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/g1YCTypes.hpp"
  43 #include "gc_implementation/g1/heapRegion.inline.hpp"
  44 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  46 #include "gc_implementation/g1/vm_operations_g1.hpp"
  47 #include "gc_implementation/shared/gcHeapSummary.hpp"
  48 #include "gc_implementation/shared/gcTimer.hpp"
  49 #include "gc_implementation/shared/gcTrace.hpp"
  50 #include "gc_implementation/shared/gcTraceTime.hpp"
  51 #include "gc_implementation/shared/isGCActiveMark.hpp"
  52 #include "memory/gcLocker.inline.hpp"
  53 #include "memory/genOopClosures.inline.hpp"
  54 #include "memory/generationSpec.hpp"
  55 #include "memory/referenceProcessor.hpp"
  56 #include "oops/oop.inline.hpp"
  57 #include "oops/oop.pcgc.inline.hpp"
  58 #include "runtime/vmThread.hpp"
  59 
  60 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  61 
  62 // turn it on so that the contents of the young list (scan-only /
  63 // to-be-collected) are printed at "strategic" points before / during
  64 // / after the collection --- this is useful for debugging
  65 #define YOUNG_LIST_VERBOSE 0
  66 // CURRENT STATUS
  67 // This file is under construction.  Search for "FIXME".
  68 
  69 // INVARIANTS/NOTES
  70 //
  71 // All allocation activity covered by the G1CollectedHeap interface is
  72 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  73 // and allocate_new_tlab, which are the "entry" points to the
  74 // allocation code from the rest of the JVM.  (Note that this does not
  75 // apply to TLAB allocation, which is not part of this interface: it
  76 // is done by clients of this interface.)
  77 
  78 // Notes on implementation of parallelism in different tasks.
  79 //
  80 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  81 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  82 // It does use run_task() which sets _n_workers in the task.
  83 // G1ParTask executes g1_process_strong_roots() ->
  84 // SharedHeap::process_strong_roots() which calls eventually to
  85 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  86 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  87 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  88 //
  89 
  90 // Local to this file.
  91 
  92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  93   SuspendibleThreadSet* _sts;
  94   G1RemSet* _g1rs;
  95   ConcurrentG1Refine* _cg1r;
  96   bool _concurrent;
  97 public:
  98   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  99                               G1RemSet* g1rs,
 100                               ConcurrentG1Refine* cg1r) :
 101     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
 102   {}
 103   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 104     bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
 105     // This path is executed by the concurrent refine or mutator threads,
 106     // concurrently, and so we do not care if card_ptr contains references
 107     // that point into the collection set.
 108     assert(!oops_into_cset, "should be");
 109 
 110     if (_concurrent && _sts->should_yield()) {
 111       // Caller will actually yield.
 112       return false;
 113     }
 114     // Otherwise, we finished successfully; return true.
 115     return true;
 116   }
 117   void set_concurrent(bool b) { _concurrent = b; }
 118 };
 119 
 120 
 121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 122   int _calls;
 123   G1CollectedHeap* _g1h;
 124   CardTableModRefBS* _ctbs;
 125   int _histo[256];
 126 public:
 127   ClearLoggedCardTableEntryClosure() :
 128     _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
 129   {
 130     for (int i = 0; i < 256; i++) _histo[i] = 0;
 131   }
 132   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 133     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 134       _calls++;
 135       unsigned char* ujb = (unsigned char*)card_ptr;
 136       int ind = (int)(*ujb);
 137       _histo[ind]++;
 138       *card_ptr = -1;
 139     }
 140     return true;
 141   }
 142   int calls() { return _calls; }
 143   void print_histo() {
 144     gclog_or_tty->print_cr("Card table value histogram:");
 145     for (int i = 0; i < 256; i++) {
 146       if (_histo[i] != 0) {
 147         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 148       }
 149     }
 150   }
 151 };
 152 
 153 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 154   int _calls;
 155   G1CollectedHeap* _g1h;
 156   CardTableModRefBS* _ctbs;
 157 public:
 158   RedirtyLoggedCardTableEntryClosure() :
 159     _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
 160 
 161   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 162     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 163       _calls++;
 164       *card_ptr = 0;
 165     }
 166     return true;
 167   }
 168   int calls() { return _calls; }
 169 };
 170 
 171 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 172 public:
 173   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 174     *card_ptr = CardTableModRefBS::dirty_card_val();
 175     return true;
 176   }
 177 };
 178 
 179 YoungList::YoungList(G1CollectedHeap* g1h) :
 180     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 181     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 182   guarantee(check_list_empty(false), "just making sure...");
 183 }
 184 
 185 void YoungList::push_region(HeapRegion *hr) {
 186   assert(!hr->is_young(), "should not already be young");
 187   assert(hr->get_next_young_region() == NULL, "cause it should!");
 188 
 189   hr->set_next_young_region(_head);
 190   _head = hr;
 191 
 192   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 193   ++_length;
 194 }
 195 
 196 void YoungList::add_survivor_region(HeapRegion* hr) {
 197   assert(hr->is_survivor(), "should be flagged as survivor region");
 198   assert(hr->get_next_young_region() == NULL, "cause it should!");
 199 
 200   hr->set_next_young_region(_survivor_head);
 201   if (_survivor_head == NULL) {
 202     _survivor_tail = hr;
 203   }
 204   _survivor_head = hr;
 205   ++_survivor_length;
 206 }
 207 
 208 void YoungList::empty_list(HeapRegion* list) {
 209   while (list != NULL) {
 210     HeapRegion* next = list->get_next_young_region();
 211     list->set_next_young_region(NULL);
 212     list->uninstall_surv_rate_group();
 213     list->set_not_young();
 214     list = next;
 215   }
 216 }
 217 
 218 void YoungList::empty_list() {
 219   assert(check_list_well_formed(), "young list should be well formed");
 220 
 221   empty_list(_head);
 222   _head = NULL;
 223   _length = 0;
 224 
 225   empty_list(_survivor_head);
 226   _survivor_head = NULL;
 227   _survivor_tail = NULL;
 228   _survivor_length = 0;
 229 
 230   _last_sampled_rs_lengths = 0;
 231 
 232   assert(check_list_empty(false), "just making sure...");
 233 }
 234 
 235 bool YoungList::check_list_well_formed() {
 236   bool ret = true;
 237 
 238   uint length = 0;
 239   HeapRegion* curr = _head;
 240   HeapRegion* last = NULL;
 241   while (curr != NULL) {
 242     if (!curr->is_young()) {
 243       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 244                              "incorrectly tagged (y: %d, surv: %d)",
 245                              curr->bottom(), curr->end(),
 246                              curr->is_young(), curr->is_survivor());
 247       ret = false;
 248     }
 249     ++length;
 250     last = curr;
 251     curr = curr->get_next_young_region();
 252   }
 253   ret = ret && (length == _length);
 254 
 255   if (!ret) {
 256     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 257     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 258                            length, _length);
 259   }
 260 
 261   return ret;
 262 }
 263 
 264 bool YoungList::check_list_empty(bool check_sample) {
 265   bool ret = true;
 266 
 267   if (_length != 0) {
 268     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 269                   _length);
 270     ret = false;
 271   }
 272   if (check_sample && _last_sampled_rs_lengths != 0) {
 273     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 274     ret = false;
 275   }
 276   if (_head != NULL) {
 277     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 278     ret = false;
 279   }
 280   if (!ret) {
 281     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 282   }
 283 
 284   return ret;
 285 }
 286 
 287 void
 288 YoungList::rs_length_sampling_init() {
 289   _sampled_rs_lengths = 0;
 290   _curr               = _head;
 291 }
 292 
 293 bool
 294 YoungList::rs_length_sampling_more() {
 295   return _curr != NULL;
 296 }
 297 
 298 void
 299 YoungList::rs_length_sampling_next() {
 300   assert( _curr != NULL, "invariant" );
 301   size_t rs_length = _curr->rem_set()->occupied();
 302 
 303   _sampled_rs_lengths += rs_length;
 304 
 305   // The current region may not yet have been added to the
 306   // incremental collection set (it gets added when it is
 307   // retired as the current allocation region).
 308   if (_curr->in_collection_set()) {
 309     // Update the collection set policy information for this region
 310     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 311   }
 312 
 313   _curr = _curr->get_next_young_region();
 314   if (_curr == NULL) {
 315     _last_sampled_rs_lengths = _sampled_rs_lengths;
 316     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 317   }
 318 }
 319 
 320 void
 321 YoungList::reset_auxilary_lists() {
 322   guarantee( is_empty(), "young list should be empty" );
 323   assert(check_list_well_formed(), "young list should be well formed");
 324 
 325   // Add survivor regions to SurvRateGroup.
 326   _g1h->g1_policy()->note_start_adding_survivor_regions();
 327   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 328 
 329   int young_index_in_cset = 0;
 330   for (HeapRegion* curr = _survivor_head;
 331        curr != NULL;
 332        curr = curr->get_next_young_region()) {
 333     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 334 
 335     // The region is a non-empty survivor so let's add it to
 336     // the incremental collection set for the next evacuation
 337     // pause.
 338     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 339     young_index_in_cset += 1;
 340   }
 341   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 342   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 343 
 344   _head   = _survivor_head;
 345   _length = _survivor_length;
 346   if (_survivor_head != NULL) {
 347     assert(_survivor_tail != NULL, "cause it shouldn't be");
 348     assert(_survivor_length > 0, "invariant");
 349     _survivor_tail->set_next_young_region(NULL);
 350   }
 351 
 352   // Don't clear the survivor list handles until the start of
 353   // the next evacuation pause - we need it in order to re-tag
 354   // the survivor regions from this evacuation pause as 'young'
 355   // at the start of the next.
 356 
 357   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 358 
 359   assert(check_list_well_formed(), "young list should be well formed");
 360 }
 361 
 362 void YoungList::print() {
 363   HeapRegion* lists[] = {_head,   _survivor_head};
 364   const char* names[] = {"YOUNG", "SURVIVOR"};
 365 
 366   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 367     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 368     HeapRegion *curr = lists[list];
 369     if (curr == NULL)
 370       gclog_or_tty->print_cr("  empty");
 371     while (curr != NULL) {
 372       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 373                              HR_FORMAT_PARAMS(curr),
 374                              curr->prev_top_at_mark_start(),
 375                              curr->next_top_at_mark_start(),
 376                              curr->age_in_surv_rate_group_cond());
 377       curr = curr->get_next_young_region();
 378     }
 379   }
 380 
 381   gclog_or_tty->print_cr("");
 382 }
 383 
 384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 385 {
 386   // Claim the right to put the region on the dirty cards region list
 387   // by installing a self pointer.
 388   HeapRegion* next = hr->get_next_dirty_cards_region();
 389   if (next == NULL) {
 390     HeapRegion* res = (HeapRegion*)
 391       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 392                           NULL);
 393     if (res == NULL) {
 394       HeapRegion* head;
 395       do {
 396         // Put the region to the dirty cards region list.
 397         head = _dirty_cards_region_list;
 398         next = (HeapRegion*)
 399           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 400         if (next == head) {
 401           assert(hr->get_next_dirty_cards_region() == hr,
 402                  "hr->get_next_dirty_cards_region() != hr");
 403           if (next == NULL) {
 404             // The last region in the list points to itself.
 405             hr->set_next_dirty_cards_region(hr);
 406           } else {
 407             hr->set_next_dirty_cards_region(next);
 408           }
 409         }
 410       } while (next != head);
 411     }
 412   }
 413 }
 414 
 415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 416 {
 417   HeapRegion* head;
 418   HeapRegion* hr;
 419   do {
 420     head = _dirty_cards_region_list;
 421     if (head == NULL) {
 422       return NULL;
 423     }
 424     HeapRegion* new_head = head->get_next_dirty_cards_region();
 425     if (head == new_head) {
 426       // The last region.
 427       new_head = NULL;
 428     }
 429     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 430                                           head);
 431   } while (hr != head);
 432   assert(hr != NULL, "invariant");
 433   hr->set_next_dirty_cards_region(NULL);
 434   return hr;
 435 }
 436 
 437 void G1CollectedHeap::stop_conc_gc_threads() {
 438   _cg1r->stop();
 439   _cmThread->stop();
 440 }
 441 
 442 #ifdef ASSERT
 443 // A region is added to the collection set as it is retired
 444 // so an address p can point to a region which will be in the
 445 // collection set but has not yet been retired.  This method
 446 // therefore is only accurate during a GC pause after all
 447 // regions have been retired.  It is used for debugging
 448 // to check if an nmethod has references to objects that can
 449 // be move during a partial collection.  Though it can be
 450 // inaccurate, it is sufficient for G1 because the conservative
 451 // implementation of is_scavengable() for G1 will indicate that
 452 // all nmethods must be scanned during a partial collection.
 453 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 454   HeapRegion* hr = heap_region_containing(p);
 455   return hr != NULL && hr->in_collection_set();
 456 }
 457 #endif
 458 
 459 // Returns true if the reference points to an object that
 460 // can move in an incremental collection.
 461 bool G1CollectedHeap::is_scavengable(const void* p) {
 462   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 463   G1CollectorPolicy* g1p = g1h->g1_policy();
 464   HeapRegion* hr = heap_region_containing(p);
 465   if (hr == NULL) {
 466      // null
 467      assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
 468      return false;
 469   } else {
 470     return !hr->isHumongous();
 471   }
 472 }
 473 
 474 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 475   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 476   CardTableModRefBS* ct_bs = g1_barrier_set();
 477 
 478   // Count the dirty cards at the start.
 479   CountNonCleanMemRegionClosure count1(this);
 480   ct_bs->mod_card_iterate(&count1);
 481   int orig_count = count1.n();
 482 
 483   // First clear the logged cards.
 484   ClearLoggedCardTableEntryClosure clear;
 485   dcqs.set_closure(&clear);
 486   dcqs.apply_closure_to_all_completed_buffers();
 487   dcqs.iterate_closure_all_threads(false);
 488   clear.print_histo();
 489 
 490   // Now ensure that there's no dirty cards.
 491   CountNonCleanMemRegionClosure count2(this);
 492   ct_bs->mod_card_iterate(&count2);
 493   if (count2.n() != 0) {
 494     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 495                            count2.n(), orig_count);
 496   }
 497   guarantee(count2.n() == 0, "Card table should be clean.");
 498 
 499   RedirtyLoggedCardTableEntryClosure redirty;
 500   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 501   dcqs.apply_closure_to_all_completed_buffers();
 502   dcqs.iterate_closure_all_threads(false);
 503   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 504                          clear.calls(), orig_count);
 505   guarantee(redirty.calls() == clear.calls(),
 506             "Or else mechanism is broken.");
 507 
 508   CountNonCleanMemRegionClosure count3(this);
 509   ct_bs->mod_card_iterate(&count3);
 510   if (count3.n() != orig_count) {
 511     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 512                            orig_count, count3.n());
 513     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 514   }
 515 
 516   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 517 }
 518 
 519 // Private class members.
 520 
 521 G1CollectedHeap* G1CollectedHeap::_g1h;
 522 
 523 // Private methods.
 524 
 525 HeapRegion*
 526 G1CollectedHeap::new_region_try_secondary_free_list() {
 527   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 528   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 529     if (!_secondary_free_list.is_empty()) {
 530       if (G1ConcRegionFreeingVerbose) {
 531         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 532                                "secondary_free_list has %u entries",
 533                                _secondary_free_list.length());
 534       }
 535       // It looks as if there are free regions available on the
 536       // secondary_free_list. Let's move them to the free_list and try
 537       // again to allocate from it.
 538       append_secondary_free_list();
 539 
 540       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 541              "empty we should have moved at least one entry to the free_list");
 542       HeapRegion* res = _free_list.remove_head();
 543       if (G1ConcRegionFreeingVerbose) {
 544         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 545                                "allocated "HR_FORMAT" from secondary_free_list",
 546                                HR_FORMAT_PARAMS(res));
 547       }
 548       return res;
 549     }
 550 
 551     // Wait here until we get notified either when (a) there are no
 552     // more free regions coming or (b) some regions have been moved on
 553     // the secondary_free_list.
 554     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 555   }
 556 
 557   if (G1ConcRegionFreeingVerbose) {
 558     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 559                            "could not allocate from secondary_free_list");
 560   }
 561   return NULL;
 562 }
 563 
 564 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 565   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 566          "the only time we use this to allocate a humongous region is "
 567          "when we are allocating a single humongous region");
 568 
 569   HeapRegion* res;
 570   if (G1StressConcRegionFreeing) {
 571     if (!_secondary_free_list.is_empty()) {
 572       if (G1ConcRegionFreeingVerbose) {
 573         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 574                                "forced to look at the secondary_free_list");
 575       }
 576       res = new_region_try_secondary_free_list();
 577       if (res != NULL) {
 578         return res;
 579       }
 580     }
 581   }
 582   res = _free_list.remove_head_or_null();
 583   if (res == NULL) {
 584     if (G1ConcRegionFreeingVerbose) {
 585       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 586                              "res == NULL, trying the secondary_free_list");
 587     }
 588     res = new_region_try_secondary_free_list();
 589   }
 590   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 591     // Currently, only attempts to allocate GC alloc regions set
 592     // do_expand to true. So, we should only reach here during a
 593     // safepoint. If this assumption changes we might have to
 594     // reconsider the use of _expand_heap_after_alloc_failure.
 595     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 596 
 597     ergo_verbose1(ErgoHeapSizing,
 598                   "attempt heap expansion",
 599                   ergo_format_reason("region allocation request failed")
 600                   ergo_format_byte("allocation request"),
 601                   word_size * HeapWordSize);
 602     if (expand(word_size * HeapWordSize)) {
 603       // Given that expand() succeeded in expanding the heap, and we
 604       // always expand the heap by an amount aligned to the heap
 605       // region size, the free list should in theory not be empty. So
 606       // it would probably be OK to use remove_head(). But the extra
 607       // check for NULL is unlikely to be a performance issue here (we
 608       // just expanded the heap!) so let's just be conservative and
 609       // use remove_head_or_null().
 610       res = _free_list.remove_head_or_null();
 611     } else {
 612       _expand_heap_after_alloc_failure = false;
 613     }
 614   }
 615   return res;
 616 }
 617 
 618 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 619                                                         size_t word_size) {
 620   assert(isHumongous(word_size), "word_size should be humongous");
 621   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 622 
 623   uint first = G1_NULL_HRS_INDEX;
 624   if (num_regions == 1) {
 625     // Only one region to allocate, no need to go through the slower
 626     // path. The caller will attempt the expansion if this fails, so
 627     // let's not try to expand here too.
 628     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 629     if (hr != NULL) {
 630       first = hr->hrs_index();
 631     } else {
 632       first = G1_NULL_HRS_INDEX;
 633     }
 634   } else {
 635     // We can't allocate humongous regions while cleanupComplete() is
 636     // running, since some of the regions we find to be empty might not
 637     // yet be added to the free list and it is not straightforward to
 638     // know which list they are on so that we can remove them. Note
 639     // that we only need to do this if we need to allocate more than
 640     // one region to satisfy the current humongous allocation
 641     // request. If we are only allocating one region we use the common
 642     // region allocation code (see above).
 643     wait_while_free_regions_coming();
 644     append_secondary_free_list_if_not_empty_with_lock();
 645 
 646     if (free_regions() >= num_regions) {
 647       first = _hrs.find_contiguous(num_regions);
 648       if (first != G1_NULL_HRS_INDEX) {
 649         for (uint i = first; i < first + num_regions; ++i) {
 650           HeapRegion* hr = region_at(i);
 651           assert(hr->is_empty(), "sanity");
 652           assert(is_on_master_free_list(hr), "sanity");
 653           hr->set_pending_removal(true);
 654         }
 655         _free_list.remove_all_pending(num_regions);
 656       }
 657     }
 658   }
 659   return first;
 660 }
 661 
 662 HeapWord*
 663 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 664                                                            uint num_regions,
 665                                                            size_t word_size) {
 666   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 667   assert(isHumongous(word_size), "word_size should be humongous");
 668   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 669 
 670   // Index of last region in the series + 1.
 671   uint last = first + num_regions;
 672 
 673   // We need to initialize the region(s) we just discovered. This is
 674   // a bit tricky given that it can happen concurrently with
 675   // refinement threads refining cards on these regions and
 676   // potentially wanting to refine the BOT as they are scanning
 677   // those cards (this can happen shortly after a cleanup; see CR
 678   // 6991377). So we have to set up the region(s) carefully and in
 679   // a specific order.
 680 
 681   // The word size sum of all the regions we will allocate.
 682   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 683   assert(word_size <= word_size_sum, "sanity");
 684 
 685   // This will be the "starts humongous" region.
 686   HeapRegion* first_hr = region_at(first);
 687   // The header of the new object will be placed at the bottom of
 688   // the first region.
 689   HeapWord* new_obj = first_hr->bottom();
 690   // This will be the new end of the first region in the series that
 691   // should also match the end of the last region in the series.
 692   HeapWord* new_end = new_obj + word_size_sum;
 693   // This will be the new top of the first region that will reflect
 694   // this allocation.
 695   HeapWord* new_top = new_obj + word_size;
 696 
 697   // First, we need to zero the header of the space that we will be
 698   // allocating. When we update top further down, some refinement
 699   // threads might try to scan the region. By zeroing the header we
 700   // ensure that any thread that will try to scan the region will
 701   // come across the zero klass word and bail out.
 702   //
 703   // NOTE: It would not have been correct to have used
 704   // CollectedHeap::fill_with_object() and make the space look like
 705   // an int array. The thread that is doing the allocation will
 706   // later update the object header to a potentially different array
 707   // type and, for a very short period of time, the klass and length
 708   // fields will be inconsistent. This could cause a refinement
 709   // thread to calculate the object size incorrectly.
 710   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 711 
 712   // We will set up the first region as "starts humongous". This
 713   // will also update the BOT covering all the regions to reflect
 714   // that there is a single object that starts at the bottom of the
 715   // first region.
 716   first_hr->set_startsHumongous(new_top, new_end);
 717 
 718   // Then, if there are any, we will set up the "continues
 719   // humongous" regions.
 720   HeapRegion* hr = NULL;
 721   for (uint i = first + 1; i < last; ++i) {
 722     hr = region_at(i);
 723     hr->set_continuesHumongous(first_hr);
 724   }
 725   // If we have "continues humongous" regions (hr != NULL), then the
 726   // end of the last one should match new_end.
 727   assert(hr == NULL || hr->end() == new_end, "sanity");
 728 
 729   // Up to this point no concurrent thread would have been able to
 730   // do any scanning on any region in this series. All the top
 731   // fields still point to bottom, so the intersection between
 732   // [bottom,top] and [card_start,card_end] will be empty. Before we
 733   // update the top fields, we'll do a storestore to make sure that
 734   // no thread sees the update to top before the zeroing of the
 735   // object header and the BOT initialization.
 736   OrderAccess::storestore();
 737 
 738   // Now that the BOT and the object header have been initialized,
 739   // we can update top of the "starts humongous" region.
 740   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 741          "new_top should be in this region");
 742   first_hr->set_top(new_top);
 743   if (_hr_printer.is_active()) {
 744     HeapWord* bottom = first_hr->bottom();
 745     HeapWord* end = first_hr->orig_end();
 746     if ((first + 1) == last) {
 747       // the series has a single humongous region
 748       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 749     } else {
 750       // the series has more than one humongous regions
 751       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 752     }
 753   }
 754 
 755   // Now, we will update the top fields of the "continues humongous"
 756   // regions. The reason we need to do this is that, otherwise,
 757   // these regions would look empty and this will confuse parts of
 758   // G1. For example, the code that looks for a consecutive number
 759   // of empty regions will consider them empty and try to
 760   // re-allocate them. We can extend is_empty() to also include
 761   // !continuesHumongous(), but it is easier to just update the top
 762   // fields here. The way we set top for all regions (i.e., top ==
 763   // end for all regions but the last one, top == new_top for the
 764   // last one) is actually used when we will free up the humongous
 765   // region in free_humongous_region().
 766   hr = NULL;
 767   for (uint i = first + 1; i < last; ++i) {
 768     hr = region_at(i);
 769     if ((i + 1) == last) {
 770       // last continues humongous region
 771       assert(hr->bottom() < new_top && new_top <= hr->end(),
 772              "new_top should fall on this region");
 773       hr->set_top(new_top);
 774       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 775     } else {
 776       // not last one
 777       assert(new_top > hr->end(), "new_top should be above this region");
 778       hr->set_top(hr->end());
 779       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 780     }
 781   }
 782   // If we have continues humongous regions (hr != NULL), then the
 783   // end of the last one should match new_end and its top should
 784   // match new_top.
 785   assert(hr == NULL ||
 786          (hr->end() == new_end && hr->top() == new_top), "sanity");
 787 
 788   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 789   _summary_bytes_used += first_hr->used();
 790   _humongous_set.add(first_hr);
 791 
 792   return new_obj;
 793 }
 794 
 795 // If could fit into free regions w/o expansion, try.
 796 // Otherwise, if can expand, do so.
 797 // Otherwise, if using ex regions might help, try with ex given back.
 798 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 799   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 800 
 801   verify_region_sets_optional();
 802 
 803   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 804   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 805   uint x_num = expansion_regions();
 806   uint fs = _hrs.free_suffix();
 807   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 808   if (first == G1_NULL_HRS_INDEX) {
 809     // The only thing we can do now is attempt expansion.
 810     if (fs + x_num >= num_regions) {
 811       // If the number of regions we're trying to allocate for this
 812       // object is at most the number of regions in the free suffix,
 813       // then the call to humongous_obj_allocate_find_first() above
 814       // should have succeeded and we wouldn't be here.
 815       //
 816       // We should only be trying to expand when the free suffix is
 817       // not sufficient for the object _and_ we have some expansion
 818       // room available.
 819       assert(num_regions > fs, "earlier allocation should have succeeded");
 820 
 821       ergo_verbose1(ErgoHeapSizing,
 822                     "attempt heap expansion",
 823                     ergo_format_reason("humongous allocation request failed")
 824                     ergo_format_byte("allocation request"),
 825                     word_size * HeapWordSize);
 826       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 827         // Even though the heap was expanded, it might not have
 828         // reached the desired size. So, we cannot assume that the
 829         // allocation will succeed.
 830         first = humongous_obj_allocate_find_first(num_regions, word_size);
 831       }
 832     }
 833   }
 834 
 835   HeapWord* result = NULL;
 836   if (first != G1_NULL_HRS_INDEX) {
 837     result =
 838       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 839     assert(result != NULL, "it should always return a valid result");
 840 
 841     // A successful humongous object allocation changes the used space
 842     // information of the old generation so we need to recalculate the
 843     // sizes and update the jstat counters here.
 844     g1mm()->update_sizes();
 845   }
 846 
 847   verify_region_sets_optional();
 848 
 849   return result;
 850 }
 851 
 852 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 853   assert_heap_not_locked_and_not_at_safepoint();
 854   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 855 
 856   unsigned int dummy_gc_count_before;
 857   int dummy_gclocker_retry_count = 0;
 858   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 859 }
 860 
 861 HeapWord*
 862 G1CollectedHeap::mem_allocate(size_t word_size,
 863                               bool*  gc_overhead_limit_was_exceeded) {
 864   assert_heap_not_locked_and_not_at_safepoint();
 865 
 866   // Loop until the allocation is satisfied, or unsatisfied after GC.
