1 /*
   2  * Copyright (c) 2001, 2014, 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 #if !defined(__clang_major__) && defined(__GNUC__)
  26 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess.
  27 #endif
  28 
  29 #include "precompiled.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/icBuffer.hpp"
  32 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  33 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  34 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  35 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  36 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  37 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  38 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  39 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  40 #include "gc_implementation/g1/g1EvacFailure.hpp"
  41 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  42 #include "gc_implementation/g1/g1Log.hpp"
  43 #include "gc_implementation/g1/g1MarkSweep.hpp"
  44 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  45 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
  46 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
  47 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  48 #include "gc_implementation/g1/g1StringDedup.hpp"
  49 #include "gc_implementation/g1/g1YCTypes.hpp"
  50 #include "gc_implementation/g1/heapRegion.inline.hpp"
  51 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  52 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
  53 #include "gc_implementation/g1/vm_operations_g1.hpp"
  54 #include "gc_implementation/shared/gcHeapSummary.hpp"
  55 #include "gc_implementation/shared/gcTimer.hpp"
  56 #include "gc_implementation/shared/gcTrace.hpp"
  57 #include "gc_implementation/shared/gcTraceTime.hpp"
  58 #include "gc_implementation/shared/isGCActiveMark.hpp"
  59 #include "memory/allocation.hpp"
  60 #include "memory/gcLocker.inline.hpp"
  61 #include "memory/generationSpec.hpp"
  62 #include "memory/iterator.hpp"
  63 #include "memory/referenceProcessor.hpp"
  64 #include "oops/oop.inline.hpp"
  65 #include "oops/oop.pcgc.inline.hpp"
  66 #include "runtime/orderAccess.inline.hpp"
  67 #include "runtime/vmThread.hpp"
  68 
  69 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  70 
  71 // turn it on so that the contents of the young list (scan-only /
  72 // to-be-collected) are printed at "strategic" points before / during
  73 // / after the collection --- this is useful for debugging
  74 #define YOUNG_LIST_VERBOSE 0
  75 // CURRENT STATUS
  76 // This file is under construction.  Search for "FIXME".
  77 
  78 // INVARIANTS/NOTES
  79 //
  80 // All allocation activity covered by the G1CollectedHeap interface is
  81 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  82 // and allocate_new_tlab, which are the "entry" points to the
  83 // allocation code from the rest of the JVM.  (Note that this does not
  84 // apply to TLAB allocation, which is not part of this interface: it
  85 // is done by clients of this interface.)
  86 
  87 // Notes on implementation of parallelism in different tasks.
  88 //
  89 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  90 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  91 // It does use run_task() which sets _n_workers in the task.
  92 // G1ParTask executes g1_process_roots() ->
  93 // SharedHeap::process_roots() which calls eventually to
  94 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  95 // SequentialSubTasksDone.  SharedHeap::process_roots() also
  96 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  97 //
  98 
  99 // Local to this file.
 100 
 101 class RefineCardTableEntryClosure: public CardTableEntryClosure {
 102   bool _concurrent;
 103 public:
 104   RefineCardTableEntryClosure() : _concurrent(true) { }
 105 
 106   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 107     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 108     // This path is executed by the concurrent refine or mutator threads,
 109     // concurrently, and so we do not care if card_ptr contains references
 110     // that point into the collection set.
 111     assert(!oops_into_cset, "should be");
 112 
 113     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 114       // Caller will actually yield.
 115       return false;
 116     }
 117     // Otherwise, we finished successfully; return true.
 118     return true;
 119   }
 120 
 121   void set_concurrent(bool b) { _concurrent = b; }
 122 };
 123 
 124 
 125 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 126   size_t _num_processed;
 127   CardTableModRefBS* _ctbs;
 128   int _histo[256];
 129 
 130  public:
 131   ClearLoggedCardTableEntryClosure() :
 132     _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
 133   {
 134     for (int i = 0; i < 256; i++) _histo[i] = 0;
 135   }
 136 
 137   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 138     unsigned char* ujb = (unsigned char*)card_ptr;
 139     int ind = (int)(*ujb);
 140     _histo[ind]++;
 141 
 142     *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
 143     _num_processed++;
 144 
 145     return true;
 146   }
 147 
 148   size_t num_processed() { return _num_processed; }
 149 
 150   void print_histo() {
 151     gclog_or_tty->print_cr("Card table value histogram:");
 152     for (int i = 0; i < 256; i++) {
 153       if (_histo[i] != 0) {
 154         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 155       }
 156     }
 157   }
 158 };
 159 
 160 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 161  private:
 162   size_t _num_processed;
 163 
 164  public:
 165   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 166 
 167   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 168     *card_ptr = CardTableModRefBS::dirty_card_val();
 169     _num_processed++;
 170     return true;
 171   }
 172 
 173   size_t num_processed() const { return _num_processed; }
 174 };
 175 
 176 YoungList::YoungList(G1CollectedHeap* g1h) :
 177     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 178     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 179   guarantee(check_list_empty(false), "just making sure...");
 180 }
 181 
 182 void YoungList::push_region(HeapRegion *hr) {
 183   assert(!hr->is_young(), "should not already be young");
 184   assert(hr->get_next_young_region() == NULL, "cause it should!");
 185 
 186   hr->set_next_young_region(_head);
 187   _head = hr;
 188 
 189   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 190   ++_length;
 191 }
 192 
 193 void YoungList::add_survivor_region(HeapRegion* hr) {
 194   assert(hr->is_survivor(), "should be flagged as survivor region");
 195   assert(hr->get_next_young_region() == NULL, "cause it should!");
 196 
 197   hr->set_next_young_region(_survivor_head);
 198   if (_survivor_head == NULL) {
 199     _survivor_tail = hr;
 200   }
 201   _survivor_head = hr;
 202   ++_survivor_length;
 203 }
 204 
 205 void YoungList::empty_list(HeapRegion* list) {
 206   while (list != NULL) {
 207     HeapRegion* next = list->get_next_young_region();
 208     list->set_next_young_region(NULL);
 209     list->uninstall_surv_rate_group();
 210     list->set_not_young();
 211     list = next;
 212   }
 213 }
 214 
 215 void YoungList::empty_list() {
 216   assert(check_list_well_formed(), "young list should be well formed");
 217 
 218   empty_list(_head);
 219   _head = NULL;
 220   _length = 0;
 221 
 222   empty_list(_survivor_head);
 223   _survivor_head = NULL;
 224   _survivor_tail = NULL;
 225   _survivor_length = 0;
 226 
 227   _last_sampled_rs_lengths = 0;
 228 
 229   assert(check_list_empty(false), "just making sure...");
 230 }
 231 
 232 bool YoungList::check_list_well_formed() {
 233   bool ret = true;
 234 
 235   uint length = 0;
 236   HeapRegion* curr = _head;
 237   HeapRegion* last = NULL;
 238   while (curr != NULL) {
 239     if (!curr->is_young()) {
 240       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 241                              "incorrectly tagged (y: %d, surv: %d)",
 242                              curr->bottom(), curr->end(),
 243                              curr->is_young(), curr->is_survivor());
 244       ret = false;
 245     }
 246     ++length;
 247     last = curr;
 248     curr = curr->get_next_young_region();
 249   }
 250   ret = ret && (length == _length);
 251 
 252   if (!ret) {
 253     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 254     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 255                            length, _length);
 256   }
 257 
 258   return ret;
 259 }
 260 
 261 bool YoungList::check_list_empty(bool check_sample) {
 262   bool ret = true;
 263 
 264   if (_length != 0) {
 265     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 266                   _length);
 267     ret = false;
 268   }
 269   if (check_sample && _last_sampled_rs_lengths != 0) {
 270     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 271     ret = false;
 272   }
 273   if (_head != NULL) {
 274     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 275     ret = false;
 276   }
 277   if (!ret) {
 278     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 279   }
 280 
 281   return ret;
 282 }
 283 
 284 void
 285 YoungList::rs_length_sampling_init() {
 286   _sampled_rs_lengths = 0;
 287   _curr               = _head;
 288 }
 289 
 290 bool
 291 YoungList::rs_length_sampling_more() {
 292   return _curr != NULL;
 293 }
 294 
 295 void
 296 YoungList::rs_length_sampling_next() {
 297   assert( _curr != NULL, "invariant" );
 298   size_t rs_length = _curr->rem_set()->occupied();
 299 
 300   _sampled_rs_lengths += rs_length;
 301 
 302   // The current region may not yet have been added to the
 303   // incremental collection set (it gets added when it is
 304   // retired as the current allocation region).
 305   if (_curr->in_collection_set()) {
 306     // Update the collection set policy information for this region
 307     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 308   }
 309 
 310   _curr = _curr->get_next_young_region();
 311   if (_curr == NULL) {
 312     _last_sampled_rs_lengths = _sampled_rs_lengths;
 313     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 314   }
 315 }
 316 
 317 void
 318 YoungList::reset_auxilary_lists() {
 319   guarantee( is_empty(), "young list should be empty" );
 320   assert(check_list_well_formed(), "young list should be well formed");
 321 
 322   // Add survivor regions to SurvRateGroup.
 323   _g1h->g1_policy()->note_start_adding_survivor_regions();
 324   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 325 
 326   int young_index_in_cset = 0;
 327   for (HeapRegion* curr = _survivor_head;
 328        curr != NULL;
 329        curr = curr->get_next_young_region()) {
 330     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 331 
 332     // The region is a non-empty survivor so let's add it to
 333     // the incremental collection set for the next evacuation
 334     // pause.
 335     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 336     young_index_in_cset += 1;
 337   }
 338   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 339   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 340 
 341   _head   = _survivor_head;
 342   _length = _survivor_length;
 343   if (_survivor_head != NULL) {
 344     assert(_survivor_tail != NULL, "cause it shouldn't be");
 345     assert(_survivor_length > 0, "invariant");
 346     _survivor_tail->set_next_young_region(NULL);
 347   }
 348 
 349   // Don't clear the survivor list handles until the start of
 350   // the next evacuation pause - we need it in order to re-tag
 351   // the survivor regions from this evacuation pause as 'young'
 352   // at the start of the next.
 353 
 354   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 355 
 356   assert(check_list_well_formed(), "young list should be well formed");
 357 }
 358 
 359 void YoungList::print() {
 360   HeapRegion* lists[] = {_head,   _survivor_head};
 361   const char* names[] = {"YOUNG", "SURVIVOR"};
 362 
 363   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 364     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 365     HeapRegion *curr = lists[list];
 366     if (curr == NULL)
 367       gclog_or_tty->print_cr("  empty");
 368     while (curr != NULL) {
 369       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 370                              HR_FORMAT_PARAMS(curr),
 371                              curr->prev_top_at_mark_start(),
 372                              curr->next_top_at_mark_start(),
 373                              curr->age_in_surv_rate_group_cond());
 374       curr = curr->get_next_young_region();
 375     }
 376   }
 377 
 378   gclog_or_tty->cr();
 379 }
 380 
 381 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 382   OtherRegionsTable::invalidate(start_idx, num_regions);
 383 }
 384 
 385 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
 386   reset_from_card_cache(start_idx, num_regions);
 387 }
 388 
 389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 390 {
 391   // Claim the right to put the region on the dirty cards region list
 392   // by installing a self pointer.
 393   HeapRegion* next = hr->get_next_dirty_cards_region();
 394   if (next == NULL) {
 395     HeapRegion* res = (HeapRegion*)
 396       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 397                           NULL);
 398     if (res == NULL) {
 399       HeapRegion* head;
 400       do {
 401         // Put the region to the dirty cards region list.
 402         head = _dirty_cards_region_list;
 403         next = (HeapRegion*)
 404           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 405         if (next == head) {
 406           assert(hr->get_next_dirty_cards_region() == hr,
 407                  "hr->get_next_dirty_cards_region() != hr");
 408           if (next == NULL) {
 409             // The last region in the list points to itself.
 410             hr->set_next_dirty_cards_region(hr);
 411           } else {
 412             hr->set_next_dirty_cards_region(next);
 413           }
 414         }
 415       } while (next != head);
 416     }
 417   }
 418 }
 419 
 420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 421 {
 422   HeapRegion* head;
 423   HeapRegion* hr;
 424   do {
 425     head = _dirty_cards_region_list;
 426     if (head == NULL) {
 427       return NULL;
 428     }
 429     HeapRegion* new_head = head->get_next_dirty_cards_region();
 430     if (head == new_head) {
 431       // The last region.
 432       new_head = NULL;
 433     }
 434     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 435                                           head);
 436   } while (hr != head);
 437   assert(hr != NULL, "invariant");
 438   hr->set_next_dirty_cards_region(NULL);
 439   return hr;
 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   if (p == NULL) {
 455     return false;
 456   }
 457   return heap_region_containing(p)->in_collection_set();
 458 }
 459 #endif
 460 
 461 // Returns true if the reference points to an object that
 462 // can move in an incremental collection.
 463 bool G1CollectedHeap::is_scavengable(const void* p) {
 464   HeapRegion* hr = heap_region_containing(p);
 465   return !hr->isHumongous();
 466 }
 467 
 468 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 469   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 470   CardTableModRefBS* ct_bs = g1_barrier_set();
 471 
 472   // Count the dirty cards at the start.
 473   CountNonCleanMemRegionClosure count1(this);
 474   ct_bs->mod_card_iterate(&count1);
 475   int orig_count = count1.n();
 476 
 477   // First clear the logged cards.
 478   ClearLoggedCardTableEntryClosure clear;
 479   dcqs.apply_closure_to_all_completed_buffers(&clear);
 480   dcqs.iterate_closure_all_threads(&clear, false);
 481   clear.print_histo();
 482 
 483   // Now ensure that there's no dirty cards.
 484   CountNonCleanMemRegionClosure count2(this);
 485   ct_bs->mod_card_iterate(&count2);
 486   if (count2.n() != 0) {
 487     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 488                            count2.n(), orig_count);
 489   }
 490   guarantee(count2.n() == 0, "Card table should be clean.");
 491 
 492   RedirtyLoggedCardTableEntryClosure redirty;
 493   dcqs.apply_closure_to_all_completed_buffers(&redirty);
 494   dcqs.iterate_closure_all_threads(&redirty, false);
 495   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 496                          clear.num_processed(), orig_count);
 497   guarantee(redirty.num_processed() == clear.num_processed(),
 498             err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
 499                     redirty.num_processed(), clear.num_processed()));
 500 
 501   CountNonCleanMemRegionClosure count3(this);
 502   ct_bs->mod_card_iterate(&count3);
 503   if (count3.n() != orig_count) {
 504     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 505                            orig_count, count3.n());
 506     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 507   }
 508 }
 509 
 510 // Private class members.
 511 
 512 G1CollectedHeap* G1CollectedHeap::_g1h;
 513 
 514 // Private methods.
 515 
 516 HeapRegion*
 517 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 518   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 519   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 520     if (!_secondary_free_list.is_empty()) {
 521       if (G1ConcRegionFreeingVerbose) {
 522         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 523                                "secondary_free_list has %u entries",
 524                                _secondary_free_list.length());
 525       }
 526       // It looks as if there are free regions available on the
 527       // secondary_free_list. Let's move them to the free_list and try
 528       // again to allocate from it.
 529       append_secondary_free_list();
 530 
 531       assert(_hrs.num_free_regions() > 0, "if the secondary_free_list was not "
 532              "empty we should have moved at least one entry to the free_list");
 533       HeapRegion* res = _hrs.allocate_free_region(is_old);
 534       if (G1ConcRegionFreeingVerbose) {
 535         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 536                                "allocated "HR_FORMAT" from secondary_free_list",
 537                                HR_FORMAT_PARAMS(res));
 538       }
 539       return res;
 540     }
 541 
 542     // Wait here until we get notified either when (a) there are no
 543     // more free regions coming or (b) some regions have been moved on
 544     // the secondary_free_list.
 545     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 546   }
 547 
 548   if (G1ConcRegionFreeingVerbose) {
 549     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 550                            "could not allocate from secondary_free_list");
 551   }
 552   return NULL;
 553 }
 554 
 555 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 556   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 557          "the only time we use this to allocate a humongous region is "
 558          "when we are allocating a single humongous region");
 559 
 560   HeapRegion* res;
 561   if (G1StressConcRegionFreeing) {
 562     if (!_secondary_free_list.is_empty()) {
 563       if (G1ConcRegionFreeingVerbose) {
 564         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 565                                "forced to look at the secondary_free_list");
 566       }
 567       res = new_region_try_secondary_free_list(is_old);
 568       if (res != NULL) {
 569         return res;
 570       }
 571     }
 572   }
 573 
 574   res = _hrs.allocate_free_region(is_old);
 575 
 576   if (res == NULL) {
 577     if (G1ConcRegionFreeingVerbose) {
 578       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 579                              "res == NULL, trying the secondary_free_list");
 580     }
 581     res = new_region_try_secondary_free_list(is_old);
 582   }
 583   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 584     // Currently, only attempts to allocate GC alloc regions set
 585     // do_expand to true. So, we should only reach here during a
 586     // safepoint. If this assumption changes we might have to
 587     // reconsider the use of _expand_heap_after_alloc_failure.
 588     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 589 
 590     ergo_verbose1(ErgoHeapSizing,
 591                   "attempt heap expansion",
 592                   ergo_format_reason("region allocation request failed")
 593                   ergo_format_byte("allocation request"),
 594                   word_size * HeapWordSize);
 595     if (expand(word_size * HeapWordSize)) {
 596       // Given that expand() succeeded in expanding the heap, and we
 597       // always expand the heap by an amount aligned to the heap
 598       // region size, the free list should in theory not be empty.
 599       // In either case allocate_free_region() will check for NULL.
 600       res = _hrs.allocate_free_region(is_old);
 601     } else {
 602       _expand_heap_after_alloc_failure = false;
 603     }
 604   }
 605   return res;
 606 }
 607 
 608 HeapWord*
 609 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 610                                                            uint num_regions,
 611                                                            size_t word_size) {
 612   assert(first != G1_NO_HRS_INDEX, "pre-condition");
 613   assert(isHumongous(word_size), "word_size should be humongous");
 614   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 615 
 616   // Index of last region in the series + 1.
 617   uint last = first + num_regions;
 618 
 619   // We need to initialize the region(s) we just discovered. This is
 620   // a bit tricky given that it can happen concurrently with
 621   // refinement threads refining cards on these regions and
 622   // potentially wanting to refine the BOT as they are scanning
 623   // those cards (this can happen shortly after a cleanup; see CR
 624   // 6991377). So we have to set up the region(s) carefully and in
 625   // a specific order.
 626 
 627   // The word size sum of all the regions we will allocate.
 628   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 629   assert(word_size <= word_size_sum, "sanity");
 630 
 631   // This will be the "starts humongous" region.
 632   HeapRegion* first_hr = region_at(first);
 633   // The header of the new object will be placed at the bottom of
 634   // the first region.
 635   HeapWord* new_obj = first_hr->bottom();
 636   // This will be the new end of the first region in the series that
 637   // should also match the end of the last region in the series.
 638   HeapWord* new_end = new_obj + word_size_sum;
 639   // This will be the new top of the first region that will reflect
 640   // this allocation.
 641   HeapWord* new_top = new_obj + word_size;
 642 
 643   // First, we need to zero the header of the space that we will be
 644   // allocating. When we update top further down, some refinement
 645   // threads might try to scan the region. By zeroing the header we
 646   // ensure that any thread that will try to scan the region will
 647   // come across the zero klass word and bail out.
 648   //
 649   // NOTE: It would not have been correct to have used
 650   // CollectedHeap::fill_with_object() and make the space look like
 651   // an int array. The thread that is doing the allocation will
 652   // later update the object header to a potentially different array
 653   // type and, for a very short period of time, the klass and length
 654   // fields will be inconsistent. This could cause a refinement
 655   // thread to calculate the object size incorrectly.
 656   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 657 
 658   // We will set up the first region as "starts humongous". This
 659   // will also update the BOT covering all the regions to reflect
 660   // that there is a single object that starts at the bottom of the
 661   // first region.
 662   first_hr->set_startsHumongous(new_top, new_end);
 663 
 664   // Then, if there are any, we will set up the "continues
 665   // humongous" regions.
 666   HeapRegion* hr = NULL;
 667   for (uint i = first + 1; i < last; ++i) {
 668     hr = region_at(i);
 669     hr->set_continuesHumongous(first_hr);
 670   }
 671   // If we have "continues humongous" regions (hr != NULL), then the
 672   // end of the last one should match new_end.
 673   assert(hr == NULL || hr->end() == new_end, "sanity");
 674 
 675   // Up to this point no concurrent thread would have been able to
 676   // do any scanning on any region in this series. All the top
 677   // fields still point to bottom, so the intersection between
 678   // [bottom,top] and [card_start,card_end] will be empty. Before we
 679   // update the top fields, we'll do a storestore to make sure that
 680   // no thread sees the update to top before the zeroing of the
 681   // object header and the BOT initialization.
 682   OrderAccess::storestore();
 683 
 684   // Now that the BOT and the object header have been initialized,
 685   // we can update top of the "starts humongous" region.
 686   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 687          "new_top should be in this region");
 688   first_hr->set_top(new_top);
 689   if (_hr_printer.is_active()) {
 690     HeapWord* bottom = first_hr->bottom();
 691     HeapWord* end = first_hr->orig_end();
 692     if ((first + 1) == last) {
 693       // the series has a single humongous region
 694       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 695     } else {
 696       // the series has more than one humongous regions
 697       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 698     }
 699   }
 700 
 701   // Now, we will update the top fields of the "continues humongous"
 702   // regions. The reason we need to do this is that, otherwise,
 703   // these regions would look empty and this will confuse parts of
 704   // G1. For example, the code that looks for a consecutive number
 705   // of empty regions will consider them empty and try to
 706   // re-allocate them. We can extend is_empty() to also include
 707   // !continuesHumongous(), but it is easier to just update the top
 708   // fields here. The way we set top for all regions (i.e., top ==
 709   // end for all regions but the last one, top == new_top for the
 710   // last one) is actually used when we will free up the humongous
 711   // region in free_humongous_region().
 712   hr = NULL;
 713   for (uint i = first + 1; i < last; ++i) {
 714     hr = region_at(i);
 715     if ((i + 1) == last) {
 716       // last continues humongous region
 717       assert(hr->bottom() < new_top && new_top <= hr->end(),
 718              "new_top should fall on this region");
 719       hr->set_top(new_top);
 720       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 721     } else {
 722       // not last one
 723       assert(new_top > hr->end(), "new_top should be above this region");
 724       hr->set_top(hr->end());
 725       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 726     }
 727   }
 728   // If we have continues humongous regions (hr != NULL), then the
 729   // end of the last one should match new_end and its top should
 730   // match new_top.
 731   assert(hr == NULL ||
 732          (hr->end() == new_end && hr->top() == new_top), "sanity");
 733   check_bitmaps("Humongous Region Allocation", first_hr);
 734 
 735   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 736   _summary_bytes_used += first_hr->used();
 737   _humongous_set.add(first_hr);
 738 
 739   return new_obj;
 740 }
 741 
 742 // If could fit into free regions w/o expansion, try.
 743 // Otherwise, if can expand, do so.
 744 // Otherwise, if using ex regions might help, try with ex given back.
 745 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 746   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 747 
 748   verify_region_sets_optional();
 749 
 750   uint first = G1_NO_HRS_INDEX;
 751   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 752 
 753   if (obj_regions == 1) {
 754     // Only one region to allocate, try to use a fast path by directly allocating
 755     // from the free lists. Do not try to expand here, we will potentially do that
 756     // later.
 757     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 758     if (hr != NULL) {
 759       first = hr->hrs_index();
 760     }
 761   } else {
 762     // We can't allocate humongous regions spanning more than one region while
 763     // cleanupComplete() is running, since some of the regions we find to be
 764     // empty might not yet be added to the free list. It is not straightforward
 765     // to know in which list they are on so that we can remove them. We only
 766     // need to do this if we need to allocate more than one region to satisfy the
 767     // current humongous allocation request. If we are only allocating one region
 768     // we use the one-region region allocation code (see above), that already
 769     // potentially waits for regions from the secondary free list.
 770     wait_while_free_regions_coming();
 771     append_secondary_free_list_if_not_empty_with_lock();
 772 
 773     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 774     // are lucky enough to find some.
 775     first = _hrs.find_contiguous_only_empty(obj_regions);
 776     if (first != G1_NO_HRS_INDEX) {
 777       _hrs.allocate_free_regions_starting_at(first, obj_regions);
 778     }
 779   }
 780 
 781   if (first == G1_NO_HRS_INDEX) {
 782     // Policy: We could not find enough regions for the humongous object in the
 783     // free list. Look through the heap to find a mix of free and uncommitted regions.
 784     // If so, try expansion.
 785     first = _hrs.find_contiguous_empty_or_unavailable(obj_regions);
 786     if (first != G1_NO_HRS_INDEX) {
 787       // We found something. Make sure these regions are committed, i.e. expand
 788       // the heap. Alternatively we could do a defragmentation GC.
 789       ergo_verbose1(ErgoHeapSizing,
 790                     "attempt heap expansion",
 791                     ergo_format_reason("humongous allocation request failed")
 792                     ergo_format_byte("allocation request"),
 793                     word_size * HeapWordSize);
 794 
 795       _hrs.expand_at(first, obj_regions);
 796       g1_policy()->record_new_heap_size(num_regions());
 797 
 798 #ifdef ASSERT
 799       for (uint i = first; i < first + obj_regions; ++i) {
 800         HeapRegion* hr = region_at(i);
 801         assert(hr->is_empty(), "sanity");
 802         assert(is_on_master_free_list(hr), "sanity");
 803       }
 804 #endif
 805       _hrs.allocate_free_regions_starting_at(first, obj_regions);
 806     } else {
 807       // Policy: Potentially trigger a defragmentation GC.
 808     }
 809   }
 810 
 811   HeapWord* result = NULL;
 812   if (first != G1_NO_HRS_INDEX) {
 813     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 814     assert(result != NULL, "it should always return a valid result");
 815 
 816     // A successful humongous object allocation changes the used space
 817     // information of the old generation so we need to recalculate the
 818     // sizes and update the jstat counters here.
 819     g1mm()->update_sizes();
 820   }
 821 
 822   verify_region_sets_optional();
 823 
 824   return result;
 825 }
 826 
 827 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 828   assert_heap_not_locked_and_not_at_safepoint();
 829   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 830 
 831   unsigned int dummy_gc_count_before;
 832   int dummy_gclocker_retry_count = 0;
 833   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 834 }
 835 
 836 HeapWord*
 837 G1CollectedHeap::mem_allocate(size_t word_size,
 838                               bool*  gc_overhead_limit_was_exceeded) {
 839   assert_heap_not_locked_and_not_at_safepoint();
 840 
 841   // Loop until the allocation is satisfied, or unsatisfied after GC.
 842   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 843     unsigned int gc_count_before;
 844 
 845     HeapWord* result = NULL;
 846     if (!isHumongous(word_size)) {
 847       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 848     } else {
 849       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 850     }
 851     if (result != NULL) {
 852       return result;
 853     }
 854 
 855     // Create the garbage collection operation...
 856     VM_G1CollectForAllocation op(gc_count_before, word_size);
 857     // ...and get the VM thread to execute it.
 858     VMThread::execute(&op);
 859 
 860     if (op.prologue_succeeded() && op.pause_succeeded()) {
 861       // If the operation was successful we'll return the result even
 862       // if it is NULL. If the allocation attempt failed immediately
 863       // after a Full GC, it's unlikely we'll be able to allocate now.
 864       HeapWord* result = op.result();
 865       if (result != NULL && !isHumongous(word_size)) {
 866         // Allocations that take place on VM operations do not do any
 867         // card dirtying and we have to do it here. We only have to do
 868         // this for non-humongous allocations, though.
 869         dirty_young_block(result, word_size);
 870       }
 871       return result;
 872     } else {
 873       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 874         return NULL;
 875       }
 876       assert(op.result() == NULL,
 877              "the result should be NULL if the VM op did not succeed");
 878     }
 879 
 880     // Give a warning if we seem to be looping forever.
 881     if ((QueuedAllocationWarningCount > 0) &&
 882         (try_count % QueuedAllocationWarningCount == 0)) {
 883       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 884     }
 885   }
 886 
 887   ShouldNotReachHere();
 888   return NULL;
 889 }
 890 
 891 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 892                                            unsigned int *gc_count_before_ret,
 893                                            int* gclocker_retry_count_ret) {
 894   // Make sure you read the note in attempt_allocation_humongous().
