vo == UseNextMarking -> use "next" marking information,
3384   // _vo == UseMarkWord    -> use mark word from object header.
3385   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3386     AbstractGangTask("Parallel verify task"),
3387     _g1h(g1h),
3388     _vo(vo),
3389     _failures(false) { }
3390 
3391   bool failures() {
3392     return _failures;
3393   }
3394 
3395   void work(uint worker_id) {
3396     HandleMark hm;
3397     VerifyRegionClosure blk(true, _vo);
3398     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3399                                           _g1h->workers()->active_workers(),
3400                                           HeapRegion::ParVerifyClaimValue);
3401     if (blk.failures()) {
3402       _failures = true;
3403     }
3404   }
3405 };
3406 
3407 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3408   if (SafepointSynchronize::is_at_safepoint()) {
3409     assert(Thread::current()->is_VM_thread(),
3410            "Expected to be executed serially by the VM thread at this point");
3411 
3412     if (!silent) { gclog_or_tty->print("Roots "); }
3413     VerifyRootsClosure rootsCl(vo);
3414     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3415     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3416     VerifyKlassClosure klassCl(this, &rootsCl);
3417 
3418     // We apply the relevant closures to all the oops in the
3419     // system dictionary, the string table and the code cache.
3420     const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3421 
3422     // Need cleared claim bits for the strong roots processing
3423     ClassLoaderDataGraph::clear_claimed_marks();
3424 
3425     process_strong_roots(true,      // activate StrongRootsScope
3426                          false,     // we set "is scavenging" to false,
3427                                     // so we don't reset the dirty cards.
3428                          ScanningOption(so),  // roots scanning options
3429                          &rootsCl,
3430                          &blobsCl,
3431                          &klassCl
3432                          );
3433 
3434     bool failures = rootsCl.failures() || codeRootsCl.failures();
3435 
3436     if (vo != VerifyOption_G1UseMarkWord) {
3437       // If we're verifying during a full GC then the region sets
3438       // will have been torn down at the start of the GC. Therefore
3439       // verifying the region sets will fail. So we only verify
3440       // the region sets when not in a full GC.
3441       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3442       verify_region_sets();
3443     }
3444 
3445     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3446     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3447       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3448              "sanity check");
3449 
3450       G1ParVerifyTask task(this, vo);
3451       assert(UseDynamicNumberOfGCThreads ||
3452         workers()->active_workers() == workers()->total_workers(),
3453         "If not dynamic should be using all the workers");
3454       int n_workers = workers()->active_workers();
3455       set_par_threads(n_workers);
3456       workers()->run_task(&task);
3457       set_par_threads(0);
3458       if (task.failures()) {
3459         failures = true;
3460       }
3461 
3462       // Checks that the expected amount of parallel work was done.
3463       // The implication is that n_workers is > 0.
3464       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3465              "sanity check");
3466 
3467       reset_heap_region_claim_values();
3468 
3469       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3470              "sanity check");
3471     } else {
3472       VerifyRegionClosure blk(false, vo);
3473       heap_region_iterate(&blk);
3474       if (blk.failures()) {
3475         failures = true;
3476       }
3477     }
3478     if (!silent) gclog_or_tty->print("RemSet ");
3479     rem_set()->verify();
3480 
3481     if (failures) {
3482       gclog_or_tty->print_cr("Heap:");
3483       // It helps to have the per-region information in the output to
3484       // help us track down what went wrong. This is why we call
3485       // print_extended_on() instead of print_on().
3486       print_extended_on(gclog_or_tty);
3487       gclog_or_tty->print_cr("");
3488 #ifndef PRODUCT
3489       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3490         concurrent_mark()->print_reachable("at-verification-failure",
3491                                            vo, false /* all */);
3492       }
3493 #endif
3494       gclog_or_tty->flush();
3495     }
3496     guarantee(!failures, "there should not have been any failures");
3497   } else {
3498     if (!silent)
3499       gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3500   }
3501 }
3502 
3503 void G1CollectedHeap::verify(bool silent) {
3504   verify(silent, VerifyOption_G1UsePrevMarking);
3505 }
3506 
3507 double G1CollectedHeap::verify(bool guard, const char* msg) {
3508   double verify_time_ms = 0.0;
3509 
3510   if (guard && total_collections() >= VerifyGCStartAt) {
3511     double verify_start = os::elapsedTime();
3512     HandleMark hm;  // Discard invalid handles created during verification
3513     prepare_for_verify();
3514     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3515     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3516   }
3517 
3518   return verify_time_ms;
3519 }
3520 
3521 void G1CollectedHeap::verify_before_gc() {
3522   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3523   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3524 }
3525 
3526 void G1CollectedHeap::verify_after_gc() {
3527   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3528   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3529 }
3530 
3531 class PrintRegionClosure: public HeapRegionClosure {
3532   outputStream* _st;
3533 public:
3534   PrintRegionClosure(outputStream* st) : _st(st) {}
3535   bool doHeapRegion(HeapRegion* r) {
3536     r->print_on(_st);
3537     return false;
3538   }
3539 };
3540 
3541 void G1CollectedHeap::print_on(outputStream* st) const {
3542   st->print(" %-20s", "garbage-first heap");
3543   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3544             capacity()/K, used_unlocked()/K);
3545   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3546             _g1_storage.low_boundary(),
3547             _g1_storage.high(),
3548             _g1_storage.high_boundary());
3549   st->cr();
3550   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3551   uint young_regions = _young_list->length();
3552   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3553             (size_t) young_regions * HeapRegion::GrainBytes / K);
3554   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3555   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3556             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3557   st->cr();
3558   MetaspaceAux::print_on(st);
3559 }
3560 
3561 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3562   print_on(st);
3563 
3564   // Print the per-region information.
3565   st->cr();
3566   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3567                "HS=humongous(starts), HC=humongous(continues), "
3568                "CS=collection set, F=free, TS=gc time stamp, "
3569                "PTAMS=previous top-at-mark-start, "
3570                "NTAMS=next top-at-mark-start)");
3571   PrintRegionClosure blk(st);
3572   heap_region_iterate(&blk);
3573 }
3574 
3575 void G1CollectedHeap::print_on_error(outputStream* st) const {
3576   this->CollectedHeap::print_on_error(st);
3577 
3578   if (_cm != NULL) {
3579     st->cr();
3580     _cm->print_on_error(st);
3581   }
3582 }
3583 
3584 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3585   if (G1CollectedHeap::use_parallel_gc_threads()) {
3586     workers()->print_worker_threads_on(st);
3587   }
3588   _cmThread->print_on(st);
3589   st->cr();
3590   _cm->print_worker_threads_on(st);
3591   _cg1r->print_worker_threads_on(st);
3592 }
3593 
3594 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3595   if (G1CollectedHeap::use_parallel_gc_threads()) {
3596     workers()->threads_do(tc);
3597   }
3598   tc->do_thread(_cmThread);
3599   _cg1r->threads_do(tc);
3600 }
3601 
3602 void G1CollectedHeap::print_tracing_info() const {
3603   // We'll overload this to mean "trace GC pause statistics."
3604   if (TraceGen0Time || TraceGen1Time) {
3605     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3606     // to that.
3607     g1_policy()->print_tracing_info();
3608   }
3609   if (G1SummarizeRSetStats) {
3610     g1_rem_set()->print_summary_info();
3611   }
3612   if (G1SummarizeConcMark) {
3613     concurrent_mark()->print_summary_info();
3614   }
3615   g1_policy()->print_yg_surv_rate_info();
3616   SpecializationStats::print();
3617 }
3618 
3619 #ifndef PRODUCT
3620 // Helpful for debugging RSet issues.
3621 
3622 class PrintRSetsClosure : public HeapRegionClosure {
3623 private:
3624   const char* _msg;
3625   size_t _occupied_sum;
3626 
3627 public:
3628   bool doHeapRegion(HeapRegion* r) {
3629     HeapRegionRemSet* hrrs = r->rem_set();
3630     size_t occupied = hrrs->occupied();
3631     _occupied_sum += occupied;
3632 
3633     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3634                            HR_FORMAT_PARAMS(r));
3635     if (occupied == 0) {
3636       gclog_or_tty->print_cr("  RSet is empty");
3637     } else {
3638       hrrs->print();
3639     }
3640     gclog_or_tty->print_cr("----------");
3641     return false;
3642   }
3643 
3644   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3645     gclog_or_tty->cr();
3646     gclog_or_tty->print_cr("========================================");
3647     gclog_or_tty->print_cr(msg);
3648     gclog_or_tty->cr();
3649   }
3650 
3651   ~PrintRSetsClosure() {
3652     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3653     gclog_or_tty->print_cr("========================================");
3654     gclog_or_tty->cr();
3655   }
3656 };
3657 
3658 void G1CollectedHeap::print_cset_rsets() {
3659   PrintRSetsClosure cl("Printing CSet RSets");
3660   collection_set_iterate(&cl);
3661 }
3662 
3663 void G1CollectedHeap::print_all_rsets() {
3664   PrintRSetsClosure cl("Printing All RSets");;
3665   heap_region_iterate(&cl);
3666 }
3667 #endif // PRODUCT
3668 
3669 G1CollectedHeap* G1CollectedHeap::heap() {
3670   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3671          "not a garbage-first heap");
3672   return _g1h;
3673 }
3674 
3675 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3676   // always_do_update_barrier = false;
3677   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3678   // Fill TLAB's and such
3679   ensure_parsability(true);
3680 
3681   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3682       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3683     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3684   }
3685 }
3686 
3687 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3688 
3689   if (G1SummarizeRSetStats &&
3690       (G1SummarizeRSetStatsPeriod > 0) &&
3691       // we are at the end of the GC. Total collections has already been increased.
3692       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3693     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3694   }
3695 
3696   // FIXME: what is this about?
3697   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3698   // is set.
3699   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3700                         "derived pointer present"));
3701   // always_do_update_barrier = true;
3702 
3703   // We have just completed a GC. Update the soft reference
3704   // policy with the new heap occupancy
3705   Universe::update_heap_info_at_gc();
3706 }
3707 
3708 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3709                                                unsigned int gc_count_before,
3710                                                bool* succeeded,
3711                                                GCCause::Cause gc_cause) {
3712   assert_heap_not_locked_and_not_at_safepoint();
3713   g1_policy()->record_stop_world_start();
3714   VM_G1IncCollectionPause op(gc_count_before,
3715                              word_size,
3716                              false, /* should_initiate_conc_mark */
3717                              g1_policy()->max_pause_time_ms(),
3718                              gc_cause);
3719   VMThread::execute(&op);
3720 
3721   HeapWord* result = op.result();
3722   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3723   assert(result == NULL || ret_succeeded,
3724          "the result should be NULL if the VM did not succeed");
3725   *succeeded = ret_succeeded;
3726 
3727   assert_heap_not_locked();
3728   return result;
3729 }
3730 
3731 void
3732 G1CollectedHeap::doConcurrentMark() {
3733   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3734   if (!_cmThread->in_progress()) {
3735     _cmThread->set_started();
3736     CGC_lock->notify();
3737   }
3738 }
3739 
3740 size_t G1CollectedHeap::pending_card_num() {
3741   size_t extra_cards = 0;
3742   JavaThread *curr = Threads::first();
3743   while (curr != NULL) {
3744     DirtyCardQueue& dcq = curr->dirty_card_queue();
3745     extra_cards += dcq.size();
3746     curr = curr->next();
3747   }
3748   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3749   size_t buffer_size = dcqs.buffer_size();
3750   size_t buffer_num = dcqs.completed_buffers_num();
3751 
3752   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3753   // in bytes - not the number of 'entries'. We need to convert
3754   // into a number of cards.
3755   return (buffer_size * buffer_num + extra_cards) / oopSize;
3756 }
3757 
3758 size_t G1CollectedHeap::cards_scanned() {
3759   return g1_rem_set()->cardsScanned();
3760 }
3761 
3762 void
3763 G1CollectedHeap::setup_surviving_young_words() {
3764   assert(_surviving_young_words == NULL, "pre-condition");
3765   uint array_length = g1_policy()->young_cset_region_length();
3766   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3767   if (_surviving_young_words == NULL) {
3768     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3769                           "Not enough space for young surv words summary.");
3770   }
3771   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3772 #ifdef ASSERT
3773   for (uint i = 0;  i < array_length; ++i) {
3774     assert( _surviving_young_words[i] == 0, "memset above" );
3775   }
3776 #endif // !ASSERT
3777 }
3778 
3779 void
3780 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3781   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3782   uint array_length = g1_policy()->young_cset_region_length();
3783   for (uint i = 0; i < array_length; ++i) {
3784     _surviving_young_words[i] += surv_young_words[i];
3785   }
3786 }
3787 
3788 void
3789 G1CollectedHeap::cleanup_surviving_young_words() {
3790   guarantee( _surviving_young_words != NULL, "pre-condition" );
3791   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3792   _surviving_young_words = NULL;
3793 }
3794 
3795 #ifdef ASSERT
3796 class VerifyCSetClosure: public HeapRegionClosure {
3797 public:
3798   bool doHeapRegion(HeapRegion* hr) {
3799     // Here we check that the CSet region's RSet is ready for parallel
3800     // iteration. The fields that we'll verify are only manipulated
3801     // when the region is part of a CSet and is collected. Afterwards,
3802     // we reset these fields when we clear the region's RSet (when the
3803     // region is freed) so they are ready when the region is
3804     // re-allocated. The only exception to this is if there's an
3805     // evacuation failure and instead of freeing the region we leave
3806     // it in the heap. In that case, we reset these fields during
3807     // evacuation failure handling.
3808     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3809 
3810     // Here's a good place to add any other checks we'd like to
3811     // perform on CSet regions.