 867   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 868     unsigned int gc_count_before;
 869 
 870     HeapWord* result = NULL;
 871     if (!isHumongous(word_size)) {
 872       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 873     } else {
 874       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 875     }
 876     if (result != NULL) {
 877       return result;
 878     }
 879 
 880     // Create the garbage collection operation...
 881     VM_G1CollectForAllocation op(gc_count_before, word_size);
 882     // ...and get the VM thread to execute it.
 883     VMThread::execute(&op);
 884 
 885     if (op.prologue_succeeded() && op.pause_succeeded()) {
 886       // If the operation was successful we'll return the result even
 887       // if it is NULL. If the allocation attempt failed immediately
 888       // after a Full GC, it's unlikely we'll be able to allocate now.
 889       HeapWord* result = op.result();
 890       if (result != NULL && !isHumongous(word_size)) {
 891         // Allocations that take place on VM operations do not do any
 892         // card dirtying and we have to do it here. We only have to do
 893         // this for non-humongous allocations, though.
 894         dirty_young_block(result, word_size);
 895       }
 896       return result;
 897     } else {
 898       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 899         return NULL;
 900       }
 901       assert(op.result() == NULL,
 902              "the result should be NULL if the VM op did not succeed");
 903     }
 904 
 905     // Give a warning if we seem to be looping forever.
 906     if ((QueuedAllocationWarningCount > 0) &&
 907         (try_count % QueuedAllocationWarningCount == 0)) {
 908       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 909     }
 910   }
 911 
 912   ShouldNotReachHere();
 913   return NULL;
 914 }
 915 
 916 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 917                                            unsigned int *gc_count_before_ret,
 918                                            int* gclocker_retry_count_ret) {
 919   // Make sure you read the note in attempt_allocation_humongous().
 920 
 921   assert_heap_not_locked_and_not_at_safepoint();
 922   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 923          "be called for humongous allocation requests");
 924 
 925   // We should only get here after the first-level allocation attempt
 926   // (attempt_allocation()) failed to allocate.
 927 
 928   // We will loop until a) we manage to successfully perform the
 929   // allocation or b) we successfully schedule a collection which
 930   // fails to perform the allocation. b) is the only case when we'll
 931   // return NULL.
 932   HeapWord* result = NULL;
 933   for (int try_count = 1; /* we'll return */; try_count += 1) {
 934     bool should_try_gc;
 935     unsigned int gc_count_before;
 936 
 937     {
 938       MutexLockerEx x(Heap_lock);
 939 
 940       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 941                                                       false /* bot_updates */);
 942       if (result != NULL) {
 943         return result;
 944       }
 945 
 946       // If we reach here, attempt_allocation_locked() above failed to
 947       // allocate a new region. So the mutator alloc region should be NULL.
 948       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 949 
 950       if (GC_locker::is_active_and_needs_gc()) {
 951         if (g1_policy()->can_expand_young_list()) {
 952           // No need for an ergo verbose message here,
 953           // can_expand_young_list() does this when it returns true.
 954           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 955                                                       false /* bot_updates */);
 956           if (result != NULL) {
 957             return result;
 958           }
 959         }
 960         should_try_gc = false;
 961       } else {
 962         // The GCLocker may not be active but the GCLocker initiated
 963         // GC may not yet have been performed (GCLocker::needs_gc()
 964         // returns true). In this case we do not try this GC and
 965         // wait until the GCLocker initiated GC is performed, and
 966         // then retry the allocation.
 967         if (GC_locker::needs_gc()) {
 968           should_try_gc = false;
 969         } else {
 970           // Read the GC count while still holding the Heap_lock.
 971           gc_count_before = total_collections();
 972           should_try_gc = true;
 973         }
 974       }
 975     }
 976 
 977     if (should_try_gc) {
 978       bool succeeded;
 979       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 980           GCCause::_g1_inc_collection_pause);
 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 unsuccessful 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           GCCause::_g1_humongous_allocation);
1107       if (result != NULL) {
1108         assert(succeeded, "only way to get back a non-NULL result");
1109         return result;
1110       }
1111 
1112       if (succeeded) {
1113         // If we get here we successfully scheduled a collection which
1114         // failed to allocate. No point in trying to allocate
1115         // further. We'll just return NULL.
1116         MutexLockerEx x(Heap_lock);
1117         *gc_count_before_ret = total_collections();
1118         return NULL;
1119       }
1120     } else {
1121       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1122         MutexLockerEx x(Heap_lock);
1123         *gc_count_before_ret = total_collections();
1124         return NULL;
1125       }
1126       // The GCLocker is either active or the GCLocker initiated
1127       // GC has not yet been performed. Stall until it is and
1128       // then retry the allocation.
1129       GC_locker::stall_until_clear();
1130       (*gclocker_retry_count_ret) += 1;
1131     }
1132 
1133     // We can reach here if we were unsuccessful in scheduling a
1134     // collection (because another thread beat us to it) or if we were
1135     // stalled due to the GC locker. In either can we should retry the
1136     // allocation attempt in case another thread successfully
1137     // performed a collection and reclaimed enough space.  Give a
1138     // warning if we seem to be looping forever.
1139 
1140     if ((QueuedAllocationWarningCount > 0) &&
1141         (try_count % QueuedAllocationWarningCount == 0)) {
1142       warning("G1CollectedHeap::attempt_allocation_humongous() "
1143               "retries %d times", try_count);
1144     }
1145   }
1146 
1147   ShouldNotReachHere();
1148   return NULL;
1149 }
1150 
1151 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1152                                        bool expect_null_mutator_alloc_region) {
1153   assert_at_safepoint(true /* should_be_vm_thread */);
1154   assert(_mutator_alloc_region.get() == NULL ||
1155                                              !expect_null_mutator_alloc_region,
1156          "the current alloc region was unexpectedly found to be non-NULL");
1157 
1158   if (!isHumongous(word_size)) {
1159     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1160                                                       false /* bot_updates */);
1161   } else {
1162     HeapWord* result = humongous_obj_allocate(word_size);
1163     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1164       g1_policy()->set_initiate_conc_mark_if_possible();
1165     }
1166     return result;
1167   }
1168 
1169   ShouldNotReachHere();
1170 }
1171 
1172 class PostMCRemSetClearClosure: public HeapRegionClosure {
1173   G1CollectedHeap* _g1h;
1174   ModRefBarrierSet* _mr_bs;
1175 public:
1176   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1177     _g1h(g1h), _mr_bs(mr_bs) {}
1178 
1179   bool doHeapRegion(HeapRegion* r) {
1180     HeapRegionRemSet* hrrs = r->rem_set();
1181 
1182     if (r->continuesHumongous()) {
1183       // We'll assert that the strong code root list and RSet is empty
1184       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1185       assert(hrrs->occupied() == 0, "RSet should be empty");
1186       return false;
1187     }
1188 
1189     _g1h->reset_gc_time_stamps(r);
1190     hrrs->clear();
1191     // You might think here that we could clear just the cards
1192     // corresponding to the used region.  But no: if we leave a dirty card
1193     // in a region we might allocate into, then it would prevent that card
1194     // from being enqueued, and cause it to be missed.
1195     // Re: the performance cost: we shouldn't be doing full GC anyway!
1196     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1197 
1198     return false;
1199   }
1200 };
1201 
1202 void G1CollectedHeap::clear_rsets_post_compaction() {
1203   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1204   heap_region_iterate(&rs_clear);
1205 }
1206 
1207 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1208   G1CollectedHeap*   _g1h;
1209   UpdateRSOopClosure _cl;
1210   int                _worker_i;
1211 public:
1212   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1213     _cl(g1->g1_rem_set(), worker_i),
1214     _worker_i(worker_i),
1215     _g1h(g1)
1216   { }
1217 
1218   bool doHeapRegion(HeapRegion* r) {
1219     if (!r->continuesHumongous()) {
1220       _cl.set_from(r);
1221       r->oop_iterate(&_cl);
1222     }
1223     return false;
1224   }
1225 };
1226 
1227 class ParRebuildRSTask: public AbstractGangTask {
1228   G1CollectedHeap* _g1;
1229 public:
1230   ParRebuildRSTask(G1CollectedHeap* g1)
1231     : AbstractGangTask("ParRebuildRSTask"),
1232       _g1(g1)
1233   { }
1234 
1235   void work(uint worker_id) {
1236     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1237     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1238                                           _g1->workers()->active_workers(),
1239                                          HeapRegion::RebuildRSClaimValue);
1240   }
1241 };
1242 
1243 class PostCompactionPrinterClosure: public HeapRegionClosure {
1244 private:
1245   G1HRPrinter* _hr_printer;
1246 public:
1247   bool doHeapRegion(HeapRegion* hr) {
1248     assert(!hr->is_young(), "not expecting to find young regions");
1249     // We only generate output for non-empty regions.
1250     if (!hr->is_empty()) {
1251       if (!hr->isHumongous()) {
1252         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1253       } else if (hr->startsHumongous()) {
1254         if (hr->region_num() == 1) {
1255           // single humongous region
1256           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1257         } else {
1258           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1259         }
1260       } else {
1261         assert(hr->continuesHumongous(), "only way to get here");
1262         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1263       }
1264     }
1265     return false;
1266   }
1267 
1268   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1269     : _hr_printer(hr_printer) { }
1270 };
1271 
1272 void G1CollectedHeap::print_hrs_post_compaction() {
1273   PostCompactionPrinterClosure cl(hr_printer());
1274   heap_region_iterate(&cl);
1275 }
1276 
1277 bool G1CollectedHeap::do_collection(bool explicit_gc,
1278                                     bool clear_all_soft_refs,
1279                                     size_t word_size) {
1280   assert_at_safepoint(true /* should_be_vm_thread */);
1281 
1282   if (GC_locker::check_active_before_gc()) {
1283     return false;
1284   }
1285 
1286   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1287   gc_timer->register_gc_start(os::elapsed_counter());
1288 
1289   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1290   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1291 
1292   SvcGCMarker sgcm(SvcGCMarker::FULL);
1293   ResourceMark rm;
1294 
1295   print_heap_before_gc();
1296   trace_heap_before_gc(gc_tracer);
1297 
1298   size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1299 
1300   HRSPhaseSetter x(HRSPhaseFullGC);
1301   verify_region_sets_optional();
1302 
1303   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1304                            collector_policy()->should_clear_all_soft_refs();
1305 
1306   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1307 
1308   {
1309     IsGCActiveMark x;
1310 
1311     // Timing
1312     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1313     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1314     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1315 
1316     {
1317       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1318       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1319       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1320 
1321       double start = os::elapsedTime();
1322       g1_policy()->record_full_collection_start();
1323 
1324       // Note: When we have a more flexible GC logging framework that
1325       // allows us to add optional attributes to a GC log record we
1326       // could consider timing and reporting how long we wait in the
1327       // following two methods.
1328       wait_while_free_regions_coming();
1329       // If we start the compaction before the CM threads finish
1330       // scanning the root regions we might trip them over as we'll
1331       // be moving objects / updating references. So let's wait until
1332       // they are done. By telling them to abort, they should complete
1333       // early.
1334       _cm->root_regions()->abort();
1335       _cm->root_regions()->wait_until_scan_finished();
1336       append_secondary_free_list_if_not_empty_with_lock();
1337 
1338       gc_prologue(true);
1339       increment_total_collections(true /* full gc */);
1340       increment_old_marking_cycles_started();
1341 
1342       assert(used() == recalculate_used(), "Should be equal");
1343 
1344       verify_before_gc();
1345 
1346       pre_full_gc_dump(gc_timer);
1347 
1348       COMPILER2_PRESENT(DerivedPointerTable::clear());
1349 
1350       // Disable discovery and empty the discovered lists
1351       // for the CM ref processor.
1352       ref_processor_cm()->disable_discovery();
1353       ref_processor_cm()->abandon_partial_discovery();
1354       ref_processor_cm()->verify_no_references_recorded();
1355 
1356       // Abandon current iterations of concurrent marking and concurrent
1357       // refinement, if any are in progress. We have to do this before
1358       // wait_until_scan_finished() below.
1359       concurrent_mark()->abort();
1360 
1361       // Make sure we'll choose a new allocation region afterwards.
1362       release_mutator_alloc_region();
1363       abandon_gc_alloc_regions();
1364       g1_rem_set()->cleanupHRRS();
1365 
1366       // We should call this after we retire any currently active alloc
1367       // regions so that all the ALLOC / RETIRE events are generated
1368       // before the start GC event.
1369       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1370 
1371       // We may have added regions to the current incremental collection
1372       // set between the last GC or pause and now. We need to clear the
1373       // incremental collection set and then start rebuilding it afresh
1374       // after this full GC.
1375       abandon_collection_set(g1_policy()->inc_cset_head());
1376       g1_policy()->clear_incremental_cset();
1377       g1_policy()->stop_incremental_cset_building();
1378 
1379       tear_down_region_sets(false /* free_list_only */);
1380       g1_policy()->set_gcs_are_young(true);
1381 
1382       // See the comments in g1CollectedHeap.hpp and
1383       // G1CollectedHeap::ref_processing_init() about
1384       // how reference processing currently works in G1.
1385 
1386       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1387       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1388 
1389       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1390       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1391 
1392       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1393       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1394 
1395       // Do collection work
1396       {
1397         HandleMark hm;  // Discard invalid handles created during gc
1398         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1399       }
1400 
1401       assert(free_regions() == 0, "we should not have added any free regions");
1402       rebuild_region_sets(false /* free_list_only */);
1403 
1404       // Enqueue any discovered reference objects that have
1405       // not been removed from the discovered lists.
1406       ref_processor_stw()->enqueue_discovered_references();
1407 
1408       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1409 
1410       MemoryService::track_memory_usage();
1411 
1412       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1413       ref_processor_stw()->verify_no_references_recorded();
1414 
1415       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1416       ClassLoaderDataGraph::purge();
1417       MetaspaceAux::verify_metrics();
1418 
1419       // Note: since we've just done a full GC, concurrent
1420       // marking is no longer active. Therefore we need not
1421       // re-enable reference discovery for the CM ref processor.
1422       // That will be done at the start of the next marking cycle.
1423       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1424       ref_processor_cm()->verify_no_references_recorded();
1425 
1426       reset_gc_time_stamp();
1427       // Since everything potentially moved, we will clear all remembered
1428       // sets, and clear all cards.  Later we will rebuild remembered
1429       // sets. We will also reset the GC time stamps of the regions.
1430       clear_rsets_post_compaction();
1431       check_gc_time_stamps();
1432 
1433       // Resize the heap if necessary.
1434       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1435 
1436       if (_hr_printer.is_active()) {
1437         // We should do this after we potentially resize the heap so
1438         // that all the COMMIT / UNCOMMIT events are generated before
1439         // the end GC event.
1440 
1441         print_hrs_post_compaction();
1442         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1443       }
1444 
1445       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1446       if (hot_card_cache->use_cache()) {
1447         hot_card_cache->reset_card_counts();
1448         hot_card_cache->reset_hot_cache();
1449       }
1450 
1451       // Rebuild remembered sets of all regions.
1452       if (G1CollectedHeap::use_parallel_gc_threads()) {
1453         uint n_workers =
1454           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1455                                                   workers()->active_workers(),
1456                                                   Threads::number_of_non_daemon_threads());
1457         assert(UseDynamicNumberOfGCThreads ||
1458                n_workers == workers()->total_workers(),
1459                "If not dynamic should be using all the  workers");
1460         workers()->set_active_workers(n_workers);
1461         // Set parallel threads in the heap (_n_par_threads) only
1462         // before a parallel phase and always reset it to 0 after
1463         // the phase so that the number of parallel threads does
1464         // no get carried forward to a serial phase where there
1465         // may be code that is "possibly_parallel".
1466         set_par_threads(n_workers);
1467 
1468         ParRebuildRSTask rebuild_rs_task(this);
1469         assert(check_heap_region_claim_values(
1470                HeapRegion::InitialClaimValue), "sanity check");
1471         assert(UseDynamicNumberOfGCThreads ||
1472                workers()->active_workers() == workers()->total_workers(),
1473                "Unless dynamic should use total workers");
1474         // Use the most recent number of  active workers
1475         assert(workers()->active_workers() > 0,
1476                "Active workers not properly set");
1477         set_par_threads(workers()->active_workers());
1478         workers()->run_task(&rebuild_rs_task);
1479         set_par_threads(0);
1480         assert(check_heap_region_claim_values(
1481                HeapRegion::RebuildRSClaimValue), "sanity check");
1482         reset_heap_region_claim_values();
1483       } else {
1484         RebuildRSOutOfRegionClosure rebuild_rs(this);
1485         heap_region_iterate(&rebuild_rs);
1486       }
1487 
1488       // Rebuild the strong code root lists for each region
1489       rebuild_strong_code_roots();
1490 
1491       if (true) { // FIXME
1492         MetaspaceGC::compute_new_size();
1493       }
1494 
1495 #ifdef TRACESPINNING
1496       ParallelTaskTerminator::print_termination_counts();
1497 #endif
1498 
1499       // Discard all rset updates
1500       JavaThread::dirty_card_queue_set().abandon_logs();
1501       assert(!G1DeferredRSUpdate
1502              || (G1DeferredRSUpdate &&
1503                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1504 
1505       _young_list->reset_sampled_info();
1506       // At this point there should be no regions in the
1507       // entire heap tagged as young.
1508       assert(check_young_list_empty(true /* check_heap */),
1509              "young list should be empty at this point");
1510 
1511       // Update the number of full collections that have been completed.
1512       increment_old_marking_cycles_completed(false /* concurrent */);
1513 
1514       _hrs.verify_optional();
1515       verify_region_sets_optional();
1516 
1517       verify_after_gc();
1518 
1519       // Start a new incremental collection set for the next pause
1520       assert(g1_policy()->collection_set() == NULL, "must be");
1521       g1_policy()->start_incremental_cset_building();
1522 
1523       // Clear the _cset_fast_test bitmap in anticipation of adding
1524       // regions to the incremental collection set for the next
1525       // evacuation pause.
1526       clear_cset_fast_test();
1527 
1528       init_mutator_alloc_region();
1529 
1530       double end = os::elapsedTime();
1531       g1_policy()->record_full_collection_end();
1532 
1533       if (G1Log::fine()) {
1534         g1_policy()->print_heap_transition();
1535       }
1536 
1537       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1538       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1539       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1540       // before any GC notifications are raised.
1541       g1mm()->update_sizes();
1542 
1543       gc_epilogue(true);
1544     }
1545 
1546     if (G1Log::finer()) {
1547       g1_policy()->print_detailed_heap_transition(true /* full */);
1548     }
1549 
1550     print_heap_after_gc();
1551     trace_heap_after_gc(gc_tracer);
1552 
1553     post_full_gc_dump(gc_timer);
1554 
1555     gc_timer->register_gc_end(os::elapsed_counter());
1556     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1557   }
1558 
1559   return true;
1560 }
1561 
1562 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1563   // do_collection() will return whether it succeeded in performing
1564   // the GC. Currently, there is no facility on the
1565   // do_full_collection() API to notify the caller than the collection
1566   // did not succeed (e.g., because it was locked out by the GC
1567   // locker). So, right now, we'll ignore the return value.
1568   bool dummy = do_collection(true,                /* explicit_gc */
1569                              clear_all_soft_refs,
1570                              0                    /* word_size */);
1571 }
1572 
1573 // This code is mostly copied from TenuredGeneration.
1574 void
1575 G1CollectedHeap::
1576 resize_if_necessary_after_full_collection(size_t word_size) {
1577   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1578 
1579   // Include the current allocation, if any, and bytes that will be
1580   // pre-allocated to support collections, as "used".
1581   const size_t used_after_gc = used();
1582   const size_t capacity_after_gc = capacity();
1583   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1584 
1585   // This is enforced in arguments.cpp.
1586   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1587          "otherwise the code below doesn't make sense");
1588 
1589   // We don't have floating point command-line arguments
1590   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1591   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1592   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1593   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1594 
1595   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1596   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1597 
1598   // We have to be careful here as these two calculations can overflow
1599   // 32-bit size_t's.
1600   double used_after_gc_d = (double) used_after_gc;
1601   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1602   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1603 
1604   // Let's make sure that they are both under the max heap size, which
1605   // by default will make them fit into a size_t.
1606   double desired_capacity_upper_bound = (double) max_heap_size;
1607   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1608                                     desired_capacity_upper_bound);
1609   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1610                                     desired_capacity_upper_bound);
1611 
1612   // We can now safely turn them into size_t's.
1613   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1614   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1615 
1616   // This assert only makes sense here, before we adjust them
1617   // with respect to the min and max heap size.
1618   assert(minimum_desired_capacity <= maximum_desired_capacity,
1619          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1620                  "maximum_desired_capacity = "SIZE_FORMAT,
1621                  minimum_desired_capacity, maximum_desired_capacity));
1622 
1623   // Should not be greater than the heap max size. No need to adjust
1624   // it with respect to the heap min size as it's a lower bound (i.e.,
1625   // we'll try to make the capacity larger than it, not smaller).
1626   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1627   // Should not be less than the heap min size. No need to adjust it
1628   // with respect to the heap max size as it's an upper bound (i.e.,
1629   // we'll try to make the capacity smaller than it, not greater).
1630   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1631 
1632   if (capacity_after_gc < minimum_desired_capacity) {
1633     // Don't expand unless it's significant
1634     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1635     ergo_verbose4(ErgoHeapSizing,
1636                   "attempt heap expansion",
1637                   ergo_format_reason("capacity lower than "
1638                                      "min desired capacity after Full GC")
1639                   ergo_format_byte("capacity")
1640                   ergo_format_byte("occupancy")
1641                   ergo_format_byte_perc("min desired capacity"),
1642                   capacity_after_gc, used_after_gc,
1643                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1644     expand(expand_bytes);
1645 
1646     // No expansion, now see if we want to shrink
1647   } else if (capacity_after_gc > maximum_desired_capacity) {
1648     // Capacity too large, compute shrinking size
1649     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1650     ergo_verbose4(ErgoHeapSizing,
1651                   "attempt heap shrinking",
1652                   ergo_format_reason("capacity higher than "
1653                                      "max desired capacity after Full GC")
1654                   ergo_format_byte("capacity")
1655                   ergo_format_byte("occupancy")
1656                   ergo_format_byte_perc("max desired capacity"),
1657                   capacity_after_gc, used_after_gc,
1658                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1659     shrink(shrink_bytes);
1660   }
1661 }
1662 
1663 
1664 HeapWord*
1665 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1666                                            bool* succeeded) {
1667   assert_at_safepoint(true /* should_be_vm_thread */);
1668 
1669   *succeeded = true;
1670   // Let's attempt the allocation first.
1671   HeapWord* result =
1672     attempt_allocation_at_safepoint(word_size,
1673                                  false /* expect_null_mutator_alloc_region */);
1674   if (result != NULL) {
1675     assert(*succeeded, "sanity");
1676     return result;
1677   }
1678 
1679   // In a G1 heap, we're supposed to keep allocation from failing by
1680   // incremental pauses.  Therefore, at least for now, we'll favor
1681   // expansion over collection.  (This might change in the future if we can
1682   // do something smarter than full collection to satisfy a failed alloc.)
1683   result = expand_and_allocate(word_size);
1684   if (result != NULL) {
1685     assert(*succeeded, "sanity");
1686     return result;
1687   }
1688 
1689   // Expansion didn't work, we'll try to do a Full GC.
1690   bool gc_succeeded = do_collection(false, /* explicit_gc */
1691                                     false, /* clear_all_soft_refs */
1692                                     word_size);
1693   if (!gc_succeeded) {
1694     *succeeded = false;
1695     return NULL;
1696   }
1697 
1698   // Retry the allocation
1699   result = attempt_allocation_at_safepoint(word_size,
1700                                   true /* expect_null_mutator_alloc_region */);
1701   if (result != NULL) {
1702     assert(*succeeded, "sanity");
1703     return result;
1704   }
1705 
1706   // Then, try a Full GC that will collect all soft references.
1707   gc_succeeded = do_collection(false, /* explicit_gc */
1708                                true,  /* clear_all_soft_refs */
1709                                word_size);
1710   if (!gc_succeeded) {
1711     *succeeded = false;
1712     return NULL;
1713   }
1714 
1715   // Retry the allocation once more
1716   result = attempt_allocation_at_safepoint(word_size,
1717                                   true /* expect_null_mutator_alloc_region */);
1718   if (result != NULL) {
1719     assert(*succeeded, "sanity");
1720     return result;
1721   }
1722 
1723   assert(!collector_policy()->should_clear_all_soft_refs(),
1724          "Flag should have been handled and cleared prior to this point");
1725 
1726   // What else?  We might try synchronous finalization later.  If the total
1727   // space available is large enough for the allocation, then a more
1728   // complete compaction phase than we've tried so far might be
1729   // appropriate.
1730   assert(*succeeded, "sanity");
1731   return NULL;
1732 }
1733 
1734 // Attempting to expand the heap sufficiently
1735 // to support an allocation of the given "word_size".  If
1736 // successful, perform the allocation and return the address of the
1737 // allocated block, or else "NULL".
1738 
1739 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1740   assert_at_safepoint(true /* should_be_vm_thread */);
1741 
1742   verify_region_sets_optional();
1743 
1744   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1745   ergo_verbose1(ErgoHeapSizing,
1746                 "attempt heap expansion",
1747                 ergo_format_reason("allocation request failed")
1748                 ergo_format_byte("allocation request"),
1749                 word_size * HeapWordSize);
1750   if (expand(expand_bytes)) {
1751     _hrs.verify_optional();
1752     verify_region_sets_optional();
1753     return attempt_allocation_at_safepoint(word_size,
1754                                  false /* expect_null_mutator_alloc_region */);
1755   }
1756   return NULL;
1757 }
1758 
1759 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1760                                              HeapWord* new_end) {
1761   assert(old_end != new_end, "don't call this otherwise");
1762   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1763 
1764   // Update the committed mem region.
1765   _g1_committed.set_end(new_end);
1766   // Tell the card table about the update.
1767   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1768   // Tell the BOT about the update.
1769   _bot_shared->resize(_g1_committed.word_size());
1770   // Tell the hot card cache about the update
1771   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1772 }
1773 
1774 bool G1CollectedHeap::expand(size_t expand_bytes) {
1775   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1776   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1777                                        HeapRegion::GrainBytes);
1778   ergo_verbose2(ErgoHeapSizing,
1779                 "expand the heap",
1780                 ergo_format_byte("requested expansion amount")
1781                 ergo_format_byte("attempted expansion amount"),
1782                 expand_bytes, aligned_expand_bytes);
1783 
1784   if (_g1_storage.uncommitted_size() == 0) {
1785     ergo_verbose0(ErgoHeapSizing,
1786                       "did not expand the heap",
1787                       ergo_format_reason("heap already fully expanded"));
1788     return false;
1789   }
1790 
1791   // First commit the memory.
1792   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1793   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1794   if (successful) {
1795     // Then propagate this update to the necessary data structures.
