1 /*
   2  * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "code/icBuffer.hpp"
  27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  34 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  35 #include "gc_implementation/g1/g1MarkSweep.hpp"
  36 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  37 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  38 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  39 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  40 #include "gc_implementation/g1/vm_operations_g1.hpp"
  41 #include "gc_implementation/shared/isGCActiveMark.hpp"
  42 #include "memory/gcLocker.inline.hpp"
  43 #include "memory/genOopClosures.inline.hpp"
  44 #include "memory/generationSpec.hpp"
  45 #include "memory/referenceProcessor.hpp"
  46 #include "oops/oop.inline.hpp"
  47 #include "oops/oop.pcgc.inline.hpp"
  48 #include "runtime/aprofiler.hpp"
  49 #include "runtime/vmThread.hpp"
  50 
  51 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  52 
  53 // turn it on so that the contents of the young list (scan-only /
  54 // to-be-collected) are printed at "strategic" points before / during
  55 // / after the collection --- this is useful for debugging
  56 #define YOUNG_LIST_VERBOSE 0
  57 // CURRENT STATUS
  58 // This file is under construction.  Search for "FIXME".
  59 
  60 // INVARIANTS/NOTES
  61 //
  62 // All allocation activity covered by the G1CollectedHeap interface is
  63 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  64 // and allocate_new_tlab, which are the "entry" points to the
  65 // allocation code from the rest of the JVM.  (Note that this does not
  66 // apply to TLAB allocation, which is not part of this interface: it
  67 // is done by clients of this interface.)
  68 
  69 // Local to this file.
  70 
  71 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  72   SuspendibleThreadSet* _sts;
  73   G1RemSet* _g1rs;
  74   ConcurrentG1Refine* _cg1r;
  75   bool _concurrent;
  76 public:
  77   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  78                               G1RemSet* g1rs,
  79                               ConcurrentG1Refine* cg1r) :
  80     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
  81   {}
  82   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
  83     bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
  84     // This path is executed by the concurrent refine or mutator threads,
  85     // concurrently, and so we do not care if card_ptr contains references
  86     // that point into the collection set.
  87     assert(!oops_into_cset, "should be");
  88 
  89     if (_concurrent && _sts->should_yield()) {
  90       // Caller will actually yield.
  91       return false;
  92     }
  93     // Otherwise, we finished successfully; return true.
  94     return true;
  95   }
  96   void set_concurrent(bool b) { _concurrent = b; }
  97 };
  98 
  99 
 100 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 101   int _calls;
 102   G1CollectedHeap* _g1h;
 103   CardTableModRefBS* _ctbs;
 104   int _histo[256];
 105 public:
 106   ClearLoggedCardTableEntryClosure() :
 107     _calls(0)
 108   {
 109     _g1h = G1CollectedHeap::heap();
 110     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 111     for (int i = 0; i < 256; i++) _histo[i] = 0;
 112   }
 113   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 114     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 115       _calls++;
 116       unsigned char* ujb = (unsigned char*)card_ptr;
 117       int ind = (int)(*ujb);
 118       _histo[ind]++;
 119       *card_ptr = -1;
 120     }
 121     return true;
 122   }
 123   int calls() { return _calls; }
 124   void print_histo() {
 125     gclog_or_tty->print_cr("Card table value histogram:");
 126     for (int i = 0; i < 256; i++) {
 127       if (_histo[i] != 0) {
 128         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 129       }
 130     }
 131   }
 132 };
 133 
 134 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 135   int _calls;
 136   G1CollectedHeap* _g1h;
 137   CardTableModRefBS* _ctbs;
 138 public:
 139   RedirtyLoggedCardTableEntryClosure() :
 140     _calls(0)
 141   {
 142     _g1h = G1CollectedHeap::heap();
 143     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 144   }
 145   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 146     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 147       _calls++;
 148       *card_ptr = 0;
 149     }
 150     return true;
 151   }
 152   int calls() { return _calls; }
 153 };
 154 
 155 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 156 public:
 157   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 158     *card_ptr = CardTableModRefBS::dirty_card_val();
 159     return true;
 160   }
 161 };
 162 
 163 YoungList::YoungList(G1CollectedHeap* g1h)
 164   : _g1h(g1h), _head(NULL),
 165     _length(0),
 166     _last_sampled_rs_lengths(0),
 167     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
 168 {
 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   hr->set_young();
 180   double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
 181   ++_length;
 182 }
 183 
 184 void YoungList::add_survivor_region(HeapRegion* hr) {
 185   assert(hr->is_survivor(), "should be flagged as survivor region");
 186   assert(hr->get_next_young_region() == NULL, "cause it should!");
 187 
 188   hr->set_next_young_region(_survivor_head);
 189   if (_survivor_head == NULL) {
 190     _survivor_tail = hr;
 191   }
 192   _survivor_head = hr;
 193 
 194   ++_survivor_length;
 195 }
 196 
 197 void YoungList::empty_list(HeapRegion* list) {
 198   while (list != NULL) {
 199     HeapRegion* next = list->get_next_young_region();
 200     list->set_next_young_region(NULL);
 201     list->uninstall_surv_rate_group();
 202     list->set_not_young();
 203     list = next;
 204   }
 205 }
 206 
 207 void YoungList::empty_list() {
 208   assert(check_list_well_formed(), "young list should be well formed");
 209 
 210   empty_list(_head);
 211   _head = NULL;
 212   _length = 0;
 213 
 214   empty_list(_survivor_head);
 215   _survivor_head = NULL;
 216   _survivor_tail = NULL;
 217   _survivor_length = 0;
 218 
 219   _last_sampled_rs_lengths = 0;
 220 
 221   assert(check_list_empty(false), "just making sure...");
 222 }
 223 
 224 bool YoungList::check_list_well_formed() {
 225   bool ret = true;
 226 
 227   size_t length = 0;
 228   HeapRegion* curr = _head;
 229   HeapRegion* last = NULL;
 230   while (curr != NULL) {
 231     if (!curr->is_young()) {
 232       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 233                              "incorrectly tagged (y: %d, surv: %d)",
 234                              curr->bottom(), curr->end(),
 235                              curr->is_young(), curr->is_survivor());
 236       ret = false;
 237     }
 238     ++length;
 239     last = curr;
 240     curr = curr->get_next_young_region();
 241   }
 242   ret = ret && (length == _length);
 243 
 244   if (!ret) {
 245     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 246     gclog_or_tty->print_cr("###   list has %d entries, _length is %d",
 247                            length, _length);
 248   }
 249 
 250   return ret;
 251 }
 252 
 253 bool YoungList::check_list_empty(bool check_sample) {
 254   bool ret = true;
 255 
 256   if (_length != 0) {
 257     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
 258                   _length);
 259     ret = false;
 260   }
 261   if (check_sample && _last_sampled_rs_lengths != 0) {
 262     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 263     ret = false;
 264   }
 265   if (_head != NULL) {
 266     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 267     ret = false;
 268   }
 269   if (!ret) {
 270     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 271   }
 272 
 273   return ret;
 274 }
 275 
 276 void
 277 YoungList::rs_length_sampling_init() {
 278   _sampled_rs_lengths = 0;
 279   _curr               = _head;
 280 }
 281 
 282 bool
 283 YoungList::rs_length_sampling_more() {
 284   return _curr != NULL;
 285 }
 286 
 287 void
 288 YoungList::rs_length_sampling_next() {
 289   assert( _curr != NULL, "invariant" );
 290   size_t rs_length = _curr->rem_set()->occupied();
 291 
 292   _sampled_rs_lengths += rs_length;
 293 
 294   // The current region may not yet have been added to the
 295   // incremental collection set (it gets added when it is
 296   // retired as the current allocation region).
 297   if (_curr->in_collection_set()) {
 298     // Update the collection set policy information for this region
 299     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 300   }
 301 
 302   _curr = _curr->get_next_young_region();
 303   if (_curr == NULL) {
 304     _last_sampled_rs_lengths = _sampled_rs_lengths;
 305     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 306   }
 307 }
 308 
 309 void
 310 YoungList::reset_auxilary_lists() {
 311   guarantee( is_empty(), "young list should be empty" );
 312   assert(check_list_well_formed(), "young list should be well formed");
 313 
 314   // Add survivor regions to SurvRateGroup.
 315   _g1h->g1_policy()->note_start_adding_survivor_regions();
 316   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 317 
 318   for (HeapRegion* curr = _survivor_head;
 319        curr != NULL;
 320        curr = curr->get_next_young_region()) {
 321     _g1h->g1_policy()->set_region_survivors(curr);
 322 
 323     // The region is a non-empty survivor so let's add it to
 324     // the incremental collection set for the next evacuation
 325     // pause.
 326     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 327   }
 328   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 329 
 330   _head   = _survivor_head;
 331   _length = _survivor_length;
 332   if (_survivor_head != NULL) {
 333     assert(_survivor_tail != NULL, "cause it shouldn't be");
 334     assert(_survivor_length > 0, "invariant");
 335     _survivor_tail->set_next_young_region(NULL);
 336   }
 337 
 338   // Don't clear the survivor list handles until the start of
 339   // the next evacuation pause - we need it in order to re-tag
 340   // the survivor regions from this evacuation pause as 'young'
 341   // at the start of the next.
 342 
 343   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 344 
 345   assert(check_list_well_formed(), "young list should be well formed");
 346 }
 347 
 348 void YoungList::print() {
 349   HeapRegion* lists[] = {_head,   _survivor_head};
 350   const char* names[] = {"YOUNG", "SURVIVOR"};
 351 
 352   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 353     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 354     HeapRegion *curr = lists[list];
 355     if (curr == NULL)
 356       gclog_or_tty->print_cr("  empty");
 357     while (curr != NULL) {
 358       gclog_or_tty->print_cr("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
 359                              "age: %4d, y: %d, surv: %d",
 360                              curr->bottom(), curr->end(),
 361                              curr->top(),
 362                              curr->prev_top_at_mark_start(),
 363                              curr->next_top_at_mark_start(),
 364                              curr->top_at_conc_mark_count(),
 365                              curr->age_in_surv_rate_group_cond(),
 366                              curr->is_young(),
 367                              curr->is_survivor());
 368       curr = curr->get_next_young_region();
 369     }
 370   }
 371 
 372   gclog_or_tty->print_cr("");
 373 }
 374 
 375 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 376 {
 377   // Claim the right to put the region on the dirty cards region list
 378   // by installing a self pointer.
 379   HeapRegion* next = hr->get_next_dirty_cards_region();
 380   if (next == NULL) {
 381     HeapRegion* res = (HeapRegion*)
 382       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 383                           NULL);
 384     if (res == NULL) {
 385       HeapRegion* head;
 386       do {
 387         // Put the region to the dirty cards region list.
 388         head = _dirty_cards_region_list;
 389         next = (HeapRegion*)
 390           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 391         if (next == head) {
 392           assert(hr->get_next_dirty_cards_region() == hr,
 393                  "hr->get_next_dirty_cards_region() != hr");
 394           if (next == NULL) {
 395             // The last region in the list points to itself.
 396             hr->set_next_dirty_cards_region(hr);
 397           } else {
 398             hr->set_next_dirty_cards_region(next);
 399           }
 400         }
 401       } while (next != head);
 402     }
 403   }
 404 }
 405 
 406 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 407 {
 408   HeapRegion* head;
 409   HeapRegion* hr;
 410   do {
 411     head = _dirty_cards_region_list;
 412     if (head == NULL) {
 413       return NULL;
 414     }
 415     HeapRegion* new_head = head->get_next_dirty_cards_region();
 416     if (head == new_head) {
 417       // The last region.
 418       new_head = NULL;
 419     }
 420     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 421                                           head);
 422   } while (hr != head);
 423   assert(hr != NULL, "invariant");
 424   hr->set_next_dirty_cards_region(NULL);
 425   return hr;
 426 }
 427 
 428 void G1CollectedHeap::stop_conc_gc_threads() {
 429   _cg1r->stop();
 430   _cmThread->stop();
 431 }
 432 
 433 #ifdef ASSERT
 434 // A region is added to the collection set as it is retired
 435 // so an address p can point to a region which will be in the
 436 // collection set but has not yet been retired.  This method
 437 // therefore is only accurate during a GC pause after all
 438 // regions have been retired.  It is used for debugging
 439 // to check if an nmethod has references to objects that can
 440 // be move during a partial collection.  Though it can be
 441 // inaccurate, it is sufficient for G1 because the conservative
 442 // implementation of is_scavengable() for G1 will indicate that
 443 // all nmethods must be scanned during a partial collection.
 444 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 445   HeapRegion* hr = heap_region_containing(p);
 446   return hr != NULL && hr->in_collection_set();
 447 }
 448 #endif
 449 
 450 // Returns true if the reference points to an object that
 451 // can move in an incremental collecction.
 452 bool G1CollectedHeap::is_scavengable(const void* p) {
 453   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 454   G1CollectorPolicy* g1p = g1h->g1_policy();
 455   HeapRegion* hr = heap_region_containing(p);
 456   if (hr == NULL) {
 457      // perm gen (or null)
 458      return false;
 459   } else {
 460     return !hr->isHumongous();
 461   }
 462 }
 463 
 464 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 465   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 466   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
 467 
 468   // Count the dirty cards at the start.
 469   CountNonCleanMemRegionClosure count1(this);
 470   ct_bs->mod_card_iterate(&count1);
 471   int orig_count = count1.n();
 472 
 473   // First clear the logged cards.
 474   ClearLoggedCardTableEntryClosure clear;
 475   dcqs.set_closure(&clear);
 476   dcqs.apply_closure_to_all_completed_buffers();
 477   dcqs.iterate_closure_all_threads(false);
 478   clear.print_histo();
 479 
 480   // Now ensure that there's no dirty cards.
 481   CountNonCleanMemRegionClosure count2(this);
 482   ct_bs->mod_card_iterate(&count2);
 483   if (count2.n() != 0) {
 484     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 485                            count2.n(), orig_count);
 486   }
 487   guarantee(count2.n() == 0, "Card table should be clean.");
 488 
 489   RedirtyLoggedCardTableEntryClosure redirty;
 490   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 491   dcqs.apply_closure_to_all_completed_buffers();
 492   dcqs.iterate_closure_all_threads(false);
 493   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 494                          clear.calls(), orig_count);
 495   guarantee(redirty.calls() == clear.calls(),
 496             "Or else mechanism is broken.");
 497 
 498   CountNonCleanMemRegionClosure count3(this);
 499   ct_bs->mod_card_iterate(&count3);
 500   if (count3.n() != orig_count) {
 501     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 502                            orig_count, count3.n());
 503     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 504   }
 505 
 506   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 507 }
 508 
 509 // Private class members.
 510 
 511 G1CollectedHeap* G1CollectedHeap::_g1h;
 512 
 513 // Private methods.
 514 
 515 HeapRegion*
 516 G1CollectedHeap::new_region_try_secondary_free_list() {
 517   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 518   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 519     if (!_secondary_free_list.is_empty()) {
 520       if (G1ConcRegionFreeingVerbose) {
 521         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 522                                "secondary_free_list has "SIZE_FORMAT" entries",
 523                                _secondary_free_list.length());
 524       }
 525       // It looks as if there are free regions available on the
 526       // secondary_free_list. Let's move them to the free_list and try
 527       // again to allocate from it.
 528       append_secondary_free_list();
 529 
 530       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 531              "empty we should have moved at least one entry to the free_list");
 532       HeapRegion* res = _free_list.remove_head();
 533       if (G1ConcRegionFreeingVerbose) {
 534         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 535                                "allocated "HR_FORMAT" from secondary_free_list",
 536                                HR_FORMAT_PARAMS(res));
 537       }
 538       return res;
 539     }
 540 
 541     // Wait here until we get notifed either when (a) there are no
 542     // more free regions coming or (b) some regions have been moved on
 543     // the secondary_free_list.
 544     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 545   }
 546 
 547   if (G1ConcRegionFreeingVerbose) {
 548     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 549                            "could not allocate from secondary_free_list");
 550   }
 551   return NULL;
 552 }
 553 
 554 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 555   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 556          "the only time we use this to allocate a humongous region is "
 557          "when we are allocating a single humongous region");
 558 
 559   HeapRegion* res;
 560   if (G1StressConcRegionFreeing) {
 561     if (!_secondary_free_list.is_empty()) {
 562       if (G1ConcRegionFreeingVerbose) {
 563         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 564                                "forced to look at the secondary_free_list");
 565       }
 566       res = new_region_try_secondary_free_list();
 567       if (res != NULL) {
 568         return res;
 569       }
 570     }
 571   }
 572   res = _free_list.remove_head_or_null();
 573   if (res == NULL) {
 574     if (G1ConcRegionFreeingVerbose) {
 575       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 576                              "res == NULL, trying the secondary_free_list");
 577     }
 578     res = new_region_try_secondary_free_list();
 579   }
 580   if (res == NULL && do_expand) {
 581     ergo_verbose1(ErgoHeapSizing,
 582                   "attempt heap expansion",
 583                   ergo_format_reason("region allocation request failed")
 584                   ergo_format_byte("allocation request"),
 585                   word_size * HeapWordSize);
 586     if (expand(word_size * HeapWordSize)) {
 587       // Even though the heap was expanded, it might not have reached
 588       // the desired size. So, we cannot assume that the allocation
 589       // will succeed.
 590       res = _free_list.remove_head_or_null();
 591     }
 592   }
 593   return res;
 594 }
 595 
 596 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
 597                                                           size_t word_size) {
 598   assert(isHumongous(word_size), "word_size should be humongous");
 599   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 600 
 601   size_t first = G1_NULL_HRS_INDEX;
 602   if (num_regions == 1) {
 603     // Only one region to allocate, no need to go through the slower
 604     // path. The caller will attempt the expasion if this fails, so
 605     // let's not try to expand here too.
 606     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 607     if (hr != NULL) {
 608       first = hr->hrs_index();
 609     } else {
 610       first = G1_NULL_HRS_INDEX;
 611     }
 612   } else {
 613     // We can't allocate humongous regions while cleanupComplete() is
 614     // running, since some of the regions we find to be empty might not
 615     // yet be added to the free list and it is not straightforward to
 616     // know which list they are on so that we can remove them. Note
 617     // that we only need to do this if we need to allocate more than
 618     // one region to satisfy the current humongous allocation
 619     // request. If we are only allocating one region we use the common
 620     // region allocation code (see above).
 621     wait_while_free_regions_coming();
 622     append_secondary_free_list_if_not_empty_with_lock();
 623 
 624     if (free_regions() >= num_regions) {
 625       first = _hrs.find_contiguous(num_regions);
 626       if (first != G1_NULL_HRS_INDEX) {
 627         for (size_t i = first; i < first + num_regions; ++i) {
 628           HeapRegion* hr = region_at(i);
 629           assert(hr->is_empty(), "sanity");
 630           assert(is_on_master_free_list(hr), "sanity");
 631           hr->set_pending_removal(true);
 632         }
 633         _free_list.remove_all_pending(num_regions);
 634       }
 635     }
 636   }
 637   return first;
 638 }
 639 
 640 HeapWord*
 641 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first,
 642                                                            size_t num_regions,
 643                                                            size_t word_size) {
 644   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 645   assert(isHumongous(word_size), "word_size should be humongous");
 646   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 647 
 648   // Index of last region in the series + 1.
 649   size_t last = first + num_regions;
 650 
 651   // We need to initialize the region(s) we just discovered. This is
 652   // a bit tricky given that it can happen concurrently with
 653   // refinement threads refining cards on these regions and
 654   // potentially wanting to refine the BOT as they are scanning
 655   // those cards (this can happen shortly after a cleanup; see CR
 656   // 6991377). So we have to set up the region(s) carefully and in
 657   // a specific order.
 658 
 659   // The word size sum of all the regions we will allocate.
 660   size_t word_size_sum = num_regions * HeapRegion::GrainWords;
 661   assert(word_size <= word_size_sum, "sanity");
 662 
 663   // This will be the "starts humongous" region.
 664   HeapRegion* first_hr = region_at(first);
 665   // The header of the new object will be placed at the bottom of
 666   // the first region.
 667   HeapWord* new_obj = first_hr->bottom();
 668   // This will be the new end of the first region in the series that
 669   // should also match the end of the last region in the seriers.
 670   HeapWord* new_end = new_obj + word_size_sum;
 671   // This will be the new top of the first region that will reflect
 672   // this allocation.
 673   HeapWord* new_top = new_obj + word_size;
 674 
 675   // First, we need to zero the header of the space that we will be
 676   // allocating. When we update top further down, some refinement
 677   // threads might try to scan the region. By zeroing the header we
 678   // ensure that any thread that will try to scan the region will
 679   // come across the zero klass word and bail out.
 680   //
 681   // NOTE: It would not have been correct to have used
 682   // CollectedHeap::fill_with_object() and make the space look like
 683   // an int array. The thread that is doing the allocation will
 684   // later update the object header to a potentially different array
 685   // type and, for a very short period of time, the klass and length
 686   // fields will be inconsistent. This could cause a refinement
 687   // thread to calculate the object size incorrectly.
 688   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 689 
 690   // We will set up the first region as "starts humongous". This
 691   // will also update the BOT covering all the regions to reflect
 692   // that there is a single object that starts at the bottom of the
 693   // first region.
 694   first_hr->set_startsHumongous(new_top, new_end);
 695 
 696   // Then, if there are any, we will set up the "continues
 697   // humongous" regions.
 698   HeapRegion* hr = NULL;
 699   for (size_t i = first + 1; i < last; ++i) {
 700     hr = region_at(i);
 701     hr->set_continuesHumongous(first_hr);
 702   }
 703   // If we have "continues humongous" regions (hr != NULL), then the
 704   // end of the last one should match new_end.
 705   assert(hr == NULL || hr->end() == new_end, "sanity");
 706 
 707   // Up to this point no concurrent thread would have been able to
 708   // do any scanning on any region in this series. All the top
 709   // fields still point to bottom, so the intersection between
 710   // [bottom,top] and [card_start,card_end] will be empty. Before we
 711   // update the top fields, we'll do a storestore to make sure that
 712   // no thread sees the update to top before the zeroing of the
 713   // object header and the BOT initialization.
 714   OrderAccess::storestore();
 715 
 716   // Now that the BOT and the object header have been initialized,
 717   // we can update top of the "starts humongous" region.
 718   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 719          "new_top should be in this region");
 720   first_hr->set_top(new_top);
 721   if (_hr_printer.is_active()) {
 722     HeapWord* bottom = first_hr->bottom();
 723     HeapWord* end = first_hr->orig_end();
 724     if ((first + 1) == last) {
 725       // the series has a single humongous region
 726       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 727     } else {
 728       // the series has more than one humongous regions
 729       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 730     }
 731   }
 732 
 733   // Now, we will update the top fields of the "continues humongous"
 734   // regions. The reason we need to do this is that, otherwise,
 735   // these regions would look empty and this will confuse parts of
 736   // G1. For example, the code that looks for a consecutive number
 737   // of empty regions will consider them empty and try to
 738   // re-allocate them. We can extend is_empty() to also include
 739   // !continuesHumongous(), but it is easier to just update the top
 740   // fields here. The way we set top for all regions (i.e., top ==
 741   // end for all regions but the last one, top == new_top for the
 742   // last one) is actually used when we will free up the humongous
 743   // region in free_humongous_region().
 744   hr = NULL;
 745   for (size_t i = first + 1; i < last; ++i) {
 746     hr = region_at(i);
 747     if ((i + 1) == last) {
 748       // last continues humongous region
 749       assert(hr->bottom() < new_top && new_top <= hr->end(),
 750              "new_top should fall on this region");
 751       hr->set_top(new_top);
 752       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 753     } else {
 754       // not last one
 755       assert(new_top > hr->end(), "new_top should be above this region");
 756       hr->set_top(hr->end());
 757       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 758     }
 759   }
 760   // If we have continues humongous regions (hr != NULL), then the
 761   // end of the last one should match new_end and its top should
 762   // match new_top.
 763   assert(hr == NULL ||
 764          (hr->end() == new_end && hr->top() == new_top), "sanity");
 765 
 766   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 767   _summary_bytes_used += first_hr->used();
 768   _humongous_set.add(first_hr);
 769 
 770   return new_obj;
 771 }
 772 
 773 // If could fit into free regions w/o expansion, try.
 774 // Otherwise, if can expand, do so.
 775 // Otherwise, if using ex regions might help, try with ex given back.
 776 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 777   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 778 
 779   verify_region_sets_optional();
 780 
 781   size_t num_regions =
 782          round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 783   size_t x_size = expansion_regions();
 784   size_t fs = _hrs.free_suffix();
 785   size_t first = humongous_obj_allocate_find_first(num_regions, word_size);
 786   if (first == G1_NULL_HRS_INDEX) {
 787     // The only thing we can do now is attempt expansion.
 788     if (fs + x_size >= num_regions) {
 789       // If the number of regions we're trying to allocate for this
 790       // object is at most the number of regions in the free suffix,
 791       // then the call to humongous_obj_allocate_find_first() above
 792       // should have succeeded and we wouldn't be here.
