1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #if !defined(__clang_major__) && defined(__GNUC__)
  26 // FIXME, formats have issues.  Disable this macro definition, compile, and study warnings for more information.
  27 #define ATTRIBUTE_PRINTF(x,y)
  28 #endif
  29 
  30 #include "precompiled.hpp"
  31 #include "classfile/metadataOnStackMark.hpp"
  32 #include "classfile/stringTable.hpp"
  33 #include "code/codeCache.hpp"
  34 #include "code/icBuffer.hpp"
  35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  43 #include "gc_implementation/g1/g1EvacFailure.hpp"
  44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  45 #include "gc_implementation/g1/g1Log.hpp"
  46 #include "gc_implementation/g1/g1MarkSweep.hpp"
  47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
  49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
  50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  51 #include "gc_implementation/g1/g1RootProcessor.hpp"
  52 #include "gc_implementation/g1/g1StringDedup.hpp"
  53 #include "gc_implementation/g1/g1YCTypes.hpp"
  54 #include "gc_implementation/g1/heapRegion.inline.hpp"
  55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
  57 #include "gc_implementation/g1/vm_operations_g1.hpp"
  58 #include "gc_implementation/shared/gcHeapSummary.hpp"
  59 #include "gc_implementation/shared/gcTimer.hpp"
  60 #include "gc_implementation/shared/gcTrace.hpp"
  61 #include "gc_implementation/shared/gcTraceTime.hpp"
  62 #include "gc_implementation/shared/isGCActiveMark.hpp"
  63 #include "memory/allocation.hpp"
  64 #include "memory/gcLocker.inline.hpp"
  65 #include "memory/generationSpec.hpp"
  66 #include "memory/iterator.hpp"
  67 #include "memory/referenceProcessor.hpp"
  68 #include "oops/oop.inline.hpp"
  69 #include "runtime/atomic.inline.hpp"
  70 #include "runtime/orderAccess.inline.hpp"
  71 #include "runtime/vmThread.hpp"
  72 #include "utilities/globalDefinitions.hpp"
  73 
  74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  75 
  76 // turn it on so that the contents of the young list (scan-only /
  77 // to-be-collected) are printed at "strategic" points before / during
  78 // / after the collection --- this is useful for debugging
  79 #define YOUNG_LIST_VERBOSE 0
  80 // CURRENT STATUS
  81 // This file is under construction.  Search for "FIXME".
  82 
  83 // INVARIANTS/NOTES
  84 //
  85 // All allocation activity covered by the G1CollectedHeap interface is
  86 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  87 // and allocate_new_tlab, which are the "entry" points to the
  88 // allocation code from the rest of the JVM.  (Note that this does not
  89 // apply to TLAB allocation, which is not part of this interface: it
  90 // is done by clients of this interface.)
  91 
  92 // Local to this file.
  93 
  94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  95   bool _concurrent;
  96 public:
  97   RefineCardTableEntryClosure() : _concurrent(true) { }
  98 
  99   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 100     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 101     // This path is executed by the concurrent refine or mutator threads,
 102     // concurrently, and so we do not care if card_ptr contains references
 103     // that point into the collection set.
 104     assert(!oops_into_cset, "should be");
 105 
 106     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 107       // Caller will actually yield.
 108       return false;
 109     }
 110     // Otherwise, we finished successfully; return true.
 111     return true;
 112   }
 113 
 114   void set_concurrent(bool b) { _concurrent = b; }
 115 };
 116 
 117 
 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 119  private:
 120   size_t _num_processed;
 121 
 122  public:
 123   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 124 
 125   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 126     *card_ptr = CardTableModRefBS::dirty_card_val();
 127     _num_processed++;
 128     return true;
 129   }
 130 
 131   size_t num_processed() const { return _num_processed; }
 132 };
 133 
 134 YoungList::YoungList(G1CollectedHeap* g1h) :
 135     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 136     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 137   guarantee(check_list_empty(false), "just making sure...");
 138 }
 139 
 140 void YoungList::push_region(HeapRegion *hr) {
 141   assert(!hr->is_young(), "should not already be young");
 142   assert(hr->get_next_young_region() == NULL, "cause it should!");
 143 
 144   hr->set_next_young_region(_head);
 145   _head = hr;
 146 
 147   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 148   ++_length;
 149 }
 150 
 151 void YoungList::add_survivor_region(HeapRegion* hr) {
 152   assert(hr->is_survivor(), "should be flagged as survivor region");
 153   assert(hr->get_next_young_region() == NULL, "cause it should!");
 154 
 155   hr->set_next_young_region(_survivor_head);
 156   if (_survivor_head == NULL) {
 157     _survivor_tail = hr;
 158   }
 159   _survivor_head = hr;
 160   ++_survivor_length;
 161 }
 162 
 163 void YoungList::empty_list(HeapRegion* list) {
 164   while (list != NULL) {
 165     HeapRegion* next = list->get_next_young_region();
 166     list->set_next_young_region(NULL);
 167     list->uninstall_surv_rate_group();
 168     // This is called before a Full GC and all the non-empty /
 169     // non-humongous regions at the end of the Full GC will end up as
 170     // old anyway.
 171     list->set_old();
 172     list = next;
 173   }
 174 }
 175 
 176 void YoungList::empty_list() {
 177   assert(check_list_well_formed(), "young list should be well formed");
 178 
 179   empty_list(_head);
 180   _head = NULL;
 181   _length = 0;
 182 
 183   empty_list(_survivor_head);
 184   _survivor_head = NULL;
 185   _survivor_tail = NULL;
 186   _survivor_length = 0;
 187 
 188   _last_sampled_rs_lengths = 0;
 189 
 190   assert(check_list_empty(false), "just making sure...");
 191 }
 192 
 193 bool YoungList::check_list_well_formed() {
 194   bool ret = true;
 195 
 196   uint length = 0;
 197   HeapRegion* curr = _head;
 198   HeapRegion* last = NULL;
 199   while (curr != NULL) {
 200     if (!curr->is_young()) {
 201       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 202                              "incorrectly tagged (y: %d, surv: %d)",
 203                              curr->bottom(), curr->end(),
 204                              curr->is_young(), curr->is_survivor());
 205       ret = false;
 206     }
 207     ++length;
 208     last = curr;
 209     curr = curr->get_next_young_region();
 210   }
 211   ret = ret && (length == _length);
 212 
 213   if (!ret) {
 214     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 215     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 216                            length, _length);
 217   }
 218 
 219   return ret;
 220 }
 221 
 222 bool YoungList::check_list_empty(bool check_sample) {
 223   bool ret = true;
 224 
 225   if (_length != 0) {
 226     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 227                   _length);
 228     ret = false;
 229   }
 230   if (check_sample && _last_sampled_rs_lengths != 0) {
 231     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 232     ret = false;
 233   }
 234   if (_head != NULL) {
 235     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 236     ret = false;
 237   }
 238   if (!ret) {
 239     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 240   }
 241 
 242   return ret;
 243 }
 244 
 245 void
 246 YoungList::rs_length_sampling_init() {
 247   _sampled_rs_lengths = 0;
 248   _curr               = _head;
 249 }
 250 
 251 bool
 252 YoungList::rs_length_sampling_more() {
 253   return _curr != NULL;
 254 }
 255 
 256 void
 257 YoungList::rs_length_sampling_next() {
 258   assert( _curr != NULL, "invariant" );
 259   size_t rs_length = _curr->rem_set()->occupied();
 260 
 261   _sampled_rs_lengths += rs_length;
 262 
 263   // The current region may not yet have been added to the
 264   // incremental collection set (it gets added when it is
 265   // retired as the current allocation region).
 266   if (_curr->in_collection_set()) {
 267     // Update the collection set policy information for this region
 268     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 269   }
 270 
 271   _curr = _curr->get_next_young_region();
 272   if (_curr == NULL) {
 273     _last_sampled_rs_lengths = _sampled_rs_lengths;
 274     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 275   }
 276 }
 277 
 278 void
 279 YoungList::reset_auxilary_lists() {
 280   guarantee( is_empty(), "young list should be empty" );
 281   assert(check_list_well_formed(), "young list should be well formed");
 282 
 283   // Add survivor regions to SurvRateGroup.
 284   _g1h->g1_policy()->note_start_adding_survivor_regions();
 285   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 286 
 287   int young_index_in_cset = 0;
 288   for (HeapRegion* curr = _survivor_head;
 289        curr != NULL;
 290        curr = curr->get_next_young_region()) {
 291     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 292 
 293     // The region is a non-empty survivor so let's add it to
 294     // the incremental collection set for the next evacuation
 295     // pause.
 296     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 297     young_index_in_cset += 1;
 298   }
 299   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 300   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 301 
 302   _head   = _survivor_head;
 303   _length = _survivor_length;
 304   if (_survivor_head != NULL) {
 305     assert(_survivor_tail != NULL, "cause it shouldn't be");
 306     assert(_survivor_length > 0, "invariant");
 307     _survivor_tail->set_next_young_region(NULL);
 308   }
 309 
 310   // Don't clear the survivor list handles until the start of
 311   // the next evacuation pause - we need it in order to re-tag
 312   // the survivor regions from this evacuation pause as 'young'
 313   // at the start of the next.
 314 
 315   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 316 
 317   assert(check_list_well_formed(), "young list should be well formed");
 318 }
 319 
 320 void YoungList::print() {
 321   HeapRegion* lists[] = {_head,   _survivor_head};
 322   const char* names[] = {"YOUNG", "SURVIVOR"};
 323 
 324   for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
 325     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 326     HeapRegion *curr = lists[list];
 327     if (curr == NULL)
 328       gclog_or_tty->print_cr("  empty");
 329     while (curr != NULL) {
 330       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
 331                              HR_FORMAT_PARAMS(curr),
 332                              curr->prev_top_at_mark_start(),
 333                              curr->next_top_at_mark_start(),
 334                              curr->age_in_surv_rate_group_cond());
 335       curr = curr->get_next_young_region();
 336     }
 337   }
 338 
 339   gclog_or_tty->cr();
 340 }
 341 
 342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 343   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 344 }
 345 
 346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 347   // The from card cache is not the memory that is actually committed. So we cannot
 348   // take advantage of the zero_filled parameter.
 349   reset_from_card_cache(start_idx, num_regions);
 350 }
 351 
 352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 353 {
 354   // Claim the right to put the region on the dirty cards region list
 355   // by installing a self pointer.
 356   HeapRegion* next = hr->get_next_dirty_cards_region();
 357   if (next == NULL) {
 358     HeapRegion* res = (HeapRegion*)
 359       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 360                           NULL);
 361     if (res == NULL) {
 362       HeapRegion* head;
 363       do {
 364         // Put the region to the dirty cards region list.
 365         head = _dirty_cards_region_list;
 366         next = (HeapRegion*)
 367           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 368         if (next == head) {
 369           assert(hr->get_next_dirty_cards_region() == hr,
 370                  "hr->get_next_dirty_cards_region() != hr");
 371           if (next == NULL) {
 372             // The last region in the list points to itself.
 373             hr->set_next_dirty_cards_region(hr);
 374           } else {
 375             hr->set_next_dirty_cards_region(next);
 376           }
 377         }
 378       } while (next != head);
 379     }
 380   }
 381 }
 382 
 383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 384 {
 385   HeapRegion* head;
 386   HeapRegion* hr;
 387   do {
 388     head = _dirty_cards_region_list;
 389     if (head == NULL) {
 390       return NULL;
 391     }
 392     HeapRegion* new_head = head->get_next_dirty_cards_region();
 393     if (head == new_head) {
 394       // The last region.
 395       new_head = NULL;
 396     }
 397     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 398                                           head);
 399   } while (hr != head);
 400   assert(hr != NULL, "invariant");
 401   hr->set_next_dirty_cards_region(NULL);
 402   return hr;
 403 }
 404 
 405 // Returns true if the reference points to an object that
 406 // can move in an incremental collection.
 407 bool G1CollectedHeap::is_scavengable(const void* p) {
 408   HeapRegion* hr = heap_region_containing(p);
 409   return !hr->is_humongous();
 410 }
 411 
 412 // Private class members.
 413 
 414 G1CollectedHeap* G1CollectedHeap::_g1h;
 415 
 416 // Private methods.
 417 
 418 HeapRegion*
 419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 420   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 421   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 422     if (!_secondary_free_list.is_empty()) {
 423       if (G1ConcRegionFreeingVerbose) {
 424         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 425                                "secondary_free_list has %u entries",
 426                                _secondary_free_list.length());
 427       }
 428       // It looks as if there are free regions available on the
 429       // secondary_free_list. Let's move them to the free_list and try
 430       // again to allocate from it.
 431       append_secondary_free_list();
 432 
 433       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 434              "empty we should have moved at least one entry to the free_list");
 435       HeapRegion* res = _hrm.allocate_free_region(is_old);
 436       if (G1ConcRegionFreeingVerbose) {
 437         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 438                                "allocated "HR_FORMAT" from secondary_free_list",
 439                                HR_FORMAT_PARAMS(res));
 440       }
 441       return res;
 442     }
 443 
 444     // Wait here until we get notified either when (a) there are no
 445     // more free regions coming or (b) some regions have been moved on
 446     // the secondary_free_list.
 447     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 448   }
 449 
 450   if (G1ConcRegionFreeingVerbose) {
 451     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 452                            "could not allocate from secondary_free_list");
 453   }
 454   return NULL;
 455 }
 456 
 457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 458   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 459          "the only time we use this to allocate a humongous region is "
 460          "when we are allocating a single humongous region");
 461 
 462   HeapRegion* res;
 463   if (G1StressConcRegionFreeing) {
 464     if (!_secondary_free_list.is_empty()) {
 465       if (G1ConcRegionFreeingVerbose) {
 466         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 467                                "forced to look at the secondary_free_list");
 468       }
 469       res = new_region_try_secondary_free_list(is_old);
 470       if (res != NULL) {
 471         return res;
 472       }
 473     }
 474   }
 475 
 476   res = _hrm.allocate_free_region(is_old);
 477 
 478   if (res == NULL) {
 479     if (G1ConcRegionFreeingVerbose) {
 480       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 481                              "res == NULL, trying the secondary_free_list");
 482     }
 483     res = new_region_try_secondary_free_list(is_old);
 484   }
 485   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 486     // Currently, only attempts to allocate GC alloc regions set
 487     // do_expand to true. So, we should only reach here during a
 488     // safepoint. If this assumption changes we might have to
 489     // reconsider the use of _expand_heap_after_alloc_failure.
 490     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 491 
 492     ergo_verbose1(ErgoHeapSizing,
 493                   "attempt heap expansion",
 494                   ergo_format_reason("region allocation request failed")
 495                   ergo_format_byte("allocation request"),
 496                   word_size * HeapWordSize);
 497     if (expand(word_size * HeapWordSize)) {
 498       // Given that expand() succeeded in expanding the heap, and we
 499       // always expand the heap by an amount aligned to the heap
 500       // region size, the free list should in theory not be empty.
 501       // In either case allocate_free_region() will check for NULL.
 502       res = _hrm.allocate_free_region(is_old);
 503     } else {
 504       _expand_heap_after_alloc_failure = false;
 505     }
 506   }
 507   return res;
 508 }
 509 
 510 HeapWord*
 511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 512                                                            uint num_regions,
 513                                                            size_t word_size,
 514                                                            AllocationContext_t context) {
 515   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 516   assert(is_humongous(word_size), "word_size should be humongous");
 517   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 518 
 519   // Index of last region in the series + 1.
 520   uint last = first + num_regions;
 521 
 522   // We need to initialize the region(s) we just discovered. This is
 523   // a bit tricky given that it can happen concurrently with
 524   // refinement threads refining cards on these regions and
 525   // potentially wanting to refine the BOT as they are scanning
 526   // those cards (this can happen shortly after a cleanup; see CR
 527   // 6991377). So we have to set up the region(s) carefully and in
 528   // a specific order.
 529 
 530   // The word size sum of all the regions we will allocate.
 531   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 532   assert(word_size <= word_size_sum, "sanity");
 533 
 534   // This will be the "starts humongous" region.
 535   HeapRegion* first_hr = region_at(first);
 536   // The header of the new object will be placed at the bottom of
 537   // the first region.
 538   HeapWord* new_obj = first_hr->bottom();
 539   // This will be the new end of the first region in the series that
 540   // should also match the end of the last region in the series.
 541   HeapWord* new_end = new_obj + word_size_sum;
 542   // This will be the new top of the first region that will reflect
 543   // this allocation.
 544   HeapWord* new_top = new_obj + word_size;
 545 
 546   // First, we need to zero the header of the space that we will be
 547   // allocating. When we update top further down, some refinement
 548   // threads might try to scan the region. By zeroing the header we
 549   // ensure that any thread that will try to scan the region will
 550   // come across the zero klass word and bail out.
 551   //
 552   // NOTE: It would not have been correct to have used
 553   // CollectedHeap::fill_with_object() and make the space look like
 554   // an int array. The thread that is doing the allocation will
 555   // later update the object header to a potentially different array
 556   // type and, for a very short period of time, the klass and length
 557   // fields will be inconsistent. This could cause a refinement
 558   // thread to calculate the object size incorrectly.
 559   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 560 
 561   // We will set up the first region as "starts humongous". This
 562   // will also update the BOT covering all the regions to reflect
 563   // that there is a single object that starts at the bottom of the
 564   // first region.
 565   first_hr->set_starts_humongous(new_top, new_end);
 566   first_hr->set_allocation_context(context);
 567   // Then, if there are any, we will set up the "continues
 568   // humongous" regions.
 569   HeapRegion* hr = NULL;
 570   for (uint i = first + 1; i < last; ++i) {
 571     hr = region_at(i);
 572     hr->set_continues_humongous(first_hr);
 573     hr->set_allocation_context(context);
 574   }
 575   // If we have "continues humongous" regions (hr != NULL), then the
 576   // end of the last one should match new_end.
 577   assert(hr == NULL || hr->end() == new_end, "sanity");
 578 
 579   // Up to this point no concurrent thread would have been able to
 580   // do any scanning on any region in this series. All the top
 581   // fields still point to bottom, so the intersection between
 582   // [bottom,top] and [card_start,card_end] will be empty. Before we
 583   // update the top fields, we'll do a storestore to make sure that
 584   // no thread sees the update to top before the zeroing of the
 585   // object header and the BOT initialization.
 586   OrderAccess::storestore();
 587 
 588   // Now that the BOT and the object header have been initialized,
 589   // we can update top of the "starts humongous" region.
 590   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 591          "new_top should be in this region");
 592   first_hr->set_top(new_top);
 593   if (_hr_printer.is_active()) {
 594     HeapWord* bottom = first_hr->bottom();
 595     HeapWord* end = first_hr->orig_end();
 596     if ((first + 1) == last) {
 597       // the series has a single humongous region
 598       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 599     } else {
 600       // the series has more than one humongous regions
 601       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 602     }
 603   }
 604 
 605   // Now, we will update the top fields of the "continues humongous"
 606   // regions. The reason we need to do this is that, otherwise,
 607   // these regions would look empty and this will confuse parts of
 608   // G1. For example, the code that looks for a consecutive number
 609   // of empty regions will consider them empty and try to
 610   // re-allocate them. We can extend is_empty() to also include
 611   // !is_continues_humongous(), but it is easier to just update the top
 612   // fields here. The way we set top for all regions (i.e., top ==
 613   // end for all regions but the last one, top == new_top for the
 614   // last one) is actually used when we will free up the humongous
 615   // region in free_humongous_region().
 616   hr = NULL;
 617   for (uint i = first + 1; i < last; ++i) {
 618     hr = region_at(i);
 619     if ((i + 1) == last) {
 620       // last continues humongous region
 621       assert(hr->bottom() < new_top && new_top <= hr->end(),
 622              "new_top should fall on this region");
 623       hr->set_top(new_top);
 624       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 625     } else {
 626       // not last one
 627       assert(new_top > hr->end(), "new_top should be above this region");
 628       hr->set_top(hr->end());
 629       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 630     }
 631   }
 632   // If we have continues humongous regions (hr != NULL), then the
 633   // end of the last one should match new_end and its top should
 634   // match new_top.
 635   assert(hr == NULL ||
 636          (hr->end() == new_end && hr->top() == new_top), "sanity");
 637   check_bitmaps("Humongous Region Allocation", first_hr);
 638 
 639   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 640   _allocator->increase_used(first_hr->used());
 641   _humongous_set.add(first_hr);
 642 
 643   return new_obj;
 644 }
 645 
 646 // If could fit into free regions w/o expansion, try.
 647 // Otherwise, if can expand, do so.
 648 // Otherwise, if using ex regions might help, try with ex given back.
 649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 650   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 651 
 652   verify_region_sets_optional();
 653 
 654   uint first = G1_NO_HRM_INDEX;
 655   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 656 
 657   if (obj_regions == 1) {
 658     // Only one region to allocate, try to use a fast path by directly allocating
 659     // from the free lists. Do not try to expand here, we will potentially do that
 660     // later.
 661     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 662     if (hr != NULL) {
 663       first = hr->hrm_index();
 664     }
 665   } else {
 666     // We can't allocate humongous regions spanning more than one region while
 667     // cleanupComplete() is running, since some of the regions we find to be
 668     // empty might not yet be added to the free list. It is not straightforward
 669     // to know in which list they are on so that we can remove them. We only
 670     // need to do this if we need to allocate more than one region to satisfy the
 671     // current humongous allocation request. If we are only allocating one region
 672     // we use the one-region region allocation code (see above), that already
 673     // potentially waits for regions from the secondary free list.
 674     wait_while_free_regions_coming();
 675     append_secondary_free_list_if_not_empty_with_lock();
 676 
 677     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 678     // are lucky enough to find some.
 679     first = _hrm.find_contiguous_only_empty(obj_regions);
 680     if (first != G1_NO_HRM_INDEX) {
 681       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 682     }
 683   }
 684 
 685   if (first == G1_NO_HRM_INDEX) {
 686     // Policy: We could not find enough regions for the humongous object in the
 687     // free list. Look through the heap to find a mix of free and uncommitted regions.
 688     // If so, try expansion.
 689     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 690     if (first != G1_NO_HRM_INDEX) {
 691       // We found something. Make sure these regions are committed, i.e. expand
 692       // the heap. Alternatively we could do a defragmentation GC.
 693       ergo_verbose1(ErgoHeapSizing,
 694                     "attempt heap expansion",
 695                     ergo_format_reason("humongous allocation request failed")
 696                     ergo_format_byte("allocation request"),
 697                     word_size * HeapWordSize);
 698 
 699       _hrm.expand_at(first, obj_regions);
 700       g1_policy()->record_new_heap_size(num_regions());
 701 
 702 #ifdef ASSERT
 703       for (uint i = first; i < first + obj_regions; ++i) {
 704         HeapRegion* hr = region_at(i);
 705         assert(hr->is_free(), "sanity");
 706         assert(hr->is_empty(), "sanity");
 707         assert(is_on_master_free_list(hr), "sanity");
 708       }
 709 #endif
 710       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 711     } else {
 712       // Policy: Potentially trigger a defragmentation GC.
 713     }
 714   }
 715 
 716   HeapWord* result = NULL;
 717   if (first != G1_NO_HRM_INDEX) {
 718     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 719                                                        word_size, context);
 720     assert(result != NULL, "it should always return a valid result");
 721 
 722     // A successful humongous object allocation changes the used space
 723     // information of the old generation so we need to recalculate the
 724     // sizes and update the jstat counters here.
 725     g1mm()->update_sizes();
 726   }
 727 
 728   verify_region_sets_optional();
 729 
 730   return result;
 731 }
 732 
 733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 734   assert_heap_not_locked_and_not_at_safepoint();
 735   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 736 
 737   uint dummy_gc_count_before;
 738   uint dummy_gclocker_retry_count = 0;
 739   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 740 }
 741 
 742 HeapWord*
 743 G1CollectedHeap::mem_allocate(size_t word_size,
 744                               bool*  gc_overhead_limit_was_exceeded) {
 745   assert_heap_not_locked_and_not_at_safepoint();
 746 
 747   // Loop until the allocation is satisfied, or unsatisfied after GC.
 748   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 749     uint gc_count_before;
 750 
 751     HeapWord* result = NULL;
 752     if (!is_humongous(word_size)) {
 753       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 754     } else {
 755       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 756     }
 757     if (result != NULL) {
 758       return result;
 759     }
 760 
 761     // Create the garbage collection operation...
 762     VM_G1CollectForAllocation op(gc_count_before, word_size);
 763     op.set_allocation_context(AllocationContext::current());
 764 
 765     // ...and get the VM thread to execute it.
 766     VMThread::execute(&op);
 767 
 768     if (op.prologue_succeeded() && op.pause_succeeded()) {
 769       // If the operation was successful we'll return the result even
 770       // if it is NULL. If the allocation attempt failed immediately
 771       // after a Full GC, it's unlikely we'll be able to allocate now.
 772       HeapWord* result = op.result();
 773       if (result != NULL && !is_humongous(word_size)) {
 774         // Allocations that take place on VM operations do not do any
 775         // card dirtying and we have to do it here. We only have to do
 776         // this for non-humongous allocations, though.
 777         dirty_young_block(result, word_size);
 778       }
 779       return result;
 780     } else {
 781       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 782         return NULL;
 783       }
 784       assert(op.result() == NULL,
 785              "the result should be NULL if the VM op did not succeed");
 786     }
 787 
 788     // Give a warning if we seem to be looping forever.
 789     if ((QueuedAllocationWarningCount > 0) &&
 790         (try_count % QueuedAllocationWarningCount == 0)) {
 791       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 792     }
 793   }
 794 
 795   ShouldNotReachHere();
 796   return NULL;
 797 }
 798 
 799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 800                                                    AllocationContext_t context,
 801                                                    uint* gc_count_before_ret,
 802                                                    uint* gclocker_retry_count_ret) {
 803   // Make sure you read the note in attempt_allocation_humongous().
 804 
 805   assert_heap_not_locked_and_not_at_safepoint();
 806   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 807          "be called for humongous allocation requests");
 808 
 809   // We should only get here after the first-level allocation attempt
 810   // (attempt_allocation()) failed to allocate.