 895 
 896   assert_heap_not_locked_and_not_at_safepoint();
 897   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 898          "be called for humongous allocation requests");
 899 
 900   // We should only get here after the first-level allocation attempt
 901   // (attempt_allocation()) failed to allocate.
 902 
 903   // We will loop until a) we manage to successfully perform the
 904   // allocation or b) we successfully schedule a collection which
 905   // fails to perform the allocation. b) is the only case when we'll
 906   // return NULL.
 907   HeapWord* result = NULL;
 908   for (int try_count = 1; /* we'll return */; try_count += 1) {
 909     bool should_try_gc;
 910     unsigned int gc_count_before;
 911 
 912     {
 913       MutexLockerEx x(Heap_lock);
 914 
 915       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 916                                                       false /* bot_updates */);
 917       if (result != NULL) {
 918         return result;
 919       }
 920 
 921       // If we reach here, attempt_allocation_locked() above failed to
 922       // allocate a new region. So the mutator alloc region should be NULL.
 923       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 924 
 925       if (GC_locker::is_active_and_needs_gc()) {
 926         if (g1_policy()->can_expand_young_list()) {
 927           // No need for an ergo verbose message here,
 928           // can_expand_young_list() does this when it returns true.
 929           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 930                                                       false /* bot_updates */);
 931           if (result != NULL) {
 932             return result;
 933           }
 934         }
 935         should_try_gc = false;
 936       } else {
 937         // The GCLocker may not be active but the GCLocker initiated
 938         // GC may not yet have been performed (GCLocker::needs_gc()
 939         // returns true). In this case we do not try this GC and
 940         // wait until the GCLocker initiated GC is performed, and
 941         // then retry the allocation.
 942         if (GC_locker::needs_gc()) {
 943           should_try_gc = false;
 944         } else {
 945           // Read the GC count while still holding the Heap_lock.
 946           gc_count_before = total_collections();
 947           should_try_gc = true;
 948         }
 949       }
 950     }
 951 
 952     if (should_try_gc) {
 953       bool succeeded;
 954       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 955           GCCause::_g1_inc_collection_pause);
 956       if (result != NULL) {
 957         assert(succeeded, "only way to get back a non-NULL result");
 958         return result;
 959       }
 960 
 961       if (succeeded) {
 962         // If we get here we successfully scheduled a collection which
 963         // failed to allocate. No point in trying to allocate
 964         // further. We'll just return NULL.
 965         MutexLockerEx x(Heap_lock);
 966         *gc_count_before_ret = total_collections();
 967         return NULL;
 968       }
 969     } else {
 970       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 971         MutexLockerEx x(Heap_lock);
 972         *gc_count_before_ret = total_collections();
 973         return NULL;
 974       }
 975       // The GCLocker is either active or the GCLocker initiated
 976       // GC has not yet been performed. Stall until it is and
 977       // then retry the allocation.
 978       GC_locker::stall_until_clear();
 979       (*gclocker_retry_count_ret) += 1;
 980     }
 981 
 982     // We can reach here if we were unsuccessful in scheduling a
 983     // collection (because another thread beat us to it) or if we were
 984     // stalled due to the GC locker. In either can we should retry the
 985     // allocation attempt in case another thread successfully
 986     // performed a collection and reclaimed enough space. We do the
 987     // first attempt (without holding the Heap_lock) here and the
 988     // follow-on attempt will be at the start of the next loop
 989     // iteration (after taking the Heap_lock).
 990     result = _mutator_alloc_region.attempt_allocation(word_size,
 991                                                       false /* bot_updates */);
 992     if (result != NULL) {
 993       return result;
 994     }
 995 
 996     // Give a warning if we seem to be looping forever.
 997     if ((QueuedAllocationWarningCount > 0) &&
 998         (try_count % QueuedAllocationWarningCount == 0)) {
 999       warning("G1CollectedHeap::attempt_allocation_slow() "
1000               "retries %d times", try_count);
1001     }
1002   }
1003 
1004   ShouldNotReachHere();
1005   return NULL;
1006 }
1007 
1008 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1009                                           unsigned int * gc_count_before_ret,
1010                                           int* gclocker_retry_count_ret) {
1011   // The structure of this method has a lot of similarities to
1012   // attempt_allocation_slow(). The reason these two were not merged
1013   // into a single one is that such a method would require several "if
1014   // allocation is not humongous do this, otherwise do that"
1015   // conditional paths which would obscure its flow. In fact, an early
1016   // version of this code did use a unified method which was harder to
1017   // follow and, as a result, it had subtle bugs that were hard to
1018   // track down. So keeping these two methods separate allows each to
1019   // be more readable. It will be good to keep these two in sync as
1020   // much as possible.
1021 
1022   assert_heap_not_locked_and_not_at_safepoint();
1023   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1024          "should only be called for humongous allocations");
1025 
1026   // Humongous objects can exhaust the heap quickly, so we should check if we
1027   // need to start a marking cycle at each humongous object allocation. We do
1028   // the check before we do the actual allocation. The reason for doing it
1029   // before the allocation is that we avoid having to keep track of the newly
1030   // allocated memory while we do a GC.
1031   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1032                                            word_size)) {
1033     collect(GCCause::_g1_humongous_allocation);
1034   }
1035 
1036   // We will loop until a) we manage to successfully perform the
1037   // allocation or b) we successfully schedule a collection which
1038   // fails to perform the allocation. b) is the only case when we'll
1039   // return NULL.
1040   HeapWord* result = NULL;
1041   for (int try_count = 1; /* we'll return */; try_count += 1) {
1042     bool should_try_gc;
1043     unsigned int gc_count_before;
1044 
1045     {
1046       MutexLockerEx x(Heap_lock);
1047 
1048       // Given that humongous objects are not allocated in young
1049       // regions, we'll first try to do the allocation without doing a
1050       // collection hoping that there's enough space in the heap.
1051       result = humongous_obj_allocate(word_size);
1052       if (result != NULL) {
1053         return result;
1054       }
1055 
1056       if (GC_locker::is_active_and_needs_gc()) {
1057         should_try_gc = false;
1058       } else {
1059          // The GCLocker may not be active but the GCLocker initiated
1060         // GC may not yet have been performed (GCLocker::needs_gc()
1061         // returns true). In this case we do not try this GC and
1062         // wait until the GCLocker initiated GC is performed, and
1063         // then retry the allocation.
1064         if (GC_locker::needs_gc()) {
1065           should_try_gc = false;
1066         } else {
1067           // Read the GC count while still holding the Heap_lock.
1068           gc_count_before = total_collections();
1069           should_try_gc = true;
1070         }
1071       }
1072     }
1073 
1074     if (should_try_gc) {
1075       // If we failed to allocate the humongous object, we should try to
1076       // do a collection pause (if we're allowed) in case it reclaims
1077       // enough space for the allocation to succeed after the pause.
1078 
1079       bool succeeded;
1080       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1081           GCCause::_g1_humongous_allocation);
1082       if (result != NULL) {
1083         assert(succeeded, "only way to get back a non-NULL result");
1084         return result;
1085       }
1086 
1087       if (succeeded) {
1088         // If we get here we successfully scheduled a collection which
1089         // failed to allocate. No point in trying to allocate
1090         // further. We'll just return NULL.
1091         MutexLockerEx x(Heap_lock);
1092         *gc_count_before_ret = total_collections();
1093         return NULL;
1094       }
1095     } else {
1096       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1097         MutexLockerEx x(Heap_lock);
1098         *gc_count_before_ret = total_collections();
1099         return NULL;
1100       }
1101       // The GCLocker is either active or the GCLocker initiated
1102       // GC has not yet been performed. Stall until it is and
1103       // then retry the allocation.
1104       GC_locker::stall_until_clear();
1105       (*gclocker_retry_count_ret) += 1;
1106     }
1107 
1108     // We can reach here if we were unsuccessful in scheduling a
1109     // collection (because another thread beat us to it) or if we were
1110     // stalled due to the GC locker. In either can we should retry the
1111     // allocation attempt in case another thread successfully
1112     // performed a collection and reclaimed enough space.  Give a
1113     // warning if we seem to be looping forever.
1114 
1115     if ((QueuedAllocationWarningCount > 0) &&
1116         (try_count % QueuedAllocationWarningCount == 0)) {
1117       warning("G1CollectedHeap::attempt_allocation_humongous() "
1118               "retries %d times", try_count);
1119     }
1120   }
1121 
1122   ShouldNotReachHere();
1123   return NULL;
1124 }
1125 
1126 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1127                                        bool expect_null_mutator_alloc_region) {
1128   assert_at_safepoint(true /* should_be_vm_thread */);
1129   assert(_mutator_alloc_region.get() == NULL ||
1130                                              !expect_null_mutator_alloc_region,
1131          "the current alloc region was unexpectedly found to be non-NULL");
1132 
1133   if (!isHumongous(word_size)) {
1134     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1135                                                       false /* bot_updates */);
1136   } else {
1137     HeapWord* result = humongous_obj_allocate(word_size);
1138     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1139       g1_policy()->set_initiate_conc_mark_if_possible();
1140     }
1141     return result;
1142   }
1143 
1144   ShouldNotReachHere();
1145 }
1146 
1147 class PostMCRemSetClearClosure: public HeapRegionClosure {
1148   G1CollectedHeap* _g1h;
1149   ModRefBarrierSet* _mr_bs;
1150 public:
1151   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1152     _g1h(g1h), _mr_bs(mr_bs) {}
1153 
1154   bool doHeapRegion(HeapRegion* r) {
1155     HeapRegionRemSet* hrrs = r->rem_set();
1156 
1157     if (r->continuesHumongous()) {
1158       // We'll assert that the strong code root list and RSet is empty
1159       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1160       assert(hrrs->occupied() == 0, "RSet should be empty");
1161       return false;
1162     }
1163 
1164     _g1h->reset_gc_time_stamps(r);
1165     hrrs->clear();
1166     // You might think here that we could clear just the cards
1167     // corresponding to the used region.  But no: if we leave a dirty card
1168     // in a region we might allocate into, then it would prevent that card
1169     // from being enqueued, and cause it to be missed.
1170     // Re: the performance cost: we shouldn't be doing full GC anyway!
1171     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1172 
1173     return false;
1174   }
1175 };
1176 
1177 void G1CollectedHeap::clear_rsets_post_compaction() {
1178   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1179   heap_region_iterate(&rs_clear);
1180 }
1181 
1182 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1183   G1CollectedHeap*   _g1h;
1184   UpdateRSOopClosure _cl;
1185   int                _worker_i;
1186 public:
1187   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1188     _cl(g1->g1_rem_set(), worker_i),
1189     _worker_i(worker_i),
1190     _g1h(g1)
1191   { }
1192 
1193   bool doHeapRegion(HeapRegion* r) {
1194     if (!r->continuesHumongous()) {
1195       _cl.set_from(r);
1196       r->oop_iterate(&_cl);
1197     }
1198     return false;
1199   }
1200 };
1201 
1202 class ParRebuildRSTask: public AbstractGangTask {
1203   G1CollectedHeap* _g1;
1204 public:
1205   ParRebuildRSTask(G1CollectedHeap* g1)
1206     : AbstractGangTask("ParRebuildRSTask"),
1207       _g1(g1)
1208   { }
1209 
1210   void work(uint worker_id) {
1211     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1212     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1213                                           _g1->workers()->active_workers(),
1214                                          HeapRegion::RebuildRSClaimValue);
1215   }
1216 };
1217 
1218 class PostCompactionPrinterClosure: public HeapRegionClosure {
1219 private:
1220   G1HRPrinter* _hr_printer;
1221 public:
1222   bool doHeapRegion(HeapRegion* hr) {
1223     assert(!hr->is_young(), "not expecting to find young regions");
1224     // We only generate output for non-empty regions.
1225     if (!hr->is_empty()) {
1226       if (!hr->isHumongous()) {
1227         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1228       } else if (hr->startsHumongous()) {
1229         if (hr->region_num() == 1) {
1230           // single humongous region
1231           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1232         } else {
1233           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1234         }
1235       } else {
1236         assert(hr->continuesHumongous(), "only way to get here");
1237         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1238       }
1239     }
1240     return false;
1241   }
1242 
1243   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1244     : _hr_printer(hr_printer) { }
1245 };
1246 
1247 void G1CollectedHeap::print_hrs_post_compaction() {
1248   PostCompactionPrinterClosure cl(hr_printer());
1249   heap_region_iterate(&cl);
1250 }
1251 
1252 bool G1CollectedHeap::do_collection(bool explicit_gc,
1253                                     bool clear_all_soft_refs,
1254                                     size_t word_size) {
1255   assert_at_safepoint(true /* should_be_vm_thread */);
1256 
1257   if (GC_locker::check_active_before_gc()) {
1258     return false;
1259   }
1260 
1261   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1262   gc_timer->register_gc_start();
1263 
1264   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1265   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1266 
1267   SvcGCMarker sgcm(SvcGCMarker::FULL);
1268   ResourceMark rm;
1269 
1270   print_heap_before_gc();
1271   trace_heap_before_gc(gc_tracer);
1272 
1273   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1274 
1275   verify_region_sets_optional();
1276 
1277   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1278                            collector_policy()->should_clear_all_soft_refs();
1279 
1280   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1281 
1282   {
1283     IsGCActiveMark x;
1284 
1285     // Timing
1286     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1287     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1288     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1289 
1290     {
1291       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1292       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1293       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1294 
1295       double start = os::elapsedTime();
1296       g1_policy()->record_full_collection_start();
1297 
1298       // Note: When we have a more flexible GC logging framework that
1299       // allows us to add optional attributes to a GC log record we
1300       // could consider timing and reporting how long we wait in the
1301       // following two methods.
1302       wait_while_free_regions_coming();
1303       // If we start the compaction before the CM threads finish
1304       // scanning the root regions we might trip them over as we'll
1305       // be moving objects / updating references. So let's wait until
1306       // they are done. By telling them to abort, they should complete
1307       // early.
1308       _cm->root_regions()->abort();
1309       _cm->root_regions()->wait_until_scan_finished();
1310       append_secondary_free_list_if_not_empty_with_lock();
1311 
1312       gc_prologue(true);
1313       increment_total_collections(true /* full gc */);
1314       increment_old_marking_cycles_started();
1315 
1316       assert(used() == recalculate_used(), "Should be equal");
1317 
1318       verify_before_gc();
1319 
1320       check_bitmaps("Full GC Start");
1321       pre_full_gc_dump(gc_timer);
1322 
1323       COMPILER2_PRESENT(DerivedPointerTable::clear());
1324 
1325       // Disable discovery and empty the discovered lists
1326       // for the CM ref processor.
1327       ref_processor_cm()->disable_discovery();
1328       ref_processor_cm()->abandon_partial_discovery();
1329       ref_processor_cm()->verify_no_references_recorded();
1330 
1331       // Abandon current iterations of concurrent marking and concurrent
1332       // refinement, if any are in progress. We have to do this before
1333       // wait_until_scan_finished() below.
1334       concurrent_mark()->abort();
1335 
1336       // Make sure we'll choose a new allocation region afterwards.
1337       release_mutator_alloc_region();
1338       abandon_gc_alloc_regions();
1339       g1_rem_set()->cleanupHRRS();
1340 
1341       // We should call this after we retire any currently active alloc
1342       // regions so that all the ALLOC / RETIRE events are generated
1343       // before the start GC event.
1344       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1345 
1346       // We may have added regions to the current incremental collection
1347       // set between the last GC or pause and now. We need to clear the
1348       // incremental collection set and then start rebuilding it afresh
1349       // after this full GC.
1350       abandon_collection_set(g1_policy()->inc_cset_head());
1351       g1_policy()->clear_incremental_cset();
1352       g1_policy()->stop_incremental_cset_building();
1353 
1354       tear_down_region_sets(false /* free_list_only */);
1355       g1_policy()->set_gcs_are_young(true);
1356 
1357       // See the comments in g1CollectedHeap.hpp and
1358       // G1CollectedHeap::ref_processing_init() about
1359       // how reference processing currently works in G1.
1360 
1361       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1362       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1363 
1364       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1365       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1366 
1367       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1368       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1369 
1370       // Do collection work
1371       {
1372         HandleMark hm;  // Discard invalid handles created during gc
1373         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1374       }
1375 
1376       assert(num_free_regions() == 0, "we should not have added any free regions");
1377       rebuild_region_sets(false /* free_list_only */);
1378 
1379       // Enqueue any discovered reference objects that have
1380       // not been removed from the discovered lists.
1381       ref_processor_stw()->enqueue_discovered_references();
1382 
1383       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1384 
1385       MemoryService::track_memory_usage();
1386 
1387       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1388       ref_processor_stw()->verify_no_references_recorded();
1389 
1390       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1391       ClassLoaderDataGraph::purge();
1392       MetaspaceAux::verify_metrics();
1393 
1394       // Note: since we've just done a full GC, concurrent
1395       // marking is no longer active. Therefore we need not
1396       // re-enable reference discovery for the CM ref processor.
1397       // That will be done at the start of the next marking cycle.
1398       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1399       ref_processor_cm()->verify_no_references_recorded();
1400 
1401       reset_gc_time_stamp();
1402       // Since everything potentially moved, we will clear all remembered
1403       // sets, and clear all cards.  Later we will rebuild remembered
1404       // sets. We will also reset the GC time stamps of the regions.
1405       clear_rsets_post_compaction();
1406       check_gc_time_stamps();
1407 
1408       // Resize the heap if necessary.
1409       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1410 
1411       if (_hr_printer.is_active()) {
1412         // We should do this after we potentially resize the heap so
1413         // that all the COMMIT / UNCOMMIT events are generated before
1414         // the end GC event.
1415 
1416         print_hrs_post_compaction();
1417         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1418       }
1419 
1420       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1421       if (hot_card_cache->use_cache()) {
1422         hot_card_cache->reset_card_counts();
1423         hot_card_cache->reset_hot_cache();
1424       }
1425 
1426       // Rebuild remembered sets of all regions.
1427       if (G1CollectedHeap::use_parallel_gc_threads()) {
1428         uint n_workers =
1429           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1430                                                   workers()->active_workers(),
1431                                                   Threads::number_of_non_daemon_threads());
1432         assert(UseDynamicNumberOfGCThreads ||
1433                n_workers == workers()->total_workers(),
1434                "If not dynamic should be using all the  workers");
1435         workers()->set_active_workers(n_workers);
1436         // Set parallel threads in the heap (_n_par_threads) only
1437         // before a parallel phase and always reset it to 0 after
1438         // the phase so that the number of parallel threads does
1439         // no get carried forward to a serial phase where there
1440         // may be code that is "possibly_parallel".
1441         set_par_threads(n_workers);
1442 
1443         ParRebuildRSTask rebuild_rs_task(this);
1444         assert(check_heap_region_claim_values(
1445                HeapRegion::InitialClaimValue), "sanity check");
1446         assert(UseDynamicNumberOfGCThreads ||
1447                workers()->active_workers() == workers()->total_workers(),
1448                "Unless dynamic should use total workers");
1449         // Use the most recent number of  active workers
1450         assert(workers()->active_workers() > 0,
1451                "Active workers not properly set");
1452         set_par_threads(workers()->active_workers());
1453         workers()->run_task(&rebuild_rs_task);
1454         set_par_threads(0);
1455         assert(check_heap_region_claim_values(
1456                HeapRegion::RebuildRSClaimValue), "sanity check");
1457         reset_heap_region_claim_values();
1458       } else {
1459         RebuildRSOutOfRegionClosure rebuild_rs(this);
1460         heap_region_iterate(&rebuild_rs);
1461       }
1462 
1463       // Rebuild the strong code root lists for each region
1464       rebuild_strong_code_roots();
1465 
1466       if (true) { // FIXME
1467         MetaspaceGC::compute_new_size();
1468       }
1469 
1470 #ifdef TRACESPINNING
1471       ParallelTaskTerminator::print_termination_counts();
1472 #endif
1473 
1474       // Discard all rset updates
1475       JavaThread::dirty_card_queue_set().abandon_logs();
1476       assert(!G1DeferredRSUpdate
1477              || (G1DeferredRSUpdate &&
1478                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1479 
1480       _young_list->reset_sampled_info();
1481       // At this point there should be no regions in the
1482       // entire heap tagged as young.
1483       assert(check_young_list_empty(true /* check_heap */),
1484              "young list should be empty at this point");
1485 
1486       // Update the number of full collections that have been completed.
1487       increment_old_marking_cycles_completed(false /* concurrent */);
1488 
1489       _hrs.verify_optional();
1490       verify_region_sets_optional();
1491 
1492       verify_after_gc();
1493 
1494       // Clear the previous marking bitmap, if needed for bitmap verification.
1495       // Note we cannot do this when we clear the next marking bitmap in
1496       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1497       // objects marked during a full GC against the previous bitmap.
1498       // But we need to clear it before calling check_bitmaps below since
1499       // the full GC has compacted objects and updated TAMS but not updated
1500       // the prev bitmap.
1501       if (G1VerifyBitmaps) {
1502         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1503       }
1504       check_bitmaps("Full GC End");
1505 
1506       // Start a new incremental collection set for the next pause
1507       assert(g1_policy()->collection_set() == NULL, "must be");
1508       g1_policy()->start_incremental_cset_building();
1509 
1510       clear_cset_fast_test();
1511 
1512       init_mutator_alloc_region();
1513 
1514       double end = os::elapsedTime();
1515       g1_policy()->record_full_collection_end();
1516 
1517       if (G1Log::fine()) {
1518         g1_policy()->print_heap_transition();
1519       }
1520 
1521       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1522       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1523       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1524       // before any GC notifications are raised.
1525       g1mm()->update_sizes();
1526 
1527       gc_epilogue(true);
1528     }
1529 
1530     if (G1Log::finer()) {
1531       g1_policy()->print_detailed_heap_transition(true /* full */);
1532     }
1533 
1534     print_heap_after_gc();
1535     trace_heap_after_gc(gc_tracer);
1536 
1537     post_full_gc_dump(gc_timer);
1538 
1539     gc_timer->register_gc_end();
1540     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1541   }
1542 
1543   return true;
1544 }
1545 
1546 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1547   // do_collection() will return whether it succeeded in performing
1548   // the GC. Currently, there is no facility on the
1549   // do_full_collection() API to notify the caller than the collection
1550   // did not succeed (e.g., because it was locked out by the GC
1551   // locker). So, right now, we'll ignore the return value.
1552   bool dummy = do_collection(true,                /* explicit_gc */
1553                              clear_all_soft_refs,
1554                              0                    /* word_size */);
1555 }
1556 
1557 // This code is mostly copied from TenuredGeneration.
1558 void
1559 G1CollectedHeap::
1560 resize_if_necessary_after_full_collection(size_t word_size) {
1561   // Include the current allocation, if any, and bytes that will be
1562   // pre-allocated to support collections, as "used".
1563   const size_t used_after_gc = used();
1564   const size_t capacity_after_gc = capacity();
1565   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1566 
1567   // This is enforced in arguments.cpp.
1568   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1569          "otherwise the code below doesn't make sense");
1570 
1571   // We don't have floating point command-line arguments
1572   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1573   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1574   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1575   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1576 
1577   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1578   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1579 
1580   // We have to be careful here as these two calculations can overflow
1581   // 32-bit size_t's.
1582   double used_after_gc_d = (double) used_after_gc;
1583   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1584   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1585 
1586   // Let's make sure that they are both under the max heap size, which
1587   // by default will make them fit into a size_t.
1588   double desired_capacity_upper_bound = (double) max_heap_size;
1589   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1590                                     desired_capacity_upper_bound);
1591   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1592                                     desired_capacity_upper_bound);
1593 
1594   // We can now safely turn them into size_t's.
1595   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1596   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1597 
1598   // This assert only makes sense here, before we adjust them
1599   // with respect to the min and max heap size.
1600   assert(minimum_desired_capacity <= maximum_desired_capacity,
1601          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1602                  "maximum_desired_capacity = "SIZE_FORMAT,
1603                  minimum_desired_capacity, maximum_desired_capacity));
1604 
1605   // Should not be greater than the heap max size. No need to adjust
1606   // it with respect to the heap min size as it's a lower bound (i.e.,
1607   // we'll try to make the capacity larger than it, not smaller).
1608   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1609   // Should not be less than the heap min size. No need to adjust it
1610   // with respect to the heap max size as it's an upper bound (i.e.,
1611   // we'll try to make the capacity smaller than it, not greater).
1612   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1613 
1614   if (capacity_after_gc < minimum_desired_capacity) {
1615     // Don't expand unless it's significant
1616     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1617     ergo_verbose4(ErgoHeapSizing,
1618                   "attempt heap expansion",
1619                   ergo_format_reason("capacity lower than "
1620                                      "min desired capacity after Full GC")
1621                   ergo_format_byte("capacity")
1622                   ergo_format_byte("occupancy")
1623                   ergo_format_byte_perc("min desired capacity"),
1624                   capacity_after_gc, used_after_gc,
1625                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1626     expand(expand_bytes);
1627 
1628     // No expansion, now see if we want to shrink
1629   } else if (capacity_after_gc > maximum_desired_capacity) {
1630     // Capacity too large, compute shrinking size
1631     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1632     ergo_verbose4(ErgoHeapSizing,
1633                   "attempt heap shrinking",
1634                   ergo_format_reason("capacity higher than "
1635                                      "max desired capacity after Full GC")
1636                   ergo_format_byte("capacity")
1637                   ergo_format_byte("occupancy")
1638                   ergo_format_byte_perc("max desired capacity"),
1639                   capacity_after_gc, used_after_gc,
1640                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1641     shrink(shrink_bytes);
1642   }
1643 }
1644 
1645 
1646 HeapWord*
1647 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1648                                            bool* succeeded) {
1649   assert_at_safepoint(true /* should_be_vm_thread */);
1650 
1651   *succeeded = true;
1652   // Let's attempt the allocation first.
1653   HeapWord* result =
1654     attempt_allocation_at_safepoint(word_size,
1655                                  false /* expect_null_mutator_alloc_region */);
1656   if (result != NULL) {
1657     assert(*succeeded, "sanity");
1658     return result;
1659   }
1660 
1661   // In a G1 heap, we're supposed to keep allocation from failing by
1662   // incremental pauses.  Therefore, at least for now, we'll favor
1663   // expansion over collection.  (This might change in the future if we can
1664   // do something smarter than full collection to satisfy a failed alloc.)
1665   result = expand_and_allocate(word_size);
1666   if (result != NULL) {
1667     assert(*succeeded, "sanity");
1668     return result;
1669   }
1670 
1671   // Expansion didn't work, we'll try to do a Full GC.
1672   bool gc_succeeded = do_collection(false, /* explicit_gc */
1673                                     false, /* clear_all_soft_refs */
1674                                     word_size);
1675   if (!gc_succeeded) {
1676     *succeeded = false;
1677     return NULL;
1678   }
1679 
1680   // Retry the allocation
1681   result = attempt_allocation_at_safepoint(word_size,
1682                                   true /* expect_null_mutator_alloc_region */);
1683   if (result != NULL) {
1684     assert(*succeeded, "sanity");
1685     return result;
1686   }
1687 
1688   // Then, try a Full GC that will collect all soft references.
1689   gc_succeeded = do_collection(false, /* explicit_gc */
1690                                true,  /* clear_all_soft_refs */
1691                                word_size);
1692   if (!gc_succeeded) {
1693     *succeeded = false;
1694     return NULL;
1695   }
1696 
1697   // Retry the allocation once more
1698   result = attempt_allocation_at_safepoint(word_size,
1699                                   true /* expect_null_mutator_alloc_region */);
1700   if (result != NULL) {
1701     assert(*succeeded, "sanity");
1702     return result;
1703   }
1704 
1705   assert(!collector_policy()->should_clear_all_soft_refs(),
1706          "Flag should have been handled and cleared prior to this point");
1707 
1708   // What else?  We might try synchronous finalization later.  If the total
1709   // space available is large enough for the allocation, then a more
1710   // complete compaction phase than we've tried so far might be
1711   // appropriate.
1712   assert(*succeeded, "sanity");
1713   return NULL;
1714 }
1715 
1716 // Attempting to expand the heap sufficiently
1717 // to support an allocation of the given "word_size".  If
1718 // successful, perform the allocation and return the address of the
1719 // allocated block, or else "NULL".