 793       //
 794       // We should only be trying to expand when the free suffix is
 795       // not sufficient for the object _and_ we have some expansion
 796       // room available.
 797       assert(num_regions > fs, "earlier allocation should have succeeded");
 798 
 799       ergo_verbose1(ErgoHeapSizing,
 800                     "attempt heap expansion",
 801                     ergo_format_reason("humongous allocation request failed")
 802                     ergo_format_byte("allocation request"),
 803                     word_size * HeapWordSize);
 804       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 805         // Even though the heap was expanded, it might not have
 806         // reached the desired size. So, we cannot assume that the
 807         // allocation will succeed.
 808         first = humongous_obj_allocate_find_first(num_regions, word_size);
 809       }
 810     }
 811   }
 812 
 813   HeapWord* result = NULL;
 814   if (first != G1_NULL_HRS_INDEX) {
 815     result =
 816       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 817     assert(result != NULL, "it should always return a valid result");
 818 
 819     // A successful humongous object allocation changes the used space
 820     // information of the old generation so we need to recalculate the
 821     // sizes and update the jstat counters here.
 822     g1mm()->update_sizes();
 823   }
 824 
 825   verify_region_sets_optional();
 826 
 827   return result;
 828 }
 829 
 830 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 831   assert_heap_not_locked_and_not_at_safepoint();
 832   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 833 
 834   unsigned int dummy_gc_count_before;
 835   return attempt_allocation(word_size, &dummy_gc_count_before);
 836 }
 837 
 838 HeapWord*
 839 G1CollectedHeap::mem_allocate(size_t word_size,
 840                               bool*  gc_overhead_limit_was_exceeded) {
 841   assert_heap_not_locked_and_not_at_safepoint();
 842 
 843   // Loop until the allocation is satisified, or unsatisfied after GC.
 844   for (int try_count = 1; /* we'll return */; try_count += 1) {
 845     unsigned int gc_count_before;
 846 
 847     HeapWord* result = NULL;
 848     if (!isHumongous(word_size)) {
 849       result = attempt_allocation(word_size, &gc_count_before);
 850     } else {
 851       result = attempt_allocation_humongous(word_size, &gc_count_before);
 852     }
 853     if (result != NULL) {
 854       return result;
 855     }
 856 
 857     // Create the garbage collection operation...
 858     VM_G1CollectForAllocation op(gc_count_before, word_size);
 859     // ...and get the VM thread to execute it.
 860     VMThread::execute(&op);
 861 
 862     if (op.prologue_succeeded() && op.pause_succeeded()) {
 863       // If the operation was successful we'll return the result even
 864       // if it is NULL. If the allocation attempt failed immediately
 865       // after a Full GC, it's unlikely we'll be able to allocate now.
 866       HeapWord* result = op.result();
 867       if (result != NULL && !isHumongous(word_size)) {
 868         // Allocations that take place on VM operations do not do any
 869         // card dirtying and we have to do it here. We only have to do
 870         // this for non-humongous allocations, though.
 871         dirty_young_block(result, word_size);
 872       }
 873       return result;
 874     } else {
 875       assert(op.result() == NULL,
 876              "the result should be NULL if the VM op did not succeed");
 877     }
 878 
 879     // Give a warning if we seem to be looping forever.
 880     if ((QueuedAllocationWarningCount > 0) &&
 881         (try_count % QueuedAllocationWarningCount == 0)) {
 882       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 883     }
 884   }
 885 
 886   ShouldNotReachHere();
 887   return NULL;
 888 }
 889 
 890 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 891                                            unsigned int *gc_count_before_ret) {
 892   // Make sure you read the note in attempt_allocation_humongous().
 893 
 894   assert_heap_not_locked_and_not_at_safepoint();
 895   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 896          "be called for humongous allocation requests");
 897 
 898   // We should only get here after the first-level allocation attempt
 899   // (attempt_allocation()) failed to allocate.
 900 
 901   // We will loop until a) we manage to successfully perform the
 902   // allocation or b) we successfully schedule a collection which
 903   // fails to perform the allocation. b) is the only case when we'll
 904   // return NULL.
 905   HeapWord* result = NULL;
 906   for (int try_count = 1; /* we'll return */; try_count += 1) {
 907     bool should_try_gc;
 908     unsigned int gc_count_before;
 909 
 910     {
 911       MutexLockerEx x(Heap_lock);
 912 
 913       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 914                                                       false /* bot_updates */);
 915       if (result != NULL) {
 916         return result;
 917       }
 918 
 919       // If we reach here, attempt_allocation_locked() above failed to
 920       // allocate a new region. So the mutator alloc region should be NULL.
 921       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 922 
 923       if (GC_locker::is_active_and_needs_gc()) {
 924         if (g1_policy()->can_expand_young_list()) {
 925           // No need for an ergo verbose message here,
 926           // can_expand_young_list() does this when it returns true.
 927           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 928                                                       false /* bot_updates */);
 929           if (result != NULL) {
 930             return result;
 931           }
 932         }
 933         should_try_gc = false;
 934       } else {
 935         // Read the GC count while still holding the Heap_lock.
 936         gc_count_before = SharedHeap::heap()->total_collections();
 937         should_try_gc = true;
 938       }
 939     }
 940 
 941     if (should_try_gc) {
 942       bool succeeded;
 943       result = do_collection_pause(word_size, gc_count_before, &succeeded);
 944       if (result != NULL) {
 945         assert(succeeded, "only way to get back a non-NULL result");
 946         return result;
 947       }
 948 
 949       if (succeeded) {
 950         // If we get here we successfully scheduled a collection which
 951         // failed to allocate. No point in trying to allocate
 952         // further. We'll just return NULL.
 953         MutexLockerEx x(Heap_lock);
 954         *gc_count_before_ret = SharedHeap::heap()->total_collections();
 955         return NULL;
 956       }
 957     } else {
 958       GC_locker::stall_until_clear();
 959     }
 960 
 961     // We can reach here if we were unsuccessul in scheduling a
 962     // collection (because another thread beat us to it) or if we were
 963     // stalled due to the GC locker. In either can we should retry the
 964     // allocation attempt in case another thread successfully
 965     // performed a collection and reclaimed enough space. We do the
 966     // first attempt (without holding the Heap_lock) here and the
 967     // follow-on attempt will be at the start of the next loop
 968     // iteration (after taking the Heap_lock).
 969     result = _mutator_alloc_region.attempt_allocation(word_size,
 970                                                       false /* bot_updates */);
 971     if (result != NULL ){
 972       return result;
 973     }
 974 
 975     // Give a warning if we seem to be looping forever.
 976     if ((QueuedAllocationWarningCount > 0) &&
 977         (try_count % QueuedAllocationWarningCount == 0)) {
 978       warning("G1CollectedHeap::attempt_allocation_slow() "
 979               "retries %d times", try_count);
 980     }
 981   }
 982 
 983   ShouldNotReachHere();
 984   return NULL;
 985 }
 986 
 987 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 988                                           unsigned int * gc_count_before_ret) {
 989   // The structure of this method has a lot of similarities to
 990   // attempt_allocation_slow(). The reason these two were not merged
 991   // into a single one is that such a method would require several "if
 992   // allocation is not humongous do this, otherwise do that"
 993   // conditional paths which would obscure its flow. In fact, an early
 994   // version of this code did use a unified method which was harder to
 995   // follow and, as a result, it had subtle bugs that were hard to
 996   // track down. So keeping these two methods separate allows each to
 997   // be more readable. It will be good to keep these two in sync as
 998   // much as possible.
 999 
1000   assert_heap_not_locked_and_not_at_safepoint();
1001   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1002          "should only be called for humongous allocations");
1003 
1004   // We will loop until a) we manage to successfully perform the
1005   // allocation or b) we successfully schedule a collection which
1006   // fails to perform the allocation. b) is the only case when we'll
1007   // return NULL.
1008   HeapWord* result = NULL;
1009   for (int try_count = 1; /* we'll return */; try_count += 1) {
1010     bool should_try_gc;
1011     unsigned int gc_count_before;
1012 
1013     {
1014       MutexLockerEx x(Heap_lock);
1015 
1016       // Given that humongous objects are not allocated in young
1017       // regions, we'll first try to do the allocation without doing a
1018       // collection hoping that there's enough space in the heap.
1019       result = humongous_obj_allocate(word_size);
1020       if (result != NULL) {
1021         return result;
1022       }
1023 
1024       if (GC_locker::is_active_and_needs_gc()) {
1025         should_try_gc = false;
1026       } else {
1027         // Read the GC count while still holding the Heap_lock.
1028         gc_count_before = SharedHeap::heap()->total_collections();
1029         should_try_gc = true;
1030       }
1031     }
1032 
1033     if (should_try_gc) {
1034       // If we failed to allocate the humongous object, we should try to
1035       // do a collection pause (if we're allowed) in case it reclaims
1036       // enough space for the allocation to succeed after the pause.
1037 
1038       bool succeeded;
1039       result = do_collection_pause(word_size, gc_count_before, &succeeded);
1040       if (result != NULL) {
1041         assert(succeeded, "only way to get back a non-NULL result");
1042         return result;
1043       }
1044 
1045       if (succeeded) {
1046         // If we get here we successfully scheduled a collection which
1047         // failed to allocate. No point in trying to allocate
1048         // further. We'll just return NULL.
1049         MutexLockerEx x(Heap_lock);
1050         *gc_count_before_ret = SharedHeap::heap()->total_collections();
1051         return NULL;
1052       }
1053     } else {
1054       GC_locker::stall_until_clear();
1055     }
1056 
1057     // We can reach here if we were unsuccessul in scheduling a
1058     // collection (because another thread beat us to it) or if we were
1059     // stalled due to the GC locker. In either can we should retry the
1060     // allocation attempt in case another thread successfully
1061     // performed a collection and reclaimed enough space.  Give a
1062     // warning if we seem to be looping forever.
1063 
1064     if ((QueuedAllocationWarningCount > 0) &&
1065         (try_count % QueuedAllocationWarningCount == 0)) {
1066       warning("G1CollectedHeap::attempt_allocation_humongous() "
1067               "retries %d times", try_count);
1068     }
1069   }
1070 
1071   ShouldNotReachHere();
1072   return NULL;
1073 }
1074 
1075 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1076                                        bool expect_null_mutator_alloc_region) {
1077   assert_at_safepoint(true /* should_be_vm_thread */);
1078   assert(_mutator_alloc_region.get() == NULL ||
1079                                              !expect_null_mutator_alloc_region,
1080          "the current alloc region was unexpectedly found to be non-NULL");
1081 
1082   if (!isHumongous(word_size)) {
1083     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1084                                                       false /* bot_updates */);
1085   } else {
1086     return humongous_obj_allocate(word_size);
1087   }
1088 
1089   ShouldNotReachHere();
1090 }
1091 
1092 class PostMCRemSetClearClosure: public HeapRegionClosure {
1093   ModRefBarrierSet* _mr_bs;
1094 public:
1095   PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1096   bool doHeapRegion(HeapRegion* r) {
1097     r->reset_gc_time_stamp();
1098     if (r->continuesHumongous())
1099       return false;
1100     HeapRegionRemSet* hrrs = r->rem_set();
1101     if (hrrs != NULL) hrrs->clear();
1102     // You might think here that we could clear just the cards
1103     // corresponding to the used region.  But no: if we leave a dirty card
1104     // in a region we might allocate into, then it would prevent that card
1105     // from being enqueued, and cause it to be missed.
1106     // Re: the performance cost: we shouldn't be doing full GC anyway!
1107     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1108     return false;
1109   }
1110 };
1111 
1112 
1113 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1114   ModRefBarrierSet* _mr_bs;
1115 public:
1116   PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1117   bool doHeapRegion(HeapRegion* r) {
1118     if (r->continuesHumongous()) return false;
1119     if (r->used_region().word_size() != 0) {
1120       _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1121     }
1122     return false;
1123   }
1124 };
1125 
1126 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1127   G1CollectedHeap*   _g1h;
1128   UpdateRSOopClosure _cl;
1129   int                _worker_i;
1130 public:
1131   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1132     _cl(g1->g1_rem_set(), worker_i),
1133     _worker_i(worker_i),
1134     _g1h(g1)
1135   { }
1136 
1137   bool doHeapRegion(HeapRegion* r) {
1138     if (!r->continuesHumongous()) {
1139       _cl.set_from(r);
1140       r->oop_iterate(&_cl);
1141     }
1142     return false;
1143   }
1144 };
1145 
1146 class ParRebuildRSTask: public AbstractGangTask {
1147   G1CollectedHeap* _g1;
1148 public:
1149   ParRebuildRSTask(G1CollectedHeap* g1)
1150     : AbstractGangTask("ParRebuildRSTask"),
1151       _g1(g1)
1152   { }
1153 
1154   void work(int i) {
1155     RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1156     _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1157                                          HeapRegion::RebuildRSClaimValue);
1158   }
1159 };
1160 
1161 class PostCompactionPrinterClosure: public HeapRegionClosure {
1162 private:
1163   G1HRPrinter* _hr_printer;
1164 public:
1165   bool doHeapRegion(HeapRegion* hr) {
1166     assert(!hr->is_young(), "not expecting to find young regions");
1167     // We only generate output for non-empty regions.
1168     if (!hr->is_empty()) {
1169       if (!hr->isHumongous()) {
1170         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1171       } else if (hr->startsHumongous()) {
1172         if (hr->capacity() == HeapRegion::GrainBytes) {
1173           // single humongous region
1174           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1175         } else {
1176           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1177         }
1178       } else {
1179         assert(hr->continuesHumongous(), "only way to get here");
1180         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1181       }
1182     }
1183     return false;
1184   }
1185 
1186   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1187     : _hr_printer(hr_printer) { }
1188 };
1189 
1190 bool G1CollectedHeap::do_collection(bool explicit_gc,
1191                                     bool clear_all_soft_refs,
1192                                     size_t word_size) {
1193   assert_at_safepoint(true /* should_be_vm_thread */);
1194 
1195   if (GC_locker::check_active_before_gc()) {
1196     return false;
1197   }
1198 
1199   SvcGCMarker sgcm(SvcGCMarker::FULL);
1200   ResourceMark rm;
1201 
1202   if (PrintHeapAtGC) {
1203     Universe::print_heap_before_gc();
1204   }
1205 
1206   verify_region_sets_optional();
1207 
1208   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1209                            collector_policy()->should_clear_all_soft_refs();
1210 
1211   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1212 
1213   {
1214     IsGCActiveMark x;
1215 
1216     // Timing
1217     bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1218     assert(!system_gc || explicit_gc, "invariant");
1219     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1220     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1221     TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1222                 PrintGC, true, gclog_or_tty);
1223 
1224     TraceCollectorStats tcs(g1mm()->full_collection_counters());
1225     TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1226 
1227     double start = os::elapsedTime();
1228     g1_policy()->record_full_collection_start();
1229 
1230     wait_while_free_regions_coming();
1231     append_secondary_free_list_if_not_empty_with_lock();
1232 
1233     gc_prologue(true);
1234     increment_total_collections(true /* full gc */);
1235 
1236     size_t g1h_prev_used = used();
1237     assert(used() == recalculate_used(), "Should be equal");
1238 
1239     if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1240       HandleMark hm;  // Discard invalid handles created during verification
1241       gclog_or_tty->print(" VerifyBeforeGC:");
1242       prepare_for_verify();
1243       Universe::verify(/* allow dirty */ true,
1244                        /* silent      */ false,
1245                        /* option      */ VerifyOption_G1UsePrevMarking);
1246 
1247     }
1248     pre_full_gc_dump();
1249 
1250     COMPILER2_PRESENT(DerivedPointerTable::clear());
1251 
1252     // Disable discovery and empty the discovered lists
1253     // for the CM ref processor.
1254     ref_processor_cm()->disable_discovery();
1255     ref_processor_cm()->abandon_partial_discovery();
1256     ref_processor_cm()->verify_no_references_recorded();
1257 
1258     // Abandon current iterations of concurrent marking and concurrent
1259     // refinement, if any are in progress.
1260     concurrent_mark()->abort();
1261 
1262     // Make sure we'll choose a new allocation region afterwards.
1263     release_mutator_alloc_region();
1264     abandon_gc_alloc_regions();
1265     g1_rem_set()->cleanupHRRS();
1266     tear_down_region_lists();
1267 
1268     // We should call this after we retire any currently active alloc
1269     // regions so that all the ALLOC / RETIRE events are generated
1270     // before the start GC event.
1271     _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1272 
1273     // We may have added regions to the current incremental collection
1274     // set between the last GC or pause and now. We need to clear the
1275     // incremental collection set and then start rebuilding it afresh
1276     // after this full GC.
1277     abandon_collection_set(g1_policy()->inc_cset_head());
1278     g1_policy()->clear_incremental_cset();
1279     g1_policy()->stop_incremental_cset_building();
1280 
1281     empty_young_list();
1282     g1_policy()->set_full_young_gcs(true);
1283 
1284     // See the comments in g1CollectedHeap.hpp and
1285     // G1CollectedHeap::ref_processing_init() about
1286     // how reference processing currently works in G1.
1287 
1288     // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1289     ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1290 
1291     // Temporarily clear the STW ref processor's _is_alive_non_header field.
1292     ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1293 
1294     ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1295     ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1296 
1297     // Do collection work
1298     {
1299       HandleMark hm;  // Discard invalid handles created during gc
1300       G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1301     }
1302 
1303     assert(free_regions() == 0, "we should not have added any free regions");
1304     rebuild_region_lists();
1305 
1306     _summary_bytes_used = recalculate_used();
1307 
1308     // Enqueue any discovered reference objects that have
1309     // not been removed from the discovered lists.
1310     ref_processor_stw()->enqueue_discovered_references();
1311 
1312     COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1313 
1314     MemoryService::track_memory_usage();
1315 
1316     if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1317       HandleMark hm;  // Discard invalid handles created during verification
1318       gclog_or_tty->print(" VerifyAfterGC:");
1319       prepare_for_verify();
1320       Universe::verify(/* allow dirty */ false,
1321                        /* silent      */ false,
1322                        /* option      */ VerifyOption_G1UsePrevMarking);
1323 
1324     }
1325 
1326     assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1327     ref_processor_stw()->verify_no_references_recorded();
1328 
1329     // Note: since we've just done a full GC, concurrent
1330     // marking is no longer active. Therefore we need not
1331     // re-enable reference discovery for the CM ref processor.
1332     // That will be done at the start of the next marking cycle.
1333     assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1334     ref_processor_cm()->verify_no_references_recorded();
1335 
1336     reset_gc_time_stamp();
1337     // Since everything potentially moved, we will clear all remembered
1338     // sets, and clear all cards.  Later we will rebuild remebered
1339     // sets. We will also reset the GC time stamps of the regions.
1340     PostMCRemSetClearClosure rs_clear(mr_bs());
1341     heap_region_iterate(&rs_clear);
1342 
1343     // Resize the heap if necessary.
1344     resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1345 
1346     if (_hr_printer.is_active()) {
1347       // We should do this after we potentially resize the heap so
1348       // that all the COMMIT / UNCOMMIT events are generated before
1349       // the end GC event.
1350 
1351       PostCompactionPrinterClosure cl(hr_printer());
1352       heap_region_iterate(&cl);
1353 
1354       _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1355     }
1356 
1357     if (_cg1r->use_cache()) {
1358       _cg1r->clear_and_record_card_counts();
1359       _cg1r->clear_hot_cache();
1360     }
1361 
1362     // Rebuild remembered sets of all regions.
1363 
1364     if (G1CollectedHeap::use_parallel_gc_threads()) {
1365       ParRebuildRSTask rebuild_rs_task(this);
1366       assert(check_heap_region_claim_values(
1367              HeapRegion::InitialClaimValue), "sanity check");
1368       set_par_threads(workers()->total_workers());
1369       workers()->run_task(&rebuild_rs_task);
1370       set_par_threads(0);
1371       assert(check_heap_region_claim_values(
1372              HeapRegion::RebuildRSClaimValue), "sanity check");
1373       reset_heap_region_claim_values();
1374     } else {
1375       RebuildRSOutOfRegionClosure rebuild_rs(this);
1376       heap_region_iterate(&rebuild_rs);
1377     }
1378 
1379     if (PrintGC) {
1380       print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1381     }
1382 
1383     if (true) { // FIXME
1384       // Ask the permanent generation to adjust size for full collections
1385       perm()->compute_new_size();
1386     }
1387 
1388     // Start a new incremental collection set for the next pause
1389     assert(g1_policy()->collection_set() == NULL, "must be");
1390     g1_policy()->start_incremental_cset_building();
1391 
1392     // Clear the _cset_fast_test bitmap in anticipation of adding
1393     // regions to the incremental collection set for the next
1394     // evacuation pause.
1395     clear_cset_fast_test();
1396 
1397     init_mutator_alloc_region();
1398 
1399     double end = os::elapsedTime();
1400     g1_policy()->record_full_collection_end();
1401 
1402 #ifdef TRACESPINNING
1403     ParallelTaskTerminator::print_termination_counts();
1404 #endif
1405 
1406     gc_epilogue(true);
1407 
1408     // Discard all rset updates
1409     JavaThread::dirty_card_queue_set().abandon_logs();
1410     assert(!G1DeferredRSUpdate
1411            || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1412   }
1413 
1414   _young_list->reset_sampled_info();
1415   // At this point there should be no regions in the
1416   // entire heap tagged as young.
1417   assert( check_young_list_empty(true /* check_heap */),
1418     "young list should be empty at this point");
1419 
1420   // Update the number of full collections that have been completed.
1421   increment_full_collections_completed(false /* concurrent */);
1422 
1423   _hrs.verify_optional();
1424   verify_region_sets_optional();
1425 
1426   if (PrintHeapAtGC) {
1427     Universe::print_heap_after_gc();
1428   }
1429   g1mm()->update_sizes();
1430   post_full_gc_dump();
1431 
1432   return true;
1433 }
1434 
1435 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1436   // do_collection() will return whether it succeeded in performing
1437   // the GC. Currently, there is no facility on the
1438   // do_full_collection() API to notify the caller than the collection
1439   // did not succeed (e.g., because it was locked out by the GC
1440   // locker). So, right now, we'll ignore the return value.
1441   bool dummy = do_collection(true,                /* explicit_gc */
1442                              clear_all_soft_refs,
1443                              0                    /* word_size */);
1444 }
1445 
1446 // This code is mostly copied from TenuredGeneration.
1447 void
1448 G1CollectedHeap::
1449 resize_if_necessary_after_full_collection(size_t word_size) {
1450   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1451 
1452   // Include the current allocation, if any, and bytes that will be
1453   // pre-allocated to support collections, as "used".
1454   const size_t used_after_gc = used();
1455   const size_t capacity_after_gc = capacity();
1456   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1457 
1458   // This is enforced in arguments.cpp.
1459   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1460          "otherwise the code below doesn't make sense");
1461 
1462   // We don't have floating point command-line arguments
1463   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1464   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1465   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1466   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1467 
1468   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1469   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1470 
1471   // We have to be careful here as these two calculations can overflow
1472   // 32-bit size_t's.
1473   double used_after_gc_d = (double) used_after_gc;
1474   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1475   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1476 
1477   // Let's make sure that they are both under the max heap size, which
1478   // by default will make them fit into a size_t.
1479   double desired_capacity_upper_bound = (double) max_heap_size;
1480   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1481                                     desired_capacity_upper_bound);
1482   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1483                                     desired_capacity_upper_bound);
1484 
1485   // We can now safely turn them into size_t's.
1486   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1487   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1488 
1489   // This assert only makes sense here, before we adjust them
1490   // with respect to the min and max heap size.
1491   assert(minimum_desired_capacity <= maximum_desired_capacity,
1492          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1493                  "maximum_desired_capacity = "SIZE_FORMAT,
1494                  minimum_desired_capacity, maximum_desired_capacity));
1495 
1496   // Should not be greater than the heap max size. No need to adjust
1497   // it with respect to the heap min size as it's a lower bound (i.e.,
1498   // we'll try to make the capacity larger than it, not smaller).
1499   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1500   // Should not be less than the heap min size. No need to adjust it
1501   // with respect to the heap max size as it's an upper bound (i.e.,
1502   // we'll try to make the capacity smaller than it, not greater).
1503   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1504 
1505   if (capacity_after_gc < minimum_desired_capacity) {
1506     // Don't expand unless it's significant
1507     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1508     ergo_verbose4(ErgoHeapSizing,
1509                   "attempt heap expansion",
1510                   ergo_format_reason("capacity lower than "
1511                                      "min desired capacity after Full GC")
1512                   ergo_format_byte("capacity")
1513                   ergo_format_byte("occupancy")
1514                   ergo_format_byte_perc("min desired capacity"),
1515                   capacity_after_gc, used_after_gc,
1516                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1517     expand(expand_bytes);
1518 
1519     // No expansion, now see if we want to shrink
1520   } else if (capacity_after_gc > maximum_desired_capacity) {
1521     // Capacity too large, compute shrinking size
1522     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1523     ergo_verbose4(ErgoHeapSizing,
1524                   "attempt heap shrinking",
1525                   ergo_format_reason("capacity higher than "
1526                                      "max desired capacity after Full GC")
1527                   ergo_format_byte("capacity")
1528                   ergo_format_byte("occupancy")
1529                   ergo_format_byte_perc("max desired capacity"),
1530                   capacity_after_gc, used_after_gc,
1531                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1532     shrink(shrink_bytes);
1533   }
1534 }
1535 
1536 
1537 HeapWord*
1538 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1539                                            bool* succeeded) {
1540   assert_at_safepoint(true /* should_be_vm_thread */);
1541 
1542   *succeeded = true;
1543   // Let's attempt the allocation first.
