1 /*
   2  * Copyright (c) 2001, 2015, 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 "classfile/metadataOnStackMark.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "code/icBuffer.hpp"
  33 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  34 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  35 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  36 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  37 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  38 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  39 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  40 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  41 #include "gc_implementation/g1/g1EvacFailure.hpp"
  42 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  43 #include "gc_implementation/g1/g1Log.hpp"
  44 #include "gc_implementation/g1/g1MarkSweep.hpp"
  45 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  46 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
  47 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
  48 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  49 #include "gc_implementation/g1/g1RootProcessor.hpp"
  50 #include "gc_implementation/g1/g1StringDedup.hpp"
  51 #include "gc_implementation/g1/g1YCTypes.hpp"
  52 #include "gc_implementation/g1/heapRegion.inline.hpp"
  53 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  54 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
  55 #include "gc_implementation/g1/vm_operations_g1.hpp"
  56 #include "gc_implementation/shared/gcHeapSummary.hpp"
  57 #include "gc_implementation/shared/gcTimer.hpp"
  58 #include "gc_implementation/shared/gcTrace.hpp"
  59 #include "gc_implementation/shared/gcTraceTime.hpp"
  60 #include "gc_implementation/shared/isGCActiveMark.hpp"
  61 #include "memory/allocation.hpp"
  62 #include "memory/gcLocker.inline.hpp"
  63 #include "memory/generationSpec.hpp"
  64 #include "memory/iterator.hpp"
  65 #include "memory/referenceProcessor.hpp"
  66 #include "oops/oop.inline.hpp"
  67 #include "oops/oop.pcgc.inline.hpp"
  68 #include "runtime/orderAccess.inline.hpp"
  69 #include "runtime/vmThread.hpp"
  70 
  71 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  72 
  73 // turn it on so that the contents of the young list (scan-only /
  74 // to-be-collected) are printed at "strategic" points before / during
  75 // / after the collection --- this is useful for debugging
  76 #define YOUNG_LIST_VERBOSE 0
  77 // CURRENT STATUS
  78 // This file is under construction.  Search for "FIXME".
  79 
  80 // INVARIANTS/NOTES
  81 //
  82 // All allocation activity covered by the G1CollectedHeap interface is
  83 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  84 // and allocate_new_tlab, which are the "entry" points to the
  85 // allocation code from the rest of the JVM.  (Note that this does not
  86 // apply to TLAB allocation, which is not part of this interface: it
  87 // is done by clients of this interface.)
  88 
  89 // Local to this file.
  90 
  91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  92   bool _concurrent;
  93 public:
  94   RefineCardTableEntryClosure() : _concurrent(true) { }
  95 
  96   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  97     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
  98     // This path is executed by the concurrent refine or mutator threads,
  99     // concurrently, and so we do not care if card_ptr contains references
 100     // that point into the collection set.
 101     assert(!oops_into_cset, "should be");
 102 
 103     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 104       // Caller will actually yield.
 105       return false;
 106     }
 107     // Otherwise, we finished successfully; return true.
 108     return true;
 109   }
 110 
 111   void set_concurrent(bool b) { _concurrent = b; }
 112 };
 113 
 114 
 115 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 116   size_t _num_processed;
 117   CardTableModRefBS* _ctbs;
 118   int _histo[256];
 119 
 120  public:
 121   ClearLoggedCardTableEntryClosure() :
 122     _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
 123   {
 124     for (int i = 0; i < 256; i++) _histo[i] = 0;
 125   }
 126 
 127   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 128     unsigned char* ujb = (unsigned char*)card_ptr;
 129     int ind = (int)(*ujb);
 130     _histo[ind]++;
 131 
 132     *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
 133     _num_processed++;
 134 
 135     return true;
 136   }
 137 
 138   size_t num_processed() { return _num_processed; }
 139 
 140   void print_histo() {
 141     gclog_or_tty->print_cr("Card table value histogram:");
 142     for (int i = 0; i < 256; i++) {
 143       if (_histo[i] != 0) {
 144         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 145       }
 146     }
 147   }
 148 };
 149 
 150 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 151  private:
 152   size_t _num_processed;
 153 
 154  public:
 155   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 156 
 157   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 158     *card_ptr = CardTableModRefBS::dirty_card_val();
 159     _num_processed++;
 160     return true;
 161   }
 162 
 163   size_t num_processed() const { return _num_processed; }
 164 };
 165 
 166 YoungList::YoungList(G1CollectedHeap* g1h) :
 167     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 168     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 169   guarantee(check_list_empty(false), "just making sure...");
 170 }
 171 
 172 void YoungList::push_region(HeapRegion *hr) {
 173   assert(!hr->is_young(), "should not already be young");
 174   assert(hr->get_next_young_region() == NULL, "cause it should!");
 175 
 176   hr->set_next_young_region(_head);
 177   _head = hr;
 178 
 179   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 180   ++_length;
 181 }
 182 
 183 void YoungList::add_survivor_region(HeapRegion* hr) {
 184   assert(hr->is_survivor(), "should be flagged as survivor region");
 185   assert(hr->get_next_young_region() == NULL, "cause it should!");
 186 
 187   hr->set_next_young_region(_survivor_head);
 188   if (_survivor_head == NULL) {
 189     _survivor_tail = hr;
 190   }
 191   _survivor_head = hr;
 192   ++_survivor_length;
 193 }
 194 
 195 void YoungList::empty_list(HeapRegion* list) {
 196   while (list != NULL) {
 197     HeapRegion* next = list->get_next_young_region();
 198     list->set_next_young_region(NULL);
 199     list->uninstall_surv_rate_group();
 200     // This is called before a Full GC and all the non-empty /
 201     // non-humongous regions at the end of the Full GC will end up as
 202     // old anyway.
 203     list->set_old();
 204     list = next;
 205   }
 206 }
 207 
 208 void YoungList::empty_list() {
 209   assert(check_list_well_formed(), "young list should be well formed");
 210 
 211   empty_list(_head);
 212   _head = NULL;
 213   _length = 0;
 214 
 215   empty_list(_survivor_head);
 216   _survivor_head = NULL;
 217   _survivor_tail = NULL;
 218   _survivor_length = 0;
 219 
 220   _last_sampled_rs_lengths = 0;
 221 
 222   assert(check_list_empty(false), "just making sure...");
 223 }
 224 
 225 bool YoungList::check_list_well_formed() {
 226   bool ret = true;
 227 
 228   uint length = 0;
 229   HeapRegion* curr = _head;
 230   HeapRegion* last = NULL;
 231   while (curr != NULL) {
 232     if (!curr->is_young()) {
 233       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 234                              "incorrectly tagged (y: %d, surv: %d)",
 235                              curr->bottom(), curr->end(),
 236                              curr->is_young(), curr->is_survivor());
 237       ret = false;
 238     }
 239     ++length;
 240     last = curr;
 241     curr = curr->get_next_young_region();
 242   }
 243   ret = ret && (length == _length);
 244 
 245   if (!ret) {
 246     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 247     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 248                            length, _length);
 249   }
 250 
 251   return ret;
 252 }
 253 
 254 bool YoungList::check_list_empty(bool check_sample) {
 255   bool ret = true;
 256 
 257   if (_length != 0) {
 258     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 259                   _length);
 260     ret = false;
 261   }
 262   if (check_sample && _last_sampled_rs_lengths != 0) {
 263     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 264     ret = false;
 265   }
 266   if (_head != NULL) {
 267     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 268     ret = false;
 269   }
 270   if (!ret) {
 271     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 272   }
 273 
 274   return ret;
 275 }
 276 
 277 void
 278 YoungList::rs_length_sampling_init() {
 279   _sampled_rs_lengths = 0;
 280   _curr               = _head;
 281 }
 282 
 283 bool
 284 YoungList::rs_length_sampling_more() {
 285   return _curr != NULL;
 286 }
 287 
 288 void
 289 YoungList::rs_length_sampling_next() {
 290   assert( _curr != NULL, "invariant" );
 291   size_t rs_length = _curr->rem_set()->occupied();
 292 
 293   _sampled_rs_lengths += rs_length;
 294 
 295   // The current region may not yet have been added to the
 296   // incremental collection set (it gets added when it is
 297   // retired as the current allocation region).
 298   if (_curr->in_collection_set()) {
 299     // Update the collection set policy information for this region
 300     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 301   }
 302 
 303   _curr = _curr->get_next_young_region();
 304   if (_curr == NULL) {
 305     _last_sampled_rs_lengths = _sampled_rs_lengths;
 306     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 307   }
 308 }
 309 
 310 void
 311 YoungList::reset_auxilary_lists() {
 312   guarantee( is_empty(), "young list should be empty" );
 313   assert(check_list_well_formed(), "young list should be well formed");
 314 
 315   // Add survivor regions to SurvRateGroup.
 316   _g1h->g1_policy()->note_start_adding_survivor_regions();
 317   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 318 
 319   int young_index_in_cset = 0;
 320   for (HeapRegion* curr = _survivor_head;
 321        curr != NULL;
 322        curr = curr->get_next_young_region()) {
 323     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 324 
 325     // The region is a non-empty survivor so let's add it to
 326     // the incremental collection set for the next evacuation
 327     // pause.
 328     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 329     young_index_in_cset += 1;
 330   }
 331   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 332   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 333 
 334   _head   = _survivor_head;
 335   _length = _survivor_length;
 336   if (_survivor_head != NULL) {
 337     assert(_survivor_tail != NULL, "cause it shouldn't be");
 338     assert(_survivor_length > 0, "invariant");
 339     _survivor_tail->set_next_young_region(NULL);
 340   }
 341 
 342   // Don't clear the survivor list handles until the start of
 343   // the next evacuation pause - we need it in order to re-tag
 344   // the survivor regions from this evacuation pause as 'young'
 345   // at the start of the next.
 346 
 347   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 348 
 349   assert(check_list_well_formed(), "young list should be well formed");
 350 }
 351 
 352 void YoungList::print() {
 353   HeapRegion* lists[] = {_head,   _survivor_head};
 354   const char* names[] = {"YOUNG", "SURVIVOR"};
 355 
 356   for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
 357     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 358     HeapRegion *curr = lists[list];
 359     if (curr == NULL)
 360       gclog_or_tty->print_cr("  empty");
 361     while (curr != NULL) {
 362       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
 363                              HR_FORMAT_PARAMS(curr),
 364                              curr->prev_top_at_mark_start(),
 365                              curr->next_top_at_mark_start(),
 366                              curr->age_in_surv_rate_group_cond());
 367       curr = curr->get_next_young_region();
 368     }
 369   }
 370 
 371   gclog_or_tty->cr();
 372 }
 373 
 374 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 375   OtherRegionsTable::invalidate(start_idx, num_regions);
 376 }
 377 
 378 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 379   // The from card cache is not the memory that is actually committed. So we cannot
 380   // take advantage of the zero_filled parameter.
 381   reset_from_card_cache(start_idx, num_regions);
 382 }
 383 
 384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 385 {
 386   // Claim the right to put the region on the dirty cards region list
 387   // by installing a self pointer.
 388   HeapRegion* next = hr->get_next_dirty_cards_region();
 389   if (next == NULL) {
 390     HeapRegion* res = (HeapRegion*)
 391       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 392                           NULL);
 393     if (res == NULL) {
 394       HeapRegion* head;
 395       do {
 396         // Put the region to the dirty cards region list.
 397         head = _dirty_cards_region_list;
 398         next = (HeapRegion*)
 399           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 400         if (next == head) {
 401           assert(hr->get_next_dirty_cards_region() == hr,
 402                  "hr->get_next_dirty_cards_region() != hr");
 403           if (next == NULL) {
 404             // The last region in the list points to itself.
 405             hr->set_next_dirty_cards_region(hr);
 406           } else {
 407             hr->set_next_dirty_cards_region(next);
 408           }
 409         }
 410       } while (next != head);
 411     }
 412   }
 413 }
 414 
 415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 416 {
 417   HeapRegion* head;
 418   HeapRegion* hr;
 419   do {
 420     head = _dirty_cards_region_list;
 421     if (head == NULL) {
 422       return NULL;
 423     }
 424     HeapRegion* new_head = head->get_next_dirty_cards_region();
 425     if (head == new_head) {
 426       // The last region.
 427       new_head = NULL;
 428     }
 429     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 430                                           head);
 431   } while (hr != head);
 432   assert(hr != NULL, "invariant");
 433   hr->set_next_dirty_cards_region(NULL);
 434   return hr;
 435 }
 436 
 437 #ifdef ASSERT
 438 // A region is added to the collection set as it is retired
 439 // so an address p can point to a region which will be in the
 440 // collection set but has not yet been retired.  This method
 441 // therefore is only accurate during a GC pause after all
 442 // regions have been retired.  It is used for debugging
 443 // to check if an nmethod has references to objects that can
 444 // be move during a partial collection.  Though it can be
 445 // inaccurate, it is sufficient for G1 because the conservative
 446 // implementation of is_scavengable() for G1 will indicate that
 447 // all nmethods must be scanned during a partial collection.
 448 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 449   if (p == NULL) {
 450     return false;
 451   }
 452   return heap_region_containing(p)->in_collection_set();
 453 }
 454 #endif
 455 
 456 // Returns true if the reference points to an object that
 457 // can move in an incremental collection.
 458 bool G1CollectedHeap::is_scavengable(const void* p) {
 459   HeapRegion* hr = heap_region_containing(p);
 460   return !hr->isHumongous();
 461 }
 462 
 463 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 464   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 465   CardTableModRefBS* ct_bs = g1_barrier_set();
 466 
 467   // Count the dirty cards at the start.
 468   CountNonCleanMemRegionClosure count1(this);
 469   ct_bs->mod_card_iterate(&count1);
 470   int orig_count = count1.n();
 471 
 472   // First clear the logged cards.
 473   ClearLoggedCardTableEntryClosure clear;
 474   dcqs.apply_closure_to_all_completed_buffers(&clear);
 475   dcqs.iterate_closure_all_threads(&clear, false);
 476   clear.print_histo();
 477 
 478   // Now ensure that there's no dirty cards.
 479   CountNonCleanMemRegionClosure count2(this);
 480   ct_bs->mod_card_iterate(&count2);
 481   if (count2.n() != 0) {
 482     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 483                            count2.n(), orig_count);
 484   }
 485   guarantee(count2.n() == 0, "Card table should be clean.");
 486 
 487   RedirtyLoggedCardTableEntryClosure redirty;
 488   dcqs.apply_closure_to_all_completed_buffers(&redirty);
 489   dcqs.iterate_closure_all_threads(&redirty, false);
 490   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 491                          clear.num_processed(), orig_count);
 492   guarantee(redirty.num_processed() == clear.num_processed(),
 493             err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
 494                     redirty.num_processed(), clear.num_processed()));
 495 
 496   CountNonCleanMemRegionClosure count3(this);
 497   ct_bs->mod_card_iterate(&count3);
 498   if (count3.n() != orig_count) {
 499     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 500                            orig_count, count3.n());
 501     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 502   }
 503 }
 504 
 505 // Private class members.
 506 
 507 G1CollectedHeap* G1CollectedHeap::_g1h;
 508 
 509 // Private methods.
 510 
 511 HeapRegion*
 512 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 513   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 514   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 515     if (!_secondary_free_list.is_empty()) {
 516       if (G1ConcRegionFreeingVerbose) {
 517         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 518                                "secondary_free_list has %u entries",
 519                                _secondary_free_list.length());
 520       }
 521       // It looks as if there are free regions available on the
 522       // secondary_free_list. Let's move them to the free_list and try
 523       // again to allocate from it.
 524       append_secondary_free_list();
 525 
 526       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 527              "empty we should have moved at least one entry to the free_list");
 528       HeapRegion* res = _hrm.allocate_free_region(is_old);
 529       if (G1ConcRegionFreeingVerbose) {
 530         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 531                                "allocated "HR_FORMAT" from secondary_free_list",
 532                                HR_FORMAT_PARAMS(res));
 533       }
 534       return res;
 535     }
 536 
 537     // Wait here until we get notified either when (a) there are no
 538     // more free regions coming or (b) some regions have been moved on
 539     // the secondary_free_list.
 540     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 541   }
 542 
 543   if (G1ConcRegionFreeingVerbose) {
 544     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 545                            "could not allocate from secondary_free_list");
 546   }
 547   return NULL;
 548 }
 549 
 550 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 551   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 552          "the only time we use this to allocate a humongous region is "
 553          "when we are allocating a single humongous region");
 554 
 555   HeapRegion* res;
 556   if (G1StressConcRegionFreeing) {
 557     if (!_secondary_free_list.is_empty()) {
 558       if (G1ConcRegionFreeingVerbose) {
 559         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 560                                "forced to look at the secondary_free_list");
 561       }
 562       res = new_region_try_secondary_free_list(is_old);
 563       if (res != NULL) {
 564         return res;
 565       }
 566     }
 567   }
 568 
 569   res = _hrm.allocate_free_region(is_old);
 570 
 571   if (res == NULL) {
 572     if (G1ConcRegionFreeingVerbose) {
 573       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 574                              "res == NULL, trying the secondary_free_list");
 575     }
 576     res = new_region_try_secondary_free_list(is_old);
 577   }
 578   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 579     // Currently, only attempts to allocate GC alloc regions set
 580     // do_expand to true. So, we should only reach here during a
 581     // safepoint. If this assumption changes we might have to
 582     // reconsider the use of _expand_heap_after_alloc_failure.
 583     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 584 
 585     ergo_verbose1(ErgoHeapSizing,
 586                   "attempt heap expansion",
 587                   ergo_format_reason("region allocation request failed")
 588                   ergo_format_byte("allocation request"),
 589                   word_size * HeapWordSize);
 590     if (expand(word_size * HeapWordSize)) {
 591       // Given that expand() succeeded in expanding the heap, and we
 592       // always expand the heap by an amount aligned to the heap
 593       // region size, the free list should in theory not be empty.
 594       // In either case allocate_free_region() will check for NULL.
 595       res = _hrm.allocate_free_region(is_old);
 596     } else {
 597       _expand_heap_after_alloc_failure = false;
 598     }
 599   }
 600   return res;
 601 }
 602 
 603 HeapWord*
 604 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 605                                                            uint num_regions,
 606                                                            size_t word_size,
 607                                                            AllocationContext_t context) {
 608   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 609   assert(isHumongous(word_size), "word_size should be humongous");
 610   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 611 
 612   // Index of last region in the series + 1.
 613   uint last = first + num_regions;
 614 
 615   // We need to initialize the region(s) we just discovered. This is
 616   // a bit tricky given that it can happen concurrently with
 617   // refinement threads refining cards on these regions and
 618   // potentially wanting to refine the BOT as they are scanning
 619   // those cards (this can happen shortly after a cleanup; see CR
 620   // 6991377). So we have to set up the region(s) carefully and in
 621   // a specific order.
 622 
 623   // The word size sum of all the regions we will allocate.
 624   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 625   assert(word_size <= word_size_sum, "sanity");
 626 
 627   // This will be the "starts humongous" region.
 628   HeapRegion* first_hr = region_at(first);
 629   // The header of the new object will be placed at the bottom of
 630   // the first region.
 631   HeapWord* new_obj = first_hr->bottom();
 632   // This will be the new end of the first region in the series that
 633   // should also match the end of the last region in the series.
 634   HeapWord* new_end = new_obj + word_size_sum;
 635   // This will be the new top of the first region that will reflect
 636   // this allocation.
 637   HeapWord* new_top = new_obj + word_size;
 638 
 639   // First, we need to zero the header of the space that we will be
 640   // allocating. When we update top further down, some refinement
 641   // threads might try to scan the region. By zeroing the header we
 642   // ensure that any thread that will try to scan the region will
 643   // come across the zero klass word and bail out.
 644   //
 645   // NOTE: It would not have been correct to have used
 646   // CollectedHeap::fill_with_object() and make the space look like
 647   // an int array. The thread that is doing the allocation will
 648   // later update the object header to a potentially different array
 649   // type and, for a very short period of time, the klass and length
 650   // fields will be inconsistent. This could cause a refinement
 651   // thread to calculate the object size incorrectly.
 652   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 653 
 654   // We will set up the first region as "starts humongous". This
 655   // will also update the BOT covering all the regions to reflect
 656   // that there is a single object that starts at the bottom of the
 657   // first region.
 658   first_hr->set_startsHumongous(new_top, new_end);
 659   first_hr->set_allocation_context(context);
 660   // Then, if there are any, we will set up the "continues
 661   // humongous" regions.
 662   HeapRegion* hr = NULL;
 663   for (uint i = first + 1; i < last; ++i) {
 664     hr = region_at(i);
 665     hr->set_continuesHumongous(first_hr);
 666     hr->set_allocation_context(context);
 667   }
 668   // If we have "continues humongous" regions (hr != NULL), then the
 669   // end of the last one should match new_end.
 670   assert(hr == NULL || hr->end() == new_end, "sanity");
 671 
 672   // Up to this point no concurrent thread would have been able to
 673   // do any scanning on any region in this series. All the top
 674   // fields still point to bottom, so the intersection between
 675   // [bottom,top] and [card_start,card_end] will be empty. Before we
 676   // update the top fields, we'll do a storestore to make sure that
 677   // no thread sees the update to top before the zeroing of the
 678   // object header and the BOT initialization.
 679   OrderAccess::storestore();
 680 
 681   // Now that the BOT and the object header have been initialized,
 682   // we can update top of the "starts humongous" region.
 683   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 684          "new_top should be in this region");
 685   first_hr->set_top(new_top);
 686   if (_hr_printer.is_active()) {
 687     HeapWord* bottom = first_hr->bottom();
 688     HeapWord* end = first_hr->orig_end();
 689     if ((first + 1) == last) {
 690       // the series has a single humongous region
 691       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 692     } else {
 693       // the series has more than one humongous regions
 694       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 695     }
 696   }
 697 
 698   // Now, we will update the top fields of the "continues humongous"
 699   // regions. The reason we need to do this is that, otherwise,
 700   // these regions would look empty and this will confuse parts of
 701   // G1. For example, the code that looks for a consecutive number
 702   // of empty regions will consider them empty and try to
 703   // re-allocate them. We can extend is_empty() to also include
 704   // !continuesHumongous(), but it is easier to just update the top
 705   // fields here. The way we set top for all regions (i.e., top ==
 706   // end for all regions but the last one, top == new_top for the
 707   // last one) is actually used when we will free up the humongous
 708   // region in free_humongous_region().
 709   hr = NULL;
 710   for (uint i = first + 1; i < last; ++i) {
 711     hr = region_at(i);
 712     if ((i + 1) == last) {
 713       // last continues humongous region
 714       assert(hr->bottom() < new_top && new_top <= hr->end(),
 715              "new_top should fall on this region");
 716       hr->set_top(new_top);
 717       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 718     } else {
 719       // not last one
 720       assert(new_top > hr->end(), "new_top should be above this region");
 721       hr->set_top(hr->end());
 722       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 723     }
 724   }
 725   // If we have continues humongous regions (hr != NULL), then the
 726   // end of the last one should match new_end and its top should
 727   // match new_top.
 728   assert(hr == NULL ||
 729          (hr->end() == new_end && hr->top() == new_top), "sanity");
 730   check_bitmaps("Humongous Region Allocation", first_hr);
 731 
 732   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 733   _allocator->increase_used(first_hr->used());
 734   _humongous_set.add(first_hr);
 735 
 736   return new_obj;
 737 }
 738 
 739 // If could fit into free regions w/o expansion, try.
 740 // Otherwise, if can expand, do so.
 741 // Otherwise, if using ex regions might help, try with ex given back.
 742 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 743   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 744 
 745   verify_region_sets_optional();
 746 
 747   uint first = G1_NO_HRM_INDEX;
 748   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 749 
 750   if (obj_regions == 1) {
 751     // Only one region to allocate, try to use a fast path by directly allocating
 752     // from the free lists. Do not try to expand here, we will potentially do that
 753     // later.
 754     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 755     if (hr != NULL) {
 756       first = hr->hrm_index();
 757     }
 758   } else {
 759     // We can't allocate humongous regions spanning more than one region while
 760     // cleanupComplete() is running, since some of the regions we find to be
 761     // empty might not yet be added to the free list. It is not straightforward
 762     // to know in which list they are on so that we can remove them. We only
 763     // need to do this if we need to allocate more than one region to satisfy the
 764     // current humongous allocation request. If we are only allocating one region
 765     // we use the one-region region allocation code (see above), that already
 766     // potentially waits for regions from the secondary free list.
 767     wait_while_free_regions_coming();
 768     append_secondary_free_list_if_not_empty_with_lock();
 769 
 770     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 771     // are lucky enough to find some.
 772     first = _hrm.find_contiguous_only_empty(obj_regions);
 773     if (first != G1_NO_HRM_INDEX) {
 774       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 775     }
 776   }
 777 
 778   if (first == G1_NO_HRM_INDEX) {
 779     // Policy: We could not find enough regions for the humongous object in the
 780     // free list. Look through the heap to find a mix of free and uncommitted regions.
 781     // If so, try expansion.
 782     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 783     if (first != G1_NO_HRM_INDEX) {
 784       // We found something. Make sure these regions are committed, i.e. expand
 785       // the heap. Alternatively we could do a defragmentation GC.
 786       ergo_verbose1(ErgoHeapSizing,
 787                     "attempt heap expansion",
 788                     ergo_format_reason("humongous allocation request failed")
 789                     ergo_format_byte("allocation request"),
 790                     word_size * HeapWordSize);
 791 
 792       _hrm.expand_at(first, obj_regions);
 793       g1_policy()->record_new_heap_size(num_regions());
 794 
 795 #ifdef ASSERT
 796       for (uint i = first; i < first + obj_regions; ++i) {
 797         HeapRegion* hr = region_at(i);
 798         assert(hr->is_free(), "sanity");
 799         assert(hr->is_empty(), "sanity");
 800         assert(is_on_master_free_list(hr), "sanity");
 801       }
 802 #endif
 803       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 804     } else {
 805       // Policy: Potentially trigger a defragmentation GC.
 806     }
 807   }
 808 
 809   HeapWord* result = NULL;
 810   if (first != G1_NO_HRM_INDEX) {
 811     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 812                                                        word_size, context);
 813     assert(result != NULL, "it should always return a valid result");
 814 
 815     // A successful humongous object allocation changes the used space
 816     // information of the old generation so we need to recalculate the
 817     // sizes and update the jstat counters here.
 818     g1mm()->update_sizes();
 819   }
 820 
 821   verify_region_sets_optional();
 822 
 823   return result;
 824 }
 825 
 826 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 827   assert_heap_not_locked_and_not_at_safepoint();
 828   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 829 
 830   uint dummy_gc_count_before;
 831   uint dummy_gclocker_retry_count = 0;
 832   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 833 }
 834 
 835 HeapWord*
 836 G1CollectedHeap::mem_allocate(size_t word_size,
 837                               bool*  gc_overhead_limit_was_exceeded) {
 838   assert_heap_not_locked_and_not_at_safepoint();
 839 
 840   // Loop until the allocation is satisfied, or unsatisfied after GC.
 841   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 842     uint gc_count_before;
 843 
 844     HeapWord* result = NULL;
 845     if (!isHumongous(word_size)) {
 846       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 847     } else {
 848       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 849     }
 850     if (result != NULL) {
 851       return result;
 852     }
 853 
 854     // Create the garbage collection operation...
 855     VM_G1CollectForAllocation op(gc_count_before, word_size);
 856     op.set_allocation_context(AllocationContext::current());
 857 
 858     // ...and get the VM thread to execute it.
 859     VMThread::execute(&op);
 860 
 861     if (op.prologue_succeeded() && op.pause_succeeded()) {
 862       // If the operation was successful we'll return the result even
 863       // if it is NULL. If the allocation attempt failed immediately
 864       // after a Full GC, it's unlikely we'll be able to allocate now.
