1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #if !defined(__clang_major__) && defined(__GNUC__)
  26 // FIXME, formats have issues.  Disable this macro definition, compile, and study warnings for more information.
  27 #define ATTRIBUTE_PRINTF(x,y)
  28 #endif
  29 
  30 #include "precompiled.hpp"
  31 #include "classfile/metadataOnStackMark.hpp"
  32 #include "classfile/stringTable.hpp"
  33 #include "code/codeCache.hpp"
  34 #include "code/icBuffer.hpp"
  35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  43 #include "gc_implementation/g1/g1EvacFailure.hpp"
  44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  45 #include "gc_implementation/g1/g1Log.hpp"
  46 #include "gc_implementation/g1/g1MarkSweep.hpp"
  47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
  49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
  50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  51 #include "gc_implementation/g1/g1RootProcessor.hpp"
  52 #include "gc_implementation/g1/g1StringDedup.hpp"
  53 #include "gc_implementation/g1/g1YCTypes.hpp"
  54 #include "gc_implementation/g1/heapRegion.inline.hpp"
  55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
  57 #include "gc_implementation/g1/vm_operations_g1.hpp"
  58 #include "gc_implementation/shared/gcHeapSummary.hpp"
  59 #include "gc_implementation/shared/gcTimer.hpp"
  60 #include "gc_implementation/shared/gcTrace.hpp"
  61 #include "gc_implementation/shared/gcTraceTime.hpp"
  62 #include "gc_implementation/shared/isGCActiveMark.hpp"
  63 #include "memory/allocation.hpp"
  64 #include "memory/gcLocker.inline.hpp"
  65 #include "memory/generationSpec.hpp"
  66 #include "memory/iterator.hpp"
  67 #include "memory/referenceProcessor.hpp"
  68 #include "oops/oop.inline.hpp"
  69 #include "runtime/atomic.inline.hpp"
  70 #include "runtime/orderAccess.inline.hpp"
  71 #include "runtime/vmThread.hpp"
  72 #include "utilities/globalDefinitions.hpp"
  73 
  74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  75 
  76 // turn it on so that the contents of the young list (scan-only /
  77 // to-be-collected) are printed at "strategic" points before / during
  78 // / after the collection --- this is useful for debugging
  79 #define YOUNG_LIST_VERBOSE 0
  80 // CURRENT STATUS
  81 // This file is under construction.  Search for "FIXME".
  82 
  83 // INVARIANTS/NOTES
  84 //
  85 // All allocation activity covered by the G1CollectedHeap interface is
  86 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  87 // and allocate_new_tlab, which are the "entry" points to the
  88 // allocation code from the rest of the JVM.  (Note that this does not
  89 // apply to TLAB allocation, which is not part of this interface: it
  90 // is done by clients of this interface.)
  91 
  92 // Local to this file.
  93 
  94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  95   bool _concurrent;
  96 public:
  97   RefineCardTableEntryClosure() : _concurrent(true) { }
  98 
  99   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 100     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 101     // This path is executed by the concurrent refine or mutator threads,
 102     // concurrently, and so we do not care if card_ptr contains references
 103     // that point into the collection set.
 104     assert(!oops_into_cset, "should be");
 105 
 106     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 107       // Caller will actually yield.
 108       return false;
 109     }
 110     // Otherwise, we finished successfully; return true.
 111     return true;
 112   }
 113 
 114   void set_concurrent(bool b) { _concurrent = b; }
 115 };
 116 
 117 
 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 119  private:
 120   size_t _num_processed;
 121 
 122  public:
 123   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 124 
 125   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 126     *card_ptr = CardTableModRefBS::dirty_card_val();
 127     _num_processed++;
 128     return true;
 129   }
 130 
 131   size_t num_processed() const { return _num_processed; }
 132 };
 133 
 134 YoungList::YoungList(G1CollectedHeap* g1h) :
 135     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 136     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 137   guarantee(check_list_empty(false), "just making sure...");
 138 }
 139 
 140 void YoungList::push_region(HeapRegion *hr) {
 141   assert(!hr->is_young(), "should not already be young");
 142   assert(hr->get_next_young_region() == NULL, "cause it should!");
 143 
 144   hr->set_next_young_region(_head);
 145   _head = hr;
 146 
 147   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 148   ++_length;
 149 }
 150 
 151 void YoungList::add_survivor_region(HeapRegion* hr) {
 152   assert(hr->is_survivor(), "should be flagged as survivor region");
 153   assert(hr->get_next_young_region() == NULL, "cause it should!");
 154 
 155   hr->set_next_young_region(_survivor_head);
 156   if (_survivor_head == NULL) {
 157     _survivor_tail = hr;
 158   }
 159   _survivor_head = hr;
 160   ++_survivor_length;
 161 }
 162 
 163 void YoungList::empty_list(HeapRegion* list) {
 164   while (list != NULL) {
 165     HeapRegion* next = list->get_next_young_region();
 166     list->set_next_young_region(NULL);
 167     list->uninstall_surv_rate_group();
 168     // This is called before a Full GC and all the non-empty /
 169     // non-humongous regions at the end of the Full GC will end up as
 170     // old anyway.
 171     list->set_old();
 172     list = next;
 173   }
 174 }
 175 
 176 void YoungList::empty_list() {
 177   assert(check_list_well_formed(), "young list should be well formed");
 178 
 179   empty_list(_head);
 180   _head = NULL;
 181   _length = 0;
 182 
 183   empty_list(_survivor_head);
 184   _survivor_head = NULL;
 185   _survivor_tail = NULL;
 186   _survivor_length = 0;
 187 
 188   _last_sampled_rs_lengths = 0;
 189 
 190   assert(check_list_empty(false), "just making sure...");
 191 }
 192 
 193 bool YoungList::check_list_well_formed() {
 194   bool ret = true;
 195 
 196   uint length = 0;
 197   HeapRegion* curr = _head;
 198   HeapRegion* last = NULL;
 199   while (curr != NULL) {
 200     if (!curr->is_young()) {
 201       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 202                              "incorrectly tagged (y: %d, surv: %d)",
 203                              curr->bottom(), curr->end(),
 204                              curr->is_young(), curr->is_survivor());
 205       ret = false;
 206     }
 207     ++length;
 208     last = curr;
 209     curr = curr->get_next_young_region();
 210   }
 211   ret = ret && (length == _length);
 212 
 213   if (!ret) {
 214     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 215     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 216                            length, _length);
 217   }
 218 
 219   return ret;
 220 }
 221 
 222 bool YoungList::check_list_empty(bool check_sample) {
 223   bool ret = true;
 224 
 225   if (_length != 0) {
 226     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 227                   _length);
 228     ret = false;
 229   }
 230   if (check_sample && _last_sampled_rs_lengths != 0) {
 231     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 232     ret = false;
 233   }
 234   if (_head != NULL) {
 235     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 236     ret = false;
 237   }
 238   if (!ret) {
 239     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 240   }
 241 
 242   return ret;
 243 }
 244 
 245 void
 246 YoungList::rs_length_sampling_init() {
 247   _sampled_rs_lengths = 0;
 248   _curr               = _head;
 249 }
 250 
 251 bool
 252 YoungList::rs_length_sampling_more() {
 253   return _curr != NULL;
 254 }
 255 
 256 void
 257 YoungList::rs_length_sampling_next() {
 258   assert( _curr != NULL, "invariant" );
 259   size_t rs_length = _curr->rem_set()->occupied();
 260 
 261   _sampled_rs_lengths += rs_length;
 262 
 263   // The current region may not yet have been added to the
 264   // incremental collection set (it gets added when it is
 265   // retired as the current allocation region).
 266   if (_curr->in_collection_set()) {
 267     // Update the collection set policy information for this region
 268     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 269   }
 270 
 271   _curr = _curr->get_next_young_region();
 272   if (_curr == NULL) {
 273     _last_sampled_rs_lengths = _sampled_rs_lengths;
 274     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 275   }
 276 }
 277 
 278 void
 279 YoungList::reset_auxilary_lists() {
 280   guarantee( is_empty(), "young list should be empty" );
 281   assert(check_list_well_formed(), "young list should be well formed");
 282 
 283   // Add survivor regions to SurvRateGroup.
 284   _g1h->g1_policy()->note_start_adding_survivor_regions();
 285   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 286 
 287   int young_index_in_cset = 0;
 288   for (HeapRegion* curr = _survivor_head;
 289        curr != NULL;
 290        curr = curr->get_next_young_region()) {
 291     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 292 
 293     // The region is a non-empty survivor so let's add it to
 294     // the incremental collection set for the next evacuation
 295     // pause.
 296     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 297     young_index_in_cset += 1;
 298   }
 299   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 300   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 301 
 302   _head   = _survivor_head;
 303   _length = _survivor_length;
 304   if (_survivor_head != NULL) {
 305     assert(_survivor_tail != NULL, "cause it shouldn't be");
 306     assert(_survivor_length > 0, "invariant");
 307     _survivor_tail->set_next_young_region(NULL);
 308   }
 309 
 310   // Don't clear the survivor list handles until the start of
 311   // the next evacuation pause - we need it in order to re-tag
 312   // the survivor regions from this evacuation pause as 'young'
 313   // at the start of the next.
 314 
 315   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 316 
 317   assert(check_list_well_formed(), "young list should be well formed");
 318 }
 319 
 320 void YoungList::print() {
 321   HeapRegion* lists[] = {_head,   _survivor_head};
 322   const char* names[] = {"YOUNG", "SURVIVOR"};
 323 
 324   for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
 325     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 326     HeapRegion *curr = lists[list];
 327     if (curr == NULL)
 328       gclog_or_tty->print_cr("  empty");
 329     while (curr != NULL) {
 330       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
 331                              HR_FORMAT_PARAMS(curr),
 332                              curr->prev_top_at_mark_start(),
 333                              curr->next_top_at_mark_start(),
 334                              curr->age_in_surv_rate_group_cond());
 335       curr = curr->get_next_young_region();
 336     }
 337   }
 338 
 339   gclog_or_tty->cr();
 340 }
 341 
 342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 343   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 344 }
 345 
 346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 347   // The from card cache is not the memory that is actually committed. So we cannot
 348   // take advantage of the zero_filled parameter.
 349   reset_from_card_cache(start_idx, num_regions);
 350 }
 351 
 352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 353 {
 354   // Claim the right to put the region on the dirty cards region list
 355   // by installing a self pointer.
 356   HeapRegion* next = hr->get_next_dirty_cards_region();
 357   if (next == NULL) {
 358     HeapRegion* res = (HeapRegion*)
 359       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 360                           NULL);
 361     if (res == NULL) {
 362       HeapRegion* head;
 363       do {
 364         // Put the region to the dirty cards region list.
 365         head = _dirty_cards_region_list;
 366         next = (HeapRegion*)
 367           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 368         if (next == head) {
 369           assert(hr->get_next_dirty_cards_region() == hr,
 370                  "hr->get_next_dirty_cards_region() != hr");
 371           if (next == NULL) {
 372             // The last region in the list points to itself.
 373             hr->set_next_dirty_cards_region(hr);
 374           } else {
 375             hr->set_next_dirty_cards_region(next);
 376           }
 377         }
 378       } while (next != head);
 379     }
 380   }
 381 }
 382 
 383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 384 {
 385   HeapRegion* head;
 386   HeapRegion* hr;
 387   do {
 388     head = _dirty_cards_region_list;
 389     if (head == NULL) {
 390       return NULL;
 391     }
 392     HeapRegion* new_head = head->get_next_dirty_cards_region();
 393     if (head == new_head) {
 394       // The last region.
 395       new_head = NULL;
 396     }
 397     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 398                                           head);
 399   } while (hr != head);
 400   assert(hr != NULL, "invariant");
 401   hr->set_next_dirty_cards_region(NULL);
 402   return hr;
 403 }
 404 
 405 // Returns true if the reference points to an object that
 406 // can move in an incremental collection.
 407 bool G1CollectedHeap::is_scavengable(const void* p) {
 408   HeapRegion* hr = heap_region_containing(p);
 409   return !hr->is_humongous();
 410 }
 411 
 412 // Private class members.
 413 
 414 G1CollectedHeap* G1CollectedHeap::_g1h;
 415 
 416 // Private methods.
 417 
 418 HeapRegion*
 419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 420   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 421   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 422     if (!_secondary_free_list.is_empty()) {
 423       if (G1ConcRegionFreeingVerbose) {
 424         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 425                                "secondary_free_list has %u entries",
 426                                _secondary_free_list.length());
 427       }
 428       // It looks as if there are free regions available on the
 429       // secondary_free_list. Let's move them to the free_list and try
 430       // again to allocate from it.
 431       append_secondary_free_list();
 432 
 433       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 434              "empty we should have moved at least one entry to the free_list");
 435       HeapRegion* res = _hrm.allocate_free_region(is_old);
 436       if (G1ConcRegionFreeingVerbose) {
 437         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 438                                "allocated "HR_FORMAT" from secondary_free_list",
 439                                HR_FORMAT_PARAMS(res));
 440       }
 441       return res;
 442     }
 443 
 444     // Wait here until we get notified either when (a) there are no
 445     // more free regions coming or (b) some regions have been moved on
 446     // the secondary_free_list.
 447     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 448   }
 449 
 450   if (G1ConcRegionFreeingVerbose) {
 451     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 452                            "could not allocate from secondary_free_list");
 453   }
 454   return NULL;
 455 }
 456 
 457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 458   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 459          "the only time we use this to allocate a humongous region is "
 460          "when we are allocating a single humongous region");
 461 
 462   HeapRegion* res;
 463   if (G1StressConcRegionFreeing) {
 464     if (!_secondary_free_list.is_empty()) {
 465       if (G1ConcRegionFreeingVerbose) {
 466         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 467                                "forced to look at the secondary_free_list");
 468       }
 469       res = new_region_try_secondary_free_list(is_old);
 470       if (res != NULL) {
 471         return res;
 472       }
 473     }
 474   }
 475 
 476   res = _hrm.allocate_free_region(is_old);
 477 
 478   if (res == NULL) {
 479     if (G1ConcRegionFreeingVerbose) {
 480       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 481                              "res == NULL, trying the secondary_free_list");
 482     }
 483     res = new_region_try_secondary_free_list(is_old);
 484   }
 485   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 486     // Currently, only attempts to allocate GC alloc regions set
 487     // do_expand to true. So, we should only reach here during a
 488     // safepoint. If this assumption changes we might have to
 489     // reconsider the use of _expand_heap_after_alloc_failure.
 490     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 491 
 492     ergo_verbose1(ErgoHeapSizing,
 493                   "attempt heap expansion",
 494                   ergo_format_reason("region allocation request failed")
 495                   ergo_format_byte("allocation request"),
 496                   word_size * HeapWordSize);
 497     if (expand(word_size * HeapWordSize)) {
 498       // Given that expand() succeeded in expanding the heap, and we
 499       // always expand the heap by an amount aligned to the heap
 500       // region size, the free list should in theory not be empty.
 501       // In either case allocate_free_region() will check for NULL.
 502       res = _hrm.allocate_free_region(is_old);
 503     } else {
 504       _expand_heap_after_alloc_failure = false;
 505     }
 506   }
 507   return res;
 508 }
 509 
 510 HeapWord*
 511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 512                                                            uint num_regions,
 513                                                            size_t word_size,
 514                                                            AllocationContext_t context) {
 515   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 516   assert(is_humongous(word_size), "word_size should be humongous");
 517   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 518 
 519   // Index of last region in the series + 1.
 520   uint last = first + num_regions;
 521 
 522   // We need to initialize the region(s) we just discovered. This is
 523   // a bit tricky given that it can happen concurrently with
 524   // refinement threads refining cards on these regions and
 525   // potentially wanting to refine the BOT as they are scanning
 526   // those cards (this can happen shortly after a cleanup; see CR
 527   // 6991377). So we have to set up the region(s) carefully and in
 528   // a specific order.
 529 
 530   // The word size sum of all the regions we will allocate.
 531   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 532   assert(word_size <= word_size_sum, "sanity");
 533 
 534   // This will be the "starts humongous" region.
 535   HeapRegion* first_hr = region_at(first);
 536   // The header of the new object will be placed at the bottom of
 537   // the first region.
 538   HeapWord* new_obj = first_hr->bottom();
 539   // This will be the new end of the first region in the series that
 540   // should also match the end of the last region in the series.
 541   HeapWord* new_end = new_obj + word_size_sum;
 542   // This will be the new top of the first region that will reflect
 543   // this allocation.
 544   HeapWord* new_top = new_obj + word_size;
 545 
 546   // First, we need to zero the header of the space that we will be
 547   // allocating. When we update top further down, some refinement
 548   // threads might try to scan the region. By zeroing the header we
 549   // ensure that any thread that will try to scan the region will
 550   // come across the zero klass word and bail out.
 551   //
 552   // NOTE: It would not have been correct to have used
 553   // CollectedHeap::fill_with_object() and make the space look like
 554   // an int array. The thread that is doing the allocation will
 555   // later update the object header to a potentially different array
 556   // type and, for a very short period of time, the klass and length
 557   // fields will be inconsistent. This could cause a refinement
 558   // thread to calculate the object size incorrectly.
 559   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 560 
 561   // We will set up the first region as "starts humongous". This
 562   // will also update the BOT covering all the regions to reflect
 563   // that there is a single object that starts at the bottom of the
 564   // first region.
 565   first_hr->set_starts_humongous(new_top, new_end);
 566   first_hr->set_allocation_context(context);
 567   // Then, if there are any, we will set up the "continues
 568   // humongous" regions.
 569   HeapRegion* hr = NULL;
 570   for (uint i = first + 1; i < last; ++i) {
 571     hr = region_at(i);
 572     hr->set_continues_humongous(first_hr);
 573     hr->set_allocation_context(context);
 574   }
 575   // If we have "continues humongous" regions (hr != NULL), then the
 576   // end of the last one should match new_end.
 577   assert(hr == NULL || hr->end() == new_end, "sanity");
 578 
 579   // Up to this point no concurrent thread would have been able to
 580   // do any scanning on any region in this series. All the top
 581   // fields still point to bottom, so the intersection between
 582   // [bottom,top] and [card_start,card_end] will be empty. Before we
 583   // update the top fields, we'll do a storestore to make sure that
 584   // no thread sees the update to top before the zeroing of the
 585   // object header and the BOT initialization.
 586   OrderAccess::storestore();
 587 
 588   // Now that the BOT and the object header have been initialized,
 589   // we can update top of the "starts humongous" region.
 590   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 591          "new_top should be in this region");
 592   first_hr->set_top(new_top);
 593   if (_hr_printer.is_active()) {
 594     HeapWord* bottom = first_hr->bottom();
 595     HeapWord* end = first_hr->orig_end();
 596     if ((first + 1) == last) {
 597       // the series has a single humongous region
 598       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 599     } else {
 600       // the series has more than one humongous regions
 601       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 602     }
 603   }
 604 
 605   // Now, we will update the top fields of the "continues humongous"
 606   // regions. The reason we need to do this is that, otherwise,
 607   // these regions would look empty and this will confuse parts of
 608   // G1. For example, the code that looks for a consecutive number
 609   // of empty regions will consider them empty and try to
 610   // re-allocate them. We can extend is_empty() to also include
 611   // !is_continues_humongous(), but it is easier to just update the top
 612   // fields here. The way we set top for all regions (i.e., top ==
 613   // end for all regions but the last one, top == new_top for the
 614   // last one) is actually used when we will free up the humongous
 615   // region in free_humongous_region().
 616   hr = NULL;
 617   for (uint i = first + 1; i < last; ++i) {
 618     hr = region_at(i);
 619     if ((i + 1) == last) {
 620       // last continues humongous region
 621       assert(hr->bottom() < new_top && new_top <= hr->end(),
 622              "new_top should fall on this region");
 623       hr->set_top(new_top);
 624       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 625     } else {
 626       // not last one
 627       assert(new_top > hr->end(), "new_top should be above this region");
 628       hr->set_top(hr->end());
 629       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 630     }
 631   }
 632   // If we have continues humongous regions (hr != NULL), then the
 633   // end of the last one should match new_end and its top should
 634   // match new_top.
 635   assert(hr == NULL ||
 636          (hr->end() == new_end && hr->top() == new_top), "sanity");
 637   check_bitmaps("Humongous Region Allocation", first_hr);
 638 
 639   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 640   _allocator->increase_used(first_hr->used());
 641   _humongous_set.add(first_hr);
 642 
 643   return new_obj;
 644 }
 645 
 646 // If could fit into free regions w/o expansion, try.
 647 // Otherwise, if can expand, do so.
 648 // Otherwise, if using ex regions might help, try with ex given back.
 649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 650   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 651 
 652   verify_region_sets_optional();
 653 
 654   uint first = G1_NO_HRM_INDEX;
 655   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 656 
 657   if (obj_regions == 1) {
 658     // Only one region to allocate, try to use a fast path by directly allocating
 659     // from the free lists. Do not try to expand here, we will potentially do that
 660     // later.
 661     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 662     if (hr != NULL) {
 663       first = hr->hrm_index();
 664     }
 665   } else {
 666     // We can't allocate humongous regions spanning more than one region while
 667     // cleanupComplete() is running, since some of the regions we find to be
 668     // empty might not yet be added to the free list. It is not straightforward
 669     // to know in which list they are on so that we can remove them. We only
 670     // need to do this if we need to allocate more than one region to satisfy the
 671     // current humongous allocation request. If we are only allocating one region
 672     // we use the one-region region allocation code (see above), that already
 673     // potentially waits for regions from the secondary free list.
 674     wait_while_free_regions_coming();
 675     append_secondary_free_list_if_not_empty_with_lock();
 676 
 677     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 678     // are lucky enough to find some.
 679     first = _hrm.find_contiguous_only_empty(obj_regions);
 680     if (first != G1_NO_HRM_INDEX) {
 681       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 682     }
 683   }
 684 
 685   if (first == G1_NO_HRM_INDEX) {
 686     // Policy: We could not find enough regions for the humongous object in the
 687     // free list. Look through the heap to find a mix of free and uncommitted regions.
 688     // If so, try expansion.
 689     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 690     if (first != G1_NO_HRM_INDEX) {
 691       // We found something. Make sure these regions are committed, i.e. expand
 692       // the heap. Alternatively we could do a defragmentation GC.
 693       ergo_verbose1(ErgoHeapSizing,
 694                     "attempt heap expansion",
 695                     ergo_format_reason("humongous allocation request failed")
 696                     ergo_format_byte("allocation request"),
 697                     word_size * HeapWordSize);
 698 
 699       _hrm.expand_at(first, obj_regions);
 700       g1_policy()->record_new_heap_size(num_regions());
 701 
 702 #ifdef ASSERT
 703       for (uint i = first; i < first + obj_regions; ++i) {
 704         HeapRegion* hr = region_at(i);
 705         assert(hr->is_free(), "sanity");
 706         assert(hr->is_empty(), "sanity");
 707         assert(is_on_master_free_list(hr), "sanity");
 708       }
 709 #endif
 710       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 711     } else {
 712       // Policy: Potentially trigger a defragmentation GC.
 713     }
 714   }
 715 
 716   HeapWord* result = NULL;
 717   if (first != G1_NO_HRM_INDEX) {
 718     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 719                                                        word_size, context);
 720     assert(result != NULL, "it should always return a valid result");
 721 
 722     // A successful humongous object allocation changes the used space
 723     // information of the old generation so we need to recalculate the
 724     // sizes and update the jstat counters here.
 725     g1mm()->update_sizes();
 726   }
 727 
 728   verify_region_sets_optional();
 729 
 730   return result;
 731 }
 732 
 733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 734   assert_heap_not_locked_and_not_at_safepoint();
 735   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 736 
 737   uint dummy_gc_count_before;
 738   uint dummy_gclocker_retry_count = 0;
 739   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 740 }
 741 
 742 HeapWord*
 743 G1CollectedHeap::mem_allocate(size_t word_size,
 744                               bool*  gc_overhead_limit_was_exceeded) {
 745   assert_heap_not_locked_and_not_at_safepoint();
 746 
 747   // Loop until the allocation is satisfied, or unsatisfied after GC.
 748   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 749     uint gc_count_before;
 750 
 751     HeapWord* result = NULL;
 752     if (!is_humongous(word_size)) {
 753       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 754     } else {
 755       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 756     }
 757     if (result != NULL) {
 758       return result;
 759     }
 760 
 761     // Create the garbage collection operation...
 762     VM_G1CollectForAllocation op(gc_count_before, word_size);
 763     op.set_allocation_context(AllocationContext::current());
 764 
 765     // ...and get the VM thread to execute it.
 766     VMThread::execute(&op);
 767 
 768     if (op.prologue_succeeded() && op.pause_succeeded()) {
 769       // If the operation was successful we'll return the result even
 770       // if it is NULL. If the allocation attempt failed immediately
 771       // after a Full GC, it's unlikely we'll be able to allocate now.
 772       HeapWord* result = op.result();
 773       if (result != NULL && !is_humongous(word_size)) {
 774         // Allocations that take place on VM operations do not do any
 775         // card dirtying and we have to do it here. We only have to do
 776         // this for non-humongous allocations, though.
 777         dirty_young_block(result, word_size);
 778       }
 779       return result;
 780     } else {
 781       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 782         return NULL;
 783       }
 784       assert(op.result() == NULL,
 785              "the result should be NULL if the VM op did not succeed");
 786     }
 787 
 788     // Give a warning if we seem to be looping forever.
 789     if ((QueuedAllocationWarningCount > 0) &&
 790         (try_count % QueuedAllocationWarningCount == 0)) {
 791       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 792     }
 793   }
 794 
 795   ShouldNotReachHere();
 796   return NULL;
 797 }
 798 
 799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 800                                                    AllocationContext_t context,
 801                                                    uint* gc_count_before_ret,
 802                                                    uint* gclocker_retry_count_ret) {
 803   // Make sure you read the note in attempt_allocation_humongous().
 804 
 805   assert_heap_not_locked_and_not_at_safepoint();
 806   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 807          "be called for humongous allocation requests");
 808 
 809   // We should only get here after the first-level allocation attempt
 810   // (attempt_allocation()) failed to allocate.
 811 
 812   // We will loop until a) we manage to successfully perform the
 813   // allocation or b) we successfully schedule a collection which
 814   // fails to perform the allocation. b) is the only case when we'll
 815   // return NULL.
