1 /*
   2  * Copyright (c) 2001, 2011, 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/icBuffer.hpp"
  27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  34 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  35 #include "gc_implementation/g1/g1MarkSweep.hpp"
  36 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  37 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  38 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  39 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  40 #include "gc_implementation/g1/vm_operations_g1.hpp"
  41 #include "gc_implementation/shared/isGCActiveMark.hpp"
  42 #include "memory/gcLocker.inline.hpp"
  43 #include "memory/genOopClosures.inline.hpp"
  44 #include "memory/generationSpec.hpp"
  45 #include "memory/referenceProcessor.hpp"
  46 #include "oops/oop.inline.hpp"
  47 #include "oops/oop.pcgc.inline.hpp"
  48 #include "runtime/aprofiler.hpp"
  49 #include "runtime/vmThread.hpp"
  50 
  51 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  52 
  53 // turn it on so that the contents of the young list (scan-only /
  54 // to-be-collected) are printed at "strategic" points before / during
  55 // / after the collection --- this is useful for debugging
  56 #define YOUNG_LIST_VERBOSE 0
  57 // CURRENT STATUS
  58 // This file is under construction.  Search for "FIXME".
  59 
  60 // INVARIANTS/NOTES
  61 //
  62 // All allocation activity covered by the G1CollectedHeap interface is
  63 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  64 // and allocate_new_tlab, which are the "entry" points to the
  65 // allocation code from the rest of the JVM.  (Note that this does not
  66 // apply to TLAB allocation, which is not part of this interface: it
  67 // is done by clients of this interface.)
  68 
  69 // Notes on implementation of parallelism in different tasks.
  70 //
  71 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  72 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  73 // It does use run_task() which sets _n_workers in the task.
  74 // G1ParTask executes g1_process_strong_roots() ->
  75 // SharedHeap::process_strong_roots() which calls eventuall to
  76 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  77 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  78 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  79 //
  80 
  81 // Local to this file.
  82 
  83 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  84   SuspendibleThreadSet* _sts;
  85   G1RemSet* _g1rs;
  86   ConcurrentG1Refine* _cg1r;
  87   bool _concurrent;
  88 public:
  89   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  90                               G1RemSet* g1rs,
  91                               ConcurrentG1Refine* cg1r) :
  92     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
  93   {}
  94   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
  95     bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
  96     // This path is executed by the concurrent refine or mutator threads,
  97     // concurrently, and so we do not care if card_ptr contains references
  98     // that point into the collection set.
  99     assert(!oops_into_cset, "should be");
 100 
 101     if (_concurrent && _sts->should_yield()) {
 102       // Caller will actually yield.
 103       return false;
 104     }
 105     // Otherwise, we finished successfully; return true.
 106     return true;
 107   }
 108   void set_concurrent(bool b) { _concurrent = b; }
 109 };
 110 
 111 
 112 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 113   int _calls;
 114   G1CollectedHeap* _g1h;
 115   CardTableModRefBS* _ctbs;
 116   int _histo[256];
 117 public:
 118   ClearLoggedCardTableEntryClosure() :
 119     _calls(0)
 120   {
 121     _g1h = G1CollectedHeap::heap();
 122     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 123     for (int i = 0; i < 256; i++) _histo[i] = 0;
 124   }
 125   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 126     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 127       _calls++;
 128       unsigned char* ujb = (unsigned char*)card_ptr;
 129       int ind = (int)(*ujb);
 130       _histo[ind]++;
 131       *card_ptr = -1;
 132     }
 133     return true;
 134   }
 135   int calls() { return _calls; }
 136   void print_histo() {
 137     gclog_or_tty->print_cr("Card table value histogram:");
 138     for (int i = 0; i < 256; i++) {
 139       if (_histo[i] != 0) {
 140         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 141       }
 142     }
 143   }
 144 };
 145 
 146 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 147   int _calls;
 148   G1CollectedHeap* _g1h;
 149   CardTableModRefBS* _ctbs;
 150 public:
 151   RedirtyLoggedCardTableEntryClosure() :
 152     _calls(0)
 153   {
 154     _g1h = G1CollectedHeap::heap();
 155     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 156   }
 157   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 158     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 159       _calls++;
 160       *card_ptr = 0;
 161     }
 162     return true;
 163   }
 164   int calls() { return _calls; }
 165 };
 166 
 167 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 168 public:
 169   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 170     *card_ptr = CardTableModRefBS::dirty_card_val();
 171     return true;
 172   }
 173 };
 174 
 175 YoungList::YoungList(G1CollectedHeap* g1h)
 176   : _g1h(g1h), _head(NULL),
 177     _length(0),
 178     _last_sampled_rs_lengths(0),
 179     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
 180 {
 181   guarantee( check_list_empty(false), "just making sure..." );
 182 }
 183 
 184 void YoungList::push_region(HeapRegion *hr) {
 185   assert(!hr->is_young(), "should not already be young");
 186   assert(hr->get_next_young_region() == NULL, "cause it should!");
 187 
 188   hr->set_next_young_region(_head);
 189   _head = hr;
 190 
 191   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 192   ++_length;
 193 }
 194 
 195 void YoungList::add_survivor_region(HeapRegion* hr) {
 196   assert(hr->is_survivor(), "should be flagged as survivor region");
 197   assert(hr->get_next_young_region() == NULL, "cause it should!");
 198 
 199   hr->set_next_young_region(_survivor_head);
 200   if (_survivor_head == NULL) {
 201     _survivor_tail = hr;
 202   }
 203   _survivor_head = hr;
 204   ++_survivor_length;
 205 }
 206 
 207 void YoungList::empty_list(HeapRegion* list) {
 208   while (list != NULL) {
 209     HeapRegion* next = list->get_next_young_region();
 210     list->set_next_young_region(NULL);
 211     list->uninstall_surv_rate_group();
 212     list->set_not_young();
 213     list = next;
 214   }
 215 }
 216 
 217 void YoungList::empty_list() {
 218   assert(check_list_well_formed(), "young list should be well formed");
 219 
 220   empty_list(_head);
 221   _head = NULL;
 222   _length = 0;
 223 
 224   empty_list(_survivor_head);
 225   _survivor_head = NULL;
 226   _survivor_tail = NULL;
 227   _survivor_length = 0;
 228 
 229   _last_sampled_rs_lengths = 0;
 230 
 231   assert(check_list_empty(false), "just making sure...");
 232 }
 233 
 234 bool YoungList::check_list_well_formed() {
 235   bool ret = true;
 236 
 237   size_t length = 0;
 238   HeapRegion* curr = _head;
 239   HeapRegion* last = NULL;
 240   while (curr != NULL) {
 241     if (!curr->is_young()) {
 242       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 243                              "incorrectly tagged (y: %d, surv: %d)",
 244                              curr->bottom(), curr->end(),
 245                              curr->is_young(), curr->is_survivor());
 246       ret = false;
 247     }
 248     ++length;
 249     last = curr;
 250     curr = curr->get_next_young_region();
 251   }
 252   ret = ret && (length == _length);
 253 
 254   if (!ret) {
 255     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 256     gclog_or_tty->print_cr("###   list has %d entries, _length is %d",
 257                            length, _length);
 258   }
 259 
 260   return ret;
 261 }
 262 
 263 bool YoungList::check_list_empty(bool check_sample) {
 264   bool ret = true;
 265 
 266   if (_length != 0) {
 267     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
 268                   _length);
 269     ret = false;
 270   }
 271   if (check_sample && _last_sampled_rs_lengths != 0) {
 272     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 273     ret = false;
 274   }
 275   if (_head != NULL) {
 276     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 277     ret = false;
 278   }
 279   if (!ret) {
 280     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 281   }
 282 
 283   return ret;
 284 }
 285 
 286 void
 287 YoungList::rs_length_sampling_init() {
 288   _sampled_rs_lengths = 0;
 289   _curr               = _head;
 290 }
 291 
 292 bool
 293 YoungList::rs_length_sampling_more() {
 294   return _curr != NULL;
 295 }
 296 
 297 void
 298 YoungList::rs_length_sampling_next() {
 299   assert( _curr != NULL, "invariant" );
 300   size_t rs_length = _curr->rem_set()->occupied();
 301 
 302   _sampled_rs_lengths += rs_length;
 303 
 304   // The current region may not yet have been added to the
 305   // incremental collection set (it gets added when it is
 306   // retired as the current allocation region).
 307   if (_curr->in_collection_set()) {
 308     // Update the collection set policy information for this region
 309     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 310   }
 311 
 312   _curr = _curr->get_next_young_region();
 313   if (_curr == NULL) {
 314     _last_sampled_rs_lengths = _sampled_rs_lengths;
 315     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 316   }
 317 }
 318 
 319 void
 320 YoungList::reset_auxilary_lists() {
 321   guarantee( is_empty(), "young list should be empty" );
 322   assert(check_list_well_formed(), "young list should be well formed");
 323 
 324   // Add survivor regions to SurvRateGroup.
 325   _g1h->g1_policy()->note_start_adding_survivor_regions();
 326   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 327 
 328   int young_index_in_cset = 0;
 329   for (HeapRegion* curr = _survivor_head;
 330        curr != NULL;
 331        curr = curr->get_next_young_region()) {
 332     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 333 
 334     // The region is a non-empty survivor so let's add it to
 335     // the incremental collection set for the next evacuation
 336     // pause.
 337     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 338     young_index_in_cset += 1;
 339   }
 340   assert((size_t) young_index_in_cset == _survivor_length,
 341          "post-condition");
 342   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 343 
 344   _head   = _survivor_head;
 345   _length = _survivor_length;
 346   if (_survivor_head != NULL) {
 347     assert(_survivor_tail != NULL, "cause it shouldn't be");
 348     assert(_survivor_length > 0, "invariant");
 349     _survivor_tail->set_next_young_region(NULL);
 350   }
 351 
 352   // Don't clear the survivor list handles until the start of
 353   // the next evacuation pause - we need it in order to re-tag
 354   // the survivor regions from this evacuation pause as 'young'
 355   // at the start of the next.
 356 
 357   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 358 
 359   assert(check_list_well_formed(), "young list should be well formed");
 360 }
 361 
 362 void YoungList::print() {
 363   HeapRegion* lists[] = {_head,   _survivor_head};
 364   const char* names[] = {"YOUNG", "SURVIVOR"};
 365 
 366   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 367     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 368     HeapRegion *curr = lists[list];
 369     if (curr == NULL)
 370       gclog_or_tty->print_cr("  empty");
 371     while (curr != NULL) {
 372       gclog_or_tty->print_cr("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
 373                              "age: %4d, y: %d, surv: %d",
 374                              curr->bottom(), curr->end(),
 375                              curr->top(),
 376                              curr->prev_top_at_mark_start(),
 377                              curr->next_top_at_mark_start(),
 378                              curr->top_at_conc_mark_count(),
 379                              curr->age_in_surv_rate_group_cond(),
 380                              curr->is_young(),
 381                              curr->is_survivor());
 382       curr = curr->get_next_young_region();
 383     }
 384   }
 385 
 386   gclog_or_tty->print_cr("");
 387 }
 388 
 389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 390 {
 391   // Claim the right to put the region on the dirty cards region list
 392   // by installing a self pointer.
 393   HeapRegion* next = hr->get_next_dirty_cards_region();
 394   if (next == NULL) {
 395     HeapRegion* res = (HeapRegion*)
 396       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 397                           NULL);
 398     if (res == NULL) {
 399       HeapRegion* head;
 400       do {
 401         // Put the region to the dirty cards region list.
 402         head = _dirty_cards_region_list;
 403         next = (HeapRegion*)
 404           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 405         if (next == head) {
 406           assert(hr->get_next_dirty_cards_region() == hr,
 407                  "hr->get_next_dirty_cards_region() != hr");
 408           if (next == NULL) {
 409             // The last region in the list points to itself.
 410             hr->set_next_dirty_cards_region(hr);
 411           } else {
 412             hr->set_next_dirty_cards_region(next);
 413           }
 414         }
 415       } while (next != head);
 416     }
 417   }
 418 }
 419 
 420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 421 {
 422   HeapRegion* head;
 423   HeapRegion* hr;
 424   do {
 425     head = _dirty_cards_region_list;
 426     if (head == NULL) {
 427       return NULL;
 428     }
 429     HeapRegion* new_head = head->get_next_dirty_cards_region();
 430     if (head == new_head) {
 431       // The last region.
 432       new_head = NULL;
 433     }
 434     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 435                                           head);
 436   } while (hr != head);
 437   assert(hr != NULL, "invariant");
 438   hr->set_next_dirty_cards_region(NULL);
 439   return hr;
 440 }
 441 
 442 void G1CollectedHeap::stop_conc_gc_threads() {
 443   _cg1r->stop();
 444   _cmThread->stop();
 445 }
 446 
 447 #ifdef ASSERT
 448 // A region is added to the collection set as it is retired
 449 // so an address p can point to a region which will be in the
 450 // collection set but has not yet been retired.  This method
 451 // therefore is only accurate during a GC pause after all
 452 // regions have been retired.  It is used for debugging
 453 // to check if an nmethod has references to objects that can
 454 // be move during a partial collection.  Though it can be
 455 // inaccurate, it is sufficient for G1 because the conservative
 456 // implementation of is_scavengable() for G1 will indicate that
 457 // all nmethods must be scanned during a partial collection.
 458 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 459   HeapRegion* hr = heap_region_containing(p);
 460   return hr != NULL && hr->in_collection_set();
 461 }
 462 #endif
 463 
 464 // Returns true if the reference points to an object that
 465 // can move in an incremental collecction.
 466 bool G1CollectedHeap::is_scavengable(const void* p) {
 467   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 468   G1CollectorPolicy* g1p = g1h->g1_policy();
 469   HeapRegion* hr = heap_region_containing(p);
 470   if (hr == NULL) {
 471      // perm gen (or null)
 472      return false;
 473   } else {
 474     return !hr->isHumongous();
 475   }
 476 }
 477 
 478 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 479   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 480   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
 481 
 482   // Count the dirty cards at the start.
 483   CountNonCleanMemRegionClosure count1(this);
 484   ct_bs->mod_card_iterate(&count1);
 485   int orig_count = count1.n();
 486 
 487   // First clear the logged cards.
 488   ClearLoggedCardTableEntryClosure clear;
 489   dcqs.set_closure(&clear);
 490   dcqs.apply_closure_to_all_completed_buffers();
 491   dcqs.iterate_closure_all_threads(false);
 492   clear.print_histo();
 493 
 494   // Now ensure that there's no dirty cards.
 495   CountNonCleanMemRegionClosure count2(this);
 496   ct_bs->mod_card_iterate(&count2);
 497   if (count2.n() != 0) {
 498     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 499                            count2.n(), orig_count);
 500   }
 501   guarantee(count2.n() == 0, "Card table should be clean.");
 502 
 503   RedirtyLoggedCardTableEntryClosure redirty;
 504   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 505   dcqs.apply_closure_to_all_completed_buffers();
 506   dcqs.iterate_closure_all_threads(false);
 507   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 508                          clear.calls(), orig_count);
 509   guarantee(redirty.calls() == clear.calls(),
 510             "Or else mechanism is broken.");
 511 
 512   CountNonCleanMemRegionClosure count3(this);
 513   ct_bs->mod_card_iterate(&count3);
 514   if (count3.n() != orig_count) {
 515     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 516                            orig_count, count3.n());
 517     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 518   }
 519 
 520   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 521 }
 522 
 523 // Private class members.
 524 
 525 G1CollectedHeap* G1CollectedHeap::_g1h;
 526 
 527 // Private methods.
 528 
 529 HeapRegion*
 530 G1CollectedHeap::new_region_try_secondary_free_list() {
 531   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 532   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 533     if (!_secondary_free_list.is_empty()) {
 534       if (G1ConcRegionFreeingVerbose) {
 535         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 536                                "secondary_free_list has "SIZE_FORMAT" entries",
 537                                _secondary_free_list.length());
 538       }
 539       // It looks as if there are free regions available on the
 540       // secondary_free_list. Let's move them to the free_list and try
 541       // again to allocate from it.
 542       append_secondary_free_list();
 543 
 544       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 545              "empty we should have moved at least one entry to the free_list");
 546       HeapRegion* res = _free_list.remove_head();
 547       if (G1ConcRegionFreeingVerbose) {
 548         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 549                                "allocated "HR_FORMAT" from secondary_free_list",
 550                                HR_FORMAT_PARAMS(res));
 551       }
 552       return res;
 553     }
 554 
 555     // Wait here until we get notifed either when (a) there are no
 556     // more free regions coming or (b) some regions have been moved on
 557     // the secondary_free_list.
 558     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 559   }
 560 
 561   if (G1ConcRegionFreeingVerbose) {
 562     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 563                            "could not allocate from secondary_free_list");
 564   }
 565   return NULL;
 566 }
 567 
 568 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 569   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 570          "the only time we use this to allocate a humongous region is "
 571          "when we are allocating a single humongous region");
 572 
 573   HeapRegion* res;
 574   if (G1StressConcRegionFreeing) {
 575     if (!_secondary_free_list.is_empty()) {
 576       if (G1ConcRegionFreeingVerbose) {
 577         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 578                                "forced to look at the secondary_free_list");
 579       }
 580       res = new_region_try_secondary_free_list();
 581       if (res != NULL) {
 582         return res;
 583       }
 584     }
 585   }
 586   res = _free_list.remove_head_or_null();
 587   if (res == NULL) {
 588     if (G1ConcRegionFreeingVerbose) {
 589       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 590                              "res == NULL, trying the secondary_free_list");
 591     }
 592     res = new_region_try_secondary_free_list();
 593   }
 594   if (res == NULL && do_expand) {
 595     ergo_verbose1(ErgoHeapSizing,
 596                   "attempt heap expansion",
 597                   ergo_format_reason("region allocation request failed")
 598                   ergo_format_byte("allocation request"),
 599                   word_size * HeapWordSize);
 600     if (expand(word_size * HeapWordSize)) {
 601       // Even though the heap was expanded, it might not have reached
 602       // the desired size. So, we cannot assume that the allocation
 603       // will succeed.
 604       res = _free_list.remove_head_or_null();
 605     }
 606   }
 607   return res;
 608 }
 609 
 610 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
 611                                                           size_t word_size) {
 612   assert(isHumongous(word_size), "word_size should be humongous");
 613   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 614 
 615   size_t first = G1_NULL_HRS_INDEX;
 616   if (num_regions == 1) {
 617     // Only one region to allocate, no need to go through the slower
 618     // path. The caller will attempt the expasion if this fails, so
 619     // let's not try to expand here too.
 620     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 621     if (hr != NULL) {
 622       first = hr->hrs_index();
 623     } else {
 624       first = G1_NULL_HRS_INDEX;
 625     }
 626   } else {
 627     // We can't allocate humongous regions while cleanupComplete() is
 628     // running, since some of the regions we find to be empty might not
 629     // yet be added to the free list and it is not straightforward to
 630     // know which list they are on so that we can remove them. Note
 631     // that we only need to do this if we need to allocate more than
 632     // one region to satisfy the current humongous allocation
 633     // request. If we are only allocating one region we use the common
 634     // region allocation code (see above).
 635     wait_while_free_regions_coming();
 636     append_secondary_free_list_if_not_empty_with_lock();
 637 
 638     if (free_regions() >= num_regions) {
 639       first = _hrs.find_contiguous(num_regions);
 640       if (first != G1_NULL_HRS_INDEX) {
 641         for (size_t i = first; i < first + num_regions; ++i) {
 642           HeapRegion* hr = region_at(i);
 643           assert(hr->is_empty(), "sanity");
 644           assert(is_on_master_free_list(hr), "sanity");
 645           hr->set_pending_removal(true);
 646         }
 647         _free_list.remove_all_pending(num_regions);
 648       }
 649     }
 650   }
 651   return first;
 652 }
 653 
 654 HeapWord*
 655 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first,
 656                                                            size_t num_regions,
 657                                                            size_t word_size) {
 658   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 659   assert(isHumongous(word_size), "word_size should be humongous");
 660   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 661 
 662   // Index of last region in the series + 1.
 663   size_t last = first + num_regions;
 664 
 665   // We need to initialize the region(s) we just discovered. This is
 666   // a bit tricky given that it can happen concurrently with
 667   // refinement threads refining cards on these regions and
 668   // potentially wanting to refine the BOT as they are scanning
 669   // those cards (this can happen shortly after a cleanup; see CR
 670   // 6991377). So we have to set up the region(s) carefully and in
 671   // a specific order.
 672 
 673   // The word size sum of all the regions we will allocate.
 674   size_t word_size_sum = num_regions * HeapRegion::GrainWords;
 675   assert(word_size <= word_size_sum, "sanity");
 676 
 677   // This will be the "starts humongous" region.
 678   HeapRegion* first_hr = region_at(first);
 679   // The header of the new object will be placed at the bottom of
 680   // the first region.
 681   HeapWord* new_obj = first_hr->bottom();
 682   // This will be the new end of the first region in the series that
 683   // should also match the end of the last region in the seriers.
 684   HeapWord* new_end = new_obj + word_size_sum;
 685   // This will be the new top of the first region that will reflect
 686   // this allocation.
 687   HeapWord* new_top = new_obj + word_size;
 688 
 689   // First, we need to zero the header of the space that we will be
 690   // allocating. When we update top further down, some refinement
 691   // threads might try to scan the region. By zeroing the header we
 692   // ensure that any thread that will try to scan the region will
 693   // come across the zero klass word and bail out.
 694   //
 695   // NOTE: It would not have been correct to have used
 696   // CollectedHeap::fill_with_object() and make the space look like
 697   // an int array. The thread that is doing the allocation will
 698   // later update the object header to a potentially different array
 699   // type and, for a very short period of time, the klass and length
 700   // fields will be inconsistent. This could cause a refinement
 701   // thread to calculate the object size incorrectly.
 702   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 703 
 704   // We will set up the first region as "starts humongous". This
 705   // will also update the BOT covering all the regions to reflect
 706   // that there is a single object that starts at the bottom of the
 707   // first region.
 708   first_hr->set_startsHumongous(new_top, new_end);
 709 
 710   // Then, if there are any, we will set up the "continues
 711   // humongous" regions.
 712   HeapRegion* hr = NULL;
 713   for (size_t i = first + 1; i < last; ++i) {
 714     hr = region_at(i);
 715     hr->set_continuesHumongous(first_hr);
 716   }
 717   // If we have "continues humongous" regions (hr != NULL), then the
 718   // end of the last one should match new_end.
 719   assert(hr == NULL || hr->end() == new_end, "sanity");
 720 
 721   // Up to this point no concurrent thread would have been able to
 722   // do any scanning on any region in this series. All the top
 723   // fields still point to bottom, so the intersection between
 724   // [bottom,top] and [card_start,card_end] will be empty. Before we
 725   // update the top fields, we'll do a storestore to make sure that
 726   // no thread sees the update to top before the zeroing of the
 727   // object header and the BOT initialization.
 728   OrderAccess::storestore();
 729 
 730   // Now that the BOT and the object header have been initialized,
 731   // we can update top of the "starts humongous" region.
 732   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 733          "new_top should be in this region");
 734   first_hr->set_top(new_top);
 735   if (_hr_printer.is_active()) {
 736     HeapWord* bottom = first_hr->bottom();
 737     HeapWord* end = first_hr->orig_end();
 738     if ((first + 1) == last) {
 739       // the series has a single humongous region
 740       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 741     } else {
 742       // the series has more than one humongous regions
 743       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 744     }
 745   }
 746 
 747   // Now, we will update the top fields of the "continues humongous"
 748   // regions. The reason we need to do this is that, otherwise,
 749   // these regions would look empty and this will confuse parts of
 750   // G1. For example, the code that looks for a consecutive number
 751   // of empty regions will consider them empty and try to
 752   // re-allocate them. We can extend is_empty() to also include
 753   // !continuesHumongous(), but it is easier to just update the top
 754   // fields here. The way we set top for all regions (i.e., top ==
 755   // end for all regions but the last one, top == new_top for the
 756   // last one) is actually used when we will free up the humongous
 757   // region in free_humongous_region().
 758   hr = NULL;
 759   for (size_t i = first + 1; i < last; ++i) {
 760     hr = region_at(i);
 761     if ((i + 1) == last) {
 762       // last continues humongous region
 763       assert(hr->bottom() < new_top && new_top <= hr->end(),
 764              "new_top should fall on this region");
 765       hr->set_top(new_top);
 766       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 767     } else {
 768       // not last one
 769       assert(new_top > hr->end(), "new_top should be above this region");
 770       hr->set_top(hr->end());
 771       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 772     }
 773   }
 774   // If we have continues humongous regions (hr != NULL), then the
 775   // end of the last one should match new_end and its top should
 776   // match new_top.
 777   assert(hr == NULL ||
 778          (hr->end() == new_end && hr->top() == new_top), "sanity");
 779 
 780   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 781   _summary_bytes_used += first_hr->used();
 782   _humongous_set.add(first_hr);
 783 
 784   return new_obj;
 785 }
 786 
 787 // If could fit into free regions w/o expansion, try.
 788 // Otherwise, if can expand, do so.
 789 // Otherwise, if using ex regions might help, try with ex given back.
 790 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 791   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 792 
 793   verify_region_sets_optional();
 794 
 795   size_t num_regions =
 796          round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 797   size_t x_size = expansion_regions();
 798   size_t fs = _hrs.free_suffix();
 799   size_t first = humongous_obj_allocate_find_first(num_regions, word_size);
 800   if (first == G1_NULL_HRS_INDEX) {
 801     // The only thing we can do now is attempt expansion.
 802     if (fs + x_size >= num_regions) {
 803       // If the number of regions we're trying to allocate for this
 804       // object is at most the number of regions in the free suffix,
 805       // then the call to humongous_obj_allocate_find_first() above
 806       // should have succeeded and we wouldn't be here.
 807       //
 808       // We should only be trying to expand when the free suffix is
 809       // not sufficient for the object _and_ we have some expansion
 810       // room available.
 811       assert(num_regions > fs, "earlier allocation should have succeeded");
 812 
 813       ergo_verbose1(ErgoHeapSizing,
 814                     "attempt heap expansion",
 815                     ergo_format_reason("humongous allocation request failed")
 816                     ergo_format_byte("allocation request"),
 817                     word_size * HeapWordSize);
 818       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 819         // Even though the heap was expanded, it might not have
 820         // reached the desired size. So, we cannot assume that the
 821         // allocation will succeed.
