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/heapRegion.inline.hpp"
  42 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  43 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  44 #include "gc_implementation/g1/vm_operations_g1.hpp"
  45 #include "gc_implementation/shared/isGCActiveMark.hpp"
  46 #include "memory/gcLocker.inline.hpp"
  47 #include "memory/genOopClosures.inline.hpp"
  48 #include "memory/generationSpec.hpp"
  49 #include "memory/referenceProcessor.hpp"
  50 #include "oops/oop.inline.hpp"
  51 #include "oops/oop.pcgc.inline.hpp"
  52 #include "runtime/aprofiler.hpp"
  53 #include "runtime/vmThread.hpp"
  54 
  55 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  56 
  57 // turn it on so that the contents of the young list (scan-only /
  58 // to-be-collected) are printed at "strategic" points before / during
  59 // / after the collection --- this is useful for debugging
  60 #define YOUNG_LIST_VERBOSE 0
  61 // CURRENT STATUS
  62 // This file is under construction.  Search for "FIXME".
  63 
  64 // INVARIANTS/NOTES
  65 //
  66 // All allocation activity covered by the G1CollectedHeap interface is
  67 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  68 // and allocate_new_tlab, which are the "entry" points to the
  69 // allocation code from the rest of the JVM.  (Note that this does not
  70 // apply to TLAB allocation, which is not part of this interface: it
  71 // is done by clients of this interface.)
  72 
  73 // Notes on implementation of parallelism in different tasks.
  74 //
  75 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  76 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  77 // It does use run_task() which sets _n_workers in the task.
  78 // G1ParTask executes g1_process_strong_roots() ->
  79 // SharedHeap::process_strong_roots() which calls eventuall to
  80 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  81 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  82 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  83 //
  84 
  85 // Local to this file.
  86 
  87 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  88   SuspendibleThreadSet* _sts;
  89   G1RemSet* _g1rs;
  90   ConcurrentG1Refine* _cg1r;
  91   bool _concurrent;
  92 public:
  93   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  94                               G1RemSet* g1rs,
  95                               ConcurrentG1Refine* cg1r) :
  96     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
  97   {}
  98   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
  99     bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
 100     // This path is executed by the concurrent refine or mutator threads,
 101     // concurrently, and so we do not care if card_ptr contains references
 102     // that point into the collection set.
 103     assert(!oops_into_cset, "should be");
 104 
 105     if (_concurrent && _sts->should_yield()) {
 106       // Caller will actually yield.
 107       return false;
 108     }
 109     // Otherwise, we finished successfully; return true.
 110     return true;
 111   }
 112   void set_concurrent(bool b) { _concurrent = b; }
 113 };
 114 
 115 
 116 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 117   int _calls;
 118   G1CollectedHeap* _g1h;
 119   CardTableModRefBS* _ctbs;
 120   int _histo[256];
 121 public:
 122   ClearLoggedCardTableEntryClosure() :
 123     _calls(0)
 124   {
 125     _g1h = G1CollectedHeap::heap();
 126     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 127     for (int i = 0; i < 256; i++) _histo[i] = 0;
 128   }
 129   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 130     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 131       _calls++;
 132       unsigned char* ujb = (unsigned char*)card_ptr;
 133       int ind = (int)(*ujb);
 134       _histo[ind]++;
 135       *card_ptr = -1;
 136     }
 137     return true;
 138   }
 139   int calls() { return _calls; }
 140   void print_histo() {
 141     gclog_or_tty->print_cr("Card table value histogram:");
 142     for (int i = 0; i < 256; i++) {
 143       if (_histo[i] != 0) {
 144         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 145       }
 146     }
 147   }
 148 };
 149 
 150 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 151   int _calls;
 152   G1CollectedHeap* _g1h;
 153   CardTableModRefBS* _ctbs;
 154 public:
 155   RedirtyLoggedCardTableEntryClosure() :
 156     _calls(0)
 157   {
 158     _g1h = G1CollectedHeap::heap();
 159     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 160   }
 161   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 162     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 163       _calls++;
 164       *card_ptr = 0;
 165     }
 166     return true;
 167   }
 168   int calls() { return _calls; }
 169 };
 170 
 171 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 172 public:
 173   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 174     *card_ptr = CardTableModRefBS::dirty_card_val();
 175     return true;
 176   }
 177 };
 178 
 179 YoungList::YoungList(G1CollectedHeap* g1h) :
 180     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 181     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 182   guarantee(check_list_empty(false), "just making sure...");
 183 }
 184 
 185 void YoungList::push_region(HeapRegion *hr) {
 186   assert(!hr->is_young(), "should not already be young");
 187   assert(hr->get_next_young_region() == NULL, "cause it should!");
 188 
 189   hr->set_next_young_region(_head);
 190   _head = hr;
 191 
 192   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 193   ++_length;
 194 }
 195 
 196 void YoungList::add_survivor_region(HeapRegion* hr) {
 197   assert(hr->is_survivor(), "should be flagged as survivor region");
 198   assert(hr->get_next_young_region() == NULL, "cause it should!");
 199 
 200   hr->set_next_young_region(_survivor_head);
 201   if (_survivor_head == NULL) {
 202     _survivor_tail = hr;
 203   }
 204   _survivor_head = hr;
 205   ++_survivor_length;
 206 }
 207 
 208 void YoungList::empty_list(HeapRegion* list) {
 209   while (list != NULL) {
 210     HeapRegion* next = list->get_next_young_region();
 211     list->set_next_young_region(NULL);
 212     list->uninstall_surv_rate_group();
 213     list->set_not_young();
 214     list = next;
 215   }
 216 }
 217 
 218 void YoungList::empty_list() {
 219   assert(check_list_well_formed(), "young list should be well formed");
 220 
 221   empty_list(_head);
 222   _head = NULL;
 223   _length = 0;
 224 
 225   empty_list(_survivor_head);
 226   _survivor_head = NULL;
 227   _survivor_tail = NULL;
 228   _survivor_length = 0;
 229 
 230   _last_sampled_rs_lengths = 0;
 231 
 232   assert(check_list_empty(false), "just making sure...");
 233 }
 234 
 235 bool YoungList::check_list_well_formed() {
 236   bool ret = true;
 237 
 238   uint length = 0;
 239   HeapRegion* curr = _head;
 240   HeapRegion* last = NULL;
 241   while (curr != NULL) {
 242     if (!curr->is_young()) {
 243       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 244                              "incorrectly tagged (y: %d, surv: %d)",
 245                              curr->bottom(), curr->end(),
 246                              curr->is_young(), curr->is_survivor());
 247       ret = false;
 248     }
 249     ++length;
 250     last = curr;
 251     curr = curr->get_next_young_region();
 252   }
 253   ret = ret && (length == _length);
 254 
 255   if (!ret) {
 256     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 257     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 258                            length, _length);
 259   }
 260 
 261   return ret;
 262 }
 263 
 264 bool YoungList::check_list_empty(bool check_sample) {
 265   bool ret = true;
 266 
 267   if (_length != 0) {
 268     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 269                   _length);
 270     ret = false;
 271   }
 272   if (check_sample && _last_sampled_rs_lengths != 0) {
 273     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 274     ret = false;
 275   }
 276   if (_head != NULL) {
 277     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 278     ret = false;
 279   }
 280   if (!ret) {
 281     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 282   }
 283 
 284   return ret;
 285 }
 286 
 287 void
 288 YoungList::rs_length_sampling_init() {
 289   _sampled_rs_lengths = 0;
 290   _curr               = _head;
 291 }
 292 
 293 bool
 294 YoungList::rs_length_sampling_more() {
 295   return _curr != NULL;
 296 }
 297 
 298 void
 299 YoungList::rs_length_sampling_next() {
 300   assert( _curr != NULL, "invariant" );
 301   size_t rs_length = _curr->rem_set()->occupied();
 302 
 303   _sampled_rs_lengths += rs_length;
 304 
 305   // The current region may not yet have been added to the
 306   // incremental collection set (it gets added when it is
 307   // retired as the current allocation region).
 308   if (_curr->in_collection_set()) {
 309     // Update the collection set policy information for this region
 310     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 311   }
 312 
 313   _curr = _curr->get_next_young_region();
 314   if (_curr == NULL) {
 315     _last_sampled_rs_lengths = _sampled_rs_lengths;
 316     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 317   }
 318 }
 319 
 320 void
 321 YoungList::reset_auxilary_lists() {
 322   guarantee( is_empty(), "young list should be empty" );
 323   assert(check_list_well_formed(), "young list should be well formed");
 324 
 325   // Add survivor regions to SurvRateGroup.
 326   _g1h->g1_policy()->note_start_adding_survivor_regions();
 327   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 328 
 329   int young_index_in_cset = 0;
 330   for (HeapRegion* curr = _survivor_head;
 331        curr != NULL;
 332        curr = curr->get_next_young_region()) {
 333     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 334 
 335     // The region is a non-empty survivor so let's add it to
 336     // the incremental collection set for the next evacuation
 337     // pause.
 338     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 339     young_index_in_cset += 1;
 340   }
 341   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 342   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 343 
 344   _head   = _survivor_head;
 345   _length = _survivor_length;
 346   if (_survivor_head != NULL) {
 347     assert(_survivor_tail != NULL, "cause it shouldn't be");
 348     assert(_survivor_length > 0, "invariant");
 349     _survivor_tail->set_next_young_region(NULL);
 350   }
 351 
 352   // Don't clear the survivor list handles until the start of
 353   // the next evacuation pause - we need it in order to re-tag
 354   // the survivor regions from this evacuation pause as 'young'
 355   // at the start of the next.
 356 
 357   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 358 
 359   assert(check_list_well_formed(), "young list should be well formed");
 360 }
 361 
 362 void YoungList::print() {
 363   HeapRegion* lists[] = {_head,   _survivor_head};
 364   const char* names[] = {"YOUNG", "SURVIVOR"};
 365 
 366   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 367     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 368     HeapRegion *curr = lists[list];
 369     if (curr == NULL)
 370       gclog_or_tty->print_cr("  empty");
 371     while (curr != NULL) {
 372       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 373                              HR_FORMAT_PARAMS(curr),
 374                              curr->prev_top_at_mark_start(),
 375                              curr->next_top_at_mark_start(),
 376                              curr->age_in_surv_rate_group_cond());
 377       curr = curr->get_next_young_region();
 378     }
 379   }
 380 
 381   gclog_or_tty->print_cr("");
 382 }
 383 
 384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 385 {
 386   // Claim the right to put the region on the dirty cards region list
 387   // by installing a self pointer.
 388   HeapRegion* next = hr->get_next_dirty_cards_region();
 389   if (next == NULL) {
 390     HeapRegion* res = (HeapRegion*)
 391       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 392                           NULL);
 393     if (res == NULL) {
 394       HeapRegion* head;
 395       do {
 396         // Put the region to the dirty cards region list.
 397         head = _dirty_cards_region_list;
 398         next = (HeapRegion*)
 399           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 400         if (next == head) {
 401           assert(hr->get_next_dirty_cards_region() == hr,
 402                  "hr->get_next_dirty_cards_region() != hr");
 403           if (next == NULL) {
 404             // The last region in the list points to itself.
 405             hr->set_next_dirty_cards_region(hr);
 406           } else {
 407             hr->set_next_dirty_cards_region(next);
 408           }
 409         }
 410       } while (next != head);
 411     }
 412   }
 413 }
 414 
 415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 416 {
 417   HeapRegion* head;
 418   HeapRegion* hr;
 419   do {
 420     head = _dirty_cards_region_list;
 421     if (head == NULL) {
 422       return NULL;
 423     }
 424     HeapRegion* new_head = head->get_next_dirty_cards_region();
 425     if (head == new_head) {
 426       // The last region.
 427       new_head = NULL;
 428     }
 429     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 430                                           head);
 431   } while (hr != head);
 432   assert(hr != NULL, "invariant");
 433   hr->set_next_dirty_cards_region(NULL);
 434   return hr;
 435 }
 436 
 437 void G1CollectedHeap::stop_conc_gc_threads() {
 438   _cg1r->stop();
 439   _cmThread->stop();
 440 }
 441 
 442 #ifdef ASSERT
 443 // A region is added to the collection set as it is retired
 444 // so an address p can point to a region which will be in the
 445 // collection set but has not yet been retired.  This method
 446 // therefore is only accurate during a GC pause after all
 447 // regions have been retired.  It is used for debugging
 448 // to check if an nmethod has references to objects that can
 449 // be move during a partial collection.  Though it can be
 450 // inaccurate, it is sufficient for G1 because the conservative
 451 // implementation of is_scavengable() for G1 will indicate that
 452 // all nmethods must be scanned during a partial collection.
 453 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 454   HeapRegion* hr = heap_region_containing(p);
 455   return hr != NULL && hr->in_collection_set();
 456 }
 457 #endif
 458 
 459 // Returns true if the reference points to an object that
 460 // can move in an incremental collecction.
 461 bool G1CollectedHeap::is_scavengable(const void* p) {
 462   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 463   G1CollectorPolicy* g1p = g1h->g1_policy();
 464   HeapRegion* hr = heap_region_containing(p);
 465   if (hr == NULL) {
 466      // null
 467      assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
 468      return false;
 469   } else {
 470     return !hr->isHumongous();
 471   }
 472 }
 473 
 474 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 475   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 476   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
 477 
 478   // Count the dirty cards at the start.
 479   CountNonCleanMemRegionClosure count1(this);
 480   ct_bs->mod_card_iterate(&count1);
 481   int orig_count = count1.n();
 482 
 483   // First clear the logged cards.
 484   ClearLoggedCardTableEntryClosure clear;
 485   dcqs.set_closure(&clear);
 486   dcqs.apply_closure_to_all_completed_buffers();
 487   dcqs.iterate_closure_all_threads(false);
 488   clear.print_histo();
 489 
 490   // Now ensure that there's no dirty cards.
 491   CountNonCleanMemRegionClosure count2(this);
 492   ct_bs->mod_card_iterate(&count2);
 493   if (count2.n() != 0) {
 494     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 495                            count2.n(), orig_count);
 496   }
 497   guarantee(count2.n() == 0, "Card table should be clean.");
 498 
 499   RedirtyLoggedCardTableEntryClosure redirty;
 500   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 501   dcqs.apply_closure_to_all_completed_buffers();
 502   dcqs.iterate_closure_all_threads(false);
 503   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 504                          clear.calls(), orig_count);
 505   guarantee(redirty.calls() == clear.calls(),
 506             "Or else mechanism is broken.");
 507 
 508   CountNonCleanMemRegionClosure count3(this);
 509   ct_bs->mod_card_iterate(&count3);
 510   if (count3.n() != orig_count) {
 511     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 512                            orig_count, count3.n());
 513     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 514   }
 515 
 516   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 517 }
 518 
 519 // Private class members.
 520 
 521 G1CollectedHeap* G1CollectedHeap::_g1h;
 522 
 523 // Private methods.
 524 
 525 HeapRegion*
 526 G1CollectedHeap::new_region_try_secondary_free_list() {
 527   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 528   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 529     if (!_secondary_free_list.is_empty()) {
 530       if (G1ConcRegionFreeingVerbose) {
 531         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 532                                "secondary_free_list has %u entries",
 533                                _secondary_free_list.length());
 534       }
 535       // It looks as if there are free regions available on the
 536       // secondary_free_list. Let's move them to the free_list and try
 537       // again to allocate from it.
 538       append_secondary_free_list();
 539 
 540       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 541              "empty we should have moved at least one entry to the free_list");
 542       HeapRegion* res = _free_list.remove_head();
 543       if (G1ConcRegionFreeingVerbose) {
 544         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 545                                "allocated "HR_FORMAT" from secondary_free_list",
 546                                HR_FORMAT_PARAMS(res));
 547       }
 548       return res;
 549     }
 550 
 551     // Wait here until we get notifed either when (a) there are no
 552     // more free regions coming or (b) some regions have been moved on
 553     // the secondary_free_list.
 554     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 555   }
 556 
 557   if (G1ConcRegionFreeingVerbose) {
 558     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 559                            "could not allocate from secondary_free_list");
 560   }
 561   return NULL;
 562 }
 563 
 564 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 565   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 566          "the only time we use this to allocate a humongous region is "
 567          "when we are allocating a single humongous region");
 568 
 569   HeapRegion* res;
 570   if (G1StressConcRegionFreeing) {
 571     if (!_secondary_free_list.is_empty()) {
 572       if (G1ConcRegionFreeingVerbose) {
 573         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 574                                "forced to look at the secondary_free_list");
 575       }
 576       res = new_region_try_secondary_free_list();
 577       if (res != NULL) {
 578         return res;
 579       }
 580     }
 581   }
 582   res = _free_list.remove_head_or_null();
 583   if (res == NULL) {
 584     if (G1ConcRegionFreeingVerbose) {
 585       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 586                              "res == NULL, trying the secondary_free_list");
 587     }
 588     res = new_region_try_secondary_free_list();
 589   }
 590   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 591     // Currently, only attempts to allocate GC alloc regions set
 592     // do_expand to true. So, we should only reach here during a
 593     // safepoint. If this assumption changes we might have to
 594     // reconsider the use of _expand_heap_after_alloc_failure.
 595     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 596 
 597     ergo_verbose1(ErgoHeapSizing,
 598                   "attempt heap expansion",
 599                   ergo_format_reason("region allocation request failed")
 600                   ergo_format_byte("allocation request"),
 601                   word_size * HeapWordSize);
 602     if (expand(word_size * HeapWordSize)) {
 603       // Given that expand() succeeded in expanding the heap, and we
 604       // always expand the heap by an amount aligned to the heap
 605       // region size, the free list should in theory not be empty. So
 606       // it would probably be OK to use remove_head(). But the extra
 607       // check for NULL is unlikely to be a performance issue here (we
 608       // just expanded the heap!) so let's just be conservative and
 609       // use remove_head_or_null().
 610       res = _free_list.remove_head_or_null();
 611     } else {
 612       _expand_heap_after_alloc_failure = false;
 613     }
 614   }
 615   return res;
 616 }
 617 
 618 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 619                                                         size_t word_size) {
 620   assert(isHumongous(word_size), "word_size should be humongous");
 621   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 622 
 623   uint first = G1_NULL_HRS_INDEX;
 624   if (num_regions == 1) {
 625     // Only one region to allocate, no need to go through the slower
 626     // path. The caller will attempt the expasion if this fails, so
 627     // let's not try to expand here too.
 628     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 629     if (hr != NULL) {
 630       first = hr->hrs_index();
 631     } else {
 632       first = G1_NULL_HRS_INDEX;
 633     }
 634   } else {
 635     // We can't allocate humongous regions while cleanupComplete() is
 636     // running, since some of the regions we find to be empty might not
 637     // yet be added to the free list and it is not straightforward to
 638     // know which list they are on so that we can remove them. Note
 639     // that we only need to do this if we need to allocate more than
 640     // one region to satisfy the current humongous allocation
 641     // request. If we are only allocating one region we use the common
 642     // region allocation code (see above).
 643     wait_while_free_regions_coming();
 644     append_secondary_free_list_if_not_empty_with_lock();
 645 
 646     if (free_regions() >= num_regions) {
 647       first = _hrs.find_contiguous(num_regions);
 648       if (first != G1_NULL_HRS_INDEX) {
 649         for (uint i = first; i < first + num_regions; ++i) {
 650           HeapRegion* hr = region_at(i);
 651           assert(hr->is_empty(), "sanity");
 652           assert(is_on_master_free_list(hr), "sanity");
 653           hr->set_pending_removal(true);
 654         }
 655         _free_list.remove_all_pending(num_regions);
 656       }
 657     }
 658   }
 659   return first;
 660 }
 661 
 662 HeapWord*
 663 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 664                                                            uint num_regions,
 665                                                            size_t word_size) {
 666   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 667   assert(isHumongous(word_size), "word_size should be humongous");
 668   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 669 
 670   // Index of last region in the series + 1.
 671   uint last = first + num_regions;
 672 
 673   // We need to initialize the region(s) we just discovered. This is
 674   // a bit tricky given that it can happen concurrently with
 675   // refinement threads refining cards on these regions and
 676   // potentially wanting to refine the BOT as they are scanning
 677   // those cards (this can happen shortly after a cleanup; see CR
 678   // 6991377). So we have to set up the region(s) carefully and in
 679   // a specific order.
 680 
 681   // The word size sum of all the regions we will allocate.
 682   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 683   assert(word_size <= word_size_sum, "sanity");
 684 
 685   // This will be the "starts humongous" region.
 686   HeapRegion* first_hr = region_at(first);
 687   // The header of the new object will be placed at the bottom of
 688   // the first region.
 689   HeapWord* new_obj = first_hr->bottom();
 690   // This will be the new end of the first region in the series that
 691   // should also match the end of the last region in the seriers.
 692   HeapWord* new_end = new_obj + word_size_sum;
 693   // This will be the new top of the first region that will reflect
 694   // this allocation.
 695   HeapWord* new_top = new_obj + word_size;
 696 
 697   // First, we need to zero the header of the space that we will be
 698   // allocating. When we update top further down, some refinement
 699   // threads might try to scan the region. By zeroing the header we
 700   // ensure that any thread that will try to scan the region will
 701   // come across the zero klass word and bail out.
 702   //
 703   // NOTE: It would not have been correct to have used
 704   // CollectedHeap::fill_with_object() and make the space look like
 705   // an int array. The thread that is doing the allocation will
 706   // later update the object header to a potentially different array
 707   // type and, for a very short period of time, the klass and length
 708   // fields will be inconsistent. This could cause a refinement
 709   // thread to calculate the object size incorrectly.
 710   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 711 
 712   // We will set up the first region as "starts humongous". This
 713   // will also update the BOT covering all the regions to reflect
 714   // that there is a single object that starts at the bottom of the
 715   // first region.
 716   first_hr->set_startsHumongous(new_top, new_end);
 717 
 718   // Then, if there are any, we will set up the "continues
 719   // humongous" regions.
 720   HeapRegion* hr = NULL;
 721   for (uint i = first + 1; i < last; ++i) {
 722     hr = region_at(i);
 723     hr->set_continuesHumongous(first_hr);
 724   }
 725   // If we have "continues humongous" regions (hr != NULL), then the
 726   // end of the last one should match new_end.
 727   assert(hr == NULL || hr->end() == new_end, "sanity");
 728 
 729   // Up to this point no concurrent thread would have been able to
 730   // do any scanning on any region in this series. All the top
 731   // fields still point to bottom, so the intersection between
 732   // [bottom,top] and [card_start,card_end] will be empty. Before we
 733   // update the top fields, we'll do a storestore to make sure that
 734   // no thread sees the update to top before the zeroing of the
 735   // object header and the BOT initialization.
 736   OrderAccess::storestore();
 737 
 738   // Now that the BOT and the object header have been initialized,
 739   // we can update top of the "starts humongous" region.
 740   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 741          "new_top should be in this region");
 742   first_hr->set_top(new_top);
 743   if (_hr_printer.is_active()) {
 744     HeapWord* bottom = first_hr->bottom();
 745     HeapWord* end = first_hr->orig_end();
 746     if ((first + 1) == last) {
 747       // the series has a single humongous region
 748       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 749     } else {
 750       // the series has more than one humongous regions
 751       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 752     }
 753   }
 754 
 755   // Now, we will update the top fields of the "continues humongous"
 756   // regions. The reason we need to do this is that, otherwise,
 757   // these regions would look empty and this will confuse parts of
 758   // G1. For example, the code that looks for a consecutive number
 759   // of empty regions will consider them empty and try to
 760   // re-allocate them. We can extend is_empty() to also include
 761   // !continuesHumongous(), but it is easier to just update the top
 762   // fields here. The way we set top for all regions (i.e., top ==
 763   // end for all regions but the last one, top == new_top for the
 764   // last one) is actually used when we will free up the humongous
 765   // region in free_humongous_region().
 766   hr = NULL;
 767   for (uint i = first + 1; i < last; ++i) {
 768     hr = region_at(i);
 769     if ((i + 1) == last) {
 770       // last continues humongous region
 771       assert(hr->bottom() < new_top && new_top <= hr->end(),
 772              "new_top should fall on this region");
 773       hr->set_top(new_top);
 774       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 775     } else {
 776       // not last one
 777       assert(new_top > hr->end(), "new_top should be above this region");
 778       hr->set_top(hr->end());
 779       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 780     }
 781   }
 782   // If we have continues humongous regions (hr != NULL), then the
 783   // end of the last one should match new_end and its top should
 784   // match new_top.
 785   assert(hr == NULL ||
 786          (hr->end() == new_end && hr->top() == new_top), "sanity");
 787 
 788   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 789   _summary_bytes_used += first_hr->used();
 790   _humongous_set.add(first_hr);
 791 
 792   return new_obj;
 793 }
 794 
 795 // If could fit into free regions w/o expansion, try.
 796 // Otherwise, if can expand, do so.
 797 // Otherwise, if using ex regions might help, try with ex given back.
 798 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 799   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 800 
 801   verify_region_sets_optional();
 802 
 803   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 804   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 805   uint x_num = expansion_regions();
 806   uint fs = _hrs.free_suffix();
 807   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 808   if (first == G1_NULL_HRS_INDEX) {
 809     // The only thing we can do now is attempt expansion.
 810     if (fs + x_num >= num_regions) {
 811       // If the number of regions we're trying to allocate for this
 812       // object is at most the number of regions in the free suffix,
 813       // then the call to humongous_obj_allocate_find_first() above
 814       // should have succeeded and we wouldn't be here.
 815       //
 816       // We should only be trying to expand when the free suffix is
 817       // not sufficient for the object _and_ we have some expansion
 818       // room available.
 819       assert(num_regions > fs, "earlier allocation should have succeeded");
 820 
 821       ergo_verbose1(ErgoHeapSizing,
 822                     "attempt heap expansion",
 823                     ergo_format_reason("humongous allocation request failed")
 824                     ergo_format_byte("allocation request"),
 825                     word_size * HeapWordSize);
 826       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 827         // Even though the heap was expanded, it might not have
 828         // reached the desired size. So, we cannot assume that the
 829         // allocation will succeed.
 830         first = humongous_obj_allocate_find_first(num_regions, word_size);
 831       }
 832     }
 833   }
 834 
 835   HeapWord* result = NULL;
 836   if (first != G1_NULL_HRS_INDEX) {
 837     result =
 838       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 839     assert(result != NULL, "it should always return a valid result");
 840 
 841     // A successful humongous object allocation changes the used space
 842     // information of the old generation so we need to recalculate the
 843     // sizes and update the jstat counters here.
