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   CollectedHeap(),
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   _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1774                           /* are_GC_task_threads */true,
1775                           /* are_ConcurrentGC_threads */false);
1776   _workers->initialize_workers();
1777 
1778   _allocator = G1Allocator::create_allocator(_g1h);
1779   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1780 
1781   int n_queues = MAX2((int)ParallelGCThreads, 1);
1782   _task_queues = new RefToScanQueueSet(n_queues);
1783 
1784   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1785   assert(n_rem_sets > 0, "Invariant.");
1786 
1787   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1788   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1789   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1790 
1791   for (int i = 0; i < n_queues; i++) {
1792     RefToScanQueue* q = new RefToScanQueue();
1793     q->initialize();
1794     _task_queues->register_queue(i, q);
1795     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1796   }
1797   clear_cset_start_regions();
1798 
1799   // Initialize the G1EvacuationFailureALot counters and flags.
1800   NOT_PRODUCT(reset_evacuation_should_fail();)
1801 
1802   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1803 }
1804 
1805 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1806                                                                  size_t size,
1807                                                                  size_t translation_factor) {
1808   // Allocate a new reserved space, preferring to use large pages.
1809   ReservedSpace rs(size, true);
1810   G1RegionToSpaceMapper* result  =
1811     G1RegionToSpaceMapper::create_mapper(rs,
1812                                          size,
1813                                          rs.alignment(),
1814                                          HeapRegion::GrainBytes,
1815                                          translation_factor,
1816                                          mtGC);
1817   if (TracePageSizes) {
1818     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1819                            description, rs.alignment(), p2i(rs.base()), rs.size(), rs.alignment(), size);
1820   }
1821   return result;
1822 }
1823 
1824 jint G1CollectedHeap::initialize() {
1825   CollectedHeap::pre_initialize();
1826   os::enable_vtime();
1827 
1828   G1Log::init();
1829 
1830   // Necessary to satisfy locking discipline assertions.
1831 
1832   MutexLocker x(Heap_lock);
1833 
1834   // We have to initialize the printer before committing the heap, as
1835   // it will be used then.
1836   _hr_printer.set_active(G1PrintHeapRegions);
1837 
1838   // While there are no constraints in the GC code that HeapWordSize
1839   // be any particular value, there are multiple other areas in the
1840   // system which believe this to be true (e.g. oop->object_size in some
1841   // cases incorrectly returns the size in wordSize units rather than
1842   // HeapWordSize).
1843   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1844 
1845   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1846   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1847   size_t heap_alignment = collector_policy()->heap_alignment();
1848 
1849   // Ensure that the sizes are properly aligned.
1850   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1851   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1852   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1853 
1854   _refine_cte_cl = new RefineCardTableEntryClosure();
1855 
1856   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1857 
1858   // Reserve the maximum.
1859 
1860   // When compressed oops are enabled, the preferred heap base
1861   // is calculated by subtracting the requested size from the
1862   // 32Gb boundary and using the result as the base address for
1863   // heap reservation. If the requested size is not aligned to
1864   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1865   // into the ReservedHeapSpace constructor) then the actual
1866   // base of the reserved heap may end up differing from the
1867   // address that was requested (i.e. the preferred heap base).
1868   // If this happens then we could end up using a non-optimal
1869   // compressed oops mode.
1870 
1871   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1872                                                  heap_alignment);
1873 
1874   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1875 
1876   // Create the barrier set for the entire reserved region.
1877   G1SATBCardTableLoggingModRefBS* bs
1878     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1879   bs->initialize();
1880   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1881   set_barrier_set(bs);
1882 
1883   // Also create a G1 rem set.
1884   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1885 
1886   // Carve out the G1 part of the heap.
1887 
1888   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1889   G1RegionToSpaceMapper* heap_storage =
1890     G1RegionToSpaceMapper::create_mapper(g1_rs,
1891                                          g1_rs.size(),
1892                                          UseLargePages ? os::large_page_size() : os::vm_page_size(),
1893                                          HeapRegion::GrainBytes,
1894                                          1,
1895                                          mtJavaHeap);
1896   heap_storage->set_mapping_changed_listener(&_listener);
1897 
1898   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1899   G1RegionToSpaceMapper* bot_storage =
1900     create_aux_memory_mapper("Block offset table",
1901                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1902                              G1BlockOffsetSharedArray::N_bytes);
1903 
1904   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1905   G1RegionToSpaceMapper* cardtable_storage =
1906     create_aux_memory_mapper("Card table",
1907                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1908                              G1BlockOffsetSharedArray::N_bytes);
1909 
1910   G1RegionToSpaceMapper* card_counts_storage =
1911     create_aux_memory_mapper("Card counts table",
1912                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1913                              G1BlockOffsetSharedArray::N_bytes);
1914 
1915   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1916   G1RegionToSpaceMapper* prev_bitmap_storage =
1917     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
1918   G1RegionToSpaceMapper* next_bitmap_storage =
1919     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
1920 
1921   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1922   g1_barrier_set()->initialize(cardtable_storage);
1923    // Do later initialization work for concurrent refinement.
1924   _cg1r->init(card_counts_storage);
1925 
1926   // 6843694 - ensure that the maximum region index can fit
1927   // in the remembered set structures.
1928   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1929   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1930 
1931   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1932   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1933   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1934             "too many cards per region");
1935 
1936   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1937 
1938   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1939 
1940   _g1h = this;
1941 
1942   _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1943   _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1944 
1945   // Create the ConcurrentMark data structure and thread.
1946   // (Must do this late, so that "max_regions" is defined.)
1947   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1948   if (_cm == NULL || !_cm->completed_initialization()) {
1949     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1950     return JNI_ENOMEM;
1951   }
1952   _cmThread = _cm->cmThread();
1953 
1954   // Initialize the from_card cache structure of HeapRegionRemSet.
1955   HeapRegionRemSet::init_heap(max_regions());
1956 
1957   // Now expand into the initial heap size.
1958   if (!expand(init_byte_size)) {
1959     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1960     return JNI_ENOMEM;
1961   }
1962 
1963   // Perform any initialization actions delegated to the policy.
1964   g1_policy()->init();
1965 
1966   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1967                                                SATB_Q_FL_lock,
1968                                                G1SATBProcessCompletedThreshold,
1969                                                Shared_SATB_Q_lock);
1970 
1971   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1972                                                 DirtyCardQ_CBL_mon,
1973                                                 DirtyCardQ_FL_lock,
1974                                                 concurrent_g1_refine()->yellow_zone(),
1975                                                 concurrent_g1_refine()->red_zone(),
1976                                                 Shared_DirtyCardQ_lock);
1977 
1978   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1979                                     DirtyCardQ_CBL_mon,
1980                                     DirtyCardQ_FL_lock,
1981                                     -1, // never trigger processing
1982                                     -1, // no limit on length
1983                                     Shared_DirtyCardQ_lock,
1984                                     &JavaThread::dirty_card_queue_set());
1985 
1986   // Initialize the card queue set used to hold cards containing
1987   // references into the collection set.
1988   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1989                                              DirtyCardQ_CBL_mon,
1990                                              DirtyCardQ_FL_lock,
1991                                              -1, // never trigger processing
1992                                              -1, // no limit on length
1993                                              Shared_DirtyCardQ_lock,
1994                                              &JavaThread::dirty_card_queue_set());
1995 
1996   // Here we allocate the dummy HeapRegion that is required by the
1997   // G1AllocRegion class.
1998   HeapRegion* dummy_region = _hrm.get_dummy_region();
1999 
2000   // We'll re-use the same region whether the alloc region will
2001   // require BOT updates or not and, if it doesn't, then a non-young
2002   // region will complain that it cannot support allocations without
2003   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2004   dummy_region->set_eden();
2005   // Make sure it's full.
2006   dummy_region->set_top(dummy_region->end());
2007   G1AllocRegion::setup(this, dummy_region);
2008 
2009   _allocator->init_mutator_alloc_region();
2010 
2011   // Do create of the monitoring and management support so that
2012   // values in the heap have been properly initialized.
2013   _g1mm = new G1MonitoringSupport(this);
2014 
2015   G1StringDedup::initialize();
2016 
2017   return JNI_OK;
2018 }
2019 
2020 void G1CollectedHeap::stop() {
2021   // Stop all concurrent threads. We do this to make sure these threads
2022   // do not continue to execute and access resources (e.g. gclog_or_tty)
2023   // that are destroyed during shutdown.
2024   _cg1r->stop();
2025   _cmThread->stop();
2026   if (G1StringDedup::is_enabled()) {
2027     G1StringDedup::stop();
2028   }
2029 }
2030 
2031 void G1CollectedHeap::clear_humongous_is_live_table() {
2032   guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2033   _humongous_is_live.clear();
2034 }
2035 
2036 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2037   return HeapRegion::max_region_size();
2038 }
2039 
2040 void G1CollectedHeap::post_initialize() {
2041   CollectedHeap::post_initialize();
2042   ref_processing_init();
2043 }
2044 
2045 void G1CollectedHeap::ref_processing_init() {
2046   // Reference processing in G1 currently works as follows:
2047   //
2048   // * There are two reference processor instances. One is
2049   //   used to record and process discovered references
2050   //   during concurrent marking; the other is used to
2051   //   record and process references during STW pauses
2052   //   (both full and incremental).
2053   // * Both ref processors need to 'span' the entire heap as
2054   //   the regions in the collection set may be dotted around.
2055   //
2056   // * For the concurrent marking ref processor:
2057   //   * Reference discovery is enabled at initial marking.
2058   //   * Reference discovery is disabled and the discovered
2059   //     references processed etc during remarking.
2060   //   * Reference discovery is MT (see below).
2061   //   * Reference discovery requires a barrier (see below).
2062   //   * Reference processing may or may not be MT
2063   //     (depending on the value of ParallelRefProcEnabled
2064   //     and ParallelGCThreads).
2065   //   * A full GC disables reference discovery by the CM
2066   //     ref processor and abandons any entries on it's
2067   //     discovered lists.
2068   //
2069   // * For the STW processor:
2070   //   * Non MT discovery is enabled at the start of a full GC.
2071   //   * Processing and enqueueing during a full GC is non-MT.
2072   //   * During a full GC, references are processed after marking.
2073   //
2074   //   * Discovery (may or may not be MT) is enabled at the start
2075   //     of an incremental evacuation pause.
2076   //   * References are processed near the end of a STW evacuation pause.
2077   //   * For both types of GC:
2078   //     * Discovery is atomic - i.e. not concurrent.
2079   //     * Reference discovery will not need a barrier.
2080 
2081   MemRegion mr = reserved_region();
2082 
2083   // Concurrent Mark ref processor
2084   _ref_processor_cm =
2085     new ReferenceProcessor(mr,    // span
2086                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2087                                 // mt processing
2088                            (int) ParallelGCThreads,
2089                                 // degree of mt processing
2090                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2091                                 // mt discovery
2092                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2093                                 // degree of mt discovery
2094                            false,
2095                                 // Reference discovery is not atomic
2096                            &_is_alive_closure_cm);
2097                                 // is alive closure
2098                                 // (for efficiency/performance)
2099 
2100   // STW ref processor
2101   _ref_processor_stw =
2102     new ReferenceProcessor(mr,    // span
2103                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2104                                 // mt processing
2105                            MAX2((int)ParallelGCThreads, 1),
2106                                 // degree of mt processing
2107                            (ParallelGCThreads > 1),
2108                                 // mt discovery
2109                            MAX2((int)ParallelGCThreads, 1),
2110                                 // degree of mt discovery
2111                            true,
2112                                 // Reference discovery is atomic
2113                            &_is_alive_closure_stw);
2114                                 // is alive closure
2115                                 // (for efficiency/performance)
2116 }
2117 
2118 size_t G1CollectedHeap::capacity() const {
2119   return _hrm.length() * HeapRegion::GrainBytes;
2120 }
2121 
2122 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2123   assert(!hr->is_continues_humongous(), "pre-condition");
2124   hr->reset_gc_time_stamp();
2125   if (hr->is_starts_humongous()) {
2126     uint first_index = hr->hrm_index() + 1;
2127     uint last_index = hr->last_hc_index();
2128     for (uint i = first_index; i < last_index; i += 1) {
2129       HeapRegion* chr = region_at(i);
2130       assert(chr->is_continues_humongous(), "sanity");
2131       chr->reset_gc_time_stamp();
2132     }
2133   }
2134 }
2135 
2136 #ifndef PRODUCT
2137 
2138 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2139 private:
2140   unsigned _gc_time_stamp;
2141   bool _failures;
2142 
2143 public:
2144   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2145     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2146 
2147   virtual bool doHeapRegion(HeapRegion* hr) {
2148     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2149     if (_gc_time_stamp != region_gc_time_stamp) {
2150       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2151                              "expected %d", HR_FORMAT_PARAMS(hr),
2152                              region_gc_time_stamp, _gc_time_stamp);
2153       _failures = true;
2154     }
2155     return false;
2156   }
2157 
2158   bool failures() { return _failures; }
2159 };
2160 
2161 void G1CollectedHeap::check_gc_time_stamps() {
2162   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2163   heap_region_iterate(&cl);
2164   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2165 }
2166 #endif // PRODUCT
2167 
2168 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2169                                                  DirtyCardQueue* into_cset_dcq,
2170                                                  bool concurrent,
2171                                                  uint worker_i) {
2172   // Clean cards in the hot card cache
2173   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2174   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2175 
2176   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2177   size_t n_completed_buffers = 0;
2178   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2179     n_completed_buffers++;
2180   }
2181   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2182   dcqs.clear_n_completed_buffers();
2183   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2184 }
2185 
2186 
2187 // Computes the sum of the storage used by the various regions.
2188 size_t G1CollectedHeap::used() const {
2189   return _allocator->used();
2190 }
2191 
2192 size_t G1CollectedHeap::used_unlocked() const {
2193   return _allocator->used_unlocked();
2194 }
2195 
2196 class SumUsedClosure: public HeapRegionClosure {
2197   size_t _used;
2198 public:
2199   SumUsedClosure() : _used(0) {}
2200   bool doHeapRegion(HeapRegion* r) {
2201     if (!r->is_continues_humongous()) {
2202       _used += r->used();
2203     }
2204     return false;
2205   }
2206   size_t result() { return _used; }
2207 };
2208 
2209 size_t G1CollectedHeap::recalculate_used() const {
2210   double recalculate_used_start = os::elapsedTime();
2211 
2212   SumUsedClosure blk;
2213   heap_region_iterate(&blk);
2214 
2215   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2216   return blk.result();
2217 }
2218 
2219 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2220   switch (cause) {
2221     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2222     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2223     case GCCause::_g1_humongous_allocation: return true;
2224     case GCCause::_update_allocation_context_stats_inc: return true;
2225     case GCCause::_wb_conc_mark:            return true;
2226     default:                                return false;
2227   }
2228 }
2229 
2230 #ifndef PRODUCT
2231 void G1CollectedHeap::allocate_dummy_regions() {
2232   // Let's fill up most of the region
2233   size_t word_size = HeapRegion::GrainWords - 1024;
2234   // And as a result the region we'll allocate will be humongous.
2235   guarantee(is_humongous(word_size), "sanity");
2236 
2237   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2238     // Let's use the existing mechanism for the allocation
2239     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2240                                                  AllocationContext::system());
2241     if (dummy_obj != NULL) {
2242       MemRegion mr(dummy_obj, word_size);
2243       CollectedHeap::fill_with_object(mr);
2244     } else {
2245       // If we can't allocate once, we probably cannot allocate
2246       // again. Let's get out of the loop.
2247       break;
2248     }
2249   }
2250 }
2251 #endif // !PRODUCT
2252 
2253 void G1CollectedHeap::increment_old_marking_cycles_started() {
2254   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2255     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2256     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2257     _old_marking_cycles_started, _old_marking_cycles_completed));
2258 
2259   _old_marking_cycles_started++;
2260 }
2261 
2262 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2263   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2264 
2265   // We assume that if concurrent == true, then the caller is a
2266   // concurrent thread that was joined the Suspendible Thread
2267   // Set. If there's ever a cheap way to check this, we should add an
2268   // assert here.
2269 
2270   // Given that this method is called at the end of a Full GC or of a
2271   // concurrent cycle, and those can be nested (i.e., a Full GC can
2272   // interrupt a concurrent cycle), the number of full collections
2273   // completed should be either one (in the case where there was no
2274   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2275   // behind the number of full collections started.
2276 
2277   // This is the case for the inner caller, i.e. a Full GC.
2278   assert(concurrent ||
2279          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2280          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2281          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2282                  "is inconsistent with _old_marking_cycles_completed = %u",
2283                  _old_marking_cycles_started, _old_marking_cycles_completed));
2284 
2285   // This is the case for the outer caller, i.e. the concurrent cycle.
2286   assert(!concurrent ||
2287          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2288          err_msg("for outer caller (concurrent cycle): "
2289                  "_old_marking_cycles_started = %u "
2290                  "is inconsistent with _old_marking_cycles_completed = %u",
2291                  _old_marking_cycles_started, _old_marking_cycles_completed));
2292 
2293   _old_marking_cycles_completed += 1;
2294 
2295   // We need to clear the "in_progress" flag in the CM thread before
2296   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2297   // is set) so that if a waiter requests another System.gc() it doesn't
2298   // incorrectly see that a marking cycle is still in progress.
2299   if (concurrent) {
2300     _cmThread->clear_in_progress();
2301   }
2302 
2303   // This notify_all() will ensure that a thread that called
2304   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2305   // and it's waiting for a full GC to finish will be woken up. It is
2306   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2307   FullGCCount_lock->notify_all();
2308 }
2309 
2310 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2311   _concurrent_cycle_started = true;
2312   _gc_timer_cm->register_gc_start(start_time);
2313 
2314   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2315   trace_heap_before_gc(_gc_tracer_cm);
2316 }
2317 
2318 void G1CollectedHeap::register_concurrent_cycle_end() {
2319   if (_concurrent_cycle_started) {
2320     if (_cm->has_aborted()) {
2321       _gc_tracer_cm->report_concurrent_mode_failure();
2322     }
2323 
2324     _gc_timer_cm->register_gc_end();
2325     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2326 
2327     // Clear state variables to prepare for the next concurrent cycle.
2328     _concurrent_cycle_started = false;
2329     _heap_summary_sent = false;
2330   }
2331 }
2332 
2333 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2334   if (_concurrent_cycle_started) {
2335     // This function can be called when:
2336     //  the cleanup pause is run
2337     //  the concurrent cycle is aborted before the cleanup pause.
2338     //  the concurrent cycle is aborted after the cleanup pause,
2339     //   but before the concurrent cycle end has been registered.
2340     // Make sure that we only send the heap information once.