3812     return false;
3813   }
3814 };
3815 #endif // ASSERT
3816 
3817 #if TASKQUEUE_STATS
3818 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3819   st->print_raw_cr("GC Task Stats");
3820   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3821   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3822 }
3823 
3824 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3825   print_taskqueue_stats_hdr(st);
3826 
3827   TaskQueueStats totals;
3828   const int n = workers() != NULL ? workers()->total_workers() : 1;
3829   for (int i = 0; i < n; ++i) {
3830     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3831     totals += task_queue(i)->stats;
3832   }
3833   st->print_raw("tot "); totals.print(st); st->cr();
3834 
3835   DEBUG_ONLY(totals.verify());
3836 }
3837 
3838 void G1CollectedHeap::reset_taskqueue_stats() {
3839   const int n = workers() != NULL ? workers()->total_workers() : 1;
3840   for (int i = 0; i < n; ++i) {
3841     task_queue(i)->stats.reset();
3842   }
3843 }
3844 #endif // TASKQUEUE_STATS
3845 
3846 void G1CollectedHeap::log_gc_header() {
3847   if (!G1Log::fine()) {
3848     return;
3849   }
3850 
3851   gclog_or_tty->date_stamp(PrintGCDateStamps);
3852   gclog_or_tty->stamp(PrintGCTimeStamps);
3853 
3854   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3855     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3856     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3857 
3858   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3859 }
3860 
3861 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3862   if (!G1Log::fine()) {
3863     return;
3864   }
3865 
3866   if (G1Log::finer()) {
3867     if (evacuation_failed()) {
3868       gclog_or_tty->print(" (to-space exhausted)");
3869     }
3870     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3871     g1_policy()->phase_times()->note_gc_end();
3872     g1_policy()->phase_times()->print(pause_time_sec);
3873     g1_policy()->print_detailed_heap_transition();
3874   } else {
3875     if (evacuation_failed()) {
3876       gclog_or_tty->print("--");
3877     }
3878     g1_policy()->print_heap_transition();
3879     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3880   }
3881   gclog_or_tty->flush();
3882 }
3883 
3884 bool
3885 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3886   assert_at_safepoint(true /* should_be_vm_thread */);
3887   guarantee(!is_gc_active(), "collection is not reentrant");
3888 
3889   if (GC_locker::check_active_before_gc()) {
3890     return false;
3891   }
3892 
3893   _gc_timer_stw->register_gc_start(os::elapsed_counter());
3894 
3895   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3896 
3897   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3898   ResourceMark rm;
3899 
3900   print_heap_before_gc();
3901   trace_heap_before_gc(_gc_tracer_stw);
3902 
3903   HRSPhaseSetter x(HRSPhaseEvacuation);
3904   verify_region_sets_optional();
3905   verify_dirty_young_regions();
3906 
3907   // This call will decide whether this pause is an initial-mark
3908   // pause. If it is, during_initial_mark_pause() will return true
3909   // for the duration of this pause.
3910   g1_policy()->decide_on_conc_mark_initiation();
3911 
3912   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3913   assert(!g1_policy()->during_initial_mark_pause() ||
3914           g1_policy()->gcs_are_young(), "sanity");
3915 
3916   // We also do not allow mixed GCs during marking.
3917   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3918 
3919   // Record whether this pause is an initial mark. When the current
3920   // thread has completed its logging output and it's safe to signal
3921   // the CM thread, the flag's value in the policy has been reset.
3922   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3923 
3924   // Inner scope for scope based logging, timers, and stats collection
3925   {
3926     EvacuationInfo evacuation_info;
3927 
3928     if (g1_policy()->during_initial_mark_pause()) {
3929       // We are about to start a marking cycle, so we increment the
3930       // full collection counter.
3931       increment_old_marking_cycles_started();
3932       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3933     }
3934 
3935     _gc_tracer_stw->report_yc_type(yc_type());
3936 
3937     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3938 
3939     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3940                                 workers()->active_workers() : 1);
3941     double pause_start_sec = os::elapsedTime();
3942     g1_policy()->phase_times()->note_gc_start(active_workers);
3943     log_gc_header();
3944 
3945     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3946     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3947 
3948     // If the secondary_free_list is not empty, append it to the
3949     // free_list. No need to wait for the cleanup operation to finish;
3950     // the region allocation code will check the secondary_free_list
3951     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3952     // set, skip this step so that the region allocation code has to
3953     // get entries from the secondary_free_list.
3954     if (!G1StressConcRegionFreeing) {
3955       append_secondary_free_list_if_not_empty_with_lock();
3956     }
3957 
3958     assert(check_young_list_well_formed(), "young list should be well formed");
3959     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3960            "sanity check");
3961 
3962     // Don't dynamically change the number of GC threads this early.  A value of
3963     // 0 is used to indicate serial work.  When parallel work is done,
3964     // it will be set.
3965 
3966     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3967       IsGCActiveMark x;
3968 
3969       gc_prologue(false);
3970       increment_total_collections(false /* full gc */);
3971       increment_gc_time_stamp();
3972 
3973       verify_before_gc();
3974 
3975       COMPILER2_PRESENT(DerivedPointerTable::clear());
3976 
3977       // Please see comment in g1CollectedHeap.hpp and
3978       // G1CollectedHeap::ref_processing_init() to see how
3979       // reference processing currently works in G1.
3980 
3981       // Enable discovery in the STW reference processor
3982       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3983                                             true /*verify_no_refs*/);
3984 
3985       {
3986         // We want to temporarily turn off discovery by the
3987         // CM ref processor, if necessary, and turn it back on
3988         // on again later if we do. Using a scoped
3989         // NoRefDiscovery object will do this.
3990         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3991 
3992         // Forget the current alloc region (we might even choose it to be part
3993         // of the collection set!).
3994         release_mutator_alloc_region();
3995 
3996         // We should call this after we retire the mutator alloc
3997         // region(s) so that all the ALLOC / RETIRE events are generated
3998         // before the start GC event.
3999         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4000 
4001         // This timing is only used by the ergonomics to handle our pause target.
4002         // It is unclear why this should not include the full pause. We will
4003         // investigate this in CR 7178365.
4004         //
4005         // Preserving the old comment here if that helps the investigation:
4006         //
4007         // The elapsed time induced by the start time below deliberately elides
4008         // the possible verification above.
4009         double sample_start_time_sec = os::elapsedTime();
4010 
4011 #if YOUNG_LIST_VERBOSE
4012         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4013         _young_list->print();
4014         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4015 #endif // YOUNG_LIST_VERBOSE
4016 
4017         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4018 
4019         double scan_wait_start = os::elapsedTime();
4020         // We have to wait until the CM threads finish scanning the
4021         // root regions as it's the only way to ensure that all the
4022         // objects on them have been correctly scanned before we start
4023         // moving them during the GC.
4024         bool waited = _cm->root_regions()->wait_until_scan_finished();
4025         double wait_time_ms = 0.0;
4026         if (waited) {
4027           double scan_wait_end = os::elapsedTime();
4028           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4029         }
4030         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4031 
4032 #if YOUNG_LIST_VERBOSE
4033         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4034         _young_list->print();
4035 #endif // YOUNG_LIST_VERBOSE
4036 
4037         if (g1_policy()->during_initial_mark_pause()) {
4038           concurrent_mark()->checkpointRootsInitialPre();
4039         }
4040 
4041 #if YOUNG_LIST_VERBOSE
4042         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4043         _young_list->print();
4044         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4045 #endif // YOUNG_LIST_VERBOSE
4046 
4047         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4048 
4049         _cm->note_start_of_gc();
4050         // We should not verify the per-thread SATB buffers given that
4051         // we have not filtered them yet (we'll do so during the
4052         // GC). We also call this after finalize_cset() to
4053         // ensure that the CSet has been finalized.
4054         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4055                                  true  /* verify_enqueued_buffers */,
4056                                  false /* verify_thread_buffers */,
4057                                  true  /* verify_fingers */);
4058 
4059         if (_hr_printer.is_active()) {
4060           HeapRegion* hr = g1_policy()->collection_set();
4061           while (hr != NULL) {
4062             G1HRPrinter::RegionType type;
4063             if (!hr->is_young()) {
4064               type = G1HRPrinter::Old;
4065             } else if (hr->is_survivor()) {
4066               type = G1HRPrinter::Survivor;
4067             } else {
4068               type = G1HRPrinter::Eden;
4069             }
4070             _hr_printer.cset(hr);
4071             hr = hr->next_in_collection_set();
4072           }
4073         }
4074 
4075 #ifdef ASSERT
4076         VerifyCSetClosure cl;
4077         collection_set_iterate(&cl);
4078 #endif // ASSERT
4079 
4080         setup_surviving_young_words();
4081 
4082         // Initialize the GC alloc regions.
4083         init_gc_alloc_regions(evacuation_info);
4084 
4085         // Actually do the work...
4086         evacuate_collection_set(evacuation_info);
4087 
4088         // We do this to mainly verify the per-thread SATB buffers
4089         // (which have been filtered by now) since we didn't verify
4090         // them earlier. No point in re-checking the stacks / enqueued
4091         // buffers given that the CSet has not changed since last time
4092         // we checked.
4093         _cm->verify_no_cset_oops(false /* verify_stacks */,
4094                                  false /* verify_enqueued_buffers */,
4095                                  true  /* verify_thread_buffers */,
4096                                  true  /* verify_fingers */);
4097 
4098         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4099         g1_policy()->clear_collection_set();
4100 
4101         cleanup_surviving_young_words();
4102 
4103         // Start a new incremental collection set for the next pause.
4104         g1_policy()->start_incremental_cset_building();
4105 
4106         // Clear the _cset_fast_test bitmap in anticipation of adding
4107         // regions to the incremental collection set for the next
4108         // evacuation pause.
4109         clear_cset_fast_test();
4110 
4111         _young_list->reset_sampled_info();
4112 
4113         // Don't check the whole heap at this point as the
4114         // GC alloc regions from this pause have been tagged
4115         // as survivors and moved on to the survivor list.
4116         // Survivor regions will fail the !is_young() check.
4117         assert(check_young_list_empty(false /* check_heap */),
4118           "young list should be empty");
4119 
4120 #if YOUNG_LIST_VERBOSE
4121         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4122         _young_list->print();
4123 #endif // YOUNG_LIST_VERBOSE
4124 
4125         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4126                                              _young_list->first_survivor_region(),
4127                                              _young_list->last_survivor_region());
4128 
4129         _young_list->reset_auxilary_lists();
4130 
4131         if (evacuation_failed()) {
4132           _summary_bytes_used = recalculate_used();
4133           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4134           for (uint i = 0; i < n_queues; i++) {
4135             if (_evacuation_failed_info_array[i].has_failed()) {
4136               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4137             }
4138           }
4139         } else {
4140           // The "used" of the the collection set have already been subtracted
4141           // when they were freed.  Add in the bytes evacuated.
4142           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4143         }
4144 
4145         if (g1_policy()->during_initial_mark_pause()) {
4146           // We have to do this before we notify the CM threads that
4147           // they can start working to make sure that all the
4148           // appropriate initialization is done on the CM object.
4149           concurrent_mark()->checkpointRootsInitialPost();
4150           set_marking_started();
4151           // Note that we don't actually trigger the CM thread at
4152           // this point. We do that later when we're sure that
4153           // the current thread has completed its logging output.
4154         }
4155 
4156         allocate_dummy_regions();
4157 
4158 #if YOUNG_LIST_VERBOSE
4159         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4160         _young_list->print();
4161         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4162 #endif // YOUNG_LIST_VERBOSE
4163 
4164         init_mutator_alloc_region();
4165 
4166         {
4167           size_t expand_bytes = g1_policy()->expansion_amount();
4168           if (expand_bytes > 0) {
4169             size_t bytes_before = capacity();
4170             // No need for an ergo verbose message here,
4171             // expansion_amount() does this when it returns a value > 0.
4172             if (!expand(expand_bytes)) {
4173               // We failed to expand the heap so let's verify that
4174               // committed/uncommitted amount match the backing store
4175               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4176               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4177             }
4178           }
4179         }
4180 
4181         // We redo the verification but now wrt to the new CSet which
4182         // has just got initialized after the previous CSet was freed.
4183         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4184                                  true  /* verify_enqueued_buffers */,
4185                                  true  /* verify_thread_buffers */,
4186                                  true  /* verify_fingers */);
4187         _cm->note_end_of_gc();
4188 
4189         // This timing is only used by the ergonomics to handle our pause target.
4190         // It is unclear why this should not include the full pause. We will
4191         // investigate this in CR 7178365.
4192         double sample_end_time_sec = os::elapsedTime();
4193         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4194         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4195 
4196         MemoryService::track_memory_usage();
4197 
4198         // In prepare_for_verify() below we'll need to scan the deferred
4199         // update buffers to bring the RSets up-to-date if
4200         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4201         // the update buffers we'll probably need to scan cards on the
4202         // regions we just allocated to (i.e., the GC alloc
4203         // regions). However, during the last GC we called
4204         // set_saved_mark() on all the GC alloc regions, so card
4205         // scanning might skip the [saved_mark_word()...top()] area of
4206         // those regions (i.e., the area we allocated objects into
4207         // during the last GC). But it shouldn't. Given that
4208         // saved_mark_word() is conditional on whether the GC time stamp
4209         // on the region is current or not, by incrementing the GC time
4210         // stamp here we invalidate all the GC time stamps on all the
4211         // regions and saved_mark_word() will simply return top() for
4212         // all the regions. This is a nicer way of ensuring this rather
4213         // than iterating over the regions and fixing them. In fact, the
4214         // GC time stamp increment here also ensures that
4215         // saved_mark_word() will return top() between pauses, i.e.,
4216         // during concurrent refinement. So we don't need the
4217         // is_gc_active() check to decided which top to use when
4218         // scanning cards (see CR 7039627).
4219         increment_gc_time_stamp();
4220 
4221         verify_after_gc();
4222 
4223         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4224         ref_processor_stw()->verify_no_references_recorded();
4225 
4226         // CM reference discovery will be re-enabled if necessary.
4227       }
4228 
4229       // We should do this after we potentially expand the heap so
4230       // that all the COMMIT events are generated before the end GC
4231       // event, and after we retire the GC alloc regions so that all
4232       // RETIRE events are generated before the end GC event.