1720 
1721 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1722   assert_at_safepoint(true /* should_be_vm_thread */);
1723 
1724   verify_region_sets_optional();
1725 
1726   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1727   ergo_verbose1(ErgoHeapSizing,
1728                 "attempt heap expansion",
1729                 ergo_format_reason("allocation request failed")
1730                 ergo_format_byte("allocation request"),
1731                 word_size * HeapWordSize);
1732   if (expand(expand_bytes)) {
1733     _hrs.verify_optional();
1734     verify_region_sets_optional();
1735     return attempt_allocation_at_safepoint(word_size,
1736                                  false /* expect_null_mutator_alloc_region */);
1737   }
1738   return NULL;
1739 }
1740 
1741 bool G1CollectedHeap::expand(size_t expand_bytes) {
1742   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1743   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1744                                        HeapRegion::GrainBytes);
1745   ergo_verbose2(ErgoHeapSizing,
1746                 "expand the heap",
1747                 ergo_format_byte("requested expansion amount")
1748                 ergo_format_byte("attempted expansion amount"),
1749                 expand_bytes, aligned_expand_bytes);
1750 
1751   if (is_maximal_no_gc()) {
1752     ergo_verbose0(ErgoHeapSizing,
1753                       "did not expand the heap",
1754                       ergo_format_reason("heap already fully expanded"));
1755     return false;
1756   }
1757 
1758   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1759   assert(regions_to_expand > 0, "Must expand by at least one region");
1760 
1761   uint expanded_by = _hrs.expand_by(regions_to_expand);
1762 
1763   if (expanded_by > 0) {
1764     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1765     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1766     g1_policy()->record_new_heap_size(num_regions());
1767   } else {
1768     ergo_verbose0(ErgoHeapSizing,
1769                   "did not expand the heap",
1770                   ergo_format_reason("heap expansion operation failed"));
1771     // The expansion of the virtual storage space was unsuccessful.
1772     // Let's see if it was because we ran out of swap.
1773     if (G1ExitOnExpansionFailure &&
1774         _hrs.available() >= regions_to_expand) {
1775       // We had head room...
1776       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1777     }
1778   }
1779   return regions_to_expand > 0;
1780 }
1781 
1782 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1783   size_t aligned_shrink_bytes =
1784     ReservedSpace::page_align_size_down(shrink_bytes);
1785   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1786                                          HeapRegion::GrainBytes);
1787   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1788 
1789   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1790   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1791 
1792   ergo_verbose3(ErgoHeapSizing,
1793                 "shrink the heap",
1794                 ergo_format_byte("requested shrinking amount")
1795                 ergo_format_byte("aligned shrinking amount")
1796                 ergo_format_byte("attempted shrinking amount"),
1797                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1798   if (num_regions_removed > 0) {
1799     g1_policy()->record_new_heap_size(num_regions());
1800   } else {
1801     ergo_verbose0(ErgoHeapSizing,
1802                   "did not shrink the heap",
1803                   ergo_format_reason("heap shrinking operation failed"));
1804   }
1805 }
1806 
1807 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1808   verify_region_sets_optional();
1809 
1810   // We should only reach here at the end of a Full GC which means we
1811   // should not not be holding to any GC alloc regions. The method
1812   // below will make sure of that and do any remaining clean up.
1813   abandon_gc_alloc_regions();
1814 
1815   // Instead of tearing down / rebuilding the free lists here, we
1816   // could instead use the remove_all_pending() method on free_list to
1817   // remove only the ones that we need to remove.
1818   tear_down_region_sets(true /* free_list_only */);
1819   shrink_helper(shrink_bytes);
1820   rebuild_region_sets(true /* free_list_only */);
1821 
1822   _hrs.verify_optional();
1823   verify_region_sets_optional();
1824 }
1825 
1826 // Public methods.
1827 
1828 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1829 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1830 #endif // _MSC_VER
1831 
1832 
1833 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1834   SharedHeap(policy_),
1835   _g1_policy(policy_),
1836   _dirty_card_queue_set(false),
1837   _into_cset_dirty_card_queue_set(false),
1838   _is_alive_closure_cm(this),
1839   _is_alive_closure_stw(this),
1840   _ref_processor_cm(NULL),
1841   _ref_processor_stw(NULL),
1842   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1843   _bot_shared(NULL),
1844   _evac_failure_scan_stack(NULL),
1845   _mark_in_progress(false),
1846   _cg1r(NULL), _summary_bytes_used(0),
1847   _g1mm(NULL),
1848   _refine_cte_cl(NULL),
1849   _full_collection(false),
1850   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1851   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1852   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1853   _humongous_is_live(),
1854   _has_humongous_reclaim_candidates(false),
1855   _free_regions_coming(false),
1856   _young_list(new YoungList(this)),
1857   _gc_time_stamp(0),
1858   _retained_old_gc_alloc_region(NULL),
1859   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1860   _old_plab_stats(OldPLABSize, PLABWeight),
1861   _expand_heap_after_alloc_failure(true),
1862   _surviving_young_words(NULL),
1863   _old_marking_cycles_started(0),
1864   _old_marking_cycles_completed(0),
1865   _concurrent_cycle_started(false),
1866   _in_cset_fast_test(),
1867   _dirty_cards_region_list(NULL),
1868   _worker_cset_start_region(NULL),
1869   _worker_cset_start_region_time_stamp(NULL),
1870   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1871   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1872   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1873   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1874 
1875   _g1h = this;
1876   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1877     vm_exit_during_initialization("Failed necessary allocation.");
1878   }
1879 
1880   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1881 
1882   int n_queues = MAX2((int)ParallelGCThreads, 1);
1883   _task_queues = new RefToScanQueueSet(n_queues);
1884 
1885   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1886   assert(n_rem_sets > 0, "Invariant.");
1887 
1888   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1889   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1890   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1891 
1892   for (int i = 0; i < n_queues; i++) {
1893     RefToScanQueue* q = new RefToScanQueue();
1894     q->initialize();
1895     _task_queues->register_queue(i, q);
1896     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1897   }
1898   clear_cset_start_regions();
1899 
1900   // Initialize the G1EvacuationFailureALot counters and flags.
1901   NOT_PRODUCT(reset_evacuation_should_fail();)
1902 
1903   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1904 }
1905 
1906 jint G1CollectedHeap::initialize() {
1907   CollectedHeap::pre_initialize();
1908   os::enable_vtime();
1909 
1910   G1Log::init();
1911 
1912   // Necessary to satisfy locking discipline assertions.
1913 
1914   MutexLocker x(Heap_lock);
1915 
1916   // We have to initialize the printer before committing the heap, as
1917   // it will be used then.
1918   _hr_printer.set_active(G1PrintHeapRegions);
1919 
1920   // While there are no constraints in the GC code that HeapWordSize
1921   // be any particular value, there are multiple other areas in the
1922   // system which believe this to be true (e.g. oop->object_size in some
1923   // cases incorrectly returns the size in wordSize units rather than
1924   // HeapWordSize).
1925   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1926 
1927   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1928   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1929   size_t heap_alignment = collector_policy()->heap_alignment();
1930 
1931   // Ensure that the sizes are properly aligned.
1932   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1933   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1934   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1935 
1936   _refine_cte_cl = new RefineCardTableEntryClosure();
1937 
1938   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1939 
1940   // Reserve the maximum.
1941 
1942   // When compressed oops are enabled, the preferred heap base
1943   // is calculated by subtracting the requested size from the
1944   // 32Gb boundary and using the result as the base address for
1945   // heap reservation. If the requested size is not aligned to
1946   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1947   // into the ReservedHeapSpace constructor) then the actual
1948   // base of the reserved heap may end up differing from the
1949   // address that was requested (i.e. the preferred heap base).
1950   // If this happens then we could end up using a non-optimal
1951   // compressed oops mode.
1952 
1953   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1954                                                  heap_alignment);
1955 
1956   // It is important to do this in a way such that concurrent readers can't
1957   // temporarily think something is in the heap.  (I've actually seen this
1958   // happen in asserts: DLD.)
1959   _reserved.set_word_size(0);
1960   _reserved.set_start((HeapWord*)heap_rs.base());
1961   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1962 
1963   // Create the gen rem set (and barrier set) for the entire reserved region.
1964   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1965   set_barrier_set(rem_set()->bs());
1966   if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1967     vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1968     return JNI_ENOMEM;
1969   }
1970 
1971   // Also create a G1 rem set.
1972   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1973 
1974   // Carve out the G1 part of the heap.
1975 
1976   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1977   G1RegionToSpaceMapper* heap_storage =
1978     G1RegionToSpaceMapper::create_mapper(g1_rs,
1979                                          UseLargePages ? os::large_page_size() : os::vm_page_size(),
1980                                          HeapRegion::GrainBytes,
1981                                          1,
1982                                          mtJavaHeap);
1983   heap_storage->set_mapping_changed_listener(&_listener);
1984 
1985   // Reserve space for the block offset table. We do not support automatic uncommit
1986   // for the card table at this time. BOT only.
1987   ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1988   G1RegionToSpaceMapper* bot_storage =
1989     G1RegionToSpaceMapper::create_mapper(bot_rs,
1990                                          os::vm_page_size(),
1991                                          HeapRegion::GrainBytes,
1992                                          G1BlockOffsetSharedArray::N_bytes,
1993                                          mtGC);
1994 
1995   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1996   G1RegionToSpaceMapper* cardtable_storage =
1997     G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1998                                          os::vm_page_size(),
1999                                          HeapRegion::GrainBytes,
2000                                          G1BlockOffsetSharedArray::N_bytes,
2001                                          mtGC);
2002 
2003   // Reserve space for the card counts table.
2004   ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
2005   G1RegionToSpaceMapper* card_counts_storage =
2006     G1RegionToSpaceMapper::create_mapper(card_counts_rs,
2007                                          os::vm_page_size(),
2008                                          HeapRegion::GrainBytes,
2009                                          G1BlockOffsetSharedArray::N_bytes,
2010                                          mtGC);
2011 
2012   // Reserve space for prev and next bitmap.
2013   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2014 
2015   ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2016   G1RegionToSpaceMapper* prev_bitmap_storage =
2017     G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
2018                                          os::vm_page_size(),
2019                                          HeapRegion::GrainBytes,
2020                                          CMBitMap::mark_distance(),
2021                                          mtGC);
2022 
2023   ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2024   G1RegionToSpaceMapper* next_bitmap_storage =
2025     G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
2026                                          os::vm_page_size(),
2027                                          HeapRegion::GrainBytes,
2028                                          CMBitMap::mark_distance(),
2029                                          mtGC);
2030 
2031   _hrs.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2032   g1_barrier_set()->initialize(cardtable_storage);
2033    // Do later initialization work for concurrent refinement.
2034   _cg1r->init(card_counts_storage);
2035 
2036   // 6843694 - ensure that the maximum region index can fit
2037   // in the remembered set structures.
2038   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2039   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2040 
2041   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2042   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2043   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2044             "too many cards per region");
2045 
2046   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2047 
2048   _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
2049 
2050   _g1h = this;
2051 
2052   _in_cset_fast_test.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes);
2053   _humongous_is_live.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes);
2054 
2055   // Create the ConcurrentMark data structure and thread.
2056   // (Must do this late, so that "max_regions" is defined.)
2057   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2058   if (_cm == NULL || !_cm->completed_initialization()) {
2059     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2060     return JNI_ENOMEM;
2061   }
2062   _cmThread = _cm->cmThread();
2063 
2064   // Initialize the from_card cache structure of HeapRegionRemSet.
2065   HeapRegionRemSet::init_heap(max_regions());
2066 
2067   // Now expand into the initial heap size.
2068   if (!expand(init_byte_size)) {
2069     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2070     return JNI_ENOMEM;
2071   }
2072 
2073   // Perform any initialization actions delegated to the policy.
2074   g1_policy()->init();
2075 
2076   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2077                                                SATB_Q_FL_lock,
2078                                                G1SATBProcessCompletedThreshold,
2079                                                Shared_SATB_Q_lock);
2080 
2081   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2082                                                 DirtyCardQ_CBL_mon,
2083                                                 DirtyCardQ_FL_lock,
2084                                                 concurrent_g1_refine()->yellow_zone(),
2085                                                 concurrent_g1_refine()->red_zone(),
2086                                                 Shared_DirtyCardQ_lock);
2087 
2088   if (G1DeferredRSUpdate) {
2089     dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2090                                       DirtyCardQ_CBL_mon,
2091                                       DirtyCardQ_FL_lock,
2092                                       -1, // never trigger processing
2093                                       -1, // no limit on length
2094                                       Shared_DirtyCardQ_lock,
2095                                       &JavaThread::dirty_card_queue_set());
2096   }
2097 
2098   // Initialize the card queue set used to hold cards containing
2099   // references into the collection set.
2100   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2101                                              DirtyCardQ_CBL_mon,
2102                                              DirtyCardQ_FL_lock,
2103                                              -1, // never trigger processing
2104                                              -1, // no limit on length
2105                                              Shared_DirtyCardQ_lock,
2106                                              &JavaThread::dirty_card_queue_set());
2107 
2108   // In case we're keeping closure specialization stats, initialize those
2109   // counts and that mechanism.
2110   SpecializationStats::clear();
2111 
2112   // Here we allocate the dummy HeapRegion that is required by the
2113   // G1AllocRegion class.
2114   HeapRegion* dummy_region = _hrs.get_dummy_region();
2115 
2116   // We'll re-use the same region whether the alloc region will
2117   // require BOT updates or not and, if it doesn't, then a non-young
2118   // region will complain that it cannot support allocations without
2119   // BOT updates. So we'll tag the dummy region as young to avoid that.
2120   dummy_region->set_young();
2121   // Make sure it's full.
2122   dummy_region->set_top(dummy_region->end());
2123   G1AllocRegion::setup(this, dummy_region);
2124 
2125   init_mutator_alloc_region();
2126 
2127   // Do create of the monitoring and management support so that
2128   // values in the heap have been properly initialized.
2129   _g1mm = new G1MonitoringSupport(this);
2130 
2131   G1StringDedup::initialize();
2132 
2133   return JNI_OK;
2134 }
2135 
2136 void G1CollectedHeap::stop() {
2137   // Stop all concurrent threads. We do this to make sure these threads
2138   // do not continue to execute and access resources (e.g. gclog_or_tty)
2139   // that are destroyed during shutdown.
2140   _cg1r->stop();
2141   _cmThread->stop();
2142   if (G1StringDedup::is_enabled()) {
2143     G1StringDedup::stop();
2144   }
2145 }
2146 
2147 void G1CollectedHeap::clear_humongous_is_live_table() {
2148   guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2149   _humongous_is_live.clear();
2150 }
2151 
2152 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2153   return HeapRegion::max_region_size();
2154 }
2155 
2156 void G1CollectedHeap::ref_processing_init() {
2157   // Reference processing in G1 currently works as follows:
2158   //
2159   // * There are two reference processor instances. One is
2160   //   used to record and process discovered references
2161   //   during concurrent marking; the other is used to
2162   //   record and process references during STW pauses
2163   //   (both full and incremental).
2164   // * Both ref processors need to 'span' the entire heap as
2165   //   the regions in the collection set may be dotted around.
2166   //
2167   // * For the concurrent marking ref processor:
2168   //   * Reference discovery is enabled at initial marking.
2169   //   * Reference discovery is disabled and the discovered
2170   //     references processed etc during remarking.
2171   //   * Reference discovery is MT (see below).
2172   //   * Reference discovery requires a barrier (see below).
2173   //   * Reference processing may or may not be MT
2174   //     (depending on the value of ParallelRefProcEnabled
2175   //     and ParallelGCThreads).
2176   //   * A full GC disables reference discovery by the CM
2177   //     ref processor and abandons any entries on it's
2178   //     discovered lists.
2179   //
2180   // * For the STW processor:
2181   //   * Non MT discovery is enabled at the start of a full GC.
2182   //   * Processing and enqueueing during a full GC is non-MT.
2183   //   * During a full GC, references are processed after marking.
2184   //
2185   //   * Discovery (may or may not be MT) is enabled at the start
2186   //     of an incremental evacuation pause.
2187   //   * References are processed near the end of a STW evacuation pause.
2188   //   * For both types of GC:
2189   //     * Discovery is atomic - i.e. not concurrent.
2190   //     * Reference discovery will not need a barrier.
2191 
2192   SharedHeap::ref_processing_init();
2193   MemRegion mr = reserved_region();
2194 
2195   // Concurrent Mark ref processor
2196   _ref_processor_cm =
2197     new ReferenceProcessor(mr,    // span
2198                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2199                                 // mt processing
2200                            (int) ParallelGCThreads,
2201                                 // degree of mt processing
2202                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2203                                 // mt discovery
2204                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2205                                 // degree of mt discovery
2206                            false,
2207                                 // Reference discovery is not atomic
2208                            &_is_alive_closure_cm);
2209                                 // is alive closure
2210                                 // (for efficiency/performance)
2211 
2212   // STW ref processor
2213   _ref_processor_stw =
2214     new ReferenceProcessor(mr,    // span
2215                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2216                                 // mt processing
2217                            MAX2((int)ParallelGCThreads, 1),
2218                                 // degree of mt processing
2219                            (ParallelGCThreads > 1),
2220                                 // mt discovery
2221                            MAX2((int)ParallelGCThreads, 1),
2222                                 // degree of mt discovery
2223                            true,
2224                                 // Reference discovery is atomic
2225                            &_is_alive_closure_stw);
2226                                 // is alive closure
2227                                 // (for efficiency/performance)
2228 }
2229 
2230 size_t G1CollectedHeap::capacity() const {
2231   return _hrs.length() * HeapRegion::GrainBytes;
2232 }
2233 
2234 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2235   assert(!hr->continuesHumongous(), "pre-condition");
2236   hr->reset_gc_time_stamp();
2237   if (hr->startsHumongous()) {
2238     uint first_index = hr->hrs_index() + 1;
2239     uint last_index = hr->last_hc_index();
2240     for (uint i = first_index; i < last_index; i += 1) {
2241       HeapRegion* chr = region_at(i);
2242       assert(chr->continuesHumongous(), "sanity");
2243       chr->reset_gc_time_stamp();
2244     }
2245   }
2246 }
2247 
2248 #ifndef PRODUCT
2249 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2250 private:
2251   unsigned _gc_time_stamp;
2252   bool _failures;
2253 
2254 public:
2255   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2256     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2257 
2258   virtual bool doHeapRegion(HeapRegion* hr) {
2259     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2260     if (_gc_time_stamp != region_gc_time_stamp) {
2261       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2262                              "expected %d", HR_FORMAT_PARAMS(hr),
2263                              region_gc_time_stamp, _gc_time_stamp);
2264       _failures = true;
2265     }
2266     return false;
2267   }
2268 
2269   bool failures() { return _failures; }
2270 };
2271 
2272 void G1CollectedHeap::check_gc_time_stamps() {
2273   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2274   heap_region_iterate(&cl);
2275   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2276 }
2277 #endif // PRODUCT
2278 
2279 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2280                                                  DirtyCardQueue* into_cset_dcq,
2281                                                  bool concurrent,
2282                                                  uint worker_i) {
2283   // Clean cards in the hot card cache
2284   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2285   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2286 
2287   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2288   int n_completed_buffers = 0;
2289   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2290     n_completed_buffers++;
2291   }
2292   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2293   dcqs.clear_n_completed_buffers();
2294   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2295 }
2296 
2297 
2298 // Computes the sum of the storage used by the various regions.
2299 
2300 size_t G1CollectedHeap::used() const {
2301   assert(Heap_lock->owner() != NULL,
2302          "Should be owned on this thread's behalf.");
2303   size_t result = _summary_bytes_used;
2304   // Read only once in case it is set to NULL concurrently
2305   HeapRegion* hr = _mutator_alloc_region.get();
2306   if (hr != NULL)
2307     result += hr->used();
2308   return result;
2309 }
2310 
2311 size_t G1CollectedHeap::used_unlocked() const {
2312   size_t result = _summary_bytes_used;
2313   return result;
2314 }
2315 
2316 class SumUsedClosure: public HeapRegionClosure {
2317   size_t _used;
2318 public:
2319   SumUsedClosure() : _used(0) {}
2320   bool doHeapRegion(HeapRegion* r) {
2321     if (!r->continuesHumongous()) {
2322       _used += r->used();
2323     }
2324     return false;
2325   }
2326   size_t result() { return _used; }
2327 };
2328 
2329 size_t G1CollectedHeap::recalculate_used() const {
2330   double recalculate_used_start = os::elapsedTime();
2331 
2332   SumUsedClosure blk;
2333   heap_region_iterate(&blk);
2334 
2335   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2336   return blk.result();
2337 }
2338 
2339 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2340   switch (cause) {
2341     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2342     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2343     case GCCause::_g1_humongous_allocation: return true;
2344     default:                                return false;
2345   }
2346 }
2347 
2348 #ifndef PRODUCT
2349 void G1CollectedHeap::allocate_dummy_regions() {
2350   // Let's fill up most of the region
2351   size_t word_size = HeapRegion::GrainWords - 1024;
2352   // And as a result the region we'll allocate will be humongous.
2353   guarantee(isHumongous(word_size), "sanity");
2354 
2355   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2356     // Let's use the existing mechanism for the allocation
2357     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2358     if (dummy_obj != NULL) {
2359       MemRegion mr(dummy_obj, word_size);
2360       CollectedHeap::fill_with_object(mr);
2361     } else {
2362       // If we can't allocate once, we probably cannot allocate
2363       // again. Let's get out of the loop.
2364       break;
2365     }
2366   }
2367 }
2368 #endif // !PRODUCT
2369 
2370 void G1CollectedHeap::increment_old_marking_cycles_started() {
2371   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2372     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2373     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2374     _old_marking_cycles_started, _old_marking_cycles_completed));
2375 
2376   _old_marking_cycles_started++;
2377 }
2378 
2379 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2380   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2381 
2382   // We assume that if concurrent == true, then the caller is a
2383   // concurrent thread that was joined the Suspendible Thread
2384   // Set. If there's ever a cheap way to check this, we should add an
2385   // assert here.
2386 
2387   // Given that this method is called at the end of a Full GC or of a
2388   // concurrent cycle, and those can be nested (i.e., a Full GC can
2389   // interrupt a concurrent cycle), the number of full collections
2390   // completed should be either one (in the case where there was no
2391   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2392   // behind the number of full collections started.
2393 
2394   // This is the case for the inner caller, i.e. a Full GC.
2395   assert(concurrent ||
2396          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2397          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2398          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2399                  "is inconsistent with _old_marking_cycles_completed = %u",
2400                  _old_marking_cycles_started, _old_marking_cycles_completed));
2401 
2402   // This is the case for the outer caller, i.e. the concurrent cycle.
2403   assert(!concurrent ||
2404          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2405          err_msg("for outer caller (concurrent cycle): "
2406                  "_old_marking_cycles_started = %u "
2407                  "is inconsistent with _old_marking_cycles_completed = %u",
2408                  _old_marking_cycles_started, _old_marking_cycles_completed));
2409 
2410   _old_marking_cycles_completed += 1;
2411 
2412   // We need to clear the "in_progress" flag in the CM thread before
2413   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2414   // is set) so that if a waiter requests another System.gc() it doesn't
2415   // incorrectly see that a marking cycle is still in progress.
2416   if (concurrent) {
2417     _cmThread->clear_in_progress();
2418   }
2419 
2420   // This notify_all() will ensure that a thread that called
2421   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2422   // and it's waiting for a full GC to finish will be woken up. It is
2423   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2424   FullGCCount_lock->notify_all();
2425 }
2426 
2427 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2428   _concurrent_cycle_started = true;
2429   _gc_timer_cm->register_gc_start(start_time);
2430 
2431   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2432   trace_heap_before_gc(_gc_tracer_cm);
2433 }
2434 
2435 void G1CollectedHeap::register_concurrent_cycle_end() {
2436   if (_concurrent_cycle_started) {
2437     if (_cm->has_aborted()) {
2438       _gc_tracer_cm->report_concurrent_mode_failure();
2439     }
2440 
2441     _gc_timer_cm->register_gc_end();
2442     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2443 
2444     _concurrent_cycle_started = false;
2445   }
2446 }
2447 
2448 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2449   if (_concurrent_cycle_started) {
2450     trace_heap_after_gc(_gc_tracer_cm);
2451   }
2452 }
2453 
2454 G1YCType G1CollectedHeap::yc_type() {
2455   bool is_young = g1_policy()->gcs_are_young();
2456   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2457   bool is_during_mark = mark_in_progress();
2458 
2459   if (is_initial_mark) {
2460     return InitialMark;
2461   } else if (is_during_mark) {
2462     return DuringMark;
2463   } else if (is_young) {
2464     return Normal;
2465   } else {
2466     return Mixed;
2467   }
2468 }
2469 
2470 void G1CollectedHeap::collect(GCCause::Cause cause) {
2471   assert_heap_not_locked();
2472 
2473   unsigned int gc_count_before;
2474   unsigned int old_marking_count_before;
2475   bool retry_gc;
2476 
2477   do {
2478     retry_gc = false;
2479 
2480     {
2481       MutexLocker ml(Heap_lock);
2482 
2483       // Read the GC count while holding the Heap_lock
2484       gc_count_before = total_collections();
2485       old_marking_count_before = _old_marking_cycles_started;
2486     }
2487 
2488     if (should_do_concurrent_full_gc(cause)) {
2489       // Schedule an initial-mark evacuation pause that will start a
2490       // concurrent cycle. We're setting word_size to 0 which means that
2491       // we are not requesting a post-GC allocation.
2492       VM_G1IncCollectionPause op(gc_count_before,
2493                                  0,     /* word_size */
2494                                  true,  /* should_initiate_conc_mark */
2495                                  g1_policy()->max_pause_time_ms(),
2496                                  cause);
2497 
2498       VMThread::execute(&op);
2499       if (!op.pause_succeeded()) {
2500         if (old_marking_count_before == _old_marking_cycles_started) {
2501           retry_gc = op.should_retry_gc();
2502         } else {
2503           // A Full GC happened while we were trying to schedule the
2504           // initial-mark GC. No point in starting a new cycle given
2505           // that the whole heap was collected anyway.
2506         }
2507 
2508         if (retry_gc) {
2509           if (GC_locker::is_active_and_needs_gc()) {
2510             GC_locker::stall_until_clear();
2511           }
2512         }
2513       }
2514     } else {
2515       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2516           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2517 
2518         // Schedule a standard evacuation pause. We're setting word_size
2519         // to 0 which means that we are not requesting a post-GC allocation.
2520         VM_G1IncCollectionPause op(gc_count_before,
2521                                    0,     /* word_size */
2522                                    false, /* should_initiate_conc_mark */
2523                                    g1_policy()->max_pause_time_ms(),
2524                                    cause);
2525         VMThread::execute(&op);
2526       } else {
2527         // Schedule a Full GC.
2528         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2529         VMThread::execute(&op);
2530       }
2531     }
2532   } while (retry_gc);
2533 }
2534 
2535 bool G1CollectedHeap::is_in(const void* p) const {
2536   if (_hrs.reserved().contains(p)) {
2537     // Given that we know that p is in the reserved space,
2538     // heap_region_containing_raw() should successfully
2539     // return the containing region.
2540     HeapRegion* hr = heap_region_containing_raw(p);
2541     return hr->is_in(p);
2542   } else {
2543     return false;
2544   }
2545 }
2546 
2547 #ifdef ASSERT
2548 bool G1CollectedHeap::is_in_exact(const void* p) const {
2549   bool contains = reserved_region().contains(p);
2550   bool available = _hrs.is_available(addr_to_region((HeapWord*)p));
2551   if (contains && available) {
2552     return true;
2553   } else {
2554     return false;
2555   }
2556 }
2557 #endif
2558 
2559 // Iteration functions.
2560 
2561 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2562 
2563 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2564   ExtendedOopClosure* _cl;
2565 public:
2566   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2567   bool doHeapRegion(HeapRegion* r) {
2568     if (!r->continuesHumongous()) {
2569       r->oop_iterate(_cl);
2570     }
2571     return false;
2572   }
2573 };
2574 
2575 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2576   IterateOopClosureRegionClosure blk(cl);
2577   heap_region_iterate(&blk);
2578 }
2579 
2580 // Iterates an ObjectClosure over all objects within a HeapRegion.
2581 
2582 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2583   ObjectClosure* _cl;
2584 public:
2585   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2586   bool doHeapRegion(HeapRegion* r) {
2587     if (! r->continuesHumongous()) {
2588       r->object_iterate(_cl);
2589     }
2590     return false;
2591   }
2592 };
2593 
2594 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2595   IterateObjectClosureRegionClosure blk(cl);
2596   heap_region_iterate(&blk);
2597 }
2598 
2599 // Calls a SpaceClosure on a HeapRegion.