 844     g1mm()->update_sizes();
 845   }
 846 
 847   verify_region_sets_optional();
 848 
 849   return result;
 850 }
 851 
 852 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 853   assert_heap_not_locked_and_not_at_safepoint();
 854   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 855 
 856   unsigned int dummy_gc_count_before;
 857   int dummy_gclocker_retry_count = 0;
 858   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 859 }
 860 
 861 HeapWord*
 862 G1CollectedHeap::mem_allocate(size_t word_size,
 863                               bool*  gc_overhead_limit_was_exceeded) {
 864   assert_heap_not_locked_and_not_at_safepoint();
 865 
 866   // Loop until the allocation is satisified, or unsatisfied after GC.
 867   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 868     unsigned int gc_count_before;
 869 
 870     HeapWord* result = NULL;
 871     if (!isHumongous(word_size)) {
 872       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 873     } else {
 874       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 875     }
 876     if (result != NULL) {
 877       return result;
 878     }
 879 
 880     // Create the garbage collection operation...
 881     VM_G1CollectForAllocation op(gc_count_before, word_size);
 882     // ...and get the VM thread to execute it.
 883     VMThread::execute(&op);
 884 
 885     if (op.prologue_succeeded() && op.pause_succeeded()) {
 886       // If the operation was successful we'll return the result even
 887       // if it is NULL. If the allocation attempt failed immediately
 888       // after a Full GC, it's unlikely we'll be able to allocate now.
 889       HeapWord* result = op.result();
 890       if (result != NULL && !isHumongous(word_size)) {
 891         // Allocations that take place on VM operations do not do any
 892         // card dirtying and we have to do it here. We only have to do
 893         // this for non-humongous allocations, though.
 894         dirty_young_block(result, word_size);
 895       }
 896       return result;
 897     } else {
 898       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 899         return NULL;
 900       }
 901       assert(op.result() == NULL,
 902              "the result should be NULL if the VM op did not succeed");
 903     }
 904 
 905     // Give a warning if we seem to be looping forever.
 906     if ((QueuedAllocationWarningCount > 0) &&
 907         (try_count % QueuedAllocationWarningCount == 0)) {
 908       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 909     }
 910   }
 911 
 912   ShouldNotReachHere();
 913   return NULL;
 914 }
 915 
 916 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 917                                            unsigned int *gc_count_before_ret,
 918                                            int* gclocker_retry_count_ret) {
 919   // Make sure you read the note in attempt_allocation_humongous().
 920 
 921   assert_heap_not_locked_and_not_at_safepoint();
 922   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 923          "be called for humongous allocation requests");
 924 
 925   // We should only get here after the first-level allocation attempt
 926   // (attempt_allocation()) failed to allocate.
 927 
 928   // We will loop until a) we manage to successfully perform the
 929   // allocation or b) we successfully schedule a collection which
 930   // fails to perform the allocation. b) is the only case when we'll
 931   // return NULL.
 932   HeapWord* result = NULL;
 933   for (int try_count = 1; /* we'll return */; try_count += 1) {
 934     bool should_try_gc;
 935     unsigned int gc_count_before;
 936 
 937     {
 938       MutexLockerEx x(Heap_lock);
 939 
 940       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 941                                                       false /* bot_updates */);
 942       if (result != NULL) {
 943         return result;
 944       }
 945 
 946       // If we reach here, attempt_allocation_locked() above failed to
 947       // allocate a new region. So the mutator alloc region should be NULL.
 948       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 949 
 950       if (GC_locker::is_active_and_needs_gc()) {
 951         if (g1_policy()->can_expand_young_list()) {
 952           // No need for an ergo verbose message here,
 953           // can_expand_young_list() does this when it returns true.
 954           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 955                                                       false /* bot_updates */);
 956           if (result != NULL) {
 957             return result;
 958           }
 959         }
 960         should_try_gc = false;
 961       } else {
 962         // The GCLocker may not be active but the GCLocker initiated
 963         // GC may not yet have been performed (GCLocker::needs_gc()
 964         // returns true). In this case we do not try this GC and
 965         // wait until the GCLocker initiated GC is performed, and
 966         // then retry the allocation.
 967         if (GC_locker::needs_gc()) {
 968           should_try_gc = false;
 969         } else {
 970           // Read the GC count while still holding the Heap_lock.
 971           gc_count_before = total_collections();
 972           should_try_gc = true;
 973         }
 974       }
 975     }
 976 
 977     if (should_try_gc) {
 978       bool succeeded;
 979       result = do_collection_pause(word_size, gc_count_before, &succeeded);
 980       if (result != NULL) {
 981         assert(succeeded, "only way to get back a non-NULL result");
 982         return result;
 983       }
 984 
 985       if (succeeded) {
 986         // If we get here we successfully scheduled a collection which
 987         // failed to allocate. No point in trying to allocate
 988         // further. We'll just return NULL.
 989         MutexLockerEx x(Heap_lock);
 990         *gc_count_before_ret = total_collections();
 991         return NULL;
 992       }
 993     } else {
 994       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 995         MutexLockerEx x(Heap_lock);
 996         *gc_count_before_ret = total_collections();
 997         return NULL;
 998       }
 999       // The GCLocker is either active or the GCLocker initiated
1000       // GC has not yet been performed. Stall until it is and
1001       // then retry the allocation.
1002       GC_locker::stall_until_clear();
1003       (*gclocker_retry_count_ret) += 1;
1004     }
1005 
1006     // We can reach here if we were unsuccessul in scheduling a
1007     // collection (because another thread beat us to it) or if we were
1008     // stalled due to the GC locker. In either can we should retry the
1009     // allocation attempt in case another thread successfully
1010     // performed a collection and reclaimed enough space. We do the
1011     // first attempt (without holding the Heap_lock) here and the
1012     // follow-on attempt will be at the start of the next loop
1013     // iteration (after taking the Heap_lock).
1014     result = _mutator_alloc_region.attempt_allocation(word_size,
1015                                                       false /* bot_updates */);
1016     if (result != NULL) {
1017       return result;
1018     }
1019 
1020     // Give a warning if we seem to be looping forever.
1021     if ((QueuedAllocationWarningCount > 0) &&
1022         (try_count % QueuedAllocationWarningCount == 0)) {
1023       warning("G1CollectedHeap::attempt_allocation_slow() "
1024               "retries %d times", try_count);
1025     }
1026   }
1027 
1028   ShouldNotReachHere();
1029   return NULL;
1030 }
1031 
1032 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1033                                           unsigned int * gc_count_before_ret,
1034                                           int* gclocker_retry_count_ret) {
1035   // The structure of this method has a lot of similarities to
1036   // attempt_allocation_slow(). The reason these two were not merged
1037   // into a single one is that such a method would require several "if
1038   // allocation is not humongous do this, otherwise do that"
1039   // conditional paths which would obscure its flow. In fact, an early
1040   // version of this code did use a unified method which was harder to
1041   // follow and, as a result, it had subtle bugs that were hard to
1042   // track down. So keeping these two methods separate allows each to
1043   // be more readable. It will be good to keep these two in sync as
1044   // much as possible.
1045 
1046   assert_heap_not_locked_and_not_at_safepoint();
1047   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1048          "should only be called for humongous allocations");
1049 
1050   // Humongous objects can exhaust the heap quickly, so we should check if we
1051   // need to start a marking cycle at each humongous object allocation. We do
1052   // the check before we do the actual allocation. The reason for doing it
1053   // before the allocation is that we avoid having to keep track of the newly
1054   // allocated memory while we do a GC.
1055   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1056                                            word_size)) {
1057     collect(GCCause::_g1_humongous_allocation);
1058   }
1059 
1060   // We will loop until a) we manage to successfully perform the
1061   // allocation or b) we successfully schedule a collection which
1062   // fails to perform the allocation. b) is the only case when we'll
1063   // return NULL.
1064   HeapWord* result = NULL;
1065   for (int try_count = 1; /* we'll return */; try_count += 1) {
1066     bool should_try_gc;
1067     unsigned int gc_count_before;
1068 
1069     {
1070       MutexLockerEx x(Heap_lock);
1071 
1072       // Given that humongous objects are not allocated in young
1073       // regions, we'll first try to do the allocation without doing a
1074       // collection hoping that there's enough space in the heap.
1075       result = humongous_obj_allocate(word_size);
1076       if (result != NULL) {
1077         return result;
1078       }
1079 
1080       if (GC_locker::is_active_and_needs_gc()) {
1081         should_try_gc = false;
1082       } else {
1083          // The GCLocker may not be active but the GCLocker initiated
1084         // GC may not yet have been performed (GCLocker::needs_gc()
1085         // returns true). In this case we do not try this GC and
1086         // wait until the GCLocker initiated GC is performed, and
1087         // then retry the allocation.
1088         if (GC_locker::needs_gc()) {
1089           should_try_gc = false;
1090         } else {
1091           // Read the GC count while still holding the Heap_lock.
1092           gc_count_before = total_collections();
1093           should_try_gc = true;
1094         }
1095       }
1096     }
1097 
1098     if (should_try_gc) {
1099       // If we failed to allocate the humongous object, we should try to
1100       // do a collection pause (if we're allowed) in case it reclaims
1101       // enough space for the allocation to succeed after the pause.
1102 
1103       bool succeeded;
1104       result = do_collection_pause(word_size, gc_count_before, &succeeded);
1105       if (result != NULL) {
1106         assert(succeeded, "only way to get back a non-NULL result");
1107         return result;
1108       }
1109 
1110       if (succeeded) {
1111         // If we get here we successfully scheduled a collection which
1112         // failed to allocate. No point in trying to allocate
1113         // further. We'll just return NULL.
1114         MutexLockerEx x(Heap_lock);
1115         *gc_count_before_ret = total_collections();
1116         return NULL;
1117       }
1118     } else {
1119       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1120         MutexLockerEx x(Heap_lock);
1121         *gc_count_before_ret = total_collections();
1122         return NULL;
1123       }
1124       // The GCLocker is either active or the GCLocker initiated
1125       // GC has not yet been performed. Stall until it is and
1126       // then retry the allocation.
1127       GC_locker::stall_until_clear();
1128       (*gclocker_retry_count_ret) += 1;
1129     }
1130 
1131     // We can reach here if we were unsuccessul in scheduling a
1132     // collection (because another thread beat us to it) or if we were
1133     // stalled due to the GC locker. In either can we should retry the
1134     // allocation attempt in case another thread successfully
1135     // performed a collection and reclaimed enough space.  Give a
1136     // warning if we seem to be looping forever.
1137 
1138     if ((QueuedAllocationWarningCount > 0) &&
1139         (try_count % QueuedAllocationWarningCount == 0)) {
1140       warning("G1CollectedHeap::attempt_allocation_humongous() "
1141               "retries %d times", try_count);
1142     }
1143   }
1144 
1145   ShouldNotReachHere();
1146   return NULL;
1147 }
1148 
1149 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1150                                        bool expect_null_mutator_alloc_region) {
1151   assert_at_safepoint(true /* should_be_vm_thread */);
1152   assert(_mutator_alloc_region.get() == NULL ||
1153                                              !expect_null_mutator_alloc_region,
1154          "the current alloc region was unexpectedly found to be non-NULL");
1155 
1156   if (!isHumongous(word_size)) {
1157     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1158                                                       false /* bot_updates */);
1159   } else {
1160     HeapWord* result = humongous_obj_allocate(word_size);
1161     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1162       g1_policy()->set_initiate_conc_mark_if_possible();
1163     }
1164     return result;
1165   }
1166 
1167   ShouldNotReachHere();
1168 }
1169 
1170 class PostMCRemSetClearClosure: public HeapRegionClosure {
1171   G1CollectedHeap* _g1h;
1172   ModRefBarrierSet* _mr_bs;
1173 public:
1174   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1175     _g1h(g1h), _mr_bs(mr_bs) { }
1176   bool doHeapRegion(HeapRegion* r) {
1177     if (r->continuesHumongous()) {
1178       return false;
1179     }
1180     _g1h->reset_gc_time_stamps(r);
1181     HeapRegionRemSet* hrrs = r->rem_set();
1182     if (hrrs != NULL) hrrs->clear();
1183     // You might think here that we could clear just the cards
1184     // corresponding to the used region.  But no: if we leave a dirty card
1185     // in a region we might allocate into, then it would prevent that card
1186     // from being enqueued, and cause it to be missed.
1187     // Re: the performance cost: we shouldn't be doing full GC anyway!
1188     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1189     return false;
1190   }
1191 };
1192 
1193 void G1CollectedHeap::clear_rsets_post_compaction() {
1194   PostMCRemSetClearClosure rs_clear(this, mr_bs());
1195   heap_region_iterate(&rs_clear);
1196 }
1197 
1198 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1199   G1CollectedHeap*   _g1h;
1200   UpdateRSOopClosure _cl;
1201   int                _worker_i;
1202 public:
1203   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1204     _cl(g1->g1_rem_set(), worker_i),
1205     _worker_i(worker_i),
1206     _g1h(g1)
1207   { }
1208 
1209   bool doHeapRegion(HeapRegion* r) {
1210     if (!r->continuesHumongous()) {
1211       _cl.set_from(r);
1212       r->oop_iterate(&_cl);
1213     }
1214     return false;
1215   }
1216 };
1217 
1218 class ParRebuildRSTask: public AbstractGangTask {
1219   G1CollectedHeap* _g1;
1220 public:
1221   ParRebuildRSTask(G1CollectedHeap* g1)
1222     : AbstractGangTask("ParRebuildRSTask"),
1223       _g1(g1)
1224   { }
1225 
1226   void work(uint worker_id) {
1227     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1228     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1229                                           _g1->workers()->active_workers(),
1230                                          HeapRegion::RebuildRSClaimValue);
1231   }
1232 };
1233 
1234 class PostCompactionPrinterClosure: public HeapRegionClosure {
1235 private:
1236   G1HRPrinter* _hr_printer;
1237 public:
1238   bool doHeapRegion(HeapRegion* hr) {
1239     assert(!hr->is_young(), "not expecting to find young regions");
1240     // We only generate output for non-empty regions.
1241     if (!hr->is_empty()) {
1242       if (!hr->isHumongous()) {
1243         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1244       } else if (hr->startsHumongous()) {
1245         if (hr->region_num() == 1) {
1246           // single humongous region
1247           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1248         } else {
1249           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1250         }
1251       } else {
1252         assert(hr->continuesHumongous(), "only way to get here");
1253         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1254       }
1255     }
1256     return false;
1257   }
1258 
1259   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1260     : _hr_printer(hr_printer) { }
1261 };
1262 
1263 void G1CollectedHeap::print_hrs_post_compaction() {
1264   PostCompactionPrinterClosure cl(hr_printer());
1265   heap_region_iterate(&cl);
1266 }
1267 
1268 double G1CollectedHeap::verify(bool guard, const char* msg) {
1269   double verify_time_ms = 0.0;
1270 
1271   if (guard && total_collections() >= VerifyGCStartAt) {
1272     double verify_start = os::elapsedTime();
1273     HandleMark hm;  // Discard invalid handles created during verification
1274     prepare_for_verify();
1275     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
1276     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
1277   }
1278 
1279   return verify_time_ms;
1280 }
1281 
1282 void G1CollectedHeap::verify_before_gc() {
1283   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
1284   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
1285 }
1286 
1287 void G1CollectedHeap::verify_after_gc() {
1288   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
1289   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
1290 }
1291 
1292 bool G1CollectedHeap::do_collection(bool explicit_gc,
1293                                     bool clear_all_soft_refs,
1294                                     size_t word_size) {
1295   assert_at_safepoint(true /* should_be_vm_thread */);
1296 
1297   if (GC_locker::check_active_before_gc()) {
1298     return false;
1299   }
1300 
1301   SvcGCMarker sgcm(SvcGCMarker::FULL);
1302   ResourceMark rm;
1303 
1304   print_heap_before_gc();
1305 
1306   size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1307 
1308   HRSPhaseSetter x(HRSPhaseFullGC);
1309   verify_region_sets_optional();
1310 
1311   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1312                            collector_policy()->should_clear_all_soft_refs();
1313 
1314   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1315 
1316   {
1317     IsGCActiveMark x;
1318 
1319     // Timing
1320     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1321     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1322     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1323 
1324     {
1325       TraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, gclog_or_tty);
1326       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1327       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1328 
1329       double start = os::elapsedTime();
1330       g1_policy()->record_full_collection_start();
1331 
1332       // Note: When we have a more flexible GC logging framework that
1333       // allows us to add optional attributes to a GC log record we
1334       // could consider timing and reporting how long we wait in the
1335       // following two methods.
1336       wait_while_free_regions_coming();
1337       // If we start the compaction before the CM threads finish
1338       // scanning the root regions we might trip them over as we'll
1339       // be moving objects / updating references. So let's wait until
1340       // they are done. By telling them to abort, they should complete
1341       // early.
1342       _cm->root_regions()->abort();
1343       _cm->root_regions()->wait_until_scan_finished();
1344       append_secondary_free_list_if_not_empty_with_lock();
1345 
1346       gc_prologue(true);
1347       increment_total_collections(true /* full gc */);
1348       increment_old_marking_cycles_started();
1349 
1350       assert(used() == recalculate_used(), "Should be equal");
1351 
1352       verify_before_gc();
1353 
1354       pre_full_gc_dump();
1355 
1356       COMPILER2_PRESENT(DerivedPointerTable::clear());
1357 
1358       // Disable discovery and empty the discovered lists
1359       // for the CM ref processor.
1360       ref_processor_cm()->disable_discovery();
1361       ref_processor_cm()->abandon_partial_discovery();
1362       ref_processor_cm()->verify_no_references_recorded();
1363 
1364       // Abandon current iterations of concurrent marking and concurrent
1365       // refinement, if any are in progress. We have to do this before
1366       // wait_until_scan_finished() below.
1367       concurrent_mark()->abort();
1368 
1369       // Make sure we'll choose a new allocation region afterwards.
1370       release_mutator_alloc_region();
1371       abandon_gc_alloc_regions();
1372       g1_rem_set()->cleanupHRRS();
1373 
1374       // We should call this after we retire any currently active alloc
1375       // regions so that all the ALLOC / RETIRE events are generated
1376       // before the start GC event.
1377       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1378 
1379       // We may have added regions to the current incremental collection
1380       // set between the last GC or pause and now. We need to clear the
1381       // incremental collection set and then start rebuilding it afresh
1382       // after this full GC.
1383       abandon_collection_set(g1_policy()->inc_cset_head());
1384       g1_policy()->clear_incremental_cset();
1385       g1_policy()->stop_incremental_cset_building();
1386 
1387       tear_down_region_sets(false /* free_list_only */);
1388       g1_policy()->set_gcs_are_young(true);
1389 
1390       // See the comments in g1CollectedHeap.hpp and
1391       // G1CollectedHeap::ref_processing_init() about
1392       // how reference processing currently works in G1.
1393 
1394       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1395       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1396 
1397       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1398       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1399 
1400       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1401       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1402 
1403       // Do collection work
1404       {
1405         HandleMark hm;  // Discard invalid handles created during gc
1406         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1407       }
1408 
1409       assert(free_regions() == 0, "we should not have added any free regions");
1410       rebuild_region_sets(false /* free_list_only */);
1411 
1412       // Enqueue any discovered reference objects that have
1413       // not been removed from the discovered lists.
1414       ref_processor_stw()->enqueue_discovered_references();
1415 
1416       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1417 
1418       MemoryService::track_memory_usage();
1419 
1420       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1421       ref_processor_stw()->verify_no_references_recorded();
1422 
1423       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1424       ClassLoaderDataGraph::purge();
1425     MetaspaceAux::verify_metrics();
1426 
1427       // Note: since we've just done a full GC, concurrent
1428       // marking is no longer active. Therefore we need not
1429       // re-enable reference discovery for the CM ref processor.
1430       // That will be done at the start of the next marking cycle.
1431       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1432       ref_processor_cm()->verify_no_references_recorded();
1433 
1434       reset_gc_time_stamp();
1435       // Since everything potentially moved, we will clear all remembered
1436       // sets, and clear all cards.  Later we will rebuild remebered
1437       // sets. We will also reset the GC time stamps of the regions.
1438       clear_rsets_post_compaction();
1439       check_gc_time_stamps();
1440 
1441       // Resize the heap if necessary.
1442       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1443 
1444       if (_hr_printer.is_active()) {
1445         // We should do this after we potentially resize the heap so
1446         // that all the COMMIT / UNCOMMIT events are generated before
1447         // the end GC event.
1448 
1449         print_hrs_post_compaction();
1450         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1451       }
1452 
1453       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1454       if (hot_card_cache->use_cache()) {
1455         hot_card_cache->reset_card_counts();
1456         hot_card_cache->reset_hot_cache();
1457       }
1458 
1459       // Rebuild remembered sets of all regions.
1460       if (G1CollectedHeap::use_parallel_gc_threads()) {
1461         uint n_workers =
1462           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1463                                                   workers()->active_workers(),
1464                                                   Threads::number_of_non_daemon_threads());
1465         assert(UseDynamicNumberOfGCThreads ||
1466                n_workers == workers()->total_workers(),
1467                "If not dynamic should be using all the  workers");
1468         workers()->set_active_workers(n_workers);
1469         // Set parallel threads in the heap (_n_par_threads) only
1470         // before a parallel phase and always reset it to 0 after
1471         // the phase so that the number of parallel threads does
1472         // no get carried forward to a serial phase where there
1473         // may be code that is "possibly_parallel".
1474         set_par_threads(n_workers);
1475 
1476         ParRebuildRSTask rebuild_rs_task(this);
1477         assert(check_heap_region_claim_values(
1478                HeapRegion::InitialClaimValue), "sanity check");
1479         assert(UseDynamicNumberOfGCThreads ||
1480                workers()->active_workers() == workers()->total_workers(),
1481                "Unless dynamic should use total workers");
1482         // Use the most recent number of  active workers
1483         assert(workers()->active_workers() > 0,
1484                "Active workers not properly set");
1485         set_par_threads(workers()->active_workers());
1486         workers()->run_task(&rebuild_rs_task);
1487         set_par_threads(0);
1488         assert(check_heap_region_claim_values(
1489                HeapRegion::RebuildRSClaimValue), "sanity check");
1490         reset_heap_region_claim_values();
1491       } else {
1492         RebuildRSOutOfRegionClosure rebuild_rs(this);
1493         heap_region_iterate(&rebuild_rs);
1494       }
1495 
1496       if (true) { // FIXME
1497         MetaspaceGC::compute_new_size();
1498       }
1499 
1500 #ifdef TRACESPINNING
1501       ParallelTaskTerminator::print_termination_counts();
1502 #endif
1503 
1504       // Discard all rset updates
1505       JavaThread::dirty_card_queue_set().abandon_logs();
1506       assert(!G1DeferredRSUpdate
1507              || (G1DeferredRSUpdate &&
1508                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1509 
1510       _young_list->reset_sampled_info();
1511       // At this point there should be no regions in the
1512       // entire heap tagged as young.
1513       assert(check_young_list_empty(true /* check_heap */),
1514              "young list should be empty at this point");
1515 
1516       // Update the number of full collections that have been completed.
1517       increment_old_marking_cycles_completed(false /* concurrent */);
1518 
1519       _hrs.verify_optional();
1520       verify_region_sets_optional();
1521 
1522       verify_after_gc();
1523 
1524       // Start a new incremental collection set for the next pause
1525       assert(g1_policy()->collection_set() == NULL, "must be");
1526       g1_policy()->start_incremental_cset_building();
1527 
1528       // Clear the _cset_fast_test bitmap in anticipation of adding
1529       // regions to the incremental collection set for the next
1530       // evacuation pause.
1531       clear_cset_fast_test();
1532 
1533       init_mutator_alloc_region();
1534 
1535       double end = os::elapsedTime();
1536       g1_policy()->record_full_collection_end();
1537 
1538       if (G1Log::fine()) {
1539         g1_policy()->print_heap_transition();
1540       }
1541 
1542       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1543       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1544       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1545       // before any GC notifications are raised.
1546       g1mm()->update_sizes();
1547 
1548       gc_epilogue(true);
1549     }
1550 
1551     if (G1Log::finer()) {
1552       g1_policy()->print_detailed_heap_transition(true /* full */);
1553     }
1554 
1555     print_heap_after_gc();
1556 
1557     post_full_gc_dump();
1558   }
1559 
1560   return true;
1561 }
1562 
1563 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1564   // do_collection() will return whether it succeeded in performing
1565   // the GC. Currently, there is no facility on the
1566   // do_full_collection() API to notify the caller than the collection
1567   // did not succeed (e.g., because it was locked out by the GC
1568   // locker). So, right now, we'll ignore the return value.
1569   bool dummy = do_collection(true,                /* explicit_gc */
1570                              clear_all_soft_refs,
1571                              0                    /* word_size */);
1572 }
1573 
1574 // This code is mostly copied from TenuredGeneration.
1575 void
1576 G1CollectedHeap::
1577 resize_if_necessary_after_full_collection(size_t word_size) {
1578   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1579 
1580   // Include the current allocation, if any, and bytes that will be
1581   // pre-allocated to support collections, as "used".
1582   const size_t used_after_gc = used();
1583   const size_t capacity_after_gc = capacity();
1584   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1585 
1586   // This is enforced in arguments.cpp.
1587   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1588          "otherwise the code below doesn't make sense");
1589 
1590   // We don't have floating point command-line arguments
1591   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1592   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1593   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1594   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1595 
1596   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1597   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1598 
1599   // We have to be careful here as these two calculations can overflow
1600   // 32-bit size_t's.
1601   double used_after_gc_d = (double) used_after_gc;
1602   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1603   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1604 
1605   // Let's make sure that they are both under the max heap size, which
1606   // by default will make them fit into a size_t.
1607   double desired_capacity_upper_bound = (double) max_heap_size;
1608   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1609                                     desired_capacity_upper_bound);
1610   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1611                                     desired_capacity_upper_bound);
1612 
1613   // We can now safely turn them into size_t's.
1614   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1615   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1616 
1617   // This assert only makes sense here, before we adjust them
1618   // with respect to the min and max heap size.