2341     if (!_heap_summary_sent) {
2342       trace_heap_after_gc(_gc_tracer_cm);
2343       _heap_summary_sent = true;
2344     }
2345   }
2346 }
2347 
2348 G1YCType G1CollectedHeap::yc_type() {
2349   bool is_young = g1_policy()->gcs_are_young();
2350   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2351   bool is_during_mark = mark_in_progress();
2352 
2353   if (is_initial_mark) {
2354     return InitialMark;
2355   } else if (is_during_mark) {
2356     return DuringMark;
2357   } else if (is_young) {
2358     return Normal;
2359   } else {
2360     return Mixed;
2361   }
2362 }
2363 
2364 void G1CollectedHeap::collect(GCCause::Cause cause) {
2365   assert_heap_not_locked();
2366 
2367   uint gc_count_before;
2368   uint old_marking_count_before;
2369   uint full_gc_count_before;
2370   bool retry_gc;
2371 
2372   do {
2373     retry_gc = false;
2374 
2375     {
2376       MutexLocker ml(Heap_lock);
2377 
2378       // Read the GC count while holding the Heap_lock
2379       gc_count_before = total_collections();
2380       full_gc_count_before = total_full_collections();
2381       old_marking_count_before = _old_marking_cycles_started;
2382     }
2383 
2384     if (should_do_concurrent_full_gc(cause)) {
2385       // Schedule an initial-mark evacuation pause that will start a
2386       // concurrent cycle. We're setting word_size to 0 which means that
2387       // we are not requesting a post-GC allocation.
2388       VM_G1IncCollectionPause op(gc_count_before,
2389                                  0,     /* word_size */
2390                                  true,  /* should_initiate_conc_mark */
2391                                  g1_policy()->max_pause_time_ms(),
2392                                  cause);
2393       op.set_allocation_context(AllocationContext::current());
2394 
2395       VMThread::execute(&op);
2396       if (!op.pause_succeeded()) {
2397         if (old_marking_count_before == _old_marking_cycles_started) {
2398           retry_gc = op.should_retry_gc();
2399         } else {
2400           // A Full GC happened while we were trying to schedule the
2401           // initial-mark GC. No point in starting a new cycle given
2402           // that the whole heap was collected anyway.
2403         }
2404 
2405         if (retry_gc) {
2406           if (GC_locker::is_active_and_needs_gc()) {
2407             GC_locker::stall_until_clear();
2408           }
2409         }
2410       }
2411     } else {
2412       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2413           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2414 
2415         // Schedule a standard evacuation pause. We're setting word_size
2416         // to 0 which means that we are not requesting a post-GC allocation.
2417         VM_G1IncCollectionPause op(gc_count_before,
2418                                    0,     /* word_size */
2419                                    false, /* should_initiate_conc_mark */
2420                                    g1_policy()->max_pause_time_ms(),
2421                                    cause);
2422         VMThread::execute(&op);
2423       } else {
2424         // Schedule a Full GC.
2425         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2426         VMThread::execute(&op);
2427       }
2428     }
2429   } while (retry_gc);
2430 }
2431 
2432 bool G1CollectedHeap::is_in(const void* p) const {
2433   if (_hrm.reserved().contains(p)) {
2434     // Given that we know that p is in the reserved space,
2435     // heap_region_containing_raw() should successfully
2436     // return the containing region.
2437     HeapRegion* hr = heap_region_containing_raw(p);
2438     return hr->is_in(p);
2439   } else {
2440     return false;
2441   }
2442 }
2443 
2444 #ifdef ASSERT
2445 bool G1CollectedHeap::is_in_exact(const void* p) const {
2446   bool contains = reserved_region().contains(p);
2447   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2448   if (contains && available) {
2449     return true;
2450   } else {
2451     return false;
2452   }
2453 }
2454 #endif
2455 
2456 // Iteration functions.
2457 
2458 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2459 
2460 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2461   ExtendedOopClosure* _cl;
2462 public:
2463   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2464   bool doHeapRegion(HeapRegion* r) {
2465     if (!r->is_continues_humongous()) {
2466       r->oop_iterate(_cl);
2467     }
2468     return false;
2469   }
2470 };
2471 
2472 // Iterates an ObjectClosure over all objects within a HeapRegion.
2473 
2474 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2475   ObjectClosure* _cl;
2476 public:
2477   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2478   bool doHeapRegion(HeapRegion* r) {
2479     if (!r->is_continues_humongous()) {
2480       r->object_iterate(_cl);
2481     }
2482     return false;
2483   }
2484 };
2485 
2486 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2487   IterateObjectClosureRegionClosure blk(cl);
2488   heap_region_iterate(&blk);
2489 }
2490 
2491 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2492   _hrm.iterate(cl);
2493 }
2494 
2495 void
2496 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2497                                          uint worker_id,
2498                                          HeapRegionClaimer *hrclaimer,
2499                                          bool concurrent) const {
2500   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2501 }
2502 
2503 // Clear the cached CSet starting regions and (more importantly)
2504 // the time stamps. Called when we reset the GC time stamp.
2505 void G1CollectedHeap::clear_cset_start_regions() {
2506   assert(_worker_cset_start_region != NULL, "sanity");
2507   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2508 
2509   int n_queues = MAX2((int)ParallelGCThreads, 1);
2510   for (int i = 0; i < n_queues; i++) {
2511     _worker_cset_start_region[i] = NULL;
2512     _worker_cset_start_region_time_stamp[i] = 0;
2513   }
2514 }
2515 
2516 // Given the id of a worker, obtain or calculate a suitable
2517 // starting region for iterating over the current collection set.
2518 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2519   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2520 
2521   HeapRegion* result = NULL;
2522   unsigned gc_time_stamp = get_gc_time_stamp();
2523 
2524   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2525     // Cached starting region for current worker was set
2526     // during the current pause - so it's valid.
2527     // Note: the cached starting heap region may be NULL
2528     // (when the collection set is empty).
2529     result = _worker_cset_start_region[worker_i];
2530     assert(result == NULL || result->in_collection_set(), "sanity");
2531     return result;
2532   }
2533 
2534   // The cached entry was not valid so let's calculate
2535   // a suitable starting heap region for this worker.
2536 
2537   // We want the parallel threads to start their collection
2538   // set iteration at different collection set regions to
2539   // avoid contention.
2540   // If we have:
2541   //          n collection set regions
2542   //          p threads
2543   // Then thread t will start at region floor ((t * n) / p)
2544 
2545   result = g1_policy()->collection_set();
2546   uint cs_size = g1_policy()->cset_region_length();
2547   uint active_workers = workers()->active_workers();
2548   assert(UseDynamicNumberOfGCThreads ||
2549            active_workers == workers()->total_workers(),
2550            "Unless dynamic should use total workers");
2551 
2552   uint end_ind   = (cs_size * worker_i) / active_workers;
2553   uint start_ind = 0;
2554 
2555   if (worker_i > 0 &&
2556       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2557     // Previous workers starting region is valid
2558     // so let's iterate from there
2559     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2560     result = _worker_cset_start_region[worker_i - 1];
2561   }
2562 
2563   for (uint i = start_ind; i < end_ind; i++) {
2564     result = result->next_in_collection_set();
2565   }
2566 
2567   // Note: the calculated starting heap region may be NULL
2568   // (when the collection set is empty).
2569   assert(result == NULL || result->in_collection_set(), "sanity");
2570   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2571          "should be updated only once per pause");
2572   _worker_cset_start_region[worker_i] = result;
2573   OrderAccess::storestore();
2574   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2575   return result;
2576 }
2577 
2578 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2579   HeapRegion* r = g1_policy()->collection_set();
2580   while (r != NULL) {
2581     HeapRegion* next = r->next_in_collection_set();
2582     if (cl->doHeapRegion(r)) {
2583       cl->incomplete();
2584       return;
2585     }
2586     r = next;
2587   }
2588 }
2589 
2590 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2591                                                   HeapRegionClosure *cl) {
2592   if (r == NULL) {
2593     // The CSet is empty so there's nothing to do.
2594     return;
2595   }
2596 
2597   assert(r->in_collection_set(),
2598          "Start region must be a member of the collection set.");
2599   HeapRegion* cur = r;
2600   while (cur != NULL) {
2601     HeapRegion* next = cur->next_in_collection_set();
2602     if (cl->doHeapRegion(cur) && false) {
2603       cl->incomplete();
2604       return;
2605     }
2606     cur = next;
2607   }
2608   cur = g1_policy()->collection_set();
2609   while (cur != r) {
2610     HeapRegion* next = cur->next_in_collection_set();
2611     if (cl->doHeapRegion(cur) && false) {
2612       cl->incomplete();
2613       return;
2614     }
2615     cur = next;
2616   }
2617 }
2618 
2619 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2620   HeapRegion* result = _hrm.next_region_in_heap(from);
2621   while (result != NULL && result->is_humongous()) {
2622     result = _hrm.next_region_in_heap(result);
2623   }
2624   return result;
2625 }
2626 
2627 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2628   HeapRegion* hr = heap_region_containing(addr);
2629   return hr->block_start(addr);
2630 }
2631 
2632 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2633   HeapRegion* hr = heap_region_containing(addr);
2634   return hr->block_size(addr);
2635 }
2636 
2637 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2638   HeapRegion* hr = heap_region_containing(addr);
2639   return hr->block_is_obj(addr);
2640 }
2641 
2642 bool G1CollectedHeap::supports_tlab_allocation() const {
2643   return true;
2644 }
2645 
2646 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2647   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2648 }
2649 
2650 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2651   return young_list()->eden_used_bytes();
2652 }
2653 
2654 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2655 // must be smaller than the humongous object limit.
2656 size_t G1CollectedHeap::max_tlab_size() const {
2657   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2658 }
2659 
2660 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2661   // Return the remaining space in the cur alloc region, but not less than
2662   // the min TLAB size.
2663 
2664   // Also, this value can be at most the humongous object threshold,
2665   // since we can't allow tlabs to grow big enough to accommodate
2666   // humongous objects.
2667 
2668   HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2669   size_t max_tlab = max_tlab_size() * wordSize;
2670   if (hr == NULL) {
2671     return max_tlab;
2672   } else {
2673     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2674   }
2675 }
2676 
2677 size_t G1CollectedHeap::max_capacity() const {
2678   return _hrm.reserved().byte_size();
2679 }
2680 
2681 jlong G1CollectedHeap::millis_since_last_gc() {
2682   // assert(false, "NYI");
2683   return 0;
2684 }
2685 
2686 void G1CollectedHeap::prepare_for_verify() {
2687   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2688     ensure_parsability(false);
2689   }
2690   g1_rem_set()->prepare_for_verify();
2691 }
2692 
2693 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2694                                               VerifyOption vo) {
2695   switch (vo) {
2696   case VerifyOption_G1UsePrevMarking:
2697     return hr->obj_allocated_since_prev_marking(obj);
2698   case VerifyOption_G1UseNextMarking:
2699     return hr->obj_allocated_since_next_marking(obj);
2700   case VerifyOption_G1UseMarkWord:
2701     return false;
2702   default:
2703     ShouldNotReachHere();
2704   }
2705   return false; // keep some compilers happy
2706 }
2707 
2708 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2709   switch (vo) {
2710   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2711   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2712   case VerifyOption_G1UseMarkWord:    return NULL;
2713   default:                            ShouldNotReachHere();
2714   }
2715   return NULL; // keep some compilers happy
2716 }
2717 
2718 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2719   switch (vo) {
2720   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2721   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2722   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2723   default:                            ShouldNotReachHere();
2724   }
2725   return false; // keep some compilers happy
2726 }
2727 
2728 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2729   switch (vo) {
2730   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2731   case VerifyOption_G1UseNextMarking: return "NTAMS";
2732   case VerifyOption_G1UseMarkWord:    return "NONE";
2733   default:                            ShouldNotReachHere();
2734   }
2735   return NULL; // keep some compilers happy
2736 }
2737 
2738 class VerifyRootsClosure: public OopClosure {
2739 private:
2740   G1CollectedHeap* _g1h;
2741   VerifyOption     _vo;
2742   bool             _failures;
2743 public:
2744   // _vo == UsePrevMarking -> use "prev" marking information,
2745   // _vo == UseNextMarking -> use "next" marking information,
2746   // _vo == UseMarkWord    -> use mark word from object header.
2747   VerifyRootsClosure(VerifyOption vo) :
2748     _g1h(G1CollectedHeap::heap()),
2749     _vo(vo),
2750     _failures(false) { }
2751 
2752   bool failures() { return _failures; }
2753 
2754   template <class T> void do_oop_nv(T* p) {
2755     T heap_oop = oopDesc::load_heap_oop(p);
2756     if (!oopDesc::is_null(heap_oop)) {
2757       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2758       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2759         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2760                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2761         if (_vo == VerifyOption_G1UseMarkWord) {
2762           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2763         }
2764         obj->print_on(gclog_or_tty);
2765         _failures = true;
2766       }
2767     }
2768   }
2769 
2770   void do_oop(oop* p)       { do_oop_nv(p); }
2771   void do_oop(narrowOop* p) { do_oop_nv(p); }
2772 };
2773 
2774 class G1VerifyCodeRootOopClosure: public OopClosure {
2775   G1CollectedHeap* _g1h;
2776   OopClosure* _root_cl;
2777   nmethod* _nm;
2778   VerifyOption _vo;
2779   bool _failures;
2780 
2781   template <class T> void do_oop_work(T* p) {
2782     // First verify that this root is live
2783     _root_cl->do_oop(p);
2784 
2785     if (!G1VerifyHeapRegionCodeRoots) {
2786       // We're not verifying the code roots attached to heap region.
2787       return;
2788     }
2789 
2790     // Don't check the code roots during marking verification in a full GC
2791     if (_vo == VerifyOption_G1UseMarkWord) {
2792       return;
2793     }
2794 
2795     // Now verify that the current nmethod (which contains p) is
2796     // in the code root list of the heap region containing the
2797     // object referenced by p.
2798 
2799     T heap_oop = oopDesc::load_heap_oop(p);
2800     if (!oopDesc::is_null(heap_oop)) {
2801       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2802 
2803       // Now fetch the region containing the object
2804       HeapRegion* hr = _g1h->heap_region_containing(obj);
2805       HeapRegionRemSet* hrrs = hr->rem_set();
2806       // Verify that the strong code root list for this region
2807       // contains the nmethod
2808       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2809         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2810                               "from nmethod "PTR_FORMAT" not in strong "
2811                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2812                               p, _nm, hr->bottom(), hr->end());
2813         _failures = true;
2814       }
2815     }
2816   }
2817 
2818 public:
2819   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2820     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2821 
2822   void do_oop(oop* p) { do_oop_work(p); }
2823   void do_oop(narrowOop* p) { do_oop_work(p); }
2824 
2825   void set_nmethod(nmethod* nm) { _nm = nm; }
2826   bool failures() { return _failures; }
2827 };
2828 
2829 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2830   G1VerifyCodeRootOopClosure* _oop_cl;
2831 
2832 public:
2833   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2834     _oop_cl(oop_cl) {}
2835 
2836   void do_code_blob(CodeBlob* cb) {
2837     nmethod* nm = cb->as_nmethod_or_null();
2838     if (nm != NULL) {
2839       _oop_cl->set_nmethod(nm);
2840       nm->oops_do(_oop_cl);
2841     }
2842   }
2843 };
2844 
2845 class YoungRefCounterClosure : public OopClosure {
2846   G1CollectedHeap* _g1h;
2847   int              _count;
2848  public:
2849   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2850   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2851   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2852 
2853   int count() { return _count; }
2854   void reset_count() { _count = 0; };
2855 };
2856 
2857 class VerifyKlassClosure: public KlassClosure {
2858   YoungRefCounterClosure _young_ref_counter_closure;
2859   OopClosure *_oop_closure;
2860  public:
2861   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2862   void do_klass(Klass* k) {
2863     k->oops_do(_oop_closure);
2864 
2865     _young_ref_counter_closure.reset_count();
2866     k->oops_do(&_young_ref_counter_closure);
2867     if (_young_ref_counter_closure.count() > 0) {
2868       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2869     }
2870   }
2871 };
2872 
2873 class VerifyLivenessOopClosure: public OopClosure {
2874   G1CollectedHeap* _g1h;
2875   VerifyOption _vo;
2876 public:
2877   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2878     _g1h(g1h), _vo(vo)
2879   { }
2880   void do_oop(narrowOop *p) { do_oop_work(p); }
2881   void do_oop(      oop *p) { do_oop_work(p); }
2882 
2883   template <class T> void do_oop_work(T *p) {
2884     oop obj = oopDesc::load_decode_heap_oop(p);
2885     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2886               "Dead object referenced by a not dead object");
2887   }
2888 };
2889 
2890 class VerifyObjsInRegionClosure: public ObjectClosure {
2891 private:
2892   G1CollectedHeap* _g1h;
2893   size_t _live_bytes;
2894   HeapRegion *_hr;
2895   VerifyOption _vo;
2896 public:
2897   // _vo == UsePrevMarking -> use "prev" marking information,
2898   // _vo == UseNextMarking -> use "next" marking information,
2899   // _vo == UseMarkWord    -> use mark word from object header.
2900   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2901     : _live_bytes(0), _hr(hr), _vo(vo) {
2902     _g1h = G1CollectedHeap::heap();
2903   }
2904   void do_object(oop o) {
2905     VerifyLivenessOopClosure isLive(_g1h, _vo);
2906     assert(o != NULL, "Huh?");
2907     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2908       // If the object is alive according to the mark word,
2909       // then verify that the marking information agrees.
2910       // Note we can't verify the contra-positive of the
2911       // above: if the object is dead (according to the mark
2912       // word), it may not be marked, or may have been marked
2913       // but has since became dead, or may have been allocated
2914       // since the last marking.
2915       if (_vo == VerifyOption_G1UseMarkWord) {
2916         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2917       }
2918 
2919       o->oop_iterate_no_header(&isLive);
2920       if (!_hr->obj_allocated_since_prev_marking(o)) {
2921         size_t obj_size = o->size();    // Make sure we don't overflow
2922         _live_bytes += (obj_size * HeapWordSize);
2923       }
2924     }
2925   }
2926   size_t live_bytes() { return _live_bytes; }
2927 };
2928 
2929 class PrintObjsInRegionClosure : public ObjectClosure {
2930   HeapRegion *_hr;
2931   G1CollectedHeap *_g1;
2932 public:
2933   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2934     _g1 = G1CollectedHeap::heap();
2935   };
2936 
2937   void do_object(oop o) {
2938     if (o != NULL) {
2939       HeapWord *start = (HeapWord *) o;
2940       size_t word_sz = o->size();
2941       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2942                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2943                           (void*) o, word_sz,
2944                           _g1->isMarkedPrev(o),
2945                           _g1->isMarkedNext(o),
2946                           _hr->obj_allocated_since_prev_marking(o));
2947       HeapWord *end = start + word_sz;
2948       HeapWord *cur;
2949       int *val;
2950       for (cur = start; cur < end; cur++) {
2951         val = (int *) cur;
2952         gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2953       }
2954     }
2955   }
2956 };
2957 
2958 class VerifyRegionClosure: public HeapRegionClosure {
2959 private:
2960   bool             _par;
2961   VerifyOption     _vo;
2962   bool             _failures;
2963 public:
2964   // _vo == UsePrevMarking -> use "prev" marking information,
2965   // _vo == UseNextMarking -> use "next" marking information,
2966   // _vo == UseMarkWord    -> use mark word from object header.
