1 /*
   2  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "code/codeCache.hpp"
  27 #include "code/icBuffer.hpp"
  28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  36 #include "gc_implementation/g1/g1EvacFailure.hpp"
  37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  38 #include "gc_implementation/g1/g1Log.hpp"
  39 #include "gc_implementation/g1/g1MarkSweep.hpp"
  40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  42 #include "gc_implementation/g1/heapRegion.inline.hpp"
  43 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  45 #include "gc_implementation/g1/vm_operations_g1.hpp"
  46 #include "gc_implementation/shared/isGCActiveMark.hpp"
  47 #include "memory/gcLocker.inline.hpp"
  48 #include "memory/genOopClosures.inline.hpp"
  49 #include "memory/generationSpec.hpp"
  50 #include "memory/referenceProcessor.hpp"
  51 #include "oops/oop.inline.hpp"
  52 #include "oops/oop.pcgc.inline.hpp"
  53 #include "runtime/aprofiler.hpp"
  54 #include "runtime/vmThread.hpp"
  55 
  56 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  57 
  58 // turn it on so that the contents of the young list (scan-only /
  59 // to-be-collected) are printed at "strategic" points before / during
  60 // / after the collection --- this is useful for debugging
  61 #define YOUNG_LIST_VERBOSE 0
  62 // CURRENT STATUS
  63 // This file is under construction.  Search for "FIXME".
  64 
  65 // INVARIANTS/NOTES
  66 //
  67 // All allocation activity covered by the G1CollectedHeap interface is
  68 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  69 // and allocate_new_tlab, which are the "entry" points to the
  70 // allocation code from the rest of the JVM.  (Note that this does not
  71 // apply to TLAB allocation, which is not part of this interface: it
  72 // is done by clients of this interface.)
  73 
  74 // Notes on implementation of parallelism in different tasks.
  75 //
  76 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  77 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  78 // It does use run_task() which sets _n_workers in the task.
  79 // G1ParTask executes g1_process_strong_roots() ->
  80 // SharedHeap::process_strong_roots() which calls eventuall to
  81 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  82 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  83 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  84 //
  85 
  86 // Local to this file.
  87 
  88 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  89   SuspendibleThreadSet* _sts;
  90   G1RemSet* _g1rs;
  91   ConcurrentG1Refine* _cg1r;
  92   bool _concurrent;
  93 public:
  94   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  95                               G1RemSet* g1rs,
  96                               ConcurrentG1Refine* cg1r) :
  97     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
  98   {}
  99   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 100     bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
 101     // This path is executed by the concurrent refine or mutator threads,
 102     // concurrently, and so we do not care if card_ptr contains references
 103     // that point into the collection set.
 104     assert(!oops_into_cset, "should be");
 105 
 106     if (_concurrent && _sts->should_yield()) {
 107       // Caller will actually yield.
 108       return false;
 109     }
 110     // Otherwise, we finished successfully; return true.
 111     return true;
 112   }
 113   void set_concurrent(bool b) { _concurrent = b; }
 114 };
 115 
 116 
 117 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 118   int _calls;
 119   G1CollectedHeap* _g1h;
 120   CardTableModRefBS* _ctbs;
 121   int _histo[256];
 122 public:
 123   ClearLoggedCardTableEntryClosure() :
 124     _calls(0)
 125   {
 126     _g1h = G1CollectedHeap::heap();
 127     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 128     for (int i = 0; i < 256; i++) _histo[i] = 0;
 129   }
 130   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 131     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 132       _calls++;
 133       unsigned char* ujb = (unsigned char*)card_ptr;
 134       int ind = (int)(*ujb);
 135       _histo[ind]++;
 136       *card_ptr = -1;
 137     }
 138     return true;
 139   }
 140   int calls() { return _calls; }
 141   void print_histo() {
 142     gclog_or_tty->print_cr("Card table value histogram:");
 143     for (int i = 0; i < 256; i++) {
 144       if (_histo[i] != 0) {
 145         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 146       }
 147     }
 148   }
 149 };
 150 
 151 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 152   int _calls;
 153   G1CollectedHeap* _g1h;
 154   CardTableModRefBS* _ctbs;
 155 public:
 156   RedirtyLoggedCardTableEntryClosure() :
 157     _calls(0)
 158   {
 159     _g1h = G1CollectedHeap::heap();
 160     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 161   }
 162   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 163     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 164       _calls++;
 165       *card_ptr = 0;
 166     }
 167     return true;
 168   }
 169   int calls() { return _calls; }
 170 };
 171 
 172 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 173 public:
 174   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 175     *card_ptr = CardTableModRefBS::dirty_card_val();
 176     return true;
 177   }
 178 };
 179 
 180 YoungList::YoungList(G1CollectedHeap* g1h) :
 181     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 182     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 183   guarantee(check_list_empty(false), "just making sure...");
 184 }
 185 
 186 void YoungList::push_region(HeapRegion *hr) {
 187   assert(!hr->is_young(), "should not already be young");
 188   assert(hr->get_next_young_region() == NULL, "cause it should!");
 189 
 190   hr->set_next_young_region(_head);
 191   _head = hr;
 192 
 193   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 194   ++_length;
 195 }
 196 
 197 void YoungList::add_survivor_region(HeapRegion* hr) {
 198   assert(hr->is_survivor(), "should be flagged as survivor region");
 199   assert(hr->get_next_young_region() == NULL, "cause it should!");
 200 
 201   hr->set_next_young_region(_survivor_head);
 202   if (_survivor_head == NULL) {
 203     _survivor_tail = hr;
 204   }
 205   _survivor_head = hr;
 206   ++_survivor_length;
 207 }
 208 
 209 void YoungList::empty_list(HeapRegion* list) {
 210   while (list != NULL) {
 211     HeapRegion* next = list->get_next_young_region();
 212     list->set_next_young_region(NULL);
 213     list->uninstall_surv_rate_group();
 214     list->set_not_young();
 215     list = next;
 216   }
 217 }
 218 
 219 void YoungList::empty_list() {
 220   assert(check_list_well_formed(), "young list should be well formed");
 221 
 222   empty_list(_head);
 223   _head = NULL;
 224   _length = 0;
 225 
 226   empty_list(_survivor_head);
 227   _survivor_head = NULL;
 228   _survivor_tail = NULL;
 229   _survivor_length = 0;
 230 
 231   _last_sampled_rs_lengths = 0;
 232 
 233   assert(check_list_empty(false), "just making sure...");
 234 }
 235 
 236 bool YoungList::check_list_well_formed() {
 237   bool ret = true;
 238 
 239   uint length = 0;
 240   HeapRegion* curr = _head;
 241   HeapRegion* last = NULL;
 242   while (curr != NULL) {
 243     if (!curr->is_young()) {
 244       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 245                              "incorrectly tagged (y: %d, surv: %d)",
 246                              curr->bottom(), curr->end(),
 247                              curr->is_young(), curr->is_survivor());
 248       ret = false;
 249     }
 250     ++length;
 251     last = curr;
 252     curr = curr->get_next_young_region();
 253   }
 254   ret = ret && (length == _length);
 255 
 256   if (!ret) {
 257     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 258     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 259                            length, _length);
 260   }
 261 
 262   return ret;
 263 }
 264 
 265 bool YoungList::check_list_empty(bool check_sample) {
 266   bool ret = true;
 267 
 268   if (_length != 0) {
 269     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 270                   _length);
 271     ret = false;
 272   }
 273   if (check_sample && _last_sampled_rs_lengths != 0) {
 274     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 275     ret = false;
 276   }
 277   if (_head != NULL) {
 278     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 279     ret = false;
 280   }
 281   if (!ret) {
 282     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 283   }
 284 
 285   return ret;
 286 }
 287 
 288 void
 289 YoungList::rs_length_sampling_init() {
 290   _sampled_rs_lengths = 0;
 291   _curr               = _head;
 292 }
 293 
 294 bool
 295 YoungList::rs_length_sampling_more() {
 296   return _curr != NULL;
 297 }
 298 
 299 void
 300 YoungList::rs_length_sampling_next() {
 301   assert( _curr != NULL, "invariant" );
 302   size_t rs_length = _curr->rem_set()->occupied();
 303 
 304   _sampled_rs_lengths += rs_length;
 305 
 306   // The current region may not yet have been added to the
 307   // incremental collection set (it gets added when it is
 308   // retired as the current allocation region).
 309   if (_curr->in_collection_set()) {
 310     // Update the collection set policy information for this region
 311     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 312   }
 313 
 314   _curr = _curr->get_next_young_region();
 315   if (_curr == NULL) {
 316     _last_sampled_rs_lengths = _sampled_rs_lengths;
 317     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 318   }
 319 }
 320 
 321 void
 322 YoungList::reset_auxilary_lists() {
 323   guarantee( is_empty(), "young list should be empty" );
 324   assert(check_list_well_formed(), "young list should be well formed");
 325 
 326   // Add survivor regions to SurvRateGroup.
 327   _g1h->g1_policy()->note_start_adding_survivor_regions();
 328   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 329 
 330   int young_index_in_cset = 0;
 331   for (HeapRegion* curr = _survivor_head;
 332        curr != NULL;
 333        curr = curr->get_next_young_region()) {
 334     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 335 
 336     // The region is a non-empty survivor so let's add it to
 337     // the incremental collection set for the next evacuation
 338     // pause.
 339     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 340     young_index_in_cset += 1;
 341   }
 342   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 343   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 344 
 345   _head   = _survivor_head;
 346   _length = _survivor_length;
 347   if (_survivor_head != NULL) {
 348     assert(_survivor_tail != NULL, "cause it shouldn't be");
 349     assert(_survivor_length > 0, "invariant");
 350     _survivor_tail->set_next_young_region(NULL);
 351   }
 352 
 353   // Don't clear the survivor list handles until the start of
 354   // the next evacuation pause - we need it in order to re-tag
 355   // the survivor regions from this evacuation pause as 'young'
 356   // at the start of the next.
 357 
 358   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 359 
 360   assert(check_list_well_formed(), "young list should be well formed");
 361 }
 362 
 363 void YoungList::print() {
 364   HeapRegion* lists[] = {_head,   _survivor_head};
 365   const char* names[] = {"YOUNG", "SURVIVOR"};
 366 
 367   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 368     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 369     HeapRegion *curr = lists[list];
 370     if (curr == NULL)
 371       gclog_or_tty->print_cr("  empty");
 372     while (curr != NULL) {
 373       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 374                              HR_FORMAT_PARAMS(curr),
 375                              curr->prev_top_at_mark_start(),
 376                              curr->next_top_at_mark_start(),
 377                              curr->age_in_surv_rate_group_cond());
 378       curr = curr->get_next_young_region();
 379     }
 380   }
 381 
 382   gclog_or_tty->print_cr("");
 383 }
 384 
 385 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 386 {
 387   // Claim the right to put the region on the dirty cards region list
 388   // by installing a self pointer.
 389   HeapRegion* next = hr->get_next_dirty_cards_region();
 390   if (next == NULL) {
 391     HeapRegion* res = (HeapRegion*)
 392       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 393                           NULL);
 394     if (res == NULL) {
 395       HeapRegion* head;
 396       do {
 397         // Put the region to the dirty cards region list.
 398         head = _dirty_cards_region_list;
 399         next = (HeapRegion*)
 400           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 401         if (next == head) {
 402           assert(hr->get_next_dirty_cards_region() == hr,
 403                  "hr->get_next_dirty_cards_region() != hr");
 404           if (next == NULL) {
 405             // The last region in the list points to itself.
 406             hr->set_next_dirty_cards_region(hr);
 407           } else {
 408             hr->set_next_dirty_cards_region(next);
 409           }
 410         }
 411       } while (next != head);
 412     }
 413   }
 414 }
 415 
 416 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 417 {
 418   HeapRegion* head;
 419   HeapRegion* hr;
 420   do {
 421     head = _dirty_cards_region_list;
 422     if (head == NULL) {
 423       return NULL;
 424     }
 425     HeapRegion* new_head = head->get_next_dirty_cards_region();
 426     if (head == new_head) {
 427       // The last region.
 428       new_head = NULL;
 429     }
 430     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 431                                           head);
 432   } while (hr != head);
 433   assert(hr != NULL, "invariant");
 434   hr->set_next_dirty_cards_region(NULL);
 435   return hr;
 436 }
 437 
 438 void G1CollectedHeap::stop_conc_gc_threads() {
 439   _cg1r->stop();
 440   _cmThread->stop();
 441 }
 442 
 443 #ifdef ASSERT
 444 // A region is added to the collection set as it is retired
 445 // so an address p can point to a region which will be in the
 446 // collection set but has not yet been retired.  This method
 447 // therefore is only accurate during a GC pause after all
 448 // regions have been retired.  It is used for debugging
 449 // to check if an nmethod has references to objects that can
 450 // be move during a partial collection.  Though it can be
 451 // inaccurate, it is sufficient for G1 because the conservative
 452 // implementation of is_scavengable() for G1 will indicate that
 453 // all nmethods must be scanned during a partial collection.
 454 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 455   HeapRegion* hr = heap_region_containing(p);
 456   return hr != NULL && hr->in_collection_set();
 457 }
 458 #endif
 459 
 460 // Returns true if the reference points to an object that
 461 // can move in an incremental collecction.
 462 bool G1CollectedHeap::is_scavengable(const void* p) {
 463   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 464   G1CollectorPolicy* g1p = g1h->g1_policy();
 465   HeapRegion* hr = heap_region_containing(p);
 466   if (hr == NULL) {
 467      // null
 468      assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
 469      return false;
 470   } else {
 471     return !hr->isHumongous();
 472   }
 473 }
 474 
 475 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 476   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 477   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
 478 
 479   // Count the dirty cards at the start.
 480   CountNonCleanMemRegionClosure count1(this);
 481   ct_bs->mod_card_iterate(&count1);
 482   int orig_count = count1.n();
 483 
 484   // First clear the logged cards.
 485   ClearLoggedCardTableEntryClosure clear;
 486   dcqs.set_closure(&clear);
 487   dcqs.apply_closure_to_all_completed_buffers();
 488   dcqs.iterate_closure_all_threads(false);
 489   clear.print_histo();
 490 
 491   // Now ensure that there's no dirty cards.
 492   CountNonCleanMemRegionClosure count2(this);
 493   ct_bs->mod_card_iterate(&count2);
 494   if (count2.n() != 0) {
 495     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 496                            count2.n(), orig_count);
 497   }
 498   guarantee(count2.n() == 0, "Card table should be clean.");
 499 
 500   RedirtyLoggedCardTableEntryClosure redirty;
 501   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 502   dcqs.apply_closure_to_all_completed_buffers();
 503   dcqs.iterate_closure_all_threads(false);
 504   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 505                          clear.calls(), orig_count);
 506   guarantee(redirty.calls() == clear.calls(),
 507             "Or else mechanism is broken.");
 508 
 509   CountNonCleanMemRegionClosure count3(this);
 510   ct_bs->mod_card_iterate(&count3);
 511   if (count3.n() != orig_count) {
 512     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 513                            orig_count, count3.n());
 514     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 515   }
 516 
 517   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 518 }
 519 
 520 // Private class members.
 521 
 522 G1CollectedHeap* G1CollectedHeap::_g1h;
 523 
 524 // Private methods.
 525 
 526 HeapRegion*
 527 G1CollectedHeap::new_region_try_secondary_free_list() {
 528   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 529   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 530     if (!_secondary_free_list.is_empty()) {
 531       if (G1ConcRegionFreeingVerbose) {
 532         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 533                                "secondary_free_list has %u entries",
 534                                _secondary_free_list.length());
 535       }
 536       // It looks as if there are free regions available on the
 537       // secondary_free_list. Let's move them to the free_list and try
 538       // again to allocate from it.
 539       append_secondary_free_list();
 540 
 541       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 542              "empty we should have moved at least one entry to the free_list");
 543       HeapRegion* res = _free_list.remove_head();
 544       if (G1ConcRegionFreeingVerbose) {
 545         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 546                                "allocated "HR_FORMAT" from secondary_free_list",
 547                                HR_FORMAT_PARAMS(res));
 548       }
 549       return res;
 550     }
 551 
 552     // Wait here until we get notifed either when (a) there are no
 553     // more free regions coming or (b) some regions have been moved on
 554     // the secondary_free_list.
 555     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 556   }
 557 
 558   if (G1ConcRegionFreeingVerbose) {
 559     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 560                            "could not allocate from secondary_free_list");
 561   }
 562   return NULL;
 563 }
 564 
 565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 566   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 567          "the only time we use this to allocate a humongous region is "
 568          "when we are allocating a single humongous region");
 569 
 570   HeapRegion* res;
 571   if (G1StressConcRegionFreeing) {
 572     if (!_secondary_free_list.is_empty()) {
 573       if (G1ConcRegionFreeingVerbose) {
 574         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 575                                "forced to look at the secondary_free_list");
 576       }
 577       res = new_region_try_secondary_free_list();
 578       if (res != NULL) {
 579         return res;
 580       }
 581     }
 582   }
 583   res = _free_list.remove_head_or_null();
 584   if (res == NULL) {
 585     if (G1ConcRegionFreeingVerbose) {
 586       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 587                              "res == NULL, trying the secondary_free_list");
 588     }
 589     res = new_region_try_secondary_free_list();
 590   }
 591   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 592     // Currently, only attempts to allocate GC alloc regions set
 593     // do_expand to true. So, we should only reach here during a
 594     // safepoint. If this assumption changes we might have to
 595     // reconsider the use of _expand_heap_after_alloc_failure.
 596     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 597 
 598     ergo_verbose1(ErgoHeapSizing,
 599                   "attempt heap expansion",
 600                   ergo_format_reason("region allocation request failed")
 601                   ergo_format_byte("allocation request"),
 602                   word_size * HeapWordSize);
 603     if (expand(word_size * HeapWordSize)) {
 604       // Given that expand() succeeded in expanding the heap, and we
 605       // always expand the heap by an amount aligned to the heap
 606       // region size, the free list should in theory not be empty. So
 607       // it would probably be OK to use remove_head(). But the extra
 608       // check for NULL is unlikely to be a performance issue here (we
 609       // just expanded the heap!) so let's just be conservative and
 610       // use remove_head_or_null().
 611       res = _free_list.remove_head_or_null();
 612     } else {
 613       _expand_heap_after_alloc_failure = false;
 614     }
 615   }
 616   return res;
 617 }
 618 
 619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 620                                                         size_t word_size) {
 621   assert(isHumongous(word_size), "word_size should be humongous");
 622   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 623 
 624   uint first = G1_NULL_HRS_INDEX;
 625   if (num_regions == 1) {
 626     // Only one region to allocate, no need to go through the slower
 627     // path. The caller will attempt the expasion if this fails, so
 628     // let's not try to expand here too.
 629     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 630     if (hr != NULL) {
 631       first = hr->hrs_index();
 632     } else {
 633       first = G1_NULL_HRS_INDEX;
 634     }
 635   } else {
 636     // We can't allocate humongous regions while cleanupComplete() is
 637     // running, since some of the regions we find to be empty might not
 638     // yet be added to the free list and it is not straightforward to
 639     // know which list they are on so that we can remove them. Note
 640     // that we only need to do this if we need to allocate more than
 641     // one region to satisfy the current humongous allocation
 642     // request. If we are only allocating one region we use the common
 643     // region allocation code (see above).
 644     wait_while_free_regions_coming();
 645     append_secondary_free_list_if_not_empty_with_lock();
 646 
 647     if (free_regions() >= num_regions) {
 648       first = _hrs.find_contiguous(num_regions);
 649       if (first != G1_NULL_HRS_INDEX) {
 650         for (uint i = first; i < first + num_regions; ++i) {
 651           HeapRegion* hr = region_at(i);
 652           assert(hr->is_empty(), "sanity");
 653           assert(is_on_master_free_list(hr), "sanity");
 654           hr->set_pending_removal(true);
 655         }
 656         _free_list.remove_all_pending(num_regions);
 657       }
 658     }
 659   }
 660   return first;
 661 }
 662 
 663 HeapWord*
 664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 665                                                            uint num_regions,
 666                                                            size_t word_size) {
 667   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 668   assert(isHumongous(word_size), "word_size should be humongous");
 669   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 670 
 671   // Index of last region in the series + 1.
 672   uint last = first + num_regions;
 673 
 674   // We need to initialize the region(s) we just discovered. This is
 675   // a bit tricky given that it can happen concurrently with
 676   // refinement threads refining cards on these regions and
 677   // potentially wanting to refine the BOT as they are scanning
 678   // those cards (this can happen shortly after a cleanup; see CR
 679   // 6991377). So we have to set up the region(s) carefully and in
 680   // a specific order.
 681 
 682   // The word size sum of all the regions we will allocate.
 683   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 684   assert(word_size <= word_size_sum, "sanity");
 685 
 686   // This will be the "starts humongous" region.
 687   HeapRegion* first_hr = region_at(first);
 688   // The header of the new object will be placed at the bottom of
 689   // the first region.
 690   HeapWord* new_obj = first_hr->bottom();
 691   // This will be the new end of the first region in the series that
 692   // should also match the end of the last region in the seriers.
 693   HeapWord* new_end = new_obj + word_size_sum;
 694   // This will be the new top of the first region that will reflect
 695   // this allocation.
 696   HeapWord* new_top = new_obj + word_size;
 697 
 698   // First, we need to zero the header of the space that we will be
 699   // allocating. When we update top further down, some refinement
 700   // threads might try to scan the region. By zeroing the header we
 701   // ensure that any thread that will try to scan the region will
 702   // come across the zero klass word and bail out.
 703   //
 704   // NOTE: It would not have been correct to have used
 705   // CollectedHeap::fill_with_object() and make the space look like
 706   // an int array. The thread that is doing the allocation will
 707   // later update the object header to a potentially different array
 708   // type and, for a very short period of time, the klass and length
 709   // fields will be inconsistent. This could cause a refinement
 710   // thread to calculate the object size incorrectly.
 711   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 712 
 713   // We will set up the first region as "starts humongous". This
 714   // will also update the BOT covering all the regions to reflect
 715   // that there is a single object that starts at the bottom of the
 716   // first region.
 717   first_hr->set_startsHumongous(new_top, new_end);
 718 
 719   // Then, if there are any, we will set up the "continues
 720   // humongous" regions.
 721   HeapRegion* hr = NULL;
 722   for (uint i = first + 1; i < last; ++i) {
 723     hr = region_at(i);
 724     hr->set_continuesHumongous(first_hr);
 725   }
 726   // If we have "continues humongous" regions (hr != NULL), then the
 727   // end of the last one should match new_end.
 728   assert(hr == NULL || hr->end() == new_end, "sanity");
 729 
 730   // Up to this point no concurrent thread would have been able to
 731   // do any scanning on any region in this series. All the top
 732   // fields still point to bottom, so the intersection between
 733   // [bottom,top] and [card_start,card_end] will be empty. Before we
 734   // update the top fields, we'll do a storestore to make sure that
 735   // no thread sees the update to top before the zeroing of the
 736   // object header and the BOT initialization.
 737   OrderAccess::storestore();
 738 
 739   // Now that the BOT and the object header have been initialized,
 740   // we can update top of the "starts humongous" region.
 741   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 742          "new_top should be in this region");
 743   first_hr->set_top(new_top);
 744   if (_hr_printer.is_active()) {
 745     HeapWord* bottom = first_hr->bottom();
 746     HeapWord* end = first_hr->orig_end();
 747     if ((first + 1) == last) {
 748       // the series has a single humongous region
 749       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 750     } else {
 751       // the series has more than one humongous regions
 752       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 753     }
 754   }
 755 
 756   // Now, we will update the top fields of the "continues humongous"
 757   // regions. The reason we need to do this is that, otherwise,
 758   // these regions would look empty and this will confuse parts of
 759   // G1. For example, the code that looks for a consecutive number
 760   // of empty regions will consider them empty and try to
 761   // re-allocate them. We can extend is_empty() to also include
 762   // !continuesHumongous(), but it is easier to just update the top
 763   // fields here. The way we set top for all regions (i.e., top ==
 764   // end for all regions but the last one, top == new_top for the
 765   // last one) is actually used when we will free up the humongous
 766   // region in free_humongous_region().
 767   hr = NULL;
 768   for (uint i = first + 1; i < last; ++i) {
 769     hr = region_at(i);
 770     if ((i + 1) == last) {
 771       // last continues humongous region
 772       assert(hr->bottom() < new_top && new_top <= hr->end(),
 773              "new_top should fall on this region");
 774       hr->set_top(new_top);
 775       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 776     } else {
 777       // not last one
 778       assert(new_top > hr->end(), "new_top should be above this region");
 779       hr->set_top(hr->end());
 780       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 781     }
 782   }
 783   // If we have continues humongous regions (hr != NULL), then the
 784   // end of the last one should match new_end and its top should
 785   // match new_top.
 786   assert(hr == NULL ||
 787          (hr->end() == new_end && hr->top() == new_top), "sanity");
 788 
 789   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 790   _summary_bytes_used += first_hr->used();
 791   _humongous_set.add(first_hr);
 792 
 793   return new_obj;
 794 }
 795 
 796 // If could fit into free regions w/o expansion, try.
 797 // Otherwise, if can expand, do so.
 798 // Otherwise, if using ex regions might help, try with ex given back.
 799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 800   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 801 
 802   verify_region_sets_optional();
 803 
 804   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 805   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 806   uint x_num = expansion_regions();
 807   uint fs = _hrs.free_suffix();
 808   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 809   if (first == G1_NULL_HRS_INDEX) {
 810     // The only thing we can do now is attempt expansion.
 811     if (fs + x_num >= num_regions) {
 812       // If the number of regions we're trying to allocate for this
 813       // object is at most the number of regions in the free suffix,
 814       // then the call to humongous_obj_allocate_find_first() above
 815       // should have succeeded and we wouldn't be here.
 816       //
 817       // We should only be trying to expand when the free suffix is
 818       // not sufficient for the object _and_ we have some expansion
 819       // room available.
 820       assert(num_regions > fs, "earlier allocation should have succeeded");
 821 
 822       ergo_verbose1(ErgoHeapSizing,
 823                     "attempt heap expansion",
 824                     ergo_format_reason("humongous allocation request failed")
 825                     ergo_format_byte("allocation request"),
 826                     word_size * HeapWordSize);
 827       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 828         // Even though the heap was expanded, it might not have
 829         // reached the desired size. So, we cannot assume that the
 830         // allocation will succeed.
 831         first = humongous_obj_allocate_find_first(num_regions, word_size);
 832       }
 833     }
 834   }
 835 
 836   HeapWord* result = NULL;
 837   if (first != G1_NULL_HRS_INDEX) {
 838     result =
 839       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 840     assert(result != NULL, "it should always return a valid result");
 841 
 842     // A successful humongous object allocation changes the used space
 843     // information of the old generation so we need to recalculate the
 844     // sizes and update the jstat counters here.
 845     g1mm()->update_sizes();
 846   }
 847 
 848   verify_region_sets_optional();
 849 
 850   return result;
 851 }
 852 
 853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 854   assert_heap_not_locked_and_not_at_safepoint();
 855   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 856 
 857   unsigned int dummy_gc_count_before;
 858   int dummy_gclocker_retry_count = 0;
 859   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 860 }
 861 
 862 HeapWord*
 863 G1CollectedHeap::mem_allocate(size_t word_size,
 864                               bool*  gc_overhead_limit_was_exceeded) {
 865   assert_heap_not_locked_and_not_at_safepoint();
 866 
 867   // Loop until the allocation is satisified, or unsatisfied after GC.