1544   HeapWord* result =
1545     attempt_allocation_at_safepoint(word_size,
1546                                  false /* expect_null_mutator_alloc_region */);
1547   if (result != NULL) {
1548     assert(*succeeded, "sanity");
1549     return result;
1550   }
1551 
1552   // In a G1 heap, we're supposed to keep allocation from failing by
1553   // incremental pauses.  Therefore, at least for now, we'll favor
1554   // expansion over collection.  (This might change in the future if we can
1555   // do something smarter than full collection to satisfy a failed alloc.)
1556   result = expand_and_allocate(word_size);
1557   if (result != NULL) {
1558     assert(*succeeded, "sanity");
1559     return result;
1560   }
1561 
1562   // Expansion didn't work, we'll try to do a Full GC.
1563   bool gc_succeeded = do_collection(false, /* explicit_gc */
1564                                     false, /* clear_all_soft_refs */
1565                                     word_size);
1566   if (!gc_succeeded) {
1567     *succeeded = false;
1568     return NULL;
1569   }
1570 
1571   // Retry the allocation
1572   result = attempt_allocation_at_safepoint(word_size,
1573                                   true /* expect_null_mutator_alloc_region */);
1574   if (result != NULL) {
1575     assert(*succeeded, "sanity");
1576     return result;
1577   }
1578 
1579   // Then, try a Full GC that will collect all soft references.
1580   gc_succeeded = do_collection(false, /* explicit_gc */
1581                                true,  /* clear_all_soft_refs */
1582                                word_size);
1583   if (!gc_succeeded) {
1584     *succeeded = false;
1585     return NULL;
1586   }
1587 
1588   // Retry the allocation once more
1589   result = attempt_allocation_at_safepoint(word_size,
1590                                   true /* expect_null_mutator_alloc_region */);
1591   if (result != NULL) {
1592     assert(*succeeded, "sanity");
1593     return result;
1594   }
1595 
1596   assert(!collector_policy()->should_clear_all_soft_refs(),
1597          "Flag should have been handled and cleared prior to this point");
1598 
1599   // What else?  We might try synchronous finalization later.  If the total
1600   // space available is large enough for the allocation, then a more
1601   // complete compaction phase than we've tried so far might be
1602   // appropriate.
1603   assert(*succeeded, "sanity");
1604   return NULL;
1605 }
1606 
1607 // Attempting to expand the heap sufficiently
1608 // to support an allocation of the given "word_size".  If
1609 // successful, perform the allocation and return the address of the
1610 // allocated block, or else "NULL".
1611 
1612 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1613   assert_at_safepoint(true /* should_be_vm_thread */);
1614 
1615   verify_region_sets_optional();
1616 
1617   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1618   ergo_verbose1(ErgoHeapSizing,
1619                 "attempt heap expansion",
1620                 ergo_format_reason("allocation request failed")
1621                 ergo_format_byte("allocation request"),
1622                 word_size * HeapWordSize);
1623   if (expand(expand_bytes)) {
1624     _hrs.verify_optional();
1625     verify_region_sets_optional();
1626     return attempt_allocation_at_safepoint(word_size,
1627                                  false /* expect_null_mutator_alloc_region */);
1628   }
1629   return NULL;
1630 }
1631 
1632 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1633                                              HeapWord* new_end) {
1634   assert(old_end != new_end, "don't call this otherwise");
1635   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1636 
1637   // Update the committed mem region.
1638   _g1_committed.set_end(new_end);
1639   // Tell the card table about the update.
1640   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1641   // Tell the BOT about the update.
1642   _bot_shared->resize(_g1_committed.word_size());
1643 }
1644 
1645 bool G1CollectedHeap::expand(size_t expand_bytes) {
1646   size_t old_mem_size = _g1_storage.committed_size();
1647   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1648   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1649                                        HeapRegion::GrainBytes);
1650   ergo_verbose2(ErgoHeapSizing,
1651                 "expand the heap",
1652                 ergo_format_byte("requested expansion amount")
1653                 ergo_format_byte("attempted expansion amount"),
1654                 expand_bytes, aligned_expand_bytes);
1655 
1656   // First commit the memory.
1657   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1658   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1659   if (successful) {
1660     // Then propagate this update to the necessary data structures.
1661     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1662     update_committed_space(old_end, new_end);
1663 
1664     FreeRegionList expansion_list("Local Expansion List");
1665     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1666     assert(mr.start() == old_end, "post-condition");
1667     // mr might be a smaller region than what was requested if
1668     // expand_by() was unable to allocate the HeapRegion instances
1669     assert(mr.end() <= new_end, "post-condition");
1670 
1671     size_t actual_expand_bytes = mr.byte_size();
1672     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1673     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1674            "post-condition");
1675     if (actual_expand_bytes < aligned_expand_bytes) {
1676       // We could not expand _hrs to the desired size. In this case we
1677       // need to shrink the committed space accordingly.
1678       assert(mr.end() < new_end, "invariant");
1679 
1680       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1681       // First uncommit the memory.
1682       _g1_storage.shrink_by(diff_bytes);
1683       // Then propagate this update to the necessary data structures.
1684       update_committed_space(new_end, mr.end());
1685     }
1686     _free_list.add_as_tail(&expansion_list);
1687 
1688     if (_hr_printer.is_active()) {
1689       HeapWord* curr = mr.start();
1690       while (curr < mr.end()) {
1691         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1692         _hr_printer.commit(curr, curr_end);
1693         curr = curr_end;
1694       }
1695       assert(curr == mr.end(), "post-condition");
1696     }
1697     g1_policy()->record_new_heap_size(n_regions());
1698   } else {
1699     ergo_verbose0(ErgoHeapSizing,
1700                   "did not expand the heap",
1701                   ergo_format_reason("heap expansion operation failed"));
1702     // The expansion of the virtual storage space was unsuccessful.
1703     // Let's see if it was because we ran out of swap.
1704     if (G1ExitOnExpansionFailure &&
1705         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1706       // We had head room...
1707       vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1708     }
1709   }
1710   return successful;
1711 }
1712 
1713 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1714   size_t old_mem_size = _g1_storage.committed_size();
1715   size_t aligned_shrink_bytes =
1716     ReservedSpace::page_align_size_down(shrink_bytes);
1717   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1718                                          HeapRegion::GrainBytes);
1719   size_t num_regions_deleted = 0;
1720   MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1721   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1722   assert(mr.end() == old_end, "post-condition");
1723 
1724   ergo_verbose3(ErgoHeapSizing,
1725                 "shrink the heap",
1726                 ergo_format_byte("requested shrinking amount")
1727                 ergo_format_byte("aligned shrinking amount")
1728                 ergo_format_byte("attempted shrinking amount"),
1729                 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1730   if (mr.byte_size() > 0) {
1731     if (_hr_printer.is_active()) {
1732       HeapWord* curr = mr.end();
1733       while (curr > mr.start()) {
1734         HeapWord* curr_end = curr;
1735         curr -= HeapRegion::GrainWords;
1736         _hr_printer.uncommit(curr, curr_end);
1737       }
1738       assert(curr == mr.start(), "post-condition");
1739     }
1740 
1741     _g1_storage.shrink_by(mr.byte_size());
1742     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1743     assert(mr.start() == new_end, "post-condition");
1744 
1745     _expansion_regions += num_regions_deleted;
1746     update_committed_space(old_end, new_end);
1747     HeapRegionRemSet::shrink_heap(n_regions());
1748     g1_policy()->record_new_heap_size(n_regions());
1749   } else {
1750     ergo_verbose0(ErgoHeapSizing,
1751                   "did not shrink the heap",
1752                   ergo_format_reason("heap shrinking operation failed"));
1753   }
1754 }
1755 
1756 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1757   verify_region_sets_optional();
1758 
1759   // We should only reach here at the end of a Full GC which means we
1760   // should not not be holding to any GC alloc regions. The method
1761   // below will make sure of that and do any remaining clean up.
1762   abandon_gc_alloc_regions();
1763 
1764   // Instead of tearing down / rebuilding the free lists here, we
1765   // could instead use the remove_all_pending() method on free_list to
1766   // remove only the ones that we need to remove.
1767   tear_down_region_lists();  // We will rebuild them in a moment.
1768   shrink_helper(shrink_bytes);
1769   rebuild_region_lists();
1770 
1771   _hrs.verify_optional();
1772   verify_region_sets_optional();
1773 }
1774 
1775 // Public methods.
1776 
1777 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1778 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1779 #endif // _MSC_VER
1780 
1781 
1782 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1783   SharedHeap(policy_),
1784   _g1_policy(policy_),
1785   _dirty_card_queue_set(false),
1786   _into_cset_dirty_card_queue_set(false),
1787   _is_alive_closure_cm(this),
1788   _is_alive_closure_stw(this),
1789   _ref_processor_cm(NULL),
1790   _ref_processor_stw(NULL),
1791   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1792   _bot_shared(NULL),
1793   _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1794   _evac_failure_scan_stack(NULL) ,
1795   _mark_in_progress(false),
1796   _cg1r(NULL), _summary_bytes_used(0),
1797   _g1mm(NULL),
1798   _refine_cte_cl(NULL),
1799   _full_collection(false),
1800   _free_list("Master Free List"),
1801   _secondary_free_list("Secondary Free List"),
1802   _humongous_set("Master Humongous Set"),
1803   _free_regions_coming(false),
1804   _young_list(new YoungList(this)),
1805   _gc_time_stamp(0),
1806   _retained_old_gc_alloc_region(NULL),
1807   _surviving_young_words(NULL),
1808   _full_collections_completed(0),
1809   _in_cset_fast_test(NULL),
1810   _in_cset_fast_test_base(NULL),
1811   _dirty_cards_region_list(NULL) {
1812   _g1h = this; // To catch bugs.
1813   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1814     vm_exit_during_initialization("Failed necessary allocation.");
1815   }
1816 
1817   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1818 
1819   int n_queues = MAX2((int)ParallelGCThreads, 1);
1820   _task_queues = new RefToScanQueueSet(n_queues);
1821 
1822   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1823   assert(n_rem_sets > 0, "Invariant.");
1824 
1825   HeapRegionRemSetIterator** iter_arr =
1826     NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1827   for (int i = 0; i < n_queues; i++) {
1828     iter_arr[i] = new HeapRegionRemSetIterator();
1829   }
1830   _rem_set_iterator = iter_arr;
1831 
1832   for (int i = 0; i < n_queues; i++) {
1833     RefToScanQueue* q = new RefToScanQueue();
1834     q->initialize();
1835     _task_queues->register_queue(i, q);
1836   }
1837 
1838   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1839 }
1840 
1841 jint G1CollectedHeap::initialize() {
1842   CollectedHeap::pre_initialize();
1843   os::enable_vtime();
1844 
1845   // Necessary to satisfy locking discipline assertions.
1846 
1847   MutexLocker x(Heap_lock);
1848 
1849   // We have to initialize the printer before committing the heap, as
1850   // it will be used then.
1851   _hr_printer.set_active(G1PrintHeapRegions);
1852 
1853   // While there are no constraints in the GC code that HeapWordSize
1854   // be any particular value, there are multiple other areas in the
1855   // system which believe this to be true (e.g. oop->object_size in some
1856   // cases incorrectly returns the size in wordSize units rather than
1857   // HeapWordSize).
1858   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1859 
1860   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1861   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1862 
1863   // Ensure that the sizes are properly aligned.
1864   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1865   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1866 
1867   _cg1r = new ConcurrentG1Refine();
1868 
1869   // Reserve the maximum.
1870   PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1871   // Includes the perm-gen.
1872 
1873   // When compressed oops are enabled, the preferred heap base
1874   // is calculated by subtracting the requested size from the
1875   // 32Gb boundary and using the result as the base address for
1876   // heap reservation. If the requested size is not aligned to
1877   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1878   // into the ReservedHeapSpace constructor) then the actual
1879   // base of the reserved heap may end up differing from the
1880   // address that was requested (i.e. the preferred heap base).
1881   // If this happens then we could end up using a non-optimal
1882   // compressed oops mode.
1883 
1884   // Since max_byte_size is aligned to the size of a heap region (checked
1885   // above), we also need to align the perm gen size as it might not be.
1886   const size_t total_reserved = max_byte_size +
1887                                 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1888   Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1889 
1890   char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1891 
1892   ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1893                             UseLargePages, addr);
1894 
1895   if (UseCompressedOops) {
1896     if (addr != NULL && !heap_rs.is_reserved()) {
1897       // Failed to reserve at specified address - the requested memory
1898       // region is taken already, for example, by 'java' launcher.
1899       // Try again to reserver heap higher.
1900       addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1901 
1902       ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1903                                  UseLargePages, addr);
1904 
1905       if (addr != NULL && !heap_rs0.is_reserved()) {
1906         // Failed to reserve at specified address again - give up.
1907         addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1908         assert(addr == NULL, "");
1909 
1910         ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1911                                    UseLargePages, addr);
1912         heap_rs = heap_rs1;
1913       } else {
1914         heap_rs = heap_rs0;
1915       }
1916     }
1917   }
1918 
1919   if (!heap_rs.is_reserved()) {
1920     vm_exit_during_initialization("Could not reserve enough space for object heap");
1921     return JNI_ENOMEM;
1922   }
1923 
1924   // It is important to do this in a way such that concurrent readers can't
1925   // temporarily think somethings in the heap.  (I've actually seen this
1926   // happen in asserts: DLD.)
1927   _reserved.set_word_size(0);
1928   _reserved.set_start((HeapWord*)heap_rs.base());
1929   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1930 
1931   _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1932 
1933   // Create the gen rem set (and barrier set) for the entire reserved region.
1934   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1935   set_barrier_set(rem_set()->bs());
1936   if (barrier_set()->is_a(BarrierSet::ModRef)) {
1937     _mr_bs = (ModRefBarrierSet*)_barrier_set;
1938   } else {
1939     vm_exit_during_initialization("G1 requires a mod ref bs.");
1940     return JNI_ENOMEM;
1941   }
1942 
1943   // Also create a G1 rem set.
1944   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1945     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1946   } else {
1947     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1948     return JNI_ENOMEM;
1949   }
1950 
1951   // Carve out the G1 part of the heap.
1952 
1953   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
1954   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1955                            g1_rs.size()/HeapWordSize);
1956   ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1957 
1958   _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1959 
1960   _g1_storage.initialize(g1_rs, 0);
1961   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1962   _hrs.initialize((HeapWord*) _g1_reserved.start(),
1963                   (HeapWord*) _g1_reserved.end(),
1964                   _expansion_regions);
1965 
1966   // 6843694 - ensure that the maximum region index can fit
1967   // in the remembered set structures.
1968   const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1969   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1970 
1971   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1972   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1973   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1974             "too many cards per region");
1975 
1976   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
1977 
1978   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1979                                              heap_word_size(init_byte_size));
1980 
1981   _g1h = this;
1982 
1983    _in_cset_fast_test_length = max_regions();
1984    _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
1985 
1986    // We're biasing _in_cset_fast_test to avoid subtracting the
1987    // beginning of the heap every time we want to index; basically
1988    // it's the same with what we do with the card table.
1989    _in_cset_fast_test = _in_cset_fast_test_base -
1990                 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
1991 
1992    // Clear the _cset_fast_test bitmap in anticipation of adding
1993    // regions to the incremental collection set for the first
1994    // evacuation pause.
1995    clear_cset_fast_test();
1996 
1997   // Create the ConcurrentMark data structure and thread.
1998   // (Must do this late, so that "max_regions" is defined.)
1999   _cm       = new ConcurrentMark(heap_rs, (int) max_regions());
2000   _cmThread = _cm->cmThread();
2001 
2002   // Initialize the from_card cache structure of HeapRegionRemSet.
2003   HeapRegionRemSet::init_heap(max_regions());
2004 
2005   // Now expand into the initial heap size.
2006   if (!expand(init_byte_size)) {
2007     vm_exit_during_initialization("Failed to allocate initial heap.");
2008     return JNI_ENOMEM;
2009   }
2010 
2011   // Perform any initialization actions delegated to the policy.
2012   g1_policy()->init();
2013 
2014   g1_policy()->note_start_of_mark_thread();
2015 
2016   _refine_cte_cl =
2017     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2018                                     g1_rem_set(),
2019                                     concurrent_g1_refine());
2020   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2021 
2022   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2023                                                SATB_Q_FL_lock,
2024                                                G1SATBProcessCompletedThreshold,
2025                                                Shared_SATB_Q_lock);
2026 
2027   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2028                                                 DirtyCardQ_FL_lock,
2029                                                 concurrent_g1_refine()->yellow_zone(),
2030                                                 concurrent_g1_refine()->red_zone(),
2031                                                 Shared_DirtyCardQ_lock);
2032 
2033   if (G1DeferredRSUpdate) {
2034     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2035                                       DirtyCardQ_FL_lock,
2036                                       -1, // never trigger processing
2037                                       -1, // no limit on length
2038                                       Shared_DirtyCardQ_lock,
2039                                       &JavaThread::dirty_card_queue_set());
2040   }
2041 
2042   // Initialize the card queue set used to hold cards containing
2043   // references into the collection set.
2044   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2045                                              DirtyCardQ_FL_lock,
2046                                              -1, // never trigger processing
2047                                              -1, // no limit on length
2048                                              Shared_DirtyCardQ_lock,
2049                                              &JavaThread::dirty_card_queue_set());
2050 
2051   // In case we're keeping closure specialization stats, initialize those
2052   // counts and that mechanism.
2053   SpecializationStats::clear();
2054 
2055   // Do later initialization work for concurrent refinement.
2056   _cg1r->init();
2057 
2058   // Here we allocate the dummy full region that is required by the
2059   // G1AllocRegion class. If we don't pass an address in the reserved
2060   // space here, lots of asserts fire.
2061 
2062   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2063                                              _g1_reserved.start());
2064   // We'll re-use the same region whether the alloc region will
2065   // require BOT updates or not and, if it doesn't, then a non-young
2066   // region will complain that it cannot support allocations without
2067   // BOT updates. So we'll tag the dummy region as young to avoid that.
2068   dummy_region->set_young();
2069   // Make sure it's full.
2070   dummy_region->set_top(dummy_region->end());
2071   G1AllocRegion::setup(this, dummy_region);
2072 
2073   init_mutator_alloc_region();
2074 
2075   // Do create of the monitoring and management support so that
2076   // values in the heap have been properly initialized.
2077   _g1mm = new G1MonitoringSupport(this);
2078 
2079   return JNI_OK;
2080 }
2081 
2082 void G1CollectedHeap::ref_processing_init() {
2083   // Reference processing in G1 currently works as follows:
2084   //
2085   // * There are two reference processor instances. One is
2086   //   used to record and process discovered references
2087   //   during concurrent marking; the other is used to
2088   //   record and process references during STW pauses
2089   //   (both full and incremental).
2090   // * Both ref processors need to 'span' the entire heap as
2091   //   the regions in the collection set may be dotted around.
2092   //
2093   // * For the concurrent marking ref processor:
2094   //   * Reference discovery is enabled at initial marking.
2095   //   * Reference discovery is disabled and the discovered
2096   //     references processed etc during remarking.
2097   //   * Reference discovery is MT (see below).
2098   //   * Reference discovery requires a barrier (see below).
2099   //   * Reference processing may or may not be MT
2100   //     (depending on the value of ParallelRefProcEnabled
2101   //     and ParallelGCThreads).
2102   //   * A full GC disables reference discovery by the CM
2103   //     ref processor and abandons any entries on it's
2104   //     discovered lists.
2105   //
2106   // * For the STW processor:
2107   //   * Non MT discovery is enabled at the start of a full GC.
2108   //   * Processing and enqueueing during a full GC is non-MT.
2109   //   * During a full GC, references are processed after marking.
2110   //
2111   //   * Discovery (may or may not be MT) is enabled at the start
2112   //     of an incremental evacuation pause.
2113   //   * References are processed near the end of a STW evacuation pause.
2114   //   * For both types of GC:
2115   //     * Discovery is atomic - i.e. not concurrent.
2116   //     * Reference discovery will not need a barrier.
2117 
2118   SharedHeap::ref_processing_init();
2119   MemRegion mr = reserved_region();
2120 
2121   // Concurrent Mark ref processor
2122   _ref_processor_cm =
2123     new ReferenceProcessor(mr,    // span
2124                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2125                                 // mt processing
2126                            (int) ParallelGCThreads,
2127                                 // degree of mt processing
2128                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2129                                 // mt discovery
2130                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2131                                 // degree of mt discovery
2132                            false,
2133                                 // Reference discovery is not atomic
2134                            &_is_alive_closure_cm,
2135                                 // is alive closure
2136                                 // (for efficiency/performance)
2137                            true);
2138                                 // Setting next fields of discovered
2139                                 // lists requires a barrier.
2140 
2141   // STW ref processor
2142   _ref_processor_stw =
2143     new ReferenceProcessor(mr,    // span
2144                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2145                                 // mt processing
2146                            MAX2((int)ParallelGCThreads, 1),
2147                                 // degree of mt processing
2148                            (ParallelGCThreads > 1),
2149                                 // mt discovery
2150                            MAX2((int)ParallelGCThreads, 1),
2151                                 // degree of mt discovery
2152                            true,
2153                                 // Reference discovery is atomic
2154                            &_is_alive_closure_stw,
2155                                 // is alive closure
2156                                 // (for efficiency/performance)
2157                            false);
2158                                 // Setting next fields of discovered
2159                                 // lists requires a barrier.
2160 }
2161 
2162 size_t G1CollectedHeap::capacity() const {
2163   return _g1_committed.byte_size();
2164 }
2165 
2166 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2167                                                  DirtyCardQueue* into_cset_dcq,
2168                                                  bool concurrent,
2169                                                  int worker_i) {
2170   // Clean cards in the hot card cache
2171   concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2172 
2173   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2174   int n_completed_buffers = 0;
2175   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2176     n_completed_buffers++;
2177   }
2178   g1_policy()->record_update_rs_processed_buffers(worker_i,
2179                                                   (double) n_completed_buffers);
2180   dcqs.clear_n_completed_buffers();
2181   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2182 }
2183 
2184 
2185 // Computes the sum of the storage used by the various regions.
2186 
2187 size_t G1CollectedHeap::used() const {
2188   assert(Heap_lock->owner() != NULL,
2189          "Should be owned on this thread's behalf.");
2190   size_t result = _summary_bytes_used;
2191   // Read only once in case it is set to NULL concurrently
2192   HeapRegion* hr = _mutator_alloc_region.get();
2193   if (hr != NULL)
2194     result += hr->used();
2195   return result;
2196 }
2197 
2198 size_t G1CollectedHeap::used_unlocked() const {
2199   size_t result = _summary_bytes_used;
2200   return result;
2201 }
2202 
2203 class SumUsedClosure: public HeapRegionClosure {
2204   size_t _used;
2205 public:
2206   SumUsedClosure() : _used(0) {}
2207   bool doHeapRegion(HeapRegion* r) {
2208     if (!r->continuesHumongous()) {
2209       _used += r->used();
2210     }
2211     return false;
2212   }
2213   size_t result() { return _used; }
2214 };
2215 
2216 size_t G1CollectedHeap::recalculate_used() const {
2217   SumUsedClosure blk;
2218   heap_region_iterate(&blk);
2219   return blk.result();
2220 }
2221 
2222 size_t G1CollectedHeap::unsafe_max_alloc() {
2223   if (free_regions() > 0) return HeapRegion::GrainBytes;
2224   // otherwise, is there space in the current allocation region?
2225 
2226   // We need to store the current allocation region in a local variable
2227   // here. The problem is that this method doesn't take any locks and
2228   // there may be other threads which overwrite the current allocation
2229   // region field. attempt_allocation(), for example, sets it to NULL
2230   // and this can happen *after* the NULL check here but before the call
2231   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2232   // to be a problem in the optimized build, since the two loads of the
2233   // current allocation region field are optimized away.
2234   HeapRegion* hr = _mutator_alloc_region.get();
2235   if (hr == NULL) {
2236     return 0;
2237   }
2238   return hr->free();
2239 }
2240 
2241 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2242   return
2243     ((cause == GCCause::_gc_locker           && GCLockerInvokesConcurrent) ||
2244      (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2245 }
2246 
2247 #ifndef PRODUCT
2248 void G1CollectedHeap::allocate_dummy_regions() {
2249   // Let's fill up most of the region
2250   size_t word_size = HeapRegion::GrainWords - 1024;
2251   // And as a result the region we'll allocate will be humongous.
