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