1 /*
   2  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "code/codeCache.hpp"
  27 #include "code/icBuffer.hpp"
  28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  36 #include "gc_implementation/g1/g1EvacFailure.hpp"
  37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  38 #include "gc_implementation/g1/g1Log.hpp"
  39 #include "gc_implementation/g1/g1MarkSweep.hpp"
  40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  42 #include "gc_implementation/g1/g1YCTypes.hpp"
  43 #include "gc_implementation/g1/heapRegion.inline.hpp"
  44 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  46 #include "gc_implementation/g1/vm_operations_g1.hpp"
  47 #include "gc_implementation/shared/gcHeapSummary.hpp"
  48 #include "gc_implementation/shared/gcTimer.hpp"
  49 #include "gc_implementation/shared/gcTrace.hpp"
  50 #include "gc_implementation/shared/gcTraceTime.hpp"
  51 #include "gc_implementation/shared/isGCActiveMark.hpp"
  52 #include "memory/gcLocker.inline.hpp"
  53 #include "memory/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   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1579 
1580   // Include the current allocation, if any, and bytes that will be
1581   // pre-allocated to support collections, as "used".
1582   const size_t used_after_gc = used();
1583   const size_t capacity_after_gc = capacity();
1584   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1585 
1586   // This is enforced in arguments.cpp.
1587   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1588          "otherwise the code below doesn't make sense");
1589 
1590   // We don't have floating point command-line arguments
1591   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1592   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1593   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1594   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1595 
1596   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1597   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1598 
1599   // We have to be careful here as these two calculations can overflow
1600   // 32-bit size_t's.
1601   double used_after_gc_d = (double) used_after_gc;
1602   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1603   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1604 
1605   // Let's make sure that they are both under the max heap size, which
1606   // by default will make them fit into a size_t.
1607   double desired_capacity_upper_bound = (double) max_heap_size;
1608   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1609                                     desired_capacity_upper_bound);
1610   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1611                                     desired_capacity_upper_bound);
1612 
1613   // We can now safely turn them into size_t's.
1614   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1615   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1616 
1617   // This assert only makes sense here, before we adjust them
1618   // with respect to the min and max heap size.
1619   assert(minimum_desired_capacity <= maximum_desired_capacity,
1620          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1621                  "maximum_desired_capacity = "SIZE_FORMAT,
1622                  minimum_desired_capacity, maximum_desired_capacity));
1623 
1624   // Should not be greater than the heap max size. No need to adjust
1625   // it with respect to the heap min size as it's a lower bound (i.e.,
1626   // we'll try to make the capacity larger than it, not smaller).
1627   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1628   // Should not be less than the heap min size. No need to adjust it
1629   // with respect to the heap max size as it's an upper bound (i.e.,
1630   // we'll try to make the capacity smaller than it, not greater).
1631   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1632 
1633   if (capacity_after_gc < minimum_desired_capacity) {
1634     // Don't expand unless it's significant
1635     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1636     ergo_verbose4(ErgoHeapSizing,
1637                   "attempt heap expansion",
1638                   ergo_format_reason("capacity lower than "
1639                                      "min desired capacity after Full GC")
1640                   ergo_format_byte("capacity")
1641                   ergo_format_byte("occupancy")
1642                   ergo_format_byte_perc("min desired capacity"),
1643                   capacity_after_gc, used_after_gc,
1644                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1645     expand(expand_bytes);
1646 
1647     // No expansion, now see if we want to shrink
1648   } else if (capacity_after_gc > maximum_desired_capacity) {
1649     // Capacity too large, compute shrinking size
1650     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1651     ergo_verbose4(ErgoHeapSizing,
1652                   "attempt heap shrinking",
1653                   ergo_format_reason("capacity higher than "
1654                                      "max desired capacity after Full GC")
1655                   ergo_format_byte("capacity")
1656                   ergo_format_byte("occupancy")
1657                   ergo_format_byte_perc("max desired capacity"),
1658                   capacity_after_gc, used_after_gc,
1659                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1660     shrink(shrink_bytes);
1661   }
1662 }
1663 
1664 
1665 HeapWord*
1666 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1667                                            bool* succeeded) {
1668   assert_at_safepoint(true /* should_be_vm_thread */);
1669 
1670   *succeeded = true;
1671   // Let's attempt the allocation first.
1672   HeapWord* result =
1673     attempt_allocation_at_safepoint(word_size,
1674                                  false /* expect_null_mutator_alloc_region */);
1675   if (result != NULL) {
1676     assert(*succeeded, "sanity");
1677     return result;
1678   }
1679 
1680   // In a G1 heap, we're supposed to keep allocation from failing by
1681   // incremental pauses.  Therefore, at least for now, we'll favor
1682   // expansion over collection.  (This might change in the future if we can
1683   // do something smarter than full collection to satisfy a failed alloc.)
1684   result = expand_and_allocate(word_size);
1685   if (result != NULL) {
1686     assert(*succeeded, "sanity");
1687     return result;
1688   }
1689 
1690   // Expansion didn't work, we'll try to do a Full GC.
1691   bool gc_succeeded = do_collection(false, /* explicit_gc */
1692                                     false, /* clear_all_soft_refs */
1693                                     word_size);
1694   if (!gc_succeeded) {
1695     *succeeded = false;
1696     return NULL;
1697   }
1698 
1699   // Retry the allocation
1700   result = attempt_allocation_at_safepoint(word_size,
1701                                   true /* expect_null_mutator_alloc_region */);
1702   if (result != NULL) {
1703     assert(*succeeded, "sanity");
1704     return result;
1705   }
1706 
1707   // Then, try a Full GC that will collect all soft references.
1708   gc_succeeded = do_collection(false, /* explicit_gc */
1709                                true,  /* clear_all_soft_refs */
1710                                word_size);
1711   if (!gc_succeeded) {
1712     *succeeded = false;
1713     return NULL;
1714   }
1715 
1716   // Retry the allocation once more
1717   result = attempt_allocation_at_safepoint(word_size,
1718                                   true /* expect_null_mutator_alloc_region */);
1719   if (result != NULL) {
1720     assert(*succeeded, "sanity");
1721     return result;
1722   }
1723 
1724   assert(!collector_policy()->should_clear_all_soft_refs(),
1725          "Flag should have been handled and cleared prior to this point");
1726 
1727   // What else?  We might try synchronous finalization later.  If the total
1728   // space available is large enough for the allocation, then a more
1729   // complete compaction phase than we've tried so far might be
1730   // appropriate.
1731   assert(*succeeded, "sanity");
1732   return NULL;
1733 }
1734 
1735 // Attempting to expand the heap sufficiently
1736 // to support an allocation of the given "word_size".  If
1737 // successful, perform the allocation and return the address of the
1738 // allocated block, or else "NULL".
1739 
1740 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1741   assert_at_safepoint(true /* should_be_vm_thread */);
1742 
1743   verify_region_sets_optional();
1744 
1745   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1746   ergo_verbose1(ErgoHeapSizing,
1747                 "attempt heap expansion",
1748                 ergo_format_reason("allocation request failed")
1749                 ergo_format_byte("allocation request"),
1750                 word_size * HeapWordSize);
1751   if (expand(expand_bytes)) {
1752     _hrs.verify_optional();
1753     verify_region_sets_optional();
1754     return attempt_allocation_at_safepoint(word_size,
1755                                  false /* expect_null_mutator_alloc_region */);
1756   }
1757   return NULL;
1758 }
1759 
1760 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1761                                              HeapWord* new_end) {
1762   assert(old_end != new_end, "don't call this otherwise");
1763   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1764 
1765   // Update the committed mem region.
1766   _g1_committed.set_end(new_end);
1767   // Tell the card table about the update.
1768   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1769   // Tell the BOT about the update.
1770   _bot_shared->resize(_g1_committed.word_size());
1771   // Tell the hot card cache about the update
1772   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1773 }
1774 
1775 bool G1CollectedHeap::expand(size_t expand_bytes) {
1776   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1777   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1778                                        HeapRegion::GrainBytes);
1779   ergo_verbose2(ErgoHeapSizing,
1780                 "expand the heap",
1781                 ergo_format_byte("requested expansion amount")
1782                 ergo_format_byte("attempted expansion amount"),
1783                 expand_bytes, aligned_expand_bytes);
1784 
1785   if (_g1_storage.uncommitted_size() == 0) {
1786     ergo_verbose0(ErgoHeapSizing,
1787                       "did not expand the heap",
1788                       ergo_format_reason("heap already fully expanded"));
1789     return false;
1790   }
1791 
1792   // First commit the memory.
1793   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1794   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1795   if (successful) {
1796     // Then propagate this update to the necessary data structures.
1797     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1798     update_committed_space(old_end, new_end);
1799 
1800     FreeRegionList expansion_list("Local Expansion List");
1801     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1802     assert(mr.start() == old_end, "post-condition");
1803     // mr might be a smaller region than what was requested if
1804     // expand_by() was unable to allocate the HeapRegion instances
1805     assert(mr.end() <= new_end, "post-condition");
1806 
1807     size_t actual_expand_bytes = mr.byte_size();
1808     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1809     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1810            "post-condition");
1811     if (actual_expand_bytes < aligned_expand_bytes) {
1812       // We could not expand _hrs to the desired size. In this case we
1813       // need to shrink the committed space accordingly.
1814       assert(mr.end() < new_end, "invariant");
1815 
1816       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1817       // First uncommit the memory.
1818       _g1_storage.shrink_by(diff_bytes);
1819       // Then propagate this update to the necessary data structures.
1820       update_committed_space(new_end, mr.end());
1821     }
1822     _free_list.add_as_tail(&expansion_list);
1823 
1824     if (_hr_printer.is_active()) {
1825       HeapWord* curr = mr.start();
1826       while (curr < mr.end()) {
1827         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1828         _hr_printer.commit(curr, curr_end);
1829         curr = curr_end;
1830       }
1831       assert(curr == mr.end(), "post-condition");
1832     }
1833     g1_policy()->record_new_heap_size(n_regions());
1834   } else {
1835     ergo_verbose0(ErgoHeapSizing,
1836                   "did not expand the heap",
1837                   ergo_format_reason("heap expansion operation failed"));
1838     // The expansion of the virtual storage space was unsuccessful.
1839     // Let's see if it was because we ran out of swap.
1840     if (G1ExitOnExpansionFailure &&
1841         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1842       // We had head room...
1843       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1844     }
1845   }
1846   return successful;
1847 }
1848 
1849 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1850   size_t aligned_shrink_bytes =
1851     ReservedSpace::page_align_size_down(shrink_bytes);
1852   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1853                                          HeapRegion::GrainBytes);
1854   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1855 
1856   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1857   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1858   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1859 
1860   ergo_verbose3(ErgoHeapSizing,
1861                 "shrink the heap",
1862                 ergo_format_byte("requested shrinking amount")
1863                 ergo_format_byte("aligned shrinking amount")
1864                 ergo_format_byte("attempted shrinking amount"),
1865                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1866   if (num_regions_removed > 0) {
1867     _g1_storage.shrink_by(shrunk_bytes);
1868     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1869 
1870     if (_hr_printer.is_active()) {
1871       HeapWord* curr = old_end;
1872       while (curr > new_end) {
1873         HeapWord* curr_end = curr;
1874         curr -= HeapRegion::GrainWords;
1875         _hr_printer.uncommit(curr, curr_end);
1876       }
1877     }
1878 
1879     _expansion_regions += num_regions_removed;
1880     update_committed_space(old_end, new_end);
1881     HeapRegionRemSet::shrink_heap(n_regions());
1882     g1_policy()->record_new_heap_size(n_regions());
1883   } else {
1884     ergo_verbose0(ErgoHeapSizing,
1885                   "did not shrink the heap",
1886                   ergo_format_reason("heap shrinking operation failed"));
1887   }
1888 }
1889 
1890 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1891   verify_region_sets_optional();
1892 
1893   // We should only reach here at the end of a Full GC which means we
1894   // should not not be holding to any GC alloc regions. The method
1895   // below will make sure of that and do any remaining clean up.
1896   abandon_gc_alloc_regions();
1897 
1898   // Instead of tearing down / rebuilding the free lists here, we
1899   // could instead use the remove_all_pending() method on free_list to
1900   // remove only the ones that we need to remove.
1901   tear_down_region_sets(true /* free_list_only */);
1902   shrink_helper(shrink_bytes);
1903   rebuild_region_sets(true /* free_list_only */);
1904 
1905   _hrs.verify_optional();
1906   verify_region_sets_optional();
1907 }
1908 
1909 // Public methods.
1910 
1911 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1912 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1913 #endif // _MSC_VER
1914 
1915 
1916 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1917   SharedHeap(policy_),
1918   _g1_policy(policy_),
1919   _dirty_card_queue_set(false),
1920   _into_cset_dirty_card_queue_set(false),
1921   _is_alive_closure_cm(this),
1922   _is_alive_closure_stw(this),
1923   _ref_processor_cm(NULL),
1924   _ref_processor_stw(NULL),
1925   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1926   _bot_shared(NULL),
1927   _evac_failure_scan_stack(NULL),
1928   _mark_in_progress(false),
1929   _cg1r(NULL), _summary_bytes_used(0),
1930   _g1mm(NULL),
1931   _refine_cte_cl(NULL),
1932   _full_collection(false),
1933   _free_list("Master Free List"),
1934   _secondary_free_list("Secondary Free List"),
1935   _old_set("Old Set"),
1936   _humongous_set("Master Humongous Set"),
1937   _free_regions_coming(false),
1938   _young_list(new YoungList(this)),
1939   _gc_time_stamp(0),
1940   _retained_old_gc_alloc_region(NULL),
1941   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1942   _old_plab_stats(OldPLABSize, PLABWeight),
1943   _expand_heap_after_alloc_failure(true),
1944   _surviving_young_words(NULL),
1945   _old_marking_cycles_started(0),
1946   _old_marking_cycles_completed(0),
1947   _concurrent_cycle_started(false),
1948   _in_cset_fast_test(NULL),
1949   _in_cset_fast_test_base(NULL),
1950   _dirty_cards_region_list(NULL),
1951   _worker_cset_start_region(NULL),
1952   _worker_cset_start_region_time_stamp(NULL),
1953   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1954   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1955   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1956   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1957 
1958   _g1h = this;
1959   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1960     vm_exit_during_initialization("Failed necessary allocation.");
1961   }
1962 
1963   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1964 
1965   int n_queues = MAX2((int)ParallelGCThreads, 1);
1966   _task_queues = new RefToScanQueueSet(n_queues);
1967 
1968   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1969   assert(n_rem_sets > 0, "Invariant.");
1970 
1971   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1972   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1973   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1974 
1975   for (int i = 0; i < n_queues; i++) {
1976     RefToScanQueue* q = new RefToScanQueue();
1977     q->initialize();
1978     _task_queues->register_queue(i, q);
1979     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1980   }
1981   clear_cset_start_regions();
1982 
1983   // Initialize the G1EvacuationFailureALot counters and flags.
1984   NOT_PRODUCT(reset_evacuation_should_fail();)
1985 
1986   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1987 }
1988 
1989 jint G1CollectedHeap::initialize() {
1990   CollectedHeap::pre_initialize();
1991   os::enable_vtime();
1992 
1993   G1Log::init();
1994 
1995   // Necessary to satisfy locking discipline assertions.
1996 
1997   MutexLocker x(Heap_lock);
1998 
1999   // We have to initialize the printer before committing the heap, as
2000   // it will be used then.
2001   _hr_printer.set_active(G1PrintHeapRegions);
2002 
2003   // While there are no constraints in the GC code that HeapWordSize
2004   // be any particular value, there are multiple other areas in the
2005   // system which believe this to be true (e.g. oop->object_size in some
2006   // cases incorrectly returns the size in wordSize units rather than
2007   // HeapWordSize).
2008   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2009 
2010   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2011   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2012   size_t heap_alignment = collector_policy()->heap_alignment();
2013 
2014   // Ensure that the sizes are properly aligned.
2015   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2016   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2017   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2018 
2019   _cg1r = new ConcurrentG1Refine(this);
2020 
2021   // Reserve the maximum.
2022 
2023   // When compressed oops are enabled, the preferred heap base
2024   // is calculated by subtracting the requested size from the
2025   // 32Gb boundary and using the result as the base address for
2026   // heap reservation. If the requested size is not aligned to
2027   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2028   // into the ReservedHeapSpace constructor) then the actual
2029   // base of the reserved heap may end up differing from the
2030   // address that was requested (i.e. the preferred heap base).
2031   // If this happens then we could end up using a non-optimal
2032   // compressed oops mode.
2033 
2034   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2035                                                  heap_alignment);
2036 
2037   // It is important to do this in a way such that concurrent readers can't
2038   // temporarily think something is in the heap.  (I've actually seen this
2039   // happen in asserts: DLD.)
2040   _reserved.set_word_size(0);
2041   _reserved.set_start((HeapWord*)heap_rs.base());
2042   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2043 
2044   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2045 
2046   // Create the gen rem set (and barrier set) for the entire reserved region.
2047   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2048   set_barrier_set(rem_set()->bs());
2049   if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2050     vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2051     return JNI_ENOMEM;
2052   }
2053 
2054   // Also create a G1 rem set.
2055   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2056 
2057   // Carve out the G1 part of the heap.
2058 
2059   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2060   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2061                            g1_rs.size()/HeapWordSize);
2062 
2063   _g1_storage.initialize(g1_rs, 0);
2064   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2065   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2066                   (HeapWord*) _g1_reserved.end());
2067   assert(_hrs.max_length() == _expansion_regions,
2068          err_msg("max length: %u expansion regions: %u",
2069                  _hrs.max_length(), _expansion_regions));
2070 
2071   // Do later initialization work for concurrent refinement.
2072   _cg1r->init();
2073 
2074   // 6843694 - ensure that the maximum region index can fit
2075   // in the remembered set structures.
2076   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2077   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2078 
2079   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2080   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2081   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2082             "too many cards per region");
2083 
2084   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2085 
2086   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2087                                              heap_word_size(init_byte_size));
2088 
2089   _g1h = this;
2090 
2091   _in_cset_fast_test_length = max_regions();
2092   _in_cset_fast_test_base =
2093                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2094 
2095   // We're biasing _in_cset_fast_test to avoid subtracting the
2096   // beginning of the heap every time we want to index; basically
2097   // it's the same with what we do with the card table.
2098   _in_cset_fast_test = _in_cset_fast_test_base -
2099                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2100 
2101   // Clear the _cset_fast_test bitmap in anticipation of adding
2102   // regions to the incremental collection set for the first
2103   // evacuation pause.
2104   clear_cset_fast_test();
2105 
2106   // Create the ConcurrentMark data structure and thread.
2107   // (Must do this late, so that "max_regions" is defined.)
2108   _cm = new ConcurrentMark(this, heap_rs);
2109   if (_cm == NULL || !_cm->completed_initialization()) {
2110     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2111     return JNI_ENOMEM;
2112   }
2113   _cmThread = _cm->cmThread();
2114 
2115   // Initialize the from_card cache structure of HeapRegionRemSet.
2116   HeapRegionRemSet::init_heap(max_regions());
2117 
2118   // Now expand into the initial heap size.
2119   if (!expand(init_byte_size)) {
2120     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2121     return JNI_ENOMEM;
2122   }
2123 
2124   // Perform any initialization actions delegated to the policy.
2125   g1_policy()->init();
2126 
2127   _refine_cte_cl =
2128     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2129                                     g1_rem_set(),
2130                                     concurrent_g1_refine());
2131   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2132 
2133   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2134                                                SATB_Q_FL_lock,
2135                                                G1SATBProcessCompletedThreshold,
2136                                                Shared_SATB_Q_lock);
2137 
2138   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2139                                                 DirtyCardQ_FL_lock,
2140                                                 concurrent_g1_refine()->yellow_zone(),
2141                                                 concurrent_g1_refine()->red_zone(),
2142                                                 Shared_DirtyCardQ_lock);
2143 
2144   if (G1DeferredRSUpdate) {
2145     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2146                                       DirtyCardQ_FL_lock,
2147                                       -1, // never trigger processing
2148                                       -1, // no limit on length
2149                                       Shared_DirtyCardQ_lock,
2150                                       &JavaThread::dirty_card_queue_set());
2151   }
2152 
2153   // Initialize the card queue set used to hold cards containing
2154   // references into the collection set.
2155   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2156                                              DirtyCardQ_FL_lock,
2157                                              -1, // never trigger processing
2158                                              -1, // no limit on length
2159                                              Shared_DirtyCardQ_lock,
2160                                              &JavaThread::dirty_card_queue_set());
2161 
2162   // In case we're keeping closure specialization stats, initialize those
2163   // counts and that mechanism.
2164   SpecializationStats::clear();
2165 
2166   // Here we allocate the dummy full region that is required by the
2167   // G1AllocRegion class. If we don't pass an address in the reserved
2168   // space here, lots of asserts fire.
2169 
2170   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2171                                              _g1_reserved.start());
2172   // We'll re-use the same region whether the alloc region will
2173   // require BOT updates or not and, if it doesn't, then a non-young
2174   // region will complain that it cannot support allocations without
2175   // BOT updates. So we'll tag the dummy region as young to avoid that.
2176   dummy_region->set_young();
2177   // Make sure it's full.
2178   dummy_region->set_top(dummy_region->end());
2179   G1AllocRegion::setup(this, dummy_region);
2180 
2181   init_mutator_alloc_region();
2182 
2183   // Do create of the monitoring and management support so that
2184   // values in the heap have been properly initialized.