 822         first = humongous_obj_allocate_find_first(num_regions, word_size);
 823       }
 824     }
 825   }
 826 
 827   HeapWord* result = NULL;
 828   if (first != G1_NULL_HRS_INDEX) {
 829     result =
 830       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 831     assert(result != NULL, "it should always return a valid result");
 832 
 833     // A successful humongous object allocation changes the used space
 834     // information of the old generation so we need to recalculate the
 835     // sizes and update the jstat counters here.
 836     g1mm()->update_sizes();
 837   }
 838 
 839   verify_region_sets_optional();
 840 
 841   return result;
 842 }
 843 
 844 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 845   assert_heap_not_locked_and_not_at_safepoint();
 846   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 847 
 848   unsigned int dummy_gc_count_before;
 849   return attempt_allocation(word_size, &dummy_gc_count_before);
 850 }
 851 
 852 HeapWord*
 853 G1CollectedHeap::mem_allocate(size_t word_size,
 854                               bool*  gc_overhead_limit_was_exceeded) {
 855   assert_heap_not_locked_and_not_at_safepoint();
 856 
 857   // Loop until the allocation is satisified, or unsatisfied after GC.
 858   for (int try_count = 1; /* we'll return */; try_count += 1) {
 859     unsigned int gc_count_before;
 860 
 861     HeapWord* result = NULL;
 862     if (!isHumongous(word_size)) {
 863       result = attempt_allocation(word_size, &gc_count_before);
 864     } else {
 865       result = attempt_allocation_humongous(word_size, &gc_count_before);
 866     }
 867     if (result != NULL) {
 868       return result;
 869     }
 870 
 871     // Create the garbage collection operation...
 872     VM_G1CollectForAllocation op(gc_count_before, word_size);
 873     // ...and get the VM thread to execute it.
 874     VMThread::execute(&op);
 875 
 876     if (op.prologue_succeeded() && op.pause_succeeded()) {
 877       // If the operation was successful we'll return the result even
 878       // if it is NULL. If the allocation attempt failed immediately
 879       // after a Full GC, it's unlikely we'll be able to allocate now.
 880       HeapWord* result = op.result();
 881       if (result != NULL && !isHumongous(word_size)) {
 882         // Allocations that take place on VM operations do not do any
 883         // card dirtying and we have to do it here. We only have to do
 884         // this for non-humongous allocations, though.
 885         dirty_young_block(result, word_size);
 886       }
 887       return result;
 888     } else {
 889       assert(op.result() == NULL,
 890              "the result should be NULL if the VM op did not succeed");
 891     }
 892 
 893     // Give a warning if we seem to be looping forever.
 894     if ((QueuedAllocationWarningCount > 0) &&
 895         (try_count % QueuedAllocationWarningCount == 0)) {
 896       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 897     }
 898   }
 899 
 900   ShouldNotReachHere();
 901   return NULL;
 902 }
 903 
 904 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 905                                            unsigned int *gc_count_before_ret) {
 906   // Make sure you read the note in attempt_allocation_humongous().
 907 
 908   assert_heap_not_locked_and_not_at_safepoint();
 909   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 910          "be called for humongous allocation requests");
 911 
 912   // We should only get here after the first-level allocation attempt
 913   // (attempt_allocation()) failed to allocate.
 914 
 915   // We will loop until a) we manage to successfully perform the
 916   // allocation or b) we successfully schedule a collection which
 917   // fails to perform the allocation. b) is the only case when we'll
 918   // return NULL.
 919   HeapWord* result = NULL;
 920   for (int try_count = 1; /* we'll return */; try_count += 1) {
 921     bool should_try_gc;
 922     unsigned int gc_count_before;
 923 
 924     {
 925       MutexLockerEx x(Heap_lock);
 926 
 927       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 928                                                       false /* bot_updates */);
 929       if (result != NULL) {
 930         return result;
 931       }
 932 
 933       // If we reach here, attempt_allocation_locked() above failed to
 934       // allocate a new region. So the mutator alloc region should be NULL.
 935       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 936 
 937       if (GC_locker::is_active_and_needs_gc()) {
 938         if (g1_policy()->can_expand_young_list()) {
 939           // No need for an ergo verbose message here,
 940           // can_expand_young_list() does this when it returns true.
 941           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 942                                                       false /* bot_updates */);
 943           if (result != NULL) {
 944             return result;
 945           }
 946         }
 947         should_try_gc = false;
 948       } else {
 949         // Read the GC count while still holding the Heap_lock.
 950         gc_count_before = SharedHeap::heap()->total_collections();
 951         should_try_gc = true;
 952       }
 953     }
 954 
 955     if (should_try_gc) {
 956       bool succeeded;
 957       result = do_collection_pause(word_size, gc_count_before, &succeeded);
 958       if (result != NULL) {
 959         assert(succeeded, "only way to get back a non-NULL result");
 960         return result;
 961       }
 962 
 963       if (succeeded) {
 964         // If we get here we successfully scheduled a collection which
 965         // failed to allocate. No point in trying to allocate
 966         // further. We'll just return NULL.
 967         MutexLockerEx x(Heap_lock);
 968         *gc_count_before_ret = SharedHeap::heap()->total_collections();
 969         return NULL;
 970       }
 971     } else {
 972       GC_locker::stall_until_clear();
 973     }
 974 
 975     // We can reach here if we were unsuccessul in scheduling a
 976     // collection (because another thread beat us to it) or if we were
 977     // stalled due to the GC locker. In either can we should retry the
 978     // allocation attempt in case another thread successfully
 979     // performed a collection and reclaimed enough space. We do the
 980     // first attempt (without holding the Heap_lock) here and the
 981     // follow-on attempt will be at the start of the next loop
 982     // iteration (after taking the Heap_lock).
 983     result = _mutator_alloc_region.attempt_allocation(word_size,
 984                                                       false /* bot_updates */);
 985     if (result != NULL ){
 986       return result;
 987     }
 988 
 989     // Give a warning if we seem to be looping forever.
 990     if ((QueuedAllocationWarningCount > 0) &&
 991         (try_count % QueuedAllocationWarningCount == 0)) {
 992       warning("G1CollectedHeap::attempt_allocation_slow() "
 993               "retries %d times", try_count);
 994     }
 995   }
 996 
 997   ShouldNotReachHere();
 998   return NULL;
 999 }
1000 
1001 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1002                                           unsigned int * gc_count_before_ret) {
1003   // The structure of this method has a lot of similarities to
1004   // attempt_allocation_slow(). The reason these two were not merged
1005   // into a single one is that such a method would require several "if
1006   // allocation is not humongous do this, otherwise do that"
1007   // conditional paths which would obscure its flow. In fact, an early
1008   // version of this code did use a unified method which was harder to
1009   // follow and, as a result, it had subtle bugs that were hard to
1010   // track down. So keeping these two methods separate allows each to
1011   // be more readable. It will be good to keep these two in sync as
1012   // much as possible.
1013 
1014   assert_heap_not_locked_and_not_at_safepoint();
1015   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1016          "should only be called for humongous allocations");
1017 
1018   // We will loop until a) we manage to successfully perform the
1019   // allocation or b) we successfully schedule a collection which
1020   // fails to perform the allocation. b) is the only case when we'll
1021   // return NULL.
1022   HeapWord* result = NULL;
1023   for (int try_count = 1; /* we'll return */; try_count += 1) {
1024     bool should_try_gc;
1025     unsigned int gc_count_before;
1026 
1027     {
1028       MutexLockerEx x(Heap_lock);
1029 
1030       // Given that humongous objects are not allocated in young
1031       // regions, we'll first try to do the allocation without doing a
1032       // collection hoping that there's enough space in the heap.
1033       result = humongous_obj_allocate(word_size);
1034       if (result != NULL) {
1035         return result;
1036       }
1037 
1038       if (GC_locker::is_active_and_needs_gc()) {
1039         should_try_gc = false;
1040       } else {
1041         // Read the GC count while still holding the Heap_lock.
1042         gc_count_before = SharedHeap::heap()->total_collections();
1043         should_try_gc = true;
1044       }
1045     }
1046 
1047     if (should_try_gc) {
1048       // If we failed to allocate the humongous object, we should try to
1049       // do a collection pause (if we're allowed) in case it reclaims
1050       // enough space for the allocation to succeed after the pause.
1051 
1052       bool succeeded;
1053       result = do_collection_pause(word_size, gc_count_before, &succeeded);
1054       if (result != NULL) {
1055         assert(succeeded, "only way to get back a non-NULL result");
1056         return result;
1057       }
1058 
1059       if (succeeded) {
1060         // If we get here we successfully scheduled a collection which
1061         // failed to allocate. No point in trying to allocate
1062         // further. We'll just return NULL.
1063         MutexLockerEx x(Heap_lock);
1064         *gc_count_before_ret = SharedHeap::heap()->total_collections();
1065         return NULL;
1066       }
1067     } else {
1068       GC_locker::stall_until_clear();
1069     }
1070 
1071     // We can reach here if we were unsuccessul in scheduling a
1072     // collection (because another thread beat us to it) or if we were
1073     // stalled due to the GC locker. In either can we should retry the
1074     // allocation attempt in case another thread successfully
1075     // performed a collection and reclaimed enough space.  Give a
1076     // warning if we seem to be looping forever.
1077 
1078     if ((QueuedAllocationWarningCount > 0) &&
1079         (try_count % QueuedAllocationWarningCount == 0)) {
1080       warning("G1CollectedHeap::attempt_allocation_humongous() "
1081               "retries %d times", try_count);
1082     }
1083   }
1084 
1085   ShouldNotReachHere();
1086   return NULL;
1087 }
1088 
1089 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1090                                        bool expect_null_mutator_alloc_region) {
1091   assert_at_safepoint(true /* should_be_vm_thread */);
1092   assert(_mutator_alloc_region.get() == NULL ||
1093                                              !expect_null_mutator_alloc_region,
1094          "the current alloc region was unexpectedly found to be non-NULL");
1095 
1096   if (!isHumongous(word_size)) {
1097     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1098                                                       false /* bot_updates */);
1099   } else {
1100     return humongous_obj_allocate(word_size);
1101   }
1102 
1103   ShouldNotReachHere();
1104 }
1105 
1106 class PostMCRemSetClearClosure: public HeapRegionClosure {
1107   ModRefBarrierSet* _mr_bs;
1108 public:
1109   PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1110   bool doHeapRegion(HeapRegion* r) {
1111     r->reset_gc_time_stamp();
1112     if (r->continuesHumongous())
1113       return false;
1114     HeapRegionRemSet* hrrs = r->rem_set();
1115     if (hrrs != NULL) hrrs->clear();
1116     // You might think here that we could clear just the cards
1117     // corresponding to the used region.  But no: if we leave a dirty card
1118     // in a region we might allocate into, then it would prevent that card
1119     // from being enqueued, and cause it to be missed.
1120     // Re: the performance cost: we shouldn't be doing full GC anyway!
1121     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1122     return false;
1123   }
1124 };
1125 
1126 
1127 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1128   ModRefBarrierSet* _mr_bs;
1129 public:
1130   PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1131   bool doHeapRegion(HeapRegion* r) {
1132     if (r->continuesHumongous()) return false;
1133     if (r->used_region().word_size() != 0) {
1134       _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1135     }
1136     return false;
1137   }
1138 };
1139 
1140 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1141   G1CollectedHeap*   _g1h;
1142   UpdateRSOopClosure _cl;
1143   int                _worker_i;
1144 public:
1145   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1146     _cl(g1->g1_rem_set(), worker_i),
1147     _worker_i(worker_i),
1148     _g1h(g1)
1149   { }
1150 
1151   bool doHeapRegion(HeapRegion* r) {
1152     if (!r->continuesHumongous()) {
1153       _cl.set_from(r);
1154       r->oop_iterate(&_cl);
1155     }
1156     return false;
1157   }
1158 };
1159 
1160 class ParRebuildRSTask: public AbstractGangTask {
1161   G1CollectedHeap* _g1;
1162 public:
1163   ParRebuildRSTask(G1CollectedHeap* g1)
1164     : AbstractGangTask("ParRebuildRSTask"),
1165       _g1(g1)
1166   { }
1167 
1168   void work(int i) {
1169     RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1170     _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1171                                           _g1->workers()->active_workers(),
1172                                          HeapRegion::RebuildRSClaimValue);
1173   }
1174 };
1175 
1176 class PostCompactionPrinterClosure: public HeapRegionClosure {
1177 private:
1178   G1HRPrinter* _hr_printer;
1179 public:
1180   bool doHeapRegion(HeapRegion* hr) {
1181     assert(!hr->is_young(), "not expecting to find young regions");
1182     // We only generate output for non-empty regions.
1183     if (!hr->is_empty()) {
1184       if (!hr->isHumongous()) {
1185         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1186       } else if (hr->startsHumongous()) {
1187         if (hr->capacity() == HeapRegion::GrainBytes) {
1188           // single humongous region
1189           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1190         } else {
1191           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1192         }
1193       } else {
1194         assert(hr->continuesHumongous(), "only way to get here");
1195         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1196       }
1197     }
1198     return false;
1199   }
1200 
1201   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1202     : _hr_printer(hr_printer) { }
1203 };
1204 
1205 bool G1CollectedHeap::do_collection(bool explicit_gc,
1206                                     bool clear_all_soft_refs,
1207                                     size_t word_size) {
1208   assert_at_safepoint(true /* should_be_vm_thread */);
1209 
1210   if (GC_locker::check_active_before_gc()) {
1211     return false;
1212   }
1213 
1214   SvcGCMarker sgcm(SvcGCMarker::FULL);
1215   ResourceMark rm;
1216 
1217   if (PrintHeapAtGC) {
1218     Universe::print_heap_before_gc();
1219   }
1220 
1221   HRSPhaseSetter x(HRSPhaseFullGC);
1222   verify_region_sets_optional();
1223 
1224   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1225                            collector_policy()->should_clear_all_soft_refs();
1226 
1227   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1228 
1229   {
1230     IsGCActiveMark x;
1231 
1232     // Timing
1233     bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1234     assert(!system_gc || explicit_gc, "invariant");
1235     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1236     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1237     TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1238                 PrintGC, true, gclog_or_tty);
1239 
1240     TraceCollectorStats tcs(g1mm()->full_collection_counters());
1241     TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1242 
1243     double start = os::elapsedTime();
1244     g1_policy()->record_full_collection_start();
1245 
1246     wait_while_free_regions_coming();
1247     append_secondary_free_list_if_not_empty_with_lock();
1248 
1249     gc_prologue(true);
1250     increment_total_collections(true /* full gc */);
1251 
1252     size_t g1h_prev_used = used();
1253     assert(used() == recalculate_used(), "Should be equal");
1254 
1255     if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1256       HandleMark hm;  // Discard invalid handles created during verification
1257       gclog_or_tty->print(" VerifyBeforeGC:");
1258       prepare_for_verify();
1259       Universe::verify(/* allow dirty */ true,
1260                        /* silent      */ false,
1261                        /* option      */ VerifyOption_G1UsePrevMarking);
1262 
1263     }
1264     pre_full_gc_dump();
1265 
1266     COMPILER2_PRESENT(DerivedPointerTable::clear());
1267 
1268     // Disable discovery and empty the discovered lists
1269     // for the CM ref processor.
1270     ref_processor_cm()->disable_discovery();
1271     ref_processor_cm()->abandon_partial_discovery();
1272     ref_processor_cm()->verify_no_references_recorded();
1273 
1274     // Abandon current iterations of concurrent marking and concurrent
1275     // refinement, if any are in progress.
1276     concurrent_mark()->abort();
1277 
1278     // Make sure we'll choose a new allocation region afterwards.
1279     release_mutator_alloc_region();
1280     abandon_gc_alloc_regions();
1281     g1_rem_set()->cleanupHRRS();
1282 
1283     // We should call this after we retire any currently active alloc
1284     // regions so that all the ALLOC / RETIRE events are generated
1285     // before the start GC event.
1286     _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1287 
1288     // We may have added regions to the current incremental collection
1289     // set between the last GC or pause and now. We need to clear the
1290     // incremental collection set and then start rebuilding it afresh
1291     // after this full GC.
1292     abandon_collection_set(g1_policy()->inc_cset_head());
1293     g1_policy()->clear_incremental_cset();
1294     g1_policy()->stop_incremental_cset_building();
1295 
1296     tear_down_region_sets(false /* free_list_only */);
1297     g1_policy()->set_full_young_gcs(true);
1298 
1299     // See the comments in g1CollectedHeap.hpp and
1300     // G1CollectedHeap::ref_processing_init() about
1301     // how reference processing currently works in G1.
1302 
1303     // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1304     ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1305 
1306     // Temporarily clear the STW ref processor's _is_alive_non_header field.
1307     ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1308 
1309     ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1310     ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1311 
1312     // Do collection work
1313     {
1314       HandleMark hm;  // Discard invalid handles created during gc
1315       G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1316     }
1317 
1318     assert(free_regions() == 0, "we should not have added any free regions");
1319     rebuild_region_sets(false /* free_list_only */);
1320 
1321     // Enqueue any discovered reference objects that have
1322     // not been removed from the discovered lists.
1323     ref_processor_stw()->enqueue_discovered_references();
1324 
1325     COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1326 
1327     MemoryService::track_memory_usage();
1328 
1329     if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1330       HandleMark hm;  // Discard invalid handles created during verification
1331       gclog_or_tty->print(" VerifyAfterGC:");
1332       prepare_for_verify();
1333       Universe::verify(/* allow dirty */ false,
1334                        /* silent      */ false,
1335                        /* option      */ VerifyOption_G1UsePrevMarking);
1336 
1337     }
1338 
1339     assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1340     ref_processor_stw()->verify_no_references_recorded();
1341 
1342     // Note: since we've just done a full GC, concurrent
1343     // marking is no longer active. Therefore we need not
1344     // re-enable reference discovery for the CM ref processor.
1345     // That will be done at the start of the next marking cycle.
1346     assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1347     ref_processor_cm()->verify_no_references_recorded();
1348 
1349     reset_gc_time_stamp();
1350     // Since everything potentially moved, we will clear all remembered
1351     // sets, and clear all cards.  Later we will rebuild remebered
1352     // sets. We will also reset the GC time stamps of the regions.
1353     PostMCRemSetClearClosure rs_clear(mr_bs());
1354     heap_region_iterate(&rs_clear);
1355 
1356     // Resize the heap if necessary.
1357     resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1358 
1359     if (_hr_printer.is_active()) {
1360       // We should do this after we potentially resize the heap so
1361       // that all the COMMIT / UNCOMMIT events are generated before
1362       // the end GC event.
1363 
1364       PostCompactionPrinterClosure cl(hr_printer());
1365       heap_region_iterate(&cl);
1366 
1367       _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1368     }
1369 
1370     if (_cg1r->use_cache()) {
1371       _cg1r->clear_and_record_card_counts();
1372       _cg1r->clear_hot_cache();
1373     }
1374 
1375     // Rebuild remembered sets of all regions.
1376     if (G1CollectedHeap::use_parallel_gc_threads()) {
1377       int n_workers =
1378         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1379                                        workers()->active_workers(),
1380                                        Threads::number_of_non_daemon_threads());
1381       assert(UseDynamicNumberOfGCThreads ||
1382              n_workers == workers()->total_workers(),
1383              "If not dynamic should be using all the  workers");
1384       workers()->set_active_workers(n_workers);
1385       // Set parallel threads in the heap (_n_par_threads) only
1386       // before a parallel phase and always reset it to 0 after
1387       // the phase so that the number of parallel threads does
1388       // no get carried forward to a serial phase where there
1389       // may be code that is "possibly_parallel".
1390       set_par_threads(n_workers);
1391 
1392       ParRebuildRSTask rebuild_rs_task(this);
1393       assert(check_heap_region_claim_values(
1394              HeapRegion::InitialClaimValue), "sanity check");
1395       assert(UseDynamicNumberOfGCThreads ||
1396              workers()->active_workers() == workers()->total_workers(),
1397         "Unless dynamic should use total workers");
1398       // Use the most recent number of  active workers
1399       assert(workers()->active_workers() > 0,
1400         "Active workers not properly set");
1401       set_par_threads(workers()->active_workers());
1402       workers()->run_task(&rebuild_rs_task);
1403       set_par_threads(0);
1404       assert(check_heap_region_claim_values(
1405              HeapRegion::RebuildRSClaimValue), "sanity check");
1406       reset_heap_region_claim_values();
1407     } else {
1408       RebuildRSOutOfRegionClosure rebuild_rs(this);
1409       heap_region_iterate(&rebuild_rs);
1410     }
1411 
1412     if (PrintGC) {
1413       print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1414     }
1415 
1416     if (true) { // FIXME
1417       // Ask the permanent generation to adjust size for full collections
1418       perm()->compute_new_size();
1419     }
1420 
1421     // Start a new incremental collection set for the next pause
1422     assert(g1_policy()->collection_set() == NULL, "must be");
1423     g1_policy()->start_incremental_cset_building();
1424 
1425     // Clear the _cset_fast_test bitmap in anticipation of adding
1426     // regions to the incremental collection set for the next
1427     // evacuation pause.
1428     clear_cset_fast_test();
1429 
1430     init_mutator_alloc_region();
1431 
1432     double end = os::elapsedTime();
1433     g1_policy()->record_full_collection_end();
1434 
1435 #ifdef TRACESPINNING
1436     ParallelTaskTerminator::print_termination_counts();
1437 #endif
1438 
1439     gc_epilogue(true);
1440 
1441     // Discard all rset updates
1442     JavaThread::dirty_card_queue_set().abandon_logs();
1443     assert(!G1DeferredRSUpdate
1444            || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1445   }
1446 
1447   _young_list->reset_sampled_info();
1448   // At this point there should be no regions in the
1449   // entire heap tagged as young.
1450   assert( check_young_list_empty(true /* check_heap */),
1451     "young list should be empty at this point");
1452 
1453   // Update the number of full collections that have been completed.
1454   increment_full_collections_completed(false /* concurrent */);
1455 
1456   _hrs.verify_optional();
1457   verify_region_sets_optional();
1458 
1459   if (PrintHeapAtGC) {
1460     Universe::print_heap_after_gc();
1461   }
1462   g1mm()->update_sizes();
1463   post_full_gc_dump();
1464 
1465   return true;
1466 }
1467 
1468 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1469   // do_collection() will return whether it succeeded in performing
1470   // the GC. Currently, there is no facility on the
1471   // do_full_collection() API to notify the caller than the collection
1472   // did not succeed (e.g., because it was locked out by the GC
1473   // locker). So, right now, we'll ignore the return value.
1474   bool dummy = do_collection(true,                /* explicit_gc */
1475                              clear_all_soft_refs,
1476                              0                    /* word_size */);
1477 }
1478 
1479 // This code is mostly copied from TenuredGeneration.
1480 void
1481 G1CollectedHeap::
1482 resize_if_necessary_after_full_collection(size_t word_size) {
1483   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1484 
1485   // Include the current allocation, if any, and bytes that will be
1486   // pre-allocated to support collections, as "used".
1487   const size_t used_after_gc = used();
1488   const size_t capacity_after_gc = capacity();
1489   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1490 
1491   // This is enforced in arguments.cpp.
1492   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1493          "otherwise the code below doesn't make sense");
1494 
1495   // We don't have floating point command-line arguments
1496   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1497   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1498   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1499   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1500 
1501   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1502   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1503 
1504   // We have to be careful here as these two calculations can overflow
1505   // 32-bit size_t's.
1506   double used_after_gc_d = (double) used_after_gc;
1507   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1508   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1509 
1510   // Let's make sure that they are both under the max heap size, which
1511   // by default will make them fit into a size_t.
1512   double desired_capacity_upper_bound = (double) max_heap_size;
1513   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1514                                     desired_capacity_upper_bound);
1515   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1516                                     desired_capacity_upper_bound);
1517 
1518   // We can now safely turn them into size_t's.
1519   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1520   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1521 
1522   // This assert only makes sense here, before we adjust them
1523   // with respect to the min and max heap size.
1524   assert(minimum_desired_capacity <= maximum_desired_capacity,
1525          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1526                  "maximum_desired_capacity = "SIZE_FORMAT,
1527                  minimum_desired_capacity, maximum_desired_capacity));
1528 
1529   // Should not be greater than the heap max size. No need to adjust
1530   // it with respect to the heap min size as it's a lower bound (i.e.,
1531   // we'll try to make the capacity larger than it, not smaller).
1532   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1533   // Should not be less than the heap min size. No need to adjust it
1534   // with respect to the heap max size as it's an upper bound (i.e.,
1535   // we'll try to make the capacity smaller than it, not greater).
1536   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1537 
1538   if (capacity_after_gc < minimum_desired_capacity) {
1539     // Don't expand unless it's significant
1540     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1541     ergo_verbose4(ErgoHeapSizing,
1542                   "attempt heap expansion",
1543                   ergo_format_reason("capacity lower than "
1544                                      "min desired capacity after Full GC")
1545                   ergo_format_byte("capacity")
1546                   ergo_format_byte("occupancy")
1547                   ergo_format_byte_perc("min desired capacity"),
1548                   capacity_after_gc, used_after_gc,
1549                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1550     expand(expand_bytes);
1551 
1552     // No expansion, now see if we want to shrink
1553   } else if (capacity_after_gc > maximum_desired_capacity) {
1554     // Capacity too large, compute shrinking size
1555     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1556     ergo_verbose4(ErgoHeapSizing,
1557                   "attempt heap shrinking",
1558                   ergo_format_reason("capacity higher than "
1559                                      "max desired capacity after Full GC")
1560                   ergo_format_byte("capacity")
1561                   ergo_format_byte("occupancy")
1562                   ergo_format_byte_perc("max desired capacity"),
1563                   capacity_after_gc, used_after_gc,
1564                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1565     shrink(shrink_bytes);
1566   }
1567 }
1568 
1569 
1570 HeapWord*
1571 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1572                                            bool* succeeded) {
1573   assert_at_safepoint(true /* should_be_vm_thread */);
1574 
1575   *succeeded = true;
1576   // Let's attempt the allocation first.
