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 #include "utilities/stack.inline.hpp"
  74 
  75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  76 
  77 // turn it on so that the contents of the young list (scan-only /
  78 // to-be-collected) are printed at "strategic" points before / during
  79 // / after the collection --- this is useful for debugging
  80 #define YOUNG_LIST_VERBOSE 0
  81 // CURRENT STATUS
  82 // This file is under construction.  Search for "FIXME".
  83 
  84 // INVARIANTS/NOTES
  85 //
  86 // All allocation activity covered by the G1CollectedHeap interface is
  87 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  88 // and allocate_new_tlab, which are the "entry" points to the
  89 // allocation code from the rest of the JVM.  (Note that this does not
  90 // apply to TLAB allocation, which is not part of this interface: it
  91 // is done by clients of this interface.)
  92 
  93 // Local to this file.
  94 
  95 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  96   bool _concurrent;
  97 public:
  98   RefineCardTableEntryClosure() : _concurrent(true) { }
  99 
 100   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 101     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 102     // This path is executed by the concurrent refine or mutator threads,
 103     // concurrently, and so we do not care if card_ptr contains references
 104     // that point into the collection set.
 105     assert(!oops_into_cset, "should be");
 106 
 107     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 108       // Caller will actually yield.
 109       return false;
 110     }
 111     // Otherwise, we finished successfully; return true.
 112     return true;
 113   }
 114 
 115   void set_concurrent(bool b) { _concurrent = b; }
 116 };
 117 
 118 
 119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 120  private:
 121   size_t _num_processed;
 122 
 123  public:
 124   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 125 
 126   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 127     *card_ptr = CardTableModRefBS::dirty_card_val();
 128     _num_processed++;
 129     return true;
 130   }
 131 
 132   size_t num_processed() const { return _num_processed; }
 133 };
 134 
 135 YoungList::YoungList(G1CollectedHeap* g1h) :
 136     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 137     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 138   guarantee(check_list_empty(false), "just making sure...");
 139 }
 140 
 141 void YoungList::push_region(HeapRegion *hr) {
 142   assert(!hr->is_young(), "should not already be young");
 143   assert(hr->get_next_young_region() == NULL, "cause it should!");
 144 
 145   hr->set_next_young_region(_head);
 146   _head = hr;
 147 
 148   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 149   ++_length;
 150 }
 151 
 152 void YoungList::add_survivor_region(HeapRegion* hr) {
 153   assert(hr->is_survivor(), "should be flagged as survivor region");
 154   assert(hr->get_next_young_region() == NULL, "cause it should!");
 155 
 156   hr->set_next_young_region(_survivor_head);
 157   if (_survivor_head == NULL) {
 158     _survivor_tail = hr;
 159   }
 160   _survivor_head = hr;
 161   ++_survivor_length;
 162 }
 163 
 164 void YoungList::empty_list(HeapRegion* list) {
 165   while (list != NULL) {
 166     HeapRegion* next = list->get_next_young_region();
 167     list->set_next_young_region(NULL);
 168     list->uninstall_surv_rate_group();
 169     // This is called before a Full GC and all the non-empty /
 170     // non-humongous regions at the end of the Full GC will end up as
 171     // old anyway.