2967   VerifyRegionClosure(bool par, VerifyOption vo)
2968     : _par(par),
2969       _vo(vo),
2970       _failures(false) {}
2971 
2972   bool failures() {
2973     return _failures;
2974   }
2975 
2976   bool doHeapRegion(HeapRegion* r) {
2977     if (!r->is_continues_humongous()) {
2978       bool failures = false;
2979       r->verify(_vo, &failures);
2980       if (failures) {
2981         _failures = true;
2982       } else {
2983         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2984         r->object_iterate(&not_dead_yet_cl);
2985         if (_vo != VerifyOption_G1UseNextMarking) {
2986           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2987             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2988                                    "max_live_bytes "SIZE_FORMAT" "
2989                                    "< calculated "SIZE_FORMAT,
2990                                    r->bottom(), r->end(),
2991                                    r->max_live_bytes(),
2992                                  not_dead_yet_cl.live_bytes());
2993             _failures = true;
2994           }
2995         } else {
2996           // When vo == UseNextMarking we cannot currently do a sanity
2997           // check on the live bytes as the calculation has not been
2998           // finalized yet.
2999         }
3000       }
3001     }
3002     return false; // stop the region iteration if we hit a failure
3003   }
3004 };
3005 
3006 // This is the task used for parallel verification of the heap regions
3007 
3008 class G1ParVerifyTask: public AbstractGangTask {
3009 private:
3010   G1CollectedHeap*  _g1h;
3011   VerifyOption      _vo;
3012   bool              _failures;
3013   HeapRegionClaimer _hrclaimer;
3014 
3015 public:
3016   // _vo == UsePrevMarking -> use "prev" marking information,
3017   // _vo == UseNextMarking -> use "next" marking information,
3018   // _vo == UseMarkWord    -> use mark word from object header.
3019   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3020       AbstractGangTask("Parallel verify task"),
3021       _g1h(g1h),
3022       _vo(vo),
3023       _failures(false),
3024       _hrclaimer(g1h->workers()->active_workers()) {}
3025 
3026   bool failures() {
3027     return _failures;
3028   }
3029 
3030   void work(uint worker_id) {
3031     HandleMark hm;
3032     VerifyRegionClosure blk(true, _vo);
3033     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3034     if (blk.failures()) {
3035       _failures = true;
3036     }
3037   }
3038 };
3039 
3040 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3041   if (SafepointSynchronize::is_at_safepoint()) {
3042     assert(Thread::current()->is_VM_thread(),
3043            "Expected to be executed serially by the VM thread at this point");
3044 
3045     if (!silent) { gclog_or_tty->print("Roots "); }
3046     VerifyRootsClosure rootsCl(vo);
3047     VerifyKlassClosure klassCl(this, &rootsCl);
3048     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3049 
3050     // We apply the relevant closures to all the oops in the
3051     // system dictionary, class loader data graph, the string table
3052     // and the nmethods in the code cache.
3053     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3054     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3055 
3056     {
3057       G1RootProcessor root_processor(this);
3058       root_processor.process_all_roots(&rootsCl,
3059                                        &cldCl,
3060                                        &blobsCl);
3061     }
3062 
3063     bool failures = rootsCl.failures() || codeRootsCl.failures();
3064 
3065     if (vo != VerifyOption_G1UseMarkWord) {
3066       // If we're verifying during a full GC then the region sets
3067       // will have been torn down at the start of the GC. Therefore
3068       // verifying the region sets will fail. So we only verify
3069       // the region sets when not in a full GC.
3070       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3071       verify_region_sets();
3072     }
3073 
3074     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3075     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3076 
3077       G1ParVerifyTask task(this, vo);
3078       assert(UseDynamicNumberOfGCThreads ||
3079         workers()->active_workers() == workers()->total_workers(),
3080         "If not dynamic should be using all the workers");
3081       int n_workers = workers()->active_workers();
3082       set_par_threads(n_workers);
3083       workers()->run_task(&task);
3084       set_par_threads(0);
3085       if (task.failures()) {
3086         failures = true;
3087       }
3088 
3089     } else {
3090       VerifyRegionClosure blk(false, vo);
3091       heap_region_iterate(&blk);
3092       if (blk.failures()) {
3093         failures = true;
3094       }
3095     }
3096 
3097     if (G1StringDedup::is_enabled()) {
3098       if (!silent) gclog_or_tty->print("StrDedup ");
3099       G1StringDedup::verify();
3100     }
3101 
3102     if (failures) {
3103       gclog_or_tty->print_cr("Heap:");
3104       // It helps to have the per-region information in the output to
3105       // help us track down what went wrong. This is why we call
3106       // print_extended_on() instead of print_on().
3107       print_extended_on(gclog_or_tty);
3108       gclog_or_tty->cr();
3109 #ifndef PRODUCT
3110       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3111         concurrent_mark()->print_reachable("at-verification-failure",
3112                                            vo, false /* all */);
3113       }
3114 #endif
3115       gclog_or_tty->flush();
3116     }
3117     guarantee(!failures, "there should not have been any failures");
3118   } else {
3119     if (!silent) {
3120       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3121       if (G1StringDedup::is_enabled()) {
3122         gclog_or_tty->print(", StrDedup");
3123       }
3124       gclog_or_tty->print(") ");
3125     }
3126   }
3127 }
3128 
3129 void G1CollectedHeap::verify(bool silent) {
3130   verify(silent, VerifyOption_G1UsePrevMarking);
3131 }
3132 
3133 double G1CollectedHeap::verify(bool guard, const char* msg) {
3134   double verify_time_ms = 0.0;
3135 
3136   if (guard && total_collections() >= VerifyGCStartAt) {
3137     double verify_start = os::elapsedTime();
3138     HandleMark hm;  // Discard invalid handles created during verification
3139     prepare_for_verify();
3140     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3141     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3142   }
3143 
3144   return verify_time_ms;
3145 }
3146 
3147 void G1CollectedHeap::verify_before_gc() {
3148   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3149   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3150 }
3151 
3152 void G1CollectedHeap::verify_after_gc() {
3153   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3154   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3155 }
3156 
3157 class PrintRegionClosure: public HeapRegionClosure {
3158   outputStream* _st;
3159 public:
3160   PrintRegionClosure(outputStream* st) : _st(st) {}
3161   bool doHeapRegion(HeapRegion* r) {
3162     r->print_on(_st);
3163     return false;
3164   }
3165 };
3166 
3167 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3168                                        const HeapRegion* hr,
3169                                        const VerifyOption vo) const {
3170   switch (vo) {
3171   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3172   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3173   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3174   default:                            ShouldNotReachHere();
3175   }
3176   return false; // keep some compilers happy
3177 }
3178 
3179 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3180                                        const VerifyOption vo) const {
3181   switch (vo) {
3182   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3183   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3184   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3185   default:                            ShouldNotReachHere();
3186   }
3187   return false; // keep some compilers happy
3188 }
3189 
3190 void G1CollectedHeap::print_on(outputStream* st) const {
3191   st->print(" %-20s", "garbage-first heap");
3192   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3193             capacity()/K, used_unlocked()/K);
3194   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3195             _hrm.reserved().start(),
3196             _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3197             _hrm.reserved().end());
3198   st->cr();
3199   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3200   uint young_regions = _young_list->length();
3201   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3202             (size_t) young_regions * HeapRegion::GrainBytes / K);
3203   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3204   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3205             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3206   st->cr();
3207   MetaspaceAux::print_on(st);
3208 }
3209 
3210 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3211   print_on(st);
3212 
3213   // Print the per-region information.
3214   st->cr();
3215   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3216                "HS=humongous(starts), HC=humongous(continues), "
3217                "CS=collection set, F=free, TS=gc time stamp, "
3218                "PTAMS=previous top-at-mark-start, "
3219                "NTAMS=next top-at-mark-start)");
3220   PrintRegionClosure blk(st);
3221   heap_region_iterate(&blk);
3222 }
3223 
3224 void G1CollectedHeap::print_on_error(outputStream* st) const {
3225   this->CollectedHeap::print_on_error(st);
3226 
3227   if (_cm != NULL) {
3228     st->cr();
3229     _cm->print_on_error(st);
3230   }
3231 }
3232 
3233 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3234   workers()->print_worker_threads_on(st);
3235   _cmThread->print_on(st);
3236   st->cr();
3237   _cm->print_worker_threads_on(st);
3238   _cg1r->print_worker_threads_on(st);
3239   if (G1StringDedup::is_enabled()) {
3240     G1StringDedup::print_worker_threads_on(st);
3241   }
3242 }
3243 
3244 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3245   workers()->threads_do(tc);
3246   tc->do_thread(_cmThread);
3247   _cg1r->threads_do(tc);
3248   if (G1StringDedup::is_enabled()) {
3249     G1StringDedup::threads_do(tc);
3250   }
3251 }
3252 
3253 void G1CollectedHeap::print_tracing_info() const {
3254   // We'll overload this to mean "trace GC pause statistics."
3255   if (TraceYoungGenTime || TraceOldGenTime) {
3256     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3257     // to that.
3258     g1_policy()->print_tracing_info();
3259   }
3260   if (G1SummarizeRSetStats) {
3261     g1_rem_set()->print_summary_info();
3262   }
3263   if (G1SummarizeConcMark) {
3264     concurrent_mark()->print_summary_info();
3265   }
3266   g1_policy()->print_yg_surv_rate_info();
3267 }
3268 
3269 #ifndef PRODUCT
3270 // Helpful for debugging RSet issues.
3271 
3272 class PrintRSetsClosure : public HeapRegionClosure {
3273 private:
3274   const char* _msg;
3275   size_t _occupied_sum;
3276 
3277 public:
3278   bool doHeapRegion(HeapRegion* r) {
3279     HeapRegionRemSet* hrrs = r->rem_set();
3280     size_t occupied = hrrs->occupied();
3281     _occupied_sum += occupied;
3282 
3283     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3284                            HR_FORMAT_PARAMS(r));
3285     if (occupied == 0) {
3286       gclog_or_tty->print_cr("  RSet is empty");
3287     } else {
3288       hrrs->print();
3289     }
3290     gclog_or_tty->print_cr("----------");
3291     return false;
3292   }
3293 
3294   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3295     gclog_or_tty->cr();
3296     gclog_or_tty->print_cr("========================================");
3297     gclog_or_tty->print_cr("%s", msg);
3298     gclog_or_tty->cr();
3299   }
3300 
3301   ~PrintRSetsClosure() {
3302     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3303     gclog_or_tty->print_cr("========================================");
3304     gclog_or_tty->cr();
3305   }
3306 };
3307 
3308 void G1CollectedHeap::print_cset_rsets() {
3309   PrintRSetsClosure cl("Printing CSet RSets");
3310   collection_set_iterate(&cl);
3311 }
3312 
3313 void G1CollectedHeap::print_all_rsets() {
3314   PrintRSetsClosure cl("Printing All RSets");;
3315   heap_region_iterate(&cl);
3316 }
3317 #endif // PRODUCT
3318 
3319 G1CollectedHeap* G1CollectedHeap::heap() {
3320   assert(_g1h != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3321   assert(_g1h->kind() == CollectedHeap::G1CollectedHeap, "Not a G1 heap");
3322   return _g1h;
3323 }
3324 
3325 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3326   // always_do_update_barrier = false;
3327   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3328   // Fill TLAB's and such
3329   accumulate_statistics_all_tlabs();
3330   ensure_parsability(true);
3331 
3332   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3333       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3334     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3335   }
3336 }
3337 
3338 void G1CollectedHeap::gc_epilogue(bool full) {
3339 
3340   if (G1SummarizeRSetStats &&
3341       (G1SummarizeRSetStatsPeriod > 0) &&
3342       // we are at the end of the GC. Total collections has already been increased.
3343       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3344     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3345   }
3346 
3347   // FIXME: what is this about?
3348   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3349   // is set.
3350   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3351                         "derived pointer present"));
3352   // always_do_update_barrier = true;
3353 
3354   resize_all_tlabs();
3355   allocation_context_stats().update(full);
3356 
3357   // We have just completed a GC. Update the soft reference
3358   // policy with the new heap occupancy
3359   Universe::update_heap_info_at_gc();
3360 }
3361 
3362 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3363                                                uint gc_count_before,
3364                                                bool* succeeded,
3365                                                GCCause::Cause gc_cause) {
3366   assert_heap_not_locked_and_not_at_safepoint();
3367   g1_policy()->record_stop_world_start();
3368   VM_G1IncCollectionPause op(gc_count_before,
3369                              word_size,
3370                              false, /* should_initiate_conc_mark */
3371                              g1_policy()->max_pause_time_ms(),
3372                              gc_cause);
3373 
3374   op.set_allocation_context(AllocationContext::current());
3375   VMThread::execute(&op);
3376 
3377   HeapWord* result = op.result();
3378   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3379   assert(result == NULL || ret_succeeded,
3380          "the result should be NULL if the VM did not succeed");
3381   *succeeded = ret_succeeded;
3382 
3383   assert_heap_not_locked();
3384   return result;
3385 }
3386 
3387 void
3388 G1CollectedHeap::doConcurrentMark() {
3389   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3390   if (!_cmThread->in_progress()) {
3391     _cmThread->set_started();
3392     CGC_lock->notify();
3393   }
3394 }
3395 
3396 size_t G1CollectedHeap::pending_card_num() {
3397   size_t extra_cards = 0;
3398   JavaThread *curr = Threads::first();
3399   while (curr != NULL) {
3400     DirtyCardQueue& dcq = curr->dirty_card_queue();
3401     extra_cards += dcq.size();
3402     curr = curr->next();
3403   }
3404   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3405   size_t buffer_size = dcqs.buffer_size();
3406   size_t buffer_num = dcqs.completed_buffers_num();
3407 
3408   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3409   // in bytes - not the number of 'entries'. We need to convert
3410   // into a number of cards.
3411   return (buffer_size * buffer_num + extra_cards) / oopSize;
3412 }
3413 
3414 size_t G1CollectedHeap::cards_scanned() {
3415   return g1_rem_set()->cardsScanned();
3416 }
3417 
3418 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3419   HeapRegion* region = region_at(index);
3420   assert(region->is_starts_humongous(), "Must start a humongous object");
3421   return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3422 }
3423 
3424 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3425  private:
3426   size_t _total_humongous;
3427   size_t _candidate_humongous;
3428 
3429   DirtyCardQueue _dcq;
3430 
3431   bool humongous_region_is_candidate(uint index) {
3432     HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3433     assert(region->is_starts_humongous(), "Must start a humongous object");
3434     HeapRegionRemSet* const rset = region->rem_set();
3435     bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3436     return !oop(region->bottom())->is_objArray() &&
3437            ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3438             (!allow_stale_refs && rset->is_empty()));
3439   }
3440 
3441  public:
3442   RegisterHumongousWithInCSetFastTestClosure()
3443   : _total_humongous(0),
3444     _candidate_humongous(0),
3445     _dcq(&JavaThread::dirty_card_queue_set()) {
3446   }
3447 
3448   virtual bool doHeapRegion(HeapRegion* r) {
3449     if (!r->is_starts_humongous()) {
3450       return false;
3451     }
3452     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3453 
3454     uint region_idx = r->hrm_index();
3455     bool is_candidate = humongous_region_is_candidate(region_idx);
3456     // Is_candidate already filters out humongous object with large remembered sets.
3457     // If we have a humongous object with a few remembered sets, we simply flush these
3458     // remembered set entries into the DCQS. That will result in automatic
3459     // re-evaluation of their remembered set entries during the following evacuation
3460     // phase.
3461     if (is_candidate) {
3462       if (!r->rem_set()->is_empty()) {
3463         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3464                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3465         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3466         HeapRegionRemSetIterator hrrs(r->rem_set());
3467         size_t card_index;
3468         while (hrrs.has_next(card_index)) {
3469           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3470           // The remembered set might contain references to already freed
3471           // regions. Filter out such entries to avoid failing card table
3472           // verification.
3473           if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3474             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3475               *card_ptr = CardTableModRefBS::dirty_card_val();
3476               _dcq.enqueue(card_ptr);
3477             }
3478           }
3479         }
3480         r->rem_set()->clear_locked();
3481       }
3482       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3483       g1h->register_humongous_region_with_cset(region_idx);
3484       _candidate_humongous++;
3485     }
3486     _total_humongous++;
3487 
3488     return false;
3489   }
3490 
3491   size_t total_humongous() const { return _total_humongous; }
3492   size_t candidate_humongous() const { return _candidate_humongous; }
3493 
3494   void flush_rem_set_entries() { _dcq.flush(); }
3495 };
3496 
3497 void G1CollectedHeap::register_humongous_regions_with_cset() {
3498   if (!G1EagerReclaimHumongousObjects) {
3499     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3500     return;
3501   }
3502   double time = os::elapsed_counter();
3503 
3504   RegisterHumongousWithInCSetFastTestClosure cl;
3505   heap_region_iterate(&cl);
3506 
3507   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3508   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3509                                                                   cl.total_humongous(),
3510                                                                   cl.candidate_humongous());
3511   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3512 
3513   if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3514     clear_humongous_is_live_table();
3515   }
3516 
3517   // Finally flush all remembered set entries to re-check into the global DCQS.
3518   cl.flush_rem_set_entries();
3519 }
3520 
3521 void
3522 G1CollectedHeap::setup_surviving_young_words() {
3523   assert(_surviving_young_words == NULL, "pre-condition");
3524   uint array_length = g1_policy()->young_cset_region_length();
3525   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3526   if (_surviving_young_words == NULL) {
3527     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3528                           "Not enough space for young surv words summary.");
3529   }
3530   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3531 #ifdef ASSERT
3532   for (uint i = 0;  i < array_length; ++i) {
3533     assert( _surviving_young_words[i] == 0, "memset above" );
3534   }
3535 #endif // !ASSERT
3536 }
3537 
3538 void
3539 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3540   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3541   uint array_length = g1_policy()->young_cset_region_length();
3542   for (uint i = 0; i < array_length; ++i) {
3543     _surviving_young_words[i] += surv_young_words[i];
3544   }
3545 }
3546 
3547 void
3548 G1CollectedHeap::cleanup_surviving_young_words() {
3549   guarantee( _surviving_young_words != NULL, "pre-condition" );
3550   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3551   _surviving_young_words = NULL;
3552 }
3553 
3554 #ifdef ASSERT
3555 class VerifyCSetClosure: public HeapRegionClosure {
3556 public:
3557   bool doHeapRegion(HeapRegion* hr) {
3558     // Here we check that the CSet region's RSet is ready for parallel
3559     // iteration. The fields that we'll verify are only manipulated
3560     // when the region is part of a CSet and is collected. Afterwards,
3561     // we reset these fields when we clear the region's RSet (when the
3562     // region is freed) so they are ready when the region is
3563     // re-allocated. The only exception to this is if there's an
3564     // evacuation failure and instead of freeing the region we leave
3565     // it in the heap. In that case, we reset these fields during
3566     // evacuation failure handling.