1796     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1797     update_committed_space(old_end, new_end);
1798 
1799     FreeRegionList expansion_list("Local Expansion List");
1800     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1801     assert(mr.start() == old_end, "post-condition");
1802     // mr might be a smaller region than what was requested if
1803     // expand_by() was unable to allocate the HeapRegion instances
1804     assert(mr.end() <= new_end, "post-condition");
1805 
1806     size_t actual_expand_bytes = mr.byte_size();
1807     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1808     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1809            "post-condition");
1810     if (actual_expand_bytes < aligned_expand_bytes) {
1811       // We could not expand _hrs to the desired size. In this case we
1812       // need to shrink the committed space accordingly.
1813       assert(mr.end() < new_end, "invariant");
1814 
1815       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1816       // First uncommit the memory.
1817       _g1_storage.shrink_by(diff_bytes);
1818       // Then propagate this update to the necessary data structures.
1819       update_committed_space(new_end, mr.end());
1820     }
1821     _free_list.add_as_tail(&expansion_list);
1822 
1823     if (_hr_printer.is_active()) {
1824       HeapWord* curr = mr.start();
1825       while (curr < mr.end()) {
1826         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1827         _hr_printer.commit(curr, curr_end);
1828         curr = curr_end;
1829       }
1830       assert(curr == mr.end(), "post-condition");
1831     }
1832     g1_policy()->record_new_heap_size(n_regions());
1833   } else {
1834     ergo_verbose0(ErgoHeapSizing,
1835                   "did not expand the heap",
1836                   ergo_format_reason("heap expansion operation failed"));
1837     // The expansion of the virtual storage space was unsuccessful.
1838     // Let's see if it was because we ran out of swap.
1839     if (G1ExitOnExpansionFailure &&
1840         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1841       // We had head room...
1842       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1843     }
1844   }
1845   return successful;
1846 }
1847 
1848 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1849   size_t aligned_shrink_bytes =
1850     ReservedSpace::page_align_size_down(shrink_bytes);
1851   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1852                                          HeapRegion::GrainBytes);
1853   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1854 
1855   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1856   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1857   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1858 
1859   ergo_verbose3(ErgoHeapSizing,
1860                 "shrink the heap",
1861                 ergo_format_byte("requested shrinking amount")
1862                 ergo_format_byte("aligned shrinking amount")
1863                 ergo_format_byte("attempted shrinking amount"),
1864                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1865   if (num_regions_removed > 0) {
1866     _g1_storage.shrink_by(shrunk_bytes);
1867     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1868 
1869     if (_hr_printer.is_active()) {
1870       HeapWord* curr = old_end;
1871       while (curr > new_end) {
1872         HeapWord* curr_end = curr;
1873         curr -= HeapRegion::GrainWords;
1874         _hr_printer.uncommit(curr, curr_end);
1875       }
1876     }
1877 
1878     _expansion_regions += num_regions_removed;
1879     update_committed_space(old_end, new_end);
1880     HeapRegionRemSet::shrink_heap(n_regions());
1881     g1_policy()->record_new_heap_size(n_regions());
1882   } else {
1883     ergo_verbose0(ErgoHeapSizing,
1884                   "did not shrink the heap",
1885                   ergo_format_reason("heap shrinking operation failed"));
1886   }
1887 }
1888 
1889 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1890   verify_region_sets_optional();
1891 
1892   // We should only reach here at the end of a Full GC which means we
1893   // should not not be holding to any GC alloc regions. The method
1894   // below will make sure of that and do any remaining clean up.
1895   abandon_gc_alloc_regions();
1896 
1897   // Instead of tearing down / rebuilding the free lists here, we
1898   // could instead use the remove_all_pending() method on free_list to
1899   // remove only the ones that we need to remove.
1900   tear_down_region_sets(true /* free_list_only */);
1901   shrink_helper(shrink_bytes);
1902   rebuild_region_sets(true /* free_list_only */);
1903 
1904   _hrs.verify_optional();
1905   verify_region_sets_optional();
1906 }
1907 
1908 // Public methods.
1909 
1910 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1911 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1912 #endif // _MSC_VER
1913 
1914 
1915 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1916   SharedHeap(policy_),
1917   _g1_policy(policy_),
1918   _dirty_card_queue_set(false),
1919   _into_cset_dirty_card_queue_set(false),
1920   _is_alive_closure_cm(this),
1921   _is_alive_closure_stw(this),
1922   _ref_processor_cm(NULL),
1923   _ref_processor_stw(NULL),
1924   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1925   _bot_shared(NULL),
1926   _evac_failure_scan_stack(NULL),
1927   _mark_in_progress(false),
1928   _cg1r(NULL), _summary_bytes_used(0),
1929   _g1mm(NULL),
1930   _refine_cte_cl(NULL),
1931   _full_collection(false),
1932   _free_list("Master Free List"),
1933   _secondary_free_list("Secondary Free List"),
1934   _old_set("Old Set"),
1935   _humongous_set("Master Humongous Set"),
1936   _free_regions_coming(false),
1937   _young_list(new YoungList(this)),
1938   _gc_time_stamp(0),
1939   _retained_old_gc_alloc_region(NULL),
1940   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1941   _old_plab_stats(OldPLABSize, PLABWeight),
1942   _expand_heap_after_alloc_failure(true),
1943   _surviving_young_words(NULL),
1944   _old_marking_cycles_started(0),
1945   _old_marking_cycles_completed(0),
1946   _concurrent_cycle_started(false),
1947   _in_cset_fast_test(NULL),
1948   _in_cset_fast_test_base(NULL),
1949   _dirty_cards_region_list(NULL),
1950   _worker_cset_start_region(NULL),
1951   _worker_cset_start_region_time_stamp(NULL),
1952   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1953   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1954   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1955   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1956 
1957   _g1h = this;
1958   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1959     vm_exit_during_initialization("Failed necessary allocation.");
1960   }
1961 
1962   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1963 
1964   int n_queues = MAX2((int)ParallelGCThreads, 1);
1965   _task_queues = new RefToScanQueueSet(n_queues);
1966 
1967   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1968   assert(n_rem_sets > 0, "Invariant.");
1969 
1970   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1971   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1972   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1973 
1974   for (int i = 0; i < n_queues; i++) {
1975     RefToScanQueue* q = new RefToScanQueue();
1976     q->initialize();
1977     _task_queues->register_queue(i, q);
1978     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1979   }
1980   clear_cset_start_regions();
1981 
1982   // Initialize the G1EvacuationFailureALot counters and flags.
1983   NOT_PRODUCT(reset_evacuation_should_fail();)
1984 
1985   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1986 }
1987 
1988 jint G1CollectedHeap::initialize() {
1989   CollectedHeap::pre_initialize();
1990   os::enable_vtime();
1991 
1992   G1Log::init();
1993 
1994   // Necessary to satisfy locking discipline assertions.
1995 
1996   MutexLocker x(Heap_lock);
1997 
1998   // We have to initialize the printer before committing the heap, as
1999   // it will be used then.
2000   _hr_printer.set_active(G1PrintHeapRegions);
2001 
2002   // While there are no constraints in the GC code that HeapWordSize
2003   // be any particular value, there are multiple other areas in the
2004   // system which believe this to be true (e.g. oop->object_size in some
2005   // cases incorrectly returns the size in wordSize units rather than
2006   // HeapWordSize).
2007   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2008 
2009   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2010   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2011   size_t heap_alignment = collector_policy()->heap_alignment();
2012 
2013   // Ensure that the sizes are properly aligned.
2014   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2015   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2016   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2017 
2018   _cg1r = new ConcurrentG1Refine(this);
2019 
2020   // Reserve the maximum.
2021 
2022   // When compressed oops are enabled, the preferred heap base
2023   // is calculated by subtracting the requested size from the
2024   // 32Gb boundary and using the result as the base address for
2025   // heap reservation. If the requested size is not aligned to
2026   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2027   // into the ReservedHeapSpace constructor) then the actual
2028   // base of the reserved heap may end up differing from the
2029   // address that was requested (i.e. the preferred heap base).
2030   // If this happens then we could end up using a non-optimal
2031   // compressed oops mode.
2032 
2033   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2034                                                  heap_alignment);
2035 
2036   // It is important to do this in a way such that concurrent readers can't
2037   // temporarily think something is in the heap.  (I've actually seen this
2038   // happen in asserts: DLD.)
2039   _reserved.set_word_size(0);
2040   _reserved.set_start((HeapWord*)heap_rs.base());
2041   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2042 
2043   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2044 
2045   // Create the gen rem set (and barrier set) for the entire reserved region.
2046   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2047   set_barrier_set(rem_set()->bs());
2048   if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2049     vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2050     return JNI_ENOMEM;
2051   }
2052 
2053   // Also create a G1 rem set.
2054   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2055 
2056   // Carve out the G1 part of the heap.
2057 
2058   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2059   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2060                            g1_rs.size()/HeapWordSize);
2061 
2062   _g1_storage.initialize(g1_rs, 0);
2063   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2064   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2065                   (HeapWord*) _g1_reserved.end());
2066   assert(_hrs.max_length() == _expansion_regions,
2067          err_msg("max length: %u expansion regions: %u",
2068                  _hrs.max_length(), _expansion_regions));
2069 
2070   // Do later initialization work for concurrent refinement.
2071   _cg1r->init();
2072 
2073   // 6843694 - ensure that the maximum region index can fit
2074   // in the remembered set structures.
2075   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2076   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2077 
2078   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2079   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2080   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2081             "too many cards per region");
2082 
2083   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2084 
2085   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2086                                              heap_word_size(init_byte_size));
2087 
2088   _g1h = this;
2089 
2090   _in_cset_fast_test_length = max_regions();
2091   _in_cset_fast_test_base =
2092                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2093 
2094   // We're biasing _in_cset_fast_test to avoid subtracting the
2095   // beginning of the heap every time we want to index; basically
2096   // it's the same with what we do with the card table.
2097   _in_cset_fast_test = _in_cset_fast_test_base -
2098                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2099 
2100   // Clear the _cset_fast_test bitmap in anticipation of adding
2101   // regions to the incremental collection set for the first
2102   // evacuation pause.
2103   clear_cset_fast_test();
2104 
2105   // Create the ConcurrentMark data structure and thread.
2106   // (Must do this late, so that "max_regions" is defined.)
2107   _cm = new ConcurrentMark(this, heap_rs);
2108   if (_cm == NULL || !_cm->completed_initialization()) {
2109     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2110     return JNI_ENOMEM;
2111   }
2112   _cmThread = _cm->cmThread();
2113 
2114   // Initialize the from_card cache structure of HeapRegionRemSet.
2115   HeapRegionRemSet::init_heap(max_regions());
2116 
2117   // Now expand into the initial heap size.
2118   if (!expand(init_byte_size)) {
2119     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2120     return JNI_ENOMEM;
2121   }
2122 
2123   // Perform any initialization actions delegated to the policy.
2124   g1_policy()->init();
2125 
2126   _refine_cte_cl =
2127     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2128                                     g1_rem_set(),
2129                                     concurrent_g1_refine());
2130   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2131 
2132   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2133                                                SATB_Q_FL_lock,
2134                                                G1SATBProcessCompletedThreshold,
2135                                                Shared_SATB_Q_lock);
2136 
2137   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2138                                                 DirtyCardQ_FL_lock,
2139                                                 concurrent_g1_refine()->yellow_zone(),
2140                                                 concurrent_g1_refine()->red_zone(),
2141                                                 Shared_DirtyCardQ_lock);
2142 
2143   if (G1DeferredRSUpdate) {
2144     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2145                                       DirtyCardQ_FL_lock,
2146                                       -1, // never trigger processing
2147                                       -1, // no limit on length
2148                                       Shared_DirtyCardQ_lock,
2149                                       &JavaThread::dirty_card_queue_set());
2150   }
2151 
2152   // Initialize the card queue set used to hold cards containing
2153   // references into the collection set.
2154   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2155                                              DirtyCardQ_FL_lock,
2156                                              -1, // never trigger processing
2157                                              -1, // no limit on length
2158                                              Shared_DirtyCardQ_lock,
2159                                              &JavaThread::dirty_card_queue_set());
2160 
2161   // In case we're keeping closure specialization stats, initialize those
2162   // counts and that mechanism.
2163   SpecializationStats::clear();
2164 
2165   // Here we allocate the dummy full region that is required by the
2166   // G1AllocRegion class. If we don't pass an address in the reserved
2167   // space here, lots of asserts fire.
2168 
2169   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2170                                              _g1_reserved.start());
2171   // We'll re-use the same region whether the alloc region will
2172   // require BOT updates or not and, if it doesn't, then a non-young
2173   // region will complain that it cannot support allocations without
2174   // BOT updates. So we'll tag the dummy region as young to avoid that.
2175   dummy_region->set_young();
2176   // Make sure it's full.
2177   dummy_region->set_top(dummy_region->end());
2178   G1AllocRegion::setup(this, dummy_region);
2179 
2180   init_mutator_alloc_region();
2181 
2182   // Do create of the monitoring and management support so that
2183   // values in the heap have been properly initialized.
2184   _g1mm = new G1MonitoringSupport(this);
2185 
2186   return JNI_OK;
2187 }
2188 
2189 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2190   return HeapRegion::max_region_size();
2191 }
2192 
2193 void G1CollectedHeap::ref_processing_init() {
2194   // Reference processing in G1 currently works as follows:
2195   //
2196   // * There are two reference processor instances. One is
2197   //   used to record and process discovered references
2198   //   during concurrent marking; the other is used to
2199   //   record and process references during STW pauses
2200   //   (both full and incremental).
2201   // * Both ref processors need to 'span' the entire heap as
2202   //   the regions in the collection set may be dotted around.
2203   //
2204   // * For the concurrent marking ref processor:
2205   //   * Reference discovery is enabled at initial marking.
2206   //   * Reference discovery is disabled and the discovered
2207   //     references processed etc during remarking.
2208   //   * Reference discovery is MT (see below).
2209   //   * Reference discovery requires a barrier (see below).
2210   //   * Reference processing may or may not be MT
2211   //     (depending on the value of ParallelRefProcEnabled
2212   //     and ParallelGCThreads).
2213   //   * A full GC disables reference discovery by the CM
2214   //     ref processor and abandons any entries on it's
2215   //     discovered lists.
2216   //
2217   // * For the STW processor:
2218   //   * Non MT discovery is enabled at the start of a full GC.
2219   //   * Processing and enqueueing during a full GC is non-MT.
2220   //   * During a full GC, references are processed after marking.
2221   //
2222   //   * Discovery (may or may not be MT) is enabled at the start
2223   //     of an incremental evacuation pause.
2224   //   * References are processed near the end of a STW evacuation pause.
2225   //   * For both types of GC:
2226   //     * Discovery is atomic - i.e. not concurrent.
2227   //     * Reference discovery will not need a barrier.
2228 
2229   SharedHeap::ref_processing_init();
2230   MemRegion mr = reserved_region();
2231 
2232   // Concurrent Mark ref processor
2233   _ref_processor_cm =
2234     new ReferenceProcessor(mr,    // span
2235                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2236                                 // mt processing
2237                            (int) ParallelGCThreads,
2238                                 // degree of mt processing
2239                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2240                                 // mt discovery
2241                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2242                                 // degree of mt discovery
2243                            false,
2244                                 // Reference discovery is not atomic
2245                            &_is_alive_closure_cm,
2246                                 // is alive closure
2247                                 // (for efficiency/performance)
2248                            true);
2249                                 // Setting next fields of discovered
2250                                 // lists requires a barrier.
2251 
2252   // STW ref processor
2253   _ref_processor_stw =
2254     new ReferenceProcessor(mr,    // span
2255                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2256                                 // mt processing
2257                            MAX2((int)ParallelGCThreads, 1),
2258                                 // degree of mt processing
2259                            (ParallelGCThreads > 1),
2260                                 // mt discovery
2261                            MAX2((int)ParallelGCThreads, 1),
2262                                 // degree of mt discovery
2263                            true,
2264                                 // Reference discovery is atomic
2265                            &_is_alive_closure_stw,
2266                                 // is alive closure
2267                                 // (for efficiency/performance)
2268                            false);
2269                                 // Setting next fields of discovered
2270                                 // lists requires a barrier.
2271 }
2272 
2273 size_t G1CollectedHeap::capacity() const {
2274   return _g1_committed.byte_size();
2275 }
2276 
2277 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2278   assert(!hr->continuesHumongous(), "pre-condition");
2279   hr->reset_gc_time_stamp();
2280   if (hr->startsHumongous()) {
2281     uint first_index = hr->hrs_index() + 1;
2282     uint last_index = hr->last_hc_index();
2283     for (uint i = first_index; i < last_index; i += 1) {
2284       HeapRegion* chr = region_at(i);
2285       assert(chr->continuesHumongous(), "sanity");
2286       chr->reset_gc_time_stamp();
2287     }
2288   }
2289 }
2290 
2291 #ifndef PRODUCT
2292 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2293 private:
2294   unsigned _gc_time_stamp;
2295   bool _failures;
2296 
2297 public:
2298   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2299     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2300 
2301   virtual bool doHeapRegion(HeapRegion* hr) {
2302     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2303     if (_gc_time_stamp != region_gc_time_stamp) {
2304       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2305                              "expected %d", HR_FORMAT_PARAMS(hr),
2306                              region_gc_time_stamp, _gc_time_stamp);
2307       _failures = true;
2308     }
2309     return false;
2310   }
2311 
2312   bool failures() { return _failures; }
2313 };
2314 
2315 void G1CollectedHeap::check_gc_time_stamps() {
2316   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2317   heap_region_iterate(&cl);
2318   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2319 }
2320 #endif // PRODUCT
2321 
2322 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2323                                                  DirtyCardQueue* into_cset_dcq,
2324                                                  bool concurrent,
2325                                                  int worker_i) {
2326   // Clean cards in the hot card cache
2327   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2328   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2329 
2330   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2331   int n_completed_buffers = 0;
2332   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2333     n_completed_buffers++;
2334   }
2335   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2336   dcqs.clear_n_completed_buffers();
2337   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2338 }
2339 
2340 
2341 // Computes the sum of the storage used by the various regions.
2342 
2343 size_t G1CollectedHeap::used() const {
2344   assert(Heap_lock->owner() != NULL,
2345          "Should be owned on this thread's behalf.");
2346   size_t result = _summary_bytes_used;
2347   // Read only once in case it is set to NULL concurrently
2348   HeapRegion* hr = _mutator_alloc_region.get();
2349   if (hr != NULL)
2350     result += hr->used();
2351   return result;
2352 }
2353 
2354 size_t G1CollectedHeap::used_unlocked() const {
2355   size_t result = _summary_bytes_used;
2356   return result;
2357 }
2358 
2359 class SumUsedClosure: public HeapRegionClosure {
2360   size_t _used;
2361 public:
2362   SumUsedClosure() : _used(0) {}
2363   bool doHeapRegion(HeapRegion* r) {
2364     if (!r->continuesHumongous()) {
2365       _used += r->used();
2366     }
2367     return false;
2368   }
2369   size_t result() { return _used; }
2370 };
2371 
2372 size_t G1CollectedHeap::recalculate_used() const {
2373   SumUsedClosure blk;
2374   heap_region_iterate(&blk);
2375   return blk.result();
2376 }
2377 
2378 size_t G1CollectedHeap::unsafe_max_alloc() {
2379   if (free_regions() > 0) return HeapRegion::GrainBytes;
2380   // otherwise, is there space in the current allocation region?
2381 
2382   // We need to store the current allocation region in a local variable
2383   // here. The problem is that this method doesn't take any locks and
2384   // there may be other threads which overwrite the current allocation
2385   // region field. attempt_allocation(), for example, sets it to NULL
2386   // and this can happen *after* the NULL check here but before the call
2387   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2388   // to be a problem in the optimized build, since the two loads of the
2389   // current allocation region field are optimized away.
2390   HeapRegion* hr = _mutator_alloc_region.get();
2391   if (hr == NULL) {
2392     return 0;
2393   }
2394   return hr->free();
2395 }
2396 
2397 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2398   switch (cause) {
2399     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2400     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2401     case GCCause::_g1_humongous_allocation: return true;
2402     default:                                return false;
2403   }
2404 }
2405 
2406 #ifndef PRODUCT
2407 void G1CollectedHeap::allocate_dummy_regions() {
2408   // Let's fill up most of the region
2409   size_t word_size = HeapRegion::GrainWords - 1024;
2410   // And as a result the region we'll allocate will be humongous.
2411   guarantee(isHumongous(word_size), "sanity");
2412 
2413   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2414     // Let's use the existing mechanism for the allocation
2415     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2416     if (dummy_obj != NULL) {
2417       MemRegion mr(dummy_obj, word_size);
2418       CollectedHeap::fill_with_object(mr);
2419     } else {
2420       // If we can't allocate once, we probably cannot allocate
2421       // again. Let's get out of the loop.
2422       break;
2423     }
2424   }
2425 }
2426 #endif // !PRODUCT
2427 
2428 void G1CollectedHeap::increment_old_marking_cycles_started() {
2429   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2430     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2431     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2432     _old_marking_cycles_started, _old_marking_cycles_completed));
2433 
2434   _old_marking_cycles_started++;
2435 }
2436 
2437 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2438   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2439 
2440   // We assume that if concurrent == true, then the caller is a
2441   // concurrent thread that was joined the Suspendible Thread
2442   // Set. If there's ever a cheap way to check this, we should add an
2443   // assert here.
2444 
2445   // Given that this method is called at the end of a Full GC or of a
2446   // concurrent cycle, and those can be nested (i.e., a Full GC can
2447   // interrupt a concurrent cycle), the number of full collections
2448   // completed should be either one (in the case where there was no
2449   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2450   // behind the number of full collections started.
2451 
2452   // This is the case for the inner caller, i.e. a Full GC.
2453   assert(concurrent ||
2454          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2455          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2456          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2457                  "is inconsistent with _old_marking_cycles_completed = %u",
2458                  _old_marking_cycles_started, _old_marking_cycles_completed));
2459 
2460   // This is the case for the outer caller, i.e. the concurrent cycle.
2461   assert(!concurrent ||
2462          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2463          err_msg("for outer caller (concurrent cycle): "
2464                  "_old_marking_cycles_started = %u "
2465                  "is inconsistent with _old_marking_cycles_completed = %u",
2466                  _old_marking_cycles_started, _old_marking_cycles_completed));
2467 
2468   _old_marking_cycles_completed += 1;
2469 
2470   // We need to clear the "in_progress" flag in the CM thread before
2471   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2472   // is set) so that if a waiter requests another System.gc() it doesn't
2473   // incorrectly see that a marking cycle is still in progress.
2474   if (concurrent) {
2475     _cmThread->clear_in_progress();
2476   }
2477 
2478   // This notify_all() will ensure that a thread that called
2479   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2480   // and it's waiting for a full GC to finish will be woken up. It is
2481   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2482   FullGCCount_lock->notify_all();
2483 }
2484 
2485 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2486   _concurrent_cycle_started = true;
2487   _gc_timer_cm->register_gc_start(start_time);
2488 
2489   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2490   trace_heap_before_gc(_gc_tracer_cm);
2491 }
2492 
2493 void G1CollectedHeap::register_concurrent_cycle_end() {
2494   if (_concurrent_cycle_started) {
2495     if (_cm->has_aborted()) {
2496       _gc_tracer_cm->report_concurrent_mode_failure();
2497     }
2498 
2499     _gc_timer_cm->register_gc_end(os::elapsed_counter());
2500     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2501 
2502     _concurrent_cycle_started = false;
2503   }
2504 }
2505 
2506 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2507   if (_concurrent_cycle_started) {
2508     trace_heap_after_gc(_gc_tracer_cm);
2509   }
2510 }
2511 
2512 G1YCType G1CollectedHeap::yc_type() {
2513   bool is_young = g1_policy()->gcs_are_young();
2514   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2515   bool is_during_mark = mark_in_progress();
2516 
2517   if (is_initial_mark) {
2518     return InitialMark;
2519   } else if (is_during_mark) {
2520     return DuringMark;
2521   } else if (is_young) {
2522     return Normal;
2523   } else {
2524     return Mixed;
2525   }
2526 }
2527 
2528 void G1CollectedHeap::collect(GCCause::Cause cause) {
2529   assert_heap_not_locked();
2530 
2531   unsigned int gc_count_before;
2532   unsigned int old_marking_count_before;
2533   bool retry_gc;
2534 
2535   do {
2536     retry_gc = false;
2537 
2538     {
2539       MutexLocker ml(Heap_lock);
2540 
2541       // Read the GC count while holding the Heap_lock
2542       gc_count_before = total_collections();
2543       old_marking_count_before = _old_marking_cycles_started;
2544     }
2545 
2546     if (should_do_concurrent_full_gc(cause)) {
2547       // Schedule an initial-mark evacuation pause that will start a
2548       // concurrent cycle. We're setting word_size to 0 which means that
2549       // we are not requesting a post-GC allocation.
2550       VM_G1IncCollectionPause op(gc_count_before,
2551                                  0,     /* word_size */
2552                                  true,  /* should_initiate_conc_mark */
2553                                  g1_policy()->max_pause_time_ms(),
2554                                  cause);
2555 
2556       VMThread::execute(&op);
2557       if (!op.pause_succeeded()) {
2558         if (old_marking_count_before == _old_marking_cycles_started) {
2559           retry_gc = op.should_retry_gc();
2560         } else {
2561           // A Full GC happened while we were trying to schedule the
2562           // initial-mark GC. No point in starting a new cycle given
2563           // that the whole heap was collected anyway.
2564         }
2565 
2566         if (retry_gc) {
2567           if (GC_locker::is_active_and_needs_gc()) {
2568             GC_locker::stall_until_clear();
2569           }
2570         }
2571       }
2572     } else {
2573       if (cause == GCCause::_gc_locker
2574           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2575 
2576         // Schedule a standard evacuation pause. We're setting word_size
2577         // to 0 which means that we are not requesting a post-GC allocation.
2578         VM_G1IncCollectionPause op(gc_count_before,
2579                                    0,     /* word_size */
2580                                    false, /* should_initiate_conc_mark */
2581                                    g1_policy()->max_pause_time_ms(),
2582                                    cause);
2583         VMThread::execute(&op);
2584       } else {
2585         // Schedule a Full GC.
2586         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2587         VMThread::execute(&op);
2588       }
2589     }
2590   } while (retry_gc);
2591 }
2592 
2593 bool G1CollectedHeap::is_in(const void* p) const {
2594   if (_g1_committed.contains(p)) {
2595     // Given that we know that p is in the committed space,
2596     // heap_region_containing_raw() should successfully
2597     // return the containing region.
2598     HeapRegion* hr = heap_region_containing_raw(p);
2599     return hr->is_in(p);
2600   } else {
2601     return false;
2602   }
2603 }
2604 
2605 // Iteration functions.
2606 
2607 // Iterates an OopClosure over all ref-containing fields of objects
2608 // within a HeapRegion.