2252   guarantee(isHumongous(word_size), "sanity");
2253 
2254   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2255     // Let's use the existing mechanism for the allocation
2256     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2257     if (dummy_obj != NULL) {
2258       MemRegion mr(dummy_obj, word_size);
2259       CollectedHeap::fill_with_object(mr);
2260     } else {
2261       // If we can't allocate once, we probably cannot allocate
2262       // again. Let's get out of the loop.
2263       break;
2264     }
2265   }
2266 }
2267 #endif // !PRODUCT
2268 
2269 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2270   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2271 
2272   // We assume that if concurrent == true, then the caller is a
2273   // concurrent thread that was joined the Suspendible Thread
2274   // Set. If there's ever a cheap way to check this, we should add an
2275   // assert here.
2276 
2277   // We have already incremented _total_full_collections at the start
2278   // of the GC, so total_full_collections() represents how many full
2279   // collections have been started.
2280   unsigned int full_collections_started = total_full_collections();
2281 
2282   // Given that this method is called at the end of a Full GC or of a
2283   // concurrent cycle, and those can be nested (i.e., a Full GC can
2284   // interrupt a concurrent cycle), the number of full collections
2285   // completed should be either one (in the case where there was no
2286   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2287   // behind the number of full collections started.
2288 
2289   // This is the case for the inner caller, i.e. a Full GC.
2290   assert(concurrent ||
2291          (full_collections_started == _full_collections_completed + 1) ||
2292          (full_collections_started == _full_collections_completed + 2),
2293          err_msg("for inner caller (Full GC): full_collections_started = %u "
2294                  "is inconsistent with _full_collections_completed = %u",
2295                  full_collections_started, _full_collections_completed));
2296 
2297   // This is the case for the outer caller, i.e. the concurrent cycle.
2298   assert(!concurrent ||
2299          (full_collections_started == _full_collections_completed + 1),
2300          err_msg("for outer caller (concurrent cycle): "
2301                  "full_collections_started = %u "
2302                  "is inconsistent with _full_collections_completed = %u",
2303                  full_collections_started, _full_collections_completed));
2304 
2305   _full_collections_completed += 1;
2306 
2307   // We need to clear the "in_progress" flag in the CM thread before
2308   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2309   // is set) so that if a waiter requests another System.gc() it doesn't
2310   // incorrectly see that a marking cyle is still in progress.
2311   if (concurrent) {
2312     _cmThread->clear_in_progress();
2313   }
2314 
2315   // This notify_all() will ensure that a thread that called
2316   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2317   // and it's waiting for a full GC to finish will be woken up. It is
2318   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2319   FullGCCount_lock->notify_all();
2320 }
2321 
2322 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2323   assert_at_safepoint(true /* should_be_vm_thread */);
2324   GCCauseSetter gcs(this, cause);
2325   switch (cause) {
2326     case GCCause::_heap_inspection:
2327     case GCCause::_heap_dump: {
2328       HandleMark hm;
2329       do_full_collection(false);         // don't clear all soft refs
2330       break;
2331     }
2332     default: // XXX FIX ME
2333       ShouldNotReachHere(); // Unexpected use of this function
2334   }
2335 }
2336 
2337 void G1CollectedHeap::collect(GCCause::Cause cause) {
2338   // The caller doesn't have the Heap_lock
2339   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2340 
2341   unsigned int gc_count_before;
2342   unsigned int full_gc_count_before;
2343   {
2344     MutexLocker ml(Heap_lock);
2345 
2346     // Read the GC count while holding the Heap_lock
2347     gc_count_before = SharedHeap::heap()->total_collections();
2348     full_gc_count_before = SharedHeap::heap()->total_full_collections();
2349   }
2350 
2351   if (should_do_concurrent_full_gc(cause)) {
2352     // Schedule an initial-mark evacuation pause that will start a
2353     // concurrent cycle. We're setting word_size to 0 which means that
2354     // we are not requesting a post-GC allocation.
2355     VM_G1IncCollectionPause op(gc_count_before,
2356                                0,     /* word_size */
2357                                true,  /* should_initiate_conc_mark */
2358                                g1_policy()->max_pause_time_ms(),
2359                                cause);
2360     VMThread::execute(&op);
2361   } else {
2362     if (cause == GCCause::_gc_locker
2363         DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2364 
2365       // Schedule a standard evacuation pause. We're setting word_size
2366       // to 0 which means that we are not requesting a post-GC allocation.
2367       VM_G1IncCollectionPause op(gc_count_before,
2368                                  0,     /* word_size */
2369                                  false, /* should_initiate_conc_mark */
2370                                  g1_policy()->max_pause_time_ms(),
2371                                  cause);
2372       VMThread::execute(&op);
2373     } else {
2374       // Schedule a Full GC.
2375       VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2376       VMThread::execute(&op);
2377     }
2378   }
2379 }
2380 
2381 bool G1CollectedHeap::is_in(const void* p) const {
2382   HeapRegion* hr = _hrs.addr_to_region((HeapWord*) p);
2383   if (hr != NULL) {
2384     return hr->is_in(p);
2385   } else {
2386     return _perm_gen->as_gen()->is_in(p);
2387   }
2388 }
2389 
2390 // Iteration functions.
2391 
2392 // Iterates an OopClosure over all ref-containing fields of objects
2393 // within a HeapRegion.
2394 
2395 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2396   MemRegion _mr;
2397   OopClosure* _cl;
2398 public:
2399   IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2400     : _mr(mr), _cl(cl) {}
2401   bool doHeapRegion(HeapRegion* r) {
2402     if (! r->continuesHumongous()) {
2403       r->oop_iterate(_cl);
2404     }
2405     return false;
2406   }
2407 };
2408 
2409 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2410   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2411   heap_region_iterate(&blk);
2412   if (do_perm) {
2413     perm_gen()->oop_iterate(cl);
2414   }
2415 }
2416 
2417 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2418   IterateOopClosureRegionClosure blk(mr, cl);
2419   heap_region_iterate(&blk);
2420   if (do_perm) {
2421     perm_gen()->oop_iterate(cl);
2422   }
2423 }
2424 
2425 // Iterates an ObjectClosure over all objects within a HeapRegion.
2426 
2427 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2428   ObjectClosure* _cl;
2429 public:
2430   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2431   bool doHeapRegion(HeapRegion* r) {
2432     if (! r->continuesHumongous()) {
2433       r->object_iterate(_cl);
2434     }
2435     return false;
2436   }
2437 };
2438 
2439 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2440   IterateObjectClosureRegionClosure blk(cl);
2441   heap_region_iterate(&blk);
2442   if (do_perm) {
2443     perm_gen()->object_iterate(cl);
2444   }
2445 }
2446 
2447 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2448   // FIXME: is this right?
2449   guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2450 }
2451 
2452 // Calls a SpaceClosure on a HeapRegion.
2453 
2454 class SpaceClosureRegionClosure: public HeapRegionClosure {
2455   SpaceClosure* _cl;
2456 public:
2457   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2458   bool doHeapRegion(HeapRegion* r) {
2459     _cl->do_space(r);
2460     return false;
2461   }
2462 };
2463 
2464 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2465   SpaceClosureRegionClosure blk(cl);
2466   heap_region_iterate(&blk);
2467 }
2468 
2469 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2470   _hrs.iterate(cl);
2471 }
2472 
2473 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2474                                                HeapRegionClosure* cl) const {
2475   _hrs.iterate_from(r, cl);
2476 }
2477 
2478 void
2479 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2480                                                  int worker,
2481                                                  jint claim_value) {
2482   const size_t regions = n_regions();
2483   const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
2484   // try to spread out the starting points of the workers
2485   const size_t start_index = regions / worker_num * (size_t) worker;
2486 
2487   // each worker will actually look at all regions
2488   for (size_t count = 0; count < regions; ++count) {
2489     const size_t index = (start_index + count) % regions;
2490     assert(0 <= index && index < regions, "sanity");
2491     HeapRegion* r = region_at(index);
2492     // we'll ignore "continues humongous" regions (we'll process them
2493     // when we come across their corresponding "start humongous"
2494     // region) and regions already claimed
2495     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2496       continue;
2497     }
2498     // OK, try to claim it
2499     if (r->claimHeapRegion(claim_value)) {
2500       // success!
2501       assert(!r->continuesHumongous(), "sanity");
2502       if (r->startsHumongous()) {
2503         // If the region is "starts humongous" we'll iterate over its
2504         // "continues humongous" first; in fact we'll do them
2505         // first. The order is important. In on case, calling the
2506         // closure on the "starts humongous" region might de-allocate
2507         // and clear all its "continues humongous" regions and, as a
2508         // result, we might end up processing them twice. So, we'll do
2509         // them first (notice: most closures will ignore them anyway) and
2510         // then we'll do the "starts humongous" region.
2511         for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2512           HeapRegion* chr = region_at(ch_index);
2513 
2514           // if the region has already been claimed or it's not
2515           // "continues humongous" we're done
2516           if (chr->claim_value() == claim_value ||
2517               !chr->continuesHumongous()) {
2518             break;
2519           }
2520 
2521           // Noone should have claimed it directly. We can given
2522           // that we claimed its "starts humongous" region.
2523           assert(chr->claim_value() != claim_value, "sanity");
2524           assert(chr->humongous_start_region() == r, "sanity");
2525 
2526           if (chr->claimHeapRegion(claim_value)) {
2527             // we should always be able to claim it; noone else should
2528             // be trying to claim this region
2529 
2530             bool res2 = cl->doHeapRegion(chr);
2531             assert(!res2, "Should not abort");
2532 
2533             // Right now, this holds (i.e., no closure that actually
2534             // does something with "continues humongous" regions
2535             // clears them). We might have to weaken it in the future,
2536             // but let's leave these two asserts here for extra safety.
2537             assert(chr->continuesHumongous(), "should still be the case");
2538             assert(chr->humongous_start_region() == r, "sanity");
2539           } else {
2540             guarantee(false, "we should not reach here");
2541           }
2542         }
2543       }
2544 
2545       assert(!r->continuesHumongous(), "sanity");
2546       bool res = cl->doHeapRegion(r);
2547       assert(!res, "Should not abort");
2548     }
2549   }
2550 }
2551 
2552 class ResetClaimValuesClosure: public HeapRegionClosure {
2553 public:
2554   bool doHeapRegion(HeapRegion* r) {
2555     r->set_claim_value(HeapRegion::InitialClaimValue);
2556     return false;
2557   }
2558 };
2559 
2560 void
2561 G1CollectedHeap::reset_heap_region_claim_values() {
2562   ResetClaimValuesClosure blk;
2563   heap_region_iterate(&blk);
2564 }
2565 
2566 #ifdef ASSERT
2567 // This checks whether all regions in the heap have the correct claim
2568 // value. I also piggy-backed on this a check to ensure that the
2569 // humongous_start_region() information on "continues humongous"
2570 // regions is correct.
2571 
2572 class CheckClaimValuesClosure : public HeapRegionClosure {
2573 private:
2574   jint _claim_value;
2575   size_t _failures;
2576   HeapRegion* _sh_region;
2577 public:
2578   CheckClaimValuesClosure(jint claim_value) :
2579     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2580   bool doHeapRegion(HeapRegion* r) {
2581     if (r->claim_value() != _claim_value) {
2582       gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2583                              "claim value = %d, should be %d",
2584                              r->bottom(), r->end(), r->claim_value(),
2585                              _claim_value);
2586       ++_failures;
2587     }
2588     if (!r->isHumongous()) {
2589       _sh_region = NULL;
2590     } else if (r->startsHumongous()) {
2591       _sh_region = r;
2592     } else if (r->continuesHumongous()) {
2593       if (r->humongous_start_region() != _sh_region) {
2594         gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2595                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2596                                r->bottom(), r->end(),
2597                                r->humongous_start_region(),
2598                                _sh_region);
2599         ++_failures;
2600       }
2601     }
2602     return false;
2603   }
2604   size_t failures() {
2605     return _failures;
2606   }
2607 };
2608 
2609 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2610   CheckClaimValuesClosure cl(claim_value);
2611   heap_region_iterate(&cl);
2612   return cl.failures() == 0;
2613 }
2614 #endif // ASSERT
2615 
2616 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2617   HeapRegion* r = g1_policy()->collection_set();
2618   while (r != NULL) {
2619     HeapRegion* next = r->next_in_collection_set();
2620     if (cl->doHeapRegion(r)) {
2621       cl->incomplete();
2622       return;
2623     }
2624     r = next;
2625   }
2626 }
2627 
2628 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2629                                                   HeapRegionClosure *cl) {
2630   if (r == NULL) {
2631     // The CSet is empty so there's nothing to do.
2632     return;
2633   }
2634 
2635   assert(r->in_collection_set(),
2636          "Start region must be a member of the collection set.");
2637   HeapRegion* cur = r;
2638   while (cur != NULL) {
2639     HeapRegion* next = cur->next_in_collection_set();
2640     if (cl->doHeapRegion(cur) && false) {
2641       cl->incomplete();
2642       return;
2643     }
2644     cur = next;
2645   }
2646   cur = g1_policy()->collection_set();
2647   while (cur != r) {
2648     HeapRegion* next = cur->next_in_collection_set();
2649     if (cl->doHeapRegion(cur) && false) {
2650       cl->incomplete();
2651       return;
2652     }
2653     cur = next;
2654   }
2655 }
2656 
2657 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2658   return n_regions() > 0 ? region_at(0) : NULL;
2659 }
2660 
2661 
2662 Space* G1CollectedHeap::space_containing(const void* addr) const {
2663   Space* res = heap_region_containing(addr);
2664   if (res == NULL)
2665     res = perm_gen()->space_containing(addr);
2666   return res;
2667 }
2668 
2669 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2670   Space* sp = space_containing(addr);
2671   if (sp != NULL) {
2672     return sp->block_start(addr);
2673   }
2674   return NULL;
2675 }
2676 
2677 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2678   Space* sp = space_containing(addr);
2679   assert(sp != NULL, "block_size of address outside of heap");
2680   return sp->block_size(addr);
2681 }
2682 
2683 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2684   Space* sp = space_containing(addr);
2685   return sp->block_is_obj(addr);
2686 }
2687 
2688 bool G1CollectedHeap::supports_tlab_allocation() const {
2689   return true;
2690 }
2691 
2692 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2693   return HeapRegion::GrainBytes;
2694 }
2695 
2696 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2697   // Return the remaining space in the cur alloc region, but not less than
2698   // the min TLAB size.
2699 
2700   // Also, this value can be at most the humongous object threshold,
2701   // since we can't allow tlabs to grow big enough to accomodate
2702   // humongous objects.
2703 
2704   HeapRegion* hr = _mutator_alloc_region.get();
2705   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2706   if (hr == NULL) {
2707     return max_tlab_size;
2708   } else {
2709     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2710   }
2711 }
2712 
2713 size_t G1CollectedHeap::max_capacity() const {
2714   return _g1_reserved.byte_size();
2715 }
2716 
2717 jlong G1CollectedHeap::millis_since_last_gc() {
2718   // assert(false, "NYI");
2719   return 0;
2720 }
2721 
2722 void G1CollectedHeap::prepare_for_verify() {
2723   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2724     ensure_parsability(false);
2725   }
2726   g1_rem_set()->prepare_for_verify();
2727 }
2728 
2729 class VerifyLivenessOopClosure: public OopClosure {
2730   G1CollectedHeap* _g1h;
2731   VerifyOption _vo;
2732 public:
2733   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2734     _g1h(g1h), _vo(vo)
2735   { }
2736   void do_oop(narrowOop *p) { do_oop_work(p); }
2737   void do_oop(      oop *p) { do_oop_work(p); }
2738 
2739   template <class T> void do_oop_work(T *p) {
2740     oop obj = oopDesc::load_decode_heap_oop(p);
2741     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2742               "Dead object referenced by a not dead object");
2743   }
2744 };
2745 
2746 class VerifyObjsInRegionClosure: public ObjectClosure {
2747 private:
2748   G1CollectedHeap* _g1h;
2749   size_t _live_bytes;
2750   HeapRegion *_hr;
2751   VerifyOption _vo;
2752 public:
2753   // _vo == UsePrevMarking -> use "prev" marking information,
2754   // _vo == UseNextMarking -> use "next" marking information,
2755   // _vo == UseMarkWord    -> use mark word from object header.
2756   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2757     : _live_bytes(0), _hr(hr), _vo(vo) {
2758     _g1h = G1CollectedHeap::heap();
2759   }
2760   void do_object(oop o) {
2761     VerifyLivenessOopClosure isLive(_g1h, _vo);
2762     assert(o != NULL, "Huh?");
2763     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2764       // If the object is alive according to the mark word,
2765       // then verify that the marking information agrees.
2766       // Note we can't verify the contra-positive of the
2767       // above: if the object is dead (according to the mark
2768       // word), it may not be marked, or may have been marked
2769       // but has since became dead, or may have been allocated
2770       // since the last marking.
2771       if (_vo == VerifyOption_G1UseMarkWord) {
2772         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2773       }
2774 
2775       o->oop_iterate(&isLive);
2776       if (!_hr->obj_allocated_since_prev_marking(o)) {
2777         size_t obj_size = o->size();    // Make sure we don't overflow
2778         _live_bytes += (obj_size * HeapWordSize);
2779       }
2780     }
2781   }
2782   size_t live_bytes() { return _live_bytes; }
2783 };
2784 
2785 class PrintObjsInRegionClosure : public ObjectClosure {
2786   HeapRegion *_hr;
2787   G1CollectedHeap *_g1;
2788 public:
2789   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2790     _g1 = G1CollectedHeap::heap();
2791   };
2792 
2793   void do_object(oop o) {
2794     if (o != NULL) {
2795       HeapWord *start = (HeapWord *) o;
2796       size_t word_sz = o->size();
2797       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2798                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2799                           (void*) o, word_sz,
2800                           _g1->isMarkedPrev(o),
2801                           _g1->isMarkedNext(o),
2802                           _hr->obj_allocated_since_prev_marking(o));
2803       HeapWord *end = start + word_sz;
2804       HeapWord *cur;
2805       int *val;
2806       for (cur = start; cur < end; cur++) {
2807         val = (int *) cur;
2808         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2809       }
2810     }
2811   }
2812 };
2813 
2814 class VerifyRegionClosure: public HeapRegionClosure {
2815 private:
2816   bool         _allow_dirty;
2817   bool         _par;
2818   VerifyOption _vo;
2819   bool         _failures;
2820 public:
2821   // _vo == UsePrevMarking -> use "prev" marking information,
2822   // _vo == UseNextMarking -> use "next" marking information,
2823   // _vo == UseMarkWord    -> use mark word from object header.
2824   VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
2825     : _allow_dirty(allow_dirty),
2826       _par(par),
2827       _vo(vo),
2828       _failures(false) {}
2829 
2830   bool failures() {
2831     return _failures;
2832   }
2833 
2834   bool doHeapRegion(HeapRegion* r) {
2835     guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2836               "Should be unclaimed at verify points.");
2837     if (!r->continuesHumongous()) {
2838       bool failures = false;
2839       r->verify(_allow_dirty, _vo, &failures);
2840       if (failures) {
2841         _failures = true;
2842       } else {
2843         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2844         r->object_iterate(&not_dead_yet_cl);
2845         if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2846           gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2847                                  "max_live_bytes "SIZE_FORMAT" "
2848                                  "< calculated "SIZE_FORMAT,
2849                                  r->bottom(), r->end(),
2850                                  r->max_live_bytes(),
2851                                  not_dead_yet_cl.live_bytes());
2852           _failures = true;
2853         }
2854       }
2855     }
2856     return false; // stop the region iteration if we hit a failure
2857   }
2858 };
2859 
2860 class VerifyRootsClosure: public OopsInGenClosure {
2861 private:
2862   G1CollectedHeap* _g1h;
2863   VerifyOption     _vo;
2864   bool             _failures;
2865 public:
2866   // _vo == UsePrevMarking -> use "prev" marking information,
2867   // _vo == UseNextMarking -> use "next" marking information,
2868   // _vo == UseMarkWord    -> use mark word from object header.
2869   VerifyRootsClosure(VerifyOption vo) :
2870     _g1h(G1CollectedHeap::heap()),
2871     _vo(vo),
2872     _failures(false) { }
2873 
2874   bool failures() { return _failures; }
2875 
2876   template <class T> void do_oop_nv(T* p) {
2877     T heap_oop = oopDesc::load_heap_oop(p);
2878     if (!oopDesc::is_null(heap_oop)) {
2879       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2880       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2881         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2882                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2883         if (_vo == VerifyOption_G1UseMarkWord) {
2884           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2885         }
2886         obj->print_on(gclog_or_tty);
2887         _failures = true;
2888       }
2889     }
2890   }
2891 
2892   void do_oop(oop* p)       { do_oop_nv(p); }
2893   void do_oop(narrowOop* p) { do_oop_nv(p); }
2894 };
2895 
2896 // This is the task used for parallel heap verification.
2897 
2898 class G1ParVerifyTask: public AbstractGangTask {
2899 private:
2900   G1CollectedHeap* _g1h;
2901   bool             _allow_dirty;
2902   VerifyOption     _vo;
2903   bool             _failures;
2904 
2905 public:
2906   // _vo == UsePrevMarking -> use "prev" marking information,
2907   // _vo == UseNextMarking -> use "next" marking information,
2908   // _vo == UseMarkWord    -> use mark word from object header.
2909   G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
2910     AbstractGangTask("Parallel verify task"),
2911     _g1h(g1h),
2912     _allow_dirty(allow_dirty),
2913     _vo(vo),
2914     _failures(false) { }
2915 
2916   bool failures() {
2917     return _failures;
2918   }
2919 
2920   void work(int worker_i) {
2921     HandleMark hm;
2922     VerifyRegionClosure blk(_allow_dirty, true, _vo);
2923     _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2924                                           HeapRegion::ParVerifyClaimValue);
2925     if (blk.failures()) {
2926       _failures = true;
2927     }
2928   }
2929 };
2930 
2931 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2932   verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
2933 }
2934 
2935 void G1CollectedHeap::verify(bool allow_dirty,
2936                              bool silent,
2937                              VerifyOption vo) {
2938   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2939     if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
2940     VerifyRootsClosure rootsCl(vo);
2941     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2942 
2943     // We apply the relevant closures to all the oops in the
2944     // system dictionary, the string table and the code cache.
2945     const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
2946 
2947     process_strong_roots(true,      // activate StrongRootsScope
2948                          true,      // we set "collecting perm gen" to true,
2949                                     // so we don't reset the dirty cards in the perm gen.
2950                          SharedHeap::ScanningOption(so),  // roots scanning options
2951                          &rootsCl,
2952                          &blobsCl,
2953                          &rootsCl);
2954 
2955     // If we're verifying after the marking phase of a Full GC then we can't
2956     // treat the perm gen as roots into the G1 heap. Some of the objects in
2957     // the perm gen may be dead and hence not marked. If one of these dead
2958     // objects is considered to be a root then we may end up with a false
2959     // "Root location <x> points to dead ob <y>" failure.
2960     if (vo != VerifyOption_G1UseMarkWord) {
2961       // Since we used "collecting_perm_gen" == true above, we will not have
2962       // checked the refs from perm into the G1-collected heap. We check those
2963       // references explicitly below. Whether the relevant cards are dirty
2964       // is checked further below in the rem set verification.
2965       if (!silent) { gclog_or_tty->print("Permgen roots "); }
2966       perm_gen()->oop_iterate(&rootsCl);
2967     }
2968     bool failures = rootsCl.failures();
2969 
2970     if (vo != VerifyOption_G1UseMarkWord) {
2971       // If we're verifying during a full GC then the region sets
2972       // will have been torn down at the start of the GC. Therefore
2973       // verifying the region sets will fail. So we only verify
2974       // the region sets when not in a full GC.