4233       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4234 
4235       if (mark_in_progress()) {
4236         concurrent_mark()->update_g1_committed();
4237       }
4238 
4239 #ifdef TRACESPINNING
4240       ParallelTaskTerminator::print_termination_counts();
4241 #endif
4242 
4243       gc_epilogue(false);
4244     }
4245 
4246     // Print the remainder of the GC log output.
4247     log_gc_footer(os::elapsedTime() - pause_start_sec);
4248 
4249     // It is not yet to safe to tell the concurrent mark to
4250     // start as we have some optional output below. We don't want the
4251     // output from the concurrent mark thread interfering with this
4252     // logging output either.
4253 
4254     _hrs.verify_optional();
4255     verify_region_sets_optional();
4256 
4257     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4258     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4259 
4260     print_heap_after_gc();
4261     trace_heap_after_gc(_gc_tracer_stw);
4262 
4263     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4264     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4265     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4266     // before any GC notifications are raised.
4267     g1mm()->update_sizes();
4268 
4269     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4270     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4271     _gc_timer_stw->register_gc_end(os::elapsed_counter());
4272     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4273   }
4274   // It should now be safe to tell the concurrent mark thread to start
4275   // without its logging output interfering with the logging output
4276   // that came from the pause.
4277 
4278   if (should_start_conc_mark) {
4279     // CAUTION: after the doConcurrentMark() call below,
4280     // the concurrent marking thread(s) could be running
4281     // concurrently with us. Make sure that anything after
4282     // this point does not assume that we are the only GC thread
4283     // running. Note: of course, the actual marking work will
4284     // not start until the safepoint itself is released in
4285     // ConcurrentGCThread::safepoint_desynchronize().
4286     doConcurrentMark();
4287   }
4288 
4289   return true;
4290 }
4291 
4292 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4293 {
4294   size_t gclab_word_size;
4295   switch (purpose) {
4296     case GCAllocForSurvived:
4297       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4298       break;
4299     case GCAllocForTenured:
4300       gclab_word_size = _old_plab_stats.desired_plab_sz();
4301       break;
4302     default:
4303       assert(false, "unknown GCAllocPurpose");
4304       gclab_word_size = _old_plab_stats.desired_plab_sz();
4305       break;
4306   }
4307 
4308   // Prevent humongous PLAB sizes for two reasons:
4309   // * PLABs are allocated using a similar paths as oops, but should
4310   //   never be in a humongous region
4311   // * Allowing humongous PLABs needlessly churns the region free lists
4312   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4313 }
4314 
4315 void G1CollectedHeap::init_mutator_alloc_region() {
4316   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4317   _mutator_alloc_region.init();
4318 }
4319 
4320 void G1CollectedHeap::release_mutator_alloc_region() {
4321   _mutator_alloc_region.release();
4322   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4323 }
4324 
4325 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4326   assert_at_safepoint(true /* should_be_vm_thread */);
4327 
4328   _survivor_gc_alloc_region.init();
4329   _old_gc_alloc_region.init();
4330   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4331   _retained_old_gc_alloc_region = NULL;
4332 
4333   // We will discard the current GC alloc region if:
4334   // a) it's in the collection set (it can happen!),
4335   // b) it's already full (no point in using it),
4336   // c) it's empty (this means that it was emptied during
4337   // a cleanup and it should be on the free list now), or
4338   // d) it's humongous (this means that it was emptied
4339   // during a cleanup and was added to the free list, but
4340   // has been subsequently used to allocate a humongous
4341   // object that may be less than the region size).
4342   if (retained_region != NULL &&
4343       !retained_region->in_collection_set() &&
4344       !(retained_region->top() == retained_region->end()) &&
4345       !retained_region->is_empty() &&
4346       !retained_region->isHumongous()) {
4347     retained_region->set_saved_mark();
4348     // The retained region was added to the old region set when it was
4349     // retired. We have to remove it now, since we don't allow regions
4350     // we allocate to in the region sets. We'll re-add it later, when
4351     // it's retired again.
4352     _old_set.remove(retained_region);
4353     bool during_im = g1_policy()->during_initial_mark_pause();
4354     retained_region->note_start_of_copying(during_im);
4355     _old_gc_alloc_region.set(retained_region);
4356     _hr_printer.reuse(retained_region);
4357     evacuation_info.set_alloc_regions_used_before(retained_region->used());
4358   }
4359 }
4360 
4361 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4362   evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4363                                          _old_gc_alloc_region.count());
4364   _survivor_gc_alloc_region.release();
4365   // If we have an old GC alloc region to release, we'll save it in
4366   // _retained_old_gc_alloc_region. If we don't
4367   // _retained_old_gc_alloc_region will become NULL. This is what we
4368   // want either way so no reason to check explicitly for either
4369   // condition.
4370   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4371 
4372   if (ResizePLAB) {
4373     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4374     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4375   }
4376 }
4377 
4378 void G1CollectedHeap::abandon_gc_alloc_regions() {
4379   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4380   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4381   _retained_old_gc_alloc_region = NULL;
4382 }
4383 
4384 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4385   _drain_in_progress = false;
4386   set_evac_failure_closure(cl);
4387   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4388 }
4389 
4390 void G1CollectedHeap::finalize_for_evac_failure() {
4391   assert(_evac_failure_scan_stack != NULL &&
4392          _evac_failure_scan_stack->length() == 0,
4393          "Postcondition");
4394   assert(!_drain_in_progress, "Postcondition");
4395   delete _evac_failure_scan_stack;
4396   _evac_failure_scan_stack = NULL;
4397 }
4398 
4399 void G1CollectedHeap::remove_self_forwarding_pointers() {
4400   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4401 
4402   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4403 
4404   if (G1CollectedHeap::use_parallel_gc_threads()) {
4405     set_par_threads();
4406     workers()->run_task(&rsfp_task);
4407     set_par_threads(0);
4408   } else {
4409     rsfp_task.work(0);
4410   }
4411 
4412   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4413 
4414   // Reset the claim values in the regions in the collection set.
4415   reset_cset_heap_region_claim_values();
4416 
4417   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4418 
4419   // Now restore saved marks, if any.
4420   assert(_objs_with_preserved_marks.size() ==
4421             _preserved_marks_of_objs.size(), "Both or none.");
4422   while (!_objs_with_preserved_marks.is_empty()) {
4423     oop obj = _objs_with_preserved_marks.pop();
4424     markOop m = _preserved_marks_of_objs.pop();
4425     obj->set_mark(m);
4426   }
4427   _objs_with_preserved_marks.clear(true);
4428   _preserved_marks_of_objs.clear(true);
4429 }
4430 
4431 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4432   _evac_failure_scan_stack->push(obj);
4433 }
4434 
4435 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4436   assert(_evac_failure_scan_stack != NULL, "precondition");
4437 
4438   while (_evac_failure_scan_stack->length() > 0) {
4439      oop obj = _evac_failure_scan_stack->pop();
4440      _evac_failure_closure->set_region(heap_region_containing(obj));
4441      obj->oop_iterate_backwards(_evac_failure_closure);
4442   }
4443 }
4444 
4445 oop
4446 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4447                                                oop old) {
4448   assert(obj_in_cs(old),
4449          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4450                  (HeapWord*) old));
4451   markOop m = old->mark();
4452   oop forward_ptr = old->forward_to_atomic(old);
4453   if (forward_ptr == NULL) {
4454     // Forward-to-self succeeded.
4455     assert(_par_scan_state != NULL, "par scan state");
4456     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4457     uint queue_num = _par_scan_state->queue_num();
4458 
4459     _evacuation_failed = true;
4460     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4461     if (_evac_failure_closure != cl) {
4462       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4463       assert(!_drain_in_progress,
4464              "Should only be true while someone holds the lock.");
4465       // Set the global evac-failure closure to the current thread's.
4466       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4467       set_evac_failure_closure(cl);
4468       // Now do the common part.
4469       handle_evacuation_failure_common(old, m);
4470       // Reset to NULL.
4471       set_evac_failure_closure(NULL);
4472     } else {
4473       // The lock is already held, and this is recursive.
4474       assert(_drain_in_progress, "This should only be the recursive case.");
4475       handle_evacuation_failure_common(old, m);
4476     }
4477     return old;
4478   } else {
4479     // Forward-to-self failed. Either someone else managed to allocate
4480     // space for this object (old != forward_ptr) or they beat us in
4481     // self-forwarding it (old == forward_ptr).
4482     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4483            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4484                    "should not be in the CSet",
4485                    (HeapWord*) old, (HeapWord*) forward_ptr));
4486     return forward_ptr;
4487   }
4488 }
4489 
4490 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4491   preserve_mark_if_necessary(old, m);
4492 
4493   HeapRegion* r = heap_region_containing(old);
4494   if (!r->evacuation_failed()) {
4495     r->set_evacuation_failed(true);
4496     _hr_printer.evac_failure(r);
4497   }
4498 
4499   push_on_evac_failure_scan_stack(old);
4500 
4501   if (!_drain_in_progress) {
4502     // prevent recursion in copy_to_survivor_space()
4503     _drain_in_progress = true;
4504     drain_evac_failure_scan_stack();
4505     _drain_in_progress = false;
4506   }
4507 }
4508 
4509 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4510   assert(evacuation_failed(), "Oversaving!");
4511   // We want to call the "for_promotion_failure" version only in the
4512   // case of a promotion failure.
4513   if (m->must_be_preserved_for_promotion_failure(obj)) {
4514     _objs_with_preserved_marks.push(obj);
4515     _preserved_marks_of_objs.push(m);
4516   }
4517 }
4518 
4519 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4520                                                   size_t word_size) {
4521   if (purpose == GCAllocForSurvived) {
4522     HeapWord* result = survivor_attempt_allocation(word_size);
4523     if (result != NULL) {
4524       return result;
4525     } else {
4526       // Let's try to allocate in the old gen in case we can fit the
4527       // object there.
4528       return old_attempt_allocation(word_size);
4529     }
4530   } else {
4531     assert(purpose ==  GCAllocForTenured, "sanity");
4532     HeapWord* result = old_attempt_allocation(word_size);
4533     if (result != NULL) {
4534       return result;
4535     } else {
4536       // Let's try to allocate in the survivors in case we can fit the
4537       // object there.
4538       return survivor_attempt_allocation(word_size);
4539     }
4540   }
4541 
4542   ShouldNotReachHere();
4543   // Trying to keep some compilers happy.
4544   return NULL;
4545 }
4546 
4547 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4548   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4549 
4550 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4551   : _g1h(g1h),
4552     _refs(g1h->task_queue(queue_num)),
4553     _dcq(&g1h->dirty_card_queue_set()),
4554     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4555     _g1_rem(g1h->g1_rem_set()),
4556     _hash_seed(17), _queue_num(queue_num),
4557     _term_attempts(0),
4558     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4559     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4560     _age_table(false),
4561     _strong_roots_time(0), _term_time(0),
4562     _alloc_buffer_waste(0), _undo_waste(0) {
4563   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4564   // we "sacrifice" entry 0 to keep track of surviving bytes for
4565   // non-young regions (where the age is -1)
4566   // We also add a few elements at the beginning and at the end in
4567   // an attempt to eliminate cache contention
4568   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4569   uint array_length = PADDING_ELEM_NUM +
4570                       real_length +
4571                       PADDING_ELEM_NUM;
4572   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4573   if (_surviving_young_words_base == NULL)
4574     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4575                           "Not enough space for young surv histo.");
4576   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4577   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4578 
4579   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4580   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4581 
4582   _start = os::elapsedTime();
4583 }
4584 
4585 void
4586 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4587 {
4588   st->print_raw_cr("GC Termination Stats");
4589   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4590                    " ------waste (KiB)------");
4591   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4592                    "  total   alloc    undo");
4593   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4594                    " ------- ------- -------");
4595 }
4596 
4597 void
4598 G1ParScanThreadState::print_termination_stats(int i,
4599                                               outputStream* const st) const
4600 {
4601   const double elapsed_ms = elapsed_time() * 1000.0;
4602   const double s_roots_ms = strong_roots_time() * 1000.0;
4603   const double term_ms    = term_time() * 1000.0;
4604   st->print_cr("%3d %9.2f %9.2f %6.2f "
4605                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4606                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4607                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4608                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4609                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4610                alloc_buffer_waste() * HeapWordSize / K,
4611                undo_waste() * HeapWordSize / K);
4612 }
4613 
4614 #ifdef ASSERT
4615 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4616   assert(ref != NULL, "invariant");
4617   assert(UseCompressedOops, "sanity");
4618   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4619   oop p = oopDesc::load_decode_heap_oop(ref);
4620   assert(_g1h->is_in_g1_reserved(p),
4621          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4622   return true;
4623 }
4624 
4625 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4626   assert(ref != NULL, "invariant");
4627   if (has_partial_array_mask(ref)) {
4628     // Must be in the collection set--it's already been copied.
4629     oop p = clear_partial_array_mask(ref);
4630     assert(_g1h->obj_in_cs(p),
4631            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4632   } else {
4633     oop p = oopDesc::load_decode_heap_oop(ref);
4634     assert(_g1h->is_in_g1_reserved(p),
4635            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4636   }
4637   return true;
4638 }
4639 
4640 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4641   if (ref.is_narrow()) {
4642     return verify_ref((narrowOop*) ref);
4643   } else {
4644     return verify_ref((oop*) ref);
4645   }
4646 }
4647 #endif // ASSERT
4648 
4649 void G1ParScanThreadState::trim_queue() {
4650   assert(_evac_cl != NULL, "not set");
4651   assert(_evac_failure_cl != NULL, "not set");
4652   assert(_partial_scan_cl != NULL, "not set");
4653 
4654   StarTask ref;
4655   do {
4656     // Drain the overflow stack first, so other threads can steal.