3567     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3568 
3569     // Here's a good place to add any other checks we'd like to
3570     // perform on CSet regions.
3571     return false;
3572   }
3573 };
3574 #endif // ASSERT
3575 
3576 #if TASKQUEUE_STATS
3577 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3578   st->print_raw_cr("GC Task Stats");
3579   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3580   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3581 }
3582 
3583 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3584   print_taskqueue_stats_hdr(st);
3585 
3586   TaskQueueStats totals;
3587   const int n = workers()->total_workers();
3588   for (int i = 0; i < n; ++i) {
3589     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3590     totals += task_queue(i)->stats;
3591   }
3592   st->print_raw("tot "); totals.print(st); st->cr();
3593 
3594   DEBUG_ONLY(totals.verify());
3595 }
3596 
3597 void G1CollectedHeap::reset_taskqueue_stats() {
3598   const int n = workers()->total_workers();
3599   for (int i = 0; i < n; ++i) {
3600     task_queue(i)->stats.reset();
3601   }
3602 }
3603 #endif // TASKQUEUE_STATS
3604 
3605 void G1CollectedHeap::log_gc_header() {
3606   if (!G1Log::fine()) {
3607     return;
3608   }
3609 
3610   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3611 
3612   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3613     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3614     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3615 
3616   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3617 }
3618 
3619 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3620   if (!G1Log::fine()) {
3621     return;
3622   }
3623 
3624   if (G1Log::finer()) {
3625     if (evacuation_failed()) {
3626       gclog_or_tty->print(" (to-space exhausted)");
3627     }
3628     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3629     g1_policy()->phase_times()->note_gc_end();
3630     g1_policy()->phase_times()->print(pause_time_sec);
3631     g1_policy()->print_detailed_heap_transition();
3632   } else {
3633     if (evacuation_failed()) {
3634       gclog_or_tty->print("--");
3635     }
3636     g1_policy()->print_heap_transition();
3637     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3638   }
3639   gclog_or_tty->flush();
3640 }
3641 
3642 bool
3643 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3644   assert_at_safepoint(true /* should_be_vm_thread */);
3645   guarantee(!is_gc_active(), "collection is not reentrant");
3646 
3647   if (GC_locker::check_active_before_gc()) {
3648     return false;
3649   }
3650 
3651   _gc_timer_stw->register_gc_start();
3652 
3653   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3654 
3655   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3656   ResourceMark rm;
3657 
3658   print_heap_before_gc();
3659   trace_heap_before_gc(_gc_tracer_stw);
3660 
3661   verify_region_sets_optional();
3662   verify_dirty_young_regions();
3663 
3664   // This call will decide whether this pause is an initial-mark
3665   // pause. If it is, during_initial_mark_pause() will return true
3666   // for the duration of this pause.
3667   g1_policy()->decide_on_conc_mark_initiation();
3668 
3669   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3670   assert(!g1_policy()->during_initial_mark_pause() ||
3671           g1_policy()->gcs_are_young(), "sanity");
3672 
3673   // We also do not allow mixed GCs during marking.
3674   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3675 
3676   // Record whether this pause is an initial mark. When the current
3677   // thread has completed its logging output and it's safe to signal
3678   // the CM thread, the flag's value in the policy has been reset.
3679   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3680 
3681   // Inner scope for scope based logging, timers, and stats collection
3682   {
3683     EvacuationInfo evacuation_info;
3684 
3685     if (g1_policy()->during_initial_mark_pause()) {
3686       // We are about to start a marking cycle, so we increment the
3687       // full collection counter.
3688       increment_old_marking_cycles_started();
3689       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3690     }
3691 
3692     _gc_tracer_stw->report_yc_type(yc_type());
3693 
3694     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3695 
3696     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3697                                                                   workers()->active_workers(),
3698                                                                   Threads::number_of_non_daemon_threads());
3699     assert(UseDynamicNumberOfGCThreads ||
3700            active_workers == workers()->total_workers(),
3701            "If not dynamic should be using all the  workers");
3702     workers()->set_active_workers(active_workers);
3703 
3704     double pause_start_sec = os::elapsedTime();
3705     g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3706     log_gc_header();
3707 
3708     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3709     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3710 
3711     // If the secondary_free_list is not empty, append it to the
3712     // free_list. No need to wait for the cleanup operation to finish;
3713     // the region allocation code will check the secondary_free_list
3714     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3715     // set, skip this step so that the region allocation code has to
3716     // get entries from the secondary_free_list.
3717     if (!G1StressConcRegionFreeing) {
3718       append_secondary_free_list_if_not_empty_with_lock();
3719     }
3720 
3721     assert(check_young_list_well_formed(), "young list should be well formed");
3722 
3723     // Don't dynamically change the number of GC threads this early.  A value of
3724     // 0 is used to indicate serial work.  When parallel work is done,
3725     // it will be set.
3726 
3727     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3728       IsGCActiveMark x;
3729 
3730       gc_prologue(false);
3731       increment_total_collections(false /* full gc */);
3732       increment_gc_time_stamp();
3733 
3734       verify_before_gc();
3735 
3736       check_bitmaps("GC Start");
3737 
3738       COMPILER2_PRESENT(DerivedPointerTable::clear());
3739 
3740       // Please see comment in g1CollectedHeap.hpp and
3741       // G1CollectedHeap::ref_processing_init() to see how
3742       // reference processing currently works in G1.
3743 
3744       // Enable discovery in the STW reference processor
3745       ref_processor_stw()->enable_discovery();
3746 
3747       {
3748         // We want to temporarily turn off discovery by the
3749         // CM ref processor, if necessary, and turn it back on
3750         // on again later if we do. Using a scoped
3751         // NoRefDiscovery object will do this.
3752         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3753 
3754         // Forget the current alloc region (we might even choose it to be part
3755         // of the collection set!).
3756         _allocator->release_mutator_alloc_region();
3757 
3758         // We should call this after we retire the mutator alloc
3759         // region(s) so that all the ALLOC / RETIRE events are generated
3760         // before the start GC event.
3761         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3762 
3763         // This timing is only used by the ergonomics to handle our pause target.
3764         // It is unclear why this should not include the full pause. We will
3765         // investigate this in CR 7178365.
3766         //
3767         // Preserving the old comment here if that helps the investigation:
3768         //
3769         // The elapsed time induced by the start time below deliberately elides
3770         // the possible verification above.
3771         double sample_start_time_sec = os::elapsedTime();
3772 
3773 #if YOUNG_LIST_VERBOSE
3774         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3775         _young_list->print();
3776         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3777 #endif // YOUNG_LIST_VERBOSE
3778 
3779         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3780 
3781         double scan_wait_start = os::elapsedTime();
3782         // We have to wait until the CM threads finish scanning the
3783         // root regions as it's the only way to ensure that all the
3784         // objects on them have been correctly scanned before we start
3785         // moving them during the GC.
3786         bool waited = _cm->root_regions()->wait_until_scan_finished();
3787         double wait_time_ms = 0.0;
3788         if (waited) {
3789           double scan_wait_end = os::elapsedTime();
3790           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3791         }
3792         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3793 
3794 #if YOUNG_LIST_VERBOSE
3795         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3796         _young_list->print();
3797 #endif // YOUNG_LIST_VERBOSE
3798 
3799         if (g1_policy()->during_initial_mark_pause()) {
3800           concurrent_mark()->checkpointRootsInitialPre();
3801         }
3802 
3803 #if YOUNG_LIST_VERBOSE
3804         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3805         _young_list->print();
3806         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3807 #endif // YOUNG_LIST_VERBOSE
3808 
3809         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3810 
3811         register_humongous_regions_with_cset();
3812 
3813         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3814 
3815         _cm->note_start_of_gc();
3816         // We should not verify the per-thread SATB buffers given that
3817         // we have not filtered them yet (we'll do so during the
3818         // GC). We also call this after finalize_cset() to
3819         // ensure that the CSet has been finalized.
3820         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3821                                  true  /* verify_enqueued_buffers */,
3822                                  false /* verify_thread_buffers */,
3823                                  true  /* verify_fingers */);
3824 
3825         if (_hr_printer.is_active()) {
3826           HeapRegion* hr = g1_policy()->collection_set();
3827           while (hr != NULL) {
3828             _hr_printer.cset(hr);
3829             hr = hr->next_in_collection_set();
3830           }
3831         }
3832 
3833 #ifdef ASSERT
3834         VerifyCSetClosure cl;
3835         collection_set_iterate(&cl);
3836 #endif // ASSERT
3837 
3838         setup_surviving_young_words();
3839 
3840         // Initialize the GC alloc regions.
3841         _allocator->init_gc_alloc_regions(evacuation_info);
3842 
3843         // Actually do the work...
3844         evacuate_collection_set(evacuation_info);
3845 
3846         // We do this to mainly verify the per-thread SATB buffers
3847         // (which have been filtered by now) since we didn't verify
3848         // them earlier. No point in re-checking the stacks / enqueued
3849         // buffers given that the CSet has not changed since last time
3850         // we checked.
3851         _cm->verify_no_cset_oops(false /* verify_stacks */,
3852                                  false /* verify_enqueued_buffers */,
3853                                  true  /* verify_thread_buffers */,
3854                                  true  /* verify_fingers */);
3855 
3856         free_collection_set(g1_policy()->collection_set(), evacuation_info);
3857 
3858         eagerly_reclaim_humongous_regions();
3859 
3860         g1_policy()->clear_collection_set();
3861 
3862         cleanup_surviving_young_words();
3863 
3864         // Start a new incremental collection set for the next pause.
3865         g1_policy()->start_incremental_cset_building();
3866 
3867         clear_cset_fast_test();
3868 
3869         _young_list->reset_sampled_info();
3870 
3871         // Don't check the whole heap at this point as the
3872         // GC alloc regions from this pause have been tagged
3873         // as survivors and moved on to the survivor list.
3874         // Survivor regions will fail the !is_young() check.
3875         assert(check_young_list_empty(false /* check_heap */),
3876           "young list should be empty");
3877 
3878 #if YOUNG_LIST_VERBOSE
3879         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3880         _young_list->print();
3881 #endif // YOUNG_LIST_VERBOSE
3882 
3883         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3884                                              _young_list->first_survivor_region(),
3885                                              _young_list->last_survivor_region());
3886 
3887         _young_list->reset_auxilary_lists();
3888 
3889         if (evacuation_failed()) {
3890           _allocator->set_used(recalculate_used());
3891           uint n_queues = MAX2((int)ParallelGCThreads, 1);
3892           for (uint i = 0; i < n_queues; i++) {
3893             if (_evacuation_failed_info_array[i].has_failed()) {
3894               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3895             }
3896           }
3897         } else {
3898           // The "used" of the the collection set have already been subtracted
3899           // when they were freed.  Add in the bytes evacuated.
3900           _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3901         }
3902 
3903         if (g1_policy()->during_initial_mark_pause()) {
3904           // We have to do this before we notify the CM threads that
3905           // they can start working to make sure that all the
3906           // appropriate initialization is done on the CM object.
3907           concurrent_mark()->checkpointRootsInitialPost();
3908           set_marking_started();
3909           // Note that we don't actually trigger the CM thread at
3910           // this point. We do that later when we're sure that
3911           // the current thread has completed its logging output.
3912         }
3913 
3914         allocate_dummy_regions();
3915 
3916 #if YOUNG_LIST_VERBOSE
3917         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3918         _young_list->print();
3919         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3920 #endif // YOUNG_LIST_VERBOSE
3921 
3922         _allocator->init_mutator_alloc_region();
3923 
3924         {
3925           size_t expand_bytes = g1_policy()->expansion_amount();
3926           if (expand_bytes > 0) {
3927             size_t bytes_before = capacity();
3928             // No need for an ergo verbose message here,
3929             // expansion_amount() does this when it returns a value > 0.
3930             if (!expand(expand_bytes)) {
3931               // We failed to expand the heap. Cannot do anything about it.
3932             }
3933           }
3934         }
3935 
3936         // We redo the verification but now wrt to the new CSet which
3937         // has just got initialized after the previous CSet was freed.
3938         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3939                                  true  /* verify_enqueued_buffers */,
3940                                  true  /* verify_thread_buffers */,
3941                                  true  /* verify_fingers */);
3942         _cm->note_end_of_gc();
3943 
3944         // This timing is only used by the ergonomics to handle our pause target.
3945         // It is unclear why this should not include the full pause. We will
3946         // investigate this in CR 7178365.
3947         double sample_end_time_sec = os::elapsedTime();
3948         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3949         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3950 
3951         MemoryService::track_memory_usage();
3952 
3953         // In prepare_for_verify() below we'll need to scan the deferred
3954         // update buffers to bring the RSets up-to-date if
3955         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3956         // the update buffers we'll probably need to scan cards on the
3957         // regions we just allocated to (i.e., the GC alloc
3958         // regions). However, during the last GC we called
3959         // set_saved_mark() on all the GC alloc regions, so card
3960         // scanning might skip the [saved_mark_word()...top()] area of
3961         // those regions (i.e., the area we allocated objects into
3962         // during the last GC). But it shouldn't. Given that
3963         // saved_mark_word() is conditional on whether the GC time stamp
3964         // on the region is current or not, by incrementing the GC time
3965         // stamp here we invalidate all the GC time stamps on all the
3966         // regions and saved_mark_word() will simply return top() for
3967         // all the regions. This is a nicer way of ensuring this rather
3968         // than iterating over the regions and fixing them. In fact, the
3969         // GC time stamp increment here also ensures that
3970         // saved_mark_word() will return top() between pauses, i.e.,
3971         // during concurrent refinement. So we don't need the
3972         // is_gc_active() check to decided which top to use when
3973         // scanning cards (see CR 7039627).
3974         increment_gc_time_stamp();
3975 
3976         verify_after_gc();
3977         check_bitmaps("GC End");
3978 
3979         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3980         ref_processor_stw()->verify_no_references_recorded();
3981 
3982         // CM reference discovery will be re-enabled if necessary.
3983       }
3984 
3985       // We should do this after we potentially expand the heap so
3986       // that all the COMMIT events are generated before the end GC
3987       // event, and after we retire the GC alloc regions so that all
3988       // RETIRE events are generated before the end GC event.
3989       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3990 
3991 #ifdef TRACESPINNING
3992       ParallelTaskTerminator::print_termination_counts();
3993 #endif
3994 
3995       gc_epilogue(false);
3996     }
3997 
3998     // Print the remainder of the GC log output.
3999     log_gc_footer(os::elapsedTime() - pause_start_sec);
4000 
4001     // It is not yet to safe to tell the concurrent mark to
4002     // start as we have some optional output below. We don't want the
4003     // output from the concurrent mark thread interfering with this
4004     // logging output either.
4005 
4006     _hrm.verify_optional();
4007     verify_region_sets_optional();
4008 
4009     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4010     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4011 
4012     print_heap_after_gc();
4013     trace_heap_after_gc(_gc_tracer_stw);
4014 
4015     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4016     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4017     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4018     // before any GC notifications are raised.
4019     g1mm()->update_sizes();
4020 
4021     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4022     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4023     _gc_timer_stw->register_gc_end();
4024     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4025   }
4026   // It should now be safe to tell the concurrent mark thread to start
4027   // without its logging output interfering with the logging output
4028   // that came from the pause.
4029 
4030   if (should_start_conc_mark) {
4031     // CAUTION: after the doConcurrentMark() call below,
4032     // the concurrent marking thread(s) could be running
4033     // concurrently with us. Make sure that anything after
4034     // this point does not assume that we are the only GC thread
4035     // running. Note: of course, the actual marking work will
4036     // not start until the safepoint itself is released in
4037     // SuspendibleThreadSet::desynchronize().
4038     doConcurrentMark();
4039   }
4040 
4041   return true;
4042 }
4043 
4044 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4045   _drain_in_progress = false;
4046   set_evac_failure_closure(cl);
4047   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4048 }
4049 
4050 void G1CollectedHeap::finalize_for_evac_failure() {
4051   assert(_evac_failure_scan_stack != NULL &&
4052          _evac_failure_scan_stack->length() == 0,
4053          "Postcondition");
4054   assert(!_drain_in_progress, "Postcondition");
4055   delete _evac_failure_scan_stack;
4056   _evac_failure_scan_stack = NULL;
4057 }
4058 
4059 void G1CollectedHeap::remove_self_forwarding_pointers() {
4060   double remove_self_forwards_start = os::elapsedTime();
4061 
4062   set_par_threads();
4063   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4064   workers()->run_task(&rsfp_task);
4065   set_par_threads(0);
4066 
4067   // Now restore saved marks, if any.
4068   assert(_objs_with_preserved_marks.size() ==
4069             _preserved_marks_of_objs.size(), "Both or none.");
4070   while (!_objs_with_preserved_marks.is_empty()) {
4071     oop obj = _objs_with_preserved_marks.pop();
4072     markOop m = _preserved_marks_of_objs.pop();
4073     obj->set_mark(m);
4074   }
4075   _objs_with_preserved_marks.clear(true);
4076   _preserved_marks_of_objs.clear(true);
4077 
4078   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4079 }
4080 
4081 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4082   _evac_failure_scan_stack->push(obj);
4083 }
4084 
4085 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4086   assert(_evac_failure_scan_stack != NULL, "precondition");
4087 
4088   while (_evac_failure_scan_stack->length() > 0) {
4089      oop obj = _evac_failure_scan_stack->pop();
4090      _evac_failure_closure->set_region(heap_region_containing(obj));
4091      obj->oop_iterate_backwards(_evac_failure_closure);
4092   }
4093 }
4094 
4095 oop
4096 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4097                                                oop old) {
4098   assert(obj_in_cs(old),
4099          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4100                  (HeapWord*) old));
4101   markOop m = old->mark();
4102   oop forward_ptr = old->forward_to_atomic(old);
4103   if (forward_ptr == NULL) {
4104     // Forward-to-self succeeded.
4105     assert(_par_scan_state != NULL, "par scan state");
4106     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4107     uint queue_num = _par_scan_state->queue_num();
4108 
4109     _evacuation_failed = true;
4110     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4111     if (_evac_failure_closure != cl) {
4112       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4113       assert(!_drain_in_progress,
4114              "Should only be true while someone holds the lock.");
4115       // Set the global evac-failure closure to the current thread's.
4116       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4117       set_evac_failure_closure(cl);
4118       // Now do the common part.
4119       handle_evacuation_failure_common(old, m);
4120       // Reset to NULL.
4121       set_evac_failure_closure(NULL);
4122     } else {
4123       // The lock is already held, and this is recursive.