1577   HeapWord* result =
1578     attempt_allocation_at_safepoint(word_size,
1579                                  false /* expect_null_mutator_alloc_region */);
1580   if (result != NULL) {
1581     assert(*succeeded, "sanity");
1582     return result;
1583   }
1584 
1585   // In a G1 heap, we're supposed to keep allocation from failing by
1586   // incremental pauses.  Therefore, at least for now, we'll favor
1587   // expansion over collection.  (This might change in the future if we can
1588   // do something smarter than full collection to satisfy a failed alloc.)
1589   result = expand_and_allocate(word_size);
1590   if (result != NULL) {
1591     assert(*succeeded, "sanity");
1592     return result;
1593   }
1594 
1595   // Expansion didn't work, we'll try to do a Full GC.
1596   bool gc_succeeded = do_collection(false, /* explicit_gc */
1597                                     false, /* clear_all_soft_refs */
1598                                     word_size);
1599   if (!gc_succeeded) {
1600     *succeeded = false;
1601     return NULL;
1602   }
1603 
1604   // Retry the allocation
1605   result = attempt_allocation_at_safepoint(word_size,
1606                                   true /* expect_null_mutator_alloc_region */);
1607   if (result != NULL) {
1608     assert(*succeeded, "sanity");
1609     return result;
1610   }
1611 
1612   // Then, try a Full GC that will collect all soft references.
1613   gc_succeeded = do_collection(false, /* explicit_gc */
1614                                true,  /* clear_all_soft_refs */
1615                                word_size);
1616   if (!gc_succeeded) {
1617     *succeeded = false;
1618     return NULL;
1619   }
1620 
1621   // Retry the allocation once more
1622   result = attempt_allocation_at_safepoint(word_size,
1623                                   true /* expect_null_mutator_alloc_region */);
1624   if (result != NULL) {
1625     assert(*succeeded, "sanity");
1626     return result;
1627   }
1628 
1629   assert(!collector_policy()->should_clear_all_soft_refs(),
1630          "Flag should have been handled and cleared prior to this point");
1631 
1632   // What else?  We might try synchronous finalization later.  If the total
1633   // space available is large enough for the allocation, then a more
1634   // complete compaction phase than we've tried so far might be
1635   // appropriate.
1636   assert(*succeeded, "sanity");
1637   return NULL;
1638 }
1639 
1640 // Attempting to expand the heap sufficiently
1641 // to support an allocation of the given "word_size".  If
1642 // successful, perform the allocation and return the address of the
1643 // allocated block, or else "NULL".
1644 
1645 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1646   assert_at_safepoint(true /* should_be_vm_thread */);
1647 
1648   verify_region_sets_optional();
1649 
1650   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1651   ergo_verbose1(ErgoHeapSizing,
1652                 "attempt heap expansion",
1653                 ergo_format_reason("allocation request failed")
1654                 ergo_format_byte("allocation request"),
1655                 word_size * HeapWordSize);
1656   if (expand(expand_bytes)) {
1657     _hrs.verify_optional();
1658     verify_region_sets_optional();
1659     return attempt_allocation_at_safepoint(word_size,
1660                                  false /* expect_null_mutator_alloc_region */);
1661   }
1662   return NULL;
1663 }
1664 
1665 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1666                                              HeapWord* new_end) {
1667   assert(old_end != new_end, "don't call this otherwise");
1668   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1669 
1670   // Update the committed mem region.
1671   _g1_committed.set_end(new_end);
1672   // Tell the card table about the update.
1673   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1674   // Tell the BOT about the update.
1675   _bot_shared->resize(_g1_committed.word_size());
1676 }
1677 
1678 bool G1CollectedHeap::expand(size_t expand_bytes) {
1679   size_t old_mem_size = _g1_storage.committed_size();
1680   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1681   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1682                                        HeapRegion::GrainBytes);
1683   ergo_verbose2(ErgoHeapSizing,
1684                 "expand the heap",
1685                 ergo_format_byte("requested expansion amount")
1686                 ergo_format_byte("attempted expansion amount"),
1687                 expand_bytes, aligned_expand_bytes);
1688 
1689   // First commit the memory.
1690   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1691   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1692   if (successful) {
1693     // Then propagate this update to the necessary data structures.
1694     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1695     update_committed_space(old_end, new_end);
1696 
1697     FreeRegionList expansion_list("Local Expansion List");
1698     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1699     assert(mr.start() == old_end, "post-condition");
1700     // mr might be a smaller region than what was requested if
1701     // expand_by() was unable to allocate the HeapRegion instances
1702     assert(mr.end() <= new_end, "post-condition");
1703 
1704     size_t actual_expand_bytes = mr.byte_size();
1705     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1706     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1707            "post-condition");
1708     if (actual_expand_bytes < aligned_expand_bytes) {
1709       // We could not expand _hrs to the desired size. In this case we
1710       // need to shrink the committed space accordingly.
1711       assert(mr.end() < new_end, "invariant");
1712 
1713       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1714       // First uncommit the memory.
1715       _g1_storage.shrink_by(diff_bytes);
1716       // Then propagate this update to the necessary data structures.
1717       update_committed_space(new_end, mr.end());
1718     }
1719     _free_list.add_as_tail(&expansion_list);
1720 
1721     if (_hr_printer.is_active()) {
1722       HeapWord* curr = mr.start();
1723       while (curr < mr.end()) {
1724         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1725         _hr_printer.commit(curr, curr_end);
1726         curr = curr_end;
1727       }
1728       assert(curr == mr.end(), "post-condition");
1729     }
1730     g1_policy()->record_new_heap_size(n_regions());
1731   } else {
1732     ergo_verbose0(ErgoHeapSizing,
1733                   "did not expand the heap",
1734                   ergo_format_reason("heap expansion operation failed"));
1735     // The expansion of the virtual storage space was unsuccessful.
1736     // Let's see if it was because we ran out of swap.
1737     if (G1ExitOnExpansionFailure &&
1738         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1739       // We had head room...
1740       vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1741     }
1742   }
1743   return successful;
1744 }
1745 
1746 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1747   size_t old_mem_size = _g1_storage.committed_size();
1748   size_t aligned_shrink_bytes =
1749     ReservedSpace::page_align_size_down(shrink_bytes);
1750   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1751                                          HeapRegion::GrainBytes);
1752   size_t num_regions_deleted = 0;
1753   MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1754   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1755   assert(mr.end() == old_end, "post-condition");
1756 
1757   ergo_verbose3(ErgoHeapSizing,
1758                 "shrink the heap",
1759                 ergo_format_byte("requested shrinking amount")
1760                 ergo_format_byte("aligned shrinking amount")
1761                 ergo_format_byte("attempted shrinking amount"),
1762                 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1763   if (mr.byte_size() > 0) {
1764     if (_hr_printer.is_active()) {
1765       HeapWord* curr = mr.end();
1766       while (curr > mr.start()) {
1767         HeapWord* curr_end = curr;
1768         curr -= HeapRegion::GrainWords;
1769         _hr_printer.uncommit(curr, curr_end);
1770       }
1771       assert(curr == mr.start(), "post-condition");
1772     }
1773 
1774     _g1_storage.shrink_by(mr.byte_size());
1775     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1776     assert(mr.start() == new_end, "post-condition");
1777 
1778     _expansion_regions += num_regions_deleted;
1779     update_committed_space(old_end, new_end);
1780     HeapRegionRemSet::shrink_heap(n_regions());
1781     g1_policy()->record_new_heap_size(n_regions());
1782   } else {
1783     ergo_verbose0(ErgoHeapSizing,
1784                   "did not shrink the heap",
1785                   ergo_format_reason("heap shrinking operation failed"));
1786   }
1787 }
1788 
1789 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1790   verify_region_sets_optional();
1791 
1792   // We should only reach here at the end of a Full GC which means we
1793   // should not not be holding to any GC alloc regions. The method
1794   // below will make sure of that and do any remaining clean up.
1795   abandon_gc_alloc_regions();
1796 
1797   // Instead of tearing down / rebuilding the free lists here, we
1798   // could instead use the remove_all_pending() method on free_list to
1799   // remove only the ones that we need to remove.
1800   tear_down_region_sets(true /* free_list_only */);
1801   shrink_helper(shrink_bytes);
1802   rebuild_region_sets(true /* free_list_only */);
1803 
1804   _hrs.verify_optional();
1805   verify_region_sets_optional();
1806 }
1807 
1808 // Public methods.
1809 
1810 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1811 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1812 #endif // _MSC_VER
1813 
1814 
1815 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1816   SharedHeap(policy_),
1817   _g1_policy(policy_),
1818   _dirty_card_queue_set(false),
1819   _into_cset_dirty_card_queue_set(false),
1820   _is_alive_closure_cm(this),
1821   _is_alive_closure_stw(this),
1822   _ref_processor_cm(NULL),
1823   _ref_processor_stw(NULL),
1824   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1825   _bot_shared(NULL),
1826   _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1827   _evac_failure_scan_stack(NULL) ,
1828   _mark_in_progress(false),
1829   _cg1r(NULL), _summary_bytes_used(0),
1830   _g1mm(NULL),
1831   _refine_cte_cl(NULL),
1832   _full_collection(false),
1833   _free_list("Master Free List"),
1834   _secondary_free_list("Secondary Free List"),
1835   _old_set("Old Set"),
1836   _humongous_set("Master Humongous Set"),
1837   _free_regions_coming(false),
1838   _young_list(new YoungList(this)),
1839   _gc_time_stamp(0),
1840   _retained_old_gc_alloc_region(NULL),
1841   _surviving_young_words(NULL),
1842   _full_collections_completed(0),
1843   _in_cset_fast_test(NULL),
1844   _in_cset_fast_test_base(NULL),
1845   _dirty_cards_region_list(NULL) {
1846   _g1h = this; // To catch bugs.
1847   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1848     vm_exit_during_initialization("Failed necessary allocation.");
1849   }
1850 
1851   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1852 
1853   int n_queues = MAX2((int)ParallelGCThreads, 1);
1854   _task_queues = new RefToScanQueueSet(n_queues);
1855 
1856   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1857   assert(n_rem_sets > 0, "Invariant.");
1858 
1859   HeapRegionRemSetIterator** iter_arr =
1860     NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1861   for (int i = 0; i < n_queues; i++) {
1862     iter_arr[i] = new HeapRegionRemSetIterator();
1863   }
1864   _rem_set_iterator = iter_arr;
1865 
1866   for (int i = 0; i < n_queues; i++) {
1867     RefToScanQueue* q = new RefToScanQueue();
1868     q->initialize();
1869     _task_queues->register_queue(i, q);
1870   }
1871 
1872   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1873 }
1874 
1875 jint G1CollectedHeap::initialize() {
1876   CollectedHeap::pre_initialize();
1877   os::enable_vtime();
1878 
1879   // Necessary to satisfy locking discipline assertions.
1880 
1881   MutexLocker x(Heap_lock);
1882 
1883   // We have to initialize the printer before committing the heap, as
1884   // it will be used then.
1885   _hr_printer.set_active(G1PrintHeapRegions);
1886 
1887   // While there are no constraints in the GC code that HeapWordSize
1888   // be any particular value, there are multiple other areas in the
1889   // system which believe this to be true (e.g. oop->object_size in some
1890   // cases incorrectly returns the size in wordSize units rather than
1891   // HeapWordSize).
1892   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1893 
1894   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1895   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1896 
1897   // Ensure that the sizes are properly aligned.
1898   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1899   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1900 
1901   _cg1r = new ConcurrentG1Refine();
1902 
1903   // Reserve the maximum.
1904   PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1905   // Includes the perm-gen.
1906 
1907   // When compressed oops are enabled, the preferred heap base
1908   // is calculated by subtracting the requested size from the
1909   // 32Gb boundary and using the result as the base address for
1910   // heap reservation. If the requested size is not aligned to
1911   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1912   // into the ReservedHeapSpace constructor) then the actual
1913   // base of the reserved heap may end up differing from the
1914   // address that was requested (i.e. the preferred heap base).
1915   // If this happens then we could end up using a non-optimal
1916   // compressed oops mode.
1917 
1918   // Since max_byte_size is aligned to the size of a heap region (checked
1919   // above), we also need to align the perm gen size as it might not be.
1920   const size_t total_reserved = max_byte_size +
1921                                 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1922   Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1923 
1924   char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1925 
1926   ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1927                             UseLargePages, addr);
1928 
1929   if (UseCompressedOops) {
1930     if (addr != NULL && !heap_rs.is_reserved()) {
1931       // Failed to reserve at specified address - the requested memory
1932       // region is taken already, for example, by 'java' launcher.
1933       // Try again to reserver heap higher.
1934       addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1935 
1936       ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1937                                  UseLargePages, addr);
1938 
1939       if (addr != NULL && !heap_rs0.is_reserved()) {
1940         // Failed to reserve at specified address again - give up.
1941         addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1942         assert(addr == NULL, "");
1943 
1944         ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1945                                    UseLargePages, addr);
1946         heap_rs = heap_rs1;
1947       } else {
1948         heap_rs = heap_rs0;
1949       }
1950     }
1951   }
1952 
1953   if (!heap_rs.is_reserved()) {
1954     vm_exit_during_initialization("Could not reserve enough space for object heap");
1955     return JNI_ENOMEM;
1956   }
1957 
1958   // It is important to do this in a way such that concurrent readers can't
1959   // temporarily think somethings in the heap.  (I've actually seen this
1960   // happen in asserts: DLD.)
1961   _reserved.set_word_size(0);
1962   _reserved.set_start((HeapWord*)heap_rs.base());
1963   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1964 
1965   _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1966 
1967   // Create the gen rem set (and barrier set) for the entire reserved region.
1968   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1969   set_barrier_set(rem_set()->bs());
1970   if (barrier_set()->is_a(BarrierSet::ModRef)) {
1971     _mr_bs = (ModRefBarrierSet*)_barrier_set;
1972   } else {
1973     vm_exit_during_initialization("G1 requires a mod ref bs.");
1974     return JNI_ENOMEM;
1975   }
1976 
1977   // Also create a G1 rem set.
1978   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1979     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1980   } else {
1981     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1982     return JNI_ENOMEM;
1983   }
1984 
1985   // Carve out the G1 part of the heap.
1986 
1987   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
1988   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1989                            g1_rs.size()/HeapWordSize);
1990   ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1991 
1992   _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1993 
1994   _g1_storage.initialize(g1_rs, 0);
1995   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1996   _hrs.initialize((HeapWord*) _g1_reserved.start(),
1997                   (HeapWord*) _g1_reserved.end(),
1998                   _expansion_regions);
1999 
2000   // 6843694 - ensure that the maximum region index can fit
2001   // in the remembered set structures.
2002   const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2003   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2004 
2005   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2006   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2007   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2008             "too many cards per region");
2009 
2010   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2011 
2012   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2013                                              heap_word_size(init_byte_size));
2014 
2015   _g1h = this;
2016 
2017    _in_cset_fast_test_length = max_regions();
2018    _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2019 
2020    // We're biasing _in_cset_fast_test to avoid subtracting the
2021    // beginning of the heap every time we want to index; basically
2022    // it's the same with what we do with the card table.
2023    _in_cset_fast_test = _in_cset_fast_test_base -
2024                 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2025 
2026    // Clear the _cset_fast_test bitmap in anticipation of adding
2027    // regions to the incremental collection set for the first
2028    // evacuation pause.
2029    clear_cset_fast_test();
2030 
2031   // Create the ConcurrentMark data structure and thread.
2032   // (Must do this late, so that "max_regions" is defined.)
2033   _cm       = new ConcurrentMark(heap_rs, (int) max_regions());
2034   _cmThread = _cm->cmThread();
2035 
2036   // Initialize the from_card cache structure of HeapRegionRemSet.
2037   HeapRegionRemSet::init_heap(max_regions());
2038 
2039   // Now expand into the initial heap size.
2040   if (!expand(init_byte_size)) {
2041     vm_exit_during_initialization("Failed to allocate initial heap.");
2042     return JNI_ENOMEM;
2043   }
2044 
2045   // Perform any initialization actions delegated to the policy.
2046   g1_policy()->init();
2047 
2048   _refine_cte_cl =
2049     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2050                                     g1_rem_set(),
2051                                     concurrent_g1_refine());
2052   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2053 
2054   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2055                                                SATB_Q_FL_lock,
2056                                                G1SATBProcessCompletedThreshold,
2057                                                Shared_SATB_Q_lock);
2058 
2059   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2060                                                 DirtyCardQ_FL_lock,
2061                                                 concurrent_g1_refine()->yellow_zone(),
2062                                                 concurrent_g1_refine()->red_zone(),
2063                                                 Shared_DirtyCardQ_lock);
2064 
2065   if (G1DeferredRSUpdate) {
2066     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2067                                       DirtyCardQ_FL_lock,
2068                                       -1, // never trigger processing
2069                                       -1, // no limit on length
2070                                       Shared_DirtyCardQ_lock,
2071                                       &JavaThread::dirty_card_queue_set());
2072   }
2073 
2074   // Initialize the card queue set used to hold cards containing
2075   // references into the collection set.
2076   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2077                                              DirtyCardQ_FL_lock,
2078                                              -1, // never trigger processing
2079                                              -1, // no limit on length
2080                                              Shared_DirtyCardQ_lock,
2081                                              &JavaThread::dirty_card_queue_set());
2082 
2083   // In case we're keeping closure specialization stats, initialize those
2084   // counts and that mechanism.
2085   SpecializationStats::clear();
2086 
2087   // Do later initialization work for concurrent refinement.
2088   _cg1r->init();
2089 
2090   // Here we allocate the dummy full region that is required by the
2091   // G1AllocRegion class. If we don't pass an address in the reserved
2092   // space here, lots of asserts fire.
2093 
2094   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2095                                              _g1_reserved.start());
2096   // We'll re-use the same region whether the alloc region will
2097   // require BOT updates or not and, if it doesn't, then a non-young
2098   // region will complain that it cannot support allocations without
2099   // BOT updates. So we'll tag the dummy region as young to avoid that.
2100   dummy_region->set_young();
2101   // Make sure it's full.
2102   dummy_region->set_top(dummy_region->end());
2103   G1AllocRegion::setup(this, dummy_region);
2104 
2105   init_mutator_alloc_region();
2106 
2107   // Do create of the monitoring and management support so that
2108   // values in the heap have been properly initialized.
2109   _g1mm = new G1MonitoringSupport(this);
2110 
2111   return JNI_OK;
2112 }
2113 
2114 void G1CollectedHeap::ref_processing_init() {
2115   // Reference processing in G1 currently works as follows:
2116   //
2117   // * There are two reference processor instances. One is
2118   //   used to record and process discovered references
2119   //   during concurrent marking; the other is used to
2120   //   record and process references during STW pauses
2121   //   (both full and incremental).
2122   // * Both ref processors need to 'span' the entire heap as
2123   //   the regions in the collection set may be dotted around.
2124   //
2125   // * For the concurrent marking ref processor:
2126   //   * Reference discovery is enabled at initial marking.
2127   //   * Reference discovery is disabled and the discovered
2128   //     references processed etc during remarking.
2129   //   * Reference discovery is MT (see below).
2130   //   * Reference discovery requires a barrier (see below).
2131   //   * Reference processing may or may not be MT
2132   //     (depending on the value of ParallelRefProcEnabled
2133   //     and ParallelGCThreads).
2134   //   * A full GC disables reference discovery by the CM
2135   //     ref processor and abandons any entries on it's
2136   //     discovered lists.
2137   //
2138   // * For the STW processor:
2139   //   * Non MT discovery is enabled at the start of a full GC.
2140   //   * Processing and enqueueing during a full GC is non-MT.
2141   //   * During a full GC, references are processed after marking.
2142   //
2143   //   * Discovery (may or may not be MT) is enabled at the start
2144   //     of an incremental evacuation pause.
2145   //   * References are processed near the end of a STW evacuation pause.
2146   //   * For both types of GC:
2147   //     * Discovery is atomic - i.e. not concurrent.
2148   //     * Reference discovery will not need a barrier.
2149 
2150   SharedHeap::ref_processing_init();
2151   MemRegion mr = reserved_region();
2152 
2153   // Concurrent Mark ref processor
2154   _ref_processor_cm =
2155     new ReferenceProcessor(mr,    // span
2156                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2157                                 // mt processing
2158                            (int) ParallelGCThreads,
2159                                 // degree of mt processing
2160                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2161                                 // mt discovery
2162                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2163                                 // degree of mt discovery
2164                            false,
2165                                 // Reference discovery is not atomic
2166                            &_is_alive_closure_cm,
2167                                 // is alive closure
2168                                 // (for efficiency/performance)
2169                            true);
2170                                 // Setting next fields of discovered
2171                                 // lists requires a barrier.
2172 
2173   // STW ref processor
2174   _ref_processor_stw =
2175     new ReferenceProcessor(mr,    // span
2176                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2177                                 // mt processing
2178                            MAX2((int)ParallelGCThreads, 1),
2179                                 // degree of mt processing
2180                            (ParallelGCThreads > 1),
2181                                 // mt discovery
2182                            MAX2((int)ParallelGCThreads, 1),
2183                                 // degree of mt discovery
2184                            true,
2185                                 // Reference discovery is atomic
2186                            &_is_alive_closure_stw,
2187                                 // is alive closure
2188                                 // (for efficiency/performance)
2189                            false);
2190                                 // Setting next fields of discovered
2191                                 // lists requires a barrier.
2192 }
2193 
2194 size_t G1CollectedHeap::capacity() const {
2195   return _g1_committed.byte_size();
2196 }
2197 
2198 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2199                                                  DirtyCardQueue* into_cset_dcq,
2200                                                  bool concurrent,
2201                                                  int worker_i) {
2202   // Clean cards in the hot card cache
2203   concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2204 
2205   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2206   int n_completed_buffers = 0;
2207   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2208     n_completed_buffers++;
2209   }
2210   g1_policy()->record_update_rs_processed_buffers(worker_i,
2211                                                   (double) n_completed_buffers);
2212   dcqs.clear_n_completed_buffers();
2213   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2214 }
2215 
2216 
2217 // Computes the sum of the storage used by the various regions.
2218 
2219 size_t G1CollectedHeap::used() const {
2220   assert(Heap_lock->owner() != NULL,
2221          "Should be owned on this thread's behalf.");
2222   size_t result = _summary_bytes_used;
2223   // Read only once in case it is set to NULL concurrently
2224   HeapRegion* hr = _mutator_alloc_region.get();
2225   if (hr != NULL)
2226     result += hr->used();
2227   return result;
2228 }
2229 
2230 size_t G1CollectedHeap::used_unlocked() const {
2231   size_t result = _summary_bytes_used;
2232   return result;
2233 }
2234 
2235 class SumUsedClosure: public HeapRegionClosure {
2236   size_t _used;
2237 public:
2238   SumUsedClosure() : _used(0) {}
2239   bool doHeapRegion(HeapRegion* r) {
2240     if (!r->continuesHumongous()) {
2241       _used += r->used();
2242     }
2243     return false;
2244   }
2245   size_t result() { return _used; }
2246 };
2247 
2248 size_t G1CollectedHeap::recalculate_used() const {
2249   SumUsedClosure blk;
2250   heap_region_iterate(&blk);
2251   return blk.result();
2252 }
2253 
2254 size_t G1CollectedHeap::unsafe_max_alloc() {
2255   if (free_regions() > 0) return HeapRegion::GrainBytes;
2256   // otherwise, is there space in the current allocation region?
2257 
2258   // We need to store the current allocation region in a local variable
2259   // here. The problem is that this method doesn't take any locks and
2260   // there may be other threads which overwrite the current allocation
2261   // region field. attempt_allocation(), for example, sets it to NULL
2262   // and this can happen *after* the NULL check here but before the call
2263   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2264   // to be a problem in the optimized build, since the two loads of the
2265   // current allocation region field are optimized away.
2266   HeapRegion* hr = _mutator_alloc_region.get();
2267   if (hr == NULL) {
2268     return 0;
2269   }
2270   return hr->free();
2271 }
2272 
2273 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2274   return
2275     ((cause == GCCause::_gc_locker           && GCLockerInvokesConcurrent) ||
2276      (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2277 }
2278 
2279 #ifndef PRODUCT
2280 void G1CollectedHeap::allocate_dummy_regions() {
2281   // Let's fill up most of the region
2282   size_t word_size = HeapRegion::GrainWords - 1024;
2283   // And as a result the region we'll allocate will be humongous.
2284   guarantee(isHumongous(word_size), "sanity");
2285 
2286   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2287     // Let's use the existing mechanism for the allocation
2288     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2289     if (dummy_obj != NULL) {
2290       MemRegion mr(dummy_obj, word_size);
2291       CollectedHeap::fill_with_object(mr);
2292     } else {
2293       // If we can't allocate once, we probably cannot allocate
2294       // again. Let's get out of the loop.
2295       break;
2296     }
2297   }
2298 }
2299 #endif // !PRODUCT
2300 
2301 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2302   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2303 
2304   // We assume that if concurrent == true, then the caller is a
2305   // concurrent thread that was joined the Suspendible Thread
2306   // Set. If there's ever a cheap way to check this, we should add an
2307   // assert here.
2308 
2309   // We have already incremented _total_full_collections at the start
2310   // of the GC, so total_full_collections() represents how many full
2311   // collections have been started.
2312   unsigned int full_collections_started = total_full_collections();
2313 
2314   // Given that this method is called at the end of a Full GC or of a
2315   // concurrent cycle, and those can be nested (i.e., a Full GC can
2316   // interrupt a concurrent cycle), the number of full collections
2317   // completed should be either one (in the case where there was no
2318   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2319   // behind the number of full collections started.
2320 
2321   // This is the case for the inner caller, i.e. a Full GC.
2322   assert(concurrent ||
2323          (full_collections_started == _full_collections_completed + 1) ||
2324          (full_collections_started == _full_collections_completed + 2),
2325          err_msg("for inner caller (Full GC): full_collections_started = %u "
2326                  "is inconsistent with _full_collections_completed = %u",
2327                  full_collections_started, _full_collections_completed));
2328 
2329   // This is the case for the outer caller, i.e. the concurrent cycle.