4657     while (refs()->pop_overflow(ref)) {
4658       deal_with_reference(ref);
4659     }
4660 
4661     while (refs()->pop_local(ref)) {
4662       deal_with_reference(ref);
4663     }
4664   } while (!refs()->is_empty());
4665 }
4666 
4667 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4668                                      G1ParScanThreadState* par_scan_state) :
4669   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4670   _par_scan_state(par_scan_state),
4671   _worker_id(par_scan_state->queue_num()),
4672   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4673   _mark_in_progress(_g1->mark_in_progress()) { }
4674 
4675 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4676 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4677 #ifdef ASSERT
4678   HeapRegion* hr = _g1->heap_region_containing(obj);
4679   assert(hr != NULL, "sanity");
4680   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4681 #endif // ASSERT
4682 
4683   // We know that the object is not moving so it's safe to read its size.
4684   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4685 }
4686 
4687 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4688 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4689   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4690 #ifdef ASSERT
4691   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4692   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4693   assert(from_obj != to_obj, "should not be self-forwarded");
4694 
4695   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4696   assert(from_hr != NULL, "sanity");
4697   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4698 
4699   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4700   assert(to_hr != NULL, "sanity");
4701   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4702 #endif // ASSERT
4703 
4704   // The object might be in the process of being copied by another
4705   // worker so we cannot trust that its to-space image is
4706   // well-formed. So we have to read its size from its from-space
4707   // image which we know should not be changing.
4708   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4709 }
4710 
4711 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4712 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4713   ::copy_to_survivor_space(oop old) {
4714   size_t word_sz = old->size();
4715   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4716   // +1 to make the -1 indexes valid...
4717   int       young_index = from_region->young_index_in_cset()+1;
4718   assert( (from_region->is_young() && young_index >  0) ||
4719          (!from_region->is_young() && young_index == 0), "invariant" );
4720   G1CollectorPolicy* g1p = _g1->g1_policy();
4721   markOop m = old->mark();
4722   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4723                                            : m->age();
4724   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4725                                                              word_sz);
4726   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4727 #ifndef PRODUCT
4728   // Should this evacuation fail?
4729   if (_g1->evacuation_should_fail()) {
4730     if (obj_ptr != NULL) {
4731       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4732       obj_ptr = NULL;
4733     }
4734   }
4735 #endif // !PRODUCT
4736 
4737   if (obj_ptr == NULL) {
4738     // This will either forward-to-self, or detect that someone else has
4739     // installed a forwarding pointer.
4740     return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4741   }
4742 
4743   oop obj = oop(obj_ptr);
4744 
4745   // We're going to allocate linearly, so might as well prefetch ahead.
4746   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4747 
4748   oop forward_ptr = old->forward_to_atomic(obj);
4749   if (forward_ptr == NULL) {
4750     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4751     if (g1p->track_object_age(alloc_purpose)) {
4752       // We could simply do obj->incr_age(). However, this causes a
4753       // performance issue. obj->incr_age() will first check whether
4754       // the object has a displaced mark by checking its mark word;
4755       // getting the mark word from the new location of the object
4756       // stalls. So, given that we already have the mark word and we
4757       // are about to install it anyway, it's better to increase the
4758       // age on the mark word, when the object does not have a
4759       // displaced mark word. We're not expecting many objects to have
4760       // a displaced marked word, so that case is not optimized
4761       // further (it could be...) and we simply call obj->incr_age().
4762 
4763       if (m->has_displaced_mark_helper()) {
4764         // in this case, we have to install the mark word first,
4765         // otherwise obj looks to be forwarded (the old mark word,
4766         // which contains the forward pointer, was copied)
4767         obj->set_mark(m);
4768         obj->incr_age();
4769       } else {
4770         m = m->incr_age();
4771         obj->set_mark(m);
4772       }
4773       _par_scan_state->age_table()->add(obj, word_sz);
4774     } else {
4775       obj->set_mark(m);
4776     }
4777 
4778     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4779     surv_young_words[young_index] += word_sz;
4780 
4781     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4782       // We keep track of the next start index in the length field of
4783       // the to-space object. The actual length can be found in the
4784       // length field of the from-space object.
4785       arrayOop(obj)->set_length(0);
4786       oop* old_p = set_partial_array_mask(old);
4787       _par_scan_state->push_on_queue(old_p);
4788     } else {
4789       // No point in using the slower heap_region_containing() method,
4790       // given that we know obj is in the heap.
4791       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4792       obj->oop_iterate_backwards(&_scanner);
4793     }
4794   } else {
4795     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4796     obj = forward_ptr;
4797   }
4798   return obj;
4799 }
4800 
4801 template <class T>
4802 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4803   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4804     _scanned_klass->record_modified_oops();
4805   }
4806 }
4807 
4808 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4809 template <class T>
4810 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4811 ::do_oop_work(T* p) {
4812   oop obj = oopDesc::load_decode_heap_oop(p);
4813   assert(barrier != G1BarrierRS || obj != NULL,
4814          "Precondition: G1BarrierRS implies obj is non-NULL");
4815 
4816   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4817 
4818   // here the null check is implicit in the cset_fast_test() test
4819   if (_g1->in_cset_fast_test(obj)) {
4820     oop forwardee;
4821     if (obj->is_forwarded()) {
4822       forwardee = obj->forwardee();
4823     } else {
4824       forwardee = copy_to_survivor_space(obj);
4825     }
4826     assert(forwardee != NULL, "forwardee should not be NULL");
4827     oopDesc::encode_store_heap_oop(p, forwardee);
4828     if (do_mark_object && forwardee != obj) {
4829       // If the object is self-forwarded we don't need to explicitly
4830       // mark it, the evacuation failure protocol will do so.
4831       mark_forwarded_object(obj, forwardee);
4832     }
4833 
4834     // When scanning the RS, we only care about objs in CS.
4835     if (barrier == G1BarrierRS) {
4836       _par_scan_state->update_rs(_from, p, _worker_id);
4837     } else if (barrier == G1BarrierKlass) {
4838       do_klass_barrier(p, forwardee);
4839     }
4840   } else {
4841     // The object is not in collection set. If we're a root scanning
4842     // closure during an initial mark pause (i.e. do_mark_object will
4843     // be true) then attempt to mark the object.
4844     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4845       mark_object(obj);
4846     }
4847   }
4848 
4849   if (barrier == G1BarrierEvac && obj != NULL) {
4850     _par_scan_state->update_rs(_from, p, _worker_id);
4851   }
4852 
4853   if (do_gen_barrier && obj != NULL) {
4854     par_do_barrier(p);
4855   }
4856 }
4857 
4858 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4859 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4860 
4861 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4862   assert(has_partial_array_mask(p), "invariant");
4863   oop from_obj = clear_partial_array_mask(p);
4864 
4865   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4866   assert(from_obj->is_objArray(), "must be obj array");
4867   objArrayOop from_obj_array = objArrayOop(from_obj);
4868   // The from-space object contains the real length.
4869   int length                 = from_obj_array->length();
4870 
4871   assert(from_obj->is_forwarded(), "must be forwarded");
4872   oop to_obj                 = from_obj->forwardee();
4873   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4874   objArrayOop to_obj_array   = objArrayOop(to_obj);
4875   // We keep track of the next start index in the length field of the
4876   // to-space object.
4877   int next_index             = to_obj_array->length();
4878   assert(0 <= next_index && next_index < length,
4879          err_msg("invariant, next index: %d, length: %d", next_index, length));
4880 
4881   int start                  = next_index;
4882   int end                    = length;
4883   int remainder              = end - start;
4884   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4885   if (remainder > 2 * ParGCArrayScanChunk) {
4886     end = start + ParGCArrayScanChunk;
4887     to_obj_array->set_length(end);
4888     // Push the remainder before we process the range in case another
4889     // worker has run out of things to do and can steal it.
4890     oop* from_obj_p = set_partial_array_mask(from_obj);
4891     _par_scan_state->push_on_queue(from_obj_p);
4892   } else {
4893     assert(length == end, "sanity");
4894     // We'll process the final range for this object. Restore the length
4895     // so that the heap remains parsable in case of evacuation failure.
4896     to_obj_array->set_length(end);
4897   }
4898   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4899   // Process indexes [start,end). It will also process the header
4900   // along with the first chunk (i.e., the chunk with start == 0).
4901   // Note that at this point the length field of to_obj_array is not
4902   // correct given that we are using it to keep track of the next
4903   // start index. oop_iterate_range() (thankfully!) ignores the length
4904   // field and only relies on the start / end parameters.  It does
4905   // however return the size of the object which will be incorrect. So
4906   // we have to ignore it even if we wanted to use it.
4907   to_obj_array->oop_iterate_range(&_scanner, start, end);
4908 }
4909 
4910 class G1ParEvacuateFollowersClosure : public VoidClosure {
4911 protected:
4912   G1CollectedHeap*              _g1h;
4913   G1ParScanThreadState*         _par_scan_state;
4914   RefToScanQueueSet*            _queues;
4915   ParallelTaskTerminator*       _terminator;
4916 
4917   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4918   RefToScanQueueSet*      queues()         { return _queues; }
4919   ParallelTaskTerminator* terminator()     { return _terminator; }
4920 
4921 public:
4922   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4923                                 G1ParScanThreadState* par_scan_state,
4924                                 RefToScanQueueSet* queues,
4925                                 ParallelTaskTerminator* terminator)
4926     : _g1h(g1h), _par_scan_state(par_scan_state),
4927       _queues(queues), _terminator(terminator) {}
4928 
4929   void do_void();
4930 
4931 private:
4932   inline bool offer_termination();
4933 };
4934 
4935 bool G1ParEvacuateFollowersClosure::offer_termination() {
4936   G1ParScanThreadState* const pss = par_scan_state();
4937   pss->start_term_time();
4938   const bool res = terminator()->offer_termination();
4939   pss->end_term_time();
4940   return res;
4941 }
4942 
4943 void G1ParEvacuateFollowersClosure::do_void() {
4944   StarTask stolen_task;
4945   G1ParScanThreadState* const pss = par_scan_state();
4946   pss->trim_queue();
4947 
4948   do {
4949     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4950       assert(pss->verify_task(stolen_task), "sanity");
4951       if (stolen_task.is_narrow()) {
4952         pss->deal_with_reference((narrowOop*) stolen_task);
4953       } else {
4954         pss->deal_with_reference((oop*) stolen_task);
4955       }
4956 
4957       // We've just processed a reference and we might have made
4958       // available new entries on the queues. So we have to make sure
4959       // we drain the queues as necessary.
4960       pss->trim_queue();
4961     }
4962   } while (!offer_termination());
4963 
4964   pss->retire_alloc_buffers();
4965 }
4966 
4967 class G1KlassScanClosure : public KlassClosure {
4968  G1ParCopyHelper* _closure;
4969  bool             _process_only_dirty;
4970  int              _count;
4971  public:
4972   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4973       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4974   void do_klass(Klass* klass) {
4975     // If the klass has not been dirtied we know that there's
4976     // no references into  the young gen and we can skip it.
4977    if (!_process_only_dirty || klass->has_modified_oops()) {
4978       // Clean the klass since we're going to scavenge all the metadata.
4979       klass->clear_modified_oops();
4980 
4981       // Tell the closure that this klass is the Klass to scavenge
4982       // and is the one to dirty if oops are left pointing into the young gen.
4983       _closure->set_scanned_klass(klass);
4984 
4985       klass->oops_do(_closure);
4986 
4987       _closure->set_scanned_klass(NULL);
4988     }
4989     _count++;
4990   }
4991 };
4992 
4993 class G1ParTask : public AbstractGangTask {
4994 protected:
4995   G1CollectedHeap*       _g1h;
4996   RefToScanQueueSet      *_queues;
4997   ParallelTaskTerminator _terminator;
4998   uint _n_workers;
4999 
5000   Mutex _stats_lock;
5001   Mutex* stats_lock() { return &_stats_lock; }
5002 
5003   size_t getNCards() {
5004     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5005       / G1BlockOffsetSharedArray::N_bytes;
5006   }
5007 
5008 public:
5009   G1ParTask(G1CollectedHeap* g1h,
5010             RefToScanQueueSet *task_queues)
5011     : AbstractGangTask("G1 collection"),
5012       _g1h(g1h),
5013       _queues(task_queues),
5014       _terminator(0, _queues),
5015       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
5016   {}
5017 
5018   RefToScanQueueSet* queues() { return _queues; }
5019 
5020   RefToScanQueue *work_queue(int i) {
5021     return queues()->queue(i);
5022   }
5023 
5024   ParallelTaskTerminator* terminator() { return &_terminator; }
5025 
5026   virtual void set_for_termination(int active_workers) {
5027     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5028     // in the young space (_par_seq_tasks) in the G1 heap
5029     // for SequentialSubTasksDone.
5030     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5031     // both of which need setting by set_n_termination().
5032     _g1h->SharedHeap::set_n_termination(active_workers);
5033     _g1h->set_n_termination(active_workers);
5034     terminator()->reset_for_reuse(active_workers);
5035     _n_workers = active_workers;
5036   }
5037 
5038   void work(uint worker_id) {
5039     if (worker_id >= _n_workers) return;  // no work needed this round
5040 
5041     double start_time_ms = os::elapsedTime() * 1000.0;
5042     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5043 
5044     {
5045       ResourceMark rm;
5046       HandleMark   hm;
5047 
5048       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
5049 
5050       G1ParScanThreadState            pss(_g1h, worker_id);
5051       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
5052       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5053       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
5054 
5055       pss.set_evac_closure(&scan_evac_cl);
5056       pss.set_evac_failure_closure(&evac_failure_cl);
5057       pss.set_partial_scan_closure(&partial_scan_cl);
5058 
5059       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
5060       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
5061 
5062       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5063       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5064 
5065       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
5066       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5067       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5068 
5069       OopClosure*                    scan_root_cl = &only_scan_root_cl;
5070       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
5071 
5072       if (_g1h->g1_policy()->during_initial_mark_pause()) {
5073         // We also need to mark copied objects.
5074         scan_root_cl = &scan_mark_root_cl;
5075         scan_klasses_cl = &scan_mark_klasses_cl_s;
5076       }
5077 
5078       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
5079 
5080       // Don't scan the scavengable methods in the code cache as part
5081       // of strong root scanning. The code roots that point into a
5082       // region in the collection set are scanned when we scan the
5083       // region's RSet.