1619   assert(minimum_desired_capacity <= maximum_desired_capacity,
1620          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1621                  "maximum_desired_capacity = "SIZE_FORMAT,
1622                  minimum_desired_capacity, maximum_desired_capacity));
1623 
1624   // Should not be greater than the heap max size. No need to adjust
1625   // it with respect to the heap min size as it's a lower bound (i.e.,
1626   // we'll try to make the capacity larger than it, not smaller).
1627   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1628   // Should not be less than the heap min size. No need to adjust it
1629   // with respect to the heap max size as it's an upper bound (i.e.,
1630   // we'll try to make the capacity smaller than it, not greater).
1631   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1632 
1633   if (capacity_after_gc < minimum_desired_capacity) {
1634     // Don't expand unless it's significant
1635     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1636     ergo_verbose4(ErgoHeapSizing,
1637                   "attempt heap expansion",
1638                   ergo_format_reason("capacity lower than "
1639                                      "min desired capacity after Full GC")
1640                   ergo_format_byte("capacity")
1641                   ergo_format_byte("occupancy")
1642                   ergo_format_byte_perc("min desired capacity"),
1643                   capacity_after_gc, used_after_gc,
1644                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1645     expand(expand_bytes);
1646 
1647     // No expansion, now see if we want to shrink
1648   } else if (capacity_after_gc > maximum_desired_capacity) {
1649     // Capacity too large, compute shrinking size
1650     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1651     ergo_verbose4(ErgoHeapSizing,
1652                   "attempt heap shrinking",
1653                   ergo_format_reason("capacity higher than "
1654                                      "max desired capacity after Full GC")
1655                   ergo_format_byte("capacity")
1656                   ergo_format_byte("occupancy")
1657                   ergo_format_byte_perc("max desired capacity"),
1658                   capacity_after_gc, used_after_gc,
1659                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1660     shrink(shrink_bytes);
1661   }
1662 }
1663 
1664 
1665 HeapWord*
1666 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1667                                            bool* succeeded) {
1668   assert_at_safepoint(true /* should_be_vm_thread */);
1669 
1670   *succeeded = true;
1671   // Let's attempt the allocation first.
1672   HeapWord* result =
1673     attempt_allocation_at_safepoint(word_size,
1674                                  false /* expect_null_mutator_alloc_region */);
1675   if (result != NULL) {
1676     assert(*succeeded, "sanity");
1677     return result;
1678   }
1679 
1680   // In a G1 heap, we're supposed to keep allocation from failing by
1681   // incremental pauses.  Therefore, at least for now, we'll favor
1682   // expansion over collection.  (This might change in the future if we can
1683   // do something smarter than full collection to satisfy a failed alloc.)
1684   result = expand_and_allocate(word_size);
1685   if (result != NULL) {
1686     assert(*succeeded, "sanity");
1687     return result;
1688   }
1689 
1690   // Expansion didn't work, we'll try to do a Full GC.
1691   bool gc_succeeded = do_collection(false, /* explicit_gc */
1692                                     false, /* clear_all_soft_refs */
1693                                     word_size);
1694   if (!gc_succeeded) {
1695     *succeeded = false;
1696     return NULL;
1697   }
1698 
1699   // Retry the allocation
1700   result = attempt_allocation_at_safepoint(word_size,
1701                                   true /* expect_null_mutator_alloc_region */);
1702   if (result != NULL) {
1703     assert(*succeeded, "sanity");
1704     return result;
1705   }
1706 
1707   // Then, try a Full GC that will collect all soft references.
1708   gc_succeeded = do_collection(false, /* explicit_gc */
1709                                true,  /* clear_all_soft_refs */
1710                                word_size);
1711   if (!gc_succeeded) {
1712     *succeeded = false;
1713     return NULL;
1714   }
1715 
1716   // Retry the allocation once more
1717   result = attempt_allocation_at_safepoint(word_size,
1718                                   true /* expect_null_mutator_alloc_region */);
1719   if (result != NULL) {
1720     assert(*succeeded, "sanity");
1721     return result;
1722   }
1723 
1724   assert(!collector_policy()->should_clear_all_soft_refs(),
1725          "Flag should have been handled and cleared prior to this point");
1726 
1727   // What else?  We might try synchronous finalization later.  If the total
1728   // space available is large enough for the allocation, then a more
1729   // complete compaction phase than we've tried so far might be
1730   // appropriate.
1731   assert(*succeeded, "sanity");
1732   return NULL;
1733 }
1734 
1735 // Attempting to expand the heap sufficiently
1736 // to support an allocation of the given "word_size".  If
1737 // successful, perform the allocation and return the address of the
1738 // allocated block, or else "NULL".
1739 
1740 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1741   assert_at_safepoint(true /* should_be_vm_thread */);
1742 
1743   verify_region_sets_optional();
1744 
1745   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1746   ergo_verbose1(ErgoHeapSizing,
1747                 "attempt heap expansion",
1748                 ergo_format_reason("allocation request failed")
1749                 ergo_format_byte("allocation request"),
1750                 word_size * HeapWordSize);
1751   if (expand(expand_bytes)) {
1752     _hrs.verify_optional();
1753     verify_region_sets_optional();
1754     return attempt_allocation_at_safepoint(word_size,
1755                                  false /* expect_null_mutator_alloc_region */);
1756   }
1757   return NULL;
1758 }
1759 
1760 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1761                                              HeapWord* new_end) {
1762   assert(old_end != new_end, "don't call this otherwise");
1763   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1764 
1765   // Update the committed mem region.
1766   _g1_committed.set_end(new_end);
1767   // Tell the card table about the update.
1768   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1769   // Tell the BOT about the update.
1770   _bot_shared->resize(_g1_committed.word_size());
1771   // Tell the hot card cache about the update
1772   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1773 }
1774 
1775 bool G1CollectedHeap::expand(size_t expand_bytes) {
1776   size_t old_mem_size = _g1_storage.committed_size();
1777   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1778   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1779                                        HeapRegion::GrainBytes);
1780   ergo_verbose2(ErgoHeapSizing,
1781                 "expand the heap",
1782                 ergo_format_byte("requested expansion amount")
1783                 ergo_format_byte("attempted expansion amount"),
1784                 expand_bytes, aligned_expand_bytes);
1785 
1786   // First commit the memory.
1787   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1788   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1789   if (successful) {
1790     // Then propagate this update to the necessary data structures.
1791     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1792     update_committed_space(old_end, new_end);
1793 
1794     FreeRegionList expansion_list("Local Expansion List");
1795     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1796     assert(mr.start() == old_end, "post-condition");
1797     // mr might be a smaller region than what was requested if
1798     // expand_by() was unable to allocate the HeapRegion instances
1799     assert(mr.end() <= new_end, "post-condition");
1800 
1801     size_t actual_expand_bytes = mr.byte_size();
1802     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1803     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1804            "post-condition");
1805     if (actual_expand_bytes < aligned_expand_bytes) {
1806       // We could not expand _hrs to the desired size. In this case we
1807       // need to shrink the committed space accordingly.
1808       assert(mr.end() < new_end, "invariant");
1809 
1810       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1811       // First uncommit the memory.
1812       _g1_storage.shrink_by(diff_bytes);
1813       // Then propagate this update to the necessary data structures.
1814       update_committed_space(new_end, mr.end());
1815     }
1816     _free_list.add_as_tail(&expansion_list);
1817 
1818     if (_hr_printer.is_active()) {
1819       HeapWord* curr = mr.start();
1820       while (curr < mr.end()) {
1821         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1822         _hr_printer.commit(curr, curr_end);
1823         curr = curr_end;
1824       }
1825       assert(curr == mr.end(), "post-condition");
1826     }
1827     g1_policy()->record_new_heap_size(n_regions());
1828   } else {
1829     ergo_verbose0(ErgoHeapSizing,
1830                   "did not expand the heap",
1831                   ergo_format_reason("heap expansion operation failed"));
1832     // The expansion of the virtual storage space was unsuccessful.
1833     // Let's see if it was because we ran out of swap.
1834     if (G1ExitOnExpansionFailure &&
1835         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1836       // We had head room...
1837       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1838     }
1839   }
1840   return successful;
1841 }
1842 
1843 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1844   size_t old_mem_size = _g1_storage.committed_size();
1845   size_t aligned_shrink_bytes =
1846     ReservedSpace::page_align_size_down(shrink_bytes);
1847   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1848                                          HeapRegion::GrainBytes);
1849   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1850 
1851   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1852   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1853   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1854 
1855   ergo_verbose3(ErgoHeapSizing,
1856                 "shrink the heap",
1857                 ergo_format_byte("requested shrinking amount")
1858                 ergo_format_byte("aligned shrinking amount")
1859                 ergo_format_byte("attempted shrinking amount"),
1860                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1861   if (num_regions_removed > 0) {
1862     _g1_storage.shrink_by(shrunk_bytes);
1863     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1864 
1865     if (_hr_printer.is_active()) {
1866       HeapWord* curr = old_end;
1867       while (curr > new_end) {
1868         HeapWord* curr_end = curr;
1869         curr -= HeapRegion::GrainWords;
1870         _hr_printer.uncommit(curr, curr_end);
1871       }
1872     }
1873 
1874     _expansion_regions += num_regions_removed;
1875     update_committed_space(old_end, new_end);
1876     HeapRegionRemSet::shrink_heap(n_regions());
1877     g1_policy()->record_new_heap_size(n_regions());
1878   } else {
1879     ergo_verbose0(ErgoHeapSizing,
1880                   "did not shrink the heap",
1881                   ergo_format_reason("heap shrinking operation failed"));
1882   }
1883 }
1884 
1885 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1886   verify_region_sets_optional();
1887 
1888   // We should only reach here at the end of a Full GC which means we
1889   // should not not be holding to any GC alloc regions. The method
1890   // below will make sure of that and do any remaining clean up.
1891   abandon_gc_alloc_regions();
1892 
1893   // Instead of tearing down / rebuilding the free lists here, we
1894   // could instead use the remove_all_pending() method on free_list to
1895   // remove only the ones that we need to remove.
1896   tear_down_region_sets(true /* free_list_only */);
1897   shrink_helper(shrink_bytes);
1898   rebuild_region_sets(true /* free_list_only */);
1899 
1900   _hrs.verify_optional();
1901   verify_region_sets_optional();
1902 }
1903 
1904 // Public methods.
1905 
1906 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1907 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1908 #endif // _MSC_VER
1909 
1910 
1911 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1912   SharedHeap(policy_),
1913   _g1_policy(policy_),
1914   _dirty_card_queue_set(false),
1915   _into_cset_dirty_card_queue_set(false),
1916   _is_alive_closure_cm(this),
1917   _is_alive_closure_stw(this),
1918   _ref_processor_cm(NULL),
1919   _ref_processor_stw(NULL),
1920   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1921   _bot_shared(NULL),
1922   _evac_failure_scan_stack(NULL) ,
1923   _mark_in_progress(false),
1924   _cg1r(NULL), _summary_bytes_used(0),
1925   _g1mm(NULL),
1926   _refine_cte_cl(NULL),
1927   _full_collection(false),
1928   _free_list("Master Free List"),
1929   _secondary_free_list("Secondary Free List"),
1930   _old_set("Old Set"),
1931   _humongous_set("Master Humongous Set"),
1932   _free_regions_coming(false),
1933   _young_list(new YoungList(this)),
1934   _gc_time_stamp(0),
1935   _retained_old_gc_alloc_region(NULL),
1936   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1937   _old_plab_stats(OldPLABSize, PLABWeight),
1938   _expand_heap_after_alloc_failure(true),
1939   _surviving_young_words(NULL),
1940   _old_marking_cycles_started(0),
1941   _old_marking_cycles_completed(0),
1942   _in_cset_fast_test(NULL),
1943   _in_cset_fast_test_base(NULL),
1944   _dirty_cards_region_list(NULL),
1945   _worker_cset_start_region(NULL),
1946   _worker_cset_start_region_time_stamp(NULL) {
1947   _g1h = this; // To catch bugs.
1948   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1949     vm_exit_during_initialization("Failed necessary allocation.");
1950   }
1951 
1952   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1953 
1954   int n_queues = MAX2((int)ParallelGCThreads, 1);
1955   _task_queues = new RefToScanQueueSet(n_queues);
1956 
1957   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1958   assert(n_rem_sets > 0, "Invariant.");
1959 
1960   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1961   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1962 
1963   for (int i = 0; i < n_queues; i++) {
1964     RefToScanQueue* q = new RefToScanQueue();
1965     q->initialize();
1966     _task_queues->register_queue(i, q);
1967   }
1968 
1969   clear_cset_start_regions();
1970 
1971   // Initialize the G1EvacuationFailureALot counters and flags.
1972   NOT_PRODUCT(reset_evacuation_should_fail();)
1973 
1974   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1975 }
1976 
1977 jint G1CollectedHeap::initialize() {
1978   CollectedHeap::pre_initialize();
1979   os::enable_vtime();
1980 
1981   G1Log::init();
1982 
1983   // Necessary to satisfy locking discipline assertions.
1984 
1985   MutexLocker x(Heap_lock);
1986 
1987   // We have to initialize the printer before committing the heap, as
1988   // it will be used then.
1989   _hr_printer.set_active(G1PrintHeapRegions);
1990 
1991   // While there are no constraints in the GC code that HeapWordSize
1992   // be any particular value, there are multiple other areas in the
1993   // system which believe this to be true (e.g. oop->object_size in some
1994   // cases incorrectly returns the size in wordSize units rather than
1995   // HeapWordSize).
1996   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1997 
1998   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1999   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2000 
2001   // Ensure that the sizes are properly aligned.
2002   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2003   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2004 
2005   _cg1r = new ConcurrentG1Refine(this);
2006 
2007   // Reserve the maximum.
2008 
2009   // When compressed oops are enabled, the preferred heap base
2010   // is calculated by subtracting the requested size from the
2011   // 32Gb boundary and using the result as the base address for
2012   // heap reservation. If the requested size is not aligned to
2013   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2014   // into the ReservedHeapSpace constructor) then the actual
2015   // base of the reserved heap may end up differing from the
2016   // address that was requested (i.e. the preferred heap base).
2017   // If this happens then we could end up using a non-optimal
2018   // compressed oops mode.
2019 
2020   // Since max_byte_size is aligned to the size of a heap region (checked
2021   // above).
2022   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2023 
2024   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2025                                                  HeapRegion::GrainBytes);
2026 
2027   // It is important to do this in a way such that concurrent readers can't
2028   // temporarily think somethings in the heap.  (I've actually seen this
2029   // happen in asserts: DLD.)
2030   _reserved.set_word_size(0);
2031   _reserved.set_start((HeapWord*)heap_rs.base());
2032   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2033 
2034   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2035 
2036   // Create the gen rem set (and barrier set) for the entire reserved region.
2037   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2038   set_barrier_set(rem_set()->bs());
2039   if (barrier_set()->is_a(BarrierSet::ModRef)) {
2040     _mr_bs = (ModRefBarrierSet*)_barrier_set;
2041   } else {
2042     vm_exit_during_initialization("G1 requires a mod ref bs.");
2043     return JNI_ENOMEM;
2044   }
2045 
2046   // Also create a G1 rem set.
2047   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2048     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2049   } else {
2050     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2051     return JNI_ENOMEM;
2052   }
2053 
2054   // Carve out the G1 part of the heap.
2055 
2056   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2057   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2058                            g1_rs.size()/HeapWordSize);
2059 
2060   _g1_storage.initialize(g1_rs, 0);
2061   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2062   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2063                   (HeapWord*) _g1_reserved.end(),
2064                   _expansion_regions);
2065 
2066   // Do later initialization work for concurrent refinement.
2067   _cg1r->init();
2068 
2069   // 6843694 - ensure that the maximum region index can fit
2070   // in the remembered set structures.
2071   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2072   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2073 
2074   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2075   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2076   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2077             "too many cards per region");
2078 
2079   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2080 
2081   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2082                                              heap_word_size(init_byte_size));
2083 
2084   _g1h = this;
2085 
2086   _in_cset_fast_test_length = max_regions();
2087   _in_cset_fast_test_base =
2088                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2089 
2090   // We're biasing _in_cset_fast_test to avoid subtracting the
2091   // beginning of the heap every time we want to index; basically
2092   // it's the same with what we do with the card table.
2093   _in_cset_fast_test = _in_cset_fast_test_base -
2094                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2095 
2096   // Clear the _cset_fast_test bitmap in anticipation of adding
2097   // regions to the incremental collection set for the first
2098   // evacuation pause.
2099   clear_cset_fast_test();
2100 
2101   // Create the ConcurrentMark data structure and thread.
2102   // (Must do this late, so that "max_regions" is defined.)
2103   _cm = new ConcurrentMark(this, heap_rs);
2104   if (_cm == NULL || !_cm->completed_initialization()) {
2105     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2106     return JNI_ENOMEM;
2107   }
2108   _cmThread = _cm->cmThread();
2109 
2110   // Initialize the from_card cache structure of HeapRegionRemSet.
2111   HeapRegionRemSet::init_heap(max_regions());
2112 
2113   // Now expand into the initial heap size.
2114   if (!expand(init_byte_size)) {
2115     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2116     return JNI_ENOMEM;
2117   }
2118 
2119   // Perform any initialization actions delegated to the policy.
2120   g1_policy()->init();
2121 
2122   _refine_cte_cl =
2123     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2124                                     g1_rem_set(),
2125                                     concurrent_g1_refine());
2126   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2127 
2128   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2129                                                SATB_Q_FL_lock,
2130                                                G1SATBProcessCompletedThreshold,
2131                                                Shared_SATB_Q_lock);
2132 
2133   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2134                                                 DirtyCardQ_FL_lock,
2135                                                 concurrent_g1_refine()->yellow_zone(),
2136                                                 concurrent_g1_refine()->red_zone(),
2137                                                 Shared_DirtyCardQ_lock);
2138 
2139   if (G1DeferredRSUpdate) {
2140     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2141                                       DirtyCardQ_FL_lock,
2142                                       -1, // never trigger processing
2143                                       -1, // no limit on length
2144                                       Shared_DirtyCardQ_lock,
2145                                       &JavaThread::dirty_card_queue_set());
2146   }
2147 
2148   // Initialize the card queue set used to hold cards containing
2149   // references into the collection set.
2150   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2151                                              DirtyCardQ_FL_lock,
2152                                              -1, // never trigger processing
2153                                              -1, // no limit on length
2154                                              Shared_DirtyCardQ_lock,
2155                                              &JavaThread::dirty_card_queue_set());
2156 
2157   // In case we're keeping closure specialization stats, initialize those
2158   // counts and that mechanism.
2159   SpecializationStats::clear();
2160 
2161   // Here we allocate the dummy full region that is required by the
2162   // G1AllocRegion class. If we don't pass an address in the reserved
2163   // space here, lots of asserts fire.
2164 
2165   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2166                                              _g1_reserved.start());
2167   // We'll re-use the same region whether the alloc region will
2168   // require BOT updates or not and, if it doesn't, then a non-young
2169   // region will complain that it cannot support allocations without
2170   // BOT updates. So we'll tag the dummy region as young to avoid that.
2171   dummy_region->set_young();
2172   // Make sure it's full.
2173   dummy_region->set_top(dummy_region->end());
2174   G1AllocRegion::setup(this, dummy_region);
2175 
2176   init_mutator_alloc_region();
2177 
2178   // Do create of the monitoring and management support so that
2179   // values in the heap have been properly initialized.
2180   _g1mm = new G1MonitoringSupport(this);
2181 
2182   return JNI_OK;
2183 }
2184 
2185 void G1CollectedHeap::ref_processing_init() {
2186   // Reference processing in G1 currently works as follows:
2187   //
2188   // * There are two reference processor instances. One is
2189   //   used to record and process discovered references
2190   //   during concurrent marking; the other is used to
2191   //   record and process references during STW pauses
2192   //   (both full and incremental).
2193   // * Both ref processors need to 'span' the entire heap as
2194   //   the regions in the collection set may be dotted around.
2195   //
2196   // * For the concurrent marking ref processor:
2197   //   * Reference discovery is enabled at initial marking.
2198   //   * Reference discovery is disabled and the discovered
2199   //     references processed etc during remarking.
2200   //   * Reference discovery is MT (see below).
2201   //   * Reference discovery requires a barrier (see below).
2202   //   * Reference processing may or may not be MT
2203   //     (depending on the value of ParallelRefProcEnabled
2204   //     and ParallelGCThreads).
2205   //   * A full GC disables reference discovery by the CM
2206   //     ref processor and abandons any entries on it's
2207   //     discovered lists.
2208   //
2209   // * For the STW processor:
2210   //   * Non MT discovery is enabled at the start of a full GC.
2211   //   * Processing and enqueueing during a full GC is non-MT.
2212   //   * During a full GC, references are processed after marking.
2213   //
2214   //   * Discovery (may or may not be MT) is enabled at the start
2215   //     of an incremental evacuation pause.
2216   //   * References are processed near the end of a STW evacuation pause.
2217   //   * For both types of GC:
2218   //     * Discovery is atomic - i.e. not concurrent.
2219   //     * Reference discovery will not need a barrier.
2220 
2221   SharedHeap::ref_processing_init();
2222   MemRegion mr = reserved_region();
2223 
2224   // Concurrent Mark ref processor
2225   _ref_processor_cm =
2226     new ReferenceProcessor(mr,    // span
2227                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2228                                 // mt processing
2229                            (int) ParallelGCThreads,
2230                                 // degree of mt processing
2231                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2232                                 // mt discovery
2233                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2234                                 // degree of mt discovery
2235                            false,
2236                                 // Reference discovery is not atomic
2237                            &_is_alive_closure_cm,
2238                                 // is alive closure
2239                                 // (for efficiency/performance)
2240                            true);
2241                                 // Setting next fields of discovered
2242                                 // lists requires a barrier.
2243 
2244   // STW ref processor
2245   _ref_processor_stw =
2246     new ReferenceProcessor(mr,    // span
2247                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2248                                 // mt processing
2249                            MAX2((int)ParallelGCThreads, 1),
2250                                 // degree of mt processing
2251                            (ParallelGCThreads > 1),
2252                                 // mt discovery
2253                            MAX2((int)ParallelGCThreads, 1),
2254                                 // degree of mt discovery
2255                            true,
2256                                 // Reference discovery is atomic
2257                            &_is_alive_closure_stw,
2258                                 // is alive closure
2259                                 // (for efficiency/performance)
2260                            false);
2261                                 // Setting next fields of discovered
2262                                 // lists requires a barrier.
2263 }
2264 
2265 size_t G1CollectedHeap::capacity() const {
2266   return _g1_committed.byte_size();
2267 }
2268 
2269 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2270   assert(!hr->continuesHumongous(), "pre-condition");
2271   hr->reset_gc_time_stamp();
2272   if (hr->startsHumongous()) {
2273     uint first_index = hr->hrs_index() + 1;
2274     uint last_index = hr->last_hc_index();
2275     for (uint i = first_index; i < last_index; i += 1) {
2276       HeapRegion* chr = region_at(i);
2277       assert(chr->continuesHumongous(), "sanity");
2278       chr->reset_gc_time_stamp();
2279     }
2280   }
2281 }
2282 
2283 #ifndef PRODUCT
2284 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2285 private:
2286   unsigned _gc_time_stamp;
2287   bool _failures;
2288 
2289 public:
2290   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2291     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2292 
2293   virtual bool doHeapRegion(HeapRegion* hr) {
2294     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2295     if (_gc_time_stamp != region_gc_time_stamp) {
2296       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2297                              "expected %d", HR_FORMAT_PARAMS(hr),
2298                              region_gc_time_stamp, _gc_time_stamp);
2299       _failures = true;
2300     }
2301     return false;
2302   }
2303 
2304   bool failures() { return _failures; }
2305 };
2306 
2307 void G1CollectedHeap::check_gc_time_stamps() {
2308   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2309   heap_region_iterate(&cl);
2310   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2311 }
2312 #endif // PRODUCT
2313 
2314 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2315                                                  DirtyCardQueue* into_cset_dcq,
2316                                                  bool concurrent,
2317                                                  int worker_i) {
2318   // Clean cards in the hot card cache
2319   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2320   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2321 
2322   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2323   int n_completed_buffers = 0;
2324   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2325     n_completed_buffers++;
2326   }
2327   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2328   dcqs.clear_n_completed_buffers();
2329   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2330 }
2331 
2332 
2333 // Computes the sum of the storage used by the various regions.
2334 
2335 size_t G1CollectedHeap::used() const {
2336   assert(Heap_lock->owner() != NULL,
2337          "Should be owned on this thread's behalf.");
2338   size_t result = _summary_bytes_used;
2339   // Read only once in case it is set to NULL concurrently
2340   HeapRegion* hr = _mutator_alloc_region.get();
2341   if (hr != NULL)
2342     result += hr->used();
2343   return result;
2344 }
2345 
2346 size_t G1CollectedHeap::used_unlocked() const {
2347   size_t result = _summary_bytes_used;
2348   return result;
2349 }
2350 
2351 class SumUsedClosure: public HeapRegionClosure {
2352   size_t _used;
2353 public:
2354   SumUsedClosure() : _used(0) {}
2355   bool doHeapRegion(HeapRegion* r) {
2356     if (!r->continuesHumongous()) {
2357       _used += r->used();
2358     }
2359     return false;
2360   }
2361   size_t result() { return _used; }
2362 };
2363 
2364 size_t G1CollectedHeap::recalculate_used() const {
2365   SumUsedClosure blk;
2366   heap_region_iterate(&blk);
2367   return blk.result();
2368 }
2369 
2370 size_t G1CollectedHeap::unsafe_max_alloc() {
2371   if (free_regions() > 0) return HeapRegion::GrainBytes;
2372   // otherwise, is there space in the current allocation region?
2373 
2374   // We need to store the current allocation region in a local variable
2375   // here. The problem is that this method doesn't take any locks and
2376   // there may be other threads which overwrite the current allocation
2377   // region field. attempt_allocation(), for example, sets it to NULL
2378   // and this can happen *after* the NULL check here but before the call
2379   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2380   // to be a problem in the optimized build, since the two loads of the
2381   // current allocation region field are optimized away.
2382   HeapRegion* hr = _mutator_alloc_region.get();
2383   if (hr == NULL) {
2384     return 0;
2385   }
2386   return hr->free();
2387 }
2388 
2389 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2390   switch (cause) {
2391     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2392     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2393     case GCCause::_g1_humongous_allocation: return true;
2394     default:                                return false;
2395   }
2396 }
2397 
2398 #ifndef PRODUCT
2399 void G1CollectedHeap::allocate_dummy_regions() {
2400   // Let's fill up most of the region
2401   size_t word_size = HeapRegion::GrainWords - 1024;
2402   // And as a result the region we'll allocate will be humongous.
