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       verify_after_gc();
1421 
1422       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1423       ref_processor_stw()->verify_no_references_recorded();
1424 
1425       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1426       ClassLoaderDataGraph::purge();
1427     MetaspaceAux::verify_metrics();
1428 
1429       // Note: since we've just done a full GC, concurrent
1430       // marking is no longer active. Therefore we need not
1431       // re-enable reference discovery for the CM ref processor.
1432       // That will be done at the start of the next marking cycle.
1433       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1434       ref_processor_cm()->verify_no_references_recorded();
1435 
1436       reset_gc_time_stamp();
1437       // Since everything potentially moved, we will clear all remembered
1438       // sets, and clear all cards.  Later we will rebuild remebered
1439       // sets. We will also reset the GC time stamps of the regions.
1440       clear_rsets_post_compaction();
1441       check_gc_time_stamps();
1442 
1443       // Resize the heap if necessary.
1444       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1445 
1446       if (_hr_printer.is_active()) {
1447         // We should do this after we potentially resize the heap so
1448         // that all the COMMIT / UNCOMMIT events are generated before
1449         // the end GC event.
1450 
1451         print_hrs_post_compaction();
1452         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1453       }
1454 
1455       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1456       if (hot_card_cache->use_cache()) {
1457         hot_card_cache->reset_card_counts();
1458         hot_card_cache->reset_hot_cache();
1459       }
1460 
1461       // Rebuild remembered sets of all regions.
1462       if (G1CollectedHeap::use_parallel_gc_threads()) {
1463         uint n_workers =
1464           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1465                                                   workers()->active_workers(),
1466                                                   Threads::number_of_non_daemon_threads());
1467         assert(UseDynamicNumberOfGCThreads ||
1468                n_workers == workers()->total_workers(),
1469                "If not dynamic should be using all the  workers");
1470         workers()->set_active_workers(n_workers);
1471         // Set parallel threads in the heap (_n_par_threads) only
1472         // before a parallel phase and always reset it to 0 after
1473         // the phase so that the number of parallel threads does
1474         // no get carried forward to a serial phase where there
1475         // may be code that is "possibly_parallel".
1476         set_par_threads(n_workers);
1477 
1478         ParRebuildRSTask rebuild_rs_task(this);
1479         assert(check_heap_region_claim_values(
1480                HeapRegion::InitialClaimValue), "sanity check");
1481         assert(UseDynamicNumberOfGCThreads ||
1482                workers()->active_workers() == workers()->total_workers(),
1483                "Unless dynamic should use total workers");
1484         // Use the most recent number of  active workers
1485         assert(workers()->active_workers() > 0,
1486                "Active workers not properly set");
1487         set_par_threads(workers()->active_workers());
1488         workers()->run_task(&rebuild_rs_task);
1489         set_par_threads(0);
1490         assert(check_heap_region_claim_values(
1491                HeapRegion::RebuildRSClaimValue), "sanity check");
1492         reset_heap_region_claim_values();
1493       } else {
1494         RebuildRSOutOfRegionClosure rebuild_rs(this);
1495         heap_region_iterate(&rebuild_rs);
1496       }
1497 
1498       if (true) { // FIXME
1499         MetaspaceGC::compute_new_size();
1500       }
1501 
1502 #ifdef TRACESPINNING
1503       ParallelTaskTerminator::print_termination_counts();
1504 #endif
1505 
1506       // Discard all rset updates
1507       JavaThread::dirty_card_queue_set().abandon_logs();
1508       assert(!G1DeferredRSUpdate
1509              || (G1DeferredRSUpdate &&
1510                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1511 
1512       _young_list->reset_sampled_info();
1513       // At this point there should be no regions in the
1514       // entire heap tagged as young.
1515       assert(check_young_list_empty(true /* check_heap */),
1516              "young list should be empty at this point");
1517 
1518       // Update the number of full collections that have been completed.
1519       increment_old_marking_cycles_completed(false /* concurrent */);
1520 
1521       _hrs.verify_optional();
1522       verify_region_sets_optional();
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();
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, "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_deleted = 0;
1850   MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1851   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1852   assert(mr.end() == old_end, "post-condition");
1853 
1854   ergo_verbose3(ErgoHeapSizing,
1855                 "shrink the heap",
1856                 ergo_format_byte("requested shrinking amount")
1857                 ergo_format_byte("aligned shrinking amount")
1858                 ergo_format_byte("attempted shrinking amount"),
1859                 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1860   if (mr.byte_size() > 0) {
1861     if (_hr_printer.is_active()) {
1862       HeapWord* curr = mr.end();
1863       while (curr > mr.start()) {
1864         HeapWord* curr_end = curr;
1865         curr -= HeapRegion::GrainWords;
1866         _hr_printer.uncommit(curr, curr_end);
1867       }
1868       assert(curr == mr.start(), "post-condition");
1869     }
1870 
1871     _g1_storage.shrink_by(mr.byte_size());
1872     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1873     assert(mr.start() == new_end, "post-condition");
1874 
1875     _expansion_regions += num_regions_deleted;
1876     update_committed_space(old_end, new_end);
1877     HeapRegionRemSet::shrink_heap(n_regions());
1878     g1_policy()->record_new_heap_size(n_regions());
1879   } else {
1880     ergo_verbose0(ErgoHeapSizing,
1881                   "did not shrink the heap",
1882                   ergo_format_reason("heap shrinking operation failed"));
1883   }
1884 }
1885 
1886 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1887   verify_region_sets_optional();
1888 
1889   // We should only reach here at the end of a Full GC which means we
1890   // should not not be holding to any GC alloc regions. The method
1891   // below will make sure of that and do any remaining clean up.
1892   abandon_gc_alloc_regions();
1893 
1894   // Instead of tearing down / rebuilding the free lists here, we
1895   // could instead use the remove_all_pending() method on free_list to
1896   // remove only the ones that we need to remove.
1897   tear_down_region_sets(true /* free_list_only */);
1898   shrink_helper(shrink_bytes);
1899   rebuild_region_sets(true /* free_list_only */);
1900 
1901   _hrs.verify_optional();
1902   verify_region_sets_optional();
1903 }
1904 
1905 // Public methods.
1906 
1907 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1908 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1909 #endif // _MSC_VER
1910 
1911 
1912 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1913   SharedHeap(policy_),
1914   _g1_policy(policy_),
1915   _dirty_card_queue_set(false),
1916   _into_cset_dirty_card_queue_set(false),
1917   _is_alive_closure_cm(this),
1918   _is_alive_closure_stw(this),
1919   _ref_processor_cm(NULL),
1920   _ref_processor_stw(NULL),
1921   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1922   _bot_shared(NULL),
1923   _evac_failure_scan_stack(NULL) ,
1924   _mark_in_progress(false),
1925   _cg1r(NULL), _summary_bytes_used(0),
1926   _g1mm(NULL),
1927   _refine_cte_cl(NULL),
1928   _full_collection(false),
1929   _free_list("Master Free List"),
1930   _secondary_free_list("Secondary Free List"),
1931   _old_set("Old Set"),
1932   _humongous_set("Master Humongous Set"),
1933   _free_regions_coming(false),
1934   _young_list(new YoungList(this)),
1935   _gc_time_stamp(0),
1936   _retained_old_gc_alloc_region(NULL),
1937   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1938   _old_plab_stats(OldPLABSize, PLABWeight),
1939   _expand_heap_after_alloc_failure(true),
1940   _surviving_young_words(NULL),
1941   _old_marking_cycles_started(0),
1942   _old_marking_cycles_completed(0),
1943   _in_cset_fast_test(NULL),
1944   _in_cset_fast_test_base(NULL),
1945   _dirty_cards_region_list(NULL),
1946   _worker_cset_start_region(NULL),
1947   _worker_cset_start_region_time_stamp(NULL) {
1948   _g1h = this; // To catch bugs.
1949   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1950     vm_exit_during_initialization("Failed necessary allocation.");
1951   }
1952 
1953   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1954 
1955   int n_queues = MAX2((int)ParallelGCThreads, 1);
1956   _task_queues = new RefToScanQueueSet(n_queues);
1957 
1958   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1959   assert(n_rem_sets > 0, "Invariant.");
1960 
1961   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1962   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1963 
1964   for (int i = 0; i < n_queues; i++) {
1965     RefToScanQueue* q = new RefToScanQueue();
1966     q->initialize();
1967     _task_queues->register_queue(i, q);
1968   }
1969 
1970   clear_cset_start_regions();
1971 
1972   // Initialize the G1EvacuationFailureALot counters and flags.
1973   NOT_PRODUCT(reset_evacuation_should_fail();)
1974 
1975   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1976 }
1977 
1978 jint G1CollectedHeap::initialize() {
1979   CollectedHeap::pre_initialize();
1980   os::enable_vtime();
1981 
1982   G1Log::init();
1983 
1984   // Necessary to satisfy locking discipline assertions.
1985 
1986   MutexLocker x(Heap_lock);
1987 
1988   // We have to initialize the printer before committing the heap, as
1989   // it will be used then.
1990   _hr_printer.set_active(G1PrintHeapRegions);
1991 
1992   // While there are no constraints in the GC code that HeapWordSize
1993   // be any particular value, there are multiple other areas in the
1994   // system which believe this to be true (e.g. oop->object_size in some
1995   // cases incorrectly returns the size in wordSize units rather than
1996   // HeapWordSize).
1997   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1998 
1999   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2000   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2001 
2002   // Ensure that the sizes are properly aligned.
2003   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2004   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2005 
2006   _cg1r = new ConcurrentG1Refine(this);
2007 
2008   // Reserve the maximum.
2009 
2010   // When compressed oops are enabled, the preferred heap base
2011   // is calculated by subtracting the requested size from the
2012   // 32Gb boundary and using the result as the base address for
2013   // heap reservation. If the requested size is not aligned to
2014   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2015   // into the ReservedHeapSpace constructor) then the actual
2016   // base of the reserved heap may end up differing from the
2017   // address that was requested (i.e. the preferred heap base).
2018   // If this happens then we could end up using a non-optimal
2019   // compressed oops mode.
2020 
2021   // Since max_byte_size is aligned to the size of a heap region (checked
2022   // above).
2023   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2024 
2025   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2026                                                  HeapRegion::GrainBytes);
2027 
2028   // It is important to do this in a way such that concurrent readers can't
2029   // temporarily think somethings in the heap.  (I've actually seen this
2030   // happen in asserts: DLD.)
2031   _reserved.set_word_size(0);
2032   _reserved.set_start((HeapWord*)heap_rs.base());
2033   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2034 
2035   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2036 
2037   // Create the gen rem set (and barrier set) for the entire reserved region.
2038   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2039   set_barrier_set(rem_set()->bs());
2040   if (barrier_set()->is_a(BarrierSet::ModRef)) {
2041     _mr_bs = (ModRefBarrierSet*)_barrier_set;
2042   } else {
2043     vm_exit_during_initialization("G1 requires a mod ref bs.");
2044     return JNI_ENOMEM;
2045   }
2046 
2047   // Also create a G1 rem set.
2048   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2049     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2050   } else {
2051     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2052     return JNI_ENOMEM;
2053   }
2054 
2055   // Carve out the G1 part of the heap.
2056 
2057   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2058   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2059                            g1_rs.size()/HeapWordSize);
2060 
2061   _g1_storage.initialize(g1_rs, 0);
2062   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2063   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2064                   (HeapWord*) _g1_reserved.end(),
2065                   _expansion_regions);
2066   
2067   // Do later initialization work for concurrent refinement.
2068   _cg1r->init();
2069 
2070   // 6843694 - ensure that the maximum region index can fit
2071   // in the remembered set structures.
2072   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2073   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2074 
2075   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2076   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2077   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2078             "too many cards per region");
2079 
2080   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2081 
2082   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2083                                              heap_word_size(init_byte_size));
2084 
2085   _g1h = this;
2086 
2087   _in_cset_fast_test_length = max_regions();
2088   _in_cset_fast_test_base =
2089                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2090 
2091   // We're biasing _in_cset_fast_test to avoid subtracting the
2092   // beginning of the heap every time we want to index; basically
2093   // it's the same with what we do with the card table.
2094   _in_cset_fast_test = _in_cset_fast_test_base -
2095                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2096 
2097   // Clear the _cset_fast_test bitmap in anticipation of adding
2098   // regions to the incremental collection set for the first
2099   // evacuation pause.
2100   clear_cset_fast_test();
2101 
2102   // Create the ConcurrentMark data structure and thread.
2103   // (Must do this late, so that "max_regions" is defined.)
2104   _cm = new ConcurrentMark(this, heap_rs);
2105   if (_cm == NULL || !_cm->completed_initialization()) {
2106     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2107     return JNI_ENOMEM;
2108   }
2109   _cmThread = _cm->cmThread();
2110 
2111   // Initialize the from_card cache structure of HeapRegionRemSet.
2112   HeapRegionRemSet::init_heap(max_regions());
2113 
2114   // Now expand into the initial heap size.
2115   if (!expand(init_byte_size)) {
2116     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2117     return JNI_ENOMEM;
2118   }
2119 
2120   // Perform any initialization actions delegated to the policy.
2121   g1_policy()->init();
2122 
2123   _refine_cte_cl =
2124     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2125                                     g1_rem_set(),
2126                                     concurrent_g1_refine());
2127   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2128 
2129   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2130                                                SATB_Q_FL_lock,
2131                                                G1SATBProcessCompletedThreshold,
2132                                                Shared_SATB_Q_lock);
2133 
2134   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2135                                                 DirtyCardQ_FL_lock,
2136                                                 concurrent_g1_refine()->yellow_zone(),
2137                                                 concurrent_g1_refine()->red_zone(),
2138                                                 Shared_DirtyCardQ_lock);
2139 
2140   if (G1DeferredRSUpdate) {
2141     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2142                                       DirtyCardQ_FL_lock,
2143                                       -1, // never trigger processing
2144                                       -1, // no limit on length
2145                                       Shared_DirtyCardQ_lock,
2146                                       &JavaThread::dirty_card_queue_set());
2147   }
2148 
2149   // Initialize the card queue set used to hold cards containing
2150   // references into the collection set.
2151   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2152                                              DirtyCardQ_FL_lock,
2153                                              -1, // never trigger processing
2154                                              -1, // no limit on length
2155                                              Shared_DirtyCardQ_lock,
2156                                              &JavaThread::dirty_card_queue_set());
2157 
2158   // In case we're keeping closure specialization stats, initialize those
2159   // counts and that mechanism.
2160   SpecializationStats::clear();
2161 
2162   // Here we allocate the dummy full region that is required by the
2163   // G1AllocRegion class. If we don't pass an address in the reserved
2164   // space here, lots of asserts fire.
2165 
2166   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2167                                              _g1_reserved.start());
2168   // We'll re-use the same region whether the alloc region will
2169   // require BOT updates or not and, if it doesn't, then a non-young
2170   // region will complain that it cannot support allocations without
2171   // BOT updates. So we'll tag the dummy region as young to avoid that.
2172   dummy_region->set_young();
2173   // Make sure it's full.
2174   dummy_region->set_top(dummy_region->end());
2175   G1AllocRegion::setup(this, dummy_region);
2176 
2177   init_mutator_alloc_region();
2178 
2179   // Do create of the monitoring and management support so that
2180   // values in the heap have been properly initialized.
2181   _g1mm = new G1MonitoringSupport(this);
2182 
2183   return JNI_OK;
2184 }
2185 
2186 void G1CollectedHeap::ref_processing_init() {
2187   // Reference processing in G1 currently works as follows:
2188   //
2189   // * There are two reference processor instances. One is
2190   //   used to record and process discovered references
2191   //   during concurrent marking; the other is used to
2192   //   record and process references during STW pauses
2193   //   (both full and incremental).
2194   // * Both ref processors need to 'span' the entire heap as
2195   //   the regions in the collection set may be dotted around.
2196   //
2197   // * For the concurrent marking ref processor:
2198   //   * Reference discovery is enabled at initial marking.
2199   //   * Reference discovery is disabled and the discovered
2200   //     references processed etc during remarking.
2201   //   * Reference discovery is MT (see below).
2202   //   * Reference discovery requires a barrier (see below).
2203   //   * Reference processing may or may not be MT
2204   //     (depending on the value of ParallelRefProcEnabled
2205   //     and ParallelGCThreads).
2206   //   * A full GC disables reference discovery by the CM
2207   //     ref processor and abandons any entries on it's
2208   //     discovered lists.
2209   //
2210   // * For the STW processor:
2211   //   * Non MT discovery is enabled at the start of a full GC.
2212   //   * Processing and enqueueing during a full GC is non-MT.
2213   //   * During a full GC, references are processed after marking.
2214   //
2215   //   * Discovery (may or may not be MT) is enabled at the start
2216   //     of an incremental evacuation pause.
2217   //   * References are processed near the end of a STW evacuation pause.
2218   //   * For both types of GC:
2219   //     * Discovery is atomic - i.e. not concurrent.
2220   //     * Reference discovery will not need a barrier.
2221 
2222   SharedHeap::ref_processing_init();
2223   MemRegion mr = reserved_region();
2224 
2225   // Concurrent Mark ref processor
2226   _ref_processor_cm =
2227     new ReferenceProcessor(mr,    // span
2228                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2229                                 // mt processing
2230                            (int) ParallelGCThreads,
2231                                 // degree of mt processing
2232                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2233                                 // mt discovery
2234                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2235                                 // degree of mt discovery
2236                            false,
2237                                 // Reference discovery is not atomic
2238                            &_is_alive_closure_cm,
2239                                 // is alive closure
2240                                 // (for efficiency/performance)
2241                            true);
2242                                 // Setting next fields of discovered
2243                                 // lists requires a barrier.
2244 
2245   // STW ref processor
2246   _ref_processor_stw =
2247     new ReferenceProcessor(mr,    // span
2248                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2249                                 // mt processing
2250                            MAX2((int)ParallelGCThreads, 1),
2251                                 // degree of mt processing
2252                            (ParallelGCThreads > 1),
2253                                 // mt discovery
2254                            MAX2((int)ParallelGCThreads, 1),
2255                                 // degree of mt discovery
2256                            true,
2257                                 // Reference discovery is atomic
2258                            &_is_alive_closure_stw,
2259                                 // is alive closure
2260                                 // (for efficiency/performance)
2261                            false);
2262                                 // Setting next fields of discovered
2263                                 // lists requires a barrier.
2264 }
2265 
2266 size_t G1CollectedHeap::capacity() const {
2267   return _g1_committed.byte_size();
2268 }
2269 
2270 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2271   assert(!hr->continuesHumongous(), "pre-condition");
2272   hr->reset_gc_time_stamp();
2273   if (hr->startsHumongous()) {
2274     uint first_index = hr->hrs_index() + 1;
2275     uint last_index = hr->last_hc_index();
2276     for (uint i = first_index; i < last_index; i += 1) {
2277       HeapRegion* chr = region_at(i);
2278       assert(chr->continuesHumongous(), "sanity");
2279       chr->reset_gc_time_stamp();
2280     }
2281   }
2282 }
2283 
2284 #ifndef PRODUCT
2285 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2286 private:
2287   unsigned _gc_time_stamp;
2288   bool _failures;
2289 
2290 public:
2291   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2292     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2293 
2294   virtual bool doHeapRegion(HeapRegion* hr) {
2295     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2296     if (_gc_time_stamp != region_gc_time_stamp) {
2297       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2298                              "expected %d", HR_FORMAT_PARAMS(hr),
2299                              region_gc_time_stamp, _gc_time_stamp);
2300       _failures = true;
2301     }
2302     return false;
2303   }
2304 
2305   bool failures() { return _failures; }
2306 };
2307 
2308 void G1CollectedHeap::check_gc_time_stamps() {
2309   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2310   heap_region_iterate(&cl);
2311   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2312 }
2313 #endif // PRODUCT
2314 
2315 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2316                                                  DirtyCardQueue* into_cset_dcq,
2317                                                  bool concurrent,
2318                                                  int worker_i) {
2319   // Clean cards in the hot card cache
2320   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2321   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2322 
2323   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2324   int n_completed_buffers = 0;
2325   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2326     n_completed_buffers++;
2327   }
2328   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2329   dcqs.clear_n_completed_buffers();
2330   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2331 }
2332 
2333 
2334 // Computes the sum of the storage used by the various regions.