2600 
2601 class SpaceClosureRegionClosure: public HeapRegionClosure {
2602   SpaceClosure* _cl;
2603 public:
2604   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2605   bool doHeapRegion(HeapRegion* r) {
2606     _cl->do_space(r);
2607     return false;
2608   }
2609 };
2610 
2611 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2612   SpaceClosureRegionClosure blk(cl);
2613   heap_region_iterate(&blk);
2614 }
2615 
2616 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2617   _hrs.iterate(cl);
2618 }
2619 
2620 void
2621 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2622                                                  uint worker_id,
2623                                                  uint num_workers,
2624                                                  jint claim_value) const {
2625   _hrs.par_iterate(cl, worker_id, num_workers, claim_value);
2626 }
2627 
2628 class ResetClaimValuesClosure: public HeapRegionClosure {
2629 public:
2630   bool doHeapRegion(HeapRegion* r) {
2631     r->set_claim_value(HeapRegion::InitialClaimValue);
2632     return false;
2633   }
2634 };
2635 
2636 void G1CollectedHeap::reset_heap_region_claim_values() {
2637   ResetClaimValuesClosure blk;
2638   heap_region_iterate(&blk);
2639 }
2640 
2641 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2642   ResetClaimValuesClosure blk;
2643   collection_set_iterate(&blk);
2644 }
2645 
2646 #ifdef ASSERT
2647 // This checks whether all regions in the heap have the correct claim
2648 // value. I also piggy-backed on this a check to ensure that the
2649 // humongous_start_region() information on "continues humongous"
2650 // regions is correct.
2651 
2652 class CheckClaimValuesClosure : public HeapRegionClosure {
2653 private:
2654   jint _claim_value;
2655   uint _failures;
2656   HeapRegion* _sh_region;
2657 
2658 public:
2659   CheckClaimValuesClosure(jint claim_value) :
2660     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2661   bool doHeapRegion(HeapRegion* r) {
2662     if (r->claim_value() != _claim_value) {
2663       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2664                              "claim value = %d, should be %d",
2665                              HR_FORMAT_PARAMS(r),
2666                              r->claim_value(), _claim_value);
2667       ++_failures;
2668     }
2669     if (!r->isHumongous()) {
2670       _sh_region = NULL;
2671     } else if (r->startsHumongous()) {
2672       _sh_region = r;
2673     } else if (r->continuesHumongous()) {
2674       if (r->humongous_start_region() != _sh_region) {
2675         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2676                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2677                                HR_FORMAT_PARAMS(r),
2678                                r->humongous_start_region(),
2679                                _sh_region);
2680         ++_failures;
2681       }
2682     }
2683     return false;
2684   }
2685   uint failures() { return _failures; }
2686 };
2687 
2688 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2689   CheckClaimValuesClosure cl(claim_value);
2690   heap_region_iterate(&cl);
2691   return cl.failures() == 0;
2692 }
2693 
2694 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2695 private:
2696   jint _claim_value;
2697   uint _failures;
2698 
2699 public:
2700   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2701     _claim_value(claim_value), _failures(0) { }
2702 
2703   uint failures() { return _failures; }
2704 
2705   bool doHeapRegion(HeapRegion* hr) {
2706     assert(hr->in_collection_set(), "how?");
2707     assert(!hr->isHumongous(), "H-region in CSet");
2708     if (hr->claim_value() != _claim_value) {
2709       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2710                              "claim value = %d, should be %d",
2711                              HR_FORMAT_PARAMS(hr),
2712                              hr->claim_value(), _claim_value);
2713       _failures += 1;
2714     }
2715     return false;
2716   }
2717 };
2718 
2719 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2720   CheckClaimValuesInCSetHRClosure cl(claim_value);
2721   collection_set_iterate(&cl);
2722   return cl.failures() == 0;
2723 }
2724 #endif // ASSERT
2725 
2726 // Clear the cached CSet starting regions and (more importantly)
2727 // the time stamps. Called when we reset the GC time stamp.
2728 void G1CollectedHeap::clear_cset_start_regions() {
2729   assert(_worker_cset_start_region != NULL, "sanity");
2730   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2731 
2732   int n_queues = MAX2((int)ParallelGCThreads, 1);
2733   for (int i = 0; i < n_queues; i++) {
2734     _worker_cset_start_region[i] = NULL;
2735     _worker_cset_start_region_time_stamp[i] = 0;
2736   }
2737 }
2738 
2739 // Given the id of a worker, obtain or calculate a suitable
2740 // starting region for iterating over the current collection set.
2741 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2742   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2743 
2744   HeapRegion* result = NULL;
2745   unsigned gc_time_stamp = get_gc_time_stamp();
2746 
2747   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2748     // Cached starting region for current worker was set
2749     // during the current pause - so it's valid.
2750     // Note: the cached starting heap region may be NULL
2751     // (when the collection set is empty).
2752     result = _worker_cset_start_region[worker_i];
2753     assert(result == NULL || result->in_collection_set(), "sanity");
2754     return result;
2755   }
2756 
2757   // The cached entry was not valid so let's calculate
2758   // a suitable starting heap region for this worker.
2759 
2760   // We want the parallel threads to start their collection
2761   // set iteration at different collection set regions to
2762   // avoid contention.
2763   // If we have:
2764   //          n collection set regions
2765   //          p threads
2766   // Then thread t will start at region floor ((t * n) / p)
2767 
2768   result = g1_policy()->collection_set();
2769   if (G1CollectedHeap::use_parallel_gc_threads()) {
2770     uint cs_size = g1_policy()->cset_region_length();
2771     uint active_workers = workers()->active_workers();
2772     assert(UseDynamicNumberOfGCThreads ||
2773              active_workers == workers()->total_workers(),
2774              "Unless dynamic should use total workers");
2775 
2776     uint end_ind   = (cs_size * worker_i) / active_workers;
2777     uint start_ind = 0;
2778 
2779     if (worker_i > 0 &&
2780         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2781       // Previous workers starting region is valid
2782       // so let's iterate from there
2783       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2784       result = _worker_cset_start_region[worker_i - 1];
2785     }
2786 
2787     for (uint i = start_ind; i < end_ind; i++) {
2788       result = result->next_in_collection_set();
2789     }
2790   }
2791 
2792   // Note: the calculated starting heap region may be NULL
2793   // (when the collection set is empty).
2794   assert(result == NULL || result->in_collection_set(), "sanity");
2795   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2796          "should be updated only once per pause");
2797   _worker_cset_start_region[worker_i] = result;
2798   OrderAccess::storestore();
2799   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2800   return result;
2801 }
2802 
2803 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2804   HeapRegion* r = g1_policy()->collection_set();
2805   while (r != NULL) {
2806     HeapRegion* next = r->next_in_collection_set();
2807     if (cl->doHeapRegion(r)) {
2808       cl->incomplete();
2809       return;
2810     }
2811     r = next;
2812   }
2813 }
2814 
2815 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2816                                                   HeapRegionClosure *cl) {
2817   if (r == NULL) {
2818     // The CSet is empty so there's nothing to do.
2819     return;
2820   }
2821 
2822   assert(r->in_collection_set(),
2823          "Start region must be a member of the collection set.");
2824   HeapRegion* cur = r;
2825   while (cur != NULL) {
2826     HeapRegion* next = cur->next_in_collection_set();
2827     if (cl->doHeapRegion(cur) && false) {
2828       cl->incomplete();
2829       return;
2830     }
2831     cur = next;
2832   }
2833   cur = g1_policy()->collection_set();
2834   while (cur != r) {
2835     HeapRegion* next = cur->next_in_collection_set();
2836     if (cl->doHeapRegion(cur) && false) {
2837       cl->incomplete();
2838       return;
2839     }
2840     cur = next;
2841   }
2842 }
2843 
2844 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2845   HeapRegion* result = _hrs.next_region_in_heap(from);
2846   while (result != NULL && result->isHumongous()) {
2847     result = _hrs.next_region_in_heap(result);
2848   }
2849   return result;
2850 }
2851 
2852 Space* G1CollectedHeap::space_containing(const void* addr) const {
2853   return heap_region_containing(addr);
2854 }
2855 
2856 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2857   Space* sp = space_containing(addr);
2858   return sp->block_start(addr);
2859 }
2860 
2861 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2862   Space* sp = space_containing(addr);
2863   return sp->block_size(addr);
2864 }
2865 
2866 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2867   Space* sp = space_containing(addr);
2868   return sp->block_is_obj(addr);
2869 }
2870 
2871 bool G1CollectedHeap::supports_tlab_allocation() const {
2872   return true;
2873 }
2874 
2875 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2876   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2877 }
2878 
2879 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2880   return young_list()->eden_used_bytes();
2881 }
2882 
2883 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2884 // must be smaller than the humongous object limit.
2885 size_t G1CollectedHeap::max_tlab_size() const {
2886   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2887 }
2888 
2889 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2890   // Return the remaining space in the cur alloc region, but not less than
2891   // the min TLAB size.
2892 
2893   // Also, this value can be at most the humongous object threshold,
2894   // since we can't allow tlabs to grow big enough to accommodate
2895   // humongous objects.
2896 
2897   HeapRegion* hr = _mutator_alloc_region.get();
2898   size_t max_tlab = max_tlab_size() * wordSize;
2899   if (hr == NULL) {
2900     return max_tlab;
2901   } else {
2902     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2903   }
2904 }
2905 
2906 size_t G1CollectedHeap::max_capacity() const {
2907   return _hrs.reserved().byte_size();
2908 }
2909 
2910 jlong G1CollectedHeap::millis_since_last_gc() {
2911   // assert(false, "NYI");
2912   return 0;
2913 }
2914 
2915 void G1CollectedHeap::prepare_for_verify() {
2916   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2917     ensure_parsability(false);
2918   }
2919   g1_rem_set()->prepare_for_verify();
2920 }
2921 
2922 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2923                                               VerifyOption vo) {
2924   switch (vo) {
2925   case VerifyOption_G1UsePrevMarking:
2926     return hr->obj_allocated_since_prev_marking(obj);
2927   case VerifyOption_G1UseNextMarking:
2928     return hr->obj_allocated_since_next_marking(obj);
2929   case VerifyOption_G1UseMarkWord:
2930     return false;
2931   default:
2932     ShouldNotReachHere();
2933   }
2934   return false; // keep some compilers happy
2935 }
2936 
2937 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2938   switch (vo) {
2939   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2940   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2941   case VerifyOption_G1UseMarkWord:    return NULL;
2942   default:                            ShouldNotReachHere();
2943   }
2944   return NULL; // keep some compilers happy
2945 }
2946 
2947 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2948   switch (vo) {
2949   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2950   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2951   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2952   default:                            ShouldNotReachHere();
2953   }
2954   return false; // keep some compilers happy
2955 }
2956 
2957 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2958   switch (vo) {
2959   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2960   case VerifyOption_G1UseNextMarking: return "NTAMS";
2961   case VerifyOption_G1UseMarkWord:    return "NONE";
2962   default:                            ShouldNotReachHere();
2963   }
2964   return NULL; // keep some compilers happy
2965 }
2966 
2967 class VerifyRootsClosure: public OopClosure {
2968 private:
2969   G1CollectedHeap* _g1h;
2970   VerifyOption     _vo;
2971   bool             _failures;
2972 public:
2973   // _vo == UsePrevMarking -> use "prev" marking information,
2974   // _vo == UseNextMarking -> use "next" marking information,
2975   // _vo == UseMarkWord    -> use mark word from object header.
2976   VerifyRootsClosure(VerifyOption vo) :
2977     _g1h(G1CollectedHeap::heap()),
2978     _vo(vo),
2979     _failures(false) { }
2980 
2981   bool failures() { return _failures; }
2982 
2983   template <class T> void do_oop_nv(T* p) {
2984     T heap_oop = oopDesc::load_heap_oop(p);
2985     if (!oopDesc::is_null(heap_oop)) {
2986       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2987       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2988         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2989                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2990         if (_vo == VerifyOption_G1UseMarkWord) {
2991           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2992         }
2993         obj->print_on(gclog_or_tty);
2994         _failures = true;
2995       }
2996     }
2997   }
2998 
2999   void do_oop(oop* p)       { do_oop_nv(p); }
3000   void do_oop(narrowOop* p) { do_oop_nv(p); }
3001 };
3002 
3003 class G1VerifyCodeRootOopClosure: public OopClosure {
3004   G1CollectedHeap* _g1h;
3005   OopClosure* _root_cl;
3006   nmethod* _nm;
3007   VerifyOption _vo;
3008   bool _failures;
3009 
3010   template <class T> void do_oop_work(T* p) {
3011     // First verify that this root is live
3012     _root_cl->do_oop(p);
3013 
3014     if (!G1VerifyHeapRegionCodeRoots) {
3015       // We're not verifying the code roots attached to heap region.
3016       return;
3017     }
3018 
3019     // Don't check the code roots during marking verification in a full GC
3020     if (_vo == VerifyOption_G1UseMarkWord) {
3021       return;
3022     }
3023 
3024     // Now verify that the current nmethod (which contains p) is
3025     // in the code root list of the heap region containing the
3026     // object referenced by p.
3027 
3028     T heap_oop = oopDesc::load_heap_oop(p);
3029     if (!oopDesc::is_null(heap_oop)) {
3030       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3031 
3032       // Now fetch the region containing the object
3033       HeapRegion* hr = _g1h->heap_region_containing(obj);
3034       HeapRegionRemSet* hrrs = hr->rem_set();
3035       // Verify that the strong code root list for this region
3036       // contains the nmethod
3037       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3038         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3039                               "from nmethod "PTR_FORMAT" not in strong "
3040                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3041                               p, _nm, hr->bottom(), hr->end());
3042         _failures = true;
3043       }
3044     }
3045   }
3046 
3047 public:
3048   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3049     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3050 
3051   void do_oop(oop* p) { do_oop_work(p); }
3052   void do_oop(narrowOop* p) { do_oop_work(p); }
3053 
3054   void set_nmethod(nmethod* nm) { _nm = nm; }
3055   bool failures() { return _failures; }
3056 };
3057 
3058 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3059   G1VerifyCodeRootOopClosure* _oop_cl;
3060 
3061 public:
3062   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3063     _oop_cl(oop_cl) {}
3064 
3065   void do_code_blob(CodeBlob* cb) {
3066     nmethod* nm = cb->as_nmethod_or_null();
3067     if (nm != NULL) {
3068       _oop_cl->set_nmethod(nm);
3069       nm->oops_do(_oop_cl);
3070     }
3071   }
3072 };
3073 
3074 class YoungRefCounterClosure : public OopClosure {
3075   G1CollectedHeap* _g1h;
3076   int              _count;
3077  public:
3078   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3079   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3080   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3081 
3082   int count() { return _count; }
3083   void reset_count() { _count = 0; };
3084 };
3085 
3086 class VerifyKlassClosure: public KlassClosure {
3087   YoungRefCounterClosure _young_ref_counter_closure;
3088   OopClosure *_oop_closure;
3089  public:
3090   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3091   void do_klass(Klass* k) {
3092     k->oops_do(_oop_closure);
3093 
3094     _young_ref_counter_closure.reset_count();
3095     k->oops_do(&_young_ref_counter_closure);
3096     if (_young_ref_counter_closure.count() > 0) {
3097       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3098     }
3099   }
3100 };
3101 
3102 class VerifyLivenessOopClosure: public OopClosure {
3103   G1CollectedHeap* _g1h;
3104   VerifyOption _vo;
3105 public:
3106   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3107     _g1h(g1h), _vo(vo)
3108   { }
3109   void do_oop(narrowOop *p) { do_oop_work(p); }
3110   void do_oop(      oop *p) { do_oop_work(p); }
3111 
3112   template <class T> void do_oop_work(T *p) {
3113     oop obj = oopDesc::load_decode_heap_oop(p);
3114     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3115               "Dead object referenced by a not dead object");
3116   }
3117 };
3118 
3119 class VerifyObjsInRegionClosure: public ObjectClosure {
3120 private:
3121   G1CollectedHeap* _g1h;
3122   size_t _live_bytes;
3123   HeapRegion *_hr;
3124   VerifyOption _vo;
3125 public:
3126   // _vo == UsePrevMarking -> use "prev" marking information,
3127   // _vo == UseNextMarking -> use "next" marking information,
3128   // _vo == UseMarkWord    -> use mark word from object header.
3129   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3130     : _live_bytes(0), _hr(hr), _vo(vo) {
3131     _g1h = G1CollectedHeap::heap();
3132   }
3133   void do_object(oop o) {
3134     VerifyLivenessOopClosure isLive(_g1h, _vo);
3135     assert(o != NULL, "Huh?");
3136     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3137       // If the object is alive according to the mark word,
3138       // then verify that the marking information agrees.
3139       // Note we can't verify the contra-positive of the
3140       // above: if the object is dead (according to the mark
3141       // word), it may not be marked, or may have been marked
3142       // but has since became dead, or may have been allocated
3143       // since the last marking.
3144       if (_vo == VerifyOption_G1UseMarkWord) {
3145         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3146       }
3147 
3148       o->oop_iterate_no_header(&isLive);
3149       if (!_hr->obj_allocated_since_prev_marking(o)) {
3150         size_t obj_size = o->size();    // Make sure we don't overflow
3151         _live_bytes += (obj_size * HeapWordSize);
3152       }
3153     }
3154   }
3155   size_t live_bytes() { return _live_bytes; }
3156 };
3157 
3158 class PrintObjsInRegionClosure : public ObjectClosure {
3159   HeapRegion *_hr;
3160   G1CollectedHeap *_g1;
3161 public:
3162   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3163     _g1 = G1CollectedHeap::heap();
3164   };
3165 
3166   void do_object(oop o) {
3167     if (o != NULL) {
3168       HeapWord *start = (HeapWord *) o;
3169       size_t word_sz = o->size();
3170       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3171                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3172                           (void*) o, word_sz,
3173                           _g1->isMarkedPrev(o),
3174                           _g1->isMarkedNext(o),
3175                           _hr->obj_allocated_since_prev_marking(o));
3176       HeapWord *end = start + word_sz;
3177       HeapWord *cur;
3178       int *val;
3179       for (cur = start; cur < end; cur++) {
3180         val = (int *) cur;
3181         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3182       }
3183     }
3184   }
3185 };
3186 
3187 class VerifyRegionClosure: public HeapRegionClosure {
3188 private:
3189   bool             _par;
3190   VerifyOption     _vo;
3191   bool             _failures;
3192 public:
3193   // _vo == UsePrevMarking -> use "prev" marking information,
3194   // _vo == UseNextMarking -> use "next" marking information,
3195   // _vo == UseMarkWord    -> use mark word from object header.
3196   VerifyRegionClosure(bool par, VerifyOption vo)
3197     : _par(par),
3198       _vo(vo),
3199       _failures(false) {}
3200 
3201   bool failures() {
3202     return _failures;
3203   }
3204 
3205   bool doHeapRegion(HeapRegion* r) {
3206     if (!r->continuesHumongous()) {
3207       bool failures = false;
3208       r->verify(_vo, &failures);
3209       if (failures) {
3210         _failures = true;
3211       } else {
3212         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3213         r->object_iterate(&not_dead_yet_cl);
3214         if (_vo != VerifyOption_G1UseNextMarking) {
3215           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3216             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3217                                    "max_live_bytes "SIZE_FORMAT" "
3218                                    "< calculated "SIZE_FORMAT,
3219                                    r->bottom(), r->end(),
3220                                    r->max_live_bytes(),
3221                                  not_dead_yet_cl.live_bytes());
3222             _failures = true;
3223           }
3224         } else {
3225           // When vo == UseNextMarking we cannot currently do a sanity
3226           // check on the live bytes as the calculation has not been
3227           // finalized yet.
3228         }
3229       }
3230     }
3231     return false; // stop the region iteration if we hit a failure
3232   }
3233 };
3234 
3235 // This is the task used for parallel verification of the heap regions
3236 
3237 class G1ParVerifyTask: public AbstractGangTask {
3238 private:
3239   G1CollectedHeap* _g1h;
3240   VerifyOption     _vo;
3241   bool             _failures;
3242 
3243 public:
3244   // _vo == UsePrevMarking -> use "prev" marking information,
3245   // _vo == UseNextMarking -> use "next" marking information,
3246   // _vo == UseMarkWord    -> use mark word from object header.
3247   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3248     AbstractGangTask("Parallel verify task"),
3249     _g1h(g1h),
3250     _vo(vo),
3251     _failures(false) { }
3252 
3253   bool failures() {
3254     return _failures;
3255   }
3256 
3257   void work(uint worker_id) {
3258     HandleMark hm;
3259     VerifyRegionClosure blk(true, _vo);
3260     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3261                                           _g1h->workers()->active_workers(),
3262                                           HeapRegion::ParVerifyClaimValue);
3263     if (blk.failures()) {
3264       _failures = true;
3265     }
3266   }
3267 };
3268 
3269 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3270   if (SafepointSynchronize::is_at_safepoint()) {
3271     assert(Thread::current()->is_VM_thread(),
3272            "Expected to be executed serially by the VM thread at this point");
3273 
3274     if (!silent) { gclog_or_tty->print("Roots "); }
3275     VerifyRootsClosure rootsCl(vo);
3276     VerifyKlassClosure klassCl(this, &rootsCl);
3277     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3278 
3279     // We apply the relevant closures to all the oops in the
3280     // system dictionary, class loader data graph, the string table
3281     // and the nmethods in the code cache.
3282     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3283     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3284 
3285     process_all_roots(true,            // activate StrongRootsScope
3286                       SO_AllCodeCache, // roots scanning options
3287                       &rootsCl,
3288                       &cldCl,
3289                       &blobsCl);
3290 
3291     bool failures = rootsCl.failures() || codeRootsCl.failures();
3292 
3293     if (vo != VerifyOption_G1UseMarkWord) {
3294       // If we're verifying during a full GC then the region sets
3295       // will have been torn down at the start of the GC. Therefore
3296       // verifying the region sets will fail. So we only verify
3297       // the region sets when not in a full GC.
3298       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3299       verify_region_sets();
3300     }
3301 
3302     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3303     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3304       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3305              "sanity check");
3306 
3307       G1ParVerifyTask task(this, vo);
3308       assert(UseDynamicNumberOfGCThreads ||
3309         workers()->active_workers() == workers()->total_workers(),
3310         "If not dynamic should be using all the workers");
3311       int n_workers = workers()->active_workers();
3312       set_par_threads(n_workers);
3313       workers()->run_task(&task);
3314       set_par_threads(0);
3315       if (task.failures()) {
3316         failures = true;
3317       }
3318 
3319       // Checks that the expected amount of parallel work was done.
3320       // The implication is that n_workers is > 0.
3321       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3322              "sanity check");
3323 
3324       reset_heap_region_claim_values();
3325 
3326       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3327              "sanity check");
3328     } else {
3329       VerifyRegionClosure blk(false, vo);
3330       heap_region_iterate(&blk);
3331       if (blk.failures()) {
3332         failures = true;
3333       }
3334     }
3335     if (!silent) gclog_or_tty->print("RemSet ");
3336     rem_set()->verify();
3337 
3338     if (G1StringDedup::is_enabled()) {
3339       if (!silent) gclog_or_tty->print("StrDedup ");
3340       G1StringDedup::verify();
3341     }
3342 
3343     if (failures) {
3344       gclog_or_tty->print_cr("Heap:");
3345       // It helps to have the per-region information in the output to
3346       // help us track down what went wrong. This is why we call
3347       // print_extended_on() instead of print_on().
3348       print_extended_on(gclog_or_tty);
3349       gclog_or_tty->cr();
3350 #ifndef PRODUCT
3351       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3352         concurrent_mark()->print_reachable("at-verification-failure",
3353                                            vo, false /* all */);
3354       }
3355 #endif
3356       gclog_or_tty->flush();
3357     }
3358     guarantee(!failures, "there should not have been any failures");
3359   } else {
3360     if (!silent) {
3361       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3362       if (G1StringDedup::is_enabled()) {
3363         gclog_or_tty->print(", StrDedup");
3364       }
3365       gclog_or_tty->print(") ");
3366     }
3367   }
3368 }
3369 
3370 void G1CollectedHeap::verify(bool silent) {
3371   verify(silent, VerifyOption_G1UsePrevMarking);
3372 }
3373 
3374 double G1CollectedHeap::verify(bool guard, const char* msg) {
3375   double verify_time_ms = 0.0;
3376 
3377   if (guard && total_collections() >= VerifyGCStartAt) {
3378     double verify_start = os::elapsedTime();
3379     HandleMark hm;  // Discard invalid handles created during verification
3380     prepare_for_verify();
3381     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3382     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3383   }
3384 
3385   return verify_time_ms;
3386 }
3387 
3388 void G1CollectedHeap::verify_before_gc() {
3389   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3390   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3391 }
3392 
3393 void G1CollectedHeap::verify_after_gc() {
3394   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3395   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3396 }
3397 
3398 class PrintRegionClosure: public HeapRegionClosure {
3399   outputStream* _st;
3400 public:
3401   PrintRegionClosure(outputStream* st) : _st(st) {}
3402   bool doHeapRegion(HeapRegion* r) {
3403     r->print_on(_st);
3404     return false;
3405   }
3406 };
3407 
3408 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3409                                        const HeapRegion* hr,
3410                                        const VerifyOption vo) const {
3411   switch (vo) {
3412   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3413   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3414   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3415   default:                            ShouldNotReachHere();
3416   }
3417   return false; // keep some compilers happy
3418 }
3419 
3420 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3421                                        const VerifyOption vo) const {
3422   switch (vo) {
3423   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3424   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3425   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3426   default:                            ShouldNotReachHere();
3427   }
3428   return false; // keep some compilers happy
3429 }
3430 
3431 void G1CollectedHeap::print_on(outputStream* st) const {
3432   st->print(" %-20s", "garbage-first heap");
3433   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3434             capacity()/K, used_unlocked()/K);
3435   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3436             _hrs.reserved().start(),
3437             _hrs.reserved().start() + _hrs.length() + HeapRegion::GrainWords,
3438             _hrs.reserved().end());
3439   st->cr();
3440   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3441   uint young_regions = _young_list->length();
3442   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3443             (size_t) young_regions * HeapRegion::GrainBytes / K);
3444   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3445   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3446             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3447   st->cr();
3448   MetaspaceAux::print_on(st);
3449 }
3450 
3451 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3452   print_on(st);
3453 
3454   // Print the per-region information.
3455   st->cr();
3456   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3457                "HS=humongous(starts), HC=humongous(continues), "
3458                "CS=collection set, F=free, TS=gc time stamp, "
3459                "PTAMS=previous top-at-mark-start, "
3460                "NTAMS=next top-at-mark-start)");
3461   PrintRegionClosure blk(st);
3462   heap_region_iterate(&blk);
3463 }
3464 
3465 void G1CollectedHeap::print_on_error(outputStream* st) const {
3466   this->CollectedHeap::print_on_error(st);
3467 
3468   if (_cm != NULL) {
3469     st->cr();
3470     _cm->print_on_error(st);
3471   }
3472 }
3473 
3474 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3475   if (G1CollectedHeap::use_parallel_gc_threads()) {
3476     workers()->print_worker_threads_on(st);
3477   }
3478   _cmThread->print_on(st);
3479   st->cr();
3480   _cm->print_worker_threads_on(st);
3481   _cg1r->print_worker_threads_on(st);
3482   if (G1StringDedup::is_enabled()) {
3483     G1StringDedup::print_worker_threads_on(st);
3484   }
3485 }
3486 
3487 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3488   if (G1CollectedHeap::use_parallel_gc_threads()) {
3489     workers()->threads_do(tc);
3490   }
3491   tc->do_thread(_cmThread);
3492   _cg1r->threads_do(tc);
3493   if (G1StringDedup::is_enabled()) {
3494     G1StringDedup::threads_do(tc);
3495   }
3496 }
3497 
3498 void G1CollectedHeap::print_tracing_info() const {
3499   // We'll overload this to mean "trace GC pause statistics."
3500   if (TraceGen0Time || TraceGen1Time) {
3501     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3502     // to that.
3503     g1_policy()->print_tracing_info();
3504   }
3505   if (G1SummarizeRSetStats) {
3506     g1_rem_set()->print_summary_info();
3507   }
3508   if (G1SummarizeConcMark) {
3509     concurrent_mark()->print_summary_info();
3510   }
3511   g1_policy()->print_yg_surv_rate_info();
3512   SpecializationStats::print();
3513 }
3514 
3515 #ifndef PRODUCT
3516 // Helpful for debugging RSet issues.
