1 /*
   2  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "code/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/g1EvacFailure.hpp"
  36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  37 #include "gc_implementation/g1/g1Log.hpp"
  38 #include "gc_implementation/g1/g1MarkSweep.hpp"
  39 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  40 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  41 #include "gc_implementation/g1/g1YCTypes.hpp"
  42 #include "gc_implementation/g1/heapRegion.inline.hpp"
  43 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  45 #include "gc_implementation/g1/vm_operations_g1.hpp"
  46 #include "gc_implementation/shared/gcHeapSummary.hpp"
  47 #include "gc_implementation/shared/gcTimer.hpp"
  48 #include "gc_implementation/shared/gcTrace.hpp"
  49 #include "gc_implementation/shared/gcTraceTime.hpp"
  50 #include "gc_implementation/shared/isGCActiveMark.hpp"
  51 #include "memory/gcLocker.inline.hpp"
  52 #include "memory/genOopClosures.inline.hpp"
  53 #include "memory/generationSpec.hpp"
  54 #include "memory/referenceProcessor.hpp"
  55 #include "oops/oop.inline.hpp"
  56 #include "oops/oop.pcgc.inline.hpp"
  57 #include "runtime/vmThread.hpp"
  58 
  59 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  60 
  61 // turn it on so that the contents of the young list (scan-only /
  62 // to-be-collected) are printed at "strategic" points before / during
  63 // / after the collection --- this is useful for debugging
  64 #define YOUNG_LIST_VERBOSE 0
  65 // CURRENT STATUS
  66 // This file is under construction.  Search for "FIXME".
  67 
  68 // INVARIANTS/NOTES
  69 //
  70 // All allocation activity covered by the G1CollectedHeap interface is
  71 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  72 // and allocate_new_tlab, which are the "entry" points to the
  73 // allocation code from the rest of the JVM.  (Note that this does not
  74 // apply to TLAB allocation, which is not part of this interface: it
  75 // is done by clients of this interface.)
  76 
  77 // Notes on implementation of parallelism in different tasks.
  78 //
  79 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  80 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  81 // It does use run_task() which sets _n_workers in the task.
  82 // G1ParTask executes g1_process_strong_roots() ->
  83 // SharedHeap::process_strong_roots() which calls eventually to
  84 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  85 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  86 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  87 //
  88 
  89 // Local to this file.
  90 
  91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  92   SuspendibleThreadSet* _sts;
  93   G1RemSet* _g1rs;
  94   ConcurrentG1Refine* _cg1r;
  95   bool _concurrent;
  96 public:
  97   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  98                               G1RemSet* g1rs,
  99                               ConcurrentG1Refine* cg1r) :
 100     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
 101   {}
 102   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 103     bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
 104     // This path is executed by the concurrent refine or mutator threads,
 105     // concurrently, and so we do not care if card_ptr contains references
 106     // that point into the collection set.
 107     assert(!oops_into_cset, "should be");
 108 
 109     if (_concurrent && _sts->should_yield()) {
 110       // Caller will actually yield.
 111       return false;
 112     }
 113     // Otherwise, we finished successfully; return true.
 114     return true;
 115   }
 116   void set_concurrent(bool b) { _concurrent = b; }
 117 };
 118 
 119 
 120 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 121   int _calls;
 122   G1CollectedHeap* _g1h;
 123   CardTableModRefBS* _ctbs;
 124   int _histo[256];
 125 public:
 126   ClearLoggedCardTableEntryClosure() :
 127     _calls(0)
 128   {
 129     _g1h = G1CollectedHeap::heap();
 130     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 131     for (int i = 0; i < 256; i++) _histo[i] = 0;
 132   }
 133   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 134     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 135       _calls++;
 136       unsigned char* ujb = (unsigned char*)card_ptr;
 137       int ind = (int)(*ujb);
 138       _histo[ind]++;
 139       *card_ptr = -1;
 140     }
 141     return true;
 142   }
 143   int calls() { return _calls; }
 144   void print_histo() {
 145     gclog_or_tty->print_cr("Card table value histogram:");
 146     for (int i = 0; i < 256; i++) {
 147       if (_histo[i] != 0) {
 148         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 149       }
 150     }
 151   }
 152 };
 153 
 154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 155   int _calls;
 156   G1CollectedHeap* _g1h;
 157   CardTableModRefBS* _ctbs;
 158 public:
 159   RedirtyLoggedCardTableEntryClosure() :
 160     _calls(0)
 161   {
 162     _g1h = G1CollectedHeap::heap();
 163     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 164   }
 165   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 166     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 167       _calls++;
 168       *card_ptr = 0;
 169     }
 170     return true;
 171   }
 172   int calls() { return _calls; }
 173 };
 174 
 175 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 176 public:
 177   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 178     *card_ptr = CardTableModRefBS::dirty_card_val();
 179     return true;
 180   }
 181 };
 182 
 183 YoungList::YoungList(G1CollectedHeap* g1h) :
 184     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 185     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 186   guarantee(check_list_empty(false), "just making sure...");
 187 }
 188 
 189 void YoungList::push_region(HeapRegion *hr) {
 190   assert(!hr->is_young(), "should not already be young");
 191   assert(hr->get_next_young_region() == NULL, "cause it should!");
 192 
 193   hr->set_next_young_region(_head);
 194   _head = hr;
 195 
 196   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 197   ++_length;
 198 }
 199 
 200 void YoungList::add_survivor_region(HeapRegion* hr) {
 201   assert(hr->is_survivor(), "should be flagged as survivor region");
 202   assert(hr->get_next_young_region() == NULL, "cause it should!");
 203 
 204   hr->set_next_young_region(_survivor_head);
 205   if (_survivor_head == NULL) {
 206     _survivor_tail = hr;
 207   }
 208   _survivor_head = hr;
 209   ++_survivor_length;
 210 }
 211 
 212 void YoungList::empty_list(HeapRegion* list) {
 213   while (list != NULL) {
 214     HeapRegion* next = list->get_next_young_region();
 215     list->set_next_young_region(NULL);
 216     list->uninstall_surv_rate_group();
 217     list->set_not_young();
 218     list = next;
 219   }
 220 }
 221 
 222 void YoungList::empty_list() {
 223   assert(check_list_well_formed(), "young list should be well formed");
 224 
 225   empty_list(_head);
 226   _head = NULL;
 227   _length = 0;
 228 
 229   empty_list(_survivor_head);
 230   _survivor_head = NULL;
 231   _survivor_tail = NULL;
 232   _survivor_length = 0;
 233 
 234   _last_sampled_rs_lengths = 0;
 235 
 236   assert(check_list_empty(false), "just making sure...");
 237 }
 238 
 239 bool YoungList::check_list_well_formed() {
 240   bool ret = true;
 241 
 242   uint length = 0;
 243   HeapRegion* curr = _head;
 244   HeapRegion* last = NULL;
 245   while (curr != NULL) {
 246     if (!curr->is_young()) {
 247       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 248                              "incorrectly tagged (y: %d, surv: %d)",
 249                              curr->bottom(), curr->end(),
 250                              curr->is_young(), curr->is_survivor());
 251       ret = false;
 252     }
 253     ++length;
 254     last = curr;
 255     curr = curr->get_next_young_region();
 256   }
 257   ret = ret && (length == _length);
 258 
 259   if (!ret) {
 260     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 261     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 262                            length, _length);
 263   }
 264 
 265   return ret;
 266 }
 267 
 268 bool YoungList::check_list_empty(bool check_sample) {
 269   bool ret = true;
 270 
 271   if (_length != 0) {
 272     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 273                   _length);
 274     ret = false;
 275   }
 276   if (check_sample && _last_sampled_rs_lengths != 0) {
 277     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 278     ret = false;
 279   }
 280   if (_head != NULL) {
 281     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 282     ret = false;
 283   }
 284   if (!ret) {
 285     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 286   }
 287 
 288   return ret;
 289 }
 290 
 291 void
 292 YoungList::rs_length_sampling_init() {
 293   _sampled_rs_lengths = 0;
 294   _curr               = _head;
 295 }
 296 
 297 bool
 298 YoungList::rs_length_sampling_more() {
 299   return _curr != NULL;
 300 }
 301 
 302 void
 303 YoungList::rs_length_sampling_next() {
 304   assert( _curr != NULL, "invariant" );
 305   size_t rs_length = _curr->rem_set()->occupied();
 306 
 307   _sampled_rs_lengths += rs_length;
 308 
 309   // The current region may not yet have been added to the
 310   // incremental collection set (it gets added when it is
 311   // retired as the current allocation region).
 312   if (_curr->in_collection_set()) {
 313     // Update the collection set policy information for this region
 314     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 315   }
 316 
 317   _curr = _curr->get_next_young_region();
 318   if (_curr == NULL) {
 319     _last_sampled_rs_lengths = _sampled_rs_lengths;
 320     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 321   }
 322 }
 323 
 324 void
 325 YoungList::reset_auxilary_lists() {
 326   guarantee( is_empty(), "young list should be empty" );
 327   assert(check_list_well_formed(), "young list should be well formed");
 328 
 329   // Add survivor regions to SurvRateGroup.
 330   _g1h->g1_policy()->note_start_adding_survivor_regions();
 331   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 332 
 333   int young_index_in_cset = 0;
 334   for (HeapRegion* curr = _survivor_head;
 335        curr != NULL;
 336        curr = curr->get_next_young_region()) {
 337     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 338 
 339     // The region is a non-empty survivor so let's add it to
 340     // the incremental collection set for the next evacuation
 341     // pause.
 342     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 343     young_index_in_cset += 1;
 344   }
 345   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 346   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 347 
 348   _head   = _survivor_head;
 349   _length = _survivor_length;
 350   if (_survivor_head != NULL) {
 351     assert(_survivor_tail != NULL, "cause it shouldn't be");
 352     assert(_survivor_length > 0, "invariant");
 353     _survivor_tail->set_next_young_region(NULL);
 354   }
 355 
 356   // Don't clear the survivor list handles until the start of
 357   // the next evacuation pause - we need it in order to re-tag
 358   // the survivor regions from this evacuation pause as 'young'
 359   // at the start of the next.
 360 
 361   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 362 
 363   assert(check_list_well_formed(), "young list should be well formed");
 364 }
 365 
 366 void YoungList::print() {
 367   HeapRegion* lists[] = {_head,   _survivor_head};
 368   const char* names[] = {"YOUNG", "SURVIVOR"};
 369 
 370   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 371     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 372     HeapRegion *curr = lists[list];
 373     if (curr == NULL)
 374       gclog_or_tty->print_cr("  empty");
 375     while (curr != NULL) {
 376       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 377                              HR_FORMAT_PARAMS(curr),
 378                              curr->prev_top_at_mark_start(),
 379                              curr->next_top_at_mark_start(),
 380                              curr->age_in_surv_rate_group_cond());
 381       curr = curr->get_next_young_region();
 382     }
 383   }
 384 
 385   gclog_or_tty->print_cr("");
 386 }
 387 
 388 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 389 {
 390   // Claim the right to put the region on the dirty cards region list
 391   // by installing a self pointer.
 392   HeapRegion* next = hr->get_next_dirty_cards_region();
 393   if (next == NULL) {
 394     HeapRegion* res = (HeapRegion*)
 395       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 396                           NULL);
 397     if (res == NULL) {
 398       HeapRegion* head;
 399       do {
 400         // Put the region to the dirty cards region list.
 401         head = _dirty_cards_region_list;
 402         next = (HeapRegion*)
 403           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 404         if (next == head) {
 405           assert(hr->get_next_dirty_cards_region() == hr,
 406                  "hr->get_next_dirty_cards_region() != hr");
 407           if (next == NULL) {
 408             // The last region in the list points to itself.
 409             hr->set_next_dirty_cards_region(hr);
 410           } else {
 411             hr->set_next_dirty_cards_region(next);
 412           }
 413         }
 414       } while (next != head);
 415     }
 416   }
 417 }
 418 
 419 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 420 {
 421   HeapRegion* head;
 422   HeapRegion* hr;
 423   do {
 424     head = _dirty_cards_region_list;
 425     if (head == NULL) {
 426       return NULL;
 427     }
 428     HeapRegion* new_head = head->get_next_dirty_cards_region();
 429     if (head == new_head) {
 430       // The last region.
 431       new_head = NULL;
 432     }
 433     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 434                                           head);
 435   } while (hr != head);
 436   assert(hr != NULL, "invariant");
 437   hr->set_next_dirty_cards_region(NULL);
 438   return hr;
 439 }
 440 
 441 void G1CollectedHeap::stop_conc_gc_threads() {
 442   _cg1r->stop();
 443   _cmThread->stop();
 444 }
 445 
 446 #ifdef ASSERT
 447 // A region is added to the collection set as it is retired
 448 // so an address p can point to a region which will be in the
 449 // collection set but has not yet been retired.  This method
 450 // therefore is only accurate during a GC pause after all
 451 // regions have been retired.  It is used for debugging
 452 // to check if an nmethod has references to objects that can
 453 // be move during a partial collection.  Though it can be
 454 // inaccurate, it is sufficient for G1 because the conservative
 455 // implementation of is_scavengable() for G1 will indicate that
 456 // all nmethods must be scanned during a partial collection.
 457 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 458   HeapRegion* hr = heap_region_containing(p);
 459   return hr != NULL && hr->in_collection_set();
 460 }
 461 #endif
 462 
 463 // Returns true if the reference points to an object that
 464 // can move in an incremental collection.
 465 bool G1CollectedHeap::is_scavengable(const void* p) {
 466   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 467   G1CollectorPolicy* g1p = g1h->g1_policy();
 468   HeapRegion* hr = heap_region_containing(p);
 469   if (hr == NULL) {
 470      // null
 471      assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
 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 %u 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 notified 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 && _expand_heap_after_alloc_failure) {
 595     // Currently, only attempts to allocate GC alloc regions set
 596     // do_expand to true. So, we should only reach here during a
 597     // safepoint. If this assumption changes we might have to
 598     // reconsider the use of _expand_heap_after_alloc_failure.
 599     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 600 
 601     ergo_verbose1(ErgoHeapSizing,
 602                   "attempt heap expansion",
 603                   ergo_format_reason("region allocation request failed")
 604                   ergo_format_byte("allocation request"),
 605                   word_size * HeapWordSize);
 606     if (expand(word_size * HeapWordSize)) {
 607       // Given that expand() succeeded in expanding the heap, and we
 608       // always expand the heap by an amount aligned to the heap
 609       // region size, the free list should in theory not be empty. So
 610       // it would probably be OK to use remove_head(). But the extra
 611       // check for NULL is unlikely to be a performance issue here (we
 612       // just expanded the heap!) so let's just be conservative and
 613       // use remove_head_or_null().
 614       res = _free_list.remove_head_or_null();
 615     } else {
 616       _expand_heap_after_alloc_failure = false;
 617     }
 618   }
 619   return res;
 620 }
 621 
 622 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 623                                                         size_t word_size) {
 624   assert(isHumongous(word_size), "word_size should be humongous");
 625   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 626 
 627   uint first = G1_NULL_HRS_INDEX;
 628   if (num_regions == 1) {
 629     // Only one region to allocate, no need to go through the slower
 630     // path. The caller will attempt the expansion if this fails, so
 631     // let's not try to expand here too.
 632     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 633     if (hr != NULL) {
 634       first = hr->hrs_index();
 635     } else {
 636       first = G1_NULL_HRS_INDEX;
 637     }
 638   } else {
 639     // We can't allocate humongous regions while cleanupComplete() is
 640     // running, since some of the regions we find to be empty might not
 641     // yet be added to the free list and it is not straightforward to
 642     // know which list they are on so that we can remove them. Note
 643     // that we only need to do this if we need to allocate more than
 644     // one region to satisfy the current humongous allocation
 645     // request. If we are only allocating one region we use the common
 646     // region allocation code (see above).
 647     wait_while_free_regions_coming();
 648     append_secondary_free_list_if_not_empty_with_lock();
 649 
 650     if (free_regions() >= num_regions) {
 651       first = _hrs.find_contiguous(num_regions);
 652       if (first != G1_NULL_HRS_INDEX) {
 653         for (uint i = first; i < first + num_regions; ++i) {
 654           HeapRegion* hr = region_at(i);
 655           assert(hr->is_empty(), "sanity");
 656           assert(is_on_master_free_list(hr), "sanity");
 657           hr->set_pending_removal(true);
 658         }
 659         _free_list.remove_all_pending(num_regions);
 660       }
 661     }
 662   }
 663   return first;
 664 }
 665 
 666 HeapWord*
 667 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 668                                                            uint num_regions,
 669                                                            size_t word_size) {
 670   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 671   assert(isHumongous(word_size), "word_size should be humongous");
 672   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 673 
 674   // Index of last region in the series + 1.
 675   uint last = first + num_regions;
 676 
 677   // We need to initialize the region(s) we just discovered. This is
 678   // a bit tricky given that it can happen concurrently with
 679   // refinement threads refining cards on these regions and
 680   // potentially wanting to refine the BOT as they are scanning
 681   // those cards (this can happen shortly after a cleanup; see CR
 682   // 6991377). So we have to set up the region(s) carefully and in
 683   // a specific order.
 684 
 685   // The word size sum of all the regions we will allocate.
 686   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 687   assert(word_size <= word_size_sum, "sanity");
 688 
 689   // This will be the "starts humongous" region.
 690   HeapRegion* first_hr = region_at(first);
 691   // The header of the new object will be placed at the bottom of
 692   // the first region.
 693   HeapWord* new_obj = first_hr->bottom();
 694   // This will be the new end of the first region in the series that
 695   // should also match the end of the last region in the series.
 696   HeapWord* new_end = new_obj + word_size_sum;
 697   // This will be the new top of the first region that will reflect
 698   // this allocation.
 699   HeapWord* new_top = new_obj + word_size;
 700 
 701   // First, we need to zero the header of the space that we will be
 702   // allocating. When we update top further down, some refinement
 703   // threads might try to scan the region. By zeroing the header we
 704   // ensure that any thread that will try to scan the region will
 705   // come across the zero klass word and bail out.
 706   //
 707   // NOTE: It would not have been correct to have used
 708   // CollectedHeap::fill_with_object() and make the space look like
 709   // an int array. The thread that is doing the allocation will
 710   // later update the object header to a potentially different array
 711   // type and, for a very short period of time, the klass and length
 712   // fields will be inconsistent. This could cause a refinement
 713   // thread to calculate the object size incorrectly.
 714   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 715 
 716   // We will set up the first region as "starts humongous". This
 717   // will also update the BOT covering all the regions to reflect
 718   // that there is a single object that starts at the bottom of the
 719   // first region.
 720   first_hr->set_startsHumongous(new_top, new_end);
 721 
 722   // Then, if there are any, we will set up the "continues
 723   // humongous" regions.
 724   HeapRegion* hr = NULL;
 725   for (uint i = first + 1; i < last; ++i) {
 726     hr = region_at(i);
 727     hr->set_continuesHumongous(first_hr);
 728   }
 729   // If we have "continues humongous" regions (hr != NULL), then the
 730   // end of the last one should match new_end.
 731   assert(hr == NULL || hr->end() == new_end, "sanity");
 732 
 733   // Up to this point no concurrent thread would have been able to
 734   // do any scanning on any region in this series. All the top
 735   // fields still point to bottom, so the intersection between
 736   // [bottom,top] and [card_start,card_end] will be empty. Before we
 737   // update the top fields, we'll do a storestore to make sure that
 738   // no thread sees the update to top before the zeroing of the
 739   // object header and the BOT initialization.
 740   OrderAccess::storestore();
 741 
 742   // Now that the BOT and the object header have been initialized,
 743   // we can update top of the "starts humongous" region.
 744   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 745          "new_top should be in this region");
 746   first_hr->set_top(new_top);
 747   if (_hr_printer.is_active()) {
 748     HeapWord* bottom = first_hr->bottom();
 749     HeapWord* end = first_hr->orig_end();
 750     if ((first + 1) == last) {
 751       // the series has a single humongous region
 752       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 753     } else {
 754       // the series has more than one humongous regions
 755       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 756     }
 757   }
 758 
 759   // Now, we will update the top fields of the "continues humongous"
 760   // regions. The reason we need to do this is that, otherwise,
 761   // these regions would look empty and this will confuse parts of
 762   // G1. For example, the code that looks for a consecutive number
 763   // of empty regions will consider them empty and try to
 764   // re-allocate them. We can extend is_empty() to also include
 765   // !continuesHumongous(), but it is easier to just update the top
 766   // fields here. The way we set top for all regions (i.e., top ==
 767   // end for all regions but the last one, top == new_top for the
 768   // last one) is actually used when we will free up the humongous
 769   // region in free_humongous_region().
 770   hr = NULL;
 771   for (uint i = first + 1; i < last; ++i) {
 772     hr = region_at(i);
 773     if ((i + 1) == last) {
 774       // last continues humongous region
 775       assert(hr->bottom() < new_top && new_top <= hr->end(),
 776              "new_top should fall on this region");
 777       hr->set_top(new_top);
 778       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 779     } else {
 780       // not last one
 781       assert(new_top > hr->end(), "new_top should be above this region");
 782       hr->set_top(hr->end());
 783       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 784     }
 785   }
 786   // If we have continues humongous regions (hr != NULL), then the
 787   // end of the last one should match new_end and its top should
 788   // match new_top.
 789   assert(hr == NULL ||
 790          (hr->end() == new_end && hr->top() == new_top), "sanity");
 791 
 792   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 793   _summary_bytes_used += first_hr->used();
 794   _humongous_set.add(first_hr);
 795 
 796   return new_obj;
 797 }
 798 
 799 // If could fit into free regions w/o expansion, try.
 800 // Otherwise, if can expand, do so.
 801 // Otherwise, if using ex regions might help, try with ex given back.
 802 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 803   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 804 
 805   verify_region_sets_optional();
 806 
 807   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 808   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 809   uint x_num = expansion_regions();
 810   uint fs = _hrs.free_suffix();
 811   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 812   if (first == G1_NULL_HRS_INDEX) {
 813     // The only thing we can do now is attempt expansion.
 814     if (fs + x_num >= num_regions) {
 815       // If the number of regions we're trying to allocate for this
 816       // object is at most the number of regions in the free suffix,
 817       // then the call to humongous_obj_allocate_find_first() above
 818       // should have succeeded and we wouldn't be here.
 819       //
 820       // We should only be trying to expand when the free suffix is
 821       // not sufficient for the object _and_ we have some expansion
 822       // room available.
 823       assert(num_regions > fs, "earlier allocation should have succeeded");
 824 
 825       ergo_verbose1(ErgoHeapSizing,
 826                     "attempt heap expansion",
 827                     ergo_format_reason("humongous allocation request failed")
 828                     ergo_format_byte("allocation request"),
 829                     word_size * HeapWordSize);
 830       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 831         // Even though the heap was expanded, it might not have
 832         // reached the desired size. So, we cannot assume that the
 833         // allocation will succeed.
 834         first = humongous_obj_allocate_find_first(num_regions, word_size);
 835       }
 836     }
 837   }
 838 
 839   HeapWord* result = NULL;
 840   if (first != G1_NULL_HRS_INDEX) {
 841     result =
 842       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 843     assert(result != NULL, "it should always return a valid result");
 844 
 845     // A successful humongous object allocation changes the used space
 846     // information of the old generation so we need to recalculate the
 847     // sizes and update the jstat counters here.
 848     g1mm()->update_sizes();
 849   }
 850 
 851   verify_region_sets_optional();
 852 
 853   return result;
 854 }
 855 
 856 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 857   assert_heap_not_locked_and_not_at_safepoint();
 858   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 859 
 860   unsigned int dummy_gc_count_before;
 861   int dummy_gclocker_retry_count = 0;
 862   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 863 }
 864 
 865 HeapWord*
 866 G1CollectedHeap::mem_allocate(size_t word_size,
 867                               bool*  gc_overhead_limit_was_exceeded) {
 868   assert_heap_not_locked_and_not_at_safepoint();
 869 
 870   // Loop until the allocation is satisfied, or unsatisfied after GC.
 871   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 872     unsigned int gc_count_before;
 873 
 874     HeapWord* result = NULL;
 875     if (!isHumongous(word_size)) {
 876       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 877     } else {
 878       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 879     }
 880     if (result != NULL) {
 881       return result;
 882     }
 883 
 884     // Create the garbage collection operation...
 885     VM_G1CollectForAllocation op(gc_count_before, word_size);
 886     // ...and get the VM thread to execute it.
 887     VMThread::execute(&op);
 888 
 889     if (op.prologue_succeeded() && op.pause_succeeded()) {
 890       // If the operation was successful we'll return the result even
 891       // if it is NULL. If the allocation attempt failed immediately
 892       // after a Full GC, it's unlikely we'll be able to allocate now.
 893       HeapWord* result = op.result();
 894       if (result != NULL && !isHumongous(word_size)) {
 895         // Allocations that take place on VM operations do not do any
 896         // card dirtying and we have to do it here. We only have to do
 897         // this for non-humongous allocations, though.
 898         dirty_young_block(result, word_size);
 899       }
 900       return result;
 901     } else {
 902       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 903         return NULL;
 904       }
 905       assert(op.result() == NULL,
 906              "the result should be NULL if the VM op did not succeed");
 907     }
 908 
 909     // Give a warning if we seem to be looping forever.
 910     if ((QueuedAllocationWarningCount > 0) &&
 911         (try_count % QueuedAllocationWarningCount == 0)) {
 912       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 913     }
 914   }
 915 
 916   ShouldNotReachHere();
 917   return NULL;
 918 }
 919 
 920 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 921                                            unsigned int *gc_count_before_ret,
 922                                            int* gclocker_retry_count_ret) {
 923   // Make sure you read the note in attempt_allocation_humongous().
 924 
 925   assert_heap_not_locked_and_not_at_safepoint();
 926   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 927          "be called for humongous allocation requests");
 928 
 929   // We should only get here after the first-level allocation attempt
 930   // (attempt_allocation()) failed to allocate.
 931 
 932   // We will loop until a) we manage to successfully perform the
 933   // allocation or b) we successfully schedule a collection which
 934   // fails to perform the allocation. b) is the only case when we'll
 935   // return NULL.