 172     list->set_old();
 173     list = next;
 174   }
 175 }
 176 
 177 void YoungList::empty_list() {
 178   assert(check_list_well_formed(), "young list should be well formed");
 179 
 180   empty_list(_head);
 181   _head = NULL;
 182   _length = 0;
 183 
 184   empty_list(_survivor_head);
 185   _survivor_head = NULL;
 186   _survivor_tail = NULL;
 187   _survivor_length = 0;
 188 
 189   _last_sampled_rs_lengths = 0;
 190 
 191   assert(check_list_empty(false), "just making sure...");
 192 }
 193 
 194 bool YoungList::check_list_well_formed() {
 195   bool ret = true;
 196 
 197   uint length = 0;
 198   HeapRegion* curr = _head;
 199   HeapRegion* last = NULL;
 200   while (curr != NULL) {
 201     if (!curr->is_young()) {
 202       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 203                              "incorrectly tagged (y: %d, surv: %d)",
 204                              curr->bottom(), curr->end(),
 205                              curr->is_young(), curr->is_survivor());
 206       ret = false;
 207     }
 208     ++length;
 209     last = curr;
 210     curr = curr->get_next_young_region();
 211   }
 212   ret = ret && (length == _length);
 213 
 214   if (!ret) {
 215     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 216     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 217                            length, _length);
 218   }
 219 
 220   return ret;
 221 }
 222 
 223 bool YoungList::check_list_empty(bool check_sample) {
 224   bool ret = true;
 225 
 226   if (_length != 0) {
 227     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 228                   _length);
 229     ret = false;
 230   }
 231   if (check_sample && _last_sampled_rs_lengths != 0) {
 232     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 233     ret = false;
 234   }
 235   if (_head != NULL) {
 236     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 237     ret = false;
 238   }
 239   if (!ret) {
 240     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 241   }
 242 
 243   return ret;
 244 }
 245 
 246 void
 247 YoungList::rs_length_sampling_init() {
 248   _sampled_rs_lengths = 0;
 249   _curr               = _head;
 250 }
 251 
 252 bool
 253 YoungList::rs_length_sampling_more() {
 254   return _curr != NULL;
 255 }
 256 
 257 void
 258 YoungList::rs_length_sampling_next() {
 259   assert( _curr != NULL, "invariant" );
 260   size_t rs_length = _curr->rem_set()->occupied();
 261 
 262   _sampled_rs_lengths += rs_length;
 263 
 264   // The current region may not yet have been added to the
 265   // incremental collection set (it gets added when it is
 266   // retired as the current allocation region).
 267   if (_curr->in_collection_set()) {
 268     // Update the collection set policy information for this region
 269     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 270   }
 271 
 272   _curr = _curr->get_next_young_region();
 273   if (_curr == NULL) {
 274     _last_sampled_rs_lengths = _sampled_rs_lengths;
 275     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 276   }
 277 }
 278 
 279 void
 280 YoungList::reset_auxilary_lists() {
 281   guarantee( is_empty(), "young list should be empty" );
 282   assert(check_list_well_formed(), "young list should be well formed");
 283 
 284   // Add survivor regions to SurvRateGroup.
 285   _g1h->g1_policy()->note_start_adding_survivor_regions();
 286   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 287 
 288   int young_index_in_cset = 0;
 289   for (HeapRegion* curr = _survivor_head;
 290        curr != NULL;
 291        curr = curr->get_next_young_region()) {
 292     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 293 
 294     // The region is a non-empty survivor so let's add it to
 295     // the incremental collection set for the next evacuation
 296     // pause.
 297     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 298     young_index_in_cset += 1;
 299   }
 300   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 301   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 302 
 303   _head   = _survivor_head;
 304   _length = _survivor_length;
 305   if (_survivor_head != NULL) {
 306     assert(_survivor_tail != NULL, "cause it shouldn't be");
 307     assert(_survivor_length > 0, "invariant");
 308     _survivor_tail->set_next_young_region(NULL);
 309   }
 310 
 311   // Don't clear the survivor list handles until the start of
 312   // the next evacuation pause - we need it in order to re-tag
 313   // the survivor regions from this evacuation pause as 'young'
 314   // at the start of the next.
 315 
 316   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 317 
 318   assert(check_list_well_formed(), "young list should be well formed");
 319 }
 320 
 321 void YoungList::print() {
 322   HeapRegion* lists[] = {_head,   _survivor_head};
 323   const char* names[] = {"YOUNG", "SURVIVOR"};
 324 
 325   for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
 326     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 327     HeapRegion *curr = lists[list];
 328     if (curr == NULL)
 329       gclog_or_tty->print_cr("  empty");
 330     while (curr != NULL) {
 331       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
 332                              HR_FORMAT_PARAMS(curr),
 333                              curr->prev_top_at_mark_start(),
 334                              curr->next_top_at_mark_start(),
 335                              curr->age_in_surv_rate_group_cond());
 336       curr = curr->get_next_young_region();
 337     }
 338   }
 339 
 340   gclog_or_tty->cr();
 341 }
 342 
 343 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 344   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 345 }
 346 
 347 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 348   // The from card cache is not the memory that is actually committed. So we cannot
 349   // take advantage of the zero_filled parameter.