 868   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 869     unsigned int gc_count_before;
 870 
 871     HeapWord* result = NULL;
 872     if (!isHumongous(word_size)) {
 873       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 874     } else {
 875       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 876     }
 877     if (result != NULL) {
 878       return result;
 879     }
 880 
 881     // Create the garbage collection operation...
 882     VM_G1CollectForAllocation op(gc_count_before, word_size);
 883     // ...and get the VM thread to execute it.
 884     VMThread::execute(&op);
 885 
 886     if (op.prologue_succeeded() && op.pause_succeeded()) {
 887       // If the operation was successful we'll return the result even
 888       // if it is NULL. If the allocation attempt failed immediately
 889       // after a Full GC, it's unlikely we'll be able to allocate now.
 890       HeapWord* result = op.result();
 891       if (result != NULL && !isHumongous(word_size)) {
 892         // Allocations that take place on VM operations do not do any
 893         // card dirtying and we have to do it here. We only have to do
 894         // this for non-humongous allocations, though.
 895         dirty_young_block(result, word_size);
 896       }
 897       return result;
 898     } else {
 899       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 900         return NULL;
 901       }
 902       assert(op.result() == NULL,
 903              "the result should be NULL if the VM op did not succeed");
 904     }
 905 
 906     // Give a warning if we seem to be looping forever.
 907     if ((QueuedAllocationWarningCount > 0) &&
 908         (try_count % QueuedAllocationWarningCount == 0)) {
 909       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 910     }
 911   }
 912 
 913   ShouldNotReachHere();
 914   return NULL;
 915 }
 916 
 917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 918                                            unsigned int *gc_count_before_ret,
 919                                            int* gclocker_retry_count_ret) {
 920   // Make sure you read the note in attempt_allocation_humongous().
 921 
 922   assert_heap_not_locked_and_not_at_safepoint();
 923   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 924          "be called for humongous allocation requests");
 925 
 926   // We should only get here after the first-level allocation attempt
 927   // (attempt_allocation()) failed to allocate.
 928 
 929   // We will loop until a) we manage to successfully perform the
 930   // allocation or b) we successfully schedule a collection which
 931   // fails to perform the allocation. b) is the only case when we'll
 932   // return NULL.
 933   HeapWord* result = NULL;
 934   for (int try_count = 1; /* we'll return */; try_count += 1) {
 935     bool should_try_gc;
 936     unsigned int gc_count_before;
 937 
 938     {
 939       MutexLockerEx x(Heap_lock);
 940 
 941       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 942                                                       false /* bot_updates */);
 943       if (result != NULL) {
 944         return result;
 945       }
 946 
 947       // If we reach here, attempt_allocation_locked() above failed to
 948       // allocate a new region. So the mutator alloc region should be NULL.
 949       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 950 
 951       if (GC_locker::is_active_and_needs_gc()) {
 952         if (g1_policy()->can_expand_young_list()) {
 953           // No need for an ergo verbose message here,
 954           // can_expand_young_list() does this when it returns true.
 955           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 956                                                       false /* bot_updates */);
 957           if (result != NULL) {
 958             return result;
 959           }
 960         }
 961         should_try_gc = false;
 962       } else {
 963         // The GCLocker may not be active but the GCLocker initiated
 964         // GC may not yet have been performed (GCLocker::needs_gc()
 965         // returns true). In this case we do not try this GC and
 966         // wait until the GCLocker initiated GC is performed, and
 967         // then retry the allocation.
 968         if (GC_locker::needs_gc()) {
 969           should_try_gc = false;
 970         } else {
 971           // Read the GC count while still holding the Heap_lock.
 972           gc_count_before = total_collections();
 973           should_try_gc = true;
 974         }
 975       }
 976     }
 977 
 978     if (should_try_gc) {
 979       bool succeeded;
 980       result = do_collection_pause(word_size, gc_count_before, &succeeded);
 981       if (result != NULL) {
 982         assert(succeeded, "only way to get back a non-NULL result");
 983         return result;
 984       }
 985 
 986       if (succeeded) {
 987         // If we get here we successfully scheduled a collection which
 988         // failed to allocate. No point in trying to allocate
 989         // further. We'll just return NULL.
 990         MutexLockerEx x(Heap_lock);
 991         *gc_count_before_ret = total_collections();
 992         return NULL;
 993       }
 994     } else {
 995       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 996         MutexLockerEx x(Heap_lock);
 997         *gc_count_before_ret = total_collections();
 998         return NULL;
 999       }
1000       // The GCLocker is either active or the GCLocker initiated
1001       // GC has not yet been performed. Stall until it is and
1002       // then retry the allocation.
1003       GC_locker::stall_until_clear();
1004       (*gclocker_retry_count_ret) += 1;
1005     }
1006 
1007     // We can reach here if we were unsuccessul in scheduling a
1008     // collection (because another thread beat us to it) or if we were
1009     // stalled due to the GC locker. In either can we should retry the
1010     // allocation attempt in case another thread successfully
1011     // performed a collection and reclaimed enough space. We do the
1012     // first attempt (without holding the Heap_lock) here and the
1013     // follow-on attempt will be at the start of the next loop
1014     // iteration (after taking the Heap_lock).
1015     result = _mutator_alloc_region.attempt_allocation(word_size,
1016                                                       false /* bot_updates */);
1017     if (result != NULL) {
1018       return result;
1019     }
1020 
1021     // Give a warning if we seem to be looping forever.
1022     if ((QueuedAllocationWarningCount > 0) &&
1023         (try_count % QueuedAllocationWarningCount == 0)) {
1024       warning("G1CollectedHeap::attempt_allocation_slow() "
1025               "retries %d times", try_count);
1026     }
1027   }
1028 
1029   ShouldNotReachHere();
1030   return NULL;
1031 }
1032 
1033 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1034                                           unsigned int * gc_count_before_ret,
1035                                           int* gclocker_retry_count_ret) {
1036   // The structure of this method has a lot of similarities to
1037   // attempt_allocation_slow(). The reason these two were not merged
1038   // into a single one is that such a method would require several "if
1039   // allocation is not humongous do this, otherwise do that"
1040   // conditional paths which would obscure its flow. In fact, an early
1041   // version of this code did use a unified method which was harder to
1042   // follow and, as a result, it had subtle bugs that were hard to
1043   // track down. So keeping these two methods separate allows each to
1044   // be more readable. It will be good to keep these two in sync as
1045   // much as possible.
1046 
1047   assert_heap_not_locked_and_not_at_safepoint();
1048   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1049          "should only be called for humongous allocations");
1050 
1051   // Humongous objects can exhaust the heap quickly, so we should check if we
1052   // need to start a marking cycle at each humongous object allocation. We do
1053   // the check before we do the actual allocation. The reason for doing it
1054   // before the allocation is that we avoid having to keep track of the newly
1055   // allocated memory while we do a GC.
1056   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1057                                            word_size)) {
1058     collect(GCCause::_g1_humongous_allocation);
1059   }
1060 
1061   // We will loop until a) we manage to successfully perform the
1062   // allocation or b) we successfully schedule a collection which
1063   // fails to perform the allocation. b) is the only case when we'll
1064   // return NULL.
1065   HeapWord* result = NULL;
1066   for (int try_count = 1; /* we'll return */; try_count += 1) {
1067     bool should_try_gc;
1068     unsigned int gc_count_before;
1069 
1070     {
1071       MutexLockerEx x(Heap_lock);
1072 
1073       // Given that humongous objects are not allocated in young
1074       // regions, we'll first try to do the allocation without doing a
1075       // collection hoping that there's enough space in the heap.
1076       result = humongous_obj_allocate(word_size);
1077       if (result != NULL) {
1078         return result;
1079       }
1080 
1081       if (GC_locker::is_active_and_needs_gc()) {
1082         should_try_gc = false;
1083       } else {
1084          // The GCLocker may not be active but the GCLocker initiated
1085         // GC may not yet have been performed (GCLocker::needs_gc()
1086         // returns true). In this case we do not try this GC and
1087         // wait until the GCLocker initiated GC is performed, and
1088         // then retry the allocation.
1089         if (GC_locker::needs_gc()) {
1090           should_try_gc = false;
1091         } else {
1092           // Read the GC count while still holding the Heap_lock.
1093           gc_count_before = total_collections();
1094           should_try_gc = true;
1095         }
1096       }
1097     }
1098 
1099     if (should_try_gc) {
1100       // If we failed to allocate the humongous object, we should try to
1101       // do a collection pause (if we're allowed) in case it reclaims
1102       // enough space for the allocation to succeed after the pause.
1103 
1104       bool succeeded;
1105       result = do_collection_pause(word_size, gc_count_before, &succeeded);
1106       if (result != NULL) {
1107         assert(succeeded, "only way to get back a non-NULL result");
1108         return result;
1109       }
1110 
1111       if (succeeded) {
1112         // If we get here we successfully scheduled a collection which
1113         // failed to allocate. No point in trying to allocate
1114         // further. We'll just return NULL.
1115         MutexLockerEx x(Heap_lock);
1116         *gc_count_before_ret = total_collections();
1117         return NULL;
1118       }
1119     } else {
1120       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1121         MutexLockerEx x(Heap_lock);
1122         *gc_count_before_ret = total_collections();
1123         return NULL;
1124       }
1125       // The GCLocker is either active or the GCLocker initiated
1126       // GC has not yet been performed. Stall until it is and
1127       // then retry the allocation.
1128       GC_locker::stall_until_clear();
1129       (*gclocker_retry_count_ret) += 1;
1130     }
1131 
1132     // We can reach here if we were unsuccessul in scheduling a
1133     // collection (because another thread beat us to it) or if we were
1134     // stalled due to the GC locker. In either can we should retry the
1135     // allocation attempt in case another thread successfully
1136     // performed a collection and reclaimed enough space.  Give a
1137     // warning if we seem to be looping forever.
1138 
1139     if ((QueuedAllocationWarningCount > 0) &&
1140         (try_count % QueuedAllocationWarningCount == 0)) {
1141       warning("G1CollectedHeap::attempt_allocation_humongous() "
1142               "retries %d times", try_count);
1143     }
1144   }
1145 
1146   ShouldNotReachHere();
1147   return NULL;
1148 }
1149 
1150 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1151                                        bool expect_null_mutator_alloc_region) {
1152   assert_at_safepoint(true /* should_be_vm_thread */);
1153   assert(_mutator_alloc_region.get() == NULL ||
1154                                              !expect_null_mutator_alloc_region,
1155          "the current alloc region was unexpectedly found to be non-NULL");
1156 
1157   if (!isHumongous(word_size)) {
1158     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1159                                                       false /* bot_updates */);
1160   } else {
1161     HeapWord* result = humongous_obj_allocate(word_size);
1162     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1163       g1_policy()->set_initiate_conc_mark_if_possible();
1164     }
1165     return result;
1166   }
1167 
1168   ShouldNotReachHere();
1169 }
1170 
1171 class PostMCRemSetClearClosure: public HeapRegionClosure {
1172   G1CollectedHeap* _g1h;
1173   ModRefBarrierSet* _mr_bs;
1174 public:
1175   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1176     _g1h(g1h), _mr_bs(mr_bs) {}
1177 
1178   bool doHeapRegion(HeapRegion* r) {
1179     if (r->continuesHumongous()) {
1180       // We'll assert that the strong code root list is empty
1181       assert(r->strong_code_root_list()->is_empty(), "sanity");
1182       return false;
1183     }
1184     _g1h->reset_gc_time_stamps(r);
1185     HeapRegionRemSet* hrrs = r->rem_set();
1186     if (hrrs != NULL) hrrs->clear();
1187     // You might think here that we could clear just the cards
1188     // corresponding to the used region.  But no: if we leave a dirty card
1189     // in a region we might allocate into, then it would prevent that card
1190     // from being enqueued, and cause it to be missed.
1191     // Re: the performance cost: we shouldn't be doing full GC anyway!
1192     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1193 
1194     // We'll also clear the strong code root list for this region
1195     r->strong_code_root_list()->clear();
1196 
1197     return false;
1198   }
1199 };
1200 
1201 void G1CollectedHeap::clear_rsets_post_compaction() {
1202   PostMCRemSetClearClosure rs_clear(this, mr_bs());
1203   heap_region_iterate(&rs_clear);
1204 }
1205 
1206 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1207   G1CollectedHeap*   _g1h;
1208   UpdateRSOopClosure _cl;
1209   int                _worker_i;
1210 public:
1211   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1212     _cl(g1->g1_rem_set(), worker_i),
1213     _worker_i(worker_i),
1214     _g1h(g1)
1215   { }
1216 
1217   bool doHeapRegion(HeapRegion* r) {
1218     if (!r->continuesHumongous()) {
1219       _cl.set_from(r);
1220       r->oop_iterate(&_cl);
1221     }
1222     return false;
1223   }
1224 };
1225 
1226 class ParRebuildRSTask: public AbstractGangTask {
1227   G1CollectedHeap* _g1;
1228 public:
1229   ParRebuildRSTask(G1CollectedHeap* g1)
1230     : AbstractGangTask("ParRebuildRSTask"),
1231       _g1(g1)
1232   { }
1233 
1234   void work(uint worker_id) {
1235     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1236     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1237                                           _g1->workers()->active_workers(),
1238                                          HeapRegion::RebuildRSClaimValue);
1239   }
1240 };
1241 
1242 class PostCompactionPrinterClosure: public HeapRegionClosure {
1243 private:
1244   G1HRPrinter* _hr_printer;
1245 public:
1246   bool doHeapRegion(HeapRegion* hr) {
1247     assert(!hr->is_young(), "not expecting to find young regions");
1248     // We only generate output for non-empty regions.
1249     if (!hr->is_empty()) {
1250       if (!hr->isHumongous()) {
1251         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1252       } else if (hr->startsHumongous()) {
1253         if (hr->region_num() == 1) {
1254           // single humongous region
1255           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1256         } else {
1257           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1258         }
1259       } else {
1260         assert(hr->continuesHumongous(), "only way to get here");
1261         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1262       }
1263     }
1264     return false;
1265   }
1266 
1267   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1268     : _hr_printer(hr_printer) { }
1269 };
1270 
1271 void G1CollectedHeap::print_hrs_post_compaction() {
1272   PostCompactionPrinterClosure cl(hr_printer());
1273   heap_region_iterate(&cl);
1274 }
1275 
1276 bool G1CollectedHeap::do_collection(bool explicit_gc,
1277                                     bool clear_all_soft_refs,
1278                                     size_t word_size) {
1279   assert_at_safepoint(true /* should_be_vm_thread */);
1280 
1281   if (GC_locker::check_active_before_gc()) {
1282     return false;
1283   }
1284 
1285   SvcGCMarker sgcm(SvcGCMarker::FULL);
1286   ResourceMark rm;
1287 
1288   print_heap_before_gc();
1289 
1290   size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1291 
1292   HRSPhaseSetter x(HRSPhaseFullGC);
1293   verify_region_sets_optional();
1294 
1295   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1296                            collector_policy()->should_clear_all_soft_refs();
1297 
1298   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1299 
1300   {
1301     IsGCActiveMark x;
1302 
1303     // Timing
1304     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1305     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1306     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1307 
1308     {
1309       TraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, gclog_or_tty);
1310       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1311       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1312 
1313       double start = os::elapsedTime();
1314       g1_policy()->record_full_collection_start();
1315 
1316       // Note: When we have a more flexible GC logging framework that
1317       // allows us to add optional attributes to a GC log record we
1318       // could consider timing and reporting how long we wait in the
1319       // following two methods.
1320       wait_while_free_regions_coming();
1321       // If we start the compaction before the CM threads finish
1322       // scanning the root regions we might trip them over as we'll
1323       // be moving objects / updating references. So let's wait until
1324       // they are done. By telling them to abort, they should complete
1325       // early.
1326       _cm->root_regions()->abort();
1327       _cm->root_regions()->wait_until_scan_finished();
1328       append_secondary_free_list_if_not_empty_with_lock();
1329 
1330       gc_prologue(true);
1331       increment_total_collections(true /* full gc */);
1332       increment_old_marking_cycles_started();
1333 
1334       assert(used() == recalculate_used(), "Should be equal");
1335 
1336       verify_before_gc();
1337 
1338       pre_full_gc_dump();
1339 
1340       COMPILER2_PRESENT(DerivedPointerTable::clear());
1341 
1342       // Disable discovery and empty the discovered lists
1343       // for the CM ref processor.
1344       ref_processor_cm()->disable_discovery();
1345       ref_processor_cm()->abandon_partial_discovery();
1346       ref_processor_cm()->verify_no_references_recorded();
1347 
1348       // Abandon current iterations of concurrent marking and concurrent
1349       // refinement, if any are in progress. We have to do this before
1350       // wait_until_scan_finished() below.
1351       concurrent_mark()->abort();
1352 
1353       // Make sure we'll choose a new allocation region afterwards.
1354       release_mutator_alloc_region();
1355       abandon_gc_alloc_regions();
1356       g1_rem_set()->cleanupHRRS();
1357 
1358       // We should call this after we retire any currently active alloc
1359       // regions so that all the ALLOC / RETIRE events are generated
1360       // before the start GC event.
1361       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1362 
1363       // We may have added regions to the current incremental collection
1364       // set between the last GC or pause and now. We need to clear the
1365       // incremental collection set and then start rebuilding it afresh
1366       // after this full GC.
1367       abandon_collection_set(g1_policy()->inc_cset_head());
1368       g1_policy()->clear_incremental_cset();
1369       g1_policy()->stop_incremental_cset_building();
1370 
1371       tear_down_region_sets(false /* free_list_only */);
1372       g1_policy()->set_gcs_are_young(true);
1373 
1374       // See the comments in g1CollectedHeap.hpp and
1375       // G1CollectedHeap::ref_processing_init() about
1376       // how reference processing currently works in G1.
1377 
1378       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1379       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1380 
1381       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1382       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1383 
1384       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1385       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1386 
1387       // Do collection work
1388       {
1389         HandleMark hm;  // Discard invalid handles created during gc
1390         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1391       }
1392 
1393       assert(free_regions() == 0, "we should not have added any free regions");
1394       rebuild_region_sets(false /* free_list_only */);
1395 
1396       // Enqueue any discovered reference objects that have
1397       // not been removed from the discovered lists.
1398       ref_processor_stw()->enqueue_discovered_references();
1399 
1400       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1401 
1402       MemoryService::track_memory_usage();
1403 
1404       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1405       ref_processor_stw()->verify_no_references_recorded();
1406 
1407       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1408       ClassLoaderDataGraph::purge();
1409       MetaspaceAux::verify_metrics();
1410 
1411       // Note: since we've just done a full GC, concurrent
1412       // marking is no longer active. Therefore we need not
1413       // re-enable reference discovery for the CM ref processor.
1414       // That will be done at the start of the next marking cycle.
1415       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1416       ref_processor_cm()->verify_no_references_recorded();
1417 
1418       reset_gc_time_stamp();
1419       // Since everything potentially moved, we will clear all remembered
1420       // sets, and clear all cards.  Later we will rebuild remebered
1421       // sets. We will also reset the GC time stamps of the regions.
1422       clear_rsets_post_compaction();
1423       check_gc_time_stamps();
1424 
1425       // Resize the heap if necessary.
1426       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1427 
1428       if (_hr_printer.is_active()) {
1429         // We should do this after we potentially resize the heap so
1430         // that all the COMMIT / UNCOMMIT events are generated before
1431         // the end GC event.
1432 
1433         print_hrs_post_compaction();
1434         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1435       }
1436 
1437       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1438       if (hot_card_cache->use_cache()) {
1439         hot_card_cache->reset_card_counts();
1440         hot_card_cache->reset_hot_cache();
1441       }
1442 
1443       // Rebuild remembered sets of all regions.
1444       if (G1CollectedHeap::use_parallel_gc_threads()) {
1445         uint n_workers =
1446           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1447                                                   workers()->active_workers(),
1448                                                   Threads::number_of_non_daemon_threads());
1449         assert(UseDynamicNumberOfGCThreads ||
1450                n_workers == workers()->total_workers(),
1451                "If not dynamic should be using all the  workers");
1452         workers()->set_active_workers(n_workers);
1453         // Set parallel threads in the heap (_n_par_threads) only
1454         // before a parallel phase and always reset it to 0 after
1455         // the phase so that the number of parallel threads does
1456         // no get carried forward to a serial phase where there
1457         // may be code that is "possibly_parallel".
1458         set_par_threads(n_workers);
1459 
1460         ParRebuildRSTask rebuild_rs_task(this);
1461         assert(check_heap_region_claim_values(
1462                HeapRegion::InitialClaimValue), "sanity check");
1463         assert(UseDynamicNumberOfGCThreads ||
1464                workers()->active_workers() == workers()->total_workers(),
1465                "Unless dynamic should use total workers");
1466         // Use the most recent number of  active workers
1467         assert(workers()->active_workers() > 0,
1468                "Active workers not properly set");
1469         set_par_threads(workers()->active_workers());
1470         workers()->run_task(&rebuild_rs_task);
1471         set_par_threads(0);
1472         assert(check_heap_region_claim_values(
1473                HeapRegion::RebuildRSClaimValue), "sanity check");
1474         reset_heap_region_claim_values();
1475       } else {
1476         RebuildRSOutOfRegionClosure rebuild_rs(this);
1477         heap_region_iterate(&rebuild_rs);
1478       }
1479 
1480       // Rebuild the strong code root lists for each region
1481       rebuild_strong_code_roots();
1482 
1483       if (true) { // FIXME
1484         MetaspaceGC::compute_new_size();
1485       }
1486 
1487 #ifdef TRACESPINNING
1488       ParallelTaskTerminator::print_termination_counts();
1489 #endif
1490 
1491       // Discard all rset updates
1492       JavaThread::dirty_card_queue_set().abandon_logs();
1493       assert(!G1DeferredRSUpdate
1494              || (G1DeferredRSUpdate &&
1495                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1496 
1497       _young_list->reset_sampled_info();
1498       // At this point there should be no regions in the
1499       // entire heap tagged as young.
1500       assert(check_young_list_empty(true /* check_heap */),
1501              "young list should be empty at this point");
1502 
1503       // Update the number of full collections that have been completed.
1504       increment_old_marking_cycles_completed(false /* concurrent */);
1505 
1506       _hrs.verify_optional();
1507       verify_region_sets_optional();
1508 
1509       verify_after_gc();
1510 
1511       // Start a new incremental collection set for the next pause
1512       assert(g1_policy()->collection_set() == NULL, "must be");
1513       g1_policy()->start_incremental_cset_building();
1514 
1515       // Clear the _cset_fast_test bitmap in anticipation of adding
1516       // regions to the incremental collection set for the next
1517       // evacuation pause.
1518       clear_cset_fast_test();
1519 
1520       init_mutator_alloc_region();
1521 
1522       double end = os::elapsedTime();
1523       g1_policy()->record_full_collection_end();
1524 
1525       if (G1Log::fine()) {
1526         g1_policy()->print_heap_transition();
1527       }
1528 
1529       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1530       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1531       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1532       // before any GC notifications are raised.
1533       g1mm()->update_sizes();
1534 
1535       gc_epilogue(true);
1536     }
1537 
1538     if (G1Log::finer()) {
1539       g1_policy()->print_detailed_heap_transition(true /* full */);
1540     }
1541 
1542     print_heap_after_gc();
1543 
1544     post_full_gc_dump();
1545   }
1546 
1547   return true;
1548 }
1549 
1550 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1551   // do_collection() will return whether it succeeded in performing
1552   // the GC. Currently, there is no facility on the
1553   // do_full_collection() API to notify the caller than the collection
1554   // did not succeed (e.g., because it was locked out by the GC
1555   // locker). So, right now, we'll ignore the return value.
1556   bool dummy = do_collection(true,                /* explicit_gc */
1557                              clear_all_soft_refs,
1558                              0                    /* word_size */);
1559 }
1560 
1561 // This code is mostly copied from TenuredGeneration.
1562 void
1563 G1CollectedHeap::
1564 resize_if_necessary_after_full_collection(size_t word_size) {
1565   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1566 
1567   // Include the current allocation, if any, and bytes that will be
1568   // pre-allocated to support collections, as "used".
1569   const size_t used_after_gc = used();
1570   const size_t capacity_after_gc = capacity();
1571   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1572 
1573   // This is enforced in arguments.cpp.
1574   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1575          "otherwise the code below doesn't make sense");
1576 
1577   // We don't have floating point command-line arguments
1578   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1579   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1580   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1581   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1582 
1583   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1584   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1585 
1586   // We have to be careful here as these two calculations can overflow
1587   // 32-bit size_t's.
1588   double used_after_gc_d = (double) used_after_gc;
1589   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1590   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1591 
1592   // Let's make sure that they are both under the max heap size, which
1593   // by default will make them fit into a size_t.
1594   double desired_capacity_upper_bound = (double) max_heap_size;
1595   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1596                                     desired_capacity_upper_bound);
1597   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1598                                     desired_capacity_upper_bound);
1599 
1600   // We can now safely turn them into size_t's.
1601   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1602   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1603 
1604   // This assert only makes sense here, before we adjust them
1605   // with respect to the min and max heap size.
1606   assert(minimum_desired_capacity <= maximum_desired_capacity,
1607          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1608                  "maximum_desired_capacity = "SIZE_FORMAT,
1609                  minimum_desired_capacity, maximum_desired_capacity));
1610 
1611   // Should not be greater than the heap max size. No need to adjust
1612   // it with respect to the heap min size as it's a lower bound (i.e.,
1613   // we'll try to make the capacity larger than it, not smaller).
1614   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1615   // Should not be less than the heap min size. No need to adjust it
1616   // with respect to the heap max size as it's an upper bound (i.e.,
1617   // we'll try to make the capacity smaller than it, not greater).
1618   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1619 
1620   if (capacity_after_gc < minimum_desired_capacity) {
1621     // Don't expand unless it's significant
1622     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1623     ergo_verbose4(ErgoHeapSizing,
1624                   "attempt heap expansion",
1625                   ergo_format_reason("capacity lower than "
1626                                      "min desired capacity after Full GC")
1627                   ergo_format_byte("capacity")
1628                   ergo_format_byte("occupancy")
1629                   ergo_format_byte_perc("min desired capacity"),
1630                   capacity_after_gc, used_after_gc,
1631                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1632     expand(expand_bytes);
1633 
1634     // No expansion, now see if we want to shrink
1635   } else if (capacity_after_gc > maximum_desired_capacity) {
1636     // Capacity too large, compute shrinking size
1637     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1638     ergo_verbose4(ErgoHeapSizing,
1639                   "attempt heap shrinking",
1640                   ergo_format_reason("capacity higher than "
1641                                      "max desired capacity after Full GC")
1642                   ergo_format_byte("capacity")
1643                   ergo_format_byte("occupancy")
1644                   ergo_format_byte_perc("max desired capacity"),
1645                   capacity_after_gc, used_after_gc,
1646                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1647     shrink(shrink_bytes);
1648   }
1649 }
1650 
1651 
1652 HeapWord*
1653 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1654                                            bool* succeeded) {
1655   assert_at_safepoint(true /* should_be_vm_thread */);
1656 
1657   *succeeded = true;
1658   // Let's attempt the allocation first.