 865       HeapWord* result = op.result();
 866       if (result != NULL && !isHumongous(word_size)) {
 867         // Allocations that take place on VM operations do not do any
 868         // card dirtying and we have to do it here. We only have to do
 869         // this for non-humongous allocations, though.
 870         dirty_young_block(result, word_size);
 871       }
 872       return result;
 873     } else {
 874       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 875         return NULL;
 876       }
 877       assert(op.result() == NULL,
 878              "the result should be NULL if the VM op did not succeed");
 879     }
 880 
 881     // Give a warning if we seem to be looping forever.
 882     if ((QueuedAllocationWarningCount > 0) &&
 883         (try_count % QueuedAllocationWarningCount == 0)) {
 884       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 885     }
 886   }
 887 
 888   ShouldNotReachHere();
 889   return NULL;
 890 }
 891 
 892 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 893                                                    AllocationContext_t context,
 894                                                    uint* gc_count_before_ret,
 895                                                    uint* gclocker_retry_count_ret) {
 896   // Make sure you read the note in attempt_allocation_humongous().
 897 
 898   assert_heap_not_locked_and_not_at_safepoint();
 899   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 900          "be called for humongous allocation requests");
 901 
 902   // We should only get here after the first-level allocation attempt
 903   // (attempt_allocation()) failed to allocate.
 904 
 905   // We will loop until a) we manage to successfully perform the
 906   // allocation or b) we successfully schedule a collection which
 907   // fails to perform the allocation. b) is the only case when we'll
 908   // return NULL.
 909   HeapWord* result = NULL;
 910   for (int try_count = 1; /* we'll return */; try_count += 1) {
 911     bool should_try_gc;
 912     uint gc_count_before;
 913 
 914     {
 915       MutexLockerEx x(Heap_lock);
 916       result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
 917                                                                                     false /* bot_updates */);
 918       if (result != NULL) {
 919         return result;
 920       }
 921 
 922       // If we reach here, attempt_allocation_locked() above failed to
 923       // allocate a new region. So the mutator alloc region should be NULL.
 924       assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
 925 
 926       if (GC_locker::is_active_and_needs_gc()) {
 927         if (g1_policy()->can_expand_young_list()) {
 928           // No need for an ergo verbose message here,
 929           // can_expand_young_list() does this when it returns true.
 930           result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
 931                                                                                        false /* bot_updates */);
 932           if (result != NULL) {
 933             return result;
 934           }
 935         }
 936         should_try_gc = false;
 937       } else {
 938         // The GCLocker may not be active but the GCLocker initiated
 939         // GC may not yet have been performed (GCLocker::needs_gc()
 940         // returns true). In this case we do not try this GC and
 941         // wait until the GCLocker initiated GC is performed, and
 942         // then retry the allocation.
 943         if (GC_locker::needs_gc()) {
 944           should_try_gc = false;
 945         } else {
 946           // Read the GC count while still holding the Heap_lock.
 947           gc_count_before = total_collections();
 948           should_try_gc = true;
 949         }
 950       }
 951     }
 952 
 953     if (should_try_gc) {
 954       bool succeeded;
 955       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 956                                    GCCause::_g1_inc_collection_pause);
 957       if (result != NULL) {
 958         assert(succeeded, "only way to get back a non-NULL result");
 959         return result;
 960       }
 961 
 962       if (succeeded) {
 963         // If we get here we successfully scheduled a collection which
 964         // failed to allocate. No point in trying to allocate
 965         // further. We'll just return NULL.
 966         MutexLockerEx x(Heap_lock);
 967         *gc_count_before_ret = total_collections();
 968         return NULL;
 969       }
 970     } else {
 971       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 972         MutexLockerEx x(Heap_lock);
 973         *gc_count_before_ret = total_collections();
 974         return NULL;
 975       }
 976       // The GCLocker is either active or the GCLocker initiated
 977       // GC has not yet been performed. Stall until it is and
 978       // then retry the allocation.
 979       GC_locker::stall_until_clear();
 980       (*gclocker_retry_count_ret) += 1;
 981     }
 982 
 983     // We can reach here if we were unsuccessful in scheduling a
 984     // collection (because another thread beat us to it) or if we were
 985     // stalled due to the GC locker. In either can we should retry the
 986     // allocation attempt in case another thread successfully
 987     // performed a collection and reclaimed enough space. We do the
 988     // first attempt (without holding the Heap_lock) here and the
 989     // follow-on attempt will be at the start of the next loop
 990     // iteration (after taking the Heap_lock).
 991     result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
 992                                                                            false /* bot_updates */);
 993     if (result != NULL) {
 994       return result;
 995     }
 996 
 997     // Give a warning if we seem to be looping forever.
 998     if ((QueuedAllocationWarningCount > 0) &&
 999         (try_count % QueuedAllocationWarningCount == 0)) {
1000       warning("G1CollectedHeap::attempt_allocation_slow() "
1001               "retries %d times", try_count);
1002     }
1003   }
1004 
1005   ShouldNotReachHere();
1006   return NULL;
1007 }
1008 
1009 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1010                                                         uint* gc_count_before_ret,
1011                                                         uint* gclocker_retry_count_ret) {
1012   // The structure of this method has a lot of similarities to
1013   // attempt_allocation_slow(). The reason these two were not merged
1014   // into a single one is that such a method would require several "if
1015   // allocation is not humongous do this, otherwise do that"
1016   // conditional paths which would obscure its flow. In fact, an early
1017   // version of this code did use a unified method which was harder to
1018   // follow and, as a result, it had subtle bugs that were hard to
1019   // track down. So keeping these two methods separate allows each to
1020   // be more readable. It will be good to keep these two in sync as
1021   // much as possible.
1022 
1023   assert_heap_not_locked_and_not_at_safepoint();
1024   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1025          "should only be called for humongous allocations");
1026 
1027   // Humongous objects can exhaust the heap quickly, so we should check if we
1028   // need to start a marking cycle at each humongous object allocation. We do
1029   // the check before we do the actual allocation. The reason for doing it
1030   // before the allocation is that we avoid having to keep track of the newly
1031   // allocated memory while we do a GC.
1032   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1033                                            word_size)) {
1034     collect(GCCause::_g1_humongous_allocation);
1035   }
1036 
1037   // We will loop until a) we manage to successfully perform the
1038   // allocation or b) we successfully schedule a collection which
1039   // fails to perform the allocation. b) is the only case when we'll
1040   // return NULL.
1041   HeapWord* result = NULL;
1042   for (int try_count = 1; /* we'll return */; try_count += 1) {
1043     bool should_try_gc;
1044     uint gc_count_before;
1045 
1046     {
1047       MutexLockerEx x(Heap_lock);
1048 
1049       // Given that humongous objects are not allocated in young
1050       // regions, we'll first try to do the allocation without doing a
1051       // collection hoping that there's enough space in the heap.
1052       result = humongous_obj_allocate(word_size, AllocationContext::current());
1053       if (result != NULL) {
1054         return result;
1055       }
1056 
1057       if (GC_locker::is_active_and_needs_gc()) {
1058         should_try_gc = false;
1059       } else {
1060          // The GCLocker may not be active but the GCLocker initiated
1061         // GC may not yet have been performed (GCLocker::needs_gc()
1062         // returns true). In this case we do not try this GC and
1063         // wait until the GCLocker initiated GC is performed, and
1064         // then retry the allocation.
1065         if (GC_locker::needs_gc()) {
1066           should_try_gc = false;
1067         } else {
1068           // Read the GC count while still holding the Heap_lock.
1069           gc_count_before = total_collections();
1070           should_try_gc = true;
1071         }
1072       }
1073     }
1074 
1075     if (should_try_gc) {
1076       // If we failed to allocate the humongous object, we should try to
1077       // do a collection pause (if we're allowed) in case it reclaims
1078       // enough space for the allocation to succeed after the pause.
1079 
1080       bool succeeded;
1081       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1082                                    GCCause::_g1_humongous_allocation);
1083       if (result != NULL) {
1084         assert(succeeded, "only way to get back a non-NULL result");
1085         return result;
1086       }
1087 
1088       if (succeeded) {
1089         // If we get here we successfully scheduled a collection which
1090         // failed to allocate. No point in trying to allocate
1091         // further. We'll just return NULL.
1092         MutexLockerEx x(Heap_lock);
1093         *gc_count_before_ret = total_collections();
1094         return NULL;
1095       }
1096     } else {
1097       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1098         MutexLockerEx x(Heap_lock);
1099         *gc_count_before_ret = total_collections();
1100         return NULL;
1101       }
1102       // The GCLocker is either active or the GCLocker initiated
1103       // GC has not yet been performed. Stall until it is and
1104       // then retry the allocation.
1105       GC_locker::stall_until_clear();
1106       (*gclocker_retry_count_ret) += 1;
1107     }
1108 
1109     // We can reach here if we were unsuccessful in scheduling a
1110     // collection (because another thread beat us to it) or if we were
1111     // stalled due to the GC locker. In either can we should retry the
1112     // allocation attempt in case another thread successfully
1113     // performed a collection and reclaimed enough space.  Give a
1114     // warning if we seem to be looping forever.
1115 
1116     if ((QueuedAllocationWarningCount > 0) &&
1117         (try_count % QueuedAllocationWarningCount == 0)) {
1118       warning("G1CollectedHeap::attempt_allocation_humongous() "
1119               "retries %d times", try_count);
1120     }
1121   }
1122 
1123   ShouldNotReachHere();
1124   return NULL;
1125 }
1126 
1127 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1128                                                            AllocationContext_t context,
1129                                                            bool expect_null_mutator_alloc_region) {
1130   assert_at_safepoint(true /* should_be_vm_thread */);
1131   assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1132                                              !expect_null_mutator_alloc_region,
1133          "the current alloc region was unexpectedly found to be non-NULL");
1134 
1135   if (!isHumongous(word_size)) {
1136     return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1137                                                       false /* bot_updates */);
1138   } else {
1139     HeapWord* result = humongous_obj_allocate(word_size, context);
1140     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1141       g1_policy()->set_initiate_conc_mark_if_possible();
1142     }
1143     return result;
1144   }
1145 
1146   ShouldNotReachHere();
1147 }
1148 
1149 class PostMCRemSetClearClosure: public HeapRegionClosure {
1150   G1CollectedHeap* _g1h;
1151   ModRefBarrierSet* _mr_bs;
1152 public:
1153   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1154     _g1h(g1h), _mr_bs(mr_bs) {}
1155 
1156   bool doHeapRegion(HeapRegion* r) {
1157     HeapRegionRemSet* hrrs = r->rem_set();
1158 
1159     if (r->continuesHumongous()) {
1160       // We'll assert that the strong code root list and RSet is empty
1161       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1162       assert(hrrs->occupied() == 0, "RSet should be empty");
1163       return false;
1164     }
1165 
1166     _g1h->reset_gc_time_stamps(r);
1167     hrrs->clear();
1168     // You might think here that we could clear just the cards
1169     // corresponding to the used region.  But no: if we leave a dirty card
1170     // in a region we might allocate into, then it would prevent that card
1171     // from being enqueued, and cause it to be missed.
1172     // Re: the performance cost: we shouldn't be doing full GC anyway!
1173     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1174 
1175     return false;
1176   }
1177 };
1178 
1179 void G1CollectedHeap::clear_rsets_post_compaction() {
1180   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1181   heap_region_iterate(&rs_clear);
1182 }
1183 
1184 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1185   G1CollectedHeap*   _g1h;
1186   UpdateRSOopClosure _cl;
1187   int                _worker_i;
1188 public:
1189   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1190     _cl(g1->g1_rem_set(), worker_i),
1191     _worker_i(worker_i),
1192     _g1h(g1)
1193   { }
1194 
1195   bool doHeapRegion(HeapRegion* r) {
1196     if (!r->continuesHumongous()) {
1197       _cl.set_from(r);
1198       r->oop_iterate(&_cl);
1199     }
1200     return false;
1201   }
1202 };
1203 
1204 class ParRebuildRSTask: public AbstractGangTask {
1205   G1CollectedHeap* _g1;
1206 public:
1207   ParRebuildRSTask(G1CollectedHeap* g1)
1208     : AbstractGangTask("ParRebuildRSTask"),
1209       _g1(g1)
1210   { }
1211 
1212   void work(uint worker_id) {
1213     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1214     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1215                                           _g1->workers()->active_workers(),
1216                                          HeapRegion::RebuildRSClaimValue);
1217   }
1218 };
1219 
1220 class PostCompactionPrinterClosure: public HeapRegionClosure {
1221 private:
1222   G1HRPrinter* _hr_printer;
1223 public:
1224   bool doHeapRegion(HeapRegion* hr) {
1225     assert(!hr->is_young(), "not expecting to find young regions");
1226     if (hr->is_free()) {
1227       // We only generate output for non-empty regions.
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 if (hr->continuesHumongous()) {
1236       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1237     } else if (hr->is_old()) {
1238       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1239     } else {
1240       ShouldNotReachHere();
1241     }
1242     return false;
1243   }
1244 
1245   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1246     : _hr_printer(hr_printer) { }
1247 };
1248 
1249 void G1CollectedHeap::print_hrm_post_compaction() {
1250   PostCompactionPrinterClosure cl(hr_printer());
1251   heap_region_iterate(&cl);
1252 }
1253 
1254 bool G1CollectedHeap::do_collection(bool explicit_gc,
1255                                     bool clear_all_soft_refs,
1256                                     size_t word_size) {
1257   assert_at_safepoint(true /* should_be_vm_thread */);
1258 
1259   if (GC_locker::check_active_before_gc()) {
1260     return false;
1261   }
1262 
1263   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1264   gc_timer->register_gc_start();
1265 
1266   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1267   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1268 
1269   SvcGCMarker sgcm(SvcGCMarker::FULL);
1270   ResourceMark rm;
1271 
1272   print_heap_before_gc();
1273   trace_heap_before_gc(gc_tracer);
1274 
1275   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1276 
1277   verify_region_sets_optional();
1278 
1279   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1280                            collector_policy()->should_clear_all_soft_refs();
1281 
1282   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1283 
1284   {
1285     IsGCActiveMark x;
1286 
1287     // Timing
1288     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1289     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1290 
1291     {
1292       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1293       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1294       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1295 
1296       double start = os::elapsedTime();
1297       g1_policy()->record_full_collection_start();
1298 
1299       // Note: When we have a more flexible GC logging framework that
1300       // allows us to add optional attributes to a GC log record we
1301       // could consider timing and reporting how long we wait in the
1302       // following two methods.
1303       wait_while_free_regions_coming();
1304       // If we start the compaction before the CM threads finish
1305       // scanning the root regions we might trip them over as we'll
1306       // be moving objects / updating references. So let's wait until
1307       // they are done. By telling them to abort, they should complete
1308       // early.
1309       _cm->root_regions()->abort();
1310       _cm->root_regions()->wait_until_scan_finished();
1311       append_secondary_free_list_if_not_empty_with_lock();
1312 
1313       gc_prologue(true);
1314       increment_total_collections(true /* full gc */);
1315       increment_old_marking_cycles_started();
1316 
1317       assert(used() == recalculate_used(), "Should be equal");
1318 
1319       verify_before_gc();
1320 
1321       check_bitmaps("Full GC Start");
1322       pre_full_gc_dump(gc_timer);
1323 
1324       COMPILER2_PRESENT(DerivedPointerTable::clear());
1325 
1326       // Disable discovery and empty the discovered lists
1327       // for the CM ref processor.
1328       ref_processor_cm()->disable_discovery();
1329       ref_processor_cm()->abandon_partial_discovery();
1330       ref_processor_cm()->verify_no_references_recorded();
1331 
1332       // Abandon current iterations of concurrent marking and concurrent
1333       // refinement, if any are in progress. We have to do this before
1334       // wait_until_scan_finished() below.
1335       concurrent_mark()->abort();
1336 
1337       // Make sure we'll choose a new allocation region afterwards.
1338       _allocator->release_mutator_alloc_region();
1339       _allocator->abandon_gc_alloc_regions();
1340       g1_rem_set()->cleanupHRRS();
1341 
1342       // We should call this after we retire any currently active alloc
1343       // regions so that all the ALLOC / RETIRE events are generated
1344       // before the start GC event.
1345       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1346 
1347       // We may have added regions to the current incremental collection
1348       // set between the last GC or pause and now. We need to clear the
1349       // incremental collection set and then start rebuilding it afresh
1350       // after this full GC.
1351       abandon_collection_set(g1_policy()->inc_cset_head());
1352       g1_policy()->clear_incremental_cset();
1353       g1_policy()->stop_incremental_cset_building();
1354 
1355       tear_down_region_sets(false /* free_list_only */);
1356       g1_policy()->set_gcs_are_young(true);
1357 
1358       // See the comments in g1CollectedHeap.hpp and
1359       // G1CollectedHeap::ref_processing_init() about
1360       // how reference processing currently works in G1.
1361 
1362       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1363       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1364 
1365       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1366       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1367 
1368       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1369       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1370 
1371       // Do collection work
1372       {
1373         HandleMark hm;  // Discard invalid handles created during gc
1374         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1375       }
1376 
1377       assert(num_free_regions() == 0, "we should not have added any free regions");
1378       rebuild_region_sets(false /* free_list_only */);
1379 
1380       // Enqueue any discovered reference objects that have
1381       // not been removed from the discovered lists.
1382       ref_processor_stw()->enqueue_discovered_references();
1383 
1384       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1385 
1386       MemoryService::track_memory_usage();
1387 
1388       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1389       ref_processor_stw()->verify_no_references_recorded();
1390 
1391       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1392       ClassLoaderDataGraph::purge();
1393       MetaspaceAux::verify_metrics();
1394 
1395       // Note: since we've just done a full GC, concurrent
1396       // marking is no longer active. Therefore we need not
1397       // re-enable reference discovery for the CM ref processor.
1398       // That will be done at the start of the next marking cycle.
1399       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1400       ref_processor_cm()->verify_no_references_recorded();
1401 
1402       reset_gc_time_stamp();
1403       // Since everything potentially moved, we will clear all remembered
1404       // sets, and clear all cards.  Later we will rebuild remembered
1405       // sets. We will also reset the GC time stamps of the regions.
1406       clear_rsets_post_compaction();
1407       check_gc_time_stamps();
1408 
1409       // Resize the heap if necessary.
1410       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1411 
1412       if (_hr_printer.is_active()) {
1413         // We should do this after we potentially resize the heap so
1414         // that all the COMMIT / UNCOMMIT events are generated before
1415         // the end GC event.
1416 
1417         print_hrm_post_compaction();
1418         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1419       }
1420 
1421       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1422       if (hot_card_cache->use_cache()) {
1423         hot_card_cache->reset_card_counts();
1424         hot_card_cache->reset_hot_cache();
1425       }
1426 
1427       // Rebuild remembered sets of all regions.
1428       if (G1CollectedHeap::use_parallel_gc_threads()) {
1429         uint n_workers =
1430           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1431                                                   workers()->active_workers(),
1432                                                   Threads::number_of_non_daemon_threads());
1433         assert(UseDynamicNumberOfGCThreads ||
1434                n_workers == workers()->total_workers(),
1435                "If not dynamic should be using all the  workers");
1436         workers()->set_active_workers(n_workers);
1437         // Set parallel threads in the heap (_n_par_threads) only
1438         // before a parallel phase and always reset it to 0 after
1439         // the phase so that the number of parallel threads does
1440         // no get carried forward to a serial phase where there
1441         // may be code that is "possibly_parallel".
1442         set_par_threads(n_workers);
1443 
1444         ParRebuildRSTask rebuild_rs_task(this);
1445         assert(check_heap_region_claim_values(
1446                HeapRegion::InitialClaimValue), "sanity check");
1447         assert(UseDynamicNumberOfGCThreads ||
1448                workers()->active_workers() == workers()->total_workers(),
1449                "Unless dynamic should use total workers");
1450         // Use the most recent number of  active workers
1451         assert(workers()->active_workers() > 0,
1452                "Active workers not properly set");
1453         set_par_threads(workers()->active_workers());
1454         workers()->run_task(&rebuild_rs_task);
1455         set_par_threads(0);
1456         assert(check_heap_region_claim_values(
1457                HeapRegion::RebuildRSClaimValue), "sanity check");
1458         reset_heap_region_claim_values();
1459       } else {
1460         RebuildRSOutOfRegionClosure rebuild_rs(this);
1461         heap_region_iterate(&rebuild_rs);
1462       }
1463 
1464       // Rebuild the strong code root lists for each region
1465       rebuild_strong_code_roots();
1466 
1467       if (true) { // FIXME
1468         MetaspaceGC::compute_new_size();
1469       }
1470 
1471 #ifdef TRACESPINNING
1472       ParallelTaskTerminator::print_termination_counts();
1473 #endif
1474 
1475       // Discard all rset updates
1476       JavaThread::dirty_card_queue_set().abandon_logs();
1477       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1478 
1479       _young_list->reset_sampled_info();
1480       // At this point there should be no regions in the
1481       // entire heap tagged as young.
1482       assert(check_young_list_empty(true /* check_heap */),
1483              "young list should be empty at this point");
1484 
1485       // Update the number of full collections that have been completed.
1486       increment_old_marking_cycles_completed(false /* concurrent */);
1487 
1488       _hrm.verify_optional();
1489       verify_region_sets_optional();
1490 
1491       verify_after_gc();
1492 
1493       // Clear the previous marking bitmap, if needed for bitmap verification.
1494       // Note we cannot do this when we clear the next marking bitmap in
1495       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1496       // objects marked during a full GC against the previous bitmap.
1497       // But we need to clear it before calling check_bitmaps below since
1498       // the full GC has compacted objects and updated TAMS but not updated
1499       // the prev bitmap.
1500       if (G1VerifyBitmaps) {
1501         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1502       }
1503       check_bitmaps("Full GC End");
1504 
1505       // Start a new incremental collection set for the next pause
1506       assert(g1_policy()->collection_set() == NULL, "must be");
1507       g1_policy()->start_incremental_cset_building();
1508 
1509       clear_cset_fast_test();
1510 
1511       _allocator->init_mutator_alloc_region();
1512 
1513       double end = os::elapsedTime();
1514       g1_policy()->record_full_collection_end();
1515 
1516       if (G1Log::fine()) {
1517         g1_policy()->print_heap_transition();
1518       }
1519 
1520       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1521       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1522       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1523       // before any GC notifications are raised.
1524       g1mm()->update_sizes();
1525 
1526       gc_epilogue(true);
1527     }
1528 
1529     if (G1Log::finer()) {
1530       g1_policy()->print_detailed_heap_transition(true /* full */);
1531     }
1532 
1533     print_heap_after_gc();
1534     trace_heap_after_gc(gc_tracer);
1535 
1536     post_full_gc_dump(gc_timer);
1537 
1538     gc_timer->register_gc_end();
1539     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1540   }
1541 
1542   return true;
1543 }
1544 
1545 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1546   // do_collection() will return whether it succeeded in performing
1547   // the GC. Currently, there is no facility on the
1548   // do_full_collection() API to notify the caller than the collection
1549   // did not succeed (e.g., because it was locked out by the GC
1550   // locker). So, right now, we'll ignore the return value.
1551   bool dummy = do_collection(true,                /* explicit_gc */
1552                              clear_all_soft_refs,
1553                              0                    /* word_size */);
1554 }
1555 
1556 // This code is mostly copied from TenuredGeneration.
1557 void
1558 G1CollectedHeap::
1559 resize_if_necessary_after_full_collection(size_t word_size) {
1560   // Include the current allocation, if any, and bytes that will be
1561   // pre-allocated to support collections, as "used".
1562   const size_t used_after_gc = used();
1563   const size_t capacity_after_gc = capacity();
1564   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1565 
1566   // This is enforced in arguments.cpp.
1567   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1568          "otherwise the code below doesn't make sense");
1569 
1570   // We don't have floating point command-line arguments
1571   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1572   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1573   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1574   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1575 
1576   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1577   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1578 
1579   // We have to be careful here as these two calculations can overflow
1580   // 32-bit size_t's.
1581   double used_after_gc_d = (double) used_after_gc;
1582   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1583   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1584 
1585   // Let's make sure that they are both under the max heap size, which
1586   // by default will make them fit into a size_t.
1587   double desired_capacity_upper_bound = (double) max_heap_size;
1588   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1589                                     desired_capacity_upper_bound);
1590   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1591                                     desired_capacity_upper_bound);
1592 
1593   // We can now safely turn them into size_t's.
1594   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1595   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1596 
1597   // This assert only makes sense here, before we adjust them
1598   // with respect to the min and max heap size.
1599   assert(minimum_desired_capacity <= maximum_desired_capacity,
1600          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1601                  "maximum_desired_capacity = "SIZE_FORMAT,
1602                  minimum_desired_capacity, maximum_desired_capacity));
1603 
1604   // Should not be greater than the heap max size. No need to adjust
1605   // it with respect to the heap min size as it's a lower bound (i.e.,
1606   // we'll try to make the capacity larger than it, not smaller).
1607   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1608   // Should not be less than the heap min size. No need to adjust it
1609   // with respect to the heap max size as it's an upper bound (i.e.,
1610   // we'll try to make the capacity smaller than it, not greater).
1611   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1612 
1613   if (capacity_after_gc < minimum_desired_capacity) {
1614     // Don't expand unless it's significant
1615     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1616     ergo_verbose4(ErgoHeapSizing,
1617                   "attempt heap expansion",
1618                   ergo_format_reason("capacity lower than "
1619                                      "min desired capacity after Full GC")
1620                   ergo_format_byte("capacity")
1621                   ergo_format_byte("occupancy")
1622                   ergo_format_byte_perc("min desired capacity"),
1623                   capacity_after_gc, used_after_gc,
1624                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1625     expand(expand_bytes);
1626 
1627     // No expansion, now see if we want to shrink
1628   } else if (capacity_after_gc > maximum_desired_capacity) {
1629     // Capacity too large, compute shrinking size
1630     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1631     ergo_verbose4(ErgoHeapSizing,
1632                   "attempt heap shrinking",
1633                   ergo_format_reason("capacity higher than "
1634                                      "max desired capacity after Full GC")
1635                   ergo_format_byte("capacity")
1636                   ergo_format_byte("occupancy")
1637                   ergo_format_byte_perc("max desired capacity"),
1638                   capacity_after_gc, used_after_gc,
1639                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1640     shrink(shrink_bytes);
1641   }
1642 }
1643 
1644 
1645 HeapWord*
1646 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1647                                            AllocationContext_t context,
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                                     context,
1656                                     false /* expect_null_mutator_alloc_region */);
1657   if (result != NULL) {
1658     assert(*succeeded, "sanity");
1659     return result;
1660   }
1661 
1662   // In a G1 heap, we're supposed to keep allocation from failing by
1663   // incremental pauses.  Therefore, at least for now, we'll favor
1664   // expansion over collection.  (This might change in the future if we can
1665   // do something smarter than full collection to satisfy a failed alloc.)
1666   result = expand_and_allocate(word_size, context);
1667   if (result != NULL) {
1668     assert(*succeeded, "sanity");
1669     return result;
1670   }
1671 
1672   // Expansion didn't work, we'll try to do a Full GC.
1673   bool gc_succeeded = do_collection(false, /* explicit_gc */
1674                                     false, /* clear_all_soft_refs */
1675                                     word_size);
1676   if (!gc_succeeded) {
1677     *succeeded = false;
1678     return NULL;
1679   }
1680 
1681   // Retry the allocation
1682   result = attempt_allocation_at_safepoint(word_size,
1683                                            context,
1684                                            true /* expect_null_mutator_alloc_region */);
1685   if (result != NULL) {
1686     assert(*succeeded, "sanity");
1687     return result;
1688   }
1689 
1690   // Then, try a Full GC that will collect all soft references.
