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(!GCCause::is_user_requested_gc(gc_cause()) || 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::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2333     case GCCause::_g1_humongous_allocation: return true;
2334     case GCCause::_update_allocation_context_stats_inc: 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         r->rem_set()->clear_locked();
3771       }
3772       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3773     }
3774     _total_humongous++;
3775 
3776     return false;
3777   }
3778 
3779   size_t total_humongous() const { return _total_humongous; }
3780   size_t candidate_humongous() const { return _candidate_humongous; }
3781 
3782   void flush_rem_set_entries() { _dcq.flush(); }
3783 };
3784 
3785 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3786   if (!G1EagerReclaimHumongousObjects) {
3787     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3788     return;
3789   }
3790   double time = os::elapsed_counter();
3791 
3792   // Collect reclaim candidate information and register candidates with cset.
3793   RegisterHumongousWithInCSetFastTestClosure cl;
3794   heap_region_iterate(&cl);
3795 
3796   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3797   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3798                                                                   cl.total_humongous(),
3799                                                                   cl.candidate_humongous());
3800   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3801 
3802   // Finally flush all remembered set entries to re-check into the global DCQS.
3803   cl.flush_rem_set_entries();
3804 }
3805 
3806 void
3807 G1CollectedHeap::setup_surviving_young_words() {
3808   assert(_surviving_young_words == NULL, "pre-condition");
3809   uint array_length = g1_policy()->young_cset_region_length();
3810   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3811   if (_surviving_young_words == NULL) {
3812     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3813                           "Not enough space for young surv words summary.");
3814   }
3815   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3816 #ifdef ASSERT
3817   for (uint i = 0;  i < array_length; ++i) {
3818     assert( _surviving_young_words[i] == 0, "memset above" );
3819   }
3820 #endif // !ASSERT
3821 }
3822 
3823 void
3824 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3825   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3826   uint array_length = g1_policy()->young_cset_region_length();
3827   for (uint i = 0; i < array_length; ++i) {
3828     _surviving_young_words[i] += surv_young_words[i];
3829   }
3830 }
3831 
3832 void
3833 G1CollectedHeap::cleanup_surviving_young_words() {
3834   guarantee( _surviving_young_words != NULL, "pre-condition" );
3835   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3836   _surviving_young_words = NULL;
3837 }
3838 
3839 #ifdef ASSERT
3840 class VerifyCSetClosure: public HeapRegionClosure {
3841 public:
3842   bool doHeapRegion(HeapRegion* hr) {
3843     // Here we check that the CSet region's RSet is ready for parallel
3844     // iteration. The fields that we'll verify are only manipulated
3845     // when the region is part of a CSet and is collected. Afterwards,
3846     // we reset these fields when we clear the region's RSet (when the
3847     // region is freed) so they are ready when the region is
3848     // re-allocated. The only exception to this is if there's an
3849     // evacuation failure and instead of freeing the region we leave
3850     // it in the heap. In that case, we reset these fields during
3851     // evacuation failure handling.
3852     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3853 
3854     // Here's a good place to add any other checks we'd like to
3855     // perform on CSet regions.
3856     return false;
3857   }
3858 };
3859 #endif // ASSERT
3860 
3861 #if TASKQUEUE_STATS
3862 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3863   st->print_raw_cr("GC Task Stats");
3864   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3865   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3866 }
3867 
3868 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3869   print_taskqueue_stats_hdr(st);
3870 
3871   TaskQueueStats totals;
3872   const int n = workers() != NULL ? workers()->total_workers() : 1;
3873   for (int i = 0; i < n; ++i) {
3874     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3875     totals += task_queue(i)->stats;
3876   }
3877   st->print_raw("tot "); totals.print(st); st->cr();
3878 
3879   DEBUG_ONLY(totals.verify());
3880 }
3881 
3882 void G1CollectedHeap::reset_taskqueue_stats() {
3883   const int n = workers() != NULL ? workers()->total_workers() : 1;
3884   for (int i = 0; i < n; ++i) {
3885     task_queue(i)->stats.reset();
3886   }
3887 }
3888 #endif // TASKQUEUE_STATS
3889 
3890 void G1CollectedHeap::log_gc_header() {
3891   if (!G1Log::fine()) {
3892     return;
3893   }
3894 
3895   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3896 
3897   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3898     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3899     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3900 
3901   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3902 }
3903 
3904 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3905   if (!G1Log::fine()) {
3906     return;
3907   }
3908 
3909   if (G1Log::finer()) {
3910     if (evacuation_failed()) {
3911       gclog_or_tty->print(" (to-space exhausted)");
3912     }
3913     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3914     g1_policy()->phase_times()->note_gc_end();
3915     g1_policy()->phase_times()->print(pause_time_sec);
3916     g1_policy()->print_detailed_heap_transition();
3917   } else {
3918     if (evacuation_failed()) {
3919       gclog_or_tty->print("--");
3920     }
3921     g1_policy()->print_heap_transition();
3922     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3923   }
3924   gclog_or_tty->flush();
3925 }
3926 
3927 bool
3928 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3929   assert_at_safepoint(true /* should_be_vm_thread */);
3930   guarantee(!is_gc_active(), "collection is not reentrant");
3931 
3932   if (GC_locker::check_active_before_gc()) {
3933     return false;
3934   }
3935 
3936   _gc_timer_stw->register_gc_start();
3937 
3938   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3939 
3940   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3941   ResourceMark rm;
3942 
3943   print_heap_before_gc();
3944   trace_heap_before_gc(_gc_tracer_stw);
3945 
3946   verify_region_sets_optional();
3947   verify_dirty_young_regions();
3948 
3949   // This call will decide whether this pause is an initial-mark
3950   // pause. If it is, during_initial_mark_pause() will return true
3951   // for the duration of this pause.
3952   g1_policy()->decide_on_conc_mark_initiation();
3953 
3954   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3955   assert(!g1_policy()->during_initial_mark_pause() ||
3956           g1_policy()->gcs_are_young(), "sanity");
3957 
3958   // We also do not allow mixed GCs during marking.
3959   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3960 
3961   // Record whether this pause is an initial mark. When the current
3962   // thread has completed its logging output and it's safe to signal
3963   // the CM thread, the flag's value in the policy has been reset.
3964   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3965 
3966   // Inner scope for scope based logging, timers, and stats collection
3967   {
3968     EvacuationInfo evacuation_info;
3969 
3970     if (g1_policy()->during_initial_mark_pause()) {
3971       // We are about to start a marking cycle, so we increment the
3972       // full collection counter.
3973       increment_old_marking_cycles_started();
3974       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3975     }
3976 
3977     _gc_tracer_stw->report_yc_type(yc_type());
3978 
3979     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3980 
3981     uint active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3982                                 workers()->active_workers() : 1);
3983     double pause_start_sec = os::elapsedTime();
3984     g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3985     log_gc_header();
3986 
3987     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3988     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3989 
3990     // If the secondary_free_list is not empty, append it to the
3991     // free_list. No need to wait for the cleanup operation to finish;
3992     // the region allocation code will check the secondary_free_list
3993     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3994     // set, skip this step so that the region allocation code has to
3995     // get entries from the secondary_free_list.
3996     if (!G1StressConcRegionFreeing) {
3997       append_secondary_free_list_if_not_empty_with_lock();
3998     }
3999 
4000     assert(check_young_list_well_formed(), "young list should be well formed");
4001     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
4002            "sanity check");
4003 
4004     // Don't dynamically change the number of GC threads this early.  A value of
4005     // 0 is used to indicate serial work.  When parallel work is done,
4006     // it will be set.
4007 
4008     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4009       IsGCActiveMark x;
4010 
4011       gc_prologue(false);
4012       increment_total_collections(false /* full gc */);
4013       increment_gc_time_stamp();
4014 
4015       verify_before_gc();
4016       check_bitmaps("GC Start");
4017 
4018       COMPILER2_PRESENT(DerivedPointerTable::clear());
4019 
4020       // Please see comment in g1CollectedHeap.hpp and
4021       // G1CollectedHeap::ref_processing_init() to see how
4022       // reference processing currently works in G1.
4023 
4024       // Enable discovery in the STW reference processor
4025       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4026                                             true /*verify_no_refs*/);
4027 
4028       {
4029         // We want to temporarily turn off discovery by the
4030         // CM ref processor, if necessary, and turn it back on
4031         // on again later if we do. Using a scoped
4032         // NoRefDiscovery object will do this.
4033         NoRefDiscovery no_cm_discovery(ref_processor_cm());
4034 
4035         // Forget the current alloc region (we might even choose it to be part
4036         // of the collection set!).
4037         _allocator->release_mutator_alloc_region();
4038 
4039         // We should call this after we retire the mutator alloc
4040         // region(s) so that all the ALLOC / RETIRE events are generated
4041         // before the start GC event.
4042         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4043 
4044         // This timing is only used by the ergonomics to handle our pause target.
4045         // It is unclear why this should not include the full pause. We will
4046         // investigate this in CR 7178365.
4047         //
4048         // Preserving the old comment here if that helps the investigation:
4049         //
4050         // The elapsed time induced by the start time below deliberately elides
4051         // the possible verification above.
4052         double sample_start_time_sec = os::elapsedTime();
4053 
4054 #if YOUNG_LIST_VERBOSE
4055         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4056         _young_list->print();
4057         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4058 #endif // YOUNG_LIST_VERBOSE
4059 
4060         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4061 
4062         double scan_wait_start = os::elapsedTime();
4063         // We have to wait until the CM threads finish scanning the
4064         // root regions as it's the only way to ensure that all the
4065         // objects on them have been correctly scanned before we start
4066         // moving them during the GC.
4067         bool waited = _cm->root_regions()->wait_until_scan_finished();
4068         double wait_time_ms = 0.0;
4069         if (waited) {
4070           double scan_wait_end = os::elapsedTime();
4071           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4072         }
4073         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4074 
4075 #if YOUNG_LIST_VERBOSE
4076         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4077         _young_list->print();
4078 #endif // YOUNG_LIST_VERBOSE
4079 
4080         if (g1_policy()->during_initial_mark_pause()) {
4081           concurrent_mark()->checkpointRootsInitialPre();
4082         }
4083 
4084 #if YOUNG_LIST_VERBOSE
4085         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4086         _young_list->print();
4087         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4088 #endif // YOUNG_LIST_VERBOSE
4089 
4090         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4091 
4092         register_humongous_regions_with_in_cset_fast_test();
4093 
4094         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4095 
4096         _cm->note_start_of_gc();
4097         // We call this after finalize_cset() to
4098         // ensure that the CSet has been finalized.
4099         _cm->verify_no_cset_oops();
4100 
4101         if (_hr_printer.is_active()) {
4102           HeapRegion* hr = g1_policy()->collection_set();
4103           while (hr != NULL) {
4104             _hr_printer.cset(hr);
4105             hr = hr->next_in_collection_set();
4106           }
4107         }
4108 
4109 #ifdef ASSERT
4110         VerifyCSetClosure cl;
4111         collection_set_iterate(&cl);
4112 #endif // ASSERT
4113 
4114         setup_surviving_young_words();
4115 
4116         // Initialize the GC alloc regions.
4117         _allocator->init_gc_alloc_regions(evacuation_info);
4118 
4119         // Actually do the work...
4120         evacuate_collection_set(evacuation_info);
4121 
4122         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4123 
4124         eagerly_reclaim_humongous_regions();
4125 
4126         g1_policy()->clear_collection_set();
4127 
4128         cleanup_surviving_young_words();
4129 
4130         // Start a new incremental collection set for the next pause.
4131         g1_policy()->start_incremental_cset_building();
4132 
4133         clear_cset_fast_test();
4134 
4135         _young_list->reset_sampled_info();
4136 
4137         // Don't check the whole heap at this point as the
4138         // GC alloc regions from this pause have been tagged
4139         // as survivors and moved on to the survivor list.
4140         // Survivor regions will fail the !is_young() check.
4141         assert(check_young_list_empty(false /* check_heap */),
4142           "young list should be empty");
4143 
4144 #if YOUNG_LIST_VERBOSE
4145         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4146         _young_list->print();
4147 #endif // YOUNG_LIST_VERBOSE
4148 
4149         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4150                                              _young_list->first_survivor_region(),
4151                                              _young_list->last_survivor_region());
4152 
4153         _young_list->reset_auxilary_lists();
4154 
4155         if (evacuation_failed()) {
4156           _allocator->set_used(recalculate_used());
4157           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4158           for (uint i = 0; i < n_queues; i++) {
4159             if (_evacuation_failed_info_array[i].has_failed()) {
4160               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4161             }
4162           }
4163         } else {
4164           // The "used" of the the collection set have already been subtracted
4165           // when they were freed.  Add in the bytes evacuated.