1659   HeapWord* result =
1660     attempt_allocation_at_safepoint(word_size,
1661                                  false /* expect_null_mutator_alloc_region */);
1662   if (result != NULL) {
1663     assert(*succeeded, "sanity");
1664     return result;
1665   }
1666 
1667   // In a G1 heap, we're supposed to keep allocation from failing by
1668   // incremental pauses.  Therefore, at least for now, we'll favor
1669   // expansion over collection.  (This might change in the future if we can
1670   // do something smarter than full collection to satisfy a failed alloc.)
1671   result = expand_and_allocate(word_size);
1672   if (result != NULL) {
1673     assert(*succeeded, "sanity");
1674     return result;
1675   }
1676 
1677   // Expansion didn't work, we'll try to do a Full GC.
1678   bool gc_succeeded = do_collection(false, /* explicit_gc */
1679                                     false, /* clear_all_soft_refs */
1680                                     word_size);
1681   if (!gc_succeeded) {
1682     *succeeded = false;
1683     return NULL;
1684   }
1685 
1686   // Retry the allocation
1687   result = attempt_allocation_at_safepoint(word_size,
1688                                   true /* expect_null_mutator_alloc_region */);
1689   if (result != NULL) {
1690     assert(*succeeded, "sanity");
1691     return result;
1692   }
1693 
1694   // Then, try a Full GC that will collect all soft references.
1695   gc_succeeded = do_collection(false, /* explicit_gc */
1696                                true,  /* clear_all_soft_refs */
1697                                word_size);
1698   if (!gc_succeeded) {
1699     *succeeded = false;
1700     return NULL;
1701   }
1702 
1703   // Retry the allocation once more
1704   result = attempt_allocation_at_safepoint(word_size,
1705                                   true /* expect_null_mutator_alloc_region */);
1706   if (result != NULL) {
1707     assert(*succeeded, "sanity");
1708     return result;
1709   }
1710 
1711   assert(!collector_policy()->should_clear_all_soft_refs(),
1712          "Flag should have been handled and cleared prior to this point");
1713 
1714   // What else?  We might try synchronous finalization later.  If the total
1715   // space available is large enough for the allocation, then a more
1716   // complete compaction phase than we've tried so far might be
1717   // appropriate.
1718   assert(*succeeded, "sanity");
1719   return NULL;
1720 }
1721 
1722 // Attempting to expand the heap sufficiently
1723 // to support an allocation of the given "word_size".  If
1724 // successful, perform the allocation and return the address of the
1725 // allocated block, or else "NULL".
1726 
1727 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1728   assert_at_safepoint(true /* should_be_vm_thread */);
1729 
1730   verify_region_sets_optional();
1731 
1732   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1733   ergo_verbose1(ErgoHeapSizing,
1734                 "attempt heap expansion",
1735                 ergo_format_reason("allocation request failed")
1736                 ergo_format_byte("allocation request"),
1737                 word_size * HeapWordSize);
1738   if (expand(expand_bytes)) {
1739     _hrs.verify_optional();
1740     verify_region_sets_optional();
1741     return attempt_allocation_at_safepoint(word_size,
1742                                  false /* expect_null_mutator_alloc_region */);
1743   }
1744   return NULL;
1745 }
1746 
1747 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1748                                              HeapWord* new_end) {
1749   assert(old_end != new_end, "don't call this otherwise");
1750   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1751 
1752   // Update the committed mem region.
1753   _g1_committed.set_end(new_end);
1754   // Tell the card table about the update.
1755   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1756   // Tell the BOT about the update.
1757   _bot_shared->resize(_g1_committed.word_size());
1758   // Tell the hot card cache about the update
1759   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1760 }
1761 
1762 bool G1CollectedHeap::expand(size_t expand_bytes) {
1763   size_t old_mem_size = _g1_storage.committed_size();
1764   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1765   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1766                                        HeapRegion::GrainBytes);
1767   ergo_verbose2(ErgoHeapSizing,
1768                 "expand the heap",
1769                 ergo_format_byte("requested expansion amount")
1770                 ergo_format_byte("attempted expansion amount"),
1771                 expand_bytes, aligned_expand_bytes);
1772 
1773   // First commit the memory.
1774   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1775   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1776   if (successful) {
1777     // Then propagate this update to the necessary data structures.
1778     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1779     update_committed_space(old_end, new_end);
1780 
1781     FreeRegionList expansion_list("Local Expansion List");
1782     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1783     assert(mr.start() == old_end, "post-condition");
1784     // mr might be a smaller region than what was requested if
1785     // expand_by() was unable to allocate the HeapRegion instances
1786     assert(mr.end() <= new_end, "post-condition");
1787 
1788     size_t actual_expand_bytes = mr.byte_size();
1789     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1790     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1791            "post-condition");
1792     if (actual_expand_bytes < aligned_expand_bytes) {
1793       // We could not expand _hrs to the desired size. In this case we
1794       // need to shrink the committed space accordingly.
1795       assert(mr.end() < new_end, "invariant");
1796 
1797       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1798       // First uncommit the memory.
1799       _g1_storage.shrink_by(diff_bytes);
1800       // Then propagate this update to the necessary data structures.
1801       update_committed_space(new_end, mr.end());
1802     }
1803     _free_list.add_as_tail(&expansion_list);
1804 
1805     if (_hr_printer.is_active()) {
1806       HeapWord* curr = mr.start();
1807       while (curr < mr.end()) {
1808         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1809         _hr_printer.commit(curr, curr_end);
1810         curr = curr_end;
1811       }
1812       assert(curr == mr.end(), "post-condition");
1813     }
1814     g1_policy()->record_new_heap_size(n_regions());
1815   } else {
1816     ergo_verbose0(ErgoHeapSizing,
1817                   "did not expand the heap",
1818                   ergo_format_reason("heap expansion operation failed"));
1819     // The expansion of the virtual storage space was unsuccessful.
1820     // Let's see if it was because we ran out of swap.
1821     if (G1ExitOnExpansionFailure &&
1822         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1823       // We had head room...
1824       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1825     }
1826   }
1827   return successful;
1828 }
1829 
1830 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1831   size_t old_mem_size = _g1_storage.committed_size();
1832   size_t aligned_shrink_bytes =
1833     ReservedSpace::page_align_size_down(shrink_bytes);
1834   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1835                                          HeapRegion::GrainBytes);
1836   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1837 
1838   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1839   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1840   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1841 
1842   ergo_verbose3(ErgoHeapSizing,
1843                 "shrink the heap",
1844                 ergo_format_byte("requested shrinking amount")
1845                 ergo_format_byte("aligned shrinking amount")
1846                 ergo_format_byte("attempted shrinking amount"),
1847                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1848   if (num_regions_removed > 0) {
1849     _g1_storage.shrink_by(shrunk_bytes);
1850     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1851 
1852     if (_hr_printer.is_active()) {
1853       HeapWord* curr = old_end;
1854       while (curr > new_end) {
1855         HeapWord* curr_end = curr;
1856         curr -= HeapRegion::GrainWords;
1857         _hr_printer.uncommit(curr, curr_end);
1858       }
1859     }
1860 
1861     _expansion_regions += num_regions_removed;
1862     update_committed_space(old_end, new_end);
1863     HeapRegionRemSet::shrink_heap(n_regions());
1864     g1_policy()->record_new_heap_size(n_regions());
1865   } else {
1866     ergo_verbose0(ErgoHeapSizing,
1867                   "did not shrink the heap",
1868                   ergo_format_reason("heap shrinking operation failed"));
1869   }
1870 }
1871 
1872 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1873   verify_region_sets_optional();
1874 
1875   // We should only reach here at the end of a Full GC which means we
1876   // should not not be holding to any GC alloc regions. The method
1877   // below will make sure of that and do any remaining clean up.
1878   abandon_gc_alloc_regions();
1879 
1880   // Instead of tearing down / rebuilding the free lists here, we
1881   // could instead use the remove_all_pending() method on free_list to
1882   // remove only the ones that we need to remove.
1883   tear_down_region_sets(true /* free_list_only */);
1884   shrink_helper(shrink_bytes);
1885   rebuild_region_sets(true /* free_list_only */);
1886 
1887   _hrs.verify_optional();
1888   verify_region_sets_optional();
1889 }
1890 
1891 // Public methods.
1892 
1893 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1894 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1895 #endif // _MSC_VER
1896 
1897 
1898 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1899   SharedHeap(policy_),
1900   _g1_policy(policy_),
1901   _dirty_card_queue_set(false),
1902   _into_cset_dirty_card_queue_set(false),
1903   _is_alive_closure_cm(this),
1904   _is_alive_closure_stw(this),
1905   _ref_processor_cm(NULL),
1906   _ref_processor_stw(NULL),
1907   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1908   _bot_shared(NULL),
1909   _evac_failure_scan_stack(NULL) ,
1910   _mark_in_progress(false),
1911   _cg1r(NULL), _summary_bytes_used(0),
1912   _g1mm(NULL),
1913   _refine_cte_cl(NULL),
1914   _full_collection(false),
1915   _free_list("Master Free List"),
1916   _secondary_free_list("Secondary Free List"),
1917   _old_set("Old Set"),
1918   _humongous_set("Master Humongous Set"),
1919   _free_regions_coming(false),
1920   _young_list(new YoungList(this)),
1921   _gc_time_stamp(0),
1922   _retained_old_gc_alloc_region(NULL),
1923   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1924   _old_plab_stats(OldPLABSize, PLABWeight),
1925   _expand_heap_after_alloc_failure(true),
1926   _surviving_young_words(NULL),
1927   _old_marking_cycles_started(0),
1928   _old_marking_cycles_completed(0),
1929   _in_cset_fast_test(NULL),
1930   _in_cset_fast_test_base(NULL),
1931   _dirty_cards_region_list(NULL),
1932   _worker_cset_start_region(NULL),
1933   _worker_cset_start_region_time_stamp(NULL) {
1934   _g1h = this; // To catch bugs.
1935   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1936     vm_exit_during_initialization("Failed necessary allocation.");
1937   }
1938 
1939   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1940 
1941   int n_queues = MAX2((int)ParallelGCThreads, 1);
1942   _task_queues = new RefToScanQueueSet(n_queues);
1943 
1944   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1945   assert(n_rem_sets > 0, "Invariant.");
1946 
1947   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1948   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1949 
1950   for (int i = 0; i < n_queues; i++) {
1951     RefToScanQueue* q = new RefToScanQueue();
1952     q->initialize();
1953     _task_queues->register_queue(i, q);
1954   }
1955 
1956   clear_cset_start_regions();
1957 
1958   // Initialize the G1EvacuationFailureALot counters and flags.
1959   NOT_PRODUCT(reset_evacuation_should_fail();)
1960 
1961   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1962 }
1963 
1964 jint G1CollectedHeap::initialize() {
1965   CollectedHeap::pre_initialize();
1966   os::enable_vtime();
1967 
1968   G1Log::init();
1969 
1970   // Necessary to satisfy locking discipline assertions.
1971 
1972   MutexLocker x(Heap_lock);
1973 
1974   // We have to initialize the printer before committing the heap, as
1975   // it will be used then.
1976   _hr_printer.set_active(G1PrintHeapRegions);
1977 
1978   // While there are no constraints in the GC code that HeapWordSize
1979   // be any particular value, there are multiple other areas in the
1980   // system which believe this to be true (e.g. oop->object_size in some
1981   // cases incorrectly returns the size in wordSize units rather than
1982   // HeapWordSize).
1983   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1984 
1985   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1986   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1987 
1988   // Ensure that the sizes are properly aligned.
1989   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1990   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1991 
1992   _cg1r = new ConcurrentG1Refine(this);
1993 
1994   // Reserve the maximum.
1995 
1996   // When compressed oops are enabled, the preferred heap base
1997   // is calculated by subtracting the requested size from the
1998   // 32Gb boundary and using the result as the base address for
1999   // heap reservation. If the requested size is not aligned to
2000   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2001   // into the ReservedHeapSpace constructor) then the actual
2002   // base of the reserved heap may end up differing from the
2003   // address that was requested (i.e. the preferred heap base).
2004   // If this happens then we could end up using a non-optimal
2005   // compressed oops mode.
2006 
2007   // Since max_byte_size is aligned to the size of a heap region (checked
2008   // above).
2009   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2010 
2011   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2012                                                  HeapRegion::GrainBytes);
2013 
2014   // It is important to do this in a way such that concurrent readers can't
2015   // temporarily think somethings in the heap.  (I've actually seen this
2016   // happen in asserts: DLD.)
2017   _reserved.set_word_size(0);
2018   _reserved.set_start((HeapWord*)heap_rs.base());
2019   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2020 
2021   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2022 
2023   // Create the gen rem set (and barrier set) for the entire reserved region.
2024   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2025   set_barrier_set(rem_set()->bs());
2026   if (barrier_set()->is_a(BarrierSet::ModRef)) {
2027     _mr_bs = (ModRefBarrierSet*)_barrier_set;
2028   } else {
2029     vm_exit_during_initialization("G1 requires a mod ref bs.");
2030     return JNI_ENOMEM;
2031   }
2032 
2033   // Also create a G1 rem set.
2034   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2035     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2036   } else {
2037     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2038     return JNI_ENOMEM;
2039   }
2040 
2041   // Carve out the G1 part of the heap.
2042 
2043   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2044   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2045                            g1_rs.size()/HeapWordSize);
2046 
2047   _g1_storage.initialize(g1_rs, 0);
2048   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2049   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2050                   (HeapWord*) _g1_reserved.end(),
2051                   _expansion_regions);
2052 
2053   // Do later initialization work for concurrent refinement.
2054   _cg1r->init();
2055 
2056   // 6843694 - ensure that the maximum region index can fit
2057   // in the remembered set structures.
2058   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2059   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2060 
2061   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2062   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2063   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2064             "too many cards per region");
2065 
2066   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2067 
2068   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2069                                              heap_word_size(init_byte_size));
2070 
2071   _g1h = this;
2072 
2073   _in_cset_fast_test_length = max_regions();
2074   _in_cset_fast_test_base =
2075                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2076 
2077   // We're biasing _in_cset_fast_test to avoid subtracting the
2078   // beginning of the heap every time we want to index; basically
2079   // it's the same with what we do with the card table.
2080   _in_cset_fast_test = _in_cset_fast_test_base -
2081                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2082 
2083   // Clear the _cset_fast_test bitmap in anticipation of adding
2084   // regions to the incremental collection set for the first
2085   // evacuation pause.
2086   clear_cset_fast_test();
2087 
2088   // Create the ConcurrentMark data structure and thread.
2089   // (Must do this late, so that "max_regions" is defined.)
2090   _cm = new ConcurrentMark(this, heap_rs);
2091   if (_cm == NULL || !_cm->completed_initialization()) {
2092     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2093     return JNI_ENOMEM;
2094   }
2095   _cmThread = _cm->cmThread();
2096 
2097   // Initialize the from_card cache structure of HeapRegionRemSet.
2098   HeapRegionRemSet::init_heap(max_regions());
2099 
2100   // Now expand into the initial heap size.
2101   if (!expand(init_byte_size)) {
2102     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2103     return JNI_ENOMEM;
2104   }
2105 
2106   // Perform any initialization actions delegated to the policy.
2107   g1_policy()->init();
2108 
2109   _refine_cte_cl =
2110     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2111                                     g1_rem_set(),
2112                                     concurrent_g1_refine());
2113   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2114 
2115   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2116                                                SATB_Q_FL_lock,
2117                                                G1SATBProcessCompletedThreshold,
2118                                                Shared_SATB_Q_lock);
2119 
2120   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2121                                                 DirtyCardQ_FL_lock,
2122                                                 concurrent_g1_refine()->yellow_zone(),
2123                                                 concurrent_g1_refine()->red_zone(),
2124                                                 Shared_DirtyCardQ_lock);
2125 
2126   if (G1DeferredRSUpdate) {
2127     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2128                                       DirtyCardQ_FL_lock,
2129                                       -1, // never trigger processing
2130                                       -1, // no limit on length
2131                                       Shared_DirtyCardQ_lock,
2132                                       &JavaThread::dirty_card_queue_set());
2133   }
2134 
2135   // Initialize the card queue set used to hold cards containing
2136   // references into the collection set.
2137   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2138                                              DirtyCardQ_FL_lock,
2139                                              -1, // never trigger processing
2140                                              -1, // no limit on length
2141                                              Shared_DirtyCardQ_lock,
2142                                              &JavaThread::dirty_card_queue_set());
2143 
2144   // In case we're keeping closure specialization stats, initialize those
2145   // counts and that mechanism.
2146   SpecializationStats::clear();
2147 
2148   // Here we allocate the dummy full region that is required by the
2149   // G1AllocRegion class. If we don't pass an address in the reserved
2150   // space here, lots of asserts fire.
2151 
2152   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2153                                              _g1_reserved.start());
2154   // We'll re-use the same region whether the alloc region will
2155   // require BOT updates or not and, if it doesn't, then a non-young
2156   // region will complain that it cannot support allocations without
2157   // BOT updates. So we'll tag the dummy region as young to avoid that.
2158   dummy_region->set_young();
2159   // Make sure it's full.
2160   dummy_region->set_top(dummy_region->end());
2161   G1AllocRegion::setup(this, dummy_region);
2162 
2163   init_mutator_alloc_region();
2164 
2165   // Do create of the monitoring and management support so that
2166   // values in the heap have been properly initialized.
2167   _g1mm = new G1MonitoringSupport(this);
2168 
2169   return JNI_OK;
2170 }
2171 
2172 void G1CollectedHeap::ref_processing_init() {
2173   // Reference processing in G1 currently works as follows:
2174   //
2175   // * There are two reference processor instances. One is
2176   //   used to record and process discovered references
2177   //   during concurrent marking; the other is used to
2178   //   record and process references during STW pauses
2179   //   (both full and incremental).
2180   // * Both ref processors need to 'span' the entire heap as
2181   //   the regions in the collection set may be dotted around.
2182   //
2183   // * For the concurrent marking ref processor:
2184   //   * Reference discovery is enabled at initial marking.
2185   //   * Reference discovery is disabled and the discovered
2186   //     references processed etc during remarking.
2187   //   * Reference discovery is MT (see below).
2188   //   * Reference discovery requires a barrier (see below).
2189   //   * Reference processing may or may not be MT
2190   //     (depending on the value of ParallelRefProcEnabled
2191   //     and ParallelGCThreads).
2192   //   * A full GC disables reference discovery by the CM
2193   //     ref processor and abandons any entries on it's
2194   //     discovered lists.
2195   //
2196   // * For the STW processor:
2197   //   * Non MT discovery is enabled at the start of a full GC.
2198   //   * Processing and enqueueing during a full GC is non-MT.
2199   //   * During a full GC, references are processed after marking.
2200   //
2201   //   * Discovery (may or may not be MT) is enabled at the start
2202   //     of an incremental evacuation pause.
2203   //   * References are processed near the end of a STW evacuation pause.
2204   //   * For both types of GC:
2205   //     * Discovery is atomic - i.e. not concurrent.
2206   //     * Reference discovery will not need a barrier.
2207 
2208   SharedHeap::ref_processing_init();
2209   MemRegion mr = reserved_region();
2210 
2211   // Concurrent Mark ref processor
2212   _ref_processor_cm =
2213     new ReferenceProcessor(mr,    // span
2214                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2215                                 // mt processing
2216                            (int) ParallelGCThreads,
2217                                 // degree of mt processing
2218                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2219                                 // mt discovery
2220                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2221                                 // degree of mt discovery
2222                            false,
2223                                 // Reference discovery is not atomic
2224                            &_is_alive_closure_cm,
2225                                 // is alive closure
2226                                 // (for efficiency/performance)
2227                            true);
2228                                 // Setting next fields of discovered
2229                                 // lists requires a barrier.
2230 
2231   // STW ref processor
2232   _ref_processor_stw =
2233     new ReferenceProcessor(mr,    // span
2234                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2235                                 // mt processing
2236                            MAX2((int)ParallelGCThreads, 1),
2237                                 // degree of mt processing
2238                            (ParallelGCThreads > 1),
2239                                 // mt discovery
2240                            MAX2((int)ParallelGCThreads, 1),
2241                                 // degree of mt discovery
2242                            true,
2243                                 // Reference discovery is atomic
2244                            &_is_alive_closure_stw,
2245                                 // is alive closure
2246                                 // (for efficiency/performance)
2247                            false);
2248                                 // Setting next fields of discovered
2249                                 // lists requires a barrier.
2250 }
2251 
2252 size_t G1CollectedHeap::capacity() const {
2253   return _g1_committed.byte_size();
2254 }
2255 
2256 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2257   assert(!hr->continuesHumongous(), "pre-condition");
2258   hr->reset_gc_time_stamp();
2259   if (hr->startsHumongous()) {
2260     uint first_index = hr->hrs_index() + 1;
2261     uint last_index = hr->last_hc_index();
2262     for (uint i = first_index; i < last_index; i += 1) {
2263       HeapRegion* chr = region_at(i);
2264       assert(chr->continuesHumongous(), "sanity");
2265       chr->reset_gc_time_stamp();
2266     }
2267   }
2268 }
2269 
2270 #ifndef PRODUCT
2271 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2272 private:
2273   unsigned _gc_time_stamp;
2274   bool _failures;
2275 
2276 public:
2277   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2278     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2279 
2280   virtual bool doHeapRegion(HeapRegion* hr) {
2281     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2282     if (_gc_time_stamp != region_gc_time_stamp) {
2283       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2284                              "expected %d", HR_FORMAT_PARAMS(hr),
2285                              region_gc_time_stamp, _gc_time_stamp);
2286       _failures = true;
2287     }
2288     return false;
2289   }
2290 
2291   bool failures() { return _failures; }
2292 };
2293 
2294 void G1CollectedHeap::check_gc_time_stamps() {
2295   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2296   heap_region_iterate(&cl);
2297   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2298 }
2299 #endif // PRODUCT
2300 
2301 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2302                                                  DirtyCardQueue* into_cset_dcq,
2303                                                  bool concurrent,
2304                                                  int worker_i) {
2305   // Clean cards in the hot card cache
2306   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2307   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2308 
2309   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2310   int n_completed_buffers = 0;
2311   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2312     n_completed_buffers++;
2313   }
2314   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2315   dcqs.clear_n_completed_buffers();
2316   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2317 }
2318 
2319 
2320 // Computes the sum of the storage used by the various regions.
2321 
2322 size_t G1CollectedHeap::used() const {
2323   assert(Heap_lock->owner() != NULL,
2324          "Should be owned on this thread's behalf.");
2325   size_t result = _summary_bytes_used;
2326   // Read only once in case it is set to NULL concurrently
2327   HeapRegion* hr = _mutator_alloc_region.get();
2328   if (hr != NULL)
2329     result += hr->used();
2330   return result;
2331 }
2332 
2333 size_t G1CollectedHeap::used_unlocked() const {
2334   size_t result = _summary_bytes_used;
2335   return result;
2336 }
2337 
2338 class SumUsedClosure: public HeapRegionClosure {
2339   size_t _used;
2340 public:
2341   SumUsedClosure() : _used(0) {}
2342   bool doHeapRegion(HeapRegion* r) {
2343     if (!r->continuesHumongous()) {
2344       _used += r->used();
2345     }
2346     return false;
2347   }
2348   size_t result() { return _used; }
2349 };
2350 
2351 size_t G1CollectedHeap::recalculate_used() const {
2352   SumUsedClosure blk;
2353   heap_region_iterate(&blk);
2354   return blk.result();
2355 }
2356 
2357 size_t G1CollectedHeap::unsafe_max_alloc() {
2358   if (free_regions() > 0) return HeapRegion::GrainBytes;
2359   // otherwise, is there space in the current allocation region?
2360 
2361   // We need to store the current allocation region in a local variable
2362   // here. The problem is that this method doesn't take any locks and
2363   // there may be other threads which overwrite the current allocation
2364   // region field. attempt_allocation(), for example, sets it to NULL
2365   // and this can happen *after* the NULL check here but before the call
2366   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2367   // to be a problem in the optimized build, since the two loads of the
2368   // current allocation region field are optimized away.
2369   HeapRegion* hr = _mutator_alloc_region.get();
2370   if (hr == NULL) {
2371     return 0;
2372   }
2373   return hr->free();
2374 }
2375 
2376 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2377   switch (cause) {
2378     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2379     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2380     case GCCause::_g1_humongous_allocation: return true;
2381     default:                                return false;
2382   }
2383 }
2384 
2385 #ifndef PRODUCT
2386 void G1CollectedHeap::allocate_dummy_regions() {
2387   // Let's fill up most of the region
2388   size_t word_size = HeapRegion::GrainWords - 1024;
2389   // And as a result the region we'll allocate will be humongous.
2390   guarantee(isHumongous(word_size), "sanity");
2391 
2392   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2393     // Let's use the existing mechanism for the allocation
2394     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2395     if (dummy_obj != NULL) {
2396       MemRegion mr(dummy_obj, word_size);
2397       CollectedHeap::fill_with_object(mr);
2398     } else {
2399       // If we can't allocate once, we probably cannot allocate
2400       // again. Let's get out of the loop.
2401       break;
2402     }
2403   }
2404 }
2405 #endif // !PRODUCT
2406 
2407 void G1CollectedHeap::increment_old_marking_cycles_started() {
2408   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2409     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2410     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2411     _old_marking_cycles_started, _old_marking_cycles_completed));
2412 
2413   _old_marking_cycles_started++;
2414 }
2415 
2416 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2417   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2418 
2419   // We assume that if concurrent == true, then the caller is a
2420   // concurrent thread that was joined the Suspendible Thread
2421   // Set. If there's ever a cheap way to check this, we should add an
2422   // assert here.
2423 
2424   // Given that this method is called at the end of a Full GC or of a
2425   // concurrent cycle, and those can be nested (i.e., a Full GC can
2426   // interrupt a concurrent cycle), the number of full collections
2427   // completed should be either one (in the case where there was no
2428   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2429   // behind the number of full collections started.
2430 
2431   // This is the case for the inner caller, i.e. a Full GC.
2432   assert(concurrent ||
2433          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2434          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2435          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2436                  "is inconsistent with _old_marking_cycles_completed = %u",
2437                  _old_marking_cycles_started, _old_marking_cycles_completed));
2438 
2439   // This is the case for the outer caller, i.e. the concurrent cycle.
2440   assert(!concurrent ||
2441          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2442          err_msg("for outer caller (concurrent cycle): "
2443                  "_old_marking_cycles_started = %u "
2444                  "is inconsistent with _old_marking_cycles_completed = %u",
2445                  _old_marking_cycles_started, _old_marking_cycles_completed));
2446 
2447   _old_marking_cycles_completed += 1;
2448 
2449   // We need to clear the "in_progress" flag in the CM thread before
2450   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2451   // is set) so that if a waiter requests another System.gc() it doesn't
2452   // incorrectly see that a marking cyle is still in progress.
2453   if (concurrent) {
2454     _cmThread->clear_in_progress();
2455   }
2456 
2457   // This notify_all() will ensure that a thread that called
2458   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2459   // and it's waiting for a full GC to finish will be woken up. It is
2460   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2461   FullGCCount_lock->notify_all();
2462 }
2463 
2464 void G1CollectedHeap::collect(GCCause::Cause cause) {
2465   assert_heap_not_locked();
2466 
2467   unsigned int gc_count_before;
2468   unsigned int old_marking_count_before;
2469   bool retry_gc;
2470 
2471   do {
2472     retry_gc = false;
2473 
2474     {
2475       MutexLocker ml(Heap_lock);
2476 
2477       // Read the GC count while holding the Heap_lock
2478       gc_count_before = total_collections();
2479       old_marking_count_before = _old_marking_cycles_started;
2480     }
2481 
2482     if (should_do_concurrent_full_gc(cause)) {
2483       // Schedule an initial-mark evacuation pause that will start a
2484       // concurrent cycle. We're setting word_size to 0 which means that
2485       // we are not requesting a post-GC allocation.