 816   HeapWord* result = NULL;
 817   for (int try_count = 1; /* we'll return */; try_count += 1) {
 818     bool should_try_gc;
 819     uint gc_count_before;
 820 
 821     {
 822       MutexLockerEx x(Heap_lock);
 823       result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
 824                                                                                     false /* bot_updates */);
 825       if (result != NULL) {
 826         return result;
 827       }
 828 
 829       // If we reach here, attempt_allocation_locked() above failed to
 830       // allocate a new region. So the mutator alloc region should be NULL.
 831       assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
 832 
 833       if (GC_locker::is_active_and_needs_gc()) {
 834         if (g1_policy()->can_expand_young_list()) {
 835           // No need for an ergo verbose message here,
 836           // can_expand_young_list() does this when it returns true.
 837           result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
 838                                                                                        false /* bot_updates */);
 839           if (result != NULL) {
 840             return result;
 841           }
 842         }
 843         should_try_gc = false;
 844       } else {
 845         // The GCLocker may not be active but the GCLocker initiated
 846         // GC may not yet have been performed (GCLocker::needs_gc()
 847         // returns true). In this case we do not try this GC and
 848         // wait until the GCLocker initiated GC is performed, and
 849         // then retry the allocation.
 850         if (GC_locker::needs_gc()) {
 851           should_try_gc = false;
 852         } else {
 853           // Read the GC count while still holding the Heap_lock.
 854           gc_count_before = total_collections();
 855           should_try_gc = true;
 856         }
 857       }
 858     }
 859 
 860     if (should_try_gc) {
 861       bool succeeded;
 862       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 863                                    GCCause::_g1_inc_collection_pause);
 864       if (result != NULL) {
 865         assert(succeeded, "only way to get back a non-NULL result");
 866         return result;
 867       }
 868 
 869       if (succeeded) {
 870         // If we get here we successfully scheduled a collection which
 871         // failed to allocate. No point in trying to allocate
 872         // further. We'll just return NULL.
 873         MutexLockerEx x(Heap_lock);
 874         *gc_count_before_ret = total_collections();
 875         return NULL;
 876       }
 877     } else {
 878       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 879         MutexLockerEx x(Heap_lock);
 880         *gc_count_before_ret = total_collections();
 881         return NULL;
 882       }
 883       // The GCLocker is either active or the GCLocker initiated
 884       // GC has not yet been performed. Stall until it is and
 885       // then retry the allocation.
 886       GC_locker::stall_until_clear();
 887       (*gclocker_retry_count_ret) += 1;
 888     }
 889 
 890     // We can reach here if we were unsuccessful in scheduling a
 891     // collection (because another thread beat us to it) or if we were
 892     // stalled due to the GC locker. In either can we should retry the
 893     // allocation attempt in case another thread successfully
 894     // performed a collection and reclaimed enough space. We do the
 895     // first attempt (without holding the Heap_lock) here and the
 896     // follow-on attempt will be at the start of the next loop
 897     // iteration (after taking the Heap_lock).
 898     result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
 899                                                                            false /* bot_updates */);
 900     if (result != NULL) {
 901       return result;
 902     }
 903 
 904     // Give a warning if we seem to be looping forever.
 905     if ((QueuedAllocationWarningCount > 0) &&
 906         (try_count % QueuedAllocationWarningCount == 0)) {
 907       warning("G1CollectedHeap::attempt_allocation_slow() "
 908               "retries %d times", try_count);
 909     }
 910   }
 911 
 912   ShouldNotReachHere();
 913   return NULL;
 914 }
 915 
 916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 917                                                         uint* gc_count_before_ret,
 918                                                         uint* gclocker_retry_count_ret) {
 919   // The structure of this method has a lot of similarities to
 920   // attempt_allocation_slow(). The reason these two were not merged
 921   // into a single one is that such a method would require several "if
 922   // allocation is not humongous do this, otherwise do that"
 923   // conditional paths which would obscure its flow. In fact, an early
 924   // version of this code did use a unified method which was harder to
 925   // follow and, as a result, it had subtle bugs that were hard to
 926   // track down. So keeping these two methods separate allows each to
 927   // be more readable. It will be good to keep these two in sync as
 928   // much as possible.
 929 
 930   assert_heap_not_locked_and_not_at_safepoint();
 931   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 932          "should only be called for humongous allocations");
 933 
 934   // Humongous objects can exhaust the heap quickly, so we should check if we
 935   // need to start a marking cycle at each humongous object allocation. We do
 936   // the check before we do the actual allocation. The reason for doing it
 937   // before the allocation is that we avoid having to keep track of the newly
 938   // allocated memory while we do a GC.
 939   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 940                                            word_size)) {
 941     collect(GCCause::_g1_humongous_allocation);
 942   }
 943 
 944   // We will loop until a) we manage to successfully perform the
 945   // allocation or b) we successfully schedule a collection which
 946   // fails to perform the allocation. b) is the only case when we'll
 947   // return NULL.
 948   HeapWord* result = NULL;
 949   for (int try_count = 1; /* we'll return */; try_count += 1) {
 950     bool should_try_gc;
 951     uint gc_count_before;
 952 
 953     {
 954       MutexLockerEx x(Heap_lock);
 955 
 956       // Given that humongous objects are not allocated in young
 957       // regions, we'll first try to do the allocation without doing a
 958       // collection hoping that there's enough space in the heap.
 959       result = humongous_obj_allocate(word_size, AllocationContext::current());
 960       if (result != NULL) {
 961         return result;
 962       }
 963 
 964       if (GC_locker::is_active_and_needs_gc()) {
 965         should_try_gc = false;
 966       } else {
 967          // The GCLocker may not be active but the GCLocker initiated
 968         // GC may not yet have been performed (GCLocker::needs_gc()
 969         // returns true). In this case we do not try this GC and
 970         // wait until the GCLocker initiated GC is performed, and
 971         // then retry the allocation.
 972         if (GC_locker::needs_gc()) {
 973           should_try_gc = false;
 974         } else {
 975           // Read the GC count while still holding the Heap_lock.
 976           gc_count_before = total_collections();
 977           should_try_gc = true;
 978         }
 979       }
 980     }
 981 
 982     if (should_try_gc) {
 983       // If we failed to allocate the humongous object, we should try to
 984       // do a collection pause (if we're allowed) in case it reclaims
 985       // enough space for the allocation to succeed after the pause.
 986 
 987       bool succeeded;
 988       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 989                                    GCCause::_g1_humongous_allocation);
 990       if (result != NULL) {
 991         assert(succeeded, "only way to get back a non-NULL result");
 992         return result;
 993       }
 994 
 995       if (succeeded) {
 996         // If we get here we successfully scheduled a collection which
 997         // failed to allocate. No point in trying to allocate
 998         // further. We'll just return NULL.
 999         MutexLockerEx x(Heap_lock);
1000         *gc_count_before_ret = total_collections();
1001         return NULL;
1002       }
1003     } else {
1004       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1005         MutexLockerEx x(Heap_lock);
1006         *gc_count_before_ret = total_collections();
1007         return NULL;
1008       }
1009       // The GCLocker is either active or the GCLocker initiated
1010       // GC has not yet been performed. Stall until it is and
1011       // then retry the allocation.
1012       GC_locker::stall_until_clear();
1013       (*gclocker_retry_count_ret) += 1;
1014     }
1015 
1016     // We can reach here if we were unsuccessful in scheduling a
1017     // collection (because another thread beat us to it) or if we were
1018     // stalled due to the GC locker. In either can we should retry the
1019     // allocation attempt in case another thread successfully
1020     // performed a collection and reclaimed enough space.  Give a
1021     // warning if we seem to be looping forever.
1022 
1023     if ((QueuedAllocationWarningCount > 0) &&
1024         (try_count % QueuedAllocationWarningCount == 0)) {
1025       warning("G1CollectedHeap::attempt_allocation_humongous() "
1026               "retries %d times", try_count);
1027     }
1028   }
1029 
1030   ShouldNotReachHere();
1031   return NULL;
1032 }
1033 
1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1035                                                            AllocationContext_t context,
1036                                                            bool expect_null_mutator_alloc_region) {
1037   assert_at_safepoint(true /* should_be_vm_thread */);
1038   assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1039                                              !expect_null_mutator_alloc_region,
1040          "the current alloc region was unexpectedly found to be non-NULL");
1041 
1042   if (!is_humongous(word_size)) {
1043     return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1044                                                       false /* bot_updates */);
1045   } else {
1046     HeapWord* result = humongous_obj_allocate(word_size, context);
1047     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1048       g1_policy()->set_initiate_conc_mark_if_possible();
1049     }
1050     return result;
1051   }
1052 
1053   ShouldNotReachHere();
1054 }
1055 
1056 class PostMCRemSetClearClosure: public HeapRegionClosure {
1057   G1CollectedHeap* _g1h;
1058   ModRefBarrierSet* _mr_bs;
1059 public:
1060   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1061     _g1h(g1h), _mr_bs(mr_bs) {}
1062 
1063   bool doHeapRegion(HeapRegion* r) {
1064     HeapRegionRemSet* hrrs = r->rem_set();
1065 
1066     if (r->is_continues_humongous()) {
1067       // We'll assert that the strong code root list and RSet is empty
1068       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1069       assert(hrrs->occupied() == 0, "RSet should be empty");
1070       return false;
1071     }
1072 
1073     _g1h->reset_gc_time_stamps(r);
1074     hrrs->clear();
1075     // You might think here that we could clear just the cards
1076     // corresponding to the used region.  But no: if we leave a dirty card
1077     // in a region we might allocate into, then it would prevent that card
1078     // from being enqueued, and cause it to be missed.
1079     // Re: the performance cost: we shouldn't be doing full GC anyway!
1080     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1081 
1082     return false;
1083   }
1084 };
1085 
1086 void G1CollectedHeap::clear_rsets_post_compaction() {
1087   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1088   heap_region_iterate(&rs_clear);
1089 }
1090 
1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1092   G1CollectedHeap*   _g1h;
1093   UpdateRSOopClosure _cl;
1094   int                _worker_i;
1095 public:
1096   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1097     _cl(g1->g1_rem_set(), worker_i),
1098     _worker_i(worker_i),
1099     _g1h(g1)
1100   { }
1101 
1102   bool doHeapRegion(HeapRegion* r) {
1103     if (!r->is_continues_humongous()) {
1104       _cl.set_from(r);
1105       r->oop_iterate(&_cl);
1106     }
1107     return false;
1108   }
1109 };
1110 
1111 class ParRebuildRSTask: public AbstractGangTask {
1112   G1CollectedHeap* _g1;
1113   HeapRegionClaimer _hrclaimer;
1114 
1115 public:
1116   ParRebuildRSTask(G1CollectedHeap* g1) :
1117       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1118 
1119   void work(uint worker_id) {
1120     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1121     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1122   }
1123 };
1124 
1125 class PostCompactionPrinterClosure: public HeapRegionClosure {
1126 private:
1127   G1HRPrinter* _hr_printer;
1128 public:
1129   bool doHeapRegion(HeapRegion* hr) {
1130     assert(!hr->is_young(), "not expecting to find young regions");
1131     if (hr->is_free()) {
1132       // We only generate output for non-empty regions.
1133     } else if (hr->is_starts_humongous()) {
1134       if (hr->region_num() == 1) {
1135         // single humongous region
1136         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1137       } else {
1138         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1139       }
1140     } else if (hr->is_continues_humongous()) {
1141       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1142     } else if (hr->is_old()) {
1143       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1144     } else {
1145       ShouldNotReachHere();
1146     }
1147     return false;
1148   }
1149 
1150   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1151     : _hr_printer(hr_printer) { }
1152 };
1153 
1154 void G1CollectedHeap::print_hrm_post_compaction() {
1155   PostCompactionPrinterClosure cl(hr_printer());
1156   heap_region_iterate(&cl);
1157 }
1158 
1159 bool G1CollectedHeap::do_collection(bool explicit_gc,
1160                                     bool clear_all_soft_refs,
1161                                     size_t word_size) {
1162   assert_at_safepoint(true /* should_be_vm_thread */);
1163 
1164   if (GC_locker::check_active_before_gc()) {
1165     return false;
1166   }
1167 
1168   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1169   gc_timer->register_gc_start();
1170 
1171   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1172   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1173 
1174   SvcGCMarker sgcm(SvcGCMarker::FULL);
1175   ResourceMark rm;
1176 
1177   print_heap_before_gc();
1178   trace_heap_before_gc(gc_tracer);
1179 
1180   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1181 
1182   verify_region_sets_optional();
1183 
1184   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1185                            collector_policy()->should_clear_all_soft_refs();
1186 
1187   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1188 
1189   {
1190     IsGCActiveMark x;
1191 
1192     // Timing
1193     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1194     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1195 
1196     {
1197       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1198       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1199       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1200 
1201       g1_policy()->record_full_collection_start();
1202 
1203       // Note: When we have a more flexible GC logging framework that
1204       // allows us to add optional attributes to a GC log record we
1205       // could consider timing and reporting how long we wait in the
1206       // following two methods.
1207       wait_while_free_regions_coming();
1208       // If we start the compaction before the CM threads finish
1209       // scanning the root regions we might trip them over as we'll
1210       // be moving objects / updating references. So let's wait until
1211       // they are done. By telling them to abort, they should complete
1212       // early.
1213       _cm->root_regions()->abort();
1214       _cm->root_regions()->wait_until_scan_finished();
1215       append_secondary_free_list_if_not_empty_with_lock();
1216 
1217       gc_prologue(true);
1218       increment_total_collections(true /* full gc */);
1219       increment_old_marking_cycles_started();
1220 
1221       assert(used() == recalculate_used(), "Should be equal");
1222 
1223       verify_before_gc();
1224 
1225       check_bitmaps("Full GC Start");
1226       pre_full_gc_dump(gc_timer);
1227 
1228       COMPILER2_PRESENT(DerivedPointerTable::clear());
1229 
1230       // Disable discovery and empty the discovered lists
1231       // for the CM ref processor.
1232       ref_processor_cm()->disable_discovery();
1233       ref_processor_cm()->abandon_partial_discovery();
1234       ref_processor_cm()->verify_no_references_recorded();
1235 
1236       // Abandon current iterations of concurrent marking and concurrent
1237       // refinement, if any are in progress. We have to do this before
1238       // wait_until_scan_finished() below.
1239       concurrent_mark()->abort();
1240 
1241       // Make sure we'll choose a new allocation region afterwards.
1242       _allocator->release_mutator_alloc_region();
1243       _allocator->abandon_gc_alloc_regions();
1244       g1_rem_set()->cleanupHRRS();
1245 
1246       // We should call this after we retire any currently active alloc
1247       // regions so that all the ALLOC / RETIRE events are generated
1248       // before the start GC event.
1249       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1250 
1251       // We may have added regions to the current incremental collection
1252       // set between the last GC or pause and now. We need to clear the
1253       // incremental collection set and then start rebuilding it afresh
1254       // after this full GC.
1255       abandon_collection_set(g1_policy()->inc_cset_head());
1256       g1_policy()->clear_incremental_cset();
1257       g1_policy()->stop_incremental_cset_building();
1258 
1259       tear_down_region_sets(false /* free_list_only */);
1260       g1_policy()->set_gcs_are_young(true);
1261 
1262       // See the comments in g1CollectedHeap.hpp and
1263       // G1CollectedHeap::ref_processing_init() about
1264       // how reference processing currently works in G1.
1265 
1266       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1267       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1268 
1269       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1270       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1271 
1272       ref_processor_stw()->enable_discovery();
1273       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1274 
1275       // Do collection work
1276       {
1277         HandleMark hm;  // Discard invalid handles created during gc
1278         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1279       }
1280 
1281       assert(num_free_regions() == 0, "we should not have added any free regions");
1282       rebuild_region_sets(false /* free_list_only */);
1283 
1284       // Enqueue any discovered reference objects that have
1285       // not been removed from the discovered lists.
1286       ref_processor_stw()->enqueue_discovered_references();
1287 
1288       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1289 
1290       MemoryService::track_memory_usage();
1291 
1292       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1293       ref_processor_stw()->verify_no_references_recorded();
1294 
1295       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1296       ClassLoaderDataGraph::purge();
1297       MetaspaceAux::verify_metrics();
1298 
1299       // Note: since we've just done a full GC, concurrent
1300       // marking is no longer active. Therefore we need not
1301       // re-enable reference discovery for the CM ref processor.
1302       // That will be done at the start of the next marking cycle.
1303       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1304       ref_processor_cm()->verify_no_references_recorded();
1305 
1306       reset_gc_time_stamp();
1307       // Since everything potentially moved, we will clear all remembered
1308       // sets, and clear all cards.  Later we will rebuild remembered
1309       // sets. We will also reset the GC time stamps of the regions.
1310       clear_rsets_post_compaction();
1311       check_gc_time_stamps();
1312 
1313       // Resize the heap if necessary.
1314       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1315 
1316       if (_hr_printer.is_active()) {
1317         // We should do this after we potentially resize the heap so
1318         // that all the COMMIT / UNCOMMIT events are generated before
1319         // the end GC event.
1320 
1321         print_hrm_post_compaction();
1322         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1323       }
1324 
1325       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1326       if (hot_card_cache->use_cache()) {
1327         hot_card_cache->reset_card_counts();
1328         hot_card_cache->reset_hot_cache();
1329       }
1330 
1331       // Rebuild remembered sets of all regions.
1332       uint n_workers =
1333         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1334                                                 workers()->active_workers(),
1335                                                 Threads::number_of_non_daemon_threads());
1336       assert(UseDynamicNumberOfGCThreads ||
1337              n_workers == workers()->total_workers(),
1338              "If not dynamic should be using all the  workers");
1339       workers()->set_active_workers(n_workers);
1340       // Set parallel threads in the heap (_n_par_threads) only
1341       // before a parallel phase and always reset it to 0 after
1342       // the phase so that the number of parallel threads does
1343       // no get carried forward to a serial phase where there
1344       // may be code that is "possibly_parallel".
1345       set_par_threads(n_workers);
1346 
1347       ParRebuildRSTask rebuild_rs_task(this);
1348       assert(UseDynamicNumberOfGCThreads ||
1349              workers()->active_workers() == workers()->total_workers(),
1350              "Unless dynamic should use total workers");
1351       // Use the most recent number of  active workers
1352       assert(workers()->active_workers() > 0,
1353              "Active workers not properly set");
1354       set_par_threads(workers()->active_workers());
1355       workers()->run_task(&rebuild_rs_task);
1356       set_par_threads(0);
1357 
1358       // Rebuild the strong code root lists for each region
1359       rebuild_strong_code_roots();
1360 
1361       if (true) { // FIXME
1362         MetaspaceGC::compute_new_size();
1363       }
1364 
1365 #ifdef TRACESPINNING
1366       ParallelTaskTerminator::print_termination_counts();
1367 #endif
1368 
1369       // Discard all rset updates
1370       JavaThread::dirty_card_queue_set().abandon_logs();
1371       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1372 
1373       _young_list->reset_sampled_info();
1374       // At this point there should be no regions in the
1375       // entire heap tagged as young.
1376       assert(check_young_list_empty(true /* check_heap */),
1377              "young list should be empty at this point");
1378 
1379       // Update the number of full collections that have been completed.
1380       increment_old_marking_cycles_completed(false /* concurrent */);
1381 
1382       _hrm.verify_optional();
1383       verify_region_sets_optional();
1384 
1385       verify_after_gc();
1386 
1387       // Clear the previous marking bitmap, if needed for bitmap verification.
1388       // Note we cannot do this when we clear the next marking bitmap in
1389       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1390       // objects marked during a full GC against the previous bitmap.
1391       // But we need to clear it before calling check_bitmaps below since
1392       // the full GC has compacted objects and updated TAMS but not updated
1393       // the prev bitmap.
1394       if (G1VerifyBitmaps) {
1395         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1396       }
1397       check_bitmaps("Full GC End");
1398 
1399       // Start a new incremental collection set for the next pause
1400       assert(g1_policy()->collection_set() == NULL, "must be");
1401       g1_policy()->start_incremental_cset_building();
1402 
1403       clear_cset_fast_test();
1404 
1405       _allocator->init_mutator_alloc_region();
1406 
1407       g1_policy()->record_full_collection_end();
1408 
1409       if (G1Log::fine()) {
1410         g1_policy()->print_heap_transition();
1411       }
1412 
1413       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1414       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1415       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1416       // before any GC notifications are raised.
1417       g1mm()->update_sizes();
1418 
1419       gc_epilogue(true);
1420     }
1421 
1422     if (G1Log::finer()) {
1423       g1_policy()->print_detailed_heap_transition(true /* full */);
1424     }
1425 
1426     print_heap_after_gc();
1427     trace_heap_after_gc(gc_tracer);
1428 
1429     post_full_gc_dump(gc_timer);
1430 
1431     gc_timer->register_gc_end();
1432     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1433   }
1434 
1435   return true;
1436 }
1437 
1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1439   // do_collection() will return whether it succeeded in performing
1440   // the GC. Currently, there is no facility on the
1441   // do_full_collection() API to notify the caller than the collection
1442   // did not succeed (e.g., because it was locked out by the GC
1443   // locker). So, right now, we'll ignore the return value.
1444   bool dummy = do_collection(true,                /* explicit_gc */
1445                              clear_all_soft_refs,
1446                              0                    /* word_size */);
1447 }
1448 
1449 // This code is mostly copied from TenuredGeneration.
1450 void
1451 G1CollectedHeap::
1452 resize_if_necessary_after_full_collection(size_t word_size) {
1453   // Include the current allocation, if any, and bytes that will be
1454   // pre-allocated to support collections, as "used".
1455   const size_t used_after_gc = used();
1456   const size_t capacity_after_gc = capacity();
1457   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1458 
1459   // This is enforced in arguments.cpp.
1460   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1461          "otherwise the code below doesn't make sense");
1462 
1463   // We don't have floating point command-line arguments
1464   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1465   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1466   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1467   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1468 
1469   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1470   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1471 
1472   // We have to be careful here as these two calculations can overflow
1473   // 32-bit size_t's.
1474   double used_after_gc_d = (double) used_after_gc;
1475   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1476   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1477 
1478   // Let's make sure that they are both under the max heap size, which
1479   // by default will make them fit into a size_t.
1480   double desired_capacity_upper_bound = (double) max_heap_size;
1481   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1482                                     desired_capacity_upper_bound);
1483   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1484                                     desired_capacity_upper_bound);
1485 
1486   // We can now safely turn them into size_t's.
1487   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1488   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1489 
1490   // This assert only makes sense here, before we adjust them
1491   // with respect to the min and max heap size.
1492   assert(minimum_desired_capacity <= maximum_desired_capacity,
1493          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1494                  "maximum_desired_capacity = "SIZE_FORMAT,
1495                  minimum_desired_capacity, maximum_desired_capacity));
1496 
1497   // Should not be greater than the heap max size. No need to adjust
1498   // it with respect to the heap min size as it's a lower bound (i.e.,
1499   // we'll try to make the capacity larger than it, not smaller).
1500   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1501   // Should not be less than the heap min size. No need to adjust it
1502   // with respect to the heap max size as it's an upper bound (i.e.,
1503   // we'll try to make the capacity smaller than it, not greater).
1504   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1505 
1506   if (capacity_after_gc < minimum_desired_capacity) {
1507     // Don't expand unless it's significant
1508     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1509     ergo_verbose4(ErgoHeapSizing,
1510                   "attempt heap expansion",
1511                   ergo_format_reason("capacity lower than "
1512                                      "min desired capacity after Full GC")
1513                   ergo_format_byte("capacity")
1514                   ergo_format_byte("occupancy")
1515                   ergo_format_byte_perc("min desired capacity"),
1516                   capacity_after_gc, used_after_gc,
1517                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1518     expand(expand_bytes);
1519 
1520     // No expansion, now see if we want to shrink
1521   } else if (capacity_after_gc > maximum_desired_capacity) {
1522     // Capacity too large, compute shrinking size
1523     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1524     ergo_verbose4(ErgoHeapSizing,
1525                   "attempt heap shrinking",
1526                   ergo_format_reason("capacity higher than "
1527                                      "max desired capacity after Full GC")
1528                   ergo_format_byte("capacity")
1529                   ergo_format_byte("occupancy")
1530                   ergo_format_byte_perc("max desired capacity"),
1531                   capacity_after_gc, used_after_gc,
1532                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1533     shrink(shrink_bytes);
1534   }
1535 }
1536 
1537 
1538 HeapWord*
1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1540                                            AllocationContext_t context,
1541                                            bool* succeeded) {
1542   assert_at_safepoint(true /* should_be_vm_thread */);
1543 
1544   *succeeded = true;
1545   // Let's attempt the allocation first.
1546   HeapWord* result =
1547     attempt_allocation_at_safepoint(word_size,
1548                                     context,
1549                                     false /* expect_null_mutator_alloc_region */);
1550   if (result != NULL) {
1551     assert(*succeeded, "sanity");
1552     return result;
1553   }
1554 
1555   // In a G1 heap, we're supposed to keep allocation from failing by
1556   // incremental pauses.  Therefore, at least for now, we'll favor
1557   // expansion over collection.  (This might change in the future if we can
1558   // do something smarter than full collection to satisfy a failed alloc.)
1559   result = expand_and_allocate(word_size, context);
1560   if (result != NULL) {
1561     assert(*succeeded, "sanity");
1562     return result;
1563   }
1564 
1565   // Expansion didn't work, we'll try to do a Full GC.
1566   bool gc_succeeded = do_collection(false, /* explicit_gc */
1567                                     false, /* clear_all_soft_refs */
1568                                     word_size);
1569   if (!gc_succeeded) {
1570     *succeeded = false;
1571     return NULL;
1572   }
1573 
1574   // Retry the allocation
1575   result = attempt_allocation_at_safepoint(word_size,
1576                                            context,
1577                                            true /* expect_null_mutator_alloc_region */);
1578   if (result != NULL) {
1579     assert(*succeeded, "sanity");
1580     return result;
1581   }
1582 
1583   // Then, try a Full GC that will collect all soft references.