4166           _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4167         }
4168 
4169         if (g1_policy()->during_initial_mark_pause()) {
4170           // We have to do this before we notify the CM threads that
4171           // they can start working to make sure that all the
4172           // appropriate initialization is done on the CM object.
4173           concurrent_mark()->checkpointRootsInitialPost();
4174           set_marking_started();
4175           // Note that we don't actually trigger the CM thread at
4176           // this point. We do that later when we're sure that
4177           // the current thread has completed its logging output.
4178         }
4179 
4180         allocate_dummy_regions();
4181 
4182 #if YOUNG_LIST_VERBOSE
4183         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4184         _young_list->print();
4185         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4186 #endif // YOUNG_LIST_VERBOSE
4187 
4188         _allocator->init_mutator_alloc_region();
4189 
4190         {
4191           size_t expand_bytes = g1_policy()->expansion_amount();
4192           if (expand_bytes > 0) {
4193             size_t bytes_before = capacity();
4194             // No need for an ergo verbose message here,
4195             // expansion_amount() does this when it returns a value > 0.
4196             if (!expand(expand_bytes)) {
4197               // We failed to expand the heap. Cannot do anything about it.
4198             }
4199           }
4200         }
4201 
4202         // We redo the verification but now wrt to the new CSet which
4203         // has just got initialized after the previous CSet was freed.
4204         _cm->verify_no_cset_oops();
4205         _cm->note_end_of_gc();
4206 
4207         // This timing is only used by the ergonomics to handle our pause target.
4208         // It is unclear why this should not include the full pause. We will
4209         // investigate this in CR 7178365.
4210         double sample_end_time_sec = os::elapsedTime();
4211         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4212         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4213 
4214         MemoryService::track_memory_usage();
4215 
4216         // In prepare_for_verify() below we'll need to scan the deferred
4217         // update buffers to bring the RSets up-to-date if
4218         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4219         // the update buffers we'll probably need to scan cards on the
4220         // regions we just allocated to (i.e., the GC alloc
4221         // regions). However, during the last GC we called
4222         // set_saved_mark() on all the GC alloc regions, so card
4223         // scanning might skip the [saved_mark_word()...top()] area of
4224         // those regions (i.e., the area we allocated objects into
4225         // during the last GC). But it shouldn't. Given that
4226         // saved_mark_word() is conditional on whether the GC time stamp
4227         // on the region is current or not, by incrementing the GC time
4228         // stamp here we invalidate all the GC time stamps on all the
4229         // regions and saved_mark_word() will simply return top() for
4230         // all the regions. This is a nicer way of ensuring this rather
4231         // than iterating over the regions and fixing them. In fact, the
4232         // GC time stamp increment here also ensures that
4233         // saved_mark_word() will return top() between pauses, i.e.,
4234         // during concurrent refinement. So we don't need the
4235         // is_gc_active() check to decided which top to use when
4236         // scanning cards (see CR 7039627).
4237         increment_gc_time_stamp();
4238 
4239         verify_after_gc();
4240         check_bitmaps("GC End");
4241 
4242         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4243         ref_processor_stw()->verify_no_references_recorded();
4244 
4245         // CM reference discovery will be re-enabled if necessary.
4246       }
4247 
4248       // We should do this after we potentially expand the heap so
4249       // that all the COMMIT events are generated before the end GC
4250       // event, and after we retire the GC alloc regions so that all
4251       // RETIRE events are generated before the end GC event.
4252       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4253 
4254 #ifdef TRACESPINNING
4255       ParallelTaskTerminator::print_termination_counts();
4256 #endif
4257 
4258       gc_epilogue(false);
4259     }
4260 
4261     // Print the remainder of the GC log output.
4262     log_gc_footer(os::elapsedTime() - pause_start_sec);
4263 
4264     // It is not yet to safe to tell the concurrent mark to
4265     // start as we have some optional output below. We don't want the
4266     // output from the concurrent mark thread interfering with this
4267     // logging output either.
4268 
4269     _hrm.verify_optional();
4270     verify_region_sets_optional();
4271 
4272     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4273     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4274 
4275     print_heap_after_gc();
4276     trace_heap_after_gc(_gc_tracer_stw);
4277 
4278     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4279     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4280     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4281     // before any GC notifications are raised.
4282     g1mm()->update_sizes();
4283 
4284     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4285     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4286     _gc_timer_stw->register_gc_end();
4287     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4288   }
4289   // It should now be safe to tell the concurrent mark thread to start
4290   // without its logging output interfering with the logging output
4291   // that came from the pause.
4292 
4293   if (should_start_conc_mark) {
4294     // CAUTION: after the doConcurrentMark() call below,
4295     // the concurrent marking thread(s) could be running
4296     // concurrently with us. Make sure that anything after
4297     // this point does not assume that we are the only GC thread
4298     // running. Note: of course, the actual marking work will
4299     // not start until the safepoint itself is released in
4300     // SuspendibleThreadSet::desynchronize().
4301     doConcurrentMark();
4302   }
4303 
4304   return true;
4305 }
4306 
4307 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4308   _drain_in_progress = false;
4309   set_evac_failure_closure(cl);
4310   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4311 }
4312 
4313 void G1CollectedHeap::finalize_for_evac_failure() {
4314   assert(_evac_failure_scan_stack != NULL &&
4315          _evac_failure_scan_stack->length() == 0,
4316          "Postcondition");
4317   assert(!_drain_in_progress, "Postcondition");
4318   delete _evac_failure_scan_stack;
4319   _evac_failure_scan_stack = NULL;
4320 }
4321 
4322 void G1CollectedHeap::remove_self_forwarding_pointers() {
4323   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4324 
4325   double remove_self_forwards_start = os::elapsedTime();
4326 
4327   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4328 
4329   if (G1CollectedHeap::use_parallel_gc_threads()) {
4330     set_par_threads();
4331     workers()->run_task(&rsfp_task);
4332     set_par_threads(0);
4333   } else {
4334     rsfp_task.work(0);
4335   }
4336 
4337   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4338 
4339   // Reset the claim values in the regions in the collection set.
4340   reset_cset_heap_region_claim_values();
4341 
4342   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4343 
4344   // Now restore saved marks, if any.
4345   assert(_objs_with_preserved_marks.size() ==
4346             _preserved_marks_of_objs.size(), "Both or none.");
4347   while (!_objs_with_preserved_marks.is_empty()) {
4348     oop obj = _objs_with_preserved_marks.pop();
4349     markOop m = _preserved_marks_of_objs.pop();
4350     obj->set_mark(m);
4351   }
4352   _objs_with_preserved_marks.clear(true);
4353   _preserved_marks_of_objs.clear(true);
4354 
4355   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4356 }
4357 
4358 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4359   _evac_failure_scan_stack->push(obj);
4360 }
4361 
4362 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4363   assert(_evac_failure_scan_stack != NULL, "precondition");
4364 
4365   while (_evac_failure_scan_stack->length() > 0) {
4366      oop obj = _evac_failure_scan_stack->pop();
4367      _evac_failure_closure->set_region(heap_region_containing(obj));
4368      obj->oop_iterate_backwards(_evac_failure_closure);
4369   }
4370 }
4371 
4372 oop
4373 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4374                                                oop old) {
4375   assert(obj_in_cs(old),
4376          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4377                  (HeapWord*) old));
4378   markOop m = old->mark();
4379   oop forward_ptr = old->forward_to_atomic(old);
4380   if (forward_ptr == NULL) {
4381     // Forward-to-self succeeded.
4382     assert(_par_scan_state != NULL, "par scan state");
4383     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4384     uint queue_num = _par_scan_state->queue_num();
4385 
4386     _evacuation_failed = true;
4387     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4388     if (_evac_failure_closure != cl) {
4389       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4390       assert(!_drain_in_progress,
4391              "Should only be true while someone holds the lock.");
4392       // Set the global evac-failure closure to the current thread's.
4393       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4394       set_evac_failure_closure(cl);
4395       // Now do the common part.
4396       handle_evacuation_failure_common(old, m);
4397       // Reset to NULL.
4398       set_evac_failure_closure(NULL);
4399     } else {
4400       // The lock is already held, and this is recursive.
4401       assert(_drain_in_progress, "This should only be the recursive case.");
4402       handle_evacuation_failure_common(old, m);
4403     }
4404     return old;
4405   } else {
4406     // Forward-to-self failed. Either someone else managed to allocate
4407     // space for this object (old != forward_ptr) or they beat us in
4408     // self-forwarding it (old == forward_ptr).
4409     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4410            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4411                    "should not be in the CSet",
4412                    (HeapWord*) old, (HeapWord*) forward_ptr));
4413     return forward_ptr;
4414   }
4415 }
4416 
4417 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4418   preserve_mark_if_necessary(old, m);
4419 
4420   HeapRegion* r = heap_region_containing(old);
4421   if (!r->evacuation_failed()) {
4422     r->set_evacuation_failed(true);
4423     _hr_printer.evac_failure(r);
4424   }
4425 
4426   push_on_evac_failure_scan_stack(old);
4427 
4428   if (!_drain_in_progress) {
4429     // prevent recursion in copy_to_survivor_space()
4430     _drain_in_progress = true;
4431     drain_evac_failure_scan_stack();
4432     _drain_in_progress = false;
4433   }
4434 }
4435 
4436 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4437   assert(evacuation_failed(), "Oversaving!");
4438   // We want to call the "for_promotion_failure" version only in the
4439   // case of a promotion failure.
4440   if (m->must_be_preserved_for_promotion_failure(obj)) {
4441     _objs_with_preserved_marks.push(obj);
4442     _preserved_marks_of_objs.push(m);
4443   }
4444 }
4445 
4446 void G1ParCopyHelper::mark_object(oop obj) {
4447   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4448 
4449   // We know that the object is not moving so it's safe to read its size.
4450   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4451 }
4452 
4453 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4454   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4455   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4456   assert(from_obj != to_obj, "should not be self-forwarded");
4457 
4458   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4459   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4460 
4461   // The object might be in the process of being copied by another
4462   // worker so we cannot trust that its to-space image is
4463   // well-formed. So we have to read its size from its from-space
4464   // image which we know should not be changing.
4465   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4466 }
4467 
4468 template <class T>
4469 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4470   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4471     _scanned_klass->record_modified_oops();
4472   }
4473 }
4474 
4475 template <G1Barrier barrier, G1Mark do_mark_object>
4476 template <class T>
4477 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4478   T heap_oop = oopDesc::load_heap_oop(p);
4479 
4480   if (oopDesc::is_null(heap_oop)) {
4481     return;
4482   }
4483 
4484   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4485 
4486   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4487 
4488   const InCSetState state = _g1->in_cset_state(obj);
4489   if (state.is_in_cset()) {
4490     oop forwardee;
4491     markOop m = obj->mark();
4492     if (m->is_marked()) {
4493       forwardee = (oop) m->decode_pointer();
4494     } else {
4495       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4496     }
4497     assert(forwardee != NULL, "forwardee should not be NULL");
4498     oopDesc::encode_store_heap_oop(p, forwardee);
4499     if (do_mark_object != G1MarkNone && forwardee != obj) {
4500       // If the object is self-forwarded we don't need to explicitly
4501       // mark it, the evacuation failure protocol will do so.
4502       mark_forwarded_object(obj, forwardee);
4503     }
4504 
4505     if (barrier == G1BarrierKlass) {
4506       do_klass_barrier(p, forwardee);
4507     }
4508   } else {
4509     if (state.is_humongous()) {
4510       _g1->set_humongous_is_live(obj);
4511     }
4512     // The object is not in collection set. If we're a root scanning
4513     // closure during an initial mark pause then attempt to mark the object.