5084       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5085 
5086       pss.start_strong_roots();
5087       _g1h->g1_process_strong_roots(/* is scavenging */ true,
5088                                     SharedHeap::ScanningOption(so),
5089                                     scan_root_cl,
5090                                     &push_heap_rs_cl,
5091                                     scan_klasses_cl,
5092                                     worker_id);
5093       pss.end_strong_roots();
5094 
5095       {
5096         double start = os::elapsedTime();
5097         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5098         evac.do_void();
5099         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5100         double term_ms = pss.term_time()*1000.0;
5101         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5102         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5103       }
5104       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5105       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5106 
5107       if (ParallelGCVerbose) {
5108         MutexLocker x(stats_lock());
5109         pss.print_termination_stats(worker_id);
5110       }
5111 
5112       assert(pss.refs()->is_empty(), "should be empty");
5113 
5114       // Close the inner scope so that the ResourceMark and HandleMark
5115       // destructors are executed here and are included as part of the
5116       // "GC Worker Time".
5117     }
5118 
5119     double end_time_ms = os::elapsedTime() * 1000.0;
5120     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5121   }
5122 };
5123 
5124 // *** Common G1 Evacuation Stuff
5125 
5126 // This method is run in a GC worker.
5127 
5128 void
5129 G1CollectedHeap::
5130 g1_process_strong_roots(bool is_scavenging,
5131                         ScanningOption so,
5132                         OopClosure* scan_non_heap_roots,
5133                         OopsInHeapRegionClosure* scan_rs,
5134                         G1KlassScanClosure* scan_klasses,
5135                         int worker_i) {
5136 
5137   // First scan the strong roots
5138   double ext_roots_start = os::elapsedTime();
5139   double closure_app_time_sec = 0.0;
5140 
5141   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5142 
5143   assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5144   // Walk the code cache/strong code roots w/o buffering, because StarTask
5145   // cannot handle unaligned oop locations.
5146   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5147 
5148   process_strong_roots(false, // no scoping; this is parallel code
5149                        is_scavenging, so,
5150                        &buf_scan_non_heap_roots,
5151                        &eager_scan_code_roots,
5152                        scan_klasses
5153                        );
5154 
5155   // Now the CM ref_processor roots.
5156   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5157     // We need to treat the discovered reference lists of the
5158     // concurrent mark ref processor as roots and keep entries
5159     // (which are added by the marking threads) on them live
5160     // until they can be processed at the end of marking.
5161     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5162   }
5163 
5164   // Finish up any enqueued closure apps (attributed as object copy time).
5165   buf_scan_non_heap_roots.done();
5166 
5167   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5168 
5169   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5170 
5171   double ext_root_time_ms =
5172     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5173 
5174   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5175 
5176   // During conc marking we have to filter the per-thread SATB buffers
5177   // to make sure we remove any oops into the CSet (which will show up
5178   // as implicitly live).
5179   double satb_filtering_ms = 0.0;
5180   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5181     if (mark_in_progress()) {
5182       double satb_filter_start = os::elapsedTime();
5183 
5184       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5185 
5186       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5187     }
5188   }
5189   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5190 
5191   // If this is an initial mark pause, and we're not scanning
5192   // the entire code cache, we need to mark the oops in the
5193   // strong code root lists for the regions that are not in
5194   // the collection set.
5195   // Note all threads participate in this set of root tasks.
5196   double mark_strong_code_roots_ms = 0.0;
5197   if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5198     double mark_strong_roots_start = os::elapsedTime();
5199     mark_strong_code_roots(worker_i);
5200     mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5201   }
5202   g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5203 
5204   // Now scan the complement of the collection set.
5205   if (scan_rs != NULL) {
5206     g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5207   }
5208   _process_strong_tasks->all_tasks_completed();
5209 }
5210 
5211 void
5212 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5213   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5214   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5215 }
5216 
5217 // Weak Reference Processing support
5218 
5219 // An always "is_alive" closure that is used to preserve referents.
5220 // If the object is non-null then it's alive.  Used in the preservation
5221 // of referent objects that are pointed to by reference objects
5222 // discovered by the CM ref processor.
5223 class G1AlwaysAliveClosure: public BoolObjectClosure {
5224   G1CollectedHeap* _g1;
5225 public:
5226   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5227   bool do_object_b(oop p) {
5228     if (p != NULL) {
5229       return true;
5230     }
5231     return false;
5232   }
5233 };
5234 
5235 bool G1STWIsAliveClosure::do_object_b(oop p) {
5236   // An object is reachable if it is outside the collection set,
5237   // or is inside and copied.
5238   return !_g1->obj_in_cs(p) || p->is_forwarded();
5239 }
5240 
5241 // Non Copying Keep Alive closure
5242 class G1KeepAliveClosure: public OopClosure {
5243   G1CollectedHeap* _g1;
5244 public:
5245   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5246   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5247   void do_oop(      oop* p) {
5248     oop obj = *p;
5249 
5250     if (_g1->obj_in_cs(obj)) {
5251       assert( obj->is_forwarded(), "invariant" );
5252       *p = obj->forwardee();
5253     }
5254   }
5255 };
5256 
5257 // Copying Keep Alive closure - can be called from both
5258 // serial and parallel code as long as different worker
5259 // threads utilize different G1ParScanThreadState instances
5260 // and different queues.
5261 
5262 class G1CopyingKeepAliveClosure: public OopClosure {
5263   G1CollectedHeap*         _g1h;
5264   OopClosure*              _copy_non_heap_obj_cl;
5265   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5266   G1ParScanThreadState*    _par_scan_state;
5267 
5268 public:
5269   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5270                             OopClosure* non_heap_obj_cl,
5271                             OopsInHeapRegionClosure* metadata_obj_cl,
5272                             G1ParScanThreadState* pss):
5273     _g1h(g1h),
5274     _copy_non_heap_obj_cl(non_heap_obj_cl),
5275     _copy_metadata_obj_cl(metadata_obj_cl),
5276     _par_scan_state(pss)
5277   {}
5278 
5279   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5280   virtual void do_oop(      oop* p) { do_oop_work(p); }
5281 
5282   template <class T> void do_oop_work(T* p) {
5283     oop obj = oopDesc::load_decode_heap_oop(p);
5284 
5285     if (_g1h->obj_in_cs(obj)) {
5286       // If the referent object has been forwarded (either copied
5287       // to a new location or to itself in the event of an
5288       // evacuation failure) then we need to update the reference
5289       // field and, if both reference and referent are in the G1
5290       // heap, update the RSet for the referent.
5291       //
5292       // If the referent has not been forwarded then we have to keep
5293       // it alive by policy. Therefore we have copy the referent.
5294       //
5295       // If the reference field is in the G1 heap then we can push
5296       // on the PSS queue. When the queue is drained (after each
5297       // phase of reference processing) the object and it's followers
5298       // will be copied, the reference field set to point to the
5299       // new location, and the RSet updated. Otherwise we need to
5300       // use the the non-heap or metadata closures directly to copy
5301       // the referent object and update the pointer, while avoiding
5302       // updating the RSet.
5303 
5304       if (_g1h->is_in_g1_reserved(p)) {
5305         _par_scan_state->push_on_queue(p);
5306       } else {
5307         assert(!ClassLoaderDataGraph::contains((address)p),
5308                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5309                               PTR_FORMAT, p));
5310           _copy_non_heap_obj_cl->do_oop(p);
5311         }
5312       }
5313     }
5314 };
5315 
5316 // Serial drain queue closure. Called as the 'complete_gc'
5317 // closure for each discovered list in some of the
5318 // reference processing phases.
5319 
5320 class G1STWDrainQueueClosure: public VoidClosure {
5321 protected:
5322   G1CollectedHeap* _g1h;
5323   G1ParScanThreadState* _par_scan_state;
5324 
5325   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5326 
5327 public:
5328   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5329     _g1h(g1h),
5330     _par_scan_state(pss)
5331   { }
5332 
5333   void do_void() {
5334     G1ParScanThreadState* const pss = par_scan_state();
5335     pss->trim_queue();
5336   }
5337 };
5338 
5339 // Parallel Reference Processing closures
5340 
5341 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5342 // processing during G1 evacuation pauses.
5343 
5344 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5345 private:
5346   G1CollectedHeap*   _g1h;
5347   RefToScanQueueSet* _queues;
5348   FlexibleWorkGang*  _workers;
5349   int                _active_workers;
5350 
5351 public:
5352   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5353                         FlexibleWorkGang* workers,
5354                         RefToScanQueueSet *task_queues,
5355                         int n_workers) :
5356     _g1h(g1h),
5357     _queues(task_queues),
5358     _workers(workers),
5359     _active_workers(n_workers)
5360   {
5361     assert(n_workers > 0, "shouldn't call this otherwise");
5362   }
5363 
5364   // Executes the given task using concurrent marking worker threads.
5365   virtual void execute(ProcessTask& task);
5366   virtual void execute(EnqueueTask& task);
5367 };
5368 
5369 // Gang task for possibly parallel reference processing
5370 
5371 class G1STWRefProcTaskProxy: public AbstractGangTask {
5372   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5373   ProcessTask&     _proc_task;
5374   G1CollectedHeap* _g1h;
5375   RefToScanQueueSet *_task_queues;
5376   ParallelTaskTerminator* _terminator;
5377 
5378 public:
5379   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5380                      G1CollectedHeap* g1h,
5381                      RefToScanQueueSet *task_queues,
5382                      ParallelTaskTerminator* terminator) :
5383     AbstractGangTask("Process reference objects in parallel"),
5384     _proc_task(proc_task),
5385     _g1h(g1h),
5386     _task_queues(task_queues),
5387     _terminator(terminator)
5388   {}
5389 
5390   virtual void work(uint worker_id) {
5391     // The reference processing task executed by a single worker.
5392     ResourceMark rm;
5393     HandleMark   hm;
5394 
5395     G1STWIsAliveClosure is_alive(_g1h);
5396 
5397     G1ParScanThreadState pss(_g1h, worker_id);
5398 
5399     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5400     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5401     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5402 
5403     pss.set_evac_closure(&scan_evac_cl);
5404     pss.set_evac_failure_closure(&evac_failure_cl);
5405     pss.set_partial_scan_closure(&partial_scan_cl);
5406 
5407     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5408     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5409 
5410     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5411     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5412 
5413     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5414     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5415 
5416     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5417       // We also need to mark copied objects.
5418       copy_non_heap_cl = &copy_mark_non_heap_cl;
5419       copy_metadata_cl = &copy_mark_metadata_cl;
5420     }
5421 
5422     // Keep alive closure.
5423     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5424 
5425     // Complete GC closure
5426     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5427 
5428     // Call the reference processing task's work routine.
5429     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5430 
5431     // Note we cannot assert that the refs array is empty here as not all
5432     // of the processing tasks (specifically phase2 - pp2_work) execute
5433     // the complete_gc closure (which ordinarily would drain the queue) so
5434     // the queue may not be empty.
5435   }
5436 };
5437 
5438 // Driver routine for parallel reference processing.
5439 // Creates an instance of the ref processing gang
5440 // task and has the worker threads execute it.
5441 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5442   assert(_workers != NULL, "Need parallel worker threads.");
5443 
5444   ParallelTaskTerminator terminator(_active_workers, _queues);
5445   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5446 
5447   _g1h->set_par_threads(_active_workers);
5448   _workers->run_task(&proc_task_proxy);
5449   _g1h->set_par_threads(0);
5450 }
5451 
5452 // Gang task for parallel reference enqueueing.
5453 
5454 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5455   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5456   EnqueueTask& _enq_task;
5457 
5458 public:
5459   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5460     AbstractGangTask("Enqueue reference objects in parallel"),
5461     _enq_task(enq_task)
5462   { }
5463 
5464   virtual void work(uint worker_id) {
5465     _enq_task.work(worker_id);
5466   }
5467 };
5468 
5469 // Driver routine for parallel reference enqueueing.
5470 // Creates an instance of the ref enqueueing gang
5471 // task and has the worker threads execute it.
5472 
5473 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5474   assert(_workers != NULL, "Need parallel worker threads.");
5475 
5476   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5477 
5478   _g1h->set_par_threads(_active_workers);
5479   _workers->run_task(&enq_task_proxy);
5480   _g1h->set_par_threads(0);
5481 }
5482 
5483 // End of weak reference support closures
5484 
5485 // Abstract task used to preserve (i.e. copy) any referent objects
5486 // that are in the collection set and are pointed to by reference
5487 // objects discovered by the CM ref processor.
5488 
5489 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5490 protected:
5491   G1CollectedHeap* _g1h;
5492   RefToScanQueueSet      *_queues;
5493   ParallelTaskTerminator _terminator;
5494   uint _n_workers;
5495 
5496 public:
5497   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5498     AbstractGangTask("ParPreserveCMReferents"),
5499     _g1h(g1h),
5500     _queues(task_queues),
5501     _terminator(workers, _queues),
5502     _n_workers(workers)
5503   { }
5504 
5505   void work(uint worker_id) {
5506     ResourceMark rm;
5507     HandleMark   hm;
5508 
5509     G1ParScanThreadState            pss(_g1h, worker_id);
5510     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5511     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5512     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5513 
5514     pss.set_evac_closure(&scan_evac_cl);
5515     pss.set_evac_failure_closure(&evac_failure_cl);
5516     pss.set_partial_scan_closure(&partial_scan_cl);
5517 
5518     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5519 
5520 
5521     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5522     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5523 
5524     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5525     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5526 
5527     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5528     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_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       copy_metadata_cl = &copy_mark_metadata_cl;
5534     }
5535 
5536     // Is alive closure
5537     G1AlwaysAliveClosure always_alive(_g1h);
5538 
5539     // Copying keep alive closure. Applied to referent objects that need
5540     // to be copied.
5541     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5542 
5543     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5544 
5545     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5546     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5547 
5548     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5549     // So this must be true - but assert just in case someone decides to
5550     // change the worker ids.