1584   gc_succeeded = do_collection(false, /* explicit_gc */
1585                                true,  /* clear_all_soft_refs */
1586                                word_size);
1587   if (!gc_succeeded) {
1588     *succeeded = false;
1589     return NULL;
1590   }
1591 
1592   // Retry the allocation once more
1593   result = attempt_allocation_at_safepoint(word_size,
1594                                            context,
1595                                            true /* expect_null_mutator_alloc_region */);
1596   if (result != NULL) {
1597     assert(*succeeded, "sanity");
1598     return result;
1599   }
1600 
1601   assert(!collector_policy()->should_clear_all_soft_refs(),
1602          "Flag should have been handled and cleared prior to this point");
1603 
1604   // What else?  We might try synchronous finalization later.  If the total
1605   // space available is large enough for the allocation, then a more
1606   // complete compaction phase than we've tried so far might be
1607   // appropriate.
1608   assert(*succeeded, "sanity");
1609   return NULL;
1610 }
1611 
1612 // Attempting to expand the heap sufficiently
1613 // to support an allocation of the given "word_size".  If
1614 // successful, perform the allocation and return the address of the
1615 // allocated block, or else "NULL".
1616 
1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1618   assert_at_safepoint(true /* should_be_vm_thread */);
1619 
1620   verify_region_sets_optional();
1621 
1622   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1623   ergo_verbose1(ErgoHeapSizing,
1624                 "attempt heap expansion",
1625                 ergo_format_reason("allocation request failed")
1626                 ergo_format_byte("allocation request"),
1627                 word_size * HeapWordSize);
1628   if (expand(expand_bytes)) {
1629     _hrm.verify_optional();
1630     verify_region_sets_optional();
1631     return attempt_allocation_at_safepoint(word_size,
1632                                            context,
1633                                            false /* expect_null_mutator_alloc_region */);
1634   }
1635   return NULL;
1636 }
1637 
1638 bool G1CollectedHeap::expand(size_t expand_bytes) {
1639   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1640   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1641                                        HeapRegion::GrainBytes);
1642   ergo_verbose2(ErgoHeapSizing,
1643                 "expand the heap",
1644                 ergo_format_byte("requested expansion amount")
1645                 ergo_format_byte("attempted expansion amount"),
1646                 expand_bytes, aligned_expand_bytes);
1647 
1648   if (is_maximal_no_gc()) {
1649     ergo_verbose0(ErgoHeapSizing,
1650                       "did not expand the heap",
1651                       ergo_format_reason("heap already fully expanded"));
1652     return false;
1653   }
1654 
1655   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1656   assert(regions_to_expand > 0, "Must expand by at least one region");
1657 
1658   uint expanded_by = _hrm.expand_by(regions_to_expand);
1659 
1660   if (expanded_by > 0) {
1661     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1662     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1663     g1_policy()->record_new_heap_size(num_regions());
1664   } else {
1665     ergo_verbose0(ErgoHeapSizing,
1666                   "did not expand the heap",
1667                   ergo_format_reason("heap expansion operation failed"));
1668     // The expansion of the virtual storage space was unsuccessful.
1669     // Let's see if it was because we ran out of swap.
1670     if (G1ExitOnExpansionFailure &&
1671         _hrm.available() >= regions_to_expand) {
1672       // We had head room...
1673       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1674     }
1675   }
1676   return regions_to_expand > 0;
1677 }
1678 
1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1680   size_t aligned_shrink_bytes =
1681     ReservedSpace::page_align_size_down(shrink_bytes);
1682   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1683                                          HeapRegion::GrainBytes);
1684   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1685 
1686   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1687   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1688 
1689   ergo_verbose3(ErgoHeapSizing,
1690                 "shrink the heap",
1691                 ergo_format_byte("requested shrinking amount")
1692                 ergo_format_byte("aligned shrinking amount")
1693                 ergo_format_byte("attempted shrinking amount"),
1694                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1695   if (num_regions_removed > 0) {
1696     g1_policy()->record_new_heap_size(num_regions());
1697   } else {
1698     ergo_verbose0(ErgoHeapSizing,
1699                   "did not shrink the heap",
1700                   ergo_format_reason("heap shrinking operation failed"));
1701   }
1702 }
1703 
1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705   verify_region_sets_optional();
1706 
1707   // We should only reach here at the end of a Full GC which means we
1708   // should not not be holding to any GC alloc regions. The method
1709   // below will make sure of that and do any remaining clean up.
1710   _allocator->abandon_gc_alloc_regions();
1711 
1712   // Instead of tearing down / rebuilding the free lists here, we
1713   // could instead use the remove_all_pending() method on free_list to
1714   // remove only the ones that we need to remove.
1715   tear_down_region_sets(true /* free_list_only */);
1716   shrink_helper(shrink_bytes);
1717   rebuild_region_sets(true /* free_list_only */);
1718 
1719   _hrm.verify_optional();
1720   verify_region_sets_optional();
1721 }
1722 
1723 // Public methods.
1724 
1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1727 #endif // _MSC_VER
1728 
1729 
1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1731   SharedHeap(),
1732   _g1_policy(policy_),
1733   _dirty_card_queue_set(false),
1734   _into_cset_dirty_card_queue_set(false),
1735   _is_alive_closure_cm(this),
1736   _is_alive_closure_stw(this),
1737   _ref_processor_cm(NULL),
1738   _ref_processor_stw(NULL),
1739   _bot_shared(NULL),
1740   _evac_failure_scan_stack(NULL),
1741   _mark_in_progress(false),
1742   _cg1r(NULL),
1743   _g1mm(NULL),
1744   _refine_cte_cl(NULL),
1745   _full_collection(false),
1746   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1747   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1748   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1749   _humongous_is_live(),
1750   _has_humongous_reclaim_candidates(false),
1751   _free_regions_coming(false),
1752   _young_list(new YoungList(this)),
1753   _gc_time_stamp(0),
1754   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1755   _old_plab_stats(OldPLABSize, PLABWeight),
1756   _expand_heap_after_alloc_failure(true),
1757   _surviving_young_words(NULL),
1758   _old_marking_cycles_started(0),
1759   _old_marking_cycles_completed(0),
1760   _concurrent_cycle_started(false),
1761   _heap_summary_sent(false),
1762   _in_cset_fast_test(),
1763   _dirty_cards_region_list(NULL),
1764   _worker_cset_start_region(NULL),
1765   _worker_cset_start_region_time_stamp(NULL),
1766   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1767   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1768   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1769   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1770 
1771   _g1h = this;
1772 
1773   _allocator = G1Allocator::create_allocator(_g1h);
1774   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1775 
1776   int n_queues = MAX2((int)ParallelGCThreads, 1);
1777   _task_queues = new RefToScanQueueSet(n_queues);
1778 
1779   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1780   assert(n_rem_sets > 0, "Invariant.");
1781 
1782   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1783   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1784   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1785 
1786   for (int i = 0; i < n_queues; i++) {
1787     RefToScanQueue* q = new RefToScanQueue();
1788     q->initialize();
1789     _task_queues->register_queue(i, q);
1790     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1791   }
1792   clear_cset_start_regions();
1793 
1794   // Initialize the G1EvacuationFailureALot counters and flags.
1795   NOT_PRODUCT(reset_evacuation_should_fail();)
1796 
1797   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1798 }
1799 
1800 jint G1CollectedHeap::initialize() {
1801   CollectedHeap::pre_initialize();
1802   os::enable_vtime();
1803 
1804   G1Log::init();
1805 
1806   // Necessary to satisfy locking discipline assertions.
1807 
1808   MutexLocker x(Heap_lock);
1809 
1810   // We have to initialize the printer before committing the heap, as
1811   // it will be used then.
1812   _hr_printer.set_active(G1PrintHeapRegions);
1813 
1814   // While there are no constraints in the GC code that HeapWordSize
1815   // be any particular value, there are multiple other areas in the
1816   // system which believe this to be true (e.g. oop->object_size in some
1817   // cases incorrectly returns the size in wordSize units rather than
1818   // HeapWordSize).
1819   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1820 
1821   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1822   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1823   size_t heap_alignment = collector_policy()->heap_alignment();
1824 
1825   // Ensure that the sizes are properly aligned.
1826   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1827   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1828   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1829 
1830   _refine_cte_cl = new RefineCardTableEntryClosure();
1831 
1832   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1833 
1834   // Reserve the maximum.
1835 
1836   // When compressed oops are enabled, the preferred heap base
1837   // is calculated by subtracting the requested size from the
1838   // 32Gb boundary and using the result as the base address for
1839   // heap reservation. If the requested size is not aligned to
1840   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1841   // into the ReservedHeapSpace constructor) then the actual
1842   // base of the reserved heap may end up differing from the
1843   // address that was requested (i.e. the preferred heap base).
1844   // If this happens then we could end up using a non-optimal
1845   // compressed oops mode.
1846 
1847   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1848                                                  heap_alignment);
1849 
1850   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1851 
1852   // Create the barrier set for the entire reserved region.
1853   G1SATBCardTableLoggingModRefBS* bs
1854     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1855   bs->initialize();
1856   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1857   set_barrier_set(bs);
1858 
1859   // Also create a G1 rem set.
1860   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1861 
1862   // Carve out the G1 part of the heap.
1863 
1864   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1865   G1RegionToSpaceMapper* heap_storage =
1866     G1RegionToSpaceMapper::create_mapper(g1_rs,
1867                                          UseLargePages ? os::large_page_size() : os::vm_page_size(),
1868                                          HeapRegion::GrainBytes,
1869                                          1,
1870                                          mtJavaHeap);
1871   heap_storage->set_mapping_changed_listener(&_listener);
1872 
1873   // Reserve space for the block offset table. We do not support automatic uncommit
1874   // for the card table at this time. BOT only.
1875   ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1876   G1RegionToSpaceMapper* bot_storage =
1877     G1RegionToSpaceMapper::create_mapper(bot_rs,
1878                                          os::vm_page_size(),
1879                                          HeapRegion::GrainBytes,
1880                                          G1BlockOffsetSharedArray::N_bytes,
1881                                          mtGC);
1882 
1883   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1884   G1RegionToSpaceMapper* cardtable_storage =
1885     G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1886                                          os::vm_page_size(),
1887                                          HeapRegion::GrainBytes,
1888                                          G1BlockOffsetSharedArray::N_bytes,
1889                                          mtGC);
1890 
1891   // Reserve space for the card counts table.
1892   ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1893   G1RegionToSpaceMapper* card_counts_storage =
1894     G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1895                                          os::vm_page_size(),
1896                                          HeapRegion::GrainBytes,
1897                                          G1BlockOffsetSharedArray::N_bytes,
1898                                          mtGC);
1899 
1900   // Reserve space for prev and next bitmap.
1901   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1902 
1903   ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1904   G1RegionToSpaceMapper* prev_bitmap_storage =
1905     G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1906                                          os::vm_page_size(),
1907                                          HeapRegion::GrainBytes,
1908                                          CMBitMap::mark_distance(),
1909                                          mtGC);
1910 
1911   ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1912   G1RegionToSpaceMapper* next_bitmap_storage =
1913     G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1914                                          os::vm_page_size(),
1915                                          HeapRegion::GrainBytes,
1916                                          CMBitMap::mark_distance(),
1917                                          mtGC);
1918 
1919   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1920   g1_barrier_set()->initialize(cardtable_storage);
1921    // Do later initialization work for concurrent refinement.
1922   _cg1r->init(card_counts_storage);
1923 
1924   // 6843694 - ensure that the maximum region index can fit
1925   // in the remembered set structures.
1926   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1927   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1928 
1929   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1930   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1931   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1932             "too many cards per region");
1933 
1934   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1935 
1936   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1937 
1938   _g1h = this;
1939 
1940   _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1941   _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1942 
1943   // Create the ConcurrentMark data structure and thread.
1944   // (Must do this late, so that "max_regions" is defined.)
1945   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1946   if (_cm == NULL || !_cm->completed_initialization()) {
1947     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1948     return JNI_ENOMEM;
1949   }
1950   _cmThread = _cm->cmThread();
1951 
1952   // Initialize the from_card cache structure of HeapRegionRemSet.
1953   HeapRegionRemSet::init_heap(max_regions());
1954 
1955   // Now expand into the initial heap size.
1956   if (!expand(init_byte_size)) {
1957     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1958     return JNI_ENOMEM;
1959   }
1960 
1961   // Perform any initialization actions delegated to the policy.
1962   g1_policy()->init();
1963 
1964   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1965                                                SATB_Q_FL_lock,
1966                                                G1SATBProcessCompletedThreshold,
1967                                                Shared_SATB_Q_lock);
1968 
1969   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1970                                                 DirtyCardQ_CBL_mon,
1971                                                 DirtyCardQ_FL_lock,
1972                                                 concurrent_g1_refine()->yellow_zone(),
1973                                                 concurrent_g1_refine()->red_zone(),
1974                                                 Shared_DirtyCardQ_lock);
1975 
1976   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1977                                     DirtyCardQ_CBL_mon,
1978                                     DirtyCardQ_FL_lock,
1979                                     -1, // never trigger processing
1980                                     -1, // no limit on length
1981                                     Shared_DirtyCardQ_lock,
1982                                     &JavaThread::dirty_card_queue_set());
1983 
1984   // Initialize the card queue set used to hold cards containing
1985   // references into the collection set.
1986   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1987                                              DirtyCardQ_CBL_mon,
1988                                              DirtyCardQ_FL_lock,
1989                                              -1, // never trigger processing
1990                                              -1, // no limit on length
1991                                              Shared_DirtyCardQ_lock,
1992                                              &JavaThread::dirty_card_queue_set());
1993 
1994   // Here we allocate the dummy HeapRegion that is required by the
1995   // G1AllocRegion class.
1996   HeapRegion* dummy_region = _hrm.get_dummy_region();
1997 
1998   // We'll re-use the same region whether the alloc region will
1999   // require BOT updates or not and, if it doesn't, then a non-young
2000   // region will complain that it cannot support allocations without
2001   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2002   dummy_region->set_eden();
2003   // Make sure it's full.
2004   dummy_region->set_top(dummy_region->end());
2005   G1AllocRegion::setup(this, dummy_region);
2006 
2007   _allocator->init_mutator_alloc_region();
2008 
2009   // Do create of the monitoring and management support so that
2010   // values in the heap have been properly initialized.
2011   _g1mm = new G1MonitoringSupport(this);
2012 
2013   G1StringDedup::initialize();
2014 
2015   return JNI_OK;
2016 }
2017 
2018 void G1CollectedHeap::stop() {
2019   // Stop all concurrent threads. We do this to make sure these threads
2020   // do not continue to execute and access resources (e.g. gclog_or_tty)
2021   // that are destroyed during shutdown.
2022   _cg1r->stop();
2023   _cmThread->stop();
2024   if (G1StringDedup::is_enabled()) {
2025     G1StringDedup::stop();
2026   }
2027 }
2028 
2029 void G1CollectedHeap::clear_humongous_is_live_table() {
2030   guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2031   _humongous_is_live.clear();
2032 }
2033 
2034 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2035   return HeapRegion::max_region_size();
2036 }
2037 
2038 void G1CollectedHeap::ref_processing_init() {
2039   // Reference processing in G1 currently works as follows:
2040   //
2041   // * There are two reference processor instances. One is
2042   //   used to record and process discovered references
2043   //   during concurrent marking; the other is used to
2044   //   record and process references during STW pauses
2045   //   (both full and incremental).
2046   // * Both ref processors need to 'span' the entire heap as
2047   //   the regions in the collection set may be dotted around.
2048   //
2049   // * For the concurrent marking ref processor:
2050   //   * Reference discovery is enabled at initial marking.
2051   //   * Reference discovery is disabled and the discovered
2052   //     references processed etc during remarking.
2053   //   * Reference discovery is MT (see below).
2054   //   * Reference discovery requires a barrier (see below).
2055   //   * Reference processing may or may not be MT
2056   //     (depending on the value of ParallelRefProcEnabled
2057   //     and ParallelGCThreads).
2058   //   * A full GC disables reference discovery by the CM
2059   //     ref processor and abandons any entries on it's
2060   //     discovered lists.
2061   //
2062   // * For the STW processor:
2063   //   * Non MT discovery is enabled at the start of a full GC.
2064   //   * Processing and enqueueing during a full GC is non-MT.
2065   //   * During a full GC, references are processed after marking.
2066   //
2067   //   * Discovery (may or may not be MT) is enabled at the start
2068   //     of an incremental evacuation pause.
2069   //   * References are processed near the end of a STW evacuation pause.
2070   //   * For both types of GC:
2071   //     * Discovery is atomic - i.e. not concurrent.
2072   //     * Reference discovery will not need a barrier.
2073 
2074   SharedHeap::ref_processing_init();
2075   MemRegion mr = reserved_region();
2076 
2077   // Concurrent Mark ref processor
2078   _ref_processor_cm =
2079     new ReferenceProcessor(mr,    // span
2080                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2081                                 // mt processing
2082                            (int) ParallelGCThreads,
2083                                 // degree of mt processing
2084                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2085                                 // mt discovery
2086                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2087                                 // degree of mt discovery
2088                            false,
2089                                 // Reference discovery is not atomic
2090                            &_is_alive_closure_cm);
2091                                 // is alive closure
2092                                 // (for efficiency/performance)
2093 
2094   // STW ref processor
2095   _ref_processor_stw =
2096     new ReferenceProcessor(mr,    // span
2097                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2098                                 // mt processing
2099                            MAX2((int)ParallelGCThreads, 1),
2100                                 // degree of mt processing
2101                            (ParallelGCThreads > 1),
2102                                 // mt discovery
2103                            MAX2((int)ParallelGCThreads, 1),
2104                                 // degree of mt discovery
2105                            true,
2106                                 // Reference discovery is atomic
2107                            &_is_alive_closure_stw);
2108                                 // is alive closure
2109                                 // (for efficiency/performance)
2110 }
2111 
2112 size_t G1CollectedHeap::capacity() const {
2113   return _hrm.length() * HeapRegion::GrainBytes;
2114 }
2115 
2116 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2117   assert(!hr->is_continues_humongous(), "pre-condition");
2118   hr->reset_gc_time_stamp();
2119   if (hr->is_starts_humongous()) {
2120     uint first_index = hr->hrm_index() + 1;
2121     uint last_index = hr->last_hc_index();
2122     for (uint i = first_index; i < last_index; i += 1) {
2123       HeapRegion* chr = region_at(i);
2124       assert(chr->is_continues_humongous(), "sanity");
2125       chr->reset_gc_time_stamp();
2126     }
2127   }
2128 }
2129 
2130 #ifndef PRODUCT
2131 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2132 private:
2133   unsigned _gc_time_stamp;
2134   bool _failures;
2135 
2136 public:
2137   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2138     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2139 
2140   virtual bool doHeapRegion(HeapRegion* hr) {
2141     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2142     if (_gc_time_stamp != region_gc_time_stamp) {
2143       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2144                              "expected %d", HR_FORMAT_PARAMS(hr),
2145                              region_gc_time_stamp, _gc_time_stamp);
2146       _failures = true;
2147     }
2148     return false;
2149   }
2150 
2151   bool failures() { return _failures; }
2152 };
2153 
2154 void G1CollectedHeap::check_gc_time_stamps() {
2155   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2156   heap_region_iterate(&cl);
2157   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2158 }
2159 #endif // PRODUCT
2160 
2161 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2162                                                  DirtyCardQueue* into_cset_dcq,
2163                                                  bool concurrent,
2164                                                  uint worker_i) {
2165   // Clean cards in the hot card cache
2166   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2167   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2168 
2169   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2170   size_t n_completed_buffers = 0;
2171   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2172     n_completed_buffers++;
2173   }
2174   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2175   dcqs.clear_n_completed_buffers();
2176   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2177 }
2178 
2179 
2180 // Computes the sum of the storage used by the various regions.
2181 size_t G1CollectedHeap::used() const {
2182   return _allocator->used();
2183 }
2184 
2185 size_t G1CollectedHeap::used_unlocked() const {
2186   return _allocator->used_unlocked();
2187 }
2188 
2189 class SumUsedClosure: public HeapRegionClosure {
2190   size_t _used;
2191 public:
2192   SumUsedClosure() : _used(0) {}
2193   bool doHeapRegion(HeapRegion* r) {
2194     if (!r->is_continues_humongous()) {
2195       _used += r->used();
2196     }
2197     return false;
2198   }
2199   size_t result() { return _used; }
2200 };
2201 
2202 size_t G1CollectedHeap::recalculate_used() const {
2203   double recalculate_used_start = os::elapsedTime();
2204 
2205   SumUsedClosure blk;
2206   heap_region_iterate(&blk);
2207 
2208   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2209   return blk.result();
2210 }
2211 
2212 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2213   switch (cause) {
2214     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2215     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2216     case GCCause::_g1_humongous_allocation: return true;
2217     case GCCause::_update_allocation_context_stats_inc: return true;
2218     case GCCause::_wb_conc_mark:            return true;
2219     default:                                return false;
2220   }
2221 }
2222 
2223 #ifndef PRODUCT
2224 void G1CollectedHeap::allocate_dummy_regions() {
2225   // Let's fill up most of the region
2226   size_t word_size = HeapRegion::GrainWords - 1024;
2227   // And as a result the region we'll allocate will be humongous.
2228   guarantee(is_humongous(word_size), "sanity");
2229 
2230   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2231     // Let's use the existing mechanism for the allocation
2232     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2233                                                  AllocationContext::system());
2234     if (dummy_obj != NULL) {
2235       MemRegion mr(dummy_obj, word_size);
2236       CollectedHeap::fill_with_object(mr);
2237     } else {
2238       // If we can't allocate once, we probably cannot allocate
2239       // again. Let's get out of the loop.
2240       break;
2241     }
2242   }
2243 }
2244 #endif // !PRODUCT
2245 
2246 void G1CollectedHeap::increment_old_marking_cycles_started() {
2247   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2248     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2249     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2250     _old_marking_cycles_started, _old_marking_cycles_completed));
2251 
2252   _old_marking_cycles_started++;
2253 }
2254 
2255 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2256   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2257 
2258   // We assume that if concurrent == true, then the caller is a
2259   // concurrent thread that was joined the Suspendible Thread
2260   // Set. If there's ever a cheap way to check this, we should add an
2261   // assert here.
2262 
2263   // Given that this method is called at the end of a Full GC or of a
2264   // concurrent cycle, and those can be nested (i.e., a Full GC can
2265   // interrupt a concurrent cycle), the number of full collections
2266   // completed should be either one (in the case where there was no
2267   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2268   // behind the number of full collections started.
2269 
2270   // This is the case for the inner caller, i.e. a Full GC.
2271   assert(concurrent ||
2272          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2273          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2274          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2275                  "is inconsistent with _old_marking_cycles_completed = %u",
2276                  _old_marking_cycles_started, _old_marking_cycles_completed));
2277 
2278   // This is the case for the outer caller, i.e. the concurrent cycle.
2279   assert(!concurrent ||
2280          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2281          err_msg("for outer caller (concurrent cycle): "
2282                  "_old_marking_cycles_started = %u "
2283                  "is inconsistent with _old_marking_cycles_completed = %u",
2284                  _old_marking_cycles_started, _old_marking_cycles_completed));
2285 
2286   _old_marking_cycles_completed += 1;
2287 
2288   // We need to clear the "in_progress" flag in the CM thread before
2289   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2290   // is set) so that if a waiter requests another System.gc() it doesn't
2291   // incorrectly see that a marking cycle is still in progress.
2292   if (concurrent) {
2293     _cmThread->clear_in_progress();
2294   }
2295 
2296   // This notify_all() will ensure that a thread that called
2297   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2298   // and it's waiting for a full GC to finish will be woken up. It is
2299   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2300   FullGCCount_lock->notify_all();
2301 }
2302 
2303 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2304   _concurrent_cycle_started = true;
2305   _gc_timer_cm->register_gc_start(start_time);
2306 
2307   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2308   trace_heap_before_gc(_gc_tracer_cm);
2309 }
2310 
2311 void G1CollectedHeap::register_concurrent_cycle_end() {
2312   if (_concurrent_cycle_started) {
2313     if (_cm->has_aborted()) {
2314       _gc_tracer_cm->report_concurrent_mode_failure();
2315     }
2316 
2317     _gc_timer_cm->register_gc_end();
2318     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2319 
2320     // Clear state variables to prepare for the next concurrent cycle.
2321     _concurrent_cycle_started = false;
2322     _heap_summary_sent = false;
2323   }
2324 }
2325 
2326 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2327   if (_concurrent_cycle_started) {
2328     // This function can be called when:
2329     //  the cleanup pause is run
2330     //  the concurrent cycle is aborted before the cleanup pause.
2331     //  the concurrent cycle is aborted after the cleanup pause,
2332     //   but before the concurrent cycle end has been registered.
2333     // Make sure that we only send the heap information once.
2334     if (!_heap_summary_sent) {
2335       trace_heap_after_gc(_gc_tracer_cm);
2336       _heap_summary_sent = true;
2337     }
2338   }
2339 }
2340 
2341 G1YCType G1CollectedHeap::yc_type() {
2342   bool is_young = g1_policy()->gcs_are_young();
2343   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2344   bool is_during_mark = mark_in_progress();
2345 
2346   if (is_initial_mark) {
2347     return InitialMark;
2348   } else if (is_during_mark) {
2349     return DuringMark;
2350   } else if (is_young) {
2351     return Normal;
2352   } else {
2353     return Mixed;
2354   }
2355 }
2356 
2357 void G1CollectedHeap::collect(GCCause::Cause cause) {
2358   assert_heap_not_locked();
2359 
2360   uint gc_count_before;
2361   uint old_marking_count_before;
2362   uint full_gc_count_before;
2363   bool retry_gc;
2364 
2365   do {
2366     retry_gc = false;
2367 
2368     {
2369       MutexLocker ml(Heap_lock);
2370 
2371       // Read the GC count while holding the Heap_lock
2372       gc_count_before = total_collections();
2373       full_gc_count_before = total_full_collections();
2374       old_marking_count_before = _old_marking_cycles_started;
2375     }
2376 
2377     if (should_do_concurrent_full_gc(cause)) {
2378       // Schedule an initial-mark evacuation pause that will start a
2379       // concurrent cycle. We're setting word_size to 0 which means that
2380       // we are not requesting a post-GC allocation.
