1 /*
   2  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #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/generationSpec.hpp"
  54 #include "memory/iterator.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 #include "utilities/ticks.hpp"
  60 
  61 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  62 
  63 // turn it on so that the contents of the young list (scan-only /
  64 // to-be-collected) are printed at "strategic" points before / during
  65 // / after the collection --- this is useful for debugging
  66 #define YOUNG_LIST_VERBOSE 0
  67 // CURRENT STATUS
  68 // This file is under construction.  Search for "FIXME".
  69 
  70 // INVARIANTS/NOTES
  71 //
  72 // All allocation activity covered by the G1CollectedHeap interface is
  73 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  74 // and allocate_new_tlab, which are the "entry" points to the
  75 // allocation code from the rest of the JVM.  (Note that this does not
  76 // apply to TLAB allocation, which is not part of this interface: it
  77 // is done by clients of this interface.)
  78 
  79 // Notes on implementation of parallelism in different tasks.
  80 //
  81 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  82 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  83 // It does use run_task() which sets _n_workers in the task.
  84 // G1ParTask executes g1_process_strong_roots() ->
  85 // SharedHeap::process_strong_roots() which calls eventually to
  86 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  87 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  88 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  89 //
  90 
  91 // Local to this file.
  92 
  93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  94   SuspendibleThreadSet* _sts;
  95   G1RemSet* _g1rs;
  96   ConcurrentG1Refine* _cg1r;
  97   bool _concurrent;
  98 public:
  99   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
 100                               G1RemSet* g1rs,
 101                               ConcurrentG1Refine* cg1r) :
 102     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
 103   {}
 104   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 105     bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
 106     // This path is executed by the concurrent refine or mutator threads,
 107     // concurrently, and so we do not care if card_ptr contains references
 108     // that point into the collection set.
 109     assert(!oops_into_cset, "should be");
 110 
 111     if (_concurrent && _sts->should_yield()) {
 112       // Caller will actually yield.
 113       return false;
 114     }
 115     // Otherwise, we finished successfully; return true.
 116     return true;
 117   }
 118   void set_concurrent(bool b) { _concurrent = b; }
 119 };
 120 
 121 
 122 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 123   int _calls;
 124   G1CollectedHeap* _g1h;
 125   CardTableModRefBS* _ctbs;
 126   int _histo[256];
 127 public:
 128   ClearLoggedCardTableEntryClosure() :
 129     _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
 130   {
 131     for (int i = 0; i < 256; i++) _histo[i] = 0;
 132   }
 133   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 134     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 135       _calls++;
 136       unsigned char* ujb = (unsigned char*)card_ptr;
 137       int ind = (int)(*ujb);
 138       _histo[ind]++;
 139       *card_ptr = -1;
 140     }
 141     return true;
 142   }
 143   int calls() { return _calls; }
 144   void print_histo() {
 145     gclog_or_tty->print_cr("Card table value histogram:");
 146     for (int i = 0; i < 256; i++) {
 147       if (_histo[i] != 0) {
 148         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 149       }
 150     }
 151   }
 152 };
 153 
 154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 155   int _calls;
 156   G1CollectedHeap* _g1h;
 157   CardTableModRefBS* _ctbs;
 158 public:
 159   RedirtyLoggedCardTableEntryClosure() :
 160     _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
 161 
 162   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 163     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 164       _calls++;
 165       *card_ptr = 0;
 166     }
 167     return true;
 168   }
 169   int calls() { return _calls; }
 170 };
 171 
 172 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 173 public:
 174   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 175     *card_ptr = CardTableModRefBS::dirty_card_val();
 176     return true;
 177   }
 178 };
 179 
 180 YoungList::YoungList(G1CollectedHeap* g1h) :
 181     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 182     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 183   guarantee(check_list_empty(false), "just making sure...");
 184 }
 185 
 186 void YoungList::push_region(HeapRegion *hr) {
 187   assert(!hr->is_young(), "should not already be young");
 188   assert(hr->get_next_young_region() == NULL, "cause it should!");
 189 
 190   hr->set_next_young_region(_head);
 191   _head = hr;
 192 
 193   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 194   ++_length;
 195 }
 196 
 197 void YoungList::add_survivor_region(HeapRegion* hr) {
 198   assert(hr->is_survivor(), "should be flagged as survivor region");
 199   assert(hr->get_next_young_region() == NULL, "cause it should!");
 200 
 201   hr->set_next_young_region(_survivor_head);
 202   if (_survivor_head == NULL) {
 203     _survivor_tail = hr;
 204   }
 205   _survivor_head = hr;
 206   ++_survivor_length;
 207 }
 208 
 209 void YoungList::empty_list(HeapRegion* list) {
 210   while (list != NULL) {
 211     HeapRegion* next = list->get_next_young_region();
 212     list->set_next_young_region(NULL);
 213     list->uninstall_surv_rate_group();
 214     list->set_not_young();
 215     list = next;
 216   }
 217 }
 218 
 219 void YoungList::empty_list() {
 220   assert(check_list_well_formed(), "young list should be well formed");
 221 
 222   empty_list(_head);
 223   _head = NULL;
 224   _length = 0;
 225 
 226   empty_list(_survivor_head);
 227   _survivor_head = NULL;
 228   _survivor_tail = NULL;
 229   _survivor_length = 0;
 230 
 231   _last_sampled_rs_lengths = 0;
 232 
 233   assert(check_list_empty(false), "just making sure...");
 234 }
 235 
 236 bool YoungList::check_list_well_formed() {
 237   bool ret = true;
 238 
 239   uint length = 0;
 240   HeapRegion* curr = _head;
 241   HeapRegion* last = NULL;
 242   while (curr != NULL) {
 243     if (!curr->is_young()) {
 244       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 245                              "incorrectly tagged (y: %d, surv: %d)",
 246                              curr->bottom(), curr->end(),
 247                              curr->is_young(), curr->is_survivor());
 248       ret = false;
 249     }
 250     ++length;
 251     last = curr;
 252     curr = curr->get_next_young_region();
 253   }
 254   ret = ret && (length == _length);
 255 
 256   if (!ret) {
 257     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 258     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 259                            length, _length);
 260   }
 261 
 262   return ret;
 263 }
 264 
 265 bool YoungList::check_list_empty(bool check_sample) {
 266   bool ret = true;
 267 
 268   if (_length != 0) {
 269     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 270                   _length);
 271     ret = false;
 272   }
 273   if (check_sample && _last_sampled_rs_lengths != 0) {
 274     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 275     ret = false;
 276   }
 277   if (_head != NULL) {
 278     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 279     ret = false;
 280   }
 281   if (!ret) {
 282     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 283   }
 284 
 285   return ret;
 286 }
 287 
 288 void
 289 YoungList::rs_length_sampling_init() {
 290   _sampled_rs_lengths = 0;
 291   _curr               = _head;
 292 }
 293 
 294 bool
 295 YoungList::rs_length_sampling_more() {
 296   return _curr != NULL;
 297 }
 298 
 299 void
 300 YoungList::rs_length_sampling_next() {
 301   assert( _curr != NULL, "invariant" );
 302   size_t rs_length = _curr->rem_set()->occupied();
 303 
 304   _sampled_rs_lengths += rs_length;
 305 
 306   // The current region may not yet have been added to the
 307   // incremental collection set (it gets added when it is
 308   // retired as the current allocation region).
 309   if (_curr->in_collection_set()) {
 310     // Update the collection set policy information for this region
 311     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 312   }
 313 
 314   _curr = _curr->get_next_young_region();
 315   if (_curr == NULL) {
 316     _last_sampled_rs_lengths = _sampled_rs_lengths;
 317     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 318   }
 319 }
 320 
 321 void
 322 YoungList::reset_auxilary_lists() {
 323   guarantee( is_empty(), "young list should be empty" );
 324   assert(check_list_well_formed(), "young list should be well formed");
 325 
 326   // Add survivor regions to SurvRateGroup.
 327   _g1h->g1_policy()->note_start_adding_survivor_regions();
 328   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 329 
 330   int young_index_in_cset = 0;
 331   for (HeapRegion* curr = _survivor_head;
 332        curr != NULL;
 333        curr = curr->get_next_young_region()) {
 334     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 335 
 336     // The region is a non-empty survivor so let's add it to
 337     // the incremental collection set for the next evacuation
 338     // pause.
 339     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 340     young_index_in_cset += 1;
 341   }
 342   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 343   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 344 
 345   _head   = _survivor_head;
 346   _length = _survivor_length;
 347   if (_survivor_head != NULL) {
 348     assert(_survivor_tail != NULL, "cause it shouldn't be");
 349     assert(_survivor_length > 0, "invariant");
 350     _survivor_tail->set_next_young_region(NULL);
 351   }
 352 
 353   // Don't clear the survivor list handles until the start of
 354   // the next evacuation pause - we need it in order to re-tag
 355   // the survivor regions from this evacuation pause as 'young'
 356   // at the start of the next.
 357 
 358   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 359 
 360   assert(check_list_well_formed(), "young list should be well formed");
 361 }
 362 
 363 void YoungList::print() {
 364   HeapRegion* lists[] = {_head,   _survivor_head};
 365   const char* names[] = {"YOUNG", "SURVIVOR"};
 366 
 367   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 368     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 369     HeapRegion *curr = lists[list];
 370     if (curr == NULL)
 371       gclog_or_tty->print_cr("  empty");
 372     while (curr != NULL) {
 373       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 374                              HR_FORMAT_PARAMS(curr),
 375                              curr->prev_top_at_mark_start(),
 376                              curr->next_top_at_mark_start(),
 377                              curr->age_in_surv_rate_group_cond());
 378       curr = curr->get_next_young_region();
 379     }
 380   }
 381 
 382   gclog_or_tty->print_cr("");
 383 }
 384 
 385 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 386 {
 387   // Claim the right to put the region on the dirty cards region list
 388   // by installing a self pointer.
 389   HeapRegion* next = hr->get_next_dirty_cards_region();
 390   if (next == NULL) {
 391     HeapRegion* res = (HeapRegion*)
 392       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 393                           NULL);
 394     if (res == NULL) {
 395       HeapRegion* head;
 396       do {
 397         // Put the region to the dirty cards region list.
 398         head = _dirty_cards_region_list;
 399         next = (HeapRegion*)
 400           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 401         if (next == head) {
 402           assert(hr->get_next_dirty_cards_region() == hr,
 403                  "hr->get_next_dirty_cards_region() != hr");
 404           if (next == NULL) {
 405             // The last region in the list points to itself.
 406             hr->set_next_dirty_cards_region(hr);
 407           } else {
 408             hr->set_next_dirty_cards_region(next);
 409           }
 410         }
 411       } while (next != head);
 412     }
 413   }
 414 }
 415 
 416 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 417 {
 418   HeapRegion* head;
 419   HeapRegion* hr;
 420   do {
 421     head = _dirty_cards_region_list;
 422     if (head == NULL) {
 423       return NULL;
 424     }
 425     HeapRegion* new_head = head->get_next_dirty_cards_region();
 426     if (head == new_head) {
 427       // The last region.
 428       new_head = NULL;
 429     }
 430     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 431                                           head);
 432   } while (hr != head);
 433   assert(hr != NULL, "invariant");
 434   hr->set_next_dirty_cards_region(NULL);
 435   return hr;
 436 }
 437 
 438 void G1CollectedHeap::stop_conc_gc_threads() {
 439   _cg1r->stop();
 440   _cmThread->stop();
 441 }
 442 
 443 #ifdef ASSERT
 444 // A region is added to the collection set as it is retired
 445 // so an address p can point to a region which will be in the
 446 // collection set but has not yet been retired.  This method
 447 // therefore is only accurate during a GC pause after all
 448 // regions have been retired.  It is used for debugging
 449 // to check if an nmethod has references to objects that can
 450 // be move during a partial collection.  Though it can be
 451 // inaccurate, it is sufficient for G1 because the conservative
 452 // implementation of is_scavengable() for G1 will indicate that
 453 // all nmethods must be scanned during a partial collection.
 454 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 455   HeapRegion* hr = heap_region_containing(p);
 456   return hr != NULL && hr->in_collection_set();
 457 }
 458 #endif
 459 
 460 // Returns true if the reference points to an object that
 461 // can move in an incremental collection.
 462 bool G1CollectedHeap::is_scavengable(const void* p) {
 463   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 464   G1CollectorPolicy* g1p = g1h->g1_policy();
 465   HeapRegion* hr = heap_region_containing(p);
 466   if (hr == NULL) {
 467      // null
 468      assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
 469      return false;
 470   } else {
 471     return !hr->isHumongous();
 472   }
 473 }
 474 
 475 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 476   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 477   CardTableModRefBS* ct_bs = g1_barrier_set();
 478 
 479   // Count the dirty cards at the start.
 480   CountNonCleanMemRegionClosure count1(this);
 481   ct_bs->mod_card_iterate(&count1);
 482   int orig_count = count1.n();
 483 
 484   // First clear the logged cards.
 485   ClearLoggedCardTableEntryClosure clear;
 486   dcqs.set_closure(&clear);
 487   dcqs.apply_closure_to_all_completed_buffers();
 488   dcqs.iterate_closure_all_threads(false);
 489   clear.print_histo();
 490 
 491   // Now ensure that there's no dirty cards.
 492   CountNonCleanMemRegionClosure count2(this);
 493   ct_bs->mod_card_iterate(&count2);
 494   if (count2.n() != 0) {
 495     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 496                            count2.n(), orig_count);
 497   }
 498   guarantee(count2.n() == 0, "Card table should be clean.");
 499 
 500   RedirtyLoggedCardTableEntryClosure redirty;
 501   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 502   dcqs.apply_closure_to_all_completed_buffers();
 503   dcqs.iterate_closure_all_threads(false);
 504   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 505                          clear.calls(), orig_count);
 506   guarantee(redirty.calls() == clear.calls(),
 507             "Or else mechanism is broken.");
 508 
 509   CountNonCleanMemRegionClosure count3(this);
 510   ct_bs->mod_card_iterate(&count3);
 511   if (count3.n() != orig_count) {
 512     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 513                            orig_count, count3.n());
 514     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 515   }
 516 
 517   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 518 }
 519 
 520 // Private class members.
 521 
 522 G1CollectedHeap* G1CollectedHeap::_g1h;
 523 
 524 // Private methods.
 525 
 526 HeapRegion*
 527 G1CollectedHeap::new_region_try_secondary_free_list() {
 528   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 529   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 530     if (!_secondary_free_list.is_empty()) {
 531       if (G1ConcRegionFreeingVerbose) {
 532         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 533                                "secondary_free_list has %u entries",
 534                                _secondary_free_list.length());
 535       }
 536       // It looks as if there are free regions available on the
 537       // secondary_free_list. Let's move them to the free_list and try
 538       // again to allocate from it.
 539       append_secondary_free_list();
 540 
 541       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 542              "empty we should have moved at least one entry to the free_list");
 543       HeapRegion* res = _free_list.remove_head();
 544       if (G1ConcRegionFreeingVerbose) {
 545         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 546                                "allocated "HR_FORMAT" from secondary_free_list",
 547                                HR_FORMAT_PARAMS(res));
 548       }
 549       return res;
 550     }
 551 
 552     // Wait here until we get notified either when (a) there are no
 553     // more free regions coming or (b) some regions have been moved on
 554     // the secondary_free_list.
 555     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 556   }
 557 
 558   if (G1ConcRegionFreeingVerbose) {
 559     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 560                            "could not allocate from secondary_free_list");
 561   }
 562   return NULL;
 563 }
 564 
 565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 566   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 567          "the only time we use this to allocate a humongous region is "
 568          "when we are allocating a single humongous region");
 569 
 570   HeapRegion* res;
 571   if (G1StressConcRegionFreeing) {
 572     if (!_secondary_free_list.is_empty()) {
 573       if (G1ConcRegionFreeingVerbose) {
 574         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 575                                "forced to look at the secondary_free_list");
 576       }
 577       res = new_region_try_secondary_free_list();
 578       if (res != NULL) {
 579         return res;
 580       }
 581     }
 582   }
 583   res = _free_list.remove_head_or_null();
 584   if (res == NULL) {
 585     if (G1ConcRegionFreeingVerbose) {
 586       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 587                              "res == NULL, trying the secondary_free_list");
 588     }
 589     res = new_region_try_secondary_free_list();
 590   }
 591   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 592     // Currently, only attempts to allocate GC alloc regions set
 593     // do_expand to true. So, we should only reach here during a
 594     // safepoint. If this assumption changes we might have to
 595     // reconsider the use of _expand_heap_after_alloc_failure.
 596     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 597 
 598     ergo_verbose1(ErgoHeapSizing,
 599                   "attempt heap expansion",
 600                   ergo_format_reason("region allocation request failed")
 601                   ergo_format_byte("allocation request"),
 602                   word_size * HeapWordSize);
 603     if (expand(word_size * HeapWordSize)) {
 604       // Given that expand() succeeded in expanding the heap, and we
 605       // always expand the heap by an amount aligned to the heap
 606       // region size, the free list should in theory not be empty. So
 607       // it would probably be OK to use remove_head(). But the extra
 608       // check for NULL is unlikely to be a performance issue here (we
 609       // just expanded the heap!) so let's just be conservative and
 610       // use remove_head_or_null().
 611       res = _free_list.remove_head_or_null();
 612     } else {
 613       _expand_heap_after_alloc_failure = false;
 614     }
 615   }
 616   return res;
 617 }
 618 
 619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 620                                                         size_t word_size) {
 621   assert(isHumongous(word_size), "word_size should be humongous");
 622   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 623 
 624   uint first = G1_NULL_HRS_INDEX;
 625   if (num_regions == 1) {
 626     // Only one region to allocate, no need to go through the slower
 627     // path. The caller will attempt the expansion if this fails, so
 628     // let's not try to expand here too.
 629     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 630     if (hr != NULL) {
 631       first = hr->hrs_index();
 632     } else {
 633       first = G1_NULL_HRS_INDEX;
 634     }
 635   } else {
 636     // We can't allocate humongous regions while cleanupComplete() is
 637     // running, since some of the regions we find to be empty might not
 638     // yet be added to the free list and it is not straightforward to
 639     // know which list they are on so that we can remove them. Note
 640     // that we only need to do this if we need to allocate more than
 641     // one region to satisfy the current humongous allocation
 642     // request. If we are only allocating one region we use the common
 643     // region allocation code (see above).
 644     wait_while_free_regions_coming();
 645     append_secondary_free_list_if_not_empty_with_lock();
 646 
 647     if (free_regions() >= num_regions) {
 648       first = _hrs.find_contiguous(num_regions);
 649       if (first != G1_NULL_HRS_INDEX) {
 650         for (uint i = first; i < first + num_regions; ++i) {
 651           HeapRegion* hr = region_at(i);
 652           assert(hr->is_empty(), "sanity");
 653           assert(is_on_master_free_list(hr), "sanity");
 654           hr->set_pending_removal(true);
 655         }
 656         _free_list.remove_all_pending(num_regions);
 657       }
 658     }
 659   }
 660   return first;
 661 }
 662 
 663 HeapWord*
 664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 665                                                            uint num_regions,
 666                                                            size_t word_size) {
 667   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 668   assert(isHumongous(word_size), "word_size should be humongous");
 669   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 670 
 671   // Index of last region in the series + 1.
 672   uint last = first + num_regions;
 673 
 674   // We need to initialize the region(s) we just discovered. This is
 675   // a bit tricky given that it can happen concurrently with
 676   // refinement threads refining cards on these regions and
 677   // potentially wanting to refine the BOT as they are scanning
 678   // those cards (this can happen shortly after a cleanup; see CR
 679   // 6991377). So we have to set up the region(s) carefully and in
 680   // a specific order.
 681 
 682   // The word size sum of all the regions we will allocate.
 683   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 684   assert(word_size <= word_size_sum, "sanity");
 685 
 686   // This will be the "starts humongous" region.
 687   HeapRegion* first_hr = region_at(first);
 688   // The header of the new object will be placed at the bottom of
 689   // the first region.
 690   HeapWord* new_obj = first_hr->bottom();
 691   // This will be the new end of the first region in the series that
 692   // should also match the end of the last region in the series.
 693   HeapWord* new_end = new_obj + word_size_sum;
 694   // This will be the new top of the first region that will reflect
 695   // this allocation.
 696   HeapWord* new_top = new_obj + word_size;
 697 
 698   // First, we need to zero the header of the space that we will be
 699   // allocating. When we update top further down, some refinement
 700   // threads might try to scan the region. By zeroing the header we
 701   // ensure that any thread that will try to scan the region will
 702   // come across the zero klass word and bail out.
 703   //
 704   // NOTE: It would not have been correct to have used
 705   // CollectedHeap::fill_with_object() and make the space look like
 706   // an int array. The thread that is doing the allocation will
 707   // later update the object header to a potentially different array
 708   // type and, for a very short period of time, the klass and length
 709   // fields will be inconsistent. This could cause a refinement
 710   // thread to calculate the object size incorrectly.
 711   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 712 
 713   // We will set up the first region as "starts humongous". This
 714   // will also update the BOT covering all the regions to reflect
 715   // that there is a single object that starts at the bottom of the
 716   // first region.
 717   first_hr->set_startsHumongous(new_top, new_end);
 718 
 719   // Then, if there are any, we will set up the "continues
 720   // humongous" regions.
 721   HeapRegion* hr = NULL;
 722   for (uint i = first + 1; i < last; ++i) {
 723     hr = region_at(i);
 724     hr->set_continuesHumongous(first_hr);
 725   }
 726   // If we have "continues humongous" regions (hr != NULL), then the
 727   // end of the last one should match new_end.
 728   assert(hr == NULL || hr->end() == new_end, "sanity");
 729 
 730   // Up to this point no concurrent thread would have been able to
 731   // do any scanning on any region in this series. All the top
 732   // fields still point to bottom, so the intersection between
 733   // [bottom,top] and [card_start,card_end] will be empty. Before we
 734   // update the top fields, we'll do a storestore to make sure that
 735   // no thread sees the update to top before the zeroing of the
 736   // object header and the BOT initialization.
 737   OrderAccess::storestore();
 738 
 739   // Now that the BOT and the object header have been initialized,
 740   // we can update top of the "starts humongous" region.
 741   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 742          "new_top should be in this region");
 743   first_hr->set_top(new_top);
 744   if (_hr_printer.is_active()) {
 745     HeapWord* bottom = first_hr->bottom();
 746     HeapWord* end = first_hr->orig_end();
 747     if ((first + 1) == last) {
 748       // the series has a single humongous region
 749       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 750     } else {
 751       // the series has more than one humongous regions
 752       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 753     }
 754   }
 755 
 756   // Now, we will update the top fields of the "continues humongous"
 757   // regions. The reason we need to do this is that, otherwise,
 758   // these regions would look empty and this will confuse parts of
 759   // G1. For example, the code that looks for a consecutive number
 760   // of empty regions will consider them empty and try to
 761   // re-allocate them. We can extend is_empty() to also include
 762   // !continuesHumongous(), but it is easier to just update the top
 763   // fields here. The way we set top for all regions (i.e., top ==
 764   // end for all regions but the last one, top == new_top for the
 765   // last one) is actually used when we will free up the humongous
 766   // region in free_humongous_region().
 767   hr = NULL;
 768   for (uint i = first + 1; i < last; ++i) {
 769     hr = region_at(i);
 770     if ((i + 1) == last) {
 771       // last continues humongous region
 772       assert(hr->bottom() < new_top && new_top <= hr->end(),
 773              "new_top should fall on this region");
 774       hr->set_top(new_top);
 775       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 776     } else {
 777       // not last one
 778       assert(new_top > hr->end(), "new_top should be above this region");
 779       hr->set_top(hr->end());
 780       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 781     }
 782   }
 783   // If we have continues humongous regions (hr != NULL), then the
 784   // end of the last one should match new_end and its top should
 785   // match new_top.
 786   assert(hr == NULL ||
 787          (hr->end() == new_end && hr->top() == new_top), "sanity");
 788 
 789   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 790   _summary_bytes_used += first_hr->used();
 791   _humongous_set.add(first_hr);
 792 
 793   return new_obj;
 794 }
 795 
 796 // If could fit into free regions w/o expansion, try.
 797 // Otherwise, if can expand, do so.
 798 // Otherwise, if using ex regions might help, try with ex given back.
 799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 800   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 801 
 802   verify_region_sets_optional();
 803 
 804   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 805   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 806   uint x_num = expansion_regions();
 807   uint fs = _hrs.free_suffix();
 808   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 809   if (first == G1_NULL_HRS_INDEX) {
 810     // The only thing we can do now is attempt expansion.
 811     if (fs + x_num >= num_regions) {
 812       // If the number of regions we're trying to allocate for this
 813       // object is at most the number of regions in the free suffix,
 814       // then the call to humongous_obj_allocate_find_first() above
 815       // should have succeeded and we wouldn't be here.
 816       //
 817       // We should only be trying to expand when the free suffix is
 818       // not sufficient for the object _and_ we have some expansion
 819       // room available.
 820       assert(num_regions > fs, "earlier allocation should have succeeded");
 821 
 822       ergo_verbose1(ErgoHeapSizing,
 823                     "attempt heap expansion",
 824                     ergo_format_reason("humongous allocation request failed")
 825                     ergo_format_byte("allocation request"),
 826                     word_size * HeapWordSize);
 827       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 828         // Even though the heap was expanded, it might not have
 829         // reached the desired size. So, we cannot assume that the
 830         // allocation will succeed.
 831         first = humongous_obj_allocate_find_first(num_regions, word_size);
 832       }
 833     }
 834   }
 835 
 836   HeapWord* result = NULL;
 837   if (first != G1_NULL_HRS_INDEX) {
 838     result =
 839       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 840     assert(result != NULL, "it should always return a valid result");
 841 
 842     // A successful humongous object allocation changes the used space
 843     // information of the old generation so we need to recalculate the
 844     // sizes and update the jstat counters here.
 845     g1mm()->update_sizes();
 846   }
 847 
 848   verify_region_sets_optional();
 849 
 850   return result;
 851 }
 852 
 853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 854   assert_heap_not_locked_and_not_at_safepoint();
 855   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 856 
 857   unsigned int dummy_gc_count_before;
 858   int dummy_gclocker_retry_count = 0;
 859   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 860 }
 861 
 862 HeapWord*
 863 G1CollectedHeap::mem_allocate(size_t word_size,
 864                               bool*  gc_overhead_limit_was_exceeded) {
 865   assert_heap_not_locked_and_not_at_safepoint();
 866 
 867   // Loop until the allocation is satisfied, or unsatisfied after GC.
 868   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 869     unsigned int gc_count_before;
 870 
 871     HeapWord* result = NULL;
 872     if (!isHumongous(word_size)) {
 873       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 874     } else {
 875       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 876     }
 877     if (result != NULL) {
 878       return result;
 879     }
 880 
 881     // Create the garbage collection operation...
 882     VM_G1CollectForAllocation op(gc_count_before, word_size);
 883     // ...and get the VM thread to execute it.
 884     VMThread::execute(&op);
 885 
 886     if (op.prologue_succeeded() && op.pause_succeeded()) {
 887       // If the operation was successful we'll return the result even
 888       // if it is NULL. If the allocation attempt failed immediately
 889       // after a Full GC, it's unlikely we'll be able to allocate now.
 890       HeapWord* result = op.result();
 891       if (result != NULL && !isHumongous(word_size)) {
 892         // Allocations that take place on VM operations do not do any
 893         // card dirtying and we have to do it here. We only have to do
 894         // this for non-humongous allocations, though.