2975       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
2976       verify_region_sets();
2977     }
2978 
2979     if (!silent) { gclog_or_tty->print("HeapRegions "); }
2980     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2981       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2982              "sanity check");
2983 
2984       G1ParVerifyTask task(this, allow_dirty, vo);
2985       int n_workers = workers()->total_workers();
2986       set_par_threads(n_workers);
2987       workers()->run_task(&task);
2988       set_par_threads(0);
2989       if (task.failures()) {
2990         failures = true;
2991       }
2992 
2993       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2994              "sanity check");
2995 
2996       reset_heap_region_claim_values();
2997 
2998       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2999              "sanity check");
3000     } else {
3001       VerifyRegionClosure blk(allow_dirty, false, vo);
3002       heap_region_iterate(&blk);
3003       if (blk.failures()) {
3004         failures = true;
3005       }
3006     }
3007     if (!silent) gclog_or_tty->print("RemSet ");
3008     rem_set()->verify();
3009 
3010     if (failures) {
3011       gclog_or_tty->print_cr("Heap:");
3012       print_on(gclog_or_tty, true /* extended */);
3013       gclog_or_tty->print_cr("");
3014 #ifndef PRODUCT
3015       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3016         concurrent_mark()->print_reachable("at-verification-failure",
3017                                            vo, false /* all */);
3018       }
3019 #endif
3020       gclog_or_tty->flush();
3021     }
3022     guarantee(!failures, "there should not have been any failures");
3023   } else {
3024     if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3025   }
3026 }
3027 
3028 class PrintRegionClosure: public HeapRegionClosure {
3029   outputStream* _st;
3030 public:
3031   PrintRegionClosure(outputStream* st) : _st(st) {}
3032   bool doHeapRegion(HeapRegion* r) {
3033     r->print_on(_st);
3034     return false;
3035   }
3036 };
3037 
3038 void G1CollectedHeap::print() const { print_on(tty); }
3039 
3040 void G1CollectedHeap::print_on(outputStream* st) const {
3041   print_on(st, PrintHeapAtGCExtended);
3042 }
3043 
3044 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
3045   st->print(" %-20s", "garbage-first heap");
3046   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3047             capacity()/K, used_unlocked()/K);
3048   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3049             _g1_storage.low_boundary(),
3050             _g1_storage.high(),
3051             _g1_storage.high_boundary());
3052   st->cr();
3053   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3054   size_t young_regions = _young_list->length();
3055   st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3056             young_regions, young_regions * HeapRegion::GrainBytes / K);
3057   size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3058   st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3059             survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3060   st->cr();
3061   perm()->as_gen()->print_on(st);
3062   if (extended) {
3063     st->cr();
3064     print_on_extended(st);
3065   }
3066 }
3067 
3068 void G1CollectedHeap::print_on_extended(outputStream* st) const {
3069   PrintRegionClosure blk(st);
3070   heap_region_iterate(&blk);
3071 }
3072 
3073 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3074   if (G1CollectedHeap::use_parallel_gc_threads()) {
3075     workers()->print_worker_threads_on(st);
3076   }
3077   _cmThread->print_on(st);
3078   st->cr();
3079   _cm->print_worker_threads_on(st);
3080   _cg1r->print_worker_threads_on(st);
3081   st->cr();
3082 }
3083 
3084 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3085   if (G1CollectedHeap::use_parallel_gc_threads()) {
3086     workers()->threads_do(tc);
3087   }
3088   tc->do_thread(_cmThread);
3089   _cg1r->threads_do(tc);
3090 }
3091 
3092 void G1CollectedHeap::print_tracing_info() const {
3093   // We'll overload this to mean "trace GC pause statistics."
3094   if (TraceGen0Time || TraceGen1Time) {
3095     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3096     // to that.
3097     g1_policy()->print_tracing_info();
3098   }
3099   if (G1SummarizeRSetStats) {
3100     g1_rem_set()->print_summary_info();
3101   }
3102   if (G1SummarizeConcMark) {
3103     concurrent_mark()->print_summary_info();
3104   }
3105   g1_policy()->print_yg_surv_rate_info();
3106   SpecializationStats::print();
3107 }
3108 
3109 #ifndef PRODUCT
3110 // Helpful for debugging RSet issues.
3111 
3112 class PrintRSetsClosure : public HeapRegionClosure {
3113 private:
3114   const char* _msg;
3115   size_t _occupied_sum;
3116 
3117 public:
3118   bool doHeapRegion(HeapRegion* r) {
3119     HeapRegionRemSet* hrrs = r->rem_set();
3120     size_t occupied = hrrs->occupied();
3121     _occupied_sum += occupied;
3122 
3123     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3124                            HR_FORMAT_PARAMS(r));
3125     if (occupied == 0) {
3126       gclog_or_tty->print_cr("  RSet is empty");
3127     } else {
3128       hrrs->print();
3129     }
3130     gclog_or_tty->print_cr("----------");
3131     return false;
3132   }
3133 
3134   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3135     gclog_or_tty->cr();
3136     gclog_or_tty->print_cr("========================================");
3137     gclog_or_tty->print_cr(msg);
3138     gclog_or_tty->cr();
3139   }
3140 
3141   ~PrintRSetsClosure() {
3142     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3143     gclog_or_tty->print_cr("========================================");
3144     gclog_or_tty->cr();
3145   }
3146 };
3147 
3148 void G1CollectedHeap::print_cset_rsets() {
3149   PrintRSetsClosure cl("Printing CSet RSets");
3150   collection_set_iterate(&cl);
3151 }
3152 
3153 void G1CollectedHeap::print_all_rsets() {
3154   PrintRSetsClosure cl("Printing All RSets");;
3155   heap_region_iterate(&cl);
3156 }
3157 #endif // PRODUCT
3158 
3159 G1CollectedHeap* G1CollectedHeap::heap() {
3160   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3161          "not a garbage-first heap");
3162   return _g1h;
3163 }
3164 
3165 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3166   // always_do_update_barrier = false;
3167   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3168   // Call allocation profiler
3169   AllocationProfiler::iterate_since_last_gc();
3170   // Fill TLAB's and such
3171   ensure_parsability(true);
3172 }
3173 
3174 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3175   // FIXME: what is this about?
3176   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3177   // is set.
3178   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3179                         "derived pointer present"));
3180   // always_do_update_barrier = true;
3181 
3182   // We have just completed a GC. Update the soft reference
3183   // policy with the new heap occupancy
3184   Universe::update_heap_info_at_gc();
3185 }
3186 
3187 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3188                                                unsigned int gc_count_before,
3189                                                bool* succeeded) {
3190   assert_heap_not_locked_and_not_at_safepoint();
3191   g1_policy()->record_stop_world_start();
3192   VM_G1IncCollectionPause op(gc_count_before,
3193                              word_size,
3194                              false, /* should_initiate_conc_mark */
3195                              g1_policy()->max_pause_time_ms(),
3196                              GCCause::_g1_inc_collection_pause);
3197   VMThread::execute(&op);
3198 
3199   HeapWord* result = op.result();
3200   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3201   assert(result == NULL || ret_succeeded,
3202          "the result should be NULL if the VM did not succeed");
3203   *succeeded = ret_succeeded;
3204 
3205   assert_heap_not_locked();
3206   return result;
3207 }
3208 
3209 void
3210 G1CollectedHeap::doConcurrentMark() {
3211   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3212   if (!_cmThread->in_progress()) {
3213     _cmThread->set_started();
3214     CGC_lock->notify();
3215   }
3216 }
3217 
3218 // <NEW PREDICTION>
3219 
3220 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3221                                                        bool young) {
3222   return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3223 }
3224 
3225 void G1CollectedHeap::check_if_region_is_too_expensive(double
3226                                                            predicted_time_ms) {
3227   _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3228 }
3229 
3230 size_t G1CollectedHeap::pending_card_num() {
3231   size_t extra_cards = 0;
3232   JavaThread *curr = Threads::first();
3233   while (curr != NULL) {
3234     DirtyCardQueue& dcq = curr->dirty_card_queue();
3235     extra_cards += dcq.size();
3236     curr = curr->next();
3237   }
3238   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3239   size_t buffer_size = dcqs.buffer_size();
3240   size_t buffer_num = dcqs.completed_buffers_num();
3241   return buffer_size * buffer_num + extra_cards;
3242 }
3243 
3244 size_t G1CollectedHeap::max_pending_card_num() {
3245   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3246   size_t buffer_size = dcqs.buffer_size();
3247   size_t buffer_num  = dcqs.completed_buffers_num();
3248   int thread_num  = Threads::number_of_threads();
3249   return (buffer_num + thread_num) * buffer_size;
3250 }
3251 
3252 size_t G1CollectedHeap::cards_scanned() {
3253   return g1_rem_set()->cardsScanned();
3254 }
3255 
3256 void
3257 G1CollectedHeap::setup_surviving_young_words() {
3258   guarantee( _surviving_young_words == NULL, "pre-condition" );
3259   size_t array_length = g1_policy()->young_cset_length();
3260   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3261   if (_surviving_young_words == NULL) {
3262     vm_exit_out_of_memory(sizeof(size_t) * array_length,
3263                           "Not enough space for young surv words summary.");
3264   }
3265   memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3266 #ifdef ASSERT
3267   for (size_t i = 0;  i < array_length; ++i) {
3268     assert( _surviving_young_words[i] == 0, "memset above" );
3269   }
3270 #endif // !ASSERT
3271 }
3272 
3273 void
3274 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3275   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3276   size_t array_length = g1_policy()->young_cset_length();
3277   for (size_t i = 0; i < array_length; ++i)
3278     _surviving_young_words[i] += surv_young_words[i];
3279 }
3280 
3281 void
3282 G1CollectedHeap::cleanup_surviving_young_words() {
3283   guarantee( _surviving_young_words != NULL, "pre-condition" );
3284   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3285   _surviving_young_words = NULL;
3286 }
3287 
3288 // </NEW PREDICTION>
3289 
3290 #ifdef ASSERT
3291 class VerifyCSetClosure: public HeapRegionClosure {
3292 public:
3293   bool doHeapRegion(HeapRegion* hr) {
3294     // Here we check that the CSet region's RSet is ready for parallel
3295     // iteration. The fields that we'll verify are only manipulated
3296     // when the region is part of a CSet and is collected. Afterwards,
3297     // we reset these fields when we clear the region's RSet (when the
3298     // region is freed) so they are ready when the region is
3299     // re-allocated. The only exception to this is if there's an
3300     // evacuation failure and instead of freeing the region we leave
3301     // it in the heap. In that case, we reset these fields during
3302     // evacuation failure handling.
3303     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3304 
3305     // Here's a good place to add any other checks we'd like to
3306     // perform on CSet regions.
3307     return false;
3308   }
3309 };
3310 #endif // ASSERT
3311 
3312 #if TASKQUEUE_STATS
3313 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3314   st->print_raw_cr("GC Task Stats");
3315   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3316   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3317 }
3318 
3319 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3320   print_taskqueue_stats_hdr(st);
3321 
3322   TaskQueueStats totals;
3323   const int n = workers() != NULL ? workers()->total_workers() : 1;
3324   for (int i = 0; i < n; ++i) {
3325     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3326     totals += task_queue(i)->stats;
3327   }
3328   st->print_raw("tot "); totals.print(st); st->cr();
3329 
3330   DEBUG_ONLY(totals.verify());
3331 }
3332 
3333 void G1CollectedHeap::reset_taskqueue_stats() {
3334   const int n = workers() != NULL ? workers()->total_workers() : 1;
3335   for (int i = 0; i < n; ++i) {
3336     task_queue(i)->stats.reset();
3337   }
3338 }
3339 #endif // TASKQUEUE_STATS
3340 
3341 bool
3342 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3343   assert_at_safepoint(true /* should_be_vm_thread */);
3344   guarantee(!is_gc_active(), "collection is not reentrant");
3345 
3346   if (GC_locker::check_active_before_gc()) {
3347     return false;
3348   }
3349 
3350   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3351   ResourceMark rm;
3352 
3353   if (PrintHeapAtGC) {
3354     Universe::print_heap_before_gc();
3355   }
3356 
3357   verify_region_sets_optional();
3358   verify_dirty_young_regions();
3359 
3360   {
3361     // This call will decide whether this pause is an initial-mark
3362     // pause. If it is, during_initial_mark_pause() will return true
3363     // for the duration of this pause.
3364     g1_policy()->decide_on_conc_mark_initiation();
3365 
3366     char verbose_str[128];
3367     sprintf(verbose_str, "GC pause ");
3368     if (g1_policy()->full_young_gcs()) {
3369       strcat(verbose_str, "(young)");
3370     } else {
3371       strcat(verbose_str, "(partial)");
3372     }
3373     if (g1_policy()->during_initial_mark_pause()) {
3374       strcat(verbose_str, " (initial-mark)");
3375       // We are about to start a marking cycle, so we increment the
3376       // full collection counter.
3377       increment_total_full_collections();
3378     }
3379 
3380     // if PrintGCDetails is on, we'll print long statistics information
3381     // in the collector policy code, so let's not print this as the output
3382     // is messy if we do.
3383     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3384     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3385     TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3386 
3387     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3388     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3389 
3390     // If the secondary_free_list is not empty, append it to the
3391     // free_list. No need to wait for the cleanup operation to finish;
3392     // the region allocation code will check the secondary_free_list
3393     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3394     // set, skip this step so that the region allocation code has to
3395     // get entries from the secondary_free_list.
3396     if (!G1StressConcRegionFreeing) {
3397       append_secondary_free_list_if_not_empty_with_lock();
3398     }
3399 
3400     assert(check_young_list_well_formed(),
3401       "young list should be well formed");
3402 
3403     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3404       IsGCActiveMark x;
3405 
3406       gc_prologue(false);
3407       increment_total_collections(false /* full gc */);
3408       increment_gc_time_stamp();
3409 
3410       if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3411         HandleMark hm;  // Discard invalid handles created during verification
3412         gclog_or_tty->print(" VerifyBeforeGC:");
3413         prepare_for_verify();
3414         Universe::verify(/* allow dirty */ false,
3415                          /* silent      */ false,
3416                          /* option      */ VerifyOption_G1UsePrevMarking);
3417 
3418       }
3419 
3420       COMPILER2_PRESENT(DerivedPointerTable::clear());
3421 
3422       // Please see comment in g1CollectedHeap.hpp and
3423       // G1CollectedHeap::ref_processing_init() to see how
3424       // reference processing currently works in G1.
3425 
3426       // Enable discovery in the STW reference processor
3427       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3428                                             true /*verify_no_refs*/);
3429 
3430       {
3431         // We want to temporarily turn off discovery by the
3432         // CM ref processor, if necessary, and turn it back on
3433         // on again later if we do. Using a scoped
3434         // NoRefDiscovery object will do this.
3435         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3436 
3437         // Forget the current alloc region (we might even choose it to be part
3438         // of the collection set!).
3439         release_mutator_alloc_region();
3440 
3441         // We should call this after we retire the mutator alloc
3442         // region(s) so that all the ALLOC / RETIRE events are generated
3443         // before the start GC event.
3444         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3445 
3446         // The elapsed time induced by the start time below deliberately elides
3447         // the possible verification above.
3448         double start_time_sec = os::elapsedTime();
3449         size_t start_used_bytes = used();
3450 
3451 #if YOUNG_LIST_VERBOSE
3452         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3453         _young_list->print();
3454         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3455 #endif // YOUNG_LIST_VERBOSE
3456 
3457         g1_policy()->record_collection_pause_start(start_time_sec,
3458                                                    start_used_bytes);
3459 
3460 #if YOUNG_LIST_VERBOSE
3461         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3462         _young_list->print();
3463 #endif // YOUNG_LIST_VERBOSE
3464 
3465         if (g1_policy()->during_initial_mark_pause()) {
3466           concurrent_mark()->checkpointRootsInitialPre();
3467         }
3468         perm_gen()->save_marks();
3469 
3470         // We must do this before any possible evacuation that should propagate
3471         // marks.
3472         if (mark_in_progress()) {
3473           double start_time_sec = os::elapsedTime();
3474 
3475           _cm->drainAllSATBBuffers();
3476           double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3477           g1_policy()->record_satb_drain_time(finish_mark_ms);
3478         }
3479         // Record the number of elements currently on the mark stack, so we
3480         // only iterate over these.  (Since evacuation may add to the mark
3481         // stack, doing more exposes race conditions.)  If no mark is in
3482         // progress, this will be zero.
3483         _cm->set_oops_do_bound();
3484 
3485         if (mark_in_progress()) {
3486           concurrent_mark()->newCSet();
3487         }
3488 
3489 #if YOUNG_LIST_VERBOSE
3490         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3491         _young_list->print();
3492         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3493 #endif // YOUNG_LIST_VERBOSE
3494 
3495         g1_policy()->choose_collection_set(target_pause_time_ms);
3496 
3497         if (_hr_printer.is_active()) {
3498           HeapRegion* hr = g1_policy()->collection_set();
3499           while (hr != NULL) {
3500             G1HRPrinter::RegionType type;
3501             if (!hr->is_young()) {
3502               type = G1HRPrinter::Old;
3503             } else if (hr->is_survivor()) {
3504               type = G1HRPrinter::Survivor;
3505             } else {
3506               type = G1HRPrinter::Eden;
3507             }
3508             _hr_printer.cset(hr);
3509             hr = hr->next_in_collection_set();
3510           }
3511         }
3512 
3513         // We have chosen the complete collection set. If marking is
3514         // active then, we clear the region fields of any of the
3515         // concurrent marking tasks whose region fields point into
3516         // the collection set as these values will become stale. This
3517         // will cause the owning marking threads to claim a new region
3518         // when marking restarts.
3519         if (mark_in_progress()) {
3520           concurrent_mark()->reset_active_task_region_fields_in_cset();
3521         }
3522 
3523 #ifdef ASSERT
3524         VerifyCSetClosure cl;
3525         collection_set_iterate(&cl);
3526 #endif // ASSERT
3527 
3528         setup_surviving_young_words();
3529 
3530         // Initialize the GC alloc regions.
3531         init_gc_alloc_regions();
3532 
3533         // Actually do the work...
3534         evacuate_collection_set();
3535 
3536         free_collection_set(g1_policy()->collection_set());
3537         g1_policy()->clear_collection_set();
3538 
3539         cleanup_surviving_young_words();
3540 
3541         // Start a new incremental collection set for the next pause.
3542         g1_policy()->start_incremental_cset_building();
3543 
3544         // Clear the _cset_fast_test bitmap in anticipation of adding
3545         // regions to the incremental collection set for the next
3546         // evacuation pause.
3547         clear_cset_fast_test();
3548 
3549         _young_list->reset_sampled_info();
3550 
3551         // Don't check the whole heap at this point as the
3552         // GC alloc regions from this pause have been tagged
3553         // as survivors and moved on to the survivor list.
3554         // Survivor regions will fail the !is_young() check.
3555         assert(check_young_list_empty(false /* check_heap */),
3556           "young list should be empty");
3557 
3558 #if YOUNG_LIST_VERBOSE
3559         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3560         _young_list->print();
3561 #endif // YOUNG_LIST_VERBOSE
3562 
3563         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3564                                             _young_list->first_survivor_region(),
3565                                             _young_list->last_survivor_region());
3566 
3567         _young_list->reset_auxilary_lists();
3568 
3569         if (evacuation_failed()) {
3570           _summary_bytes_used = recalculate_used();
3571         } else {
3572           // The "used" of the the collection set have already been subtracted
3573           // when they were freed.  Add in the bytes evacuated.
3574           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3575         }
3576 
3577         if (g1_policy()->during_initial_mark_pause()) {
3578           concurrent_mark()->checkpointRootsInitialPost();
3579           set_marking_started();
3580           // CAUTION: after the doConcurrentMark() call below,
3581           // the concurrent marking thread(s) could be running
3582           // concurrently with us. Make sure that anything after
3583           // this point does not assume that we are the only GC thread
3584           // running. Note: of course, the actual marking work will
3585           // not start until the safepoint itself is released in
3586           // ConcurrentGCThread::safepoint_desynchronize().
3587           doConcurrentMark();
3588         }
3589 
3590         allocate_dummy_regions();
3591 
3592 #if YOUNG_LIST_VERBOSE
3593         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3594         _young_list->print();
3595         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3596 #endif // YOUNG_LIST_VERBOSE
3597 
3598         init_mutator_alloc_region();
3599 
3600         {
3601           size_t expand_bytes = g1_policy()->expansion_amount();
3602           if (expand_bytes > 0) {
3603             size_t bytes_before = capacity();
3604             if (!expand(expand_bytes)) {
3605               // We failed to expand the heap so let's verify that
3606               // committed/uncommitted amount match the backing store
3607               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3608               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3609             }
3610           }
3611         }
3612 
3613         double end_time_sec = os::elapsedTime();
3614         double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3615         g1_policy()->record_pause_time_ms(pause_time_ms);
3616         g1_policy()->record_collection_pause_end();
3617 
3618         MemoryService::track_memory_usage();
3619 
3620         // In prepare_for_verify() below we'll need to scan the deferred
3621         // update buffers to bring the RSets up-to-date if
3622         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3623         // the update buffers we'll probably need to scan cards on the
3624         // regions we just allocated to (i.e., the GC alloc
3625         // regions). However, during the last GC we called
3626         // set_saved_mark() on all the GC alloc regions, so card
3627         // scanning might skip the [saved_mark_word()...top()] area of
3628         // those regions (i.e., the area we allocated objects into
3629         // during the last GC). But it shouldn't. Given that
3630         // saved_mark_word() is conditional on whether the GC time stamp
3631         // on the region is current or not, by incrementing the GC time
3632         // stamp here we invalidate all the GC time stamps on all the
3633         // regions and saved_mark_word() will simply return top() for
3634         // all the regions. This is a nicer way of ensuring this rather
3635         // than iterating over the regions and fixing them. In fact, the
3636         // GC time stamp increment here also ensures that
3637         // saved_mark_word() will return top() between pauses, i.e.,
3638         // during concurrent refinement. So we don't need the
3639         // is_gc_active() check to decided which top to use when
3640         // scanning cards (see CR 7039627).
3641         increment_gc_time_stamp();
3642 
3643         if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3644           HandleMark hm;  // Discard invalid handles created during verification
3645           gclog_or_tty->print(" VerifyAfterGC:");
3646           prepare_for_verify();
3647           Universe::verify(/* allow dirty */ true,
3648                            /* silent      */ false,
3649                            /* option      */ VerifyOption_G1UsePrevMarking);
3650         }
3651 
3652         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3653         ref_processor_stw()->verify_no_references_recorded();
3654 
3655         // CM reference discovery will be re-enabled if necessary.
3656       }
3657 
3658       {
3659         size_t expand_bytes = g1_policy()->expansion_amount();
3660         if (expand_bytes > 0) {
3661           size_t bytes_before = capacity();
3662           // No need for an ergo verbose message here,
3663           // expansion_amount() does this when it returns a value > 0.
3664           if (!expand(expand_bytes)) {
3665             // We failed to expand the heap so let's verify that
3666             // committed/uncommitted amount match the backing store
3667             assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3668             assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3669           }
3670         }
3671       }
3672 
3673       // We should do this after we potentially expand the heap so
3674       // that all the COMMIT events are generated before the end GC
3675       // event, and after we retire the GC alloc regions so that all
3676       // RETIRE events are generated before the end GC event.
3677       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3678 
3679       // We have to do this after we decide whether to expand the heap or not.
3680       g1_policy()->print_heap_transition();
3681 
3682       if (mark_in_progress()) {
3683         concurrent_mark()->update_g1_committed();
3684       }
3685 
3686 #ifdef TRACESPINNING
3687       ParallelTaskTerminator::print_termination_counts();
3688 #endif
3689 
3690       gc_epilogue(false);
3691     }
3692 
3693     if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3694       gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3695       print_tracing_info();
3696       vm_exit(-1);
3697     }
3698   }
3699 
3700   _hrs.verify_optional();
3701   verify_region_sets_optional();
3702 
3703   TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3704   TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3705 
3706   if (PrintHeapAtGC) {
3707     Universe::print_heap_after_gc();
3708   }
3709   g1mm()->update_sizes();
3710 
3711   if (G1SummarizeRSetStats &&
3712       (G1SummarizeRSetStatsPeriod > 0) &&
3713       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3714     g1_rem_set()->print_summary_info();
3715   }
3716 
3717   return true;
3718 }
3719 
3720 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3721 {
3722   size_t gclab_word_size;
3723   switch (purpose) {
3724     case GCAllocForSurvived:
3725       gclab_word_size = YoungPLABSize;
3726       break;
3727     case GCAllocForTenured:
3728       gclab_word_size = OldPLABSize;
3729       break;
3730     default:
3731       assert(false, "unknown GCAllocPurpose");
3732       gclab_word_size = OldPLABSize;
3733       break;
3734   }
3735   return gclab_word_size;
3736 }
3737 
3738 void G1CollectedHeap::init_mutator_alloc_region() {
3739   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3740   _mutator_alloc_region.init();
3741 }
3742 
3743 void G1CollectedHeap::release_mutator_alloc_region() {
3744   _mutator_alloc_region.release();
3745   assert(_mutator_alloc_region.get() == NULL, "post-condition");
3746 }
3747 
3748 void G1CollectedHeap::init_gc_alloc_regions() {
3749   assert_at_safepoint(true /* should_be_vm_thread */);
3750 
3751   _survivor_gc_alloc_region.init();
3752   _old_gc_alloc_region.init();
3753   HeapRegion* retained_region = _retained_old_gc_alloc_region;
3754   _retained_old_gc_alloc_region = NULL;
3755 
3756   // We will discard the current GC alloc region if:
3757   // a) it's in the collection set (it can happen!),
3758   // b) it's already full (no point in using it),
3759   // c) it's empty (this means that it was emptied during
3760   // a cleanup and it should be on the free list now), or
3761   // d) it's humongous (this means that it was emptied
3762   // during a cleanup and was added to the free list, but
3763   // has been subseqently used to allocate a humongous
3764   // object that may be less than the region size).
3765   if (retained_region != NULL &&
3766       !retained_region->in_collection_set() &&
3767       !(retained_region->top() == retained_region->end()) &&
3768       !retained_region->is_empty() &&
3769       !retained_region->isHumongous()) {
3770     retained_region->set_saved_mark();
3771     _old_gc_alloc_region.set(retained_region);
3772     _hr_printer.reuse(retained_region);
3773   }
3774 }
3775 
3776 void G1CollectedHeap::release_gc_alloc_regions() {
3777   _survivor_gc_alloc_region.release();
3778   // If we have an old GC alloc region to release, we'll save it in
3779   // _retained_old_gc_alloc_region. If we don't
3780   // _retained_old_gc_alloc_region will become NULL. This is what we
3781   // want either way so no reason to check explicitly for either
3782   // condition.