3517 
3518 class PrintRSetsClosure : public HeapRegionClosure {
3519 private:
3520   const char* _msg;
3521   size_t _occupied_sum;
3522 
3523 public:
3524   bool doHeapRegion(HeapRegion* r) {
3525     HeapRegionRemSet* hrrs = r->rem_set();
3526     size_t occupied = hrrs->occupied();
3527     _occupied_sum += occupied;
3528 
3529     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3530                            HR_FORMAT_PARAMS(r));
3531     if (occupied == 0) {
3532       gclog_or_tty->print_cr("  RSet is empty");
3533     } else {
3534       hrrs->print();
3535     }
3536     gclog_or_tty->print_cr("----------");
3537     return false;
3538   }
3539 
3540   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3541     gclog_or_tty->cr();
3542     gclog_or_tty->print_cr("========================================");
3543     gclog_or_tty->print_cr("%s", msg);
3544     gclog_or_tty->cr();
3545   }
3546 
3547   ~PrintRSetsClosure() {
3548     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3549     gclog_or_tty->print_cr("========================================");
3550     gclog_or_tty->cr();
3551   }
3552 };
3553 
3554 void G1CollectedHeap::print_cset_rsets() {
3555   PrintRSetsClosure cl("Printing CSet RSets");
3556   collection_set_iterate(&cl);
3557 }
3558 
3559 void G1CollectedHeap::print_all_rsets() {
3560   PrintRSetsClosure cl("Printing All RSets");;
3561   heap_region_iterate(&cl);
3562 }
3563 #endif // PRODUCT
3564 
3565 G1CollectedHeap* G1CollectedHeap::heap() {
3566   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3567          "not a garbage-first heap");
3568   return _g1h;
3569 }
3570 
3571 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3572   // always_do_update_barrier = false;
3573   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3574   // Fill TLAB's and such
3575   accumulate_statistics_all_tlabs();
3576   ensure_parsability(true);
3577 
3578   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3579       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3580     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3581   }
3582 }
3583 
3584 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3585 
3586   if (G1SummarizeRSetStats &&
3587       (G1SummarizeRSetStatsPeriod > 0) &&
3588       // we are at the end of the GC. Total collections has already been increased.
3589       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3590     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3591   }
3592 
3593   // FIXME: what is this about?
3594   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3595   // is set.
3596   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3597                         "derived pointer present"));
3598   // always_do_update_barrier = true;
3599 
3600   resize_all_tlabs();
3601 
3602   // We have just completed a GC. Update the soft reference
3603   // policy with the new heap occupancy
3604   Universe::update_heap_info_at_gc();
3605 }
3606 
3607 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3608                                                unsigned int gc_count_before,
3609                                                bool* succeeded,
3610                                                GCCause::Cause gc_cause) {
3611   assert_heap_not_locked_and_not_at_safepoint();
3612   g1_policy()->record_stop_world_start();
3613   VM_G1IncCollectionPause op(gc_count_before,
3614                              word_size,
3615                              false, /* should_initiate_conc_mark */
3616                              g1_policy()->max_pause_time_ms(),
3617                              gc_cause);
3618   VMThread::execute(&op);
3619 
3620   HeapWord* result = op.result();
3621   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3622   assert(result == NULL || ret_succeeded,
3623          "the result should be NULL if the VM did not succeed");
3624   *succeeded = ret_succeeded;
3625 
3626   assert_heap_not_locked();
3627   return result;
3628 }
3629 
3630 void
3631 G1CollectedHeap::doConcurrentMark() {
3632   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3633   if (!_cmThread->in_progress()) {
3634     _cmThread->set_started();
3635     CGC_lock->notify();
3636   }
3637 }
3638 
3639 size_t G1CollectedHeap::pending_card_num() {
3640   size_t extra_cards = 0;
3641   JavaThread *curr = Threads::first();
3642   while (curr != NULL) {
3643     DirtyCardQueue& dcq = curr->dirty_card_queue();
3644     extra_cards += dcq.size();
3645     curr = curr->next();
3646   }
3647   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3648   size_t buffer_size = dcqs.buffer_size();
3649   size_t buffer_num = dcqs.completed_buffers_num();
3650 
3651   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3652   // in bytes - not the number of 'entries'. We need to convert
3653   // into a number of cards.
3654   return (buffer_size * buffer_num + extra_cards) / oopSize;
3655 }
3656 
3657 size_t G1CollectedHeap::cards_scanned() {
3658   return g1_rem_set()->cardsScanned();
3659 }
3660 
3661 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3662   HeapRegion* region = region_at(index);
3663   assert(region->startsHumongous(), "Must start a humongous object");
3664   return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3665 }
3666 
3667 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3668  private:
3669   size_t _total_humongous;
3670   size_t _candidate_humongous;
3671  public:
3672   RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3673   }
3674 
3675   virtual bool doHeapRegion(HeapRegion* r) {
3676     if (!r->startsHumongous()) {
3677       return false;
3678     }
3679     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3680 
3681     uint region_idx = r->hrs_index();
3682     bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3683     // Is_candidate already filters out humongous regions with some remembered set.
3684     // This will not lead to humongous object that we mistakenly keep alive because
3685     // during young collection the remembered sets will only be added to.
3686     if (is_candidate) {
3687       g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3688       _candidate_humongous++;
3689     }
3690     _total_humongous++;
3691 
3692     return false;
3693   }
3694 
3695   size_t total_humongous() const { return _total_humongous; }
3696   size_t candidate_humongous() const { return _candidate_humongous; }
3697 };
3698 
3699 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3700   if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3701     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3702     return;
3703   }
3704 
3705   RegisterHumongousWithInCSetFastTestClosure cl;
3706   heap_region_iterate(&cl);
3707   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3708                                                                   cl.candidate_humongous());
3709   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3710 
3711   if (_has_humongous_reclaim_candidates) {
3712     clear_humongous_is_live_table();
3713   }
3714 }
3715 
3716 void
3717 G1CollectedHeap::setup_surviving_young_words() {
3718   assert(_surviving_young_words == NULL, "pre-condition");
3719   uint array_length = g1_policy()->young_cset_region_length();
3720   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3721   if (_surviving_young_words == NULL) {
3722     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3723                           "Not enough space for young surv words summary.");
3724   }
3725   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3726 #ifdef ASSERT
3727   for (uint i = 0;  i < array_length; ++i) {
3728     assert( _surviving_young_words[i] == 0, "memset above" );
3729   }
3730 #endif // !ASSERT
3731 }
3732 
3733 void
3734 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3735   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3736   uint array_length = g1_policy()->young_cset_region_length();
3737   for (uint i = 0; i < array_length; ++i) {
3738     _surviving_young_words[i] += surv_young_words[i];
3739   }
3740 }
3741 
3742 void
3743 G1CollectedHeap::cleanup_surviving_young_words() {
3744   guarantee( _surviving_young_words != NULL, "pre-condition" );
3745   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3746   _surviving_young_words = NULL;
3747 }
3748 
3749 #ifdef ASSERT
3750 class VerifyCSetClosure: public HeapRegionClosure {
3751 public:
3752   bool doHeapRegion(HeapRegion* hr) {
3753     // Here we check that the CSet region's RSet is ready for parallel
3754     // iteration. The fields that we'll verify are only manipulated
3755     // when the region is part of a CSet and is collected. Afterwards,
3756     // we reset these fields when we clear the region's RSet (when the
3757     // region is freed) so they are ready when the region is
3758     // re-allocated. The only exception to this is if there's an
3759     // evacuation failure and instead of freeing the region we leave
3760     // it in the heap. In that case, we reset these fields during
3761     // evacuation failure handling.
3762     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3763 
3764     // Here's a good place to add any other checks we'd like to
3765     // perform on CSet regions.
3766     return false;
3767   }
3768 };
3769 #endif // ASSERT
3770 
3771 #if TASKQUEUE_STATS
3772 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3773   st->print_raw_cr("GC Task Stats");
3774   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3775   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3776 }
3777 
3778 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3779   print_taskqueue_stats_hdr(st);
3780 
3781   TaskQueueStats totals;
3782   const int n = workers() != NULL ? workers()->total_workers() : 1;
3783   for (int i = 0; i < n; ++i) {
3784     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3785     totals += task_queue(i)->stats;
3786   }
3787   st->print_raw("tot "); totals.print(st); st->cr();
3788 
3789   DEBUG_ONLY(totals.verify());
3790 }
3791 
3792 void G1CollectedHeap::reset_taskqueue_stats() {
3793   const int n = workers() != NULL ? workers()->total_workers() : 1;
3794   for (int i = 0; i < n; ++i) {
3795     task_queue(i)->stats.reset();
3796   }
3797 }
3798 #endif // TASKQUEUE_STATS
3799 
3800 void G1CollectedHeap::log_gc_header() {
3801   if (!G1Log::fine()) {
3802     return;
3803   }
3804 
3805   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3806 
3807   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3808     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3809     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3810 
3811   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3812 }
3813 
3814 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3815   if (!G1Log::fine()) {
3816     return;
3817   }
3818 
3819   if (G1Log::finer()) {
3820     if (evacuation_failed()) {
3821       gclog_or_tty->print(" (to-space exhausted)");
3822     }
3823     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3824     g1_policy()->phase_times()->note_gc_end();
3825     g1_policy()->phase_times()->print(pause_time_sec);
3826     g1_policy()->print_detailed_heap_transition();
3827   } else {
3828     if (evacuation_failed()) {
3829       gclog_or_tty->print("--");
3830     }
3831     g1_policy()->print_heap_transition();
3832     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3833   }
3834   gclog_or_tty->flush();
3835 }
3836 
3837 bool
3838 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3839   assert_at_safepoint(true /* should_be_vm_thread */);
3840   guarantee(!is_gc_active(), "collection is not reentrant");
3841 
3842   if (GC_locker::check_active_before_gc()) {
3843     return false;
3844   }
3845 
3846   _gc_timer_stw->register_gc_start();
3847 
3848   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3849 
3850   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3851   ResourceMark rm;
3852 
3853   print_heap_before_gc();
3854   trace_heap_before_gc(_gc_tracer_stw);
3855 
3856   verify_region_sets_optional();
3857   verify_dirty_young_regions();
3858 
3859   // This call will decide whether this pause is an initial-mark
3860   // pause. If it is, during_initial_mark_pause() will return true
3861   // for the duration of this pause.
3862   g1_policy()->decide_on_conc_mark_initiation();
3863 
3864   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3865   assert(!g1_policy()->during_initial_mark_pause() ||
3866           g1_policy()->gcs_are_young(), "sanity");
3867 
3868   // We also do not allow mixed GCs during marking.
3869   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3870 
3871   // Record whether this pause is an initial mark. When the current
3872   // thread has completed its logging output and it's safe to signal
3873   // the CM thread, the flag's value in the policy has been reset.
3874   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3875 
3876   // Inner scope for scope based logging, timers, and stats collection
3877   {
3878     EvacuationInfo evacuation_info;
3879 
3880     if (g1_policy()->during_initial_mark_pause()) {
3881       // We are about to start a marking cycle, so we increment the
3882       // full collection counter.
3883       increment_old_marking_cycles_started();
3884       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3885     }
3886 
3887     _gc_tracer_stw->report_yc_type(yc_type());
3888 
3889     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3890 
3891     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3892                                 workers()->active_workers() : 1);
3893     double pause_start_sec = os::elapsedTime();
3894     g1_policy()->phase_times()->note_gc_start(active_workers);
3895     log_gc_header();
3896 
3897     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3898     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3899 
3900     // If the secondary_free_list is not empty, append it to the
3901     // free_list. No need to wait for the cleanup operation to finish;
3902     // the region allocation code will check the secondary_free_list
3903     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3904     // set, skip this step so that the region allocation code has to
3905     // get entries from the secondary_free_list.
3906     if (!G1StressConcRegionFreeing) {
3907       append_secondary_free_list_if_not_empty_with_lock();
3908     }
3909 
3910     assert(check_young_list_well_formed(), "young list should be well formed");
3911     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3912            "sanity check");
3913 
3914     // Don't dynamically change the number of GC threads this early.  A value of
3915     // 0 is used to indicate serial work.  When parallel work is done,
3916     // it will be set.
3917 
3918     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3919       IsGCActiveMark x;
3920 
3921       gc_prologue(false);
3922       increment_total_collections(false /* full gc */);
3923       increment_gc_time_stamp();
3924 
3925       verify_before_gc();
3926       check_bitmaps("GC Start");
3927 
3928       COMPILER2_PRESENT(DerivedPointerTable::clear());
3929 
3930       // Please see comment in g1CollectedHeap.hpp and
3931       // G1CollectedHeap::ref_processing_init() to see how
3932       // reference processing currently works in G1.
3933 
3934       // Enable discovery in the STW reference processor
3935       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3936                                             true /*verify_no_refs*/);
3937 
3938       {
3939         // We want to temporarily turn off discovery by the
3940         // CM ref processor, if necessary, and turn it back on
3941         // on again later if we do. Using a scoped
3942         // NoRefDiscovery object will do this.
3943         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3944 
3945         // Forget the current alloc region (we might even choose it to be part
3946         // of the collection set!).
3947         release_mutator_alloc_region();
3948 
3949         // We should call this after we retire the mutator alloc
3950         // region(s) so that all the ALLOC / RETIRE events are generated
3951         // before the start GC event.
3952         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3953 
3954         // This timing is only used by the ergonomics to handle our pause target.
3955         // It is unclear why this should not include the full pause. We will
3956         // investigate this in CR 7178365.
3957         //
3958         // Preserving the old comment here if that helps the investigation:
3959         //
3960         // The elapsed time induced by the start time below deliberately elides
3961         // the possible verification above.
3962         double sample_start_time_sec = os::elapsedTime();
3963 
3964 #if YOUNG_LIST_VERBOSE
3965         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3966         _young_list->print();
3967         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3968 #endif // YOUNG_LIST_VERBOSE
3969 
3970         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3971 
3972         double scan_wait_start = os::elapsedTime();
3973         // We have to wait until the CM threads finish scanning the
3974         // root regions as it's the only way to ensure that all the
3975         // objects on them have been correctly scanned before we start
3976         // moving them during the GC.
3977         bool waited = _cm->root_regions()->wait_until_scan_finished();
3978         double wait_time_ms = 0.0;
3979         if (waited) {
3980           double scan_wait_end = os::elapsedTime();
3981           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3982         }
3983         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3984 
3985 #if YOUNG_LIST_VERBOSE
3986         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3987         _young_list->print();
3988 #endif // YOUNG_LIST_VERBOSE
3989 
3990         if (g1_policy()->during_initial_mark_pause()) {
3991           concurrent_mark()->checkpointRootsInitialPre();
3992         }
3993 
3994 #if YOUNG_LIST_VERBOSE
3995         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3996         _young_list->print();
3997         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3998 #endif // YOUNG_LIST_VERBOSE
3999 
4000         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4001 
4002         register_humongous_regions_with_in_cset_fast_test();
4003 
4004         _cm->note_start_of_gc();
4005         // We should not verify the per-thread SATB buffers given that
4006         // we have not filtered them yet (we'll do so during the
4007         // GC). We also call this after finalize_cset() to
4008         // ensure that the CSet has been finalized.
4009         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4010                                  true  /* verify_enqueued_buffers */,
4011                                  false /* verify_thread_buffers */,
4012                                  true  /* verify_fingers */);
4013 
4014         if (_hr_printer.is_active()) {
4015           HeapRegion* hr = g1_policy()->collection_set();
4016           while (hr != NULL) {
4017             G1HRPrinter::RegionType type;
4018             if (!hr->is_young()) {
4019               type = G1HRPrinter::Old;
4020             } else if (hr->is_survivor()) {
4021               type = G1HRPrinter::Survivor;
4022             } else {
4023               type = G1HRPrinter::Eden;
4024             }
4025             _hr_printer.cset(hr);
4026             hr = hr->next_in_collection_set();
4027           }
4028         }
4029 
4030 #ifdef ASSERT
4031         VerifyCSetClosure cl;
4032         collection_set_iterate(&cl);
4033 #endif // ASSERT
4034 
4035         setup_surviving_young_words();
4036 
4037         // Initialize the GC alloc regions.
4038         init_gc_alloc_regions(evacuation_info);
4039 
4040         // Actually do the work...
4041         evacuate_collection_set(evacuation_info);
4042 
4043         // We do this to mainly verify the per-thread SATB buffers
4044         // (which have been filtered by now) since we didn't verify
4045         // them earlier. No point in re-checking the stacks / enqueued
4046         // buffers given that the CSet has not changed since last time
4047         // we checked.
4048         _cm->verify_no_cset_oops(false /* verify_stacks */,
4049                                  false /* verify_enqueued_buffers */,
4050                                  true  /* verify_thread_buffers */,
4051                                  true  /* verify_fingers */);
4052 
4053         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4054 
4055         eagerly_reclaim_humongous_regions();
4056 
4057         g1_policy()->clear_collection_set();
4058 
4059         cleanup_surviving_young_words();
4060 
4061         // Start a new incremental collection set for the next pause.
4062         g1_policy()->start_incremental_cset_building();
4063 
4064         clear_cset_fast_test();
4065 
4066         _young_list->reset_sampled_info();
4067 
4068         // Don't check the whole heap at this point as the
4069         // GC alloc regions from this pause have been tagged
4070         // as survivors and moved on to the survivor list.
4071         // Survivor regions will fail the !is_young() check.
4072         assert(check_young_list_empty(false /* check_heap */),
4073           "young list should be empty");
4074 
4075 #if YOUNG_LIST_VERBOSE
4076         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4077         _young_list->print();
4078 #endif // YOUNG_LIST_VERBOSE
4079 
4080         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4081                                              _young_list->first_survivor_region(),
4082                                              _young_list->last_survivor_region());
4083 
4084         _young_list->reset_auxilary_lists();
4085 
4086         if (evacuation_failed()) {
4087           _summary_bytes_used = recalculate_used();
4088           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4089           for (uint i = 0; i < n_queues; i++) {
4090             if (_evacuation_failed_info_array[i].has_failed()) {
4091               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4092             }
4093           }
4094         } else {
4095           // The "used" of the the collection set have already been subtracted
4096           // when they were freed.  Add in the bytes evacuated.
4097           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4098         }
4099 
4100         if (g1_policy()->during_initial_mark_pause()) {
4101           // We have to do this before we notify the CM threads that
4102           // they can start working to make sure that all the
4103           // appropriate initialization is done on the CM object.
4104           concurrent_mark()->checkpointRootsInitialPost();
4105           set_marking_started();
4106           // Note that we don't actually trigger the CM thread at
4107           // this point. We do that later when we're sure that
4108           // the current thread has completed its logging output.
4109         }
4110 
4111         allocate_dummy_regions();
4112 
4113 #if YOUNG_LIST_VERBOSE
4114         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4115         _young_list->print();
4116         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4117 #endif // YOUNG_LIST_VERBOSE
4118 
4119         init_mutator_alloc_region();
4120 
4121         {
4122           size_t expand_bytes = g1_policy()->expansion_amount();
4123           if (expand_bytes > 0) {
4124             size_t bytes_before = capacity();
4125             // No need for an ergo verbose message here,
4126             // expansion_amount() does this when it returns a value > 0.
4127             if (!expand(expand_bytes)) {
4128               // We failed to expand the heap. Cannot do anything about it.
4129             }
4130           }
4131         }
4132 
4133         // We redo the verification but now wrt to the new CSet which
4134         // has just got initialized after the previous CSet was freed.
4135         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4136                                  true  /* verify_enqueued_buffers */,
4137                                  true  /* verify_thread_buffers */,
4138                                  true  /* verify_fingers */);
4139         _cm->note_end_of_gc();
4140 
4141         // This timing is only used by the ergonomics to handle our pause target.
4142         // It is unclear why this should not include the full pause. We will
4143         // investigate this in CR 7178365.
4144         double sample_end_time_sec = os::elapsedTime();
4145         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4146         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4147 
4148         MemoryService::track_memory_usage();
4149 
4150         // In prepare_for_verify() below we'll need to scan the deferred
4151         // update buffers to bring the RSets up-to-date if
4152         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4153         // the update buffers we'll probably need to scan cards on the
4154         // regions we just allocated to (i.e., the GC alloc
4155         // regions). However, during the last GC we called
4156         // set_saved_mark() on all the GC alloc regions, so card
4157         // scanning might skip the [saved_mark_word()...top()] area of
4158         // those regions (i.e., the area we allocated objects into
4159         // during the last GC). But it shouldn't. Given that
4160         // saved_mark_word() is conditional on whether the GC time stamp
4161         // on the region is current or not, by incrementing the GC time
4162         // stamp here we invalidate all the GC time stamps on all the
4163         // regions and saved_mark_word() will simply return top() for
4164         // all the regions. This is a nicer way of ensuring this rather
4165         // than iterating over the regions and fixing them. In fact, the
4166         // GC time stamp increment here also ensures that
4167         // saved_mark_word() will return top() between pauses, i.e.,
4168         // during concurrent refinement. So we don't need the
4169         // is_gc_active() check to decided which top to use when
4170         // scanning cards (see CR 7039627).
4171         increment_gc_time_stamp();
4172 
4173         verify_after_gc();
4174         check_bitmaps("GC End");
4175 
4176         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4177         ref_processor_stw()->verify_no_references_recorded();
4178 
4179         // CM reference discovery will be re-enabled if necessary.
4180       }
4181 
4182       // We should do this after we potentially expand the heap so
4183       // that all the COMMIT events are generated before the end GC
4184       // event, and after we retire the GC alloc regions so that all
4185       // RETIRE events are generated before the end GC event.
4186       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4187 
4188 #ifdef TRACESPINNING
4189       ParallelTaskTerminator::print_termination_counts();
4190 #endif
4191 
4192       gc_epilogue(false);
4193     }
4194 
4195     // Print the remainder of the GC log output.
4196     log_gc_footer(os::elapsedTime() - pause_start_sec);
4197 
4198     // It is not yet to safe to tell the concurrent mark to
4199     // start as we have some optional output below. We don't want the
4200     // output from the concurrent mark thread interfering with this
4201     // logging output either.
4202 
4203     _hrs.verify_optional();
4204     verify_region_sets_optional();
4205 
4206     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4207     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4208 
4209     print_heap_after_gc();
4210     trace_heap_after_gc(_gc_tracer_stw);
4211 
4212     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4213     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4214     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4215     // before any GC notifications are raised.
4216     g1mm()->update_sizes();
4217 
4218     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4219     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4220     _gc_timer_stw->register_gc_end();
4221     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4222   }
4223   // It should now be safe to tell the concurrent mark thread to start
4224   // without its logging output interfering with the logging output
4225   // that came from the pause.
4226 
4227   if (should_start_conc_mark) {
4228     // CAUTION: after the doConcurrentMark() call below,
4229     // the concurrent marking thread(s) could be running
4230     // concurrently with us. Make sure that anything after
4231     // this point does not assume that we are the only GC thread
4232     // running. Note: of course, the actual marking work will
4233     // not start until the safepoint itself is released in
4234     // SuspendibleThreadSet::desynchronize().
4235     doConcurrentMark();
4236   }
4237 
4238   return true;
4239 }
4240 
4241 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4242 {
4243   size_t gclab_word_size;
4244   switch (purpose) {
4245     case GCAllocForSurvived:
4246       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4247       break;
4248     case GCAllocForTenured:
4249       gclab_word_size = _old_plab_stats.desired_plab_sz();
4250       break;
4251     default:
4252       assert(false, "unknown GCAllocPurpose");
4253       gclab_word_size = _old_plab_stats.desired_plab_sz();
4254       break;
4255   }
4256 
4257   // Prevent humongous PLAB sizes for two reasons:
4258   // * PLABs are allocated using a similar paths as oops, but should
4259   //   never be in a humongous region
4260   // * Allowing humongous PLABs needlessly churns the region free lists
4261   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4262 }
4263 
4264 void G1CollectedHeap::init_mutator_alloc_region() {
4265   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4266   _mutator_alloc_region.init();
4267 }
4268 
4269 void G1CollectedHeap::release_mutator_alloc_region() {
4270   _mutator_alloc_region.release();
4271   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4272 }
4273 
4274 void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) {
4275   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4276   _retained_old_gc_alloc_region = NULL;
4277 
4278   // We will discard the current GC alloc region if:
4279   // a) it's in the collection set (it can happen!),
4280   // b) it's already full (no point in using it),
4281   // c) it's empty (this means that it was emptied during
4282   // a cleanup and it should be on the free list now), or
4283   // d) it's humongous (this means that it was emptied
4284   // during a cleanup and was added to the free list, but
4285   // has been subsequently used to allocate a humongous
4286   // object that may be less than the region size).
4287   if (retained_region != NULL &&
4288       !retained_region->in_collection_set() &&
4289       !(retained_region->top() == retained_region->end()) &&
4290       !retained_region->is_empty() &&
4291       !retained_region->isHumongous()) {
4292     retained_region->record_top_and_timestamp();
4293     // The retained region was added to the old region set when it was
4294     // retired. We have to remove it now, since we don't allow regions
4295     // we allocate to in the region sets. We'll re-add it later, when
4296     // it's retired again.
4297     _old_set.remove(retained_region);
4298     bool during_im = g1_policy()->during_initial_mark_pause();
4299     retained_region->note_start_of_copying(during_im);
4300     _old_gc_alloc_region.set(retained_region);
4301     _hr_printer.reuse(retained_region);
4302     evacuation_info.set_alloc_regions_used_before(retained_region->used());
4303   }
4304 }
4305 
4306 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4307   assert_at_safepoint(true /* should_be_vm_thread */);
4308 
4309   _survivor_gc_alloc_region.init();
4310   _old_gc_alloc_region.init();
4311 
4312   use_retained_old_gc_alloc_region(evacuation_info);
4313 }
4314 
4315 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4316   evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4317                                          _old_gc_alloc_region.count());
4318   _survivor_gc_alloc_region.release();
4319   // If we have an old GC alloc region to release, we'll save it in
4320   // _retained_old_gc_alloc_region. If we don't
4321   // _retained_old_gc_alloc_region will become NULL. This is what we
4322   // want either way so no reason to check explicitly for either
4323   // condition.
4324   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4325 
4326   if (ResizePLAB) {
4327     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4328     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4329   }
4330 }
4331 
4332 void G1CollectedHeap::abandon_gc_alloc_regions() {
4333   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4334   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4335   _retained_old_gc_alloc_region = NULL;
4336 }
4337 
4338 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4339   _drain_in_progress = false;
4340   set_evac_failure_closure(cl);
4341   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4342 }
4343 
4344 void G1CollectedHeap::finalize_for_evac_failure() {
4345   assert(_evac_failure_scan_stack != NULL &&
4346          _evac_failure_scan_stack->length() == 0,
4347          "Postcondition");
4348   assert(!_drain_in_progress, "Postcondition");
4349   delete _evac_failure_scan_stack;
4350   _evac_failure_scan_stack = NULL;
4351 }
4352 
4353 void G1CollectedHeap::remove_self_forwarding_pointers() {
4354   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4355 
4356   double remove_self_forwards_start = os::elapsedTime();
4357 
4358   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4359 
4360   if (G1CollectedHeap::use_parallel_gc_threads()) {
4361     set_par_threads();
4362     workers()->run_task(&rsfp_task);
4363     set_par_threads(0);
4364   } else {
4365     rsfp_task.work(0);
4366   }
4367 
4368   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4369 
4370   // Reset the claim values in the regions in the collection set.
4371   reset_cset_heap_region_claim_values();
4372 
4373   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4374 
4375   // Now restore saved marks, if any.
4376   assert(_objs_with_preserved_marks.size() ==
4377             _preserved_marks_of_objs.size(), "Both or none.");
4378   while (!_objs_with_preserved_marks.is_empty()) {
4379     oop obj = _objs_with_preserved_marks.pop();
4380     markOop m = _preserved_marks_of_objs.pop();
4381     obj->set_mark(m);
4382   }
4383   _objs_with_preserved_marks.clear(true);
4384   _preserved_marks_of_objs.clear(true);
4385 
4386   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4387 }
4388 
4389 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4390   _evac_failure_scan_stack->push(obj);
4391 }
4392 
4393 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4394   assert(_evac_failure_scan_stack != NULL, "precondition");
4395 
4396   while (_evac_failure_scan_stack->length() > 0) {
4397      oop obj = _evac_failure_scan_stack->pop();
4398      _evac_failure_closure->set_region(heap_region_containing(obj));
4399      obj->oop_iterate_backwards(_evac_failure_closure);
4400   }
4401 }
4402 
4403 oop
4404 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4405                                                oop old) {
4406   assert(obj_in_cs(old),
4407          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4408                  (HeapWord*) old));
4409   markOop m = old->mark();
4410   oop forward_ptr = old->forward_to_atomic(old);
4411   if (forward_ptr == NULL) {
4412     // Forward-to-self succeeded.