2335 
2336 size_t G1CollectedHeap::used() const {
2337   assert(Heap_lock->owner() != NULL,
2338          "Should be owned on this thread's behalf.");
2339   size_t result = _summary_bytes_used;
2340   // Read only once in case it is set to NULL concurrently
2341   HeapRegion* hr = _mutator_alloc_region.get();
2342   if (hr != NULL)
2343     result += hr->used();
2344   return result;
2345 }
2346 
2347 size_t G1CollectedHeap::used_unlocked() const {
2348   size_t result = _summary_bytes_used;
2349   return result;
2350 }
2351 
2352 class SumUsedClosure: public HeapRegionClosure {
2353   size_t _used;
2354 public:
2355   SumUsedClosure() : _used(0) {}
2356   bool doHeapRegion(HeapRegion* r) {
2357     if (!r->continuesHumongous()) {
2358       _used += r->used();
2359     }
2360     return false;
2361   }
2362   size_t result() { return _used; }
2363 };
2364 
2365 size_t G1CollectedHeap::recalculate_used() const {
2366   SumUsedClosure blk;
2367   heap_region_iterate(&blk);
2368   return blk.result();
2369 }
2370 
2371 size_t G1CollectedHeap::unsafe_max_alloc() {
2372   if (free_regions() > 0) return HeapRegion::GrainBytes;
2373   // otherwise, is there space in the current allocation region?
2374 
2375   // We need to store the current allocation region in a local variable
2376   // here. The problem is that this method doesn't take any locks and
2377   // there may be other threads which overwrite the current allocation
2378   // region field. attempt_allocation(), for example, sets it to NULL
2379   // and this can happen *after* the NULL check here but before the call
2380   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2381   // to be a problem in the optimized build, since the two loads of the
2382   // current allocation region field are optimized away.
2383   HeapRegion* hr = _mutator_alloc_region.get();
2384   if (hr == NULL) {
2385     return 0;
2386   }
2387   return hr->free();
2388 }
2389 
2390 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2391   switch (cause) {
2392     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2393     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2394     case GCCause::_g1_humongous_allocation: return true;
2395     default:                                return false;
2396   }
2397 }
2398 
2399 #ifndef PRODUCT
2400 void G1CollectedHeap::allocate_dummy_regions() {
2401   // Let's fill up most of the region
2402   size_t word_size = HeapRegion::GrainWords - 1024;
2403   // And as a result the region we'll allocate will be humongous.
2404   guarantee(isHumongous(word_size), "sanity");
2405 
2406   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2407     // Let's use the existing mechanism for the allocation
2408     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2409     if (dummy_obj != NULL) {
2410       MemRegion mr(dummy_obj, word_size);
2411       CollectedHeap::fill_with_object(mr);
2412     } else {
2413       // If we can't allocate once, we probably cannot allocate
2414       // again. Let's get out of the loop.
2415       break;
2416     }
2417   }
2418 }
2419 #endif // !PRODUCT
2420 
2421 void G1CollectedHeap::increment_old_marking_cycles_started() {
2422   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2423     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2424     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2425     _old_marking_cycles_started, _old_marking_cycles_completed));
2426 
2427   _old_marking_cycles_started++;
2428 }
2429 
2430 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2431   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2432 
2433   // We assume that if concurrent == true, then the caller is a
2434   // concurrent thread that was joined the Suspendible Thread
2435   // Set. If there's ever a cheap way to check this, we should add an
2436   // assert here.
2437 
2438   // Given that this method is called at the end of a Full GC or of a
2439   // concurrent cycle, and those can be nested (i.e., a Full GC can
2440   // interrupt a concurrent cycle), the number of full collections
2441   // completed should be either one (in the case where there was no
2442   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2443   // behind the number of full collections started.
2444 
2445   // This is the case for the inner caller, i.e. a Full GC.
2446   assert(concurrent ||
2447          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2448          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2449          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2450                  "is inconsistent with _old_marking_cycles_completed = %u",
2451                  _old_marking_cycles_started, _old_marking_cycles_completed));
2452 
2453   // This is the case for the outer caller, i.e. the concurrent cycle.
2454   assert(!concurrent ||
2455          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2456          err_msg("for outer caller (concurrent cycle): "
2457                  "_old_marking_cycles_started = %u "
2458                  "is inconsistent with _old_marking_cycles_completed = %u",
2459                  _old_marking_cycles_started, _old_marking_cycles_completed));
2460 
2461   _old_marking_cycles_completed += 1;
2462 
2463   // We need to clear the "in_progress" flag in the CM thread before
2464   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2465   // is set) so that if a waiter requests another System.gc() it doesn't
2466   // incorrectly see that a marking cyle is still in progress.
2467   if (concurrent) {
2468     _cmThread->clear_in_progress();
2469   }
2470 
2471   // This notify_all() will ensure that a thread that called
2472   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2473   // and it's waiting for a full GC to finish will be woken up. It is
2474   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2475   FullGCCount_lock->notify_all();
2476 }
2477 
2478 void G1CollectedHeap::collect(GCCause::Cause cause) {
2479   assert_heap_not_locked();
2480 
2481   unsigned int gc_count_before;
2482   unsigned int old_marking_count_before;
2483   bool retry_gc;
2484 
2485   do {
2486     retry_gc = false;
2487 
2488     {
2489       MutexLocker ml(Heap_lock);
2490 
2491       // Read the GC count while holding the Heap_lock
2492       gc_count_before = total_collections();
2493       old_marking_count_before = _old_marking_cycles_started;
2494     }
2495 
2496     if (should_do_concurrent_full_gc(cause)) {
2497       // Schedule an initial-mark evacuation pause that will start a
2498       // concurrent cycle. We're setting word_size to 0 which means that
2499       // we are not requesting a post-GC allocation.
2500       VM_G1IncCollectionPause op(gc_count_before,
2501                                  0,     /* word_size */
2502                                  true,  /* should_initiate_conc_mark */
2503                                  g1_policy()->max_pause_time_ms(),
2504                                  cause);
2505 
2506       VMThread::execute(&op);
2507       if (!op.pause_succeeded()) {
2508         if (old_marking_count_before == _old_marking_cycles_started) {
2509           retry_gc = op.should_retry_gc();
2510         } else {
2511           // A Full GC happened while we were trying to schedule the
2512           // initial-mark GC. No point in starting a new cycle given
2513           // that the whole heap was collected anyway.
2514         }
2515 
2516         if (retry_gc) {
2517           if (GC_locker::is_active_and_needs_gc()) {
2518             GC_locker::stall_until_clear();
2519           }
2520         }
2521       }
2522     } else {
2523       if (cause == GCCause::_gc_locker
2524           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2525 
2526         // Schedule a standard evacuation pause. We're setting word_size
2527         // to 0 which means that we are not requesting a post-GC allocation.
2528         VM_G1IncCollectionPause op(gc_count_before,
2529                                    0,     /* word_size */
2530                                    false, /* should_initiate_conc_mark */
2531                                    g1_policy()->max_pause_time_ms(),
2532                                    cause);
2533         VMThread::execute(&op);
2534       } else {
2535         // Schedule a Full GC.
2536         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2537         VMThread::execute(&op);
2538       }
2539     }
2540   } while (retry_gc);
2541 }
2542 
2543 bool G1CollectedHeap::is_in(const void* p) const {
2544   if (_g1_committed.contains(p)) {
2545     // Given that we know that p is in the committed space,
2546     // heap_region_containing_raw() should successfully
2547     // return the containing region.
2548     HeapRegion* hr = heap_region_containing_raw(p);
2549     return hr->is_in(p);
2550   } else {
2551     return false;
2552   }
2553 }
2554 
2555 // Iteration functions.
2556 
2557 // Iterates an OopClosure over all ref-containing fields of objects
2558 // within a HeapRegion.
2559 
2560 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2561   MemRegion _mr;
2562   ExtendedOopClosure* _cl;
2563 public:
2564   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2565     : _mr(mr), _cl(cl) {}
2566   bool doHeapRegion(HeapRegion* r) {
2567     if (!r->continuesHumongous()) {
2568       r->oop_iterate(_cl);
2569     }
2570     return false;
2571   }
2572 };
2573 
2574 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2575   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2576   heap_region_iterate(&blk);
2577 }
2578 
2579 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2580   IterateOopClosureRegionClosure blk(mr, cl);
2581   heap_region_iterate(&blk);
2582 }
2583 
2584 // Iterates an ObjectClosure over all objects within a HeapRegion.
2585 
2586 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2587   ObjectClosure* _cl;
2588 public:
2589   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2590   bool doHeapRegion(HeapRegion* r) {
2591     if (! r->continuesHumongous()) {
2592       r->object_iterate(_cl);
2593     }
2594     return false;
2595   }
2596 };
2597 
2598 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2599   IterateObjectClosureRegionClosure blk(cl);
2600   heap_region_iterate(&blk);
2601 }
2602 
2603 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2604   // FIXME: is this right?
2605   guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2606 }
2607 
2608 // Calls a SpaceClosure on a HeapRegion.
2609 
2610 class SpaceClosureRegionClosure: public HeapRegionClosure {
2611   SpaceClosure* _cl;
2612 public:
2613   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2614   bool doHeapRegion(HeapRegion* r) {
2615     _cl->do_space(r);
2616     return false;
2617   }
2618 };
2619 
2620 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2621   SpaceClosureRegionClosure blk(cl);
2622   heap_region_iterate(&blk);
2623 }
2624 
2625 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2626   _hrs.iterate(cl);
2627 }
2628 
2629 void
2630 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2631                                                  uint worker_id,
2632                                                  uint no_of_par_workers,
2633                                                  jint claim_value) {
2634   const uint regions = n_regions();
2635   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2636                              no_of_par_workers :
2637                              1);
2638   assert(UseDynamicNumberOfGCThreads ||
2639          no_of_par_workers == workers()->total_workers(),
2640          "Non dynamic should use fixed number of workers");
2641   // try to spread out the starting points of the workers
2642   const HeapRegion* start_hr =
2643                         start_region_for_worker(worker_id, no_of_par_workers);
2644   const uint start_index = start_hr->hrs_index();
2645 
2646   // each worker will actually look at all regions
2647   for (uint count = 0; count < regions; ++count) {
2648     const uint index = (start_index + count) % regions;
2649     assert(0 <= index && index < regions, "sanity");
2650     HeapRegion* r = region_at(index);
2651     // we'll ignore "continues humongous" regions (we'll process them
2652     // when we come across their corresponding "start humongous"
2653     // region) and regions already claimed
2654     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2655       continue;
2656     }
2657     // OK, try to claim it
2658     if (r->claimHeapRegion(claim_value)) {
2659       // success!
2660       assert(!r->continuesHumongous(), "sanity");
2661       if (r->startsHumongous()) {
2662         // If the region is "starts humongous" we'll iterate over its
2663         // "continues humongous" first; in fact we'll do them
2664         // first. The order is important. In on case, calling the
2665         // closure on the "starts humongous" region might de-allocate
2666         // and clear all its "continues humongous" regions and, as a
2667         // result, we might end up processing them twice. So, we'll do
2668         // them first (notice: most closures will ignore them anyway) and
2669         // then we'll do the "starts humongous" region.
2670         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2671           HeapRegion* chr = region_at(ch_index);
2672 
2673           // if the region has already been claimed or it's not
2674           // "continues humongous" we're done
2675           if (chr->claim_value() == claim_value ||
2676               !chr->continuesHumongous()) {
2677             break;
2678           }
2679 
2680           // Noone should have claimed it directly. We can given
2681           // that we claimed its "starts humongous" region.
2682           assert(chr->claim_value() != claim_value, "sanity");
2683           assert(chr->humongous_start_region() == r, "sanity");
2684 
2685           if (chr->claimHeapRegion(claim_value)) {
2686             // we should always be able to claim it; noone else should
2687             // be trying to claim this region
2688 
2689             bool res2 = cl->doHeapRegion(chr);
2690             assert(!res2, "Should not abort");
2691 
2692             // Right now, this holds (i.e., no closure that actually
2693             // does something with "continues humongous" regions
2694             // clears them). We might have to weaken it in the future,
2695             // but let's leave these two asserts here for extra safety.
2696             assert(chr->continuesHumongous(), "should still be the case");
2697             assert(chr->humongous_start_region() == r, "sanity");
2698           } else {
2699             guarantee(false, "we should not reach here");
2700           }
2701         }
2702       }
2703 
2704       assert(!r->continuesHumongous(), "sanity");
2705       bool res = cl->doHeapRegion(r);
2706       assert(!res, "Should not abort");
2707     }
2708   }
2709 }
2710 
2711 class ResetClaimValuesClosure: public HeapRegionClosure {
2712 public:
2713   bool doHeapRegion(HeapRegion* r) {
2714     r->set_claim_value(HeapRegion::InitialClaimValue);
2715     return false;
2716   }
2717 };
2718 
2719 void G1CollectedHeap::reset_heap_region_claim_values() {
2720   ResetClaimValuesClosure blk;
2721   heap_region_iterate(&blk);
2722 }
2723 
2724 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2725   ResetClaimValuesClosure blk;
2726   collection_set_iterate(&blk);
2727 }
2728 
2729 #ifdef ASSERT
2730 // This checks whether all regions in the heap have the correct claim
2731 // value. I also piggy-backed on this a check to ensure that the
2732 // humongous_start_region() information on "continues humongous"
2733 // regions is correct.
2734 
2735 class CheckClaimValuesClosure : public HeapRegionClosure {
2736 private:
2737   jint _claim_value;
2738   uint _failures;
2739   HeapRegion* _sh_region;
2740 
2741 public:
2742   CheckClaimValuesClosure(jint claim_value) :
2743     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2744   bool doHeapRegion(HeapRegion* r) {
2745     if (r->claim_value() != _claim_value) {
2746       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2747                              "claim value = %d, should be %d",
2748                              HR_FORMAT_PARAMS(r),
2749                              r->claim_value(), _claim_value);
2750       ++_failures;
2751     }
2752     if (!r->isHumongous()) {
2753       _sh_region = NULL;
2754     } else if (r->startsHumongous()) {
2755       _sh_region = r;
2756     } else if (r->continuesHumongous()) {
2757       if (r->humongous_start_region() != _sh_region) {
2758         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2759                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2760                                HR_FORMAT_PARAMS(r),
2761                                r->humongous_start_region(),
2762                                _sh_region);
2763         ++_failures;
2764       }
2765     }
2766     return false;
2767   }
2768   uint failures() { return _failures; }
2769 };
2770 
2771 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2772   CheckClaimValuesClosure cl(claim_value);
2773   heap_region_iterate(&cl);
2774   return cl.failures() == 0;
2775 }
2776 
2777 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2778 private:
2779   jint _claim_value;
2780   uint _failures;
2781 
2782 public:
2783   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2784     _claim_value(claim_value), _failures(0) { }
2785 
2786   uint failures() { return _failures; }
2787 
2788   bool doHeapRegion(HeapRegion* hr) {
2789     assert(hr->in_collection_set(), "how?");
2790     assert(!hr->isHumongous(), "H-region in CSet");
2791     if (hr->claim_value() != _claim_value) {
2792       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2793                              "claim value = %d, should be %d",
2794                              HR_FORMAT_PARAMS(hr),
2795                              hr->claim_value(), _claim_value);
2796       _failures += 1;
2797     }
2798     return false;
2799   }
2800 };
2801 
2802 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2803   CheckClaimValuesInCSetHRClosure cl(claim_value);
2804   collection_set_iterate(&cl);
2805   return cl.failures() == 0;
2806 }
2807 #endif // ASSERT
2808 
2809 // Clear the cached CSet starting regions and (more importantly)
2810 // the time stamps. Called when we reset the GC time stamp.
2811 void G1CollectedHeap::clear_cset_start_regions() {
2812   assert(_worker_cset_start_region != NULL, "sanity");
2813   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2814 
2815   int n_queues = MAX2((int)ParallelGCThreads, 1);
2816   for (int i = 0; i < n_queues; i++) {
2817     _worker_cset_start_region[i] = NULL;
2818     _worker_cset_start_region_time_stamp[i] = 0;
2819   }
2820 }
2821 
2822 // Given the id of a worker, obtain or calculate a suitable
2823 // starting region for iterating over the current collection set.
2824 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2825   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2826 
2827   HeapRegion* result = NULL;
2828   unsigned gc_time_stamp = get_gc_time_stamp();
2829 
2830   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2831     // Cached starting region for current worker was set
2832     // during the current pause - so it's valid.
2833     // Note: the cached starting heap region may be NULL
2834     // (when the collection set is empty).
2835     result = _worker_cset_start_region[worker_i];
2836     assert(result == NULL || result->in_collection_set(), "sanity");
2837     return result;
2838   }
2839 
2840   // The cached entry was not valid so let's calculate
2841   // a suitable starting heap region for this worker.
2842 
2843   // We want the parallel threads to start their collection
2844   // set iteration at different collection set regions to
2845   // avoid contention.
2846   // If we have:
2847   //          n collection set regions
2848   //          p threads
2849   // Then thread t will start at region floor ((t * n) / p)
2850 
2851   result = g1_policy()->collection_set();
2852   if (G1CollectedHeap::use_parallel_gc_threads()) {
2853     uint cs_size = g1_policy()->cset_region_length();
2854     uint active_workers = workers()->active_workers();
2855     assert(UseDynamicNumberOfGCThreads ||
2856              active_workers == workers()->total_workers(),
2857              "Unless dynamic should use total workers");
2858 
2859     uint end_ind   = (cs_size * worker_i) / active_workers;
2860     uint start_ind = 0;
2861 
2862     if (worker_i > 0 &&
2863         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2864       // Previous workers starting region is valid
2865       // so let's iterate from there
2866       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2867       result = _worker_cset_start_region[worker_i - 1];
2868     }
2869 
2870     for (uint i = start_ind; i < end_ind; i++) {
2871       result = result->next_in_collection_set();
2872     }
2873   }
2874 
2875   // Note: the calculated starting heap region may be NULL
2876   // (when the collection set is empty).
