1 /*
   2  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #if !defined(__clang_major__) && defined(__GNUC__)
  26 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess.
  27 #endif
  28 
  29 #include "precompiled.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/icBuffer.hpp"
  32 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  33 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  34 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  35 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  36 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  37 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  38 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  39 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  40 #include "gc_implementation/g1/g1EvacFailure.hpp"
  41 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  42 #include "gc_implementation/g1/g1Log.hpp"
  43 #include "gc_implementation/g1/g1MarkSweep.hpp"
  44 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  45 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
  46 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  47 #include "gc_implementation/g1/g1StringDedup.hpp"
  48 #include "gc_implementation/g1/g1YCTypes.hpp"
  49 #include "gc_implementation/g1/heapRegion.inline.hpp"
  50 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  51 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  52 #include "gc_implementation/g1/vm_operations_g1.hpp"
  53 #include "gc_implementation/shared/gcHeapSummary.hpp"
  54 #include "gc_implementation/shared/gcTimer.hpp"
  55 #include "gc_implementation/shared/gcTrace.hpp"
  56 #include "gc_implementation/shared/gcTraceTime.hpp"
  57 #include "gc_implementation/shared/isGCActiveMark.hpp"
  58 #include "memory/gcLocker.inline.hpp"
  59 #include "memory/generationSpec.hpp"
  60 #include "memory/iterator.hpp"
  61 #include "memory/referenceProcessor.hpp"
  62 #include "oops/oop.inline.hpp"
  63 #include "oops/oop.pcgc.inline.hpp"
  64 #include "runtime/orderAccess.inline.hpp"
  65 #include "runtime/vmThread.hpp"
  66 
  67 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  68 
  69 // turn it on so that the contents of the young list (scan-only /
  70 // to-be-collected) are printed at "strategic" points before / during
  71 // / after the collection --- this is useful for debugging
  72 #define YOUNG_LIST_VERBOSE 0
  73 // CURRENT STATUS
  74 // This file is under construction.  Search for "FIXME".
  75 
  76 // INVARIANTS/NOTES
  77 //
  78 // All allocation activity covered by the G1CollectedHeap interface is
  79 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  80 // and allocate_new_tlab, which are the "entry" points to the
  81 // allocation code from the rest of the JVM.  (Note that this does not
  82 // apply to TLAB allocation, which is not part of this interface: it
  83 // is done by clients of this interface.)
  84 
  85 // Notes on implementation of parallelism in different tasks.
  86 //
  87 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  88 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  89 // It does use run_task() which sets _n_workers in the task.
  90 // G1ParTask executes g1_process_strong_roots() ->
  91 // SharedHeap::process_strong_roots() which calls eventually to
  92 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  93 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  94 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  95 //
  96 
  97 // Local to this file.
  98 
  99 class RefineCardTableEntryClosure: public CardTableEntryClosure {
 100   bool _concurrent;
 101 public:
 102   RefineCardTableEntryClosure() : _concurrent(true) { }
 103 
 104   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 105     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 106     // This path is executed by the concurrent refine or mutator threads,
 107     // concurrently, and so we do not care if card_ptr contains references
 108     // that point into the collection set.
 109     assert(!oops_into_cset, "should be");
 110 
 111     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 112       // Caller will actually yield.
 113       return false;
 114     }
 115     // Otherwise, we finished successfully; return true.
 116     return true;
 117   }
 118 
 119   void set_concurrent(bool b) { _concurrent = b; }
 120 };
 121 
 122 
 123 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 124   size_t _num_processed;
 125   CardTableModRefBS* _ctbs;
 126   int _histo[256];
 127 
 128  public:
 129   ClearLoggedCardTableEntryClosure() :
 130     _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
 131   {
 132     for (int i = 0; i < 256; i++) _histo[i] = 0;
 133   }
 134 
 135   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 136     unsigned char* ujb = (unsigned char*)card_ptr;
 137     int ind = (int)(*ujb);
 138     _histo[ind]++;
 139 
 140     *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
 141     _num_processed++;
 142 
 143     return true;
 144   }
 145 
 146   size_t num_processed() { return _num_processed; }
 147 
 148   void print_histo() {
 149     gclog_or_tty->print_cr("Card table value histogram:");
 150     for (int i = 0; i < 256; i++) {
 151       if (_histo[i] != 0) {
 152         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 153       }
 154     }
 155   }
 156 };
 157 
 158 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 159  private:
 160   size_t _num_processed;
 161 
 162  public:
 163   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 164 
 165   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 166     *card_ptr = CardTableModRefBS::dirty_card_val();
 167     _num_processed++;
 168     return true;
 169   }
 170 
 171   size_t num_processed() const { return _num_processed; }
 172 };
 173 
 174 YoungList::YoungList(G1CollectedHeap* g1h) :
 175     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 176     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 177   guarantee(check_list_empty(false), "just making sure...");
 178 }
 179 
 180 void YoungList::push_region(HeapRegion *hr) {
 181   assert(!hr->is_young(), "should not already be young");
 182   assert(hr->get_next_young_region() == NULL, "cause it should!");
 183 
 184   hr->set_next_young_region(_head);
 185   _head = hr;
 186 
 187   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 188   ++_length;
 189 }
 190 
 191 void YoungList::add_survivor_region(HeapRegion* hr) {
 192   assert(hr->is_survivor(), "should be flagged as survivor region");
 193   assert(hr->get_next_young_region() == NULL, "cause it should!");
 194 
 195   hr->set_next_young_region(_survivor_head);
 196   if (_survivor_head == NULL) {
 197     _survivor_tail = hr;
 198   }
 199   _survivor_head = hr;
 200   ++_survivor_length;
 201 }
 202 
 203 void YoungList::empty_list(HeapRegion* list) {
 204   while (list != NULL) {
 205     HeapRegion* next = list->get_next_young_region();
 206     list->set_next_young_region(NULL);
 207     list->uninstall_surv_rate_group();
 208     list->set_not_young();
 209     list = next;
 210   }
 211 }
 212 
 213 void YoungList::empty_list() {
 214   assert(check_list_well_formed(), "young list should be well formed");
 215 
 216   empty_list(_head);
 217   _head = NULL;
 218   _length = 0;
 219 
 220   empty_list(_survivor_head);
 221   _survivor_head = NULL;
 222   _survivor_tail = NULL;
 223   _survivor_length = 0;
 224 
 225   _last_sampled_rs_lengths = 0;
 226 
 227   assert(check_list_empty(false), "just making sure...");
 228 }
 229 
 230 bool YoungList::check_list_well_formed() {
 231   bool ret = true;
 232 
 233   uint length = 0;
 234   HeapRegion* curr = _head;
 235   HeapRegion* last = NULL;
 236   while (curr != NULL) {
 237     if (!curr->is_young()) {
 238       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 239                              "incorrectly tagged (y: %d, surv: %d)",
 240                              curr->bottom(), curr->end(),
 241                              curr->is_young(), curr->is_survivor());
 242       ret = false;
 243     }
 244     ++length;
 245     last = curr;
 246     curr = curr->get_next_young_region();
 247   }
 248   ret = ret && (length == _length);
 249 
 250   if (!ret) {
 251     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 252     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 253                            length, _length);
 254   }
 255 
 256   return ret;
 257 }
 258 
 259 bool YoungList::check_list_empty(bool check_sample) {
 260   bool ret = true;
 261 
 262   if (_length != 0) {
 263     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 264                   _length);
 265     ret = false;
 266   }
 267   if (check_sample && _last_sampled_rs_lengths != 0) {
 268     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 269     ret = false;
 270   }
 271   if (_head != NULL) {
 272     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 273     ret = false;
 274   }
 275   if (!ret) {
 276     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 277   }
 278 
 279   return ret;
 280 }
 281 
 282 void
 283 YoungList::rs_length_sampling_init() {
 284   _sampled_rs_lengths = 0;
 285   _curr               = _head;
 286 }
 287 
 288 bool
 289 YoungList::rs_length_sampling_more() {
 290   return _curr != NULL;
 291 }
 292 
 293 void
 294 YoungList::rs_length_sampling_next() {
 295   assert( _curr != NULL, "invariant" );
 296   size_t rs_length = _curr->rem_set()->occupied();
 297 
 298   _sampled_rs_lengths += rs_length;
 299 
 300   // The current region may not yet have been added to the
 301   // incremental collection set (it gets added when it is
 302   // retired as the current allocation region).
 303   if (_curr->in_collection_set()) {
 304     // Update the collection set policy information for this region
 305     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 306   }
 307 
 308   _curr = _curr->get_next_young_region();
 309   if (_curr == NULL) {
 310     _last_sampled_rs_lengths = _sampled_rs_lengths;
 311     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 312   }
 313 }
 314 
 315 void
 316 YoungList::reset_auxilary_lists() {
 317   guarantee( is_empty(), "young list should be empty" );
 318   assert(check_list_well_formed(), "young list should be well formed");
 319 
 320   // Add survivor regions to SurvRateGroup.
 321   _g1h->g1_policy()->note_start_adding_survivor_regions();
 322   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 323 
 324   int young_index_in_cset = 0;
 325   for (HeapRegion* curr = _survivor_head;
 326        curr != NULL;
 327        curr = curr->get_next_young_region()) {
 328     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 329 
 330     // The region is a non-empty survivor so let's add it to
 331     // the incremental collection set for the next evacuation
 332     // pause.
 333     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 334     young_index_in_cset += 1;
 335   }
 336   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 337   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 338 
 339   _head   = _survivor_head;
 340   _length = _survivor_length;
 341   if (_survivor_head != NULL) {
 342     assert(_survivor_tail != NULL, "cause it shouldn't be");
 343     assert(_survivor_length > 0, "invariant");
 344     _survivor_tail->set_next_young_region(NULL);
 345   }
 346 
 347   // Don't clear the survivor list handles until the start of
 348   // the next evacuation pause - we need it in order to re-tag
 349   // the survivor regions from this evacuation pause as 'young'
 350   // at the start of the next.
 351 
 352   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 353 
 354   assert(check_list_well_formed(), "young list should be well formed");
 355 }
 356 
 357 void YoungList::print() {
 358   HeapRegion* lists[] = {_head,   _survivor_head};
 359   const char* names[] = {"YOUNG", "SURVIVOR"};
 360 
 361   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 362     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 363     HeapRegion *curr = lists[list];
 364     if (curr == NULL)
 365       gclog_or_tty->print_cr("  empty");
 366     while (curr != NULL) {
 367       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 368                              HR_FORMAT_PARAMS(curr),
 369                              curr->prev_top_at_mark_start(),
 370                              curr->next_top_at_mark_start(),
 371                              curr->age_in_surv_rate_group_cond());
 372       curr = curr->get_next_young_region();
 373     }
 374   }
 375 
 376   gclog_or_tty->cr();
 377 }
 378 
 379 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 380 {
 381   // Claim the right to put the region on the dirty cards region list
 382   // by installing a self pointer.
 383   HeapRegion* next = hr->get_next_dirty_cards_region();
 384   if (next == NULL) {
 385     HeapRegion* res = (HeapRegion*)
 386       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 387                           NULL);
 388     if (res == NULL) {
 389       HeapRegion* head;
 390       do {
 391         // Put the region to the dirty cards region list.
 392         head = _dirty_cards_region_list;
 393         next = (HeapRegion*)
 394           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 395         if (next == head) {
 396           assert(hr->get_next_dirty_cards_region() == hr,
 397                  "hr->get_next_dirty_cards_region() != hr");
 398           if (next == NULL) {
 399             // The last region in the list points to itself.
 400             hr->set_next_dirty_cards_region(hr);
 401           } else {
 402             hr->set_next_dirty_cards_region(next);
 403           }
 404         }
 405       } while (next != head);
 406     }
 407   }
 408 }
 409 
 410 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 411 {
 412   HeapRegion* head;
 413   HeapRegion* hr;
 414   do {
 415     head = _dirty_cards_region_list;
 416     if (head == NULL) {
 417       return NULL;
 418     }
 419     HeapRegion* new_head = head->get_next_dirty_cards_region();
 420     if (head == new_head) {
 421       // The last region.
 422       new_head = NULL;
 423     }
 424     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 425                                           head);
 426   } while (hr != head);
 427   assert(hr != NULL, "invariant");
 428   hr->set_next_dirty_cards_region(NULL);
 429   return hr;
 430 }
 431 
 432 #ifdef ASSERT
 433 // A region is added to the collection set as it is retired
 434 // so an address p can point to a region which will be in the
 435 // collection set but has not yet been retired.  This method
 436 // therefore is only accurate during a GC pause after all
 437 // regions have been retired.  It is used for debugging
 438 // to check if an nmethod has references to objects that can
 439 // be move during a partial collection.  Though it can be
 440 // inaccurate, it is sufficient for G1 because the conservative
 441 // implementation of is_scavengable() for G1 will indicate that
 442 // all nmethods must be scanned during a partial collection.
 443 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 444   HeapRegion* hr = heap_region_containing(p);
 445   return hr != NULL && hr->in_collection_set();
 446 }
 447 #endif
 448 
 449 // Returns true if the reference points to an object that
 450 // can move in an incremental collection.
 451 bool G1CollectedHeap::is_scavengable(const void* p) {
 452   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 453   G1CollectorPolicy* g1p = g1h->g1_policy();
 454   HeapRegion* hr = heap_region_containing(p);
 455   if (hr == NULL) {
 456      // null
 457      assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
 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 = g1_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.apply_closure_to_all_completed_buffers(&clear);
 476   dcqs.iterate_closure_all_threads(&clear, false);
 477   clear.print_histo();
 478 
 479   // Now ensure that there's no dirty cards.
 480   CountNonCleanMemRegionClosure count2(this);
 481   ct_bs->mod_card_iterate(&count2);
 482   if (count2.n() != 0) {
 483     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 484                            count2.n(), orig_count);
 485   }
 486   guarantee(count2.n() == 0, "Card table should be clean.");
 487 
 488   RedirtyLoggedCardTableEntryClosure redirty;
 489   dcqs.apply_closure_to_all_completed_buffers(&redirty);
 490   dcqs.iterate_closure_all_threads(&redirty, false);
 491   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 492                          clear.num_processed(), orig_count);
 493   guarantee(redirty.num_processed() == clear.num_processed(),
 494             err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
 495                     redirty.num_processed(), clear.num_processed()));
 496 
 497   CountNonCleanMemRegionClosure count3(this);
 498   ct_bs->mod_card_iterate(&count3);
 499   if (count3.n() != orig_count) {
 500     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 501                            orig_count, count3.n());
 502     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 503   }
 504 }
 505 
 506 // Private class members.
 507 
 508 G1CollectedHeap* G1CollectedHeap::_g1h;
 509 
 510 // Private methods.
 511 
 512 HeapRegion*
 513 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 514   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 515   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 516     if (!_secondary_free_list.is_empty()) {
 517       if (G1ConcRegionFreeingVerbose) {
 518         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 519                                "secondary_free_list has %u entries",
 520                                _secondary_free_list.length());
 521       }
 522       // It looks as if there are free regions available on the
 523       // secondary_free_list. Let's move them to the free_list and try
 524       // again to allocate from it.
 525       append_secondary_free_list();
 526 
 527       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 528              "empty we should have moved at least one entry to the free_list");
 529       HeapRegion* res = _free_list.remove_region(is_old);
 530       if (G1ConcRegionFreeingVerbose) {
 531         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 532                                "allocated "HR_FORMAT" from secondary_free_list",
 533                                HR_FORMAT_PARAMS(res));
 534       }
 535       return res;
 536     }
 537 
 538     // Wait here until we get notified either when (a) there are no
 539     // more free regions coming or (b) some regions have been moved on
 540     // the secondary_free_list.
 541     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 542   }
 543 
 544   if (G1ConcRegionFreeingVerbose) {
 545     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 546                            "could not allocate from secondary_free_list");
 547   }
 548   return NULL;
 549 }
 550 
 551 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 552   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 553          "the only time we use this to allocate a humongous region is "
 554          "when we are allocating a single humongous region");
 555 
 556   HeapRegion* res;
 557   if (G1StressConcRegionFreeing) {
 558     if (!_secondary_free_list.is_empty()) {
 559       if (G1ConcRegionFreeingVerbose) {
 560         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 561                                "forced to look at the secondary_free_list");
 562       }
 563       res = new_region_try_secondary_free_list(is_old);
 564       if (res != NULL) {
 565         return res;
 566       }
 567     }
 568   }
 569 
 570   res = _free_list.remove_region(is_old);
 571 
 572   if (res == NULL) {
 573     if (G1ConcRegionFreeingVerbose) {
 574       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 575                              "res == NULL, trying the secondary_free_list");
 576     }
 577     res = new_region_try_secondary_free_list(is_old);
 578   }
 579   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 580     // Currently, only attempts to allocate GC alloc regions set
 581     // do_expand to true. So, we should only reach here during a
 582     // safepoint. If this assumption changes we might have to
 583     // reconsider the use of _expand_heap_after_alloc_failure.
 584     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 585 
 586     ergo_verbose1(ErgoHeapSizing,
 587                   "attempt heap expansion",
 588                   ergo_format_reason("region allocation request failed")
 589                   ergo_format_byte("allocation request"),
 590                   word_size * HeapWordSize);
 591     if (expand(word_size * HeapWordSize)) {
 592       // Given that expand() succeeded in expanding the heap, and we
 593       // always expand the heap by an amount aligned to the heap
 594       // region size, the free list should in theory not be empty.
 595       // In either case remove_region() will check for NULL.
 596       res = _free_list.remove_region(is_old);
 597     } else {
 598       _expand_heap_after_alloc_failure = false;
 599     }
 600   }
 601   return res;
 602 }
 603 
 604 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 605                                                         size_t word_size) {
 606   assert(isHumongous(word_size), "word_size should be humongous");
 607   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 608 
 609   uint first = G1_NULL_HRS_INDEX;
 610   if (num_regions == 1) {
 611     // Only one region to allocate, no need to go through the slower
 612     // path. The caller will attempt the expansion if this fails, so
 613     // let's not try to expand here too.
 614     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 615     if (hr != NULL) {
 616       first = hr->hrs_index();
 617     } else {
 618       first = G1_NULL_HRS_INDEX;
 619     }
 620   } else {
 621     // We can't allocate humongous regions while cleanupComplete() is
 622     // running, since some of the regions we find to be empty might not
 623     // yet be added to the free list and it is not straightforward to
 624     // know which list they are on so that we can remove them. Note
 625     // that we only need to do this if we need to allocate more than
 626     // one region to satisfy the current humongous allocation
 627     // request. If we are only allocating one region we use the common
 628     // region allocation code (see above).
 629     wait_while_free_regions_coming();
 630     append_secondary_free_list_if_not_empty_with_lock();
 631 
 632     if (free_regions() >= num_regions) {
 633       first = _hrs.find_contiguous(num_regions);
 634       if (first != G1_NULL_HRS_INDEX) {
 635         for (uint i = first; i < first + num_regions; ++i) {
 636           HeapRegion* hr = region_at(i);
 637           assert(hr->is_empty(), "sanity");
 638           assert(is_on_master_free_list(hr), "sanity");
 639           hr->set_pending_removal(true);
 640         }
 641         _free_list.remove_all_pending(num_regions);
 642       }
 643     }
 644   }
 645   return first;
 646 }
 647 
 648 HeapWord*
 649 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 650                                                            uint num_regions,
 651                                                            size_t word_size) {
 652   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 653   assert(isHumongous(word_size), "word_size should be humongous");
 654   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 655 
 656   // Index of last region in the series + 1.
 657   uint last = first + num_regions;
 658 
 659   // We need to initialize the region(s) we just discovered. This is
 660   // a bit tricky given that it can happen concurrently with
 661   // refinement threads refining cards on these regions and
 662   // potentially wanting to refine the BOT as they are scanning
 663   // those cards (this can happen shortly after a cleanup; see CR
 664   // 6991377). So we have to set up the region(s) carefully and in
 665   // a specific order.
 666 
 667   // The word size sum of all the regions we will allocate.
 668   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 669   assert(word_size <= word_size_sum, "sanity");
 670 
 671   // This will be the "starts humongous" region.
 672   HeapRegion* first_hr = region_at(first);
 673   // The header of the new object will be placed at the bottom of
 674   // the first region.
 675   HeapWord* new_obj = first_hr->bottom();
 676   // This will be the new end of the first region in the series that
 677   // should also match the end of the last region in the series.
 678   HeapWord* new_end = new_obj + word_size_sum;
 679   // This will be the new top of the first region that will reflect
 680   // this allocation.
 681   HeapWord* new_top = new_obj + word_size;
 682 
 683   // First, we need to zero the header of the space that we will be
 684   // allocating. When we update top further down, some refinement
 685   // threads might try to scan the region. By zeroing the header we
 686   // ensure that any thread that will try to scan the region will
 687   // come across the zero klass word and bail out.
 688   //
 689   // NOTE: It would not have been correct to have used
 690   // CollectedHeap::fill_with_object() and make the space look like
 691   // an int array. The thread that is doing the allocation will
 692   // later update the object header to a potentially different array
 693   // type and, for a very short period of time, the klass and length
 694   // fields will be inconsistent. This could cause a refinement
 695   // thread to calculate the object size incorrectly.
 696   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 697 
 698   // We will set up the first region as "starts humongous". This
 699   // will also update the BOT covering all the regions to reflect
 700   // that there is a single object that starts at the bottom of the
 701   // first region.
 702   first_hr->set_startsHumongous(new_top, new_end);
 703 
 704   // Then, if there are any, we will set up the "continues
 705   // humongous" regions.
 706   HeapRegion* hr = NULL;
 707   for (uint i = first + 1; i < last; ++i) {
 708     hr = region_at(i);
 709     hr->set_continuesHumongous(first_hr);
 710   }
 711   // If we have "continues humongous" regions (hr != NULL), then the
 712   // end of the last one should match new_end.
 713   assert(hr == NULL || hr->end() == new_end, "sanity");
 714 
 715   // Up to this point no concurrent thread would have been able to
 716   // do any scanning on any region in this series. All the top
 717   // fields still point to bottom, so the intersection between
 718   // [bottom,top] and [card_start,card_end] will be empty. Before we
 719   // update the top fields, we'll do a storestore to make sure that
 720   // no thread sees the update to top before the zeroing of the
 721   // object header and the BOT initialization.
 722   OrderAccess::storestore();
 723 
 724   // Now that the BOT and the object header have been initialized,
 725   // we can update top of the "starts humongous" region.
 726   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 727          "new_top should be in this region");
 728   first_hr->set_top(new_top);
 729   if (_hr_printer.is_active()) {
 730     HeapWord* bottom = first_hr->bottom();
 731     HeapWord* end = first_hr->orig_end();
 732     if ((first + 1) == last) {
 733       // the series has a single humongous region
 734       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 735     } else {
 736       // the series has more than one humongous regions
 737       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 738     }
 739   }
 740 
 741   // Now, we will update the top fields of the "continues humongous"
 742   // regions. The reason we need to do this is that, otherwise,
 743   // these regions would look empty and this will confuse parts of
 744   // G1. For example, the code that looks for a consecutive number
 745   // of empty regions will consider them empty and try to
 746   // re-allocate them. We can extend is_empty() to also include
 747   // !continuesHumongous(), but it is easier to just update the top
 748   // fields here. The way we set top for all regions (i.e., top ==
 749   // end for all regions but the last one, top == new_top for the
 750   // last one) is actually used when we will free up the humongous
 751   // region in free_humongous_region().
 752   hr = NULL;
 753   for (uint i = first + 1; i < last; ++i) {
 754     hr = region_at(i);
 755     if ((i + 1) == last) {
 756       // last continues humongous region
 757       assert(hr->bottom() < new_top && new_top <= hr->end(),
 758              "new_top should fall on this region");
 759       hr->set_top(new_top);
 760       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 761     } else {
 762       // not last one
 763       assert(new_top > hr->end(), "new_top should be above this region");
 764       hr->set_top(hr->end());
 765       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 766     }
 767   }
 768   // If we have continues humongous regions (hr != NULL), then the
 769   // end of the last one should match new_end and its top should
 770   // match new_top.
 771   assert(hr == NULL ||
 772          (hr->end() == new_end && hr->top() == new_top), "sanity");
 773 
 774   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 775   _summary_bytes_used += first_hr->used();
 776   _humongous_set.add(first_hr);
 777 
 778   return new_obj;
 779 }
 780 
 781 // If could fit into free regions w/o expansion, try.
 782 // Otherwise, if can expand, do so.
 783 // Otherwise, if using ex regions might help, try with ex given back.
 784 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 785   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 786 
 787   verify_region_sets_optional();
 788 
 789   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 790   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 791   uint x_num = expansion_regions();
 792   uint fs = _hrs.free_suffix();
 793   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 794   if (first == G1_NULL_HRS_INDEX) {
 795     // The only thing we can do now is attempt expansion.
 796     if (fs + x_num >= num_regions) {
 797       // If the number of regions we're trying to allocate for this
 798       // object is at most the number of regions in the free suffix,
 799       // then the call to humongous_obj_allocate_find_first() above
 800       // should have succeeded and we wouldn't be here.
 801       //
 802       // We should only be trying to expand when the free suffix is
 803       // not sufficient for the object _and_ we have some expansion
 804       // room available.
 805       assert(num_regions > fs, "earlier allocation should have succeeded");
 806 
 807       ergo_verbose1(ErgoHeapSizing,
 808                     "attempt heap expansion",
 809                     ergo_format_reason("humongous allocation request failed")
 810                     ergo_format_byte("allocation request"),
 811                     word_size * HeapWordSize);
 812       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 813         // Even though the heap was expanded, it might not have
 814         // reached the desired size. So, we cannot assume that the
 815         // allocation will succeed.
 816         first = humongous_obj_allocate_find_first(num_regions, word_size);
 817       }
 818     }
 819   }
 820 
 821   HeapWord* result = NULL;
 822   if (first != G1_NULL_HRS_INDEX) {
 823     result =
 824       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 825     assert(result != NULL, "it should always return a valid result");
 826 
 827     // A successful humongous object allocation changes the used space
 828     // information of the old generation so we need to recalculate the
 829     // sizes and update the jstat counters here.
 830     g1mm()->update_sizes();
 831   }
 832 
 833   verify_region_sets_optional();
 834 
 835   return result;
 836 }
 837 
 838 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 839   assert_heap_not_locked_and_not_at_safepoint();
 840   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 841 
 842   unsigned int dummy_gc_count_before;
 843   int dummy_gclocker_retry_count = 0;
 844   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 845 }
 846 
 847 HeapWord*
 848 G1CollectedHeap::mem_allocate(size_t word_size,
 849                               bool*  gc_overhead_limit_was_exceeded) {
 850   assert_heap_not_locked_and_not_at_safepoint();
 851 
 852   // Loop until the allocation is satisfied, or unsatisfied after GC.