2609 
2610 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2611   MemRegion _mr;
2612   ExtendedOopClosure* _cl;
2613 public:
2614   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2615     : _mr(mr), _cl(cl) {}
2616   bool doHeapRegion(HeapRegion* r) {
2617     if (!r->continuesHumongous()) {
2618       r->oop_iterate(_cl);
2619     }
2620     return false;
2621   }
2622 };
2623 
2624 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2625   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2626   heap_region_iterate(&blk);
2627 }
2628 
2629 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2630   IterateOopClosureRegionClosure blk(mr, cl);
2631   heap_region_iterate(&blk);
2632 }
2633 
2634 // Iterates an ObjectClosure over all objects within a HeapRegion.
2635 
2636 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2637   ObjectClosure* _cl;
2638 public:
2639   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2640   bool doHeapRegion(HeapRegion* r) {
2641     if (! r->continuesHumongous()) {
2642       r->object_iterate(_cl);
2643     }
2644     return false;
2645   }
2646 };
2647 
2648 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2649   IterateObjectClosureRegionClosure blk(cl);
2650   heap_region_iterate(&blk);
2651 }
2652 
2653 // Calls a SpaceClosure on a HeapRegion.
2654 
2655 class SpaceClosureRegionClosure: public HeapRegionClosure {
2656   SpaceClosure* _cl;
2657 public:
2658   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2659   bool doHeapRegion(HeapRegion* r) {
2660     _cl->do_space(r);
2661     return false;
2662   }
2663 };
2664 
2665 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2666   SpaceClosureRegionClosure blk(cl);
2667   heap_region_iterate(&blk);
2668 }
2669 
2670 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2671   _hrs.iterate(cl);
2672 }
2673 
2674 void
2675 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2676                                                  uint worker_id,
2677                                                  uint no_of_par_workers,
2678                                                  jint claim_value) {
2679   const uint regions = n_regions();
2680   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2681                              no_of_par_workers :
2682                              1);
2683   assert(UseDynamicNumberOfGCThreads ||
2684          no_of_par_workers == workers()->total_workers(),
2685          "Non dynamic should use fixed number of workers");
2686   // try to spread out the starting points of the workers
2687   const HeapRegion* start_hr =
2688                         start_region_for_worker(worker_id, no_of_par_workers);
2689   const uint start_index = start_hr->hrs_index();
2690 
2691   // each worker will actually look at all regions
2692   for (uint count = 0; count < regions; ++count) {
2693     const uint index = (start_index + count) % regions;
2694     assert(0 <= index && index < regions, "sanity");
2695     HeapRegion* r = region_at(index);
2696     // we'll ignore "continues humongous" regions (we'll process them
2697     // when we come across their corresponding "start humongous"
2698     // region) and regions already claimed
2699     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2700       continue;
2701     }
2702     // OK, try to claim it
2703     if (r->claimHeapRegion(claim_value)) {
2704       // success!
2705       assert(!r->continuesHumongous(), "sanity");
2706       if (r->startsHumongous()) {
2707         // If the region is "starts humongous" we'll iterate over its
2708         // "continues humongous" first; in fact we'll do them
2709         // first. The order is important. In on case, calling the
2710         // closure on the "starts humongous" region might de-allocate
2711         // and clear all its "continues humongous" regions and, as a
2712         // result, we might end up processing them twice. So, we'll do
2713         // them first (notice: most closures will ignore them anyway) and
2714         // then we'll do the "starts humongous" region.
2715         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2716           HeapRegion* chr = region_at(ch_index);
2717 
2718           // if the region has already been claimed or it's not
2719           // "continues humongous" we're done
2720           if (chr->claim_value() == claim_value ||
2721               !chr->continuesHumongous()) {
2722             break;
2723           }
2724 
2725           // No one should have claimed it directly. We can given
2726           // that we claimed its "starts humongous" region.
2727           assert(chr->claim_value() != claim_value, "sanity");
2728           assert(chr->humongous_start_region() == r, "sanity");
2729 
2730           if (chr->claimHeapRegion(claim_value)) {
2731             // we should always be able to claim it; no one else should
2732             // be trying to claim this region
2733 
2734             bool res2 = cl->doHeapRegion(chr);
2735             assert(!res2, "Should not abort");
2736 
2737             // Right now, this holds (i.e., no closure that actually
2738             // does something with "continues humongous" regions
2739             // clears them). We might have to weaken it in the future,
2740             // but let's leave these two asserts here for extra safety.
2741             assert(chr->continuesHumongous(), "should still be the case");
2742             assert(chr->humongous_start_region() == r, "sanity");
2743           } else {
2744             guarantee(false, "we should not reach here");
2745           }
2746         }
2747       }
2748 
2749       assert(!r->continuesHumongous(), "sanity");
2750       bool res = cl->doHeapRegion(r);
2751       assert(!res, "Should not abort");
2752     }
2753   }
2754 }
2755 
2756 class ResetClaimValuesClosure: public HeapRegionClosure {
2757 public:
2758   bool doHeapRegion(HeapRegion* r) {
2759     r->set_claim_value(HeapRegion::InitialClaimValue);
2760     return false;
2761   }
2762 };
2763 
2764 void G1CollectedHeap::reset_heap_region_claim_values() {
2765   ResetClaimValuesClosure blk;
2766   heap_region_iterate(&blk);
2767 }
2768 
2769 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2770   ResetClaimValuesClosure blk;
2771   collection_set_iterate(&blk);
2772 }
2773 
2774 #ifdef ASSERT
2775 // This checks whether all regions in the heap have the correct claim
2776 // value. I also piggy-backed on this a check to ensure that the
2777 // humongous_start_region() information on "continues humongous"
2778 // regions is correct.
2779 
2780 class CheckClaimValuesClosure : public HeapRegionClosure {
2781 private:
2782   jint _claim_value;
2783   uint _failures;
2784   HeapRegion* _sh_region;
2785 
2786 public:
2787   CheckClaimValuesClosure(jint claim_value) :
2788     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2789   bool doHeapRegion(HeapRegion* r) {
2790     if (r->claim_value() != _claim_value) {
2791       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2792                              "claim value = %d, should be %d",
2793                              HR_FORMAT_PARAMS(r),
2794                              r->claim_value(), _claim_value);
2795       ++_failures;
2796     }
2797     if (!r->isHumongous()) {
2798       _sh_region = NULL;
2799     } else if (r->startsHumongous()) {
2800       _sh_region = r;
2801     } else if (r->continuesHumongous()) {
2802       if (r->humongous_start_region() != _sh_region) {
2803         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2804                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2805                                HR_FORMAT_PARAMS(r),
2806                                r->humongous_start_region(),
2807                                _sh_region);
2808         ++_failures;
2809       }
2810     }
2811     return false;
2812   }
2813   uint failures() { return _failures; }
2814 };
2815 
2816 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2817   CheckClaimValuesClosure cl(claim_value);
2818   heap_region_iterate(&cl);
2819   return cl.failures() == 0;
2820 }
2821 
2822 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2823 private:
2824   jint _claim_value;
2825   uint _failures;
2826 
2827 public:
2828   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2829     _claim_value(claim_value), _failures(0) { }
2830 
2831   uint failures() { return _failures; }
2832 
2833   bool doHeapRegion(HeapRegion* hr) {
2834     assert(hr->in_collection_set(), "how?");
2835     assert(!hr->isHumongous(), "H-region in CSet");
2836     if (hr->claim_value() != _claim_value) {
2837       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2838                              "claim value = %d, should be %d",
2839                              HR_FORMAT_PARAMS(hr),
2840                              hr->claim_value(), _claim_value);
2841       _failures += 1;
2842     }
2843     return false;
2844   }
2845 };
2846 
2847 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2848   CheckClaimValuesInCSetHRClosure cl(claim_value);
2849   collection_set_iterate(&cl);
2850   return cl.failures() == 0;
2851 }
2852 #endif // ASSERT
2853 
2854 // Clear the cached CSet starting regions and (more importantly)
2855 // the time stamps. Called when we reset the GC time stamp.
2856 void G1CollectedHeap::clear_cset_start_regions() {
2857   assert(_worker_cset_start_region != NULL, "sanity");
2858   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2859 
2860   int n_queues = MAX2((int)ParallelGCThreads, 1);
2861   for (int i = 0; i < n_queues; i++) {
2862     _worker_cset_start_region[i] = NULL;
2863     _worker_cset_start_region_time_stamp[i] = 0;
2864   }
2865 }
2866 
2867 // Given the id of a worker, obtain or calculate a suitable
2868 // starting region for iterating over the current collection set.
2869 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2870   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2871 
2872   HeapRegion* result = NULL;
2873   unsigned gc_time_stamp = get_gc_time_stamp();
2874 
2875   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2876     // Cached starting region for current worker was set
2877     // during the current pause - so it's valid.
2878     // Note: the cached starting heap region may be NULL
2879     // (when the collection set is empty).
2880     result = _worker_cset_start_region[worker_i];
2881     assert(result == NULL || result->in_collection_set(), "sanity");
2882     return result;
2883   }
2884 
2885   // The cached entry was not valid so let's calculate
2886   // a suitable starting heap region for this worker.
2887 
2888   // We want the parallel threads to start their collection
2889   // set iteration at different collection set regions to
2890   // avoid contention.
2891   // If we have:
2892   //          n collection set regions
2893   //          p threads
2894   // Then thread t will start at region floor ((t * n) / p)
2895 
2896   result = g1_policy()->collection_set();
2897   if (G1CollectedHeap::use_parallel_gc_threads()) {
2898     uint cs_size = g1_policy()->cset_region_length();
2899     uint active_workers = workers()->active_workers();
2900     assert(UseDynamicNumberOfGCThreads ||
2901              active_workers == workers()->total_workers(),
2902              "Unless dynamic should use total workers");
2903 
2904     uint end_ind   = (cs_size * worker_i) / active_workers;
2905     uint start_ind = 0;
2906 
2907     if (worker_i > 0 &&
2908         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2909       // Previous workers starting region is valid
2910       // so let's iterate from there
2911       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2912       result = _worker_cset_start_region[worker_i - 1];
2913     }
2914 
2915     for (uint i = start_ind; i < end_ind; i++) {
2916       result = result->next_in_collection_set();
2917     }
2918   }
2919 
2920   // Note: the calculated starting heap region may be NULL
2921   // (when the collection set is empty).
2922   assert(result == NULL || result->in_collection_set(), "sanity");
2923   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2924          "should be updated only once per pause");
2925   _worker_cset_start_region[worker_i] = result;
2926   OrderAccess::storestore();
2927   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2928   return result;
2929 }
2930 
2931 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2932                                                      uint no_of_par_workers) {
2933   uint worker_num =
2934            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2935   assert(UseDynamicNumberOfGCThreads ||
2936          no_of_par_workers == workers()->total_workers(),
2937          "Non dynamic should use fixed number of workers");
2938   const uint start_index = n_regions() * worker_i / worker_num;
2939   return region_at(start_index);
2940 }
2941 
2942 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2943   HeapRegion* r = g1_policy()->collection_set();
2944   while (r != NULL) {
2945     HeapRegion* next = r->next_in_collection_set();
2946     if (cl->doHeapRegion(r)) {
2947       cl->incomplete();
2948       return;
2949     }
2950     r = next;
2951   }
2952 }
2953 
2954 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2955                                                   HeapRegionClosure *cl) {
2956   if (r == NULL) {
2957     // The CSet is empty so there's nothing to do.
2958     return;
2959   }
2960 
2961   assert(r->in_collection_set(),
2962          "Start region must be a member of the collection set.");
2963   HeapRegion* cur = r;
2964   while (cur != NULL) {
2965     HeapRegion* next = cur->next_in_collection_set();
2966     if (cl->doHeapRegion(cur) && false) {
2967       cl->incomplete();
2968       return;
2969     }
2970     cur = next;
2971   }
2972   cur = g1_policy()->collection_set();
2973   while (cur != r) {
2974     HeapRegion* next = cur->next_in_collection_set();
2975     if (cl->doHeapRegion(cur) && false) {
2976       cl->incomplete();
2977       return;
2978     }
2979     cur = next;
2980   }
2981 }
2982 
2983 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2984   return n_regions() > 0 ? region_at(0) : NULL;
2985 }
2986 
2987 
2988 Space* G1CollectedHeap::space_containing(const void* addr) const {
2989   Space* res = heap_region_containing(addr);
2990   return res;
2991 }
2992 
2993 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2994   Space* sp = space_containing(addr);
2995   if (sp != NULL) {
2996     return sp->block_start(addr);
2997   }
2998   return NULL;
2999 }
3000 
3001 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3002   Space* sp = space_containing(addr);
3003   assert(sp != NULL, "block_size of address outside of heap");
3004   return sp->block_size(addr);
3005 }
3006 
3007 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3008   Space* sp = space_containing(addr);
3009   return sp->block_is_obj(addr);
3010 }
3011 
3012 bool G1CollectedHeap::supports_tlab_allocation() const {
3013   return true;
3014 }
3015 
3016 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3017   return HeapRegion::GrainBytes;
3018 }
3019 
3020 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3021   // Return the remaining space in the cur alloc region, but not less than
3022   // the min TLAB size.
3023 
3024   // Also, this value can be at most the humongous object threshold,
3025   // since we can't allow tlabs to grow big enough to accommodate
3026   // humongous objects.
3027 
3028   HeapRegion* hr = _mutator_alloc_region.get();
3029   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3030   if (hr == NULL) {
3031     return max_tlab_size;
3032   } else {
3033     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3034   }
3035 }
3036 
3037 size_t G1CollectedHeap::max_capacity() const {
3038   return _g1_reserved.byte_size();
3039 }
3040 
3041 jlong G1CollectedHeap::millis_since_last_gc() {
3042   // assert(false, "NYI");
3043   return 0;
3044 }
3045 
3046 void G1CollectedHeap::prepare_for_verify() {
3047   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3048     ensure_parsability(false);
3049   }
3050   g1_rem_set()->prepare_for_verify();
3051 }
3052 
3053 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3054                                               VerifyOption vo) {
3055   switch (vo) {
3056   case VerifyOption_G1UsePrevMarking:
3057     return hr->obj_allocated_since_prev_marking(obj);
3058   case VerifyOption_G1UseNextMarking:
3059     return hr->obj_allocated_since_next_marking(obj);
3060   case VerifyOption_G1UseMarkWord:
3061     return false;
3062   default:
3063     ShouldNotReachHere();
3064   }
3065   return false; // keep some compilers happy
3066 }
3067 
3068 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3069   switch (vo) {
3070   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3071   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3072   case VerifyOption_G1UseMarkWord:    return NULL;
3073   default:                            ShouldNotReachHere();
3074   }
3075   return NULL; // keep some compilers happy
3076 }
3077 
3078 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3079   switch (vo) {
3080   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3081   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3082   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3083   default:                            ShouldNotReachHere();
3084   }
3085   return false; // keep some compilers happy
3086 }
3087 
3088 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3089   switch (vo) {
3090   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3091   case VerifyOption_G1UseNextMarking: return "NTAMS";
3092   case VerifyOption_G1UseMarkWord:    return "NONE";
3093   default:                            ShouldNotReachHere();
3094   }
3095   return NULL; // keep some compilers happy
3096 }
3097 
3098 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3099 //       pass it as the perm_blk to SharedHeap::process_strong_roots.
3100 //       When process_strong_roots stop calling perm_blk->younger_refs_iterate
3101 //       we can change this closure to extend the simpler OopClosure.
3102 class VerifyRootsClosure: public OopsInGenClosure {
3103 private:
3104   G1CollectedHeap* _g1h;
3105   VerifyOption     _vo;
3106   bool             _failures;
3107 public:
3108   // _vo == UsePrevMarking -> use "prev" marking information,
3109   // _vo == UseNextMarking -> use "next" marking information,
3110   // _vo == UseMarkWord    -> use mark word from object header.
3111   VerifyRootsClosure(VerifyOption vo) :
3112     _g1h(G1CollectedHeap::heap()),
3113     _vo(vo),
3114     _failures(false) { }
3115 
3116   bool failures() { return _failures; }
3117 
3118   template <class T> void do_oop_nv(T* p) {
3119     T heap_oop = oopDesc::load_heap_oop(p);
3120     if (!oopDesc::is_null(heap_oop)) {
3121       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3122       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3123         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3124                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3125         if (_vo == VerifyOption_G1UseMarkWord) {
3126           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3127         }
3128         obj->print_on(gclog_or_tty);
3129         _failures = true;
3130       }
3131     }
3132   }
3133 
3134   void do_oop(oop* p)       { do_oop_nv(p); }
3135   void do_oop(narrowOop* p) { do_oop_nv(p); }
3136 };
3137 
3138 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3139   G1CollectedHeap* _g1h;
3140   OopClosure* _root_cl;
3141   nmethod* _nm;
3142   VerifyOption _vo;
3143   bool _failures;
3144 
3145   template <class T> void do_oop_work(T* p) {
3146     // First verify that this root is live
3147     _root_cl->do_oop(p);
3148 
3149     if (!G1VerifyHeapRegionCodeRoots) {
3150       // We're not verifying the code roots attached to heap region.
3151       return;
3152     }
3153 
3154     // Don't check the code roots during marking verification in a full GC
3155     if (_vo == VerifyOption_G1UseMarkWord) {
3156       return;
3157     }
3158 
3159     // Now verify that the current nmethod (which contains p) is
3160     // in the code root list of the heap region containing the
3161     // object referenced by p.
3162 
3163     T heap_oop = oopDesc::load_heap_oop(p);
3164     if (!oopDesc::is_null(heap_oop)) {
3165       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3166 
3167       // Now fetch the region containing the object
3168       HeapRegion* hr = _g1h->heap_region_containing(obj);
3169       HeapRegionRemSet* hrrs = hr->rem_set();
3170       // Verify that the strong code root list for this region
3171       // contains the nmethod
3172       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3173         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3174                               "from nmethod "PTR_FORMAT" not in strong "
3175                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3176                               p, _nm, hr->bottom(), hr->end());
3177         _failures = true;
3178       }
3179     }
3180   }
3181 
3182 public:
3183   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3184     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3185 
3186   void do_oop(oop* p) { do_oop_work(p); }
3187   void do_oop(narrowOop* p) { do_oop_work(p); }
3188 
3189   void set_nmethod(nmethod* nm) { _nm = nm; }
3190   bool failures() { return _failures; }
3191 };
3192 
3193 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3194   G1VerifyCodeRootOopClosure* _oop_cl;
3195 
3196 public:
3197   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3198     _oop_cl(oop_cl) {}
3199 
3200   void do_code_blob(CodeBlob* cb) {
3201     nmethod* nm = cb->as_nmethod_or_null();
3202     if (nm != NULL) {
3203       _oop_cl->set_nmethod(nm);
3204       nm->oops_do(_oop_cl);
3205     }
3206   }
3207 };
3208 
3209 class YoungRefCounterClosure : public OopClosure {
3210   G1CollectedHeap* _g1h;
3211   int              _count;
3212  public:
3213   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3214   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3215   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3216 
3217   int count() { return _count; }
3218   void reset_count() { _count = 0; };
3219 };
3220 
3221 class VerifyKlassClosure: public KlassClosure {
3222   YoungRefCounterClosure _young_ref_counter_closure;
3223   OopClosure *_oop_closure;
3224  public:
3225   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3226   void do_klass(Klass* k) {
3227     k->oops_do(_oop_closure);
3228 
3229     _young_ref_counter_closure.reset_count();
3230     k->oops_do(&_young_ref_counter_closure);
3231     if (_young_ref_counter_closure.count() > 0) {
3232       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3233     }
3234   }
3235 };
3236 
3237 class VerifyLivenessOopClosure: public OopClosure {
3238   G1CollectedHeap* _g1h;
3239   VerifyOption _vo;
3240 public:
3241   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3242     _g1h(g1h), _vo(vo)
3243   { }
3244   void do_oop(narrowOop *p) { do_oop_work(p); }
3245   void do_oop(      oop *p) { do_oop_work(p); }
3246 
3247   template <class T> void do_oop_work(T *p) {
3248     oop obj = oopDesc::load_decode_heap_oop(p);
3249     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3250               "Dead object referenced by a not dead object");
3251   }
3252 };
3253 
3254 class VerifyObjsInRegionClosure: public ObjectClosure {
3255 private:
3256   G1CollectedHeap* _g1h;
3257   size_t _live_bytes;
3258   HeapRegion *_hr;
3259   VerifyOption _vo;
3260 public:
3261   // _vo == UsePrevMarking -> use "prev" marking information,
3262   // _vo == UseNextMarking -> use "next" marking information,
3263   // _vo == UseMarkWord    -> use mark word from object header.
3264   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3265     : _live_bytes(0), _hr(hr), _vo(vo) {
3266     _g1h = G1CollectedHeap::heap();
3267   }
3268   void do_object(oop o) {
3269     VerifyLivenessOopClosure isLive(_g1h, _vo);
3270     assert(o != NULL, "Huh?");
3271     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3272       // If the object is alive according to the mark word,
3273       // then verify that the marking information agrees.
3274       // Note we can't verify the contra-positive of the
3275       // above: if the object is dead (according to the mark
3276       // word), it may not be marked, or may have been marked
3277       // but has since became dead, or may have been allocated
3278       // since the last marking.
3279       if (_vo == VerifyOption_G1UseMarkWord) {
3280         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3281       }
3282 
3283       o->oop_iterate_no_header(&isLive);
3284       if (!_hr->obj_allocated_since_prev_marking(o)) {
3285         size_t obj_size = o->size();    // Make sure we don't overflow
3286         _live_bytes += (obj_size * HeapWordSize);
3287       }
3288     }
3289   }
3290   size_t live_bytes() { return _live_bytes; }
3291 };
3292 
3293 class PrintObjsInRegionClosure : public ObjectClosure {
3294   HeapRegion *_hr;
3295   G1CollectedHeap *_g1;
3296 public:
3297   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3298     _g1 = G1CollectedHeap::heap();
3299   };
3300 
3301   void do_object(oop o) {
3302     if (o != NULL) {
3303       HeapWord *start = (HeapWord *) o;
3304       size_t word_sz = o->size();
3305       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3306                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3307                           (void*) o, word_sz,
3308                           _g1->isMarkedPrev(o),
3309                           _g1->isMarkedNext(o),
3310                           _hr->obj_allocated_since_prev_marking(o));
3311       HeapWord *end = start + word_sz;
3312       HeapWord *cur;
3313       int *val;
3314       for (cur = start; cur < end; cur++) {
3315         val = (int *) cur;
3316         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3317       }
3318     }
3319   }
3320 };
3321 
3322 class VerifyRegionClosure: public HeapRegionClosure {
3323 private:
3324   bool             _par;
3325   VerifyOption     _vo;
3326   bool             _failures;
3327 public:
3328   // _vo == UsePrevMarking -> use "prev" marking information,
3329   // _vo == UseNextMarking -> use "next" marking information,
3330   // _vo == UseMarkWord    -> use mark word from object header.
3331   VerifyRegionClosure(bool par, VerifyOption vo)
3332     : _par(par),
3333       _vo(vo),
3334       _failures(false) {}
3335 
3336   bool failures() {
3337     return _failures;
3338   }
3339 
3340   bool doHeapRegion(HeapRegion* r) {
3341     if (!r->continuesHumongous()) {
3342       bool failures = false;
3343       r->verify(_vo, &failures);
3344       if (failures) {
3345         _failures = true;
3346       } else {
3347         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3348         r->object_iterate(&not_dead_yet_cl);
3349         if (_vo != VerifyOption_G1UseNextMarking) {
3350           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3351             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3352                                    "max_live_bytes "SIZE_FORMAT" "
3353                                    "< calculated "SIZE_FORMAT,
3354                                    r->bottom(), r->end(),
3355                                    r->max_live_bytes(),
3356                                  not_dead_yet_cl.live_bytes());
3357             _failures = true;
3358           }
3359         } else {
3360           // When vo == UseNextMarking we cannot currently do a sanity
3361           // check on the live bytes as the calculation has not been
3362           // finalized yet.
3363         }
3364       }
3365     }
3366     return false; // stop the region iteration if we hit a failure
3367   }
3368 };
3369 
3370 // This is the task used for parallel verification of the heap regions
3371 
3372 class G1ParVerifyTask: public AbstractGangTask {
3373 private:
3374   G1CollectedHeap* _g1h;
3375   VerifyOption     _vo;
3376   bool             _failures;
3377 
3378 public:
3379   // _vo == UsePrevMarking -> use "prev" marking information,
3380   // _vo == UseNextMarking -> use "next" marking information,
3381   // _vo == UseMarkWord    -> use mark word from object header.
3382   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3383     AbstractGangTask("Parallel verify task"),
3384     _g1h(g1h),
3385     _vo(vo),
3386     _failures(false) { }
3387 
3388   bool failures() {
3389     return _failures;
3390   }
3391 
3392   void work(uint worker_id) {
3393     HandleMark hm;
3394     VerifyRegionClosure blk(true, _vo);
3395     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3396                                           _g1h->workers()->active_workers(),
3397                                           HeapRegion::ParVerifyClaimValue);
3398     if (blk.failures()) {
3399       _failures = true;
3400     }
3401   }
3402 };
3403 
3404 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3405   if (SafepointSynchronize::is_at_safepoint()) {
3406     assert(Thread::current()->is_VM_thread(),
3407            "Expected to be executed serially by the VM thread at this point");
3408 
3409     if (!silent) { gclog_or_tty->print("Roots "); }
3410     VerifyRootsClosure rootsCl(vo);
3411     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3412     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3413     VerifyKlassClosure klassCl(this, &rootsCl);
3414 
3415     // We apply the relevant closures to all the oops in the
3416     // system dictionary, the string table and the code cache.
3417     const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3418 
3419     // Need cleared claim bits for the strong roots processing
3420     ClassLoaderDataGraph::clear_claimed_marks();
3421 
3422     process_strong_roots(true,      // activate StrongRootsScope
3423                          false,     // we set "is scavenging" to false,
3424                                     // so we don't reset the dirty cards.
3425                          ScanningOption(so),  // roots scanning options
3426                          &rootsCl,
3427                          &blobsCl,
3428                          &klassCl
3429                          );
3430 
3431     bool failures = rootsCl.failures() || codeRootsCl.failures();
3432 
3433     if (vo != VerifyOption_G1UseMarkWord) {
3434       // If we're verifying during a full GC then the region sets
3435       // will have been torn down at the start of the GC. Therefore
3436       // verifying the region sets will fail. So we only verify
3437       // the region sets when not in a full GC.
3438       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3439       verify_region_sets();
3440     }
3441 
3442     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3443     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3444       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3445              "sanity check");
3446 
3447       G1ParVerifyTask task(this, vo);
3448       assert(UseDynamicNumberOfGCThreads ||
3449         workers()->active_workers() == workers()->total_workers(),
3450         "If not dynamic should be using all the workers");
3451       int n_workers = workers()->active_workers();
3452       set_par_threads(n_workers);
3453       workers()->run_task(&task);
3454       set_par_threads(0);
3455       if (task.failures()) {
3456         failures = true;
3457       }
3458 
3459       // Checks that the expected amount of parallel work was done.
3460       // The implication is that n_workers is > 0.