4413     assert(_par_scan_state != NULL, "par scan state");
4414     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4415     uint queue_num = _par_scan_state->queue_num();
4416 
4417     _evacuation_failed = true;
4418     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4419     if (_evac_failure_closure != cl) {
4420       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4421       assert(!_drain_in_progress,
4422              "Should only be true while someone holds the lock.");
4423       // Set the global evac-failure closure to the current thread's.
4424       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4425       set_evac_failure_closure(cl);
4426       // Now do the common part.
4427       handle_evacuation_failure_common(old, m);
4428       // Reset to NULL.
4429       set_evac_failure_closure(NULL);
4430     } else {
4431       // The lock is already held, and this is recursive.
4432       assert(_drain_in_progress, "This should only be the recursive case.");
4433       handle_evacuation_failure_common(old, m);
4434     }
4435     return old;
4436   } else {
4437     // Forward-to-self failed. Either someone else managed to allocate
4438     // space for this object (old != forward_ptr) or they beat us in
4439     // self-forwarding it (old == forward_ptr).
4440     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4441            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4442                    "should not be in the CSet",
4443                    (HeapWord*) old, (HeapWord*) forward_ptr));
4444     return forward_ptr;
4445   }
4446 }
4447 
4448 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4449   preserve_mark_if_necessary(old, m);
4450 
4451   HeapRegion* r = heap_region_containing(old);
4452   if (!r->evacuation_failed()) {
4453     r->set_evacuation_failed(true);
4454     _hr_printer.evac_failure(r);
4455   }
4456 
4457   push_on_evac_failure_scan_stack(old);
4458 
4459   if (!_drain_in_progress) {
4460     // prevent recursion in copy_to_survivor_space()
4461     _drain_in_progress = true;
4462     drain_evac_failure_scan_stack();
4463     _drain_in_progress = false;
4464   }
4465 }
4466 
4467 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4468   assert(evacuation_failed(), "Oversaving!");
4469   // We want to call the "for_promotion_failure" version only in the
4470   // case of a promotion failure.
4471   if (m->must_be_preserved_for_promotion_failure(obj)) {
4472     _objs_with_preserved_marks.push(obj);
4473     _preserved_marks_of_objs.push(m);
4474   }
4475 }
4476 
4477 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4478                                                   size_t word_size) {
4479   if (purpose == GCAllocForSurvived) {
4480     HeapWord* result = survivor_attempt_allocation(word_size);
4481     if (result != NULL) {
4482       return result;
4483     } else {
4484       // Let's try to allocate in the old gen in case we can fit the
4485       // object there.
4486       return old_attempt_allocation(word_size);
4487     }
4488   } else {
4489     assert(purpose ==  GCAllocForTenured, "sanity");
4490     HeapWord* result = old_attempt_allocation(word_size);
4491     if (result != NULL) {
4492       return result;
4493     } else {
4494       // Let's try to allocate in the survivors in case we can fit the
4495       // object there.
4496       return survivor_attempt_allocation(word_size);
4497     }
4498   }
4499 
4500   ShouldNotReachHere();
4501   // Trying to keep some compilers happy.
4502   return NULL;
4503 }
4504 
4505 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4506   ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4507 
4508 void G1ParCopyHelper::mark_object(oop obj) {
4509   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4510 
4511   // We know that the object is not moving so it's safe to read its size.
4512   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4513 }
4514 
4515 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4516   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4517   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4518   assert(from_obj != to_obj, "should not be self-forwarded");
4519 
4520   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4521   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4522 
4523   // The object might be in the process of being copied by another
4524   // worker so we cannot trust that its to-space image is
4525   // well-formed. So we have to read its size from its from-space
4526   // image which we know should not be changing.
4527   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4528 }
4529 
4530 template <class T>
4531 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4532   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4533     _scanned_klass->record_modified_oops();
4534   }
4535 }
4536 
4537 template <G1Barrier barrier, G1Mark do_mark_object>
4538 template <class T>
4539 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4540   T heap_oop = oopDesc::load_heap_oop(p);
4541 
4542   if (oopDesc::is_null(heap_oop)) {
4543     return;
4544   }
4545 
4546   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4547 
4548   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4549 
4550   G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4551 
4552   if (state == G1CollectedHeap::InCSet) {
4553     oop forwardee;
4554     if (obj->is_forwarded()) {
4555       forwardee = obj->forwardee();
4556     } else {
4557       forwardee = _par_scan_state->copy_to_survivor_space(obj);
4558     }
4559     assert(forwardee != NULL, "forwardee should not be NULL");
4560     oopDesc::encode_store_heap_oop(p, forwardee);
4561     if (do_mark_object != G1MarkNone && forwardee != obj) {
4562       // If the object is self-forwarded we don't need to explicitly
4563       // mark it, the evacuation failure protocol will do so.
4564       mark_forwarded_object(obj, forwardee);
4565     }
4566 
4567     if (barrier == G1BarrierKlass) {
4568       do_klass_barrier(p, forwardee);
4569     }
4570   } else {
4571     if (state == G1CollectedHeap::IsHumongous) {
4572       _g1->set_humongous_is_live(obj);
4573     }
4574     // The object is not in collection set. If we're a root scanning
4575     // closure during an initial mark pause then attempt to mark the object.
4576     if (do_mark_object == G1MarkFromRoot) {
4577       mark_object(obj);
4578     }
4579   }
4580 
4581   if (barrier == G1BarrierEvac) {
4582     _par_scan_state->update_rs(_from, p, _worker_id);
4583   }
4584 }
4585 
4586 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4587 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4588 
4589 class G1ParEvacuateFollowersClosure : public VoidClosure {
4590 protected:
4591   G1CollectedHeap*              _g1h;
4592   G1ParScanThreadState*         _par_scan_state;
4593   RefToScanQueueSet*            _queues;
4594   ParallelTaskTerminator*       _terminator;
4595 
4596   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4597   RefToScanQueueSet*      queues()         { return _queues; }
4598   ParallelTaskTerminator* terminator()     { return _terminator; }
4599 
4600 public:
4601   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4602                                 G1ParScanThreadState* par_scan_state,
4603                                 RefToScanQueueSet* queues,
4604                                 ParallelTaskTerminator* terminator)
4605     : _g1h(g1h), _par_scan_state(par_scan_state),
4606       _queues(queues), _terminator(terminator) {}
4607 
4608   void do_void();
4609 
4610 private:
4611   inline bool offer_termination();
4612 };
4613 
4614 bool G1ParEvacuateFollowersClosure::offer_termination() {
4615   G1ParScanThreadState* const pss = par_scan_state();
4616   pss->start_term_time();
4617   const bool res = terminator()->offer_termination();
4618   pss->end_term_time();
4619   return res;
4620 }
4621 
4622 void G1ParEvacuateFollowersClosure::do_void() {
4623   G1ParScanThreadState* const pss = par_scan_state();
4624   pss->trim_queue();
4625   do {
4626     pss->steal_and_trim_queue(queues());
4627   } while (!offer_termination());
4628 }
4629 
4630 class G1KlassScanClosure : public KlassClosure {
4631  G1ParCopyHelper* _closure;
4632  bool             _process_only_dirty;
4633  int              _count;
4634  public:
4635   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4636       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4637   void do_klass(Klass* klass) {
4638     // If the klass has not been dirtied we know that there's
4639     // no references into  the young gen and we can skip it.
4640    if (!_process_only_dirty || klass->has_modified_oops()) {
4641       // Clean the klass since we're going to scavenge all the metadata.
4642       klass->clear_modified_oops();
4643 
4644       // Tell the closure that this klass is the Klass to scavenge
4645       // and is the one to dirty if oops are left pointing into the young gen.
4646       _closure->set_scanned_klass(klass);
4647 
4648       klass->oops_do(_closure);
4649 
4650       _closure->set_scanned_klass(NULL);
4651     }
4652     _count++;
4653   }
4654 };
4655 
4656 class G1ParTask : public AbstractGangTask {
4657 protected:
4658   G1CollectedHeap*       _g1h;
4659   RefToScanQueueSet      *_queues;
4660   ParallelTaskTerminator _terminator;
4661   uint _n_workers;
4662 
4663   Mutex _stats_lock;
4664   Mutex* stats_lock() { return &_stats_lock; }
4665 
4666 public:
4667   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4668     : AbstractGangTask("G1 collection"),
4669       _g1h(g1h),
4670       _queues(task_queues),
4671       _terminator(0, _queues),
4672       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4673   {}
4674 
4675   RefToScanQueueSet* queues() { return _queues; }
4676 
4677   RefToScanQueue *work_queue(int i) {
4678     return queues()->queue(i);
4679   }
4680 
4681   ParallelTaskTerminator* terminator() { return &_terminator; }
4682 
4683   virtual void set_for_termination(int active_workers) {
4684     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4685     // in the young space (_par_seq_tasks) in the G1 heap
4686     // for SequentialSubTasksDone.
4687     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4688     // both of which need setting by set_n_termination().
4689     _g1h->SharedHeap::set_n_termination(active_workers);
4690     _g1h->set_n_termination(active_workers);
4691     terminator()->reset_for_reuse(active_workers);
4692     _n_workers = active_workers;
4693   }
4694 
4695   // Helps out with CLD processing.
4696   //
4697   // During InitialMark we need to:
4698   // 1) Scavenge all CLDs for the young GC.
4699   // 2) Mark all objects directly reachable from strong CLDs.
4700   template <G1Mark do_mark_object>
4701   class G1CLDClosure : public CLDClosure {
4702     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4703     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4704     G1KlassScanClosure                                _klass_in_cld_closure;
4705     bool                                              _claim;
4706 
4707    public:
4708     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4709                  bool only_young, bool claim)
4710         : _oop_closure(oop_closure),
4711           _oop_in_klass_closure(oop_closure->g1(),
4712                                 oop_closure->pss(),
4713                                 oop_closure->rp()),
4714           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4715           _claim(claim) {
4716 
4717     }
4718 
4719     void do_cld(ClassLoaderData* cld) {
4720       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4721     }
4722   };
4723 
4724   class G1CodeBlobClosure: public CodeBlobClosure {
4725     OopClosure* _f;
4726 
4727    public:
4728     G1CodeBlobClosure(OopClosure* f) : _f(f) {}
4729     void do_code_blob(CodeBlob* blob) {
4730       nmethod* that = blob->as_nmethod_or_null();
4731       if (that != NULL) {
4732         if (!that->test_set_oops_do_mark()) {
4733           that->oops_do(_f);
4734           that->fix_oop_relocations();
4735         }
4736       }
4737     }
4738   };
4739 
4740   void work(uint worker_id) {
4741     if (worker_id >= _n_workers) return;  // no work needed this round
4742 
4743     double start_time_ms = os::elapsedTime() * 1000.0;
4744     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4745 
4746     {
4747       ResourceMark rm;
4748       HandleMark   hm;
4749 
4750       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4751 
4752       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4753       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4754 
4755       pss.set_evac_failure_closure(&evac_failure_cl);
4756 
4757       bool only_young = _g1h->g1_policy()->gcs_are_young();
4758 
4759       // Non-IM young GC.
4760       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4761       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4762                                                                                only_young, // Only process dirty klasses.
4763                                                                                false);     // No need to claim CLDs.
4764       // IM young GC.
4765       //    Strong roots closures.
4766       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4767       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4768                                                                                false, // Process all klasses.
4769                                                                                true); // Need to claim CLDs.
4770       //    Weak roots closures.
4771       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4772       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4773                                                                                     false, // Process all klasses.
4774                                                                                     true); // Need to claim CLDs.
4775 
4776       G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4777       G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4778       // IM Weak code roots are handled later.
4779 
4780       OopClosure* strong_root_cl;
4781       OopClosure* weak_root_cl;
4782       CLDClosure* strong_cld_cl;
4783       CLDClosure* weak_cld_cl;
4784       CodeBlobClosure* strong_code_cl;
4785 
4786       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4787         // We also need to mark copied objects.
4788         strong_root_cl = &scan_mark_root_cl;
4789         strong_cld_cl  = &scan_mark_cld_cl;
4790         strong_code_cl = &scan_mark_code_cl;
4791         if (ClassUnloadingWithConcurrentMark) {
4792           weak_root_cl = &scan_mark_weak_root_cl;
4793           weak_cld_cl  = &scan_mark_weak_cld_cl;
4794         } else {
4795           weak_root_cl = &scan_mark_root_cl;
4796           weak_cld_cl  = &scan_mark_cld_cl;
4797         }
4798       } else {
4799         strong_root_cl = &scan_only_root_cl;
4800         weak_root_cl   = &scan_only_root_cl;
4801         strong_cld_cl  = &scan_only_cld_cl;
4802         weak_cld_cl    = &scan_only_cld_cl;
4803         strong_code_cl = &scan_only_code_cl;
4804       }
4805 
4806 
4807       G1ParPushHeapRSClosure  push_heap_rs_cl(_g1h, &pss);
4808 
4809       pss.start_strong_roots();
4810       _g1h->g1_process_roots(strong_root_cl,
4811                              weak_root_cl,
4812                              &push_heap_rs_cl,
4813                              strong_cld_cl,
4814                              weak_cld_cl,
4815                              strong_code_cl,
4816                              worker_id);
4817 
4818       pss.end_strong_roots();
4819 
4820       {
4821         double start = os::elapsedTime();
4822         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4823         evac.do_void();
4824         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4825         double term_ms = pss.term_time()*1000.0;
4826         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4827         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4828       }
4829       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4830       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4831 
4832       if (ParallelGCVerbose) {
4833         MutexLocker x(stats_lock());
4834         pss.print_termination_stats(worker_id);
4835       }
4836 
4837       assert(pss.queue_is_empty(), "should be empty");
4838 
4839       // Close the inner scope so that the ResourceMark and HandleMark
4840       // destructors are executed here and are included as part of the
4841       // "GC Worker Time".
4842     }
4843 
4844     double end_time_ms = os::elapsedTime() * 1000.0;
4845     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4846   }
4847 };
4848 
4849 // *** Common G1 Evacuation Stuff
4850 
4851 // This method is run in a GC worker.
4852 
4853 void
4854 G1CollectedHeap::
4855 g1_process_roots(OopClosure* scan_non_heap_roots,
4856                  OopClosure* scan_non_heap_weak_roots,
4857                  OopsInHeapRegionClosure* scan_rs,
4858                  CLDClosure* scan_strong_clds,
4859                  CLDClosure* scan_weak_clds,
4860                  CodeBlobClosure* scan_strong_code,
4861                  uint worker_i) {
4862 
4863   // First scan the shared roots.
4864   double ext_roots_start = os::elapsedTime();
4865   double closure_app_time_sec = 0.0;
4866 
4867   bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4868   bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4869 
4870   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4871   BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4872 
4873   process_roots(false, // no scoping; this is parallel code
4874                 SharedHeap::SO_None,
4875                 &buf_scan_non_heap_roots,
4876                 &buf_scan_non_heap_weak_roots,
4877                 scan_strong_clds,
4878                 // Unloading Initial Marks handle the weak CLDs separately.
4879                 (trace_metadata ? NULL : scan_weak_clds),
4880                 scan_strong_code);
4881 
4882   // Now the CM ref_processor roots.
4883   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4884     // We need to treat the discovered reference lists of the
4885     // concurrent mark ref processor as roots and keep entries
4886     // (which are added by the marking threads) on them live
4887     // until they can be processed at the end of marking.
4888     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4889   }
4890 
4891   if (trace_metadata) {
4892     // Barrier to make sure all workers passed
4893     // the strong CLD and strong nmethods phases.
4894     active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4895 
4896     // Now take the complement of the strong CLDs.
4897     ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4898   }
4899 
4900   // Finish up any enqueued closure apps (attributed as object copy time).
4901   buf_scan_non_heap_roots.done();
4902   buf_scan_non_heap_weak_roots.done();
4903 
4904   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4905       + buf_scan_non_heap_weak_roots.closure_app_seconds();
4906 
4907   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4908 
4909   double ext_root_time_ms =
4910     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4911 
4912   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4913 
4914   // During conc marking we have to filter the per-thread SATB buffers
4915   // to make sure we remove any oops into the CSet (which will show up
4916   // as implicitly live).
4917   double satb_filtering_ms = 0.0;
4918   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4919     if (mark_in_progress()) {
4920       double satb_filter_start = os::elapsedTime();
4921 
4922       JavaThread::satb_mark_queue_set().filter_thread_buffers();
4923 
4924       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4925     }
4926   }
4927   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4928 
4929   // Now scan the complement of the collection set.
4930   MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations);
4931 
4932   g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4933 
4934   _process_strong_tasks->all_tasks_completed();
4935 }
4936 
4937 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4938 private:
4939   BoolObjectClosure* _is_alive;
4940   int _initial_string_table_size;
4941   int _initial_symbol_table_size;
4942 
4943   bool  _process_strings;
4944   int _strings_processed;
4945   int _strings_removed;
4946 
4947   bool  _process_symbols;
4948   int _symbols_processed;
4949   int _symbols_removed;
4950 
4951   bool _do_in_parallel;
4952 public:
4953   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4954     AbstractGangTask("String/Symbol Unlinking"),
4955     _is_alive(is_alive),
4956     _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4957     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4958     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4959 
4960     _initial_string_table_size = StringTable::the_table()->table_size();
4961     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4962     if (process_strings) {
4963       StringTable::clear_parallel_claimed_index();
4964     }
4965     if (process_symbols) {
4966       SymbolTable::clear_parallel_claimed_index();
4967     }
4968   }
4969 
4970   ~G1StringSymbolTableUnlinkTask() {
4971     guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4972               err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4973                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4974     guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4975               err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4976                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4977 
4978     if (G1TraceStringSymbolTableScrubbing) {
4979       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4980                              "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4981                              "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4982                              strings_processed(), strings_removed(),
4983                              symbols_processed(), symbols_removed());
4984     }
4985   }
4986 
4987   void work(uint worker_id) {
4988     if (_do_in_parallel) {
4989       int strings_processed = 0;
4990       int strings_removed = 0;
4991       int symbols_processed = 0;
4992       int symbols_removed = 0;
4993       if (_process_strings) {
4994         StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4995         Atomic::add(strings_processed, &_strings_processed);
4996         Atomic::add(strings_removed, &_strings_removed);
4997       }
4998       if (_process_symbols) {
4999         SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5000         Atomic::add(symbols_processed, &_symbols_processed);
5001         Atomic::add(symbols_removed, &_symbols_removed);
5002       }
5003     } else {
5004       if (_process_strings) {
5005         StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5006       }
5007       if (_process_symbols) {
5008         SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5009       }
5010     }
5011   }
5012 
5013   size_t strings_processed() const { return (size_t)_strings_processed; }
5014   size_t strings_removed()   const { return (size_t)_strings_removed; }
5015 
5016   size_t symbols_processed() const { return (size_t)_symbols_processed; }
5017   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
5018 };
5019 
5020 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
5021 private:
5022   static Monitor* _lock;
5023 
5024   BoolObjectClosure* const _is_alive;
5025   const bool               _unloading_occurred;
5026   const uint               _num_workers;
5027 
5028   // Variables used to claim nmethods.
5029   nmethod* _first_nmethod;
5030   volatile nmethod* _claimed_nmethod;
5031 
5032   // The list of nmethods that need to be processed by the second pass.
5033   volatile nmethod* _postponed_list;
5034   volatile uint     _num_entered_barrier;
5035 
5036  public:
5037   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
5038       _is_alive(is_alive),
5039       _unloading_occurred(unloading_occurred),
5040       _num_workers(num_workers),
5041       _first_nmethod(NULL),
5042       _claimed_nmethod(NULL),
5043       _postponed_list(NULL),
5044       _num_entered_barrier(0)
5045   {
5046     nmethod::increase_unloading_clock();
5047     _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
5048     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
5049   }
5050 
5051   ~G1CodeCacheUnloadingTask() {
5052     CodeCache::verify_clean_inline_caches();
5053 
5054     CodeCache::set_needs_cache_clean(false);
5055     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
5056 
5057     CodeCache::verify_icholder_relocations();
5058   }
5059 
5060  private:
5061   void add_to_postponed_list(nmethod* nm) {
5062       nmethod* old;
5063       do {
5064         old = (nmethod*)_postponed_list;
5065         nm->set_unloading_next(old);
5066       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
5067   }
5068 
5069   void clean_nmethod(nmethod* nm) {
5070     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
5071 
5072     if (postponed) {
5073       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
5074       add_to_postponed_list(nm);
5075     }
5076 
5077     // Mark that this thread has been cleaned/unloaded.
5078     // After this call, it will be safe to ask if this nmethod was unloaded or not.
5079     nm->set_unloading_clock(nmethod::global_unloading_clock());
5080   }
5081 
5082   void clean_nmethod_postponed(nmethod* nm) {
5083     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
5084   }
5085 
5086   static const int MaxClaimNmethods = 16;
5087 
5088   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
5089     nmethod* first;
5090     nmethod* last;
5091 
5092     do {
5093       *num_claimed_nmethods = 0;
5094 
5095       first = last = (nmethod*)_claimed_nmethod;
5096 
5097       if (first != NULL) {
5098         for (int i = 0; i < MaxClaimNmethods; i++) {
5099           last = CodeCache::alive_nmethod(CodeCache::next(last));
5100 
5101           if (last == NULL) {
5102             break;
5103           }
5104 
5105           claimed_nmethods[i] = last;
5106           (*num_claimed_nmethods)++;
5107         }
5108       }
5109 
5110     } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
5111   }
5112 
5113   nmethod* claim_postponed_nmethod() {
5114     nmethod* claim;
5115     nmethod* next;
5116 
5117     do {
5118       claim = (nmethod*)_postponed_list;
5119       if (claim == NULL) {
5120         return NULL;
5121       }
5122 
5123       next = claim->unloading_next();
5124 
5125     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
5126 
5127     return claim;
5128   }
5129 
5130  public:
5131   // Mark that we're done with the first pass of nmethod cleaning.
5132   void barrier_mark(uint worker_id) {
5133     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5134     _num_entered_barrier++;
5135     if (_num_entered_barrier == _num_workers) {
5136       ml.notify_all();
5137     }
5138   }
5139 
5140   // See if we have to wait for the other workers to
5141   // finish their first-pass nmethod cleaning work.
5142   void barrier_wait(uint worker_id) {
5143     if (_num_entered_barrier < _num_workers) {
5144       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5145       while (_num_entered_barrier < _num_workers) {
5146           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5147       }
5148     }
5149   }
5150 
5151   // Cleaning and unloading of nmethods. Some work has to be postponed
5152   // to the second pass, when we know which nmethods survive.
5153   void work_first_pass(uint worker_id) {
5154     // The first nmethods is claimed by the first worker.
5155     if (worker_id == 0 && _first_nmethod != NULL) {
5156       clean_nmethod(_first_nmethod);
5157       _first_nmethod = NULL;
5158     }
5159 
5160     int num_claimed_nmethods;
5161     nmethod* claimed_nmethods[MaxClaimNmethods];
5162 
5163     while (true) {
5164       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5165 
5166       if (num_claimed_nmethods == 0) {
5167         break;
5168       }
5169 
5170       for (int i = 0; i < num_claimed_nmethods; i++) {
5171         clean_nmethod(claimed_nmethods[i]);
5172       }
5173     }
5174   }
5175 
5176   void work_second_pass(uint worker_id) {
5177     nmethod* nm;
5178     // Take care of postponed nmethods.
5179     while ((nm = claim_postponed_nmethod()) != NULL) {
5180       clean_nmethod_postponed(nm);
5181     }
5182   }
5183 };
5184 
5185 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5186 
5187 class G1KlassCleaningTask : public StackObj {
5188   BoolObjectClosure*                      _is_alive;
5189   volatile jint                           _clean_klass_tree_claimed;
5190   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5191 
5192  public:
5193   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5194       _is_alive(is_alive),
5195       _clean_klass_tree_claimed(0),
5196       _klass_iterator() {
5197   }
5198 
5199  private:
5200   bool claim_clean_klass_tree_task() {
5201     if (_clean_klass_tree_claimed) {
5202       return false;
5203     }
5204 
5205     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5206   }
5207 
5208   InstanceKlass* claim_next_klass() {
5209     Klass* klass;
5210     do {
5211       klass =_klass_iterator.next_klass();
5212     } while (klass != NULL && !klass->oop_is_instance());
5213 
5214     return (InstanceKlass*)klass;
5215   }
5216 
5217 public:
5218 
5219   void clean_klass(InstanceKlass* ik) {
5220     ik->clean_implementors_list(_is_alive);
5221     ik->clean_method_data(_is_alive);
5222 
5223     // G1 specific cleanup work that has
5224     // been moved here to be done in parallel.
5225     ik->clean_dependent_nmethods();
5226   }
5227 
5228   void work() {
5229     ResourceMark rm;
5230 
5231     // One worker will clean the subklass/sibling klass tree.
5232     if (claim_clean_klass_tree_task()) {
5233       Klass::clean_subklass_tree(_is_alive);
5234     }
5235 
5236     // All workers will help cleaning the classes,
5237     InstanceKlass* klass;
5238     while ((klass = claim_next_klass()) != NULL) {
5239       clean_klass(klass);
5240     }
5241   }
5242 };
5243 
5244 // To minimize the remark pause times, the tasks below are done in parallel.
5245 class G1ParallelCleaningTask : public AbstractGangTask {
5246 private:
5247   G1StringSymbolTableUnlinkTask _string_symbol_task;
5248   G1CodeCacheUnloadingTask      _code_cache_task;
5249   G1KlassCleaningTask           _klass_cleaning_task;
5250 
5251 public:
5252   // The constructor is run in the VMThread.
5253   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5254       AbstractGangTask("Parallel Cleaning"),
5255       _string_symbol_task(is_alive, process_strings, process_symbols),
5256       _code_cache_task(num_workers, is_alive, unloading_occurred),
5257       _klass_cleaning_task(is_alive) {
5258   }
5259 
5260   // The parallel work done by all worker threads.
5261   void work(uint worker_id) {
5262     // Do first pass of code cache cleaning.
5263     _code_cache_task.work_first_pass(worker_id);
5264 
5265     // Let the threads mark that the first pass is done.
5266     _code_cache_task.barrier_mark(worker_id);
5267 
5268     // Clean the Strings and Symbols.
5269     _string_symbol_task.work(worker_id);
5270 
5271     // Wait for all workers to finish the first code cache cleaning pass.
5272     _code_cache_task.barrier_wait(worker_id);
5273 
5274     // Do the second code cache cleaning work, which realize on
5275     // the liveness information gathered during the first pass.
5276     _code_cache_task.work_second_pass(worker_id);
5277 
5278     // Clean all klasses that were not unloaded.
5279     _klass_cleaning_task.work();
5280   }
5281 };
5282 
5283 
5284 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5285                                         bool process_strings,
5286                                         bool process_symbols,
5287                                         bool class_unloading_occurred) {
5288   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5289                     workers()->active_workers() : 1);
5290 
5291   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5292                                         n_workers, class_unloading_occurred);
5293   if (G1CollectedHeap::use_parallel_gc_threads()) {
5294     set_par_threads(n_workers);
5295     workers()->run_task(&g1_unlink_task);
5296     set_par_threads(0);
5297   } else {
5298     g1_unlink_task.work(0);
5299   }
5300 }
5301 
5302 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5303                                                      bool process_strings, bool process_symbols) {
5304   {
5305     uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5306                      _g1h->workers()->active_workers() : 1);
5307     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5308     if (G1CollectedHeap::use_parallel_gc_threads()) {
5309       set_par_threads(n_workers);
5310       workers()->run_task(&g1_unlink_task);
5311       set_par_threads(0);
5312     } else {
5313       g1_unlink_task.work(0);
5314     }
5315   }
5316 
5317   if (G1StringDedup::is_enabled()) {
5318     G1StringDedup::unlink(is_alive);
5319   }
5320 }
5321 
5322 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5323  private:
5324   DirtyCardQueueSet* _queue;
5325  public:
5326   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5327 
5328   virtual void work(uint worker_id) {
5329     double start_time = os::elapsedTime();
5330 
5331     RedirtyLoggedCardTableEntryClosure cl;
5332     if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5333       _queue->par_apply_closure_to_all_completed_buffers(&cl);
5334     } else {
5335       _queue->apply_closure_to_all_completed_buffers(&cl);
5336     }
5337 
5338     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5339     timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5340     timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5341   }
5342 };
5343 
5344 void G1CollectedHeap::redirty_logged_cards() {
5345   guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5346   double redirty_logged_cards_start = os::elapsedTime();
5347 
5348   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5349                    _g1h->workers()->active_workers() : 1);
5350 
5351   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5352   dirty_card_queue_set().reset_for_par_iteration();
5353   if (use_parallel_gc_threads()) {
5354     set_par_threads(n_workers);
5355     workers()->run_task(&redirty_task);
5356     set_par_threads(0);
5357   } else {
5358     redirty_task.work(0);
5359   }
5360 
5361   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5362   dcq.merge_bufferlists(&dirty_card_queue_set());
5363   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5364 
5365   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5366 }
5367 
5368 // Weak Reference Processing support
5369 
5370 // An always "is_alive" closure that is used to preserve referents.