2185   _g1mm = new G1MonitoringSupport(this);
2186 
2187   return JNI_OK;
2188 }
2189 
2190 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2191   return HeapRegion::max_region_size();
2192 }
2193 
2194 void G1CollectedHeap::ref_processing_init() {
2195   // Reference processing in G1 currently works as follows:
2196   //
2197   // * There are two reference processor instances. One is
2198   //   used to record and process discovered references
2199   //   during concurrent marking; the other is used to
2200   //   record and process references during STW pauses
2201   //   (both full and incremental).
2202   // * Both ref processors need to 'span' the entire heap as
2203   //   the regions in the collection set may be dotted around.
2204   //
2205   // * For the concurrent marking ref processor:
2206   //   * Reference discovery is enabled at initial marking.
2207   //   * Reference discovery is disabled and the discovered
2208   //     references processed etc during remarking.
2209   //   * Reference discovery is MT (see below).
2210   //   * Reference discovery requires a barrier (see below).
2211   //   * Reference processing may or may not be MT
2212   //     (depending on the value of ParallelRefProcEnabled
2213   //     and ParallelGCThreads).
2214   //   * A full GC disables reference discovery by the CM
2215   //     ref processor and abandons any entries on it's
2216   //     discovered lists.
2217   //
2218   // * For the STW processor:
2219   //   * Non MT discovery is enabled at the start of a full GC.
2220   //   * Processing and enqueueing during a full GC is non-MT.
2221   //   * During a full GC, references are processed after marking.
2222   //
2223   //   * Discovery (may or may not be MT) is enabled at the start
2224   //     of an incremental evacuation pause.
2225   //   * References are processed near the end of a STW evacuation pause.
2226   //   * For both types of GC:
2227   //     * Discovery is atomic - i.e. not concurrent.
2228   //     * Reference discovery will not need a barrier.
2229 
2230   SharedHeap::ref_processing_init();
2231   MemRegion mr = reserved_region();
2232 
2233   // Concurrent Mark ref processor
2234   _ref_processor_cm =
2235     new ReferenceProcessor(mr,    // span
2236                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2237                                 // mt processing
2238                            (int) ParallelGCThreads,
2239                                 // degree of mt processing
2240                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2241                                 // mt discovery
2242                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2243                                 // degree of mt discovery
2244                            false,
2245                                 // Reference discovery is not atomic
2246                            &_is_alive_closure_cm,
2247                                 // is alive closure
2248                                 // (for efficiency/performance)
2249                            true);
2250                                 // Setting next fields of discovered
2251                                 // lists requires a barrier.
2252 
2253   // STW ref processor
2254   _ref_processor_stw =
2255     new ReferenceProcessor(mr,    // span
2256                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2257                                 // mt processing
2258                            MAX2((int)ParallelGCThreads, 1),
2259                                 // degree of mt processing
2260                            (ParallelGCThreads > 1),
2261                                 // mt discovery
2262                            MAX2((int)ParallelGCThreads, 1),
2263                                 // degree of mt discovery
2264                            true,
2265                                 // Reference discovery is atomic
2266                            &_is_alive_closure_stw,
2267                                 // is alive closure
2268                                 // (for efficiency/performance)
2269                            false);
2270                                 // Setting next fields of discovered
2271                                 // lists requires a barrier.
2272 }
2273 
2274 size_t G1CollectedHeap::capacity() const {
2275   return _g1_committed.byte_size();
2276 }
2277 
2278 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2279   assert(!hr->continuesHumongous(), "pre-condition");
2280   hr->reset_gc_time_stamp();
2281   if (hr->startsHumongous()) {
2282     uint first_index = hr->hrs_index() + 1;
2283     uint last_index = hr->last_hc_index();
2284     for (uint i = first_index; i < last_index; i += 1) {
2285       HeapRegion* chr = region_at(i);
2286       assert(chr->continuesHumongous(), "sanity");
2287       chr->reset_gc_time_stamp();
2288     }
2289   }
2290 }
2291 
2292 #ifndef PRODUCT
2293 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2294 private:
2295   unsigned _gc_time_stamp;
2296   bool _failures;
2297 
2298 public:
2299   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2300     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2301 
2302   virtual bool doHeapRegion(HeapRegion* hr) {
2303     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2304     if (_gc_time_stamp != region_gc_time_stamp) {
2305       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2306                              "expected %d", HR_FORMAT_PARAMS(hr),
2307                              region_gc_time_stamp, _gc_time_stamp);
2308       _failures = true;
2309     }
2310     return false;
2311   }
2312 
2313   bool failures() { return _failures; }
2314 };
2315 
2316 void G1CollectedHeap::check_gc_time_stamps() {
2317   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2318   heap_region_iterate(&cl);
2319   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2320 }
2321 #endif // PRODUCT
2322 
2323 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2324                                                  DirtyCardQueue* into_cset_dcq,
2325                                                  bool concurrent,
2326                                                  int worker_i) {
2327   // Clean cards in the hot card cache
2328   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2329   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2330 
2331   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2332   int n_completed_buffers = 0;
2333   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2334     n_completed_buffers++;
2335   }
2336   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2337   dcqs.clear_n_completed_buffers();
2338   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2339 }
2340 
2341 
2342 // Computes the sum of the storage used by the various regions.
2343 
2344 size_t G1CollectedHeap::used() const {
2345   assert(Heap_lock->owner() != NULL,
2346          "Should be owned on this thread's behalf.");
2347   size_t result = _summary_bytes_used;
2348   // Read only once in case it is set to NULL concurrently
2349   HeapRegion* hr = _mutator_alloc_region.get();
2350   if (hr != NULL)
2351     result += hr->used();
2352   return result;
2353 }
2354 
2355 size_t G1CollectedHeap::used_unlocked() const {
2356   size_t result = _summary_bytes_used;
2357   return result;
2358 }
2359 
2360 class SumUsedClosure: public HeapRegionClosure {
2361   size_t _used;
2362 public:
2363   SumUsedClosure() : _used(0) {}
2364   bool doHeapRegion(HeapRegion* r) {
2365     if (!r->continuesHumongous()) {
2366       _used += r->used();
2367     }
2368     return false;
2369   }
2370   size_t result() { return _used; }
2371 };
2372 
2373 size_t G1CollectedHeap::recalculate_used() const {
2374   SumUsedClosure blk;
2375   heap_region_iterate(&blk);
2376   return blk.result();
2377 }
2378 
2379 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2380   switch (cause) {
2381     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2382     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2383     case GCCause::_g1_humongous_allocation: return true;
2384     default:                                return false;
2385   }
2386 }
2387 
2388 #ifndef PRODUCT
2389 void G1CollectedHeap::allocate_dummy_regions() {
2390   // Let's fill up most of the region
2391   size_t word_size = HeapRegion::GrainWords - 1024;
2392   // And as a result the region we'll allocate will be humongous.
2393   guarantee(isHumongous(word_size), "sanity");
2394 
2395   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2396     // Let's use the existing mechanism for the allocation
2397     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2398     if (dummy_obj != NULL) {
2399       MemRegion mr(dummy_obj, word_size);
2400       CollectedHeap::fill_with_object(mr);
2401     } else {
2402       // If we can't allocate once, we probably cannot allocate
2403       // again. Let's get out of the loop.
2404       break;
2405     }
2406   }
2407 }
2408 #endif // !PRODUCT
2409 
2410 void G1CollectedHeap::increment_old_marking_cycles_started() {
2411   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2412     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2413     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2414     _old_marking_cycles_started, _old_marking_cycles_completed));
2415 
2416   _old_marking_cycles_started++;
2417 }
2418 
2419 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2420   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2421 
2422   // We assume that if concurrent == true, then the caller is a
2423   // concurrent thread that was joined the Suspendible Thread
2424   // Set. If there's ever a cheap way to check this, we should add an
2425   // assert here.
2426 
2427   // Given that this method is called at the end of a Full GC or of a
2428   // concurrent cycle, and those can be nested (i.e., a Full GC can
2429   // interrupt a concurrent cycle), the number of full collections
2430   // completed should be either one (in the case where there was no
2431   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2432   // behind the number of full collections started.
2433 
2434   // This is the case for the inner caller, i.e. a Full GC.
2435   assert(concurrent ||
2436          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2437          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2438          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2439                  "is inconsistent with _old_marking_cycles_completed = %u",
2440                  _old_marking_cycles_started, _old_marking_cycles_completed));
2441 
2442   // This is the case for the outer caller, i.e. the concurrent cycle.
2443   assert(!concurrent ||
2444          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2445          err_msg("for outer caller (concurrent cycle): "
2446                  "_old_marking_cycles_started = %u "
2447                  "is inconsistent with _old_marking_cycles_completed = %u",
2448                  _old_marking_cycles_started, _old_marking_cycles_completed));
2449 
2450   _old_marking_cycles_completed += 1;
2451 
2452   // We need to clear the "in_progress" flag in the CM thread before
2453   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2454   // is set) so that if a waiter requests another System.gc() it doesn't
2455   // incorrectly see that a marking cycle is still in progress.
2456   if (concurrent) {
2457     _cmThread->clear_in_progress();
2458   }
2459 
2460   // This notify_all() will ensure that a thread that called
2461   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2462   // and it's waiting for a full GC to finish will be woken up. It is
2463   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2464   FullGCCount_lock->notify_all();
2465 }
2466 
2467 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2468   _concurrent_cycle_started = true;
2469   _gc_timer_cm->register_gc_start(start_time);
2470 
2471   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2472   trace_heap_before_gc(_gc_tracer_cm);
2473 }
2474 
2475 void G1CollectedHeap::register_concurrent_cycle_end() {
2476   if (_concurrent_cycle_started) {
2477     if (_cm->has_aborted()) {
2478       _gc_tracer_cm->report_concurrent_mode_failure();
2479     }
2480 
2481     _gc_timer_cm->register_gc_end();
2482     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2483 
2484     _concurrent_cycle_started = false;
2485   }
2486 }
2487 
2488 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2489   if (_concurrent_cycle_started) {
2490     trace_heap_after_gc(_gc_tracer_cm);
2491   }
2492 }
2493 
2494 G1YCType G1CollectedHeap::yc_type() {
2495   bool is_young = g1_policy()->gcs_are_young();
2496   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2497   bool is_during_mark = mark_in_progress();
2498 
2499   if (is_initial_mark) {
2500     return InitialMark;
2501   } else if (is_during_mark) {
2502     return DuringMark;
2503   } else if (is_young) {
2504     return Normal;
2505   } else {
2506     return Mixed;
2507   }
2508 }
2509 
2510 void G1CollectedHeap::collect(GCCause::Cause cause) {
2511   assert_heap_not_locked();
2512 
2513   unsigned int gc_count_before;
2514   unsigned int old_marking_count_before;
2515   bool retry_gc;
2516 
2517   do {
2518     retry_gc = false;
2519 
2520     {
2521       MutexLocker ml(Heap_lock);
2522 
2523       // Read the GC count while holding the Heap_lock
2524       gc_count_before = total_collections();
2525       old_marking_count_before = _old_marking_cycles_started;
2526     }
2527 
2528     if (should_do_concurrent_full_gc(cause)) {
2529       // Schedule an initial-mark evacuation pause that will start a
2530       // concurrent cycle. We're setting word_size to 0 which means that
2531       // we are not requesting a post-GC allocation.
2532       VM_G1IncCollectionPause op(gc_count_before,
2533                                  0,     /* word_size */
2534                                  true,  /* should_initiate_conc_mark */
2535                                  g1_policy()->max_pause_time_ms(),
2536                                  cause);
2537 
2538       VMThread::execute(&op);
2539       if (!op.pause_succeeded()) {
2540         if (old_marking_count_before == _old_marking_cycles_started) {
2541           retry_gc = op.should_retry_gc();
2542         } else {
2543           // A Full GC happened while we were trying to schedule the
2544           // initial-mark GC. No point in starting a new cycle given
2545           // that the whole heap was collected anyway.
2546         }
2547 
2548         if (retry_gc) {
2549           if (GC_locker::is_active_and_needs_gc()) {
2550             GC_locker::stall_until_clear();
2551           }
2552         }
2553       }
2554     } else {
2555       if (cause == GCCause::_gc_locker
2556           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2557 
2558         // Schedule a standard evacuation pause. We're setting word_size
2559         // to 0 which means that we are not requesting a post-GC allocation.
2560         VM_G1IncCollectionPause op(gc_count_before,
2561                                    0,     /* word_size */
2562                                    false, /* should_initiate_conc_mark */
2563                                    g1_policy()->max_pause_time_ms(),
2564                                    cause);
2565         VMThread::execute(&op);
2566       } else {
2567         // Schedule a Full GC.
2568         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2569         VMThread::execute(&op);
2570       }
2571     }
2572   } while (retry_gc);
2573 }
2574 
2575 bool G1CollectedHeap::is_in(const void* p) const {
2576   if (_g1_committed.contains(p)) {
2577     // Given that we know that p is in the committed space,
2578     // heap_region_containing_raw() should successfully
2579     // return the containing region.
2580     HeapRegion* hr = heap_region_containing_raw(p);
2581     return hr->is_in(p);
2582   } else {
2583     return false;
2584   }
2585 }
2586 
2587 // Iteration functions.
2588 
2589 // Iterates an OopClosure over all ref-containing fields of objects
2590 // within a HeapRegion.
2591 
2592 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2593   MemRegion _mr;
2594   ExtendedOopClosure* _cl;
2595 public:
2596   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2597     : _mr(mr), _cl(cl) {}
2598   bool doHeapRegion(HeapRegion* r) {
2599     if (!r->continuesHumongous()) {
2600       r->oop_iterate(_cl);
2601     }
2602     return false;
2603   }
2604 };
2605 
2606 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2607   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2608   heap_region_iterate(&blk);
2609 }
2610 
2611 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2612   IterateOopClosureRegionClosure blk(mr, cl);
2613   heap_region_iterate(&blk);
2614 }
2615 
2616 // Iterates an ObjectClosure over all objects within a HeapRegion.
2617 
2618 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2619   ObjectClosure* _cl;
2620 public:
2621   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2622   bool doHeapRegion(HeapRegion* r) {
2623     if (! r->continuesHumongous()) {
2624       r->object_iterate(_cl);
2625     }
2626     return false;
2627   }
2628 };
2629 
2630 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2631   IterateObjectClosureRegionClosure blk(cl);
2632   heap_region_iterate(&blk);
2633 }
2634 
2635 // Calls a SpaceClosure on a HeapRegion.
2636 
2637 class SpaceClosureRegionClosure: public HeapRegionClosure {
2638   SpaceClosure* _cl;
2639 public:
2640   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2641   bool doHeapRegion(HeapRegion* r) {
2642     _cl->do_space(r);
2643     return false;
2644   }
2645 };
2646 
2647 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2648   SpaceClosureRegionClosure blk(cl);
2649   heap_region_iterate(&blk);
2650 }
2651 
2652 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2653   _hrs.iterate(cl);
2654 }
2655 
2656 void
2657 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2658                                                  uint worker_id,
2659                                                  uint no_of_par_workers,
2660                                                  jint claim_value) {
2661   const uint regions = n_regions();
2662   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2663                              no_of_par_workers :
2664                              1);
2665   assert(UseDynamicNumberOfGCThreads ||
2666          no_of_par_workers == workers()->total_workers(),
2667          "Non dynamic should use fixed number of workers");
2668   // try to spread out the starting points of the workers
2669   const HeapRegion* start_hr =
2670                         start_region_for_worker(worker_id, no_of_par_workers);
2671   const uint start_index = start_hr->hrs_index();
2672 
2673   // each worker will actually look at all regions
2674   for (uint count = 0; count < regions; ++count) {
2675     const uint index = (start_index + count) % regions;
2676     assert(0 <= index && index < regions, "sanity");
2677     HeapRegion* r = region_at(index);
2678     // we'll ignore "continues humongous" regions (we'll process them
2679     // when we come across their corresponding "start humongous"
2680     // region) and regions already claimed
2681     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2682       continue;
2683     }
2684     // OK, try to claim it
2685     if (r->claimHeapRegion(claim_value)) {
2686       // success!
2687       assert(!r->continuesHumongous(), "sanity");
2688       if (r->startsHumongous()) {
2689         // If the region is "starts humongous" we'll iterate over its
2690         // "continues humongous" first; in fact we'll do them
2691         // first. The order is important. In on case, calling the
2692         // closure on the "starts humongous" region might de-allocate
2693         // and clear all its "continues humongous" regions and, as a
2694         // result, we might end up processing them twice. So, we'll do
2695         // them first (notice: most closures will ignore them anyway) and
2696         // then we'll do the "starts humongous" region.
2697         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2698           HeapRegion* chr = region_at(ch_index);
2699 
2700           // if the region has already been claimed or it's not
2701           // "continues humongous" we're done
2702           if (chr->claim_value() == claim_value ||
2703               !chr->continuesHumongous()) {
2704             break;
2705           }
2706 
2707           // No one should have claimed it directly. We can given
2708           // that we claimed its "starts humongous" region.
2709           assert(chr->claim_value() != claim_value, "sanity");
2710           assert(chr->humongous_start_region() == r, "sanity");
2711 
2712           if (chr->claimHeapRegion(claim_value)) {
2713             // we should always be able to claim it; no one else should
2714             // be trying to claim this region
2715 
2716             bool res2 = cl->doHeapRegion(chr);
2717             assert(!res2, "Should not abort");
2718 
2719             // Right now, this holds (i.e., no closure that actually
2720             // does something with "continues humongous" regions
2721             // clears them). We might have to weaken it in the future,
2722             // but let's leave these two asserts here for extra safety.
2723             assert(chr->continuesHumongous(), "should still be the case");
2724             assert(chr->humongous_start_region() == r, "sanity");
2725           } else {
2726             guarantee(false, "we should not reach here");
2727           }
2728         }
2729       }
2730 
2731       assert(!r->continuesHumongous(), "sanity");
2732       bool res = cl->doHeapRegion(r);
2733       assert(!res, "Should not abort");
2734     }
2735   }
2736 }
2737 
2738 class ResetClaimValuesClosure: public HeapRegionClosure {
2739 public:
2740   bool doHeapRegion(HeapRegion* r) {
2741     r->set_claim_value(HeapRegion::InitialClaimValue);
2742     return false;
2743   }
2744 };
2745 
2746 void G1CollectedHeap::reset_heap_region_claim_values() {
2747   ResetClaimValuesClosure blk;
2748   heap_region_iterate(&blk);
2749 }
2750 
2751 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2752   ResetClaimValuesClosure blk;
2753   collection_set_iterate(&blk);
2754 }
2755 
2756 #ifdef ASSERT
2757 // This checks whether all regions in the heap have the correct claim
2758 // value. I also piggy-backed on this a check to ensure that the
2759 // humongous_start_region() information on "continues humongous"
2760 // regions is correct.
2761 
2762 class CheckClaimValuesClosure : public HeapRegionClosure {
2763 private:
2764   jint _claim_value;
2765   uint _failures;
2766   HeapRegion* _sh_region;
2767 
2768 public:
2769   CheckClaimValuesClosure(jint claim_value) :
2770     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2771   bool doHeapRegion(HeapRegion* r) {
2772     if (r->claim_value() != _claim_value) {
2773       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2774                              "claim value = %d, should be %d",
2775                              HR_FORMAT_PARAMS(r),
2776                              r->claim_value(), _claim_value);
2777       ++_failures;
2778     }
2779     if (!r->isHumongous()) {
2780       _sh_region = NULL;
2781     } else if (r->startsHumongous()) {
2782       _sh_region = r;
2783     } else if (r->continuesHumongous()) {
2784       if (r->humongous_start_region() != _sh_region) {
2785         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2786                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2787                                HR_FORMAT_PARAMS(r),
2788                                r->humongous_start_region(),
2789                                _sh_region);
2790         ++_failures;
2791       }
2792     }
2793     return false;
2794   }
2795   uint failures() { return _failures; }
2796 };
2797 
2798 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2799   CheckClaimValuesClosure cl(claim_value);
2800   heap_region_iterate(&cl);
2801   return cl.failures() == 0;
2802 }
2803 
2804 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2805 private:
2806   jint _claim_value;
2807   uint _failures;
2808 
2809 public:
2810   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2811     _claim_value(claim_value), _failures(0) { }
2812 
2813   uint failures() { return _failures; }
2814 
2815   bool doHeapRegion(HeapRegion* hr) {
2816     assert(hr->in_collection_set(), "how?");
2817     assert(!hr->isHumongous(), "H-region in CSet");
2818     if (hr->claim_value() != _claim_value) {
2819       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2820                              "claim value = %d, should be %d",
2821                              HR_FORMAT_PARAMS(hr),
2822                              hr->claim_value(), _claim_value);
2823       _failures += 1;
2824     }
2825     return false;
2826   }
2827 };
2828 
2829 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2830   CheckClaimValuesInCSetHRClosure cl(claim_value);
2831   collection_set_iterate(&cl);
2832   return cl.failures() == 0;
2833 }
2834 #endif // ASSERT
2835 
2836 // Clear the cached CSet starting regions and (more importantly)
2837 // the time stamps. Called when we reset the GC time stamp.
2838 void G1CollectedHeap::clear_cset_start_regions() {
2839   assert(_worker_cset_start_region != NULL, "sanity");
2840   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2841 
2842   int n_queues = MAX2((int)ParallelGCThreads, 1);
2843   for (int i = 0; i < n_queues; i++) {
2844     _worker_cset_start_region[i] = NULL;
2845     _worker_cset_start_region_time_stamp[i] = 0;
2846   }
2847 }
2848 
2849 // Given the id of a worker, obtain or calculate a suitable
2850 // starting region for iterating over the current collection set.
2851 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2852   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2853 
2854   HeapRegion* result = NULL;
2855   unsigned gc_time_stamp = get_gc_time_stamp();
2856 
2857   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2858     // Cached starting region for current worker was set
2859     // during the current pause - so it's valid.
2860     // Note: the cached starting heap region may be NULL
2861     // (when the collection set is empty).