3461       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3462              "sanity check");
3463 
3464       reset_heap_region_claim_values();
3465 
3466       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3467              "sanity check");
3468     } else {
3469       VerifyRegionClosure blk(false, vo);
3470       heap_region_iterate(&blk);
3471       if (blk.failures()) {
3472         failures = true;
3473       }
3474     }
3475     if (!silent) gclog_or_tty->print("RemSet ");
3476     rem_set()->verify();
3477 
3478     if (failures) {
3479       gclog_or_tty->print_cr("Heap:");
3480       // It helps to have the per-region information in the output to
3481       // help us track down what went wrong. This is why we call
3482       // print_extended_on() instead of print_on().
3483       print_extended_on(gclog_or_tty);
3484       gclog_or_tty->print_cr("");
3485 #ifndef PRODUCT
3486       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3487         concurrent_mark()->print_reachable("at-verification-failure",
3488                                            vo, false /* all */);
3489       }
3490 #endif
3491       gclog_or_tty->flush();
3492     }
3493     guarantee(!failures, "there should not have been any failures");
3494   } else {
3495     if (!silent)
3496       gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3497   }
3498 }
3499 
3500 void G1CollectedHeap::verify(bool silent) {
3501   verify(silent, VerifyOption_G1UsePrevMarking);
3502 }
3503 
3504 double G1CollectedHeap::verify(bool guard, const char* msg) {
3505   double verify_time_ms = 0.0;
3506 
3507   if (guard && total_collections() >= VerifyGCStartAt) {
3508     double verify_start = os::elapsedTime();
3509     HandleMark hm;  // Discard invalid handles created during verification
3510     prepare_for_verify();
3511     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3512     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3513   }
3514 
3515   return verify_time_ms;
3516 }
3517 
3518 void G1CollectedHeap::verify_before_gc() {
3519   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3520   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3521 }
3522 
3523 void G1CollectedHeap::verify_after_gc() {
3524   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3525   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3526 }
3527 
3528 class PrintRegionClosure: public HeapRegionClosure {
3529   outputStream* _st;
3530 public:
3531   PrintRegionClosure(outputStream* st) : _st(st) {}
3532   bool doHeapRegion(HeapRegion* r) {
3533     r->print_on(_st);
3534     return false;
3535   }
3536 };
3537 
3538 void G1CollectedHeap::print_on(outputStream* st) const {
3539   st->print(" %-20s", "garbage-first heap");
3540   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3541             capacity()/K, used_unlocked()/K);
3542   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3543             _g1_storage.low_boundary(),
3544             _g1_storage.high(),
3545             _g1_storage.high_boundary());
3546   st->cr();
3547   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3548   uint young_regions = _young_list->length();
3549   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3550             (size_t) young_regions * HeapRegion::GrainBytes / K);
3551   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3552   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3553             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3554   st->cr();
3555   MetaspaceAux::print_on(st);
3556 }
3557 
3558 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3559   print_on(st);
3560 
3561   // Print the per-region information.
3562   st->cr();
3563   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3564                "HS=humongous(starts), HC=humongous(continues), "
3565                "CS=collection set, F=free, TS=gc time stamp, "
3566                "PTAMS=previous top-at-mark-start, "
3567                "NTAMS=next top-at-mark-start)");
3568   PrintRegionClosure blk(st);
3569   heap_region_iterate(&blk);
3570 }
3571 
3572 void G1CollectedHeap::print_on_error(outputStream* st) const {
3573   this->CollectedHeap::print_on_error(st);
3574 
3575   if (_cm != NULL) {
3576     st->cr();
3577     _cm->print_on_error(st);
3578   }
3579 }
3580 
3581 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3582   if (G1CollectedHeap::use_parallel_gc_threads()) {
3583     workers()->print_worker_threads_on(st);
3584   }
3585   _cmThread->print_on(st);
3586   st->cr();
3587   _cm->print_worker_threads_on(st);
3588   _cg1r->print_worker_threads_on(st);
3589 }
3590 
3591 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3592   if (G1CollectedHeap::use_parallel_gc_threads()) {
3593     workers()->threads_do(tc);
3594   }
3595   tc->do_thread(_cmThread);
3596   _cg1r->threads_do(tc);
3597 }
3598 
3599 void G1CollectedHeap::print_tracing_info() const {
3600   // We'll overload this to mean "trace GC pause statistics."
3601   if (TraceGen0Time || TraceGen1Time) {
3602     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3603     // to that.
3604     g1_policy()->print_tracing_info();
3605   }
3606   if (G1SummarizeRSetStats) {
3607     g1_rem_set()->print_summary_info();
3608   }
3609   if (G1SummarizeConcMark) {
3610     concurrent_mark()->print_summary_info();
3611   }
3612   g1_policy()->print_yg_surv_rate_info();
3613   SpecializationStats::print();
3614 }
3615 
3616 #ifndef PRODUCT
3617 // Helpful for debugging RSet issues.
3618 
3619 class PrintRSetsClosure : public HeapRegionClosure {
3620 private:
3621   const char* _msg;
3622   size_t _occupied_sum;
3623 
3624 public:
3625   bool doHeapRegion(HeapRegion* r) {
3626     HeapRegionRemSet* hrrs = r->rem_set();
3627     size_t occupied = hrrs->occupied();
3628     _occupied_sum += occupied;
3629 
3630     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3631                            HR_FORMAT_PARAMS(r));
3632     if (occupied == 0) {
3633       gclog_or_tty->print_cr("  RSet is empty");
3634     } else {
3635       hrrs->print();
3636     }
3637     gclog_or_tty->print_cr("----------");
3638     return false;
3639   }
3640 
3641   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3642     gclog_or_tty->cr();
3643     gclog_or_tty->print_cr("========================================");
3644     gclog_or_tty->print_cr(msg);
3645     gclog_or_tty->cr();
3646   }
3647 
3648   ~PrintRSetsClosure() {
3649     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3650     gclog_or_tty->print_cr("========================================");
3651     gclog_or_tty->cr();
3652   }
3653 };
3654 
3655 void G1CollectedHeap::print_cset_rsets() {
3656   PrintRSetsClosure cl("Printing CSet RSets");
3657   collection_set_iterate(&cl);
3658 }
3659 
3660 void G1CollectedHeap::print_all_rsets() {
3661   PrintRSetsClosure cl("Printing All RSets");;
3662   heap_region_iterate(&cl);
3663 }
3664 #endif // PRODUCT
3665 
3666 G1CollectedHeap* G1CollectedHeap::heap() {
3667   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3668          "not a garbage-first heap");
3669   return _g1h;
3670 }
3671 
3672 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3673   // always_do_update_barrier = false;
3674   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3675   // Fill TLAB's and such
3676   ensure_parsability(true);
3677 
3678   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3679       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3680     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3681   }
3682 }
3683 
3684 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3685 
3686   if (G1SummarizeRSetStats &&
3687       (G1SummarizeRSetStatsPeriod > 0) &&
3688       // we are at the end of the GC. Total collections has already been increased.
3689       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3690     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3691   }
3692 
3693   // FIXME: what is this about?
3694   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3695   // is set.
3696   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3697                         "derived pointer present"));
3698   // always_do_update_barrier = true;
3699 
3700   // We have just completed a GC. Update the soft reference
3701   // policy with the new heap occupancy
3702   Universe::update_heap_info_at_gc();
3703 }
3704 
3705 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3706                                                unsigned int gc_count_before,
3707                                                bool* succeeded,
3708                                                GCCause::Cause gc_cause) {
3709   assert_heap_not_locked_and_not_at_safepoint();
3710   g1_policy()->record_stop_world_start();
3711   VM_G1IncCollectionPause op(gc_count_before,
3712                              word_size,
3713                              false, /* should_initiate_conc_mark */
3714                              g1_policy()->max_pause_time_ms(),
3715                              gc_cause);
3716   VMThread::execute(&op);
3717 
3718   HeapWord* result = op.result();
3719   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3720   assert(result == NULL || ret_succeeded,
3721          "the result should be NULL if the VM did not succeed");
3722   *succeeded = ret_succeeded;
3723 
3724   assert_heap_not_locked();
3725   return result;
3726 }
3727 
3728 void
3729 G1CollectedHeap::doConcurrentMark() {
3730   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3731   if (!_cmThread->in_progress()) {
3732     _cmThread->set_started();
3733     CGC_lock->notify();
3734   }
3735 }
3736 
3737 size_t G1CollectedHeap::pending_card_num() {
3738   size_t extra_cards = 0;
3739   JavaThread *curr = Threads::first();
3740   while (curr != NULL) {
3741     DirtyCardQueue& dcq = curr->dirty_card_queue();
3742     extra_cards += dcq.size();
3743     curr = curr->next();
3744   }
3745   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3746   size_t buffer_size = dcqs.buffer_size();
3747   size_t buffer_num = dcqs.completed_buffers_num();
3748 
3749   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3750   // in bytes - not the number of 'entries'. We need to convert
3751   // into a number of cards.
3752   return (buffer_size * buffer_num + extra_cards) / oopSize;
3753 }
3754 
3755 size_t G1CollectedHeap::cards_scanned() {
3756   return g1_rem_set()->cardsScanned();
3757 }
3758 
3759 void
3760 G1CollectedHeap::setup_surviving_young_words() {
3761   assert(_surviving_young_words == NULL, "pre-condition");
3762   uint array_length = g1_policy()->young_cset_region_length();
3763   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3764   if (_surviving_young_words == NULL) {
3765     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3766                           "Not enough space for young surv words summary.");
3767   }
3768   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3769 #ifdef ASSERT
3770   for (uint i = 0;  i < array_length; ++i) {
3771     assert( _surviving_young_words[i] == 0, "memset above" );
3772   }
3773 #endif // !ASSERT
3774 }
3775 
3776 void
3777 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3778   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3779   uint array_length = g1_policy()->young_cset_region_length();
3780   for (uint i = 0; i < array_length; ++i) {
3781     _surviving_young_words[i] += surv_young_words[i];
3782   }
3783 }
3784 
3785 void
3786 G1CollectedHeap::cleanup_surviving_young_words() {
3787   guarantee( _surviving_young_words != NULL, "pre-condition" );
3788   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3789   _surviving_young_words = NULL;
3790 }
3791 
3792 #ifdef ASSERT
3793 class VerifyCSetClosure: public HeapRegionClosure {
3794 public:
3795   bool doHeapRegion(HeapRegion* hr) {
3796     // Here we check that the CSet region's RSet is ready for parallel
3797     // iteration. The fields that we'll verify are only manipulated
3798     // when the region is part of a CSet and is collected. Afterwards,
3799     // we reset these fields when we clear the region's RSet (when the
3800     // region is freed) so they are ready when the region is
3801     // re-allocated. The only exception to this is if there's an
3802     // evacuation failure and instead of freeing the region we leave
3803     // it in the heap. In that case, we reset these fields during
3804     // evacuation failure handling.
3805     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3806 
3807     // Here's a good place to add any other checks we'd like to
3808     // perform on CSet regions.
3809     return false;
3810   }
3811 };
3812 #endif // ASSERT
3813 
3814 #if TASKQUEUE_STATS
3815 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3816   st->print_raw_cr("GC Task Stats");
3817   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3818   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3819 }
3820 
3821 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3822   print_taskqueue_stats_hdr(st);
3823 
3824   TaskQueueStats totals;
3825   const int n = workers() != NULL ? workers()->total_workers() : 1;
3826   for (int i = 0; i < n; ++i) {
3827     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3828     totals += task_queue(i)->stats;
3829   }
3830   st->print_raw("tot "); totals.print(st); st->cr();
3831 
3832   DEBUG_ONLY(totals.verify());
3833 }
3834 
3835 void G1CollectedHeap::reset_taskqueue_stats() {
3836   const int n = workers() != NULL ? workers()->total_workers() : 1;
3837   for (int i = 0; i < n; ++i) {
3838     task_queue(i)->stats.reset();
3839   }
3840 }
3841 #endif // TASKQUEUE_STATS
3842 
3843 void G1CollectedHeap::log_gc_header() {
3844   if (!G1Log::fine()) {
3845     return;
3846   }
3847 
3848   gclog_or_tty->date_stamp(PrintGCDateStamps);
3849   gclog_or_tty->stamp(PrintGCTimeStamps);
3850 
3851   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3852     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3853     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3854 
3855   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3856 }
3857 
3858 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3859   if (!G1Log::fine()) {
3860     return;
3861   }
3862 
3863   if (G1Log::finer()) {
3864     if (evacuation_failed()) {
3865       gclog_or_tty->print(" (to-space exhausted)");
3866     }
3867     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3868     g1_policy()->phase_times()->note_gc_end();
3869     g1_policy()->phase_times()->print(pause_time_sec);
3870     g1_policy()->print_detailed_heap_transition();
3871   } else {
3872     if (evacuation_failed()) {
3873       gclog_or_tty->print("--");
3874     }
3875     g1_policy()->print_heap_transition();
3876     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3877   }
3878   gclog_or_tty->flush();
3879 }
3880 
3881 bool
3882 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3883   assert_at_safepoint(true /* should_be_vm_thread */);
3884   guarantee(!is_gc_active(), "collection is not reentrant");
3885 
3886   if (GC_locker::check_active_before_gc()) {
3887     return false;
3888   }
3889 
3890   _gc_timer_stw->register_gc_start(os::elapsed_counter());
3891 
3892   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3893 
3894   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3895   ResourceMark rm;
3896 
3897   print_heap_before_gc();
3898   trace_heap_before_gc(_gc_tracer_stw);
3899 
3900   HRSPhaseSetter x(HRSPhaseEvacuation);
3901   verify_region_sets_optional();
3902   verify_dirty_young_regions();
3903 
3904   // This call will decide whether this pause is an initial-mark
3905   // pause. If it is, during_initial_mark_pause() will return true
3906   // for the duration of this pause.
3907   g1_policy()->decide_on_conc_mark_initiation();
3908 
3909   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3910   assert(!g1_policy()->during_initial_mark_pause() ||
3911           g1_policy()->gcs_are_young(), "sanity");
3912 
3913   // We also do not allow mixed GCs during marking.
3914   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3915 
3916   // Record whether this pause is an initial mark. When the current
3917   // thread has completed its logging output and it's safe to signal
3918   // the CM thread, the flag's value in the policy has been reset.
3919   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3920 
3921   // Inner scope for scope based logging, timers, and stats collection
3922   {
3923     EvacuationInfo evacuation_info;
3924 
3925     if (g1_policy()->during_initial_mark_pause()) {
3926       // We are about to start a marking cycle, so we increment the
3927       // full collection counter.
3928       increment_old_marking_cycles_started();
3929       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3930     }
3931 
3932     _gc_tracer_stw->report_yc_type(yc_type());
3933 
3934     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3935 
3936     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3937                                 workers()->active_workers() : 1);
3938     double pause_start_sec = os::elapsedTime();
3939     g1_policy()->phase_times()->note_gc_start(active_workers);
3940     log_gc_header();
3941 
3942     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3943     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3944 
3945     // If the secondary_free_list is not empty, append it to the
3946     // free_list. No need to wait for the cleanup operation to finish;
3947     // the region allocation code will check the secondary_free_list
3948     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3949     // set, skip this step so that the region allocation code has to
3950     // get entries from the secondary_free_list.
3951     if (!G1StressConcRegionFreeing) {
3952       append_secondary_free_list_if_not_empty_with_lock();
3953     }
3954 
3955     assert(check_young_list_well_formed(), "young list should be well formed");
3956     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3957            "sanity check");
3958 
3959     // Don't dynamically change the number of GC threads this early.  A value of
3960     // 0 is used to indicate serial work.  When parallel work is done,
3961     // it will be set.
3962 
3963     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3964       IsGCActiveMark x;
3965 
3966       gc_prologue(false);
3967       increment_total_collections(false /* full gc */);
3968       increment_gc_time_stamp();
3969 
3970       verify_before_gc();
3971 
3972       COMPILER2_PRESENT(DerivedPointerTable::clear());
3973 
3974       // Please see comment in g1CollectedHeap.hpp and
3975       // G1CollectedHeap::ref_processing_init() to see how
3976       // reference processing currently works in G1.
3977 
3978       // Enable discovery in the STW reference processor
3979       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3980                                             true /*verify_no_refs*/);
3981 
3982       {
3983         // We want to temporarily turn off discovery by the
3984         // CM ref processor, if necessary, and turn it back on
3985         // on again later if we do. Using a scoped
3986         // NoRefDiscovery object will do this.
3987         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3988 
3989         // Forget the current alloc region (we might even choose it to be part
3990         // of the collection set!).
3991         release_mutator_alloc_region();
3992 
3993         // We should call this after we retire the mutator alloc
3994         // region(s) so that all the ALLOC / RETIRE events are generated
3995         // before the start GC event.
3996         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3997 
3998         // This timing is only used by the ergonomics to handle our pause target.
3999         // It is unclear why this should not include the full pause. We will
4000         // investigate this in CR 7178365.
4001         //
4002         // Preserving the old comment here if that helps the investigation:
4003         //
4004         // The elapsed time induced by the start time below deliberately elides
4005         // the possible verification above.
4006         double sample_start_time_sec = os::elapsedTime();
4007 
4008 #if YOUNG_LIST_VERBOSE
4009         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4010         _young_list->print();
4011         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4012 #endif // YOUNG_LIST_VERBOSE
4013 
4014         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4015 
4016         double scan_wait_start = os::elapsedTime();
4017         // We have to wait until the CM threads finish scanning the
4018         // root regions as it's the only way to ensure that all the
4019         // objects on them have been correctly scanned before we start
4020         // moving them during the GC.
4021         bool waited = _cm->root_regions()->wait_until_scan_finished();
4022         double wait_time_ms = 0.0;
4023         if (waited) {
4024           double scan_wait_end = os::elapsedTime();
4025           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4026         }
4027         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4028 
4029 #if YOUNG_LIST_VERBOSE
4030         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4031         _young_list->print();
4032 #endif // YOUNG_LIST_VERBOSE
4033 
4034         if (g1_policy()->during_initial_mark_pause()) {
4035           concurrent_mark()->checkpointRootsInitialPre();
4036         }
4037 
4038 #if YOUNG_LIST_VERBOSE
4039         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4040         _young_list->print();
4041         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4042 #endif // YOUNG_LIST_VERBOSE
4043 
4044         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4045 
4046         _cm->note_start_of_gc();
4047         // We should not verify the per-thread SATB buffers given that
4048         // we have not filtered them yet (we'll do so during the
4049         // GC). We also call this after finalize_cset() to
4050         // ensure that the CSet has been finalized.
4051         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4052                                  true  /* verify_enqueued_buffers */,
4053                                  false /* verify_thread_buffers */,
4054                                  true  /* verify_fingers */);
4055 
4056         if (_hr_printer.is_active()) {
4057           HeapRegion* hr = g1_policy()->collection_set();
4058           while (hr != NULL) {
4059             G1HRPrinter::RegionType type;
4060             if (!hr->is_young()) {
4061               type = G1HRPrinter::Old;
4062             } else if (hr->is_survivor()) {
4063               type = G1HRPrinter::Survivor;
4064             } else {
4065               type = G1HRPrinter::Eden;
4066             }
4067             _hr_printer.cset(hr);
4068             hr = hr->next_in_collection_set();
4069           }
4070         }
4071 
4072 #ifdef ASSERT
4073         VerifyCSetClosure cl;
4074         collection_set_iterate(&cl);
4075 #endif // ASSERT
4076 
4077         setup_surviving_young_words();
4078 
4079         // Initialize the GC alloc regions.
4080         init_gc_alloc_regions(evacuation_info);
4081 
4082         // Actually do the work...
4083         evacuate_collection_set(evacuation_info);
4084 
4085         // We do this to mainly verify the per-thread SATB buffers
4086         // (which have been filtered by now) since we didn't verify
4087         // them earlier. No point in re-checking the stacks / enqueued
4088         // buffers given that the CSet has not changed since last time
4089         // we checked.
4090         _cm->verify_no_cset_oops(false /* verify_stacks */,
4091                                  false /* verify_enqueued_buffers */,
4092                                  true  /* verify_thread_buffers */,
4093                                  true  /* verify_fingers */);
4094 
4095         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4096         g1_policy()->clear_collection_set();
4097 
4098         cleanup_surviving_young_words();
4099 
4100         // Start a new incremental collection set for the next pause.
4101         g1_policy()->start_incremental_cset_building();
4102 
4103         // Clear the _cset_fast_test bitmap in anticipation of adding
4104         // regions to the incremental collection set for the next
4105         // evacuation pause.
4106         clear_cset_fast_test();
4107 
4108         _young_list->reset_sampled_info();
4109 
4110         // Don't check the whole heap at this point as the
4111         // GC alloc regions from this pause have been tagged
4112         // as survivors and moved on to the survivor list.
4113         // Survivor regions will fail the !is_young() check.
4114         assert(check_young_list_empty(false /* check_heap */),
4115           "young list should be empty");
4116 
4117 #if YOUNG_LIST_VERBOSE
4118         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4119         _young_list->print();
4120 #endif // YOUNG_LIST_VERBOSE
4121 
4122         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4123                                              _young_list->first_survivor_region(),
4124                                              _young_list->last_survivor_region());
4125 
4126         _young_list->reset_auxilary_lists();
4127 
4128         if (evacuation_failed()) {
4129           _summary_bytes_used = recalculate_used();
4130           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4131           for (uint i = 0; i < n_queues; i++) {
4132             if (_evacuation_failed_info_array[i].has_failed()) {
4133               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4134             }
4135           }
4136         } else {
4137           // The "used" of the the collection set have already been subtracted
4138           // when they were freed.  Add in the bytes evacuated.
4139           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4140         }
4141 
4142         if (g1_policy()->during_initial_mark_pause()) {
4143           // We have to do this before we notify the CM threads that
4144           // they can start working to make sure that all the
4145           // appropriate initialization is done on the CM object.
4146           concurrent_mark()->checkpointRootsInitialPost();
4147           set_marking_started();
4148           // Note that we don't actually trigger the CM thread at
4149           // this point. We do that later when we're sure that
4150           // the current thread has completed its logging output.
4151         }
4152 
4153         allocate_dummy_regions();
4154 
4155 #if YOUNG_LIST_VERBOSE
4156         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4157         _young_list->print();
4158         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4159 #endif // YOUNG_LIST_VERBOSE
4160 
4161         init_mutator_alloc_region();
4162 
4163         {
4164           size_t expand_bytes = g1_policy()->expansion_amount();
4165           if (expand_bytes > 0) {
4166             size_t bytes_before = capacity();
4167             // No need for an ergo verbose message here,
4168             // expansion_amount() does this when it returns a value > 0.
4169             if (!expand(expand_bytes)) {
4170               // We failed to expand the heap so let's verify that
4171               // committed/uncommitted amount match the backing store
4172               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4173               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4174             }
4175           }
4176         }
4177 
4178         // We redo the verification but now wrt to the new CSet which
4179         // has just got initialized after the previous CSet was freed.
4180         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4181                                  true  /* verify_enqueued_buffers */,
4182                                  true  /* verify_thread_buffers */,
4183                                  true  /* verify_fingers */);
4184         _cm->note_end_of_gc();
4185 
4186         // This timing is only used by the ergonomics to handle our pause target.
4187         // It is unclear why this should not include the full pause. We will
4188         // investigate this in CR 7178365.
4189         double sample_end_time_sec = os::elapsedTime();
4190         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4191         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4192 
4193         MemoryService::track_memory_usage();
4194 
4195         // In prepare_for_verify() below we'll need to scan the deferred
4196         // update buffers to bring the RSets up-to-date if
4197         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4198         // the update buffers we'll probably need to scan cards on the
4199         // regions we just allocated to (i.e., the GC alloc
4200         // regions). However, during the last GC we called
4201         // set_saved_mark() on all the GC alloc regions, so card
4202         // scanning might skip the [saved_mark_word()...top()] area of
4203         // those regions (i.e., the area we allocated objects into
4204         // during the last GC). But it shouldn't. Given that
4205         // saved_mark_word() is conditional on whether the GC time stamp
4206         // on the region is current or not, by incrementing the GC time
4207         // stamp here we invalidate all the GC time stamps on all the
4208         // regions and saved_mark_word() will simply return top() for
4209         // all the regions. This is a nicer way of ensuring this rather
4210         // than iterating over the regions and fixing them. In fact, the
4211         // GC time stamp increment here also ensures that
4212         // saved_mark_word() will return top() between pauses, i.e.,
4213         // during concurrent refinement. So we don't need the
4214         // is_gc_active() check to decided which top to use when
4215         // scanning cards (see CR 7039627).
4216         increment_gc_time_stamp();
4217 
4218         verify_after_gc();
4219 
4220         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4221         ref_processor_stw()->verify_no_references_recorded();
4222 
4223         // CM reference discovery will be re-enabled if necessary.
4224       }
4225 
4226       // We should do this after we potentially expand the heap so
4227       // that all the COMMIT events are generated before the end GC
4228       // event, and after we retire the GC alloc regions so that all
4229       // RETIRE events are generated before the end GC event.
4230       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4231 
4232       if (mark_in_progress()) {
4233         concurrent_mark()->update_g1_committed();
4234       }
4235 
4236 #ifdef TRACESPINNING
4237       ParallelTaskTerminator::print_termination_counts();
4238 #endif
4239 
4240       gc_epilogue(false);
4241     }
4242 
4243     // Print the remainder of the GC log output.
4244     log_gc_footer(os::elapsedTime() - pause_start_sec);
4245 
4246     // It is not yet to safe to tell the concurrent mark to
4247     // start as we have some optional output below. We don't want the
4248     // output from the concurrent mark thread interfering with this
4249     // logging output either.
4250 
4251     _hrs.verify_optional();
4252     verify_region_sets_optional();
4253 
4254     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4255     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4256 
4257     print_heap_after_gc();
4258     trace_heap_after_gc(_gc_tracer_stw);
4259 
4260     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4261     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4262     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4263     // before any GC notifications are raised.
4264     g1mm()->update_sizes();
4265 
4266     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4267     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4268     _gc_timer_stw->register_gc_end(os::elapsed_counter());
4269     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4270   }
4271   // It should now be safe to tell the concurrent mark thread to start
4272   // without its logging output interfering with the logging output
4273   // that came from the pause.
4274 
4275   if (should_start_conc_mark) {
4276     // CAUTION: after the doConcurrentMark() call below,
4277     // the concurrent marking thread(s) could be running
4278     // concurrently with us. Make sure that anything after
4279     // this point does not assume that we are the only GC thread
4280     // running. Note: of course, the actual marking work will
4281     // not start until the safepoint itself is released in
4282     // ConcurrentGCThread::safepoint_desynchronize().