2403   guarantee(isHumongous(word_size), "sanity");
2404 
2405   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2406     // Let's use the existing mechanism for the allocation
2407     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2408     if (dummy_obj != NULL) {
2409       MemRegion mr(dummy_obj, word_size);
2410       CollectedHeap::fill_with_object(mr);
2411     } else {
2412       // If we can't allocate once, we probably cannot allocate
2413       // again. Let's get out of the loop.
2414       break;
2415     }
2416   }
2417 }
2418 #endif // !PRODUCT
2419 
2420 void G1CollectedHeap::increment_old_marking_cycles_started() {
2421   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2422     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2423     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2424     _old_marking_cycles_started, _old_marking_cycles_completed));
2425 
2426   _old_marking_cycles_started++;
2427 }
2428 
2429 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2430   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2431 
2432   // We assume that if concurrent == true, then the caller is a
2433   // concurrent thread that was joined the Suspendible Thread
2434   // Set. If there's ever a cheap way to check this, we should add an
2435   // assert here.
2436 
2437   // Given that this method is called at the end of a Full GC or of a
2438   // concurrent cycle, and those can be nested (i.e., a Full GC can
2439   // interrupt a concurrent cycle), the number of full collections
2440   // completed should be either one (in the case where there was no
2441   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2442   // behind the number of full collections started.
2443 
2444   // This is the case for the inner caller, i.e. a Full GC.
2445   assert(concurrent ||
2446          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2447          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2448          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2449                  "is inconsistent with _old_marking_cycles_completed = %u",
2450                  _old_marking_cycles_started, _old_marking_cycles_completed));
2451 
2452   // This is the case for the outer caller, i.e. the concurrent cycle.
2453   assert(!concurrent ||
2454          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2455          err_msg("for outer caller (concurrent cycle): "
2456                  "_old_marking_cycles_started = %u "
2457                  "is inconsistent with _old_marking_cycles_completed = %u",
2458                  _old_marking_cycles_started, _old_marking_cycles_completed));
2459 
2460   _old_marking_cycles_completed += 1;
2461 
2462   // We need to clear the "in_progress" flag in the CM thread before
2463   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2464   // is set) so that if a waiter requests another System.gc() it doesn't
2465   // incorrectly see that a marking cyle is still in progress.
2466   if (concurrent) {
2467     _cmThread->clear_in_progress();
2468   }
2469 
2470   // This notify_all() will ensure that a thread that called
2471   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2472   // and it's waiting for a full GC to finish will be woken up. It is
2473   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2474   FullGCCount_lock->notify_all();
2475 }
2476 
2477 void G1CollectedHeap::collect(GCCause::Cause cause) {
2478   assert_heap_not_locked();
2479 
2480   unsigned int gc_count_before;
2481   unsigned int old_marking_count_before;
2482   bool retry_gc;
2483 
2484   do {
2485     retry_gc = false;
2486 
2487     {
2488       MutexLocker ml(Heap_lock);
2489 
2490       // Read the GC count while holding the Heap_lock
2491       gc_count_before = total_collections();
2492       old_marking_count_before = _old_marking_cycles_started;
2493     }
2494 
2495     if (should_do_concurrent_full_gc(cause)) {
2496       // Schedule an initial-mark evacuation pause that will start a
2497       // concurrent cycle. We're setting word_size to 0 which means that
2498       // we are not requesting a post-GC allocation.
2499       VM_G1IncCollectionPause op(gc_count_before,
2500                                  0,     /* word_size */
2501                                  true,  /* should_initiate_conc_mark */
2502                                  g1_policy()->max_pause_time_ms(),
2503                                  cause);
2504 
2505       VMThread::execute(&op);
2506       if (!op.pause_succeeded()) {
2507         if (old_marking_count_before == _old_marking_cycles_started) {
2508           retry_gc = op.should_retry_gc();
2509         } else {
2510           // A Full GC happened while we were trying to schedule the
2511           // initial-mark GC. No point in starting a new cycle given
2512           // that the whole heap was collected anyway.
2513         }
2514 
2515         if (retry_gc) {
2516           if (GC_locker::is_active_and_needs_gc()) {
2517             GC_locker::stall_until_clear();
2518           }
2519         }
2520       }
2521     } else {
2522       if (cause == GCCause::_gc_locker
2523           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2524 
2525         // Schedule a standard evacuation pause. We're setting word_size
2526         // to 0 which means that we are not requesting a post-GC allocation.
2527         VM_G1IncCollectionPause op(gc_count_before,
2528                                    0,     /* word_size */
2529                                    false, /* should_initiate_conc_mark */
2530                                    g1_policy()->max_pause_time_ms(),
2531                                    cause);
2532         VMThread::execute(&op);
2533       } else {
2534         // Schedule a Full GC.
2535         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2536         VMThread::execute(&op);
2537       }
2538     }
2539   } while (retry_gc);
2540 }
2541 
2542 bool G1CollectedHeap::is_in(const void* p) const {
2543   if (_g1_committed.contains(p)) {
2544     // Given that we know that p is in the committed space,
2545     // heap_region_containing_raw() should successfully
2546     // return the containing region.
2547     HeapRegion* hr = heap_region_containing_raw(p);
2548     return hr->is_in(p);
2549   } else {
2550     return false;
2551   }
2552 }
2553 
2554 // Iteration functions.
2555 
2556 // Iterates an OopClosure over all ref-containing fields of objects
2557 // within a HeapRegion.
2558 
2559 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2560   MemRegion _mr;
2561   ExtendedOopClosure* _cl;
2562 public:
2563   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2564     : _mr(mr), _cl(cl) {}
2565   bool doHeapRegion(HeapRegion* r) {
2566     if (!r->continuesHumongous()) {
2567       r->oop_iterate(_cl);
2568     }
2569     return false;
2570   }
2571 };
2572 
2573 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2574   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2575   heap_region_iterate(&blk);
2576 }
2577 
2578 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2579   IterateOopClosureRegionClosure blk(mr, cl);
2580   heap_region_iterate(&blk);
2581 }
2582 
2583 // Iterates an ObjectClosure over all objects within a HeapRegion.
2584 
2585 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2586   ObjectClosure* _cl;
2587 public:
2588   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2589   bool doHeapRegion(HeapRegion* r) {
2590     if (! r->continuesHumongous()) {
2591       r->object_iterate(_cl);
2592     }
2593     return false;
2594   }
2595 };
2596 
2597 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2598   IterateObjectClosureRegionClosure blk(cl);
2599   heap_region_iterate(&blk);
2600 }
2601 
2602 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2603   // FIXME: is this right?
2604   guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2605 }
2606 
2607 // Calls a SpaceClosure on a HeapRegion.
2608 
2609 class SpaceClosureRegionClosure: public HeapRegionClosure {
2610   SpaceClosure* _cl;
2611 public:
2612   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2613   bool doHeapRegion(HeapRegion* r) {
2614     _cl->do_space(r);
2615     return false;
2616   }
2617 };
2618 
2619 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2620   SpaceClosureRegionClosure blk(cl);
2621   heap_region_iterate(&blk);
2622 }
2623 
2624 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2625   _hrs.iterate(cl);
2626 }
2627 
2628 void
2629 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2630                                                  uint worker_id,
2631                                                  uint no_of_par_workers,
2632                                                  jint claim_value) {
2633   const uint regions = n_regions();
2634   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2635                              no_of_par_workers :
2636                              1);
2637   assert(UseDynamicNumberOfGCThreads ||
2638          no_of_par_workers == workers()->total_workers(),
2639          "Non dynamic should use fixed number of workers");
2640   // try to spread out the starting points of the workers
2641   const HeapRegion* start_hr =
2642                         start_region_for_worker(worker_id, no_of_par_workers);
2643   const uint start_index = start_hr->hrs_index();
2644 
2645   // each worker will actually look at all regions
2646   for (uint count = 0; count < regions; ++count) {
2647     const uint index = (start_index + count) % regions;
2648     assert(0 <= index && index < regions, "sanity");
2649     HeapRegion* r = region_at(index);
2650     // we'll ignore "continues humongous" regions (we'll process them
2651     // when we come across their corresponding "start humongous"
2652     // region) and regions already claimed
2653     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2654       continue;
2655     }
2656     // OK, try to claim it
2657     if (r->claimHeapRegion(claim_value)) {
2658       // success!
2659       assert(!r->continuesHumongous(), "sanity");
2660       if (r->startsHumongous()) {
2661         // If the region is "starts humongous" we'll iterate over its
2662         // "continues humongous" first; in fact we'll do them
2663         // first. The order is important. In on case, calling the
2664         // closure on the "starts humongous" region might de-allocate
2665         // and clear all its "continues humongous" regions and, as a
2666         // result, we might end up processing them twice. So, we'll do
2667         // them first (notice: most closures will ignore them anyway) and
2668         // then we'll do the "starts humongous" region.
2669         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2670           HeapRegion* chr = region_at(ch_index);
2671 
2672           // if the region has already been claimed or it's not
2673           // "continues humongous" we're done
2674           if (chr->claim_value() == claim_value ||
2675               !chr->continuesHumongous()) {
2676             break;
2677           }
2678 
2679           // Noone should have claimed it directly. We can given
2680           // that we claimed its "starts humongous" region.
2681           assert(chr->claim_value() != claim_value, "sanity");
2682           assert(chr->humongous_start_region() == r, "sanity");
2683 
2684           if (chr->claimHeapRegion(claim_value)) {
2685             // we should always be able to claim it; noone else should
2686             // be trying to claim this region
2687 
2688             bool res2 = cl->doHeapRegion(chr);
2689             assert(!res2, "Should not abort");
2690 
2691             // Right now, this holds (i.e., no closure that actually
2692             // does something with "continues humongous" regions
2693             // clears them). We might have to weaken it in the future,
2694             // but let's leave these two asserts here for extra safety.
2695             assert(chr->continuesHumongous(), "should still be the case");
2696             assert(chr->humongous_start_region() == r, "sanity");
2697           } else {
2698             guarantee(false, "we should not reach here");
2699           }
2700         }
2701       }
2702 
2703       assert(!r->continuesHumongous(), "sanity");
2704       bool res = cl->doHeapRegion(r);
2705       assert(!res, "Should not abort");
2706     }
2707   }
2708 }
2709 
2710 class ResetClaimValuesClosure: public HeapRegionClosure {
2711 public:
2712   bool doHeapRegion(HeapRegion* r) {
2713     r->set_claim_value(HeapRegion::InitialClaimValue);
2714     return false;
2715   }
2716 };
2717 
2718 void G1CollectedHeap::reset_heap_region_claim_values() {
2719   ResetClaimValuesClosure blk;
2720   heap_region_iterate(&blk);
2721 }
2722 
2723 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2724   ResetClaimValuesClosure blk;
2725   collection_set_iterate(&blk);
2726 }
2727 
2728 #ifdef ASSERT
2729 // This checks whether all regions in the heap have the correct claim
2730 // value. I also piggy-backed on this a check to ensure that the
2731 // humongous_start_region() information on "continues humongous"
2732 // regions is correct.
2733 
2734 class CheckClaimValuesClosure : public HeapRegionClosure {
2735 private:
2736   jint _claim_value;
2737   uint _failures;
2738   HeapRegion* _sh_region;
2739 
2740 public:
2741   CheckClaimValuesClosure(jint claim_value) :
2742     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2743   bool doHeapRegion(HeapRegion* r) {
2744     if (r->claim_value() != _claim_value) {
2745       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2746                              "claim value = %d, should be %d",
2747                              HR_FORMAT_PARAMS(r),
2748                              r->claim_value(), _claim_value);
2749       ++_failures;
2750     }
2751     if (!r->isHumongous()) {
2752       _sh_region = NULL;
2753     } else if (r->startsHumongous()) {
2754       _sh_region = r;
2755     } else if (r->continuesHumongous()) {
2756       if (r->humongous_start_region() != _sh_region) {
2757         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2758                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2759                                HR_FORMAT_PARAMS(r),
2760                                r->humongous_start_region(),
2761                                _sh_region);
2762         ++_failures;
2763       }
2764     }
2765     return false;
2766   }
2767   uint failures() { return _failures; }
2768 };
2769 
2770 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2771   CheckClaimValuesClosure cl(claim_value);
2772   heap_region_iterate(&cl);
2773   return cl.failures() == 0;
2774 }
2775 
2776 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2777 private:
2778   jint _claim_value;
2779   uint _failures;
2780 
2781 public:
2782   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2783     _claim_value(claim_value), _failures(0) { }
2784 
2785   uint failures() { return _failures; }
2786 
2787   bool doHeapRegion(HeapRegion* hr) {
2788     assert(hr->in_collection_set(), "how?");
2789     assert(!hr->isHumongous(), "H-region in CSet");
2790     if (hr->claim_value() != _claim_value) {
2791       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2792                              "claim value = %d, should be %d",
2793                              HR_FORMAT_PARAMS(hr),
2794                              hr->claim_value(), _claim_value);
2795       _failures += 1;
2796     }
2797     return false;
2798   }
2799 };
2800 
2801 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2802   CheckClaimValuesInCSetHRClosure cl(claim_value);
2803   collection_set_iterate(&cl);
2804   return cl.failures() == 0;
2805 }
2806 #endif // ASSERT
2807 
2808 // Clear the cached CSet starting regions and (more importantly)
2809 // the time stamps. Called when we reset the GC time stamp.
2810 void G1CollectedHeap::clear_cset_start_regions() {
2811   assert(_worker_cset_start_region != NULL, "sanity");
2812   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2813 
2814   int n_queues = MAX2((int)ParallelGCThreads, 1);
2815   for (int i = 0; i < n_queues; i++) {
2816     _worker_cset_start_region[i] = NULL;
2817     _worker_cset_start_region_time_stamp[i] = 0;
2818   }
2819 }
2820 
2821 // Given the id of a worker, obtain or calculate a suitable
2822 // starting region for iterating over the current collection set.
2823 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2824   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2825 
2826   HeapRegion* result = NULL;
2827   unsigned gc_time_stamp = get_gc_time_stamp();
2828 
2829   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2830     // Cached starting region for current worker was set
2831     // during the current pause - so it's valid.
2832     // Note: the cached starting heap region may be NULL
2833     // (when the collection set is empty).
2834     result = _worker_cset_start_region[worker_i];
2835     assert(result == NULL || result->in_collection_set(), "sanity");
2836     return result;
2837   }
2838 
2839   // The cached entry was not valid so let's calculate
2840   // a suitable starting heap region for this worker.
2841 
2842   // We want the parallel threads to start their collection
2843   // set iteration at different collection set regions to
2844   // avoid contention.
2845   // If we have:
2846   //          n collection set regions
2847   //          p threads
2848   // Then thread t will start at region floor ((t * n) / p)
2849 
2850   result = g1_policy()->collection_set();
2851   if (G1CollectedHeap::use_parallel_gc_threads()) {
2852     uint cs_size = g1_policy()->cset_region_length();
2853     uint active_workers = workers()->active_workers();
2854     assert(UseDynamicNumberOfGCThreads ||
2855              active_workers == workers()->total_workers(),
2856              "Unless dynamic should use total workers");
2857 
2858     uint end_ind   = (cs_size * worker_i) / active_workers;
2859     uint start_ind = 0;
2860 
2861     if (worker_i > 0 &&
2862         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2863       // Previous workers starting region is valid
2864       // so let's iterate from there
2865       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2866       result = _worker_cset_start_region[worker_i - 1];
2867     }
2868 
2869     for (uint i = start_ind; i < end_ind; i++) {
2870       result = result->next_in_collection_set();
2871     }
2872   }
2873 
2874   // Note: the calculated starting heap region may be NULL
2875   // (when the collection set is empty).
2876   assert(result == NULL || result->in_collection_set(), "sanity");
2877   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2878          "should be updated only once per pause");
2879   _worker_cset_start_region[worker_i] = result;
2880   OrderAccess::storestore();
2881   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2882   return result;
2883 }
2884 
2885 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2886                                                      uint no_of_par_workers) {
2887   uint worker_num =
2888            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2889   assert(UseDynamicNumberOfGCThreads ||
2890          no_of_par_workers == workers()->total_workers(),
2891          "Non dynamic should use fixed number of workers");
2892   const uint start_index = n_regions() * worker_i / worker_num;
2893   return region_at(start_index);
2894 }
2895 
2896 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2897   HeapRegion* r = g1_policy()->collection_set();
2898   while (r != NULL) {
2899     HeapRegion* next = r->next_in_collection_set();
2900     if (cl->doHeapRegion(r)) {
2901       cl->incomplete();
2902       return;
2903     }
2904     r = next;
2905   }
2906 }
2907 
2908 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2909                                                   HeapRegionClosure *cl) {
2910   if (r == NULL) {
2911     // The CSet is empty so there's nothing to do.
2912     return;
2913   }
2914 
2915   assert(r->in_collection_set(),
2916          "Start region must be a member of the collection set.");
2917   HeapRegion* cur = r;
2918   while (cur != NULL) {
2919     HeapRegion* next = cur->next_in_collection_set();
2920     if (cl->doHeapRegion(cur) && false) {
2921       cl->incomplete();
2922       return;
2923     }
2924     cur = next;
2925   }
2926   cur = g1_policy()->collection_set();
2927   while (cur != r) {
2928     HeapRegion* next = cur->next_in_collection_set();
2929     if (cl->doHeapRegion(cur) && false) {
2930       cl->incomplete();
2931       return;
2932     }
2933     cur = next;
2934   }
2935 }
2936 
2937 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2938   return n_regions() > 0 ? region_at(0) : NULL;
2939 }
2940 
2941 
2942 Space* G1CollectedHeap::space_containing(const void* addr) const {
2943   Space* res = heap_region_containing(addr);
2944   return res;
2945 }
2946 
2947 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2948   Space* sp = space_containing(addr);
2949   if (sp != NULL) {
2950     return sp->block_start(addr);
2951   }
2952   return NULL;
2953 }
2954 
2955 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2956   Space* sp = space_containing(addr);
2957   assert(sp != NULL, "block_size of address outside of heap");
2958   return sp->block_size(addr);
2959 }
2960 
2961 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2962   Space* sp = space_containing(addr);
2963   return sp->block_is_obj(addr);
2964 }
2965 
2966 bool G1CollectedHeap::supports_tlab_allocation() const {
2967   return true;
2968 }
2969 
2970 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2971   return HeapRegion::GrainBytes;
2972 }
2973 
2974 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2975   // Return the remaining space in the cur alloc region, but not less than
2976   // the min TLAB size.
2977 
2978   // Also, this value can be at most the humongous object threshold,
2979   // since we can't allow tlabs to grow big enough to accomodate
2980   // humongous objects.
2981 
2982   HeapRegion* hr = _mutator_alloc_region.get();
2983   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2984   if (hr == NULL) {
2985     return max_tlab_size;
2986   } else {
2987     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2988   }
2989 }
2990 
2991 size_t G1CollectedHeap::max_capacity() const {
2992   return _g1_reserved.byte_size();
2993 }
2994 
2995 jlong G1CollectedHeap::millis_since_last_gc() {
2996   // assert(false, "NYI");
2997   return 0;
2998 }
2999 
3000 void G1CollectedHeap::prepare_for_verify() {
3001   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3002     ensure_parsability(false);
3003   }
3004   g1_rem_set()->prepare_for_verify();
3005 }
3006 
3007 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3008                                               VerifyOption vo) {
3009   switch (vo) {
3010   case VerifyOption_G1UsePrevMarking:
3011     return hr->obj_allocated_since_prev_marking(obj);
3012   case VerifyOption_G1UseNextMarking:
3013     return hr->obj_allocated_since_next_marking(obj);
3014   case VerifyOption_G1UseMarkWord:
3015     return false;
3016   default:
3017     ShouldNotReachHere();
3018   }
3019   return false; // keep some compilers happy
3020 }
3021 
3022 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3023   switch (vo) {
3024   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3025   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3026   case VerifyOption_G1UseMarkWord:    return NULL;
3027   default:                            ShouldNotReachHere();
3028   }
3029   return NULL; // keep some compilers happy
3030 }
3031 
3032 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3033   switch (vo) {
3034   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3035   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3036   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3037   default:                            ShouldNotReachHere();
3038   }
3039   return false; // keep some compilers happy
3040 }
3041 
3042 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3043   switch (vo) {
3044   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3045   case VerifyOption_G1UseNextMarking: return "NTAMS";
3046   case VerifyOption_G1UseMarkWord:    return "NONE";
3047   default:                            ShouldNotReachHere();
3048   }
3049   return NULL; // keep some compilers happy
3050 }
3051 
3052 class VerifyLivenessOopClosure: public OopClosure {
3053   G1CollectedHeap* _g1h;
3054   VerifyOption _vo;
3055 public:
3056   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3057     _g1h(g1h), _vo(vo)
3058   { }
3059   void do_oop(narrowOop *p) { do_oop_work(p); }
3060   void do_oop(      oop *p) { do_oop_work(p); }
3061 
3062   template <class T> void do_oop_work(T *p) {
3063     oop obj = oopDesc::load_decode_heap_oop(p);
3064     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3065               "Dead object referenced by a not dead object");
3066   }
3067 };
3068 
3069 class VerifyObjsInRegionClosure: public ObjectClosure {
3070 private:
3071   G1CollectedHeap* _g1h;
3072   size_t _live_bytes;
3073   HeapRegion *_hr;
3074   VerifyOption _vo;
3075 public:
3076   // _vo == UsePrevMarking -> use "prev" marking information,
3077   // _vo == UseNextMarking -> use "next" marking information,
3078   // _vo == UseMarkWord    -> use mark word from object header.
3079   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3080     : _live_bytes(0), _hr(hr), _vo(vo) {
3081     _g1h = G1CollectedHeap::heap();
3082   }
3083   void do_object(oop o) {
3084     VerifyLivenessOopClosure isLive(_g1h, _vo);
3085     assert(o != NULL, "Huh?");
3086     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3087       // If the object is alive according to the mark word,
3088       // then verify that the marking information agrees.
3089       // Note we can't verify the contra-positive of the
3090       // above: if the object is dead (according to the mark
3091       // word), it may not be marked, or may have been marked
3092       // but has since became dead, or may have been allocated
3093       // since the last marking.
3094       if (_vo == VerifyOption_G1UseMarkWord) {
3095         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3096       }
3097 
3098       o->oop_iterate_no_header(&isLive);
3099       if (!_hr->obj_allocated_since_prev_marking(o)) {
3100         size_t obj_size = o->size();    // Make sure we don't overflow
3101         _live_bytes += (obj_size * HeapWordSize);
3102       }
3103     }
3104   }
3105   size_t live_bytes() { return _live_bytes; }
3106 };
3107 
3108 class PrintObjsInRegionClosure : public ObjectClosure {
3109   HeapRegion *_hr;
3110   G1CollectedHeap *_g1;
3111 public:
3112   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3113     _g1 = G1CollectedHeap::heap();
3114   };
3115 
3116   void do_object(oop o) {
3117     if (o != NULL) {
3118       HeapWord *start = (HeapWord *) o;
3119       size_t word_sz = o->size();
3120       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3121                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3122                           (void*) o, word_sz,
3123                           _g1->isMarkedPrev(o),
3124                           _g1->isMarkedNext(o),
3125                           _hr->obj_allocated_since_prev_marking(o));
3126       HeapWord *end = start + word_sz;
3127       HeapWord *cur;
3128       int *val;
3129       for (cur = start; cur < end; cur++) {
3130         val = (int *) cur;
3131         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3132       }
3133     }
3134   }
3135 };
3136 
3137 class VerifyRegionClosure: public HeapRegionClosure {
3138 private:
3139   bool             _par;
3140   VerifyOption     _vo;
3141   bool             _failures;
3142 public:
3143   // _vo == UsePrevMarking -> use "prev" marking information,
3144   // _vo == UseNextMarking -> use "next" marking information,
3145   // _vo == UseMarkWord    -> use mark word from object header.
3146   VerifyRegionClosure(bool par, VerifyOption vo)
3147     : _par(par),
3148       _vo(vo),
3149       _failures(false) {}
3150 
3151   bool failures() {
3152     return _failures;
3153   }
3154 
3155   bool doHeapRegion(HeapRegion* r) {
3156     if (!r->continuesHumongous()) {
3157       bool failures = false;
3158       r->verify(_vo, &failures);
3159       if (failures) {
3160         _failures = true;
3161       } else {
3162         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3163         r->object_iterate(&not_dead_yet_cl);
3164         if (_vo != VerifyOption_G1UseNextMarking) {
3165           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3166             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3167                                    "max_live_bytes "SIZE_FORMAT" "
3168                                    "< calculated "SIZE_FORMAT,
3169                                    r->bottom(), r->end(),
3170                                    r->max_live_bytes(),
3171                                  not_dead_yet_cl.live_bytes());
3172             _failures = true;
3173           }
3174         } else {
3175           // When vo == UseNextMarking we cannot currently do a sanity
3176           // check on the live bytes as the calculation has not been
3177           // finalized yet.
3178         }
3179       }
3180     }
3181     return false; // stop the region iteration if we hit a failure
3182   }
3183 };
3184 
3185 class YoungRefCounterClosure : public OopClosure {
3186   G1CollectedHeap* _g1h;
3187   int              _count;
3188  public:
3189   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3190   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3191   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3192 
3193   int count() { return _count; }
3194   void reset_count() { _count = 0; };
3195 };
3196 
3197 class VerifyKlassClosure: public KlassClosure {
3198   YoungRefCounterClosure _young_ref_counter_closure;
3199   OopClosure *_oop_closure;
3200  public:
3201   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3202   void do_klass(Klass* k) {
3203     k->oops_do(_oop_closure);
3204 
3205     _young_ref_counter_closure.reset_count();
3206     k->oops_do(&_young_ref_counter_closure);
3207     if (_young_ref_counter_closure.count() > 0) {
3208       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3209     }
3210   }
3211 };
3212 
3213 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3214 //       pass it as the perm_blk to SharedHeap::process_strong_roots.
3215 //       When process_strong_roots stop calling perm_blk->younger_refs_iterate
3216 //       we can change this closure to extend the simpler OopClosure.