 895         dirty_young_block(result, word_size);
 896       }
 897       return result;
 898     } else {
 899       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 900         return NULL;
 901       }
 902       assert(op.result() == NULL,
 903              "the result should be NULL if the VM op did not succeed");
 904     }
 905 
 906     // Give a warning if we seem to be looping forever.
 907     if ((QueuedAllocationWarningCount > 0) &&
 908         (try_count % QueuedAllocationWarningCount == 0)) {
 909       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 910     }
 911   }
 912 
 913   ShouldNotReachHere();
 914   return NULL;
 915 }
 916 
 917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 918                                            unsigned int *gc_count_before_ret,
 919                                            int* gclocker_retry_count_ret) {
 920   // Make sure you read the note in attempt_allocation_humongous().
 921 
 922   assert_heap_not_locked_and_not_at_safepoint();
 923   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 924          "be called for humongous allocation requests");
 925 
 926   // We should only get here after the first-level allocation attempt
 927   // (attempt_allocation()) failed to allocate.
 928 
 929   // We will loop until a) we manage to successfully perform the
 930   // allocation or b) we successfully schedule a collection which
 931   // fails to perform the allocation. b) is the only case when we'll
 932   // return NULL.
 933   HeapWord* result = NULL;
 934   for (int try_count = 1; /* we'll return */; try_count += 1) {
 935     bool should_try_gc;
 936     unsigned int gc_count_before;
 937 
 938     {
 939       MutexLockerEx x(Heap_lock);
 940 
 941       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 942                                                       false /* bot_updates */);
 943       if (result != NULL) {
 944         return result;
 945       }
 946 
 947       // If we reach here, attempt_allocation_locked() above failed to
 948       // allocate a new region. So the mutator alloc region should be NULL.
 949       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 950 
 951       if (GC_locker::is_active_and_needs_gc()) {
 952         if (g1_policy()->can_expand_young_list()) {
 953           // No need for an ergo verbose message here,
 954           // can_expand_young_list() does this when it returns true.
 955           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 956                                                       false /* bot_updates */);
 957           if (result != NULL) {
 958             return result;
 959           }
 960         }
 961         should_try_gc = false;
 962       } else {
 963         // The GCLocker may not be active but the GCLocker initiated
 964         // GC may not yet have been performed (GCLocker::needs_gc()
 965         // returns true). In this case we do not try this GC and
 966         // wait until the GCLocker initiated GC is performed, and
 967         // then retry the allocation.
 968         if (GC_locker::needs_gc()) {
 969           should_try_gc = false;
 970         } else {
 971           // Read the GC count while still holding the Heap_lock.
 972           gc_count_before = total_collections();
 973           should_try_gc = true;
 974         }
 975       }
 976     }
 977 
 978     if (should_try_gc) {
 979       bool succeeded;
 980       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 981           GCCause::_g1_inc_collection_pause);
 982       if (result != NULL) {
 983         assert(succeeded, "only way to get back a non-NULL result");
 984         return result;
 985       }
 986 
 987       if (succeeded) {
 988         // If we get here we successfully scheduled a collection which
 989         // failed to allocate. No point in trying to allocate
 990         // further. We'll just return NULL.
 991         MutexLockerEx x(Heap_lock);
 992         *gc_count_before_ret = total_collections();
 993         return NULL;
 994       }
 995     } else {
 996       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 997         MutexLockerEx x(Heap_lock);
 998         *gc_count_before_ret = total_collections();
 999         return NULL;
1000       }
1001       // The GCLocker is either active or the GCLocker initiated
1002       // GC has not yet been performed. Stall until it is and
1003       // then retry the allocation.
1004       GC_locker::stall_until_clear();
1005       (*gclocker_retry_count_ret) += 1;
1006     }
1007 
1008     // We can reach here if we were unsuccessful in scheduling a
1009     // collection (because another thread beat us to it) or if we were
1010     // stalled due to the GC locker. In either can we should retry the
1011     // allocation attempt in case another thread successfully
1012     // performed a collection and reclaimed enough space. We do the
1013     // first attempt (without holding the Heap_lock) here and the
1014     // follow-on attempt will be at the start of the next loop
1015     // iteration (after taking the Heap_lock).
1016     result = _mutator_alloc_region.attempt_allocation(word_size,
1017                                                       false /* bot_updates */);
1018     if (result != NULL) {
1019       return result;
1020     }
1021 
1022     // Give a warning if we seem to be looping forever.
1023     if ((QueuedAllocationWarningCount > 0) &&
1024         (try_count % QueuedAllocationWarningCount == 0)) {
1025       warning("G1CollectedHeap::attempt_allocation_slow() "
1026               "retries %d times", try_count);
1027     }
1028   }
1029 
1030   ShouldNotReachHere();
1031   return NULL;
1032 }
1033 
1034 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1035                                           unsigned int * gc_count_before_ret,
1036                                           int* gclocker_retry_count_ret) {
1037   // The structure of this method has a lot of similarities to
1038   // attempt_allocation_slow(). The reason these two were not merged
1039   // into a single one is that such a method would require several "if
1040   // allocation is not humongous do this, otherwise do that"
1041   // conditional paths which would obscure its flow. In fact, an early
1042   // version of this code did use a unified method which was harder to
1043   // follow and, as a result, it had subtle bugs that were hard to
1044   // track down. So keeping these two methods separate allows each to
1045   // be more readable. It will be good to keep these two in sync as
1046   // much as possible.
1047 
1048   assert_heap_not_locked_and_not_at_safepoint();
1049   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1050          "should only be called for humongous allocations");
1051 
1052   // Humongous objects can exhaust the heap quickly, so we should check if we
1053   // need to start a marking cycle at each humongous object allocation. We do
1054   // the check before we do the actual allocation. The reason for doing it
1055   // before the allocation is that we avoid having to keep track of the newly
1056   // allocated memory while we do a GC.
1057   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1058                                            word_size)) {
1059     collect(GCCause::_g1_humongous_allocation);
1060   }
1061 
1062   // We will loop until a) we manage to successfully perform the
1063   // allocation or b) we successfully schedule a collection which
1064   // fails to perform the allocation. b) is the only case when we'll
1065   // return NULL.
1066   HeapWord* result = NULL;
1067   for (int try_count = 1; /* we'll return */; try_count += 1) {
1068     bool should_try_gc;
1069     unsigned int gc_count_before;
1070 
1071     {
1072       MutexLockerEx x(Heap_lock);
1073 
1074       // Given that humongous objects are not allocated in young
1075       // regions, we'll first try to do the allocation without doing a
1076       // collection hoping that there's enough space in the heap.
1077       result = humongous_obj_allocate(word_size);
1078       if (result != NULL) {
1079         return result;
1080       }
1081 
1082       if (GC_locker::is_active_and_needs_gc()) {
1083         should_try_gc = false;
1084       } else {
1085          // The GCLocker may not be active but the GCLocker initiated
1086         // GC may not yet have been performed (GCLocker::needs_gc()
1087         // returns true). In this case we do not try this GC and
1088         // wait until the GCLocker initiated GC is performed, and
1089         // then retry the allocation.
1090         if (GC_locker::needs_gc()) {
1091           should_try_gc = false;
1092         } else {
1093           // Read the GC count while still holding the Heap_lock.
1094           gc_count_before = total_collections();
1095           should_try_gc = true;
1096         }
1097       }
1098     }
1099 
1100     if (should_try_gc) {
1101       // If we failed to allocate the humongous object, we should try to
1102       // do a collection pause (if we're allowed) in case it reclaims
1103       // enough space for the allocation to succeed after the pause.
1104 
1105       bool succeeded;
1106       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1107           GCCause::_g1_humongous_allocation);
1108       if (result != NULL) {
1109         assert(succeeded, "only way to get back a non-NULL result");
1110         return result;
1111       }
1112 
1113       if (succeeded) {
1114         // If we get here we successfully scheduled a collection which
1115         // failed to allocate. No point in trying to allocate
1116         // further. We'll just return NULL.
1117         MutexLockerEx x(Heap_lock);
1118         *gc_count_before_ret = total_collections();
1119         return NULL;
1120       }
1121     } else {
1122       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1123         MutexLockerEx x(Heap_lock);
1124         *gc_count_before_ret = total_collections();
1125         return NULL;
1126       }
1127       // The GCLocker is either active or the GCLocker initiated
1128       // GC has not yet been performed. Stall until it is and
1129       // then retry the allocation.
1130       GC_locker::stall_until_clear();
1131       (*gclocker_retry_count_ret) += 1;
1132     }
1133 
1134     // We can reach here if we were unsuccessful in scheduling a
1135     // collection (because another thread beat us to it) or if we were
1136     // stalled due to the GC locker. In either can we should retry the
1137     // allocation attempt in case another thread successfully
1138     // performed a collection and reclaimed enough space.  Give a
1139     // warning if we seem to be looping forever.
1140 
1141     if ((QueuedAllocationWarningCount > 0) &&
1142         (try_count % QueuedAllocationWarningCount == 0)) {
1143       warning("G1CollectedHeap::attempt_allocation_humongous() "
1144               "retries %d times", try_count);
1145     }
1146   }
1147 
1148   ShouldNotReachHere();
1149   return NULL;
1150 }
1151 
1152 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1153                                        bool expect_null_mutator_alloc_region) {
1154   assert_at_safepoint(true /* should_be_vm_thread */);
1155   assert(_mutator_alloc_region.get() == NULL ||
1156                                              !expect_null_mutator_alloc_region,
1157          "the current alloc region was unexpectedly found to be non-NULL");
1158 
1159   if (!isHumongous(word_size)) {
1160     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1161                                                       false /* bot_updates */);
1162   } else {
1163     HeapWord* result = humongous_obj_allocate(word_size);
1164     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1165       g1_policy()->set_initiate_conc_mark_if_possible();
1166     }
1167     return result;
1168   }
1169 
1170   ShouldNotReachHere();
1171 }
1172 
1173 class PostMCRemSetClearClosure: public HeapRegionClosure {
1174   G1CollectedHeap* _g1h;
1175   ModRefBarrierSet* _mr_bs;
1176 public:
1177   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1178     _g1h(g1h), _mr_bs(mr_bs) {}
1179 
1180   bool doHeapRegion(HeapRegion* r) {
1181     HeapRegionRemSet* hrrs = r->rem_set();
1182 
1183     if (r->continuesHumongous()) {
1184       // We'll assert that the strong code root list and RSet is empty
1185       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1186       assert(hrrs->occupied() == 0, "RSet should be empty");
1187       return false;
1188     }
1189 
1190     _g1h->reset_gc_time_stamps(r);
1191     hrrs->clear();
1192     // You might think here that we could clear just the cards
1193     // corresponding to the used region.  But no: if we leave a dirty card
1194     // in a region we might allocate into, then it would prevent that card
1195     // from being enqueued, and cause it to be missed.
1196     // Re: the performance cost: we shouldn't be doing full GC anyway!
1197     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1198 
1199     return false;
1200   }
1201 };
1202 
1203 void G1CollectedHeap::clear_rsets_post_compaction() {
1204   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1205   heap_region_iterate(&rs_clear);
1206 }
1207 
1208 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1209   G1CollectedHeap*   _g1h;
1210   UpdateRSOopClosure _cl;
1211   int                _worker_i;
1212 public:
1213   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1214     _cl(g1->g1_rem_set(), worker_i),
1215     _worker_i(worker_i),
1216     _g1h(g1)
1217   { }
1218 
1219   bool doHeapRegion(HeapRegion* r) {
1220     if (!r->continuesHumongous()) {
1221       _cl.set_from(r);
1222       r->oop_iterate(&_cl);
1223     }
1224     return false;
1225   }
1226 };
1227 
1228 class ParRebuildRSTask: public AbstractGangTask {
1229   G1CollectedHeap* _g1;
1230 public:
1231   ParRebuildRSTask(G1CollectedHeap* g1)
1232     : AbstractGangTask("ParRebuildRSTask"),
1233       _g1(g1)
1234   { }
1235 
1236   void work(uint worker_id) {
1237     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1238     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1239                                           _g1->workers()->active_workers(),
1240                                          HeapRegion::RebuildRSClaimValue);
1241   }
1242 };
1243 
1244 class PostCompactionPrinterClosure: public HeapRegionClosure {
1245 private:
1246   G1HRPrinter* _hr_printer;
1247 public:
1248   bool doHeapRegion(HeapRegion* hr) {
1249     assert(!hr->is_young(), "not expecting to find young regions");
1250     // We only generate output for non-empty regions.
1251     if (!hr->is_empty()) {
1252       if (!hr->isHumongous()) {
1253         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1254       } else if (hr->startsHumongous()) {
1255         if (hr->region_num() == 1) {
1256           // single humongous region
1257           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1258         } else {
1259           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1260         }
1261       } else {
1262         assert(hr->continuesHumongous(), "only way to get here");
1263         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1264       }
1265     }
1266     return false;
1267   }
1268 
1269   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1270     : _hr_printer(hr_printer) { }
1271 };
1272 
1273 void G1CollectedHeap::print_hrs_post_compaction() {
1274   PostCompactionPrinterClosure cl(hr_printer());
1275   heap_region_iterate(&cl);
1276 }
1277 
1278 bool G1CollectedHeap::do_collection(bool explicit_gc,
1279                                     bool clear_all_soft_refs,
1280                                     size_t word_size) {
1281   assert_at_safepoint(true /* should_be_vm_thread */);
1282 
1283   if (GC_locker::check_active_before_gc()) {
1284     return false;
1285   }
1286 
1287   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1288   gc_timer->register_gc_start();
1289 
1290   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1291   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1292 
1293   SvcGCMarker sgcm(SvcGCMarker::FULL);
1294   ResourceMark rm;
1295 
1296   print_heap_before_gc();
1297   trace_heap_before_gc(gc_tracer);
1298 
1299   size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1300 
1301   HRSPhaseSetter x(HRSPhaseFullGC);
1302   verify_region_sets_optional();
1303 
1304   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1305                            collector_policy()->should_clear_all_soft_refs();
1306 
1307   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1308 
1309   {
1310     IsGCActiveMark x;
1311 
1312     // Timing
1313     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1314     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1315     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1316 
1317     {
1318       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1319       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1320       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1321 
1322       double start = os::elapsedTime();
1323       g1_policy()->record_full_collection_start();
1324 
1325       // Note: When we have a more flexible GC logging framework that
1326       // allows us to add optional attributes to a GC log record we
1327       // could consider timing and reporting how long we wait in the
1328       // following two methods.
1329       wait_while_free_regions_coming();
1330       // If we start the compaction before the CM threads finish
1331       // scanning the root regions we might trip them over as we'll
1332       // be moving objects / updating references. So let's wait until
1333       // they are done. By telling them to abort, they should complete
1334       // early.
1335       _cm->root_regions()->abort();
1336       _cm->root_regions()->wait_until_scan_finished();
1337       append_secondary_free_list_if_not_empty_with_lock();
1338 
1339       gc_prologue(true);
1340       increment_total_collections(true /* full gc */);
1341       increment_old_marking_cycles_started();
1342 
1343       assert(used() == recalculate_used(), "Should be equal");
1344 
1345       verify_before_gc();
1346 
1347       pre_full_gc_dump(gc_timer);
1348 
1349       COMPILER2_PRESENT(DerivedPointerTable::clear());
1350 
1351       // Disable discovery and empty the discovered lists
1352       // for the CM ref processor.
1353       ref_processor_cm()->disable_discovery();
1354       ref_processor_cm()->abandon_partial_discovery();
1355       ref_processor_cm()->verify_no_references_recorded();
1356 
1357       // Abandon current iterations of concurrent marking and concurrent
1358       // refinement, if any are in progress. We have to do this before
1359       // wait_until_scan_finished() below.
1360       concurrent_mark()->abort();
1361 
1362       // Make sure we'll choose a new allocation region afterwards.
1363       release_mutator_alloc_region();
1364       abandon_gc_alloc_regions();
1365       g1_rem_set()->cleanupHRRS();
1366 
1367       // We should call this after we retire any currently active alloc
1368       // regions so that all the ALLOC / RETIRE events are generated
1369       // before the start GC event.
1370       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1371 
1372       // We may have added regions to the current incremental collection
1373       // set between the last GC or pause and now. We need to clear the
1374       // incremental collection set and then start rebuilding it afresh
1375       // after this full GC.
1376       abandon_collection_set(g1_policy()->inc_cset_head());
1377       g1_policy()->clear_incremental_cset();
1378       g1_policy()->stop_incremental_cset_building();
1379 
1380       tear_down_region_sets(false /* free_list_only */);
1381       g1_policy()->set_gcs_are_young(true);
1382 
1383       // See the comments in g1CollectedHeap.hpp and
1384       // G1CollectedHeap::ref_processing_init() about
1385       // how reference processing currently works in G1.
1386 
1387       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1388       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1389 
1390       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1391       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1392 
1393       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1394       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1395 
1396       // Do collection work
1397       {
1398         HandleMark hm;  // Discard invalid handles created during gc
1399         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1400       }
1401 
1402       assert(free_regions() == 0, "we should not have added any free regions");
1403       rebuild_region_sets(false /* free_list_only */);
1404 
1405       // Enqueue any discovered reference objects that have
1406       // not been removed from the discovered lists.
1407       ref_processor_stw()->enqueue_discovered_references();
1408 
1409       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1410 
1411       MemoryService::track_memory_usage();
1412 
1413       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1414       ref_processor_stw()->verify_no_references_recorded();
1415 
1416       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1417       ClassLoaderDataGraph::purge();
1418       MetaspaceAux::verify_metrics();
1419 
1420       // Note: since we've just done a full GC, concurrent
1421       // marking is no longer active. Therefore we need not
1422       // re-enable reference discovery for the CM ref processor.
1423       // That will be done at the start of the next marking cycle.
1424       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1425       ref_processor_cm()->verify_no_references_recorded();
1426 
1427       reset_gc_time_stamp();
1428       // Since everything potentially moved, we will clear all remembered
1429       // sets, and clear all cards.  Later we will rebuild remembered
1430       // sets. We will also reset the GC time stamps of the regions.
1431       clear_rsets_post_compaction();
1432       check_gc_time_stamps();
1433 
1434       // Resize the heap if necessary.
1435       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1436 
1437       if (_hr_printer.is_active()) {
1438         // We should do this after we potentially resize the heap so
1439         // that all the COMMIT / UNCOMMIT events are generated before
1440         // the end GC event.
1441 
1442         print_hrs_post_compaction();
1443         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1444       }
1445 
1446       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1447       if (hot_card_cache->use_cache()) {
1448         hot_card_cache->reset_card_counts();
1449         hot_card_cache->reset_hot_cache();
1450       }
1451 
1452       // Rebuild remembered sets of all regions.
1453       if (G1CollectedHeap::use_parallel_gc_threads()) {
1454         uint n_workers =
1455           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1456                                                   workers()->active_workers(),
1457                                                   Threads::number_of_non_daemon_threads());
1458         assert(UseDynamicNumberOfGCThreads ||
1459                n_workers == workers()->total_workers(),
1460                "If not dynamic should be using all the  workers");
1461         workers()->set_active_workers(n_workers);
1462         // Set parallel threads in the heap (_n_par_threads) only
1463         // before a parallel phase and always reset it to 0 after
1464         // the phase so that the number of parallel threads does
1465         // no get carried forward to a serial phase where there
1466         // may be code that is "possibly_parallel".
1467         set_par_threads(n_workers);
1468 
1469         ParRebuildRSTask rebuild_rs_task(this);
1470         assert(check_heap_region_claim_values(
1471                HeapRegion::InitialClaimValue), "sanity check");
1472         assert(UseDynamicNumberOfGCThreads ||
1473                workers()->active_workers() == workers()->total_workers(),
1474                "Unless dynamic should use total workers");
1475         // Use the most recent number of  active workers
1476         assert(workers()->active_workers() > 0,
1477                "Active workers not properly set");
1478         set_par_threads(workers()->active_workers());
1479         workers()->run_task(&rebuild_rs_task);
1480         set_par_threads(0);
1481         assert(check_heap_region_claim_values(
1482                HeapRegion::RebuildRSClaimValue), "sanity check");
1483         reset_heap_region_claim_values();
1484       } else {
1485         RebuildRSOutOfRegionClosure rebuild_rs(this);
1486         heap_region_iterate(&rebuild_rs);
1487       }
1488 
1489       // Rebuild the strong code root lists for each region
1490       rebuild_strong_code_roots();
1491 
1492       if (true) { // FIXME
1493         MetaspaceGC::compute_new_size();
1494       }
1495 
1496 #ifdef TRACESPINNING
1497       ParallelTaskTerminator::print_termination_counts();
1498 #endif
1499 
1500       // Discard all rset updates
1501       JavaThread::dirty_card_queue_set().abandon_logs();
1502       assert(!G1DeferredRSUpdate
1503              || (G1DeferredRSUpdate &&
1504                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1505 
1506       _young_list->reset_sampled_info();
1507       // At this point there should be no regions in the
1508       // entire heap tagged as young.
1509       assert(check_young_list_empty(true /* check_heap */),
1510              "young list should be empty at this point");
1511 
1512       // Update the number of full collections that have been completed.
1513       increment_old_marking_cycles_completed(false /* concurrent */);
1514 
1515       _hrs.verify_optional();
1516       verify_region_sets_optional();
1517 
1518       verify_after_gc();
1519 
1520       // Start a new incremental collection set for the next pause
1521       assert(g1_policy()->collection_set() == NULL, "must be");
1522       g1_policy()->start_incremental_cset_building();
1523 
1524       // Clear the _cset_fast_test bitmap in anticipation of adding
1525       // regions to the incremental collection set for the next
1526       // evacuation pause.
1527       clear_cset_fast_test();
1528 
1529       init_mutator_alloc_region();
1530 
1531       double end = os::elapsedTime();
1532       g1_policy()->record_full_collection_end();
1533 
1534       if (G1Log::fine()) {
1535         g1_policy()->print_heap_transition();
1536       }
1537 
1538       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1539       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1540       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1541       // before any GC notifications are raised.
1542       g1mm()->update_sizes();
1543 
1544       gc_epilogue(true);
1545     }
1546 
1547     if (G1Log::finer()) {
1548       g1_policy()->print_detailed_heap_transition(true /* full */);
1549     }
1550 
1551     print_heap_after_gc();
1552     trace_heap_after_gc(gc_tracer);
1553 
1554     post_full_gc_dump(gc_timer);
1555 
1556     gc_timer->register_gc_end();
1557     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1558   }
1559 
1560   return true;
1561 }
1562 
1563 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1564   // do_collection() will return whether it succeeded in performing
1565   // the GC. Currently, there is no facility on the
1566   // do_full_collection() API to notify the caller than the collection
1567   // did not succeed (e.g., because it was locked out by the GC
1568   // locker). So, right now, we'll ignore the return value.
1569   bool dummy = do_collection(true,                /* explicit_gc */
1570                              clear_all_soft_refs,
1571                              0                    /* word_size */);
1572 }
1573 
1574 // This code is mostly copied from TenuredGeneration.
1575 void
1576 G1CollectedHeap::
1577 resize_if_necessary_after_full_collection(size_t word_size) {
1578   // Include the current allocation, if any, and bytes that will be
1579   // pre-allocated to support collections, as "used".
1580   const size_t used_after_gc = used();
1581   const size_t capacity_after_gc = capacity();
1582   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1583 
1584   // This is enforced in arguments.cpp.
1585   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1586          "otherwise the code below doesn't make sense");
1587 
1588   // We don't have floating point command-line arguments
1589   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1590   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1591   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1592   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1593 
1594   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1595   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1596 
1597   // We have to be careful here as these two calculations can overflow
1598   // 32-bit size_t's.
1599   double used_after_gc_d = (double) used_after_gc;
1600   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1601   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1602 
1603   // Let's make sure that they are both under the max heap size, which
1604   // by default will make them fit into a size_t.
1605   double desired_capacity_upper_bound = (double) max_heap_size;
1606   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1607                                     desired_capacity_upper_bound);
1608   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1609                                     desired_capacity_upper_bound);
1610 
1611   // We can now safely turn them into size_t's.
1612   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1613   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1614 
1615   // This assert only makes sense here, before we adjust them
1616   // with respect to the min and max heap size.
1617   assert(minimum_desired_capacity <= maximum_desired_capacity,
1618          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1619                  "maximum_desired_capacity = "SIZE_FORMAT,
1620                  minimum_desired_capacity, maximum_desired_capacity));
1621 
1622   // Should not be greater than the heap max size. No need to adjust
1623   // it with respect to the heap min size as it's a lower bound (i.e.,
1624   // we'll try to make the capacity larger than it, not smaller).
1625   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1626   // Should not be less than the heap min size. No need to adjust it
1627   // with respect to the heap max size as it's an upper bound (i.e.,
1628   // we'll try to make the capacity smaller than it, not greater).
1629   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1630 
1631   if (capacity_after_gc < minimum_desired_capacity) {
1632     // Don't expand unless it's significant
1633     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1634     ergo_verbose4(ErgoHeapSizing,
1635                   "attempt heap expansion",
1636                   ergo_format_reason("capacity lower than "
1637                                      "min desired capacity after Full GC")
1638                   ergo_format_byte("capacity")
1639                   ergo_format_byte("occupancy")
1640                   ergo_format_byte_perc("min desired capacity"),
1641                   capacity_after_gc, used_after_gc,
1642                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1643     expand(expand_bytes);
1644 
1645     // No expansion, now see if we want to shrink
1646   } else if (capacity_after_gc > maximum_desired_capacity) {
1647     // Capacity too large, compute shrinking size
1648     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1649     ergo_verbose4(ErgoHeapSizing,
1650                   "attempt heap shrinking",
1651                   ergo_format_reason("capacity higher than "
1652                                      "max desired capacity after Full GC")
1653                   ergo_format_byte("capacity")
1654                   ergo_format_byte("occupancy")
1655                   ergo_format_byte_perc("max desired capacity"),
1656                   capacity_after_gc, used_after_gc,
1657                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1658     shrink(shrink_bytes);
1659   }
1660 }
1661 
1662 
1663 HeapWord*
1664 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1665                                            bool* succeeded) {
1666   assert_at_safepoint(true /* should_be_vm_thread */);
1667 
1668   *succeeded = true;
1669   // Let's attempt the allocation first.
1670   HeapWord* result =
1671     attempt_allocation_at_safepoint(word_size,
1672                                  false /* expect_null_mutator_alloc_region */);
1673   if (result != NULL) {
1674     assert(*succeeded, "sanity");
1675     return result;
1676   }
1677 
1678   // In a G1 heap, we're supposed to keep allocation from failing by
1679   // incremental pauses.  Therefore, at least for now, we'll favor
1680   // expansion over collection.  (This might change in the future if we can
1681   // do something smarter than full collection to satisfy a failed alloc.)
1682   result = expand_and_allocate(word_size);
1683   if (result != NULL) {
1684     assert(*succeeded, "sanity");
1685     return result;
1686   }
1687 
1688   // Expansion didn't work, we'll try to do a Full GC.
1689   bool gc_succeeded = do_collection(false, /* explicit_gc */
1690                                     false, /* clear_all_soft_refs */
1691                                     word_size);
1692   if (!gc_succeeded) {
1693     *succeeded = false;
1694     return NULL;
1695   }
1696 
1697   // Retry the allocation
1698   result = attempt_allocation_at_safepoint(word_size,
1699                                   true /* expect_null_mutator_alloc_region */);
1700   if (result != NULL) {
1701     assert(*succeeded, "sanity");
1702     return result;
1703   }
1704 
1705   // Then, try a Full GC that will collect all soft references.