2862     result = _worker_cset_start_region[worker_i];
2863     assert(result == NULL || result->in_collection_set(), "sanity");
2864     return result;
2865   }
2866 
2867   // The cached entry was not valid so let's calculate
2868   // a suitable starting heap region for this worker.
2869 
2870   // We want the parallel threads to start their collection
2871   // set iteration at different collection set regions to
2872   // avoid contention.
2873   // If we have:
2874   //          n collection set regions
2875   //          p threads
2876   // Then thread t will start at region floor ((t * n) / p)
2877 
2878   result = g1_policy()->collection_set();
2879   if (G1CollectedHeap::use_parallel_gc_threads()) {
2880     uint cs_size = g1_policy()->cset_region_length();
2881     uint active_workers = workers()->active_workers();
2882     assert(UseDynamicNumberOfGCThreads ||
2883              active_workers == workers()->total_workers(),
2884              "Unless dynamic should use total workers");
2885 
2886     uint end_ind   = (cs_size * worker_i) / active_workers;
2887     uint start_ind = 0;
2888 
2889     if (worker_i > 0 &&
2890         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2891       // Previous workers starting region is valid
2892       // so let's iterate from there
2893       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2894       result = _worker_cset_start_region[worker_i - 1];
2895     }
2896 
2897     for (uint i = start_ind; i < end_ind; i++) {
2898       result = result->next_in_collection_set();
2899     }
2900   }
2901 
2902   // Note: the calculated starting heap region may be NULL
2903   // (when the collection set is empty).
2904   assert(result == NULL || result->in_collection_set(), "sanity");
2905   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2906          "should be updated only once per pause");
2907   _worker_cset_start_region[worker_i] = result;
2908   OrderAccess::storestore();
2909   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2910   return result;
2911 }
2912 
2913 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2914                                                      uint no_of_par_workers) {
2915   uint worker_num =
2916            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2917   assert(UseDynamicNumberOfGCThreads ||
2918          no_of_par_workers == workers()->total_workers(),
2919          "Non dynamic should use fixed number of workers");
2920   const uint start_index = n_regions() * worker_i / worker_num;
2921   return region_at(start_index);
2922 }
2923 
2924 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2925   HeapRegion* r = g1_policy()->collection_set();
2926   while (r != NULL) {
2927     HeapRegion* next = r->next_in_collection_set();
2928     if (cl->doHeapRegion(r)) {
2929       cl->incomplete();
2930       return;
2931     }
2932     r = next;
2933   }
2934 }
2935 
2936 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2937                                                   HeapRegionClosure *cl) {
2938   if (r == NULL) {
2939     // The CSet is empty so there's nothing to do.
2940     return;
2941   }
2942 
2943   assert(r->in_collection_set(),
2944          "Start region must be a member of the collection set.");
2945   HeapRegion* cur = r;
2946   while (cur != NULL) {
2947     HeapRegion* next = cur->next_in_collection_set();
2948     if (cl->doHeapRegion(cur) && false) {
2949       cl->incomplete();
2950       return;
2951     }
2952     cur = next;
2953   }
2954   cur = g1_policy()->collection_set();
2955   while (cur != r) {
2956     HeapRegion* next = cur->next_in_collection_set();
2957     if (cl->doHeapRegion(cur) && false) {
2958       cl->incomplete();
2959       return;
2960     }
2961     cur = next;
2962   }
2963 }
2964 
2965 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2966   return n_regions() > 0 ? region_at(0) : NULL;
2967 }
2968 
2969 
2970 Space* G1CollectedHeap::space_containing(const void* addr) const {
2971   Space* res = heap_region_containing(addr);
2972   return res;
2973 }
2974 
2975 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2976   Space* sp = space_containing(addr);
2977   if (sp != NULL) {
2978     return sp->block_start(addr);
2979   }
2980   return NULL;
2981 }
2982 
2983 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2984   Space* sp = space_containing(addr);
2985   assert(sp != NULL, "block_size of address outside of heap");
2986   return sp->block_size(addr);
2987 }
2988 
2989 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2990   Space* sp = space_containing(addr);
2991   return sp->block_is_obj(addr);
2992 }
2993 
2994 bool G1CollectedHeap::supports_tlab_allocation() const {
2995   return true;
2996 }
2997 
2998 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2999   return HeapRegion::GrainBytes;
3000 }
3001 
3002 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3003   // Return the remaining space in the cur alloc region, but not less than
3004   // the min TLAB size.
3005 
3006   // Also, this value can be at most the humongous object threshold,
3007   // since we can't allow tlabs to grow big enough to accommodate
3008   // humongous objects.
3009 
3010   HeapRegion* hr = _mutator_alloc_region.get();
3011   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3012   if (hr == NULL) {
3013     return max_tlab_size;
3014   } else {
3015     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3016   }
3017 }
3018 
3019 size_t G1CollectedHeap::max_capacity() const {
3020   return _g1_reserved.byte_size();
3021 }
3022 
3023 jlong G1CollectedHeap::millis_since_last_gc() {
3024   // assert(false, "NYI");
3025   return 0;
3026 }
3027 
3028 void G1CollectedHeap::prepare_for_verify() {
3029   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3030     ensure_parsability(false);
3031   }
3032   g1_rem_set()->prepare_for_verify();
3033 }
3034 
3035 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3036                                               VerifyOption vo) {
3037   switch (vo) {
3038   case VerifyOption_G1UsePrevMarking:
3039     return hr->obj_allocated_since_prev_marking(obj);
3040   case VerifyOption_G1UseNextMarking:
3041     return hr->obj_allocated_since_next_marking(obj);
3042   case VerifyOption_G1UseMarkWord:
3043     return false;
3044   default:
3045     ShouldNotReachHere();
3046   }
3047   return false; // keep some compilers happy
3048 }
3049 
3050 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3051   switch (vo) {
3052   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3053   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3054   case VerifyOption_G1UseMarkWord:    return NULL;
3055   default:                            ShouldNotReachHere();
3056   }
3057   return NULL; // keep some compilers happy
3058 }
3059 
3060 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3061   switch (vo) {
3062   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3063   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3064   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3065   default:                            ShouldNotReachHere();
3066   }
3067   return false; // keep some compilers happy
3068 }
3069 
3070 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3071   switch (vo) {
3072   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3073   case VerifyOption_G1UseNextMarking: return "NTAMS";
3074   case VerifyOption_G1UseMarkWord:    return "NONE";
3075   default:                            ShouldNotReachHere();
3076   }
3077   return NULL; // keep some compilers happy
3078 }
3079 
3080 class VerifyRootsClosure: public OopClosure {
3081 private:
3082   G1CollectedHeap* _g1h;
3083   VerifyOption     _vo;
3084   bool             _failures;
3085 public:
3086   // _vo == UsePrevMarking -> use "prev" marking information,
3087   // _vo == UseNextMarking -> use "next" marking information,
3088   // _vo == UseMarkWord    -> use mark word from object header.
3089   VerifyRootsClosure(VerifyOption vo) :
3090     _g1h(G1CollectedHeap::heap()),
3091     _vo(vo),
3092     _failures(false) { }
3093 
3094   bool failures() { return _failures; }
3095 
3096   template <class T> void do_oop_nv(T* p) {
3097     T heap_oop = oopDesc::load_heap_oop(p);
3098     if (!oopDesc::is_null(heap_oop)) {
3099       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3100       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3101         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3102                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3103         if (_vo == VerifyOption_G1UseMarkWord) {
3104           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3105         }
3106         obj->print_on(gclog_or_tty);
3107         _failures = true;
3108       }
3109     }
3110   }
3111 
3112   void do_oop(oop* p)       { do_oop_nv(p); }
3113   void do_oop(narrowOop* p) { do_oop_nv(p); }
3114 };
3115 
3116 class G1VerifyCodeRootOopClosure: public OopClosure {
3117   G1CollectedHeap* _g1h;
3118   OopClosure* _root_cl;
3119   nmethod* _nm;
3120   VerifyOption _vo;
3121   bool _failures;
3122 
3123   template <class T> void do_oop_work(T* p) {
3124     // First verify that this root is live
3125     _root_cl->do_oop(p);
3126 
3127     if (!G1VerifyHeapRegionCodeRoots) {
3128       // We're not verifying the code roots attached to heap region.
3129       return;
3130     }
3131 
3132     // Don't check the code roots during marking verification in a full GC
3133     if (_vo == VerifyOption_G1UseMarkWord) {
3134       return;
3135     }
3136 
3137     // Now verify that the current nmethod (which contains p) is
3138     // in the code root list of the heap region containing the
3139     // object referenced by p.
3140 
3141     T heap_oop = oopDesc::load_heap_oop(p);
3142     if (!oopDesc::is_null(heap_oop)) {
3143       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3144 
3145       // Now fetch the region containing the object
3146       HeapRegion* hr = _g1h->heap_region_containing(obj);
3147       HeapRegionRemSet* hrrs = hr->rem_set();
3148       // Verify that the strong code root list for this region
3149       // contains the nmethod
3150       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3151         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3152                               "from nmethod "PTR_FORMAT" not in strong "
3153                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3154                               p, _nm, hr->bottom(), hr->end());
3155         _failures = true;
3156       }
3157     }
3158   }
3159 
3160 public:
3161   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3162     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3163 
3164   void do_oop(oop* p) { do_oop_work(p); }
3165   void do_oop(narrowOop* p) { do_oop_work(p); }
3166 
3167   void set_nmethod(nmethod* nm) { _nm = nm; }
3168   bool failures() { return _failures; }
3169 };
3170 
3171 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3172   G1VerifyCodeRootOopClosure* _oop_cl;
3173 
3174 public:
3175   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3176     _oop_cl(oop_cl) {}
3177 
3178   void do_code_blob(CodeBlob* cb) {
3179     nmethod* nm = cb->as_nmethod_or_null();
3180     if (nm != NULL) {
3181       _oop_cl->set_nmethod(nm);
3182       nm->oops_do(_oop_cl);
3183     }
3184   }
3185 };
3186 
3187 class YoungRefCounterClosure : public OopClosure {
3188   G1CollectedHeap* _g1h;
3189   int              _count;
3190  public:
3191   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3192   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3193   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3194 
3195   int count() { return _count; }
3196   void reset_count() { _count = 0; };
3197 };
3198 
3199 class VerifyKlassClosure: public KlassClosure {
3200   YoungRefCounterClosure _young_ref_counter_closure;
3201   OopClosure *_oop_closure;
3202  public:
3203   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3204   void do_klass(Klass* k) {
3205     k->oops_do(_oop_closure);
3206 
3207     _young_ref_counter_closure.reset_count();
3208     k->oops_do(&_young_ref_counter_closure);
3209     if (_young_ref_counter_closure.count() > 0) {
3210       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3211     }
3212   }
3213 };
3214 
3215 class VerifyLivenessOopClosure: public OopClosure {
3216   G1CollectedHeap* _g1h;
3217   VerifyOption _vo;
3218 public:
3219   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3220     _g1h(g1h), _vo(vo)
3221   { }
3222   void do_oop(narrowOop *p) { do_oop_work(p); }
3223   void do_oop(      oop *p) { do_oop_work(p); }
3224 
3225   template <class T> void do_oop_work(T *p) {
3226     oop obj = oopDesc::load_decode_heap_oop(p);
3227     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3228               "Dead object referenced by a not dead object");
3229   }
3230 };
3231 
3232 class VerifyObjsInRegionClosure: public ObjectClosure {
3233 private:
3234   G1CollectedHeap* _g1h;
3235   size_t _live_bytes;
3236   HeapRegion *_hr;
3237   VerifyOption _vo;
3238 public:
3239   // _vo == UsePrevMarking -> use "prev" marking information,
3240   // _vo == UseNextMarking -> use "next" marking information,
3241   // _vo == UseMarkWord    -> use mark word from object header.
3242   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3243     : _live_bytes(0), _hr(hr), _vo(vo) {
3244     _g1h = G1CollectedHeap::heap();
3245   }
3246   void do_object(oop o) {
3247     VerifyLivenessOopClosure isLive(_g1h, _vo);
3248     assert(o != NULL, "Huh?");
3249     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3250       // If the object is alive according to the mark word,
3251       // then verify that the marking information agrees.
3252       // Note we can't verify the contra-positive of the
3253       // above: if the object is dead (according to the mark
3254       // word), it may not be marked, or may have been marked
3255       // but has since became dead, or may have been allocated
3256       // since the last marking.
3257       if (_vo == VerifyOption_G1UseMarkWord) {
3258         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3259       }
3260 
3261       o->oop_iterate_no_header(&isLive);
3262       if (!_hr->obj_allocated_since_prev_marking(o)) {
3263         size_t obj_size = o->size();    // Make sure we don't overflow
3264         _live_bytes += (obj_size * HeapWordSize);
3265       }
3266     }
3267   }
3268   size_t live_bytes() { return _live_bytes; }
3269 };
3270 
3271 class PrintObjsInRegionClosure : public ObjectClosure {
3272   HeapRegion *_hr;
3273   G1CollectedHeap *_g1;
3274 public:
3275   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3276     _g1 = G1CollectedHeap::heap();
3277   };
3278 
3279   void do_object(oop o) {
3280     if (o != NULL) {
3281       HeapWord *start = (HeapWord *) o;
3282       size_t word_sz = o->size();
3283       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3284                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3285                           (void*) o, word_sz,
3286                           _g1->isMarkedPrev(o),
3287                           _g1->isMarkedNext(o),
3288                           _hr->obj_allocated_since_prev_marking(o));
3289       HeapWord *end = start + word_sz;
3290       HeapWord *cur;
3291       int *val;
3292       for (cur = start; cur < end; cur++) {
3293         val = (int *) cur;
3294         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3295       }
3296     }
3297   }
3298 };
3299 
3300 class VerifyRegionClosure: public HeapRegionClosure {
3301 private:
3302   bool             _par;
3303   VerifyOption     _vo;
3304   bool             _failures;
3305 public:
3306   // _vo == UsePrevMarking -> use "prev" marking information,
3307   // _vo == UseNextMarking -> use "next" marking information,
3308   // _vo == UseMarkWord    -> use mark word from object header.
3309   VerifyRegionClosure(bool par, VerifyOption vo)
3310     : _par(par),
3311       _vo(vo),
3312       _failures(false) {}
3313 
3314   bool failures() {
3315     return _failures;
3316   }
3317 
3318   bool doHeapRegion(HeapRegion* r) {
3319     if (!r->continuesHumongous()) {
3320       bool failures = false;
3321       r->verify(_vo, &failures);
3322       if (failures) {
3323         _failures = true;
3324       } else {
3325         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3326         r->object_iterate(&not_dead_yet_cl);
3327         if (_vo != VerifyOption_G1UseNextMarking) {
3328           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3329             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3330                                    "max_live_bytes "SIZE_FORMAT" "
3331                                    "< calculated "SIZE_FORMAT,
3332                                    r->bottom(), r->end(),
3333                                    r->max_live_bytes(),
3334                                  not_dead_yet_cl.live_bytes());
3335             _failures = true;
3336           }
3337         } else {
3338           // When vo == UseNextMarking we cannot currently do a sanity
3339           // check on the live bytes as the calculation has not been
3340           // finalized yet.
3341         }
3342       }
3343     }
3344     return false; // stop the region iteration if we hit a failure
3345   }
3346 };
3347 
3348 // This is the task used for parallel verification of the heap regions
3349 
3350 class G1ParVerifyTask: public AbstractGangTask {
3351 private:
3352   G1CollectedHeap* _g1h;
3353   VerifyOption     _vo;
3354   bool             _failures;
3355 
3356 public:
3357   // _vo == UsePrevMarking -> use "prev" marking information,
3358   // _vo == UseNextMarking -> use "next" marking information,
3359   // _vo == UseMarkWord    -> use mark word from object header.
3360   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3361     AbstractGangTask("Parallel verify task"),
3362     _g1h(g1h),
3363     _vo(vo),
3364     _failures(false) { }
3365 
3366   bool failures() {
3367     return _failures;
3368   }
3369 
3370   void work(uint worker_id) {
3371     HandleMark hm;
3372     VerifyRegionClosure blk(true, _vo);
3373     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3374                                           _g1h->workers()->active_workers(),
3375                                           HeapRegion::ParVerifyClaimValue);
3376     if (blk.failures()) {
3377       _failures = true;
3378     }
3379   }
3380 };
3381 
3382 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3383   if (SafepointSynchronize::is_at_safepoint()) {
3384     assert(Thread::current()->is_VM_thread(),
3385            "Expected to be executed serially by the VM thread at this point");
3386 
3387     if (!silent) { gclog_or_tty->print("Roots "); }
3388     VerifyRootsClosure rootsCl(vo);
3389     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3390     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3391     VerifyKlassClosure klassCl(this, &rootsCl);
3392 
3393     // We apply the relevant closures to all the oops in the
3394     // system dictionary, the string table and the code cache.
3395     const int so = SO_AllClasses | SO_Strings | SO_AllCodeCache;
3396 
3397     // Need cleared claim bits for the strong roots processing
3398     ClassLoaderDataGraph::clear_claimed_marks();
3399 
3400     process_strong_roots(true,      // activate StrongRootsScope
3401                          ScanningOption(so),  // roots scanning options
3402                          &rootsCl,
3403                          &blobsCl,
3404                          &klassCl
3405                          );
3406 
3407     bool failures = rootsCl.failures() || codeRootsCl.failures();
3408 
3409     if (vo != VerifyOption_G1UseMarkWord) {
3410       // If we're verifying during a full GC then the region sets
3411       // will have been torn down at the start of the GC. Therefore
3412       // verifying the region sets will fail. So we only verify
3413       // the region sets when not in a full GC.
3414       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3415       verify_region_sets();
3416     }
3417 
3418     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3419     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3420       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3421              "sanity check");
3422 
3423       G1ParVerifyTask task(this, vo);
3424       assert(UseDynamicNumberOfGCThreads ||
3425         workers()->active_workers() == workers()->total_workers(),
3426         "If not dynamic should be using all the workers");
3427       int n_workers = workers()->active_workers();
3428       set_par_threads(n_workers);
3429       workers()->run_task(&task);
3430       set_par_threads(0);
3431       if (task.failures()) {
3432         failures = true;
3433       }
3434 
3435       // Checks that the expected amount of parallel work was done.
3436       // The implication is that n_workers is > 0.
3437       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3438              "sanity check");
3439 
3440       reset_heap_region_claim_values();
3441 
3442       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3443              "sanity check");
3444     } else {
3445       VerifyRegionClosure blk(false, vo);
3446       heap_region_iterate(&blk);
3447       if (blk.failures()) {
3448         failures = true;
3449       }
3450     }
3451     if (!silent) gclog_or_tty->print("RemSet ");
3452     rem_set()->verify();
3453 
3454     if (failures) {
3455       gclog_or_tty->print_cr("Heap:");
3456       // It helps to have the per-region information in the output to
3457       // help us track down what went wrong. This is why we call
3458       // print_extended_on() instead of print_on().
3459       print_extended_on(gclog_or_tty);
3460       gclog_or_tty->print_cr("");
3461 #ifndef PRODUCT
3462       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3463         concurrent_mark()->print_reachable("at-verification-failure",
3464                                            vo, false /* all */);
3465       }
3466 #endif
3467       gclog_or_tty->flush();
3468     }
3469     guarantee(!failures, "there should not have been any failures");
3470   } else {
3471     if (!silent)
3472       gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3473   }
3474 }
3475 
3476 void G1CollectedHeap::verify(bool silent) {
3477   verify(silent, VerifyOption_G1UsePrevMarking);
3478 }
3479 
3480 double G1CollectedHeap::verify(bool guard, const char* msg) {
3481   double verify_time_ms = 0.0;
3482 
3483   if (guard && total_collections() >= VerifyGCStartAt) {
3484     double verify_start = os::elapsedTime();
3485     HandleMark hm;  // Discard invalid handles created during verification
3486     prepare_for_verify();
3487     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3488     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3489   }
3490 
3491   return verify_time_ms;
3492 }
3493 
3494 void G1CollectedHeap::verify_before_gc() {
3495   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3496   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3497 }
3498 
3499 void G1CollectedHeap::verify_after_gc() {
3500   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3501   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3502 }
3503 
3504 class PrintRegionClosure: public HeapRegionClosure {
3505   outputStream* _st;
3506 public:
3507   PrintRegionClosure(outputStream* st) : _st(st) {}
3508   bool doHeapRegion(HeapRegion* r) {
3509     r->print_on(_st);
3510     return false;
3511   }
3512 };
3513 
3514 void G1CollectedHeap::print_on(outputStream* st) const {
3515   st->print(" %-20s", "garbage-first heap");
3516   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3517             capacity()/K, used_unlocked()/K);
3518   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3519             _g1_storage.low_boundary(),
3520             _g1_storage.high(),
3521             _g1_storage.high_boundary());
3522   st->cr();
3523   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3524   uint young_regions = _young_list->length();
3525   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3526             (size_t) young_regions * HeapRegion::GrainBytes / K);
3527   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3528   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3529             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3530   st->cr();
3531   MetaspaceAux::print_on(st);
3532 }
3533 
3534 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3535   print_on(st);
3536 
3537   // Print the per-region information.