5371 // If the object is non-null then it's alive.  Used in the preservation
5372 // of referent objects that are pointed to by reference objects
5373 // discovered by the CM ref processor.
5374 class G1AlwaysAliveClosure: public BoolObjectClosure {
5375   G1CollectedHeap* _g1;
5376 public:
5377   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5378   bool do_object_b(oop p) {
5379     if (p != NULL) {
5380       return true;
5381     }
5382     return false;
5383   }
5384 };
5385 
5386 bool G1STWIsAliveClosure::do_object_b(oop p) {
5387   // An object is reachable if it is outside the collection set,
5388   // or is inside and copied.
5389   return !_g1->obj_in_cs(p) || p->is_forwarded();
5390 }
5391 
5392 // Non Copying Keep Alive closure
5393 class G1KeepAliveClosure: public OopClosure {
5394   G1CollectedHeap* _g1;
5395 public:
5396   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5397   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5398   void do_oop(oop* p) {
5399     oop obj = *p;
5400 
5401     G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5402     if (obj == NULL || cset_state == G1CollectedHeap::InNeither) {
5403       return;
5404     }
5405     if (cset_state == G1CollectedHeap::InCSet) {
5406       assert( obj->is_forwarded(), "invariant" );
5407       *p = obj->forwardee();
5408     } else {
5409       assert(!obj->is_forwarded(), "invariant" );
5410       assert(cset_state == G1CollectedHeap::IsHumongous,
5411              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5412       _g1->set_humongous_is_live(obj);
5413     }
5414   }
5415 };
5416 
5417 // Copying Keep Alive closure - can be called from both
5418 // serial and parallel code as long as different worker
5419 // threads utilize different G1ParScanThreadState instances
5420 // and different queues.
5421 
5422 class G1CopyingKeepAliveClosure: public OopClosure {
5423   G1CollectedHeap*         _g1h;
5424   OopClosure*              _copy_non_heap_obj_cl;
5425   G1ParScanThreadState*    _par_scan_state;
5426 
5427 public:
5428   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5429                             OopClosure* non_heap_obj_cl,
5430                             G1ParScanThreadState* pss):
5431     _g1h(g1h),
5432     _copy_non_heap_obj_cl(non_heap_obj_cl),
5433     _par_scan_state(pss)
5434   {}
5435 
5436   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5437   virtual void do_oop(      oop* p) { do_oop_work(p); }
5438 
5439   template <class T> void do_oop_work(T* p) {
5440     oop obj = oopDesc::load_decode_heap_oop(p);
5441 
5442     if (_g1h->is_in_cset_or_humongous(obj)) {
5443       // If the referent object has been forwarded (either copied
5444       // to a new location or to itself in the event of an
5445       // evacuation failure) then we need to update the reference
5446       // field and, if both reference and referent are in the G1
5447       // heap, update the RSet for the referent.
5448       //
5449       // If the referent has not been forwarded then we have to keep
5450       // it alive by policy. Therefore we have copy the referent.
5451       //
5452       // If the reference field is in the G1 heap then we can push
5453       // on the PSS queue. When the queue is drained (after each
5454       // phase of reference processing) the object and it's followers
5455       // will be copied, the reference field set to point to the
5456       // new location, and the RSet updated. Otherwise we need to
5457       // use the the non-heap or metadata closures directly to copy
5458       // the referent object and update the pointer, while avoiding
5459       // updating the RSet.
5460 
5461       if (_g1h->is_in_g1_reserved(p)) {
5462         _par_scan_state->push_on_queue(p);
5463       } else {
5464         assert(!Metaspace::contains((const void*)p),
5465                err_msg("Unexpectedly found a pointer from metadata: "
5466                               PTR_FORMAT, p));
5467         _copy_non_heap_obj_cl->do_oop(p);
5468       }
5469     }
5470   }
5471 };
5472 
5473 // Serial drain queue closure. Called as the 'complete_gc'
5474 // closure for each discovered list in some of the
5475 // reference processing phases.
5476 
5477 class G1STWDrainQueueClosure: public VoidClosure {
5478 protected:
5479   G1CollectedHeap* _g1h;
5480   G1ParScanThreadState* _par_scan_state;
5481 
5482   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5483 
5484 public:
5485   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5486     _g1h(g1h),
5487     _par_scan_state(pss)
5488   { }
5489 
5490   void do_void() {
5491     G1ParScanThreadState* const pss = par_scan_state();
5492     pss->trim_queue();
5493   }
5494 };
5495 
5496 // Parallel Reference Processing closures
5497 
5498 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5499 // processing during G1 evacuation pauses.
5500 
5501 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5502 private:
5503   G1CollectedHeap*   _g1h;
5504   RefToScanQueueSet* _queues;
5505   FlexibleWorkGang*  _workers;
5506   int                _active_workers;
5507 
5508 public:
5509   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5510                         FlexibleWorkGang* workers,
5511                         RefToScanQueueSet *task_queues,
5512                         int n_workers) :
5513     _g1h(g1h),
5514     _queues(task_queues),
5515     _workers(workers),
5516     _active_workers(n_workers)
5517   {
5518     assert(n_workers > 0, "shouldn't call this otherwise");
5519   }
5520 
5521   // Executes the given task using concurrent marking worker threads.
5522   virtual void execute(ProcessTask& task);
5523   virtual void execute(EnqueueTask& task);
5524 };
5525 
5526 // Gang task for possibly parallel reference processing
5527 
5528 class G1STWRefProcTaskProxy: public AbstractGangTask {
5529   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5530   ProcessTask&     _proc_task;
5531   G1CollectedHeap* _g1h;
5532   RefToScanQueueSet *_task_queues;
5533   ParallelTaskTerminator* _terminator;
5534 
5535 public:
5536   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5537                      G1CollectedHeap* g1h,
5538                      RefToScanQueueSet *task_queues,
5539                      ParallelTaskTerminator* terminator) :
5540     AbstractGangTask("Process reference objects in parallel"),
5541     _proc_task(proc_task),
5542     _g1h(g1h),
5543     _task_queues(task_queues),
5544     _terminator(terminator)
5545   {}
5546 
5547   virtual void work(uint worker_id) {
5548     // The reference processing task executed by a single worker.
5549     ResourceMark rm;
5550     HandleMark   hm;
5551 
5552     G1STWIsAliveClosure is_alive(_g1h);
5553 
5554     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5555     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5556 
5557     pss.set_evac_failure_closure(&evac_failure_cl);
5558 
5559     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5560 
5561     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5562 
5563     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5564 
5565     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5566       // We also need to mark copied objects.
5567       copy_non_heap_cl = &copy_mark_non_heap_cl;
5568     }
5569 
5570     // Keep alive closure.
5571     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5572 
5573     // Complete GC closure
5574     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5575 
5576     // Call the reference processing task's work routine.
5577     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5578 
5579     // Note we cannot assert that the refs array is empty here as not all
5580     // of the processing tasks (specifically phase2 - pp2_work) execute
5581     // the complete_gc closure (which ordinarily would drain the queue) so
5582     // the queue may not be empty.
5583   }
5584 };
5585 
5586 // Driver routine for parallel reference processing.
5587 // Creates an instance of the ref processing gang
5588 // task and has the worker threads execute it.
5589 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5590   assert(_workers != NULL, "Need parallel worker threads.");
5591 
5592   ParallelTaskTerminator terminator(_active_workers, _queues);
5593   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5594 
5595   _g1h->set_par_threads(_active_workers);
5596   _workers->run_task(&proc_task_proxy);
5597   _g1h->set_par_threads(0);
5598 }
5599 
5600 // Gang task for parallel reference enqueueing.
5601 
5602 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5603   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5604   EnqueueTask& _enq_task;
5605 
5606 public:
5607   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5608     AbstractGangTask("Enqueue reference objects in parallel"),
5609     _enq_task(enq_task)
5610   { }
5611 
5612   virtual void work(uint worker_id) {
5613     _enq_task.work(worker_id);
5614   }
5615 };
5616 
5617 // Driver routine for parallel reference enqueueing.
5618 // Creates an instance of the ref enqueueing gang
5619 // task and has the worker threads execute it.
5620 
5621 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5622   assert(_workers != NULL, "Need parallel worker threads.");
5623 
5624   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5625 
5626   _g1h->set_par_threads(_active_workers);
5627   _workers->run_task(&enq_task_proxy);
5628   _g1h->set_par_threads(0);
5629 }
5630 
5631 // End of weak reference support closures
5632 
5633 // Abstract task used to preserve (i.e. copy) any referent objects
5634 // that are in the collection set and are pointed to by reference
5635 // objects discovered by the CM ref processor.
5636 
5637 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5638 protected:
5639   G1CollectedHeap* _g1h;
5640   RefToScanQueueSet      *_queues;
5641   ParallelTaskTerminator _terminator;
5642   uint _n_workers;
5643 
5644 public:
5645   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5646     AbstractGangTask("ParPreserveCMReferents"),
5647     _g1h(g1h),
5648     _queues(task_queues),
5649     _terminator(workers, _queues),
5650     _n_workers(workers)
5651   { }
5652 
5653   void work(uint worker_id) {
5654     ResourceMark rm;
5655     HandleMark   hm;
5656 
5657     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5658     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5659 
5660     pss.set_evac_failure_closure(&evac_failure_cl);
5661 
5662     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5663 
5664     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5665 
5666     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5667 
5668     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5669 
5670     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5671       // We also need to mark copied objects.
5672       copy_non_heap_cl = &copy_mark_non_heap_cl;
5673     }
5674 
5675     // Is alive closure
5676     G1AlwaysAliveClosure always_alive(_g1h);
5677 
5678     // Copying keep alive closure. Applied to referent objects that need
5679     // to be copied.
5680     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5681 
5682     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5683 
5684     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5685     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5686 
5687     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5688     // So this must be true - but assert just in case someone decides to
5689     // change the worker ids.
5690     assert(0 <= worker_id && worker_id < limit, "sanity");
5691     assert(!rp->discovery_is_atomic(), "check this code");
5692 
5693     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5694     for (uint idx = worker_id; idx < limit; idx += stride) {
5695       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5696 
5697       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5698       while (iter.has_next()) {
5699         // Since discovery is not atomic for the CM ref processor, we
5700         // can see some null referent objects.
5701         iter.load_ptrs(DEBUG_ONLY(true));
5702         oop ref = iter.obj();
5703 
5704         // This will filter nulls.
5705         if (iter.is_referent_alive()) {
5706           iter.make_referent_alive();
5707         }
5708         iter.move_to_next();
5709       }
5710     }
5711 
5712     // Drain the queue - which may cause stealing
5713     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5714     drain_queue.do_void();
5715     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5716     assert(pss.queue_is_empty(), "should be");
5717   }
5718 };
5719 
5720 // Weak Reference processing during an evacuation pause (part 1).
5721 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5722   double ref_proc_start = os::elapsedTime();
5723 
5724   ReferenceProcessor* rp = _ref_processor_stw;
5725   assert(rp->discovery_enabled(), "should have been enabled");
5726 
5727   // Any reference objects, in the collection set, that were 'discovered'
5728   // by the CM ref processor should have already been copied (either by
5729   // applying the external root copy closure to the discovered lists, or
5730   // by following an RSet entry).
5731   //
5732   // But some of the referents, that are in the collection set, that these
5733   // reference objects point to may not have been copied: the STW ref
5734   // processor would have seen that the reference object had already
5735   // been 'discovered' and would have skipped discovering the reference,
5736   // but would not have treated the reference object as a regular oop.
5737   // As a result the copy closure would not have been applied to the
5738   // referent object.
5739   //
5740   // We need to explicitly copy these referent objects - the references
5741   // will be processed at the end of remarking.
5742   //
5743   // We also need to do this copying before we process the reference
5744   // objects discovered by the STW ref processor in case one of these
5745   // referents points to another object which is also referenced by an
5746   // object discovered by the STW ref processor.
5747 
5748   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5749            no_of_gc_workers == workers()->active_workers(),
5750            "Need to reset active GC workers");
5751 
5752   set_par_threads(no_of_gc_workers);
5753   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5754                                                  no_of_gc_workers,
5755                                                  _task_queues);
5756 
5757   if (G1CollectedHeap::use_parallel_gc_threads()) {
5758     workers()->run_task(&keep_cm_referents);
5759   } else {
5760     keep_cm_referents.work(0);
5761   }
5762 
5763   set_par_threads(0);
5764 
5765   // Closure to test whether a referent is alive.
5766   G1STWIsAliveClosure is_alive(this);
5767 
5768   // Even when parallel reference processing is enabled, the processing
5769   // of JNI refs is serial and performed serially by the current thread
5770   // rather than by a worker. The following PSS will be used for processing
5771   // JNI refs.
5772 
5773   // Use only a single queue for this PSS.
5774   G1ParScanThreadState            pss(this, 0, NULL);
5775 
5776   // We do not embed a reference processor in the copying/scanning
5777   // closures while we're actually processing the discovered
5778   // reference objects.
5779   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5780 
5781   pss.set_evac_failure_closure(&evac_failure_cl);
5782 
5783   assert(pss.queue_is_empty(), "pre-condition");
5784 
5785   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5786 
5787   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5788 
5789   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5790 
5791   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5792     // We also need to mark copied objects.
5793     copy_non_heap_cl = &copy_mark_non_heap_cl;
5794   }
5795 
5796   // Keep alive closure.
5797   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5798 
5799   // Serial Complete GC closure
5800   G1STWDrainQueueClosure drain_queue(this, &pss);
5801 
5802   // Setup the soft refs policy...
5803   rp->setup_policy(false);
5804 
5805   ReferenceProcessorStats stats;
5806   if (!rp->processing_is_mt()) {
5807     // Serial reference processing...
5808     stats = rp->process_discovered_references(&is_alive,
5809                                               &keep_alive,
5810                                               &drain_queue,
5811                                               NULL,
5812                                               _gc_timer_stw,
5813                                               _gc_tracer_stw->gc_id());
5814   } else {
5815     // Parallel reference processing
5816     assert(rp->num_q() == no_of_gc_workers, "sanity");
5817     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5818 
5819     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5820     stats = rp->process_discovered_references(&is_alive,
5821                                               &keep_alive,
5822                                               &drain_queue,
5823                                               &par_task_executor,
5824                                               _gc_timer_stw,
5825                                               _gc_tracer_stw->gc_id());
5826   }
5827 
5828   _gc_tracer_stw->report_gc_reference_stats(stats);
5829 
5830   // We have completed copying any necessary live referent objects.
5831   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5832 
5833   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5834   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5835 }
5836 
5837 // Weak Reference processing during an evacuation pause (part 2).
5838 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5839   double ref_enq_start = os::elapsedTime();
5840 
5841   ReferenceProcessor* rp = _ref_processor_stw;
5842   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5843 
5844   // Now enqueue any remaining on the discovered lists on to
5845   // the pending list.
5846   if (!rp->processing_is_mt()) {
5847     // Serial reference processing...
5848     rp->enqueue_discovered_references();
5849   } else {
5850     // Parallel reference enqueueing
5851 
5852     assert(no_of_gc_workers == workers()->active_workers(),
5853            "Need to reset active workers");
5854     assert(rp->num_q() == no_of_gc_workers, "sanity");
5855     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5856 
5857     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5858     rp->enqueue_discovered_references(&par_task_executor);
5859   }
5860 
5861   rp->verify_no_references_recorded();
5862   assert(!rp->discovery_enabled(), "should have been disabled");
5863 
5864   // FIXME
5865   // CM's reference processing also cleans up the string and symbol tables.
5866   // Should we do that here also? We could, but it is a serial operation
5867   // and could significantly increase the pause time.
5868 
5869   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5870   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5871 }
5872 
5873 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5874   _expand_heap_after_alloc_failure = true;
5875   _evacuation_failed = false;
5876 
5877   // Should G1EvacuationFailureALot be in effect for this GC?
5878   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5879 
5880   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5881 
5882   // Disable the hot card cache.
5883   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5884   hot_card_cache->reset_hot_cache_claimed_index();
5885   hot_card_cache->set_use_cache(false);
5886 
5887   uint n_workers;
5888   if (G1CollectedHeap::use_parallel_gc_threads()) {
5889     n_workers =
5890       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5891                                      workers()->active_workers(),
5892                                      Threads::number_of_non_daemon_threads());
5893     assert(UseDynamicNumberOfGCThreads ||
5894            n_workers == workers()->total_workers(),
5895            "If not dynamic should be using all the  workers");
5896     workers()->set_active_workers(n_workers);
5897     set_par_threads(n_workers);
5898   } else {
5899     assert(n_par_threads() == 0,
5900            "Should be the original non-parallel value");
5901     n_workers = 1;
5902   }
5903 
5904   G1ParTask g1_par_task(this, _task_queues);
5905 
5906   init_for_evac_failure(NULL);
5907 
5908   rem_set()->prepare_for_younger_refs_iterate(true);
5909 
5910   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5911   double start_par_time_sec = os::elapsedTime();
5912   double end_par_time_sec;
5913 
5914   {
5915     StrongRootsScope srs(this);
5916     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5917     if (g1_policy()->during_initial_mark_pause()) {
5918       ClassLoaderDataGraph::clear_claimed_marks();
5919     }
5920 
5921     if (G1CollectedHeap::use_parallel_gc_threads()) {
5922       // The individual threads will set their evac-failure closures.
5923       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5924       // These tasks use ShareHeap::_process_strong_tasks
5925       assert(UseDynamicNumberOfGCThreads ||
5926              workers()->active_workers() == workers()->total_workers(),
5927              "If not dynamic should be using all the  workers");
5928       workers()->run_task(&g1_par_task);
5929     } else {
5930       g1_par_task.set_for_termination(n_workers);
5931       g1_par_task.work(0);
5932     }
5933     end_par_time_sec = os::elapsedTime();
5934 
5935     // Closing the inner scope will execute the destructor
5936     // for the StrongRootsScope object. We record the current
5937     // elapsed time before closing the scope so that time
5938     // taken for the SRS destructor is NOT included in the
5939     // reported parallel time.
5940   }
5941 
5942   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5943   g1_policy()->phase_times()->record_par_time(par_time_ms);
5944 
5945   double code_root_fixup_time_ms =
5946         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5947   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5948 
5949   set_par_threads(0);
5950 
5951   // Process any discovered reference objects - we have
5952   // to do this _before_ we retire the GC alloc regions
5953   // as we may have to copy some 'reachable' referent
5954   // objects (and their reachable sub-graphs) that were
5955   // not copied during the pause.
5956   process_discovered_references(n_workers);
5957 
5958   // Weak root processing.
5959   {
5960     G1STWIsAliveClosure is_alive(this);
5961     G1KeepAliveClosure keep_alive(this);
5962     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5963     if (G1StringDedup::is_enabled()) {
5964       G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5965     }
5966   }
5967 
5968   release_gc_alloc_regions(n_workers, evacuation_info);
5969   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5970 
5971   // Reset and re-enable the hot card cache.
5972   // Note the counts for the cards in the regions in the
5973   // collection set are reset when the collection set is freed.
5974   hot_card_cache->reset_hot_cache();
5975   hot_card_cache->set_use_cache(true);
5976 
5977   // Migrate the strong code roots attached to each region in
5978   // the collection set. Ideally we would like to do this
5979   // after we have finished the scanning/evacuation of the
5980   // strong code roots for a particular heap region.
5981   migrate_strong_code_roots();
5982 
5983   purge_code_root_memory();
5984 
5985   if (g1_policy()->during_initial_mark_pause()) {
5986     // Reset the claim values set during marking the strong code roots
5987     reset_heap_region_claim_values();
5988   }
5989 
5990   finalize_for_evac_failure();
5991 
5992   if (evacuation_failed()) {
5993     remove_self_forwarding_pointers();
5994 
5995     // Reset the G1EvacuationFailureALot counters and flags
5996     // Note: the values are reset only when an actual
5997     // evacuation failure occurs.
5998     NOT_PRODUCT(reset_evacuation_should_fail();)
5999   }
6000 
6001   // Enqueue any remaining references remaining on the STW
6002   // reference processor's discovered lists. We need to do
6003   // this after the card table is cleaned (and verified) as
6004   // the act of enqueueing entries on to the pending list
6005   // will log these updates (and dirty their associated
6006   // cards). We need these updates logged to update any
6007   // RSets.
6008   enqueue_discovered_references(n_workers);
6009 
6010   if (G1DeferredRSUpdate) {
6011     redirty_logged_cards();
6012   }
6013   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
6014 }
6015 
6016 void G1CollectedHeap::free_region(HeapRegion* hr,
6017                                   FreeRegionList* free_list,
6018                                   bool par,
6019                                   bool locked) {
6020   assert(!hr->isHumongous(), "this is only for non-humongous regions");
6021   assert(!hr->is_empty(), "the region should not be empty");
6022   assert(_hrs.is_available(hr->hrs_index()), "region should be committed");
6023   assert(free_list != NULL, "pre-condition");
6024 
6025   if (G1VerifyBitmaps) {
6026     MemRegion mr(hr->bottom(), hr->end());
6027     concurrent_mark()->clearRangePrevBitmap(mr);
6028   }
6029 
6030   // Clear the card counts for this region.
6031   // Note: we only need to do this if the region is not young
6032   // (since we don't refine cards in young regions).
6033   if (!hr->is_young()) {
6034     _cg1r->hot_card_cache()->reset_card_counts(hr);
6035   }
6036   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
6037   free_list->add_ordered(hr);
6038 }
6039 
6040 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
6041                                      FreeRegionList* free_list,
6042                                      bool par) {
6043   assert(hr->startsHumongous(), "this is only for starts humongous regions");
6044   assert(free_list != NULL, "pre-condition");
6045 
6046   size_t hr_capacity = hr->capacity();
6047   // We need to read this before we make the region non-humongous,
6048   // otherwise the information will be gone.
6049   uint last_index = hr->last_hc_index();
6050   hr->set_notHumongous();
6051   free_region(hr, free_list, par);
6052 
6053   uint i = hr->hrs_index() + 1;
6054   while (i < last_index) {
6055     HeapRegion* curr_hr = region_at(i);
6056     assert(curr_hr->continuesHumongous(), "invariant");
6057     curr_hr->set_notHumongous();
6058     free_region(curr_hr, free_list, par);
6059     i += 1;
6060   }
6061 }
6062 
6063 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6064                                        const HeapRegionSetCount& humongous_regions_removed) {
6065   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6066     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6067     _old_set.bulk_remove(old_regions_removed);
6068     _humongous_set.bulk_remove(humongous_regions_removed);
6069   }
6070 
6071 }
6072 
6073 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6074   assert(list != NULL, "list can't be null");
6075   if (!list->is_empty()) {
6076     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6077     _hrs.insert_list_into_free_list(list);
6078   }
6079 }
6080 
6081 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6082   assert(_summary_bytes_used >= bytes,
6083          err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6084                   _summary_bytes_used, bytes));
6085   _summary_bytes_used -= bytes;
6086 }
6087 
6088 class G1ParCleanupCTTask : public AbstractGangTask {
6089   G1SATBCardTableModRefBS* _ct_bs;
6090   G1CollectedHeap* _g1h;
6091   HeapRegion* volatile _su_head;
6092 public:
6093   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6094                      G1CollectedHeap* g1h) :
6095     AbstractGangTask("G1 Par Cleanup CT Task"),
6096     _ct_bs(ct_bs), _g1h(g1h) { }
6097 
6098   void work(uint worker_id) {
6099     HeapRegion* r;
6100     while (r = _g1h->pop_dirty_cards_region()) {
6101       clear_cards(r);
6102     }
6103   }
6104 
6105   void clear_cards(HeapRegion* r) {
6106     // Cards of the survivors should have already been dirtied.
6107     if (!r->is_survivor()) {
6108       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6109     }
6110   }
6111 };
6112 
6113 #ifndef PRODUCT
6114 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6115   G1CollectedHeap* _g1h;
6116   G1SATBCardTableModRefBS* _ct_bs;
6117 public:
6118   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6119     : _g1h(g1h), _ct_bs(ct_bs) { }
6120   virtual bool doHeapRegion(HeapRegion* r) {
6121     if (r->is_survivor()) {
6122       _g1h->verify_dirty_region(r);
6123     } else {
6124       _g1h->verify_not_dirty_region(r);
6125     }
6126     return false;
6127   }
6128 };
6129 
6130 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6131   // All of the region should be clean.
6132   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6133   MemRegion mr(hr->bottom(), hr->end());
6134   ct_bs->verify_not_dirty_region(mr);
6135 }
6136 
6137 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6138   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
6139   // dirty allocated blocks as they allocate them. The thread that
6140   // retires each region and replaces it with a new one will do a
6141   // maximal allocation to fill in [pre_dummy_top(),end()] but will
6142   // not dirty that area (one less thing to have to do while holding
6143   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6144   // is dirty.
6145   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6146   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6147   if (hr->is_young()) {
6148     ct_bs->verify_g1_young_region(mr);
6149   } else {
6150     ct_bs->verify_dirty_region(mr);
6151   }
6152 }
6153 
6154 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6155   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6156   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6157     verify_dirty_region(hr);
6158   }
6159 }
6160 
6161 void G1CollectedHeap::verify_dirty_young_regions() {
6162   verify_dirty_young_list(_young_list->first_region());
6163 }
6164 
6165 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6166                                                HeapWord* tams, HeapWord* end) {
6167   guarantee(tams <= end,
6168             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6169   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6170   if (result < end) {
6171     gclog_or_tty->cr();
6172     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6173                            bitmap_name, result);
6174     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6175                            bitmap_name, tams, end);
6176     return false;
6177   }
6178   return true;
6179 }
6180 
6181 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6182   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6183   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6184 
6185   HeapWord* bottom = hr->bottom();
6186   HeapWord* ptams  = hr->prev_top_at_mark_start();
6187   HeapWord* ntams  = hr->next_top_at_mark_start();
6188   HeapWord* end    = hr->end();
6189 
6190   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6191 
6192   bool res_n = true;
6193   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6194   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6195   // if we happen to be in that state.
6196   if (mark_in_progress() || !_cmThread->in_progress()) {
6197     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6198   }
6199   if (!res_p || !res_n) {
6200     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6201                            HR_FORMAT_PARAMS(hr));
6202     gclog_or_tty->print_cr("#### Caller: %s", caller);
6203     return false;
6204   }
6205   return true;
6206 }
6207 
6208 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6209   if (!G1VerifyBitmaps) return;
6210 
6211   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6212 }
6213 
6214 class G1VerifyBitmapClosure : public HeapRegionClosure {
6215 private:
6216   const char* _caller;
6217   G1CollectedHeap* _g1h;
6218   bool _failures;
6219 
6220 public:
6221   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6222     _caller(caller), _g1h(g1h), _failures(false) { }
6223 
6224   bool failures() { return _failures; }
6225 
6226   virtual bool doHeapRegion(HeapRegion* hr) {
6227     if (hr->continuesHumongous()) return false;
6228 
6229     bool result = _g1h->verify_bitmaps(_caller, hr);
6230     if (!result) {
6231       _failures = true;
6232     }
6233     return false;
6234   }
6235 };
6236 
6237 void G1CollectedHeap::check_bitmaps(const char* caller) {
6238   if (!G1VerifyBitmaps) return;
6239 
6240   G1VerifyBitmapClosure cl(caller, this);
6241   heap_region_iterate(&cl);
6242   guarantee(!cl.failures(), "bitmap verification");
6243 }
6244 #endif // PRODUCT
6245 
6246 void G1CollectedHeap::cleanUpCardTable() {
6247   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6248   double start = os::elapsedTime();
6249 
6250   {
6251     // Iterate over the dirty cards region list.