 853   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 854     unsigned int gc_count_before;
 855 
 856     HeapWord* result = NULL;
 857     if (!isHumongous(word_size)) {
 858       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 859     } else {
 860       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 861     }
 862     if (result != NULL) {
 863       return result;
 864     }
 865 
 866     // Create the garbage collection operation...
 867     VM_G1CollectForAllocation op(gc_count_before, word_size);
 868     // ...and get the VM thread to execute it.
 869     VMThread::execute(&op);
 870 
 871     if (op.prologue_succeeded() && op.pause_succeeded()) {
 872       // If the operation was successful we'll return the result even
 873       // if it is NULL. If the allocation attempt failed immediately
 874       // after a Full GC, it's unlikely we'll be able to allocate now.
 875       HeapWord* result = op.result();
 876       if (result != NULL && !isHumongous(word_size)) {
 877         // Allocations that take place on VM operations do not do any
 878         // card dirtying and we have to do it here. We only have to do
 879         // this for non-humongous allocations, though.
 880         dirty_young_block(result, word_size);
 881       }
 882       return result;
 883     } else {
 884       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 885         return NULL;
 886       }
 887       assert(op.result() == NULL,
 888              "the result should be NULL if the VM op did not succeed");
 889     }
 890 
 891     // Give a warning if we seem to be looping forever.
 892     if ((QueuedAllocationWarningCount > 0) &&
 893         (try_count % QueuedAllocationWarningCount == 0)) {
 894       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 895     }
 896   }
 897 
 898   ShouldNotReachHere();
 899   return NULL;
 900 }
 901 
 902 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 903                                            unsigned int *gc_count_before_ret,
 904                                            int* gclocker_retry_count_ret) {
 905   // Make sure you read the note in attempt_allocation_humongous().
 906 
 907   assert_heap_not_locked_and_not_at_safepoint();
 908   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 909          "be called for humongous allocation requests");
 910 
 911   // We should only get here after the first-level allocation attempt
 912   // (attempt_allocation()) failed to allocate.
 913 
 914   // We will loop until a) we manage to successfully perform the
 915   // allocation or b) we successfully schedule a collection which
 916   // fails to perform the allocation. b) is the only case when we'll
 917   // return NULL.
 918   HeapWord* result = NULL;
 919   for (int try_count = 1; /* we'll return */; try_count += 1) {
 920     bool should_try_gc;
 921     unsigned int gc_count_before;
 922 
 923     {
 924       MutexLockerEx x(Heap_lock);
 925 
 926       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 927                                                       false /* bot_updates */);
 928       if (result != NULL) {
 929         return result;
 930       }
 931 
 932       // If we reach here, attempt_allocation_locked() above failed to
 933       // allocate a new region. So the mutator alloc region should be NULL.
 934       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 935 
 936       if (GC_locker::is_active_and_needs_gc()) {
 937         if (g1_policy()->can_expand_young_list()) {
 938           // No need for an ergo verbose message here,
 939           // can_expand_young_list() does this when it returns true.
 940           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 941                                                       false /* bot_updates */);
 942           if (result != NULL) {
 943             return result;
 944           }
 945         }
 946         should_try_gc = false;
 947       } else {
 948         // The GCLocker may not be active but the GCLocker initiated
 949         // GC may not yet have been performed (GCLocker::needs_gc()
 950         // returns true). In this case we do not try this GC and
 951         // wait until the GCLocker initiated GC is performed, and
 952         // then retry the allocation.
 953         if (GC_locker::needs_gc()) {
 954           should_try_gc = false;
 955         } else {
 956           // Read the GC count while still holding the Heap_lock.
 957           gc_count_before = total_collections();
 958           should_try_gc = true;
 959         }
 960       }
 961     }
 962 
 963     if (should_try_gc) {
 964       bool succeeded;
 965       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 966           GCCause::_g1_inc_collection_pause);
 967       if (result != NULL) {
 968         assert(succeeded, "only way to get back a non-NULL result");
 969         return result;
 970       }
 971 
 972       if (succeeded) {
 973         // If we get here we successfully scheduled a collection which
 974         // failed to allocate. No point in trying to allocate
 975         // further. We'll just return NULL.
 976         MutexLockerEx x(Heap_lock);
 977         *gc_count_before_ret = total_collections();
 978         return NULL;
 979       }
 980     } else {
 981       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 982         MutexLockerEx x(Heap_lock);
 983         *gc_count_before_ret = total_collections();
 984         return NULL;
 985       }
 986       // The GCLocker is either active or the GCLocker initiated
 987       // GC has not yet been performed. Stall until it is and
 988       // then retry the allocation.
 989       GC_locker::stall_until_clear();
 990       (*gclocker_retry_count_ret) += 1;
 991     }
 992 
 993     // We can reach here if we were unsuccessful in scheduling a
 994     // collection (because another thread beat us to it) or if we were
 995     // stalled due to the GC locker. In either can we should retry the
 996     // allocation attempt in case another thread successfully
 997     // performed a collection and reclaimed enough space. We do the
 998     // first attempt (without holding the Heap_lock) here and the
 999     // follow-on attempt will be at the start of the next loop
1000     // iteration (after taking the Heap_lock).
1001     result = _mutator_alloc_region.attempt_allocation(word_size,
1002                                                       false /* bot_updates */);
1003     if (result != NULL) {
1004       return result;
1005     }
1006 
1007     // Give a warning if we seem to be looping forever.
1008     if ((QueuedAllocationWarningCount > 0) &&
1009         (try_count % QueuedAllocationWarningCount == 0)) {
1010       warning("G1CollectedHeap::attempt_allocation_slow() "
1011               "retries %d times", try_count);
1012     }
1013   }
1014 
1015   ShouldNotReachHere();
1016   return NULL;
1017 }
1018 
1019 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1020                                           unsigned int * gc_count_before_ret,
1021                                           int* gclocker_retry_count_ret) {
1022   // The structure of this method has a lot of similarities to
1023   // attempt_allocation_slow(). The reason these two were not merged
1024   // into a single one is that such a method would require several "if
1025   // allocation is not humongous do this, otherwise do that"
1026   // conditional paths which would obscure its flow. In fact, an early
1027   // version of this code did use a unified method which was harder to
1028   // follow and, as a result, it had subtle bugs that were hard to
1029   // track down. So keeping these two methods separate allows each to
1030   // be more readable. It will be good to keep these two in sync as
1031   // much as possible.
1032 
1033   assert_heap_not_locked_and_not_at_safepoint();
1034   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1035          "should only be called for humongous allocations");
1036 
1037   // Humongous objects can exhaust the heap quickly, so we should check if we
1038   // need to start a marking cycle at each humongous object allocation. We do
1039   // the check before we do the actual allocation. The reason for doing it
1040   // before the allocation is that we avoid having to keep track of the newly
1041   // allocated memory while we do a GC.
1042   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1043                                            word_size)) {
1044     collect(GCCause::_g1_humongous_allocation);
1045   }
1046 
1047   // We will loop until a) we manage to successfully perform the
1048   // allocation or b) we successfully schedule a collection which
1049   // fails to perform the allocation. b) is the only case when we'll
1050   // return NULL.
1051   HeapWord* result = NULL;
1052   for (int try_count = 1; /* we'll return */; try_count += 1) {
1053     bool should_try_gc;
1054     unsigned int gc_count_before;
1055 
1056     {
1057       MutexLockerEx x(Heap_lock);
1058 
1059       // Given that humongous objects are not allocated in young
1060       // regions, we'll first try to do the allocation without doing a
1061       // collection hoping that there's enough space in the heap.
1062       result = humongous_obj_allocate(word_size);
1063       if (result != NULL) {
1064         return result;
1065       }
1066 
1067       if (GC_locker::is_active_and_needs_gc()) {
1068         should_try_gc = false;
1069       } else {
1070          // The GCLocker may not be active but the GCLocker initiated
1071         // GC may not yet have been performed (GCLocker::needs_gc()
1072         // returns true). In this case we do not try this GC and
1073         // wait until the GCLocker initiated GC is performed, and
1074         // then retry the allocation.
1075         if (GC_locker::needs_gc()) {
1076           should_try_gc = false;
1077         } else {
1078           // Read the GC count while still holding the Heap_lock.
1079           gc_count_before = total_collections();
1080           should_try_gc = true;
1081         }
1082       }
1083     }
1084 
1085     if (should_try_gc) {
1086       // If we failed to allocate the humongous object, we should try to
1087       // do a collection pause (if we're allowed) in case it reclaims
1088       // enough space for the allocation to succeed after the pause.
1089 
1090       bool succeeded;
1091       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1092           GCCause::_g1_humongous_allocation);
1093       if (result != NULL) {
1094         assert(succeeded, "only way to get back a non-NULL result");
1095         return result;
1096       }
1097 
1098       if (succeeded) {
1099         // If we get here we successfully scheduled a collection which
1100         // failed to allocate. No point in trying to allocate
1101         // further. We'll just return NULL.
1102         MutexLockerEx x(Heap_lock);
1103         *gc_count_before_ret = total_collections();
1104         return NULL;
1105       }
1106     } else {
1107       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1108         MutexLockerEx x(Heap_lock);
1109         *gc_count_before_ret = total_collections();
1110         return NULL;
1111       }
1112       // The GCLocker is either active or the GCLocker initiated
1113       // GC has not yet been performed. Stall until it is and
1114       // then retry the allocation.
1115       GC_locker::stall_until_clear();
1116       (*gclocker_retry_count_ret) += 1;
1117     }
1118 
1119     // We can reach here if we were unsuccessful in scheduling a
1120     // collection (because another thread beat us to it) or if we were
1121     // stalled due to the GC locker. In either can we should retry the
1122     // allocation attempt in case another thread successfully
1123     // performed a collection and reclaimed enough space.  Give a
1124     // warning if we seem to be looping forever.
1125 
1126     if ((QueuedAllocationWarningCount > 0) &&
1127         (try_count % QueuedAllocationWarningCount == 0)) {
1128       warning("G1CollectedHeap::attempt_allocation_humongous() "
1129               "retries %d times", try_count);
1130     }
1131   }
1132 
1133   ShouldNotReachHere();
1134   return NULL;
1135 }
1136 
1137 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1138                                        bool expect_null_mutator_alloc_region) {
1139   assert_at_safepoint(true /* should_be_vm_thread */);
1140   assert(_mutator_alloc_region.get() == NULL ||
1141                                              !expect_null_mutator_alloc_region,
1142          "the current alloc region was unexpectedly found to be non-NULL");
1143 
1144   if (!isHumongous(word_size)) {
1145     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1146                                                       false /* bot_updates */);
1147   } else {
1148     HeapWord* result = humongous_obj_allocate(word_size);
1149     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1150       g1_policy()->set_initiate_conc_mark_if_possible();
1151     }
1152     return result;
1153   }
1154 
1155   ShouldNotReachHere();
1156 }
1157 
1158 class PostMCRemSetClearClosure: public HeapRegionClosure {
1159   G1CollectedHeap* _g1h;
1160   ModRefBarrierSet* _mr_bs;
1161 public:
1162   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1163     _g1h(g1h), _mr_bs(mr_bs) {}
1164 
1165   bool doHeapRegion(HeapRegion* r) {
1166     HeapRegionRemSet* hrrs = r->rem_set();
1167 
1168     if (r->continuesHumongous()) {
1169       // We'll assert that the strong code root list and RSet is empty
1170       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1171       assert(hrrs->occupied() == 0, "RSet should be empty");
1172       return false;
1173     }
1174 
1175     _g1h->reset_gc_time_stamps(r);
1176     hrrs->clear();
1177     // You might think here that we could clear just the cards
1178     // corresponding to the used region.  But no: if we leave a dirty card
1179     // in a region we might allocate into, then it would prevent that card
1180     // from being enqueued, and cause it to be missed.
1181     // Re: the performance cost: we shouldn't be doing full GC anyway!
1182     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1183 
1184     return false;
1185   }
1186 };
1187 
1188 void G1CollectedHeap::clear_rsets_post_compaction() {
1189   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1190   heap_region_iterate(&rs_clear);
1191 }
1192 
1193 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1194   G1CollectedHeap*   _g1h;
1195   UpdateRSOopClosure _cl;
1196   int                _worker_i;
1197 public:
1198   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1199     _cl(g1->g1_rem_set(), worker_i),
1200     _worker_i(worker_i),
1201     _g1h(g1)
1202   { }
1203 
1204   bool doHeapRegion(HeapRegion* r) {
1205     if (!r->continuesHumongous()) {
1206       _cl.set_from(r);
1207       r->oop_iterate(&_cl);
1208     }
1209     return false;
1210   }
1211 };
1212 
1213 class ParRebuildRSTask: public AbstractGangTask {
1214   G1CollectedHeap* _g1;
1215 public:
1216   ParRebuildRSTask(G1CollectedHeap* g1)
1217     : AbstractGangTask("ParRebuildRSTask"),
1218       _g1(g1)
1219   { }
1220 
1221   void work(uint worker_id) {
1222     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1223     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1224                                           _g1->workers()->active_workers(),
1225                                          HeapRegion::RebuildRSClaimValue);
1226   }
1227 };
1228 
1229 class PostCompactionPrinterClosure: public HeapRegionClosure {
1230 private:
1231   G1HRPrinter* _hr_printer;
1232 public:
1233   bool doHeapRegion(HeapRegion* hr) {
1234     assert(!hr->is_young(), "not expecting to find young regions");
1235     // We only generate output for non-empty regions.
1236     if (!hr->is_empty()) {
1237       if (!hr->isHumongous()) {
1238         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1239       } else if (hr->startsHumongous()) {
1240         if (hr->region_num() == 1) {
1241           // single humongous region
1242           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1243         } else {
1244           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1245         }
1246       } else {
1247         assert(hr->continuesHumongous(), "only way to get here");
1248         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1249       }
1250     }
1251     return false;
1252   }
1253 
1254   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1255     : _hr_printer(hr_printer) { }
1256 };
1257 
1258 void G1CollectedHeap::print_hrs_post_compaction() {
1259   PostCompactionPrinterClosure cl(hr_printer());
1260   heap_region_iterate(&cl);
1261 }
1262 
1263 bool G1CollectedHeap::do_collection(bool explicit_gc,
1264                                     bool clear_all_soft_refs,
1265                                     size_t word_size) {
1266   assert_at_safepoint(true /* should_be_vm_thread */);
1267 
1268   if (GC_locker::check_active_before_gc()) {
1269     return false;
1270   }
1271 
1272   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1273   gc_timer->register_gc_start();
1274 
1275   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1276   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1277 
1278   SvcGCMarker sgcm(SvcGCMarker::FULL);
1279   ResourceMark rm;
1280 
1281   print_heap_before_gc();
1282   trace_heap_before_gc(gc_tracer);
1283 
1284   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1285 
1286   verify_region_sets_optional();
1287 
1288   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1289                            collector_policy()->should_clear_all_soft_refs();
1290 
1291   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1292 
1293   {
1294     IsGCActiveMark x;
1295 
1296     // Timing
1297     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1298     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1299     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1300 
1301     {
1302       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1303       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1304       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1305 
1306       double start = os::elapsedTime();
1307       g1_policy()->record_full_collection_start();
1308 
1309       // Note: When we have a more flexible GC logging framework that
1310       // allows us to add optional attributes to a GC log record we
1311       // could consider timing and reporting how long we wait in the
1312       // following two methods.
1313       wait_while_free_regions_coming();
1314       // If we start the compaction before the CM threads finish
1315       // scanning the root regions we might trip them over as we'll
1316       // be moving objects / updating references. So let's wait until
1317       // they are done. By telling them to abort, they should complete
1318       // early.
1319       _cm->root_regions()->abort();
1320       _cm->root_regions()->wait_until_scan_finished();
1321       append_secondary_free_list_if_not_empty_with_lock();
1322 
1323       gc_prologue(true);
1324       increment_total_collections(true /* full gc */);
1325       increment_old_marking_cycles_started();
1326 
1327       assert(used() == recalculate_used(), "Should be equal");
1328 
1329       verify_before_gc();
1330 
1331       pre_full_gc_dump(gc_timer);
1332 
1333       COMPILER2_PRESENT(DerivedPointerTable::clear());
1334 
1335       // Disable discovery and empty the discovered lists
1336       // for the CM ref processor.
1337       ref_processor_cm()->disable_discovery();
1338       ref_processor_cm()->abandon_partial_discovery();
1339       ref_processor_cm()->verify_no_references_recorded();
1340 
1341       // Abandon current iterations of concurrent marking and concurrent
1342       // refinement, if any are in progress. We have to do this before
1343       // wait_until_scan_finished() below.
1344       concurrent_mark()->abort();
1345 
1346       // Make sure we'll choose a new allocation region afterwards.
1347       release_mutator_alloc_region();
1348       abandon_gc_alloc_regions();
1349       g1_rem_set()->cleanupHRRS();
1350 
1351       // We should call this after we retire any currently active alloc
1352       // regions so that all the ALLOC / RETIRE events are generated
1353       // before the start GC event.
1354       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1355 
1356       // We may have added regions to the current incremental collection
1357       // set between the last GC or pause and now. We need to clear the
1358       // incremental collection set and then start rebuilding it afresh
1359       // after this full GC.
1360       abandon_collection_set(g1_policy()->inc_cset_head());
1361       g1_policy()->clear_incremental_cset();
1362       g1_policy()->stop_incremental_cset_building();
1363 
1364       tear_down_region_sets(false /* free_list_only */);
1365       g1_policy()->set_gcs_are_young(true);
1366 
1367       // See the comments in g1CollectedHeap.hpp and
1368       // G1CollectedHeap::ref_processing_init() about
1369       // how reference processing currently works in G1.
1370 
1371       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1372       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1373 
1374       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1375       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1376 
1377       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1378       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1379 
1380       // Do collection work
1381       {
1382         HandleMark hm;  // Discard invalid handles created during gc
1383         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1384       }
1385 
1386       assert(free_regions() == 0, "we should not have added any free regions");
1387       rebuild_region_sets(false /* free_list_only */);
1388 
1389       // Enqueue any discovered reference objects that have
1390       // not been removed from the discovered lists.
1391       ref_processor_stw()->enqueue_discovered_references();
1392 
1393       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1394 
1395       MemoryService::track_memory_usage();
1396 
1397       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1398       ref_processor_stw()->verify_no_references_recorded();
1399 
1400       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1401       ClassLoaderDataGraph::purge();
1402       MetaspaceAux::verify_metrics();
1403 
1404       // Note: since we've just done a full GC, concurrent
1405       // marking is no longer active. Therefore we need not
1406       // re-enable reference discovery for the CM ref processor.
1407       // That will be done at the start of the next marking cycle.
1408       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1409       ref_processor_cm()->verify_no_references_recorded();
1410 
1411       reset_gc_time_stamp();
1412       // Since everything potentially moved, we will clear all remembered
1413       // sets, and clear all cards.  Later we will rebuild remembered
1414       // sets. We will also reset the GC time stamps of the regions.
1415       clear_rsets_post_compaction();
1416       check_gc_time_stamps();
1417 
1418       // Resize the heap if necessary.
1419       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1420 
1421       if (_hr_printer.is_active()) {
1422         // We should do this after we potentially resize the heap so
1423         // that all the COMMIT / UNCOMMIT events are generated before
1424         // the end GC event.
1425 
1426         print_hrs_post_compaction();
1427         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1428       }
1429 
1430       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1431       if (hot_card_cache->use_cache()) {
1432         hot_card_cache->reset_card_counts();
1433         hot_card_cache->reset_hot_cache();
1434       }
1435 
1436       // Rebuild remembered sets of all regions.
1437       if (G1CollectedHeap::use_parallel_gc_threads()) {
1438         uint n_workers =
1439           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1440                                                   workers()->active_workers(),
1441                                                   Threads::number_of_non_daemon_threads());
1442         assert(UseDynamicNumberOfGCThreads ||
1443                n_workers == workers()->total_workers(),
1444                "If not dynamic should be using all the  workers");
1445         workers()->set_active_workers(n_workers);
1446         // Set parallel threads in the heap (_n_par_threads) only
1447         // before a parallel phase and always reset it to 0 after
1448         // the phase so that the number of parallel threads does
1449         // no get carried forward to a serial phase where there
1450         // may be code that is "possibly_parallel".
1451         set_par_threads(n_workers);
1452 
1453         ParRebuildRSTask rebuild_rs_task(this);
1454         assert(check_heap_region_claim_values(
1455                HeapRegion::InitialClaimValue), "sanity check");
1456         assert(UseDynamicNumberOfGCThreads ||
1457                workers()->active_workers() == workers()->total_workers(),
1458                "Unless dynamic should use total workers");
1459         // Use the most recent number of  active workers
1460         assert(workers()->active_workers() > 0,
1461                "Active workers not properly set");
1462         set_par_threads(workers()->active_workers());
1463         workers()->run_task(&rebuild_rs_task);
1464         set_par_threads(0);
1465         assert(check_heap_region_claim_values(
1466                HeapRegion::RebuildRSClaimValue), "sanity check");
1467         reset_heap_region_claim_values();
1468       } else {
1469         RebuildRSOutOfRegionClosure rebuild_rs(this);
1470         heap_region_iterate(&rebuild_rs);
1471       }
1472 
1473       // Rebuild the strong code root lists for each region
1474       rebuild_strong_code_roots();
1475 
1476       if (true) { // FIXME
1477         MetaspaceGC::compute_new_size();
1478       }
1479 
1480 #ifdef TRACESPINNING
1481       ParallelTaskTerminator::print_termination_counts();
1482 #endif
1483 
1484       // Discard all rset updates
1485       JavaThread::dirty_card_queue_set().abandon_logs();
1486       assert(!G1DeferredRSUpdate
1487              || (G1DeferredRSUpdate &&
1488                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1489 
1490       _young_list->reset_sampled_info();
1491       // At this point there should be no regions in the
1492       // entire heap tagged as young.
1493       assert(check_young_list_empty(true /* check_heap */),
1494              "young list should be empty at this point");
1495 
1496       // Update the number of full collections that have been completed.
1497       increment_old_marking_cycles_completed(false /* concurrent */);
1498 
1499       _hrs.verify_optional();
1500       verify_region_sets_optional();
1501 
1502       verify_after_gc();
1503 
1504       // Start a new incremental collection set for the next pause
1505       assert(g1_policy()->collection_set() == NULL, "must be");
1506       g1_policy()->start_incremental_cset_building();
1507 
1508       clear_cset_fast_test();
1509 
1510       init_mutator_alloc_region();
1511 
1512       double end = os::elapsedTime();
1513       g1_policy()->record_full_collection_end();
1514 
1515       if (G1Log::fine()) {
1516         g1_policy()->print_heap_transition();
1517       }
1518 
1519       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1520       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1521       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1522       // before any GC notifications are raised.
1523       g1mm()->update_sizes();
1524 
1525       gc_epilogue(true);
1526     }
1527 
1528     if (G1Log::finer()) {
1529       g1_policy()->print_detailed_heap_transition(true /* full */);
1530     }
1531 
1532     print_heap_after_gc();
1533     trace_heap_after_gc(gc_tracer);
1534 
1535     post_full_gc_dump(gc_timer);
1536 
1537     gc_timer->register_gc_end();
1538     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1539   }
1540 
1541   return true;
1542 }
1543 
1544 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1545   // do_collection() will return whether it succeeded in performing
1546   // the GC. Currently, there is no facility on the
1547   // do_full_collection() API to notify the caller than the collection
1548   // did not succeed (e.g., because it was locked out by the GC
1549   // locker). So, right now, we'll ignore the return value.
1550   bool dummy = do_collection(true,                /* explicit_gc */
1551                              clear_all_soft_refs,
1552                              0                    /* word_size */);
1553 }
1554 
1555 // This code is mostly copied from TenuredGeneration.
1556 void
1557 G1CollectedHeap::
1558 resize_if_necessary_after_full_collection(size_t word_size) {
1559   // Include the current allocation, if any, and bytes that will be
1560   // pre-allocated to support collections, as "used".
1561   const size_t used_after_gc = used();
1562   const size_t capacity_after_gc = capacity();
1563   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1564 
1565   // This is enforced in arguments.cpp.
1566   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1567          "otherwise the code below doesn't make sense");
1568 
1569   // We don't have floating point command-line arguments
1570   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1571   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1572   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1573   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1574 
1575   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1576   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1577 
1578   // We have to be careful here as these two calculations can overflow
1579   // 32-bit size_t's.
1580   double used_after_gc_d = (double) used_after_gc;
1581   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1582   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1583 
1584   // Let's make sure that they are both under the max heap size, which
1585   // by default will make them fit into a size_t.
1586   double desired_capacity_upper_bound = (double) max_heap_size;
1587   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1588                                     desired_capacity_upper_bound);
1589   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1590                                     desired_capacity_upper_bound);
1591 
1592   // We can now safely turn them into size_t's.
1593   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1594   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1595 
1596   // This assert only makes sense here, before we adjust them
1597   // with respect to the min and max heap size.
1598   assert(minimum_desired_capacity <= maximum_desired_capacity,
1599          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1600                  "maximum_desired_capacity = "SIZE_FORMAT,
1601                  minimum_desired_capacity, maximum_desired_capacity));
1602 
1603   // Should not be greater than the heap max size. No need to adjust
1604   // it with respect to the heap min size as it's a lower bound (i.e.,
1605   // we'll try to make the capacity larger than it, not smaller).
1606   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1607   // Should not be less than the heap min size. No need to adjust it
1608   // with respect to the heap max size as it's an upper bound (i.e.,
1609   // we'll try to make the capacity smaller than it, not greater).
1610   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1611 
1612   if (capacity_after_gc < minimum_desired_capacity) {
1613     // Don't expand unless it's significant
1614     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1615     ergo_verbose4(ErgoHeapSizing,
1616                   "attempt heap expansion",
1617                   ergo_format_reason("capacity lower than "
1618                                      "min desired capacity after Full GC")
1619                   ergo_format_byte("capacity")
1620                   ergo_format_byte("occupancy")
1621                   ergo_format_byte_perc("min desired capacity"),
1622                   capacity_after_gc, used_after_gc,
1623                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1624     expand(expand_bytes);
1625 
1626     // No expansion, now see if we want to shrink
1627   } else if (capacity_after_gc > maximum_desired_capacity) {
1628     // Capacity too large, compute shrinking size
1629     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1630     ergo_verbose4(ErgoHeapSizing,
1631                   "attempt heap shrinking",
1632                   ergo_format_reason("capacity higher than "
1633                                      "max desired capacity after Full GC")
1634                   ergo_format_byte("capacity")
1635                   ergo_format_byte("occupancy")
1636                   ergo_format_byte_perc("max desired capacity"),
1637                   capacity_after_gc, used_after_gc,
1638                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1639     shrink(shrink_bytes);
1640   }
1641 }
1642 
1643 
1644 HeapWord*
1645 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1646                                            bool* succeeded) {
1647   assert_at_safepoint(true /* should_be_vm_thread */);
1648 
1649   *succeeded = true;
1650   // Let's attempt the allocation first.