2381       VM_G1IncCollectionPause op(gc_count_before,
2382                                  0,     /* word_size */
2383                                  true,  /* should_initiate_conc_mark */
2384                                  g1_policy()->max_pause_time_ms(),
2385                                  cause);
2386       op.set_allocation_context(AllocationContext::current());
2387 
2388       VMThread::execute(&op);
2389       if (!op.pause_succeeded()) {
2390         if (old_marking_count_before == _old_marking_cycles_started) {
2391           retry_gc = op.should_retry_gc();
2392         } else {
2393           // A Full GC happened while we were trying to schedule the
2394           // initial-mark GC. No point in starting a new cycle given
2395           // that the whole heap was collected anyway.
2396         }
2397 
2398         if (retry_gc) {
2399           if (GC_locker::is_active_and_needs_gc()) {
2400             GC_locker::stall_until_clear();
2401           }
2402         }
2403       }
2404     } else {
2405       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2406           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2407 
2408         // Schedule a standard evacuation pause. We're setting word_size
2409         // to 0 which means that we are not requesting a post-GC allocation.
2410         VM_G1IncCollectionPause op(gc_count_before,
2411                                    0,     /* word_size */
2412                                    false, /* should_initiate_conc_mark */
2413                                    g1_policy()->max_pause_time_ms(),
2414                                    cause);
2415         VMThread::execute(&op);
2416       } else {
2417         // Schedule a Full GC.
2418         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2419         VMThread::execute(&op);
2420       }
2421     }
2422   } while (retry_gc);
2423 }
2424 
2425 bool G1CollectedHeap::is_in(const void* p) const {
2426   if (_hrm.reserved().contains(p)) {
2427     // Given that we know that p is in the reserved space,
2428     // heap_region_containing_raw() should successfully
2429     // return the containing region.
2430     HeapRegion* hr = heap_region_containing_raw(p);
2431     return hr->is_in(p);
2432   } else {
2433     return false;
2434   }
2435 }
2436 
2437 #ifdef ASSERT
2438 bool G1CollectedHeap::is_in_exact(const void* p) const {
2439   bool contains = reserved_region().contains(p);
2440   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2441   if (contains && available) {
2442     return true;
2443   } else {
2444     return false;
2445   }
2446 }
2447 #endif
2448 
2449 // Iteration functions.
2450 
2451 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2452 
2453 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2454   ExtendedOopClosure* _cl;
2455 public:
2456   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2457   bool doHeapRegion(HeapRegion* r) {
2458     if (!r->is_continues_humongous()) {
2459       r->oop_iterate(_cl);
2460     }
2461     return false;
2462   }
2463 };
2464 
2465 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2466   IterateOopClosureRegionClosure blk(cl);
2467   heap_region_iterate(&blk);
2468 }
2469 
2470 // Iterates an ObjectClosure over all objects within a HeapRegion.
2471 
2472 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2473   ObjectClosure* _cl;
2474 public:
2475   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2476   bool doHeapRegion(HeapRegion* r) {
2477     if (!r->is_continues_humongous()) {
2478       r->object_iterate(_cl);
2479     }
2480     return false;
2481   }
2482 };
2483 
2484 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2485   IterateObjectClosureRegionClosure blk(cl);
2486   heap_region_iterate(&blk);
2487 }
2488 
2489 // Calls a SpaceClosure on a HeapRegion.
2490 
2491 class SpaceClosureRegionClosure: public HeapRegionClosure {
2492   SpaceClosure* _cl;
2493 public:
2494   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2495   bool doHeapRegion(HeapRegion* r) {
2496     _cl->do_space(r);
2497     return false;
2498   }
2499 };
2500 
2501 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2502   SpaceClosureRegionClosure blk(cl);
2503   heap_region_iterate(&blk);
2504 }
2505 
2506 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2507   _hrm.iterate(cl);
2508 }
2509 
2510 void
2511 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2512                                          uint worker_id,
2513                                          HeapRegionClaimer *hrclaimer,
2514                                          bool concurrent) const {
2515   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2516 }
2517 
2518 // Clear the cached CSet starting regions and (more importantly)
2519 // the time stamps. Called when we reset the GC time stamp.
2520 void G1CollectedHeap::clear_cset_start_regions() {
2521   assert(_worker_cset_start_region != NULL, "sanity");
2522   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2523 
2524   int n_queues = MAX2((int)ParallelGCThreads, 1);
2525   for (int i = 0; i < n_queues; i++) {
2526     _worker_cset_start_region[i] = NULL;
2527     _worker_cset_start_region_time_stamp[i] = 0;
2528   }
2529 }
2530 
2531 // Given the id of a worker, obtain or calculate a suitable
2532 // starting region for iterating over the current collection set.
2533 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2534   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2535 
2536   HeapRegion* result = NULL;
2537   unsigned gc_time_stamp = get_gc_time_stamp();
2538 
2539   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2540     // Cached starting region for current worker was set
2541     // during the current pause - so it's valid.
2542     // Note: the cached starting heap region may be NULL
2543     // (when the collection set is empty).
2544     result = _worker_cset_start_region[worker_i];
2545     assert(result == NULL || result->in_collection_set(), "sanity");
2546     return result;
2547   }
2548 
2549   // The cached entry was not valid so let's calculate
2550   // a suitable starting heap region for this worker.
2551 
2552   // We want the parallel threads to start their collection
2553   // set iteration at different collection set regions to
2554   // avoid contention.
2555   // If we have:
2556   //          n collection set regions
2557   //          p threads
2558   // Then thread t will start at region floor ((t * n) / p)
2559 
2560   result = g1_policy()->collection_set();
2561   uint cs_size = g1_policy()->cset_region_length();
2562   uint active_workers = workers()->active_workers();
2563   assert(UseDynamicNumberOfGCThreads ||
2564            active_workers == workers()->total_workers(),
2565            "Unless dynamic should use total workers");
2566 
2567   uint end_ind   = (cs_size * worker_i) / active_workers;
2568   uint start_ind = 0;
2569 
2570   if (worker_i > 0 &&
2571       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2572     // Previous workers starting region is valid
2573     // so let's iterate from there
2574     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2575     result = _worker_cset_start_region[worker_i - 1];
2576   }
2577 
2578   for (uint i = start_ind; i < end_ind; i++) {
2579     result = result->next_in_collection_set();
2580   }
2581 
2582   // Note: the calculated starting heap region may be NULL
2583   // (when the collection set is empty).
2584   assert(result == NULL || result->in_collection_set(), "sanity");
2585   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2586          "should be updated only once per pause");
2587   _worker_cset_start_region[worker_i] = result;
2588   OrderAccess::storestore();
2589   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2590   return result;
2591 }
2592 
2593 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2594   HeapRegion* r = g1_policy()->collection_set();
2595   while (r != NULL) {
2596     HeapRegion* next = r->next_in_collection_set();
2597     if (cl->doHeapRegion(r)) {
2598       cl->incomplete();
2599       return;
2600     }
2601     r = next;
2602   }
2603 }
2604 
2605 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2606                                                   HeapRegionClosure *cl) {
2607   if (r == NULL) {
2608     // The CSet is empty so there's nothing to do.
2609     return;
2610   }
2611 
2612   assert(r->in_collection_set(),
2613          "Start region must be a member of the collection set.");
2614   HeapRegion* cur = r;
2615   while (cur != NULL) {
2616     HeapRegion* next = cur->next_in_collection_set();
2617     if (cl->doHeapRegion(cur) && false) {
2618       cl->incomplete();
2619       return;
2620     }
2621     cur = next;
2622   }
2623   cur = g1_policy()->collection_set();
2624   while (cur != r) {
2625     HeapRegion* next = cur->next_in_collection_set();
2626     if (cl->doHeapRegion(cur) && false) {
2627       cl->incomplete();
2628       return;
2629     }
2630     cur = next;
2631   }
2632 }
2633 
2634 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2635   HeapRegion* result = _hrm.next_region_in_heap(from);
2636   while (result != NULL && result->is_humongous()) {
2637     result = _hrm.next_region_in_heap(result);
2638   }
2639   return result;
2640 }
2641 
2642 Space* G1CollectedHeap::space_containing(const void* addr) const {
2643   return heap_region_containing(addr);
2644 }
2645 
2646 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2647   Space* sp = space_containing(addr);
2648   return sp->block_start(addr);
2649 }
2650 
2651 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2652   Space* sp = space_containing(addr);
2653   return sp->block_size(addr);
2654 }
2655 
2656 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2657   Space* sp = space_containing(addr);
2658   return sp->block_is_obj(addr);
2659 }
2660 
2661 bool G1CollectedHeap::supports_tlab_allocation() const {
2662   return true;
2663 }
2664 
2665 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2666   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2667 }
2668 
2669 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2670   return young_list()->eden_used_bytes();
2671 }
2672 
2673 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2674 // must be smaller than the humongous object limit.
2675 size_t G1CollectedHeap::max_tlab_size() const {
2676   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2677 }
2678 
2679 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2680   // Return the remaining space in the cur alloc region, but not less than
2681   // the min TLAB size.
2682 
2683   // Also, this value can be at most the humongous object threshold,
2684   // since we can't allow tlabs to grow big enough to accommodate
2685   // humongous objects.
2686 
2687   HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2688   size_t max_tlab = max_tlab_size() * wordSize;
2689   if (hr == NULL) {
2690     return max_tlab;
2691   } else {
2692     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2693   }
2694 }
2695 
2696 size_t G1CollectedHeap::max_capacity() const {
2697   return _hrm.reserved().byte_size();
2698 }
2699 
2700 jlong G1CollectedHeap::millis_since_last_gc() {
2701   // assert(false, "NYI");
2702   return 0;
2703 }
2704 
2705 void G1CollectedHeap::prepare_for_verify() {
2706   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2707     ensure_parsability(false);
2708   }
2709   g1_rem_set()->prepare_for_verify();
2710 }
2711 
2712 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2713                                               VerifyOption vo) {
2714   switch (vo) {
2715   case VerifyOption_G1UsePrevMarking:
2716     return hr->obj_allocated_since_prev_marking(obj);
2717   case VerifyOption_G1UseNextMarking:
2718     return hr->obj_allocated_since_next_marking(obj);
2719   case VerifyOption_G1UseMarkWord:
2720     return false;
2721   default:
2722     ShouldNotReachHere();
2723   }
2724   return false; // keep some compilers happy
2725 }
2726 
2727 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2728   switch (vo) {
2729   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2730   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2731   case VerifyOption_G1UseMarkWord:    return NULL;
2732   default:                            ShouldNotReachHere();
2733   }
2734   return NULL; // keep some compilers happy
2735 }
2736 
2737 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2738   switch (vo) {
2739   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2740   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2741   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2742   default:                            ShouldNotReachHere();
2743   }
2744   return false; // keep some compilers happy
2745 }
2746 
2747 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2748   switch (vo) {
2749   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2750   case VerifyOption_G1UseNextMarking: return "NTAMS";
2751   case VerifyOption_G1UseMarkWord:    return "NONE";
2752   default:                            ShouldNotReachHere();
2753   }
2754   return NULL; // keep some compilers happy
2755 }
2756 
2757 class VerifyRootsClosure: public OopClosure {
2758 private:
2759   G1CollectedHeap* _g1h;
2760   VerifyOption     _vo;
2761   bool             _failures;
2762 public:
2763   // _vo == UsePrevMarking -> use "prev" marking information,
2764   // _vo == UseNextMarking -> use "next" marking information,
2765   // _vo == UseMarkWord    -> use mark word from object header.
2766   VerifyRootsClosure(VerifyOption vo) :
2767     _g1h(G1CollectedHeap::heap()),
2768     _vo(vo),
2769     _failures(false) { }
2770 
2771   bool failures() { return _failures; }
2772 
2773   template <class T> void do_oop_nv(T* p) {
2774     T heap_oop = oopDesc::load_heap_oop(p);
2775     if (!oopDesc::is_null(heap_oop)) {
2776       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2777       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2778         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2779                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2780         if (_vo == VerifyOption_G1UseMarkWord) {
2781           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2782         }
2783         obj->print_on(gclog_or_tty);
2784         _failures = true;
2785       }
2786     }
2787   }
2788 
2789   void do_oop(oop* p)       { do_oop_nv(p); }
2790   void do_oop(narrowOop* p) { do_oop_nv(p); }
2791 };
2792 
2793 class G1VerifyCodeRootOopClosure: public OopClosure {
2794   G1CollectedHeap* _g1h;
2795   OopClosure* _root_cl;
2796   nmethod* _nm;
2797   VerifyOption _vo;
2798   bool _failures;
2799 
2800   template <class T> void do_oop_work(T* p) {
2801     // First verify that this root is live
2802     _root_cl->do_oop(p);
2803 
2804     if (!G1VerifyHeapRegionCodeRoots) {
2805       // We're not verifying the code roots attached to heap region.
2806       return;
2807     }
2808 
2809     // Don't check the code roots during marking verification in a full GC
2810     if (_vo == VerifyOption_G1UseMarkWord) {
2811       return;
2812     }
2813 
2814     // Now verify that the current nmethod (which contains p) is
2815     // in the code root list of the heap region containing the
2816     // object referenced by p.
2817 
2818     T heap_oop = oopDesc::load_heap_oop(p);
2819     if (!oopDesc::is_null(heap_oop)) {
2820       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2821 
2822       // Now fetch the region containing the object
2823       HeapRegion* hr = _g1h->heap_region_containing(obj);
2824       HeapRegionRemSet* hrrs = hr->rem_set();
2825       // Verify that the strong code root list for this region
2826       // contains the nmethod
2827       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2828         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2829                               "from nmethod "PTR_FORMAT" not in strong "
2830                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2831                               p, _nm, hr->bottom(), hr->end());
2832         _failures = true;
2833       }
2834     }
2835   }
2836 
2837 public:
2838   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2839     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2840 
2841   void do_oop(oop* p) { do_oop_work(p); }
2842   void do_oop(narrowOop* p) { do_oop_work(p); }
2843 
2844   void set_nmethod(nmethod* nm) { _nm = nm; }
2845   bool failures() { return _failures; }
2846 };
2847 
2848 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2849   G1VerifyCodeRootOopClosure* _oop_cl;
2850 
2851 public:
2852   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2853     _oop_cl(oop_cl) {}
2854 
2855   void do_code_blob(CodeBlob* cb) {
2856     nmethod* nm = cb->as_nmethod_or_null();
2857     if (nm != NULL) {
2858       _oop_cl->set_nmethod(nm);
2859       nm->oops_do(_oop_cl);
2860     }
2861   }
2862 };
2863 
2864 class YoungRefCounterClosure : public OopClosure {
2865   G1CollectedHeap* _g1h;
2866   int              _count;
2867  public:
2868   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2869   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2870   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2871 
2872   int count() { return _count; }
2873   void reset_count() { _count = 0; };
2874 };
2875 
2876 class VerifyKlassClosure: public KlassClosure {
2877   YoungRefCounterClosure _young_ref_counter_closure;
2878   OopClosure *_oop_closure;
2879  public:
2880   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2881   void do_klass(Klass* k) {
2882     k->oops_do(_oop_closure);
2883 
2884     _young_ref_counter_closure.reset_count();
2885     k->oops_do(&_young_ref_counter_closure);
2886     if (_young_ref_counter_closure.count() > 0) {
2887       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2888     }
2889   }
2890 };
2891 
2892 class VerifyLivenessOopClosure: public OopClosure {
2893   G1CollectedHeap* _g1h;
2894   VerifyOption _vo;
2895 public:
2896   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2897     _g1h(g1h), _vo(vo)
2898   { }
2899   void do_oop(narrowOop *p) { do_oop_work(p); }
2900   void do_oop(      oop *p) { do_oop_work(p); }
2901 
2902   template <class T> void do_oop_work(T *p) {
2903     oop obj = oopDesc::load_decode_heap_oop(p);
2904     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2905               "Dead object referenced by a not dead object");
2906   }
2907 };
2908 
2909 class VerifyObjsInRegionClosure: public ObjectClosure {
2910 private:
2911   G1CollectedHeap* _g1h;
2912   size_t _live_bytes;
2913   HeapRegion *_hr;
2914   VerifyOption _vo;
2915 public:
2916   // _vo == UsePrevMarking -> use "prev" marking information,
2917   // _vo == UseNextMarking -> use "next" marking information,
2918   // _vo == UseMarkWord    -> use mark word from object header.
2919   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2920     : _live_bytes(0), _hr(hr), _vo(vo) {
2921     _g1h = G1CollectedHeap::heap();
2922   }
2923   void do_object(oop o) {
2924     VerifyLivenessOopClosure isLive(_g1h, _vo);
2925     assert(o != NULL, "Huh?");
2926     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2927       // If the object is alive according to the mark word,
2928       // then verify that the marking information agrees.
2929       // Note we can't verify the contra-positive of the
2930       // above: if the object is dead (according to the mark
2931       // word), it may not be marked, or may have been marked
2932       // but has since became dead, or may have been allocated
2933       // since the last marking.
2934       if (_vo == VerifyOption_G1UseMarkWord) {
2935         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2936       }
2937 
2938       o->oop_iterate_no_header(&isLive);
2939       if (!_hr->obj_allocated_since_prev_marking(o)) {
2940         size_t obj_size = o->size();    // Make sure we don't overflow
2941         _live_bytes += (obj_size * HeapWordSize);
2942       }
2943     }
2944   }
2945   size_t live_bytes() { return _live_bytes; }
2946 };
2947 
2948 class PrintObjsInRegionClosure : public ObjectClosure {
2949   HeapRegion *_hr;
2950   G1CollectedHeap *_g1;
2951 public:
2952   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2953     _g1 = G1CollectedHeap::heap();
2954   };
2955 
2956   void do_object(oop o) {
2957     if (o != NULL) {
2958       HeapWord *start = (HeapWord *) o;
2959       size_t word_sz = o->size();
2960       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2961                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2962                           (void*) o, word_sz,
2963                           _g1->isMarkedPrev(o),
2964                           _g1->isMarkedNext(o),
2965                           _hr->obj_allocated_since_prev_marking(o));
2966       HeapWord *end = start + word_sz;
2967       HeapWord *cur;
2968       int *val;
2969       for (cur = start; cur < end; cur++) {
2970         val = (int *) cur;
2971         gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2972       }
2973     }
2974   }
2975 };
2976 
2977 class VerifyRegionClosure: public HeapRegionClosure {
2978 private:
2979   bool             _par;
2980   VerifyOption     _vo;
2981   bool             _failures;
2982 public:
2983   // _vo == UsePrevMarking -> use "prev" marking information,
2984   // _vo == UseNextMarking -> use "next" marking information,
2985   // _vo == UseMarkWord    -> use mark word from object header.
2986   VerifyRegionClosure(bool par, VerifyOption vo)
2987     : _par(par),
2988       _vo(vo),
2989       _failures(false) {}
2990 
2991   bool failures() {
2992     return _failures;
2993   }
2994 
2995   bool doHeapRegion(HeapRegion* r) {
2996     if (!r->is_continues_humongous()) {
2997       bool failures = false;
2998       r->verify(_vo, &failures);
2999       if (failures) {
3000         _failures = true;
3001       } else {
3002         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3003         r->object_iterate(&not_dead_yet_cl);
3004         if (_vo != VerifyOption_G1UseNextMarking) {
3005           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3006             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3007                                    "max_live_bytes "SIZE_FORMAT" "
3008                                    "< calculated "SIZE_FORMAT,
3009                                    r->bottom(), r->end(),
3010                                    r->max_live_bytes(),
3011                                  not_dead_yet_cl.live_bytes());
3012             _failures = true;
3013           }
3014         } else {
3015           // When vo == UseNextMarking we cannot currently do a sanity
3016           // check on the live bytes as the calculation has not been
3017           // finalized yet.
3018         }
3019       }
3020     }
3021     return false; // stop the region iteration if we hit a failure
3022   }
3023 };
3024 
3025 // This is the task used for parallel verification of the heap regions
3026 
3027 class G1ParVerifyTask: public AbstractGangTask {
3028 private:
3029   G1CollectedHeap*  _g1h;
3030   VerifyOption      _vo;
3031   bool              _failures;
3032   HeapRegionClaimer _hrclaimer;
3033 
3034 public:
3035   // _vo == UsePrevMarking -> use "prev" marking information,
3036   // _vo == UseNextMarking -> use "next" marking information,
3037   // _vo == UseMarkWord    -> use mark word from object header.
3038   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3039       AbstractGangTask("Parallel verify task"),
3040       _g1h(g1h),
3041       _vo(vo),
3042       _failures(false),
3043       _hrclaimer(g1h->workers()->active_workers()) {}
3044 
3045   bool failures() {
3046     return _failures;
3047   }
3048 
3049   void work(uint worker_id) {
3050     HandleMark hm;
3051     VerifyRegionClosure blk(true, _vo);
3052     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3053     if (blk.failures()) {
3054       _failures = true;
3055     }
3056   }
3057 };
3058 
3059 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3060   if (SafepointSynchronize::is_at_safepoint()) {
3061     assert(Thread::current()->is_VM_thread(),
3062            "Expected to be executed serially by the VM thread at this point");
3063 
3064     if (!silent) { gclog_or_tty->print("Roots "); }
3065     VerifyRootsClosure rootsCl(vo);
3066     VerifyKlassClosure klassCl(this, &rootsCl);
3067     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3068 
3069     // We apply the relevant closures to all the oops in the
3070     // system dictionary, class loader data graph, the string table
3071     // and the nmethods in the code cache.
3072     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3073     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3074 
3075     {
3076       G1RootProcessor root_processor(this);
3077       root_processor.process_all_roots(&rootsCl,
3078                                        &cldCl,
3079                                        &blobsCl);
3080     }
3081 
3082     bool failures = rootsCl.failures() || codeRootsCl.failures();
3083 
3084     if (vo != VerifyOption_G1UseMarkWord) {
3085       // If we're verifying during a full GC then the region sets
3086       // will have been torn down at the start of the GC. Therefore
3087       // verifying the region sets will fail. So we only verify
3088       // the region sets when not in a full GC.
3089       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3090       verify_region_sets();
3091     }
3092 
3093     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3094     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3095 
3096       G1ParVerifyTask task(this, vo);
3097       assert(UseDynamicNumberOfGCThreads ||
3098         workers()->active_workers() == workers()->total_workers(),
3099         "If not dynamic should be using all the workers");
3100       int n_workers = workers()->active_workers();
3101       set_par_threads(n_workers);
3102       workers()->run_task(&task);
3103       set_par_threads(0);
3104       if (task.failures()) {
3105         failures = true;
3106       }
3107 
3108     } else {
3109       VerifyRegionClosure blk(false, vo);
3110       heap_region_iterate(&blk);
3111       if (blk.failures()) {
3112         failures = true;
3113       }
3114     }
3115 
3116     if (G1StringDedup::is_enabled()) {
3117       if (!silent) gclog_or_tty->print("StrDedup ");
3118       G1StringDedup::verify();
3119     }
3120 
3121     if (failures) {
3122       gclog_or_tty->print_cr("Heap:");
3123       // It helps to have the per-region information in the output to
3124       // help us track down what went wrong. This is why we call
3125       // print_extended_on() instead of print_on().
3126       print_extended_on(gclog_or_tty);
3127       gclog_or_tty->cr();
3128 #ifndef PRODUCT
3129       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3130         concurrent_mark()->print_reachable("at-verification-failure",
3131                                            vo, false /* all */);
3132       }
3133 #endif
3134       gclog_or_tty->flush();
3135     }
3136     guarantee(!failures, "there should not have been any failures");
3137   } else {
3138     if (!silent) {
3139       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3140       if (G1StringDedup::is_enabled()) {
3141         gclog_or_tty->print(", StrDedup");
3142       }
3143       gclog_or_tty->print(") ");
3144     }
3145   }
3146 }
3147 
3148 void G1CollectedHeap::verify(bool silent) {
3149   verify(silent, VerifyOption_G1UsePrevMarking);
3150 }
3151 
3152 double G1CollectedHeap::verify(bool guard, const char* msg) {
3153   double verify_time_ms = 0.0;
3154 
3155   if (guard && total_collections() >= VerifyGCStartAt) {
3156     double verify_start = os::elapsedTime();
3157     HandleMark hm;  // Discard invalid handles created during verification
3158     prepare_for_verify();
3159     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3160     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3161   }
3162 
3163   return verify_time_ms;
3164 }
3165 
3166 void G1CollectedHeap::verify_before_gc() {
3167   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3168   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3169 }
3170 
3171 void G1CollectedHeap::verify_after_gc() {
3172   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3173   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3174 }
3175 
3176 class PrintRegionClosure: public HeapRegionClosure {
3177   outputStream* _st;
3178 public:
3179   PrintRegionClosure(outputStream* st) : _st(st) {}
3180   bool doHeapRegion(HeapRegion* r) {
3181     r->print_on(_st);
3182     return false;
3183   }
3184 };
3185 
3186 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3187                                        const HeapRegion* hr,
3188                                        const VerifyOption vo) const {
3189   switch (vo) {
3190   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3191   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3192   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3193   default:                            ShouldNotReachHere();
3194   }
3195   return false; // keep some compilers happy
3196 }
3197 
3198 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3199                                        const VerifyOption vo) const {
3200   switch (vo) {
3201   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3202   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3203   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3204   default:                            ShouldNotReachHere();
3205   }
3206   return false; // keep some compilers happy
3207 }
3208 
3209 void G1CollectedHeap::print_on(outputStream* st) const {
3210   st->print(" %-20s", "garbage-first heap");
3211   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3212             capacity()/K, used_unlocked()/K);
3213   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3214             _hrm.reserved().start(),
3215             _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3216             _hrm.reserved().end());
3217   st->cr();
3218   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3219   uint young_regions = _young_list->length();
3220   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3221             (size_t) young_regions * HeapRegion::GrainBytes / K);
3222   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3223   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3224             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3225   st->cr();
3226   MetaspaceAux::print_on(st);
3227 }
3228 
3229 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3230   print_on(st);
3231 
3232   // Print the per-region information.