2877   assert(result == NULL || result->in_collection_set(), "sanity");
2878   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2879          "should be updated only once per pause");
2880   _worker_cset_start_region[worker_i] = result;
2881   OrderAccess::storestore();
2882   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2883   return result;
2884 }
2885 
2886 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2887                                                      uint no_of_par_workers) {
2888   uint worker_num =
2889            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2890   assert(UseDynamicNumberOfGCThreads ||
2891          no_of_par_workers == workers()->total_workers(),
2892          "Non dynamic should use fixed number of workers");
2893   const uint start_index = n_regions() * worker_i / worker_num;
2894   return region_at(start_index);
2895 }
2896 
2897 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2898   HeapRegion* r = g1_policy()->collection_set();
2899   while (r != NULL) {
2900     HeapRegion* next = r->next_in_collection_set();
2901     if (cl->doHeapRegion(r)) {
2902       cl->incomplete();
2903       return;
2904     }
2905     r = next;
2906   }
2907 }
2908 
2909 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2910                                                   HeapRegionClosure *cl) {
2911   if (r == NULL) {
2912     // The CSet is empty so there's nothing to do.
2913     return;
2914   }
2915 
2916   assert(r->in_collection_set(),
2917          "Start region must be a member of the collection set.");
2918   HeapRegion* cur = r;
2919   while (cur != NULL) {
2920     HeapRegion* next = cur->next_in_collection_set();
2921     if (cl->doHeapRegion(cur) && false) {
2922       cl->incomplete();
2923       return;
2924     }
2925     cur = next;
2926   }
2927   cur = g1_policy()->collection_set();
2928   while (cur != r) {
2929     HeapRegion* next = cur->next_in_collection_set();
2930     if (cl->doHeapRegion(cur) && false) {
2931       cl->incomplete();
2932       return;
2933     }
2934     cur = next;
2935   }
2936 }
2937 
2938 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2939   return n_regions() > 0 ? region_at(0) : NULL;
2940 }
2941 
2942 
2943 Space* G1CollectedHeap::space_containing(const void* addr) const {
2944   Space* res = heap_region_containing(addr);
2945   return res;
2946 }
2947 
2948 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2949   Space* sp = space_containing(addr);
2950   if (sp != NULL) {
2951     return sp->block_start(addr);
2952   }
2953   return NULL;
2954 }
2955 
2956 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2957   Space* sp = space_containing(addr);
2958   assert(sp != NULL, "block_size of address outside of heap");
2959   return sp->block_size(addr);
2960 }
2961 
2962 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2963   Space* sp = space_containing(addr);
2964   return sp->block_is_obj(addr);
2965 }
2966 
2967 bool G1CollectedHeap::supports_tlab_allocation() const {
2968   return true;
2969 }
2970 
2971 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2972   return HeapRegion::GrainBytes;
2973 }
2974 
2975 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2976   // Return the remaining space in the cur alloc region, but not less than
2977   // the min TLAB size.
2978 
2979   // Also, this value can be at most the humongous object threshold,
2980   // since we can't allow tlabs to grow big enough to accomodate
2981   // humongous objects.
2982 
2983   HeapRegion* hr = _mutator_alloc_region.get();
2984   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2985   if (hr == NULL) {
2986     return max_tlab_size;
2987   } else {
2988     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2989   }
2990 }
2991 
2992 size_t G1CollectedHeap::max_capacity() const {
2993   return _g1_reserved.byte_size();
2994 }
2995 
2996 jlong G1CollectedHeap::millis_since_last_gc() {
2997   // assert(false, "NYI");
2998   return 0;
2999 }
3000 
3001 void G1CollectedHeap::prepare_for_verify() {
3002   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3003     ensure_parsability(false);
3004   }
3005   g1_rem_set()->prepare_for_verify();
3006 }
3007 
3008 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3009                                               VerifyOption vo) {
3010   switch (vo) {
3011   case VerifyOption_G1UsePrevMarking:
3012     return hr->obj_allocated_since_prev_marking(obj);
3013   case VerifyOption_G1UseNextMarking:
3014     return hr->obj_allocated_since_next_marking(obj);
3015   case VerifyOption_G1UseMarkWord:
3016     return false;
3017   default:
3018     ShouldNotReachHere();
3019   }
3020   return false; // keep some compilers happy
3021 }
3022 
3023 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3024   switch (vo) {
3025   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3026   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3027   case VerifyOption_G1UseMarkWord:    return NULL;
3028   default:                            ShouldNotReachHere();
3029   }
3030   return NULL; // keep some compilers happy
3031 }
3032 
3033 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3034   switch (vo) {
3035   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3036   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3037   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3038   default:                            ShouldNotReachHere();
3039   }
3040   return false; // keep some compilers happy
3041 }
3042 
3043 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3044   switch (vo) {
3045   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3046   case VerifyOption_G1UseNextMarking: return "NTAMS";
3047   case VerifyOption_G1UseMarkWord:    return "NONE";
3048   default:                            ShouldNotReachHere();
3049   }
3050   return NULL; // keep some compilers happy
3051 }
3052 
3053 class VerifyLivenessOopClosure: public OopClosure {
3054   G1CollectedHeap* _g1h;
3055   VerifyOption _vo;
3056 public:
3057   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3058     _g1h(g1h), _vo(vo)
3059   { }
3060   void do_oop(narrowOop *p) { do_oop_work(p); }
3061   void do_oop(      oop *p) { do_oop_work(p); }
3062 
3063   template <class T> void do_oop_work(T *p) {
3064     oop obj = oopDesc::load_decode_heap_oop(p);
3065     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3066               "Dead object referenced by a not dead object");
3067   }
3068 };
3069 
3070 class VerifyObjsInRegionClosure: public ObjectClosure {
3071 private:
3072   G1CollectedHeap* _g1h;
3073   size_t _live_bytes;
3074   HeapRegion *_hr;
3075   VerifyOption _vo;
3076 public:
3077   // _vo == UsePrevMarking -> use "prev" marking information,
3078   // _vo == UseNextMarking -> use "next" marking information,
3079   // _vo == UseMarkWord    -> use mark word from object header.
3080   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3081     : _live_bytes(0), _hr(hr), _vo(vo) {
3082     _g1h = G1CollectedHeap::heap();
3083   }
3084   void do_object(oop o) {
3085     VerifyLivenessOopClosure isLive(_g1h, _vo);
3086     assert(o != NULL, "Huh?");
3087     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3088       // If the object is alive according to the mark word,
3089       // then verify that the marking information agrees.
3090       // Note we can't verify the contra-positive of the
3091       // above: if the object is dead (according to the mark
3092       // word), it may not be marked, or may have been marked
3093       // but has since became dead, or may have been allocated
3094       // since the last marking.
3095       if (_vo == VerifyOption_G1UseMarkWord) {
3096         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3097       }
3098 
3099       o->oop_iterate_no_header(&isLive);
3100       if (!_hr->obj_allocated_since_prev_marking(o)) {
3101         size_t obj_size = o->size();    // Make sure we don't overflow
3102         _live_bytes += (obj_size * HeapWordSize);
3103       }
3104     }
3105   }
3106   size_t live_bytes() { return _live_bytes; }
3107 };
3108 
3109 class PrintObjsInRegionClosure : public ObjectClosure {
3110   HeapRegion *_hr;
3111   G1CollectedHeap *_g1;
3112 public:
3113   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3114     _g1 = G1CollectedHeap::heap();
3115   };
3116 
3117   void do_object(oop o) {
3118     if (o != NULL) {
3119       HeapWord *start = (HeapWord *) o;
3120       size_t word_sz = o->size();
3121       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3122                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3123                           (void*) o, word_sz,
3124                           _g1->isMarkedPrev(o),
3125                           _g1->isMarkedNext(o),
3126                           _hr->obj_allocated_since_prev_marking(o));
3127       HeapWord *end = start + word_sz;
3128       HeapWord *cur;
3129       int *val;
3130       for (cur = start; cur < end; cur++) {
3131         val = (int *) cur;
3132         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3133       }
3134     }
3135   }
3136 };
3137 
3138 class VerifyRegionClosure: public HeapRegionClosure {
3139 private:
3140   bool             _par;
3141   VerifyOption     _vo;
3142   bool             _failures;
3143 public:
3144   // _vo == UsePrevMarking -> use "prev" marking information,
3145   // _vo == UseNextMarking -> use "next" marking information,
3146   // _vo == UseMarkWord    -> use mark word from object header.
3147   VerifyRegionClosure(bool par, VerifyOption vo)
3148     : _par(par),
3149       _vo(vo),
3150       _failures(false) {}
3151 
3152   bool failures() {
3153     return _failures;
3154   }
3155 
3156   bool doHeapRegion(HeapRegion* r) {
3157     if (!r->continuesHumongous()) {
3158       bool failures = false;
3159       r->verify(_vo, &failures);
3160       if (failures) {
3161         _failures = true;
3162       } else {
3163         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3164         r->object_iterate(&not_dead_yet_cl);
3165         if (_vo != VerifyOption_G1UseNextMarking) {
3166           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3167             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3168                                    "max_live_bytes "SIZE_FORMAT" "
3169                                    "< calculated "SIZE_FORMAT,
3170                                    r->bottom(), r->end(),
3171                                    r->max_live_bytes(),
3172                                  not_dead_yet_cl.live_bytes());
3173             _failures = true;
3174           }
3175         } else {
3176           // When vo == UseNextMarking we cannot currently do a sanity
3177           // check on the live bytes as the calculation has not been
3178           // finalized yet.
3179         }
3180       }
3181     }
3182     return false; // stop the region iteration if we hit a failure
3183   }
3184 };
3185 
3186 class YoungRefCounterClosure : public OopClosure {
3187   G1CollectedHeap* _g1h;
3188   int              _count;
3189  public:
3190   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3191   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3192   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3193 
3194   int count() { return _count; }
3195   void reset_count() { _count = 0; };
3196 };
3197 
3198 class VerifyKlassClosure: public KlassClosure {
3199   YoungRefCounterClosure _young_ref_counter_closure;
3200   OopClosure *_oop_closure;
3201  public:
3202   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3203   void do_klass(Klass* k) {
3204     k->oops_do(_oop_closure);
3205 
3206     _young_ref_counter_closure.reset_count();
3207     k->oops_do(&_young_ref_counter_closure);
3208     if (_young_ref_counter_closure.count() > 0) {
3209       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3210     }
3211   }
3212 };
3213 
3214 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3215 //       pass it as the perm_blk to SharedHeap::process_strong_roots.
3216 //       When process_strong_roots stop calling perm_blk->younger_refs_iterate
3217 //       we can change this closure to extend the simpler OopClosure.
3218 class VerifyRootsClosure: public OopsInGenClosure {
3219 private:
3220   G1CollectedHeap* _g1h;
3221   VerifyOption     _vo;
3222   bool             _failures;
3223 public:
3224   // _vo == UsePrevMarking -> use "prev" marking information,
3225   // _vo == UseNextMarking -> use "next" marking information,
3226   // _vo == UseMarkWord    -> use mark word from object header.
3227   VerifyRootsClosure(VerifyOption vo) :
3228     _g1h(G1CollectedHeap::heap()),
3229     _vo(vo),
3230     _failures(false) { }
3231 
3232   bool failures() { return _failures; }
3233 
3234   template <class T> void do_oop_nv(T* p) {
3235     T heap_oop = oopDesc::load_heap_oop(p);
3236     if (!oopDesc::is_null(heap_oop)) {
3237       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3238       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3239         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3240                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3241         if (_vo == VerifyOption_G1UseMarkWord) {
3242           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3243         }
3244         obj->print_on(gclog_or_tty);
3245         _failures = true;
3246       }
3247     }
3248   }
3249 
3250   void do_oop(oop* p)       { do_oop_nv(p); }
3251   void do_oop(narrowOop* p) { do_oop_nv(p); }
3252 };
3253 
3254 // This is the task used for parallel heap verification.
3255 
3256 class G1ParVerifyTask: public AbstractGangTask {
3257 private:
3258   G1CollectedHeap* _g1h;
3259   VerifyOption     _vo;
3260   bool             _failures;
3261 
3262 public:
3263   // _vo == UsePrevMarking -> use "prev" marking information,
3264   // _vo == UseNextMarking -> use "next" marking information,
3265   // _vo == UseMarkWord    -> use mark word from object header.
3266   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3267     AbstractGangTask("Parallel verify task"),
3268     _g1h(g1h),
3269     _vo(vo),
3270     _failures(false) { }
3271 
3272   bool failures() {
3273     return _failures;
3274   }
3275 
3276   void work(uint worker_id) {
3277     HandleMark hm;
3278     VerifyRegionClosure blk(true, _vo);
3279     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3280                                           _g1h->workers()->active_workers(),
3281                                           HeapRegion::ParVerifyClaimValue);
3282     if (blk.failures()) {
3283       _failures = true;
3284     }
3285   }
3286 };
3287 
3288 void G1CollectedHeap::verify(bool silent) {
3289   verify(silent, VerifyOption_G1UsePrevMarking);
3290 }
3291 
3292 void G1CollectedHeap::verify(bool silent,
3293                              VerifyOption vo) {
3294   if (SafepointSynchronize::is_at_safepoint()) {
3295     if (!silent) { gclog_or_tty->print("Roots "); }
3296     VerifyRootsClosure rootsCl(vo);
3297 
3298     assert(Thread::current()->is_VM_thread(),
3299            "Expected to be executed serially by the VM thread at this point");
3300 
3301     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3302     VerifyKlassClosure klassCl(this, &rootsCl);
3303 
3304     // We apply the relevant closures to all the oops in the
3305     // system dictionary, the string table and the code cache.
3306     const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3307 
3308     // Need cleared claim bits for the strong roots processing
3309     ClassLoaderDataGraph::clear_claimed_marks();
3310 
3311     process_strong_roots(true,      // activate StrongRootsScope
3312                          false,     // we set "is scavenging" to false,
3313                                     // so we don't reset the dirty cards.
3314                          ScanningOption(so),  // roots scanning options
3315                          &rootsCl,
3316                          &blobsCl,
3317                          &klassCl
3318                          );
3319 
3320     bool failures = rootsCl.failures();
3321 
3322     if (vo != VerifyOption_G1UseMarkWord) {
3323       // If we're verifying during a full GC then the region sets
3324       // will have been torn down at the start of the GC. Therefore
3325       // verifying the region sets will fail. So we only verify
3326       // the region sets when not in a full GC.
3327       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3328       verify_region_sets();
3329     }
3330 
3331     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3332     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3333       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3334              "sanity check");
3335 
3336       G1ParVerifyTask task(this, vo);
3337       assert(UseDynamicNumberOfGCThreads ||
3338         workers()->active_workers() == workers()->total_workers(),
3339         "If not dynamic should be using all the workers");
3340       int n_workers = workers()->active_workers();
3341       set_par_threads(n_workers);
3342       workers()->run_task(&task);
3343       set_par_threads(0);
3344       if (task.failures()) {
3345         failures = true;
3346       }
3347 
3348       // Checks that the expected amount of parallel work was done.
3349       // The implication is that n_workers is > 0.
3350       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3351              "sanity check");
3352 
3353       reset_heap_region_claim_values();
3354 
3355       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3356              "sanity check");
3357     } else {
3358       VerifyRegionClosure blk(false, vo);
3359       heap_region_iterate(&blk);
3360       if (blk.failures()) {
3361         failures = true;
3362       }
3363     }
3364     if (!silent) gclog_or_tty->print("RemSet ");
3365     rem_set()->verify();
3366 
3367     if (failures) {
3368       gclog_or_tty->print_cr("Heap:");
3369       // It helps to have the per-region information in the output to
3370       // help us track down what went wrong. This is why we call
3371       // print_extended_on() instead of print_on().
3372       print_extended_on(gclog_or_tty);
3373       gclog_or_tty->print_cr("");
3374 #ifndef PRODUCT
3375       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3376         concurrent_mark()->print_reachable("at-verification-failure",
3377                                            vo, false /* all */);
3378       }
3379 #endif
3380       gclog_or_tty->flush();
3381     }
3382     guarantee(!failures, "there should not have been any failures");
3383   } else {
3384     if (!silent)
3385       gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3386   }
3387 }
3388 
3389 class PrintRegionClosure: public HeapRegionClosure {
3390   outputStream* _st;
3391 public:
3392   PrintRegionClosure(outputStream* st) : _st(st) {}
3393   bool doHeapRegion(HeapRegion* r) {
3394     r->print_on(_st);
3395     return false;
3396   }
3397 };
3398 
3399 void G1CollectedHeap::print_on(outputStream* st) const {
3400   st->print(" %-20s", "garbage-first heap");
3401   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3402             capacity()/K, used_unlocked()/K);
3403   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3404             _g1_storage.low_boundary(),
3405             _g1_storage.high(),
3406             _g1_storage.high_boundary());
3407   st->cr();
3408   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3409   uint young_regions = _young_list->length();
3410   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3411             (size_t) young_regions * HeapRegion::GrainBytes / K);
3412   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3413   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3414             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3415   st->cr();
3416   MetaspaceAux::print_on(st);
3417 }
3418 
3419 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3420   print_on(st);
3421 
3422   // Print the per-region information.
3423   st->cr();
3424   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3425                "HS=humongous(starts), HC=humongous(continues), "
3426                "CS=collection set, F=free, TS=gc time stamp, "
3427                "PTAMS=previous top-at-mark-start, "
3428                "NTAMS=next top-at-mark-start)");
3429   PrintRegionClosure blk(st);
3430   heap_region_iterate(&blk);
3431 }
3432 
3433 void G1CollectedHeap::print_on_error(outputStream* st) const {
3434   this->CollectedHeap::print_on_error(st);
3435 
3436   if (_cm != NULL) {
3437     st->cr();
3438     _cm->print_on_error(st);
3439   }
3440 }
3441 
3442 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3443   if (G1CollectedHeap::use_parallel_gc_threads()) {
3444     workers()->print_worker_threads_on(st);
3445   }
3446   _cmThread->print_on(st);
3447   st->cr();
3448   _cm->print_worker_threads_on(st);
3449   _cg1r->print_worker_threads_on(st);
3450 }
3451 
3452 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3453   if (G1CollectedHeap::use_parallel_gc_threads()) {
3454     workers()->threads_do(tc);
3455   }
3456   tc->do_thread(_cmThread);
3457   _cg1r->threads_do(tc);
3458 }
3459 
3460 void G1CollectedHeap::print_tracing_info() const {
3461   // We'll overload this to mean "trace GC pause statistics."
3462   if (TraceGen0Time || TraceGen1Time) {
3463     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3464     // to that.
3465     g1_policy()->print_tracing_info();
3466   }
3467   if (G1SummarizeRSetStats) {
3468     g1_rem_set()->print_summary_info();
3469   }
3470   if (G1SummarizeConcMark) {
3471     concurrent_mark()->print_summary_info();
3472   }
3473   g1_policy()->print_yg_surv_rate_info();
3474   SpecializationStats::print();
3475 }
3476 
3477 #ifndef PRODUCT
3478 // Helpful for debugging RSet issues.