 350   reset_from_card_cache(start_idx, num_regions);
 351 }
 352 
 353 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 354 {
 355   // Claim the right to put the region on the dirty cards region list
 356   // by installing a self pointer.
 357   HeapRegion* next = hr->get_next_dirty_cards_region();
 358   if (next == NULL) {
 359     HeapRegion* res = (HeapRegion*)
 360       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 361                           NULL);
 362     if (res == NULL) {
 363       HeapRegion* head;
 364       do {
 365         // Put the region to the dirty cards region list.
 366         head = _dirty_cards_region_list;
 367         next = (HeapRegion*)
 368           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 369         if (next == head) {
 370           assert(hr->get_next_dirty_cards_region() == hr,
 371                  "hr->get_next_dirty_cards_region() != hr");
 372           if (next == NULL) {
 373             // The last region in the list points to itself.
 374             hr->set_next_dirty_cards_region(hr);
 375           } else {
 376             hr->set_next_dirty_cards_region(next);
 377           }
 378         }
 379       } while (next != head);
 380     }
 381   }
 382 }
 383 
 384 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 385 {
 386   HeapRegion* head;
 387   HeapRegion* hr;
 388   do {
 389     head = _dirty_cards_region_list;
 390     if (head == NULL) {
 391       return NULL;
 392     }
 393     HeapRegion* new_head = head->get_next_dirty_cards_region();
 394     if (head == new_head) {
 395       // The last region.
 396       new_head = NULL;
 397     }
 398     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 399                                           head);
 400   } while (hr != head);
 401   assert(hr != NULL, "invariant");
 402   hr->set_next_dirty_cards_region(NULL);
 403   return hr;
 404 }
 405 
 406 // Returns true if the reference points to an object that
 407 // can move in an incremental collection.
 408 bool G1CollectedHeap::is_scavengable(const void* p) {
 409   HeapRegion* hr = heap_region_containing(p);
 410   return !hr->is_humongous();
 411 }
 412 
 413 // Private class members.
 414 
 415 G1CollectedHeap* G1CollectedHeap::_g1h;
 416 
 417 // Private methods.
 418 
 419 HeapRegion*
 420 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 421   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 422   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 423     if (!_secondary_free_list.is_empty()) {
 424       if (G1ConcRegionFreeingVerbose) {
 425         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 426                                "secondary_free_list has %u entries",
 427                                _secondary_free_list.length());
 428       }
 429       // It looks as if there are free regions available on the
 430       // secondary_free_list. Let's move them to the free_list and try
 431       // again to allocate from it.
 432       append_secondary_free_list();
 433 
 434       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 435              "empty we should have moved at least one entry to the free_list");
 436       HeapRegion* res = _hrm.allocate_free_region(is_old);
 437       if (G1ConcRegionFreeingVerbose) {
 438         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 439                                "allocated "HR_FORMAT" from secondary_free_list",
 440                                HR_FORMAT_PARAMS(res));
 441       }
 442       return res;
 443     }
 444 
 445     // Wait here until we get notified either when (a) there are no
 446     // more free regions coming or (b) some regions have been moved on
 447     // the secondary_free_list.