4283     doConcurrentMark();
4284   }
4285 
4286   return true;
4287 }
4288 
4289 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4290 {
4291   size_t gclab_word_size;
4292   switch (purpose) {
4293     case GCAllocForSurvived:
4294       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4295       break;
4296     case GCAllocForTenured:
4297       gclab_word_size = _old_plab_stats.desired_plab_sz();
4298       break;
4299     default:
4300       assert(false, "unknown GCAllocPurpose");
4301       gclab_word_size = _old_plab_stats.desired_plab_sz();
4302       break;
4303   }
4304 
4305   // Prevent humongous PLAB sizes for two reasons:
4306   // * PLABs are allocated using a similar paths as oops, but should
4307   //   never be in a humongous region
4308   // * Allowing humongous PLABs needlessly churns the region free lists
4309   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4310 }
4311 
4312 void G1CollectedHeap::init_mutator_alloc_region() {
4313   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4314   _mutator_alloc_region.init();
4315 }
4316 
4317 void G1CollectedHeap::release_mutator_alloc_region() {
4318   _mutator_alloc_region.release();
4319   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4320 }
4321 
4322 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4323   assert_at_safepoint(true /* should_be_vm_thread */);
4324 
4325   _survivor_gc_alloc_region.init();
4326   _old_gc_alloc_region.init();
4327   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4328   _retained_old_gc_alloc_region = NULL;
4329 
4330   // We will discard the current GC alloc region if:
4331   // a) it's in the collection set (it can happen!),
4332   // b) it's already full (no point in using it),
4333   // c) it's empty (this means that it was emptied during
4334   // a cleanup and it should be on the free list now), or
4335   // d) it's humongous (this means that it was emptied
4336   // during a cleanup and was added to the free list, but
4337   // has been subsequently used to allocate a humongous
4338   // object that may be less than the region size).
4339   if (retained_region != NULL &&
4340       !retained_region->in_collection_set() &&
4341       !(retained_region->top() == retained_region->end()) &&
4342       !retained_region->is_empty() &&
4343       !retained_region->isHumongous()) {
4344     retained_region->set_saved_mark();
4345     // The retained region was added to the old region set when it was
4346     // retired. We have to remove it now, since we don't allow regions
4347     // we allocate to in the region sets. We'll re-add it later, when
4348     // it's retired again.
4349     _old_set.remove(retained_region);
4350     bool during_im = g1_policy()->during_initial_mark_pause();
4351     retained_region->note_start_of_copying(during_im);
4352     _old_gc_alloc_region.set(retained_region);
4353     _hr_printer.reuse(retained_region);
4354     evacuation_info.set_alloc_regions_used_before(retained_region->used());
4355   }
4356 }
4357 
4358 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4359   evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4360                                          _old_gc_alloc_region.count());
4361   _survivor_gc_alloc_region.release();
4362   // If we have an old GC alloc region to release, we'll save it in
4363   // _retained_old_gc_alloc_region. If we don't
4364   // _retained_old_gc_alloc_region will become NULL. This is what we
4365   // want either way so no reason to check explicitly for either
4366   // condition.
4367   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4368 
4369   if (ResizePLAB) {
4370     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4371     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4372   }
4373 }
4374 
4375 void G1CollectedHeap::abandon_gc_alloc_regions() {
4376   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4377   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4378   _retained_old_gc_alloc_region = NULL;
4379 }
4380 
4381 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4382   _drain_in_progress = false;
4383   set_evac_failure_closure(cl);
4384   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4385 }
4386 
4387 void G1CollectedHeap::finalize_for_evac_failure() {
4388   assert(_evac_failure_scan_stack != NULL &&
4389          _evac_failure_scan_stack->length() == 0,
4390          "Postcondition");
4391   assert(!_drain_in_progress, "Postcondition");
4392   delete _evac_failure_scan_stack;
4393   _evac_failure_scan_stack = NULL;
4394 }
4395 
4396 void G1CollectedHeap::remove_self_forwarding_pointers() {
4397   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4398 
4399   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4400 
4401   if (G1CollectedHeap::use_parallel_gc_threads()) {
4402     set_par_threads();
4403     workers()->run_task(&rsfp_task);
4404     set_par_threads(0);
4405   } else {
4406     rsfp_task.work(0);
4407   }
4408 
4409   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4410 
4411   // Reset the claim values in the regions in the collection set.
4412   reset_cset_heap_region_claim_values();
4413 
4414   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4415 
4416   // Now restore saved marks, if any.
4417   assert(_objs_with_preserved_marks.size() ==
4418             _preserved_marks_of_objs.size(), "Both or none.");
4419   while (!_objs_with_preserved_marks.is_empty()) {
4420     oop obj = _objs_with_preserved_marks.pop();
4421     markOop m = _preserved_marks_of_objs.pop();
4422     obj->set_mark(m);
4423   }
4424   _objs_with_preserved_marks.clear(true);
4425   _preserved_marks_of_objs.clear(true);
4426 }
4427 
4428 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4429   _evac_failure_scan_stack->push(obj);
4430 }
4431 
4432 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4433   assert(_evac_failure_scan_stack != NULL, "precondition");
4434 
4435   while (_evac_failure_scan_stack->length() > 0) {
4436      oop obj = _evac_failure_scan_stack->pop();
4437      _evac_failure_closure->set_region(heap_region_containing(obj));
4438      obj->oop_iterate_backwards(_evac_failure_closure);
4439   }
4440 }
4441 
4442 oop
4443 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4444                                                oop old) {
4445   assert(obj_in_cs(old),
4446          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4447                  (HeapWord*) old));
4448   markOop m = old->mark();
4449   oop forward_ptr = old->forward_to_atomic(old);
4450   if (forward_ptr == NULL) {
4451     // Forward-to-self succeeded.
4452     assert(_par_scan_state != NULL, "par scan state");
4453     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4454     uint queue_num = _par_scan_state->queue_num();
4455 
4456     _evacuation_failed = true;
4457     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4458     if (_evac_failure_closure != cl) {
4459       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4460       assert(!_drain_in_progress,
4461              "Should only be true while someone holds the lock.");
4462       // Set the global evac-failure closure to the current thread's.
4463       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4464       set_evac_failure_closure(cl);
4465       // Now do the common part.
4466       handle_evacuation_failure_common(old, m);
4467       // Reset to NULL.
4468       set_evac_failure_closure(NULL);
4469     } else {
4470       // The lock is already held, and this is recursive.
4471       assert(_drain_in_progress, "This should only be the recursive case.");
4472       handle_evacuation_failure_common(old, m);
4473     }
4474     return old;
4475   } else {
4476     // Forward-to-self failed. Either someone else managed to allocate
4477     // space for this object (old != forward_ptr) or they beat us in
4478     // self-forwarding it (old == forward_ptr).
4479     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4480            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4481                    "should not be in the CSet",
4482                    (HeapWord*) old, (HeapWord*) forward_ptr));
4483     return forward_ptr;
4484   }
4485 }
4486 
4487 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4488   preserve_mark_if_necessary(old, m);
4489 
4490   HeapRegion* r = heap_region_containing(old);
4491   if (!r->evacuation_failed()) {
4492     r->set_evacuation_failed(true);
4493     _hr_printer.evac_failure(r);
4494   }
4495 
4496   push_on_evac_failure_scan_stack(old);
4497 
4498   if (!_drain_in_progress) {
4499     // prevent recursion in copy_to_survivor_space()
4500     _drain_in_progress = true;
4501     drain_evac_failure_scan_stack();
4502     _drain_in_progress = false;
4503   }
4504 }
4505 
4506 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4507   assert(evacuation_failed(), "Oversaving!");
4508   // We want to call the "for_promotion_failure" version only in the
4509   // case of a promotion failure.
4510   if (m->must_be_preserved_for_promotion_failure(obj)) {
4511     _objs_with_preserved_marks.push(obj);
4512     _preserved_marks_of_objs.push(m);
4513   }
4514 }
4515 
4516 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4517                                                   size_t word_size) {
4518   if (purpose == GCAllocForSurvived) {
4519     HeapWord* result = survivor_attempt_allocation(word_size);
4520     if (result != NULL) {
4521       return result;
4522     } else {
4523       // Let's try to allocate in the old gen in case we can fit the
4524       // object there.
4525       return old_attempt_allocation(word_size);
4526     }
4527   } else {
4528     assert(purpose ==  GCAllocForTenured, "sanity");
4529     HeapWord* result = old_attempt_allocation(word_size);
4530     if (result != NULL) {
4531       return result;
4532     } else {
4533       // Let's try to allocate in the survivors in case we can fit the
4534       // object there.
4535       return survivor_attempt_allocation(word_size);
4536     }
4537   }
4538 
4539   ShouldNotReachHere();
4540   // Trying to keep some compilers happy.
4541   return NULL;
4542 }
4543 
4544 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4545   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4546 
4547 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4548   : _g1h(g1h),
4549     _refs(g1h->task_queue(queue_num)),
4550     _dcq(&g1h->dirty_card_queue_set()),
4551     _ct_bs(g1h->g1_barrier_set()),
4552     _g1_rem(g1h->g1_rem_set()),
4553     _hash_seed(17), _queue_num(queue_num),
4554     _term_attempts(0),
4555     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4556     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4557     _age_table(false),
4558     _strong_roots_time(0), _term_time(0),
4559     _alloc_buffer_waste(0), _undo_waste(0) {
4560   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4561   // we "sacrifice" entry 0 to keep track of surviving bytes for
4562   // non-young regions (where the age is -1)
4563   // We also add a few elements at the beginning and at the end in
4564   // an attempt to eliminate cache contention
4565   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4566   uint array_length = PADDING_ELEM_NUM +
4567                       real_length +
4568                       PADDING_ELEM_NUM;
4569   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4570   if (_surviving_young_words_base == NULL)
4571     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4572                           "Not enough space for young surv histo.");
4573   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4574   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4575 
4576   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4577   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4578 
4579   _start = os::elapsedTime();
4580 }
4581 
4582 void
4583 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4584 {
4585   st->print_raw_cr("GC Termination Stats");
4586   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4587                    " ------waste (KiB)------");
4588   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4589                    "  total   alloc    undo");
4590   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4591                    " ------- ------- -------");
4592 }
4593 
4594 void
4595 G1ParScanThreadState::print_termination_stats(int i,
4596                                               outputStream* const st) const
4597 {
4598   const double elapsed_ms = elapsed_time() * 1000.0;
4599   const double s_roots_ms = strong_roots_time() * 1000.0;
4600   const double term_ms    = term_time() * 1000.0;
4601   st->print_cr("%3d %9.2f %9.2f %6.2f "
4602                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4603                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4604                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4605                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4606                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4607                alloc_buffer_waste() * HeapWordSize / K,
4608                undo_waste() * HeapWordSize / K);
4609 }
4610 
4611 #ifdef ASSERT
4612 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4613   assert(ref != NULL, "invariant");
4614   assert(UseCompressedOops, "sanity");
4615   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4616   oop p = oopDesc::load_decode_heap_oop(ref);
4617   assert(_g1h->is_in_g1_reserved(p),
4618          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4619   return true;
4620 }
4621 
4622 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4623   assert(ref != NULL, "invariant");
4624   if (has_partial_array_mask(ref)) {
4625     // Must be in the collection set--it's already been copied.
4626     oop p = clear_partial_array_mask(ref);
4627     assert(_g1h->obj_in_cs(p),
4628            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4629   } else {
4630     oop p = oopDesc::load_decode_heap_oop(ref);
4631     assert(_g1h->is_in_g1_reserved(p),
4632            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4633   }
4634   return true;
4635 }
4636 
4637 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4638   if (ref.is_narrow()) {
4639     return verify_ref((narrowOop*) ref);
4640   } else {
4641     return verify_ref((oop*) ref);
4642   }
4643 }
4644 #endif // ASSERT
4645 
4646 void G1ParScanThreadState::trim_queue() {
4647   assert(_evac_cl != NULL, "not set");
4648   assert(_evac_failure_cl != NULL, "not set");
4649   assert(_partial_scan_cl != NULL, "not set");
4650 
4651   StarTask ref;
4652   do {
4653     // Drain the overflow stack first, so other threads can steal.
4654     while (refs()->pop_overflow(ref)) {
4655       deal_with_reference(ref);
4656     }
4657 
4658     while (refs()->pop_local(ref)) {
4659       deal_with_reference(ref);
4660     }
4661   } while (!refs()->is_empty());
4662 }
4663 
4664 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4665                                      G1ParScanThreadState* par_scan_state) :
4666   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4667   _par_scan_state(par_scan_state),
4668   _worker_id(par_scan_state->queue_num()),
4669   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4670   _mark_in_progress(_g1->mark_in_progress()) { }
4671 
4672 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4673 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4674 #ifdef ASSERT
4675   HeapRegion* hr = _g1->heap_region_containing(obj);
4676   assert(hr != NULL, "sanity");
4677   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4678 #endif // ASSERT
4679 
4680   // We know that the object is not moving so it's safe to read its size.
4681   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4682 }
4683 
4684 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4685 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4686   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4687 #ifdef ASSERT
4688   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4689   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4690   assert(from_obj != to_obj, "should not be self-forwarded");
4691 
4692   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4693   assert(from_hr != NULL, "sanity");
4694   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4695 
4696   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4697   assert(to_hr != NULL, "sanity");
4698   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4699 #endif // ASSERT
4700 
4701   // The object might be in the process of being copied by another
4702   // worker so we cannot trust that its to-space image is
4703   // well-formed. So we have to read its size from its from-space
4704   // image which we know should not be changing.
4705   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4706 }
4707 
4708 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4709 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4710   ::copy_to_survivor_space(oop old) {
4711   size_t word_sz = old->size();
4712   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4713   // +1 to make the -1 indexes valid...
4714   int       young_index = from_region->young_index_in_cset()+1;
4715   assert( (from_region->is_young() && young_index >  0) ||
4716          (!from_region->is_young() && young_index == 0), "invariant" );
4717   G1CollectorPolicy* g1p = _g1->g1_policy();
4718   markOop m = old->mark();
4719   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4720                                            : m->age();
4721   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4722                                                              word_sz);
4723   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4724 #ifndef PRODUCT
4725   // Should this evacuation fail?
4726   if (_g1->evacuation_should_fail()) {
4727     if (obj_ptr != NULL) {
4728       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4729       obj_ptr = NULL;
4730     }
4731   }
4732 #endif // !PRODUCT
4733 
4734   if (obj_ptr == NULL) {
4735     // This will either forward-to-self, or detect that someone else has
4736     // installed a forwarding pointer.
4737     return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4738   }
4739 
4740   oop obj = oop(obj_ptr);
4741 
4742   // We're going to allocate linearly, so might as well prefetch ahead.
4743   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4744 
4745   oop forward_ptr = old->forward_to_atomic(obj);
4746   if (forward_ptr == NULL) {
4747     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4748     if (g1p->track_object_age(alloc_purpose)) {
4749       // We could simply do obj->incr_age(). However, this causes a
4750       // performance issue. obj->incr_age() will first check whether
4751       // the object has a displaced mark by checking its mark word;
4752       // getting the mark word from the new location of the object
4753       // stalls. So, given that we already have the mark word and we
4754       // are about to install it anyway, it's better to increase the
4755       // age on the mark word, when the object does not have a
4756       // displaced mark word. We're not expecting many objects to have
4757       // a displaced marked word, so that case is not optimized
4758       // further (it could be...) and we simply call obj->incr_age().
4759 
4760       if (m->has_displaced_mark_helper()) {
4761         // in this case, we have to install the mark word first,
4762         // otherwise obj looks to be forwarded (the old mark word,
4763         // which contains the forward pointer, was copied)
4764         obj->set_mark(m);
4765         obj->incr_age();
4766       } else {
4767         m = m->incr_age();
4768         obj->set_mark(m);
4769       }
4770       _par_scan_state->age_table()->add(obj, word_sz);
4771     } else {
4772       obj->set_mark(m);
4773     }
4774 
4775     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4776     surv_young_words[young_index] += word_sz;
4777 
4778     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4779       // We keep track of the next start index in the length field of
4780       // the to-space object. The actual length can be found in the
4781       // length field of the from-space object.
4782       arrayOop(obj)->set_length(0);
4783       oop* old_p = set_partial_array_mask(old);
4784       _par_scan_state->push_on_queue(old_p);
4785     } else {
4786       // No point in using the slower heap_region_containing() method,
4787       // given that we know obj is in the heap.
4788       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4789       obj->oop_iterate_backwards(&_scanner);
4790     }
4791   } else {
4792     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4793     obj = forward_ptr;
4794   }
4795   return obj;
4796 }
4797 
4798 template <class T>
4799 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4800   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4801     _scanned_klass->record_modified_oops();
4802   }
4803 }
4804 
4805 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4806 template <class T>
4807 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4808 ::do_oop_work(T* p) {
4809   oop obj = oopDesc::load_decode_heap_oop(p);
4810   assert(barrier != G1BarrierRS || obj != NULL,
4811          "Precondition: G1BarrierRS implies obj is non-NULL");
4812 
4813   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4814 
4815   // here the null check is implicit in the cset_fast_test() test
4816   if (_g1->in_cset_fast_test(obj)) {
4817     oop forwardee;
4818     if (obj->is_forwarded()) {
4819       forwardee = obj->forwardee();
4820     } else {
4821       forwardee = copy_to_survivor_space(obj);
4822     }
4823     assert(forwardee != NULL, "forwardee should not be NULL");
4824     oopDesc::encode_store_heap_oop(p, forwardee);
4825     if (do_mark_object && forwardee != obj) {
4826       // If the object is self-forwarded we don't need to explicitly
4827       // mark it, the evacuation failure protocol will do so.
4828       mark_forwarded_object(obj, forwardee);
4829     }
4830 
4831     // When scanning the RS, we only care about objs in CS.
4832     if (barrier == G1BarrierRS) {
4833       _par_scan_state->update_rs(_from, p, _worker_id);
4834     } else if (barrier == G1BarrierKlass) {
4835       do_klass_barrier(p, forwardee);
4836     }
4837   } else {
4838     // The object is not in collection set. If we're a root scanning
4839     // closure during an initial mark pause (i.e. do_mark_object will
4840     // be true) then attempt to mark the object.
4841     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4842       mark_object(obj);
4843     }
4844   }
4845 
4846   if (barrier == G1BarrierEvac && obj != NULL) {
4847     _par_scan_state->update_rs(_from, p, _worker_id);
4848   }
4849 
4850   if (do_gen_barrier && obj != NULL) {
4851     par_do_barrier(p);
4852   }
4853 }
4854 
4855 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4856 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4857 
4858 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4859   assert(has_partial_array_mask(p), "invariant");
4860   oop from_obj = clear_partial_array_mask(p);
4861 
4862   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4863   assert(from_obj->is_objArray(), "must be obj array");
4864   objArrayOop from_obj_array = objArrayOop(from_obj);
4865   // The from-space object contains the real length.
4866   int length                 = from_obj_array->length();
4867 
4868   assert(from_obj->is_forwarded(), "must be forwarded");
4869   oop to_obj                 = from_obj->forwardee();
4870   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4871   objArrayOop to_obj_array   = objArrayOop(to_obj);
4872   // We keep track of the next start index in the length field of the
4873   // to-space object.
4874   int next_index             = to_obj_array->length();
4875   assert(0 <= next_index && next_index < length,
4876          err_msg("invariant, next index: %d, length: %d", next_index, length));
4877 
4878   int start                  = next_index;
4879   int end                    = length;
4880   int remainder              = end - start;
4881   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4882   if (remainder > 2 * ParGCArrayScanChunk) {
4883     end = start + ParGCArrayScanChunk;
4884     to_obj_array->set_length(end);
4885     // Push the remainder before we process the range in case another
4886     // worker has run out of things to do and can steal it.
4887     oop* from_obj_p = set_partial_array_mask(from_obj);
4888     _par_scan_state->push_on_queue(from_obj_p);
4889   } else {
4890     assert(length == end, "sanity");
4891     // We'll process the final range for this object. Restore the length
4892     // so that the heap remains parsable in case of evacuation failure.
4893     to_obj_array->set_length(end);
4894   }
4895   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4896   // Process indexes [start,end). It will also process the header
4897   // along with the first chunk (i.e., the chunk with start == 0).
4898   // Note that at this point the length field of to_obj_array is not
4899   // correct given that we are using it to keep track of the next
4900   // start index. oop_iterate_range() (thankfully!) ignores the length
4901   // field and only relies on the start / end parameters.  It does
4902   // however return the size of the object which will be incorrect. So
4903   // we have to ignore it even if we wanted to use it.
4904   to_obj_array->oop_iterate_range(&_scanner, start, end);
4905 }
4906 
4907 class G1ParEvacuateFollowersClosure : public VoidClosure {
4908 protected:
4909   G1CollectedHeap*              _g1h;
4910   G1ParScanThreadState*         _par_scan_state;
4911   RefToScanQueueSet*            _queues;
4912   ParallelTaskTerminator*       _terminator;
4913 
4914   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4915   RefToScanQueueSet*      queues()         { return _queues; }
4916   ParallelTaskTerminator* terminator()     { return _terminator; }
4917 
4918 public:
4919   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4920                                 G1ParScanThreadState* par_scan_state,
4921                                 RefToScanQueueSet* queues,
4922                                 ParallelTaskTerminator* terminator)
4923     : _g1h(g1h), _par_scan_state(par_scan_state),
4924       _queues(queues), _terminator(terminator) {}
4925 
4926   void do_void();
4927 
4928 private:
4929   inline bool offer_termination();
4930 };
4931 
4932 bool G1ParEvacuateFollowersClosure::offer_termination() {
4933   G1ParScanThreadState* const pss = par_scan_state();
4934   pss->start_term_time();
4935   const bool res = terminator()->offer_termination();
4936   pss->end_term_time();
4937   return res;
4938 }
4939 
4940 void G1ParEvacuateFollowersClosure::do_void() {
4941   StarTask stolen_task;
4942   G1ParScanThreadState* const pss = par_scan_state();
4943   pss->trim_queue();
4944 
4945   do {
4946     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4947       assert(pss->verify_task(stolen_task), "sanity");
4948       if (stolen_task.is_narrow()) {
4949         pss->deal_with_reference((narrowOop*) stolen_task);
4950       } else {
4951         pss->deal_with_reference((oop*) stolen_task);
4952       }
4953 
4954       // We've just processed a reference and we might have made
4955       // available new entries on the queues. So we have to make sure
4956       // we drain the queues as necessary.
4957       pss->trim_queue();
4958     }
4959   } while (!offer_termination());
4960 
4961   pss->retire_alloc_buffers();
4962 }
4963 
4964 class G1KlassScanClosure : public KlassClosure {
4965  G1ParCopyHelper* _closure;
4966  bool             _process_only_dirty;
4967  int              _count;
4968  public:
4969   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4970       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4971   void do_klass(Klass* klass) {
4972     // If the klass has not been dirtied we know that there's
4973     // no references into  the young gen and we can skip it.
4974    if (!_process_only_dirty || klass->has_modified_oops()) {
4975       // Clean the klass since we're going to scavenge all the metadata.
4976       klass->clear_modified_oops();
4977 
4978       // Tell the closure that this klass is the Klass to scavenge
4979       // and is the one to dirty if oops are left pointing into the young gen.
4980       _closure->set_scanned_klass(klass);
4981 
4982       klass->oops_do(_closure);
4983 
4984       _closure->set_scanned_klass(NULL);
4985     }
4986     _count++;
4987   }
4988 };
4989 
4990 class G1ParTask : public AbstractGangTask {
4991 protected:
4992   G1CollectedHeap*       _g1h;
4993   RefToScanQueueSet      *_queues;
4994   ParallelTaskTerminator _terminator;
4995   uint _n_workers;
4996 
4997   Mutex _stats_lock;
4998   Mutex* stats_lock() { return &_stats_lock; }
4999 
5000   size_t getNCards() {
5001     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5002       / G1BlockOffsetSharedArray::N_bytes;
5003   }
5004 
5005 public:
5006   G1ParTask(G1CollectedHeap* g1h,
5007             RefToScanQueueSet *task_queues)
5008     : AbstractGangTask("G1 collection"),
5009       _g1h(g1h),
5010       _queues(task_queues),
5011       _terminator(0, _queues),
5012       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
5013   {}
5014 
5015   RefToScanQueueSet* queues() { return _queues; }
5016 
5017   RefToScanQueue *work_queue(int i) {
5018     return queues()->queue(i);
5019   }
5020 
5021   ParallelTaskTerminator* terminator() { return &_terminator; }
5022 
5023   virtual void set_for_termination(int active_workers) {
5024     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5025     // in the young space (_par_seq_tasks) in the G1 heap
5026     // for SequentialSubTasksDone.
5027     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5028     // both of which need setting by set_n_termination().
5029     _g1h->SharedHeap::set_n_termination(active_workers);
5030     _g1h->set_n_termination(active_workers);
5031     terminator()->reset_for_reuse(active_workers);
5032     _n_workers = active_workers;
5033   }
5034 
5035   void work(uint worker_id) {
5036     if (worker_id >= _n_workers) return;  // no work needed this round
5037 
5038     double start_time_ms = os::elapsedTime() * 1000.0;
5039     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5040 
5041     {
5042       ResourceMark rm;
5043       HandleMark   hm;
5044 
5045       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
5046 
5047       G1ParScanThreadState            pss(_g1h, worker_id);
5048       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
5049       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5050       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
5051 
5052       pss.set_evac_closure(&scan_evac_cl);
5053       pss.set_evac_failure_closure(&evac_failure_cl);
5054       pss.set_partial_scan_closure(&partial_scan_cl);
5055 
5056       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
5057       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
5058 
5059       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5060       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5061 
5062       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
5063       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5064       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5065 
5066       OopClosure*                    scan_root_cl = &only_scan_root_cl;
5067       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
5068 
5069       if (_g1h->g1_policy()->during_initial_mark_pause()) {
5070         // We also need to mark copied objects.
5071         scan_root_cl = &scan_mark_root_cl;
5072         scan_klasses_cl = &scan_mark_klasses_cl_s;
5073       }
5074 
5075       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
5076 
5077       // Don't scan the scavengable methods in the code cache as part
5078       // of strong root scanning. The code roots that point into a
5079       // region in the collection set are scanned when we scan the
5080       // region's RSet.
5081       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5082 
5083       pss.start_strong_roots();
5084       _g1h->g1_process_strong_roots(/* is scavenging */ true,
5085                                     SharedHeap::ScanningOption(so),
5086                                     scan_root_cl,
5087                                     &push_heap_rs_cl,
5088                                     scan_klasses_cl,
5089                                     worker_id);
5090       pss.end_strong_roots();
5091 
5092       {
5093         double start = os::elapsedTime();
5094         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5095         evac.do_void();
5096         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5097         double term_ms = pss.term_time()*1000.0;
5098         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5099         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5100       }
5101       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5102       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5103 
5104       if (ParallelGCVerbose) {
5105         MutexLocker x(stats_lock());
5106         pss.print_termination_stats(worker_id);
5107       }
5108 
5109       assert(pss.refs()->is_empty(), "should be empty");
5110 
5111       // Close the inner scope so that the ResourceMark and HandleMark
5112       // destructors are executed here and are included as part of the
5113       // "GC Worker Time".
5114     }
5115 
5116     double end_time_ms = os::elapsedTime() * 1000.0;
5117     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5118   }
5119 };
5120 
5121 // *** Common G1 Evacuation Stuff
5122 
5123 // This method is run in a GC worker.