3233   st->cr();
3234   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3235                "HS=humongous(starts), HC=humongous(continues), "
3236                "CS=collection set, F=free, TS=gc time stamp, "
3237                "PTAMS=previous top-at-mark-start, "
3238                "NTAMS=next top-at-mark-start)");
3239   PrintRegionClosure blk(st);
3240   heap_region_iterate(&blk);
3241 }
3242 
3243 void G1CollectedHeap::print_on_error(outputStream* st) const {
3244   this->CollectedHeap::print_on_error(st);
3245 
3246   if (_cm != NULL) {
3247     st->cr();
3248     _cm->print_on_error(st);
3249   }
3250 }
3251 
3252 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3253   workers()->print_worker_threads_on(st);
3254   _cmThread->print_on(st);
3255   st->cr();
3256   _cm->print_worker_threads_on(st);
3257   _cg1r->print_worker_threads_on(st);
3258   if (G1StringDedup::is_enabled()) {
3259     G1StringDedup::print_worker_threads_on(st);
3260   }
3261 }
3262 
3263 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3264   workers()->threads_do(tc);
3265   tc->do_thread(_cmThread);
3266   _cg1r->threads_do(tc);
3267   if (G1StringDedup::is_enabled()) {
3268     G1StringDedup::threads_do(tc);
3269   }
3270 }
3271 
3272 void G1CollectedHeap::print_tracing_info() const {
3273   // We'll overload this to mean "trace GC pause statistics."
3274   if (TraceYoungGenTime || TraceOldGenTime) {
3275     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3276     // to that.
3277     g1_policy()->print_tracing_info();
3278   }
3279   if (G1SummarizeRSetStats) {
3280     g1_rem_set()->print_summary_info();
3281   }
3282   if (G1SummarizeConcMark) {
3283     concurrent_mark()->print_summary_info();
3284   }
3285   g1_policy()->print_yg_surv_rate_info();
3286 }
3287 
3288 #ifndef PRODUCT
3289 // Helpful for debugging RSet issues.
3290 
3291 class PrintRSetsClosure : public HeapRegionClosure {
3292 private:
3293   const char* _msg;
3294   size_t _occupied_sum;
3295 
3296 public:
3297   bool doHeapRegion(HeapRegion* r) {
3298     HeapRegionRemSet* hrrs = r->rem_set();
3299     size_t occupied = hrrs->occupied();
3300     _occupied_sum += occupied;
3301 
3302     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3303                            HR_FORMAT_PARAMS(r));
3304     if (occupied == 0) {
3305       gclog_or_tty->print_cr("  RSet is empty");
3306     } else {
3307       hrrs->print();
3308     }
3309     gclog_or_tty->print_cr("----------");
3310     return false;
3311   }
3312 
3313   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3314     gclog_or_tty->cr();
3315     gclog_or_tty->print_cr("========================================");
3316     gclog_or_tty->print_cr("%s", msg);
3317     gclog_or_tty->cr();
3318   }
3319 
3320   ~PrintRSetsClosure() {
3321     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3322     gclog_or_tty->print_cr("========================================");
3323     gclog_or_tty->cr();
3324   }
3325 };
3326 
3327 void G1CollectedHeap::print_cset_rsets() {
3328   PrintRSetsClosure cl("Printing CSet RSets");
3329   collection_set_iterate(&cl);
3330 }
3331 
3332 void G1CollectedHeap::print_all_rsets() {
3333   PrintRSetsClosure cl("Printing All RSets");;
3334   heap_region_iterate(&cl);
3335 }
3336 #endif // PRODUCT
3337 
3338 G1CollectedHeap* G1CollectedHeap::heap() {
3339   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3340          "not a garbage-first heap");
3341   return _g1h;
3342 }
3343 
3344 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3345   // always_do_update_barrier = false;
3346   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3347   // Fill TLAB's and such
3348   accumulate_statistics_all_tlabs();
3349   ensure_parsability(true);
3350 
3351   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3352       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3353     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3354   }
3355 }
3356 
3357 void G1CollectedHeap::gc_epilogue(bool full) {
3358 
3359   if (G1SummarizeRSetStats &&
3360       (G1SummarizeRSetStatsPeriod > 0) &&
3361       // we are at the end of the GC. Total collections has already been increased.
3362       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3363     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3364   }
3365 
3366   // FIXME: what is this about?
3367   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3368   // is set.
3369   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3370                         "derived pointer present"));
3371   // always_do_update_barrier = true;
3372 
3373   resize_all_tlabs();
3374   allocation_context_stats().update(full);
3375 
3376   // We have just completed a GC. Update the soft reference
3377   // policy with the new heap occupancy
3378   Universe::update_heap_info_at_gc();
3379 }
3380 
3381 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3382                                                uint gc_count_before,
3383                                                bool* succeeded,
3384                                                GCCause::Cause gc_cause) {
3385   assert_heap_not_locked_and_not_at_safepoint();
3386   g1_policy()->record_stop_world_start();
3387   VM_G1IncCollectionPause op(gc_count_before,
3388                              word_size,
3389                              false, /* should_initiate_conc_mark */
3390                              g1_policy()->max_pause_time_ms(),
3391                              gc_cause);
3392 
3393   op.set_allocation_context(AllocationContext::current());
3394   VMThread::execute(&op);
3395 
3396   HeapWord* result = op.result();
3397   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3398   assert(result == NULL || ret_succeeded,
3399          "the result should be NULL if the VM did not succeed");
3400   *succeeded = ret_succeeded;
3401 
3402   assert_heap_not_locked();
3403   return result;
3404 }
3405 
3406 void
3407 G1CollectedHeap::doConcurrentMark() {
3408   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3409   if (!_cmThread->in_progress()) {
3410     _cmThread->set_started();
3411     CGC_lock->notify();
3412   }
3413 }
3414 
3415 size_t G1CollectedHeap::pending_card_num() {
3416   size_t extra_cards = 0;
3417   JavaThread *curr = Threads::first();
3418   while (curr != NULL) {
3419     DirtyCardQueue& dcq = curr->dirty_card_queue();
3420     extra_cards += dcq.size();
3421     curr = curr->next();
3422   }
3423   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3424   size_t buffer_size = dcqs.buffer_size();
3425   size_t buffer_num = dcqs.completed_buffers_num();
3426 
3427   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3428   // in bytes - not the number of 'entries'. We need to convert
3429   // into a number of cards.
3430   return (buffer_size * buffer_num + extra_cards) / oopSize;
3431 }
3432 
3433 size_t G1CollectedHeap::cards_scanned() {
3434   return g1_rem_set()->cardsScanned();
3435 }
3436 
3437 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3438   HeapRegion* region = region_at(index);
3439   assert(region->is_starts_humongous(), "Must start a humongous object");
3440   return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3441 }
3442 
3443 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3444  private:
3445   size_t _total_humongous;
3446   size_t _candidate_humongous;
3447 
3448   DirtyCardQueue _dcq;
3449 
3450   bool humongous_region_is_candidate(uint index) {
3451     HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3452     assert(region->is_starts_humongous(), "Must start a humongous object");
3453     HeapRegionRemSet* const rset = region->rem_set();
3454     bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3455     return !oop(region->bottom())->is_objArray() &&
3456            ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3457             (!allow_stale_refs && rset->is_empty()));
3458   }
3459 
3460  public:
3461   RegisterHumongousWithInCSetFastTestClosure()
3462   : _total_humongous(0),
3463     _candidate_humongous(0),
3464     _dcq(&JavaThread::dirty_card_queue_set()) {
3465   }
3466 
3467   virtual bool doHeapRegion(HeapRegion* r) {
3468     if (!r->is_starts_humongous()) {
3469       return false;
3470     }
3471     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3472 
3473     uint region_idx = r->hrm_index();
3474     bool is_candidate = humongous_region_is_candidate(region_idx);
3475     // Is_candidate already filters out humongous object with large remembered sets.
3476     // If we have a humongous object with a few remembered sets, we simply flush these
3477     // remembered set entries into the DCQS. That will result in automatic
3478     // re-evaluation of their remembered set entries during the following evacuation
3479     // phase.
3480     if (is_candidate) {
3481       if (!r->rem_set()->is_empty()) {
3482         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3483                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3484         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3485         HeapRegionRemSetIterator hrrs(r->rem_set());
3486         size_t card_index;
3487         while (hrrs.has_next(card_index)) {
3488           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3489           // The remembered set might contain references to already freed
3490           // regions. Filter out such entries to avoid failing card table
3491           // verification.
3492           if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3493             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3494               *card_ptr = CardTableModRefBS::dirty_card_val();
3495               _dcq.enqueue(card_ptr);
3496             }
3497           }
3498         }
3499         r->rem_set()->clear_locked();
3500       }
3501       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3502       g1h->register_humongous_region_with_cset(region_idx);
3503       _candidate_humongous++;
3504     }
3505     _total_humongous++;
3506 
3507     return false;
3508   }
3509 
3510   size_t total_humongous() const { return _total_humongous; }
3511   size_t candidate_humongous() const { return _candidate_humongous; }
3512 
3513   void flush_rem_set_entries() { _dcq.flush(); }
3514 };
3515 
3516 void G1CollectedHeap::register_humongous_regions_with_cset() {
3517   if (!G1EagerReclaimHumongousObjects) {
3518     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3519     return;
3520   }
3521   double time = os::elapsed_counter();
3522 
3523   RegisterHumongousWithInCSetFastTestClosure cl;
3524   heap_region_iterate(&cl);
3525 
3526   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3527   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3528                                                                   cl.total_humongous(),
3529                                                                   cl.candidate_humongous());
3530   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3531 
3532   if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3533     clear_humongous_is_live_table();
3534   }
3535 
3536   // Finally flush all remembered set entries to re-check into the global DCQS.
3537   cl.flush_rem_set_entries();
3538 }
3539 
3540 void
3541 G1CollectedHeap::setup_surviving_young_words() {
3542   assert(_surviving_young_words == NULL, "pre-condition");
3543   uint array_length = g1_policy()->young_cset_region_length();
3544   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3545   if (_surviving_young_words == NULL) {
3546     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3547                           "Not enough space for young surv words summary.");
3548   }
3549   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3550 #ifdef ASSERT
3551   for (uint i = 0;  i < array_length; ++i) {
3552     assert( _surviving_young_words[i] == 0, "memset above" );
3553   }
3554 #endif // !ASSERT
3555 }
3556 
3557 void
3558 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3559   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3560   uint array_length = g1_policy()->young_cset_region_length();
3561   for (uint i = 0; i < array_length; ++i) {
3562     _surviving_young_words[i] += surv_young_words[i];
3563   }
3564 }
3565 
3566 void
3567 G1CollectedHeap::cleanup_surviving_young_words() {
3568   guarantee( _surviving_young_words != NULL, "pre-condition" );
3569   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3570   _surviving_young_words = NULL;
3571 }
3572 
3573 #ifdef ASSERT
3574 class VerifyCSetClosure: public HeapRegionClosure {
3575 public:
3576   bool doHeapRegion(HeapRegion* hr) {
3577     // Here we check that the CSet region's RSet is ready for parallel
3578     // iteration. The fields that we'll verify are only manipulated
3579     // when the region is part of a CSet and is collected. Afterwards,
3580     // we reset these fields when we clear the region's RSet (when the
3581     // region is freed) so they are ready when the region is
3582     // re-allocated. The only exception to this is if there's an
3583     // evacuation failure and instead of freeing the region we leave
3584     // it in the heap. In that case, we reset these fields during
3585     // evacuation failure handling.
3586     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3587 
3588     // Here's a good place to add any other checks we'd like to
3589     // perform on CSet regions.
3590     return false;
3591   }
3592 };
3593 #endif // ASSERT
3594 
3595 #if TASKQUEUE_STATS
3596 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3597   st->print_raw_cr("GC Task Stats");
3598   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3599   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3600 }
3601 
3602 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3603   print_taskqueue_stats_hdr(st);
3604 
3605   TaskQueueStats totals;
3606   const int n = workers()->total_workers();
3607   for (int i = 0; i < n; ++i) {
3608     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3609     totals += task_queue(i)->stats;
3610   }
3611   st->print_raw("tot "); totals.print(st); st->cr();
3612 
3613   DEBUG_ONLY(totals.verify());
3614 }
3615 
3616 void G1CollectedHeap::reset_taskqueue_stats() {
3617   const int n = workers()->total_workers();
3618   for (int i = 0; i < n; ++i) {
3619     task_queue(i)->stats.reset();
3620   }
3621 }
3622 #endif // TASKQUEUE_STATS
3623 
3624 void G1CollectedHeap::log_gc_header() {
3625   if (!G1Log::fine()) {
3626     return;
3627   }
3628 
3629   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3630 
3631   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3632     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3633     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3634 
3635   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3636 }
3637 
3638 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3639   if (!G1Log::fine()) {
3640     return;
3641   }
3642 
3643   if (G1Log::finer()) {
3644     if (evacuation_failed()) {
3645       gclog_or_tty->print(" (to-space exhausted)");
3646     }
3647     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3648     g1_policy()->phase_times()->note_gc_end();
3649     g1_policy()->phase_times()->print(pause_time_sec);
3650     g1_policy()->print_detailed_heap_transition();
3651   } else {
3652     if (evacuation_failed()) {
3653       gclog_or_tty->print("--");
3654     }
3655     g1_policy()->print_heap_transition();
3656     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3657   }
3658   gclog_or_tty->flush();
3659 }
3660 
3661 bool
3662 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3663   assert_at_safepoint(true /* should_be_vm_thread */);
3664   guarantee(!is_gc_active(), "collection is not reentrant");
3665 
3666   if (GC_locker::check_active_before_gc()) {
3667     return false;
3668   }
3669 
3670   _gc_timer_stw->register_gc_start();
3671 
3672   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3673 
3674   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3675   ResourceMark rm;
3676 
3677   print_heap_before_gc();
3678   trace_heap_before_gc(_gc_tracer_stw);
3679 
3680   verify_region_sets_optional();
3681   verify_dirty_young_regions();
3682 
3683   // This call will decide whether this pause is an initial-mark
3684   // pause. If it is, during_initial_mark_pause() will return true
3685   // for the duration of this pause.
3686   g1_policy()->decide_on_conc_mark_initiation();
3687 
3688   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3689   assert(!g1_policy()->during_initial_mark_pause() ||
3690           g1_policy()->gcs_are_young(), "sanity");
3691 
3692   // We also do not allow mixed GCs during marking.
3693   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3694 
3695   // Record whether this pause is an initial mark. When the current
3696   // thread has completed its logging output and it's safe to signal
3697   // the CM thread, the flag's value in the policy has been reset.
3698   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3699 
3700   // Inner scope for scope based logging, timers, and stats collection
3701   {
3702     EvacuationInfo evacuation_info;
3703 
3704     if (g1_policy()->during_initial_mark_pause()) {
3705       // We are about to start a marking cycle, so we increment the
3706       // full collection counter.
3707       increment_old_marking_cycles_started();
3708       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3709     }
3710 
3711     _gc_tracer_stw->report_yc_type(yc_type());
3712 
3713     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3714 
3715     uint active_workers = workers()->active_workers();
3716     double pause_start_sec = os::elapsedTime();
3717     g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3718     log_gc_header();
3719 
3720     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3721     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3722 
3723     // If the secondary_free_list is not empty, append it to the
3724     // free_list. No need to wait for the cleanup operation to finish;
3725     // the region allocation code will check the secondary_free_list
3726     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3727     // set, skip this step so that the region allocation code has to
3728     // get entries from the secondary_free_list.
3729     if (!G1StressConcRegionFreeing) {
3730       append_secondary_free_list_if_not_empty_with_lock();
3731     }
3732 
3733     assert(check_young_list_well_formed(), "young list should be well formed");
3734 
3735     // Don't dynamically change the number of GC threads this early.  A value of
3736     // 0 is used to indicate serial work.  When parallel work is done,
3737     // it will be set.
3738 
3739     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3740       IsGCActiveMark x;
3741 
3742       gc_prologue(false);
3743       increment_total_collections(false /* full gc */);
3744       increment_gc_time_stamp();
3745 
3746       verify_before_gc();
3747 
3748       check_bitmaps("GC Start");
3749 
3750       COMPILER2_PRESENT(DerivedPointerTable::clear());
3751 
3752       // Please see comment in g1CollectedHeap.hpp and
3753       // G1CollectedHeap::ref_processing_init() to see how
3754       // reference processing currently works in G1.
3755 
3756       // Enable discovery in the STW reference processor
3757       ref_processor_stw()->enable_discovery();
3758 
3759       {
3760         // We want to temporarily turn off discovery by the
3761         // CM ref processor, if necessary, and turn it back on
3762         // on again later if we do. Using a scoped
3763         // NoRefDiscovery object will do this.
3764         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3765 
3766         // Forget the current alloc region (we might even choose it to be part
3767         // of the collection set!).
3768         _allocator->release_mutator_alloc_region();
3769 
3770         // We should call this after we retire the mutator alloc
3771         // region(s) so that all the ALLOC / RETIRE events are generated
3772         // before the start GC event.
3773         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3774 
3775         // This timing is only used by the ergonomics to handle our pause target.
3776         // It is unclear why this should not include the full pause. We will
3777         // investigate this in CR 7178365.
3778         //
3779         // Preserving the old comment here if that helps the investigation:
3780         //
3781         // The elapsed time induced by the start time below deliberately elides
3782         // the possible verification above.
3783         double sample_start_time_sec = os::elapsedTime();
3784 
3785 #if YOUNG_LIST_VERBOSE
3786         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3787         _young_list->print();
3788         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3789 #endif // YOUNG_LIST_VERBOSE
3790 
3791         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3792 
3793         double scan_wait_start = os::elapsedTime();
3794         // We have to wait until the CM threads finish scanning the
3795         // root regions as it's the only way to ensure that all the
3796         // objects on them have been correctly scanned before we start
3797         // moving them during the GC.
3798         bool waited = _cm->root_regions()->wait_until_scan_finished();
3799         double wait_time_ms = 0.0;
3800         if (waited) {
3801           double scan_wait_end = os::elapsedTime();
3802           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3803         }
3804         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3805 
3806 #if YOUNG_LIST_VERBOSE
3807         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3808         _young_list->print();
3809 #endif // YOUNG_LIST_VERBOSE
3810 
3811         if (g1_policy()->during_initial_mark_pause()) {
3812           concurrent_mark()->checkpointRootsInitialPre();
3813         }
3814 
3815 #if YOUNG_LIST_VERBOSE
3816         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3817         _young_list->print();
3818         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3819 #endif // YOUNG_LIST_VERBOSE
3820 
3821         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3822 
3823         register_humongous_regions_with_cset();
3824 
3825         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3826 
3827         _cm->note_start_of_gc();
3828         // We should not verify the per-thread SATB buffers given that
3829         // we have not filtered them yet (we'll do so during the
3830         // GC). We also call this after finalize_cset() to
3831         // ensure that the CSet has been finalized.
3832         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3833                                  true  /* verify_enqueued_buffers */,
3834                                  false /* verify_thread_buffers */,
3835                                  true  /* verify_fingers */);
3836 
3837         if (_hr_printer.is_active()) {
3838           HeapRegion* hr = g1_policy()->collection_set();
3839           while (hr != NULL) {
3840             _hr_printer.cset(hr);
3841             hr = hr->next_in_collection_set();
3842           }
3843         }
3844 
3845 #ifdef ASSERT
3846         VerifyCSetClosure cl;
3847         collection_set_iterate(&cl);
3848 #endif // ASSERT
3849 
3850         setup_surviving_young_words();
3851 
3852         // Initialize the GC alloc regions.
3853         _allocator->init_gc_alloc_regions(evacuation_info);
3854 
3855         // Actually do the work...
3856         evacuate_collection_set(evacuation_info);
3857 
3858         // We do this to mainly verify the per-thread SATB buffers
3859         // (which have been filtered by now) since we didn't verify
3860         // them earlier. No point in re-checking the stacks / enqueued
3861         // buffers given that the CSet has not changed since last time
3862         // we checked.
3863         _cm->verify_no_cset_oops(false /* verify_stacks */,
3864                                  false /* verify_enqueued_buffers */,
3865                                  true  /* verify_thread_buffers */,
3866                                  true  /* verify_fingers */);
3867 
3868         free_collection_set(g1_policy()->collection_set(), evacuation_info);
3869 
3870         eagerly_reclaim_humongous_regions();
3871 
3872         g1_policy()->clear_collection_set();
3873 
3874         cleanup_surviving_young_words();
3875 
3876         // Start a new incremental collection set for the next pause.
3877         g1_policy()->start_incremental_cset_building();
3878 
3879         clear_cset_fast_test();
3880 
3881         _young_list->reset_sampled_info();
3882 
3883         // Don't check the whole heap at this point as the
3884         // GC alloc regions from this pause have been tagged
3885         // as survivors and moved on to the survivor list.
3886         // Survivor regions will fail the !is_young() check.
3887         assert(check_young_list_empty(false /* check_heap */),
3888           "young list should be empty");
3889 
3890 #if YOUNG_LIST_VERBOSE
3891         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3892         _young_list->print();
3893 #endif // YOUNG_LIST_VERBOSE
3894 
3895         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3896                                              _young_list->first_survivor_region(),
3897                                              _young_list->last_survivor_region());
3898 
3899         _young_list->reset_auxilary_lists();
3900 
3901         if (evacuation_failed()) {
3902           _allocator->set_used(recalculate_used());
3903           uint n_queues = MAX2((int)ParallelGCThreads, 1);
3904           for (uint i = 0; i < n_queues; i++) {
3905             if (_evacuation_failed_info_array[i].has_failed()) {
3906               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3907             }
3908           }
3909         } else {
3910           // The "used" of the the collection set have already been subtracted
3911           // when they were freed.  Add in the bytes evacuated.
3912           _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3913         }
3914 
3915         if (g1_policy()->during_initial_mark_pause()) {
3916           // We have to do this before we notify the CM threads that
3917           // they can start working to make sure that all the
3918           // appropriate initialization is done on the CM object.
3919           concurrent_mark()->checkpointRootsInitialPost();
3920           set_marking_started();
3921           // Note that we don't actually trigger the CM thread at
3922           // this point. We do that later when we're sure that
3923           // the current thread has completed its logging output.
3924         }
3925 
3926         allocate_dummy_regions();
3927 
3928 #if YOUNG_LIST_VERBOSE
3929         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3930         _young_list->print();
3931         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3932 #endif // YOUNG_LIST_VERBOSE
3933 
3934         _allocator->init_mutator_alloc_region();
3935 
3936         {
3937           size_t expand_bytes = g1_policy()->expansion_amount();
3938           if (expand_bytes > 0) {
3939             size_t bytes_before = capacity();
3940             // No need for an ergo verbose message here,
3941             // expansion_amount() does this when it returns a value > 0.
3942             if (!expand(expand_bytes)) {
3943               // We failed to expand the heap. Cannot do anything about it.
3944             }
3945           }
3946         }
3947 
3948         // We redo the verification but now wrt to the new CSet which
3949         // has just got initialized after the previous CSet was freed.
3950         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3951                                  true  /* verify_enqueued_buffers */,
3952                                  true  /* verify_thread_buffers */,
3953                                  true  /* verify_fingers */);
3954         _cm->note_end_of_gc();
3955 
3956         // This timing is only used by the ergonomics to handle our pause target.
3957         // It is unclear why this should not include the full pause. We will
3958         // investigate this in CR 7178365.
3959         double sample_end_time_sec = os::elapsedTime();
3960         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3961         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3962 
3963         MemoryService::track_memory_usage();
3964 
3965         // In prepare_for_verify() below we'll need to scan the deferred
3966         // update buffers to bring the RSets up-to-date if
3967         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3968         // the update buffers we'll probably need to scan cards on the
3969         // regions we just allocated to (i.e., the GC alloc
3970         // regions). However, during the last GC we called
3971         // set_saved_mark() on all the GC alloc regions, so card
3972         // scanning might skip the [saved_mark_word()...top()] area of
3973         // those regions (i.e., the area we allocated objects into
3974         // during the last GC). But it shouldn't. Given that
3975         // saved_mark_word() is conditional on whether the GC time stamp
3976         // on the region is current or not, by incrementing the GC time
3977         // stamp here we invalidate all the GC time stamps on all the
3978         // regions and saved_mark_word() will simply return top() for
3979         // all the regions. This is a nicer way of ensuring this rather
3980         // than iterating over the regions and fixing them. In fact, the
3981         // GC time stamp increment here also ensures that
3982         // saved_mark_word() will return top() between pauses, i.e.,
3983         // during concurrent refinement. So we don't need the
3984         // is_gc_active() check to decided which top to use when
3985         // scanning cards (see CR 7039627).
3986         increment_gc_time_stamp();
3987 
3988         verify_after_gc();
3989         check_bitmaps("GC End");
3990 
3991         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3992         ref_processor_stw()->verify_no_references_recorded();
3993 
3994         // CM reference discovery will be re-enabled if necessary.
3995       }
3996 
3997       // We should do this after we potentially expand the heap so
3998       // that all the COMMIT events are generated before the end GC
3999       // event, and after we retire the GC alloc regions so that all
4000       // RETIRE events are generated before the end GC event.
4001       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4002 
4003 #ifdef TRACESPINNING
4004       ParallelTaskTerminator::print_termination_counts();
4005 #endif
4006 
4007       gc_epilogue(false);
4008     }
4009 
4010     // Print the remainder of the GC log output.
4011     log_gc_footer(os::elapsedTime() - pause_start_sec);
4012 
4013     // It is not yet to safe to tell the concurrent mark to
4014     // start as we have some optional output below. We don't want the
4015     // output from the concurrent mark thread interfering with this
4016     // logging output either.
4017 
4018     _hrm.verify_optional();
4019     verify_region_sets_optional();
4020 
4021     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4022     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4023 
4024     print_heap_after_gc();
4025     trace_heap_after_gc(_gc_tracer_stw);
4026 
4027     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4028     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4029     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4030     // before any GC notifications are raised.
4031     g1mm()->update_sizes();
4032 
4033     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4034     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4035     _gc_timer_stw->register_gc_end();
4036     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4037   }
4038   // It should now be safe to tell the concurrent mark thread to start
4039   // without its logging output interfering with the logging output
4040   // that came from the pause.
4041 
4042   if (should_start_conc_mark) {
4043     // CAUTION: after the doConcurrentMark() call below,
4044     // the concurrent marking thread(s) could be running
4045     // concurrently with us. Make sure that anything after
4046     // this point does not assume that we are the only GC thread
4047     // running. Note: of course, the actual marking work will
4048     // not start until the safepoint itself is released in
4049     // SuspendibleThreadSet::desynchronize().