4124       assert(_drain_in_progress, "This should only be the recursive case.");
4125       handle_evacuation_failure_common(old, m);
4126     }
4127     return old;
4128   } else {
4129     // Forward-to-self failed. Either someone else managed to allocate
4130     // space for this object (old != forward_ptr) or they beat us in
4131     // self-forwarding it (old == forward_ptr).
4132     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4133            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4134                    "should not be in the CSet",
4135                    (HeapWord*) old, (HeapWord*) forward_ptr));
4136     return forward_ptr;
4137   }
4138 }
4139 
4140 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4141   preserve_mark_if_necessary(old, m);
4142 
4143   HeapRegion* r = heap_region_containing(old);
4144   if (!r->evacuation_failed()) {
4145     r->set_evacuation_failed(true);
4146     _hr_printer.evac_failure(r);
4147   }
4148 
4149   push_on_evac_failure_scan_stack(old);
4150 
4151   if (!_drain_in_progress) {
4152     // prevent recursion in copy_to_survivor_space()
4153     _drain_in_progress = true;
4154     drain_evac_failure_scan_stack();
4155     _drain_in_progress = false;
4156   }
4157 }
4158 
4159 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4160   assert(evacuation_failed(), "Oversaving!");
4161   // We want to call the "for_promotion_failure" version only in the
4162   // case of a promotion failure.
4163   if (m->must_be_preserved_for_promotion_failure(obj)) {
4164     _objs_with_preserved_marks.push(obj);
4165     _preserved_marks_of_objs.push(m);
4166   }
4167 }
4168 
4169 void G1ParCopyHelper::mark_object(oop obj) {
4170   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4171 
4172   // We know that the object is not moving so it's safe to read its size.
4173   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4174 }
4175 
4176 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4177   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4178   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4179   assert(from_obj != to_obj, "should not be self-forwarded");
4180 
4181   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4182   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4183 
4184   // The object might be in the process of being copied by another
4185   // worker so we cannot trust that its to-space image is
4186   // well-formed. So we have to read its size from its from-space
4187   // image which we know should not be changing.
4188   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4189 }
4190 
4191 template <class T>
4192 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4193   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4194     _scanned_klass->record_modified_oops();
4195   }
4196 }
4197 
4198 template <G1Barrier barrier, G1Mark do_mark_object>
4199 template <class T>
4200 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4201   T heap_oop = oopDesc::load_heap_oop(p);
4202 
4203   if (oopDesc::is_null(heap_oop)) {
4204     return;
4205   }
4206 
4207   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4208 
4209   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4210 
4211   const InCSetState state = _g1->in_cset_state(obj);
4212   if (state.is_in_cset()) {
4213     oop forwardee;
4214     markOop m = obj->mark();
4215     if (m->is_marked()) {
4216       forwardee = (oop) m->decode_pointer();
4217     } else {
4218       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4219     }
4220     assert(forwardee != NULL, "forwardee should not be NULL");
4221     oopDesc::encode_store_heap_oop(p, forwardee);
4222     if (do_mark_object != G1MarkNone && forwardee != obj) {
4223       // If the object is self-forwarded we don't need to explicitly
4224       // mark it, the evacuation failure protocol will do so.
4225       mark_forwarded_object(obj, forwardee);
4226     }
4227 
4228     if (barrier == G1BarrierKlass) {
4229       do_klass_barrier(p, forwardee);
4230     }
4231   } else {
4232     if (state.is_humongous()) {
4233       _g1->set_humongous_is_live(obj);
4234     }
4235     // The object is not in collection set. If we're a root scanning
4236     // closure during an initial mark pause then attempt to mark the object.
4237     if (do_mark_object == G1MarkFromRoot) {
4238       mark_object(obj);
4239     }
4240   }
4241 
4242   if (barrier == G1BarrierEvac) {
4243     _par_scan_state->update_rs(_from, p, _worker_id);
4244   }
4245 }
4246 
4247 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4248 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4249 
4250 class G1ParEvacuateFollowersClosure : public VoidClosure {
4251 protected:
4252   G1CollectedHeap*              _g1h;
4253   G1ParScanThreadState*         _par_scan_state;
4254   RefToScanQueueSet*            _queues;
4255   ParallelTaskTerminator*       _terminator;
4256 
4257   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4258   RefToScanQueueSet*      queues()         { return _queues; }
4259   ParallelTaskTerminator* terminator()     { return _terminator; }
4260 
4261 public:
4262   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4263                                 G1ParScanThreadState* par_scan_state,
4264                                 RefToScanQueueSet* queues,
4265                                 ParallelTaskTerminator* terminator)
4266     : _g1h(g1h), _par_scan_state(par_scan_state),
4267       _queues(queues), _terminator(terminator) {}
4268 
4269   void do_void();
4270 
4271 private:
4272   inline bool offer_termination();
4273 };
4274 
4275 bool G1ParEvacuateFollowersClosure::offer_termination() {
4276   G1ParScanThreadState* const pss = par_scan_state();
4277   pss->start_term_time();
4278   const bool res = terminator()->offer_termination();
4279   pss->end_term_time();
4280   return res;
4281 }
4282 
4283 void G1ParEvacuateFollowersClosure::do_void() {
4284   G1ParScanThreadState* const pss = par_scan_state();
4285   pss->trim_queue();
4286   do {
4287     pss->steal_and_trim_queue(queues());
4288   } while (!offer_termination());
4289 }
4290 
4291 class G1KlassScanClosure : public KlassClosure {
4292  G1ParCopyHelper* _closure;
4293  bool             _process_only_dirty;
4294  int              _count;
4295  public:
4296   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4297       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4298   void do_klass(Klass* klass) {
4299     // If the klass has not been dirtied we know that there's
4300     // no references into  the young gen and we can skip it.
4301    if (!_process_only_dirty || klass->has_modified_oops()) {
4302       // Clean the klass since we're going to scavenge all the metadata.
4303       klass->clear_modified_oops();
4304 
4305       // Tell the closure that this klass is the Klass to scavenge
4306       // and is the one to dirty if oops are left pointing into the young gen.
4307       _closure->set_scanned_klass(klass);
4308 
4309       klass->oops_do(_closure);
4310 
4311       _closure->set_scanned_klass(NULL);
4312     }
4313     _count++;
4314   }
4315 };
4316 
4317 class G1ParTask : public AbstractGangTask {
4318 protected:
4319   G1CollectedHeap*       _g1h;
4320   RefToScanQueueSet      *_queues;
4321   G1RootProcessor*       _root_processor;
4322   ParallelTaskTerminator _terminator;
4323   uint _n_workers;
4324 
4325   Mutex _stats_lock;
4326   Mutex* stats_lock() { return &_stats_lock; }
4327 
4328 public:
4329   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4330     : AbstractGangTask("G1 collection"),
4331       _g1h(g1h),
4332       _queues(task_queues),
4333       _root_processor(root_processor),
4334       _terminator(0, _queues),
4335       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4336   {}
4337 
4338   RefToScanQueueSet* queues() { return _queues; }
4339 
4340   RefToScanQueue *work_queue(int i) {
4341     return queues()->queue(i);
4342   }
4343 
4344   ParallelTaskTerminator* terminator() { return &_terminator; }
4345 
4346   virtual void set_for_termination(int active_workers) {
4347     _root_processor->set_num_workers(active_workers);
4348     terminator()->reset_for_reuse(active_workers);
4349     _n_workers = active_workers;
4350   }
4351 
4352   // Helps out with CLD processing.
4353   //
4354   // During InitialMark we need to:
4355   // 1) Scavenge all CLDs for the young GC.
4356   // 2) Mark all objects directly reachable from strong CLDs.
4357   template <G1Mark do_mark_object>
4358   class G1CLDClosure : public CLDClosure {
4359     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4360     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4361     G1KlassScanClosure                                _klass_in_cld_closure;
4362     bool                                              _claim;
4363 
4364    public:
4365     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4366                  bool only_young, bool claim)
4367         : _oop_closure(oop_closure),
4368           _oop_in_klass_closure(oop_closure->g1(),
4369                                 oop_closure->pss(),
4370                                 oop_closure->rp()),
4371           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4372           _claim(claim) {
4373 
4374     }
4375 
4376     void do_cld(ClassLoaderData* cld) {
4377       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4378     }
4379   };
4380 
4381   void work(uint worker_id) {
4382     if (worker_id >= _n_workers) return;  // no work needed this round
4383 
4384     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4385 
4386     {
4387       ResourceMark rm;
4388       HandleMark   hm;
4389 
4390       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4391 
4392       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4393       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4394 
4395       pss.set_evac_failure_closure(&evac_failure_cl);
4396 
4397       bool only_young = _g1h->g1_policy()->gcs_are_young();
4398 
4399       // Non-IM young GC.
4400       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4401       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4402                                                                                only_young, // Only process dirty klasses.
4403                                                                                false);     // No need to claim CLDs.
4404       // IM young GC.
4405       //    Strong roots closures.
4406       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4407       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4408                                                                                false, // Process all klasses.
4409                                                                                true); // Need to claim CLDs.
4410       //    Weak roots closures.
4411       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4412       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4413                                                                                     false, // Process all klasses.
4414                                                                                     true); // Need to claim CLDs.
4415 
4416       OopClosure* strong_root_cl;
4417       OopClosure* weak_root_cl;
4418       CLDClosure* strong_cld_cl;
4419       CLDClosure* weak_cld_cl;
4420 
4421       bool trace_metadata = false;
4422 
4423       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4424         // We also need to mark copied objects.
4425         strong_root_cl = &scan_mark_root_cl;
4426         strong_cld_cl  = &scan_mark_cld_cl;
4427         if (ClassUnloadingWithConcurrentMark) {
4428           weak_root_cl = &scan_mark_weak_root_cl;
4429           weak_cld_cl  = &scan_mark_weak_cld_cl;
4430           trace_metadata = true;
4431         } else {
4432           weak_root_cl = &scan_mark_root_cl;
4433           weak_cld_cl  = &scan_mark_cld_cl;
4434         }
4435       } else {
4436         strong_root_cl = &scan_only_root_cl;
4437         weak_root_cl   = &scan_only_root_cl;
4438         strong_cld_cl  = &scan_only_cld_cl;
4439         weak_cld_cl    = &scan_only_cld_cl;
4440       }
4441 
4442       pss.start_strong_roots();
4443 
4444       _root_processor->evacuate_roots(strong_root_cl,
4445                                       weak_root_cl,
4446                                       strong_cld_cl,
4447                                       weak_cld_cl,
4448                                       trace_metadata,
4449                                       worker_id);
4450 
4451       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4452       _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4453                                             weak_root_cl,
4454                                             worker_id);
4455       pss.end_strong_roots();
4456 
4457       {
4458         double start = os::elapsedTime();
4459         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4460         evac.do_void();
4461         double elapsed_sec = os::elapsedTime() - start;
4462         double term_sec = pss.term_time();
4463         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4464         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4465         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4466       }
4467       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4468       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4469 
4470       if (PrintTerminationStats) {
4471         MutexLocker x(stats_lock());
4472         pss.print_termination_stats(worker_id);
4473       }
4474 
4475       assert(pss.queue_is_empty(), "should be empty");
4476 
4477       // Close the inner scope so that the ResourceMark and HandleMark
4478       // destructors are executed here and are included as part of the
4479       // "GC Worker Time".
4480     }
4481     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4482   }
4483 };
4484 
4485 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4486 private:
4487   BoolObjectClosure* _is_alive;
4488   int _initial_string_table_size;
4489   int _initial_symbol_table_size;
4490 
4491   bool  _process_strings;
4492   int _strings_processed;
4493   int _strings_removed;
4494 
4495   bool  _process_symbols;
4496   int _symbols_processed;
4497   int _symbols_removed;
4498 
4499 public:
4500   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4501     AbstractGangTask("String/Symbol Unlinking"),
4502     _is_alive(is_alive),
4503     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4504     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4505 
4506     _initial_string_table_size = StringTable::the_table()->table_size();
4507     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4508     if (process_strings) {
4509       StringTable::clear_parallel_claimed_index();
4510     }
4511     if (process_symbols) {
4512       SymbolTable::clear_parallel_claimed_index();
4513     }
4514   }
4515 
4516   ~G1StringSymbolTableUnlinkTask() {
4517     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4518               err_msg("claim value %d after unlink less than initial string table size %d",
4519                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4520     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4521               err_msg("claim value %d after unlink less than initial symbol table size %d",
4522                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4523 
4524     if (G1TraceStringSymbolTableScrubbing) {
4525       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4526                              "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4527                              "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4528                              strings_processed(), strings_removed(),
4529                              symbols_processed(), symbols_removed());
4530     }
4531   }
4532 
4533   void work(uint worker_id) {
4534     int strings_processed = 0;
4535     int strings_removed = 0;
4536     int symbols_processed = 0;
4537     int symbols_removed = 0;
4538     if (_process_strings) {
4539       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4540       Atomic::add(strings_processed, &_strings_processed);
4541       Atomic::add(strings_removed, &_strings_removed);
4542     }
4543     if (_process_symbols) {
4544       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4545       Atomic::add(symbols_processed, &_symbols_processed);
4546       Atomic::add(symbols_removed, &_symbols_removed);
4547     }
4548   }
4549 
4550   size_t strings_processed() const { return (size_t)_strings_processed; }
4551   size_t strings_removed()   const { return (size_t)_strings_removed; }
4552 
4553   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4554   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4555 };
4556 
4557 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4558 private:
4559   static Monitor* _lock;
4560 
4561   BoolObjectClosure* const _is_alive;
4562   const bool               _unloading_occurred;
4563   const uint               _num_workers;
4564 
4565   // Variables used to claim nmethods.
4566   nmethod* _first_nmethod;
4567   volatile nmethod* _claimed_nmethod;
4568 
4569   // The list of nmethods that need to be processed by the second pass.
4570   volatile nmethod* _postponed_list;
4571   volatile uint     _num_entered_barrier;
4572 
4573  public:
4574   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4575       _is_alive(is_alive),
4576       _unloading_occurred(unloading_occurred),
4577       _num_workers(num_workers),
4578       _first_nmethod(NULL),
4579       _claimed_nmethod(NULL),
4580       _postponed_list(NULL),
4581       _num_entered_barrier(0)
4582   {
4583     nmethod::increase_unloading_clock();
4584     // Get first alive nmethod
4585     NMethodIterator iter = NMethodIterator();
4586     if(iter.next_alive()) {
4587       _first_nmethod = iter.method();
4588     }
4589     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4590   }
4591 
4592   ~G1CodeCacheUnloadingTask() {
4593     CodeCache::verify_clean_inline_caches();
4594 
4595     CodeCache::set_needs_cache_clean(false);
4596     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4597 
4598     CodeCache::verify_icholder_relocations();
4599   }
4600 
4601  private:
4602   void add_to_postponed_list(nmethod* nm) {
4603       nmethod* old;
4604       do {
4605         old = (nmethod*)_postponed_list;
4606         nm->set_unloading_next(old);
4607       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4608   }
4609 
4610   void clean_nmethod(nmethod* nm) {
4611     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4612 
4613     if (postponed) {
4614       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4615       add_to_postponed_list(nm);
4616     }
4617 
4618     // Mark that this thread has been cleaned/unloaded.
4619     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4620     nm->set_unloading_clock(nmethod::global_unloading_clock());
4621   }
4622 
4623   void clean_nmethod_postponed(nmethod* nm) {
4624     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4625   }
4626 
4627   static const int MaxClaimNmethods = 16;
4628 
4629   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4630     nmethod* first;
4631     NMethodIterator last;
4632 
4633     do {
4634       *num_claimed_nmethods = 0;
4635 
4636       first = (nmethod*)_claimed_nmethod;
4637       last = NMethodIterator(first);
4638 
4639       if (first != NULL) {
4640 
4641         for (int i = 0; i < MaxClaimNmethods; i++) {
4642           if (!last.next_alive()) {
4643             break;
4644           }
4645           claimed_nmethods[i] = last.method();
4646           (*num_claimed_nmethods)++;
4647         }
4648       }
4649 
4650     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4651   }
4652 
4653   nmethod* claim_postponed_nmethod() {
4654     nmethod* claim;
4655     nmethod* next;
4656 
4657     do {
4658       claim = (nmethod*)_postponed_list;
4659       if (claim == NULL) {
4660         return NULL;
4661       }
4662 
4663       next = claim->unloading_next();
4664 
4665     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4666 
4667     return claim;
4668   }
4669 
4670  public:
4671   // Mark that we're done with the first pass of nmethod cleaning.
4672   void barrier_mark(uint worker_id) {
4673     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4674     _num_entered_barrier++;
4675     if (_num_entered_barrier == _num_workers) {
4676       ml.notify_all();
4677     }
4678   }
4679 
4680   // See if we have to wait for the other workers to
4681   // finish their first-pass nmethod cleaning work.
4682   void barrier_wait(uint worker_id) {
4683     if (_num_entered_barrier < _num_workers) {
4684       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4685       while (_num_entered_barrier < _num_workers) {
4686           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4687       }
4688     }
4689   }
4690 
4691   // Cleaning and unloading of nmethods. Some work has to be postponed
4692   // to the second pass, when we know which nmethods survive.
4693   void work_first_pass(uint worker_id) {
4694     // The first nmethods is claimed by the first worker.
4695     if (worker_id == 0 && _first_nmethod != NULL) {
4696       clean_nmethod(_first_nmethod);
4697       _first_nmethod = NULL;
4698     }
4699 
4700     int num_claimed_nmethods;
4701     nmethod* claimed_nmethods[MaxClaimNmethods];
4702 
4703     while (true) {
4704       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4705 
4706       if (num_claimed_nmethods == 0) {
4707         break;
4708       }
4709 
4710       for (int i = 0; i < num_claimed_nmethods; i++) {
4711         clean_nmethod(claimed_nmethods[i]);
4712       }
4713     }
4714   }
4715 
4716   void work_second_pass(uint worker_id) {
4717     nmethod* nm;
4718     // Take care of postponed nmethods.
4719     while ((nm = claim_postponed_nmethod()) != NULL) {
4720       clean_nmethod_postponed(nm);
4721     }
4722   }
4723 };
4724 
4725 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4726 
4727 class G1KlassCleaningTask : public StackObj {
4728   BoolObjectClosure*                      _is_alive;
4729   volatile jint                           _clean_klass_tree_claimed;
4730   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4731 
4732  public:
4733   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4734       _is_alive(is_alive),
4735       _clean_klass_tree_claimed(0),
4736       _klass_iterator() {
4737   }
4738 
4739  private:
4740   bool claim_clean_klass_tree_task() {
4741     if (_clean_klass_tree_claimed) {
4742       return false;
4743     }
4744 
4745     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4746   }
4747 
4748   InstanceKlass* claim_next_klass() {
4749     Klass* klass;
4750     do {
4751       klass =_klass_iterator.next_klass();
4752     } while (klass != NULL && !klass->oop_is_instance());
4753 
4754     return (InstanceKlass*)klass;
4755   }
4756 
4757 public:
4758 
4759   void clean_klass(InstanceKlass* ik) {
4760     ik->clean_implementors_list(_is_alive);
4761     ik->clean_method_data(_is_alive);
4762 
4763     // G1 specific cleanup work that has
4764     // been moved here to be done in parallel.