1691   gc_succeeded = do_collection(false, /* explicit_gc */
1692                                true,  /* clear_all_soft_refs */
1693                                word_size);
1694   if (!gc_succeeded) {
1695     *succeeded = false;
1696     return NULL;
1697   }
1698 
1699   // Retry the allocation once more
1700   result = attempt_allocation_at_safepoint(word_size,
1701                                            context,
1702                                            true /* expect_null_mutator_alloc_region */);
1703   if (result != NULL) {
1704     assert(*succeeded, "sanity");
1705     return result;
1706   }
1707 
1708   assert(!collector_policy()->should_clear_all_soft_refs(),
1709          "Flag should have been handled and cleared prior to this point");
1710 
1711   // What else?  We might try synchronous finalization later.  If the total
1712   // space available is large enough for the allocation, then a more
1713   // complete compaction phase than we've tried so far might be
1714   // appropriate.
1715   assert(*succeeded, "sanity");
1716   return NULL;
1717 }
1718 
1719 // Attempting to expand the heap sufficiently
1720 // to support an allocation of the given "word_size".  If
1721 // successful, perform the allocation and return the address of the
1722 // allocated block, or else "NULL".
1723 
1724 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1725   assert_at_safepoint(true /* should_be_vm_thread */);
1726 
1727   verify_region_sets_optional();
1728 
1729   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1730   ergo_verbose1(ErgoHeapSizing,
1731                 "attempt heap expansion",
1732                 ergo_format_reason("allocation request failed")
1733                 ergo_format_byte("allocation request"),
1734                 word_size * HeapWordSize);
1735   if (expand(expand_bytes)) {
1736     _hrm.verify_optional();
1737     verify_region_sets_optional();
1738     return attempt_allocation_at_safepoint(word_size,
1739                                            context,
1740                                            false /* expect_null_mutator_alloc_region */);
1741   }
1742   return NULL;
1743 }
1744 
1745 bool G1CollectedHeap::expand(size_t expand_bytes) {
1746   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1747   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1748                                        HeapRegion::GrainBytes);
1749   ergo_verbose2(ErgoHeapSizing,
1750                 "expand the heap",
1751                 ergo_format_byte("requested expansion amount")
1752                 ergo_format_byte("attempted expansion amount"),
1753                 expand_bytes, aligned_expand_bytes);
1754 
1755   if (is_maximal_no_gc()) {
1756     ergo_verbose0(ErgoHeapSizing,
1757                       "did not expand the heap",
1758                       ergo_format_reason("heap already fully expanded"));
1759     return false;
1760   }
1761 
1762   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1763   assert(regions_to_expand > 0, "Must expand by at least one region");
1764 
1765   uint expanded_by = _hrm.expand_by(regions_to_expand);
1766 
1767   if (expanded_by > 0) {
1768     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1769     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1770     g1_policy()->record_new_heap_size(num_regions());
1771   } else {
1772     ergo_verbose0(ErgoHeapSizing,
1773                   "did not expand the heap",
1774                   ergo_format_reason("heap expansion operation failed"));
1775     // The expansion of the virtual storage space was unsuccessful.
1776     // Let's see if it was because we ran out of swap.
1777     if (G1ExitOnExpansionFailure &&
1778         _hrm.available() >= regions_to_expand) {
1779       // We had head room...
1780       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1781     }
1782   }
1783   return regions_to_expand > 0;
1784 }
1785 
1786 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1787   size_t aligned_shrink_bytes =
1788     ReservedSpace::page_align_size_down(shrink_bytes);
1789   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1790                                          HeapRegion::GrainBytes);
1791   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1792 
1793   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1794   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1795 
1796   ergo_verbose3(ErgoHeapSizing,
1797                 "shrink the heap",
1798                 ergo_format_byte("requested shrinking amount")
1799                 ergo_format_byte("aligned shrinking amount")
1800                 ergo_format_byte("attempted shrinking amount"),
1801                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1802   if (num_regions_removed > 0) {
1803     g1_policy()->record_new_heap_size(num_regions());
1804   } else {
1805     ergo_verbose0(ErgoHeapSizing,
1806                   "did not shrink the heap",
1807                   ergo_format_reason("heap shrinking operation failed"));
1808   }
1809 }
1810 
1811 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1812   verify_region_sets_optional();
1813 
1814   // We should only reach here at the end of a Full GC which means we
1815   // should not not be holding to any GC alloc regions. The method
1816   // below will make sure of that and do any remaining clean up.
1817   _allocator->abandon_gc_alloc_regions();
1818 
1819   // Instead of tearing down / rebuilding the free lists here, we
1820   // could instead use the remove_all_pending() method on free_list to
1821   // remove only the ones that we need to remove.
1822   tear_down_region_sets(true /* free_list_only */);
1823   shrink_helper(shrink_bytes);
1824   rebuild_region_sets(true /* free_list_only */);
1825 
1826   _hrm.verify_optional();
1827   verify_region_sets_optional();
1828 }
1829 
1830 // Public methods.
1831 
1832 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1833 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1834 #endif // _MSC_VER
1835 
1836 
1837 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1838   SharedHeap(policy_),
1839   _g1_policy(policy_),
1840   _dirty_card_queue_set(false),
1841   _into_cset_dirty_card_queue_set(false),
1842   _is_alive_closure_cm(this),
1843   _is_alive_closure_stw(this),
1844   _ref_processor_cm(NULL),
1845   _ref_processor_stw(NULL),
1846   _bot_shared(NULL),
1847   _evac_failure_scan_stack(NULL),
1848   _mark_in_progress(false),
1849   _cg1r(NULL),
1850   _g1mm(NULL),
1851   _refine_cte_cl(NULL),
1852   _full_collection(false),
1853   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1854   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1855   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1856   _humongous_reclaim_candidates(),
1857   _has_humongous_reclaim_candidates(false),
1858   _free_regions_coming(false),
1859   _young_list(new YoungList(this)),
1860   _gc_time_stamp(0),
1861   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1862   _old_plab_stats(OldPLABSize, PLABWeight),
1863   _expand_heap_after_alloc_failure(true),
1864   _surviving_young_words(NULL),
1865   _old_marking_cycles_started(0),
1866   _old_marking_cycles_completed(0),
1867   _concurrent_cycle_started(false),
1868   _heap_summary_sent(false),
1869   _in_cset_fast_test(),
1870   _dirty_cards_region_list(NULL),
1871   _worker_cset_start_region(NULL),
1872   _worker_cset_start_region_time_stamp(NULL),
1873   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1874   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1875   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1876   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1877 
1878   _g1h = this;
1879 
1880   _allocator = G1Allocator::create_allocator(_g1h);
1881   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1882 
1883   int n_queues = MAX2((int)ParallelGCThreads, 1);
1884   _task_queues = new RefToScanQueueSet(n_queues);
1885 
1886   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1887   assert(n_rem_sets > 0, "Invariant.");
1888 
1889   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1890   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1891   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1892 
1893   for (int i = 0; i < n_queues; i++) {
1894     RefToScanQueue* q = new RefToScanQueue();
1895     q->initialize();
1896     _task_queues->register_queue(i, q);
1897     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1898   }
1899   clear_cset_start_regions();
1900 
1901   // Initialize the G1EvacuationFailureALot counters and flags.
1902   NOT_PRODUCT(reset_evacuation_should_fail();)
1903 
1904   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1905 }
1906 
1907 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1908                                                                  size_t size,
1909                                                                  size_t translation_factor) {
1910   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1911   // Allocate a new reserved space, preferring to use large pages.
1912   ReservedSpace rs(size, preferred_page_size);
1913   G1RegionToSpaceMapper* result  =
1914     G1RegionToSpaceMapper::create_mapper(rs,
1915                                          size,
1916                                          rs.alignment(),
1917                                          HeapRegion::GrainBytes,
1918                                          translation_factor,
1919                                          mtGC);
1920   if (TracePageSizes) {
1921     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1922                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1923   }
1924   return result;
1925 }
1926 
1927 jint G1CollectedHeap::initialize() {
1928   CollectedHeap::pre_initialize();
1929   os::enable_vtime();
1930 
1931   G1Log::init();
1932 
1933   // Necessary to satisfy locking discipline assertions.
1934 
1935   MutexLocker x(Heap_lock);
1936 
1937   // We have to initialize the printer before committing the heap, as
1938   // it will be used then.
1939   _hr_printer.set_active(G1PrintHeapRegions);
1940 
1941   // While there are no constraints in the GC code that HeapWordSize
1942   // be any particular value, there are multiple other areas in the
1943   // system which believe this to be true (e.g. oop->object_size in some
1944   // cases incorrectly returns the size in wordSize units rather than
1945   // HeapWordSize).
1946   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1947 
1948   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1949   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1950   size_t heap_alignment = collector_policy()->heap_alignment();
1951 
1952   // Ensure that the sizes are properly aligned.
1953   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1954   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1955   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1956 
1957   _refine_cte_cl = new RefineCardTableEntryClosure();
1958 
1959   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1960 
1961   // Reserve the maximum.
1962 
1963   // When compressed oops are enabled, the preferred heap base
1964   // is calculated by subtracting the requested size from the
1965   // 32Gb boundary and using the result as the base address for
1966   // heap reservation. If the requested size is not aligned to
1967   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1968   // into the ReservedHeapSpace constructor) then the actual
1969   // base of the reserved heap may end up differing from the
1970   // address that was requested (i.e. the preferred heap base).
1971   // If this happens then we could end up using a non-optimal
1972   // compressed oops mode.
1973 
1974   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1975                                                  heap_alignment);
1976 
1977   // It is important to do this in a way such that concurrent readers can't
1978   // temporarily think something is in the heap.  (I've actually seen this
1979   // happen in asserts: DLD.)
1980   _reserved.set_word_size(0);
1981   _reserved.set_start((HeapWord*)heap_rs.base());
1982   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1983 
1984   // Create the gen rem set (and barrier set) for the entire reserved region.
1985   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1986   set_barrier_set(rem_set()->bs());
1987   if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1988     vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1989     return JNI_ENOMEM;
1990   }
1991 
1992   // Also create a G1 rem set.
1993   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1994 
1995   // Carve out the G1 part of the heap.
1996 
1997   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1998   G1RegionToSpaceMapper* heap_storage =
1999     G1RegionToSpaceMapper::create_mapper(g1_rs,
2000                                          g1_rs.size(),
2001                                          UseLargePages ? os::large_page_size() : os::vm_page_size(),
2002                                          HeapRegion::GrainBytes,
2003                                          1,
2004                                          mtJavaHeap);
2005   heap_storage->set_mapping_changed_listener(&_listener);
2006 
2007   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2008   G1RegionToSpaceMapper* bot_storage =
2009     create_aux_memory_mapper("Block offset table",
2010                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2011                              G1BlockOffsetSharedArray::N_bytes);
2012 
2013   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2014   G1RegionToSpaceMapper* cardtable_storage =
2015     create_aux_memory_mapper("Card table",
2016                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2017                              G1BlockOffsetSharedArray::N_bytes);
2018 
2019   G1RegionToSpaceMapper* card_counts_storage =
2020     create_aux_memory_mapper("Card counts table",
2021                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2022                              G1BlockOffsetSharedArray::N_bytes);
2023 
2024   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2025   G1RegionToSpaceMapper* prev_bitmap_storage =
2026     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
2027   G1RegionToSpaceMapper* next_bitmap_storage =
2028     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
2029 
2030   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2031   g1_barrier_set()->initialize(cardtable_storage);
2032    // Do later initialization work for concurrent refinement.
2033   _cg1r->init(card_counts_storage);
2034 
2035   // 6843694 - ensure that the maximum region index can fit
2036   // in the remembered set structures.
2037   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2038   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2039 
2040   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2041   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2042   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2043             "too many cards per region");
2044 
2045   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2046 
2047   _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
2048 
2049   _g1h = this;
2050 
2051   {
2052     HeapWord* start = _hrm.reserved().start();
2053     HeapWord* end = _hrm.reserved().end();
2054     size_t granularity = HeapRegion::GrainBytes;
2055 
2056     _in_cset_fast_test.initialize(start, end, granularity);
2057     _humongous_reclaim_candidates.initialize(start, end, granularity);
2058   }
2059 
2060   // Create the ConcurrentMark data structure and thread.
2061   // (Must do this late, so that "max_regions" is defined.)
2062   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2063   if (_cm == NULL || !_cm->completed_initialization()) {
2064     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2065     return JNI_ENOMEM;
2066   }
2067   _cmThread = _cm->cmThread();
2068 
2069   // Initialize the from_card cache structure of HeapRegionRemSet.
2070   HeapRegionRemSet::init_heap(max_regions());
2071 
2072   // Now expand into the initial heap size.
2073   if (!expand(init_byte_size)) {
2074     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2075     return JNI_ENOMEM;
2076   }
2077 
2078   // Perform any initialization actions delegated to the policy.
2079   g1_policy()->init();
2080 
2081   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2082                                                SATB_Q_FL_lock,
2083                                                G1SATBProcessCompletedThreshold,
2084                                                Shared_SATB_Q_lock);
2085 
2086   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2087                                                 DirtyCardQ_CBL_mon,
2088                                                 DirtyCardQ_FL_lock,
2089                                                 concurrent_g1_refine()->yellow_zone(),
2090                                                 concurrent_g1_refine()->red_zone(),
2091                                                 Shared_DirtyCardQ_lock);
2092 
2093   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2094                                     DirtyCardQ_CBL_mon,
2095                                     DirtyCardQ_FL_lock,
2096                                     -1, // never trigger processing
2097                                     -1, // no limit on length
2098                                     Shared_DirtyCardQ_lock,
2099                                     &JavaThread::dirty_card_queue_set());
2100 
2101   // Initialize the card queue set used to hold cards containing
2102   // references into the collection set.
2103   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2104                                              DirtyCardQ_CBL_mon,
2105                                              DirtyCardQ_FL_lock,
2106                                              -1, // never trigger processing
2107                                              -1, // no limit on length
2108                                              Shared_DirtyCardQ_lock,
2109                                              &JavaThread::dirty_card_queue_set());
2110 
2111   // In case we're keeping closure specialization stats, initialize those
2112   // counts and that mechanism.
2113   SpecializationStats::clear();
2114 
2115   // Here we allocate the dummy HeapRegion that is required by the
2116   // G1AllocRegion class.
2117   HeapRegion* dummy_region = _hrm.get_dummy_region();
2118 
2119   // We'll re-use the same region whether the alloc region will
2120   // require BOT updates or not and, if it doesn't, then a non-young
2121   // region will complain that it cannot support allocations without
2122   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2123   dummy_region->set_eden();
2124   // Make sure it's full.
2125   dummy_region->set_top(dummy_region->end());
2126   G1AllocRegion::setup(this, dummy_region);
2127 
2128   _allocator->init_mutator_alloc_region();
2129 
2130   // Do create of the monitoring and management support so that
2131   // values in the heap have been properly initialized.
2132   _g1mm = new G1MonitoringSupport(this);
2133 
2134   G1StringDedup::initialize();
2135 
2136   return JNI_OK;
2137 }
2138 
2139 void G1CollectedHeap::stop() {
2140   // Stop all concurrent threads. We do this to make sure these threads
2141   // do not continue to execute and access resources (e.g. gclog_or_tty)
2142   // that are destroyed during shutdown.
2143   _cg1r->stop();
2144   _cmThread->stop();
2145   if (G1StringDedup::is_enabled()) {
2146     G1StringDedup::stop();
2147   }
2148 }
2149 
2150 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2151   return HeapRegion::max_region_size();
2152 }
2153 
2154 void G1CollectedHeap::ref_processing_init() {
2155   // Reference processing in G1 currently works as follows:
2156   //
2157   // * There are two reference processor instances. One is
2158   //   used to record and process discovered references
2159   //   during concurrent marking; the other is used to
2160   //   record and process references during STW pauses
2161   //   (both full and incremental).
2162   // * Both ref processors need to 'span' the entire heap as
2163   //   the regions in the collection set may be dotted around.
2164   //
2165   // * For the concurrent marking ref processor:
2166   //   * Reference discovery is enabled at initial marking.
2167   //   * Reference discovery is disabled and the discovered
2168   //     references processed etc during remarking.
2169   //   * Reference discovery is MT (see below).
2170   //   * Reference discovery requires a barrier (see below).
2171   //   * Reference processing may or may not be MT
2172   //     (depending on the value of ParallelRefProcEnabled
2173   //     and ParallelGCThreads).
2174   //   * A full GC disables reference discovery by the CM
2175   //     ref processor and abandons any entries on it's
2176   //     discovered lists.
2177   //
2178   // * For the STW processor:
2179   //   * Non MT discovery is enabled at the start of a full GC.
2180   //   * Processing and enqueueing during a full GC is non-MT.
2181   //   * During a full GC, references are processed after marking.
2182   //
2183   //   * Discovery (may or may not be MT) is enabled at the start
2184   //     of an incremental evacuation pause.
2185   //   * References are processed near the end of a STW evacuation pause.
2186   //   * For both types of GC:
2187   //     * Discovery is atomic - i.e. not concurrent.
2188   //     * Reference discovery will not need a barrier.
2189 
2190   SharedHeap::ref_processing_init();
2191   MemRegion mr = reserved_region();
2192 
2193   // Concurrent Mark ref processor
2194   _ref_processor_cm =
2195     new ReferenceProcessor(mr,    // span
2196                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2197                                 // mt processing
2198                            (int) ParallelGCThreads,
2199                                 // degree of mt processing
2200                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2201                                 // mt discovery
2202                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2203                                 // degree of mt discovery
2204                            false,
2205                                 // Reference discovery is not atomic
2206                            &_is_alive_closure_cm);
2207                                 // is alive closure
2208                                 // (for efficiency/performance)
2209 
2210   // STW ref processor
2211   _ref_processor_stw =
2212     new ReferenceProcessor(mr,    // span
2213                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2214                                 // mt processing
2215                            MAX2((int)ParallelGCThreads, 1),
2216                                 // degree of mt processing
2217                            (ParallelGCThreads > 1),
2218                                 // mt discovery
2219                            MAX2((int)ParallelGCThreads, 1),
2220                                 // degree of mt discovery
2221                            true,
2222                                 // Reference discovery is atomic
2223                            &_is_alive_closure_stw);
2224                                 // is alive closure
2225                                 // (for efficiency/performance)
2226 }
2227 
2228 size_t G1CollectedHeap::capacity() const {
2229   return _hrm.length() * HeapRegion::GrainBytes;
2230 }
2231 
2232 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2233   assert(!hr->continuesHumongous(), "pre-condition");
2234   hr->reset_gc_time_stamp();
2235   if (hr->startsHumongous()) {
2236     uint first_index = hr->hrm_index() + 1;
2237     uint last_index = hr->last_hc_index();
2238     for (uint i = first_index; i < last_index; i += 1) {
2239       HeapRegion* chr = region_at(i);
2240       assert(chr->continuesHumongous(), "sanity");
2241       chr->reset_gc_time_stamp();
2242     }
2243   }
2244 }
2245 
2246 #ifndef PRODUCT
2247 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2248 private:
2249   unsigned _gc_time_stamp;
2250   bool _failures;
2251 
2252 public:
2253   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2254     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2255 
2256   virtual bool doHeapRegion(HeapRegion* hr) {
2257     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2258     if (_gc_time_stamp != region_gc_time_stamp) {
2259       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2260                              "expected %d", HR_FORMAT_PARAMS(hr),
2261                              region_gc_time_stamp, _gc_time_stamp);
2262       _failures = true;
2263     }
2264     return false;
2265   }
2266 
2267   bool failures() { return _failures; }
2268 };
2269 
2270 void G1CollectedHeap::check_gc_time_stamps() {
2271   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2272   heap_region_iterate(&cl);
2273   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2274 }
2275 #endif // PRODUCT
2276 
2277 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2278                                                  DirtyCardQueue* into_cset_dcq,
2279                                                  bool concurrent,
2280                                                  uint worker_i) {
2281   // Clean cards in the hot card cache
2282   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2283   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2284 
2285   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2286   size_t n_completed_buffers = 0;
2287   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2288     n_completed_buffers++;
2289   }
2290   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2291   dcqs.clear_n_completed_buffers();
2292   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2293 }
2294 
2295 
2296 // Computes the sum of the storage used by the various regions.
2297 size_t G1CollectedHeap::used() const {
2298   return _allocator->used();
2299 }
2300 
2301 size_t G1CollectedHeap::used_unlocked() const {
2302   return _allocator->used_unlocked();
2303 }
2304 
2305 class SumUsedClosure: public HeapRegionClosure {
2306   size_t _used;
2307 public:
2308   SumUsedClosure() : _used(0) {}
2309   bool doHeapRegion(HeapRegion* r) {
2310     if (!r->continuesHumongous()) {
2311       _used += r->used();
2312     }
2313     return false;
2314   }
2315   size_t result() { return _used; }
2316 };
2317 
2318 size_t G1CollectedHeap::recalculate_used() const {
2319   double recalculate_used_start = os::elapsedTime();
2320 
2321   SumUsedClosure blk;
2322   heap_region_iterate(&blk);
2323 
2324   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2325   return blk.result();
2326 }
2327 
2328 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2329   switch (cause) {
2330     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2331     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2332     case GCCause::_g1_humongous_allocation: return true;
2333     case GCCause::_update_allocation_context_stats_inc: return true;
2334     case GCCause::_wb_conc_mark:            return true;
2335     default:                                return false;
2336   }
2337 }
2338 
2339 #ifndef PRODUCT
2340 void G1CollectedHeap::allocate_dummy_regions() {
2341   // Let's fill up most of the region
2342   size_t word_size = HeapRegion::GrainWords - 1024;
2343   // And as a result the region we'll allocate will be humongous.
2344   guarantee(isHumongous(word_size), "sanity");
2345 
2346   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2347     // Let's use the existing mechanism for the allocation
2348     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2349                                                  AllocationContext::system());
2350     if (dummy_obj != NULL) {
2351       MemRegion mr(dummy_obj, word_size);
2352       CollectedHeap::fill_with_object(mr);
2353     } else {
2354       // If we can't allocate once, we probably cannot allocate
2355       // again. Let's get out of the loop.
2356       break;
2357     }
2358   }
2359 }
2360 #endif // !PRODUCT
2361 
2362 void G1CollectedHeap::increment_old_marking_cycles_started() {
2363   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2364     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2365     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2366     _old_marking_cycles_started, _old_marking_cycles_completed));
2367 
2368   _old_marking_cycles_started++;
2369 }
2370 
2371 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2372   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2373 
2374   // We assume that if concurrent == true, then the caller is a
2375   // concurrent thread that was joined the Suspendible Thread
2376   // Set. If there's ever a cheap way to check this, we should add an
2377   // assert here.
2378 
2379   // Given that this method is called at the end of a Full GC or of a
2380   // concurrent cycle, and those can be nested (i.e., a Full GC can
2381   // interrupt a concurrent cycle), the number of full collections
2382   // completed should be either one (in the case where there was no
2383   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2384   // behind the number of full collections started.
2385 
2386   // This is the case for the inner caller, i.e. a Full GC.
2387   assert(concurrent ||
2388          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2389          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2390          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2391                  "is inconsistent with _old_marking_cycles_completed = %u",
2392                  _old_marking_cycles_started, _old_marking_cycles_completed));
2393 
2394   // This is the case for the outer caller, i.e. the concurrent cycle.
2395   assert(!concurrent ||
2396          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2397          err_msg("for outer caller (concurrent cycle): "
2398                  "_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   _old_marking_cycles_completed += 1;
2403 
2404   // We need to clear the "in_progress" flag in the CM thread before
2405   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2406   // is set) so that if a waiter requests another System.gc() it doesn't
2407   // incorrectly see that a marking cycle is still in progress.
2408   if (concurrent) {
2409     _cmThread->clear_in_progress();
2410   }
2411 
2412   // This notify_all() will ensure that a thread that called
2413   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2414   // and it's waiting for a full GC to finish will be woken up. It is
2415   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2416   FullGCCount_lock->notify_all();
2417 }
2418 
2419 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2420   _concurrent_cycle_started = true;
2421   _gc_timer_cm->register_gc_start(start_time);
2422 
2423   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2424   trace_heap_before_gc(_gc_tracer_cm);
2425 }
2426 
2427 void G1CollectedHeap::register_concurrent_cycle_end() {
2428   if (_concurrent_cycle_started) {
2429     if (_cm->has_aborted()) {
2430       _gc_tracer_cm->report_concurrent_mode_failure();
2431     }
2432 
2433     _gc_timer_cm->register_gc_end();
2434     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2435 
2436     // Clear state variables to prepare for the next concurrent cycle.
2437     _concurrent_cycle_started = false;
2438     _heap_summary_sent = false;
2439   }
2440 }
2441 
2442 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2443   if (_concurrent_cycle_started) {
2444     // This function can be called when:
2445     //  the cleanup pause is run
2446     //  the concurrent cycle is aborted before the cleanup pause.
2447     //  the concurrent cycle is aborted after the cleanup pause,
2448     //   but before the concurrent cycle end has been registered.
2449     // Make sure that we only send the heap information once.
2450     if (!_heap_summary_sent) {
2451       trace_heap_after_gc(_gc_tracer_cm);
2452       _heap_summary_sent = true;
2453     }
2454   }
2455 }
2456 
2457 G1YCType G1CollectedHeap::yc_type() {
2458   bool is_young = g1_policy()->gcs_are_young();
2459   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2460   bool is_during_mark = mark_in_progress();
2461 
2462   if (is_initial_mark) {
2463     return InitialMark;
2464   } else if (is_during_mark) {
2465     return DuringMark;
2466   } else if (is_young) {
2467     return Normal;
2468   } else {
2469     return Mixed;
2470   }
2471 }
2472 
2473 void G1CollectedHeap::collect(GCCause::Cause cause) {
2474   assert_heap_not_locked();
2475 
2476   uint gc_count_before;
2477   uint old_marking_count_before;
2478   uint full_gc_count_before;
2479   bool retry_gc;
2480 
2481   do {
2482     retry_gc = false;
2483 
2484     {
2485       MutexLocker ml(Heap_lock);
2486 
2487       // Read the GC count while holding the Heap_lock
2488       gc_count_before = total_collections();
2489       full_gc_count_before = total_full_collections();
2490       old_marking_count_before = _old_marking_cycles_started;
2491     }
2492 
2493     if (should_do_concurrent_full_gc(cause)) {
2494       // Schedule an initial-mark evacuation pause that will start a
2495       // concurrent cycle. We're setting word_size to 0 which means that
2496       // we are not requesting a post-GC allocation.
2497       VM_G1IncCollectionPause op(gc_count_before,
2498                                  0,     /* word_size */
2499                                  true,  /* should_initiate_conc_mark */
2500                                  g1_policy()->max_pause_time_ms(),
2501                                  cause);
2502       op.set_allocation_context(AllocationContext::current());
2503 
2504       VMThread::execute(&op);
2505       if (!op.pause_succeeded()) {
2506         if (old_marking_count_before == _old_marking_cycles_started) {
2507           retry_gc = op.should_retry_gc();
2508         } else {
2509           // A Full GC happened while we were trying to schedule the
2510           // initial-mark GC. No point in starting a new cycle given
2511           // that the whole heap was collected anyway.
2512         }
2513 
2514         if (retry_gc) {
2515           if (GC_locker::is_active_and_needs_gc()) {
2516             GC_locker::stall_until_clear();
2517           }
2518         }
2519       }
2520     } else {
2521       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2522           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2523 
2524         // Schedule a standard evacuation pause. We're setting word_size
2525         // to 0 which means that we are not requesting a post-GC allocation.
2526         VM_G1IncCollectionPause op(gc_count_before,
2527                                    0,     /* word_size */
2528                                    false, /* should_initiate_conc_mark */
2529                                    g1_policy()->max_pause_time_ms(),
2530                                    cause);
2531         VMThread::execute(&op);
2532       } else {
2533         // Schedule a Full GC.