3538   st->cr();
3539   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3540                "HS=humongous(starts), HC=humongous(continues), "
3541                "CS=collection set, F=free, TS=gc time stamp, "
3542                "PTAMS=previous top-at-mark-start, "
3543                "NTAMS=next top-at-mark-start)");
3544   PrintRegionClosure blk(st);
3545   heap_region_iterate(&blk);
3546 }
3547 
3548 void G1CollectedHeap::print_on_error(outputStream* st) const {
3549   this->CollectedHeap::print_on_error(st);
3550 
3551   if (_cm != NULL) {
3552     st->cr();
3553     _cm->print_on_error(st);
3554   }
3555 }
3556 
3557 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3558   if (G1CollectedHeap::use_parallel_gc_threads()) {
3559     workers()->print_worker_threads_on(st);
3560   }
3561   _cmThread->print_on(st);
3562   st->cr();
3563   _cm->print_worker_threads_on(st);
3564   _cg1r->print_worker_threads_on(st);
3565 }
3566 
3567 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3568   if (G1CollectedHeap::use_parallel_gc_threads()) {
3569     workers()->threads_do(tc);
3570   }
3571   tc->do_thread(_cmThread);
3572   _cg1r->threads_do(tc);
3573 }
3574 
3575 void G1CollectedHeap::print_tracing_info() const {
3576   // We'll overload this to mean "trace GC pause statistics."
3577   if (TraceGen0Time || TraceGen1Time) {
3578     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3579     // to that.
3580     g1_policy()->print_tracing_info();
3581   }
3582   if (G1SummarizeRSetStats) {
3583     g1_rem_set()->print_summary_info();
3584   }
3585   if (G1SummarizeConcMark) {
3586     concurrent_mark()->print_summary_info();
3587   }
3588   g1_policy()->print_yg_surv_rate_info();
3589   SpecializationStats::print();
3590 }
3591 
3592 #ifndef PRODUCT
3593 // Helpful for debugging RSet issues.
3594 
3595 class PrintRSetsClosure : public HeapRegionClosure {
3596 private:
3597   const char* _msg;
3598   size_t _occupied_sum;
3599 
3600 public:
3601   bool doHeapRegion(HeapRegion* r) {
3602     HeapRegionRemSet* hrrs = r->rem_set();
3603     size_t occupied = hrrs->occupied();
3604     _occupied_sum += occupied;
3605 
3606     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3607                            HR_FORMAT_PARAMS(r));
3608     if (occupied == 0) {
3609       gclog_or_tty->print_cr("  RSet is empty");
3610     } else {
3611       hrrs->print();
3612     }
3613     gclog_or_tty->print_cr("----------");
3614     return false;
3615   }
3616 
3617   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3618     gclog_or_tty->cr();
3619     gclog_or_tty->print_cr("========================================");
3620     gclog_or_tty->print_cr(msg);
3621     gclog_or_tty->cr();
3622   }
3623 
3624   ~PrintRSetsClosure() {
3625     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3626     gclog_or_tty->print_cr("========================================");
3627     gclog_or_tty->cr();
3628   }
3629 };
3630 
3631 void G1CollectedHeap::print_cset_rsets() {
3632   PrintRSetsClosure cl("Printing CSet RSets");
3633   collection_set_iterate(&cl);
3634 }
3635 
3636 void G1CollectedHeap::print_all_rsets() {
3637   PrintRSetsClosure cl("Printing All RSets");;
3638   heap_region_iterate(&cl);
3639 }
3640 #endif // PRODUCT
3641 
3642 G1CollectedHeap* G1CollectedHeap::heap() {
3643   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3644          "not a garbage-first heap");
3645   return _g1h;
3646 }
3647 
3648 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3649   // always_do_update_barrier = false;
3650   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3651   // Fill TLAB's and such
3652   ensure_parsability(true);
3653 
3654   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3655       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3656     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3657   }
3658 }
3659 
3660 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3661 
3662   if (G1SummarizeRSetStats &&
3663       (G1SummarizeRSetStatsPeriod > 0) &&
3664       // we are at the end of the GC. Total collections has already been increased.
3665       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3666     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3667   }
3668 
3669   // FIXME: what is this about?
3670   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3671   // is set.
3672   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3673                         "derived pointer present"));
3674   // always_do_update_barrier = true;
3675 
3676   // We have just completed a GC. Update the soft reference
3677   // policy with the new heap occupancy
3678   Universe::update_heap_info_at_gc();
3679 }
3680 
3681 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3682                                                unsigned int gc_count_before,
3683                                                bool* succeeded,
3684                                                GCCause::Cause gc_cause) {
3685   assert_heap_not_locked_and_not_at_safepoint();
3686   g1_policy()->record_stop_world_start();
3687   VM_G1IncCollectionPause op(gc_count_before,
3688                              word_size,
3689                              false, /* should_initiate_conc_mark */
3690                              g1_policy()->max_pause_time_ms(),
3691                              gc_cause);
3692   VMThread::execute(&op);
3693 
3694   HeapWord* result = op.result();
3695   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3696   assert(result == NULL || ret_succeeded,
3697          "the result should be NULL if the VM did not succeed");
3698   *succeeded = ret_succeeded;
3699 
3700   assert_heap_not_locked();
3701   return result;
3702 }
3703 
3704 void
3705 G1CollectedHeap::doConcurrentMark() {
3706   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3707   if (!_cmThread->in_progress()) {
3708     _cmThread->set_started();
3709     CGC_lock->notify();
3710   }
3711 }
3712 
3713 size_t G1CollectedHeap::pending_card_num() {
3714   size_t extra_cards = 0;
3715   JavaThread *curr = Threads::first();
3716   while (curr != NULL) {
3717     DirtyCardQueue& dcq = curr->dirty_card_queue();
3718     extra_cards += dcq.size();
3719     curr = curr->next();
3720   }
3721   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3722   size_t buffer_size = dcqs.buffer_size();
3723   size_t buffer_num = dcqs.completed_buffers_num();
3724 
3725   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3726   // in bytes - not the number of 'entries'. We need to convert
3727   // into a number of cards.
3728   return (buffer_size * buffer_num + extra_cards) / oopSize;
3729 }
3730 
3731 size_t G1CollectedHeap::cards_scanned() {
3732   return g1_rem_set()->cardsScanned();
3733 }
3734 
3735 void
3736 G1CollectedHeap::setup_surviving_young_words() {
3737   assert(_surviving_young_words == NULL, "pre-condition");
3738   uint array_length = g1_policy()->young_cset_region_length();
3739   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3740   if (_surviving_young_words == NULL) {
3741     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3742                           "Not enough space for young surv words summary.");
3743   }
3744   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3745 #ifdef ASSERT
3746   for (uint i = 0;  i < array_length; ++i) {
3747     assert( _surviving_young_words[i] == 0, "memset above" );
3748   }
3749 #endif // !ASSERT
3750 }
3751 
3752 void
3753 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3754   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3755   uint array_length = g1_policy()->young_cset_region_length();
3756   for (uint i = 0; i < array_length; ++i) {
3757     _surviving_young_words[i] += surv_young_words[i];
3758   }
3759 }
3760 
3761 void
3762 G1CollectedHeap::cleanup_surviving_young_words() {
3763   guarantee( _surviving_young_words != NULL, "pre-condition" );
3764   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3765   _surviving_young_words = NULL;
3766 }
3767 
3768 #ifdef ASSERT
3769 class VerifyCSetClosure: public HeapRegionClosure {
3770 public:
3771   bool doHeapRegion(HeapRegion* hr) {
3772     // Here we check that the CSet region's RSet is ready for parallel
3773     // iteration. The fields that we'll verify are only manipulated
3774     // when the region is part of a CSet and is collected. Afterwards,
3775     // we reset these fields when we clear the region's RSet (when the
3776     // region is freed) so they are ready when the region is
3777     // re-allocated. The only exception to this is if there's an
3778     // evacuation failure and instead of freeing the region we leave
3779     // it in the heap. In that case, we reset these fields during
3780     // evacuation failure handling.
3781     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3782 
3783     // Here's a good place to add any other checks we'd like to
3784     // perform on CSet regions.
3785     return false;
3786   }
3787 };
3788 #endif // ASSERT
3789 
3790 #if TASKQUEUE_STATS
3791 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3792   st->print_raw_cr("GC Task Stats");
3793   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3794   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3795 }
3796 
3797 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3798   print_taskqueue_stats_hdr(st);
3799 
3800   TaskQueueStats totals;
3801   const int n = workers() != NULL ? workers()->total_workers() : 1;
3802   for (int i = 0; i < n; ++i) {
3803     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3804     totals += task_queue(i)->stats;
3805   }
3806   st->print_raw("tot "); totals.print(st); st->cr();
3807 
3808   DEBUG_ONLY(totals.verify());
3809 }
3810 
3811 void G1CollectedHeap::reset_taskqueue_stats() {
3812   const int n = workers() != NULL ? workers()->total_workers() : 1;
3813   for (int i = 0; i < n; ++i) {
3814     task_queue(i)->stats.reset();
3815   }
3816 }
3817 #endif // TASKQUEUE_STATS
3818 
3819 void G1CollectedHeap::log_gc_header() {
3820   if (!G1Log::fine()) {
3821     return;
3822   }
3823 
3824   gclog_or_tty->date_stamp(PrintGCDateStamps);
3825   gclog_or_tty->stamp(PrintGCTimeStamps);
3826 
3827   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3828     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3829     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3830 
3831   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3832 }
3833 
3834 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3835   if (!G1Log::fine()) {
3836     return;
3837   }
3838 
3839   if (G1Log::finer()) {
3840     if (evacuation_failed()) {
3841       gclog_or_tty->print(" (to-space exhausted)");
3842     }
3843     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3844     g1_policy()->phase_times()->note_gc_end();
3845     g1_policy()->phase_times()->print(pause_time_sec);
3846     g1_policy()->print_detailed_heap_transition();
3847   } else {
3848     if (evacuation_failed()) {
3849       gclog_or_tty->print("--");
3850     }
3851     g1_policy()->print_heap_transition();
3852     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3853   }
3854   gclog_or_tty->flush();
3855 }
3856 
3857 bool
3858 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3859   assert_at_safepoint(true /* should_be_vm_thread */);
3860   guarantee(!is_gc_active(), "collection is not reentrant");
3861 
3862   if (GC_locker::check_active_before_gc()) {
3863     return false;
3864   }
3865 
3866   _gc_timer_stw->register_gc_start();
3867 
3868   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3869 
3870   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3871   ResourceMark rm;
3872 
3873   print_heap_before_gc();
3874   trace_heap_before_gc(_gc_tracer_stw);
3875 
3876   HRSPhaseSetter x(HRSPhaseEvacuation);
3877   verify_region_sets_optional();
3878   verify_dirty_young_regions();
3879 
3880   // This call will decide whether this pause is an initial-mark
3881   // pause. If it is, during_initial_mark_pause() will return true
3882   // for the duration of this pause.
3883   g1_policy()->decide_on_conc_mark_initiation();
3884 
3885   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3886   assert(!g1_policy()->during_initial_mark_pause() ||
3887           g1_policy()->gcs_are_young(), "sanity");
3888 
3889   // We also do not allow mixed GCs during marking.
3890   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3891 
3892   // Record whether this pause is an initial mark. When the current
3893   // thread has completed its logging output and it's safe to signal
3894   // the CM thread, the flag's value in the policy has been reset.
3895   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3896 
3897   // Inner scope for scope based logging, timers, and stats collection
3898   {
3899     EvacuationInfo evacuation_info;
3900 
3901     if (g1_policy()->during_initial_mark_pause()) {
3902       // We are about to start a marking cycle, so we increment the
3903       // full collection counter.
3904       increment_old_marking_cycles_started();
3905       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3906     }
3907 
3908     _gc_tracer_stw->report_yc_type(yc_type());
3909 
3910     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3911 
3912     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3913                                 workers()->active_workers() : 1);
3914     double pause_start_sec = os::elapsedTime();
3915     g1_policy()->phase_times()->note_gc_start(active_workers);
3916     log_gc_header();
3917 
3918     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3919     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3920 
3921     // If the secondary_free_list is not empty, append it to the
3922     // free_list. No need to wait for the cleanup operation to finish;
3923     // the region allocation code will check the secondary_free_list
3924     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3925     // set, skip this step so that the region allocation code has to
3926     // get entries from the secondary_free_list.
3927     if (!G1StressConcRegionFreeing) {
3928       append_secondary_free_list_if_not_empty_with_lock();
3929     }
3930 
3931     assert(check_young_list_well_formed(), "young list should be well formed");
3932     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3933            "sanity check");
3934 
3935     // Don't dynamically change the number of GC threads this early.  A value of
3936     // 0 is used to indicate serial work.  When parallel work is done,
3937     // it will be set.
3938 
3939     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3940       IsGCActiveMark x;
3941 
3942       gc_prologue(false);
3943       increment_total_collections(false /* full gc */);
3944       increment_gc_time_stamp();
3945 
3946       verify_before_gc();
3947 
3948       COMPILER2_PRESENT(DerivedPointerTable::clear());
3949 
3950       // Please see comment in g1CollectedHeap.hpp and
3951       // G1CollectedHeap::ref_processing_init() to see how
3952       // reference processing currently works in G1.
3953 
3954       // Enable discovery in the STW reference processor
3955       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3956                                             true /*verify_no_refs*/);
3957 
3958       {
3959         // We want to temporarily turn off discovery by the
3960         // CM ref processor, if necessary, and turn it back on
3961         // on again later if we do. Using a scoped
3962         // NoRefDiscovery object will do this.
3963         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3964 
3965         // Forget the current alloc region (we might even choose it to be part
3966         // of the collection set!).
3967         release_mutator_alloc_region();
3968 
3969         // We should call this after we retire the mutator alloc
3970         // region(s) so that all the ALLOC / RETIRE events are generated
3971         // before the start GC event.
3972         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3973 
3974         // This timing is only used by the ergonomics to handle our pause target.
3975         // It is unclear why this should not include the full pause. We will
3976         // investigate this in CR 7178365.
3977         //
3978         // Preserving the old comment here if that helps the investigation:
3979         //
3980         // The elapsed time induced by the start time below deliberately elides
3981         // the possible verification above.
3982         double sample_start_time_sec = os::elapsedTime();
3983 
3984 #if YOUNG_LIST_VERBOSE
3985         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3986         _young_list->print();
3987         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3988 #endif // YOUNG_LIST_VERBOSE
3989 
3990         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3991 
3992         double scan_wait_start = os::elapsedTime();
3993         // We have to wait until the CM threads finish scanning the
3994         // root regions as it's the only way to ensure that all the
3995         // objects on them have been correctly scanned before we start
3996         // moving them during the GC.
3997         bool waited = _cm->root_regions()->wait_until_scan_finished();
3998         double wait_time_ms = 0.0;
3999         if (waited) {
4000           double scan_wait_end = os::elapsedTime();
4001           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4002         }
4003         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4004 
4005 #if YOUNG_LIST_VERBOSE
4006         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4007         _young_list->print();
4008 #endif // YOUNG_LIST_VERBOSE
4009 
4010         if (g1_policy()->during_initial_mark_pause()) {
4011           concurrent_mark()->checkpointRootsInitialPre();
4012         }
4013 
4014 #if YOUNG_LIST_VERBOSE
4015         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4016         _young_list->print();
4017         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4018 #endif // YOUNG_LIST_VERBOSE
4019 
4020         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4021 
4022         _cm->note_start_of_gc();
4023         // We should not verify the per-thread SATB buffers given that
4024         // we have not filtered them yet (we'll do so during the
4025         // GC). We also call this after finalize_cset() to
4026         // ensure that the CSet has been finalized.
4027         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4028                                  true  /* verify_enqueued_buffers */,
4029                                  false /* verify_thread_buffers */,
4030                                  true  /* verify_fingers */);
4031 
4032         if (_hr_printer.is_active()) {
4033           HeapRegion* hr = g1_policy()->collection_set();
4034           while (hr != NULL) {
4035             G1HRPrinter::RegionType type;
4036             if (!hr->is_young()) {
4037               type = G1HRPrinter::Old;
4038             } else if (hr->is_survivor()) {
4039               type = G1HRPrinter::Survivor;
4040             } else {
4041               type = G1HRPrinter::Eden;
4042             }
4043             _hr_printer.cset(hr);
4044             hr = hr->next_in_collection_set();
4045           }
4046         }
4047 
4048 #ifdef ASSERT
4049         VerifyCSetClosure cl;
4050         collection_set_iterate(&cl);
4051 #endif // ASSERT
4052 
4053         setup_surviving_young_words();
4054 
4055         // Initialize the GC alloc regions.
4056         init_gc_alloc_regions(evacuation_info);
4057 
4058         // Actually do the work...
4059         evacuate_collection_set(evacuation_info);
4060 
4061         // We do this to mainly verify the per-thread SATB buffers
4062         // (which have been filtered by now) since we didn't verify
4063         // them earlier. No point in re-checking the stacks / enqueued
4064         // buffers given that the CSet has not changed since last time
4065         // we checked.
4066         _cm->verify_no_cset_oops(false /* verify_stacks */,
4067                                  false /* verify_enqueued_buffers */,
4068                                  true  /* verify_thread_buffers */,
4069                                  true  /* verify_fingers */);
4070 
4071         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4072         g1_policy()->clear_collection_set();
4073 
4074         cleanup_surviving_young_words();
4075 
4076         // Start a new incremental collection set for the next pause.
4077         g1_policy()->start_incremental_cset_building();
4078 
4079         // Clear the _cset_fast_test bitmap in anticipation of adding
4080         // regions to the incremental collection set for the next
4081         // evacuation pause.
4082         clear_cset_fast_test();
4083 
4084         _young_list->reset_sampled_info();
4085 
4086         // Don't check the whole heap at this point as the
4087         // GC alloc regions from this pause have been tagged
4088         // as survivors and moved on to the survivor list.
4089         // Survivor regions will fail the !is_young() check.
4090         assert(check_young_list_empty(false /* check_heap */),
4091           "young list should be empty");
4092 
4093 #if YOUNG_LIST_VERBOSE
4094         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4095         _young_list->print();
4096 #endif // YOUNG_LIST_VERBOSE
4097 
4098         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4099                                              _young_list->first_survivor_region(),
4100                                              _young_list->last_survivor_region());
4101 
4102         _young_list->reset_auxilary_lists();
4103 
4104         if (evacuation_failed()) {
4105           _summary_bytes_used = recalculate_used();
4106           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4107           for (uint i = 0; i < n_queues; i++) {
4108             if (_evacuation_failed_info_array[i].has_failed()) {
4109               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4110             }
4111           }
4112         } else {
4113           // The "used" of the the collection set have already been subtracted
4114           // when they were freed.  Add in the bytes evacuated.
4115           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4116         }
4117 
4118         if (g1_policy()->during_initial_mark_pause()) {
4119           // We have to do this before we notify the CM threads that
4120           // they can start working to make sure that all the
4121           // appropriate initialization is done on the CM object.
4122           concurrent_mark()->checkpointRootsInitialPost();
4123           set_marking_started();
4124           // Note that we don't actually trigger the CM thread at
4125           // this point. We do that later when we're sure that
4126           // the current thread has completed its logging output.
4127         }
4128 
4129         allocate_dummy_regions();
4130 
4131 #if YOUNG_LIST_VERBOSE
4132         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4133         _young_list->print();
4134         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4135 #endif // YOUNG_LIST_VERBOSE
4136 
4137         init_mutator_alloc_region();
4138 
4139         {
4140           size_t expand_bytes = g1_policy()->expansion_amount();
4141           if (expand_bytes > 0) {
4142             size_t bytes_before = capacity();
4143             // No need for an ergo verbose message here,
4144             // expansion_amount() does this when it returns a value > 0.
4145             if (!expand(expand_bytes)) {
4146               // We failed to expand the heap so let's verify that
4147               // committed/uncommitted amount match the backing store
4148               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4149               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4150             }
4151           }
4152         }
4153 
4154         // We redo the verification but now wrt to the new CSet which
4155         // has just got initialized after the previous CSet was freed.
4156         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4157                                  true  /* verify_enqueued_buffers */,
4158                                  true  /* verify_thread_buffers */,
4159                                  true  /* verify_fingers */);
4160         _cm->note_end_of_gc();
4161 
4162         // This timing is only used by the ergonomics to handle our pause target.
4163         // It is unclear why this should not include the full pause. We will
4164         // investigate this in CR 7178365.
4165         double sample_end_time_sec = os::elapsedTime();
4166         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4167         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4168 
4169         MemoryService::track_memory_usage();
4170 
4171         // In prepare_for_verify() below we'll need to scan the deferred
4172         // update buffers to bring the RSets up-to-date if
4173         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4174         // the update buffers we'll probably need to scan cards on the
4175         // regions we just allocated to (i.e., the GC alloc
4176         // regions). However, during the last GC we called
4177         // set_saved_mark() on all the GC alloc regions, so card
4178         // scanning might skip the [saved_mark_word()...top()] area of
4179         // those regions (i.e., the area we allocated objects into
4180         // during the last GC). But it shouldn't. Given that
4181         // saved_mark_word() is conditional on whether the GC time stamp
4182         // on the region is current or not, by incrementing the GC time
4183         // stamp here we invalidate all the GC time stamps on all the
4184         // regions and saved_mark_word() will simply return top() for
4185         // all the regions. This is a nicer way of ensuring this rather
4186         // than iterating over the regions and fixing them. In fact, the
4187         // GC time stamp increment here also ensures that
4188         // saved_mark_word() will return top() between pauses, i.e.,
4189         // during concurrent refinement. So we don't need the
4190         // is_gc_active() check to decided which top to use when
4191         // scanning cards (see CR 7039627).
4192         increment_gc_time_stamp();
4193 
4194         verify_after_gc();
4195 
4196         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4197         ref_processor_stw()->verify_no_references_recorded();
4198 
4199         // CM reference discovery will be re-enabled if necessary.
4200       }
4201 
4202       // We should do this after we potentially expand the heap so
4203       // that all the COMMIT events are generated before the end GC
4204       // event, and after we retire the GC alloc regions so that all
4205       // RETIRE events are generated before the end GC event.
4206       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4207 
4208       if (mark_in_progress()) {
4209         concurrent_mark()->update_g1_committed();
4210       }
4211 
4212 #ifdef TRACESPINNING
4213       ParallelTaskTerminator::print_termination_counts();
4214 #endif
4215 
4216       gc_epilogue(false);
4217     }
4218 
4219     // Print the remainder of the GC log output.