 811 
 812   // We will loop until a) we manage to successfully perform the
 813   // allocation or b) we successfully schedule a collection which
 814   // fails to perform the allocation. b) is the only case when we'll
 815   // return NULL.
 816   HeapWord* result = NULL;
 817   for (int try_count = 1; /* we'll return */; try_count += 1) {
 818     bool should_try_gc;
 819     uint gc_count_before;
 820 
 821     {
 822       MutexLockerEx x(Heap_lock);
 823       result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
 824                                                                                     false /* bot_updates */);
 825       if (result != NULL) {
 826         return result;
 827       }
 828 
 829       // If we reach here, attempt_allocation_locked() above failed to
 830       // allocate a new region. So the mutator alloc region should be NULL.
 831       assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
 832 
 833       if (GC_locker::is_active_and_needs_gc()) {
 834         if (g1_policy()->can_expand_young_list()) {
 835           // No need for an ergo verbose message here,
 836           // can_expand_young_list() does this when it returns true.
 837           result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
 838                                                                                        false /* bot_updates */);
 839           if (result != NULL) {
 840             return result;
 841           }
 842         }
 843         should_try_gc = false;
 844       } else {
 845         // The GCLocker may not be active but the GCLocker initiated
 846         // GC may not yet have been performed (GCLocker::needs_gc()
 847         // returns true). In this case we do not try this GC and
 848         // wait until the GCLocker initiated GC is performed, and
 849         // then retry the allocation.
 850         if (GC_locker::needs_gc()) {
 851           should_try_gc = false;
 852         } else {
 853           // Read the GC count while still holding the Heap_lock.
 854           gc_count_before = total_collections();
 855           should_try_gc = true;
 856         }
 857       }
 858     }
 859 
 860     if (should_try_gc) {
 861       bool succeeded;
 862       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 863                                    GCCause::_g1_inc_collection_pause);
 864       if (result != NULL) {
 865         assert(succeeded, "only way to get back a non-NULL result");
 866         return result;
 867       }
 868 
 869       if (succeeded) {
 870         // If we get here we successfully scheduled a collection which
 871         // failed to allocate. No point in trying to allocate
 872         // further. We'll just return NULL.
 873         MutexLockerEx x(Heap_lock);
 874         *gc_count_before_ret = total_collections();
 875         return NULL;
 876       }
 877     } else {
 878       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 879         MutexLockerEx x(Heap_lock);
 880         *gc_count_before_ret = total_collections();
 881         return NULL;
 882       }
 883       // The GCLocker is either active or the GCLocker initiated
 884       // GC has not yet been performed. Stall until it is and
 885       // then retry the allocation.
 886       GC_locker::stall_until_clear();
 887       (*gclocker_retry_count_ret) += 1;
 888     }
 889 
 890     // We can reach here if we were unsuccessful in scheduling a
 891     // collection (because another thread beat us to it) or if we were
 892     // stalled due to the GC locker. In either can we should retry the
 893     // allocation attempt in case another thread successfully
 894     // performed a collection and reclaimed enough space. We do the
 895     // first attempt (without holding the Heap_lock) here and the
 896     // follow-on attempt will be at the start of the next loop
 897     // iteration (after taking the Heap_lock).
 898     result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
 899                                                                            false /* bot_updates */);
 900     if (result != NULL) {
 901       return result;
 902     }
 903 
 904     // Give a warning if we seem to be looping forever.
 905     if ((QueuedAllocationWarningCount > 0) &&
 906         (try_count % QueuedAllocationWarningCount == 0)) {
 907       warning("G1CollectedHeap::attempt_allocation_slow() "
 908               "retries %d times", try_count);
 909     }
 910   }
 911 
 912   ShouldNotReachHere();
 913   return NULL;
 914 }
 915 
 916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 917                                                         uint* gc_count_before_ret,
 918                                                         uint* gclocker_retry_count_ret) {
 919   // The structure of this method has a lot of similarities to
 920   // attempt_allocation_slow(). The reason these two were not merged
 921   // into a single one is that such a method would require several "if
 922   // allocation is not humongous do this, otherwise do that"
 923   // conditional paths which would obscure its flow. In fact, an early
 924   // version of this code did use a unified method which was harder to
 925   // follow and, as a result, it had subtle bugs that were hard to
 926   // track down. So keeping these two methods separate allows each to
 927   // be more readable. It will be good to keep these two in sync as
 928   // much as possible.
 929 
 930   assert_heap_not_locked_and_not_at_safepoint();
 931   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 932          "should only be called for humongous allocations");
 933 
 934   // Humongous objects can exhaust the heap quickly, so we should check if we
 935   // need to start a marking cycle at each humongous object allocation. We do
 936   // the check before we do the actual allocation. The reason for doing it
 937   // before the allocation is that we avoid having to keep track of the newly
 938   // allocated memory while we do a GC.
 939   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 940                                            word_size)) {
 941     collect(GCCause::_g1_humongous_allocation);
 942   }
 943 
 944   // We will loop until a) we manage to successfully perform the
 945   // allocation or b) we successfully schedule a collection which
 946   // fails to perform the allocation. b) is the only case when we'll
 947   // return NULL.
 948   HeapWord* result = NULL;
 949   for (int try_count = 1; /* we'll return */; try_count += 1) {
 950     bool should_try_gc;
 951     uint gc_count_before;
 952 
 953     {
 954       MutexLockerEx x(Heap_lock);
 955 
 956       // Given that humongous objects are not allocated in young
 957       // regions, we'll first try to do the allocation without doing a
 958       // collection hoping that there's enough space in the heap.
 959       result = humongous_obj_allocate(word_size, AllocationContext::current());
 960       if (result != NULL) {
 961         return result;
 962       }
 963 
 964       if (GC_locker::is_active_and_needs_gc()) {
 965         should_try_gc = false;
 966       } else {
 967          // The GCLocker may not be active but the GCLocker initiated
 968         // GC may not yet have been performed (GCLocker::needs_gc()
 969         // returns true). In this case we do not try this GC and
 970         // wait until the GCLocker initiated GC is performed, and
 971         // then retry the allocation.
 972         if (GC_locker::needs_gc()) {
 973           should_try_gc = false;
 974         } else {
 975           // Read the GC count while still holding the Heap_lock.
 976           gc_count_before = total_collections();
 977           should_try_gc = true;
 978         }
 979       }
 980     }
 981 
 982     if (should_try_gc) {
 983       // If we failed to allocate the humongous object, we should try to
 984       // do a collection pause (if we're allowed) in case it reclaims
 985       // enough space for the allocation to succeed after the pause.
 986 
 987       bool succeeded;
 988       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 989                                    GCCause::_g1_humongous_allocation);
 990       if (result != NULL) {
 991         assert(succeeded, "only way to get back a non-NULL result");
 992         return result;
 993       }
 994 
 995       if (succeeded) {
 996         // If we get here we successfully scheduled a collection which
 997         // failed to allocate. No point in trying to allocate
 998         // further. We'll just return NULL.
 999         MutexLockerEx x(Heap_lock);
1000         *gc_count_before_ret = total_collections();
1001         return NULL;
1002       }
1003     } else {
1004       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1005         MutexLockerEx x(Heap_lock);
1006         *gc_count_before_ret = total_collections();
1007         return NULL;
1008       }
1009       // The GCLocker is either active or the GCLocker initiated
1010       // GC has not yet been performed. Stall until it is and
1011       // then retry the allocation.
1012       GC_locker::stall_until_clear();
1013       (*gclocker_retry_count_ret) += 1;
1014     }
1015 
1016     // We can reach here if we were unsuccessful in scheduling a
1017     // collection (because another thread beat us to it) or if we were
1018     // stalled due to the GC locker. In either can we should retry the
1019     // allocation attempt in case another thread successfully
1020     // performed a collection and reclaimed enough space.  Give a
1021     // warning if we seem to be looping forever.
1022 
1023     if ((QueuedAllocationWarningCount > 0) &&
1024         (try_count % QueuedAllocationWarningCount == 0)) {
1025       warning("G1CollectedHeap::attempt_allocation_humongous() "
1026               "retries %d times", try_count);
1027     }
1028   }
1029 
1030   ShouldNotReachHere();
1031   return NULL;
1032 }
1033 
1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1035                                                            AllocationContext_t context,
1036                                                            bool expect_null_mutator_alloc_region) {
1037   assert_at_safepoint(true /* should_be_vm_thread */);
1038   assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1039                                              !expect_null_mutator_alloc_region,
1040          "the current alloc region was unexpectedly found to be non-NULL");
1041 
1042   if (!is_humongous(word_size)) {
1043     return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1044                                                       false /* bot_updates */);
1045   } else {
1046     HeapWord* result = humongous_obj_allocate(word_size, context);
1047     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1048       g1_policy()->set_initiate_conc_mark_if_possible();
1049     }
1050     return result;
1051   }
1052 
1053   ShouldNotReachHere();
1054 }
1055 
1056 class PostMCRemSetClearClosure: public HeapRegionClosure {
1057   G1CollectedHeap* _g1h;
1058   ModRefBarrierSet* _mr_bs;
1059 public:
1060   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1061     _g1h(g1h), _mr_bs(mr_bs) {}
1062 
1063   bool doHeapRegion(HeapRegion* r) {
1064     HeapRegionRemSet* hrrs = r->rem_set();
1065 
1066     if (r->is_continues_humongous()) {
1067       // We'll assert that the strong code root list and RSet is empty
1068       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1069       assert(hrrs->occupied() == 0, "RSet should be empty");
1070       return false;
1071     }
1072 
1073     _g1h->reset_gc_time_stamps(r);
1074     hrrs->clear();
1075     // You might think here that we could clear just the cards
1076     // corresponding to the used region.  But no: if we leave a dirty card
1077     // in a region we might allocate into, then it would prevent that card
1078     // from being enqueued, and cause it to be missed.
1079     // Re: the performance cost: we shouldn't be doing full GC anyway!
1080     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1081 
1082     return false;
1083   }
1084 };
1085 
1086 void G1CollectedHeap::clear_rsets_post_compaction() {
1087   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1088   heap_region_iterate(&rs_clear);
1089 }
1090 
1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1092   G1CollectedHeap*   _g1h;
1093   UpdateRSOopClosure _cl;
1094   int                _worker_i;
1095 public:
1096   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1097     _cl(g1->g1_rem_set(), worker_i),
1098     _worker_i(worker_i),
1099     _g1h(g1)
1100   { }
1101 
1102   bool doHeapRegion(HeapRegion* r) {
1103     if (!r->is_continues_humongous()) {
1104       _cl.set_from(r);
1105       r->oop_iterate(&_cl);
1106     }
1107     return false;
1108   }
1109 };
1110 
1111 class ParRebuildRSTask: public AbstractGangTask {
1112   G1CollectedHeap* _g1;
1113   HeapRegionClaimer _hrclaimer;
1114 
1115 public:
1116   ParRebuildRSTask(G1CollectedHeap* g1) :
1117       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1118 
1119   void work(uint worker_id) {
1120     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1121     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1122   }
1123 };
1124 
1125 class PostCompactionPrinterClosure: public HeapRegionClosure {
1126 private:
1127   G1HRPrinter* _hr_printer;
1128 public:
1129   bool doHeapRegion(HeapRegion* hr) {
1130     assert(!hr->is_young(), "not expecting to find young regions");
1131     if (hr->is_free()) {
1132       // We only generate output for non-empty regions.
1133     } else if (hr->is_starts_humongous()) {
1134       if (hr->region_num() == 1) {
1135         // single humongous region
1136         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1137       } else {
1138         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1139       }
1140     } else if (hr->is_continues_humongous()) {
1141       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1142     } else if (hr->is_old()) {
1143       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1144     } else {
1145       ShouldNotReachHere();
1146     }
1147     return false;
1148   }
1149 
1150   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1151     : _hr_printer(hr_printer) { }
1152 };
1153 
1154 void G1CollectedHeap::print_hrm_post_compaction() {
1155   PostCompactionPrinterClosure cl(hr_printer());
1156   heap_region_iterate(&cl);
1157 }
1158 
1159 bool G1CollectedHeap::do_collection(bool explicit_gc,
1160                                     bool clear_all_soft_refs,
1161                                     size_t word_size) {
1162   assert_at_safepoint(true /* should_be_vm_thread */);
1163 
1164   if (GC_locker::check_active_before_gc()) {
1165     return false;
1166   }
1167 
1168   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1169   gc_timer->register_gc_start();
1170 
1171   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1172   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1173 
1174   SvcGCMarker sgcm(SvcGCMarker::FULL);
1175   ResourceMark rm;
1176 
1177   print_heap_before_gc();
1178   trace_heap_before_gc(gc_tracer);
1179 
1180   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1181 
1182   verify_region_sets_optional();
1183 
1184   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1185                            collector_policy()->should_clear_all_soft_refs();
1186 
1187   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1188 
1189   {
1190     IsGCActiveMark x;
1191 
1192     // Timing
1193     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1194     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1195 
1196     {
1197       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1198       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1199       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1200 
1201       g1_policy()->record_full_collection_start();
1202 
1203       // Note: When we have a more flexible GC logging framework that
1204       // allows us to add optional attributes to a GC log record we
1205       // could consider timing and reporting how long we wait in the
1206       // following two methods.
1207       wait_while_free_regions_coming();
1208       // If we start the compaction before the CM threads finish
1209       // scanning the root regions we might trip them over as we'll
1210       // be moving objects / updating references. So let's wait until
1211       // they are done. By telling them to abort, they should complete
1212       // early.
1213       _cm->root_regions()->abort();
1214       _cm->root_regions()->wait_until_scan_finished();
1215       append_secondary_free_list_if_not_empty_with_lock();
1216 
1217       gc_prologue(true);
1218       increment_total_collections(true /* full gc */);
1219       increment_old_marking_cycles_started();
1220 
1221       assert(used() == recalculate_used(), "Should be equal");
1222 
1223       verify_before_gc();
1224 
1225       check_bitmaps("Full GC Start");
1226       pre_full_gc_dump(gc_timer);
1227 
1228       COMPILER2_PRESENT(DerivedPointerTable::clear());
1229 
1230       // Disable discovery and empty the discovered lists
1231       // for the CM ref processor.
1232       ref_processor_cm()->disable_discovery();
1233       ref_processor_cm()->abandon_partial_discovery();
1234       ref_processor_cm()->verify_no_references_recorded();
1235 
1236       // Abandon current iterations of concurrent marking and concurrent
1237       // refinement, if any are in progress. We have to do this before
1238       // wait_until_scan_finished() below.
1239       concurrent_mark()->abort();
1240 
1241       // Make sure we'll choose a new allocation region afterwards.
1242       _allocator->release_mutator_alloc_region();
1243       _allocator->abandon_gc_alloc_regions();
1244       g1_rem_set()->cleanupHRRS();
1245 
1246       // We should call this after we retire any currently active alloc
1247       // regions so that all the ALLOC / RETIRE events are generated
1248       // before the start GC event.
1249       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1250 
1251       // We may have added regions to the current incremental collection
1252       // set between the last GC or pause and now. We need to clear the
1253       // incremental collection set and then start rebuilding it afresh
1254       // after this full GC.
1255       abandon_collection_set(g1_policy()->inc_cset_head());
1256       g1_policy()->clear_incremental_cset();
1257       g1_policy()->stop_incremental_cset_building();
1258 
1259       tear_down_region_sets(false /* free_list_only */);
1260       g1_policy()->set_gcs_are_young(true);
1261 
1262       // See the comments in g1CollectedHeap.hpp and
1263       // G1CollectedHeap::ref_processing_init() about
1264       // how reference processing currently works in G1.
1265 
1266       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1267       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1268 
1269       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1270       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1271 
1272       ref_processor_stw()->enable_discovery();
1273       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1274 
1275       // Do collection work
1276       {
1277         HandleMark hm;  // Discard invalid handles created during gc
1278         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1279       }
1280 
1281       assert(num_free_regions() == 0, "we should not have added any free regions");
1282       rebuild_region_sets(false /* free_list_only */);
1283 
1284       // Enqueue any discovered reference objects that have
1285       // not been removed from the discovered lists.
1286       ref_processor_stw()->enqueue_discovered_references();
1287 
1288       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1289 
1290       MemoryService::track_memory_usage();
1291 
1292       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1293       ref_processor_stw()->verify_no_references_recorded();
1294 
1295       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1296       ClassLoaderDataGraph::purge();
1297       MetaspaceAux::verify_metrics();
1298 
1299       // Note: since we've just done a full GC, concurrent
1300       // marking is no longer active. Therefore we need not
1301       // re-enable reference discovery for the CM ref processor.
1302       // That will be done at the start of the next marking cycle.
1303       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1304       ref_processor_cm()->verify_no_references_recorded();
1305 
1306       reset_gc_time_stamp();
1307       // Since everything potentially moved, we will clear all remembered
1308       // sets, and clear all cards.  Later we will rebuild remembered
1309       // sets. We will also reset the GC time stamps of the regions.
1310       clear_rsets_post_compaction();
1311       check_gc_time_stamps();
1312 
1313       // Resize the heap if necessary.
1314       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1315 
1316       if (_hr_printer.is_active()) {
1317         // We should do this after we potentially resize the heap so
1318         // that all the COMMIT / UNCOMMIT events are generated before
1319         // the end GC event.
1320 
1321         print_hrm_post_compaction();
1322         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1323       }
1324 
1325       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1326       if (hot_card_cache->use_cache()) {
1327         hot_card_cache->reset_card_counts();
1328         hot_card_cache->reset_hot_cache();
1329       }
1330 
1331       // Rebuild remembered sets of all regions.
1332       uint n_workers =
1333         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1334                                                 workers()->active_workers(),
1335                                                 Threads::number_of_non_daemon_threads());
1336       assert(UseDynamicNumberOfGCThreads ||
1337              n_workers == workers()->total_workers(),
1338              "If not dynamic should be using all the  workers");
1339       workers()->set_active_workers(n_workers);
1340       // Set parallel threads in the heap (_n_par_threads) only
1341       // before a parallel phase and always reset it to 0 after
1342       // the phase so that the number of parallel threads does
1343       // no get carried forward to a serial phase where there
1344       // may be code that is "possibly_parallel".
1345       set_par_threads(n_workers);
1346 
1347       ParRebuildRSTask rebuild_rs_task(this);
1348       assert(UseDynamicNumberOfGCThreads ||
1349              workers()->active_workers() == workers()->total_workers(),
1350              "Unless dynamic should use total workers");
1351       // Use the most recent number of  active workers
1352       assert(workers()->active_workers() > 0,
1353              "Active workers not properly set");
1354       set_par_threads(workers()->active_workers());
1355       workers()->run_task(&rebuild_rs_task);
1356       set_par_threads(0);
1357 
1358       // Rebuild the strong code root lists for each region
1359       rebuild_strong_code_roots();
1360 
1361       if (true) { // FIXME
1362         MetaspaceGC::compute_new_size();
1363       }
1364 
1365 #ifdef TRACESPINNING
1366       ParallelTaskTerminator::print_termination_counts();
1367 #endif
1368 
1369       // Discard all rset updates
1370       JavaThread::dirty_card_queue_set().abandon_logs();
1371       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1372 
1373       _young_list->reset_sampled_info();
1374       // At this point there should be no regions in the
1375       // entire heap tagged as young.
1376       assert(check_young_list_empty(true /* check_heap */),
1377              "young list should be empty at this point");
1378 
1379       // Update the number of full collections that have been completed.
1380       increment_old_marking_cycles_completed(false /* concurrent */);
1381 
1382       _hrm.verify_optional();
1383       verify_region_sets_optional();
1384 
1385       verify_after_gc();
1386 
1387       // Clear the previous marking bitmap, if needed for bitmap verification.
1388       // Note we cannot do this when we clear the next marking bitmap in
1389       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1390       // objects marked during a full GC against the previous bitmap.
1391       // But we need to clear it before calling check_bitmaps below since
1392       // the full GC has compacted objects and updated TAMS but not updated
1393       // the prev bitmap.
1394       if (G1VerifyBitmaps) {
1395         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1396       }
1397       check_bitmaps("Full GC End");
1398 
1399       // Start a new incremental collection set for the next pause
1400       assert(g1_policy()->collection_set() == NULL, "must be");
1401       g1_policy()->start_incremental_cset_building();
1402 
1403       clear_cset_fast_test();
1404 
1405       _allocator->init_mutator_alloc_region();
1406 
1407       g1_policy()->record_full_collection_end();
1408 
1409       if (G1Log::fine()) {
1410         g1_policy()->print_heap_transition();
1411       }
1412 
1413       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1414       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1415       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1416       // before any GC notifications are raised.
1417       g1mm()->update_sizes();
1418 
1419       gc_epilogue(true);
1420     }
1421 
1422     if (G1Log::finer()) {
1423       g1_policy()->print_detailed_heap_transition(true /* full */);
1424     }
1425 
1426     print_heap_after_gc();
1427     trace_heap_after_gc(gc_tracer);
1428 
1429     post_full_gc_dump(gc_timer);
1430 
1431     gc_timer->register_gc_end();
1432     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1433   }
1434 
1435   return true;
1436 }
1437 
1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1439   // do_collection() will return whether it succeeded in performing
1440   // the GC. Currently, there is no facility on the
1441   // do_full_collection() API to notify the caller than the collection
1442   // did not succeed (e.g., because it was locked out by the GC
1443   // locker). So, right now, we'll ignore the return value.
1444   bool dummy = do_collection(true,                /* explicit_gc */
1445                              clear_all_soft_refs,
1446                              0                    /* word_size */);
1447 }
1448 
1449 // This code is mostly copied from TenuredGeneration.
1450 void
1451 G1CollectedHeap::
1452 resize_if_necessary_after_full_collection(size_t word_size) {
1453   // Include the current allocation, if any, and bytes that will be
1454   // pre-allocated to support collections, as "used".
1455   const size_t used_after_gc = used();
1456   const size_t capacity_after_gc = capacity();
1457   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1458 
1459   // This is enforced in arguments.cpp.
1460   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1461          "otherwise the code below doesn't make sense");
1462 
1463   // We don't have floating point command-line arguments
1464   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1465   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1466   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1467   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1468 
1469   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1470   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1471 
1472   // We have to be careful here as these two calculations can overflow
1473   // 32-bit size_t's.
1474   double used_after_gc_d = (double) used_after_gc;
1475   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1476   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1477 
1478   // Let's make sure that they are both under the max heap size, which
1479   // by default will make them fit into a size_t.
1480   double desired_capacity_upper_bound = (double) max_heap_size;
1481   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1482                                     desired_capacity_upper_bound);
1483   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1484                                     desired_capacity_upper_bound);
1485 
1486   // We can now safely turn them into size_t's.
1487   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1488   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1489 
1490   // This assert only makes sense here, before we adjust them
1491   // with respect to the min and max heap size.
1492   assert(minimum_desired_capacity <= maximum_desired_capacity,
1493          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1494                  "maximum_desired_capacity = "SIZE_FORMAT,
1495                  minimum_desired_capacity, maximum_desired_capacity));
1496 
1497   // Should not be greater than the heap max size. No need to adjust
1498   // it with respect to the heap min size as it's a lower bound (i.e.,
1499   // we'll try to make the capacity larger than it, not smaller).
1500   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1501   // Should not be less than the heap min size. No need to adjust it
1502   // with respect to the heap max size as it's an upper bound (i.e.,
1503   // we'll try to make the capacity smaller than it, not greater).
1504   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1505 
1506   if (capacity_after_gc < minimum_desired_capacity) {
1507     // Don't expand unless it's significant
1508     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1509     ergo_verbose4(ErgoHeapSizing,
1510                   "attempt heap expansion",
1511                   ergo_format_reason("capacity lower than "
1512                                      "min desired capacity after Full GC")
1513                   ergo_format_byte("capacity")
1514                   ergo_format_byte("occupancy")
1515                   ergo_format_byte_perc("min desired capacity"),
1516                   capacity_after_gc, used_after_gc,
1517                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1518     expand(expand_bytes);
1519 
1520     // No expansion, now see if we want to shrink
1521   } else if (capacity_after_gc > maximum_desired_capacity) {
1522     // Capacity too large, compute shrinking size
1523     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1524     ergo_verbose4(ErgoHeapSizing,
1525                   "attempt heap shrinking",
1526                   ergo_format_reason("capacity higher than "
1527                                      "max desired capacity after Full GC")
1528                   ergo_format_byte("capacity")
1529                   ergo_format_byte("occupancy")
1530                   ergo_format_byte_perc("max desired capacity"),
1531                   capacity_after_gc, used_after_gc,
1532                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1533     shrink(shrink_bytes);
1534   }
1535 }
1536 
1537 
1538 HeapWord*
1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1540                                            AllocationContext_t context,
1541                                            bool* succeeded) {
1542   assert_at_safepoint(true /* should_be_vm_thread */);
1543 
1544   *succeeded = true;
1545   // Let's attempt the allocation first.
1546   HeapWord* result =
1547     attempt_allocation_at_safepoint(word_size,
1548                                     context,
1549                                     false /* expect_null_mutator_alloc_region */);
1550   if (result != NULL) {
1551     assert(*succeeded, "sanity");
1552     return result;
1553   }
1554 
1555   // In a G1 heap, we're supposed to keep allocation from failing by
1556   // incremental pauses.  Therefore, at least for now, we'll favor
1557   // expansion over collection.  (This might change in the future if we can
1558   // do something smarter than full collection to satisfy a failed alloc.)
1559   result = expand_and_allocate(word_size, context);
1560   if (result != NULL) {
1561     assert(*succeeded, "sanity");
1562     return result;
1563   }
1564 
1565   // Expansion didn't work, we'll try to do a Full GC.
1566   bool gc_succeeded = do_collection(false, /* explicit_gc */
1567                                     false, /* clear_all_soft_refs */
1568                                     word_size);
1569   if (!gc_succeeded) {
1570     *succeeded = false;
1571     return NULL;
1572   }
1573 
1574   // Retry the allocation
1575   result = attempt_allocation_at_safepoint(word_size,
1576                                            context,
1577                                            true /* expect_null_mutator_alloc_region */);
1578   if (result != NULL) {
1579     assert(*succeeded, "sanity");
1580     return result;
1581   }
1582 
1583   // Then, try a Full GC that will collect all soft references.