 936   HeapWord* result = NULL;
 937   for (int try_count = 1; /* we'll return */; try_count += 1) {
 938     bool should_try_gc;
 939     unsigned int gc_count_before;
 940 
 941     {
 942       MutexLockerEx x(Heap_lock);
 943 
 944       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 945                                                       false /* bot_updates */);
 946       if (result != NULL) {
 947         return result;
 948       }
 949 
 950       // If we reach here, attempt_allocation_locked() above failed to
 951       // allocate a new region. So the mutator alloc region should be NULL.
 952       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 953 
 954       if (GC_locker::is_active_and_needs_gc()) {
 955         if (g1_policy()->can_expand_young_list()) {
 956           // No need for an ergo verbose message here,
 957           // can_expand_young_list() does this when it returns true.
 958           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 959                                                       false /* bot_updates */);
 960           if (result != NULL) {
 961             return result;
 962           }
 963         }
 964         should_try_gc = false;
 965       } else {
 966         // The GCLocker may not be active but the GCLocker initiated
 967         // GC may not yet have been performed (GCLocker::needs_gc()
 968         // returns true). In this case we do not try this GC and
 969         // wait until the GCLocker initiated GC is performed, and
 970         // then retry the allocation.
 971         if (GC_locker::needs_gc()) {
 972           should_try_gc = false;
 973         } else {
 974           // Read the GC count while still holding the Heap_lock.
 975           gc_count_before = total_collections();
 976           should_try_gc = true;
 977         }
 978       }
 979     }
 980 
 981     if (should_try_gc) {
 982       bool succeeded;
 983       result = do_collection_pause(word_size, gc_count_before, &succeeded);
 984       if (result != NULL) {
 985         assert(succeeded, "only way to get back a non-NULL result");
 986         return result;
 987       }
 988 
 989       if (succeeded) {
 990         // If we get here we successfully scheduled a collection which
 991         // failed to allocate. No point in trying to allocate
 992         // further. We'll just return NULL.
 993         MutexLockerEx x(Heap_lock);
 994         *gc_count_before_ret = total_collections();
 995         return NULL;
 996       }
 997     } else {
 998       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 999         MutexLockerEx x(Heap_lock);
1000         *gc_count_before_ret = total_collections();
1001         return NULL;
1002       }
1003       // The GCLocker is either active or the GCLocker initiated
1004       // GC has not yet been performed. Stall until it is and
1005       // then retry the allocation.
1006       GC_locker::stall_until_clear();
1007       (*gclocker_retry_count_ret) += 1;
1008     }
1009 
1010     // We can reach here if we were unsuccessful in scheduling a
1011     // collection (because another thread beat us to it) or if we were
1012     // stalled due to the GC locker. In either can we should retry the
1013     // allocation attempt in case another thread successfully
1014     // performed a collection and reclaimed enough space. We do the
1015     // first attempt (without holding the Heap_lock) here and the
1016     // follow-on attempt will be at the start of the next loop
1017     // iteration (after taking the Heap_lock).
1018     result = _mutator_alloc_region.attempt_allocation(word_size,
1019                                                       false /* bot_updates */);
1020     if (result != NULL) {
1021       return result;
1022     }
1023 
1024     // Give a warning if we seem to be looping forever.
1025     if ((QueuedAllocationWarningCount > 0) &&
1026         (try_count % QueuedAllocationWarningCount == 0)) {
1027       warning("G1CollectedHeap::attempt_allocation_slow() "
1028               "retries %d times", try_count);
1029     }
1030   }
1031 
1032   ShouldNotReachHere();
1033   return NULL;
1034 }
1035 
1036 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1037                                           unsigned int * gc_count_before_ret,
1038                                           int* gclocker_retry_count_ret) {
1039   // The structure of this method has a lot of similarities to
1040   // attempt_allocation_slow(). The reason these two were not merged
1041   // into a single one is that such a method would require several "if
1042   // allocation is not humongous do this, otherwise do that"
1043   // conditional paths which would obscure its flow. In fact, an early
1044   // version of this code did use a unified method which was harder to
1045   // follow and, as a result, it had subtle bugs that were hard to
1046   // track down. So keeping these two methods separate allows each to
1047   // be more readable. It will be good to keep these two in sync as
1048   // much as possible.
1049 
1050   assert_heap_not_locked_and_not_at_safepoint();
1051   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1052          "should only be called for humongous allocations");
1053 
1054   // Humongous objects can exhaust the heap quickly, so we should check if we
1055   // need to start a marking cycle at each humongous object allocation. We do
1056   // the check before we do the actual allocation. The reason for doing it
1057   // before the allocation is that we avoid having to keep track of the newly
1058   // allocated memory while we do a GC.
1059   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1060                                            word_size)) {
1061     collect(GCCause::_g1_humongous_allocation);
1062   }
1063 
1064   // We will loop until a) we manage to successfully perform the
1065   // allocation or b) we successfully schedule a collection which
1066   // fails to perform the allocation. b) is the only case when we'll
1067   // return NULL.
1068   HeapWord* result = NULL;
1069   for (int try_count = 1; /* we'll return */; try_count += 1) {
1070     bool should_try_gc;
1071     unsigned int gc_count_before;
1072 
1073     {
1074       MutexLockerEx x(Heap_lock);
1075 
1076       // Given that humongous objects are not allocated in young
1077       // regions, we'll first try to do the allocation without doing a
1078       // collection hoping that there's enough space in the heap.
1079       result = humongous_obj_allocate(word_size);
1080       if (result != NULL) {
1081         return result;
1082       }
1083 
1084       if (GC_locker::is_active_and_needs_gc()) {
1085         should_try_gc = false;
1086       } else {
1087          // The GCLocker may not be active but the GCLocker initiated
1088         // GC may not yet have been performed (GCLocker::needs_gc()
1089         // returns true). In this case we do not try this GC and
1090         // wait until the GCLocker initiated GC is performed, and
1091         // then retry the allocation.
1092         if (GC_locker::needs_gc()) {
1093           should_try_gc = false;
1094         } else {
1095           // Read the GC count while still holding the Heap_lock.
1096           gc_count_before = total_collections();
1097           should_try_gc = true;
1098         }
1099       }
1100     }
1101 
1102     if (should_try_gc) {
1103       // If we failed to allocate the humongous object, we should try to
1104       // do a collection pause (if we're allowed) in case it reclaims
1105       // enough space for the allocation to succeed after the pause.
1106 
1107       bool succeeded;
1108       result = do_collection_pause(word_size, gc_count_before, &succeeded);
1109       if (result != NULL) {
1110         assert(succeeded, "only way to get back a non-NULL result");
1111         return result;
1112       }
1113 
1114       if (succeeded) {
1115         // If we get here we successfully scheduled a collection which
1116         // failed to allocate. No point in trying to allocate
1117         // further. We'll just return NULL.
1118         MutexLockerEx x(Heap_lock);
1119         *gc_count_before_ret = total_collections();
1120         return NULL;
1121       }
1122     } else {
1123       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1124         MutexLockerEx x(Heap_lock);
1125         *gc_count_before_ret = total_collections();
1126         return NULL;
1127       }
1128       // The GCLocker is either active or the GCLocker initiated
1129       // GC has not yet been performed. Stall until it is and
1130       // then retry the allocation.
1131       GC_locker::stall_until_clear();
1132       (*gclocker_retry_count_ret) += 1;
1133     }
1134 
1135     // We can reach here if we were unsuccessful in scheduling a
1136     // collection (because another thread beat us to it) or if we were
1137     // stalled due to the GC locker. In either can we should retry the
1138     // allocation attempt in case another thread successfully
1139     // performed a collection and reclaimed enough space.  Give a
1140     // warning if we seem to be looping forever.
1141 
1142     if ((QueuedAllocationWarningCount > 0) &&
1143         (try_count % QueuedAllocationWarningCount == 0)) {
1144       warning("G1CollectedHeap::attempt_allocation_humongous() "
1145               "retries %d times", try_count);
1146     }
1147   }
1148 
1149   ShouldNotReachHere();
1150   return NULL;
1151 }
1152 
1153 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1154                                        bool expect_null_mutator_alloc_region) {
1155   assert_at_safepoint(true /* should_be_vm_thread */);
1156   assert(_mutator_alloc_region.get() == NULL ||
1157                                              !expect_null_mutator_alloc_region,
1158          "the current alloc region was unexpectedly found to be non-NULL");
1159 
1160   if (!isHumongous(word_size)) {
1161     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1162                                                       false /* bot_updates */);
1163   } else {
1164     HeapWord* result = humongous_obj_allocate(word_size);
1165     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1166       g1_policy()->set_initiate_conc_mark_if_possible();
1167     }
1168     return result;
1169   }
1170 
1171   ShouldNotReachHere();
1172 }
1173 
1174 class PostMCRemSetClearClosure: public HeapRegionClosure {
1175   G1CollectedHeap* _g1h;
1176   ModRefBarrierSet* _mr_bs;
1177 public:
1178   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1179     _g1h(g1h), _mr_bs(mr_bs) { }
1180   bool doHeapRegion(HeapRegion* r) {
1181     if (r->continuesHumongous()) {
1182       return false;
1183     }
1184     _g1h->reset_gc_time_stamps(r);
1185     HeapRegionRemSet* hrrs = r->rem_set();
1186     if (hrrs != NULL) hrrs->clear();
1187     // You might think here that we could clear just the cards
1188     // corresponding to the used region.  But no: if we leave a dirty card
1189     // in a region we might allocate into, then it would prevent that card
1190     // from being enqueued, and cause it to be missed.
1191     // Re: the performance cost: we shouldn't be doing full GC anyway!
1192     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1193     return false;
1194   }
1195 };
1196 
1197 void G1CollectedHeap::clear_rsets_post_compaction() {
1198   PostMCRemSetClearClosure rs_clear(this, mr_bs());
1199   heap_region_iterate(&rs_clear);
1200 }
1201 
1202 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1203   G1CollectedHeap*   _g1h;
1204   UpdateRSOopClosure _cl;
1205   int                _worker_i;
1206 public:
1207   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1208     _cl(g1->g1_rem_set(), worker_i),
1209     _worker_i(worker_i),
1210     _g1h(g1)
1211   { }
1212 
1213   bool doHeapRegion(HeapRegion* r) {
1214     if (!r->continuesHumongous()) {
1215       _cl.set_from(r);
1216       r->oop_iterate(&_cl);
1217     }
1218     return false;
1219   }
1220 };
1221 
1222 class ParRebuildRSTask: public AbstractGangTask {
1223   G1CollectedHeap* _g1;
1224 public:
1225   ParRebuildRSTask(G1CollectedHeap* g1)
1226     : AbstractGangTask("ParRebuildRSTask"),
1227       _g1(g1)
1228   { }
1229 
1230   void work(uint worker_id) {
1231     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1232     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1233                                           _g1->workers()->active_workers(),
1234                                          HeapRegion::RebuildRSClaimValue);
1235   }
1236 };
1237 
1238 class PostCompactionPrinterClosure: public HeapRegionClosure {
1239 private:
1240   G1HRPrinter* _hr_printer;
1241 public:
1242   bool doHeapRegion(HeapRegion* hr) {
1243     assert(!hr->is_young(), "not expecting to find young regions");
1244     // We only generate output for non-empty regions.
1245     if (!hr->is_empty()) {
1246       if (!hr->isHumongous()) {
1247         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1248       } else if (hr->startsHumongous()) {
1249         if (hr->region_num() == 1) {
1250           // single humongous region
1251           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1252         } else {
1253           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1254         }
1255       } else {
1256         assert(hr->continuesHumongous(), "only way to get here");
1257         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1258       }
1259     }
1260     return false;
1261   }
1262 
1263   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1264     : _hr_printer(hr_printer) { }
1265 };
1266 
1267 void G1CollectedHeap::print_hrs_post_compaction() {
1268   PostCompactionPrinterClosure cl(hr_printer());
1269   heap_region_iterate(&cl);
1270 }
1271 
1272 double G1CollectedHeap::verify(bool guard, const char* msg) {
1273   double verify_time_ms = 0.0;
1274 
1275   if (guard && total_collections() >= VerifyGCStartAt) {
1276     double verify_start = os::elapsedTime();
1277     HandleMark hm;  // Discard invalid handles created during verification
1278     prepare_for_verify();
1279     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
1280     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
1281   }
1282 
1283   return verify_time_ms;
1284 }
1285 
1286 void G1CollectedHeap::verify_before_gc() {
1287   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
1288   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
1289 }
1290 
1291 void G1CollectedHeap::verify_after_gc() {
1292   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
1293   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
1294 }
1295 
1296 bool G1CollectedHeap::do_collection(bool explicit_gc,
1297                                     bool clear_all_soft_refs,
1298                                     size_t word_size) {
1299   assert_at_safepoint(true /* should_be_vm_thread */);
1300 
1301   if (GC_locker::check_active_before_gc()) {
1302     return false;
1303   }
1304 
1305   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1306   gc_timer->register_gc_start(os::elapsed_counter());
1307 
1308   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1309   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1310 
1311   SvcGCMarker sgcm(SvcGCMarker::FULL);
1312   ResourceMark rm;
1313 
1314   print_heap_before_gc();
1315   trace_heap_before_gc(gc_tracer);
1316 
1317   size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1318 
1319   HRSPhaseSetter x(HRSPhaseFullGC);
1320   verify_region_sets_optional();
1321 
1322   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1323                            collector_policy()->should_clear_all_soft_refs();
1324 
1325   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1326 
1327   {
1328     IsGCActiveMark x;
1329 
1330     // Timing
1331     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1332     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1333     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1334 
1335     {
1336       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1337       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1338       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1339 
1340       double start = os::elapsedTime();
1341       g1_policy()->record_full_collection_start();
1342 
1343       // Note: When we have a more flexible GC logging framework that
1344       // allows us to add optional attributes to a GC log record we
1345       // could consider timing and reporting how long we wait in the
1346       // following two methods.
1347       wait_while_free_regions_coming();
1348       // If we start the compaction before the CM threads finish
1349       // scanning the root regions we might trip them over as we'll
1350       // be moving objects / updating references. So let's wait until
1351       // they are done. By telling them to abort, they should complete
1352       // early.
1353       _cm->root_regions()->abort();
1354       _cm->root_regions()->wait_until_scan_finished();
1355       append_secondary_free_list_if_not_empty_with_lock();
1356 
1357       gc_prologue(true);
1358       increment_total_collections(true /* full gc */);
1359       increment_old_marking_cycles_started();
1360 
1361       assert(used() == recalculate_used(), "Should be equal");
1362 
1363       verify_before_gc();
1364 
1365       pre_full_gc_dump(gc_timer);
1366 
1367       COMPILER2_PRESENT(DerivedPointerTable::clear());
1368 
1369       // Disable discovery and empty the discovered lists
1370       // for the CM ref processor.
1371       ref_processor_cm()->disable_discovery();
1372       ref_processor_cm()->abandon_partial_discovery();
1373       ref_processor_cm()->verify_no_references_recorded();
1374 
1375       // Abandon current iterations of concurrent marking and concurrent
1376       // refinement, if any are in progress. We have to do this before
1377       // wait_until_scan_finished() below.
1378       concurrent_mark()->abort();
1379 
1380       // Make sure we'll choose a new allocation region afterwards.
1381       release_mutator_alloc_region();
1382       abandon_gc_alloc_regions();
1383       g1_rem_set()->cleanupHRRS();
1384 
1385       // We should call this after we retire any currently active alloc
1386       // regions so that all the ALLOC / RETIRE events are generated
1387       // before the start GC event.
1388       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1389 
1390       // We may have added regions to the current incremental collection
1391       // set between the last GC or pause and now. We need to clear the
1392       // incremental collection set and then start rebuilding it afresh
1393       // after this full GC.
1394       abandon_collection_set(g1_policy()->inc_cset_head());
1395       g1_policy()->clear_incremental_cset();
1396       g1_policy()->stop_incremental_cset_building();
1397 
1398       tear_down_region_sets(false /* free_list_only */);
1399       g1_policy()->set_gcs_are_young(true);
1400 
1401       // See the comments in g1CollectedHeap.hpp and
1402       // G1CollectedHeap::ref_processing_init() about
1403       // how reference processing currently works in G1.
1404 
1405       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1406       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1407 
1408       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1409       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1410 
1411       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1412       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1413 
1414       // Do collection work
1415       {
1416         HandleMark hm;  // Discard invalid handles created during gc
1417         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1418       }
1419 
1420       assert(free_regions() == 0, "we should not have added any free regions");
1421       rebuild_region_sets(false /* free_list_only */);
1422 
1423       // Enqueue any discovered reference objects that have
1424       // not been removed from the discovered lists.
1425       ref_processor_stw()->enqueue_discovered_references();
1426 
1427       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1428 
1429       MemoryService::track_memory_usage();
1430 
1431       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1432       ref_processor_stw()->verify_no_references_recorded();
1433 
1434       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1435       ClassLoaderDataGraph::purge();
1436     MetaspaceAux::verify_metrics();
1437 
1438       // Note: since we've just done a full GC, concurrent
1439       // marking is no longer active. Therefore we need not
1440       // re-enable reference discovery for the CM ref processor.
1441       // That will be done at the start of the next marking cycle.
1442       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1443       ref_processor_cm()->verify_no_references_recorded();
1444 
1445       reset_gc_time_stamp();
1446       // Since everything potentially moved, we will clear all remembered
1447       // sets, and clear all cards.  Later we will rebuild remembered
1448       // sets. We will also reset the GC time stamps of the regions.
1449       clear_rsets_post_compaction();
1450       check_gc_time_stamps();
1451 
1452       // Resize the heap if necessary.
1453       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1454 
1455       if (_hr_printer.is_active()) {
1456         // We should do this after we potentially resize the heap so
1457         // that all the COMMIT / UNCOMMIT events are generated before
1458         // the end GC event.
1459 
1460         print_hrs_post_compaction();
1461         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1462       }
1463 
1464       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1465       if (hot_card_cache->use_cache()) {
1466         hot_card_cache->reset_card_counts();
1467         hot_card_cache->reset_hot_cache();
1468       }
1469 
1470       // Rebuild remembered sets of all regions.
1471       if (G1CollectedHeap::use_parallel_gc_threads()) {
1472         uint n_workers =
1473           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1474                                                   workers()->active_workers(),
1475                                                   Threads::number_of_non_daemon_threads());
1476         assert(UseDynamicNumberOfGCThreads ||
1477                n_workers == workers()->total_workers(),
1478                "If not dynamic should be using all the  workers");
1479         workers()->set_active_workers(n_workers);
1480         // Set parallel threads in the heap (_n_par_threads) only
1481         // before a parallel phase and always reset it to 0 after
1482         // the phase so that the number of parallel threads does
1483         // no get carried forward to a serial phase where there
1484         // may be code that is "possibly_parallel".
1485         set_par_threads(n_workers);
1486 
1487         ParRebuildRSTask rebuild_rs_task(this);
1488         assert(check_heap_region_claim_values(
1489                HeapRegion::InitialClaimValue), "sanity check");
1490         assert(UseDynamicNumberOfGCThreads ||
1491                workers()->active_workers() == workers()->total_workers(),
1492                "Unless dynamic should use total workers");
1493         // Use the most recent number of  active workers
1494         assert(workers()->active_workers() > 0,
1495                "Active workers not properly set");
1496         set_par_threads(workers()->active_workers());
1497         workers()->run_task(&rebuild_rs_task);
1498         set_par_threads(0);
1499         assert(check_heap_region_claim_values(
1500                HeapRegion::RebuildRSClaimValue), "sanity check");
1501         reset_heap_region_claim_values();
1502       } else {
1503         RebuildRSOutOfRegionClosure rebuild_rs(this);
1504         heap_region_iterate(&rebuild_rs);
1505       }
1506 
1507       if (true) { // FIXME
1508         MetaspaceGC::compute_new_size();
1509       }
1510 
1511 #ifdef TRACESPINNING
1512       ParallelTaskTerminator::print_termination_counts();
1513 #endif
1514 
1515       // Discard all rset updates
1516       JavaThread::dirty_card_queue_set().abandon_logs();
1517       assert(!G1DeferredRSUpdate
1518              || (G1DeferredRSUpdate &&
1519                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1520 
1521       _young_list->reset_sampled_info();
1522       // At this point there should be no regions in the
1523       // entire heap tagged as young.
1524       assert(check_young_list_empty(true /* check_heap */),
1525              "young list should be empty at this point");
1526 
1527       // Update the number of full collections that have been completed.
1528       increment_old_marking_cycles_completed(false /* concurrent */);
1529 
1530       _hrs.verify_optional();
1531       verify_region_sets_optional();
1532 
1533       verify_after_gc();
1534 
1535       // Start a new incremental collection set for the next pause
1536       assert(g1_policy()->collection_set() == NULL, "must be");
1537       g1_policy()->start_incremental_cset_building();
1538 
1539       // Clear the _cset_fast_test bitmap in anticipation of adding
1540       // regions to the incremental collection set for the next
1541       // evacuation pause.
1542       clear_cset_fast_test();
1543 
1544       init_mutator_alloc_region();
1545 
1546       double end = os::elapsedTime();
1547       g1_policy()->record_full_collection_end();
1548 
1549       if (G1Log::fine()) {
1550         g1_policy()->print_heap_transition();
1551       }
1552 
1553       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1554       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1555       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1556       // before any GC notifications are raised.
1557       g1mm()->update_sizes();
1558 
1559       gc_epilogue(true);
1560     }
1561 
1562     if (G1Log::finer()) {
1563       g1_policy()->print_detailed_heap_transition(true /* full */);
1564     }
1565 
1566     print_heap_after_gc();
1567     trace_heap_after_gc(gc_tracer);
1568 
1569     post_full_gc_dump(gc_timer);
1570 
1571     gc_timer->register_gc_end(os::elapsed_counter());
1572     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1573   }
1574 
1575   return true;
1576 }
1577 
1578 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1579   // do_collection() will return whether it succeeded in performing
1580   // the GC. Currently, there is no facility on the
1581   // do_full_collection() API to notify the caller than the collection
1582   // did not succeed (e.g., because it was locked out by the GC
1583   // locker). So, right now, we'll ignore the return value.
1584   bool dummy = do_collection(true,                /* explicit_gc */
1585                              clear_all_soft_refs,
1586                              0                    /* word_size */);
1587 }
1588 
1589 // This code is mostly copied from TenuredGeneration.
1590 void
1591 G1CollectedHeap::
1592 resize_if_necessary_after_full_collection(size_t word_size) {
1593   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1594 
1595   // Include the current allocation, if any, and bytes that will be
1596   // pre-allocated to support collections, as "used".
1597   const size_t used_after_gc = used();
1598   const size_t capacity_after_gc = capacity();
1599   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1600 
1601   // This is enforced in arguments.cpp.
1602   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1603          "otherwise the code below doesn't make sense");
1604 
1605   // We don't have floating point command-line arguments
1606   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1607   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1608   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1609   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1610 
1611   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1612   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1613 
1614   // We have to be careful here as these two calculations can overflow
1615   // 32-bit size_t's.
1616   double used_after_gc_d = (double) used_after_gc;
1617   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1618   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1619 
1620   // Let's make sure that they are both under the max heap size, which
1621   // by default will make them fit into a size_t.
1622   double desired_capacity_upper_bound = (double) max_heap_size;
1623   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1624                                     desired_capacity_upper_bound);
1625   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1626                                     desired_capacity_upper_bound);
1627 
1628   // We can now safely turn them into size_t's.
1629   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1630   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1631 
1632   // This assert only makes sense here, before we adjust them
1633   // with respect to the min and max heap size.
1634   assert(minimum_desired_capacity <= maximum_desired_capacity,
1635          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1636                  "maximum_desired_capacity = "SIZE_FORMAT,
1637                  minimum_desired_capacity, maximum_desired_capacity));
1638 
1639   // Should not be greater than the heap max size. No need to adjust
1640   // it with respect to the heap min size as it's a lower bound (i.e.,
1641   // we'll try to make the capacity larger than it, not smaller).
1642   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1643   // Should not be less than the heap min size. No need to adjust it
1644   // with respect to the heap max size as it's an upper bound (i.e.,
1645   // we'll try to make the capacity smaller than it, not greater).
1646   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1647 
1648   if (capacity_after_gc < minimum_desired_capacity) {
1649     // Don't expand unless it's significant
1650     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1651     ergo_verbose4(ErgoHeapSizing,
1652                   "attempt heap expansion",
1653                   ergo_format_reason("capacity lower than "
1654                                      "min desired capacity after Full GC")
1655                   ergo_format_byte("capacity")
1656                   ergo_format_byte("occupancy")
1657                   ergo_format_byte_perc("min desired capacity"),
1658                   capacity_after_gc, used_after_gc,
1659                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1660     expand(expand_bytes);
1661 
1662     // No expansion, now see if we want to shrink
1663   } else if (capacity_after_gc > maximum_desired_capacity) {
1664     // Capacity too large, compute shrinking size
1665     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1666     ergo_verbose4(ErgoHeapSizing,
1667                   "attempt heap shrinking",
1668                   ergo_format_reason("capacity higher than "
1669                                      "max desired capacity after Full GC")
1670                   ergo_format_byte("capacity")
1671                   ergo_format_byte("occupancy")
1672                   ergo_format_byte_perc("max desired capacity"),
1673                   capacity_after_gc, used_after_gc,
1674                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1675     shrink(shrink_bytes);
1676   }
1677 }
1678 
1679 
1680 HeapWord*
1681 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1682                                            bool* succeeded) {
1683   assert_at_safepoint(true /* should_be_vm_thread */);
1684 
1685   *succeeded = true;
1686   // Let's attempt the allocation first.
1687   HeapWord* result =
1688     attempt_allocation_at_safepoint(word_size,
1689                                  false /* expect_null_mutator_alloc_region */);
1690   if (result != NULL) {
1691     assert(*succeeded, "sanity");
1692     return result;
1693   }
1694 
1695   // In a G1 heap, we're supposed to keep allocation from failing by
1696   // incremental pauses.  Therefore, at least for now, we'll favor
1697   // expansion over collection.  (This might change in the future if we can
1698   // do something smarter than full collection to satisfy a failed alloc.)
1699   result = expand_and_allocate(word_size);
1700   if (result != NULL) {
1701     assert(*succeeded, "sanity");
1702     return result;
1703   }
1704 
1705   // Expansion didn't work, we'll try to do a Full GC.