4514     if (do_mark_object == G1MarkFromRoot) {
4515       mark_object(obj);
4516     }
4517   }
4518 
4519   if (barrier == G1BarrierEvac) {
4520     _par_scan_state->update_rs(_from, p, _worker_id);
4521   }
4522 }
4523 
4524 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4525 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4526 
4527 class G1ParEvacuateFollowersClosure : public VoidClosure {
4528 protected:
4529   G1CollectedHeap*              _g1h;
4530   G1ParScanThreadState*         _par_scan_state;
4531   RefToScanQueueSet*            _queues;
4532   ParallelTaskTerminator*       _terminator;
4533 
4534   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4535   RefToScanQueueSet*      queues()         { return _queues; }
4536   ParallelTaskTerminator* terminator()     { return _terminator; }
4537 
4538 public:
4539   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4540                                 G1ParScanThreadState* par_scan_state,
4541                                 RefToScanQueueSet* queues,
4542                                 ParallelTaskTerminator* terminator)
4543     : _g1h(g1h), _par_scan_state(par_scan_state),
4544       _queues(queues), _terminator(terminator) {}
4545 
4546   void do_void();
4547 
4548 private:
4549   inline bool offer_termination();
4550 };
4551 
4552 bool G1ParEvacuateFollowersClosure::offer_termination() {
4553   G1ParScanThreadState* const pss = par_scan_state();
4554   pss->start_term_time();
4555   const bool res = terminator()->offer_termination();
4556   pss->end_term_time();
4557   return res;
4558 }
4559 
4560 void G1ParEvacuateFollowersClosure::do_void() {
4561   G1ParScanThreadState* const pss = par_scan_state();
4562   pss->trim_queue();
4563   do {
4564     pss->steal_and_trim_queue(queues());
4565   } while (!offer_termination());
4566 }
4567 
4568 class G1KlassScanClosure : public KlassClosure {
4569  G1ParCopyHelper* _closure;
4570  bool             _process_only_dirty;
4571  int              _count;
4572  public:
4573   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4574       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4575   void do_klass(Klass* klass) {
4576     // If the klass has not been dirtied we know that there's
4577     // no references into  the young gen and we can skip it.
4578    if (!_process_only_dirty || klass->has_modified_oops()) {
4579       // Clean the klass since we're going to scavenge all the metadata.
4580       klass->clear_modified_oops();
4581 
4582       // Tell the closure that this klass is the Klass to scavenge
4583       // and is the one to dirty if oops are left pointing into the young gen.
4584       _closure->set_scanned_klass(klass);
4585 
4586       klass->oops_do(_closure);
4587 
4588       _closure->set_scanned_klass(NULL);
4589     }
4590     _count++;
4591   }
4592 };
4593 
4594 class G1ParTask : public AbstractGangTask {
4595 protected:
4596   G1CollectedHeap*       _g1h;
4597   RefToScanQueueSet      *_queues;
4598   G1RootProcessor*       _root_processor;
4599   ParallelTaskTerminator _terminator;
4600   uint _n_workers;
4601 
4602   Mutex _stats_lock;
4603   Mutex* stats_lock() { return &_stats_lock; }
4604 
4605 public:
4606   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4607     : AbstractGangTask("G1 collection"),
4608       _g1h(g1h),
4609       _queues(task_queues),
4610       _root_processor(root_processor),
4611       _terminator(0, _queues),
4612       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4613   {}
4614 
4615   RefToScanQueueSet* queues() { return _queues; }
4616 
4617   RefToScanQueue *work_queue(int i) {
4618     return queues()->queue(i);
4619   }
4620 
4621   ParallelTaskTerminator* terminator() { return &_terminator; }
4622 
4623   virtual void set_for_termination(int active_workers) {
4624     _root_processor->set_num_workers(active_workers);
4625     terminator()->reset_for_reuse(active_workers);
4626     _n_workers = active_workers;
4627   }
4628 
4629   // Helps out with CLD processing.
4630   //
4631   // During InitialMark we need to:
4632   // 1) Scavenge all CLDs for the young GC.
4633   // 2) Mark all objects directly reachable from strong CLDs.
4634   template <G1Mark do_mark_object>
4635   class G1CLDClosure : public CLDClosure {
4636     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4637     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4638     G1KlassScanClosure                                _klass_in_cld_closure;
4639     bool                                              _claim;
4640 
4641    public:
4642     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4643                  bool only_young, bool claim)
4644         : _oop_closure(oop_closure),
4645           _oop_in_klass_closure(oop_closure->g1(),
4646                                 oop_closure->pss(),
4647                                 oop_closure->rp()),
4648           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4649           _claim(claim) {
4650 
4651     }
4652 
4653     void do_cld(ClassLoaderData* cld) {
4654       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4655     }
4656   };
4657 
4658   void work(uint worker_id) {
4659     if (worker_id >= _n_workers) return;  // no work needed this round
4660 
4661     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4662 
4663     {
4664       ResourceMark rm;
4665       HandleMark   hm;
4666 
4667       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4668 
4669       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4670       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4671 
4672       pss.set_evac_failure_closure(&evac_failure_cl);
4673 
4674       bool only_young = _g1h->g1_policy()->gcs_are_young();
4675 
4676       // Non-IM young GC.
4677       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4678       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4679                                                                                only_young, // Only process dirty klasses.
4680                                                                                false);     // No need to claim CLDs.
4681       // IM young GC.
4682       //    Strong roots closures.
4683       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4684       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4685                                                                                false, // Process all klasses.
4686                                                                                true); // Need to claim CLDs.
4687       //    Weak roots closures.
4688       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4689       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4690                                                                                     false, // Process all klasses.
4691                                                                                     true); // Need to claim CLDs.
4692 
4693       OopClosure* strong_root_cl;
4694       OopClosure* weak_root_cl;
4695       CLDClosure* strong_cld_cl;
4696       CLDClosure* weak_cld_cl;
4697 
4698       bool trace_metadata = false;
4699 
4700       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4701         // We also need to mark copied objects.
4702         strong_root_cl = &scan_mark_root_cl;
4703         strong_cld_cl  = &scan_mark_cld_cl;
4704         if (ClassUnloadingWithConcurrentMark) {
4705           weak_root_cl = &scan_mark_weak_root_cl;
4706           weak_cld_cl  = &scan_mark_weak_cld_cl;
4707           trace_metadata = true;
4708         } else {
4709           weak_root_cl = &scan_mark_root_cl;
4710           weak_cld_cl  = &scan_mark_cld_cl;
4711         }
4712       } else {
4713         strong_root_cl = &scan_only_root_cl;
4714         weak_root_cl   = &scan_only_root_cl;
4715         strong_cld_cl  = &scan_only_cld_cl;
4716         weak_cld_cl    = &scan_only_cld_cl;
4717       }
4718 
4719       pss.start_strong_roots();
4720 
4721       _root_processor->evacuate_roots(strong_root_cl,
4722                                       weak_root_cl,
4723                                       strong_cld_cl,
4724                                       weak_cld_cl,
4725                                       trace_metadata,
4726                                       worker_id);
4727 
4728       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4729       _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4730                                             weak_root_cl,
4731                                             worker_id);
4732       pss.end_strong_roots();
4733 
4734       {
4735         double start = os::elapsedTime();
4736         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4737         evac.do_void();
4738         double elapsed_sec = os::elapsedTime() - start;
4739         double term_sec = pss.term_time();
4740         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4741         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4742         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4743       }
4744       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4745       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4746 
4747       if (ParallelGCVerbose) {
4748         MutexLocker x(stats_lock());
4749         pss.print_termination_stats(worker_id);
4750       }
4751 
4752       assert(pss.queue_is_empty(), "should be empty");
4753 
4754       // Close the inner scope so that the ResourceMark and HandleMark
4755       // destructors are executed here and are included as part of the
4756       // "GC Worker Time".
4757     }
4758     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4759   }
4760 };
4761 
4762 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4763 private:
4764   BoolObjectClosure* _is_alive;
4765   int _initial_string_table_size;
4766   int _initial_symbol_table_size;
4767 
4768   bool  _process_strings;
4769   int _strings_processed;
4770   int _strings_removed;
4771 
4772   bool  _process_symbols;
4773   int _symbols_processed;
4774   int _symbols_removed;
4775 
4776   bool _do_in_parallel;
4777 public:
4778   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4779     AbstractGangTask("String/Symbol Unlinking"),
4780     _is_alive(is_alive),
4781     _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4782     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4783     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4784 
4785     _initial_string_table_size = StringTable::the_table()->table_size();
4786     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4787     if (process_strings) {
4788       StringTable::clear_parallel_claimed_index();
4789     }
4790     if (process_symbols) {
4791       SymbolTable::clear_parallel_claimed_index();
4792     }
4793   }
4794 
4795   ~G1StringSymbolTableUnlinkTask() {
4796     guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4797               err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4798                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4799     guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4800               err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4801                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4802 
4803     if (G1TraceStringSymbolTableScrubbing) {
4804       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4805                              "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4806                              "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4807                              strings_processed(), strings_removed(),
4808                              symbols_processed(), symbols_removed());
4809     }
4810   }
4811 
4812   void work(uint worker_id) {
4813     if (_do_in_parallel) {
4814       int strings_processed = 0;
4815       int strings_removed = 0;
4816       int symbols_processed = 0;
4817       int symbols_removed = 0;
4818       if (_process_strings) {
4819         StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4820         Atomic::add(strings_processed, &_strings_processed);
4821         Atomic::add(strings_removed, &_strings_removed);
4822       }
4823       if (_process_symbols) {
4824         SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4825         Atomic::add(symbols_processed, &_symbols_processed);
4826         Atomic::add(symbols_removed, &_symbols_removed);
4827       }
4828     } else {
4829       if (_process_strings) {
4830         StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
4831       }
4832       if (_process_symbols) {
4833         SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
4834       }
4835     }
4836   }
4837 
4838   size_t strings_processed() const { return (size_t)_strings_processed; }
4839   size_t strings_removed()   const { return (size_t)_strings_removed; }
4840 
4841   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4842   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4843 };
4844 
4845 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4846 private:
4847   static Monitor* _lock;
4848 
4849   BoolObjectClosure* const _is_alive;
4850   const bool               _unloading_occurred;
4851   const uint               _num_workers;
4852 
4853   // Variables used to claim nmethods.
4854   nmethod* _first_nmethod;
4855   volatile nmethod* _claimed_nmethod;
4856 
4857   // The list of nmethods that need to be processed by the second pass.
4858   volatile nmethod* _postponed_list;
4859   volatile uint     _num_entered_barrier;
4860 
4861  public:
4862   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4863       _is_alive(is_alive),
4864       _unloading_occurred(unloading_occurred),
4865       _num_workers(num_workers),
4866       _first_nmethod(NULL),
4867       _claimed_nmethod(NULL),
4868       _postponed_list(NULL),
4869       _num_entered_barrier(0)
4870   {
4871     nmethod::increase_unloading_clock();
4872     _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
4873     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4874   }
4875 
4876   ~G1CodeCacheUnloadingTask() {
4877     CodeCache::verify_clean_inline_caches();
4878 
4879     CodeCache::set_needs_cache_clean(false);
4880     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4881 
4882     CodeCache::verify_icholder_relocations();
4883   }
4884 
4885  private:
4886   void add_to_postponed_list(nmethod* nm) {
4887       nmethod* old;
4888       do {
4889         old = (nmethod*)_postponed_list;
4890         nm->set_unloading_next(old);
4891       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4892   }
4893 
4894   void clean_nmethod(nmethod* nm) {
4895     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4896 
4897     if (postponed) {
4898       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4899       add_to_postponed_list(nm);
4900     }
4901 
4902     // Mark that this thread has been cleaned/unloaded.
4903     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4904     nm->set_unloading_clock(nmethod::global_unloading_clock());
4905   }
4906 
4907   void clean_nmethod_postponed(nmethod* nm) {
4908     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4909   }
4910 
4911   static const int MaxClaimNmethods = 16;
4912 
4913   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4914     nmethod* first;
4915     nmethod* last;
4916 
4917     do {
4918       *num_claimed_nmethods = 0;
4919 
4920       first = last = (nmethod*)_claimed_nmethod;
4921 
4922       if (first != NULL) {
4923         for (int i = 0; i < MaxClaimNmethods; i++) {
4924           last = CodeCache::alive_nmethod(CodeCache::next(last));
4925 
4926           if (last == NULL) {
4927             break;
4928           }
4929 
4930           claimed_nmethods[i] = last;
4931           (*num_claimed_nmethods)++;
4932         }
4933       }
4934 
4935     } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
4936   }
4937 
4938   nmethod* claim_postponed_nmethod() {
4939     nmethod* claim;
4940     nmethod* next;
4941 
4942     do {
4943       claim = (nmethod*)_postponed_list;
4944       if (claim == NULL) {
4945         return NULL;
4946       }
4947 
4948       next = claim->unloading_next();
4949 
4950     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4951 
4952     return claim;
4953   }
4954 
4955  public:
4956   // Mark that we're done with the first pass of nmethod cleaning.