1584   gc_succeeded = do_collection(false, /* explicit_gc */
1585                                true,  /* clear_all_soft_refs */
1586                                word_size);
1587   if (!gc_succeeded) {
1588     *succeeded = false;
1589     return NULL;
1590   }
1591 
1592   // Retry the allocation once more
1593   result = attempt_allocation_at_safepoint(word_size,
1594                                            context,
1595                                            true /* expect_null_mutator_alloc_region */);
1596   if (result != NULL) {
1597     assert(*succeeded, "sanity");
1598     return result;
1599   }
1600 
1601   assert(!collector_policy()->should_clear_all_soft_refs(),
1602          "Flag should have been handled and cleared prior to this point");
1603 
1604   // What else?  We might try synchronous finalization later.  If the total
1605   // space available is large enough for the allocation, then a more
1606   // complete compaction phase than we've tried so far might be
1607   // appropriate.
1608   assert(*succeeded, "sanity");
1609   return NULL;
1610 }
1611 
1612 // Attempting to expand the heap sufficiently
1613 // to support an allocation of the given "word_size".  If
1614 // successful, perform the allocation and return the address of the
1615 // allocated block, or else "NULL".
1616 
1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1618   assert_at_safepoint(true /* should_be_vm_thread */);
1619 
1620   verify_region_sets_optional();
1621 
1622   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1623   ergo_verbose1(ErgoHeapSizing,
1624                 "attempt heap expansion",
1625                 ergo_format_reason("allocation request failed")
1626                 ergo_format_byte("allocation request"),
1627                 word_size * HeapWordSize);
1628   if (expand(expand_bytes)) {
1629     _hrm.verify_optional();
1630     verify_region_sets_optional();
1631     return attempt_allocation_at_safepoint(word_size,
1632                                            context,
1633                                            false /* expect_null_mutator_alloc_region */);
1634   }
1635   return NULL;
1636 }
1637 
1638 bool G1CollectedHeap::expand(size_t expand_bytes) {
1639   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1640   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1641                                        HeapRegion::GrainBytes);
1642   ergo_verbose2(ErgoHeapSizing,
1643                 "expand the heap",
1644                 ergo_format_byte("requested expansion amount")
1645                 ergo_format_byte("attempted expansion amount"),
1646                 expand_bytes, aligned_expand_bytes);
1647 
1648   if (is_maximal_no_gc()) {
1649     ergo_verbose0(ErgoHeapSizing,
1650                       "did not expand the heap",
1651                       ergo_format_reason("heap already fully expanded"));
1652     return false;
1653   }
1654 
1655   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1656   assert(regions_to_expand > 0, "Must expand by at least one region");
1657 
1658   uint expanded_by = _hrm.expand_by(regions_to_expand);
1659 
1660   if (expanded_by > 0) {
1661     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1662     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1663     g1_policy()->record_new_heap_size(num_regions());
1664   } else {
1665     ergo_verbose0(ErgoHeapSizing,
1666                   "did not expand the heap",
1667                   ergo_format_reason("heap expansion operation failed"));
1668     // The expansion of the virtual storage space was unsuccessful.
1669     // Let's see if it was because we ran out of swap.
1670     if (G1ExitOnExpansionFailure &&
1671         _hrm.available() >= regions_to_expand) {
1672       // We had head room...
1673       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1674     }
1675   }
1676   return regions_to_expand > 0;
1677 }
1678 
1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1680   size_t aligned_shrink_bytes =
1681     ReservedSpace::page_align_size_down(shrink_bytes);
1682   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1683                                          HeapRegion::GrainBytes);
1684   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1685 
1686   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1687   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1688 
1689   ergo_verbose3(ErgoHeapSizing,
1690                 "shrink the heap",
1691                 ergo_format_byte("requested shrinking amount")
1692                 ergo_format_byte("aligned shrinking amount")
1693                 ergo_format_byte("attempted shrinking amount"),
1694                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1695   if (num_regions_removed > 0) {
1696     g1_policy()->record_new_heap_size(num_regions());
1697   } else {
1698     ergo_verbose0(ErgoHeapSizing,
1699                   "did not shrink the heap",
1700                   ergo_format_reason("heap shrinking operation failed"));
1701   }
1702 }
1703 
1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705   verify_region_sets_optional();
1706 
1707   // We should only reach here at the end of a Full GC which means we
1708   // should not not be holding to any GC alloc regions. The method
1709   // below will make sure of that and do any remaining clean up.
1710   _allocator->abandon_gc_alloc_regions();
1711 
1712   // Instead of tearing down / rebuilding the free lists here, we
1713   // could instead use the remove_all_pending() method on free_list to
1714   // remove only the ones that we need to remove.
1715   tear_down_region_sets(true /* free_list_only */);
1716   shrink_helper(shrink_bytes);
1717   rebuild_region_sets(true /* free_list_only */);
1718 
1719   _hrm.verify_optional();
1720   verify_region_sets_optional();
1721 }
1722 
1723 // Public methods.
1724 
1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1727 #endif // _MSC_VER
1728 
1729 
1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1731   SharedHeap(),
1732   _g1_policy(policy_),
1733   _dirty_card_queue_set(false),
1734   _into_cset_dirty_card_queue_set(false),
1735   _is_alive_closure_cm(this),
1736   _is_alive_closure_stw(this),
1737   _ref_processor_cm(NULL),
1738   _ref_processor_stw(NULL),
1739   _bot_shared(NULL),
1740   _evac_failure_scan_stack(NULL),
1741   _mark_in_progress(false),
1742   _cg1r(NULL),
1743   _g1mm(NULL),
1744   _refine_cte_cl(NULL),
1745   _full_collection(false),
1746   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1747   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1748   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1749   _humongous_is_live(),
1750   _has_humongous_reclaim_candidates(false),
1751   _free_regions_coming(false),
1752   _young_list(new YoungList(this)),
1753   _gc_time_stamp(0),
1754   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1755   _old_plab_stats(OldPLABSize, PLABWeight),
1756   _expand_heap_after_alloc_failure(true),
1757   _surviving_young_words(NULL),
1758   _old_marking_cycles_started(0),
1759   _old_marking_cycles_completed(0),
1760   _concurrent_cycle_started(false),
1761   _heap_summary_sent(false),
1762   _in_cset_fast_test(),
1763   _dirty_cards_region_list(NULL),
1764   _worker_cset_start_region(NULL),
1765   _worker_cset_start_region_time_stamp(NULL),
1766   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1767   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1768   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1769   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1770 
1771   _g1h = this;
1772 
1773   _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 jint G1CollectedHeap::initialize() {
1806   CollectedHeap::pre_initialize();
1807   os::enable_vtime();
1808 
1809   G1Log::init();
1810 
1811   // Necessary to satisfy locking discipline assertions.
1812 
1813   MutexLocker x(Heap_lock);
1814 
1815   // We have to initialize the printer before committing the heap, as
1816   // it will be used then.
1817   _hr_printer.set_active(G1PrintHeapRegions);
1818 
1819   // While there are no constraints in the GC code that HeapWordSize
1820   // be any particular value, there are multiple other areas in the
1821   // system which believe this to be true (e.g. oop->object_size in some
1822   // cases incorrectly returns the size in wordSize units rather than
1823   // HeapWordSize).
1824   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1825 
1826   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1827   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1828   size_t heap_alignment = collector_policy()->heap_alignment();
1829 
1830   // Ensure that the sizes are properly aligned.
1831   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1832   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1833   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1834 
1835   _refine_cte_cl = new RefineCardTableEntryClosure();
1836 
1837   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1838 
1839   // Reserve the maximum.
1840 
1841   // When compressed oops are enabled, the preferred heap base
1842   // is calculated by subtracting the requested size from the
1843   // 32Gb boundary and using the result as the base address for
1844   // heap reservation. If the requested size is not aligned to
1845   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1846   // into the ReservedHeapSpace constructor) then the actual
1847   // base of the reserved heap may end up differing from the
1848   // address that was requested (i.e. the preferred heap base).
1849   // If this happens then we could end up using a non-optimal
1850   // compressed oops mode.
1851 
1852   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1853                                                  heap_alignment);
1854 
1855   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1856 
1857   // Create the barrier set for the entire reserved region.
1858   G1SATBCardTableLoggingModRefBS* bs
1859     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1860   bs->initialize();
1861   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1862   _barrier_set = bs;
1863   oopDesc::set_bs(bs);
1864 
1865   // Also create a G1 rem set.
1866   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1867 
1868   // Carve out the G1 part of the heap.
1869 
1870   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1871   G1RegionToSpaceMapper* heap_storage =
1872     G1RegionToSpaceMapper::create_mapper(g1_rs,
1873                                          UseLargePages ? os::large_page_size() : os::vm_page_size(),
1874                                          HeapRegion::GrainBytes,
1875                                          1,
1876                                          mtJavaHeap);
1877   heap_storage->set_mapping_changed_listener(&_listener);
1878 
1879   // Reserve space for the block offset table. We do not support automatic uncommit
1880   // for the card table at this time. BOT only.
1881   ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1882   G1RegionToSpaceMapper* bot_storage =
1883     G1RegionToSpaceMapper::create_mapper(bot_rs,
1884                                          os::vm_page_size(),
1885                                          HeapRegion::GrainBytes,
1886                                          G1BlockOffsetSharedArray::N_bytes,
1887                                          mtGC);
1888 
1889   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1890   G1RegionToSpaceMapper* cardtable_storage =
1891     G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1892                                          os::vm_page_size(),
1893                                          HeapRegion::GrainBytes,
1894                                          G1BlockOffsetSharedArray::N_bytes,
1895                                          mtGC);
1896 
1897   // Reserve space for the card counts table.
1898   ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1899   G1RegionToSpaceMapper* card_counts_storage =
1900     G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1901                                          os::vm_page_size(),
1902                                          HeapRegion::GrainBytes,
1903                                          G1BlockOffsetSharedArray::N_bytes,
1904                                          mtGC);
1905 
1906   // Reserve space for prev and next bitmap.
1907   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1908 
1909   ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1910   G1RegionToSpaceMapper* prev_bitmap_storage =
1911     G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1912                                          os::vm_page_size(),
1913                                          HeapRegion::GrainBytes,
1914                                          CMBitMap::mark_distance(),
1915                                          mtGC);
1916 
1917   ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1918   G1RegionToSpaceMapper* next_bitmap_storage =
1919     G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1920                                          os::vm_page_size(),
1921                                          HeapRegion::GrainBytes,
1922                                          CMBitMap::mark_distance(),
1923                                          mtGC);
1924 
1925   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1926   g1_barrier_set()->initialize(cardtable_storage);
1927    // Do later initialization work for concurrent refinement.
1928   _cg1r->init(card_counts_storage);
1929 
1930   // 6843694 - ensure that the maximum region index can fit
1931   // in the remembered set structures.
1932   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1933   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1934 
1935   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1936   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1937   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1938             "too many cards per region");
1939 
1940   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1941 
1942   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1943 
1944   _g1h = this;
1945 
1946   _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1947   _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1948 
1949   // Create the ConcurrentMark data structure and thread.
1950   // (Must do this late, so that "max_regions" is defined.)
1951   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1952   if (_cm == NULL || !_cm->completed_initialization()) {
1953     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1954     return JNI_ENOMEM;
1955   }
1956   _cmThread = _cm->cmThread();
1957 
1958   // Initialize the from_card cache structure of HeapRegionRemSet.
1959   HeapRegionRemSet::init_heap(max_regions());
1960 
1961   // Now expand into the initial heap size.
1962   if (!expand(init_byte_size)) {
1963     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1964     return JNI_ENOMEM;
1965   }
1966 
1967   // Perform any initialization actions delegated to the policy.
1968   g1_policy()->init();
1969 
1970   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1971                                                SATB_Q_FL_lock,
1972                                                G1SATBProcessCompletedThreshold,
1973                                                Shared_SATB_Q_lock);
1974 
1975   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1976                                                 DirtyCardQ_CBL_mon,
1977                                                 DirtyCardQ_FL_lock,
1978                                                 concurrent_g1_refine()->yellow_zone(),
1979                                                 concurrent_g1_refine()->red_zone(),
1980                                                 Shared_DirtyCardQ_lock);
1981 
1982   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1983                                     DirtyCardQ_CBL_mon,
1984                                     DirtyCardQ_FL_lock,
1985                                     -1, // never trigger processing
1986                                     -1, // no limit on length
1987                                     Shared_DirtyCardQ_lock,
1988                                     &JavaThread::dirty_card_queue_set());
1989 
1990   // Initialize the card queue set used to hold cards containing
1991   // references into the collection set.
1992   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1993                                              DirtyCardQ_CBL_mon,
1994                                              DirtyCardQ_FL_lock,
1995                                              -1, // never trigger processing
1996                                              -1, // no limit on length
1997                                              Shared_DirtyCardQ_lock,
1998                                              &JavaThread::dirty_card_queue_set());
1999 
2000   // Here we allocate the dummy HeapRegion that is required by the
2001   // G1AllocRegion class.
2002   HeapRegion* dummy_region = _hrm.get_dummy_region();
2003 
2004   // We'll re-use the same region whether the alloc region will
2005   // require BOT updates or not and, if it doesn't, then a non-young
2006   // region will complain that it cannot support allocations without
2007   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2008   dummy_region->set_eden();
2009   // Make sure it's full.
2010   dummy_region->set_top(dummy_region->end());
2011   G1AllocRegion::setup(this, dummy_region);
2012 
2013   _allocator->init_mutator_alloc_region();
2014 
2015   // Do create of the monitoring and management support so that
2016   // values in the heap have been properly initialized.
2017   _g1mm = new G1MonitoringSupport(this);
2018 
2019   G1StringDedup::initialize();
2020 
2021   return JNI_OK;
2022 }
2023 
2024 void G1CollectedHeap::stop() {
2025   // Stop all concurrent threads. We do this to make sure these threads
2026   // do not continue to execute and access resources (e.g. gclog_or_tty)
2027   // that are destroyed during shutdown.
2028   _cg1r->stop();
2029   _cmThread->stop();
2030   if (G1StringDedup::is_enabled()) {
2031     G1StringDedup::stop();
2032   }
2033 }
2034 
2035 void G1CollectedHeap::clear_humongous_is_live_table() {
2036   guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2037   _humongous_is_live.clear();
2038 }
2039 
2040 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2041   return HeapRegion::max_region_size();
2042 }
2043 
2044 void G1CollectedHeap::post_initialize() {
2045   CollectedHeap::post_initialize();
2046   ref_processing_init();
2047 }
2048 
2049 void G1CollectedHeap::ref_processing_init() {
2050   // Reference processing in G1 currently works as follows:
2051   //
2052   // * There are two reference processor instances. One is
2053   //   used to record and process discovered references
2054   //   during concurrent marking; the other is used to
2055   //   record and process references during STW pauses
2056   //   (both full and incremental).
2057   // * Both ref processors need to 'span' the entire heap as
2058   //   the regions in the collection set may be dotted around.
2059   //
2060   // * For the concurrent marking ref processor:
2061   //   * Reference discovery is enabled at initial marking.
2062   //   * Reference discovery is disabled and the discovered
2063   //     references processed etc during remarking.
2064   //   * Reference discovery is MT (see below).
2065   //   * Reference discovery requires a barrier (see below).
2066   //   * Reference processing may or may not be MT
2067   //     (depending on the value of ParallelRefProcEnabled
2068   //     and ParallelGCThreads).
2069   //   * A full GC disables reference discovery by the CM
2070   //     ref processor and abandons any entries on it's
2071   //     discovered lists.
2072   //
2073   // * For the STW processor:
2074   //   * Non MT discovery is enabled at the start of a full GC.
2075   //   * Processing and enqueueing during a full GC is non-MT.
2076   //   * During a full GC, references are processed after marking.
2077   //
2078   //   * Discovery (may or may not be MT) is enabled at the start
2079   //     of an incremental evacuation pause.
2080   //   * References are processed near the end of a STW evacuation pause.
2081   //   * For both types of GC:
2082   //     * Discovery is atomic - i.e. not concurrent.
2083   //     * Reference discovery will not need a barrier.
2084 
2085   MemRegion mr = reserved_region();
2086 
2087   // Concurrent Mark ref processor
2088   _ref_processor_cm =
2089     new ReferenceProcessor(mr,    // span
2090                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2091                                 // mt processing
2092                            (int) ParallelGCThreads,
2093                                 // degree of mt processing
2094                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2095                                 // mt discovery
2096                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2097                                 // degree of mt discovery
2098                            false,
2099                                 // Reference discovery is not atomic
2100                            &_is_alive_closure_cm);
2101                                 // is alive closure
2102                                 // (for efficiency/performance)
2103 
2104   // STW ref processor
2105   _ref_processor_stw =
2106     new ReferenceProcessor(mr,    // span
2107                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2108                                 // mt processing
2109                            MAX2((int)ParallelGCThreads, 1),
2110                                 // degree of mt processing
2111                            (ParallelGCThreads > 1),
2112                                 // mt discovery
2113                            MAX2((int)ParallelGCThreads, 1),
2114                                 // degree of mt discovery
2115                            true,
2116                                 // Reference discovery is atomic
2117                            &_is_alive_closure_stw);
2118                                 // is alive closure
2119                                 // (for efficiency/performance)
2120 }
2121 
2122 size_t G1CollectedHeap::capacity() const {
2123   return _hrm.length() * HeapRegion::GrainBytes;
2124 }
2125 
2126 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2127   assert(!hr->is_continues_humongous(), "pre-condition");
2128   hr->reset_gc_time_stamp();
2129   if (hr->is_starts_humongous()) {
2130     uint first_index = hr->hrm_index() + 1;
2131     uint last_index = hr->last_hc_index();
2132     for (uint i = first_index; i < last_index; i += 1) {
2133       HeapRegion* chr = region_at(i);
2134       assert(chr->is_continues_humongous(), "sanity");
2135       chr->reset_gc_time_stamp();
2136     }
2137   }
2138 }
2139 
2140 #ifndef PRODUCT
2141 
2142 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2143 private:
2144   unsigned _gc_time_stamp;
2145   bool _failures;
2146 
2147 public:
2148   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2149     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2150 
2151   virtual bool doHeapRegion(HeapRegion* hr) {
2152     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2153     if (_gc_time_stamp != region_gc_time_stamp) {
2154       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2155                              "expected %d", HR_FORMAT_PARAMS(hr),
2156                              region_gc_time_stamp, _gc_time_stamp);
2157       _failures = true;
2158     }
2159     return false;
2160   }
2161 
2162   bool failures() { return _failures; }
2163 };
2164 
2165 void G1CollectedHeap::check_gc_time_stamps() {
2166   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2167   heap_region_iterate(&cl);
2168   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2169 }
2170 
2171 void G1CollectedHeap::set_heap_lock_held_for_gc(bool value) {
2172   _thread_holds_heap_lock_for_gc = value;
2173 }
2174 
2175 bool G1CollectedHeap::heap_lock_held_for_gc() {
2176   Thread* t = Thread::current();
2177   return    Heap_lock->owned_by_self()
2178          || (   (t->is_GC_task_thread() ||  t->is_VM_thread())
2179              && _thread_holds_heap_lock_for_gc);
2180 }
2181 
2182 #endif // PRODUCT
2183 
2184 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2185                                                  DirtyCardQueue* into_cset_dcq,
2186                                                  bool concurrent,
2187                                                  uint worker_i) {
2188   // Clean cards in the hot card cache
2189   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2190   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2191 
2192   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2193   size_t n_completed_buffers = 0;
2194   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2195     n_completed_buffers++;
2196   }
2197   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2198   dcqs.clear_n_completed_buffers();
2199   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2200 }
2201 
2202 
2203 // Computes the sum of the storage used by the various regions.
2204 size_t G1CollectedHeap::used() const {
2205   return _allocator->used();
2206 }
2207 
2208 size_t G1CollectedHeap::used_unlocked() const {
2209   return _allocator->used_unlocked();
2210 }
2211 
2212 class SumUsedClosure: public HeapRegionClosure {
2213   size_t _used;
2214 public:
2215   SumUsedClosure() : _used(0) {}
2216   bool doHeapRegion(HeapRegion* r) {
2217     if (!r->is_continues_humongous()) {
2218       _used += r->used();
2219     }
2220     return false;
2221   }
2222   size_t result() { return _used; }
2223 };
2224 
2225 size_t G1CollectedHeap::recalculate_used() const {
2226   double recalculate_used_start = os::elapsedTime();
2227 
2228   SumUsedClosure blk;
2229   heap_region_iterate(&blk);
2230 
2231   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2232   return blk.result();
2233 }
2234 
2235 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2236   switch (cause) {
2237     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2238     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2239     case GCCause::_g1_humongous_allocation: return true;
2240     case GCCause::_update_allocation_context_stats_inc: return true;
2241     case GCCause::_wb_conc_mark:            return true;
2242     default:                                return false;
2243   }
2244 }
2245 
2246 #ifndef PRODUCT
2247 void G1CollectedHeap::allocate_dummy_regions() {
2248   // Let's fill up most of the region
2249   size_t word_size = HeapRegion::GrainWords - 1024;
2250   // And as a result the region we'll allocate will be humongous.
2251   guarantee(is_humongous(word_size), "sanity");
2252 
2253   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2254     // Let's use the existing mechanism for the allocation
2255     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2256                                                  AllocationContext::system());
2257     if (dummy_obj != NULL) {
2258       MemRegion mr(dummy_obj, word_size);
2259       CollectedHeap::fill_with_object(mr);
2260     } else {
2261       // If we can't allocate once, we probably cannot allocate
2262       // again. Let's get out of the loop.
2263       break;
2264     }
2265   }
2266 }
2267 #endif // !PRODUCT
2268 
2269 void G1CollectedHeap::increment_old_marking_cycles_started() {
2270   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2271     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2272     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2273     _old_marking_cycles_started, _old_marking_cycles_completed));
2274 
2275   _old_marking_cycles_started++;
2276 }
2277 
2278 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2279   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2280 
2281   // We assume that if concurrent == true, then the caller is a
2282   // concurrent thread that was joined the Suspendible Thread
2283   // Set. If there's ever a cheap way to check this, we should add an
2284   // assert here.
2285 
2286   // Given that this method is called at the end of a Full GC or of a
2287   // concurrent cycle, and those can be nested (i.e., a Full GC can
2288   // interrupt a concurrent cycle), the number of full collections
2289   // completed should be either one (in the case where there was no
2290   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2291   // behind the number of full collections started.
2292 
2293   // This is the case for the inner caller, i.e. a Full GC.
2294   assert(concurrent ||
2295          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2296          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2297          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2298                  "is inconsistent with _old_marking_cycles_completed = %u",
2299                  _old_marking_cycles_started, _old_marking_cycles_completed));
2300 
2301   // This is the case for the outer caller, i.e. the concurrent cycle.
2302   assert(!concurrent ||
2303          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2304          err_msg("for outer caller (concurrent cycle): "
2305                  "_old_marking_cycles_started = %u "
2306                  "is inconsistent with _old_marking_cycles_completed = %u",
2307                  _old_marking_cycles_started, _old_marking_cycles_completed));
2308 
2309   _old_marking_cycles_completed += 1;
2310 
2311   // We need to clear the "in_progress" flag in the CM thread before
2312   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2313   // is set) so that if a waiter requests another System.gc() it doesn't
2314   // incorrectly see that a marking cycle is still in progress.
2315   if (concurrent) {
2316     _cmThread->clear_in_progress();
2317   }
2318 
2319   // This notify_all() will ensure that a thread that called
2320   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2321   // and it's waiting for a full GC to finish will be woken up. It is
2322   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2323   FullGCCount_lock->notify_all();
2324 }
2325 
2326 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2327   _concurrent_cycle_started = true;
2328   _gc_timer_cm->register_gc_start(start_time);
2329 
2330   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2331   trace_heap_before_gc(_gc_tracer_cm);
2332 }
2333 
2334 void G1CollectedHeap::register_concurrent_cycle_end() {
2335   if (_concurrent_cycle_started) {
2336     if (_cm->has_aborted()) {
2337       _gc_tracer_cm->report_concurrent_mode_failure();
2338     }
2339 
2340     _gc_timer_cm->register_gc_end();
2341     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2342 
2343     // Clear state variables to prepare for the next concurrent cycle.
2344     _concurrent_cycle_started = false;
2345     _heap_summary_sent = false;
2346   }
2347 }
2348 
2349 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2350   if (_concurrent_cycle_started) {
2351     // This function can be called when:
2352     //  the cleanup pause is run
2353     //  the concurrent cycle is aborted before the cleanup pause.
2354     //  the concurrent cycle is aborted after the cleanup pause,
2355     //   but before the concurrent cycle end has been registered.
2356     // Make sure that we only send the heap information once.
2357     if (!_heap_summary_sent) {
2358       trace_heap_after_gc(_gc_tracer_cm);
2359       _heap_summary_sent = true;
2360     }
2361   }
2362 }
2363 
2364 G1YCType G1CollectedHeap::yc_type() {
2365   bool is_young = g1_policy()->gcs_are_young();
2366   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2367   bool is_during_mark = mark_in_progress();
2368 
2369   if (is_initial_mark) {
2370     return InitialMark;
2371   } else if (is_during_mark) {
2372     return DuringMark;
2373   } else if (is_young) {
2374     return Normal;
2375   } else {
2376     return Mixed;
2377   }
2378 }
2379 
2380 void G1CollectedHeap::collect(GCCause::Cause cause) {
2381   assert_heap_not_locked();
2382 
2383   uint gc_count_before;
2384   uint old_marking_count_before;
2385   uint full_gc_count_before;
2386   bool retry_gc;
2387 
2388   do {
2389     retry_gc = false;
2390 
2391     {
2392       MutexLocker ml(Heap_lock);
2393 
2394       // Read the GC count while holding the Heap_lock
2395       gc_count_before = total_collections();
2396       full_gc_count_before = total_full_collections();
2397       old_marking_count_before = _old_marking_cycles_started;
2398     }
2399 
2400     if (should_do_concurrent_full_gc(cause)) {
2401       // Schedule an initial-mark evacuation pause that will start a
2402       // concurrent cycle. We're setting word_size to 0 which means that
2403       // we are not requesting a post-GC allocation.