4220     log_gc_footer(os::elapsedTime() - pause_start_sec);
4221 
4222     // It is not yet to safe to tell the concurrent mark to
4223     // start as we have some optional output below. We don't want the
4224     // output from the concurrent mark thread interfering with this
4225     // logging output either.
4226 
4227     _hrs.verify_optional();
4228     verify_region_sets_optional();
4229 
4230     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4231     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4232 
4233     print_heap_after_gc();
4234     trace_heap_after_gc(_gc_tracer_stw);
4235 
4236     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4237     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4238     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4239     // before any GC notifications are raised.
4240     g1mm()->update_sizes();
4241 
4242     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4243     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4244     _gc_timer_stw->register_gc_end();
4245     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4246   }
4247   // It should now be safe to tell the concurrent mark thread to start
4248   // without its logging output interfering with the logging output
4249   // that came from the pause.
4250 
4251   if (should_start_conc_mark) {
4252     // CAUTION: after the doConcurrentMark() call below,
4253     // the concurrent marking thread(s) could be running
4254     // concurrently with us. Make sure that anything after
4255     // this point does not assume that we are the only GC thread
4256     // running. Note: of course, the actual marking work will
4257     // not start until the safepoint itself is released in
4258     // ConcurrentGCThread::safepoint_desynchronize().
4259     doConcurrentMark();
4260   }
4261 
4262   return true;
4263 }
4264 
4265 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4266 {
4267   size_t gclab_word_size;
4268   switch (purpose) {
4269     case GCAllocForSurvived:
4270       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4271       break;
4272     case GCAllocForTenured:
4273       gclab_word_size = _old_plab_stats.desired_plab_sz();
4274       break;
4275     default:
4276       assert(false, "unknown GCAllocPurpose");
4277       gclab_word_size = _old_plab_stats.desired_plab_sz();
4278       break;
4279   }
4280 
4281   // Prevent humongous PLAB sizes for two reasons:
4282   // * PLABs are allocated using a similar paths as oops, but should
4283   //   never be in a humongous region
4284   // * Allowing humongous PLABs needlessly churns the region free lists
4285   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4286 }
4287 
4288 void G1CollectedHeap::init_mutator_alloc_region() {
4289   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4290   _mutator_alloc_region.init();
4291 }
4292 
4293 void G1CollectedHeap::release_mutator_alloc_region() {
4294   _mutator_alloc_region.release();
4295   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4296 }
4297 
4298 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4299   assert_at_safepoint(true /* should_be_vm_thread */);
4300 
4301   _survivor_gc_alloc_region.init();
4302   _old_gc_alloc_region.init();
4303   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4304   _retained_old_gc_alloc_region = NULL;
4305 
4306   // We will discard the current GC alloc region if:
4307   // a) it's in the collection set (it can happen!),
4308   // b) it's already full (no point in using it),
4309   // c) it's empty (this means that it was emptied during
4310   // a cleanup and it should be on the free list now), or
4311   // d) it's humongous (this means that it was emptied
4312   // during a cleanup and was added to the free list, but
4313   // has been subsequently used to allocate a humongous
4314   // object that may be less than the region size).
4315   if (retained_region != NULL &&
4316       !retained_region->in_collection_set() &&
4317       !(retained_region->top() == retained_region->end()) &&
4318       !retained_region->is_empty() &&
4319       !retained_region->isHumongous()) {
4320     retained_region->set_saved_mark();
4321     // The retained region was added to the old region set when it was
4322     // retired. We have to remove it now, since we don't allow regions
4323     // we allocate to in the region sets. We'll re-add it later, when
4324     // it's retired again.
4325     _old_set.remove(retained_region);
4326     bool during_im = g1_policy()->during_initial_mark_pause();
4327     retained_region->note_start_of_copying(during_im);
4328     _old_gc_alloc_region.set(retained_region);
4329     _hr_printer.reuse(retained_region);
4330     evacuation_info.set_alloc_regions_used_before(retained_region->used());
4331   }
4332 }
4333 
4334 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4335   evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4336                                          _old_gc_alloc_region.count());
4337   _survivor_gc_alloc_region.release();
4338   // If we have an old GC alloc region to release, we'll save it in
4339   // _retained_old_gc_alloc_region. If we don't
4340   // _retained_old_gc_alloc_region will become NULL. This is what we
4341   // want either way so no reason to check explicitly for either
4342   // condition.
4343   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4344 
4345   if (ResizePLAB) {
4346     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4347     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4348   }
4349 }
4350 
4351 void G1CollectedHeap::abandon_gc_alloc_regions() {
4352   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4353   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4354   _retained_old_gc_alloc_region = NULL;
4355 }
4356 
4357 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4358   _drain_in_progress = false;
4359   set_evac_failure_closure(cl);
4360   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4361 }
4362 
4363 void G1CollectedHeap::finalize_for_evac_failure() {
4364   assert(_evac_failure_scan_stack != NULL &&
4365          _evac_failure_scan_stack->length() == 0,
4366          "Postcondition");
4367   assert(!_drain_in_progress, "Postcondition");
4368   delete _evac_failure_scan_stack;
4369   _evac_failure_scan_stack = NULL;
4370 }
4371 
4372 void G1CollectedHeap::remove_self_forwarding_pointers() {
4373   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4374 
4375   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4376 
4377   if (G1CollectedHeap::use_parallel_gc_threads()) {
4378     set_par_threads();
4379     workers()->run_task(&rsfp_task);
4380     set_par_threads(0);
4381   } else {
4382     rsfp_task.work(0);
4383   }
4384 
4385   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4386 
4387   // Reset the claim values in the regions in the collection set.
4388   reset_cset_heap_region_claim_values();
4389 
4390   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4391 
4392   // Now restore saved marks, if any.
4393   assert(_objs_with_preserved_marks.size() ==
4394             _preserved_marks_of_objs.size(), "Both or none.");
4395   while (!_objs_with_preserved_marks.is_empty()) {
4396     oop obj = _objs_with_preserved_marks.pop();
4397     markOop m = _preserved_marks_of_objs.pop();
4398     obj->set_mark(m);
4399   }
4400   _objs_with_preserved_marks.clear(true);
4401   _preserved_marks_of_objs.clear(true);
4402 }
4403 
4404 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4405   _evac_failure_scan_stack->push(obj);
4406 }
4407 
4408 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4409   assert(_evac_failure_scan_stack != NULL, "precondition");
4410 
4411   while (_evac_failure_scan_stack->length() > 0) {
4412      oop obj = _evac_failure_scan_stack->pop();
4413      _evac_failure_closure->set_region(heap_region_containing(obj));
4414      obj->oop_iterate_backwards(_evac_failure_closure);
4415   }
4416 }
4417 
4418 oop
4419 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4420                                                oop old) {
4421   assert(obj_in_cs(old),
4422          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4423                  (HeapWord*) old));
4424   markOop m = old->mark();
4425   oop forward_ptr = old->forward_to_atomic(old);
4426   if (forward_ptr == NULL) {
4427     // Forward-to-self succeeded.
4428     assert(_par_scan_state != NULL, "par scan state");
4429     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4430     uint queue_num = _par_scan_state->queue_num();
4431 
4432     _evacuation_failed = true;
4433     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4434     if (_evac_failure_closure != cl) {
4435       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4436       assert(!_drain_in_progress,
4437              "Should only be true while someone holds the lock.");
4438       // Set the global evac-failure closure to the current thread's.
4439       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4440       set_evac_failure_closure(cl);
4441       // Now do the common part.
4442       handle_evacuation_failure_common(old, m);
4443       // Reset to NULL.
4444       set_evac_failure_closure(NULL);
4445     } else {
4446       // The lock is already held, and this is recursive.
4447       assert(_drain_in_progress, "This should only be the recursive case.");
4448       handle_evacuation_failure_common(old, m);
4449     }
4450     return old;
4451   } else {
4452     // Forward-to-self failed. Either someone else managed to allocate
4453     // space for this object (old != forward_ptr) or they beat us in
4454     // self-forwarding it (old == forward_ptr).
4455     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4456            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4457                    "should not be in the CSet",
4458                    (HeapWord*) old, (HeapWord*) forward_ptr));
4459     return forward_ptr;
4460   }
4461 }
4462 
4463 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4464   preserve_mark_if_necessary(old, m);
4465 
4466   HeapRegion* r = heap_region_containing(old);
4467   if (!r->evacuation_failed()) {
4468     r->set_evacuation_failed(true);
4469     _hr_printer.evac_failure(r);
4470   }
4471 
4472   push_on_evac_failure_scan_stack(old);
4473 
4474   if (!_drain_in_progress) {
4475     // prevent recursion in copy_to_survivor_space()
4476     _drain_in_progress = true;
4477     drain_evac_failure_scan_stack();
4478     _drain_in_progress = false;
4479   }
4480 }
4481 
4482 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4483   assert(evacuation_failed(), "Oversaving!");
4484   // We want to call the "for_promotion_failure" version only in the
4485   // case of a promotion failure.
4486   if (m->must_be_preserved_for_promotion_failure(obj)) {
4487     _objs_with_preserved_marks.push(obj);
4488     _preserved_marks_of_objs.push(m);
4489   }
4490 }
4491 
4492 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4493                                                   size_t word_size) {
4494   if (purpose == GCAllocForSurvived) {
4495     HeapWord* result = survivor_attempt_allocation(word_size);
4496     if (result != NULL) {
4497       return result;
4498     } else {
4499       // Let's try to allocate in the old gen in case we can fit the
4500       // object there.
4501       return old_attempt_allocation(word_size);
4502     }
4503   } else {
4504     assert(purpose ==  GCAllocForTenured, "sanity");
4505     HeapWord* result = old_attempt_allocation(word_size);
4506     if (result != NULL) {
4507       return result;
4508     } else {
4509       // Let's try to allocate in the survivors in case we can fit the
4510       // object there.
4511       return survivor_attempt_allocation(word_size);
4512     }
4513   }
4514 
4515   ShouldNotReachHere();
4516   // Trying to keep some compilers happy.
4517   return NULL;
4518 }
4519 
4520 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4521   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4522 
4523 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4524   : _g1h(g1h),
4525     _refs(g1h->task_queue(queue_num)),
4526     _dcq(&g1h->dirty_card_queue_set()),
4527     _ct_bs(g1h->g1_barrier_set()),
4528     _g1_rem(g1h->g1_rem_set()),
4529     _hash_seed(17), _queue_num(queue_num),
4530     _term_attempts(0),
4531     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4532     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4533     _age_table(false),
4534     _strong_roots_time(0), _term_time(0),
4535     _alloc_buffer_waste(0), _undo_waste(0) {
4536   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4537   // we "sacrifice" entry 0 to keep track of surviving bytes for
4538   // non-young regions (where the age is -1)
4539   // We also add a few elements at the beginning and at the end in
4540   // an attempt to eliminate cache contention
4541   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4542   uint array_length = PADDING_ELEM_NUM +
4543                       real_length +
4544                       PADDING_ELEM_NUM;
4545   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4546   if (_surviving_young_words_base == NULL)
4547     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4548                           "Not enough space for young surv histo.");
4549   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4550   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4551 
4552   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4553   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4554 
4555   _start = os::elapsedTime();
4556 }
4557 
4558 void
4559 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4560 {
4561   st->print_raw_cr("GC Termination Stats");
4562   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4563                    " ------waste (KiB)------");
4564   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4565                    "  total   alloc    undo");
4566   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4567                    " ------- ------- -------");
4568 }
4569 
4570 void
4571 G1ParScanThreadState::print_termination_stats(int i,
4572                                               outputStream* const st) const
4573 {
4574   const double elapsed_ms = elapsed_time() * 1000.0;
4575   const double s_roots_ms = strong_roots_time() * 1000.0;
4576   const double term_ms    = term_time() * 1000.0;
4577   st->print_cr("%3d %9.2f %9.2f %6.2f "
4578                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4579                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4580                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4581                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4582                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4583                alloc_buffer_waste() * HeapWordSize / K,
4584                undo_waste() * HeapWordSize / K);
4585 }
4586 
4587 #ifdef ASSERT
4588 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4589   assert(ref != NULL, "invariant");
4590   assert(UseCompressedOops, "sanity");
4591   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4592   oop p = oopDesc::load_decode_heap_oop(ref);
4593   assert(_g1h->is_in_g1_reserved(p),
4594          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4595   return true;
4596 }
4597 
4598 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4599   assert(ref != NULL, "invariant");
4600   if (has_partial_array_mask(ref)) {
4601     // Must be in the collection set--it's already been copied.
4602     oop p = clear_partial_array_mask(ref);
4603     assert(_g1h->obj_in_cs(p),
4604            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4605   } else {
4606     oop p = oopDesc::load_decode_heap_oop(ref);
4607     assert(_g1h->is_in_g1_reserved(p),
4608            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4609   }
4610   return true;
4611 }
4612 
4613 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4614   if (ref.is_narrow()) {
4615     return verify_ref((narrowOop*) ref);
4616   } else {
4617     return verify_ref((oop*) ref);
4618   }
4619 }
4620 #endif // ASSERT
4621 
4622 void G1ParScanThreadState::trim_queue() {
4623   assert(_evac_cl != NULL, "not set");
4624   assert(_evac_failure_cl != NULL, "not set");
4625   assert(_partial_scan_cl != NULL, "not set");
4626 
4627   StarTask ref;
4628   do {
4629     // Drain the overflow stack first, so other threads can steal.
4630     while (refs()->pop_overflow(ref)) {
4631       deal_with_reference(ref);
4632     }
4633 
4634     while (refs()->pop_local(ref)) {
4635       deal_with_reference(ref);
4636     }
4637   } while (!refs()->is_empty());
4638 }
4639 
4640 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4641                                      G1ParScanThreadState* par_scan_state) :
4642   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4643   _par_scan_state(par_scan_state),
4644   _worker_id(par_scan_state->queue_num()),
4645   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4646   _mark_in_progress(_g1->mark_in_progress()) { }
4647 
4648 template <G1Barrier barrier, bool do_mark_object>
4649 void G1ParCopyClosure<barrier, do_mark_object>::mark_object(oop obj) {
4650 #ifdef ASSERT
4651   HeapRegion* hr = _g1->heap_region_containing(obj);
4652   assert(hr != NULL, "sanity");
4653   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4654 #endif // ASSERT
4655 
4656   // We know that the object is not moving so it's safe to read its size.
4657   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4658 }
4659 
4660 template <G1Barrier barrier, bool do_mark_object>
4661 void G1ParCopyClosure<barrier, do_mark_object>
4662   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4663 #ifdef ASSERT
4664   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4665   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4666   assert(from_obj != to_obj, "should not be self-forwarded");
4667 
4668   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4669   assert(from_hr != NULL, "sanity");
4670   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4671 
4672   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4673   assert(to_hr != NULL, "sanity");
4674   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4675 #endif // ASSERT
4676 
4677   // The object might be in the process of being copied by another
4678   // worker so we cannot trust that its to-space image is
4679   // well-formed. So we have to read its size from its from-space
4680   // image which we know should not be changing.
4681   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4682 }
4683 
4684 template <G1Barrier barrier, bool do_mark_object>
4685 oop G1ParCopyClosure<barrier, do_mark_object>
4686   ::copy_to_survivor_space(oop old) {
4687   size_t word_sz = old->size();
4688   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4689   // +1 to make the -1 indexes valid...
4690   int       young_index = from_region->young_index_in_cset()+1;
4691   assert( (from_region->is_young() && young_index >  0) ||
4692          (!from_region->is_young() && young_index == 0), "invariant" );
4693   G1CollectorPolicy* g1p = _g1->g1_policy();
4694   markOop m = old->mark();
4695   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4696                                            : m->age();
4697   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4698                                                              word_sz);
4699   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4700 #ifndef PRODUCT
4701   // Should this evacuation fail?
4702   if (_g1->evacuation_should_fail()) {
4703     if (obj_ptr != NULL) {
4704       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4705       obj_ptr = NULL;
4706     }
4707   }
4708 #endif // !PRODUCT
4709 
4710   if (obj_ptr == NULL) {
4711     // This will either forward-to-self, or detect that someone else has
4712     // installed a forwarding pointer.
4713     return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4714   }
4715 
4716   oop obj = oop(obj_ptr);
4717 
4718   // We're going to allocate linearly, so might as well prefetch ahead.
4719   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4720 
4721   oop forward_ptr = old->forward_to_atomic(obj);
4722   if (forward_ptr == NULL) {
4723     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4724     if (g1p->track_object_age(alloc_purpose)) {
4725       // We could simply do obj->incr_age(). However, this causes a
4726       // performance issue. obj->incr_age() will first check whether
4727       // the object has a displaced mark by checking its mark word;
4728       // getting the mark word from the new location of the object
4729       // stalls. So, given that we already have the mark word and we
4730       // are about to install it anyway, it's better to increase the
4731       // age on the mark word, when the object does not have a
4732       // displaced mark word. We're not expecting many objects to have
4733       // a displaced marked word, so that case is not optimized
4734       // further (it could be...) and we simply call obj->incr_age().
4735 
4736       if (m->has_displaced_mark_helper()) {
4737         // in this case, we have to install the mark word first,
4738         // otherwise obj looks to be forwarded (the old mark word,
4739         // which contains the forward pointer, was copied)
4740         obj->set_mark(m);
4741         obj->incr_age();
4742       } else {
4743         m = m->incr_age();
4744         obj->set_mark(m);
4745       }
4746       _par_scan_state->age_table()->add(obj, word_sz);
4747     } else {
4748       obj->set_mark(m);
4749     }
4750 
4751     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4752     surv_young_words[young_index] += word_sz;
4753 
4754     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4755       // We keep track of the next start index in the length field of
4756       // the to-space object. The actual length can be found in the
4757       // length field of the from-space object.
4758       arrayOop(obj)->set_length(0);
4759       oop* old_p = set_partial_array_mask(old);
4760       _par_scan_state->push_on_queue(old_p);
4761     } else {
4762       // No point in using the slower heap_region_containing() method,
4763       // given that we know obj is in the heap.
4764       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4765       obj->oop_iterate_backwards(&_scanner);
4766     }
4767   } else {
4768     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4769     obj = forward_ptr;
4770   }
4771   return obj;
4772 }
4773 
4774 template <class T>
4775 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4776   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4777     _scanned_klass->record_modified_oops();
4778   }
4779 }
4780 
4781 template <G1Barrier barrier, bool do_mark_object>
4782 template <class T>
4783 void G1ParCopyClosure<barrier, do_mark_object>
4784 ::do_oop_work(T* p) {
4785   oop obj = oopDesc::load_decode_heap_oop(p);
4786 
4787   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4788 
4789   // here the null check is implicit in the cset_fast_test() test
4790   if (_g1->in_cset_fast_test(obj)) {
4791     oop forwardee;
4792     if (obj->is_forwarded()) {
4793       forwardee = obj->forwardee();
4794     } else {
4795       forwardee = copy_to_survivor_space(obj);
4796     }
4797     assert(forwardee != NULL, "forwardee should not be NULL");
4798     oopDesc::encode_store_heap_oop(p, forwardee);
4799     if (do_mark_object && forwardee != obj) {
4800       // If the object is self-forwarded we don't need to explicitly
4801       // mark it, the evacuation failure protocol will do so.
4802       mark_forwarded_object(obj, forwardee);
4803     }
4804 
4805     if (barrier == G1BarrierKlass) {
4806       do_klass_barrier(p, forwardee);
4807     }
4808   } else {
4809     // The object is not in collection set. If we're a root scanning
4810     // closure during an initial mark pause (i.e. do_mark_object will
4811     // be true) then attempt to mark the object.
4812     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4813       mark_object(obj);
4814     }
4815   }
4816 
4817   if (barrier == G1BarrierEvac && obj != NULL) {
4818     _par_scan_state->update_rs(_from, p, _worker_id);
4819   }
4820 }
4821 
4822 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4823 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4824 
4825 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4826   assert(has_partial_array_mask(p), "invariant");
4827   oop from_obj = clear_partial_array_mask(p);
4828 
4829   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4830   assert(from_obj->is_objArray(), "must be obj array");
4831   objArrayOop from_obj_array = objArrayOop(from_obj);
4832   // The from-space object contains the real length.
4833   int length                 = from_obj_array->length();
4834 
4835   assert(from_obj->is_forwarded(), "must be forwarded");
4836   oop to_obj                 = from_obj->forwardee();
4837   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4838   objArrayOop to_obj_array   = objArrayOop(to_obj);
4839   // We keep track of the next start index in the length field of the
4840   // to-space object.
4841   int next_index             = to_obj_array->length();
4842   assert(0 <= next_index && next_index < length,
4843          err_msg("invariant, next index: %d, length: %d", next_index, length));
4844 
4845   int start                  = next_index;
4846   int end                    = length;
4847   int remainder              = end - start;
4848   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4849   if (remainder > 2 * ParGCArrayScanChunk) {
4850     end = start + ParGCArrayScanChunk;
4851     to_obj_array->set_length(end);
4852     // Push the remainder before we process the range in case another
4853     // worker has run out of things to do and can steal it.
4854     oop* from_obj_p = set_partial_array_mask(from_obj);
4855     _par_scan_state->push_on_queue(from_obj_p);
4856   } else {
4857     assert(length == end, "sanity");
4858     // We'll process the final range for this object. Restore the length
4859     // so that the heap remains parsable in case of evacuation failure.
4860     to_obj_array->set_length(end);
4861   }
4862   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4863   // Process indexes [start,end). It will also process the header
4864   // along with the first chunk (i.e., the chunk with start == 0).