1651   HeapWord* result =
1652     attempt_allocation_at_safepoint(word_size,
1653                                  false /* expect_null_mutator_alloc_region */);
1654   if (result != NULL) {
1655     assert(*succeeded, "sanity");
1656     return result;
1657   }
1658 
1659   // In a G1 heap, we're supposed to keep allocation from failing by
1660   // incremental pauses.  Therefore, at least for now, we'll favor
1661   // expansion over collection.  (This might change in the future if we can
1662   // do something smarter than full collection to satisfy a failed alloc.)
1663   result = expand_and_allocate(word_size);
1664   if (result != NULL) {
1665     assert(*succeeded, "sanity");
1666     return result;
1667   }
1668 
1669   // Expansion didn't work, we'll try to do a Full GC.
1670   bool gc_succeeded = do_collection(false, /* explicit_gc */
1671                                     false, /* clear_all_soft_refs */
1672                                     word_size);
1673   if (!gc_succeeded) {
1674     *succeeded = false;
1675     return NULL;
1676   }
1677 
1678   // Retry the allocation
1679   result = attempt_allocation_at_safepoint(word_size,
1680                                   true /* expect_null_mutator_alloc_region */);
1681   if (result != NULL) {
1682     assert(*succeeded, "sanity");
1683     return result;
1684   }
1685 
1686   // Then, try a Full GC that will collect all soft references.
1687   gc_succeeded = do_collection(false, /* explicit_gc */
1688                                true,  /* clear_all_soft_refs */
1689                                word_size);
1690   if (!gc_succeeded) {
1691     *succeeded = false;
1692     return NULL;
1693   }
1694 
1695   // Retry the allocation once more
1696   result = attempt_allocation_at_safepoint(word_size,
1697                                   true /* expect_null_mutator_alloc_region */);
1698   if (result != NULL) {
1699     assert(*succeeded, "sanity");
1700     return result;
1701   }
1702 
1703   assert(!collector_policy()->should_clear_all_soft_refs(),
1704          "Flag should have been handled and cleared prior to this point");
1705 
1706   // What else?  We might try synchronous finalization later.  If the total
1707   // space available is large enough for the allocation, then a more
1708   // complete compaction phase than we've tried so far might be
1709   // appropriate.
1710   assert(*succeeded, "sanity");
1711   return NULL;
1712 }
1713 
1714 // Attempting to expand the heap sufficiently
1715 // to support an allocation of the given "word_size".  If
1716 // successful, perform the allocation and return the address of the
1717 // allocated block, or else "NULL".
1718 
1719 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1720   assert_at_safepoint(true /* should_be_vm_thread */);
1721 
1722   verify_region_sets_optional();
1723 
1724   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1725   ergo_verbose1(ErgoHeapSizing,
1726                 "attempt heap expansion",
1727                 ergo_format_reason("allocation request failed")
1728                 ergo_format_byte("allocation request"),
1729                 word_size * HeapWordSize);
1730   if (expand(expand_bytes)) {
1731     _hrs.verify_optional();
1732     verify_region_sets_optional();
1733     return attempt_allocation_at_safepoint(word_size,
1734                                  false /* expect_null_mutator_alloc_region */);
1735   }
1736   return NULL;
1737 }
1738 
1739 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1740                                              HeapWord* new_end) {
1741   assert(old_end != new_end, "don't call this otherwise");
1742   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1743 
1744   // Update the committed mem region.
1745   _g1_committed.set_end(new_end);
1746   // Tell the card table about the update.
1747   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1748   // Tell the BOT about the update.
1749   _bot_shared->resize(_g1_committed.word_size());
1750   // Tell the hot card cache about the update
1751   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1752 }
1753 
1754 bool G1CollectedHeap::expand(size_t expand_bytes) {
1755   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1756   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1757                                        HeapRegion::GrainBytes);
1758   ergo_verbose2(ErgoHeapSizing,
1759                 "expand the heap",
1760                 ergo_format_byte("requested expansion amount")
1761                 ergo_format_byte("attempted expansion amount"),
1762                 expand_bytes, aligned_expand_bytes);
1763 
1764   if (_g1_storage.uncommitted_size() == 0) {
1765     ergo_verbose0(ErgoHeapSizing,
1766                       "did not expand the heap",
1767                       ergo_format_reason("heap already fully expanded"));
1768     return false;
1769   }
1770 
1771   // First commit the memory.
1772   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1773   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1774   if (successful) {
1775     // Then propagate this update to the necessary data structures.
1776     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1777     update_committed_space(old_end, new_end);
1778 
1779     FreeRegionList expansion_list("Local Expansion List");
1780     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1781     assert(mr.start() == old_end, "post-condition");
1782     // mr might be a smaller region than what was requested if
1783     // expand_by() was unable to allocate the HeapRegion instances
1784     assert(mr.end() <= new_end, "post-condition");
1785 
1786     size_t actual_expand_bytes = mr.byte_size();
1787     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1788     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1789            "post-condition");
1790     if (actual_expand_bytes < aligned_expand_bytes) {
1791       // We could not expand _hrs to the desired size. In this case we
1792       // need to shrink the committed space accordingly.
1793       assert(mr.end() < new_end, "invariant");
1794 
1795       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1796       // First uncommit the memory.
1797       _g1_storage.shrink_by(diff_bytes);
1798       // Then propagate this update to the necessary data structures.
1799       update_committed_space(new_end, mr.end());
1800     }
1801     _free_list.add_as_tail(&expansion_list);
1802 
1803     if (_hr_printer.is_active()) {
1804       HeapWord* curr = mr.start();
1805       while (curr < mr.end()) {
1806         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1807         _hr_printer.commit(curr, curr_end);
1808         curr = curr_end;
1809       }
1810       assert(curr == mr.end(), "post-condition");
1811     }
1812     g1_policy()->record_new_heap_size(n_regions());
1813   } else {
1814     ergo_verbose0(ErgoHeapSizing,
1815                   "did not expand the heap",
1816                   ergo_format_reason("heap expansion operation failed"));
1817     // The expansion of the virtual storage space was unsuccessful.
1818     // Let's see if it was because we ran out of swap.
1819     if (G1ExitOnExpansionFailure &&
1820         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1821       // We had head room...
1822       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1823     }
1824   }
1825   return successful;
1826 }
1827 
1828 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1829   size_t aligned_shrink_bytes =
1830     ReservedSpace::page_align_size_down(shrink_bytes);
1831   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1832                                          HeapRegion::GrainBytes);
1833   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1834 
1835   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1836   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1837   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1838 
1839   ergo_verbose3(ErgoHeapSizing,
1840                 "shrink the heap",
1841                 ergo_format_byte("requested shrinking amount")
1842                 ergo_format_byte("aligned shrinking amount")
1843                 ergo_format_byte("attempted shrinking amount"),
1844                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1845   if (num_regions_removed > 0) {
1846     _g1_storage.shrink_by(shrunk_bytes);
1847     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1848 
1849     if (_hr_printer.is_active()) {
1850       HeapWord* curr = old_end;
1851       while (curr > new_end) {
1852         HeapWord* curr_end = curr;
1853         curr -= HeapRegion::GrainWords;
1854         _hr_printer.uncommit(curr, curr_end);
1855       }
1856     }
1857 
1858     _expansion_regions += num_regions_removed;
1859     update_committed_space(old_end, new_end);
1860     HeapRegionRemSet::shrink_heap(n_regions());
1861     g1_policy()->record_new_heap_size(n_regions());
1862   } else {
1863     ergo_verbose0(ErgoHeapSizing,
1864                   "did not shrink the heap",
1865                   ergo_format_reason("heap shrinking operation failed"));
1866   }
1867 }
1868 
1869 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1870   verify_region_sets_optional();
1871 
1872   // We should only reach here at the end of a Full GC which means we
1873   // should not not be holding to any GC alloc regions. The method
1874   // below will make sure of that and do any remaining clean up.
1875   abandon_gc_alloc_regions();
1876 
1877   // Instead of tearing down / rebuilding the free lists here, we
1878   // could instead use the remove_all_pending() method on free_list to
1879   // remove only the ones that we need to remove.
1880   tear_down_region_sets(true /* free_list_only */);
1881   shrink_helper(shrink_bytes);
1882   rebuild_region_sets(true /* free_list_only */);
1883 
1884   _hrs.verify_optional();
1885   verify_region_sets_optional();
1886 }
1887 
1888 // Public methods.
1889 
1890 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1891 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1892 #endif // _MSC_VER
1893 
1894 
1895 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1896   SharedHeap(policy_),
1897   _g1_policy(policy_),
1898   _dirty_card_queue_set(false),
1899   _into_cset_dirty_card_queue_set(false),
1900   _is_alive_closure_cm(this),
1901   _is_alive_closure_stw(this),
1902   _ref_processor_cm(NULL),
1903   _ref_processor_stw(NULL),
1904   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1905   _bot_shared(NULL),
1906   _evac_failure_scan_stack(NULL),
1907   _mark_in_progress(false),
1908   _cg1r(NULL), _summary_bytes_used(0),
1909   _g1mm(NULL),
1910   _refine_cte_cl(NULL),
1911   _full_collection(false),
1912   _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1913   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1914   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1915   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1916   _free_regions_coming(false),
1917   _young_list(new YoungList(this)),
1918   _gc_time_stamp(0),
1919   _retained_old_gc_alloc_region(NULL),
1920   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1921   _old_plab_stats(OldPLABSize, PLABWeight),
1922   _expand_heap_after_alloc_failure(true),
1923   _surviving_young_words(NULL),
1924   _old_marking_cycles_started(0),
1925   _old_marking_cycles_completed(0),
1926   _concurrent_cycle_started(false),
1927   _in_cset_fast_test(),
1928   _dirty_cards_region_list(NULL),
1929   _worker_cset_start_region(NULL),
1930   _worker_cset_start_region_time_stamp(NULL),
1931   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1932   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1933   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1934   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1935 
1936   _g1h = this;
1937   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1938     vm_exit_during_initialization("Failed necessary allocation.");
1939   }
1940 
1941   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1942 
1943   int n_queues = MAX2((int)ParallelGCThreads, 1);
1944   _task_queues = new RefToScanQueueSet(n_queues);
1945 
1946   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1947   assert(n_rem_sets > 0, "Invariant.");
1948 
1949   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1950   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1951   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1952 
1953   for (int i = 0; i < n_queues; i++) {
1954     RefToScanQueue* q = new RefToScanQueue();
1955     q->initialize();
1956     _task_queues->register_queue(i, q);
1957     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1958   }
1959   clear_cset_start_regions();
1960 
1961   // Initialize the G1EvacuationFailureALot counters and flags.
1962   NOT_PRODUCT(reset_evacuation_should_fail();)
1963 
1964   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1965 }
1966 
1967 jint G1CollectedHeap::initialize() {
1968   CollectedHeap::pre_initialize();
1969   os::enable_vtime();
1970 
1971   G1Log::init();
1972 
1973   // Necessary to satisfy locking discipline assertions.
1974 
1975   MutexLocker x(Heap_lock);
1976 
1977   // We have to initialize the printer before committing the heap, as
1978   // it will be used then.
1979   _hr_printer.set_active(G1PrintHeapRegions);
1980 
1981   // While there are no constraints in the GC code that HeapWordSize
1982   // be any particular value, there are multiple other areas in the
1983   // system which believe this to be true (e.g. oop->object_size in some
1984   // cases incorrectly returns the size in wordSize units rather than
1985   // HeapWordSize).
1986   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1987 
1988   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1989   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1990   size_t heap_alignment = collector_policy()->heap_alignment();
1991 
1992   // Ensure that the sizes are properly aligned.
1993   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1994   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1995   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1996 
1997   _refine_cte_cl = new RefineCardTableEntryClosure();
1998 
1999   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2000 
2001   // Reserve the maximum.
2002 
2003   // When compressed oops are enabled, the preferred heap base
2004   // is calculated by subtracting the requested size from the
2005   // 32Gb boundary and using the result as the base address for
2006   // heap reservation. If the requested size is not aligned to
2007   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2008   // into the ReservedHeapSpace constructor) then the actual
2009   // base of the reserved heap may end up differing from the
2010   // address that was requested (i.e. the preferred heap base).
2011   // If this happens then we could end up using a non-optimal
2012   // compressed oops mode.
2013 
2014   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2015                                                  heap_alignment);
2016 
2017   // It is important to do this in a way such that concurrent readers can't
2018   // temporarily think something is in the heap.  (I've actually seen this
2019   // happen in asserts: DLD.)
2020   _reserved.set_word_size(0);
2021   _reserved.set_start((HeapWord*)heap_rs.base());
2022   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2023 
2024   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2025 
2026   // Create the gen rem set (and barrier set) for the entire reserved region.
2027   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2028   set_barrier_set(rem_set()->bs());
2029   if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2030     vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2031     return JNI_ENOMEM;
2032   }
2033 
2034   // Also create a G1 rem set.
2035   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2036 
2037   // Carve out the G1 part of the heap.
2038 
2039   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2040   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2041                            g1_rs.size()/HeapWordSize);
2042 
2043   _g1_storage.initialize(g1_rs, 0);
2044   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2045   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2046                   (HeapWord*) _g1_reserved.end());
2047   assert(_hrs.max_length() == _expansion_regions,
2048          err_msg("max length: %u expansion regions: %u",
2049                  _hrs.max_length(), _expansion_regions));
2050 
2051   // Do later initialization work for concurrent refinement.
2052   _cg1r->init();
2053 
2054   // 6843694 - ensure that the maximum region index can fit
2055   // in the remembered set structures.
2056   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2057   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2058 
2059   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2060   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2061   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2062             "too many cards per region");
2063 
2064   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2065 
2066   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2067                                              heap_word_size(init_byte_size));
2068 
2069   _g1h = this;
2070 
2071   _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2072 
2073   // Create the ConcurrentMark data structure and thread.
2074   // (Must do this late, so that "max_regions" is defined.)
2075   _cm = new ConcurrentMark(this, heap_rs);
2076   if (_cm == NULL || !_cm->completed_initialization()) {
2077     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2078     return JNI_ENOMEM;
2079   }
2080   _cmThread = _cm->cmThread();
2081 
2082   // Initialize the from_card cache structure of HeapRegionRemSet.
2083   HeapRegionRemSet::init_heap(max_regions());
2084 
2085   // Now expand into the initial heap size.
2086   if (!expand(init_byte_size)) {
2087     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2088     return JNI_ENOMEM;
2089   }
2090 
2091   // Perform any initialization actions delegated to the policy.
2092   g1_policy()->init();
2093 
2094   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2095                                                SATB_Q_FL_lock,
2096                                                G1SATBProcessCompletedThreshold,
2097                                                Shared_SATB_Q_lock);
2098 
2099   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2100                                                 DirtyCardQ_CBL_mon,
2101                                                 DirtyCardQ_FL_lock,
2102                                                 concurrent_g1_refine()->yellow_zone(),
2103                                                 concurrent_g1_refine()->red_zone(),
2104                                                 Shared_DirtyCardQ_lock);
2105 
2106   if (G1DeferredRSUpdate) {
2107     dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2108                                       DirtyCardQ_CBL_mon,
2109                                       DirtyCardQ_FL_lock,
2110                                       -1, // never trigger processing
2111                                       -1, // no limit on length
2112                                       Shared_DirtyCardQ_lock,
2113                                       &JavaThread::dirty_card_queue_set());
2114   }
2115 
2116   // Initialize the card queue set used to hold cards containing
2117   // references into the collection set.
2118   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2119                                              DirtyCardQ_CBL_mon,
2120                                              DirtyCardQ_FL_lock,
2121                                              -1, // never trigger processing
2122                                              -1, // no limit on length
2123                                              Shared_DirtyCardQ_lock,
2124                                              &JavaThread::dirty_card_queue_set());
2125 
2126   // In case we're keeping closure specialization stats, initialize those
2127   // counts and that mechanism.
2128   SpecializationStats::clear();
2129 
2130   // Here we allocate the dummy full region that is required by the
2131   // G1AllocRegion class. If we don't pass an address in the reserved
2132   // space here, lots of asserts fire.
2133 
2134   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2135                                              _g1_reserved.start());
2136   // We'll re-use the same region whether the alloc region will
2137   // require BOT updates or not and, if it doesn't, then a non-young
2138   // region will complain that it cannot support allocations without
2139   // BOT updates. So we'll tag the dummy region as young to avoid that.
2140   dummy_region->set_young();
2141   // Make sure it's full.
2142   dummy_region->set_top(dummy_region->end());
2143   G1AllocRegion::setup(this, dummy_region);
2144 
2145   init_mutator_alloc_region();
2146 
2147   // Do create of the monitoring and management support so that
2148   // values in the heap have been properly initialized.
2149   _g1mm = new G1MonitoringSupport(this);
2150 
2151   G1StringDedup::initialize();
2152 
2153   return JNI_OK;
2154 }
2155 
2156 void G1CollectedHeap::stop() {
2157   // Stop all concurrent threads. We do this to make sure these threads
2158   // do not continue to execute and access resources (e.g. gclog_or_tty)
2159   // that are destroyed during shutdown.
2160   _cg1r->stop();
2161   _cmThread->stop();
2162   if (G1StringDedup::is_enabled()) {
2163     G1StringDedup::stop();
2164   }
2165 }
2166 
2167 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2168   return HeapRegion::max_region_size();
2169 }
2170 
2171 void G1CollectedHeap::ref_processing_init() {
2172   // Reference processing in G1 currently works as follows:
2173   //
2174   // * There are two reference processor instances. One is
2175   //   used to record and process discovered references
2176   //   during concurrent marking; the other is used to
2177   //   record and process references during STW pauses
2178   //   (both full and incremental).
2179   // * Both ref processors need to 'span' the entire heap as
2180   //   the regions in the collection set may be dotted around.
2181   //
2182   // * For the concurrent marking ref processor:
2183   //   * Reference discovery is enabled at initial marking.
2184   //   * Reference discovery is disabled and the discovered
2185   //     references processed etc during remarking.
2186   //   * Reference discovery is MT (see below).
2187   //   * Reference discovery requires a barrier (see below).
2188   //   * Reference processing may or may not be MT
2189   //     (depending on the value of ParallelRefProcEnabled
2190   //     and ParallelGCThreads).
2191   //   * A full GC disables reference discovery by the CM
2192   //     ref processor and abandons any entries on it's
2193   //     discovered lists.
2194   //
2195   // * For the STW processor:
2196   //   * Non MT discovery is enabled at the start of a full GC.
2197   //   * Processing and enqueueing during a full GC is non-MT.
2198   //   * During a full GC, references are processed after marking.
2199   //
2200   //   * Discovery (may or may not be MT) is enabled at the start
2201   //     of an incremental evacuation pause.
2202   //   * References are processed near the end of a STW evacuation pause.
2203   //   * For both types of GC:
2204   //     * Discovery is atomic - i.e. not concurrent.
2205   //     * Reference discovery will not need a barrier.
2206 
2207   SharedHeap::ref_processing_init();
2208   MemRegion mr = reserved_region();
2209 
2210   // Concurrent Mark ref processor
2211   _ref_processor_cm =
2212     new ReferenceProcessor(mr,    // span
2213                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2214                                 // mt processing
2215                            (int) ParallelGCThreads,
2216                                 // degree of mt processing
2217                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2218                                 // mt discovery
2219                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2220                                 // degree of mt discovery
2221                            false,
2222                                 // Reference discovery is not atomic
2223                            &_is_alive_closure_cm);
2224                                 // is alive closure
2225                                 // (for efficiency/performance)
2226 
2227   // STW ref processor
2228   _ref_processor_stw =
2229     new ReferenceProcessor(mr,    // span
2230                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2231                                 // mt processing
2232                            MAX2((int)ParallelGCThreads, 1),
2233                                 // degree of mt processing
2234                            (ParallelGCThreads > 1),
2235                                 // mt discovery
2236                            MAX2((int)ParallelGCThreads, 1),
2237                                 // degree of mt discovery
2238                            true,
2239                                 // Reference discovery is atomic
2240                            &_is_alive_closure_stw);
2241                                 // is alive closure
2242                                 // (for efficiency/performance)
2243 }
2244 
2245 size_t G1CollectedHeap::capacity() const {
2246   return _g1_committed.byte_size();
2247 }
2248 
2249 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2250   assert(!hr->continuesHumongous(), "pre-condition");
2251   hr->reset_gc_time_stamp();
2252   if (hr->startsHumongous()) {
2253     uint first_index = hr->hrs_index() + 1;
2254     uint last_index = hr->last_hc_index();
2255     for (uint i = first_index; i < last_index; i += 1) {
2256       HeapRegion* chr = region_at(i);
2257       assert(chr->continuesHumongous(), "sanity");
2258       chr->reset_gc_time_stamp();
2259     }
2260   }
2261 }
2262 
2263 #ifndef PRODUCT
2264 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2265 private:
2266   unsigned _gc_time_stamp;
2267   bool _failures;
2268 
2269 public:
2270   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2271     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2272 
2273   virtual bool doHeapRegion(HeapRegion* hr) {
2274     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2275     if (_gc_time_stamp != region_gc_time_stamp) {
2276       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2277                              "expected %d", HR_FORMAT_PARAMS(hr),
2278                              region_gc_time_stamp, _gc_time_stamp);
2279       _failures = true;
2280     }
2281     return false;
2282   }
2283 
2284   bool failures() { return _failures; }
2285 };
2286 
2287 void G1CollectedHeap::check_gc_time_stamps() {
2288   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2289   heap_region_iterate(&cl);
2290   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2291 }
2292 #endif // PRODUCT
2293 
2294 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2295                                                  DirtyCardQueue* into_cset_dcq,
2296                                                  bool concurrent,
2297                                                  uint worker_i) {
2298   // Clean cards in the hot card cache
2299   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2300   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2301 
2302   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2303   int n_completed_buffers = 0;
2304   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2305     n_completed_buffers++;
2306   }
2307   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2308   dcqs.clear_n_completed_buffers();
2309   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2310 }
2311 
2312 
2313 // Computes the sum of the storage used by the various regions.
2314 
2315 size_t G1CollectedHeap::used() const {
2316   assert(Heap_lock->owner() != NULL,
2317          "Should be owned on this thread's behalf.");
2318   size_t result = _summary_bytes_used;
2319   // Read only once in case it is set to NULL concurrently
2320   HeapRegion* hr = _mutator_alloc_region.get();
2321   if (hr != NULL)
2322     result += hr->used();
2323   return result;
2324 }
2325 
2326 size_t G1CollectedHeap::used_unlocked() const {
2327   size_t result = _summary_bytes_used;
2328   return result;
2329 }
2330 
2331 class SumUsedClosure: public HeapRegionClosure {
2332   size_t _used;
2333 public:
2334   SumUsedClosure() : _used(0) {}
2335   bool doHeapRegion(HeapRegion* r) {
2336     if (!r->continuesHumongous()) {
2337       _used += r->used();
2338     }
2339     return false;
2340   }
2341   size_t result() { return _used; }
2342 };
2343 
2344 size_t G1CollectedHeap::recalculate_used() const {
2345   double recalculate_used_start = os::elapsedTime();
2346 
2347   SumUsedClosure blk;
2348   heap_region_iterate(&blk);
2349 
2350   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2351   return blk.result();
2352 }
2353 
2354 size_t G1CollectedHeap::unsafe_max_alloc() {
2355   if (free_regions() > 0) return HeapRegion::GrainBytes;
2356   // otherwise, is there space in the current allocation region?
2357 
2358   // We need to store the current allocation region in a local variable
2359   // here. The problem is that this method doesn't take any locks and
2360   // there may be other threads which overwrite the current allocation
2361   // region field. attempt_allocation(), for example, sets it to NULL
2362   // and this can happen *after* the NULL check here but before the call
2363   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2364   // to be a problem in the optimized build, since the two loads of the
2365   // current allocation region field are optimized away.
2366   HeapRegion* hr = _mutator_alloc_region.get();
2367   if (hr == NULL) {
2368     return 0;
2369   }
2370   return hr->free();
2371 }
2372 
2373 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2374   switch (cause) {
2375     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2376     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2377     case GCCause::_g1_humongous_allocation: return true;
2378     default:                                return false;
2379   }
2380 }
2381 
2382 #ifndef PRODUCT
2383 void G1CollectedHeap::allocate_dummy_regions() {
2384   // Let's fill up most of the region
2385   size_t word_size = HeapRegion::GrainWords - 1024;
2386   // And as a result the region we'll allocate will be humongous.
2387   guarantee(isHumongous(word_size), "sanity");
2388 
2389   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2390     // Let's use the existing mechanism for the allocation
2391     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2392     if (dummy_obj != NULL) {
2393       MemRegion mr(dummy_obj, word_size);
2394       CollectedHeap::fill_with_object(mr);
2395     } else {
2396       // If we can't allocate once, we probably cannot allocate
2397       // again. Let's get out of the loop.
2398       break;
2399     }
2400   }
2401 }
2402 #endif // !PRODUCT
2403 
2404 void G1CollectedHeap::increment_old_marking_cycles_started() {
2405   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2406     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2407     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2408     _old_marking_cycles_started, _old_marking_cycles_completed));
2409 
2410   _old_marking_cycles_started++;
2411 }
2412 
2413 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2414   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2415 
2416   // We assume that if concurrent == true, then the caller is a
2417   // concurrent thread that was joined the Suspendible Thread
2418   // Set. If there's ever a cheap way to check this, we should add an
2419   // assert here.
2420 
2421   // Given that this method is called at the end of a Full GC or of a
2422   // concurrent cycle, and those can be nested (i.e., a Full GC can
2423   // interrupt a concurrent cycle), the number of full collections
2424   // completed should be either one (in the case where there was no
2425   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2426   // behind the number of full collections started.
2427 
2428   // This is the case for the inner caller, i.e. a Full GC.
2429   assert(concurrent ||
2430          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2431          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2432          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2433                  "is inconsistent with _old_marking_cycles_completed = %u",
2434                  _old_marking_cycles_started, _old_marking_cycles_completed));
2435 
2436   // This is the case for the outer caller, i.e. the concurrent cycle.
2437   assert(!concurrent ||
2438          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2439          err_msg("for outer caller (concurrent cycle): "
2440                  "_old_marking_cycles_started = %u "
2441                  "is inconsistent with _old_marking_cycles_completed = %u",
2442                  _old_marking_cycles_started, _old_marking_cycles_completed));
2443 
2444   _old_marking_cycles_completed += 1;
2445 
2446   // We need to clear the "in_progress" flag in the CM thread before
2447   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2448   // is set) so that if a waiter requests another System.gc() it doesn't
2449   // incorrectly see that a marking cycle is still in progress.