2486       VM_G1IncCollectionPause op(gc_count_before,
2487                                  0,     /* word_size */
2488                                  true,  /* should_initiate_conc_mark */
2489                                  g1_policy()->max_pause_time_ms(),
2490                                  cause);
2491 
2492       VMThread::execute(&op);
2493       if (!op.pause_succeeded()) {
2494         if (old_marking_count_before == _old_marking_cycles_started) {
2495           retry_gc = op.should_retry_gc();
2496         } else {
2497           // A Full GC happened while we were trying to schedule the
2498           // initial-mark GC. No point in starting a new cycle given
2499           // that the whole heap was collected anyway.
2500         }
2501 
2502         if (retry_gc) {
2503           if (GC_locker::is_active_and_needs_gc()) {
2504             GC_locker::stall_until_clear();
2505           }
2506         }
2507       }
2508     } else {
2509       if (cause == GCCause::_gc_locker
2510           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2511 
2512         // Schedule a standard evacuation pause. We're setting word_size
2513         // to 0 which means that we are not requesting a post-GC allocation.
2514         VM_G1IncCollectionPause op(gc_count_before,
2515                                    0,     /* word_size */
2516                                    false, /* should_initiate_conc_mark */
2517                                    g1_policy()->max_pause_time_ms(),
2518                                    cause);
2519         VMThread::execute(&op);
2520       } else {
2521         // Schedule a Full GC.
2522         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2523         VMThread::execute(&op);
2524       }
2525     }
2526   } while (retry_gc);
2527 }
2528 
2529 bool G1CollectedHeap::is_in(const void* p) const {
2530   if (_g1_committed.contains(p)) {
2531     // Given that we know that p is in the committed space,
2532     // heap_region_containing_raw() should successfully
2533     // return the containing region.
2534     HeapRegion* hr = heap_region_containing_raw(p);
2535     return hr->is_in(p);
2536   } else {
2537     return false;
2538   }
2539 }
2540 
2541 // Iteration functions.
2542 
2543 // Iterates an OopClosure over all ref-containing fields of objects
2544 // within a HeapRegion.
2545 
2546 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2547   MemRegion _mr;
2548   ExtendedOopClosure* _cl;
2549 public:
2550   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2551     : _mr(mr), _cl(cl) {}
2552   bool doHeapRegion(HeapRegion* r) {
2553     if (!r->continuesHumongous()) {
2554       r->oop_iterate(_cl);
2555     }
2556     return false;
2557   }
2558 };
2559 
2560 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2561   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2562   heap_region_iterate(&blk);
2563 }
2564 
2565 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2566   IterateOopClosureRegionClosure blk(mr, cl);
2567   heap_region_iterate(&blk);
2568 }
2569 
2570 // Iterates an ObjectClosure over all objects within a HeapRegion.
2571 
2572 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2573   ObjectClosure* _cl;
2574 public:
2575   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2576   bool doHeapRegion(HeapRegion* r) {
2577     if (! r->continuesHumongous()) {
2578       r->object_iterate(_cl);
2579     }
2580     return false;
2581   }
2582 };
2583 
2584 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2585   IterateObjectClosureRegionClosure blk(cl);
2586   heap_region_iterate(&blk);
2587 }
2588 
2589 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2590   // FIXME: is this right?
2591   guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2592 }
2593 
2594 // Calls a SpaceClosure on a HeapRegion.
2595 
2596 class SpaceClosureRegionClosure: public HeapRegionClosure {
2597   SpaceClosure* _cl;
2598 public:
2599   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2600   bool doHeapRegion(HeapRegion* r) {
2601     _cl->do_space(r);
2602     return false;
2603   }
2604 };
2605 
2606 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2607   SpaceClosureRegionClosure blk(cl);
2608   heap_region_iterate(&blk);
2609 }
2610 
2611 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2612   _hrs.iterate(cl);
2613 }
2614 
2615 void
2616 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2617                                                  uint worker_id,
2618                                                  uint no_of_par_workers,
2619                                                  jint claim_value) {
2620   const uint regions = n_regions();
2621   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2622                              no_of_par_workers :
2623                              1);
2624   assert(UseDynamicNumberOfGCThreads ||
2625          no_of_par_workers == workers()->total_workers(),
2626          "Non dynamic should use fixed number of workers");
2627   // try to spread out the starting points of the workers
2628   const HeapRegion* start_hr =
2629                         start_region_for_worker(worker_id, no_of_par_workers);
2630   const uint start_index = start_hr->hrs_index();
2631 
2632   // each worker will actually look at all regions
2633   for (uint count = 0; count < regions; ++count) {
2634     const uint index = (start_index + count) % regions;
2635     assert(0 <= index && index < regions, "sanity");
2636     HeapRegion* r = region_at(index);
2637     // we'll ignore "continues humongous" regions (we'll process them
2638     // when we come across their corresponding "start humongous"
2639     // region) and regions already claimed
2640     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2641       continue;
2642     }
2643     // OK, try to claim it
2644     if (r->claimHeapRegion(claim_value)) {
2645       // success!
2646       assert(!r->continuesHumongous(), "sanity");
2647       if (r->startsHumongous()) {
2648         // If the region is "starts humongous" we'll iterate over its
2649         // "continues humongous" first; in fact we'll do them
2650         // first. The order is important. In on case, calling the
2651         // closure on the "starts humongous" region might de-allocate
2652         // and clear all its "continues humongous" regions and, as a
2653         // result, we might end up processing them twice. So, we'll do
2654         // them first (notice: most closures will ignore them anyway) and
2655         // then we'll do the "starts humongous" region.
2656         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2657           HeapRegion* chr = region_at(ch_index);
2658 
2659           // if the region has already been claimed or it's not
2660           // "continues humongous" we're done
2661           if (chr->claim_value() == claim_value ||
2662               !chr->continuesHumongous()) {
2663             break;
2664           }
2665 
2666           // Noone should have claimed it directly. We can given
2667           // that we claimed its "starts humongous" region.
2668           assert(chr->claim_value() != claim_value, "sanity");
2669           assert(chr->humongous_start_region() == r, "sanity");
2670 
2671           if (chr->claimHeapRegion(claim_value)) {
2672             // we should always be able to claim it; noone else should
2673             // be trying to claim this region
2674 
2675             bool res2 = cl->doHeapRegion(chr);
2676             assert(!res2, "Should not abort");
2677 
2678             // Right now, this holds (i.e., no closure that actually
2679             // does something with "continues humongous" regions
2680             // clears them). We might have to weaken it in the future,
2681             // but let's leave these two asserts here for extra safety.
2682             assert(chr->continuesHumongous(), "should still be the case");
2683             assert(chr->humongous_start_region() == r, "sanity");
2684           } else {
2685             guarantee(false, "we should not reach here");
2686           }
2687         }
2688       }
2689 
2690       assert(!r->continuesHumongous(), "sanity");
2691       bool res = cl->doHeapRegion(r);
2692       assert(!res, "Should not abort");
2693     }
2694   }
2695 }
2696 
2697 class ResetClaimValuesClosure: public HeapRegionClosure {
2698 public:
2699   bool doHeapRegion(HeapRegion* r) {
2700     r->set_claim_value(HeapRegion::InitialClaimValue);
2701     return false;
2702   }
2703 };
2704 
2705 void G1CollectedHeap::reset_heap_region_claim_values() {
2706   ResetClaimValuesClosure blk;
2707   heap_region_iterate(&blk);
2708 }
2709 
2710 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2711   ResetClaimValuesClosure blk;
2712   collection_set_iterate(&blk);
2713 }
2714 
2715 #ifdef ASSERT
2716 // This checks whether all regions in the heap have the correct claim
2717 // value. I also piggy-backed on this a check to ensure that the
2718 // humongous_start_region() information on "continues humongous"
2719 // regions is correct.
2720 
2721 class CheckClaimValuesClosure : public HeapRegionClosure {
2722 private:
2723   jint _claim_value;
2724   uint _failures;
2725   HeapRegion* _sh_region;
2726 
2727 public:
2728   CheckClaimValuesClosure(jint claim_value) :
2729     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2730   bool doHeapRegion(HeapRegion* r) {
2731     if (r->claim_value() != _claim_value) {
2732       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2733                              "claim value = %d, should be %d",
2734                              HR_FORMAT_PARAMS(r),
2735                              r->claim_value(), _claim_value);
2736       ++_failures;
2737     }
2738     if (!r->isHumongous()) {
2739       _sh_region = NULL;
2740     } else if (r->startsHumongous()) {
2741       _sh_region = r;
2742     } else if (r->continuesHumongous()) {
2743       if (r->humongous_start_region() != _sh_region) {
2744         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2745                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2746                                HR_FORMAT_PARAMS(r),
2747                                r->humongous_start_region(),
2748                                _sh_region);
2749         ++_failures;
2750       }
2751     }
2752     return false;
2753   }
2754   uint failures() { return _failures; }
2755 };
2756 
2757 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2758   CheckClaimValuesClosure cl(claim_value);
2759   heap_region_iterate(&cl);
2760   return cl.failures() == 0;
2761 }
2762 
2763 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2764 private:
2765   jint _claim_value;
2766   uint _failures;
2767 
2768 public:
2769   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2770     _claim_value(claim_value), _failures(0) { }
2771 
2772   uint failures() { return _failures; }
2773 
2774   bool doHeapRegion(HeapRegion* hr) {
2775     assert(hr->in_collection_set(), "how?");
2776     assert(!hr->isHumongous(), "H-region in CSet");
2777     if (hr->claim_value() != _claim_value) {
2778       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2779                              "claim value = %d, should be %d",
2780                              HR_FORMAT_PARAMS(hr),
2781                              hr->claim_value(), _claim_value);
2782       _failures += 1;
2783     }
2784     return false;
2785   }
2786 };
2787 
2788 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2789   CheckClaimValuesInCSetHRClosure cl(claim_value);
2790   collection_set_iterate(&cl);
2791   return cl.failures() == 0;
2792 }
2793 #endif // ASSERT
2794 
2795 // Clear the cached CSet starting regions and (more importantly)
2796 // the time stamps. Called when we reset the GC time stamp.
2797 void G1CollectedHeap::clear_cset_start_regions() {
2798   assert(_worker_cset_start_region != NULL, "sanity");
2799   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2800 
2801   int n_queues = MAX2((int)ParallelGCThreads, 1);
2802   for (int i = 0; i < n_queues; i++) {
2803     _worker_cset_start_region[i] = NULL;
2804     _worker_cset_start_region_time_stamp[i] = 0;
2805   }
2806 }
2807 
2808 // Given the id of a worker, obtain or calculate a suitable
2809 // starting region for iterating over the current collection set.
2810 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2811   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2812 
2813   HeapRegion* result = NULL;
2814   unsigned gc_time_stamp = get_gc_time_stamp();
2815 
2816   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2817     // Cached starting region for current worker was set
2818     // during the current pause - so it's valid.
2819     // Note: the cached starting heap region may be NULL
2820     // (when the collection set is empty).
2821     result = _worker_cset_start_region[worker_i];
2822     assert(result == NULL || result->in_collection_set(), "sanity");
2823     return result;
2824   }
2825 
2826   // The cached entry was not valid so let's calculate
2827   // a suitable starting heap region for this worker.
2828 
2829   // We want the parallel threads to start their collection
2830   // set iteration at different collection set regions to
2831   // avoid contention.
2832   // If we have:
2833   //          n collection set regions
2834   //          p threads
2835   // Then thread t will start at region floor ((t * n) / p)
2836 
2837   result = g1_policy()->collection_set();
2838   if (G1CollectedHeap::use_parallel_gc_threads()) {
2839     uint cs_size = g1_policy()->cset_region_length();
2840     uint active_workers = workers()->active_workers();
2841     assert(UseDynamicNumberOfGCThreads ||
2842              active_workers == workers()->total_workers(),
2843              "Unless dynamic should use total workers");
2844 
2845     uint end_ind   = (cs_size * worker_i) / active_workers;
2846     uint start_ind = 0;
2847 
2848     if (worker_i > 0 &&
2849         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2850       // Previous workers starting region is valid
2851       // so let's iterate from there
2852       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2853       result = _worker_cset_start_region[worker_i - 1];
2854     }
2855 
2856     for (uint i = start_ind; i < end_ind; i++) {
2857       result = result->next_in_collection_set();
2858     }
2859   }
2860 
2861   // Note: the calculated starting heap region may be NULL
2862   // (when the collection set is empty).
2863   assert(result == NULL || result->in_collection_set(), "sanity");
2864   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2865          "should be updated only once per pause");
2866   _worker_cset_start_region[worker_i] = result;
2867   OrderAccess::storestore();
2868   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2869   return result;
2870 }
2871 
2872 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2873                                                      uint no_of_par_workers) {
2874   uint worker_num =
2875            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2876   assert(UseDynamicNumberOfGCThreads ||
2877          no_of_par_workers == workers()->total_workers(),
2878          "Non dynamic should use fixed number of workers");
2879   const uint start_index = n_regions() * worker_i / worker_num;
2880   return region_at(start_index);
2881 }
2882 
2883 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2884   HeapRegion* r = g1_policy()->collection_set();
2885   while (r != NULL) {
2886     HeapRegion* next = r->next_in_collection_set();
2887     if (cl->doHeapRegion(r)) {
2888       cl->incomplete();
2889       return;
2890     }
2891     r = next;
2892   }
2893 }
2894 
2895 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2896                                                   HeapRegionClosure *cl) {
2897   if (r == NULL) {
2898     // The CSet is empty so there's nothing to do.
2899     return;
2900   }
2901 
2902   assert(r->in_collection_set(),
2903          "Start region must be a member of the collection set.");
2904   HeapRegion* cur = r;
2905   while (cur != NULL) {
2906     HeapRegion* next = cur->next_in_collection_set();
2907     if (cl->doHeapRegion(cur) && false) {
2908       cl->incomplete();
2909       return;
2910     }
2911     cur = next;
2912   }
2913   cur = g1_policy()->collection_set();
2914   while (cur != r) {
2915     HeapRegion* next = cur->next_in_collection_set();
2916     if (cl->doHeapRegion(cur) && false) {
2917       cl->incomplete();
2918       return;
2919     }
2920     cur = next;
2921   }
2922 }
2923 
2924 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2925   return n_regions() > 0 ? region_at(0) : NULL;
2926 }
2927 
2928 
2929 Space* G1CollectedHeap::space_containing(const void* addr) const {
2930   Space* res = heap_region_containing(addr);
2931   return res;
2932 }
2933 
2934 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2935   Space* sp = space_containing(addr);
2936   if (sp != NULL) {
2937     return sp->block_start(addr);
2938   }
2939   return NULL;
2940 }
2941 
2942 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2943   Space* sp = space_containing(addr);
2944   assert(sp != NULL, "block_size of address outside of heap");
2945   return sp->block_size(addr);
2946 }
2947 
2948 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2949   Space* sp = space_containing(addr);
2950   return sp->block_is_obj(addr);
2951 }
2952 
2953 bool G1CollectedHeap::supports_tlab_allocation() const {
2954   return true;
2955 }
2956 
2957 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2958   return HeapRegion::GrainBytes;
2959 }
2960 
2961 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2962   // Return the remaining space in the cur alloc region, but not less than
2963   // the min TLAB size.
2964 
2965   // Also, this value can be at most the humongous object threshold,
2966   // since we can't allow tlabs to grow big enough to accomodate
2967   // humongous objects.
2968 
2969   HeapRegion* hr = _mutator_alloc_region.get();
2970   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2971   if (hr == NULL) {
2972     return max_tlab_size;
2973   } else {
2974     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2975   }
2976 }
2977 
2978 size_t G1CollectedHeap::max_capacity() const {
2979   return _g1_reserved.byte_size();
2980 }
2981 
2982 jlong G1CollectedHeap::millis_since_last_gc() {
2983   // assert(false, "NYI");
2984   return 0;
2985 }
2986 
2987 void G1CollectedHeap::prepare_for_verify() {
2988   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2989     ensure_parsability(false);
2990   }
2991   g1_rem_set()->prepare_for_verify();
2992 }
2993 
2994 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2995                                               VerifyOption vo) {
2996   switch (vo) {
2997   case VerifyOption_G1UsePrevMarking:
2998     return hr->obj_allocated_since_prev_marking(obj);
2999   case VerifyOption_G1UseNextMarking:
3000     return hr->obj_allocated_since_next_marking(obj);
3001   case VerifyOption_G1UseMarkWord:
3002     return false;
3003   default:
3004     ShouldNotReachHere();
3005   }
3006   return false; // keep some compilers happy
3007 }
3008 
3009 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3010   switch (vo) {
3011   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3012   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3013   case VerifyOption_G1UseMarkWord:    return NULL;
3014   default:                            ShouldNotReachHere();
3015   }
3016   return NULL; // keep some compilers happy
3017 }
3018 
3019 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3020   switch (vo) {
3021   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3022   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3023   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3024   default:                            ShouldNotReachHere();
3025   }
3026   return false; // keep some compilers happy
3027 }
3028 
3029 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3030   switch (vo) {
3031   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3032   case VerifyOption_G1UseNextMarking: return "NTAMS";
3033   case VerifyOption_G1UseMarkWord:    return "NONE";
3034   default:                            ShouldNotReachHere();
3035   }
3036   return NULL; // keep some compilers happy
3037 }
3038 
3039 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3040 //       pass it as the perm_blk to SharedHeap::process_strong_roots.
3041 //       When process_strong_roots stop calling perm_blk->younger_refs_iterate
3042 //       we can change this closure to extend the simpler OopClosure.
3043 class VerifyRootsClosure: public OopsInGenClosure {
3044 private:
3045   G1CollectedHeap* _g1h;
3046   VerifyOption     _vo;
3047   bool             _failures;
3048 public:
3049   // _vo == UsePrevMarking -> use "prev" marking information,
3050   // _vo == UseNextMarking -> use "next" marking information,
3051   // _vo == UseMarkWord    -> use mark word from object header.
3052   VerifyRootsClosure(VerifyOption vo) :
3053     _g1h(G1CollectedHeap::heap()),
3054     _vo(vo),
3055     _failures(false) { }
3056 
3057   bool failures() { return _failures; }
3058 
3059   template <class T> void do_oop_nv(T* p) {
3060     T heap_oop = oopDesc::load_heap_oop(p);
3061     if (!oopDesc::is_null(heap_oop)) {
3062       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3063       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3064         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3065                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3066         if (_vo == VerifyOption_G1UseMarkWord) {
3067           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3068         }
3069         obj->print_on(gclog_or_tty);
3070         _failures = true;
3071       }
3072     }
3073   }
3074 
3075   void do_oop(oop* p)       { do_oop_nv(p); }
3076   void do_oop(narrowOop* p) { do_oop_nv(p); }
3077 };
3078 
3079 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3080   G1CollectedHeap* _g1h;
3081   OopClosure* _root_cl;
3082   nmethod* _nm;
3083   VerifyOption _vo;
3084   bool _failures;
3085 
3086   template <class T> void do_oop_work(T* p) {
3087     // First verify that this root is live
3088     _root_cl->do_oop(p);
3089 
3090     if (!G1VerifyHeapRegionCodeRoots) {
3091       // We're not verifying the code roots attached to heap region.
3092       return;
3093     }
3094 
3095     // Don't check the code roots during marking verification in a full GC
3096     if (_vo == VerifyOption_G1UseMarkWord) {
3097       return;
3098     }
3099 
3100     // Now verify that the current nmethod (which contains p) is
3101     // in the code root list of the heap region containing the
3102     // object referenced by p.
3103 
3104     T heap_oop = oopDesc::load_heap_oop(p);
3105     if (!oopDesc::is_null(heap_oop)) {
3106       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3107       
3108       // Now fetch the region containing the object
3109       HeapRegion* hr = _g1h->heap_region_containing(obj);
3110       // Verify that the strong code root list for this region
3111       // contains the nmethod
3112       if (!hr->strong_code_root_list()->contains(_nm)) {
3113         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3114                               "from nmethod "PTR_FORMAT" not in strong "
3115                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3116                               p, _nm, hr->bottom(), hr->end());
3117         _failures = true;
3118       }
3119     }
3120   }
3121 
3122 public:
3123   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3124     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3125 
3126   void do_oop(oop* p) { do_oop_work(p); }
3127   void do_oop(narrowOop* p) { do_oop_work(p); }
3128 
3129   void set_nmethod(nmethod* nm) { _nm = nm; }
3130   bool failures() { return _failures; }
3131 };
3132 
3133 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3134   G1VerifyCodeRootOopClosure* _oop_cl;
3135 
3136 public:
3137   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3138     _oop_cl(oop_cl) {}
3139 
3140   void do_code_blob(CodeBlob* cb) {
3141     nmethod* nm = cb->as_nmethod_or_null();
3142     if (nm != NULL) {
3143       _oop_cl->set_nmethod(nm);
3144       nm->oops_do(_oop_cl);
3145     }
3146   }
3147 };
3148 
3149 class YoungRefCounterClosure : public OopClosure {
3150   G1CollectedHeap* _g1h;
3151   int              _count;
3152  public:
3153   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3154   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3155   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3156 
3157   int count() { return _count; }
3158   void reset_count() { _count = 0; };
3159 };
3160 
3161 class VerifyKlassClosure: public KlassClosure {
3162   YoungRefCounterClosure _young_ref_counter_closure;
3163   OopClosure *_oop_closure;
3164  public:
3165   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3166   void do_klass(Klass* k) {
3167     k->oops_do(_oop_closure);
3168 
3169     _young_ref_counter_closure.reset_count();
3170     k->oops_do(&_young_ref_counter_closure);
3171     if (_young_ref_counter_closure.count() > 0) {
3172       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3173     }
3174   }
3175 };
3176 
3177 class VerifyLivenessOopClosure: public OopClosure {
3178   G1CollectedHeap* _g1h;
3179   VerifyOption _vo;
3180 public:
3181   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3182     _g1h(g1h), _vo(vo)
3183   { }
3184   void do_oop(narrowOop *p) { do_oop_work(p); }
3185   void do_oop(      oop *p) { do_oop_work(p); }
3186 
3187   template <class T> void do_oop_work(T *p) {
3188     oop obj = oopDesc::load_decode_heap_oop(p);
3189     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3190               "Dead object referenced by a not dead object");
3191   }
3192 };
3193 
3194 class VerifyObjsInRegionClosure: public ObjectClosure {
3195 private:
3196   G1CollectedHeap* _g1h;
3197   size_t _live_bytes;
3198   HeapRegion *_hr;
3199   VerifyOption _vo;
3200 public:
3201   // _vo == UsePrevMarking -> use "prev" marking information,
3202   // _vo == UseNextMarking -> use "next" marking information,
3203   // _vo == UseMarkWord    -> use mark word from object header.
3204   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3205     : _live_bytes(0), _hr(hr), _vo(vo) {
3206     _g1h = G1CollectedHeap::heap();
3207   }
3208   void do_object(oop o) {
3209     VerifyLivenessOopClosure isLive(_g1h, _vo);
3210     assert(o != NULL, "Huh?");
3211     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3212       // If the object is alive according to the mark word,
3213       // then verify that the marking information agrees.
3214       // Note we can't verify the contra-positive of the
3215       // above: if the object is dead (according to the mark
3216       // word), it may not be marked, or may have been marked
3217       // but has since became dead, or may have been allocated
3218       // since the last marking.
3219       if (_vo == VerifyOption_G1UseMarkWord) {
3220         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3221       }
3222 
3223       o->oop_iterate_no_header(&isLive);
3224       if (!_hr->obj_allocated_since_prev_marking(o)) {
3225         size_t obj_size = o->size();    // Make sure we don't overflow
3226         _live_bytes += (obj_size * HeapWordSize);
3227       }
3228     }
3229   }
3230   size_t live_bytes() { return _live_bytes; }
3231 };
3232 
3233 class PrintObjsInRegionClosure : public ObjectClosure {
3234   HeapRegion *_hr;
3235   G1CollectedHeap *_g1;
3236 public:
3237   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3238     _g1 = G1CollectedHeap::heap();
3239   };
3240 
3241   void do_object(oop o) {
3242     if (o != NULL) {
3243       HeapWord *start = (HeapWord *) o;
3244       size_t word_sz = o->size();
3245       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3246                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3247                           (void*) o, word_sz,
3248                           _g1->isMarkedPrev(o),
3249                           _g1->isMarkedNext(o),
3250                           _hr->obj_allocated_since_prev_marking(o));
3251       HeapWord *end = start + word_sz;
3252       HeapWord *cur;
3253       int *val;
3254       for (cur = start; cur < end; cur++) {
3255         val = (int *) cur;
3256         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3257       }
3258     }
3259   }
3260 };
3261 
3262 class VerifyRegionClosure: public HeapRegionClosure {
3263 private:
3264   bool             _par;
3265   VerifyOption     _vo;
3266   bool             _failures;
3267 public:
3268   // _vo == UsePrevMarking -> use "prev" marking information,
3269   // _vo == UseNextMarking -> use "next" marking information,
3270   // _vo == UseMarkWord    -> use mark word from object header.
3271   VerifyRegionClosure(bool par, VerifyOption vo)
3272     : _par(par),
3273       _vo(vo),
3274       _failures(false) {}
3275 
3276   bool failures() {
3277     return _failures;
3278   }
3279 
3280   bool doHeapRegion(HeapRegion* r) {
3281     if (!r->continuesHumongous()) {
3282       bool failures = false;
3283       r->verify(_vo, &failures);
3284       if (failures) {
3285         _failures = true;
3286       } else {
3287         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3288         r->object_iterate(&not_dead_yet_cl);
3289         if (_vo != VerifyOption_G1UseNextMarking) {
3290           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3291             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3292                                    "max_live_bytes "SIZE_FORMAT" "
3293                                    "< calculated "SIZE_FORMAT,
3294                                    r->bottom(), r->end(),
3295                                    r->max_live_bytes(),
3296                                  not_dead_yet_cl.live_bytes());
3297             _failures = true;
3298           }
3299         } else {
3300           // When vo == UseNextMarking we cannot currently do a sanity
3301           // check on the live bytes as the calculation has not been
3302           // finalized yet.
3303         }
3304       }
3305     }
3306     return false; // stop the region iteration if we hit a failure
3307   }
3308 };
3309 
3310 // This is the task used for parallel verification of the heap regions
3311 
3312 class G1ParVerifyTask: public AbstractGangTask {
3313 private:
3314   G1CollectedHeap* _g1h;
3315   VerifyOption     _vo;
3316   bool             _failures;
3317 
3318 public:
3319   // _vo == UsePrevMarking -> use "prev" marking information,
3320   // _vo == UseNextMarking -> use "next" marking information,
3321   // _vo == UseMarkWord    -> use mark word from object header.