1706   bool gc_succeeded = do_collection(false, /* explicit_gc */
1707                                     false, /* clear_all_soft_refs */
1708                                     word_size);
1709   if (!gc_succeeded) {
1710     *succeeded = false;
1711     return NULL;
1712   }
1713 
1714   // Retry the allocation
1715   result = attempt_allocation_at_safepoint(word_size,
1716                                   true /* expect_null_mutator_alloc_region */);
1717   if (result != NULL) {
1718     assert(*succeeded, "sanity");
1719     return result;
1720   }
1721 
1722   // Then, try a Full GC that will collect all soft references.
1723   gc_succeeded = do_collection(false, /* explicit_gc */
1724                                true,  /* clear_all_soft_refs */
1725                                word_size);
1726   if (!gc_succeeded) {
1727     *succeeded = false;
1728     return NULL;
1729   }
1730 
1731   // Retry the allocation once more
1732   result = attempt_allocation_at_safepoint(word_size,
1733                                   true /* expect_null_mutator_alloc_region */);
1734   if (result != NULL) {
1735     assert(*succeeded, "sanity");
1736     return result;
1737   }
1738 
1739   assert(!collector_policy()->should_clear_all_soft_refs(),
1740          "Flag should have been handled and cleared prior to this point");
1741 
1742   // What else?  We might try synchronous finalization later.  If the total
1743   // space available is large enough for the allocation, then a more
1744   // complete compaction phase than we've tried so far might be
1745   // appropriate.
1746   assert(*succeeded, "sanity");
1747   return NULL;
1748 }
1749 
1750 // Attempting to expand the heap sufficiently
1751 // to support an allocation of the given "word_size".  If
1752 // successful, perform the allocation and return the address of the
1753 // allocated block, or else "NULL".
1754 
1755 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1756   assert_at_safepoint(true /* should_be_vm_thread */);
1757 
1758   verify_region_sets_optional();
1759 
1760   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1761   ergo_verbose1(ErgoHeapSizing,
1762                 "attempt heap expansion",
1763                 ergo_format_reason("allocation request failed")
1764                 ergo_format_byte("allocation request"),
1765                 word_size * HeapWordSize);
1766   if (expand(expand_bytes)) {
1767     _hrs.verify_optional();
1768     verify_region_sets_optional();
1769     return attempt_allocation_at_safepoint(word_size,
1770                                  false /* expect_null_mutator_alloc_region */);
1771   }
1772   return NULL;
1773 }
1774 
1775 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1776                                              HeapWord* new_end) {
1777   assert(old_end != new_end, "don't call this otherwise");
1778   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1779 
1780   // Update the committed mem region.
1781   _g1_committed.set_end(new_end);
1782   // Tell the card table about the update.
1783   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1784   // Tell the BOT about the update.
1785   _bot_shared->resize(_g1_committed.word_size());
1786   // Tell the hot card cache about the update
1787   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1788 }
1789 
1790 bool G1CollectedHeap::expand(size_t expand_bytes) {
1791   size_t old_mem_size = _g1_storage.committed_size();
1792   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1793   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1794                                        HeapRegion::GrainBytes);
1795   ergo_verbose2(ErgoHeapSizing,
1796                 "expand the heap",
1797                 ergo_format_byte("requested expansion amount")
1798                 ergo_format_byte("attempted expansion amount"),
1799                 expand_bytes, aligned_expand_bytes);
1800 
1801   // First commit the memory.
1802   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1803   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1804   if (successful) {
1805     // Then propagate this update to the necessary data structures.
1806     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1807     update_committed_space(old_end, new_end);
1808 
1809     FreeRegionList expansion_list("Local Expansion List");
1810     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1811     assert(mr.start() == old_end, "post-condition");
1812     // mr might be a smaller region than what was requested if
1813     // expand_by() was unable to allocate the HeapRegion instances
1814     assert(mr.end() <= new_end, "post-condition");
1815 
1816     size_t actual_expand_bytes = mr.byte_size();
1817     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1818     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1819            "post-condition");
1820     if (actual_expand_bytes < aligned_expand_bytes) {
1821       // We could not expand _hrs to the desired size. In this case we
1822       // need to shrink the committed space accordingly.
1823       assert(mr.end() < new_end, "invariant");
1824 
1825       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1826       // First uncommit the memory.
1827       _g1_storage.shrink_by(diff_bytes);
1828       // Then propagate this update to the necessary data structures.
1829       update_committed_space(new_end, mr.end());
1830     }
1831     _free_list.add_as_tail(&expansion_list);
1832 
1833     if (_hr_printer.is_active()) {
1834       HeapWord* curr = mr.start();
1835       while (curr < mr.end()) {
1836         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1837         _hr_printer.commit(curr, curr_end);
1838         curr = curr_end;
1839       }
1840       assert(curr == mr.end(), "post-condition");
1841     }
1842     g1_policy()->record_new_heap_size(n_regions());
1843   } else {
1844     ergo_verbose0(ErgoHeapSizing,
1845                   "did not expand the heap",
1846                   ergo_format_reason("heap expansion operation failed"));
1847     // The expansion of the virtual storage space was unsuccessful.
1848     // Let's see if it was because we ran out of swap.
1849     if (G1ExitOnExpansionFailure &&
1850         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1851       // We had head room...
1852       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1853     }
1854   }
1855   return successful;
1856 }
1857 
1858 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1859   size_t old_mem_size = _g1_storage.committed_size();
1860   size_t aligned_shrink_bytes =
1861     ReservedSpace::page_align_size_down(shrink_bytes);
1862   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1863                                          HeapRegion::GrainBytes);
1864   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1865 
1866   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1867   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1868   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1869 
1870   ergo_verbose3(ErgoHeapSizing,
1871                 "shrink the heap",
1872                 ergo_format_byte("requested shrinking amount")
1873                 ergo_format_byte("aligned shrinking amount")
1874                 ergo_format_byte("attempted shrinking amount"),
1875                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1876   if (num_regions_removed > 0) {
1877     _g1_storage.shrink_by(shrunk_bytes);
1878     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1879 
1880     if (_hr_printer.is_active()) {
1881       HeapWord* curr = old_end;
1882       while (curr > new_end) {
1883         HeapWord* curr_end = curr;
1884         curr -= HeapRegion::GrainWords;
1885         _hr_printer.uncommit(curr, curr_end);
1886       }
1887     }
1888 
1889     _expansion_regions += num_regions_removed;
1890     update_committed_space(old_end, new_end);
1891     HeapRegionRemSet::shrink_heap(n_regions());
1892     g1_policy()->record_new_heap_size(n_regions());
1893   } else {
1894     ergo_verbose0(ErgoHeapSizing,
1895                   "did not shrink the heap",
1896                   ergo_format_reason("heap shrinking operation failed"));
1897   }
1898 }
1899 
1900 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1901   verify_region_sets_optional();
1902 
1903   // We should only reach here at the end of a Full GC which means we
1904   // should not not be holding to any GC alloc regions. The method
1905   // below will make sure of that and do any remaining clean up.
1906   abandon_gc_alloc_regions();
1907 
1908   // Instead of tearing down / rebuilding the free lists here, we
1909   // could instead use the remove_all_pending() method on free_list to
1910   // remove only the ones that we need to remove.
1911   tear_down_region_sets(true /* free_list_only */);
1912   shrink_helper(shrink_bytes);
1913   rebuild_region_sets(true /* free_list_only */);
1914 
1915   _hrs.verify_optional();
1916   verify_region_sets_optional();
1917 }
1918 
1919 // Public methods.
1920 
1921 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1922 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1923 #endif // _MSC_VER
1924 
1925 
1926 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1927   SharedHeap(policy_),
1928   _g1_policy(policy_),
1929   _dirty_card_queue_set(false),
1930   _into_cset_dirty_card_queue_set(false),
1931   _is_alive_closure_cm(this),
1932   _is_alive_closure_stw(this),
1933   _ref_processor_cm(NULL),
1934   _ref_processor_stw(NULL),
1935   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1936   _bot_shared(NULL),
1937   _evac_failure_scan_stack(NULL),
1938   _mark_in_progress(false),
1939   _cg1r(NULL), _summary_bytes_used(0),
1940   _g1mm(NULL),
1941   _refine_cte_cl(NULL),
1942   _full_collection(false),
1943   _free_list("Master Free List"),
1944   _secondary_free_list("Secondary Free List"),
1945   _old_set("Old Set"),
1946   _humongous_set("Master Humongous Set"),
1947   _free_regions_coming(false),
1948   _young_list(new YoungList(this)),
1949   _gc_time_stamp(0),
1950   _retained_old_gc_alloc_region(NULL),
1951   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1952   _old_plab_stats(OldPLABSize, PLABWeight),
1953   _expand_heap_after_alloc_failure(true),
1954   _surviving_young_words(NULL),
1955   _old_marking_cycles_started(0),
1956   _old_marking_cycles_completed(0),
1957   _concurrent_cycle_started(false),
1958   _in_cset_fast_test(NULL),
1959   _in_cset_fast_test_base(NULL),
1960   _dirty_cards_region_list(NULL),
1961   _worker_cset_start_region(NULL),
1962   _worker_cset_start_region_time_stamp(NULL),
1963   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1964   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1965   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1966   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1967 
1968   _g1h = this;
1969   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1970     vm_exit_during_initialization("Failed necessary allocation.");
1971   }
1972 
1973   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1974 
1975   int n_queues = MAX2((int)ParallelGCThreads, 1);
1976   _task_queues = new RefToScanQueueSet(n_queues);
1977 
1978   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1979   assert(n_rem_sets > 0, "Invariant.");
1980 
1981   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1982   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1983   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1984 
1985   for (int i = 0; i < n_queues; i++) {
1986     RefToScanQueue* q = new RefToScanQueue();
1987     q->initialize();
1988     _task_queues->register_queue(i, q);
1989     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1990   }
1991   clear_cset_start_regions();
1992 
1993   // Initialize the G1EvacuationFailureALot counters and flags.
1994   NOT_PRODUCT(reset_evacuation_should_fail();)
1995 
1996   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1997 }
1998 
1999 jint G1CollectedHeap::initialize() {
2000   CollectedHeap::pre_initialize();
2001   os::enable_vtime();
2002 
2003   G1Log::init();
2004 
2005   // Necessary to satisfy locking discipline assertions.
2006 
2007   MutexLocker x(Heap_lock);
2008 
2009   // We have to initialize the printer before committing the heap, as
2010   // it will be used then.
2011   _hr_printer.set_active(G1PrintHeapRegions);
2012 
2013   // While there are no constraints in the GC code that HeapWordSize
2014   // be any particular value, there are multiple other areas in the
2015   // system which believe this to be true (e.g. oop->object_size in some
2016   // cases incorrectly returns the size in wordSize units rather than
2017   // HeapWordSize).
2018   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2019 
2020   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2021   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2022   size_t heap_alignment = collector_policy()->max_alignment();
2023 
2024   // Ensure that the sizes are properly aligned.
2025   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2026   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2027   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2028 
2029   _cg1r = new ConcurrentG1Refine(this);
2030 
2031   // Reserve the maximum.
2032 
2033   // When compressed oops are enabled, the preferred heap base
2034   // is calculated by subtracting the requested size from the
2035   // 32Gb boundary and using the result as the base address for
2036   // heap reservation. If the requested size is not aligned to
2037   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2038   // into the ReservedHeapSpace constructor) then the actual
2039   // base of the reserved heap may end up differing from the
2040   // address that was requested (i.e. the preferred heap base).
2041   // If this happens then we could end up using a non-optimal
2042   // compressed oops mode.
2043 




2044   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2045                                                  heap_alignment);
2046 
2047   // It is important to do this in a way such that concurrent readers can't
2048   // temporarily think something is in the heap.  (I've actually seen this
2049   // happen in asserts: DLD.)
2050   _reserved.set_word_size(0);
2051   _reserved.set_start((HeapWord*)heap_rs.base());
2052   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2053 
2054   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2055 
2056   // Create the gen rem set (and barrier set) for the entire reserved region.
2057   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2058   set_barrier_set(rem_set()->bs());
2059   if (barrier_set()->is_a(BarrierSet::ModRef)) {
2060     _mr_bs = (ModRefBarrierSet*)_barrier_set;
2061   } else {
2062     vm_exit_during_initialization("G1 requires a mod ref bs.");
2063     return JNI_ENOMEM;
2064   }
2065 
2066   // Also create a G1 rem set.
2067   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2068     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2069   } else {
2070     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2071     return JNI_ENOMEM;
2072   }
2073 
2074   // Carve out the G1 part of the heap.
2075 
2076   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2077   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2078                            g1_rs.size()/HeapWordSize);
2079 
2080   _g1_storage.initialize(g1_rs, 0);
2081   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2082   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2083                   (HeapWord*) _g1_reserved.end(),
2084                   _expansion_regions);
2085 
2086   // Do later initialization work for concurrent refinement.
2087   _cg1r->init();
2088 
2089   // 6843694 - ensure that the maximum region index can fit
2090   // in the remembered set structures.
2091   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2092   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2093 
2094   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2095   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2096   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2097             "too many cards per region");
2098 
2099   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2100 
2101   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2102                                              heap_word_size(init_byte_size));
2103 
2104   _g1h = this;
2105 
2106   _in_cset_fast_test_length = max_regions();
2107   _in_cset_fast_test_base =
2108                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2109 
2110   // We're biasing _in_cset_fast_test to avoid subtracting the
2111   // beginning of the heap every time we want to index; basically
2112   // it's the same with what we do with the card table.
2113   _in_cset_fast_test = _in_cset_fast_test_base -
2114                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2115 
2116   // Clear the _cset_fast_test bitmap in anticipation of adding
2117   // regions to the incremental collection set for the first
2118   // evacuation pause.
2119   clear_cset_fast_test();
2120 
2121   // Create the ConcurrentMark data structure and thread.
2122   // (Must do this late, so that "max_regions" is defined.)
2123   _cm = new ConcurrentMark(this, heap_rs);
2124   if (_cm == NULL || !_cm->completed_initialization()) {
2125     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2126     return JNI_ENOMEM;
2127   }
2128   _cmThread = _cm->cmThread();
2129 
2130   // Initialize the from_card cache structure of HeapRegionRemSet.
2131   HeapRegionRemSet::init_heap(max_regions());
2132 
2133   // Now expand into the initial heap size.
2134   if (!expand(init_byte_size)) {
2135     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2136     return JNI_ENOMEM;
2137   }
2138 
2139   // Perform any initialization actions delegated to the policy.
2140   g1_policy()->init();
2141 
2142   _refine_cte_cl =
2143     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2144                                     g1_rem_set(),
2145                                     concurrent_g1_refine());
2146   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2147 
2148   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2149                                                SATB_Q_FL_lock,
2150                                                G1SATBProcessCompletedThreshold,
2151                                                Shared_SATB_Q_lock);
2152 
2153   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2154                                                 DirtyCardQ_FL_lock,
2155                                                 concurrent_g1_refine()->yellow_zone(),
2156                                                 concurrent_g1_refine()->red_zone(),
2157                                                 Shared_DirtyCardQ_lock);
2158 
2159   if (G1DeferredRSUpdate) {
2160     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2161                                       DirtyCardQ_FL_lock,
2162                                       -1, // never trigger processing
2163                                       -1, // no limit on length
2164                                       Shared_DirtyCardQ_lock,
2165                                       &JavaThread::dirty_card_queue_set());
2166   }
2167 
2168   // Initialize the card queue set used to hold cards containing
2169   // references into the collection set.
2170   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2171                                              DirtyCardQ_FL_lock,
2172                                              -1, // never trigger processing
2173                                              -1, // no limit on length
2174                                              Shared_DirtyCardQ_lock,
2175                                              &JavaThread::dirty_card_queue_set());
2176 
2177   // In case we're keeping closure specialization stats, initialize those
2178   // counts and that mechanism.
2179   SpecializationStats::clear();
2180 
2181   // Here we allocate the dummy full region that is required by the
2182   // G1AllocRegion class. If we don't pass an address in the reserved
2183   // space here, lots of asserts fire.
2184 
2185   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2186                                              _g1_reserved.start());
2187   // We'll re-use the same region whether the alloc region will
2188   // require BOT updates or not and, if it doesn't, then a non-young
2189   // region will complain that it cannot support allocations without
2190   // BOT updates. So we'll tag the dummy region as young to avoid that.
2191   dummy_region->set_young();
2192   // Make sure it's full.
2193   dummy_region->set_top(dummy_region->end());
2194   G1AllocRegion::setup(this, dummy_region);
2195 
2196   init_mutator_alloc_region();
2197 
2198   // Do create of the monitoring and management support so that
2199   // values in the heap have been properly initialized.
2200   _g1mm = new G1MonitoringSupport(this);
2201 
2202   return JNI_OK;
2203 }
2204 
2205 void G1CollectedHeap::ref_processing_init() {
2206   // Reference processing in G1 currently works as follows:
2207   //
2208   // * There are two reference processor instances. One is
2209   //   used to record and process discovered references
2210   //   during concurrent marking; the other is used to
2211   //   record and process references during STW pauses
2212   //   (both full and incremental).
2213   // * Both ref processors need to 'span' the entire heap as
2214   //   the regions in the collection set may be dotted around.
2215   //
2216   // * For the concurrent marking ref processor:
2217   //   * Reference discovery is enabled at initial marking.
2218   //   * Reference discovery is disabled and the discovered
2219   //     references processed etc during remarking.
2220   //   * Reference discovery is MT (see below).
2221   //   * Reference discovery requires a barrier (see below).
2222   //   * Reference processing may or may not be MT
2223   //     (depending on the value of ParallelRefProcEnabled
2224   //     and ParallelGCThreads).
2225   //   * A full GC disables reference discovery by the CM
2226   //     ref processor and abandons any entries on it's
2227   //     discovered lists.
2228   //
2229   // * For the STW processor:
2230   //   * Non MT discovery is enabled at the start of a full GC.
2231   //   * Processing and enqueueing during a full GC is non-MT.
2232   //   * During a full GC, references are processed after marking.
2233   //
2234   //   * Discovery (may or may not be MT) is enabled at the start
2235   //     of an incremental evacuation pause.
2236   //   * References are processed near the end of a STW evacuation pause.
2237   //   * For both types of GC:
2238   //     * Discovery is atomic - i.e. not concurrent.
2239   //     * Reference discovery will not need a barrier.
2240 
2241   SharedHeap::ref_processing_init();
2242   MemRegion mr = reserved_region();
2243 
2244   // Concurrent Mark ref processor
2245   _ref_processor_cm =
2246     new ReferenceProcessor(mr,    // span
2247                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2248                                 // mt processing
2249                            (int) ParallelGCThreads,
2250                                 // degree of mt processing
2251                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2252                                 // mt discovery
2253                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2254                                 // degree of mt discovery
2255                            false,
2256                                 // Reference discovery is not atomic
2257                            &_is_alive_closure_cm,
2258                                 // is alive closure
2259                                 // (for efficiency/performance)
2260                            true);
2261                                 // Setting next fields of discovered
2262                                 // lists requires a barrier.
2263 
2264   // STW ref processor
2265   _ref_processor_stw =
2266     new ReferenceProcessor(mr,    // span
2267                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2268                                 // mt processing
2269                            MAX2((int)ParallelGCThreads, 1),
2270                                 // degree of mt processing
2271                            (ParallelGCThreads > 1),
2272                                 // mt discovery
2273                            MAX2((int)ParallelGCThreads, 1),
2274                                 // degree of mt discovery
2275                            true,
2276                                 // Reference discovery is atomic
2277                            &_is_alive_closure_stw,
2278                                 // is alive closure
2279                                 // (for efficiency/performance)
2280                            false);
2281                                 // Setting next fields of discovered
2282                                 // lists requires a barrier.
2283 }
2284 
2285 size_t G1CollectedHeap::capacity() const {
2286   return _g1_committed.byte_size();
2287 }
2288 
2289 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2290   assert(!hr->continuesHumongous(), "pre-condition");
2291   hr->reset_gc_time_stamp();
2292   if (hr->startsHumongous()) {
2293     uint first_index = hr->hrs_index() + 1;
2294     uint last_index = hr->last_hc_index();
2295     for (uint i = first_index; i < last_index; i += 1) {
2296       HeapRegion* chr = region_at(i);
2297       assert(chr->continuesHumongous(), "sanity");
2298       chr->reset_gc_time_stamp();
2299     }
2300   }
2301 }
2302 
2303 #ifndef PRODUCT
2304 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2305 private:
2306   unsigned _gc_time_stamp;
2307   bool _failures;
2308 
2309 public:
2310   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2311     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2312 
2313   virtual bool doHeapRegion(HeapRegion* hr) {
2314     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2315     if (_gc_time_stamp != region_gc_time_stamp) {
2316       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2317                              "expected %d", HR_FORMAT_PARAMS(hr),
2318                              region_gc_time_stamp, _gc_time_stamp);
2319       _failures = true;
2320     }
2321     return false;
2322   }
2323 
2324   bool failures() { return _failures; }
2325 };
2326 
2327 void G1CollectedHeap::check_gc_time_stamps() {
2328   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2329   heap_region_iterate(&cl);
2330   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2331 }
2332 #endif // PRODUCT
2333 
2334 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2335                                                  DirtyCardQueue* into_cset_dcq,
2336                                                  bool concurrent,
2337                                                  int worker_i) {
2338   // Clean cards in the hot card cache
2339   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2340   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2341 
2342   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2343   int n_completed_buffers = 0;
2344   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2345     n_completed_buffers++;
2346   }
2347   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2348   dcqs.clear_n_completed_buffers();
2349   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2350 }
2351 
2352 
2353 // Computes the sum of the storage used by the various regions.
2354 
2355 size_t G1CollectedHeap::used() const {
2356   assert(Heap_lock->owner() != NULL,
2357          "Should be owned on this thread's behalf.");
2358   size_t result = _summary_bytes_used;
2359   // Read only once in case it is set to NULL concurrently
2360   HeapRegion* hr = _mutator_alloc_region.get();
2361   if (hr != NULL)
2362     result += hr->used();
2363   return result;
2364 }
2365 
2366 size_t G1CollectedHeap::used_unlocked() const {
2367   size_t result = _summary_bytes_used;
2368   return result;
2369 }
2370 
2371 class SumUsedClosure: public HeapRegionClosure {
2372   size_t _used;
2373 public:
2374   SumUsedClosure() : _used(0) {}
2375   bool doHeapRegion(HeapRegion* r) {
2376     if (!r->continuesHumongous()) {
2377       _used += r->used();
2378     }
2379     return false;
2380   }
2381   size_t result() { return _used; }
2382 };
2383 
2384 size_t G1CollectedHeap::recalculate_used() const {
2385   SumUsedClosure blk;
2386   heap_region_iterate(&blk);
2387   return blk.result();
2388 }
2389 
2390 size_t G1CollectedHeap::unsafe_max_alloc() {
2391   if (free_regions() > 0) return HeapRegion::GrainBytes;
2392   // otherwise, is there space in the current allocation region?
2393 
2394   // We need to store the current allocation region in a local variable
2395   // here. The problem is that this method doesn't take any locks and
2396   // there may be other threads which overwrite the current allocation
2397   // region field. attempt_allocation(), for example, sets it to NULL
2398   // and this can happen *after* the NULL check here but before the call
2399   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2400   // to be a problem in the optimized build, since the two loads of the
2401   // current allocation region field are optimized away.
2402   HeapRegion* hr = _mutator_alloc_region.get();
2403   if (hr == NULL) {
2404     return 0;
2405   }
2406   return hr->free();
2407 }
2408 
2409 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2410   switch (cause) {
2411     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2412     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2413     case GCCause::_g1_humongous_allocation: return true;
2414     default:                                return false;
2415   }
2416 }
2417 
2418 #ifndef PRODUCT
2419 void G1CollectedHeap::allocate_dummy_regions() {
2420   // Let's fill up most of the region
2421   size_t word_size = HeapRegion::GrainWords - 1024;
2422   // And as a result the region we'll allocate will be humongous.
2423   guarantee(isHumongous(word_size), "sanity");
2424 
2425   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2426     // Let's use the existing mechanism for the allocation
2427     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2428     if (dummy_obj != NULL) {
2429       MemRegion mr(dummy_obj, word_size);
2430       CollectedHeap::fill_with_object(mr);
2431     } else {
2432       // If we can't allocate once, we probably cannot allocate
2433       // again. Let's get out of the loop.
2434       break;
2435     }
2436   }
2437 }
2438 #endif // !PRODUCT
2439 
2440 void G1CollectedHeap::increment_old_marking_cycles_started() {
2441   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2442     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2443     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2444     _old_marking_cycles_started, _old_marking_cycles_completed));
2445 
2446   _old_marking_cycles_started++;
2447 }
2448 
2449 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2450   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2451 
2452   // We assume that if concurrent == true, then the caller is a
2453   // concurrent thread that was joined the Suspendible Thread
2454   // Set. If there's ever a cheap way to check this, we should add an
2455   // assert here.
2456 
2457   // Given that this method is called at the end of a Full GC or of a
2458   // concurrent cycle, and those can be nested (i.e., a Full GC can
2459   // interrupt a concurrent cycle), the number of full collections
2460   // completed should be either one (in the case where there was no
2461   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2462   // behind the number of full collections started.
2463 
2464   // This is the case for the inner caller, i.e. a Full GC.
2465   assert(concurrent ||
2466          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2467          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2468          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2469                  "is inconsistent with _old_marking_cycles_completed = %u",
2470                  _old_marking_cycles_started, _old_marking_cycles_completed));
2471 
2472   // This is the case for the outer caller, i.e. the concurrent cycle.
2473   assert(!concurrent ||
2474          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2475          err_msg("for outer caller (concurrent cycle): "
2476                  "_old_marking_cycles_started = %u "
2477                  "is inconsistent with _old_marking_cycles_completed = %u",
2478                  _old_marking_cycles_started, _old_marking_cycles_completed));
2479 
2480   _old_marking_cycles_completed += 1;
2481 
2482   // We need to clear the "in_progress" flag in the CM thread before
2483   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2484   // is set) so that if a waiter requests another System.gc() it doesn't
2485   // incorrectly see that a marking cycle is still in progress.