2534         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2535         VMThread::execute(&op);
2536       }
2537     }
2538   } while (retry_gc);
2539 }
2540 
2541 bool G1CollectedHeap::is_in(const void* p) const {
2542   if (_hrm.reserved().contains(p)) {
2543     // Given that we know that p is in the reserved space,
2544     // heap_region_containing_raw() should successfully
2545     // return the containing region.
2546     HeapRegion* hr = heap_region_containing_raw(p);
2547     return hr->is_in(p);
2548   } else {
2549     return false;
2550   }
2551 }
2552 
2553 #ifdef ASSERT
2554 bool G1CollectedHeap::is_in_exact(const void* p) const {
2555   bool contains = reserved_region().contains(p);
2556   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2557   if (contains && available) {
2558     return true;
2559   } else {
2560     return false;
2561   }
2562 }
2563 #endif
2564 
2565 // Iteration functions.
2566 
2567 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2568 
2569 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2570   ExtendedOopClosure* _cl;
2571 public:
2572   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2573   bool doHeapRegion(HeapRegion* r) {
2574     if (!r->continuesHumongous()) {
2575       r->oop_iterate(_cl);
2576     }
2577     return false;
2578   }
2579 };
2580 
2581 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2582   IterateOopClosureRegionClosure blk(cl);
2583   heap_region_iterate(&blk);
2584 }
2585 
2586 // Iterates an ObjectClosure over all objects within a HeapRegion.
2587 
2588 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2589   ObjectClosure* _cl;
2590 public:
2591   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2592   bool doHeapRegion(HeapRegion* r) {
2593     if (! r->continuesHumongous()) {
2594       r->object_iterate(_cl);
2595     }
2596     return false;
2597   }
2598 };
2599 
2600 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2601   IterateObjectClosureRegionClosure blk(cl);
2602   heap_region_iterate(&blk);
2603 }
2604 
2605 // Calls a SpaceClosure on a HeapRegion.
2606 
2607 class SpaceClosureRegionClosure: public HeapRegionClosure {
2608   SpaceClosure* _cl;
2609 public:
2610   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2611   bool doHeapRegion(HeapRegion* r) {
2612     _cl->do_space(r);
2613     return false;
2614   }
2615 };
2616 
2617 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2618   SpaceClosureRegionClosure blk(cl);
2619   heap_region_iterate(&blk);
2620 }
2621 
2622 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2623   _hrm.iterate(cl);
2624 }
2625 
2626 void
2627 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2628                                                  uint worker_id,
2629                                                  uint num_workers,
2630                                                  jint claim_value) const {
2631   _hrm.par_iterate(cl, worker_id, num_workers, claim_value);
2632 }
2633 
2634 class ResetClaimValuesClosure: public HeapRegionClosure {
2635 public:
2636   bool doHeapRegion(HeapRegion* r) {
2637     r->set_claim_value(HeapRegion::InitialClaimValue);
2638     return false;
2639   }
2640 };
2641 
2642 void G1CollectedHeap::reset_heap_region_claim_values() {
2643   ResetClaimValuesClosure blk;
2644   heap_region_iterate(&blk);
2645 }
2646 
2647 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2648   ResetClaimValuesClosure blk;
2649   collection_set_iterate(&blk);
2650 }
2651 
2652 #ifdef ASSERT
2653 // This checks whether all regions in the heap have the correct claim
2654 // value. I also piggy-backed on this a check to ensure that the
2655 // humongous_start_region() information on "continues humongous"
2656 // regions is correct.
2657 
2658 class CheckClaimValuesClosure : public HeapRegionClosure {
2659 private:
2660   jint _claim_value;
2661   uint _failures;
2662   HeapRegion* _sh_region;
2663 
2664 public:
2665   CheckClaimValuesClosure(jint claim_value) :
2666     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2667   bool doHeapRegion(HeapRegion* r) {
2668     if (r->claim_value() != _claim_value) {
2669       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2670                              "claim value = %d, should be %d",
2671                              HR_FORMAT_PARAMS(r),
2672                              r->claim_value(), _claim_value);
2673       ++_failures;
2674     }
2675     if (!r->isHumongous()) {
2676       _sh_region = NULL;
2677     } else if (r->startsHumongous()) {
2678       _sh_region = r;
2679     } else if (r->continuesHumongous()) {
2680       if (r->humongous_start_region() != _sh_region) {
2681         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2682                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2683                                HR_FORMAT_PARAMS(r),
2684                                r->humongous_start_region(),
2685                                _sh_region);
2686         ++_failures;
2687       }
2688     }
2689     return false;
2690   }
2691   uint failures() { return _failures; }
2692 };
2693 
2694 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2695   CheckClaimValuesClosure cl(claim_value);
2696   heap_region_iterate(&cl);
2697   return cl.failures() == 0;
2698 }
2699 
2700 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2701 private:
2702   jint _claim_value;
2703   uint _failures;
2704 
2705 public:
2706   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2707     _claim_value(claim_value), _failures(0) { }
2708 
2709   uint failures() { return _failures; }
2710 
2711   bool doHeapRegion(HeapRegion* hr) {
2712     assert(hr->in_collection_set(), "how?");
2713     assert(!hr->isHumongous(), "H-region in CSet");
2714     if (hr->claim_value() != _claim_value) {
2715       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2716                              "claim value = %d, should be %d",
2717                              HR_FORMAT_PARAMS(hr),
2718                              hr->claim_value(), _claim_value);
2719       _failures += 1;
2720     }
2721     return false;
2722   }
2723 };
2724 
2725 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2726   CheckClaimValuesInCSetHRClosure cl(claim_value);
2727   collection_set_iterate(&cl);
2728   return cl.failures() == 0;
2729 }
2730 #endif // ASSERT
2731 
2732 // Clear the cached CSet starting regions and (more importantly)
2733 // the time stamps. Called when we reset the GC time stamp.
2734 void G1CollectedHeap::clear_cset_start_regions() {
2735   assert(_worker_cset_start_region != NULL, "sanity");
2736   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2737 
2738   int n_queues = MAX2((int)ParallelGCThreads, 1);
2739   for (int i = 0; i < n_queues; i++) {
2740     _worker_cset_start_region[i] = NULL;
2741     _worker_cset_start_region_time_stamp[i] = 0;
2742   }
2743 }
2744 
2745 // Given the id of a worker, obtain or calculate a suitable
2746 // starting region for iterating over the current collection set.
2747 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2748   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2749 
2750   HeapRegion* result = NULL;
2751   unsigned gc_time_stamp = get_gc_time_stamp();
2752 
2753   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2754     // Cached starting region for current worker was set
2755     // during the current pause - so it's valid.
2756     // Note: the cached starting heap region may be NULL
2757     // (when the collection set is empty).
2758     result = _worker_cset_start_region[worker_i];
2759     assert(result == NULL || result->in_collection_set(), "sanity");
2760     return result;
2761   }
2762 
2763   // The cached entry was not valid so let's calculate
2764   // a suitable starting heap region for this worker.
2765 
2766   // We want the parallel threads to start their collection
2767   // set iteration at different collection set regions to
2768   // avoid contention.
2769   // If we have:
2770   //          n collection set regions
2771   //          p threads
2772   // Then thread t will start at region floor ((t * n) / p)
2773 
2774   result = g1_policy()->collection_set();
2775   if (G1CollectedHeap::use_parallel_gc_threads()) {
2776     uint cs_size = g1_policy()->cset_region_length();
2777     uint active_workers = workers()->active_workers();
2778     assert(UseDynamicNumberOfGCThreads ||
2779              active_workers == workers()->total_workers(),
2780              "Unless dynamic should use total workers");
2781 
2782     uint end_ind   = (cs_size * worker_i) / active_workers;
2783     uint start_ind = 0;
2784 
2785     if (worker_i > 0 &&
2786         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2787       // Previous workers starting region is valid
2788       // so let's iterate from there
2789       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2790       result = _worker_cset_start_region[worker_i - 1];
2791     }
2792 
2793     for (uint i = start_ind; i < end_ind; i++) {
2794       result = result->next_in_collection_set();
2795     }
2796   }
2797 
2798   // Note: the calculated starting heap region may be NULL
2799   // (when the collection set is empty).
2800   assert(result == NULL || result->in_collection_set(), "sanity");
2801   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2802          "should be updated only once per pause");
2803   _worker_cset_start_region[worker_i] = result;
2804   OrderAccess::storestore();
2805   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2806   return result;
2807 }
2808 
2809 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2810   HeapRegion* r = g1_policy()->collection_set();
2811   while (r != NULL) {
2812     HeapRegion* next = r->next_in_collection_set();
2813     if (cl->doHeapRegion(r)) {
2814       cl->incomplete();
2815       return;
2816     }
2817     r = next;
2818   }
2819 }
2820 
2821 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2822                                                   HeapRegionClosure *cl) {
2823   if (r == NULL) {
2824     // The CSet is empty so there's nothing to do.
2825     return;
2826   }
2827 
2828   assert(r->in_collection_set(),
2829          "Start region must be a member of the collection set.");
2830   HeapRegion* cur = r;
2831   while (cur != NULL) {
2832     HeapRegion* next = cur->next_in_collection_set();
2833     if (cl->doHeapRegion(cur) && false) {
2834       cl->incomplete();
2835       return;
2836     }
2837     cur = next;
2838   }
2839   cur = g1_policy()->collection_set();
2840   while (cur != r) {
2841     HeapRegion* next = cur->next_in_collection_set();
2842     if (cl->doHeapRegion(cur) && false) {
2843       cl->incomplete();
2844       return;
2845     }
2846     cur = next;
2847   }
2848 }
2849 
2850 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2851   HeapRegion* result = _hrm.next_region_in_heap(from);
2852   while (result != NULL && result->isHumongous()) {
2853     result = _hrm.next_region_in_heap(result);
2854   }
2855   return result;
2856 }
2857 
2858 Space* G1CollectedHeap::space_containing(const void* addr) const {
2859   return heap_region_containing(addr);
2860 }
2861 
2862 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2863   Space* sp = space_containing(addr);
2864   return sp->block_start(addr);
2865 }
2866 
2867 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2868   Space* sp = space_containing(addr);
2869   return sp->block_size(addr);
2870 }
2871 
2872 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2873   Space* sp = space_containing(addr);
2874   return sp->block_is_obj(addr);
2875 }
2876 
2877 bool G1CollectedHeap::supports_tlab_allocation() const {
2878   return true;
2879 }
2880 
2881 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2882   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2883 }
2884 
2885 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2886   return young_list()->eden_used_bytes();
2887 }
2888 
2889 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2890 // must be smaller than the humongous object limit.
2891 size_t G1CollectedHeap::max_tlab_size() const {
2892   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2893 }
2894 
2895 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2896   // Return the remaining space in the cur alloc region, but not less than
2897   // the min TLAB size.
2898 
2899   // Also, this value can be at most the humongous object threshold,
2900   // since we can't allow tlabs to grow big enough to accommodate
2901   // humongous objects.
2902 
2903   HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2904   size_t max_tlab = max_tlab_size() * wordSize;
2905   if (hr == NULL) {
2906     return max_tlab;
2907   } else {
2908     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2909   }
2910 }
2911 
2912 size_t G1CollectedHeap::max_capacity() const {
2913   return _hrm.reserved().byte_size();
2914 }
2915 
2916 jlong G1CollectedHeap::millis_since_last_gc() {
2917   // assert(false, "NYI");
2918   return 0;
2919 }
2920 
2921 void G1CollectedHeap::prepare_for_verify() {
2922   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2923     ensure_parsability(false);
2924   }
2925   g1_rem_set()->prepare_for_verify();
2926 }
2927 
2928 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2929                                               VerifyOption vo) {
2930   switch (vo) {
2931   case VerifyOption_G1UsePrevMarking:
2932     return hr->obj_allocated_since_prev_marking(obj);
2933   case VerifyOption_G1UseNextMarking:
2934     return hr->obj_allocated_since_next_marking(obj);
2935   case VerifyOption_G1UseMarkWord:
2936     return false;
2937   default:
2938     ShouldNotReachHere();
2939   }
2940   return false; // keep some compilers happy
2941 }
2942 
2943 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2944   switch (vo) {
2945   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2946   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2947   case VerifyOption_G1UseMarkWord:    return NULL;
2948   default:                            ShouldNotReachHere();
2949   }
2950   return NULL; // keep some compilers happy
2951 }
2952 
2953 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2954   switch (vo) {
2955   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2956   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2957   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2958   default:                            ShouldNotReachHere();
2959   }
2960   return false; // keep some compilers happy
2961 }
2962 
2963 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2964   switch (vo) {
2965   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2966   case VerifyOption_G1UseNextMarking: return "NTAMS";
2967   case VerifyOption_G1UseMarkWord:    return "NONE";
2968   default:                            ShouldNotReachHere();
2969   }
2970   return NULL; // keep some compilers happy
2971 }
2972 
2973 class VerifyRootsClosure: public OopClosure {
2974 private:
2975   G1CollectedHeap* _g1h;
2976   VerifyOption     _vo;
2977   bool             _failures;
2978 public:
2979   // _vo == UsePrevMarking -> use "prev" marking information,
2980   // _vo == UseNextMarking -> use "next" marking information,
2981   // _vo == UseMarkWord    -> use mark word from object header.
2982   VerifyRootsClosure(VerifyOption vo) :
2983     _g1h(G1CollectedHeap::heap()),
2984     _vo(vo),
2985     _failures(false) { }
2986 
2987   bool failures() { return _failures; }
2988 
2989   template <class T> void do_oop_nv(T* p) {
2990     T heap_oop = oopDesc::load_heap_oop(p);
2991     if (!oopDesc::is_null(heap_oop)) {
2992       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2993       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2994         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2995                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2996         if (_vo == VerifyOption_G1UseMarkWord) {
2997           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2998         }
2999         obj->print_on(gclog_or_tty);
3000         _failures = true;
3001       }
3002     }
3003   }
3004 
3005   void do_oop(oop* p)       { do_oop_nv(p); }
3006   void do_oop(narrowOop* p) { do_oop_nv(p); }
3007 };
3008 
3009 class G1VerifyCodeRootOopClosure: public OopClosure {
3010   G1CollectedHeap* _g1h;
3011   OopClosure* _root_cl;
3012   nmethod* _nm;
3013   VerifyOption _vo;
3014   bool _failures;
3015 
3016   template <class T> void do_oop_work(T* p) {
3017     // First verify that this root is live
3018     _root_cl->do_oop(p);
3019 
3020     if (!G1VerifyHeapRegionCodeRoots) {
3021       // We're not verifying the code roots attached to heap region.
3022       return;
3023     }
3024 
3025     // Don't check the code roots during marking verification in a full GC
3026     if (_vo == VerifyOption_G1UseMarkWord) {
3027       return;
3028     }
3029 
3030     // Now verify that the current nmethod (which contains p) is
3031     // in the code root list of the heap region containing the
3032     // object referenced by p.
3033 
3034     T heap_oop = oopDesc::load_heap_oop(p);
3035     if (!oopDesc::is_null(heap_oop)) {
3036       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3037 
3038       // Now fetch the region containing the object
3039       HeapRegion* hr = _g1h->heap_region_containing(obj);
3040       HeapRegionRemSet* hrrs = hr->rem_set();
3041       // Verify that the strong code root list for this region
3042       // contains the nmethod
3043       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3044         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3045                               "from nmethod "PTR_FORMAT" not in strong "
3046                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3047                               p, _nm, hr->bottom(), hr->end());
3048         _failures = true;
3049       }
3050     }
3051   }
3052 
3053 public:
3054   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3055     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3056 
3057   void do_oop(oop* p) { do_oop_work(p); }
3058   void do_oop(narrowOop* p) { do_oop_work(p); }
3059 
3060   void set_nmethod(nmethod* nm) { _nm = nm; }
3061   bool failures() { return _failures; }
3062 };
3063 
3064 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3065   G1VerifyCodeRootOopClosure* _oop_cl;
3066 
3067 public:
3068   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3069     _oop_cl(oop_cl) {}
3070 
3071   void do_code_blob(CodeBlob* cb) {
3072     nmethod* nm = cb->as_nmethod_or_null();
3073     if (nm != NULL) {
3074       _oop_cl->set_nmethod(nm);
3075       nm->oops_do(_oop_cl);
3076     }
3077   }
3078 };
3079 
3080 class YoungRefCounterClosure : public OopClosure {
3081   G1CollectedHeap* _g1h;
3082   int              _count;
3083  public:
3084   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3085   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3086   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3087 
3088   int count() { return _count; }
3089   void reset_count() { _count = 0; };
3090 };
3091 
3092 class VerifyKlassClosure: public KlassClosure {
3093   YoungRefCounterClosure _young_ref_counter_closure;
3094   OopClosure *_oop_closure;
3095  public:
3096   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3097   void do_klass(Klass* k) {
3098     k->oops_do(_oop_closure);
3099 
3100     _young_ref_counter_closure.reset_count();
3101     k->oops_do(&_young_ref_counter_closure);
3102     if (_young_ref_counter_closure.count() > 0) {
3103       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3104     }
3105   }
3106 };
3107 
3108 class VerifyLivenessOopClosure: public OopClosure {
3109   G1CollectedHeap* _g1h;
3110   VerifyOption _vo;
3111 public:
3112   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3113     _g1h(g1h), _vo(vo)
3114   { }
3115   void do_oop(narrowOop *p) { do_oop_work(p); }
3116   void do_oop(      oop *p) { do_oop_work(p); }
3117 
3118   template <class T> void do_oop_work(T *p) {
3119     oop obj = oopDesc::load_decode_heap_oop(p);
3120     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3121               "Dead object referenced by a not dead object");
3122   }
3123 };
3124 
3125 class VerifyObjsInRegionClosure: public ObjectClosure {
3126 private:
3127   G1CollectedHeap* _g1h;
3128   size_t _live_bytes;
3129   HeapRegion *_hr;
3130   VerifyOption _vo;
3131 public:
3132   // _vo == UsePrevMarking -> use "prev" marking information,
3133   // _vo == UseNextMarking -> use "next" marking information,
3134   // _vo == UseMarkWord    -> use mark word from object header.
3135   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3136     : _live_bytes(0), _hr(hr), _vo(vo) {
3137     _g1h = G1CollectedHeap::heap();
3138   }
3139   void do_object(oop o) {
3140     VerifyLivenessOopClosure isLive(_g1h, _vo);
3141     assert(o != NULL, "Huh?");
3142     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3143       // If the object is alive according to the mark word,
3144       // then verify that the marking information agrees.
3145       // Note we can't verify the contra-positive of the
3146       // above: if the object is dead (according to the mark
3147       // word), it may not be marked, or may have been marked
3148       // but has since became dead, or may have been allocated
3149       // since the last marking.
3150       if (_vo == VerifyOption_G1UseMarkWord) {
3151         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3152       }
3153 
3154       o->oop_iterate_no_header(&isLive);
3155       if (!_hr->obj_allocated_since_prev_marking(o)) {
3156         size_t obj_size = o->size();    // Make sure we don't overflow
3157         _live_bytes += (obj_size * HeapWordSize);
3158       }
3159     }
3160   }
3161   size_t live_bytes() { return _live_bytes; }
3162 };
3163 
3164 class PrintObjsInRegionClosure : public ObjectClosure {
3165   HeapRegion *_hr;
3166   G1CollectedHeap *_g1;
3167 public:
3168   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3169     _g1 = G1CollectedHeap::heap();
3170   };
3171 
3172   void do_object(oop o) {
3173     if (o != NULL) {
3174       HeapWord *start = (HeapWord *) o;
3175       size_t word_sz = o->size();
3176       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3177                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3178                           (void*) o, word_sz,
3179                           _g1->isMarkedPrev(o),
3180                           _g1->isMarkedNext(o),
3181                           _hr->obj_allocated_since_prev_marking(o));
3182       HeapWord *end = start + word_sz;
3183       HeapWord *cur;
3184       int *val;
3185       for (cur = start; cur < end; cur++) {
3186         val = (int *) cur;
3187         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3188       }
3189     }
3190   }
3191 };
3192 
3193 class VerifyRegionClosure: public HeapRegionClosure {
3194 private:
3195   bool             _par;
3196   VerifyOption     _vo;
3197   bool             _failures;
3198 public:
3199   // _vo == UsePrevMarking -> use "prev" marking information,
3200   // _vo == UseNextMarking -> use "next" marking information,
3201   // _vo == UseMarkWord    -> use mark word from object header.
3202   VerifyRegionClosure(bool par, VerifyOption vo)
3203     : _par(par),
3204       _vo(vo),
3205       _failures(false) {}
3206 
3207   bool failures() {
3208     return _failures;
3209   }
3210 
3211   bool doHeapRegion(HeapRegion* r) {
3212     if (!r->continuesHumongous()) {
3213       bool failures = false;
3214       r->verify(_vo, &failures);
3215       if (failures) {
3216         _failures = true;
3217       } else {
3218         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3219         r->object_iterate(&not_dead_yet_cl);
3220         if (_vo != VerifyOption_G1UseNextMarking) {
3221           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3222             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3223                                    "max_live_bytes "SIZE_FORMAT" "
3224                                    "< calculated "SIZE_FORMAT,
3225                                    r->bottom(), r->end(),
3226                                    r->max_live_bytes(),
3227                                  not_dead_yet_cl.live_bytes());
3228             _failures = true;
3229           }
3230         } else {
3231           // When vo == UseNextMarking we cannot currently do a sanity
3232           // check on the live bytes as the calculation has not been
3233           // finalized yet.
3234         }
3235       }
3236     }
3237     return false; // stop the region iteration if we hit a failure
3238   }
3239 };
3240 
3241 // This is the task used for parallel verification of the heap regions
3242 
3243 class G1ParVerifyTask: public AbstractGangTask {
3244 private:
3245   G1CollectedHeap* _g1h;
3246   VerifyOption     _vo;
3247   bool             _failures;
3248 
3249 public:
3250   // _vo == UsePrevMarking -> use "prev" marking information,
3251   // _vo == UseNextMarking -> use "next" marking information,
3252   // _vo == UseMarkWord    -> use mark word from object header.
3253   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3254     AbstractGangTask("Parallel verify task"),
3255     _g1h(g1h),
3256     _vo(vo),
3257     _failures(false) { }
3258 
3259   bool failures() {
3260     return _failures;
3261   }
3262 
3263   void work(uint worker_id) {
3264     HandleMark hm;
3265     VerifyRegionClosure blk(true, _vo);
3266     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3267                                           _g1h->workers()->active_workers(),
3268                                           HeapRegion::ParVerifyClaimValue);
3269     if (blk.failures()) {
3270       _failures = true;
3271     }
3272   }
3273 };
3274 
3275 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3276   if (SafepointSynchronize::is_at_safepoint()) {
3277     assert(Thread::current()->is_VM_thread(),
3278            "Expected to be executed serially by the VM thread at this point");
3279 
3280     if (!silent) { gclog_or_tty->print("Roots "); }
3281     VerifyRootsClosure rootsCl(vo);
3282     VerifyKlassClosure klassCl(this, &rootsCl);
3283     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3284 
3285     // We apply the relevant closures to all the oops in the
3286     // system dictionary, class loader data graph, the string table
3287     // and the nmethods in the code cache.
3288     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3289     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3290 
3291     {
3292       G1RootProcessor root_processor(this);
3293       root_processor.process_all_roots(&rootsCl,
3294                                        &cldCl,
3295                                        &blobsCl);
3296     }
3297 
3298     bool failures = rootsCl.failures() || codeRootsCl.failures();
3299 
3300     if (vo != VerifyOption_G1UseMarkWord) {
3301       // If we're verifying during a full GC then the region sets
3302       // will have been torn down at the start of the GC. Therefore
3303       // verifying the region sets will fail. So we only verify
3304       // the region sets when not in a full GC.
3305       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3306       verify_region_sets();
3307     }
3308 
3309     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3310     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3311       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3312              "sanity check");
3313 
3314       G1ParVerifyTask task(this, vo);
3315       assert(UseDynamicNumberOfGCThreads ||
3316         workers()->active_workers() == workers()->total_workers(),
3317         "If not dynamic should be using all the workers");
3318       int n_workers = workers()->active_workers();
3319       set_par_threads(n_workers);
3320       workers()->run_task(&task);
3321       set_par_threads(0);
3322       if (task.failures()) {
3323         failures = true;
3324       }
3325 
3326       // Checks that the expected amount of parallel work was done.
3327       // The implication is that n_workers is > 0.
3328       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3329              "sanity check");
3330 
3331       reset_heap_region_claim_values();
3332 
3333       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3334              "sanity check");
3335     } else {
3336       VerifyRegionClosure blk(false, vo);
3337       heap_region_iterate(&blk);
3338       if (blk.failures()) {
3339         failures = true;
3340       }
3341     }
3342     if (!silent) gclog_or_tty->print("RemSet ");
3343     rem_set()->verify();
3344 
3345     if (G1StringDedup::is_enabled()) {
3346       if (!silent) gclog_or_tty->print("StrDedup ");
3347       G1StringDedup::verify();
3348     }
3349 
3350     if (failures) {
3351       gclog_or_tty->print_cr("Heap:");
3352       // It helps to have the per-region information in the output to
3353       // help us track down what went wrong. This is why we call
3354       // print_extended_on() instead of print_on().
3355       print_extended_on(gclog_or_tty);
3356       gclog_or_tty->cr();
3357 #ifndef PRODUCT
3358       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3359         concurrent_mark()->print_reachable("at-verification-failure",
3360                                            vo, false /* all */);
3361       }
3362 #endif
3363       gclog_or_tty->flush();
3364     }
3365     guarantee(!failures, "there should not have been any failures");
3366   } else {
3367     if (!silent) {
3368       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3369       if (G1StringDedup::is_enabled()) {
3370         gclog_or_tty->print(", StrDedup");
3371       }
3372       gclog_or_tty->print(") ");
3373     }
3374   }
3375 }
3376 
3377 void G1CollectedHeap::verify(bool silent) {
3378   verify(silent, VerifyOption_G1UsePrevMarking);
3379 }
3380 
3381 double G1CollectedHeap::verify(bool guard, const char* msg) {
3382   double verify_time_ms = 0.0;
3383 
3384   if (guard && total_collections() >= VerifyGCStartAt) {
3385     double verify_start = os::elapsedTime();
3386     HandleMark hm;  // Discard invalid handles created during verification
3387     prepare_for_verify();
3388     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3389     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3390   }
3391 
3392   return verify_time_ms;
3393 }
3394 
3395 void G1CollectedHeap::verify_before_gc() {
3396   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3397   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3398 }
3399 
3400 void G1CollectedHeap::verify_after_gc() {
3401   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3402   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3403 }
3404 
3405 class PrintRegionClosure: public HeapRegionClosure {
3406   outputStream* _st;
3407 public:
3408   PrintRegionClosure(outputStream* st) : _st(st) {}
3409   bool doHeapRegion(HeapRegion* r) {
3410     r->print_on(_st);
3411     return false;
3412   }
3413 };
3414 
3415 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3416                                        const HeapRegion* hr,
3417                                        const VerifyOption vo) const {
3418   switch (vo) {
3419   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3420   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3421   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3422   default:                            ShouldNotReachHere();
3423   }
3424   return false; // keep some compilers happy
3425 }
3426 
3427 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3428                                        const VerifyOption vo) const {
3429   switch (vo) {
3430   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3431   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3432   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3433   default:                            ShouldNotReachHere();
3434   }
3435   return false; // keep some compilers happy
3436 }
3437 
3438 void G1CollectedHeap::print_on(outputStream* st) const {
3439   st->print(" %-20s", "garbage-first heap");
3440   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3441             capacity()/K, used_unlocked()/K);
3442   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3443             _hrm.reserved().start(),
3444             _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3445             _hrm.reserved().end());
3446   st->cr();
3447   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3448   uint young_regions = _young_list->length();
3449   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3450             (size_t) young_regions * HeapRegion::GrainBytes / K);
3451   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3452   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3453             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3454   st->cr();
3455   MetaspaceAux::print_on(st);
3456 }
3457 
3458 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3459   print_on(st);
3460 
3461   // Print the per-region information.