3217 class VerifyRootsClosure: public OopsInGenClosure {
3218 private:
3219   G1CollectedHeap* _g1h;
3220   VerifyOption     _vo;
3221   bool             _failures;
3222 public:
3223   // _vo == UsePrevMarking -> use "prev" marking information,
3224   // _vo == UseNextMarking -> use "next" marking information,
3225   // _vo == UseMarkWord    -> use mark word from object header.
3226   VerifyRootsClosure(VerifyOption vo) :
3227     _g1h(G1CollectedHeap::heap()),
3228     _vo(vo),
3229     _failures(false) { }
3230 
3231   bool failures() { return _failures; }
3232 
3233   template <class T> void do_oop_nv(T* p) {
3234     T heap_oop = oopDesc::load_heap_oop(p);
3235     if (!oopDesc::is_null(heap_oop)) {
3236       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3237       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3238         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3239                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3240         if (_vo == VerifyOption_G1UseMarkWord) {
3241           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3242         }
3243         obj->print_on(gclog_or_tty);
3244         _failures = true;
3245       }
3246     }
3247   }
3248 
3249   void do_oop(oop* p)       { do_oop_nv(p); }
3250   void do_oop(narrowOop* p) { do_oop_nv(p); }
3251 };
3252 
3253 // This is the task used for parallel heap verification.
3254 
3255 class G1ParVerifyTask: public AbstractGangTask {
3256 private:
3257   G1CollectedHeap* _g1h;
3258   VerifyOption     _vo;
3259   bool             _failures;
3260 
3261 public:
3262   // _vo == UsePrevMarking -> use "prev" marking information,
3263   // _vo == UseNextMarking -> use "next" marking information,
3264   // _vo == UseMarkWord    -> use mark word from object header.
3265   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3266     AbstractGangTask("Parallel verify task"),
3267     _g1h(g1h),
3268     _vo(vo),
3269     _failures(false) { }
3270 
3271   bool failures() {
3272     return _failures;
3273   }
3274 
3275   void work(uint worker_id) {
3276     HandleMark hm;
3277     VerifyRegionClosure blk(true, _vo);
3278     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3279                                           _g1h->workers()->active_workers(),
3280                                           HeapRegion::ParVerifyClaimValue);
3281     if (blk.failures()) {
3282       _failures = true;
3283     }
3284   }
3285 };
3286 
3287 void G1CollectedHeap::verify(bool silent) {
3288   verify(silent, VerifyOption_G1UsePrevMarking);
3289 }
3290 
3291 void G1CollectedHeap::verify(bool silent,
3292                              VerifyOption vo) {
3293   if (SafepointSynchronize::is_at_safepoint()) {
3294     if (!silent) { gclog_or_tty->print("Roots "); }
3295     VerifyRootsClosure rootsCl(vo);
3296 
3297     assert(Thread::current()->is_VM_thread(),
3298            "Expected to be executed serially by the VM thread at this point");
3299 
3300     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3301     VerifyKlassClosure klassCl(this, &rootsCl);
3302 
3303     // We apply the relevant closures to all the oops in the
3304     // system dictionary, the string table and the code cache.
3305     const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3306 
3307     // Need cleared claim bits for the strong roots processing
3308     ClassLoaderDataGraph::clear_claimed_marks();
3309 
3310     process_strong_roots(true,      // activate StrongRootsScope
3311                          false,     // we set "is scavenging" to false,
3312                                     // so we don't reset the dirty cards.
3313                          ScanningOption(so),  // roots scanning options
3314                          &rootsCl,
3315                          &blobsCl,
3316                          &klassCl
3317                          );
3318 
3319     bool failures = rootsCl.failures();
3320 
3321     if (vo != VerifyOption_G1UseMarkWord) {
3322       // If we're verifying during a full GC then the region sets
3323       // will have been torn down at the start of the GC. Therefore
3324       // verifying the region sets will fail. So we only verify
3325       // the region sets when not in a full GC.
3326       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3327       verify_region_sets();
3328     }
3329 
3330     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3331     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3332       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3333              "sanity check");
3334 
3335       G1ParVerifyTask task(this, vo);
3336       assert(UseDynamicNumberOfGCThreads ||
3337         workers()->active_workers() == workers()->total_workers(),
3338         "If not dynamic should be using all the workers");
3339       int n_workers = workers()->active_workers();
3340       set_par_threads(n_workers);
3341       workers()->run_task(&task);
3342       set_par_threads(0);
3343       if (task.failures()) {
3344         failures = true;
3345       }
3346 
3347       // Checks that the expected amount of parallel work was done.
3348       // The implication is that n_workers is > 0.
3349       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3350              "sanity check");
3351 
3352       reset_heap_region_claim_values();
3353 
3354       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3355              "sanity check");
3356     } else {
3357       VerifyRegionClosure blk(false, vo);
3358       heap_region_iterate(&blk);
3359       if (blk.failures()) {
3360         failures = true;
3361       }
3362     }
3363     if (!silent) gclog_or_tty->print("RemSet ");
3364     rem_set()->verify();
3365 
3366     if (failures) {
3367       gclog_or_tty->print_cr("Heap:");
3368       // It helps to have the per-region information in the output to
3369       // help us track down what went wrong. This is why we call
3370       // print_extended_on() instead of print_on().
3371       print_extended_on(gclog_or_tty);
3372       gclog_or_tty->print_cr("");
3373 #ifndef PRODUCT
3374       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3375         concurrent_mark()->print_reachable("at-verification-failure",
3376                                            vo, false /* all */);
3377       }
3378 #endif
3379       gclog_or_tty->flush();
3380     }
3381     guarantee(!failures, "there should not have been any failures");
3382   } else {
3383     if (!silent)
3384       gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3385   }
3386 }
3387 
3388 class PrintRegionClosure: public HeapRegionClosure {
3389   outputStream* _st;
3390 public:
3391   PrintRegionClosure(outputStream* st) : _st(st) {}
3392   bool doHeapRegion(HeapRegion* r) {
3393     r->print_on(_st);
3394     return false;
3395   }
3396 };
3397 
3398 void G1CollectedHeap::print_on(outputStream* st) const {
3399   st->print(" %-20s", "garbage-first heap");
3400   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3401             capacity()/K, used_unlocked()/K);
3402   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3403             _g1_storage.low_boundary(),
3404             _g1_storage.high(),
3405             _g1_storage.high_boundary());
3406   st->cr();
3407   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3408   uint young_regions = _young_list->length();
3409   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3410             (size_t) young_regions * HeapRegion::GrainBytes / K);
3411   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3412   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3413             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3414   st->cr();
3415   MetaspaceAux::print_on(st);
3416 }
3417 
3418 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3419   print_on(st);
3420 
3421   // Print the per-region information.
3422   st->cr();
3423   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3424                "HS=humongous(starts), HC=humongous(continues), "
3425                "CS=collection set, F=free, TS=gc time stamp, "
3426                "PTAMS=previous top-at-mark-start, "
3427                "NTAMS=next top-at-mark-start)");
3428   PrintRegionClosure blk(st);
3429   heap_region_iterate(&blk);
3430 }
3431 
3432 void G1CollectedHeap::print_on_error(outputStream* st) const {
3433   this->CollectedHeap::print_on_error(st);
3434 
3435   if (_cm != NULL) {
3436     st->cr();
3437     _cm->print_on_error(st);
3438   }
3439 }
3440 
3441 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3442   if (G1CollectedHeap::use_parallel_gc_threads()) {
3443     workers()->print_worker_threads_on(st);
3444   }
3445   _cmThread->print_on(st);
3446   st->cr();
3447   _cm->print_worker_threads_on(st);
3448   _cg1r->print_worker_threads_on(st);
3449 }
3450 
3451 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3452   if (G1CollectedHeap::use_parallel_gc_threads()) {
3453     workers()->threads_do(tc);
3454   }
3455   tc->do_thread(_cmThread);
3456   _cg1r->threads_do(tc);
3457 }
3458 
3459 void G1CollectedHeap::print_tracing_info() const {
3460   // We'll overload this to mean "trace GC pause statistics."
3461   if (TraceGen0Time || TraceGen1Time) {
3462     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3463     // to that.
3464     g1_policy()->print_tracing_info();
3465   }
3466   if (G1SummarizeRSetStats) {
3467     g1_rem_set()->print_summary_info();
3468   }
3469   if (G1SummarizeConcMark) {
3470     concurrent_mark()->print_summary_info();
3471   }
3472   g1_policy()->print_yg_surv_rate_info();
3473   SpecializationStats::print();
3474 }
3475 
3476 #ifndef PRODUCT
3477 // Helpful for debugging RSet issues.
3478 
3479 class PrintRSetsClosure : public HeapRegionClosure {
3480 private:
3481   const char* _msg;
3482   size_t _occupied_sum;
3483 
3484 public:
3485   bool doHeapRegion(HeapRegion* r) {
3486     HeapRegionRemSet* hrrs = r->rem_set();
3487     size_t occupied = hrrs->occupied();
3488     _occupied_sum += occupied;
3489 
3490     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3491                            HR_FORMAT_PARAMS(r));
3492     if (occupied == 0) {
3493       gclog_or_tty->print_cr("  RSet is empty");
3494     } else {
3495       hrrs->print();
3496     }
3497     gclog_or_tty->print_cr("----------");
3498     return false;
3499   }
3500 
3501   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3502     gclog_or_tty->cr();
3503     gclog_or_tty->print_cr("========================================");
3504     gclog_or_tty->print_cr(msg);
3505     gclog_or_tty->cr();
3506   }
3507 
3508   ~PrintRSetsClosure() {
3509     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3510     gclog_or_tty->print_cr("========================================");
3511     gclog_or_tty->cr();
3512   }
3513 };
3514 
3515 void G1CollectedHeap::print_cset_rsets() {
3516   PrintRSetsClosure cl("Printing CSet RSets");
3517   collection_set_iterate(&cl);
3518 }
3519 
3520 void G1CollectedHeap::print_all_rsets() {
3521   PrintRSetsClosure cl("Printing All RSets");;
3522   heap_region_iterate(&cl);
3523 }
3524 #endif // PRODUCT
3525 
3526 G1CollectedHeap* G1CollectedHeap::heap() {
3527   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3528          "not a garbage-first heap");
3529   return _g1h;
3530 }
3531 
3532 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3533   // always_do_update_barrier = false;
3534   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3535   // Call allocation profiler
3536   AllocationProfiler::iterate_since_last_gc();
3537   // Fill TLAB's and such
3538   ensure_parsability(true);
3539 }
3540 
3541 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3542   // FIXME: what is this about?
3543   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3544   // is set.
3545   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3546                         "derived pointer present"));
3547   // always_do_update_barrier = true;
3548 
3549   // We have just completed a GC. Update the soft reference
3550   // policy with the new heap occupancy
3551   Universe::update_heap_info_at_gc();
3552 }
3553 
3554 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3555                                                unsigned int gc_count_before,
3556                                                bool* succeeded) {
3557   assert_heap_not_locked_and_not_at_safepoint();
3558   g1_policy()->record_stop_world_start();
3559   VM_G1IncCollectionPause op(gc_count_before,
3560                              word_size,
3561                              false, /* should_initiate_conc_mark */
3562                              g1_policy()->max_pause_time_ms(),
3563                              GCCause::_g1_inc_collection_pause);
3564   VMThread::execute(&op);
3565 
3566   HeapWord* result = op.result();
3567   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3568   assert(result == NULL || ret_succeeded,
3569          "the result should be NULL if the VM did not succeed");
3570   *succeeded = ret_succeeded;
3571 
3572   assert_heap_not_locked();
3573   return result;
3574 }
3575 
3576 void
3577 G1CollectedHeap::doConcurrentMark() {
3578   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3579   if (!_cmThread->in_progress()) {
3580     _cmThread->set_started();
3581     CGC_lock->notify();
3582   }
3583 }
3584 
3585 size_t G1CollectedHeap::pending_card_num() {
3586   size_t extra_cards = 0;
3587   JavaThread *curr = Threads::first();
3588   while (curr != NULL) {
3589     DirtyCardQueue& dcq = curr->dirty_card_queue();
3590     extra_cards += dcq.size();
3591     curr = curr->next();
3592   }
3593   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3594   size_t buffer_size = dcqs.buffer_size();
3595   size_t buffer_num = dcqs.completed_buffers_num();
3596 
3597   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3598   // in bytes - not the number of 'entries'. We need to convert
3599   // into a number of cards.
3600   return (buffer_size * buffer_num + extra_cards) / oopSize;
3601 }
3602 
3603 size_t G1CollectedHeap::cards_scanned() {
3604   return g1_rem_set()->cardsScanned();
3605 }
3606 
3607 void
3608 G1CollectedHeap::setup_surviving_young_words() {
3609   assert(_surviving_young_words == NULL, "pre-condition");
3610   uint array_length = g1_policy()->young_cset_region_length();
3611   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3612   if (_surviving_young_words == NULL) {
3613     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3614                           "Not enough space for young surv words summary.");
3615   }
3616   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3617 #ifdef ASSERT
3618   for (uint i = 0;  i < array_length; ++i) {
3619     assert( _surviving_young_words[i] == 0, "memset above" );
3620   }
3621 #endif // !ASSERT
3622 }
3623 
3624 void
3625 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3626   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3627   uint array_length = g1_policy()->young_cset_region_length();
3628   for (uint i = 0; i < array_length; ++i) {
3629     _surviving_young_words[i] += surv_young_words[i];
3630   }
3631 }
3632 
3633 void
3634 G1CollectedHeap::cleanup_surviving_young_words() {
3635   guarantee( _surviving_young_words != NULL, "pre-condition" );
3636   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3637   _surviving_young_words = NULL;
3638 }
3639 
3640 #ifdef ASSERT
3641 class VerifyCSetClosure: public HeapRegionClosure {
3642 public:
3643   bool doHeapRegion(HeapRegion* hr) {
3644     // Here we check that the CSet region's RSet is ready for parallel
3645     // iteration. The fields that we'll verify are only manipulated
3646     // when the region is part of a CSet and is collected. Afterwards,
3647     // we reset these fields when we clear the region's RSet (when the
3648     // region is freed) so they are ready when the region is
3649     // re-allocated. The only exception to this is if there's an
3650     // evacuation failure and instead of freeing the region we leave
3651     // it in the heap. In that case, we reset these fields during
3652     // evacuation failure handling.
3653     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3654 
3655     // Here's a good place to add any other checks we'd like to
3656     // perform on CSet regions.
3657     return false;
3658   }
3659 };
3660 #endif // ASSERT
3661 
3662 #if TASKQUEUE_STATS
3663 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3664   st->print_raw_cr("GC Task Stats");
3665   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3666   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3667 }
3668 
3669 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3670   print_taskqueue_stats_hdr(st);
3671 
3672   TaskQueueStats totals;
3673   const int n = workers() != NULL ? workers()->total_workers() : 1;
3674   for (int i = 0; i < n; ++i) {
3675     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3676     totals += task_queue(i)->stats;
3677   }
3678   st->print_raw("tot "); totals.print(st); st->cr();
3679 
3680   DEBUG_ONLY(totals.verify());
3681 }
3682 
3683 void G1CollectedHeap::reset_taskqueue_stats() {
3684   const int n = workers() != NULL ? workers()->total_workers() : 1;
3685   for (int i = 0; i < n; ++i) {
3686     task_queue(i)->stats.reset();
3687   }
3688 }
3689 #endif // TASKQUEUE_STATS
3690 
3691 void G1CollectedHeap::log_gc_header() {
3692   if (!G1Log::fine()) {
3693     return;
3694   }
3695 
3696   gclog_or_tty->date_stamp(PrintGCDateStamps);
3697   gclog_or_tty->stamp(PrintGCTimeStamps);
3698 
3699   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3700     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3701     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3702 
3703   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3704 }
3705 
3706 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3707   if (!G1Log::fine()) {
3708     return;
3709   }
3710 
3711   if (G1Log::finer()) {
3712     if (evacuation_failed()) {
3713       gclog_or_tty->print(" (to-space exhausted)");
3714     }
3715     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3716     g1_policy()->phase_times()->note_gc_end();
3717     g1_policy()->phase_times()->print(pause_time_sec);
3718     g1_policy()->print_detailed_heap_transition();
3719   } else {
3720     if (evacuation_failed()) {
3721       gclog_or_tty->print("--");
3722     }
3723     g1_policy()->print_heap_transition();
3724     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3725   }
3726   gclog_or_tty->flush();
3727 }
3728 
3729 bool
3730 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3731   assert_at_safepoint(true /* should_be_vm_thread */);
3732   guarantee(!is_gc_active(), "collection is not reentrant");
3733 
3734   if (GC_locker::check_active_before_gc()) {
3735     return false;
3736   }
3737 
3738   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3739   ResourceMark rm;
3740 
3741   print_heap_before_gc();
3742 
3743   HRSPhaseSetter x(HRSPhaseEvacuation);
3744   verify_region_sets_optional();
3745   verify_dirty_young_regions();
3746 
3747   // This call will decide whether this pause is an initial-mark
3748   // pause. If it is, during_initial_mark_pause() will return true
3749   // for the duration of this pause.
3750   g1_policy()->decide_on_conc_mark_initiation();
3751 
3752   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3753   assert(!g1_policy()->during_initial_mark_pause() ||
3754           g1_policy()->gcs_are_young(), "sanity");
3755 
3756   // We also do not allow mixed GCs during marking.
3757   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3758 
3759   // Record whether this pause is an initial mark. When the current
3760   // thread has completed its logging output and it's safe to signal
3761   // the CM thread, the flag's value in the policy has been reset.
3762   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3763 
3764   // Inner scope for scope based logging, timers, and stats collection
3765   {
3766     if (g1_policy()->during_initial_mark_pause()) {
3767       // We are about to start a marking cycle, so we increment the
3768       // full collection counter.
3769       increment_old_marking_cycles_started();
3770     }
3771     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3772 
3773     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3774                                 workers()->active_workers() : 1);
3775     double pause_start_sec = os::elapsedTime();
3776     g1_policy()->phase_times()->note_gc_start(active_workers);
3777     log_gc_header();
3778 
3779     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3780     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3781 
3782     // If the secondary_free_list is not empty, append it to the
3783     // free_list. No need to wait for the cleanup operation to finish;
3784     // the region allocation code will check the secondary_free_list
3785     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3786     // set, skip this step so that the region allocation code has to
3787     // get entries from the secondary_free_list.
3788     if (!G1StressConcRegionFreeing) {
3789       append_secondary_free_list_if_not_empty_with_lock();
3790     }
3791 
3792     assert(check_young_list_well_formed(),
3793       "young list should be well formed");
3794 
3795     // Don't dynamically change the number of GC threads this early.  A value of
3796     // 0 is used to indicate serial work.  When parallel work is done,
3797     // it will be set.
3798 
3799     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3800       IsGCActiveMark x;
3801 
3802       gc_prologue(false);
3803       increment_total_collections(false /* full gc */);
3804       increment_gc_time_stamp();
3805 
3806       verify_before_gc();
3807 
3808       COMPILER2_PRESENT(DerivedPointerTable::clear());
3809 
3810       // Please see comment in g1CollectedHeap.hpp and
3811       // G1CollectedHeap::ref_processing_init() to see how
3812       // reference processing currently works in G1.
3813 
3814       // Enable discovery in the STW reference processor
3815       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3816                                             true /*verify_no_refs*/);
3817 
3818       {
3819         // We want to temporarily turn off discovery by the
3820         // CM ref processor, if necessary, and turn it back on
3821         // on again later if we do. Using a scoped
3822         // NoRefDiscovery object will do this.
3823         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3824 
3825         // Forget the current alloc region (we might even choose it to be part
3826         // of the collection set!).
3827         release_mutator_alloc_region();
3828 
3829         // We should call this after we retire the mutator alloc
3830         // region(s) so that all the ALLOC / RETIRE events are generated
3831         // before the start GC event.
3832         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3833 
3834         // This timing is only used by the ergonomics to handle our pause target.
3835         // It is unclear why this should not include the full pause. We will
3836         // investigate this in CR 7178365.
3837         //
3838         // Preserving the old comment here if that helps the investigation:
3839         //
3840         // The elapsed time induced by the start time below deliberately elides
3841         // the possible verification above.
3842         double sample_start_time_sec = os::elapsedTime();
3843 
3844 #if YOUNG_LIST_VERBOSE
3845         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3846         _young_list->print();
3847         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3848 #endif // YOUNG_LIST_VERBOSE
3849 
3850         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3851 
3852         double scan_wait_start = os::elapsedTime();
3853         // We have to wait until the CM threads finish scanning the
3854         // root regions as it's the only way to ensure that all the
3855         // objects on them have been correctly scanned before we start
3856         // moving them during the GC.
3857         bool waited = _cm->root_regions()->wait_until_scan_finished();
3858         double wait_time_ms = 0.0;
3859         if (waited) {
3860           double scan_wait_end = os::elapsedTime();
3861           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3862         }
3863         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3864 
3865 #if YOUNG_LIST_VERBOSE
3866         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3867         _young_list->print();
3868 #endif // YOUNG_LIST_VERBOSE
3869 
3870         if (g1_policy()->during_initial_mark_pause()) {
3871           concurrent_mark()->checkpointRootsInitialPre();
3872         }
3873 
3874 #if YOUNG_LIST_VERBOSE
3875         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3876         _young_list->print();
3877         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3878 #endif // YOUNG_LIST_VERBOSE
3879 
3880         g1_policy()->finalize_cset(target_pause_time_ms);
3881 
3882         _cm->note_start_of_gc();
3883         // We should not verify the per-thread SATB buffers given that
3884         // we have not filtered them yet (we'll do so during the
3885         // GC). We also call this after finalize_cset() to
3886         // ensure that the CSet has been finalized.
3887         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3888                                  true  /* verify_enqueued_buffers */,
3889                                  false /* verify_thread_buffers */,
3890                                  true  /* verify_fingers */);
3891 
3892         if (_hr_printer.is_active()) {
3893           HeapRegion* hr = g1_policy()->collection_set();
3894           while (hr != NULL) {
3895             G1HRPrinter::RegionType type;
3896             if (!hr->is_young()) {
3897               type = G1HRPrinter::Old;
3898             } else if (hr->is_survivor()) {
3899               type = G1HRPrinter::Survivor;
3900             } else {
3901               type = G1HRPrinter::Eden;
3902             }
3903             _hr_printer.cset(hr);
3904             hr = hr->next_in_collection_set();
3905           }
3906         }
3907 
3908 #ifdef ASSERT
3909         VerifyCSetClosure cl;
3910         collection_set_iterate(&cl);
3911 #endif // ASSERT
3912 
3913         setup_surviving_young_words();
3914 
3915         // Initialize the GC alloc regions.
3916         init_gc_alloc_regions();
3917 
3918         // Actually do the work...
3919         evacuate_collection_set();
3920 
3921         // We do this to mainly verify the per-thread SATB buffers
3922         // (which have been filtered by now) since we didn't verify
3923         // them earlier. No point in re-checking the stacks / enqueued
3924         // buffers given that the CSet has not changed since last time
3925         // we checked.
3926         _cm->verify_no_cset_oops(false /* verify_stacks */,
3927                                  false /* verify_enqueued_buffers */,
3928                                  true  /* verify_thread_buffers */,
3929                                  true  /* verify_fingers */);
3930 
3931         free_collection_set(g1_policy()->collection_set());
3932         g1_policy()->clear_collection_set();
3933 
3934         cleanup_surviving_young_words();
3935 
3936         // Start a new incremental collection set for the next pause.
3937         g1_policy()->start_incremental_cset_building();
3938 
3939         // Clear the _cset_fast_test bitmap in anticipation of adding
3940         // regions to the incremental collection set for the next
3941         // evacuation pause.
3942         clear_cset_fast_test();
3943 
3944         _young_list->reset_sampled_info();
3945 
3946         // Don't check the whole heap at this point as the
3947         // GC alloc regions from this pause have been tagged
3948         // as survivors and moved on to the survivor list.
3949         // Survivor regions will fail the !is_young() check.
3950         assert(check_young_list_empty(false /* check_heap */),
3951           "young list should be empty");
3952 
3953 #if YOUNG_LIST_VERBOSE
3954         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3955         _young_list->print();
3956 #endif // YOUNG_LIST_VERBOSE
3957 
3958         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3959                                             _young_list->first_survivor_region(),
3960                                             _young_list->last_survivor_region());
3961 
3962         _young_list->reset_auxilary_lists();
3963 
3964         if (evacuation_failed()) {
3965           _summary_bytes_used = recalculate_used();
3966         } else {
3967           // The "used" of the the collection set have already been subtracted
3968           // when they were freed.  Add in the bytes evacuated.
3969           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3970         }
3971 
3972         if (g1_policy()->during_initial_mark_pause()) {
3973           // We have to do this before we notify the CM threads that
3974           // they can start working to make sure that all the
3975           // appropriate initialization is done on the CM object.
3976           concurrent_mark()->checkpointRootsInitialPost();
3977           set_marking_started();
3978           // Note that we don't actually trigger the CM thread at
3979           // this point. We do that later when we're sure that
3980           // the current thread has completed its logging output.
3981         }
3982 
3983         allocate_dummy_regions();
3984 
3985 #if YOUNG_LIST_VERBOSE
3986         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3987         _young_list->print();
3988         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3989 #endif // YOUNG_LIST_VERBOSE
3990 
3991         init_mutator_alloc_region();
3992 
3993         {
3994           size_t expand_bytes = g1_policy()->expansion_amount();
3995           if (expand_bytes > 0) {
3996             size_t bytes_before = capacity();
3997             // No need for an ergo verbose message here,
3998             // expansion_amount() does this when it returns a value > 0.
3999             if (!expand(expand_bytes)) {
4000               // We failed to expand the heap so let's verify that
4001               // committed/uncommitted amount match the backing store
4002               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4003               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4004             }
4005           }
4006         }
4007 
4008         // We redo the verificaiton but now wrt to the new CSet which
4009         // has just got initialized after the previous CSet was freed.
4010         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4011                                  true  /* verify_enqueued_buffers */,
4012                                  true  /* verify_thread_buffers */,
4013                                  true  /* verify_fingers */);
4014         _cm->note_end_of_gc();
4015 
4016         // This timing is only used by the ergonomics to handle our pause target.
4017         // It is unclear why this should not include the full pause. We will
4018         // investigate this in CR 7178365.