2330   assert(!concurrent ||
2331          (full_collections_started == _full_collections_completed + 1),
2332          err_msg("for outer caller (concurrent cycle): "
2333                  "full_collections_started = %u "
2334                  "is inconsistent with _full_collections_completed = %u",
2335                  full_collections_started, _full_collections_completed));
2336 
2337   _full_collections_completed += 1;
2338 
2339   // We need to clear the "in_progress" flag in the CM thread before
2340   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2341   // is set) so that if a waiter requests another System.gc() it doesn't
2342   // incorrectly see that a marking cyle is still in progress.
2343   if (concurrent) {
2344     _cmThread->clear_in_progress();
2345   }
2346 
2347   // This notify_all() will ensure that a thread that called
2348   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2349   // and it's waiting for a full GC to finish will be woken up. It is
2350   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2351   FullGCCount_lock->notify_all();
2352 }
2353 
2354 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2355   assert_at_safepoint(true /* should_be_vm_thread */);
2356   GCCauseSetter gcs(this, cause);
2357   switch (cause) {
2358     case GCCause::_heap_inspection:
2359     case GCCause::_heap_dump: {
2360       HandleMark hm;
2361       do_full_collection(false);         // don't clear all soft refs
2362       break;
2363     }
2364     default: // XXX FIX ME
2365       ShouldNotReachHere(); // Unexpected use of this function
2366   }
2367 }
2368 
2369 void G1CollectedHeap::collect(GCCause::Cause cause) {
2370   // The caller doesn't have the Heap_lock
2371   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2372 
2373   unsigned int gc_count_before;
2374   unsigned int full_gc_count_before;
2375   {
2376     MutexLocker ml(Heap_lock);
2377 
2378     // Read the GC count while holding the Heap_lock
2379     gc_count_before = SharedHeap::heap()->total_collections();
2380     full_gc_count_before = SharedHeap::heap()->total_full_collections();
2381   }
2382 
2383   if (should_do_concurrent_full_gc(cause)) {
2384     // Schedule an initial-mark evacuation pause that will start a
2385     // concurrent cycle. We're setting word_size to 0 which means that
2386     // we are not requesting a post-GC allocation.
2387     VM_G1IncCollectionPause op(gc_count_before,
2388                                0,     /* word_size */
2389                                true,  /* should_initiate_conc_mark */
2390                                g1_policy()->max_pause_time_ms(),
2391                                cause);
2392     VMThread::execute(&op);
2393   } else {
2394     if (cause == GCCause::_gc_locker
2395         DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2396 
2397       // Schedule a standard evacuation pause. We're setting word_size
2398       // to 0 which means that we are not requesting a post-GC allocation.
2399       VM_G1IncCollectionPause op(gc_count_before,
2400                                  0,     /* word_size */
2401                                  false, /* should_initiate_conc_mark */
2402                                  g1_policy()->max_pause_time_ms(),
2403                                  cause);
2404       VMThread::execute(&op);
2405     } else {
2406       // Schedule a Full GC.
2407       VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2408       VMThread::execute(&op);
2409     }
2410   }
2411 }
2412 
2413 bool G1CollectedHeap::is_in(const void* p) const {
2414   HeapRegion* hr = _hrs.addr_to_region((HeapWord*) p);
2415   if (hr != NULL) {
2416     return hr->is_in(p);
2417   } else {
2418     return _perm_gen->as_gen()->is_in(p);
2419   }
2420 }
2421 
2422 // Iteration functions.
2423 
2424 // Iterates an OopClosure over all ref-containing fields of objects
2425 // within a HeapRegion.
2426 
2427 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2428   MemRegion _mr;
2429   OopClosure* _cl;
2430 public:
2431   IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2432     : _mr(mr), _cl(cl) {}
2433   bool doHeapRegion(HeapRegion* r) {
2434     if (! r->continuesHumongous()) {
2435       r->oop_iterate(_cl);
2436     }
2437     return false;
2438   }
2439 };
2440 
2441 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2442   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2443   heap_region_iterate(&blk);
2444   if (do_perm) {
2445     perm_gen()->oop_iterate(cl);
2446   }
2447 }
2448 
2449 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2450   IterateOopClosureRegionClosure blk(mr, cl);
2451   heap_region_iterate(&blk);
2452   if (do_perm) {
2453     perm_gen()->oop_iterate(cl);
2454   }
2455 }
2456 
2457 // Iterates an ObjectClosure over all objects within a HeapRegion.
2458 
2459 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2460   ObjectClosure* _cl;
2461 public:
2462   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2463   bool doHeapRegion(HeapRegion* r) {
2464     if (! r->continuesHumongous()) {
2465       r->object_iterate(_cl);
2466     }
2467     return false;
2468   }
2469 };
2470 
2471 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2472   IterateObjectClosureRegionClosure blk(cl);
2473   heap_region_iterate(&blk);
2474   if (do_perm) {
2475     perm_gen()->object_iterate(cl);
2476   }
2477 }
2478 
2479 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2480   // FIXME: is this right?
2481   guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2482 }
2483 
2484 // Calls a SpaceClosure on a HeapRegion.
2485 
2486 class SpaceClosureRegionClosure: public HeapRegionClosure {
2487   SpaceClosure* _cl;
2488 public:
2489   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2490   bool doHeapRegion(HeapRegion* r) {
2491     _cl->do_space(r);
2492     return false;
2493   }
2494 };
2495 
2496 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2497   SpaceClosureRegionClosure blk(cl);
2498   heap_region_iterate(&blk);
2499 }
2500 
2501 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2502   _hrs.iterate(cl);
2503 }
2504 
2505 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2506                                                HeapRegionClosure* cl) const {
2507   _hrs.iterate_from(r, cl);
2508 }
2509 
2510 void
2511 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2512                                                  int worker,
2513                                                  int no_of_par_workers,
2514                                                  jint claim_value) {
2515   const size_t regions = n_regions();
2516   const size_t max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2517                              no_of_par_workers :
2518                              1);
2519   assert(UseDynamicNumberOfGCThreads ||
2520          no_of_par_workers == workers()->total_workers(),
2521          "Non dynamic should use fixed number of workers");
2522   // try to spread out the starting points of the workers
2523   const size_t start_index = regions / max_workers * (size_t) worker;
2524 
2525   // each worker will actually look at all regions
2526   for (size_t count = 0; count < regions; ++count) {
2527     const size_t index = (start_index + count) % regions;
2528     assert(0 <= index && index < regions, "sanity");
2529     HeapRegion* r = region_at(index);
2530     // we'll ignore "continues humongous" regions (we'll process them
2531     // when we come across their corresponding "start humongous"
2532     // region) and regions already claimed
2533     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2534       continue;
2535     }
2536     // OK, try to claim it
2537     if (r->claimHeapRegion(claim_value)) {
2538       // success!
2539       assert(!r->continuesHumongous(), "sanity");
2540       if (r->startsHumongous()) {
2541         // If the region is "starts humongous" we'll iterate over its
2542         // "continues humongous" first; in fact we'll do them
2543         // first. The order is important. In on case, calling the
2544         // closure on the "starts humongous" region might de-allocate
2545         // and clear all its "continues humongous" regions and, as a
2546         // result, we might end up processing them twice. So, we'll do
2547         // them first (notice: most closures will ignore them anyway) and
2548         // then we'll do the "starts humongous" region.
2549         for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2550           HeapRegion* chr = region_at(ch_index);
2551 
2552           // if the region has already been claimed or it's not
2553           // "continues humongous" we're done
2554           if (chr->claim_value() == claim_value ||
2555               !chr->continuesHumongous()) {
2556             break;
2557           }
2558 
2559           // Noone should have claimed it directly. We can given
2560           // that we claimed its "starts humongous" region.
2561           assert(chr->claim_value() != claim_value, "sanity");
2562           assert(chr->humongous_start_region() == r, "sanity");
2563 
2564           if (chr->claimHeapRegion(claim_value)) {
2565             // we should always be able to claim it; noone else should
2566             // be trying to claim this region
2567 
2568             bool res2 = cl->doHeapRegion(chr);
2569             assert(!res2, "Should not abort");
2570 
2571             // Right now, this holds (i.e., no closure that actually
2572             // does something with "continues humongous" regions
2573             // clears them). We might have to weaken it in the future,
2574             // but let's leave these two asserts here for extra safety.
2575             assert(chr->continuesHumongous(), "should still be the case");
2576             assert(chr->humongous_start_region() == r, "sanity");
2577           } else {
2578             guarantee(false, "we should not reach here");
2579           }
2580         }
2581       }
2582 
2583       assert(!r->continuesHumongous(), "sanity");
2584       bool res = cl->doHeapRegion(r);
2585       assert(!res, "Should not abort");
2586     }
2587   }
2588 }
2589 
2590 class ResetClaimValuesClosure: public HeapRegionClosure {
2591 public:
2592   bool doHeapRegion(HeapRegion* r) {
2593     r->set_claim_value(HeapRegion::InitialClaimValue);
2594     return false;
2595   }
2596 };
2597 
2598 void
2599 G1CollectedHeap::reset_heap_region_claim_values() {
2600   ResetClaimValuesClosure blk;
2601   heap_region_iterate(&blk);
2602 }
2603 
2604 #ifdef ASSERT
2605 // This checks whether all regions in the heap have the correct claim
2606 // value. I also piggy-backed on this a check to ensure that the
2607 // humongous_start_region() information on "continues humongous"
2608 // regions is correct.
2609 
2610 class CheckClaimValuesClosure : public HeapRegionClosure {
2611 private:
2612   jint _claim_value;
2613   size_t _failures;
2614   HeapRegion* _sh_region;
2615 public:
2616   CheckClaimValuesClosure(jint claim_value) :
2617     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2618   bool doHeapRegion(HeapRegion* r) {
2619     if (r->claim_value() != _claim_value) {
2620       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2621                              "claim value = %d, should be %d",
2622                              HR_FORMAT_PARAMS(r),
2623                              r->claim_value(), _claim_value);
2624       ++_failures;
2625     }
2626     if (!r->isHumongous()) {
2627       _sh_region = NULL;
2628     } else if (r->startsHumongous()) {
2629       _sh_region = r;
2630     } else if (r->continuesHumongous()) {
2631       if (r->humongous_start_region() != _sh_region) {
2632         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2633                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2634                                HR_FORMAT_PARAMS(r),
2635                                r->humongous_start_region(),
2636                                _sh_region);
2637         ++_failures;
2638       }
2639     }
2640     return false;
2641   }
2642   size_t failures() {
2643     return _failures;
2644   }
2645 };
2646 
2647 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2648   CheckClaimValuesClosure cl(claim_value);
2649   heap_region_iterate(&cl);
2650   return cl.failures() == 0;
2651 }
2652 
2653 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2654   jint   _claim_value;
2655   size_t _failures;
2656 
2657 public:
2658   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2659     _claim_value(claim_value),
2660     _failures(0) { }
2661 
2662   size_t failures() {
2663     return _failures;
2664   }
2665 
2666   bool doHeapRegion(HeapRegion* hr) {
2667     assert(hr->in_collection_set(), "how?");
2668     assert(!hr->isHumongous(), "H-region in CSet");
2669     if (hr->claim_value() != _claim_value) {
2670       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2671                              "claim value = %d, should be %d",
2672                              HR_FORMAT_PARAMS(hr),
2673                              hr->claim_value(), _claim_value);
2674       _failures += 1;
2675     }
2676     return false;
2677   }
2678 };
2679 
2680 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2681   CheckClaimValuesInCSetHRClosure cl(claim_value);
2682   collection_set_iterate(&cl);
2683   return cl.failures() == 0;
2684 }
2685 #endif // ASSERT
2686 
2687 // We want the parallel threads to start their collection
2688 // set iteration at different collection set regions to
2689 // avoid contention.
2690 // If we have:
2691 //          n collection set regions
2692 //          p threads
2693 // Then thread t will start at region t * floor (n/p)
2694 
2695 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2696   HeapRegion* result = g1_policy()->collection_set();
2697   if (G1CollectedHeap::use_parallel_gc_threads()) {
2698     size_t cs_size = g1_policy()->cset_region_length();
2699     int n_workers = workers()->total_workers();
2700     size_t cs_spans = cs_size / n_workers;
2701     size_t ind      = cs_spans * worker_i;
2702     for (size_t i = 0; i < ind; i++) {
2703       result = result->next_in_collection_set();
2704     }
2705   }
2706   return result;
2707 }
2708 
2709 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2710   HeapRegion* r = g1_policy()->collection_set();
2711   while (r != NULL) {
2712     HeapRegion* next = r->next_in_collection_set();
2713     if (cl->doHeapRegion(r)) {
2714       cl->incomplete();
2715       return;
2716     }
2717     r = next;
2718   }
2719 }
2720 
2721 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2722                                                   HeapRegionClosure *cl) {
2723   if (r == NULL) {
2724     // The CSet is empty so there's nothing to do.
2725     return;
2726   }
2727 
2728   assert(r->in_collection_set(),
2729          "Start region must be a member of the collection set.");
2730   HeapRegion* cur = r;
2731   while (cur != NULL) {
2732     HeapRegion* next = cur->next_in_collection_set();
2733     if (cl->doHeapRegion(cur) && false) {
2734       cl->incomplete();
2735       return;
2736     }
2737     cur = next;
2738   }
2739   cur = g1_policy()->collection_set();
2740   while (cur != r) {
2741     HeapRegion* next = cur->next_in_collection_set();
2742     if (cl->doHeapRegion(cur) && false) {
2743       cl->incomplete();
2744       return;
2745     }
2746     cur = next;
2747   }
2748 }
2749 
2750 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2751   return n_regions() > 0 ? region_at(0) : NULL;
2752 }
2753 
2754 
2755 Space* G1CollectedHeap::space_containing(const void* addr) const {
2756   Space* res = heap_region_containing(addr);
2757   if (res == NULL)
2758     res = perm_gen()->space_containing(addr);
2759   return res;
2760 }
2761 
2762 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2763   Space* sp = space_containing(addr);
2764   if (sp != NULL) {
2765     return sp->block_start(addr);
2766   }
2767   return NULL;
2768 }
2769 
2770 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2771   Space* sp = space_containing(addr);
2772   assert(sp != NULL, "block_size of address outside of heap");
2773   return sp->block_size(addr);
2774 }
2775 
2776 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2777   Space* sp = space_containing(addr);
2778   return sp->block_is_obj(addr);
2779 }
2780 
2781 bool G1CollectedHeap::supports_tlab_allocation() const {
2782   return true;
2783 }
2784 
2785 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2786   return HeapRegion::GrainBytes;
2787 }
2788 
2789 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2790   // Return the remaining space in the cur alloc region, but not less than
2791   // the min TLAB size.
2792 
2793   // Also, this value can be at most the humongous object threshold,
2794   // since we can't allow tlabs to grow big enough to accomodate
2795   // humongous objects.
2796 
2797   HeapRegion* hr = _mutator_alloc_region.get();
2798   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2799   if (hr == NULL) {
2800     return max_tlab_size;
2801   } else {
2802     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2803   }
2804 }
2805 
2806 size_t G1CollectedHeap::max_capacity() const {
2807   return _g1_reserved.byte_size();
2808 }
2809 
2810 jlong G1CollectedHeap::millis_since_last_gc() {
2811   // assert(false, "NYI");
2812   return 0;
2813 }
2814 
2815 void G1CollectedHeap::prepare_for_verify() {
2816   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2817     ensure_parsability(false);
2818   }
2819   g1_rem_set()->prepare_for_verify();
2820 }
2821 
2822 class VerifyLivenessOopClosure: public OopClosure {
2823   G1CollectedHeap* _g1h;
2824   VerifyOption _vo;
2825 public:
2826   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2827     _g1h(g1h), _vo(vo)
2828   { }
2829   void do_oop(narrowOop *p) { do_oop_work(p); }
2830   void do_oop(      oop *p) { do_oop_work(p); }
2831 
2832   template <class T> void do_oop_work(T *p) {
2833     oop obj = oopDesc::load_decode_heap_oop(p);
2834     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2835               "Dead object referenced by a not dead object");
2836   }
2837 };
2838 
2839 class VerifyObjsInRegionClosure: public ObjectClosure {
2840 private:
2841   G1CollectedHeap* _g1h;
2842   size_t _live_bytes;
2843   HeapRegion *_hr;
2844   VerifyOption _vo;
2845 public:
2846   // _vo == UsePrevMarking -> use "prev" marking information,
2847   // _vo == UseNextMarking -> use "next" marking information,
2848   // _vo == UseMarkWord    -> use mark word from object header.
2849   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2850     : _live_bytes(0), _hr(hr), _vo(vo) {
2851     _g1h = G1CollectedHeap::heap();
2852   }
2853   void do_object(oop o) {
2854     VerifyLivenessOopClosure isLive(_g1h, _vo);
2855     assert(o != NULL, "Huh?");
2856     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2857       // If the object is alive according to the mark word,
2858       // then verify that the marking information agrees.
2859       // Note we can't verify the contra-positive of the
2860       // above: if the object is dead (according to the mark
2861       // word), it may not be marked, or may have been marked
2862       // but has since became dead, or may have been allocated
2863       // since the last marking.
2864       if (_vo == VerifyOption_G1UseMarkWord) {
2865         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2866       }
2867 
2868       o->oop_iterate(&isLive);
2869       if (!_hr->obj_allocated_since_prev_marking(o)) {
2870         size_t obj_size = o->size();    // Make sure we don't overflow
2871         _live_bytes += (obj_size * HeapWordSize);
2872       }
2873     }
2874   }
2875   size_t live_bytes() { return _live_bytes; }
2876 };
2877 
2878 class PrintObjsInRegionClosure : public ObjectClosure {
2879   HeapRegion *_hr;
2880   G1CollectedHeap *_g1;
2881 public:
2882   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2883     _g1 = G1CollectedHeap::heap();
2884   };
2885 
2886   void do_object(oop o) {
2887     if (o != NULL) {
2888       HeapWord *start = (HeapWord *) o;
2889       size_t word_sz = o->size();
2890       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2891                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2892                           (void*) o, word_sz,
2893                           _g1->isMarkedPrev(o),
2894                           _g1->isMarkedNext(o),
2895                           _hr->obj_allocated_since_prev_marking(o));
2896       HeapWord *end = start + word_sz;
2897       HeapWord *cur;
2898       int *val;
2899       for (cur = start; cur < end; cur++) {
2900         val = (int *) cur;
2901         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2902       }
2903     }
2904   }
2905 };
2906 
2907 class VerifyRegionClosure: public HeapRegionClosure {
2908 private:
2909   bool         _allow_dirty;
2910   bool         _par;
2911   VerifyOption _vo;
2912   bool         _failures;
2913 public:
2914   // _vo == UsePrevMarking -> use "prev" marking information,
2915   // _vo == UseNextMarking -> use "next" marking information,
2916   // _vo == UseMarkWord    -> use mark word from object header.
2917   VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
2918     : _allow_dirty(allow_dirty),
2919       _par(par),
2920       _vo(vo),
2921       _failures(false) {}
2922 
2923   bool failures() {
2924     return _failures;
2925   }
2926 
2927   bool doHeapRegion(HeapRegion* r) {
2928     guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2929               "Should be unclaimed at verify points.");
2930     if (!r->continuesHumongous()) {
2931       bool failures = false;
2932       r->verify(_allow_dirty, _vo, &failures);
2933       if (failures) {
2934         _failures = true;
2935       } else {
2936         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2937         r->object_iterate(&not_dead_yet_cl);
2938         if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2939           gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2940                                  "max_live_bytes "SIZE_FORMAT" "
2941                                  "< calculated "SIZE_FORMAT,
2942                                  r->bottom(), r->end(),
2943                                  r->max_live_bytes(),
2944                                  not_dead_yet_cl.live_bytes());
2945           _failures = true;
2946         }
2947       }
2948     }
2949     return false; // stop the region iteration if we hit a failure
2950   }
2951 };
2952 
2953 class VerifyRootsClosure: public OopsInGenClosure {
2954 private:
2955   G1CollectedHeap* _g1h;
2956   VerifyOption     _vo;
2957   bool             _failures;
2958 public:
2959   // _vo == UsePrevMarking -> use "prev" marking information,
2960   // _vo == UseNextMarking -> use "next" marking information,
2961   // _vo == UseMarkWord    -> use mark word from object header.
2962   VerifyRootsClosure(VerifyOption vo) :
2963     _g1h(G1CollectedHeap::heap()),
2964     _vo(vo),
2965     _failures(false) { }
2966 
2967   bool failures() { return _failures; }
2968 
2969   template <class T> void do_oop_nv(T* p) {
2970     T heap_oop = oopDesc::load_heap_oop(p);
2971     if (!oopDesc::is_null(heap_oop)) {
2972       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2973       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2974         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2975                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2976         if (_vo == VerifyOption_G1UseMarkWord) {
2977           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2978         }
2979         obj->print_on(gclog_or_tty);
2980         _failures = true;
2981       }
2982     }
2983   }
2984 
2985   void do_oop(oop* p)       { do_oop_nv(p); }
2986   void do_oop(narrowOop* p) { do_oop_nv(p); }
2987 };
2988 
2989 // This is the task used for parallel heap verification.
2990 
2991 class G1ParVerifyTask: public AbstractGangTask {
2992 private:
2993   G1CollectedHeap* _g1h;
2994   bool             _allow_dirty;
2995   VerifyOption     _vo;
2996   bool             _failures;
2997 
2998 public:
2999   // _vo == UsePrevMarking -> use "prev" marking information,
3000   // _vo == UseNextMarking -> use "next" marking information,
3001   // _vo == UseMarkWord    -> use mark word from object header.
3002   G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
3003     AbstractGangTask("Parallel verify task"),
3004     _g1h(g1h),
3005     _allow_dirty(allow_dirty),
3006     _vo(vo),
3007     _failures(false) { }
3008 
3009   bool failures() {
3010     return _failures;
3011   }
3012 
3013   void work(int worker_i) {
3014     HandleMark hm;
3015     VerifyRegionClosure blk(_allow_dirty, true, _vo);
3016     _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
3017                                           _g1h->workers()->active_workers(),
3018                                           HeapRegion::ParVerifyClaimValue);
3019     if (blk.failures()) {
3020       _failures = true;
3021     }
3022   }
3023 };
3024 
3025 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
3026   verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
3027 }
3028 
3029 void G1CollectedHeap::verify(bool allow_dirty,
3030                              bool silent,
3031                              VerifyOption vo) {
3032   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3033     if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3034     VerifyRootsClosure rootsCl(vo);
3035 
3036     assert(Thread::current()->is_VM_thread(),
3037       "Expected to be executed serially by the VM thread at this point");
3038 
3039     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3040 
3041     // We apply the relevant closures to all the oops in the
3042     // system dictionary, the string table and the code cache.
3043     const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
3044 
3045     process_strong_roots(true,      // activate StrongRootsScope
3046                          true,      // we set "collecting perm gen" to true,
3047                                     // so we don't reset the dirty cards in the perm gen.
3048                          SharedHeap::ScanningOption(so),  // roots scanning options
3049                          &rootsCl,
3050                          &blobsCl,
3051                          &rootsCl);
3052 
3053     // If we're verifying after the marking phase of a Full GC then we can't
3054     // treat the perm gen as roots into the G1 heap. Some of the objects in
3055     // the perm gen may be dead and hence not marked. If one of these dead
3056     // objects is considered to be a root then we may end up with a false
3057     // "Root location <x> points to dead ob <y>" failure.
3058     if (vo != VerifyOption_G1UseMarkWord) {
3059       // Since we used "collecting_perm_gen" == true above, we will not have
3060       // checked the refs from perm into the G1-collected heap. We check those
3061       // references explicitly below. Whether the relevant cards are dirty
3062       // is checked further below in the rem set verification.
3063       if (!silent) { gclog_or_tty->print("Permgen roots "); }
3064       perm_gen()->oop_iterate(&rootsCl);
3065     }
3066     bool failures = rootsCl.failures();
3067 
3068     if (vo != VerifyOption_G1UseMarkWord) {
3069       // If we're verifying during a full GC then the region sets
3070       // will have been torn down at the start of the GC. Therefore
3071       // verifying the region sets will fail. So we only verify
3072       // the region sets when not in a full GC.
3073       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3074       verify_region_sets();
3075     }
3076 
3077     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3078     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3079       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3080              "sanity check");
3081 
3082       G1ParVerifyTask task(this, allow_dirty, vo);
3083       assert(UseDynamicNumberOfGCThreads ||
3084         workers()->active_workers() == workers()->total_workers(),
3085         "If not dynamic should be using all the workers");
3086       int n_workers = workers()->active_workers();
3087       set_par_threads(n_workers);
3088       workers()->run_task(&task);
3089       set_par_threads(0);
3090       if (task.failures()) {
3091         failures = true;
3092       }
3093 
3094       // Checks that the expected amount of parallel work was done.
3095       // The implication is that n_workers is > 0.
3096       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3097              "sanity check");
3098 
3099       reset_heap_region_claim_values();
3100 
3101       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3102              "sanity check");
3103     } else {
3104       VerifyRegionClosure blk(allow_dirty, false, vo);
3105       heap_region_iterate(&blk);
3106       if (blk.failures()) {
3107         failures = true;
3108       }
3109     }
3110     if (!silent) gclog_or_tty->print("RemSet ");
3111     rem_set()->verify();
3112 
3113     if (failures) {
3114       gclog_or_tty->print_cr("Heap:");
3115       // It helps to have the per-region information in the output to
3116       // help us track down what went wrong. This is why we call
3117       // print_extended_on() instead of print_on().
3118       print_extended_on(gclog_or_tty);
3119       gclog_or_tty->print_cr("");
3120 #ifndef PRODUCT
3121       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3122         concurrent_mark()->print_reachable("at-verification-failure",
3123                                            vo, false /* all */);
3124       }
3125 #endif
3126       gclog_or_tty->flush();
3127     }
3128     guarantee(!failures, "there should not have been any failures");
3129   } else {
3130     if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3131   }
3132 }
3133 
3134 class PrintRegionClosure: public HeapRegionClosure {
3135   outputStream* _st;
3136 public:
3137   PrintRegionClosure(outputStream* st) : _st(st) {}
3138   bool doHeapRegion(HeapRegion* r) {
3139     r->print_on(_st);
3140     return false;
3141   }
3142 };
3143 
3144 void G1CollectedHeap::print_on(outputStream* st) const {
3145   st->print(" %-20s", "garbage-first heap");
3146   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3147             capacity()/K, used_unlocked()/K);
3148   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3149             _g1_storage.low_boundary(),
3150             _g1_storage.high(),
3151             _g1_storage.high_boundary());
3152   st->cr();
3153   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3154   size_t young_regions = _young_list->length();
3155   st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3156             young_regions, young_regions * HeapRegion::GrainBytes / K);
3157   size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3158   st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3159             survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3160   st->cr();
3161   perm()->as_gen()->print_on(st);
3162 }
3163 
3164 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3165   print_on(st);
3166 
3167   // Print the per-region information.