 448     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 449   }
 450 
 451   if (G1ConcRegionFreeingVerbose) {
 452     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 453                            "could not allocate from secondary_free_list");
 454   }
 455   return NULL;
 456 }
 457 
 458 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 459   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 460          "the only time we use this to allocate a humongous region is "
 461          "when we are allocating a single humongous region");
 462 
 463   HeapRegion* res;
 464   if (G1StressConcRegionFreeing) {
 465     if (!_secondary_free_list.is_empty()) {
 466       if (G1ConcRegionFreeingVerbose) {
 467         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 468                                "forced to look at the secondary_free_list");
 469       }
 470       res = new_region_try_secondary_free_list(is_old);
 471       if (res != NULL) {
 472         return res;
 473       }
 474     }
 475   }
 476 
 477   res = _hrm.allocate_free_region(is_old);
 478 
 479   if (res == NULL) {
 480     if (G1ConcRegionFreeingVerbose) {
 481       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 482                              "res == NULL, trying the secondary_free_list");
 483     }
 484     res = new_region_try_secondary_free_list(is_old);
 485   }
 486   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 487     // Currently, only attempts to allocate GC alloc regions set
 488     // do_expand to true. So, we should only reach here during a
 489     // safepoint. If this assumption changes we might have to
 490     // reconsider the use of _expand_heap_after_alloc_failure.
 491     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 492 
 493     ergo_verbose1(ErgoHeapSizing,
 494                   "attempt heap expansion",
 495                   ergo_format_reason("region allocation request failed")
 496                   ergo_format_byte("allocation request"),
 497                   word_size * HeapWordSize);
 498     if (expand(word_size * HeapWordSize)) {
 499       // Given that expand() succeeded in expanding the heap, and we
 500       // always expand the heap by an amount aligned to the heap
 501       // region size, the free list should in theory not be empty.
 502       // In either case allocate_free_region() will check for NULL.
 503       res = _hrm.allocate_free_region(is_old);
 504     } else {
 505       _expand_heap_after_alloc_failure = false;
 506     }
 507   }
 508   return res;
 509 }
 510 
 511 HeapWord*
 512 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 513                                                            uint num_regions,
 514                                                            size_t word_size,
 515                                                            AllocationContext_t context) {
 516   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 517   assert(is_humongous(word_size), "word_size should be humongous");
 518   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 519 
 520   // Index of last region in the series + 1.
 521   uint last = first + num_regions;
 522 
 523   // We need to initialize the region(s) we just discovered. This is
 524   // a bit tricky given that it can happen concurrently with
 525   // refinement threads refining cards on these regions and
 526   // potentially wanting to refine the BOT as they are scanning
 527   // those cards (this can happen shortly after a cleanup; see CR
 528   // 6991377). So we have to set up the region(s) carefully and in
 529   // a specific order.
 530 
 531   // The word size sum of all the regions we will allocate.
 532   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 533   assert(word_size <= word_size_sum, "sanity");
 534 
 535   // This will be the "starts humongous" region.
 536   HeapRegion* first_hr = region_at(first);
 537   // The header of the new object will be placed at the bottom of
 538   // the first region.
 539   HeapWord* new_obj = first_hr->bottom();
 540   // This will be the new end of the first region in the series that
 541   // should also match the end of the last region in the series.
 542   HeapWord* new_end = new_obj + word_size_sum;
 543   // This will be the new top of the first region that will reflect
 544   // this allocation.
 545   HeapWord* new_top = new_obj + word_size;
 546 
 547   // First, we need to zero the header of the space that we will be
 548   // allocating. When we update top further down, some refinement
 549   // threads might try to scan the region. By zeroing the header we
 550   // ensure that any thread that will try to scan the region will
 551   // come across the zero klass word and bail out.
 552   //
 553   // NOTE: It would not have been correct to have used
 554   // CollectedHeap::fill_with_object() and make the space look like
 555   // an int array. The thread that is doing the allocation will
 556   // later update the object header to a potentially different array
 557   // type and, for a very short period of time, the klass and length
 558   // fields will be inconsistent. This could cause a refinement
 559   // thread to calculate the object size incorrectly.
 560   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 561 
 562   // We will set up the first region as "starts humongous". This
 563   // will also update the BOT covering all the regions to reflect
 564   // that there is a single object that starts at the bottom of the
 565   // first region.
 566   first_hr->set_starts_humongous(new_top, new_end);
 567   first_hr->set_allocation_context(context);
 568   // Then, if there are any, we will set up the "continues
 569   // humongous" regions.