2404       VM_G1IncCollectionPause op(gc_count_before,
2405                                  0,     /* word_size */
2406                                  true,  /* should_initiate_conc_mark */
2407                                  g1_policy()->max_pause_time_ms(),
2408                                  cause);
2409       op.set_allocation_context(AllocationContext::current());
2410 
2411       VMThread::execute(&op);
2412       if (!op.pause_succeeded()) {
2413         if (old_marking_count_before == _old_marking_cycles_started) {
2414           retry_gc = op.should_retry_gc();
2415         } else {
2416           // A Full GC happened while we were trying to schedule the
2417           // initial-mark GC. No point in starting a new cycle given
2418           // that the whole heap was collected anyway.
2419         }
2420 
2421         if (retry_gc) {
2422           if (GC_locker::is_active_and_needs_gc()) {
2423             GC_locker::stall_until_clear();
2424           }
2425         }
2426       }
2427     } else {
2428       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2429           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2430 
2431         // Schedule a standard evacuation pause. We're setting word_size
2432         // to 0 which means that we are not requesting a post-GC allocation.
2433         VM_G1IncCollectionPause op(gc_count_before,
2434                                    0,     /* word_size */
2435                                    false, /* should_initiate_conc_mark */
2436                                    g1_policy()->max_pause_time_ms(),
2437                                    cause);
2438         VMThread::execute(&op);
2439       } else {
2440         // Schedule a Full GC.
2441         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2442         VMThread::execute(&op);
2443       }
2444     }
2445   } while (retry_gc);
2446 }
2447 
2448 bool G1CollectedHeap::is_in(const void* p) const {
2449   if (_hrm.reserved().contains(p)) {
2450     // Given that we know that p is in the reserved space,
2451     // heap_region_containing_raw() should successfully
2452     // return the containing region.
2453     HeapRegion* hr = heap_region_containing_raw(p);
2454     return hr->is_in(p);
2455   } else {
2456     return false;
2457   }
2458 }
2459 
2460 #ifdef ASSERT
2461 bool G1CollectedHeap::is_in_exact(const void* p) const {
2462   bool contains = reserved_region().contains(p);
2463   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2464   if (contains && available) {
2465     return true;
2466   } else {
2467     return false;
2468   }
2469 }
2470 #endif
2471 
2472 // Iteration functions.
2473 
2474 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2475 
2476 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2477   ExtendedOopClosure* _cl;
2478 public:
2479   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2480   bool doHeapRegion(HeapRegion* r) {
2481     if (!r->is_continues_humongous()) {
2482       r->oop_iterate(_cl);
2483     }
2484     return false;
2485   }
2486 };
2487 
2488 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2489   IterateOopClosureRegionClosure blk(cl);
2490   heap_region_iterate(&blk);
2491 }
2492 
2493 // Iterates an ObjectClosure over all objects within a HeapRegion.
2494 
2495 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2496   ObjectClosure* _cl;
2497 public:
2498   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2499   bool doHeapRegion(HeapRegion* r) {
2500     if (!r->is_continues_humongous()) {
2501       r->object_iterate(_cl);
2502     }
2503     return false;
2504   }
2505 };
2506 
2507 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2508   IterateObjectClosureRegionClosure blk(cl);
2509   heap_region_iterate(&blk);
2510 }
2511 
2512 // Calls a SpaceClosure on a HeapRegion.
2513 
2514 class SpaceClosureRegionClosure: public HeapRegionClosure {
2515   SpaceClosure* _cl;
2516 public:
2517   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2518   bool doHeapRegion(HeapRegion* r) {
2519     _cl->do_space(r);
2520     return false;
2521   }
2522 };
2523 
2524 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2525   _hrm.iterate(cl);
2526 }
2527 
2528 void
2529 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2530                                          uint worker_id,
2531                                          HeapRegionClaimer *hrclaimer,
2532                                          bool concurrent) const {
2533   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2534 }
2535 
2536 // Clear the cached CSet starting regions and (more importantly)
2537 // the time stamps. Called when we reset the GC time stamp.
2538 void G1CollectedHeap::clear_cset_start_regions() {
2539   assert(_worker_cset_start_region != NULL, "sanity");
2540   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2541 
2542   int n_queues = MAX2((int)ParallelGCThreads, 1);
2543   for (int i = 0; i < n_queues; i++) {
2544     _worker_cset_start_region[i] = NULL;
2545     _worker_cset_start_region_time_stamp[i] = 0;
2546   }
2547 }
2548 
2549 // Given the id of a worker, obtain or calculate a suitable
2550 // starting region for iterating over the current collection set.
2551 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2552   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2553 
2554   HeapRegion* result = NULL;
2555   unsigned gc_time_stamp = get_gc_time_stamp();
2556 
2557   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2558     // Cached starting region for current worker was set
2559     // during the current pause - so it's valid.
2560     // Note: the cached starting heap region may be NULL
2561     // (when the collection set is empty).
2562     result = _worker_cset_start_region[worker_i];
2563     assert(result == NULL || result->in_collection_set(), "sanity");
2564     return result;
2565   }
2566 
2567   // The cached entry was not valid so let's calculate
2568   // a suitable starting heap region for this worker.
2569 
2570   // We want the parallel threads to start their collection
2571   // set iteration at different collection set regions to
2572   // avoid contention.
2573   // If we have:
2574   //          n collection set regions
2575   //          p threads
2576   // Then thread t will start at region floor ((t * n) / p)
2577 
2578   result = g1_policy()->collection_set();
2579   uint cs_size = g1_policy()->cset_region_length();
2580   uint active_workers = workers()->active_workers();
2581   assert(UseDynamicNumberOfGCThreads ||
2582            active_workers == workers()->total_workers(),
2583            "Unless dynamic should use total workers");
2584 
2585   uint end_ind   = (cs_size * worker_i) / active_workers;
2586   uint start_ind = 0;
2587 
2588   if (worker_i > 0 &&
2589       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2590     // Previous workers starting region is valid
2591     // so let's iterate from there
2592     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2593     result = _worker_cset_start_region[worker_i - 1];
2594   }
2595 
2596   for (uint i = start_ind; i < end_ind; i++) {
2597     result = result->next_in_collection_set();
2598   }
2599 
2600   // Note: the calculated starting heap region may be NULL
2601   // (when the collection set is empty).
2602   assert(result == NULL || result->in_collection_set(), "sanity");
2603   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2604          "should be updated only once per pause");
2605   _worker_cset_start_region[worker_i] = result;
2606   OrderAccess::storestore();
2607   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2608   return result;
2609 }
2610 
2611 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2612   HeapRegion* r = g1_policy()->collection_set();
2613   while (r != NULL) {
2614     HeapRegion* next = r->next_in_collection_set();
2615     if (cl->doHeapRegion(r)) {
2616       cl->incomplete();
2617       return;
2618     }
2619     r = next;
2620   }
2621 }
2622 
2623 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2624                                                   HeapRegionClosure *cl) {
2625   if (r == NULL) {
2626     // The CSet is empty so there's nothing to do.
2627     return;
2628   }
2629 
2630   assert(r->in_collection_set(),
2631          "Start region must be a member of the collection set.");
2632   HeapRegion* cur = r;
2633   while (cur != NULL) {
2634     HeapRegion* next = cur->next_in_collection_set();
2635     if (cl->doHeapRegion(cur) && false) {
2636       cl->incomplete();
2637       return;
2638     }
2639     cur = next;
2640   }
2641   cur = g1_policy()->collection_set();
2642   while (cur != r) {
2643     HeapRegion* next = cur->next_in_collection_set();
2644     if (cl->doHeapRegion(cur) && false) {
2645       cl->incomplete();
2646       return;
2647     }
2648     cur = next;
2649   }
2650 }
2651 
2652 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2653   HeapRegion* result = _hrm.next_region_in_heap(from);
2654   while (result != NULL && result->is_humongous()) {
2655     result = _hrm.next_region_in_heap(result);
2656   }
2657   return result;
2658 }
2659 
2660 Space* G1CollectedHeap::space_containing(const void* addr) const {
2661   return heap_region_containing(addr);
2662 }
2663 
2664 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2665   Space* sp = space_containing(addr);
2666   return sp->block_start(addr);
2667 }
2668 
2669 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2670   Space* sp = space_containing(addr);
2671   return sp->block_size(addr);
2672 }
2673 
2674 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2675   Space* sp = space_containing(addr);
2676   return sp->block_is_obj(addr);
2677 }
2678 
2679 bool G1CollectedHeap::supports_tlab_allocation() const {
2680   return true;
2681 }
2682 
2683 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2684   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2685 }
2686 
2687 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2688   return young_list()->eden_used_bytes();
2689 }
2690 
2691 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2692 // must be smaller than the humongous object limit.
2693 size_t G1CollectedHeap::max_tlab_size() const {
2694   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2695 }
2696 
2697 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2698   // Return the remaining space in the cur alloc region, but not less than
2699   // the min TLAB size.
2700 
2701   // Also, this value can be at most the humongous object threshold,
2702   // since we can't allow tlabs to grow big enough to accommodate
2703   // humongous objects.
2704 
2705   HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2706   size_t max_tlab = max_tlab_size() * wordSize;
2707   if (hr == NULL) {
2708     return max_tlab;
2709   } else {
2710     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2711   }
2712 }
2713 
2714 size_t G1CollectedHeap::max_capacity() const {
2715   return _hrm.reserved().byte_size();
2716 }
2717 
2718 jlong G1CollectedHeap::millis_since_last_gc() {
2719   // assert(false, "NYI");
2720   return 0;
2721 }
2722 
2723 void G1CollectedHeap::prepare_for_verify() {
2724   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2725     ensure_parsability(false);
2726   }
2727   g1_rem_set()->prepare_for_verify();
2728 }
2729 
2730 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2731                                               VerifyOption vo) {
2732   switch (vo) {
2733   case VerifyOption_G1UsePrevMarking:
2734     return hr->obj_allocated_since_prev_marking(obj);
2735   case VerifyOption_G1UseNextMarking:
2736     return hr->obj_allocated_since_next_marking(obj);
2737   case VerifyOption_G1UseMarkWord:
2738     return false;
2739   default:
2740     ShouldNotReachHere();
2741   }
2742   return false; // keep some compilers happy
2743 }
2744 
2745 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2746   switch (vo) {
2747   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2748   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2749   case VerifyOption_G1UseMarkWord:    return NULL;
2750   default:                            ShouldNotReachHere();
2751   }
2752   return NULL; // keep some compilers happy
2753 }
2754 
2755 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2756   switch (vo) {
2757   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2758   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2759   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2760   default:                            ShouldNotReachHere();
2761   }
2762   return false; // keep some compilers happy
2763 }
2764 
2765 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2766   switch (vo) {
2767   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2768   case VerifyOption_G1UseNextMarking: return "NTAMS";
2769   case VerifyOption_G1UseMarkWord:    return "NONE";
2770   default:                            ShouldNotReachHere();
2771   }
2772   return NULL; // keep some compilers happy
2773 }
2774 
2775 class VerifyRootsClosure: public OopClosure {
2776 private:
2777   G1CollectedHeap* _g1h;
2778   VerifyOption     _vo;
2779   bool             _failures;
2780 public:
2781   // _vo == UsePrevMarking -> use "prev" marking information,
2782   // _vo == UseNextMarking -> use "next" marking information,
2783   // _vo == UseMarkWord    -> use mark word from object header.
2784   VerifyRootsClosure(VerifyOption vo) :
2785     _g1h(G1CollectedHeap::heap()),
2786     _vo(vo),
2787     _failures(false) { }
2788 
2789   bool failures() { return _failures; }
2790 
2791   template <class T> void do_oop_nv(T* p) {
2792     T heap_oop = oopDesc::load_heap_oop(p);
2793     if (!oopDesc::is_null(heap_oop)) {
2794       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2795       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2796         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2797                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2798         if (_vo == VerifyOption_G1UseMarkWord) {
2799           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2800         }
2801         obj->print_on(gclog_or_tty);
2802         _failures = true;
2803       }
2804     }
2805   }
2806 
2807   void do_oop(oop* p)       { do_oop_nv(p); }
2808   void do_oop(narrowOop* p) { do_oop_nv(p); }
2809 };
2810 
2811 class G1VerifyCodeRootOopClosure: public OopClosure {
2812   G1CollectedHeap* _g1h;
2813   OopClosure* _root_cl;
2814   nmethod* _nm;
2815   VerifyOption _vo;
2816   bool _failures;
2817 
2818   template <class T> void do_oop_work(T* p) {
2819     // First verify that this root is live
2820     _root_cl->do_oop(p);
2821 
2822     if (!G1VerifyHeapRegionCodeRoots) {
2823       // We're not verifying the code roots attached to heap region.
2824       return;
2825     }
2826 
2827     // Don't check the code roots during marking verification in a full GC
2828     if (_vo == VerifyOption_G1UseMarkWord) {
2829       return;
2830     }
2831 
2832     // Now verify that the current nmethod (which contains p) is
2833     // in the code root list of the heap region containing the
2834     // object referenced by p.
2835 
2836     T heap_oop = oopDesc::load_heap_oop(p);
2837     if (!oopDesc::is_null(heap_oop)) {
2838       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2839 
2840       // Now fetch the region containing the object
2841       HeapRegion* hr = _g1h->heap_region_containing(obj);
2842       HeapRegionRemSet* hrrs = hr->rem_set();
2843       // Verify that the strong code root list for this region
2844       // contains the nmethod
2845       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2846         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2847                               "from nmethod "PTR_FORMAT" not in strong "
2848                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2849                               p, _nm, hr->bottom(), hr->end());
2850         _failures = true;
2851       }
2852     }
2853   }
2854 
2855 public:
2856   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2857     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2858 
2859   void do_oop(oop* p) { do_oop_work(p); }
2860   void do_oop(narrowOop* p) { do_oop_work(p); }
2861 
2862   void set_nmethod(nmethod* nm) { _nm = nm; }
2863   bool failures() { return _failures; }
2864 };
2865 
2866 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2867   G1VerifyCodeRootOopClosure* _oop_cl;
2868 
2869 public:
2870   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2871     _oop_cl(oop_cl) {}
2872 
2873   void do_code_blob(CodeBlob* cb) {
2874     nmethod* nm = cb->as_nmethod_or_null();
2875     if (nm != NULL) {
2876       _oop_cl->set_nmethod(nm);
2877       nm->oops_do(_oop_cl);
2878     }
2879   }
2880 };
2881 
2882 class YoungRefCounterClosure : public OopClosure {
2883   G1CollectedHeap* _g1h;
2884   int              _count;
2885  public:
2886   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2887   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2888   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2889 
2890   int count() { return _count; }
2891   void reset_count() { _count = 0; };
2892 };
2893 
2894 class VerifyKlassClosure: public KlassClosure {
2895   YoungRefCounterClosure _young_ref_counter_closure;
2896   OopClosure *_oop_closure;
2897  public:
2898   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2899   void do_klass(Klass* k) {
2900     k->oops_do(_oop_closure);
2901 
2902     _young_ref_counter_closure.reset_count();
2903     k->oops_do(&_young_ref_counter_closure);
2904     if (_young_ref_counter_closure.count() > 0) {
2905       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2906     }
2907   }
2908 };
2909 
2910 class VerifyLivenessOopClosure: public OopClosure {
2911   G1CollectedHeap* _g1h;
2912   VerifyOption _vo;
2913 public:
2914   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2915     _g1h(g1h), _vo(vo)
2916   { }
2917   void do_oop(narrowOop *p) { do_oop_work(p); }
2918   void do_oop(      oop *p) { do_oop_work(p); }
2919 
2920   template <class T> void do_oop_work(T *p) {
2921     oop obj = oopDesc::load_decode_heap_oop(p);
2922     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2923               "Dead object referenced by a not dead object");
2924   }
2925 };
2926 
2927 class VerifyObjsInRegionClosure: public ObjectClosure {
2928 private:
2929   G1CollectedHeap* _g1h;
2930   size_t _live_bytes;
2931   HeapRegion *_hr;
2932   VerifyOption _vo;
2933 public:
2934   // _vo == UsePrevMarking -> use "prev" marking information,
2935   // _vo == UseNextMarking -> use "next" marking information,
2936   // _vo == UseMarkWord    -> use mark word from object header.
2937   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2938     : _live_bytes(0), _hr(hr), _vo(vo) {
2939     _g1h = G1CollectedHeap::heap();
2940   }
2941   void do_object(oop o) {
2942     VerifyLivenessOopClosure isLive(_g1h, _vo);
2943     assert(o != NULL, "Huh?");
2944     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2945       // If the object is alive according to the mark word,
2946       // then verify that the marking information agrees.
2947       // Note we can't verify the contra-positive of the
2948       // above: if the object is dead (according to the mark
2949       // word), it may not be marked, or may have been marked
2950       // but has since became dead, or may have been allocated
2951       // since the last marking.
2952       if (_vo == VerifyOption_G1UseMarkWord) {
2953         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2954       }
2955 
2956       o->oop_iterate_no_header(&isLive);
2957       if (!_hr->obj_allocated_since_prev_marking(o)) {
2958         size_t obj_size = o->size();    // Make sure we don't overflow
2959         _live_bytes += (obj_size * HeapWordSize);
2960       }
2961     }
2962   }
2963   size_t live_bytes() { return _live_bytes; }
2964 };
2965 
2966 class PrintObjsInRegionClosure : public ObjectClosure {
2967   HeapRegion *_hr;
2968   G1CollectedHeap *_g1;
2969 public:
2970   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2971     _g1 = G1CollectedHeap::heap();
2972   };
2973 
2974   void do_object(oop o) {
2975     if (o != NULL) {
2976       HeapWord *start = (HeapWord *) o;
2977       size_t word_sz = o->size();
2978       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2979                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2980                           (void*) o, word_sz,
2981                           _g1->isMarkedPrev(o),
2982                           _g1->isMarkedNext(o),
2983                           _hr->obj_allocated_since_prev_marking(o));
2984       HeapWord *end = start + word_sz;
2985       HeapWord *cur;
2986       int *val;
2987       for (cur = start; cur < end; cur++) {
2988         val = (int *) cur;
2989         gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2990       }
2991     }
2992   }
2993 };
2994 
2995 class VerifyRegionClosure: public HeapRegionClosure {
2996 private:
2997   bool             _par;
2998   VerifyOption     _vo;
2999   bool             _failures;
3000 public:
3001   // _vo == UsePrevMarking -> use "prev" marking information,
3002   // _vo == UseNextMarking -> use "next" marking information,
3003   // _vo == UseMarkWord    -> use mark word from object header.
3004   VerifyRegionClosure(bool par, VerifyOption vo)
3005     : _par(par),
3006       _vo(vo),
3007       _failures(false) {}
3008 
3009   bool failures() {
3010     return _failures;
3011   }
3012 
3013   bool doHeapRegion(HeapRegion* r) {
3014     if (!r->is_continues_humongous()) {
3015       bool failures = false;
3016       r->verify(_vo, &failures);
3017       if (failures) {
3018         _failures = true;
3019       } else {
3020         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3021         r->object_iterate(&not_dead_yet_cl);
3022         if (_vo != VerifyOption_G1UseNextMarking) {
3023           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3024             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3025                                    "max_live_bytes "SIZE_FORMAT" "
3026                                    "< calculated "SIZE_FORMAT,
3027                                    r->bottom(), r->end(),
3028                                    r->max_live_bytes(),
3029                                  not_dead_yet_cl.live_bytes());
3030             _failures = true;
3031           }
3032         } else {
3033           // When vo == UseNextMarking we cannot currently do a sanity
3034           // check on the live bytes as the calculation has not been
3035           // finalized yet.
3036         }
3037       }
3038     }
3039     return false; // stop the region iteration if we hit a failure
3040   }
3041 };
3042 
3043 // This is the task used for parallel verification of the heap regions
3044 
3045 class G1ParVerifyTask: public AbstractGangTask {
3046 private:
3047   G1CollectedHeap*  _g1h;
3048   VerifyOption      _vo;
3049   bool              _failures;
3050   HeapRegionClaimer _hrclaimer;
3051 
3052 public:
3053   // _vo == UsePrevMarking -> use "prev" marking information,
3054   // _vo == UseNextMarking -> use "next" marking information,
3055   // _vo == UseMarkWord    -> use mark word from object header.
3056   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3057       AbstractGangTask("Parallel verify task"),
3058       _g1h(g1h),
3059       _vo(vo),
3060       _failures(false),
3061       _hrclaimer(g1h->workers()->active_workers()) {}
3062 
3063   bool failures() {
3064     return _failures;
3065   }
3066 
3067   void work(uint worker_id) {
3068     HandleMark hm;
3069     VerifyRegionClosure blk(true, _vo);
3070     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3071     if (blk.failures()) {
3072       _failures = true;
3073     }
3074   }
3075 };
3076 
3077 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3078   if (SafepointSynchronize::is_at_safepoint()) {
3079     assert(Thread::current()->is_VM_thread(),
3080            "Expected to be executed serially by the VM thread at this point");
3081 
3082     if (!silent) { gclog_or_tty->print("Roots "); }
3083     VerifyRootsClosure rootsCl(vo);
3084     VerifyKlassClosure klassCl(this, &rootsCl);
3085     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3086 
3087     // We apply the relevant closures to all the oops in the
3088     // system dictionary, class loader data graph, the string table
3089     // and the nmethods in the code cache.
3090     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3091     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3092 
3093     {
3094       G1RootProcessor root_processor(this);
3095       root_processor.process_all_roots(&rootsCl,
3096                                        &cldCl,
3097                                        &blobsCl);
3098     }
3099 
3100     bool failures = rootsCl.failures() || codeRootsCl.failures();
3101 
3102     if (vo != VerifyOption_G1UseMarkWord) {
3103       // If we're verifying during a full GC then the region sets
3104       // will have been torn down at the start of the GC. Therefore
3105       // verifying the region sets will fail. So we only verify
3106       // the region sets when not in a full GC.
3107       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3108       verify_region_sets();
3109     }
3110 
3111     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3112     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3113 
3114       G1ParVerifyTask task(this, vo);
3115       assert(UseDynamicNumberOfGCThreads ||
3116         workers()->active_workers() == workers()->total_workers(),
3117         "If not dynamic should be using all the workers");
3118       int n_workers = workers()->active_workers();
3119       set_par_threads(n_workers);
3120       workers()->run_task(&task);
3121       set_par_threads(0);
3122       if (task.failures()) {
3123         failures = true;
3124       }
3125 
3126     } else {
3127       VerifyRegionClosure blk(false, vo);
3128       heap_region_iterate(&blk);
3129       if (blk.failures()) {
3130         failures = true;
3131       }
3132     }
3133 
3134     if (G1StringDedup::is_enabled()) {
3135       if (!silent) gclog_or_tty->print("StrDedup ");
3136       G1StringDedup::verify();
3137     }
3138 
3139     if (failures) {
3140       gclog_or_tty->print_cr("Heap:");
3141       // It helps to have the per-region information in the output to
3142       // help us track down what went wrong. This is why we call
3143       // print_extended_on() instead of print_on().
3144       print_extended_on(gclog_or_tty);
3145       gclog_or_tty->cr();
3146 #ifndef PRODUCT
3147       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3148         concurrent_mark()->print_reachable("at-verification-failure",
3149                                            vo, false /* all */);
3150       }
3151 #endif
3152       gclog_or_tty->flush();
3153     }
3154     guarantee(!failures, "there should not have been any failures");
3155   } else {
3156     if (!silent) {
3157       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3158       if (G1StringDedup::is_enabled()) {
3159         gclog_or_tty->print(", StrDedup");
3160       }
3161       gclog_or_tty->print(") ");
3162     }
3163   }
3164 }
3165 
3166 void G1CollectedHeap::verify(bool silent) {
3167   verify(silent, VerifyOption_G1UsePrevMarking);
3168 }
3169 
3170 double G1CollectedHeap::verify(bool guard, const char* msg) {
3171   double verify_time_ms = 0.0;
3172 
3173   if (guard && total_collections() >= VerifyGCStartAt) {
3174     double verify_start = os::elapsedTime();
3175     HandleMark hm;  // Discard invalid handles created during verification
3176     prepare_for_verify();
3177     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3178     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3179   }
3180 
3181   return verify_time_ms;
3182 }
3183 
3184 void G1CollectedHeap::verify_before_gc() {
3185   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3186   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3187 }
3188 
3189 void G1CollectedHeap::verify_after_gc() {
3190   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3191   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3192 }
3193 
3194 class PrintRegionClosure: public HeapRegionClosure {
3195   outputStream* _st;
3196 public:
3197   PrintRegionClosure(outputStream* st) : _st(st) {}
3198   bool doHeapRegion(HeapRegion* r) {
3199     r->print_on(_st);
3200     return false;
3201   }
3202 };
3203 
3204 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3205                                        const HeapRegion* hr,
3206                                        const VerifyOption vo) const {
3207   switch (vo) {
3208   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3209   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3210   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3211   default:                            ShouldNotReachHere();
3212   }
3213   return false; // keep some compilers happy
3214 }
3215 
3216 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3217                                        const VerifyOption vo) const {
3218   switch (vo) {
3219   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3220   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3221   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3222   default:                            ShouldNotReachHere();
3223   }
3224   return false; // keep some compilers happy
3225 }
3226 
3227 void G1CollectedHeap::print_on(outputStream* st) const {
3228   st->print(" %-20s", "garbage-first heap");
3229   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3230             capacity()/K, used_unlocked()/K);
3231   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3232             _hrm.reserved().start(),
3233             _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3234             _hrm.reserved().end());
3235   st->cr();
3236   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3237   uint young_regions = _young_list->length();
3238   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3239             (size_t) young_regions * HeapRegion::GrainBytes / K);
3240   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3241   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3242             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3243   st->cr();
3244   MetaspaceAux::print_on(st);
3245 }
3246 
3247 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3248   print_on(st);
3249 
3250   // Print the per-region information.