4865   // Note that at this point the length field of to_obj_array is not
4866   // correct given that we are using it to keep track of the next
4867   // start index. oop_iterate_range() (thankfully!) ignores the length
4868   // field and only relies on the start / end parameters.  It does
4869   // however return the size of the object which will be incorrect. So
4870   // we have to ignore it even if we wanted to use it.
4871   to_obj_array->oop_iterate_range(&_scanner, start, end);
4872 }
4873 
4874 class G1ParEvacuateFollowersClosure : public VoidClosure {
4875 protected:
4876   G1CollectedHeap*              _g1h;
4877   G1ParScanThreadState*         _par_scan_state;
4878   RefToScanQueueSet*            _queues;
4879   ParallelTaskTerminator*       _terminator;
4880 
4881   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4882   RefToScanQueueSet*      queues()         { return _queues; }
4883   ParallelTaskTerminator* terminator()     { return _terminator; }
4884 
4885 public:
4886   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4887                                 G1ParScanThreadState* par_scan_state,
4888                                 RefToScanQueueSet* queues,
4889                                 ParallelTaskTerminator* terminator)
4890     : _g1h(g1h), _par_scan_state(par_scan_state),
4891       _queues(queues), _terminator(terminator) {}
4892 
4893   void do_void();
4894 
4895 private:
4896   inline bool offer_termination();
4897 };
4898 
4899 bool G1ParEvacuateFollowersClosure::offer_termination() {
4900   G1ParScanThreadState* const pss = par_scan_state();
4901   pss->start_term_time();
4902   const bool res = terminator()->offer_termination();
4903   pss->end_term_time();
4904   return res;
4905 }
4906 
4907 void G1ParEvacuateFollowersClosure::do_void() {
4908   StarTask stolen_task;
4909   G1ParScanThreadState* const pss = par_scan_state();
4910   pss->trim_queue();
4911 
4912   do {
4913     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4914       assert(pss->verify_task(stolen_task), "sanity");
4915       if (stolen_task.is_narrow()) {
4916         pss->deal_with_reference((narrowOop*) stolen_task);
4917       } else {
4918         pss->deal_with_reference((oop*) stolen_task);
4919       }
4920 
4921       // We've just processed a reference and we might have made
4922       // available new entries on the queues. So we have to make sure
4923       // we drain the queues as necessary.
4924       pss->trim_queue();
4925     }
4926   } while (!offer_termination());
4927 
4928   pss->retire_alloc_buffers();
4929 }
4930 
4931 class G1KlassScanClosure : public KlassClosure {
4932  G1ParCopyHelper* _closure;
4933  bool             _process_only_dirty;
4934  int              _count;
4935  public:
4936   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4937       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4938   void do_klass(Klass* klass) {
4939     // If the klass has not been dirtied we know that there's
4940     // no references into  the young gen and we can skip it.
4941    if (!_process_only_dirty || klass->has_modified_oops()) {
4942       // Clean the klass since we're going to scavenge all the metadata.
4943       klass->clear_modified_oops();
4944 
4945       // Tell the closure that this klass is the Klass to scavenge
4946       // and is the one to dirty if oops are left pointing into the young gen.
4947       _closure->set_scanned_klass(klass);
4948 
4949       klass->oops_do(_closure);
4950 
4951       _closure->set_scanned_klass(NULL);
4952     }
4953     _count++;
4954   }
4955 };
4956 
4957 class G1ParTask : public AbstractGangTask {
4958 protected:
4959   G1CollectedHeap*       _g1h;
4960   RefToScanQueueSet      *_queues;
4961   ParallelTaskTerminator _terminator;
4962   uint _n_workers;
4963 
4964   Mutex _stats_lock;
4965   Mutex* stats_lock() { return &_stats_lock; }
4966 
4967   size_t getNCards() {
4968     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4969       / G1BlockOffsetSharedArray::N_bytes;
4970   }
4971 
4972 public:
4973   G1ParTask(G1CollectedHeap* g1h,
4974             RefToScanQueueSet *task_queues)
4975     : AbstractGangTask("G1 collection"),
4976       _g1h(g1h),
4977       _queues(task_queues),
4978       _terminator(0, _queues),
4979       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4980   {}
4981 
4982   RefToScanQueueSet* queues() { return _queues; }
4983 
4984   RefToScanQueue *work_queue(int i) {
4985     return queues()->queue(i);
4986   }
4987 
4988   ParallelTaskTerminator* terminator() { return &_terminator; }
4989 
4990   virtual void set_for_termination(int active_workers) {
4991     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4992     // in the young space (_par_seq_tasks) in the G1 heap
4993     // for SequentialSubTasksDone.
4994     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4995     // both of which need setting by set_n_termination().
4996     _g1h->SharedHeap::set_n_termination(active_workers);
4997     _g1h->set_n_termination(active_workers);
4998     terminator()->reset_for_reuse(active_workers);
4999     _n_workers = active_workers;
5000   }
5001 
5002   void work(uint worker_id) {
5003     if (worker_id >= _n_workers) return;  // no work needed this round
5004 
5005     double start_time_ms = os::elapsedTime() * 1000.0;
5006     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5007 
5008     {
5009       ResourceMark rm;
5010       HandleMark   hm;
5011 
5012       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
5013 
5014       G1ParScanThreadState            pss(_g1h, worker_id);
5015       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
5016       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5017       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
5018 
5019       pss.set_evac_closure(&scan_evac_cl);
5020       pss.set_evac_failure_closure(&evac_failure_cl);
5021       pss.set_partial_scan_closure(&partial_scan_cl);
5022 
5023       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
5024       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
5025 
5026       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5027       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5028 
5029       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
5030       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5031       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5032 
5033       OopClosure*                    scan_root_cl = &only_scan_root_cl;
5034       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
5035 
5036       if (_g1h->g1_policy()->during_initial_mark_pause()) {
5037         // We also need to mark copied objects.
5038         scan_root_cl = &scan_mark_root_cl;
5039         scan_klasses_cl = &scan_mark_klasses_cl_s;
5040       }
5041 
5042       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
5043 
5044       // Don't scan the scavengable methods in the code cache as part
5045       // of strong root scanning. The code roots that point into a
5046       // region in the collection set are scanned when we scan the
5047       // region's RSet.
5048       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5049 
5050       pss.start_strong_roots();
5051       _g1h->g1_process_strong_roots(/* is scavenging */ true,
5052                                     SharedHeap::ScanningOption(so),
5053                                     scan_root_cl,
5054                                     &push_heap_rs_cl,
5055                                     scan_klasses_cl,
5056                                     worker_id);
5057       pss.end_strong_roots();
5058 
5059       {
5060         double start = os::elapsedTime();
5061         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5062         evac.do_void();
5063         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5064         double term_ms = pss.term_time()*1000.0;
5065         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5066         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5067       }
5068       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5069       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5070 
5071       if (ParallelGCVerbose) {
5072         MutexLocker x(stats_lock());
5073         pss.print_termination_stats(worker_id);
5074       }
5075 
5076       assert(pss.refs()->is_empty(), "should be empty");
5077 
5078       // Close the inner scope so that the ResourceMark and HandleMark
5079       // destructors are executed here and are included as part of the
5080       // "GC Worker Time".
5081     }
5082 
5083     double end_time_ms = os::elapsedTime() * 1000.0;
5084     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5085   }
5086 };
5087 
5088 // *** Common G1 Evacuation Stuff
5089 
5090 // This method is run in a GC worker.
5091 
5092 void
5093 G1CollectedHeap::
5094 g1_process_strong_roots(bool is_scavenging,
5095                         ScanningOption so,
5096                         OopClosure* scan_non_heap_roots,
5097                         OopsInHeapRegionClosure* scan_rs,
5098                         G1KlassScanClosure* scan_klasses,
5099                         int worker_i) {
5100 
5101   // First scan the strong roots
5102   double ext_roots_start = os::elapsedTime();
5103   double closure_app_time_sec = 0.0;
5104 
5105   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5106 
5107   assert(so & SO_AllCodeCache || scan_rs != NULL, "must scan code roots somehow");
5108   // Walk the code cache/strong code roots w/o buffering, because StarTask
5109   // cannot handle unaligned oop locations.
5110   CodeBlobToOopClosure eager_scan_code_roots(&buf_scan_non_heap_roots, true /* do_marking */);
5111 
5112   process_strong_roots(false, // no scoping; this is parallel code
5113                        so,
5114                        &buf_scan_non_heap_roots,
5115                        &eager_scan_code_roots,
5116                        scan_klasses
5117                        );
5118 
5119   // Now the CM ref_processor roots.
5120   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5121     // We need to treat the discovered reference lists of the
5122     // concurrent mark ref processor as roots and keep entries
5123     // (which are added by the marking threads) on them live
5124     // until they can be processed at the end of marking.
5125     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5126   }
5127 
5128   // Finish up any enqueued closure apps (attributed as object copy time).
5129   buf_scan_non_heap_roots.done();
5130 
5131   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5132 
5133   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5134 
5135   double ext_root_time_ms =
5136     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5137 
5138   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5139 
5140   // During conc marking we have to filter the per-thread SATB buffers
5141   // to make sure we remove any oops into the CSet (which will show up
5142   // as implicitly live).
5143   double satb_filtering_ms = 0.0;
5144   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5145     if (mark_in_progress()) {
5146       double satb_filter_start = os::elapsedTime();
5147 
5148       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5149 
5150       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5151     }
5152   }
5153   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5154 
5155   // If this is an initial mark pause, and we're not scanning
5156   // the entire code cache, we need to mark the oops in the
5157   // strong code root lists for the regions that are not in
5158   // the collection set.
5159   // Note all threads participate in this set of root tasks.
5160   double mark_strong_code_roots_ms = 0.0;
5161   if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5162     double mark_strong_roots_start = os::elapsedTime();
5163     mark_strong_code_roots(worker_i);
5164     mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5165   }
5166   g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5167 
5168   // Now scan the complement of the collection set.
5169   if (scan_rs != NULL) {
5170     g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5171     buf_scan_non_heap_roots.done();
5172   }
5173   _process_strong_tasks->all_tasks_completed();
5174 }
5175 
5176 void
5177 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5178   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5179   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5180 }
5181 
5182 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5183 private:
5184   BoolObjectClosure* _is_alive;
5185   int _initial_string_table_size;
5186   int _initial_symbol_table_size;
5187 
5188   bool  _process_strings;
5189   int _strings_processed;
5190   int _strings_removed;
5191 
5192   bool  _process_symbols;
5193   int _symbols_processed;
5194   int _symbols_removed;
5195 public:
5196   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5197     AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5198     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5199     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5200 
5201     _initial_string_table_size = StringTable::the_table()->table_size();
5202     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5203     if (process_strings) {
5204       StringTable::clear_parallel_claimed_index();
5205     }
5206     if (process_symbols) {
5207       SymbolTable::clear_parallel_claimed_index();
5208     }
5209   }
5210 
5211   ~G1StringSymbolTableUnlinkTask() {
5212     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5213               err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5214                       StringTable::parallel_claimed_index(), _initial_string_table_size));
5215     guarantee(!_process_strings || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5216               err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5217                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5218   }
5219 
5220   void work(uint worker_id) {
5221     if (G1CollectedHeap::use_parallel_gc_threads()) {
5222       int strings_processed = 0;
5223       int strings_removed = 0;
5224       int symbols_processed = 0;
5225       int symbols_removed = 0;
5226       if (_process_strings) {
5227         StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5228         Atomic::add(strings_processed, &_strings_processed);
5229         Atomic::add(strings_removed, &_strings_removed);
5230       }
5231       if (_process_symbols) {
5232         SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5233         Atomic::add(symbols_processed, &_symbols_processed);
5234         Atomic::add(symbols_removed, &_symbols_removed);
5235       }
5236     } else {
5237       if (_process_strings) {
5238         StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5239       }
5240       if (_process_symbols) {
5241         SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5242       }
5243     }
5244   }
5245 
5246   size_t strings_processed() const { return (size_t)_strings_processed; }
5247   size_t strings_removed()   const { return (size_t)_strings_removed; }
5248 
5249   size_t symbols_processed() const { return (size_t)_symbols_processed; }
5250   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
5251 };
5252 
5253 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5254                                                      bool process_strings, bool process_symbols) {
5255   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5256                    _g1h->workers()->active_workers() : 1);
5257 
5258   G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5259   if (G1CollectedHeap::use_parallel_gc_threads()) {
5260     set_par_threads(n_workers);
5261     workers()->run_task(&g1_unlink_task);
5262     set_par_threads(0);
5263   } else {
5264     g1_unlink_task.work(0);
5265   }
5266   if (G1TraceStringSymbolTableScrubbing) {
5267     gclog_or_tty->print_cr("Cleaned string and symbol table, "
5268                            "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5269                            "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5270                            g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5271                            g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5272   }
5273 }
5274 
5275 // Weak Reference Processing support
5276 
5277 // An always "is_alive" closure that is used to preserve referents.
5278 // If the object is non-null then it's alive.  Used in the preservation
5279 // of referent objects that are pointed to by reference objects
5280 // discovered by the CM ref processor.
5281 class G1AlwaysAliveClosure: public BoolObjectClosure {
5282   G1CollectedHeap* _g1;
5283 public:
5284   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5285   bool do_object_b(oop p) {
5286     if (p != NULL) {
5287       return true;
5288     }
5289     return false;
5290   }
5291 };
5292 
5293 bool G1STWIsAliveClosure::do_object_b(oop p) {
5294   // An object is reachable if it is outside the collection set,
5295   // or is inside and copied.
5296   return !_g1->obj_in_cs(p) || p->is_forwarded();
5297 }
5298 
5299 // Non Copying Keep Alive closure
5300 class G1KeepAliveClosure: public OopClosure {
5301   G1CollectedHeap* _g1;
5302 public:
5303   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5304   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5305   void do_oop(      oop* p) {
5306     oop obj = *p;
5307 
5308     if (_g1->obj_in_cs(obj)) {
5309       assert( obj->is_forwarded(), "invariant" );
5310       *p = obj->forwardee();
5311     }
5312   }
5313 };
5314 
5315 // Copying Keep Alive closure - can be called from both
5316 // serial and parallel code as long as different worker
5317 // threads utilize different G1ParScanThreadState instances
5318 // and different queues.
5319 
5320 class G1CopyingKeepAliveClosure: public OopClosure {
5321   G1CollectedHeap*         _g1h;
5322   OopClosure*              _copy_non_heap_obj_cl;
5323   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5324   G1ParScanThreadState*    _par_scan_state;
5325 
5326 public:
5327   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5328                             OopClosure* non_heap_obj_cl,
5329                             OopsInHeapRegionClosure* metadata_obj_cl,
5330                             G1ParScanThreadState* pss):
5331     _g1h(g1h),
5332     _copy_non_heap_obj_cl(non_heap_obj_cl),
5333     _copy_metadata_obj_cl(metadata_obj_cl),
5334     _par_scan_state(pss)
5335   {}
5336 
5337   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5338   virtual void do_oop(      oop* p) { do_oop_work(p); }
5339 
5340   template <class T> void do_oop_work(T* p) {
5341     oop obj = oopDesc::load_decode_heap_oop(p);
5342 
5343     if (_g1h->obj_in_cs(obj)) {
5344       // If the referent object has been forwarded (either copied
5345       // to a new location or to itself in the event of an
5346       // evacuation failure) then we need to update the reference
5347       // field and, if both reference and referent are in the G1
5348       // heap, update the RSet for the referent.
5349       //
5350       // If the referent has not been forwarded then we have to keep
5351       // it alive by policy. Therefore we have copy the referent.
5352       //
5353       // If the reference field is in the G1 heap then we can push
5354       // on the PSS queue. When the queue is drained (after each
5355       // phase of reference processing) the object and it's followers
5356       // will be copied, the reference field set to point to the
5357       // new location, and the RSet updated. Otherwise we need to
5358       // use the the non-heap or metadata closures directly to copy
5359       // the referent object and update the pointer, while avoiding
5360       // updating the RSet.
5361 
5362       if (_g1h->is_in_g1_reserved(p)) {
5363         _par_scan_state->push_on_queue(p);
5364       } else {
5365         assert(!ClassLoaderDataGraph::contains((address)p),
5366                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5367                               PTR_FORMAT, p));
5368           _copy_non_heap_obj_cl->do_oop(p);
5369         }
5370       }
5371     }
5372 };
5373 
5374 // Serial drain queue closure. Called as the 'complete_gc'
5375 // closure for each discovered list in some of the
5376 // reference processing phases.
5377 
5378 class G1STWDrainQueueClosure: public VoidClosure {
5379 protected:
5380   G1CollectedHeap* _g1h;
5381   G1ParScanThreadState* _par_scan_state;
5382 
5383   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5384 
5385 public:
5386   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5387     _g1h(g1h),
5388     _par_scan_state(pss)
5389   { }
5390 
5391   void do_void() {
5392     G1ParScanThreadState* const pss = par_scan_state();
5393     pss->trim_queue();
5394   }
5395 };
5396 
5397 // Parallel Reference Processing closures
5398 
5399 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5400 // processing during G1 evacuation pauses.
5401 
5402 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5403 private:
5404   G1CollectedHeap*   _g1h;
5405   RefToScanQueueSet* _queues;
5406   FlexibleWorkGang*  _workers;
5407   int                _active_workers;
5408 
5409 public:
5410   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5411                         FlexibleWorkGang* workers,
5412                         RefToScanQueueSet *task_queues,
5413                         int n_workers) :
5414     _g1h(g1h),
5415     _queues(task_queues),
5416     _workers(workers),
5417     _active_workers(n_workers)
5418   {
5419     assert(n_workers > 0, "shouldn't call this otherwise");
5420   }
5421 
5422   // Executes the given task using concurrent marking worker threads.
5423   virtual void execute(ProcessTask& task);
5424   virtual void execute(EnqueueTask& task);
5425 };
5426 
5427 // Gang task for possibly parallel reference processing
5428 
5429 class G1STWRefProcTaskProxy: public AbstractGangTask {
5430   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5431   ProcessTask&     _proc_task;
5432   G1CollectedHeap* _g1h;
5433   RefToScanQueueSet *_task_queues;
5434   ParallelTaskTerminator* _terminator;
5435 
5436 public:
5437   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5438                      G1CollectedHeap* g1h,
5439                      RefToScanQueueSet *task_queues,
5440                      ParallelTaskTerminator* terminator) :
5441     AbstractGangTask("Process reference objects in parallel"),
5442     _proc_task(proc_task),
5443     _g1h(g1h),
5444     _task_queues(task_queues),
5445     _terminator(terminator)
5446   {}
5447 
5448   virtual void work(uint worker_id) {
5449     // The reference processing task executed by a single worker.
5450     ResourceMark rm;
5451     HandleMark   hm;
5452 
5453     G1STWIsAliveClosure is_alive(_g1h);
5454 
5455     G1ParScanThreadState pss(_g1h, worker_id);
5456 
5457     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5458     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5459     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5460 
5461     pss.set_evac_closure(&scan_evac_cl);
5462     pss.set_evac_failure_closure(&evac_failure_cl);
5463     pss.set_partial_scan_closure(&partial_scan_cl);
5464 
5465     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5466     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5467 
5468     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5469     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5470 
5471     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5472     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5473 
5474     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5475       // We also need to mark copied objects.
5476       copy_non_heap_cl = &copy_mark_non_heap_cl;
5477       copy_metadata_cl = &copy_mark_metadata_cl;
5478     }
5479 
5480     // Keep alive closure.
5481     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5482 
5483     // Complete GC closure
5484     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5485 
5486     // Call the reference processing task's work routine.
5487     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5488 
5489     // Note we cannot assert that the refs array is empty here as not all
5490     // of the processing tasks (specifically phase2 - pp2_work) execute
5491     // the complete_gc closure (which ordinarily would drain the queue) so
5492     // the queue may not be empty.
5493   }
5494 };
5495 
5496 // Driver routine for parallel reference processing.
5497 // Creates an instance of the ref processing gang
5498 // task and has the worker threads execute it.
5499 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5500   assert(_workers != NULL, "Need parallel worker threads.");
5501 
5502   ParallelTaskTerminator terminator(_active_workers, _queues);
5503   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5504 
5505   _g1h->set_par_threads(_active_workers);
5506   _workers->run_task(&proc_task_proxy);
5507   _g1h->set_par_threads(0);
5508 }
5509 
5510 // Gang task for parallel reference enqueueing.
5511 
5512 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5513   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5514   EnqueueTask& _enq_task;
5515 
5516 public:
5517   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5518     AbstractGangTask("Enqueue reference objects in parallel"),
5519     _enq_task(enq_task)
5520   { }
5521 
5522   virtual void work(uint worker_id) {
5523     _enq_task.work(worker_id);
5524   }
5525 };
5526 
5527 // Driver routine for parallel reference enqueueing.
5528 // Creates an instance of the ref enqueueing gang
5529 // task and has the worker threads execute it.
5530 
5531 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5532   assert(_workers != NULL, "Need parallel worker threads.");
5533 
5534   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5535 
5536   _g1h->set_par_threads(_active_workers);
5537   _workers->run_task(&enq_task_proxy);
5538   _g1h->set_par_threads(0);
5539 }
5540 
5541 // End of weak reference support closures
5542 
5543 // Abstract task used to preserve (i.e. copy) any referent objects
5544 // that are in the collection set and are pointed to by reference
5545 // objects discovered by the CM ref processor.