2450   if (concurrent) {
2451     _cmThread->clear_in_progress();
2452   }
2453 
2454   // This notify_all() will ensure that a thread that called
2455   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2456   // and it's waiting for a full GC to finish will be woken up. It is
2457   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2458   FullGCCount_lock->notify_all();
2459 }
2460 
2461 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2462   _concurrent_cycle_started = true;
2463   _gc_timer_cm->register_gc_start(start_time);
2464 
2465   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2466   trace_heap_before_gc(_gc_tracer_cm);
2467 }
2468 
2469 void G1CollectedHeap::register_concurrent_cycle_end() {
2470   if (_concurrent_cycle_started) {
2471     if (_cm->has_aborted()) {
2472       _gc_tracer_cm->report_concurrent_mode_failure();
2473     }
2474 
2475     _gc_timer_cm->register_gc_end();
2476     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2477 
2478     _concurrent_cycle_started = false;
2479   }
2480 }
2481 
2482 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2483   if (_concurrent_cycle_started) {
2484     trace_heap_after_gc(_gc_tracer_cm);
2485   }
2486 }
2487 
2488 G1YCType G1CollectedHeap::yc_type() {
2489   bool is_young = g1_policy()->gcs_are_young();
2490   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2491   bool is_during_mark = mark_in_progress();
2492 
2493   if (is_initial_mark) {
2494     return InitialMark;
2495   } else if (is_during_mark) {
2496     return DuringMark;
2497   } else if (is_young) {
2498     return Normal;
2499   } else {
2500     return Mixed;
2501   }
2502 }
2503 
2504 void G1CollectedHeap::collect(GCCause::Cause cause) {
2505   assert_heap_not_locked();
2506 
2507   unsigned int gc_count_before;
2508   unsigned int old_marking_count_before;
2509   bool retry_gc;
2510 
2511   do {
2512     retry_gc = false;
2513 
2514     {
2515       MutexLocker ml(Heap_lock);
2516 
2517       // Read the GC count while holding the Heap_lock
2518       gc_count_before = total_collections();
2519       old_marking_count_before = _old_marking_cycles_started;
2520     }
2521 
2522     if (should_do_concurrent_full_gc(cause)) {
2523       // Schedule an initial-mark evacuation pause that will start a
2524       // concurrent cycle. We're setting word_size to 0 which means that
2525       // we are not requesting a post-GC allocation.
2526       VM_G1IncCollectionPause op(gc_count_before,
2527                                  0,     /* word_size */
2528                                  true,  /* should_initiate_conc_mark */
2529                                  g1_policy()->max_pause_time_ms(),
2530                                  cause);
2531 
2532       VMThread::execute(&op);
2533       if (!op.pause_succeeded()) {
2534         if (old_marking_count_before == _old_marking_cycles_started) {
2535           retry_gc = op.should_retry_gc();
2536         } else {
2537           // A Full GC happened while we were trying to schedule the
2538           // initial-mark GC. No point in starting a new cycle given
2539           // that the whole heap was collected anyway.
2540         }
2541 
2542         if (retry_gc) {
2543           if (GC_locker::is_active_and_needs_gc()) {
2544             GC_locker::stall_until_clear();
2545           }
2546         }
2547       }
2548     } else {
2549       if (cause == GCCause::_gc_locker
2550           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2551 
2552         // Schedule a standard evacuation pause. We're setting word_size
2553         // to 0 which means that we are not requesting a post-GC allocation.
2554         VM_G1IncCollectionPause op(gc_count_before,
2555                                    0,     /* word_size */
2556                                    false, /* should_initiate_conc_mark */
2557                                    g1_policy()->max_pause_time_ms(),
2558                                    cause);
2559         VMThread::execute(&op);
2560       } else {
2561         // Schedule a Full GC.
2562         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2563         VMThread::execute(&op);
2564       }
2565     }
2566   } while (retry_gc);
2567 }
2568 
2569 bool G1CollectedHeap::is_in(const void* p) const {
2570   if (_g1_committed.contains(p)) {
2571     // Given that we know that p is in the committed space,
2572     // heap_region_containing_raw() should successfully
2573     // return the containing region.
2574     HeapRegion* hr = heap_region_containing_raw(p);
2575     return hr->is_in(p);
2576   } else {
2577     return false;
2578   }
2579 }
2580 
2581 // Iteration functions.
2582 
2583 // Iterates an OopClosure over all ref-containing fields of objects
2584 // within a HeapRegion.
2585 
2586 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2587   MemRegion _mr;
2588   ExtendedOopClosure* _cl;
2589 public:
2590   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2591     : _mr(mr), _cl(cl) {}
2592   bool doHeapRegion(HeapRegion* r) {
2593     if (!r->continuesHumongous()) {
2594       r->oop_iterate(_cl);
2595     }
2596     return false;
2597   }
2598 };
2599 
2600 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2601   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2602   heap_region_iterate(&blk);
2603 }
2604 
2605 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2606   IterateOopClosureRegionClosure blk(mr, cl);
2607   heap_region_iterate(&blk);
2608 }
2609 
2610 // Iterates an ObjectClosure over all objects within a HeapRegion.
2611 
2612 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2613   ObjectClosure* _cl;
2614 public:
2615   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2616   bool doHeapRegion(HeapRegion* r) {
2617     if (! r->continuesHumongous()) {
2618       r->object_iterate(_cl);
2619     }
2620     return false;
2621   }
2622 };
2623 
2624 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2625   IterateObjectClosureRegionClosure blk(cl);
2626   heap_region_iterate(&blk);
2627 }
2628 
2629 // Calls a SpaceClosure on a HeapRegion.
2630 
2631 class SpaceClosureRegionClosure: public HeapRegionClosure {
2632   SpaceClosure* _cl;
2633 public:
2634   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2635   bool doHeapRegion(HeapRegion* r) {
2636     _cl->do_space(r);
2637     return false;
2638   }
2639 };
2640 
2641 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2642   SpaceClosureRegionClosure blk(cl);
2643   heap_region_iterate(&blk);
2644 }
2645 
2646 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2647   _hrs.iterate(cl);
2648 }
2649 
2650 void
2651 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2652                                                  uint worker_id,
2653                                                  uint no_of_par_workers,
2654                                                  jint claim_value) {
2655   const uint regions = n_regions();
2656   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2657                              no_of_par_workers :
2658                              1);
2659   assert(UseDynamicNumberOfGCThreads ||
2660          no_of_par_workers == workers()->total_workers(),
2661          "Non dynamic should use fixed number of workers");
2662   // try to spread out the starting points of the workers
2663   const HeapRegion* start_hr =
2664                         start_region_for_worker(worker_id, no_of_par_workers);
2665   const uint start_index = start_hr->hrs_index();
2666 
2667   // each worker will actually look at all regions
2668   for (uint count = 0; count < regions; ++count) {
2669     const uint index = (start_index + count) % regions;
2670     assert(0 <= index && index < regions, "sanity");
2671     HeapRegion* r = region_at(index);
2672     // we'll ignore "continues humongous" regions (we'll process them
2673     // when we come across their corresponding "start humongous"
2674     // region) and regions already claimed
2675     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2676       continue;
2677     }
2678     // OK, try to claim it
2679     if (r->claimHeapRegion(claim_value)) {
2680       // success!
2681       assert(!r->continuesHumongous(), "sanity");
2682       if (r->startsHumongous()) {
2683         // If the region is "starts humongous" we'll iterate over its
2684         // "continues humongous" first; in fact we'll do them
2685         // first. The order is important. In on case, calling the
2686         // closure on the "starts humongous" region might de-allocate
2687         // and clear all its "continues humongous" regions and, as a
2688         // result, we might end up processing them twice. So, we'll do
2689         // them first (notice: most closures will ignore them anyway) and
2690         // then we'll do the "starts humongous" region.
2691         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2692           HeapRegion* chr = region_at(ch_index);
2693 
2694           // if the region has already been claimed or it's not
2695           // "continues humongous" we're done
2696           if (chr->claim_value() == claim_value ||
2697               !chr->continuesHumongous()) {
2698             break;
2699           }
2700 
2701           // No one should have claimed it directly. We can given
2702           // that we claimed its "starts humongous" region.
2703           assert(chr->claim_value() != claim_value, "sanity");
2704           assert(chr->humongous_start_region() == r, "sanity");
2705 
2706           if (chr->claimHeapRegion(claim_value)) {
2707             // we should always be able to claim it; no one else should
2708             // be trying to claim this region
2709 
2710             bool res2 = cl->doHeapRegion(chr);
2711             assert(!res2, "Should not abort");
2712 
2713             // Right now, this holds (i.e., no closure that actually
2714             // does something with "continues humongous" regions
2715             // clears them). We might have to weaken it in the future,
2716             // but let's leave these two asserts here for extra safety.
2717             assert(chr->continuesHumongous(), "should still be the case");
2718             assert(chr->humongous_start_region() == r, "sanity");
2719           } else {
2720             guarantee(false, "we should not reach here");
2721           }
2722         }
2723       }
2724 
2725       assert(!r->continuesHumongous(), "sanity");
2726       bool res = cl->doHeapRegion(r);
2727       assert(!res, "Should not abort");
2728     }
2729   }
2730 }
2731 
2732 class ResetClaimValuesClosure: public HeapRegionClosure {
2733 public:
2734   bool doHeapRegion(HeapRegion* r) {
2735     r->set_claim_value(HeapRegion::InitialClaimValue);
2736     return false;
2737   }
2738 };
2739 
2740 void G1CollectedHeap::reset_heap_region_claim_values() {
2741   ResetClaimValuesClosure blk;
2742   heap_region_iterate(&blk);
2743 }
2744 
2745 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2746   ResetClaimValuesClosure blk;
2747   collection_set_iterate(&blk);
2748 }
2749 
2750 #ifdef ASSERT
2751 // This checks whether all regions in the heap have the correct claim
2752 // value. I also piggy-backed on this a check to ensure that the
2753 // humongous_start_region() information on "continues humongous"
2754 // regions is correct.
2755 
2756 class CheckClaimValuesClosure : public HeapRegionClosure {
2757 private:
2758   jint _claim_value;
2759   uint _failures;
2760   HeapRegion* _sh_region;
2761 
2762 public:
2763   CheckClaimValuesClosure(jint claim_value) :
2764     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2765   bool doHeapRegion(HeapRegion* r) {
2766     if (r->claim_value() != _claim_value) {
2767       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2768                              "claim value = %d, should be %d",
2769                              HR_FORMAT_PARAMS(r),
2770                              r->claim_value(), _claim_value);
2771       ++_failures;
2772     }
2773     if (!r->isHumongous()) {
2774       _sh_region = NULL;
2775     } else if (r->startsHumongous()) {
2776       _sh_region = r;
2777     } else if (r->continuesHumongous()) {
2778       if (r->humongous_start_region() != _sh_region) {
2779         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2780                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2781                                HR_FORMAT_PARAMS(r),
2782                                r->humongous_start_region(),
2783                                _sh_region);
2784         ++_failures;
2785       }
2786     }
2787     return false;
2788   }
2789   uint failures() { return _failures; }
2790 };
2791 
2792 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2793   CheckClaimValuesClosure cl(claim_value);
2794   heap_region_iterate(&cl);
2795   return cl.failures() == 0;
2796 }
2797 
2798 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2799 private:
2800   jint _claim_value;
2801   uint _failures;
2802 
2803 public:
2804   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2805     _claim_value(claim_value), _failures(0) { }
2806 
2807   uint failures() { return _failures; }
2808 
2809   bool doHeapRegion(HeapRegion* hr) {
2810     assert(hr->in_collection_set(), "how?");
2811     assert(!hr->isHumongous(), "H-region in CSet");
2812     if (hr->claim_value() != _claim_value) {
2813       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2814                              "claim value = %d, should be %d",
2815                              HR_FORMAT_PARAMS(hr),
2816                              hr->claim_value(), _claim_value);
2817       _failures += 1;
2818     }
2819     return false;
2820   }
2821 };
2822 
2823 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2824   CheckClaimValuesInCSetHRClosure cl(claim_value);
2825   collection_set_iterate(&cl);
2826   return cl.failures() == 0;
2827 }
2828 #endif // ASSERT
2829 
2830 // Clear the cached CSet starting regions and (more importantly)
2831 // the time stamps. Called when we reset the GC time stamp.
2832 void G1CollectedHeap::clear_cset_start_regions() {
2833   assert(_worker_cset_start_region != NULL, "sanity");
2834   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2835 
2836   int n_queues = MAX2((int)ParallelGCThreads, 1);
2837   for (int i = 0; i < n_queues; i++) {
2838     _worker_cset_start_region[i] = NULL;
2839     _worker_cset_start_region_time_stamp[i] = 0;
2840   }
2841 }
2842 
2843 // Given the id of a worker, obtain or calculate a suitable
2844 // starting region for iterating over the current collection set.
2845 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2846   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2847 
2848   HeapRegion* result = NULL;
2849   unsigned gc_time_stamp = get_gc_time_stamp();
2850 
2851   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2852     // Cached starting region for current worker was set
2853     // during the current pause - so it's valid.
2854     // Note: the cached starting heap region may be NULL
2855     // (when the collection set is empty).
2856     result = _worker_cset_start_region[worker_i];
2857     assert(result == NULL || result->in_collection_set(), "sanity");
2858     return result;
2859   }
2860 
2861   // The cached entry was not valid so let's calculate
2862   // a suitable starting heap region for this worker.
2863 
2864   // We want the parallel threads to start their collection
2865   // set iteration at different collection set regions to
2866   // avoid contention.
2867   // If we have:
2868   //          n collection set regions
2869   //          p threads
2870   // Then thread t will start at region floor ((t * n) / p)
2871 
2872   result = g1_policy()->collection_set();
2873   if (G1CollectedHeap::use_parallel_gc_threads()) {
2874     uint cs_size = g1_policy()->cset_region_length();
2875     uint active_workers = workers()->active_workers();
2876     assert(UseDynamicNumberOfGCThreads ||
2877              active_workers == workers()->total_workers(),
2878              "Unless dynamic should use total workers");
2879 
2880     uint end_ind   = (cs_size * worker_i) / active_workers;
2881     uint start_ind = 0;
2882 
2883     if (worker_i > 0 &&
2884         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2885       // Previous workers starting region is valid
2886       // so let's iterate from there
2887       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2888       result = _worker_cset_start_region[worker_i - 1];
2889     }
2890 
2891     for (uint i = start_ind; i < end_ind; i++) {
2892       result = result->next_in_collection_set();
2893     }
2894   }
2895 
2896   // Note: the calculated starting heap region may be NULL
2897   // (when the collection set is empty).
2898   assert(result == NULL || result->in_collection_set(), "sanity");
2899   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2900          "should be updated only once per pause");
2901   _worker_cset_start_region[worker_i] = result;
2902   OrderAccess::storestore();
2903   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2904   return result;
2905 }
2906 
2907 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2908                                                      uint no_of_par_workers) {
2909   uint worker_num =
2910            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2911   assert(UseDynamicNumberOfGCThreads ||
2912          no_of_par_workers == workers()->total_workers(),
2913          "Non dynamic should use fixed number of workers");
2914   const uint start_index = n_regions() * worker_i / worker_num;
2915   return region_at(start_index);
2916 }
2917 
2918 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2919   HeapRegion* r = g1_policy()->collection_set();
2920   while (r != NULL) {
2921     HeapRegion* next = r->next_in_collection_set();
2922     if (cl->doHeapRegion(r)) {
2923       cl->incomplete();
2924       return;
2925     }
2926     r = next;
2927   }
2928 }
2929 
2930 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2931                                                   HeapRegionClosure *cl) {
2932   if (r == NULL) {
2933     // The CSet is empty so there's nothing to do.
2934     return;
2935   }
2936 
2937   assert(r->in_collection_set(),
2938          "Start region must be a member of the collection set.");
2939   HeapRegion* cur = r;
2940   while (cur != NULL) {
2941     HeapRegion* next = cur->next_in_collection_set();
2942     if (cl->doHeapRegion(cur) && false) {
2943       cl->incomplete();
2944       return;
2945     }
2946     cur = next;
2947   }
2948   cur = g1_policy()->collection_set();
2949   while (cur != r) {
2950     HeapRegion* next = cur->next_in_collection_set();
2951     if (cl->doHeapRegion(cur) && false) {
2952       cl->incomplete();
2953       return;
2954     }
2955     cur = next;
2956   }
2957 }
2958 
2959 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2960   return n_regions() > 0 ? region_at(0) : NULL;
2961 }
2962 
2963 
2964 Space* G1CollectedHeap::space_containing(const void* addr) const {
2965   Space* res = heap_region_containing(addr);
2966   return res;
2967 }
2968 
2969 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2970   Space* sp = space_containing(addr);
2971   if (sp != NULL) {
2972     return sp->block_start(addr);
2973   }
2974   return NULL;
2975 }
2976 
2977 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2978   Space* sp = space_containing(addr);
2979   assert(sp != NULL, "block_size of address outside of heap");
2980   return sp->block_size(addr);
2981 }
2982 
2983 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2984   Space* sp = space_containing(addr);
2985   return sp->block_is_obj(addr);
2986 }
2987 
2988 bool G1CollectedHeap::supports_tlab_allocation() const {
2989   return true;
2990 }
2991 
2992 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2993   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2994 }
2995 
2996 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2997   return young_list()->eden_used_bytes();
2998 }
2999 
3000 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3001 // must be smaller than the humongous object limit.
3002 size_t G1CollectedHeap::max_tlab_size() const {
3003   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3004 }
3005 
3006 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3007   // Return the remaining space in the cur alloc region, but not less than
3008   // the min TLAB size.
3009 
3010   // Also, this value can be at most the humongous object threshold,
3011   // since we can't allow tlabs to grow big enough to accommodate
3012   // humongous objects.
3013 
3014   HeapRegion* hr = _mutator_alloc_region.get();
3015   size_t max_tlab = max_tlab_size() * wordSize;
3016   if (hr == NULL) {
3017     return max_tlab;
3018   } else {
3019     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3020   }
3021 }
3022 
3023 size_t G1CollectedHeap::max_capacity() const {
3024   return _g1_reserved.byte_size();
3025 }
3026 
3027 jlong G1CollectedHeap::millis_since_last_gc() {
3028   // assert(false, "NYI");
3029   return 0;
3030 }
3031 
3032 void G1CollectedHeap::prepare_for_verify() {
3033   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3034     ensure_parsability(false);
3035   }
3036   g1_rem_set()->prepare_for_verify();
3037 }
3038 
3039 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3040                                               VerifyOption vo) {
3041   switch (vo) {
3042   case VerifyOption_G1UsePrevMarking:
3043     return hr->obj_allocated_since_prev_marking(obj);
3044   case VerifyOption_G1UseNextMarking:
3045     return hr->obj_allocated_since_next_marking(obj);
3046   case VerifyOption_G1UseMarkWord:
3047     return false;
3048   default:
3049     ShouldNotReachHere();
3050   }
3051   return false; // keep some compilers happy
3052 }
3053 
3054 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3055   switch (vo) {
3056   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3057   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3058   case VerifyOption_G1UseMarkWord:    return NULL;
3059   default:                            ShouldNotReachHere();
3060   }
3061   return NULL; // keep some compilers happy
3062 }
3063 
3064 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3065   switch (vo) {
3066   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3067   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3068   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3069   default:                            ShouldNotReachHere();
3070   }
3071   return false; // keep some compilers happy
3072 }
3073 
3074 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3075   switch (vo) {
3076   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3077   case VerifyOption_G1UseNextMarking: return "NTAMS";
3078   case VerifyOption_G1UseMarkWord:    return "NONE";
3079   default:                            ShouldNotReachHere();
3080   }
3081   return NULL; // keep some compilers happy
3082 }
3083 
3084 class VerifyRootsClosure: public OopClosure {
3085 private:
3086   G1CollectedHeap* _g1h;
3087   VerifyOption     _vo;
3088   bool             _failures;
3089 public:
3090   // _vo == UsePrevMarking -> use "prev" marking information,
3091   // _vo == UseNextMarking -> use "next" marking information,
3092   // _vo == UseMarkWord    -> use mark word from object header.
3093   VerifyRootsClosure(VerifyOption vo) :
3094     _g1h(G1CollectedHeap::heap()),
3095     _vo(vo),
3096     _failures(false) { }
3097 
3098   bool failures() { return _failures; }
3099 
3100   template <class T> void do_oop_nv(T* p) {
3101     T heap_oop = oopDesc::load_heap_oop(p);
3102     if (!oopDesc::is_null(heap_oop)) {
3103       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3104       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3105         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3106                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3107         if (_vo == VerifyOption_G1UseMarkWord) {
3108           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3109         }
3110         obj->print_on(gclog_or_tty);
3111         _failures = true;
3112       }
3113     }
3114   }
3115 
3116   void do_oop(oop* p)       { do_oop_nv(p); }
3117   void do_oop(narrowOop* p) { do_oop_nv(p); }
3118 };
3119 
3120 class G1VerifyCodeRootOopClosure: public OopClosure {
3121   G1CollectedHeap* _g1h;
3122   OopClosure* _root_cl;
3123   nmethod* _nm;
3124   VerifyOption _vo;
3125   bool _failures;
3126 
3127   template <class T> void do_oop_work(T* p) {
3128     // First verify that this root is live
3129     _root_cl->do_oop(p);
3130 
3131     if (!G1VerifyHeapRegionCodeRoots) {
3132       // We're not verifying the code roots attached to heap region.
3133       return;
3134     }
3135 
3136     // Don't check the code roots during marking verification in a full GC
3137     if (_vo == VerifyOption_G1UseMarkWord) {
3138       return;
3139     }
3140 
3141     // Now verify that the current nmethod (which contains p) is
3142     // in the code root list of the heap region containing the
3143     // object referenced by p.
3144 
3145     T heap_oop = oopDesc::load_heap_oop(p);
3146     if (!oopDesc::is_null(heap_oop)) {
3147       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3148 
3149       // Now fetch the region containing the object
3150       HeapRegion* hr = _g1h->heap_region_containing(obj);
3151       HeapRegionRemSet* hrrs = hr->rem_set();
3152       // Verify that the strong code root list for this region
3153       // contains the nmethod
3154       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3155         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3156                               "from nmethod "PTR_FORMAT" not in strong "
3157                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3158                               p, _nm, hr->bottom(), hr->end());
3159         _failures = true;
3160       }
3161     }
3162   }
3163 
3164 public:
3165   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3166     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3167 
3168   void do_oop(oop* p) { do_oop_work(p); }
3169   void do_oop(narrowOop* p) { do_oop_work(p); }
3170 
3171   void set_nmethod(nmethod* nm) { _nm = nm; }
3172   bool failures() { return _failures; }
3173 };
3174 
3175 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3176   G1VerifyCodeRootOopClosure* _oop_cl;
3177 
3178 public:
3179   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3180     _oop_cl(oop_cl) {}
3181 
3182   void do_code_blob(CodeBlob* cb) {
3183     nmethod* nm = cb->as_nmethod_or_null();
3184     if (nm != NULL) {
3185       _oop_cl->set_nmethod(nm);
3186       nm->oops_do(_oop_cl);
3187     }
3188   }
3189 };
3190 
3191 class YoungRefCounterClosure : public OopClosure {
3192   G1CollectedHeap* _g1h;
3193   int              _count;
3194  public:
3195   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3196   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3197   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3198 
3199   int count() { return _count; }
3200   void reset_count() { _count = 0; };
3201 };
3202 
3203 class VerifyKlassClosure: public KlassClosure {
3204   YoungRefCounterClosure _young_ref_counter_closure;
3205   OopClosure *_oop_closure;
3206  public:
3207   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3208   void do_klass(Klass* k) {
3209     k->oops_do(_oop_closure);
3210 
3211     _young_ref_counter_closure.reset_count();
3212     k->oops_do(&_young_ref_counter_closure);
3213     if (_young_ref_counter_closure.count() > 0) {
3214       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3215     }
3216   }
3217 };
3218 
3219 class VerifyLivenessOopClosure: public OopClosure {
3220   G1CollectedHeap* _g1h;
3221   VerifyOption _vo;
3222 public:
3223   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3224     _g1h(g1h), _vo(vo)
3225   { }
3226   void do_oop(narrowOop *p) { do_oop_work(p); }
3227   void do_oop(      oop *p) { do_oop_work(p); }
3228 
3229   template <class T> void do_oop_work(T *p) {
3230     oop obj = oopDesc::load_decode_heap_oop(p);
3231     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3232               "Dead object referenced by a not dead object");
3233   }
3234 };
3235 
3236 class VerifyObjsInRegionClosure: public ObjectClosure {
3237 private:
3238   G1CollectedHeap* _g1h;
3239   size_t _live_bytes;
3240   HeapRegion *_hr;
3241   VerifyOption _vo;
3242 public:
3243   // _vo == UsePrevMarking -> use "prev" marking information,
3244   // _vo == UseNextMarking -> use "next" marking information,
3245   // _vo == UseMarkWord    -> use mark word from object header.
3246   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3247     : _live_bytes(0), _hr(hr), _vo(vo) {
3248     _g1h = G1CollectedHeap::heap();
3249   }
3250   void do_object(oop o) {
3251     VerifyLivenessOopClosure isLive(_g1h, _vo);
3252     assert(o != NULL, "Huh?");
3253     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3254       // If the object is alive according to the mark word,
3255       // then verify that the marking information agrees.
3256       // Note we can't verify the contra-positive of the
3257       // above: if the object is dead (according to the mark
3258       // word), it may not be marked, or may have been marked
3259       // but has since became dead, or may have been allocated
3260       // since the last marking.
3261       if (_vo == VerifyOption_G1UseMarkWord) {
3262         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3263       }
3264 
3265       o->oop_iterate_no_header(&isLive);
3266       if (!_hr->obj_allocated_since_prev_marking(o)) {
3267         size_t obj_size = o->size();    // Make sure we don't overflow
3268         _live_bytes += (obj_size * HeapWordSize);
3269       }
3270     }
3271   }
3272   size_t live_bytes() { return _live_bytes; }
3273 };
3274 
3275 class PrintObjsInRegionClosure : public ObjectClosure {
3276   HeapRegion *_hr;
3277   G1CollectedHeap *_g1;
3278 public:
3279   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3280     _g1 = G1CollectedHeap::heap();
3281   };
3282 
3283   void do_object(oop o) {
3284     if (o != NULL) {
3285       HeapWord *start = (HeapWord *) o;
3286       size_t word_sz = o->size();
3287       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3288                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3289                           (void*) o, word_sz,
3290                           _g1->isMarkedPrev(o),
3291                           _g1->isMarkedNext(o),
3292                           _hr->obj_allocated_since_prev_marking(o));
3293       HeapWord *end = start + word_sz;
3294       HeapWord *cur;
3295       int *val;
3296       for (cur = start; cur < end; cur++) {
3297         val = (int *) cur;
3298         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3299       }
3300     }
3301   }
3302 };
3303 
3304 class VerifyRegionClosure: public HeapRegionClosure {
3305 private:
3306   bool             _par;
3307   VerifyOption     _vo;
3308   bool             _failures;
3309 public:
3310   // _vo == UsePrevMarking -> use "prev" marking information,
3311   // _vo == UseNextMarking -> use "next" marking information,
3312   // _vo == UseMarkWord    -> use mark word from object header.