5551     assert(0 <= worker_id && worker_id < limit, "sanity");
5552     assert(!rp->discovery_is_atomic(), "check this code");
5553 
5554     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5555     for (uint idx = worker_id; idx < limit; idx += stride) {
5556       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5557 
5558       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5559       while (iter.has_next()) {
5560         // Since discovery is not atomic for the CM ref processor, we
5561         // can see some null referent objects.
5562         iter.load_ptrs(DEBUG_ONLY(true));
5563         oop ref = iter.obj();
5564 
5565         // This will filter nulls.
5566         if (iter.is_referent_alive()) {
5567           iter.make_referent_alive();
5568         }
5569         iter.move_to_next();
5570       }
5571     }
5572 
5573     // Drain the queue - which may cause stealing
5574     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5575     drain_queue.do_void();
5576     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5577     assert(pss.refs()->is_empty(), "should be");
5578   }
5579 };
5580 
5581 // Weak Reference processing during an evacuation pause (part 1).
5582 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5583   double ref_proc_start = os::elapsedTime();
5584 
5585   ReferenceProcessor* rp = _ref_processor_stw;
5586   assert(rp->discovery_enabled(), "should have been enabled");
5587 
5588   // Any reference objects, in the collection set, that were 'discovered'
5589   // by the CM ref processor should have already been copied (either by
5590   // applying the external root copy closure to the discovered lists, or
5591   // by following an RSet entry).
5592   //
5593   // But some of the referents, that are in the collection set, that these
5594   // reference objects point to may not have been copied: the STW ref
5595   // processor would have seen that the reference object had already
5596   // been 'discovered' and would have skipped discovering the reference,
5597   // but would not have treated the reference object as a regular oop.
5598   // As a result the copy closure would not have been applied to the
5599   // referent object.
5600   //
5601   // We need to explicitly copy these referent objects - the references
5602   // will be processed at the end of remarking.
5603   //
5604   // We also need to do this copying before we process the reference
5605   // objects discovered by the STW ref processor in case one of these
5606   // referents points to another object which is also referenced by an
5607   // object discovered by the STW ref processor.
5608 
5609   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5610            no_of_gc_workers == workers()->active_workers(),
5611            "Need to reset active GC workers");
5612 
5613   set_par_threads(no_of_gc_workers);
5614   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5615                                                  no_of_gc_workers,
5616                                                  _task_queues);
5617 
5618   if (G1CollectedHeap::use_parallel_gc_threads()) {
5619     workers()->run_task(&keep_cm_referents);
5620   } else {
5621     keep_cm_referents.work(0);
5622   }
5623 
5624   set_par_threads(0);
5625 
5626   // Closure to test whether a referent is alive.
5627   G1STWIsAliveClosure is_alive(this);
5628 
5629   // Even when parallel reference processing is enabled, the processing
5630   // of JNI refs is serial and performed serially by the current thread
5631   // rather than by a worker. The following PSS will be used for processing
5632   // JNI refs.
5633 
5634   // Use only a single queue for this PSS.
5635   G1ParScanThreadState pss(this, 0);
5636 
5637   // We do not embed a reference processor in the copying/scanning
5638   // closures while we're actually processing the discovered
5639   // reference objects.
5640   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5641   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5642   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5643 
5644   pss.set_evac_closure(&scan_evac_cl);
5645   pss.set_evac_failure_closure(&evac_failure_cl);
5646   pss.set_partial_scan_closure(&partial_scan_cl);
5647 
5648   assert(pss.refs()->is_empty(), "pre-condition");
5649 
5650   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5651   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5652 
5653   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5654   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5655 
5656   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5657   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5658 
5659   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5660     // We also need to mark copied objects.
5661     copy_non_heap_cl = &copy_mark_non_heap_cl;
5662     copy_metadata_cl = &copy_mark_metadata_cl;
5663   }
5664 
5665   // Keep alive closure.
5666   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5667 
5668   // Serial Complete GC closure
5669   G1STWDrainQueueClosure drain_queue(this, &pss);
5670 
5671   // Setup the soft refs policy...
5672   rp->setup_policy(false);
5673 
5674   ReferenceProcessorStats stats;
5675   if (!rp->processing_is_mt()) {
5676     // Serial reference processing...
5677     stats = rp->process_discovered_references(&is_alive,
5678                                               &keep_alive,
5679                                               &drain_queue,
5680                                               NULL,
5681                                               _gc_timer_stw);
5682   } else {
5683     // Parallel reference processing
5684     assert(rp->num_q() == no_of_gc_workers, "sanity");
5685     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5686 
5687     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5688     stats = rp->process_discovered_references(&is_alive,
5689                                               &keep_alive,
5690                                               &drain_queue,
5691                                               &par_task_executor,
5692                                               _gc_timer_stw);
5693   }
5694 
5695   _gc_tracer_stw->report_gc_reference_stats(stats);
5696   // We have completed copying any necessary live referent objects
5697   // (that were not copied during the actual pause) so we can
5698   // retire any active alloc buffers
5699   pss.retire_alloc_buffers();
5700   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5701 
5702   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5703   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5704 }
5705 
5706 // Weak Reference processing during an evacuation pause (part 2).
5707 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5708   double ref_enq_start = os::elapsedTime();
5709 
5710   ReferenceProcessor* rp = _ref_processor_stw;
5711   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5712 
5713   // Now enqueue any remaining on the discovered lists on to
5714   // the pending list.
5715   if (!rp->processing_is_mt()) {
5716     // Serial reference processing...
5717     rp->enqueue_discovered_references();
5718   } else {
5719     // Parallel reference enqueueing
5720 
5721     assert(no_of_gc_workers == workers()->active_workers(),
5722            "Need to reset active workers");
5723     assert(rp->num_q() == no_of_gc_workers, "sanity");
5724     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5725 
5726     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5727     rp->enqueue_discovered_references(&par_task_executor);
5728   }
5729 
5730   rp->verify_no_references_recorded();
5731   assert(!rp->discovery_enabled(), "should have been disabled");
5732 
5733   // FIXME
5734   // CM's reference processing also cleans up the string and symbol tables.
5735   // Should we do that here also? We could, but it is a serial operation
5736   // and could significantly increase the pause time.
5737 
5738   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5739   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5740 }
5741 
5742 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5743   _expand_heap_after_alloc_failure = true;
5744   _evacuation_failed = false;
5745 
5746   // Should G1EvacuationFailureALot be in effect for this GC?
5747   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5748 
5749   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5750 
5751   // Disable the hot card cache.
5752   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5753   hot_card_cache->reset_hot_cache_claimed_index();
5754   hot_card_cache->set_use_cache(false);
5755 
5756   uint n_workers;
5757   if (G1CollectedHeap::use_parallel_gc_threads()) {
5758     n_workers =
5759       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5760                                      workers()->active_workers(),
5761                                      Threads::number_of_non_daemon_threads());
5762     assert(UseDynamicNumberOfGCThreads ||
5763            n_workers == workers()->total_workers(),
5764            "If not dynamic should be using all the  workers");
5765     workers()->set_active_workers(n_workers);
5766     set_par_threads(n_workers);
5767   } else {
5768     assert(n_par_threads() == 0,
5769            "Should be the original non-parallel value");
5770     n_workers = 1;
5771   }
5772 
5773   G1ParTask g1_par_task(this, _task_queues);
5774 
5775   init_for_evac_failure(NULL);
5776 
5777   rem_set()->prepare_for_younger_refs_iterate(true);
5778 
5779   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5780   double start_par_time_sec = os::elapsedTime();
5781   double end_par_time_sec;
5782 
5783   {
5784     StrongRootsScope srs(this);
5785 
5786     if (G1CollectedHeap::use_parallel_gc_threads()) {
5787       // The individual threads will set their evac-failure closures.
5788       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5789       // These tasks use ShareHeap::_process_strong_tasks
5790       assert(UseDynamicNumberOfGCThreads ||
5791              workers()->active_workers() == workers()->total_workers(),
5792              "If not dynamic should be using all the  workers");
5793       workers()->run_task(&g1_par_task);
5794     } else {
5795       g1_par_task.set_for_termination(n_workers);
5796       g1_par_task.work(0);
5797     }
5798     end_par_time_sec = os::elapsedTime();
5799 
5800     // Closing the inner scope will execute the destructor
5801     // for the StrongRootsScope object. We record the current
5802     // elapsed time before closing the scope so that time
5803     // taken for the SRS destructor is NOT included in the
5804     // reported parallel time.
5805   }
5806 
5807   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5808   g1_policy()->phase_times()->record_par_time(par_time_ms);
5809 
5810   double code_root_fixup_time_ms =
5811         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5812   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5813 
5814   set_par_threads(0);
5815 
5816   // Process any discovered reference objects - we have
5817   // to do this _before_ we retire the GC alloc regions
5818   // as we may have to copy some 'reachable' referent
5819   // objects (and their reachable sub-graphs) that were
5820   // not copied during the pause.
5821   process_discovered_references(n_workers);
5822 
5823   // Weak root processing.
5824   {
5825     G1STWIsAliveClosure is_alive(this);
5826     G1KeepAliveClosure keep_alive(this);
5827     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5828   }
5829 
5830   release_gc_alloc_regions(n_workers, evacuation_info);
5831   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5832 
5833   // Reset and re-enable the hot card cache.
5834   // Note the counts for the cards in the regions in the
5835   // collection set are reset when the collection set is freed.
5836   hot_card_cache->reset_hot_cache();
5837   hot_card_cache->set_use_cache(true);
5838 
5839   // Migrate the strong code roots attached to each region in
5840   // the collection set. Ideally we would like to do this
5841   // after we have finished the scanning/evacuation of the
5842   // strong code roots for a particular heap region.
5843   migrate_strong_code_roots();
5844 
5845   if (g1_policy()->during_initial_mark_pause()) {
5846     // Reset the claim values set during marking the strong code roots
5847     reset_heap_region_claim_values();
5848   }
5849 
5850   finalize_for_evac_failure();
5851 
5852   if (evacuation_failed()) {
5853     remove_self_forwarding_pointers();
5854 
5855     // Reset the G1EvacuationFailureALot counters and flags
5856     // Note: the values are reset only when an actual
5857     // evacuation failure occurs.
5858     NOT_PRODUCT(reset_evacuation_should_fail();)
5859   }
5860 
5861   // Enqueue any remaining references remaining on the STW
5862   // reference processor's discovered lists. We need to do
5863   // this after the card table is cleaned (and verified) as
5864   // the act of enqueueing entries on to the pending list
5865   // will log these updates (and dirty their associated
5866   // cards). We need these updates logged to update any
5867   // RSets.
5868   enqueue_discovered_references(n_workers);
5869 
5870   if (G1DeferredRSUpdate) {
5871     RedirtyLoggedCardTableEntryFastClosure redirty;
5872     dirty_card_queue_set().set_closure(&redirty);
5873     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5874 
5875     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5876     dcq.merge_bufferlists(&dirty_card_queue_set());
5877     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5878   }
5879   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5880 }
5881 
5882 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5883                                      size_t* pre_used,
5884                                      FreeRegionList* free_list,
5885                                      OldRegionSet* old_proxy_set,
5886                                      HumongousRegionSet* humongous_proxy_set,
5887                                      HRRSCleanupTask* hrrs_cleanup_task,
5888                                      bool par) {
5889   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5890     if (hr->isHumongous()) {
5891       assert(hr->startsHumongous(), "we should only see starts humongous");
5892       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5893     } else {
5894       _old_set.remove_with_proxy(hr, old_proxy_set);
5895       free_region(hr, pre_used, free_list, par);
5896     }
5897   } else {
5898     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5899   }
5900 }
5901 
5902 void G1CollectedHeap::free_region(HeapRegion* hr,
5903                                   size_t* pre_used,
5904                                   FreeRegionList* free_list,
5905                                   bool par) {
5906   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5907   assert(!hr->is_empty(), "the region should not be empty");
5908   assert(free_list != NULL, "pre-condition");
5909 
5910   // Clear the card counts for this region.
5911   // Note: we only need to do this if the region is not young
5912   // (since we don't refine cards in young regions).
5913   if (!hr->is_young()) {
5914     _cg1r->hot_card_cache()->reset_card_counts(hr);
5915   }
5916   *pre_used += hr->used();
5917   hr->hr_clear(par, true /* clear_space */);
5918   free_list->add_as_head(hr);
5919 }
5920 
5921 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5922                                      size_t* pre_used,
5923                                      FreeRegionList* free_list,
5924                                      HumongousRegionSet* humongous_proxy_set,
5925                                      bool par) {
5926   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5927   assert(free_list != NULL, "pre-condition");
5928   assert(humongous_proxy_set != NULL, "pre-condition");
5929 
5930   size_t hr_used = hr->used();
5931   size_t hr_capacity = hr->capacity();
5932   size_t hr_pre_used = 0;
5933   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5934   // We need to read this before we make the region non-humongous,
5935   // otherwise the information will be gone.