3479 
3480 class PrintRSetsClosure : public HeapRegionClosure {
3481 private:
3482   const char* _msg;
3483   size_t _occupied_sum;
3484 
3485 public:
3486   bool doHeapRegion(HeapRegion* r) {
3487     HeapRegionRemSet* hrrs = r->rem_set();
3488     size_t occupied = hrrs->occupied();
3489     _occupied_sum += occupied;
3490 
3491     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3492                            HR_FORMAT_PARAMS(r));
3493     if (occupied == 0) {
3494       gclog_or_tty->print_cr("  RSet is empty");
3495     } else {
3496       hrrs->print();
3497     }
3498     gclog_or_tty->print_cr("----------");
3499     return false;
3500   }
3501 
3502   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3503     gclog_or_tty->cr();
3504     gclog_or_tty->print_cr("========================================");
3505     gclog_or_tty->print_cr(msg);
3506     gclog_or_tty->cr();
3507   }
3508 
3509   ~PrintRSetsClosure() {
3510     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3511     gclog_or_tty->print_cr("========================================");
3512     gclog_or_tty->cr();
3513   }
3514 };
3515 
3516 void G1CollectedHeap::print_cset_rsets() {
3517   PrintRSetsClosure cl("Printing CSet RSets");
3518   collection_set_iterate(&cl);
3519 }
3520 
3521 void G1CollectedHeap::print_all_rsets() {
3522   PrintRSetsClosure cl("Printing All RSets");;
3523   heap_region_iterate(&cl);
3524 }
3525 #endif // PRODUCT
3526 
3527 G1CollectedHeap* G1CollectedHeap::heap() {
3528   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3529          "not a garbage-first heap");
3530   return _g1h;
3531 }
3532 
3533 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3534   // always_do_update_barrier = false;
3535   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3536   // Call allocation profiler
3537   AllocationProfiler::iterate_since_last_gc();
3538   // Fill TLAB's and such
3539   ensure_parsability(true);
3540 }
3541 
3542 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3543   // FIXME: what is this about?
3544   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3545   // is set.
3546   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3547                         "derived pointer present"));
3548   // always_do_update_barrier = true;
3549 
3550   // We have just completed a GC. Update the soft reference
3551   // policy with the new heap occupancy
3552   Universe::update_heap_info_at_gc();
3553 }
3554 
3555 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3556                                                unsigned int gc_count_before,
3557                                                bool* succeeded) {
3558   assert_heap_not_locked_and_not_at_safepoint();
3559   g1_policy()->record_stop_world_start();
3560   VM_G1IncCollectionPause op(gc_count_before,
3561                              word_size,
3562                              false, /* should_initiate_conc_mark */
3563                              g1_policy()->max_pause_time_ms(),
3564                              GCCause::_g1_inc_collection_pause);
3565   VMThread::execute(&op);
3566 
3567   HeapWord* result = op.result();
3568   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3569   assert(result == NULL || ret_succeeded,
3570          "the result should be NULL if the VM did not succeed");
3571   *succeeded = ret_succeeded;
3572 
3573   assert_heap_not_locked();
3574   return result;
3575 }
3576 
3577 void
3578 G1CollectedHeap::doConcurrentMark() {
3579   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3580   if (!_cmThread->in_progress()) {
3581     _cmThread->set_started();
3582     CGC_lock->notify();
3583   }
3584 }
3585 
3586 size_t G1CollectedHeap::pending_card_num() {
3587   size_t extra_cards = 0;
3588   JavaThread *curr = Threads::first();
3589   while (curr != NULL) {
3590     DirtyCardQueue& dcq = curr->dirty_card_queue();
3591     extra_cards += dcq.size();
3592     curr = curr->next();
3593   }
3594   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3595   size_t buffer_size = dcqs.buffer_size();
3596   size_t buffer_num = dcqs.completed_buffers_num();
3597 
3598   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3599   // in bytes - not the number of 'entries'. We need to convert
3600   // into a number of cards.
3601   return (buffer_size * buffer_num + extra_cards) / oopSize;
3602 }
3603 
3604 size_t G1CollectedHeap::cards_scanned() {
3605   return g1_rem_set()->cardsScanned();
3606 }
3607 
3608 void
3609 G1CollectedHeap::setup_surviving_young_words() {
3610   assert(_surviving_young_words == NULL, "pre-condition");
3611   uint array_length = g1_policy()->young_cset_region_length();
3612   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3613   if (_surviving_young_words == NULL) {
3614     vm_exit_out_of_memory(sizeof(size_t) * array_length,
3615                           "Not enough space for young surv words summary.");
3616   }
3617   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3618 #ifdef ASSERT
3619   for (uint i = 0;  i < array_length; ++i) {
3620     assert( _surviving_young_words[i] == 0, "memset above" );
3621   }
3622 #endif // !ASSERT
3623 }
3624 
3625 void
3626 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3627   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3628   uint array_length = g1_policy()->young_cset_region_length();
3629   for (uint i = 0; i < array_length; ++i) {
3630     _surviving_young_words[i] += surv_young_words[i];
3631   }
3632 }
3633 
3634 void
3635 G1CollectedHeap::cleanup_surviving_young_words() {
3636   guarantee( _surviving_young_words != NULL, "pre-condition" );
3637   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3638   _surviving_young_words = NULL;
3639 }
3640 
3641 #ifdef ASSERT
3642 class VerifyCSetClosure: public HeapRegionClosure {
3643 public:
3644   bool doHeapRegion(HeapRegion* hr) {
3645     // Here we check that the CSet region's RSet is ready for parallel
3646     // iteration. The fields that we'll verify are only manipulated
3647     // when the region is part of a CSet and is collected. Afterwards,
3648     // we reset these fields when we clear the region's RSet (when the
3649     // region is freed) so they are ready when the region is
3650     // re-allocated. The only exception to this is if there's an
3651     // evacuation failure and instead of freeing the region we leave
3652     // it in the heap. In that case, we reset these fields during
3653     // evacuation failure handling.
3654     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3655 
3656     // Here's a good place to add any other checks we'd like to
3657     // perform on CSet regions.
3658     return false;
3659   }
3660 };
3661 #endif // ASSERT
3662 
3663 #if TASKQUEUE_STATS
3664 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3665   st->print_raw_cr("GC Task Stats");
3666   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3667   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3668 }
3669 
3670 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3671   print_taskqueue_stats_hdr(st);
3672 
3673   TaskQueueStats totals;
3674   const int n = workers() != NULL ? workers()->total_workers() : 1;
3675   for (int i = 0; i < n; ++i) {
3676     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3677     totals += task_queue(i)->stats;
3678   }
3679   st->print_raw("tot "); totals.print(st); st->cr();
3680 
3681   DEBUG_ONLY(totals.verify());
3682 }
3683 
3684 void G1CollectedHeap::reset_taskqueue_stats() {
3685   const int n = workers() != NULL ? workers()->total_workers() : 1;
3686   for (int i = 0; i < n; ++i) {
3687     task_queue(i)->stats.reset();
3688   }
3689 }
3690 #endif // TASKQUEUE_STATS
3691 
3692 void G1CollectedHeap::log_gc_header() {
3693   if (!G1Log::fine()) {
3694     return;
3695   }
3696 
3697   gclog_or_tty->date_stamp(PrintGCDateStamps);
3698   gclog_or_tty->stamp(PrintGCTimeStamps);
3699 
3700   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3701     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3702     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3703 
3704   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3705 }
3706 
3707 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3708   if (!G1Log::fine()) {
3709     return;
3710   }
3711 
3712   if (G1Log::finer()) {
3713     if (evacuation_failed()) {
3714       gclog_or_tty->print(" (to-space exhausted)");
3715     }
3716     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3717     g1_policy()->phase_times()->note_gc_end();
3718     g1_policy()->phase_times()->print(pause_time_sec);
3719     g1_policy()->print_detailed_heap_transition();
3720   } else {
3721     if (evacuation_failed()) {
3722       gclog_or_tty->print("--");
3723     }
3724     g1_policy()->print_heap_transition();
3725     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3726   }
3727   gclog_or_tty->flush();
3728 }
3729 
3730 bool
3731 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3732   assert_at_safepoint(true /* should_be_vm_thread */);
3733   guarantee(!is_gc_active(), "collection is not reentrant");
3734 
3735   if (GC_locker::check_active_before_gc()) {
3736     return false;
3737   }
3738 
3739   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3740   ResourceMark rm;
3741 
3742   print_heap_before_gc();
3743 
3744   HRSPhaseSetter x(HRSPhaseEvacuation);
3745   verify_region_sets_optional();
3746   verify_dirty_young_regions();
3747 
3748   // This call will decide whether this pause is an initial-mark
3749   // pause. If it is, during_initial_mark_pause() will return true
3750   // for the duration of this pause.
3751   g1_policy()->decide_on_conc_mark_initiation();
3752 
3753   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3754   assert(!g1_policy()->during_initial_mark_pause() ||
3755           g1_policy()->gcs_are_young(), "sanity");
3756 
3757   // We also do not allow mixed GCs during marking.
3758   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3759 
3760   // Record whether this pause is an initial mark. When the current
3761   // thread has completed its logging output and it's safe to signal
3762   // the CM thread, the flag's value in the policy has been reset.
3763   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3764 
3765   // Inner scope for scope based logging, timers, and stats collection
3766   {
3767     if (g1_policy()->during_initial_mark_pause()) {
3768       // We are about to start a marking cycle, so we increment the
3769       // full collection counter.
3770       increment_old_marking_cycles_started();
3771     }
3772     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3773 
3774     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3775                                 workers()->active_workers() : 1);
3776     double pause_start_sec = os::elapsedTime();
3777     g1_policy()->phase_times()->note_gc_start(active_workers);
3778     log_gc_header();
3779 
3780     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3781     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3782 
3783     // If the secondary_free_list is not empty, append it to the
3784     // free_list. No need to wait for the cleanup operation to finish;
3785     // the region allocation code will check the secondary_free_list
3786     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3787     // set, skip this step so that the region allocation code has to
3788     // get entries from the secondary_free_list.
3789     if (!G1StressConcRegionFreeing) {
3790       append_secondary_free_list_if_not_empty_with_lock();
3791     }
3792 
3793     assert(check_young_list_well_formed(),
3794       "young list should be well formed");
3795 
3796     // Don't dynamically change the number of GC threads this early.  A value of
3797     // 0 is used to indicate serial work.  When parallel work is done,
3798     // it will be set.
3799 
3800     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3801       IsGCActiveMark x;
3802 
3803       gc_prologue(false);
3804       increment_total_collections(false /* full gc */);
3805       increment_gc_time_stamp();
3806 
3807       verify_before_gc();
3808 
3809       COMPILER2_PRESENT(DerivedPointerTable::clear());
3810 
3811       // Please see comment in g1CollectedHeap.hpp and
3812       // G1CollectedHeap::ref_processing_init() to see how
3813       // reference processing currently works in G1.
3814 
3815       // Enable discovery in the STW reference processor
3816       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3817                                             true /*verify_no_refs*/);
3818 
3819       {
3820         // We want to temporarily turn off discovery by the
3821         // CM ref processor, if necessary, and turn it back on
3822         // on again later if we do. Using a scoped
3823         // NoRefDiscovery object will do this.
3824         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3825 
3826         // Forget the current alloc region (we might even choose it to be part
3827         // of the collection set!).
3828         release_mutator_alloc_region();
3829 
3830         // We should call this after we retire the mutator alloc
3831         // region(s) so that all the ALLOC / RETIRE events are generated
3832         // before the start GC event.
3833         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3834 
3835         // This timing is only used by the ergonomics to handle our pause target.
3836         // It is unclear why this should not include the full pause. We will
3837         // investigate this in CR 7178365.
3838         //
3839         // Preserving the old comment here if that helps the investigation:
3840         //
3841         // The elapsed time induced by the start time below deliberately elides
3842         // the possible verification above.
3843         double sample_start_time_sec = os::elapsedTime();
3844 
3845 #if YOUNG_LIST_VERBOSE
3846         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3847         _young_list->print();
3848         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3849 #endif // YOUNG_LIST_VERBOSE
3850 
3851         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3852 
3853         double scan_wait_start = os::elapsedTime();
3854         // We have to wait until the CM threads finish scanning the
3855         // root regions as it's the only way to ensure that all the
3856         // objects on them have been correctly scanned before we start
3857         // moving them during the GC.
3858         bool waited = _cm->root_regions()->wait_until_scan_finished();
3859         double wait_time_ms = 0.0;
3860         if (waited) {
3861           double scan_wait_end = os::elapsedTime();
3862           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3863         }
3864         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3865 
3866 #if YOUNG_LIST_VERBOSE
3867         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3868         _young_list->print();
3869 #endif // YOUNG_LIST_VERBOSE
3870 
3871         if (g1_policy()->during_initial_mark_pause()) {
3872           concurrent_mark()->checkpointRootsInitialPre();
3873         }
3874 
3875 #if YOUNG_LIST_VERBOSE
3876         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3877         _young_list->print();
3878         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3879 #endif // YOUNG_LIST_VERBOSE
3880 
3881         g1_policy()->finalize_cset(target_pause_time_ms);
3882 
3883         _cm->note_start_of_gc();
3884         // We should not verify the per-thread SATB buffers given that
3885         // we have not filtered them yet (we'll do so during the
3886         // GC). We also call this after finalize_cset() to
3887         // ensure that the CSet has been finalized.
3888         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3889                                  true  /* verify_enqueued_buffers */,
3890                                  false /* verify_thread_buffers */,
3891                                  true  /* verify_fingers */);
3892 
3893         if (_hr_printer.is_active()) {
3894           HeapRegion* hr = g1_policy()->collection_set();
3895           while (hr != NULL) {
3896             G1HRPrinter::RegionType type;
3897             if (!hr->is_young()) {
3898               type = G1HRPrinter::Old;
3899             } else if (hr->is_survivor()) {
3900               type = G1HRPrinter::Survivor;
3901             } else {
3902               type = G1HRPrinter::Eden;
3903             }
3904             _hr_printer.cset(hr);
3905             hr = hr->next_in_collection_set();
3906           }
3907         }
3908 
3909 #ifdef ASSERT
3910         VerifyCSetClosure cl;
3911         collection_set_iterate(&cl);
3912 #endif // ASSERT
3913 
3914         setup_surviving_young_words();
3915 
3916         // Initialize the GC alloc regions.
3917         init_gc_alloc_regions();
3918 
3919         // Actually do the work...
3920         evacuate_collection_set();
3921 
3922         // We do this to mainly verify the per-thread SATB buffers
3923         // (which have been filtered by now) since we didn't verify
3924         // them earlier. No point in re-checking the stacks / enqueued
3925         // buffers given that the CSet has not changed since last time
3926         // we checked.
3927         _cm->verify_no_cset_oops(false /* verify_stacks */,
3928                                  false /* verify_enqueued_buffers */,
3929                                  true  /* verify_thread_buffers */,
3930                                  true  /* verify_fingers */);
3931 
3932         free_collection_set(g1_policy()->collection_set());
3933         g1_policy()->clear_collection_set();
3934 
3935         cleanup_surviving_young_words();
3936 
3937         // Start a new incremental collection set for the next pause.
3938         g1_policy()->start_incremental_cset_building();
3939 
3940         // Clear the _cset_fast_test bitmap in anticipation of adding
3941         // regions to the incremental collection set for the next
3942         // evacuation pause.
3943         clear_cset_fast_test();
3944 
3945         _young_list->reset_sampled_info();
3946 
3947         // Don't check the whole heap at this point as the
3948         // GC alloc regions from this pause have been tagged
3949         // as survivors and moved on to the survivor list.
3950         // Survivor regions will fail the !is_young() check.
3951         assert(check_young_list_empty(false /* check_heap */),
3952           "young list should be empty");
3953 
3954 #if YOUNG_LIST_VERBOSE
3955         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3956         _young_list->print();
3957 #endif // YOUNG_LIST_VERBOSE
3958 
3959         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3960                                             _young_list->first_survivor_region(),
3961                                             _young_list->last_survivor_region());
3962 
3963         _young_list->reset_auxilary_lists();
3964 
3965         if (evacuation_failed()) {
3966           _summary_bytes_used = recalculate_used();
3967         } else {
3968           // The "used" of the the collection set have already been subtracted
3969           // when they were freed.  Add in the bytes evacuated.
3970           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3971         }
3972 
3973         if (g1_policy()->during_initial_mark_pause()) {
3974           // We have to do this before we notify the CM threads that
3975           // they can start working to make sure that all the
3976           // appropriate initialization is done on the CM object.
3977           concurrent_mark()->checkpointRootsInitialPost();
3978           set_marking_started();
3979           // Note that we don't actually trigger the CM thread at
3980           // this point. We do that later when we're sure that
3981           // the current thread has completed its logging output.
3982         }
3983 
3984         allocate_dummy_regions();
3985 
3986 #if YOUNG_LIST_VERBOSE
3987         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3988         _young_list->print();
3989         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3990 #endif // YOUNG_LIST_VERBOSE
3991 
3992         init_mutator_alloc_region();
3993 
3994         {
3995           size_t expand_bytes = g1_policy()->expansion_amount();
3996           if (expand_bytes > 0) {
3997             size_t bytes_before = capacity();
3998             // No need for an ergo verbose message here,
3999             // expansion_amount() does this when it returns a value > 0.
4000             if (!expand(expand_bytes)) {
4001               // We failed to expand the heap so let's verify that
4002               // committed/uncommitted amount match the backing store
4003               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4004               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4005             }
4006           }
4007         }
4008 
4009         // We redo the verificaiton but now wrt to the new CSet which
4010         // has just got initialized after the previous CSet was freed.
4011         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4012                                  true  /* verify_enqueued_buffers */,
4013                                  true  /* verify_thread_buffers */,
4014                                  true  /* verify_fingers */);
4015         _cm->note_end_of_gc();
4016 
4017         // This timing is only used by the ergonomics to handle our pause target.
4018         // It is unclear why this should not include the full pause. We will
4019         // investigate this in CR 7178365.
4020         double sample_end_time_sec = os::elapsedTime();
4021         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4022         g1_policy()->record_collection_pause_end(pause_time_ms);
4023 
4024         MemoryService::track_memory_usage();
4025 
4026         // In prepare_for_verify() below we'll need to scan the deferred
4027         // update buffers to bring the RSets up-to-date if
4028         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4029         // the update buffers we'll probably need to scan cards on the
4030         // regions we just allocated to (i.e., the GC alloc
4031         // regions). However, during the last GC we called
4032         // set_saved_mark() on all the GC alloc regions, so card
4033         // scanning might skip the [saved_mark_word()...top()] area of
4034         // those regions (i.e., the area we allocated objects into
4035         // during the last GC). But it shouldn't. Given that
4036         // saved_mark_word() is conditional on whether the GC time stamp
4037         // on the region is current or not, by incrementing the GC time
4038         // stamp here we invalidate all the GC time stamps on all the
4039         // regions and saved_mark_word() will simply return top() for
4040         // all the regions. This is a nicer way of ensuring this rather
4041         // than iterating over the regions and fixing them. In fact, the
4042         // GC time stamp increment here also ensures that
4043         // saved_mark_word() will return top() between pauses, i.e.,
4044         // during concurrent refinement. So we don't need the
4045         // is_gc_active() check to decided which top to use when
4046         // scanning cards (see CR 7039627).
4047         increment_gc_time_stamp();
4048 
4049         verify_after_gc();
4050 
4051         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4052         ref_processor_stw()->verify_no_references_recorded();
4053 
4054         // CM reference discovery will be re-enabled if necessary.
4055       }
4056 
4057       // We should do this after we potentially expand the heap so
4058       // that all the COMMIT events are generated before the end GC
4059       // event, and after we retire the GC alloc regions so that all
4060       // RETIRE events are generated before the end GC event.
4061       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4062 
4063       if (mark_in_progress()) {
4064         concurrent_mark()->update_g1_committed();
4065       }
4066 
4067 #ifdef TRACESPINNING
4068       ParallelTaskTerminator::print_termination_counts();
4069 #endif
4070 
4071       gc_epilogue(false);
4072     }
4073 
4074     // Print the remainder of the GC log output.