 570   HeapRegion* hr = NULL;
 571   for (uint i = first + 1; i < last; ++i) {
 572     hr = region_at(i);
 573     hr->set_continues_humongous(first_hr);
 574     hr->set_allocation_context(context);
 575   }
 576   // If we have "continues humongous" regions (hr != NULL), then the
 577   // end of the last one should match new_end.
 578   assert(hr == NULL || hr->end() == new_end, "sanity");
 579 
 580   // Up to this point no concurrent thread would have been able to
 581   // do any scanning on any region in this series. All the top
 582   // fields still point to bottom, so the intersection between
 583   // [bottom,top] and [card_start,card_end] will be empty. Before we
 584   // update the top fields, we'll do a storestore to make sure that
 585   // no thread sees the update to top before the zeroing of the
 586   // object header and the BOT initialization.
 587   OrderAccess::storestore();
 588 
 589   // Now that the BOT and the object header have been initialized,
 590   // we can update top of the "starts humongous" region.
 591   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 592          "new_top should be in this region");
 593   first_hr->set_top(new_top);
 594   if (_hr_printer.is_active()) {
 595     HeapWord* bottom = first_hr->bottom();
 596     HeapWord* end = first_hr->orig_end();
 597     if ((first + 1) == last) {
 598       // the series has a single humongous region
 599       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 600     } else {
 601       // the series has more than one humongous regions
 602       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 603     }
 604   }
 605 
 606   // Now, we will update the top fields of the "continues humongous"
 607   // regions. The reason we need to do this is that, otherwise,
 608   // these regions would look empty and this will confuse parts of
 609   // G1. For example, the code that looks for a consecutive number
 610   // of empty regions will consider them empty and try to
 611   // re-allocate them. We can extend is_empty() to also include
 612   // !is_continues_humongous(), but it is easier to just update the top
 613   // fields here. The way we set top for all regions (i.e., top ==
 614   // end for all regions but the last one, top == new_top for the
 615   // last one) is actually used when we will free up the humongous
 616   // region in free_humongous_region().
 617   hr = NULL;
 618   for (uint i = first + 1; i < last; ++i) {
 619     hr = region_at(i);
 620     if ((i + 1) == last) {
 621       // last continues humongous region
 622       assert(hr->bottom() < new_top && new_top <= hr->end(),
 623              "new_top should fall on this region");
 624       hr->set_top(new_top);
 625       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 626     } else {
 627       // not last one
 628       assert(new_top > hr->end(), "new_top should be above this region");
 629       hr->set_top(hr->end());
 630       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 631     }
 632   }
 633   // If we have continues humongous regions (hr != NULL), then the
 634   // end of the last one should match new_end and its top should
 635   // match new_top.
 636   assert(hr == NULL ||
 637          (hr->end() == new_end && hr->top() == new_top), "sanity");
 638   check_bitmaps("Humongous Region Allocation", first_hr);
 639 
 640   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 641   _allocator->increase_used(first_hr->used());
 642   _humongous_set.add(first_hr);
 643 
 644   return new_obj;
 645 }
 646 
 647 // If could fit into free regions w/o expansion, try.
 648 // Otherwise, if can expand, do so.
 649 // Otherwise, if using ex regions might help, try with ex given back.
 650 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 651   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 652 
 653   verify_region_sets_optional();
 654 
 655   uint first = G1_NO_HRM_INDEX;
 656   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 657 
 658   if (obj_regions == 1) {
 659     // Only one region to allocate, try to use a fast path by directly allocating
 660     // from the free lists. Do not try to expand here, we will potentially do that
 661     // later.
 662     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 663     if (hr != NULL) {
 664       first = hr->hrm_index();
 665     }
 666   } else {
 667     // We can't allocate humongous regions spanning more than one region while
 668     // cleanupComplete() is running, since some of the regions we find to be
 669     // empty might not yet be added to the free list. It is not straightforward
 670     // to know in which list they are on so that we can remove them. We only
 671     // need to do this if we need to allocate more than one region to satisfy the
 672     // current humongous allocation request. If we are only allocating one region
 673     // we use the one-region region allocation code (see above), that already
 674     // potentially waits for regions from the secondary free list.