5936   uint last_index = hr->last_hc_index();
5937   hr->set_notHumongous();
5938   free_region(hr, &hr_pre_used, free_list, par);
5939 
5940   uint i = hr->hrs_index() + 1;
5941   while (i < last_index) {
5942     HeapRegion* curr_hr = region_at(i);
5943     assert(curr_hr->continuesHumongous(), "invariant");
5944     curr_hr->set_notHumongous();
5945     free_region(curr_hr, &hr_pre_used, free_list, par);
5946     i += 1;
5947   }
5948   assert(hr_pre_used == hr_used,
5949          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5950                  "should be the same", hr_pre_used, hr_used));
5951   *pre_used += hr_pre_used;
5952 }
5953 
5954 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5955                                        FreeRegionList* free_list,
5956                                        OldRegionSet* old_proxy_set,
5957                                        HumongousRegionSet* humongous_proxy_set,
5958                                        bool par) {
5959   if (pre_used > 0) {
5960     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5961     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5962     assert(_summary_bytes_used >= pre_used,
5963            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5964                    "should be >= pre_used: "SIZE_FORMAT,
5965                    _summary_bytes_used, pre_used));
5966     _summary_bytes_used -= pre_used;
5967   }
5968   if (free_list != NULL && !free_list->is_empty()) {
5969     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5970     _free_list.add_as_head(free_list);
5971   }
5972   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5973     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5974     _old_set.update_from_proxy(old_proxy_set);
5975   }
5976   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5977     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5978     _humongous_set.update_from_proxy(humongous_proxy_set);
5979   }
5980 }
5981 
5982 class G1ParCleanupCTTask : public AbstractGangTask {
5983   CardTableModRefBS* _ct_bs;
5984   G1CollectedHeap* _g1h;
5985   HeapRegion* volatile _su_head;
5986 public:
5987   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5988                      G1CollectedHeap* g1h) :
5989     AbstractGangTask("G1 Par Cleanup CT Task"),
5990     _ct_bs(ct_bs), _g1h(g1h) { }
5991 
5992   void work(uint worker_id) {
5993     HeapRegion* r;
5994     while (r = _g1h->pop_dirty_cards_region()) {
5995       clear_cards(r);
5996     }
5997   }
5998 
5999   void clear_cards(HeapRegion* r) {
6000     // Cards of the survivors should have already been dirtied.
6001     if (!r->is_survivor()) {
6002       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6003     }
6004   }
6005 };
6006 
6007 #ifndef PRODUCT
6008 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6009   G1CollectedHeap* _g1h;
6010   CardTableModRefBS* _ct_bs;
6011 public:
6012   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
6013     : _g1h(g1h), _ct_bs(ct_bs) { }
6014   virtual bool doHeapRegion(HeapRegion* r) {
6015     if (r->is_survivor()) {
6016       _g1h->verify_dirty_region(r);
6017     } else {
6018       _g1h->verify_not_dirty_region(r);
6019     }
6020     return false;
6021   }
6022 };
6023 
6024 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6025   // All of the region should be clean.
6026   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
6027   MemRegion mr(hr->bottom(), hr->end());
6028   ct_bs->verify_not_dirty_region(mr);
6029 }
6030 
6031 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6032   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
6033   // dirty allocated blocks as they allocate them. The thread that
6034   // retires each region and replaces it with a new one will do a
6035   // maximal allocation to fill in [pre_dummy_top(),end()] but will
6036   // not dirty that area (one less thing to have to do while holding
6037   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6038   // is dirty.
6039   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
6040   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6041   ct_bs->verify_dirty_region(mr);
6042 }
6043 
6044 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6045   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
6046   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6047     verify_dirty_region(hr);
6048   }
6049 }
6050 
6051 void G1CollectedHeap::verify_dirty_young_regions() {
6052   verify_dirty_young_list(_young_list->first_region());
6053 }
6054 #endif
6055 
6056 void G1CollectedHeap::cleanUpCardTable() {
6057   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
6058   double start = os::elapsedTime();
6059 
6060   {
6061     // Iterate over the dirty cards region list.
6062     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6063 
6064     if (G1CollectedHeap::use_parallel_gc_threads()) {
6065       set_par_threads();
6066       workers()->run_task(&cleanup_task);
6067       set_par_threads(0);
6068     } else {
6069       while (_dirty_cards_region_list) {
6070         HeapRegion* r = _dirty_cards_region_list;
6071         cleanup_task.clear_cards(r);
6072         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6073         if (_dirty_cards_region_list == r) {
6074           // The last region.
6075           _dirty_cards_region_list = NULL;
6076         }
6077         r->set_next_dirty_cards_region(NULL);
6078       }
6079     }
6080 #ifndef PRODUCT
6081     if (G1VerifyCTCleanup || VerifyAfterGC) {
6082       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6083       heap_region_iterate(&cleanup_verifier);
6084     }
6085 #endif
6086   }
6087 
6088   double elapsed = os::elapsedTime() - start;
6089   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6090 }
6091 
6092 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6093   size_t pre_used = 0;
6094   FreeRegionList local_free_list("Local List for CSet Freeing");
6095 
6096   double young_time_ms     = 0.0;
6097   double non_young_time_ms = 0.0;
6098 
6099   // Since the collection set is a superset of the the young list,
6100   // all we need to do to clear the young list is clear its
6101   // head and length, and unlink any young regions in the code below
6102   _young_list->clear();
6103 
6104   G1CollectorPolicy* policy = g1_policy();
6105 
6106   double start_sec = os::elapsedTime();
6107   bool non_young = true;
6108 
6109   HeapRegion* cur = cs_head;
6110   int age_bound = -1;
6111   size_t rs_lengths = 0;
6112 
6113   while (cur != NULL) {
6114     assert(!is_on_master_free_list(cur), "sanity");
6115     if (non_young) {
6116       if (cur->is_young()) {
6117         double end_sec = os::elapsedTime();
6118         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6119         non_young_time_ms += elapsed_ms;
6120 
6121         start_sec = os::elapsedTime();
6122         non_young = false;
6123       }
6124     } else {
6125       if (!cur->is_young()) {
6126         double end_sec = os::elapsedTime();
6127         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6128         young_time_ms += elapsed_ms;
6129 
6130         start_sec = os::elapsedTime();
6131         non_young = true;
6132       }
6133     }
6134 
6135     rs_lengths += cur->rem_set()->occupied();
6136 
6137     HeapRegion* next = cur->next_in_collection_set();
6138     assert(cur->in_collection_set(), "bad CS");
6139     cur->set_next_in_collection_set(NULL);
6140     cur->set_in_collection_set(false);
6141 
6142     if (cur->is_young()) {
6143       int index = cur->young_index_in_cset();
6144       assert(index != -1, "invariant");
6145       assert((uint) index < policy->young_cset_region_length(), "invariant");
6146       size_t words_survived = _surviving_young_words[index];
6147       cur->record_surv_words_in_group(words_survived);
6148 
6149       // At this point the we have 'popped' cur from the collection set
6150       // (linked via next_in_collection_set()) but it is still in the
6151       // young list (linked via next_young_region()). Clear the
6152       // _next_young_region field.
6153       cur->set_next_young_region(NULL);
6154     } else {
6155       int index = cur->young_index_in_cset();
6156       assert(index == -1, "invariant");
6157     }
6158 
6159     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6160             (!cur->is_young() && cur->young_index_in_cset() == -1),
6161             "invariant" );
6162 
6163     if (!cur->evacuation_failed()) {
6164       MemRegion used_mr = cur->used_region();
6165 
6166       // And the region is empty.
6167       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6168       free_region(cur, &pre_used, &local_free_list, false /* par */);
6169     } else {
6170       cur->uninstall_surv_rate_group();
6171       if (cur->is_young()) {
6172         cur->set_young_index_in_cset(-1);
6173       }
6174       cur->set_not_young();
6175       cur->set_evacuation_failed(false);
6176       // The region is now considered to be old.
6177       _old_set.add(cur);
6178       evacuation_info.increment_collectionset_used_after(cur->used());
6179     }
6180     cur = next;
6181   }
6182 
6183   evacuation_info.set_regions_freed(local_free_list.length());
6184   policy->record_max_rs_lengths(rs_lengths);
6185   policy->cset_regions_freed();
6186 
6187   double end_sec = os::elapsedTime();
6188   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6189 
6190   if (non_young) {
6191     non_young_time_ms += elapsed_ms;
6192   } else {
6193     young_time_ms += elapsed_ms;
6194   }
6195 
6196   update_sets_after_freeing_regions(pre_used, &local_free_list,
6197                                     NULL /* old_proxy_set */,
6198                                     NULL /* humongous_proxy_set */,
6199                                     false /* par */);
6200   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6201   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6202 }
6203 
6204 // This routine is similar to the above but does not record
6205 // any policy statistics or update free lists; we are abandoning
6206 // the current incremental collection set in preparation of a
6207 // full collection. After the full GC we will start to build up
6208 // the incremental collection set again.
6209 // This is only called when we're doing a full collection
6210 // and is immediately followed by the tearing down of the young list.
6211 
6212 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6213   HeapRegion* cur = cs_head;
6214 
6215   while (cur != NULL) {
6216     HeapRegion* next = cur->next_in_collection_set();
6217     assert(cur->in_collection_set(), "bad CS");
6218     cur->set_next_in_collection_set(NULL);
6219     cur->set_in_collection_set(false);
6220     cur->set_young_index_in_cset(-1);
6221     cur = next;
6222   }
6223 }
6224 
6225 void G1CollectedHeap::set_free_regions_coming() {
6226   if (G1ConcRegionFreeingVerbose) {
6227     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6228                            "setting free regions coming");
6229   }
6230 
6231   assert(!free_regions_coming(), "pre-condition");
6232   _free_regions_coming = true;
6233 }
6234 
6235 void G1CollectedHeap::reset_free_regions_coming() {
6236   assert(free_regions_coming(), "pre-condition");
6237 
6238   {
6239     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6240     _free_regions_coming = false;
6241     SecondaryFreeList_lock->notify_all();
6242   }
6243 
6244   if (G1ConcRegionFreeingVerbose) {
6245     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6246                            "reset free regions coming");
6247   }
6248 }
6249 
6250 void G1CollectedHeap::wait_while_free_regions_coming() {
6251   // Most of the time we won't have to wait, so let's do a quick test
6252   // first before we take the lock.
6253   if (!free_regions_coming()) {
6254     return;
6255   }
6256 
6257   if (G1ConcRegionFreeingVerbose) {
6258     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6259                            "waiting for free regions");
6260   }
6261 
6262   {
6263     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6264     while (free_regions_coming()) {
6265       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6266     }
6267   }
6268 
6269   if (G1ConcRegionFreeingVerbose) {
6270     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6271                            "done waiting for free regions");
6272   }
6273 }
6274 
6275 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6276   assert(heap_lock_held_for_gc(),
6277               "the heap lock should already be held by or for this thread");
6278   _young_list->push_region(hr);
6279 }
6280 
6281 class NoYoungRegionsClosure: public HeapRegionClosure {
6282 private:
6283   bool _success;
6284 public:
6285   NoYoungRegionsClosure() : _success(true) { }
6286   bool doHeapRegion(HeapRegion* r) {
6287     if (r->is_young()) {
6288       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6289                              r->bottom(), r->end());
6290       _success = false;
6291     }
6292     return false;
6293   }
6294   bool success() { return _success; }
6295 };
6296 
6297 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6298   bool ret = _young_list->check_list_empty(check_sample);
6299 
6300   if (check_heap) {
6301     NoYoungRegionsClosure closure;
6302     heap_region_iterate(&closure);
6303     ret = ret && closure.success();
6304   }
6305 
6306   return ret;
6307 }
6308 
6309 class TearDownRegionSetsClosure : public HeapRegionClosure {
6310 private:
6311   OldRegionSet *_old_set;
6312 
6313 public:
6314   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6315 
6316   bool doHeapRegion(HeapRegion* r) {
6317     if (r->is_empty()) {
6318       // We ignore empty regions, we'll empty the free list afterwards
6319     } else if (r->is_young()) {
6320       // We ignore young regions, we'll empty the young list afterwards
6321     } else if (r->isHumongous()) {
6322       // We ignore humongous regions, we're not tearing down the
6323       // humongous region set
6324     } else {
6325       // The rest should be old
6326       _old_set->remove(r);
6327     }
6328     return false;
6329   }
6330 
6331   ~TearDownRegionSetsClosure() {
6332     assert(_old_set->is_empty(), "post-condition");
6333   }
6334 };
6335 
6336 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6337   assert_at_safepoint(true /* should_be_vm_thread */);
6338 
6339   if (!free_list_only) {
6340     TearDownRegionSetsClosure cl(&_old_set);
6341     heap_region_iterate(&cl);
6342 
6343     // Need to do this after the heap iteration to be able to
6344     // recognize the young regions and ignore them during the iteration.
6345     _young_list->empty_list();
6346   }
6347   _free_list.remove_all();
6348 }
6349 
6350 class RebuildRegionSetsClosure : public HeapRegionClosure {
6351 private:
6352   bool            _free_list_only;
6353   OldRegionSet*   _old_set;
6354   FreeRegionList* _free_list;
6355   size_t          _total_used;
6356 
6357 public:
6358   RebuildRegionSetsClosure(bool free_list_only,
6359                            OldRegionSet* old_set, FreeRegionList* free_list) :
6360     _free_list_only(free_list_only),
6361     _old_set(old_set), _free_list(free_list), _total_used(0) {
6362     assert(_free_list->is_empty(), "pre-condition");
6363     if (!free_list_only) {
6364       assert(_old_set->is_empty(), "pre-condition");
6365     }
6366   }
6367 
6368   bool doHeapRegion(HeapRegion* r) {
6369     if (r->continuesHumongous()) {
6370       return false;
6371     }
6372 
6373     if (r->is_empty()) {
6374       // Add free regions to the free list
6375       _free_list->add_as_tail(r);
6376     } else if (!_free_list_only) {
6377       assert(!r->is_young(), "we should not come across young regions");
6378 
6379       if (r->isHumongous()) {
6380         // We ignore humongous regions, we left the humongous set unchanged
6381       } else {
6382         // The rest should be old, add them to the old set
6383         _old_set->add(r);
6384       }
6385       _total_used += r->used();
6386     }
6387 
6388     return false;
6389   }
6390 
6391   size_t total_used() {
6392     return _total_used;
6393   }
6394 };
6395 
6396 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6397   assert_at_safepoint(true /* should_be_vm_thread */);
6398 
6399   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6400   heap_region_iterate(&cl);
6401 
6402   if (!free_list_only) {
6403     _summary_bytes_used = cl.total_used();
6404   }
6405   assert(_summary_bytes_used == recalculate_used(),
6406          err_msg("inconsistent _summary_bytes_used, "
6407                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6408                  _summary_bytes_used, recalculate_used()));
6409 }
6410 
6411 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6412   _refine_cte_cl->set_concurrent(concurrent);
6413 }
6414 
6415 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6416   HeapRegion* hr = heap_region_containing(p);
6417   if (hr == NULL) {
6418     return false;
6419   } else {
6420     return hr->is_in(p);
6421   }
6422 }
6423 
6424 // Methods for the mutator alloc region
6425 
6426 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6427                                                       bool force) {
6428   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6429   assert(!force || g1_policy()->can_expand_young_list(),
6430          "if force is true we should be able to expand the young list");
6431   bool young_list_full = g1_policy()->is_young_list_full();
6432   if (force || !young_list_full) {
6433     HeapRegion* new_alloc_region = new_region(word_size,
6434                                               false /* do_expand */);
6435     if (new_alloc_region != NULL) {
6436       set_region_short_lived_locked(new_alloc_region);
6437       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6438       return new_alloc_region;
6439     }
6440   }
6441   return NULL;
6442 }
6443 
6444 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6445                                                   size_t allocated_bytes) {
6446   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6447   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6448 
6449   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6450   _summary_bytes_used += allocated_bytes;
6451   _hr_printer.retire(alloc_region);
6452   // We update the eden sizes here, when the region is retired,
6453   // instead of when it's allocated, since this is the point that its
6454   // used space has been recored in _summary_bytes_used.