3168   st->cr();
3169   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), HS=humongous(starts), HC=humongous(continues), CS=collection set, F=free, TS=gc time stamp, PTAMS=previous top-at-mark-start, NTAMS=next top-at-mark-start)");
3170   PrintRegionClosure blk(st);
3171   heap_region_iterate(&blk);
3172 }
3173 
3174 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3175   if (G1CollectedHeap::use_parallel_gc_threads()) {
3176     workers()->print_worker_threads_on(st);
3177   }
3178   _cmThread->print_on(st);
3179   st->cr();
3180   _cm->print_worker_threads_on(st);
3181   _cg1r->print_worker_threads_on(st);
3182   st->cr();
3183 }
3184 
3185 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3186   if (G1CollectedHeap::use_parallel_gc_threads()) {
3187     workers()->threads_do(tc);
3188   }
3189   tc->do_thread(_cmThread);
3190   _cg1r->threads_do(tc);
3191 }
3192 
3193 void G1CollectedHeap::print_tracing_info() const {
3194   // We'll overload this to mean "trace GC pause statistics."
3195   if (TraceGen0Time || TraceGen1Time) {
3196     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3197     // to that.
3198     g1_policy()->print_tracing_info();
3199   }
3200   if (G1SummarizeRSetStats) {
3201     g1_rem_set()->print_summary_info();
3202   }
3203   if (G1SummarizeConcMark) {
3204     concurrent_mark()->print_summary_info();
3205   }
3206   g1_policy()->print_yg_surv_rate_info();
3207   SpecializationStats::print();
3208 }
3209 
3210 #ifndef PRODUCT
3211 // Helpful for debugging RSet issues.
3212 
3213 class PrintRSetsClosure : public HeapRegionClosure {
3214 private:
3215   const char* _msg;
3216   size_t _occupied_sum;
3217 
3218 public:
3219   bool doHeapRegion(HeapRegion* r) {
3220     HeapRegionRemSet* hrrs = r->rem_set();
3221     size_t occupied = hrrs->occupied();
3222     _occupied_sum += occupied;
3223 
3224     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3225                            HR_FORMAT_PARAMS(r));
3226     if (occupied == 0) {
3227       gclog_or_tty->print_cr("  RSet is empty");
3228     } else {
3229       hrrs->print();
3230     }
3231     gclog_or_tty->print_cr("----------");
3232     return false;
3233   }
3234 
3235   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3236     gclog_or_tty->cr();
3237     gclog_or_tty->print_cr("========================================");
3238     gclog_or_tty->print_cr(msg);
3239     gclog_or_tty->cr();
3240   }
3241 
3242   ~PrintRSetsClosure() {
3243     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3244     gclog_or_tty->print_cr("========================================");
3245     gclog_or_tty->cr();
3246   }
3247 };
3248 
3249 void G1CollectedHeap::print_cset_rsets() {
3250   PrintRSetsClosure cl("Printing CSet RSets");
3251   collection_set_iterate(&cl);
3252 }
3253 
3254 void G1CollectedHeap::print_all_rsets() {
3255   PrintRSetsClosure cl("Printing All RSets");;
3256   heap_region_iterate(&cl);
3257 }
3258 #endif // PRODUCT
3259 
3260 G1CollectedHeap* G1CollectedHeap::heap() {
3261   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3262          "not a garbage-first heap");
3263   return _g1h;
3264 }
3265 
3266 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3267   // always_do_update_barrier = false;
3268   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3269   // Call allocation profiler
3270   AllocationProfiler::iterate_since_last_gc();
3271   // Fill TLAB's and such
3272   ensure_parsability(true);
3273 }
3274 
3275 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3276   // FIXME: what is this about?
3277   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3278   // is set.
3279   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3280                         "derived pointer present"));
3281   // always_do_update_barrier = true;
3282 
3283   // We have just completed a GC. Update the soft reference
3284   // policy with the new heap occupancy
3285   Universe::update_heap_info_at_gc();
3286 }
3287 
3288 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3289                                                unsigned int gc_count_before,
3290                                                bool* succeeded) {
3291   assert_heap_not_locked_and_not_at_safepoint();
3292   g1_policy()->record_stop_world_start();
3293   VM_G1IncCollectionPause op(gc_count_before,
3294                              word_size,
3295                              false, /* should_initiate_conc_mark */
3296                              g1_policy()->max_pause_time_ms(),
3297                              GCCause::_g1_inc_collection_pause);
3298   VMThread::execute(&op);
3299 
3300   HeapWord* result = op.result();
3301   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3302   assert(result == NULL || ret_succeeded,
3303          "the result should be NULL if the VM did not succeed");
3304   *succeeded = ret_succeeded;
3305 
3306   assert_heap_not_locked();
3307   return result;
3308 }
3309 
3310 void
3311 G1CollectedHeap::doConcurrentMark() {
3312   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3313   if (!_cmThread->in_progress()) {
3314     _cmThread->set_started();
3315     CGC_lock->notify();
3316   }
3317 }
3318 
3319 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3320                                                        bool young) {
3321   return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3322 }
3323 
3324 void G1CollectedHeap::check_if_region_is_too_expensive(double
3325                                                            predicted_time_ms) {
3326   _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3327 }
3328 
3329 size_t G1CollectedHeap::pending_card_num() {
3330   size_t extra_cards = 0;
3331   JavaThread *curr = Threads::first();
3332   while (curr != NULL) {
3333     DirtyCardQueue& dcq = curr->dirty_card_queue();
3334     extra_cards += dcq.size();
3335     curr = curr->next();
3336   }
3337   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3338   size_t buffer_size = dcqs.buffer_size();
3339   size_t buffer_num = dcqs.completed_buffers_num();
3340   return buffer_size * buffer_num + extra_cards;
3341 }
3342 
3343 size_t G1CollectedHeap::max_pending_card_num() {
3344   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3345   size_t buffer_size = dcqs.buffer_size();
3346   size_t buffer_num  = dcqs.completed_buffers_num();
3347   int thread_num  = Threads::number_of_threads();
3348   return (buffer_num + thread_num) * buffer_size;
3349 }
3350 
3351 size_t G1CollectedHeap::cards_scanned() {
3352   return g1_rem_set()->cardsScanned();
3353 }
3354 
3355 void
3356 G1CollectedHeap::setup_surviving_young_words() {
3357   guarantee( _surviving_young_words == NULL, "pre-condition" );
3358   size_t array_length = g1_policy()->young_cset_region_length();
3359   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3360   if (_surviving_young_words == NULL) {
3361     vm_exit_out_of_memory(sizeof(size_t) * array_length,
3362                           "Not enough space for young surv words summary.");
3363   }
3364   memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3365 #ifdef ASSERT
3366   for (size_t i = 0;  i < array_length; ++i) {
3367     assert( _surviving_young_words[i] == 0, "memset above" );
3368   }
3369 #endif // !ASSERT
3370 }
3371 
3372 void
3373 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3374   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3375   size_t array_length = g1_policy()->young_cset_region_length();
3376   for (size_t i = 0; i < array_length; ++i)
3377     _surviving_young_words[i] += surv_young_words[i];
3378 }
3379 
3380 void
3381 G1CollectedHeap::cleanup_surviving_young_words() {
3382   guarantee( _surviving_young_words != NULL, "pre-condition" );
3383   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3384   _surviving_young_words = NULL;
3385 }
3386 
3387 #ifdef ASSERT
3388 class VerifyCSetClosure: public HeapRegionClosure {
3389 public:
3390   bool doHeapRegion(HeapRegion* hr) {
3391     // Here we check that the CSet region's RSet is ready for parallel
3392     // iteration. The fields that we'll verify are only manipulated
3393     // when the region is part of a CSet and is collected. Afterwards,
3394     // we reset these fields when we clear the region's RSet (when the
3395     // region is freed) so they are ready when the region is
3396     // re-allocated. The only exception to this is if there's an
3397     // evacuation failure and instead of freeing the region we leave
3398     // it in the heap. In that case, we reset these fields during
3399     // evacuation failure handling.
3400     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3401 
3402     // Here's a good place to add any other checks we'd like to
3403     // perform on CSet regions.
3404     return false;
3405   }
3406 };
3407 #endif // ASSERT
3408 
3409 #if TASKQUEUE_STATS
3410 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3411   st->print_raw_cr("GC Task Stats");
3412   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3413   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3414 }
3415 
3416 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3417   print_taskqueue_stats_hdr(st);
3418 
3419   TaskQueueStats totals;
3420   const int n = workers() != NULL ? workers()->total_workers() : 1;
3421   for (int i = 0; i < n; ++i) {
3422     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3423     totals += task_queue(i)->stats;
3424   }
3425   st->print_raw("tot "); totals.print(st); st->cr();
3426 
3427   DEBUG_ONLY(totals.verify());
3428 }
3429 
3430 void G1CollectedHeap::reset_taskqueue_stats() {
3431   const int n = workers() != NULL ? workers()->total_workers() : 1;
3432   for (int i = 0; i < n; ++i) {
3433     task_queue(i)->stats.reset();
3434   }
3435 }
3436 #endif // TASKQUEUE_STATS
3437 
3438 bool
3439 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3440   assert_at_safepoint(true /* should_be_vm_thread */);
3441   guarantee(!is_gc_active(), "collection is not reentrant");
3442 
3443   if (GC_locker::check_active_before_gc()) {
3444     return false;
3445   }
3446 
3447   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3448   ResourceMark rm;
3449 
3450   if (PrintHeapAtGC) {
3451     Universe::print_heap_before_gc();
3452   }
3453 
3454   HRSPhaseSetter x(HRSPhaseEvacuation);
3455   verify_region_sets_optional();
3456   verify_dirty_young_regions();
3457 
3458   {
3459     // This call will decide whether this pause is an initial-mark
3460     // pause. If it is, during_initial_mark_pause() will return true
3461     // for the duration of this pause.
3462     g1_policy()->decide_on_conc_mark_initiation();
3463 
3464     // We do not allow initial-mark to be piggy-backed on a
3465     // partially-young GC.
3466     assert(!g1_policy()->during_initial_mark_pause() ||
3467             g1_policy()->full_young_gcs(), "sanity");
3468 
3469     // We also do not allow partially-young GCs during marking.
3470     assert(!mark_in_progress() || g1_policy()->full_young_gcs(), "sanity");
3471 
3472     char verbose_str[128];
3473     sprintf(verbose_str, "GC pause ");
3474     if (g1_policy()->full_young_gcs()) {
3475       strcat(verbose_str, "(young)");
3476     } else {
3477       strcat(verbose_str, "(partial)");
3478     }
3479     if (g1_policy()->during_initial_mark_pause()) {
3480       strcat(verbose_str, " (initial-mark)");
3481       // We are about to start a marking cycle, so we increment the
3482       // full collection counter.
3483       increment_total_full_collections();
3484     }
3485 
3486     // if PrintGCDetails is on, we'll print long statistics information
3487     // in the collector policy code, so let's not print this as the output
3488     // is messy if we do.
3489     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3490     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3491     TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3492 
3493     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3494     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3495 
3496     // If the secondary_free_list is not empty, append it to the
3497     // free_list. No need to wait for the cleanup operation to finish;
3498     // the region allocation code will check the secondary_free_list
3499     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3500     // set, skip this step so that the region allocation code has to
3501     // get entries from the secondary_free_list.
3502     if (!G1StressConcRegionFreeing) {
3503       append_secondary_free_list_if_not_empty_with_lock();
3504     }
3505 
3506     assert(check_young_list_well_formed(),
3507       "young list should be well formed");
3508 
3509     // Don't dynamically change the number of GC threads this early.  A value of
3510     // 0 is used to indicate serial work.  When parallel work is done,
3511     // it will be set.
3512 
3513     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3514       IsGCActiveMark x;
3515 
3516       gc_prologue(false);
3517       increment_total_collections(false /* full gc */);
3518       increment_gc_time_stamp();
3519 
3520       if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3521         HandleMark hm;  // Discard invalid handles created during verification
3522         gclog_or_tty->print(" VerifyBeforeGC:");
3523         prepare_for_verify();
3524         Universe::verify(/* allow dirty */ false,
3525                          /* silent      */ false,
3526                          /* option      */ VerifyOption_G1UsePrevMarking);
3527 
3528       }
3529 
3530       COMPILER2_PRESENT(DerivedPointerTable::clear());
3531 
3532       // Please see comment in g1CollectedHeap.hpp and
3533       // G1CollectedHeap::ref_processing_init() to see how
3534       // reference processing currently works in G1.
3535 
3536       // Enable discovery in the STW reference processor
3537       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3538                                             true /*verify_no_refs*/);
3539 
3540       {
3541         // We want to temporarily turn off discovery by the
3542         // CM ref processor, if necessary, and turn it back on
3543         // on again later if we do. Using a scoped
3544         // NoRefDiscovery object will do this.
3545         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3546 
3547         // Forget the current alloc region (we might even choose it to be part
3548         // of the collection set!).
3549         release_mutator_alloc_region();
3550 
3551         // We should call this after we retire the mutator alloc
3552         // region(s) so that all the ALLOC / RETIRE events are generated
3553         // before the start GC event.
3554         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3555 
3556         // The elapsed time induced by the start time below deliberately elides
3557         // the possible verification above.
3558         double start_time_sec = os::elapsedTime();
3559         size_t start_used_bytes = used();
3560 
3561 #if YOUNG_LIST_VERBOSE
3562         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3563         _young_list->print();
3564         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3565 #endif // YOUNG_LIST_VERBOSE
3566 
3567         g1_policy()->record_collection_pause_start(start_time_sec,
3568                                                    start_used_bytes);
3569 
3570 #if YOUNG_LIST_VERBOSE
3571         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3572         _young_list->print();
3573 #endif // YOUNG_LIST_VERBOSE
3574 
3575         if (g1_policy()->during_initial_mark_pause()) {
3576           concurrent_mark()->checkpointRootsInitialPre();
3577         }
3578         perm_gen()->save_marks();
3579 
3580         // We must do this before any possible evacuation that should propagate
3581         // marks.
3582         if (mark_in_progress()) {
3583           double start_time_sec = os::elapsedTime();
3584 
3585           _cm->drainAllSATBBuffers();
3586           double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3587           g1_policy()->record_satb_drain_time(finish_mark_ms);
3588         }
3589         // Record the number of elements currently on the mark stack, so we
3590         // only iterate over these.  (Since evacuation may add to the mark
3591         // stack, doing more exposes race conditions.)  If no mark is in
3592         // progress, this will be zero.
3593         _cm->set_oops_do_bound();
3594 
3595         if (mark_in_progress()) {
3596           concurrent_mark()->newCSet();
3597         }
3598 
3599 #if YOUNG_LIST_VERBOSE
3600         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3601         _young_list->print();
3602         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3603 #endif // YOUNG_LIST_VERBOSE
3604 
3605         g1_policy()->choose_collection_set(target_pause_time_ms);
3606 
3607         if (_hr_printer.is_active()) {
3608           HeapRegion* hr = g1_policy()->collection_set();
3609           while (hr != NULL) {
3610             G1HRPrinter::RegionType type;
3611             if (!hr->is_young()) {
3612               type = G1HRPrinter::Old;
3613             } else if (hr->is_survivor()) {
3614               type = G1HRPrinter::Survivor;
3615             } else {
3616               type = G1HRPrinter::Eden;
3617             }
3618             _hr_printer.cset(hr);
3619             hr = hr->next_in_collection_set();
3620           }
3621         }
3622 
3623         // We have chosen the complete collection set. If marking is
3624         // active then, we clear the region fields of any of the
3625         // concurrent marking tasks whose region fields point into
3626         // the collection set as these values will become stale. This
3627         // will cause the owning marking threads to claim a new region
3628         // when marking restarts.
3629         if (mark_in_progress()) {
3630           concurrent_mark()->reset_active_task_region_fields_in_cset();
3631         }
3632 
3633 #ifdef ASSERT
3634         VerifyCSetClosure cl;
3635         collection_set_iterate(&cl);
3636 #endif // ASSERT
3637 
3638         setup_surviving_young_words();
3639 
3640         // Initialize the GC alloc regions.
3641         init_gc_alloc_regions();
3642 
3643         // Actually do the work...
3644         evacuate_collection_set();
3645 
3646         free_collection_set(g1_policy()->collection_set());
3647         g1_policy()->clear_collection_set();
3648 
3649         cleanup_surviving_young_words();
3650 
3651         // Start a new incremental collection set for the next pause.
3652         g1_policy()->start_incremental_cset_building();
3653 
3654         // Clear the _cset_fast_test bitmap in anticipation of adding
3655         // regions to the incremental collection set for the next
3656         // evacuation pause.
3657         clear_cset_fast_test();
3658 
3659         _young_list->reset_sampled_info();
3660 
3661         // Don't check the whole heap at this point as the
3662         // GC alloc regions from this pause have been tagged
3663         // as survivors and moved on to the survivor list.
3664         // Survivor regions will fail the !is_young() check.
3665         assert(check_young_list_empty(false /* check_heap */),
3666           "young list should be empty");
3667 
3668 #if YOUNG_LIST_VERBOSE
3669         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3670         _young_list->print();
3671 #endif // YOUNG_LIST_VERBOSE
3672 
3673         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3674                                             _young_list->first_survivor_region(),
3675                                             _young_list->last_survivor_region());
3676 
3677         _young_list->reset_auxilary_lists();
3678 
3679         if (evacuation_failed()) {
3680           _summary_bytes_used = recalculate_used();
3681         } else {
3682           // The "used" of the the collection set have already been subtracted
3683           // when they were freed.  Add in the bytes evacuated.
3684           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3685         }
3686 
3687         if (g1_policy()->during_initial_mark_pause()) {
3688           concurrent_mark()->checkpointRootsInitialPost();
3689           set_marking_started();
3690           // CAUTION: after the doConcurrentMark() call below,
3691           // the concurrent marking thread(s) could be running
3692           // concurrently with us. Make sure that anything after
3693           // this point does not assume that we are the only GC thread
3694           // running. Note: of course, the actual marking work will
3695           // not start until the safepoint itself is released in
3696           // ConcurrentGCThread::safepoint_desynchronize().
3697           doConcurrentMark();
3698         }
3699 
3700         allocate_dummy_regions();
3701 
3702 #if YOUNG_LIST_VERBOSE
3703         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3704         _young_list->print();
3705         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3706 #endif // YOUNG_LIST_VERBOSE
3707 
3708         init_mutator_alloc_region();
3709 
3710         {
3711           size_t expand_bytes = g1_policy()->expansion_amount();
3712           if (expand_bytes > 0) {
3713             size_t bytes_before = capacity();
3714             if (!expand(expand_bytes)) {
3715               // We failed to expand the heap so let's verify that
3716               // committed/uncommitted amount match the backing store
3717               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3718               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3719             }
3720           }
3721         }
3722 
3723         double end_time_sec = os::elapsedTime();
3724         double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3725         g1_policy()->record_pause_time_ms(pause_time_ms);
3726         int active_gc_threads = workers()->active_workers();
3727         g1_policy()->record_collection_pause_end(active_gc_threads);
3728 
3729         MemoryService::track_memory_usage();
3730 
3731         // In prepare_for_verify() below we'll need to scan the deferred
3732         // update buffers to bring the RSets up-to-date if
3733         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3734         // the update buffers we'll probably need to scan cards on the
3735         // regions we just allocated to (i.e., the GC alloc
3736         // regions). However, during the last GC we called
3737         // set_saved_mark() on all the GC alloc regions, so card
3738         // scanning might skip the [saved_mark_word()...top()] area of
3739         // those regions (i.e., the area we allocated objects into
3740         // during the last GC). But it shouldn't. Given that
3741         // saved_mark_word() is conditional on whether the GC time stamp
3742         // on the region is current or not, by incrementing the GC time
3743         // stamp here we invalidate all the GC time stamps on all the
3744         // regions and saved_mark_word() will simply return top() for
3745         // all the regions. This is a nicer way of ensuring this rather
3746         // than iterating over the regions and fixing them. In fact, the
3747         // GC time stamp increment here also ensures that
3748         // saved_mark_word() will return top() between pauses, i.e.,
3749         // during concurrent refinement. So we don't need the
3750         // is_gc_active() check to decided which top to use when
3751         // scanning cards (see CR 7039627).
3752         increment_gc_time_stamp();
3753 
3754         if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3755           HandleMark hm;  // Discard invalid handles created during verification
3756           gclog_or_tty->print(" VerifyAfterGC:");
3757           prepare_for_verify();
3758           Universe::verify(/* allow dirty */ true,
3759                            /* silent      */ false,
3760                            /* option      */ VerifyOption_G1UsePrevMarking);
3761         }
3762 
3763         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3764         ref_processor_stw()->verify_no_references_recorded();
3765 
3766         // CM reference discovery will be re-enabled if necessary.
3767       }
3768 
3769       {
3770         size_t expand_bytes = g1_policy()->expansion_amount();
3771         if (expand_bytes > 0) {
3772           size_t bytes_before = capacity();
3773           // No need for an ergo verbose message here,
3774           // expansion_amount() does this when it returns a value > 0.
3775           if (!expand(expand_bytes)) {
3776             // We failed to expand the heap so let's verify that
3777             // committed/uncommitted amount match the backing store
3778             assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3779             assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3780           }
3781         }
3782       }
3783 
3784       // We should do this after we potentially expand the heap so
3785       // that all the COMMIT events are generated before the end GC
3786       // event, and after we retire the GC alloc regions so that all
3787       // RETIRE events are generated before the end GC event.
3788       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3789 
3790       // We have to do this after we decide whether to expand the heap or not.
3791       g1_policy()->print_heap_transition();
3792 
3793       if (mark_in_progress()) {
3794         concurrent_mark()->update_g1_committed();
3795       }
3796 
3797 #ifdef TRACESPINNING
3798       ParallelTaskTerminator::print_termination_counts();
3799 #endif
3800 
3801       gc_epilogue(false);
3802     }
3803 
3804     if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3805       gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3806       print_tracing_info();
3807       vm_exit(-1);
3808     }
3809   }
3810 
3811   _hrs.verify_optional();
3812   verify_region_sets_optional();
3813 
3814   TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3815   TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3816 
3817   if (PrintHeapAtGC) {
3818     Universe::print_heap_after_gc();
3819   }
3820   g1mm()->update_sizes();
3821 
3822   if (G1SummarizeRSetStats &&
3823       (G1SummarizeRSetStatsPeriod > 0) &&
3824       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3825     g1_rem_set()->print_summary_info();
3826   }
3827 
3828   return true;
3829 }
3830 
3831 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3832 {
3833   size_t gclab_word_size;
3834   switch (purpose) {
3835     case GCAllocForSurvived:
3836       gclab_word_size = YoungPLABSize;
3837       break;
3838     case GCAllocForTenured:
3839       gclab_word_size = OldPLABSize;
3840       break;
3841     default:
3842       assert(false, "unknown GCAllocPurpose");
3843       gclab_word_size = OldPLABSize;
3844       break;
3845   }
3846   return gclab_word_size;
3847 }
3848 
3849 void G1CollectedHeap::init_mutator_alloc_region() {
3850   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3851   _mutator_alloc_region.init();
3852 }
3853 
3854 void G1CollectedHeap::release_mutator_alloc_region() {
3855   _mutator_alloc_region.release();
3856   assert(_mutator_alloc_region.get() == NULL, "post-condition");
3857 }
3858 
3859 void G1CollectedHeap::init_gc_alloc_regions() {
3860   assert_at_safepoint(true /* should_be_vm_thread */);
3861 
3862   _survivor_gc_alloc_region.init();
3863   _old_gc_alloc_region.init();
3864   HeapRegion* retained_region = _retained_old_gc_alloc_region;
3865   _retained_old_gc_alloc_region = NULL;
3866 
3867   // We will discard the current GC alloc region if:
3868   // a) it's in the collection set (it can happen!),
3869   // b) it's already full (no point in using it),
3870   // c) it's empty (this means that it was emptied during
3871   // a cleanup and it should be on the free list now), or
3872   // d) it's humongous (this means that it was emptied
3873   // during a cleanup and was added to the free list, but
3874   // has been subseqently used to allocate a humongous
3875   // object that may be less than the region size).
3876   if (retained_region != NULL &&
3877       !retained_region->in_collection_set() &&
3878       !(retained_region->top() == retained_region->end()) &&
3879       !retained_region->is_empty() &&
3880       !retained_region->isHumongous()) {
3881     retained_region->set_saved_mark();
3882     // The retained region was added to the old region set when it was
3883     // retired. We have to remove it now, since we don't allow regions
3884     // we allocate to in the region sets. We'll re-add it later, when
3885     // it's retired again.
3886     _old_set.remove(retained_region);
3887     _old_gc_alloc_region.set(retained_region);
3888     _hr_printer.reuse(retained_region);
3889   }
3890 }
3891 
3892 void G1CollectedHeap::release_gc_alloc_regions() {
3893   _survivor_gc_alloc_region.release();
3894   // If we have an old GC alloc region to release, we'll save it in
3895   // _retained_old_gc_alloc_region. If we don't
3896   // _retained_old_gc_alloc_region will become NULL. This is what we
3897   // want either way so no reason to check explicitly for either
3898   // condition.