4075     log_gc_footer(os::elapsedTime() - pause_start_sec);
4076 
4077     // It is not yet to safe to tell the concurrent mark to
4078     // start as we have some optional output below. We don't want the
4079     // output from the concurrent mark thread interfering with this
4080     // logging output either.
4081 
4082     _hrs.verify_optional();
4083     verify_region_sets_optional();
4084 
4085     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4086     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4087 
4088     print_heap_after_gc();
4089 
4090     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4091     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4092     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4093     // before any GC notifications are raised.
4094     g1mm()->update_sizes();
4095   }
4096 
4097   if (G1SummarizeRSetStats &&
4098       (G1SummarizeRSetStatsPeriod > 0) &&
4099       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
4100     g1_rem_set()->print_summary_info();
4101   }
4102 
4103   // It should now be safe to tell the concurrent mark thread to start
4104   // without its logging output interfering with the logging output
4105   // that came from the pause.
4106 
4107   if (should_start_conc_mark) {
4108     // CAUTION: after the doConcurrentMark() call below,
4109     // the concurrent marking thread(s) could be running
4110     // concurrently with us. Make sure that anything after
4111     // this point does not assume that we are the only GC thread
4112     // running. Note: of course, the actual marking work will
4113     // not start until the safepoint itself is released in
4114     // ConcurrentGCThread::safepoint_desynchronize().
4115     doConcurrentMark();
4116   }
4117 
4118   return true;
4119 }
4120 
4121 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4122 {
4123   size_t gclab_word_size;
4124   switch (purpose) {
4125     case GCAllocForSurvived:
4126       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4127       break;
4128     case GCAllocForTenured:
4129       gclab_word_size = _old_plab_stats.desired_plab_sz();
4130       break;
4131     default:
4132       assert(false, "unknown GCAllocPurpose");
4133       gclab_word_size = _old_plab_stats.desired_plab_sz();
4134       break;
4135   }
4136 
4137   // Prevent humongous PLAB sizes for two reasons:
4138   // * PLABs are allocated using a similar paths as oops, but should
4139   //   never be in a humongous region
4140   // * Allowing humongous PLABs needlessly churns the region free lists
4141   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4142 }
4143 
4144 void G1CollectedHeap::init_mutator_alloc_region() {
4145   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4146   _mutator_alloc_region.init();
4147 }
4148 
4149 void G1CollectedHeap::release_mutator_alloc_region() {
4150   _mutator_alloc_region.release();
4151   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4152 }
4153 
4154 void G1CollectedHeap::init_gc_alloc_regions() {
4155   assert_at_safepoint(true /* should_be_vm_thread */);
4156 
4157   _survivor_gc_alloc_region.init();
4158   _old_gc_alloc_region.init();
4159   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4160   _retained_old_gc_alloc_region = NULL;
4161 
4162   // We will discard the current GC alloc region if:
4163   // a) it's in the collection set (it can happen!),
4164   // b) it's already full (no point in using it),
4165   // c) it's empty (this means that it was emptied during
4166   // a cleanup and it should be on the free list now), or
4167   // d) it's humongous (this means that it was emptied
4168   // during a cleanup and was added to the free list, but
4169   // has been subseqently used to allocate a humongous
4170   // object that may be less than the region size).
4171   if (retained_region != NULL &&
4172       !retained_region->in_collection_set() &&
4173       !(retained_region->top() == retained_region->end()) &&
4174       !retained_region->is_empty() &&
4175       !retained_region->isHumongous()) {
4176     retained_region->set_saved_mark();
4177     // The retained region was added to the old region set when it was
4178     // retired. We have to remove it now, since we don't allow regions
4179     // we allocate to in the region sets. We'll re-add it later, when
4180     // it's retired again.
4181     _old_set.remove(retained_region);
4182     bool during_im = g1_policy()->during_initial_mark_pause();
4183     retained_region->note_start_of_copying(during_im);
4184     _old_gc_alloc_region.set(retained_region);
4185     _hr_printer.reuse(retained_region);
4186   }
4187 }
4188 
4189 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers) {
4190   _survivor_gc_alloc_region.release();
4191   // If we have an old GC alloc region to release, we'll save it in
4192   // _retained_old_gc_alloc_region. If we don't
4193   // _retained_old_gc_alloc_region will become NULL. This is what we
4194   // want either way so no reason to check explicitly for either
4195   // condition.
4196   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4197 
4198   if (ResizePLAB) {
4199     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4200     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4201   }
4202 }
4203 
4204 void G1CollectedHeap::abandon_gc_alloc_regions() {
4205   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4206   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4207   _retained_old_gc_alloc_region = NULL;
4208 }
4209 
4210 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4211   _drain_in_progress = false;
4212   set_evac_failure_closure(cl);
4213   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4214 }
4215 
4216 void G1CollectedHeap::finalize_for_evac_failure() {
4217   assert(_evac_failure_scan_stack != NULL &&
4218          _evac_failure_scan_stack->length() == 0,
4219          "Postcondition");
4220   assert(!_drain_in_progress, "Postcondition");
4221   delete _evac_failure_scan_stack;
4222   _evac_failure_scan_stack = NULL;
4223 }
4224 
4225 void G1CollectedHeap::remove_self_forwarding_pointers() {
4226   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4227 
4228   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4229 
4230   if (G1CollectedHeap::use_parallel_gc_threads()) {
4231     set_par_threads();
4232     workers()->run_task(&rsfp_task);
4233     set_par_threads(0);
4234   } else {
4235     rsfp_task.work(0);
4236   }
4237 
4238   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4239 
4240   // Reset the claim values in the regions in the collection set.
4241   reset_cset_heap_region_claim_values();
4242 
4243   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4244 
4245   // Now restore saved marks, if any.
4246   assert(_objs_with_preserved_marks.size() ==
4247             _preserved_marks_of_objs.size(), "Both or none.");
4248   while (!_objs_with_preserved_marks.is_empty()) {
4249     oop obj = _objs_with_preserved_marks.pop();
4250     markOop m = _preserved_marks_of_objs.pop();
4251     obj->set_mark(m);
4252   }
4253   _objs_with_preserved_marks.clear(true);
4254   _preserved_marks_of_objs.clear(true);
4255 }
4256 
4257 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4258   _evac_failure_scan_stack->push(obj);
4259 }
4260 
4261 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4262   assert(_evac_failure_scan_stack != NULL, "precondition");
4263 
4264   while (_evac_failure_scan_stack->length() > 0) {
4265      oop obj = _evac_failure_scan_stack->pop();
4266      _evac_failure_closure->set_region(heap_region_containing(obj));
4267      obj->oop_iterate_backwards(_evac_failure_closure);
4268   }
4269 }
4270 
4271 oop
4272 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4273                                                oop old) {
4274   assert(obj_in_cs(old),
4275          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4276                  (HeapWord*) old));
4277   markOop m = old->mark();
4278   oop forward_ptr = old->forward_to_atomic(old);
4279   if (forward_ptr == NULL) {
4280     // Forward-to-self succeeded.
4281 
4282     if (_evac_failure_closure != cl) {
4283       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4284       assert(!_drain_in_progress,
4285              "Should only be true while someone holds the lock.");
4286       // Set the global evac-failure closure to the current thread's.
4287       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4288       set_evac_failure_closure(cl);
4289       // Now do the common part.
4290       handle_evacuation_failure_common(old, m);
4291       // Reset to NULL.
4292       set_evac_failure_closure(NULL);
4293     } else {
4294       // The lock is already held, and this is recursive.
4295       assert(_drain_in_progress, "This should only be the recursive case.");
4296       handle_evacuation_failure_common(old, m);
4297     }
4298     return old;
4299   } else {
4300     // Forward-to-self failed. Either someone else managed to allocate
4301     // space for this object (old != forward_ptr) or they beat us in
4302     // self-forwarding it (old == forward_ptr).
4303     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4304            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4305                    "should not be in the CSet",
4306                    (HeapWord*) old, (HeapWord*) forward_ptr));
4307     return forward_ptr;
4308   }
4309 }
4310 
4311 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4312   set_evacuation_failed(true);
4313 
4314   preserve_mark_if_necessary(old, m);
4315 
4316   HeapRegion* r = heap_region_containing(old);
4317   if (!r->evacuation_failed()) {
4318     r->set_evacuation_failed(true);
4319     _hr_printer.evac_failure(r);
4320   }
4321 
4322   push_on_evac_failure_scan_stack(old);
4323 
4324   if (!_drain_in_progress) {
4325     // prevent recursion in copy_to_survivor_space()
4326     _drain_in_progress = true;
4327     drain_evac_failure_scan_stack();
4328     _drain_in_progress = false;
4329   }
4330 }
4331 
4332 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4333   assert(evacuation_failed(), "Oversaving!");
4334   // We want to call the "for_promotion_failure" version only in the
4335   // case of a promotion failure.
4336   if (m->must_be_preserved_for_promotion_failure(obj)) {
4337     _objs_with_preserved_marks.push(obj);
4338     _preserved_marks_of_objs.push(m);
4339   }
4340 }
4341 
4342 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4343                                                   size_t word_size) {
4344   if (purpose == GCAllocForSurvived) {
4345     HeapWord* result = survivor_attempt_allocation(word_size);
4346     if (result != NULL) {
4347       return result;
4348     } else {
4349       // Let's try to allocate in the old gen in case we can fit the
4350       // object there.
4351       return old_attempt_allocation(word_size);
4352     }
4353   } else {
4354     assert(purpose ==  GCAllocForTenured, "sanity");
4355     HeapWord* result = old_attempt_allocation(word_size);
4356     if (result != NULL) {
4357       return result;
4358     } else {
4359       // Let's try to allocate in the survivors in case we can fit the
4360       // object there.
4361       return survivor_attempt_allocation(word_size);
4362     }
4363   }
4364 
4365   ShouldNotReachHere();
4366   // Trying to keep some compilers happy.
4367   return NULL;
4368 }
4369 
4370 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4371   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4372 
4373 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4374   : _g1h(g1h),
4375     _refs(g1h->task_queue(queue_num)),
4376     _dcq(&g1h->dirty_card_queue_set()),
4377     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4378     _g1_rem(g1h->g1_rem_set()),
4379     _hash_seed(17), _queue_num(queue_num),
4380     _term_attempts(0),
4381     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4382     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4383     _age_table(false),
4384     _strong_roots_time(0), _term_time(0),
4385     _alloc_buffer_waste(0), _undo_waste(0) {
4386   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4387   // we "sacrifice" entry 0 to keep track of surviving bytes for
4388   // non-young regions (where the age is -1)
4389   // We also add a few elements at the beginning and at the end in
4390   // an attempt to eliminate cache contention
4391   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4392   uint array_length = PADDING_ELEM_NUM +
4393                       real_length +
4394                       PADDING_ELEM_NUM;
4395   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4396   if (_surviving_young_words_base == NULL)
4397     vm_exit_out_of_memory(array_length * sizeof(size_t),
4398                           "Not enough space for young surv histo.");
4399   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4400   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4401 
4402   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4403   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4404 
4405   _start = os::elapsedTime();
4406 }
4407 
4408 void
4409 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4410 {
4411   st->print_raw_cr("GC Termination Stats");
4412   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4413                    " ------waste (KiB)------");
4414   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4415                    "  total   alloc    undo");
4416   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4417                    " ------- ------- -------");
4418 }
4419 
4420 void
4421 G1ParScanThreadState::print_termination_stats(int i,
4422                                               outputStream* const st) const
4423 {
4424   const double elapsed_ms = elapsed_time() * 1000.0;
4425   const double s_roots_ms = strong_roots_time() * 1000.0;
4426   const double term_ms    = term_time() * 1000.0;
4427   st->print_cr("%3d %9.2f %9.2f %6.2f "
4428                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4429                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4430                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4431                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4432                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4433                alloc_buffer_waste() * HeapWordSize / K,
4434                undo_waste() * HeapWordSize / K);
4435 }
4436 
4437 #ifdef ASSERT
4438 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4439   assert(ref != NULL, "invariant");
4440   assert(UseCompressedOops, "sanity");
4441   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4442   oop p = oopDesc::load_decode_heap_oop(ref);
4443   assert(_g1h->is_in_g1_reserved(p),
4444          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4445   return true;
4446 }
4447 
4448 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4449   assert(ref != NULL, "invariant");
4450   if (has_partial_array_mask(ref)) {
4451     // Must be in the collection set--it's already been copied.
4452     oop p = clear_partial_array_mask(ref);
4453     assert(_g1h->obj_in_cs(p),
4454            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4455   } else {
4456     oop p = oopDesc::load_decode_heap_oop(ref);
4457     assert(_g1h->is_in_g1_reserved(p),
4458            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4459   }
4460   return true;
4461 }
4462 
4463 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4464   if (ref.is_narrow()) {
4465     return verify_ref((narrowOop*) ref);
4466   } else {
4467     return verify_ref((oop*) ref);
4468   }
4469 }
4470 #endif // ASSERT
4471 
4472 void G1ParScanThreadState::trim_queue() {
4473   assert(_evac_cl != NULL, "not set");
4474   assert(_evac_failure_cl != NULL, "not set");
4475   assert(_partial_scan_cl != NULL, "not set");
4476 
4477   StarTask ref;
4478   do {
4479     // Drain the overflow stack first, so other threads can steal.
4480     while (refs()->pop_overflow(ref)) {
4481       deal_with_reference(ref);
4482     }
4483 
4484     while (refs()->pop_local(ref)) {
4485       deal_with_reference(ref);
4486     }
4487   } while (!refs()->is_empty());
4488 }
4489 
4490 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4491                                      G1ParScanThreadState* par_scan_state) :
4492   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4493   _par_scan_state(par_scan_state),
4494   _worker_id(par_scan_state->queue_num()),
4495   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4496   _mark_in_progress(_g1->mark_in_progress()) { }
4497 
4498 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4499 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4500 #ifdef ASSERT
4501   HeapRegion* hr = _g1->heap_region_containing(obj);
4502   assert(hr != NULL, "sanity");
4503   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4504 #endif // ASSERT
4505 
4506   // We know that the object is not moving so it's safe to read its size.
4507   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4508 }
4509 
4510 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4511 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4512   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4513 #ifdef ASSERT
4514   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4515   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4516   assert(from_obj != to_obj, "should not be self-forwarded");
4517 
4518   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4519   assert(from_hr != NULL, "sanity");
4520   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4521 
4522   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4523   assert(to_hr != NULL, "sanity");
4524   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4525 #endif // ASSERT
4526 
4527   // The object might be in the process of being copied by another
4528   // worker so we cannot trust that its to-space image is
4529   // well-formed. So we have to read its size from its from-space
4530   // image which we know should not be changing.
4531   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4532 }
4533 
4534 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4535 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4536   ::copy_to_survivor_space(oop old) {
4537   size_t word_sz = old->size();
4538   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4539   // +1 to make the -1 indexes valid...
4540   int       young_index = from_region->young_index_in_cset()+1;
4541   assert( (from_region->is_young() && young_index >  0) ||
4542          (!from_region->is_young() && young_index == 0), "invariant" );
4543   G1CollectorPolicy* g1p = _g1->g1_policy();
4544   markOop m = old->mark();
4545   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4546                                            : m->age();
4547   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4548                                                              word_sz);
4549   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4550 #ifndef PRODUCT
4551   // Should this evacuation fail?
4552   if (_g1->evacuation_should_fail()) {
4553     if (obj_ptr != NULL) {
4554       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4555       obj_ptr = NULL;
4556     }
4557   }
4558 #endif // !PRODUCT
4559 
4560   if (obj_ptr == NULL) {
4561     // This will either forward-to-self, or detect that someone else has
4562     // installed a forwarding pointer.
4563     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4564     return _g1->handle_evacuation_failure_par(cl, old);
4565   }
4566 
4567   oop obj = oop(obj_ptr);
4568 
4569   // We're going to allocate linearly, so might as well prefetch ahead.
4570   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4571 
4572   oop forward_ptr = old->forward_to_atomic(obj);
4573   if (forward_ptr == NULL) {
4574     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4575     if (g1p->track_object_age(alloc_purpose)) {
4576       // We could simply do obj->incr_age(). However, this causes a
4577       // performance issue. obj->incr_age() will first check whether
4578       // the object has a displaced mark by checking its mark word;
4579       // getting the mark word from the new location of the object
4580       // stalls. So, given that we already have the mark word and we
4581       // are about to install it anyway, it's better to increase the
4582       // age on the mark word, when the object does not have a
4583       // displaced mark word. We're not expecting many objects to have
4584       // a displaced marked word, so that case is not optimized
4585       // further (it could be...) and we simply call obj->incr_age().
4586 
4587       if (m->has_displaced_mark_helper()) {
4588         // in this case, we have to install the mark word first,
4589         // otherwise obj looks to be forwarded (the old mark word,
4590         // which contains the forward pointer, was copied)
4591         obj->set_mark(m);
4592         obj->incr_age();
4593       } else {
4594         m = m->incr_age();
4595         obj->set_mark(m);
4596       }
4597       _par_scan_state->age_table()->add(obj, word_sz);
4598     } else {
4599       obj->set_mark(m);
4600     }
4601 
4602     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4603     surv_young_words[young_index] += word_sz;
4604 
4605     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4606       // We keep track of the next start index in the length field of
4607       // the to-space object. The actual length can be found in the
4608       // length field of the from-space object.
4609       arrayOop(obj)->set_length(0);
4610       oop* old_p = set_partial_array_mask(old);
4611       _par_scan_state->push_on_queue(old_p);
4612     } else {
4613       // No point in using the slower heap_region_containing() method,
4614       // given that we know obj is in the heap.
4615       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4616       obj->oop_iterate_backwards(&_scanner);
4617     }
4618   } else {
4619     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4620     obj = forward_ptr;
4621   }
4622   return obj;
4623 }
4624 
4625 template <class T>
4626 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4627   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4628     _scanned_klass->record_modified_oops();
4629   }
4630 }
4631 
4632 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4633 template <class T>
4634 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4635 ::do_oop_work(T* p) {
4636   oop obj = oopDesc::load_decode_heap_oop(p);
4637   assert(barrier != G1BarrierRS || obj != NULL,
4638          "Precondition: G1BarrierRS implies obj is non-NULL");
4639 
4640   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4641 
4642   // here the null check is implicit in the cset_fast_test() test
4643   if (_g1->in_cset_fast_test(obj)) {
4644     oop forwardee;
4645     if (obj->is_forwarded()) {
4646       forwardee = obj->forwardee();
4647     } else {
4648       forwardee = copy_to_survivor_space(obj);
4649     }
4650     assert(forwardee != NULL, "forwardee should not be NULL");
4651     oopDesc::encode_store_heap_oop(p, forwardee);
4652     if (do_mark_object && forwardee != obj) {
4653       // If the object is self-forwarded we don't need to explicitly
4654       // mark it, the evacuation failure protocol will do so.
4655       mark_forwarded_object(obj, forwardee);
4656     }
4657 
4658     // When scanning the RS, we only care about objs in CS.
4659     if (barrier == G1BarrierRS) {
4660       _par_scan_state->update_rs(_from, p, _worker_id);
4661     } else if (barrier == G1BarrierKlass) {
4662       do_klass_barrier(p, forwardee);
4663     }
4664   } else {
4665     // The object is not in collection set. If we're a root scanning
4666     // closure during an initial mark pause (i.e. do_mark_object will
4667     // be true) then attempt to mark the object.