3462   st->cr();
3463   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3464                "HS=humongous(starts), HC=humongous(continues), "
3465                "CS=collection set, F=free, TS=gc time stamp, "
3466                "PTAMS=previous top-at-mark-start, "
3467                "NTAMS=next top-at-mark-start)");
3468   PrintRegionClosure blk(st);
3469   heap_region_iterate(&blk);
3470 }
3471 
3472 void G1CollectedHeap::print_on_error(outputStream* st) const {
3473   this->CollectedHeap::print_on_error(st);
3474 
3475   if (_cm != NULL) {
3476     st->cr();
3477     _cm->print_on_error(st);
3478   }
3479 }
3480 
3481 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3482   if (G1CollectedHeap::use_parallel_gc_threads()) {
3483     workers()->print_worker_threads_on(st);
3484   }
3485   _cmThread->print_on(st);
3486   st->cr();
3487   _cm->print_worker_threads_on(st);
3488   _cg1r->print_worker_threads_on(st);
3489   if (G1StringDedup::is_enabled()) {
3490     G1StringDedup::print_worker_threads_on(st);
3491   }
3492 }
3493 
3494 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3495   if (G1CollectedHeap::use_parallel_gc_threads()) {
3496     workers()->threads_do(tc);
3497   }
3498   tc->do_thread(_cmThread);
3499   _cg1r->threads_do(tc);
3500   if (G1StringDedup::is_enabled()) {
3501     G1StringDedup::threads_do(tc);
3502   }
3503 }
3504 
3505 void G1CollectedHeap::print_tracing_info() const {
3506   // We'll overload this to mean "trace GC pause statistics."
3507   if (TraceGen0Time || TraceGen1Time) {
3508     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3509     // to that.
3510     g1_policy()->print_tracing_info();
3511   }
3512   if (G1SummarizeRSetStats) {
3513     g1_rem_set()->print_summary_info();
3514   }
3515   if (G1SummarizeConcMark) {
3516     concurrent_mark()->print_summary_info();
3517   }
3518   g1_policy()->print_yg_surv_rate_info();
3519   SpecializationStats::print();
3520 }
3521 
3522 #ifndef PRODUCT
3523 // Helpful for debugging RSet issues.
3524 
3525 class PrintRSetsClosure : public HeapRegionClosure {
3526 private:
3527   const char* _msg;
3528   size_t _occupied_sum;
3529 
3530 public:
3531   bool doHeapRegion(HeapRegion* r) {
3532     HeapRegionRemSet* hrrs = r->rem_set();
3533     size_t occupied = hrrs->occupied();
3534     _occupied_sum += occupied;
3535 
3536     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3537                            HR_FORMAT_PARAMS(r));
3538     if (occupied == 0) {
3539       gclog_or_tty->print_cr("  RSet is empty");
3540     } else {
3541       hrrs->print();
3542     }
3543     gclog_or_tty->print_cr("----------");
3544     return false;
3545   }
3546 
3547   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3548     gclog_or_tty->cr();
3549     gclog_or_tty->print_cr("========================================");
3550     gclog_or_tty->print_cr("%s", msg);
3551     gclog_or_tty->cr();
3552   }
3553 
3554   ~PrintRSetsClosure() {
3555     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3556     gclog_or_tty->print_cr("========================================");
3557     gclog_or_tty->cr();
3558   }
3559 };
3560 
3561 void G1CollectedHeap::print_cset_rsets() {
3562   PrintRSetsClosure cl("Printing CSet RSets");
3563   collection_set_iterate(&cl);
3564 }
3565 
3566 void G1CollectedHeap::print_all_rsets() {
3567   PrintRSetsClosure cl("Printing All RSets");;
3568   heap_region_iterate(&cl);
3569 }
3570 #endif // PRODUCT
3571 
3572 G1CollectedHeap* G1CollectedHeap::heap() {
3573   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3574          "not a garbage-first heap");
3575   return _g1h;
3576 }
3577 
3578 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3579   // always_do_update_barrier = false;
3580   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3581   // Fill TLAB's and such
3582   accumulate_statistics_all_tlabs();
3583   ensure_parsability(true);
3584 
3585   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3586       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3587     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3588   }
3589 }
3590 
3591 void G1CollectedHeap::gc_epilogue(bool full) {
3592 
3593   if (G1SummarizeRSetStats &&
3594       (G1SummarizeRSetStatsPeriod > 0) &&
3595       // we are at the end of the GC. Total collections has already been increased.
3596       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3597     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3598   }
3599 
3600   // FIXME: what is this about?
3601   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3602   // is set.
3603   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3604                         "derived pointer present"));
3605   // always_do_update_barrier = true;
3606 
3607   resize_all_tlabs();
3608   allocation_context_stats().update(full);
3609 
3610   // We have just completed a GC. Update the soft reference
3611   // policy with the new heap occupancy
3612   Universe::update_heap_info_at_gc();
3613 }
3614 
3615 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3616                                                uint gc_count_before,
3617                                                bool* succeeded,
3618                                                GCCause::Cause gc_cause) {
3619   assert_heap_not_locked_and_not_at_safepoint();
3620   g1_policy()->record_stop_world_start();
3621   VM_G1IncCollectionPause op(gc_count_before,
3622                              word_size,
3623                              false, /* should_initiate_conc_mark */
3624                              g1_policy()->max_pause_time_ms(),
3625                              gc_cause);
3626 
3627   op.set_allocation_context(AllocationContext::current());
3628   VMThread::execute(&op);
3629 
3630   HeapWord* result = op.result();
3631   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3632   assert(result == NULL || ret_succeeded,
3633          "the result should be NULL if the VM did not succeed");
3634   *succeeded = ret_succeeded;
3635 
3636   assert_heap_not_locked();
3637   return result;
3638 }
3639 
3640 void
3641 G1CollectedHeap::doConcurrentMark() {
3642   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3643   if (!_cmThread->in_progress()) {
3644     _cmThread->set_started();
3645     CGC_lock->notify();
3646   }
3647 }
3648 
3649 size_t G1CollectedHeap::pending_card_num() {
3650   size_t extra_cards = 0;
3651   JavaThread *curr = Threads::first();
3652   while (curr != NULL) {
3653     DirtyCardQueue& dcq = curr->dirty_card_queue();
3654     extra_cards += dcq.size();
3655     curr = curr->next();
3656   }
3657   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3658   size_t buffer_size = dcqs.buffer_size();
3659   size_t buffer_num = dcqs.completed_buffers_num();
3660 
3661   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3662   // in bytes - not the number of 'entries'. We need to convert
3663   // into a number of cards.
3664   return (buffer_size * buffer_num + extra_cards) / oopSize;
3665 }
3666 
3667 size_t G1CollectedHeap::cards_scanned() {
3668   return g1_rem_set()->cardsScanned();
3669 }
3670 
3671 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3672  private:
3673   size_t _total_humongous;
3674   size_t _candidate_humongous;
3675 
3676   DirtyCardQueue _dcq;
3677 
3678   // We don't nominate objects with many remembered set entries, on
3679   // the assumption that such objects are likely still live.
3680   bool is_remset_small(HeapRegion* region) const {
3681     HeapRegionRemSet* const rset = region->rem_set();
3682     return G1EagerReclaimHumongousObjectsWithStaleRefs
3683       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3684       : rset->is_empty();
3685   }
3686 
3687   bool is_typeArray_region(HeapRegion* region) const {
3688     return oop(region->bottom())->is_typeArray();
3689   }
3690 
3691   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3692     assert(region->startsHumongous(), "Must start a humongous object");
3693 
3694     // Candidate selection must satisfy the following constraints
3695     // while concurrent marking is in progress:
3696     //
3697     // * In order to maintain SATB invariants, an object must not be
3698     // reclaimed if it was allocated before the start of marking and
3699     // has not had its references scanned.  Such an object must have
3700     // its references (including type metadata) scanned to ensure no
3701     // live objects are missed by the marking process.  Objects
3702     // allocated after the start of concurrent marking don't need to
3703     // be scanned.
3704     //
3705     // * An object must not be reclaimed if it is on the concurrent
3706     // mark stack.  Objects allocated after the start of concurrent
3707     // marking are never pushed on the mark stack.
3708     //
3709     // Nominating only objects allocated after the start of concurrent
3710     // marking is sufficient to meet both constraints.  This may miss
3711     // some objects that satisfy the constraints, but the marking data
3712     // structures don't support efficiently performing the needed
3713     // additional tests or scrubbing of the mark stack.
3714     //
3715     // However, we presently only nominate is_typeArray() objects.
3716     // A humongous object containing references induces remembered
3717     // set entries on other regions.  In order to reclaim such an
3718     // object, those remembered sets would need to be cleaned up.
3719     //
3720     // We also treat is_typeArray() objects specially, allowing them
3721     // to be reclaimed even if allocated before the start of
3722     // concurrent mark.  For this we rely on mark stack insertion to
3723     // exclude is_typeArray() objects, preventing reclaiming an object
3724     // that is in the mark stack.  We also rely on the metadata for
3725     // such objects to be built-in and so ensured to be kept live.
3726     // Frequent allocation and drop of large binary blobs is an
3727     // important use case for eager reclaim, and this special handling
3728     // may reduce needed headroom.
3729 
3730     return is_typeArray_region(region) && is_remset_small(region);
3731   }
3732 
3733  public:
3734   RegisterHumongousWithInCSetFastTestClosure()
3735   : _total_humongous(0),
3736     _candidate_humongous(0),
3737     _dcq(&JavaThread::dirty_card_queue_set()) {
3738   }
3739 
3740   virtual bool doHeapRegion(HeapRegion* r) {
3741     if (!r->startsHumongous()) {
3742       return false;
3743     }
3744     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3745 
3746     bool is_candidate = humongous_region_is_candidate(g1h, r);
3747     uint rindex = r->hrm_index();
3748     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3749     if (is_candidate) {
3750       _candidate_humongous++;
3751       g1h->register_humongous_region_with_in_cset_fast_test(rindex);
3752       // Is_candidate already filters out humongous object with large remembered sets.
3753       // If we have a humongous object with a few remembered sets, we simply flush these
3754       // remembered set entries into the DCQS. That will result in automatic
3755       // re-evaluation of their remembered set entries during the following evacuation
3756       // phase.
3757       if (!r->rem_set()->is_empty()) {
3758         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3759                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3760         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3761         HeapRegionRemSetIterator hrrs(r->rem_set());
3762         size_t card_index;
3763         while (hrrs.has_next(card_index)) {
3764           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3765           if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3766             *card_ptr = CardTableModRefBS::dirty_card_val();
3767             _dcq.enqueue(card_ptr);
3768           }
3769         }
3770         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3771                err_msg("Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3772                hrrs.n_yielded(), r->rem_set()->occupied()));
3773         r->rem_set()->clear_locked();
3774       }
3775       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3776     }
3777     _total_humongous++;
3778 
3779     return false;
3780   }
3781 
3782   size_t total_humongous() const { return _total_humongous; }
3783   size_t candidate_humongous() const { return _candidate_humongous; }
3784 
3785   void flush_rem_set_entries() { _dcq.flush(); }
3786 };
3787 
3788 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3789   if (!G1EagerReclaimHumongousObjects) {
3790     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3791     return;
3792   }
3793   double time = os::elapsed_counter();
3794 
3795   // Collect reclaim candidate information and register candidates with cset.
3796   RegisterHumongousWithInCSetFastTestClosure cl;
3797   heap_region_iterate(&cl);
3798 
3799   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3800   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3801                                                                   cl.total_humongous(),
3802                                                                   cl.candidate_humongous());
3803   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3804 
3805   // Finally flush all remembered set entries to re-check into the global DCQS.
3806   cl.flush_rem_set_entries();
3807 }
3808 
3809 void
3810 G1CollectedHeap::setup_surviving_young_words() {
3811   assert(_surviving_young_words == NULL, "pre-condition");
3812   uint array_length = g1_policy()->young_cset_region_length();
3813   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3814   if (_surviving_young_words == NULL) {
3815     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3816                           "Not enough space for young surv words summary.");
3817   }
3818   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3819 #ifdef ASSERT
3820   for (uint i = 0;  i < array_length; ++i) {
3821     assert( _surviving_young_words[i] == 0, "memset above" );
3822   }
3823 #endif // !ASSERT
3824 }
3825 
3826 void
3827 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3828   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3829   uint array_length = g1_policy()->young_cset_region_length();
3830   for (uint i = 0; i < array_length; ++i) {
3831     _surviving_young_words[i] += surv_young_words[i];
3832   }
3833 }
3834 
3835 void
3836 G1CollectedHeap::cleanup_surviving_young_words() {
3837   guarantee( _surviving_young_words != NULL, "pre-condition" );
3838   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3839   _surviving_young_words = NULL;
3840 }
3841 
3842 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3843   public:
3844     bool doHeapRegion(HeapRegion* hr) {
3845       if (!hr->continuesHumongous()) {
3846         hr->verify_rem_set();
3847       }
3848       return false;
3849     }
3850 };
3851 
3852 #ifdef ASSERT
3853 class VerifyCSetClosure: public HeapRegionClosure {
3854 public:
3855   bool doHeapRegion(HeapRegion* hr) {
3856     // Here we check that the CSet region's RSet is ready for parallel
3857     // iteration. The fields that we'll verify are only manipulated
3858     // when the region is part of a CSet and is collected. Afterwards,
3859     // we reset these fields when we clear the region's RSet (when the
3860     // region is freed) so they are ready when the region is
3861     // re-allocated. The only exception to this is if there's an
3862     // evacuation failure and instead of freeing the region we leave
3863     // it in the heap. In that case, we reset these fields during
3864     // evacuation failure handling.
3865     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3866 
3867     // Here's a good place to add any other checks we'd like to
3868     // perform on CSet regions.
3869     return false;
3870   }
3871 };
3872 #endif // ASSERT
3873 
3874 #if TASKQUEUE_STATS
3875 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3876   st->print_raw_cr("GC Task Stats");
3877   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3878   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3879 }
3880 
3881 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3882   print_taskqueue_stats_hdr(st);
3883 
3884   TaskQueueStats totals;
3885   const int n = workers() != NULL ? workers()->total_workers() : 1;
3886   for (int i = 0; i < n; ++i) {
3887     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3888     totals += task_queue(i)->stats;
3889   }
3890   st->print_raw("tot "); totals.print(st); st->cr();
3891 
3892   DEBUG_ONLY(totals.verify());
3893 }
3894 
3895 void G1CollectedHeap::reset_taskqueue_stats() {
3896   const int n = workers() != NULL ? workers()->total_workers() : 1;
3897   for (int i = 0; i < n; ++i) {
3898     task_queue(i)->stats.reset();
3899   }
3900 }
3901 #endif // TASKQUEUE_STATS
3902 
3903 void G1CollectedHeap::log_gc_header() {
3904   if (!G1Log::fine()) {
3905     return;
3906   }
3907 
3908   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3909 
3910   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3911     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3912     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3913 
3914   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3915 }
3916 
3917 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3918   if (!G1Log::fine()) {
3919     return;
3920   }
3921 
3922   if (G1Log::finer()) {
3923     if (evacuation_failed()) {
3924       gclog_or_tty->print(" (to-space exhausted)");
3925     }
3926     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3927     g1_policy()->phase_times()->note_gc_end();
3928     g1_policy()->phase_times()->print(pause_time_sec);
3929     g1_policy()->print_detailed_heap_transition();
3930   } else {
3931     if (evacuation_failed()) {
3932       gclog_or_tty->print("--");
3933     }
3934     g1_policy()->print_heap_transition();
3935     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3936   }
3937   gclog_or_tty->flush();
3938 }
3939 
3940 bool
3941 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3942   assert_at_safepoint(true /* should_be_vm_thread */);
3943   guarantee(!is_gc_active(), "collection is not reentrant");
3944 
3945   if (GC_locker::check_active_before_gc()) {
3946     return false;
3947   }
3948 
3949   _gc_timer_stw->register_gc_start();
3950 
3951   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3952 
3953   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3954   ResourceMark rm;
3955 
3956   print_heap_before_gc();
3957   trace_heap_before_gc(_gc_tracer_stw);
3958 
3959   verify_region_sets_optional();
3960   verify_dirty_young_regions();
3961 
3962   // This call will decide whether this pause is an initial-mark
3963   // pause. If it is, during_initial_mark_pause() will return true
3964   // for the duration of this pause.
3965   g1_policy()->decide_on_conc_mark_initiation();
3966 
3967   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3968   assert(!g1_policy()->during_initial_mark_pause() ||
3969           g1_policy()->gcs_are_young(), "sanity");
3970 
3971   // We also do not allow mixed GCs during marking.
3972   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3973 
3974   // Record whether this pause is an initial mark. When the current
3975   // thread has completed its logging output and it's safe to signal
3976   // the CM thread, the flag's value in the policy has been reset.
3977   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3978 
3979   // Inner scope for scope based logging, timers, and stats collection
3980   {
3981     EvacuationInfo evacuation_info;
3982 
3983     if (g1_policy()->during_initial_mark_pause()) {
3984       // We are about to start a marking cycle, so we increment the
3985       // full collection counter.
3986       increment_old_marking_cycles_started();
3987       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3988     }
3989 
3990     _gc_tracer_stw->report_yc_type(yc_type());
3991 
3992     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3993 
3994     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3995                                                                   workers()->active_workers(),
3996                                                                   Threads::number_of_non_daemon_threads());
3997     assert(UseDynamicNumberOfGCThreads ||
3998            active_workers == workers()->total_workers(),
3999            "If not dynamic should be using all the  workers");
4000     workers()->set_active_workers(active_workers);
4001 
4002 
4003     double pause_start_sec = os::elapsedTime();
4004     g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
4005     log_gc_header();
4006 
4007     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4008     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4009 
4010     // If the secondary_free_list is not empty, append it to the
4011     // free_list. No need to wait for the cleanup operation to finish;
4012     // the region allocation code will check the secondary_free_list
4013     // and wait if necessary. If the G1StressConcRegionFreeing flag is
4014     // set, skip this step so that the region allocation code has to
4015     // get entries from the secondary_free_list.
4016     if (!G1StressConcRegionFreeing) {
4017       append_secondary_free_list_if_not_empty_with_lock();
4018     }
4019 
4020     assert(check_young_list_well_formed(), "young list should be well formed");
4021     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
4022            "sanity check");
4023 
4024     // Don't dynamically change the number of GC threads this early.  A value of
4025     // 0 is used to indicate serial work.  When parallel work is done,
4026     // it will be set.
4027 
4028     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4029       IsGCActiveMark x;
4030 
4031       gc_prologue(false);
4032       increment_total_collections(false /* full gc */);
4033       increment_gc_time_stamp();
4034 
4035       if (VerifyRememberedSets) {
4036         if (!VerifySilently) {
4037           gclog_or_tty->print_cr("[Verifying RemSets before GC]");
4038         }
4039         VerifyRegionRemSetClosure v_cl;
4040         heap_region_iterate(&v_cl);
4041       }
4042 
4043       verify_before_gc();
4044       check_bitmaps("GC Start");
4045 
4046       COMPILER2_PRESENT(DerivedPointerTable::clear());
4047 
4048       // Please see comment in g1CollectedHeap.hpp and
4049       // G1CollectedHeap::ref_processing_init() to see how
4050       // reference processing currently works in G1.
4051 
4052       // Enable discovery in the STW reference processor
4053       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4054                                             true /*verify_no_refs*/);
4055 
4056       {
4057         // We want to temporarily turn off discovery by the
4058         // CM ref processor, if necessary, and turn it back on
4059         // on again later if we do. Using a scoped
4060         // NoRefDiscovery object will do this.
4061         NoRefDiscovery no_cm_discovery(ref_processor_cm());
4062 
4063         // Forget the current alloc region (we might even choose it to be part
4064         // of the collection set!).
4065         _allocator->release_mutator_alloc_region();
4066 
4067         // We should call this after we retire the mutator alloc
4068         // region(s) so that all the ALLOC / RETIRE events are generated
4069         // before the start GC event.
4070         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4071 
4072         // This timing is only used by the ergonomics to handle our pause target.
4073         // It is unclear why this should not include the full pause. We will
4074         // investigate this in CR 7178365.
4075         //
4076         // Preserving the old comment here if that helps the investigation:
4077         //
4078         // The elapsed time induced by the start time below deliberately elides
4079         // the possible verification above.
4080         double sample_start_time_sec = os::elapsedTime();
4081 
4082 #if YOUNG_LIST_VERBOSE
4083         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4084         _young_list->print();
4085         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4086 #endif // YOUNG_LIST_VERBOSE
4087 
4088         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4089 
4090         double scan_wait_start = os::elapsedTime();
4091         // We have to wait until the CM threads finish scanning the
4092         // root regions as it's the only way to ensure that all the
4093         // objects on them have been correctly scanned before we start
4094         // moving them during the GC.
4095         bool waited = _cm->root_regions()->wait_until_scan_finished();
4096         double wait_time_ms = 0.0;
4097         if (waited) {
4098           double scan_wait_end = os::elapsedTime();
4099           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4100         }
4101         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4102 
4103 #if YOUNG_LIST_VERBOSE
4104         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4105         _young_list->print();
4106 #endif // YOUNG_LIST_VERBOSE
4107 
4108         if (g1_policy()->during_initial_mark_pause()) {
4109           concurrent_mark()->checkpointRootsInitialPre();
4110         }
4111 
4112 #if YOUNG_LIST_VERBOSE
4113         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4114         _young_list->print();
4115         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4116 #endif // YOUNG_LIST_VERBOSE
4117 
4118         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4119 
4120         // Make sure the remembered sets are up to date. This needs to be
4121         // done before register_humongous_regions_with_cset(), because the
4122         // remembered sets are used there to choose eager reclaim candidates.
4123         // If the remembered sets are not up to date we might miss some
4124         // entries that need to be handled.
4125         g1_rem_set()->cleanupHRRS();
4126 
4127         register_humongous_regions_with_in_cset_fast_test();
4128 
4129         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4130 
4131         _cm->note_start_of_gc();
4132         // We call this after finalize_cset() to
4133         // ensure that the CSet has been finalized.
4134         _cm->verify_no_cset_oops();
4135 
4136         if (_hr_printer.is_active()) {
4137           HeapRegion* hr = g1_policy()->collection_set();
4138           while (hr != NULL) {
4139             _hr_printer.cset(hr);
4140             hr = hr->next_in_collection_set();
4141           }
4142         }
4143 
4144 #ifdef ASSERT
4145         VerifyCSetClosure cl;
4146         collection_set_iterate(&cl);
4147 #endif // ASSERT
4148 
4149         setup_surviving_young_words();
4150 
4151         // Initialize the GC alloc regions.
4152         _allocator->init_gc_alloc_regions(evacuation_info);
4153 
4154         // Actually do the work...
4155         evacuate_collection_set(evacuation_info);
4156 
4157         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4158 
4159         eagerly_reclaim_humongous_regions();
4160 
4161         g1_policy()->clear_collection_set();
4162 
4163         cleanup_surviving_young_words();
4164 
4165         // Start a new incremental collection set for the next pause.
4166         g1_policy()->start_incremental_cset_building();
4167 
4168         clear_cset_fast_test();
4169 
4170         _young_list->reset_sampled_info();
4171 
4172         // Don't check the whole heap at this point as the
4173         // GC alloc regions from this pause have been tagged
4174         // as survivors and moved on to the survivor list.
4175         // Survivor regions will fail the !is_young() check.
4176         assert(check_young_list_empty(false /* check_heap */),
4177           "young list should be empty");
4178 
4179 #if YOUNG_LIST_VERBOSE
4180         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4181         _young_list->print();
4182 #endif // YOUNG_LIST_VERBOSE
4183 
4184         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4185                                              _young_list->first_survivor_region(),
4186                                              _young_list->last_survivor_region());
4187 
4188         _young_list->reset_auxilary_lists();
4189 
4190         if (evacuation_failed()) {
4191           _allocator->set_used(recalculate_used());
4192           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4193           for (uint i = 0; i < n_queues; i++) {
4194             if (_evacuation_failed_info_array[i].has_failed()) {
4195               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4196             }
4197           }
4198         } else {
4199           // The "used" of the the collection set have already been subtracted
4200           // when they were freed.  Add in the bytes evacuated.
4201           _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4202         }
4203 
4204         if (g1_policy()->during_initial_mark_pause()) {
4205           // We have to do this before we notify the CM threads that
4206           // they can start working to make sure that all the
4207           // appropriate initialization is done on the CM object.
4208           concurrent_mark()->checkpointRootsInitialPost();
4209           set_marking_started();
4210           // Note that we don't actually trigger the CM thread at
4211           // this point. We do that later when we're sure that
4212           // the current thread has completed its logging output.
4213         }
4214 
4215         allocate_dummy_regions();
4216 
4217 #if YOUNG_LIST_VERBOSE
4218         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4219         _young_list->print();
4220         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4221 #endif // YOUNG_LIST_VERBOSE
4222 
4223         _allocator->init_mutator_alloc_region();
4224 
4225         {
4226           size_t expand_bytes = g1_policy()->expansion_amount();
4227           if (expand_bytes > 0) {
4228             size_t bytes_before = capacity();
4229             // No need for an ergo verbose message here,
4230             // expansion_amount() does this when it returns a value > 0.
4231             if (!expand(expand_bytes)) {
4232               // We failed to expand the heap. Cannot do anything about it.
4233             }
4234           }
4235         }
4236 
4237         // We redo the verification but now wrt to the new CSet which
4238         // has just got initialized after the previous CSet was freed.
4239         _cm->verify_no_cset_oops();
4240         _cm->note_end_of_gc();
4241 
4242         // This timing is only used by the ergonomics to handle our pause target.
4243         // It is unclear why this should not include the full pause. We will
4244         // investigate this in CR 7178365.
4245         double sample_end_time_sec = os::elapsedTime();
4246         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4247         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4248 
4249         MemoryService::track_memory_usage();
4250 
4251         // In prepare_for_verify() below we'll need to scan the deferred
4252         // update buffers to bring the RSets up-to-date if
4253         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4254         // the update buffers we'll probably need to scan cards on the
4255         // regions we just allocated to (i.e., the GC alloc
4256         // regions). However, during the last GC we called
4257         // set_saved_mark() on all the GC alloc regions, so card
4258         // scanning might skip the [saved_mark_word()...top()] area of
4259         // those regions (i.e., the area we allocated objects into
4260         // during the last GC). But it shouldn't. Given that
4261         // saved_mark_word() is conditional on whether the GC time stamp
4262         // on the region is current or not, by incrementing the GC time
4263         // stamp here we invalidate all the GC time stamps on all the
4264         // regions and saved_mark_word() will simply return top() for
4265         // all the regions. This is a nicer way of ensuring this rather
4266         // than iterating over the regions and fixing them. In fact, the
4267         // GC time stamp increment here also ensures that
4268         // saved_mark_word() will return top() between pauses, i.e.,
4269         // during concurrent refinement. So we don't need the
4270         // is_gc_active() check to decided which top to use when
4271         // scanning cards (see CR 7039627).
4272         increment_gc_time_stamp();
4273 
4274         if (VerifyRememberedSets) {
4275           if (!VerifySilently) {
4276             gclog_or_tty->print_cr("[Verifying RemSets after GC]");
4277           }
4278           VerifyRegionRemSetClosure v_cl;
4279           heap_region_iterate(&v_cl);
4280         }
4281 
4282         verify_after_gc();
4283         check_bitmaps("GC End");
4284 
4285         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4286         ref_processor_stw()->verify_no_references_recorded();
4287 
4288         // CM reference discovery will be re-enabled if necessary.