3783   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
3784 }
3785 
3786 void G1CollectedHeap::abandon_gc_alloc_regions() {
3787   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
3788   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
3789   _retained_old_gc_alloc_region = NULL;
3790 }
3791 
3792 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3793   _drain_in_progress = false;
3794   set_evac_failure_closure(cl);
3795   _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3796 }
3797 
3798 void G1CollectedHeap::finalize_for_evac_failure() {
3799   assert(_evac_failure_scan_stack != NULL &&
3800          _evac_failure_scan_stack->length() == 0,
3801          "Postcondition");
3802   assert(!_drain_in_progress, "Postcondition");
3803   delete _evac_failure_scan_stack;
3804   _evac_failure_scan_stack = NULL;
3805 }
3806 
3807 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3808 private:
3809   G1CollectedHeap* _g1;
3810   DirtyCardQueue *_dcq;
3811   CardTableModRefBS* _ct_bs;
3812 
3813 public:
3814   UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3815     _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3816 
3817   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3818   virtual void do_oop(      oop* p) { do_oop_work(p); }
3819   template <class T> void do_oop_work(T* p) {
3820     assert(_from->is_in_reserved(p), "paranoia");
3821     if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3822         !_from->is_survivor()) {
3823       size_t card_index = _ct_bs->index_for(p);
3824       if (_ct_bs->mark_card_deferred(card_index)) {
3825         _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3826       }
3827     }
3828   }
3829 };
3830 
3831 class RemoveSelfPointerClosure: public ObjectClosure {
3832 private:
3833   G1CollectedHeap* _g1;
3834   ConcurrentMark* _cm;
3835   HeapRegion* _hr;
3836   size_t _prev_marked_bytes;
3837   size_t _next_marked_bytes;
3838   OopsInHeapRegionClosure *_cl;
3839 public:
3840   RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
3841                            OopsInHeapRegionClosure* cl) :
3842     _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()),  _prev_marked_bytes(0),
3843     _next_marked_bytes(0), _cl(cl) {}
3844 
3845   size_t prev_marked_bytes() { return _prev_marked_bytes; }
3846   size_t next_marked_bytes() { return _next_marked_bytes; }
3847 
3848   // <original comment>
3849   // The original idea here was to coalesce evacuated and dead objects.
3850   // However that caused complications with the block offset table (BOT).
3851   // In particular if there were two TLABs, one of them partially refined.
3852   // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3853   // The BOT entries of the unrefined part of TLAB_2 point to the start
3854   // of TLAB_2. If the last object of the TLAB_1 and the first object
3855   // of TLAB_2 are coalesced, then the cards of the unrefined part
3856   // would point into middle of the filler object.
3857   // The current approach is to not coalesce and leave the BOT contents intact.
3858   // </original comment>
3859   //
3860   // We now reset the BOT when we start the object iteration over the
3861   // region and refine its entries for every object we come across. So
3862   // the above comment is not really relevant and we should be able
3863   // to coalesce dead objects if we want to.
3864   void do_object(oop obj) {
3865     HeapWord* obj_addr = (HeapWord*) obj;
3866     assert(_hr->is_in(obj_addr), "sanity");
3867     size_t obj_size = obj->size();
3868     _hr->update_bot_for_object(obj_addr, obj_size);
3869     if (obj->is_forwarded() && obj->forwardee() == obj) {
3870       // The object failed to move.
3871       assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3872       _cm->markPrev(obj);
3873       assert(_cm->isPrevMarked(obj), "Should be marked!");
3874       _prev_marked_bytes += (obj_size * HeapWordSize);
3875       if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3876         _cm->markAndGrayObjectIfNecessary(obj);
3877       }
3878       obj->set_mark(markOopDesc::prototype());
3879       // While we were processing RSet buffers during the
3880       // collection, we actually didn't scan any cards on the
3881       // collection set, since we didn't want to update remebered
3882       // sets with entries that point into the collection set, given
3883       // that live objects fromthe collection set are about to move
3884       // and such entries will be stale very soon. This change also
3885       // dealt with a reliability issue which involved scanning a
3886       // card in the collection set and coming across an array that
3887       // was being chunked and looking malformed. The problem is
3888       // that, if evacuation fails, we might have remembered set
3889       // entries missing given that we skipped cards on the
3890       // collection set. So, we'll recreate such entries now.
3891       obj->oop_iterate(_cl);
3892       assert(_cm->isPrevMarked(obj), "Should be marked!");
3893     } else {
3894       // The object has been either evacuated or is dead. Fill it with a
3895       // dummy object.
3896       MemRegion mr((HeapWord*)obj, obj_size);
3897       CollectedHeap::fill_with_object(mr);
3898       _cm->clearRangeBothMaps(mr);
3899     }
3900   }
3901 };
3902 
3903 void G1CollectedHeap::remove_self_forwarding_pointers() {
3904   UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
3905   DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3906   UpdateRSetDeferred deferred_update(_g1h, &dcq);
3907   OopsInHeapRegionClosure *cl;
3908   if (G1DeferredRSUpdate) {
3909     cl = &deferred_update;
3910   } else {
3911     cl = &immediate_update;
3912   }
3913   HeapRegion* cur = g1_policy()->collection_set();
3914   while (cur != NULL) {
3915     assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3916     assert(!cur->isHumongous(), "sanity");
3917 
3918     if (cur->evacuation_failed()) {
3919       assert(cur->in_collection_set(), "bad CS");
3920       RemoveSelfPointerClosure rspc(_g1h, cur, cl);
3921 
3922       // In the common case we make sure that this is done when the
3923       // region is freed so that it is "ready-to-go" when it's
3924       // re-allocated. However, when evacuation failure happens, a
3925       // region will remain in the heap and might ultimately be added
3926       // to a CSet in the future. So we have to be careful here and
3927       // make sure the region's RSet is ready for parallel iteration
3928       // whenever this might be required in the future.
3929       cur->rem_set()->reset_for_par_iteration();
3930       cur->reset_bot();
3931       cl->set_region(cur);
3932       cur->object_iterate(&rspc);
3933 
3934       // A number of manipulations to make the TAMS be the current top,
3935       // and the marked bytes be the ones observed in the iteration.
3936       if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3937         // The comments below are the postconditions achieved by the
3938         // calls.  Note especially the last such condition, which says that
3939         // the count of marked bytes has been properly restored.
3940         cur->note_start_of_marking(false);
3941         // _next_top_at_mark_start == top, _next_marked_bytes == 0
3942         cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3943         // _next_marked_bytes == prev_marked_bytes.
3944         cur->note_end_of_marking();
3945         // _prev_top_at_mark_start == top(),
3946         // _prev_marked_bytes == prev_marked_bytes
3947       }
3948       // If there is no mark in progress, we modified the _next variables
3949       // above needlessly, but harmlessly.
3950       if (_g1h->mark_in_progress()) {
3951         cur->note_start_of_marking(false);
3952         // _next_top_at_mark_start == top, _next_marked_bytes == 0
3953         // _next_marked_bytes == next_marked_bytes.
3954       }
3955 
3956       // Now make sure the region has the right index in the sorted array.
3957       g1_policy()->note_change_in_marked_bytes(cur);
3958     }
3959     cur = cur->next_in_collection_set();
3960   }
3961   assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3962 
3963   // Now restore saved marks, if any.
3964   if (_objs_with_preserved_marks != NULL) {
3965     assert(_preserved_marks_of_objs != NULL, "Both or none.");
3966     guarantee(_objs_with_preserved_marks->length() ==
3967               _preserved_marks_of_objs->length(), "Both or none.");
3968     for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3969       oop obj   = _objs_with_preserved_marks->at(i);
3970       markOop m = _preserved_marks_of_objs->at(i);
3971       obj->set_mark(m);
3972     }
3973     // Delete the preserved marks growable arrays (allocated on the C heap).
3974     delete _objs_with_preserved_marks;
3975     delete _preserved_marks_of_objs;
3976     _objs_with_preserved_marks = NULL;
3977     _preserved_marks_of_objs = NULL;
3978   }
3979 }
3980 
3981 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3982   _evac_failure_scan_stack->push(obj);
3983 }
3984 
3985 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3986   assert(_evac_failure_scan_stack != NULL, "precondition");
3987 
3988   while (_evac_failure_scan_stack->length() > 0) {
3989      oop obj = _evac_failure_scan_stack->pop();
3990      _evac_failure_closure->set_region(heap_region_containing(obj));
3991      obj->oop_iterate_backwards(_evac_failure_closure);
3992   }
3993 }
3994 
3995 oop
3996 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3997                                                oop old,
3998                                                bool should_mark_root) {
3999   assert(obj_in_cs(old),
4000          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4001                  (HeapWord*) old));
4002   markOop m = old->mark();
4003   oop forward_ptr = old->forward_to_atomic(old);
4004   if (forward_ptr == NULL) {
4005     // Forward-to-self succeeded.
4006 
4007     // should_mark_root will be true when this routine is called
4008     // from a root scanning closure during an initial mark pause.
4009     // In this case the thread that succeeds in self-forwarding the
4010     // object is also responsible for marking the object.
4011     if (should_mark_root) {
4012       assert(!oopDesc::is_null(old), "shouldn't be");
4013       _cm->grayRoot(old);
4014     }
4015 
4016     if (_evac_failure_closure != cl) {
4017       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4018       assert(!_drain_in_progress,
4019              "Should only be true while someone holds the lock.");
4020       // Set the global evac-failure closure to the current thread's.
4021       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4022       set_evac_failure_closure(cl);
4023       // Now do the common part.
4024       handle_evacuation_failure_common(old, m);
4025       // Reset to NULL.
4026       set_evac_failure_closure(NULL);
4027     } else {
4028       // The lock is already held, and this is recursive.
4029       assert(_drain_in_progress, "This should only be the recursive case.");
4030       handle_evacuation_failure_common(old, m);
4031     }
4032     return old;
4033   } else {
4034     // Forward-to-self failed. Either someone else managed to allocate
4035     // space for this object (old != forward_ptr) or they beat us in
4036     // self-forwarding it (old == forward_ptr).
4037     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4038            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4039                    "should not be in the CSet",
4040                    (HeapWord*) old, (HeapWord*) forward_ptr));
4041     return forward_ptr;
4042   }
4043 }
4044 
4045 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4046   set_evacuation_failed(true);
4047 
4048   preserve_mark_if_necessary(old, m);
4049 
4050   HeapRegion* r = heap_region_containing(old);
4051   if (!r->evacuation_failed()) {
4052     r->set_evacuation_failed(true);
4053     _hr_printer.evac_failure(r);
4054   }
4055 
4056   push_on_evac_failure_scan_stack(old);
4057 
4058   if (!_drain_in_progress) {
4059     // prevent recursion in copy_to_survivor_space()
4060     _drain_in_progress = true;
4061     drain_evac_failure_scan_stack();
4062     _drain_in_progress = false;
4063   }
4064 }
4065 
4066 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4067   assert(evacuation_failed(), "Oversaving!");
4068   // We want to call the "for_promotion_failure" version only in the
4069   // case of a promotion failure.
4070   if (m->must_be_preserved_for_promotion_failure(obj)) {
4071     if (_objs_with_preserved_marks == NULL) {
4072       assert(_preserved_marks_of_objs == NULL, "Both or none.");
4073       _objs_with_preserved_marks =
4074         new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4075       _preserved_marks_of_objs =
4076         new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4077     }
4078     _objs_with_preserved_marks->push(obj);
4079     _preserved_marks_of_objs->push(m);
4080   }
4081 }
4082 
4083 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4084                                                   size_t word_size) {
4085   if (purpose == GCAllocForSurvived) {
4086     HeapWord* result = survivor_attempt_allocation(word_size);
4087     if (result != NULL) {
4088       return result;
4089     } else {
4090       // Let's try to allocate in the old gen in case we can fit the
4091       // object there.
4092       return old_attempt_allocation(word_size);
4093     }
4094   } else {
4095     assert(purpose ==  GCAllocForTenured, "sanity");
4096     HeapWord* result = old_attempt_allocation(word_size);
4097     if (result != NULL) {
4098       return result;
4099     } else {
4100       // Let's try to allocate in the survivors in case we can fit the
4101       // object there.
4102       return survivor_attempt_allocation(word_size);
4103     }
4104   }
4105 
4106   ShouldNotReachHere();
4107   // Trying to keep some compilers happy.
4108   return NULL;
4109 }
4110 
4111 #ifndef PRODUCT
4112 bool GCLabBitMapClosure::do_bit(size_t offset) {
4113   HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4114   guarantee(_cm->isMarked(oop(addr)), "it should be!");
4115   return true;
4116 }
4117 #endif // PRODUCT
4118 
4119 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4120   ParGCAllocBuffer(gclab_word_size),
4121   _should_mark_objects(false),
4122   _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
4123   _retired(false)
4124 {
4125   //_should_mark_objects is set to true when G1ParCopyHelper needs to
4126   // mark the forwarded location of an evacuated object.
4127   // We set _should_mark_objects to true if marking is active, i.e. when we
4128   // need to propagate a mark, or during an initial mark pause, i.e. when we
4129   // need to mark objects immediately reachable by the roots.
4130   if (G1CollectedHeap::heap()->mark_in_progress() ||
4131       G1CollectedHeap::heap()->g1_policy()->during_initial_mark_pause()) {
4132     _should_mark_objects = true;
4133   }
4134 }
4135 
4136 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4137   : _g1h(g1h),
4138     _refs(g1h->task_queue(queue_num)),
4139     _dcq(&g1h->dirty_card_queue_set()),
4140     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4141     _g1_rem(g1h->g1_rem_set()),
4142     _hash_seed(17), _queue_num(queue_num),
4143     _term_attempts(0),
4144     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4145     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4146     _age_table(false),
4147     _strong_roots_time(0), _term_time(0),
4148     _alloc_buffer_waste(0), _undo_waste(0)
4149 {
4150   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4151   // we "sacrifice" entry 0 to keep track of surviving bytes for
4152   // non-young regions (where the age is -1)
4153   // We also add a few elements at the beginning and at the end in
4154   // an attempt to eliminate cache contention
4155   size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
4156   size_t array_length = PADDING_ELEM_NUM +
4157                         real_length +
4158                         PADDING_ELEM_NUM;
4159   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4160   if (_surviving_young_words_base == NULL)
4161     vm_exit_out_of_memory(array_length * sizeof(size_t),
4162                           "Not enough space for young surv histo.");
4163   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4164   memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4165 
4166   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4167   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4168 
4169   _start = os::elapsedTime();
4170 }
4171 
4172 void
4173 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4174 {
4175   st->print_raw_cr("GC Termination Stats");
4176   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4177                    " ------waste (KiB)------");
4178   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4179                    "  total   alloc    undo");
4180   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4181                    " ------- ------- -------");
4182 }
4183 
4184 void
4185 G1ParScanThreadState::print_termination_stats(int i,
4186                                               outputStream* const st) const
4187 {
4188   const double elapsed_ms = elapsed_time() * 1000.0;
4189   const double s_roots_ms = strong_roots_time() * 1000.0;
4190   const double term_ms    = term_time() * 1000.0;
4191   st->print_cr("%3d %9.2f %9.2f %6.2f "
4192                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4193                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4194                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4195                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4196                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4197                alloc_buffer_waste() * HeapWordSize / K,
4198                undo_waste() * HeapWordSize / K);
4199 }
4200 
4201 #ifdef ASSERT
4202 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4203   assert(ref != NULL, "invariant");
4204   assert(UseCompressedOops, "sanity");
4205   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4206   oop p = oopDesc::load_decode_heap_oop(ref);
4207   assert(_g1h->is_in_g1_reserved(p),
4208          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4209   return true;
4210 }
4211 
4212 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4213   assert(ref != NULL, "invariant");
4214   if (has_partial_array_mask(ref)) {
4215     // Must be in the collection set--it's already been copied.
4216     oop p = clear_partial_array_mask(ref);
4217     assert(_g1h->obj_in_cs(p),
4218            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4219   } else {
4220     oop p = oopDesc::load_decode_heap_oop(ref);
4221     assert(_g1h->is_in_g1_reserved(p),
4222            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4223   }
4224   return true;
4225 }
4226 
4227 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4228   if (ref.is_narrow()) {
4229     return verify_ref((narrowOop*) ref);
4230   } else {
4231     return verify_ref((oop*) ref);
4232   }
4233 }
4234 #endif // ASSERT
4235 
4236 void G1ParScanThreadState::trim_queue() {
4237   assert(_evac_cl != NULL, "not set");
4238   assert(_evac_failure_cl != NULL, "not set");
4239   assert(_partial_scan_cl != NULL, "not set");
4240 
4241   StarTask ref;
4242   do {
4243     // Drain the overflow stack first, so other threads can steal.
4244     while (refs()->pop_overflow(ref)) {
4245       deal_with_reference(ref);
4246     }
4247 
4248     while (refs()->pop_local(ref)) {
4249       deal_with_reference(ref);
4250     }
4251   } while (!refs()->is_empty());
4252 }
4253 
4254 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4255   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4256   _par_scan_state(par_scan_state),
4257   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4258   _mark_in_progress(_g1->mark_in_progress()) { }
4259 
4260 template <class T> void G1ParCopyHelper::mark_object(T* p) {
4261   // This is called from do_oop_work for objects that are not
4262   // in the collection set. Objects in the collection set
4263   // are marked after they have been evacuated.
4264 
4265   T heap_oop = oopDesc::load_heap_oop(p);
4266   if (!oopDesc::is_null(heap_oop)) {
4267     oop obj = oopDesc::decode_heap_oop(heap_oop);
4268     HeapWord* addr = (HeapWord*)obj;
4269     if (_g1->is_in_g1_reserved(addr)) {
4270       _cm->grayRoot(oop(addr));
4271     }
4272   }
4273 }
4274 
4275 oop G1ParCopyHelper::copy_to_survivor_space(oop old, bool should_mark_root,
4276                                                      bool should_mark_copy) {
4277   size_t    word_sz = old->size();
4278   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4279   // +1 to make the -1 indexes valid...
4280   int       young_index = from_region->young_index_in_cset()+1;
4281   assert( (from_region->is_young() && young_index > 0) ||
4282           (!from_region->is_young() && young_index == 0), "invariant" );
4283   G1CollectorPolicy* g1p = _g1->g1_policy();
4284   markOop m = old->mark();
4285   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4286                                            : m->age();
4287   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4288                                                              word_sz);
4289   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4290   oop       obj     = oop(obj_ptr);
4291 
4292   if (obj_ptr == NULL) {
4293     // This will either forward-to-self, or detect that someone else has
4294     // installed a forwarding pointer.
4295     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4296     return _g1->handle_evacuation_failure_par(cl, old, should_mark_root);
4297   }
4298 
4299   // We're going to allocate linearly, so might as well prefetch ahead.
4300   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4301 
4302   oop forward_ptr = old->forward_to_atomic(obj);
4303   if (forward_ptr == NULL) {
4304     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4305     if (g1p->track_object_age(alloc_purpose)) {
4306       // We could simply do obj->incr_age(). However, this causes a
4307       // performance issue. obj->incr_age() will first check whether
4308       // the object has a displaced mark by checking its mark word;
4309       // getting the mark word from the new location of the object
4310       // stalls. So, given that we already have the mark word and we
4311       // are about to install it anyway, it's better to increase the
4312       // age on the mark word, when the object does not have a
4313       // displaced mark word. We're not expecting many objects to have
4314       // a displaced marked word, so that case is not optimized
4315       // further (it could be...) and we simply call obj->incr_age().
4316 
4317       if (m->has_displaced_mark_helper()) {
4318         // in this case, we have to install the mark word first,
4319         // otherwise obj looks to be forwarded (the old mark word,
4320         // which contains the forward pointer, was copied)
4321         obj->set_mark(m);
4322         obj->incr_age();
4323       } else {
4324         m = m->incr_age();
4325         obj->set_mark(m);
4326       }
4327       _par_scan_state->age_table()->add(obj, word_sz);
4328     } else {
4329       obj->set_mark(m);
4330     }
4331 
4332     // Mark the evacuated object or propagate "next" mark bit
4333     if (should_mark_copy) {
4334       if (!use_local_bitmaps ||
4335           !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4336         // if we couldn't mark it on the local bitmap (this happens when
4337         // the object was not allocated in the GCLab), we have to bite
4338         // the bullet and do the standard parallel mark
4339         _cm->markAndGrayObjectIfNecessary(obj);
4340       }
4341 
4342       if (_g1->isMarkedNext(old)) {
4343         // Unmark the object's old location so that marking
4344         // doesn't think the old object is alive.
4345         _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4346       }
4347     }
4348 
4349     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4350     surv_young_words[young_index] += word_sz;
4351 
4352     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4353       arrayOop(old)->set_length(0);
4354       oop* old_p = set_partial_array_mask(old);
4355       _par_scan_state->push_on_queue(old_p);
4356     } else {
4357       // No point in using the slower heap_region_containing() method,
4358       // given that we know obj is in the heap.
4359       _scanner->set_region(_g1->heap_region_containing_raw(obj));
4360       obj->oop_iterate_backwards(_scanner);
4361     }
4362   } else {
4363     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4364     obj = forward_ptr;
4365   }
4366   return obj;
4367 }
4368 
4369 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4370 template <class T>
4371 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4372 ::do_oop_work(T* p) {
4373   oop obj = oopDesc::load_decode_heap_oop(p);
4374   assert(barrier != G1BarrierRS || obj != NULL,
4375          "Precondition: G1BarrierRS implies obj is nonNull");
4376 
4377   // Marking:
4378   // If the object is in the collection set, then the thread
4379   // that copies the object should mark, or propagate the
4380   // mark to, the evacuated object.
4381   // If the object is not in the collection set then we
4382   // should call the mark_object() method depending on the
4383   // value of the template parameter do_mark_object (which will
4384   // be true for root scanning closures during an initial mark
4385   // pause).
4386   // The mark_object() method first checks whether the object
4387   // is marked and, if not, attempts to mark the object.
4388 
4389   // here the null check is implicit in the cset_fast_test() test
4390   if (_g1->in_cset_fast_test(obj)) {
4391     if (obj->is_forwarded()) {
4392       oopDesc::encode_store_heap_oop(p, obj->forwardee());
4393       // If we are a root scanning closure during an initial
4394       // mark pause (i.e. do_mark_object will be true) then
4395       // we also need to handle marking of roots in the
4396       // event of an evacuation failure. In the event of an
4397       // evacuation failure, the object is forwarded to itself
4398       // and not copied. For root-scanning closures, the
4399       // object would be marked after a successful self-forward
4400       // but an object could be pointed to by both a root and non
4401       // root location and be self-forwarded by a non-root-scanning
4402       // closure. Therefore we also have to attempt to mark the
4403       // self-forwarded root object here.
4404       if (do_mark_object && obj->forwardee() == obj) {
4405         mark_object(p);
4406       }
4407     } else {
4408       // During an initial mark pause, objects that are pointed to
4409       // by the roots need to be marked - even in the event of an
4410       // evacuation failure. We pass the template parameter
4411       // do_mark_object (which is true for root scanning closures
4412       // during an initial mark pause) to copy_to_survivor_space
4413       // which will pass it on to the evacuation failure handling
4414       // code. The thread that successfully self-forwards a root
4415       // object to itself is responsible for marking the object.
4416       bool should_mark_root = do_mark_object;
4417 
4418       // We need to mark the copied object if we're a root scanning
4419       // closure during an initial mark pause (i.e. do_mark_object
4420       // will be true), or the object is already marked and we need
4421       // to propagate the mark to the evacuated copy.
4422       bool should_mark_copy = do_mark_object ||
4423                               _during_initial_mark ||
4424                               (_mark_in_progress && !_g1->is_obj_ill(obj));
4425 
4426       oop copy_oop = copy_to_survivor_space(obj, should_mark_root,
4427                                                  should_mark_copy);
4428       oopDesc::encode_store_heap_oop(p, copy_oop);
4429     }
4430     // When scanning the RS, we only care about objs in CS.
4431     if (barrier == G1BarrierRS) {
4432       _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4433     }
4434   } else {
4435     // The object is not in collection set. If we're a root scanning
4436     // closure during an initial mark pause (i.e. do_mark_object will
4437     // be true) then attempt to mark the object.
4438     if (do_mark_object) {
4439       mark_object(p);
4440     }
4441   }
4442 
4443   if (barrier == G1BarrierEvac && obj != NULL) {
4444     _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4445   }
4446 
4447   if (do_gen_barrier && obj != NULL) {
4448     par_do_barrier(p);
4449   }
4450 }
4451 
4452 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4453 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4454 
4455 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4456   assert(has_partial_array_mask(p), "invariant");
4457   oop old = clear_partial_array_mask(p);
4458   assert(old->is_objArray(), "must be obj array");
4459   assert(old->is_forwarded(), "must be forwarded");
4460   assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4461 
4462   objArrayOop obj = objArrayOop(old->forwardee());
4463   assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4464   // Process ParGCArrayScanChunk elements now
4465   // and push the remainder back onto queue
4466   int start     = arrayOop(old)->length();
4467   int end       = obj->length();
4468   int remainder = end - start;
4469   assert(start <= end, "just checking");
4470   if (remainder > 2 * ParGCArrayScanChunk) {
4471     // Test above combines last partial chunk with a full chunk
4472     end = start + ParGCArrayScanChunk;
4473     arrayOop(old)->set_length(end);
4474     // Push remainder.