4019         double sample_end_time_sec = os::elapsedTime();
4020         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4021         g1_policy()->record_collection_pause_end(pause_time_ms);
4022 
4023         MemoryService::track_memory_usage();
4024 
4025         // In prepare_for_verify() below we'll need to scan the deferred
4026         // update buffers to bring the RSets up-to-date if
4027         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4028         // the update buffers we'll probably need to scan cards on the
4029         // regions we just allocated to (i.e., the GC alloc
4030         // regions). However, during the last GC we called
4031         // set_saved_mark() on all the GC alloc regions, so card
4032         // scanning might skip the [saved_mark_word()...top()] area of
4033         // those regions (i.e., the area we allocated objects into
4034         // during the last GC). But it shouldn't. Given that
4035         // saved_mark_word() is conditional on whether the GC time stamp
4036         // on the region is current or not, by incrementing the GC time
4037         // stamp here we invalidate all the GC time stamps on all the
4038         // regions and saved_mark_word() will simply return top() for
4039         // all the regions. This is a nicer way of ensuring this rather
4040         // than iterating over the regions and fixing them. In fact, the
4041         // GC time stamp increment here also ensures that
4042         // saved_mark_word() will return top() between pauses, i.e.,
4043         // during concurrent refinement. So we don't need the
4044         // is_gc_active() check to decided which top to use when
4045         // scanning cards (see CR 7039627).
4046         increment_gc_time_stamp();
4047 
4048         verify_after_gc();
4049 
4050         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4051         ref_processor_stw()->verify_no_references_recorded();
4052 
4053         // CM reference discovery will be re-enabled if necessary.
4054       }
4055 
4056       // We should do this after we potentially expand the heap so
4057       // that all the COMMIT events are generated before the end GC
4058       // event, and after we retire the GC alloc regions so that all
4059       // RETIRE events are generated before the end GC event.
4060       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4061 
4062       if (mark_in_progress()) {
4063         concurrent_mark()->update_g1_committed();
4064       }
4065 
4066 #ifdef TRACESPINNING
4067       ParallelTaskTerminator::print_termination_counts();
4068 #endif
4069 
4070       gc_epilogue(false);
4071     }
4072 
4073     // Print the remainder of the GC log output.
4074     log_gc_footer(os::elapsedTime() - pause_start_sec);
4075 
4076     // It is not yet to safe to tell the concurrent mark to
4077     // start as we have some optional output below. We don't want the
4078     // output from the concurrent mark thread interfering with this
4079     // logging output either.
4080 
4081     _hrs.verify_optional();
4082     verify_region_sets_optional();
4083 
4084     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4085     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4086 
4087     print_heap_after_gc();
4088 
4089     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4090     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4091     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4092     // before any GC notifications are raised.
4093     g1mm()->update_sizes();
4094   }
4095 
4096   if (G1SummarizeRSetStats &&
4097       (G1SummarizeRSetStatsPeriod > 0) &&
4098       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
4099     g1_rem_set()->print_summary_info();
4100   }
4101 
4102   // It should now be safe to tell the concurrent mark thread to start
4103   // without its logging output interfering with the logging output
4104   // that came from the pause.
4105 
4106   if (should_start_conc_mark) {
4107     // CAUTION: after the doConcurrentMark() call below,
4108     // the concurrent marking thread(s) could be running
4109     // concurrently with us. Make sure that anything after
4110     // this point does not assume that we are the only GC thread
4111     // running. Note: of course, the actual marking work will
4112     // not start until the safepoint itself is released in
4113     // ConcurrentGCThread::safepoint_desynchronize().
4114     doConcurrentMark();
4115   }
4116 
4117   return true;
4118 }
4119 
4120 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4121 {
4122   size_t gclab_word_size;
4123   switch (purpose) {
4124     case GCAllocForSurvived:
4125       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4126       break;
4127     case GCAllocForTenured:
4128       gclab_word_size = _old_plab_stats.desired_plab_sz();
4129       break;
4130     default:
4131       assert(false, "unknown GCAllocPurpose");
4132       gclab_word_size = _old_plab_stats.desired_plab_sz();
4133       break;
4134   }
4135 
4136   // Prevent humongous PLAB sizes for two reasons:
4137   // * PLABs are allocated using a similar paths as oops, but should
4138   //   never be in a humongous region
4139   // * Allowing humongous PLABs needlessly churns the region free lists
4140   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4141 }
4142 
4143 void G1CollectedHeap::init_mutator_alloc_region() {
4144   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4145   _mutator_alloc_region.init();
4146 }
4147 
4148 void G1CollectedHeap::release_mutator_alloc_region() {
4149   _mutator_alloc_region.release();
4150   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4151 }
4152 
4153 void G1CollectedHeap::init_gc_alloc_regions() {
4154   assert_at_safepoint(true /* should_be_vm_thread */);
4155 
4156   _survivor_gc_alloc_region.init();
4157   _old_gc_alloc_region.init();
4158   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4159   _retained_old_gc_alloc_region = NULL;
4160 
4161   // We will discard the current GC alloc region if:
4162   // a) it's in the collection set (it can happen!),
4163   // b) it's already full (no point in using it),
4164   // c) it's empty (this means that it was emptied during
4165   // a cleanup and it should be on the free list now), or
4166   // d) it's humongous (this means that it was emptied
4167   // during a cleanup and was added to the free list, but
4168   // has been subseqently used to allocate a humongous
4169   // object that may be less than the region size).
4170   if (retained_region != NULL &&
4171       !retained_region->in_collection_set() &&
4172       !(retained_region->top() == retained_region->end()) &&
4173       !retained_region->is_empty() &&
4174       !retained_region->isHumongous()) {
4175     retained_region->set_saved_mark();
4176     // The retained region was added to the old region set when it was
4177     // retired. We have to remove it now, since we don't allow regions
4178     // we allocate to in the region sets. We'll re-add it later, when
4179     // it's retired again.
4180     _old_set.remove(retained_region);
4181     bool during_im = g1_policy()->during_initial_mark_pause();
4182     retained_region->note_start_of_copying(during_im);
4183     _old_gc_alloc_region.set(retained_region);
4184     _hr_printer.reuse(retained_region);
4185   }
4186 }
4187 
4188 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers) {
4189   _survivor_gc_alloc_region.release();
4190   // If we have an old GC alloc region to release, we'll save it in
4191   // _retained_old_gc_alloc_region. If we don't
4192   // _retained_old_gc_alloc_region will become NULL. This is what we
4193   // want either way so no reason to check explicitly for either
4194   // condition.
4195   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4196 
4197   if (ResizePLAB) {
4198     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4199     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4200   }
4201 }
4202 
4203 void G1CollectedHeap::abandon_gc_alloc_regions() {
4204   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4205   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4206   _retained_old_gc_alloc_region = NULL;
4207 }
4208 
4209 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4210   _drain_in_progress = false;
4211   set_evac_failure_closure(cl);
4212   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4213 }
4214 
4215 void G1CollectedHeap::finalize_for_evac_failure() {
4216   assert(_evac_failure_scan_stack != NULL &&
4217          _evac_failure_scan_stack->length() == 0,
4218          "Postcondition");
4219   assert(!_drain_in_progress, "Postcondition");
4220   delete _evac_failure_scan_stack;
4221   _evac_failure_scan_stack = NULL;
4222 }
4223 
4224 void G1CollectedHeap::remove_self_forwarding_pointers() {
4225   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4226 
4227   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4228 
4229   if (G1CollectedHeap::use_parallel_gc_threads()) {
4230     set_par_threads();
4231     workers()->run_task(&rsfp_task);
4232     set_par_threads(0);
4233   } else {
4234     rsfp_task.work(0);
4235   }
4236 
4237   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4238 
4239   // Reset the claim values in the regions in the collection set.
4240   reset_cset_heap_region_claim_values();
4241 
4242   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4243 
4244   // Now restore saved marks, if any.
4245   assert(_objs_with_preserved_marks.size() ==
4246             _preserved_marks_of_objs.size(), "Both or none.");
4247   while (!_objs_with_preserved_marks.is_empty()) {
4248     oop obj = _objs_with_preserved_marks.pop();
4249     markOop m = _preserved_marks_of_objs.pop();
4250     obj->set_mark(m);
4251   }
4252   _objs_with_preserved_marks.clear(true);
4253   _preserved_marks_of_objs.clear(true);
4254 }
4255 
4256 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4257   _evac_failure_scan_stack->push(obj);
4258 }
4259 
4260 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4261   assert(_evac_failure_scan_stack != NULL, "precondition");
4262 
4263   while (_evac_failure_scan_stack->length() > 0) {
4264      oop obj = _evac_failure_scan_stack->pop();
4265      _evac_failure_closure->set_region(heap_region_containing(obj));
4266      obj->oop_iterate_backwards(_evac_failure_closure);
4267   }
4268 }
4269 
4270 oop
4271 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4272                                                oop old) {
4273   assert(obj_in_cs(old),
4274          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4275                  (HeapWord*) old));
4276   markOop m = old->mark();
4277   oop forward_ptr = old->forward_to_atomic(old);
4278   if (forward_ptr == NULL) {
4279     // Forward-to-self succeeded.
4280 
4281     if (_evac_failure_closure != cl) {
4282       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4283       assert(!_drain_in_progress,
4284              "Should only be true while someone holds the lock.");
4285       // Set the global evac-failure closure to the current thread's.
4286       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4287       set_evac_failure_closure(cl);
4288       // Now do the common part.
4289       handle_evacuation_failure_common(old, m);
4290       // Reset to NULL.
4291       set_evac_failure_closure(NULL);
4292     } else {
4293       // The lock is already held, and this is recursive.
4294       assert(_drain_in_progress, "This should only be the recursive case.");
4295       handle_evacuation_failure_common(old, m);
4296     }
4297     return old;
4298   } else {
4299     // Forward-to-self failed. Either someone else managed to allocate
4300     // space for this object (old != forward_ptr) or they beat us in
4301     // self-forwarding it (old == forward_ptr).
4302     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4303            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4304                    "should not be in the CSet",
4305                    (HeapWord*) old, (HeapWord*) forward_ptr));
4306     return forward_ptr;
4307   }
4308 }
4309 
4310 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4311   set_evacuation_failed(true);
4312 
4313   preserve_mark_if_necessary(old, m);
4314 
4315   HeapRegion* r = heap_region_containing(old);
4316   if (!r->evacuation_failed()) {
4317     r->set_evacuation_failed(true);
4318     _hr_printer.evac_failure(r);
4319   }
4320 
4321   push_on_evac_failure_scan_stack(old);
4322 
4323   if (!_drain_in_progress) {
4324     // prevent recursion in copy_to_survivor_space()
4325     _drain_in_progress = true;
4326     drain_evac_failure_scan_stack();
4327     _drain_in_progress = false;
4328   }
4329 }
4330 
4331 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4332   assert(evacuation_failed(), "Oversaving!");
4333   // We want to call the "for_promotion_failure" version only in the
4334   // case of a promotion failure.
4335   if (m->must_be_preserved_for_promotion_failure(obj)) {
4336     _objs_with_preserved_marks.push(obj);
4337     _preserved_marks_of_objs.push(m);
4338   }
4339 }
4340 
4341 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4342                                                   size_t word_size) {
4343   if (purpose == GCAllocForSurvived) {
4344     HeapWord* result = survivor_attempt_allocation(word_size);
4345     if (result != NULL) {
4346       return result;
4347     } else {
4348       // Let's try to allocate in the old gen in case we can fit the
4349       // object there.
4350       return old_attempt_allocation(word_size);
4351     }
4352   } else {
4353     assert(purpose ==  GCAllocForTenured, "sanity");
4354     HeapWord* result = old_attempt_allocation(word_size);
4355     if (result != NULL) {
4356       return result;
4357     } else {
4358       // Let's try to allocate in the survivors in case we can fit the
4359       // object there.
4360       return survivor_attempt_allocation(word_size);
4361     }
4362   }
4363 
4364   ShouldNotReachHere();
4365   // Trying to keep some compilers happy.
4366   return NULL;
4367 }
4368 
4369 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4370   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4371 
4372 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4373   : _g1h(g1h),
4374     _refs(g1h->task_queue(queue_num)),
4375     _dcq(&g1h->dirty_card_queue_set()),
4376     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4377     _g1_rem(g1h->g1_rem_set()),
4378     _hash_seed(17), _queue_num(queue_num),
4379     _term_attempts(0),
4380     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4381     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4382     _age_table(false),
4383     _strong_roots_time(0), _term_time(0),
4384     _alloc_buffer_waste(0), _undo_waste(0) {
4385   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4386   // we "sacrifice" entry 0 to keep track of surviving bytes for
4387   // non-young regions (where the age is -1)
4388   // We also add a few elements at the beginning and at the end in
4389   // an attempt to eliminate cache contention
4390   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4391   uint array_length = PADDING_ELEM_NUM +
4392                       real_length +
4393                       PADDING_ELEM_NUM;
4394   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4395   if (_surviving_young_words_base == NULL)
4396     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4397                           "Not enough space for young surv histo.");
4398   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4399   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4400 
4401   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4402   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4403 
4404   _start = os::elapsedTime();
4405 }
4406 
4407 void
4408 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4409 {
4410   st->print_raw_cr("GC Termination Stats");
4411   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4412                    " ------waste (KiB)------");
4413   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4414                    "  total   alloc    undo");
4415   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4416                    " ------- ------- -------");
4417 }
4418 
4419 void
4420 G1ParScanThreadState::print_termination_stats(int i,
4421                                               outputStream* const st) const
4422 {
4423   const double elapsed_ms = elapsed_time() * 1000.0;
4424   const double s_roots_ms = strong_roots_time() * 1000.0;
4425   const double term_ms    = term_time() * 1000.0;
4426   st->print_cr("%3d %9.2f %9.2f %6.2f "
4427                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4428                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4429                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4430                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4431                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4432                alloc_buffer_waste() * HeapWordSize / K,
4433                undo_waste() * HeapWordSize / K);
4434 }
4435 
4436 #ifdef ASSERT
4437 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4438   assert(ref != NULL, "invariant");
4439   assert(UseCompressedOops, "sanity");
4440   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4441   oop p = oopDesc::load_decode_heap_oop(ref);
4442   assert(_g1h->is_in_g1_reserved(p),
4443          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4444   return true;
4445 }
4446 
4447 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4448   assert(ref != NULL, "invariant");
4449   if (has_partial_array_mask(ref)) {
4450     // Must be in the collection set--it's already been copied.
4451     oop p = clear_partial_array_mask(ref);
4452     assert(_g1h->obj_in_cs(p),
4453            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4454   } else {
4455     oop p = oopDesc::load_decode_heap_oop(ref);
4456     assert(_g1h->is_in_g1_reserved(p),
4457            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4458   }
4459   return true;
4460 }
4461 
4462 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4463   if (ref.is_narrow()) {
4464     return verify_ref((narrowOop*) ref);
4465   } else {
4466     return verify_ref((oop*) ref);
4467   }
4468 }
4469 #endif // ASSERT
4470 
4471 void G1ParScanThreadState::trim_queue() {
4472   assert(_evac_cl != NULL, "not set");
4473   assert(_evac_failure_cl != NULL, "not set");
4474   assert(_partial_scan_cl != NULL, "not set");
4475 
4476   StarTask ref;
4477   do {
4478     // Drain the overflow stack first, so other threads can steal.
4479     while (refs()->pop_overflow(ref)) {
4480       deal_with_reference(ref);
4481     }
4482 
4483     while (refs()->pop_local(ref)) {
4484       deal_with_reference(ref);
4485     }
4486   } while (!refs()->is_empty());
4487 }
4488 
4489 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4490                                      G1ParScanThreadState* par_scan_state) :
4491   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4492   _par_scan_state(par_scan_state),
4493   _worker_id(par_scan_state->queue_num()),
4494   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4495   _mark_in_progress(_g1->mark_in_progress()) { }
4496 
4497 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4498 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4499 #ifdef ASSERT
4500   HeapRegion* hr = _g1->heap_region_containing(obj);
4501   assert(hr != NULL, "sanity");
4502   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4503 #endif // ASSERT
4504 
4505   // We know that the object is not moving so it's safe to read its size.
4506   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4507 }
4508 
4509 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4510 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4511   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4512 #ifdef ASSERT
4513   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4514   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4515   assert(from_obj != to_obj, "should not be self-forwarded");
4516 
4517   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4518   assert(from_hr != NULL, "sanity");
4519   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4520 
4521   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4522   assert(to_hr != NULL, "sanity");
4523   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4524 #endif // ASSERT
4525 
4526   // The object might be in the process of being copied by another
4527   // worker so we cannot trust that its to-space image is
4528   // well-formed. So we have to read its size from its from-space
4529   // image which we know should not be changing.
4530   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4531 }
4532 
4533 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4534 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4535   ::copy_to_survivor_space(oop old) {
4536   size_t word_sz = old->size();
4537   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4538   // +1 to make the -1 indexes valid...
4539   int       young_index = from_region->young_index_in_cset()+1;
4540   assert( (from_region->is_young() && young_index >  0) ||
4541          (!from_region->is_young() && young_index == 0), "invariant" );
4542   G1CollectorPolicy* g1p = _g1->g1_policy();
4543   markOop m = old->mark();
4544   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4545                                            : m->age();
4546   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4547                                                              word_sz);
4548   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4549 #ifndef PRODUCT
4550   // Should this evacuation fail?
4551   if (_g1->evacuation_should_fail()) {
4552     if (obj_ptr != NULL) {
4553       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4554       obj_ptr = NULL;
4555     }
4556   }
4557 #endif // !PRODUCT
4558 
4559   if (obj_ptr == NULL) {
4560     // This will either forward-to-self, or detect that someone else has
4561     // installed a forwarding pointer.
4562     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4563     return _g1->handle_evacuation_failure_par(cl, old);
4564   }
4565 
4566   oop obj = oop(obj_ptr);
4567 
4568   // We're going to allocate linearly, so might as well prefetch ahead.
4569   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4570 
4571   oop forward_ptr = old->forward_to_atomic(obj);
4572   if (forward_ptr == NULL) {
4573     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4574     if (g1p->track_object_age(alloc_purpose)) {
4575       // We could simply do obj->incr_age(). However, this causes a
4576       // performance issue. obj->incr_age() will first check whether
4577       // the object has a displaced mark by checking its mark word;
4578       // getting the mark word from the new location of the object
4579       // stalls. So, given that we already have the mark word and we
4580       // are about to install it anyway, it's better to increase the
4581       // age on the mark word, when the object does not have a
4582       // displaced mark word. We're not expecting many objects to have
4583       // a displaced marked word, so that case is not optimized
4584       // further (it could be...) and we simply call obj->incr_age().
4585 
4586       if (m->has_displaced_mark_helper()) {
4587         // in this case, we have to install the mark word first,
4588         // otherwise obj looks to be forwarded (the old mark word,
4589         // which contains the forward pointer, was copied)
4590         obj->set_mark(m);
4591         obj->incr_age();
4592       } else {
4593         m = m->incr_age();
4594         obj->set_mark(m);
4595       }
4596       _par_scan_state->age_table()->add(obj, word_sz);
4597     } else {
4598       obj->set_mark(m);
4599     }
4600 
4601     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4602     surv_young_words[young_index] += word_sz;
4603 
4604     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4605       // We keep track of the next start index in the length field of
4606       // the to-space object. The actual length can be found in the
4607       // length field of the from-space object.
4608       arrayOop(obj)->set_length(0);
4609       oop* old_p = set_partial_array_mask(old);
4610       _par_scan_state->push_on_queue(old_p);
4611     } else {
4612       // No point in using the slower heap_region_containing() method,
4613       // given that we know obj is in the heap.
4614       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4615       obj->oop_iterate_backwards(&_scanner);
4616     }
4617   } else {
4618     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4619     obj = forward_ptr;
4620   }
4621   return obj;
4622 }
4623 
4624 template <class T>
4625 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4626   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4627     _scanned_klass->record_modified_oops();
4628   }
4629 }
4630 
4631 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4632 template <class T>
4633 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4634 ::do_oop_work(T* p) {
4635   oop obj = oopDesc::load_decode_heap_oop(p);
4636   assert(barrier != G1BarrierRS || obj != NULL,
4637          "Precondition: G1BarrierRS implies obj is non-NULL");
4638 
4639   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4640 
4641   // here the null check is implicit in the cset_fast_test() test
4642   if (_g1->in_cset_fast_test(obj)) {
4643     oop forwardee;
4644     if (obj->is_forwarded()) {
4645       forwardee = obj->forwardee();
4646     } else {
4647       forwardee = copy_to_survivor_space(obj);
4648     }
4649     assert(forwardee != NULL, "forwardee should not be NULL");
4650     oopDesc::encode_store_heap_oop(p, forwardee);
4651     if (do_mark_object && forwardee != obj) {
4652       // If the object is self-forwarded we don't need to explicitly
4653       // mark it, the evacuation failure protocol will do so.
4654       mark_forwarded_object(obj, forwardee);
4655     }
4656 
4657     // When scanning the RS, we only care about objs in CS.
4658     if (barrier == G1BarrierRS) {
4659       _par_scan_state->update_rs(_from, p, _worker_id);
4660     } else if (barrier == G1BarrierKlass) {
4661       do_klass_barrier(p, forwardee);
4662     }
4663   } else {
4664     // The object is not in collection set. If we're a root scanning
4665     // closure during an initial mark pause (i.e. do_mark_object will
4666     // be true) then attempt to mark the object.
4667     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4668       mark_object(obj);
4669     }
4670   }
4671 
4672   if (barrier == G1BarrierEvac && obj != NULL) {
4673     _par_scan_state->update_rs(_from, p, _worker_id);
4674   }
4675 
4676   if (do_gen_barrier && obj != NULL) {
4677     par_do_barrier(p);
4678   }
4679 }
4680 
4681 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4682 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4683 
4684 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4685   assert(has_partial_array_mask(p), "invariant");
4686   oop from_obj = clear_partial_array_mask(p);
4687 
4688   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4689   assert(from_obj->is_objArray(), "must be obj array");
4690   objArrayOop from_obj_array = objArrayOop(from_obj);
4691   // The from-space object contains the real length.
4692   int length                 = from_obj_array->length();
4693 
4694   assert(from_obj->is_forwarded(), "must be forwarded");
4695   oop to_obj                 = from_obj->forwardee();
4696   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4697   objArrayOop to_obj_array   = objArrayOop(to_obj);
4698   // We keep track of the next start index in the length field of the
4699   // to-space object.
4700   int next_index             = to_obj_array->length();
4701   assert(0 <= next_index && next_index < length,
4702          err_msg("invariant, next index: %d, length: %d", next_index, length));
4703 
4704   int start                  = next_index;
4705   int end                    = length;
4706   int remainder              = end - start;
4707   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4708   if (remainder > 2 * ParGCArrayScanChunk) {
4709     end = start + ParGCArrayScanChunk;
4710     to_obj_array->set_length(end);
4711     // Push the remainder before we process the range in case another
4712     // worker has run out of things to do and can steal it.
4713     oop* from_obj_p = set_partial_array_mask(from_obj);
4714     _par_scan_state->push_on_queue(from_obj_p);
4715   } else {
4716     assert(length == end, "sanity");
4717     // We'll process the final range for this object. Restore the length
4718     // so that the heap remains parsable in case of evacuation failure.
4719     to_obj_array->set_length(end);
4720   }
4721   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4722   // Process indexes [start,end). It will also process the header
4723   // along with the first chunk (i.e., the chunk with start == 0).
4724   // Note that at this point the length field of to_obj_array is not
4725   // correct given that we are using it to keep track of the next
4726   // start index. oop_iterate_range() (thankfully!) ignores the length
4727   // field and only relies on the start / end parameters.  It does
4728   // however return the size of the object which will be incorrect. So
4729   // we have to ignore it even if we wanted to use it.
4730   to_obj_array->oop_iterate_range(&_scanner, start, end);
4731 }
4732 
4733 class G1ParEvacuateFollowersClosure : public VoidClosure {
4734 protected:
4735   G1CollectedHeap*              _g1h;
4736   G1ParScanThreadState*         _par_scan_state;
4737   RefToScanQueueSet*            _queues;
4738   ParallelTaskTerminator*       _terminator;
4739 
4740   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4741   RefToScanQueueSet*      queues()         { return _queues; }
4742   ParallelTaskTerminator* terminator()     { return _terminator; }
4743 
4744 public:
4745   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4746                                 G1ParScanThreadState* par_scan_state,
4747                                 RefToScanQueueSet* queues,
4748                                 ParallelTaskTerminator* terminator)
4749     : _g1h(g1h), _par_scan_state(par_scan_state),
4750       _queues(queues), _terminator(terminator) {}
4751 
4752   void do_void();
4753 
4754 private:
4755   inline bool offer_termination();
4756 };
4757 
4758 bool G1ParEvacuateFollowersClosure::offer_termination() {
4759   G1ParScanThreadState* const pss = par_scan_state();
4760   pss->start_term_time();
4761   const bool res = terminator()->offer_termination();
4762   pss->end_term_time();
4763   return res;
4764 }
4765 
4766 void G1ParEvacuateFollowersClosure::do_void() {
4767   StarTask stolen_task;
4768   G1ParScanThreadState* const pss = par_scan_state();
4769   pss->trim_queue();
4770 
4771   do {
4772     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4773       assert(pss->verify_task(stolen_task), "sanity");
4774       if (stolen_task.is_narrow()) {
4775         pss->deal_with_reference((narrowOop*) stolen_task);
4776       } else {
4777         pss->deal_with_reference((oop*) stolen_task);
4778       }
4779 
4780       // We've just processed a reference and we might have made
4781       // available new entries on the queues. So we have to make sure
4782       // we drain the queues as necessary.
4783       pss->trim_queue();
4784     }
4785   } while (!offer_termination());
4786 
4787   pss->retire_alloc_buffers();
4788 }
4789 
4790 class G1KlassScanClosure : public KlassClosure {
4791  G1ParCopyHelper* _closure;
4792  bool             _process_only_dirty;
4793  int              _count;
4794  public:
4795   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4796       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4797   void do_klass(Klass* klass) {
4798     // If the klass has not been dirtied we know that there's
4799     // no references into  the young gen and we can skip it.
4800    if (!_process_only_dirty || klass->has_modified_oops()) {
4801       // Clean the klass since we're going to scavenge all the metadata.
4802       klass->clear_modified_oops();
4803 
4804       // Tell the closure that this klass is the Klass to scavenge
4805       // and is the one to dirty if oops are left pointing into the young gen.