3322   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3323     AbstractGangTask("Parallel verify task"),
3324     _g1h(g1h),
3325     _vo(vo),
3326     _failures(false) { }
3327 
3328   bool failures() {
3329     return _failures;
3330   }
3331 
3332   void work(uint worker_id) {
3333     HandleMark hm;
3334     VerifyRegionClosure blk(true, _vo);
3335     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3336                                           _g1h->workers()->active_workers(),
3337                                           HeapRegion::ParVerifyClaimValue);
3338     if (blk.failures()) {
3339       _failures = true;
3340     }
3341   }
3342 };
3343 
3344 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3345   if (SafepointSynchronize::is_at_safepoint()) {
3346     assert(Thread::current()->is_VM_thread(),
3347            "Expected to be executed serially by the VM thread at this point");
3348 
3349     if (!silent) { gclog_or_tty->print("Roots "); }
3350     VerifyRootsClosure rootsCl(vo);
3351     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3352     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3353     VerifyKlassClosure klassCl(this, &rootsCl);
3354 
3355     // We apply the relevant closures to all the oops in the
3356     // system dictionary, the string table and the code cache.
3357     const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3358 
3359     // Need cleared claim bits for the strong roots processing
3360     ClassLoaderDataGraph::clear_claimed_marks();
3361 
3362     process_strong_roots(true,      // activate StrongRootsScope
3363                          false,     // we set "is scavenging" to false,
3364                                     // so we don't reset the dirty cards.
3365                          ScanningOption(so),  // roots scanning options
3366                          &rootsCl,
3367                          &blobsCl,
3368                          &klassCl
3369                          );
3370 
3371     bool failures = rootsCl.failures() || codeRootsCl.failures();
3372 
3373     if (vo != VerifyOption_G1UseMarkWord) {
3374       // If we're verifying during a full GC then the region sets
3375       // will have been torn down at the start of the GC. Therefore
3376       // verifying the region sets will fail. So we only verify
3377       // the region sets when not in a full GC.
3378       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3379       verify_region_sets();
3380     }
3381 
3382     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3383     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3384       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3385              "sanity check");
3386 
3387       G1ParVerifyTask task(this, vo);
3388       assert(UseDynamicNumberOfGCThreads ||
3389         workers()->active_workers() == workers()->total_workers(),
3390         "If not dynamic should be using all the workers");
3391       int n_workers = workers()->active_workers();
3392       set_par_threads(n_workers);
3393       workers()->run_task(&task);
3394       set_par_threads(0);
3395       if (task.failures()) {
3396         failures = true;
3397       }
3398 
3399       // Checks that the expected amount of parallel work was done.
3400       // The implication is that n_workers is > 0.
3401       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3402              "sanity check");
3403 
3404       reset_heap_region_claim_values();
3405 
3406       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3407              "sanity check");
3408     } else {
3409       VerifyRegionClosure blk(false, vo);
3410       heap_region_iterate(&blk);
3411       if (blk.failures()) {
3412         failures = true;
3413       }
3414     }
3415     if (!silent) gclog_or_tty->print("RemSet ");
3416     rem_set()->verify();
3417 
3418     if (failures) {
3419       gclog_or_tty->print_cr("Heap:");
3420       // It helps to have the per-region information in the output to
3421       // help us track down what went wrong. This is why we call
3422       // print_extended_on() instead of print_on().
3423       print_extended_on(gclog_or_tty);
3424       gclog_or_tty->print_cr("");
3425 #ifndef PRODUCT
3426       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3427         concurrent_mark()->print_reachable("at-verification-failure",
3428                                            vo, false /* all */);
3429       }
3430 #endif
3431       gclog_or_tty->flush();
3432     }
3433     guarantee(!failures, "there should not have been any failures");
3434   } else {
3435     if (!silent)
3436       gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3437   }
3438 }
3439 
3440 void G1CollectedHeap::verify(bool silent) {
3441   verify(silent, VerifyOption_G1UsePrevMarking);
3442 }
3443 
3444 double G1CollectedHeap::verify(bool guard, const char* msg) {
3445   double verify_time_ms = 0.0;
3446 
3447   if (guard && total_collections() >= VerifyGCStartAt) {
3448     double verify_start = os::elapsedTime();
3449     HandleMark hm;  // Discard invalid handles created during verification
3450     prepare_for_verify();
3451     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3452     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3453   }
3454 
3455   return verify_time_ms;
3456 }
3457 
3458 void G1CollectedHeap::verify_before_gc() {
3459   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3460   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3461 }
3462 
3463 void G1CollectedHeap::verify_after_gc() {
3464   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3465   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3466 }
3467 
3468 class PrintRegionClosure: public HeapRegionClosure {
3469   outputStream* _st;
3470 public:
3471   PrintRegionClosure(outputStream* st) : _st(st) {}
3472   bool doHeapRegion(HeapRegion* r) {
3473     r->print_on(_st);
3474     return false;
3475   }
3476 };
3477 
3478 void G1CollectedHeap::print_on(outputStream* st) const {
3479   st->print(" %-20s", "garbage-first heap");
3480   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3481             capacity()/K, used_unlocked()/K);
3482   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3483             _g1_storage.low_boundary(),
3484             _g1_storage.high(),
3485             _g1_storage.high_boundary());
3486   st->cr();
3487   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3488   uint young_regions = _young_list->length();
3489   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3490             (size_t) young_regions * HeapRegion::GrainBytes / K);
3491   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3492   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3493             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3494   st->cr();
3495   MetaspaceAux::print_on(st);
3496 }
3497 
3498 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3499   print_on(st);
3500 
3501   // Print the per-region information.
3502   st->cr();
3503   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3504                "HS=humongous(starts), HC=humongous(continues), "
3505                "CS=collection set, F=free, TS=gc time stamp, "
3506                "PTAMS=previous top-at-mark-start, "
3507                "NTAMS=next top-at-mark-start)");
3508   PrintRegionClosure blk(st);
3509   heap_region_iterate(&blk);
3510 }
3511 
3512 void G1CollectedHeap::print_on_error(outputStream* st) const {
3513   this->CollectedHeap::print_on_error(st);
3514 
3515   if (_cm != NULL) {
3516     st->cr();
3517     _cm->print_on_error(st);
3518   }
3519 }
3520 
3521 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3522   if (G1CollectedHeap::use_parallel_gc_threads()) {
3523     workers()->print_worker_threads_on(st);
3524   }
3525   _cmThread->print_on(st);
3526   st->cr();
3527   _cm->print_worker_threads_on(st);
3528   _cg1r->print_worker_threads_on(st);
3529 }
3530 
3531 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3532   if (G1CollectedHeap::use_parallel_gc_threads()) {
3533     workers()->threads_do(tc);
3534   }
3535   tc->do_thread(_cmThread);
3536   _cg1r->threads_do(tc);
3537 }
3538 
3539 void G1CollectedHeap::print_tracing_info() const {
3540   // We'll overload this to mean "trace GC pause statistics."
3541   if (TraceGen0Time || TraceGen1Time) {
3542     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3543     // to that.
3544     g1_policy()->print_tracing_info();
3545   }
3546   if (G1SummarizeRSetStats) {
3547     g1_rem_set()->print_summary_info();
3548   }
3549   if (G1SummarizeConcMark) {
3550     concurrent_mark()->print_summary_info();
3551   }
3552   g1_policy()->print_yg_surv_rate_info();
3553   SpecializationStats::print();
3554 }
3555 
3556 #ifndef PRODUCT
3557 // Helpful for debugging RSet issues.
3558 
3559 class PrintRSetsClosure : public HeapRegionClosure {
3560 private:
3561   const char* _msg;
3562   size_t _occupied_sum;
3563 
3564 public:
3565   bool doHeapRegion(HeapRegion* r) {
3566     HeapRegionRemSet* hrrs = r->rem_set();
3567     size_t occupied = hrrs->occupied();
3568     _occupied_sum += occupied;
3569 
3570     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3571                            HR_FORMAT_PARAMS(r));
3572     if (occupied == 0) {
3573       gclog_or_tty->print_cr("  RSet is empty");
3574     } else {
3575       hrrs->print();
3576     }
3577     gclog_or_tty->print_cr("----------");
3578     return false;
3579   }
3580 
3581   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3582     gclog_or_tty->cr();
3583     gclog_or_tty->print_cr("========================================");
3584     gclog_or_tty->print_cr(msg);
3585     gclog_or_tty->cr();
3586   }
3587 
3588   ~PrintRSetsClosure() {
3589     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3590     gclog_or_tty->print_cr("========================================");
3591     gclog_or_tty->cr();
3592   }
3593 };
3594 
3595 void G1CollectedHeap::print_cset_rsets() {
3596   PrintRSetsClosure cl("Printing CSet RSets");
3597   collection_set_iterate(&cl);
3598 }
3599 
3600 void G1CollectedHeap::print_all_rsets() {
3601   PrintRSetsClosure cl("Printing All RSets");;
3602   heap_region_iterate(&cl);
3603 }
3604 #endif // PRODUCT
3605 
3606 G1CollectedHeap* G1CollectedHeap::heap() {
3607   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3608          "not a garbage-first heap");
3609   return _g1h;
3610 }
3611 
3612 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3613   // always_do_update_barrier = false;
3614   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3615   // Call allocation profiler
3616   AllocationProfiler::iterate_since_last_gc();
3617   // Fill TLAB's and such
3618   ensure_parsability(true);
3619 }
3620 
3621 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3622 
3623   if (G1SummarizeRSetStats &&
3624       (G1SummarizeRSetStatsPeriod > 0) &&
3625       // we are at the end of the GC. Total collections has already been increased.
3626       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3627     g1_rem_set()->print_periodic_summary_info();
3628   }
3629 
3630   // FIXME: what is this about?
3631   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3632   // is set.
3633   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3634                         "derived pointer present"));
3635   // always_do_update_barrier = true;
3636 
3637   // We have just completed a GC. Update the soft reference
3638   // policy with the new heap occupancy
3639   Universe::update_heap_info_at_gc();
3640 }
3641 
3642 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3643                                                unsigned int gc_count_before,
3644                                                bool* succeeded) {
3645   assert_heap_not_locked_and_not_at_safepoint();
3646   g1_policy()->record_stop_world_start();
3647   VM_G1IncCollectionPause op(gc_count_before,
3648                              word_size,
3649                              false, /* should_initiate_conc_mark */
3650                              g1_policy()->max_pause_time_ms(),
3651                              GCCause::_g1_inc_collection_pause);
3652   VMThread::execute(&op);
3653 
3654   HeapWord* result = op.result();
3655   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3656   assert(result == NULL || ret_succeeded,
3657          "the result should be NULL if the VM did not succeed");
3658   *succeeded = ret_succeeded;
3659 
3660   assert_heap_not_locked();
3661   return result;
3662 }
3663 
3664 void
3665 G1CollectedHeap::doConcurrentMark() {
3666   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3667   if (!_cmThread->in_progress()) {
3668     _cmThread->set_started();
3669     CGC_lock->notify();
3670   }
3671 }
3672 
3673 size_t G1CollectedHeap::pending_card_num() {
3674   size_t extra_cards = 0;
3675   JavaThread *curr = Threads::first();
3676   while (curr != NULL) {
3677     DirtyCardQueue& dcq = curr->dirty_card_queue();
3678     extra_cards += dcq.size();
3679     curr = curr->next();
3680   }
3681   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3682   size_t buffer_size = dcqs.buffer_size();
3683   size_t buffer_num = dcqs.completed_buffers_num();
3684 
3685   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3686   // in bytes - not the number of 'entries'. We need to convert
3687   // into a number of cards.
3688   return (buffer_size * buffer_num + extra_cards) / oopSize;
3689 }
3690 
3691 size_t G1CollectedHeap::cards_scanned() {
3692   return g1_rem_set()->cardsScanned();
3693 }
3694 
3695 void
3696 G1CollectedHeap::setup_surviving_young_words() {
3697   assert(_surviving_young_words == NULL, "pre-condition");
3698   uint array_length = g1_policy()->young_cset_region_length();
3699   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3700   if (_surviving_young_words == NULL) {
3701     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3702                           "Not enough space for young surv words summary.");
3703   }
3704   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3705 #ifdef ASSERT
3706   for (uint i = 0;  i < array_length; ++i) {
3707     assert( _surviving_young_words[i] == 0, "memset above" );
3708   }
3709 #endif // !ASSERT
3710 }
3711 
3712 void
3713 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3714   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3715   uint array_length = g1_policy()->young_cset_region_length();
3716   for (uint i = 0; i < array_length; ++i) {
3717     _surviving_young_words[i] += surv_young_words[i];
3718   }
3719 }
3720 
3721 void
3722 G1CollectedHeap::cleanup_surviving_young_words() {
3723   guarantee( _surviving_young_words != NULL, "pre-condition" );
3724   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3725   _surviving_young_words = NULL;
3726 }
3727 
3728 #ifdef ASSERT
3729 class VerifyCSetClosure: public HeapRegionClosure {
3730 public:
3731   bool doHeapRegion(HeapRegion* hr) {
3732     // Here we check that the CSet region's RSet is ready for parallel
3733     // iteration. The fields that we'll verify are only manipulated
3734     // when the region is part of a CSet and is collected. Afterwards,
3735     // we reset these fields when we clear the region's RSet (when the
3736     // region is freed) so they are ready when the region is
3737     // re-allocated. The only exception to this is if there's an
3738     // evacuation failure and instead of freeing the region we leave
3739     // it in the heap. In that case, we reset these fields during
3740     // evacuation failure handling.
3741     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3742 
3743     // Here's a good place to add any other checks we'd like to
3744     // perform on CSet regions.
3745     return false;
3746   }
3747 };
3748 #endif // ASSERT
3749 
3750 #if TASKQUEUE_STATS
3751 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3752   st->print_raw_cr("GC Task Stats");
3753   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3754   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3755 }
3756 
3757 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3758   print_taskqueue_stats_hdr(st);
3759 
3760   TaskQueueStats totals;
3761   const int n = workers() != NULL ? workers()->total_workers() : 1;
3762   for (int i = 0; i < n; ++i) {
3763     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3764     totals += task_queue(i)->stats;
3765   }
3766   st->print_raw("tot "); totals.print(st); st->cr();
3767 
3768   DEBUG_ONLY(totals.verify());
3769 }
3770 
3771 void G1CollectedHeap::reset_taskqueue_stats() {
3772   const int n = workers() != NULL ? workers()->total_workers() : 1;
3773   for (int i = 0; i < n; ++i) {
3774     task_queue(i)->stats.reset();
3775   }
3776 }
3777 #endif // TASKQUEUE_STATS
3778 
3779 void G1CollectedHeap::log_gc_header() {
3780   if (!G1Log::fine()) {
3781     return;
3782   }
3783 
3784   gclog_or_tty->date_stamp(PrintGCDateStamps);
3785   gclog_or_tty->stamp(PrintGCTimeStamps);
3786 
3787   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3788     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3789     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3790 
3791   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3792 }
3793 
3794 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3795   if (!G1Log::fine()) {
3796     return;
3797   }
3798 
3799   if (G1Log::finer()) {
3800     if (evacuation_failed()) {
3801       gclog_or_tty->print(" (to-space exhausted)");
3802     }
3803     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3804     g1_policy()->phase_times()->note_gc_end();
3805     g1_policy()->phase_times()->print(pause_time_sec);
3806     g1_policy()->print_detailed_heap_transition();
3807   } else {
3808     if (evacuation_failed()) {
3809       gclog_or_tty->print("--");
3810     }
3811     g1_policy()->print_heap_transition();
3812     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3813   }
3814   gclog_or_tty->flush();
3815 }
3816 
3817 bool
3818 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3819   assert_at_safepoint(true /* should_be_vm_thread */);
3820   guarantee(!is_gc_active(), "collection is not reentrant");
3821 
3822   if (GC_locker::check_active_before_gc()) {
3823     return false;
3824   }
3825 
3826   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3827   ResourceMark rm;
3828 
3829   print_heap_before_gc();
3830 
3831   HRSPhaseSetter x(HRSPhaseEvacuation);
3832   verify_region_sets_optional();
3833   verify_dirty_young_regions();
3834 
3835   // This call will decide whether this pause is an initial-mark
3836   // pause. If it is, during_initial_mark_pause() will return true
3837   // for the duration of this pause.
3838   g1_policy()->decide_on_conc_mark_initiation();
3839 
3840   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3841   assert(!g1_policy()->during_initial_mark_pause() ||
3842           g1_policy()->gcs_are_young(), "sanity");
3843 
3844   // We also do not allow mixed GCs during marking.
3845   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3846 
3847   // Record whether this pause is an initial mark. When the current
3848   // thread has completed its logging output and it's safe to signal
3849   // the CM thread, the flag's value in the policy has been reset.
3850   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3851 
3852   // Inner scope for scope based logging, timers, and stats collection
3853   {
3854     if (g1_policy()->during_initial_mark_pause()) {
3855       // We are about to start a marking cycle, so we increment the
3856       // full collection counter.
3857       increment_old_marking_cycles_started();
3858     }
3859     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3860 
3861     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3862                                 workers()->active_workers() : 1);
3863     double pause_start_sec = os::elapsedTime();
3864     g1_policy()->phase_times()->note_gc_start(active_workers);
3865     log_gc_header();
3866 
3867     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3868     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3869 
3870     // If the secondary_free_list is not empty, append it to the
3871     // free_list. No need to wait for the cleanup operation to finish;
3872     // the region allocation code will check the secondary_free_list
3873     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3874     // set, skip this step so that the region allocation code has to
3875     // get entries from the secondary_free_list.
3876     if (!G1StressConcRegionFreeing) {
3877       append_secondary_free_list_if_not_empty_with_lock();
3878     }
3879 
3880     assert(check_young_list_well_formed(), "young list should be well formed");
3881     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3882            "sanity check");
3883 
3884     // Don't dynamically change the number of GC threads this early.  A value of
3885     // 0 is used to indicate serial work.  When parallel work is done,
3886     // it will be set.
3887 
3888     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3889       IsGCActiveMark x;
3890 
3891       gc_prologue(false);
3892       increment_total_collections(false /* full gc */);
3893       increment_gc_time_stamp();
3894 
3895       verify_before_gc();
3896 
3897       COMPILER2_PRESENT(DerivedPointerTable::clear());
3898 
3899       // Please see comment in g1CollectedHeap.hpp and
3900       // G1CollectedHeap::ref_processing_init() to see how
3901       // reference processing currently works in G1.
3902 
3903       // Enable discovery in the STW reference processor
3904       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3905                                             true /*verify_no_refs*/);
3906 
3907       {
3908         // We want to temporarily turn off discovery by the
3909         // CM ref processor, if necessary, and turn it back on
3910         // on again later if we do. Using a scoped
3911         // NoRefDiscovery object will do this.
3912         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3913 
3914         // Forget the current alloc region (we might even choose it to be part
3915         // of the collection set!).
3916         release_mutator_alloc_region();
3917 
3918         // We should call this after we retire the mutator alloc
3919         // region(s) so that all the ALLOC / RETIRE events are generated
3920         // before the start GC event.
3921         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3922 
3923         // This timing is only used by the ergonomics to handle our pause target.
3924         // It is unclear why this should not include the full pause. We will
3925         // investigate this in CR 7178365.
3926         //
3927         // Preserving the old comment here if that helps the investigation:
3928         //
3929         // The elapsed time induced by the start time below deliberately elides
3930         // the possible verification above.
3931         double sample_start_time_sec = os::elapsedTime();
3932 
3933 #if YOUNG_LIST_VERBOSE
3934         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3935         _young_list->print();
3936         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3937 #endif // YOUNG_LIST_VERBOSE
3938 
3939         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3940 
3941         double scan_wait_start = os::elapsedTime();
3942         // We have to wait until the CM threads finish scanning the
3943         // root regions as it's the only way to ensure that all the
3944         // objects on them have been correctly scanned before we start
3945         // moving them during the GC.
3946         bool waited = _cm->root_regions()->wait_until_scan_finished();
3947         double wait_time_ms = 0.0;
3948         if (waited) {
3949           double scan_wait_end = os::elapsedTime();
3950           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3951         }
3952         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3953 
3954 #if YOUNG_LIST_VERBOSE
3955         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3956         _young_list->print();
3957 #endif // YOUNG_LIST_VERBOSE
3958 
3959         if (g1_policy()->during_initial_mark_pause()) {
3960           concurrent_mark()->checkpointRootsInitialPre();
3961         }
3962 
3963 #if YOUNG_LIST_VERBOSE
3964         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3965         _young_list->print();
3966         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3967 #endif // YOUNG_LIST_VERBOSE
3968 
3969         g1_policy()->finalize_cset(target_pause_time_ms);
3970 
3971         _cm->note_start_of_gc();
3972         // We should not verify the per-thread SATB buffers given that
3973         // we have not filtered them yet (we'll do so during the
3974         // GC). We also call this after finalize_cset() to
3975         // ensure that the CSet has been finalized.
3976         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3977                                  true  /* verify_enqueued_buffers */,
3978                                  false /* verify_thread_buffers */,
3979                                  true  /* verify_fingers */);
3980 
3981         if (_hr_printer.is_active()) {
3982           HeapRegion* hr = g1_policy()->collection_set();
3983           while (hr != NULL) {
3984             G1HRPrinter::RegionType type;
3985             if (!hr->is_young()) {
3986               type = G1HRPrinter::Old;
3987             } else if (hr->is_survivor()) {
3988               type = G1HRPrinter::Survivor;
3989             } else {
3990               type = G1HRPrinter::Eden;
3991             }
3992             _hr_printer.cset(hr);
3993             hr = hr->next_in_collection_set();
3994           }
3995         }
3996 
3997 #ifdef ASSERT
3998         VerifyCSetClosure cl;
3999         collection_set_iterate(&cl);
4000 #endif // ASSERT
4001 
4002         setup_surviving_young_words();
4003 
4004         // Initialize the GC alloc regions.
4005         init_gc_alloc_regions();
4006 
4007         // Actually do the work...
4008         evacuate_collection_set();
4009 
4010         // We do this to mainly verify the per-thread SATB buffers
4011         // (which have been filtered by now) since we didn't verify
4012         // them earlier. No point in re-checking the stacks / enqueued
4013         // buffers given that the CSet has not changed since last time
4014         // we checked.
4015         _cm->verify_no_cset_oops(false /* verify_stacks */,
4016                                  false /* verify_enqueued_buffers */,
4017                                  true  /* verify_thread_buffers */,
4018                                  true  /* verify_fingers */);
4019 
4020         free_collection_set(g1_policy()->collection_set());
4021         g1_policy()->clear_collection_set();
4022 
4023         cleanup_surviving_young_words();
4024 
4025         // Start a new incremental collection set for the next pause.
4026         g1_policy()->start_incremental_cset_building();
4027 
4028         // Clear the _cset_fast_test bitmap in anticipation of adding
4029         // regions to the incremental collection set for the next
4030         // evacuation pause.
4031         clear_cset_fast_test();
4032 
4033         _young_list->reset_sampled_info();
4034 
4035         // Don't check the whole heap at this point as the
4036         // GC alloc regions from this pause have been tagged
4037         // as survivors and moved on to the survivor list.
4038         // Survivor regions will fail the !is_young() check.
4039         assert(check_young_list_empty(false /* check_heap */),
4040           "young list should be empty");
4041 
4042 #if YOUNG_LIST_VERBOSE
4043         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4044         _young_list->print();
4045 #endif // YOUNG_LIST_VERBOSE
4046 
4047         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4048                                             _young_list->first_survivor_region(),
4049                                             _young_list->last_survivor_region());
4050 
4051         _young_list->reset_auxilary_lists();
4052 
4053         if (evacuation_failed()) {
4054           _summary_bytes_used = recalculate_used();
4055         } else {
4056           // The "used" of the the collection set have already been subtracted
4057           // when they were freed.  Add in the bytes evacuated.
4058           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4059         }
4060 
4061         if (g1_policy()->during_initial_mark_pause()) {
4062           // We have to do this before we notify the CM threads that
4063           // they can start working to make sure that all the
4064           // appropriate initialization is done on the CM object.
4065           concurrent_mark()->checkpointRootsInitialPost();
4066           set_marking_started();
4067           // Note that we don't actually trigger the CM thread at
4068           // this point. We do that later when we're sure that
4069           // the current thread has completed its logging output.
4070         }
4071 
4072         allocate_dummy_regions();
4073 
4074 #if YOUNG_LIST_VERBOSE
4075         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4076         _young_list->print();
4077         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4078 #endif // YOUNG_LIST_VERBOSE
4079 
4080         init_mutator_alloc_region();
4081 
4082         {
4083           size_t expand_bytes = g1_policy()->expansion_amount();
4084           if (expand_bytes > 0) {
4085             size_t bytes_before = capacity();
4086             // No need for an ergo verbose message here,
4087             // expansion_amount() does this when it returns a value > 0.
4088             if (!expand(expand_bytes)) {
4089               // We failed to expand the heap so let's verify that
4090               // committed/uncommitted amount match the backing store
4091               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4092               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4093             }
4094           }
4095         }
4096 
4097         // We redo the verificaiton but now wrt to the new CSet which
4098         // has just got initialized after the previous CSet was freed.
4099         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4100                                  true  /* verify_enqueued_buffers */,
4101                                  true  /* verify_thread_buffers */,
4102                                  true  /* verify_fingers */);
4103         _cm->note_end_of_gc();
4104 
4105         // This timing is only used by the ergonomics to handle our pause target.
4106         // It is unclear why this should not include the full pause. We will
4107         // investigate this in CR 7178365.
4108         double sample_end_time_sec = os::elapsedTime();
4109         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4110         g1_policy()->record_collection_pause_end(pause_time_ms);
4111 
4112         MemoryService::track_memory_usage();
4113 
4114         // In prepare_for_verify() below we'll need to scan the deferred
4115         // update buffers to bring the RSets up-to-date if
4116         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4117         // the update buffers we'll probably need to scan cards on the
4118         // regions we just allocated to (i.e., the GC alloc
4119         // regions). However, during the last GC we called
4120         // set_saved_mark() on all the GC alloc regions, so card
4121         // scanning might skip the [saved_mark_word()...top()] area of
4122         // those regions (i.e., the area we allocated objects into
4123         // during the last GC). But it shouldn't. Given that
4124         // saved_mark_word() is conditional on whether the GC time stamp
4125         // on the region is current or not, by incrementing the GC time
4126         // stamp here we invalidate all the GC time stamps on all the
4127         // regions and saved_mark_word() will simply return top() for
4128         // all the regions. This is a nicer way of ensuring this rather
4129         // than iterating over the regions and fixing them. In fact, the
4130         // GC time stamp increment here also ensures that
4131         // saved_mark_word() will return top() between pauses, i.e.,
4132         // during concurrent refinement. So we don't need the
4133         // is_gc_active() check to decided which top to use when
4134         // scanning cards (see CR 7039627).
4135         increment_gc_time_stamp();
4136 
4137         verify_after_gc();
4138 
4139         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4140         ref_processor_stw()->verify_no_references_recorded();
4141 
4142         // CM reference discovery will be re-enabled if necessary.
4143       }
4144 
4145       // We should do this after we potentially expand the heap so
4146       // that all the COMMIT events are generated before the end GC
4147       // event, and after we retire the GC alloc regions so that all
4148       // RETIRE events are generated before the end GC event.
4149       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4150 
4151       if (mark_in_progress()) {
4152         concurrent_mark()->update_g1_committed();
4153       }
4154 
4155 #ifdef TRACESPINNING
4156       ParallelTaskTerminator::print_termination_counts();
4157 #endif
4158 
4159       gc_epilogue(false);
4160     }
4161 
4162     // Print the remainder of the GC log output.