1706   gc_succeeded = do_collection(false, /* explicit_gc */
1707                                true,  /* clear_all_soft_refs */
1708                                word_size);
1709   if (!gc_succeeded) {
1710     *succeeded = false;
1711     return NULL;
1712   }
1713 
1714   // Retry the allocation once more
1715   result = attempt_allocation_at_safepoint(word_size,
1716                                   true /* expect_null_mutator_alloc_region */);
1717   if (result != NULL) {
1718     assert(*succeeded, "sanity");
1719     return result;
1720   }
1721 
1722   assert(!collector_policy()->should_clear_all_soft_refs(),
1723          "Flag should have been handled and cleared prior to this point");
1724 
1725   // What else?  We might try synchronous finalization later.  If the total
1726   // space available is large enough for the allocation, then a more
1727   // complete compaction phase than we've tried so far might be
1728   // appropriate.
1729   assert(*succeeded, "sanity");
1730   return NULL;
1731 }
1732 
1733 // Attempting to expand the heap sufficiently
1734 // to support an allocation of the given "word_size".  If
1735 // successful, perform the allocation and return the address of the
1736 // allocated block, or else "NULL".
1737 
1738 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1739   assert_at_safepoint(true /* should_be_vm_thread */);
1740 
1741   verify_region_sets_optional();
1742 
1743   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1744   ergo_verbose1(ErgoHeapSizing,
1745                 "attempt heap expansion",
1746                 ergo_format_reason("allocation request failed")
1747                 ergo_format_byte("allocation request"),
1748                 word_size * HeapWordSize);
1749   if (expand(expand_bytes)) {
1750     _hrs.verify_optional();
1751     verify_region_sets_optional();
1752     return attempt_allocation_at_safepoint(word_size,
1753                                  false /* expect_null_mutator_alloc_region */);
1754   }
1755   return NULL;
1756 }
1757 
1758 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1759                                              HeapWord* new_end) {
1760   assert(old_end != new_end, "don't call this otherwise");
1761   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1762 
1763   // Update the committed mem region.
1764   _g1_committed.set_end(new_end);
1765   // Tell the card table about the update.
1766   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1767   // Tell the BOT about the update.
1768   _bot_shared->resize(_g1_committed.word_size());
1769   // Tell the hot card cache about the update
1770   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1771 }
1772 
1773 bool G1CollectedHeap::expand(size_t expand_bytes) {
1774   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1775   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1776                                        HeapRegion::GrainBytes);
1777   ergo_verbose2(ErgoHeapSizing,
1778                 "expand the heap",
1779                 ergo_format_byte("requested expansion amount")
1780                 ergo_format_byte("attempted expansion amount"),
1781                 expand_bytes, aligned_expand_bytes);
1782 
1783   if (_g1_storage.uncommitted_size() == 0) {
1784     ergo_verbose0(ErgoHeapSizing,
1785                       "did not expand the heap",
1786                       ergo_format_reason("heap already fully expanded"));
1787     return false;
1788   }
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 aligned_shrink_bytes =
1849     ReservedSpace::page_align_size_down(shrink_bytes);
1850   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1851                                          HeapRegion::GrainBytes);
1852   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1853 
1854   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1855   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1856   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1857 
1858   ergo_verbose3(ErgoHeapSizing,
1859                 "shrink the heap",
1860                 ergo_format_byte("requested shrinking amount")
1861                 ergo_format_byte("aligned shrinking amount")
1862                 ergo_format_byte("attempted shrinking amount"),
1863                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1864   if (num_regions_removed > 0) {
1865     _g1_storage.shrink_by(shrunk_bytes);
1866     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1867 
1868     if (_hr_printer.is_active()) {
1869       HeapWord* curr = old_end;
1870       while (curr > new_end) {
1871         HeapWord* curr_end = curr;
1872         curr -= HeapRegion::GrainWords;
1873         _hr_printer.uncommit(curr, curr_end);
1874       }
1875     }
1876 
1877     _expansion_regions += num_regions_removed;
1878     update_committed_space(old_end, new_end);
1879     HeapRegionRemSet::shrink_heap(n_regions());
1880     g1_policy()->record_new_heap_size(n_regions());
1881   } else {
1882     ergo_verbose0(ErgoHeapSizing,
1883                   "did not shrink the heap",
1884                   ergo_format_reason("heap shrinking operation failed"));
1885   }
1886 }
1887 
1888 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1889   verify_region_sets_optional();
1890 
1891   // We should only reach here at the end of a Full GC which means we
1892   // should not not be holding to any GC alloc regions. The method
1893   // below will make sure of that and do any remaining clean up.
1894   abandon_gc_alloc_regions();
1895 
1896   // Instead of tearing down / rebuilding the free lists here, we
1897   // could instead use the remove_all_pending() method on free_list to
1898   // remove only the ones that we need to remove.
1899   tear_down_region_sets(true /* free_list_only */);
1900   shrink_helper(shrink_bytes);
1901   rebuild_region_sets(true /* free_list_only */);
1902 
1903   _hrs.verify_optional();
1904   verify_region_sets_optional();
1905 }
1906 
1907 // Public methods.
1908 
1909 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1910 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1911 #endif // _MSC_VER
1912 
1913 
1914 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1915   SharedHeap(policy_),
1916   _g1_policy(policy_),
1917   _dirty_card_queue_set(false),
1918   _into_cset_dirty_card_queue_set(false),
1919   _is_alive_closure_cm(this),
1920   _is_alive_closure_stw(this),
1921   _ref_processor_cm(NULL),
1922   _ref_processor_stw(NULL),
1923   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1924   _bot_shared(NULL),
1925   _evac_failure_scan_stack(NULL),
1926   _mark_in_progress(false),
1927   _cg1r(NULL), _summary_bytes_used(0),
1928   _g1mm(NULL),
1929   _refine_cte_cl(NULL),
1930   _full_collection(false),
1931   _free_list("Master Free List"),
1932   _secondary_free_list("Secondary Free List"),
1933   _old_set("Old Set"),
1934   _humongous_set("Master Humongous Set"),
1935   _free_regions_coming(false),
1936   _young_list(new YoungList(this)),
1937   _gc_time_stamp(0),
1938   _retained_old_gc_alloc_region(NULL),
1939   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1940   _old_plab_stats(OldPLABSize, PLABWeight),
1941   _expand_heap_after_alloc_failure(true),
1942   _surviving_young_words(NULL),
1943   _old_marking_cycles_started(0),
1944   _old_marking_cycles_completed(0),
1945   _concurrent_cycle_started(false),
1946   _in_cset_fast_test(NULL),
1947   _in_cset_fast_test_base(NULL),
1948   _dirty_cards_region_list(NULL),
1949   _worker_cset_start_region(NULL),
1950   _worker_cset_start_region_time_stamp(NULL),
1951   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1952   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1953   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1954   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1955 
1956   _g1h = this;
1957   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1958     vm_exit_during_initialization("Failed necessary allocation.");
1959   }
1960 
1961   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1962 
1963   int n_queues = MAX2((int)ParallelGCThreads, 1);
1964   _task_queues = new RefToScanQueueSet(n_queues);
1965 
1966   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1967   assert(n_rem_sets > 0, "Invariant.");
1968 
1969   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1970   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1971   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1972 
1973   for (int i = 0; i < n_queues; i++) {
1974     RefToScanQueue* q = new RefToScanQueue();
1975     q->initialize();
1976     _task_queues->register_queue(i, q);
1977     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1978   }
1979   clear_cset_start_regions();
1980 
1981   // Initialize the G1EvacuationFailureALot counters and flags.
1982   NOT_PRODUCT(reset_evacuation_should_fail();)
1983 
1984   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1985 }
1986 
1987 jint G1CollectedHeap::initialize() {
1988   CollectedHeap::pre_initialize();
1989   os::enable_vtime();
1990 
1991   G1Log::init();
1992 
1993   // Necessary to satisfy locking discipline assertions.
1994 
1995   MutexLocker x(Heap_lock);
1996 
1997   // We have to initialize the printer before committing the heap, as
1998   // it will be used then.
1999   _hr_printer.set_active(G1PrintHeapRegions);
2000 
2001   // While there are no constraints in the GC code that HeapWordSize
2002   // be any particular value, there are multiple other areas in the
2003   // system which believe this to be true (e.g. oop->object_size in some
2004   // cases incorrectly returns the size in wordSize units rather than
2005   // HeapWordSize).
2006   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2007 
2008   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2009   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2010   size_t heap_alignment = collector_policy()->heap_alignment();
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   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2016 
2017   _cg1r = new ConcurrentG1Refine(this);
2018 
2019   // Reserve the maximum.
2020 
2021   // When compressed oops are enabled, the preferred heap base
2022   // is calculated by subtracting the requested size from the
2023   // 32Gb boundary and using the result as the base address for
2024   // heap reservation. If the requested size is not aligned to
2025   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2026   // into the ReservedHeapSpace constructor) then the actual
2027   // base of the reserved heap may end up differing from the
2028   // address that was requested (i.e. the preferred heap base).
2029   // If this happens then we could end up using a non-optimal
2030   // compressed oops mode.
2031 
2032   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2033                                                  heap_alignment);
2034 
2035   // It is important to do this in a way such that concurrent readers can't
2036   // temporarily think something is in the heap.  (I've actually seen this
2037   // happen in asserts: DLD.)
2038   _reserved.set_word_size(0);
2039   _reserved.set_start((HeapWord*)heap_rs.base());
2040   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2041 
2042   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2043 
2044   // Create the gen rem set (and barrier set) for the entire reserved region.
2045   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2046   set_barrier_set(rem_set()->bs());
2047   if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2048     vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2049     return JNI_ENOMEM;
2050   }
2051 
2052   // Also create a G1 rem set.
2053   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2054 
2055   // Carve out the G1 part of the heap.
2056 
2057   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2058   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2059                            g1_rs.size()/HeapWordSize);
2060 
2061   _g1_storage.initialize(g1_rs, 0);
2062   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2063   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2064                   (HeapWord*) _g1_reserved.end());
2065   assert(_hrs.max_length() == _expansion_regions,
2066          err_msg("max length: %u expansion regions: %u",
2067                  _hrs.max_length(), _expansion_regions));
2068 
2069   // Do later initialization work for concurrent refinement.
2070   _cg1r->init();
2071 
2072   // 6843694 - ensure that the maximum region index can fit
2073   // in the remembered set structures.
2074   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2075   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2076 
2077   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2078   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2079   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2080             "too many cards per region");
2081 
2082   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2083 
2084   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2085                                              heap_word_size(init_byte_size));
2086 
2087   _g1h = this;
2088 
2089   _in_cset_fast_test_length = max_regions();
2090   _in_cset_fast_test_base =
2091                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2092 
2093   // We're biasing _in_cset_fast_test to avoid subtracting the
2094   // beginning of the heap every time we want to index; basically
2095   // it's the same with what we do with the card table.
2096   _in_cset_fast_test = _in_cset_fast_test_base -
2097                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2098 
2099   // Clear the _cset_fast_test bitmap in anticipation of adding
2100   // regions to the incremental collection set for the first
2101   // evacuation pause.
2102   clear_cset_fast_test();
2103 
2104   // Create the ConcurrentMark data structure and thread.
2105   // (Must do this late, so that "max_regions" is defined.)
2106   _cm = new ConcurrentMark(this, heap_rs);
2107   if (_cm == NULL || !_cm->completed_initialization()) {
2108     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2109     return JNI_ENOMEM;
2110   }
2111   _cmThread = _cm->cmThread();
2112 
2113   // Initialize the from_card cache structure of HeapRegionRemSet.
2114   HeapRegionRemSet::init_heap(max_regions());
2115 
2116   // Now expand into the initial heap size.
2117   if (!expand(init_byte_size)) {
2118     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2119     return JNI_ENOMEM;
2120   }
2121 
2122   // Perform any initialization actions delegated to the policy.
2123   g1_policy()->init();
2124 
2125   _refine_cte_cl =
2126     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2127                                     g1_rem_set(),
2128                                     concurrent_g1_refine());
2129   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2130 
2131   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2132                                                SATB_Q_FL_lock,
2133                                                G1SATBProcessCompletedThreshold,
2134                                                Shared_SATB_Q_lock);
2135 
2136   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2137                                                 DirtyCardQ_FL_lock,
2138                                                 concurrent_g1_refine()->yellow_zone(),
2139                                                 concurrent_g1_refine()->red_zone(),
2140                                                 Shared_DirtyCardQ_lock);
2141 
2142   if (G1DeferredRSUpdate) {
2143     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2144                                       DirtyCardQ_FL_lock,
2145                                       -1, // never trigger processing
2146                                       -1, // no limit on length
2147                                       Shared_DirtyCardQ_lock,
2148                                       &JavaThread::dirty_card_queue_set());
2149   }
2150 
2151   // Initialize the card queue set used to hold cards containing
2152   // references into the collection set.
2153   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2154                                              DirtyCardQ_FL_lock,
2155                                              -1, // never trigger processing
2156                                              -1, // no limit on length
2157                                              Shared_DirtyCardQ_lock,
2158                                              &JavaThread::dirty_card_queue_set());
2159 
2160   // In case we're keeping closure specialization stats, initialize those
2161   // counts and that mechanism.
2162   SpecializationStats::clear();
2163 
2164   // Here we allocate the dummy full region that is required by the
2165   // G1AllocRegion class. If we don't pass an address in the reserved
2166   // space here, lots of asserts fire.
2167 
2168   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2169                                              _g1_reserved.start());
2170   // We'll re-use the same region whether the alloc region will
2171   // require BOT updates or not and, if it doesn't, then a non-young
2172   // region will complain that it cannot support allocations without
2173   // BOT updates. So we'll tag the dummy region as young to avoid that.
2174   dummy_region->set_young();
2175   // Make sure it's full.
2176   dummy_region->set_top(dummy_region->end());
2177   G1AllocRegion::setup(this, dummy_region);
2178 
2179   init_mutator_alloc_region();
2180 
2181   // Do create of the monitoring and management support so that
2182   // values in the heap have been properly initialized.
2183   _g1mm = new G1MonitoringSupport(this);
2184 
2185   return JNI_OK;
2186 }
2187 
2188 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2189   return HeapRegion::max_region_size();
2190 }
2191 
2192 void G1CollectedHeap::ref_processing_init() {
2193   // Reference processing in G1 currently works as follows:
2194   //
2195   // * There are two reference processor instances. One is
2196   //   used to record and process discovered references
2197   //   during concurrent marking; the other is used to
2198   //   record and process references during STW pauses
2199   //   (both full and incremental).
2200   // * Both ref processors need to 'span' the entire heap as
2201   //   the regions in the collection set may be dotted around.
2202   //
2203   // * For the concurrent marking ref processor:
2204   //   * Reference discovery is enabled at initial marking.
2205   //   * Reference discovery is disabled and the discovered
2206   //     references processed etc during remarking.
2207   //   * Reference discovery is MT (see below).
2208   //   * Reference discovery requires a barrier (see below).
2209   //   * Reference processing may or may not be MT
2210   //     (depending on the value of ParallelRefProcEnabled
2211   //     and ParallelGCThreads).
2212   //   * A full GC disables reference discovery by the CM
2213   //     ref processor and abandons any entries on it's
2214   //     discovered lists.
2215   //
2216   // * For the STW processor:
2217   //   * Non MT discovery is enabled at the start of a full GC.
2218   //   * Processing and enqueueing during a full GC is non-MT.
2219   //   * During a full GC, references are processed after marking.
2220   //
2221   //   * Discovery (may or may not be MT) is enabled at the start
2222   //     of an incremental evacuation pause.
2223   //   * References are processed near the end of a STW evacuation pause.
2224   //   * For both types of GC:
2225   //     * Discovery is atomic - i.e. not concurrent.
2226   //     * Reference discovery will not need a barrier.
2227 
2228   SharedHeap::ref_processing_init();
2229   MemRegion mr = reserved_region();
2230 
2231   // Concurrent Mark ref processor
2232   _ref_processor_cm =
2233     new ReferenceProcessor(mr,    // span
2234                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2235                                 // mt processing
2236                            (int) ParallelGCThreads,
2237                                 // degree of mt processing
2238                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2239                                 // mt discovery
2240                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2241                                 // degree of mt discovery
2242                            false,
2243                                 // Reference discovery is not atomic
2244                            &_is_alive_closure_cm,
2245                                 // is alive closure
2246                                 // (for efficiency/performance)
2247                            true);
2248                                 // Setting next fields of discovered
2249                                 // lists requires a barrier.
2250 
2251   // STW ref processor
2252   _ref_processor_stw =
2253     new ReferenceProcessor(mr,    // span
2254                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2255                                 // mt processing
2256                            MAX2((int)ParallelGCThreads, 1),
2257                                 // degree of mt processing
2258                            (ParallelGCThreads > 1),
2259                                 // mt discovery
2260                            MAX2((int)ParallelGCThreads, 1),
2261                                 // degree of mt discovery
2262                            true,
2263                                 // Reference discovery is atomic
2264                            &_is_alive_closure_stw,
2265                                 // is alive closure
2266                                 // (for efficiency/performance)
2267                            false);
2268                                 // Setting next fields of discovered
2269                                 // lists does not require a barrier.
2270 }
2271 
2272 size_t G1CollectedHeap::capacity() const {
2273   return _g1_committed.byte_size();
2274 }
2275 
2276 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2277   assert(!hr->continuesHumongous(), "pre-condition");
2278   hr->reset_gc_time_stamp();
2279   if (hr->startsHumongous()) {
2280     uint first_index = hr->hrs_index() + 1;
2281     uint last_index = hr->last_hc_index();
2282     for (uint i = first_index; i < last_index; i += 1) {
2283       HeapRegion* chr = region_at(i);
2284       assert(chr->continuesHumongous(), "sanity");
2285       chr->reset_gc_time_stamp();
2286     }
2287   }
2288 }
2289 
2290 #ifndef PRODUCT
2291 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2292 private:
2293   unsigned _gc_time_stamp;
2294   bool _failures;
2295 
2296 public:
2297   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2298     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2299 
2300   virtual bool doHeapRegion(HeapRegion* hr) {
2301     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2302     if (_gc_time_stamp != region_gc_time_stamp) {
2303       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2304                              "expected %d", HR_FORMAT_PARAMS(hr),
2305                              region_gc_time_stamp, _gc_time_stamp);
2306       _failures = true;
2307     }
2308     return false;
2309   }
2310 
2311   bool failures() { return _failures; }
2312 };
2313 
2314 void G1CollectedHeap::check_gc_time_stamps() {
2315   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2316   heap_region_iterate(&cl);
2317   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2318 }
2319 #endif // PRODUCT
2320 
2321 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2322                                                  DirtyCardQueue* into_cset_dcq,
2323                                                  bool concurrent,
2324                                                  int worker_i) {
2325   // Clean cards in the hot card cache
2326   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2327   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2328 
2329   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2330   int n_completed_buffers = 0;
2331   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2332     n_completed_buffers++;
2333   }
2334   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2335   dcqs.clear_n_completed_buffers();
2336   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2337 }
2338 
2339 
2340 // Computes the sum of the storage used by the various regions.
2341 
2342 size_t G1CollectedHeap::used() const {
2343   assert(Heap_lock->owner() != NULL,
2344          "Should be owned on this thread's behalf.");
2345   size_t result = _summary_bytes_used;
2346   // Read only once in case it is set to NULL concurrently
2347   HeapRegion* hr = _mutator_alloc_region.get();
2348   if (hr != NULL)
2349     result += hr->used();
2350   return result;
2351 }
2352 
2353 size_t G1CollectedHeap::used_unlocked() const {
2354   size_t result = _summary_bytes_used;
2355   return result;
2356 }
2357 
2358 class SumUsedClosure: public HeapRegionClosure {
2359   size_t _used;
2360 public:
2361   SumUsedClosure() : _used(0) {}
2362   bool doHeapRegion(HeapRegion* r) {
2363     if (!r->continuesHumongous()) {
2364       _used += r->used();
2365     }
2366     return false;
2367   }
2368   size_t result() { return _used; }
2369 };
2370 
2371 size_t G1CollectedHeap::recalculate_used() const {
2372   SumUsedClosure blk;
2373   heap_region_iterate(&blk);
2374   return blk.result();
2375 }
2376 
2377 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2378   switch (cause) {
2379     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2380     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2381     case GCCause::_g1_humongous_allocation: return true;
2382     default:                                return false;
2383   }
2384 }
2385 
2386 #ifndef PRODUCT
2387 void G1CollectedHeap::allocate_dummy_regions() {
2388   // Let's fill up most of the region
2389   size_t word_size = HeapRegion::GrainWords - 1024;
2390   // And as a result the region we'll allocate will be humongous.
2391   guarantee(isHumongous(word_size), "sanity");
2392 
2393   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2394     // Let's use the existing mechanism for the allocation
2395     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2396     if (dummy_obj != NULL) {
2397       MemRegion mr(dummy_obj, word_size);
2398       CollectedHeap::fill_with_object(mr);
2399     } else {
2400       // If we can't allocate once, we probably cannot allocate
2401       // again. Let's get out of the loop.
2402       break;
2403     }
2404   }
2405 }
2406 #endif // !PRODUCT
2407 
2408 void G1CollectedHeap::increment_old_marking_cycles_started() {
2409   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2410     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2411     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2412     _old_marking_cycles_started, _old_marking_cycles_completed));
2413 
2414   _old_marking_cycles_started++;
2415 }
2416 
2417 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2418   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2419 
2420   // We assume that if concurrent == true, then the caller is a
2421   // concurrent thread that was joined the Suspendible Thread
2422   // Set. If there's ever a cheap way to check this, we should add an
2423   // assert here.
2424 
2425   // Given that this method is called at the end of a Full GC or of a
2426   // concurrent cycle, and those can be nested (i.e., a Full GC can
2427   // interrupt a concurrent cycle), the number of full collections
2428   // completed should be either one (in the case where there was no
2429   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2430   // behind the number of full collections started.
2431 
2432   // This is the case for the inner caller, i.e. a Full GC.
2433   assert(concurrent ||
2434          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2435          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2436          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2437                  "is inconsistent with _old_marking_cycles_completed = %u",
2438                  _old_marking_cycles_started, _old_marking_cycles_completed));
2439 
2440   // This is the case for the outer caller, i.e. the concurrent cycle.
2441   assert(!concurrent ||
2442          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2443          err_msg("for outer caller (concurrent cycle): "
2444                  "_old_marking_cycles_started = %u "
2445                  "is inconsistent with _old_marking_cycles_completed = %u",
2446                  _old_marking_cycles_started, _old_marking_cycles_completed));
2447 
2448   _old_marking_cycles_completed += 1;
2449 
2450   // We need to clear the "in_progress" flag in the CM thread before
2451   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2452   // is set) so that if a waiter requests another System.gc() it doesn't
2453   // incorrectly see that a marking cycle is still in progress.
2454   if (concurrent) {
2455     _cmThread->clear_in_progress();
2456   }
2457 
2458   // This notify_all() will ensure that a thread that called
2459   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2460   // and it's waiting for a full GC to finish will be woken up. It is
2461   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2462   FullGCCount_lock->notify_all();
2463 }
2464 
2465 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2466   _concurrent_cycle_started = true;
2467   _gc_timer_cm->register_gc_start(start_time);
2468 
2469   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2470   trace_heap_before_gc(_gc_tracer_cm);
2471 }
2472 
2473 void G1CollectedHeap::register_concurrent_cycle_end() {
2474   if (_concurrent_cycle_started) {
2475     if (_cm->has_aborted()) {
2476       _gc_tracer_cm->report_concurrent_mode_failure();
2477     }
2478 
2479     _gc_timer_cm->register_gc_end();
2480     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2481 
2482     _concurrent_cycle_started = false;
2483   }
2484 }
2485 
2486 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2487   if (_concurrent_cycle_started) {
2488     trace_heap_after_gc(_gc_tracer_cm);
2489   }
2490 }
2491 
2492 G1YCType G1CollectedHeap::yc_type() {
2493   bool is_young = g1_policy()->gcs_are_young();
2494   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2495   bool is_during_mark = mark_in_progress();
2496 
2497   if (is_initial_mark) {
2498     return InitialMark;
2499   } else if (is_during_mark) {
2500     return DuringMark;
2501   } else if (is_young) {
2502     return Normal;
2503   } else {
2504     return Mixed;
2505   }
2506 }
2507 
2508 void G1CollectedHeap::collect(GCCause::Cause cause) {
2509   assert_heap_not_locked();
2510 
2511   unsigned int gc_count_before;
2512   unsigned int old_marking_count_before;
2513   bool retry_gc;
2514 
2515   do {
2516     retry_gc = false;
2517 
2518     {
2519       MutexLocker ml(Heap_lock);
2520 
2521       // Read the GC count while holding the Heap_lock
2522       gc_count_before = total_collections();
2523       old_marking_count_before = _old_marking_cycles_started;
2524     }
2525 
2526     if (should_do_concurrent_full_gc(cause)) {
2527       // Schedule an initial-mark evacuation pause that will start a
2528       // concurrent cycle. We're setting word_size to 0 which means that
2529       // we are not requesting a post-GC allocation.
2530       VM_G1IncCollectionPause op(gc_count_before,
2531                                  0,     /* word_size */
2532                                  true,  /* should_initiate_conc_mark */
2533                                  g1_policy()->max_pause_time_ms(),
2534                                  cause);
2535 
2536       VMThread::execute(&op);
2537       if (!op.pause_succeeded()) {
2538         if (old_marking_count_before == _old_marking_cycles_started) {
2539           retry_gc = op.should_retry_gc();
2540         } else {
2541           // A Full GC happened while we were trying to schedule the
2542           // initial-mark GC. No point in starting a new cycle given
2543           // that the whole heap was collected anyway.
2544         }
2545 
2546         if (retry_gc) {
2547           if (GC_locker::is_active_and_needs_gc()) {
2548             GC_locker::stall_until_clear();
2549           }
2550         }
2551       }
2552     } else {
2553       if (cause == GCCause::_gc_locker
2554           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2555 
2556         // Schedule a standard evacuation pause. We're setting word_size
2557         // to 0 which means that we are not requesting a post-GC allocation.
2558         VM_G1IncCollectionPause op(gc_count_before,
2559                                    0,     /* word_size */
2560                                    false, /* should_initiate_conc_mark */
2561                                    g1_policy()->max_pause_time_ms(),
2562                                    cause);
2563         VMThread::execute(&op);
2564       } else {
2565         // Schedule a Full GC.
2566         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2567         VMThread::execute(&op);
2568       }
2569     }
2570   } while (retry_gc);
2571 }
2572 
2573 bool G1CollectedHeap::is_in(const void* p) const {
2574   if (_g1_committed.contains(p)) {
2575     // Given that we know that p is in the committed space,
2576     // heap_region_containing_raw() should successfully
2577     // return the containing region.
2578     HeapRegion* hr = heap_region_containing_raw(p);
2579     return hr->is_in(p);
2580   } else {
2581     return false;
2582   }
2583 }
2584 
2585 // Iteration functions.
2586 
2587 // Iterates an OopClosure over all ref-containing fields of objects
2588 // within a HeapRegion.
2589 
2590 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2591   MemRegion _mr;
2592   ExtendedOopClosure* _cl;
2593 public:
2594   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2595     : _mr(mr), _cl(cl) {}
2596   bool doHeapRegion(HeapRegion* r) {
2597     if (!r->continuesHumongous()) {
2598       r->oop_iterate(_cl);
2599     }
2600     return false;
2601   }
2602 };
2603 
2604 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2605   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2606   heap_region_iterate(&blk);
2607 }
2608 
2609 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2610   IterateOopClosureRegionClosure blk(mr, cl);
2611   heap_region_iterate(&blk);
2612 }
2613 
2614 // Iterates an ObjectClosure over all objects within a HeapRegion.