4765     ik->clean_dependent_nmethods();
4766   }
4767 
4768   void work() {
4769     ResourceMark rm;
4770 
4771     // One worker will clean the subklass/sibling klass tree.
4772     if (claim_clean_klass_tree_task()) {
4773       Klass::clean_subklass_tree(_is_alive);
4774     }
4775 
4776     // All workers will help cleaning the classes,
4777     InstanceKlass* klass;
4778     while ((klass = claim_next_klass()) != NULL) {
4779       clean_klass(klass);
4780     }
4781   }
4782 };
4783 
4784 // To minimize the remark pause times, the tasks below are done in parallel.
4785 class G1ParallelCleaningTask : public AbstractGangTask {
4786 private:
4787   G1StringSymbolTableUnlinkTask _string_symbol_task;
4788   G1CodeCacheUnloadingTask      _code_cache_task;
4789   G1KlassCleaningTask           _klass_cleaning_task;
4790 
4791 public:
4792   // The constructor is run in the VMThread.
4793   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4794       AbstractGangTask("Parallel Cleaning"),
4795       _string_symbol_task(is_alive, process_strings, process_symbols),
4796       _code_cache_task(num_workers, is_alive, unloading_occurred),
4797       _klass_cleaning_task(is_alive) {
4798   }
4799 
4800   // The parallel work done by all worker threads.
4801   void work(uint worker_id) {
4802     // Do first pass of code cache cleaning.
4803     _code_cache_task.work_first_pass(worker_id);
4804 
4805     // Let the threads mark that the first pass is done.
4806     _code_cache_task.barrier_mark(worker_id);
4807 
4808     // Clean the Strings and Symbols.
4809     _string_symbol_task.work(worker_id);
4810 
4811     // Wait for all workers to finish the first code cache cleaning pass.
4812     _code_cache_task.barrier_wait(worker_id);
4813 
4814     // Do the second code cache cleaning work, which realize on
4815     // the liveness information gathered during the first pass.
4816     _code_cache_task.work_second_pass(worker_id);
4817 
4818     // Clean all klasses that were not unloaded.
4819     _klass_cleaning_task.work();
4820   }
4821 };
4822 
4823 
4824 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4825                                         bool process_strings,
4826                                         bool process_symbols,
4827                                         bool class_unloading_occurred) {
4828   uint n_workers = workers()->active_workers();
4829 
4830   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4831                                         n_workers, class_unloading_occurred);
4832   set_par_threads(n_workers);
4833   workers()->run_task(&g1_unlink_task);
4834   set_par_threads(0);
4835 }
4836 
4837 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4838                                                      bool process_strings, bool process_symbols) {
4839   {
4840     uint n_workers = _g1h->workers()->active_workers();
4841     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4842     set_par_threads(n_workers);
4843     workers()->run_task(&g1_unlink_task);
4844     set_par_threads(0);
4845   }
4846 
4847   if (G1StringDedup::is_enabled()) {
4848     G1StringDedup::unlink(is_alive);
4849   }
4850 }
4851 
4852 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4853  private:
4854   DirtyCardQueueSet* _queue;
4855  public:
4856   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4857 
4858   virtual void work(uint worker_id) {
4859     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4860     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4861 
4862     RedirtyLoggedCardTableEntryClosure cl;
4863     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4864 
4865     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4866   }
4867 };
4868 
4869 void G1CollectedHeap::redirty_logged_cards() {
4870   double redirty_logged_cards_start = os::elapsedTime();
4871 
4872   uint n_workers = _g1h->workers()->active_workers();
4873 
4874   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4875   dirty_card_queue_set().reset_for_par_iteration();
4876   set_par_threads(n_workers);
4877   workers()->run_task(&redirty_task);
4878   set_par_threads(0);
4879 
4880   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4881   dcq.merge_bufferlists(&dirty_card_queue_set());
4882   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4883 
4884   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4885 }
4886 
4887 // Weak Reference Processing support
4888 
4889 // An always "is_alive" closure that is used to preserve referents.
4890 // If the object is non-null then it's alive.  Used in the preservation
4891 // of referent objects that are pointed to by reference objects
4892 // discovered by the CM ref processor.
4893 class G1AlwaysAliveClosure: public BoolObjectClosure {
4894   G1CollectedHeap* _g1;
4895 public:
4896   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4897   bool do_object_b(oop p) {
4898     if (p != NULL) {
4899       return true;
4900     }
4901     return false;
4902   }
4903 };
4904 
4905 bool G1STWIsAliveClosure::do_object_b(oop p) {
4906   // An object is reachable if it is outside the collection set,
4907   // or is inside and copied.
4908   return !_g1->obj_in_cs(p) || p->is_forwarded();
4909 }
4910 
4911 // Non Copying Keep Alive closure
4912 class G1KeepAliveClosure: public OopClosure {
4913   G1CollectedHeap* _g1;
4914 public:
4915   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4916   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4917   void do_oop(oop* p) {
4918     oop obj = *p;
4919     assert(obj != NULL, "the caller should have filtered out NULL values");
4920 
4921     const InCSetState cset_state = _g1->in_cset_state(obj);
4922     if (!cset_state.is_in_cset_or_humongous()) {
4923       return;
4924     }
4925     if (cset_state.is_in_cset()) {
4926       assert( obj->is_forwarded(), "invariant" );
4927       *p = obj->forwardee();
4928     } else {
4929       assert(!obj->is_forwarded(), "invariant" );
4930       assert(cset_state.is_humongous(),
4931              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4932       _g1->set_humongous_is_live(obj);
4933     }
4934   }
4935 };
4936 
4937 // Copying Keep Alive closure - can be called from both
4938 // serial and parallel code as long as different worker
4939 // threads utilize different G1ParScanThreadState instances
4940 // and different queues.
4941 
4942 class G1CopyingKeepAliveClosure: public OopClosure {
4943   G1CollectedHeap*         _g1h;
4944   OopClosure*              _copy_non_heap_obj_cl;
4945   G1ParScanThreadState*    _par_scan_state;
4946 
4947 public:
4948   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4949                             OopClosure* non_heap_obj_cl,
4950                             G1ParScanThreadState* pss):
4951     _g1h(g1h),
4952     _copy_non_heap_obj_cl(non_heap_obj_cl),
4953     _par_scan_state(pss)
4954   {}
4955 
4956   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4957   virtual void do_oop(      oop* p) { do_oop_work(p); }
4958 
4959   template <class T> void do_oop_work(T* p) {
4960     oop obj = oopDesc::load_decode_heap_oop(p);
4961 
4962     if (_g1h->is_in_cset_or_humongous(obj)) {
4963       // If the referent object has been forwarded (either copied
4964       // to a new location or to itself in the event of an
4965       // evacuation failure) then we need to update the reference
4966       // field and, if both reference and referent are in the G1
4967       // heap, update the RSet for the referent.
4968       //
4969       // If the referent has not been forwarded then we have to keep
4970       // it alive by policy. Therefore we have copy the referent.
4971       //
4972       // If the reference field is in the G1 heap then we can push
4973       // on the PSS queue. When the queue is drained (after each
4974       // phase of reference processing) the object and it's followers
4975       // will be copied, the reference field set to point to the
4976       // new location, and the RSet updated. Otherwise we need to
4977       // use the the non-heap or metadata closures directly to copy
4978       // the referent object and update the pointer, while avoiding
4979       // updating the RSet.
4980 
4981       if (_g1h->is_in_g1_reserved(p)) {
4982         _par_scan_state->push_on_queue(p);
4983       } else {
4984         assert(!Metaspace::contains((const void*)p),
4985                err_msg("Unexpectedly found a pointer from metadata: "
4986                               PTR_FORMAT, p));
4987         _copy_non_heap_obj_cl->do_oop(p);
4988       }
4989     }
4990   }
4991 };
4992 
4993 // Serial drain queue closure. Called as the 'complete_gc'
4994 // closure for each discovered list in some of the
4995 // reference processing phases.
4996 
4997 class G1STWDrainQueueClosure: public VoidClosure {
4998 protected:
4999   G1CollectedHeap* _g1h;
5000   G1ParScanThreadState* _par_scan_state;
5001 
5002   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5003 
5004 public:
5005   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5006     _g1h(g1h),
5007     _par_scan_state(pss)
5008   { }
5009 
5010   void do_void() {
5011     G1ParScanThreadState* const pss = par_scan_state();
5012     pss->trim_queue();
5013   }
5014 };
5015 
5016 // Parallel Reference Processing closures
5017 
5018 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5019 // processing during G1 evacuation pauses.
5020 
5021 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5022 private:
5023   G1CollectedHeap*   _g1h;
5024   RefToScanQueueSet* _queues;
5025   FlexibleWorkGang*  _workers;
5026   int                _active_workers;
5027 
5028 public:
5029   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5030                         FlexibleWorkGang* workers,
5031                         RefToScanQueueSet *task_queues,
5032                         int n_workers) :
5033     _g1h(g1h),
5034     _queues(task_queues),
5035     _workers(workers),
5036     _active_workers(n_workers)
5037   {
5038     assert(n_workers > 0, "shouldn't call this otherwise");
5039   }
5040 
5041   // Executes the given task using concurrent marking worker threads.
5042   virtual void execute(ProcessTask& task);
5043   virtual void execute(EnqueueTask& task);
5044 };
5045 
5046 // Gang task for possibly parallel reference processing
5047 
5048 class G1STWRefProcTaskProxy: public AbstractGangTask {
5049   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5050   ProcessTask&     _proc_task;
5051   G1CollectedHeap* _g1h;
5052   RefToScanQueueSet *_task_queues;
5053   ParallelTaskTerminator* _terminator;
5054 
5055 public:
5056   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5057                      G1CollectedHeap* g1h,
5058                      RefToScanQueueSet *task_queues,
5059                      ParallelTaskTerminator* terminator) :
5060     AbstractGangTask("Process reference objects in parallel"),
5061     _proc_task(proc_task),
5062     _g1h(g1h),
5063     _task_queues(task_queues),
5064     _terminator(terminator)
5065   {}
5066 
5067   virtual void work(uint worker_id) {
5068     // The reference processing task executed by a single worker.
5069     ResourceMark rm;
5070     HandleMark   hm;
5071 
5072     G1STWIsAliveClosure is_alive(_g1h);
5073 
5074     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5075     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5076 
5077     pss.set_evac_failure_closure(&evac_failure_cl);
5078 
5079     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5080 
5081     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5082 
5083     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5084 
5085     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5086       // We also need to mark copied objects.
5087       copy_non_heap_cl = &copy_mark_non_heap_cl;
5088     }
5089 
5090     // Keep alive closure.
5091     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5092 
5093     // Complete GC closure
5094     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5095 
5096     // Call the reference processing task's work routine.
5097     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5098 
5099     // Note we cannot assert that the refs array is empty here as not all
5100     // of the processing tasks (specifically phase2 - pp2_work) execute
5101     // the complete_gc closure (which ordinarily would drain the queue) so
5102     // the queue may not be empty.
5103   }
5104 };
5105 
5106 // Driver routine for parallel reference processing.
5107 // Creates an instance of the ref processing gang
5108 // task and has the worker threads execute it.
5109 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5110   assert(_workers != NULL, "Need parallel worker threads.");
5111 
5112   ParallelTaskTerminator terminator(_active_workers, _queues);
5113   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5114 
5115   _g1h->set_par_threads(_active_workers);
5116   _workers->run_task(&proc_task_proxy);
5117   _g1h->set_par_threads(0);
5118 }
5119 
5120 // Gang task for parallel reference enqueueing.
5121 
5122 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5123   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5124   EnqueueTask& _enq_task;
5125 
5126 public:
5127   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5128     AbstractGangTask("Enqueue reference objects in parallel"),
5129     _enq_task(enq_task)
5130   { }
5131 
5132   virtual void work(uint worker_id) {
5133     _enq_task.work(worker_id);
5134   }
5135 };
5136 
5137 // Driver routine for parallel reference enqueueing.
5138 // Creates an instance of the ref enqueueing gang
5139 // task and has the worker threads execute it.
5140 
5141 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5142   assert(_workers != NULL, "Need parallel worker threads.");
5143 
5144   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5145 
5146   _g1h->set_par_threads(_active_workers);
5147   _workers->run_task(&enq_task_proxy);
5148   _g1h->set_par_threads(0);
5149 }
5150 
5151 // End of weak reference support closures
5152 
5153 // Abstract task used to preserve (i.e. copy) any referent objects
5154 // that are in the collection set and are pointed to by reference
5155 // objects discovered by the CM ref processor.
5156 
5157 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5158 protected:
5159   G1CollectedHeap* _g1h;
5160   RefToScanQueueSet      *_queues;
5161   ParallelTaskTerminator _terminator;
5162   uint _n_workers;
5163 
5164 public:
5165   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5166     AbstractGangTask("ParPreserveCMReferents"),
5167     _g1h(g1h),
5168     _queues(task_queues),
5169     _terminator(workers, _queues),
5170     _n_workers(workers)
5171   { }
5172 
5173   void work(uint worker_id) {
5174     ResourceMark rm;
5175     HandleMark   hm;
5176 
5177     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5178     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5179 
5180     pss.set_evac_failure_closure(&evac_failure_cl);
5181 
5182     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5183 
5184     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5185 
5186     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5187 
5188     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5189 
5190     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5191       // We also need to mark copied objects.
5192       copy_non_heap_cl = &copy_mark_non_heap_cl;
5193     }
5194 
5195     // Is alive closure
5196     G1AlwaysAliveClosure always_alive(_g1h);
5197 
5198     // Copying keep alive closure. Applied to referent objects that need
5199     // to be copied.
5200     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5201 
5202     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5203 
5204     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5205     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5206 
5207     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5208     // So this must be true - but assert just in case someone decides to
5209     // change the worker ids.
5210     assert(worker_id < limit, "sanity");
5211     assert(!rp->discovery_is_atomic(), "check this code");
5212 
5213     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5214     for (uint idx = worker_id; idx < limit; idx += stride) {
5215       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5216 
5217       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5218       while (iter.has_next()) {
5219         // Since discovery is not atomic for the CM ref processor, we
5220         // can see some null referent objects.
5221         iter.load_ptrs(DEBUG_ONLY(true));
5222         oop ref = iter.obj();
5223 
5224         // This will filter nulls.
5225         if (iter.is_referent_alive()) {
5226           iter.make_referent_alive();
5227         }
5228         iter.move_to_next();
5229       }
5230     }
5231 
5232     // Drain the queue - which may cause stealing
5233     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5234     drain_queue.do_void();
5235     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5236     assert(pss.queue_is_empty(), "should be");
5237   }
5238 };
5239 
5240 // Weak Reference processing during an evacuation pause (part 1).
5241 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5242   double ref_proc_start = os::elapsedTime();
5243 
5244   ReferenceProcessor* rp = _ref_processor_stw;
5245   assert(rp->discovery_enabled(), "should have been enabled");
5246 
5247   // Any reference objects, in the collection set, that were 'discovered'
5248   // by the CM ref processor should have already been copied (either by
5249   // applying the external root copy closure to the discovered lists, or
5250   // by following an RSet entry).
5251   //
5252   // But some of the referents, that are in the collection set, that these
5253   // reference objects point to may not have been copied: the STW ref
5254   // processor would have seen that the reference object had already
5255   // been 'discovered' and would have skipped discovering the reference,
5256   // but would not have treated the reference object as a regular oop.
5257   // As a result the copy closure would not have been applied to the
5258   // referent object.
5259   //
5260   // We need to explicitly copy these referent objects - the references
5261   // will be processed at the end of remarking.
5262   //
5263   // We also need to do this copying before we process the reference
5264   // objects discovered by the STW ref processor in case one of these
5265   // referents points to another object which is also referenced by an
5266   // object discovered by the STW ref processor.
5267 
5268   assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5269 
5270   set_par_threads(no_of_gc_workers);
5271   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5272                                                  no_of_gc_workers,
5273                                                  _task_queues);
5274 
5275   workers()->run_task(&keep_cm_referents);
5276 
5277   set_par_threads(0);
5278 
5279   // Closure to test whether a referent is alive.
5280   G1STWIsAliveClosure is_alive(this);
5281 
5282   // Even when parallel reference processing is enabled, the processing
5283   // of JNI refs is serial and performed serially by the current thread
5284   // rather than by a worker. The following PSS will be used for processing
5285   // JNI refs.
5286 
5287   // Use only a single queue for this PSS.
5288   G1ParScanThreadState            pss(this, 0, NULL);
5289 
5290   // We do not embed a reference processor in the copying/scanning
5291   // closures while we're actually processing the discovered
5292   // reference objects.
5293   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5294 
5295   pss.set_evac_failure_closure(&evac_failure_cl);
5296 
5297   assert(pss.queue_is_empty(), "pre-condition");
5298 
5299   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5300 
5301   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5302 
5303   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5304 
5305   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5306     // We also need to mark copied objects.
5307     copy_non_heap_cl = &copy_mark_non_heap_cl;
5308   }
5309 
5310   // Keep alive closure.
5311   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5312 
5313   // Serial Complete GC closure
5314   G1STWDrainQueueClosure drain_queue(this, &pss);
5315 
5316   // Setup the soft refs policy...
5317   rp->setup_policy(false);
5318 
5319   ReferenceProcessorStats stats;
5320   if (!rp->processing_is_mt()) {
5321     // Serial reference processing...
5322     stats = rp->process_discovered_references(&is_alive,
5323                                               &keep_alive,
5324                                               &drain_queue,
5325                                               NULL,
5326                                               _gc_timer_stw,
5327                                               _gc_tracer_stw->gc_id());
5328   } else {
5329     // Parallel reference processing
5330     assert(rp->num_q() == no_of_gc_workers, "sanity");
5331     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5332 
5333     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5334     stats = rp->process_discovered_references(&is_alive,
5335                                               &keep_alive,
5336                                               &drain_queue,
5337                                               &par_task_executor,
5338                                               _gc_timer_stw,
5339                                               _gc_tracer_stw->gc_id());
5340   }
5341 
5342   _gc_tracer_stw->report_gc_reference_stats(stats);
5343 
5344   // We have completed copying any necessary live referent objects.
5345   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5346 
5347   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5348   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5349 }
5350 
5351 // Weak Reference processing during an evacuation pause (part 2).
5352 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5353   double ref_enq_start = os::elapsedTime();
5354 
5355   ReferenceProcessor* rp = _ref_processor_stw;
5356   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5357 
5358   // Now enqueue any remaining on the discovered lists on to
5359   // the pending list.
5360   if (!rp->processing_is_mt()) {
5361     // Serial reference processing...