4050     doConcurrentMark();
4051   }
4052 
4053   return true;
4054 }
4055 
4056 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4057   _drain_in_progress = false;
4058   set_evac_failure_closure(cl);
4059   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4060 }
4061 
4062 void G1CollectedHeap::finalize_for_evac_failure() {
4063   assert(_evac_failure_scan_stack != NULL &&
4064          _evac_failure_scan_stack->length() == 0,
4065          "Postcondition");
4066   assert(!_drain_in_progress, "Postcondition");
4067   delete _evac_failure_scan_stack;
4068   _evac_failure_scan_stack = NULL;
4069 }
4070 
4071 void G1CollectedHeap::remove_self_forwarding_pointers() {
4072   double remove_self_forwards_start = os::elapsedTime();
4073 
4074   set_par_threads();
4075   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4076   workers()->run_task(&rsfp_task);
4077   set_par_threads(0);
4078 
4079   // Now restore saved marks, if any.
4080   assert(_objs_with_preserved_marks.size() ==
4081             _preserved_marks_of_objs.size(), "Both or none.");
4082   while (!_objs_with_preserved_marks.is_empty()) {
4083     oop obj = _objs_with_preserved_marks.pop();
4084     markOop m = _preserved_marks_of_objs.pop();
4085     obj->set_mark(m);
4086   }
4087   _objs_with_preserved_marks.clear(true);
4088   _preserved_marks_of_objs.clear(true);
4089 
4090   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4091 }
4092 
4093 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4094   _evac_failure_scan_stack->push(obj);
4095 }
4096 
4097 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4098   assert(_evac_failure_scan_stack != NULL, "precondition");
4099 
4100   while (_evac_failure_scan_stack->length() > 0) {
4101      oop obj = _evac_failure_scan_stack->pop();
4102      _evac_failure_closure->set_region(heap_region_containing(obj));
4103      obj->oop_iterate_backwards(_evac_failure_closure);
4104   }
4105 }
4106 
4107 oop
4108 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4109                                                oop old) {
4110   assert(obj_in_cs(old),
4111          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4112                  (HeapWord*) old));
4113   markOop m = old->mark();
4114   oop forward_ptr = old->forward_to_atomic(old);
4115   if (forward_ptr == NULL) {
4116     // Forward-to-self succeeded.
4117     assert(_par_scan_state != NULL, "par scan state");
4118     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4119     uint queue_num = _par_scan_state->queue_num();
4120 
4121     _evacuation_failed = true;
4122     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4123     if (_evac_failure_closure != cl) {
4124       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4125       assert(!_drain_in_progress,
4126              "Should only be true while someone holds the lock.");
4127       // Set the global evac-failure closure to the current thread's.
4128       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4129       set_evac_failure_closure(cl);
4130       // Now do the common part.
4131       handle_evacuation_failure_common(old, m);
4132       // Reset to NULL.
4133       set_evac_failure_closure(NULL);
4134     } else {
4135       // The lock is already held, and this is recursive.
4136       assert(_drain_in_progress, "This should only be the recursive case.");
4137       handle_evacuation_failure_common(old, m);
4138     }
4139     return old;
4140   } else {
4141     // Forward-to-self failed. Either someone else managed to allocate
4142     // space for this object (old != forward_ptr) or they beat us in
4143     // self-forwarding it (old == forward_ptr).
4144     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4145            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4146                    "should not be in the CSet",
4147                    (HeapWord*) old, (HeapWord*) forward_ptr));
4148     return forward_ptr;
4149   }
4150 }
4151 
4152 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4153   preserve_mark_if_necessary(old, m);
4154 
4155   HeapRegion* r = heap_region_containing(old);
4156   if (!r->evacuation_failed()) {
4157     r->set_evacuation_failed(true);
4158     _hr_printer.evac_failure(r);
4159   }
4160 
4161   push_on_evac_failure_scan_stack(old);
4162 
4163   if (!_drain_in_progress) {
4164     // prevent recursion in copy_to_survivor_space()
4165     _drain_in_progress = true;
4166     drain_evac_failure_scan_stack();
4167     _drain_in_progress = false;
4168   }
4169 }
4170 
4171 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4172   assert(evacuation_failed(), "Oversaving!");
4173   // We want to call the "for_promotion_failure" version only in the
4174   // case of a promotion failure.
4175   if (m->must_be_preserved_for_promotion_failure(obj)) {
4176     _objs_with_preserved_marks.push(obj);
4177     _preserved_marks_of_objs.push(m);
4178   }
4179 }
4180 
4181 void G1ParCopyHelper::mark_object(oop obj) {
4182   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4183 
4184   // We know that the object is not moving so it's safe to read its size.
4185   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4186 }
4187 
4188 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4189   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4190   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4191   assert(from_obj != to_obj, "should not be self-forwarded");
4192 
4193   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4194   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4195 
4196   // The object might be in the process of being copied by another
4197   // worker so we cannot trust that its to-space image is
4198   // well-formed. So we have to read its size from its from-space
4199   // image which we know should not be changing.
4200   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4201 }
4202 
4203 template <class T>
4204 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4205   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4206     _scanned_klass->record_modified_oops();
4207   }
4208 }
4209 
4210 template <G1Barrier barrier, G1Mark do_mark_object>
4211 template <class T>
4212 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4213   T heap_oop = oopDesc::load_heap_oop(p);
4214 
4215   if (oopDesc::is_null(heap_oop)) {
4216     return;
4217   }
4218 
4219   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4220 
4221   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4222 
4223   const InCSetState state = _g1->in_cset_state(obj);
4224   if (state.is_in_cset()) {
4225     oop forwardee;
4226     markOop m = obj->mark();
4227     if (m->is_marked()) {
4228       forwardee = (oop) m->decode_pointer();
4229     } else {
4230       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4231     }
4232     assert(forwardee != NULL, "forwardee should not be NULL");
4233     oopDesc::encode_store_heap_oop(p, forwardee);
4234     if (do_mark_object != G1MarkNone && forwardee != obj) {
4235       // If the object is self-forwarded we don't need to explicitly
4236       // mark it, the evacuation failure protocol will do so.
4237       mark_forwarded_object(obj, forwardee);
4238     }
4239 
4240     if (barrier == G1BarrierKlass) {
4241       do_klass_barrier(p, forwardee);
4242     }
4243   } else {
4244     if (state.is_humongous()) {
4245       _g1->set_humongous_is_live(obj);
4246     }
4247     // The object is not in collection set. If we're a root scanning
4248     // closure during an initial mark pause then attempt to mark the object.
4249     if (do_mark_object == G1MarkFromRoot) {
4250       mark_object(obj);
4251     }
4252   }
4253 
4254   if (barrier == G1BarrierEvac) {
4255     _par_scan_state->update_rs(_from, p, _worker_id);
4256   }
4257 }
4258 
4259 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4260 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4261 
4262 class G1ParEvacuateFollowersClosure : public VoidClosure {
4263 protected:
4264   G1CollectedHeap*              _g1h;
4265   G1ParScanThreadState*         _par_scan_state;
4266   RefToScanQueueSet*            _queues;
4267   ParallelTaskTerminator*       _terminator;
4268 
4269   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4270   RefToScanQueueSet*      queues()         { return _queues; }
4271   ParallelTaskTerminator* terminator()     { return _terminator; }
4272 
4273 public:
4274   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4275                                 G1ParScanThreadState* par_scan_state,
4276                                 RefToScanQueueSet* queues,
4277                                 ParallelTaskTerminator* terminator)
4278     : _g1h(g1h), _par_scan_state(par_scan_state),
4279       _queues(queues), _terminator(terminator) {}
4280 
4281   void do_void();
4282 
4283 private:
4284   inline bool offer_termination();
4285 };
4286 
4287 bool G1ParEvacuateFollowersClosure::offer_termination() {
4288   G1ParScanThreadState* const pss = par_scan_state();
4289   pss->start_term_time();
4290   const bool res = terminator()->offer_termination();
4291   pss->end_term_time();
4292   return res;
4293 }
4294 
4295 void G1ParEvacuateFollowersClosure::do_void() {
4296   G1ParScanThreadState* const pss = par_scan_state();
4297   pss->trim_queue();
4298   do {
4299     pss->steal_and_trim_queue(queues());
4300   } while (!offer_termination());
4301 }
4302 
4303 class G1KlassScanClosure : public KlassClosure {
4304  G1ParCopyHelper* _closure;
4305  bool             _process_only_dirty;
4306  int              _count;
4307  public:
4308   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4309       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4310   void do_klass(Klass* klass) {
4311     // If the klass has not been dirtied we know that there's
4312     // no references into  the young gen and we can skip it.
4313    if (!_process_only_dirty || klass->has_modified_oops()) {
4314       // Clean the klass since we're going to scavenge all the metadata.
4315       klass->clear_modified_oops();
4316 
4317       // Tell the closure that this klass is the Klass to scavenge
4318       // and is the one to dirty if oops are left pointing into the young gen.
4319       _closure->set_scanned_klass(klass);
4320 
4321       klass->oops_do(_closure);
4322 
4323       _closure->set_scanned_klass(NULL);
4324     }
4325     _count++;
4326   }
4327 };
4328 
4329 class G1ParTask : public AbstractGangTask {
4330 protected:
4331   G1CollectedHeap*       _g1h;
4332   RefToScanQueueSet      *_queues;
4333   G1RootProcessor*       _root_processor;
4334   ParallelTaskTerminator _terminator;
4335   uint _n_workers;
4336 
4337   Mutex _stats_lock;
4338   Mutex* stats_lock() { return &_stats_lock; }
4339 
4340 public:
4341   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4342     : AbstractGangTask("G1 collection"),
4343       _g1h(g1h),
4344       _queues(task_queues),
4345       _root_processor(root_processor),
4346       _terminator(0, _queues),
4347       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4348   {}
4349 
4350   RefToScanQueueSet* queues() { return _queues; }
4351 
4352   RefToScanQueue *work_queue(int i) {
4353     return queues()->queue(i);
4354   }
4355 
4356   ParallelTaskTerminator* terminator() { return &_terminator; }
4357 
4358   virtual void set_for_termination(int active_workers) {
4359     _root_processor->set_num_workers(active_workers);
4360     terminator()->reset_for_reuse(active_workers);
4361     _n_workers = active_workers;
4362   }
4363 
4364   // Helps out with CLD processing.
4365   //
4366   // During InitialMark we need to:
4367   // 1) Scavenge all CLDs for the young GC.
4368   // 2) Mark all objects directly reachable from strong CLDs.
4369   template <G1Mark do_mark_object>
4370   class G1CLDClosure : public CLDClosure {
4371     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4372     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4373     G1KlassScanClosure                                _klass_in_cld_closure;
4374     bool                                              _claim;
4375 
4376    public:
4377     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4378                  bool only_young, bool claim)
4379         : _oop_closure(oop_closure),
4380           _oop_in_klass_closure(oop_closure->g1(),
4381                                 oop_closure->pss(),
4382                                 oop_closure->rp()),
4383           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4384           _claim(claim) {
4385 
4386     }
4387 
4388     void do_cld(ClassLoaderData* cld) {
4389       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4390     }
4391   };
4392 
4393   void work(uint worker_id) {
4394     if (worker_id >= _n_workers) return;  // no work needed this round
4395 
4396     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4397 
4398     {
4399       ResourceMark rm;
4400       HandleMark   hm;
4401 
4402       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4403 
4404       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4405       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4406 
4407       pss.set_evac_failure_closure(&evac_failure_cl);
4408 
4409       bool only_young = _g1h->g1_policy()->gcs_are_young();
4410 
4411       // Non-IM young GC.
4412       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4413       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4414                                                                                only_young, // Only process dirty klasses.
4415                                                                                false);     // No need to claim CLDs.
4416       // IM young GC.
4417       //    Strong roots closures.
4418       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4419       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4420                                                                                false, // Process all klasses.
4421                                                                                true); // Need to claim CLDs.
4422       //    Weak roots closures.
4423       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4424       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4425                                                                                     false, // Process all klasses.
4426                                                                                     true); // Need to claim CLDs.
4427 
4428       OopClosure* strong_root_cl;
4429       OopClosure* weak_root_cl;
4430       CLDClosure* strong_cld_cl;
4431       CLDClosure* weak_cld_cl;
4432 
4433       bool trace_metadata = false;
4434 
4435       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4436         // We also need to mark copied objects.
4437         strong_root_cl = &scan_mark_root_cl;
4438         strong_cld_cl  = &scan_mark_cld_cl;
4439         if (ClassUnloadingWithConcurrentMark) {
4440           weak_root_cl = &scan_mark_weak_root_cl;
4441           weak_cld_cl  = &scan_mark_weak_cld_cl;
4442           trace_metadata = true;
4443         } else {
4444           weak_root_cl = &scan_mark_root_cl;
4445           weak_cld_cl  = &scan_mark_cld_cl;
4446         }
4447       } else {
4448         strong_root_cl = &scan_only_root_cl;
4449         weak_root_cl   = &scan_only_root_cl;
4450         strong_cld_cl  = &scan_only_cld_cl;
4451         weak_cld_cl    = &scan_only_cld_cl;
4452       }
4453 
4454       pss.start_strong_roots();
4455 
4456       _root_processor->evacuate_roots(strong_root_cl,
4457                                       weak_root_cl,
4458                                       strong_cld_cl,
4459                                       weak_cld_cl,
4460                                       trace_metadata,
4461                                       worker_id);
4462 
4463       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4464       _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4465                                             weak_root_cl,
4466                                             worker_id);
4467       pss.end_strong_roots();
4468 
4469       {
4470         double start = os::elapsedTime();
4471         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4472         evac.do_void();
4473         double elapsed_sec = os::elapsedTime() - start;
4474         double term_sec = pss.term_time();
4475         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4476         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4477         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4478       }
4479       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4480       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4481 
4482       if (PrintTerminationStats) {
4483         MutexLocker x(stats_lock());
4484         pss.print_termination_stats(worker_id);
4485       }
4486 
4487       assert(pss.queue_is_empty(), "should be empty");
4488 
4489       // Close the inner scope so that the ResourceMark and HandleMark
4490       // destructors are executed here and are included as part of the
4491       // "GC Worker Time".
4492     }
4493     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4494   }
4495 };
4496 
4497 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4498 private:
4499   BoolObjectClosure* _is_alive;
4500   int _initial_string_table_size;
4501   int _initial_symbol_table_size;
4502 
4503   bool  _process_strings;
4504   int _strings_processed;
4505   int _strings_removed;
4506 
4507   bool  _process_symbols;
4508   int _symbols_processed;
4509   int _symbols_removed;
4510 
4511 public:
4512   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4513     AbstractGangTask("String/Symbol Unlinking"),
4514     _is_alive(is_alive),
4515     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4516     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4517 
4518     _initial_string_table_size = StringTable::the_table()->table_size();
4519     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4520     if (process_strings) {
4521       StringTable::clear_parallel_claimed_index();
4522     }
4523     if (process_symbols) {
4524       SymbolTable::clear_parallel_claimed_index();
4525     }
4526   }
4527 
4528   ~G1StringSymbolTableUnlinkTask() {
4529     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4530               err_msg("claim value %d after unlink less than initial string table size %d",
4531                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4532     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4533               err_msg("claim value %d after unlink less than initial symbol table size %d",
4534                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4535 
4536     if (G1TraceStringSymbolTableScrubbing) {
4537       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4538                              "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4539                              "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4540                              strings_processed(), strings_removed(),
4541                              symbols_processed(), symbols_removed());
4542     }
4543   }
4544 
4545   void work(uint worker_id) {
4546     int strings_processed = 0;
4547     int strings_removed = 0;
4548     int symbols_processed = 0;
4549     int symbols_removed = 0;
4550     if (_process_strings) {
4551       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4552       Atomic::add(strings_processed, &_strings_processed);
4553       Atomic::add(strings_removed, &_strings_removed);
4554     }
4555     if (_process_symbols) {
4556       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4557       Atomic::add(symbols_processed, &_symbols_processed);
4558       Atomic::add(symbols_removed, &_symbols_removed);
4559     }
4560   }
4561 
4562   size_t strings_processed() const { return (size_t)_strings_processed; }
4563   size_t strings_removed()   const { return (size_t)_strings_removed; }
4564 
4565   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4566   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4567 };
4568 
4569 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4570 private:
4571   static Monitor* _lock;
4572 
4573   BoolObjectClosure* const _is_alive;
4574   const bool               _unloading_occurred;
4575   const uint               _num_workers;
4576 
4577   // Variables used to claim nmethods.
4578   nmethod* _first_nmethod;
4579   volatile nmethod* _claimed_nmethod;
4580 
4581   // The list of nmethods that need to be processed by the second pass.
4582   volatile nmethod* _postponed_list;
4583   volatile uint     _num_entered_barrier;
4584 
4585  public:
4586   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4587       _is_alive(is_alive),
4588       _unloading_occurred(unloading_occurred),
4589       _num_workers(num_workers),
4590       _first_nmethod(NULL),
4591       _claimed_nmethod(NULL),
4592       _postponed_list(NULL),
4593       _num_entered_barrier(0)
4594   {
4595     nmethod::increase_unloading_clock();
4596     // Get first alive nmethod
4597     NMethodIterator iter = NMethodIterator();
4598     if(iter.next_alive()) {
4599       _first_nmethod = iter.method();
4600     }
4601     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4602   }
4603 
4604   ~G1CodeCacheUnloadingTask() {
4605     CodeCache::verify_clean_inline_caches();
4606 
4607     CodeCache::set_needs_cache_clean(false);
4608     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4609 
4610     CodeCache::verify_icholder_relocations();
4611   }
4612 
4613  private:
4614   void add_to_postponed_list(nmethod* nm) {
4615       nmethod* old;
4616       do {
4617         old = (nmethod*)_postponed_list;
4618         nm->set_unloading_next(old);
4619       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4620   }
4621 
4622   void clean_nmethod(nmethod* nm) {
4623     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4624 
4625     if (postponed) {
4626       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4627       add_to_postponed_list(nm);
4628     }
4629 
4630     // Mark that this thread has been cleaned/unloaded.
4631     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4632     nm->set_unloading_clock(nmethod::global_unloading_clock());
4633   }
4634 
4635   void clean_nmethod_postponed(nmethod* nm) {
4636     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4637   }
4638 
4639   static const int MaxClaimNmethods = 16;
4640 
4641   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4642     nmethod* first;
4643     NMethodIterator last;
4644 
4645     do {
4646       *num_claimed_nmethods = 0;
4647 
4648       first = (nmethod*)_claimed_nmethod;
4649       last = NMethodIterator(first);
4650 
4651       if (first != NULL) {
4652 
4653         for (int i = 0; i < MaxClaimNmethods; i++) {
4654           if (!last.next_alive()) {
4655             break;
4656           }
4657           claimed_nmethods[i] = last.method();
4658           (*num_claimed_nmethods)++;
4659         }
4660       }
4661 
4662     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4663   }
4664 
4665   nmethod* claim_postponed_nmethod() {
4666     nmethod* claim;
4667     nmethod* next;
4668 
4669     do {
4670       claim = (nmethod*)_postponed_list;
4671       if (claim == NULL) {
4672         return NULL;
4673       }
4674 
4675       next = claim->unloading_next();
4676 
4677     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4678 
4679     return claim;
4680   }
4681 
4682  public:
4683   // Mark that we're done with the first pass of nmethod cleaning.
4684   void barrier_mark(uint worker_id) {
4685     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4686     _num_entered_barrier++;
4687     if (_num_entered_barrier == _num_workers) {
4688       ml.notify_all();
4689     }
4690   }
4691 
4692   // See if we have to wait for the other workers to
4693   // finish their first-pass nmethod cleaning work.
4694   void barrier_wait(uint worker_id) {
4695     if (_num_entered_barrier < _num_workers) {
4696       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4697       while (_num_entered_barrier < _num_workers) {
4698           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4699       }
4700     }
4701   }
4702 
4703   // Cleaning and unloading of nmethods. Some work has to be postponed
4704   // to the second pass, when we know which nmethods survive.
4705   void work_first_pass(uint worker_id) {
4706     // The first nmethods is claimed by the first worker.
4707     if (worker_id == 0 && _first_nmethod != NULL) {
4708       clean_nmethod(_first_nmethod);
4709       _first_nmethod = NULL;
4710     }
4711 
4712     int num_claimed_nmethods;
4713     nmethod* claimed_nmethods[MaxClaimNmethods];
4714 
4715     while (true) {
4716       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4717 
4718       if (num_claimed_nmethods == 0) {
4719         break;
4720       }
4721 
4722       for (int i = 0; i < num_claimed_nmethods; i++) {
4723         clean_nmethod(claimed_nmethods[i]);
4724       }
4725     }
4726   }
4727 
4728   void work_second_pass(uint worker_id) {
4729     nmethod* nm;
4730     // Take care of postponed nmethods.
4731     while ((nm = claim_postponed_nmethod()) != NULL) {
4732       clean_nmethod_postponed(nm);
4733     }
4734   }
4735 };
4736 
4737 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4738 
4739 class G1KlassCleaningTask : public StackObj {
4740   BoolObjectClosure*                      _is_alive;
4741   volatile jint                           _clean_klass_tree_claimed;
4742   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4743 
4744  public:
4745   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4746       _is_alive(is_alive),
4747       _clean_klass_tree_claimed(0),
4748       _klass_iterator() {
4749   }
4750 
4751  private:
4752   bool claim_clean_klass_tree_task() {
4753     if (_clean_klass_tree_claimed) {
4754       return false;
4755     }
4756 
4757     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4758   }
4759 
4760   InstanceKlass* claim_next_klass() {
4761     Klass* klass;
4762     do {
4763       klass =_klass_iterator.next_klass();
4764     } while (klass != NULL && !klass->oop_is_instance());
4765 
4766     return (InstanceKlass*)klass;
4767   }
4768 
4769 public:
4770 
4771   void clean_klass(InstanceKlass* ik) {
4772     ik->clean_implementors_list(_is_alive);
4773     ik->clean_method_data(_is_alive);
4774 
4775     // G1 specific cleanup work that has
4776     // been moved here to be done in parallel.
4777     ik->clean_dependent_nmethods();
4778   }
4779 
4780   void work() {
4781     ResourceMark rm;
4782 
4783     // One worker will clean the subklass/sibling klass tree.
4784     if (claim_clean_klass_tree_task()) {
4785       Klass::clean_subklass_tree(_is_alive);
4786     }
4787 
4788     // All workers will help cleaning the classes,
4789     InstanceKlass* klass;
4790     while ((klass = claim_next_klass()) != NULL) {
4791       clean_klass(klass);
4792     }
4793   }
4794 };
4795 
4796 // To minimize the remark pause times, the tasks below are done in parallel.
4797 class G1ParallelCleaningTask : public AbstractGangTask {
4798 private:
4799   G1StringSymbolTableUnlinkTask _string_symbol_task;
4800   G1CodeCacheUnloadingTask      _code_cache_task;
4801   G1KlassCleaningTask           _klass_cleaning_task;
4802 
4803 public:
4804   // The constructor is run in the VMThread.
4805   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4806       AbstractGangTask("Parallel Cleaning"),
4807       _string_symbol_task(is_alive, process_strings, process_symbols),
4808       _code_cache_task(num_workers, is_alive, unloading_occurred),
4809       _klass_cleaning_task(is_alive) {
4810   }
4811 
4812   // The parallel work done by all worker threads.
4813   void work(uint worker_id) {
4814     // Do first pass of code cache cleaning.
4815     _code_cache_task.work_first_pass(worker_id);
4816 
4817     // Let the threads mark that the first pass is done.
4818     _code_cache_task.barrier_mark(worker_id);
4819 
4820     // Clean the Strings and Symbols.
4821     _string_symbol_task.work(worker_id);
4822 
4823     // Wait for all workers to finish the first code cache cleaning pass.
4824     _code_cache_task.barrier_wait(worker_id);
4825 
4826     // Do the second code cache cleaning work, which realize on
4827     // the liveness information gathered during the first pass.
4828     _code_cache_task.work_second_pass(worker_id);
4829 
4830     // Clean all klasses that were not unloaded.
4831     _klass_cleaning_task.work();
4832   }
4833 };
4834 
4835 
4836 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4837                                         bool process_strings,
4838                                         bool process_symbols,
4839                                         bool class_unloading_occurred) {
4840   uint n_workers = workers()->active_workers();
4841 
4842   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4843                                         n_workers, class_unloading_occurred);
4844   set_par_threads(n_workers);
4845   workers()->run_task(&g1_unlink_task);
4846   set_par_threads(0);
4847 }
4848 
4849 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4850                                                      bool process_strings, bool process_symbols) {
4851   {
4852     uint n_workers = _g1h->workers()->active_workers();
4853     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4854     set_par_threads(n_workers);
4855     workers()->run_task(&g1_unlink_task);
4856     set_par_threads(0);
4857   }
4858 
4859   if (G1StringDedup::is_enabled()) {
4860     G1StringDedup::unlink(is_alive);
4861   }
4862 }
4863 
4864 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4865  private:
4866   DirtyCardQueueSet* _queue;
4867  public:
4868   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4869 
4870   virtual void work(uint worker_id) {
4871     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4872     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4873 
4874     RedirtyLoggedCardTableEntryClosure cl;
4875     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4876 
4877     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4878   }
4879 };
4880 
4881 void G1CollectedHeap::redirty_logged_cards() {
4882   double redirty_logged_cards_start = os::elapsedTime();
4883 
4884   uint n_workers = _g1h->workers()->active_workers();
4885 
4886   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4887   dirty_card_queue_set().reset_for_par_iteration();
4888   set_par_threads(n_workers);
4889   workers()->run_task(&redirty_task);
4890   set_par_threads(0);
4891 
4892   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4893   dcq.merge_bufferlists(&dirty_card_queue_set());
4894   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4895 
4896   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4897 }
4898 
4899 // Weak Reference Processing support
4900 
4901 // An always "is_alive" closure that is used to preserve referents.
4902 // If the object is non-null then it's alive.  Used in the preservation
4903 // of referent objects that are pointed to by reference objects
4904 // discovered by the CM ref processor.