2486   if (concurrent) {
2487     _cmThread->clear_in_progress();
2488   }
2489 
2490   // This notify_all() will ensure that a thread that called
2491   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2492   // and it's waiting for a full GC to finish will be woken up. It is
2493   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2494   FullGCCount_lock->notify_all();
2495 }
2496 
2497 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2498   _concurrent_cycle_started = true;
2499   _gc_timer_cm->register_gc_start(start_time);
2500 
2501   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2502   trace_heap_before_gc(_gc_tracer_cm);
2503 }
2504 
2505 void G1CollectedHeap::register_concurrent_cycle_end() {
2506   if (_concurrent_cycle_started) {
2507     _gc_timer_cm->register_gc_end(os::elapsed_counter());
2508 
2509     if (_cm->has_aborted()) {
2510       _gc_tracer_cm->report_concurrent_mode_failure();
2511     }
2512     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2513 
2514     _concurrent_cycle_started = false;
2515   }
2516 }
2517 
2518 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2519   if (_concurrent_cycle_started) {
2520     trace_heap_after_gc(_gc_tracer_cm);
2521   }
2522 }
2523 
2524 G1YCType G1CollectedHeap::yc_type() {
2525   bool is_young = g1_policy()->gcs_are_young();
2526   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2527   bool is_during_mark = mark_in_progress();
2528 
2529   if (is_initial_mark) {
2530     return InitialMark;
2531   } else if (is_during_mark) {
2532     return DuringMark;
2533   } else if (is_young) {
2534     return Normal;
2535   } else {
2536     return Mixed;
2537   }
2538 }
2539 
2540 void G1CollectedHeap::collect(GCCause::Cause cause) {
2541   assert_heap_not_locked();
2542 
2543   unsigned int gc_count_before;
2544   unsigned int old_marking_count_before;
2545   bool retry_gc;
2546 
2547   do {
2548     retry_gc = false;
2549 
2550     {
2551       MutexLocker ml(Heap_lock);
2552 
2553       // Read the GC count while holding the Heap_lock
2554       gc_count_before = total_collections();
2555       old_marking_count_before = _old_marking_cycles_started;
2556     }
2557 
2558     if (should_do_concurrent_full_gc(cause)) {
2559       // Schedule an initial-mark evacuation pause that will start a
2560       // concurrent cycle. We're setting word_size to 0 which means that
2561       // we are not requesting a post-GC allocation.
2562       VM_G1IncCollectionPause op(gc_count_before,
2563                                  0,     /* word_size */
2564                                  true,  /* should_initiate_conc_mark */
2565                                  g1_policy()->max_pause_time_ms(),
2566                                  cause);
2567 
2568       VMThread::execute(&op);
2569       if (!op.pause_succeeded()) {
2570         if (old_marking_count_before == _old_marking_cycles_started) {
2571           retry_gc = op.should_retry_gc();
2572         } else {
2573           // A Full GC happened while we were trying to schedule the
2574           // initial-mark GC. No point in starting a new cycle given
2575           // that the whole heap was collected anyway.
2576         }
2577 
2578         if (retry_gc) {
2579           if (GC_locker::is_active_and_needs_gc()) {
2580             GC_locker::stall_until_clear();
2581           }
2582         }
2583       }
2584     } else {
2585       if (cause == GCCause::_gc_locker
2586           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2587 
2588         // Schedule a standard evacuation pause. We're setting word_size
2589         // to 0 which means that we are not requesting a post-GC allocation.
2590         VM_G1IncCollectionPause op(gc_count_before,
2591                                    0,     /* word_size */
2592                                    false, /* should_initiate_conc_mark */
2593                                    g1_policy()->max_pause_time_ms(),
2594                                    cause);
2595         VMThread::execute(&op);
2596       } else {
2597         // Schedule a Full GC.
2598         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2599         VMThread::execute(&op);
2600       }
2601     }
2602   } while (retry_gc);
2603 }
2604 
2605 bool G1CollectedHeap::is_in(const void* p) const {
2606   if (_g1_committed.contains(p)) {
2607     // Given that we know that p is in the committed space,
2608     // heap_region_containing_raw() should successfully
2609     // return the containing region.
2610     HeapRegion* hr = heap_region_containing_raw(p);
2611     return hr->is_in(p);
2612   } else {
2613     return false;
2614   }
2615 }
2616 
2617 // Iteration functions.
2618 
2619 // Iterates an OopClosure over all ref-containing fields of objects
2620 // within a HeapRegion.
2621 
2622 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2623   MemRegion _mr;
2624   ExtendedOopClosure* _cl;
2625 public:
2626   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2627     : _mr(mr), _cl(cl) {}
2628   bool doHeapRegion(HeapRegion* r) {
2629     if (!r->continuesHumongous()) {
2630       r->oop_iterate(_cl);
2631     }
2632     return false;
2633   }
2634 };
2635 
2636 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2637   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2638   heap_region_iterate(&blk);
2639 }
2640 
2641 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2642   IterateOopClosureRegionClosure blk(mr, cl);
2643   heap_region_iterate(&blk);
2644 }
2645 
2646 // Iterates an ObjectClosure over all objects within a HeapRegion.
2647 
2648 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2649   ObjectClosure* _cl;
2650 public:
2651   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2652   bool doHeapRegion(HeapRegion* r) {
2653     if (! r->continuesHumongous()) {
2654       r->object_iterate(_cl);
2655     }
2656     return false;
2657   }
2658 };
2659 
2660 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2661   IterateObjectClosureRegionClosure blk(cl);
2662   heap_region_iterate(&blk);
2663 }
2664 
2665 // Calls a SpaceClosure on a HeapRegion.
2666 
2667 class SpaceClosureRegionClosure: public HeapRegionClosure {
2668   SpaceClosure* _cl;
2669 public:
2670   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2671   bool doHeapRegion(HeapRegion* r) {
2672     _cl->do_space(r);
2673     return false;
2674   }
2675 };
2676 
2677 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2678   SpaceClosureRegionClosure blk(cl);
2679   heap_region_iterate(&blk);
2680 }
2681 
2682 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2683   _hrs.iterate(cl);
2684 }
2685 
2686 void
2687 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2688                                                  uint worker_id,
2689                                                  uint no_of_par_workers,
2690                                                  jint claim_value) {
2691   const uint regions = n_regions();
2692   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2693                              no_of_par_workers :
2694                              1);
2695   assert(UseDynamicNumberOfGCThreads ||
2696          no_of_par_workers == workers()->total_workers(),
2697          "Non dynamic should use fixed number of workers");
2698   // try to spread out the starting points of the workers
2699   const HeapRegion* start_hr =
2700                         start_region_for_worker(worker_id, no_of_par_workers);
2701   const uint start_index = start_hr->hrs_index();
2702 
2703   // each worker will actually look at all regions
2704   for (uint count = 0; count < regions; ++count) {
2705     const uint index = (start_index + count) % regions;
2706     assert(0 <= index && index < regions, "sanity");
2707     HeapRegion* r = region_at(index);
2708     // we'll ignore "continues humongous" regions (we'll process them
2709     // when we come across their corresponding "start humongous"
2710     // region) and regions already claimed
2711     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2712       continue;
2713     }
2714     // OK, try to claim it
2715     if (r->claimHeapRegion(claim_value)) {
2716       // success!
2717       assert(!r->continuesHumongous(), "sanity");
2718       if (r->startsHumongous()) {
2719         // If the region is "starts humongous" we'll iterate over its
2720         // "continues humongous" first; in fact we'll do them
2721         // first. The order is important. In on case, calling the
2722         // closure on the "starts humongous" region might de-allocate
2723         // and clear all its "continues humongous" regions and, as a
2724         // result, we might end up processing them twice. So, we'll do
2725         // them first (notice: most closures will ignore them anyway) and
2726         // then we'll do the "starts humongous" region.
2727         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2728           HeapRegion* chr = region_at(ch_index);
2729 
2730           // if the region has already been claimed or it's not
2731           // "continues humongous" we're done
2732           if (chr->claim_value() == claim_value ||
2733               !chr->continuesHumongous()) {
2734             break;
2735           }
2736 
2737           // No one should have claimed it directly. We can given
2738           // that we claimed its "starts humongous" region.
2739           assert(chr->claim_value() != claim_value, "sanity");
2740           assert(chr->humongous_start_region() == r, "sanity");
2741 
2742           if (chr->claimHeapRegion(claim_value)) {
2743             // we should always be able to claim it; no one else should
2744             // be trying to claim this region
2745 
2746             bool res2 = cl->doHeapRegion(chr);
2747             assert(!res2, "Should not abort");
2748 
2749             // Right now, this holds (i.e., no closure that actually
2750             // does something with "continues humongous" regions
2751             // clears them). We might have to weaken it in the future,
2752             // but let's leave these two asserts here for extra safety.
2753             assert(chr->continuesHumongous(), "should still be the case");
2754             assert(chr->humongous_start_region() == r, "sanity");
2755           } else {
2756             guarantee(false, "we should not reach here");
2757           }
2758         }
2759       }
2760 
2761       assert(!r->continuesHumongous(), "sanity");
2762       bool res = cl->doHeapRegion(r);
2763       assert(!res, "Should not abort");
2764     }
2765   }
2766 }
2767 
2768 class ResetClaimValuesClosure: public HeapRegionClosure {
2769 public:
2770   bool doHeapRegion(HeapRegion* r) {
2771     r->set_claim_value(HeapRegion::InitialClaimValue);
2772     return false;
2773   }
2774 };
2775 
2776 void G1CollectedHeap::reset_heap_region_claim_values() {
2777   ResetClaimValuesClosure blk;
2778   heap_region_iterate(&blk);
2779 }
2780 
2781 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2782   ResetClaimValuesClosure blk;
2783   collection_set_iterate(&blk);
2784 }
2785 
2786 #ifdef ASSERT
2787 // This checks whether all regions in the heap have the correct claim
2788 // value. I also piggy-backed on this a check to ensure that the
2789 // humongous_start_region() information on "continues humongous"
2790 // regions is correct.
2791 
2792 class CheckClaimValuesClosure : public HeapRegionClosure {
2793 private:
2794   jint _claim_value;
2795   uint _failures;
2796   HeapRegion* _sh_region;
2797 
2798 public:
2799   CheckClaimValuesClosure(jint claim_value) :
2800     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2801   bool doHeapRegion(HeapRegion* r) {
2802     if (r->claim_value() != _claim_value) {
2803       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2804                              "claim value = %d, should be %d",
2805                              HR_FORMAT_PARAMS(r),
2806                              r->claim_value(), _claim_value);
2807       ++_failures;
2808     }
2809     if (!r->isHumongous()) {
2810       _sh_region = NULL;
2811     } else if (r->startsHumongous()) {
2812       _sh_region = r;
2813     } else if (r->continuesHumongous()) {
2814       if (r->humongous_start_region() != _sh_region) {
2815         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2816                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2817                                HR_FORMAT_PARAMS(r),
2818                                r->humongous_start_region(),
2819                                _sh_region);
2820         ++_failures;
2821       }
2822     }
2823     return false;
2824   }
2825   uint failures() { return _failures; }
2826 };
2827 
2828 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2829   CheckClaimValuesClosure cl(claim_value);
2830   heap_region_iterate(&cl);
2831   return cl.failures() == 0;
2832 }
2833 
2834 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2835 private:
2836   jint _claim_value;
2837   uint _failures;
2838 
2839 public:
2840   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2841     _claim_value(claim_value), _failures(0) { }
2842 
2843   uint failures() { return _failures; }
2844 
2845   bool doHeapRegion(HeapRegion* hr) {
2846     assert(hr->in_collection_set(), "how?");
2847     assert(!hr->isHumongous(), "H-region in CSet");
2848     if (hr->claim_value() != _claim_value) {
2849       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2850                              "claim value = %d, should be %d",
2851                              HR_FORMAT_PARAMS(hr),
2852                              hr->claim_value(), _claim_value);
2853       _failures += 1;
2854     }
2855     return false;
2856   }
2857 };
2858 
2859 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2860   CheckClaimValuesInCSetHRClosure cl(claim_value);
2861   collection_set_iterate(&cl);
2862   return cl.failures() == 0;
2863 }
2864 #endif // ASSERT
2865 
2866 // Clear the cached CSet starting regions and (more importantly)
2867 // the time stamps. Called when we reset the GC time stamp.
2868 void G1CollectedHeap::clear_cset_start_regions() {
2869   assert(_worker_cset_start_region != NULL, "sanity");
2870   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2871 
2872   int n_queues = MAX2((int)ParallelGCThreads, 1);
2873   for (int i = 0; i < n_queues; i++) {
2874     _worker_cset_start_region[i] = NULL;
2875     _worker_cset_start_region_time_stamp[i] = 0;
2876   }
2877 }
2878 
2879 // Given the id of a worker, obtain or calculate a suitable
2880 // starting region for iterating over the current collection set.
2881 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2882   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2883 
2884   HeapRegion* result = NULL;
2885   unsigned gc_time_stamp = get_gc_time_stamp();
2886 
2887   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2888     // Cached starting region for current worker was set
2889     // during the current pause - so it's valid.
2890     // Note: the cached starting heap region may be NULL
2891     // (when the collection set is empty).
2892     result = _worker_cset_start_region[worker_i];
2893     assert(result == NULL || result->in_collection_set(), "sanity");
2894     return result;
2895   }
2896 
2897   // The cached entry was not valid so let's calculate
2898   // a suitable starting heap region for this worker.
2899 
2900   // We want the parallel threads to start their collection
2901   // set iteration at different collection set regions to
2902   // avoid contention.
2903   // If we have:
2904   //          n collection set regions
2905   //          p threads
2906   // Then thread t will start at region floor ((t * n) / p)
2907 
2908   result = g1_policy()->collection_set();
2909   if (G1CollectedHeap::use_parallel_gc_threads()) {
2910     uint cs_size = g1_policy()->cset_region_length();
2911     uint active_workers = workers()->active_workers();
2912     assert(UseDynamicNumberOfGCThreads ||
2913              active_workers == workers()->total_workers(),
2914              "Unless dynamic should use total workers");
2915 
2916     uint end_ind   = (cs_size * worker_i) / active_workers;
2917     uint start_ind = 0;
2918 
2919     if (worker_i > 0 &&
2920         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2921       // Previous workers starting region is valid
2922       // so let's iterate from there
2923       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2924       result = _worker_cset_start_region[worker_i - 1];
2925     }
2926 
2927     for (uint i = start_ind; i < end_ind; i++) {
2928       result = result->next_in_collection_set();
2929     }
2930   }
2931 
2932   // Note: the calculated starting heap region may be NULL
2933   // (when the collection set is empty).
2934   assert(result == NULL || result->in_collection_set(), "sanity");
2935   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2936          "should be updated only once per pause");
2937   _worker_cset_start_region[worker_i] = result;
2938   OrderAccess::storestore();
2939   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2940   return result;
2941 }
2942 
2943 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2944                                                      uint no_of_par_workers) {
2945   uint worker_num =
2946            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2947   assert(UseDynamicNumberOfGCThreads ||
2948          no_of_par_workers == workers()->total_workers(),
2949          "Non dynamic should use fixed number of workers");
2950   const uint start_index = n_regions() * worker_i / worker_num;
2951   return region_at(start_index);
2952 }
2953 
2954 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2955   HeapRegion* r = g1_policy()->collection_set();
2956   while (r != NULL) {
2957     HeapRegion* next = r->next_in_collection_set();
2958     if (cl->doHeapRegion(r)) {
2959       cl->incomplete();
2960       return;
2961     }
2962     r = next;
2963   }
2964 }
2965 
2966 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2967                                                   HeapRegionClosure *cl) {
2968   if (r == NULL) {
2969     // The CSet is empty so there's nothing to do.
2970     return;
2971   }
2972 
2973   assert(r->in_collection_set(),
2974          "Start region must be a member of the collection set.");
2975   HeapRegion* cur = r;
2976   while (cur != NULL) {
2977     HeapRegion* next = cur->next_in_collection_set();
2978     if (cl->doHeapRegion(cur) && false) {
2979       cl->incomplete();
2980       return;
2981     }
2982     cur = next;
2983   }
2984   cur = g1_policy()->collection_set();
2985   while (cur != r) {
2986     HeapRegion* next = cur->next_in_collection_set();
2987     if (cl->doHeapRegion(cur) && false) {
2988       cl->incomplete();
2989       return;
2990     }
2991     cur = next;
2992   }
2993 }
2994 
2995 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2996   return n_regions() > 0 ? region_at(0) : NULL;
2997 }
2998 
2999 
3000 Space* G1CollectedHeap::space_containing(const void* addr) const {
3001   Space* res = heap_region_containing(addr);
3002   return res;
3003 }
3004 
3005 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
3006   Space* sp = space_containing(addr);
3007   if (sp != NULL) {
3008     return sp->block_start(addr);
3009   }
3010   return NULL;
3011 }
3012 
3013 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3014   Space* sp = space_containing(addr);
3015   assert(sp != NULL, "block_size of address outside of heap");
3016   return sp->block_size(addr);
3017 }
3018 
3019 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3020   Space* sp = space_containing(addr);
3021   return sp->block_is_obj(addr);
3022 }
3023 
3024 bool G1CollectedHeap::supports_tlab_allocation() const {
3025   return true;
3026 }
3027 
3028 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3029   return HeapRegion::GrainBytes;
3030 }
3031 
3032 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3033   // Return the remaining space in the cur alloc region, but not less than
3034   // the min TLAB size.
3035 
3036   // Also, this value can be at most the humongous object threshold,
3037   // since we can't allow tlabs to grow big enough to accommodate
3038   // humongous objects.
3039 
3040   HeapRegion* hr = _mutator_alloc_region.get();
3041   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3042   if (hr == NULL) {
3043     return max_tlab_size;
3044   } else {
3045     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3046   }
3047 }
3048 
3049 size_t G1CollectedHeap::max_capacity() const {
3050   return _g1_reserved.byte_size();
3051 }
3052 
3053 jlong G1CollectedHeap::millis_since_last_gc() {
3054   // assert(false, "NYI");
3055   return 0;
3056 }
3057 
3058 void G1CollectedHeap::prepare_for_verify() {
3059   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3060     ensure_parsability(false);
3061   }
3062   g1_rem_set()->prepare_for_verify();
3063 }
3064 
3065 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3066                                               VerifyOption vo) {
3067   switch (vo) {
3068   case VerifyOption_G1UsePrevMarking:
3069     return hr->obj_allocated_since_prev_marking(obj);
3070   case VerifyOption_G1UseNextMarking:
3071     return hr->obj_allocated_since_next_marking(obj);
3072   case VerifyOption_G1UseMarkWord:
3073     return false;
3074   default:
3075     ShouldNotReachHere();
3076   }
3077   return false; // keep some compilers happy
3078 }
3079 
3080 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3081   switch (vo) {
3082   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3083   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3084   case VerifyOption_G1UseMarkWord:    return NULL;
3085   default:                            ShouldNotReachHere();
3086   }
3087   return NULL; // keep some compilers happy
3088 }
3089 
3090 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3091   switch (vo) {
3092   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3093   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3094   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3095   default:                            ShouldNotReachHere();
3096   }
3097   return false; // keep some compilers happy
3098 }
3099 
3100 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3101   switch (vo) {
3102   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3103   case VerifyOption_G1UseNextMarking: return "NTAMS";
3104   case VerifyOption_G1UseMarkWord:    return "NONE";
3105   default:                            ShouldNotReachHere();
3106   }
3107   return NULL; // keep some compilers happy
3108 }
3109 
3110 class VerifyLivenessOopClosure: public OopClosure {
3111   G1CollectedHeap* _g1h;
3112   VerifyOption _vo;
3113 public:
3114   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3115     _g1h(g1h), _vo(vo)
3116   { }
3117   void do_oop(narrowOop *p) { do_oop_work(p); }
3118   void do_oop(      oop *p) { do_oop_work(p); }
3119 
3120   template <class T> void do_oop_work(T *p) {
3121     oop obj = oopDesc::load_decode_heap_oop(p);
3122     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3123               "Dead object referenced by a not dead object");
3124   }
3125 };
3126 
3127 class VerifyObjsInRegionClosure: public ObjectClosure {
3128 private:
3129   G1CollectedHeap* _g1h;
3130   size_t _live_bytes;
3131   HeapRegion *_hr;
3132   VerifyOption _vo;
3133 public:
3134   // _vo == UsePrevMarking -> use "prev" marking information,
3135   // _vo == UseNextMarking -> use "next" marking information,
3136   // _vo == UseMarkWord    -> use mark word from object header.
3137   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3138     : _live_bytes(0), _hr(hr), _vo(vo) {
3139     _g1h = G1CollectedHeap::heap();
3140   }
3141   void do_object(oop o) {
3142     VerifyLivenessOopClosure isLive(_g1h, _vo);
3143     assert(o != NULL, "Huh?");
3144     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3145       // If the object is alive according to the mark word,
3146       // then verify that the marking information agrees.
3147       // Note we can't verify the contra-positive of the
3148       // above: if the object is dead (according to the mark
3149       // word), it may not be marked, or may have been marked
3150       // but has since became dead, or may have been allocated
3151       // since the last marking.
3152       if (_vo == VerifyOption_G1UseMarkWord) {
3153         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3154       }
3155 
3156       o->oop_iterate_no_header(&isLive);
3157       if (!_hr->obj_allocated_since_prev_marking(o)) {
3158         size_t obj_size = o->size();    // Make sure we don't overflow
3159         _live_bytes += (obj_size * HeapWordSize);
3160       }
3161     }
3162   }
3163   size_t live_bytes() { return _live_bytes; }
3164 };
3165 
3166 class PrintObjsInRegionClosure : public ObjectClosure {
3167   HeapRegion *_hr;
3168   G1CollectedHeap *_g1;
3169 public:
3170   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3171     _g1 = G1CollectedHeap::heap();
3172   };
3173 
3174   void do_object(oop o) {
3175     if (o != NULL) {
3176       HeapWord *start = (HeapWord *) o;
3177       size_t word_sz = o->size();
3178       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3179                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3180                           (void*) o, word_sz,
3181                           _g1->isMarkedPrev(o),
3182                           _g1->isMarkedNext(o),
3183                           _hr->obj_allocated_since_prev_marking(o));
3184       HeapWord *end = start + word_sz;
3185       HeapWord *cur;
3186       int *val;
3187       for (cur = start; cur < end; cur++) {
3188         val = (int *) cur;
3189         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3190       }
3191     }
3192   }
3193 };
3194 
3195 class VerifyRegionClosure: public HeapRegionClosure {
3196 private:
3197   bool             _par;
3198   VerifyOption     _vo;
3199   bool             _failures;
3200 public:
3201   // _vo == UsePrevMarking -> use "prev" marking information,
3202   // _vo == UseNextMarking -> use "next" marking information,
3203   // _vo == UseMarkWord    -> use mark word from object header.
3204   VerifyRegionClosure(bool par, VerifyOption vo)
3205     : _par(par),
3206       _vo(vo),
3207       _failures(false) {}
3208 
3209   bool failures() {
3210     return _failures;
3211   }
3212 
3213   bool doHeapRegion(HeapRegion* r) {
3214     if (!r->continuesHumongous()) {
3215       bool failures = false;
3216       r->verify(_vo, &failures);
3217       if (failures) {
3218         _failures = true;
3219       } else {
3220         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3221         r->object_iterate(&not_dead_yet_cl);
3222         if (_vo != VerifyOption_G1UseNextMarking) {
3223           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3224             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3225                                    "max_live_bytes "SIZE_FORMAT" "
3226                                    "< calculated "SIZE_FORMAT,
3227                                    r->bottom(), r->end(),
3228                                    r->max_live_bytes(),
3229                                  not_dead_yet_cl.live_bytes());
3230             _failures = true;
3231           }
3232         } else {
3233           // When vo == UseNextMarking we cannot currently do a sanity
3234           // check on the live bytes as the calculation has not been
3235           // finalized yet.
3236         }
3237       }
3238     }
3239     return false; // stop the region iteration if we hit a failure
3240   }
3241 };
3242 
3243 class YoungRefCounterClosure : public OopClosure {
3244   G1CollectedHeap* _g1h;
3245   int              _count;
3246  public:
3247   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3248   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3249   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3250 
3251   int count() { return _count; }
3252   void reset_count() { _count = 0; };
3253 };
3254 
3255 class VerifyKlassClosure: public KlassClosure {
3256   YoungRefCounterClosure _young_ref_counter_closure;
3257   OopClosure *_oop_closure;
3258  public:
3259   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3260   void do_klass(Klass* k) {
3261     k->oops_do(_oop_closure);
3262 
3263     _young_ref_counter_closure.reset_count();
3264     k->oops_do(&_young_ref_counter_closure);
3265     if (_young_ref_counter_closure.count() > 0) {
3266       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3267     }
3268   }
3269 };
3270 
3271 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3272 //       pass it as the perm_blk to SharedHeap::process_strong_roots.
3273 //       When process_strong_roots stop calling perm_blk->younger_refs_iterate
3274 //       we can change this closure to extend the simpler OopClosure.
3275 class VerifyRootsClosure: public OopsInGenClosure {
3276 private:
3277   G1CollectedHeap* _g1h;
3278   VerifyOption     _vo;
3279   bool             _failures;
3280 public:
3281   // _vo == UsePrevMarking -> use "prev" marking information,
3282   // _vo == UseNextMarking -> use "next" marking information,
3283   // _vo == UseMarkWord    -> use mark word from object header.
3284   VerifyRootsClosure(VerifyOption vo) :
3285     _g1h(G1CollectedHeap::heap()),
3286     _vo(vo),
3287     _failures(false) { }
3288 
3289   bool failures() { return _failures; }
3290 
3291   template <class T> void do_oop_nv(T* p) {
3292     T heap_oop = oopDesc::load_heap_oop(p);
3293     if (!oopDesc::is_null(heap_oop)) {
3294       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3295       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3296         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3297                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3298         if (_vo == VerifyOption_G1UseMarkWord) {
3299           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3300         }
3301         obj->print_on(gclog_or_tty);
3302         _failures = true;
3303       }
3304     }
3305   }
3306 
3307   void do_oop(oop* p)       { do_oop_nv(p); }
3308   void do_oop(narrowOop* p) { do_oop_nv(p); }
3309 };
3310 
3311 // This is the task used for parallel heap verification.