3313   VerifyRegionClosure(bool par, VerifyOption vo)
3314     : _par(par),
3315       _vo(vo),
3316       _failures(false) {}
3317 
3318   bool failures() {
3319     return _failures;
3320   }
3321 
3322   bool doHeapRegion(HeapRegion* r) {
3323     if (!r->continuesHumongous()) {
3324       bool failures = false;
3325       r->verify(_vo, &failures);
3326       if (failures) {
3327         _failures = true;
3328       } else {
3329         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3330         r->object_iterate(&not_dead_yet_cl);
3331         if (_vo != VerifyOption_G1UseNextMarking) {
3332           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3333             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3334                                    "max_live_bytes "SIZE_FORMAT" "
3335                                    "< calculated "SIZE_FORMAT,
3336                                    r->bottom(), r->end(),
3337                                    r->max_live_bytes(),
3338                                  not_dead_yet_cl.live_bytes());
3339             _failures = true;
3340           }
3341         } else {
3342           // When vo == UseNextMarking we cannot currently do a sanity
3343           // check on the live bytes as the calculation has not been
3344           // finalized yet.
3345         }
3346       }
3347     }
3348     return false; // stop the region iteration if we hit a failure
3349   }
3350 };
3351 
3352 // This is the task used for parallel verification of the heap regions
3353 
3354 class G1ParVerifyTask: public AbstractGangTask {
3355 private:
3356   G1CollectedHeap* _g1h;
3357   VerifyOption     _vo;
3358   bool             _failures;
3359 
3360 public:
3361   // _vo == UsePrevMarking -> use "prev" marking information,
3362   // _vo == UseNextMarking -> use "next" marking information,
3363   // _vo == UseMarkWord    -> use mark word from object header.
3364   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3365     AbstractGangTask("Parallel verify task"),
3366     _g1h(g1h),
3367     _vo(vo),
3368     _failures(false) { }
3369 
3370   bool failures() {
3371     return _failures;
3372   }
3373 
3374   void work(uint worker_id) {
3375     HandleMark hm;
3376     VerifyRegionClosure blk(true, _vo);
3377     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3378                                           _g1h->workers()->active_workers(),
3379                                           HeapRegion::ParVerifyClaimValue);
3380     if (blk.failures()) {
3381       _failures = true;
3382     }
3383   }
3384 };
3385 
3386 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3387   if (SafepointSynchronize::is_at_safepoint()) {
3388     assert(Thread::current()->is_VM_thread(),
3389            "Expected to be executed serially by the VM thread at this point");
3390 
3391     if (!silent) { gclog_or_tty->print("Roots "); }
3392     VerifyRootsClosure rootsCl(vo);
3393     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3394     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3395     VerifyKlassClosure klassCl(this, &rootsCl);
3396 
3397     // We apply the relevant closures to all the oops in the
3398     // system dictionary, the string table and the code cache.
3399     const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3400 
3401     // Need cleared claim bits for the strong roots processing
3402     ClassLoaderDataGraph::clear_claimed_marks();
3403 
3404     process_strong_roots(true,      // activate StrongRootsScope
3405                          false,     // we set "is scavenging" to false,
3406                                     // so we don't reset the dirty cards.
3407                          ScanningOption(so),  // roots scanning options
3408                          &rootsCl,
3409                          &blobsCl,
3410                          &klassCl
3411                          );
3412 
3413     bool failures = rootsCl.failures() || codeRootsCl.failures();
3414 
3415     if (vo != VerifyOption_G1UseMarkWord) {
3416       // If we're verifying during a full GC then the region sets
3417       // will have been torn down at the start of the GC. Therefore
3418       // verifying the region sets will fail. So we only verify
3419       // the region sets when not in a full GC.
3420       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3421       verify_region_sets();
3422     }
3423 
3424     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3425     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3426       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3427              "sanity check");
3428 
3429       G1ParVerifyTask task(this, vo);
3430       assert(UseDynamicNumberOfGCThreads ||
3431         workers()->active_workers() == workers()->total_workers(),
3432         "If not dynamic should be using all the workers");
3433       int n_workers = workers()->active_workers();
3434       set_par_threads(n_workers);
3435       workers()->run_task(&task);
3436       set_par_threads(0);
3437       if (task.failures()) {
3438         failures = true;
3439       }
3440 
3441       // Checks that the expected amount of parallel work was done.
3442       // The implication is that n_workers is > 0.
3443       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3444              "sanity check");
3445 
3446       reset_heap_region_claim_values();
3447 
3448       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3449              "sanity check");
3450     } else {
3451       VerifyRegionClosure blk(false, vo);
3452       heap_region_iterate(&blk);
3453       if (blk.failures()) {
3454         failures = true;
3455       }
3456     }
3457     if (!silent) gclog_or_tty->print("RemSet ");
3458     rem_set()->verify();
3459 
3460     if (G1StringDedup::is_enabled()) {
3461       if (!silent) gclog_or_tty->print("StrDedup ");
3462       G1StringDedup::verify();
3463     }
3464 
3465     if (failures) {
3466       gclog_or_tty->print_cr("Heap:");
3467       // It helps to have the per-region information in the output to
3468       // help us track down what went wrong. This is why we call
3469       // print_extended_on() instead of print_on().
3470       print_extended_on(gclog_or_tty);
3471       gclog_or_tty->cr();
3472 #ifndef PRODUCT
3473       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3474         concurrent_mark()->print_reachable("at-verification-failure",
3475                                            vo, false /* all */);
3476       }
3477 #endif
3478       gclog_or_tty->flush();
3479     }
3480     guarantee(!failures, "there should not have been any failures");
3481   } else {
3482     if (!silent) {
3483       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3484       if (G1StringDedup::is_enabled()) {
3485         gclog_or_tty->print(", StrDedup");
3486       }
3487       gclog_or_tty->print(") ");
3488     }
3489   }
3490 }
3491 
3492 void G1CollectedHeap::verify(bool silent) {
3493   verify(silent, VerifyOption_G1UsePrevMarking);
3494 }
3495 
3496 double G1CollectedHeap::verify(bool guard, const char* msg) {
3497   double verify_time_ms = 0.0;
3498 
3499   if (guard && total_collections() >= VerifyGCStartAt) {
3500     double verify_start = os::elapsedTime();
3501     HandleMark hm;  // Discard invalid handles created during verification
3502     prepare_for_verify();
3503     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3504     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3505   }
3506 
3507   return verify_time_ms;
3508 }
3509 
3510 void G1CollectedHeap::verify_before_gc() {
3511   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3512   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3513 }
3514 
3515 void G1CollectedHeap::verify_after_gc() {
3516   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3517   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3518 }
3519 
3520 class PrintRegionClosure: public HeapRegionClosure {
3521   outputStream* _st;
3522 public:
3523   PrintRegionClosure(outputStream* st) : _st(st) {}
3524   bool doHeapRegion(HeapRegion* r) {
3525     r->print_on(_st);
3526     return false;
3527   }
3528 };
3529 
3530 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3531                                        const HeapRegion* hr,
3532                                        const VerifyOption vo) const {
3533   switch (vo) {
3534   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3535   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3536   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3537   default:                            ShouldNotReachHere();
3538   }
3539   return false; // keep some compilers happy
3540 }
3541 
3542 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3543                                        const VerifyOption vo) const {
3544   switch (vo) {
3545   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3546   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3547   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3548   default:                            ShouldNotReachHere();
3549   }
3550   return false; // keep some compilers happy
3551 }
3552 
3553 void G1CollectedHeap::print_on(outputStream* st) const {
3554   st->print(" %-20s", "garbage-first heap");
3555   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3556             capacity()/K, used_unlocked()/K);
3557   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3558             _g1_storage.low_boundary(),
3559             _g1_storage.high(),
3560             _g1_storage.high_boundary());
3561   st->cr();
3562   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3563   uint young_regions = _young_list->length();
3564   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3565             (size_t) young_regions * HeapRegion::GrainBytes / K);
3566   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3567   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3568             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3569   st->cr();
3570   MetaspaceAux::print_on(st);
3571 }
3572 
3573 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3574   print_on(st);
3575 
3576   // Print the per-region information.
3577   st->cr();
3578   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3579                "HS=humongous(starts), HC=humongous(continues), "
3580                "CS=collection set, F=free, TS=gc time stamp, "
3581                "PTAMS=previous top-at-mark-start, "
3582                "NTAMS=next top-at-mark-start)");
3583   PrintRegionClosure blk(st);
3584   heap_region_iterate(&blk);
3585 }
3586 
3587 void G1CollectedHeap::print_on_error(outputStream* st) const {
3588   this->CollectedHeap::print_on_error(st);
3589 
3590   if (_cm != NULL) {
3591     st->cr();
3592     _cm->print_on_error(st);
3593   }
3594 }
3595 
3596 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3597   if (G1CollectedHeap::use_parallel_gc_threads()) {
3598     workers()->print_worker_threads_on(st);
3599   }
3600   _cmThread->print_on(st);
3601   st->cr();
3602   _cm->print_worker_threads_on(st);
3603   _cg1r->print_worker_threads_on(st);
3604   if (G1StringDedup::is_enabled()) {
3605     G1StringDedup::print_worker_threads_on(st);
3606   }
3607 }
3608 
3609 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3610   if (G1CollectedHeap::use_parallel_gc_threads()) {
3611     workers()->threads_do(tc);
3612   }
3613   tc->do_thread(_cmThread);
3614   _cg1r->threads_do(tc);
3615   if (G1StringDedup::is_enabled()) {
3616     G1StringDedup::threads_do(tc);
3617   }
3618 }
3619 
3620 void G1CollectedHeap::print_tracing_info() const {
3621   // We'll overload this to mean "trace GC pause statistics."
3622   if (TraceGen0Time || TraceGen1Time) {
3623     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3624     // to that.
3625     g1_policy()->print_tracing_info();
3626   }
3627   if (G1SummarizeRSetStats) {
3628     g1_rem_set()->print_summary_info();
3629   }
3630   if (G1SummarizeConcMark) {
3631     concurrent_mark()->print_summary_info();
3632   }
3633   g1_policy()->print_yg_surv_rate_info();
3634   SpecializationStats::print();
3635 }
3636 
3637 #ifndef PRODUCT
3638 // Helpful for debugging RSet issues.
3639 
3640 class PrintRSetsClosure : public HeapRegionClosure {
3641 private:
3642   const char* _msg;
3643   size_t _occupied_sum;
3644 
3645 public:
3646   bool doHeapRegion(HeapRegion* r) {
3647     HeapRegionRemSet* hrrs = r->rem_set();
3648     size_t occupied = hrrs->occupied();
3649     _occupied_sum += occupied;
3650 
3651     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3652                            HR_FORMAT_PARAMS(r));
3653     if (occupied == 0) {
3654       gclog_or_tty->print_cr("  RSet is empty");
3655     } else {
3656       hrrs->print();
3657     }
3658     gclog_or_tty->print_cr("----------");
3659     return false;
3660   }
3661 
3662   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3663     gclog_or_tty->cr();
3664     gclog_or_tty->print_cr("========================================");
3665     gclog_or_tty->print_cr("%s", msg);
3666     gclog_or_tty->cr();
3667   }
3668 
3669   ~PrintRSetsClosure() {
3670     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3671     gclog_or_tty->print_cr("========================================");
3672     gclog_or_tty->cr();
3673   }
3674 };
3675 
3676 void G1CollectedHeap::print_cset_rsets() {
3677   PrintRSetsClosure cl("Printing CSet RSets");
3678   collection_set_iterate(&cl);
3679 }
3680 
3681 void G1CollectedHeap::print_all_rsets() {
3682   PrintRSetsClosure cl("Printing All RSets");;
3683   heap_region_iterate(&cl);
3684 }
3685 #endif // PRODUCT
3686 
3687 G1CollectedHeap* G1CollectedHeap::heap() {
3688   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3689          "not a garbage-first heap");
3690   return _g1h;
3691 }
3692 
3693 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3694   // always_do_update_barrier = false;
3695   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3696   // Fill TLAB's and such
3697   accumulate_statistics_all_tlabs();
3698   ensure_parsability(true);
3699 
3700   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3701       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3702     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3703   }
3704 }
3705 
3706 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3707 
3708   if (G1SummarizeRSetStats &&
3709       (G1SummarizeRSetStatsPeriod > 0) &&
3710       // we are at the end of the GC. Total collections has already been increased.
3711       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3712     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3713   }
3714 
3715   // FIXME: what is this about?
3716   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3717   // is set.
3718   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3719                         "derived pointer present"));
3720   // always_do_update_barrier = true;
3721 
3722   resize_all_tlabs();
3723 
3724   // We have just completed a GC. Update the soft reference
3725   // policy with the new heap occupancy
3726   Universe::update_heap_info_at_gc();
3727 }
3728 
3729 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3730                                                unsigned int gc_count_before,
3731                                                bool* succeeded,
3732                                                GCCause::Cause gc_cause) {
3733   assert_heap_not_locked_and_not_at_safepoint();
3734   g1_policy()->record_stop_world_start();
3735   VM_G1IncCollectionPause op(gc_count_before,
3736                              word_size,
3737                              false, /* should_initiate_conc_mark */
3738                              g1_policy()->max_pause_time_ms(),
3739                              gc_cause);
3740   VMThread::execute(&op);
3741 
3742   HeapWord* result = op.result();
3743   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3744   assert(result == NULL || ret_succeeded,
3745          "the result should be NULL if the VM did not succeed");
3746   *succeeded = ret_succeeded;
3747 
3748   assert_heap_not_locked();
3749   return result;
3750 }
3751 
3752 void
3753 G1CollectedHeap::doConcurrentMark() {
3754   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3755   if (!_cmThread->in_progress()) {
3756     _cmThread->set_started();
3757     CGC_lock->notify();
3758   }
3759 }
3760 
3761 size_t G1CollectedHeap::pending_card_num() {
3762   size_t extra_cards = 0;
3763   JavaThread *curr = Threads::first();
3764   while (curr != NULL) {
3765     DirtyCardQueue& dcq = curr->dirty_card_queue();
3766     extra_cards += dcq.size();
3767     curr = curr->next();
3768   }
3769   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3770   size_t buffer_size = dcqs.buffer_size();
3771   size_t buffer_num = dcqs.completed_buffers_num();
3772 
3773   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3774   // in bytes - not the number of 'entries'. We need to convert
3775   // into a number of cards.
3776   return (buffer_size * buffer_num + extra_cards) / oopSize;
3777 }
3778 
3779 size_t G1CollectedHeap::cards_scanned() {
3780   return g1_rem_set()->cardsScanned();
3781 }
3782 
3783 void
3784 G1CollectedHeap::setup_surviving_young_words() {
3785   assert(_surviving_young_words == NULL, "pre-condition");
3786   uint array_length = g1_policy()->young_cset_region_length();
3787   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3788   if (_surviving_young_words == NULL) {
3789     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3790                           "Not enough space for young surv words summary.");
3791   }
3792   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3793 #ifdef ASSERT
3794   for (uint i = 0;  i < array_length; ++i) {
3795     assert( _surviving_young_words[i] == 0, "memset above" );
3796   }
3797 #endif // !ASSERT
3798 }
3799 
3800 void
3801 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3802   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3803   uint array_length = g1_policy()->young_cset_region_length();
3804   for (uint i = 0; i < array_length; ++i) {
3805     _surviving_young_words[i] += surv_young_words[i];
3806   }
3807 }
3808 
3809 void
3810 G1CollectedHeap::cleanup_surviving_young_words() {
3811   guarantee( _surviving_young_words != NULL, "pre-condition" );
3812   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3813   _surviving_young_words = NULL;
3814 }
3815 
3816 #ifdef ASSERT
3817 class VerifyCSetClosure: public HeapRegionClosure {
3818 public:
3819   bool doHeapRegion(HeapRegion* hr) {
3820     // Here we check that the CSet region's RSet is ready for parallel
3821     // iteration. The fields that we'll verify are only manipulated
3822     // when the region is part of a CSet and is collected. Afterwards,
3823     // we reset these fields when we clear the region's RSet (when the
3824     // region is freed) so they are ready when the region is
3825     // re-allocated. The only exception to this is if there's an
3826     // evacuation failure and instead of freeing the region we leave
3827     // it in the heap. In that case, we reset these fields during
3828     // evacuation failure handling.
3829     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3830 
3831     // Here's a good place to add any other checks we'd like to
3832     // perform on CSet regions.
3833     return false;
3834   }
3835 };
3836 #endif // ASSERT
3837 
3838 #if TASKQUEUE_STATS
3839 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3840   st->print_raw_cr("GC Task Stats");
3841   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3842   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3843 }
3844 
3845 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3846   print_taskqueue_stats_hdr(st);
3847 
3848   TaskQueueStats totals;
3849   const int n = workers() != NULL ? workers()->total_workers() : 1;
3850   for (int i = 0; i < n; ++i) {
3851     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3852     totals += task_queue(i)->stats;
3853   }
3854   st->print_raw("tot "); totals.print(st); st->cr();
3855 
3856   DEBUG_ONLY(totals.verify());
3857 }
3858 
3859 void G1CollectedHeap::reset_taskqueue_stats() {
3860   const int n = workers() != NULL ? workers()->total_workers() : 1;
3861   for (int i = 0; i < n; ++i) {
3862     task_queue(i)->stats.reset();
3863   }
3864 }
3865 #endif // TASKQUEUE_STATS
3866 
3867 void G1CollectedHeap::log_gc_header() {
3868   if (!G1Log::fine()) {
3869     return;
3870   }
3871 
3872   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3873 
3874   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3875     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3876     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3877 
3878   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3879 }
3880 
3881 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3882   if (!G1Log::fine()) {
3883     return;
3884   }
3885 
3886   if (G1Log::finer()) {
3887     if (evacuation_failed()) {
3888       gclog_or_tty->print(" (to-space exhausted)");
3889     }
3890     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3891     g1_policy()->phase_times()->note_gc_end();
3892     g1_policy()->phase_times()->print(pause_time_sec);
3893     g1_policy()->print_detailed_heap_transition();
3894   } else {
3895     if (evacuation_failed()) {
3896       gclog_or_tty->print("--");
3897     }
3898     g1_policy()->print_heap_transition();
3899     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3900   }
3901   gclog_or_tty->flush();
3902 }
3903 
3904 bool
3905 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3906   assert_at_safepoint(true /* should_be_vm_thread */);
3907   guarantee(!is_gc_active(), "collection is not reentrant");
3908 
3909   if (GC_locker::check_active_before_gc()) {
3910     return false;
3911   }
3912 
3913   _gc_timer_stw->register_gc_start();
3914 
3915   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3916 
3917   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3918   ResourceMark rm;
3919 
3920   print_heap_before_gc();
3921   trace_heap_before_gc(_gc_tracer_stw);
3922 
3923   verify_region_sets_optional();
3924   verify_dirty_young_regions();
3925 
3926   // This call will decide whether this pause is an initial-mark
3927   // pause. If it is, during_initial_mark_pause() will return true
3928   // for the duration of this pause.
3929   g1_policy()->decide_on_conc_mark_initiation();
3930 
3931   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3932   assert(!g1_policy()->during_initial_mark_pause() ||
3933           g1_policy()->gcs_are_young(), "sanity");
3934 
3935   // We also do not allow mixed GCs during marking.
3936   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3937 
3938   // Record whether this pause is an initial mark. When the current
3939   // thread has completed its logging output and it's safe to signal
3940   // the CM thread, the flag's value in the policy has been reset.
3941   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3942 
3943   // Inner scope for scope based logging, timers, and stats collection
3944   {
3945     EvacuationInfo evacuation_info;
3946 
3947     if (g1_policy()->during_initial_mark_pause()) {
3948       // We are about to start a marking cycle, so we increment the
3949       // full collection counter.
3950       increment_old_marking_cycles_started();
3951       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3952     }
3953 
3954     _gc_tracer_stw->report_yc_type(yc_type());
3955 
3956     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3957 
3958     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3959                                 workers()->active_workers() : 1);
3960     double pause_start_sec = os::elapsedTime();
3961     g1_policy()->phase_times()->note_gc_start(active_workers);
3962     log_gc_header();
3963 
3964     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3965     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3966 
3967     // If the secondary_free_list is not empty, append it to the
3968     // free_list. No need to wait for the cleanup operation to finish;
3969     // the region allocation code will check the secondary_free_list
3970     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3971     // set, skip this step so that the region allocation code has to
3972     // get entries from the secondary_free_list.
3973     if (!G1StressConcRegionFreeing) {
3974       append_secondary_free_list_if_not_empty_with_lock();
3975     }
3976 
3977     assert(check_young_list_well_formed(), "young list should be well formed");
3978     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3979            "sanity check");
3980 
3981     // Don't dynamically change the number of GC threads this early.  A value of
3982     // 0 is used to indicate serial work.  When parallel work is done,
3983     // it will be set.
3984 
3985     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3986       IsGCActiveMark x;
3987 
3988       gc_prologue(false);
3989       increment_total_collections(false /* full gc */);
3990       increment_gc_time_stamp();
3991 
3992       verify_before_gc();
3993 
3994       COMPILER2_PRESENT(DerivedPointerTable::clear());
3995 
3996       // Please see comment in g1CollectedHeap.hpp and
3997       // G1CollectedHeap::ref_processing_init() to see how
3998       // reference processing currently works in G1.
3999 
4000       // Enable discovery in the STW reference processor
4001       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4002                                             true /*verify_no_refs*/);
4003 
4004       {
4005         // We want to temporarily turn off discovery by the
4006         // CM ref processor, if necessary, and turn it back on
4007         // on again later if we do. Using a scoped
4008         // NoRefDiscovery object will do this.
4009         NoRefDiscovery no_cm_discovery(ref_processor_cm());
4010 
4011         // Forget the current alloc region (we might even choose it to be part
4012         // of the collection set!).
4013         release_mutator_alloc_region();
4014 
4015         // We should call this after we retire the mutator alloc
4016         // region(s) so that all the ALLOC / RETIRE events are generated
4017         // before the start GC event.
4018         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4019 
4020         // This timing is only used by the ergonomics to handle our pause target.
4021         // It is unclear why this should not include the full pause. We will
4022         // investigate this in CR 7178365.
4023         //
4024         // Preserving the old comment here if that helps the investigation:
4025         //
4026         // The elapsed time induced by the start time below deliberately elides
4027         // the possible verification above.
4028         double sample_start_time_sec = os::elapsedTime();
4029 
4030 #if YOUNG_LIST_VERBOSE
4031         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4032         _young_list->print();
4033         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4034 #endif // YOUNG_LIST_VERBOSE
4035 
4036         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4037 
4038         double scan_wait_start = os::elapsedTime();
4039         // We have to wait until the CM threads finish scanning the
4040         // root regions as it's the only way to ensure that all the
4041         // objects on them have been correctly scanned before we start
4042         // moving them during the GC.
4043         bool waited = _cm->root_regions()->wait_until_scan_finished();
4044         double wait_time_ms = 0.0;
4045         if (waited) {
4046           double scan_wait_end = os::elapsedTime();
4047           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4048         }
4049         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4050 
4051 #if YOUNG_LIST_VERBOSE
4052         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4053         _young_list->print();
4054 #endif // YOUNG_LIST_VERBOSE
4055 
4056         if (g1_policy()->during_initial_mark_pause()) {
4057           concurrent_mark()->checkpointRootsInitialPre();
4058         }
4059 
4060 #if YOUNG_LIST_VERBOSE
4061         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4062         _young_list->print();
4063         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4064 #endif // YOUNG_LIST_VERBOSE
4065 
4066         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4067 
4068         _cm->note_start_of_gc();
4069         // We should not verify the per-thread SATB buffers given that
4070         // we have not filtered them yet (we'll do so during the
4071         // GC). We also call this after finalize_cset() to
4072         // ensure that the CSet has been finalized.
4073         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4074                                  true  /* verify_enqueued_buffers */,
4075                                  false /* verify_thread_buffers */,
4076                                  true  /* verify_fingers */);
4077 
4078         if (_hr_printer.is_active()) {
4079           HeapRegion* hr = g1_policy()->collection_set();
4080           while (hr != NULL) {
4081             G1HRPrinter::RegionType type;
4082             if (!hr->is_young()) {
4083               type = G1HRPrinter::Old;
4084             } else if (hr->is_survivor()) {
4085               type = G1HRPrinter::Survivor;
4086             } else {
4087               type = G1HRPrinter::Eden;
4088             }
4089             _hr_printer.cset(hr);
4090             hr = hr->next_in_collection_set();
4091           }
4092         }
4093 
4094 #ifdef ASSERT
4095         VerifyCSetClosure cl;
4096         collection_set_iterate(&cl);
4097 #endif // ASSERT
4098 
4099         setup_surviving_young_words();
4100 
4101         // Initialize the GC alloc regions.
4102         init_gc_alloc_regions(evacuation_info);
4103 
4104         // Actually do the work...
4105         evacuate_collection_set(evacuation_info);
4106 
4107         // We do this to mainly verify the per-thread SATB buffers
4108         // (which have been filtered by now) since we didn't verify
4109         // them earlier. No point in re-checking the stacks / enqueued
4110         // buffers given that the CSet has not changed since last time
4111         // we checked.
4112         _cm->verify_no_cset_oops(false /* verify_stacks */,
4113                                  false /* verify_enqueued_buffers */,
4114                                  true  /* verify_thread_buffers */,
4115                                  true  /* verify_fingers */);
4116 
4117         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4118         g1_policy()->clear_collection_set();
4119 
4120         cleanup_surviving_young_words();
4121 
4122         // Start a new incremental collection set for the next pause.
4123         g1_policy()->start_incremental_cset_building();
4124 
4125         clear_cset_fast_test();
4126 
4127         _young_list->reset_sampled_info();
4128 
4129         // Don't check the whole heap at this point as the
4130         // GC alloc regions from this pause have been tagged
4131         // as survivors and moved on to the survivor list.
4132         // Survivor regions will fail the !is_young() check.