3251   st->cr();
3252   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3253                "HS=humongous(starts), HC=humongous(continues), "
3254                "CS=collection set, F=free, TS=gc time stamp, "
3255                "PTAMS=previous top-at-mark-start, "
3256                "NTAMS=next top-at-mark-start)");
3257   PrintRegionClosure blk(st);
3258   heap_region_iterate(&blk);
3259 }
3260 
3261 void G1CollectedHeap::print_on_error(outputStream* st) const {
3262   this->CollectedHeap::print_on_error(st);
3263 
3264   if (_cm != NULL) {
3265     st->cr();
3266     _cm->print_on_error(st);
3267   }
3268 }
3269 
3270 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3271   workers()->print_worker_threads_on(st);
3272   _cmThread->print_on(st);
3273   st->cr();
3274   _cm->print_worker_threads_on(st);
3275   _cg1r->print_worker_threads_on(st);
3276   if (G1StringDedup::is_enabled()) {
3277     G1StringDedup::print_worker_threads_on(st);
3278   }
3279 }
3280 
3281 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3282   workers()->threads_do(tc);
3283   tc->do_thread(_cmThread);
3284   _cg1r->threads_do(tc);
3285   if (G1StringDedup::is_enabled()) {
3286     G1StringDedup::threads_do(tc);
3287   }
3288 }
3289 
3290 void G1CollectedHeap::print_tracing_info() const {
3291   // We'll overload this to mean "trace GC pause statistics."
3292   if (TraceYoungGenTime || TraceOldGenTime) {
3293     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3294     // to that.
3295     g1_policy()->print_tracing_info();
3296   }
3297   if (G1SummarizeRSetStats) {
3298     g1_rem_set()->print_summary_info();
3299   }
3300   if (G1SummarizeConcMark) {
3301     concurrent_mark()->print_summary_info();
3302   }
3303   g1_policy()->print_yg_surv_rate_info();
3304 }
3305 
3306 #ifndef PRODUCT
3307 // Helpful for debugging RSet issues.
3308 
3309 class PrintRSetsClosure : public HeapRegionClosure {
3310 private:
3311   const char* _msg;
3312   size_t _occupied_sum;
3313 
3314 public:
3315   bool doHeapRegion(HeapRegion* r) {
3316     HeapRegionRemSet* hrrs = r->rem_set();
3317     size_t occupied = hrrs->occupied();
3318     _occupied_sum += occupied;
3319 
3320     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3321                            HR_FORMAT_PARAMS(r));
3322     if (occupied == 0) {
3323       gclog_or_tty->print_cr("  RSet is empty");
3324     } else {
3325       hrrs->print();
3326     }
3327     gclog_or_tty->print_cr("----------");
3328     return false;
3329   }
3330 
3331   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3332     gclog_or_tty->cr();
3333     gclog_or_tty->print_cr("========================================");
3334     gclog_or_tty->print_cr("%s", msg);
3335     gclog_or_tty->cr();
3336   }
3337 
3338   ~PrintRSetsClosure() {
3339     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3340     gclog_or_tty->print_cr("========================================");
3341     gclog_or_tty->cr();
3342   }
3343 };
3344 
3345 void G1CollectedHeap::print_cset_rsets() {
3346   PrintRSetsClosure cl("Printing CSet RSets");
3347   collection_set_iterate(&cl);
3348 }
3349 
3350 void G1CollectedHeap::print_all_rsets() {
3351   PrintRSetsClosure cl("Printing All RSets");;
3352   heap_region_iterate(&cl);
3353 }
3354 #endif // PRODUCT
3355 
3356 G1CollectedHeap* G1CollectedHeap::heap() {
3357   return _g1h;
3358 }
3359 
3360 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3361   // always_do_update_barrier = false;
3362   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3363   // Fill TLAB's and such
3364   accumulate_statistics_all_tlabs();
3365   ensure_parsability(true);
3366 
3367   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3368       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3369     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3370   }
3371 }
3372 
3373 void G1CollectedHeap::gc_epilogue(bool full) {
3374 
3375   if (G1SummarizeRSetStats &&
3376       (G1SummarizeRSetStatsPeriod > 0) &&
3377       // we are at the end of the GC. Total collections has already been increased.
3378       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3379     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3380   }
3381 
3382   // FIXME: what is this about?
3383   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3384   // is set.
3385   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3386                         "derived pointer present"));
3387   // always_do_update_barrier = true;
3388 
3389   resize_all_tlabs();
3390   allocation_context_stats().update(full);
3391 
3392   // We have just completed a GC. Update the soft reference
3393   // policy with the new heap occupancy
3394   Universe::update_heap_info_at_gc();
3395 }
3396 
3397 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3398                                                uint gc_count_before,
3399                                                bool* succeeded,
3400                                                GCCause::Cause gc_cause) {
3401   assert_heap_not_locked_and_not_at_safepoint();
3402   g1_policy()->record_stop_world_start();
3403   VM_G1IncCollectionPause op(gc_count_before,
3404                              word_size,
3405                              false, /* should_initiate_conc_mark */
3406                              g1_policy()->max_pause_time_ms(),
3407                              gc_cause);
3408 
3409   op.set_allocation_context(AllocationContext::current());
3410   VMThread::execute(&op);
3411 
3412   HeapWord* result = op.result();
3413   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3414   assert(result == NULL || ret_succeeded,
3415          "the result should be NULL if the VM did not succeed");
3416   *succeeded = ret_succeeded;
3417 
3418   assert_heap_not_locked();
3419   return result;
3420 }
3421 
3422 void
3423 G1CollectedHeap::doConcurrentMark() {
3424   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3425   if (!_cmThread->in_progress()) {
3426     _cmThread->set_started();
3427     CGC_lock->notify();
3428   }
3429 }
3430 
3431 size_t G1CollectedHeap::pending_card_num() {
3432   size_t extra_cards = 0;
3433   JavaThread *curr = Threads::first();
3434   while (curr != NULL) {
3435     DirtyCardQueue& dcq = curr->dirty_card_queue();
3436     extra_cards += dcq.size();
3437     curr = curr->next();
3438   }
3439   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3440   size_t buffer_size = dcqs.buffer_size();
3441   size_t buffer_num = dcqs.completed_buffers_num();
3442 
3443   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3444   // in bytes - not the number of 'entries'. We need to convert
3445   // into a number of cards.
3446   return (buffer_size * buffer_num + extra_cards) / oopSize;
3447 }
3448 
3449 size_t G1CollectedHeap::cards_scanned() {
3450   return g1_rem_set()->cardsScanned();
3451 }
3452 
3453 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3454   HeapRegion* region = region_at(index);
3455   assert(region->is_starts_humongous(), "Must start a humongous object");
3456   return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3457 }
3458 
3459 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3460  private:
3461   size_t _total_humongous;
3462   size_t _candidate_humongous;
3463 
3464   DirtyCardQueue _dcq;
3465 
3466   bool humongous_region_is_candidate(uint index) {
3467     HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3468     assert(region->is_starts_humongous(), "Must start a humongous object");
3469     HeapRegionRemSet* const rset = region->rem_set();
3470     bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3471     return !oop(region->bottom())->is_objArray() &&
3472            ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3473             (!allow_stale_refs && rset->is_empty()));
3474   }
3475 
3476  public:
3477   RegisterHumongousWithInCSetFastTestClosure()
3478   : _total_humongous(0),
3479     _candidate_humongous(0),
3480     _dcq(&JavaThread::dirty_card_queue_set()) {
3481   }
3482 
3483   virtual bool doHeapRegion(HeapRegion* r) {
3484     if (!r->is_starts_humongous()) {
3485       return false;
3486     }
3487     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3488 
3489     uint region_idx = r->hrm_index();
3490     bool is_candidate = humongous_region_is_candidate(region_idx);
3491     // Is_candidate already filters out humongous object with large remembered sets.
3492     // If we have a humongous object with a few remembered sets, we simply flush these
3493     // remembered set entries into the DCQS. That will result in automatic
3494     // re-evaluation of their remembered set entries during the following evacuation
3495     // phase.
3496     if (is_candidate) {
3497       if (!r->rem_set()->is_empty()) {
3498         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3499                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3500         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3501         HeapRegionRemSetIterator hrrs(r->rem_set());
3502         size_t card_index;
3503         while (hrrs.has_next(card_index)) {
3504           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3505           // The remembered set might contain references to already freed
3506           // regions. Filter out such entries to avoid failing card table
3507           // verification.
3508           if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3509             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3510               *card_ptr = CardTableModRefBS::dirty_card_val();
3511               _dcq.enqueue(card_ptr);
3512             }
3513           }
3514         }
3515         r->rem_set()->clear_locked();
3516       }
3517       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3518       g1h->register_humongous_region_with_cset(region_idx);
3519       _candidate_humongous++;
3520     }
3521     _total_humongous++;
3522 
3523     return false;
3524   }
3525 
3526   size_t total_humongous() const { return _total_humongous; }
3527   size_t candidate_humongous() const { return _candidate_humongous; }
3528 
3529   void flush_rem_set_entries() { _dcq.flush(); }
3530 };
3531 
3532 void G1CollectedHeap::register_humongous_regions_with_cset() {
3533   if (!G1EagerReclaimHumongousObjects) {
3534     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3535     return;
3536   }
3537   double time = os::elapsed_counter();
3538 
3539   RegisterHumongousWithInCSetFastTestClosure cl;
3540   heap_region_iterate(&cl);
3541 
3542   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3543   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3544                                                                   cl.total_humongous(),
3545                                                                   cl.candidate_humongous());
3546   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3547 
3548   if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3549     clear_humongous_is_live_table();
3550   }
3551 
3552   // Finally flush all remembered set entries to re-check into the global DCQS.
3553   cl.flush_rem_set_entries();
3554 }
3555 
3556 void
3557 G1CollectedHeap::setup_surviving_young_words() {
3558   assert(_surviving_young_words == NULL, "pre-condition");
3559   uint array_length = g1_policy()->young_cset_region_length();
3560   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3561   if (_surviving_young_words == NULL) {
3562     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3563                           "Not enough space for young surv words summary.");
3564   }
3565   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3566 #ifdef ASSERT
3567   for (uint i = 0;  i < array_length; ++i) {
3568     assert( _surviving_young_words[i] == 0, "memset above" );
3569   }
3570 #endif // !ASSERT
3571 }
3572 
3573 void
3574 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3575   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3576   uint array_length = g1_policy()->young_cset_region_length();
3577   for (uint i = 0; i < array_length; ++i) {
3578     _surviving_young_words[i] += surv_young_words[i];
3579   }
3580 }
3581 
3582 void
3583 G1CollectedHeap::cleanup_surviving_young_words() {
3584   guarantee( _surviving_young_words != NULL, "pre-condition" );
3585   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3586   _surviving_young_words = NULL;
3587 }
3588 
3589 #ifdef ASSERT
3590 class VerifyCSetClosure: public HeapRegionClosure {
3591 public:
3592   bool doHeapRegion(HeapRegion* hr) {
3593     // Here we check that the CSet region's RSet is ready for parallel
3594     // iteration. The fields that we'll verify are only manipulated
3595     // when the region is part of a CSet and is collected. Afterwards,
3596     // we reset these fields when we clear the region's RSet (when the
3597     // region is freed) so they are ready when the region is
3598     // re-allocated. The only exception to this is if there's an
3599     // evacuation failure and instead of freeing the region we leave
3600     // it in the heap. In that case, we reset these fields during
3601     // evacuation failure handling.
3602     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3603 
3604     // Here's a good place to add any other checks we'd like to
3605     // perform on CSet regions.
3606     return false;
3607   }
3608 };
3609 #endif // ASSERT
3610 
3611 #if TASKQUEUE_STATS
3612 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3613   st->print_raw_cr("GC Task Stats");
3614   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3615   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3616 }
3617 
3618 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3619   print_taskqueue_stats_hdr(st);
3620 
3621   TaskQueueStats totals;
3622   const int n = workers()->total_workers();
3623   for (int i = 0; i < n; ++i) {
3624     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3625     totals += task_queue(i)->stats;
3626   }
3627   st->print_raw("tot "); totals.print(st); st->cr();
3628 
3629   DEBUG_ONLY(totals.verify());
3630 }
3631 
3632 void G1CollectedHeap::reset_taskqueue_stats() {
3633   const int n = workers()->total_workers();
3634   for (int i = 0; i < n; ++i) {
3635     task_queue(i)->stats.reset();
3636   }
3637 }
3638 #endif // TASKQUEUE_STATS
3639 
3640 void G1CollectedHeap::log_gc_header() {
3641   if (!G1Log::fine()) {
3642     return;
3643   }
3644 
3645   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3646 
3647   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3648     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3649     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3650 
3651   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3652 }
3653 
3654 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3655   if (!G1Log::fine()) {
3656     return;
3657   }
3658 
3659   if (G1Log::finer()) {
3660     if (evacuation_failed()) {
3661       gclog_or_tty->print(" (to-space exhausted)");
3662     }
3663     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3664     g1_policy()->phase_times()->note_gc_end();
3665     g1_policy()->phase_times()->print(pause_time_sec);
3666     g1_policy()->print_detailed_heap_transition();
3667   } else {
3668     if (evacuation_failed()) {
3669       gclog_or_tty->print("--");
3670     }
3671     g1_policy()->print_heap_transition();
3672     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3673   }
3674   gclog_or_tty->flush();
3675 }
3676 
3677 bool
3678 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3679   assert_at_safepoint(true /* should_be_vm_thread */);
3680   guarantee(!is_gc_active(), "collection is not reentrant");
3681 
3682   if (GC_locker::check_active_before_gc()) {
3683     return false;
3684   }
3685 
3686   _gc_timer_stw->register_gc_start();
3687 
3688   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3689 
3690   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3691   ResourceMark rm;
3692 
3693   print_heap_before_gc();
3694   trace_heap_before_gc(_gc_tracer_stw);
3695 
3696   verify_region_sets_optional();
3697   verify_dirty_young_regions();
3698 
3699   // This call will decide whether this pause is an initial-mark
3700   // pause. If it is, during_initial_mark_pause() will return true
3701   // for the duration of this pause.
3702   g1_policy()->decide_on_conc_mark_initiation();
3703 
3704   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3705   assert(!g1_policy()->during_initial_mark_pause() ||
3706           g1_policy()->gcs_are_young(), "sanity");
3707 
3708   // We also do not allow mixed GCs during marking.
3709   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3710 
3711   // Record whether this pause is an initial mark. When the current
3712   // thread has completed its logging output and it's safe to signal
3713   // the CM thread, the flag's value in the policy has been reset.
3714   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3715 
3716   // Inner scope for scope based logging, timers, and stats collection
3717   {
3718     EvacuationInfo evacuation_info;
3719 
3720     if (g1_policy()->during_initial_mark_pause()) {
3721       // We are about to start a marking cycle, so we increment the
3722       // full collection counter.
3723       increment_old_marking_cycles_started();
3724       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3725     }
3726 
3727     _gc_tracer_stw->report_yc_type(yc_type());
3728 
3729     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3730 
3731     uint active_workers = workers()->active_workers();
3732     double pause_start_sec = os::elapsedTime();
3733     g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3734     log_gc_header();
3735 
3736     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3737     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3738 
3739     // If the secondary_free_list is not empty, append it to the
3740     // free_list. No need to wait for the cleanup operation to finish;
3741     // the region allocation code will check the secondary_free_list
3742     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3743     // set, skip this step so that the region allocation code has to
3744     // get entries from the secondary_free_list.
3745     if (!G1StressConcRegionFreeing) {
3746       append_secondary_free_list_if_not_empty_with_lock();
3747     }
3748 
3749     assert(check_young_list_well_formed(), "young list should be well formed");
3750 
3751     // Don't dynamically change the number of GC threads this early.  A value of
3752     // 0 is used to indicate serial work.  When parallel work is done,
3753     // it will be set.
3754 
3755     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3756       IsGCActiveMark x;
3757 
3758       gc_prologue(false);
3759       increment_total_collections(false /* full gc */);
3760       increment_gc_time_stamp();
3761 
3762       verify_before_gc();
3763 
3764       check_bitmaps("GC Start");
3765 
3766       COMPILER2_PRESENT(DerivedPointerTable::clear());
3767 
3768       // Please see comment in g1CollectedHeap.hpp and
3769       // G1CollectedHeap::ref_processing_init() to see how
3770       // reference processing currently works in G1.
3771 
3772       // Enable discovery in the STW reference processor
3773       ref_processor_stw()->enable_discovery();
3774 
3775       {
3776         // We want to temporarily turn off discovery by the
3777         // CM ref processor, if necessary, and turn it back on
3778         // on again later if we do. Using a scoped
3779         // NoRefDiscovery object will do this.
3780         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3781 
3782         // Forget the current alloc region (we might even choose it to be part
3783         // of the collection set!).
3784         _allocator->release_mutator_alloc_region();
3785 
3786         // We should call this after we retire the mutator alloc
3787         // region(s) so that all the ALLOC / RETIRE events are generated
3788         // before the start GC event.
3789         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3790 
3791         // This timing is only used by the ergonomics to handle our pause target.
3792         // It is unclear why this should not include the full pause. We will
3793         // investigate this in CR 7178365.
3794         //
3795         // Preserving the old comment here if that helps the investigation:
3796         //
3797         // The elapsed time induced by the start time below deliberately elides
3798         // the possible verification above.
3799         double sample_start_time_sec = os::elapsedTime();
3800 
3801 #if YOUNG_LIST_VERBOSE
3802         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3803         _young_list->print();
3804         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3805 #endif // YOUNG_LIST_VERBOSE
3806 
3807         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3808 
3809         double scan_wait_start = os::elapsedTime();
3810         // We have to wait until the CM threads finish scanning the
3811         // root regions as it's the only way to ensure that all the
3812         // objects on them have been correctly scanned before we start
3813         // moving them during the GC.
3814         bool waited = _cm->root_regions()->wait_until_scan_finished();
3815         double wait_time_ms = 0.0;
3816         if (waited) {
3817           double scan_wait_end = os::elapsedTime();
3818           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3819         }
3820         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3821 
3822 #if YOUNG_LIST_VERBOSE
3823         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3824         _young_list->print();
3825 #endif // YOUNG_LIST_VERBOSE
3826 
3827         if (g1_policy()->during_initial_mark_pause()) {
3828           concurrent_mark()->checkpointRootsInitialPre();
3829         }
3830 
3831 #if YOUNG_LIST_VERBOSE
3832         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3833         _young_list->print();
3834         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3835 #endif // YOUNG_LIST_VERBOSE
3836 
3837         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3838 
3839         register_humongous_regions_with_cset();
3840 
3841         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3842 
3843         _cm->note_start_of_gc();
3844         // We should not verify the per-thread SATB buffers given that
3845         // we have not filtered them yet (we'll do so during the
3846         // GC). We also call this after finalize_cset() to
3847         // ensure that the CSet has been finalized.
3848         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3849                                  true  /* verify_enqueued_buffers */,
3850                                  false /* verify_thread_buffers */,
3851                                  true  /* verify_fingers */);
3852 
3853         if (_hr_printer.is_active()) {
3854           HeapRegion* hr = g1_policy()->collection_set();
3855           while (hr != NULL) {
3856             _hr_printer.cset(hr);
3857             hr = hr->next_in_collection_set();
3858           }
3859         }
3860 
3861 #ifdef ASSERT
3862         VerifyCSetClosure cl;
3863         collection_set_iterate(&cl);
3864 #endif // ASSERT
3865 
3866         setup_surviving_young_words();
3867 
3868         // Initialize the GC alloc regions.
3869         _allocator->init_gc_alloc_regions(evacuation_info);
3870 
3871         // Actually do the work...
3872         evacuate_collection_set(evacuation_info);
3873 
3874         // We do this to mainly verify the per-thread SATB buffers
3875         // (which have been filtered by now) since we didn't verify
3876         // them earlier. No point in re-checking the stacks / enqueued
3877         // buffers given that the CSet has not changed since last time
3878         // we checked.
3879         _cm->verify_no_cset_oops(false /* verify_stacks */,
3880                                  false /* verify_enqueued_buffers */,
3881                                  true  /* verify_thread_buffers */,
3882                                  true  /* verify_fingers */);
3883 
3884         free_collection_set(g1_policy()->collection_set(), evacuation_info);
3885 
3886         eagerly_reclaim_humongous_regions();
3887 
3888         g1_policy()->clear_collection_set();
3889 
3890         cleanup_surviving_young_words();
3891 
3892         // Start a new incremental collection set for the next pause.
3893         g1_policy()->start_incremental_cset_building();
3894 
3895         clear_cset_fast_test();
3896 
3897         _young_list->reset_sampled_info();
3898 
3899         // Don't check the whole heap at this point as the
3900         // GC alloc regions from this pause have been tagged
3901         // as survivors and moved on to the survivor list.
3902         // Survivor regions will fail the !is_young() check.
3903         assert(check_young_list_empty(false /* check_heap */),
3904           "young list should be empty");
3905 
3906 #if YOUNG_LIST_VERBOSE
3907         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3908         _young_list->print();
3909 #endif // YOUNG_LIST_VERBOSE
3910 
3911         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3912                                              _young_list->first_survivor_region(),
3913                                              _young_list->last_survivor_region());
3914 
3915         _young_list->reset_auxilary_lists();
3916 
3917         if (evacuation_failed()) {
3918           _allocator->set_used(recalculate_used());
3919           uint n_queues = MAX2((int)ParallelGCThreads, 1);
3920           for (uint i = 0; i < n_queues; i++) {
3921             if (_evacuation_failed_info_array[i].has_failed()) {
3922               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3923             }
3924           }
3925         } else {
3926           // The "used" of the the collection set have already been subtracted
3927           // when they were freed.  Add in the bytes evacuated.
3928           _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3929         }
3930 
3931         if (g1_policy()->during_initial_mark_pause()) {
3932           // We have to do this before we notify the CM threads that
3933           // they can start working to make sure that all the
3934           // appropriate initialization is done on the CM object.
3935           concurrent_mark()->checkpointRootsInitialPost();
3936           set_marking_started();
3937           // Note that we don't actually trigger the CM thread at
3938           // this point. We do that later when we're sure that
3939           // the current thread has completed its logging output.
3940         }
3941 
3942         allocate_dummy_regions();
3943 
3944 #if YOUNG_LIST_VERBOSE
3945         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3946         _young_list->print();
3947         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3948 #endif // YOUNG_LIST_VERBOSE
3949 
3950         _allocator->init_mutator_alloc_region();
3951 
3952         {
3953           size_t expand_bytes = g1_policy()->expansion_amount();
3954           if (expand_bytes > 0) {
3955             size_t bytes_before = capacity();
3956             // No need for an ergo verbose message here,
3957             // expansion_amount() does this when it returns a value > 0.
3958             if (!expand(expand_bytes)) {
3959               // We failed to expand the heap. Cannot do anything about it.
3960             }
3961           }
3962         }
3963 
3964         // We redo the verification but now wrt to the new CSet which
3965         // has just got initialized after the previous CSet was freed.
3966         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3967                                  true  /* verify_enqueued_buffers */,
3968                                  true  /* verify_thread_buffers */,
3969                                  true  /* verify_fingers */);
3970         _cm->note_end_of_gc();
3971 
3972         // This timing is only used by the ergonomics to handle our pause target.
3973         // It is unclear why this should not include the full pause. We will
3974         // investigate this in CR 7178365.
3975         double sample_end_time_sec = os::elapsedTime();
3976         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3977         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3978 
3979         MemoryService::track_memory_usage();
3980 
3981         // In prepare_for_verify() below we'll need to scan the deferred
3982         // update buffers to bring the RSets up-to-date if
3983         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3984         // the update buffers we'll probably need to scan cards on the
3985         // regions we just allocated to (i.e., the GC alloc
3986         // regions). However, during the last GC we called
3987         // set_saved_mark() on all the GC alloc regions, so card
3988         // scanning might skip the [saved_mark_word()...top()] area of
3989         // those regions (i.e., the area we allocated objects into
3990         // during the last GC). But it shouldn't. Given that
3991         // saved_mark_word() is conditional on whether the GC time stamp
3992         // on the region is current or not, by incrementing the GC time
3993         // stamp here we invalidate all the GC time stamps on all the
3994         // regions and saved_mark_word() will simply return top() for
3995         // all the regions. This is a nicer way of ensuring this rather
3996         // than iterating over the regions and fixing them. In fact, the
3997         // GC time stamp increment here also ensures that
3998         // saved_mark_word() will return top() between pauses, i.e.,
3999         // during concurrent refinement. So we don't need the
4000         // is_gc_active() check to decided which top to use when
4001         // scanning cards (see CR 7039627).
4002         increment_gc_time_stamp();
4003 
4004         verify_after_gc();
4005         check_bitmaps("GC End");
4006 
4007         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4008         ref_processor_stw()->verify_no_references_recorded();
4009 
4010         // CM reference discovery will be re-enabled if necessary.
4011       }
4012 
4013       // We should do this after we potentially expand the heap so
4014       // that all the COMMIT events are generated before the end GC
4015       // event, and after we retire the GC alloc regions so that all
4016       // RETIRE events are generated before the end GC event.
4017       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4018 
4019 #ifdef TRACESPINNING
4020       ParallelTaskTerminator::print_termination_counts();
4021 #endif
4022 
4023       gc_epilogue(false);
4024     }
4025 
4026     // Print the remainder of the GC log output.
4027     log_gc_footer(os::elapsedTime() - pause_start_sec);
4028 
4029     // It is not yet to safe to tell the concurrent mark to
4030     // start as we have some optional output below. We don't want the
4031     // output from the concurrent mark thread interfering with this
4032     // logging output either.
4033 
4034     _hrm.verify_optional();
4035     verify_region_sets_optional();
4036 
4037     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4038     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4039 
4040     print_heap_after_gc();
4041     trace_heap_after_gc(_gc_tracer_stw);
4042 
4043     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4044     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4045     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4046     // before any GC notifications are raised.
4047     g1mm()->update_sizes();
4048 
4049     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4050     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4051     _gc_timer_stw->register_gc_end();
4052     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4053   }
4054   // It should now be safe to tell the concurrent mark thread to start
4055   // without its logging output interfering with the logging output
4056   // that came from the pause.
4057 
4058   if (should_start_conc_mark) {
4059     // CAUTION: after the doConcurrentMark() call below,
4060     // the concurrent marking thread(s) could be running
4061     // concurrently with us. Make sure that anything after
4062     // this point does not assume that we are the only GC thread
4063     // running. Note: of course, the actual marking work will
4064     // not start until the safepoint itself is released in
4065     // SuspendibleThreadSet::desynchronize().