4957   void barrier_mark(uint worker_id) {
4958     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4959     _num_entered_barrier++;
4960     if (_num_entered_barrier == _num_workers) {
4961       ml.notify_all();
4962     }
4963   }
4964 
4965   // See if we have to wait for the other workers to
4966   // finish their first-pass nmethod cleaning work.
4967   void barrier_wait(uint worker_id) {
4968     if (_num_entered_barrier < _num_workers) {
4969       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4970       while (_num_entered_barrier < _num_workers) {
4971           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4972       }
4973     }
4974   }
4975 
4976   // Cleaning and unloading of nmethods. Some work has to be postponed
4977   // to the second pass, when we know which nmethods survive.
4978   void work_first_pass(uint worker_id) {
4979     // The first nmethods is claimed by the first worker.
4980     if (worker_id == 0 && _first_nmethod != NULL) {
4981       clean_nmethod(_first_nmethod);
4982       _first_nmethod = NULL;
4983     }
4984 
4985     int num_claimed_nmethods;
4986     nmethod* claimed_nmethods[MaxClaimNmethods];
4987 
4988     while (true) {
4989       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4990 
4991       if (num_claimed_nmethods == 0) {
4992         break;
4993       }
4994 
4995       for (int i = 0; i < num_claimed_nmethods; i++) {
4996         clean_nmethod(claimed_nmethods[i]);
4997       }
4998     }
4999 
5000     // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
5001     // Need to retire the buffers now that this thread has stopped cleaning nmethods.
5002     MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
5003   }
5004 
5005   void work_second_pass(uint worker_id) {
5006     nmethod* nm;
5007     // Take care of postponed nmethods.
5008     while ((nm = claim_postponed_nmethod()) != NULL) {
5009       clean_nmethod_postponed(nm);
5010     }
5011   }
5012 };
5013 
5014 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5015 
5016 class G1KlassCleaningTask : public StackObj {
5017   BoolObjectClosure*                      _is_alive;
5018   volatile jint                           _clean_klass_tree_claimed;
5019   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5020 
5021  public:
5022   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5023       _is_alive(is_alive),
5024       _clean_klass_tree_claimed(0),
5025       _klass_iterator() {
5026   }
5027 
5028  private:
5029   bool claim_clean_klass_tree_task() {
5030     if (_clean_klass_tree_claimed) {
5031       return false;
5032     }
5033 
5034     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5035   }
5036 
5037   InstanceKlass* claim_next_klass() {
5038     Klass* klass;
5039     do {
5040       klass =_klass_iterator.next_klass();
5041     } while (klass != NULL && !klass->oop_is_instance());
5042 
5043     return (InstanceKlass*)klass;
5044   }
5045 
5046 public:
5047 
5048   void clean_klass(InstanceKlass* ik) {
5049     ik->clean_implementors_list(_is_alive);
5050     ik->clean_method_data(_is_alive);
5051 
5052     // G1 specific cleanup work that has
5053     // been moved here to be done in parallel.
5054     ik->clean_dependent_nmethods();
5055     if (JvmtiExport::has_redefined_a_class()) {
5056       InstanceKlass::purge_previous_versions(ik);
5057     }
5058   }
5059 
5060   void work() {
5061     ResourceMark rm;
5062 
5063     // One worker will clean the subklass/sibling klass tree.
5064     if (claim_clean_klass_tree_task()) {
5065       Klass::clean_subklass_tree(_is_alive);
5066     }
5067 
5068     // All workers will help cleaning the classes,
5069     InstanceKlass* klass;
5070     while ((klass = claim_next_klass()) != NULL) {
5071       clean_klass(klass);
5072     }
5073   }
5074 };
5075 
5076 // To minimize the remark pause times, the tasks below are done in parallel.
5077 class G1ParallelCleaningTask : public AbstractGangTask {
5078 private:
5079   G1StringSymbolTableUnlinkTask _string_symbol_task;
5080   G1CodeCacheUnloadingTask      _code_cache_task;
5081   G1KlassCleaningTask           _klass_cleaning_task;
5082 
5083 public:
5084   // The constructor is run in the VMThread.
5085   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5086       AbstractGangTask("Parallel Cleaning"),
5087       _string_symbol_task(is_alive, process_strings, process_symbols),
5088       _code_cache_task(num_workers, is_alive, unloading_occurred),
5089       _klass_cleaning_task(is_alive) {
5090   }
5091 
5092   void pre_work_verification() {
5093     // The VM Thread will have registered Metadata during the single-threaded phase of MetadataStackOnMark.
5094     assert(Thread::current()->is_VM_thread()
5095            || !MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5096   }
5097 
5098   void post_work_verification() {
5099     assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5100   }
5101 
5102   // The parallel work done by all worker threads.
5103   void work(uint worker_id) {
5104     pre_work_verification();
5105 
5106     // Do first pass of code cache cleaning.
5107     _code_cache_task.work_first_pass(worker_id);
5108 
5109     // Let the threads mark that the first pass is done.
5110     _code_cache_task.barrier_mark(worker_id);
5111 
5112     // Clean the Strings and Symbols.
5113     _string_symbol_task.work(worker_id);
5114 
5115     // Wait for all workers to finish the first code cache cleaning pass.
5116     _code_cache_task.barrier_wait(worker_id);
5117 
5118     // Do the second code cache cleaning work, which realize on
5119     // the liveness information gathered during the first pass.
5120     _code_cache_task.work_second_pass(worker_id);
5121 
5122     // Clean all klasses that were not unloaded.
5123     _klass_cleaning_task.work();
5124 
5125     post_work_verification();
5126   }
5127 };
5128 
5129 
5130 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5131                                         bool process_strings,
5132                                         bool process_symbols,
5133                                         bool class_unloading_occurred) {
5134   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5135                     workers()->active_workers() : 1);
5136 
5137   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5138                                         n_workers, class_unloading_occurred);
5139   if (G1CollectedHeap::use_parallel_gc_threads()) {
5140     set_par_threads(n_workers);
5141     workers()->run_task(&g1_unlink_task);
5142     set_par_threads(0);
5143   } else {
5144     g1_unlink_task.work(0);
5145   }
5146 }
5147 
5148 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5149                                                      bool process_strings, bool process_symbols) {
5150   {
5151     uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5152                      _g1h->workers()->active_workers() : 1);
5153     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5154     if (G1CollectedHeap::use_parallel_gc_threads()) {
5155       set_par_threads(n_workers);
5156       workers()->run_task(&g1_unlink_task);
5157       set_par_threads(0);
5158     } else {
5159       g1_unlink_task.work(0);
5160     }
5161   }
5162 
5163   if (G1StringDedup::is_enabled()) {
5164     G1StringDedup::unlink(is_alive);
5165   }
5166 }
5167 
5168 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5169  private:
5170   DirtyCardQueueSet* _queue;
5171  public:
5172   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5173 
5174   virtual void work(uint worker_id) {
5175     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5176     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5177 
5178     RedirtyLoggedCardTableEntryClosure cl;
5179     if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5180       _queue->par_apply_closure_to_all_completed_buffers(&cl);
5181     } else {
5182       _queue->apply_closure_to_all_completed_buffers(&cl);
5183     }
5184 
5185     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5186   }
5187 };
5188 
5189 void G1CollectedHeap::redirty_logged_cards() {
5190   double redirty_logged_cards_start = os::elapsedTime();
5191 
5192   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5193                    _g1h->workers()->active_workers() : 1);
5194 
5195   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5196   dirty_card_queue_set().reset_for_par_iteration();
5197   if (use_parallel_gc_threads()) {
5198     set_par_threads(n_workers);
5199     workers()->run_task(&redirty_task);
5200     set_par_threads(0);
5201   } else {
5202     redirty_task.work(0);
5203   }
5204 
5205   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5206   dcq.merge_bufferlists(&dirty_card_queue_set());
5207   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5208 
5209   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5210 }
5211 
5212 // Weak Reference Processing support
5213 
5214 // An always "is_alive" closure that is used to preserve referents.
5215 // If the object is non-null then it's alive.  Used in the preservation
5216 // of referent objects that are pointed to by reference objects
5217 // discovered by the CM ref processor.
5218 class G1AlwaysAliveClosure: public BoolObjectClosure {
5219   G1CollectedHeap* _g1;
5220 public:
5221   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5222   bool do_object_b(oop p) {
5223     if (p != NULL) {
5224       return true;
5225     }
5226     return false;
5227   }
5228 };
5229 
5230 bool G1STWIsAliveClosure::do_object_b(oop p) {
5231   // An object is reachable if it is outside the collection set,
5232   // or is inside and copied.
5233   return !_g1->obj_in_cs(p) || p->is_forwarded();
5234 }
5235 
5236 // Non Copying Keep Alive closure
5237 class G1KeepAliveClosure: public OopClosure {
5238   G1CollectedHeap* _g1;
5239 public:
5240   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5241   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5242   void do_oop(oop* p) {
5243     oop obj = *p;
5244     assert(obj != NULL, "the caller should have filtered out NULL values");
5245 
5246     const InCSetState cset_state = _g1->in_cset_state(obj);
5247     if (!cset_state.is_in_cset_or_humongous()) {
5248       return;
5249     }
5250     if (cset_state.is_in_cset()) {
5251       assert( obj->is_forwarded(), "invariant" );
5252       *p = obj->forwardee();
5253     } else {
5254       assert(!obj->is_forwarded(), "invariant" );
5255       assert(cset_state.is_humongous(),
5256              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5257       _g1->set_humongous_is_live(obj);
5258     }
5259   }
5260 };
5261 
5262 // Copying Keep Alive closure - can be called from both
5263 // serial and parallel code as long as different worker
5264 // threads utilize different G1ParScanThreadState instances
5265 // and different queues.
5266 
5267 class G1CopyingKeepAliveClosure: public OopClosure {
5268   G1CollectedHeap*         _g1h;
5269   OopClosure*              _copy_non_heap_obj_cl;
5270   G1ParScanThreadState*    _par_scan_state;
5271 
5272 public:
5273   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5274                             OopClosure* non_heap_obj_cl,
5275                             G1ParScanThreadState* pss):
5276     _g1h(g1h),
5277     _copy_non_heap_obj_cl(non_heap_obj_cl),
5278     _par_scan_state(pss)
5279   {}
5280 
5281   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5282   virtual void do_oop(      oop* p) { do_oop_work(p); }
5283 
5284   template <class T> void do_oop_work(T* p) {
5285     oop obj = oopDesc::load_decode_heap_oop(p);
5286 
5287     if (_g1h->is_in_cset_or_humongous(obj)) {
5288       // If the referent object has been forwarded (either copied
5289       // to a new location or to itself in the event of an
5290       // evacuation failure) then we need to update the reference
5291       // field and, if both reference and referent are in the G1
5292       // heap, update the RSet for the referent.
5293       //
5294       // If the referent has not been forwarded then we have to keep
5295       // it alive by policy. Therefore we have copy the referent.
5296       //
5297       // If the reference field is in the G1 heap then we can push
5298       // on the PSS queue. When the queue is drained (after each
5299       // phase of reference processing) the object and it's followers
5300       // will be copied, the reference field set to point to the
5301       // new location, and the RSet updated. Otherwise we need to
5302       // use the the non-heap or metadata closures directly to copy
5303       // the referent object and update the pointer, while avoiding
5304       // updating the RSet.
5305 
5306       if (_g1h->is_in_g1_reserved(p)) {
5307         _par_scan_state->push_on_queue(p);
5308       } else {
5309         assert(!Metaspace::contains((const void*)p),
5310                err_msg("Unexpectedly found a pointer from metadata: "
5311                               PTR_FORMAT, p));
5312         _copy_non_heap_obj_cl->do_oop(p);
5313       }
5314     }
5315   }
5316 };
5317 
5318 // Serial drain queue closure. Called as the 'complete_gc'
5319 // closure for each discovered list in some of the
5320 // reference processing phases.
5321 
5322 class G1STWDrainQueueClosure: public VoidClosure {
5323 protected:
5324   G1CollectedHeap* _g1h;
5325   G1ParScanThreadState* _par_scan_state;
5326 
5327   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5328 
5329 public:
5330   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5331     _g1h(g1h),
5332     _par_scan_state(pss)
5333   { }
5334 
5335   void do_void() {
5336     G1ParScanThreadState* const pss = par_scan_state();
5337     pss->trim_queue();
5338   }
5339 };
5340 
5341 // Parallel Reference Processing closures
5342 
5343 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5344 // processing during G1 evacuation pauses.