4133         assert(check_young_list_empty(false /* check_heap */),
4134           "young list should be empty");
4135 
4136 #if YOUNG_LIST_VERBOSE
4137         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4138         _young_list->print();
4139 #endif // YOUNG_LIST_VERBOSE
4140 
4141         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4142                                              _young_list->first_survivor_region(),
4143                                              _young_list->last_survivor_region());
4144 
4145         _young_list->reset_auxilary_lists();
4146 
4147         if (evacuation_failed()) {
4148           _summary_bytes_used = recalculate_used();
4149           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4150           for (uint i = 0; i < n_queues; i++) {
4151             if (_evacuation_failed_info_array[i].has_failed()) {
4152               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4153             }
4154           }
4155         } else {
4156           // The "used" of the the collection set have already been subtracted
4157           // when they were freed.  Add in the bytes evacuated.
4158           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4159         }
4160 
4161         if (g1_policy()->during_initial_mark_pause()) {
4162           // We have to do this before we notify the CM threads that
4163           // they can start working to make sure that all the
4164           // appropriate initialization is done on the CM object.
4165           concurrent_mark()->checkpointRootsInitialPost();
4166           set_marking_started();
4167           // Note that we don't actually trigger the CM thread at
4168           // this point. We do that later when we're sure that
4169           // the current thread has completed its logging output.
4170         }
4171 
4172         allocate_dummy_regions();
4173 
4174 #if YOUNG_LIST_VERBOSE
4175         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4176         _young_list->print();
4177         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4178 #endif // YOUNG_LIST_VERBOSE
4179 
4180         init_mutator_alloc_region();
4181 
4182         {
4183           size_t expand_bytes = g1_policy()->expansion_amount();
4184           if (expand_bytes > 0) {
4185             size_t bytes_before = capacity();
4186             // No need for an ergo verbose message here,
4187             // expansion_amount() does this when it returns a value > 0.
4188             if (!expand(expand_bytes)) {
4189               // We failed to expand the heap so let's verify that
4190               // committed/uncommitted amount match the backing store
4191               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4192               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4193             }
4194           }
4195         }
4196 
4197         // We redo the verification but now wrt to the new CSet which
4198         // has just got initialized after the previous CSet was freed.
4199         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4200                                  true  /* verify_enqueued_buffers */,
4201                                  true  /* verify_thread_buffers */,
4202                                  true  /* verify_fingers */);
4203         _cm->note_end_of_gc();
4204 
4205         // This timing is only used by the ergonomics to handle our pause target.
4206         // It is unclear why this should not include the full pause. We will
4207         // investigate this in CR 7178365.
4208         double sample_end_time_sec = os::elapsedTime();
4209         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4210         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4211 
4212         MemoryService::track_memory_usage();
4213 
4214         // In prepare_for_verify() below we'll need to scan the deferred
4215         // update buffers to bring the RSets up-to-date if
4216         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4217         // the update buffers we'll probably need to scan cards on the
4218         // regions we just allocated to (i.e., the GC alloc
4219         // regions). However, during the last GC we called
4220         // set_saved_mark() on all the GC alloc regions, so card
4221         // scanning might skip the [saved_mark_word()...top()] area of
4222         // those regions (i.e., the area we allocated objects into
4223         // during the last GC). But it shouldn't. Given that
4224         // saved_mark_word() is conditional on whether the GC time stamp
4225         // on the region is current or not, by incrementing the GC time
4226         // stamp here we invalidate all the GC time stamps on all the
4227         // regions and saved_mark_word() will simply return top() for
4228         // all the regions. This is a nicer way of ensuring this rather
4229         // than iterating over the regions and fixing them. In fact, the
4230         // GC time stamp increment here also ensures that
4231         // saved_mark_word() will return top() between pauses, i.e.,
4232         // during concurrent refinement. So we don't need the
4233         // is_gc_active() check to decided which top to use when
4234         // scanning cards (see CR 7039627).
4235         increment_gc_time_stamp();
4236 
4237         verify_after_gc();
4238 
4239         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4240         ref_processor_stw()->verify_no_references_recorded();
4241 
4242         // CM reference discovery will be re-enabled if necessary.
4243       }
4244 
4245       // We should do this after we potentially expand the heap so
4246       // that all the COMMIT events are generated before the end GC
4247       // event, and after we retire the GC alloc regions so that all
4248       // RETIRE events are generated before the end GC event.
4249       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4250 
4251       if (mark_in_progress()) {
4252         concurrent_mark()->update_g1_committed();
4253       }
4254 
4255 #ifdef TRACESPINNING
4256       ParallelTaskTerminator::print_termination_counts();
4257 #endif
4258 
4259       gc_epilogue(false);
4260     }
4261 
4262     // Print the remainder of the GC log output.
4263     log_gc_footer(os::elapsedTime() - pause_start_sec);
4264 
4265     // It is not yet to safe to tell the concurrent mark to
4266     // start as we have some optional output below. We don't want the
4267     // output from the concurrent mark thread interfering with this
4268     // logging output either.
4269 
4270     _hrs.verify_optional();
4271     verify_region_sets_optional();
4272 
4273     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4274     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4275 
4276     print_heap_after_gc();
4277     trace_heap_after_gc(_gc_tracer_stw);
4278 
4279     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4280     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4281     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4282     // before any GC notifications are raised.
4283     g1mm()->update_sizes();
4284 
4285     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4286     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4287     _gc_timer_stw->register_gc_end();
4288     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4289   }
4290   // It should now be safe to tell the concurrent mark thread to start
4291   // without its logging output interfering with the logging output
4292   // that came from the pause.
4293 
4294   if (should_start_conc_mark) {
4295     // CAUTION: after the doConcurrentMark() call below,
4296     // the concurrent marking thread(s) could be running
4297     // concurrently with us. Make sure that anything after
4298     // this point does not assume that we are the only GC thread
4299     // running. Note: of course, the actual marking work will
4300     // not start until the safepoint itself is released in
4301     // SuspendibleThreadSet::desynchronize().
4302     doConcurrentMark();
4303   }
4304 
4305   return true;
4306 }
4307 
4308 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4309 {
4310   size_t gclab_word_size;
4311   switch (purpose) {
4312     case GCAllocForSurvived:
4313       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4314       break;
4315     case GCAllocForTenured:
4316       gclab_word_size = _old_plab_stats.desired_plab_sz();
4317       break;
4318     default:
4319       assert(false, "unknown GCAllocPurpose");
4320       gclab_word_size = _old_plab_stats.desired_plab_sz();
4321       break;
4322   }
4323 
4324   // Prevent humongous PLAB sizes for two reasons:
4325   // * PLABs are allocated using a similar paths as oops, but should
4326   //   never be in a humongous region
4327   // * Allowing humongous PLABs needlessly churns the region free lists
4328   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4329 }
4330 
4331 void G1CollectedHeap::init_mutator_alloc_region() {
4332   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4333   _mutator_alloc_region.init();
4334 }
4335 
4336 void G1CollectedHeap::release_mutator_alloc_region() {
4337   _mutator_alloc_region.release();
4338   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4339 }
4340 
4341 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4342   assert_at_safepoint(true /* should_be_vm_thread */);
4343 
4344   _survivor_gc_alloc_region.init();
4345   _old_gc_alloc_region.init();
4346   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4347   _retained_old_gc_alloc_region = NULL;
4348 
4349   // We will discard the current GC alloc region if:
4350   // a) it's in the collection set (it can happen!),
4351   // b) it's already full (no point in using it),
4352   // c) it's empty (this means that it was emptied during
4353   // a cleanup and it should be on the free list now), or
4354   // d) it's humongous (this means that it was emptied
4355   // during a cleanup and was added to the free list, but
4356   // has been subsequently used to allocate a humongous
4357   // object that may be less than the region size).
4358   if (retained_region != NULL &&
4359       !retained_region->in_collection_set() &&
4360       !(retained_region->top() == retained_region->end()) &&
4361       !retained_region->is_empty() &&
4362       !retained_region->isHumongous()) {
4363     retained_region->set_saved_mark();
4364     // The retained region was added to the old region set when it was
4365     // retired. We have to remove it now, since we don't allow regions
4366     // we allocate to in the region sets. We'll re-add it later, when
4367     // it's retired again.
4368     _old_set.remove(retained_region);
4369     bool during_im = g1_policy()->during_initial_mark_pause();
4370     retained_region->note_start_of_copying(during_im);
4371     _old_gc_alloc_region.set(retained_region);
4372     _hr_printer.reuse(retained_region);
4373     evacuation_info.set_alloc_regions_used_before(retained_region->used());
4374   }
4375 }
4376 
4377 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4378   evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4379                                          _old_gc_alloc_region.count());
4380   _survivor_gc_alloc_region.release();
4381   // If we have an old GC alloc region to release, we'll save it in
4382   // _retained_old_gc_alloc_region. If we don't
4383   // _retained_old_gc_alloc_region will become NULL. This is what we
4384   // want either way so no reason to check explicitly for either
4385   // condition.
4386   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4387 
4388   if (ResizePLAB) {
4389     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4390     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4391   }
4392 }
4393 
4394 void G1CollectedHeap::abandon_gc_alloc_regions() {
4395   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4396   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4397   _retained_old_gc_alloc_region = NULL;
4398 }
4399 
4400 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4401   _drain_in_progress = false;
4402   set_evac_failure_closure(cl);
4403   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4404 }
4405 
4406 void G1CollectedHeap::finalize_for_evac_failure() {
4407   assert(_evac_failure_scan_stack != NULL &&
4408          _evac_failure_scan_stack->length() == 0,
4409          "Postcondition");
4410   assert(!_drain_in_progress, "Postcondition");
4411   delete _evac_failure_scan_stack;
4412   _evac_failure_scan_stack = NULL;
4413 }
4414 
4415 void G1CollectedHeap::remove_self_forwarding_pointers() {
4416   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4417 
4418   double remove_self_forwards_start = os::elapsedTime();
4419 
4420   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4421 
4422   if (G1CollectedHeap::use_parallel_gc_threads()) {
4423     set_par_threads();
4424     workers()->run_task(&rsfp_task);
4425     set_par_threads(0);
4426   } else {
4427     rsfp_task.work(0);
4428   }
4429 
4430   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4431 
4432   // Reset the claim values in the regions in the collection set.
4433   reset_cset_heap_region_claim_values();
4434 
4435   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4436 
4437   // Now restore saved marks, if any.
4438   assert(_objs_with_preserved_marks.size() ==
4439             _preserved_marks_of_objs.size(), "Both or none.");
4440   while (!_objs_with_preserved_marks.is_empty()) {
4441     oop obj = _objs_with_preserved_marks.pop();
4442     markOop m = _preserved_marks_of_objs.pop();
4443     obj->set_mark(m);
4444   }
4445   _objs_with_preserved_marks.clear(true);
4446   _preserved_marks_of_objs.clear(true);
4447 
4448   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4449 }
4450 
4451 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4452   _evac_failure_scan_stack->push(obj);
4453 }
4454 
4455 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4456   assert(_evac_failure_scan_stack != NULL, "precondition");
4457 
4458   while (_evac_failure_scan_stack->length() > 0) {
4459      oop obj = _evac_failure_scan_stack->pop();
4460      _evac_failure_closure->set_region(heap_region_containing(obj));
4461      obj->oop_iterate_backwards(_evac_failure_closure);
4462   }
4463 }
4464 
4465 oop
4466 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4467                                                oop old) {
4468   assert(obj_in_cs(old),
4469          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4470                  (HeapWord*) old));
4471   markOop m = old->mark();
4472   oop forward_ptr = old->forward_to_atomic(old);
4473   if (forward_ptr == NULL) {
4474     // Forward-to-self succeeded.
4475     assert(_par_scan_state != NULL, "par scan state");
4476     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4477     uint queue_num = _par_scan_state->queue_num();
4478 
4479     _evacuation_failed = true;
4480     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4481     if (_evac_failure_closure != cl) {
4482       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4483       assert(!_drain_in_progress,
4484              "Should only be true while someone holds the lock.");
4485       // Set the global evac-failure closure to the current thread's.
4486       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4487       set_evac_failure_closure(cl);
4488       // Now do the common part.
4489       handle_evacuation_failure_common(old, m);
4490       // Reset to NULL.
4491       set_evac_failure_closure(NULL);
4492     } else {
4493       // The lock is already held, and this is recursive.
4494       assert(_drain_in_progress, "This should only be the recursive case.");
4495       handle_evacuation_failure_common(old, m);
4496     }
4497     return old;
4498   } else {
4499     // Forward-to-self failed. Either someone else managed to allocate
4500     // space for this object (old != forward_ptr) or they beat us in
4501     // self-forwarding it (old == forward_ptr).
4502     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4503            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4504                    "should not be in the CSet",
4505                    (HeapWord*) old, (HeapWord*) forward_ptr));
4506     return forward_ptr;
4507   }
4508 }
4509 
4510 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4511   preserve_mark_if_necessary(old, m);
4512 
4513   HeapRegion* r = heap_region_containing(old);
4514   if (!r->evacuation_failed()) {
4515     r->set_evacuation_failed(true);
4516     _hr_printer.evac_failure(r);
4517   }
4518 
4519   push_on_evac_failure_scan_stack(old);
4520 
4521   if (!_drain_in_progress) {
4522     // prevent recursion in copy_to_survivor_space()
4523     _drain_in_progress = true;
4524     drain_evac_failure_scan_stack();
4525     _drain_in_progress = false;
4526   }
4527 }
4528 
4529 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4530   assert(evacuation_failed(), "Oversaving!");
4531   // We want to call the "for_promotion_failure" version only in the
4532   // case of a promotion failure.
4533   if (m->must_be_preserved_for_promotion_failure(obj)) {
4534     _objs_with_preserved_marks.push(obj);
4535     _preserved_marks_of_objs.push(m);
4536   }
4537 }
4538 
4539 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4540                                                   size_t word_size) {
4541   if (purpose == GCAllocForSurvived) {
4542     HeapWord* result = survivor_attempt_allocation(word_size);
4543     if (result != NULL) {
4544       return result;
4545     } else {
4546       // Let's try to allocate in the old gen in case we can fit the
4547       // object there.
4548       return old_attempt_allocation(word_size);
4549     }
4550   } else {
4551     assert(purpose ==  GCAllocForTenured, "sanity");
4552     HeapWord* result = old_attempt_allocation(word_size);
4553     if (result != NULL) {
4554       return result;
4555     } else {
4556       // Let's try to allocate in the survivors in case we can fit the
4557       // object there.
4558       return survivor_attempt_allocation(word_size);
4559     }
4560   }
4561 
4562   ShouldNotReachHere();
4563   // Trying to keep some compilers happy.
4564   return NULL;
4565 }
4566 
4567 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4568   ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4569 
4570 void G1ParCopyHelper::mark_object(oop obj) {
4571 #ifdef ASSERT
4572   HeapRegion* hr = _g1->heap_region_containing(obj);
4573   assert(hr != NULL, "sanity");
4574   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4575 #endif // ASSERT
4576 
4577   // We know that the object is not moving so it's safe to read its size.
4578   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4579 }
4580 
4581 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4582 #ifdef ASSERT
4583   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4584   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4585   assert(from_obj != to_obj, "should not be self-forwarded");
4586 
4587   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4588   assert(from_hr != NULL, "sanity");
4589   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4590 
4591   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4592   assert(to_hr != NULL, "sanity");
4593   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4594 #endif // ASSERT
4595 
4596   // The object might be in the process of being copied by another
4597   // worker so we cannot trust that its to-space image is
4598   // well-formed. So we have to read its size from its from-space
4599   // image which we know should not be changing.
4600   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4601 }
4602 
4603 template <class T>
4604 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4605   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4606     _scanned_klass->record_modified_oops();
4607   }
4608 }
4609 
4610 template <G1Barrier barrier, bool do_mark_object>
4611 template <class T>
4612 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4613   T heap_oop = oopDesc::load_heap_oop(p);
4614 
4615   if (oopDesc::is_null(heap_oop)) {
4616     return;
4617   }
4618 
4619   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4620 
4621   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4622 
4623   if (_g1->in_cset_fast_test(obj)) {
4624     oop forwardee;
4625     if (obj->is_forwarded()) {
4626       forwardee = obj->forwardee();
4627     } else {
4628       forwardee = _par_scan_state->copy_to_survivor_space(obj);
4629     }
4630     assert(forwardee != NULL, "forwardee should not be NULL");
4631     oopDesc::encode_store_heap_oop(p, forwardee);
4632     if (do_mark_object && forwardee != obj) {
4633       // If the object is self-forwarded we don't need to explicitly
4634       // mark it, the evacuation failure protocol will do so.
4635       mark_forwarded_object(obj, forwardee);
4636     }
4637 
4638     if (barrier == G1BarrierKlass) {
4639       do_klass_barrier(p, forwardee);
4640     }
4641   } else {
4642     // The object is not in collection set. If we're a root scanning
4643     // closure during an initial mark pause (i.e. do_mark_object will
4644     // be true) then attempt to mark the object.
4645     if (do_mark_object) {
4646       mark_object(obj);
4647     }
4648   }
4649 
4650   if (barrier == G1BarrierEvac) {
4651     _par_scan_state->update_rs(_from, p, _worker_id);
4652   }
4653 }
4654 
4655 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4656 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4657 
4658 class G1ParEvacuateFollowersClosure : public VoidClosure {
4659 protected:
4660   G1CollectedHeap*              _g1h;
4661   G1ParScanThreadState*         _par_scan_state;
4662   RefToScanQueueSet*            _queues;
4663   ParallelTaskTerminator*       _terminator;
4664 
4665   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4666   RefToScanQueueSet*      queues()         { return _queues; }
4667   ParallelTaskTerminator* terminator()     { return _terminator; }
4668 
4669 public:
4670   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4671                                 G1ParScanThreadState* par_scan_state,
4672                                 RefToScanQueueSet* queues,
4673                                 ParallelTaskTerminator* terminator)
4674     : _g1h(g1h), _par_scan_state(par_scan_state),
4675       _queues(queues), _terminator(terminator) {}
4676 
4677   void do_void();
4678 
4679 private:
4680   inline bool offer_termination();
4681 };
4682 
4683 bool G1ParEvacuateFollowersClosure::offer_termination() {
4684   G1ParScanThreadState* const pss = par_scan_state();
4685   pss->start_term_time();
4686   const bool res = terminator()->offer_termination();
4687   pss->end_term_time();
4688   return res;
4689 }
4690 
4691 void G1ParEvacuateFollowersClosure::do_void() {
4692   G1ParScanThreadState* const pss = par_scan_state();
4693   pss->trim_queue();
4694   do {
4695     pss->steal_and_trim_queue(queues());
4696   } while (!offer_termination());
4697 }
4698 
4699 class G1KlassScanClosure : public KlassClosure {
4700  G1ParCopyHelper* _closure;
4701  bool             _process_only_dirty;
4702  int              _count;
4703  public:
4704   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4705       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4706   void do_klass(Klass* klass) {
4707     // If the klass has not been dirtied we know that there's
4708     // no references into  the young gen and we can skip it.
4709    if (!_process_only_dirty || klass->has_modified_oops()) {
4710       // Clean the klass since we're going to scavenge all the metadata.
4711       klass->clear_modified_oops();
4712 
4713       // Tell the closure that this klass is the Klass to scavenge
4714       // and is the one to dirty if oops are left pointing into the young gen.
4715       _closure->set_scanned_klass(klass);
4716 
4717       klass->oops_do(_closure);
4718 
4719       _closure->set_scanned_klass(NULL);
4720     }
4721     _count++;
4722   }
4723 };
4724 
4725 class G1ParTask : public AbstractGangTask {
4726 protected:
4727   G1CollectedHeap*       _g1h;
4728   RefToScanQueueSet      *_queues;
4729   ParallelTaskTerminator _terminator;
4730   uint _n_workers;
4731 
4732   Mutex _stats_lock;
4733   Mutex* stats_lock() { return &_stats_lock; }
4734 
4735   size_t getNCards() {
4736     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4737       / G1BlockOffsetSharedArray::N_bytes;
4738   }
4739 
4740 public:
4741   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4742     : AbstractGangTask("G1 collection"),
4743       _g1h(g1h),
4744       _queues(task_queues),
4745       _terminator(0, _queues),
4746       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4747   {}
4748 
4749   RefToScanQueueSet* queues() { return _queues; }
4750 
4751   RefToScanQueue *work_queue(int i) {
4752     return queues()->queue(i);
4753   }
4754 
4755   ParallelTaskTerminator* terminator() { return &_terminator; }
4756 
4757   virtual void set_for_termination(int active_workers) {
4758     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4759     // in the young space (_par_seq_tasks) in the G1 heap
4760     // for SequentialSubTasksDone.
4761     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4762     // both of which need setting by set_n_termination().
4763     _g1h->SharedHeap::set_n_termination(active_workers);
4764     _g1h->set_n_termination(active_workers);
4765     terminator()->reset_for_reuse(active_workers);
4766     _n_workers = active_workers;
4767   }
4768 
4769   void work(uint worker_id) {
4770     if (worker_id >= _n_workers) return;  // no work needed this round
4771 
4772     double start_time_ms = os::elapsedTime() * 1000.0;
4773     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4774 
4775     {
4776       ResourceMark rm;
4777       HandleMark   hm;
4778 
4779       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4780 
4781       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4782       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4783 
4784       pss.set_evac_failure_closure(&evac_failure_cl);
4785 
4786       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4787       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
4788 
4789       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4790       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4791 
4792       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
4793       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4794       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4795 
4796       OopClosure*                    scan_root_cl = &only_scan_root_cl;
4797       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
4798 
4799       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4800         // We also need to mark copied objects.
4801         scan_root_cl = &scan_mark_root_cl;
4802         scan_klasses_cl = &scan_mark_klasses_cl_s;
4803       }
4804 
4805       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
4806 
4807       // Don't scan the scavengable methods in the code cache as part
4808       // of strong root scanning. The code roots that point into a
4809       // region in the collection set are scanned when we scan the
4810       // region's RSet.
4811       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
4812 
4813       pss.start_strong_roots();
4814       _g1h->g1_process_strong_roots(/* is scavenging */ true,
4815                                     SharedHeap::ScanningOption(so),
4816                                     scan_root_cl,
4817                                     &push_heap_rs_cl,
4818                                     scan_klasses_cl,
4819                                     worker_id);
4820       pss.end_strong_roots();
4821 
4822       {
4823         double start = os::elapsedTime();
4824         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4825         evac.do_void();
4826         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4827         double term_ms = pss.term_time()*1000.0;
4828         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4829         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4830       }
4831       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4832       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4833 
4834       if (ParallelGCVerbose) {
4835         MutexLocker x(stats_lock());
4836         pss.print_termination_stats(worker_id);
4837       }
4838 
4839       assert(pss.queue_is_empty(), "should be empty");
4840 
4841       // Close the inner scope so that the ResourceMark and HandleMark
4842       // destructors are executed here and are included as part of the
4843       // "GC Worker Time".
4844     }
4845 
4846     double end_time_ms = os::elapsedTime() * 1000.0;
4847     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4848   }
4849 };
4850 
4851 // *** Common G1 Evacuation Stuff
4852 
4853 // This method is run in a GC worker.
4854 
4855 void
4856 G1CollectedHeap::
4857 g1_process_strong_roots(bool is_scavenging,
4858                         ScanningOption so,
4859                         OopClosure* scan_non_heap_roots,
4860                         OopsInHeapRegionClosure* scan_rs,
4861                         G1KlassScanClosure* scan_klasses,
4862                         uint worker_i) {
4863 
4864   // First scan the strong roots
4865   double ext_roots_start = os::elapsedTime();
4866   double closure_app_time_sec = 0.0;
4867 
4868   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4869 
4870   assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
4871   // Walk the code cache/strong code roots w/o buffering, because StarTask
4872   // cannot handle unaligned oop locations.
4873   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
4874 
4875   process_strong_roots(false, // no scoping; this is parallel code
4876                        is_scavenging, so,
4877                        &buf_scan_non_heap_roots,
4878                        &eager_scan_code_roots,
4879                        scan_klasses
4880                        );
4881 
4882   // Now the CM ref_processor roots.
4883   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4884     // We need to treat the discovered reference lists of the
4885     // concurrent mark ref processor as roots and keep entries
4886     // (which are added by the marking threads) on them live
4887     // until they can be processed at the end of marking.
4888     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4889   }
4890 
4891   // Finish up any enqueued closure apps (attributed as object copy time).
4892   buf_scan_non_heap_roots.done();
4893 
4894   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
4895 
4896   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4897 
4898   double ext_root_time_ms =
4899     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4900 
4901   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4902 
4903   // During conc marking we have to filter the per-thread SATB buffers
4904   // to make sure we remove any oops into the CSet (which will show up
4905   // as implicitly live).
4906   double satb_filtering_ms = 0.0;
4907   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4908     if (mark_in_progress()) {
4909       double satb_filter_start = os::elapsedTime();
4910 
4911       JavaThread::satb_mark_queue_set().filter_thread_buffers();
4912 
4913       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4914     }
4915   }
4916   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4917 
4918   // If this is an initial mark pause, and we're not scanning
4919   // the entire code cache, we need to mark the oops in the
4920   // strong code root lists for the regions that are not in
4921   // the collection set.
4922   // Note all threads participate in this set of root tasks.
4923   double mark_strong_code_roots_ms = 0.0;
4924   if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
4925     double mark_strong_roots_start = os::elapsedTime();
4926     mark_strong_code_roots(worker_i);
4927     mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
4928   }
4929   g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
4930 
4931   // Now scan the complement of the collection set.