2615 
2616 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2617   ObjectClosure* _cl;
2618 public:
2619   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2620   bool doHeapRegion(HeapRegion* r) {
2621     if (! r->continuesHumongous()) {
2622       r->object_iterate(_cl);
2623     }
2624     return false;
2625   }
2626 };
2627 
2628 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2629   IterateObjectClosureRegionClosure blk(cl);
2630   heap_region_iterate(&blk);
2631 }
2632 
2633 // Calls a SpaceClosure on a HeapRegion.
2634 
2635 class SpaceClosureRegionClosure: public HeapRegionClosure {
2636   SpaceClosure* _cl;
2637 public:
2638   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2639   bool doHeapRegion(HeapRegion* r) {
2640     _cl->do_space(r);
2641     return false;
2642   }
2643 };
2644 
2645 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2646   SpaceClosureRegionClosure blk(cl);
2647   heap_region_iterate(&blk);
2648 }
2649 
2650 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2651   _hrs.iterate(cl);
2652 }
2653 
2654 void
2655 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2656                                                  uint worker_id,
2657                                                  uint no_of_par_workers,
2658                                                  jint claim_value) {
2659   const uint regions = n_regions();
2660   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2661                              no_of_par_workers :
2662                              1);
2663   assert(UseDynamicNumberOfGCThreads ||
2664          no_of_par_workers == workers()->total_workers(),
2665          "Non dynamic should use fixed number of workers");
2666   // try to spread out the starting points of the workers
2667   const HeapRegion* start_hr =
2668                         start_region_for_worker(worker_id, no_of_par_workers);
2669   const uint start_index = start_hr->hrs_index();
2670 
2671   // each worker will actually look at all regions
2672   for (uint count = 0; count < regions; ++count) {
2673     const uint index = (start_index + count) % regions;
2674     assert(0 <= index && index < regions, "sanity");
2675     HeapRegion* r = region_at(index);
2676     // we'll ignore "continues humongous" regions (we'll process them
2677     // when we come across their corresponding "start humongous"
2678     // region) and regions already claimed
2679     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2680       continue;
2681     }
2682     // OK, try to claim it
2683     if (r->claimHeapRegion(claim_value)) {
2684       // success!
2685       assert(!r->continuesHumongous(), "sanity");
2686       if (r->startsHumongous()) {
2687         // If the region is "starts humongous" we'll iterate over its
2688         // "continues humongous" first; in fact we'll do them
2689         // first. The order is important. In on case, calling the
2690         // closure on the "starts humongous" region might de-allocate
2691         // and clear all its "continues humongous" regions and, as a
2692         // result, we might end up processing them twice. So, we'll do
2693         // them first (notice: most closures will ignore them anyway) and
2694         // then we'll do the "starts humongous" region.
2695         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2696           HeapRegion* chr = region_at(ch_index);
2697 
2698           // if the region has already been claimed or it's not
2699           // "continues humongous" we're done
2700           if (chr->claim_value() == claim_value ||
2701               !chr->continuesHumongous()) {
2702             break;
2703           }
2704 
2705           // No one should have claimed it directly. We can given
2706           // that we claimed its "starts humongous" region.
2707           assert(chr->claim_value() != claim_value, "sanity");
2708           assert(chr->humongous_start_region() == r, "sanity");
2709 
2710           if (chr->claimHeapRegion(claim_value)) {
2711             // we should always be able to claim it; no one else should
2712             // be trying to claim this region
2713 
2714             bool res2 = cl->doHeapRegion(chr);
2715             assert(!res2, "Should not abort");
2716 
2717             // Right now, this holds (i.e., no closure that actually
2718             // does something with "continues humongous" regions
2719             // clears them). We might have to weaken it in the future,
2720             // but let's leave these two asserts here for extra safety.
2721             assert(chr->continuesHumongous(), "should still be the case");
2722             assert(chr->humongous_start_region() == r, "sanity");
2723           } else {
2724             guarantee(false, "we should not reach here");
2725           }
2726         }
2727       }
2728 
2729       assert(!r->continuesHumongous(), "sanity");
2730       bool res = cl->doHeapRegion(r);
2731       assert(!res, "Should not abort");
2732     }
2733   }
2734 }
2735 
2736 class ResetClaimValuesClosure: public HeapRegionClosure {
2737 public:
2738   bool doHeapRegion(HeapRegion* r) {
2739     r->set_claim_value(HeapRegion::InitialClaimValue);
2740     return false;
2741   }
2742 };
2743 
2744 void G1CollectedHeap::reset_heap_region_claim_values() {
2745   ResetClaimValuesClosure blk;
2746   heap_region_iterate(&blk);
2747 }
2748 
2749 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2750   ResetClaimValuesClosure blk;
2751   collection_set_iterate(&blk);
2752 }
2753 
2754 #ifdef ASSERT
2755 // This checks whether all regions in the heap have the correct claim
2756 // value. I also piggy-backed on this a check to ensure that the
2757 // humongous_start_region() information on "continues humongous"
2758 // regions is correct.
2759 
2760 class CheckClaimValuesClosure : public HeapRegionClosure {
2761 private:
2762   jint _claim_value;
2763   uint _failures;
2764   HeapRegion* _sh_region;
2765 
2766 public:
2767   CheckClaimValuesClosure(jint claim_value) :
2768     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2769   bool doHeapRegion(HeapRegion* r) {
2770     if (r->claim_value() != _claim_value) {
2771       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2772                              "claim value = %d, should be %d",
2773                              HR_FORMAT_PARAMS(r),
2774                              r->claim_value(), _claim_value);
2775       ++_failures;
2776     }
2777     if (!r->isHumongous()) {
2778       _sh_region = NULL;
2779     } else if (r->startsHumongous()) {
2780       _sh_region = r;
2781     } else if (r->continuesHumongous()) {
2782       if (r->humongous_start_region() != _sh_region) {
2783         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2784                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2785                                HR_FORMAT_PARAMS(r),
2786                                r->humongous_start_region(),
2787                                _sh_region);
2788         ++_failures;
2789       }
2790     }
2791     return false;
2792   }
2793   uint failures() { return _failures; }
2794 };
2795 
2796 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2797   CheckClaimValuesClosure cl(claim_value);
2798   heap_region_iterate(&cl);
2799   return cl.failures() == 0;
2800 }
2801 
2802 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2803 private:
2804   jint _claim_value;
2805   uint _failures;
2806 
2807 public:
2808   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2809     _claim_value(claim_value), _failures(0) { }
2810 
2811   uint failures() { return _failures; }
2812 
2813   bool doHeapRegion(HeapRegion* hr) {
2814     assert(hr->in_collection_set(), "how?");
2815     assert(!hr->isHumongous(), "H-region in CSet");
2816     if (hr->claim_value() != _claim_value) {
2817       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2818                              "claim value = %d, should be %d",
2819                              HR_FORMAT_PARAMS(hr),
2820                              hr->claim_value(), _claim_value);
2821       _failures += 1;
2822     }
2823     return false;
2824   }
2825 };
2826 
2827 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2828   CheckClaimValuesInCSetHRClosure cl(claim_value);
2829   collection_set_iterate(&cl);
2830   return cl.failures() == 0;
2831 }
2832 #endif // ASSERT
2833 
2834 // Clear the cached CSet starting regions and (more importantly)
2835 // the time stamps. Called when we reset the GC time stamp.
2836 void G1CollectedHeap::clear_cset_start_regions() {
2837   assert(_worker_cset_start_region != NULL, "sanity");
2838   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2839 
2840   int n_queues = MAX2((int)ParallelGCThreads, 1);
2841   for (int i = 0; i < n_queues; i++) {
2842     _worker_cset_start_region[i] = NULL;
2843     _worker_cset_start_region_time_stamp[i] = 0;
2844   }
2845 }
2846 
2847 // Given the id of a worker, obtain or calculate a suitable
2848 // starting region for iterating over the current collection set.
2849 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2850   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2851 
2852   HeapRegion* result = NULL;
2853   unsigned gc_time_stamp = get_gc_time_stamp();
2854 
2855   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2856     // Cached starting region for current worker was set
2857     // during the current pause - so it's valid.
2858     // Note: the cached starting heap region may be NULL
2859     // (when the collection set is empty).
2860     result = _worker_cset_start_region[worker_i];
2861     assert(result == NULL || result->in_collection_set(), "sanity");
2862     return result;
2863   }
2864 
2865   // The cached entry was not valid so let's calculate
2866   // a suitable starting heap region for this worker.
2867 
2868   // We want the parallel threads to start their collection
2869   // set iteration at different collection set regions to
2870   // avoid contention.
2871   // If we have:
2872   //          n collection set regions
2873   //          p threads
2874   // Then thread t will start at region floor ((t * n) / p)
2875 
2876   result = g1_policy()->collection_set();
2877   if (G1CollectedHeap::use_parallel_gc_threads()) {
2878     uint cs_size = g1_policy()->cset_region_length();
2879     uint active_workers = workers()->active_workers();
2880     assert(UseDynamicNumberOfGCThreads ||
2881              active_workers == workers()->total_workers(),
2882              "Unless dynamic should use total workers");
2883 
2884     uint end_ind   = (cs_size * worker_i) / active_workers;
2885     uint start_ind = 0;
2886 
2887     if (worker_i > 0 &&
2888         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2889       // Previous workers starting region is valid
2890       // so let's iterate from there
2891       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2892       result = _worker_cset_start_region[worker_i - 1];
2893     }
2894 
2895     for (uint i = start_ind; i < end_ind; i++) {
2896       result = result->next_in_collection_set();
2897     }
2898   }
2899 
2900   // Note: the calculated starting heap region may be NULL
2901   // (when the collection set is empty).
2902   assert(result == NULL || result->in_collection_set(), "sanity");
2903   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2904          "should be updated only once per pause");
2905   _worker_cset_start_region[worker_i] = result;
2906   OrderAccess::storestore();
2907   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2908   return result;
2909 }
2910 
2911 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2912                                                      uint no_of_par_workers) {
2913   uint worker_num =
2914            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2915   assert(UseDynamicNumberOfGCThreads ||
2916          no_of_par_workers == workers()->total_workers(),
2917          "Non dynamic should use fixed number of workers");
2918   const uint start_index = n_regions() * worker_i / worker_num;
2919   return region_at(start_index);
2920 }
2921 
2922 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2923   HeapRegion* r = g1_policy()->collection_set();
2924   while (r != NULL) {
2925     HeapRegion* next = r->next_in_collection_set();
2926     if (cl->doHeapRegion(r)) {
2927       cl->incomplete();
2928       return;
2929     }
2930     r = next;
2931   }
2932 }
2933 
2934 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2935                                                   HeapRegionClosure *cl) {
2936   if (r == NULL) {
2937     // The CSet is empty so there's nothing to do.
2938     return;
2939   }
2940 
2941   assert(r->in_collection_set(),
2942          "Start region must be a member of the collection set.");
2943   HeapRegion* cur = r;
2944   while (cur != NULL) {
2945     HeapRegion* next = cur->next_in_collection_set();
2946     if (cl->doHeapRegion(cur) && false) {
2947       cl->incomplete();
2948       return;
2949     }
2950     cur = next;
2951   }
2952   cur = g1_policy()->collection_set();
2953   while (cur != r) {
2954     HeapRegion* next = cur->next_in_collection_set();
2955     if (cl->doHeapRegion(cur) && false) {
2956       cl->incomplete();
2957       return;
2958     }
2959     cur = next;
2960   }
2961 }
2962 
2963 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2964   return n_regions() > 0 ? region_at(0) : NULL;
2965 }
2966 
2967 
2968 Space* G1CollectedHeap::space_containing(const void* addr) const {
2969   Space* res = heap_region_containing(addr);
2970   return res;
2971 }
2972 
2973 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2974   Space* sp = space_containing(addr);
2975   if (sp != NULL) {
2976     return sp->block_start(addr);
2977   }
2978   return NULL;
2979 }
2980 
2981 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2982   Space* sp = space_containing(addr);
2983   assert(sp != NULL, "block_size of address outside of heap");
2984   return sp->block_size(addr);
2985 }
2986 
2987 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2988   Space* sp = space_containing(addr);
2989   return sp->block_is_obj(addr);
2990 }
2991 
2992 bool G1CollectedHeap::supports_tlab_allocation() const {
2993   return true;
2994 }
2995 
2996 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2997   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2998 }
2999 
3000 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3001   return young_list()->eden_used_bytes();
3002 }
3003 
3004 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3005 // must be smaller than the humongous object limit.
3006 size_t G1CollectedHeap::max_tlab_size() const {
3007   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3008 }
3009 
3010 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3011   // Return the remaining space in the cur alloc region, but not less than
3012   // the min TLAB size.
3013 
3014   // Also, this value can be at most the humongous object threshold,
3015   // since we can't allow tlabs to grow big enough to accommodate
3016   // humongous objects.
3017 
3018   HeapRegion* hr = _mutator_alloc_region.get();
3019   size_t max_tlab = max_tlab_size() * wordSize;
3020   if (hr == NULL) {
3021     return max_tlab;
3022   } else {
3023     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3024   }
3025 }
3026 
3027 size_t G1CollectedHeap::max_capacity() const {
3028   return _g1_reserved.byte_size();
3029 }
3030 
3031 jlong G1CollectedHeap::millis_since_last_gc() {
3032   // assert(false, "NYI");
3033   return 0;
3034 }
3035 
3036 void G1CollectedHeap::prepare_for_verify() {
3037   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3038     ensure_parsability(false);
3039   }
3040   g1_rem_set()->prepare_for_verify();
3041 }
3042 
3043 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3044                                               VerifyOption vo) {
3045   switch (vo) {
3046   case VerifyOption_G1UsePrevMarking:
3047     return hr->obj_allocated_since_prev_marking(obj);
3048   case VerifyOption_G1UseNextMarking:
3049     return hr->obj_allocated_since_next_marking(obj);
3050   case VerifyOption_G1UseMarkWord:
3051     return false;
3052   default:
3053     ShouldNotReachHere();
3054   }
3055   return false; // keep some compilers happy
3056 }
3057 
3058 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3059   switch (vo) {
3060   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3061   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3062   case VerifyOption_G1UseMarkWord:    return NULL;
3063   default:                            ShouldNotReachHere();
3064   }
3065   return NULL; // keep some compilers happy
3066 }
3067 
3068 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3069   switch (vo) {
3070   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3071   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3072   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3073   default:                            ShouldNotReachHere();
3074   }
3075   return false; // keep some compilers happy
3076 }
3077 
3078 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3079   switch (vo) {
3080   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3081   case VerifyOption_G1UseNextMarking: return "NTAMS";
3082   case VerifyOption_G1UseMarkWord:    return "NONE";
3083   default:                            ShouldNotReachHere();
3084   }
3085   return NULL; // keep some compilers happy
3086 }
3087 
3088 class VerifyRootsClosure: public OopClosure {
3089 private:
3090   G1CollectedHeap* _g1h;
3091   VerifyOption     _vo;
3092   bool             _failures;
3093 public:
3094   // _vo == UsePrevMarking -> use "prev" marking information,
3095   // _vo == UseNextMarking -> use "next" marking information,
3096   // _vo == UseMarkWord    -> use mark word from object header.
3097   VerifyRootsClosure(VerifyOption vo) :
3098     _g1h(G1CollectedHeap::heap()),
3099     _vo(vo),
3100     _failures(false) { }
3101 
3102   bool failures() { return _failures; }
3103 
3104   template <class T> void do_oop_nv(T* p) {
3105     T heap_oop = oopDesc::load_heap_oop(p);
3106     if (!oopDesc::is_null(heap_oop)) {
3107       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3108       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3109         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3110                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3111         if (_vo == VerifyOption_G1UseMarkWord) {
3112           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3113         }
3114         obj->print_on(gclog_or_tty);
3115         _failures = true;
3116       }
3117     }
3118   }
3119 
3120   void do_oop(oop* p)       { do_oop_nv(p); }
3121   void do_oop(narrowOop* p) { do_oop_nv(p); }
3122 };
3123 
3124 class G1VerifyCodeRootOopClosure: public OopClosure {
3125   G1CollectedHeap* _g1h;
3126   OopClosure* _root_cl;
3127   nmethod* _nm;
3128   VerifyOption _vo;
3129   bool _failures;
3130 
3131   template <class T> void do_oop_work(T* p) {
3132     // First verify that this root is live
3133     _root_cl->do_oop(p);
3134 
3135     if (!G1VerifyHeapRegionCodeRoots) {
3136       // We're not verifying the code roots attached to heap region.
3137       return;
3138     }
3139 
3140     // Don't check the code roots during marking verification in a full GC
3141     if (_vo == VerifyOption_G1UseMarkWord) {
3142       return;
3143     }
3144 
3145     // Now verify that the current nmethod (which contains p) is
3146     // in the code root list of the heap region containing the
3147     // object referenced by p.
3148 
3149     T heap_oop = oopDesc::load_heap_oop(p);
3150     if (!oopDesc::is_null(heap_oop)) {
3151       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3152 
3153       // Now fetch the region containing the object
3154       HeapRegion* hr = _g1h->heap_region_containing(obj);
3155       HeapRegionRemSet* hrrs = hr->rem_set();
3156       // Verify that the strong code root list for this region
3157       // contains the nmethod
3158       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3159         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3160                               "from nmethod "PTR_FORMAT" not in strong "
3161                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3162                               p, _nm, hr->bottom(), hr->end());
3163         _failures = true;
3164       }
3165     }
3166   }
3167 
3168 public:
3169   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3170     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3171 
3172   void do_oop(oop* p) { do_oop_work(p); }
3173   void do_oop(narrowOop* p) { do_oop_work(p); }
3174 
3175   void set_nmethod(nmethod* nm) { _nm = nm; }
3176   bool failures() { return _failures; }
3177 };
3178 
3179 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3180   G1VerifyCodeRootOopClosure* _oop_cl;
3181 
3182 public:
3183   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3184     _oop_cl(oop_cl) {}
3185 
3186   void do_code_blob(CodeBlob* cb) {
3187     nmethod* nm = cb->as_nmethod_or_null();
3188     if (nm != NULL) {
3189       _oop_cl->set_nmethod(nm);
3190       nm->oops_do(_oop_cl);
3191     }
3192   }
3193 };
3194 
3195 class YoungRefCounterClosure : public OopClosure {
3196   G1CollectedHeap* _g1h;
3197   int              _count;
3198  public:
3199   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3200   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3201   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3202 
3203   int count() { return _count; }
3204   void reset_count() { _count = 0; };
3205 };
3206 
3207 class VerifyKlassClosure: public KlassClosure {
3208   YoungRefCounterClosure _young_ref_counter_closure;
3209   OopClosure *_oop_closure;
3210  public:
3211   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3212   void do_klass(Klass* k) {
3213     k->oops_do(_oop_closure);
3214 
3215     _young_ref_counter_closure.reset_count();
3216     k->oops_do(&_young_ref_counter_closure);
3217     if (_young_ref_counter_closure.count() > 0) {
3218       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3219     }
3220   }
3221 };
3222 
3223 class VerifyLivenessOopClosure: public OopClosure {
3224   G1CollectedHeap* _g1h;
3225   VerifyOption _vo;
3226 public:
3227   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3228     _g1h(g1h), _vo(vo)
3229   { }
3230   void do_oop(narrowOop *p) { do_oop_work(p); }
3231   void do_oop(      oop *p) { do_oop_work(p); }
3232 
3233   template <class T> void do_oop_work(T *p) {
3234     oop obj = oopDesc::load_decode_heap_oop(p);
3235     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3236               "Dead object referenced by a not dead object");
3237   }
3238 };
3239 
3240 class VerifyObjsInRegionClosure: public ObjectClosure {
3241 private:
3242   G1CollectedHeap* _g1h;
3243   size_t _live_bytes;
3244   HeapRegion *_hr;
3245   VerifyOption _vo;
3246 public:
3247   // _vo == UsePrevMarking -> use "prev" marking information,
3248   // _vo == UseNextMarking -> use "next" marking information,
3249   // _vo == UseMarkWord    -> use mark word from object header.
3250   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3251     : _live_bytes(0), _hr(hr), _vo(vo) {
3252     _g1h = G1CollectedHeap::heap();
3253   }
3254   void do_object(oop o) {
3255     VerifyLivenessOopClosure isLive(_g1h, _vo);
3256     assert(o != NULL, "Huh?");
3257     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3258       // If the object is alive according to the mark word,
3259       // then verify that the marking information agrees.
3260       // Note we can't verify the contra-positive of the
3261       // above: if the object is dead (according to the mark
3262       // word), it may not be marked, or may have been marked
3263       // but has since became dead, or may have been allocated
3264       // since the last marking.
3265       if (_vo == VerifyOption_G1UseMarkWord) {
3266         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3267       }
3268 
3269       o->oop_iterate_no_header(&isLive);
3270       if (!_hr->obj_allocated_since_prev_marking(o)) {
3271         size_t obj_size = o->size();    // Make sure we don't overflow
3272         _live_bytes += (obj_size * HeapWordSize);
3273       }
3274     }
3275   }
3276   size_t live_bytes() { return _live_bytes; }
3277 };
3278 
3279 class PrintObjsInRegionClosure : public ObjectClosure {
3280   HeapRegion *_hr;
3281   G1CollectedHeap *_g1;
3282 public:
3283   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3284     _g1 = G1CollectedHeap::heap();
3285   };
3286 
3287   void do_object(oop o) {
3288     if (o != NULL) {
3289       HeapWord *start = (HeapWord *) o;
3290       size_t word_sz = o->size();
3291       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3292                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3293                           (void*) o, word_sz,
3294                           _g1->isMarkedPrev(o),
3295                           _g1->isMarkedNext(o),
3296                           _hr->obj_allocated_since_prev_marking(o));
3297       HeapWord *end = start + word_sz;
3298       HeapWord *cur;
3299       int *val;
3300       for (cur = start; cur < end; cur++) {
3301         val = (int *) cur;
3302         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3303       }
3304     }
3305   }
3306 };
3307 
3308 class VerifyRegionClosure: public HeapRegionClosure {
3309 private:
3310   bool             _par;
3311   VerifyOption     _vo;
3312   bool             _failures;
3313 public:
3314   // _vo == UsePrevMarking -> use "prev" marking information,
3315   // _vo == UseNextMarking -> use "next" marking information,
3316   // _vo == UseMarkWord    -> use mark word from object header.
3317   VerifyRegionClosure(bool par, VerifyOption vo)
3318     : _par(par),
3319       _vo(vo),
3320       _failures(false) {}
3321 
3322   bool failures() {
3323     return _failures;
3324   }
3325 
3326   bool doHeapRegion(HeapRegion* r) {
3327     if (!r->continuesHumongous()) {
3328       bool failures = false;
3329       r->verify(_vo, &failures);
3330       if (failures) {
3331         _failures = true;
3332       } else {
3333         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3334         r->object_iterate(&not_dead_yet_cl);
3335         if (_vo != VerifyOption_G1UseNextMarking) {
3336           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3337             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3338                                    "max_live_bytes "SIZE_FORMAT" "
3339                                    "< calculated "SIZE_FORMAT,
3340                                    r->bottom(), r->end(),
3341                                    r->max_live_bytes(),
3342                                  not_dead_yet_cl.live_bytes());
3343             _failures = true;
3344           }
3345         } else {
3346           // When vo == UseNextMarking we cannot currently do a sanity
3347           // check on the live bytes as the calculation has not been
3348           // finalized yet.
3349         }
3350       }
3351     }
3352     return false; // stop the region iteration if we hit a failure
3353   }
3354 };
3355 
3356 // This is the task used for parallel verification of the heap regions
3357 
3358 class G1ParVerifyTask: public AbstractGangTask {
3359 private:
3360   G1CollectedHeap* _g1h;
3361   VerifyOption     _vo;
3362   bool             _failures;
3363 
3364 public:
3365   // _vo == UsePrevMarking -> use "prev" marking information,
3366   // _vo == UseNextMarking -> use "next" marking information,
3367   // _vo == UseMarkWord    -> use mark word from object header.
3368   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3369     AbstractGangTask("Parallel verify task"),
3370     _g1h(g1h),
3371     _vo(vo),
3372     _failures(false) { }
3373 
3374   bool failures() {
3375     return _failures;
3376   }
3377 
3378   void work(uint worker_id) {
3379     HandleMark hm;
3380     VerifyRegionClosure blk(true, _vo);
3381     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3382                                           _g1h->workers()->active_workers(),
3383                                           HeapRegion::ParVerifyClaimValue);
3384     if (blk.failures()) {
3385       _failures = true;
3386     }
3387   }
3388 };
3389 
3390 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3391   if (SafepointSynchronize::is_at_safepoint()) {
3392     assert(Thread::current()->is_VM_thread(),
3393            "Expected to be executed serially by the VM thread at this point");
3394 
3395     if (!silent) { gclog_or_tty->print("Roots "); }
3396     VerifyRootsClosure rootsCl(vo);
3397     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3398     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3399     VerifyKlassClosure klassCl(this, &rootsCl);
3400 
3401     // We apply the relevant closures to all the oops in the
3402     // system dictionary, the string table and the code cache.
3403     const int so = SO_AllClasses | SO_Strings | SO_AllCodeCache;
3404 
3405     // Need cleared claim bits for the strong roots processing
3406     ClassLoaderDataGraph::clear_claimed_marks();
3407 
3408     process_strong_roots(true,      // activate StrongRootsScope
3409                          ScanningOption(so),  // roots scanning options
3410                          &rootsCl,
3411                          &blobsCl,
3412                          &klassCl
3413                          );
3414 
3415     bool failures = rootsCl.failures() || codeRootsCl.failures();
3416 
3417     if (vo != VerifyOption_G1UseMarkWord) {
3418       // If we're verifying during a full GC then the region sets
3419       // will have been torn down at the start of the GC. Therefore
3420       // verifying the region sets will fail. So we only verify
3421       // the region sets when not in a full GC.
3422       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3423       verify_region_sets();
3424     }
3425 
3426     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3427     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3428       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3429              "sanity check");
3430 
3431       G1ParVerifyTask task(this, vo);
3432       assert(UseDynamicNumberOfGCThreads ||
3433         workers()->active_workers() == workers()->total_workers(),
3434         "If not dynamic should be using all the workers");
3435       int n_workers = workers()->active_workers();
3436       set_par_threads(n_workers);
3437       workers()->run_task(&task);
3438       set_par_threads(0);
3439       if (task.failures()) {
3440         failures = true;
3441       }
3442 
3443       // Checks that the expected amount of parallel work was done.
3444       // The implication is that n_workers is > 0.
3445       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3446              "sanity check");
3447 
3448       reset_heap_region_claim_values();
3449 
3450       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3451              "sanity check");
3452     } else {
3453       VerifyRegionClosure blk(false, vo);
3454       heap_region_iterate(&blk);
3455       if (blk.failures()) {
3456         failures = true;
3457       }
3458     }
3459     if (!silent) gclog_or_tty->print("RemSet ");
3460     rem_set()->verify();
3461 
3462     if (failures) {
3463       gclog_or_tty->print_cr("Heap:");
3464       // It helps to have the per-region information in the output to
3465       // help us track down what went wrong. This is why we call
3466       // print_extended_on() instead of print_on().