5345 
5346 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5347 private:
5348   G1CollectedHeap*   _g1h;
5349   RefToScanQueueSet* _queues;
5350   FlexibleWorkGang*  _workers;
5351   int                _active_workers;
5352 
5353 public:
5354   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5355                         FlexibleWorkGang* workers,
5356                         RefToScanQueueSet *task_queues,
5357                         int n_workers) :
5358     _g1h(g1h),
5359     _queues(task_queues),
5360     _workers(workers),
5361     _active_workers(n_workers)
5362   {
5363     assert(n_workers > 0, "shouldn't call this otherwise");
5364   }
5365 
5366   // Executes the given task using concurrent marking worker threads.
5367   virtual void execute(ProcessTask& task);
5368   virtual void execute(EnqueueTask& task);
5369 };
5370 
5371 // Gang task for possibly parallel reference processing
5372 
5373 class G1STWRefProcTaskProxy: public AbstractGangTask {
5374   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5375   ProcessTask&     _proc_task;
5376   G1CollectedHeap* _g1h;
5377   RefToScanQueueSet *_task_queues;
5378   ParallelTaskTerminator* _terminator;
5379 
5380 public:
5381   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5382                      G1CollectedHeap* g1h,
5383                      RefToScanQueueSet *task_queues,
5384                      ParallelTaskTerminator* terminator) :
5385     AbstractGangTask("Process reference objects in parallel"),
5386     _proc_task(proc_task),
5387     _g1h(g1h),
5388     _task_queues(task_queues),
5389     _terminator(terminator)
5390   {}
5391 
5392   virtual void work(uint worker_id) {
5393     // The reference processing task executed by a single worker.
5394     ResourceMark rm;
5395     HandleMark   hm;
5396 
5397     G1STWIsAliveClosure is_alive(_g1h);
5398 
5399     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5400     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5401 
5402     pss.set_evac_failure_closure(&evac_failure_cl);
5403 
5404     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5405 
5406     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5407 
5408     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5409 
5410     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5411       // We also need to mark copied objects.
5412       copy_non_heap_cl = &copy_mark_non_heap_cl;
5413     }
5414 
5415     // Keep alive closure.
5416     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5417 
5418     // Complete GC closure
5419     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5420 
5421     // Call the reference processing task's work routine.
5422     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5423 
5424     // Note we cannot assert that the refs array is empty here as not all
5425     // of the processing tasks (specifically phase2 - pp2_work) execute
5426     // the complete_gc closure (which ordinarily would drain the queue) so
5427     // the queue may not be empty.
5428   }
5429 };
5430 
5431 // Driver routine for parallel reference processing.
5432 // Creates an instance of the ref processing gang
5433 // task and has the worker threads execute it.
5434 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5435   assert(_workers != NULL, "Need parallel worker threads.");
5436 
5437   ParallelTaskTerminator terminator(_active_workers, _queues);
5438   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5439 
5440   _g1h->set_par_threads(_active_workers);
5441   _workers->run_task(&proc_task_proxy);
5442   _g1h->set_par_threads(0);
5443 }
5444 
5445 // Gang task for parallel reference enqueueing.
5446 
5447 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5448   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5449   EnqueueTask& _enq_task;
5450 
5451 public:
5452   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5453     AbstractGangTask("Enqueue reference objects in parallel"),
5454     _enq_task(enq_task)
5455   { }
5456 
5457   virtual void work(uint worker_id) {
5458     _enq_task.work(worker_id);
5459   }
5460 };
5461 
5462 // Driver routine for parallel reference enqueueing.
5463 // Creates an instance of the ref enqueueing gang
5464 // task and has the worker threads execute it.
5465 
5466 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5467   assert(_workers != NULL, "Need parallel worker threads.");
5468 
5469   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5470 
5471   _g1h->set_par_threads(_active_workers);
5472   _workers->run_task(&enq_task_proxy);
5473   _g1h->set_par_threads(0);
5474 }
5475 
5476 // End of weak reference support closures
5477 
5478 // Abstract task used to preserve (i.e. copy) any referent objects
5479 // that are in the collection set and are pointed to by reference
5480 // objects discovered by the CM ref processor.
5481 
5482 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5483 protected:
5484   G1CollectedHeap* _g1h;
5485   RefToScanQueueSet      *_queues;
5486   ParallelTaskTerminator _terminator;
5487   uint _n_workers;
5488 
5489 public:
5490   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5491     AbstractGangTask("ParPreserveCMReferents"),
5492     _g1h(g1h),
5493     _queues(task_queues),
5494     _terminator(workers, _queues),
5495     _n_workers(workers)
5496   { }
5497 
5498   void work(uint worker_id) {
5499     ResourceMark rm;
5500     HandleMark   hm;
5501 
5502     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5503     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5504 
5505     pss.set_evac_failure_closure(&evac_failure_cl);
5506 
5507     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5508 
5509     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5510 
5511     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5512 
5513     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5514 
5515     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5516       // We also need to mark copied objects.
5517       copy_non_heap_cl = &copy_mark_non_heap_cl;
5518     }
5519 
5520     // Is alive closure
5521     G1AlwaysAliveClosure always_alive(_g1h);
5522 
5523     // Copying keep alive closure. Applied to referent objects that need
5524     // to be copied.
5525     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5526 
5527     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5528 
5529     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5530     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5531 
5532     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5533     // So this must be true - but assert just in case someone decides to
5534     // change the worker ids.
5535     assert(0 <= worker_id && worker_id < limit, "sanity");
5536     assert(!rp->discovery_is_atomic(), "check this code");
5537 
5538     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5539     for (uint idx = worker_id; idx < limit; idx += stride) {
5540       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5541 
5542       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5543       while (iter.has_next()) {
5544         // Since discovery is not atomic for the CM ref processor, we
5545         // can see some null referent objects.
5546         iter.load_ptrs(DEBUG_ONLY(true));
5547         oop ref = iter.obj();
5548 
5549         // This will filter nulls.
5550         if (iter.is_referent_alive()) {
5551           iter.make_referent_alive();
5552         }
5553         iter.move_to_next();
5554       }
5555     }
5556 
5557     // Drain the queue - which may cause stealing
5558     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5559     drain_queue.do_void();
5560     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5561     assert(pss.queue_is_empty(), "should be");
5562   }
5563 };
5564 
5565 // Weak Reference processing during an evacuation pause (part 1).
5566 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5567   double ref_proc_start = os::elapsedTime();
5568 
5569   ReferenceProcessor* rp = _ref_processor_stw;
5570   assert(rp->discovery_enabled(), "should have been enabled");
5571 
5572   // Any reference objects, in the collection set, that were 'discovered'
5573   // by the CM ref processor should have already been copied (either by
5574   // applying the external root copy closure to the discovered lists, or
5575   // by following an RSet entry).
5576   //
5577   // But some of the referents, that are in the collection set, that these
5578   // reference objects point to may not have been copied: the STW ref
5579   // processor would have seen that the reference object had already
5580   // been 'discovered' and would have skipped discovering the reference,
5581   // but would not have treated the reference object as a regular oop.
5582   // As a result the copy closure would not have been applied to the
5583   // referent object.
5584   //
5585   // We need to explicitly copy these referent objects - the references
5586   // will be processed at the end of remarking.
5587   //
5588   // We also need to do this copying before we process the reference
5589   // objects discovered by the STW ref processor in case one of these
5590   // referents points to another object which is also referenced by an
5591   // object discovered by the STW ref processor.
5592 
5593   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5594            no_of_gc_workers == workers()->active_workers(),
5595            "Need to reset active GC workers");
5596 
5597   set_par_threads(no_of_gc_workers);
5598   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5599                                                  no_of_gc_workers,
5600                                                  _task_queues);
5601 
5602   if (G1CollectedHeap::use_parallel_gc_threads()) {
5603     workers()->run_task(&keep_cm_referents);
5604   } else {
5605     keep_cm_referents.work(0);
5606   }
5607 
5608   set_par_threads(0);
5609 
5610   // Closure to test whether a referent is alive.
5611   G1STWIsAliveClosure is_alive(this);
5612 
5613   // Even when parallel reference processing is enabled, the processing
5614   // of JNI refs is serial and performed serially by the current thread
5615   // rather than by a worker. The following PSS will be used for processing
5616   // JNI refs.
5617 
5618   // Use only a single queue for this PSS.
5619   G1ParScanThreadState            pss(this, 0, NULL);
5620 
5621   // We do not embed a reference processor in the copying/scanning
5622   // closures while we're actually processing the discovered
5623   // reference objects.
5624   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5625 
5626   pss.set_evac_failure_closure(&evac_failure_cl);
5627 
5628   assert(pss.queue_is_empty(), "pre-condition");
5629 
5630   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5631 
5632   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5633 
5634   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5635 
5636   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5637     // We also need to mark copied objects.
5638     copy_non_heap_cl = &copy_mark_non_heap_cl;
5639   }
5640 
5641   // Keep alive closure.
5642   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5643 
5644   // Serial Complete GC closure
5645   G1STWDrainQueueClosure drain_queue(this, &pss);
5646 
5647   // Setup the soft refs policy...
5648   rp->setup_policy(false);
5649 
5650   ReferenceProcessorStats stats;
5651   if (!rp->processing_is_mt()) {
5652     // Serial reference processing...
5653     stats = rp->process_discovered_references(&is_alive,
5654                                               &keep_alive,
5655                                               &drain_queue,
5656                                               NULL,
5657                                               _gc_timer_stw,
5658                                               _gc_tracer_stw->gc_id());
5659   } else {
5660     // Parallel reference processing
5661     assert(rp->num_q() == no_of_gc_workers, "sanity");
5662     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5663 
5664     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5665     stats = rp->process_discovered_references(&is_alive,
5666                                               &keep_alive,
5667                                               &drain_queue,
5668                                               &par_task_executor,
5669                                               _gc_timer_stw,
5670                                               _gc_tracer_stw->gc_id());
5671   }
5672 
5673   _gc_tracer_stw->report_gc_reference_stats(stats);
5674 
5675   // We have completed copying any necessary live referent objects.
5676   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5677 
5678   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5679   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5680 }
5681 
5682 // Weak Reference processing during an evacuation pause (part 2).
5683 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5684   double ref_enq_start = os::elapsedTime();
5685 
5686   ReferenceProcessor* rp = _ref_processor_stw;
5687   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5688 
5689   // Now enqueue any remaining on the discovered lists on to
5690   // the pending list.
5691   if (!rp->processing_is_mt()) {
5692     // Serial reference processing...
5693     rp->enqueue_discovered_references();
5694   } else {
5695     // Parallel reference enqueueing
5696 
5697     assert(no_of_gc_workers == workers()->active_workers(),
5698            "Need to reset active workers");
5699     assert(rp->num_q() == no_of_gc_workers, "sanity");
5700     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5701 
5702     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5703     rp->enqueue_discovered_references(&par_task_executor);
5704   }
5705 
5706   rp->verify_no_references_recorded();
5707   assert(!rp->discovery_enabled(), "should have been disabled");
5708 
5709   // FIXME
5710   // CM's reference processing also cleans up the string and symbol tables.
5711   // Should we do that here also? We could, but it is a serial operation
5712   // and could significantly increase the pause time.
5713 
5714   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5715   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5716 }
5717 
5718 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5719   _expand_heap_after_alloc_failure = true;
5720   _evacuation_failed = false;
5721 
5722   // Should G1EvacuationFailureALot be in effect for this GC?
5723   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5724 
5725   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5726 
5727   // Disable the hot card cache.
5728   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5729   hot_card_cache->reset_hot_cache_claimed_index();
5730   hot_card_cache->set_use_cache(false);
5731 
5732   uint n_workers;
5733   if (G1CollectedHeap::use_parallel_gc_threads()) {
5734     n_workers =
5735       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5736                                      workers()->active_workers(),
5737                                      Threads::number_of_non_daemon_threads());
5738     assert(UseDynamicNumberOfGCThreads ||
5739            n_workers == workers()->total_workers(),
5740            "If not dynamic should be using all the  workers");
5741     workers()->set_active_workers(n_workers);
5742     set_par_threads(n_workers);
5743   } else {
5744     assert(n_par_threads() == 0,
5745            "Should be the original non-parallel value");
5746     n_workers = 1;
5747   }
5748 
5749 
5750   init_for_evac_failure(NULL);
5751 
5752   rem_set()->prepare_for_younger_refs_iterate(true);
5753 
5754   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5755   double start_par_time_sec = os::elapsedTime();
5756   double end_par_time_sec;
5757 
5758   {
5759     G1RootProcessor root_processor(this);
5760     G1ParTask g1_par_task(this, _task_queues, &root_processor);
5761     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5762     if (g1_policy()->during_initial_mark_pause()) {
5763       ClassLoaderDataGraph::clear_claimed_marks();
5764     }
5765 
5766     if (G1CollectedHeap::use_parallel_gc_threads()) {
5767       // The individual threads will set their evac-failure closures.