4806       _closure->set_scanned_klass(klass);
4807 
4808       klass->oops_do(_closure);
4809 
4810       _closure->set_scanned_klass(NULL);
4811     }
4812     _count++;
4813   }
4814 };
4815 
4816 class G1ParTask : public AbstractGangTask {
4817 protected:
4818   G1CollectedHeap*       _g1h;
4819   RefToScanQueueSet      *_queues;
4820   ParallelTaskTerminator _terminator;
4821   uint _n_workers;
4822 
4823   Mutex _stats_lock;
4824   Mutex* stats_lock() { return &_stats_lock; }
4825 
4826   size_t getNCards() {
4827     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4828       / G1BlockOffsetSharedArray::N_bytes;
4829   }
4830 
4831 public:
4832   G1ParTask(G1CollectedHeap* g1h,
4833             RefToScanQueueSet *task_queues)
4834     : AbstractGangTask("G1 collection"),
4835       _g1h(g1h),
4836       _queues(task_queues),
4837       _terminator(0, _queues),
4838       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4839   {}
4840 
4841   RefToScanQueueSet* queues() { return _queues; }
4842 
4843   RefToScanQueue *work_queue(int i) {
4844     return queues()->queue(i);
4845   }
4846 
4847   ParallelTaskTerminator* terminator() { return &_terminator; }
4848 
4849   virtual void set_for_termination(int active_workers) {
4850     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4851     // in the young space (_par_seq_tasks) in the G1 heap
4852     // for SequentialSubTasksDone.
4853     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4854     // both of which need setting by set_n_termination().
4855     _g1h->SharedHeap::set_n_termination(active_workers);
4856     _g1h->set_n_termination(active_workers);
4857     terminator()->reset_for_reuse(active_workers);
4858     _n_workers = active_workers;
4859   }
4860 
4861   void work(uint worker_id) {
4862     if (worker_id >= _n_workers) return;  // no work needed this round
4863 
4864     double start_time_ms = os::elapsedTime() * 1000.0;
4865     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4866 
4867     {
4868       ResourceMark rm;
4869       HandleMark   hm;
4870 
4871       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4872 
4873       G1ParScanThreadState            pss(_g1h, worker_id);
4874       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
4875       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4876       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
4877 
4878       pss.set_evac_closure(&scan_evac_cl);
4879       pss.set_evac_failure_closure(&evac_failure_cl);
4880       pss.set_partial_scan_closure(&partial_scan_cl);
4881 
4882       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4883       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
4884 
4885       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4886       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4887 
4888       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
4889       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4890       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4891 
4892       OopClosure*                    scan_root_cl = &only_scan_root_cl;
4893       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
4894 
4895       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4896         // We also need to mark copied objects.
4897         scan_root_cl = &scan_mark_root_cl;
4898         scan_klasses_cl = &scan_mark_klasses_cl_s;
4899       }
4900 
4901       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
4902 
4903       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
4904 
4905       pss.start_strong_roots();
4906       _g1h->g1_process_strong_roots(/* is scavenging */ true,
4907                                     SharedHeap::ScanningOption(so),
4908                                     scan_root_cl,
4909                                     &push_heap_rs_cl,
4910                                     scan_klasses_cl,
4911                                     worker_id);
4912       pss.end_strong_roots();
4913 
4914       {
4915         double start = os::elapsedTime();
4916         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4917         evac.do_void();
4918         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4919         double term_ms = pss.term_time()*1000.0;
4920         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4921         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4922       }
4923       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4924       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4925 
4926       if (ParallelGCVerbose) {
4927         MutexLocker x(stats_lock());
4928         pss.print_termination_stats(worker_id);
4929       }
4930 
4931       assert(pss.refs()->is_empty(), "should be empty");
4932 
4933       // Close the inner scope so that the ResourceMark and HandleMark
4934       // destructors are executed here and are included as part of the
4935       // "GC Worker Time".
4936     }
4937 
4938     double end_time_ms = os::elapsedTime() * 1000.0;
4939     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4940   }
4941 };
4942 
4943 // *** Common G1 Evacuation Stuff
4944 
4945 // Closures that support the filtering of CodeBlobs scanned during
4946 // external root scanning.
4947 
4948 // Closure applied to reference fields in code blobs (specifically nmethods)
4949 // to determine whether an nmethod contains references that point into
4950 // the collection set. Used as a predicate when walking code roots so
4951 // that only nmethods that point into the collection set are added to the
4952 // 'marked' list.
4953 
4954 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
4955 
4956   class G1PointsIntoCSOopClosure : public OopClosure {
4957     G1CollectedHeap* _g1;
4958     bool _points_into_cs;
4959   public:
4960     G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
4961       _g1(g1), _points_into_cs(false) { }
4962 
4963     bool points_into_cs() const { return _points_into_cs; }
4964 
4965     template <class T>
4966     void do_oop_nv(T* p) {
4967       if (!_points_into_cs) {
4968         T heap_oop = oopDesc::load_heap_oop(p);
4969         if (!oopDesc::is_null(heap_oop) &&
4970             _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
4971           _points_into_cs = true;
4972         }
4973       }
4974     }
4975 
4976     virtual void do_oop(oop* p)        { do_oop_nv(p); }
4977     virtual void do_oop(narrowOop* p)  { do_oop_nv(p); }
4978   };
4979 
4980   G1CollectedHeap* _g1;
4981 
4982 public:
4983   G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
4984     CodeBlobToOopClosure(cl, true), _g1(g1) { }
4985 
4986   virtual void do_code_blob(CodeBlob* cb) {
4987     nmethod* nm = cb->as_nmethod_or_null();
4988     if (nm != NULL && !(nm->test_oops_do_mark())) {
4989       G1PointsIntoCSOopClosure predicate_cl(_g1);
4990       nm->oops_do(&predicate_cl);
4991 
4992       if (predicate_cl.points_into_cs()) {
4993         // At least one of the reference fields or the oop relocations
4994         // in the nmethod points into the collection set. We have to
4995         // 'mark' this nmethod.
4996         // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
4997         // or MarkingCodeBlobClosure::do_code_blob() change.
4998         if (!nm->test_set_oops_do_mark()) {
4999           do_newly_marked_nmethod(nm);
5000         }
5001       }
5002     }
5003   }
5004 };
5005 
5006 // This method is run in a GC worker.
5007 
5008 void
5009 G1CollectedHeap::
5010 g1_process_strong_roots(bool is_scavenging,
5011                         ScanningOption so,
5012                         OopClosure* scan_non_heap_roots,
5013                         OopsInHeapRegionClosure* scan_rs,
5014                         G1KlassScanClosure* scan_klasses,
5015                         int worker_i) {
5016 
5017   // First scan the strong roots
5018   double ext_roots_start = os::elapsedTime();
5019   double closure_app_time_sec = 0.0;
5020 
5021   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5022 
5023   // Walk the code cache w/o buffering, because StarTask cannot handle
5024   // unaligned oop locations.
5025   G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5026 
5027   process_strong_roots(false, // no scoping; this is parallel code
5028                        is_scavenging, so,
5029                        &buf_scan_non_heap_roots,
5030                        &eager_scan_code_roots,
5031                        scan_klasses
5032                        );
5033 
5034   // Now the CM ref_processor roots.
5035   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5036     // We need to treat the discovered reference lists of the
5037     // concurrent mark ref processor as roots and keep entries
5038     // (which are added by the marking threads) on them live
5039     // until they can be processed at the end of marking.
5040     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5041   }
5042 
5043   // Finish up any enqueued closure apps (attributed as object copy time).
5044   buf_scan_non_heap_roots.done();
5045 
5046   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5047 
5048   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5049 
5050   double ext_root_time_ms =
5051     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5052 
5053   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5054 
5055   // During conc marking we have to filter the per-thread SATB buffers
5056   // to make sure we remove any oops into the CSet (which will show up
5057   // as implicitly live).
5058   double satb_filtering_ms = 0.0;
5059   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5060     if (mark_in_progress()) {
5061       double satb_filter_start = os::elapsedTime();
5062 
5063       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5064 
5065       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5066     }
5067   }
5068   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5069 
5070   // Now scan the complement of the collection set.
5071   if (scan_rs != NULL) {
5072     g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5073   }
5074   _process_strong_tasks->all_tasks_completed();
5075 }
5076 
5077 void
5078 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5079   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5080   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5081 }
5082 
5083 // Weak Reference Processing support
5084 
5085 // An always "is_alive" closure that is used to preserve referents.
5086 // If the object is non-null then it's alive.  Used in the preservation
5087 // of referent objects that are pointed to by reference objects
5088 // discovered by the CM ref processor.
5089 class G1AlwaysAliveClosure: public BoolObjectClosure {
5090   G1CollectedHeap* _g1;
5091 public:
5092   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5093   bool do_object_b(oop p) {
5094     if (p != NULL) {
5095       return true;
5096     }
5097     return false;
5098   }
5099 };
5100 
5101 bool G1STWIsAliveClosure::do_object_b(oop p) {
5102   // An object is reachable if it is outside the collection set,
5103   // or is inside and copied.
5104   return !_g1->obj_in_cs(p) || p->is_forwarded();
5105 }
5106 
5107 // Non Copying Keep Alive closure
5108 class G1KeepAliveClosure: public OopClosure {
5109   G1CollectedHeap* _g1;
5110 public:
5111   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5112   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5113   void do_oop(      oop* p) {
5114     oop obj = *p;
5115 
5116     if (_g1->obj_in_cs(obj)) {
5117       assert( obj->is_forwarded(), "invariant" );
5118       *p = obj->forwardee();
5119     }
5120   }
5121 };
5122 
5123 // Copying Keep Alive closure - can be called from both
5124 // serial and parallel code as long as different worker
5125 // threads utilize different G1ParScanThreadState instances
5126 // and different queues.
5127 
5128 class G1CopyingKeepAliveClosure: public OopClosure {
5129   G1CollectedHeap*         _g1h;
5130   OopClosure*              _copy_non_heap_obj_cl;
5131   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5132   G1ParScanThreadState*    _par_scan_state;
5133 
5134 public:
5135   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5136                             OopClosure* non_heap_obj_cl,
5137                             OopsInHeapRegionClosure* metadata_obj_cl,
5138                             G1ParScanThreadState* pss):
5139     _g1h(g1h),
5140     _copy_non_heap_obj_cl(non_heap_obj_cl),
5141     _copy_metadata_obj_cl(metadata_obj_cl),
5142     _par_scan_state(pss)
5143   {}
5144 
5145   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5146   virtual void do_oop(      oop* p) { do_oop_work(p); }
5147 
5148   template <class T> void do_oop_work(T* p) {
5149     oop obj = oopDesc::load_decode_heap_oop(p);
5150 
5151     if (_g1h->obj_in_cs(obj)) {
5152       // If the referent object has been forwarded (either copied
5153       // to a new location or to itself in the event of an
5154       // evacuation failure) then we need to update the reference
5155       // field and, if both reference and referent are in the G1
5156       // heap, update the RSet for the referent.
5157       //
5158       // If the referent has not been forwarded then we have to keep
5159       // it alive by policy. Therefore we have copy the referent.
5160       //
5161       // If the reference field is in the G1 heap then we can push
5162       // on the PSS queue. When the queue is drained (after each
5163       // phase of reference processing) the object and it's followers
5164       // will be copied, the reference field set to point to the
5165       // new location, and the RSet updated. Otherwise we need to
5166       // use the the non-heap or metadata closures directly to copy
5167       // the refernt object and update the pointer, while avoiding
5168       // updating the RSet.
5169 
5170       if (_g1h->is_in_g1_reserved(p)) {
5171         _par_scan_state->push_on_queue(p);
5172       } else {
5173         assert(!ClassLoaderDataGraph::contains((address)p),
5174                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5175                               PTR_FORMAT, p));
5176           _copy_non_heap_obj_cl->do_oop(p);
5177         }
5178       }
5179     }
5180 };
5181 
5182 // Serial drain queue closure. Called as the 'complete_gc'
5183 // closure for each discovered list in some of the
5184 // reference processing phases.
5185 
5186 class G1STWDrainQueueClosure: public VoidClosure {
5187 protected:
5188   G1CollectedHeap* _g1h;
5189   G1ParScanThreadState* _par_scan_state;
5190 
5191   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5192 
5193 public:
5194   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5195     _g1h(g1h),
5196     _par_scan_state(pss)
5197   { }
5198 
5199   void do_void() {
5200     G1ParScanThreadState* const pss = par_scan_state();
5201     pss->trim_queue();
5202   }
5203 };
5204 
5205 // Parallel Reference Processing closures
5206 
5207 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5208 // processing during G1 evacuation pauses.
5209 
5210 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5211 private:
5212   G1CollectedHeap*   _g1h;
5213   RefToScanQueueSet* _queues;
5214   FlexibleWorkGang*  _workers;
5215   int                _active_workers;
5216 
5217 public:
5218   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5219                         FlexibleWorkGang* workers,
5220                         RefToScanQueueSet *task_queues,
5221                         int n_workers) :
5222     _g1h(g1h),
5223     _queues(task_queues),
5224     _workers(workers),
5225     _active_workers(n_workers)
5226   {
5227     assert(n_workers > 0, "shouldn't call this otherwise");
5228   }
5229 
5230   // Executes the given task using concurrent marking worker threads.
5231   virtual void execute(ProcessTask& task);
5232   virtual void execute(EnqueueTask& task);
5233 };
5234 
5235 // Gang task for possibly parallel reference processing
5236 
5237 class G1STWRefProcTaskProxy: public AbstractGangTask {
5238   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5239   ProcessTask&     _proc_task;
5240   G1CollectedHeap* _g1h;
5241   RefToScanQueueSet *_task_queues;
5242   ParallelTaskTerminator* _terminator;
5243 
5244 public:
5245   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5246                      G1CollectedHeap* g1h,
5247                      RefToScanQueueSet *task_queues,
5248                      ParallelTaskTerminator* terminator) :
5249     AbstractGangTask("Process reference objects in parallel"),
5250     _proc_task(proc_task),
5251     _g1h(g1h),
5252     _task_queues(task_queues),
5253     _terminator(terminator)
5254   {}
5255 
5256   virtual void work(uint worker_id) {
5257     // The reference processing task executed by a single worker.
5258     ResourceMark rm;
5259     HandleMark   hm;
5260 
5261     G1STWIsAliveClosure is_alive(_g1h);
5262 
5263     G1ParScanThreadState pss(_g1h, worker_id);
5264 
5265     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5266     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5267     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5268 
5269     pss.set_evac_closure(&scan_evac_cl);
5270     pss.set_evac_failure_closure(&evac_failure_cl);
5271     pss.set_partial_scan_closure(&partial_scan_cl);
5272 
5273     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5274     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5275 
5276     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5277     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5278 
5279     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5280     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5281 
5282     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5283       // We also need to mark copied objects.
5284       copy_non_heap_cl = &copy_mark_non_heap_cl;
5285       copy_metadata_cl = &copy_mark_metadata_cl;
5286     }
5287 
5288     // Keep alive closure.
5289     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5290 
5291     // Complete GC closure
5292     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5293 
5294     // Call the reference processing task's work routine.
5295     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5296 
5297     // Note we cannot assert that the refs array is empty here as not all
5298     // of the processing tasks (specifically phase2 - pp2_work) execute
5299     // the complete_gc closure (which ordinarily would drain the queue) so
5300     // the queue may not be empty.
5301   }
5302 };
5303 
5304 // Driver routine for parallel reference processing.
5305 // Creates an instance of the ref processing gang
5306 // task and has the worker threads execute it.
5307 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5308   assert(_workers != NULL, "Need parallel worker threads.");
5309 
5310   ParallelTaskTerminator terminator(_active_workers, _queues);
5311   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5312 
5313   _g1h->set_par_threads(_active_workers);
5314   _workers->run_task(&proc_task_proxy);
5315   _g1h->set_par_threads(0);
5316 }
5317 
5318 // Gang task for parallel reference enqueueing.
5319 
5320 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5321   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5322   EnqueueTask& _enq_task;
5323 
5324 public:
5325   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5326     AbstractGangTask("Enqueue reference objects in parallel"),
5327     _enq_task(enq_task)
5328   { }
5329 
5330   virtual void work(uint worker_id) {
5331     _enq_task.work(worker_id);
5332   }
5333 };
5334 
5335 // Driver routine for parallel reference enqueing.
5336 // Creates an instance of the ref enqueueing gang
5337 // task and has the worker threads execute it.
5338 
5339 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5340   assert(_workers != NULL, "Need parallel worker threads.");
5341 
5342   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5343 
5344   _g1h->set_par_threads(_active_workers);
5345   _workers->run_task(&enq_task_proxy);
5346   _g1h->set_par_threads(0);
5347 }
5348 
5349 // End of weak reference support closures
5350 
5351 // Abstract task used to preserve (i.e. copy) any referent objects
5352 // that are in the collection set and are pointed to by reference
5353 // objects discovered by the CM ref processor.
5354 
5355 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5356 protected:
5357   G1CollectedHeap* _g1h;
5358   RefToScanQueueSet      *_queues;
5359   ParallelTaskTerminator _terminator;
5360   uint _n_workers;
5361 
5362 public:
5363   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5364     AbstractGangTask("ParPreserveCMReferents"),
5365     _g1h(g1h),
5366     _queues(task_queues),
5367     _terminator(workers, _queues),
5368     _n_workers(workers)
5369   { }
5370 
5371   void work(uint worker_id) {
5372     ResourceMark rm;
5373     HandleMark   hm;
5374 
5375     G1ParScanThreadState            pss(_g1h, worker_id);
5376     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5377     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5378     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5379 
5380     pss.set_evac_closure(&scan_evac_cl);
5381     pss.set_evac_failure_closure(&evac_failure_cl);
5382     pss.set_partial_scan_closure(&partial_scan_cl);
5383 
5384     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5385 
5386 
5387     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5388     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5389 
5390     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5391     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5392 
5393     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5394     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5395 
5396     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5397       // We also need to mark copied objects.
5398       copy_non_heap_cl = &copy_mark_non_heap_cl;
5399       copy_metadata_cl = &copy_mark_metadata_cl;
5400     }
5401 
5402     // Is alive closure
5403     G1AlwaysAliveClosure always_alive(_g1h);
5404 
5405     // Copying keep alive closure. Applied to referent objects that need
5406     // to be copied.
5407     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5408 
5409     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5410 
5411     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5412     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5413 
5414     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5415     // So this must be true - but assert just in case someone decides to
5416     // change the worker ids.
5417     assert(0 <= worker_id && worker_id < limit, "sanity");
5418     assert(!rp->discovery_is_atomic(), "check this code");
5419 
5420     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5421     for (uint idx = worker_id; idx < limit; idx += stride) {
5422       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5423 
5424       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5425       while (iter.has_next()) {
5426         // Since discovery is not atomic for the CM ref processor, we
5427         // can see some null referent objects.
5428         iter.load_ptrs(DEBUG_ONLY(true));
5429         oop ref = iter.obj();
5430 
5431         // This will filter nulls.
5432         if (iter.is_referent_alive()) {
5433           iter.make_referent_alive();
5434         }
5435         iter.move_to_next();
5436       }
5437     }
5438 
5439     // Drain the queue - which may cause stealing
5440     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5441     drain_queue.do_void();
5442     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5443     assert(pss.refs()->is_empty(), "should be");
5444   }
5445 };
5446 
5447 // Weak Reference processing during an evacuation pause (part 1).
5448 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5449   double ref_proc_start = os::elapsedTime();
5450 
5451   ReferenceProcessor* rp = _ref_processor_stw;
5452   assert(rp->discovery_enabled(), "should have been enabled");
5453 
5454   // Any reference objects, in the collection set, that were 'discovered'
5455   // by the CM ref processor should have already been copied (either by
5456   // applying the external root copy closure to the discovered lists, or
5457   // by following an RSet entry).
5458   //
5459   // But some of the referents, that are in the collection set, that these
5460   // reference objects point to may not have been copied: the STW ref
5461   // processor would have seen that the reference object had already
5462   // been 'discovered' and would have skipped discovering the reference,
5463   // but would not have treated the reference object as a regular oop.
5464   // As a reult the copy closure would not have been applied to the
5465   // referent object.
5466   //
5467   // We need to explicitly copy these referent objects - the references
5468   // will be processed at the end of remarking.
5469   //
5470   // We also need to do this copying before we process the reference
5471   // objects discovered by the STW ref processor in case one of these
5472   // referents points to another object which is also referenced by an
5473   // object discovered by the STW ref processor.
5474 
5475   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5476            no_of_gc_workers == workers()->active_workers(),
5477            "Need to reset active GC workers");
5478 
5479   set_par_threads(no_of_gc_workers);
5480   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5481                                                  no_of_gc_workers,
5482                                                  _task_queues);
5483 
5484   if (G1CollectedHeap::use_parallel_gc_threads()) {
5485     workers()->run_task(&keep_cm_referents);
5486   } else {
5487     keep_cm_referents.work(0);
5488   }
5489 
5490   set_par_threads(0);
5491 
5492   // Closure to test whether a referent is alive.
5493   G1STWIsAliveClosure is_alive(this);
5494 
5495   // Even when parallel reference processing is enabled, the processing
5496   // of JNI refs is serial and performed serially by the current thread
5497   // rather than by a worker. The following PSS will be used for processing
5498   // JNI refs.
5499 
5500   // Use only a single queue for this PSS.
5501   G1ParScanThreadState pss(this, 0);
5502 
5503   // We do not embed a reference processor in the copying/scanning
5504   // closures while we're actually processing the discovered
5505   // reference objects.
5506   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5507   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5508   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5509 
5510   pss.set_evac_closure(&scan_evac_cl);
5511   pss.set_evac_failure_closure(&evac_failure_cl);
5512   pss.set_partial_scan_closure(&partial_scan_cl);
5513 
5514   assert(pss.refs()->is_empty(), "pre-condition");
5515 
5516   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5517   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5518 
5519   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5520   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5521 
5522   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5523   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5524 
5525   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5526     // We also need to mark copied objects.
5527     copy_non_heap_cl = &copy_mark_non_heap_cl;
5528     copy_metadata_cl = &copy_mark_metadata_cl;
5529   }
5530 
5531   // Keep alive closure.
5532   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5533 
5534   // Serial Complete GC closure
5535   G1STWDrainQueueClosure drain_queue(this, &pss);
5536 
5537   // Setup the soft refs policy...
5538   rp->setup_policy(false);
5539 
5540   if (!rp->processing_is_mt()) {
5541     // Serial reference processing...
5542     rp->process_discovered_references(&is_alive,
5543                                       &keep_alive,
5544                                       &drain_queue,
5545                                       NULL);
5546   } else {
5547     // Parallel reference processing
5548     assert(rp->num_q() == no_of_gc_workers, "sanity");
5549     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5550 
5551     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5552     rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5553   }
5554 
5555   // We have completed copying any necessary live referent objects
5556   // (that were not copied during the actual pause) so we can
5557   // retire any active alloc buffers
5558   pss.retire_alloc_buffers();
5559   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5560 
5561   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5562   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5563 }
5564 
5565 // Weak Reference processing during an evacuation pause (part 2).
5566 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5567   double ref_enq_start = os::elapsedTime();
5568 
5569   ReferenceProcessor* rp = _ref_processor_stw;
5570   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5571 
5572   // Now enqueue any remaining on the discovered lists on to
5573   // the pending list.
5574   if (!rp->processing_is_mt()) {
5575     // Serial reference processing...
5576     rp->enqueue_discovered_references();
5577   } else {
5578     // Parallel reference enqueuing
5579 
5580     assert(no_of_gc_workers == workers()->active_workers(),
5581            "Need to reset active workers");
5582     assert(rp->num_q() == no_of_gc_workers, "sanity");
5583     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5584 
5585     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5586     rp->enqueue_discovered_references(&par_task_executor);
5587   }
5588 
5589   rp->verify_no_references_recorded();
5590   assert(!rp->discovery_enabled(), "should have been disabled");
5591 
5592   // FIXME
5593   // CM's reference processing also cleans up the string and symbol tables.
5594   // Should we do that here also? We could, but it is a serial operation
5595   // and could signicantly increase the pause time.
5596 
5597   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5598   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5599 }
5600 
5601 void G1CollectedHeap::evacuate_collection_set() {
5602   _expand_heap_after_alloc_failure = true;
5603   set_evacuation_failed(false);
5604 
5605   // Should G1EvacuationFailureALot be in effect for this GC?
5606   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5607 
5608   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5609 
5610   // Disable the hot card cache.
5611   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5612   hot_card_cache->reset_hot_cache_claimed_index();
5613   hot_card_cache->set_use_cache(false);
5614 
5615   uint n_workers;
5616   if (G1CollectedHeap::use_parallel_gc_threads()) {
5617     n_workers =
5618       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5619                                      workers()->active_workers(),
5620                                      Threads::number_of_non_daemon_threads());
5621     assert(UseDynamicNumberOfGCThreads ||
5622            n_workers == workers()->total_workers(),
5623            "If not dynamic should be using all the  workers");
5624     workers()->set_active_workers(n_workers);
5625     set_par_threads(n_workers);
5626   } else {
5627     assert(n_par_threads() == 0,
5628            "Should be the original non-parallel value");
5629     n_workers = 1;
5630   }
5631 
5632   G1ParTask g1_par_task(this, _task_queues);
5633 
5634   init_for_evac_failure(NULL);
5635 
5636   rem_set()->prepare_for_younger_refs_iterate(true);
5637 
5638   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5639   double start_par_time_sec = os::elapsedTime();
5640   double end_par_time_sec;
5641 
5642   {
5643     StrongRootsScope srs(this);
5644 
5645     if (G1CollectedHeap::use_parallel_gc_threads()) {
5646       // The individual threads will set their evac-failure closures.
5647       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5648       // These tasks use ShareHeap::_process_strong_tasks
5649       assert(UseDynamicNumberOfGCThreads ||
5650              workers()->active_workers() == workers()->total_workers(),
5651              "If not dynamic should be using all the  workers");
5652       workers()->run_task(&g1_par_task);
5653     } else {
5654       g1_par_task.set_for_termination(n_workers);
5655       g1_par_task.work(0);
5656     }
5657     end_par_time_sec = os::elapsedTime();
5658 
5659     // Closing the inner scope will execute the destructor
5660     // for the StrongRootsScope object. We record the current
5661     // elapsed time before closing the scope so that time
5662     // taken for the SRS destructor is NOT included in the
5663     // reported parallel time.