 675     wait_while_free_regions_coming();
 676     append_secondary_free_list_if_not_empty_with_lock();
 677 
 678     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 679     // are lucky enough to find some.
 680     first = _hrm.find_contiguous_only_empty(obj_regions);
 681     if (first != G1_NO_HRM_INDEX) {
 682       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 683     }
 684   }
 685 
 686   if (first == G1_NO_HRM_INDEX) {
 687     // Policy: We could not find enough regions for the humongous object in the
 688     // free list. Look through the heap to find a mix of free and uncommitted regions.
 689     // If so, try expansion.
 690     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 691     if (first != G1_NO_HRM_INDEX) {
 692       // We found something. Make sure these regions are committed, i.e. expand
 693       // the heap. Alternatively we could do a defragmentation GC.
 694       ergo_verbose1(ErgoHeapSizing,
 695                     "attempt heap expansion",
 696                     ergo_format_reason("humongous allocation request failed")
 697                     ergo_format_byte("allocation request"),
 698                     word_size * HeapWordSize);
 699 
 700       _hrm.expand_at(first, obj_regions);
 701       g1_policy()->record_new_heap_size(num_regions());
 702 
 703 #ifdef ASSERT
 704       for (uint i = first; i < first + obj_regions; ++i) {
 705         HeapRegion* hr = region_at(i);
 706         assert(hr->is_free(), "sanity");
 707         assert(hr->is_empty(), "sanity");
 708         assert(is_on_master_free_list(hr), "sanity");
 709       }
 710 #endif
 711       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 712     } else {
 713       // Policy: Potentially trigger a defragmentation GC.
 714     }
 715   }
 716 
 717   HeapWord* result = NULL;
 718   if (first != G1_NO_HRM_INDEX) {
 719     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 720                                                        word_size, context);
 721     assert(result != NULL, "it should always return a valid result");
 722 
 723     // A successful humongous object allocation changes the used space
 724     // information of the old generation so we need to recalculate the
 725     // sizes and update the jstat counters here.
 726     g1mm()->update_sizes();
 727   }
 728 
 729   verify_region_sets_optional();
 730 
 731   return result;
 732 }
 733 
 734 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 735   assert_heap_not_locked_and_not_at_safepoint();
 736   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 737 
 738   uint dummy_gc_count_before;
 739   uint dummy_gclocker_retry_count = 0;
 740   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 741 }
 742 
 743 HeapWord*
 744 G1CollectedHeap::mem_allocate(size_t word_size,
 745                               bool*  gc_overhead_limit_was_exceeded) {
 746   assert_heap_not_locked_and_not_at_safepoint();
 747 
 748   // Loop until the allocation is satisfied, or unsatisfied after GC.
 749   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 750     uint gc_count_before;
 751 
 752     HeapWord* result = NULL;
 753     if (!is_humongous(word_size)) {
 754       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 755     } else {
 756       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 757     }
 758     if (result != NULL) {
 759       return result;
 760     }
 761 
 762     // Create the garbage collection operation...
 763     VM_G1CollectForAllocation op(gc_count_before, word_size);
 764     op.set_allocation_context(AllocationContext::current());
 765 
 766     // ...and get the VM thread to execute it.
 767     VMThread::execute(&op);
 768 
 769     if (op.prologue_succeeded() && op.pause_succeeded()) {
 770       // If the operation was successful we'll return the result even
 771       // if it is NULL. If the allocation attempt failed immediately
 772       // after a Full GC, it's unlikely we'll be able to allocate now.
 773       HeapWord* result = op.result();
 774       if (result != NULL && !is_humongous(word_size)) {
 775         // Allocations that take place on VM operations do not do any
 776         // card dirtying and we have to do it here. We only have to do
 777         // this for non-humongous allocations, though.