4289       }
4290 
4291       // We should do this after we potentially expand the heap so
4292       // that all the COMMIT events are generated before the end GC
4293       // event, and after we retire the GC alloc regions so that all
4294       // RETIRE events are generated before the end GC event.
4295       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4296 
4297 #ifdef TRACESPINNING
4298       ParallelTaskTerminator::print_termination_counts();
4299 #endif
4300 
4301       gc_epilogue(false);
4302     }
4303 
4304     // Print the remainder of the GC log output.
4305     log_gc_footer(os::elapsedTime() - pause_start_sec);
4306 
4307     // It is not yet to safe to tell the concurrent mark to
4308     // start as we have some optional output below. We don't want the
4309     // output from the concurrent mark thread interfering with this
4310     // logging output either.
4311 
4312     _hrm.verify_optional();
4313     verify_region_sets_optional();
4314 
4315     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4316     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4317 
4318     print_heap_after_gc();
4319     trace_heap_after_gc(_gc_tracer_stw);
4320 
4321     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4322     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4323     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4324     // before any GC notifications are raised.
4325     g1mm()->update_sizes();
4326 
4327     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4328     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4329     _gc_timer_stw->register_gc_end();
4330     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4331   }
4332   // It should now be safe to tell the concurrent mark thread to start
4333   // without its logging output interfering with the logging output
4334   // that came from the pause.
4335 
4336   if (should_start_conc_mark) {
4337     // CAUTION: after the doConcurrentMark() call below,
4338     // the concurrent marking thread(s) could be running
4339     // concurrently with us. Make sure that anything after
4340     // this point does not assume that we are the only GC thread
4341     // running. Note: of course, the actual marking work will
4342     // not start until the safepoint itself is released in
4343     // SuspendibleThreadSet::desynchronize().
4344     doConcurrentMark();
4345   }
4346 
4347   return true;
4348 }
4349 
4350 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4351   _drain_in_progress = false;
4352   set_evac_failure_closure(cl);
4353   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4354 }
4355 
4356 void G1CollectedHeap::finalize_for_evac_failure() {
4357   assert(_evac_failure_scan_stack != NULL &&
4358          _evac_failure_scan_stack->length() == 0,
4359          "Postcondition");
4360   assert(!_drain_in_progress, "Postcondition");
4361   delete _evac_failure_scan_stack;
4362   _evac_failure_scan_stack = NULL;
4363 }
4364 
4365 void G1CollectedHeap::remove_self_forwarding_pointers() {
4366   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4367 
4368   double remove_self_forwards_start = os::elapsedTime();
4369 
4370   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4371 
4372   if (G1CollectedHeap::use_parallel_gc_threads()) {
4373     set_par_threads();
4374     workers()->run_task(&rsfp_task);
4375     set_par_threads(0);
4376   } else {
4377     rsfp_task.work(0);
4378   }
4379 
4380   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4381 
4382   // Reset the claim values in the regions in the collection set.
4383   reset_cset_heap_region_claim_values();
4384 
4385   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4386 
4387   // Now restore saved marks, if any.
4388   assert(_objs_with_preserved_marks.size() ==
4389             _preserved_marks_of_objs.size(), "Both or none.");
4390   while (!_objs_with_preserved_marks.is_empty()) {
4391     oop obj = _objs_with_preserved_marks.pop();
4392     markOop m = _preserved_marks_of_objs.pop();
4393     obj->set_mark(m);
4394   }
4395   _objs_with_preserved_marks.clear(true);
4396   _preserved_marks_of_objs.clear(true);
4397 
4398   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4399 }
4400 
4401 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4402   _evac_failure_scan_stack->push(obj);
4403 }
4404 
4405 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4406   assert(_evac_failure_scan_stack != NULL, "precondition");
4407 
4408   while (_evac_failure_scan_stack->length() > 0) {
4409      oop obj = _evac_failure_scan_stack->pop();
4410      _evac_failure_closure->set_region(heap_region_containing(obj));
4411      obj->oop_iterate_backwards(_evac_failure_closure);
4412   }
4413 }
4414 
4415 oop
4416 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4417                                                oop old) {
4418   assert(obj_in_cs(old),
4419          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4420                  (HeapWord*) old));
4421   markOop m = old->mark();
4422   oop forward_ptr = old->forward_to_atomic(old);
4423   if (forward_ptr == NULL) {
4424     // Forward-to-self succeeded.
4425     assert(_par_scan_state != NULL, "par scan state");
4426     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4427     uint queue_num = _par_scan_state->queue_num();
4428 
4429     _evacuation_failed = true;
4430     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4431     if (_evac_failure_closure != cl) {
4432       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4433       assert(!_drain_in_progress,
4434              "Should only be true while someone holds the lock.");
4435       // Set the global evac-failure closure to the current thread's.
4436       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4437       set_evac_failure_closure(cl);
4438       // Now do the common part.
4439       handle_evacuation_failure_common(old, m);
4440       // Reset to NULL.
4441       set_evac_failure_closure(NULL);
4442     } else {
4443       // The lock is already held, and this is recursive.
4444       assert(_drain_in_progress, "This should only be the recursive case.");
4445       handle_evacuation_failure_common(old, m);
4446     }
4447     return old;
4448   } else {
4449     // Forward-to-self failed. Either someone else managed to allocate
4450     // space for this object (old != forward_ptr) or they beat us in
4451     // self-forwarding it (old == forward_ptr).
4452     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4453            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4454                    "should not be in the CSet",
4455                    (HeapWord*) old, (HeapWord*) forward_ptr));
4456     return forward_ptr;
4457   }
4458 }
4459 
4460 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4461   preserve_mark_if_necessary(old, m);
4462 
4463   HeapRegion* r = heap_region_containing(old);
4464   if (!r->evacuation_failed()) {
4465     r->set_evacuation_failed(true);
4466     _hr_printer.evac_failure(r);
4467   }
4468 
4469   push_on_evac_failure_scan_stack(old);
4470 
4471   if (!_drain_in_progress) {
4472     // prevent recursion in copy_to_survivor_space()
4473     _drain_in_progress = true;
4474     drain_evac_failure_scan_stack();
4475     _drain_in_progress = false;
4476   }
4477 }
4478 
4479 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4480   assert(evacuation_failed(), "Oversaving!");
4481   // We want to call the "for_promotion_failure" version only in the
4482   // case of a promotion failure.
4483   if (m->must_be_preserved_for_promotion_failure(obj)) {
4484     _objs_with_preserved_marks.push(obj);
4485     _preserved_marks_of_objs.push(m);
4486   }
4487 }
4488 
4489 void G1ParCopyHelper::mark_object(oop obj) {
4490   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4491 
4492   // We know that the object is not moving so it's safe to read its size.
4493   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4494 }
4495 
4496 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4497   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4498   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4499   assert(from_obj != to_obj, "should not be self-forwarded");
4500 
4501   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4502   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4503 
4504   // The object might be in the process of being copied by another
4505   // worker so we cannot trust that its to-space image is
4506   // well-formed. So we have to read its size from its from-space
4507   // image which we know should not be changing.
4508   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4509 }
4510 
4511 template <class T>
4512 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4513   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4514     _scanned_klass->record_modified_oops();
4515   }
4516 }
4517 
4518 template <G1Barrier barrier, G1Mark do_mark_object>
4519 template <class T>
4520 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4521   T heap_oop = oopDesc::load_heap_oop(p);
4522 
4523   if (oopDesc::is_null(heap_oop)) {
4524     return;
4525   }
4526 
4527   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4528 
4529   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4530 
4531   const InCSetState state = _g1->in_cset_state(obj);
4532   if (state.is_in_cset()) {
4533     oop forwardee;
4534     markOop m = obj->mark();
4535     if (m->is_marked()) {
4536       forwardee = (oop) m->decode_pointer();
4537     } else {
4538       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4539     }
4540     assert(forwardee != NULL, "forwardee should not be NULL");
4541     oopDesc::encode_store_heap_oop(p, forwardee);
4542     if (do_mark_object != G1MarkNone && forwardee != obj) {
4543       // If the object is self-forwarded we don't need to explicitly
4544       // mark it, the evacuation failure protocol will do so.
4545       mark_forwarded_object(obj, forwardee);
4546     }
4547 
4548     if (barrier == G1BarrierKlass) {
4549       do_klass_barrier(p, forwardee);
4550     }
4551   } else {
4552     if (state.is_humongous()) {
4553       _g1->set_humongous_is_live(obj);
4554     }
4555     // The object is not in collection set. If we're a root scanning
4556     // closure during an initial mark pause then attempt to mark the object.
4557     if (do_mark_object == G1MarkFromRoot) {
4558       mark_object(obj);
4559     }
4560   }
4561 
4562   if (barrier == G1BarrierEvac) {
4563     _par_scan_state->update_rs(_from, p, _worker_id);
4564   }
4565 }
4566 
4567 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4568 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4569 
4570 class G1ParEvacuateFollowersClosure : public VoidClosure {
4571 protected:
4572   G1CollectedHeap*              _g1h;
4573   G1ParScanThreadState*         _par_scan_state;
4574   RefToScanQueueSet*            _queues;
4575   ParallelTaskTerminator*       _terminator;
4576 
4577   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4578   RefToScanQueueSet*      queues()         { return _queues; }
4579   ParallelTaskTerminator* terminator()     { return _terminator; }
4580 
4581 public:
4582   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4583                                 G1ParScanThreadState* par_scan_state,
4584                                 RefToScanQueueSet* queues,
4585                                 ParallelTaskTerminator* terminator)
4586     : _g1h(g1h), _par_scan_state(par_scan_state),
4587       _queues(queues), _terminator(terminator) {}
4588 
4589   void do_void();
4590 
4591 private:
4592   inline bool offer_termination();
4593 };
4594 
4595 bool G1ParEvacuateFollowersClosure::offer_termination() {
4596   G1ParScanThreadState* const pss = par_scan_state();
4597   pss->start_term_time();
4598   const bool res = terminator()->offer_termination();
4599   pss->end_term_time();
4600   return res;
4601 }
4602 
4603 void G1ParEvacuateFollowersClosure::do_void() {
4604   G1ParScanThreadState* const pss = par_scan_state();
4605   pss->trim_queue();
4606   do {
4607     pss->steal_and_trim_queue(queues());
4608   } while (!offer_termination());
4609 }
4610 
4611 class G1KlassScanClosure : public KlassClosure {
4612  G1ParCopyHelper* _closure;
4613  bool             _process_only_dirty;
4614  int              _count;
4615  public:
4616   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4617       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4618   void do_klass(Klass* klass) {
4619     // If the klass has not been dirtied we know that there's
4620     // no references into  the young gen and we can skip it.
4621    if (!_process_only_dirty || klass->has_modified_oops()) {
4622       // Clean the klass since we're going to scavenge all the metadata.
4623       klass->clear_modified_oops();
4624 
4625       // Tell the closure that this klass is the Klass to scavenge
4626       // and is the one to dirty if oops are left pointing into the young gen.
4627       _closure->set_scanned_klass(klass);
4628 
4629       klass->oops_do(_closure);
4630 
4631       _closure->set_scanned_klass(NULL);
4632     }
4633     _count++;
4634   }
4635 };
4636 
4637 class G1ParTask : public AbstractGangTask {
4638 protected:
4639   G1CollectedHeap*       _g1h;
4640   RefToScanQueueSet      *_queues;
4641   G1RootProcessor*       _root_processor;
4642   ParallelTaskTerminator _terminator;
4643   uint _n_workers;
4644 
4645   Mutex _stats_lock;
4646   Mutex* stats_lock() { return &_stats_lock; }
4647 
4648 public:
4649   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4650     : AbstractGangTask("G1 collection"),
4651       _g1h(g1h),
4652       _queues(task_queues),
4653       _root_processor(root_processor),
4654       _terminator(0, _queues),
4655       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4656   {}
4657 
4658   RefToScanQueueSet* queues() { return _queues; }
4659 
4660   RefToScanQueue *work_queue(int i) {
4661     return queues()->queue(i);
4662   }
4663 
4664   ParallelTaskTerminator* terminator() { return &_terminator; }
4665 
4666   virtual void set_for_termination(int active_workers) {
4667     _root_processor->set_num_workers(active_workers);
4668     terminator()->reset_for_reuse(active_workers);
4669     _n_workers = active_workers;
4670   }
4671 
4672   // Helps out with CLD processing.
4673   //
4674   // During InitialMark we need to:
4675   // 1) Scavenge all CLDs for the young GC.
4676   // 2) Mark all objects directly reachable from strong CLDs.
4677   template <G1Mark do_mark_object>
4678   class G1CLDClosure : public CLDClosure {
4679     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4680     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4681     G1KlassScanClosure                                _klass_in_cld_closure;
4682     bool                                              _claim;
4683 
4684    public:
4685     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4686                  bool only_young, bool claim)
4687         : _oop_closure(oop_closure),
4688           _oop_in_klass_closure(oop_closure->g1(),
4689                                 oop_closure->pss(),
4690                                 oop_closure->rp()),
4691           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4692           _claim(claim) {
4693 
4694     }
4695 
4696     void do_cld(ClassLoaderData* cld) {
4697       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4698     }
4699   };
4700 
4701   void work(uint worker_id) {
4702     if (worker_id >= _n_workers) return;  // no work needed this round
4703 
4704     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4705 
4706     {
4707       ResourceMark rm;
4708       HandleMark   hm;
4709 
4710       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4711 
4712       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4713       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4714 
4715       pss.set_evac_failure_closure(&evac_failure_cl);
4716 
4717       bool only_young = _g1h->g1_policy()->gcs_are_young();
4718 
4719       // Non-IM young GC.
4720       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4721       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4722                                                                                only_young, // Only process dirty klasses.
4723                                                                                false);     // No need to claim CLDs.
4724       // IM young GC.
4725       //    Strong roots closures.
4726       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4727       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4728                                                                                false, // Process all klasses.
4729                                                                                true); // Need to claim CLDs.
4730       //    Weak roots closures.
4731       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4732       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4733                                                                                     false, // Process all klasses.
4734                                                                                     true); // Need to claim CLDs.
4735 
4736       OopClosure* strong_root_cl;
4737       OopClosure* weak_root_cl;
4738       CLDClosure* strong_cld_cl;
4739       CLDClosure* weak_cld_cl;
4740 
4741       bool trace_metadata = false;
4742 
4743       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4744         // We also need to mark copied objects.
4745         strong_root_cl = &scan_mark_root_cl;
4746         strong_cld_cl  = &scan_mark_cld_cl;
4747         if (ClassUnloadingWithConcurrentMark) {
4748           weak_root_cl = &scan_mark_weak_root_cl;
4749           weak_cld_cl  = &scan_mark_weak_cld_cl;
4750           trace_metadata = true;
4751         } else {
4752           weak_root_cl = &scan_mark_root_cl;
4753           weak_cld_cl  = &scan_mark_cld_cl;
4754         }
4755       } else {
4756         strong_root_cl = &scan_only_root_cl;
4757         weak_root_cl   = &scan_only_root_cl;
4758         strong_cld_cl  = &scan_only_cld_cl;
4759         weak_cld_cl    = &scan_only_cld_cl;
4760       }
4761 
4762       pss.start_strong_roots();
4763 
4764       _root_processor->evacuate_roots(strong_root_cl,
4765                                       weak_root_cl,
4766                                       strong_cld_cl,
4767                                       weak_cld_cl,
4768                                       trace_metadata,
4769                                       worker_id);
4770 
4771       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4772       _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4773                                             weak_root_cl,
4774                                             worker_id);
4775       pss.end_strong_roots();
4776 
4777       {
4778         double start = os::elapsedTime();
4779         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4780         evac.do_void();
4781         double elapsed_sec = os::elapsedTime() - start;
4782         double term_sec = pss.term_time();
4783         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4784         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4785         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4786       }
4787       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4788       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4789 
4790       if (ParallelGCVerbose) {
4791         MutexLocker x(stats_lock());
4792         pss.print_termination_stats(worker_id);
4793       }
4794 
4795       assert(pss.queue_is_empty(), "should be empty");
4796 
4797       // Close the inner scope so that the ResourceMark and HandleMark
4798       // destructors are executed here and are included as part of the
4799       // "GC Worker Time".
4800     }
4801     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4802   }
4803 };
4804 
4805 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4806 private:
4807   BoolObjectClosure* _is_alive;
4808   int _initial_string_table_size;
4809   int _initial_symbol_table_size;
4810 
4811   bool  _process_strings;
4812   int _strings_processed;
4813   int _strings_removed;
4814 
4815   bool  _process_symbols;
4816   int _symbols_processed;
4817   int _symbols_removed;
4818 
4819   bool _do_in_parallel;
4820 public:
4821   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4822     AbstractGangTask("String/Symbol Unlinking"),
4823     _is_alive(is_alive),
4824     _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4825     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4826     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4827 
4828     _initial_string_table_size = StringTable::the_table()->table_size();
4829     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4830     if (process_strings) {
4831       StringTable::clear_parallel_claimed_index();
4832     }
4833     if (process_symbols) {
4834       SymbolTable::clear_parallel_claimed_index();
4835     }
4836   }
4837 
4838   ~G1StringSymbolTableUnlinkTask() {
4839     guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4840               err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4841                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4842     guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4843               err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4844                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4845 
4846     if (G1TraceStringSymbolTableScrubbing) {
4847       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4848                              "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4849                              "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4850                              strings_processed(), strings_removed(),
4851                              symbols_processed(), symbols_removed());
4852     }
4853   }
4854 
4855   void work(uint worker_id) {
4856     if (_do_in_parallel) {
4857       int strings_processed = 0;
4858       int strings_removed = 0;
4859       int symbols_processed = 0;
4860       int symbols_removed = 0;
4861       if (_process_strings) {
4862         StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4863         Atomic::add(strings_processed, &_strings_processed);
4864         Atomic::add(strings_removed, &_strings_removed);
4865       }
4866       if (_process_symbols) {
4867         SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4868         Atomic::add(symbols_processed, &_symbols_processed);
4869         Atomic::add(symbols_removed, &_symbols_removed);
4870       }
4871     } else {
4872       if (_process_strings) {
4873         StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
4874       }
4875       if (_process_symbols) {
4876         SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
4877       }
4878     }
4879   }
4880 
4881   size_t strings_processed() const { return (size_t)_strings_processed; }
4882   size_t strings_removed()   const { return (size_t)_strings_removed; }
4883 
4884   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4885   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4886 };
4887 
4888 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4889 private:
4890   static Monitor* _lock;
4891 
4892   BoolObjectClosure* const _is_alive;
4893   const bool               _unloading_occurred;
4894   const uint               _num_workers;
4895 
4896   // Variables used to claim nmethods.
4897   nmethod* _first_nmethod;
4898   volatile nmethod* _claimed_nmethod;
4899 
4900   // The list of nmethods that need to be processed by the second pass.
4901   volatile nmethod* _postponed_list;
4902   volatile uint     _num_entered_barrier;
4903 
4904  public:
4905   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4906       _is_alive(is_alive),
4907       _unloading_occurred(unloading_occurred),
4908       _num_workers(num_workers),
4909       _first_nmethod(NULL),
4910       _claimed_nmethod(NULL),
4911       _postponed_list(NULL),
4912       _num_entered_barrier(0)
4913   {
4914     nmethod::increase_unloading_clock();
4915     _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
4916     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4917   }
4918 
4919   ~G1CodeCacheUnloadingTask() {
4920     CodeCache::verify_clean_inline_caches();
4921 
4922     CodeCache::set_needs_cache_clean(false);
4923     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4924 
4925     CodeCache::verify_icholder_relocations();
4926   }
4927 
4928  private:
4929   void add_to_postponed_list(nmethod* nm) {
4930       nmethod* old;
4931       do {
4932         old = (nmethod*)_postponed_list;
4933         nm->set_unloading_next(old);
4934       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4935   }
4936 
4937   void clean_nmethod(nmethod* nm) {
4938     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4939 
4940     if (postponed) {
4941       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4942       add_to_postponed_list(nm);
4943     }
4944 
4945     // Mark that this thread has been cleaned/unloaded.
4946     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4947     nm->set_unloading_clock(nmethod::global_unloading_clock());
4948   }
4949 
4950   void clean_nmethod_postponed(nmethod* nm) {
4951     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4952   }
4953 
4954   static const int MaxClaimNmethods = 16;
4955 
4956   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4957     nmethod* first;
4958     nmethod* last;
4959 
4960     do {
4961       *num_claimed_nmethods = 0;
4962 
4963       first = last = (nmethod*)_claimed_nmethod;
4964 
4965       if (first != NULL) {
4966         for (int i = 0; i < MaxClaimNmethods; i++) {
4967           last = CodeCache::alive_nmethod(CodeCache::next(last));
4968 
4969           if (last == NULL) {
4970             break;
4971           }
4972 
4973           claimed_nmethods[i] = last;
4974           (*num_claimed_nmethods)++;
4975         }
4976       }
4977 
4978     } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
4979   }
4980 
4981   nmethod* claim_postponed_nmethod() {
4982     nmethod* claim;
4983     nmethod* next;
4984 
4985     do {
4986       claim = (nmethod*)_postponed_list;
4987       if (claim == NULL) {
4988         return NULL;
4989       }
4990 
4991       next = claim->unloading_next();
4992 
4993     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4994 
4995     return claim;
4996   }
4997 
4998  public:
4999   // Mark that we're done with the first pass of nmethod cleaning.
5000   void barrier_mark(uint worker_id) {
5001     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5002     _num_entered_barrier++;
5003     if (_num_entered_barrier == _num_workers) {
5004       ml.notify_all();
5005     }
5006   }
5007 
5008   // See if we have to wait for the other workers to
5009   // finish their first-pass nmethod cleaning work.
5010   void barrier_wait(uint worker_id) {
5011     if (_num_entered_barrier < _num_workers) {
5012       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5013       while (_num_entered_barrier < _num_workers) {
5014           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5015       }
5016     }
5017   }
5018 
5019   // Cleaning and unloading of nmethods. Some work has to be postponed
5020   // to the second pass, when we know which nmethods survive.
5021   void work_first_pass(uint worker_id) {
5022     // The first nmethods is claimed by the first worker.
5023     if (worker_id == 0 && _first_nmethod != NULL) {
5024       clean_nmethod(_first_nmethod);
5025       _first_nmethod = NULL;
5026     }
5027 
5028     int num_claimed_nmethods;
5029     nmethod* claimed_nmethods[MaxClaimNmethods];
5030 
5031     while (true) {
5032       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5033 
5034       if (num_claimed_nmethods == 0) {
5035         break;
5036       }
5037 
5038       for (int i = 0; i < num_claimed_nmethods; i++) {
5039         clean_nmethod(claimed_nmethods[i]);
5040       }
5041     }
5042 
5043     // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
5044     // Need to retire the buffers now that this thread has stopped cleaning nmethods.
5045     MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
5046   }
5047 
5048   void work_second_pass(uint worker_id) {
5049     nmethod* nm;
5050     // Take care of postponed nmethods.
5051     while ((nm = claim_postponed_nmethod()) != NULL) {
5052       clean_nmethod_postponed(nm);
5053     }
5054   }
5055 };
5056 
5057 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5058 
5059 class G1KlassCleaningTask : public StackObj {
5060   BoolObjectClosure*                      _is_alive;
5061   volatile jint                           _clean_klass_tree_claimed;
5062   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5063 
5064  public:
5065   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5066       _is_alive(is_alive),
5067       _clean_klass_tree_claimed(0),
5068       _klass_iterator() {
5069   }
5070 
5071  private:
5072   bool claim_clean_klass_tree_task() {
5073     if (_clean_klass_tree_claimed) {
5074       return false;
5075     }
5076 
5077     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5078   }
5079 
5080   InstanceKlass* claim_next_klass() {
5081     Klass* klass;
5082     do {
5083       klass =_klass_iterator.next_klass();
5084     } while (klass != NULL && !klass->oop_is_instance());
5085 
5086     return (InstanceKlass*)klass;
5087   }
5088 
5089 public:
5090 
5091   void clean_klass(InstanceKlass* ik) {
5092     ik->clean_weak_instanceklass_links(_is_alive);
5093 
5094     if (JvmtiExport::has_redefined_a_class()) {
5095       InstanceKlass::purge_previous_versions(ik);
5096     }
5097   }
5098 
5099   void work() {
5100     ResourceMark rm;
5101 
5102     // One worker will clean the subklass/sibling klass tree.
5103     if (claim_clean_klass_tree_task()) {
5104       Klass::clean_subklass_tree(_is_alive);
5105     }
5106 
5107     // All workers will help cleaning the classes,
5108     InstanceKlass* klass;
5109     while ((klass = claim_next_klass()) != NULL) {
5110       clean_klass(klass);
5111     }
5112   }
5113 };
5114 
5115 // To minimize the remark pause times, the tasks below are done in parallel.
5116 class G1ParallelCleaningTask : public AbstractGangTask {
5117 private:
5118   G1StringSymbolTableUnlinkTask _string_symbol_task;
5119   G1CodeCacheUnloadingTask      _code_cache_task;
5120   G1KlassCleaningTask           _klass_cleaning_task;
5121 
5122 public:
5123   // The constructor is run in the VMThread.
5124   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5125       AbstractGangTask("Parallel Cleaning"),
5126       _string_symbol_task(is_alive, process_strings, process_symbols),
5127       _code_cache_task(num_workers, is_alive, unloading_occurred),
5128       _klass_cleaning_task(is_alive) {
5129   }
5130 
5131   void pre_work_verification() {
5132     // The VM Thread will have registered Metadata during the single-threaded phase of MetadataStackOnMark.
5133     assert(Thread::current()->is_VM_thread()
5134            || !MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5135   }
5136 
5137   void post_work_verification() {
5138     assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5139   }
5140 
5141   // The parallel work done by all worker threads.
5142   void work(uint worker_id) {
5143     pre_work_verification();
5144 
5145     // Do first pass of code cache cleaning.
5146     _code_cache_task.work_first_pass(worker_id);
5147 
5148     // Let the threads mark that the first pass is done.
5149     _code_cache_task.barrier_mark(worker_id);
5150 
5151     // Clean the Strings and Symbols.
5152     _string_symbol_task.work(worker_id);
5153 
5154     // Wait for all workers to finish the first code cache cleaning pass.
5155     _code_cache_task.barrier_wait(worker_id);
5156 
5157     // Do the second code cache cleaning work, which realize on
5158     // the liveness information gathered during the first pass.
5159     _code_cache_task.work_second_pass(worker_id);
5160 
5161     // Clean all klasses that were not unloaded.