5664   }
5665 
5666   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5667   g1_policy()->phase_times()->record_par_time(par_time_ms);
5668 
5669   double code_root_fixup_time_ms =
5670         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5671   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5672 
5673   set_par_threads(0);
5674 
5675   // Process any discovered reference objects - we have
5676   // to do this _before_ we retire the GC alloc regions
5677   // as we may have to copy some 'reachable' referent
5678   // objects (and their reachable sub-graphs) that were
5679   // not copied during the pause.
5680   process_discovered_references(n_workers);
5681 
5682   // Weak root processing.
5683   // Note: when JSR 292 is enabled and code blobs can contain
5684   // non-perm oops then we will need to process the code blobs
5685   // here too.
5686   {
5687     G1STWIsAliveClosure is_alive(this);
5688     G1KeepAliveClosure keep_alive(this);
5689     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5690   }
5691 
5692   release_gc_alloc_regions(n_workers);
5693   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5694 
5695   // Reset and re-enable the hot card cache.
5696   // Note the counts for the cards in the regions in the
5697   // collection set are reset when the collection set is freed.
5698   hot_card_cache->reset_hot_cache();
5699   hot_card_cache->set_use_cache(true);
5700 
5701   finalize_for_evac_failure();
5702 
5703   if (evacuation_failed()) {
5704     remove_self_forwarding_pointers();
5705 
5706     // Reset the G1EvacuationFailureALot counters and flags
5707     // Note: the values are reset only when an actual
5708     // evacuation failure occurs.
5709     NOT_PRODUCT(reset_evacuation_should_fail();)
5710   }
5711 
5712   // Enqueue any remaining references remaining on the STW
5713   // reference processor's discovered lists. We need to do
5714   // this after the card table is cleaned (and verified) as
5715   // the act of enqueuing entries on to the pending list
5716   // will log these updates (and dirty their associated
5717   // cards). We need these updates logged to update any
5718   // RSets.
5719   enqueue_discovered_references(n_workers);
5720 
5721   if (G1DeferredRSUpdate) {
5722     RedirtyLoggedCardTableEntryFastClosure redirty;
5723     dirty_card_queue_set().set_closure(&redirty);
5724     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5725 
5726     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5727     dcq.merge_bufferlists(&dirty_card_queue_set());
5728     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5729   }
5730   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5731 }
5732 
5733 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5734                                      size_t* pre_used,
5735                                      FreeRegionList* free_list,
5736                                      OldRegionSet* old_proxy_set,
5737                                      HumongousRegionSet* humongous_proxy_set,
5738                                      HRRSCleanupTask* hrrs_cleanup_task,
5739                                      bool par) {
5740   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5741     if (hr->isHumongous()) {
5742       assert(hr->startsHumongous(), "we should only see starts humongous");
5743       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5744     } else {
5745       _old_set.remove_with_proxy(hr, old_proxy_set);
5746       free_region(hr, pre_used, free_list, par);
5747     }
5748   } else {
5749     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5750   }
5751 }
5752 
5753 void G1CollectedHeap::free_region(HeapRegion* hr,
5754                                   size_t* pre_used,
5755                                   FreeRegionList* free_list,
5756                                   bool par) {
5757   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5758   assert(!hr->is_empty(), "the region should not be empty");
5759   assert(free_list != NULL, "pre-condition");
5760 
5761   // Clear the card counts for this region.
5762   // Note: we only need to do this if the region is not young
5763   // (since we don't refine cards in young regions).
5764   if (!hr->is_young()) {
5765     _cg1r->hot_card_cache()->reset_card_counts(hr);
5766   }
5767   *pre_used += hr->used();
5768   hr->hr_clear(par, true /* clear_space */);
5769   free_list->add_as_head(hr);
5770 }
5771 
5772 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5773                                      size_t* pre_used,
5774                                      FreeRegionList* free_list,
5775                                      HumongousRegionSet* humongous_proxy_set,
5776                                      bool par) {
5777   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5778   assert(free_list != NULL, "pre-condition");
5779   assert(humongous_proxy_set != NULL, "pre-condition");
5780 
5781   size_t hr_used = hr->used();
5782   size_t hr_capacity = hr->capacity();
5783   size_t hr_pre_used = 0;
5784   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5785   // We need to read this before we make the region non-humongous,
5786   // otherwise the information will be gone.
5787   uint last_index = hr->last_hc_index();
5788   hr->set_notHumongous();
5789   free_region(hr, &hr_pre_used, free_list, par);
5790 
5791   uint i = hr->hrs_index() + 1;
5792   while (i < last_index) {
5793     HeapRegion* curr_hr = region_at(i);
5794     assert(curr_hr->continuesHumongous(), "invariant");
5795     curr_hr->set_notHumongous();
5796     free_region(curr_hr, &hr_pre_used, free_list, par);
5797     i += 1;
5798   }
5799   assert(hr_pre_used == hr_used,
5800          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5801                  "should be the same", hr_pre_used, hr_used));
5802   *pre_used += hr_pre_used;
5803 }
5804 
5805 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5806                                        FreeRegionList* free_list,
5807                                        OldRegionSet* old_proxy_set,
5808                                        HumongousRegionSet* humongous_proxy_set,
5809                                        bool par) {
5810   if (pre_used > 0) {
5811     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5812     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5813     assert(_summary_bytes_used >= pre_used,
5814            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5815                    "should be >= pre_used: "SIZE_FORMAT,
5816                    _summary_bytes_used, pre_used));
5817     _summary_bytes_used -= pre_used;
5818   }
5819   if (free_list != NULL && !free_list->is_empty()) {
5820     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5821     _free_list.add_as_head(free_list);
5822   }
5823   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5824     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5825     _old_set.update_from_proxy(old_proxy_set);
5826   }
5827   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5828     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5829     _humongous_set.update_from_proxy(humongous_proxy_set);
5830   }
5831 }
5832 
5833 class G1ParCleanupCTTask : public AbstractGangTask {
5834   CardTableModRefBS* _ct_bs;
5835   G1CollectedHeap* _g1h;
5836   HeapRegion* volatile _su_head;
5837 public:
5838   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5839                      G1CollectedHeap* g1h) :
5840     AbstractGangTask("G1 Par Cleanup CT Task"),
5841     _ct_bs(ct_bs), _g1h(g1h) { }
5842 
5843   void work(uint worker_id) {
5844     HeapRegion* r;
5845     while (r = _g1h->pop_dirty_cards_region()) {
5846       clear_cards(r);
5847     }
5848   }
5849 
5850   void clear_cards(HeapRegion* r) {
5851     // Cards of the survivors should have already been dirtied.
5852     if (!r->is_survivor()) {
5853       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5854     }
5855   }
5856 };
5857 
5858 #ifndef PRODUCT
5859 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5860   G1CollectedHeap* _g1h;
5861   CardTableModRefBS* _ct_bs;
5862 public:
5863   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5864     : _g1h(g1h), _ct_bs(ct_bs) { }
5865   virtual bool doHeapRegion(HeapRegion* r) {
5866     if (r->is_survivor()) {
5867       _g1h->verify_dirty_region(r);
5868     } else {
5869       _g1h->verify_not_dirty_region(r);
5870     }
5871     return false;
5872   }
5873 };
5874 
5875 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5876   // All of the region should be clean.
5877   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5878   MemRegion mr(hr->bottom(), hr->end());
5879   ct_bs->verify_not_dirty_region(mr);
5880 }
5881 
5882 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5883   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5884   // dirty allocated blocks as they allocate them. The thread that
5885   // retires each region and replaces it with a new one will do a
5886   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5887   // not dirty that area (one less thing to have to do while holding
5888   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5889   // is dirty.
5890   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5891   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5892   ct_bs->verify_dirty_region(mr);
5893 }
5894 
5895 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5896   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5897   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5898     verify_dirty_region(hr);
5899   }
5900 }
5901 
5902 void G1CollectedHeap::verify_dirty_young_regions() {
5903   verify_dirty_young_list(_young_list->first_region());
5904 }
5905 #endif
5906 
5907 void G1CollectedHeap::cleanUpCardTable() {
5908   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5909   double start = os::elapsedTime();
5910 
5911   {
5912     // Iterate over the dirty cards region list.
5913     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5914 
5915     if (G1CollectedHeap::use_parallel_gc_threads()) {
5916       set_par_threads();
5917       workers()->run_task(&cleanup_task);
5918       set_par_threads(0);
5919     } else {
5920       while (_dirty_cards_region_list) {
5921         HeapRegion* r = _dirty_cards_region_list;
5922         cleanup_task.clear_cards(r);
5923         _dirty_cards_region_list = r->get_next_dirty_cards_region();
5924         if (_dirty_cards_region_list == r) {
5925           // The last region.
5926           _dirty_cards_region_list = NULL;
5927         }
5928         r->set_next_dirty_cards_region(NULL);
5929       }
5930     }
5931 #ifndef PRODUCT
5932     if (G1VerifyCTCleanup || VerifyAfterGC) {
5933       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5934       heap_region_iterate(&cleanup_verifier);
5935     }
5936 #endif
5937   }
5938 
5939   double elapsed = os::elapsedTime() - start;
5940   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5941 }
5942 
5943 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5944   size_t pre_used = 0;
5945   FreeRegionList local_free_list("Local List for CSet Freeing");
5946 
5947   double young_time_ms     = 0.0;
5948   double non_young_time_ms = 0.0;
5949 
5950   // Since the collection set is a superset of the the young list,
5951   // all we need to do to clear the young list is clear its
5952   // head and length, and unlink any young regions in the code below
5953   _young_list->clear();
5954 
5955   G1CollectorPolicy* policy = g1_policy();
5956 
5957   double start_sec = os::elapsedTime();
5958   bool non_young = true;
5959 
5960   HeapRegion* cur = cs_head;
5961   int age_bound = -1;
5962   size_t rs_lengths = 0;
5963 
5964   while (cur != NULL) {
5965     assert(!is_on_master_free_list(cur), "sanity");
5966     if (non_young) {
5967       if (cur->is_young()) {
5968         double end_sec = os::elapsedTime();
5969         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5970         non_young_time_ms += elapsed_ms;
5971 
5972         start_sec = os::elapsedTime();
5973         non_young = false;
5974       }
5975     } else {
5976       if (!cur->is_young()) {
5977         double end_sec = os::elapsedTime();
5978         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5979         young_time_ms += elapsed_ms;
5980 
5981         start_sec = os::elapsedTime();
5982         non_young = true;
5983       }
5984     }
5985 
5986     rs_lengths += cur->rem_set()->occupied();
5987 
5988     HeapRegion* next = cur->next_in_collection_set();
5989     assert(cur->in_collection_set(), "bad CS");
5990     cur->set_next_in_collection_set(NULL);
5991     cur->set_in_collection_set(false);
5992 
5993     if (cur->is_young()) {
5994       int index = cur->young_index_in_cset();
5995       assert(index != -1, "invariant");
5996       assert((uint) index < policy->young_cset_region_length(), "invariant");
5997       size_t words_survived = _surviving_young_words[index];
5998       cur->record_surv_words_in_group(words_survived);
5999 
6000       // At this point the we have 'popped' cur from the collection set
6001       // (linked via next_in_collection_set()) but it is still in the
6002       // young list (linked via next_young_region()). Clear the
6003       // _next_young_region field.
6004       cur->set_next_young_region(NULL);
6005     } else {
6006       int index = cur->young_index_in_cset();
6007       assert(index == -1, "invariant");
6008     }
6009 
6010     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6011             (!cur->is_young() && cur->young_index_in_cset() == -1),
6012             "invariant" );
6013 
6014     if (!cur->evacuation_failed()) {
6015       MemRegion used_mr = cur->used_region();
6016 
6017       // And the region is empty.
6018       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6019       free_region(cur, &pre_used, &local_free_list, false /* par */);
6020     } else {
6021       cur->uninstall_surv_rate_group();
6022       if (cur->is_young()) {
6023         cur->set_young_index_in_cset(-1);
6024       }
6025       cur->set_not_young();
6026       cur->set_evacuation_failed(false);
6027       // The region is now considered to be old.
6028       _old_set.add(cur);
6029     }
6030     cur = next;
6031   }
6032 
6033   policy->record_max_rs_lengths(rs_lengths);
6034   policy->cset_regions_freed();
6035 
6036   double end_sec = os::elapsedTime();
6037   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6038 
6039   if (non_young) {
6040     non_young_time_ms += elapsed_ms;
6041   } else {
6042     young_time_ms += elapsed_ms;
6043   }
6044 
6045   update_sets_after_freeing_regions(pre_used, &local_free_list,
6046                                     NULL /* old_proxy_set */,
6047                                     NULL /* humongous_proxy_set */,
6048                                     false /* par */);
6049   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6050   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6051 }
6052 
6053 // This routine is similar to the above but does not record
6054 // any policy statistics or update free lists; we are abandoning
6055 // the current incremental collection set in preparation of a
6056 // full collection. After the full GC we will start to build up
6057 // the incremental collection set again.
6058 // This is only called when we're doing a full collection
6059 // and is immediately followed by the tearing down of the young list.
6060 
6061 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6062   HeapRegion* cur = cs_head;
6063 
6064   while (cur != NULL) {
6065     HeapRegion* next = cur->next_in_collection_set();
6066     assert(cur->in_collection_set(), "bad CS");
6067     cur->set_next_in_collection_set(NULL);
6068     cur->set_in_collection_set(false);
6069     cur->set_young_index_in_cset(-1);
6070     cur = next;
6071   }
6072 }
6073 
6074 void G1CollectedHeap::set_free_regions_coming() {
6075   if (G1ConcRegionFreeingVerbose) {
6076     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6077                            "setting free regions coming");
6078   }
6079 
6080   assert(!free_regions_coming(), "pre-condition");
6081   _free_regions_coming = true;
6082 }
6083 
6084 void G1CollectedHeap::reset_free_regions_coming() {
6085   assert(free_regions_coming(), "pre-condition");
6086 
6087   {
6088     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6089     _free_regions_coming = false;
6090     SecondaryFreeList_lock->notify_all();
6091   }
6092 
6093   if (G1ConcRegionFreeingVerbose) {
6094     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6095                            "reset free regions coming");
6096   }
6097 }
6098 
6099 void G1CollectedHeap::wait_while_free_regions_coming() {
6100   // Most of the time we won't have to wait, so let's do a quick test
6101   // first before we take the lock.
6102   if (!free_regions_coming()) {
6103     return;
6104   }
6105 
6106   if (G1ConcRegionFreeingVerbose) {
6107     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6108                            "waiting for free regions");
6109   }
6110 
6111   {
6112     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6113     while (free_regions_coming()) {
6114       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6115     }
6116   }
6117 
6118   if (G1ConcRegionFreeingVerbose) {
6119     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6120                            "done waiting for free regions");
6121   }
6122 }
6123 
6124 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6125   assert(heap_lock_held_for_gc(),
6126               "the heap lock should already be held by or for this thread");
6127   _young_list->push_region(hr);
6128 }
6129 
6130 class NoYoungRegionsClosure: public HeapRegionClosure {
6131 private:
6132   bool _success;
6133 public:
6134   NoYoungRegionsClosure() : _success(true) { }
6135   bool doHeapRegion(HeapRegion* r) {
6136     if (r->is_young()) {
6137       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6138                              r->bottom(), r->end());
6139       _success = false;
6140     }
6141     return false;
6142   }
6143   bool success() { return _success; }
6144 };
6145 
6146 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6147   bool ret = _young_list->check_list_empty(check_sample);
6148 
6149   if (check_heap) {
6150     NoYoungRegionsClosure closure;
6151     heap_region_iterate(&closure);
6152     ret = ret && closure.success();
6153   }
6154 
6155   return ret;
6156 }
6157 
6158 class TearDownRegionSetsClosure : public HeapRegionClosure {
6159 private:
6160   OldRegionSet *_old_set;
6161 
6162 public:
6163   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6164 
6165   bool doHeapRegion(HeapRegion* r) {
6166     if (r->is_empty()) {
6167       // We ignore empty regions, we'll empty the free list afterwards
6168     } else if (r->is_young()) {
6169       // We ignore young regions, we'll empty the young list afterwards
6170     } else if (r->isHumongous()) {
6171       // We ignore humongous regions, we're not tearing down the
6172       // humongous region set
6173     } else {
6174       // The rest should be old
6175       _old_set->remove(r);
6176     }
6177     return false;
6178   }
6179 
6180   ~TearDownRegionSetsClosure() {
6181     assert(_old_set->is_empty(), "post-condition");
6182   }
6183 };
6184 
6185 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6186   assert_at_safepoint(true /* should_be_vm_thread */);
6187 
6188   if (!free_list_only) {
6189     TearDownRegionSetsClosure cl(&_old_set);
6190     heap_region_iterate(&cl);
6191 
6192     // Need to do this after the heap iteration to be able to
6193     // recognize the young regions and ignore them during the iteration.
6194     _young_list->empty_list();
6195   }
6196   _free_list.remove_all();
6197 }
6198 
6199 class RebuildRegionSetsClosure : public HeapRegionClosure {
6200 private:
6201   bool            _free_list_only;
6202   OldRegionSet*   _old_set;
6203   FreeRegionList* _free_list;
6204   size_t          _total_used;
6205 
6206 public:
6207   RebuildRegionSetsClosure(bool free_list_only,
6208                            OldRegionSet* old_set, FreeRegionList* free_list) :
6209     _free_list_only(free_list_only),
6210     _old_set(old_set), _free_list(free_list), _total_used(0) {
6211     assert(_free_list->is_empty(), "pre-condition");
6212     if (!free_list_only) {
6213       assert(_old_set->is_empty(), "pre-condition");
6214     }
6215   }
6216 
6217   bool doHeapRegion(HeapRegion* r) {
6218     if (r->continuesHumongous()) {
6219       return false;
6220     }
6221 
6222     if (r->is_empty()) {
6223       // Add free regions to the free list
6224       _free_list->add_as_tail(r);
6225     } else if (!_free_list_only) {
6226       assert(!r->is_young(), "we should not come across young regions");
6227 
6228       if (r->isHumongous()) {
6229         // We ignore humongous regions, we left the humongous set unchanged
6230       } else {
6231         // The rest should be old, add them to the old set
6232         _old_set->add(r);
6233       }
6234       _total_used += r->used();
6235     }
6236 
6237     return false;
6238   }
6239 
6240   size_t total_used() {
6241     return _total_used;
6242   }
6243 };
6244 
6245 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6246   assert_at_safepoint(true /* should_be_vm_thread */);
6247 
6248   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6249   heap_region_iterate(&cl);
6250 
6251   if (!free_list_only) {
6252     _summary_bytes_used = cl.total_used();
6253   }
6254   assert(_summary_bytes_used == recalculate_used(),
6255          err_msg("inconsistent _summary_bytes_used, "
6256                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6257                  _summary_bytes_used, recalculate_used()));
6258 }
6259 
6260 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6261   _refine_cte_cl->set_concurrent(concurrent);
6262 }
6263 
6264 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6265   HeapRegion* hr = heap_region_containing(p);
6266   if (hr == NULL) {
6267     return false;
6268   } else {
6269     return hr->is_in(p);
6270   }
6271 }
6272 
6273 // Methods for the mutator alloc region
6274 
6275 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6276                                                       bool force) {
6277   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6278   assert(!force || g1_policy()->can_expand_young_list(),
6279          "if force is true we should be able to expand the young list");
6280   bool young_list_full = g1_policy()->is_young_list_full();
6281   if (force || !young_list_full) {
6282     HeapRegion* new_alloc_region = new_region(word_size,
6283                                               false /* do_expand */);
6284     if (new_alloc_region != NULL) {
6285       set_region_short_lived_locked(new_alloc_region);
6286       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6287       return new_alloc_region;
6288     }
6289   }
6290   return NULL;
6291 }
6292 
6293 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6294                                                   size_t allocated_bytes) {
6295   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6296   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6297 
6298   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6299   _summary_bytes_used += allocated_bytes;
6300   _hr_printer.retire(alloc_region);
6301   // We update the eden sizes here, when the region is retired,
6302   // instead of when it's allocated, since this is the point that its
6303   // used space has been recored in _summary_bytes_used.
6304   g1mm()->update_eden_size();
6305 }
6306 
6307 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6308                                                     bool force) {
6309   return _g1h->new_mutator_alloc_region(word_size, force);
6310 }
6311 
6312 void G1CollectedHeap::set_par_threads() {
6313   // Don't change the number of workers.  Use the value previously set
6314   // in the workgroup.
6315   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6316   uint n_workers = workers()->active_workers();
6317   assert(UseDynamicNumberOfGCThreads ||
6318            n_workers == workers()->total_workers(),
6319       "Otherwise should be using the total number of workers");
6320   if (n_workers == 0) {
6321     assert(false, "Should have been set in prior evacuation pause.");
6322     n_workers = ParallelGCThreads;
6323     workers()->set_active_workers(n_workers);
6324   }
6325   set_par_threads(n_workers);
6326 }
6327 
6328 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6329                                        size_t allocated_bytes) {
6330   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6331 }
6332 
6333 // Methods for the GC alloc regions
6334 
6335 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6336                                                  uint count,
6337                                                  GCAllocPurpose ap) {
6338   assert(FreeList_lock->owned_by_self(), "pre-condition");
6339 
6340   if (count < g1_policy()->max_regions(ap)) {
6341     HeapRegion* new_alloc_region = new_region(word_size,
6342                                               true /* do_expand */);
6343     if (new_alloc_region != NULL) {
6344       // We really only need to do this for old regions given that we
6345       // should never scan survivors. But it doesn't hurt to do it
6346       // for survivors too.
6347       new_alloc_region->set_saved_mark();
6348       if (ap == GCAllocForSurvived) {
6349         new_alloc_region->set_survivor();
6350         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6351       } else {
6352         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6353       }
6354       bool during_im = g1_policy()->during_initial_mark_pause();
6355       new_alloc_region->note_start_of_copying(during_im);
6356       return new_alloc_region;
6357     } else {
6358       g1_policy()->note_alloc_region_limit_reached(ap);
6359     }
6360   }
6361   return NULL;
6362 }
6363 
6364 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6365                                              size_t allocated_bytes,
6366                                              GCAllocPurpose ap) {
6367   bool during_im = g1_policy()->during_initial_mark_pause();
6368   alloc_region->note_end_of_copying(during_im);
6369   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6370   if (ap == GCAllocForSurvived) {
6371     young_list()->add_survivor_region(alloc_region);
6372   } else {
6373     _old_set.add(alloc_region);
6374   }
6375   _hr_printer.retire(alloc_region);
6376 }
6377 
6378 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6379                                                        bool force) {
6380   assert(!force, "not supported for GC alloc regions");
6381   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6382 }
6383 
6384 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6385                                           size_t allocated_bytes) {
6386   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6387                                GCAllocForSurvived);
6388 }
6389 
6390 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6391                                                   bool force) {
6392   assert(!force, "not supported for GC alloc regions");
6393   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6394 }
6395 
6396 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6397                                      size_t allocated_bytes) {
6398   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6399                                GCAllocForTenured);
6400 }
6401 // Heap region set verification
6402 
6403 class VerifyRegionListsClosure : public HeapRegionClosure {
6404 private:
6405   FreeRegionList*     _free_list;
6406   OldRegionSet*       _old_set;
6407   HumongousRegionSet* _humongous_set;
6408   uint                _region_count;
6409 
6410 public:
6411   VerifyRegionListsClosure(OldRegionSet* old_set,
6412                            HumongousRegionSet* humongous_set,
6413                            FreeRegionList* free_list) :
6414     _old_set(old_set), _humongous_set(humongous_set),
6415     _free_list(free_list), _region_count(0) { }
6416 
6417   uint region_count() { return _region_count; }
6418 
6419   bool doHeapRegion(HeapRegion* hr) {
6420     _region_count += 1;
6421 
6422     if (hr->continuesHumongous()) {
6423       return false;
6424     }
6425 
6426     if (hr->is_young()) {
6427       // TODO
6428     } else if (hr->startsHumongous()) {
6429       _humongous_set->verify_next_region(hr);
6430     } else if (hr->is_empty()) {
6431       _free_list->verify_next_region(hr);
6432     } else {
6433       _old_set->verify_next_region(hr);
6434     }
6435     return false;
6436   }
6437 };
6438 
6439 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6440                                              HeapWord* bottom) {
6441   HeapWord* end = bottom + HeapRegion::GrainWords;
6442   MemRegion mr(bottom, end);
6443   assert(_g1_reserved.contains(mr), "invariant");
6444   // This might return NULL if the allocation fails
6445   return new HeapRegion(hrs_index, _bot_shared, mr);
6446 }
6447 
6448 void G1CollectedHeap::verify_region_sets() {
6449   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6450 
6451   // First, check the explicit lists.
6452   _free_list.verify();
6453   {
6454     // Given that a concurrent operation might be adding regions to
6455     // the secondary free list we have to take the lock before
6456     // verifying it.
6457     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6458     _secondary_free_list.verify();
6459   }
6460   _old_set.verify();
6461   _humongous_set.verify();
6462 
6463   // If a concurrent region freeing operation is in progress it will
6464   // be difficult to correctly attributed any free regions we come
6465   // across to the correct free list given that they might belong to
6466   // one of several (free_list, secondary_free_list, any local lists,
6467   // etc.). So, if that's the case we will skip the rest of the
6468   // verification operation. Alternatively, waiting for the concurrent
6469   // operation to complete will have a non-trivial effect on the GC's
6470   // operation (no concurrent operation will last longer than the
6471   // interval between two calls to verification) and it might hide
6472   // any issues that we would like to catch during testing.
6473   if (free_regions_coming()) {
6474     return;
6475   }
6476 
6477   // Make sure we append the secondary_free_list on the free_list so
6478   // that all free regions we will come across can be safely
6479   // attributed to the free_list.
6480   append_secondary_free_list_if_not_empty_with_lock();
6481 
6482   // Finally, make sure that the region accounting in the lists is
6483   // consistent with what we see in the heap.
6484   _old_set.verify_start();
6485   _humongous_set.verify_start();
6486   _free_list.verify_start();
6487 
6488   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6489   heap_region_iterate(&cl);
6490 
6491   _old_set.verify_end();
6492   _humongous_set.verify_end();
6493   _free_list.verify_end();
6494 }