3467       print_extended_on(gclog_or_tty);
3468       gclog_or_tty->print_cr("");
3469 #ifndef PRODUCT
3470       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3471         concurrent_mark()->print_reachable("at-verification-failure",
3472                                            vo, false /* all */);
3473       }
3474 #endif
3475       gclog_or_tty->flush();
3476     }
3477     guarantee(!failures, "there should not have been any failures");
3478   } else {
3479     if (!silent)
3480       gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3481   }
3482 }
3483 
3484 void G1CollectedHeap::verify(bool silent) {
3485   verify(silent, VerifyOption_G1UsePrevMarking);
3486 }
3487 
3488 double G1CollectedHeap::verify(bool guard, const char* msg) {
3489   double verify_time_ms = 0.0;
3490 
3491   if (guard && total_collections() >= VerifyGCStartAt) {
3492     double verify_start = os::elapsedTime();
3493     HandleMark hm;  // Discard invalid handles created during verification
3494     prepare_for_verify();
3495     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3496     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3497   }
3498 
3499   return verify_time_ms;
3500 }
3501 
3502 void G1CollectedHeap::verify_before_gc() {
3503   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3504   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3505 }
3506 
3507 void G1CollectedHeap::verify_after_gc() {
3508   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3509   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3510 }
3511 
3512 class PrintRegionClosure: public HeapRegionClosure {
3513   outputStream* _st;
3514 public:
3515   PrintRegionClosure(outputStream* st) : _st(st) {}
3516   bool doHeapRegion(HeapRegion* r) {
3517     r->print_on(_st);
3518     return false;
3519   }
3520 };
3521 
3522 void G1CollectedHeap::print_on(outputStream* st) const {
3523   st->print(" %-20s", "garbage-first heap");
3524   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3525             capacity()/K, used_unlocked()/K);
3526   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3527             _g1_storage.low_boundary(),
3528             _g1_storage.high(),
3529             _g1_storage.high_boundary());
3530   st->cr();
3531   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3532   uint young_regions = _young_list->length();
3533   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3534             (size_t) young_regions * HeapRegion::GrainBytes / K);
3535   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3536   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3537             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3538   st->cr();
3539   MetaspaceAux::print_on(st);
3540 }
3541 
3542 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3543   print_on(st);
3544 
3545   // Print the per-region information.
3546   st->cr();
3547   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3548                "HS=humongous(starts), HC=humongous(continues), "
3549                "CS=collection set, F=free, TS=gc time stamp, "
3550                "PTAMS=previous top-at-mark-start, "
3551                "NTAMS=next top-at-mark-start)");
3552   PrintRegionClosure blk(st);
3553   heap_region_iterate(&blk);
3554 }
3555 
3556 void G1CollectedHeap::print_on_error(outputStream* st) const {
3557   this->CollectedHeap::print_on_error(st);
3558 
3559   if (_cm != NULL) {
3560     st->cr();
3561     _cm->print_on_error(st);
3562   }
3563 }
3564 
3565 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3566   if (G1CollectedHeap::use_parallel_gc_threads()) {
3567     workers()->print_worker_threads_on(st);
3568   }
3569   _cmThread->print_on(st);
3570   st->cr();
3571   _cm->print_worker_threads_on(st);
3572   _cg1r->print_worker_threads_on(st);
3573 }
3574 
3575 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3576   if (G1CollectedHeap::use_parallel_gc_threads()) {
3577     workers()->threads_do(tc);
3578   }
3579   tc->do_thread(_cmThread);
3580   _cg1r->threads_do(tc);
3581 }
3582 
3583 void G1CollectedHeap::print_tracing_info() const {
3584   // We'll overload this to mean "trace GC pause statistics."
3585   if (TraceGen0Time || TraceGen1Time) {
3586     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3587     // to that.
3588     g1_policy()->print_tracing_info();
3589   }
3590   if (G1SummarizeRSetStats) {
3591     g1_rem_set()->print_summary_info();
3592   }
3593   if (G1SummarizeConcMark) {
3594     concurrent_mark()->print_summary_info();
3595   }
3596   g1_policy()->print_yg_surv_rate_info();
3597   SpecializationStats::print();
3598 }
3599 
3600 #ifndef PRODUCT
3601 // Helpful for debugging RSet issues.
3602 
3603 class PrintRSetsClosure : public HeapRegionClosure {
3604 private:
3605   const char* _msg;
3606   size_t _occupied_sum;
3607 
3608 public:
3609   bool doHeapRegion(HeapRegion* r) {
3610     HeapRegionRemSet* hrrs = r->rem_set();
3611     size_t occupied = hrrs->occupied();
3612     _occupied_sum += occupied;
3613 
3614     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3615                            HR_FORMAT_PARAMS(r));
3616     if (occupied == 0) {
3617       gclog_or_tty->print_cr("  RSet is empty");
3618     } else {
3619       hrrs->print();
3620     }
3621     gclog_or_tty->print_cr("----------");
3622     return false;
3623   }
3624 
3625   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3626     gclog_or_tty->cr();
3627     gclog_or_tty->print_cr("========================================");
3628     gclog_or_tty->print_cr(msg);
3629     gclog_or_tty->cr();
3630   }
3631 
3632   ~PrintRSetsClosure() {
3633     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3634     gclog_or_tty->print_cr("========================================");
3635     gclog_or_tty->cr();
3636   }
3637 };
3638 
3639 void G1CollectedHeap::print_cset_rsets() {
3640   PrintRSetsClosure cl("Printing CSet RSets");
3641   collection_set_iterate(&cl);
3642 }
3643 
3644 void G1CollectedHeap::print_all_rsets() {
3645   PrintRSetsClosure cl("Printing All RSets");;
3646   heap_region_iterate(&cl);
3647 }
3648 #endif // PRODUCT
3649 
3650 G1CollectedHeap* G1CollectedHeap::heap() {
3651   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3652          "not a garbage-first heap");
3653   return _g1h;
3654 }
3655 
3656 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3657   // always_do_update_barrier = false;
3658   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3659   // Fill TLAB's and such
3660   accumulate_statistics_all_tlabs();
3661   ensure_parsability(true);
3662 
3663   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3664       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3665     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3666   }
3667 }
3668 
3669 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3670 
3671   if (G1SummarizeRSetStats &&
3672       (G1SummarizeRSetStatsPeriod > 0) &&
3673       // we are at the end of the GC. Total collections has already been increased.
3674       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3675     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3676   }
3677 
3678   // FIXME: what is this about?
3679   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3680   // is set.
3681   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3682                         "derived pointer present"));
3683   // always_do_update_barrier = true;
3684 
3685   resize_all_tlabs();
3686 
3687   // We have just completed a GC. Update the soft reference
3688   // policy with the new heap occupancy
3689   Universe::update_heap_info_at_gc();
3690 }
3691 
3692 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3693                                                unsigned int gc_count_before,
3694                                                bool* succeeded,
3695                                                GCCause::Cause gc_cause) {
3696   assert_heap_not_locked_and_not_at_safepoint();
3697   g1_policy()->record_stop_world_start();
3698   VM_G1IncCollectionPause op(gc_count_before,
3699                              word_size,
3700                              false, /* should_initiate_conc_mark */
3701                              g1_policy()->max_pause_time_ms(),
3702                              gc_cause);
3703   VMThread::execute(&op);
3704 
3705   HeapWord* result = op.result();
3706   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3707   assert(result == NULL || ret_succeeded,
3708          "the result should be NULL if the VM did not succeed");
3709   *succeeded = ret_succeeded;
3710 
3711   assert_heap_not_locked();
3712   return result;
3713 }
3714 
3715 void
3716 G1CollectedHeap::doConcurrentMark() {
3717   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3718   if (!_cmThread->in_progress()) {
3719     _cmThread->set_started();
3720     CGC_lock->notify();
3721   }
3722 }
3723 
3724 size_t G1CollectedHeap::pending_card_num() {
3725   size_t extra_cards = 0;
3726   JavaThread *curr = Threads::first();
3727   while (curr != NULL) {
3728     DirtyCardQueue& dcq = curr->dirty_card_queue();
3729     extra_cards += dcq.size();
3730     curr = curr->next();
3731   }
3732   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3733   size_t buffer_size = dcqs.buffer_size();
3734   size_t buffer_num = dcqs.completed_buffers_num();
3735 
3736   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3737   // in bytes - not the number of 'entries'. We need to convert
3738   // into a number of cards.
3739   return (buffer_size * buffer_num + extra_cards) / oopSize;
3740 }
3741 
3742 size_t G1CollectedHeap::cards_scanned() {
3743   return g1_rem_set()->cardsScanned();
3744 }
3745 
3746 void
3747 G1CollectedHeap::setup_surviving_young_words() {
3748   assert(_surviving_young_words == NULL, "pre-condition");
3749   uint array_length = g1_policy()->young_cset_region_length();
3750   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3751   if (_surviving_young_words == NULL) {
3752     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3753                           "Not enough space for young surv words summary.");
3754   }
3755   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3756 #ifdef ASSERT
3757   for (uint i = 0;  i < array_length; ++i) {
3758     assert( _surviving_young_words[i] == 0, "memset above" );
3759   }
3760 #endif // !ASSERT
3761 }
3762 
3763 void
3764 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3765   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3766   uint array_length = g1_policy()->young_cset_region_length();
3767   for (uint i = 0; i < array_length; ++i) {
3768     _surviving_young_words[i] += surv_young_words[i];
3769   }
3770 }
3771 
3772 void
3773 G1CollectedHeap::cleanup_surviving_young_words() {
3774   guarantee( _surviving_young_words != NULL, "pre-condition" );
3775   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3776   _surviving_young_words = NULL;
3777 }
3778 
3779 #ifdef ASSERT
3780 class VerifyCSetClosure: public HeapRegionClosure {
3781 public:
3782   bool doHeapRegion(HeapRegion* hr) {
3783     // Here we check that the CSet region's RSet is ready for parallel
3784     // iteration. The fields that we'll verify are only manipulated
3785     // when the region is part of a CSet and is collected. Afterwards,
3786     // we reset these fields when we clear the region's RSet (when the
3787     // region is freed) so they are ready when the region is
3788     // re-allocated. The only exception to this is if there's an
3789     // evacuation failure and instead of freeing the region we leave
3790     // it in the heap. In that case, we reset these fields during
3791     // evacuation failure handling.
3792     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3793 
3794     // Here's a good place to add any other checks we'd like to
3795     // perform on CSet regions.
3796     return false;
3797   }
3798 };
3799 #endif // ASSERT
3800 
3801 #if TASKQUEUE_STATS
3802 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3803   st->print_raw_cr("GC Task Stats");
3804   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3805   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3806 }
3807 
3808 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3809   print_taskqueue_stats_hdr(st);
3810 
3811   TaskQueueStats totals;
3812   const int n = workers() != NULL ? workers()->total_workers() : 1;
3813   for (int i = 0; i < n; ++i) {
3814     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3815     totals += task_queue(i)->stats;
3816   }
3817   st->print_raw("tot "); totals.print(st); st->cr();
3818 
3819   DEBUG_ONLY(totals.verify());
3820 }
3821 
3822 void G1CollectedHeap::reset_taskqueue_stats() {
3823   const int n = workers() != NULL ? workers()->total_workers() : 1;
3824   for (int i = 0; i < n; ++i) {
3825     task_queue(i)->stats.reset();
3826   }
3827 }
3828 #endif // TASKQUEUE_STATS
3829 
3830 void G1CollectedHeap::log_gc_header() {
3831   if (!G1Log::fine()) {
3832     return;
3833   }
3834 
3835   gclog_or_tty->date_stamp(PrintGCDateStamps);
3836   gclog_or_tty->stamp(PrintGCTimeStamps);
3837 
3838   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3839     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3840     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3841 
3842   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3843 }
3844 
3845 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3846   if (!G1Log::fine()) {
3847     return;
3848   }
3849 
3850   if (G1Log::finer()) {
3851     if (evacuation_failed()) {
3852       gclog_or_tty->print(" (to-space exhausted)");
3853     }
3854     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3855     g1_policy()->phase_times()->note_gc_end();
3856     g1_policy()->phase_times()->print(pause_time_sec);
3857     g1_policy()->print_detailed_heap_transition();
3858   } else {
3859     if (evacuation_failed()) {
3860       gclog_or_tty->print("--");
3861     }
3862     g1_policy()->print_heap_transition();
3863     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3864   }
3865   gclog_or_tty->flush();
3866 }
3867 
3868 bool
3869 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3870   assert_at_safepoint(true /* should_be_vm_thread */);
3871   guarantee(!is_gc_active(), "collection is not reentrant");
3872 
3873   if (GC_locker::check_active_before_gc()) {
3874     return false;
3875   }
3876 
3877   _gc_timer_stw->register_gc_start();
3878 
3879   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3880 
3881   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3882   ResourceMark rm;
3883 
3884   print_heap_before_gc();
3885   trace_heap_before_gc(_gc_tracer_stw);
3886 
3887   HRSPhaseSetter x(HRSPhaseEvacuation);
3888   verify_region_sets_optional();
3889   verify_dirty_young_regions();
3890 
3891   // This call will decide whether this pause is an initial-mark
3892   // pause. If it is, during_initial_mark_pause() will return true
3893   // for the duration of this pause.
3894   g1_policy()->decide_on_conc_mark_initiation();
3895 
3896   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3897   assert(!g1_policy()->during_initial_mark_pause() ||
3898           g1_policy()->gcs_are_young(), "sanity");
3899 
3900   // We also do not allow mixed GCs during marking.
3901   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3902 
3903   // Record whether this pause is an initial mark. When the current
3904   // thread has completed its logging output and it's safe to signal
3905   // the CM thread, the flag's value in the policy has been reset.
3906   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3907 
3908   // Inner scope for scope based logging, timers, and stats collection
3909   {
3910     EvacuationInfo evacuation_info;
3911 
3912     if (g1_policy()->during_initial_mark_pause()) {
3913       // We are about to start a marking cycle, so we increment the
3914       // full collection counter.
3915       increment_old_marking_cycles_started();
3916       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3917     }
3918 
3919     _gc_tracer_stw->report_yc_type(yc_type());
3920 
3921     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3922 
3923     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3924                                 workers()->active_workers() : 1);
3925     double pause_start_sec = os::elapsedTime();
3926     g1_policy()->phase_times()->note_gc_start(active_workers);
3927     log_gc_header();
3928 
3929     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3930     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3931 
3932     // If the secondary_free_list is not empty, append it to the
3933     // free_list. No need to wait for the cleanup operation to finish;
3934     // the region allocation code will check the secondary_free_list
3935     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3936     // set, skip this step so that the region allocation code has to
3937     // get entries from the secondary_free_list.
3938     if (!G1StressConcRegionFreeing) {
3939       append_secondary_free_list_if_not_empty_with_lock();
3940     }
3941 
3942     assert(check_young_list_well_formed(), "young list should be well formed");
3943     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3944            "sanity check");
3945 
3946     // Don't dynamically change the number of GC threads this early.  A value of
3947     // 0 is used to indicate serial work.  When parallel work is done,
3948     // it will be set.
3949 
3950     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3951       IsGCActiveMark x;
3952 
3953       gc_prologue(false);
3954       increment_total_collections(false /* full gc */);
3955       increment_gc_time_stamp();
3956 
3957       verify_before_gc();
3958 
3959       COMPILER2_PRESENT(DerivedPointerTable::clear());
3960 
3961       // Please see comment in g1CollectedHeap.hpp and
3962       // G1CollectedHeap::ref_processing_init() to see how
3963       // reference processing currently works in G1.
3964 
3965       // Enable discovery in the STW reference processor
3966       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3967                                             true /*verify_no_refs*/);
3968 
3969       {
3970         // We want to temporarily turn off discovery by the
3971         // CM ref processor, if necessary, and turn it back on
3972         // on again later if we do. Using a scoped
3973         // NoRefDiscovery object will do this.
3974         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3975 
3976         // Forget the current alloc region (we might even choose it to be part
3977         // of the collection set!).
3978         release_mutator_alloc_region();
3979 
3980         // We should call this after we retire the mutator alloc
3981         // region(s) so that all the ALLOC / RETIRE events are generated
3982         // before the start GC event.
3983         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3984 
3985         // This timing is only used by the ergonomics to handle our pause target.
3986         // It is unclear why this should not include the full pause. We will
3987         // investigate this in CR 7178365.
3988         //
3989         // Preserving the old comment here if that helps the investigation:
3990         //
3991         // The elapsed time induced by the start time below deliberately elides
3992         // the possible verification above.
3993         double sample_start_time_sec = os::elapsedTime();
3994 
3995 #if YOUNG_LIST_VERBOSE
3996         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3997         _young_list->print();
3998         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3999 #endif // YOUNG_LIST_VERBOSE
4000 
4001         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4002 
4003         double scan_wait_start = os::elapsedTime();
4004         // We have to wait until the CM threads finish scanning the
4005         // root regions as it's the only way to ensure that all the
4006         // objects on them have been correctly scanned before we start
4007         // moving them during the GC.
4008         bool waited = _cm->root_regions()->wait_until_scan_finished();
4009         double wait_time_ms = 0.0;
4010         if (waited) {
4011           double scan_wait_end = os::elapsedTime();
4012           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4013         }
4014         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4015 
4016 #if YOUNG_LIST_VERBOSE
4017         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4018         _young_list->print();
4019 #endif // YOUNG_LIST_VERBOSE
4020 
4021         if (g1_policy()->during_initial_mark_pause()) {
4022           concurrent_mark()->checkpointRootsInitialPre();
4023         }
4024 
4025 #if YOUNG_LIST_VERBOSE
4026         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4027         _young_list->print();
4028         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4029 #endif // YOUNG_LIST_VERBOSE
4030 
4031         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4032 
4033         _cm->note_start_of_gc();
4034         // We should not verify the per-thread SATB buffers given that
4035         // we have not filtered them yet (we'll do so during the
4036         // GC). We also call this after finalize_cset() to
4037         // ensure that the CSet has been finalized.
4038         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4039                                  true  /* verify_enqueued_buffers */,
4040                                  false /* verify_thread_buffers */,
4041                                  true  /* verify_fingers */);
4042 
4043         if (_hr_printer.is_active()) {
4044           HeapRegion* hr = g1_policy()->collection_set();
4045           while (hr != NULL) {
4046             G1HRPrinter::RegionType type;
4047             if (!hr->is_young()) {
4048               type = G1HRPrinter::Old;
4049             } else if (hr->is_survivor()) {
4050               type = G1HRPrinter::Survivor;
4051             } else {
4052               type = G1HRPrinter::Eden;
4053             }
4054             _hr_printer.cset(hr);
4055             hr = hr->next_in_collection_set();
4056           }
4057         }
4058 
4059 #ifdef ASSERT
4060         VerifyCSetClosure cl;
4061         collection_set_iterate(&cl);
4062 #endif // ASSERT
4063 
4064         setup_surviving_young_words();
4065 
4066         // Initialize the GC alloc regions.
4067         init_gc_alloc_regions(evacuation_info);
4068 
4069         // Actually do the work...
4070         evacuate_collection_set(evacuation_info);
4071 
4072         // We do this to mainly verify the per-thread SATB buffers
4073         // (which have been filtered by now) since we didn't verify
4074         // them earlier. No point in re-checking the stacks / enqueued
4075         // buffers given that the CSet has not changed since last time
4076         // we checked.
4077         _cm->verify_no_cset_oops(false /* verify_stacks */,
4078                                  false /* verify_enqueued_buffers */,
4079                                  true  /* verify_thread_buffers */,
4080                                  true  /* verify_fingers */);
4081 
4082         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4083         g1_policy()->clear_collection_set();
4084 
4085         cleanup_surviving_young_words();
4086 
4087         // Start a new incremental collection set for the next pause.
4088         g1_policy()->start_incremental_cset_building();
4089 
4090         // Clear the _cset_fast_test bitmap in anticipation of adding
4091         // regions to the incremental collection set for the next
4092         // evacuation pause.
4093         clear_cset_fast_test();
4094 
4095         _young_list->reset_sampled_info();
4096 
4097         // Don't check the whole heap at this point as the
4098         // GC alloc regions from this pause have been tagged
4099         // as survivors and moved on to the survivor list.
4100         // Survivor regions will fail the !is_young() check.
4101         assert(check_young_list_empty(false /* check_heap */),
4102           "young list should be empty");
4103 
4104 #if YOUNG_LIST_VERBOSE
4105         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4106         _young_list->print();
4107 #endif // YOUNG_LIST_VERBOSE
4108 
4109         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4110                                              _young_list->first_survivor_region(),
4111                                              _young_list->last_survivor_region());
4112 
4113         _young_list->reset_auxilary_lists();
4114 
4115         if (evacuation_failed()) {
4116           _summary_bytes_used = recalculate_used();
4117           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4118           for (uint i = 0; i < n_queues; i++) {
4119             if (_evacuation_failed_info_array[i].has_failed()) {
4120               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4121             }
4122           }
4123         } else {
4124           // The "used" of the the collection set have already been subtracted
4125           // when they were freed.  Add in the bytes evacuated.
4126           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4127         }
4128 
4129         if (g1_policy()->during_initial_mark_pause()) {
4130           // We have to do this before we notify the CM threads that
4131           // they can start working to make sure that all the
4132           // appropriate initialization is done on the CM object.
4133           concurrent_mark()->checkpointRootsInitialPost();
4134           set_marking_started();
4135           // Note that we don't actually trigger the CM thread at
4136           // this point. We do that later when we're sure that
4137           // the current thread has completed its logging output.
4138         }
4139 
4140         allocate_dummy_regions();
4141 
4142 #if YOUNG_LIST_VERBOSE
4143         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4144         _young_list->print();
4145         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4146 #endif // YOUNG_LIST_VERBOSE
4147 
4148         init_mutator_alloc_region();
4149 
4150         {
4151           size_t expand_bytes = g1_policy()->expansion_amount();
4152           if (expand_bytes > 0) {
4153             size_t bytes_before = capacity();
4154             // No need for an ergo verbose message here,
4155             // expansion_amount() does this when it returns a value > 0.
4156             if (!expand(expand_bytes)) {
4157               // We failed to expand the heap so let's verify that
4158               // committed/uncommitted amount match the backing store
4159               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4160               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4161             }
4162           }
4163         }
4164 
4165         // We redo the verification but now wrt to the new CSet which
4166         // has just got initialized after the previous CSet was freed.
4167         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4168                                  true  /* verify_enqueued_buffers */,
4169                                  true  /* verify_thread_buffers */,
4170                                  true  /* verify_fingers */);
4171         _cm->note_end_of_gc();
4172 
4173         // This timing is only used by the ergonomics to handle our pause target.
4174         // It is unclear why this should not include the full pause. We will
4175         // investigate this in CR 7178365.
4176         double sample_end_time_sec = os::elapsedTime();
4177         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4178         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4179 
4180         MemoryService::track_memory_usage();
4181 
4182         // In prepare_for_verify() below we'll need to scan the deferred
4183         // update buffers to bring the RSets up-to-date if
4184         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4185         // the update buffers we'll probably need to scan cards on the
4186         // regions we just allocated to (i.e., the GC alloc
4187         // regions). However, during the last GC we called
4188         // set_saved_mark() on all the GC alloc regions, so card
4189         // scanning might skip the [saved_mark_word()...top()] area of
4190         // those regions (i.e., the area we allocated objects into
4191         // during the last GC). But it shouldn't. Given that
4192         // saved_mark_word() is conditional on whether the GC time stamp
4193         // on the region is current or not, by incrementing the GC time
4194         // stamp here we invalidate all the GC time stamps on all the
4195         // regions and saved_mark_word() will simply return top() for
4196         // all the regions. This is a nicer way of ensuring this rather
4197         // than iterating over the regions and fixing them. In fact, the
4198         // GC time stamp increment here also ensures that
4199         // saved_mark_word() will return top() between pauses, i.e.,
4200         // during concurrent refinement. So we don't need the
4201         // is_gc_active() check to decided which top to use when
4202         // scanning cards (see CR 7039627).
4203         increment_gc_time_stamp();
4204 
4205         verify_after_gc();
4206 
4207         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4208         ref_processor_stw()->verify_no_references_recorded();
4209 
4210         // CM reference discovery will be re-enabled if necessary.
4211       }
4212 
4213       // We should do this after we potentially expand the heap so
4214       // that all the COMMIT events are generated before the end GC
4215       // event, and after we retire the GC alloc regions so that all
4216       // RETIRE events are generated before the end GC event.
4217       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4218 
4219       if (mark_in_progress()) {
4220         concurrent_mark()->update_g1_committed();
4221       }
4222 
4223 #ifdef TRACESPINNING
4224       ParallelTaskTerminator::print_termination_counts();
4225 #endif
4226 
4227       gc_epilogue(false);
4228     }
4229 
4230     // Print the remainder of the GC log output.
4231     log_gc_footer(os::elapsedTime() - pause_start_sec);
4232 
4233     // It is not yet to safe to tell the concurrent mark to
4234     // start as we have some optional output below. We don't want the
4235     // output from the concurrent mark thread interfering with this
4236     // logging output either.
4237 
4238     _hrs.verify_optional();
4239     verify_region_sets_optional();
4240 
4241     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4242     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4243 
4244     print_heap_after_gc();
4245     trace_heap_after_gc(_gc_tracer_stw);
4246 
4247     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4248     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4249     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4250     // before any GC notifications are raised.
4251     g1mm()->update_sizes();
4252 
4253     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4254     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4255     _gc_timer_stw->register_gc_end();
4256     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4257   }
4258   // It should now be safe to tell the concurrent mark thread to start
4259   // without its logging output interfering with the logging output
4260   // that came from the pause.
4261 
4262   if (should_start_conc_mark) {
4263     // CAUTION: after the doConcurrentMark() call below,
4264     // the concurrent marking thread(s) could be running
4265     // concurrently with us. Make sure that anything after
4266     // this point does not assume that we are the only GC thread
4267     // running. Note: of course, the actual marking work will
4268     // not start until the safepoint itself is released in
4269     // ConcurrentGCThread::safepoint_desynchronize().
4270     doConcurrentMark();
4271   }
4272 
4273   return true;
4274 }
4275 
4276 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4277 {
4278   size_t gclab_word_size;
4279   switch (purpose) {
4280     case GCAllocForSurvived:
4281       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4282       break;
4283     case GCAllocForTenured:
4284       gclab_word_size = _old_plab_stats.desired_plab_sz();
4285       break;
4286     default:
4287       assert(false, "unknown GCAllocPurpose");
4288       gclab_word_size = _old_plab_stats.desired_plab_sz();
4289       break;
4290   }
4291 
4292   // Prevent humongous PLAB sizes for two reasons:
4293   // * PLABs are allocated using a similar paths as oops, but should
4294   //   never be in a humongous region
4295   // * Allowing humongous PLABs needlessly churns the region free lists
4296   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4297 }
4298 
4299 void G1CollectedHeap::init_mutator_alloc_region() {
4300   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4301   _mutator_alloc_region.init();
4302 }
4303 
4304 void G1CollectedHeap::release_mutator_alloc_region() {
4305   _mutator_alloc_region.release();
4306   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4307 }
4308 
4309 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4310   assert_at_safepoint(true /* should_be_vm_thread */);
4311 
4312   _survivor_gc_alloc_region.init();
4313   _old_gc_alloc_region.init();
4314   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4315   _retained_old_gc_alloc_region = NULL;
4316 
4317   // We will discard the current GC alloc region if:
4318   // a) it's in the collection set (it can happen!),
4319   // b) it's already full (no point in using it),
4320   // c) it's empty (this means that it was emptied during
4321   // a cleanup and it should be on the free list now), or
4322   // d) it's humongous (this means that it was emptied
4323   // during a cleanup and was added to the free list, but
4324   // has been subsequently used to allocate a humongous
4325   // object that may be less than the region size).
4326   if (retained_region != NULL &&
4327       !retained_region->in_collection_set() &&
4328       !(retained_region->top() == retained_region->end()) &&
4329       !retained_region->is_empty() &&
4330       !retained_region->isHumongous()) {
4331     retained_region->set_saved_mark();
4332     // The retained region was added to the old region set when it was
4333     // retired. We have to remove it now, since we don't allow regions
4334     // we allocate to in the region sets. We'll re-add it later, when
4335     // it's retired again.