4066     doConcurrentMark();
4067   }
4068 
4069   return true;
4070 }
4071 
4072 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4073   _drain_in_progress = false;
4074   set_evac_failure_closure(cl);
4075   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4076 }
4077 
4078 void G1CollectedHeap::finalize_for_evac_failure() {
4079   assert(_evac_failure_scan_stack != NULL &&
4080          _evac_failure_scan_stack->length() == 0,
4081          "Postcondition");
4082   assert(!_drain_in_progress, "Postcondition");
4083   delete _evac_failure_scan_stack;
4084   _evac_failure_scan_stack = NULL;
4085 }
4086 
4087 void G1CollectedHeap::remove_self_forwarding_pointers() {
4088   double remove_self_forwards_start = os::elapsedTime();
4089 
4090   set_par_threads();
4091   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4092   workers()->run_task(&rsfp_task);
4093   set_par_threads(0);
4094 
4095   // Now restore saved marks, if any.
4096   assert(_objs_with_preserved_marks.size() ==
4097             _preserved_marks_of_objs.size(), "Both or none.");
4098   while (!_objs_with_preserved_marks.is_empty()) {
4099     oop obj = _objs_with_preserved_marks.pop();
4100     markOop m = _preserved_marks_of_objs.pop();
4101     obj->set_mark(m);
4102   }
4103   _objs_with_preserved_marks.clear(true);
4104   _preserved_marks_of_objs.clear(true);
4105 
4106   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4107 }
4108 
4109 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4110   _evac_failure_scan_stack->push(obj);
4111 }
4112 
4113 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4114   assert(_evac_failure_scan_stack != NULL, "precondition");
4115 
4116   while (_evac_failure_scan_stack->length() > 0) {
4117      oop obj = _evac_failure_scan_stack->pop();
4118      _evac_failure_closure->set_region(heap_region_containing(obj));
4119      obj->oop_iterate_backwards(_evac_failure_closure);
4120   }
4121 }
4122 
4123 oop
4124 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4125                                                oop old) {
4126   assert(obj_in_cs(old),
4127          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4128                  (HeapWord*) old));
4129   markOop m = old->mark();
4130   oop forward_ptr = old->forward_to_atomic(old);
4131   if (forward_ptr == NULL) {
4132     // Forward-to-self succeeded.
4133     assert(_par_scan_state != NULL, "par scan state");
4134     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4135     uint queue_num = _par_scan_state->queue_num();
4136 
4137     _evacuation_failed = true;
4138     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4139     if (_evac_failure_closure != cl) {
4140       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4141       assert(!_drain_in_progress,
4142              "Should only be true while someone holds the lock.");
4143       // Set the global evac-failure closure to the current thread's.
4144       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4145       set_evac_failure_closure(cl);
4146       // Now do the common part.
4147       handle_evacuation_failure_common(old, m);
4148       // Reset to NULL.
4149       set_evac_failure_closure(NULL);
4150     } else {
4151       // The lock is already held, and this is recursive.
4152       assert(_drain_in_progress, "This should only be the recursive case.");
4153       handle_evacuation_failure_common(old, m);
4154     }
4155     return old;
4156   } else {
4157     // Forward-to-self failed. Either someone else managed to allocate
4158     // space for this object (old != forward_ptr) or they beat us in
4159     // self-forwarding it (old == forward_ptr).
4160     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4161            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4162                    "should not be in the CSet",
4163                    (HeapWord*) old, (HeapWord*) forward_ptr));
4164     return forward_ptr;
4165   }
4166 }
4167 
4168 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4169   preserve_mark_if_necessary(old, m);
4170 
4171   HeapRegion* r = heap_region_containing(old);
4172   if (!r->evacuation_failed()) {
4173     r->set_evacuation_failed(true);
4174     _hr_printer.evac_failure(r);
4175   }
4176 
4177   push_on_evac_failure_scan_stack(old);
4178 
4179   if (!_drain_in_progress) {
4180     // prevent recursion in copy_to_survivor_space()
4181     _drain_in_progress = true;
4182     drain_evac_failure_scan_stack();
4183     _drain_in_progress = false;
4184   }
4185 }
4186 
4187 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4188   assert(evacuation_failed(), "Oversaving!");
4189   // We want to call the "for_promotion_failure" version only in the
4190   // case of a promotion failure.
4191   if (m->must_be_preserved_for_promotion_failure(obj)) {
4192     _objs_with_preserved_marks.push(obj);
4193     _preserved_marks_of_objs.push(m);
4194   }
4195 }
4196 
4197 void G1ParCopyHelper::mark_object(oop obj) {
4198   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4199 
4200   // We know that the object is not moving so it's safe to read its size.
4201   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4202 }
4203 
4204 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4205   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4206   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4207   assert(from_obj != to_obj, "should not be self-forwarded");
4208 
4209   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4210   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4211 
4212   // The object might be in the process of being copied by another
4213   // worker so we cannot trust that its to-space image is
4214   // well-formed. So we have to read its size from its from-space
4215   // image which we know should not be changing.
4216   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4217 }
4218 
4219 template <class T>
4220 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4221   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4222     _scanned_klass->record_modified_oops();
4223   }
4224 }
4225 
4226 template <G1Barrier barrier, G1Mark do_mark_object>
4227 template <class T>
4228 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4229   T heap_oop = oopDesc::load_heap_oop(p);
4230 
4231   if (oopDesc::is_null(heap_oop)) {
4232     return;
4233   }
4234 
4235   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4236 
4237   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4238 
4239   const InCSetState state = _g1->in_cset_state(obj);
4240   if (state.is_in_cset()) {
4241     oop forwardee;
4242     markOop m = obj->mark();
4243     if (m->is_marked()) {
4244       forwardee = (oop) m->decode_pointer();
4245     } else {
4246       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4247     }
4248     assert(forwardee != NULL, "forwardee should not be NULL");
4249     oopDesc::encode_store_heap_oop(p, forwardee);
4250     if (do_mark_object != G1MarkNone && forwardee != obj) {
4251       // If the object is self-forwarded we don't need to explicitly
4252       // mark it, the evacuation failure protocol will do so.
4253       mark_forwarded_object(obj, forwardee);
4254     }
4255 
4256     if (barrier == G1BarrierKlass) {
4257       do_klass_barrier(p, forwardee);
4258     }
4259   } else {
4260     if (state.is_humongous()) {
4261       _g1->set_humongous_is_live(obj);
4262     }
4263     // The object is not in collection set. If we're a root scanning
4264     // closure during an initial mark pause then attempt to mark the object.
4265     if (do_mark_object == G1MarkFromRoot) {
4266       mark_object(obj);
4267     }
4268   }
4269 
4270   if (barrier == G1BarrierEvac) {
4271     _par_scan_state->update_rs(_from, p, _worker_id);
4272   }
4273 }
4274 
4275 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4276 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4277 
4278 class G1ParEvacuateFollowersClosure : public VoidClosure {
4279 protected:
4280   G1CollectedHeap*              _g1h;
4281   G1ParScanThreadState*         _par_scan_state;
4282   RefToScanQueueSet*            _queues;
4283   ParallelTaskTerminator*       _terminator;
4284 
4285   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4286   RefToScanQueueSet*      queues()         { return _queues; }
4287   ParallelTaskTerminator* terminator()     { return _terminator; }
4288 
4289 public:
4290   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4291                                 G1ParScanThreadState* par_scan_state,
4292                                 RefToScanQueueSet* queues,
4293                                 ParallelTaskTerminator* terminator)
4294     : _g1h(g1h), _par_scan_state(par_scan_state),
4295       _queues(queues), _terminator(terminator) {}
4296 
4297   void do_void();
4298 
4299 private:
4300   inline bool offer_termination();
4301 };
4302 
4303 bool G1ParEvacuateFollowersClosure::offer_termination() {
4304   G1ParScanThreadState* const pss = par_scan_state();
4305   pss->start_term_time();
4306   const bool res = terminator()->offer_termination();
4307   pss->end_term_time();
4308   return res;
4309 }
4310 
4311 void G1ParEvacuateFollowersClosure::do_void() {
4312   G1ParScanThreadState* const pss = par_scan_state();
4313   pss->trim_queue();
4314   do {
4315     pss->steal_and_trim_queue(queues());
4316   } while (!offer_termination());
4317 }
4318 
4319 class G1KlassScanClosure : public KlassClosure {
4320  G1ParCopyHelper* _closure;
4321  bool             _process_only_dirty;
4322  int              _count;
4323  public:
4324   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4325       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4326   void do_klass(Klass* klass) {
4327     // If the klass has not been dirtied we know that there's
4328     // no references into  the young gen and we can skip it.
4329    if (!_process_only_dirty || klass->has_modified_oops()) {
4330       // Clean the klass since we're going to scavenge all the metadata.
4331       klass->clear_modified_oops();
4332 
4333       // Tell the closure that this klass is the Klass to scavenge
4334       // and is the one to dirty if oops are left pointing into the young gen.
4335       _closure->set_scanned_klass(klass);
4336 
4337       klass->oops_do(_closure);
4338 
4339       _closure->set_scanned_klass(NULL);
4340     }
4341     _count++;
4342   }
4343 };
4344 
4345 class G1ParTask : public AbstractGangTask {
4346 protected:
4347   G1CollectedHeap*       _g1h;
4348   RefToScanQueueSet      *_queues;
4349   G1RootProcessor*       _root_processor;
4350   ParallelTaskTerminator _terminator;
4351   uint _n_workers;
4352 
4353   Mutex _stats_lock;
4354   Mutex* stats_lock() { return &_stats_lock; }
4355 
4356 public:
4357   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4358     : AbstractGangTask("G1 collection"),
4359       _g1h(g1h),
4360       _queues(task_queues),
4361       _root_processor(root_processor),
4362       _terminator(0, _queues),
4363       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4364   {}
4365 
4366   RefToScanQueueSet* queues() { return _queues; }
4367 
4368   RefToScanQueue *work_queue(int i) {
4369     return queues()->queue(i);
4370   }
4371 
4372   ParallelTaskTerminator* terminator() { return &_terminator; }
4373 
4374   virtual void set_for_termination(int active_workers) {
4375     _root_processor->set_num_workers(active_workers);
4376     terminator()->reset_for_reuse(active_workers);
4377     _n_workers = active_workers;
4378   }
4379 
4380   // Helps out with CLD processing.
4381   //
4382   // During InitialMark we need to:
4383   // 1) Scavenge all CLDs for the young GC.
4384   // 2) Mark all objects directly reachable from strong CLDs.
4385   template <G1Mark do_mark_object>
4386   class G1CLDClosure : public CLDClosure {
4387     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4388     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4389     G1KlassScanClosure                                _klass_in_cld_closure;
4390     bool                                              _claim;
4391 
4392    public:
4393     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4394                  bool only_young, bool claim)
4395         : _oop_closure(oop_closure),
4396           _oop_in_klass_closure(oop_closure->g1(),
4397                                 oop_closure->pss(),
4398                                 oop_closure->rp()),
4399           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4400           _claim(claim) {
4401 
4402     }
4403 
4404     void do_cld(ClassLoaderData* cld) {
4405       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4406     }
4407   };
4408 
4409   void work(uint worker_id) {
4410     if (worker_id >= _n_workers) return;  // no work needed this round
4411 
4412     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4413 
4414     {
4415       ResourceMark rm;
4416       HandleMark   hm;
4417 
4418       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4419 
4420       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4421       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4422 
4423       pss.set_evac_failure_closure(&evac_failure_cl);
4424 
4425       bool only_young = _g1h->g1_policy()->gcs_are_young();
4426 
4427       // Non-IM young GC.
4428       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4429       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4430                                                                                only_young, // Only process dirty klasses.
4431                                                                                false);     // No need to claim CLDs.
4432       // IM young GC.
4433       //    Strong roots closures.
4434       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4435       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4436                                                                                false, // Process all klasses.
4437                                                                                true); // Need to claim CLDs.
4438       //    Weak roots closures.
4439       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4440       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4441                                                                                     false, // Process all klasses.
4442                                                                                     true); // Need to claim CLDs.
4443 
4444       OopClosure* strong_root_cl;
4445       OopClosure* weak_root_cl;
4446       CLDClosure* strong_cld_cl;
4447       CLDClosure* weak_cld_cl;
4448 
4449       bool trace_metadata = false;
4450 
4451       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4452         // We also need to mark copied objects.
4453         strong_root_cl = &scan_mark_root_cl;
4454         strong_cld_cl  = &scan_mark_cld_cl;
4455         if (ClassUnloadingWithConcurrentMark) {
4456           weak_root_cl = &scan_mark_weak_root_cl;
4457           weak_cld_cl  = &scan_mark_weak_cld_cl;
4458           trace_metadata = true;
4459         } else {
4460           weak_root_cl = &scan_mark_root_cl;
4461           weak_cld_cl  = &scan_mark_cld_cl;
4462         }
4463       } else {
4464         strong_root_cl = &scan_only_root_cl;
4465         weak_root_cl   = &scan_only_root_cl;
4466         strong_cld_cl  = &scan_only_cld_cl;
4467         weak_cld_cl    = &scan_only_cld_cl;
4468       }
4469 
4470       pss.start_strong_roots();
4471 
4472       _root_processor->evacuate_roots(strong_root_cl,
4473                                       weak_root_cl,
4474                                       strong_cld_cl,
4475                                       weak_cld_cl,
4476                                       trace_metadata,
4477                                       worker_id);
4478 
4479       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4480       _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4481                                             weak_root_cl,
4482                                             worker_id);
4483       pss.end_strong_roots();
4484 
4485       {
4486         double start = os::elapsedTime();
4487         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4488         evac.do_void();
4489         double elapsed_sec = os::elapsedTime() - start;
4490         double term_sec = pss.term_time();
4491         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4492         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4493         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4494       }
4495       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4496       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4497 
4498       if (PrintTerminationStats) {
4499         MutexLocker x(stats_lock());
4500         pss.print_termination_stats(worker_id);
4501       }
4502 
4503       assert(pss.queue_is_empty(), "should be empty");
4504 
4505       // Close the inner scope so that the ResourceMark and HandleMark
4506       // destructors are executed here and are included as part of the
4507       // "GC Worker Time".
4508     }
4509     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4510   }
4511 };
4512 
4513 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4514 private:
4515   BoolObjectClosure* _is_alive;
4516   int _initial_string_table_size;
4517   int _initial_symbol_table_size;
4518 
4519   bool  _process_strings;
4520   int _strings_processed;
4521   int _strings_removed;
4522 
4523   bool  _process_symbols;
4524   int _symbols_processed;
4525   int _symbols_removed;
4526 
4527 public:
4528   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4529     AbstractGangTask("String/Symbol Unlinking"),
4530     _is_alive(is_alive),
4531     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4532     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4533 
4534     _initial_string_table_size = StringTable::the_table()->table_size();
4535     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4536     if (process_strings) {
4537       StringTable::clear_parallel_claimed_index();
4538     }
4539     if (process_symbols) {
4540       SymbolTable::clear_parallel_claimed_index();
4541     }
4542   }
4543 
4544   ~G1StringSymbolTableUnlinkTask() {
4545     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4546               err_msg("claim value %d after unlink less than initial string table size %d",
4547                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4548     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4549               err_msg("claim value %d after unlink less than initial symbol table size %d",
4550                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4551 
4552     if (G1TraceStringSymbolTableScrubbing) {
4553       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4554                              "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4555                              "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4556                              strings_processed(), strings_removed(),
4557                              symbols_processed(), symbols_removed());
4558     }
4559   }
4560 
4561   void work(uint worker_id) {
4562     int strings_processed = 0;
4563     int strings_removed = 0;
4564     int symbols_processed = 0;
4565     int symbols_removed = 0;
4566     if (_process_strings) {
4567       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4568       Atomic::add(strings_processed, &_strings_processed);
4569       Atomic::add(strings_removed, &_strings_removed);
4570     }
4571     if (_process_symbols) {
4572       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4573       Atomic::add(symbols_processed, &_symbols_processed);
4574       Atomic::add(symbols_removed, &_symbols_removed);
4575     }
4576   }
4577 
4578   size_t strings_processed() const { return (size_t)_strings_processed; }
4579   size_t strings_removed()   const { return (size_t)_strings_removed; }
4580 
4581   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4582   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4583 };
4584 
4585 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4586 private:
4587   static Monitor* _lock;
4588 
4589   BoolObjectClosure* const _is_alive;
4590   const bool               _unloading_occurred;
4591   const uint               _num_workers;
4592 
4593   // Variables used to claim nmethods.
4594   nmethod* _first_nmethod;
4595   volatile nmethod* _claimed_nmethod;
4596 
4597   // The list of nmethods that need to be processed by the second pass.
4598   volatile nmethod* _postponed_list;
4599   volatile uint     _num_entered_barrier;
4600 
4601  public:
4602   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4603       _is_alive(is_alive),
4604       _unloading_occurred(unloading_occurred),
4605       _num_workers(num_workers),
4606       _first_nmethod(NULL),
4607       _claimed_nmethod(NULL),
4608       _postponed_list(NULL),
4609       _num_entered_barrier(0)
4610   {
4611     nmethod::increase_unloading_clock();
4612     // Get first alive nmethod
4613     NMethodIterator iter = NMethodIterator();
4614     if(iter.next_alive()) {
4615       _first_nmethod = iter.method();
4616     }
4617     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4618   }
4619 
4620   ~G1CodeCacheUnloadingTask() {
4621     CodeCache::verify_clean_inline_caches();
4622 
4623     CodeCache::set_needs_cache_clean(false);
4624     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4625 
4626     CodeCache::verify_icholder_relocations();
4627   }
4628 
4629  private:
4630   void add_to_postponed_list(nmethod* nm) {
4631       nmethod* old;
4632       do {
4633         old = (nmethod*)_postponed_list;
4634         nm->set_unloading_next(old);
4635       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4636   }
4637 
4638   void clean_nmethod(nmethod* nm) {
4639     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4640 
4641     if (postponed) {
4642       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4643       add_to_postponed_list(nm);
4644     }
4645 
4646     // Mark that this thread has been cleaned/unloaded.
4647     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4648     nm->set_unloading_clock(nmethod::global_unloading_clock());
4649   }
4650 
4651   void clean_nmethod_postponed(nmethod* nm) {
4652     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4653   }
4654 
4655   static const int MaxClaimNmethods = 16;
4656 
4657   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4658     nmethod* first;
4659     NMethodIterator last;
4660 
4661     do {
4662       *num_claimed_nmethods = 0;
4663 
4664       first = (nmethod*)_claimed_nmethod;
4665       last = NMethodIterator(first);
4666 
4667       if (first != NULL) {
4668 
4669         for (int i = 0; i < MaxClaimNmethods; i++) {
4670           if (!last.next_alive()) {
4671             break;
4672           }
4673           claimed_nmethods[i] = last.method();
4674           (*num_claimed_nmethods)++;
4675         }
4676       }
4677 
4678     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4679   }
4680 
4681   nmethod* claim_postponed_nmethod() {
4682     nmethod* claim;
4683     nmethod* next;
4684 
4685     do {
4686       claim = (nmethod*)_postponed_list;
4687       if (claim == NULL) {
4688         return NULL;
4689       }
4690 
4691       next = claim->unloading_next();
4692 
4693     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4694 
4695     return claim;
4696   }
4697 
4698  public:
4699   // Mark that we're done with the first pass of nmethod cleaning.
4700   void barrier_mark(uint worker_id) {
4701     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4702     _num_entered_barrier++;
4703     if (_num_entered_barrier == _num_workers) {
4704       ml.notify_all();
4705     }
4706   }
4707 
4708   // See if we have to wait for the other workers to
4709   // finish their first-pass nmethod cleaning work.
4710   void barrier_wait(uint worker_id) {
4711     if (_num_entered_barrier < _num_workers) {
4712       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4713       while (_num_entered_barrier < _num_workers) {
4714           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4715       }
4716     }
4717   }
4718 
4719   // Cleaning and unloading of nmethods. Some work has to be postponed
4720   // to the second pass, when we know which nmethods survive.
4721   void work_first_pass(uint worker_id) {
4722     // The first nmethods is claimed by the first worker.
4723     if (worker_id == 0 && _first_nmethod != NULL) {
4724       clean_nmethod(_first_nmethod);
4725       _first_nmethod = NULL;
4726     }
4727 
4728     int num_claimed_nmethods;
4729     nmethod* claimed_nmethods[MaxClaimNmethods];
4730 
4731     while (true) {
4732       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4733 
4734       if (num_claimed_nmethods == 0) {
4735         break;
4736       }
4737 
4738       for (int i = 0; i < num_claimed_nmethods; i++) {
4739         clean_nmethod(claimed_nmethods[i]);
4740       }
4741     }
4742   }
4743 
4744   void work_second_pass(uint worker_id) {
4745     nmethod* nm;
4746     // Take care of postponed nmethods.
4747     while ((nm = claim_postponed_nmethod()) != NULL) {
4748       clean_nmethod_postponed(nm);
4749     }
4750   }
4751 };
4752 
4753 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4754 
4755 class G1KlassCleaningTask : public StackObj {
4756   BoolObjectClosure*                      _is_alive;
4757   volatile jint                           _clean_klass_tree_claimed;
4758   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4759 
4760  public:
4761   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4762       _is_alive(is_alive),
4763       _clean_klass_tree_claimed(0),
4764       _klass_iterator() {
4765   }
4766 
4767  private:
4768   bool claim_clean_klass_tree_task() {
4769     if (_clean_klass_tree_claimed) {
4770       return false;
4771     }
4772 
4773     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4774   }
4775 
4776   InstanceKlass* claim_next_klass() {
4777     Klass* klass;
4778     do {
4779       klass =_klass_iterator.next_klass();
4780     } while (klass != NULL && !klass->oop_is_instance());
4781 
4782     return (InstanceKlass*)klass;
4783   }
4784 
4785 public:
4786 
4787   void clean_klass(InstanceKlass* ik) {
4788     ik->clean_implementors_list(_is_alive);
4789     ik->clean_method_data(_is_alive);
4790 
4791     // G1 specific cleanup work that has
4792     // been moved here to be done in parallel.
4793     ik->clean_dependent_nmethods();
4794   }
4795 
4796   void work() {
4797     ResourceMark rm;
4798 
4799     // One worker will clean the subklass/sibling klass tree.
4800     if (claim_clean_klass_tree_task()) {
4801       Klass::clean_subklass_tree(_is_alive);
4802     }
4803 
4804     // All workers will help cleaning the classes,
4805     InstanceKlass* klass;
4806     while ((klass = claim_next_klass()) != NULL) {
4807       clean_klass(klass);
4808     }
4809   }
4810 };
4811 
4812 // To minimize the remark pause times, the tasks below are done in parallel.
4813 class G1ParallelCleaningTask : public AbstractGangTask {
4814 private:
4815   G1StringSymbolTableUnlinkTask _string_symbol_task;
4816   G1CodeCacheUnloadingTask      _code_cache_task;
4817   G1KlassCleaningTask           _klass_cleaning_task;
4818 
4819 public:
4820   // The constructor is run in the VMThread.
4821   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4822       AbstractGangTask("Parallel Cleaning"),
4823       _string_symbol_task(is_alive, process_strings, process_symbols),
4824       _code_cache_task(num_workers, is_alive, unloading_occurred),
4825       _klass_cleaning_task(is_alive) {
4826   }
4827 
4828   // The parallel work done by all worker threads.
4829   void work(uint worker_id) {
4830     // Do first pass of code cache cleaning.
4831     _code_cache_task.work_first_pass(worker_id);
4832 
4833     // Let the threads mark that the first pass is done.
4834     _code_cache_task.barrier_mark(worker_id);
4835 
4836     // Clean the Strings and Symbols.
4837     _string_symbol_task.work(worker_id);
4838 
4839     // Wait for all workers to finish the first code cache cleaning pass.
4840     _code_cache_task.barrier_wait(worker_id);
4841 
4842     // Do the second code cache cleaning work, which realize on
4843     // the liveness information gathered during the first pass.
4844     _code_cache_task.work_second_pass(worker_id);
4845 
4846     // Clean all klasses that were not unloaded.
4847     _klass_cleaning_task.work();
4848   }
4849 };
4850 
4851 
4852 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4853                                         bool process_strings,
4854                                         bool process_symbols,
4855                                         bool class_unloading_occurred) {
4856   uint n_workers = workers()->active_workers();
4857 
4858   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4859                                         n_workers, class_unloading_occurred);
4860   set_par_threads(n_workers);
4861   workers()->run_task(&g1_unlink_task);
4862   set_par_threads(0);
4863 }
4864 
4865 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4866                                                      bool process_strings, bool process_symbols) {
4867   {
4868     uint n_workers = _g1h->workers()->active_workers();
4869     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4870     set_par_threads(n_workers);
4871     workers()->run_task(&g1_unlink_task);
4872     set_par_threads(0);
4873   }
4874 
4875   if (G1StringDedup::is_enabled()) {
4876     G1StringDedup::unlink(is_alive);
4877   }
4878 }
4879 
4880 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4881  private:
4882   DirtyCardQueueSet* _queue;
4883  public:
4884   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4885 
4886   virtual void work(uint worker_id) {
4887     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4888     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4889 
4890     RedirtyLoggedCardTableEntryClosure cl;
4891     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4892 
4893     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4894   }
4895 };
4896 
4897 void G1CollectedHeap::redirty_logged_cards() {
4898   double redirty_logged_cards_start = os::elapsedTime();
4899 
4900   uint n_workers = _g1h->workers()->active_workers();
4901 
4902   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4903   dirty_card_queue_set().reset_for_par_iteration();
4904   set_par_threads(n_workers);
4905   workers()->run_task(&redirty_task);
4906   set_par_threads(0);
4907 
4908   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4909   dcq.merge_bufferlists(&dirty_card_queue_set());
4910   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4911 
4912   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4913 }
4914 
4915 // Weak Reference Processing support
4916 
4917 // An always "is_alive" closure that is used to preserve referents.
4918 // If the object is non-null then it's alive.  Used in the preservation
4919 // of referent objects that are pointed to by reference objects
4920 // discovered by the CM ref processor.