4163     log_gc_footer(os::elapsedTime() - pause_start_sec);
4164 
4165     // It is not yet to safe to tell the concurrent mark to
4166     // start as we have some optional output below. We don't want the
4167     // output from the concurrent mark thread interfering with this
4168     // logging output either.
4169 
4170     _hrs.verify_optional();
4171     verify_region_sets_optional();
4172 
4173     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4174     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4175 
4176     print_heap_after_gc();
4177 
4178     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4179     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4180     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4181     // before any GC notifications are raised.
4182     g1mm()->update_sizes();
4183   }
4184 
4185   // It should now be safe to tell the concurrent mark thread to start
4186   // without its logging output interfering with the logging output
4187   // that came from the pause.
4188 
4189   if (should_start_conc_mark) {
4190     // CAUTION: after the doConcurrentMark() call below,
4191     // the concurrent marking thread(s) could be running
4192     // concurrently with us. Make sure that anything after
4193     // this point does not assume that we are the only GC thread
4194     // running. Note: of course, the actual marking work will
4195     // not start until the safepoint itself is released in
4196     // ConcurrentGCThread::safepoint_desynchronize().
4197     doConcurrentMark();
4198   }
4199 
4200   return true;
4201 }
4202 
4203 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4204 {
4205   size_t gclab_word_size;
4206   switch (purpose) {
4207     case GCAllocForSurvived:
4208       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4209       break;
4210     case GCAllocForTenured:
4211       gclab_word_size = _old_plab_stats.desired_plab_sz();
4212       break;
4213     default:
4214       assert(false, "unknown GCAllocPurpose");
4215       gclab_word_size = _old_plab_stats.desired_plab_sz();
4216       break;
4217   }
4218 
4219   // Prevent humongous PLAB sizes for two reasons:
4220   // * PLABs are allocated using a similar paths as oops, but should
4221   //   never be in a humongous region
4222   // * Allowing humongous PLABs needlessly churns the region free lists
4223   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4224 }
4225 
4226 void G1CollectedHeap::init_mutator_alloc_region() {
4227   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4228   _mutator_alloc_region.init();
4229 }
4230 
4231 void G1CollectedHeap::release_mutator_alloc_region() {
4232   _mutator_alloc_region.release();
4233   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4234 }
4235 
4236 void G1CollectedHeap::init_gc_alloc_regions() {
4237   assert_at_safepoint(true /* should_be_vm_thread */);
4238 
4239   _survivor_gc_alloc_region.init();
4240   _old_gc_alloc_region.init();
4241   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4242   _retained_old_gc_alloc_region = NULL;
4243 
4244   // We will discard the current GC alloc region if:
4245   // a) it's in the collection set (it can happen!),
4246   // b) it's already full (no point in using it),
4247   // c) it's empty (this means that it was emptied during
4248   // a cleanup and it should be on the free list now), or
4249   // d) it's humongous (this means that it was emptied
4250   // during a cleanup and was added to the free list, but
4251   // has been subseqently used to allocate a humongous
4252   // object that may be less than the region size).
4253   if (retained_region != NULL &&
4254       !retained_region->in_collection_set() &&
4255       !(retained_region->top() == retained_region->end()) &&
4256       !retained_region->is_empty() &&
4257       !retained_region->isHumongous()) {
4258     retained_region->set_saved_mark();
4259     // The retained region was added to the old region set when it was
4260     // retired. We have to remove it now, since we don't allow regions
4261     // we allocate to in the region sets. We'll re-add it later, when
4262     // it's retired again.
4263     _old_set.remove(retained_region);
4264     bool during_im = g1_policy()->during_initial_mark_pause();
4265     retained_region->note_start_of_copying(during_im);
4266     _old_gc_alloc_region.set(retained_region);
4267     _hr_printer.reuse(retained_region);
4268   }
4269 }
4270 
4271 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers) {
4272   _survivor_gc_alloc_region.release();
4273   // If we have an old GC alloc region to release, we'll save it in
4274   // _retained_old_gc_alloc_region. If we don't
4275   // _retained_old_gc_alloc_region will become NULL. This is what we
4276   // want either way so no reason to check explicitly for either
4277   // condition.
4278   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4279 
4280   if (ResizePLAB) {
4281     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4282     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4283   }
4284 }
4285 
4286 void G1CollectedHeap::abandon_gc_alloc_regions() {
4287   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4288   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4289   _retained_old_gc_alloc_region = NULL;
4290 }
4291 
4292 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4293   _drain_in_progress = false;
4294   set_evac_failure_closure(cl);
4295   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4296 }
4297 
4298 void G1CollectedHeap::finalize_for_evac_failure() {
4299   assert(_evac_failure_scan_stack != NULL &&
4300          _evac_failure_scan_stack->length() == 0,
4301          "Postcondition");
4302   assert(!_drain_in_progress, "Postcondition");
4303   delete _evac_failure_scan_stack;
4304   _evac_failure_scan_stack = NULL;
4305 }
4306 
4307 void G1CollectedHeap::remove_self_forwarding_pointers() {
4308   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4309 
4310   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4311 
4312   if (G1CollectedHeap::use_parallel_gc_threads()) {
4313     set_par_threads();
4314     workers()->run_task(&rsfp_task);
4315     set_par_threads(0);
4316   } else {
4317     rsfp_task.work(0);
4318   }
4319 
4320   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4321 
4322   // Reset the claim values in the regions in the collection set.
4323   reset_cset_heap_region_claim_values();
4324 
4325   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4326 
4327   // Now restore saved marks, if any.
4328   assert(_objs_with_preserved_marks.size() ==
4329             _preserved_marks_of_objs.size(), "Both or none.");
4330   while (!_objs_with_preserved_marks.is_empty()) {
4331     oop obj = _objs_with_preserved_marks.pop();
4332     markOop m = _preserved_marks_of_objs.pop();
4333     obj->set_mark(m);
4334   }
4335   _objs_with_preserved_marks.clear(true);
4336   _preserved_marks_of_objs.clear(true);
4337 }
4338 
4339 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4340   _evac_failure_scan_stack->push(obj);
4341 }
4342 
4343 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4344   assert(_evac_failure_scan_stack != NULL, "precondition");
4345 
4346   while (_evac_failure_scan_stack->length() > 0) {
4347      oop obj = _evac_failure_scan_stack->pop();
4348      _evac_failure_closure->set_region(heap_region_containing(obj));
4349      obj->oop_iterate_backwards(_evac_failure_closure);
4350   }
4351 }
4352 
4353 oop
4354 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4355                                                oop old) {
4356   assert(obj_in_cs(old),
4357          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4358                  (HeapWord*) old));
4359   markOop m = old->mark();
4360   oop forward_ptr = old->forward_to_atomic(old);
4361   if (forward_ptr == NULL) {
4362     // Forward-to-self succeeded.
4363 
4364     if (_evac_failure_closure != cl) {
4365       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4366       assert(!_drain_in_progress,
4367              "Should only be true while someone holds the lock.");
4368       // Set the global evac-failure closure to the current thread's.
4369       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4370       set_evac_failure_closure(cl);
4371       // Now do the common part.
4372       handle_evacuation_failure_common(old, m);
4373       // Reset to NULL.
4374       set_evac_failure_closure(NULL);
4375     } else {
4376       // The lock is already held, and this is recursive.
4377       assert(_drain_in_progress, "This should only be the recursive case.");
4378       handle_evacuation_failure_common(old, m);
4379     }
4380     return old;
4381   } else {
4382     // Forward-to-self failed. Either someone else managed to allocate
4383     // space for this object (old != forward_ptr) or they beat us in
4384     // self-forwarding it (old == forward_ptr).
4385     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4386            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4387                    "should not be in the CSet",
4388                    (HeapWord*) old, (HeapWord*) forward_ptr));
4389     return forward_ptr;
4390   }
4391 }
4392 
4393 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4394   set_evacuation_failed(true);
4395 
4396   preserve_mark_if_necessary(old, m);
4397 
4398   HeapRegion* r = heap_region_containing(old);
4399   if (!r->evacuation_failed()) {
4400     r->set_evacuation_failed(true);
4401     _hr_printer.evac_failure(r);
4402   }
4403 
4404   push_on_evac_failure_scan_stack(old);
4405 
4406   if (!_drain_in_progress) {
4407     // prevent recursion in copy_to_survivor_space()
4408     _drain_in_progress = true;
4409     drain_evac_failure_scan_stack();
4410     _drain_in_progress = false;
4411   }
4412 }
4413 
4414 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4415   assert(evacuation_failed(), "Oversaving!");
4416   // We want to call the "for_promotion_failure" version only in the
4417   // case of a promotion failure.
4418   if (m->must_be_preserved_for_promotion_failure(obj)) {
4419     _objs_with_preserved_marks.push(obj);
4420     _preserved_marks_of_objs.push(m);
4421   }
4422 }
4423 
4424 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4425                                                   size_t word_size) {
4426   if (purpose == GCAllocForSurvived) {
4427     HeapWord* result = survivor_attempt_allocation(word_size);
4428     if (result != NULL) {
4429       return result;
4430     } else {
4431       // Let's try to allocate in the old gen in case we can fit the
4432       // object there.
4433       return old_attempt_allocation(word_size);
4434     }
4435   } else {
4436     assert(purpose ==  GCAllocForTenured, "sanity");
4437     HeapWord* result = old_attempt_allocation(word_size);
4438     if (result != NULL) {
4439       return result;
4440     } else {
4441       // Let's try to allocate in the survivors in case we can fit the
4442       // object there.
4443       return survivor_attempt_allocation(word_size);
4444     }
4445   }
4446 
4447   ShouldNotReachHere();
4448   // Trying to keep some compilers happy.
4449   return NULL;
4450 }
4451 
4452 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4453   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4454 
4455 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4456   : _g1h(g1h),
4457     _refs(g1h->task_queue(queue_num)),
4458     _dcq(&g1h->dirty_card_queue_set()),
4459     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4460     _g1_rem(g1h->g1_rem_set()),
4461     _hash_seed(17), _queue_num(queue_num),
4462     _term_attempts(0),
4463     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4464     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4465     _age_table(false),
4466     _strong_roots_time(0), _term_time(0),
4467     _alloc_buffer_waste(0), _undo_waste(0) {
4468   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4469   // we "sacrifice" entry 0 to keep track of surviving bytes for
4470   // non-young regions (where the age is -1)
4471   // We also add a few elements at the beginning and at the end in
4472   // an attempt to eliminate cache contention
4473   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4474   uint array_length = PADDING_ELEM_NUM +
4475                       real_length +
4476                       PADDING_ELEM_NUM;
4477   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4478   if (_surviving_young_words_base == NULL)
4479     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4480                           "Not enough space for young surv histo.");
4481   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4482   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4483 
4484   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4485   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4486 
4487   _start = os::elapsedTime();
4488 }
4489 
4490 void
4491 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4492 {
4493   st->print_raw_cr("GC Termination Stats");
4494   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4495                    " ------waste (KiB)------");
4496   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4497                    "  total   alloc    undo");
4498   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4499                    " ------- ------- -------");
4500 }
4501 
4502 void
4503 G1ParScanThreadState::print_termination_stats(int i,
4504                                               outputStream* const st) const
4505 {
4506   const double elapsed_ms = elapsed_time() * 1000.0;
4507   const double s_roots_ms = strong_roots_time() * 1000.0;
4508   const double term_ms    = term_time() * 1000.0;
4509   st->print_cr("%3d %9.2f %9.2f %6.2f "
4510                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4511                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4512                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4513                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4514                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4515                alloc_buffer_waste() * HeapWordSize / K,
4516                undo_waste() * HeapWordSize / K);
4517 }
4518 
4519 #ifdef ASSERT
4520 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4521   assert(ref != NULL, "invariant");
4522   assert(UseCompressedOops, "sanity");
4523   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4524   oop p = oopDesc::load_decode_heap_oop(ref);
4525   assert(_g1h->is_in_g1_reserved(p),
4526          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4527   return true;
4528 }
4529 
4530 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4531   assert(ref != NULL, "invariant");
4532   if (has_partial_array_mask(ref)) {
4533     // Must be in the collection set--it's already been copied.
4534     oop p = clear_partial_array_mask(ref);
4535     assert(_g1h->obj_in_cs(p),
4536            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4537   } else {
4538     oop p = oopDesc::load_decode_heap_oop(ref);
4539     assert(_g1h->is_in_g1_reserved(p),
4540            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4541   }
4542   return true;
4543 }
4544 
4545 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4546   if (ref.is_narrow()) {
4547     return verify_ref((narrowOop*) ref);
4548   } else {
4549     return verify_ref((oop*) ref);
4550   }
4551 }
4552 #endif // ASSERT
4553 
4554 void G1ParScanThreadState::trim_queue() {
4555   assert(_evac_cl != NULL, "not set");
4556   assert(_evac_failure_cl != NULL, "not set");
4557   assert(_partial_scan_cl != NULL, "not set");
4558 
4559   StarTask ref;
4560   do {
4561     // Drain the overflow stack first, so other threads can steal.
4562     while (refs()->pop_overflow(ref)) {
4563       deal_with_reference(ref);
4564     }
4565 
4566     while (refs()->pop_local(ref)) {
4567       deal_with_reference(ref);
4568     }
4569   } while (!refs()->is_empty());
4570 }
4571 
4572 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4573                                      G1ParScanThreadState* par_scan_state) :
4574   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4575   _par_scan_state(par_scan_state),
4576   _worker_id(par_scan_state->queue_num()),
4577   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4578   _mark_in_progress(_g1->mark_in_progress()) { }
4579 
4580 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4581 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4582 #ifdef ASSERT
4583   HeapRegion* hr = _g1->heap_region_containing(obj);
4584   assert(hr != NULL, "sanity");
4585   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4586 #endif // ASSERT
4587 
4588   // We know that the object is not moving so it's safe to read its size.
4589   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4590 }
4591 
4592 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4593 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4594   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4595 #ifdef ASSERT
4596   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4597   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4598   assert(from_obj != to_obj, "should not be self-forwarded");
4599 
4600   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4601   assert(from_hr != NULL, "sanity");
4602   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4603 
4604   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4605   assert(to_hr != NULL, "sanity");
4606   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4607 #endif // ASSERT
4608 
4609   // The object might be in the process of being copied by another
4610   // worker so we cannot trust that its to-space image is
4611   // well-formed. So we have to read its size from its from-space
4612   // image which we know should not be changing.
4613   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4614 }
4615 
4616 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4617 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4618   ::copy_to_survivor_space(oop old) {
4619   size_t word_sz = old->size();
4620   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4621   // +1 to make the -1 indexes valid...
4622   int       young_index = from_region->young_index_in_cset()+1;
4623   assert( (from_region->is_young() && young_index >  0) ||
4624          (!from_region->is_young() && young_index == 0), "invariant" );
4625   G1CollectorPolicy* g1p = _g1->g1_policy();
4626   markOop m = old->mark();
4627   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4628                                            : m->age();
4629   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4630                                                              word_sz);
4631   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4632 #ifndef PRODUCT
4633   // Should this evacuation fail?
4634   if (_g1->evacuation_should_fail()) {
4635     if (obj_ptr != NULL) {
4636       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4637       obj_ptr = NULL;
4638     }
4639   }
4640 #endif // !PRODUCT
4641 
4642   if (obj_ptr == NULL) {
4643     // This will either forward-to-self, or detect that someone else has
4644     // installed a forwarding pointer.
4645     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4646     return _g1->handle_evacuation_failure_par(cl, old);
4647   }
4648 
4649   oop obj = oop(obj_ptr);
4650 
4651   // We're going to allocate linearly, so might as well prefetch ahead.
4652   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4653 
4654   oop forward_ptr = old->forward_to_atomic(obj);
4655   if (forward_ptr == NULL) {
4656     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4657     if (g1p->track_object_age(alloc_purpose)) {
4658       // We could simply do obj->incr_age(). However, this causes a
4659       // performance issue. obj->incr_age() will first check whether
4660       // the object has a displaced mark by checking its mark word;
4661       // getting the mark word from the new location of the object
4662       // stalls. So, given that we already have the mark word and we
4663       // are about to install it anyway, it's better to increase the
4664       // age on the mark word, when the object does not have a
4665       // displaced mark word. We're not expecting many objects to have
4666       // a displaced marked word, so that case is not optimized
4667       // further (it could be...) and we simply call obj->incr_age().
4668 
4669       if (m->has_displaced_mark_helper()) {
4670         // in this case, we have to install the mark word first,
4671         // otherwise obj looks to be forwarded (the old mark word,
4672         // which contains the forward pointer, was copied)
4673         obj->set_mark(m);
4674         obj->incr_age();
4675       } else {
4676         m = m->incr_age();
4677         obj->set_mark(m);
4678       }
4679       _par_scan_state->age_table()->add(obj, word_sz);
4680     } else {
4681       obj->set_mark(m);
4682     }
4683 
4684     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4685     surv_young_words[young_index] += word_sz;
4686 
4687     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4688       // We keep track of the next start index in the length field of
4689       // the to-space object. The actual length can be found in the
4690       // length field of the from-space object.
4691       arrayOop(obj)->set_length(0);
4692       oop* old_p = set_partial_array_mask(old);
4693       _par_scan_state->push_on_queue(old_p);
4694     } else {
4695       // No point in using the slower heap_region_containing() method,
4696       // given that we know obj is in the heap.
4697       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4698       obj->oop_iterate_backwards(&_scanner);
4699     }
4700   } else {
4701     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4702     obj = forward_ptr;
4703   }
4704   return obj;
4705 }
4706 
4707 template <class T>
4708 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4709   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4710     _scanned_klass->record_modified_oops();
4711   }
4712 }
4713 
4714 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4715 template <class T>
4716 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4717 ::do_oop_work(T* p) {
4718   oop obj = oopDesc::load_decode_heap_oop(p);
4719   assert(barrier != G1BarrierRS || obj != NULL,
4720          "Precondition: G1BarrierRS implies obj is non-NULL");
4721 
4722   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4723 
4724   // here the null check is implicit in the cset_fast_test() test
4725   if (_g1->in_cset_fast_test(obj)) {
4726     oop forwardee;
4727     if (obj->is_forwarded()) {
4728       forwardee = obj->forwardee();
4729     } else {
4730       forwardee = copy_to_survivor_space(obj);
4731     }
4732     assert(forwardee != NULL, "forwardee should not be NULL");
4733     oopDesc::encode_store_heap_oop(p, forwardee);
4734     if (do_mark_object && forwardee != obj) {
4735       // If the object is self-forwarded we don't need to explicitly
4736       // mark it, the evacuation failure protocol will do so.
4737       mark_forwarded_object(obj, forwardee);
4738     }
4739 
4740     // When scanning the RS, we only care about objs in CS.
4741     if (barrier == G1BarrierRS) {
4742       _par_scan_state->update_rs(_from, p, _worker_id);
4743     } else if (barrier == G1BarrierKlass) {
4744       do_klass_barrier(p, forwardee);
4745     }
4746   } else {
4747     // The object is not in collection set. If we're a root scanning
4748     // closure during an initial mark pause (i.e. do_mark_object will
4749     // be true) then attempt to mark the object.
4750     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4751       mark_object(obj);
4752     }
4753   }
4754 
4755   if (barrier == G1BarrierEvac && obj != NULL) {
4756     _par_scan_state->update_rs(_from, p, _worker_id);
4757   }
4758 
4759   if (do_gen_barrier && obj != NULL) {
4760     par_do_barrier(p);
4761   }
4762 }
4763 
4764 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4765 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4766 
4767 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4768   assert(has_partial_array_mask(p), "invariant");
4769   oop from_obj = clear_partial_array_mask(p);
4770 
4771   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4772   assert(from_obj->is_objArray(), "must be obj array");
4773   objArrayOop from_obj_array = objArrayOop(from_obj);
4774   // The from-space object contains the real length.
4775   int length                 = from_obj_array->length();
4776 
4777   assert(from_obj->is_forwarded(), "must be forwarded");
4778   oop to_obj                 = from_obj->forwardee();
4779   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4780   objArrayOop to_obj_array   = objArrayOop(to_obj);
4781   // We keep track of the next start index in the length field of the
4782   // to-space object.
4783   int next_index             = to_obj_array->length();
4784   assert(0 <= next_index && next_index < length,
4785          err_msg("invariant, next index: %d, length: %d", next_index, length));
4786 
4787   int start                  = next_index;
4788   int end                    = length;
4789   int remainder              = end - start;
4790   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4791   if (remainder > 2 * ParGCArrayScanChunk) {
4792     end = start + ParGCArrayScanChunk;
4793     to_obj_array->set_length(end);
4794     // Push the remainder before we process the range in case another
4795     // worker has run out of things to do and can steal it.
4796     oop* from_obj_p = set_partial_array_mask(from_obj);
4797     _par_scan_state->push_on_queue(from_obj_p);
4798   } else {
4799     assert(length == end, "sanity");
4800     // We'll process the final range for this object. Restore the length
4801     // so that the heap remains parsable in case of evacuation failure.
4802     to_obj_array->set_length(end);
4803   }
4804   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4805   // Process indexes [start,end). It will also process the header
4806   // along with the first chunk (i.e., the chunk with start == 0).
4807   // Note that at this point the length field of to_obj_array is not
4808   // correct given that we are using it to keep track of the next
4809   // start index. oop_iterate_range() (thankfully!) ignores the length
4810   // field and only relies on the start / end parameters.  It does
4811   // however return the size of the object which will be incorrect. So
4812   // we have to ignore it even if we wanted to use it.
4813   to_obj_array->oop_iterate_range(&_scanner, start, end);
4814 }
4815 
4816 class G1ParEvacuateFollowersClosure : public VoidClosure {
4817 protected:
4818   G1CollectedHeap*              _g1h;
4819   G1ParScanThreadState*         _par_scan_state;
4820   RefToScanQueueSet*            _queues;
4821   ParallelTaskTerminator*       _terminator;
4822 
4823   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4824   RefToScanQueueSet*      queues()         { return _queues; }
4825   ParallelTaskTerminator* terminator()     { return _terminator; }
4826 
4827 public:
4828   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4829                                 G1ParScanThreadState* par_scan_state,
4830                                 RefToScanQueueSet* queues,
4831                                 ParallelTaskTerminator* terminator)
4832     : _g1h(g1h), _par_scan_state(par_scan_state),
4833       _queues(queues), _terminator(terminator) {}
4834 
4835   void do_void();
4836 
4837 private:
4838   inline bool offer_termination();
4839 };
4840 
4841 bool G1ParEvacuateFollowersClosure::offer_termination() {
4842   G1ParScanThreadState* const pss = par_scan_state();
4843   pss->start_term_time();
4844   const bool res = terminator()->offer_termination();
4845   pss->end_term_time();
4846   return res;
4847 }
4848 
4849 void G1ParEvacuateFollowersClosure::do_void() {
4850   StarTask stolen_task;
4851   G1ParScanThreadState* const pss = par_scan_state();
4852   pss->trim_queue();
4853 
4854   do {
4855     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4856       assert(pss->verify_task(stolen_task), "sanity");
4857       if (stolen_task.is_narrow()) {
4858         pss->deal_with_reference((narrowOop*) stolen_task);
4859       } else {
4860         pss->deal_with_reference((oop*) stolen_task);
4861       }
4862 
4863       // We've just processed a reference and we might have made
4864       // available new entries on the queues. So we have to make sure
4865       // we drain the queues as necessary.
4866       pss->trim_queue();
4867     }
4868   } while (!offer_termination());
4869 
4870   pss->retire_alloc_buffers();
4871 }
4872 
4873 class G1KlassScanClosure : public KlassClosure {
4874  G1ParCopyHelper* _closure;
4875  bool             _process_only_dirty;
4876  int              _count;
4877  public:
4878   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4879       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4880   void do_klass(Klass* klass) {
4881     // If the klass has not been dirtied we know that there's
4882     // no references into  the young gen and we can skip it.
4883    if (!_process_only_dirty || klass->has_modified_oops()) {
4884       // Clean the klass since we're going to scavenge all the metadata.
4885       klass->clear_modified_oops();
4886 
4887       // Tell the closure that this klass is the Klass to scavenge
4888       // and is the one to dirty if oops are left pointing into the young gen.
4889       _closure->set_scanned_klass(klass);
4890 
4891       klass->oops_do(_closure);
4892 
4893       _closure->set_scanned_klass(NULL);
4894     }
4895     _count++;
4896   }
4897 };
4898 
4899 class G1ParTask : public AbstractGangTask {
4900 protected:
4901   G1CollectedHeap*       _g1h;
4902   RefToScanQueueSet      *_queues;
4903   ParallelTaskTerminator _terminator;
4904   uint _n_workers;
4905 
4906   Mutex _stats_lock;
4907   Mutex* stats_lock() { return &_stats_lock; }
4908 
4909   size_t getNCards() {
4910     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4911       / G1BlockOffsetSharedArray::N_bytes;
4912   }
4913 
4914 public:
4915   G1ParTask(G1CollectedHeap* g1h,
4916             RefToScanQueueSet *task_queues)
4917     : AbstractGangTask("G1 collection"),
4918       _g1h(g1h),
4919       _queues(task_queues),
4920       _terminator(0, _queues),
4921       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4922   {}
4923 
4924   RefToScanQueueSet* queues() { return _queues; }
4925 
4926   RefToScanQueue *work_queue(int i) {
4927     return queues()->queue(i);
4928   }
4929 
4930   ParallelTaskTerminator* terminator() { return &_terminator; }
4931 
4932   virtual void set_for_termination(int active_workers) {
4933     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4934     // in the young space (_par_seq_tasks) in the G1 heap
4935     // for SequentialSubTasksDone.
4936     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4937     // both of which need setting by set_n_termination().
4938     _g1h->SharedHeap::set_n_termination(active_workers);
4939     _g1h->set_n_termination(active_workers);
4940     terminator()->reset_for_reuse(active_workers);
4941     _n_workers = active_workers;
4942   }
4943 
4944   void work(uint worker_id) {
4945     if (worker_id >= _n_workers) return;  // no work needed this round
4946 
4947     double start_time_ms = os::elapsedTime() * 1000.0;
4948     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4949 
4950     {
4951       ResourceMark rm;
4952       HandleMark   hm;
4953 
4954       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4955 
4956       G1ParScanThreadState            pss(_g1h, worker_id);
4957       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
4958       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4959       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
4960 
4961       pss.set_evac_closure(&scan_evac_cl);
4962       pss.set_evac_failure_closure(&evac_failure_cl);
4963       pss.set_partial_scan_closure(&partial_scan_cl);
4964 
4965       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4966       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
4967 
4968       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4969       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4970 
4971       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
4972       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4973       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4974 
4975       OopClosure*                    scan_root_cl = &only_scan_root_cl;
4976       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
4977 
4978       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4979         // We also need to mark copied objects.
4980         scan_root_cl = &scan_mark_root_cl;
4981         scan_klasses_cl = &scan_mark_klasses_cl_s;
4982       }
4983 
4984       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
4985 
4986       // Don't scan the scavengable methods in the code cache as part
4987       // of strong root scanning. The code roots that point into a 
4988       // region in the collection set are scanned when we scan the
4989       // region's RSet.