3899   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
3900 }
3901 
3902 void G1CollectedHeap::abandon_gc_alloc_regions() {
3903   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
3904   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
3905   _retained_old_gc_alloc_region = NULL;
3906 }
3907 
3908 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3909   _drain_in_progress = false;
3910   set_evac_failure_closure(cl);
3911   _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3912 }
3913 
3914 void G1CollectedHeap::finalize_for_evac_failure() {
3915   assert(_evac_failure_scan_stack != NULL &&
3916          _evac_failure_scan_stack->length() == 0,
3917          "Postcondition");
3918   assert(!_drain_in_progress, "Postcondition");
3919   delete _evac_failure_scan_stack;
3920   _evac_failure_scan_stack = NULL;
3921 }
3922 
3923 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3924 private:
3925   G1CollectedHeap* _g1;
3926   DirtyCardQueue *_dcq;
3927   CardTableModRefBS* _ct_bs;
3928 
3929 public:
3930   UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3931     _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3932 
3933   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3934   virtual void do_oop(      oop* p) { do_oop_work(p); }
3935   template <class T> void do_oop_work(T* p) {
3936     assert(_from->is_in_reserved(p), "paranoia");
3937     if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3938         !_from->is_survivor()) {
3939       size_t card_index = _ct_bs->index_for(p);
3940       if (_ct_bs->mark_card_deferred(card_index)) {
3941         _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3942       }
3943     }
3944   }
3945 };
3946 
3947 class RemoveSelfPointerClosure: public ObjectClosure {
3948 private:
3949   G1CollectedHeap* _g1;
3950   ConcurrentMark* _cm;
3951   HeapRegion* _hr;
3952   size_t _prev_marked_bytes;
3953   size_t _next_marked_bytes;
3954   OopsInHeapRegionClosure *_cl;
3955 public:
3956   RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
3957                            OopsInHeapRegionClosure* cl) :
3958     _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()),  _prev_marked_bytes(0),
3959     _next_marked_bytes(0), _cl(cl) {}
3960 
3961   size_t prev_marked_bytes() { return _prev_marked_bytes; }
3962   size_t next_marked_bytes() { return _next_marked_bytes; }
3963 
3964   // <original comment>
3965   // The original idea here was to coalesce evacuated and dead objects.
3966   // However that caused complications with the block offset table (BOT).
3967   // In particular if there were two TLABs, one of them partially refined.
3968   // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3969   // The BOT entries of the unrefined part of TLAB_2 point to the start
3970   // of TLAB_2. If the last object of the TLAB_1 and the first object
3971   // of TLAB_2 are coalesced, then the cards of the unrefined part
3972   // would point into middle of the filler object.
3973   // The current approach is to not coalesce and leave the BOT contents intact.
3974   // </original comment>
3975   //
3976   // We now reset the BOT when we start the object iteration over the
3977   // region and refine its entries for every object we come across. So
3978   // the above comment is not really relevant and we should be able
3979   // to coalesce dead objects if we want to.
3980   void do_object(oop obj) {
3981     HeapWord* obj_addr = (HeapWord*) obj;
3982     assert(_hr->is_in(obj_addr), "sanity");
3983     size_t obj_size = obj->size();
3984     _hr->update_bot_for_object(obj_addr, obj_size);
3985     if (obj->is_forwarded() && obj->forwardee() == obj) {
3986       // The object failed to move.
3987       assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3988       _cm->markPrev(obj);
3989       assert(_cm->isPrevMarked(obj), "Should be marked!");
3990       _prev_marked_bytes += (obj_size * HeapWordSize);
3991       if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3992         _cm->markAndGrayObjectIfNecessary(obj);
3993       }
3994       obj->set_mark(markOopDesc::prototype());
3995       // While we were processing RSet buffers during the
3996       // collection, we actually didn't scan any cards on the
3997       // collection set, since we didn't want to update remebered
3998       // sets with entries that point into the collection set, given
3999       // that live objects fromthe collection set are about to move
4000       // and such entries will be stale very soon. This change also
4001       // dealt with a reliability issue which involved scanning a
4002       // card in the collection set and coming across an array that
4003       // was being chunked and looking malformed. The problem is
4004       // that, if evacuation fails, we might have remembered set
4005       // entries missing given that we skipped cards on the
4006       // collection set. So, we'll recreate such entries now.
4007       obj->oop_iterate(_cl);
4008       assert(_cm->isPrevMarked(obj), "Should be marked!");
4009     } else {
4010       // The object has been either evacuated or is dead. Fill it with a
4011       // dummy object.
4012       MemRegion mr((HeapWord*)obj, obj_size);
4013       CollectedHeap::fill_with_object(mr);
4014       _cm->clearRangeBothMaps(mr);
4015     }
4016   }
4017 };
4018 
4019 void G1CollectedHeap::remove_self_forwarding_pointers() {
4020   UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
4021   DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
4022   UpdateRSetDeferred deferred_update(_g1h, &dcq);
4023   OopsInHeapRegionClosure *cl;
4024   if (G1DeferredRSUpdate) {
4025     cl = &deferred_update;
4026   } else {
4027     cl = &immediate_update;
4028   }
4029   HeapRegion* cur = g1_policy()->collection_set();
4030   while (cur != NULL) {
4031     assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4032     assert(!cur->isHumongous(), "sanity");
4033 
4034     if (cur->evacuation_failed()) {
4035       assert(cur->in_collection_set(), "bad CS");
4036       RemoveSelfPointerClosure rspc(_g1h, cur, cl);
4037 
4038       // In the common case we make sure that this is done when the
4039       // region is freed so that it is "ready-to-go" when it's
4040       // re-allocated. However, when evacuation failure happens, a
4041       // region will remain in the heap and might ultimately be added
4042       // to a CSet in the future. So we have to be careful here and
4043       // make sure the region's RSet is ready for parallel iteration
4044       // whenever this might be required in the future.
4045       cur->rem_set()->reset_for_par_iteration();
4046       cur->reset_bot();
4047       cl->set_region(cur);
4048       cur->object_iterate(&rspc);
4049 
4050       // A number of manipulations to make the TAMS be the current top,
4051       // and the marked bytes be the ones observed in the iteration.
4052       if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
4053         // The comments below are the postconditions achieved by the
4054         // calls.  Note especially the last such condition, which says that
4055         // the count of marked bytes has been properly restored.
4056         cur->note_start_of_marking(false);
4057         // _next_top_at_mark_start == top, _next_marked_bytes == 0
4058         cur->add_to_marked_bytes(rspc.prev_marked_bytes());
4059         // _next_marked_bytes == prev_marked_bytes.
4060         cur->note_end_of_marking();
4061         // _prev_top_at_mark_start == top(),
4062         // _prev_marked_bytes == prev_marked_bytes
4063       }
4064       // If there is no mark in progress, we modified the _next variables
4065       // above needlessly, but harmlessly.
4066       if (_g1h->mark_in_progress()) {
4067         cur->note_start_of_marking(false);
4068         // _next_top_at_mark_start == top, _next_marked_bytes == 0
4069         // _next_marked_bytes == next_marked_bytes.
4070       }
4071     }
4072     cur = cur->next_in_collection_set();
4073   }
4074   assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4075 
4076   // Now restore saved marks, if any.
4077   if (_objs_with_preserved_marks != NULL) {
4078     assert(_preserved_marks_of_objs != NULL, "Both or none.");
4079     guarantee(_objs_with_preserved_marks->length() ==
4080               _preserved_marks_of_objs->length(), "Both or none.");
4081     for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
4082       oop obj   = _objs_with_preserved_marks->at(i);
4083       markOop m = _preserved_marks_of_objs->at(i);
4084       obj->set_mark(m);
4085     }
4086     // Delete the preserved marks growable arrays (allocated on the C heap).
4087     delete _objs_with_preserved_marks;
4088     delete _preserved_marks_of_objs;
4089     _objs_with_preserved_marks = NULL;
4090     _preserved_marks_of_objs = NULL;
4091   }
4092 }
4093 
4094 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4095   _evac_failure_scan_stack->push(obj);
4096 }
4097 
4098 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4099   assert(_evac_failure_scan_stack != NULL, "precondition");
4100 
4101   while (_evac_failure_scan_stack->length() > 0) {
4102      oop obj = _evac_failure_scan_stack->pop();
4103      _evac_failure_closure->set_region(heap_region_containing(obj));
4104      obj->oop_iterate_backwards(_evac_failure_closure);
4105   }
4106 }
4107 
4108 oop
4109 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4110                                                oop old,
4111                                                bool should_mark_root) {
4112   assert(obj_in_cs(old),
4113          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4114                  (HeapWord*) old));
4115   markOop m = old->mark();
4116   oop forward_ptr = old->forward_to_atomic(old);
4117   if (forward_ptr == NULL) {
4118     // Forward-to-self succeeded.
4119 
4120     // should_mark_root will be true when this routine is called
4121     // from a root scanning closure during an initial mark pause.
4122     // In this case the thread that succeeds in self-forwarding the
4123     // object is also responsible for marking the object.
4124     if (should_mark_root) {
4125       assert(!oopDesc::is_null(old), "shouldn't be");
4126       _cm->grayRoot(old);
4127     }
4128 
4129     if (_evac_failure_closure != cl) {
4130       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4131       assert(!_drain_in_progress,
4132              "Should only be true while someone holds the lock.");
4133       // Set the global evac-failure closure to the current thread's.
4134       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4135       set_evac_failure_closure(cl);
4136       // Now do the common part.
4137       handle_evacuation_failure_common(old, m);
4138       // Reset to NULL.
4139       set_evac_failure_closure(NULL);
4140     } else {
4141       // The lock is already held, and this is recursive.
4142       assert(_drain_in_progress, "This should only be the recursive case.");
4143       handle_evacuation_failure_common(old, m);
4144     }
4145     return old;
4146   } else {
4147     // Forward-to-self failed. Either someone else managed to allocate
4148     // space for this object (old != forward_ptr) or they beat us in
4149     // self-forwarding it (old == forward_ptr).
4150     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4151            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4152                    "should not be in the CSet",
4153                    (HeapWord*) old, (HeapWord*) forward_ptr));
4154     return forward_ptr;
4155   }
4156 }
4157 
4158 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4159   set_evacuation_failed(true);
4160 
4161   preserve_mark_if_necessary(old, m);
4162 
4163   HeapRegion* r = heap_region_containing(old);
4164   if (!r->evacuation_failed()) {
4165     r->set_evacuation_failed(true);
4166     _hr_printer.evac_failure(r);
4167   }
4168 
4169   push_on_evac_failure_scan_stack(old);
4170 
4171   if (!_drain_in_progress) {
4172     // prevent recursion in copy_to_survivor_space()
4173     _drain_in_progress = true;
4174     drain_evac_failure_scan_stack();
4175     _drain_in_progress = false;
4176   }
4177 }
4178 
4179 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4180   assert(evacuation_failed(), "Oversaving!");
4181   // We want to call the "for_promotion_failure" version only in the
4182   // case of a promotion failure.
4183   if (m->must_be_preserved_for_promotion_failure(obj)) {
4184     if (_objs_with_preserved_marks == NULL) {
4185       assert(_preserved_marks_of_objs == NULL, "Both or none.");
4186       _objs_with_preserved_marks =
4187         new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4188       _preserved_marks_of_objs =
4189         new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4190     }
4191     _objs_with_preserved_marks->push(obj);
4192     _preserved_marks_of_objs->push(m);
4193   }
4194 }
4195 
4196 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4197                                                   size_t word_size) {
4198   if (purpose == GCAllocForSurvived) {
4199     HeapWord* result = survivor_attempt_allocation(word_size);
4200     if (result != NULL) {
4201       return result;
4202     } else {
4203       // Let's try to allocate in the old gen in case we can fit the
4204       // object there.
4205       return old_attempt_allocation(word_size);
4206     }
4207   } else {
4208     assert(purpose ==  GCAllocForTenured, "sanity");
4209     HeapWord* result = old_attempt_allocation(word_size);
4210     if (result != NULL) {
4211       return result;
4212     } else {
4213       // Let's try to allocate in the survivors in case we can fit the
4214       // object there.
4215       return survivor_attempt_allocation(word_size);
4216     }
4217   }
4218 
4219   ShouldNotReachHere();
4220   // Trying to keep some compilers happy.
4221   return NULL;
4222 }
4223 
4224 #ifndef PRODUCT
4225 bool GCLabBitMapClosure::do_bit(size_t offset) {
4226   HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4227   guarantee(_cm->isMarked(oop(addr)), "it should be!");
4228   return true;
4229 }
4230 #endif // PRODUCT
4231 
4232 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4233   ParGCAllocBuffer(gclab_word_size),
4234   _should_mark_objects(false),
4235   _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
4236   _retired(false)
4237 {
4238   //_should_mark_objects is set to true when G1ParCopyHelper needs to
4239   // mark the forwarded location of an evacuated object.
4240   // We set _should_mark_objects to true if marking is active, i.e. when we
4241   // need to propagate a mark, or during an initial mark pause, i.e. when we
4242   // need to mark objects immediately reachable by the roots.
4243   if (G1CollectedHeap::heap()->mark_in_progress() ||
4244       G1CollectedHeap::heap()->g1_policy()->during_initial_mark_pause()) {
4245     _should_mark_objects = true;
4246   }
4247 }
4248 
4249 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4250   : _g1h(g1h),
4251     _refs(g1h->task_queue(queue_num)),
4252     _dcq(&g1h->dirty_card_queue_set()),
4253     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4254     _g1_rem(g1h->g1_rem_set()),
4255     _hash_seed(17), _queue_num(queue_num),
4256     _term_attempts(0),
4257     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4258     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4259     _age_table(false),
4260     _strong_roots_time(0), _term_time(0),
4261     _alloc_buffer_waste(0), _undo_waste(0)
4262 {
4263   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4264   // we "sacrifice" entry 0 to keep track of surviving bytes for
4265   // non-young regions (where the age is -1)
4266   // We also add a few elements at the beginning and at the end in
4267   // an attempt to eliminate cache contention
4268   size_t real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4269   size_t array_length = PADDING_ELEM_NUM +
4270                         real_length +
4271                         PADDING_ELEM_NUM;
4272   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4273   if (_surviving_young_words_base == NULL)
4274     vm_exit_out_of_memory(array_length * sizeof(size_t),
4275                           "Not enough space for young surv histo.");
4276   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4277   memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4278 
4279   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4280   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4281 
4282   _start = os::elapsedTime();
4283 }
4284 
4285 void
4286 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4287 {
4288   st->print_raw_cr("GC Termination Stats");
4289   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4290                    " ------waste (KiB)------");
4291   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4292                    "  total   alloc    undo");
4293   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4294                    " ------- ------- -------");
4295 }
4296 
4297 void
4298 G1ParScanThreadState::print_termination_stats(int i,
4299                                               outputStream* const st) const
4300 {
4301   const double elapsed_ms = elapsed_time() * 1000.0;
4302   const double s_roots_ms = strong_roots_time() * 1000.0;
4303   const double term_ms    = term_time() * 1000.0;
4304   st->print_cr("%3d %9.2f %9.2f %6.2f "
4305                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4306                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4307                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4308                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4309                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4310                alloc_buffer_waste() * HeapWordSize / K,
4311                undo_waste() * HeapWordSize / K);
4312 }
4313 
4314 #ifdef ASSERT
4315 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4316   assert(ref != NULL, "invariant");
4317   assert(UseCompressedOops, "sanity");
4318   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4319   oop p = oopDesc::load_decode_heap_oop(ref);
4320   assert(_g1h->is_in_g1_reserved(p),
4321          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4322   return true;
4323 }
4324 
4325 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4326   assert(ref != NULL, "invariant");
4327   if (has_partial_array_mask(ref)) {
4328     // Must be in the collection set--it's already been copied.
4329     oop p = clear_partial_array_mask(ref);
4330     assert(_g1h->obj_in_cs(p),
4331            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4332   } else {
4333     oop p = oopDesc::load_decode_heap_oop(ref);
4334     assert(_g1h->is_in_g1_reserved(p),
4335            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4336   }
4337   return true;
4338 }
4339 
4340 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4341   if (ref.is_narrow()) {
4342     return verify_ref((narrowOop*) ref);
4343   } else {
4344     return verify_ref((oop*) ref);
4345   }
4346 }
4347 #endif // ASSERT
4348 
4349 void G1ParScanThreadState::trim_queue() {
4350   assert(_evac_cl != NULL, "not set");
4351   assert(_evac_failure_cl != NULL, "not set");
4352   assert(_partial_scan_cl != NULL, "not set");
4353 
4354   StarTask ref;
4355   do {
4356     // Drain the overflow stack first, so other threads can steal.
4357     while (refs()->pop_overflow(ref)) {
4358       deal_with_reference(ref);
4359     }
4360 
4361     while (refs()->pop_local(ref)) {
4362       deal_with_reference(ref);
4363     }
4364   } while (!refs()->is_empty());
4365 }
4366 
4367 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4368   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4369   _par_scan_state(par_scan_state),
4370   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4371   _mark_in_progress(_g1->mark_in_progress()) { }
4372 
4373 template <class T> void G1ParCopyHelper::mark_object(T* p) {
4374   // This is called from do_oop_work for objects that are not
4375   // in the collection set. Objects in the collection set
4376   // are marked after they have been evacuated.
4377 
4378   T heap_oop = oopDesc::load_heap_oop(p);
4379   if (!oopDesc::is_null(heap_oop)) {
4380     oop obj = oopDesc::decode_heap_oop(heap_oop);
4381     HeapWord* addr = (HeapWord*)obj;
4382     if (_g1->is_in_g1_reserved(addr)) {
4383       _cm->grayRoot(oop(addr));
4384     }
4385   }
4386 }
4387 
4388 oop G1ParCopyHelper::copy_to_survivor_space(oop old, bool should_mark_root,
4389                                                      bool should_mark_copy) {
4390   size_t    word_sz = old->size();
4391   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4392   // +1 to make the -1 indexes valid...
4393   int       young_index = from_region->young_index_in_cset()+1;
4394   assert( (from_region->is_young() && young_index > 0) ||
4395           (!from_region->is_young() && young_index == 0), "invariant" );
4396   G1CollectorPolicy* g1p = _g1->g1_policy();
4397   markOop m = old->mark();
4398   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4399                                            : m->age();
4400   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4401                                                              word_sz);
4402   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4403   oop       obj     = oop(obj_ptr);
4404 
4405   if (obj_ptr == NULL) {
4406     // This will either forward-to-self, or detect that someone else has
4407     // installed a forwarding pointer.
4408     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4409     return _g1->handle_evacuation_failure_par(cl, old, should_mark_root);
4410   }
4411 
4412   // We're going to allocate linearly, so might as well prefetch ahead.
4413   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4414 
4415   oop forward_ptr = old->forward_to_atomic(obj);
4416   if (forward_ptr == NULL) {
4417     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4418     if (g1p->track_object_age(alloc_purpose)) {
4419       // We could simply do obj->incr_age(). However, this causes a
4420       // performance issue. obj->incr_age() will first check whether
4421       // the object has a displaced mark by checking its mark word;
4422       // getting the mark word from the new location of the object
4423       // stalls. So, given that we already have the mark word and we
4424       // are about to install it anyway, it's better to increase the
4425       // age on the mark word, when the object does not have a
4426       // displaced mark word. We're not expecting many objects to have
4427       // a displaced marked word, so that case is not optimized
4428       // further (it could be...) and we simply call obj->incr_age().
4429 
4430       if (m->has_displaced_mark_helper()) {
4431         // in this case, we have to install the mark word first,
4432         // otherwise obj looks to be forwarded (the old mark word,
4433         // which contains the forward pointer, was copied)
4434         obj->set_mark(m);
4435         obj->incr_age();
4436       } else {
4437         m = m->incr_age();
4438         obj->set_mark(m);
4439       }
4440       _par_scan_state->age_table()->add(obj, word_sz);
4441     } else {
4442       obj->set_mark(m);
4443     }
4444 
4445     // Mark the evacuated object or propagate "next" mark bit
4446     if (should_mark_copy) {
4447       if (!use_local_bitmaps ||
4448           !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4449         // if we couldn't mark it on the local bitmap (this happens when
4450         // the object was not allocated in the GCLab), we have to bite
4451         // the bullet and do the standard parallel mark
4452         _cm->markAndGrayObjectIfNecessary(obj);
4453       }
4454 
4455       if (_g1->isMarkedNext(old)) {
4456         // Unmark the object's old location so that marking
4457         // doesn't think the old object is alive.
4458         _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4459       }
4460     }
4461 
4462     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4463     surv_young_words[young_index] += word_sz;
4464 
4465     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4466       arrayOop(old)->set_length(0);
4467       oop* old_p = set_partial_array_mask(old);
4468       _par_scan_state->push_on_queue(old_p);
4469     } else {
4470       // No point in using the slower heap_region_containing() method,
4471       // given that we know obj is in the heap.
4472       _scanner->set_region(_g1->heap_region_containing_raw(obj));
4473       obj->oop_iterate_backwards(_scanner);
4474     }
4475   } else {
4476     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4477     obj = forward_ptr;
4478   }
4479   return obj;
4480 }
4481 
4482 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4483 template <class T>
4484 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4485 ::do_oop_work(T* p) {
4486   oop obj = oopDesc::load_decode_heap_oop(p);
4487   assert(barrier != G1BarrierRS || obj != NULL,
4488          "Precondition: G1BarrierRS implies obj is nonNull");
4489 
4490   // Marking:
4491   // If the object is in the collection set, then the thread
4492   // that copies the object should mark, or propagate the
4493   // mark to, the evacuated object.
4494   // If the object is not in the collection set then we
4495   // should call the mark_object() method depending on the
4496   // value of the template parameter do_mark_object (which will
4497   // be true for root scanning closures during an initial mark
4498   // pause).
4499   // The mark_object() method first checks whether the object
4500   // is marked and, if not, attempts to mark the object.
4501 
4502   // here the null check is implicit in the cset_fast_test() test
4503   if (_g1->in_cset_fast_test(obj)) {
4504     if (obj->is_forwarded()) {
4505       oopDesc::encode_store_heap_oop(p, obj->forwardee());
4506       // If we are a root scanning closure during an initial
4507       // mark pause (i.e. do_mark_object will be true) then
4508       // we also need to handle marking of roots in the
4509       // event of an evacuation failure. In the event of an
4510       // evacuation failure, the object is forwarded to itself
4511       // and not copied. For root-scanning closures, the
4512       // object would be marked after a successful self-forward
4513       // but an object could be pointed to by both a root and non
4514       // root location and be self-forwarded by a non-root-scanning
4515       // closure. Therefore we also have to attempt to mark the
4516       // self-forwarded root object here.
4517       if (do_mark_object && obj->forwardee() == obj) {
4518         mark_object(p);
4519       }
4520     } else {
4521       // During an initial mark pause, objects that are pointed to
4522       // by the roots need to be marked - even in the event of an
4523       // evacuation failure. We pass the template parameter
4524       // do_mark_object (which is true for root scanning closures
4525       // during an initial mark pause) to copy_to_survivor_space
4526       // which will pass it on to the evacuation failure handling
4527       // code. The thread that successfully self-forwards a root
4528       // object to itself is responsible for marking the object.
4529       bool should_mark_root = do_mark_object;
4530 
4531       // We need to mark the copied object if we're a root scanning
4532       // closure during an initial mark pause (i.e. do_mark_object
4533       // will be true), or the object is already marked and we need
4534       // to propagate the mark to the evacuated copy.
4535       bool should_mark_copy = do_mark_object ||
4536                               _during_initial_mark ||
4537                               (_mark_in_progress && !_g1->is_obj_ill(obj));
4538 
4539       oop copy_oop = copy_to_survivor_space(obj, should_mark_root,
4540                                                  should_mark_copy);
4541       oopDesc::encode_store_heap_oop(p, copy_oop);
4542     }
4543     // When scanning the RS, we only care about objs in CS.
4544     if (barrier == G1BarrierRS) {
4545       _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4546     }
4547   } else {
4548     // The object is not in collection set. If we're a root scanning
4549     // closure during an initial mark pause (i.e. do_mark_object will
4550     // be true) then attempt to mark the object.
4551     if (do_mark_object) {
4552       mark_object(p);
4553     }
4554   }
4555 
4556   if (barrier == G1BarrierEvac && obj != NULL) {
4557     _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4558   }
4559 
4560   if (do_gen_barrier && obj != NULL) {
4561     par_do_barrier(p);
4562   }
4563 }
4564 
4565 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4566 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4567 
4568 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4569   assert(has_partial_array_mask(p), "invariant");
4570   oop old = clear_partial_array_mask(p);
4571   assert(old->is_objArray(), "must be obj array");
4572   assert(old->is_forwarded(), "must be forwarded");
4573   assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4574 
4575   objArrayOop obj = objArrayOop(old->forwardee());
4576   assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4577   // Process ParGCArrayScanChunk elements now
4578   // and push the remainder back onto queue
4579   int start     = arrayOop(old)->length();
4580   int end       = obj->length();
4581   int remainder = end - start;
4582   assert(start <= end, "just checking");
4583   if (remainder > 2 * ParGCArrayScanChunk) {
4584     // Test above combines last partial chunk with a full chunk
4585     end = start + ParGCArrayScanChunk;
4586     arrayOop(old)->set_length(end);
4587     // Push remainder.
4588     oop* old_p = set_partial_array_mask(old);
4589     assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4590     _par_scan_state->push_on_queue(old_p);
4591   } else {
4592     // Restore length so that the heap remains parsable in
4593     // case of evacuation failure.
4594     arrayOop(old)->set_length(end);
4595   }
4596   _scanner.set_region(_g1->heap_region_containing_raw(obj));
4597   // process our set of indices (include header in first chunk)
4598   obj->oop_iterate_range(&_scanner, start, end);
4599 }
4600 
4601 class G1ParEvacuateFollowersClosure : public VoidClosure {
4602 protected:
4603   G1CollectedHeap*              _g1h;
4604   G1ParScanThreadState*         _par_scan_state;
4605   RefToScanQueueSet*            _queues;
4606   ParallelTaskTerminator*       _terminator;
4607 
4608   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4609   RefToScanQueueSet*      queues()         { return _queues; }
4610   ParallelTaskTerminator* terminator()     { return _terminator; }
4611 
4612 public:
4613   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4614                                 G1ParScanThreadState* par_scan_state,
4615                                 RefToScanQueueSet* queues,
4616                                 ParallelTaskTerminator* terminator)
4617     : _g1h(g1h), _par_scan_state(par_scan_state),
4618       _queues(queues), _terminator(terminator) {}
4619 
4620   void do_void();
4621 
4622 private:
4623   inline bool offer_termination();
4624 };
4625 
4626 bool G1ParEvacuateFollowersClosure::offer_termination() {
4627   G1ParScanThreadState* const pss = par_scan_state();
4628   pss->start_term_time();
4629   const bool res = terminator()->offer_termination();
4630   pss->end_term_time();
4631   return res;
4632 }
4633 
4634 void G1ParEvacuateFollowersClosure::do_void() {
4635   StarTask stolen_task;
4636   G1ParScanThreadState* const pss = par_scan_state();
4637   pss->trim_queue();
4638 
4639   do {
4640     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4641       assert(pss->verify_task(stolen_task), "sanity");
4642       if (stolen_task.is_narrow()) {
4643         pss->deal_with_reference((narrowOop*) stolen_task);
4644       } else {
4645         pss->deal_with_reference((oop*) stolen_task);
4646       }
4647 
4648       // We've just processed a reference and we might have made
4649       // available new entries on the queues. So we have to make sure
4650       // we drain the queues as necessary.