5124 
5125 void
5126 G1CollectedHeap::
5127 g1_process_strong_roots(bool is_scavenging,
5128                         ScanningOption so,
5129                         OopClosure* scan_non_heap_roots,
5130                         OopsInHeapRegionClosure* scan_rs,
5131                         G1KlassScanClosure* scan_klasses,
5132                         int worker_i) {
5133 
5134   // First scan the strong roots
5135   double ext_roots_start = os::elapsedTime();
5136   double closure_app_time_sec = 0.0;
5137 
5138   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5139 
5140   assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5141   // Walk the code cache/strong code roots w/o buffering, because StarTask
5142   // cannot handle unaligned oop locations.
5143   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5144 
5145   process_strong_roots(false, // no scoping; this is parallel code
5146                        is_scavenging, so,
5147                        &buf_scan_non_heap_roots,
5148                        &eager_scan_code_roots,
5149                        scan_klasses
5150                        );
5151 
5152   // Now the CM ref_processor roots.
5153   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5154     // We need to treat the discovered reference lists of the
5155     // concurrent mark ref processor as roots and keep entries
5156     // (which are added by the marking threads) on them live
5157     // until they can be processed at the end of marking.
5158     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5159   }
5160 
5161   // Finish up any enqueued closure apps (attributed as object copy time).
5162   buf_scan_non_heap_roots.done();
5163 
5164   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5165 
5166   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5167 
5168   double ext_root_time_ms =
5169     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5170 
5171   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5172 
5173   // During conc marking we have to filter the per-thread SATB buffers
5174   // to make sure we remove any oops into the CSet (which will show up
5175   // as implicitly live).
5176   double satb_filtering_ms = 0.0;
5177   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5178     if (mark_in_progress()) {
5179       double satb_filter_start = os::elapsedTime();
5180 
5181       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5182 
5183       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5184     }
5185   }
5186   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5187 
5188   // If this is an initial mark pause, and we're not scanning
5189   // the entire code cache, we need to mark the oops in the
5190   // strong code root lists for the regions that are not in
5191   // the collection set.
5192   // Note all threads participate in this set of root tasks.
5193   double mark_strong_code_roots_ms = 0.0;
5194   if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5195     double mark_strong_roots_start = os::elapsedTime();
5196     mark_strong_code_roots(worker_i);
5197     mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5198   }
5199   g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5200 
5201   // Now scan the complement of the collection set.
5202   if (scan_rs != NULL) {
5203     g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5204   }
5205   _process_strong_tasks->all_tasks_completed();
5206 }
5207 
5208 void
5209 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5210   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5211   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5212 }
5213 
5214 // Weak Reference Processing support
5215 
5216 // An always "is_alive" closure that is used to preserve referents.
5217 // If the object is non-null then it's alive.  Used in the preservation
5218 // of referent objects that are pointed to by reference objects
5219 // discovered by the CM ref processor.
5220 class G1AlwaysAliveClosure: public BoolObjectClosure {
5221   G1CollectedHeap* _g1;
5222 public:
5223   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5224   bool do_object_b(oop p) {
5225     if (p != NULL) {
5226       return true;
5227     }
5228     return false;
5229   }
5230 };
5231 
5232 bool G1STWIsAliveClosure::do_object_b(oop p) {
5233   // An object is reachable if it is outside the collection set,
5234   // or is inside and copied.
5235   return !_g1->obj_in_cs(p) || p->is_forwarded();
5236 }
5237 
5238 // Non Copying Keep Alive closure
5239 class G1KeepAliveClosure: public OopClosure {
5240   G1CollectedHeap* _g1;
5241 public:
5242   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5243   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5244   void do_oop(      oop* p) {
5245     oop obj = *p;
5246 
5247     if (_g1->obj_in_cs(obj)) {
5248       assert( obj->is_forwarded(), "invariant" );
5249       *p = obj->forwardee();
5250     }
5251   }
5252 };
5253 
5254 // Copying Keep Alive closure - can be called from both
5255 // serial and parallel code as long as different worker
5256 // threads utilize different G1ParScanThreadState instances
5257 // and different queues.
5258 
5259 class G1CopyingKeepAliveClosure: public OopClosure {
5260   G1CollectedHeap*         _g1h;
5261   OopClosure*              _copy_non_heap_obj_cl;
5262   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5263   G1ParScanThreadState*    _par_scan_state;
5264 
5265 public:
5266   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5267                             OopClosure* non_heap_obj_cl,
5268                             OopsInHeapRegionClosure* metadata_obj_cl,
5269                             G1ParScanThreadState* pss):
5270     _g1h(g1h),
5271     _copy_non_heap_obj_cl(non_heap_obj_cl),
5272     _copy_metadata_obj_cl(metadata_obj_cl),
5273     _par_scan_state(pss)
5274   {}
5275 
5276   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5277   virtual void do_oop(      oop* p) { do_oop_work(p); }
5278 
5279   template <class T> void do_oop_work(T* p) {
5280     oop obj = oopDesc::load_decode_heap_oop(p);
5281 
5282     if (_g1h->obj_in_cs(obj)) {
5283       // If the referent object has been forwarded (either copied
5284       // to a new location or to itself in the event of an
5285       // evacuation failure) then we need to update the reference
5286       // field and, if both reference and referent are in the G1
5287       // heap, update the RSet for the referent.
5288       //
5289       // If the referent has not been forwarded then we have to keep
5290       // it alive by policy. Therefore we have copy the referent.
5291       //
5292       // If the reference field is in the G1 heap then we can push
5293       // on the PSS queue. When the queue is drained (after each
5294       // phase of reference processing) the object and it's followers
5295       // will be copied, the reference field set to point to the
5296       // new location, and the RSet updated. Otherwise we need to
5297       // use the the non-heap or metadata closures directly to copy
5298       // the referent object and update the pointer, while avoiding
5299       // updating the RSet.
5300 
5301       if (_g1h->is_in_g1_reserved(p)) {
5302         _par_scan_state->push_on_queue(p);
5303       } else {
5304         assert(!ClassLoaderDataGraph::contains((address)p),
5305                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5306                               PTR_FORMAT, p));
5307           _copy_non_heap_obj_cl->do_oop(p);
5308         }
5309       }
5310     }
5311 };
5312 
5313 // Serial drain queue closure. Called as the 'complete_gc'
5314 // closure for each discovered list in some of the
5315 // reference processing phases.
5316 
5317 class G1STWDrainQueueClosure: public VoidClosure {
5318 protected:
5319   G1CollectedHeap* _g1h;
5320   G1ParScanThreadState* _par_scan_state;
5321 
5322   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5323 
5324 public:
5325   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5326     _g1h(g1h),
5327     _par_scan_state(pss)
5328   { }
5329 
5330   void do_void() {
5331     G1ParScanThreadState* const pss = par_scan_state();
5332     pss->trim_queue();
5333   }
5334 };
5335 
5336 // Parallel Reference Processing closures
5337 
5338 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5339 // processing during G1 evacuation pauses.
5340 
5341 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5342 private:
5343   G1CollectedHeap*   _g1h;
5344   RefToScanQueueSet* _queues;
5345   FlexibleWorkGang*  _workers;
5346   int                _active_workers;
5347 
5348 public:
5349   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5350                         FlexibleWorkGang* workers,
5351                         RefToScanQueueSet *task_queues,
5352                         int n_workers) :
5353     _g1h(g1h),
5354     _queues(task_queues),
5355     _workers(workers),
5356     _active_workers(n_workers)
5357   {
5358     assert(n_workers > 0, "shouldn't call this otherwise");
5359   }
5360 
5361   // Executes the given task using concurrent marking worker threads.
5362   virtual void execute(ProcessTask& task);
5363   virtual void execute(EnqueueTask& task);
5364 };
5365 
5366 // Gang task for possibly parallel reference processing
5367 
5368 class G1STWRefProcTaskProxy: public AbstractGangTask {
5369   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5370   ProcessTask&     _proc_task;
5371   G1CollectedHeap* _g1h;
5372   RefToScanQueueSet *_task_queues;
5373   ParallelTaskTerminator* _terminator;
5374 
5375 public:
5376   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5377                      G1CollectedHeap* g1h,
5378                      RefToScanQueueSet *task_queues,
5379                      ParallelTaskTerminator* terminator) :
5380     AbstractGangTask("Process reference objects in parallel"),
5381     _proc_task(proc_task),
5382     _g1h(g1h),
5383     _task_queues(task_queues),
5384     _terminator(terminator)
5385   {}
5386 
5387   virtual void work(uint worker_id) {
5388     // The reference processing task executed by a single worker.
5389     ResourceMark rm;
5390     HandleMark   hm;
5391 
5392     G1STWIsAliveClosure is_alive(_g1h);
5393 
5394     G1ParScanThreadState pss(_g1h, worker_id);
5395 
5396     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5397     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5398     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5399 
5400     pss.set_evac_closure(&scan_evac_cl);
5401     pss.set_evac_failure_closure(&evac_failure_cl);
5402     pss.set_partial_scan_closure(&partial_scan_cl);
5403 
5404     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5405     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5406 
5407     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5408     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5409 
5410     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5411     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5412 
5413     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5414       // We also need to mark copied objects.
5415       copy_non_heap_cl = &copy_mark_non_heap_cl;
5416       copy_metadata_cl = &copy_mark_metadata_cl;
5417     }
5418 
5419     // Keep alive closure.
5420     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5421 
5422     // Complete GC closure
5423     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5424 
5425     // Call the reference processing task's work routine.
5426     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5427 
5428     // Note we cannot assert that the refs array is empty here as not all
5429     // of the processing tasks (specifically phase2 - pp2_work) execute
5430     // the complete_gc closure (which ordinarily would drain the queue) so
5431     // the queue may not be empty.
5432   }
5433 };
5434 
5435 // Driver routine for parallel reference processing.
5436 // Creates an instance of the ref processing gang
5437 // task and has the worker threads execute it.
5438 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5439   assert(_workers != NULL, "Need parallel worker threads.");
5440 
5441   ParallelTaskTerminator terminator(_active_workers, _queues);
5442   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5443 
5444   _g1h->set_par_threads(_active_workers);
5445   _workers->run_task(&proc_task_proxy);
5446   _g1h->set_par_threads(0);
5447 }
5448 
5449 // Gang task for parallel reference enqueueing.
5450 
5451 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5452   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5453   EnqueueTask& _enq_task;
5454 
5455 public:
5456   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5457     AbstractGangTask("Enqueue reference objects in parallel"),
5458     _enq_task(enq_task)
5459   { }
5460 
5461   virtual void work(uint worker_id) {
5462     _enq_task.work(worker_id);
5463   }
5464 };
5465 
5466 // Driver routine for parallel reference enqueueing.
5467 // Creates an instance of the ref enqueueing gang
5468 // task and has the worker threads execute it.
5469 
5470 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5471   assert(_workers != NULL, "Need parallel worker threads.");
5472 
5473   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5474 
5475   _g1h->set_par_threads(_active_workers);
5476   _workers->run_task(&enq_task_proxy);
5477   _g1h->set_par_threads(0);
5478 }
5479 
5480 // End of weak reference support closures
5481 
5482 // Abstract task used to preserve (i.e. copy) any referent objects
5483 // that are in the collection set and are pointed to by reference
5484 // objects discovered by the CM ref processor.
5485 
5486 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5487 protected:
5488   G1CollectedHeap* _g1h;
5489   RefToScanQueueSet      *_queues;
5490   ParallelTaskTerminator _terminator;
5491   uint _n_workers;
5492 
5493 public:
5494   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5495     AbstractGangTask("ParPreserveCMReferents"),
5496     _g1h(g1h),
5497     _queues(task_queues),
5498     _terminator(workers, _queues),
5499     _n_workers(workers)
5500   { }
5501 
5502   void work(uint worker_id) {
5503     ResourceMark rm;
5504     HandleMark   hm;
5505 
5506     G1ParScanThreadState            pss(_g1h, worker_id);
5507     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5508     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5509     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5510 
5511     pss.set_evac_closure(&scan_evac_cl);
5512     pss.set_evac_failure_closure(&evac_failure_cl);
5513     pss.set_partial_scan_closure(&partial_scan_cl);
5514 
5515     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5516 
5517 
5518     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5519     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5520 
5521     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5522     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5523 
5524     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5525     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5526 
5527     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5528       // We also need to mark copied objects.
5529       copy_non_heap_cl = &copy_mark_non_heap_cl;
5530       copy_metadata_cl = &copy_mark_metadata_cl;
5531     }
5532 
5533     // Is alive closure
5534     G1AlwaysAliveClosure always_alive(_g1h);
5535 
5536     // Copying keep alive closure. Applied to referent objects that need
5537     // to be copied.
5538     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5539 
5540     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5541 
5542     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5543     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5544 
5545     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5546     // So this must be true - but assert just in case someone decides to
5547     // change the worker ids.
5548     assert(0 <= worker_id && worker_id < limit, "sanity");
5549     assert(!rp->discovery_is_atomic(), "check this code");
5550 
5551     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5552     for (uint idx = worker_id; idx < limit; idx += stride) {
5553       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5554 
5555       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5556       while (iter.has_next()) {
5557         // Since discovery is not atomic for the CM ref processor, we
5558         // can see some null referent objects.
5559         iter.load_ptrs(DEBUG_ONLY(true));
5560         oop ref = iter.obj();
5561 
5562         // This will filter nulls.
5563         if (iter.is_referent_alive()) {
5564           iter.make_referent_alive();
5565         }
5566         iter.move_to_next();
5567       }
5568     }
5569 
5570     // Drain the queue - which may cause stealing
5571     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5572     drain_queue.do_void();
5573     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5574     assert(pss.refs()->is_empty(), "should be");
5575   }
5576 };
5577 
5578 // Weak Reference processing during an evacuation pause (part 1).
5579 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5580   double ref_proc_start = os::elapsedTime();
5581 
5582   ReferenceProcessor* rp = _ref_processor_stw;
5583   assert(rp->discovery_enabled(), "should have been enabled");
5584 
5585   // Any reference objects, in the collection set, that were 'discovered'
5586   // by the CM ref processor should have already been copied (either by
5587   // applying the external root copy closure to the discovered lists, or
5588   // by following an RSet entry).
5589   //
5590   // But some of the referents, that are in the collection set, that these
5591   // reference objects point to may not have been copied: the STW ref
5592   // processor would have seen that the reference object had already
5593   // been 'discovered' and would have skipped discovering the reference,
5594   // but would not have treated the reference object as a regular oop.
5595   // As a result the copy closure would not have been applied to the
5596   // referent object.
5597   //
5598   // We need to explicitly copy these referent objects - the references
5599   // will be processed at the end of remarking.
5600   //
5601   // We also need to do this copying before we process the reference
5602   // objects discovered by the STW ref processor in case one of these
5603   // referents points to another object which is also referenced by an
5604   // object discovered by the STW ref processor.
5605 
5606   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5607            no_of_gc_workers == workers()->active_workers(),
5608            "Need to reset active GC workers");
5609 
5610   set_par_threads(no_of_gc_workers);
5611   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5612                                                  no_of_gc_workers,
5613                                                  _task_queues);
5614 
5615   if (G1CollectedHeap::use_parallel_gc_threads()) {
5616     workers()->run_task(&keep_cm_referents);
5617   } else {
5618     keep_cm_referents.work(0);
5619   }
5620 
5621   set_par_threads(0);
5622 
5623   // Closure to test whether a referent is alive.
5624   G1STWIsAliveClosure is_alive(this);
5625 
5626   // Even when parallel reference processing is enabled, the processing
5627   // of JNI refs is serial and performed serially by the current thread
5628   // rather than by a worker. The following PSS will be used for processing
5629   // JNI refs.
5630 
5631   // Use only a single queue for this PSS.
5632   G1ParScanThreadState pss(this, 0);
5633 
5634   // We do not embed a reference processor in the copying/scanning
5635   // closures while we're actually processing the discovered
5636   // reference objects.
5637   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5638   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5639   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5640 
5641   pss.set_evac_closure(&scan_evac_cl);
5642   pss.set_evac_failure_closure(&evac_failure_cl);
5643   pss.set_partial_scan_closure(&partial_scan_cl);
5644 
5645   assert(pss.refs()->is_empty(), "pre-condition");
5646 
5647   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5648   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5649 
5650   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5651   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5652 
5653   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5654   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5655 
5656   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5657     // We also need to mark copied objects.
5658     copy_non_heap_cl = &copy_mark_non_heap_cl;
5659     copy_metadata_cl = &copy_mark_metadata_cl;
5660   }
5661 
5662   // Keep alive closure.
5663   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5664 
5665   // Serial Complete GC closure
5666   G1STWDrainQueueClosure drain_queue(this, &pss);
5667 
5668   // Setup the soft refs policy...
5669   rp->setup_policy(false);
5670 
5671   ReferenceProcessorStats stats;
5672   if (!rp->processing_is_mt()) {
5673     // Serial reference processing...
5674     stats = rp->process_discovered_references(&is_alive,
5675                                               &keep_alive,
5676                                               &drain_queue,
5677                                               NULL,
5678                                               _gc_timer_stw);
5679   } else {
5680     // Parallel reference processing
5681     assert(rp->num_q() == no_of_gc_workers, "sanity");
5682     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5683 
5684     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5685     stats = rp->process_discovered_references(&is_alive,
5686                                               &keep_alive,
5687                                               &drain_queue,
5688                                               &par_task_executor,
5689                                               _gc_timer_stw);
5690   }
5691 
5692   _gc_tracer_stw->report_gc_reference_stats(stats);
5693   // We have completed copying any necessary live referent objects
5694   // (that were not copied during the actual pause) so we can
5695   // retire any active alloc buffers
5696   pss.retire_alloc_buffers();
5697   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5698 
5699   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5700   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5701 }
5702 
5703 // Weak Reference processing during an evacuation pause (part 2).
5704 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5705   double ref_enq_start = os::elapsedTime();
5706 
5707   ReferenceProcessor* rp = _ref_processor_stw;
5708   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5709 
5710   // Now enqueue any remaining on the discovered lists on to
5711   // the pending list.
5712   if (!rp->processing_is_mt()) {
5713     // Serial reference processing...
5714     rp->enqueue_discovered_references();
5715   } else {
5716     // Parallel reference enqueueing
5717 
5718     assert(no_of_gc_workers == workers()->active_workers(),
5719            "Need to reset active workers");
5720     assert(rp->num_q() == no_of_gc_workers, "sanity");
5721     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5722 
5723     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5724     rp->enqueue_discovered_references(&par_task_executor);
5725   }
5726 
5727   rp->verify_no_references_recorded();
5728   assert(!rp->discovery_enabled(), "should have been disabled");
5729 
5730   // FIXME
5731   // CM's reference processing also cleans up the string and symbol tables.
5732   // Should we do that here also? We could, but it is a serial operation
5733   // and could significantly increase the pause time.
5734 
5735   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5736   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5737 }
5738 
5739 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5740   _expand_heap_after_alloc_failure = true;
5741   _evacuation_failed = false;
5742 
5743   // Should G1EvacuationFailureALot be in effect for this GC?
5744   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5745 
5746   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5747 
5748   // Disable the hot card cache.
5749   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5750   hot_card_cache->reset_hot_cache_claimed_index();
5751   hot_card_cache->set_use_cache(false);
5752 
5753   uint n_workers;
5754   if (G1CollectedHeap::use_parallel_gc_threads()) {
5755     n_workers =
5756       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5757                                      workers()->active_workers(),
5758                                      Threads::number_of_non_daemon_threads());
5759     assert(UseDynamicNumberOfGCThreads ||
5760            n_workers == workers()->total_workers(),
5761            "If not dynamic should be using all the  workers");
5762     workers()->set_active_workers(n_workers);
5763     set_par_threads(n_workers);
5764   } else {
5765     assert(n_par_threads() == 0,
5766            "Should be the original non-parallel value");
5767     n_workers = 1;
5768   }
5769 
5770   G1ParTask g1_par_task(this, _task_queues);
5771 
5772   init_for_evac_failure(NULL);
5773 
5774   rem_set()->prepare_for_younger_refs_iterate(true);
5775 
5776   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5777   double start_par_time_sec = os::elapsedTime();
5778   double end_par_time_sec;
5779 
5780   {
5781     StrongRootsScope srs(this);
5782 
5783     if (G1CollectedHeap::use_parallel_gc_threads()) {
5784       // The individual threads will set their evac-failure closures.
5785       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5786       // These tasks use ShareHeap::_process_strong_tasks
5787       assert(UseDynamicNumberOfGCThreads ||
5788              workers()->active_workers() == workers()->total_workers(),
5789              "If not dynamic should be using all the  workers");
5790       workers()->run_task(&g1_par_task);
5791     } else {
5792       g1_par_task.set_for_termination(n_workers);
5793       g1_par_task.work(0);
5794     }
5795     end_par_time_sec = os::elapsedTime();
5796 
5797     // Closing the inner scope will execute the destructor
5798     // for the StrongRootsScope object. We record the current
5799     // elapsed time before closing the scope so that time
5800     // taken for the SRS destructor is NOT included in the
5801     // reported parallel time.
5802   }
5803 
5804   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5805   g1_policy()->phase_times()->record_par_time(par_time_ms);
5806 
5807   double code_root_fixup_time_ms =
5808         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5809   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5810 
5811   set_par_threads(0);
5812 
5813   // Process any discovered reference objects - we have
5814   // to do this _before_ we retire the GC alloc regions
5815   // as we may have to copy some 'reachable' referent
5816   // objects (and their reachable sub-graphs) that were
5817   // not copied during the pause.
5818   process_discovered_references(n_workers);
5819 
5820   // Weak root processing.
5821   {
5822     G1STWIsAliveClosure is_alive(this);
5823     G1KeepAliveClosure keep_alive(this);
5824     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5825   }
5826 
5827   release_gc_alloc_regions(n_workers, evacuation_info);
5828   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5829 
5830   // Reset and re-enable the hot card cache.
5831   // Note the counts for the cards in the regions in the
5832   // collection set are reset when the collection set is freed.
5833   hot_card_cache->reset_hot_cache();
5834   hot_card_cache->set_use_cache(true);
5835 
5836   // Migrate the strong code roots attached to each region in
5837   // the collection set. Ideally we would like to do this
5838   // after we have finished the scanning/evacuation of the
5839   // strong code roots for a particular heap region.
5840   migrate_strong_code_roots();
5841 
5842   if (g1_policy()->during_initial_mark_pause()) {
5843     // Reset the claim values set during marking the strong code roots
5844     reset_heap_region_claim_values();
5845   }
5846 
5847   finalize_for_evac_failure();
5848 
5849   if (evacuation_failed()) {
5850     remove_self_forwarding_pointers();
5851 
5852     // Reset the G1EvacuationFailureALot counters and flags
5853     // Note: the values are reset only when an actual
5854     // evacuation failure occurs.
5855     NOT_PRODUCT(reset_evacuation_should_fail();)
5856   }
5857 
5858   // Enqueue any remaining references remaining on the STW
5859   // reference processor's discovered lists. We need to do
5860   // this after the card table is cleaned (and verified) as
5861   // the act of enqueueing entries on to the pending list
5862   // will log these updates (and dirty their associated
5863   // cards). We need these updates logged to update any
5864   // RSets.
5865   enqueue_discovered_references(n_workers);
5866 
5867   if (G1DeferredRSUpdate) {
5868     RedirtyLoggedCardTableEntryFastClosure redirty;
5869     dirty_card_queue_set().set_closure(&redirty);
5870     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5871 
5872     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5873     dcq.merge_bufferlists(&dirty_card_queue_set());
5874     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5875   }
5876   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5877 }
5878 
5879 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5880                                      size_t* pre_used,
5881                                      FreeRegionList* free_list,
5882                                      OldRegionSet* old_proxy_set,
5883                                      HumongousRegionSet* humongous_proxy_set,
5884                                      HRRSCleanupTask* hrrs_cleanup_task,
5885                                      bool par) {
5886   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5887     if (hr->isHumongous()) {
5888       assert(hr->startsHumongous(), "we should only see starts humongous");
5889       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5890     } else {
5891       _old_set.remove_with_proxy(hr, old_proxy_set);
5892       free_region(hr, pre_used, free_list, par);
5893     }
5894   } else {
5895     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5896   }
5897 }
5898 
5899 void G1CollectedHeap::free_region(HeapRegion* hr,
5900                                   size_t* pre_used,
5901                                   FreeRegionList* free_list,
5902                                   bool par) {
5903   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5904   assert(!hr->is_empty(), "the region should not be empty");
5905   assert(free_list != NULL, "pre-condition");
5906 
5907   // Clear the card counts for this region.
5908   // Note: we only need to do this if the region is not young
5909   // (since we don't refine cards in young regions).
5910   if (!hr->is_young()) {
5911     _cg1r->hot_card_cache()->reset_card_counts(hr);
5912   }
5913   *pre_used += hr->used();
5914   hr->hr_clear(par, true /* clear_space */);
5915   free_list->add_as_head(hr);
5916 }
5917 
5918 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5919                                      size_t* pre_used,
5920                                      FreeRegionList* free_list,
5921                                      HumongousRegionSet* humongous_proxy_set,
5922                                      bool par) {
5923   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5924   assert(free_list != NULL, "pre-condition");
5925   assert(humongous_proxy_set != NULL, "pre-condition");
5926 
5927   size_t hr_used = hr->used();
5928   size_t hr_capacity = hr->capacity();
5929   size_t hr_pre_used = 0;
5930   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5931   // We need to read this before we make the region non-humongous,
5932   // otherwise the information will be gone.
5933   uint last_index = hr->last_hc_index();
5934   hr->set_notHumongous();
5935   free_region(hr, &hr_pre_used, free_list, par);
5936 
5937   uint i = hr->hrs_index() + 1;
5938   while (i < last_index) {
5939     HeapRegion* curr_hr = region_at(i);
5940     assert(curr_hr->continuesHumongous(), "invariant");
5941     curr_hr->set_notHumongous();
5942     free_region(curr_hr, &hr_pre_used, free_list, par);
5943     i += 1;
5944   }
5945   assert(hr_pre_used == hr_used,
5946          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5947                  "should be the same", hr_pre_used, hr_used));
5948   *pre_used += hr_pre_used;
5949 }
5950 
5951 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5952                                        FreeRegionList* free_list,
5953                                        OldRegionSet* old_proxy_set,
5954                                        HumongousRegionSet* humongous_proxy_set,
5955                                        bool par) {
5956   if (pre_used > 0) {
5957     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5958     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5959     assert(_summary_bytes_used >= pre_used,
5960            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5961                    "should be >= pre_used: "SIZE_FORMAT,
5962                    _summary_bytes_used, pre_used));
5963     _summary_bytes_used -= pre_used;
5964   }
5965   if (free_list != NULL && !free_list->is_empty()) {
5966     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5967     _free_list.add_as_head(free_list);
5968   }
5969   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5970     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5971     _old_set.update_from_proxy(old_proxy_set);
5972   }
5973   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5974     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5975     _humongous_set.update_from_proxy(humongous_proxy_set);
5976   }
5977 }
5978 
5979 class G1ParCleanupCTTask : public AbstractGangTask {
5980   G1SATBCardTableModRefBS* _ct_bs;
5981   G1CollectedHeap* _g1h;
5982   HeapRegion* volatile _su_head;
5983 public:
5984   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5985                      G1CollectedHeap* g1h) :
5986     AbstractGangTask("G1 Par Cleanup CT Task"),
5987     _ct_bs(ct_bs), _g1h(g1h) { }
5988 
5989   void work(uint worker_id) {
5990     HeapRegion* r;
5991     while (r = _g1h->pop_dirty_cards_region()) {
5992       clear_cards(r);
5993     }
5994   }
5995 
5996   void clear_cards(HeapRegion* r) {
5997     // Cards of the survivors should have already been dirtied.