5362     rp->enqueue_discovered_references();
5363   } else {
5364     // Parallel reference enqueueing
5365 
5366     assert(no_of_gc_workers == workers()->active_workers(),
5367            "Need to reset active workers");
5368     assert(rp->num_q() == no_of_gc_workers, "sanity");
5369     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5370 
5371     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5372     rp->enqueue_discovered_references(&par_task_executor);
5373   }
5374 
5375   rp->verify_no_references_recorded();
5376   assert(!rp->discovery_enabled(), "should have been disabled");
5377 
5378   // FIXME
5379   // CM's reference processing also cleans up the string and symbol tables.
5380   // Should we do that here also? We could, but it is a serial operation
5381   // and could significantly increase the pause time.
5382 
5383   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5384   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5385 }
5386 
5387 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5388   _expand_heap_after_alloc_failure = true;
5389   _evacuation_failed = false;
5390 
5391   // Should G1EvacuationFailureALot be in effect for this GC?
5392   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5393 
5394   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5395 
5396   // Disable the hot card cache.
5397   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5398   hot_card_cache->reset_hot_cache_claimed_index();
5399   hot_card_cache->set_use_cache(false);
5400 
5401   const uint n_workers = workers()->active_workers();
5402   assert(UseDynamicNumberOfGCThreads ||
5403          n_workers == workers()->total_workers(),
5404          "If not dynamic should be using all the  workers");
5405   set_par_threads(n_workers);
5406 
5407 
5408   init_for_evac_failure(NULL);
5409 
5410   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5411   double start_par_time_sec = os::elapsedTime();
5412   double end_par_time_sec;
5413 
5414   {
5415     G1RootProcessor root_processor(this);
5416     G1ParTask g1_par_task(this, _task_queues, &root_processor);
5417     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5418     if (g1_policy()->during_initial_mark_pause()) {
5419       ClassLoaderDataGraph::clear_claimed_marks();
5420     }
5421 
5422      // The individual threads will set their evac-failure closures.
5423      if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5424      // These tasks use ShareHeap::_process_strong_tasks
5425      assert(UseDynamicNumberOfGCThreads ||
5426             workers()->active_workers() == workers()->total_workers(),
5427             "If not dynamic should be using all the  workers");
5428     workers()->run_task(&g1_par_task);
5429     end_par_time_sec = os::elapsedTime();
5430 
5431     // Closing the inner scope will execute the destructor
5432     // for the G1RootProcessor object. We record the current
5433     // elapsed time before closing the scope so that time
5434     // taken for the destructor is NOT included in the
5435     // reported parallel time.
5436   }
5437 
5438   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5439 
5440   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5441   phase_times->record_par_time(par_time_ms);
5442 
5443   double code_root_fixup_time_ms =
5444         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5445   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5446 
5447   set_par_threads(0);
5448 
5449   // Process any discovered reference objects - we have
5450   // to do this _before_ we retire the GC alloc regions
5451   // as we may have to copy some 'reachable' referent
5452   // objects (and their reachable sub-graphs) that were
5453   // not copied during the pause.
5454   process_discovered_references(n_workers);
5455 
5456   if (G1StringDedup::is_enabled()) {
5457     double fixup_start = os::elapsedTime();
5458 
5459     G1STWIsAliveClosure is_alive(this);
5460     G1KeepAliveClosure keep_alive(this);
5461     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5462 
5463     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5464     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5465   }
5466 
5467   _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5468   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5469 
5470   // Reset and re-enable the hot card cache.
5471   // Note the counts for the cards in the regions in the
5472   // collection set are reset when the collection set is freed.
5473   hot_card_cache->reset_hot_cache();
5474   hot_card_cache->set_use_cache(true);
5475 
5476   purge_code_root_memory();
5477 
5478   finalize_for_evac_failure();
5479 
5480   if (evacuation_failed()) {
5481     remove_self_forwarding_pointers();
5482 
5483     // Reset the G1EvacuationFailureALot counters and flags
5484     // Note: the values are reset only when an actual
5485     // evacuation failure occurs.
5486     NOT_PRODUCT(reset_evacuation_should_fail();)
5487   }
5488 
5489   // Enqueue any remaining references remaining on the STW
5490   // reference processor's discovered lists. We need to do
5491   // this after the card table is cleaned (and verified) as
5492   // the act of enqueueing entries on to the pending list
5493   // will log these updates (and dirty their associated
5494   // cards). We need these updates logged to update any
5495   // RSets.
5496   enqueue_discovered_references(n_workers);
5497 
5498   redirty_logged_cards();
5499   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5500 }
5501 
5502 void G1CollectedHeap::free_region(HeapRegion* hr,
5503                                   FreeRegionList* free_list,
5504                                   bool par,
5505                                   bool locked) {
5506   assert(!hr->is_free(), "the region should not be free");
5507   assert(!hr->is_empty(), "the region should not be empty");
5508   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5509   assert(free_list != NULL, "pre-condition");
5510 
5511   if (G1VerifyBitmaps) {
5512     MemRegion mr(hr->bottom(), hr->end());
5513     concurrent_mark()->clearRangePrevBitmap(mr);
5514   }
5515 
5516   // Clear the card counts for this region.
5517   // Note: we only need to do this if the region is not young
5518   // (since we don't refine cards in young regions).
5519   if (!hr->is_young()) {
5520     _cg1r->hot_card_cache()->reset_card_counts(hr);
5521   }
5522   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5523   free_list->add_ordered(hr);
5524 }
5525 
5526 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5527                                      FreeRegionList* free_list,
5528                                      bool par) {
5529   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5530   assert(free_list != NULL, "pre-condition");
5531 
5532   size_t hr_capacity = hr->capacity();
5533   // We need to read this before we make the region non-humongous,
5534   // otherwise the information will be gone.
5535   uint last_index = hr->last_hc_index();
5536   hr->clear_humongous();
5537   free_region(hr, free_list, par);
5538 
5539   uint i = hr->hrm_index() + 1;
5540   while (i < last_index) {
5541     HeapRegion* curr_hr = region_at(i);
5542     assert(curr_hr->is_continues_humongous(), "invariant");
5543     curr_hr->clear_humongous();
5544     free_region(curr_hr, free_list, par);
5545     i += 1;
5546   }
5547 }
5548 
5549 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5550                                        const HeapRegionSetCount& humongous_regions_removed) {
5551   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5552     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5553     _old_set.bulk_remove(old_regions_removed);
5554     _humongous_set.bulk_remove(humongous_regions_removed);
5555   }
5556 
5557 }
5558 
5559 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5560   assert(list != NULL, "list can't be null");
5561   if (!list->is_empty()) {
5562     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5563     _hrm.insert_list_into_free_list(list);
5564   }
5565 }
5566 
5567 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5568   _allocator->decrease_used(bytes);
5569 }
5570 
5571 class G1ParCleanupCTTask : public AbstractGangTask {
5572   G1SATBCardTableModRefBS* _ct_bs;
5573   G1CollectedHeap* _g1h;
5574   HeapRegion* volatile _su_head;
5575 public:
5576   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5577                      G1CollectedHeap* g1h) :
5578     AbstractGangTask("G1 Par Cleanup CT Task"),
5579     _ct_bs(ct_bs), _g1h(g1h) { }
5580 
5581   void work(uint worker_id) {
5582     HeapRegion* r;
5583     while (r = _g1h->pop_dirty_cards_region()) {
5584       clear_cards(r);
5585     }
5586   }
5587 
5588   void clear_cards(HeapRegion* r) {
5589     // Cards of the survivors should have already been dirtied.
5590     if (!r->is_survivor()) {
5591       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5592     }
5593   }
5594 };
5595 
5596 #ifndef PRODUCT
5597 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5598   G1CollectedHeap* _g1h;
5599   G1SATBCardTableModRefBS* _ct_bs;
5600 public:
5601   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5602     : _g1h(g1h), _ct_bs(ct_bs) { }
5603   virtual bool doHeapRegion(HeapRegion* r) {
5604     if (r->is_survivor()) {
5605       _g1h->verify_dirty_region(r);
5606     } else {
5607       _g1h->verify_not_dirty_region(r);
5608     }
5609     return false;
5610   }
5611 };
5612 
5613 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5614   // All of the region should be clean.
5615   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5616   MemRegion mr(hr->bottom(), hr->end());
5617   ct_bs->verify_not_dirty_region(mr);
5618 }
5619 
5620 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5621   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5622   // dirty allocated blocks as they allocate them. The thread that
5623   // retires each region and replaces it with a new one will do a
5624   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5625   // not dirty that area (one less thing to have to do while holding
5626   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5627   // is dirty.
5628   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5629   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5630   if (hr->is_young()) {
5631     ct_bs->verify_g1_young_region(mr);
5632   } else {
5633     ct_bs->verify_dirty_region(mr);
5634   }
5635 }
5636 
5637 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5638   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5639   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5640     verify_dirty_region(hr);
5641   }
5642 }
5643 
5644 void G1CollectedHeap::verify_dirty_young_regions() {
5645   verify_dirty_young_list(_young_list->first_region());
5646 }
5647 
5648 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5649                                                HeapWord* tams, HeapWord* end) {
5650   guarantee(tams <= end,
5651             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5652   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5653   if (result < end) {
5654     gclog_or_tty->cr();
5655     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5656                            bitmap_name, result);
5657     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5658                            bitmap_name, tams, end);
5659     return false;
5660   }
5661   return true;
5662 }
5663 
5664 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5665   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5666   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5667 
5668   HeapWord* bottom = hr->bottom();
5669   HeapWord* ptams  = hr->prev_top_at_mark_start();
5670   HeapWord* ntams  = hr->next_top_at_mark_start();
5671   HeapWord* end    = hr->end();
5672 
5673   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5674 
5675   bool res_n = true;
5676   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5677   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5678   // if we happen to be in that state.
5679   if (mark_in_progress() || !_cmThread->in_progress()) {
5680     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5681   }
5682   if (!res_p || !res_n) {
5683     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5684                            HR_FORMAT_PARAMS(hr));
5685     gclog_or_tty->print_cr("#### Caller: %s", caller);
5686     return false;
5687   }
5688   return true;
5689 }
5690 
5691 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5692   if (!G1VerifyBitmaps) return;
5693 
5694   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5695 }
5696 
5697 class G1VerifyBitmapClosure : public HeapRegionClosure {
5698 private:
5699   const char* _caller;
5700   G1CollectedHeap* _g1h;
5701   bool _failures;
5702 
5703 public:
5704   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5705     _caller(caller), _g1h(g1h), _failures(false) { }
5706 
5707   bool failures() { return _failures; }
5708 
5709   virtual bool doHeapRegion(HeapRegion* hr) {
5710     if (hr->is_continues_humongous()) return false;
5711 
5712     bool result = _g1h->verify_bitmaps(_caller, hr);
5713     if (!result) {
5714       _failures = true;
5715     }
5716     return false;
5717   }
5718 };
5719 
5720 void G1CollectedHeap::check_bitmaps(const char* caller) {
5721   if (!G1VerifyBitmaps) return;
5722 
5723   G1VerifyBitmapClosure cl(caller, this);
5724   heap_region_iterate(&cl);
5725   guarantee(!cl.failures(), "bitmap verification");
5726 }
5727 
5728 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5729  private:
5730   bool _failures;
5731  public:
5732   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5733 
5734   virtual bool doHeapRegion(HeapRegion* hr) {
5735     uint i = hr->hrm_index();
5736     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5737     if (hr->is_humongous()) {
5738       if (hr->in_collection_set()) {
5739         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5740         _failures = true;
5741         return true;
5742       }
5743       if (cset_state.is_in_cset()) {
5744         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5745         _failures = true;
5746         return true;
5747       }
5748       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5749         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5750         _failures = true;
5751         return true;
5752       }
5753     } else {
5754       if (cset_state.is_humongous()) {
5755         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5756         _failures = true;
5757         return true;
5758       }
5759       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5760         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5761                                hr->in_collection_set(), cset_state.value(), i);
5762         _failures = true;
5763         return true;
5764       }
5765       if (cset_state.is_in_cset()) {
5766         if (hr->is_young() != (cset_state.is_young())) {
5767           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5768                                  hr->is_young(), cset_state.value(), i);
5769           _failures = true;
5770           return true;
5771         }
5772         if (hr->is_old() != (cset_state.is_old())) {
5773           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5774                                  hr->is_old(), cset_state.value(), i);
5775           _failures = true;
5776           return true;
5777         }
5778       }
5779     }
5780     return false;
5781   }
5782 
5783   bool failures() const { return _failures; }
5784 };
5785 
5786 bool G1CollectedHeap::check_cset_fast_test() {
5787   G1CheckCSetFastTableClosure cl;
5788   _hrm.iterate(&cl);
5789   return !cl.failures();
5790 }
5791 #endif // PRODUCT
5792 
5793 void G1CollectedHeap::cleanUpCardTable() {
5794   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5795   double start = os::elapsedTime();
5796 
5797   {
5798     // Iterate over the dirty cards region list.
5799     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5800 
5801     set_par_threads();
5802     workers()->run_task(&cleanup_task);
5803     set_par_threads(0);
5804 #ifndef PRODUCT
5805     if (G1VerifyCTCleanup || VerifyAfterGC) {
5806       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5807       heap_region_iterate(&cleanup_verifier);
5808     }
5809 #endif
5810   }
5811 
5812   double elapsed = os::elapsedTime() - start;
5813   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5814 }
5815 
5816 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5817   size_t pre_used = 0;
5818   FreeRegionList local_free_list("Local List for CSet Freeing");
5819 
5820   double young_time_ms     = 0.0;
5821   double non_young_time_ms = 0.0;
5822 
5823   // Since the collection set is a superset of the the young list,
5824   // all we need to do to clear the young list is clear its
5825   // head and length, and unlink any young regions in the code below
5826   _young_list->clear();
5827 
5828   G1CollectorPolicy* policy = g1_policy();
5829 
5830   double start_sec = os::elapsedTime();
5831   bool non_young = true;
5832 
5833   HeapRegion* cur = cs_head;
5834   int age_bound = -1;
5835   size_t rs_lengths = 0;
5836 
5837   while (cur != NULL) {
5838     assert(!is_on_master_free_list(cur), "sanity");
5839     if (non_young) {
5840       if (cur->is_young()) {
5841         double end_sec = os::elapsedTime();
5842         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5843         non_young_time_ms += elapsed_ms;
5844 
5845         start_sec = os::elapsedTime();
5846         non_young = false;
5847       }
5848     } else {
5849       if (!cur->is_young()) {
5850         double end_sec = os::elapsedTime();
5851         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5852         young_time_ms += elapsed_ms;
5853 
5854         start_sec = os::elapsedTime();
5855         non_young = true;
5856       }
5857     }
5858 
5859     rs_lengths += cur->rem_set()->occupied_locked();
5860 
5861     HeapRegion* next = cur->next_in_collection_set();
5862     assert(cur->in_collection_set(), "bad CS");
5863     cur->set_next_in_collection_set(NULL);
5864     clear_in_cset(cur);
5865 
5866     if (cur->is_young()) {
5867       int index = cur->young_index_in_cset();
5868       assert(index != -1, "invariant");
5869       assert((uint) index < policy->young_cset_region_length(), "invariant");
5870       size_t words_survived = _surviving_young_words[index];
5871       cur->record_surv_words_in_group(words_survived);
5872 
5873       // At this point the we have 'popped' cur from the collection set
5874       // (linked via next_in_collection_set()) but it is still in the
5875       // young list (linked via next_young_region()). Clear the
5876       // _next_young_region field.
5877       cur->set_next_young_region(NULL);
5878     } else {
5879       int index = cur->young_index_in_cset();
5880       assert(index == -1, "invariant");
5881     }
5882 
5883     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5884             (!cur->is_young() && cur->young_index_in_cset() == -1),
5885             "invariant" );
5886 
5887     if (!cur->evacuation_failed()) {
5888       MemRegion used_mr = cur->used_region();
5889 
5890       // And the region is empty.
5891       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5892       pre_used += cur->used();
5893       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5894     } else {
5895       cur->uninstall_surv_rate_group();
5896       if (cur->is_young()) {
5897         cur->set_young_index_in_cset(-1);
5898       }
5899       cur->set_evacuation_failed(false);
5900       // The region is now considered to be old.
5901       cur->set_old();
5902       _old_set.add(cur);
5903       evacuation_info.increment_collectionset_used_after(cur->used());
5904     }
5905     cur = next;
5906   }
5907 
5908   evacuation_info.set_regions_freed(local_free_list.length());
5909   policy->record_max_rs_lengths(rs_lengths);
5910   policy->cset_regions_freed();
5911 
5912   double end_sec = os::elapsedTime();
5913   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5914 
5915   if (non_young) {
5916     non_young_time_ms += elapsed_ms;
5917   } else {
5918     young_time_ms += elapsed_ms;
5919   }
5920 
5921   prepend_to_freelist(&local_free_list);
5922   decrement_summary_bytes(pre_used);
5923   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5924   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5925 }
5926 
5927 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5928  private:
5929   FreeRegionList* _free_region_list;
5930   HeapRegionSet* _proxy_set;
5931   HeapRegionSetCount _humongous_regions_removed;
5932   size_t _freed_bytes;
5933  public:
5934 
5935   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5936     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5937   }
5938 
5939   virtual bool doHeapRegion(HeapRegion* r) {
5940     if (!r->is_starts_humongous()) {
5941       return false;
5942     }
5943 
5944     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5945 
5946     oop obj = (oop)r->bottom();
5947     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5948 
5949     // The following checks whether the humongous object is live are sufficient.
5950     // The main additional check (in addition to having a reference from the roots
5951     // or the young gen) is whether the humongous object has a remembered set entry.
5952     //
5953     // A humongous object cannot be live if there is no remembered set for it
5954     // because:
5955     // - there can be no references from within humongous starts regions referencing
5956     // the object because we never allocate other objects into them.
5957     // (I.e. there are no intra-region references that may be missed by the
5958     // remembered set)
5959     // - as soon there is a remembered set entry to the humongous starts region
5960     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5961     // until the end of a concurrent mark.
5962     //
5963     // It is not required to check whether the object has been found dead by marking
5964     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5965     // all objects allocated during that time are considered live.
5966     // SATB marking is even more conservative than the remembered set.
5967     // So if at this point in the collection there is no remembered set entry,
5968     // nobody has a reference to it.
5969     // At the start of collection we flush all refinement logs, and remembered sets
5970     // are completely up-to-date wrt to references to the humongous object.
5971     //
5972     // Other implementation considerations:
5973     // - never consider object arrays at this time because they would pose
5974     // considerable effort for cleaning up the the remembered sets. This is
5975     // required because stale remembered sets might reference locations that
5976     // are currently allocated into.