4651       pss->trim_queue();
4652     }
4653   } while (!offer_termination());
4654 
4655   pss->retire_alloc_buffers();
4656 }
4657 
4658 class G1ParTask : public AbstractGangTask {
4659 protected:
4660   G1CollectedHeap*       _g1h;
4661   RefToScanQueueSet      *_queues;
4662   ParallelTaskTerminator _terminator;
4663   int _n_workers;
4664 
4665   Mutex _stats_lock;
4666   Mutex* stats_lock() { return &_stats_lock; }
4667 
4668   size_t getNCards() {
4669     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4670       / G1BlockOffsetSharedArray::N_bytes;
4671   }
4672 
4673 public:
4674   G1ParTask(G1CollectedHeap* g1h,
4675             RefToScanQueueSet *task_queues)
4676     : AbstractGangTask("G1 collection"),
4677       _g1h(g1h),
4678       _queues(task_queues),
4679       _terminator(0, _queues),
4680       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4681   {}
4682 
4683   RefToScanQueueSet* queues() { return _queues; }
4684 
4685   RefToScanQueue *work_queue(int i) {
4686     return queues()->queue(i);
4687   }
4688 
4689   ParallelTaskTerminator* terminator() { return &_terminator; }
4690 
4691   virtual void set_for_termination(int active_workers) {
4692     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4693     // in the young space (_par_seq_tasks) in the G1 heap
4694     // for SequentialSubTasksDone.
4695     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4696     // both of which need setting by set_n_termination().
4697     _g1h->SharedHeap::set_n_termination(active_workers);
4698     _g1h->set_n_termination(active_workers);
4699     terminator()->reset_for_reuse(active_workers);
4700     _n_workers = active_workers;
4701   }
4702 
4703   void work(int i) {
4704     if (i >= _n_workers) return;  // no work needed this round
4705 
4706     double start_time_ms = os::elapsedTime() * 1000.0;
4707     _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4708 
4709     ResourceMark rm;
4710     HandleMark   hm;
4711 
4712     ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4713 
4714     G1ParScanThreadState            pss(_g1h, i);
4715     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
4716     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4717     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
4718 
4719     pss.set_evac_closure(&scan_evac_cl);
4720     pss.set_evac_failure_closure(&evac_failure_cl);
4721     pss.set_partial_scan_closure(&partial_scan_cl);
4722 
4723     G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4724     G1ParScanPermClosure           only_scan_perm_cl(_g1h, &pss, rp);
4725 
4726     G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4727     G1ParScanAndMarkPermClosure    scan_mark_perm_cl(_g1h, &pss, rp);
4728 
4729     OopClosure*                    scan_root_cl = &only_scan_root_cl;
4730     OopsInHeapRegionClosure*       scan_perm_cl = &only_scan_perm_cl;
4731 
4732     if (_g1h->g1_policy()->during_initial_mark_pause()) {
4733       // We also need to mark copied objects.
4734       scan_root_cl = &scan_mark_root_cl;
4735       scan_perm_cl = &scan_mark_perm_cl;
4736     }
4737 
4738     G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
4739 
4740     pss.start_strong_roots();
4741     _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4742                                   SharedHeap::SO_AllClasses,
4743                                   scan_root_cl,
4744                                   &push_heap_rs_cl,
4745                                   scan_perm_cl,
4746                                   i);
4747     pss.end_strong_roots();
4748 
4749     {
4750       double start = os::elapsedTime();
4751       G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4752       evac.do_void();
4753       double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4754       double term_ms = pss.term_time()*1000.0;
4755       _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4756       _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4757     }
4758     _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4759     _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4760 
4761     // Clean up any par-expanded rem sets.
4762     HeapRegionRemSet::par_cleanup();
4763 
4764     if (ParallelGCVerbose) {
4765       MutexLocker x(stats_lock());
4766       pss.print_termination_stats(i);
4767     }
4768 
4769     assert(pss.refs()->is_empty(), "should be empty");
4770     double end_time_ms = os::elapsedTime() * 1000.0;
4771     _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4772   }
4773 };
4774 
4775 // *** Common G1 Evacuation Stuff
4776 
4777 // This method is run in a GC worker.
4778 
4779 void
4780 G1CollectedHeap::
4781 g1_process_strong_roots(bool collecting_perm_gen,
4782                         SharedHeap::ScanningOption so,
4783                         OopClosure* scan_non_heap_roots,
4784                         OopsInHeapRegionClosure* scan_rs,
4785                         OopsInGenClosure* scan_perm,
4786                         int worker_i) {
4787 
4788   // First scan the strong roots, including the perm gen.
4789   double ext_roots_start = os::elapsedTime();
4790   double closure_app_time_sec = 0.0;
4791 
4792   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4793   BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4794   buf_scan_perm.set_generation(perm_gen());
4795 
4796   // Walk the code cache w/o buffering, because StarTask cannot handle
4797   // unaligned oop locations.
4798   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4799 
4800   process_strong_roots(false, // no scoping; this is parallel code
4801                        collecting_perm_gen, so,
4802                        &buf_scan_non_heap_roots,
4803                        &eager_scan_code_roots,
4804                        &buf_scan_perm);
4805 
4806   // Now the CM ref_processor roots.
4807   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4808     // We need to treat the discovered reference lists of the
4809     // concurrent mark ref processor as roots and keep entries
4810     // (which are added by the marking threads) on them live
4811     // until they can be processed at the end of marking.
4812     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4813   }
4814 
4815   // Finish up any enqueued closure apps (attributed as object copy time).
4816   buf_scan_non_heap_roots.done();
4817   buf_scan_perm.done();
4818 
4819   double ext_roots_end = os::elapsedTime();
4820 
4821   g1_policy()->reset_obj_copy_time(worker_i);
4822   double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4823                                 buf_scan_non_heap_roots.closure_app_seconds();
4824   g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4825 
4826   double ext_root_time_ms =
4827     ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4828 
4829   g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4830 
4831   // Scan strong roots in mark stack.
4832   if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4833     concurrent_mark()->oops_do(scan_non_heap_roots);
4834   }
4835   double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4836   g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4837 
4838   // Now scan the complement of the collection set.
4839   if (scan_rs != NULL) {
4840     g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4841   }
4842 
4843   _process_strong_tasks->all_tasks_completed();
4844 }
4845 
4846 void
4847 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4848                                        OopClosure* non_root_closure) {
4849   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4850   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4851 }
4852 
4853 // Weak Reference Processing support
4854 
4855 // An always "is_alive" closure that is used to preserve referents.
4856 // If the object is non-null then it's alive.  Used in the preservation
4857 // of referent objects that are pointed to by reference objects
4858 // discovered by the CM ref processor.
4859 class G1AlwaysAliveClosure: public BoolObjectClosure {
4860   G1CollectedHeap* _g1;
4861 public:
4862   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4863   void do_object(oop p) { assert(false, "Do not call."); }
4864   bool do_object_b(oop p) {
4865     if (p != NULL) {
4866       return true;
4867     }
4868     return false;
4869   }
4870 };
4871 
4872 bool G1STWIsAliveClosure::do_object_b(oop p) {
4873   // An object is reachable if it is outside the collection set,
4874   // or is inside and copied.
4875   return !_g1->obj_in_cs(p) || p->is_forwarded();
4876 }
4877 
4878 // Non Copying Keep Alive closure
4879 class G1KeepAliveClosure: public OopClosure {
4880   G1CollectedHeap* _g1;
4881 public:
4882   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4883   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4884   void do_oop(      oop* p) {
4885     oop obj = *p;
4886 
4887     if (_g1->obj_in_cs(obj)) {
4888       assert( obj->is_forwarded(), "invariant" );
4889       *p = obj->forwardee();
4890     }
4891   }
4892 };
4893 
4894 // Copying Keep Alive closure - can be called from both
4895 // serial and parallel code as long as different worker
4896 // threads utilize different G1ParScanThreadState instances
4897 // and different queues.
4898 
4899 class G1CopyingKeepAliveClosure: public OopClosure {
4900   G1CollectedHeap*         _g1h;
4901   OopClosure*              _copy_non_heap_obj_cl;
4902   OopsInHeapRegionClosure* _copy_perm_obj_cl;
4903   G1ParScanThreadState*    _par_scan_state;
4904 
4905 public:
4906   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4907                             OopClosure* non_heap_obj_cl,
4908                             OopsInHeapRegionClosure* perm_obj_cl,
4909                             G1ParScanThreadState* pss):
4910     _g1h(g1h),
4911     _copy_non_heap_obj_cl(non_heap_obj_cl),
4912     _copy_perm_obj_cl(perm_obj_cl),
4913     _par_scan_state(pss)
4914   {}
4915 
4916   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4917   virtual void do_oop(      oop* p) { do_oop_work(p); }
4918 
4919   template <class T> void do_oop_work(T* p) {
4920     oop obj = oopDesc::load_decode_heap_oop(p);
4921 
4922     if (_g1h->obj_in_cs(obj)) {
4923       // If the referent object has been forwarded (either copied
4924       // to a new location or to itself in the event of an
4925       // evacuation failure) then we need to update the reference
4926       // field and, if both reference and referent are in the G1
4927       // heap, update the RSet for the referent.
4928       //
4929       // If the referent has not been forwarded then we have to keep
4930       // it alive by policy. Therefore we have copy the referent.
4931       //
4932       // If the reference field is in the G1 heap then we can push
4933       // on the PSS queue. When the queue is drained (after each
4934       // phase of reference processing) the object and it's followers
4935       // will be copied, the reference field set to point to the
4936       // new location, and the RSet updated. Otherwise we need to
4937       // use the the non-heap or perm closures directly to copy
4938       // the refernt object and update the pointer, while avoiding
4939       // updating the RSet.
4940 
4941       if (_g1h->is_in_g1_reserved(p)) {
4942         _par_scan_state->push_on_queue(p);
4943       } else {
4944         // The reference field is not in the G1 heap.
4945         if (_g1h->perm_gen()->is_in(p)) {
4946           _copy_perm_obj_cl->do_oop(p);
4947         } else {
4948           _copy_non_heap_obj_cl->do_oop(p);
4949         }
4950       }
4951     }
4952   }
4953 };
4954 
4955 // Serial drain queue closure. Called as the 'complete_gc'
4956 // closure for each discovered list in some of the
4957 // reference processing phases.
4958 
4959 class G1STWDrainQueueClosure: public VoidClosure {
4960 protected:
4961   G1CollectedHeap* _g1h;
4962   G1ParScanThreadState* _par_scan_state;
4963 
4964   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4965 
4966 public:
4967   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4968     _g1h(g1h),
4969     _par_scan_state(pss)
4970   { }
4971 
4972   void do_void() {
4973     G1ParScanThreadState* const pss = par_scan_state();
4974     pss->trim_queue();
4975   }
4976 };
4977 
4978 // Parallel Reference Processing closures
4979 
4980 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4981 // processing during G1 evacuation pauses.
4982 
4983 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4984 private:
4985   G1CollectedHeap*   _g1h;
4986   RefToScanQueueSet* _queues;
4987   FlexibleWorkGang*  _workers;
4988   int                _active_workers;
4989 
4990 public:
4991   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4992                         FlexibleWorkGang* workers,
4993                         RefToScanQueueSet *task_queues,
4994                         int n_workers) :
4995     _g1h(g1h),
4996     _queues(task_queues),
4997     _workers(workers),
4998     _active_workers(n_workers)
4999   {
5000     assert(n_workers > 0, "shouldn't call this otherwise");
5001   }
5002 
5003   // Executes the given task using concurrent marking worker threads.
5004   virtual void execute(ProcessTask& task);
5005   virtual void execute(EnqueueTask& task);
5006 };
5007 
5008 // Gang task for possibly parallel reference processing
5009 
5010 class G1STWRefProcTaskProxy: public AbstractGangTask {
5011   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5012   ProcessTask&     _proc_task;
5013   G1CollectedHeap* _g1h;
5014   RefToScanQueueSet *_task_queues;
5015   ParallelTaskTerminator* _terminator;
5016 
5017 public:
5018   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5019                      G1CollectedHeap* g1h,
5020                      RefToScanQueueSet *task_queues,
5021                      ParallelTaskTerminator* terminator) :
5022     AbstractGangTask("Process reference objects in parallel"),
5023     _proc_task(proc_task),
5024     _g1h(g1h),
5025     _task_queues(task_queues),
5026     _terminator(terminator)
5027   {}
5028 
5029   virtual void work(int i) {
5030     // The reference processing task executed by a single worker.
5031     ResourceMark rm;
5032     HandleMark   hm;
5033 
5034     G1STWIsAliveClosure is_alive(_g1h);
5035 
5036     G1ParScanThreadState pss(_g1h, i);
5037 
5038     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5039     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5040     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5041 
5042     pss.set_evac_closure(&scan_evac_cl);
5043     pss.set_evac_failure_closure(&evac_failure_cl);
5044     pss.set_partial_scan_closure(&partial_scan_cl);
5045 
5046     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5047     G1ParScanPermClosure           only_copy_perm_cl(_g1h, &pss, NULL);
5048 
5049     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5050     G1ParScanAndMarkPermClosure    copy_mark_perm_cl(_g1h, &pss, NULL);
5051 
5052     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5053     OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
5054 
5055     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5056       // We also need to mark copied objects.
5057       copy_non_heap_cl = &copy_mark_non_heap_cl;
5058       copy_perm_cl = &copy_mark_perm_cl;
5059     }
5060 
5061     // Keep alive closure.
5062     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5063 
5064     // Complete GC closure
5065     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5066 
5067     // Call the reference processing task's work routine.
5068     _proc_task.work(i, is_alive, keep_alive, drain_queue);
5069 
5070     // Note we cannot assert that the refs array is empty here as not all
5071     // of the processing tasks (specifically phase2 - pp2_work) execute
5072     // the complete_gc closure (which ordinarily would drain the queue) so
5073     // the queue may not be empty.
5074   }
5075 };
5076 
5077 // Driver routine for parallel reference processing.
5078 // Creates an instance of the ref processing gang
5079 // task and has the worker threads execute it.
5080 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5081   assert(_workers != NULL, "Need parallel worker threads.");
5082 
5083   ParallelTaskTerminator terminator(_active_workers, _queues);
5084   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5085 
5086   _g1h->set_par_threads(_active_workers);
5087   _workers->run_task(&proc_task_proxy);
5088   _g1h->set_par_threads(0);
5089 }
5090 
5091 // Gang task for parallel reference enqueueing.
5092 
5093 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5094   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5095   EnqueueTask& _enq_task;
5096 
5097 public:
5098   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5099     AbstractGangTask("Enqueue reference objects in parallel"),
5100     _enq_task(enq_task)
5101   { }
5102 
5103   virtual void work(int i) {
5104     _enq_task.work(i);
5105   }
5106 };
5107 
5108 // Driver routine for parallel reference enqueing.
5109 // Creates an instance of the ref enqueueing gang
5110 // task and has the worker threads execute it.
5111 
5112 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5113   assert(_workers != NULL, "Need parallel worker threads.");
5114 
5115   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5116 
5117   _g1h->set_par_threads(_active_workers);
5118   _workers->run_task(&enq_task_proxy);
5119   _g1h->set_par_threads(0);
5120 }
5121 
5122 // End of weak reference support closures
5123 
5124 // Abstract task used to preserve (i.e. copy) any referent objects
5125 // that are in the collection set and are pointed to by reference
5126 // objects discovered by the CM ref processor.
5127 
5128 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5129 protected:
5130   G1CollectedHeap* _g1h;
5131   RefToScanQueueSet      *_queues;
5132   ParallelTaskTerminator _terminator;
5133   int _n_workers;
5134 
5135 public:
5136   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5137     AbstractGangTask("ParPreserveCMReferents"),
5138     _g1h(g1h),
5139     _queues(task_queues),
5140     _terminator(workers, _queues),
5141     _n_workers(workers)
5142   { }
5143 
5144   void work(int i) {
5145     ResourceMark rm;
5146     HandleMark   hm;
5147 
5148     G1ParScanThreadState            pss(_g1h, i);
5149     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5150     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5151     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5152 
5153     pss.set_evac_closure(&scan_evac_cl);
5154     pss.set_evac_failure_closure(&evac_failure_cl);
5155     pss.set_partial_scan_closure(&partial_scan_cl);
5156 
5157     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5158 
5159 
5160     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5161     G1ParScanPermClosure           only_copy_perm_cl(_g1h, &pss, NULL);
5162 
5163     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5164     G1ParScanAndMarkPermClosure    copy_mark_perm_cl(_g1h, &pss, NULL);
5165 
5166     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5167     OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
5168 
5169     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5170       // We also need to mark copied objects.
5171       copy_non_heap_cl = &copy_mark_non_heap_cl;
5172       copy_perm_cl = &copy_mark_perm_cl;
5173     }
5174 
5175     // Is alive closure
5176     G1AlwaysAliveClosure always_alive(_g1h);
5177 
5178     // Copying keep alive closure. Applied to referent objects that need
5179     // to be copied.
5180     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5181 
5182     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5183 
5184     int limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5185     int stride = MIN2(MAX2(_n_workers, 1), limit);
5186 
5187     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5188     // So this must be true - but assert just in case someone decides to
5189     // change the worker ids.
5190     assert(0 <= i && i < limit, "sanity");
5191     assert(!rp->discovery_is_atomic(), "check this code");
5192 
5193     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5194     for (int idx = i; idx < limit; idx += stride) {
5195       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5196 
5197       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5198       while (iter.has_next()) {
5199         // Since discovery is not atomic for the CM ref processor, we
5200         // can see some null referent objects.
5201         iter.load_ptrs(DEBUG_ONLY(true));
5202         oop ref = iter.obj();
5203 
5204         // This will filter nulls.
5205         if (iter.is_referent_alive()) {
5206           iter.make_referent_alive();
5207         }
5208         iter.move_to_next();
5209       }
5210     }
5211 
5212     // Drain the queue - which may cause stealing
5213     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5214     drain_queue.do_void();
5215     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5216     assert(pss.refs()->is_empty(), "should be");
5217   }
5218 };
5219 
5220 // Weak Reference processing during an evacuation pause (part 1).
5221 void G1CollectedHeap::process_discovered_references() {
5222   double ref_proc_start = os::elapsedTime();
5223 
5224   ReferenceProcessor* rp = _ref_processor_stw;
5225   assert(rp->discovery_enabled(), "should have been enabled");
5226 
5227   // Any reference objects, in the collection set, that were 'discovered'
5228   // by the CM ref processor should have already been copied (either by
5229   // applying the external root copy closure to the discovered lists, or
5230   // by following an RSet entry).
5231   //
5232   // But some of the referents, that are in the collection set, that these
5233   // reference objects point to may not have been copied: the STW ref
5234   // processor would have seen that the reference object had already
5235   // been 'discovered' and would have skipped discovering the reference,
5236   // but would not have treated the reference object as a regular oop.
5237   // As a reult the copy closure would not have been applied to the
5238   // referent object.
5239   //
5240   // We need to explicitly copy these referent objects - the references
5241   // will be processed at the end of remarking.
5242   //
5243   // We also need to do this copying before we process the reference
5244   // objects discovered by the STW ref processor in case one of these
5245   // referents points to another object which is also referenced by an
5246   // object discovered by the STW ref processor.
5247 
5248   int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5249                         workers()->active_workers() : 1);
5250 
5251   assert(active_workers == workers()->active_workers(),
5252          "Need to reset active_workers");
5253   set_par_threads(active_workers);
5254   G1ParPreserveCMReferentsTask keep_cm_referents(this, active_workers, _task_queues);
5255 
5256   if (G1CollectedHeap::use_parallel_gc_threads()) {
5257     workers()->run_task(&keep_cm_referents);
5258   } else {
5259     keep_cm_referents.work(0);
5260   }
5261 
5262   set_par_threads(0);
5263 
5264   // Closure to test whether a referent is alive.
5265   G1STWIsAliveClosure is_alive(this);
5266 
5267   // Even when parallel reference processing is enabled, the processing
5268   // of JNI refs is serial and performed serially by the current thread
5269   // rather than by a worker. The following PSS will be used for processing
5270   // JNI refs.
5271 
5272   // Use only a single queue for this PSS.
5273   G1ParScanThreadState pss(this, 0);
5274 
5275   // We do not embed a reference processor in the copying/scanning
5276   // closures while we're actually processing the discovered
5277   // reference objects.
5278   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5279   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5280   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5281 
5282   pss.set_evac_closure(&scan_evac_cl);
5283   pss.set_evac_failure_closure(&evac_failure_cl);
5284   pss.set_partial_scan_closure(&partial_scan_cl);
5285 
5286   assert(pss.refs()->is_empty(), "pre-condition");
5287 
5288   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5289   G1ParScanPermClosure           only_copy_perm_cl(this, &pss, NULL);
5290 
5291   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5292   G1ParScanAndMarkPermClosure    copy_mark_perm_cl(this, &pss, NULL);
5293 
5294   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5295   OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
5296 
5297   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5298     // We also need to mark copied objects.
5299     copy_non_heap_cl = &copy_mark_non_heap_cl;
5300     copy_perm_cl = &copy_mark_perm_cl;
5301   }
5302 
5303   // Keep alive closure.
5304   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5305 
5306   // Serial Complete GC closure
5307   G1STWDrainQueueClosure drain_queue(this, &pss);
5308 
5309   // Setup the soft refs policy...
5310   rp->setup_policy(false);
5311 
5312   if (!rp->processing_is_mt()) {
5313     // Serial reference processing...
5314     rp->process_discovered_references(&is_alive,
5315                                       &keep_alive,
5316                                       &drain_queue,
5317                                       NULL);
5318   } else {
5319     // Parallel reference processing
5320     assert(rp->num_q() == active_workers, "sanity");
5321     assert(active_workers <= rp->max_num_q(), "sanity");
5322 
5323     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5324     rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5325   }
5326 
5327   // We have completed copying any necessary live referent objects
5328   // (that were not copied during the actual pause) so we can
5329   // retire any active alloc buffers
5330   pss.retire_alloc_buffers();
5331   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5332 
5333   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5334   g1_policy()->record_ref_proc_time(ref_proc_time * 1000.0);
5335 }
5336 
5337 // Weak Reference processing during an evacuation pause (part 2).
5338 void G1CollectedHeap::enqueue_discovered_references() {
5339   double ref_enq_start = os::elapsedTime();
5340 
5341   ReferenceProcessor* rp = _ref_processor_stw;
5342   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5343 
5344   // Now enqueue any remaining on the discovered lists on to
5345   // the pending list.
5346   if (!rp->processing_is_mt()) {
5347     // Serial reference processing...
5348     rp->enqueue_discovered_references();
5349   } else {
5350     // Parallel reference enqueuing
5351 
5352     int active_workers = (ParallelGCThreads > 0 ? workers()->active_workers() : 1);
5353     assert(active_workers == workers()->active_workers(),
5354            "Need to reset active_workers");
5355     assert(rp->num_q() == active_workers, "sanity");
5356     assert(active_workers <= rp->max_num_q(), "sanity");
5357 
5358     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5359     rp->enqueue_discovered_references(&par_task_executor);
5360   }
5361 
5362   rp->verify_no_references_recorded();
5363   assert(!rp->discovery_enabled(), "should have been disabled");
5364 
5365   // FIXME
5366   // CM's reference processing also cleans up the string and symbol tables.
5367   // Should we do that here also? We could, but it is a serial operation
5368   // and could signicantly increase the pause time.
5369 
5370   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5371   g1_policy()->record_ref_enq_time(ref_enq_time * 1000.0);
5372 }
5373 
5374 void G1CollectedHeap::evacuate_collection_set() {
5375   set_evacuation_failed(false);
5376 
5377   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5378   concurrent_g1_refine()->set_use_cache(false);
5379   concurrent_g1_refine()->clear_hot_cache_claimed_index();
5380 
5381   int n_workers;
5382   if (G1CollectedHeap::use_parallel_gc_threads()) {
5383     n_workers =
5384       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5385                                      workers()->active_workers(),
5386                                      Threads::number_of_non_daemon_threads());
5387     assert(UseDynamicNumberOfGCThreads ||
5388            n_workers == workers()->total_workers(),
5389            "If not dynamic should be using all the  workers");
5390     set_par_threads(n_workers);
5391   } else {
5392     assert(n_par_threads() == 0,
5393            "Should be the original non-parallel value");
5394     n_workers = 1;
5395   }
5396   workers()->set_active_workers(n_workers);
5397 
5398   G1ParTask g1_par_task(this, _task_queues);
5399 
5400   init_for_evac_failure(NULL);
5401 
5402   rem_set()->prepare_for_younger_refs_iterate(true);
5403 
5404   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5405   double start_par = os::elapsedTime();
5406 
5407   if (G1CollectedHeap::use_parallel_gc_threads()) {
5408     // The individual threads will set their evac-failure closures.
5409     StrongRootsScope srs(this);
5410     if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5411     // These tasks use ShareHeap::_process_strong_tasks
5412     assert(UseDynamicNumberOfGCThreads ||
5413            workers()->active_workers() == workers()->total_workers(),
5414            "If not dynamic should be using all the  workers");
5415     workers()->run_task(&g1_par_task);
5416   } else {
5417     StrongRootsScope srs(this);
5418     g1_par_task.work(0);
5419   }
5420 
5421   double par_time = (os::elapsedTime() - start_par) * 1000.0;
5422   g1_policy()->record_par_time(par_time);
5423 
5424   set_par_threads(0);
5425 
5426   // Process any discovered reference objects - we have
5427   // to do this _before_ we retire the GC alloc regions
5428   // as we may have to copy some 'reachable' referent
5429   // objects (and their reachable sub-graphs) that were
5430   // not copied during the pause.