5546 
5547 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5548 protected:
5549   G1CollectedHeap* _g1h;
5550   RefToScanQueueSet      *_queues;
5551   ParallelTaskTerminator _terminator;
5552   uint _n_workers;
5553 
5554 public:
5555   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5556     AbstractGangTask("ParPreserveCMReferents"),
5557     _g1h(g1h),
5558     _queues(task_queues),
5559     _terminator(workers, _queues),
5560     _n_workers(workers)
5561   { }
5562 
5563   void work(uint worker_id) {
5564     ResourceMark rm;
5565     HandleMark   hm;
5566 
5567     G1ParScanThreadState            pss(_g1h, worker_id);
5568     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5569     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5570     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5571 
5572     pss.set_evac_closure(&scan_evac_cl);
5573     pss.set_evac_failure_closure(&evac_failure_cl);
5574     pss.set_partial_scan_closure(&partial_scan_cl);
5575 
5576     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5577 
5578 
5579     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5580     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5581 
5582     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5583     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5584 
5585     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5586     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5587 
5588     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5589       // We also need to mark copied objects.
5590       copy_non_heap_cl = &copy_mark_non_heap_cl;
5591       copy_metadata_cl = &copy_mark_metadata_cl;
5592     }
5593 
5594     // Is alive closure
5595     G1AlwaysAliveClosure always_alive(_g1h);
5596 
5597     // Copying keep alive closure. Applied to referent objects that need
5598     // to be copied.
5599     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5600 
5601     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5602 
5603     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5604     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5605 
5606     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5607     // So this must be true - but assert just in case someone decides to
5608     // change the worker ids.
5609     assert(0 <= worker_id && worker_id < limit, "sanity");
5610     assert(!rp->discovery_is_atomic(), "check this code");
5611 
5612     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5613     for (uint idx = worker_id; idx < limit; idx += stride) {
5614       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5615 
5616       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5617       while (iter.has_next()) {
5618         // Since discovery is not atomic for the CM ref processor, we
5619         // can see some null referent objects.
5620         iter.load_ptrs(DEBUG_ONLY(true));
5621         oop ref = iter.obj();
5622 
5623         // This will filter nulls.
5624         if (iter.is_referent_alive()) {
5625           iter.make_referent_alive();
5626         }
5627         iter.move_to_next();
5628       }
5629     }
5630 
5631     // Drain the queue - which may cause stealing
5632     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5633     drain_queue.do_void();
5634     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5635     assert(pss.refs()->is_empty(), "should be");
5636   }
5637 };
5638 
5639 // Weak Reference processing during an evacuation pause (part 1).
5640 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5641   double ref_proc_start = os::elapsedTime();
5642 
5643   ReferenceProcessor* rp = _ref_processor_stw;
5644   assert(rp->discovery_enabled(), "should have been enabled");
5645 
5646   // Any reference objects, in the collection set, that were 'discovered'
5647   // by the CM ref processor should have already been copied (either by
5648   // applying the external root copy closure to the discovered lists, or
5649   // by following an RSet entry).
5650   //
5651   // But some of the referents, that are in the collection set, that these
5652   // reference objects point to may not have been copied: the STW ref
5653   // processor would have seen that the reference object had already
5654   // been 'discovered' and would have skipped discovering the reference,
5655   // but would not have treated the reference object as a regular oop.
5656   // As a result the copy closure would not have been applied to the
5657   // referent object.
5658   //
5659   // We need to explicitly copy these referent objects - the references
5660   // will be processed at the end of remarking.
5661   //
5662   // We also need to do this copying before we process the reference
5663   // objects discovered by the STW ref processor in case one of these
5664   // referents points to another object which is also referenced by an
5665   // object discovered by the STW ref processor.
5666 
5667   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5668            no_of_gc_workers == workers()->active_workers(),
5669            "Need to reset active GC workers");
5670 
5671   set_par_threads(no_of_gc_workers);
5672   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5673                                                  no_of_gc_workers,
5674                                                  _task_queues);
5675 
5676   if (G1CollectedHeap::use_parallel_gc_threads()) {
5677     workers()->run_task(&keep_cm_referents);
5678   } else {
5679     keep_cm_referents.work(0);
5680   }
5681 
5682   set_par_threads(0);
5683 
5684   // Closure to test whether a referent is alive.
5685   G1STWIsAliveClosure is_alive(this);
5686 
5687   // Even when parallel reference processing is enabled, the processing
5688   // of JNI refs is serial and performed serially by the current thread
5689   // rather than by a worker. The following PSS will be used for processing
5690   // JNI refs.
5691 
5692   // Use only a single queue for this PSS.
5693   G1ParScanThreadState pss(this, 0);
5694 
5695   // We do not embed a reference processor in the copying/scanning
5696   // closures while we're actually processing the discovered
5697   // reference objects.
5698   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5699   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5700   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5701 
5702   pss.set_evac_closure(&scan_evac_cl);
5703   pss.set_evac_failure_closure(&evac_failure_cl);
5704   pss.set_partial_scan_closure(&partial_scan_cl);
5705 
5706   assert(pss.refs()->is_empty(), "pre-condition");
5707 
5708   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5709   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5710 
5711   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5712   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5713 
5714   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5715   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5716 
5717   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5718     // We also need to mark copied objects.
5719     copy_non_heap_cl = &copy_mark_non_heap_cl;
5720     copy_metadata_cl = &copy_mark_metadata_cl;
5721   }
5722 
5723   // Keep alive closure.
5724   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5725 
5726   // Serial Complete GC closure
5727   G1STWDrainQueueClosure drain_queue(this, &pss);
5728 
5729   // Setup the soft refs policy...
5730   rp->setup_policy(false);
5731 
5732   ReferenceProcessorStats stats;
5733   if (!rp->processing_is_mt()) {
5734     // Serial reference processing...
5735     stats = rp->process_discovered_references(&is_alive,
5736                                               &keep_alive,
5737                                               &drain_queue,
5738                                               NULL,
5739                                               _gc_timer_stw);
5740   } else {
5741     // Parallel reference processing
5742     assert(rp->num_q() == no_of_gc_workers, "sanity");
5743     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5744 
5745     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5746     stats = rp->process_discovered_references(&is_alive,
5747                                               &keep_alive,
5748                                               &drain_queue,
5749                                               &par_task_executor,
5750                                               _gc_timer_stw);
5751   }
5752 
5753   _gc_tracer_stw->report_gc_reference_stats(stats);
5754   // We have completed copying any necessary live referent objects
5755   // (that were not copied during the actual pause) so we can
5756   // retire any active alloc buffers
5757   pss.retire_alloc_buffers();
5758   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5759 
5760   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5761   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5762 }
5763 
5764 // Weak Reference processing during an evacuation pause (part 2).
5765 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5766   double ref_enq_start = os::elapsedTime();
5767 
5768   ReferenceProcessor* rp = _ref_processor_stw;
5769   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5770 
5771   // Now enqueue any remaining on the discovered lists on to
5772   // the pending list.
5773   if (!rp->processing_is_mt()) {
5774     // Serial reference processing...
5775     rp->enqueue_discovered_references();
5776   } else {
5777     // Parallel reference enqueueing
5778 
5779     assert(no_of_gc_workers == workers()->active_workers(),
5780            "Need to reset active workers");
5781     assert(rp->num_q() == no_of_gc_workers, "sanity");
5782     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5783 
5784     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5785     rp->enqueue_discovered_references(&par_task_executor);
5786   }
5787 
5788   rp->verify_no_references_recorded();
5789   assert(!rp->discovery_enabled(), "should have been disabled");
5790 
5791   // FIXME
5792   // CM's reference processing also cleans up the string and symbol tables.
5793   // Should we do that here also? We could, but it is a serial operation
5794   // and could significantly increase the pause time.
5795 
5796   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5797   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5798 }
5799 
5800 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5801   _expand_heap_after_alloc_failure = true;
5802   _evacuation_failed = false;
5803 
5804   // Should G1EvacuationFailureALot be in effect for this GC?
5805   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5806 
5807   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5808 
5809   // Disable the hot card cache.
5810   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5811   hot_card_cache->reset_hot_cache_claimed_index();
5812   hot_card_cache->set_use_cache(false);
5813 
5814   uint n_workers;
5815   if (G1CollectedHeap::use_parallel_gc_threads()) {
5816     n_workers =
5817       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5818                                      workers()->active_workers(),
5819                                      Threads::number_of_non_daemon_threads());
5820     assert(UseDynamicNumberOfGCThreads ||
5821            n_workers == workers()->total_workers(),
5822            "If not dynamic should be using all the  workers");
5823     workers()->set_active_workers(n_workers);
5824     set_par_threads(n_workers);
5825   } else {
5826     assert(n_par_threads() == 0,
5827            "Should be the original non-parallel value");
5828     n_workers = 1;
5829   }
5830 
5831   G1ParTask g1_par_task(this, _task_queues);
5832 
5833   init_for_evac_failure(NULL);
5834 
5835   rem_set()->prepare_for_younger_refs_iterate(true);
5836 
5837   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5838   double start_par_time_sec = os::elapsedTime();
5839   double end_par_time_sec;
5840 
5841   {
5842     StrongRootsScope srs(this);
5843 
5844     if (G1CollectedHeap::use_parallel_gc_threads()) {
5845       // The individual threads will set their evac-failure closures.
5846       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5847       // These tasks use ShareHeap::_process_strong_tasks
5848       assert(UseDynamicNumberOfGCThreads ||
5849              workers()->active_workers() == workers()->total_workers(),
5850              "If not dynamic should be using all the  workers");
5851       workers()->run_task(&g1_par_task);
5852     } else {
5853       g1_par_task.set_for_termination(n_workers);
5854       g1_par_task.work(0);
5855     }
5856     end_par_time_sec = os::elapsedTime();
5857 
5858     // Closing the inner scope will execute the destructor
5859     // for the StrongRootsScope object. We record the current
5860     // elapsed time before closing the scope so that time
5861     // taken for the SRS destructor is NOT included in the
5862     // reported parallel time.
5863   }
5864 
5865   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5866   g1_policy()->phase_times()->record_par_time(par_time_ms);
5867 
5868   double code_root_fixup_time_ms =
5869         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5870   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5871 
5872   set_par_threads(0);
5873 
5874   // Process any discovered reference objects - we have
5875   // to do this _before_ we retire the GC alloc regions
5876   // as we may have to copy some 'reachable' referent
5877   // objects (and their reachable sub-graphs) that were
5878   // not copied during the pause.
5879   process_discovered_references(n_workers);
5880 
5881   // Weak root processing.
5882   {
5883     G1STWIsAliveClosure is_alive(this);
5884     G1KeepAliveClosure keep_alive(this);
5885     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5886   }
5887 
5888   release_gc_alloc_regions(n_workers, evacuation_info);
5889   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5890 
5891   // Reset and re-enable the hot card cache.
5892   // Note the counts for the cards in the regions in the
5893   // collection set are reset when the collection set is freed.
5894   hot_card_cache->reset_hot_cache();
5895   hot_card_cache->set_use_cache(true);
5896 
5897   // Migrate the strong code roots attached to each region in
5898   // the collection set. Ideally we would like to do this
5899   // after we have finished the scanning/evacuation of the
5900   // strong code roots for a particular heap region.
5901   migrate_strong_code_roots();
5902 
5903   if (g1_policy()->during_initial_mark_pause()) {
5904     // Reset the claim values set during marking the strong code roots
5905     reset_heap_region_claim_values();
5906   }
5907 
5908   finalize_for_evac_failure();
5909 
5910   if (evacuation_failed()) {
5911     remove_self_forwarding_pointers();
5912 
5913     // Reset the G1EvacuationFailureALot counters and flags
5914     // Note: the values are reset only when an actual
5915     // evacuation failure occurs.
5916     NOT_PRODUCT(reset_evacuation_should_fail();)
5917   }
5918 
5919   // Enqueue any remaining references remaining on the STW
5920   // reference processor's discovered lists. We need to do
5921   // this after the card table is cleaned (and verified) as
5922   // the act of enqueueing entries on to the pending list
5923   // will log these updates (and dirty their associated
5924   // cards). We need these updates logged to update any
5925   // RSets.
5926   enqueue_discovered_references(n_workers);
5927 
5928   if (G1DeferredRSUpdate) {
5929     RedirtyLoggedCardTableEntryFastClosure redirty;
5930     dirty_card_queue_set().set_closure(&redirty);
5931     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5932 
5933     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5934     dcq.merge_bufferlists(&dirty_card_queue_set());
5935     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5936   }
5937   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5938 }
5939 
5940 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5941                                      size_t* pre_used,
5942                                      FreeRegionList* free_list,
5943                                      OldRegionSet* old_proxy_set,
5944                                      HumongousRegionSet* humongous_proxy_set,
5945                                      HRRSCleanupTask* hrrs_cleanup_task,
5946                                      bool par) {
5947   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5948     if (hr->isHumongous()) {
5949       assert(hr->startsHumongous(), "we should only see starts humongous");
5950       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5951     } else {
5952       _old_set.remove_with_proxy(hr, old_proxy_set);
5953       free_region(hr, pre_used, free_list, par);
5954     }
5955   } else {
5956     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5957   }
5958 }
5959 
5960 void G1CollectedHeap::free_region(HeapRegion* hr,
5961                                   size_t* pre_used,
5962                                   FreeRegionList* free_list,
5963                                   bool par) {
5964   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5965   assert(!hr->is_empty(), "the region should not be empty");
5966   assert(free_list != NULL, "pre-condition");
5967 
5968   // Clear the card counts for this region.
5969   // Note: we only need to do this if the region is not young
5970   // (since we don't refine cards in young regions).
5971   if (!hr->is_young()) {
5972     _cg1r->hot_card_cache()->reset_card_counts(hr);
5973   }
5974   *pre_used += hr->used();
5975   hr->hr_clear(par, true /* clear_space */);
5976   free_list->add_as_head(hr);
5977 }
5978 
5979 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5980                                      size_t* pre_used,
5981                                      FreeRegionList* free_list,
5982                                      HumongousRegionSet* humongous_proxy_set,
5983                                      bool par) {
5984   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5985   assert(free_list != NULL, "pre-condition");
5986   assert(humongous_proxy_set != NULL, "pre-condition");
5987 
5988   size_t hr_used = hr->used();
5989   size_t hr_capacity = hr->capacity();
5990   size_t hr_pre_used = 0;
5991   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5992   // We need to read this before we make the region non-humongous,
5993   // otherwise the information will be gone.
5994   uint last_index = hr->last_hc_index();
5995   hr->set_notHumongous();
5996   free_region(hr, &hr_pre_used, free_list, par);
5997 
5998   uint i = hr->hrs_index() + 1;
5999   while (i < last_index) {
6000     HeapRegion* curr_hr = region_at(i);
6001     assert(curr_hr->continuesHumongous(), "invariant");
6002     curr_hr->set_notHumongous();
6003     free_region(curr_hr, &hr_pre_used, free_list, par);
6004     i += 1;
6005   }
6006   assert(hr_pre_used == hr_used,
6007          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
6008                  "should be the same", hr_pre_used, hr_used));
6009   *pre_used += hr_pre_used;
6010 }
6011 
6012 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
6013                                        FreeRegionList* free_list,
6014                                        OldRegionSet* old_proxy_set,
6015                                        HumongousRegionSet* humongous_proxy_set,
6016                                        bool par) {
6017   if (pre_used > 0) {
6018     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
6019     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
6020     assert(_summary_bytes_used >= pre_used,
6021            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
6022                    "should be >= pre_used: "SIZE_FORMAT,
6023                    _summary_bytes_used, pre_used));
6024     _summary_bytes_used -= pre_used;
6025   }
6026   if (free_list != NULL && !free_list->is_empty()) {
6027     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6028     _free_list.add_as_head(free_list);
6029   }
6030   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
6031     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6032     _old_set.update_from_proxy(old_proxy_set);
6033   }
6034   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
6035     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6036     _humongous_set.update_from_proxy(humongous_proxy_set);
6037   }
6038 }
6039 
6040 class G1ParCleanupCTTask : public AbstractGangTask {
6041   G1SATBCardTableModRefBS* _ct_bs;
6042   G1CollectedHeap* _g1h;
6043   HeapRegion* volatile _su_head;
6044 public:
6045   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6046                      G1CollectedHeap* g1h) :
6047     AbstractGangTask("G1 Par Cleanup CT Task"),
6048     _ct_bs(ct_bs), _g1h(g1h) { }
6049 
6050   void work(uint worker_id) {
6051     HeapRegion* r;
6052     while (r = _g1h->pop_dirty_cards_region()) {
6053       clear_cards(r);
6054     }
6055   }
6056 
6057   void clear_cards(HeapRegion* r) {
6058     // Cards of the survivors should have already been dirtied.
6059     if (!r->is_survivor()) {
6060       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6061     }
6062   }
6063 };
6064 
6065 #ifndef PRODUCT
6066 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6067   G1CollectedHeap* _g1h;
6068   G1SATBCardTableModRefBS* _ct_bs;
6069 public:
6070   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6071     : _g1h(g1h), _ct_bs(ct_bs) { }
6072   virtual bool doHeapRegion(HeapRegion* r) {
6073     if (r->is_survivor()) {
6074       _g1h->verify_dirty_region(r);
6075     } else {
6076       _g1h->verify_not_dirty_region(r);
6077     }
6078     return false;
6079   }
6080 };
6081 
6082 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6083   // All of the region should be clean.
6084   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6085   MemRegion mr(hr->bottom(), hr->end());
6086   ct_bs->verify_not_dirty_region(mr);
6087 }
6088 
6089 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6090   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
6091   // dirty allocated blocks as they allocate them. The thread that
6092   // retires each region and replaces it with a new one will do a
6093   // maximal allocation to fill in [pre_dummy_top(),end()] but will
6094   // not dirty that area (one less thing to have to do while holding
6095   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6096   // is dirty.
6097   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6098   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6099   if (hr->is_young()) {
6100     ct_bs->verify_g1_young_region(mr);
6101   } else {
6102     ct_bs->verify_dirty_region(mr);
6103   }
6104 }
6105 
6106 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6107   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6108   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6109     verify_dirty_region(hr);
6110   }
6111 }
6112 
6113 void G1CollectedHeap::verify_dirty_young_regions() {
6114   verify_dirty_young_list(_young_list->first_region());
6115 }
6116 #endif
6117 
6118 void G1CollectedHeap::cleanUpCardTable() {
6119   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6120   double start = os::elapsedTime();
6121 
6122   {
6123     // Iterate over the dirty cards region list.
6124     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6125 
6126     if (G1CollectedHeap::use_parallel_gc_threads()) {
6127       set_par_threads();
6128       workers()->run_task(&cleanup_task);
6129       set_par_threads(0);
6130     } else {
6131       while (_dirty_cards_region_list) {
6132         HeapRegion* r = _dirty_cards_region_list;
6133         cleanup_task.clear_cards(r);
6134         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6135         if (_dirty_cards_region_list == r) {
6136           // The last region.
6137           _dirty_cards_region_list = NULL;
6138         }
6139         r->set_next_dirty_cards_region(NULL);
6140       }
6141     }
6142 #ifndef PRODUCT
6143     if (G1VerifyCTCleanup || VerifyAfterGC) {
6144       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6145       heap_region_iterate(&cleanup_verifier);
6146     }
6147 #endif
6148   }
6149 
6150   double elapsed = os::elapsedTime() - start;
6151   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6152 }
6153 
6154 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6155   size_t pre_used = 0;
6156   FreeRegionList local_free_list("Local List for CSet Freeing");
6157 
6158   double young_time_ms     = 0.0;
6159   double non_young_time_ms = 0.0;
6160 
6161   // Since the collection set is a superset of the the young list,
6162   // all we need to do to clear the young list is clear its
6163   // head and length, and unlink any young regions in the code below
6164   _young_list->clear();
6165 
6166   G1CollectorPolicy* policy = g1_policy();
6167 
6168   double start_sec = os::elapsedTime();
6169   bool non_young = true;
6170 
6171   HeapRegion* cur = cs_head;
6172   int age_bound = -1;
6173   size_t rs_lengths = 0;
6174 
6175   while (cur != NULL) {
6176     assert(!is_on_master_free_list(cur), "sanity");
6177     if (non_young) {
6178       if (cur->is_young()) {
6179         double end_sec = os::elapsedTime();
6180         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6181         non_young_time_ms += elapsed_ms;
6182 
6183         start_sec = os::elapsedTime();
6184         non_young = false;
6185       }
6186     } else {
6187       if (!cur->is_young()) {
6188         double end_sec = os::elapsedTime();
6189         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6190         young_time_ms += elapsed_ms;
6191 
6192         start_sec = os::elapsedTime();
6193         non_young = true;
6194       }
6195     }
6196 
6197     rs_lengths += cur->rem_set()->occupied();
6198 
6199     HeapRegion* next = cur->next_in_collection_set();
6200     assert(cur->in_collection_set(), "bad CS");
6201     cur->set_next_in_collection_set(NULL);
6202     cur->set_in_collection_set(false);
6203 
6204     if (cur->is_young()) {
6205       int index = cur->young_index_in_cset();
6206       assert(index != -1, "invariant");
6207       assert((uint) index < policy->young_cset_region_length(), "invariant");
6208       size_t words_survived = _surviving_young_words[index];
6209       cur->record_surv_words_in_group(words_survived);
6210 
6211       // At this point the we have 'popped' cur from the collection set
6212       // (linked via next_in_collection_set()) but it is still in the
6213       // young list (linked via next_young_region()). Clear the
6214       // _next_young_region field.
6215       cur->set_next_young_region(NULL);
6216     } else {
6217       int index = cur->young_index_in_cset();
6218       assert(index == -1, "invariant");
6219     }
6220 
6221     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6222             (!cur->is_young() && cur->young_index_in_cset() == -1),
6223             "invariant" );
6224 
6225     if (!cur->evacuation_failed()) {
6226       MemRegion used_mr = cur->used_region();
6227 
6228       // And the region is empty.
6229       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6230       free_region(cur, &pre_used, &local_free_list, false /* par */);
6231     } else {
6232       cur->uninstall_surv_rate_group();
6233       if (cur->is_young()) {
6234         cur->set_young_index_in_cset(-1);
6235       }
6236       cur->set_not_young();
6237       cur->set_evacuation_failed(false);
6238       // The region is now considered to be old.