5162     _klass_cleaning_task.work();
5163 
5164     post_work_verification();
5165   }
5166 };
5167 
5168 
5169 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5170                                         bool process_strings,
5171                                         bool process_symbols,
5172                                         bool class_unloading_occurred) {
5173   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5174                     workers()->active_workers() : 1);
5175 
5176   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5177                                         n_workers, class_unloading_occurred);
5178   if (G1CollectedHeap::use_parallel_gc_threads()) {
5179     set_par_threads(n_workers);
5180     workers()->run_task(&g1_unlink_task);
5181     set_par_threads(0);
5182   } else {
5183     g1_unlink_task.work(0);
5184   }
5185 }
5186 
5187 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5188                                                      bool process_strings, bool process_symbols) {
5189   {
5190     uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5191                      _g1h->workers()->active_workers() : 1);
5192     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5193     if (G1CollectedHeap::use_parallel_gc_threads()) {
5194       set_par_threads(n_workers);
5195       workers()->run_task(&g1_unlink_task);
5196       set_par_threads(0);
5197     } else {
5198       g1_unlink_task.work(0);
5199     }
5200   }
5201 
5202   if (G1StringDedup::is_enabled()) {
5203     G1StringDedup::unlink(is_alive);
5204   }
5205 }
5206 
5207 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5208  private:
5209   DirtyCardQueueSet* _queue;
5210  public:
5211   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5212 
5213   virtual void work(uint worker_id) {
5214     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5215     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5216 
5217     RedirtyLoggedCardTableEntryClosure cl;
5218     if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5219       _queue->par_apply_closure_to_all_completed_buffers(&cl);
5220     } else {
5221       _queue->apply_closure_to_all_completed_buffers(&cl);
5222     }
5223 
5224     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5225   }
5226 };
5227 
5228 void G1CollectedHeap::redirty_logged_cards() {
5229   double redirty_logged_cards_start = os::elapsedTime();
5230 
5231   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5232                    _g1h->workers()->active_workers() : 1);
5233 
5234   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5235   dirty_card_queue_set().reset_for_par_iteration();
5236   if (use_parallel_gc_threads()) {
5237     set_par_threads(n_workers);
5238     workers()->run_task(&redirty_task);
5239     set_par_threads(0);
5240   } else {
5241     redirty_task.work(0);
5242   }
5243 
5244   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5245   dcq.merge_bufferlists(&dirty_card_queue_set());
5246   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5247 
5248   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5249 }
5250 
5251 // Weak Reference Processing support
5252 
5253 // An always "is_alive" closure that is used to preserve referents.
5254 // If the object is non-null then it's alive.  Used in the preservation
5255 // of referent objects that are pointed to by reference objects
5256 // discovered by the CM ref processor.
5257 class G1AlwaysAliveClosure: public BoolObjectClosure {
5258   G1CollectedHeap* _g1;
5259 public:
5260   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5261   bool do_object_b(oop p) {
5262     if (p != NULL) {
5263       return true;
5264     }
5265     return false;
5266   }
5267 };
5268 
5269 bool G1STWIsAliveClosure::do_object_b(oop p) {
5270   // An object is reachable if it is outside the collection set,
5271   // or is inside and copied.
5272   return !_g1->obj_in_cs(p) || p->is_forwarded();
5273 }
5274 
5275 // Non Copying Keep Alive closure
5276 class G1KeepAliveClosure: public OopClosure {
5277   G1CollectedHeap* _g1;
5278 public:
5279   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5280   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5281   void do_oop(oop* p) {
5282     oop obj = *p;
5283     assert(obj != NULL, "the caller should have filtered out NULL values");
5284 
5285     const InCSetState cset_state = _g1->in_cset_state(obj);
5286     if (!cset_state.is_in_cset_or_humongous()) {
5287       return;
5288     }
5289     if (cset_state.is_in_cset()) {
5290       assert( obj->is_forwarded(), "invariant" );
5291       *p = obj->forwardee();
5292     } else {
5293       assert(!obj->is_forwarded(), "invariant" );
5294       assert(cset_state.is_humongous(),
5295              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5296       _g1->set_humongous_is_live(obj);
5297     }
5298   }
5299 };
5300 
5301 // Copying Keep Alive closure - can be called from both
5302 // serial and parallel code as long as different worker
5303 // threads utilize different G1ParScanThreadState instances
5304 // and different queues.
5305 
5306 class G1CopyingKeepAliveClosure: public OopClosure {
5307   G1CollectedHeap*         _g1h;
5308   OopClosure*              _copy_non_heap_obj_cl;
5309   G1ParScanThreadState*    _par_scan_state;
5310 
5311 public:
5312   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5313                             OopClosure* non_heap_obj_cl,
5314                             G1ParScanThreadState* pss):
5315     _g1h(g1h),
5316     _copy_non_heap_obj_cl(non_heap_obj_cl),
5317     _par_scan_state(pss)
5318   {}
5319 
5320   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5321   virtual void do_oop(      oop* p) { do_oop_work(p); }
5322 
5323   template <class T> void do_oop_work(T* p) {
5324     oop obj = oopDesc::load_decode_heap_oop(p);
5325 
5326     if (_g1h->is_in_cset_or_humongous(obj)) {
5327       // If the referent object has been forwarded (either copied
5328       // to a new location or to itself in the event of an
5329       // evacuation failure) then we need to update the reference
5330       // field and, if both reference and referent are in the G1
5331       // heap, update the RSet for the referent.
5332       //
5333       // If the referent has not been forwarded then we have to keep
5334       // it alive by policy. Therefore we have copy the referent.
5335       //
5336       // If the reference field is in the G1 heap then we can push
5337       // on the PSS queue. When the queue is drained (after each
5338       // phase of reference processing) the object and it's followers
5339       // will be copied, the reference field set to point to the
5340       // new location, and the RSet updated. Otherwise we need to
5341       // use the the non-heap or metadata closures directly to copy
5342       // the referent object and update the pointer, while avoiding
5343       // updating the RSet.
5344 
5345       if (_g1h->is_in_g1_reserved(p)) {
5346         _par_scan_state->push_on_queue(p);
5347       } else {
5348         assert(!Metaspace::contains((const void*)p),
5349                err_msg("Unexpectedly found a pointer from metadata: "
5350                               PTR_FORMAT, p));
5351         _copy_non_heap_obj_cl->do_oop(p);
5352       }
5353     }
5354   }
5355 };
5356 
5357 // Serial drain queue closure. Called as the 'complete_gc'
5358 // closure for each discovered list in some of the
5359 // reference processing phases.
5360 
5361 class G1STWDrainQueueClosure: public VoidClosure {
5362 protected:
5363   G1CollectedHeap* _g1h;
5364   G1ParScanThreadState* _par_scan_state;
5365 
5366   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5367 
5368 public:
5369   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5370     _g1h(g1h),
5371     _par_scan_state(pss)
5372   { }
5373 
5374   void do_void() {
5375     G1ParScanThreadState* const pss = par_scan_state();
5376     pss->trim_queue();
5377   }
5378 };
5379 
5380 // Parallel Reference Processing closures
5381 
5382 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5383 // processing during G1 evacuation pauses.
5384 
5385 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5386 private:
5387   G1CollectedHeap*   _g1h;
5388   RefToScanQueueSet* _queues;
5389   FlexibleWorkGang*  _workers;
5390   int                _active_workers;
5391 
5392 public:
5393   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5394                         FlexibleWorkGang* workers,
5395                         RefToScanQueueSet *task_queues,
5396                         int n_workers) :
5397     _g1h(g1h),
5398     _queues(task_queues),
5399     _workers(workers),
5400     _active_workers(n_workers)
5401   {
5402     assert(n_workers > 0, "shouldn't call this otherwise");
5403   }
5404 
5405   // Executes the given task using concurrent marking worker threads.
5406   virtual void execute(ProcessTask& task);
5407   virtual void execute(EnqueueTask& task);
5408 };
5409 
5410 // Gang task for possibly parallel reference processing
5411 
5412 class G1STWRefProcTaskProxy: public AbstractGangTask {
5413   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5414   ProcessTask&     _proc_task;
5415   G1CollectedHeap* _g1h;
5416   RefToScanQueueSet *_task_queues;
5417   ParallelTaskTerminator* _terminator;
5418 
5419 public:
5420   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5421                      G1CollectedHeap* g1h,
5422                      RefToScanQueueSet *task_queues,
5423                      ParallelTaskTerminator* terminator) :
5424     AbstractGangTask("Process reference objects in parallel"),
5425     _proc_task(proc_task),
5426     _g1h(g1h),
5427     _task_queues(task_queues),
5428     _terminator(terminator)
5429   {}
5430 
5431   virtual void work(uint worker_id) {
5432     // The reference processing task executed by a single worker.
5433     ResourceMark rm;
5434     HandleMark   hm;
5435 
5436     G1STWIsAliveClosure is_alive(_g1h);
5437 
5438     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5439     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5440 
5441     pss.set_evac_failure_closure(&evac_failure_cl);
5442 
5443     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5444 
5445     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5446 
5447     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5448 
5449     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5450       // We also need to mark copied objects.
5451       copy_non_heap_cl = &copy_mark_non_heap_cl;
5452     }
5453 
5454     // Keep alive closure.
5455     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5456 
5457     // Complete GC closure
5458     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5459 
5460     // Call the reference processing task's work routine.
5461     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5462 
5463     // Note we cannot assert that the refs array is empty here as not all
5464     // of the processing tasks (specifically phase2 - pp2_work) execute
5465     // the complete_gc closure (which ordinarily would drain the queue) so
5466     // the queue may not be empty.
5467   }
5468 };
5469 
5470 // Driver routine for parallel reference processing.
5471 // Creates an instance of the ref processing gang
5472 // task and has the worker threads execute it.
5473 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5474   assert(_workers != NULL, "Need parallel worker threads.");
5475 
5476   ParallelTaskTerminator terminator(_active_workers, _queues);
5477   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5478 
5479   _g1h->set_par_threads(_active_workers);
5480   _workers->run_task(&proc_task_proxy);
5481   _g1h->set_par_threads(0);
5482 }
5483 
5484 // Gang task for parallel reference enqueueing.
5485 
5486 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5487   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5488   EnqueueTask& _enq_task;
5489 
5490 public:
5491   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5492     AbstractGangTask("Enqueue reference objects in parallel"),
5493     _enq_task(enq_task)
5494   { }
5495 
5496   virtual void work(uint worker_id) {
5497     _enq_task.work(worker_id);
5498   }
5499 };
5500 
5501 // Driver routine for parallel reference enqueueing.
5502 // Creates an instance of the ref enqueueing gang
5503 // task and has the worker threads execute it.
5504 
5505 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5506   assert(_workers != NULL, "Need parallel worker threads.");
5507 
5508   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5509 
5510   _g1h->set_par_threads(_active_workers);
5511   _workers->run_task(&enq_task_proxy);
5512   _g1h->set_par_threads(0);
5513 }
5514 
5515 // End of weak reference support closures
5516 
5517 // Abstract task used to preserve (i.e. copy) any referent objects
5518 // that are in the collection set and are pointed to by reference
5519 // objects discovered by the CM ref processor.
5520 
5521 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5522 protected:
5523   G1CollectedHeap* _g1h;
5524   RefToScanQueueSet      *_queues;
5525   ParallelTaskTerminator _terminator;
5526   uint _n_workers;
5527 
5528 public:
5529   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5530     AbstractGangTask("ParPreserveCMReferents"),
5531     _g1h(g1h),
5532     _queues(task_queues),
5533     _terminator(workers, _queues),
5534     _n_workers(workers)
5535   { }
5536 
5537   void work(uint worker_id) {
5538     ResourceMark rm;
5539     HandleMark   hm;
5540 
5541     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5542     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5543 
5544     pss.set_evac_failure_closure(&evac_failure_cl);
5545 
5546     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5547 
5548     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5549 
5550     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5551 
5552     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5553 
5554     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5555       // We also need to mark copied objects.
5556       copy_non_heap_cl = &copy_mark_non_heap_cl;
5557     }
5558 
5559     // Is alive closure
5560     G1AlwaysAliveClosure always_alive(_g1h);
5561 
5562     // Copying keep alive closure. Applied to referent objects that need
5563     // to be copied.
5564     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5565 
5566     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5567 
5568     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5569     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5570 
5571     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5572     // So this must be true - but assert just in case someone decides to
5573     // change the worker ids.
5574     assert(0 <= worker_id && worker_id < limit, "sanity");
5575     assert(!rp->discovery_is_atomic(), "check this code");
5576 
5577     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5578     for (uint idx = worker_id; idx < limit; idx += stride) {
5579       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5580 
5581       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5582       while (iter.has_next()) {
5583         // Since discovery is not atomic for the CM ref processor, we
5584         // can see some null referent objects.
5585         iter.load_ptrs(DEBUG_ONLY(true));
5586         oop ref = iter.obj();
5587 
5588         // This will filter nulls.
5589         if (iter.is_referent_alive()) {
5590           iter.make_referent_alive();
5591         }
5592         iter.move_to_next();
5593       }
5594     }
5595 
5596     // Drain the queue - which may cause stealing
5597     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5598     drain_queue.do_void();
5599     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5600     assert(pss.queue_is_empty(), "should be");
5601   }
5602 };
5603 
5604 // Weak Reference processing during an evacuation pause (part 1).
5605 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5606   double ref_proc_start = os::elapsedTime();
5607 
5608   ReferenceProcessor* rp = _ref_processor_stw;
5609   assert(rp->discovery_enabled(), "should have been enabled");
5610 
5611   // Any reference objects, in the collection set, that were 'discovered'
5612   // by the CM ref processor should have already been copied (either by
5613   // applying the external root copy closure to the discovered lists, or
5614   // by following an RSet entry).
5615   //
5616   // But some of the referents, that are in the collection set, that these
5617   // reference objects point to may not have been copied: the STW ref
5618   // processor would have seen that the reference object had already
5619   // been 'discovered' and would have skipped discovering the reference,
5620   // but would not have treated the reference object as a regular oop.
5621   // As a result the copy closure would not have been applied to the
5622   // referent object.
5623   //
5624   // We need to explicitly copy these referent objects - the references
5625   // will be processed at the end of remarking.
5626   //
5627   // We also need to do this copying before we process the reference
5628   // objects discovered by the STW ref processor in case one of these
5629   // referents points to another object which is also referenced by an
5630   // object discovered by the STW ref processor.
5631 
5632   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5633            no_of_gc_workers == workers()->active_workers(),
5634            "Need to reset active GC workers");
5635 
5636   set_par_threads(no_of_gc_workers);
5637   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5638                                                  no_of_gc_workers,
5639                                                  _task_queues);
5640 
5641   if (G1CollectedHeap::use_parallel_gc_threads()) {
5642     workers()->run_task(&keep_cm_referents);
5643   } else {
5644     keep_cm_referents.work(0);
5645   }
5646 
5647   set_par_threads(0);
5648 
5649   // Closure to test whether a referent is alive.
5650   G1STWIsAliveClosure is_alive(this);
5651 
5652   // Even when parallel reference processing is enabled, the processing
5653   // of JNI refs is serial and performed serially by the current thread
5654   // rather than by a worker. The following PSS will be used for processing
5655   // JNI refs.
5656 
5657   // Use only a single queue for this PSS.
5658   G1ParScanThreadState            pss(this, 0, NULL);
5659 
5660   // We do not embed a reference processor in the copying/scanning
5661   // closures while we're actually processing the discovered
5662   // reference objects.
5663   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5664 
5665   pss.set_evac_failure_closure(&evac_failure_cl);
5666 
5667   assert(pss.queue_is_empty(), "pre-condition");
5668 
5669   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5670 
5671   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5672 
5673   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5674 
5675   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5676     // We also need to mark copied objects.
5677     copy_non_heap_cl = &copy_mark_non_heap_cl;
5678   }
5679 
5680   // Keep alive closure.
5681   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5682 
5683   // Serial Complete GC closure
5684   G1STWDrainQueueClosure drain_queue(this, &pss);
5685 
5686   // Setup the soft refs policy...
5687   rp->setup_policy(false);
5688 
5689   ReferenceProcessorStats stats;
5690   if (!rp->processing_is_mt()) {
5691     // Serial reference processing...
5692     stats = rp->process_discovered_references(&is_alive,
5693                                               &keep_alive,
5694                                               &drain_queue,
5695                                               NULL,
5696                                               _gc_timer_stw,
5697                                               _gc_tracer_stw->gc_id());
5698   } else {
5699     // Parallel reference processing
5700     assert(rp->num_q() == no_of_gc_workers, "sanity");
5701     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5702 
5703     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5704     stats = rp->process_discovered_references(&is_alive,
5705                                               &keep_alive,
5706                                               &drain_queue,
5707                                               &par_task_executor,
5708                                               _gc_timer_stw,
5709                                               _gc_tracer_stw->gc_id());
5710   }
5711 
5712   _gc_tracer_stw->report_gc_reference_stats(stats);
5713 
5714   // We have completed copying any necessary live referent objects.
5715   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5716 
5717   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5718   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5719 }
5720 
5721 // Weak Reference processing during an evacuation pause (part 2).
5722 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5723   double ref_enq_start = os::elapsedTime();
5724 
5725   ReferenceProcessor* rp = _ref_processor_stw;
5726   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5727 
5728   // Now enqueue any remaining on the discovered lists on to
5729   // the pending list.
5730   if (!rp->processing_is_mt()) {
5731     // Serial reference processing...
5732     rp->enqueue_discovered_references();
5733   } else {
5734     // Parallel reference enqueueing
5735 
5736     assert(no_of_gc_workers == workers()->active_workers(),
5737            "Need to reset active workers");
5738     assert(rp->num_q() == no_of_gc_workers, "sanity");
5739     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5740 
5741     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5742     rp->enqueue_discovered_references(&par_task_executor);
5743   }
5744 
5745   rp->verify_no_references_recorded();
5746   assert(!rp->discovery_enabled(), "should have been disabled");
5747 
5748   // FIXME
5749   // CM's reference processing also cleans up the string and symbol tables.
5750   // Should we do that here also? We could, but it is a serial operation
5751   // and could significantly increase the pause time.
5752 
5753   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5754   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5755 }
5756 
5757 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5758   _expand_heap_after_alloc_failure = true;
5759   _evacuation_failed = false;
5760 
5761   // Should G1EvacuationFailureALot be in effect for this GC?
5762   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5763 
5764   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5765 
5766   // Disable the hot card cache.
5767   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5768   hot_card_cache->reset_hot_cache_claimed_index();
5769   hot_card_cache->set_use_cache(false);
5770 
5771   const uint n_workers = workers()->active_workers();
5772   assert(UseDynamicNumberOfGCThreads ||
5773          n_workers == workers()->total_workers(),
5774          "If not dynamic should be using all the  workers");
5775   set_par_threads(n_workers);
5776 
5777   init_for_evac_failure(NULL);
5778 
5779   rem_set()->prepare_for_younger_refs_iterate(true);
5780 
5781   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5782   double start_par_time_sec = os::elapsedTime();
5783   double end_par_time_sec;
5784 
5785   {
5786     G1RootProcessor root_processor(this);
5787     G1ParTask g1_par_task(this, _task_queues, &root_processor);
5788     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5789     if (g1_policy()->during_initial_mark_pause()) {
5790       ClassLoaderDataGraph::clear_claimed_marks();
5791     }
5792 
5793     if (G1CollectedHeap::use_parallel_gc_threads()) {
5794       // The individual threads will set their evac-failure closures.
5795       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5796       // These tasks use ShareHeap::_process_strong_tasks
5797       assert(UseDynamicNumberOfGCThreads ||
5798              workers()->active_workers() == workers()->total_workers(),
5799              "If not dynamic should be using all the  workers");
5800       workers()->run_task(&g1_par_task);
5801     } else {
5802       g1_par_task.set_for_termination(n_workers);
5803       g1_par_task.work(0);
5804     }
5805     end_par_time_sec = os::elapsedTime();
5806 
5807     // Closing the inner scope will execute the destructor
5808     // for the G1RootProcessor object. We record the current
5809     // elapsed time before closing the scope so that time
5810     // taken for the destructor is NOT included in the
5811     // reported parallel time.
5812   }
5813 
5814   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5815 
5816   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5817   phase_times->record_par_time(par_time_ms);
5818 
5819   double code_root_fixup_time_ms =
5820         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5821   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5822 
5823   set_par_threads(0);
5824 
5825   // Process any discovered reference objects - we have
5826   // to do this _before_ we retire the GC alloc regions
5827   // as we may have to copy some 'reachable' referent
5828   // objects (and their reachable sub-graphs) that were
5829   // not copied during the pause.
5830   process_discovered_references(n_workers);
5831 
5832   if (G1StringDedup::is_enabled()) {
5833     double fixup_start = os::elapsedTime();
5834 
5835     G1STWIsAliveClosure is_alive(this);
5836     G1KeepAliveClosure keep_alive(this);
5837     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5838 
5839     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5840     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5841   }
5842 
5843   _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5844   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5845 
5846   // Reset and re-enable the hot card cache.
5847   // Note the counts for the cards in the regions in the
5848   // collection set are reset when the collection set is freed.
5849   hot_card_cache->reset_hot_cache();
5850   hot_card_cache->set_use_cache(true);
5851 
5852   purge_code_root_memory();
5853 
5854   if (g1_policy()->during_initial_mark_pause()) {
5855     // Reset the claim values set during marking the strong code roots
5856     reset_heap_region_claim_values();
5857   }
5858 
5859   finalize_for_evac_failure();
5860 
5861   if (evacuation_failed()) {
5862     remove_self_forwarding_pointers();
5863 
5864     // Reset the G1EvacuationFailureALot counters and flags
5865     // Note: the values are reset only when an actual
5866     // evacuation failure occurs.
5867     NOT_PRODUCT(reset_evacuation_should_fail();)
5868   }
5869 
5870   // Enqueue any remaining references remaining on the STW
5871   // reference processor's discovered lists. We need to do
5872   // this after the card table is cleaned (and verified) as
5873   // the act of enqueueing entries on to the pending list
5874   // will log these updates (and dirty their associated
5875   // cards). We need these updates logged to update any
5876   // RSets.
5877   enqueue_discovered_references(n_workers);
5878 
5879   redirty_logged_cards();
5880   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5881 }
5882 
5883 void G1CollectedHeap::free_region(HeapRegion* hr,
5884                                   FreeRegionList* free_list,
5885                                   bool par,
5886                                   bool locked) {
5887   assert(!hr->is_free(), "the region should not be free");
5888   assert(!hr->is_empty(), "the region should not be empty");
5889   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5890   assert(free_list != NULL, "pre-condition");
5891 
5892   if (G1VerifyBitmaps) {
5893     MemRegion mr(hr->bottom(), hr->end());
5894     concurrent_mark()->clearRangePrevBitmap(mr);
5895   }
5896 
5897   // Clear the card counts for this region.
5898   // Note: we only need to do this if the region is not young
5899   // (since we don't refine cards in young regions).
5900   if (!hr->is_young()) {
5901     _cg1r->hot_card_cache()->reset_card_counts(hr);
5902   }
5903   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5904   free_list->add_ordered(hr);
5905 }
5906 
5907 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5908                                      FreeRegionList* free_list,
5909                                      bool par) {
5910   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5911   assert(free_list != NULL, "pre-condition");
5912 
5913   size_t hr_capacity = hr->capacity();
5914   // We need to read this before we make the region non-humongous,
5915   // otherwise the information will be gone.
5916   uint last_index = hr->last_hc_index();
5917   hr->clear_humongous();
5918   free_region(hr, free_list, par);
5919 
5920   uint i = hr->hrm_index() + 1;
5921   while (i < last_index) {
5922     HeapRegion* curr_hr = region_at(i);
5923     assert(curr_hr->continuesHumongous(), "invariant");
5924     curr_hr->clear_humongous();
5925     free_region(curr_hr, free_list, par);
5926     i += 1;
5927   }
5928 }
5929 
5930 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5931                                        const HeapRegionSetCount& humongous_regions_removed) {
5932   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5933     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5934     _old_set.bulk_remove(old_regions_removed);
5935     _humongous_set.bulk_remove(humongous_regions_removed);
5936   }
5937 
5938 }
5939 
5940 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5941   assert(list != NULL, "list can't be null");
5942   if (!list->is_empty()) {
5943     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5944     _hrm.insert_list_into_free_list(list);
5945   }
5946 }
5947 
5948 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5949   _allocator->decrease_used(bytes);
5950 }
5951 
5952 class G1ParCleanupCTTask : public AbstractGangTask {
5953   G1SATBCardTableModRefBS* _ct_bs;
5954   G1CollectedHeap* _g1h;
5955   HeapRegion* volatile _su_head;
5956 public:
5957   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5958                      G1CollectedHeap* g1h) :
5959     AbstractGangTask("G1 Par Cleanup CT Task"),
5960     _ct_bs(ct_bs), _g1h(g1h) { }
5961 
5962   void work(uint worker_id) {
5963     HeapRegion* r;
5964     while (r = _g1h->pop_dirty_cards_region()) {
5965       clear_cards(r);
5966     }
5967   }
5968 
5969   void clear_cards(HeapRegion* r) {
5970     // Cards of the survivors should have already been dirtied.
5971     if (!r->is_survivor()) {
5972       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5973     }
5974   }
5975 };
5976 
5977 #ifndef PRODUCT
5978 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5979   G1CollectedHeap* _g1h;
5980   G1SATBCardTableModRefBS* _ct_bs;
5981 public:
5982   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5983     : _g1h(g1h), _ct_bs(ct_bs) { }
5984   virtual bool doHeapRegion(HeapRegion* r) {
5985     if (r->is_survivor()) {
5986       _g1h->verify_dirty_region(r);
5987     } else {
5988       _g1h->verify_not_dirty_region(r);
5989     }
5990     return false;
5991   }
5992 };
5993 
5994 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5995   // All of the region should be clean.
5996   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5997   MemRegion mr(hr->bottom(), hr->end());
5998   ct_bs->verify_not_dirty_region(mr);
5999 }
6000 
6001 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6002   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
6003   // dirty allocated blocks as they allocate them. The thread that
6004   // retires each region and replaces it with a new one will do a
6005   // maximal allocation to fill in [pre_dummy_top(),end()] but will
6006   // not dirty that area (one less thing to have to do while holding
6007   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6008   // is dirty.
6009   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6010   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6011   if (hr->is_young()) {
6012     ct_bs->verify_g1_young_region(mr);
6013   } else {
6014     ct_bs->verify_dirty_region(mr);
6015   }
6016 }
6017 
6018 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6019   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6020   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6021     verify_dirty_region(hr);
6022   }
6023 }
6024 
6025 void G1CollectedHeap::verify_dirty_young_regions() {
6026   verify_dirty_young_list(_young_list->first_region());
6027 }
6028 
6029 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6030                                                HeapWord* tams, HeapWord* end) {
6031   guarantee(tams <= end,
6032             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6033   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6034   if (result < end) {
6035     gclog_or_tty->cr();
6036     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6037                            bitmap_name, result);
6038     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6039                            bitmap_name, tams, end);
6040     return false;
6041   }
6042   return true;
6043 }
6044 
6045 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6046   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6047   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6048 
6049   HeapWord* bottom = hr->bottom();
6050   HeapWord* ptams  = hr->prev_top_at_mark_start();
6051   HeapWord* ntams  = hr->next_top_at_mark_start();
6052   HeapWord* end    = hr->end();
6053 
6054   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6055 
6056   bool res_n = true;
6057   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6058   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6059   // if we happen to be in that state.