4990       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
4991 
4992       pss.start_strong_roots();
4993       _g1h->g1_process_strong_roots(/* is scavenging */ true,
4994                                     SharedHeap::ScanningOption(so),
4995                                     scan_root_cl,
4996                                     &push_heap_rs_cl,
4997                                     scan_klasses_cl,
4998                                     worker_id);
4999       pss.end_strong_roots();
5000 
5001       {
5002         double start = os::elapsedTime();
5003         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5004         evac.do_void();
5005         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5006         double term_ms = pss.term_time()*1000.0;
5007         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5008         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5009       }
5010       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5011       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5012 
5013       if (ParallelGCVerbose) {
5014         MutexLocker x(stats_lock());
5015         pss.print_termination_stats(worker_id);
5016       }
5017 
5018       assert(pss.refs()->is_empty(), "should be empty");
5019 
5020       // Close the inner scope so that the ResourceMark and HandleMark
5021       // destructors are executed here and are included as part of the
5022       // "GC Worker Time".
5023     }
5024 
5025     double end_time_ms = os::elapsedTime() * 1000.0;
5026     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5027   }
5028 };
5029 
5030 // *** Common G1 Evacuation Stuff
5031 
5032 // This method is run in a GC worker.
5033 
5034 void
5035 G1CollectedHeap::
5036 g1_process_strong_roots(bool is_scavenging,
5037                         ScanningOption so,
5038                         OopClosure* scan_non_heap_roots,
5039                         OopsInHeapRegionClosure* scan_rs,
5040                         G1KlassScanClosure* scan_klasses,
5041                         int worker_i) {
5042 
5043   // First scan the strong roots
5044   double ext_roots_start = os::elapsedTime();
5045   double closure_app_time_sec = 0.0;
5046 
5047   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5048 
5049   assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5050   // Walk the code cache/strong code roots w/o buffering, because StarTask
5051   // cannot handle unaligned oop locations.
5052   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5053 
5054   process_strong_roots(false, // no scoping; this is parallel code
5055                        is_scavenging, so,
5056                        &buf_scan_non_heap_roots,
5057                        &eager_scan_code_roots,
5058                        scan_klasses
5059                        );
5060 
5061   // Now the CM ref_processor roots.
5062   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5063     // We need to treat the discovered reference lists of the
5064     // concurrent mark ref processor as roots and keep entries
5065     // (which are added by the marking threads) on them live
5066     // until they can be processed at the end of marking.
5067     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5068   }
5069 
5070   // Finish up any enqueued closure apps (attributed as object copy time).
5071   buf_scan_non_heap_roots.done();
5072 
5073   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5074 
5075   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5076 
5077   double ext_root_time_ms =
5078     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5079 
5080   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5081 
5082   // During conc marking we have to filter the per-thread SATB buffers
5083   // to make sure we remove any oops into the CSet (which will show up
5084   // as implicitly live).
5085   double satb_filtering_ms = 0.0;
5086   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5087     if (mark_in_progress()) {
5088       double satb_filter_start = os::elapsedTime();
5089 
5090       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5091 
5092       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5093     }
5094   }
5095   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5096 
5097   // If this is an initial mark pause, and we're not scanning
5098   // the entire code cache, we need to mark the oops in the
5099   // strong code root lists for the regions that are not in
5100   // the collection set. 
5101   // Note all threads participate in this set of root tasks.
5102   double mark_strong_code_roots_ms = 0.0;
5103   if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5104     double mark_strong_roots_start = os::elapsedTime();
5105     mark_strong_code_roots(worker_i);
5106     mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5107   }
5108   g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5109 
5110   // Now scan the complement of the collection set.
5111   if (scan_rs != NULL) {
5112     g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5113   }
5114   _process_strong_tasks->all_tasks_completed();
5115 }
5116 
5117 void
5118 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5119   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5120   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5121 }
5122 
5123 // Weak Reference Processing support
5124 
5125 // An always "is_alive" closure that is used to preserve referents.
5126 // If the object is non-null then it's alive.  Used in the preservation
5127 // of referent objects that are pointed to by reference objects
5128 // discovered by the CM ref processor.
5129 class G1AlwaysAliveClosure: public BoolObjectClosure {
5130   G1CollectedHeap* _g1;
5131 public:
5132   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5133   bool do_object_b(oop p) {
5134     if (p != NULL) {
5135       return true;
5136     }
5137     return false;
5138   }
5139 };
5140 
5141 bool G1STWIsAliveClosure::do_object_b(oop p) {
5142   // An object is reachable if it is outside the collection set,
5143   // or is inside and copied.
5144   return !_g1->obj_in_cs(p) || p->is_forwarded();
5145 }
5146 
5147 // Non Copying Keep Alive closure
5148 class G1KeepAliveClosure: public OopClosure {
5149   G1CollectedHeap* _g1;
5150 public:
5151   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5152   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5153   void do_oop(      oop* p) {
5154     oop obj = *p;
5155 
5156     if (_g1->obj_in_cs(obj)) {
5157       assert( obj->is_forwarded(), "invariant" );
5158       *p = obj->forwardee();
5159     }
5160   }
5161 };
5162 
5163 // Copying Keep Alive closure - can be called from both
5164 // serial and parallel code as long as different worker
5165 // threads utilize different G1ParScanThreadState instances
5166 // and different queues.
5167 
5168 class G1CopyingKeepAliveClosure: public OopClosure {
5169   G1CollectedHeap*         _g1h;
5170   OopClosure*              _copy_non_heap_obj_cl;
5171   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5172   G1ParScanThreadState*    _par_scan_state;
5173 
5174 public:
5175   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5176                             OopClosure* non_heap_obj_cl,
5177                             OopsInHeapRegionClosure* metadata_obj_cl,
5178                             G1ParScanThreadState* pss):
5179     _g1h(g1h),
5180     _copy_non_heap_obj_cl(non_heap_obj_cl),
5181     _copy_metadata_obj_cl(metadata_obj_cl),
5182     _par_scan_state(pss)
5183   {}
5184 
5185   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5186   virtual void do_oop(      oop* p) { do_oop_work(p); }
5187 
5188   template <class T> void do_oop_work(T* p) {
5189     oop obj = oopDesc::load_decode_heap_oop(p);
5190 
5191     if (_g1h->obj_in_cs(obj)) {
5192       // If the referent object has been forwarded (either copied
5193       // to a new location or to itself in the event of an
5194       // evacuation failure) then we need to update the reference
5195       // field and, if both reference and referent are in the G1
5196       // heap, update the RSet for the referent.
5197       //
5198       // If the referent has not been forwarded then we have to keep
5199       // it alive by policy. Therefore we have copy the referent.
5200       //
5201       // If the reference field is in the G1 heap then we can push
5202       // on the PSS queue. When the queue is drained (after each
5203       // phase of reference processing) the object and it's followers
5204       // will be copied, the reference field set to point to the
5205       // new location, and the RSet updated. Otherwise we need to
5206       // use the the non-heap or metadata closures directly to copy
5207       // the refernt object and update the pointer, while avoiding
5208       // updating the RSet.
5209 
5210       if (_g1h->is_in_g1_reserved(p)) {
5211         _par_scan_state->push_on_queue(p);
5212       } else {
5213         assert(!ClassLoaderDataGraph::contains((address)p),
5214                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5215                               PTR_FORMAT, p));
5216           _copy_non_heap_obj_cl->do_oop(p);
5217         }
5218       }
5219     }
5220 };
5221 
5222 // Serial drain queue closure. Called as the 'complete_gc'
5223 // closure for each discovered list in some of the
5224 // reference processing phases.
5225 
5226 class G1STWDrainQueueClosure: public VoidClosure {
5227 protected:
5228   G1CollectedHeap* _g1h;
5229   G1ParScanThreadState* _par_scan_state;
5230 
5231   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5232 
5233 public:
5234   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5235     _g1h(g1h),
5236     _par_scan_state(pss)
5237   { }
5238 
5239   void do_void() {
5240     G1ParScanThreadState* const pss = par_scan_state();
5241     pss->trim_queue();
5242   }
5243 };
5244 
5245 // Parallel Reference Processing closures
5246 
5247 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5248 // processing during G1 evacuation pauses.
5249 
5250 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5251 private:
5252   G1CollectedHeap*   _g1h;
5253   RefToScanQueueSet* _queues;
5254   FlexibleWorkGang*  _workers;
5255   int                _active_workers;
5256 
5257 public:
5258   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5259                         FlexibleWorkGang* workers,
5260                         RefToScanQueueSet *task_queues,
5261                         int n_workers) :
5262     _g1h(g1h),
5263     _queues(task_queues),
5264     _workers(workers),
5265     _active_workers(n_workers)
5266   {
5267     assert(n_workers > 0, "shouldn't call this otherwise");
5268   }
5269 
5270   // Executes the given task using concurrent marking worker threads.
5271   virtual void execute(ProcessTask& task);
5272   virtual void execute(EnqueueTask& task);
5273 };
5274 
5275 // Gang task for possibly parallel reference processing
5276 
5277 class G1STWRefProcTaskProxy: public AbstractGangTask {
5278   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5279   ProcessTask&     _proc_task;
5280   G1CollectedHeap* _g1h;
5281   RefToScanQueueSet *_task_queues;
5282   ParallelTaskTerminator* _terminator;
5283 
5284 public:
5285   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5286                      G1CollectedHeap* g1h,
5287                      RefToScanQueueSet *task_queues,
5288                      ParallelTaskTerminator* terminator) :
5289     AbstractGangTask("Process reference objects in parallel"),
5290     _proc_task(proc_task),
5291     _g1h(g1h),
5292     _task_queues(task_queues),
5293     _terminator(terminator)
5294   {}
5295 
5296   virtual void work(uint worker_id) {
5297     // The reference processing task executed by a single worker.
5298     ResourceMark rm;
5299     HandleMark   hm;
5300 
5301     G1STWIsAliveClosure is_alive(_g1h);
5302 
5303     G1ParScanThreadState pss(_g1h, worker_id);
5304 
5305     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5306     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5307     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5308 
5309     pss.set_evac_closure(&scan_evac_cl);
5310     pss.set_evac_failure_closure(&evac_failure_cl);
5311     pss.set_partial_scan_closure(&partial_scan_cl);
5312 
5313     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5314     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5315 
5316     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5317     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5318 
5319     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5320     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5321 
5322     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5323       // We also need to mark copied objects.
5324       copy_non_heap_cl = &copy_mark_non_heap_cl;
5325       copy_metadata_cl = &copy_mark_metadata_cl;
5326     }
5327 
5328     // Keep alive closure.
5329     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5330 
5331     // Complete GC closure
5332     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5333 
5334     // Call the reference processing task's work routine.
5335     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5336 
5337     // Note we cannot assert that the refs array is empty here as not all
5338     // of the processing tasks (specifically phase2 - pp2_work) execute
5339     // the complete_gc closure (which ordinarily would drain the queue) so
5340     // the queue may not be empty.
5341   }
5342 };
5343 
5344 // Driver routine for parallel reference processing.
5345 // Creates an instance of the ref processing gang
5346 // task and has the worker threads execute it.
5347 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5348   assert(_workers != NULL, "Need parallel worker threads.");
5349 
5350   ParallelTaskTerminator terminator(_active_workers, _queues);
5351   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5352 
5353   _g1h->set_par_threads(_active_workers);
5354   _workers->run_task(&proc_task_proxy);
5355   _g1h->set_par_threads(0);
5356 }
5357 
5358 // Gang task for parallel reference enqueueing.
5359 
5360 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5361   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5362   EnqueueTask& _enq_task;
5363 
5364 public:
5365   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5366     AbstractGangTask("Enqueue reference objects in parallel"),
5367     _enq_task(enq_task)
5368   { }
5369 
5370   virtual void work(uint worker_id) {
5371     _enq_task.work(worker_id);
5372   }
5373 };
5374 
5375 // Driver routine for parallel reference enqueing.
5376 // Creates an instance of the ref enqueueing gang
5377 // task and has the worker threads execute it.
5378 
5379 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5380   assert(_workers != NULL, "Need parallel worker threads.");
5381 
5382   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5383 
5384   _g1h->set_par_threads(_active_workers);
5385   _workers->run_task(&enq_task_proxy);
5386   _g1h->set_par_threads(0);
5387 }
5388 
5389 // End of weak reference support closures
5390 
5391 // Abstract task used to preserve (i.e. copy) any referent objects
5392 // that are in the collection set and are pointed to by reference
5393 // objects discovered by the CM ref processor.
5394 
5395 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5396 protected:
5397   G1CollectedHeap* _g1h;
5398   RefToScanQueueSet      *_queues;
5399   ParallelTaskTerminator _terminator;
5400   uint _n_workers;
5401 
5402 public:
5403   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5404     AbstractGangTask("ParPreserveCMReferents"),
5405     _g1h(g1h),
5406     _queues(task_queues),
5407     _terminator(workers, _queues),
5408     _n_workers(workers)
5409   { }
5410 
5411   void work(uint worker_id) {
5412     ResourceMark rm;
5413     HandleMark   hm;
5414 
5415     G1ParScanThreadState            pss(_g1h, worker_id);
5416     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5417     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5418     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5419 
5420     pss.set_evac_closure(&scan_evac_cl);
5421     pss.set_evac_failure_closure(&evac_failure_cl);
5422     pss.set_partial_scan_closure(&partial_scan_cl);
5423 
5424     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5425 
5426 
5427     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5428     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5429 
5430     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5431     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5432 
5433     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5434     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5435 
5436     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5437       // We also need to mark copied objects.
5438       copy_non_heap_cl = &copy_mark_non_heap_cl;
5439       copy_metadata_cl = &copy_mark_metadata_cl;
5440     }
5441 
5442     // Is alive closure
5443     G1AlwaysAliveClosure always_alive(_g1h);
5444 
5445     // Copying keep alive closure. Applied to referent objects that need
5446     // to be copied.
5447     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5448 
5449     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5450 
5451     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5452     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5453 
5454     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5455     // So this must be true - but assert just in case someone decides to
5456     // change the worker ids.
5457     assert(0 <= worker_id && worker_id < limit, "sanity");
5458     assert(!rp->discovery_is_atomic(), "check this code");
5459 
5460     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5461     for (uint idx = worker_id; idx < limit; idx += stride) {
5462       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5463 
5464       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5465       while (iter.has_next()) {
5466         // Since discovery is not atomic for the CM ref processor, we
5467         // can see some null referent objects.
5468         iter.load_ptrs(DEBUG_ONLY(true));
5469         oop ref = iter.obj();
5470 
5471         // This will filter nulls.
5472         if (iter.is_referent_alive()) {
5473           iter.make_referent_alive();
5474         }
5475         iter.move_to_next();
5476       }
5477     }
5478 
5479     // Drain the queue - which may cause stealing
5480     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5481     drain_queue.do_void();
5482     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5483     assert(pss.refs()->is_empty(), "should be");
5484   }
5485 };
5486 
5487 // Weak Reference processing during an evacuation pause (part 1).
5488 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5489   double ref_proc_start = os::elapsedTime();
5490 
5491   ReferenceProcessor* rp = _ref_processor_stw;
5492   assert(rp->discovery_enabled(), "should have been enabled");
5493 
5494   // Any reference objects, in the collection set, that were 'discovered'
5495   // by the CM ref processor should have already been copied (either by
5496   // applying the external root copy closure to the discovered lists, or
5497   // by following an RSet entry).
5498   //
5499   // But some of the referents, that are in the collection set, that these
5500   // reference objects point to may not have been copied: the STW ref
5501   // processor would have seen that the reference object had already
5502   // been 'discovered' and would have skipped discovering the reference,
5503   // but would not have treated the reference object as a regular oop.
5504   // As a reult the copy closure would not have been applied to the
5505   // referent object.
5506   //
5507   // We need to explicitly copy these referent objects - the references
5508   // will be processed at the end of remarking.
5509   //
5510   // We also need to do this copying before we process the reference
5511   // objects discovered by the STW ref processor in case one of these
5512   // referents points to another object which is also referenced by an
5513   // object discovered by the STW ref processor.
5514 
5515   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5516            no_of_gc_workers == workers()->active_workers(),
5517            "Need to reset active GC workers");
5518 
5519   set_par_threads(no_of_gc_workers);
5520   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5521                                                  no_of_gc_workers,
5522                                                  _task_queues);
5523 
5524   if (G1CollectedHeap::use_parallel_gc_threads()) {
5525     workers()->run_task(&keep_cm_referents);
5526   } else {
5527     keep_cm_referents.work(0);
5528   }
5529 
5530   set_par_threads(0);
5531 
5532   // Closure to test whether a referent is alive.
5533   G1STWIsAliveClosure is_alive(this);
5534 
5535   // Even when parallel reference processing is enabled, the processing
5536   // of JNI refs is serial and performed serially by the current thread
5537   // rather than by a worker. The following PSS will be used for processing
5538   // JNI refs.
5539 
5540   // Use only a single queue for this PSS.
5541   G1ParScanThreadState pss(this, 0);
5542 
5543   // We do not embed a reference processor in the copying/scanning
5544   // closures while we're actually processing the discovered
5545   // reference objects.
5546   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5547   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5548   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5549 
5550   pss.set_evac_closure(&scan_evac_cl);
5551   pss.set_evac_failure_closure(&evac_failure_cl);
5552   pss.set_partial_scan_closure(&partial_scan_cl);
5553 
5554   assert(pss.refs()->is_empty(), "pre-condition");
5555 
5556   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5557   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5558 
5559   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5560   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5561 
5562   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5563   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5564 
5565   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5566     // We also need to mark copied objects.
5567     copy_non_heap_cl = &copy_mark_non_heap_cl;
5568     copy_metadata_cl = &copy_mark_metadata_cl;
5569   }
5570 
5571   // Keep alive closure.
5572   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5573 
5574   // Serial Complete GC closure
5575   G1STWDrainQueueClosure drain_queue(this, &pss);
5576 
5577   // Setup the soft refs policy...
5578   rp->setup_policy(false);
5579 
5580   if (!rp->processing_is_mt()) {
5581     // Serial reference processing...
5582     rp->process_discovered_references(&is_alive,
5583                                       &keep_alive,
5584                                       &drain_queue,
5585                                       NULL);
5586   } else {
5587     // Parallel reference processing
5588     assert(rp->num_q() == no_of_gc_workers, "sanity");
5589     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5590 
5591     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5592     rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5593   }
5594 
5595   // We have completed copying any necessary live referent objects
5596   // (that were not copied during the actual pause) so we can
5597   // retire any active alloc buffers
5598   pss.retire_alloc_buffers();
5599   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5600 
5601   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5602   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5603 }
5604 
5605 // Weak Reference processing during an evacuation pause (part 2).
5606 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5607   double ref_enq_start = os::elapsedTime();
5608 
5609   ReferenceProcessor* rp = _ref_processor_stw;
5610   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5611 
5612   // Now enqueue any remaining on the discovered lists on to
5613   // the pending list.
5614   if (!rp->processing_is_mt()) {
5615     // Serial reference processing...
5616     rp->enqueue_discovered_references();
5617   } else {
5618     // Parallel reference enqueuing
5619 
5620     assert(no_of_gc_workers == workers()->active_workers(),
5621            "Need to reset active workers");
5622     assert(rp->num_q() == no_of_gc_workers, "sanity");
5623     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5624 
5625     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5626     rp->enqueue_discovered_references(&par_task_executor);
5627   }
5628 
5629   rp->verify_no_references_recorded();
5630   assert(!rp->discovery_enabled(), "should have been disabled");
5631 
5632   // FIXME
5633   // CM's reference processing also cleans up the string and symbol tables.
5634   // Should we do that here also? We could, but it is a serial operation
5635   // and could signicantly increase the pause time.
5636 
5637   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5638   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5639 }
5640 
5641 void G1CollectedHeap::evacuate_collection_set() {
5642   _expand_heap_after_alloc_failure = true;
5643   set_evacuation_failed(false);
5644 
5645   // Should G1EvacuationFailureALot be in effect for this GC?
5646   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5647 
5648   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5649 
5650   // Disable the hot card cache.
5651   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5652   hot_card_cache->reset_hot_cache_claimed_index();
5653   hot_card_cache->set_use_cache(false);
5654 
5655   uint n_workers;
5656   if (G1CollectedHeap::use_parallel_gc_threads()) {
5657     n_workers =
5658       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5659                                      workers()->active_workers(),
5660                                      Threads::number_of_non_daemon_threads());
5661     assert(UseDynamicNumberOfGCThreads ||
5662            n_workers == workers()->total_workers(),
5663            "If not dynamic should be using all the  workers");
5664     workers()->set_active_workers(n_workers);
5665     set_par_threads(n_workers);
5666   } else {
5667     assert(n_par_threads() == 0,
5668            "Should be the original non-parallel value");
5669     n_workers = 1;
5670   }
5671 
5672   G1ParTask g1_par_task(this, _task_queues);
5673 
5674   init_for_evac_failure(NULL);
5675 
5676   rem_set()->prepare_for_younger_refs_iterate(true);
5677 
5678   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5679   double start_par_time_sec = os::elapsedTime();
5680   double end_par_time_sec;
5681 
5682   {
5683     StrongRootsScope srs(this);
5684 
5685     if (G1CollectedHeap::use_parallel_gc_threads()) {
5686       // The individual threads will set their evac-failure closures.
5687       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5688       // These tasks use ShareHeap::_process_strong_tasks
5689       assert(UseDynamicNumberOfGCThreads ||
5690              workers()->active_workers() == workers()->total_workers(),
5691              "If not dynamic should be using all the  workers");
5692       workers()->run_task(&g1_par_task);
5693     } else {
5694       g1_par_task.set_for_termination(n_workers);
5695       g1_par_task.work(0);
5696     }
5697     end_par_time_sec = os::elapsedTime();
5698 
5699     // Closing the inner scope will execute the destructor
5700     // for the StrongRootsScope object. We record the current
5701     // elapsed time before closing the scope so that time
5702     // taken for the SRS destructor is NOT included in the
5703     // reported parallel time.
5704   }
5705 
5706   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5707   g1_policy()->phase_times()->record_par_time(par_time_ms);
5708 
5709   double code_root_fixup_time_ms =
5710         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5711   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5712 
5713   set_par_threads(0);
5714 
5715   // Process any discovered reference objects - we have
5716   // to do this _before_ we retire the GC alloc regions
5717   // as we may have to copy some 'reachable' referent
5718   // objects (and their reachable sub-graphs) that were
5719   // not copied during the pause.
5720   process_discovered_references(n_workers);
5721 
5722   // Weak root processing.
5723   {
5724     G1STWIsAliveClosure is_alive(this);
5725     G1KeepAliveClosure keep_alive(this);
5726     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5727   }
5728 
5729   release_gc_alloc_regions(n_workers);
5730   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5731 
5732   // Reset and re-enable the hot card cache.
5733   // Note the counts for the cards in the regions in the
5734   // collection set are reset when the collection set is freed.
5735   hot_card_cache->reset_hot_cache();
5736   hot_card_cache->set_use_cache(true);
5737 
5738   // Migrate the strong code roots attached to each region in
5739   // the collection set. Ideally we would like to do this
5740   // after we have finished the scanning/evacuation of the
5741   // strong code roots for a particular heap region.
5742   migrate_strong_code_roots();
5743 
5744   if (g1_policy()->during_initial_mark_pause()) {
5745     // Reset the claim values set during marking the strong code roots
5746     reset_heap_region_claim_values();
5747   }
5748 
5749   finalize_for_evac_failure();
5750 
5751   if (evacuation_failed()) {
5752     remove_self_forwarding_pointers();
5753 
5754     // Reset the G1EvacuationFailureALot counters and flags
5755     // Note: the values are reset only when an actual
5756     // evacuation failure occurs.
5757     NOT_PRODUCT(reset_evacuation_should_fail();)
5758   }
5759 
5760   // Enqueue any remaining references remaining on the STW
5761   // reference processor's discovered lists. We need to do
5762   // this after the card table is cleaned (and verified) as
5763   // the act of enqueuing entries on to the pending list
5764   // will log these updates (and dirty their associated
5765   // cards). We need these updates logged to update any
5766   // RSets.
5767   enqueue_discovered_references(n_workers);
5768 
5769   if (G1DeferredRSUpdate) {
5770     RedirtyLoggedCardTableEntryFastClosure redirty;
5771     dirty_card_queue_set().set_closure(&redirty);
5772     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5773 
5774     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5775     dcq.merge_bufferlists(&dirty_card_queue_set());
5776     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5777   }
5778   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5779 }
5780 
5781 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5782                                      size_t* pre_used,
5783                                      FreeRegionList* free_list,
5784                                      OldRegionSet* old_proxy_set,
5785                                      HumongousRegionSet* humongous_proxy_set,
5786                                      HRRSCleanupTask* hrrs_cleanup_task,
5787                                      bool par) {
5788   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5789     if (hr->isHumongous()) {
5790       assert(hr->startsHumongous(), "we should only see starts humongous");
5791       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5792     } else {
5793       _old_set.remove_with_proxy(hr, old_proxy_set);
5794       free_region(hr, pre_used, free_list, par);
5795     }
5796   } else {
5797     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5798   }
5799 }
5800 
5801 void G1CollectedHeap::free_region(HeapRegion* hr,
5802                                   size_t* pre_used,
5803                                   FreeRegionList* free_list,
5804                                   bool par) {
5805   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5806   assert(!hr->is_empty(), "the region should not be empty");
5807   assert(free_list != NULL, "pre-condition");
5808 
5809   // Clear the card counts for this region.
5810   // Note: we only need to do this if the region is not young
5811   // (since we don't refine cards in young regions).
5812   if (!hr->is_young()) {
5813     _cg1r->hot_card_cache()->reset_card_counts(hr);
5814   }
5815   *pre_used += hr->used();
5816   hr->hr_clear(par, true /* clear_space */);
5817   free_list->add_as_head(hr);
5818 }
5819 
5820 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5821                                      size_t* pre_used,
5822                                      FreeRegionList* free_list,
5823                                      HumongousRegionSet* humongous_proxy_set,
5824                                      bool par) {
5825   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5826   assert(free_list != NULL, "pre-condition");
5827   assert(humongous_proxy_set != NULL, "pre-condition");
5828 
5829   size_t hr_used = hr->used();
5830   size_t hr_capacity = hr->capacity();
5831   size_t hr_pre_used = 0;
5832   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5833   // We need to read this before we make the region non-humongous,
5834   // otherwise the information will be gone.