4475     oop* old_p = set_partial_array_mask(old);
4476     assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4477     _par_scan_state->push_on_queue(old_p);
4478   } else {
4479     // Restore length so that the heap remains parsable in
4480     // case of evacuation failure.
4481     arrayOop(old)->set_length(end);
4482   }
4483   _scanner.set_region(_g1->heap_region_containing_raw(obj));
4484   // process our set of indices (include header in first chunk)
4485   obj->oop_iterate_range(&_scanner, start, end);
4486 }
4487 
4488 class G1ParEvacuateFollowersClosure : public VoidClosure {
4489 protected:
4490   G1CollectedHeap*              _g1h;
4491   G1ParScanThreadState*         _par_scan_state;
4492   RefToScanQueueSet*            _queues;
4493   ParallelTaskTerminator*       _terminator;
4494 
4495   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4496   RefToScanQueueSet*      queues()         { return _queues; }
4497   ParallelTaskTerminator* terminator()     { return _terminator; }
4498 
4499 public:
4500   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4501                                 G1ParScanThreadState* par_scan_state,
4502                                 RefToScanQueueSet* queues,
4503                                 ParallelTaskTerminator* terminator)
4504     : _g1h(g1h), _par_scan_state(par_scan_state),
4505       _queues(queues), _terminator(terminator) {}
4506 
4507   void do_void();
4508 
4509 private:
4510   inline bool offer_termination();
4511 };
4512 
4513 bool G1ParEvacuateFollowersClosure::offer_termination() {
4514   G1ParScanThreadState* const pss = par_scan_state();
4515   pss->start_term_time();
4516   const bool res = terminator()->offer_termination();
4517   pss->end_term_time();
4518   return res;
4519 }
4520 
4521 void G1ParEvacuateFollowersClosure::do_void() {
4522   StarTask stolen_task;
4523   G1ParScanThreadState* const pss = par_scan_state();
4524   pss->trim_queue();
4525 
4526   do {
4527     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4528       assert(pss->verify_task(stolen_task), "sanity");
4529       if (stolen_task.is_narrow()) {
4530         pss->deal_with_reference((narrowOop*) stolen_task);
4531       } else {
4532         pss->deal_with_reference((oop*) stolen_task);
4533       }
4534 
4535       // We've just processed a reference and we might have made
4536       // available new entries on the queues. So we have to make sure
4537       // we drain the queues as necessary.
4538       pss->trim_queue();
4539     }
4540   } while (!offer_termination());
4541 
4542   pss->retire_alloc_buffers();
4543 }
4544 
4545 class G1ParTask : public AbstractGangTask {
4546 protected:
4547   G1CollectedHeap*       _g1h;
4548   RefToScanQueueSet      *_queues;
4549   ParallelTaskTerminator _terminator;
4550   int _n_workers;
4551 
4552   Mutex _stats_lock;
4553   Mutex* stats_lock() { return &_stats_lock; }
4554 
4555   size_t getNCards() {
4556     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4557       / G1BlockOffsetSharedArray::N_bytes;
4558   }
4559 
4560 public:
4561   G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4562     : AbstractGangTask("G1 collection"),
4563       _g1h(g1h),
4564       _queues(task_queues),
4565       _terminator(workers, _queues),
4566       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4567       _n_workers(workers)
4568   {}
4569 
4570   RefToScanQueueSet* queues() { return _queues; }
4571 
4572   RefToScanQueue *work_queue(int i) {
4573     return queues()->queue(i);
4574   }
4575 
4576   void work(int i) {
4577     if (i >= _n_workers) return;  // no work needed this round
4578 
4579     double start_time_ms = os::elapsedTime() * 1000.0;
4580     _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4581 
4582     ResourceMark rm;
4583     HandleMark   hm;
4584 
4585     ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4586 
4587     G1ParScanThreadState            pss(_g1h, i);
4588     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
4589     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4590     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
4591 
4592     pss.set_evac_closure(&scan_evac_cl);
4593     pss.set_evac_failure_closure(&evac_failure_cl);
4594     pss.set_partial_scan_closure(&partial_scan_cl);
4595 
4596     G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4597     G1ParScanPermClosure           only_scan_perm_cl(_g1h, &pss, rp);
4598 
4599     G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4600     G1ParScanAndMarkPermClosure    scan_mark_perm_cl(_g1h, &pss, rp);
4601 
4602     OopClosure*                    scan_root_cl = &only_scan_root_cl;
4603     OopsInHeapRegionClosure*       scan_perm_cl = &only_scan_perm_cl;
4604 
4605     if (_g1h->g1_policy()->during_initial_mark_pause()) {
4606       // We also need to mark copied objects.
4607       scan_root_cl = &scan_mark_root_cl;
4608       scan_perm_cl = &scan_mark_perm_cl;
4609     }
4610 
4611     // The following closure is used to scan RSets looking for reference
4612     // fields that point into the collection set. The actual field iteration
4613     // is performed by a FilterIntoCSClosure, whose do_oop method calls the
4614     // do_oop method of the following closure.
4615     // Therefore we want to record the reference processor in the
4616     // FilterIntoCSClosure. To do so we record the STW reference
4617     // processor into the following closure and pass it to the
4618     // FilterIntoCSClosure in HeapRegionDCTOC::walk_mem_region_with_cl.
4619     G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss, rp);
4620 
4621     pss.start_strong_roots();
4622     _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4623                                   SharedHeap::SO_AllClasses,
4624                                   scan_root_cl,
4625                                   &push_heap_rs_cl,
4626                                   scan_perm_cl,
4627                                   i);
4628     pss.end_strong_roots();
4629 
4630     {
4631       double start = os::elapsedTime();
4632       G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4633       evac.do_void();
4634       double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4635       double term_ms = pss.term_time()*1000.0;
4636       _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4637       _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4638     }
4639     _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4640     _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4641 
4642     // Clean up any par-expanded rem sets.
4643     HeapRegionRemSet::par_cleanup();
4644 
4645     if (ParallelGCVerbose) {
4646       MutexLocker x(stats_lock());
4647       pss.print_termination_stats(i);
4648     }
4649 
4650     assert(pss.refs()->is_empty(), "should be empty");
4651     double end_time_ms = os::elapsedTime() * 1000.0;
4652     _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4653   }
4654 };
4655 
4656 // *** Common G1 Evacuation Stuff
4657 
4658 // This method is run in a GC worker.
4659 
4660 void
4661 G1CollectedHeap::
4662 g1_process_strong_roots(bool collecting_perm_gen,
4663                         SharedHeap::ScanningOption so,
4664                         OopClosure* scan_non_heap_roots,
4665                         OopsInHeapRegionClosure* scan_rs,
4666                         OopsInGenClosure* scan_perm,
4667                         int worker_i) {
4668 
4669   // First scan the strong roots, including the perm gen.
4670   double ext_roots_start = os::elapsedTime();
4671   double closure_app_time_sec = 0.0;
4672 
4673   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4674   BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4675   buf_scan_perm.set_generation(perm_gen());
4676 
4677   // Walk the code cache w/o buffering, because StarTask cannot handle
4678   // unaligned oop locations.
4679   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4680 
4681   process_strong_roots(false, // no scoping; this is parallel code
4682                        collecting_perm_gen, so,
4683                        &buf_scan_non_heap_roots,
4684                        &eager_scan_code_roots,
4685                        &buf_scan_perm);
4686 
4687   // Now the CM ref_processor roots.
4688   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4689     // We need to treat the discovered reference lists of the
4690     // concurrent mark ref processor as roots and keep entries
4691     // (which are added by the marking threads) on them live
4692     // until they can be processed at the end of marking.
4693     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4694   }
4695 
4696   // Finish up any enqueued closure apps (attributed as object copy time).
4697   buf_scan_non_heap_roots.done();
4698   buf_scan_perm.done();
4699 
4700   double ext_roots_end = os::elapsedTime();
4701 
4702   g1_policy()->reset_obj_copy_time(worker_i);
4703   double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4704                                 buf_scan_non_heap_roots.closure_app_seconds();
4705   g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4706 
4707   double ext_root_time_ms =
4708     ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4709 
4710   g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4711 
4712   // Scan strong roots in mark stack.
4713   if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4714     concurrent_mark()->oops_do(scan_non_heap_roots);
4715   }
4716   double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4717   g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4718 
4719   // Now scan the complement of the collection set.
4720   if (scan_rs != NULL) {
4721     g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4722   }
4723 
4724   _process_strong_tasks->all_tasks_completed();
4725 }
4726 
4727 void
4728 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4729                                        OopClosure* non_root_closure) {
4730   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4731   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4732 }
4733 
4734 // Weak Reference Processing support
4735 
4736 // An always "is_alive" closure that is used to preserve referents.
4737 // If the object is non-null then it's alive.  Used in the preservation
4738 // of referent objects that are pointed to by reference objects
4739 // discovered by the CM ref processor.
4740 class G1AlwaysAliveClosure: public BoolObjectClosure {
4741   G1CollectedHeap* _g1;
4742 public:
4743   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4744   void do_object(oop p) { assert(false, "Do not call."); }
4745   bool do_object_b(oop p) {
4746     if (p != NULL) {
4747       return true;
4748     }
4749     return false;
4750   }
4751 };
4752 
4753 bool G1STWIsAliveClosure::do_object_b(oop p) {
4754   // An object is reachable if it is outside the collection set,
4755   // or is inside and copied.
4756   return !_g1->obj_in_cs(p) || p->is_forwarded();
4757 }
4758 
4759 // Non Copying Keep Alive closure
4760 class G1KeepAliveClosure: public OopClosure {
4761   G1CollectedHeap* _g1;
4762 public:
4763   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4764   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4765   void do_oop(      oop* p) {
4766     oop obj = *p;
4767 
4768     if (_g1->obj_in_cs(obj)) {
4769       assert( obj->is_forwarded(), "invariant" );
4770       *p = obj->forwardee();
4771     }
4772   }
4773 };
4774 
4775 // Copying Keep Alive closure - can be called from both
4776 // serial and parallel code as long as different worker
4777 // threads utilize different G1ParScanThreadState instances
4778 // and different queues.
4779 
4780 class G1CopyingKeepAliveClosure: public OopClosure {
4781   G1CollectedHeap*         _g1h;
4782   OopClosure*              _copy_non_heap_obj_cl;
4783   OopsInHeapRegionClosure* _copy_perm_obj_cl;
4784   G1ParScanThreadState*    _par_scan_state;
4785 
4786 public:
4787   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4788                             OopClosure* non_heap_obj_cl,
4789                             OopsInHeapRegionClosure* perm_obj_cl,
4790                             G1ParScanThreadState* pss):
4791     _g1h(g1h),
4792     _copy_non_heap_obj_cl(non_heap_obj_cl),
4793     _copy_perm_obj_cl(perm_obj_cl),
4794     _par_scan_state(pss)
4795   {}
4796 
4797   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4798   virtual void do_oop(      oop* p) { do_oop_work(p); }
4799 
4800   template <class T> void do_oop_work(T* p) {
4801     oop obj = oopDesc::load_decode_heap_oop(p);
4802 
4803     if (_g1h->obj_in_cs(obj)) {
4804       // If the referent object has been forwarded (either copied
4805       // to a new location or to itself in the event of an
4806       // evacuation failure) then we need to update the reference
4807       // field and, if both reference and referent are in the G1
4808       // heap, update the RSet for the referent.
4809       //
4810       // If the referent has not been forwarded then we have to keep
4811       // it alive by policy. Therefore we have copy the referent.
4812       //
4813       // If the reference field is in the G1 heap then we can push
4814       // on the PSS queue. When the queue is drained (after each
4815       // phase of reference processing) the object and it's followers
4816       // will be copied, the reference field set to point to the
4817       // new location, and the RSet updated. Otherwise we need to
4818       // use the the non-heap or perm closures directly to copy
4819       // the refernt object and update the pointer, while avoiding
4820       // updating the RSet.
4821 
4822       if (_g1h->is_in_g1_reserved(p)) {
4823         _par_scan_state->push_on_queue(p);
4824       } else {
4825         // The reference field is not in the G1 heap.
4826         if (_g1h->perm_gen()->is_in(p)) {
4827           _copy_perm_obj_cl->do_oop(p);
4828         } else {
4829           _copy_non_heap_obj_cl->do_oop(p);
4830         }
4831       }
4832     }
4833   }
4834 };
4835 
4836 // Serial drain queue closure. Called as the 'complete_gc'
4837 // closure for each discovered list in some of the
4838 // reference processing phases.
4839 
4840 class G1STWDrainQueueClosure: public VoidClosure {
4841 protected:
4842   G1CollectedHeap* _g1h;
4843   G1ParScanThreadState* _par_scan_state;
4844 
4845   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4846 
4847 public:
4848   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4849     _g1h(g1h),
4850     _par_scan_state(pss)
4851   { }
4852 
4853   void do_void() {
4854     G1ParScanThreadState* const pss = par_scan_state();
4855     pss->trim_queue();
4856   }
4857 };
4858 
4859 // Parallel Reference Processing closures
4860 
4861 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4862 // processing during G1 evacuation pauses.
4863 
4864 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4865 private:
4866   G1CollectedHeap*   _g1h;
4867   RefToScanQueueSet* _queues;
4868   WorkGang*          _workers;
4869   int                _active_workers;
4870 
4871 public:
4872   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4873                         WorkGang* workers,
4874                         RefToScanQueueSet *task_queues,
4875                         int n_workers) :
4876     _g1h(g1h),
4877     _queues(task_queues),
4878     _workers(workers),
4879     _active_workers(n_workers)
4880   {
4881     assert(n_workers > 0, "shouldn't call this otherwise");
4882   }
4883 
4884   // Executes the given task using concurrent marking worker threads.
4885   virtual void execute(ProcessTask& task);
4886   virtual void execute(EnqueueTask& task);
4887 };
4888 
4889 // Gang task for possibly parallel reference processing
4890 
4891 class G1STWRefProcTaskProxy: public AbstractGangTask {
4892   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4893   ProcessTask&     _proc_task;
4894   G1CollectedHeap* _g1h;
4895   RefToScanQueueSet *_task_queues;
4896   ParallelTaskTerminator* _terminator;
4897 
4898 public:
4899   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4900                      G1CollectedHeap* g1h,
4901                      RefToScanQueueSet *task_queues,
4902                      ParallelTaskTerminator* terminator) :
4903     AbstractGangTask("Process reference objects in parallel"),
4904     _proc_task(proc_task),
4905     _g1h(g1h),
4906     _task_queues(task_queues),
4907     _terminator(terminator)
4908   {}
4909 
4910   virtual void work(int i) {
4911     // The reference processing task executed by a single worker.
4912     ResourceMark rm;
4913     HandleMark   hm;
4914 
4915     G1STWIsAliveClosure is_alive(_g1h);
4916 
4917     G1ParScanThreadState pss(_g1h, i);
4918 
4919     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
4920     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
4921     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
4922 
4923     pss.set_evac_closure(&scan_evac_cl);
4924     pss.set_evac_failure_closure(&evac_failure_cl);
4925     pss.set_partial_scan_closure(&partial_scan_cl);
4926 
4927     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
4928     G1ParScanPermClosure           only_copy_perm_cl(_g1h, &pss, NULL);
4929 
4930     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
4931     G1ParScanAndMarkPermClosure    copy_mark_perm_cl(_g1h, &pss, NULL);
4932 
4933     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
4934     OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
4935 
4936     if (_g1h->g1_policy()->during_initial_mark_pause()) {
4937       // We also need to mark copied objects.
4938       copy_non_heap_cl = &copy_mark_non_heap_cl;
4939       copy_perm_cl = &copy_mark_perm_cl;
4940     }
4941 
4942     // Keep alive closure.
4943     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
4944 
4945     // Complete GC closure
4946     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
4947 
4948     // Call the reference processing task's work routine.
4949     _proc_task.work(i, is_alive, keep_alive, drain_queue);
4950 
4951     // Note we cannot assert that the refs array is empty here as not all
4952     // of the processing tasks (specifically phase2 - pp2_work) execute
4953     // the complete_gc closure (which ordinarily would drain the queue) so
4954     // the queue may not be empty.
4955   }
4956 };
4957 
4958 // Driver routine for parallel reference processing.
4959 // Creates an instance of the ref processing gang
4960 // task and has the worker threads execute it.
4961 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4962   assert(_workers != NULL, "Need parallel worker threads.");
4963 
4964   ParallelTaskTerminator terminator(_active_workers, _queues);
4965   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
4966 
4967   _g1h->set_par_threads(_active_workers);
4968   _workers->run_task(&proc_task_proxy);
4969   _g1h->set_par_threads(0);
4970 }
4971 
4972 // Gang task for parallel reference enqueueing.
4973 
4974 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4975   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4976   EnqueueTask& _enq_task;
4977 
4978 public:
4979   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4980     AbstractGangTask("Enqueue reference objects in parallel"),
4981     _enq_task(enq_task)
4982   { }
4983 
4984   virtual void work(int i) {
4985     _enq_task.work(i);
4986   }
4987 };
4988 
4989 // Driver routine for parallel reference enqueing.
4990 // Creates an instance of the ref enqueueing gang
4991 // task and has the worker threads execute it.
4992 
4993 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4994   assert(_workers != NULL, "Need parallel worker threads.");
4995 
4996   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4997 
4998   _g1h->set_par_threads(_active_workers);
4999   _workers->run_task(&enq_task_proxy);
5000   _g1h->set_par_threads(0);
5001 }
5002 
5003 // End of weak reference support closures
5004 
5005 // Abstract task used to preserve (i.e. copy) any referent objects
5006 // that are in the collection set and are pointed to by reference
5007 // objects discovered by the CM ref processor.
5008 
5009 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5010 protected:
5011   G1CollectedHeap* _g1h;
5012   RefToScanQueueSet      *_queues;
5013   ParallelTaskTerminator _terminator;
5014   int _n_workers;
5015 
5016 public:
5017   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5018     AbstractGangTask("ParPreserveCMReferents"),
5019     _g1h(g1h),
5020     _queues(task_queues),
5021     _terminator(workers, _queues),
5022     _n_workers(workers)
5023   { }
5024 
5025   void work(int i) {
5026     ResourceMark rm;
5027     HandleMark   hm;
5028 
5029     G1ParScanThreadState            pss(_g1h, i);
5030     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5031     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5032     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5033 
5034     pss.set_evac_closure(&scan_evac_cl);
5035     pss.set_evac_failure_closure(&evac_failure_cl);
5036     pss.set_partial_scan_closure(&partial_scan_cl);
5037 
5038     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5039 
5040 
5041     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5042     G1ParScanPermClosure           only_copy_perm_cl(_g1h, &pss, NULL);
5043 
5044     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5045     G1ParScanAndMarkPermClosure    copy_mark_perm_cl(_g1h, &pss, NULL);
5046 
5047     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5048     OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
5049 
5050     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5051       // We also need to mark copied objects.
5052       copy_non_heap_cl = &copy_mark_non_heap_cl;
5053       copy_perm_cl = &copy_mark_perm_cl;
5054     }
5055 
5056     // Is alive closure
5057     G1AlwaysAliveClosure always_alive(_g1h);
5058 
5059     // Copying keep alive closure. Applied to referent objects that need
5060     // to be copied.
5061     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5062 
5063     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5064 
5065     int limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5066     int stride = MIN2(MAX2(_n_workers, 1), limit);
5067 
5068     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5069     // So this must be true - but assert just in case someone decides to
5070     // change the worker ids.
5071     assert(0 <= i && i < limit, "sanity");
5072     assert(!rp->discovery_is_atomic(), "check this code");
5073 
5074     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5075     for (int idx = i; idx < limit; idx += stride) {
5076       DiscoveredList& ref_list = rp->discovered_soft_refs()[idx];
5077 
5078       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5079       while (iter.has_next()) {
5080         // Since discovery is not atomic for the CM ref processor, we
5081         // can see some null referent objects.
5082         iter.load_ptrs(DEBUG_ONLY(true));
5083         oop ref = iter.obj();
5084 
5085         // This will filter nulls.
5086         if (iter.is_referent_alive()) {
5087           iter.make_referent_alive();
5088         }
5089         iter.move_to_next();
5090       }
5091     }
5092 
5093     // Drain the queue - which may cause stealing
5094     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5095     drain_queue.do_void();
5096     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5097     assert(pss.refs()->is_empty(), "should be");
5098   }
5099 };
5100 
5101 // Weak Reference processing during an evacuation pause (part 1).
5102 void G1CollectedHeap::process_discovered_references() {
5103   double ref_proc_start = os::elapsedTime();
5104 
5105   ReferenceProcessor* rp = _ref_processor_stw;
5106   assert(rp->discovery_enabled(), "should have been enabled");
5107 
5108   // Any reference objects, in the collection set, that were 'discovered'
5109   // by the CM ref processor should have already been copied (either by
5110   // applying the external root copy closure to the discovered lists, or
5111   // by following an RSet entry).
5112   //
5113   // But some of the referents, that are in the collection set, that these
5114   // reference objects point to may not have been copied: the STW ref
5115   // processor would have seen that the reference object had already
5116   // been 'discovered' and would have skipped discovering the reference,
5117   // but would not have treated the reference object as a regular oop.
5118   // As a reult the copy closure would not have been applied to the
5119   // referent object.
5120   //
5121   // We need to explicitly copy these referent objects - the references
5122   // will be processed at the end of remarking.
5123   //
5124   // We also need to do this copying before we process the reference
5125   // objects discovered by the STW ref processor in case one of these
5126   // referents points to another object which is also referenced by an
5127   // object discovered by the STW ref processor.
5128 
5129   int n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5130                         workers()->total_workers() : 1);
5131 
5132   set_par_threads(n_workers);
5133   G1ParPreserveCMReferentsTask keep_cm_referents(this, n_workers, _task_queues);
5134 
5135   if (G1CollectedHeap::use_parallel_gc_threads()) {
5136     workers()->run_task(&keep_cm_referents);
5137   } else {
5138     keep_cm_referents.work(0);
5139   }
5140 
5141   set_par_threads(0);
5142 
5143   // Closure to test whether a referent is alive.
5144   G1STWIsAliveClosure is_alive(this);
5145 
5146   // Even when parallel reference processing is enabled, the processing
5147   // of JNI refs is serial and performed serially by the current thread
5148   // rather than by a worker. The following PSS will be used for processing
5149   // JNI refs.
5150 
5151   // Use only a single queue for this PSS.
5152   G1ParScanThreadState pss(this, 0);
5153 
5154   // We do not embed a reference processor in the copying/scanning
5155   // closures while we're actually processing the discovered
5156   // reference objects.
5157   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5158   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5159   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5160 
5161   pss.set_evac_closure(&scan_evac_cl);
5162   pss.set_evac_failure_closure(&evac_failure_cl);
5163   pss.set_partial_scan_closure(&partial_scan_cl);
5164 
5165   assert(pss.refs()->is_empty(), "pre-condition");
5166 
5167   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5168   G1ParScanPermClosure           only_copy_perm_cl(this, &pss, NULL);
5169 
5170   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5171   G1ParScanAndMarkPermClosure    copy_mark_perm_cl(this, &pss, NULL);
5172 
5173   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5174   OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
5175 
5176   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5177     // We also need to mark copied objects.
5178     copy_non_heap_cl = &copy_mark_non_heap_cl;
5179     copy_perm_cl = &copy_mark_perm_cl;
5180   }
5181 
5182   // Keep alive closure.
5183   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5184 
5185   // Serial Complete GC closure
5186   G1STWDrainQueueClosure drain_queue(this, &pss);
5187 
5188   // Setup the soft refs policy...
5189   rp->setup_policy(false);
5190 
5191   if (!rp->processing_is_mt()) {
5192     // Serial reference processing...
5193     rp->process_discovered_references(&is_alive,
5194                                       &keep_alive,
5195                                       &drain_queue,
5196                                       NULL);
5197   } else {
5198     // Parallel reference processing
5199     int active_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
5200     assert(rp->num_q() == active_workers, "sanity");
5201     assert(active_workers <= rp->max_num_q(), "sanity");
5202 
5203     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5204     rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5205   }
5206 
5207   // We have completed copying any necessary live referent objects
5208   // (that were not copied during the actual pause) so we can
5209   // retire any active alloc buffers
5210   pss.retire_alloc_buffers();
5211   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5212 
5213   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5214   g1_policy()->record_ref_proc_time(ref_proc_time * 1000.0);
5215 }
5216 
5217 // Weak Reference processing during an evacuation pause (part 2).