5977     uint region_idx = r->hrm_index();
5978     if (g1h->humongous_is_live(region_idx) ||
5979         g1h->humongous_region_is_always_live(region_idx)) {
5980 
5981       if (G1TraceEagerReclaimHumongousObjects) {
5982         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",
5983                                region_idx,
5984                                obj->size()*HeapWordSize,
5985                                r->bottom(),
5986                                r->region_num(),
5987                                r->rem_set()->occupied(),
5988                                r->rem_set()->strong_code_roots_list_length(),
5989                                next_bitmap->isMarked(r->bottom()),
5990                                g1h->humongous_is_live(region_idx),
5991                                obj->is_objArray()
5992                               );
5993       }
5994 
5995       return false;
5996     }
5997 
5998     guarantee(!obj->is_objArray(),
5999               err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6000                       r->bottom()));
6001 
6002     if (G1TraceEagerReclaimHumongousObjects) {
6003       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",
6004                              region_idx,
6005                              obj->size()*HeapWordSize,
6006                              r->bottom(),
6007                              r->region_num(),
6008                              r->rem_set()->occupied(),
6009                              r->rem_set()->strong_code_roots_list_length(),
6010                              next_bitmap->isMarked(r->bottom()),
6011                              g1h->humongous_is_live(region_idx),
6012                              obj->is_objArray()
6013                             );
6014     }
6015     // Need to clear mark bit of the humongous object if already set.
6016     if (next_bitmap->isMarked(r->bottom())) {
6017       next_bitmap->clear(r->bottom());
6018     }
6019     _freed_bytes += r->used();
6020     r->set_containing_set(NULL);
6021     _humongous_regions_removed.increment(1u, r->capacity());
6022     g1h->free_humongous_region(r, _free_region_list, false);
6023 
6024     return false;
6025   }
6026 
6027   HeapRegionSetCount& humongous_free_count() {
6028     return _humongous_regions_removed;
6029   }
6030 
6031   size_t bytes_freed() const {
6032     return _freed_bytes;
6033   }
6034 
6035   size_t humongous_reclaimed() const {
6036     return _humongous_regions_removed.length();
6037   }
6038 };
6039 
6040 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6041   assert_at_safepoint(true);
6042 
6043   if (!G1EagerReclaimHumongousObjects ||
6044       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6045     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6046     return;
6047   }
6048 
6049   double start_time = os::elapsedTime();
6050 
6051   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6052 
6053   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6054   heap_region_iterate(&cl);
6055 
6056   HeapRegionSetCount empty_set;
6057   remove_from_old_sets(empty_set, cl.humongous_free_count());
6058 
6059   G1HRPrinter* hr_printer = _g1h->hr_printer();
6060   if (hr_printer->is_active()) {
6061     FreeRegionListIterator iter(&local_cleanup_list);
6062     while (iter.more_available()) {
6063       HeapRegion* hr = iter.get_next();
6064       hr_printer->cleanup(hr);
6065     }
6066   }
6067 
6068   prepend_to_freelist(&local_cleanup_list);
6069   decrement_summary_bytes(cl.bytes_freed());
6070 
6071   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6072                                                                     cl.humongous_reclaimed());
6073 }
6074 
6075 // This routine is similar to the above but does not record
6076 // any policy statistics or update free lists; we are abandoning
6077 // the current incremental collection set in preparation of a
6078 // full collection. After the full GC we will start to build up
6079 // the incremental collection set again.
6080 // This is only called when we're doing a full collection
6081 // and is immediately followed by the tearing down of the young list.
6082 
6083 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6084   HeapRegion* cur = cs_head;
6085 
6086   while (cur != NULL) {
6087     HeapRegion* next = cur->next_in_collection_set();
6088     assert(cur->in_collection_set(), "bad CS");
6089     cur->set_next_in_collection_set(NULL);
6090     clear_in_cset(cur);
6091     cur->set_young_index_in_cset(-1);
6092     cur = next;
6093   }
6094 }
6095 
6096 void G1CollectedHeap::set_free_regions_coming() {
6097   if (G1ConcRegionFreeingVerbose) {
6098     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6099                            "setting free regions coming");
6100   }
6101 
6102   assert(!free_regions_coming(), "pre-condition");
6103   _free_regions_coming = true;
6104 }
6105 
6106 void G1CollectedHeap::reset_free_regions_coming() {
6107   assert(free_regions_coming(), "pre-condition");
6108 
6109   {
6110     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6111     _free_regions_coming = false;
6112     SecondaryFreeList_lock->notify_all();
6113   }
6114 
6115   if (G1ConcRegionFreeingVerbose) {
6116     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6117                            "reset free regions coming");
6118   }
6119 }
6120 
6121 void G1CollectedHeap::wait_while_free_regions_coming() {
6122   // Most of the time we won't have to wait, so let's do a quick test
6123   // first before we take the lock.
6124   if (!free_regions_coming()) {
6125     return;
6126   }
6127 
6128   if (G1ConcRegionFreeingVerbose) {
6129     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6130                            "waiting for free regions");
6131   }
6132 
6133   {
6134     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6135     while (free_regions_coming()) {
6136       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6137     }
6138   }
6139 
6140   if (G1ConcRegionFreeingVerbose) {
6141     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6142                            "done waiting for free regions");
6143   }
6144 }
6145 
6146 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6147   _young_list->push_region(hr);
6148 }
6149 
6150 class NoYoungRegionsClosure: public HeapRegionClosure {
6151 private:
6152   bool _success;
6153 public:
6154   NoYoungRegionsClosure() : _success(true) { }
6155   bool doHeapRegion(HeapRegion* r) {
6156     if (r->is_young()) {
6157       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6158                              r->bottom(), r->end());
6159       _success = false;
6160     }
6161     return false;
6162   }
6163   bool success() { return _success; }
6164 };
6165 
6166 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6167   bool ret = _young_list->check_list_empty(check_sample);
6168 
6169   if (check_heap) {
6170     NoYoungRegionsClosure closure;
6171     heap_region_iterate(&closure);
6172     ret = ret && closure.success();
6173   }
6174 
6175   return ret;
6176 }
6177 
6178 class TearDownRegionSetsClosure : public HeapRegionClosure {
6179 private:
6180   HeapRegionSet *_old_set;
6181 
6182 public:
6183   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6184 
6185   bool doHeapRegion(HeapRegion* r) {
6186     if (r->is_old()) {
6187       _old_set->remove(r);
6188     } else {
6189       // We ignore free regions, we'll empty the free list afterwards.
6190       // We ignore young regions, we'll empty the young list afterwards.
6191       // We ignore humongous regions, we're not tearing down the
6192       // humongous regions set.
6193       assert(r->is_free() || r->is_young() || r->is_humongous(),
6194              "it cannot be another type");
6195     }
6196     return false;
6197   }
6198 
6199   ~TearDownRegionSetsClosure() {
6200     assert(_old_set->is_empty(), "post-condition");
6201   }
6202 };
6203 
6204 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6205   assert_at_safepoint(true /* should_be_vm_thread */);
6206 
6207   if (!free_list_only) {
6208     TearDownRegionSetsClosure cl(&_old_set);
6209     heap_region_iterate(&cl);
6210 
6211     // Note that emptying the _young_list is postponed and instead done as
6212     // the first step when rebuilding the regions sets again. The reason for
6213     // this is that during a full GC string deduplication needs to know if
6214     // a collected region was young or old when the full GC was initiated.
6215   }
6216   _hrm.remove_all_free_regions();
6217 }
6218 
6219 class RebuildRegionSetsClosure : public HeapRegionClosure {
6220 private:
6221   bool            _free_list_only;
6222   HeapRegionSet*   _old_set;
6223   HeapRegionManager*   _hrm;
6224   size_t          _total_used;
6225 
6226 public:
6227   RebuildRegionSetsClosure(bool free_list_only,
6228                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6229     _free_list_only(free_list_only),
6230     _old_set(old_set), _hrm(hrm), _total_used(0) {
6231     assert(_hrm->num_free_regions() == 0, "pre-condition");
6232     if (!free_list_only) {
6233       assert(_old_set->is_empty(), "pre-condition");
6234     }
6235   }
6236 
6237   bool doHeapRegion(HeapRegion* r) {
6238     if (r->is_continues_humongous()) {
6239       return false;
6240     }
6241 
6242     if (r->is_empty()) {
6243       // Add free regions to the free list
6244       r->set_free();
6245       r->set_allocation_context(AllocationContext::system());
6246       _hrm->insert_into_free_list(r);
6247     } else if (!_free_list_only) {
6248       assert(!r->is_young(), "we should not come across young regions");
6249 
6250       if (r->is_humongous()) {
6251         // We ignore humongous regions, we left the humongous set unchanged
6252       } else {
6253         // Objects that were compacted would have ended up on regions
6254         // that were previously old or free.
6255         assert(r->is_free() || r->is_old(), "invariant");
6256         // We now consider them old, so register as such.
6257         r->set_old();
6258         _old_set->add(r);
6259       }
6260       _total_used += r->used();
6261     }
6262 
6263     return false;
6264   }
6265 
6266   size_t total_used() {
6267     return _total_used;
6268   }
6269 };
6270 
6271 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6272   assert_at_safepoint(true /* should_be_vm_thread */);
6273 
6274   if (!free_list_only) {
6275     _young_list->empty_list();
6276   }
6277 
6278   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6279   heap_region_iterate(&cl);
6280 
6281   if (!free_list_only) {
6282     _allocator->set_used(cl.total_used());
6283   }
6284   assert(_allocator->used_unlocked() == recalculate_used(),
6285          err_msg("inconsistent _allocator->used_unlocked(), "
6286                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6287                  _allocator->used_unlocked(), recalculate_used()));
6288 }
6289 
6290 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6291   _refine_cte_cl->set_concurrent(concurrent);
6292 }
6293 
6294 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6295   HeapRegion* hr = heap_region_containing(p);
6296   return hr->is_in(p);
6297 }
6298 
6299 // Methods for the mutator alloc region
6300 
6301 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6302                                                       bool force) {
6303   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6304   assert(!force || g1_policy()->can_expand_young_list(),
6305          "if force is true we should be able to expand the young list");
6306   bool young_list_full = g1_policy()->is_young_list_full();
6307   if (force || !young_list_full) {
6308     HeapRegion* new_alloc_region = new_region(word_size,
6309                                               false /* is_old */,
6310                                               false /* do_expand */);
6311     if (new_alloc_region != NULL) {
6312       set_region_short_lived_locked(new_alloc_region);
6313       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6314       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6315       return new_alloc_region;
6316     }
6317   }
6318   return NULL;
6319 }
6320 
6321 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6322                                                   size_t allocated_bytes) {
6323   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6324   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6325 
6326   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6327   _allocator->increase_used(allocated_bytes);
6328   _hr_printer.retire(alloc_region);
6329   // We update the eden sizes here, when the region is retired,
6330   // instead of when it's allocated, since this is the point that its
6331   // used space has been recored in _summary_bytes_used.
6332   g1mm()->update_eden_size();
6333 }
6334 
6335 void G1CollectedHeap::set_par_threads() {
6336   // Don't change the number of workers.  Use the value previously set
6337   // in the workgroup.
6338   uint n_workers = workers()->active_workers();
6339   assert(UseDynamicNumberOfGCThreads ||
6340            n_workers == workers()->total_workers(),
6341       "Otherwise should be using the total number of workers");
6342   if (n_workers == 0) {
6343     assert(false, "Should have been set in prior evacuation pause.");
6344     n_workers = ParallelGCThreads;
6345     workers()->set_active_workers(n_workers);
6346   }
6347   set_par_threads(n_workers);
6348 }
6349 
6350 // Methods for the GC alloc regions
6351 
6352 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6353                                                  uint count,
6354                                                  InCSetState dest) {
6355   assert(FreeList_lock->owned_by_self(), "pre-condition");
6356 
6357   if (count < g1_policy()->max_regions(dest)) {
6358     const bool is_survivor = (dest.is_young());
6359     HeapRegion* new_alloc_region = new_region(word_size,
6360                                               !is_survivor,
6361                                               true /* do_expand */);
6362     if (new_alloc_region != NULL) {
6363       // We really only need to do this for old regions given that we
6364       // should never scan survivors. But it doesn't hurt to do it
6365       // for survivors too.
6366       new_alloc_region->record_timestamp();
6367       if (is_survivor) {
6368         new_alloc_region->set_survivor();
6369         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6370         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6371       } else {
6372         new_alloc_region->set_old();
6373         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6374         check_bitmaps("Old Region Allocation", new_alloc_region);
6375       }
6376       bool during_im = g1_policy()->during_initial_mark_pause();
6377       new_alloc_region->note_start_of_copying(during_im);
6378       return new_alloc_region;
6379     }
6380   }
6381   return NULL;
6382 }
6383 
6384 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6385                                              size_t allocated_bytes,
6386                                              InCSetState dest) {
6387   bool during_im = g1_policy()->during_initial_mark_pause();
6388   alloc_region->note_end_of_copying(during_im);
6389   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6390   if (dest.is_young()) {
6391     young_list()->add_survivor_region(alloc_region);
6392   } else {
6393     _old_set.add(alloc_region);
6394   }
6395   _hr_printer.retire(alloc_region);
6396 }
6397 
6398 // Heap region set verification
6399 
6400 class VerifyRegionListsClosure : public HeapRegionClosure {
6401 private:
6402   HeapRegionSet*   _old_set;
6403   HeapRegionSet*   _humongous_set;
6404   HeapRegionManager*   _hrm;
6405 
6406 public:
6407   HeapRegionSetCount _old_count;
6408   HeapRegionSetCount _humongous_count;
6409   HeapRegionSetCount _free_count;
6410 
6411   VerifyRegionListsClosure(HeapRegionSet* old_set,
6412                            HeapRegionSet* humongous_set,
6413                            HeapRegionManager* hrm) :
6414     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6415     _old_count(), _humongous_count(), _free_count(){ }
6416 
6417   bool doHeapRegion(HeapRegion* hr) {
6418     if (hr->is_continues_humongous()) {
6419       return false;
6420     }
6421 
6422     if (hr->is_young()) {
6423       // TODO
6424     } else if (hr->is_starts_humongous()) {
6425       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6426       _humongous_count.increment(1u, hr->capacity());
6427     } else if (hr->is_empty()) {
6428       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6429       _free_count.increment(1u, hr->capacity());
6430     } else if (hr->is_old()) {
6431       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6432       _old_count.increment(1u, hr->capacity());
6433     } else {
6434       ShouldNotReachHere();
6435     }
6436     return false;
6437   }
6438 
6439   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6440     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6441     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6442         old_set->total_capacity_bytes(), _old_count.capacity()));
6443 
6444     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6445     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6446         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6447 
6448     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()));
6449     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6450         free_list->total_capacity_bytes(), _free_count.capacity()));
6451   }
6452 };
6453 
6454 void G1CollectedHeap::verify_region_sets() {
6455   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6456 
6457   // First, check the explicit lists.
6458   _hrm.verify();
6459   {
6460     // Given that a concurrent operation might be adding regions to
6461     // the secondary free list we have to take the lock before
6462     // verifying it.
6463     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6464     _secondary_free_list.verify_list();
6465   }
6466 
6467   // If a concurrent region freeing operation is in progress it will
6468   // be difficult to correctly attributed any free regions we come
6469   // across to the correct free list given that they might belong to
6470   // one of several (free_list, secondary_free_list, any local lists,
6471   // etc.). So, if that's the case we will skip the rest of the
6472   // verification operation. Alternatively, waiting for the concurrent
6473   // operation to complete will have a non-trivial effect on the GC's
6474   // operation (no concurrent operation will last longer than the
6475   // interval between two calls to verification) and it might hide
6476   // any issues that we would like to catch during testing.
6477   if (free_regions_coming()) {
6478     return;
6479   }
6480 
6481   // Make sure we append the secondary_free_list on the free_list so
6482   // that all free regions we will come across can be safely
6483   // attributed to the free_list.
6484   append_secondary_free_list_if_not_empty_with_lock();
6485 
6486   // Finally, make sure that the region accounting in the lists is
6487   // consistent with what we see in the heap.
6488 
6489   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6490   heap_region_iterate(&cl);
6491   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6492 }
6493 
6494 // Optimized nmethod scanning
6495 
6496 class RegisterNMethodOopClosure: public OopClosure {
6497   G1CollectedHeap* _g1h;
6498   nmethod* _nm;
6499 
6500   template <class T> void do_oop_work(T* p) {
6501     T heap_oop = oopDesc::load_heap_oop(p);
6502     if (!oopDesc::is_null(heap_oop)) {
6503       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6504       HeapRegion* hr = _g1h->heap_region_containing(obj);
6505       assert(!hr->is_continues_humongous(),
6506              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6507                      " starting at "HR_FORMAT,
6508                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6509 
6510       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6511       hr->add_strong_code_root_locked(_nm);
6512     }
6513   }
6514 
6515 public:
6516   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6517     _g1h(g1h), _nm(nm) {}
6518 
6519   void do_oop(oop* p)       { do_oop_work(p); }
6520   void do_oop(narrowOop* p) { do_oop_work(p); }
6521 };
6522 
6523 class UnregisterNMethodOopClosure: public OopClosure {
6524   G1CollectedHeap* _g1h;
6525   nmethod* _nm;
6526 
6527   template <class T> void do_oop_work(T* p) {
6528     T heap_oop = oopDesc::load_heap_oop(p);
6529     if (!oopDesc::is_null(heap_oop)) {
6530       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6531       HeapRegion* hr = _g1h->heap_region_containing(obj);
6532       assert(!hr->is_continues_humongous(),
6533              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6534                      " starting at "HR_FORMAT,
6535                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6536 
6537       hr->remove_strong_code_root(_nm);
6538     }
6539   }
6540 
6541 public:
6542   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6543     _g1h(g1h), _nm(nm) {}
6544 
6545   void do_oop(oop* p)       { do_oop_work(p); }
6546   void do_oop(narrowOop* p) { do_oop_work(p); }
6547 };
6548 
6549 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6550   CollectedHeap::register_nmethod(nm);
6551 
6552   guarantee(nm != NULL, "sanity");
6553   RegisterNMethodOopClosure reg_cl(this, nm);
6554   nm->oops_do(&reg_cl);
6555 }
6556 
6557 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6558   CollectedHeap::unregister_nmethod(nm);
6559 
6560   guarantee(nm != NULL, "sanity");
6561   UnregisterNMethodOopClosure reg_cl(this, nm);
6562   nm->oops_do(&reg_cl, true);
6563 }
6564 
6565 void G1CollectedHeap::purge_code_root_memory() {
6566   double purge_start = os::elapsedTime();
6567   G1CodeRootSet::purge();
6568   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6569   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6570 }
6571 
6572 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6573   G1CollectedHeap* _g1h;
6574 
6575 public:
6576   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6577     _g1h(g1h) {}
6578 
6579   void do_code_blob(CodeBlob* cb) {
6580     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6581     if (nm == NULL) {
6582       return;
6583     }
6584 
6585     if (ScavengeRootsInCode) {
6586       _g1h->register_nmethod(nm);
6587     }
6588   }
6589 };
6590 
6591 void G1CollectedHeap::rebuild_strong_code_roots() {
6592   RebuildStrongCodeRootClosure blob_cl(this);
6593   CodeCache::blobs_do(&blob_cl);
6594 }