6252     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6253 
6254     if (G1CollectedHeap::use_parallel_gc_threads()) {
6255       set_par_threads();
6256       workers()->run_task(&cleanup_task);
6257       set_par_threads(0);
6258     } else {
6259       while (_dirty_cards_region_list) {
6260         HeapRegion* r = _dirty_cards_region_list;
6261         cleanup_task.clear_cards(r);
6262         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6263         if (_dirty_cards_region_list == r) {
6264           // The last region.
6265           _dirty_cards_region_list = NULL;
6266         }
6267         r->set_next_dirty_cards_region(NULL);
6268       }
6269     }
6270 #ifndef PRODUCT
6271     if (G1VerifyCTCleanup || VerifyAfterGC) {
6272       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6273       heap_region_iterate(&cleanup_verifier);
6274     }
6275 #endif
6276   }
6277 
6278   double elapsed = os::elapsedTime() - start;
6279   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6280 }
6281 
6282 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6283   size_t pre_used = 0;
6284   FreeRegionList local_free_list("Local List for CSet Freeing");
6285 
6286   double young_time_ms     = 0.0;
6287   double non_young_time_ms = 0.0;
6288 
6289   // Since the collection set is a superset of the the young list,
6290   // all we need to do to clear the young list is clear its
6291   // head and length, and unlink any young regions in the code below
6292   _young_list->clear();
6293 
6294   G1CollectorPolicy* policy = g1_policy();
6295 
6296   double start_sec = os::elapsedTime();
6297   bool non_young = true;
6298 
6299   HeapRegion* cur = cs_head;
6300   int age_bound = -1;
6301   size_t rs_lengths = 0;
6302 
6303   while (cur != NULL) {
6304     assert(!is_on_master_free_list(cur), "sanity");
6305     if (non_young) {
6306       if (cur->is_young()) {
6307         double end_sec = os::elapsedTime();
6308         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6309         non_young_time_ms += elapsed_ms;
6310 
6311         start_sec = os::elapsedTime();
6312         non_young = false;
6313       }
6314     } else {
6315       if (!cur->is_young()) {
6316         double end_sec = os::elapsedTime();
6317         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6318         young_time_ms += elapsed_ms;
6319 
6320         start_sec = os::elapsedTime();
6321         non_young = true;
6322       }
6323     }
6324 
6325     rs_lengths += cur->rem_set()->occupied_locked();
6326 
6327     HeapRegion* next = cur->next_in_collection_set();
6328     assert(cur->in_collection_set(), "bad CS");
6329     cur->set_next_in_collection_set(NULL);
6330     cur->set_in_collection_set(false);
6331 
6332     if (cur->is_young()) {
6333       int index = cur->young_index_in_cset();
6334       assert(index != -1, "invariant");
6335       assert((uint) index < policy->young_cset_region_length(), "invariant");
6336       size_t words_survived = _surviving_young_words[index];
6337       cur->record_surv_words_in_group(words_survived);
6338 
6339       // At this point the we have 'popped' cur from the collection set
6340       // (linked via next_in_collection_set()) but it is still in the
6341       // young list (linked via next_young_region()). Clear the
6342       // _next_young_region field.
6343       cur->set_next_young_region(NULL);
6344     } else {
6345       int index = cur->young_index_in_cset();
6346       assert(index == -1, "invariant");
6347     }
6348 
6349     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6350             (!cur->is_young() && cur->young_index_in_cset() == -1),
6351             "invariant" );
6352 
6353     if (!cur->evacuation_failed()) {
6354       MemRegion used_mr = cur->used_region();
6355 
6356       // And the region is empty.
6357       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6358       pre_used += cur->used();
6359       free_region(cur, &local_free_list, false /* par */, true /* locked */);
6360     } else {
6361       cur->uninstall_surv_rate_group();
6362       if (cur->is_young()) {
6363         cur->set_young_index_in_cset(-1);
6364       }
6365       cur->set_not_young();
6366       cur->set_evacuation_failed(false);
6367       // The region is now considered to be old.
6368       _old_set.add(cur);
6369       evacuation_info.increment_collectionset_used_after(cur->used());
6370     }
6371     cur = next;
6372   }
6373 
6374   evacuation_info.set_regions_freed(local_free_list.length());
6375   policy->record_max_rs_lengths(rs_lengths);
6376   policy->cset_regions_freed();
6377 
6378   double end_sec = os::elapsedTime();
6379   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6380 
6381   if (non_young) {
6382     non_young_time_ms += elapsed_ms;
6383   } else {
6384     young_time_ms += elapsed_ms;
6385   }
6386 
6387   prepend_to_freelist(&local_free_list);
6388   decrement_summary_bytes(pre_used);
6389   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6390   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6391 }
6392 
6393 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6394  private:
6395   FreeRegionList* _free_region_list;
6396   HeapRegionSet* _proxy_set;
6397   HeapRegionSetCount _humongous_regions_removed;
6398   size_t _freed_bytes;
6399  public:
6400 
6401   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6402     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6403   }
6404 
6405   virtual bool doHeapRegion(HeapRegion* r) {
6406     if (!r->startsHumongous()) {
6407       return false;
6408     }
6409 
6410     G1CollectedHeap* g1h = G1CollectedHeap::heap();
6411 
6412     oop obj = (oop)r->bottom();
6413     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6414 
6415     // The following checks whether the humongous object is live are sufficient.
6416     // The main additional check (in addition to having a reference from the roots
6417     // or the young gen) is whether the humongous object has a remembered set entry.
6418     //
6419     // A humongous object cannot be live if there is no remembered set for it
6420     // because:
6421     // - there can be no references from within humongous starts regions referencing
6422     // the object because we never allocate other objects into them.
6423     // (I.e. there are no intra-region references that may be missed by the
6424     // remembered set)
6425     // - as soon there is a remembered set entry to the humongous starts region
6426     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6427     // until the end of a concurrent mark.
6428     //
6429     // It is not required to check whether the object has been found dead by marking
6430     // or not, in fact it would prevent reclamation within a concurrent cycle, as
6431     // all objects allocated during that time are considered live.
6432     // SATB marking is even more conservative than the remembered set.
6433     // So if at this point in the collection there is no remembered set entry,
6434     // nobody has a reference to it.
6435     // At the start of collection we flush all refinement logs, and remembered sets
6436     // are completely up-to-date wrt to references to the humongous object.
6437     //
6438     // Other implementation considerations:
6439     // - never consider object arrays: while they are a valid target, they have not
6440     // been observed to be used as temporary objects.
6441     // - they would also pose considerable effort for cleaning up the the remembered
6442     // sets.
6443     // While this cleanup is not strictly necessary to be done (or done instantly),
6444     // given that their occurrence is very low, this saves us this additional
6445     // complexity.
6446     uint region_idx = r->hrs_index();
6447     if (g1h->humongous_is_live(region_idx) ||
6448         g1h->humongous_region_is_always_live(region_idx)) {
6449 
6450       if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6451         gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6452                                r->isHumongous(),
6453                                region_idx,
6454                                r->rem_set()->occupied(),
6455                                r->rem_set()->strong_code_roots_list_length(),
6456                                next_bitmap->isMarked(r->bottom()),
6457                                g1h->humongous_is_live(region_idx),
6458                                obj->is_objArray()
6459                               );
6460       }
6461 
6462       return false;
6463     }
6464 
6465     guarantee(!obj->is_objArray(),
6466               err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6467                       r->bottom()));
6468 
6469     if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6470       gclog_or_tty->print_cr("Reclaim humongous region %d start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6471                              r->isHumongous(),
6472                              r->bottom(),
6473                              region_idx,
6474                              r->region_num(),
6475                              r->rem_set()->occupied(),
6476                              r->rem_set()->strong_code_roots_list_length(),
6477                              next_bitmap->isMarked(r->bottom()),
6478                              g1h->humongous_is_live(region_idx),
6479                              obj->is_objArray()
6480                             );
6481     }
6482     // Need to clear mark bit of the humongous object if already set.
6483     if (next_bitmap->isMarked(r->bottom())) {
6484       next_bitmap->clear(r->bottom());
6485     }
6486     _freed_bytes += r->used();
6487     r->set_containing_set(NULL);
6488     _humongous_regions_removed.increment(1u, r->capacity());
6489     g1h->free_humongous_region(r, _free_region_list, false);
6490 
6491     return false;
6492   }
6493 
6494   HeapRegionSetCount& humongous_free_count() {
6495     return _humongous_regions_removed;
6496   }
6497 
6498   size_t bytes_freed() const {
6499     return _freed_bytes;
6500   }
6501 
6502   size_t humongous_reclaimed() const {
6503     return _humongous_regions_removed.length();
6504   }
6505 };
6506 
6507 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6508   assert_at_safepoint(true);
6509 
6510   if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) {
6511     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6512     return;
6513   }
6514 
6515   double start_time = os::elapsedTime();
6516 
6517   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6518 
6519   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6520   heap_region_iterate(&cl);
6521 
6522   HeapRegionSetCount empty_set;
6523   remove_from_old_sets(empty_set, cl.humongous_free_count());
6524 
6525   G1HRPrinter* hr_printer = _g1h->hr_printer();
6526   if (hr_printer->is_active()) {
6527     FreeRegionListIterator iter(&local_cleanup_list);
6528     while (iter.more_available()) {
6529       HeapRegion* hr = iter.get_next();
6530       hr_printer->cleanup(hr);
6531     }
6532   }
6533 
6534   prepend_to_freelist(&local_cleanup_list);
6535   decrement_summary_bytes(cl.bytes_freed());
6536 
6537   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6538                                                                     cl.humongous_reclaimed());
6539 }
6540 
6541 // This routine is similar to the above but does not record
6542 // any policy statistics or update free lists; we are abandoning
6543 // the current incremental collection set in preparation of a
6544 // full collection. After the full GC we will start to build up
6545 // the incremental collection set again.
6546 // This is only called when we're doing a full collection
6547 // and is immediately followed by the tearing down of the young list.
6548 
6549 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6550   HeapRegion* cur = cs_head;
6551 
6552   while (cur != NULL) {
6553     HeapRegion* next = cur->next_in_collection_set();
6554     assert(cur->in_collection_set(), "bad CS");
6555     cur->set_next_in_collection_set(NULL);
6556     cur->set_in_collection_set(false);
6557     cur->set_young_index_in_cset(-1);
6558     cur = next;
6559   }
6560 }
6561 
6562 void G1CollectedHeap::set_free_regions_coming() {
6563   if (G1ConcRegionFreeingVerbose) {
6564     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6565                            "setting free regions coming");
6566   }
6567 
6568   assert(!free_regions_coming(), "pre-condition");
6569   _free_regions_coming = true;
6570 }
6571 
6572 void G1CollectedHeap::reset_free_regions_coming() {
6573   assert(free_regions_coming(), "pre-condition");
6574 
6575   {
6576     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6577     _free_regions_coming = false;
6578     SecondaryFreeList_lock->notify_all();
6579   }
6580 
6581   if (G1ConcRegionFreeingVerbose) {
6582     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6583                            "reset free regions coming");
6584   }
6585 }
6586 
6587 void G1CollectedHeap::wait_while_free_regions_coming() {
6588   // Most of the time we won't have to wait, so let's do a quick test
6589   // first before we take the lock.
6590   if (!free_regions_coming()) {
6591     return;
6592   }
6593 
6594   if (G1ConcRegionFreeingVerbose) {
6595     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6596                            "waiting for free regions");
6597   }
6598 
6599   {
6600     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6601     while (free_regions_coming()) {
6602       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6603     }
6604   }
6605 
6606   if (G1ConcRegionFreeingVerbose) {
6607     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6608                            "done waiting for free regions");
6609   }
6610 }
6611 
6612 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6613   assert(heap_lock_held_for_gc(),
6614               "the heap lock should already be held by or for this thread");
6615   _young_list->push_region(hr);
6616 }
6617 
6618 class NoYoungRegionsClosure: public HeapRegionClosure {
6619 private:
6620   bool _success;
6621 public:
6622   NoYoungRegionsClosure() : _success(true) { }
6623   bool doHeapRegion(HeapRegion* r) {
6624     if (r->is_young()) {
6625       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6626                              r->bottom(), r->end());
6627       _success = false;
6628     }
6629     return false;
6630   }
6631   bool success() { return _success; }
6632 };
6633 
6634 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6635   bool ret = _young_list->check_list_empty(check_sample);
6636 
6637   if (check_heap) {
6638     NoYoungRegionsClosure closure;
6639     heap_region_iterate(&closure);
6640     ret = ret && closure.success();
6641   }
6642 
6643   return ret;
6644 }
6645 
6646 class TearDownRegionSetsClosure : public HeapRegionClosure {
6647 private:
6648   HeapRegionSet *_old_set;
6649 
6650 public:
6651   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6652 
6653   bool doHeapRegion(HeapRegion* r) {
6654     if (r->is_empty()) {
6655       // We ignore empty regions, we'll empty the free list afterwards
6656     } else if (r->is_young()) {
6657       // We ignore young regions, we'll empty the young list afterwards
6658     } else if (r->isHumongous()) {
6659       // We ignore humongous regions, we're not tearing down the
6660       // humongous region set
6661     } else {
6662       // The rest should be old
6663       _old_set->remove(r);
6664     }
6665     return false;
6666   }
6667 
6668   ~TearDownRegionSetsClosure() {
6669     assert(_old_set->is_empty(), "post-condition");
6670   }
6671 };
6672 
6673 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6674   assert_at_safepoint(true /* should_be_vm_thread */);
6675 
6676   if (!free_list_only) {
6677     TearDownRegionSetsClosure cl(&_old_set);
6678     heap_region_iterate(&cl);
6679 
6680     // Note that emptying the _young_list is postponed and instead done as
6681     // the first step when rebuilding the regions sets again. The reason for
6682     // this is that during a full GC string deduplication needs to know if
6683     // a collected region was young or old when the full GC was initiated.
6684   }
6685   _hrs.remove_all_free_regions();
6686 }
6687 
6688 class RebuildRegionSetsClosure : public HeapRegionClosure {
6689 private:
6690   bool            _free_list_only;
6691   HeapRegionSet*   _old_set;
6692   HeapRegionSeq*   _hrs;
6693   size_t          _total_used;
6694 
6695 public:
6696   RebuildRegionSetsClosure(bool free_list_only,
6697                            HeapRegionSet* old_set, HeapRegionSeq* hrs) :
6698     _free_list_only(free_list_only),
6699     _old_set(old_set), _hrs(hrs), _total_used(0) {
6700     assert(_hrs->num_free_regions() == 0, "pre-condition");
6701     if (!free_list_only) {
6702       assert(_old_set->is_empty(), "pre-condition");
6703     }
6704   }
6705 
6706   bool doHeapRegion(HeapRegion* r) {
6707     if (r->continuesHumongous()) {
6708       return false;
6709     }
6710 
6711     if (r->is_empty()) {
6712       // Add free regions to the free list
6713       _hrs->insert_into_free_list(r);
6714     } else if (!_free_list_only) {
6715       assert(!r->is_young(), "we should not come across young regions");
6716 
6717       if (r->isHumongous()) {
6718         // We ignore humongous regions, we left the humongous set unchanged
6719       } else {
6720         // The rest should be old, add them to the old set
6721         _old_set->add(r);
6722       }
6723       _total_used += r->used();
6724     }
6725 
6726     return false;
6727   }
6728 
6729   size_t total_used() {
6730     return _total_used;
6731   }
6732 };
6733 
6734 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6735   assert_at_safepoint(true /* should_be_vm_thread */);
6736 
6737   if (!free_list_only) {
6738     _young_list->empty_list();
6739   }
6740 
6741   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrs);
6742   heap_region_iterate(&cl);
6743 
6744   if (!free_list_only) {
6745     _summary_bytes_used = cl.total_used();
6746   }
6747   assert(_summary_bytes_used == recalculate_used(),
6748          err_msg("inconsistent _summary_bytes_used, "
6749                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6750                  _summary_bytes_used, recalculate_used()));
6751 }
6752 
6753 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6754   _refine_cte_cl->set_concurrent(concurrent);
6755 }
6756 
6757 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6758   HeapRegion* hr = heap_region_containing(p);
6759   return hr->is_in(p);
6760 }
6761 
6762 // Methods for the mutator alloc region
6763 
6764 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6765                                                       bool force) {
6766   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6767   assert(!force || g1_policy()->can_expand_young_list(),
6768          "if force is true we should be able to expand the young list");
6769   bool young_list_full = g1_policy()->is_young_list_full();
6770   if (force || !young_list_full) {
6771     HeapRegion* new_alloc_region = new_region(word_size,
6772                                               false /* is_old */,
6773                                               false /* do_expand */);
6774     if (new_alloc_region != NULL) {
6775       set_region_short_lived_locked(new_alloc_region);
6776       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6777       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6778       return new_alloc_region;
6779     }
6780   }
6781   return NULL;
6782 }
6783 
6784 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6785                                                   size_t allocated_bytes) {
6786   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6787   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6788 
6789   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6790   _summary_bytes_used += allocated_bytes;
6791   _hr_printer.retire(alloc_region);
6792   // We update the eden sizes here, when the region is retired,
6793   // instead of when it's allocated, since this is the point that its
6794   // used space has been recored in _summary_bytes_used.
6795   g1mm()->update_eden_size();
6796 }
6797 
6798 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6799                                                     bool force) {
6800   return _g1h->new_mutator_alloc_region(word_size, force);
6801 }
6802 
6803 void G1CollectedHeap::set_par_threads() {
6804   // Don't change the number of workers.  Use the value previously set
6805   // in the workgroup.
6806   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6807   uint n_workers = workers()->active_workers();
6808   assert(UseDynamicNumberOfGCThreads ||
6809            n_workers == workers()->total_workers(),
6810       "Otherwise should be using the total number of workers");
6811   if (n_workers == 0) {
6812     assert(false, "Should have been set in prior evacuation pause.");
6813     n_workers = ParallelGCThreads;
6814     workers()->set_active_workers(n_workers);
6815   }
6816   set_par_threads(n_workers);
6817 }
6818 
6819 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6820                                        size_t allocated_bytes) {
6821   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6822 }
6823 
6824 // Methods for the GC alloc regions
6825 
6826 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6827                                                  uint count,
6828                                                  GCAllocPurpose ap) {
6829   assert(FreeList_lock->owned_by_self(), "pre-condition");
6830 
6831   if (count < g1_policy()->max_regions(ap)) {
6832     bool survivor = (ap == GCAllocForSurvived);
6833     HeapRegion* new_alloc_region = new_region(word_size,
6834                                               !survivor,
6835                                               true /* do_expand */);
6836     if (new_alloc_region != NULL) {
6837       // We really only need to do this for old regions given that we
6838       // should never scan survivors. But it doesn't hurt to do it
6839       // for survivors too.
6840       new_alloc_region->record_top_and_timestamp();
6841       if (survivor) {
6842         new_alloc_region->set_survivor();
6843         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6844         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6845       } else {
6846         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6847         check_bitmaps("Old Region Allocation", new_alloc_region);
6848       }
6849       bool during_im = g1_policy()->during_initial_mark_pause();
6850       new_alloc_region->note_start_of_copying(during_im);
6851       return new_alloc_region;
6852     } else {
6853       g1_policy()->note_alloc_region_limit_reached(ap);
6854     }
6855   }
6856   return NULL;
6857 }
6858 
6859 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6860                                              size_t allocated_bytes,
6861                                              GCAllocPurpose ap) {
6862   bool during_im = g1_policy()->during_initial_mark_pause();
6863   alloc_region->note_end_of_copying(during_im);
6864   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6865   if (ap == GCAllocForSurvived) {
6866     young_list()->add_survivor_region(alloc_region);
6867   } else {
6868     _old_set.add(alloc_region);
6869   }
6870   _hr_printer.retire(alloc_region);
6871 }
6872 
6873 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6874                                                        bool force) {
6875   assert(!force, "not supported for GC alloc regions");
6876   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6877 }
6878 
6879 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6880                                           size_t allocated_bytes) {
6881   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6882                                GCAllocForSurvived);
6883 }
6884 
6885 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6886                                                   bool force) {
6887   assert(!force, "not supported for GC alloc regions");
6888   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6889 }
6890 
6891 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6892                                      size_t allocated_bytes) {
6893   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6894                                GCAllocForTenured);
6895 }
6896 
6897 HeapRegion* OldGCAllocRegion::release() {
6898   HeapRegion* cur = get();
6899   if (cur != NULL) {
6900     // Determine how far we are from the next card boundary. If it is smaller than
6901     // the minimum object size we can allocate into, expand into the next card.
6902     HeapWord* top = cur->top();
6903     HeapWord* aligned_top = (HeapWord*)align_ptr_up(top, G1BlockOffsetSharedArray::N_bytes);
6904 
6905     size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);
6906 
6907     if (to_allocate_words != 0) {
6908       // We are not at a card boundary. Fill up, possibly into the next, taking the
6909       // end of the region and the minimum object size into account.
6910       to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
6911                                MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));
6912 
6913       // Skip allocation if there is not enough space to allocate even the smallest
6914       // possible object. In this case this region will not be retained, so the
6915       // original problem cannot occur.
6916       if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
6917         HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */);
6918         CollectedHeap::fill_with_object(dummy, to_allocate_words);
6919       }
6920     }
6921   }
6922   return G1AllocRegion::release();
6923 }
6924 
6925 // Heap region set verification
6926 
6927 class VerifyRegionListsClosure : public HeapRegionClosure {
6928 private:
6929   HeapRegionSet*   _old_set;
6930   HeapRegionSet*   _humongous_set;
6931   HeapRegionSeq*   _hrs;
6932 
6933 public:
6934   HeapRegionSetCount _old_count;
6935   HeapRegionSetCount _humongous_count;
6936   HeapRegionSetCount _free_count;
6937 
6938   VerifyRegionListsClosure(HeapRegionSet* old_set,
6939                            HeapRegionSet* humongous_set,
6940                            HeapRegionSeq* hrs) :
6941     _old_set(old_set), _humongous_set(humongous_set), _hrs(hrs),
6942     _old_count(), _humongous_count(), _free_count(){ }
6943 
6944   bool doHeapRegion(HeapRegion* hr) {
6945     if (hr->continuesHumongous()) {
6946       return false;
6947     }
6948 
6949     if (hr->is_young()) {
6950       // TODO
6951     } else if (hr->startsHumongous()) {
6952       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6953       _humongous_count.increment(1u, hr->capacity());
6954     } else if (hr->is_empty()) {
6955       assert(_hrs->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6956       _free_count.increment(1u, hr->capacity());
6957     } else {
6958       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6959       _old_count.increment(1u, hr->capacity());
6960     }
6961     return false;
6962   }
6963 
6964   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionSeq* free_list) {
6965     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6966     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6967         old_set->total_capacity_bytes(), _old_count.capacity()));
6968 
6969     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6970     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6971         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6972 
6973     guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
6974     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6975         free_list->total_capacity_bytes(), _free_count.capacity()));
6976   }
6977 };
6978 
6979 void G1CollectedHeap::verify_region_sets() {
6980   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6981 
6982   // First, check the explicit lists.
6983   _hrs.verify();
6984   {
6985     // Given that a concurrent operation might be adding regions to
6986     // the secondary free list we have to take the lock before
6987     // verifying it.
6988     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6989     _secondary_free_list.verify_list();
6990   }
6991 
6992   // If a concurrent region freeing operation is in progress it will
6993   // be difficult to correctly attributed any free regions we come
6994   // across to the correct free list given that they might belong to
6995   // one of several (free_list, secondary_free_list, any local lists,
6996   // etc.). So, if that's the case we will skip the rest of the
6997   // verification operation. Alternatively, waiting for the concurrent
6998   // operation to complete will have a non-trivial effect on the GC's
6999   // operation (no concurrent operation will last longer than the
7000   // interval between two calls to verification) and it might hide
7001   // any issues that we would like to catch during testing.
7002   if (free_regions_coming()) {
7003     return;
7004   }
7005 
7006   // Make sure we append the secondary_free_list on the free_list so
7007   // that all free regions we will come across can be safely
7008   // attributed to the free_list.
7009   append_secondary_free_list_if_not_empty_with_lock();
7010 
7011   // Finally, make sure that the region accounting in the lists is
7012   // consistent with what we see in the heap.
7013 
7014   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrs);
7015   heap_region_iterate(&cl);
7016   cl.verify_counts(&_old_set, &_humongous_set, &_hrs);
7017 }
7018 
7019 // Optimized nmethod scanning
7020 
7021 class RegisterNMethodOopClosure: public OopClosure {
7022   G1CollectedHeap* _g1h;
7023   nmethod* _nm;
7024 
7025   template <class T> void do_oop_work(T* p) {
7026     T heap_oop = oopDesc::load_heap_oop(p);
7027     if (!oopDesc::is_null(heap_oop)) {
7028       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
7029       HeapRegion* hr = _g1h->heap_region_containing(obj);
7030       assert(!hr->continuesHumongous(),
7031              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
7032                      " starting at "HR_FORMAT,
7033                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
7034 
7035       // HeapRegion::add_strong_code_root() avoids adding duplicate
7036       // entries but having duplicates is  OK since we "mark" nmethods
7037       // as visited when we scan the strong code root lists during the GC.
7038       hr->add_strong_code_root(_nm);
7039       assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
7040              err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
7041                      _nm, HR_FORMAT_PARAMS(hr)));
7042     }
7043   }
7044 
7045 public:
7046   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
7047     _g1h(g1h), _nm(nm) {}
7048 
7049   void do_oop(oop* p)       { do_oop_work(p); }
7050   void do_oop(narrowOop* p) { do_oop_work(p); }
7051 };
7052 
7053 class UnregisterNMethodOopClosure: public OopClosure {
7054   G1CollectedHeap* _g1h;
7055   nmethod* _nm;
7056 
7057   template <class T> void do_oop_work(T* p) {
7058     T heap_oop = oopDesc::load_heap_oop(p);
7059     if (!oopDesc::is_null(heap_oop)) {
7060       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
7061       HeapRegion* hr = _g1h->heap_region_containing(obj);
7062       assert(!hr->continuesHumongous(),
7063              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
7064                      " starting at "HR_FORMAT,
7065                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
7066 
7067       hr->remove_strong_code_root(_nm);
7068       assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
7069              err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
7070                      _nm, HR_FORMAT_PARAMS(hr)));
7071     }
7072   }
7073 
7074 public:
7075   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
7076     _g1h(g1h), _nm(nm) {}
7077 
7078   void do_oop(oop* p)       { do_oop_work(p); }
7079   void do_oop(narrowOop* p) { do_oop_work(p); }
7080 };
7081 
7082 void G1CollectedHeap::register_nmethod(nmethod* nm) {
7083   CollectedHeap::register_nmethod(nm);
7084 
7085   guarantee(nm != NULL, "sanity");
7086   RegisterNMethodOopClosure reg_cl(this, nm);
7087   nm->oops_do(&reg_cl);
7088 }
7089 
7090 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
7091   CollectedHeap::unregister_nmethod(nm);
7092 
7093   guarantee(nm != NULL, "sanity");
7094   UnregisterNMethodOopClosure reg_cl(this, nm);
7095   nm->oops_do(&reg_cl, true);
7096 }
7097 
7098 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
7099 public:
7100   bool doHeapRegion(HeapRegion *hr) {
7101     assert(!hr->isHumongous(),
7102            err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
7103                    HR_FORMAT_PARAMS(hr)));
7104     hr->migrate_strong_code_roots();
7105     return false;
7106   }
7107 };
7108 
7109 void G1CollectedHeap::migrate_strong_code_roots() {
7110   MigrateCodeRootsHeapRegionClosure cl;
7111   double migrate_start = os::elapsedTime();
7112   collection_set_iterate(&cl);
7113   double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
7114   g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
7115 }
7116 
7117 void G1CollectedHeap::purge_code_root_memory() {
7118   double purge_start = os::elapsedTime();
7119   G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
7120   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
7121   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
7122 }
7123 
7124 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
7125   G1CollectedHeap* _g1h;
7126 
7127 public:
7128   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7129     _g1h(g1h) {}
7130 
7131   void do_code_blob(CodeBlob* cb) {
7132     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7133     if (nm == NULL) {
7134       return;
7135     }
7136 
7137     if (ScavengeRootsInCode) {
7138       _g1h->register_nmethod(nm);
7139     }
7140   }
7141 };
7142 
7143 void G1CollectedHeap::rebuild_strong_code_roots() {
7144   RebuildStrongCodeRootClosure blob_cl(this);
7145   CodeCache::blobs_do(&blob_cl);
7146 }