6239       _old_set.add(cur);
6240       evacuation_info.increment_collectionset_used_after(cur->used());
6241     }
6242     cur = next;
6243   }
6244 
6245   evacuation_info.set_regions_freed(local_free_list.length());
6246   policy->record_max_rs_lengths(rs_lengths);
6247   policy->cset_regions_freed();
6248 
6249   double end_sec = os::elapsedTime();
6250   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6251 
6252   if (non_young) {
6253     non_young_time_ms += elapsed_ms;
6254   } else {
6255     young_time_ms += elapsed_ms;
6256   }
6257 
6258   update_sets_after_freeing_regions(pre_used, &local_free_list,
6259                                     NULL /* old_proxy_set */,
6260                                     NULL /* humongous_proxy_set */,
6261                                     false /* par */);
6262   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6263   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6264 }
6265 
6266 // This routine is similar to the above but does not record
6267 // any policy statistics or update free lists; we are abandoning
6268 // the current incremental collection set in preparation of a
6269 // full collection. After the full GC we will start to build up
6270 // the incremental collection set again.
6271 // This is only called when we're doing a full collection
6272 // and is immediately followed by the tearing down of the young list.
6273 
6274 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6275   HeapRegion* cur = cs_head;
6276 
6277   while (cur != NULL) {
6278     HeapRegion* next = cur->next_in_collection_set();
6279     assert(cur->in_collection_set(), "bad CS");
6280     cur->set_next_in_collection_set(NULL);
6281     cur->set_in_collection_set(false);
6282     cur->set_young_index_in_cset(-1);
6283     cur = next;
6284   }
6285 }
6286 
6287 void G1CollectedHeap::set_free_regions_coming() {
6288   if (G1ConcRegionFreeingVerbose) {
6289     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6290                            "setting free regions coming");
6291   }
6292 
6293   assert(!free_regions_coming(), "pre-condition");
6294   _free_regions_coming = true;
6295 }
6296 
6297 void G1CollectedHeap::reset_free_regions_coming() {
6298   assert(free_regions_coming(), "pre-condition");
6299 
6300   {
6301     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6302     _free_regions_coming = false;
6303     SecondaryFreeList_lock->notify_all();
6304   }
6305 
6306   if (G1ConcRegionFreeingVerbose) {
6307     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6308                            "reset free regions coming");
6309   }
6310 }
6311 
6312 void G1CollectedHeap::wait_while_free_regions_coming() {
6313   // Most of the time we won't have to wait, so let's do a quick test
6314   // first before we take the lock.
6315   if (!free_regions_coming()) {
6316     return;
6317   }
6318 
6319   if (G1ConcRegionFreeingVerbose) {
6320     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6321                            "waiting for free regions");
6322   }
6323 
6324   {
6325     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6326     while (free_regions_coming()) {
6327       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6328     }
6329   }
6330 
6331   if (G1ConcRegionFreeingVerbose) {
6332     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6333                            "done waiting for free regions");
6334   }
6335 }
6336 
6337 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6338   assert(heap_lock_held_for_gc(),
6339               "the heap lock should already be held by or for this thread");
6340   _young_list->push_region(hr);
6341 }
6342 
6343 class NoYoungRegionsClosure: public HeapRegionClosure {
6344 private:
6345   bool _success;
6346 public:
6347   NoYoungRegionsClosure() : _success(true) { }
6348   bool doHeapRegion(HeapRegion* r) {
6349     if (r->is_young()) {
6350       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6351                              r->bottom(), r->end());
6352       _success = false;
6353     }
6354     return false;
6355   }
6356   bool success() { return _success; }
6357 };
6358 
6359 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6360   bool ret = _young_list->check_list_empty(check_sample);
6361 
6362   if (check_heap) {
6363     NoYoungRegionsClosure closure;
6364     heap_region_iterate(&closure);
6365     ret = ret && closure.success();
6366   }
6367 
6368   return ret;
6369 }
6370 
6371 class TearDownRegionSetsClosure : public HeapRegionClosure {
6372 private:
6373   OldRegionSet *_old_set;
6374 
6375 public:
6376   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6377 
6378   bool doHeapRegion(HeapRegion* r) {
6379     if (r->is_empty()) {
6380       // We ignore empty regions, we'll empty the free list afterwards
6381     } else if (r->is_young()) {
6382       // We ignore young regions, we'll empty the young list afterwards
6383     } else if (r->isHumongous()) {
6384       // We ignore humongous regions, we're not tearing down the
6385       // humongous region set
6386     } else {
6387       // The rest should be old
6388       _old_set->remove(r);
6389     }
6390     return false;
6391   }
6392 
6393   ~TearDownRegionSetsClosure() {
6394     assert(_old_set->is_empty(), "post-condition");
6395   }
6396 };
6397 
6398 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6399   assert_at_safepoint(true /* should_be_vm_thread */);
6400 
6401   if (!free_list_only) {
6402     TearDownRegionSetsClosure cl(&_old_set);
6403     heap_region_iterate(&cl);
6404 
6405     // Need to do this after the heap iteration to be able to
6406     // recognize the young regions and ignore them during the iteration.
6407     _young_list->empty_list();
6408   }
6409   _free_list.remove_all();
6410 }
6411 
6412 class RebuildRegionSetsClosure : public HeapRegionClosure {
6413 private:
6414   bool            _free_list_only;
6415   OldRegionSet*   _old_set;
6416   FreeRegionList* _free_list;
6417   size_t          _total_used;
6418 
6419 public:
6420   RebuildRegionSetsClosure(bool free_list_only,
6421                            OldRegionSet* old_set, FreeRegionList* free_list) :
6422     _free_list_only(free_list_only),
6423     _old_set(old_set), _free_list(free_list), _total_used(0) {
6424     assert(_free_list->is_empty(), "pre-condition");
6425     if (!free_list_only) {
6426       assert(_old_set->is_empty(), "pre-condition");
6427     }
6428   }
6429 
6430   bool doHeapRegion(HeapRegion* r) {
6431     if (r->continuesHumongous()) {
6432       return false;
6433     }
6434 
6435     if (r->is_empty()) {
6436       // Add free regions to the free list
6437       _free_list->add_as_tail(r);
6438     } else if (!_free_list_only) {
6439       assert(!r->is_young(), "we should not come across young regions");
6440 
6441       if (r->isHumongous()) {
6442         // We ignore humongous regions, we left the humongous set unchanged
6443       } else {
6444         // The rest should be old, add them to the old set
6445         _old_set->add(r);
6446       }
6447       _total_used += r->used();
6448     }
6449 
6450     return false;
6451   }
6452 
6453   size_t total_used() {
6454     return _total_used;
6455   }
6456 };
6457 
6458 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6459   assert_at_safepoint(true /* should_be_vm_thread */);
6460 
6461   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6462   heap_region_iterate(&cl);
6463 
6464   if (!free_list_only) {
6465     _summary_bytes_used = cl.total_used();
6466   }
6467   assert(_summary_bytes_used == recalculate_used(),
6468          err_msg("inconsistent _summary_bytes_used, "
6469                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6470                  _summary_bytes_used, recalculate_used()));
6471 }
6472 
6473 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6474   _refine_cte_cl->set_concurrent(concurrent);
6475 }
6476 
6477 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6478   HeapRegion* hr = heap_region_containing(p);
6479   if (hr == NULL) {
6480     return false;
6481   } else {
6482     return hr->is_in(p);
6483   }
6484 }
6485 
6486 // Methods for the mutator alloc region
6487 
6488 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6489                                                       bool force) {
6490   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6491   assert(!force || g1_policy()->can_expand_young_list(),
6492          "if force is true we should be able to expand the young list");
6493   bool young_list_full = g1_policy()->is_young_list_full();
6494   if (force || !young_list_full) {
6495     HeapRegion* new_alloc_region = new_region(word_size,
6496                                               false /* do_expand */);
6497     if (new_alloc_region != NULL) {
6498       set_region_short_lived_locked(new_alloc_region);
6499       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6500       return new_alloc_region;
6501     }
6502   }
6503   return NULL;
6504 }
6505 
6506 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6507                                                   size_t allocated_bytes) {
6508   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6509   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6510 
6511   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6512   _summary_bytes_used += allocated_bytes;
6513   _hr_printer.retire(alloc_region);
6514   // We update the eden sizes here, when the region is retired,
6515   // instead of when it's allocated, since this is the point that its
6516   // used space has been recored in _summary_bytes_used.
6517   g1mm()->update_eden_size();
6518 }
6519 
6520 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6521                                                     bool force) {
6522   return _g1h->new_mutator_alloc_region(word_size, force);
6523 }
6524 
6525 void G1CollectedHeap::set_par_threads() {
6526   // Don't change the number of workers.  Use the value previously set
6527   // in the workgroup.
6528   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6529   uint n_workers = workers()->active_workers();
6530   assert(UseDynamicNumberOfGCThreads ||
6531            n_workers == workers()->total_workers(),
6532       "Otherwise should be using the total number of workers");
6533   if (n_workers == 0) {
6534     assert(false, "Should have been set in prior evacuation pause.");
6535     n_workers = ParallelGCThreads;
6536     workers()->set_active_workers(n_workers);
6537   }
6538   set_par_threads(n_workers);
6539 }
6540 
6541 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6542                                        size_t allocated_bytes) {
6543   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6544 }
6545 
6546 // Methods for the GC alloc regions
6547 
6548 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6549                                                  uint count,
6550                                                  GCAllocPurpose ap) {
6551   assert(FreeList_lock->owned_by_self(), "pre-condition");
6552 
6553   if (count < g1_policy()->max_regions(ap)) {
6554     HeapRegion* new_alloc_region = new_region(word_size,
6555                                               true /* do_expand */);
6556     if (new_alloc_region != NULL) {
6557       // We really only need to do this for old regions given that we
6558       // should never scan survivors. But it doesn't hurt to do it
6559       // for survivors too.
6560       new_alloc_region->set_saved_mark();
6561       if (ap == GCAllocForSurvived) {
6562         new_alloc_region->set_survivor();
6563         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6564       } else {
6565         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6566       }
6567       bool during_im = g1_policy()->during_initial_mark_pause();
6568       new_alloc_region->note_start_of_copying(during_im);
6569       return new_alloc_region;
6570     } else {
6571       g1_policy()->note_alloc_region_limit_reached(ap);
6572     }
6573   }
6574   return NULL;
6575 }
6576 
6577 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6578                                              size_t allocated_bytes,
6579                                              GCAllocPurpose ap) {
6580   bool during_im = g1_policy()->during_initial_mark_pause();
6581   alloc_region->note_end_of_copying(during_im);
6582   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6583   if (ap == GCAllocForSurvived) {
6584     young_list()->add_survivor_region(alloc_region);
6585   } else {
6586     _old_set.add(alloc_region);
6587   }
6588   _hr_printer.retire(alloc_region);
6589 }
6590 
6591 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6592                                                        bool force) {
6593   assert(!force, "not supported for GC alloc regions");
6594   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6595 }
6596 
6597 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6598                                           size_t allocated_bytes) {
6599   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6600                                GCAllocForSurvived);
6601 }
6602 
6603 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6604                                                   bool force) {
6605   assert(!force, "not supported for GC alloc regions");
6606   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6607 }
6608 
6609 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6610                                      size_t allocated_bytes) {
6611   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6612                                GCAllocForTenured);
6613 }
6614 // Heap region set verification
6615 
6616 class VerifyRegionListsClosure : public HeapRegionClosure {
6617 private:
6618   FreeRegionList*     _free_list;
6619   OldRegionSet*       _old_set;
6620   HumongousRegionSet* _humongous_set;
6621   uint                _region_count;
6622 
6623 public:
6624   VerifyRegionListsClosure(OldRegionSet* old_set,
6625                            HumongousRegionSet* humongous_set,
6626                            FreeRegionList* free_list) :
6627     _old_set(old_set), _humongous_set(humongous_set),
6628     _free_list(free_list), _region_count(0) { }
6629 
6630   uint region_count() { return _region_count; }
6631 
6632   bool doHeapRegion(HeapRegion* hr) {
6633     _region_count += 1;
6634 
6635     if (hr->continuesHumongous()) {
6636       return false;
6637     }
6638 
6639     if (hr->is_young()) {
6640       // TODO
6641     } else if (hr->startsHumongous()) {
6642       _humongous_set->verify_next_region(hr);
6643     } else if (hr->is_empty()) {
6644       _free_list->verify_next_region(hr);
6645     } else {
6646       _old_set->verify_next_region(hr);
6647     }
6648     return false;
6649   }
6650 };
6651 
6652 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6653                                              HeapWord* bottom) {
6654   HeapWord* end = bottom + HeapRegion::GrainWords;
6655   MemRegion mr(bottom, end);
6656   assert(_g1_reserved.contains(mr), "invariant");
6657   // This might return NULL if the allocation fails
6658   return new HeapRegion(hrs_index, _bot_shared, mr);
6659 }
6660 
6661 void G1CollectedHeap::verify_region_sets() {
6662   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6663 
6664   // First, check the explicit lists.
6665   _free_list.verify();
6666   {
6667     // Given that a concurrent operation might be adding regions to
6668     // the secondary free list we have to take the lock before
6669     // verifying it.
6670     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6671     _secondary_free_list.verify();
6672   }
6673   _old_set.verify();
6674   _humongous_set.verify();
6675 
6676   // If a concurrent region freeing operation is in progress it will
6677   // be difficult to correctly attributed any free regions we come
6678   // across to the correct free list given that they might belong to
6679   // one of several (free_list, secondary_free_list, any local lists,
6680   // etc.). So, if that's the case we will skip the rest of the
6681   // verification operation. Alternatively, waiting for the concurrent
6682   // operation to complete will have a non-trivial effect on the GC's
6683   // operation (no concurrent operation will last longer than the
6684   // interval between two calls to verification) and it might hide
6685   // any issues that we would like to catch during testing.
6686   if (free_regions_coming()) {
6687     return;
6688   }
6689 
6690   // Make sure we append the secondary_free_list on the free_list so
6691   // that all free regions we will come across can be safely
6692   // attributed to the free_list.
6693   append_secondary_free_list_if_not_empty_with_lock();
6694 
6695   // Finally, make sure that the region accounting in the lists is
6696   // consistent with what we see in the heap.
6697   _old_set.verify_start();
6698   _humongous_set.verify_start();
6699   _free_list.verify_start();
6700 
6701   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6702   heap_region_iterate(&cl);
6703 
6704   _old_set.verify_end();
6705   _humongous_set.verify_end();
6706   _free_list.verify_end();
6707 }
6708 
6709 // Optimized nmethod scanning
6710 
6711 class RegisterNMethodOopClosure: public OopClosure {
6712   G1CollectedHeap* _g1h;
6713   nmethod* _nm;
6714 
6715   template <class T> void do_oop_work(T* p) {
6716     T heap_oop = oopDesc::load_heap_oop(p);
6717     if (!oopDesc::is_null(heap_oop)) {
6718       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6719       HeapRegion* hr = _g1h->heap_region_containing(obj);
6720       assert(!hr->continuesHumongous(),
6721              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6722                      " starting at "HR_FORMAT,
6723                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6724 
6725       // HeapRegion::add_strong_code_root() avoids adding duplicate
6726       // entries but having duplicates is  OK since we "mark" nmethods
6727       // as visited when we scan the strong code root lists during the GC.
6728       hr->add_strong_code_root(_nm);
6729       assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6730              err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6731                      _nm, HR_FORMAT_PARAMS(hr)));
6732     }
6733   }
6734 
6735 public:
6736   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6737     _g1h(g1h), _nm(nm) {}
6738 
6739   void do_oop(oop* p)       { do_oop_work(p); }
6740   void do_oop(narrowOop* p) { do_oop_work(p); }
6741 };
6742 
6743 class UnregisterNMethodOopClosure: public OopClosure {
6744   G1CollectedHeap* _g1h;
6745   nmethod* _nm;
6746 
6747   template <class T> void do_oop_work(T* p) {
6748     T heap_oop = oopDesc::load_heap_oop(p);
6749     if (!oopDesc::is_null(heap_oop)) {
6750       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6751       HeapRegion* hr = _g1h->heap_region_containing(obj);
6752       assert(!hr->continuesHumongous(),
6753              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6754                      " starting at "HR_FORMAT,
6755                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6756 
6757       hr->remove_strong_code_root(_nm);
6758       assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6759              err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6760                      _nm, HR_FORMAT_PARAMS(hr)));
6761     }
6762   }
6763 
6764 public:
6765   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6766     _g1h(g1h), _nm(nm) {}
6767 
6768   void do_oop(oop* p)       { do_oop_work(p); }
6769   void do_oop(narrowOop* p) { do_oop_work(p); }
6770 };
6771 
6772 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6773   CollectedHeap::register_nmethod(nm);
6774 
6775   guarantee(nm != NULL, "sanity");
6776   RegisterNMethodOopClosure reg_cl(this, nm);
6777   nm->oops_do(&reg_cl);
6778 }
6779 
6780 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6781   CollectedHeap::unregister_nmethod(nm);
6782 
6783   guarantee(nm != NULL, "sanity");
6784   UnregisterNMethodOopClosure reg_cl(this, nm);
6785   nm->oops_do(&reg_cl, true);
6786 }
6787 
6788 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6789 public:
6790   bool doHeapRegion(HeapRegion *hr) {
6791     assert(!hr->isHumongous(),
6792            err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6793                    HR_FORMAT_PARAMS(hr)));
6794     hr->migrate_strong_code_roots();
6795     return false;
6796   }
6797 };
6798 
6799 void G1CollectedHeap::migrate_strong_code_roots() {
6800   MigrateCodeRootsHeapRegionClosure cl;
6801   double migrate_start = os::elapsedTime();
6802   collection_set_iterate(&cl);
6803   double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6804   g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6805 }
6806 
6807 // Mark all the code roots that point into regions *not* in the
6808 // collection set.
6809 //
6810 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6811 // walking the the code roots lists of regions not in the collection
6812 // set. Suppose we have an nmethod (M) that points to objects in two
6813 // separate regions - one in the collection set (R1) and one not (R2).
6814 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6815 // nmethod M when walking the code roots for R1. When we come to scan
6816 // the code roots for R2, we would see that M is already marked and it
6817 // would be skipped and the objects in R2 that are referenced from M
6818 // would not be evacuated.
6819 
6820 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6821 
6822   class MarkStrongCodeRootOopClosure: public OopClosure {
6823     ConcurrentMark* _cm;
6824     HeapRegion* _hr;
6825     uint _worker_id;
6826 
6827     template <class T> void do_oop_work(T* p) {
6828       T heap_oop = oopDesc::load_heap_oop(p);
6829       if (!oopDesc::is_null(heap_oop)) {
6830         oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6831         // Only mark objects in the region (which is assumed
6832         // to be not in the collection set).
6833         if (_hr->is_in(obj)) {
6834           _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6835         }
6836       }
6837     }
6838 
6839   public:
6840     MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6841       _cm(cm), _hr(hr), _worker_id(worker_id) {
6842       assert(!_hr->in_collection_set(), "sanity");
6843     }
6844 
6845     void do_oop(narrowOop* p) { do_oop_work(p); }
6846     void do_oop(oop* p)       { do_oop_work(p); }
6847   };
6848 
6849   MarkStrongCodeRootOopClosure _oop_cl;
6850 
6851 public:
6852   MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6853     _oop_cl(cm, hr, worker_id) {}
6854 
6855   void do_code_blob(CodeBlob* cb) {
6856     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6857     if (nm != NULL) {
6858       nm->oops_do(&_oop_cl);
6859     }
6860   }
6861 };
6862 
6863 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6864   G1CollectedHeap* _g1h;
6865   uint _worker_id;
6866 
6867 public:
6868   MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6869     _g1h(g1h), _worker_id(worker_id) {}
6870 
6871   bool doHeapRegion(HeapRegion *hr) {
6872     HeapRegionRemSet* hrrs = hr->rem_set();
6873     if (hr->continuesHumongous()) {
6874       // Code roots should never be attached to a continuation of a humongous region
6875       assert(hrrs->strong_code_roots_list_length() == 0,
6876              err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6877                      " starting at "HR_FORMAT", but has "INT32_FORMAT,
6878                      HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6879                      hrrs->strong_code_roots_list_length()));
6880       return false;
6881     }
6882 
6883     if (hr->in_collection_set()) {
6884       // Don't mark code roots into regions in the collection set here.
6885       // They will be marked when we scan them.
6886       return false;
6887     }
6888 
6889     MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6890     hr->strong_code_roots_do(&cb_cl);
6891     return false;
6892   }
6893 };
6894 
6895 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6896   MarkStrongCodeRootsHRClosure cl(this, worker_id);
6897   if (G1CollectedHeap::use_parallel_gc_threads()) {
6898     heap_region_par_iterate_chunked(&cl,
6899                                     worker_id,
6900                                     workers()->active_workers(),
6901                                     HeapRegion::ParMarkRootClaimValue);
6902   } else {
6903     heap_region_iterate(&cl);
6904   }
6905 }
6906 
6907 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6908   G1CollectedHeap* _g1h;
6909 
6910 public:
6911   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6912     _g1h(g1h) {}
6913 
6914   void do_code_blob(CodeBlob* cb) {
6915     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6916     if (nm == NULL) {
6917       return;
6918     }
6919 
6920     if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6921       _g1h->register_nmethod(nm);
6922     }
6923   }
6924 };
6925 
6926 void G1CollectedHeap::rebuild_strong_code_roots() {
6927   RebuildStrongCodeRootClosure blob_cl(this);
6928   CodeCache::blobs_do(&blob_cl);
6929 }