5998     if (!r->is_survivor()) {
5999       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6000     }
6001   }
6002 };
6003 
6004 #ifndef PRODUCT
6005 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6006   G1CollectedHeap* _g1h;
6007   G1SATBCardTableModRefBS* _ct_bs;
6008 public:
6009   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6010     : _g1h(g1h), _ct_bs(ct_bs) { }
6011   virtual bool doHeapRegion(HeapRegion* r) {
6012     if (r->is_survivor()) {
6013       _g1h->verify_dirty_region(r);
6014     } else {
6015       _g1h->verify_not_dirty_region(r);
6016     }
6017     return false;
6018   }
6019 };
6020 
6021 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6022   // All of the region should be clean.
6023   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6024   MemRegion mr(hr->bottom(), hr->end());
6025   ct_bs->verify_not_dirty_region(mr);
6026 }
6027 
6028 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6029   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
6030   // dirty allocated blocks as they allocate them. The thread that
6031   // retires each region and replaces it with a new one will do a
6032   // maximal allocation to fill in [pre_dummy_top(),end()] but will
6033   // not dirty that area (one less thing to have to do while holding
6034   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6035   // is dirty.
6036   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6037   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6038   if (hr->is_young()) {
6039     ct_bs->verify_g1_young_region(mr);
6040   } else {
6041     ct_bs->verify_dirty_region(mr);
6042   }
6043 }
6044 
6045 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6046   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6047   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6048     verify_dirty_region(hr);
6049   }
6050 }
6051 
6052 void G1CollectedHeap::verify_dirty_young_regions() {
6053   verify_dirty_young_list(_young_list->first_region());
6054 }
6055 #endif
6056 
6057 void G1CollectedHeap::cleanUpCardTable() {
6058   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6059   double start = os::elapsedTime();
6060 
6061   {
6062     // Iterate over the dirty cards region list.
6063     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6064 
6065     if (G1CollectedHeap::use_parallel_gc_threads()) {
6066       set_par_threads();
6067       workers()->run_task(&cleanup_task);
6068       set_par_threads(0);
6069     } else {
6070       while (_dirty_cards_region_list) {
6071         HeapRegion* r = _dirty_cards_region_list;
6072         cleanup_task.clear_cards(r);
6073         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6074         if (_dirty_cards_region_list == r) {
6075           // The last region.
6076           _dirty_cards_region_list = NULL;
6077         }
6078         r->set_next_dirty_cards_region(NULL);
6079       }
6080     }
6081 #ifndef PRODUCT
6082     if (G1VerifyCTCleanup || VerifyAfterGC) {
6083       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6084       heap_region_iterate(&cleanup_verifier);
6085     }
6086 #endif
6087   }
6088 
6089   double elapsed = os::elapsedTime() - start;
6090   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6091 }
6092 
6093 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6094   size_t pre_used = 0;
6095   FreeRegionList local_free_list("Local List for CSet Freeing");
6096 
6097   double young_time_ms     = 0.0;
6098   double non_young_time_ms = 0.0;
6099 
6100   // Since the collection set is a superset of the the young list,
6101   // all we need to do to clear the young list is clear its
6102   // head and length, and unlink any young regions in the code below
6103   _young_list->clear();
6104 
6105   G1CollectorPolicy* policy = g1_policy();
6106 
6107   double start_sec = os::elapsedTime();
6108   bool non_young = true;
6109 
6110   HeapRegion* cur = cs_head;
6111   int age_bound = -1;
6112   size_t rs_lengths = 0;
6113 
6114   while (cur != NULL) {
6115     assert(!is_on_master_free_list(cur), "sanity");
6116     if (non_young) {
6117       if (cur->is_young()) {
6118         double end_sec = os::elapsedTime();
6119         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6120         non_young_time_ms += elapsed_ms;
6121 
6122         start_sec = os::elapsedTime();
6123         non_young = false;
6124       }
6125     } else {
6126       if (!cur->is_young()) {
6127         double end_sec = os::elapsedTime();
6128         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6129         young_time_ms += elapsed_ms;
6130 
6131         start_sec = os::elapsedTime();
6132         non_young = true;
6133       }
6134     }
6135 
6136     rs_lengths += cur->rem_set()->occupied();
6137 
6138     HeapRegion* next = cur->next_in_collection_set();
6139     assert(cur->in_collection_set(), "bad CS");
6140     cur->set_next_in_collection_set(NULL);
6141     cur->set_in_collection_set(false);
6142 
6143     if (cur->is_young()) {
6144       int index = cur->young_index_in_cset();
6145       assert(index != -1, "invariant");
6146       assert((uint) index < policy->young_cset_region_length(), "invariant");
6147       size_t words_survived = _surviving_young_words[index];
6148       cur->record_surv_words_in_group(words_survived);
6149 
6150       // At this point the we have 'popped' cur from the collection set
6151       // (linked via next_in_collection_set()) but it is still in the
6152       // young list (linked via next_young_region()). Clear the
6153       // _next_young_region field.
6154       cur->set_next_young_region(NULL);
6155     } else {
6156       int index = cur->young_index_in_cset();
6157       assert(index == -1, "invariant");
6158     }
6159 
6160     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6161             (!cur->is_young() && cur->young_index_in_cset() == -1),
6162             "invariant" );
6163 
6164     if (!cur->evacuation_failed()) {
6165       MemRegion used_mr = cur->used_region();
6166 
6167       // And the region is empty.
6168       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6169       free_region(cur, &pre_used, &local_free_list, false /* par */);
6170     } else {
6171       cur->uninstall_surv_rate_group();
6172       if (cur->is_young()) {
6173         cur->set_young_index_in_cset(-1);
6174       }
6175       cur->set_not_young();
6176       cur->set_evacuation_failed(false);
6177       // The region is now considered to be old.
6178       _old_set.add(cur);
6179       evacuation_info.increment_collectionset_used_after(cur->used());
6180     }
6181     cur = next;
6182   }
6183 
6184   evacuation_info.set_regions_freed(local_free_list.length());
6185   policy->record_max_rs_lengths(rs_lengths);
6186   policy->cset_regions_freed();
6187 
6188   double end_sec = os::elapsedTime();
6189   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6190 
6191   if (non_young) {
6192     non_young_time_ms += elapsed_ms;
6193   } else {
6194     young_time_ms += elapsed_ms;
6195   }
6196 
6197   update_sets_after_freeing_regions(pre_used, &local_free_list,
6198                                     NULL /* old_proxy_set */,
6199                                     NULL /* humongous_proxy_set */,
6200                                     false /* par */);
6201   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6202   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6203 }
6204 
6205 // This routine is similar to the above but does not record
6206 // any policy statistics or update free lists; we are abandoning
6207 // the current incremental collection set in preparation of a
6208 // full collection. After the full GC we will start to build up
6209 // the incremental collection set again.
6210 // This is only called when we're doing a full collection
6211 // and is immediately followed by the tearing down of the young list.
6212 
6213 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6214   HeapRegion* cur = cs_head;
6215 
6216   while (cur != NULL) {
6217     HeapRegion* next = cur->next_in_collection_set();
6218     assert(cur->in_collection_set(), "bad CS");
6219     cur->set_next_in_collection_set(NULL);
6220     cur->set_in_collection_set(false);
6221     cur->set_young_index_in_cset(-1);
6222     cur = next;
6223   }
6224 }
6225 
6226 void G1CollectedHeap::set_free_regions_coming() {
6227   if (G1ConcRegionFreeingVerbose) {
6228     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6229                            "setting free regions coming");
6230   }
6231 
6232   assert(!free_regions_coming(), "pre-condition");
6233   _free_regions_coming = true;
6234 }
6235 
6236 void G1CollectedHeap::reset_free_regions_coming() {
6237   assert(free_regions_coming(), "pre-condition");
6238 
6239   {
6240     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6241     _free_regions_coming = false;
6242     SecondaryFreeList_lock->notify_all();
6243   }
6244 
6245   if (G1ConcRegionFreeingVerbose) {
6246     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6247                            "reset free regions coming");
6248   }
6249 }
6250 
6251 void G1CollectedHeap::wait_while_free_regions_coming() {
6252   // Most of the time we won't have to wait, so let's do a quick test
6253   // first before we take the lock.
6254   if (!free_regions_coming()) {
6255     return;
6256   }
6257 
6258   if (G1ConcRegionFreeingVerbose) {
6259     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6260                            "waiting for free regions");
6261   }
6262 
6263   {
6264     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6265     while (free_regions_coming()) {
6266       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6267     }
6268   }
6269 
6270   if (G1ConcRegionFreeingVerbose) {
6271     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6272                            "done waiting for free regions");
6273   }
6274 }
6275 
6276 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6277   assert(heap_lock_held_for_gc(),
6278               "the heap lock should already be held by or for this thread");
6279   _young_list->push_region(hr);
6280 }
6281 
6282 class NoYoungRegionsClosure: public HeapRegionClosure {
6283 private:
6284   bool _success;
6285 public:
6286   NoYoungRegionsClosure() : _success(true) { }
6287   bool doHeapRegion(HeapRegion* r) {
6288     if (r->is_young()) {
6289       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6290                              r->bottom(), r->end());
6291       _success = false;
6292     }
6293     return false;
6294   }
6295   bool success() { return _success; }
6296 };
6297 
6298 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6299   bool ret = _young_list->check_list_empty(check_sample);
6300 
6301   if (check_heap) {
6302     NoYoungRegionsClosure closure;
6303     heap_region_iterate(&closure);
6304     ret = ret && closure.success();
6305   }
6306 
6307   return ret;
6308 }
6309 
6310 class TearDownRegionSetsClosure : public HeapRegionClosure {
6311 private:
6312   OldRegionSet *_old_set;
6313 
6314 public:
6315   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6316 
6317   bool doHeapRegion(HeapRegion* r) {
6318     if (r->is_empty()) {
6319       // We ignore empty regions, we'll empty the free list afterwards
6320     } else if (r->is_young()) {
6321       // We ignore young regions, we'll empty the young list afterwards
6322     } else if (r->isHumongous()) {
6323       // We ignore humongous regions, we're not tearing down the
6324       // humongous region set
6325     } else {
6326       // The rest should be old
6327       _old_set->remove(r);
6328     }
6329     return false;
6330   }
6331 
6332   ~TearDownRegionSetsClosure() {
6333     assert(_old_set->is_empty(), "post-condition");
6334   }
6335 };
6336 
6337 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6338   assert_at_safepoint(true /* should_be_vm_thread */);
6339 
6340   if (!free_list_only) {
6341     TearDownRegionSetsClosure cl(&_old_set);
6342     heap_region_iterate(&cl);
6343 
6344     // Need to do this after the heap iteration to be able to
6345     // recognize the young regions and ignore them during the iteration.
6346     _young_list->empty_list();
6347   }
6348   _free_list.remove_all();
6349 }
6350 
6351 class RebuildRegionSetsClosure : public HeapRegionClosure {
6352 private:
6353   bool            _free_list_only;
6354   OldRegionSet*   _old_set;
6355   FreeRegionList* _free_list;
6356   size_t          _total_used;
6357 
6358 public:
6359   RebuildRegionSetsClosure(bool free_list_only,
6360                            OldRegionSet* old_set, FreeRegionList* free_list) :
6361     _free_list_only(free_list_only),
6362     _old_set(old_set), _free_list(free_list), _total_used(0) {
6363     assert(_free_list->is_empty(), "pre-condition");
6364     if (!free_list_only) {
6365       assert(_old_set->is_empty(), "pre-condition");
6366     }
6367   }
6368 
6369   bool doHeapRegion(HeapRegion* r) {
6370     if (r->continuesHumongous()) {
6371       return false;
6372     }
6373 
6374     if (r->is_empty()) {
6375       // Add free regions to the free list
6376       _free_list->add_as_tail(r);
6377     } else if (!_free_list_only) {
6378       assert(!r->is_young(), "we should not come across young regions");
6379 
6380       if (r->isHumongous()) {
6381         // We ignore humongous regions, we left the humongous set unchanged
6382       } else {
6383         // The rest should be old, add them to the old set
6384         _old_set->add(r);
6385       }
6386       _total_used += r->used();
6387     }
6388 
6389     return false;
6390   }
6391 
6392   size_t total_used() {
6393     return _total_used;
6394   }
6395 };
6396 
6397 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6398   assert_at_safepoint(true /* should_be_vm_thread */);
6399 
6400   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6401   heap_region_iterate(&cl);
6402 
6403   if (!free_list_only) {
6404     _summary_bytes_used = cl.total_used();
6405   }
6406   assert(_summary_bytes_used == recalculate_used(),
6407          err_msg("inconsistent _summary_bytes_used, "
6408                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6409                  _summary_bytes_used, recalculate_used()));
6410 }
6411 
6412 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6413   _refine_cte_cl->set_concurrent(concurrent);
6414 }
6415 
6416 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6417   HeapRegion* hr = heap_region_containing(p);
6418   if (hr == NULL) {
6419     return false;
6420   } else {
6421     return hr->is_in(p);
6422   }
6423 }
6424 
6425 // Methods for the mutator alloc region
6426 
6427 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6428                                                       bool force) {
6429   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6430   assert(!force || g1_policy()->can_expand_young_list(),
6431          "if force is true we should be able to expand the young list");
6432   bool young_list_full = g1_policy()->is_young_list_full();
6433   if (force || !young_list_full) {
6434     HeapRegion* new_alloc_region = new_region(word_size,
6435                                               false /* do_expand */);
6436     if (new_alloc_region != NULL) {
6437       set_region_short_lived_locked(new_alloc_region);
6438       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6439       return new_alloc_region;
6440     }
6441   }
6442   return NULL;
6443 }
6444 
6445 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6446                                                   size_t allocated_bytes) {
6447   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6448   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6449 
6450   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6451   _summary_bytes_used += allocated_bytes;
6452   _hr_printer.retire(alloc_region);
6453   // We update the eden sizes here, when the region is retired,
6454   // instead of when it's allocated, since this is the point that its
6455   // used space has been recored in _summary_bytes_used.
6456   g1mm()->update_eden_size();
6457 }
6458 
6459 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6460                                                     bool force) {
6461   return _g1h->new_mutator_alloc_region(word_size, force);
6462 }
6463 
6464 void G1CollectedHeap::set_par_threads() {
6465   // Don't change the number of workers.  Use the value previously set
6466   // in the workgroup.
6467   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6468   uint n_workers = workers()->active_workers();
6469   assert(UseDynamicNumberOfGCThreads ||
6470            n_workers == workers()->total_workers(),
6471       "Otherwise should be using the total number of workers");
6472   if (n_workers == 0) {
6473     assert(false, "Should have been set in prior evacuation pause.");
6474     n_workers = ParallelGCThreads;
6475     workers()->set_active_workers(n_workers);
6476   }
6477   set_par_threads(n_workers);
6478 }
6479 
6480 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6481                                        size_t allocated_bytes) {
6482   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6483 }
6484 
6485 // Methods for the GC alloc regions
6486 
6487 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6488                                                  uint count,
6489                                                  GCAllocPurpose ap) {
6490   assert(FreeList_lock->owned_by_self(), "pre-condition");
6491 
6492   if (count < g1_policy()->max_regions(ap)) {
6493     HeapRegion* new_alloc_region = new_region(word_size,
6494                                               true /* do_expand */);
6495     if (new_alloc_region != NULL) {
6496       // We really only need to do this for old regions given that we
6497       // should never scan survivors. But it doesn't hurt to do it
6498       // for survivors too.
6499       new_alloc_region->set_saved_mark();
6500       if (ap == GCAllocForSurvived) {
6501         new_alloc_region->set_survivor();
6502         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6503       } else {
6504         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6505       }
6506       bool during_im = g1_policy()->during_initial_mark_pause();
6507       new_alloc_region->note_start_of_copying(during_im);
6508       return new_alloc_region;
6509     } else {
6510       g1_policy()->note_alloc_region_limit_reached(ap);
6511     }
6512   }
6513   return NULL;
6514 }
6515 
6516 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6517                                              size_t allocated_bytes,
6518                                              GCAllocPurpose ap) {
6519   bool during_im = g1_policy()->during_initial_mark_pause();
6520   alloc_region->note_end_of_copying(during_im);
6521   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6522   if (ap == GCAllocForSurvived) {
6523     young_list()->add_survivor_region(alloc_region);
6524   } else {
6525     _old_set.add(alloc_region);
6526   }
6527   _hr_printer.retire(alloc_region);
6528 }
6529 
6530 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6531                                                        bool force) {
6532   assert(!force, "not supported for GC alloc regions");
6533   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6534 }
6535 
6536 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6537                                           size_t allocated_bytes) {
6538   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6539                                GCAllocForSurvived);
6540 }
6541 
6542 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6543                                                   bool force) {
6544   assert(!force, "not supported for GC alloc regions");
6545   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6546 }
6547 
6548 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6549                                      size_t allocated_bytes) {
6550   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6551                                GCAllocForTenured);
6552 }
6553 // Heap region set verification
6554 
6555 class VerifyRegionListsClosure : public HeapRegionClosure {
6556 private:
6557   FreeRegionList*     _free_list;
6558   OldRegionSet*       _old_set;
6559   HumongousRegionSet* _humongous_set;
6560   uint                _region_count;
6561 
6562 public:
6563   VerifyRegionListsClosure(OldRegionSet* old_set,
6564                            HumongousRegionSet* humongous_set,
6565                            FreeRegionList* free_list) :
6566     _old_set(old_set), _humongous_set(humongous_set),
6567     _free_list(free_list), _region_count(0) { }
6568 
6569   uint region_count() { return _region_count; }
6570 
6571   bool doHeapRegion(HeapRegion* hr) {
6572     _region_count += 1;
6573 
6574     if (hr->continuesHumongous()) {
6575       return false;
6576     }
6577 
6578     if (hr->is_young()) {
6579       // TODO
6580     } else if (hr->startsHumongous()) {
6581       _humongous_set->verify_next_region(hr);
6582     } else if (hr->is_empty()) {
6583       _free_list->verify_next_region(hr);
6584     } else {
6585       _old_set->verify_next_region(hr);
6586     }
6587     return false;
6588   }
6589 };
6590 
6591 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6592                                              HeapWord* bottom) {
6593   HeapWord* end = bottom + HeapRegion::GrainWords;
6594   MemRegion mr(bottom, end);
6595   assert(_g1_reserved.contains(mr), "invariant");
6596   // This might return NULL if the allocation fails
6597   return new HeapRegion(hrs_index, _bot_shared, mr);
6598 }
6599 
6600 void G1CollectedHeap::verify_region_sets() {
6601   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6602 
6603   // First, check the explicit lists.
6604   _free_list.verify();
6605   {
6606     // Given that a concurrent operation might be adding regions to
6607     // the secondary free list we have to take the lock before
6608     // verifying it.
6609     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6610     _secondary_free_list.verify();
6611   }
6612   _old_set.verify();
6613   _humongous_set.verify();
6614 
6615   // If a concurrent region freeing operation is in progress it will
6616   // be difficult to correctly attributed any free regions we come
6617   // across to the correct free list given that they might belong to
6618   // one of several (free_list, secondary_free_list, any local lists,
6619   // etc.). So, if that's the case we will skip the rest of the
6620   // verification operation. Alternatively, waiting for the concurrent
6621   // operation to complete will have a non-trivial effect on the GC's
6622   // operation (no concurrent operation will last longer than the
6623   // interval between two calls to verification) and it might hide
6624   // any issues that we would like to catch during testing.
6625   if (free_regions_coming()) {
6626     return;
6627   }
6628 
6629   // Make sure we append the secondary_free_list on the free_list so
6630   // that all free regions we will come across can be safely
6631   // attributed to the free_list.
6632   append_secondary_free_list_if_not_empty_with_lock();
6633 
6634   // Finally, make sure that the region accounting in the lists is
6635   // consistent with what we see in the heap.
6636   _old_set.verify_start();
6637   _humongous_set.verify_start();
6638   _free_list.verify_start();
6639 
6640   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6641   heap_region_iterate(&cl);
6642 
6643   _old_set.verify_end();
6644   _humongous_set.verify_end();
6645   _free_list.verify_end();
6646 }
6647 
6648 // Optimized nmethod scanning
6649 
6650 class RegisterNMethodOopClosure: public OopClosure {
6651   G1CollectedHeap* _g1h;
6652   nmethod* _nm;
6653 
6654   template <class T> void do_oop_work(T* p) {
6655     T heap_oop = oopDesc::load_heap_oop(p);
6656     if (!oopDesc::is_null(heap_oop)) {
6657       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6658       HeapRegion* hr = _g1h->heap_region_containing(obj);
6659       assert(!hr->continuesHumongous(), "code root in continuation of humongous region?");
6660 
6661       // HeapRegion::add_strong_code_root() avoids adding duplicate
6662       // entries but having duplicates is  OK since we "mark" nmethods
6663       // as visited when we scan the strong code root lists during the GC.
6664       hr->add_strong_code_root(_nm);
6665       assert(hr->rem_set()->strong_code_roots_list_contains(_nm), "add failed?");
6666     }
6667   }
6668 
6669 public:
6670   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6671     _g1h(g1h), _nm(nm) {}
6672 
6673   void do_oop(oop* p)       { do_oop_work(p); }
6674   void do_oop(narrowOop* p) { do_oop_work(p); }
6675 };
6676 
6677 class UnregisterNMethodOopClosure: public OopClosure {
6678   G1CollectedHeap* _g1h;
6679   nmethod* _nm;
6680 
6681   template <class T> void do_oop_work(T* p) {
6682     T heap_oop = oopDesc::load_heap_oop(p);
6683     if (!oopDesc::is_null(heap_oop)) {
6684       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6685       HeapRegion* hr = _g1h->heap_region_containing(obj);
6686       assert(!hr->continuesHumongous(), "code root in continuation of humongous region?");
6687       hr->remove_strong_code_root(_nm);
6688       assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), "remove failed?");
6689     }
6690   }
6691 
6692 public:
6693   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6694     _g1h(g1h), _nm(nm) {}
6695 
6696   void do_oop(oop* p)       { do_oop_work(p); }
6697   void do_oop(narrowOop* p) { do_oop_work(p); }
6698 };
6699 
6700 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6701   CollectedHeap::register_nmethod(nm);
6702 
6703   guarantee(nm != NULL, "sanity");
6704   RegisterNMethodOopClosure reg_cl(this, nm);
6705   nm->oops_do(&reg_cl);
6706 }
6707 
6708 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6709   CollectedHeap::unregister_nmethod(nm);
6710 
6711   guarantee(nm != NULL, "sanity");
6712   UnregisterNMethodOopClosure reg_cl(this, nm);
6713   nm->oops_do(&reg_cl, true);
6714 }
6715 
6716 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6717 public:
6718   bool doHeapRegion(HeapRegion *hr) {
6719     assert(!hr->isHumongous(), "humongous region in collection set?");
6720     hr->migrate_strong_code_roots();
6721     return false;
6722   }
6723 };
6724 
6725 void G1CollectedHeap::migrate_strong_code_roots() {
6726   MigrateCodeRootsHeapRegionClosure cl;
6727   double migrate_start = os::elapsedTime();
6728   collection_set_iterate(&cl);
6729   double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6730   g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6731 }
6732 
6733 // Mark all the code roots that point into regions *not* in the
6734 // collection set.
6735 //
6736 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6737 // walking the the code roots lists of regions not in the collection
6738 // set. Suppose we have an nmethod (M) that points to objects in two
6739 // separate regions - one in the collection set (R1) and one not (R2).
6740 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6741 // nmethod M when walking the code roots for R1. When we come to scan
6742 // the code roots for R2, we would see that M is already marked and it
6743 // would be skipped and the objects in R2 that are referenced from M
6744 // would not be evacuated.
6745 
6746 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6747 
6748   class MarkStrongCodeRootOopClosure: public OopClosure {
6749     ConcurrentMark* _cm;
6750     HeapRegion* _hr;
6751     uint _worker_id;
6752 
6753     template <class T> void do_oop_work(T* p) {
6754       T heap_oop = oopDesc::load_heap_oop(p);
6755       if (!oopDesc::is_null(heap_oop)) {
6756         oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6757         // Only mark objects in the region (which is assumed
6758         // to be not in the collection set).
6759         if (_hr->is_in(obj)) {
6760           _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6761         }
6762       }
6763     }
6764 
6765   public:
6766     MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6767       _cm(cm), _hr(hr), _worker_id(worker_id) {
6768       assert(!_hr->in_collection_set(), "sanity");
6769     }
6770 
6771     void do_oop(narrowOop* p) { do_oop_work(p); }
6772     void do_oop(oop* p)       { do_oop_work(p); }
6773   };
6774 
6775   MarkStrongCodeRootOopClosure _oop_cl;
6776 
6777 public:
6778   MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6779     _oop_cl(cm, hr, worker_id) {}
6780 
6781   void do_code_blob(CodeBlob* cb) {
6782     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6783     if (nm != NULL) {
6784       nm->oops_do(&_oop_cl);
6785     }
6786   }
6787 };
6788 
6789 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6790   G1CollectedHeap* _g1h;
6791   uint _worker_id;
6792 
6793 public:
6794   MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6795     _g1h(g1h), _worker_id(worker_id) {}
6796 
6797   bool doHeapRegion(HeapRegion *hr) {
6798     HeapRegionRemSet* hrrs = hr->rem_set();
6799     if (hr->continuesHumongous()) {
6800       // Code roots should never be attached to a continuation of a humongous region
6801       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
6802       return false;
6803     }
6804 
6805     if (hr->in_collection_set()) {
6806       // Don't mark code roots into regions in the collection set here.
6807       // They will be marked when we scan them.
6808       return false;
6809     }
6810 
6811     MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6812     hr->strong_code_roots_do(&cb_cl);
6813     return false;
6814   }
6815 };
6816 
6817 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6818   MarkStrongCodeRootsHRClosure cl(this, worker_id);
6819   if (G1CollectedHeap::use_parallel_gc_threads()) {
6820     heap_region_par_iterate_chunked(&cl,
6821                                     worker_id,
6822                                     workers()->active_workers(),
6823                                     HeapRegion::ParMarkRootClaimValue);
6824   } else {
6825     heap_region_iterate(&cl);
6826   }
6827 }
6828 
6829 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6830   G1CollectedHeap* _g1h;
6831 
6832 public:
6833   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6834     _g1h(g1h) {}
6835 
6836   void do_code_blob(CodeBlob* cb) {
6837     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6838     if (nm == NULL) {
6839       return;
6840     }
6841 
6842     if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6843       _g1h->register_nmethod(nm);
6844     }
6845   }
6846 };
6847 
6848 void G1CollectedHeap::rebuild_strong_code_roots() {
6849   RebuildStrongCodeRootClosure blob_cl(this);
6850   CodeCache::blobs_do(&blob_cl);
6851 }
--- EOF ---