4336     _old_set.remove(retained_region);
4337     bool during_im = g1_policy()->during_initial_mark_pause();
4338     retained_region->note_start_of_copying(during_im);
4339     _old_gc_alloc_region.set(retained_region);
4340     _hr_printer.reuse(retained_region);
4341     evacuation_info.set_alloc_regions_used_before(retained_region->used());
4342   }
4343 }
4344 
4345 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4346   evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4347                                          _old_gc_alloc_region.count());
4348   _survivor_gc_alloc_region.release();
4349   // If we have an old GC alloc region to release, we'll save it in
4350   // _retained_old_gc_alloc_region. If we don't
4351   // _retained_old_gc_alloc_region will become NULL. This is what we
4352   // want either way so no reason to check explicitly for either
4353   // condition.
4354   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4355 
4356   if (ResizePLAB) {
4357     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4358     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4359   }
4360 }
4361 
4362 void G1CollectedHeap::abandon_gc_alloc_regions() {
4363   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4364   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4365   _retained_old_gc_alloc_region = NULL;
4366 }
4367 
4368 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4369   _drain_in_progress = false;
4370   set_evac_failure_closure(cl);
4371   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4372 }
4373 
4374 void G1CollectedHeap::finalize_for_evac_failure() {
4375   assert(_evac_failure_scan_stack != NULL &&
4376          _evac_failure_scan_stack->length() == 0,
4377          "Postcondition");
4378   assert(!_drain_in_progress, "Postcondition");
4379   delete _evac_failure_scan_stack;
4380   _evac_failure_scan_stack = NULL;
4381 }
4382 
4383 void G1CollectedHeap::remove_self_forwarding_pointers() {
4384   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4385 
4386   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4387 
4388   if (G1CollectedHeap::use_parallel_gc_threads()) {
4389     set_par_threads();
4390     workers()->run_task(&rsfp_task);
4391     set_par_threads(0);
4392   } else {
4393     rsfp_task.work(0);
4394   }
4395 
4396   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4397 
4398   // Reset the claim values in the regions in the collection set.
4399   reset_cset_heap_region_claim_values();
4400 
4401   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4402 
4403   // Now restore saved marks, if any.
4404   assert(_objs_with_preserved_marks.size() ==
4405             _preserved_marks_of_objs.size(), "Both or none.");
4406   while (!_objs_with_preserved_marks.is_empty()) {
4407     oop obj = _objs_with_preserved_marks.pop();
4408     markOop m = _preserved_marks_of_objs.pop();
4409     obj->set_mark(m);
4410   }
4411   _objs_with_preserved_marks.clear(true);
4412   _preserved_marks_of_objs.clear(true);
4413 }
4414 
4415 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4416   _evac_failure_scan_stack->push(obj);
4417 }
4418 
4419 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4420   assert(_evac_failure_scan_stack != NULL, "precondition");
4421 
4422   while (_evac_failure_scan_stack->length() > 0) {
4423      oop obj = _evac_failure_scan_stack->pop();
4424      _evac_failure_closure->set_region(heap_region_containing(obj));
4425      obj->oop_iterate_backwards(_evac_failure_closure);
4426   }
4427 }
4428 
4429 oop
4430 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4431                                                oop old) {
4432   assert(obj_in_cs(old),
4433          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4434                  (HeapWord*) old));
4435   markOop m = old->mark();
4436   oop forward_ptr = old->forward_to_atomic(old);
4437   if (forward_ptr == NULL) {
4438     // Forward-to-self succeeded.
4439     assert(_par_scan_state != NULL, "par scan state");
4440     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4441     uint queue_num = _par_scan_state->queue_num();
4442 
4443     _evacuation_failed = true;
4444     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4445     if (_evac_failure_closure != cl) {
4446       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4447       assert(!_drain_in_progress,
4448              "Should only be true while someone holds the lock.");
4449       // Set the global evac-failure closure to the current thread's.
4450       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4451       set_evac_failure_closure(cl);
4452       // Now do the common part.
4453       handle_evacuation_failure_common(old, m);
4454       // Reset to NULL.
4455       set_evac_failure_closure(NULL);
4456     } else {
4457       // The lock is already held, and this is recursive.
4458       assert(_drain_in_progress, "This should only be the recursive case.");
4459       handle_evacuation_failure_common(old, m);
4460     }
4461     return old;
4462   } else {
4463     // Forward-to-self failed. Either someone else managed to allocate
4464     // space for this object (old != forward_ptr) or they beat us in
4465     // self-forwarding it (old == forward_ptr).
4466     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4467            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4468                    "should not be in the CSet",
4469                    (HeapWord*) old, (HeapWord*) forward_ptr));
4470     return forward_ptr;
4471   }
4472 }
4473 
4474 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4475   preserve_mark_if_necessary(old, m);
4476 
4477   HeapRegion* r = heap_region_containing(old);
4478   if (!r->evacuation_failed()) {
4479     r->set_evacuation_failed(true);
4480     _hr_printer.evac_failure(r);
4481   }
4482 
4483   push_on_evac_failure_scan_stack(old);
4484 
4485   if (!_drain_in_progress) {
4486     // prevent recursion in copy_to_survivor_space()
4487     _drain_in_progress = true;
4488     drain_evac_failure_scan_stack();
4489     _drain_in_progress = false;
4490   }
4491 }
4492 
4493 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4494   assert(evacuation_failed(), "Oversaving!");
4495   // We want to call the "for_promotion_failure" version only in the
4496   // case of a promotion failure.
4497   if (m->must_be_preserved_for_promotion_failure(obj)) {
4498     _objs_with_preserved_marks.push(obj);
4499     _preserved_marks_of_objs.push(m);
4500   }
4501 }
4502 
4503 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4504                                                   size_t word_size) {
4505   if (purpose == GCAllocForSurvived) {
4506     HeapWord* result = survivor_attempt_allocation(word_size);
4507     if (result != NULL) {
4508       return result;
4509     } else {
4510       // Let's try to allocate in the old gen in case we can fit the
4511       // object there.
4512       return old_attempt_allocation(word_size);
4513     }
4514   } else {
4515     assert(purpose ==  GCAllocForTenured, "sanity");
4516     HeapWord* result = old_attempt_allocation(word_size);
4517     if (result != NULL) {
4518       return result;
4519     } else {
4520       // Let's try to allocate in the survivors in case we can fit the
4521       // object there.
4522       return survivor_attempt_allocation(word_size);
4523     }
4524   }
4525 
4526   ShouldNotReachHere();
4527   // Trying to keep some compilers happy.
4528   return NULL;
4529 }
4530 
4531 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4532   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4533 
4534 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4535   : _g1h(g1h),
4536     _refs(g1h->task_queue(queue_num)),
4537     _dcq(&g1h->dirty_card_queue_set()),
4538     _ct_bs(g1h->g1_barrier_set()),
4539     _g1_rem(g1h->g1_rem_set()),
4540     _hash_seed(17), _queue_num(queue_num),
4541     _term_attempts(0),
4542     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4543     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4544     _age_table(false),
4545     _strong_roots_time(0), _term_time(0),
4546     _alloc_buffer_waste(0), _undo_waste(0) {
4547   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4548   // we "sacrifice" entry 0 to keep track of surviving bytes for
4549   // non-young regions (where the age is -1)
4550   // We also add a few elements at the beginning and at the end in
4551   // an attempt to eliminate cache contention
4552   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4553   uint array_length = PADDING_ELEM_NUM +
4554                       real_length +
4555                       PADDING_ELEM_NUM;
4556   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4557   if (_surviving_young_words_base == NULL)
4558     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4559                           "Not enough space for young surv histo.");
4560   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4561   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4562 
4563   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4564   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4565 
4566   _start = os::elapsedTime();
4567 }
4568 
4569 void
4570 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4571 {
4572   st->print_raw_cr("GC Termination Stats");
4573   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4574                    " ------waste (KiB)------");
4575   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4576                    "  total   alloc    undo");
4577   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4578                    " ------- ------- -------");
4579 }
4580 
4581 void
4582 G1ParScanThreadState::print_termination_stats(int i,
4583                                               outputStream* const st) const
4584 {
4585   const double elapsed_ms = elapsed_time() * 1000.0;
4586   const double s_roots_ms = strong_roots_time() * 1000.0;
4587   const double term_ms    = term_time() * 1000.0;
4588   st->print_cr("%3d %9.2f %9.2f %6.2f "
4589                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4590                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4591                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4592                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4593                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4594                alloc_buffer_waste() * HeapWordSize / K,
4595                undo_waste() * HeapWordSize / K);
4596 }
4597 
4598 #ifdef ASSERT
4599 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4600   assert(ref != NULL, "invariant");
4601   assert(UseCompressedOops, "sanity");
4602   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4603   oop p = oopDesc::load_decode_heap_oop(ref);
4604   assert(_g1h->is_in_g1_reserved(p),
4605          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4606   return true;
4607 }
4608 
4609 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4610   assert(ref != NULL, "invariant");
4611   if (has_partial_array_mask(ref)) {
4612     // Must be in the collection set--it's already been copied.
4613     oop p = clear_partial_array_mask(ref);
4614     assert(_g1h->obj_in_cs(p),
4615            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4616   } else {
4617     oop p = oopDesc::load_decode_heap_oop(ref);
4618     assert(_g1h->is_in_g1_reserved(p),
4619            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4620   }
4621   return true;
4622 }
4623 
4624 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4625   if (ref.is_narrow()) {
4626     return verify_ref((narrowOop*) ref);
4627   } else {
4628     return verify_ref((oop*) ref);
4629   }
4630 }
4631 #endif // ASSERT
4632 
4633 void G1ParScanThreadState::trim_queue() {
4634   assert(_evac_cl != NULL, "not set");
4635   assert(_evac_failure_cl != NULL, "not set");
4636   assert(_partial_scan_cl != NULL, "not set");
4637 
4638   StarTask ref;
4639   do {
4640     // Drain the overflow stack first, so other threads can steal.
4641     while (refs()->pop_overflow(ref)) {
4642       deal_with_reference(ref);
4643     }
4644 
4645     while (refs()->pop_local(ref)) {
4646       deal_with_reference(ref);
4647     }
4648   } while (!refs()->is_empty());
4649 }
4650 
4651 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4652                                      G1ParScanThreadState* par_scan_state) :
4653   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4654   _par_scan_state(par_scan_state),
4655   _worker_id(par_scan_state->queue_num()),
4656   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4657   _mark_in_progress(_g1->mark_in_progress()) { }
4658 
4659 template <G1Barrier barrier, bool do_mark_object>
4660 void G1ParCopyClosure<barrier, do_mark_object>::mark_object(oop obj) {
4661 #ifdef ASSERT
4662   HeapRegion* hr = _g1->heap_region_containing(obj);
4663   assert(hr != NULL, "sanity");
4664   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4665 #endif // ASSERT
4666 
4667   // We know that the object is not moving so it's safe to read its size.
4668   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4669 }
4670 
4671 template <G1Barrier barrier, bool do_mark_object>
4672 void G1ParCopyClosure<barrier, do_mark_object>
4673   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4674 #ifdef ASSERT
4675   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4676   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4677   assert(from_obj != to_obj, "should not be self-forwarded");
4678 
4679   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4680   assert(from_hr != NULL, "sanity");
4681   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4682 
4683   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4684   assert(to_hr != NULL, "sanity");
4685   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4686 #endif // ASSERT
4687 
4688   // The object might be in the process of being copied by another
4689   // worker so we cannot trust that its to-space image is
4690   // well-formed. So we have to read its size from its from-space
4691   // image which we know should not be changing.
4692   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4693 }
4694 
4695 template <G1Barrier barrier, bool do_mark_object>
4696 oop G1ParCopyClosure<barrier, do_mark_object>
4697   ::copy_to_survivor_space(oop old) {
4698   size_t word_sz = old->size();
4699   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4700   // +1 to make the -1 indexes valid...
4701   int       young_index = from_region->young_index_in_cset()+1;
4702   assert( (from_region->is_young() && young_index >  0) ||
4703          (!from_region->is_young() && young_index == 0), "invariant" );
4704   G1CollectorPolicy* g1p = _g1->g1_policy();
4705   markOop m = old->mark();
4706   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4707                                            : m->age();
4708   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4709                                                              word_sz);
4710   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4711 #ifndef PRODUCT
4712   // Should this evacuation fail?
4713   if (_g1->evacuation_should_fail()) {
4714     if (obj_ptr != NULL) {
4715       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4716       obj_ptr = NULL;
4717     }
4718   }
4719 #endif // !PRODUCT
4720 
4721   if (obj_ptr == NULL) {
4722     // This will either forward-to-self, or detect that someone else has
4723     // installed a forwarding pointer.
4724     return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4725   }
4726 
4727   oop obj = oop(obj_ptr);
4728 
4729   // We're going to allocate linearly, so might as well prefetch ahead.
4730   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4731 
4732   oop forward_ptr = old->forward_to_atomic(obj);
4733   if (forward_ptr == NULL) {
4734     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4735     if (g1p->track_object_age(alloc_purpose)) {
4736       // We could simply do obj->incr_age(). However, this causes a
4737       // performance issue. obj->incr_age() will first check whether
4738       // the object has a displaced mark by checking its mark word;
4739       // getting the mark word from the new location of the object
4740       // stalls. So, given that we already have the mark word and we
4741       // are about to install it anyway, it's better to increase the
4742       // age on the mark word, when the object does not have a
4743       // displaced mark word. We're not expecting many objects to have
4744       // a displaced marked word, so that case is not optimized
4745       // further (it could be...) and we simply call obj->incr_age().
4746 
4747       if (m->has_displaced_mark_helper()) {
4748         // in this case, we have to install the mark word first,
4749         // otherwise obj looks to be forwarded (the old mark word,
4750         // which contains the forward pointer, was copied)
4751         obj->set_mark(m);
4752         obj->incr_age();
4753       } else {
4754         m = m->incr_age();
4755         obj->set_mark(m);
4756       }
4757       _par_scan_state->age_table()->add(obj, word_sz);
4758     } else {
4759       obj->set_mark(m);
4760     }
4761 
4762     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4763     surv_young_words[young_index] += word_sz;
4764 
4765     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4766       // We keep track of the next start index in the length field of
4767       // the to-space object. The actual length can be found in the
4768       // length field of the from-space object.
4769       arrayOop(obj)->set_length(0);
4770       oop* old_p = set_partial_array_mask(old);
4771       _par_scan_state->push_on_queue(old_p);
4772     } else {
4773       // No point in using the slower heap_region_containing() method,
4774       // given that we know obj is in the heap.
4775       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4776       obj->oop_iterate_backwards(&_scanner);
4777     }
4778   } else {
4779     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4780     obj = forward_ptr;
4781   }
4782   return obj;
4783 }
4784 
4785 template <class T>
4786 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4787   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4788     _scanned_klass->record_modified_oops();
4789   }
4790 }
4791 
4792 template <G1Barrier barrier, bool do_mark_object>
4793 template <class T>
4794 void G1ParCopyClosure<barrier, do_mark_object>
4795 ::do_oop_work(T* p) {
4796   oop obj = oopDesc::load_decode_heap_oop(p);
4797 
4798   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4799 
4800   // here the null check is implicit in the cset_fast_test() test
4801   if (_g1->in_cset_fast_test(obj)) {
4802     oop forwardee;
4803     if (obj->is_forwarded()) {
4804       forwardee = obj->forwardee();
4805     } else {
4806       forwardee = copy_to_survivor_space(obj);
4807     }
4808     assert(forwardee != NULL, "forwardee should not be NULL");
4809     oopDesc::encode_store_heap_oop(p, forwardee);
4810     if (do_mark_object && forwardee != obj) {
4811       // If the object is self-forwarded we don't need to explicitly
4812       // mark it, the evacuation failure protocol will do so.
4813       mark_forwarded_object(obj, forwardee);
4814     }
4815 
4816     if (barrier == G1BarrierKlass) {
4817       do_klass_barrier(p, forwardee);
4818     }
4819   } else {
4820     // The object is not in collection set. If we're a root scanning
4821     // closure during an initial mark pause (i.e. do_mark_object will
4822     // be true) then attempt to mark the object.
4823     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4824       mark_object(obj);
4825     }
4826   }
4827 
4828   if (barrier == G1BarrierEvac && obj != NULL) {
4829     _par_scan_state->update_rs(_from, p, _worker_id);
4830   }
4831 }
4832 
4833 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4834 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4835 
4836 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4837   assert(has_partial_array_mask(p), "invariant");
4838   oop from_obj = clear_partial_array_mask(p);
4839 
4840   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4841   assert(from_obj->is_objArray(), "must be obj array");
4842   objArrayOop from_obj_array = objArrayOop(from_obj);
4843   // The from-space object contains the real length.
4844   int length                 = from_obj_array->length();
4845 
4846   assert(from_obj->is_forwarded(), "must be forwarded");
4847   oop to_obj                 = from_obj->forwardee();
4848   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4849   objArrayOop to_obj_array   = objArrayOop(to_obj);
4850   // We keep track of the next start index in the length field of the
4851   // to-space object.
4852   int next_index             = to_obj_array->length();
4853   assert(0 <= next_index && next_index < length,
4854          err_msg("invariant, next index: %d, length: %d", next_index, length));
4855 
4856   int start                  = next_index;
4857   int end                    = length;
4858   int remainder              = end - start;
4859   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4860   if (remainder > 2 * ParGCArrayScanChunk) {
4861     end = start + ParGCArrayScanChunk;
4862     to_obj_array->set_length(end);
4863     // Push the remainder before we process the range in case another
4864     // worker has run out of things to do and can steal it.
4865     oop* from_obj_p = set_partial_array_mask(from_obj);
4866     _par_scan_state->push_on_queue(from_obj_p);
4867   } else {
4868     assert(length == end, "sanity");
4869     // We'll process the final range for this object. Restore the length
4870     // so that the heap remains parsable in case of evacuation failure.
4871     to_obj_array->set_length(end);
4872   }
4873   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4874   // Process indexes [start,end). It will also process the header
4875   // along with the first chunk (i.e., the chunk with start == 0).
4876   // Note that at this point the length field of to_obj_array is not
4877   // correct given that we are using it to keep track of the next
4878   // start index. oop_iterate_range() (thankfully!) ignores the length
4879   // field and only relies on the start / end parameters.  It does
4880   // however return the size of the object which will be incorrect. So
4881   // we have to ignore it even if we wanted to use it.
4882   to_obj_array->oop_iterate_range(&_scanner, start, end);
4883 }
4884 
4885 class G1ParEvacuateFollowersClosure : public VoidClosure {
4886 protected:
4887   G1CollectedHeap*              _g1h;
4888   G1ParScanThreadState*         _par_scan_state;
4889   RefToScanQueueSet*            _queues;
4890   ParallelTaskTerminator*       _terminator;
4891 
4892   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4893   RefToScanQueueSet*      queues()         { return _queues; }
4894   ParallelTaskTerminator* terminator()     { return _terminator; }
4895 
4896 public:
4897   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4898                                 G1ParScanThreadState* par_scan_state,
4899                                 RefToScanQueueSet* queues,
4900                                 ParallelTaskTerminator* terminator)
4901     : _g1h(g1h), _par_scan_state(par_scan_state),
4902       _queues(queues), _terminator(terminator) {}
4903 
4904   void do_void();
4905 
4906 private:
4907   inline bool offer_termination();
4908 };
4909 
4910 bool G1ParEvacuateFollowersClosure::offer_termination() {
4911   G1ParScanThreadState* const pss = par_scan_state();
4912   pss->start_term_time();
4913   const bool res = terminator()->offer_termination();
4914   pss->end_term_time();
4915   return res;
4916 }
4917 
4918 void G1ParEvacuateFollowersClosure::do_void() {
4919   StarTask stolen_task;
4920   G1ParScanThreadState* const pss = par_scan_state();
4921   pss->trim_queue();
4922 
4923   do {
4924     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4925       assert(pss->verify_task(stolen_task), "sanity");
4926       if (stolen_task.is_narrow()) {
4927         pss->deal_with_reference((narrowOop*) stolen_task);
4928       } else {
4929         pss->deal_with_reference((oop*) stolen_task);
4930       }
4931 
4932       // We've just processed a reference and we might have made
4933       // available new entries on the queues. So we have to make sure
4934       // we drain the queues as necessary.
4935       pss->trim_queue();
4936     }
4937   } while (!offer_termination());
4938 
4939   pss->retire_alloc_buffers();
4940 }
4941 
4942 class G1KlassScanClosure : public KlassClosure {
4943  G1ParCopyHelper* _closure;
4944  bool             _process_only_dirty;
4945  int              _count;
4946  public:
4947   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4948       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4949   void do_klass(Klass* klass) {
4950     // If the klass has not been dirtied we know that there's
4951     // no references into  the young gen and we can skip it.
4952    if (!_process_only_dirty || klass->has_modified_oops()) {
4953       // Clean the klass since we're going to scavenge all the metadata.
4954       klass->clear_modified_oops();
4955 
4956       // Tell the closure that this klass is the Klass to scavenge
4957       // and is the one to dirty if oops are left pointing into the young gen.
4958       _closure->set_scanned_klass(klass);
4959 
4960       klass->oops_do(_closure);
4961 
4962       _closure->set_scanned_klass(NULL);
4963     }
4964     _count++;
4965   }
4966 };
4967 
4968 class G1ParTask : public AbstractGangTask {
4969 protected:
4970   G1CollectedHeap*       _g1h;
4971   RefToScanQueueSet      *_queues;
4972   ParallelTaskTerminator _terminator;
4973   uint _n_workers;
4974 
4975   Mutex _stats_lock;
4976   Mutex* stats_lock() { return &_stats_lock; }
4977 
4978   size_t getNCards() {
4979     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4980       / G1BlockOffsetSharedArray::N_bytes;
4981   }
4982 
4983 public:
4984   G1ParTask(G1CollectedHeap* g1h,
4985             RefToScanQueueSet *task_queues)
4986     : AbstractGangTask("G1 collection"),
4987       _g1h(g1h),
4988       _queues(task_queues),
4989       _terminator(0, _queues),
4990       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4991   {}
4992 
4993   RefToScanQueueSet* queues() { return _queues; }
4994 
4995   RefToScanQueue *work_queue(int i) {
4996     return queues()->queue(i);
4997   }
4998 
4999   ParallelTaskTerminator* terminator() { return &_terminator; }
5000 
5001   virtual void set_for_termination(int active_workers) {
5002     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5003     // in the young space (_par_seq_tasks) in the G1 heap
5004     // for SequentialSubTasksDone.
5005     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5006     // both of which need setting by set_n_termination().
5007     _g1h->SharedHeap::set_n_termination(active_workers);
5008     _g1h->set_n_termination(active_workers);
5009     terminator()->reset_for_reuse(active_workers);
5010     _n_workers = active_workers;
5011   }
5012 
5013   void work(uint worker_id) {
5014     if (worker_id >= _n_workers) return;  // no work needed this round
5015 
5016     double start_time_ms = os::elapsedTime() * 1000.0;
5017     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5018 
5019     {
5020       ResourceMark rm;
5021       HandleMark   hm;
5022 
5023       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
5024 
5025       G1ParScanThreadState            pss(_g1h, worker_id);
5026       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
5027       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5028       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
5029 
5030       pss.set_evac_closure(&scan_evac_cl);
5031       pss.set_evac_failure_closure(&evac_failure_cl);
5032       pss.set_partial_scan_closure(&partial_scan_cl);
5033 
5034       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
5035       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
5036 
5037       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5038       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5039 
5040       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
5041       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5042       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5043 
5044       OopClosure*                    scan_root_cl = &only_scan_root_cl;
5045       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
5046 
5047       if (_g1h->g1_policy()->during_initial_mark_pause()) {
5048         // We also need to mark copied objects.
5049         scan_root_cl = &scan_mark_root_cl;
5050         scan_klasses_cl = &scan_mark_klasses_cl_s;
5051       }
5052 
5053       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
5054 
5055       // Don't scan the scavengable methods in the code cache as part
5056       // of strong root scanning. The code roots that point into a
5057       // region in the collection set are scanned when we scan the
5058       // region's RSet.
5059       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5060 
5061       pss.start_strong_roots();
5062       _g1h->g1_process_strong_roots(/* is scavenging */ true,
5063                                     SharedHeap::ScanningOption(so),
5064                                     scan_root_cl,
5065                                     &push_heap_rs_cl,
5066                                     scan_klasses_cl,
5067                                     worker_id);
5068       pss.end_strong_roots();
5069 
5070       {
5071         double start = os::elapsedTime();
5072         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5073         evac.do_void();
5074         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5075         double term_ms = pss.term_time()*1000.0;
5076         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5077         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5078       }
5079       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5080       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5081 
5082       if (ParallelGCVerbose) {
5083         MutexLocker x(stats_lock());
5084         pss.print_termination_stats(worker_id);
5085       }
5086 
5087       assert(pss.refs()->is_empty(), "should be empty");
5088 
5089       // Close the inner scope so that the ResourceMark and HandleMark
5090       // destructors are executed here and are included as part of the
5091       // "GC Worker Time".
5092     }
5093 
5094     double end_time_ms = os::elapsedTime() * 1000.0;
5095     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5096   }
5097 };
5098 
5099 // *** Common G1 Evacuation Stuff
5100 
5101 // This method is run in a GC worker.
5102 
5103 void
5104 G1CollectedHeap::
5105 g1_process_strong_roots(bool is_scavenging,
5106                         ScanningOption so,
5107                         OopClosure* scan_non_heap_roots,
5108                         OopsInHeapRegionClosure* scan_rs,
5109                         G1KlassScanClosure* scan_klasses,
5110                         int worker_i) {
5111 
5112   // First scan the strong roots
5113   double ext_roots_start = os::elapsedTime();
5114   double closure_app_time_sec = 0.0;
5115 
5116   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5117 
5118   assert(so & SO_AllCodeCache || scan_rs != NULL, "must scan code roots somehow");
5119   // Walk the code cache/strong code roots w/o buffering, because StarTask
5120   // cannot handle unaligned oop locations.
5121   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5122 
5123   process_strong_roots(false, // no scoping; this is parallel code
5124                        so,
5125                        &buf_scan_non_heap_roots,
5126                        &eager_scan_code_roots,
5127                        scan_klasses
5128                        );
5129 
5130   // Now the CM ref_processor roots.
5131   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5132     // We need to treat the discovered reference lists of the
5133     // concurrent mark ref processor as roots and keep entries
5134     // (which are added by the marking threads) on them live
5135     // until they can be processed at the end of marking.
5136     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5137   }
5138 
5139   // Finish up any enqueued closure apps (attributed as object copy time).
5140   buf_scan_non_heap_roots.done();
5141 
5142   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5143 
5144   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5145 
5146   double ext_root_time_ms =
5147     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5148 
5149   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5150 
5151   // During conc marking we have to filter the per-thread SATB buffers
5152   // to make sure we remove any oops into the CSet (which will show up
5153   // as implicitly live).
5154   double satb_filtering_ms = 0.0;
5155   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5156     if (mark_in_progress()) {
5157       double satb_filter_start = os::elapsedTime();
5158 
5159       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5160 
5161       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5162     }
5163   }
5164   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5165 
5166   // If this is an initial mark pause, and we're not scanning
5167   // the entire code cache, we need to mark the oops in the
5168   // strong code root lists for the regions that are not in
5169   // the collection set.
5170   // Note all threads participate in this set of root tasks.
5171   double mark_strong_code_roots_ms = 0.0;
5172   if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5173     double mark_strong_roots_start = os::elapsedTime();
5174     mark_strong_code_roots(worker_i);
5175     mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5176   }
5177   g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5178 
5179   // Now scan the complement of the collection set.