3312 
3313 class G1ParVerifyTask: public AbstractGangTask {
3314 private:
3315   G1CollectedHeap* _g1h;
3316   VerifyOption     _vo;
3317   bool             _failures;
3318 
3319 public:
3320   // _vo == UsePrevMarking -> use "prev" marking information,
3321   // _vo == UseNextMarking -> use "next" marking information,
3322   // _vo == UseMarkWord    -> use mark word from object header.
3323   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3324     AbstractGangTask("Parallel verify task"),
3325     _g1h(g1h),
3326     _vo(vo),
3327     _failures(false) { }
3328 
3329   bool failures() {
3330     return _failures;
3331   }
3332 
3333   void work(uint worker_id) {
3334     HandleMark hm;
3335     VerifyRegionClosure blk(true, _vo);
3336     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3337                                           _g1h->workers()->active_workers(),
3338                                           HeapRegion::ParVerifyClaimValue);
3339     if (blk.failures()) {
3340       _failures = true;
3341     }
3342   }
3343 };
3344 
3345 void G1CollectedHeap::verify(bool silent) {
3346   verify(silent, VerifyOption_G1UsePrevMarking);
3347 }
3348 
3349 void G1CollectedHeap::verify(bool silent,
3350                              VerifyOption vo) {
3351   if (SafepointSynchronize::is_at_safepoint()) {
3352     if (!silent) { gclog_or_tty->print("Roots "); }
3353     VerifyRootsClosure rootsCl(vo);
3354 
3355     assert(Thread::current()->is_VM_thread(),
3356            "Expected to be executed serially by the VM thread at this point");
3357 
3358     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3359     VerifyKlassClosure klassCl(this, &rootsCl);
3360 
3361     // We apply the relevant closures to all the oops in the
3362     // system dictionary, the string table and the code cache.
3363     const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3364 
3365     // Need cleared claim bits for the strong roots processing
3366     ClassLoaderDataGraph::clear_claimed_marks();
3367 
3368     process_strong_roots(true,      // activate StrongRootsScope
3369                          false,     // we set "is scavenging" to false,
3370                                     // so we don't reset the dirty cards.
3371                          ScanningOption(so),  // roots scanning options
3372                          &rootsCl,
3373                          &blobsCl,
3374                          &klassCl
3375                          );
3376 
3377     bool failures = rootsCl.failures();
3378 
3379     if (vo != VerifyOption_G1UseMarkWord) {
3380       // If we're verifying during a full GC then the region sets
3381       // will have been torn down at the start of the GC. Therefore
3382       // verifying the region sets will fail. So we only verify
3383       // the region sets when not in a full GC.
3384       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3385       verify_region_sets();
3386     }
3387 
3388     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3389     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3390       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3391              "sanity check");
3392 
3393       G1ParVerifyTask task(this, vo);
3394       assert(UseDynamicNumberOfGCThreads ||
3395         workers()->active_workers() == workers()->total_workers(),
3396         "If not dynamic should be using all the workers");
3397       int n_workers = workers()->active_workers();
3398       set_par_threads(n_workers);
3399       workers()->run_task(&task);
3400       set_par_threads(0);
3401       if (task.failures()) {
3402         failures = true;
3403       }
3404 
3405       // Checks that the expected amount of parallel work was done.
3406       // The implication is that n_workers is > 0.
3407       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3408              "sanity check");
3409 
3410       reset_heap_region_claim_values();
3411 
3412       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3413              "sanity check");
3414     } else {
3415       VerifyRegionClosure blk(false, vo);
3416       heap_region_iterate(&blk);
3417       if (blk.failures()) {
3418         failures = true;
3419       }
3420     }
3421     if (!silent) gclog_or_tty->print("RemSet ");
3422     rem_set()->verify();
3423 
3424     if (failures) {
3425       gclog_or_tty->print_cr("Heap:");
3426       // It helps to have the per-region information in the output to
3427       // help us track down what went wrong. This is why we call
3428       // print_extended_on() instead of print_on().
3429       print_extended_on(gclog_or_tty);
3430       gclog_or_tty->print_cr("");
3431 #ifndef PRODUCT
3432       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3433         concurrent_mark()->print_reachable("at-verification-failure",
3434                                            vo, false /* all */);
3435       }
3436 #endif
3437       gclog_or_tty->flush();
3438     }
3439     guarantee(!failures, "there should not have been any failures");
3440   } else {
3441     if (!silent)
3442       gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3443   }
3444 }
3445 
3446 class PrintRegionClosure: public HeapRegionClosure {
3447   outputStream* _st;
3448 public:
3449   PrintRegionClosure(outputStream* st) : _st(st) {}
3450   bool doHeapRegion(HeapRegion* r) {
3451     r->print_on(_st);
3452     return false;
3453   }
3454 };
3455 
3456 void G1CollectedHeap::print_on(outputStream* st) const {
3457   st->print(" %-20s", "garbage-first heap");
3458   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3459             capacity()/K, used_unlocked()/K);
3460   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3461             _g1_storage.low_boundary(),
3462             _g1_storage.high(),
3463             _g1_storage.high_boundary());
3464   st->cr();
3465   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3466   uint young_regions = _young_list->length();
3467   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3468             (size_t) young_regions * HeapRegion::GrainBytes / K);
3469   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3470   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3471             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3472   st->cr();
3473   MetaspaceAux::print_on(st);
3474 }
3475 
3476 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3477   print_on(st);
3478 
3479   // Print the per-region information.
3480   st->cr();
3481   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3482                "HS=humongous(starts), HC=humongous(continues), "
3483                "CS=collection set, F=free, TS=gc time stamp, "
3484                "PTAMS=previous top-at-mark-start, "
3485                "NTAMS=next top-at-mark-start)");
3486   PrintRegionClosure blk(st);
3487   heap_region_iterate(&blk);
3488 }
3489 
3490 void G1CollectedHeap::print_on_error(outputStream* st) const {
3491   this->CollectedHeap::print_on_error(st);
3492 
3493   if (_cm != NULL) {
3494     st->cr();
3495     _cm->print_on_error(st);
3496   }
3497 }
3498 
3499 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3500   if (G1CollectedHeap::use_parallel_gc_threads()) {
3501     workers()->print_worker_threads_on(st);
3502   }
3503   _cmThread->print_on(st);
3504   st->cr();
3505   _cm->print_worker_threads_on(st);
3506   _cg1r->print_worker_threads_on(st);
3507 }
3508 
3509 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3510   if (G1CollectedHeap::use_parallel_gc_threads()) {
3511     workers()->threads_do(tc);
3512   }
3513   tc->do_thread(_cmThread);
3514   _cg1r->threads_do(tc);
3515 }
3516 
3517 void G1CollectedHeap::print_tracing_info() const {
3518   // We'll overload this to mean "trace GC pause statistics."
3519   if (TraceGen0Time || TraceGen1Time) {
3520     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3521     // to that.
3522     g1_policy()->print_tracing_info();
3523   }
3524   if (G1SummarizeRSetStats) {
3525     g1_rem_set()->print_summary_info();
3526   }
3527   if (G1SummarizeConcMark) {
3528     concurrent_mark()->print_summary_info();
3529   }
3530   g1_policy()->print_yg_surv_rate_info();
3531   SpecializationStats::print();
3532 }
3533 
3534 #ifndef PRODUCT
3535 // Helpful for debugging RSet issues.
3536 
3537 class PrintRSetsClosure : public HeapRegionClosure {
3538 private:
3539   const char* _msg;
3540   size_t _occupied_sum;
3541 
3542 public:
3543   bool doHeapRegion(HeapRegion* r) {
3544     HeapRegionRemSet* hrrs = r->rem_set();
3545     size_t occupied = hrrs->occupied();
3546     _occupied_sum += occupied;
3547 
3548     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3549                            HR_FORMAT_PARAMS(r));
3550     if (occupied == 0) {
3551       gclog_or_tty->print_cr("  RSet is empty");
3552     } else {
3553       hrrs->print();
3554     }
3555     gclog_or_tty->print_cr("----------");
3556     return false;
3557   }
3558 
3559   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3560     gclog_or_tty->cr();
3561     gclog_or_tty->print_cr("========================================");
3562     gclog_or_tty->print_cr(msg);
3563     gclog_or_tty->cr();
3564   }
3565 
3566   ~PrintRSetsClosure() {
3567     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3568     gclog_or_tty->print_cr("========================================");
3569     gclog_or_tty->cr();
3570   }
3571 };
3572 
3573 void G1CollectedHeap::print_cset_rsets() {
3574   PrintRSetsClosure cl("Printing CSet RSets");
3575   collection_set_iterate(&cl);
3576 }
3577 
3578 void G1CollectedHeap::print_all_rsets() {
3579   PrintRSetsClosure cl("Printing All RSets");;
3580   heap_region_iterate(&cl);
3581 }
3582 #endif // PRODUCT
3583 
3584 G1CollectedHeap* G1CollectedHeap::heap() {
3585   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3586          "not a garbage-first heap");
3587   return _g1h;
3588 }
3589 
3590 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3591   // always_do_update_barrier = false;
3592   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3593   // Fill TLAB's and such
3594   ensure_parsability(true);
3595 }
3596 
3597 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3598 
3599   if (G1SummarizeRSetStats &&
3600       (G1SummarizeRSetStatsPeriod > 0) &&
3601       // we are at the end of the GC. Total collections has already been increased.
3602       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3603     g1_rem_set()->print_periodic_summary_info();
3604   }
3605 
3606   // FIXME: what is this about?
3607   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3608   // is set.
3609   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3610                         "derived pointer present"));
3611   // always_do_update_barrier = true;
3612 
3613   // We have just completed a GC. Update the soft reference
3614   // policy with the new heap occupancy
3615   Universe::update_heap_info_at_gc();
3616 }
3617 
3618 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3619                                                unsigned int gc_count_before,
3620                                                bool* succeeded) {
3621   assert_heap_not_locked_and_not_at_safepoint();
3622   g1_policy()->record_stop_world_start();
3623   VM_G1IncCollectionPause op(gc_count_before,
3624                              word_size,
3625                              false, /* should_initiate_conc_mark */
3626                              g1_policy()->max_pause_time_ms(),
3627                              GCCause::_g1_inc_collection_pause);
3628   VMThread::execute(&op);
3629 
3630   HeapWord* result = op.result();
3631   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3632   assert(result == NULL || ret_succeeded,
3633          "the result should be NULL if the VM did not succeed");
3634   *succeeded = ret_succeeded;
3635 
3636   assert_heap_not_locked();
3637   return result;
3638 }
3639 
3640 void
3641 G1CollectedHeap::doConcurrentMark() {
3642   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3643   if (!_cmThread->in_progress()) {
3644     _cmThread->set_started();
3645     CGC_lock->notify();
3646   }
3647 }
3648 
3649 size_t G1CollectedHeap::pending_card_num() {
3650   size_t extra_cards = 0;
3651   JavaThread *curr = Threads::first();
3652   while (curr != NULL) {
3653     DirtyCardQueue& dcq = curr->dirty_card_queue();
3654     extra_cards += dcq.size();
3655     curr = curr->next();
3656   }
3657   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3658   size_t buffer_size = dcqs.buffer_size();
3659   size_t buffer_num = dcqs.completed_buffers_num();
3660 
3661   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3662   // in bytes - not the number of 'entries'. We need to convert
3663   // into a number of cards.
3664   return (buffer_size * buffer_num + extra_cards) / oopSize;
3665 }
3666 
3667 size_t G1CollectedHeap::cards_scanned() {
3668   return g1_rem_set()->cardsScanned();
3669 }
3670 
3671 void
3672 G1CollectedHeap::setup_surviving_young_words() {
3673   assert(_surviving_young_words == NULL, "pre-condition");
3674   uint array_length = g1_policy()->young_cset_region_length();
3675   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3676   if (_surviving_young_words == NULL) {
3677     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3678                           "Not enough space for young surv words summary.");
3679   }
3680   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3681 #ifdef ASSERT
3682   for (uint i = 0;  i < array_length; ++i) {
3683     assert( _surviving_young_words[i] == 0, "memset above" );
3684   }
3685 #endif // !ASSERT
3686 }
3687 
3688 void
3689 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3690   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3691   uint array_length = g1_policy()->young_cset_region_length();
3692   for (uint i = 0; i < array_length; ++i) {
3693     _surviving_young_words[i] += surv_young_words[i];
3694   }
3695 }
3696 
3697 void
3698 G1CollectedHeap::cleanup_surviving_young_words() {
3699   guarantee( _surviving_young_words != NULL, "pre-condition" );
3700   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3701   _surviving_young_words = NULL;
3702 }
3703 
3704 #ifdef ASSERT
3705 class VerifyCSetClosure: public HeapRegionClosure {
3706 public:
3707   bool doHeapRegion(HeapRegion* hr) {
3708     // Here we check that the CSet region's RSet is ready for parallel
3709     // iteration. The fields that we'll verify are only manipulated
3710     // when the region is part of a CSet and is collected. Afterwards,
3711     // we reset these fields when we clear the region's RSet (when the
3712     // region is freed) so they are ready when the region is
3713     // re-allocated. The only exception to this is if there's an
3714     // evacuation failure and instead of freeing the region we leave
3715     // it in the heap. In that case, we reset these fields during
3716     // evacuation failure handling.
3717     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3718 
3719     // Here's a good place to add any other checks we'd like to
3720     // perform on CSet regions.
3721     return false;
3722   }
3723 };
3724 #endif // ASSERT
3725 
3726 #if TASKQUEUE_STATS
3727 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3728   st->print_raw_cr("GC Task Stats");
3729   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3730   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3731 }
3732 
3733 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3734   print_taskqueue_stats_hdr(st);
3735 
3736   TaskQueueStats totals;
3737   const int n = workers() != NULL ? workers()->total_workers() : 1;
3738   for (int i = 0; i < n; ++i) {
3739     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3740     totals += task_queue(i)->stats;
3741   }
3742   st->print_raw("tot "); totals.print(st); st->cr();
3743 
3744   DEBUG_ONLY(totals.verify());
3745 }
3746 
3747 void G1CollectedHeap::reset_taskqueue_stats() {
3748   const int n = workers() != NULL ? workers()->total_workers() : 1;
3749   for (int i = 0; i < n; ++i) {
3750     task_queue(i)->stats.reset();
3751   }
3752 }
3753 #endif // TASKQUEUE_STATS
3754 
3755 void G1CollectedHeap::log_gc_header() {
3756   if (!G1Log::fine()) {
3757     return;
3758   }
3759 
3760   gclog_or_tty->date_stamp(PrintGCDateStamps);
3761   gclog_or_tty->stamp(PrintGCTimeStamps);
3762 
3763   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3764     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3765     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3766 
3767   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3768 }
3769 
3770 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3771   if (!G1Log::fine()) {
3772     return;
3773   }
3774 
3775   if (G1Log::finer()) {
3776     if (evacuation_failed()) {
3777       gclog_or_tty->print(" (to-space exhausted)");
3778     }
3779     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3780     g1_policy()->phase_times()->note_gc_end();
3781     g1_policy()->phase_times()->print(pause_time_sec);
3782     g1_policy()->print_detailed_heap_transition();
3783   } else {
3784     if (evacuation_failed()) {
3785       gclog_or_tty->print("--");
3786     }
3787     g1_policy()->print_heap_transition();
3788     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3789   }
3790   gclog_or_tty->flush();
3791 }
3792 
3793 bool
3794 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3795   assert_at_safepoint(true /* should_be_vm_thread */);
3796   guarantee(!is_gc_active(), "collection is not reentrant");
3797 
3798   if (GC_locker::check_active_before_gc()) {
3799     return false;
3800   }
3801 
3802   _gc_timer_stw->register_gc_start(os::elapsed_counter());
3803 
3804   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3805 
3806   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3807   ResourceMark rm;
3808 
3809   print_heap_before_gc();
3810   trace_heap_before_gc(_gc_tracer_stw);
3811 
3812   HRSPhaseSetter x(HRSPhaseEvacuation);
3813   verify_region_sets_optional();
3814   verify_dirty_young_regions();
3815 
3816   // This call will decide whether this pause is an initial-mark
3817   // pause. If it is, during_initial_mark_pause() will return true
3818   // for the duration of this pause.
3819   g1_policy()->decide_on_conc_mark_initiation();
3820 
3821   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3822   assert(!g1_policy()->during_initial_mark_pause() ||
3823           g1_policy()->gcs_are_young(), "sanity");
3824 
3825   // We also do not allow mixed GCs during marking.
3826   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3827 
3828   // Record whether this pause is an initial mark. When the current
3829   // thread has completed its logging output and it's safe to signal
3830   // the CM thread, the flag's value in the policy has been reset.
3831   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3832 
3833   // Inner scope for scope based logging, timers, and stats collection
3834   {
3835     EvacuationInfo evacuation_info;
3836 
3837     if (g1_policy()->during_initial_mark_pause()) {
3838       // We are about to start a marking cycle, so we increment the
3839       // full collection counter.
3840       increment_old_marking_cycles_started();
3841       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3842     }
3843 
3844     _gc_tracer_stw->report_yc_type(yc_type());
3845 
3846     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3847 
3848     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3849                                 workers()->active_workers() : 1);
3850     double pause_start_sec = os::elapsedTime();
3851     g1_policy()->phase_times()->note_gc_start(active_workers);
3852     log_gc_header();
3853 
3854     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3855     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3856 
3857     // If the secondary_free_list is not empty, append it to the
3858     // free_list. No need to wait for the cleanup operation to finish;
3859     // the region allocation code will check the secondary_free_list
3860     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3861     // set, skip this step so that the region allocation code has to
3862     // get entries from the secondary_free_list.
3863     if (!G1StressConcRegionFreeing) {
3864       append_secondary_free_list_if_not_empty_with_lock();
3865     }
3866 
3867     assert(check_young_list_well_formed(),
3868       "young list should be well formed");
3869 
3870     // Don't dynamically change the number of GC threads this early.  A value of
3871     // 0 is used to indicate serial work.  When parallel work is done,
3872     // it will be set.
3873 
3874     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3875       IsGCActiveMark x;
3876 
3877       gc_prologue(false);
3878       increment_total_collections(false /* full gc */);
3879       increment_gc_time_stamp();
3880 
3881       verify_before_gc();
3882 
3883       COMPILER2_PRESENT(DerivedPointerTable::clear());
3884 
3885       // Please see comment in g1CollectedHeap.hpp and
3886       // G1CollectedHeap::ref_processing_init() to see how
3887       // reference processing currently works in G1.
3888 
3889       // Enable discovery in the STW reference processor
3890       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3891                                             true /*verify_no_refs*/);
3892 
3893       {
3894         // We want to temporarily turn off discovery by the
3895         // CM ref processor, if necessary, and turn it back on
3896         // on again later if we do. Using a scoped
3897         // NoRefDiscovery object will do this.
3898         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3899 
3900         // Forget the current alloc region (we might even choose it to be part
3901         // of the collection set!).
3902         release_mutator_alloc_region();
3903 
3904         // We should call this after we retire the mutator alloc
3905         // region(s) so that all the ALLOC / RETIRE events are generated
3906         // before the start GC event.
3907         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3908 
3909         // This timing is only used by the ergonomics to handle our pause target.
3910         // It is unclear why this should not include the full pause. We will
3911         // investigate this in CR 7178365.
3912         //
3913         // Preserving the old comment here if that helps the investigation:
3914         //
3915         // The elapsed time induced by the start time below deliberately elides
3916         // the possible verification above.
3917         double sample_start_time_sec = os::elapsedTime();
3918 
3919 #if YOUNG_LIST_VERBOSE
3920         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3921         _young_list->print();
3922         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3923 #endif // YOUNG_LIST_VERBOSE
3924 
3925         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3926 
3927         double scan_wait_start = os::elapsedTime();
3928         // We have to wait until the CM threads finish scanning the
3929         // root regions as it's the only way to ensure that all the
3930         // objects on them have been correctly scanned before we start
3931         // moving them during the GC.
3932         bool waited = _cm->root_regions()->wait_until_scan_finished();
3933         double wait_time_ms = 0.0;
3934         if (waited) {
3935           double scan_wait_end = os::elapsedTime();
3936           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3937         }
3938         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3939 
3940 #if YOUNG_LIST_VERBOSE
3941         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3942         _young_list->print();
3943 #endif // YOUNG_LIST_VERBOSE
3944 
3945         if (g1_policy()->during_initial_mark_pause()) {
3946           concurrent_mark()->checkpointRootsInitialPre();
3947         }
3948 
3949 #if YOUNG_LIST_VERBOSE
3950         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3951         _young_list->print();
3952         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3953 #endif // YOUNG_LIST_VERBOSE
3954 
3955         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3956 
3957         _cm->note_start_of_gc();
3958         // We should not verify the per-thread SATB buffers given that
3959         // we have not filtered them yet (we'll do so during the
3960         // GC). We also call this after finalize_cset() to
3961         // ensure that the CSet has been finalized.
3962         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3963                                  true  /* verify_enqueued_buffers */,
3964                                  false /* verify_thread_buffers */,
3965                                  true  /* verify_fingers */);
3966 
3967         if (_hr_printer.is_active()) {
3968           HeapRegion* hr = g1_policy()->collection_set();
3969           while (hr != NULL) {
3970             G1HRPrinter::RegionType type;
3971             if (!hr->is_young()) {
3972               type = G1HRPrinter::Old;
3973             } else if (hr->is_survivor()) {
3974               type = G1HRPrinter::Survivor;
3975             } else {
3976               type = G1HRPrinter::Eden;
3977             }
3978             _hr_printer.cset(hr);
3979             hr = hr->next_in_collection_set();
3980           }
3981         }
3982 
3983 #ifdef ASSERT
3984         VerifyCSetClosure cl;
3985         collection_set_iterate(&cl);
3986 #endif // ASSERT
3987 
3988         setup_surviving_young_words();
3989 
3990         // Initialize the GC alloc regions.
3991         init_gc_alloc_regions(evacuation_info);
3992 
3993         // Actually do the work...
3994         evacuate_collection_set(evacuation_info);
3995 
3996         // We do this to mainly verify the per-thread SATB buffers
3997         // (which have been filtered by now) since we didn't verify
3998         // them earlier. No point in re-checking the stacks / enqueued
3999         // buffers given that the CSet has not changed since last time
4000         // we checked.
4001         _cm->verify_no_cset_oops(false /* verify_stacks */,
4002                                  false /* verify_enqueued_buffers */,
4003                                  true  /* verify_thread_buffers */,
4004                                  true  /* verify_fingers */);
4005 
4006         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4007         g1_policy()->clear_collection_set();
4008 
4009         cleanup_surviving_young_words();
4010 
4011         // Start a new incremental collection set for the next pause.
4012         g1_policy()->start_incremental_cset_building();
4013 
4014         // Clear the _cset_fast_test bitmap in anticipation of adding
4015         // regions to the incremental collection set for the next
4016         // evacuation pause.
4017         clear_cset_fast_test();
4018 
4019         _young_list->reset_sampled_info();
4020 
4021         // Don't check the whole heap at this point as the
4022         // GC alloc regions from this pause have been tagged
4023         // as survivors and moved on to the survivor list.
4024         // Survivor regions will fail the !is_young() check.
4025         assert(check_young_list_empty(false /* check_heap */),
4026           "young list should be empty");
4027 
4028 #if YOUNG_LIST_VERBOSE
4029         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4030         _young_list->print();
4031 #endif // YOUNG_LIST_VERBOSE
4032 
4033         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4034                                              _young_list->first_survivor_region(),
4035                                              _young_list->last_survivor_region());
4036 
4037         _young_list->reset_auxilary_lists();
4038 
4039         if (evacuation_failed()) {
4040           _summary_bytes_used = recalculate_used();
4041           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4042           for (uint i = 0; i < n_queues; i++) {
4043             if (_evacuation_failed_info_array[i].has_failed()) {
4044               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4045             }
4046           }
4047         } else {
4048           // The "used" of the the collection set have already been subtracted
4049           // when they were freed.  Add in the bytes evacuated.
4050           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4051         }
4052 
4053         if (g1_policy()->during_initial_mark_pause()) {
4054           // We have to do this before we notify the CM threads that
4055           // they can start working to make sure that all the
4056           // appropriate initialization is done on the CM object.
4057           concurrent_mark()->checkpointRootsInitialPost();
4058           set_marking_started();
4059           // Note that we don't actually trigger the CM thread at
4060           // this point. We do that later when we're sure that
4061           // the current thread has completed its logging output.
4062         }
4063 
4064         allocate_dummy_regions();
4065 
4066 #if YOUNG_LIST_VERBOSE
4067         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4068         _young_list->print();
4069         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4070 #endif // YOUNG_LIST_VERBOSE
4071 
4072         init_mutator_alloc_region();
4073 
4074         {
4075           size_t expand_bytes = g1_policy()->expansion_amount();
4076           if (expand_bytes > 0) {
4077             size_t bytes_before = capacity();
4078             // No need for an ergo verbose message here,
4079             // expansion_amount() does this when it returns a value > 0.
4080             if (!expand(expand_bytes)) {
4081               // We failed to expand the heap so let's verify that
4082               // committed/uncommitted amount match the backing store
4083               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4084               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4085             }
4086           }
4087         }
4088 
4089         // We redo the verification but now wrt to the new CSet which
4090         // has just got initialized after the previous CSet was freed.
4091         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4092                                  true  /* verify_enqueued_buffers */,
4093                                  true  /* verify_thread_buffers */,
4094                                  true  /* verify_fingers */);
4095         _cm->note_end_of_gc();
4096 
4097         // This timing is only used by the ergonomics to handle our pause target.
4098         // It is unclear why this should not include the full pause. We will
4099         // investigate this in CR 7178365.
4100         double sample_end_time_sec = os::elapsedTime();
4101         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4102         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4103 
4104         MemoryService::track_memory_usage();
4105 
4106         // In prepare_for_verify() below we'll need to scan the deferred
4107         // update buffers to bring the RSets up-to-date if
4108         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4109         // the update buffers we'll probably need to scan cards on the
4110         // regions we just allocated to (i.e., the GC alloc
4111         // regions). However, during the last GC we called
4112         // set_saved_mark() on all the GC alloc regions, so card
4113         // scanning might skip the [saved_mark_word()...top()] area of
4114         // those regions (i.e., the area we allocated objects into
4115         // during the last GC). But it shouldn't. Given that
4116         // saved_mark_word() is conditional on whether the GC time stamp
4117         // on the region is current or not, by incrementing the GC time
4118         // stamp here we invalidate all the GC time stamps on all the
4119         // regions and saved_mark_word() will simply return top() for
4120         // all the regions. This is a nicer way of ensuring this rather
4121         // than iterating over the regions and fixing them. In fact, the
4122         // GC time stamp increment here also ensures that
4123         // saved_mark_word() will return top() between pauses, i.e.,
4124         // during concurrent refinement. So we don't need the
4125         // is_gc_active() check to decided which top to use when
4126         // scanning cards (see CR 7039627).