6455   g1mm()->update_eden_size();
6456 }
6457 
6458 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6459                                                     bool force) {
6460   return _g1h->new_mutator_alloc_region(word_size, force);
6461 }
6462 
6463 void G1CollectedHeap::set_par_threads() {
6464   // Don't change the number of workers.  Use the value previously set
6465   // in the workgroup.
6466   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6467   uint n_workers = workers()->active_workers();
6468   assert(UseDynamicNumberOfGCThreads ||
6469            n_workers == workers()->total_workers(),
6470       "Otherwise should be using the total number of workers");
6471   if (n_workers == 0) {
6472     assert(false, "Should have been set in prior evacuation pause.");
6473     n_workers = ParallelGCThreads;
6474     workers()->set_active_workers(n_workers);
6475   }
6476   set_par_threads(n_workers);
6477 }
6478 
6479 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6480                                        size_t allocated_bytes) {
6481   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6482 }
6483 
6484 // Methods for the GC alloc regions
6485 
6486 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6487                                                  uint count,
6488                                                  GCAllocPurpose ap) {
6489   assert(FreeList_lock->owned_by_self(), "pre-condition");
6490 
6491   if (count < g1_policy()->max_regions(ap)) {
6492     HeapRegion* new_alloc_region = new_region(word_size,
6493                                               true /* do_expand */);
6494     if (new_alloc_region != NULL) {
6495       // We really only need to do this for old regions given that we
6496       // should never scan survivors. But it doesn't hurt to do it
6497       // for survivors too.
6498       new_alloc_region->set_saved_mark();
6499       if (ap == GCAllocForSurvived) {
6500         new_alloc_region->set_survivor();
6501         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6502       } else {
6503         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6504       }
6505       bool during_im = g1_policy()->during_initial_mark_pause();
6506       new_alloc_region->note_start_of_copying(during_im);
6507       return new_alloc_region;
6508     } else {
6509       g1_policy()->note_alloc_region_limit_reached(ap);
6510     }
6511   }
6512   return NULL;
6513 }
6514 
6515 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6516                                              size_t allocated_bytes,
6517                                              GCAllocPurpose ap) {
6518   bool during_im = g1_policy()->during_initial_mark_pause();
6519   alloc_region->note_end_of_copying(during_im);
6520   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6521   if (ap == GCAllocForSurvived) {
6522     young_list()->add_survivor_region(alloc_region);
6523   } else {
6524     _old_set.add(alloc_region);
6525   }
6526   _hr_printer.retire(alloc_region);
6527 }
6528 
6529 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6530                                                        bool force) {
6531   assert(!force, "not supported for GC alloc regions");
6532   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6533 }
6534 
6535 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6536                                           size_t allocated_bytes) {
6537   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6538                                GCAllocForSurvived);
6539 }
6540 
6541 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6542                                                   bool force) {
6543   assert(!force, "not supported for GC alloc regions");
6544   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6545 }
6546 
6547 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6548                                      size_t allocated_bytes) {
6549   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6550                                GCAllocForTenured);
6551 }
6552 // Heap region set verification
6553 
6554 class VerifyRegionListsClosure : public HeapRegionClosure {
6555 private:
6556   FreeRegionList*     _free_list;
6557   OldRegionSet*       _old_set;
6558   HumongousRegionSet* _humongous_set;
6559   uint                _region_count;
6560 
6561 public:
6562   VerifyRegionListsClosure(OldRegionSet* old_set,
6563                            HumongousRegionSet* humongous_set,
6564                            FreeRegionList* free_list) :
6565     _old_set(old_set), _humongous_set(humongous_set),
6566     _free_list(free_list), _region_count(0) { }
6567 
6568   uint region_count() { return _region_count; }
6569 
6570   bool doHeapRegion(HeapRegion* hr) {
6571     _region_count += 1;
6572 
6573     if (hr->continuesHumongous()) {
6574       return false;
6575     }
6576 
6577     if (hr->is_young()) {
6578       // TODO
6579     } else if (hr->startsHumongous()) {
6580       _humongous_set->verify_next_region(hr);
6581     } else if (hr->is_empty()) {
6582       _free_list->verify_next_region(hr);
6583     } else {
6584       _old_set->verify_next_region(hr);
6585     }
6586     return false;
6587   }
6588 };
6589 
6590 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6591                                              HeapWord* bottom) {
6592   HeapWord* end = bottom + HeapRegion::GrainWords;
6593   MemRegion mr(bottom, end);
6594   assert(_g1_reserved.contains(mr), "invariant");
6595   // This might return NULL if the allocation fails
6596   return new HeapRegion(hrs_index, _bot_shared, mr);
6597 }
6598 
6599 void G1CollectedHeap::verify_region_sets() {
6600   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6601 
6602   // First, check the explicit lists.
6603   _free_list.verify();
6604   {
6605     // Given that a concurrent operation might be adding regions to
6606     // the secondary free list we have to take the lock before
6607     // verifying it.
6608     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6609     _secondary_free_list.verify();
6610   }
6611   _old_set.verify();
6612   _humongous_set.verify();
6613 
6614   // If a concurrent region freeing operation is in progress it will
6615   // be difficult to correctly attributed any free regions we come
6616   // across to the correct free list given that they might belong to
6617   // one of several (free_list, secondary_free_list, any local lists,
6618   // etc.). So, if that's the case we will skip the rest of the
6619   // verification operation. Alternatively, waiting for the concurrent
6620   // operation to complete will have a non-trivial effect on the GC's
6621   // operation (no concurrent operation will last longer than the
6622   // interval between two calls to verification) and it might hide
6623   // any issues that we would like to catch during testing.
6624   if (free_regions_coming()) {
6625     return;
6626   }
6627 
6628   // Make sure we append the secondary_free_list on the free_list so
6629   // that all free regions we will come across can be safely
6630   // attributed to the free_list.
6631   append_secondary_free_list_if_not_empty_with_lock();
6632 
6633   // Finally, make sure that the region accounting in the lists is
6634   // consistent with what we see in the heap.
6635   _old_set.verify_start();
6636   _humongous_set.verify_start();
6637   _free_list.verify_start();
6638 
6639   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6640   heap_region_iterate(&cl);
6641 
6642   _old_set.verify_end();
6643   _humongous_set.verify_end();
6644   _free_list.verify_end();
6645 }
6646 
6647 // Optimized nmethod scanning
6648 
6649 class RegisterNMethodOopClosure: public OopClosure {
6650   G1CollectedHeap* _g1h;
6651   nmethod* _nm;
6652 
6653   template <class T> void do_oop_work(T* p) {
6654     T heap_oop = oopDesc::load_heap_oop(p);
6655     if (!oopDesc::is_null(heap_oop)) {
6656       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6657       HeapRegion* hr = _g1h->heap_region_containing(obj);
6658       assert(!hr->isHumongous(), "code root in humongous region?");
6659 
6660       // HeapRegion::add_strong_code_root() avoids adding duplicate
6661       // entries but having duplicates is  OK since we "mark" nmethods
6662       // as visited when we scan the strong code root lists during the GC.
6663       hr->add_strong_code_root(_nm);
6664       assert(hr->rem_set()->strong_code_roots_list_contains(_nm), "add failed?");
6665     }
6666   }
6667 
6668 public:
6669   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6670     _g1h(g1h), _nm(nm) {}
6671 
6672   void do_oop(oop* p)       { do_oop_work(p); }
6673   void do_oop(narrowOop* p) { do_oop_work(p); }
6674 };
6675 
6676 class UnregisterNMethodOopClosure: public OopClosure {
6677   G1CollectedHeap* _g1h;
6678   nmethod* _nm;
6679 
6680   template <class T> void do_oop_work(T* p) {
6681     T heap_oop = oopDesc::load_heap_oop(p);
6682     if (!oopDesc::is_null(heap_oop)) {
6683       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6684       HeapRegion* hr = _g1h->heap_region_containing(obj);
6685       assert(!hr->isHumongous(), "code root in humongous region?");
6686       hr->remove_strong_code_root(_nm);
6687       assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), "remove failed?");
6688     }
6689   }
6690 
6691 public:
6692   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6693     _g1h(g1h), _nm(nm) {}
6694 
6695   void do_oop(oop* p)       { do_oop_work(p); }
6696   void do_oop(narrowOop* p) { do_oop_work(p); }
6697 };
6698 
6699 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6700   CollectedHeap::register_nmethod(nm);
6701 
6702   guarantee(nm != NULL, "sanity");
6703   RegisterNMethodOopClosure reg_cl(this, nm);
6704   nm->oops_do(&reg_cl);
6705 }
6706 
6707 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6708   CollectedHeap::unregister_nmethod(nm);
6709 
6710   guarantee(nm != NULL, "sanity");
6711   UnregisterNMethodOopClosure reg_cl(this, nm);
6712   nm->oops_do(&reg_cl, true);
6713 }
6714 
6715 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6716 public:
6717   bool doHeapRegion(HeapRegion *hr) {
6718     assert(!hr->isHumongous(), "humongous region in collection set?");
6719     hr->migrate_strong_code_roots();
6720     return false;
6721   }
6722 };
6723 
6724 void G1CollectedHeap::migrate_strong_code_roots() {
6725   MigrateCodeRootsHeapRegionClosure cl;
6726   double migrate_start = os::elapsedTime();
6727   collection_set_iterate(&cl);
6728   double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6729   g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6730 }
6731 
6732 // Mark all the code roots that point into regions *not* in the
6733 // collection set.
6734 //
6735 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6736 // walking the the code roots lists of regions not in the collection
6737 // set. Suppose we have an nmethod (M) that points to objects in two
6738 // separate regions - one in the collection set (R1) and one not (R2).
6739 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6740 // nmethod M when walking the code roots for R1. When we come to scan
6741 // the code roots for R2, we would see that M is already marked and it
6742 // would be skipped and the objects in R2 that are referenced from M
6743 // would not be evacuated.
6744 
6745 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6746 
6747   class MarkStrongCodeRootOopClosure: public OopClosure {
6748     ConcurrentMark* _cm;
6749     HeapRegion* _hr;
6750     uint _worker_id;
6751 
6752     template <class T> void do_oop_work(T* p) {
6753       T heap_oop = oopDesc::load_heap_oop(p);
6754       if (!oopDesc::is_null(heap_oop)) {
6755         oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6756         // Only mark objects in the region (which is assumed
6757         // to be not in the collection set).
6758         if (_hr->is_in(obj)) {
6759           _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6760         }
6761       }
6762     }
6763 
6764   public:
6765     MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6766       _cm(cm), _hr(hr), _worker_id(worker_id) {
6767       assert(!_hr->in_collection_set(), "sanity");
6768     }
6769 
6770     void do_oop(narrowOop* p) { do_oop_work(p); }
6771     void do_oop(oop* p)       { do_oop_work(p); }
6772   };
6773 
6774   MarkStrongCodeRootOopClosure _oop_cl;
6775 
6776 public:
6777   MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6778     _oop_cl(cm, hr, worker_id) {}
6779 
6780   void do_code_blob(CodeBlob* cb) {
6781     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6782     if (nm != NULL) {
6783       nm->oops_do(&_oop_cl);
6784     }
6785   }
6786 };
6787 
6788 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6789   G1CollectedHeap* _g1h;
6790   uint _worker_id;
6791 
6792 public:
6793   MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6794     _g1h(g1h), _worker_id(worker_id) {}
6795 
6796   bool doHeapRegion(HeapRegion *hr) {
6797     HeapRegionRemSet* hrrs = hr->rem_set();
6798     if (hr->isHumongous()) {
6799       // Code roots should never be attached to a humongous region
6800       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
6801       return false;
6802     }
6803 
6804     if (hr->in_collection_set()) {
6805       // Don't mark code roots into regions in the collection set here.
6806       // They will be marked when we scan them.
6807       return false;
6808     }
6809 
6810     MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6811     hr->strong_code_roots_do(&cb_cl);
6812     return false;
6813   }
6814 };
6815 
6816 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6817   MarkStrongCodeRootsHRClosure cl(this, worker_id);
6818   if (G1CollectedHeap::use_parallel_gc_threads()) {
6819     heap_region_par_iterate_chunked(&cl,
6820                                     worker_id,
6821                                     workers()->active_workers(),
6822                                     HeapRegion::ParMarkRootClaimValue);
6823   } else {
6824     heap_region_iterate(&cl);
6825   }
6826 }
6827 
6828 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6829   G1CollectedHeap* _g1h;
6830 
6831 public:
6832   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6833     _g1h(g1h) {}
6834 
6835   void do_code_blob(CodeBlob* cb) {
6836     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6837     if (nm == NULL) {
6838       return;
6839     }
6840 
6841     if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6842       _g1h->register_nmethod(nm);
6843     }
6844   }
6845 };
6846 
6847 void G1CollectedHeap::rebuild_strong_code_roots() {
6848   RebuildStrongCodeRootClosure blob_cl(this);
6849   CodeCache::blobs_do(&blob_cl);
6850 }