4921 class G1AlwaysAliveClosure: public BoolObjectClosure {
4922   G1CollectedHeap* _g1;
4923 public:
4924   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4925   bool do_object_b(oop p) {
4926     if (p != NULL) {
4927       return true;
4928     }
4929     return false;
4930   }
4931 };
4932 
4933 bool G1STWIsAliveClosure::do_object_b(oop p) {
4934   // An object is reachable if it is outside the collection set,
4935   // or is inside and copied.
4936   return !_g1->obj_in_cs(p) || p->is_forwarded();
4937 }
4938 
4939 // Non Copying Keep Alive closure
4940 class G1KeepAliveClosure: public OopClosure {
4941   G1CollectedHeap* _g1;
4942 public:
4943   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4944   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4945   void do_oop(oop* p) {
4946     oop obj = *p;
4947     assert(obj != NULL, "the caller should have filtered out NULL values");
4948 
4949     const InCSetState cset_state = _g1->in_cset_state(obj);
4950     if (!cset_state.is_in_cset_or_humongous()) {
4951       return;
4952     }
4953     if (cset_state.is_in_cset()) {
4954       assert( obj->is_forwarded(), "invariant" );
4955       *p = obj->forwardee();
4956     } else {
4957       assert(!obj->is_forwarded(), "invariant" );
4958       assert(cset_state.is_humongous(),
4959              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4960       _g1->set_humongous_is_live(obj);
4961     }
4962   }
4963 };
4964 
4965 // Copying Keep Alive closure - can be called from both
4966 // serial and parallel code as long as different worker
4967 // threads utilize different G1ParScanThreadState instances
4968 // and different queues.
4969 
4970 class G1CopyingKeepAliveClosure: public OopClosure {
4971   G1CollectedHeap*         _g1h;
4972   OopClosure*              _copy_non_heap_obj_cl;
4973   G1ParScanThreadState*    _par_scan_state;
4974 
4975 public:
4976   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4977                             OopClosure* non_heap_obj_cl,
4978                             G1ParScanThreadState* pss):
4979     _g1h(g1h),
4980     _copy_non_heap_obj_cl(non_heap_obj_cl),
4981     _par_scan_state(pss)
4982   {}
4983 
4984   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4985   virtual void do_oop(      oop* p) { do_oop_work(p); }
4986 
4987   template <class T> void do_oop_work(T* p) {
4988     oop obj = oopDesc::load_decode_heap_oop(p);
4989 
4990     if (_g1h->is_in_cset_or_humongous(obj)) {
4991       // If the referent object has been forwarded (either copied
4992       // to a new location or to itself in the event of an
4993       // evacuation failure) then we need to update the reference
4994       // field and, if both reference and referent are in the G1
4995       // heap, update the RSet for the referent.
4996       //
4997       // If the referent has not been forwarded then we have to keep
4998       // it alive by policy. Therefore we have copy the referent.
4999       //
5000       // If the reference field is in the G1 heap then we can push
5001       // on the PSS queue. When the queue is drained (after each
5002       // phase of reference processing) the object and it's followers
5003       // will be copied, the reference field set to point to the
5004       // new location, and the RSet updated. Otherwise we need to
5005       // use the the non-heap or metadata closures directly to copy
5006       // the referent object and update the pointer, while avoiding
5007       // updating the RSet.
5008 
5009       if (_g1h->is_in_g1_reserved(p)) {
5010         _par_scan_state->push_on_queue(p);
5011       } else {
5012         assert(!Metaspace::contains((const void*)p),
5013                err_msg("Unexpectedly found a pointer from metadata: "
5014                               PTR_FORMAT, p));
5015         _copy_non_heap_obj_cl->do_oop(p);
5016       }
5017     }
5018   }
5019 };
5020 
5021 // Serial drain queue closure. Called as the 'complete_gc'
5022 // closure for each discovered list in some of the
5023 // reference processing phases.
5024 
5025 class G1STWDrainQueueClosure: public VoidClosure {
5026 protected:
5027   G1CollectedHeap* _g1h;
5028   G1ParScanThreadState* _par_scan_state;
5029 
5030   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5031 
5032 public:
5033   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5034     _g1h(g1h),
5035     _par_scan_state(pss)
5036   { }
5037 
5038   void do_void() {
5039     G1ParScanThreadState* const pss = par_scan_state();
5040     pss->trim_queue();
5041   }
5042 };
5043 
5044 // Parallel Reference Processing closures
5045 
5046 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5047 // processing during G1 evacuation pauses.
5048 
5049 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5050 private:
5051   G1CollectedHeap*   _g1h;
5052   RefToScanQueueSet* _queues;
5053   FlexibleWorkGang*  _workers;
5054   int                _active_workers;
5055 
5056 public:
5057   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5058                         FlexibleWorkGang* workers,
5059                         RefToScanQueueSet *task_queues,
5060                         int n_workers) :
5061     _g1h(g1h),
5062     _queues(task_queues),
5063     _workers(workers),
5064     _active_workers(n_workers)
5065   {
5066     assert(n_workers > 0, "shouldn't call this otherwise");
5067   }
5068 
5069   // Executes the given task using concurrent marking worker threads.
5070   virtual void execute(ProcessTask& task);
5071   virtual void execute(EnqueueTask& task);
5072 };
5073 
5074 // Gang task for possibly parallel reference processing
5075 
5076 class G1STWRefProcTaskProxy: public AbstractGangTask {
5077   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5078   ProcessTask&     _proc_task;
5079   G1CollectedHeap* _g1h;
5080   RefToScanQueueSet *_task_queues;
5081   ParallelTaskTerminator* _terminator;
5082 
5083 public:
5084   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5085                      G1CollectedHeap* g1h,
5086                      RefToScanQueueSet *task_queues,
5087                      ParallelTaskTerminator* terminator) :
5088     AbstractGangTask("Process reference objects in parallel"),
5089     _proc_task(proc_task),
5090     _g1h(g1h),
5091     _task_queues(task_queues),
5092     _terminator(terminator)
5093   {}
5094 
5095   virtual void work(uint worker_id) {
5096     // The reference processing task executed by a single worker.
5097     ResourceMark rm;
5098     HandleMark   hm;
5099 
5100     G1STWIsAliveClosure is_alive(_g1h);
5101 
5102     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5103     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5104 
5105     pss.set_evac_failure_closure(&evac_failure_cl);
5106 
5107     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5108 
5109     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5110 
5111     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5112 
5113     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5114       // We also need to mark copied objects.
5115       copy_non_heap_cl = &copy_mark_non_heap_cl;
5116     }
5117 
5118     // Keep alive closure.
5119     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5120 
5121     // Complete GC closure
5122     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5123 
5124     // Call the reference processing task's work routine.
5125     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5126 
5127     // Note we cannot assert that the refs array is empty here as not all
5128     // of the processing tasks (specifically phase2 - pp2_work) execute
5129     // the complete_gc closure (which ordinarily would drain the queue) so
5130     // the queue may not be empty.
5131   }
5132 };
5133 
5134 // Driver routine for parallel reference processing.
5135 // Creates an instance of the ref processing gang
5136 // task and has the worker threads execute it.
5137 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5138   assert(_workers != NULL, "Need parallel worker threads.");
5139 
5140   ParallelTaskTerminator terminator(_active_workers, _queues);
5141   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5142 
5143   _g1h->set_par_threads(_active_workers);
5144   _workers->run_task(&proc_task_proxy);
5145   _g1h->set_par_threads(0);
5146 }
5147 
5148 // Gang task for parallel reference enqueueing.
5149 
5150 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5151   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5152   EnqueueTask& _enq_task;
5153 
5154 public:
5155   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5156     AbstractGangTask("Enqueue reference objects in parallel"),
5157     _enq_task(enq_task)
5158   { }
5159 
5160   virtual void work(uint worker_id) {
5161     _enq_task.work(worker_id);
5162   }
5163 };
5164 
5165 // Driver routine for parallel reference enqueueing.
5166 // Creates an instance of the ref enqueueing gang
5167 // task and has the worker threads execute it.
5168 
5169 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5170   assert(_workers != NULL, "Need parallel worker threads.");
5171 
5172   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5173 
5174   _g1h->set_par_threads(_active_workers);
5175   _workers->run_task(&enq_task_proxy);
5176   _g1h->set_par_threads(0);
5177 }
5178 
5179 // End of weak reference support closures
5180 
5181 // Abstract task used to preserve (i.e. copy) any referent objects
5182 // that are in the collection set and are pointed to by reference
5183 // objects discovered by the CM ref processor.
5184 
5185 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5186 protected:
5187   G1CollectedHeap* _g1h;
5188   RefToScanQueueSet      *_queues;
5189   ParallelTaskTerminator _terminator;
5190   uint _n_workers;
5191 
5192 public:
5193   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5194     AbstractGangTask("ParPreserveCMReferents"),
5195     _g1h(g1h),
5196     _queues(task_queues),
5197     _terminator(workers, _queues),
5198     _n_workers(workers)
5199   { }
5200 
5201   void work(uint worker_id) {
5202     ResourceMark rm;
5203     HandleMark   hm;
5204 
5205     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5206     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5207 
5208     pss.set_evac_failure_closure(&evac_failure_cl);
5209 
5210     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5211 
5212     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5213 
5214     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5215 
5216     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5217 
5218     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5219       // We also need to mark copied objects.
5220       copy_non_heap_cl = &copy_mark_non_heap_cl;
5221     }
5222 
5223     // Is alive closure
5224     G1AlwaysAliveClosure always_alive(_g1h);
5225 
5226     // Copying keep alive closure. Applied to referent objects that need
5227     // to be copied.
5228     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5229 
5230     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5231 
5232     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5233     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5234 
5235     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5236     // So this must be true - but assert just in case someone decides to
5237     // change the worker ids.
5238     assert(worker_id < limit, "sanity");
5239     assert(!rp->discovery_is_atomic(), "check this code");
5240 
5241     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5242     for (uint idx = worker_id; idx < limit; idx += stride) {
5243       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5244 
5245       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5246       while (iter.has_next()) {
5247         // Since discovery is not atomic for the CM ref processor, we
5248         // can see some null referent objects.
5249         iter.load_ptrs(DEBUG_ONLY(true));
5250         oop ref = iter.obj();
5251 
5252         // This will filter nulls.
5253         if (iter.is_referent_alive()) {
5254           iter.make_referent_alive();
5255         }
5256         iter.move_to_next();
5257       }
5258     }
5259 
5260     // Drain the queue - which may cause stealing
5261     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5262     drain_queue.do_void();
5263     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5264     assert(pss.queue_is_empty(), "should be");
5265   }
5266 };
5267 
5268 // Weak Reference processing during an evacuation pause (part 1).
5269 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5270   double ref_proc_start = os::elapsedTime();
5271 
5272   ReferenceProcessor* rp = _ref_processor_stw;
5273   assert(rp->discovery_enabled(), "should have been enabled");
5274 
5275   // Any reference objects, in the collection set, that were 'discovered'
5276   // by the CM ref processor should have already been copied (either by
5277   // applying the external root copy closure to the discovered lists, or
5278   // by following an RSet entry).
5279   //
5280   // But some of the referents, that are in the collection set, that these
5281   // reference objects point to may not have been copied: the STW ref
5282   // processor would have seen that the reference object had already
5283   // been 'discovered' and would have skipped discovering the reference,
5284   // but would not have treated the reference object as a regular oop.
5285   // As a result the copy closure would not have been applied to the
5286   // referent object.
5287   //
5288   // We need to explicitly copy these referent objects - the references
5289   // will be processed at the end of remarking.
5290   //
5291   // We also need to do this copying before we process the reference
5292   // objects discovered by the STW ref processor in case one of these
5293   // referents points to another object which is also referenced by an
5294   // object discovered by the STW ref processor.
5295 
5296   assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5297 
5298   set_par_threads(no_of_gc_workers);
5299   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5300                                                  no_of_gc_workers,
5301                                                  _task_queues);
5302 
5303   workers()->run_task(&keep_cm_referents);
5304 
5305   set_par_threads(0);
5306 
5307   // Closure to test whether a referent is alive.
5308   G1STWIsAliveClosure is_alive(this);
5309 
5310   // Even when parallel reference processing is enabled, the processing
5311   // of JNI refs is serial and performed serially by the current thread
5312   // rather than by a worker. The following PSS will be used for processing
5313   // JNI refs.
5314 
5315   // Use only a single queue for this PSS.
5316   G1ParScanThreadState            pss(this, 0, NULL);
5317 
5318   // We do not embed a reference processor in the copying/scanning
5319   // closures while we're actually processing the discovered
5320   // reference objects.
5321   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5322 
5323   pss.set_evac_failure_closure(&evac_failure_cl);
5324 
5325   assert(pss.queue_is_empty(), "pre-condition");
5326 
5327   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5328 
5329   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5330 
5331   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5332 
5333   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5334     // We also need to mark copied objects.
5335     copy_non_heap_cl = &copy_mark_non_heap_cl;
5336   }
5337 
5338   // Keep alive closure.
5339   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5340 
5341   // Serial Complete GC closure
5342   G1STWDrainQueueClosure drain_queue(this, &pss);
5343 
5344   // Setup the soft refs policy...
5345   rp->setup_policy(false);
5346 
5347   ReferenceProcessorStats stats;
5348   if (!rp->processing_is_mt()) {
5349     // Serial reference processing...
5350     stats = rp->process_discovered_references(&is_alive,
5351                                               &keep_alive,
5352                                               &drain_queue,
5353                                               NULL,
5354                                               _gc_timer_stw,
5355                                               _gc_tracer_stw->gc_id());
5356   } else {
5357     // Parallel reference processing
5358     assert(rp->num_q() == no_of_gc_workers, "sanity");
5359     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5360 
5361     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5362     stats = rp->process_discovered_references(&is_alive,
5363                                               &keep_alive,
5364                                               &drain_queue,
5365                                               &par_task_executor,
5366                                               _gc_timer_stw,
5367                                               _gc_tracer_stw->gc_id());
5368   }
5369 
5370   _gc_tracer_stw->report_gc_reference_stats(stats);
5371 
5372   // We have completed copying any necessary live referent objects.
5373   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5374 
5375   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5376   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5377 }
5378 
5379 // Weak Reference processing during an evacuation pause (part 2).
5380 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5381   double ref_enq_start = os::elapsedTime();
5382 
5383   ReferenceProcessor* rp = _ref_processor_stw;
5384   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5385 
5386   // Now enqueue any remaining on the discovered lists on to
5387   // the pending list.
5388   if (!rp->processing_is_mt()) {
5389     // Serial reference processing...
5390     rp->enqueue_discovered_references();
5391   } else {
5392     // Parallel reference enqueueing
5393 
5394     assert(no_of_gc_workers == workers()->active_workers(),
5395            "Need to reset active workers");
5396     assert(rp->num_q() == no_of_gc_workers, "sanity");
5397     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5398 
5399     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5400     rp->enqueue_discovered_references(&par_task_executor);
5401   }
5402 
5403   rp->verify_no_references_recorded();
5404   assert(!rp->discovery_enabled(), "should have been disabled");
5405 
5406   // FIXME
5407   // CM's reference processing also cleans up the string and symbol tables.
5408   // Should we do that here also? We could, but it is a serial operation
5409   // and could significantly increase the pause time.
5410 
5411   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5412   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5413 }
5414 
5415 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5416   _expand_heap_after_alloc_failure = true;
5417   _evacuation_failed = false;
5418 
5419   // Should G1EvacuationFailureALot be in effect for this GC?
5420   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5421 
5422   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5423 
5424   // Disable the hot card cache.
5425   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5426   hot_card_cache->reset_hot_cache_claimed_index();
5427   hot_card_cache->set_use_cache(false);
5428 
5429   uint n_workers;
5430   n_workers =
5431     AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5432                                    workers()->active_workers(),
5433                                    Threads::number_of_non_daemon_threads());
5434   assert(UseDynamicNumberOfGCThreads ||
5435          n_workers == workers()->total_workers(),
5436          "If not dynamic should be using all the  workers");
5437   workers()->set_active_workers(n_workers);
5438   set_par_threads(n_workers);
5439 
5440 
5441   init_for_evac_failure(NULL);
5442 
5443   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5444   double start_par_time_sec = os::elapsedTime();
5445   double end_par_time_sec;
5446 
5447   {
5448     G1RootProcessor root_processor(this);
5449     G1ParTask g1_par_task(this, _task_queues, &root_processor);
5450     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5451     if (g1_policy()->during_initial_mark_pause()) {
5452       ClassLoaderDataGraph::clear_claimed_marks();
5453     }
5454 
5455      // The individual threads will set their evac-failure closures.
5456      if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5457      // These tasks use ShareHeap::_process_strong_tasks
5458      assert(UseDynamicNumberOfGCThreads ||
5459             workers()->active_workers() == workers()->total_workers(),
5460             "If not dynamic should be using all the  workers");
5461     workers()->run_task(&g1_par_task);
5462     end_par_time_sec = os::elapsedTime();
5463 
5464     // Closing the inner scope will execute the destructor
5465     // for the G1RootProcessor object. We record the current
5466     // elapsed time before closing the scope so that time
5467     // taken for the destructor is NOT included in the
5468     // reported parallel time.
5469   }
5470 
5471   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5472 
5473   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5474   phase_times->record_par_time(par_time_ms);
5475 
5476   double code_root_fixup_time_ms =
5477         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5478   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5479 
5480   set_par_threads(0);
5481 
5482   // Process any discovered reference objects - we have
5483   // to do this _before_ we retire the GC alloc regions
5484   // as we may have to copy some 'reachable' referent
5485   // objects (and their reachable sub-graphs) that were
5486   // not copied during the pause.
5487   process_discovered_references(n_workers);
5488 
5489   if (G1StringDedup::is_enabled()) {
5490     double fixup_start = os::elapsedTime();
5491 
5492     G1STWIsAliveClosure is_alive(this);
5493     G1KeepAliveClosure keep_alive(this);
5494     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5495 
5496     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5497     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5498   }
5499 
5500   _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5501   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5502 
5503   // Reset and re-enable the hot card cache.
5504   // Note the counts for the cards in the regions in the
5505   // collection set are reset when the collection set is freed.
5506   hot_card_cache->reset_hot_cache();
5507   hot_card_cache->set_use_cache(true);
5508 
5509   purge_code_root_memory();
5510 
5511   finalize_for_evac_failure();
5512 
5513   if (evacuation_failed()) {
5514     remove_self_forwarding_pointers();
5515 
5516     // Reset the G1EvacuationFailureALot counters and flags
5517     // Note: the values are reset only when an actual
5518     // evacuation failure occurs.
5519     NOT_PRODUCT(reset_evacuation_should_fail();)
5520   }
5521 
5522   // Enqueue any remaining references remaining on the STW
5523   // reference processor's discovered lists. We need to do
5524   // this after the card table is cleaned (and verified) as
5525   // the act of enqueueing entries on to the pending list
5526   // will log these updates (and dirty their associated
5527   // cards). We need these updates logged to update any
5528   // RSets.
5529   enqueue_discovered_references(n_workers);
5530 
5531   redirty_logged_cards();
5532   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5533 }
5534 
5535 void G1CollectedHeap::free_region(HeapRegion* hr,
5536                                   FreeRegionList* free_list,
5537                                   bool par,
5538                                   bool locked) {
5539   assert(!hr->is_free(), "the region should not be free");
5540   assert(!hr->is_empty(), "the region should not be empty");
5541   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5542   assert(free_list != NULL, "pre-condition");
5543 
5544   if (G1VerifyBitmaps) {
5545     MemRegion mr(hr->bottom(), hr->end());
5546     concurrent_mark()->clearRangePrevBitmap(mr);
5547   }
5548 
5549   // Clear the card counts for this region.
5550   // Note: we only need to do this if the region is not young
5551   // (since we don't refine cards in young regions).
5552   if (!hr->is_young()) {
5553     _cg1r->hot_card_cache()->reset_card_counts(hr);
5554   }
5555   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5556   free_list->add_ordered(hr);
5557 }
5558 
5559 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5560                                      FreeRegionList* free_list,
5561                                      bool par) {
5562   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5563   assert(free_list != NULL, "pre-condition");
5564 
5565   size_t hr_capacity = hr->capacity();
5566   // We need to read this before we make the region non-humongous,
5567   // otherwise the information will be gone.
5568   uint last_index = hr->last_hc_index();
5569   hr->clear_humongous();
5570   free_region(hr, free_list, par);
5571 
5572   uint i = hr->hrm_index() + 1;
5573   while (i < last_index) {
5574     HeapRegion* curr_hr = region_at(i);
5575     assert(curr_hr->is_continues_humongous(), "invariant");
5576     curr_hr->clear_humongous();
5577     free_region(curr_hr, free_list, par);
5578     i += 1;
5579   }
5580 }
5581 
5582 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5583                                        const HeapRegionSetCount& humongous_regions_removed) {
5584   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5585     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5586     _old_set.bulk_remove(old_regions_removed);
5587     _humongous_set.bulk_remove(humongous_regions_removed);
5588   }
5589 
5590 }
5591 
5592 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5593   assert(list != NULL, "list can't be null");
5594   if (!list->is_empty()) {
5595     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5596     _hrm.insert_list_into_free_list(list);
5597   }
5598 }
5599 
5600 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5601   _allocator->decrease_used(bytes);
5602 }
5603 
5604 class G1ParCleanupCTTask : public AbstractGangTask {
5605   G1SATBCardTableModRefBS* _ct_bs;
5606   G1CollectedHeap* _g1h;
5607   HeapRegion* volatile _su_head;
5608 public:
5609   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5610                      G1CollectedHeap* g1h) :
5611     AbstractGangTask("G1 Par Cleanup CT Task"),
5612     _ct_bs(ct_bs), _g1h(g1h) { }
5613 
5614   void work(uint worker_id) {
5615     HeapRegion* r;
5616     while (r = _g1h->pop_dirty_cards_region()) {
5617       clear_cards(r);
5618     }
5619   }
5620 
5621   void clear_cards(HeapRegion* r) {
5622     // Cards of the survivors should have already been dirtied.
5623     if (!r->is_survivor()) {
5624       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5625     }
5626   }
5627 };
5628 
5629 #ifndef PRODUCT
5630 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5631   G1CollectedHeap* _g1h;
5632   G1SATBCardTableModRefBS* _ct_bs;
5633 public:
5634   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5635     : _g1h(g1h), _ct_bs(ct_bs) { }
5636   virtual bool doHeapRegion(HeapRegion* r) {
5637     if (r->is_survivor()) {
5638       _g1h->verify_dirty_region(r);
5639     } else {
5640       _g1h->verify_not_dirty_region(r);
5641     }
5642     return false;
5643   }
5644 };
5645 
5646 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5647   // All of the region should be clean.
5648   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5649   MemRegion mr(hr->bottom(), hr->end());
5650   ct_bs->verify_not_dirty_region(mr);
5651 }
5652 
5653 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5654   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5655   // dirty allocated blocks as they allocate them. The thread that
5656   // retires each region and replaces it with a new one will do a
5657   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5658   // not dirty that area (one less thing to have to do while holding
5659   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5660   // is dirty.
5661   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5662   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5663   if (hr->is_young()) {
5664     ct_bs->verify_g1_young_region(mr);
5665   } else {
5666     ct_bs->verify_dirty_region(mr);
5667   }
5668 }
5669 
5670 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5671   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5672   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5673     verify_dirty_region(hr);
5674   }
5675 }
5676 
5677 void G1CollectedHeap::verify_dirty_young_regions() {
5678   verify_dirty_young_list(_young_list->first_region());
5679 }
5680 
5681 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5682                                                HeapWord* tams, HeapWord* end) {
5683   guarantee(tams <= end,
5684             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5685   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5686   if (result < end) {
5687     gclog_or_tty->cr();
5688     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5689                            bitmap_name, result);
5690     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5691                            bitmap_name, tams, end);
5692     return false;
5693   }
5694   return true;
5695 }
5696 
5697 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5698   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5699   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5700 
5701   HeapWord* bottom = hr->bottom();
5702   HeapWord* ptams  = hr->prev_top_at_mark_start();
5703   HeapWord* ntams  = hr->next_top_at_mark_start();
5704   HeapWord* end    = hr->end();
5705 
5706   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5707 
5708   bool res_n = true;
5709   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5710   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5711   // if we happen to be in that state.
5712   if (mark_in_progress() || !_cmThread->in_progress()) {
5713     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5714   }
5715   if (!res_p || !res_n) {
5716     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5717                            HR_FORMAT_PARAMS(hr));
5718     gclog_or_tty->print_cr("#### Caller: %s", caller);
5719     return false;
5720   }
5721   return true;
5722 }
5723 
5724 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5725   if (!G1VerifyBitmaps) return;
5726 
5727   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5728 }
5729 
5730 class G1VerifyBitmapClosure : public HeapRegionClosure {
5731 private:
5732   const char* _caller;
5733   G1CollectedHeap* _g1h;
5734   bool _failures;
5735 
5736 public:
5737   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5738     _caller(caller), _g1h(g1h), _failures(false) { }
5739 
5740   bool failures() { return _failures; }
5741 
5742   virtual bool doHeapRegion(HeapRegion* hr) {
5743     if (hr->is_continues_humongous()) return false;
5744 
5745     bool result = _g1h->verify_bitmaps(_caller, hr);
5746     if (!result) {
5747       _failures = true;
5748     }
5749     return false;
5750   }
5751 };
5752 
5753 void G1CollectedHeap::check_bitmaps(const char* caller) {
5754   if (!G1VerifyBitmaps) return;
5755 
5756   G1VerifyBitmapClosure cl(caller, this);
5757   heap_region_iterate(&cl);
5758   guarantee(!cl.failures(), "bitmap verification");
5759 }
5760 
5761 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5762  private:
5763   bool _failures;
5764  public:
5765   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5766 
5767   virtual bool doHeapRegion(HeapRegion* hr) {
5768     uint i = hr->hrm_index();
5769     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5770     if (hr->is_humongous()) {
5771       if (hr->in_collection_set()) {
5772         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5773         _failures = true;
5774         return true;
5775       }
5776       if (cset_state.is_in_cset()) {
5777         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5778         _failures = true;
5779         return true;
5780       }
5781       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5782         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5783         _failures = true;
5784         return true;
5785       }
5786     } else {
5787       if (cset_state.is_humongous()) {
5788         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5789         _failures = true;
5790         return true;
5791       }
5792       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5793         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5794                                hr->in_collection_set(), cset_state.value(), i);
5795         _failures = true;
5796         return true;
5797       }
5798       if (cset_state.is_in_cset()) {
5799         if (hr->is_young() != (cset_state.is_young())) {
5800           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5801                                  hr->is_young(), cset_state.value(), i);
5802           _failures = true;
5803           return true;
5804         }
5805         if (hr->is_old() != (cset_state.is_old())) {
5806           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5807                                  hr->is_old(), cset_state.value(), i);
5808           _failures = true;
5809           return true;
5810         }
5811       }
5812     }
5813     return false;
5814   }
5815 
5816   bool failures() const { return _failures; }
5817 };
5818 
5819 bool G1CollectedHeap::check_cset_fast_test() {
5820   G1CheckCSetFastTableClosure cl;
5821   _hrm.iterate(&cl);
5822   return !cl.failures();
5823 }
5824 #endif // PRODUCT
5825 
5826 void G1CollectedHeap::cleanUpCardTable() {
5827   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5828   double start = os::elapsedTime();
5829 
5830   {
5831     // Iterate over the dirty cards region list.