5768       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5769       // These tasks use ShareHeap::_process_strong_tasks
5770       assert(UseDynamicNumberOfGCThreads ||
5771              workers()->active_workers() == workers()->total_workers(),
5772              "If not dynamic should be using all the  workers");
5773       workers()->run_task(&g1_par_task);
5774     } else {
5775       g1_par_task.set_for_termination(n_workers);
5776       g1_par_task.work(0);
5777     }
5778     end_par_time_sec = os::elapsedTime();
5779 
5780     // Closing the inner scope will execute the destructor
5781     // for the G1RootProcessor object. We record the current
5782     // elapsed time before closing the scope so that time
5783     // taken for the destructor is NOT included in the
5784     // reported parallel time.
5785   }
5786 
5787   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5788 
5789   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5790   phase_times->record_par_time(par_time_ms);
5791 
5792   double code_root_fixup_time_ms =
5793         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5794   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5795 
5796   set_par_threads(0);
5797 
5798   // Process any discovered reference objects - we have
5799   // to do this _before_ we retire the GC alloc regions
5800   // as we may have to copy some 'reachable' referent
5801   // objects (and their reachable sub-graphs) that were
5802   // not copied during the pause.
5803   process_discovered_references(n_workers);
5804 
5805   if (G1StringDedup::is_enabled()) {
5806     double fixup_start = os::elapsedTime();
5807 
5808     G1STWIsAliveClosure is_alive(this);
5809     G1KeepAliveClosure keep_alive(this);
5810     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5811 
5812     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5813     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5814   }
5815 
5816   _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5817   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5818 
5819   // Reset and re-enable the hot card cache.
5820   // Note the counts for the cards in the regions in the
5821   // collection set are reset when the collection set is freed.
5822   hot_card_cache->reset_hot_cache();
5823   hot_card_cache->set_use_cache(true);
5824 
5825   purge_code_root_memory();
5826 
5827   if (g1_policy()->during_initial_mark_pause()) {
5828     // Reset the claim values set during marking the strong code roots
5829     reset_heap_region_claim_values();
5830   }
5831 
5832   finalize_for_evac_failure();
5833 
5834   if (evacuation_failed()) {
5835     remove_self_forwarding_pointers();
5836 
5837     // Reset the G1EvacuationFailureALot counters and flags
5838     // Note: the values are reset only when an actual
5839     // evacuation failure occurs.
5840     NOT_PRODUCT(reset_evacuation_should_fail();)
5841   }
5842 
5843   // Enqueue any remaining references remaining on the STW
5844   // reference processor's discovered lists. We need to do
5845   // this after the card table is cleaned (and verified) as
5846   // the act of enqueueing entries on to the pending list
5847   // will log these updates (and dirty their associated
5848   // cards). We need these updates logged to update any
5849   // RSets.
5850   enqueue_discovered_references(n_workers);
5851 
5852   redirty_logged_cards();
5853   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5854 }
5855 
5856 void G1CollectedHeap::free_region(HeapRegion* hr,
5857                                   FreeRegionList* free_list,
5858                                   bool par,
5859                                   bool locked) {
5860   assert(!hr->is_free(), "the region should not be free");
5861   assert(!hr->is_empty(), "the region should not be empty");
5862   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5863   assert(free_list != NULL, "pre-condition");
5864 
5865   if (G1VerifyBitmaps) {
5866     MemRegion mr(hr->bottom(), hr->end());
5867     concurrent_mark()->clearRangePrevBitmap(mr);
5868   }
5869 
5870   // Clear the card counts for this region.
5871   // Note: we only need to do this if the region is not young
5872   // (since we don't refine cards in young regions).
5873   if (!hr->is_young()) {
5874     _cg1r->hot_card_cache()->reset_card_counts(hr);
5875   }
5876   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5877   free_list->add_ordered(hr);
5878 }
5879 
5880 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5881                                      FreeRegionList* free_list,
5882                                      bool par) {
5883   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5884   assert(free_list != NULL, "pre-condition");
5885 
5886   size_t hr_capacity = hr->capacity();
5887   // We need to read this before we make the region non-humongous,
5888   // otherwise the information will be gone.
5889   uint last_index = hr->last_hc_index();
5890   hr->clear_humongous();
5891   free_region(hr, free_list, par);
5892 
5893   uint i = hr->hrm_index() + 1;
5894   while (i < last_index) {
5895     HeapRegion* curr_hr = region_at(i);
5896     assert(curr_hr->continuesHumongous(), "invariant");
5897     curr_hr->clear_humongous();
5898     free_region(curr_hr, free_list, par);
5899     i += 1;
5900   }
5901 }
5902 
5903 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5904                                        const HeapRegionSetCount& humongous_regions_removed) {
5905   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5906     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5907     _old_set.bulk_remove(old_regions_removed);
5908     _humongous_set.bulk_remove(humongous_regions_removed);
5909   }
5910 
5911 }
5912 
5913 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5914   assert(list != NULL, "list can't be null");
5915   if (!list->is_empty()) {
5916     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5917     _hrm.insert_list_into_free_list(list);
5918   }
5919 }
5920 
5921 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5922   _allocator->decrease_used(bytes);
5923 }
5924 
5925 class G1ParCleanupCTTask : public AbstractGangTask {
5926   G1SATBCardTableModRefBS* _ct_bs;
5927   G1CollectedHeap* _g1h;
5928   HeapRegion* volatile _su_head;
5929 public:
5930   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5931                      G1CollectedHeap* g1h) :
5932     AbstractGangTask("G1 Par Cleanup CT Task"),
5933     _ct_bs(ct_bs), _g1h(g1h) { }
5934 
5935   void work(uint worker_id) {
5936     HeapRegion* r;
5937     while (r = _g1h->pop_dirty_cards_region()) {
5938       clear_cards(r);
5939     }
5940   }
5941 
5942   void clear_cards(HeapRegion* r) {
5943     // Cards of the survivors should have already been dirtied.
5944     if (!r->is_survivor()) {
5945       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5946     }
5947   }
5948 };
5949 
5950 #ifndef PRODUCT
5951 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5952   G1CollectedHeap* _g1h;
5953   G1SATBCardTableModRefBS* _ct_bs;
5954 public:
5955   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5956     : _g1h(g1h), _ct_bs(ct_bs) { }
5957   virtual bool doHeapRegion(HeapRegion* r) {
5958     if (r->is_survivor()) {
5959       _g1h->verify_dirty_region(r);
5960     } else {
5961       _g1h->verify_not_dirty_region(r);
5962     }
5963     return false;
5964   }
5965 };
5966 
5967 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5968   // All of the region should be clean.
5969   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5970   MemRegion mr(hr->bottom(), hr->end());
5971   ct_bs->verify_not_dirty_region(mr);
5972 }
5973 
5974 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5975   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5976   // dirty allocated blocks as they allocate them. The thread that
5977   // retires each region and replaces it with a new one will do a
5978   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5979   // not dirty that area (one less thing to have to do while holding
5980   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5981   // is dirty.
5982   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5983   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5984   if (hr->is_young()) {
5985     ct_bs->verify_g1_young_region(mr);
5986   } else {
5987     ct_bs->verify_dirty_region(mr);
5988   }
5989 }
5990 
5991 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5992   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5993   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5994     verify_dirty_region(hr);
5995   }
5996 }
5997 
5998 void G1CollectedHeap::verify_dirty_young_regions() {
5999   verify_dirty_young_list(_young_list->first_region());
6000 }
6001 
6002 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6003                                                HeapWord* tams, HeapWord* end) {
6004   guarantee(tams <= end,
6005             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6006   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6007   if (result < end) {
6008     gclog_or_tty->cr();
6009     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6010                            bitmap_name, result);
6011     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6012                            bitmap_name, tams, end);
6013     return false;
6014   }
6015   return true;
6016 }
6017 
6018 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6019   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6020   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6021 
6022   HeapWord* bottom = hr->bottom();
6023   HeapWord* ptams  = hr->prev_top_at_mark_start();
6024   HeapWord* ntams  = hr->next_top_at_mark_start();
6025   HeapWord* end    = hr->end();
6026 
6027   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6028 
6029   bool res_n = true;
6030   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6031   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6032   // if we happen to be in that state.
6033   if (mark_in_progress() || !_cmThread->in_progress()) {
6034     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6035   }
6036   if (!res_p || !res_n) {
6037     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6038                            HR_FORMAT_PARAMS(hr));
6039     gclog_or_tty->print_cr("#### Caller: %s", caller);
6040     return false;
6041   }
6042   return true;
6043 }
6044 
6045 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6046   if (!G1VerifyBitmaps) return;
6047 
6048   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6049 }
6050 
6051 class G1VerifyBitmapClosure : public HeapRegionClosure {
6052 private:
6053   const char* _caller;
6054   G1CollectedHeap* _g1h;
6055   bool _failures;
6056 
6057 public:
6058   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6059     _caller(caller), _g1h(g1h), _failures(false) { }
6060 
6061   bool failures() { return _failures; }
6062 
6063   virtual bool doHeapRegion(HeapRegion* hr) {
6064     if (hr->continuesHumongous()) return false;
6065 
6066     bool result = _g1h->verify_bitmaps(_caller, hr);
6067     if (!result) {
6068       _failures = true;
6069     }
6070     return false;
6071   }
6072 };
6073 
6074 void G1CollectedHeap::check_bitmaps(const char* caller) {
6075   if (!G1VerifyBitmaps) return;
6076 
6077   G1VerifyBitmapClosure cl(caller, this);
6078   heap_region_iterate(&cl);
6079   guarantee(!cl.failures(), "bitmap verification");
6080 }
6081 
6082 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
6083  private:
6084   bool _failures;
6085  public:
6086   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
6087 
6088   virtual bool doHeapRegion(HeapRegion* hr) {
6089     uint i = hr->hrm_index();
6090     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
6091     if (hr->isHumongous()) {
6092       if (hr->in_collection_set()) {
6093         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
6094         _failures = true;
6095         return true;
6096       }
6097       if (cset_state.is_in_cset()) {
6098         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
6099         _failures = true;
6100         return true;
6101       }
6102       if (hr->continuesHumongous() && cset_state.is_humongous()) {
6103         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
6104         _failures = true;
6105         return true;
6106       }
6107     } else {
6108       if (cset_state.is_humongous()) {
6109         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
6110         _failures = true;
6111         return true;
6112       }
6113       if (hr->in_collection_set() != cset_state.is_in_cset()) {
6114         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6115                                hr->in_collection_set(), cset_state.value(), i);
6116        _failures = true;
6117        return true;
6118       }
6119       if (cset_state.is_in_cset()) {
6120         if (hr->is_young() != (cset_state.is_young())) {
6121           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6122                                  hr->is_young(), cset_state.value(), i);
6123           _failures = true;
6124           return true;
6125         }
6126         if (hr->is_old() != (cset_state.is_old())) {
6127           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6128                                  hr->is_old(), cset_state.value(), i);
6129           _failures = true;
6130           return true;
6131         }
6132       }
6133     }
6134     return false;
6135   }
6136 
6137   bool failures() const { return _failures; }
6138 };
6139 
6140 bool G1CollectedHeap::check_cset_fast_test() {
6141   G1CheckCSetFastTableClosure cl;
6142   _hrm.iterate(&cl);
6143   return !cl.failures();
6144 }
6145 #endif // PRODUCT
6146 
6147 void G1CollectedHeap::cleanUpCardTable() {
6148   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6149   double start = os::elapsedTime();
6150 
6151   {
6152     // Iterate over the dirty cards region list.
6153     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6154 
6155     if (G1CollectedHeap::use_parallel_gc_threads()) {
6156       set_par_threads();
6157       workers()->run_task(&cleanup_task);
6158       set_par_threads(0);
6159     } else {
6160       while (_dirty_cards_region_list) {
6161         HeapRegion* r = _dirty_cards_region_list;
6162         cleanup_task.clear_cards(r);
6163         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6164         if (_dirty_cards_region_list == r) {
6165           // The last region.