5180   if (scan_rs != NULL) {
5181     g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5182   }
5183   _process_strong_tasks->all_tasks_completed();
5184 }
5185 
5186 void
5187 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5188   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5189   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5190 }
5191 
5192 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5193 private:
5194   BoolObjectClosure* _is_alive;
5195   int _initial_string_table_size;
5196   int _initial_symbol_table_size;
5197 
5198   bool  _process_strings;
5199   int _strings_processed;
5200   int _strings_removed;
5201 
5202   bool  _process_symbols;
5203   int _symbols_processed;
5204   int _symbols_removed;
5205 
5206   bool _do_in_parallel;
5207 public:
5208   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5209     AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5210     _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5211     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5212     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5213 
5214     _initial_string_table_size = StringTable::the_table()->table_size();
5215     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5216     if (process_strings) {
5217       StringTable::clear_parallel_claimed_index();
5218     }
5219     if (process_symbols) {
5220       SymbolTable::clear_parallel_claimed_index();
5221     }
5222   }
5223 
5224   ~G1StringSymbolTableUnlinkTask() {
5225     guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5226               err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5227                       StringTable::parallel_claimed_index(), _initial_string_table_size));
5228     guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5229               err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5230                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5231   }
5232 
5233   void work(uint worker_id) {
5234     if (_do_in_parallel) {
5235       int strings_processed = 0;
5236       int strings_removed = 0;
5237       int symbols_processed = 0;
5238       int symbols_removed = 0;
5239       if (_process_strings) {
5240         StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5241         Atomic::add(strings_processed, &_strings_processed);
5242         Atomic::add(strings_removed, &_strings_removed);
5243       }
5244       if (_process_symbols) {
5245         SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5246         Atomic::add(symbols_processed, &_symbols_processed);
5247         Atomic::add(symbols_removed, &_symbols_removed);
5248       }
5249     } else {
5250       if (_process_strings) {
5251         StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5252       }
5253       if (_process_symbols) {
5254         SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5255       }
5256     }
5257   }
5258 
5259   size_t strings_processed() const { return (size_t)_strings_processed; }
5260   size_t strings_removed()   const { return (size_t)_strings_removed; }
5261 
5262   size_t symbols_processed() const { return (size_t)_symbols_processed; }
5263   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
5264 };
5265 
5266 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5267                                                      bool process_strings, bool process_symbols) {
5268   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5269                    _g1h->workers()->active_workers() : 1);
5270 
5271   G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5272   if (G1CollectedHeap::use_parallel_gc_threads()) {
5273     set_par_threads(n_workers);
5274     workers()->run_task(&g1_unlink_task);
5275     set_par_threads(0);
5276   } else {
5277     g1_unlink_task.work(0);
5278   }
5279   if (G1TraceStringSymbolTableScrubbing) {
5280     gclog_or_tty->print_cr("Cleaned string and symbol table, "
5281                            "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5282                            "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5283                            g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5284                            g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5285   }
5286 }
5287 
5288 // Weak Reference Processing support
5289 
5290 // An always "is_alive" closure that is used to preserve referents.
5291 // If the object is non-null then it's alive.  Used in the preservation
5292 // of referent objects that are pointed to by reference objects
5293 // discovered by the CM ref processor.
5294 class G1AlwaysAliveClosure: public BoolObjectClosure {
5295   G1CollectedHeap* _g1;
5296 public:
5297   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5298   bool do_object_b(oop p) {
5299     if (p != NULL) {
5300       return true;
5301     }
5302     return false;
5303   }
5304 };
5305 
5306 bool G1STWIsAliveClosure::do_object_b(oop p) {
5307   // An object is reachable if it is outside the collection set,
5308   // or is inside and copied.
5309   return !_g1->obj_in_cs(p) || p->is_forwarded();
5310 }
5311 
5312 // Non Copying Keep Alive closure
5313 class G1KeepAliveClosure: public OopClosure {
5314   G1CollectedHeap* _g1;
5315 public:
5316   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5317   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5318   void do_oop(      oop* p) {
5319     oop obj = *p;
5320 
5321     if (_g1->obj_in_cs(obj)) {
5322       assert( obj->is_forwarded(), "invariant" );
5323       *p = obj->forwardee();
5324     }
5325   }
5326 };
5327 
5328 // Copying Keep Alive closure - can be called from both
5329 // serial and parallel code as long as different worker
5330 // threads utilize different G1ParScanThreadState instances
5331 // and different queues.
5332 
5333 class G1CopyingKeepAliveClosure: public OopClosure {
5334   G1CollectedHeap*         _g1h;
5335   OopClosure*              _copy_non_heap_obj_cl;
5336   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5337   G1ParScanThreadState*    _par_scan_state;
5338 
5339 public:
5340   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5341                             OopClosure* non_heap_obj_cl,
5342                             OopsInHeapRegionClosure* metadata_obj_cl,
5343                             G1ParScanThreadState* pss):
5344     _g1h(g1h),
5345     _copy_non_heap_obj_cl(non_heap_obj_cl),
5346     _copy_metadata_obj_cl(metadata_obj_cl),
5347     _par_scan_state(pss)
5348   {}
5349 
5350   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5351   virtual void do_oop(      oop* p) { do_oop_work(p); }
5352 
5353   template <class T> void do_oop_work(T* p) {
5354     oop obj = oopDesc::load_decode_heap_oop(p);
5355 
5356     if (_g1h->obj_in_cs(obj)) {
5357       // If the referent object has been forwarded (either copied
5358       // to a new location or to itself in the event of an
5359       // evacuation failure) then we need to update the reference
5360       // field and, if both reference and referent are in the G1
5361       // heap, update the RSet for the referent.
5362       //
5363       // If the referent has not been forwarded then we have to keep
5364       // it alive by policy. Therefore we have copy the referent.
5365       //
5366       // If the reference field is in the G1 heap then we can push
5367       // on the PSS queue. When the queue is drained (after each
5368       // phase of reference processing) the object and it's followers
5369       // will be copied, the reference field set to point to the
5370       // new location, and the RSet updated. Otherwise we need to
5371       // use the the non-heap or metadata closures directly to copy
5372       // the referent object and update the pointer, while avoiding
5373       // updating the RSet.
5374 
5375       if (_g1h->is_in_g1_reserved(p)) {
5376         _par_scan_state->push_on_queue(p);
5377       } else {
5378         assert(!ClassLoaderDataGraph::contains((address)p),
5379                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5380                               PTR_FORMAT, p));
5381           _copy_non_heap_obj_cl->do_oop(p);
5382         }
5383       }
5384     }
5385 };
5386 
5387 // Serial drain queue closure. Called as the 'complete_gc'
5388 // closure for each discovered list in some of the
5389 // reference processing phases.
5390 
5391 class G1STWDrainQueueClosure: public VoidClosure {
5392 protected:
5393   G1CollectedHeap* _g1h;
5394   G1ParScanThreadState* _par_scan_state;
5395 
5396   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5397 
5398 public:
5399   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5400     _g1h(g1h),
5401     _par_scan_state(pss)
5402   { }
5403 
5404   void do_void() {
5405     G1ParScanThreadState* const pss = par_scan_state();
5406     pss->trim_queue();
5407   }
5408 };
5409 
5410 // Parallel Reference Processing closures
5411 
5412 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5413 // processing during G1 evacuation pauses.
5414 
5415 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5416 private:
5417   G1CollectedHeap*   _g1h;
5418   RefToScanQueueSet* _queues;
5419   FlexibleWorkGang*  _workers;
5420   int                _active_workers;
5421 
5422 public:
5423   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5424                         FlexibleWorkGang* workers,
5425                         RefToScanQueueSet *task_queues,
5426                         int n_workers) :
5427     _g1h(g1h),
5428     _queues(task_queues),
5429     _workers(workers),
5430     _active_workers(n_workers)
5431   {
5432     assert(n_workers > 0, "shouldn't call this otherwise");
5433   }
5434 
5435   // Executes the given task using concurrent marking worker threads.
5436   virtual void execute(ProcessTask& task);
5437   virtual void execute(EnqueueTask& task);
5438 };
5439 
5440 // Gang task for possibly parallel reference processing
5441 
5442 class G1STWRefProcTaskProxy: public AbstractGangTask {
5443   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5444   ProcessTask&     _proc_task;
5445   G1CollectedHeap* _g1h;
5446   RefToScanQueueSet *_task_queues;
5447   ParallelTaskTerminator* _terminator;
5448 
5449 public:
5450   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5451                      G1CollectedHeap* g1h,
5452                      RefToScanQueueSet *task_queues,
5453                      ParallelTaskTerminator* terminator) :
5454     AbstractGangTask("Process reference objects in parallel"),
5455     _proc_task(proc_task),
5456     _g1h(g1h),
5457     _task_queues(task_queues),
5458     _terminator(terminator)
5459   {}
5460 
5461   virtual void work(uint worker_id) {
5462     // The reference processing task executed by a single worker.
5463     ResourceMark rm;
5464     HandleMark   hm;
5465 
5466     G1STWIsAliveClosure is_alive(_g1h);
5467 
5468     G1ParScanThreadState pss(_g1h, worker_id);
5469 
5470     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5471     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5472     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5473 
5474     pss.set_evac_closure(&scan_evac_cl);
5475     pss.set_evac_failure_closure(&evac_failure_cl);
5476     pss.set_partial_scan_closure(&partial_scan_cl);
5477 
5478     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5479     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5480 
5481     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5482     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5483 
5484     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5485     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5486 
5487     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5488       // We also need to mark copied objects.
5489       copy_non_heap_cl = &copy_mark_non_heap_cl;
5490       copy_metadata_cl = &copy_mark_metadata_cl;
5491     }
5492 
5493     // Keep alive closure.
5494     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5495 
5496     // Complete GC closure
5497     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5498 
5499     // Call the reference processing task's work routine.
5500     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5501 
5502     // Note we cannot assert that the refs array is empty here as not all
5503     // of the processing tasks (specifically phase2 - pp2_work) execute
5504     // the complete_gc closure (which ordinarily would drain the queue) so
5505     // the queue may not be empty.
5506   }
5507 };
5508 
5509 // Driver routine for parallel reference processing.
5510 // Creates an instance of the ref processing gang
5511 // task and has the worker threads execute it.
5512 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5513   assert(_workers != NULL, "Need parallel worker threads.");
5514 
5515   ParallelTaskTerminator terminator(_active_workers, _queues);
5516   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5517 
5518   _g1h->set_par_threads(_active_workers);
5519   _workers->run_task(&proc_task_proxy);
5520   _g1h->set_par_threads(0);
5521 }
5522 
5523 // Gang task for parallel reference enqueueing.
5524 
5525 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5526   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5527   EnqueueTask& _enq_task;
5528 
5529 public:
5530   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5531     AbstractGangTask("Enqueue reference objects in parallel"),
5532     _enq_task(enq_task)
5533   { }
5534 
5535   virtual void work(uint worker_id) {
5536     _enq_task.work(worker_id);
5537   }
5538 };
5539 
5540 // Driver routine for parallel reference enqueueing.
5541 // Creates an instance of the ref enqueueing gang
5542 // task and has the worker threads execute it.
5543 
5544 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5545   assert(_workers != NULL, "Need parallel worker threads.");
5546 
5547   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5548 
5549   _g1h->set_par_threads(_active_workers);
5550   _workers->run_task(&enq_task_proxy);
5551   _g1h->set_par_threads(0);
5552 }
5553 
5554 // End of weak reference support closures
5555 
5556 // Abstract task used to preserve (i.e. copy) any referent objects
5557 // that are in the collection set and are pointed to by reference
5558 // objects discovered by the CM ref processor.
5559 
5560 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5561 protected:
5562   G1CollectedHeap* _g1h;
5563   RefToScanQueueSet      *_queues;
5564   ParallelTaskTerminator _terminator;
5565   uint _n_workers;
5566 
5567 public:
5568   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5569     AbstractGangTask("ParPreserveCMReferents"),
5570     _g1h(g1h),
5571     _queues(task_queues),
5572     _terminator(workers, _queues),
5573     _n_workers(workers)
5574   { }
5575 
5576   void work(uint worker_id) {
5577     ResourceMark rm;
5578     HandleMark   hm;
5579 
5580     G1ParScanThreadState            pss(_g1h, worker_id);
5581     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5582     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5583     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5584 
5585     pss.set_evac_closure(&scan_evac_cl);
5586     pss.set_evac_failure_closure(&evac_failure_cl);
5587     pss.set_partial_scan_closure(&partial_scan_cl);
5588 
5589     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5590 
5591 
5592     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5593     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5594 
5595     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5596     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5597 
5598     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5599     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5600 
5601     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5602       // We also need to mark copied objects.
5603       copy_non_heap_cl = &copy_mark_non_heap_cl;
5604       copy_metadata_cl = &copy_mark_metadata_cl;
5605     }
5606 
5607     // Is alive closure
5608     G1AlwaysAliveClosure always_alive(_g1h);
5609 
5610     // Copying keep alive closure. Applied to referent objects that need
5611     // to be copied.
5612     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5613 
5614     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5615 
5616     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5617     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5618 
5619     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5620     // So this must be true - but assert just in case someone decides to
5621     // change the worker ids.
5622     assert(0 <= worker_id && worker_id < limit, "sanity");
5623     assert(!rp->discovery_is_atomic(), "check this code");
5624 
5625     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5626     for (uint idx = worker_id; idx < limit; idx += stride) {
5627       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5628 
5629       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5630       while (iter.has_next()) {
5631         // Since discovery is not atomic for the CM ref processor, we
5632         // can see some null referent objects.
5633         iter.load_ptrs(DEBUG_ONLY(true));
5634         oop ref = iter.obj();
5635 
5636         // This will filter nulls.
5637         if (iter.is_referent_alive()) {
5638           iter.make_referent_alive();
5639         }
5640         iter.move_to_next();
5641       }
5642     }
5643 
5644     // Drain the queue - which may cause stealing
5645     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5646     drain_queue.do_void();
5647     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5648     assert(pss.refs()->is_empty(), "should be");
5649   }
5650 };
5651 
5652 // Weak Reference processing during an evacuation pause (part 1).
5653 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5654   double ref_proc_start = os::elapsedTime();
5655 
5656   ReferenceProcessor* rp = _ref_processor_stw;
5657   assert(rp->discovery_enabled(), "should have been enabled");
5658 
5659   // Any reference objects, in the collection set, that were 'discovered'
5660   // by the CM ref processor should have already been copied (either by
5661   // applying the external root copy closure to the discovered lists, or
5662   // by following an RSet entry).
5663   //
5664   // But some of the referents, that are in the collection set, that these
5665   // reference objects point to may not have been copied: the STW ref
5666   // processor would have seen that the reference object had already
5667   // been 'discovered' and would have skipped discovering the reference,
5668   // but would not have treated the reference object as a regular oop.
5669   // As a result the copy closure would not have been applied to the
5670   // referent object.
5671   //
5672   // We need to explicitly copy these referent objects - the references
5673   // will be processed at the end of remarking.
5674   //
5675   // We also need to do this copying before we process the reference
5676   // objects discovered by the STW ref processor in case one of these
5677   // referents points to another object which is also referenced by an
5678   // object discovered by the STW ref processor.
5679 
5680   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5681            no_of_gc_workers == workers()->active_workers(),
5682            "Need to reset active GC workers");
5683 
5684   set_par_threads(no_of_gc_workers);
5685   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5686                                                  no_of_gc_workers,
5687                                                  _task_queues);
5688 
5689   if (G1CollectedHeap::use_parallel_gc_threads()) {
5690     workers()->run_task(&keep_cm_referents);
5691   } else {
5692     keep_cm_referents.work(0);
5693   }
5694 
5695   set_par_threads(0);
5696 
5697   // Closure to test whether a referent is alive.
5698   G1STWIsAliveClosure is_alive(this);
5699 
5700   // Even when parallel reference processing is enabled, the processing
5701   // of JNI refs is serial and performed serially by the current thread
5702   // rather than by a worker. The following PSS will be used for processing
5703   // JNI refs.
5704 
5705   // Use only a single queue for this PSS.
5706   G1ParScanThreadState pss(this, 0);
5707 
5708   // We do not embed a reference processor in the copying/scanning
5709   // closures while we're actually processing the discovered
5710   // reference objects.
5711   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5712   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5713   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5714 
5715   pss.set_evac_closure(&scan_evac_cl);
5716   pss.set_evac_failure_closure(&evac_failure_cl);
5717   pss.set_partial_scan_closure(&partial_scan_cl);
5718 
5719   assert(pss.refs()->is_empty(), "pre-condition");
5720 
5721   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5722   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5723 
5724   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5725   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5726 
5727   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5728   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5729 
5730   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5731     // We also need to mark copied objects.
5732     copy_non_heap_cl = &copy_mark_non_heap_cl;
5733     copy_metadata_cl = &copy_mark_metadata_cl;
5734   }
5735 
5736   // Keep alive closure.
5737   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5738 
5739   // Serial Complete GC closure
5740   G1STWDrainQueueClosure drain_queue(this, &pss);
5741 
5742   // Setup the soft refs policy...
5743   rp->setup_policy(false);
5744 
5745   ReferenceProcessorStats stats;
5746   if (!rp->processing_is_mt()) {
5747     // Serial reference processing...
5748     stats = rp->process_discovered_references(&is_alive,
5749                                               &keep_alive,
5750                                               &drain_queue,
5751                                               NULL,
5752                                               _gc_timer_stw);
5753   } else {
5754     // Parallel reference processing
5755     assert(rp->num_q() == no_of_gc_workers, "sanity");
5756     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5757 
5758     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5759     stats = rp->process_discovered_references(&is_alive,
5760                                               &keep_alive,
5761                                               &drain_queue,
5762                                               &par_task_executor,
5763                                               _gc_timer_stw);
5764   }
5765 
5766   _gc_tracer_stw->report_gc_reference_stats(stats);
5767   // We have completed copying any necessary live referent objects
5768   // (that were not copied during the actual pause) so we can
5769   // retire any active alloc buffers
5770   pss.retire_alloc_buffers();
5771   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5772 
5773   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5774   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5775 }
5776 
5777 // Weak Reference processing during an evacuation pause (part 2).
5778 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5779   double ref_enq_start = os::elapsedTime();
5780 
5781   ReferenceProcessor* rp = _ref_processor_stw;
5782   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5783 
5784   // Now enqueue any remaining on the discovered lists on to
5785   // the pending list.
5786   if (!rp->processing_is_mt()) {
5787     // Serial reference processing...
5788     rp->enqueue_discovered_references();
5789   } else {
5790     // Parallel reference enqueueing
5791 
5792     assert(no_of_gc_workers == workers()->active_workers(),
5793            "Need to reset active workers");
5794     assert(rp->num_q() == no_of_gc_workers, "sanity");
5795     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5796 
5797     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5798     rp->enqueue_discovered_references(&par_task_executor);
5799   }
5800 
5801   rp->verify_no_references_recorded();
5802   assert(!rp->discovery_enabled(), "should have been disabled");
5803 
5804   // FIXME
5805   // CM's reference processing also cleans up the string and symbol tables.
5806   // Should we do that here also? We could, but it is a serial operation
5807   // and could significantly increase the pause time.
5808 
5809   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5810   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5811 }
5812 
5813 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5814   _expand_heap_after_alloc_failure = true;
5815   _evacuation_failed = false;
5816 
5817   // Should G1EvacuationFailureALot be in effect for this GC?
5818   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5819 
5820   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5821 
5822   // Disable the hot card cache.
5823   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5824   hot_card_cache->reset_hot_cache_claimed_index();
5825   hot_card_cache->set_use_cache(false);
5826 
5827   uint n_workers;
5828   if (G1CollectedHeap::use_parallel_gc_threads()) {
5829     n_workers =
5830       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5831                                      workers()->active_workers(),
5832                                      Threads::number_of_non_daemon_threads());
5833     assert(UseDynamicNumberOfGCThreads ||
5834            n_workers == workers()->total_workers(),
5835            "If not dynamic should be using all the  workers");
5836     workers()->set_active_workers(n_workers);
5837     set_par_threads(n_workers);
5838   } else {
5839     assert(n_par_threads() == 0,
5840            "Should be the original non-parallel value");
5841     n_workers = 1;
5842   }
5843 
5844   G1ParTask g1_par_task(this, _task_queues);
5845 
5846   init_for_evac_failure(NULL);
5847 
5848   rem_set()->prepare_for_younger_refs_iterate(true);
5849 
5850   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5851   double start_par_time_sec = os::elapsedTime();
5852   double end_par_time_sec;
5853 
5854   {
5855     StrongRootsScope srs(this);
5856 
5857     if (G1CollectedHeap::use_parallel_gc_threads()) {
5858       // The individual threads will set their evac-failure closures.
5859       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5860       // These tasks use ShareHeap::_process_strong_tasks
5861       assert(UseDynamicNumberOfGCThreads ||
5862              workers()->active_workers() == workers()->total_workers(),
5863              "If not dynamic should be using all the  workers");
5864       workers()->run_task(&g1_par_task);
5865     } else {
5866       g1_par_task.set_for_termination(n_workers);
5867       g1_par_task.work(0);
5868     }
5869     end_par_time_sec = os::elapsedTime();
5870 
5871     // Closing the inner scope will execute the destructor
5872     // for the StrongRootsScope object. We record the current
5873     // elapsed time before closing the scope so that time
5874     // taken for the SRS destructor is NOT included in the
5875     // reported parallel time.
5876   }
5877 
5878   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5879   g1_policy()->phase_times()->record_par_time(par_time_ms);
5880 
5881   double code_root_fixup_time_ms =
5882         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5883   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5884 
5885   set_par_threads(0);
5886 
5887   // Process any discovered reference objects - we have
5888   // to do this _before_ we retire the GC alloc regions
5889   // as we may have to copy some 'reachable' referent
5890   // objects (and their reachable sub-graphs) that were
5891   // not copied during the pause.
5892   process_discovered_references(n_workers);
5893 
5894   // Weak root processing.
5895   {
5896     G1STWIsAliveClosure is_alive(this);
5897     G1KeepAliveClosure keep_alive(this);
5898     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5899   }
5900 
5901   release_gc_alloc_regions(n_workers, evacuation_info);
5902   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5903 
5904   // Reset and re-enable the hot card cache.
5905   // Note the counts for the cards in the regions in the
5906   // collection set are reset when the collection set is freed.
5907   hot_card_cache->reset_hot_cache();
5908   hot_card_cache->set_use_cache(true);
5909 
5910   // Migrate the strong code roots attached to each region in
5911   // the collection set. Ideally we would like to do this
5912   // after we have finished the scanning/evacuation of the
5913   // strong code roots for a particular heap region.
5914   migrate_strong_code_roots();
5915 
5916   if (g1_policy()->during_initial_mark_pause()) {
5917     // Reset the claim values set during marking the strong code roots
5918     reset_heap_region_claim_values();
5919   }
5920 
5921   finalize_for_evac_failure();
5922 
5923   if (evacuation_failed()) {
5924     remove_self_forwarding_pointers();
5925 
5926     // Reset the G1EvacuationFailureALot counters and flags
5927     // Note: the values are reset only when an actual
5928     // evacuation failure occurs.
5929     NOT_PRODUCT(reset_evacuation_should_fail();)
5930   }
5931 
5932   // Enqueue any remaining references remaining on the STW
5933   // reference processor's discovered lists. We need to do
5934   // this after the card table is cleaned (and verified) as
5935   // the act of enqueueing entries on to the pending list
5936   // will log these updates (and dirty their associated
5937   // cards). We need these updates logged to update any
5938   // RSets.
5939   enqueue_discovered_references(n_workers);
5940 
5941   if (G1DeferredRSUpdate) {
5942     RedirtyLoggedCardTableEntryFastClosure redirty;
5943     dirty_card_queue_set().set_closure(&redirty);
5944     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5945 
5946     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5947     dcq.merge_bufferlists(&dirty_card_queue_set());
5948     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5949   }
5950   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5951 }
5952 
5953 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5954                                      size_t* pre_used,
5955                                      FreeRegionList* free_list,
5956                                      OldRegionSet* old_proxy_set,
5957                                      HumongousRegionSet* humongous_proxy_set,
5958                                      HRRSCleanupTask* hrrs_cleanup_task,
5959                                      bool par) {
5960   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5961     if (hr->isHumongous()) {
5962       assert(hr->startsHumongous(), "we should only see starts humongous");
5963       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5964     } else {
5965       _old_set.remove_with_proxy(hr, old_proxy_set);
5966       free_region(hr, pre_used, free_list, par);
5967     }
5968   } else {
5969     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5970   }
5971 }
5972 
5973 void G1CollectedHeap::free_region(HeapRegion* hr,
5974                                   size_t* pre_used,
5975                                   FreeRegionList* free_list,
5976                                   bool par) {
5977   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5978   assert(!hr->is_empty(), "the region should not be empty");
5979   assert(free_list != NULL, "pre-condition");
5980 
5981   // Clear the card counts for this region.
5982   // Note: we only need to do this if the region is not young
5983   // (since we don't refine cards in young regions).
5984   if (!hr->is_young()) {
5985     _cg1r->hot_card_cache()->reset_card_counts(hr);
5986   }
5987   *pre_used += hr->used();
5988   hr->hr_clear(par, true /* clear_space */);
5989   free_list->add_as_head(hr);
5990 }
5991 
5992 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5993                                      size_t* pre_used,
5994                                      FreeRegionList* free_list,
5995                                      HumongousRegionSet* humongous_proxy_set,
5996                                      bool par) {
5997   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5998   assert(free_list != NULL, "pre-condition");
5999   assert(humongous_proxy_set != NULL, "pre-condition");
6000 
6001   size_t hr_used = hr->used();
6002   size_t hr_capacity = hr->capacity();
6003   size_t hr_pre_used = 0;
6004   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
6005   // We need to read this before we make the region non-humongous,
6006   // otherwise the information will be gone.
6007   uint last_index = hr->last_hc_index();
6008   hr->set_notHumongous();
6009   free_region(hr, &hr_pre_used, free_list, par);
6010 
6011   uint i = hr->hrs_index() + 1;
6012   while (i < last_index) {
6013     HeapRegion* curr_hr = region_at(i);
6014     assert(curr_hr->continuesHumongous(), "invariant");
6015     curr_hr->set_notHumongous();
6016     free_region(curr_hr, &hr_pre_used, free_list, par);
6017     i += 1;
6018   }
6019   assert(hr_pre_used == hr_used,
6020          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
6021                  "should be the same", hr_pre_used, hr_used));
6022   *pre_used += hr_pre_used;
6023 }
6024 
6025 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
6026                                        FreeRegionList* free_list,
6027                                        OldRegionSet* old_proxy_set,
6028                                        HumongousRegionSet* humongous_proxy_set,
6029                                        bool par) {
6030   if (pre_used > 0) {
6031     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
6032     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
6033     assert(_summary_bytes_used >= pre_used,
6034            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
6035                    "should be >= pre_used: "SIZE_FORMAT,
6036                    _summary_bytes_used, pre_used));
6037     _summary_bytes_used -= pre_used;
6038   }
6039   if (free_list != NULL && !free_list->is_empty()) {
6040     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6041     _free_list.add_as_head(free_list);
6042   }
6043   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
6044     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6045     _old_set.update_from_proxy(old_proxy_set);
6046   }
6047   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
6048     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6049     _humongous_set.update_from_proxy(humongous_proxy_set);
6050   }
6051 }
6052 
6053 class G1ParCleanupCTTask : public AbstractGangTask {
6054   G1SATBCardTableModRefBS* _ct_bs;
6055   G1CollectedHeap* _g1h;
6056   HeapRegion* volatile _su_head;
6057 public:
6058   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6059                      G1CollectedHeap* g1h) :
6060     AbstractGangTask("G1 Par Cleanup CT Task"),
6061     _ct_bs(ct_bs), _g1h(g1h) { }
6062 
6063   void work(uint worker_id) {
6064     HeapRegion* r;
6065     while (r = _g1h->pop_dirty_cards_region()) {
6066       clear_cards(r);
6067     }
6068   }
6069 
6070   void clear_cards(HeapRegion* r) {
6071     // Cards of the survivors should have already been dirtied.