6060   if (mark_in_progress() || !_cmThread->in_progress()) {
6061     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6062   }
6063   if (!res_p || !res_n) {
6064     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6065                            HR_FORMAT_PARAMS(hr));
6066     gclog_or_tty->print_cr("#### Caller: %s", caller);
6067     return false;
6068   }
6069   return true;
6070 }
6071 
6072 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6073   if (!G1VerifyBitmaps) return;
6074 
6075   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6076 }
6077 
6078 class G1VerifyBitmapClosure : public HeapRegionClosure {
6079 private:
6080   const char* _caller;
6081   G1CollectedHeap* _g1h;
6082   bool _failures;
6083 
6084 public:
6085   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6086     _caller(caller), _g1h(g1h), _failures(false) { }
6087 
6088   bool failures() { return _failures; }
6089 
6090   virtual bool doHeapRegion(HeapRegion* hr) {
6091     if (hr->continuesHumongous()) return false;
6092 
6093     bool result = _g1h->verify_bitmaps(_caller, hr);
6094     if (!result) {
6095       _failures = true;
6096     }
6097     return false;
6098   }
6099 };
6100 
6101 void G1CollectedHeap::check_bitmaps(const char* caller) {
6102   if (!G1VerifyBitmaps) return;
6103 
6104   G1VerifyBitmapClosure cl(caller, this);
6105   heap_region_iterate(&cl);
6106   guarantee(!cl.failures(), "bitmap verification");
6107 }
6108 
6109 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
6110  private:
6111   bool _failures;
6112  public:
6113   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
6114 
6115   virtual bool doHeapRegion(HeapRegion* hr) {
6116     uint i = hr->hrm_index();
6117     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
6118     if (hr->isHumongous()) {
6119       if (hr->in_collection_set()) {
6120         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
6121         _failures = true;
6122         return true;
6123       }
6124       if (cset_state.is_in_cset()) {
6125         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
6126         _failures = true;
6127         return true;
6128       }
6129       if (hr->continuesHumongous() && cset_state.is_humongous()) {
6130         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
6131         _failures = true;
6132         return true;
6133       }
6134     } else {
6135       if (cset_state.is_humongous()) {
6136         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
6137         _failures = true;
6138         return true;
6139       }
6140       if (hr->in_collection_set() != cset_state.is_in_cset()) {
6141         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6142                                hr->in_collection_set(), cset_state.value(), i);
6143        _failures = true;
6144        return true;
6145       }
6146       if (cset_state.is_in_cset()) {
6147         if (hr->is_young() != (cset_state.is_young())) {
6148           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6149                                  hr->is_young(), cset_state.value(), i);
6150           _failures = true;
6151           return true;
6152         }
6153         if (hr->is_old() != (cset_state.is_old())) {
6154           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6155                                  hr->is_old(), cset_state.value(), i);
6156           _failures = true;
6157           return true;
6158         }
6159       }
6160     }
6161     return false;
6162   }
6163 
6164   bool failures() const { return _failures; }
6165 };
6166 
6167 bool G1CollectedHeap::check_cset_fast_test() {
6168   G1CheckCSetFastTableClosure cl;
6169   _hrm.iterate(&cl);
6170   return !cl.failures();
6171 }
6172 #endif // PRODUCT
6173 
6174 void G1CollectedHeap::cleanUpCardTable() {
6175   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6176   double start = os::elapsedTime();
6177 
6178   {
6179     // Iterate over the dirty cards region list.
6180     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6181 
6182     if (G1CollectedHeap::use_parallel_gc_threads()) {
6183       set_par_threads();
6184       workers()->run_task(&cleanup_task);
6185       set_par_threads(0);
6186     } else {
6187       while (_dirty_cards_region_list) {
6188         HeapRegion* r = _dirty_cards_region_list;
6189         cleanup_task.clear_cards(r);
6190         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6191         if (_dirty_cards_region_list == r) {
6192           // The last region.
6193           _dirty_cards_region_list = NULL;
6194         }
6195         r->set_next_dirty_cards_region(NULL);
6196       }
6197     }
6198 #ifndef PRODUCT
6199     if (G1VerifyCTCleanup || VerifyAfterGC) {
6200       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6201       heap_region_iterate(&cleanup_verifier);
6202     }
6203 #endif
6204   }
6205 
6206   double elapsed = os::elapsedTime() - start;
6207   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6208 }
6209 
6210 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6211   size_t pre_used = 0;
6212   FreeRegionList local_free_list("Local List for CSet Freeing");
6213 
6214   double young_time_ms     = 0.0;
6215   double non_young_time_ms = 0.0;
6216 
6217   // Since the collection set is a superset of the the young list,
6218   // all we need to do to clear the young list is clear its
6219   // head and length, and unlink any young regions in the code below
6220   _young_list->clear();
6221 
6222   G1CollectorPolicy* policy = g1_policy();
6223 
6224   double start_sec = os::elapsedTime();
6225   bool non_young = true;
6226 
6227   HeapRegion* cur = cs_head;
6228   int age_bound = -1;
6229   size_t rs_lengths = 0;
6230 
6231   while (cur != NULL) {
6232     assert(!is_on_master_free_list(cur), "sanity");
6233     if (non_young) {
6234       if (cur->is_young()) {
6235         double end_sec = os::elapsedTime();
6236         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6237         non_young_time_ms += elapsed_ms;
6238 
6239         start_sec = os::elapsedTime();
6240         non_young = false;
6241       }
6242     } else {
6243       if (!cur->is_young()) {
6244         double end_sec = os::elapsedTime();
6245         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6246         young_time_ms += elapsed_ms;
6247 
6248         start_sec = os::elapsedTime();
6249         non_young = true;
6250       }
6251     }
6252 
6253     rs_lengths += cur->rem_set()->occupied_locked();
6254 
6255     HeapRegion* next = cur->next_in_collection_set();
6256     assert(cur->in_collection_set(), "bad CS");
6257     cur->set_next_in_collection_set(NULL);
6258     cur->set_in_collection_set(false);
6259 
6260     if (cur->is_young()) {
6261       int index = cur->young_index_in_cset();
6262       assert(index != -1, "invariant");
6263       assert((uint) index < policy->young_cset_region_length(), "invariant");
6264       size_t words_survived = _surviving_young_words[index];
6265       cur->record_surv_words_in_group(words_survived);
6266 
6267       // At this point the we have 'popped' cur from the collection set
6268       // (linked via next_in_collection_set()) but it is still in the
6269       // young list (linked via next_young_region()). Clear the
6270       // _next_young_region field.
6271       cur->set_next_young_region(NULL);
6272     } else {
6273       int index = cur->young_index_in_cset();
6274       assert(index == -1, "invariant");
6275     }
6276 
6277     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6278             (!cur->is_young() && cur->young_index_in_cset() == -1),
6279             "invariant" );
6280 
6281     if (!cur->evacuation_failed()) {
6282       MemRegion used_mr = cur->used_region();
6283 
6284       // And the region is empty.
6285       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6286       pre_used += cur->used();
6287       free_region(cur, &local_free_list, false /* par */, true /* locked */);
6288     } else {
6289       cur->uninstall_surv_rate_group();
6290       if (cur->is_young()) {
6291         cur->set_young_index_in_cset(-1);
6292       }
6293       cur->set_evacuation_failed(false);
6294       // The region is now considered to be old.
6295       cur->set_old();
6296       _old_set.add(cur);
6297       evacuation_info.increment_collectionset_used_after(cur->used());
6298     }
6299     cur = next;
6300   }
6301 
6302   evacuation_info.set_regions_freed(local_free_list.length());
6303   policy->record_max_rs_lengths(rs_lengths);
6304   policy->cset_regions_freed();
6305 
6306   double end_sec = os::elapsedTime();
6307   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6308 
6309   if (non_young) {
6310     non_young_time_ms += elapsed_ms;
6311   } else {
6312     young_time_ms += elapsed_ms;
6313   }
6314 
6315   prepend_to_freelist(&local_free_list);
6316   decrement_summary_bytes(pre_used);
6317   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6318   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6319 }
6320 
6321 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6322  private:
6323   FreeRegionList* _free_region_list;
6324   HeapRegionSet* _proxy_set;
6325   HeapRegionSetCount _humongous_regions_removed;
6326   size_t _freed_bytes;
6327  public:
6328 
6329   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6330     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6331   }
6332 
6333   virtual bool doHeapRegion(HeapRegion* r) {
6334     if (!r->startsHumongous()) {
6335       return false;
6336     }
6337 
6338     G1CollectedHeap* g1h = G1CollectedHeap::heap();
6339 
6340     oop obj = (oop)r->bottom();
6341     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6342 
6343     // The following checks whether the humongous object is live are sufficient.
6344     // The main additional check (in addition to having a reference from the roots
6345     // or the young gen) is whether the humongous object has a remembered set entry.
6346     //
6347     // A humongous object cannot be live if there is no remembered set for it
6348     // because:
6349     // - there can be no references from within humongous starts regions referencing
6350     // the object because we never allocate other objects into them.
6351     // (I.e. there are no intra-region references that may be missed by the
6352     // remembered set)
6353     // - as soon there is a remembered set entry to the humongous starts region
6354     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6355     // until the end of a concurrent mark.
6356     //
6357     // It is not required to check whether the object has been found dead by marking
6358     // or not, in fact it would prevent reclamation within a concurrent cycle, as
6359     // all objects allocated during that time are considered live.
6360     // SATB marking is even more conservative than the remembered set.
6361     // So if at this point in the collection there is no remembered set entry,
6362     // nobody has a reference to it.
6363     // At the start of collection we flush all refinement logs, and remembered sets
6364     // are completely up-to-date wrt to references to the humongous object.
6365     //
6366     // Other implementation considerations:
6367     // - never consider object arrays at this time because they would pose
6368     // considerable effort for cleaning up the the remembered sets. This is
6369     // required because stale remembered sets might reference locations that
6370     // are currently allocated into.
6371     uint region_idx = r->hrm_index();
6372     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6373         !r->rem_set()->is_empty()) {
6374 
6375       if (G1TraceEagerReclaimHumongousObjects) {
6376         gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6377                                region_idx,
6378                                obj->size()*HeapWordSize,
6379                                r->bottom(),
6380                                r->region_num(),
6381                                r->rem_set()->occupied(),
6382                                r->rem_set()->strong_code_roots_list_length(),
6383                                next_bitmap->isMarked(r->bottom()),
6384                                g1h->is_humongous_reclaim_candidate(region_idx),
6385                                obj->is_typeArray()
6386                               );
6387       }
6388 
6389       return false;
6390     }
6391 
6392     guarantee(obj->is_typeArray(),
6393               err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6394                       PTR_FORMAT " is not.",
6395                       r->bottom()));
6396 
6397     if (G1TraceEagerReclaimHumongousObjects) {
6398       gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6399                              region_idx,
6400                              obj->size()*HeapWordSize,
6401                              r->bottom(),
6402                              r->region_num(),
6403                              r->rem_set()->occupied(),
6404                              r->rem_set()->strong_code_roots_list_length(),
6405                              next_bitmap->isMarked(r->bottom()),
6406                              g1h->is_humongous_reclaim_candidate(region_idx),
6407                              obj->is_typeArray()
6408                             );
6409     }
6410     // Need to clear mark bit of the humongous object if already set.
6411     if (next_bitmap->isMarked(r->bottom())) {
6412       next_bitmap->clear(r->bottom());
6413     }
6414     _freed_bytes += r->used();
6415     r->set_containing_set(NULL);
6416     _humongous_regions_removed.increment(1u, r->capacity());
6417     g1h->free_humongous_region(r, _free_region_list, false);
6418 
6419     return false;
6420   }
6421 
6422   HeapRegionSetCount& humongous_free_count() {
6423     return _humongous_regions_removed;
6424   }
6425 
6426   size_t bytes_freed() const {
6427     return _freed_bytes;
6428   }
6429 
6430   size_t humongous_reclaimed() const {
6431     return _humongous_regions_removed.length();
6432   }
6433 };
6434 
6435 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6436   assert_at_safepoint(true);
6437 
6438   if (!G1EagerReclaimHumongousObjects ||
6439       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6440     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6441     return;
6442   }
6443 
6444   double start_time = os::elapsedTime();
6445 
6446   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6447 
6448   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6449   heap_region_iterate(&cl);
6450 
6451   HeapRegionSetCount empty_set;
6452   remove_from_old_sets(empty_set, cl.humongous_free_count());
6453 
6454   G1HRPrinter* hr_printer = _g1h->hr_printer();
6455   if (hr_printer->is_active()) {
6456     FreeRegionListIterator iter(&local_cleanup_list);
6457     while (iter.more_available()) {
6458       HeapRegion* hr = iter.get_next();
6459       hr_printer->cleanup(hr);
6460     }
6461   }
6462 
6463   prepend_to_freelist(&local_cleanup_list);
6464   decrement_summary_bytes(cl.bytes_freed());
6465 
6466   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6467                                                                     cl.humongous_reclaimed());
6468 }
6469 
6470 // This routine is similar to the above but does not record
6471 // any policy statistics or update free lists; we are abandoning
6472 // the current incremental collection set in preparation of a
6473 // full collection. After the full GC we will start to build up
6474 // the incremental collection set again.
6475 // This is only called when we're doing a full collection
6476 // and is immediately followed by the tearing down of the young list.
6477 
6478 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6479   HeapRegion* cur = cs_head;
6480 
6481   while (cur != NULL) {
6482     HeapRegion* next = cur->next_in_collection_set();
6483     assert(cur->in_collection_set(), "bad CS");
6484     cur->set_next_in_collection_set(NULL);
6485     cur->set_in_collection_set(false);
6486     cur->set_young_index_in_cset(-1);
6487     cur = next;
6488   }
6489 }
6490 
6491 void G1CollectedHeap::set_free_regions_coming() {
6492   if (G1ConcRegionFreeingVerbose) {
6493     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6494                            "setting free regions coming");
6495   }
6496 
6497   assert(!free_regions_coming(), "pre-condition");
6498   _free_regions_coming = true;
6499 }
6500 
6501 void G1CollectedHeap::reset_free_regions_coming() {
6502   assert(free_regions_coming(), "pre-condition");
6503 
6504   {
6505     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6506     _free_regions_coming = false;
6507     SecondaryFreeList_lock->notify_all();
6508   }
6509 
6510   if (G1ConcRegionFreeingVerbose) {
6511     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6512                            "reset free regions coming");
6513   }
6514 }
6515 
6516 void G1CollectedHeap::wait_while_free_regions_coming() {
6517   // Most of the time we won't have to wait, so let's do a quick test
6518   // first before we take the lock.
6519   if (!free_regions_coming()) {
6520     return;
6521   }
6522 
6523   if (G1ConcRegionFreeingVerbose) {
6524     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6525                            "waiting for free regions");
6526   }
6527 
6528   {
6529     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6530     while (free_regions_coming()) {
6531       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6532     }
6533   }
6534 
6535   if (G1ConcRegionFreeingVerbose) {
6536     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6537                            "done waiting for free regions");
6538   }
6539 }
6540 
6541 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6542   assert(heap_lock_held_for_gc(),
6543               "the heap lock should already be held by or for this thread");
6544   _young_list->push_region(hr);
6545 }
6546 
6547 class NoYoungRegionsClosure: public HeapRegionClosure {
6548 private:
6549   bool _success;
6550 public:
6551   NoYoungRegionsClosure() : _success(true) { }
6552   bool doHeapRegion(HeapRegion* r) {
6553     if (r->is_young()) {
6554       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6555                              r->bottom(), r->end());
6556       _success = false;
6557     }
6558     return false;
6559   }
6560   bool success() { return _success; }
6561 };
6562 
6563 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6564   bool ret = _young_list->check_list_empty(check_sample);
6565 
6566   if (check_heap) {
6567     NoYoungRegionsClosure closure;
6568     heap_region_iterate(&closure);
6569     ret = ret && closure.success();
6570   }
6571 
6572   return ret;
6573 }
6574 
6575 class TearDownRegionSetsClosure : public HeapRegionClosure {
6576 private:
6577   HeapRegionSet *_old_set;
6578 
6579 public:
6580   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6581 
6582   bool doHeapRegion(HeapRegion* r) {
6583     if (r->is_old()) {
6584       _old_set->remove(r);
6585     } else {
6586       // We ignore free regions, we'll empty the free list afterwards.
6587       // We ignore young regions, we'll empty the young list afterwards.
6588       // We ignore humongous regions, we're not tearing down the
6589       // humongous regions set.
6590       assert(r->is_free() || r->is_young() || r->isHumongous(),
6591              "it cannot be another type");
6592     }
6593     return false;
6594   }
6595 
6596   ~TearDownRegionSetsClosure() {
6597     assert(_old_set->is_empty(), "post-condition");
6598   }
6599 };
6600 
6601 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6602   assert_at_safepoint(true /* should_be_vm_thread */);
6603 
6604   if (!free_list_only) {
6605     TearDownRegionSetsClosure cl(&_old_set);
6606     heap_region_iterate(&cl);
6607 
6608     // Note that emptying the _young_list is postponed and instead done as
6609     // the first step when rebuilding the regions sets again. The reason for
6610     // this is that during a full GC string deduplication needs to know if
6611     // a collected region was young or old when the full GC was initiated.
6612   }
6613   _hrm.remove_all_free_regions();
6614 }
6615 
6616 class RebuildRegionSetsClosure : public HeapRegionClosure {
6617 private:
6618   bool            _free_list_only;
6619   HeapRegionSet*   _old_set;
6620   HeapRegionManager*   _hrm;
6621   size_t          _total_used;
6622 
6623 public:
6624   RebuildRegionSetsClosure(bool free_list_only,
6625                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6626     _free_list_only(free_list_only),
6627     _old_set(old_set), _hrm(hrm), _total_used(0) {
6628     assert(_hrm->num_free_regions() == 0, "pre-condition");
6629     if (!free_list_only) {
6630       assert(_old_set->is_empty(), "pre-condition");
6631     }
6632   }
6633 
6634   bool doHeapRegion(HeapRegion* r) {
6635     if (r->continuesHumongous()) {
6636       return false;
6637     }
6638 
6639     if (r->is_empty()) {
6640       // Add free regions to the free list
6641       r->set_free();
6642       r->set_allocation_context(AllocationContext::system());
6643       _hrm->insert_into_free_list(r);
6644     } else if (!_free_list_only) {
6645       assert(!r->is_young(), "we should not come across young regions");
6646 
6647       if (r->isHumongous()) {
6648         // We ignore humongous regions, we left the humongous set unchanged
6649       } else {
6650         // Objects that were compacted would have ended up on regions
6651         // that were previously old or free.
6652         assert(r->is_free() || r->is_old(), "invariant");
6653         // We now consider them old, so register as such.
6654         r->set_old();
6655         _old_set->add(r);
6656       }
6657       _total_used += r->used();
6658     }
6659 
6660     return false;
6661   }
6662 
6663   size_t total_used() {
6664     return _total_used;
6665   }
6666 };
6667 
6668 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6669   assert_at_safepoint(true /* should_be_vm_thread */);
6670 
6671   if (!free_list_only) {
6672     _young_list->empty_list();
6673   }
6674 
6675   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6676   heap_region_iterate(&cl);
6677 
6678   if (!free_list_only) {
6679     _allocator->set_used(cl.total_used());
6680   }
6681   assert(_allocator->used_unlocked() == recalculate_used(),
6682          err_msg("inconsistent _allocator->used_unlocked(), "
6683                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6684                  _allocator->used_unlocked(), recalculate_used()));
6685 }
6686 
6687 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6688   _refine_cte_cl->set_concurrent(concurrent);
6689 }
6690 
6691 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6692   HeapRegion* hr = heap_region_containing(p);
6693   return hr->is_in(p);
6694 }
6695 
6696 // Methods for the mutator alloc region
6697 
6698 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6699                                                       bool force) {
6700   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6701   assert(!force || g1_policy()->can_expand_young_list(),
6702          "if force is true we should be able to expand the young list");
6703   bool young_list_full = g1_policy()->is_young_list_full();
6704   if (force || !young_list_full) {
6705     HeapRegion* new_alloc_region = new_region(word_size,
6706                                               false /* is_old */,
6707                                               false /* do_expand */);
6708     if (new_alloc_region != NULL) {
6709       set_region_short_lived_locked(new_alloc_region);
6710       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6711       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6712       return new_alloc_region;
6713     }
6714   }
6715   return NULL;
6716 }
6717 
6718 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6719                                                   size_t allocated_bytes) {
6720   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6721   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6722 
6723   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6724   _allocator->increase_used(allocated_bytes);
6725   _hr_printer.retire(alloc_region);
6726   // We update the eden sizes here, when the region is retired,
6727   // instead of when it's allocated, since this is the point that its
6728   // used space has been recored in _summary_bytes_used.
6729   g1mm()->update_eden_size();
6730 }
6731 
6732 void G1CollectedHeap::set_par_threads() {
6733   // Don't change the number of workers.  Use the value previously set
6734   // in the workgroup.
6735   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6736   uint n_workers = workers()->active_workers();
6737   assert(UseDynamicNumberOfGCThreads ||
6738            n_workers == workers()->total_workers(),
6739       "Otherwise should be using the total number of workers");
6740   if (n_workers == 0) {
6741     assert(false, "Should have been set in prior evacuation pause.");
6742     n_workers = ParallelGCThreads;
6743     workers()->set_active_workers(n_workers);
6744   }
6745   set_par_threads(n_workers);
6746 }
6747 
6748 // Methods for the GC alloc regions
6749 
6750 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6751                                                  uint count,
6752                                                  InCSetState dest) {
6753   assert(FreeList_lock->owned_by_self(), "pre-condition");
6754 
6755   if (count < g1_policy()->max_regions(dest)) {
6756     const bool is_survivor = (dest.is_young());
6757     HeapRegion* new_alloc_region = new_region(word_size,
6758                                               !is_survivor,
6759                                               true /* do_expand */);
6760     if (new_alloc_region != NULL) {
6761       // We really only need to do this for old regions given that we
6762       // should never scan survivors. But it doesn't hurt to do it
6763       // for survivors too.
6764       new_alloc_region->record_timestamp();
6765       if (is_survivor) {
6766         new_alloc_region->set_survivor();
6767         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6768         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6769       } else {
6770         new_alloc_region->set_old();
6771         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6772         check_bitmaps("Old Region Allocation", new_alloc_region);
6773       }
6774       bool during_im = g1_policy()->during_initial_mark_pause();
6775       new_alloc_region->note_start_of_copying(during_im);
6776       return new_alloc_region;
6777     }
6778   }
6779   return NULL;
6780 }
6781 
6782 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6783                                              size_t allocated_bytes,
6784                                              InCSetState dest) {
6785   bool during_im = g1_policy()->during_initial_mark_pause();
6786   alloc_region->note_end_of_copying(during_im);
6787   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6788   if (dest.is_young()) {
6789     young_list()->add_survivor_region(alloc_region);
6790   } else {
6791     _old_set.add(alloc_region);
6792   }
6793   _hr_printer.retire(alloc_region);
6794 }
6795 
6796 // Heap region set verification
6797 
6798 class VerifyRegionListsClosure : public HeapRegionClosure {
6799 private:
6800   HeapRegionSet*   _old_set;
6801   HeapRegionSet*   _humongous_set;
6802   HeapRegionManager*   _hrm;
6803 
6804 public:
6805   HeapRegionSetCount _old_count;
6806   HeapRegionSetCount _humongous_count;
6807   HeapRegionSetCount _free_count;
6808 
6809   VerifyRegionListsClosure(HeapRegionSet* old_set,
6810                            HeapRegionSet* humongous_set,
6811                            HeapRegionManager* hrm) :
6812     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6813     _old_count(), _humongous_count(), _free_count(){ }
6814 
6815   bool doHeapRegion(HeapRegion* hr) {
6816     if (hr->continuesHumongous()) {
6817       return false;
6818     }
6819 
6820     if (hr->is_young()) {
6821       // TODO
6822     } else if (hr->startsHumongous()) {
6823       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6824       _humongous_count.increment(1u, hr->capacity());
6825     } else if (hr->is_empty()) {
6826       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6827       _free_count.increment(1u, hr->capacity());
6828     } else if (hr->is_old()) {
6829       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6830       _old_count.increment(1u, hr->capacity());
6831     } else {
6832       ShouldNotReachHere();
6833     }
6834     return false;
6835   }
6836 
6837   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6838     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6839     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6840         old_set->total_capacity_bytes(), _old_count.capacity()));
6841 
6842     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6843     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6844         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6845 
6846     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()));
6847     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6848         free_list->total_capacity_bytes(), _free_count.capacity()));
6849   }
6850 };
6851 
6852 void G1CollectedHeap::verify_region_sets() {
6853   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6854 
6855   // First, check the explicit lists.
6856   _hrm.verify();
6857   {
6858     // Given that a concurrent operation might be adding regions to
6859     // the secondary free list we have to take the lock before
6860     // verifying it.
6861     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6862     _secondary_free_list.verify_list();
6863   }
6864 
6865   // If a concurrent region freeing operation is in progress it will
6866   // be difficult to correctly attributed any free regions we come
6867   // across to the correct free list given that they might belong to
6868   // one of several (free_list, secondary_free_list, any local lists,
6869   // etc.). So, if that's the case we will skip the rest of the
6870   // verification operation. Alternatively, waiting for the concurrent
6871   // operation to complete will have a non-trivial effect on the GC's
6872   // operation (no concurrent operation will last longer than the
6873   // interval between two calls to verification) and it might hide
6874   // any issues that we would like to catch during testing.
6875   if (free_regions_coming()) {
6876     return;
6877   }
6878 
6879   // Make sure we append the secondary_free_list on the free_list so
6880   // that all free regions we will come across can be safely
6881   // attributed to the free_list.
6882   append_secondary_free_list_if_not_empty_with_lock();
6883 
6884   // Finally, make sure that the region accounting in the lists is
6885   // consistent with what we see in the heap.
6886 
6887   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6888   heap_region_iterate(&cl);
6889   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6890 }
6891 
6892 // Optimized nmethod scanning
6893 
6894 class RegisterNMethodOopClosure: public OopClosure {
6895   G1CollectedHeap* _g1h;
6896   nmethod* _nm;
6897 
6898   template <class T> void do_oop_work(T* p) {
6899     T heap_oop = oopDesc::load_heap_oop(p);
6900     if (!oopDesc::is_null(heap_oop)) {
6901       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6902       HeapRegion* hr = _g1h->heap_region_containing(obj);
6903       assert(!hr->continuesHumongous(),
6904              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6905                      " starting at "HR_FORMAT,
6906                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6907 
6908       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6909       hr->add_strong_code_root_locked(_nm);
6910     }
6911   }
6912 
6913 public:
6914   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6915     _g1h(g1h), _nm(nm) {}
6916 
6917   void do_oop(oop* p)       { do_oop_work(p); }
6918   void do_oop(narrowOop* p) { do_oop_work(p); }
6919 };
6920 
6921 class UnregisterNMethodOopClosure: public OopClosure {
6922   G1CollectedHeap* _g1h;
6923   nmethod* _nm;
6924 
6925   template <class T> void do_oop_work(T* p) {
6926     T heap_oop = oopDesc::load_heap_oop(p);
6927     if (!oopDesc::is_null(heap_oop)) {
6928       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6929       HeapRegion* hr = _g1h->heap_region_containing(obj);
6930       assert(!hr->continuesHumongous(),
6931              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6932                      " starting at "HR_FORMAT,
6933                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6934 
6935       hr->remove_strong_code_root(_nm);
6936     }
6937   }
6938 
6939 public:
6940   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6941     _g1h(g1h), _nm(nm) {}
6942 
6943   void do_oop(oop* p)       { do_oop_work(p); }
6944   void do_oop(narrowOop* p) { do_oop_work(p); }
6945 };
6946 
6947 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6948   CollectedHeap::register_nmethod(nm);
6949 
6950   guarantee(nm != NULL, "sanity");
6951   RegisterNMethodOopClosure reg_cl(this, nm);
6952   nm->oops_do(&reg_cl);
6953 }
6954 
6955 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6956   CollectedHeap::unregister_nmethod(nm);
6957 
6958   guarantee(nm != NULL, "sanity");
6959   UnregisterNMethodOopClosure reg_cl(this, nm);
6960   nm->oops_do(&reg_cl, true);
6961 }
6962 
6963 void G1CollectedHeap::purge_code_root_memory() {
6964   double purge_start = os::elapsedTime();
6965   G1CodeRootSet::purge();
6966   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6967   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6968 }
6969 
6970 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6971   G1CollectedHeap* _g1h;
6972 
6973 public:
6974   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6975     _g1h(g1h) {}
6976 
6977   void do_code_blob(CodeBlob* cb) {
6978     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6979     if (nm == NULL) {
6980       return;
6981     }
6982 
6983     if (ScavengeRootsInCode) {
6984       _g1h->register_nmethod(nm);
6985     }
6986   }
6987 };
6988 
6989 void G1CollectedHeap::rebuild_strong_code_roots() {
6990   RebuildStrongCodeRootClosure blob_cl(this);
6991   CodeCache::blobs_do(&blob_cl);
6992 }