5835   uint last_index = hr->last_hc_index();
5836   hr->set_notHumongous();
5837   free_region(hr, &hr_pre_used, free_list, par);
5838 
5839   uint i = hr->hrs_index() + 1;
5840   while (i < last_index) {
5841     HeapRegion* curr_hr = region_at(i);
5842     assert(curr_hr->continuesHumongous(), "invariant");
5843     curr_hr->set_notHumongous();
5844     free_region(curr_hr, &hr_pre_used, free_list, par);
5845     i += 1;
5846   }
5847   assert(hr_pre_used == hr_used,
5848          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5849                  "should be the same", hr_pre_used, hr_used));
5850   *pre_used += hr_pre_used;
5851 }
5852 
5853 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5854                                        FreeRegionList* free_list,
5855                                        OldRegionSet* old_proxy_set,
5856                                        HumongousRegionSet* humongous_proxy_set,
5857                                        bool par) {
5858   if (pre_used > 0) {
5859     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5860     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5861     assert(_summary_bytes_used >= pre_used,
5862            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5863                    "should be >= pre_used: "SIZE_FORMAT,
5864                    _summary_bytes_used, pre_used));
5865     _summary_bytes_used -= pre_used;
5866   }
5867   if (free_list != NULL && !free_list->is_empty()) {
5868     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5869     _free_list.add_as_head(free_list);
5870   }
5871   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5872     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5873     _old_set.update_from_proxy(old_proxy_set);
5874   }
5875   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5876     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5877     _humongous_set.update_from_proxy(humongous_proxy_set);
5878   }
5879 }
5880 
5881 class G1ParCleanupCTTask : public AbstractGangTask {
5882   CardTableModRefBS* _ct_bs;
5883   G1CollectedHeap* _g1h;
5884   HeapRegion* volatile _su_head;
5885 public:
5886   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5887                      G1CollectedHeap* g1h) :
5888     AbstractGangTask("G1 Par Cleanup CT Task"),
5889     _ct_bs(ct_bs), _g1h(g1h) { }
5890 
5891   void work(uint worker_id) {
5892     HeapRegion* r;
5893     while (r = _g1h->pop_dirty_cards_region()) {
5894       clear_cards(r);
5895     }
5896   }
5897 
5898   void clear_cards(HeapRegion* r) {
5899     // Cards of the survivors should have already been dirtied.
5900     if (!r->is_survivor()) {
5901       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5902     }
5903   }
5904 };
5905 
5906 #ifndef PRODUCT
5907 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5908   G1CollectedHeap* _g1h;
5909   CardTableModRefBS* _ct_bs;
5910 public:
5911   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5912     : _g1h(g1h), _ct_bs(ct_bs) { }
5913   virtual bool doHeapRegion(HeapRegion* r) {
5914     if (r->is_survivor()) {
5915       _g1h->verify_dirty_region(r);
5916     } else {
5917       _g1h->verify_not_dirty_region(r);
5918     }
5919     return false;
5920   }
5921 };
5922 
5923 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5924   // All of the region should be clean.
5925   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5926   MemRegion mr(hr->bottom(), hr->end());
5927   ct_bs->verify_not_dirty_region(mr);
5928 }
5929 
5930 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5931   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5932   // dirty allocated blocks as they allocate them. The thread that
5933   // retires each region and replaces it with a new one will do a
5934   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5935   // not dirty that area (one less thing to have to do while holding
5936   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5937   // is dirty.
5938   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5939   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5940   ct_bs->verify_dirty_region(mr);
5941 }
5942 
5943 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5944   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5945   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5946     verify_dirty_region(hr);
5947   }
5948 }
5949 
5950 void G1CollectedHeap::verify_dirty_young_regions() {
5951   verify_dirty_young_list(_young_list->first_region());
5952 }
5953 #endif
5954 
5955 void G1CollectedHeap::cleanUpCardTable() {
5956   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5957   double start = os::elapsedTime();
5958 
5959   {
5960     // Iterate over the dirty cards region list.
5961     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5962 
5963     if (G1CollectedHeap::use_parallel_gc_threads()) {
5964       set_par_threads();
5965       workers()->run_task(&cleanup_task);
5966       set_par_threads(0);
5967     } else {
5968       while (_dirty_cards_region_list) {
5969         HeapRegion* r = _dirty_cards_region_list;
5970         cleanup_task.clear_cards(r);
5971         _dirty_cards_region_list = r->get_next_dirty_cards_region();
5972         if (_dirty_cards_region_list == r) {
5973           // The last region.
5974           _dirty_cards_region_list = NULL;
5975         }
5976         r->set_next_dirty_cards_region(NULL);
5977       }
5978     }
5979 #ifndef PRODUCT
5980     if (G1VerifyCTCleanup || VerifyAfterGC) {
5981       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5982       heap_region_iterate(&cleanup_verifier);
5983     }
5984 #endif
5985   }
5986 
5987   double elapsed = os::elapsedTime() - start;
5988   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5989 }
5990 
5991 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5992   size_t pre_used = 0;
5993   FreeRegionList local_free_list("Local List for CSet Freeing");
5994 
5995   double young_time_ms     = 0.0;
5996   double non_young_time_ms = 0.0;
5997 
5998   // Since the collection set is a superset of the the young list,
5999   // all we need to do to clear the young list is clear its
6000   // head and length, and unlink any young regions in the code below
6001   _young_list->clear();
6002 
6003   G1CollectorPolicy* policy = g1_policy();
6004 
6005   double start_sec = os::elapsedTime();
6006   bool non_young = true;
6007 
6008   HeapRegion* cur = cs_head;
6009   int age_bound = -1;
6010   size_t rs_lengths = 0;
6011 
6012   while (cur != NULL) {
6013     assert(!is_on_master_free_list(cur), "sanity");
6014     if (non_young) {
6015       if (cur->is_young()) {
6016         double end_sec = os::elapsedTime();
6017         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6018         non_young_time_ms += elapsed_ms;
6019 
6020         start_sec = os::elapsedTime();
6021         non_young = false;
6022       }
6023     } else {
6024       if (!cur->is_young()) {
6025         double end_sec = os::elapsedTime();
6026         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6027         young_time_ms += elapsed_ms;
6028 
6029         start_sec = os::elapsedTime();
6030         non_young = true;
6031       }
6032     }
6033 
6034     rs_lengths += cur->rem_set()->occupied();
6035 
6036     HeapRegion* next = cur->next_in_collection_set();
6037     assert(cur->in_collection_set(), "bad CS");
6038     cur->set_next_in_collection_set(NULL);
6039     cur->set_in_collection_set(false);
6040 
6041     if (cur->is_young()) {
6042       int index = cur->young_index_in_cset();
6043       assert(index != -1, "invariant");
6044       assert((uint) index < policy->young_cset_region_length(), "invariant");
6045       size_t words_survived = _surviving_young_words[index];
6046       cur->record_surv_words_in_group(words_survived);
6047 
6048       // At this point the we have 'popped' cur from the collection set
6049       // (linked via next_in_collection_set()) but it is still in the
6050       // young list (linked via next_young_region()). Clear the
6051       // _next_young_region field.
6052       cur->set_next_young_region(NULL);
6053     } else {
6054       int index = cur->young_index_in_cset();
6055       assert(index == -1, "invariant");
6056     }
6057 
6058     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6059             (!cur->is_young() && cur->young_index_in_cset() == -1),
6060             "invariant" );
6061 
6062     if (!cur->evacuation_failed()) {
6063       MemRegion used_mr = cur->used_region();
6064 
6065       // And the region is empty.
6066       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6067       free_region(cur, &pre_used, &local_free_list, false /* par */);
6068     } else {
6069       cur->uninstall_surv_rate_group();
6070       if (cur->is_young()) {
6071         cur->set_young_index_in_cset(-1);
6072       }
6073       cur->set_not_young();
6074       cur->set_evacuation_failed(false);
6075       // The region is now considered to be old.
6076       _old_set.add(cur);
6077     }
6078     cur = next;
6079   }
6080 
6081   policy->record_max_rs_lengths(rs_lengths);
6082   policy->cset_regions_freed();
6083 
6084   double end_sec = os::elapsedTime();
6085   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6086 
6087   if (non_young) {
6088     non_young_time_ms += elapsed_ms;
6089   } else {
6090     young_time_ms += elapsed_ms;
6091   }
6092 
6093   update_sets_after_freeing_regions(pre_used, &local_free_list,
6094                                     NULL /* old_proxy_set */,
6095                                     NULL /* humongous_proxy_set */,
6096                                     false /* par */);
6097   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6098   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6099 }
6100 
6101 // This routine is similar to the above but does not record
6102 // any policy statistics or update free lists; we are abandoning
6103 // the current incremental collection set in preparation of a
6104 // full collection. After the full GC we will start to build up
6105 // the incremental collection set again.
6106 // This is only called when we're doing a full collection
6107 // and is immediately followed by the tearing down of the young list.
6108 
6109 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6110   HeapRegion* cur = cs_head;
6111 
6112   while (cur != NULL) {
6113     HeapRegion* next = cur->next_in_collection_set();
6114     assert(cur->in_collection_set(), "bad CS");
6115     cur->set_next_in_collection_set(NULL);
6116     cur->set_in_collection_set(false);
6117     cur->set_young_index_in_cset(-1);
6118     cur = next;
6119   }
6120 }
6121 
6122 void G1CollectedHeap::set_free_regions_coming() {
6123   if (G1ConcRegionFreeingVerbose) {
6124     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6125                            "setting free regions coming");
6126   }
6127 
6128   assert(!free_regions_coming(), "pre-condition");
6129   _free_regions_coming = true;
6130 }
6131 
6132 void G1CollectedHeap::reset_free_regions_coming() {
6133   assert(free_regions_coming(), "pre-condition");
6134 
6135   {
6136     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6137     _free_regions_coming = false;
6138     SecondaryFreeList_lock->notify_all();
6139   }
6140 
6141   if (G1ConcRegionFreeingVerbose) {
6142     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6143                            "reset free regions coming");
6144   }
6145 }
6146 
6147 void G1CollectedHeap::wait_while_free_regions_coming() {
6148   // Most of the time we won't have to wait, so let's do a quick test
6149   // first before we take the lock.
6150   if (!free_regions_coming()) {
6151     return;
6152   }
6153 
6154   if (G1ConcRegionFreeingVerbose) {
6155     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6156                            "waiting for free regions");
6157   }
6158 
6159   {
6160     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6161     while (free_regions_coming()) {
6162       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6163     }
6164   }
6165 
6166   if (G1ConcRegionFreeingVerbose) {
6167     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6168                            "done waiting for free regions");
6169   }
6170 }
6171 
6172 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6173   assert(heap_lock_held_for_gc(),
6174               "the heap lock should already be held by or for this thread");
6175   _young_list->push_region(hr);
6176 }
6177 
6178 class NoYoungRegionsClosure: public HeapRegionClosure {
6179 private:
6180   bool _success;
6181 public:
6182   NoYoungRegionsClosure() : _success(true) { }
6183   bool doHeapRegion(HeapRegion* r) {
6184     if (r->is_young()) {
6185       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6186                              r->bottom(), r->end());
6187       _success = false;
6188     }
6189     return false;
6190   }
6191   bool success() { return _success; }
6192 };
6193 
6194 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6195   bool ret = _young_list->check_list_empty(check_sample);
6196 
6197   if (check_heap) {
6198     NoYoungRegionsClosure closure;
6199     heap_region_iterate(&closure);
6200     ret = ret && closure.success();
6201   }
6202 
6203   return ret;
6204 }
6205 
6206 class TearDownRegionSetsClosure : public HeapRegionClosure {
6207 private:
6208   OldRegionSet *_old_set;
6209 
6210 public:
6211   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6212 
6213   bool doHeapRegion(HeapRegion* r) {
6214     if (r->is_empty()) {
6215       // We ignore empty regions, we'll empty the free list afterwards
6216     } else if (r->is_young()) {
6217       // We ignore young regions, we'll empty the young list afterwards
6218     } else if (r->isHumongous()) {
6219       // We ignore humongous regions, we're not tearing down the
6220       // humongous region set
6221     } else {
6222       // The rest should be old
6223       _old_set->remove(r);
6224     }
6225     return false;
6226   }
6227 
6228   ~TearDownRegionSetsClosure() {
6229     assert(_old_set->is_empty(), "post-condition");
6230   }
6231 };
6232 
6233 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6234   assert_at_safepoint(true /* should_be_vm_thread */);
6235 
6236   if (!free_list_only) {
6237     TearDownRegionSetsClosure cl(&_old_set);
6238     heap_region_iterate(&cl);
6239 
6240     // Need to do this after the heap iteration to be able to
6241     // recognize the young regions and ignore them during the iteration.
6242     _young_list->empty_list();
6243   }
6244   _free_list.remove_all();
6245 }
6246 
6247 class RebuildRegionSetsClosure : public HeapRegionClosure {
6248 private:
6249   bool            _free_list_only;
6250   OldRegionSet*   _old_set;
6251   FreeRegionList* _free_list;
6252   size_t          _total_used;
6253 
6254 public:
6255   RebuildRegionSetsClosure(bool free_list_only,
6256                            OldRegionSet* old_set, FreeRegionList* free_list) :
6257     _free_list_only(free_list_only),
6258     _old_set(old_set), _free_list(free_list), _total_used(0) {
6259     assert(_free_list->is_empty(), "pre-condition");
6260     if (!free_list_only) {
6261       assert(_old_set->is_empty(), "pre-condition");
6262     }
6263   }
6264 
6265   bool doHeapRegion(HeapRegion* r) {
6266     if (r->continuesHumongous()) {
6267       return false;
6268     }
6269 
6270     if (r->is_empty()) {
6271       // Add free regions to the free list
6272       _free_list->add_as_tail(r);
6273     } else if (!_free_list_only) {
6274       assert(!r->is_young(), "we should not come across young regions");
6275 
6276       if (r->isHumongous()) {
6277         // We ignore humongous regions, we left the humongous set unchanged
6278       } else {
6279         // The rest should be old, add them to the old set
6280         _old_set->add(r);
6281       }
6282       _total_used += r->used();
6283     }
6284 
6285     return false;
6286   }
6287 
6288   size_t total_used() {
6289     return _total_used;
6290   }
6291 };
6292 
6293 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6294   assert_at_safepoint(true /* should_be_vm_thread */);
6295 
6296   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6297   heap_region_iterate(&cl);
6298 
6299   if (!free_list_only) {
6300     _summary_bytes_used = cl.total_used();
6301   }
6302   assert(_summary_bytes_used == recalculate_used(),
6303          err_msg("inconsistent _summary_bytes_used, "
6304                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6305                  _summary_bytes_used, recalculate_used()));
6306 }
6307 
6308 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6309   _refine_cte_cl->set_concurrent(concurrent);
6310 }
6311 
6312 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6313   HeapRegion* hr = heap_region_containing(p);
6314   if (hr == NULL) {
6315     return false;
6316   } else {
6317     return hr->is_in(p);
6318   }
6319 }
6320 
6321 // Methods for the mutator alloc region
6322 
6323 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6324                                                       bool force) {
6325   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6326   assert(!force || g1_policy()->can_expand_young_list(),
6327          "if force is true we should be able to expand the young list");
6328   bool young_list_full = g1_policy()->is_young_list_full();
6329   if (force || !young_list_full) {
6330     HeapRegion* new_alloc_region = new_region(word_size,
6331                                               false /* do_expand */);
6332     if (new_alloc_region != NULL) {
6333       set_region_short_lived_locked(new_alloc_region);
6334       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6335       return new_alloc_region;
6336     }
6337   }
6338   return NULL;
6339 }
6340 
6341 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6342                                                   size_t allocated_bytes) {
6343   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6344   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6345 
6346   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6347   _summary_bytes_used += allocated_bytes;
6348   _hr_printer.retire(alloc_region);
6349   // We update the eden sizes here, when the region is retired,
6350   // instead of when it's allocated, since this is the point that its
6351   // used space has been recored in _summary_bytes_used.
6352   g1mm()->update_eden_size();
6353 }
6354 
6355 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6356                                                     bool force) {
6357   return _g1h->new_mutator_alloc_region(word_size, force);
6358 }
6359 
6360 void G1CollectedHeap::set_par_threads() {
6361   // Don't change the number of workers.  Use the value previously set
6362   // in the workgroup.
6363   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6364   uint n_workers = workers()->active_workers();
6365   assert(UseDynamicNumberOfGCThreads ||
6366            n_workers == workers()->total_workers(),
6367       "Otherwise should be using the total number of workers");
6368   if (n_workers == 0) {
6369     assert(false, "Should have been set in prior evacuation pause.");
6370     n_workers = ParallelGCThreads;
6371     workers()->set_active_workers(n_workers);
6372   }
6373   set_par_threads(n_workers);
6374 }
6375 
6376 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6377                                        size_t allocated_bytes) {
6378   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6379 }
6380 
6381 // Methods for the GC alloc regions
6382 
6383 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6384                                                  uint count,
6385                                                  GCAllocPurpose ap) {
6386   assert(FreeList_lock->owned_by_self(), "pre-condition");
6387 
6388   if (count < g1_policy()->max_regions(ap)) {
6389     HeapRegion* new_alloc_region = new_region(word_size,
6390                                               true /* do_expand */);
6391     if (new_alloc_region != NULL) {
6392       // We really only need to do this for old regions given that we
6393       // should never scan survivors. But it doesn't hurt to do it
6394       // for survivors too.
6395       new_alloc_region->set_saved_mark();
6396       if (ap == GCAllocForSurvived) {
6397         new_alloc_region->set_survivor();
6398         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6399       } else {
6400         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6401       }
6402       bool during_im = g1_policy()->during_initial_mark_pause();
6403       new_alloc_region->note_start_of_copying(during_im);
6404       return new_alloc_region;
6405     } else {
6406       g1_policy()->note_alloc_region_limit_reached(ap);
6407     }
6408   }
6409   return NULL;
6410 }
6411 
6412 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6413                                              size_t allocated_bytes,
6414                                              GCAllocPurpose ap) {
6415   bool during_im = g1_policy()->during_initial_mark_pause();
6416   alloc_region->note_end_of_copying(during_im);
6417   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6418   if (ap == GCAllocForSurvived) {
6419     young_list()->add_survivor_region(alloc_region);
6420   } else {
6421     _old_set.add(alloc_region);
6422   }
6423   _hr_printer.retire(alloc_region);
6424 }
6425 
6426 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6427                                                        bool force) {
6428   assert(!force, "not supported for GC alloc regions");
6429   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6430 }
6431 
6432 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6433                                           size_t allocated_bytes) {
6434   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6435                                GCAllocForSurvived);
6436 }
6437 
6438 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6439                                                   bool force) {
6440   assert(!force, "not supported for GC alloc regions");
6441   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6442 }
6443 
6444 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6445                                      size_t allocated_bytes) {
6446   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6447                                GCAllocForTenured);
6448 }
6449 // Heap region set verification
6450 
6451 class VerifyRegionListsClosure : public HeapRegionClosure {
6452 private:
6453   FreeRegionList*     _free_list;
6454   OldRegionSet*       _old_set;
6455   HumongousRegionSet* _humongous_set;
6456   uint                _region_count;
6457 
6458 public:
6459   VerifyRegionListsClosure(OldRegionSet* old_set,
6460                            HumongousRegionSet* humongous_set,
6461                            FreeRegionList* free_list) :
6462     _old_set(old_set), _humongous_set(humongous_set),
6463     _free_list(free_list), _region_count(0) { }
6464 
6465   uint region_count() { return _region_count; }
6466 
6467   bool doHeapRegion(HeapRegion* hr) {
6468     _region_count += 1;
6469 
6470     if (hr->continuesHumongous()) {
6471       return false;
6472     }
6473 
6474     if (hr->is_young()) {
6475       // TODO
6476     } else if (hr->startsHumongous()) {
6477       _humongous_set->verify_next_region(hr);
6478     } else if (hr->is_empty()) {
6479       _free_list->verify_next_region(hr);
6480     } else {
6481       _old_set->verify_next_region(hr);
6482     }
6483     return false;
6484   }
6485 };
6486 
6487 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6488                                              HeapWord* bottom) {
6489   HeapWord* end = bottom + HeapRegion::GrainWords;
6490   MemRegion mr(bottom, end);
6491   assert(_g1_reserved.contains(mr), "invariant");
6492   // This might return NULL if the allocation fails
6493   return new HeapRegion(hrs_index, _bot_shared, mr);
6494 }
6495 
6496 void G1CollectedHeap::verify_region_sets() {
6497   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6498 
6499   // First, check the explicit lists.
6500   _free_list.verify();
6501   {
6502     // Given that a concurrent operation might be adding regions to
6503     // the secondary free list we have to take the lock before
6504     // verifying it.
6505     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6506     _secondary_free_list.verify();
6507   }
6508   _old_set.verify();
6509   _humongous_set.verify();
6510 
6511   // If a concurrent region freeing operation is in progress it will
6512   // be difficult to correctly attributed any free regions we come
6513   // across to the correct free list given that they might belong to
6514   // one of several (free_list, secondary_free_list, any local lists,
6515   // etc.). So, if that's the case we will skip the rest of the
6516   // verification operation. Alternatively, waiting for the concurrent
6517   // operation to complete will have a non-trivial effect on the GC's
6518   // operation (no concurrent operation will last longer than the
6519   // interval between two calls to verification) and it might hide
6520   // any issues that we would like to catch during testing.
6521   if (free_regions_coming()) {
6522     return;
6523   }
6524 
6525   // Make sure we append the secondary_free_list on the free_list so
6526   // that all free regions we will come across can be safely
6527   // attributed to the free_list.
6528   append_secondary_free_list_if_not_empty_with_lock();
6529 
6530   // Finally, make sure that the region accounting in the lists is
6531   // consistent with what we see in the heap.
6532   _old_set.verify_start();
6533   _humongous_set.verify_start();
6534   _free_list.verify_start();
6535 
6536   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6537   heap_region_iterate(&cl);
6538 
6539   _old_set.verify_end();
6540   _humongous_set.verify_end();
6541   _free_list.verify_end();
6542 }
6543 
6544 // Optimized nmethod scanning
6545 
6546 class RegisterNMethodOopClosure: public OopClosure {
6547   G1CollectedHeap* _g1h;
6548   nmethod* _nm;
6549 
6550   template <class T> void do_oop_work(T* p) {
6551     T heap_oop = oopDesc::load_heap_oop(p);
6552     if (!oopDesc::is_null(heap_oop)) {
6553       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6554       HeapRegion* hr = _g1h->heap_region_containing(obj);
6555       assert(!hr->isHumongous(), "code root in humongous region?");
6556 
6557       // HeapRegion::add_strong_code_root() avoids adding duplicate
6558       // entries but having duplicates is  OK since we "mark" nmethods
6559       // as visited when we scan the strong code root lists during the GC.
6560       hr->add_strong_code_root(_nm);
6561       assert(hr->strong_code_root_list()->contains(_nm), "push failed?");
6562     }
6563   }
6564 
6565 public:
6566   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6567     _g1h(g1h), _nm(nm) {}
6568 
6569   void do_oop(oop* p)       { do_oop_work(p); }
6570   void do_oop(narrowOop* p) { do_oop_work(p); }
6571 };
6572 
6573 class UnregisterNMethodOopClosure: public OopClosure {
6574   G1CollectedHeap* _g1h;
6575   nmethod* _nm;
6576 
6577   template <class T> void do_oop_work(T* p) {
6578     T heap_oop = oopDesc::load_heap_oop(p);
6579     if (!oopDesc::is_null(heap_oop)) {
6580       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6581       HeapRegion* hr = _g1h->heap_region_containing(obj);
6582       assert(!hr->isHumongous(), "code root in humongous region?");
6583       hr->remove_strong_code_root(_nm);
6584       assert(!hr->strong_code_root_list()->contains(_nm), "remove failed?");
6585     }
6586   }
6587 
6588 public:
6589   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6590     _g1h(g1h), _nm(nm) {}
6591 
6592   void do_oop(oop* p)       { do_oop_work(p); }
6593   void do_oop(narrowOop* p) { do_oop_work(p); }
6594 };
6595 
6596 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6597   guarantee(nm != NULL, "sanity");
6598   RegisterNMethodOopClosure reg_cl(this, nm);
6599   nm->oops_do(&reg_cl);
6600 }
6601 
6602 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6603   guarantee(nm != NULL, "sanity");
6604   UnregisterNMethodOopClosure reg_cl(this, nm);
6605   nm->oops_do(&reg_cl);
6606 }
6607 
6608 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6609 public:
6610   bool doHeapRegion(HeapRegion *hr) {
6611     assert(!hr->isHumongous(), "humongous region in collection set?");
6612     hr->migrate_strong_code_roots();
6613     return false;
6614   }
6615 };
6616 
6617 void G1CollectedHeap::migrate_strong_code_roots() {
6618   MigrateCodeRootsHeapRegionClosure cl;
6619   double migrate_start = os::elapsedTime();
6620   collection_set_iterate(&cl);
6621   double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6622   g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6623 }
6624 
6625 // Mark all the code roots that point into regions *not* in the
6626 // collection set.
6627 //
6628 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6629 // walking the the code roots lists of regions not in the collection
6630 // set. Suppose we have an nmethod (M) that points to objects in two
6631 // separate regions - one in the collection set (R1) and one not (R2).
6632 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6633 // nmethod M when walking the code roots for R1. When we come to scan
6634 // the code roots for R2, we would see that M is already marked and it
6635 // would be skipped and the objects in R2 that are referenced from M
6636 // would not be evacuated.
6637 
6638 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6639 
6640   class MarkStrongCodeRootOopClosure: public OopClosure {
6641     ConcurrentMark* _cm;
6642     HeapRegion* _hr;
6643     uint _worker_id;
6644 
6645     template <class T> void do_oop_work(T* p) {
6646       T heap_oop = oopDesc::load_heap_oop(p);
6647       if (!oopDesc::is_null(heap_oop)) {
6648         oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6649         // Only mark objects in the region (which is assumed
6650         // to be not in the collection set).
6651         if (_hr->is_in(obj)) {
6652           _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6653         }
6654       }
6655     }
6656 
6657   public:
6658     MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6659       _cm(cm), _hr(hr), _worker_id(worker_id) {
6660       assert(!_hr->in_collection_set(), "sanity");
6661     }
6662 
6663     void do_oop(narrowOop* p) { do_oop_work(p); }
6664     void do_oop(oop* p)       { do_oop_work(p); }
6665   };
6666 
6667   MarkStrongCodeRootOopClosure _oop_cl;
6668 
6669 public:
6670   MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6671     _oop_cl(cm, hr, worker_id) {}
6672 
6673   void do_code_blob(CodeBlob* cb) {
6674     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6675     if (nm != NULL) {
6676       nm->oops_do(&_oop_cl);
6677     }
6678   }
6679 };
6680 
6681 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6682   G1CollectedHeap* _g1h;
6683   uint _worker_id;
6684 
6685 public:
6686   MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6687     _g1h(g1h), _worker_id(worker_id) {}
6688 
6689   bool doHeapRegion(HeapRegion *hr) {
6690     if (hr->isHumongous()) {
6691       // Code roots should never be attached to a humongous region
6692       assert(hr->strong_code_root_list()->is_empty(), "sanity");
6693       return false;
6694     }
6695 
6696     if (hr->in_collection_set()) {
6697       // Don't mark code roots into regions in the collection set here.
6698       // They will be marked when we scan them.
6699       return false;
6700     }
6701 
6702     MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6703     hr->strong_code_roots_do(&cb_cl);
6704     return false;
6705   }
6706 };
6707 
6708 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6709   MarkStrongCodeRootsHRClosure cl(this, worker_id);
6710   heap_region_par_iterate_chunked(&cl,
6711                                   worker_id,
6712                                   workers()->active_workers(),
6713                                   HeapRegion::ParMarkRootClaimValue);
6714 }
6715 
6716 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6717   G1CollectedHeap* _g1h;
6718 
6719 public:
6720   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6721     _g1h(g1h) {}
6722 
6723   void do_code_blob(CodeBlob* cb) {
6724     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6725     if (nm == NULL) {
6726       return;
6727     }
6728 
6729     if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6730       _g1h->register_nmethod(nm);
6731     }
6732   }
6733 };
6734 
6735 void G1CollectedHeap::rebuild_strong_code_roots() {
6736   RebuildStrongCodeRootClosure blob_cl(this);
6737   CodeCache::blobs_do(&blob_cl);
6738 }