4668     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4669       mark_object(obj);
4670     }
4671   }
4672 
4673   if (barrier == G1BarrierEvac && obj != NULL) {
4674     _par_scan_state->update_rs(_from, p, _worker_id);
4675   }
4676 
4677   if (do_gen_barrier && obj != NULL) {
4678     par_do_barrier(p);
4679   }
4680 }
4681 
4682 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4683 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4684 
4685 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4686   assert(has_partial_array_mask(p), "invariant");
4687   oop from_obj = clear_partial_array_mask(p);
4688 
4689   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4690   assert(from_obj->is_objArray(), "must be obj array");
4691   objArrayOop from_obj_array = objArrayOop(from_obj);
4692   // The from-space object contains the real length.
4693   int length                 = from_obj_array->length();
4694 
4695   assert(from_obj->is_forwarded(), "must be forwarded");
4696   oop to_obj                 = from_obj->forwardee();
4697   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4698   objArrayOop to_obj_array   = objArrayOop(to_obj);
4699   // We keep track of the next start index in the length field of the
4700   // to-space object.
4701   int next_index             = to_obj_array->length();
4702   assert(0 <= next_index && next_index < length,
4703          err_msg("invariant, next index: %d, length: %d", next_index, length));
4704 
4705   int start                  = next_index;
4706   int end                    = length;
4707   int remainder              = end - start;
4708   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4709   if (remainder > 2 * ParGCArrayScanChunk) {
4710     end = start + ParGCArrayScanChunk;
4711     to_obj_array->set_length(end);
4712     // Push the remainder before we process the range in case another
4713     // worker has run out of things to do and can steal it.
4714     oop* from_obj_p = set_partial_array_mask(from_obj);
4715     _par_scan_state->push_on_queue(from_obj_p);
4716   } else {
4717     assert(length == end, "sanity");
4718     // We'll process the final range for this object. Restore the length
4719     // so that the heap remains parsable in case of evacuation failure.
4720     to_obj_array->set_length(end);
4721   }
4722   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4723   // Process indexes [start,end). It will also process the header
4724   // along with the first chunk (i.e., the chunk with start == 0).
4725   // Note that at this point the length field of to_obj_array is not
4726   // correct given that we are using it to keep track of the next
4727   // start index. oop_iterate_range() (thankfully!) ignores the length
4728   // field and only relies on the start / end parameters.  It does
4729   // however return the size of the object which will be incorrect. So
4730   // we have to ignore it even if we wanted to use it.
4731   to_obj_array->oop_iterate_range(&_scanner, start, end);
4732 }
4733 
4734 class G1ParEvacuateFollowersClosure : public VoidClosure {
4735 protected:
4736   G1CollectedHeap*              _g1h;
4737   G1ParScanThreadState*         _par_scan_state;
4738   RefToScanQueueSet*            _queues;
4739   ParallelTaskTerminator*       _terminator;
4740 
4741   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4742   RefToScanQueueSet*      queues()         { return _queues; }
4743   ParallelTaskTerminator* terminator()     { return _terminator; }
4744 
4745 public:
4746   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4747                                 G1ParScanThreadState* par_scan_state,
4748                                 RefToScanQueueSet* queues,
4749                                 ParallelTaskTerminator* terminator)
4750     : _g1h(g1h), _par_scan_state(par_scan_state),
4751       _queues(queues), _terminator(terminator) {}
4752 
4753   void do_void();
4754 
4755 private:
4756   inline bool offer_termination();
4757 };
4758 
4759 bool G1ParEvacuateFollowersClosure::offer_termination() {
4760   G1ParScanThreadState* const pss = par_scan_state();
4761   pss->start_term_time();
4762   const bool res = terminator()->offer_termination();
4763   pss->end_term_time();
4764   return res;
4765 }
4766 
4767 void G1ParEvacuateFollowersClosure::do_void() {
4768   StarTask stolen_task;
4769   G1ParScanThreadState* const pss = par_scan_state();
4770   pss->trim_queue();
4771 
4772   do {
4773     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4774       assert(pss->verify_task(stolen_task), "sanity");
4775       if (stolen_task.is_narrow()) {
4776         pss->deal_with_reference((narrowOop*) stolen_task);
4777       } else {
4778         pss->deal_with_reference((oop*) stolen_task);
4779       }
4780 
4781       // We've just processed a reference and we might have made
4782       // available new entries on the queues. So we have to make sure
4783       // we drain the queues as necessary.
4784       pss->trim_queue();
4785     }
4786   } while (!offer_termination());
4787 
4788   pss->retire_alloc_buffers();
4789 }
4790 
4791 class G1KlassScanClosure : public KlassClosure {
4792  G1ParCopyHelper* _closure;
4793  bool             _process_only_dirty;
4794  int              _count;
4795  public:
4796   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4797       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4798   void do_klass(Klass* klass) {
4799     // If the klass has not been dirtied we know that there's
4800     // no references into  the young gen and we can skip it.
4801    if (!_process_only_dirty || klass->has_modified_oops()) {
4802       // Clean the klass since we're going to scavenge all the metadata.
4803       klass->clear_modified_oops();
4804 
4805       // Tell the closure that this klass is the Klass to scavenge
4806       // and is the one to dirty if oops are left pointing into the young gen.
4807       _closure->set_scanned_klass(klass);
4808 
4809       klass->oops_do(_closure);
4810 
4811       _closure->set_scanned_klass(NULL);
4812     }
4813     _count++;
4814   }
4815 };
4816 
4817 class G1ParTask : public AbstractGangTask {
4818 protected:
4819   G1CollectedHeap*       _g1h;
4820   RefToScanQueueSet      *_queues;
4821   ParallelTaskTerminator _terminator;
4822   uint _n_workers;
4823 
4824   Mutex _stats_lock;
4825   Mutex* stats_lock() { return &_stats_lock; }
4826 
4827   size_t getNCards() {
4828     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4829       / G1BlockOffsetSharedArray::N_bytes;
4830   }
4831 
4832 public:
4833   G1ParTask(G1CollectedHeap* g1h,
4834             RefToScanQueueSet *task_queues)
4835     : AbstractGangTask("G1 collection"),
4836       _g1h(g1h),
4837       _queues(task_queues),
4838       _terminator(0, _queues),
4839       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4840   {}
4841 
4842   RefToScanQueueSet* queues() { return _queues; }
4843 
4844   RefToScanQueue *work_queue(int i) {
4845     return queues()->queue(i);
4846   }
4847 
4848   ParallelTaskTerminator* terminator() { return &_terminator; }
4849 
4850   virtual void set_for_termination(int active_workers) {
4851     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4852     // in the young space (_par_seq_tasks) in the G1 heap
4853     // for SequentialSubTasksDone.
4854     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4855     // both of which need setting by set_n_termination().
4856     _g1h->SharedHeap::set_n_termination(active_workers);
4857     _g1h->set_n_termination(active_workers);
4858     terminator()->reset_for_reuse(active_workers);
4859     _n_workers = active_workers;
4860   }
4861 
4862   void work(uint worker_id) {
4863     if (worker_id >= _n_workers) return;  // no work needed this round
4864 
4865     double start_time_ms = os::elapsedTime() * 1000.0;
4866     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4867 
4868     {
4869       ResourceMark rm;
4870       HandleMark   hm;
4871 
4872       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4873 
4874       G1ParScanThreadState            pss(_g1h, worker_id);
4875       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
4876       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4877       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
4878 
4879       pss.set_evac_closure(&scan_evac_cl);
4880       pss.set_evac_failure_closure(&evac_failure_cl);
4881       pss.set_partial_scan_closure(&partial_scan_cl);
4882 
4883       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4884       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
4885 
4886       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4887       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4888 
4889       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
4890       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4891       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4892 
4893       OopClosure*                    scan_root_cl = &only_scan_root_cl;
4894       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
4895 
4896       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4897         // We also need to mark copied objects.
4898         scan_root_cl = &scan_mark_root_cl;
4899         scan_klasses_cl = &scan_mark_klasses_cl_s;
4900       }
4901 
4902       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
4903 
4904       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
4905 
4906       pss.start_strong_roots();
4907       _g1h->g1_process_strong_roots(/* is scavenging */ true,
4908                                     SharedHeap::ScanningOption(so),
4909                                     scan_root_cl,
4910                                     &push_heap_rs_cl,
4911                                     scan_klasses_cl,
4912                                     worker_id);
4913       pss.end_strong_roots();
4914 
4915       {
4916         double start = os::elapsedTime();
4917         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4918         evac.do_void();
4919         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4920         double term_ms = pss.term_time()*1000.0;
4921         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4922         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4923       }
4924       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4925       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4926 
4927       if (ParallelGCVerbose) {
4928         MutexLocker x(stats_lock());
4929         pss.print_termination_stats(worker_id);
4930       }
4931 
4932       assert(pss.refs()->is_empty(), "should be empty");
4933 
4934       // Close the inner scope so that the ResourceMark and HandleMark
4935       // destructors are executed here and are included as part of the
4936       // "GC Worker Time".
4937     }
4938 
4939     double end_time_ms = os::elapsedTime() * 1000.0;
4940     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4941   }
4942 };
4943 
4944 // *** Common G1 Evacuation Stuff
4945 
4946 // Closures that support the filtering of CodeBlobs scanned during
4947 // external root scanning.
4948 
4949 // Closure applied to reference fields in code blobs (specifically nmethods)
4950 // to determine whether an nmethod contains references that point into
4951 // the collection set. Used as a predicate when walking code roots so
4952 // that only nmethods that point into the collection set are added to the
4953 // 'marked' list.
4954 
4955 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
4956 
4957   class G1PointsIntoCSOopClosure : public OopClosure {
4958     G1CollectedHeap* _g1;
4959     bool _points_into_cs;
4960   public:
4961     G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
4962       _g1(g1), _points_into_cs(false) { }
4963 
4964     bool points_into_cs() const { return _points_into_cs; }
4965 
4966     template <class T>
4967     void do_oop_nv(T* p) {
4968       if (!_points_into_cs) {
4969         T heap_oop = oopDesc::load_heap_oop(p);
4970         if (!oopDesc::is_null(heap_oop) &&
4971             _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
4972           _points_into_cs = true;
4973         }
4974       }
4975     }
4976 
4977     virtual void do_oop(oop* p)        { do_oop_nv(p); }
4978     virtual void do_oop(narrowOop* p)  { do_oop_nv(p); }
4979   };
4980 
4981   G1CollectedHeap* _g1;
4982 
4983 public:
4984   G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
4985     CodeBlobToOopClosure(cl, true), _g1(g1) { }
4986 
4987   virtual void do_code_blob(CodeBlob* cb) {
4988     nmethod* nm = cb->as_nmethod_or_null();
4989     if (nm != NULL && !(nm->test_oops_do_mark())) {
4990       G1PointsIntoCSOopClosure predicate_cl(_g1);
4991       nm->oops_do(&predicate_cl);
4992 
4993       if (predicate_cl.points_into_cs()) {
4994         // At least one of the reference fields or the oop relocations
4995         // in the nmethod points into the collection set. We have to
4996         // 'mark' this nmethod.
4997         // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
4998         // or MarkingCodeBlobClosure::do_code_blob() change.
4999         if (!nm->test_set_oops_do_mark()) {
5000           do_newly_marked_nmethod(nm);
5001         }
5002       }
5003     }
5004   }
5005 };
5006 
5007 // This method is run in a GC worker.
5008 
5009 void
5010 G1CollectedHeap::
5011 g1_process_strong_roots(bool is_scavenging,
5012                         ScanningOption so,
5013                         OopClosure* scan_non_heap_roots,
5014                         OopsInHeapRegionClosure* scan_rs,
5015                         G1KlassScanClosure* scan_klasses,
5016                         int worker_i) {
5017 
5018   // First scan the strong roots
5019   double ext_roots_start = os::elapsedTime();
5020   double closure_app_time_sec = 0.0;
5021 
5022   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5023 
5024   // Walk the code cache w/o buffering, because StarTask cannot handle
5025   // unaligned oop locations.
5026   G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5027 
5028   process_strong_roots(false, // no scoping; this is parallel code
5029                        is_scavenging, so,
5030                        &buf_scan_non_heap_roots,
5031                        &eager_scan_code_roots,
5032                        scan_klasses
5033                        );
5034 
5035   // Now the CM ref_processor roots.
5036   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5037     // We need to treat the discovered reference lists of the
5038     // concurrent mark ref processor as roots and keep entries
5039     // (which are added by the marking threads) on them live
5040     // until they can be processed at the end of marking.
5041     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5042   }
5043 
5044   // Finish up any enqueued closure apps (attributed as object copy time).
5045   buf_scan_non_heap_roots.done();
5046 
5047   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5048 
5049   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5050 
5051   double ext_root_time_ms =
5052     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5053 
5054   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5055 
5056   // During conc marking we have to filter the per-thread SATB buffers
5057   // to make sure we remove any oops into the CSet (which will show up
5058   // as implicitly live).
5059   double satb_filtering_ms = 0.0;
5060   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5061     if (mark_in_progress()) {
5062       double satb_filter_start = os::elapsedTime();
5063 
5064       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5065 
5066       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5067     }
5068   }
5069   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5070 
5071   // Now scan the complement of the collection set.
5072   if (scan_rs != NULL) {
5073     g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5074   }
5075   _process_strong_tasks->all_tasks_completed();
5076 }
5077 
5078 void
5079 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5080   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5081   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5082 }
5083 
5084 // Weak Reference Processing support
5085 
5086 // An always "is_alive" closure that is used to preserve referents.
5087 // If the object is non-null then it's alive.  Used in the preservation
5088 // of referent objects that are pointed to by reference objects
5089 // discovered by the CM ref processor.
5090 class G1AlwaysAliveClosure: public BoolObjectClosure {
5091   G1CollectedHeap* _g1;
5092 public:
5093   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5094   void do_object(oop p) { assert(false, "Do not call."); }
5095   bool do_object_b(oop p) {
5096     if (p != NULL) {
5097       return true;
5098     }
5099     return false;
5100   }
5101 };
5102 
5103 bool G1STWIsAliveClosure::do_object_b(oop p) {
5104   // An object is reachable if it is outside the collection set,
5105   // or is inside and copied.
5106   return !_g1->obj_in_cs(p) || p->is_forwarded();
5107 }
5108 
5109 // Non Copying Keep Alive closure
5110 class G1KeepAliveClosure: public OopClosure {
5111   G1CollectedHeap* _g1;
5112 public:
5113   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5114   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5115   void do_oop(      oop* p) {
5116     oop obj = *p;
5117 
5118     if (_g1->obj_in_cs(obj)) {
5119       assert( obj->is_forwarded(), "invariant" );
5120       *p = obj->forwardee();
5121     }
5122   }
5123 };
5124 
5125 // Copying Keep Alive closure - can be called from both
5126 // serial and parallel code as long as different worker
5127 // threads utilize different G1ParScanThreadState instances
5128 // and different queues.
5129 
5130 class G1CopyingKeepAliveClosure: public OopClosure {
5131   G1CollectedHeap*         _g1h;
5132   OopClosure*              _copy_non_heap_obj_cl;
5133   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5134   G1ParScanThreadState*    _par_scan_state;
5135 
5136 public:
5137   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5138                             OopClosure* non_heap_obj_cl,
5139                             OopsInHeapRegionClosure* metadata_obj_cl,
5140                             G1ParScanThreadState* pss):
5141     _g1h(g1h),
5142     _copy_non_heap_obj_cl(non_heap_obj_cl),
5143     _copy_metadata_obj_cl(metadata_obj_cl),
5144     _par_scan_state(pss)
5145   {}
5146 
5147   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5148   virtual void do_oop(      oop* p) { do_oop_work(p); }
5149 
5150   template <class T> void do_oop_work(T* p) {
5151     oop obj = oopDesc::load_decode_heap_oop(p);
5152 
5153     if (_g1h->obj_in_cs(obj)) {
5154       // If the referent object has been forwarded (either copied
5155       // to a new location or to itself in the event of an
5156       // evacuation failure) then we need to update the reference
5157       // field and, if both reference and referent are in the G1
5158       // heap, update the RSet for the referent.
5159       //
5160       // If the referent has not been forwarded then we have to keep
5161       // it alive by policy. Therefore we have copy the referent.
5162       //
5163       // If the reference field is in the G1 heap then we can push
5164       // on the PSS queue. When the queue is drained (after each
5165       // phase of reference processing) the object and it's followers
5166       // will be copied, the reference field set to point to the
5167       // new location, and the RSet updated. Otherwise we need to
5168       // use the the non-heap or metadata closures directly to copy
5169       // the refernt object and update the pointer, while avoiding
5170       // updating the RSet.
5171 
5172       if (_g1h->is_in_g1_reserved(p)) {
5173         _par_scan_state->push_on_queue(p);
5174       } else {
5175         assert(!ClassLoaderDataGraph::contains((address)p),
5176                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5177                               PTR_FORMAT, p));
5178           _copy_non_heap_obj_cl->do_oop(p);
5179         }
5180       }
5181     }
5182 };
5183 
5184 // Serial drain queue closure. Called as the 'complete_gc'
5185 // closure for each discovered list in some of the
5186 // reference processing phases.
5187 
5188 class G1STWDrainQueueClosure: public VoidClosure {
5189 protected:
5190   G1CollectedHeap* _g1h;
5191   G1ParScanThreadState* _par_scan_state;
5192 
5193   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5194 
5195 public:
5196   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5197     _g1h(g1h),
5198     _par_scan_state(pss)
5199   { }
5200 
5201   void do_void() {
5202     G1ParScanThreadState* const pss = par_scan_state();
5203     pss->trim_queue();
5204   }
5205 };
5206 
5207 // Parallel Reference Processing closures
5208 
5209 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5210 // processing during G1 evacuation pauses.
5211 
5212 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5213 private:
5214   G1CollectedHeap*   _g1h;
5215   RefToScanQueueSet* _queues;
5216   FlexibleWorkGang*  _workers;
5217   int                _active_workers;
5218 
5219 public:
5220   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5221                         FlexibleWorkGang* workers,
5222                         RefToScanQueueSet *task_queues,
5223                         int n_workers) :
5224     _g1h(g1h),
5225     _queues(task_queues),
5226     _workers(workers),
5227     _active_workers(n_workers)
5228   {
5229     assert(n_workers > 0, "shouldn't call this otherwise");
5230   }
5231 
5232   // Executes the given task using concurrent marking worker threads.
5233   virtual void execute(ProcessTask& task);
5234   virtual void execute(EnqueueTask& task);
5235 };
5236 
5237 // Gang task for possibly parallel reference processing
5238 
5239 class G1STWRefProcTaskProxy: public AbstractGangTask {
5240   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5241   ProcessTask&     _proc_task;
5242   G1CollectedHeap* _g1h;
5243   RefToScanQueueSet *_task_queues;
5244   ParallelTaskTerminator* _terminator;
5245 
5246 public:
5247   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5248                      G1CollectedHeap* g1h,
5249                      RefToScanQueueSet *task_queues,
5250                      ParallelTaskTerminator* terminator) :
5251     AbstractGangTask("Process reference objects in parallel"),
5252     _proc_task(proc_task),
5253     _g1h(g1h),
5254     _task_queues(task_queues),
5255     _terminator(terminator)
5256   {}
5257 
5258   virtual void work(uint worker_id) {
5259     // The reference processing task executed by a single worker.