4932   if (scan_rs != NULL) {
4933     g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
4934   }
4935   _process_strong_tasks->all_tasks_completed();
4936 }
4937 
4938 void
4939 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
4940   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4941   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
4942 }
4943 
4944 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4945 private:
4946   BoolObjectClosure* _is_alive;
4947   int _initial_string_table_size;
4948   int _initial_symbol_table_size;
4949 
4950   bool  _process_strings;
4951   int _strings_processed;
4952   int _strings_removed;
4953 
4954   bool  _process_symbols;
4955   int _symbols_processed;
4956   int _symbols_removed;
4957 
4958   bool _do_in_parallel;
4959 public:
4960   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4961     AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
4962     _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4963     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4964     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4965 
4966     _initial_string_table_size = StringTable::the_table()->table_size();
4967     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4968     if (process_strings) {
4969       StringTable::clear_parallel_claimed_index();
4970     }
4971     if (process_symbols) {
4972       SymbolTable::clear_parallel_claimed_index();
4973     }
4974   }
4975 
4976   ~G1StringSymbolTableUnlinkTask() {
4977     guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4978               err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4979                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4980     guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4981               err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4982                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4983   }
4984 
4985   void work(uint worker_id) {
4986     if (_do_in_parallel) {
4987       int strings_processed = 0;
4988       int strings_removed = 0;
4989       int symbols_processed = 0;
4990       int symbols_removed = 0;
4991       if (_process_strings) {
4992         StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4993         Atomic::add(strings_processed, &_strings_processed);
4994         Atomic::add(strings_removed, &_strings_removed);
4995       }
4996       if (_process_symbols) {
4997         SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4998         Atomic::add(symbols_processed, &_symbols_processed);
4999         Atomic::add(symbols_removed, &_symbols_removed);
5000       }
5001     } else {
5002       if (_process_strings) {
5003         StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5004       }
5005       if (_process_symbols) {
5006         SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5007       }
5008     }
5009   }
5010 
5011   size_t strings_processed() const { return (size_t)_strings_processed; }
5012   size_t strings_removed()   const { return (size_t)_strings_removed; }
5013 
5014   size_t symbols_processed() const { return (size_t)_symbols_processed; }
5015   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
5016 };
5017 
5018 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5019                                                      bool process_strings, bool process_symbols) {
5020   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5021                    _g1h->workers()->active_workers() : 1);
5022 
5023   G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5024   if (G1CollectedHeap::use_parallel_gc_threads()) {
5025     set_par_threads(n_workers);
5026     workers()->run_task(&g1_unlink_task);
5027     set_par_threads(0);
5028   } else {
5029     g1_unlink_task.work(0);
5030   }
5031   if (G1TraceStringSymbolTableScrubbing) {
5032     gclog_or_tty->print_cr("Cleaned string and symbol table, "
5033                            "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5034                            "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5035                            g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5036                            g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5037   }
5038 
5039   if (G1StringDedup::is_enabled()) {
5040     G1StringDedup::unlink(is_alive);
5041   }
5042 }
5043 
5044 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5045  private:
5046   DirtyCardQueueSet* _queue;
5047  public:
5048   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5049 
5050   virtual void work(uint worker_id) {
5051     double start_time = os::elapsedTime();
5052 
5053     RedirtyLoggedCardTableEntryClosure cl;
5054     if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5055       _queue->par_apply_closure_to_all_completed_buffers(&cl);
5056     } else {
5057       _queue->apply_closure_to_all_completed_buffers(&cl);
5058     }
5059 
5060     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5061     timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5062     timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5063   }
5064 };
5065 
5066 void G1CollectedHeap::redirty_logged_cards() {
5067   guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5068   double redirty_logged_cards_start = os::elapsedTime();
5069 
5070   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5071                    _g1h->workers()->active_workers() : 1);
5072 
5073   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5074   dirty_card_queue_set().reset_for_par_iteration();
5075   if (use_parallel_gc_threads()) {
5076     set_par_threads(n_workers);
5077     workers()->run_task(&redirty_task);
5078     set_par_threads(0);
5079   } else {
5080     redirty_task.work(0);
5081   }
5082 
5083   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5084   dcq.merge_bufferlists(&dirty_card_queue_set());
5085   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5086 
5087   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5088 }
5089 
5090 // Weak Reference Processing support
5091 
5092 // An always "is_alive" closure that is used to preserve referents.
5093 // If the object is non-null then it's alive.  Used in the preservation
5094 // of referent objects that are pointed to by reference objects
5095 // discovered by the CM ref processor.
5096 class G1AlwaysAliveClosure: public BoolObjectClosure {
5097   G1CollectedHeap* _g1;
5098 public:
5099   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5100   bool do_object_b(oop p) {
5101     if (p != NULL) {
5102       return true;
5103     }
5104     return false;
5105   }
5106 };
5107 
5108 bool G1STWIsAliveClosure::do_object_b(oop p) {
5109   // An object is reachable if it is outside the collection set,
5110   // or is inside and copied.
5111   return !_g1->obj_in_cs(p) || p->is_forwarded();
5112 }
5113 
5114 // Non Copying Keep Alive closure
5115 class G1KeepAliveClosure: public OopClosure {
5116   G1CollectedHeap* _g1;
5117 public:
5118   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5119   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5120   void do_oop(      oop* p) {
5121     oop obj = *p;
5122 
5123     if (_g1->obj_in_cs(obj)) {
5124       assert( obj->is_forwarded(), "invariant" );
5125       *p = obj->forwardee();
5126     }
5127   }
5128 };
5129 
5130 // Copying Keep Alive closure - can be called from both
5131 // serial and parallel code as long as different worker
5132 // threads utilize different G1ParScanThreadState instances
5133 // and different queues.
5134 
5135 class G1CopyingKeepAliveClosure: public OopClosure {
5136   G1CollectedHeap*         _g1h;
5137   OopClosure*              _copy_non_heap_obj_cl;
5138   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5139   G1ParScanThreadState*    _par_scan_state;
5140 
5141 public:
5142   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5143                             OopClosure* non_heap_obj_cl,
5144                             OopsInHeapRegionClosure* metadata_obj_cl,
5145                             G1ParScanThreadState* pss):
5146     _g1h(g1h),
5147     _copy_non_heap_obj_cl(non_heap_obj_cl),
5148     _copy_metadata_obj_cl(metadata_obj_cl),
5149     _par_scan_state(pss)
5150   {}
5151 
5152   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5153   virtual void do_oop(      oop* p) { do_oop_work(p); }
5154 
5155   template <class T> void do_oop_work(T* p) {
5156     oop obj = oopDesc::load_decode_heap_oop(p);
5157 
5158     if (_g1h->obj_in_cs(obj)) {
5159       // If the referent object has been forwarded (either copied
5160       // to a new location or to itself in the event of an
5161       // evacuation failure) then we need to update the reference
5162       // field and, if both reference and referent are in the G1
5163       // heap, update the RSet for the referent.
5164       //
5165       // If the referent has not been forwarded then we have to keep
5166       // it alive by policy. Therefore we have copy the referent.
5167       //
5168       // If the reference field is in the G1 heap then we can push
5169       // on the PSS queue. When the queue is drained (after each
5170       // phase of reference processing) the object and it's followers
5171       // will be copied, the reference field set to point to the
5172       // new location, and the RSet updated. Otherwise we need to
5173       // use the the non-heap or metadata closures directly to copy
5174       // the referent object and update the pointer, while avoiding
5175       // updating the RSet.
5176 
5177       if (_g1h->is_in_g1_reserved(p)) {
5178         _par_scan_state->push_on_queue(p);
5179       } else {
5180         assert(!Metaspace::contains((const void*)p),
5181                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5182                               PTR_FORMAT, p));
5183           _copy_non_heap_obj_cl->do_oop(p);
5184         }
5185       }
5186     }
5187 };
5188 
5189 // Serial drain queue closure. Called as the 'complete_gc'
5190 // closure for each discovered list in some of the
5191 // reference processing phases.
5192 
5193 class G1STWDrainQueueClosure: public VoidClosure {
5194 protected:
5195   G1CollectedHeap* _g1h;
5196   G1ParScanThreadState* _par_scan_state;
5197 
5198   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5199 
5200 public:
5201   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5202     _g1h(g1h),
5203     _par_scan_state(pss)
5204   { }
5205 
5206   void do_void() {
5207     G1ParScanThreadState* const pss = par_scan_state();
5208     pss->trim_queue();
5209   }
5210 };
5211 
5212 // Parallel Reference Processing closures
5213 
5214 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5215 // processing during G1 evacuation pauses.
5216 
5217 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5218 private:
5219   G1CollectedHeap*   _g1h;
5220   RefToScanQueueSet* _queues;
5221   FlexibleWorkGang*  _workers;
5222   int                _active_workers;
5223 
5224 public:
5225   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5226                         FlexibleWorkGang* workers,
5227                         RefToScanQueueSet *task_queues,
5228                         int n_workers) :
5229     _g1h(g1h),
5230     _queues(task_queues),
5231     _workers(workers),
5232     _active_workers(n_workers)
5233   {
5234     assert(n_workers > 0, "shouldn't call this otherwise");
5235   }
5236 
5237   // Executes the given task using concurrent marking worker threads.
5238   virtual void execute(ProcessTask& task);
5239   virtual void execute(EnqueueTask& task);
5240 };
5241 
5242 // Gang task for possibly parallel reference processing
5243 
5244 class G1STWRefProcTaskProxy: public AbstractGangTask {
5245   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5246   ProcessTask&     _proc_task;
5247   G1CollectedHeap* _g1h;
5248   RefToScanQueueSet *_task_queues;
5249   ParallelTaskTerminator* _terminator;
5250 
5251 public:
5252   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5253                      G1CollectedHeap* g1h,
5254                      RefToScanQueueSet *task_queues,
5255                      ParallelTaskTerminator* terminator) :
5256     AbstractGangTask("Process reference objects in parallel"),
5257     _proc_task(proc_task),
5258     _g1h(g1h),
5259     _task_queues(task_queues),
5260     _terminator(terminator)
5261   {}
5262 
5263   virtual void work(uint worker_id) {
5264     // The reference processing task executed by a single worker.
5265     ResourceMark rm;
5266     HandleMark   hm;
5267 
5268     G1STWIsAliveClosure is_alive(_g1h);
5269 
5270     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5271     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5272 
5273     pss.set_evac_failure_closure(&evac_failure_cl);
5274 
5275     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5276     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5277 
5278     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5279     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5280 
5281     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5282     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5283 
5284     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5285       // We also need to mark copied objects.
5286       copy_non_heap_cl = &copy_mark_non_heap_cl;
5287       copy_metadata_cl = &copy_mark_metadata_cl;
5288     }
5289 
5290     // Keep alive closure.
5291     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5292 
5293     // Complete GC closure
5294     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5295 
5296     // Call the reference processing task's work routine.
5297     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5298 
5299     // Note we cannot assert that the refs array is empty here as not all
5300     // of the processing tasks (specifically phase2 - pp2_work) execute
5301     // the complete_gc closure (which ordinarily would drain the queue) so
5302     // the queue may not be empty.
5303   }
5304 };
5305 
5306 // Driver routine for parallel reference processing.
5307 // Creates an instance of the ref processing gang
5308 // task and has the worker threads execute it.
5309 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5310   assert(_workers != NULL, "Need parallel worker threads.");
5311 
5312   ParallelTaskTerminator terminator(_active_workers, _queues);
5313   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5314 
5315   _g1h->set_par_threads(_active_workers);
5316   _workers->run_task(&proc_task_proxy);
5317   _g1h->set_par_threads(0);
5318 }
5319 
5320 // Gang task for parallel reference enqueueing.
5321 
5322 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5323   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5324   EnqueueTask& _enq_task;
5325 
5326 public:
5327   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5328     AbstractGangTask("Enqueue reference objects in parallel"),
5329     _enq_task(enq_task)
5330   { }
5331 
5332   virtual void work(uint worker_id) {
5333     _enq_task.work(worker_id);
5334   }
5335 };
5336 
5337 // Driver routine for parallel reference enqueueing.
5338 // Creates an instance of the ref enqueueing gang
5339 // task and has the worker threads execute it.
5340 
5341 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5342   assert(_workers != NULL, "Need parallel worker threads.");
5343 
5344   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5345 
5346   _g1h->set_par_threads(_active_workers);
5347   _workers->run_task(&enq_task_proxy);
5348   _g1h->set_par_threads(0);
5349 }
5350 
5351 // End of weak reference support closures
5352 
5353 // Abstract task used to preserve (i.e. copy) any referent objects
5354 // that are in the collection set and are pointed to by reference
5355 // objects discovered by the CM ref processor.
5356 
5357 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5358 protected:
5359   G1CollectedHeap* _g1h;
5360   RefToScanQueueSet      *_queues;
5361   ParallelTaskTerminator _terminator;
5362   uint _n_workers;
5363 
5364 public:
5365   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5366     AbstractGangTask("ParPreserveCMReferents"),
5367     _g1h(g1h),
5368     _queues(task_queues),
5369     _terminator(workers, _queues),
5370     _n_workers(workers)
5371   { }
5372 
5373   void work(uint worker_id) {
5374     ResourceMark rm;
5375     HandleMark   hm;
5376 
5377     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5378     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5379 
5380     pss.set_evac_failure_closure(&evac_failure_cl);
5381 
5382     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5383 
5384     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5385     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5386 
5387     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5388     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5389 
5390     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5391     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5392 
5393     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5394       // We also need to mark copied objects.
5395       copy_non_heap_cl = &copy_mark_non_heap_cl;
5396       copy_metadata_cl = &copy_mark_metadata_cl;
5397     }
5398 
5399     // Is alive closure
5400     G1AlwaysAliveClosure always_alive(_g1h);
5401 
5402     // Copying keep alive closure. Applied to referent objects that need
5403     // to be copied.
5404     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5405 
5406     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5407 
5408     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5409     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5410 
5411     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5412     // So this must be true - but assert just in case someone decides to
5413     // change the worker ids.
5414     assert(0 <= worker_id && worker_id < limit, "sanity");
5415     assert(!rp->discovery_is_atomic(), "check this code");
5416 
5417     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5418     for (uint idx = worker_id; idx < limit; idx += stride) {
5419       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5420 
5421       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5422       while (iter.has_next()) {
5423         // Since discovery is not atomic for the CM ref processor, we
5424         // can see some null referent objects.
5425         iter.load_ptrs(DEBUG_ONLY(true));
5426         oop ref = iter.obj();
5427 
5428         // This will filter nulls.
5429         if (iter.is_referent_alive()) {
5430           iter.make_referent_alive();
5431         }
5432         iter.move_to_next();
5433       }
5434     }
5435 
5436     // Drain the queue - which may cause stealing
5437     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5438     drain_queue.do_void();
5439     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5440     assert(pss.queue_is_empty(), "should be");
5441   }
5442 };
5443 
5444 // Weak Reference processing during an evacuation pause (part 1).
5445 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5446   double ref_proc_start = os::elapsedTime();
5447 
5448   ReferenceProcessor* rp = _ref_processor_stw;
5449   assert(rp->discovery_enabled(), "should have been enabled");
5450 
5451   // Any reference objects, in the collection set, that were 'discovered'
5452   // by the CM ref processor should have already been copied (either by
5453   // applying the external root copy closure to the discovered lists, or
5454   // by following an RSet entry).
5455   //
5456   // But some of the referents, that are in the collection set, that these
5457   // reference objects point to may not have been copied: the STW ref
5458   // processor would have seen that the reference object had already
5459   // been 'discovered' and would have skipped discovering the reference,
5460   // but would not have treated the reference object as a regular oop.
5461   // As a result the copy closure would not have been applied to the
5462   // referent object.
5463   //
5464   // We need to explicitly copy these referent objects - the references
5465   // will be processed at the end of remarking.
5466   //
5467   // We also need to do this copying before we process the reference
5468   // objects discovered by the STW ref processor in case one of these
5469   // referents points to another object which is also referenced by an
5470   // object discovered by the STW ref processor.
5471 
5472   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5473            no_of_gc_workers == workers()->active_workers(),
5474            "Need to reset active GC workers");
5475 
5476   set_par_threads(no_of_gc_workers);
5477   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5478                                                  no_of_gc_workers,
5479                                                  _task_queues);
5480 
5481   if (G1CollectedHeap::use_parallel_gc_threads()) {
5482     workers()->run_task(&keep_cm_referents);
5483   } else {
5484     keep_cm_referents.work(0);
5485   }
5486 
5487   set_par_threads(0);
5488 
5489   // Closure to test whether a referent is alive.
5490   G1STWIsAliveClosure is_alive(this);
5491 
5492   // Even when parallel reference processing is enabled, the processing
5493   // of JNI refs is serial and performed serially by the current thread
5494   // rather than by a worker. The following PSS will be used for processing
5495   // JNI refs.
5496 
5497   // Use only a single queue for this PSS.
5498   G1ParScanThreadState            pss(this, 0, NULL);
5499 
5500   // We do not embed a reference processor in the copying/scanning
5501   // closures while we're actually processing the discovered
5502   // reference objects.
5503   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5504 
5505   pss.set_evac_failure_closure(&evac_failure_cl);
5506 
5507   assert(pss.queue_is_empty(), "pre-condition");
5508 
5509   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5510   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5511 
5512   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5513   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5514 
5515   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5516   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5517 
5518   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5519     // We also need to mark copied objects.
5520     copy_non_heap_cl = &copy_mark_non_heap_cl;
5521     copy_metadata_cl = &copy_mark_metadata_cl;
5522   }
5523 
5524   // Keep alive closure.
5525   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5526 
5527   // Serial Complete GC closure
5528   G1STWDrainQueueClosure drain_queue(this, &pss);
5529 
5530   // Setup the soft refs policy...
5531   rp->setup_policy(false);
5532 
5533   ReferenceProcessorStats stats;
5534   if (!rp->processing_is_mt()) {
5535     // Serial reference processing...
5536     stats = rp->process_discovered_references(&is_alive,
5537                                               &keep_alive,
5538                                               &drain_queue,
5539                                               NULL,
5540                                               _gc_timer_stw,
5541                                               _gc_tracer_stw->gc_id());
5542   } else {
5543     // Parallel reference processing
5544     assert(rp->num_q() == no_of_gc_workers, "sanity");
5545     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5546 
5547     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5548     stats = rp->process_discovered_references(&is_alive,
5549                                               &keep_alive,
5550                                               &drain_queue,
5551                                               &par_task_executor,
5552                                               _gc_timer_stw,
5553                                               _gc_tracer_stw->gc_id());
5554   }
5555 
5556   _gc_tracer_stw->report_gc_reference_stats(stats);
5557 
5558   // We have completed copying any necessary live referent objects.
5559   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5560 
5561   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5562   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5563 }
5564 
5565 // Weak Reference processing during an evacuation pause (part 2).
5566 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5567   double ref_enq_start = os::elapsedTime();
5568 
5569   ReferenceProcessor* rp = _ref_processor_stw;
5570   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5571 
5572   // Now enqueue any remaining on the discovered lists on to
5573   // the pending list.
5574   if (!rp->processing_is_mt()) {
5575     // Serial reference processing...
5576     rp->enqueue_discovered_references();
5577   } else {
5578     // Parallel reference enqueueing
5579 
5580     assert(no_of_gc_workers == workers()->active_workers(),
5581            "Need to reset active workers");
5582     assert(rp->num_q() == no_of_gc_workers, "sanity");
5583     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5584 
5585     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5586     rp->enqueue_discovered_references(&par_task_executor);
5587   }
5588 
5589   rp->verify_no_references_recorded();
5590   assert(!rp->discovery_enabled(), "should have been disabled");
5591 
5592   // FIXME
5593   // CM's reference processing also cleans up the string and symbol tables.
5594   // Should we do that here also? We could, but it is a serial operation
5595   // and could significantly increase the pause time.
5596 
5597   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5598   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5599 }
5600 
5601 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5602   _expand_heap_after_alloc_failure = true;
5603   _evacuation_failed = false;
5604 
5605   // Should G1EvacuationFailureALot be in effect for this GC?
5606   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5607 
5608   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5609 
5610   // Disable the hot card cache.
5611   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5612   hot_card_cache->reset_hot_cache_claimed_index();
5613   hot_card_cache->set_use_cache(false);
5614 
5615   uint n_workers;
5616   if (G1CollectedHeap::use_parallel_gc_threads()) {
5617     n_workers =
5618       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5619                                      workers()->active_workers(),
5620                                      Threads::number_of_non_daemon_threads());
5621     assert(UseDynamicNumberOfGCThreads ||
5622            n_workers == workers()->total_workers(),
5623            "If not dynamic should be using all the  workers");
5624     workers()->set_active_workers(n_workers);
5625     set_par_threads(n_workers);
5626   } else {
5627     assert(n_par_threads() == 0,
5628            "Should be the original non-parallel value");
5629     n_workers = 1;
5630   }
5631 
5632   G1ParTask g1_par_task(this, _task_queues);
5633 
5634   init_for_evac_failure(NULL);
5635 
5636   rem_set()->prepare_for_younger_refs_iterate(true);
5637 
5638   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5639   double start_par_time_sec = os::elapsedTime();
5640   double end_par_time_sec;
5641 
5642   {
5643     StrongRootsScope srs(this);
5644 
5645     if (G1CollectedHeap::use_parallel_gc_threads()) {
5646       // The individual threads will set their evac-failure closures.
5647       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5648       // These tasks use ShareHeap::_process_strong_tasks
5649       assert(UseDynamicNumberOfGCThreads ||
5650              workers()->active_workers() == workers()->total_workers(),
5651              "If not dynamic should be using all the  workers");
5652       workers()->run_task(&g1_par_task);
5653     } else {
5654       g1_par_task.set_for_termination(n_workers);
5655       g1_par_task.work(0);
5656     }
5657     end_par_time_sec = os::elapsedTime();
5658 
5659     // Closing the inner scope will execute the destructor
5660     // for the StrongRootsScope object. We record the current
5661     // elapsed time before closing the scope so that time
5662     // taken for the SRS destructor is NOT included in the
5663     // reported parallel time.
5664   }
5665 
5666   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5667   g1_policy()->phase_times()->record_par_time(par_time_ms);
5668 
5669   double code_root_fixup_time_ms =
5670         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5671   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5672 
5673   set_par_threads(0);
5674 
5675   // Process any discovered reference objects - we have
5676   // to do this _before_ we retire the GC alloc regions
5677   // as we may have to copy some 'reachable' referent
5678   // objects (and their reachable sub-graphs) that were
5679   // not copied during the pause.
5680   process_discovered_references(n_workers);
5681 
5682   // Weak root processing.
5683   {
5684     G1STWIsAliveClosure is_alive(this);
5685     G1KeepAliveClosure keep_alive(this);
5686     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5687     if (G1StringDedup::is_enabled()) {
5688       G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5689     }
5690   }
5691 
5692   release_gc_alloc_regions(n_workers, evacuation_info);
5693   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5694 
5695   // Reset and re-enable the hot card cache.
5696   // Note the counts for the cards in the regions in the
5697   // collection set are reset when the collection set is freed.
5698   hot_card_cache->reset_hot_cache();
5699   hot_card_cache->set_use_cache(true);
5700 
5701   // Migrate the strong code roots attached to each region in
5702   // the collection set. Ideally we would like to do this
5703   // after we have finished the scanning/evacuation of the
5704   // strong code roots for a particular heap region.
5705   migrate_strong_code_roots();
5706 
5707   purge_code_root_memory();
5708 
5709   if (g1_policy()->during_initial_mark_pause()) {
5710     // Reset the claim values set during marking the strong code roots
5711     reset_heap_region_claim_values();
5712   }
5713 
5714   finalize_for_evac_failure();
5715 
5716   if (evacuation_failed()) {
5717     remove_self_forwarding_pointers();
5718 
5719     // Reset the G1EvacuationFailureALot counters and flags
5720     // Note: the values are reset only when an actual
5721     // evacuation failure occurs.
5722     NOT_PRODUCT(reset_evacuation_should_fail();)
5723   }
5724 
5725   // Enqueue any remaining references remaining on the STW
5726   // reference processor's discovered lists. We need to do
5727   // this after the card table is cleaned (and verified) as
5728   // the act of enqueueing entries on to the pending list
5729   // will log these updates (and dirty their associated
5730   // cards). We need these updates logged to update any
5731   // RSets.
5732   enqueue_discovered_references(n_workers);
5733 
5734   if (G1DeferredRSUpdate) {
5735     redirty_logged_cards();
5736   }
5737   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5738 }
5739 
5740 void G1CollectedHeap::free_region(HeapRegion* hr,
5741                                   FreeRegionList* free_list,
5742                                   bool par,
5743                                   bool locked) {
5744   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5745   assert(!hr->is_empty(), "the region should not be empty");
5746   assert(free_list != NULL, "pre-condition");
5747 
5748   // Clear the card counts for this region.
5749   // Note: we only need to do this if the region is not young
5750   // (since we don't refine cards in young regions).
5751   if (!hr->is_young()) {
5752     _cg1r->hot_card_cache()->reset_card_counts(hr);
5753   }
5754   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5755   free_list->add_ordered(hr);
5756 }
5757 
5758 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5759                                      FreeRegionList* free_list,
5760                                      bool par) {
5761   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5762   assert(free_list != NULL, "pre-condition");
5763 
5764   size_t hr_capacity = hr->capacity();
5765   // We need to read this before we make the region non-humongous,
5766   // otherwise the information will be gone.
5767   uint last_index = hr->last_hc_index();
5768   hr->set_notHumongous();
5769   free_region(hr, free_list, par);
5770 
5771   uint i = hr->hrs_index() + 1;
5772   while (i < last_index) {
5773     HeapRegion* curr_hr = region_at(i);
5774     assert(curr_hr->continuesHumongous(), "invariant");
5775     curr_hr->set_notHumongous();
5776     free_region(curr_hr, free_list, par);
5777     i += 1;
5778   }
5779 }
5780 
5781 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5782                                        const HeapRegionSetCount& humongous_regions_removed) {
5783   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5784     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5785     _old_set.bulk_remove(old_regions_removed);
5786     _humongous_set.bulk_remove(humongous_regions_removed);
5787   }
5788 
5789 }
5790 
5791 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5792   assert(list != NULL, "list can't be null");
5793   if (!list->is_empty()) {
5794     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5795     _free_list.add_ordered(list);
5796   }
5797 }
5798 
5799 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5800   assert(_summary_bytes_used >= bytes,
5801          err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
5802                   _summary_bytes_used, bytes));
5803   _summary_bytes_used -= bytes;
5804 }
5805 
5806 class G1ParCleanupCTTask : public AbstractGangTask {
5807   G1SATBCardTableModRefBS* _ct_bs;
5808   G1CollectedHeap* _g1h;
5809   HeapRegion* volatile _su_head;
5810 public:
5811   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5812                      G1CollectedHeap* g1h) :
5813     AbstractGangTask("G1 Par Cleanup CT Task"),
5814     _ct_bs(ct_bs), _g1h(g1h) { }
5815 
5816   void work(uint worker_id) {
5817     HeapRegion* r;
5818     while (r = _g1h->pop_dirty_cards_region()) {
5819       clear_cards(r);
5820     }
5821   }
5822 
5823   void clear_cards(HeapRegion* r) {
5824     // Cards of the survivors should have already been dirtied.
5825     if (!r->is_survivor()) {
5826       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5827     }
5828   }
5829 };
5830 
5831 #ifndef PRODUCT
5832 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5833   G1CollectedHeap* _g1h;
5834   G1SATBCardTableModRefBS* _ct_bs;
5835 public:
5836   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5837     : _g1h(g1h), _ct_bs(ct_bs) { }
5838   virtual bool doHeapRegion(HeapRegion* r) {
5839     if (r->is_survivor()) {
5840       _g1h->verify_dirty_region(r);
5841     } else {
5842       _g1h->verify_not_dirty_region(r);
5843     }
5844     return false;
5845   }
5846 };
5847 
5848 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5849   // All of the region should be clean.