4905 class G1AlwaysAliveClosure: public BoolObjectClosure {
4906   G1CollectedHeap* _g1;
4907 public:
4908   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4909   bool do_object_b(oop p) {
4910     if (p != NULL) {
4911       return true;
4912     }
4913     return false;
4914   }
4915 };
4916 
4917 bool G1STWIsAliveClosure::do_object_b(oop p) {
4918   // An object is reachable if it is outside the collection set,
4919   // or is inside and copied.
4920   return !_g1->obj_in_cs(p) || p->is_forwarded();
4921 }
4922 
4923 // Non Copying Keep Alive closure
4924 class G1KeepAliveClosure: public OopClosure {
4925   G1CollectedHeap* _g1;
4926 public:
4927   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4928   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4929   void do_oop(oop* p) {
4930     oop obj = *p;
4931     assert(obj != NULL, "the caller should have filtered out NULL values");
4932 
4933     const InCSetState cset_state = _g1->in_cset_state(obj);
4934     if (!cset_state.is_in_cset_or_humongous()) {
4935       return;
4936     }
4937     if (cset_state.is_in_cset()) {
4938       assert( obj->is_forwarded(), "invariant" );
4939       *p = obj->forwardee();
4940     } else {
4941       assert(!obj->is_forwarded(), "invariant" );
4942       assert(cset_state.is_humongous(),
4943              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4944       _g1->set_humongous_is_live(obj);
4945     }
4946   }
4947 };
4948 
4949 // Copying Keep Alive closure - can be called from both
4950 // serial and parallel code as long as different worker
4951 // threads utilize different G1ParScanThreadState instances
4952 // and different queues.
4953 
4954 class G1CopyingKeepAliveClosure: public OopClosure {
4955   G1CollectedHeap*         _g1h;
4956   OopClosure*              _copy_non_heap_obj_cl;
4957   G1ParScanThreadState*    _par_scan_state;
4958 
4959 public:
4960   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4961                             OopClosure* non_heap_obj_cl,
4962                             G1ParScanThreadState* pss):
4963     _g1h(g1h),
4964     _copy_non_heap_obj_cl(non_heap_obj_cl),
4965     _par_scan_state(pss)
4966   {}
4967 
4968   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4969   virtual void do_oop(      oop* p) { do_oop_work(p); }
4970 
4971   template <class T> void do_oop_work(T* p) {
4972     oop obj = oopDesc::load_decode_heap_oop(p);
4973 
4974     if (_g1h->is_in_cset_or_humongous(obj)) {
4975       // If the referent object has been forwarded (either copied
4976       // to a new location or to itself in the event of an
4977       // evacuation failure) then we need to update the reference
4978       // field and, if both reference and referent are in the G1
4979       // heap, update the RSet for the referent.
4980       //
4981       // If the referent has not been forwarded then we have to keep
4982       // it alive by policy. Therefore we have copy the referent.
4983       //
4984       // If the reference field is in the G1 heap then we can push
4985       // on the PSS queue. When the queue is drained (after each
4986       // phase of reference processing) the object and it's followers
4987       // will be copied, the reference field set to point to the
4988       // new location, and the RSet updated. Otherwise we need to
4989       // use the the non-heap or metadata closures directly to copy
4990       // the referent object and update the pointer, while avoiding
4991       // updating the RSet.
4992 
4993       if (_g1h->is_in_g1_reserved(p)) {
4994         _par_scan_state->push_on_queue(p);
4995       } else {
4996         assert(!Metaspace::contains((const void*)p),
4997                err_msg("Unexpectedly found a pointer from metadata: "
4998                               PTR_FORMAT, p));
4999         _copy_non_heap_obj_cl->do_oop(p);
5000       }
5001     }
5002   }
5003 };
5004 
5005 // Serial drain queue closure. Called as the 'complete_gc'
5006 // closure for each discovered list in some of the
5007 // reference processing phases.
5008 
5009 class G1STWDrainQueueClosure: public VoidClosure {
5010 protected:
5011   G1CollectedHeap* _g1h;
5012   G1ParScanThreadState* _par_scan_state;
5013 
5014   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5015 
5016 public:
5017   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5018     _g1h(g1h),
5019     _par_scan_state(pss)
5020   { }
5021 
5022   void do_void() {
5023     G1ParScanThreadState* const pss = par_scan_state();
5024     pss->trim_queue();
5025   }
5026 };
5027 
5028 // Parallel Reference Processing closures
5029 
5030 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5031 // processing during G1 evacuation pauses.
5032 
5033 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5034 private:
5035   G1CollectedHeap*   _g1h;
5036   RefToScanQueueSet* _queues;
5037   FlexibleWorkGang*  _workers;
5038   int                _active_workers;
5039 
5040 public:
5041   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5042                         FlexibleWorkGang* workers,
5043                         RefToScanQueueSet *task_queues,
5044                         int n_workers) :
5045     _g1h(g1h),
5046     _queues(task_queues),
5047     _workers(workers),
5048     _active_workers(n_workers)
5049   {
5050     assert(n_workers > 0, "shouldn't call this otherwise");
5051   }
5052 
5053   // Executes the given task using concurrent marking worker threads.
5054   virtual void execute(ProcessTask& task);
5055   virtual void execute(EnqueueTask& task);
5056 };
5057 
5058 // Gang task for possibly parallel reference processing
5059 
5060 class G1STWRefProcTaskProxy: public AbstractGangTask {
5061   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5062   ProcessTask&     _proc_task;
5063   G1CollectedHeap* _g1h;
5064   RefToScanQueueSet *_task_queues;
5065   ParallelTaskTerminator* _terminator;
5066 
5067 public:
5068   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5069                      G1CollectedHeap* g1h,
5070                      RefToScanQueueSet *task_queues,
5071                      ParallelTaskTerminator* terminator) :
5072     AbstractGangTask("Process reference objects in parallel"),
5073     _proc_task(proc_task),
5074     _g1h(g1h),
5075     _task_queues(task_queues),
5076     _terminator(terminator)
5077   {}
5078 
5079   virtual void work(uint worker_id) {
5080     // The reference processing task executed by a single worker.
5081     ResourceMark rm;
5082     HandleMark   hm;
5083 
5084     G1STWIsAliveClosure is_alive(_g1h);
5085 
5086     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5087     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5088 
5089     pss.set_evac_failure_closure(&evac_failure_cl);
5090 
5091     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5092 
5093     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5094 
5095     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5096 
5097     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5098       // We also need to mark copied objects.
5099       copy_non_heap_cl = &copy_mark_non_heap_cl;
5100     }
5101 
5102     // Keep alive closure.
5103     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5104 
5105     // Complete GC closure
5106     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5107 
5108     // Call the reference processing task's work routine.
5109     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5110 
5111     // Note we cannot assert that the refs array is empty here as not all
5112     // of the processing tasks (specifically phase2 - pp2_work) execute
5113     // the complete_gc closure (which ordinarily would drain the queue) so
5114     // the queue may not be empty.
5115   }
5116 };
5117 
5118 // Driver routine for parallel reference processing.
5119 // Creates an instance of the ref processing gang
5120 // task and has the worker threads execute it.
5121 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5122   assert(_workers != NULL, "Need parallel worker threads.");
5123 
5124   ParallelTaskTerminator terminator(_active_workers, _queues);
5125   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5126 
5127   _g1h->set_par_threads(_active_workers);
5128   _workers->run_task(&proc_task_proxy);
5129   _g1h->set_par_threads(0);
5130 }
5131 
5132 // Gang task for parallel reference enqueueing.
5133 
5134 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5135   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5136   EnqueueTask& _enq_task;
5137 
5138 public:
5139   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5140     AbstractGangTask("Enqueue reference objects in parallel"),
5141     _enq_task(enq_task)
5142   { }
5143 
5144   virtual void work(uint worker_id) {
5145     _enq_task.work(worker_id);
5146   }
5147 };
5148 
5149 // Driver routine for parallel reference enqueueing.
5150 // Creates an instance of the ref enqueueing gang
5151 // task and has the worker threads execute it.
5152 
5153 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5154   assert(_workers != NULL, "Need parallel worker threads.");
5155 
5156   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5157 
5158   _g1h->set_par_threads(_active_workers);
5159   _workers->run_task(&enq_task_proxy);
5160   _g1h->set_par_threads(0);
5161 }
5162 
5163 // End of weak reference support closures
5164 
5165 // Abstract task used to preserve (i.e. copy) any referent objects
5166 // that are in the collection set and are pointed to by reference
5167 // objects discovered by the CM ref processor.
5168 
5169 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5170 protected:
5171   G1CollectedHeap* _g1h;
5172   RefToScanQueueSet      *_queues;
5173   ParallelTaskTerminator _terminator;
5174   uint _n_workers;
5175 
5176 public:
5177   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5178     AbstractGangTask("ParPreserveCMReferents"),
5179     _g1h(g1h),
5180     _queues(task_queues),
5181     _terminator(workers, _queues),
5182     _n_workers(workers)
5183   { }
5184 
5185   void work(uint worker_id) {
5186     ResourceMark rm;
5187     HandleMark   hm;
5188 
5189     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5190     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5191 
5192     pss.set_evac_failure_closure(&evac_failure_cl);
5193 
5194     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5195 
5196     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5197 
5198     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5199 
5200     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5201 
5202     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5203       // We also need to mark copied objects.
5204       copy_non_heap_cl = &copy_mark_non_heap_cl;
5205     }
5206 
5207     // Is alive closure
5208     G1AlwaysAliveClosure always_alive(_g1h);
5209 
5210     // Copying keep alive closure. Applied to referent objects that need
5211     // to be copied.
5212     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5213 
5214     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5215 
5216     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5217     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5218 
5219     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5220     // So this must be true - but assert just in case someone decides to
5221     // change the worker ids.
5222     assert(worker_id < limit, "sanity");
5223     assert(!rp->discovery_is_atomic(), "check this code");
5224 
5225     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5226     for (uint idx = worker_id; idx < limit; idx += stride) {
5227       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5228 
5229       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5230       while (iter.has_next()) {
5231         // Since discovery is not atomic for the CM ref processor, we
5232         // can see some null referent objects.
5233         iter.load_ptrs(DEBUG_ONLY(true));
5234         oop ref = iter.obj();
5235 
5236         // This will filter nulls.
5237         if (iter.is_referent_alive()) {
5238           iter.make_referent_alive();
5239         }
5240         iter.move_to_next();
5241       }
5242     }
5243 
5244     // Drain the queue - which may cause stealing
5245     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5246     drain_queue.do_void();
5247     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5248     assert(pss.queue_is_empty(), "should be");
5249   }
5250 };
5251 
5252 // Weak Reference processing during an evacuation pause (part 1).
5253 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5254   double ref_proc_start = os::elapsedTime();
5255 
5256   ReferenceProcessor* rp = _ref_processor_stw;
5257   assert(rp->discovery_enabled(), "should have been enabled");
5258 
5259   // Any reference objects, in the collection set, that were 'discovered'
5260   // by the CM ref processor should have already been copied (either by
5261   // applying the external root copy closure to the discovered lists, or
5262   // by following an RSet entry).
5263   //
5264   // But some of the referents, that are in the collection set, that these
5265   // reference objects point to may not have been copied: the STW ref
5266   // processor would have seen that the reference object had already
5267   // been 'discovered' and would have skipped discovering the reference,
5268   // but would not have treated the reference object as a regular oop.
5269   // As a result the copy closure would not have been applied to the
5270   // referent object.
5271   //
5272   // We need to explicitly copy these referent objects - the references
5273   // will be processed at the end of remarking.
5274   //
5275   // We also need to do this copying before we process the reference
5276   // objects discovered by the STW ref processor in case one of these
5277   // referents points to another object which is also referenced by an
5278   // object discovered by the STW ref processor.
5279 
5280   assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5281 
5282   set_par_threads(no_of_gc_workers);
5283   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5284                                                  no_of_gc_workers,
5285                                                  _task_queues);
5286 
5287   workers()->run_task(&keep_cm_referents);
5288 
5289   set_par_threads(0);
5290 
5291   // Closure to test whether a referent is alive.
5292   G1STWIsAliveClosure is_alive(this);
5293 
5294   // Even when parallel reference processing is enabled, the processing
5295   // of JNI refs is serial and performed serially by the current thread
5296   // rather than by a worker. The following PSS will be used for processing
5297   // JNI refs.
5298 
5299   // Use only a single queue for this PSS.
5300   G1ParScanThreadState            pss(this, 0, NULL);
5301 
5302   // We do not embed a reference processor in the copying/scanning
5303   // closures while we're actually processing the discovered
5304   // reference objects.
5305   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5306 
5307   pss.set_evac_failure_closure(&evac_failure_cl);
5308 
5309   assert(pss.queue_is_empty(), "pre-condition");
5310 
5311   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5312 
5313   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5314 
5315   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5316 
5317   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5318     // We also need to mark copied objects.
5319     copy_non_heap_cl = &copy_mark_non_heap_cl;
5320   }
5321 
5322   // Keep alive closure.
5323   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5324 
5325   // Serial Complete GC closure
5326   G1STWDrainQueueClosure drain_queue(this, &pss);
5327 
5328   // Setup the soft refs policy...
5329   rp->setup_policy(false);
5330 
5331   ReferenceProcessorStats stats;
5332   if (!rp->processing_is_mt()) {
5333     // Serial reference processing...
5334     stats = rp->process_discovered_references(&is_alive,
5335                                               &keep_alive,
5336                                               &drain_queue,
5337                                               NULL,
5338                                               _gc_timer_stw,
5339                                               _gc_tracer_stw->gc_id());
5340   } else {
5341     // Parallel reference processing
5342     assert(rp->num_q() == no_of_gc_workers, "sanity");
5343     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5344 
5345     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5346     stats = rp->process_discovered_references(&is_alive,
5347                                               &keep_alive,
5348                                               &drain_queue,
5349                                               &par_task_executor,
5350                                               _gc_timer_stw,
5351                                               _gc_tracer_stw->gc_id());
5352   }
5353 
5354   _gc_tracer_stw->report_gc_reference_stats(stats);
5355 
5356   // We have completed copying any necessary live referent objects.
5357   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5358 
5359   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5360   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5361 }
5362 
5363 // Weak Reference processing during an evacuation pause (part 2).
5364 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5365   double ref_enq_start = os::elapsedTime();
5366 
5367   ReferenceProcessor* rp = _ref_processor_stw;
5368   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5369 
5370   // Now enqueue any remaining on the discovered lists on to
5371   // the pending list.
5372   if (!rp->processing_is_mt()) {
5373     // Serial reference processing...
5374     rp->enqueue_discovered_references();
5375   } else {
5376     // Parallel reference enqueueing
5377 
5378     assert(no_of_gc_workers == workers()->active_workers(),
5379            "Need to reset active workers");
5380     assert(rp->num_q() == no_of_gc_workers, "sanity");
5381     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5382 
5383     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5384     rp->enqueue_discovered_references(&par_task_executor);
5385   }
5386 
5387   rp->verify_no_references_recorded();
5388   assert(!rp->discovery_enabled(), "should have been disabled");
5389 
5390   // FIXME
5391   // CM's reference processing also cleans up the string and symbol tables.
5392   // Should we do that here also? We could, but it is a serial operation
5393   // and could significantly increase the pause time.
5394 
5395   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5396   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5397 }
5398 
5399 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5400   _expand_heap_after_alloc_failure = true;
5401   _evacuation_failed = false;
5402 
5403   // Should G1EvacuationFailureALot be in effect for this GC?
5404   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5405 
5406   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5407 
5408   // Disable the hot card cache.
5409   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5410   hot_card_cache->reset_hot_cache_claimed_index();
5411   hot_card_cache->set_use_cache(false);
5412 
5413   uint n_workers;
5414   n_workers =
5415     AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5416                                    workers()->active_workers(),
5417                                    Threads::number_of_non_daemon_threads());
5418   assert(UseDynamicNumberOfGCThreads ||
5419          n_workers == workers()->total_workers(),
5420          "If not dynamic should be using all the  workers");
5421   workers()->set_active_workers(n_workers);
5422   set_par_threads(n_workers);
5423 
5424 
5425   init_for_evac_failure(NULL);
5426 
5427   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5428   double start_par_time_sec = os::elapsedTime();
5429   double end_par_time_sec;
5430 
5431   {
5432     G1RootProcessor root_processor(this);
5433     G1ParTask g1_par_task(this, _task_queues, &root_processor);
5434     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5435     if (g1_policy()->during_initial_mark_pause()) {
5436       ClassLoaderDataGraph::clear_claimed_marks();
5437     }
5438 
5439      // The individual threads will set their evac-failure closures.
5440      if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5441      // These tasks use ShareHeap::_process_strong_tasks
5442      assert(UseDynamicNumberOfGCThreads ||
5443             workers()->active_workers() == workers()->total_workers(),
5444             "If not dynamic should be using all the  workers");
5445     workers()->run_task(&g1_par_task);
5446     end_par_time_sec = os::elapsedTime();
5447 
5448     // Closing the inner scope will execute the destructor
5449     // for the G1RootProcessor object. We record the current
5450     // elapsed time before closing the scope so that time
5451     // taken for the destructor is NOT included in the
5452     // reported parallel time.
5453   }
5454 
5455   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5456 
5457   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5458   phase_times->record_par_time(par_time_ms);
5459 
5460   double code_root_fixup_time_ms =
5461         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5462   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5463 
5464   set_par_threads(0);
5465 
5466   // Process any discovered reference objects - we have
5467   // to do this _before_ we retire the GC alloc regions
5468   // as we may have to copy some 'reachable' referent
5469   // objects (and their reachable sub-graphs) that were
5470   // not copied during the pause.
5471   process_discovered_references(n_workers);
5472 
5473   if (G1StringDedup::is_enabled()) {
5474     double fixup_start = os::elapsedTime();
5475 
5476     G1STWIsAliveClosure is_alive(this);
5477     G1KeepAliveClosure keep_alive(this);
5478     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5479 
5480     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5481     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5482   }
5483 
5484   _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5485   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5486 
5487   // Reset and re-enable the hot card cache.
5488   // Note the counts for the cards in the regions in the
5489   // collection set are reset when the collection set is freed.
5490   hot_card_cache->reset_hot_cache();
5491   hot_card_cache->set_use_cache(true);
5492 
5493   purge_code_root_memory();
5494 
5495   finalize_for_evac_failure();
5496 
5497   if (evacuation_failed()) {
5498     remove_self_forwarding_pointers();
5499 
5500     // Reset the G1EvacuationFailureALot counters and flags
5501     // Note: the values are reset only when an actual
5502     // evacuation failure occurs.
5503     NOT_PRODUCT(reset_evacuation_should_fail();)
5504   }
5505 
5506   // Enqueue any remaining references remaining on the STW
5507   // reference processor's discovered lists. We need to do
5508   // this after the card table is cleaned (and verified) as
5509   // the act of enqueueing entries on to the pending list
5510   // will log these updates (and dirty their associated
5511   // cards). We need these updates logged to update any
5512   // RSets.
5513   enqueue_discovered_references(n_workers);
5514 
5515   redirty_logged_cards();
5516   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5517 }
5518 
5519 void G1CollectedHeap::free_region(HeapRegion* hr,
5520                                   FreeRegionList* free_list,
5521                                   bool par,
5522                                   bool locked) {
5523   assert(!hr->is_free(), "the region should not be free");
5524   assert(!hr->is_empty(), "the region should not be empty");
5525   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5526   assert(free_list != NULL, "pre-condition");
5527 
5528   if (G1VerifyBitmaps) {
5529     MemRegion mr(hr->bottom(), hr->end());
5530     concurrent_mark()->clearRangePrevBitmap(mr);
5531   }
5532 
5533   // Clear the card counts for this region.
5534   // Note: we only need to do this if the region is not young
5535   // (since we don't refine cards in young regions).
5536   if (!hr->is_young()) {
5537     _cg1r->hot_card_cache()->reset_card_counts(hr);
5538   }
5539   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5540   free_list->add_ordered(hr);
5541 }
5542 
5543 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5544                                      FreeRegionList* free_list,
5545                                      bool par) {
5546   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5547   assert(free_list != NULL, "pre-condition");
5548 
5549   size_t hr_capacity = hr->capacity();
5550   // We need to read this before we make the region non-humongous,
5551   // otherwise the information will be gone.
5552   uint last_index = hr->last_hc_index();
5553   hr->clear_humongous();
5554   free_region(hr, free_list, par);
5555 
5556   uint i = hr->hrm_index() + 1;
5557   while (i < last_index) {
5558     HeapRegion* curr_hr = region_at(i);
5559     assert(curr_hr->is_continues_humongous(), "invariant");
5560     curr_hr->clear_humongous();
5561     free_region(curr_hr, free_list, par);
5562     i += 1;
5563   }
5564 }
5565 
5566 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5567                                        const HeapRegionSetCount& humongous_regions_removed) {
5568   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5569     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5570     _old_set.bulk_remove(old_regions_removed);
5571     _humongous_set.bulk_remove(humongous_regions_removed);
5572   }
5573 
5574 }
5575 
5576 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5577   assert(list != NULL, "list can't be null");
5578   if (!list->is_empty()) {
5579     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5580     _hrm.insert_list_into_free_list(list);
5581   }
5582 }
5583 
5584 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5585   _allocator->decrease_used(bytes);
5586 }
5587 
5588 class G1ParCleanupCTTask : public AbstractGangTask {
5589   G1SATBCardTableModRefBS* _ct_bs;
5590   G1CollectedHeap* _g1h;
5591   HeapRegion* volatile _su_head;
5592 public:
5593   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5594                      G1CollectedHeap* g1h) :
5595     AbstractGangTask("G1 Par Cleanup CT Task"),
5596     _ct_bs(ct_bs), _g1h(g1h) { }
5597 
5598   void work(uint worker_id) {
5599     HeapRegion* r;
5600     while (r = _g1h->pop_dirty_cards_region()) {
5601       clear_cards(r);
5602     }
5603   }
5604 
5605   void clear_cards(HeapRegion* r) {
5606     // Cards of the survivors should have already been dirtied.
5607     if (!r->is_survivor()) {
5608       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5609     }
5610   }
5611 };
5612 
5613 #ifndef PRODUCT
5614 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5615   G1CollectedHeap* _g1h;
5616   G1SATBCardTableModRefBS* _ct_bs;
5617 public:
5618   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5619     : _g1h(g1h), _ct_bs(ct_bs) { }
5620   virtual bool doHeapRegion(HeapRegion* r) {
5621     if (r->is_survivor()) {
5622       _g1h->verify_dirty_region(r);
5623     } else {
5624       _g1h->verify_not_dirty_region(r);
5625     }
5626     return false;
5627   }
5628 };
5629 
5630 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5631   // All of the region should be clean.
5632   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5633   MemRegion mr(hr->bottom(), hr->end());
5634   ct_bs->verify_not_dirty_region(mr);
5635 }
5636 
5637 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5638   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5639   // dirty allocated blocks as they allocate them. The thread that
5640   // retires each region and replaces it with a new one will do a
5641   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5642   // not dirty that area (one less thing to have to do while holding
5643   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5644   // is dirty.
5645   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5646   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5647   if (hr->is_young()) {
5648     ct_bs->verify_g1_young_region(mr);
5649   } else {
5650     ct_bs->verify_dirty_region(mr);
5651   }
5652 }
5653 
5654 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5655   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5656   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5657     verify_dirty_region(hr);
5658   }
5659 }
5660 
5661 void G1CollectedHeap::verify_dirty_young_regions() {
5662   verify_dirty_young_list(_young_list->first_region());
5663 }
5664 
5665 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5666                                                HeapWord* tams, HeapWord* end) {
5667   guarantee(tams <= end,
5668             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5669   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5670   if (result < end) {
5671     gclog_or_tty->cr();
5672     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5673                            bitmap_name, result);
5674     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5675                            bitmap_name, tams, end);
5676     return false;
5677   }
5678   return true;
5679 }
5680 
5681 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5682   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5683   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5684 
5685   HeapWord* bottom = hr->bottom();
5686   HeapWord* ptams  = hr->prev_top_at_mark_start();
5687   HeapWord* ntams  = hr->next_top_at_mark_start();
5688   HeapWord* end    = hr->end();
5689 
5690   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5691 
5692   bool res_n = true;
5693   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5694   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5695   // if we happen to be in that state.
5696   if (mark_in_progress() || !_cmThread->in_progress()) {
5697     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5698   }
5699   if (!res_p || !res_n) {
5700     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5701                            HR_FORMAT_PARAMS(hr));
5702     gclog_or_tty->print_cr("#### Caller: %s", caller);
5703     return false;
5704   }
5705   return true;
5706 }
5707 
5708 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5709   if (!G1VerifyBitmaps) return;
5710 
5711   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5712 }
5713 
5714 class G1VerifyBitmapClosure : public HeapRegionClosure {
5715 private:
5716   const char* _caller;
5717   G1CollectedHeap* _g1h;
5718   bool _failures;
5719 
5720 public:
5721   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5722     _caller(caller), _g1h(g1h), _failures(false) { }
5723 
5724   bool failures() { return _failures; }
5725 
5726   virtual bool doHeapRegion(HeapRegion* hr) {
5727     if (hr->is_continues_humongous()) return false;
5728 
5729     bool result = _g1h->verify_bitmaps(_caller, hr);
5730     if (!result) {
5731       _failures = true;
5732     }
5733     return false;
5734   }
5735 };
5736 
5737 void G1CollectedHeap::check_bitmaps(const char* caller) {
5738   if (!G1VerifyBitmaps) return;
5739 
5740   G1VerifyBitmapClosure cl(caller, this);
5741   heap_region_iterate(&cl);
5742   guarantee(!cl.failures(), "bitmap verification");
5743 }
5744 
5745 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5746  private:
5747   bool _failures;
5748  public:
5749   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5750 
5751   virtual bool doHeapRegion(HeapRegion* hr) {
5752     uint i = hr->hrm_index();
5753     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5754     if (hr->is_humongous()) {
5755       if (hr->in_collection_set()) {
5756         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5757         _failures = true;
5758         return true;
5759       }
5760       if (cset_state.is_in_cset()) {
5761         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5762         _failures = true;
5763         return true;
5764       }
5765       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5766         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5767         _failures = true;
5768         return true;
5769       }
5770     } else {
5771       if (cset_state.is_humongous()) {
5772         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5773         _failures = true;
5774         return true;
5775       }
5776       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5777         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5778                                hr->in_collection_set(), cset_state.value(), i);
5779         _failures = true;
5780         return true;
5781       }
5782       if (cset_state.is_in_cset()) {
5783         if (hr->is_young() != (cset_state.is_young())) {
5784           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5785                                  hr->is_young(), cset_state.value(), i);
5786           _failures = true;
5787           return true;
5788         }
5789         if (hr->is_old() != (cset_state.is_old())) {
5790           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5791                                  hr->is_old(), cset_state.value(), i);
5792           _failures = true;
5793           return true;
5794         }
5795       }
5796     }
5797     return false;
5798   }
5799 
5800   bool failures() const { return _failures; }
5801 };
5802 
5803 bool G1CollectedHeap::check_cset_fast_test() {
5804   G1CheckCSetFastTableClosure cl;
5805   _hrm.iterate(&cl);
5806   return !cl.failures();
5807 }
5808 #endif // PRODUCT
5809 
5810 void G1CollectedHeap::cleanUpCardTable() {
5811   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5812   double start = os::elapsedTime();
5813 
5814   {
5815     // Iterate over the dirty cards region list.