5260     ResourceMark rm;
5261     HandleMark   hm;
5262 
5263     G1STWIsAliveClosure is_alive(_g1h);
5264 
5265     G1ParScanThreadState pss(_g1h, worker_id);
5266 
5267     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5268     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5269     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5270 
5271     pss.set_evac_closure(&scan_evac_cl);
5272     pss.set_evac_failure_closure(&evac_failure_cl);
5273     pss.set_partial_scan_closure(&partial_scan_cl);
5274 
5275     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5276     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5277 
5278     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5279     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5280 
5281     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5282     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5283 
5284     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5285       // We also need to mark copied objects.
5286       copy_non_heap_cl = &copy_mark_non_heap_cl;
5287       copy_metadata_cl = &copy_mark_metadata_cl;
5288     }
5289 
5290     // Keep alive closure.
5291     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5292 
5293     // Complete GC closure
5294     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5295 
5296     // Call the reference processing task's work routine.
5297     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5298 
5299     // Note we cannot assert that the refs array is empty here as not all
5300     // of the processing tasks (specifically phase2 - pp2_work) execute
5301     // the complete_gc closure (which ordinarily would drain the queue) so
5302     // the queue may not be empty.
5303   }
5304 };
5305 
5306 // Driver routine for parallel reference processing.
5307 // Creates an instance of the ref processing gang
5308 // task and has the worker threads execute it.
5309 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5310   assert(_workers != NULL, "Need parallel worker threads.");
5311 
5312   ParallelTaskTerminator terminator(_active_workers, _queues);
5313   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5314 
5315   _g1h->set_par_threads(_active_workers);
5316   _workers->run_task(&proc_task_proxy);
5317   _g1h->set_par_threads(0);
5318 }
5319 
5320 // Gang task for parallel reference enqueueing.
5321 
5322 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5323   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5324   EnqueueTask& _enq_task;
5325 
5326 public:
5327   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5328     AbstractGangTask("Enqueue reference objects in parallel"),
5329     _enq_task(enq_task)
5330   { }
5331 
5332   virtual void work(uint worker_id) {
5333     _enq_task.work(worker_id);
5334   }
5335 };
5336 
5337 // Driver routine for parallel reference enqueing.
5338 // Creates an instance of the ref enqueueing gang
5339 // task and has the worker threads execute it.
5340 
5341 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5342   assert(_workers != NULL, "Need parallel worker threads.");
5343 
5344   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5345 
5346   _g1h->set_par_threads(_active_workers);
5347   _workers->run_task(&enq_task_proxy);
5348   _g1h->set_par_threads(0);
5349 }
5350 
5351 // End of weak reference support closures
5352 
5353 // Abstract task used to preserve (i.e. copy) any referent objects
5354 // that are in the collection set and are pointed to by reference
5355 // objects discovered by the CM ref processor.
5356 
5357 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5358 protected:
5359   G1CollectedHeap* _g1h;
5360   RefToScanQueueSet      *_queues;
5361   ParallelTaskTerminator _terminator;
5362   uint _n_workers;
5363 
5364 public:
5365   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5366     AbstractGangTask("ParPreserveCMReferents"),
5367     _g1h(g1h),
5368     _queues(task_queues),
5369     _terminator(workers, _queues),
5370     _n_workers(workers)
5371   { }
5372 
5373   void work(uint worker_id) {
5374     ResourceMark rm;
5375     HandleMark   hm;
5376 
5377     G1ParScanThreadState            pss(_g1h, worker_id);
5378     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5379     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5380     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5381 
5382     pss.set_evac_closure(&scan_evac_cl);
5383     pss.set_evac_failure_closure(&evac_failure_cl);
5384     pss.set_partial_scan_closure(&partial_scan_cl);
5385 
5386     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5387 
5388 
5389     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5390     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5391 
5392     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5393     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5394 
5395     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5396     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5397 
5398     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5399       // We also need to mark copied objects.
5400       copy_non_heap_cl = &copy_mark_non_heap_cl;
5401       copy_metadata_cl = &copy_mark_metadata_cl;
5402     }
5403 
5404     // Is alive closure
5405     G1AlwaysAliveClosure always_alive(_g1h);
5406 
5407     // Copying keep alive closure. Applied to referent objects that need
5408     // to be copied.
5409     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5410 
5411     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5412 
5413     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5414     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5415 
5416     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5417     // So this must be true - but assert just in case someone decides to
5418     // change the worker ids.
5419     assert(0 <= worker_id && worker_id < limit, "sanity");
5420     assert(!rp->discovery_is_atomic(), "check this code");
5421 
5422     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5423     for (uint idx = worker_id; idx < limit; idx += stride) {
5424       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5425 
5426       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5427       while (iter.has_next()) {
5428         // Since discovery is not atomic for the CM ref processor, we
5429         // can see some null referent objects.
5430         iter.load_ptrs(DEBUG_ONLY(true));
5431         oop ref = iter.obj();
5432 
5433         // This will filter nulls.
5434         if (iter.is_referent_alive()) {
5435           iter.make_referent_alive();
5436         }
5437         iter.move_to_next();
5438       }
5439     }
5440 
5441     // Drain the queue - which may cause stealing
5442     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5443     drain_queue.do_void();
5444     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5445     assert(pss.refs()->is_empty(), "should be");
5446   }
5447 };
5448 
5449 // Weak Reference processing during an evacuation pause (part 1).
5450 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5451   double ref_proc_start = os::elapsedTime();
5452 
5453   ReferenceProcessor* rp = _ref_processor_stw;
5454   assert(rp->discovery_enabled(), "should have been enabled");
5455 
5456   // Any reference objects, in the collection set, that were 'discovered'
5457   // by the CM ref processor should have already been copied (either by
5458   // applying the external root copy closure to the discovered lists, or
5459   // by following an RSet entry).
5460   //
5461   // But some of the referents, that are in the collection set, that these
5462   // reference objects point to may not have been copied: the STW ref
5463   // processor would have seen that the reference object had already
5464   // been 'discovered' and would have skipped discovering the reference,
5465   // but would not have treated the reference object as a regular oop.
5466   // As a reult the copy closure would not have been applied to the
5467   // referent object.
5468   //
5469   // We need to explicitly copy these referent objects - the references
5470   // will be processed at the end of remarking.
5471   //
5472   // We also need to do this copying before we process the reference
5473   // objects discovered by the STW ref processor in case one of these
5474   // referents points to another object which is also referenced by an
5475   // object discovered by the STW ref processor.
5476 
5477   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5478            no_of_gc_workers == workers()->active_workers(),
5479            "Need to reset active GC workers");
5480 
5481   set_par_threads(no_of_gc_workers);
5482   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5483                                                  no_of_gc_workers,
5484                                                  _task_queues);
5485 
5486   if (G1CollectedHeap::use_parallel_gc_threads()) {
5487     workers()->run_task(&keep_cm_referents);
5488   } else {
5489     keep_cm_referents.work(0);
5490   }
5491 
5492   set_par_threads(0);
5493 
5494   // Closure to test whether a referent is alive.
5495   G1STWIsAliveClosure is_alive(this);
5496 
5497   // Even when parallel reference processing is enabled, the processing
5498   // of JNI refs is serial and performed serially by the current thread
5499   // rather than by a worker. The following PSS will be used for processing
5500   // JNI refs.
5501 
5502   // Use only a single queue for this PSS.
5503   G1ParScanThreadState pss(this, 0);
5504 
5505   // We do not embed a reference processor in the copying/scanning
5506   // closures while we're actually processing the discovered
5507   // reference objects.
5508   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5509   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5510   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5511 
5512   pss.set_evac_closure(&scan_evac_cl);
5513   pss.set_evac_failure_closure(&evac_failure_cl);
5514   pss.set_partial_scan_closure(&partial_scan_cl);
5515 
5516   assert(pss.refs()->is_empty(), "pre-condition");
5517 
5518   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5519   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5520 
5521   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5522   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5523 
5524   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5525   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5526 
5527   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5528     // We also need to mark copied objects.
5529     copy_non_heap_cl = &copy_mark_non_heap_cl;
5530     copy_metadata_cl = &copy_mark_metadata_cl;
5531   }
5532 
5533   // Keep alive closure.
5534   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5535 
5536   // Serial Complete GC closure
5537   G1STWDrainQueueClosure drain_queue(this, &pss);
5538 
5539   // Setup the soft refs policy...
5540   rp->setup_policy(false);
5541 
5542   if (!rp->processing_is_mt()) {
5543     // Serial reference processing...
5544     rp->process_discovered_references(&is_alive,
5545                                       &keep_alive,
5546                                       &drain_queue,
5547                                       NULL);
5548   } else {
5549     // Parallel reference processing
5550     assert(rp->num_q() == no_of_gc_workers, "sanity");
5551     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5552 
5553     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5554     rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5555   }
5556 
5557   // We have completed copying any necessary live referent objects
5558   // (that were not copied during the actual pause) so we can
5559   // retire any active alloc buffers
5560   pss.retire_alloc_buffers();
5561   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5562 
5563   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5564   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5565 }
5566 
5567 // Weak Reference processing during an evacuation pause (part 2).
5568 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5569   double ref_enq_start = os::elapsedTime();
5570 
5571   ReferenceProcessor* rp = _ref_processor_stw;
5572   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5573 
5574   // Now enqueue any remaining on the discovered lists on to
5575   // the pending list.
5576   if (!rp->processing_is_mt()) {
5577     // Serial reference processing...
5578     rp->enqueue_discovered_references();
5579   } else {
5580     // Parallel reference enqueuing
5581 
5582     assert(no_of_gc_workers == workers()->active_workers(),
5583            "Need to reset active workers");
5584     assert(rp->num_q() == no_of_gc_workers, "sanity");
5585     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5586 
5587     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5588     rp->enqueue_discovered_references(&par_task_executor);
5589   }
5590 
5591   rp->verify_no_references_recorded();
5592   assert(!rp->discovery_enabled(), "should have been disabled");
5593 
5594   // FIXME
5595   // CM's reference processing also cleans up the string and symbol tables.
5596   // Should we do that here also? We could, but it is a serial operation
5597   // and could signicantly increase the pause time.
5598 
5599   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5600   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5601 }
5602 
5603 void G1CollectedHeap::evacuate_collection_set() {
5604   _expand_heap_after_alloc_failure = true;
5605   set_evacuation_failed(false);
5606 
5607   // Should G1EvacuationFailureALot be in effect for this GC?
5608   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5609 
5610   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5611 
5612   // Disable the hot card cache.
5613   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5614   hot_card_cache->reset_hot_cache_claimed_index();
5615   hot_card_cache->set_use_cache(false);
5616 
5617   uint n_workers;
5618   if (G1CollectedHeap::use_parallel_gc_threads()) {
5619     n_workers =
5620       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5621                                      workers()->active_workers(),
5622                                      Threads::number_of_non_daemon_threads());
5623     assert(UseDynamicNumberOfGCThreads ||
5624            n_workers == workers()->total_workers(),
5625            "If not dynamic should be using all the  workers");
5626     workers()->set_active_workers(n_workers);
5627     set_par_threads(n_workers);
5628   } else {
5629     assert(n_par_threads() == 0,
5630            "Should be the original non-parallel value");
5631     n_workers = 1;
5632   }
5633 
5634   G1ParTask g1_par_task(this, _task_queues);
5635 
5636   init_for_evac_failure(NULL);
5637 
5638   rem_set()->prepare_for_younger_refs_iterate(true);
5639 
5640   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5641   double start_par_time_sec = os::elapsedTime();
5642   double end_par_time_sec;
5643 
5644   {
5645     StrongRootsScope srs(this);
5646 
5647     if (G1CollectedHeap::use_parallel_gc_threads()) {
5648       // The individual threads will set their evac-failure closures.
5649       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5650       // These tasks use ShareHeap::_process_strong_tasks
5651       assert(UseDynamicNumberOfGCThreads ||
5652              workers()->active_workers() == workers()->total_workers(),
5653              "If not dynamic should be using all the  workers");
5654       workers()->run_task(&g1_par_task);
5655     } else {
5656       g1_par_task.set_for_termination(n_workers);
5657       g1_par_task.work(0);
5658     }
5659     end_par_time_sec = os::elapsedTime();
5660 
5661     // Closing the inner scope will execute the destructor
5662     // for the StrongRootsScope object. We record the current
5663     // elapsed time before closing the scope so that time
5664     // taken for the SRS destructor is NOT included in the
5665     // reported parallel time.
5666   }
5667 
5668   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5669   g1_policy()->phase_times()->record_par_time(par_time_ms);
5670 
5671   double code_root_fixup_time_ms =
5672         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5673   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5674 
5675   set_par_threads(0);
5676 
5677   // Process any discovered reference objects - we have
5678   // to do this _before_ we retire the GC alloc regions
5679   // as we may have to copy some 'reachable' referent
5680   // objects (and their reachable sub-graphs) that were
5681   // not copied during the pause.
5682   process_discovered_references(n_workers);
5683 
5684   // Weak root processing.
5685   // Note: when JSR 292 is enabled and code blobs can contain
5686   // non-perm oops then we will need to process the code blobs
5687   // here too.
5688   {
5689     G1STWIsAliveClosure is_alive(this);
5690     G1KeepAliveClosure keep_alive(this);
5691     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5692   }
5693 
5694   release_gc_alloc_regions(n_workers);
5695   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5696  
5697   // Reset and re-enable the hot card cache.
5698   // Note the counts for the cards in the regions in the
5699   // collection set are reset when the collection set is freed.
5700   hot_card_cache->reset_hot_cache();
5701   hot_card_cache->set_use_cache(true);
5702 
5703   finalize_for_evac_failure();
5704 
5705   if (evacuation_failed()) {
5706     remove_self_forwarding_pointers();
5707 
5708     // Reset the G1EvacuationFailureALot counters and flags
5709     // Note: the values are reset only when an actual
5710     // evacuation failure occurs.
5711     NOT_PRODUCT(reset_evacuation_should_fail();)
5712   }
5713 
5714   // Enqueue any remaining references remaining on the STW
5715   // reference processor's discovered lists. We need to do
5716   // this after the card table is cleaned (and verified) as
5717   // the act of enqueuing entries on to the pending list
5718   // will log these updates (and dirty their associated
5719   // cards). We need these updates logged to update any
5720   // RSets.
5721   enqueue_discovered_references(n_workers);
5722 
5723   if (G1DeferredRSUpdate) {
5724     RedirtyLoggedCardTableEntryFastClosure redirty;
5725     dirty_card_queue_set().set_closure(&redirty);
5726     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5727 
5728     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5729     dcq.merge_bufferlists(&dirty_card_queue_set());
5730     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5731   }
5732   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5733 }
5734 
5735 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5736                                      size_t* pre_used,
5737                                      FreeRegionList* free_list,
5738                                      OldRegionSet* old_proxy_set,
5739                                      HumongousRegionSet* humongous_proxy_set,
5740                                      HRRSCleanupTask* hrrs_cleanup_task,
5741                                      bool par) {
5742   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5743     if (hr->isHumongous()) {
5744       assert(hr->startsHumongous(), "we should only see starts humongous");
5745       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5746     } else {
5747       _old_set.remove_with_proxy(hr, old_proxy_set);
5748       free_region(hr, pre_used, free_list, par);
5749     }
5750   } else {
5751     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5752   }
5753 }
5754 
5755 void G1CollectedHeap::free_region(HeapRegion* hr,
5756                                   size_t* pre_used,
5757                                   FreeRegionList* free_list,
5758                                   bool par) {
5759   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5760   assert(!hr->is_empty(), "the region should not be empty");
5761   assert(free_list != NULL, "pre-condition");
5762 
5763   // Clear the card counts for this region.
5764   // Note: we only need to do this if the region is not young
5765   // (since we don't refine cards in young regions).
5766   if (!hr->is_young()) {
5767     _cg1r->hot_card_cache()->reset_card_counts(hr);
5768   }
5769   *pre_used += hr->used();
5770   hr->hr_clear(par, true /* clear_space */);
5771   free_list->add_as_head(hr);
5772 }
5773 
5774 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5775                                      size_t* pre_used,
5776                                      FreeRegionList* free_list,
5777                                      HumongousRegionSet* humongous_proxy_set,
5778                                      bool par) {
5779   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5780   assert(free_list != NULL, "pre-condition");
5781   assert(humongous_proxy_set != NULL, "pre-condition");
5782 
5783   size_t hr_used = hr->used();
5784   size_t hr_capacity = hr->capacity();
5785   size_t hr_pre_used = 0;
5786   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5787   // We need to read this before we make the region non-humongous,
5788   // otherwise the information will be gone.
5789   uint last_index = hr->last_hc_index();
5790   hr->set_notHumongous();
5791   free_region(hr, &hr_pre_used, free_list, par);
5792 
5793   uint i = hr->hrs_index() + 1;
5794   while (i < last_index) {
5795     HeapRegion* curr_hr = region_at(i);
5796     assert(curr_hr->continuesHumongous(), "invariant");
5797     curr_hr->set_notHumongous();
5798     free_region(curr_hr, &hr_pre_used, free_list, par);
5799     i += 1;
5800   }
5801   assert(hr_pre_used == hr_used,
5802          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5803                  "should be the same", hr_pre_used, hr_used));
5804   *pre_used += hr_pre_used;
5805 }
5806 
5807 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5808                                        FreeRegionList* free_list,
5809                                        OldRegionSet* old_proxy_set,
5810                                        HumongousRegionSet* humongous_proxy_set,
5811                                        bool par) {
5812   if (pre_used > 0) {
5813     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5814     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5815     assert(_summary_bytes_used >= pre_used,
5816            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5817                    "should be >= pre_used: "SIZE_FORMAT,
5818                    _summary_bytes_used, pre_used));
5819     _summary_bytes_used -= pre_used;
5820   }
5821   if (free_list != NULL && !free_list->is_empty()) {
5822     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5823     _free_list.add_as_head(free_list);
5824   }
5825   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5826     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5827     _old_set.update_from_proxy(old_proxy_set);
5828   }
5829   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5830     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5831     _humongous_set.update_from_proxy(humongous_proxy_set);
5832   }
5833 }
5834 
5835 class G1ParCleanupCTTask : public AbstractGangTask {
5836   CardTableModRefBS* _ct_bs;
5837   G1CollectedHeap* _g1h;
5838   HeapRegion* volatile _su_head;
5839 public:
5840   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5841                      G1CollectedHeap* g1h) :
5842     AbstractGangTask("G1 Par Cleanup CT Task"),
5843     _ct_bs(ct_bs), _g1h(g1h) { }
5844 
5845   void work(uint worker_id) {
5846     HeapRegion* r;
5847     while (r = _g1h->pop_dirty_cards_region()) {
5848       clear_cards(r);
5849     }
5850   }
5851 
5852   void clear_cards(HeapRegion* r) {
5853     // Cards of the survivors should have already been dirtied.
5854     if (!r->is_survivor()) {
5855       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5856     }
5857   }
5858 };
5859 
5860 #ifndef PRODUCT
5861 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5862   G1CollectedHeap* _g1h;
5863   CardTableModRefBS* _ct_bs;
5864 public:
5865   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5866     : _g1h(g1h), _ct_bs(ct_bs) { }
5867   virtual bool doHeapRegion(HeapRegion* r) {
5868     if (r->is_survivor()) {
5869       _g1h->verify_dirty_region(r);
5870     } else {
5871       _g1h->verify_not_dirty_region(r);
5872     }
5873     return false;
5874   }
5875 };
5876 
5877 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5878   // All of the region should be clean.