4127         increment_gc_time_stamp();
4128 
4129         verify_after_gc();
4130 
4131         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4132         ref_processor_stw()->verify_no_references_recorded();
4133 
4134         // CM reference discovery will be re-enabled if necessary.
4135       }
4136 
4137       // We should do this after we potentially expand the heap so
4138       // that all the COMMIT events are generated before the end GC
4139       // event, and after we retire the GC alloc regions so that all
4140       // RETIRE events are generated before the end GC event.
4141       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4142 
4143       if (mark_in_progress()) {
4144         concurrent_mark()->update_g1_committed();
4145       }
4146 
4147 #ifdef TRACESPINNING
4148       ParallelTaskTerminator::print_termination_counts();
4149 #endif
4150 
4151       gc_epilogue(false);
4152     }
4153 
4154     // Print the remainder of the GC log output.
4155     log_gc_footer(os::elapsedTime() - pause_start_sec);
4156 
4157     // It is not yet to safe to tell the concurrent mark to
4158     // start as we have some optional output below. We don't want the
4159     // output from the concurrent mark thread interfering with this
4160     // logging output either.
4161 
4162     _hrs.verify_optional();
4163     verify_region_sets_optional();
4164 
4165     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4166     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4167 
4168     print_heap_after_gc();
4169     trace_heap_after_gc(_gc_tracer_stw);
4170 
4171     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4172     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4173     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4174     // before any GC notifications are raised.
4175     g1mm()->update_sizes();
4176 
4177     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4178     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4179     _gc_timer_stw->register_gc_end(os::elapsed_counter());
4180     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4181   }
4182   // It should now be safe to tell the concurrent mark thread to start
4183   // without its logging output interfering with the logging output
4184   // that came from the pause.
4185 
4186   if (should_start_conc_mark) {
4187     // CAUTION: after the doConcurrentMark() call below,
4188     // the concurrent marking thread(s) could be running
4189     // concurrently with us. Make sure that anything after
4190     // this point does not assume that we are the only GC thread
4191     // running. Note: of course, the actual marking work will
4192     // not start until the safepoint itself is released in
4193     // ConcurrentGCThread::safepoint_desynchronize().
4194     doConcurrentMark();
4195   }
4196 
4197   return true;
4198 }
4199 
4200 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4201 {
4202   size_t gclab_word_size;
4203   switch (purpose) {
4204     case GCAllocForSurvived:
4205       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4206       break;
4207     case GCAllocForTenured:
4208       gclab_word_size = _old_plab_stats.desired_plab_sz();
4209       break;
4210     default:
4211       assert(false, "unknown GCAllocPurpose");
4212       gclab_word_size = _old_plab_stats.desired_plab_sz();
4213       break;
4214   }
4215 
4216   // Prevent humongous PLAB sizes for two reasons:
4217   // * PLABs are allocated using a similar paths as oops, but should
4218   //   never be in a humongous region
4219   // * Allowing humongous PLABs needlessly churns the region free lists
4220   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4221 }
4222 
4223 void G1CollectedHeap::init_mutator_alloc_region() {
4224   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4225   _mutator_alloc_region.init();
4226 }
4227 
4228 void G1CollectedHeap::release_mutator_alloc_region() {
4229   _mutator_alloc_region.release();
4230   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4231 }
4232 
4233 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4234   assert_at_safepoint(true /* should_be_vm_thread */);
4235 
4236   _survivor_gc_alloc_region.init();
4237   _old_gc_alloc_region.init();
4238   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4239   _retained_old_gc_alloc_region = NULL;
4240 
4241   // We will discard the current GC alloc region if:
4242   // a) it's in the collection set (it can happen!),
4243   // b) it's already full (no point in using it),
4244   // c) it's empty (this means that it was emptied during
4245   // a cleanup and it should be on the free list now), or
4246   // d) it's humongous (this means that it was emptied
4247   // during a cleanup and was added to the free list, but
4248   // has been subsequently used to allocate a humongous
4249   // object that may be less than the region size).
4250   if (retained_region != NULL &&
4251       !retained_region->in_collection_set() &&
4252       !(retained_region->top() == retained_region->end()) &&
4253       !retained_region->is_empty() &&
4254       !retained_region->isHumongous()) {
4255     retained_region->set_saved_mark();
4256     // The retained region was added to the old region set when it was
4257     // retired. We have to remove it now, since we don't allow regions
4258     // we allocate to in the region sets. We'll re-add it later, when
4259     // it's retired again.
4260     _old_set.remove(retained_region);
4261     bool during_im = g1_policy()->during_initial_mark_pause();
4262     retained_region->note_start_of_copying(during_im);
4263     _old_gc_alloc_region.set(retained_region);
4264     _hr_printer.reuse(retained_region);
4265     evacuation_info.set_alloc_regions_used_before(retained_region->used());
4266   }
4267 }
4268 
4269 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4270   evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4271                                          _old_gc_alloc_region.count());
4272   _survivor_gc_alloc_region.release();
4273   // If we have an old GC alloc region to release, we'll save it in
4274   // _retained_old_gc_alloc_region. If we don't
4275   // _retained_old_gc_alloc_region will become NULL. This is what we
4276   // want either way so no reason to check explicitly for either
4277   // condition.
4278   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4279 
4280   if (ResizePLAB) {
4281     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4282     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4283   }
4284 }
4285 
4286 void G1CollectedHeap::abandon_gc_alloc_regions() {
4287   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4288   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4289   _retained_old_gc_alloc_region = NULL;
4290 }
4291 
4292 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4293   _drain_in_progress = false;
4294   set_evac_failure_closure(cl);
4295   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4296 }
4297 
4298 void G1CollectedHeap::finalize_for_evac_failure() {
4299   assert(_evac_failure_scan_stack != NULL &&
4300          _evac_failure_scan_stack->length() == 0,
4301          "Postcondition");
4302   assert(!_drain_in_progress, "Postcondition");
4303   delete _evac_failure_scan_stack;
4304   _evac_failure_scan_stack = NULL;
4305 }
4306 
4307 void G1CollectedHeap::remove_self_forwarding_pointers() {
4308   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4309 
4310   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4311 
4312   if (G1CollectedHeap::use_parallel_gc_threads()) {
4313     set_par_threads();
4314     workers()->run_task(&rsfp_task);
4315     set_par_threads(0);
4316   } else {
4317     rsfp_task.work(0);
4318   }
4319 
4320   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4321 
4322   // Reset the claim values in the regions in the collection set.
4323   reset_cset_heap_region_claim_values();
4324 
4325   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4326 
4327   // Now restore saved marks, if any.
4328   assert(_objs_with_preserved_marks.size() ==
4329             _preserved_marks_of_objs.size(), "Both or none.");
4330   while (!_objs_with_preserved_marks.is_empty()) {
4331     oop obj = _objs_with_preserved_marks.pop();
4332     markOop m = _preserved_marks_of_objs.pop();
4333     obj->set_mark(m);
4334   }
4335   _objs_with_preserved_marks.clear(true);
4336   _preserved_marks_of_objs.clear(true);
4337 }
4338 
4339 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4340   _evac_failure_scan_stack->push(obj);
4341 }
4342 
4343 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4344   assert(_evac_failure_scan_stack != NULL, "precondition");
4345 
4346   while (_evac_failure_scan_stack->length() > 0) {
4347      oop obj = _evac_failure_scan_stack->pop();
4348      _evac_failure_closure->set_region(heap_region_containing(obj));
4349      obj->oop_iterate_backwards(_evac_failure_closure);
4350   }
4351 }
4352 
4353 oop
4354 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4355                                                oop old) {
4356   assert(obj_in_cs(old),
4357          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4358                  (HeapWord*) old));
4359   markOop m = old->mark();
4360   oop forward_ptr = old->forward_to_atomic(old);
4361   if (forward_ptr == NULL) {
4362     // Forward-to-self succeeded.
4363     assert(_par_scan_state != NULL, "par scan state");
4364     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4365     uint queue_num = _par_scan_state->queue_num();
4366 
4367     _evacuation_failed = true;
4368     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4369     if (_evac_failure_closure != cl) {
4370       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4371       assert(!_drain_in_progress,
4372              "Should only be true while someone holds the lock.");
4373       // Set the global evac-failure closure to the current thread's.
4374       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4375       set_evac_failure_closure(cl);
4376       // Now do the common part.
4377       handle_evacuation_failure_common(old, m);
4378       // Reset to NULL.
4379       set_evac_failure_closure(NULL);
4380     } else {
4381       // The lock is already held, and this is recursive.
4382       assert(_drain_in_progress, "This should only be the recursive case.");
4383       handle_evacuation_failure_common(old, m);
4384     }
4385     return old;
4386   } else {
4387     // Forward-to-self failed. Either someone else managed to allocate
4388     // space for this object (old != forward_ptr) or they beat us in
4389     // self-forwarding it (old == forward_ptr).
4390     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4391            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4392                    "should not be in the CSet",
4393                    (HeapWord*) old, (HeapWord*) forward_ptr));
4394     return forward_ptr;
4395   }
4396 }
4397 
4398 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4399   preserve_mark_if_necessary(old, m);
4400 
4401   HeapRegion* r = heap_region_containing(old);
4402   if (!r->evacuation_failed()) {
4403     r->set_evacuation_failed(true);
4404     _hr_printer.evac_failure(r);
4405   }
4406 
4407   push_on_evac_failure_scan_stack(old);
4408 
4409   if (!_drain_in_progress) {
4410     // prevent recursion in copy_to_survivor_space()
4411     _drain_in_progress = true;
4412     drain_evac_failure_scan_stack();
4413     _drain_in_progress = false;
4414   }
4415 }
4416 
4417 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4418   assert(evacuation_failed(), "Oversaving!");
4419   // We want to call the "for_promotion_failure" version only in the
4420   // case of a promotion failure.
4421   if (m->must_be_preserved_for_promotion_failure(obj)) {
4422     _objs_with_preserved_marks.push(obj);
4423     _preserved_marks_of_objs.push(m);
4424   }
4425 }
4426 
4427 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4428                                                   size_t word_size) {
4429   if (purpose == GCAllocForSurvived) {
4430     HeapWord* result = survivor_attempt_allocation(word_size);
4431     if (result != NULL) {
4432       return result;
4433     } else {
4434       // Let's try to allocate in the old gen in case we can fit the
4435       // object there.
4436       return old_attempt_allocation(word_size);
4437     }
4438   } else {
4439     assert(purpose ==  GCAllocForTenured, "sanity");
4440     HeapWord* result = old_attempt_allocation(word_size);
4441     if (result != NULL) {
4442       return result;
4443     } else {
4444       // Let's try to allocate in the survivors in case we can fit the
4445       // object there.
4446       return survivor_attempt_allocation(word_size);
4447     }
4448   }
4449 
4450   ShouldNotReachHere();
4451   // Trying to keep some compilers happy.
4452   return NULL;
4453 }
4454 
4455 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4456   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4457 
4458 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4459   : _g1h(g1h),
4460     _refs(g1h->task_queue(queue_num)),
4461     _dcq(&g1h->dirty_card_queue_set()),
4462     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4463     _g1_rem(g1h->g1_rem_set()),
4464     _hash_seed(17), _queue_num(queue_num),
4465     _term_attempts(0),
4466     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4467     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4468     _age_table(false),
4469     _strong_roots_time(0), _term_time(0),
4470     _alloc_buffer_waste(0), _undo_waste(0) {
4471   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4472   // we "sacrifice" entry 0 to keep track of surviving bytes for
4473   // non-young regions (where the age is -1)
4474   // We also add a few elements at the beginning and at the end in
4475   // an attempt to eliminate cache contention
4476   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4477   uint array_length = PADDING_ELEM_NUM +
4478                       real_length +
4479                       PADDING_ELEM_NUM;
4480   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4481   if (_surviving_young_words_base == NULL)
4482     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4483                           "Not enough space for young surv histo.");
4484   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4485   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4486 
4487   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4488   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4489 
4490   _start = os::elapsedTime();
4491 }
4492 
4493 void
4494 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4495 {
4496   st->print_raw_cr("GC Termination Stats");
4497   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4498                    " ------waste (KiB)------");
4499   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4500                    "  total   alloc    undo");
4501   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4502                    " ------- ------- -------");
4503 }
4504 
4505 void
4506 G1ParScanThreadState::print_termination_stats(int i,
4507                                               outputStream* const st) const
4508 {
4509   const double elapsed_ms = elapsed_time() * 1000.0;
4510   const double s_roots_ms = strong_roots_time() * 1000.0;
4511   const double term_ms    = term_time() * 1000.0;
4512   st->print_cr("%3d %9.2f %9.2f %6.2f "
4513                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4514                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4515                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4516                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4517                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4518                alloc_buffer_waste() * HeapWordSize / K,
4519                undo_waste() * HeapWordSize / K);
4520 }
4521 
4522 #ifdef ASSERT
4523 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4524   assert(ref != NULL, "invariant");
4525   assert(UseCompressedOops, "sanity");
4526   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4527   oop p = oopDesc::load_decode_heap_oop(ref);
4528   assert(_g1h->is_in_g1_reserved(p),
4529          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4530   return true;
4531 }
4532 
4533 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4534   assert(ref != NULL, "invariant");
4535   if (has_partial_array_mask(ref)) {
4536     // Must be in the collection set--it's already been copied.
4537     oop p = clear_partial_array_mask(ref);
4538     assert(_g1h->obj_in_cs(p),
4539            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4540   } else {
4541     oop p = oopDesc::load_decode_heap_oop(ref);
4542     assert(_g1h->is_in_g1_reserved(p),
4543            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4544   }
4545   return true;
4546 }
4547 
4548 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4549   if (ref.is_narrow()) {
4550     return verify_ref((narrowOop*) ref);
4551   } else {
4552     return verify_ref((oop*) ref);
4553   }
4554 }
4555 #endif // ASSERT
4556 
4557 void G1ParScanThreadState::trim_queue() {
4558   assert(_evac_cl != NULL, "not set");
4559   assert(_evac_failure_cl != NULL, "not set");
4560   assert(_partial_scan_cl != NULL, "not set");
4561 
4562   StarTask ref;
4563   do {
4564     // Drain the overflow stack first, so other threads can steal.
4565     while (refs()->pop_overflow(ref)) {
4566       deal_with_reference(ref);
4567     }
4568 
4569     while (refs()->pop_local(ref)) {
4570       deal_with_reference(ref);
4571     }
4572   } while (!refs()->is_empty());
4573 }
4574 
4575 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4576                                      G1ParScanThreadState* par_scan_state) :
4577   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4578   _par_scan_state(par_scan_state),
4579   _worker_id(par_scan_state->queue_num()),
4580   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4581   _mark_in_progress(_g1->mark_in_progress()) { }
4582 
4583 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4584 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4585 #ifdef ASSERT
4586   HeapRegion* hr = _g1->heap_region_containing(obj);
4587   assert(hr != NULL, "sanity");
4588   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4589 #endif // ASSERT
4590 
4591   // We know that the object is not moving so it's safe to read its size.
4592   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4593 }
4594 
4595 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4596 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4597   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4598 #ifdef ASSERT
4599   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4600   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4601   assert(from_obj != to_obj, "should not be self-forwarded");
4602 
4603   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4604   assert(from_hr != NULL, "sanity");
4605   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4606 
4607   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4608   assert(to_hr != NULL, "sanity");
4609   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4610 #endif // ASSERT
4611 
4612   // The object might be in the process of being copied by another
4613   // worker so we cannot trust that its to-space image is
4614   // well-formed. So we have to read its size from its from-space
4615   // image which we know should not be changing.
4616   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4617 }
4618 
4619 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4620 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4621   ::copy_to_survivor_space(oop old) {
4622   size_t word_sz = old->size();
4623   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4624   // +1 to make the -1 indexes valid...
4625   int       young_index = from_region->young_index_in_cset()+1;
4626   assert( (from_region->is_young() && young_index >  0) ||
4627          (!from_region->is_young() && young_index == 0), "invariant" );
4628   G1CollectorPolicy* g1p = _g1->g1_policy();
4629   markOop m = old->mark();
4630   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4631                                            : m->age();
4632   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4633                                                              word_sz);
4634   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4635 #ifndef PRODUCT
4636   // Should this evacuation fail?
4637   if (_g1->evacuation_should_fail()) {
4638     if (obj_ptr != NULL) {
4639       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4640       obj_ptr = NULL;
4641     }
4642   }
4643 #endif // !PRODUCT
4644 
4645   if (obj_ptr == NULL) {
4646     // This will either forward-to-self, or detect that someone else has
4647     // installed a forwarding pointer.
4648     return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4649   }
4650 
4651   oop obj = oop(obj_ptr);
4652 
4653   // We're going to allocate linearly, so might as well prefetch ahead.
4654   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4655 
4656   oop forward_ptr = old->forward_to_atomic(obj);
4657   if (forward_ptr == NULL) {
4658     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4659     if (g1p->track_object_age(alloc_purpose)) {
4660       // We could simply do obj->incr_age(). However, this causes a
4661       // performance issue. obj->incr_age() will first check whether
4662       // the object has a displaced mark by checking its mark word;
4663       // getting the mark word from the new location of the object
4664       // stalls. So, given that we already have the mark word and we
4665       // are about to install it anyway, it's better to increase the
4666       // age on the mark word, when the object does not have a
4667       // displaced mark word. We're not expecting many objects to have
4668       // a displaced marked word, so that case is not optimized
4669       // further (it could be...) and we simply call obj->incr_age().
4670 
4671       if (m->has_displaced_mark_helper()) {
4672         // in this case, we have to install the mark word first,
4673         // otherwise obj looks to be forwarded (the old mark word,
4674         // which contains the forward pointer, was copied)
4675         obj->set_mark(m);
4676         obj->incr_age();
4677       } else {
4678         m = m->incr_age();
4679         obj->set_mark(m);
4680       }
4681       _par_scan_state->age_table()->add(obj, word_sz);
4682     } else {
4683       obj->set_mark(m);
4684     }
4685 
4686     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4687     surv_young_words[young_index] += word_sz;
4688 
4689     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4690       // We keep track of the next start index in the length field of
4691       // the to-space object. The actual length can be found in the
4692       // length field of the from-space object.
4693       arrayOop(obj)->set_length(0);
4694       oop* old_p = set_partial_array_mask(old);
4695       _par_scan_state->push_on_queue(old_p);
4696     } else {
4697       // No point in using the slower heap_region_containing() method,
4698       // given that we know obj is in the heap.
4699       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4700       obj->oop_iterate_backwards(&_scanner);
4701     }
4702   } else {
4703     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4704     obj = forward_ptr;
4705   }
4706   return obj;
4707 }
4708 
4709 template <class T>
4710 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4711   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4712     _scanned_klass->record_modified_oops();
4713   }
4714 }
4715 
4716 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4717 template <class T>
4718 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4719 ::do_oop_work(T* p) {
4720   oop obj = oopDesc::load_decode_heap_oop(p);
4721   assert(barrier != G1BarrierRS || obj != NULL,
4722          "Precondition: G1BarrierRS implies obj is non-NULL");
4723 
4724   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4725 
4726   // here the null check is implicit in the cset_fast_test() test
4727   if (_g1->in_cset_fast_test(obj)) {
4728     oop forwardee;
4729     if (obj->is_forwarded()) {
4730       forwardee = obj->forwardee();
4731     } else {
4732       forwardee = copy_to_survivor_space(obj);
4733     }
4734     assert(forwardee != NULL, "forwardee should not be NULL");
4735     oopDesc::encode_store_heap_oop(p, forwardee);
4736     if (do_mark_object && forwardee != obj) {
4737       // If the object is self-forwarded we don't need to explicitly
4738       // mark it, the evacuation failure protocol will do so.
4739       mark_forwarded_object(obj, forwardee);
4740     }
4741 
4742     // When scanning the RS, we only care about objs in CS.
4743     if (barrier == G1BarrierRS) {
4744       _par_scan_state->update_rs(_from, p, _worker_id);
4745     } else if (barrier == G1BarrierKlass) {
4746       do_klass_barrier(p, forwardee);
4747     }
4748   } else {
4749     // The object is not in collection set. If we're a root scanning
4750     // closure during an initial mark pause (i.e. do_mark_object will
4751     // be true) then attempt to mark the object.
4752     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4753       mark_object(obj);
4754     }
4755   }
4756 
4757   if (barrier == G1BarrierEvac && obj != NULL) {
4758     _par_scan_state->update_rs(_from, p, _worker_id);
4759   }
4760 
4761   if (do_gen_barrier && obj != NULL) {
4762     par_do_barrier(p);
4763   }
4764 }
4765 
4766 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4767 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4768 
4769 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4770   assert(has_partial_array_mask(p), "invariant");
4771   oop from_obj = clear_partial_array_mask(p);
4772 
4773   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4774   assert(from_obj->is_objArray(), "must be obj array");
4775   objArrayOop from_obj_array = objArrayOop(from_obj);
4776   // The from-space object contains the real length.
4777   int length                 = from_obj_array->length();
4778 
4779   assert(from_obj->is_forwarded(), "must be forwarded");
4780   oop to_obj                 = from_obj->forwardee();
4781   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4782   objArrayOop to_obj_array   = objArrayOop(to_obj);
4783   // We keep track of the next start index in the length field of the
4784   // to-space object.
4785   int next_index             = to_obj_array->length();
4786   assert(0 <= next_index && next_index < length,
4787          err_msg("invariant, next index: %d, length: %d", next_index, length));
4788 
4789   int start                  = next_index;
4790   int end                    = length;
4791   int remainder              = end - start;
4792   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4793   if (remainder > 2 * ParGCArrayScanChunk) {
4794     end = start + ParGCArrayScanChunk;
4795     to_obj_array->set_length(end);
4796     // Push the remainder before we process the range in case another
4797     // worker has run out of things to do and can steal it.
4798     oop* from_obj_p = set_partial_array_mask(from_obj);
4799     _par_scan_state->push_on_queue(from_obj_p);
4800   } else {
4801     assert(length == end, "sanity");
4802     // We'll process the final range for this object. Restore the length
4803     // so that the heap remains parsable in case of evacuation failure.
4804     to_obj_array->set_length(end);
4805   }
4806   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4807   // Process indexes [start,end). It will also process the header
4808   // along with the first chunk (i.e., the chunk with start == 0).
4809   // Note that at this point the length field of to_obj_array is not
4810   // correct given that we are using it to keep track of the next
4811   // start index. oop_iterate_range() (thankfully!) ignores the length
4812   // field and only relies on the start / end parameters.  It does
4813   // however return the size of the object which will be incorrect. So
4814   // we have to ignore it even if we wanted to use it.
4815   to_obj_array->oop_iterate_range(&_scanner, start, end);
4816 }
4817 
4818 class G1ParEvacuateFollowersClosure : public VoidClosure {
4819 protected:
4820   G1CollectedHeap*              _g1h;
4821   G1ParScanThreadState*         _par_scan_state;
4822   RefToScanQueueSet*            _queues;
4823   ParallelTaskTerminator*       _terminator;
4824 
4825   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4826   RefToScanQueueSet*      queues()         { return _queues; }
4827   ParallelTaskTerminator* terminator()     { return _terminator; }
4828 
4829 public:
4830   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4831                                 G1ParScanThreadState* par_scan_state,
4832                                 RefToScanQueueSet* queues,
4833                                 ParallelTaskTerminator* terminator)
4834     : _g1h(g1h), _par_scan_state(par_scan_state),
4835       _queues(queues), _terminator(terminator) {}
4836 
4837   void do_void();
4838 
4839 private:
4840   inline bool offer_termination();
4841 };
4842 
4843 bool G1ParEvacuateFollowersClosure::offer_termination() {
4844   G1ParScanThreadState* const pss = par_scan_state();
4845   pss->start_term_time();
4846   const bool res = terminator()->offer_termination();
4847   pss->end_term_time();
4848   return res;
4849 }
4850 
4851 void G1ParEvacuateFollowersClosure::do_void() {
4852   StarTask stolen_task;
4853   G1ParScanThreadState* const pss = par_scan_state();
4854   pss->trim_queue();
4855 
4856   do {
4857     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4858       assert(pss->verify_task(stolen_task), "sanity");
4859       if (stolen_task.is_narrow()) {
4860         pss->deal_with_reference((narrowOop*) stolen_task);
4861       } else {
4862         pss->deal_with_reference((oop*) stolen_task);
4863       }
4864 
4865       // We've just processed a reference and we might have made
4866       // available new entries on the queues. So we have to make sure
4867       // we drain the queues as necessary.
4868       pss->trim_queue();
4869     }
4870   } while (!offer_termination());
4871 
4872   pss->retire_alloc_buffers();
4873 }
4874 
4875 class G1KlassScanClosure : public KlassClosure {
4876  G1ParCopyHelper* _closure;
4877  bool             _process_only_dirty;
4878  int              _count;
4879  public:
4880   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4881       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4882   void do_klass(Klass* klass) {
4883     // If the klass has not been dirtied we know that there's
4884     // no references into  the young gen and we can skip it.
4885    if (!_process_only_dirty || klass->has_modified_oops()) {
4886       // Clean the klass since we're going to scavenge all the metadata.
4887       klass->clear_modified_oops();
4888 
4889       // Tell the closure that this klass is the Klass to scavenge
4890       // and is the one to dirty if oops are left pointing into the young gen.