5850   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5851   MemRegion mr(hr->bottom(), hr->end());
5852   ct_bs->verify_not_dirty_region(mr);
5853 }
5854 
5855 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5856   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5857   // dirty allocated blocks as they allocate them. The thread that
5858   // retires each region and replaces it with a new one will do a
5859   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5860   // not dirty that area (one less thing to have to do while holding
5861   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5862   // is dirty.
5863   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5864   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5865   if (hr->is_young()) {
5866     ct_bs->verify_g1_young_region(mr);
5867   } else {
5868     ct_bs->verify_dirty_region(mr);
5869   }
5870 }
5871 
5872 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5873   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5874   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5875     verify_dirty_region(hr);
5876   }
5877 }
5878 
5879 void G1CollectedHeap::verify_dirty_young_regions() {
5880   verify_dirty_young_list(_young_list->first_region());
5881 }
5882 #endif
5883 
5884 void G1CollectedHeap::cleanUpCardTable() {
5885   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5886   double start = os::elapsedTime();
5887 
5888   {
5889     // Iterate over the dirty cards region list.
5890     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5891 
5892     if (G1CollectedHeap::use_parallel_gc_threads()) {
5893       set_par_threads();
5894       workers()->run_task(&cleanup_task);
5895       set_par_threads(0);
5896     } else {
5897       while (_dirty_cards_region_list) {
5898         HeapRegion* r = _dirty_cards_region_list;
5899         cleanup_task.clear_cards(r);
5900         _dirty_cards_region_list = r->get_next_dirty_cards_region();
5901         if (_dirty_cards_region_list == r) {
5902           // The last region.
5903           _dirty_cards_region_list = NULL;
5904         }
5905         r->set_next_dirty_cards_region(NULL);
5906       }
5907     }
5908 #ifndef PRODUCT
5909     if (G1VerifyCTCleanup || VerifyAfterGC) {
5910       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5911       heap_region_iterate(&cleanup_verifier);
5912     }
5913 #endif
5914   }
5915 
5916   double elapsed = os::elapsedTime() - start;
5917   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5918 }
5919 
5920 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5921   size_t pre_used = 0;
5922   FreeRegionList local_free_list("Local List for CSet Freeing");
5923 
5924   double young_time_ms     = 0.0;
5925   double non_young_time_ms = 0.0;
5926 
5927   // Since the collection set is a superset of the the young list,
5928   // all we need to do to clear the young list is clear its
5929   // head and length, and unlink any young regions in the code below
5930   _young_list->clear();
5931 
5932   G1CollectorPolicy* policy = g1_policy();
5933 
5934   double start_sec = os::elapsedTime();
5935   bool non_young = true;
5936 
5937   HeapRegion* cur = cs_head;
5938   int age_bound = -1;
5939   size_t rs_lengths = 0;
5940 
5941   while (cur != NULL) {
5942     assert(!is_on_master_free_list(cur), "sanity");
5943     if (non_young) {
5944       if (cur->is_young()) {
5945         double end_sec = os::elapsedTime();
5946         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5947         non_young_time_ms += elapsed_ms;
5948 
5949         start_sec = os::elapsedTime();
5950         non_young = false;
5951       }
5952     } else {
5953       if (!cur->is_young()) {
5954         double end_sec = os::elapsedTime();
5955         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5956         young_time_ms += elapsed_ms;
5957 
5958         start_sec = os::elapsedTime();
5959         non_young = true;
5960       }
5961     }
5962 
5963     rs_lengths += cur->rem_set()->occupied_locked();
5964 
5965     HeapRegion* next = cur->next_in_collection_set();
5966     assert(cur->in_collection_set(), "bad CS");
5967     cur->set_next_in_collection_set(NULL);
5968     cur->set_in_collection_set(false);
5969 
5970     if (cur->is_young()) {
5971       int index = cur->young_index_in_cset();
5972       assert(index != -1, "invariant");
5973       assert((uint) index < policy->young_cset_region_length(), "invariant");
5974       size_t words_survived = _surviving_young_words[index];
5975       cur->record_surv_words_in_group(words_survived);
5976 
5977       // At this point the we have 'popped' cur from the collection set
5978       // (linked via next_in_collection_set()) but it is still in the
5979       // young list (linked via next_young_region()). Clear the
5980       // _next_young_region field.
5981       cur->set_next_young_region(NULL);
5982     } else {
5983       int index = cur->young_index_in_cset();
5984       assert(index == -1, "invariant");
5985     }
5986 
5987     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5988             (!cur->is_young() && cur->young_index_in_cset() == -1),
5989             "invariant" );
5990 
5991     if (!cur->evacuation_failed()) {
5992       MemRegion used_mr = cur->used_region();
5993 
5994       // And the region is empty.
5995       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5996       pre_used += cur->used();
5997       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5998     } else {
5999       cur->uninstall_surv_rate_group();
6000       if (cur->is_young()) {
6001         cur->set_young_index_in_cset(-1);
6002       }
6003       cur->set_not_young();
6004       cur->set_evacuation_failed(false);
6005       // The region is now considered to be old.
6006       _old_set.add(cur);
6007       evacuation_info.increment_collectionset_used_after(cur->used());
6008     }
6009     cur = next;
6010   }
6011 
6012   evacuation_info.set_regions_freed(local_free_list.length());
6013   policy->record_max_rs_lengths(rs_lengths);
6014   policy->cset_regions_freed();
6015 
6016   double end_sec = os::elapsedTime();
6017   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6018 
6019   if (non_young) {
6020     non_young_time_ms += elapsed_ms;
6021   } else {
6022     young_time_ms += elapsed_ms;
6023   }
6024 
6025   prepend_to_freelist(&local_free_list);
6026   decrement_summary_bytes(pre_used);
6027   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6028   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6029 }
6030 
6031 // This routine is similar to the above but does not record
6032 // any policy statistics or update free lists; we are abandoning
6033 // the current incremental collection set in preparation of a
6034 // full collection. After the full GC we will start to build up
6035 // the incremental collection set again.
6036 // This is only called when we're doing a full collection
6037 // and is immediately followed by the tearing down of the young list.
6038 
6039 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6040   HeapRegion* cur = cs_head;
6041 
6042   while (cur != NULL) {
6043     HeapRegion* next = cur->next_in_collection_set();
6044     assert(cur->in_collection_set(), "bad CS");
6045     cur->set_next_in_collection_set(NULL);
6046     cur->set_in_collection_set(false);
6047     cur->set_young_index_in_cset(-1);
6048     cur = next;
6049   }
6050 }
6051 
6052 void G1CollectedHeap::set_free_regions_coming() {
6053   if (G1ConcRegionFreeingVerbose) {
6054     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6055                            "setting free regions coming");
6056   }
6057 
6058   assert(!free_regions_coming(), "pre-condition");
6059   _free_regions_coming = true;
6060 }
6061 
6062 void G1CollectedHeap::reset_free_regions_coming() {
6063   assert(free_regions_coming(), "pre-condition");
6064 
6065   {
6066     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6067     _free_regions_coming = false;
6068     SecondaryFreeList_lock->notify_all();
6069   }
6070 
6071   if (G1ConcRegionFreeingVerbose) {
6072     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6073                            "reset free regions coming");
6074   }
6075 }
6076 
6077 void G1CollectedHeap::wait_while_free_regions_coming() {
6078   // Most of the time we won't have to wait, so let's do a quick test
6079   // first before we take the lock.
6080   if (!free_regions_coming()) {
6081     return;
6082   }
6083 
6084   if (G1ConcRegionFreeingVerbose) {
6085     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6086                            "waiting for free regions");
6087   }
6088 
6089   {
6090     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6091     while (free_regions_coming()) {
6092       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6093     }
6094   }
6095 
6096   if (G1ConcRegionFreeingVerbose) {
6097     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6098                            "done waiting for free regions");
6099   }
6100 }
6101 
6102 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6103   assert(heap_lock_held_for_gc(),
6104               "the heap lock should already be held by or for this thread");
6105   _young_list->push_region(hr);
6106 }
6107 
6108 class NoYoungRegionsClosure: public HeapRegionClosure {
6109 private:
6110   bool _success;
6111 public:
6112   NoYoungRegionsClosure() : _success(true) { }
6113   bool doHeapRegion(HeapRegion* r) {
6114     if (r->is_young()) {
6115       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6116                              r->bottom(), r->end());
6117       _success = false;
6118     }
6119     return false;
6120   }
6121   bool success() { return _success; }
6122 };
6123 
6124 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6125   bool ret = _young_list->check_list_empty(check_sample);
6126 
6127   if (check_heap) {
6128     NoYoungRegionsClosure closure;
6129     heap_region_iterate(&closure);
6130     ret = ret && closure.success();
6131   }
6132 
6133   return ret;
6134 }
6135 
6136 class TearDownRegionSetsClosure : public HeapRegionClosure {
6137 private:
6138   HeapRegionSet *_old_set;
6139 
6140 public:
6141   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6142 
6143   bool doHeapRegion(HeapRegion* r) {
6144     if (r->is_empty()) {
6145       // We ignore empty regions, we'll empty the free list afterwards
6146     } else if (r->is_young()) {
6147       // We ignore young regions, we'll empty the young list afterwards
6148     } else if (r->isHumongous()) {
6149       // We ignore humongous regions, we're not tearing down the
6150       // humongous region set
6151     } else {
6152       // The rest should be old
6153       _old_set->remove(r);
6154     }
6155     return false;
6156   }
6157 
6158   ~TearDownRegionSetsClosure() {
6159     assert(_old_set->is_empty(), "post-condition");
6160   }
6161 };
6162 
6163 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6164   assert_at_safepoint(true /* should_be_vm_thread */);
6165 
6166   if (!free_list_only) {
6167     TearDownRegionSetsClosure cl(&_old_set);
6168     heap_region_iterate(&cl);
6169 
6170     // Note that emptying the _young_list is postponed and instead done as
6171     // the first step when rebuilding the regions sets again. The reason for
6172     // this is that during a full GC string deduplication needs to know if
6173     // a collected region was young or old when the full GC was initiated.
6174   }
6175   _free_list.remove_all();
6176 }
6177 
6178 class RebuildRegionSetsClosure : public HeapRegionClosure {
6179 private:
6180   bool            _free_list_only;
6181   HeapRegionSet*   _old_set;
6182   FreeRegionList* _free_list;
6183   size_t          _total_used;
6184 
6185 public:
6186   RebuildRegionSetsClosure(bool free_list_only,
6187                            HeapRegionSet* old_set, FreeRegionList* free_list) :
6188     _free_list_only(free_list_only),
6189     _old_set(old_set), _free_list(free_list), _total_used(0) {
6190     assert(_free_list->is_empty(), "pre-condition");
6191     if (!free_list_only) {
6192       assert(_old_set->is_empty(), "pre-condition");
6193     }
6194   }
6195 
6196   bool doHeapRegion(HeapRegion* r) {
6197     if (r->continuesHumongous()) {
6198       return false;
6199     }
6200 
6201     if (r->is_empty()) {
6202       // Add free regions to the free list
6203       _free_list->add_as_tail(r);
6204     } else if (!_free_list_only) {
6205       assert(!r->is_young(), "we should not come across young regions");
6206 
6207       if (r->isHumongous()) {
6208         // We ignore humongous regions, we left the humongous set unchanged
6209       } else {
6210         // The rest should be old, add them to the old set
6211         _old_set->add(r);
6212       }
6213       _total_used += r->used();
6214     }
6215 
6216     return false;
6217   }
6218 
6219   size_t total_used() {
6220     return _total_used;
6221   }
6222 };
6223 
6224 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6225   assert_at_safepoint(true /* should_be_vm_thread */);
6226 
6227   if (!free_list_only) {
6228     _young_list->empty_list();
6229   }
6230 
6231   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6232   heap_region_iterate(&cl);
6233 
6234   if (!free_list_only) {
6235     _summary_bytes_used = cl.total_used();
6236   }
6237   assert(_summary_bytes_used == recalculate_used(),
6238          err_msg("inconsistent _summary_bytes_used, "
6239                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6240                  _summary_bytes_used, recalculate_used()));
6241 }
6242 
6243 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6244   _refine_cte_cl->set_concurrent(concurrent);
6245 }
6246 
6247 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6248   HeapRegion* hr = heap_region_containing(p);
6249   if (hr == NULL) {
6250     return false;
6251   } else {
6252     return hr->is_in(p);
6253   }
6254 }
6255 
6256 // Methods for the mutator alloc region
6257 
6258 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6259                                                       bool force) {
6260   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6261   assert(!force || g1_policy()->can_expand_young_list(),
6262          "if force is true we should be able to expand the young list");
6263   bool young_list_full = g1_policy()->is_young_list_full();
6264   if (force || !young_list_full) {
6265     HeapRegion* new_alloc_region = new_region(word_size,
6266                                               false /* is_old */,
6267                                               false /* do_expand */);
6268     if (new_alloc_region != NULL) {
6269       set_region_short_lived_locked(new_alloc_region);
6270       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6271       return new_alloc_region;
6272     }
6273   }
6274   return NULL;
6275 }
6276 
6277 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6278                                                   size_t allocated_bytes) {
6279   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6280   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6281 
6282   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6283   _summary_bytes_used += allocated_bytes;
6284   _hr_printer.retire(alloc_region);
6285   // We update the eden sizes here, when the region is retired,
6286   // instead of when it's allocated, since this is the point that its
6287   // used space has been recored in _summary_bytes_used.
6288   g1mm()->update_eden_size();
6289 }
6290 
6291 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6292                                                     bool force) {
6293   return _g1h->new_mutator_alloc_region(word_size, force);
6294 }
6295 
6296 void G1CollectedHeap::set_par_threads() {
6297   // Don't change the number of workers.  Use the value previously set
6298   // in the workgroup.
6299   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6300   uint n_workers = workers()->active_workers();
6301   assert(UseDynamicNumberOfGCThreads ||
6302            n_workers == workers()->total_workers(),
6303       "Otherwise should be using the total number of workers");
6304   if (n_workers == 0) {
6305     assert(false, "Should have been set in prior evacuation pause.");
6306     n_workers = ParallelGCThreads;
6307     workers()->set_active_workers(n_workers);
6308   }
6309   set_par_threads(n_workers);
6310 }
6311 
6312 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6313                                        size_t allocated_bytes) {
6314   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6315 }
6316 
6317 // Methods for the GC alloc regions
6318 
6319 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6320                                                  uint count,
6321                                                  GCAllocPurpose ap) {
6322   assert(FreeList_lock->owned_by_self(), "pre-condition");
6323 
6324   if (count < g1_policy()->max_regions(ap)) {
6325     bool survivor = (ap == GCAllocForSurvived);
6326     HeapRegion* new_alloc_region = new_region(word_size,
6327                                               !survivor,
6328                                               true /* do_expand */);
6329     if (new_alloc_region != NULL) {
6330       // We really only need to do this for old regions given that we
6331       // should never scan survivors. But it doesn't hurt to do it
6332       // for survivors too.
6333       new_alloc_region->set_saved_mark();
6334       if (survivor) {
6335         new_alloc_region->set_survivor();
6336         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6337       } else {
6338         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6339       }
6340       bool during_im = g1_policy()->during_initial_mark_pause();
6341       new_alloc_region->note_start_of_copying(during_im);
6342       return new_alloc_region;
6343     } else {
6344       g1_policy()->note_alloc_region_limit_reached(ap);
6345     }
6346   }
6347   return NULL;
6348 }
6349 
6350 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6351                                              size_t allocated_bytes,
6352                                              GCAllocPurpose ap) {
6353   bool during_im = g1_policy()->during_initial_mark_pause();
6354   alloc_region->note_end_of_copying(during_im);
6355   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6356   if (ap == GCAllocForSurvived) {
6357     young_list()->add_survivor_region(alloc_region);
6358   } else {
6359     _old_set.add(alloc_region);
6360   }
6361   _hr_printer.retire(alloc_region);
6362 }
6363 
6364 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6365                                                        bool force) {
6366   assert(!force, "not supported for GC alloc regions");
6367   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6368 }
6369 
6370 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6371                                           size_t allocated_bytes) {
6372   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6373                                GCAllocForSurvived);
6374 }
6375 
6376 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6377                                                   bool force) {
6378   assert(!force, "not supported for GC alloc regions");
6379   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6380 }
6381 
6382 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6383                                      size_t allocated_bytes) {
6384   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6385                                GCAllocForTenured);
6386 }
6387 // Heap region set verification
6388 
6389 class VerifyRegionListsClosure : public HeapRegionClosure {
6390 private:
6391   HeapRegionSet*   _old_set;
6392   HeapRegionSet*   _humongous_set;
6393   FreeRegionList*  _free_list;
6394 
6395 public:
6396   HeapRegionSetCount _old_count;
6397   HeapRegionSetCount _humongous_count;
6398   HeapRegionSetCount _free_count;
6399 
6400   VerifyRegionListsClosure(HeapRegionSet* old_set,
6401                            HeapRegionSet* humongous_set,
6402                            FreeRegionList* free_list) :
6403     _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6404     _old_count(), _humongous_count(), _free_count(){ }
6405 
6406   bool doHeapRegion(HeapRegion* hr) {
6407     if (hr->continuesHumongous()) {
6408       return false;
6409     }
6410 
6411     if (hr->is_young()) {
6412       // TODO
6413     } else if (hr->startsHumongous()) {
6414       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num()));
6415       _humongous_count.increment(1u, hr->capacity());
6416     } else if (hr->is_empty()) {
6417       assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num()));
6418       _free_count.increment(1u, hr->capacity());
6419     } else {
6420       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num()));
6421       _old_count.increment(1u, hr->capacity());
6422     }
6423     return false;
6424   }
6425 
6426   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6427     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6428     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6429         old_set->total_capacity_bytes(), _old_count.capacity()));
6430 
6431     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6432     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6433         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6434 
6435     guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6436     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6437         free_list->total_capacity_bytes(), _free_count.capacity()));
6438   }
6439 };
6440 
6441 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6442                                              HeapWord* bottom) {
6443   HeapWord* end = bottom + HeapRegion::GrainWords;
6444   MemRegion mr(bottom, end);
6445   assert(_g1_reserved.contains(mr), "invariant");
6446   // This might return NULL if the allocation fails
6447   return new HeapRegion(hrs_index, _bot_shared, mr);
6448 }
6449 
6450 void G1CollectedHeap::verify_region_sets() {
6451   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6452 
6453   // First, check the explicit lists.
6454   _free_list.verify_list();
6455   {
6456     // Given that a concurrent operation might be adding regions to
6457     // the secondary free list we have to take the lock before
6458     // verifying it.
6459     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6460     _secondary_free_list.verify_list();
6461   }
6462 
6463   // If a concurrent region freeing operation is in progress it will
6464   // be difficult to correctly attributed any free regions we come
6465   // across to the correct free list given that they might belong to
6466   // one of several (free_list, secondary_free_list, any local lists,
6467   // etc.). So, if that's the case we will skip the rest of the
6468   // verification operation. Alternatively, waiting for the concurrent
6469   // operation to complete will have a non-trivial effect on the GC's
6470   // operation (no concurrent operation will last longer than the
6471   // interval between two calls to verification) and it might hide
6472   // any issues that we would like to catch during testing.
6473   if (free_regions_coming()) {
6474     return;
6475   }
6476 
6477   // Make sure we append the secondary_free_list on the free_list so
6478   // that all free regions we will come across can be safely
6479   // attributed to the free_list.
6480   append_secondary_free_list_if_not_empty_with_lock();
6481 
6482   // Finally, make sure that the region accounting in the lists is
6483   // consistent with what we see in the heap.
6484 
6485   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6486   heap_region_iterate(&cl);
6487   cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6488 }
6489 
6490 // Optimized nmethod scanning
6491 
6492 class RegisterNMethodOopClosure: public OopClosure {
6493   G1CollectedHeap* _g1h;
6494   nmethod* _nm;
6495 
6496   template <class T> void do_oop_work(T* p) {
6497     T heap_oop = oopDesc::load_heap_oop(p);
6498     if (!oopDesc::is_null(heap_oop)) {
6499       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6500       HeapRegion* hr = _g1h->heap_region_containing(obj);
6501       assert(!hr->continuesHumongous(),
6502              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6503                      " starting at "HR_FORMAT,
6504                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6505 
6506       // HeapRegion::add_strong_code_root() avoids adding duplicate
6507       // entries but having duplicates is  OK since we "mark" nmethods
6508       // as visited when we scan the strong code root lists during the GC.
6509       hr->add_strong_code_root(_nm);
6510       assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6511              err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6512                      _nm, HR_FORMAT_PARAMS(hr)));
6513     }
6514   }
6515 
6516 public:
6517   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6518     _g1h(g1h), _nm(nm) {}
6519 
6520   void do_oop(oop* p)       { do_oop_work(p); }
6521   void do_oop(narrowOop* p) { do_oop_work(p); }
6522 };
6523 
6524 class UnregisterNMethodOopClosure: public OopClosure {
6525   G1CollectedHeap* _g1h;
6526   nmethod* _nm;
6527 
6528   template <class T> void do_oop_work(T* p) {
6529     T heap_oop = oopDesc::load_heap_oop(p);
6530     if (!oopDesc::is_null(heap_oop)) {
6531       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6532       HeapRegion* hr = _g1h->heap_region_containing(obj);
6533       assert(!hr->continuesHumongous(),
6534              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6535                      " starting at "HR_FORMAT,
6536                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6537 
6538       hr->remove_strong_code_root(_nm);
6539       assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6540              err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6541                      _nm, HR_FORMAT_PARAMS(hr)));
6542     }
6543   }
6544 
6545 public:
6546   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6547     _g1h(g1h), _nm(nm) {}
6548 
6549   void do_oop(oop* p)       { do_oop_work(p); }
6550   void do_oop(narrowOop* p) { do_oop_work(p); }
6551 };
6552 
6553 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6554   CollectedHeap::register_nmethod(nm);
6555 
6556   guarantee(nm != NULL, "sanity");
6557   RegisterNMethodOopClosure reg_cl(this, nm);
6558   nm->oops_do(&reg_cl);
6559 }
6560 
6561 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6562   CollectedHeap::unregister_nmethod(nm);
6563 
6564   guarantee(nm != NULL, "sanity");
6565   UnregisterNMethodOopClosure reg_cl(this, nm);
6566   nm->oops_do(&reg_cl, true);
6567 }
6568 
6569 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6570 public:
6571   bool doHeapRegion(HeapRegion *hr) {
6572     assert(!hr->isHumongous(),
6573            err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6574                    HR_FORMAT_PARAMS(hr)));
6575     hr->migrate_strong_code_roots();
6576     return false;
6577   }
6578 };
6579 
6580 void G1CollectedHeap::migrate_strong_code_roots() {
6581   MigrateCodeRootsHeapRegionClosure cl;
6582   double migrate_start = os::elapsedTime();
6583   collection_set_iterate(&cl);
6584   double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6585   g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6586 }
6587 
6588 void G1CollectedHeap::purge_code_root_memory() {
6589   double purge_start = os::elapsedTime();
6590   G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6591   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6592   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6593 }
6594 
6595 // Mark all the code roots that point into regions *not* in the
6596 // collection set.
6597 //
6598 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6599 // walking the the code roots lists of regions not in the collection
6600 // set. Suppose we have an nmethod (M) that points to objects in two
6601 // separate regions - one in the collection set (R1) and one not (R2).
6602 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6603 // nmethod M when walking the code roots for R1. When we come to scan
6604 // the code roots for R2, we would see that M is already marked and it
6605 // would be skipped and the objects in R2 that are referenced from M
6606 // would not be evacuated.
6607 
6608 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6609 
6610   class MarkStrongCodeRootOopClosure: public OopClosure {
6611     ConcurrentMark* _cm;
6612     HeapRegion* _hr;
6613     uint _worker_id;
6614 
6615     template <class T> void do_oop_work(T* p) {
6616       T heap_oop = oopDesc::load_heap_oop(p);
6617       if (!oopDesc::is_null(heap_oop)) {
6618         oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6619         // Only mark objects in the region (which is assumed
6620         // to be not in the collection set).
6621         if (_hr->is_in(obj)) {
6622           _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6623         }
6624       }
6625     }
6626 
6627   public:
6628     MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6629       _cm(cm), _hr(hr), _worker_id(worker_id) {
6630       assert(!_hr->in_collection_set(), "sanity");
6631     }
6632 
6633     void do_oop(narrowOop* p) { do_oop_work(p); }
6634     void do_oop(oop* p)       { do_oop_work(p); }
6635   };
6636 
6637   MarkStrongCodeRootOopClosure _oop_cl;
6638 
6639 public:
6640   MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6641     _oop_cl(cm, hr, worker_id) {}
6642 
6643   void do_code_blob(CodeBlob* cb) {
6644     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6645     if (nm != NULL) {
6646       nm->oops_do(&_oop_cl);
6647     }
6648   }
6649 };
6650 
6651 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6652   G1CollectedHeap* _g1h;
6653   uint _worker_id;
6654 
6655 public:
6656   MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6657     _g1h(g1h), _worker_id(worker_id) {}
6658 
6659   bool doHeapRegion(HeapRegion *hr) {
6660     HeapRegionRemSet* hrrs = hr->rem_set();
6661     if (hr->continuesHumongous()) {
6662       // Code roots should never be attached to a continuation of a humongous region
6663       assert(hrrs->strong_code_roots_list_length() == 0,
6664              err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6665                      " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6666                      HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6667                      hrrs->strong_code_roots_list_length()));
6668       return false;
6669     }
6670 
6671     if (hr->in_collection_set()) {
6672       // Don't mark code roots into regions in the collection set here.
6673       // They will be marked when we scan them.
6674       return false;
6675     }
6676 
6677     MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6678     hr->strong_code_roots_do(&cb_cl);
6679     return false;
6680   }
6681 };
6682 
6683 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6684   MarkStrongCodeRootsHRClosure cl(this, worker_id);
6685   if (G1CollectedHeap::use_parallel_gc_threads()) {
6686     heap_region_par_iterate_chunked(&cl,
6687                                     worker_id,
6688                                     workers()->active_workers(),
6689                                     HeapRegion::ParMarkRootClaimValue);
6690   } else {
6691     heap_region_iterate(&cl);
6692   }
6693 }
6694 
6695 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6696   G1CollectedHeap* _g1h;
6697 
6698 public:
6699   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6700     _g1h(g1h) {}
6701 
6702   void do_code_blob(CodeBlob* cb) {
6703     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6704     if (nm == NULL) {
6705       return;
6706     }
6707 
6708     if (ScavengeRootsInCode) {
6709       _g1h->register_nmethod(nm);
6710     }
6711   }
6712 };
6713 
6714 void G1CollectedHeap::rebuild_strong_code_roots() {
6715   RebuildStrongCodeRootClosure blob_cl(this);
6716   CodeCache::blobs_do(&blob_cl);
6717 }