5879   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5880   MemRegion mr(hr->bottom(), hr->end());
5881   ct_bs->verify_not_dirty_region(mr);
5882 }
5883 
5884 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5885   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5886   // dirty allocated blocks as they allocate them. The thread that
5887   // retires each region and replaces it with a new one will do a
5888   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5889   // not dirty that area (one less thing to have to do while holding
5890   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5891   // is dirty.
5892   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5893   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5894   ct_bs->verify_dirty_region(mr);
5895 }
5896 
5897 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5898   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5899   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5900     verify_dirty_region(hr);
5901   }
5902 }
5903 
5904 void G1CollectedHeap::verify_dirty_young_regions() {
5905   verify_dirty_young_list(_young_list->first_region());
5906 }
5907 #endif
5908 
5909 void G1CollectedHeap::cleanUpCardTable() {
5910   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5911   double start = os::elapsedTime();
5912 
5913   {
5914     // Iterate over the dirty cards region list.
5915     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5916 
5917     if (G1CollectedHeap::use_parallel_gc_threads()) {
5918       set_par_threads();
5919       workers()->run_task(&cleanup_task);
5920       set_par_threads(0);
5921     } else {
5922       while (_dirty_cards_region_list) {
5923         HeapRegion* r = _dirty_cards_region_list;
5924         cleanup_task.clear_cards(r);
5925         _dirty_cards_region_list = r->get_next_dirty_cards_region();
5926         if (_dirty_cards_region_list == r) {
5927           // The last region.
5928           _dirty_cards_region_list = NULL;
5929         }
5930         r->set_next_dirty_cards_region(NULL);
5931       }
5932     }
5933 #ifndef PRODUCT
5934     if (G1VerifyCTCleanup || VerifyAfterGC) {
5935       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5936       heap_region_iterate(&cleanup_verifier);
5937     }
5938 #endif
5939   }
5940 
5941   double elapsed = os::elapsedTime() - start;
5942   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5943 }
5944 
5945 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5946   size_t pre_used = 0;
5947   FreeRegionList local_free_list("Local List for CSet Freeing");
5948 
5949   double young_time_ms     = 0.0;
5950   double non_young_time_ms = 0.0;
5951 
5952   // Since the collection set is a superset of the the young list,
5953   // all we need to do to clear the young list is clear its
5954   // head and length, and unlink any young regions in the code below
5955   _young_list->clear();
5956 
5957   G1CollectorPolicy* policy = g1_policy();
5958 
5959   double start_sec = os::elapsedTime();
5960   bool non_young = true;
5961 
5962   HeapRegion* cur = cs_head;
5963   int age_bound = -1;
5964   size_t rs_lengths = 0;
5965 
5966   while (cur != NULL) {
5967     assert(!is_on_master_free_list(cur), "sanity");
5968     if (non_young) {
5969       if (cur->is_young()) {
5970         double end_sec = os::elapsedTime();
5971         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5972         non_young_time_ms += elapsed_ms;
5973 
5974         start_sec = os::elapsedTime();
5975         non_young = false;
5976       }
5977     } else {
5978       if (!cur->is_young()) {
5979         double end_sec = os::elapsedTime();
5980         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5981         young_time_ms += elapsed_ms;
5982 
5983         start_sec = os::elapsedTime();
5984         non_young = true;
5985       }
5986     }
5987 
5988     rs_lengths += cur->rem_set()->occupied();
5989 
5990     HeapRegion* next = cur->next_in_collection_set();
5991     assert(cur->in_collection_set(), "bad CS");
5992     cur->set_next_in_collection_set(NULL);
5993     cur->set_in_collection_set(false);
5994 
5995     if (cur->is_young()) {
5996       int index = cur->young_index_in_cset();
5997       assert(index != -1, "invariant");
5998       assert((uint) index < policy->young_cset_region_length(), "invariant");
5999       size_t words_survived = _surviving_young_words[index];
6000       cur->record_surv_words_in_group(words_survived);
6001 
6002       // At this point the we have 'popped' cur from the collection set
6003       // (linked via next_in_collection_set()) but it is still in the
6004       // young list (linked via next_young_region()). Clear the
6005       // _next_young_region field.
6006       cur->set_next_young_region(NULL);
6007     } else {
6008       int index = cur->young_index_in_cset();
6009       assert(index == -1, "invariant");
6010     }
6011 
6012     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6013             (!cur->is_young() && cur->young_index_in_cset() == -1),
6014             "invariant" );
6015 
6016     if (!cur->evacuation_failed()) {
6017       MemRegion used_mr = cur->used_region();
6018 
6019       // And the region is empty.
6020       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6021       free_region(cur, &pre_used, &local_free_list, false /* par */);
6022     } else {
6023       cur->uninstall_surv_rate_group();
6024       if (cur->is_young()) {
6025         cur->set_young_index_in_cset(-1);
6026       }
6027       cur->set_not_young();
6028       cur->set_evacuation_failed(false);
6029       // The region is now considered to be old.
6030       _old_set.add(cur);
6031     }
6032     cur = next;
6033   }
6034 
6035   policy->record_max_rs_lengths(rs_lengths);
6036   policy->cset_regions_freed();
6037 
6038   double end_sec = os::elapsedTime();
6039   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6040 
6041   if (non_young) {
6042     non_young_time_ms += elapsed_ms;
6043   } else {
6044     young_time_ms += elapsed_ms;
6045   }
6046 
6047   update_sets_after_freeing_regions(pre_used, &local_free_list,
6048                                     NULL /* old_proxy_set */,
6049                                     NULL /* humongous_proxy_set */,
6050                                     false /* par */);
6051   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6052   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6053 }
6054 
6055 // This routine is similar to the above but does not record
6056 // any policy statistics or update free lists; we are abandoning
6057 // the current incremental collection set in preparation of a
6058 // full collection. After the full GC we will start to build up
6059 // the incremental collection set again.
6060 // This is only called when we're doing a full collection
6061 // and is immediately followed by the tearing down of the young list.
6062 
6063 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6064   HeapRegion* cur = cs_head;
6065 
6066   while (cur != NULL) {
6067     HeapRegion* next = cur->next_in_collection_set();
6068     assert(cur->in_collection_set(), "bad CS");
6069     cur->set_next_in_collection_set(NULL);
6070     cur->set_in_collection_set(false);
6071     cur->set_young_index_in_cset(-1);
6072     cur = next;
6073   }
6074 }
6075 
6076 void G1CollectedHeap::set_free_regions_coming() {
6077   if (G1ConcRegionFreeingVerbose) {
6078     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6079                            "setting free regions coming");
6080   }
6081 
6082   assert(!free_regions_coming(), "pre-condition");
6083   _free_regions_coming = true;
6084 }
6085 
6086 void G1CollectedHeap::reset_free_regions_coming() {
6087   assert(free_regions_coming(), "pre-condition");
6088 
6089   {
6090     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6091     _free_regions_coming = false;
6092     SecondaryFreeList_lock->notify_all();
6093   }
6094 
6095   if (G1ConcRegionFreeingVerbose) {
6096     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6097                            "reset free regions coming");
6098   }
6099 }
6100 
6101 void G1CollectedHeap::wait_while_free_regions_coming() {
6102   // Most of the time we won't have to wait, so let's do a quick test
6103   // first before we take the lock.
6104   if (!free_regions_coming()) {
6105     return;
6106   }
6107 
6108   if (G1ConcRegionFreeingVerbose) {
6109     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6110                            "waiting for free regions");
6111   }
6112 
6113   {
6114     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6115     while (free_regions_coming()) {
6116       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6117     }
6118   }
6119 
6120   if (G1ConcRegionFreeingVerbose) {
6121     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6122                            "done waiting for free regions");
6123   }
6124 }
6125 
6126 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6127   assert(heap_lock_held_for_gc(),
6128               "the heap lock should already be held by or for this thread");
6129   _young_list->push_region(hr);
6130 }
6131 
6132 class NoYoungRegionsClosure: public HeapRegionClosure {
6133 private:
6134   bool _success;
6135 public:
6136   NoYoungRegionsClosure() : _success(true) { }
6137   bool doHeapRegion(HeapRegion* r) {
6138     if (r->is_young()) {
6139       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6140                              r->bottom(), r->end());
6141       _success = false;
6142     }
6143     return false;
6144   }
6145   bool success() { return _success; }
6146 };
6147 
6148 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6149   bool ret = _young_list->check_list_empty(check_sample);
6150 
6151   if (check_heap) {
6152     NoYoungRegionsClosure closure;
6153     heap_region_iterate(&closure);
6154     ret = ret && closure.success();
6155   }
6156 
6157   return ret;
6158 }
6159 
6160 class TearDownRegionSetsClosure : public HeapRegionClosure {
6161 private:
6162   OldRegionSet *_old_set;
6163 
6164 public:
6165   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6166 
6167   bool doHeapRegion(HeapRegion* r) {
6168     if (r->is_empty()) {
6169       // We ignore empty regions, we'll empty the free list afterwards
6170     } else if (r->is_young()) {
6171       // We ignore young regions, we'll empty the young list afterwards
6172     } else if (r->isHumongous()) {
6173       // We ignore humongous regions, we're not tearing down the
6174       // humongous region set
6175     } else {
6176       // The rest should be old
6177       _old_set->remove(r);
6178     }
6179     return false;
6180   }
6181 
6182   ~TearDownRegionSetsClosure() {
6183     assert(_old_set->is_empty(), "post-condition");
6184   }
6185 };
6186 
6187 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6188   assert_at_safepoint(true /* should_be_vm_thread */);
6189 
6190   if (!free_list_only) {
6191     TearDownRegionSetsClosure cl(&_old_set);
6192     heap_region_iterate(&cl);
6193 
6194     // Need to do this after the heap iteration to be able to
6195     // recognize the young regions and ignore them during the iteration.
6196     _young_list->empty_list();
6197   }
6198   _free_list.remove_all();
6199 }
6200 
6201 class RebuildRegionSetsClosure : public HeapRegionClosure {
6202 private:
6203   bool            _free_list_only;
6204   OldRegionSet*   _old_set;
6205   FreeRegionList* _free_list;
6206   size_t          _total_used;
6207 
6208 public:
6209   RebuildRegionSetsClosure(bool free_list_only,
6210                            OldRegionSet* old_set, FreeRegionList* free_list) :
6211     _free_list_only(free_list_only),
6212     _old_set(old_set), _free_list(free_list), _total_used(0) {
6213     assert(_free_list->is_empty(), "pre-condition");
6214     if (!free_list_only) {
6215       assert(_old_set->is_empty(), "pre-condition");
6216     }
6217   }
6218 
6219   bool doHeapRegion(HeapRegion* r) {
6220     if (r->continuesHumongous()) {
6221       return false;
6222     }
6223 
6224     if (r->is_empty()) {
6225       // Add free regions to the free list
6226       _free_list->add_as_tail(r);
6227     } else if (!_free_list_only) {
6228       assert(!r->is_young(), "we should not come across young regions");
6229 
6230       if (r->isHumongous()) {
6231         // We ignore humongous regions, we left the humongous set unchanged
6232       } else {
6233         // The rest should be old, add them to the old set
6234         _old_set->add(r);
6235       }
6236       _total_used += r->used();
6237     }
6238 
6239     return false;
6240   }
6241 
6242   size_t total_used() {
6243     return _total_used;
6244   }
6245 };
6246 
6247 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6248   assert_at_safepoint(true /* should_be_vm_thread */);
6249 
6250   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6251   heap_region_iterate(&cl);
6252 
6253   if (!free_list_only) {
6254     _summary_bytes_used = cl.total_used();
6255   }
6256   assert(_summary_bytes_used == recalculate_used(),
6257          err_msg("inconsistent _summary_bytes_used, "
6258                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6259                  _summary_bytes_used, recalculate_used()));
6260 }
6261 
6262 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6263   _refine_cte_cl->set_concurrent(concurrent);
6264 }
6265 
6266 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6267   HeapRegion* hr = heap_region_containing(p);
6268   if (hr == NULL) {
6269     return false;
6270   } else {
6271     return hr->is_in(p);
6272   }
6273 }
6274 
6275 // Methods for the mutator alloc region
6276 
6277 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6278                                                       bool force) {
6279   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6280   assert(!force || g1_policy()->can_expand_young_list(),
6281          "if force is true we should be able to expand the young list");
6282   bool young_list_full = g1_policy()->is_young_list_full();
6283   if (force || !young_list_full) {
6284     HeapRegion* new_alloc_region = new_region(word_size,
6285                                               false /* do_expand */);
6286     if (new_alloc_region != NULL) {
6287       set_region_short_lived_locked(new_alloc_region);
6288       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6289       return new_alloc_region;
6290     }
6291   }
6292   return NULL;
6293 }
6294 
6295 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6296                                                   size_t allocated_bytes) {
6297   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6298   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6299 
6300   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6301   _summary_bytes_used += allocated_bytes;
6302   _hr_printer.retire(alloc_region);
6303   // We update the eden sizes here, when the region is retired,
6304   // instead of when it's allocated, since this is the point that its
6305   // used space has been recored in _summary_bytes_used.
6306   g1mm()->update_eden_size();
6307 }
6308 
6309 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6310                                                     bool force) {
6311   return _g1h->new_mutator_alloc_region(word_size, force);
6312 }
6313 
6314 void G1CollectedHeap::set_par_threads() {
6315   // Don't change the number of workers.  Use the value previously set
6316   // in the workgroup.
6317   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6318   uint n_workers = workers()->active_workers();
6319   assert(UseDynamicNumberOfGCThreads ||
6320            n_workers == workers()->total_workers(),
6321       "Otherwise should be using the total number of workers");
6322   if (n_workers == 0) {
6323     assert(false, "Should have been set in prior evacuation pause.");
6324     n_workers = ParallelGCThreads;
6325     workers()->set_active_workers(n_workers);
6326   }
6327   set_par_threads(n_workers);
6328 }
6329 
6330 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6331                                        size_t allocated_bytes) {
6332   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6333 }
6334 
6335 // Methods for the GC alloc regions
6336 
6337 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6338                                                  uint count,
6339                                                  GCAllocPurpose ap) {
6340   assert(FreeList_lock->owned_by_self(), "pre-condition");
6341 
6342   if (count < g1_policy()->max_regions(ap)) {
6343     HeapRegion* new_alloc_region = new_region(word_size,
6344                                               true /* do_expand */);
6345     if (new_alloc_region != NULL) {
6346       // We really only need to do this for old regions given that we
6347       // should never scan survivors. But it doesn't hurt to do it
6348       // for survivors too.
6349       new_alloc_region->set_saved_mark();
6350       if (ap == GCAllocForSurvived) {
6351         new_alloc_region->set_survivor();
6352         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6353       } else {
6354         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6355       }
6356       bool during_im = g1_policy()->during_initial_mark_pause();
6357       new_alloc_region->note_start_of_copying(during_im);
6358       return new_alloc_region;
6359     } else {
6360       g1_policy()->note_alloc_region_limit_reached(ap);
6361     }
6362   }
6363   return NULL;
6364 }
6365 
6366 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6367                                              size_t allocated_bytes,
6368                                              GCAllocPurpose ap) {
6369   bool during_im = g1_policy()->during_initial_mark_pause();
6370   alloc_region->note_end_of_copying(during_im);
6371   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6372   if (ap == GCAllocForSurvived) {
6373     young_list()->add_survivor_region(alloc_region);
6374   } else {
6375     _old_set.add(alloc_region);
6376   }
6377   _hr_printer.retire(alloc_region);
6378 }
6379 
6380 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6381                                                        bool force) {
6382   assert(!force, "not supported for GC alloc regions");
6383   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6384 }
6385 
6386 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6387                                           size_t allocated_bytes) {
6388   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6389                                GCAllocForSurvived);
6390 }
6391 
6392 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6393                                                   bool force) {
6394   assert(!force, "not supported for GC alloc regions");
6395   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6396 }
6397 
6398 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6399                                      size_t allocated_bytes) {
6400   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6401                                GCAllocForTenured);
6402 }
6403 // Heap region set verification
6404 
6405 class VerifyRegionListsClosure : public HeapRegionClosure {
6406 private:
6407   FreeRegionList*     _free_list;
6408   OldRegionSet*       _old_set;
6409   HumongousRegionSet* _humongous_set;
6410   uint                _region_count;
6411 
6412 public:
6413   VerifyRegionListsClosure(OldRegionSet* old_set,
6414                            HumongousRegionSet* humongous_set,
6415                            FreeRegionList* free_list) :
6416     _old_set(old_set), _humongous_set(humongous_set),
6417     _free_list(free_list), _region_count(0) { }
6418 
6419   uint region_count() { return _region_count; }
6420 
6421   bool doHeapRegion(HeapRegion* hr) {
6422     _region_count += 1;
6423 
6424     if (hr->continuesHumongous()) {
6425       return false;
6426     }
6427 
6428     if (hr->is_young()) {
6429       // TODO
6430     } else if (hr->startsHumongous()) {
6431       _humongous_set->verify_next_region(hr);
6432     } else if (hr->is_empty()) {
6433       _free_list->verify_next_region(hr);
6434     } else {
6435       _old_set->verify_next_region(hr);
6436     }
6437     return false;
6438   }
6439 };
6440 
6441 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6442                                              HeapWord* bottom) {
6443   HeapWord* end = bottom + HeapRegion::GrainWords;
6444   MemRegion mr(bottom, end);
6445   assert(_g1_reserved.contains(mr), "invariant");
6446   // This might return NULL if the allocation fails
6447   return new HeapRegion(hrs_index, _bot_shared, mr);
6448 }
6449 
6450 void G1CollectedHeap::verify_region_sets() {
6451   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6452 
6453   // First, check the explicit lists.
6454   _free_list.verify();
6455   {
6456     // Given that a concurrent operation might be adding regions to
6457     // the secondary free list we have to take the lock before
6458     // verifying it.
6459     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6460     _secondary_free_list.verify();
6461   }
6462   _old_set.verify();
6463   _humongous_set.verify();
6464 
6465   // If a concurrent region freeing operation is in progress it will
6466   // be difficult to correctly attributed any free regions we come
6467   // across to the correct free list given that they might belong to
6468   // one of several (free_list, secondary_free_list, any local lists,
6469   // etc.). So, if that's the case we will skip the rest of the
6470   // verification operation. Alternatively, waiting for the concurrent
6471   // operation to complete will have a non-trivial effect on the GC's
6472   // operation (no concurrent operation will last longer than the
6473   // interval between two calls to verification) and it might hide
6474   // any issues that we would like to catch during testing.
6475   if (free_regions_coming()) {
6476     return;
6477   }
6478 
6479   // Make sure we append the secondary_free_list on the free_list so
6480   // that all free regions we will come across can be safely
6481   // attributed to the free_list.
6482   append_secondary_free_list_if_not_empty_with_lock();
6483 
6484   // Finally, make sure that the region accounting in the lists is
6485   // consistent with what we see in the heap.
6486   _old_set.verify_start();
6487   _humongous_set.verify_start();
6488   _free_list.verify_start();
6489 
6490   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6491   heap_region_iterate(&cl);
6492 
6493   _old_set.verify_end();
6494   _humongous_set.verify_end();
6495   _free_list.verify_end();
6496 }