4891       _closure->set_scanned_klass(klass);
4892 
4893       klass->oops_do(_closure);
4894 
4895       _closure->set_scanned_klass(NULL);
4896     }
4897     _count++;
4898   }
4899 };
4900 
4901 class G1ParTask : public AbstractGangTask {
4902 protected:
4903   G1CollectedHeap*       _g1h;
4904   RefToScanQueueSet      *_queues;
4905   ParallelTaskTerminator _terminator;
4906   uint _n_workers;
4907 
4908   Mutex _stats_lock;
4909   Mutex* stats_lock() { return &_stats_lock; }
4910 
4911   size_t getNCards() {
4912     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4913       / G1BlockOffsetSharedArray::N_bytes;
4914   }
4915 
4916 public:
4917   G1ParTask(G1CollectedHeap* g1h,
4918             RefToScanQueueSet *task_queues)
4919     : AbstractGangTask("G1 collection"),
4920       _g1h(g1h),
4921       _queues(task_queues),
4922       _terminator(0, _queues),
4923       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4924   {}
4925 
4926   RefToScanQueueSet* queues() { return _queues; }
4927 
4928   RefToScanQueue *work_queue(int i) {
4929     return queues()->queue(i);
4930   }
4931 
4932   ParallelTaskTerminator* terminator() { return &_terminator; }
4933 
4934   virtual void set_for_termination(int active_workers) {
4935     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4936     // in the young space (_par_seq_tasks) in the G1 heap
4937     // for SequentialSubTasksDone.
4938     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4939     // both of which need setting by set_n_termination().
4940     _g1h->SharedHeap::set_n_termination(active_workers);
4941     _g1h->set_n_termination(active_workers);
4942     terminator()->reset_for_reuse(active_workers);
4943     _n_workers = active_workers;
4944   }
4945 
4946   void work(uint worker_id) {
4947     if (worker_id >= _n_workers) return;  // no work needed this round
4948 
4949     double start_time_ms = os::elapsedTime() * 1000.0;
4950     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4951 
4952     {
4953       ResourceMark rm;
4954       HandleMark   hm;
4955 
4956       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4957 
4958       G1ParScanThreadState            pss(_g1h, worker_id);
4959       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
4960       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4961       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
4962 
4963       pss.set_evac_closure(&scan_evac_cl);
4964       pss.set_evac_failure_closure(&evac_failure_cl);
4965       pss.set_partial_scan_closure(&partial_scan_cl);
4966 
4967       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4968       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
4969 
4970       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4971       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4972 
4973       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
4974       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4975       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4976 
4977       OopClosure*                    scan_root_cl = &only_scan_root_cl;
4978       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
4979 
4980       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4981         // We also need to mark copied objects.
4982         scan_root_cl = &scan_mark_root_cl;
4983         scan_klasses_cl = &scan_mark_klasses_cl_s;
4984       }
4985 
4986       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
4987 
4988       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
4989 
4990       pss.start_strong_roots();
4991       _g1h->g1_process_strong_roots(/* is scavenging */ true,
4992                                     SharedHeap::ScanningOption(so),
4993                                     scan_root_cl,
4994                                     &push_heap_rs_cl,
4995                                     scan_klasses_cl,
4996                                     worker_id);
4997       pss.end_strong_roots();
4998 
4999       {
5000         double start = os::elapsedTime();
5001         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5002         evac.do_void();
5003         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5004         double term_ms = pss.term_time()*1000.0;
5005         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5006         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5007       }
5008       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5009       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5010 
5011       if (ParallelGCVerbose) {
5012         MutexLocker x(stats_lock());
5013         pss.print_termination_stats(worker_id);
5014       }
5015 
5016       assert(pss.refs()->is_empty(), "should be empty");
5017 
5018       // Close the inner scope so that the ResourceMark and HandleMark
5019       // destructors are executed here and are included as part of the
5020       // "GC Worker Time".
5021     }
5022 
5023     double end_time_ms = os::elapsedTime() * 1000.0;
5024     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5025   }
5026 };
5027 
5028 // *** Common G1 Evacuation Stuff
5029 
5030 // Closures that support the filtering of CodeBlobs scanned during
5031 // external root scanning.
5032 
5033 // Closure applied to reference fields in code blobs (specifically nmethods)
5034 // to determine whether an nmethod contains references that point into
5035 // the collection set. Used as a predicate when walking code roots so
5036 // that only nmethods that point into the collection set are added to the
5037 // 'marked' list.
5038 
5039 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
5040 
5041   class G1PointsIntoCSOopClosure : public OopClosure {
5042     G1CollectedHeap* _g1;
5043     bool _points_into_cs;
5044   public:
5045     G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
5046       _g1(g1), _points_into_cs(false) { }
5047 
5048     bool points_into_cs() const { return _points_into_cs; }
5049 
5050     template <class T>
5051     void do_oop_nv(T* p) {
5052       if (!_points_into_cs) {
5053         T heap_oop = oopDesc::load_heap_oop(p);
5054         if (!oopDesc::is_null(heap_oop) &&
5055             _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
5056           _points_into_cs = true;
5057         }
5058       }
5059     }
5060 
5061     virtual void do_oop(oop* p)        { do_oop_nv(p); }
5062     virtual void do_oop(narrowOop* p)  { do_oop_nv(p); }
5063   };
5064 
5065   G1CollectedHeap* _g1;
5066 
5067 public:
5068   G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
5069     CodeBlobToOopClosure(cl, true), _g1(g1) { }
5070 
5071   virtual void do_code_blob(CodeBlob* cb) {
5072     nmethod* nm = cb->as_nmethod_or_null();
5073     if (nm != NULL && !(nm->test_oops_do_mark())) {
5074       G1PointsIntoCSOopClosure predicate_cl(_g1);
5075       nm->oops_do(&predicate_cl);
5076 
5077       if (predicate_cl.points_into_cs()) {
5078         // At least one of the reference fields or the oop relocations
5079         // in the nmethod points into the collection set. We have to
5080         // 'mark' this nmethod.
5081         // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
5082         // or MarkingCodeBlobClosure::do_code_blob() change.
5083         if (!nm->test_set_oops_do_mark()) {
5084           do_newly_marked_nmethod(nm);
5085         }
5086       }
5087     }
5088   }
5089 };
5090 
5091 // This method is run in a GC worker.
5092 
5093 void
5094 G1CollectedHeap::
5095 g1_process_strong_roots(bool is_scavenging,
5096                         ScanningOption so,
5097                         OopClosure* scan_non_heap_roots,
5098                         OopsInHeapRegionClosure* scan_rs,
5099                         G1KlassScanClosure* scan_klasses,
5100                         int worker_i) {
5101 
5102   // First scan the strong roots
5103   double ext_roots_start = os::elapsedTime();
5104   double closure_app_time_sec = 0.0;
5105 
5106   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5107 
5108   // Walk the code cache w/o buffering, because StarTask cannot handle
5109   // unaligned oop locations.
5110   G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5111 
5112   process_strong_roots(false, // no scoping; this is parallel code
5113                        is_scavenging, so,
5114                        &buf_scan_non_heap_roots,
5115                        &eager_scan_code_roots,
5116                        scan_klasses
5117                        );
5118 
5119   // Now the CM ref_processor roots.
5120   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5121     // We need to treat the discovered reference lists of the
5122     // concurrent mark ref processor as roots and keep entries
5123     // (which are added by the marking threads) on them live
5124     // until they can be processed at the end of marking.
5125     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5126   }
5127 
5128   // Finish up any enqueued closure apps (attributed as object copy time).
5129   buf_scan_non_heap_roots.done();
5130 
5131   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5132 
5133   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5134 
5135   double ext_root_time_ms =
5136     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5137 
5138   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5139 
5140   // During conc marking we have to filter the per-thread SATB buffers
5141   // to make sure we remove any oops into the CSet (which will show up
5142   // as implicitly live).
5143   double satb_filtering_ms = 0.0;
5144   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5145     if (mark_in_progress()) {
5146       double satb_filter_start = os::elapsedTime();
5147 
5148       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5149 
5150       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5151     }
5152   }
5153   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5154 
5155   // Now scan the complement of the collection set.
5156   if (scan_rs != NULL) {
5157     g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5158   }
5159   _process_strong_tasks->all_tasks_completed();
5160 }
5161 
5162 void
5163 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5164   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5165   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5166 }
5167 
5168 // Weak Reference Processing support
5169 
5170 // An always "is_alive" closure that is used to preserve referents.
5171 // If the object is non-null then it's alive.  Used in the preservation
5172 // of referent objects that are pointed to by reference objects
5173 // discovered by the CM ref processor.
5174 class G1AlwaysAliveClosure: public BoolObjectClosure {
5175   G1CollectedHeap* _g1;
5176 public:
5177   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5178   bool do_object_b(oop p) {
5179     if (p != NULL) {
5180       return true;
5181     }
5182     return false;
5183   }
5184 };
5185 
5186 bool G1STWIsAliveClosure::do_object_b(oop p) {
5187   // An object is reachable if it is outside the collection set,
5188   // or is inside and copied.
5189   return !_g1->obj_in_cs(p) || p->is_forwarded();
5190 }
5191 
5192 // Non Copying Keep Alive closure
5193 class G1KeepAliveClosure: public OopClosure {
5194   G1CollectedHeap* _g1;
5195 public:
5196   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5197   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5198   void do_oop(      oop* p) {
5199     oop obj = *p;
5200 
5201     if (_g1->obj_in_cs(obj)) {
5202       assert( obj->is_forwarded(), "invariant" );
5203       *p = obj->forwardee();
5204     }
5205   }
5206 };
5207 
5208 // Copying Keep Alive closure - can be called from both
5209 // serial and parallel code as long as different worker
5210 // threads utilize different G1ParScanThreadState instances
5211 // and different queues.
5212 
5213 class G1CopyingKeepAliveClosure: public OopClosure {
5214   G1CollectedHeap*         _g1h;
5215   OopClosure*              _copy_non_heap_obj_cl;
5216   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5217   G1ParScanThreadState*    _par_scan_state;
5218 
5219 public:
5220   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5221                             OopClosure* non_heap_obj_cl,
5222                             OopsInHeapRegionClosure* metadata_obj_cl,
5223                             G1ParScanThreadState* pss):
5224     _g1h(g1h),
5225     _copy_non_heap_obj_cl(non_heap_obj_cl),
5226     _copy_metadata_obj_cl(metadata_obj_cl),
5227     _par_scan_state(pss)
5228   {}
5229 
5230   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5231   virtual void do_oop(      oop* p) { do_oop_work(p); }
5232 
5233   template <class T> void do_oop_work(T* p) {
5234     oop obj = oopDesc::load_decode_heap_oop(p);
5235 
5236     if (_g1h->obj_in_cs(obj)) {
5237       // If the referent object has been forwarded (either copied
5238       // to a new location or to itself in the event of an
5239       // evacuation failure) then we need to update the reference
5240       // field and, if both reference and referent are in the G1
5241       // heap, update the RSet for the referent.
5242       //
5243       // If the referent has not been forwarded then we have to keep
5244       // it alive by policy. Therefore we have copy the referent.
5245       //
5246       // If the reference field is in the G1 heap then we can push
5247       // on the PSS queue. When the queue is drained (after each
5248       // phase of reference processing) the object and it's followers
5249       // will be copied, the reference field set to point to the
5250       // new location, and the RSet updated. Otherwise we need to
5251       // use the the non-heap or metadata closures directly to copy
5252       // the referent object and update the pointer, while avoiding
5253       // updating the RSet.
5254 
5255       if (_g1h->is_in_g1_reserved(p)) {
5256         _par_scan_state->push_on_queue(p);
5257       } else {
5258         assert(!ClassLoaderDataGraph::contains((address)p),
5259                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5260                               PTR_FORMAT, p));
5261           _copy_non_heap_obj_cl->do_oop(p);
5262         }
5263       }
5264     }
5265 };
5266 
5267 // Serial drain queue closure. Called as the 'complete_gc'
5268 // closure for each discovered list in some of the
5269 // reference processing phases.
5270 
5271 class G1STWDrainQueueClosure: public VoidClosure {
5272 protected:
5273   G1CollectedHeap* _g1h;
5274   G1ParScanThreadState* _par_scan_state;
5275 
5276   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5277 
5278 public:
5279   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5280     _g1h(g1h),
5281     _par_scan_state(pss)
5282   { }
5283 
5284   void do_void() {
5285     G1ParScanThreadState* const pss = par_scan_state();
5286     pss->trim_queue();
5287   }
5288 };
5289 
5290 // Parallel Reference Processing closures
5291 
5292 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5293 // processing during G1 evacuation pauses.
5294 
5295 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5296 private:
5297   G1CollectedHeap*   _g1h;
5298   RefToScanQueueSet* _queues;
5299   FlexibleWorkGang*  _workers;
5300   int                _active_workers;
5301 
5302 public:
5303   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5304                         FlexibleWorkGang* workers,
5305                         RefToScanQueueSet *task_queues,
5306                         int n_workers) :
5307     _g1h(g1h),
5308     _queues(task_queues),
5309     _workers(workers),
5310     _active_workers(n_workers)
5311   {
5312     assert(n_workers > 0, "shouldn't call this otherwise");
5313   }
5314 
5315   // Executes the given task using concurrent marking worker threads.
5316   virtual void execute(ProcessTask& task);
5317   virtual void execute(EnqueueTask& task);
5318 };
5319 
5320 // Gang task for possibly parallel reference processing
5321 
5322 class G1STWRefProcTaskProxy: public AbstractGangTask {
5323   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5324   ProcessTask&     _proc_task;
5325   G1CollectedHeap* _g1h;
5326   RefToScanQueueSet *_task_queues;
5327   ParallelTaskTerminator* _terminator;
5328 
5329 public:
5330   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5331                      G1CollectedHeap* g1h,
5332                      RefToScanQueueSet *task_queues,
5333                      ParallelTaskTerminator* terminator) :
5334     AbstractGangTask("Process reference objects in parallel"),
5335     _proc_task(proc_task),
5336     _g1h(g1h),
5337     _task_queues(task_queues),
5338     _terminator(terminator)
5339   {}
5340 
5341   virtual void work(uint worker_id) {
5342     // The reference processing task executed by a single worker.
5343     ResourceMark rm;
5344     HandleMark   hm;
5345 
5346     G1STWIsAliveClosure is_alive(_g1h);
5347 
5348     G1ParScanThreadState pss(_g1h, worker_id);
5349 
5350     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5351     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5352     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5353 
5354     pss.set_evac_closure(&scan_evac_cl);
5355     pss.set_evac_failure_closure(&evac_failure_cl);
5356     pss.set_partial_scan_closure(&partial_scan_cl);
5357 
5358     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5359     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5360 
5361     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5362     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5363 
5364     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5365     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5366 
5367     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5368       // We also need to mark copied objects.
5369       copy_non_heap_cl = &copy_mark_non_heap_cl;
5370       copy_metadata_cl = &copy_mark_metadata_cl;
5371     }
5372 
5373     // Keep alive closure.
5374     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5375 
5376     // Complete GC closure
5377     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5378 
5379     // Call the reference processing task's work routine.
5380     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5381 
5382     // Note we cannot assert that the refs array is empty here as not all
5383     // of the processing tasks (specifically phase2 - pp2_work) execute
5384     // the complete_gc closure (which ordinarily would drain the queue) so
5385     // the queue may not be empty.
5386   }
5387 };
5388 
5389 // Driver routine for parallel reference processing.
5390 // Creates an instance of the ref processing gang
5391 // task and has the worker threads execute it.
5392 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5393   assert(_workers != NULL, "Need parallel worker threads.");
5394 
5395   ParallelTaskTerminator terminator(_active_workers, _queues);
5396   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5397 
5398   _g1h->set_par_threads(_active_workers);
5399   _workers->run_task(&proc_task_proxy);
5400   _g1h->set_par_threads(0);
5401 }
5402 
5403 // Gang task for parallel reference enqueueing.
5404 
5405 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5406   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5407   EnqueueTask& _enq_task;
5408 
5409 public:
5410   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5411     AbstractGangTask("Enqueue reference objects in parallel"),
5412     _enq_task(enq_task)
5413   { }
5414 
5415   virtual void work(uint worker_id) {
5416     _enq_task.work(worker_id);
5417   }
5418 };
5419 
5420 // Driver routine for parallel reference enqueueing.
5421 // Creates an instance of the ref enqueueing gang
5422 // task and has the worker threads execute it.
5423 
5424 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5425   assert(_workers != NULL, "Need parallel worker threads.");
5426 
5427   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5428 
5429   _g1h->set_par_threads(_active_workers);
5430   _workers->run_task(&enq_task_proxy);
5431   _g1h->set_par_threads(0);
5432 }
5433 
5434 // End of weak reference support closures
5435 
5436 // Abstract task used to preserve (i.e. copy) any referent objects
5437 // that are in the collection set and are pointed to by reference
5438 // objects discovered by the CM ref processor.
5439 
5440 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5441 protected:
5442   G1CollectedHeap* _g1h;
5443   RefToScanQueueSet      *_queues;
5444   ParallelTaskTerminator _terminator;
5445   uint _n_workers;
5446 
5447 public:
5448   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5449     AbstractGangTask("ParPreserveCMReferents"),
5450     _g1h(g1h),
5451     _queues(task_queues),
5452     _terminator(workers, _queues),
5453     _n_workers(workers)
5454   { }
5455 
5456   void work(uint worker_id) {
5457     ResourceMark rm;
5458     HandleMark   hm;
5459 
5460     G1ParScanThreadState            pss(_g1h, worker_id);
5461     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5462     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5463     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5464 
5465     pss.set_evac_closure(&scan_evac_cl);
5466     pss.set_evac_failure_closure(&evac_failure_cl);
5467     pss.set_partial_scan_closure(&partial_scan_cl);
5468 
5469     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5470 
5471 
5472     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5473     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5474 
5475     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5476     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5477 
5478     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5479     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5480 
5481     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5482       // We also need to mark copied objects.
5483       copy_non_heap_cl = &copy_mark_non_heap_cl;
5484       copy_metadata_cl = &copy_mark_metadata_cl;
5485     }
5486 
5487     // Is alive closure
5488     G1AlwaysAliveClosure always_alive(_g1h);
5489 
5490     // Copying keep alive closure. Applied to referent objects that need
5491     // to be copied.
5492     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5493 
5494     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5495 
5496     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5497     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5498 
5499     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5500     // So this must be true - but assert just in case someone decides to
5501     // change the worker ids.
5502     assert(0 <= worker_id && worker_id < limit, "sanity");
5503     assert(!rp->discovery_is_atomic(), "check this code");
5504 
5505     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5506     for (uint idx = worker_id; idx < limit; idx += stride) {
5507       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5508 
5509       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5510       while (iter.has_next()) {
5511         // Since discovery is not atomic for the CM ref processor, we
5512         // can see some null referent objects.
5513         iter.load_ptrs(DEBUG_ONLY(true));
5514         oop ref = iter.obj();
5515 
5516         // This will filter nulls.
5517         if (iter.is_referent_alive()) {
5518           iter.make_referent_alive();
5519         }
5520         iter.move_to_next();
5521       }
5522     }
5523 
5524     // Drain the queue - which may cause stealing
5525     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5526     drain_queue.do_void();
5527     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5528     assert(pss.refs()->is_empty(), "should be");
5529   }
5530 };
5531 
5532 // Weak Reference processing during an evacuation pause (part 1).
5533 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5534   double ref_proc_start = os::elapsedTime();
5535 
5536   ReferenceProcessor* rp = _ref_processor_stw;
5537   assert(rp->discovery_enabled(), "should have been enabled");
5538 
5539   // Any reference objects, in the collection set, that were 'discovered'
5540   // by the CM ref processor should have already been copied (either by
5541   // applying the external root copy closure to the discovered lists, or
5542   // by following an RSet entry).
5543   //
5544   // But some of the referents, that are in the collection set, that these
5545   // reference objects point to may not have been copied: the STW ref
5546   // processor would have seen that the reference object had already
5547   // been 'discovered' and would have skipped discovering the reference,
5548   // but would not have treated the reference object as a regular oop.
5549   // As a result the copy closure would not have been applied to the
5550   // referent object.
5551   //
5552   // We need to explicitly copy these referent objects - the references
5553   // will be processed at the end of remarking.
5554   //
5555   // We also need to do this copying before we process the reference
5556   // objects discovered by the STW ref processor in case one of these
5557   // referents points to another object which is also referenced by an
5558   // object discovered by the STW ref processor.
5559 
5560   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5561            no_of_gc_workers == workers()->active_workers(),
5562            "Need to reset active GC workers");
5563 
5564   set_par_threads(no_of_gc_workers);
5565   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5566                                                  no_of_gc_workers,
5567                                                  _task_queues);
5568 
5569   if (G1CollectedHeap::use_parallel_gc_threads()) {
5570     workers()->run_task(&keep_cm_referents);
5571   } else {
5572     keep_cm_referents.work(0);
5573   }
5574 
5575   set_par_threads(0);
5576 
5577   // Closure to test whether a referent is alive.
5578   G1STWIsAliveClosure is_alive(this);
5579 
5580   // Even when parallel reference processing is enabled, the processing
5581   // of JNI refs is serial and performed serially by the current thread
5582   // rather than by a worker. The following PSS will be used for processing
5583   // JNI refs.
5584 
5585   // Use only a single queue for this PSS.
5586   G1ParScanThreadState pss(this, 0);
5587 
5588   // We do not embed a reference processor in the copying/scanning
5589   // closures while we're actually processing the discovered
5590   // reference objects.
5591   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5592   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5593   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5594 
5595   pss.set_evac_closure(&scan_evac_cl);
5596   pss.set_evac_failure_closure(&evac_failure_cl);
5597   pss.set_partial_scan_closure(&partial_scan_cl);
5598 
5599   assert(pss.refs()->is_empty(), "pre-condition");
5600 
5601   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5602   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5603 
5604   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5605   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5606 
5607   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5608   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5609 
5610   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5611     // We also need to mark copied objects.
5612     copy_non_heap_cl = &copy_mark_non_heap_cl;
5613     copy_metadata_cl = &copy_mark_metadata_cl;
5614   }
5615 
5616   // Keep alive closure.
5617   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5618 
5619   // Serial Complete GC closure
5620   G1STWDrainQueueClosure drain_queue(this, &pss);
5621 
5622   // Setup the soft refs policy...
5623   rp->setup_policy(false);
5624 
5625   ReferenceProcessorStats stats;
5626   if (!rp->processing_is_mt()) {
5627     // Serial reference processing...
5628     stats = rp->process_discovered_references(&is_alive,
5629                                               &keep_alive,
5630                                               &drain_queue,
5631                                               NULL,
5632                                               _gc_timer_stw);
5633   } else {
5634     // Parallel reference processing
5635     assert(rp->num_q() == no_of_gc_workers, "sanity");
5636     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5637 
5638     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5639     stats = rp->process_discovered_references(&is_alive,
5640                                               &keep_alive,
5641                                               &drain_queue,
5642                                               &par_task_executor,
5643                                               _gc_timer_stw);
5644   }
5645 
5646   _gc_tracer_stw->report_gc_reference_stats(stats);
5647   // We have completed copying any necessary live referent objects
5648   // (that were not copied during the actual pause) so we can
5649   // retire any active alloc buffers
5650   pss.retire_alloc_buffers();
5651   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5652 
5653   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5654   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5655 }
5656 
5657 // Weak Reference processing during an evacuation pause (part 2).
5658 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5659   double ref_enq_start = os::elapsedTime();
5660 
5661   ReferenceProcessor* rp = _ref_processor_stw;
5662   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5663 
5664   // Now enqueue any remaining on the discovered lists on to
5665   // the pending list.
5666   if (!rp->processing_is_mt()) {
5667     // Serial reference processing...
5668     rp->enqueue_discovered_references();
5669   } else {
5670     // Parallel reference enqueueing
5671 
5672     assert(no_of_gc_workers == workers()->active_workers(),
5673            "Need to reset active workers");
5674     assert(rp->num_q() == no_of_gc_workers, "sanity");
5675     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5676 
5677     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5678     rp->enqueue_discovered_references(&par_task_executor);
5679   }
5680 
5681   rp->verify_no_references_recorded();
5682   assert(!rp->discovery_enabled(), "should have been disabled");
5683 
5684   // FIXME
5685   // CM's reference processing also cleans up the string and symbol tables.
5686   // Should we do that here also? We could, but it is a serial operation
5687   // and could significantly increase the pause time.
5688 
5689   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5690   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5691 }
5692 
5693 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5694   _expand_heap_after_alloc_failure = true;
5695   _evacuation_failed = false;
5696 
5697   // Should G1EvacuationFailureALot be in effect for this GC?
5698   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5699 
5700   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5701 
5702   // Disable the hot card cache.
5703   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5704   hot_card_cache->reset_hot_cache_claimed_index();
5705   hot_card_cache->set_use_cache(false);
5706 
5707   uint n_workers;
5708   if (G1CollectedHeap::use_parallel_gc_threads()) {
5709     n_workers =
5710       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5711                                      workers()->active_workers(),
5712                                      Threads::number_of_non_daemon_threads());
5713     assert(UseDynamicNumberOfGCThreads ||
5714            n_workers == workers()->total_workers(),
5715            "If not dynamic should be using all the  workers");
5716     workers()->set_active_workers(n_workers);
5717     set_par_threads(n_workers);
5718   } else {
5719     assert(n_par_threads() == 0,
5720            "Should be the original non-parallel value");
5721     n_workers = 1;
5722   }
5723 
5724   G1ParTask g1_par_task(this, _task_queues);
5725 
5726   init_for_evac_failure(NULL);
5727 
5728   rem_set()->prepare_for_younger_refs_iterate(true);
5729 
5730   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5731   double start_par_time_sec = os::elapsedTime();
5732   double end_par_time_sec;
5733 
5734   {
5735     StrongRootsScope srs(this);
5736 
5737     if (G1CollectedHeap::use_parallel_gc_threads()) {
5738       // The individual threads will set their evac-failure closures.
5739       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5740       // These tasks use ShareHeap::_process_strong_tasks
5741       assert(UseDynamicNumberOfGCThreads ||
5742              workers()->active_workers() == workers()->total_workers(),
5743              "If not dynamic should be using all the  workers");
5744       workers()->run_task(&g1_par_task);
5745     } else {
5746       g1_par_task.set_for_termination(n_workers);
5747       g1_par_task.work(0);
5748     }
5749     end_par_time_sec = os::elapsedTime();
5750 
5751     // Closing the inner scope will execute the destructor
5752     // for the StrongRootsScope object. We record the current
5753     // elapsed time before closing the scope so that time
5754     // taken for the SRS destructor is NOT included in the
5755     // reported parallel time.