6166           _dirty_cards_region_list = NULL;
6167         }
6168         r->set_next_dirty_cards_region(NULL);
6169       }
6170     }
6171 #ifndef PRODUCT
6172     if (G1VerifyCTCleanup || VerifyAfterGC) {
6173       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6174       heap_region_iterate(&cleanup_verifier);
6175     }
6176 #endif
6177   }
6178 
6179   double elapsed = os::elapsedTime() - start;
6180   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6181 }
6182 
6183 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6184   size_t pre_used = 0;
6185   FreeRegionList local_free_list("Local List for CSet Freeing");
6186 
6187   double young_time_ms     = 0.0;
6188   double non_young_time_ms = 0.0;
6189 
6190   // Since the collection set is a superset of the the young list,
6191   // all we need to do to clear the young list is clear its
6192   // head and length, and unlink any young regions in the code below
6193   _young_list->clear();
6194 
6195   G1CollectorPolicy* policy = g1_policy();
6196 
6197   double start_sec = os::elapsedTime();
6198   bool non_young = true;
6199 
6200   HeapRegion* cur = cs_head;
6201   int age_bound = -1;
6202   size_t rs_lengths = 0;
6203 
6204   while (cur != NULL) {
6205     assert(!is_on_master_free_list(cur), "sanity");
6206     if (non_young) {
6207       if (cur->is_young()) {
6208         double end_sec = os::elapsedTime();
6209         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6210         non_young_time_ms += elapsed_ms;
6211 
6212         start_sec = os::elapsedTime();
6213         non_young = false;
6214       }
6215     } else {
6216       if (!cur->is_young()) {
6217         double end_sec = os::elapsedTime();
6218         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6219         young_time_ms += elapsed_ms;
6220 
6221         start_sec = os::elapsedTime();
6222         non_young = true;
6223       }
6224     }
6225 
6226     rs_lengths += cur->rem_set()->occupied_locked();
6227 
6228     HeapRegion* next = cur->next_in_collection_set();
6229     assert(cur->in_collection_set(), "bad CS");
6230     cur->set_next_in_collection_set(NULL);
6231     cur->set_in_collection_set(false);
6232 
6233     if (cur->is_young()) {
6234       int index = cur->young_index_in_cset();
6235       assert(index != -1, "invariant");
6236       assert((uint) index < policy->young_cset_region_length(), "invariant");
6237       size_t words_survived = _surviving_young_words[index];
6238       cur->record_surv_words_in_group(words_survived);
6239 
6240       // At this point the we have 'popped' cur from the collection set
6241       // (linked via next_in_collection_set()) but it is still in the
6242       // young list (linked via next_young_region()). Clear the
6243       // _next_young_region field.
6244       cur->set_next_young_region(NULL);
6245     } else {
6246       int index = cur->young_index_in_cset();
6247       assert(index == -1, "invariant");
6248     }
6249 
6250     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6251             (!cur->is_young() && cur->young_index_in_cset() == -1),
6252             "invariant" );
6253 
6254     if (!cur->evacuation_failed()) {
6255       MemRegion used_mr = cur->used_region();
6256 
6257       // And the region is empty.
6258       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6259       pre_used += cur->used();
6260       free_region(cur, &local_free_list, false /* par */, true /* locked */);
6261     } else {
6262       cur->uninstall_surv_rate_group();
6263       if (cur->is_young()) {
6264         cur->set_young_index_in_cset(-1);
6265       }
6266       cur->set_evacuation_failed(false);
6267       // The region is now considered to be old.
6268       cur->set_old();
6269       _old_set.add(cur);
6270       evacuation_info.increment_collectionset_used_after(cur->used());
6271     }
6272     cur = next;
6273   }
6274 
6275   evacuation_info.set_regions_freed(local_free_list.length());
6276   policy->record_max_rs_lengths(rs_lengths);
6277   policy->cset_regions_freed();
6278 
6279   double end_sec = os::elapsedTime();
6280   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6281 
6282   if (non_young) {
6283     non_young_time_ms += elapsed_ms;
6284   } else {
6285     young_time_ms += elapsed_ms;
6286   }
6287 
6288   prepend_to_freelist(&local_free_list);
6289   decrement_summary_bytes(pre_used);
6290   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6291   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6292 }
6293 
6294 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6295  private:
6296   FreeRegionList* _free_region_list;
6297   HeapRegionSet* _proxy_set;
6298   HeapRegionSetCount _humongous_regions_removed;
6299   size_t _freed_bytes;
6300  public:
6301 
6302   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6303     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6304   }
6305 
6306   virtual bool doHeapRegion(HeapRegion* r) {
6307     if (!r->startsHumongous()) {
6308       return false;
6309     }
6310 
6311     G1CollectedHeap* g1h = G1CollectedHeap::heap();
6312 
6313     oop obj = (oop)r->bottom();
6314     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6315 
6316     // The following checks whether the humongous object is live are sufficient.
6317     // The main additional check (in addition to having a reference from the roots
6318     // or the young gen) is whether the humongous object has a remembered set entry.
6319     //
6320     // A humongous object cannot be live if there is no remembered set for it
6321     // because:
6322     // - there can be no references from within humongous starts regions referencing
6323     // the object because we never allocate other objects into them.
6324     // (I.e. there are no intra-region references that may be missed by the
6325     // remembered set)
6326     // - as soon there is a remembered set entry to the humongous starts region
6327     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6328     // until the end of a concurrent mark.
6329     //
6330     // It is not required to check whether the object has been found dead by marking
6331     // or not, in fact it would prevent reclamation within a concurrent cycle, as
6332     // all objects allocated during that time are considered live.
6333     // SATB marking is even more conservative than the remembered set.
6334     // So if at this point in the collection there is no remembered set entry,
6335     // nobody has a reference to it.
6336     // At the start of collection we flush all refinement logs, and remembered sets
6337     // are completely up-to-date wrt to references to the humongous object.
6338     //
6339     // Other implementation considerations:
6340     // - never consider object arrays at this time because they would pose
6341     // considerable effort for cleaning up the the remembered sets. This is
6342     // required because stale remembered sets might reference locations that
6343     // are currently allocated into.
6344     uint region_idx = r->hrm_index();
6345     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6346         !r->rem_set()->is_empty()) {
6347 
6348       if (G1TraceEagerReclaimHumongousObjects) {
6349         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",
6350                                region_idx,
6351                                obj->size()*HeapWordSize,
6352                                r->bottom(),
6353                                r->region_num(),
6354                                r->rem_set()->occupied(),
6355                                r->rem_set()->strong_code_roots_list_length(),
6356                                next_bitmap->isMarked(r->bottom()),
6357                                g1h->is_humongous_reclaim_candidate(region_idx),
6358                                obj->is_typeArray()
6359                               );
6360       }
6361 
6362       return false;
6363     }
6364 
6365     guarantee(obj->is_typeArray(),
6366               err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6367                       PTR_FORMAT " is not.",
6368                       r->bottom()));
6369 
6370     if (G1TraceEagerReclaimHumongousObjects) {
6371       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",
6372                              region_idx,
6373                              obj->size()*HeapWordSize,
6374                              r->bottom(),
6375                              r->region_num(),
6376                              r->rem_set()->occupied(),
6377                              r->rem_set()->strong_code_roots_list_length(),
6378                              next_bitmap->isMarked(r->bottom()),
6379                              g1h->is_humongous_reclaim_candidate(region_idx),
6380                              obj->is_typeArray()
6381                             );
6382     }
6383     // Need to clear mark bit of the humongous object if already set.
6384     if (next_bitmap->isMarked(r->bottom())) {
6385       next_bitmap->clear(r->bottom());
6386     }
6387     _freed_bytes += r->used();
6388     r->set_containing_set(NULL);
6389     _humongous_regions_removed.increment(1u, r->capacity());
6390     g1h->free_humongous_region(r, _free_region_list, false);
6391 
6392     return false;
6393   }
6394 
6395   HeapRegionSetCount& humongous_free_count() {
6396     return _humongous_regions_removed;
6397   }
6398 
6399   size_t bytes_freed() const {
6400     return _freed_bytes;
6401   }
6402 
6403   size_t humongous_reclaimed() const {
6404     return _humongous_regions_removed.length();
6405   }
6406 };
6407 
6408 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6409   assert_at_safepoint(true);
6410 
6411   if (!G1EagerReclaimHumongousObjects ||
6412       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6413     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6414     return;
6415   }
6416 
6417   double start_time = os::elapsedTime();
6418 
6419   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6420 
6421   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6422   heap_region_iterate(&cl);
6423 
6424   HeapRegionSetCount empty_set;
6425   remove_from_old_sets(empty_set, cl.humongous_free_count());
6426 
6427   G1HRPrinter* hr_printer = _g1h->hr_printer();
6428   if (hr_printer->is_active()) {
6429     FreeRegionListIterator iter(&local_cleanup_list);
6430     while (iter.more_available()) {
6431       HeapRegion* hr = iter.get_next();
6432       hr_printer->cleanup(hr);
6433     }
6434   }
6435 
6436   prepend_to_freelist(&local_cleanup_list);
6437   decrement_summary_bytes(cl.bytes_freed());
6438 
6439   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6440                                                                     cl.humongous_reclaimed());
6441 }
6442 
6443 // This routine is similar to the above but does not record
6444 // any policy statistics or update free lists; we are abandoning
6445 // the current incremental collection set in preparation of a
6446 // full collection. After the full GC we will start to build up
6447 // the incremental collection set again.
6448 // This is only called when we're doing a full collection
6449 // and is immediately followed by the tearing down of the young list.
6450 
6451 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6452   HeapRegion* cur = cs_head;
6453 
6454   while (cur != NULL) {
6455     HeapRegion* next = cur->next_in_collection_set();
6456     assert(cur->in_collection_set(), "bad CS");
6457     cur->set_next_in_collection_set(NULL);
6458     cur->set_in_collection_set(false);
6459     cur->set_young_index_in_cset(-1);
6460     cur = next;
6461   }
6462 }
6463 
6464 void G1CollectedHeap::set_free_regions_coming() {
6465   if (G1ConcRegionFreeingVerbose) {
6466     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6467                            "setting free regions coming");
6468   }
6469 
6470   assert(!free_regions_coming(), "pre-condition");
6471   _free_regions_coming = true;
6472 }
6473 
6474 void G1CollectedHeap::reset_free_regions_coming() {
6475   assert(free_regions_coming(), "pre-condition");
6476 
6477   {
6478     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6479     _free_regions_coming = false;
6480     SecondaryFreeList_lock->notify_all();
6481   }
6482 
6483   if (G1ConcRegionFreeingVerbose) {
6484     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6485                            "reset free regions coming");
6486   }
6487 }
6488 
6489 void G1CollectedHeap::wait_while_free_regions_coming() {
6490   // Most of the time we won't have to wait, so let's do a quick test
6491   // first before we take the lock.
6492   if (!free_regions_coming()) {
6493     return;
6494   }
6495 
6496   if (G1ConcRegionFreeingVerbose) {
6497     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6498                            "waiting for free regions");
6499   }
6500 
6501   {
6502     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6503     while (free_regions_coming()) {
6504       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6505     }
6506   }
6507 
6508   if (G1ConcRegionFreeingVerbose) {
6509     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6510                            "done waiting for free regions");
6511   }
6512 }
6513 
6514 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6515   assert(heap_lock_held_for_gc(),
6516               "the heap lock should already be held by or for this thread");
6517   _young_list->push_region(hr);
6518 }
6519 
6520 class NoYoungRegionsClosure: public HeapRegionClosure {
6521 private:
6522   bool _success;
6523 public:
6524   NoYoungRegionsClosure() : _success(true) { }
6525   bool doHeapRegion(HeapRegion* r) {
6526     if (r->is_young()) {
6527       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6528                              r->bottom(), r->end());
6529       _success = false;
6530     }
6531     return false;
6532   }
6533   bool success() { return _success; }
6534 };
6535 
6536 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6537   bool ret = _young_list->check_list_empty(check_sample);
6538 
6539   if (check_heap) {
6540     NoYoungRegionsClosure closure;
6541     heap_region_iterate(&closure);
6542     ret = ret && closure.success();
6543   }
6544 
6545   return ret;
6546 }
6547 
6548 class TearDownRegionSetsClosure : public HeapRegionClosure {
6549 private:
6550   HeapRegionSet *_old_set;
6551 
6552 public:
6553   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6554 
6555   bool doHeapRegion(HeapRegion* r) {
6556     if (r->is_old()) {
6557       _old_set->remove(r);
6558     } else {
6559       // We ignore free regions, we'll empty the free list afterwards.
6560       // We ignore young regions, we'll empty the young list afterwards.