5816     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5817 
5818     set_par_threads();
5819     workers()->run_task(&cleanup_task);
5820     set_par_threads(0);
5821 #ifndef PRODUCT
5822     if (G1VerifyCTCleanup || VerifyAfterGC) {
5823       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5824       heap_region_iterate(&cleanup_verifier);
5825     }
5826 #endif
5827   }
5828 
5829   double elapsed = os::elapsedTime() - start;
5830   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5831 }
5832 
5833 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5834   size_t pre_used = 0;
5835   FreeRegionList local_free_list("Local List for CSet Freeing");
5836 
5837   double young_time_ms     = 0.0;
5838   double non_young_time_ms = 0.0;
5839 
5840   // Since the collection set is a superset of the the young list,
5841   // all we need to do to clear the young list is clear its
5842   // head and length, and unlink any young regions in the code below
5843   _young_list->clear();
5844 
5845   G1CollectorPolicy* policy = g1_policy();
5846 
5847   double start_sec = os::elapsedTime();
5848   bool non_young = true;
5849 
5850   HeapRegion* cur = cs_head;
5851   int age_bound = -1;
5852   size_t rs_lengths = 0;
5853 
5854   while (cur != NULL) {
5855     assert(!is_on_master_free_list(cur), "sanity");
5856     if (non_young) {
5857       if (cur->is_young()) {
5858         double end_sec = os::elapsedTime();
5859         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5860         non_young_time_ms += elapsed_ms;
5861 
5862         start_sec = os::elapsedTime();
5863         non_young = false;
5864       }
5865     } else {
5866       if (!cur->is_young()) {
5867         double end_sec = os::elapsedTime();
5868         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5869         young_time_ms += elapsed_ms;
5870 
5871         start_sec = os::elapsedTime();
5872         non_young = true;
5873       }
5874     }
5875 
5876     rs_lengths += cur->rem_set()->occupied_locked();
5877 
5878     HeapRegion* next = cur->next_in_collection_set();
5879     assert(cur->in_collection_set(), "bad CS");
5880     cur->set_next_in_collection_set(NULL);
5881     clear_in_cset(cur);
5882 
5883     if (cur->is_young()) {
5884       int index = cur->young_index_in_cset();
5885       assert(index != -1, "invariant");
5886       assert((uint) index < policy->young_cset_region_length(), "invariant");
5887       size_t words_survived = _surviving_young_words[index];
5888       cur->record_surv_words_in_group(words_survived);
5889 
5890       // At this point the we have 'popped' cur from the collection set
5891       // (linked via next_in_collection_set()) but it is still in the
5892       // young list (linked via next_young_region()). Clear the
5893       // _next_young_region field.
5894       cur->set_next_young_region(NULL);
5895     } else {
5896       int index = cur->young_index_in_cset();
5897       assert(index == -1, "invariant");
5898     }
5899 
5900     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5901             (!cur->is_young() && cur->young_index_in_cset() == -1),
5902             "invariant" );
5903 
5904     if (!cur->evacuation_failed()) {
5905       MemRegion used_mr = cur->used_region();
5906 
5907       // And the region is empty.
5908       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5909       pre_used += cur->used();
5910       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5911     } else {
5912       cur->uninstall_surv_rate_group();
5913       if (cur->is_young()) {
5914         cur->set_young_index_in_cset(-1);
5915       }
5916       cur->set_evacuation_failed(false);
5917       // The region is now considered to be old.
5918       cur->set_old();
5919       _old_set.add(cur);
5920       evacuation_info.increment_collectionset_used_after(cur->used());
5921     }
5922     cur = next;
5923   }
5924 
5925   evacuation_info.set_regions_freed(local_free_list.length());
5926   policy->record_max_rs_lengths(rs_lengths);
5927   policy->cset_regions_freed();
5928 
5929   double end_sec = os::elapsedTime();
5930   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5931 
5932   if (non_young) {
5933     non_young_time_ms += elapsed_ms;
5934   } else {
5935     young_time_ms += elapsed_ms;
5936   }
5937 
5938   prepend_to_freelist(&local_free_list);
5939   decrement_summary_bytes(pre_used);
5940   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5941   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5942 }
5943 
5944 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5945  private:
5946   FreeRegionList* _free_region_list;
5947   HeapRegionSet* _proxy_set;
5948   HeapRegionSetCount _humongous_regions_removed;
5949   size_t _freed_bytes;
5950  public:
5951 
5952   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5953     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5954   }
5955 
5956   virtual bool doHeapRegion(HeapRegion* r) {
5957     if (!r->is_starts_humongous()) {
5958       return false;
5959     }
5960 
5961     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5962 
5963     oop obj = (oop)r->bottom();
5964     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5965 
5966     // The following checks whether the humongous object is live are sufficient.
5967     // The main additional check (in addition to having a reference from the roots
5968     // or the young gen) is whether the humongous object has a remembered set entry.
5969     //
5970     // A humongous object cannot be live if there is no remembered set for it
5971     // because:
5972     // - there can be no references from within humongous starts regions referencing
5973     // the object because we never allocate other objects into them.
5974     // (I.e. there are no intra-region references that may be missed by the
5975     // remembered set)
5976     // - as soon there is a remembered set entry to the humongous starts region
5977     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5978     // until the end of a concurrent mark.
5979     //
5980     // It is not required to check whether the object has been found dead by marking
5981     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5982     // all objects allocated during that time are considered live.
5983     // SATB marking is even more conservative than the remembered set.
5984     // So if at this point in the collection there is no remembered set entry,
5985     // nobody has a reference to it.
5986     // At the start of collection we flush all refinement logs, and remembered sets
5987     // are completely up-to-date wrt to references to the humongous object.
5988     //
5989     // Other implementation considerations:
5990     // - never consider object arrays at this time because they would pose
5991     // considerable effort for cleaning up the the remembered sets. This is
5992     // required because stale remembered sets might reference locations that
5993     // are currently allocated into.
5994     uint region_idx = r->hrm_index();
5995     if (g1h->humongous_is_live(region_idx) ||
5996         g1h->humongous_region_is_always_live(region_idx)) {
5997 
5998       if (G1TraceEagerReclaimHumongousObjects) {
5999         gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6000                                region_idx,
6001                                obj->size()*HeapWordSize,
6002                                r->bottom(),
6003                                r->region_num(),
6004                                r->rem_set()->occupied(),
6005                                r->rem_set()->strong_code_roots_list_length(),
6006                                next_bitmap->isMarked(r->bottom()),
6007                                g1h->humongous_is_live(region_idx),
6008                                obj->is_objArray()
6009                               );
6010       }
6011 
6012       return false;
6013     }
6014 
6015     guarantee(!obj->is_objArray(),
6016               err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6017                       r->bottom()));
6018 
6019     if (G1TraceEagerReclaimHumongousObjects) {
6020       gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6021                              region_idx,
6022                              obj->size()*HeapWordSize,
6023                              r->bottom(),
6024                              r->region_num(),
6025                              r->rem_set()->occupied(),
6026                              r->rem_set()->strong_code_roots_list_length(),
6027                              next_bitmap->isMarked(r->bottom()),
6028                              g1h->humongous_is_live(region_idx),
6029                              obj->is_objArray()
6030                             );
6031     }
6032     // Need to clear mark bit of the humongous object if already set.
6033     if (next_bitmap->isMarked(r->bottom())) {
6034       next_bitmap->clear(r->bottom());
6035     }
6036     _freed_bytes += r->used();
6037     r->set_containing_set(NULL);
6038     _humongous_regions_removed.increment(1u, r->capacity());
6039     g1h->free_humongous_region(r, _free_region_list, false);
6040 
6041     return false;
6042   }
6043 
6044   HeapRegionSetCount& humongous_free_count() {
6045     return _humongous_regions_removed;
6046   }
6047 
6048   size_t bytes_freed() const {
6049     return _freed_bytes;
6050   }
6051 
6052   size_t humongous_reclaimed() const {
6053     return _humongous_regions_removed.length();
6054   }
6055 };
6056 
6057 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6058   assert_at_safepoint(true);
6059 
6060   if (!G1EagerReclaimHumongousObjects ||
6061       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6062     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6063     return;
6064   }
6065 
6066   double start_time = os::elapsedTime();
6067 
6068   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6069 
6070   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6071   heap_region_iterate(&cl);
6072 
6073   HeapRegionSetCount empty_set;
6074   remove_from_old_sets(empty_set, cl.humongous_free_count());
6075 
6076   G1HRPrinter* hr_printer = _g1h->hr_printer();
6077   if (hr_printer->is_active()) {
6078     FreeRegionListIterator iter(&local_cleanup_list);
6079     while (iter.more_available()) {
6080       HeapRegion* hr = iter.get_next();
6081       hr_printer->cleanup(hr);
6082     }
6083   }
6084 
6085   prepend_to_freelist(&local_cleanup_list);
6086   decrement_summary_bytes(cl.bytes_freed());
6087 
6088   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6089                                                                     cl.humongous_reclaimed());
6090 }
6091 
6092 // This routine is similar to the above but does not record
6093 // any policy statistics or update free lists; we are abandoning
6094 // the current incremental collection set in preparation of a
6095 // full collection. After the full GC we will start to build up
6096 // the incremental collection set again.
6097 // This is only called when we're doing a full collection
6098 // and is immediately followed by the tearing down of the young list.
6099 
6100 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6101   HeapRegion* cur = cs_head;
6102 
6103   while (cur != NULL) {
6104     HeapRegion* next = cur->next_in_collection_set();
6105     assert(cur->in_collection_set(), "bad CS");
6106     cur->set_next_in_collection_set(NULL);
6107     clear_in_cset(cur);
6108     cur->set_young_index_in_cset(-1);
6109     cur = next;
6110   }
6111 }
6112 
6113 void G1CollectedHeap::set_free_regions_coming() {
6114   if (G1ConcRegionFreeingVerbose) {
6115     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6116                            "setting free regions coming");
6117   }
6118 
6119   assert(!free_regions_coming(), "pre-condition");
6120   _free_regions_coming = true;
6121 }
6122 
6123 void G1CollectedHeap::reset_free_regions_coming() {
6124   assert(free_regions_coming(), "pre-condition");
6125 
6126   {
6127     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6128     _free_regions_coming = false;
6129     SecondaryFreeList_lock->notify_all();
6130   }
6131 
6132   if (G1ConcRegionFreeingVerbose) {
6133     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6134                            "reset free regions coming");
6135   }
6136 }
6137 
6138 void G1CollectedHeap::wait_while_free_regions_coming() {
6139   // Most of the time we won't have to wait, so let's do a quick test
6140   // first before we take the lock.
6141   if (!free_regions_coming()) {
6142     return;
6143   }
6144 
6145   if (G1ConcRegionFreeingVerbose) {
6146     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6147                            "waiting for free regions");
6148   }
6149 
6150   {
6151     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6152     while (free_regions_coming()) {
6153       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6154     }
6155   }
6156 
6157   if (G1ConcRegionFreeingVerbose) {
6158     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6159                            "done waiting for free regions");
6160   }
6161 }
6162 
6163 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6164   assert(heap_lock_held_for_gc(),
6165               "the heap lock should already be held by or for this thread");
6166   _young_list->push_region(hr);
6167 }
6168 
6169 class NoYoungRegionsClosure: public HeapRegionClosure {
6170 private:
6171   bool _success;
6172 public:
6173   NoYoungRegionsClosure() : _success(true) { }
6174   bool doHeapRegion(HeapRegion* r) {
6175     if (r->is_young()) {
6176       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6177                              r->bottom(), r->end());
6178       _success = false;
6179     }
6180     return false;
6181   }
6182   bool success() { return _success; }
6183 };
6184 
6185 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6186   bool ret = _young_list->check_list_empty(check_sample);
6187 
6188   if (check_heap) {
6189     NoYoungRegionsClosure closure;
6190     heap_region_iterate(&closure);
6191     ret = ret && closure.success();
6192   }
6193 
6194   return ret;
6195 }
6196 
6197 class TearDownRegionSetsClosure : public HeapRegionClosure {
6198 private:
6199   HeapRegionSet *_old_set;
6200 
6201 public:
6202   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6203 
6204   bool doHeapRegion(HeapRegion* r) {
6205     if (r->is_old()) {
6206       _old_set->remove(r);
6207     } else {
6208       // We ignore free regions, we'll empty the free list afterwards.
6209       // We ignore young regions, we'll empty the young list afterwards.
6210       // We ignore humongous regions, we're not tearing down the
6211       // humongous regions set.
6212       assert(r->is_free() || r->is_young() || r->is_humongous(),
6213              "it cannot be another type");
6214     }
6215     return false;
6216   }
6217 
6218   ~TearDownRegionSetsClosure() {
6219     assert(_old_set->is_empty(), "post-condition");
6220   }
6221 };
6222 
6223 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6224   assert_at_safepoint(true /* should_be_vm_thread */);
6225 
6226   if (!free_list_only) {
6227     TearDownRegionSetsClosure cl(&_old_set);
6228     heap_region_iterate(&cl);
6229 
6230     // Note that emptying the _young_list is postponed and instead done as
6231     // the first step when rebuilding the regions sets again. The reason for
6232     // this is that during a full GC string deduplication needs to know if
6233     // a collected region was young or old when the full GC was initiated.
6234   }
6235   _hrm.remove_all_free_regions();
6236 }
6237 
6238 class RebuildRegionSetsClosure : public HeapRegionClosure {
6239 private:
6240   bool            _free_list_only;
6241   HeapRegionSet*   _old_set;
6242   HeapRegionManager*   _hrm;
6243   size_t          _total_used;
6244 
6245 public:
6246   RebuildRegionSetsClosure(bool free_list_only,
6247                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6248     _free_list_only(free_list_only),
6249     _old_set(old_set), _hrm(hrm), _total_used(0) {
6250     assert(_hrm->num_free_regions() == 0, "pre-condition");
6251     if (!free_list_only) {
6252       assert(_old_set->is_empty(), "pre-condition");
6253     }
6254   }
6255 
6256   bool doHeapRegion(HeapRegion* r) {
6257     if (r->is_continues_humongous()) {
6258       return false;
6259     }
6260 
6261     if (r->is_empty()) {
6262       // Add free regions to the free list
6263       r->set_free();
6264       r->set_allocation_context(AllocationContext::system());
6265       _hrm->insert_into_free_list(r);
6266     } else if (!_free_list_only) {
6267       assert(!r->is_young(), "we should not come across young regions");
6268 
6269       if (r->is_humongous()) {
6270         // We ignore humongous regions, we left the humongous set unchanged
6271       } else {
6272         // Objects that were compacted would have ended up on regions
6273         // that were previously old or free.
6274         assert(r->is_free() || r->is_old(), "invariant");
6275         // We now consider them old, so register as such.
6276         r->set_old();
6277         _old_set->add(r);
6278       }
6279       _total_used += r->used();
6280     }
6281 
6282     return false;
6283   }
6284 
6285   size_t total_used() {
6286     return _total_used;
6287   }
6288 };
6289 
6290 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6291   assert_at_safepoint(true /* should_be_vm_thread */);
6292 
6293   if (!free_list_only) {
6294     _young_list->empty_list();
6295   }
6296 
6297   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6298   heap_region_iterate(&cl);
6299 
6300   if (!free_list_only) {
6301     _allocator->set_used(cl.total_used());
6302   }
6303   assert(_allocator->used_unlocked() == recalculate_used(),
6304          err_msg("inconsistent _allocator->used_unlocked(), "
6305                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6306                  _allocator->used_unlocked(), recalculate_used()));
6307 }
6308 
6309 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6310   _refine_cte_cl->set_concurrent(concurrent);
6311 }
6312 
6313 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6314   HeapRegion* hr = heap_region_containing(p);
6315   return hr->is_in(p);
6316 }
6317 
6318 // Methods for the mutator alloc region
6319 
6320 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6321                                                       bool force) {
6322   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6323   assert(!force || g1_policy()->can_expand_young_list(),
6324          "if force is true we should be able to expand the young list");
6325   bool young_list_full = g1_policy()->is_young_list_full();
6326   if (force || !young_list_full) {
6327     HeapRegion* new_alloc_region = new_region(word_size,
6328                                               false /* is_old */,
6329                                               false /* do_expand */);
6330     if (new_alloc_region != NULL) {
6331       set_region_short_lived_locked(new_alloc_region);
6332       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6333       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6334       return new_alloc_region;
6335     }
6336   }
6337   return NULL;
6338 }
6339 
6340 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6341                                                   size_t allocated_bytes) {
6342   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6343   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6344 
6345   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6346   _allocator->increase_used(allocated_bytes);
6347   _hr_printer.retire(alloc_region);
6348   // We update the eden sizes here, when the region is retired,
6349   // instead of when it's allocated, since this is the point that its
6350   // used space has been recored in _summary_bytes_used.
6351   g1mm()->update_eden_size();
6352 }
6353 
6354 void G1CollectedHeap::set_par_threads() {
6355   // Don't change the number of workers.  Use the value previously set
6356   // in the workgroup.
6357   uint n_workers = workers()->active_workers();
6358   assert(UseDynamicNumberOfGCThreads ||
6359            n_workers == workers()->total_workers(),
6360       "Otherwise should be using the total number of workers");
6361   if (n_workers == 0) {
6362     assert(false, "Should have been set in prior evacuation pause.");
6363     n_workers = ParallelGCThreads;
6364     workers()->set_active_workers(n_workers);
6365   }
6366   set_par_threads(n_workers);
6367 }
6368 
6369 // Methods for the GC alloc regions
6370 
6371 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6372                                                  uint count,
6373                                                  InCSetState dest) {
6374   assert(FreeList_lock->owned_by_self(), "pre-condition");
6375 
6376   if (count < g1_policy()->max_regions(dest)) {
6377     const bool is_survivor = (dest.is_young());
6378     HeapRegion* new_alloc_region = new_region(word_size,
6379                                               !is_survivor,
6380                                               true /* do_expand */);
6381     if (new_alloc_region != NULL) {
6382       // We really only need to do this for old regions given that we
6383       // should never scan survivors. But it doesn't hurt to do it
6384       // for survivors too.
6385       new_alloc_region->record_timestamp();
6386       if (is_survivor) {
6387         new_alloc_region->set_survivor();
6388         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6389         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6390       } else {
6391         new_alloc_region->set_old();
6392         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6393         check_bitmaps("Old Region Allocation", new_alloc_region);
6394       }
6395       bool during_im = g1_policy()->during_initial_mark_pause();
6396       new_alloc_region->note_start_of_copying(during_im);
6397       return new_alloc_region;
6398     }
6399   }
6400   return NULL;
6401 }
6402 
6403 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6404                                              size_t allocated_bytes,
6405                                              InCSetState dest) {
6406   bool during_im = g1_policy()->during_initial_mark_pause();
6407   alloc_region->note_end_of_copying(during_im);
6408   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6409   if (dest.is_young()) {
6410     young_list()->add_survivor_region(alloc_region);
6411   } else {
6412     _old_set.add(alloc_region);
6413   }
6414   _hr_printer.retire(alloc_region);
6415 }
6416 
6417 // Heap region set verification
6418 
6419 class VerifyRegionListsClosure : public HeapRegionClosure {
6420 private:
6421   HeapRegionSet*   _old_set;
6422   HeapRegionSet*   _humongous_set;
6423   HeapRegionManager*   _hrm;
6424 
6425 public:
6426   HeapRegionSetCount _old_count;
6427   HeapRegionSetCount _humongous_count;
6428   HeapRegionSetCount _free_count;
6429 
6430   VerifyRegionListsClosure(HeapRegionSet* old_set,
6431                            HeapRegionSet* humongous_set,
6432                            HeapRegionManager* hrm) :
6433     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6434     _old_count(), _humongous_count(), _free_count(){ }
6435 
6436   bool doHeapRegion(HeapRegion* hr) {
6437     if (hr->is_continues_humongous()) {
6438       return false;
6439     }
6440 
6441     if (hr->is_young()) {
6442       // TODO
6443     } else if (hr->is_starts_humongous()) {
6444       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6445       _humongous_count.increment(1u, hr->capacity());
6446     } else if (hr->is_empty()) {
6447       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6448       _free_count.increment(1u, hr->capacity());
6449     } else if (hr->is_old()) {
6450       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6451       _old_count.increment(1u, hr->capacity());
6452     } else {
6453       ShouldNotReachHere();
6454     }
6455     return false;
6456   }
6457 
6458   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6459     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6460     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6461         old_set->total_capacity_bytes(), _old_count.capacity()));
6462 
6463     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6464     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6465         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6466 
6467     guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
6468     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6469         free_list->total_capacity_bytes(), _free_count.capacity()));
6470   }
6471 };
6472 
6473 void G1CollectedHeap::verify_region_sets() {
6474   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6475 
6476   // First, check the explicit lists.
6477   _hrm.verify();
6478   {
6479     // Given that a concurrent operation might be adding regions to
6480     // the secondary free list we have to take the lock before
6481     // verifying it.
6482     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6483     _secondary_free_list.verify_list();
6484   }
6485 
6486   // If a concurrent region freeing operation is in progress it will
6487   // be difficult to correctly attributed any free regions we come
6488   // across to the correct free list given that they might belong to
6489   // one of several (free_list, secondary_free_list, any local lists,
6490   // etc.). So, if that's the case we will skip the rest of the
6491   // verification operation. Alternatively, waiting for the concurrent
6492   // operation to complete will have a non-trivial effect on the GC's
6493   // operation (no concurrent operation will last longer than the
6494   // interval between two calls to verification) and it might hide
6495   // any issues that we would like to catch during testing.
6496   if (free_regions_coming()) {
6497     return;
6498   }
6499 
6500   // Make sure we append the secondary_free_list on the free_list so
6501   // that all free regions we will come across can be safely
6502   // attributed to the free_list.
6503   append_secondary_free_list_if_not_empty_with_lock();
6504 
6505   // Finally, make sure that the region accounting in the lists is
6506   // consistent with what we see in the heap.
6507 
6508   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6509   heap_region_iterate(&cl);
6510   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6511 }
6512 
6513 // Optimized nmethod scanning
6514 
6515 class RegisterNMethodOopClosure: public OopClosure {
6516   G1CollectedHeap* _g1h;
6517   nmethod* _nm;
6518 
6519   template <class T> void do_oop_work(T* p) {
6520     T heap_oop = oopDesc::load_heap_oop(p);
6521     if (!oopDesc::is_null(heap_oop)) {
6522       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6523       HeapRegion* hr = _g1h->heap_region_containing(obj);
6524       assert(!hr->is_continues_humongous(),
6525              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6526                      " starting at "HR_FORMAT,
6527                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6528 
6529       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6530       hr->add_strong_code_root_locked(_nm);
6531     }
6532   }
6533 
6534 public:
6535   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6536     _g1h(g1h), _nm(nm) {}
6537 
6538   void do_oop(oop* p)       { do_oop_work(p); }
6539   void do_oop(narrowOop* p) { do_oop_work(p); }
6540 };
6541 
6542 class UnregisterNMethodOopClosure: public OopClosure {
6543   G1CollectedHeap* _g1h;
6544   nmethod* _nm;
6545 
6546   template <class T> void do_oop_work(T* p) {
6547     T heap_oop = oopDesc::load_heap_oop(p);
6548     if (!oopDesc::is_null(heap_oop)) {
6549       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6550       HeapRegion* hr = _g1h->heap_region_containing(obj);
6551       assert(!hr->is_continues_humongous(),
6552              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6553                      " starting at "HR_FORMAT,
6554                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6555 
6556       hr->remove_strong_code_root(_nm);
6557     }
6558   }
6559 
6560 public:
6561   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6562     _g1h(g1h), _nm(nm) {}
6563 
6564   void do_oop(oop* p)       { do_oop_work(p); }
6565   void do_oop(narrowOop* p) { do_oop_work(p); }
6566 };
6567 
6568 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6569   CollectedHeap::register_nmethod(nm);
6570 
6571   guarantee(nm != NULL, "sanity");
6572   RegisterNMethodOopClosure reg_cl(this, nm);
6573   nm->oops_do(&reg_cl);
6574 }
6575 
6576 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6577   CollectedHeap::unregister_nmethod(nm);
6578 
6579   guarantee(nm != NULL, "sanity");
6580   UnregisterNMethodOopClosure reg_cl(this, nm);
6581   nm->oops_do(&reg_cl, true);
6582 }
6583 
6584 void G1CollectedHeap::purge_code_root_memory() {
6585   double purge_start = os::elapsedTime();
6586   G1CodeRootSet::purge();
6587   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6588   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6589 }
6590 
6591 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6592   G1CollectedHeap* _g1h;
6593 
6594 public:
6595   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6596     _g1h(g1h) {}
6597 
6598   void do_code_blob(CodeBlob* cb) {
6599     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6600     if (nm == NULL) {
6601       return;
6602     }
6603 
6604     if (ScavengeRootsInCode) {
6605       _g1h->register_nmethod(nm);
6606     }
6607   }
6608 };
6609 
6610 void G1CollectedHeap::rebuild_strong_code_roots() {
6611   RebuildStrongCodeRootClosure blob_cl(this);
6612   CodeCache::blobs_do(&blob_cl);
6613 }