5832     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5833 
5834     set_par_threads();
5835     workers()->run_task(&cleanup_task);
5836     set_par_threads(0);
5837 #ifndef PRODUCT
5838     if (G1VerifyCTCleanup || VerifyAfterGC) {
5839       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5840       heap_region_iterate(&cleanup_verifier);
5841     }
5842 #endif
5843   }
5844 
5845   double elapsed = os::elapsedTime() - start;
5846   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5847 }
5848 
5849 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5850   size_t pre_used = 0;
5851   FreeRegionList local_free_list("Local List for CSet Freeing");
5852 
5853   double young_time_ms     = 0.0;
5854   double non_young_time_ms = 0.0;
5855 
5856   // Since the collection set is a superset of the the young list,
5857   // all we need to do to clear the young list is clear its
5858   // head and length, and unlink any young regions in the code below
5859   _young_list->clear();
5860 
5861   G1CollectorPolicy* policy = g1_policy();
5862 
5863   double start_sec = os::elapsedTime();
5864   bool non_young = true;
5865 
5866   HeapRegion* cur = cs_head;
5867   int age_bound = -1;
5868   size_t rs_lengths = 0;
5869 
5870   while (cur != NULL) {
5871     assert(!is_on_master_free_list(cur), "sanity");
5872     if (non_young) {
5873       if (cur->is_young()) {
5874         double end_sec = os::elapsedTime();
5875         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5876         non_young_time_ms += elapsed_ms;
5877 
5878         start_sec = os::elapsedTime();
5879         non_young = false;
5880       }
5881     } else {
5882       if (!cur->is_young()) {
5883         double end_sec = os::elapsedTime();
5884         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5885         young_time_ms += elapsed_ms;
5886 
5887         start_sec = os::elapsedTime();
5888         non_young = true;
5889       }
5890     }
5891 
5892     rs_lengths += cur->rem_set()->occupied_locked();
5893 
5894     HeapRegion* next = cur->next_in_collection_set();
5895     assert(cur->in_collection_set(), "bad CS");
5896     cur->set_next_in_collection_set(NULL);
5897     clear_in_cset(cur);
5898 
5899     if (cur->is_young()) {
5900       int index = cur->young_index_in_cset();
5901       assert(index != -1, "invariant");
5902       assert((uint) index < policy->young_cset_region_length(), "invariant");
5903       size_t words_survived = _surviving_young_words[index];
5904       cur->record_surv_words_in_group(words_survived);
5905 
5906       // At this point the we have 'popped' cur from the collection set
5907       // (linked via next_in_collection_set()) but it is still in the
5908       // young list (linked via next_young_region()). Clear the
5909       // _next_young_region field.
5910       cur->set_next_young_region(NULL);
5911     } else {
5912       int index = cur->young_index_in_cset();
5913       assert(index == -1, "invariant");
5914     }
5915 
5916     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5917             (!cur->is_young() && cur->young_index_in_cset() == -1),
5918             "invariant" );
5919 
5920     if (!cur->evacuation_failed()) {
5921       MemRegion used_mr = cur->used_region();
5922 
5923       // And the region is empty.
5924       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5925       pre_used += cur->used();
5926       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5927     } else {
5928       cur->uninstall_surv_rate_group();
5929       if (cur->is_young()) {
5930         cur->set_young_index_in_cset(-1);
5931       }
5932       cur->set_evacuation_failed(false);
5933       // The region is now considered to be old.
5934       cur->set_old();
5935       _old_set.add(cur);
5936       evacuation_info.increment_collectionset_used_after(cur->used());
5937     }
5938     cur = next;
5939   }
5940 
5941   evacuation_info.set_regions_freed(local_free_list.length());
5942   policy->record_max_rs_lengths(rs_lengths);
5943   policy->cset_regions_freed();
5944 
5945   double end_sec = os::elapsedTime();
5946   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5947 
5948   if (non_young) {
5949     non_young_time_ms += elapsed_ms;
5950   } else {
5951     young_time_ms += elapsed_ms;
5952   }
5953 
5954   prepend_to_freelist(&local_free_list);
5955   decrement_summary_bytes(pre_used);
5956   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5957   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5958 }
5959 
5960 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5961  private:
5962   FreeRegionList* _free_region_list;
5963   HeapRegionSet* _proxy_set;
5964   HeapRegionSetCount _humongous_regions_removed;
5965   size_t _freed_bytes;
5966  public:
5967 
5968   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5969     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5970   }
5971 
5972   virtual bool doHeapRegion(HeapRegion* r) {
5973     if (!r->is_starts_humongous()) {
5974       return false;
5975     }
5976 
5977     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5978 
5979     oop obj = (oop)r->bottom();
5980     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5981 
5982     // The following checks whether the humongous object is live are sufficient.
5983     // The main additional check (in addition to having a reference from the roots
5984     // or the young gen) is whether the humongous object has a remembered set entry.
5985     //
5986     // A humongous object cannot be live if there is no remembered set for it
5987     // because:
5988     // - there can be no references from within humongous starts regions referencing
5989     // the object because we never allocate other objects into them.
5990     // (I.e. there are no intra-region references that may be missed by the
5991     // remembered set)
5992     // - as soon there is a remembered set entry to the humongous starts region
5993     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5994     // until the end of a concurrent mark.
5995     //
5996     // It is not required to check whether the object has been found dead by marking
5997     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5998     // all objects allocated during that time are considered live.
5999     // SATB marking is even more conservative than the remembered set.
6000     // So if at this point in the collection there is no remembered set entry,
6001     // nobody has a reference to it.
6002     // At the start of collection we flush all refinement logs, and remembered sets
6003     // are completely up-to-date wrt to references to the humongous object.
6004     //
6005     // Other implementation considerations:
6006     // - never consider object arrays at this time because they would pose
6007     // considerable effort for cleaning up the the remembered sets. This is
6008     // required because stale remembered sets might reference locations that
6009     // are currently allocated into.
6010     uint region_idx = r->hrm_index();
6011     if (g1h->humongous_is_live(region_idx) ||
6012         g1h->humongous_region_is_always_live(region_idx)) {
6013 
6014       if (G1TraceEagerReclaimHumongousObjects) {
6015         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",
6016                                region_idx,
6017                                obj->size()*HeapWordSize,
6018                                r->bottom(),
6019                                r->region_num(),
6020                                r->rem_set()->occupied(),
6021                                r->rem_set()->strong_code_roots_list_length(),
6022                                next_bitmap->isMarked(r->bottom()),
6023                                g1h->humongous_is_live(region_idx),
6024                                obj->is_objArray()
6025                               );
6026       }
6027 
6028       return false;
6029     }
6030 
6031     guarantee(!obj->is_objArray(),
6032               err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6033                       r->bottom()));
6034 
6035     if (G1TraceEagerReclaimHumongousObjects) {
6036       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",
6037                              region_idx,
6038                              obj->size()*HeapWordSize,
6039                              r->bottom(),
6040                              r->region_num(),
6041                              r->rem_set()->occupied(),
6042                              r->rem_set()->strong_code_roots_list_length(),
6043                              next_bitmap->isMarked(r->bottom()),
6044                              g1h->humongous_is_live(region_idx),
6045                              obj->is_objArray()
6046                             );
6047     }
6048     // Need to clear mark bit of the humongous object if already set.
6049     if (next_bitmap->isMarked(r->bottom())) {
6050       next_bitmap->clear(r->bottom());
6051     }
6052     _freed_bytes += r->used();
6053     r->set_containing_set(NULL);
6054     _humongous_regions_removed.increment(1u, r->capacity());
6055     g1h->free_humongous_region(r, _free_region_list, false);
6056 
6057     return false;
6058   }
6059 
6060   HeapRegionSetCount& humongous_free_count() {
6061     return _humongous_regions_removed;
6062   }
6063 
6064   size_t bytes_freed() const {
6065     return _freed_bytes;
6066   }
6067 
6068   size_t humongous_reclaimed() const {
6069     return _humongous_regions_removed.length();
6070   }
6071 };
6072 
6073 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6074   assert_at_safepoint(true);
6075 
6076   if (!G1EagerReclaimHumongousObjects ||
6077       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6078     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6079     return;
6080   }
6081 
6082   double start_time = os::elapsedTime();
6083 
6084   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6085 
6086   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6087   heap_region_iterate(&cl);
6088 
6089   HeapRegionSetCount empty_set;
6090   remove_from_old_sets(empty_set, cl.humongous_free_count());
6091 
6092   G1HRPrinter* hr_printer = _g1h->hr_printer();
6093   if (hr_printer->is_active()) {
6094     FreeRegionListIterator iter(&local_cleanup_list);
6095     while (iter.more_available()) {
6096       HeapRegion* hr = iter.get_next();
6097       hr_printer->cleanup(hr);
6098     }
6099   }
6100 
6101   prepend_to_freelist(&local_cleanup_list);
6102   decrement_summary_bytes(cl.bytes_freed());
6103 
6104   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6105                                                                     cl.humongous_reclaimed());
6106 }
6107 
6108 // This routine is similar to the above but does not record
6109 // any policy statistics or update free lists; we are abandoning
6110 // the current incremental collection set in preparation of a
6111 // full collection. After the full GC we will start to build up
6112 // the incremental collection set again.
6113 // This is only called when we're doing a full collection
6114 // and is immediately followed by the tearing down of the young list.
6115 
6116 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6117   HeapRegion* cur = cs_head;
6118 
6119   while (cur != NULL) {
6120     HeapRegion* next = cur->next_in_collection_set();
6121     assert(cur->in_collection_set(), "bad CS");
6122     cur->set_next_in_collection_set(NULL);
6123     clear_in_cset(cur);
6124     cur->set_young_index_in_cset(-1);
6125     cur = next;
6126   }
6127 }
6128 
6129 void G1CollectedHeap::set_free_regions_coming() {
6130   if (G1ConcRegionFreeingVerbose) {
6131     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6132                            "setting free regions coming");
6133   }
6134 
6135   assert(!free_regions_coming(), "pre-condition");
6136   _free_regions_coming = true;
6137 }
6138 
6139 void G1CollectedHeap::reset_free_regions_coming() {
6140   assert(free_regions_coming(), "pre-condition");
6141 
6142   {
6143     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6144     _free_regions_coming = false;
6145     SecondaryFreeList_lock->notify_all();
6146   }
6147 
6148   if (G1ConcRegionFreeingVerbose) {
6149     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6150                            "reset free regions coming");
6151   }
6152 }
6153 
6154 void G1CollectedHeap::wait_while_free_regions_coming() {
6155   // Most of the time we won't have to wait, so let's do a quick test
6156   // first before we take the lock.
6157   if (!free_regions_coming()) {
6158     return;
6159   }
6160 
6161   if (G1ConcRegionFreeingVerbose) {
6162     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6163                            "waiting for free regions");
6164   }
6165 
6166   {
6167     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6168     while (free_regions_coming()) {
6169       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6170     }
6171   }
6172 
6173   if (G1ConcRegionFreeingVerbose) {
6174     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6175                            "done waiting for free regions");
6176   }
6177 }
6178 
6179 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6180   assert(heap_lock_held_for_gc(),
6181               "the heap lock should already be held by or for this thread");
6182   _young_list->push_region(hr);
6183 }
6184 
6185 class NoYoungRegionsClosure: public HeapRegionClosure {
6186 private:
6187   bool _success;
6188 public:
6189   NoYoungRegionsClosure() : _success(true) { }
6190   bool doHeapRegion(HeapRegion* r) {
6191     if (r->is_young()) {
6192       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6193                              r->bottom(), r->end());
6194       _success = false;
6195     }
6196     return false;
6197   }
6198   bool success() { return _success; }
6199 };
6200 
6201 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6202   bool ret = _young_list->check_list_empty(check_sample);
6203 
6204   if (check_heap) {
6205     NoYoungRegionsClosure closure;
6206     heap_region_iterate(&closure);
6207     ret = ret && closure.success();
6208   }
6209 
6210   return ret;
6211 }
6212 
6213 class TearDownRegionSetsClosure : public HeapRegionClosure {
6214 private:
6215   HeapRegionSet *_old_set;
6216 
6217 public:
6218   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6219 
6220   bool doHeapRegion(HeapRegion* r) {
6221     if (r->is_old()) {
6222       _old_set->remove(r);
6223     } else {
6224       // We ignore free regions, we'll empty the free list afterwards.
6225       // We ignore young regions, we'll empty the young list afterwards.
6226       // We ignore humongous regions, we're not tearing down the
6227       // humongous regions set.
6228       assert(r->is_free() || r->is_young() || r->is_humongous(),
6229              "it cannot be another type");
6230     }
6231     return false;
6232   }
6233 
6234   ~TearDownRegionSetsClosure() {
6235     assert(_old_set->is_empty(), "post-condition");
6236   }
6237 };
6238 
6239 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6240   assert_at_safepoint(true /* should_be_vm_thread */);
6241 
6242   if (!free_list_only) {
6243     TearDownRegionSetsClosure cl(&_old_set);
6244     heap_region_iterate(&cl);
6245 
6246     // Note that emptying the _young_list is postponed and instead done as
6247     // the first step when rebuilding the regions sets again. The reason for
6248     // this is that during a full GC string deduplication needs to know if
6249     // a collected region was young or old when the full GC was initiated.
6250   }
6251   _hrm.remove_all_free_regions();
6252 }
6253 
6254 class RebuildRegionSetsClosure : public HeapRegionClosure {
6255 private:
6256   bool            _free_list_only;
6257   HeapRegionSet*   _old_set;
6258   HeapRegionManager*   _hrm;
6259   size_t          _total_used;
6260 
6261 public:
6262   RebuildRegionSetsClosure(bool free_list_only,
6263                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6264     _free_list_only(free_list_only),
6265     _old_set(old_set), _hrm(hrm), _total_used(0) {
6266     assert(_hrm->num_free_regions() == 0, "pre-condition");
6267     if (!free_list_only) {
6268       assert(_old_set->is_empty(), "pre-condition");
6269     }
6270   }
6271 
6272   bool doHeapRegion(HeapRegion* r) {
6273     if (r->is_continues_humongous()) {
6274       return false;
6275     }
6276 
6277     if (r->is_empty()) {
6278       // Add free regions to the free list
6279       r->set_free();
6280       r->set_allocation_context(AllocationContext::system());
6281       _hrm->insert_into_free_list(r);
6282     } else if (!_free_list_only) {
6283       assert(!r->is_young(), "we should not come across young regions");
6284 
6285       if (r->is_humongous()) {
6286         // We ignore humongous regions, we left the humongous set unchanged
6287       } else {
6288         // Objects that were compacted would have ended up on regions
6289         // that were previously old or free.
6290         assert(r->is_free() || r->is_old(), "invariant");
6291         // We now consider them old, so register as such.
6292         r->set_old();
6293         _old_set->add(r);
6294       }
6295       _total_used += r->used();
6296     }
6297 
6298     return false;
6299   }
6300 
6301   size_t total_used() {
6302     return _total_used;
6303   }
6304 };
6305 
6306 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6307   assert_at_safepoint(true /* should_be_vm_thread */);
6308 
6309   if (!free_list_only) {
6310     _young_list->empty_list();
6311   }
6312 
6313   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6314   heap_region_iterate(&cl);
6315 
6316   if (!free_list_only) {
6317     _allocator->set_used(cl.total_used());
6318   }
6319   assert(_allocator->used_unlocked() == recalculate_used(),
6320          err_msg("inconsistent _allocator->used_unlocked(), "
6321                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6322                  _allocator->used_unlocked(), recalculate_used()));
6323 }
6324 
6325 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6326   _refine_cte_cl->set_concurrent(concurrent);
6327 }
6328 
6329 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6330   HeapRegion* hr = heap_region_containing(p);
6331   return hr->is_in(p);
6332 }
6333 
6334 // Methods for the mutator alloc region
6335 
6336 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6337                                                       bool force) {
6338   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6339   assert(!force || g1_policy()->can_expand_young_list(),
6340          "if force is true we should be able to expand the young list");
6341   bool young_list_full = g1_policy()->is_young_list_full();
6342   if (force || !young_list_full) {
6343     HeapRegion* new_alloc_region = new_region(word_size,
6344                                               false /* is_old */,
6345                                               false /* do_expand */);
6346     if (new_alloc_region != NULL) {
6347       set_region_short_lived_locked(new_alloc_region);
6348       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6349       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6350       return new_alloc_region;
6351     }
6352   }
6353   return NULL;
6354 }
6355 
6356 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6357                                                   size_t allocated_bytes) {
6358   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6359   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6360 
6361   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6362   _allocator->increase_used(allocated_bytes);
6363   _hr_printer.retire(alloc_region);
6364   // We update the eden sizes here, when the region is retired,
6365   // instead of when it's allocated, since this is the point that its
6366   // used space has been recored in _summary_bytes_used.
6367   g1mm()->update_eden_size();
6368 }
6369 
6370 void G1CollectedHeap::set_par_threads() {
6371   // Don't change the number of workers.  Use the value previously set
6372   // in the workgroup.
6373   uint n_workers = workers()->active_workers();
6374   assert(UseDynamicNumberOfGCThreads ||
6375            n_workers == workers()->total_workers(),
6376       "Otherwise should be using the total number of workers");
6377   if (n_workers == 0) {
6378     assert(false, "Should have been set in prior evacuation pause.");
6379     n_workers = ParallelGCThreads;
6380     workers()->set_active_workers(n_workers);
6381   }
6382   set_par_threads(n_workers);
6383 }
6384 
6385 // Methods for the GC alloc regions
6386 
6387 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6388                                                  uint count,
6389                                                  InCSetState dest) {
6390   assert(FreeList_lock->owned_by_self(), "pre-condition");
6391 
6392   if (count < g1_policy()->max_regions(dest)) {
6393     const bool is_survivor = (dest.is_young());
6394     HeapRegion* new_alloc_region = new_region(word_size,
6395                                               !is_survivor,
6396                                               true /* do_expand */);
6397     if (new_alloc_region != NULL) {
6398       // We really only need to do this for old regions given that we
6399       // should never scan survivors. But it doesn't hurt to do it
6400       // for survivors too.
6401       new_alloc_region->record_timestamp();
6402       if (is_survivor) {
6403         new_alloc_region->set_survivor();
6404         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6405         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6406       } else {
6407         new_alloc_region->set_old();
6408         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6409         check_bitmaps("Old Region Allocation", new_alloc_region);
6410       }
6411       bool during_im = g1_policy()->during_initial_mark_pause();
6412       new_alloc_region->note_start_of_copying(during_im);
6413       return new_alloc_region;
6414     }
6415   }
6416   return NULL;
6417 }
6418 
6419 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6420                                              size_t allocated_bytes,
6421                                              InCSetState dest) {
6422   bool during_im = g1_policy()->during_initial_mark_pause();
6423   alloc_region->note_end_of_copying(during_im);
6424   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6425   if (dest.is_young()) {
6426     young_list()->add_survivor_region(alloc_region);
6427   } else {
6428     _old_set.add(alloc_region);
6429   }
6430   _hr_printer.retire(alloc_region);
6431 }
6432 
6433 // Heap region set verification
6434 
6435 class VerifyRegionListsClosure : public HeapRegionClosure {
6436 private:
6437   HeapRegionSet*   _old_set;
6438   HeapRegionSet*   _humongous_set;
6439   HeapRegionManager*   _hrm;
6440 
6441 public:
6442   HeapRegionSetCount _old_count;
6443   HeapRegionSetCount _humongous_count;
6444   HeapRegionSetCount _free_count;
6445 
6446   VerifyRegionListsClosure(HeapRegionSet* old_set,
6447                            HeapRegionSet* humongous_set,
6448                            HeapRegionManager* hrm) :
6449     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6450     _old_count(), _humongous_count(), _free_count(){ }
6451 
6452   bool doHeapRegion(HeapRegion* hr) {
6453     if (hr->is_continues_humongous()) {
6454       return false;
6455     }
6456 
6457     if (hr->is_young()) {
6458       // TODO
6459     } else if (hr->is_starts_humongous()) {
6460       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6461       _humongous_count.increment(1u, hr->capacity());
6462     } else if (hr->is_empty()) {
6463       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6464       _free_count.increment(1u, hr->capacity());
6465     } else if (hr->is_old()) {
6466       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6467       _old_count.increment(1u, hr->capacity());
6468     } else {
6469       ShouldNotReachHere();
6470     }
6471     return false;
6472   }
6473 
6474   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6475     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6476     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6477         old_set->total_capacity_bytes(), _old_count.capacity()));
6478 
6479     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6480     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6481         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6482 
6483     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()));
6484     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6485         free_list->total_capacity_bytes(), _free_count.capacity()));
6486   }
6487 };
6488 
6489 void G1CollectedHeap::verify_region_sets() {
6490   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6491 
6492   // First, check the explicit lists.
6493   _hrm.verify();
6494   {
6495     // Given that a concurrent operation might be adding regions to
6496     // the secondary free list we have to take the lock before
6497     // verifying it.
6498     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6499     _secondary_free_list.verify_list();
6500   }
6501 
6502   // If a concurrent region freeing operation is in progress it will
6503   // be difficult to correctly attributed any free regions we come
6504   // across to the correct free list given that they might belong to
6505   // one of several (free_list, secondary_free_list, any local lists,
6506   // etc.). So, if that's the case we will skip the rest of the
6507   // verification operation. Alternatively, waiting for the concurrent
6508   // operation to complete will have a non-trivial effect on the GC's
6509   // operation (no concurrent operation will last longer than the
6510   // interval between two calls to verification) and it might hide
6511   // any issues that we would like to catch during testing.
6512   if (free_regions_coming()) {
6513     return;
6514   }
6515 
6516   // Make sure we append the secondary_free_list on the free_list so
6517   // that all free regions we will come across can be safely
6518   // attributed to the free_list.
6519   append_secondary_free_list_if_not_empty_with_lock();
6520 
6521   // Finally, make sure that the region accounting in the lists is
6522   // consistent with what we see in the heap.
6523 
6524   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6525   heap_region_iterate(&cl);
6526   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6527 }
6528 
6529 // Optimized nmethod scanning
6530 
6531 class RegisterNMethodOopClosure: public OopClosure {
6532   G1CollectedHeap* _g1h;
6533   nmethod* _nm;
6534 
6535   template <class T> void do_oop_work(T* p) {
6536     T heap_oop = oopDesc::load_heap_oop(p);
6537     if (!oopDesc::is_null(heap_oop)) {
6538       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6539       HeapRegion* hr = _g1h->heap_region_containing(obj);
6540       assert(!hr->is_continues_humongous(),
6541              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6542                      " starting at "HR_FORMAT,
6543                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6544 
6545       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6546       hr->add_strong_code_root_locked(_nm);
6547     }
6548   }
6549 
6550 public:
6551   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6552     _g1h(g1h), _nm(nm) {}
6553 
6554   void do_oop(oop* p)       { do_oop_work(p); }
6555   void do_oop(narrowOop* p) { do_oop_work(p); }
6556 };
6557 
6558 class UnregisterNMethodOopClosure: public OopClosure {
6559   G1CollectedHeap* _g1h;
6560   nmethod* _nm;
6561 
6562   template <class T> void do_oop_work(T* p) {
6563     T heap_oop = oopDesc::load_heap_oop(p);
6564     if (!oopDesc::is_null(heap_oop)) {
6565       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6566       HeapRegion* hr = _g1h->heap_region_containing(obj);
6567       assert(!hr->is_continues_humongous(),
6568              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6569                      " starting at "HR_FORMAT,
6570                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6571 
6572       hr->remove_strong_code_root(_nm);
6573     }
6574   }
6575 
6576 public:
6577   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6578     _g1h(g1h), _nm(nm) {}
6579 
6580   void do_oop(oop* p)       { do_oop_work(p); }
6581   void do_oop(narrowOop* p) { do_oop_work(p); }
6582 };
6583 
6584 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6585   CollectedHeap::register_nmethod(nm);
6586 
6587   guarantee(nm != NULL, "sanity");
6588   RegisterNMethodOopClosure reg_cl(this, nm);
6589   nm->oops_do(&reg_cl);
6590 }
6591 
6592 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6593   CollectedHeap::unregister_nmethod(nm);
6594 
6595   guarantee(nm != NULL, "sanity");
6596   UnregisterNMethodOopClosure reg_cl(this, nm);
6597   nm->oops_do(&reg_cl, true);
6598 }
6599 
6600 void G1CollectedHeap::purge_code_root_memory() {
6601   double purge_start = os::elapsedTime();
6602   G1CodeRootSet::purge();
6603   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6604   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6605 }
6606 
6607 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6608   G1CollectedHeap* _g1h;
6609 
6610 public:
6611   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6612     _g1h(g1h) {}
6613 
6614   void do_code_blob(CodeBlob* cb) {
6615     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6616     if (nm == NULL) {
6617       return;
6618     }
6619 
6620     if (ScavengeRootsInCode) {
6621       _g1h->register_nmethod(nm);
6622     }
6623   }
6624 };
6625 
6626 void G1CollectedHeap::rebuild_strong_code_roots() {
6627   RebuildStrongCodeRootClosure blob_cl(this);
6628   CodeCache::blobs_do(&blob_cl);
6629 }