6561       // We ignore humongous regions, we're not tearing down the
6562       // humongous regions set.
6563       assert(r->is_free() || r->is_young() || r->isHumongous(),
6564              "it cannot be another type");
6565     }
6566     return false;
6567   }
6568 
6569   ~TearDownRegionSetsClosure() {
6570     assert(_old_set->is_empty(), "post-condition");
6571   }
6572 };
6573 
6574 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6575   assert_at_safepoint(true /* should_be_vm_thread */);
6576 
6577   if (!free_list_only) {
6578     TearDownRegionSetsClosure cl(&_old_set);
6579     heap_region_iterate(&cl);
6580 
6581     // Note that emptying the _young_list is postponed and instead done as
6582     // the first step when rebuilding the regions sets again. The reason for
6583     // this is that during a full GC string deduplication needs to know if
6584     // a collected region was young or old when the full GC was initiated.
6585   }
6586   _hrm.remove_all_free_regions();
6587 }
6588 
6589 class RebuildRegionSetsClosure : public HeapRegionClosure {
6590 private:
6591   bool            _free_list_only;
6592   HeapRegionSet*   _old_set;
6593   HeapRegionManager*   _hrm;
6594   size_t          _total_used;
6595 
6596 public:
6597   RebuildRegionSetsClosure(bool free_list_only,
6598                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6599     _free_list_only(free_list_only),
6600     _old_set(old_set), _hrm(hrm), _total_used(0) {
6601     assert(_hrm->num_free_regions() == 0, "pre-condition");
6602     if (!free_list_only) {
6603       assert(_old_set->is_empty(), "pre-condition");
6604     }
6605   }
6606 
6607   bool doHeapRegion(HeapRegion* r) {
6608     if (r->continuesHumongous()) {
6609       return false;
6610     }
6611 
6612     if (r->is_empty()) {
6613       // Add free regions to the free list
6614       r->set_free();
6615       r->set_allocation_context(AllocationContext::system());
6616       _hrm->insert_into_free_list(r);
6617     } else if (!_free_list_only) {
6618       assert(!r->is_young(), "we should not come across young regions");
6619 
6620       if (r->isHumongous()) {
6621         // We ignore humongous regions, we left the humongous set unchanged
6622       } else {
6623         // Objects that were compacted would have ended up on regions
6624         // that were previously old or free.
6625         assert(r->is_free() || r->is_old(), "invariant");
6626         // We now consider them old, so register as such.
6627         r->set_old();
6628         _old_set->add(r);
6629       }
6630       _total_used += r->used();
6631     }
6632 
6633     return false;
6634   }
6635 
6636   size_t total_used() {
6637     return _total_used;
6638   }
6639 };
6640 
6641 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6642   assert_at_safepoint(true /* should_be_vm_thread */);
6643 
6644   if (!free_list_only) {
6645     _young_list->empty_list();
6646   }
6647 
6648   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6649   heap_region_iterate(&cl);
6650 
6651   if (!free_list_only) {
6652     _allocator->set_used(cl.total_used());
6653   }
6654   assert(_allocator->used_unlocked() == recalculate_used(),
6655          err_msg("inconsistent _allocator->used_unlocked(), "
6656                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6657                  _allocator->used_unlocked(), recalculate_used()));
6658 }
6659 
6660 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6661   _refine_cte_cl->set_concurrent(concurrent);
6662 }
6663 
6664 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6665   HeapRegion* hr = heap_region_containing(p);
6666   return hr->is_in(p);
6667 }
6668 
6669 // Methods for the mutator alloc region
6670 
6671 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6672                                                       bool force) {
6673   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6674   assert(!force || g1_policy()->can_expand_young_list(),
6675          "if force is true we should be able to expand the young list");
6676   bool young_list_full = g1_policy()->is_young_list_full();
6677   if (force || !young_list_full) {
6678     HeapRegion* new_alloc_region = new_region(word_size,
6679                                               false /* is_old */,
6680                                               false /* do_expand */);
6681     if (new_alloc_region != NULL) {
6682       set_region_short_lived_locked(new_alloc_region);
6683       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6684       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6685       return new_alloc_region;
6686     }
6687   }
6688   return NULL;
6689 }
6690 
6691 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6692                                                   size_t allocated_bytes) {
6693   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6694   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6695 
6696   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6697   _allocator->increase_used(allocated_bytes);
6698   _hr_printer.retire(alloc_region);
6699   // We update the eden sizes here, when the region is retired,
6700   // instead of when it's allocated, since this is the point that its
6701   // used space has been recored in _summary_bytes_used.
6702   g1mm()->update_eden_size();
6703 }
6704 
6705 void G1CollectedHeap::set_par_threads() {
6706   // Don't change the number of workers.  Use the value previously set
6707   // in the workgroup.
6708   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6709   uint n_workers = workers()->active_workers();
6710   assert(UseDynamicNumberOfGCThreads ||
6711            n_workers == workers()->total_workers(),
6712       "Otherwise should be using the total number of workers");
6713   if (n_workers == 0) {
6714     assert(false, "Should have been set in prior evacuation pause.");
6715     n_workers = ParallelGCThreads;
6716     workers()->set_active_workers(n_workers);
6717   }
6718   set_par_threads(n_workers);
6719 }
6720 
6721 // Methods for the GC alloc regions
6722 
6723 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6724                                                  uint count,
6725                                                  InCSetState dest) {
6726   assert(FreeList_lock->owned_by_self(), "pre-condition");
6727 
6728   if (count < g1_policy()->max_regions(dest)) {
6729     const bool is_survivor = (dest.is_young());
6730     HeapRegion* new_alloc_region = new_region(word_size,
6731                                               !is_survivor,
6732                                               true /* do_expand */);
6733     if (new_alloc_region != NULL) {
6734       // We really only need to do this for old regions given that we
6735       // should never scan survivors. But it doesn't hurt to do it
6736       // for survivors too.
6737       new_alloc_region->record_timestamp();
6738       if (is_survivor) {
6739         new_alloc_region->set_survivor();
6740         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6741         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6742       } else {
6743         new_alloc_region->set_old();
6744         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6745         check_bitmaps("Old Region Allocation", new_alloc_region);
6746       }
6747       bool during_im = g1_policy()->during_initial_mark_pause();
6748       new_alloc_region->note_start_of_copying(during_im);
6749       return new_alloc_region;
6750     }
6751   }
6752   return NULL;
6753 }
6754 
6755 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6756                                              size_t allocated_bytes,
6757                                              InCSetState dest) {
6758   bool during_im = g1_policy()->during_initial_mark_pause();
6759   alloc_region->note_end_of_copying(during_im);
6760   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6761   if (dest.is_young()) {
6762     young_list()->add_survivor_region(alloc_region);
6763   } else {
6764     _old_set.add(alloc_region);
6765   }
6766   _hr_printer.retire(alloc_region);
6767 }
6768 
6769 // Heap region set verification
6770 
6771 class VerifyRegionListsClosure : public HeapRegionClosure {
6772 private:
6773   HeapRegionSet*   _old_set;
6774   HeapRegionSet*   _humongous_set;
6775   HeapRegionManager*   _hrm;
6776 
6777 public:
6778   HeapRegionSetCount _old_count;
6779   HeapRegionSetCount _humongous_count;
6780   HeapRegionSetCount _free_count;
6781 
6782   VerifyRegionListsClosure(HeapRegionSet* old_set,
6783                            HeapRegionSet* humongous_set,
6784                            HeapRegionManager* hrm) :
6785     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6786     _old_count(), _humongous_count(), _free_count(){ }
6787 
6788   bool doHeapRegion(HeapRegion* hr) {
6789     if (hr->continuesHumongous()) {
6790       return false;
6791     }
6792 
6793     if (hr->is_young()) {
6794       // TODO
6795     } else if (hr->startsHumongous()) {
6796       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6797       _humongous_count.increment(1u, hr->capacity());
6798     } else if (hr->is_empty()) {
6799       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6800       _free_count.increment(1u, hr->capacity());
6801     } else if (hr->is_old()) {
6802       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6803       _old_count.increment(1u, hr->capacity());
6804     } else {
6805       ShouldNotReachHere();
6806     }
6807     return false;
6808   }
6809 
6810   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6811     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6812     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6813         old_set->total_capacity_bytes(), _old_count.capacity()));
6814 
6815     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6816     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6817         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6818 
6819     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()));
6820     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6821         free_list->total_capacity_bytes(), _free_count.capacity()));
6822   }
6823 };
6824 
6825 void G1CollectedHeap::verify_region_sets() {
6826   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6827 
6828   // First, check the explicit lists.
6829   _hrm.verify();
6830   {
6831     // Given that a concurrent operation might be adding regions to
6832     // the secondary free list we have to take the lock before
6833     // verifying it.
6834     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6835     _secondary_free_list.verify_list();
6836   }
6837 
6838   // If a concurrent region freeing operation is in progress it will
6839   // be difficult to correctly attributed any free regions we come
6840   // across to the correct free list given that they might belong to
6841   // one of several (free_list, secondary_free_list, any local lists,
6842   // etc.). So, if that's the case we will skip the rest of the
6843   // verification operation. Alternatively, waiting for the concurrent
6844   // operation to complete will have a non-trivial effect on the GC's
6845   // operation (no concurrent operation will last longer than the
6846   // interval between two calls to verification) and it might hide
6847   // any issues that we would like to catch during testing.
6848   if (free_regions_coming()) {
6849     return;
6850   }
6851 
6852   // Make sure we append the secondary_free_list on the free_list so
6853   // that all free regions we will come across can be safely
6854   // attributed to the free_list.
6855   append_secondary_free_list_if_not_empty_with_lock();
6856 
6857   // Finally, make sure that the region accounting in the lists is
6858   // consistent with what we see in the heap.
6859 
6860   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6861   heap_region_iterate(&cl);
6862   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6863 }
6864 
6865 // Optimized nmethod scanning
6866 
6867 class RegisterNMethodOopClosure: public OopClosure {
6868   G1CollectedHeap* _g1h;
6869   nmethod* _nm;
6870 
6871   template <class T> void do_oop_work(T* p) {
6872     T heap_oop = oopDesc::load_heap_oop(p);
6873     if (!oopDesc::is_null(heap_oop)) {
6874       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6875       HeapRegion* hr = _g1h->heap_region_containing(obj);
6876       assert(!hr->continuesHumongous(),
6877              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6878                      " starting at "HR_FORMAT,
6879                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6880 
6881       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6882       hr->add_strong_code_root_locked(_nm);
6883     }
6884   }
6885 
6886 public:
6887   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6888     _g1h(g1h), _nm(nm) {}
6889 
6890   void do_oop(oop* p)       { do_oop_work(p); }
6891   void do_oop(narrowOop* p) { do_oop_work(p); }
6892 };
6893 
6894 class UnregisterNMethodOopClosure: 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 remove 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       hr->remove_strong_code_root(_nm);
6909     }
6910   }
6911 
6912 public:
6913   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6914     _g1h(g1h), _nm(nm) {}
6915 
6916   void do_oop(oop* p)       { do_oop_work(p); }
6917   void do_oop(narrowOop* p) { do_oop_work(p); }
6918 };
6919 
6920 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6921   CollectedHeap::register_nmethod(nm);
6922 
6923   guarantee(nm != NULL, "sanity");
6924   RegisterNMethodOopClosure reg_cl(this, nm);
6925   nm->oops_do(&reg_cl);
6926 }
6927 
6928 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6929   CollectedHeap::unregister_nmethod(nm);
6930 
6931   guarantee(nm != NULL, "sanity");
6932   UnregisterNMethodOopClosure reg_cl(this, nm);
6933   nm->oops_do(&reg_cl, true);
6934 }
6935 
6936 void G1CollectedHeap::purge_code_root_memory() {
6937   double purge_start = os::elapsedTime();
6938   G1CodeRootSet::purge();
6939   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6940   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6941 }
6942 
6943 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6944   G1CollectedHeap* _g1h;
6945 
6946 public:
6947   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6948     _g1h(g1h) {}
6949 
6950   void do_code_blob(CodeBlob* cb) {
6951     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6952     if (nm == NULL) {
6953       return;
6954     }
6955 
6956     if (ScavengeRootsInCode) {
6957       _g1h->register_nmethod(nm);
6958     }
6959   }
6960 };
6961 
6962 void G1CollectedHeap::rebuild_strong_code_roots() {
6963   RebuildStrongCodeRootClosure blob_cl(this);
6964   CodeCache::blobs_do(&blob_cl);
6965 }