5756   }
5757 
5758   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5759   g1_policy()->phase_times()->record_par_time(par_time_ms);
5760 
5761   double code_root_fixup_time_ms =
5762         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5763   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5764 
5765   set_par_threads(0);
5766 
5767   // Process any discovered reference objects - we have
5768   // to do this _before_ we retire the GC alloc regions
5769   // as we may have to copy some 'reachable' referent
5770   // objects (and their reachable sub-graphs) that were
5771   // not copied during the pause.
5772   process_discovered_references(n_workers);
5773 
5774   // Weak root processing.
5775   // Note: when JSR 292 is enabled and code blobs can contain
5776   // non-perm oops then we will need to process the code blobs
5777   // here too.
5778   {
5779     G1STWIsAliveClosure is_alive(this);
5780     G1KeepAliveClosure keep_alive(this);
5781     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5782   }
5783 
5784   release_gc_alloc_regions(n_workers, evacuation_info);
5785   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5786 
5787   // Reset and re-enable the hot card cache.
5788   // Note the counts for the cards in the regions in the
5789   // collection set are reset when the collection set is freed.
5790   hot_card_cache->reset_hot_cache();
5791   hot_card_cache->set_use_cache(true);
5792 
5793   finalize_for_evac_failure();
5794 
5795   if (evacuation_failed()) {
5796     remove_self_forwarding_pointers();
5797 
5798     // Reset the G1EvacuationFailureALot counters and flags
5799     // Note: the values are reset only when an actual
5800     // evacuation failure occurs.
5801     NOT_PRODUCT(reset_evacuation_should_fail();)
5802   }
5803 
5804   // Enqueue any remaining references remaining on the STW
5805   // reference processor's discovered lists. We need to do
5806   // this after the card table is cleaned (and verified) as
5807   // the act of enqueueing entries on to the pending list
5808   // will log these updates (and dirty their associated
5809   // cards). We need these updates logged to update any
5810   // RSets.
5811   enqueue_discovered_references(n_workers);
5812 
5813   if (G1DeferredRSUpdate) {
5814     RedirtyLoggedCardTableEntryFastClosure redirty;
5815     dirty_card_queue_set().set_closure(&redirty);
5816     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5817 
5818     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5819     dcq.merge_bufferlists(&dirty_card_queue_set());
5820     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5821   }
5822   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5823 }
5824 
5825 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5826                                      size_t* pre_used,
5827                                      FreeRegionList* free_list,
5828                                      OldRegionSet* old_proxy_set,
5829                                      HumongousRegionSet* humongous_proxy_set,
5830                                      HRRSCleanupTask* hrrs_cleanup_task,
5831                                      bool par) {
5832   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5833     if (hr->isHumongous()) {
5834       assert(hr->startsHumongous(), "we should only see starts humongous");
5835       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5836     } else {
5837       _old_set.remove_with_proxy(hr, old_proxy_set);
5838       free_region(hr, pre_used, free_list, par);
5839     }
5840   } else {
5841     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5842   }
5843 }
5844 
5845 void G1CollectedHeap::free_region(HeapRegion* hr,
5846                                   size_t* pre_used,
5847                                   FreeRegionList* free_list,
5848                                   bool par) {
5849   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5850   assert(!hr->is_empty(), "the region should not be empty");
5851   assert(free_list != NULL, "pre-condition");
5852 
5853   // Clear the card counts for this region.
5854   // Note: we only need to do this if the region is not young
5855   // (since we don't refine cards in young regions).
5856   if (!hr->is_young()) {
5857     _cg1r->hot_card_cache()->reset_card_counts(hr);
5858   }
5859   *pre_used += hr->used();
5860   hr->hr_clear(par, true /* clear_space */);
5861   free_list->add_as_head(hr);
5862 }
5863 
5864 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5865                                      size_t* pre_used,
5866                                      FreeRegionList* free_list,
5867                                      HumongousRegionSet* humongous_proxy_set,
5868                                      bool par) {
5869   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5870   assert(free_list != NULL, "pre-condition");
5871   assert(humongous_proxy_set != NULL, "pre-condition");
5872 
5873   size_t hr_used = hr->used();
5874   size_t hr_capacity = hr->capacity();
5875   size_t hr_pre_used = 0;
5876   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5877   // We need to read this before we make the region non-humongous,
5878   // otherwise the information will be gone.
5879   uint last_index = hr->last_hc_index();
5880   hr->set_notHumongous();
5881   free_region(hr, &hr_pre_used, free_list, par);
5882 
5883   uint i = hr->hrs_index() + 1;
5884   while (i < last_index) {
5885     HeapRegion* curr_hr = region_at(i);
5886     assert(curr_hr->continuesHumongous(), "invariant");
5887     curr_hr->set_notHumongous();
5888     free_region(curr_hr, &hr_pre_used, free_list, par);
5889     i += 1;
5890   }
5891   assert(hr_pre_used == hr_used,
5892          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5893                  "should be the same", hr_pre_used, hr_used));
5894   *pre_used += hr_pre_used;
5895 }
5896 
5897 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5898                                        FreeRegionList* free_list,
5899                                        OldRegionSet* old_proxy_set,
5900                                        HumongousRegionSet* humongous_proxy_set,
5901                                        bool par) {
5902   if (pre_used > 0) {
5903     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5904     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5905     assert(_summary_bytes_used >= pre_used,
5906            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5907                    "should be >= pre_used: "SIZE_FORMAT,
5908                    _summary_bytes_used, pre_used));
5909     _summary_bytes_used -= pre_used;
5910   }
5911   if (free_list != NULL && !free_list->is_empty()) {
5912     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5913     _free_list.add_as_head(free_list);
5914   }
5915   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5916     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5917     _old_set.update_from_proxy(old_proxy_set);
5918   }
5919   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5920     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5921     _humongous_set.update_from_proxy(humongous_proxy_set);
5922   }
5923 }
5924 
5925 class G1ParCleanupCTTask : public AbstractGangTask {
5926   CardTableModRefBS* _ct_bs;
5927   G1CollectedHeap* _g1h;
5928   HeapRegion* volatile _su_head;
5929 public:
5930   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5931                      G1CollectedHeap* g1h) :
5932     AbstractGangTask("G1 Par Cleanup CT Task"),
5933     _ct_bs(ct_bs), _g1h(g1h) { }
5934 
5935   void work(uint worker_id) {
5936     HeapRegion* r;
5937     while (r = _g1h->pop_dirty_cards_region()) {
5938       clear_cards(r);
5939     }
5940   }
5941 
5942   void clear_cards(HeapRegion* r) {
5943     // Cards of the survivors should have already been dirtied.
5944     if (!r->is_survivor()) {
5945       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5946     }
5947   }
5948 };
5949 
5950 #ifndef PRODUCT
5951 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5952   G1CollectedHeap* _g1h;
5953   CardTableModRefBS* _ct_bs;
5954 public:
5955   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5956     : _g1h(g1h), _ct_bs(ct_bs) { }
5957   virtual bool doHeapRegion(HeapRegion* r) {
5958     if (r->is_survivor()) {
5959       _g1h->verify_dirty_region(r);
5960     } else {
5961       _g1h->verify_not_dirty_region(r);
5962     }
5963     return false;
5964   }
5965 };
5966 
5967 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5968   // All of the region should be clean.
5969   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5970   MemRegion mr(hr->bottom(), hr->end());
5971   ct_bs->verify_not_dirty_region(mr);
5972 }
5973 
5974 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5975   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5976   // dirty allocated blocks as they allocate them. The thread that
5977   // retires each region and replaces it with a new one will do a
5978   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5979   // not dirty that area (one less thing to have to do while holding
5980   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5981   // is dirty.
5982   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5983   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5984   ct_bs->verify_dirty_region(mr);
5985 }
5986 
5987 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5988   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5989   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5990     verify_dirty_region(hr);
5991   }
5992 }
5993 
5994 void G1CollectedHeap::verify_dirty_young_regions() {
5995   verify_dirty_young_list(_young_list->first_region());
5996 }
5997 #endif
5998 
5999 void G1CollectedHeap::cleanUpCardTable() {
6000   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
6001   double start = os::elapsedTime();
6002 
6003   {
6004     // Iterate over the dirty cards region list.
6005     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6006 
6007     if (G1CollectedHeap::use_parallel_gc_threads()) {
6008       set_par_threads();
6009       workers()->run_task(&cleanup_task);
6010       set_par_threads(0);
6011     } else {
6012       while (_dirty_cards_region_list) {
6013         HeapRegion* r = _dirty_cards_region_list;
6014         cleanup_task.clear_cards(r);
6015         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6016         if (_dirty_cards_region_list == r) {
6017           // The last region.
6018           _dirty_cards_region_list = NULL;
6019         }
6020         r->set_next_dirty_cards_region(NULL);
6021       }
6022     }
6023 #ifndef PRODUCT
6024     if (G1VerifyCTCleanup || VerifyAfterGC) {
6025       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6026       heap_region_iterate(&cleanup_verifier);
6027     }
6028 #endif
6029   }
6030 
6031   double elapsed = os::elapsedTime() - start;
6032   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6033 }
6034 
6035 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6036   size_t pre_used = 0;
6037   FreeRegionList local_free_list("Local List for CSet Freeing");
6038 
6039   double young_time_ms     = 0.0;
6040   double non_young_time_ms = 0.0;
6041 
6042   // Since the collection set is a superset of the the young list,
6043   // all we need to do to clear the young list is clear its
6044   // head and length, and unlink any young regions in the code below
6045   _young_list->clear();
6046 
6047   G1CollectorPolicy* policy = g1_policy();
6048 
6049   double start_sec = os::elapsedTime();
6050   bool non_young = true;
6051 
6052   HeapRegion* cur = cs_head;
6053   int age_bound = -1;
6054   size_t rs_lengths = 0;
6055 
6056   while (cur != NULL) {
6057     assert(!is_on_master_free_list(cur), "sanity");
6058     if (non_young) {
6059       if (cur->is_young()) {
6060         double end_sec = os::elapsedTime();
6061         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6062         non_young_time_ms += elapsed_ms;
6063 
6064         start_sec = os::elapsedTime();
6065         non_young = false;
6066       }
6067     } else {
6068       if (!cur->is_young()) {
6069         double end_sec = os::elapsedTime();
6070         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6071         young_time_ms += elapsed_ms;
6072 
6073         start_sec = os::elapsedTime();
6074         non_young = true;
6075       }
6076     }
6077 
6078     rs_lengths += cur->rem_set()->occupied();
6079 
6080     HeapRegion* next = cur->next_in_collection_set();
6081     assert(cur->in_collection_set(), "bad CS");
6082     cur->set_next_in_collection_set(NULL);
6083     cur->set_in_collection_set(false);
6084 
6085     if (cur->is_young()) {
6086       int index = cur->young_index_in_cset();
6087       assert(index != -1, "invariant");
6088       assert((uint) index < policy->young_cset_region_length(), "invariant");
6089       size_t words_survived = _surviving_young_words[index];
6090       cur->record_surv_words_in_group(words_survived);
6091 
6092       // At this point the we have 'popped' cur from the collection set
6093       // (linked via next_in_collection_set()) but it is still in the
6094       // young list (linked via next_young_region()). Clear the
6095       // _next_young_region field.
6096       cur->set_next_young_region(NULL);
6097     } else {
6098       int index = cur->young_index_in_cset();
6099       assert(index == -1, "invariant");
6100     }
6101 
6102     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6103             (!cur->is_young() && cur->young_index_in_cset() == -1),
6104             "invariant" );
6105 
6106     if (!cur->evacuation_failed()) {
6107       MemRegion used_mr = cur->used_region();
6108 
6109       // And the region is empty.
6110       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6111       free_region(cur, &pre_used, &local_free_list, false /* par */);
6112     } else {
6113       cur->uninstall_surv_rate_group();
6114       if (cur->is_young()) {
6115         cur->set_young_index_in_cset(-1);
6116       }
6117       cur->set_not_young();
6118       cur->set_evacuation_failed(false);
6119       // The region is now considered to be old.
6120       _old_set.add(cur);
6121       evacuation_info.increment_collectionset_used_after(cur->used());
6122     }
6123     cur = next;
6124   }
6125 
6126   evacuation_info.set_regions_freed(local_free_list.length());
6127   policy->record_max_rs_lengths(rs_lengths);
6128   policy->cset_regions_freed();
6129 
6130   double end_sec = os::elapsedTime();
6131   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6132 
6133   if (non_young) {
6134     non_young_time_ms += elapsed_ms;
6135   } else {
6136     young_time_ms += elapsed_ms;
6137   }
6138 
6139   update_sets_after_freeing_regions(pre_used, &local_free_list,
6140                                     NULL /* old_proxy_set */,
6141                                     NULL /* humongous_proxy_set */,
6142                                     false /* par */);
6143   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6144   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6145 }
6146 
6147 // This routine is similar to the above but does not record
6148 // any policy statistics or update free lists; we are abandoning
6149 // the current incremental collection set in preparation of a
6150 // full collection. After the full GC we will start to build up
6151 // the incremental collection set again.
6152 // This is only called when we're doing a full collection
6153 // and is immediately followed by the tearing down of the young list.
6154 
6155 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6156   HeapRegion* cur = cs_head;
6157 
6158   while (cur != NULL) {
6159     HeapRegion* next = cur->next_in_collection_set();
6160     assert(cur->in_collection_set(), "bad CS");
6161     cur->set_next_in_collection_set(NULL);
6162     cur->set_in_collection_set(false);
6163     cur->set_young_index_in_cset(-1);
6164     cur = next;
6165   }
6166 }
6167 
6168 void G1CollectedHeap::set_free_regions_coming() {
6169   if (G1ConcRegionFreeingVerbose) {
6170     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6171                            "setting free regions coming");
6172   }
6173 
6174   assert(!free_regions_coming(), "pre-condition");
6175   _free_regions_coming = true;
6176 }
6177 
6178 void G1CollectedHeap::reset_free_regions_coming() {
6179   assert(free_regions_coming(), "pre-condition");
6180 
6181   {
6182     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6183     _free_regions_coming = false;
6184     SecondaryFreeList_lock->notify_all();
6185   }
6186 
6187   if (G1ConcRegionFreeingVerbose) {
6188     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6189                            "reset free regions coming");
6190   }
6191 }
6192 
6193 void G1CollectedHeap::wait_while_free_regions_coming() {
6194   // Most of the time we won't have to wait, so let's do a quick test
6195   // first before we take the lock.
6196   if (!free_regions_coming()) {
6197     return;
6198   }
6199 
6200   if (G1ConcRegionFreeingVerbose) {
6201     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6202                            "waiting for free regions");
6203   }
6204 
6205   {
6206     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6207     while (free_regions_coming()) {
6208       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6209     }
6210   }
6211 
6212   if (G1ConcRegionFreeingVerbose) {
6213     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6214                            "done waiting for free regions");
6215   }
6216 }
6217 
6218 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6219   assert(heap_lock_held_for_gc(),
6220               "the heap lock should already be held by or for this thread");
6221   _young_list->push_region(hr);
6222 }
6223 
6224 class NoYoungRegionsClosure: public HeapRegionClosure {
6225 private:
6226   bool _success;
6227 public:
6228   NoYoungRegionsClosure() : _success(true) { }
6229   bool doHeapRegion(HeapRegion* r) {
6230     if (r->is_young()) {
6231       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6232                              r->bottom(), r->end());
6233       _success = false;
6234     }
6235     return false;
6236   }
6237   bool success() { return _success; }
6238 };
6239 
6240 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6241   bool ret = _young_list->check_list_empty(check_sample);
6242 
6243   if (check_heap) {
6244     NoYoungRegionsClosure closure;
6245     heap_region_iterate(&closure);
6246     ret = ret && closure.success();
6247   }
6248 
6249   return ret;
6250 }
6251 
6252 class TearDownRegionSetsClosure : public HeapRegionClosure {
6253 private:
6254   OldRegionSet *_old_set;
6255 
6256 public:
6257   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6258 
6259   bool doHeapRegion(HeapRegion* r) {
6260     if (r->is_empty()) {
6261       // We ignore empty regions, we'll empty the free list afterwards
6262     } else if (r->is_young()) {
6263       // We ignore young regions, we'll empty the young list afterwards
6264     } else if (r->isHumongous()) {
6265       // We ignore humongous regions, we're not tearing down the
6266       // humongous region set
6267     } else {
6268       // The rest should be old
6269       _old_set->remove(r);
6270     }
6271     return false;
6272   }
6273 
6274   ~TearDownRegionSetsClosure() {
6275     assert(_old_set->is_empty(), "post-condition");
6276   }
6277 };
6278 
6279 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6280   assert_at_safepoint(true /* should_be_vm_thread */);
6281 
6282   if (!free_list_only) {
6283     TearDownRegionSetsClosure cl(&_old_set);
6284     heap_region_iterate(&cl);
6285 
6286     // Need to do this after the heap iteration to be able to
6287     // recognize the young regions and ignore them during the iteration.
6288     _young_list->empty_list();
6289   }
6290   _free_list.remove_all();
6291 }
6292 
6293 class RebuildRegionSetsClosure : public HeapRegionClosure {
6294 private:
6295   bool            _free_list_only;
6296   OldRegionSet*   _old_set;
6297   FreeRegionList* _free_list;
6298   size_t          _total_used;
6299 
6300 public:
6301   RebuildRegionSetsClosure(bool free_list_only,
6302                            OldRegionSet* old_set, FreeRegionList* free_list) :
6303     _free_list_only(free_list_only),
6304     _old_set(old_set), _free_list(free_list), _total_used(0) {
6305     assert(_free_list->is_empty(), "pre-condition");
6306     if (!free_list_only) {
6307       assert(_old_set->is_empty(), "pre-condition");
6308     }
6309   }
6310 
6311   bool doHeapRegion(HeapRegion* r) {
6312     if (r->continuesHumongous()) {
6313       return false;
6314     }
6315 
6316     if (r->is_empty()) {
6317       // Add free regions to the free list
6318       _free_list->add_as_tail(r);
6319     } else if (!_free_list_only) {
6320       assert(!r->is_young(), "we should not come across young regions");
6321 
6322       if (r->isHumongous()) {
6323         // We ignore humongous regions, we left the humongous set unchanged
6324       } else {
6325         // The rest should be old, add them to the old set
6326         _old_set->add(r);
6327       }
6328       _total_used += r->used();
6329     }
6330 
6331     return false;
6332   }
6333 
6334   size_t total_used() {
6335     return _total_used;
6336   }
6337 };
6338 
6339 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6340   assert_at_safepoint(true /* should_be_vm_thread */);
6341 
6342   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6343   heap_region_iterate(&cl);
6344 
6345   if (!free_list_only) {
6346     _summary_bytes_used = cl.total_used();
6347   }
6348   assert(_summary_bytes_used == recalculate_used(),
6349          err_msg("inconsistent _summary_bytes_used, "
6350                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6351                  _summary_bytes_used, recalculate_used()));
6352 }
6353 
6354 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6355   _refine_cte_cl->set_concurrent(concurrent);
6356 }
6357 
6358 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6359   HeapRegion* hr = heap_region_containing(p);
6360   if (hr == NULL) {
6361     return false;
6362   } else {
6363     return hr->is_in(p);
6364   }
6365 }
6366 
6367 // Methods for the mutator alloc region
6368 
6369 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6370                                                       bool force) {
6371   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6372   assert(!force || g1_policy()->can_expand_young_list(),
6373          "if force is true we should be able to expand the young list");
6374   bool young_list_full = g1_policy()->is_young_list_full();
6375   if (force || !young_list_full) {
6376     HeapRegion* new_alloc_region = new_region(word_size,
6377                                               false /* do_expand */);
6378     if (new_alloc_region != NULL) {
6379       set_region_short_lived_locked(new_alloc_region);
6380       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6381       return new_alloc_region;
6382     }
6383   }
6384   return NULL;
6385 }
6386 
6387 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6388                                                   size_t allocated_bytes) {
6389   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6390   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6391 
6392   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6393   _summary_bytes_used += allocated_bytes;
6394   _hr_printer.retire(alloc_region);
6395   // We update the eden sizes here, when the region is retired,
6396   // instead of when it's allocated, since this is the point that its
6397   // used space has been recored in _summary_bytes_used.
6398   g1mm()->update_eden_size();
6399 }
6400 
6401 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6402                                                     bool force) {
6403   return _g1h->new_mutator_alloc_region(word_size, force);
6404 }
6405 
6406 void G1CollectedHeap::set_par_threads() {
6407   // Don't change the number of workers.  Use the value previously set
6408   // in the workgroup.
6409   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6410   uint n_workers = workers()->active_workers();
6411   assert(UseDynamicNumberOfGCThreads ||
6412            n_workers == workers()->total_workers(),
6413       "Otherwise should be using the total number of workers");
6414   if (n_workers == 0) {
6415     assert(false, "Should have been set in prior evacuation pause.");
6416     n_workers = ParallelGCThreads;
6417     workers()->set_active_workers(n_workers);
6418   }
6419   set_par_threads(n_workers);
6420 }
6421 
6422 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6423                                        size_t allocated_bytes) {
6424   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6425 }
6426 
6427 // Methods for the GC alloc regions
6428 
6429 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6430                                                  uint count,
6431                                                  GCAllocPurpose ap) {
6432   assert(FreeList_lock->owned_by_self(), "pre-condition");
6433 
6434   if (count < g1_policy()->max_regions(ap)) {
6435     HeapRegion* new_alloc_region = new_region(word_size,
6436                                               true /* do_expand */);
6437     if (new_alloc_region != NULL) {
6438       // We really only need to do this for old regions given that we
6439       // should never scan survivors. But it doesn't hurt to do it
6440       // for survivors too.
6441       new_alloc_region->set_saved_mark();
6442       if (ap == GCAllocForSurvived) {
6443         new_alloc_region->set_survivor();
6444         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6445       } else {
6446         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6447       }
6448       bool during_im = g1_policy()->during_initial_mark_pause();
6449       new_alloc_region->note_start_of_copying(during_im);
6450       return new_alloc_region;
6451     } else {
6452       g1_policy()->note_alloc_region_limit_reached(ap);
6453     }
6454   }
6455   return NULL;
6456 }
6457 
6458 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6459                                              size_t allocated_bytes,
6460                                              GCAllocPurpose ap) {
6461   bool during_im = g1_policy()->during_initial_mark_pause();
6462   alloc_region->note_end_of_copying(during_im);
6463   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6464   if (ap == GCAllocForSurvived) {
6465     young_list()->add_survivor_region(alloc_region);
6466   } else {
6467     _old_set.add(alloc_region);
6468   }
6469   _hr_printer.retire(alloc_region);
6470 }
6471 
6472 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6473                                                        bool force) {
6474   assert(!force, "not supported for GC alloc regions");
6475   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6476 }
6477 
6478 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6479                                           size_t allocated_bytes) {
6480   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6481                                GCAllocForSurvived);
6482 }
6483 
6484 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6485                                                   bool force) {
6486   assert(!force, "not supported for GC alloc regions");
6487   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6488 }
6489 
6490 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6491                                      size_t allocated_bytes) {
6492   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6493                                GCAllocForTenured);
6494 }
6495 // Heap region set verification
6496 
6497 class VerifyRegionListsClosure : public HeapRegionClosure {
6498 private:
6499   FreeRegionList*     _free_list;
6500   OldRegionSet*       _old_set;
6501   HumongousRegionSet* _humongous_set;
6502   uint                _region_count;
6503 
6504 public:
6505   VerifyRegionListsClosure(OldRegionSet* old_set,
6506                            HumongousRegionSet* humongous_set,
6507                            FreeRegionList* free_list) :
6508     _old_set(old_set), _humongous_set(humongous_set),
6509     _free_list(free_list), _region_count(0) { }
6510 
6511   uint region_count() { return _region_count; }
6512 
6513   bool doHeapRegion(HeapRegion* hr) {
6514     _region_count += 1;
6515 
6516     if (hr->continuesHumongous()) {
6517       return false;
6518     }
6519 
6520     if (hr->is_young()) {
6521       // TODO
6522     } else if (hr->startsHumongous()) {
6523       _humongous_set->verify_next_region(hr);
6524     } else if (hr->is_empty()) {
6525       _free_list->verify_next_region(hr);
6526     } else {
6527       _old_set->verify_next_region(hr);
6528     }
6529     return false;
6530   }
6531 };
6532 
6533 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6534                                              HeapWord* bottom) {
6535   HeapWord* end = bottom + HeapRegion::GrainWords;
6536   MemRegion mr(bottom, end);
6537   assert(_g1_reserved.contains(mr), "invariant");
6538   // This might return NULL if the allocation fails
6539   return new HeapRegion(hrs_index, _bot_shared, mr);
6540 }
6541 
6542 void G1CollectedHeap::verify_region_sets() {
6543   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6544 
6545   // First, check the explicit lists.
6546   _free_list.verify();
6547   {
6548     // Given that a concurrent operation might be adding regions to
6549     // the secondary free list we have to take the lock before
6550     // verifying it.
6551     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6552     _secondary_free_list.verify();
6553   }
6554   _old_set.verify();
6555   _humongous_set.verify();
6556 
6557   // If a concurrent region freeing operation is in progress it will
6558   // be difficult to correctly attributed any free regions we come
6559   // across to the correct free list given that they might belong to
6560   // one of several (free_list, secondary_free_list, any local lists,
6561   // etc.). So, if that's the case we will skip the rest of the
6562   // verification operation. Alternatively, waiting for the concurrent
6563   // operation to complete will have a non-trivial effect on the GC's
6564   // operation (no concurrent operation will last longer than the
6565   // interval between two calls to verification) and it might hide
6566   // any issues that we would like to catch during testing.
6567   if (free_regions_coming()) {
6568     return;
6569   }
6570 
6571   // Make sure we append the secondary_free_list on the free_list so
6572   // that all free regions we will come across can be safely
6573   // attributed to the free_list.
6574   append_secondary_free_list_if_not_empty_with_lock();
6575 
6576   // Finally, make sure that the region accounting in the lists is
6577   // consistent with what we see in the heap.
6578   _old_set.verify_start();
6579   _humongous_set.verify_start();
6580   _free_list.verify_start();
6581 
6582   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6583   heap_region_iterate(&cl);
6584 
6585   _old_set.verify_end();
6586   _humongous_set.verify_end();
6587   _free_list.verify_end();
6588 }
--- EOF ---