6072     if (!r->is_survivor()) {
6073       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6074     }
6075   }
6076 };
6077 
6078 #ifndef PRODUCT
6079 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6080   G1CollectedHeap* _g1h;
6081   G1SATBCardTableModRefBS* _ct_bs;
6082 public:
6083   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6084     : _g1h(g1h), _ct_bs(ct_bs) { }
6085   virtual bool doHeapRegion(HeapRegion* r) {
6086     if (r->is_survivor()) {
6087       _g1h->verify_dirty_region(r);
6088     } else {
6089       _g1h->verify_not_dirty_region(r);
6090     }
6091     return false;
6092   }
6093 };
6094 
6095 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6096   // All of the region should be clean.
6097   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6098   MemRegion mr(hr->bottom(), hr->end());
6099   ct_bs->verify_not_dirty_region(mr);
6100 }
6101 
6102 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6103   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
6104   // dirty allocated blocks as they allocate them. The thread that
6105   // retires each region and replaces it with a new one will do a
6106   // maximal allocation to fill in [pre_dummy_top(),end()] but will
6107   // not dirty that area (one less thing to have to do while holding
6108   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6109   // is dirty.
6110   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6111   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6112   if (hr->is_young()) {
6113     ct_bs->verify_g1_young_region(mr);
6114   } else {
6115     ct_bs->verify_dirty_region(mr);
6116   }
6117 }
6118 
6119 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6120   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6121   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6122     verify_dirty_region(hr);
6123   }
6124 }
6125 
6126 void G1CollectedHeap::verify_dirty_young_regions() {
6127   verify_dirty_young_list(_young_list->first_region());
6128 }
6129 #endif
6130 
6131 void G1CollectedHeap::cleanUpCardTable() {
6132   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6133   double start = os::elapsedTime();
6134 
6135   {
6136     // Iterate over the dirty cards region list.
6137     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6138 
6139     if (G1CollectedHeap::use_parallel_gc_threads()) {
6140       set_par_threads();
6141       workers()->run_task(&cleanup_task);
6142       set_par_threads(0);
6143     } else {
6144       while (_dirty_cards_region_list) {
6145         HeapRegion* r = _dirty_cards_region_list;
6146         cleanup_task.clear_cards(r);
6147         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6148         if (_dirty_cards_region_list == r) {
6149           // The last region.
6150           _dirty_cards_region_list = NULL;
6151         }
6152         r->set_next_dirty_cards_region(NULL);
6153       }
6154     }
6155 #ifndef PRODUCT
6156     if (G1VerifyCTCleanup || VerifyAfterGC) {
6157       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6158       heap_region_iterate(&cleanup_verifier);
6159     }
6160 #endif
6161   }
6162 
6163   double elapsed = os::elapsedTime() - start;
6164   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6165 }
6166 
6167 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6168   size_t pre_used = 0;
6169   FreeRegionList local_free_list("Local List for CSet Freeing");
6170 
6171   double young_time_ms     = 0.0;
6172   double non_young_time_ms = 0.0;
6173 
6174   // Since the collection set is a superset of the the young list,
6175   // all we need to do to clear the young list is clear its
6176   // head and length, and unlink any young regions in the code below
6177   _young_list->clear();
6178 
6179   G1CollectorPolicy* policy = g1_policy();
6180 
6181   double start_sec = os::elapsedTime();
6182   bool non_young = true;
6183 
6184   HeapRegion* cur = cs_head;
6185   int age_bound = -1;
6186   size_t rs_lengths = 0;
6187 
6188   while (cur != NULL) {
6189     assert(!is_on_master_free_list(cur), "sanity");
6190     if (non_young) {
6191       if (cur->is_young()) {
6192         double end_sec = os::elapsedTime();
6193         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6194         non_young_time_ms += elapsed_ms;
6195 
6196         start_sec = os::elapsedTime();
6197         non_young = false;
6198       }
6199     } else {
6200       if (!cur->is_young()) {
6201         double end_sec = os::elapsedTime();
6202         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6203         young_time_ms += elapsed_ms;
6204 
6205         start_sec = os::elapsedTime();
6206         non_young = true;
6207       }
6208     }
6209 
6210     rs_lengths += cur->rem_set()->occupied();
6211 
6212     HeapRegion* next = cur->next_in_collection_set();
6213     assert(cur->in_collection_set(), "bad CS");
6214     cur->set_next_in_collection_set(NULL);
6215     cur->set_in_collection_set(false);
6216 
6217     if (cur->is_young()) {
6218       int index = cur->young_index_in_cset();
6219       assert(index != -1, "invariant");
6220       assert((uint) index < policy->young_cset_region_length(), "invariant");
6221       size_t words_survived = _surviving_young_words[index];
6222       cur->record_surv_words_in_group(words_survived);
6223 
6224       // At this point the we have 'popped' cur from the collection set
6225       // (linked via next_in_collection_set()) but it is still in the
6226       // young list (linked via next_young_region()). Clear the
6227       // _next_young_region field.
6228       cur->set_next_young_region(NULL);
6229     } else {
6230       int index = cur->young_index_in_cset();
6231       assert(index == -1, "invariant");
6232     }
6233 
6234     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6235             (!cur->is_young() && cur->young_index_in_cset() == -1),
6236             "invariant" );
6237 
6238     if (!cur->evacuation_failed()) {
6239       MemRegion used_mr = cur->used_region();
6240 
6241       // And the region is empty.
6242       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6243       free_region(cur, &pre_used, &local_free_list, false /* par */);
6244     } else {
6245       cur->uninstall_surv_rate_group();
6246       if (cur->is_young()) {
6247         cur->set_young_index_in_cset(-1);
6248       }
6249       cur->set_not_young();
6250       cur->set_evacuation_failed(false);
6251       // The region is now considered to be old.
6252       _old_set.add(cur);
6253       evacuation_info.increment_collectionset_used_after(cur->used());
6254     }
6255     cur = next;
6256   }
6257 
6258   evacuation_info.set_regions_freed(local_free_list.length());
6259   policy->record_max_rs_lengths(rs_lengths);
6260   policy->cset_regions_freed();
6261 
6262   double end_sec = os::elapsedTime();
6263   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6264 
6265   if (non_young) {
6266     non_young_time_ms += elapsed_ms;
6267   } else {
6268     young_time_ms += elapsed_ms;
6269   }
6270 
6271   update_sets_after_freeing_regions(pre_used, &local_free_list,
6272                                     NULL /* old_proxy_set */,
6273                                     NULL /* humongous_proxy_set */,
6274                                     false /* par */);
6275   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6276   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6277 }
6278 
6279 // This routine is similar to the above but does not record
6280 // any policy statistics or update free lists; we are abandoning
6281 // the current incremental collection set in preparation of a
6282 // full collection. After the full GC we will start to build up
6283 // the incremental collection set again.
6284 // This is only called when we're doing a full collection
6285 // and is immediately followed by the tearing down of the young list.
6286 
6287 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6288   HeapRegion* cur = cs_head;
6289 
6290   while (cur != NULL) {
6291     HeapRegion* next = cur->next_in_collection_set();
6292     assert(cur->in_collection_set(), "bad CS");
6293     cur->set_next_in_collection_set(NULL);
6294     cur->set_in_collection_set(false);
6295     cur->set_young_index_in_cset(-1);
6296     cur = next;
6297   }
6298 }
6299 
6300 void G1CollectedHeap::set_free_regions_coming() {
6301   if (G1ConcRegionFreeingVerbose) {
6302     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6303                            "setting free regions coming");
6304   }
6305 
6306   assert(!free_regions_coming(), "pre-condition");
6307   _free_regions_coming = true;
6308 }
6309 
6310 void G1CollectedHeap::reset_free_regions_coming() {
6311   assert(free_regions_coming(), "pre-condition");
6312 
6313   {
6314     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6315     _free_regions_coming = false;
6316     SecondaryFreeList_lock->notify_all();
6317   }
6318 
6319   if (G1ConcRegionFreeingVerbose) {
6320     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6321                            "reset free regions coming");
6322   }
6323 }
6324 
6325 void G1CollectedHeap::wait_while_free_regions_coming() {
6326   // Most of the time we won't have to wait, so let's do a quick test
6327   // first before we take the lock.
6328   if (!free_regions_coming()) {
6329     return;
6330   }
6331 
6332   if (G1ConcRegionFreeingVerbose) {
6333     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6334                            "waiting for free regions");
6335   }
6336 
6337   {
6338     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6339     while (free_regions_coming()) {
6340       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6341     }
6342   }
6343 
6344   if (G1ConcRegionFreeingVerbose) {
6345     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6346                            "done waiting for free regions");
6347   }
6348 }
6349 
6350 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6351   assert(heap_lock_held_for_gc(),
6352               "the heap lock should already be held by or for this thread");
6353   _young_list->push_region(hr);
6354 }
6355 
6356 class NoYoungRegionsClosure: public HeapRegionClosure {
6357 private:
6358   bool _success;
6359 public:
6360   NoYoungRegionsClosure() : _success(true) { }
6361   bool doHeapRegion(HeapRegion* r) {
6362     if (r->is_young()) {
6363       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6364                              r->bottom(), r->end());
6365       _success = false;
6366     }
6367     return false;
6368   }
6369   bool success() { return _success; }
6370 };
6371 
6372 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6373   bool ret = _young_list->check_list_empty(check_sample);
6374 
6375   if (check_heap) {
6376     NoYoungRegionsClosure closure;
6377     heap_region_iterate(&closure);
6378     ret = ret && closure.success();
6379   }
6380 
6381   return ret;
6382 }
6383 
6384 class TearDownRegionSetsClosure : public HeapRegionClosure {
6385 private:
6386   OldRegionSet *_old_set;
6387 
6388 public:
6389   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6390 
6391   bool doHeapRegion(HeapRegion* r) {
6392     if (r->is_empty()) {
6393       // We ignore empty regions, we'll empty the free list afterwards
6394     } else if (r->is_young()) {
6395       // We ignore young regions, we'll empty the young list afterwards
6396     } else if (r->isHumongous()) {
6397       // We ignore humongous regions, we're not tearing down the
6398       // humongous region set
6399     } else {
6400       // The rest should be old
6401       _old_set->remove(r);
6402     }
6403     return false;
6404   }
6405 
6406   ~TearDownRegionSetsClosure() {
6407     assert(_old_set->is_empty(), "post-condition");
6408   }
6409 };
6410 
6411 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6412   assert_at_safepoint(true /* should_be_vm_thread */);
6413 
6414   if (!free_list_only) {
6415     TearDownRegionSetsClosure cl(&_old_set);
6416     heap_region_iterate(&cl);
6417 
6418     // Need to do this after the heap iteration to be able to
6419     // recognize the young regions and ignore them during the iteration.
6420     _young_list->empty_list();
6421   }
6422   _free_list.remove_all();
6423 }
6424 
6425 class RebuildRegionSetsClosure : public HeapRegionClosure {
6426 private:
6427   bool            _free_list_only;
6428   OldRegionSet*   _old_set;
6429   FreeRegionList* _free_list;
6430   size_t          _total_used;
6431 
6432 public:
6433   RebuildRegionSetsClosure(bool free_list_only,
6434                            OldRegionSet* old_set, FreeRegionList* free_list) :
6435     _free_list_only(free_list_only),
6436     _old_set(old_set), _free_list(free_list), _total_used(0) {
6437     assert(_free_list->is_empty(), "pre-condition");
6438     if (!free_list_only) {
6439       assert(_old_set->is_empty(), "pre-condition");
6440     }
6441   }
6442 
6443   bool doHeapRegion(HeapRegion* r) {
6444     if (r->continuesHumongous()) {
6445       return false;
6446     }
6447 
6448     if (r->is_empty()) {
6449       // Add free regions to the free list
6450       _free_list->add_as_tail(r);
6451     } else if (!_free_list_only) {
6452       assert(!r->is_young(), "we should not come across young regions");
6453 
6454       if (r->isHumongous()) {
6455         // We ignore humongous regions, we left the humongous set unchanged
6456       } else {
6457         // The rest should be old, add them to the old set
6458         _old_set->add(r);
6459       }
6460       _total_used += r->used();
6461     }
6462 
6463     return false;
6464   }
6465 
6466   size_t total_used() {
6467     return _total_used;
6468   }
6469 };
6470 
6471 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6472   assert_at_safepoint(true /* should_be_vm_thread */);
6473 
6474   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6475   heap_region_iterate(&cl);
6476 
6477   if (!free_list_only) {
6478     _summary_bytes_used = cl.total_used();
6479   }
6480   assert(_summary_bytes_used == recalculate_used(),
6481          err_msg("inconsistent _summary_bytes_used, "
6482                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6483                  _summary_bytes_used, recalculate_used()));
6484 }
6485 
6486 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6487   _refine_cte_cl->set_concurrent(concurrent);
6488 }
6489 
6490 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6491   HeapRegion* hr = heap_region_containing(p);
6492   if (hr == NULL) {
6493     return false;
6494   } else {
6495     return hr->is_in(p);
6496   }
6497 }
6498 
6499 // Methods for the mutator alloc region
6500 
6501 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6502                                                       bool force) {
6503   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6504   assert(!force || g1_policy()->can_expand_young_list(),
6505          "if force is true we should be able to expand the young list");
6506   bool young_list_full = g1_policy()->is_young_list_full();
6507   if (force || !young_list_full) {
6508     HeapRegion* new_alloc_region = new_region(word_size,
6509                                               false /* do_expand */);
6510     if (new_alloc_region != NULL) {
6511       set_region_short_lived_locked(new_alloc_region);
6512       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6513       return new_alloc_region;
6514     }
6515   }
6516   return NULL;
6517 }
6518 
6519 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6520                                                   size_t allocated_bytes) {
6521   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6522   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6523 
6524   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6525   _summary_bytes_used += allocated_bytes;
6526   _hr_printer.retire(alloc_region);
6527   // We update the eden sizes here, when the region is retired,
6528   // instead of when it's allocated, since this is the point that its
6529   // used space has been recored in _summary_bytes_used.
6530   g1mm()->update_eden_size();
6531 }
6532 
6533 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6534                                                     bool force) {
6535   return _g1h->new_mutator_alloc_region(word_size, force);
6536 }
6537 
6538 void G1CollectedHeap::set_par_threads() {
6539   // Don't change the number of workers.  Use the value previously set
6540   // in the workgroup.
6541   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6542   uint n_workers = workers()->active_workers();
6543   assert(UseDynamicNumberOfGCThreads ||
6544            n_workers == workers()->total_workers(),
6545       "Otherwise should be using the total number of workers");
6546   if (n_workers == 0) {
6547     assert(false, "Should have been set in prior evacuation pause.");
6548     n_workers = ParallelGCThreads;
6549     workers()->set_active_workers(n_workers);
6550   }
6551   set_par_threads(n_workers);
6552 }
6553 
6554 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6555                                        size_t allocated_bytes) {
6556   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6557 }
6558 
6559 // Methods for the GC alloc regions
6560 
6561 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6562                                                  uint count,
6563                                                  GCAllocPurpose ap) {
6564   assert(FreeList_lock->owned_by_self(), "pre-condition");
6565 
6566   if (count < g1_policy()->max_regions(ap)) {
6567     HeapRegion* new_alloc_region = new_region(word_size,
6568                                               true /* do_expand */);
6569     if (new_alloc_region != NULL) {
6570       // We really only need to do this for old regions given that we
6571       // should never scan survivors. But it doesn't hurt to do it
6572       // for survivors too.
6573       new_alloc_region->set_saved_mark();
6574       if (ap == GCAllocForSurvived) {
6575         new_alloc_region->set_survivor();
6576         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6577       } else {
6578         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6579       }
6580       bool during_im = g1_policy()->during_initial_mark_pause();
6581       new_alloc_region->note_start_of_copying(during_im);
6582       return new_alloc_region;
6583     } else {
6584       g1_policy()->note_alloc_region_limit_reached(ap);
6585     }
6586   }
6587   return NULL;
6588 }
6589 
6590 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6591                                              size_t allocated_bytes,
6592                                              GCAllocPurpose ap) {
6593   bool during_im = g1_policy()->during_initial_mark_pause();
6594   alloc_region->note_end_of_copying(during_im);
6595   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6596   if (ap == GCAllocForSurvived) {
6597     young_list()->add_survivor_region(alloc_region);
6598   } else {
6599     _old_set.add(alloc_region);
6600   }
6601   _hr_printer.retire(alloc_region);
6602 }
6603 
6604 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6605                                                        bool force) {
6606   assert(!force, "not supported for GC alloc regions");
6607   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6608 }
6609 
6610 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6611                                           size_t allocated_bytes) {
6612   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6613                                GCAllocForSurvived);
6614 }
6615 
6616 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6617                                                   bool force) {
6618   assert(!force, "not supported for GC alloc regions");
6619   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6620 }
6621 
6622 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6623                                      size_t allocated_bytes) {
6624   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6625                                GCAllocForTenured);
6626 }
6627 // Heap region set verification
6628 
6629 class VerifyRegionListsClosure : public HeapRegionClosure {
6630 private:
6631   FreeRegionList*     _free_list;
6632   OldRegionSet*       _old_set;
6633   HumongousRegionSet* _humongous_set;
6634   uint                _region_count;
6635 
6636 public:
6637   VerifyRegionListsClosure(OldRegionSet* old_set,
6638                            HumongousRegionSet* humongous_set,
6639                            FreeRegionList* free_list) :
6640     _old_set(old_set), _humongous_set(humongous_set),
6641     _free_list(free_list), _region_count(0) { }
6642 
6643   uint region_count() { return _region_count; }
6644 
6645   bool doHeapRegion(HeapRegion* hr) {
6646     _region_count += 1;
6647 
6648     if (hr->continuesHumongous()) {
6649       return false;
6650     }
6651 
6652     if (hr->is_young()) {
6653       // TODO
6654     } else if (hr->startsHumongous()) {
6655       _humongous_set->verify_next_region(hr);
6656     } else if (hr->is_empty()) {
6657       _free_list->verify_next_region(hr);
6658     } else {
6659       _old_set->verify_next_region(hr);
6660     }
6661     return false;
6662   }
6663 };
6664 
6665 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6666                                              HeapWord* bottom) {
6667   HeapWord* end = bottom + HeapRegion::GrainWords;
6668   MemRegion mr(bottom, end);
6669   assert(_g1_reserved.contains(mr), "invariant");
6670   // This might return NULL if the allocation fails
6671   return new HeapRegion(hrs_index, _bot_shared, mr);
6672 }
6673 
6674 void G1CollectedHeap::verify_region_sets() {
6675   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6676 
6677   // First, check the explicit lists.
6678   _free_list.verify();
6679   {
6680     // Given that a concurrent operation might be adding regions to
6681     // the secondary free list we have to take the lock before
6682     // verifying it.
6683     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6684     _secondary_free_list.verify();
6685   }
6686   _old_set.verify();
6687   _humongous_set.verify();
6688 
6689   // If a concurrent region freeing operation is in progress it will
6690   // be difficult to correctly attributed any free regions we come
6691   // across to the correct free list given that they might belong to
6692   // one of several (free_list, secondary_free_list, any local lists,
6693   // etc.). So, if that's the case we will skip the rest of the
6694   // verification operation. Alternatively, waiting for the concurrent
6695   // operation to complete will have a non-trivial effect on the GC's
6696   // operation (no concurrent operation will last longer than the
6697   // interval between two calls to verification) and it might hide
6698   // any issues that we would like to catch during testing.
6699   if (free_regions_coming()) {
6700     return;
6701   }
6702 
6703   // Make sure we append the secondary_free_list on the free_list so
6704   // that all free regions we will come across can be safely
6705   // attributed to the free_list.
6706   append_secondary_free_list_if_not_empty_with_lock();
6707 
6708   // Finally, make sure that the region accounting in the lists is
6709   // consistent with what we see in the heap.
6710   _old_set.verify_start();
6711   _humongous_set.verify_start();
6712   _free_list.verify_start();
6713 
6714   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6715   heap_region_iterate(&cl);
6716 
6717   _old_set.verify_end();
6718   _humongous_set.verify_end();
6719   _free_list.verify_end();
6720 }
6721 
6722 // Optimized nmethod scanning
6723 
6724 class RegisterNMethodOopClosure: public OopClosure {
6725   G1CollectedHeap* _g1h;
6726   nmethod* _nm;
6727 
6728   template <class T> void do_oop_work(T* p) {
6729     T heap_oop = oopDesc::load_heap_oop(p);
6730     if (!oopDesc::is_null(heap_oop)) {
6731       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6732       HeapRegion* hr = _g1h->heap_region_containing(obj);
6733       assert(!hr->continuesHumongous(),
6734              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6735                      " starting at "HR_FORMAT,
6736                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6737 
6738       // HeapRegion::add_strong_code_root() avoids adding duplicate
6739       // entries but having duplicates is  OK since we "mark" nmethods
6740       // as visited when we scan the strong code root lists during the GC.
6741       hr->add_strong_code_root(_nm);
6742       assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6743              err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6744                      _nm, HR_FORMAT_PARAMS(hr)));
6745     }
6746   }
6747 
6748 public:
6749   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6750     _g1h(g1h), _nm(nm) {}
6751 
6752   void do_oop(oop* p)       { do_oop_work(p); }
6753   void do_oop(narrowOop* p) { do_oop_work(p); }
6754 };
6755 
6756 class UnregisterNMethodOopClosure: public OopClosure {
6757   G1CollectedHeap* _g1h;
6758   nmethod* _nm;
6759 
6760   template <class T> void do_oop_work(T* p) {
6761     T heap_oop = oopDesc::load_heap_oop(p);
6762     if (!oopDesc::is_null(heap_oop)) {
6763       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6764       HeapRegion* hr = _g1h->heap_region_containing(obj);
6765       assert(!hr->continuesHumongous(),
6766              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6767                      " starting at "HR_FORMAT,
6768                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6769 
6770       hr->remove_strong_code_root(_nm);
6771       assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6772              err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6773                      _nm, HR_FORMAT_PARAMS(hr)));
6774     }
6775   }
6776 
6777 public:
6778   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6779     _g1h(g1h), _nm(nm) {}
6780 
6781   void do_oop(oop* p)       { do_oop_work(p); }
6782   void do_oop(narrowOop* p) { do_oop_work(p); }
6783 };
6784 
6785 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6786   CollectedHeap::register_nmethod(nm);
6787 
6788   guarantee(nm != NULL, "sanity");
6789   RegisterNMethodOopClosure reg_cl(this, nm);
6790   nm->oops_do(&reg_cl);
6791 }
6792 
6793 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6794   CollectedHeap::unregister_nmethod(nm);
6795 
6796   guarantee(nm != NULL, "sanity");
6797   UnregisterNMethodOopClosure reg_cl(this, nm);
6798   nm->oops_do(&reg_cl, true);
6799 }
6800 
6801 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6802 public:
6803   bool doHeapRegion(HeapRegion *hr) {
6804     assert(!hr->isHumongous(),
6805            err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6806                    HR_FORMAT_PARAMS(hr)));
6807     hr->migrate_strong_code_roots();
6808     return false;
6809   }
6810 };
6811 
6812 void G1CollectedHeap::migrate_strong_code_roots() {
6813   MigrateCodeRootsHeapRegionClosure cl;
6814   double migrate_start = os::elapsedTime();
6815   collection_set_iterate(&cl);
6816   double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6817   g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6818 }
6819 
6820 // Mark all the code roots that point into regions *not* in the
6821 // collection set.
6822 //
6823 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6824 // walking the the code roots lists of regions not in the collection
6825 // set. Suppose we have an nmethod (M) that points to objects in two
6826 // separate regions - one in the collection set (R1) and one not (R2).
6827 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6828 // nmethod M when walking the code roots for R1. When we come to scan
6829 // the code roots for R2, we would see that M is already marked and it
6830 // would be skipped and the objects in R2 that are referenced from M
6831 // would not be evacuated.
6832 
6833 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6834 
6835   class MarkStrongCodeRootOopClosure: public OopClosure {
6836     ConcurrentMark* _cm;
6837     HeapRegion* _hr;
6838     uint _worker_id;
6839 
6840     template <class T> void do_oop_work(T* p) {
6841       T heap_oop = oopDesc::load_heap_oop(p);
6842       if (!oopDesc::is_null(heap_oop)) {
6843         oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6844         // Only mark objects in the region (which is assumed
6845         // to be not in the collection set).
6846         if (_hr->is_in(obj)) {
6847           _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6848         }
6849       }
6850     }
6851 
6852   public:
6853     MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6854       _cm(cm), _hr(hr), _worker_id(worker_id) {
6855       assert(!_hr->in_collection_set(), "sanity");
6856     }
6857 
6858     void do_oop(narrowOop* p) { do_oop_work(p); }
6859     void do_oop(oop* p)       { do_oop_work(p); }
6860   };
6861 
6862   MarkStrongCodeRootOopClosure _oop_cl;
6863 
6864 public:
6865   MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6866     _oop_cl(cm, hr, worker_id) {}
6867 
6868   void do_code_blob(CodeBlob* cb) {
6869     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6870     if (nm != NULL) {
6871       nm->oops_do(&_oop_cl);
6872     }
6873   }
6874 };
6875 
6876 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6877   G1CollectedHeap* _g1h;
6878   uint _worker_id;
6879 
6880 public:
6881   MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6882     _g1h(g1h), _worker_id(worker_id) {}
6883 
6884   bool doHeapRegion(HeapRegion *hr) {
6885     HeapRegionRemSet* hrrs = hr->rem_set();
6886     if (hr->continuesHumongous()) {
6887       // Code roots should never be attached to a continuation of a humongous region
6888       assert(hrrs->strong_code_roots_list_length() == 0,
6889              err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6890                      " starting at "HR_FORMAT", but has "INT32_FORMAT,
6891                      HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6892                      hrrs->strong_code_roots_list_length()));
6893       return false;
6894     }
6895 
6896     if (hr->in_collection_set()) {
6897       // Don't mark code roots into regions in the collection set here.
6898       // They will be marked when we scan them.
6899       return false;
6900     }
6901 
6902     MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6903     hr->strong_code_roots_do(&cb_cl);
6904     return false;
6905   }
6906 };
6907 
6908 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6909   MarkStrongCodeRootsHRClosure cl(this, worker_id);
6910   if (G1CollectedHeap::use_parallel_gc_threads()) {
6911     heap_region_par_iterate_chunked(&cl,
6912                                     worker_id,
6913                                     workers()->active_workers(),
6914                                     HeapRegion::ParMarkRootClaimValue);
6915   } else {
6916     heap_region_iterate(&cl);
6917   }
6918 }
6919 
6920 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6921   G1CollectedHeap* _g1h;
6922 
6923 public:
6924   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6925     _g1h(g1h) {}
6926 
6927   void do_code_blob(CodeBlob* cb) {
6928     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6929     if (nm == NULL) {
6930       return;
6931     }
6932 
6933     if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6934       _g1h->register_nmethod(nm);
6935     }
6936   }
6937 };
6938 
6939 void G1CollectedHeap::rebuild_strong_code_roots() {
6940   RebuildStrongCodeRootClosure blob_cl(this);
6941   CodeCache::blobs_do(&blob_cl);
6942 }