5431   process_discovered_references();
5432 
5433   // Weak root processing.
5434   // Note: when JSR 292 is enabled and code blobs can contain
5435   // non-perm oops then we will need to process the code blobs
5436   // here too.
5437   {
5438     G1STWIsAliveClosure is_alive(this);
5439     G1KeepAliveClosure keep_alive(this);
5440     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5441   }
5442 
5443   release_gc_alloc_regions();
5444   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5445 
5446   concurrent_g1_refine()->clear_hot_cache();
5447   concurrent_g1_refine()->set_use_cache(true);
5448 
5449   finalize_for_evac_failure();
5450 
5451   // Must do this before clearing the per-region evac-failure flags
5452   // (which is currently done when we free the collection set).
5453   // We also only do this if marking is actually in progress and so
5454   // have to do this before we set the mark_in_progress flag at the
5455   // end of an initial mark pause.
5456   concurrent_mark()->complete_marking_in_collection_set();
5457 
5458   if (evacuation_failed()) {
5459     remove_self_forwarding_pointers();
5460     if (PrintGCDetails) {
5461       gclog_or_tty->print(" (to-space overflow)");
5462     } else if (PrintGC) {
5463       gclog_or_tty->print("--");
5464     }
5465   }
5466 
5467   // Enqueue any remaining references remaining on the STW
5468   // reference processor's discovered lists. We need to do
5469   // this after the card table is cleaned (and verified) as
5470   // the act of enqueuing entries on to the pending list
5471   // will log these updates (and dirty their associated
5472   // cards). We need these updates logged to update any
5473   // RSets.
5474   enqueue_discovered_references();
5475 
5476   if (G1DeferredRSUpdate) {
5477     RedirtyLoggedCardTableEntryFastClosure redirty;
5478     dirty_card_queue_set().set_closure(&redirty);
5479     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5480 
5481     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5482     dcq.merge_bufferlists(&dirty_card_queue_set());
5483     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5484   }
5485   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5486 }
5487 
5488 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5489                                      size_t* pre_used,
5490                                      FreeRegionList* free_list,
5491                                      OldRegionSet* old_proxy_set,
5492                                      HumongousRegionSet* humongous_proxy_set,
5493                                      HRRSCleanupTask* hrrs_cleanup_task,
5494                                      bool par) {
5495   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5496     if (hr->isHumongous()) {
5497       assert(hr->startsHumongous(), "we should only see starts humongous");
5498       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5499     } else {
5500       _old_set.remove_with_proxy(hr, old_proxy_set);
5501       free_region(hr, pre_used, free_list, par);
5502     }
5503   } else {
5504     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5505   }
5506 }
5507 
5508 void G1CollectedHeap::free_region(HeapRegion* hr,
5509                                   size_t* pre_used,
5510                                   FreeRegionList* free_list,
5511                                   bool par) {
5512   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5513   assert(!hr->is_empty(), "the region should not be empty");
5514   assert(free_list != NULL, "pre-condition");
5515 
5516   *pre_used += hr->used();
5517   hr->hr_clear(par, true /* clear_space */);
5518   free_list->add_as_head(hr);
5519 }
5520 
5521 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5522                                      size_t* pre_used,
5523                                      FreeRegionList* free_list,
5524                                      HumongousRegionSet* humongous_proxy_set,
5525                                      bool par) {
5526   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5527   assert(free_list != NULL, "pre-condition");
5528   assert(humongous_proxy_set != NULL, "pre-condition");
5529 
5530   size_t hr_used = hr->used();
5531   size_t hr_capacity = hr->capacity();
5532   size_t hr_pre_used = 0;
5533   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5534   hr->set_notHumongous();
5535   free_region(hr, &hr_pre_used, free_list, par);
5536 
5537   size_t i = hr->hrs_index() + 1;
5538   size_t num = 1;
5539   while (i < n_regions()) {
5540     HeapRegion* curr_hr = region_at(i);
5541     if (!curr_hr->continuesHumongous()) {
5542       break;
5543     }
5544     curr_hr->set_notHumongous();
5545     free_region(curr_hr, &hr_pre_used, free_list, par);
5546     num += 1;
5547     i += 1;
5548   }
5549   assert(hr_pre_used == hr_used,
5550          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5551                  "should be the same", hr_pre_used, hr_used));
5552   *pre_used += hr_pre_used;
5553 }
5554 
5555 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5556                                        FreeRegionList* free_list,
5557                                        OldRegionSet* old_proxy_set,
5558                                        HumongousRegionSet* humongous_proxy_set,
5559                                        bool par) {
5560   if (pre_used > 0) {
5561     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5562     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5563     assert(_summary_bytes_used >= pre_used,
5564            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5565                    "should be >= pre_used: "SIZE_FORMAT,
5566                    _summary_bytes_used, pre_used));
5567     _summary_bytes_used -= pre_used;
5568   }
5569   if (free_list != NULL && !free_list->is_empty()) {
5570     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5571     _free_list.add_as_head(free_list);
5572   }
5573   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5574     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5575     _old_set.update_from_proxy(old_proxy_set);
5576   }
5577   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5578     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5579     _humongous_set.update_from_proxy(humongous_proxy_set);
5580   }
5581 }
5582 
5583 class G1ParCleanupCTTask : public AbstractGangTask {
5584   CardTableModRefBS* _ct_bs;
5585   G1CollectedHeap* _g1h;
5586   HeapRegion* volatile _su_head;
5587 public:
5588   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5589                      G1CollectedHeap* g1h) :
5590     AbstractGangTask("G1 Par Cleanup CT Task"),
5591     _ct_bs(ct_bs), _g1h(g1h) { }
5592 
5593   void work(int i) {
5594     HeapRegion* r;
5595     while (r = _g1h->pop_dirty_cards_region()) {
5596       clear_cards(r);
5597     }
5598   }
5599 
5600   void clear_cards(HeapRegion* r) {
5601     // Cards of the survivors should have already been dirtied.
5602     if (!r->is_survivor()) {
5603       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5604     }
5605   }
5606 };
5607 
5608 #ifndef PRODUCT
5609 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5610   G1CollectedHeap* _g1h;
5611   CardTableModRefBS* _ct_bs;
5612 public:
5613   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5614     : _g1h(g1h), _ct_bs(ct_bs) { }
5615   virtual bool doHeapRegion(HeapRegion* r) {
5616     if (r->is_survivor()) {
5617       _g1h->verify_dirty_region(r);
5618     } else {
5619       _g1h->verify_not_dirty_region(r);
5620     }
5621     return false;
5622   }
5623 };
5624 
5625 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5626   // All of the region should be clean.
5627   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5628   MemRegion mr(hr->bottom(), hr->end());
5629   ct_bs->verify_not_dirty_region(mr);
5630 }
5631 
5632 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5633   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5634   // dirty allocated blocks as they allocate them. The thread that
5635   // retires each region and replaces it with a new one will do a
5636   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5637   // not dirty that area (one less thing to have to do while holding
5638   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5639   // is dirty.
5640   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5641   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5642   ct_bs->verify_dirty_region(mr);
5643 }
5644 
5645 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5646   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5647   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5648     verify_dirty_region(hr);
5649   }
5650 }
5651 
5652 void G1CollectedHeap::verify_dirty_young_regions() {
5653   verify_dirty_young_list(_young_list->first_region());
5654   verify_dirty_young_list(_young_list->first_survivor_region());
5655 }
5656 #endif
5657 
5658 void G1CollectedHeap::cleanUpCardTable() {
5659   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5660   double start = os::elapsedTime();
5661 
5662   {
5663     // Iterate over the dirty cards region list.
5664     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5665 
5666     if (ParallelGCThreads > 0) {
5667       set_par_threads(workers()->total_workers());
5668       workers()->run_task(&cleanup_task);
5669       set_par_threads(0);
5670     } else {
5671       while (_dirty_cards_region_list) {
5672         HeapRegion* r = _dirty_cards_region_list;
5673         cleanup_task.clear_cards(r);
5674         _dirty_cards_region_list = r->get_next_dirty_cards_region();
5675         if (_dirty_cards_region_list == r) {
5676           // The last region.
5677           _dirty_cards_region_list = NULL;
5678         }
5679         r->set_next_dirty_cards_region(NULL);
5680       }
5681     }
5682 #ifndef PRODUCT
5683     if (G1VerifyCTCleanup || VerifyAfterGC) {
5684       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5685       heap_region_iterate(&cleanup_verifier);
5686     }
5687 #endif
5688   }
5689 
5690   double elapsed = os::elapsedTime() - start;
5691   g1_policy()->record_clear_ct_time(elapsed * 1000.0);
5692 }
5693 
5694 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5695   size_t pre_used = 0;
5696   FreeRegionList local_free_list("Local List for CSet Freeing");
5697 
5698   double young_time_ms     = 0.0;
5699   double non_young_time_ms = 0.0;
5700 
5701   // Since the collection set is a superset of the the young list,
5702   // all we need to do to clear the young list is clear its
5703   // head and length, and unlink any young regions in the code below
5704   _young_list->clear();
5705 
5706   G1CollectorPolicy* policy = g1_policy();
5707 
5708   double start_sec = os::elapsedTime();
5709   bool non_young = true;
5710 
5711   HeapRegion* cur = cs_head;
5712   int age_bound = -1;
5713   size_t rs_lengths = 0;
5714 
5715   while (cur != NULL) {
5716     assert(!is_on_master_free_list(cur), "sanity");
5717     if (non_young) {
5718       if (cur->is_young()) {
5719         double end_sec = os::elapsedTime();
5720         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5721         non_young_time_ms += elapsed_ms;
5722 
5723         start_sec = os::elapsedTime();
5724         non_young = false;
5725       }
5726     } else {
5727       if (!cur->is_young()) {
5728         double end_sec = os::elapsedTime();
5729         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5730         young_time_ms += elapsed_ms;
5731 
5732         start_sec = os::elapsedTime();
5733         non_young = true;
5734       }
5735     }
5736 
5737     rs_lengths += cur->rem_set()->occupied();
5738 
5739     HeapRegion* next = cur->next_in_collection_set();
5740     assert(cur->in_collection_set(), "bad CS");
5741     cur->set_next_in_collection_set(NULL);
5742     cur->set_in_collection_set(false);
5743 
5744     if (cur->is_young()) {
5745       int index = cur->young_index_in_cset();
5746       assert(index != -1, "invariant");
5747       assert((size_t) index < policy->young_cset_region_length(), "invariant");
5748       size_t words_survived = _surviving_young_words[index];
5749       cur->record_surv_words_in_group(words_survived);
5750 
5751       // At this point the we have 'popped' cur from the collection set
5752       // (linked via next_in_collection_set()) but it is still in the
5753       // young list (linked via next_young_region()). Clear the
5754       // _next_young_region field.
5755       cur->set_next_young_region(NULL);
5756     } else {
5757       int index = cur->young_index_in_cset();
5758       assert(index == -1, "invariant");
5759     }
5760 
5761     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5762             (!cur->is_young() && cur->young_index_in_cset() == -1),
5763             "invariant" );
5764 
5765     if (!cur->evacuation_failed()) {
5766       MemRegion used_mr = cur->used_region();
5767 
5768       // And the region is empty.
5769       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5770 
5771       // If marking is in progress then clear any objects marked in
5772       // the current region. Note mark_in_progress() returns false,
5773       // even during an initial mark pause, until the set_marking_started()
5774       // call which takes place later in the pause.
5775       if (mark_in_progress()) {
5776         assert(!g1_policy()->during_initial_mark_pause(), "sanity");
5777         _cm->nextMarkBitMap()->clearRange(used_mr);
5778       }
5779 
5780       free_region(cur, &pre_used, &local_free_list, false /* par */);
5781     } else {
5782       cur->uninstall_surv_rate_group();
5783       if (cur->is_young()) {
5784         cur->set_young_index_in_cset(-1);
5785       }
5786       cur->set_not_young();
5787       cur->set_evacuation_failed(false);
5788       // The region is now considered to be old.
5789       _old_set.add(cur);
5790     }
5791     cur = next;
5792   }
5793 
5794   policy->record_max_rs_lengths(rs_lengths);
5795   policy->cset_regions_freed();
5796 
5797   double end_sec = os::elapsedTime();
5798   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5799 
5800   if (non_young) {
5801     non_young_time_ms += elapsed_ms;
5802   } else {
5803     young_time_ms += elapsed_ms;
5804   }
5805 
5806   update_sets_after_freeing_regions(pre_used, &local_free_list,
5807                                     NULL /* old_proxy_set */,
5808                                     NULL /* humongous_proxy_set */,
5809                                     false /* par */);
5810   policy->record_young_free_cset_time_ms(young_time_ms);
5811   policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5812 }
5813 
5814 // This routine is similar to the above but does not record
5815 // any policy statistics or update free lists; we are abandoning
5816 // the current incremental collection set in preparation of a
5817 // full collection. After the full GC we will start to build up
5818 // the incremental collection set again.
5819 // This is only called when we're doing a full collection
5820 // and is immediately followed by the tearing down of the young list.
5821 
5822 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5823   HeapRegion* cur = cs_head;
5824 
5825   while (cur != NULL) {
5826     HeapRegion* next = cur->next_in_collection_set();
5827     assert(cur->in_collection_set(), "bad CS");
5828     cur->set_next_in_collection_set(NULL);
5829     cur->set_in_collection_set(false);
5830     cur->set_young_index_in_cset(-1);
5831     cur = next;
5832   }
5833 }
5834 
5835 void G1CollectedHeap::set_free_regions_coming() {
5836   if (G1ConcRegionFreeingVerbose) {
5837     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5838                            "setting free regions coming");
5839   }
5840 
5841   assert(!free_regions_coming(), "pre-condition");
5842   _free_regions_coming = true;
5843 }
5844 
5845 void G1CollectedHeap::reset_free_regions_coming() {
5846   {
5847     assert(free_regions_coming(), "pre-condition");
5848     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5849     _free_regions_coming = false;
5850     SecondaryFreeList_lock->notify_all();
5851   }
5852 
5853   if (G1ConcRegionFreeingVerbose) {
5854     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5855                            "reset free regions coming");
5856   }
5857 }
5858 
5859 void G1CollectedHeap::wait_while_free_regions_coming() {
5860   // Most of the time we won't have to wait, so let's do a quick test
5861   // first before we take the lock.
5862   if (!free_regions_coming()) {
5863     return;
5864   }
5865 
5866   if (G1ConcRegionFreeingVerbose) {
5867     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5868                            "waiting for free regions");
5869   }
5870 
5871   {
5872     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5873     while (free_regions_coming()) {
5874       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5875     }
5876   }
5877 
5878   if (G1ConcRegionFreeingVerbose) {
5879     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5880                            "done waiting for free regions");
5881   }
5882 }
5883 
5884 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5885   assert(heap_lock_held_for_gc(),
5886               "the heap lock should already be held by or for this thread");
5887   _young_list->push_region(hr);
5888 }
5889 
5890 class NoYoungRegionsClosure: public HeapRegionClosure {
5891 private:
5892   bool _success;
5893 public:
5894   NoYoungRegionsClosure() : _success(true) { }
5895   bool doHeapRegion(HeapRegion* r) {
5896     if (r->is_young()) {
5897       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5898                              r->bottom(), r->end());
5899       _success = false;
5900     }
5901     return false;
5902   }
5903   bool success() { return _success; }
5904 };
5905 
5906 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5907   bool ret = _young_list->check_list_empty(check_sample);
5908 
5909   if (check_heap) {
5910     NoYoungRegionsClosure closure;
5911     heap_region_iterate(&closure);
5912     ret = ret && closure.success();
5913   }
5914 
5915   return ret;
5916 }
5917 
5918 class TearDownRegionSetsClosure : public HeapRegionClosure {
5919 private:
5920   OldRegionSet *_old_set;
5921 
5922 public:
5923   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
5924 
5925   bool doHeapRegion(HeapRegion* r) {
5926     if (r->is_empty()) {
5927       // We ignore empty regions, we'll empty the free list afterwards
5928     } else if (r->is_young()) {
5929       // We ignore young regions, we'll empty the young list afterwards
5930     } else if (r->isHumongous()) {
5931       // We ignore humongous regions, we're not tearing down the
5932       // humongous region set
5933     } else {
5934       // The rest should be old
5935       _old_set->remove(r);
5936     }
5937     return false;
5938   }
5939 
5940   ~TearDownRegionSetsClosure() {
5941     assert(_old_set->is_empty(), "post-condition");
5942   }
5943 };
5944 
5945 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5946   assert_at_safepoint(true /* should_be_vm_thread */);
5947 
5948   if (!free_list_only) {
5949     TearDownRegionSetsClosure cl(&_old_set);
5950     heap_region_iterate(&cl);
5951 
5952     // Need to do this after the heap iteration to be able to
5953     // recognize the young regions and ignore them during the iteration.
5954     _young_list->empty_list();
5955   }
5956   _free_list.remove_all();
5957 }
5958 
5959 class RebuildRegionSetsClosure : public HeapRegionClosure {
5960 private:
5961   bool            _free_list_only;
5962   OldRegionSet*   _old_set;
5963   FreeRegionList* _free_list;
5964   size_t          _total_used;
5965 
5966 public:
5967   RebuildRegionSetsClosure(bool free_list_only,
5968                            OldRegionSet* old_set, FreeRegionList* free_list) :
5969     _free_list_only(free_list_only),
5970     _old_set(old_set), _free_list(free_list), _total_used(0) {
5971     assert(_free_list->is_empty(), "pre-condition");
5972     if (!free_list_only) {
5973       assert(_old_set->is_empty(), "pre-condition");
5974     }
5975   }
5976 
5977   bool doHeapRegion(HeapRegion* r) {
5978     if (r->continuesHumongous()) {
5979       return false;
5980     }
5981 
5982     if (r->is_empty()) {
5983       // Add free regions to the free list
5984       _free_list->add_as_tail(r);
5985     } else if (!_free_list_only) {
5986       assert(!r->is_young(), "we should not come across young regions");
5987 
5988       if (r->isHumongous()) {
5989         // We ignore humongous regions, we left the humongous set unchanged
5990       } else {
5991         // The rest should be old, add them to the old set
5992         _old_set->add(r);
5993       }
5994       _total_used += r->used();
5995     }
5996 
5997     return false;
5998   }
5999 
6000   size_t total_used() {
6001     return _total_used;
6002   }
6003 };
6004 
6005 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6006   assert_at_safepoint(true /* should_be_vm_thread */);
6007 
6008   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6009   heap_region_iterate(&cl);
6010 
6011   if (!free_list_only) {
6012     _summary_bytes_used = cl.total_used();
6013   }
6014   assert(_summary_bytes_used == recalculate_used(),
6015          err_msg("inconsistent _summary_bytes_used, "
6016                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6017                  _summary_bytes_used, recalculate_used()));
6018 }
6019 
6020 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6021   _refine_cte_cl->set_concurrent(concurrent);
6022 }
6023 
6024 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6025   HeapRegion* hr = heap_region_containing(p);
6026   if (hr == NULL) {
6027     return is_in_permanent(p);
6028   } else {
6029     return hr->is_in(p);
6030   }
6031 }
6032 
6033 // Methods for the mutator alloc region
6034 
6035 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6036                                                       bool force) {
6037   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6038   assert(!force || g1_policy()->can_expand_young_list(),
6039          "if force is true we should be able to expand the young list");
6040   bool young_list_full = g1_policy()->is_young_list_full();
6041   if (force || !young_list_full) {
6042     HeapRegion* new_alloc_region = new_region(word_size,
6043                                               false /* do_expand */);
6044     if (new_alloc_region != NULL) {
6045       set_region_short_lived_locked(new_alloc_region);
6046       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6047       return new_alloc_region;
6048     }
6049   }
6050   return NULL;
6051 }
6052 
6053 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6054                                                   size_t allocated_bytes) {
6055   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6056   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6057 
6058   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6059   _summary_bytes_used += allocated_bytes;
6060   _hr_printer.retire(alloc_region);
6061   // We update the eden sizes here, when the region is retired,
6062   // instead of when it's allocated, since this is the point that its
6063   // used space has been recored in _summary_bytes_used.
6064   g1mm()->update_eden_size();
6065 }
6066 
6067 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6068                                                     bool force) {
6069   return _g1h->new_mutator_alloc_region(word_size, force);
6070 }
6071 
6072 void G1CollectedHeap::set_par_threads() {
6073   // Don't change the number of workers.  Use the value previously set
6074   // in the workgroup.
6075   int n_workers = workers()->active_workers();
6076     assert(UseDynamicNumberOfGCThreads ||
6077            n_workers == workers()->total_workers(),
6078       "Otherwise should be using the total number of workers");
6079   if (n_workers == 0) {
6080     assert(false, "Should have been set in prior evacuation pause.");
6081     n_workers = ParallelGCThreads;
6082     workers()->set_active_workers(n_workers);
6083   }
6084   set_par_threads(n_workers);
6085 }
6086 
6087 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6088                                        size_t allocated_bytes) {
6089   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6090 }
6091 
6092 // Methods for the GC alloc regions
6093 
6094 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6095                                                  size_t count,
6096                                                  GCAllocPurpose ap) {
6097   assert(FreeList_lock->owned_by_self(), "pre-condition");
6098 
6099   if (count < g1_policy()->max_regions(ap)) {
6100     HeapRegion* new_alloc_region = new_region(word_size,
6101                                               true /* do_expand */);
6102     if (new_alloc_region != NULL) {
6103       // We really only need to do this for old regions given that we
6104       // should never scan survivors. But it doesn't hurt to do it
6105       // for survivors too.
6106       new_alloc_region->set_saved_mark();
6107       if (ap == GCAllocForSurvived) {
6108         new_alloc_region->set_survivor();
6109         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6110       } else {
6111         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6112       }
6113       return new_alloc_region;
6114     } else {
6115       g1_policy()->note_alloc_region_limit_reached(ap);
6116     }
6117   }
6118   return NULL;
6119 }
6120 
6121 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6122                                              size_t allocated_bytes,
6123                                              GCAllocPurpose ap) {
6124   alloc_region->note_end_of_copying();
6125   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6126   if (ap == GCAllocForSurvived) {
6127     young_list()->add_survivor_region(alloc_region);
6128   } else {
6129     _old_set.add(alloc_region);
6130   }
6131   _hr_printer.retire(alloc_region);
6132 }
6133 
6134 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6135                                                        bool force) {
6136   assert(!force, "not supported for GC alloc regions");
6137   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6138 }
6139 
6140 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6141                                           size_t allocated_bytes) {
6142   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6143                                GCAllocForSurvived);
6144 }
6145 
6146 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6147                                                   bool force) {
6148   assert(!force, "not supported for GC alloc regions");
6149   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6150 }
6151 
6152 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6153                                      size_t allocated_bytes) {
6154   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6155                                GCAllocForTenured);
6156 }
6157 // Heap region set verification
6158 
6159 class VerifyRegionListsClosure : public HeapRegionClosure {
6160 private:
6161   FreeRegionList*     _free_list;
6162   OldRegionSet*       _old_set;
6163   HumongousRegionSet* _humongous_set;
6164   size_t              _region_count;
6165 
6166 public:
6167   VerifyRegionListsClosure(OldRegionSet* old_set,
6168                            HumongousRegionSet* humongous_set,
6169                            FreeRegionList* free_list) :
6170     _old_set(old_set), _humongous_set(humongous_set),
6171     _free_list(free_list), _region_count(0) { }
6172 
6173   size_t region_count()      { return _region_count;      }
6174 
6175   bool doHeapRegion(HeapRegion* hr) {
6176     _region_count += 1;
6177 
6178     if (hr->continuesHumongous()) {
6179       return false;
6180     }
6181 
6182     if (hr->is_young()) {
6183       // TODO
6184     } else if (hr->startsHumongous()) {
6185       _humongous_set->verify_next_region(hr);
6186     } else if (hr->is_empty()) {
6187       _free_list->verify_next_region(hr);
6188     } else {
6189       _old_set->verify_next_region(hr);
6190     }
6191     return false;
6192   }
6193 };
6194 
6195 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index,
6196                                              HeapWord* bottom) {
6197   HeapWord* end = bottom + HeapRegion::GrainWords;
6198   MemRegion mr(bottom, end);
6199   assert(_g1_reserved.contains(mr), "invariant");
6200   // This might return NULL if the allocation fails
6201   return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6202 }
6203 
6204 void G1CollectedHeap::verify_region_sets() {
6205   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6206 
6207   // First, check the explicit lists.
6208   _free_list.verify();
6209   {
6210     // Given that a concurrent operation might be adding regions to
6211     // the secondary free list we have to take the lock before
6212     // verifying it.
6213     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6214     _secondary_free_list.verify();
6215   }
6216   _old_set.verify();
6217   _humongous_set.verify();
6218 
6219   // If a concurrent region freeing operation is in progress it will
6220   // be difficult to correctly attributed any free regions we come
6221   // across to the correct free list given that they might belong to
6222   // one of several (free_list, secondary_free_list, any local lists,
6223   // etc.). So, if that's the case we will skip the rest of the
6224   // verification operation. Alternatively, waiting for the concurrent
6225   // operation to complete will have a non-trivial effect on the GC's
6226   // operation (no concurrent operation will last longer than the
6227   // interval between two calls to verification) and it might hide
6228   // any issues that we would like to catch during testing.
6229   if (free_regions_coming()) {
6230     return;
6231   }
6232 
6233   // Make sure we append the secondary_free_list on the free_list so
6234   // that all free regions we will come across can be safely
6235   // attributed to the free_list.
6236   append_secondary_free_list_if_not_empty_with_lock();
6237 
6238   // Finally, make sure that the region accounting in the lists is
6239   // consistent with what we see in the heap.
6240   _old_set.verify_start();
6241   _humongous_set.verify_start();
6242   _free_list.verify_start();
6243 
6244   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6245   heap_region_iterate(&cl);
6246 
6247   _old_set.verify_end();
6248   _humongous_set.verify_end();
6249   _free_list.verify_end();
6250 }