5218 void G1CollectedHeap::enqueue_discovered_references() {
5219   double ref_enq_start = os::elapsedTime();
5220 
5221   ReferenceProcessor* rp = _ref_processor_stw;
5222   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5223 
5224   // Now enqueue any remaining on the discovered lists on to
5225   // the pending list.
5226   if (!rp->processing_is_mt()) {
5227     // Serial reference processing...
5228     rp->enqueue_discovered_references();
5229   } else {
5230     // Parallel reference enqueuing
5231 
5232     int active_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
5233     assert(rp->num_q() == active_workers, "sanity");
5234     assert(active_workers <= rp->max_num_q(), "sanity");
5235 
5236     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5237     rp->enqueue_discovered_references(&par_task_executor);
5238   }
5239 
5240   rp->verify_no_references_recorded();
5241   assert(!rp->discovery_enabled(), "should have been disabled");
5242 
5243   // FIXME
5244   // CM's reference processing also cleans up the string and symbol tables.
5245   // Should we do that here also? We could, but it is a serial operation
5246   // and could signicantly increase the pause time.
5247 
5248   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5249   g1_policy()->record_ref_enq_time(ref_enq_time * 1000.0);
5250 }
5251 
5252 void G1CollectedHeap::evacuate_collection_set() {
5253   set_evacuation_failed(false);
5254 
5255   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5256   concurrent_g1_refine()->set_use_cache(false);
5257   concurrent_g1_refine()->clear_hot_cache_claimed_index();
5258 
5259   int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
5260   set_par_threads(n_workers);
5261   G1ParTask g1_par_task(this, n_workers, _task_queues);
5262 
5263   init_for_evac_failure(NULL);
5264 
5265   rem_set()->prepare_for_younger_refs_iterate(true);
5266 
5267   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5268   double start_par = os::elapsedTime();
5269 
5270   if (G1CollectedHeap::use_parallel_gc_threads()) {
5271     // The individual threads will set their evac-failure closures.
5272     StrongRootsScope srs(this);
5273     if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5274     workers()->run_task(&g1_par_task);
5275   } else {
5276     StrongRootsScope srs(this);
5277     g1_par_task.work(0);
5278   }
5279 
5280   double par_time = (os::elapsedTime() - start_par) * 1000.0;
5281   g1_policy()->record_par_time(par_time);
5282   set_par_threads(0);
5283 
5284   // Process any discovered reference objects - we have
5285   // to do this _before_ we retire the GC alloc regions
5286   // as we may have to copy some 'reachable' referent
5287   // objects (and their reachable sub-graphs) that were
5288   // not copied during the pause.
5289   process_discovered_references();
5290 
5291   // Weak root processing.
5292   // Note: when JSR 292 is enabled and code blobs can contain
5293   // non-perm oops then we will need to process the code blobs
5294   // here too.
5295   {
5296     G1STWIsAliveClosure is_alive(this);
5297     G1KeepAliveClosure keep_alive(this);
5298     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5299   }
5300 
5301   release_gc_alloc_regions();
5302   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5303 
5304   concurrent_g1_refine()->clear_hot_cache();
5305   concurrent_g1_refine()->set_use_cache(true);
5306 
5307   finalize_for_evac_failure();
5308 
5309   // Must do this before removing self-forwarding pointers, which clears
5310   // the per-region evac-failure flags.
5311   concurrent_mark()->complete_marking_in_collection_set();
5312 
5313   if (evacuation_failed()) {
5314     remove_self_forwarding_pointers();
5315     if (PrintGCDetails) {
5316       gclog_or_tty->print(" (to-space overflow)");
5317     } else if (PrintGC) {
5318       gclog_or_tty->print("--");
5319     }
5320   }
5321 
5322   // Enqueue any remaining references remaining on the STW
5323   // reference processor's discovered lists. We need to do
5324   // this after the card table is cleaned (and verified) as
5325   // the act of enqueuing entries on to the pending list
5326   // will log these updates (and dirty their associated
5327   // cards). We need these updates logged to update any
5328   // RSets.
5329   enqueue_discovered_references();
5330 
5331   if (G1DeferredRSUpdate) {
5332     RedirtyLoggedCardTableEntryFastClosure redirty;
5333     dirty_card_queue_set().set_closure(&redirty);
5334     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5335 
5336     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5337     dcq.merge_bufferlists(&dirty_card_queue_set());
5338     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5339   }
5340   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5341 }
5342 
5343 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5344                                      size_t* pre_used,
5345                                      FreeRegionList* free_list,
5346                                      HumongousRegionSet* humongous_proxy_set,
5347                                      HRRSCleanupTask* hrrs_cleanup_task,
5348                                      bool par) {
5349   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5350     if (hr->isHumongous()) {
5351       assert(hr->startsHumongous(), "we should only see starts humongous");
5352       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5353     } else {
5354       free_region(hr, pre_used, free_list, par);
5355     }
5356   } else {
5357     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5358   }
5359 }
5360 
5361 void G1CollectedHeap::free_region(HeapRegion* hr,
5362                                   size_t* pre_used,
5363                                   FreeRegionList* free_list,
5364                                   bool par) {
5365   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5366   assert(!hr->is_empty(), "the region should not be empty");
5367   assert(free_list != NULL, "pre-condition");
5368 
5369   *pre_used += hr->used();
5370   hr->hr_clear(par, true /* clear_space */);
5371   free_list->add_as_head(hr);
5372 }
5373 
5374 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5375                                      size_t* pre_used,
5376                                      FreeRegionList* free_list,
5377                                      HumongousRegionSet* humongous_proxy_set,
5378                                      bool par) {
5379   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5380   assert(free_list != NULL, "pre-condition");
5381   assert(humongous_proxy_set != NULL, "pre-condition");
5382 
5383   size_t hr_used = hr->used();
5384   size_t hr_capacity = hr->capacity();
5385   size_t hr_pre_used = 0;
5386   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5387   hr->set_notHumongous();
5388   free_region(hr, &hr_pre_used, free_list, par);
5389 
5390   size_t i = hr->hrs_index() + 1;
5391   size_t num = 1;
5392   while (i < n_regions()) {
5393     HeapRegion* curr_hr = region_at(i);
5394     if (!curr_hr->continuesHumongous()) {
5395       break;
5396     }
5397     curr_hr->set_notHumongous();
5398     free_region(curr_hr, &hr_pre_used, free_list, par);
5399     num += 1;
5400     i += 1;
5401   }
5402   assert(hr_pre_used == hr_used,
5403          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5404                  "should be the same", hr_pre_used, hr_used));
5405   *pre_used += hr_pre_used;
5406 }
5407 
5408 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5409                                        FreeRegionList* free_list,
5410                                        HumongousRegionSet* humongous_proxy_set,
5411                                        bool par) {
5412   if (pre_used > 0) {
5413     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5414     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5415     assert(_summary_bytes_used >= pre_used,
5416            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5417                    "should be >= pre_used: "SIZE_FORMAT,
5418                    _summary_bytes_used, pre_used));
5419     _summary_bytes_used -= pre_used;
5420   }
5421   if (free_list != NULL && !free_list->is_empty()) {
5422     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5423     _free_list.add_as_head(free_list);
5424   }
5425   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5426     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5427     _humongous_set.update_from_proxy(humongous_proxy_set);
5428   }
5429 }
5430 
5431 class G1ParCleanupCTTask : public AbstractGangTask {
5432   CardTableModRefBS* _ct_bs;
5433   G1CollectedHeap* _g1h;
5434   HeapRegion* volatile _su_head;
5435 public:
5436   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5437                      G1CollectedHeap* g1h) :
5438     AbstractGangTask("G1 Par Cleanup CT Task"),
5439     _ct_bs(ct_bs), _g1h(g1h) { }
5440 
5441   void work(int i) {
5442     HeapRegion* r;
5443     while (r = _g1h->pop_dirty_cards_region()) {
5444       clear_cards(r);
5445     }
5446   }
5447 
5448   void clear_cards(HeapRegion* r) {
5449     // Cards of the survivors should have already been dirtied.
5450     if (!r->is_survivor()) {
5451       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5452     }
5453   }
5454 };
5455 
5456 #ifndef PRODUCT
5457 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5458   G1CollectedHeap* _g1h;
5459   CardTableModRefBS* _ct_bs;
5460 public:
5461   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5462     : _g1h(g1h), _ct_bs(ct_bs) { }
5463   virtual bool doHeapRegion(HeapRegion* r) {
5464     if (r->is_survivor()) {
5465       _g1h->verify_dirty_region(r);
5466     } else {
5467       _g1h->verify_not_dirty_region(r);
5468     }
5469     return false;
5470   }
5471 };
5472 
5473 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5474   // All of the region should be clean.
5475   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5476   MemRegion mr(hr->bottom(), hr->end());
5477   ct_bs->verify_not_dirty_region(mr);
5478 }
5479 
5480 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5481   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5482   // dirty allocated blocks as they allocate them. The thread that
5483   // retires each region and replaces it with a new one will do a
5484   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5485   // not dirty that area (one less thing to have to do while holding
5486   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5487   // is dirty.
5488   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5489   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5490   ct_bs->verify_dirty_region(mr);
5491 }
5492 
5493 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5494   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5495   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5496     verify_dirty_region(hr);
5497   }
5498 }
5499 
5500 void G1CollectedHeap::verify_dirty_young_regions() {
5501   verify_dirty_young_list(_young_list->first_region());
5502   verify_dirty_young_list(_young_list->first_survivor_region());
5503 }
5504 #endif
5505 
5506 void G1CollectedHeap::cleanUpCardTable() {
5507   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5508   double start = os::elapsedTime();
5509 
5510   // Iterate over the dirty cards region list.
5511   G1ParCleanupCTTask cleanup_task(ct_bs, this);
5512 
5513   if (ParallelGCThreads > 0) {
5514     set_par_threads(workers()->total_workers());
5515     workers()->run_task(&cleanup_task);
5516     set_par_threads(0);
5517   } else {
5518     while (_dirty_cards_region_list) {
5519       HeapRegion* r = _dirty_cards_region_list;
5520       cleanup_task.clear_cards(r);
5521       _dirty_cards_region_list = r->get_next_dirty_cards_region();
5522       if (_dirty_cards_region_list == r) {
5523         // The last region.
5524         _dirty_cards_region_list = NULL;
5525       }
5526       r->set_next_dirty_cards_region(NULL);
5527     }
5528   }
5529 
5530   double elapsed = os::elapsedTime() - start;
5531   g1_policy()->record_clear_ct_time(elapsed * 1000.0);
5532 #ifndef PRODUCT
5533   if (G1VerifyCTCleanup || VerifyAfterGC) {
5534     G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5535     heap_region_iterate(&cleanup_verifier);
5536   }
5537 #endif
5538 }
5539 
5540 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5541   size_t pre_used = 0;
5542   FreeRegionList local_free_list("Local List for CSet Freeing");
5543 
5544   double young_time_ms     = 0.0;
5545   double non_young_time_ms = 0.0;
5546 
5547   // Since the collection set is a superset of the the young list,
5548   // all we need to do to clear the young list is clear its
5549   // head and length, and unlink any young regions in the code below
5550   _young_list->clear();
5551 
5552   G1CollectorPolicy* policy = g1_policy();
5553 
5554   double start_sec = os::elapsedTime();
5555   bool non_young = true;
5556 
5557   HeapRegion* cur = cs_head;
5558   int age_bound = -1;
5559   size_t rs_lengths = 0;
5560 
5561   while (cur != NULL) {
5562     assert(!is_on_master_free_list(cur), "sanity");
5563 
5564     if (non_young) {
5565       if (cur->is_young()) {
5566         double end_sec = os::elapsedTime();
5567         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5568         non_young_time_ms += elapsed_ms;
5569 
5570         start_sec = os::elapsedTime();
5571         non_young = false;
5572       }
5573     } else {
5574       double end_sec = os::elapsedTime();
5575       double elapsed_ms = (end_sec - start_sec) * 1000.0;
5576       young_time_ms += elapsed_ms;
5577 
5578       start_sec = os::elapsedTime();
5579       non_young = true;
5580     }
5581 
5582     rs_lengths += cur->rem_set()->occupied();
5583 
5584     HeapRegion* next = cur->next_in_collection_set();
5585     assert(cur->in_collection_set(), "bad CS");
5586     cur->set_next_in_collection_set(NULL);
5587     cur->set_in_collection_set(false);
5588 
5589     if (cur->is_young()) {
5590       int index = cur->young_index_in_cset();
5591       guarantee( index != -1, "invariant" );
5592       guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
5593       size_t words_survived = _surviving_young_words[index];
5594       cur->record_surv_words_in_group(words_survived);
5595 
5596       // At this point the we have 'popped' cur from the collection set
5597       // (linked via next_in_collection_set()) but it is still in the
5598       // young list (linked via next_young_region()). Clear the
5599       // _next_young_region field.
5600       cur->set_next_young_region(NULL);
5601     } else {
5602       int index = cur->young_index_in_cset();
5603       guarantee( index == -1, "invariant" );
5604     }
5605 
5606     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5607             (!cur->is_young() && cur->young_index_in_cset() == -1),
5608             "invariant" );
5609 
5610     if (!cur->evacuation_failed()) {
5611       // And the region is empty.
5612       assert(!cur->is_empty(), "Should not have empty regions in a CS.");
5613       free_region(cur, &pre_used, &local_free_list, false /* par */);
5614     } else {
5615       cur->uninstall_surv_rate_group();
5616       if (cur->is_young())
5617         cur->set_young_index_in_cset(-1);
5618       cur->set_not_young();
5619       cur->set_evacuation_failed(false);
5620     }
5621     cur = next;
5622   }
5623 
5624   policy->record_max_rs_lengths(rs_lengths);
5625   policy->cset_regions_freed();
5626 
5627   double end_sec = os::elapsedTime();
5628   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5629   if (non_young)
5630     non_young_time_ms += elapsed_ms;
5631   else
5632     young_time_ms += elapsed_ms;
5633 
5634   update_sets_after_freeing_regions(pre_used, &local_free_list,
5635                                     NULL /* humongous_proxy_set */,
5636                                     false /* par */);
5637   policy->record_young_free_cset_time_ms(young_time_ms);
5638   policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5639 }
5640 
5641 // This routine is similar to the above but does not record
5642 // any policy statistics or update free lists; we are abandoning
5643 // the current incremental collection set in preparation of a
5644 // full collection. After the full GC we will start to build up
5645 // the incremental collection set again.
5646 // This is only called when we're doing a full collection
5647 // and is immediately followed by the tearing down of the young list.
5648 
5649 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5650   HeapRegion* cur = cs_head;
5651 
5652   while (cur != NULL) {
5653     HeapRegion* next = cur->next_in_collection_set();
5654     assert(cur->in_collection_set(), "bad CS");
5655     cur->set_next_in_collection_set(NULL);
5656     cur->set_in_collection_set(false);
5657     cur->set_young_index_in_cset(-1);
5658     cur = next;
5659   }
5660 }
5661 
5662 void G1CollectedHeap::set_free_regions_coming() {
5663   if (G1ConcRegionFreeingVerbose) {
5664     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5665                            "setting free regions coming");
5666   }
5667 
5668   assert(!free_regions_coming(), "pre-condition");
5669   _free_regions_coming = true;
5670 }
5671 
5672 void G1CollectedHeap::reset_free_regions_coming() {
5673   {
5674     assert(free_regions_coming(), "pre-condition");
5675     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5676     _free_regions_coming = false;
5677     SecondaryFreeList_lock->notify_all();
5678   }
5679 
5680   if (G1ConcRegionFreeingVerbose) {
5681     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5682                            "reset free regions coming");
5683   }
5684 }
5685 
5686 void G1CollectedHeap::wait_while_free_regions_coming() {
5687   // Most of the time we won't have to wait, so let's do a quick test
5688   // first before we take the lock.
5689   if (!free_regions_coming()) {
5690     return;
5691   }
5692 
5693   if (G1ConcRegionFreeingVerbose) {
5694     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5695                            "waiting for free regions");
5696   }
5697 
5698   {
5699     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5700     while (free_regions_coming()) {
5701       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5702     }
5703   }
5704 
5705   if (G1ConcRegionFreeingVerbose) {
5706     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5707                            "done waiting for free regions");
5708   }
5709 }
5710 
5711 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5712   assert(heap_lock_held_for_gc(),
5713               "the heap lock should already be held by or for this thread");
5714   _young_list->push_region(hr);
5715   g1_policy()->set_region_short_lived(hr);
5716 }
5717 
5718 class NoYoungRegionsClosure: public HeapRegionClosure {
5719 private:
5720   bool _success;
5721 public:
5722   NoYoungRegionsClosure() : _success(true) { }
5723   bool doHeapRegion(HeapRegion* r) {
5724     if (r->is_young()) {
5725       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5726                              r->bottom(), r->end());
5727       _success = false;
5728     }
5729     return false;
5730   }
5731   bool success() { return _success; }
5732 };
5733 
5734 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5735   bool ret = _young_list->check_list_empty(check_sample);
5736 
5737   if (check_heap) {
5738     NoYoungRegionsClosure closure;
5739     heap_region_iterate(&closure);
5740     ret = ret && closure.success();
5741   }
5742 
5743   return ret;
5744 }
5745 
5746 void G1CollectedHeap::empty_young_list() {
5747   assert(heap_lock_held_for_gc(),
5748               "the heap lock should already be held by or for this thread");
5749 
5750   _young_list->empty_list();
5751 }
5752 
5753 // Done at the start of full GC.
5754 void G1CollectedHeap::tear_down_region_lists() {
5755   _free_list.remove_all();
5756 }
5757 
5758 class RegionResetter: public HeapRegionClosure {
5759   G1CollectedHeap* _g1h;
5760   FreeRegionList _local_free_list;
5761 
5762 public:
5763   RegionResetter() : _g1h(G1CollectedHeap::heap()),
5764                      _local_free_list("Local Free List for RegionResetter") { }
5765 
5766   bool doHeapRegion(HeapRegion* r) {
5767     if (r->continuesHumongous()) return false;
5768     if (r->top() > r->bottom()) {
5769       if (r->top() < r->end()) {
5770         Copy::fill_to_words(r->top(),
5771                           pointer_delta(r->end(), r->top()));
5772       }
5773     } else {
5774       assert(r->is_empty(), "tautology");
5775       _local_free_list.add_as_tail(r);
5776     }
5777     return false;
5778   }
5779 
5780   void update_free_lists() {
5781     _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL,
5782                                             false /* par */);
5783   }
5784 };
5785 
5786 // Done at the end of full GC.
5787 void G1CollectedHeap::rebuild_region_lists() {
5788   // This needs to go at the end of the full GC.
5789   RegionResetter rs;
5790   heap_region_iterate(&rs);
5791   rs.update_free_lists();
5792 }
5793 
5794 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5795   _refine_cte_cl->set_concurrent(concurrent);
5796 }
5797 
5798 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5799   HeapRegion* hr = heap_region_containing(p);
5800   if (hr == NULL) {
5801     return is_in_permanent(p);
5802   } else {
5803     return hr->is_in(p);
5804   }
5805 }
5806 
5807 // Methods for the mutator alloc region
5808 
5809 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5810                                                       bool force) {
5811   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5812   assert(!force || g1_policy()->can_expand_young_list(),
5813          "if force is true we should be able to expand the young list");
5814   bool young_list_full = g1_policy()->is_young_list_full();
5815   if (force || !young_list_full) {
5816     HeapRegion* new_alloc_region = new_region(word_size,
5817                                               false /* do_expand */);
5818     if (new_alloc_region != NULL) {
5819       g1_policy()->update_region_num(true /* next_is_young */);
5820       set_region_short_lived_locked(new_alloc_region);
5821       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
5822       return new_alloc_region;
5823     }
5824   }
5825   return NULL;
5826 }
5827 
5828 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5829                                                   size_t allocated_bytes) {
5830   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5831   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
5832 
5833   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5834   _summary_bytes_used += allocated_bytes;
5835   _hr_printer.retire(alloc_region);
5836   // We update the eden sizes here, when the region is retired,
5837   // instead of when it's allocated, since this is the point that its
5838   // used space has been recored in _summary_bytes_used.
5839   g1mm()->update_eden_size();
5840 }
5841 
5842 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
5843                                                     bool force) {
5844   return _g1h->new_mutator_alloc_region(word_size, force);
5845 }
5846 
5847 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
5848                                        size_t allocated_bytes) {
5849   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
5850 }
5851 
5852 // Methods for the GC alloc regions
5853 
5854 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5855                                                  size_t count,
5856                                                  GCAllocPurpose ap) {
5857   assert(FreeList_lock->owned_by_self(), "pre-condition");
5858 
5859   if (count < g1_policy()->max_regions(ap)) {
5860     HeapRegion* new_alloc_region = new_region(word_size,
5861                                               true /* do_expand */);
5862     if (new_alloc_region != NULL) {
5863       // We really only need to do this for old regions given that we
5864       // should never scan survivors. But it doesn't hurt to do it
5865       // for survivors too.
5866       new_alloc_region->set_saved_mark();
5867       if (ap == GCAllocForSurvived) {
5868         new_alloc_region->set_survivor();
5869         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
5870       } else {
5871         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
5872       }
5873       return new_alloc_region;
5874     } else {
5875       g1_policy()->note_alloc_region_limit_reached(ap);
5876     }
5877   }
5878   return NULL;
5879 }
5880 
5881 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5882                                              size_t allocated_bytes,
5883                                              GCAllocPurpose ap) {
5884   alloc_region->note_end_of_copying();
5885   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5886   if (ap == GCAllocForSurvived) {
5887     young_list()->add_survivor_region(alloc_region);
5888   }
5889   _hr_printer.retire(alloc_region);
5890 }
5891 
5892 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
5893                                                        bool force) {
5894   assert(!force, "not supported for GC alloc regions");
5895   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
5896 }
5897 
5898 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
5899                                           size_t allocated_bytes) {
5900   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
5901                                GCAllocForSurvived);
5902 }
5903 
5904 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
5905                                                   bool force) {
5906   assert(!force, "not supported for GC alloc regions");
5907   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
5908 }
5909 
5910 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
5911                                      size_t allocated_bytes) {
5912   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
5913                                GCAllocForTenured);
5914 }
5915 // Heap region set verification
5916 
5917 class VerifyRegionListsClosure : public HeapRegionClosure {
5918 private:
5919   HumongousRegionSet* _humongous_set;
5920   FreeRegionList*     _free_list;
5921   size_t              _region_count;
5922 
5923 public:
5924   VerifyRegionListsClosure(HumongousRegionSet* humongous_set,
5925                            FreeRegionList* free_list) :
5926     _humongous_set(humongous_set), _free_list(free_list),
5927     _region_count(0) { }
5928 
5929   size_t region_count()      { return _region_count;      }
5930 
5931   bool doHeapRegion(HeapRegion* hr) {
5932     _region_count += 1;
5933 
5934     if (hr->continuesHumongous()) {
5935       return false;
5936     }
5937 
5938     if (hr->is_young()) {
5939       // TODO
5940     } else if (hr->startsHumongous()) {
5941       _humongous_set->verify_next_region(hr);
5942     } else if (hr->is_empty()) {
5943       _free_list->verify_next_region(hr);
5944     }
5945     return false;
5946   }
5947 };
5948 
5949 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index,
5950                                              HeapWord* bottom) {
5951   HeapWord* end = bottom + HeapRegion::GrainWords;
5952   MemRegion mr(bottom, end);
5953   assert(_g1_reserved.contains(mr), "invariant");
5954   // This might return NULL if the allocation fails
5955   return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
5956 }
5957 
5958 void G1CollectedHeap::verify_region_sets() {
5959   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5960 
5961   // First, check the explicit lists.
5962   _free_list.verify();
5963   {
5964     // Given that a concurrent operation might be adding regions to
5965     // the secondary free list we have to take the lock before
5966     // verifying it.
5967     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5968     _secondary_free_list.verify();
5969   }
5970   _humongous_set.verify();
5971 
5972   // If a concurrent region freeing operation is in progress it will
5973   // be difficult to correctly attributed any free regions we come
5974   // across to the correct free list given that they might belong to
5975   // one of several (free_list, secondary_free_list, any local lists,
5976   // etc.). So, if that's the case we will skip the rest of the
5977   // verification operation. Alternatively, waiting for the concurrent
5978   // operation to complete will have a non-trivial effect on the GC's
5979   // operation (no concurrent operation will last longer than the
5980   // interval between two calls to verification) and it might hide
5981   // any issues that we would like to catch during testing.
5982   if (free_regions_coming()) {
5983     return;
5984   }
5985 
5986   // Make sure we append the secondary_free_list on the free_list so
5987   // that all free regions we will come across can be safely
5988   // attributed to the free_list.
5989   append_secondary_free_list_if_not_empty_with_lock();
5990 
5991   // Finally, make sure that the region accounting in the lists is
5992   // consistent with what we see in the heap.
5993   _humongous_set.verify_start();
5994   _free_list.verify_start();
5995 
5996   VerifyRegionListsClosure cl(&_humongous_set, &_free_list);
5997   heap_region_iterate(&cl);
5998 
5999   _humongous_set.verify_end();
6000   _free_list.verify_end();
6001 }