 778         dirty_young_block(result, word_size);
 779       }
 780       return result;
 781     } else {
 782       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 783         return NULL;
 784       }
 785       assert(op.result() == NULL,
 786              "the result should be NULL if the VM op did not succeed");
 787     }
 788 
 789     // Give a warning if we seem to be looping forever.
 790     if ((QueuedAllocationWarningCount > 0) &&
 791         (try_count % QueuedAllocationWarningCount == 0)) {
 792       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 793     }
 794   }
 795 
 796   ShouldNotReachHere();
 797   return NULL;
 798 }
 799 
 800 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 801                                                    AllocationContext_t context,
 802                                                    uint* gc_count_before_ret,
 803                                                    uint* gclocker_retry_count_ret) {
 804   // Make sure you read the note in attempt_allocation_humongous().
 805 
 806   assert_heap_not_locked_and_not_at_safepoint();
 807   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 808          "be called for humongous allocation requests");
 809 
 810   // We should only get here after the first-level allocation attempt
 811   // (attempt_allocation()) failed to allocate.
 812 
 813   // We will loop until a) we manage to successfully perform the
 814   // allocation or b) we successfully schedule a collection which
 815   // fails to perform the allocation. b) is the only case when we'll
 816   // return NULL.
 817   HeapWord* result = NULL;
 818   for (int try_count = 1; /* we'll return */; try_count += 1) {
 819     bool should_try_gc;
 820     uint gc_count_before;
 821 
 822     {
 823       MutexLockerEx x(Heap_lock);
 824       result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
 825                                                                                     false /* bot_updates */);
 826       if (result != NULL) {
 827         return result;
 828       }
 829 
 830       // If we reach here, attempt_allocation_locked() above failed to
 831       // allocate a new region. So the mutator alloc region should be NULL.
 832       assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
 833 
 834       if (GC_locker::is_active_and_needs_gc()) {
 835         if (g1_policy()->can_expand_young_list()) {
 836           // No need for an ergo verbose message here,
 837           // can_expand_young_list() does this when it returns true.
 838           result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
 839                                                                                        false /* bot_updates */);
 840           if (result != NULL) {
 841             return result;
 842           }
 843         }
 844         should_try_gc = false;
 845       } else {
 846         // The GCLocker may not be active but the GCLocker initiated
 847         // GC may not yet have been performed (GCLocker::needs_gc()
 848         // returns true). In this case we do not try this GC and
 849         // wait until the GCLocker initiated GC is performed, and
 850         // then retry the allocation.
 851         if (GC_locker::needs_gc()) {
 852           should_try_gc = false;
 853         } else {
 854           // Read the GC count while still holding the Heap_lock.
 855           gc_count_before = total_collections();
 856           should_try_gc = true;
 857         }
 858       }
 859     }
 860 
 861     if (should_try_gc) {
 862       bool succeeded;
 863       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 864                                    GCCause::_g1_inc_collection_pause);
 865       if (result != NULL) {
 866         assert(succeeded, "only way to get back a non-NULL result");
 867         return result;
 868       }
 869 
 870       if (succeeded) {
 871         // If we get here we successfully scheduled a collection which
 872         // failed to allocate. No point in trying to allocate
 873         // further. We'll just return NULL.
 874         MutexLockerEx x(Heap_lock);
 875         *gc_count_before_ret = total_collections();
 876         return NULL;
 877       }
 878     } else {
 879       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 880         MutexLockerEx x(Heap_lock);
 881         *gc_count_before_ret = total_collections();
 882         return NULL;
 883       }
 884       // The GCLocker is either active or the GCLocker initiated
 885       // GC has not yet been performed. Stall until it is and
 886       // then retry the allocation.
 887       GC_locker::stall_until_clear();
 888       (*gclocker_retry_count_ret) += 1;
 889     }
 890 
 891     // We can reach here if we were unsuccessful in scheduling a
 892     // collection (because another thread beat us to it) or if we were
 893     // stalled due to the GC locker. In either can we should retry the
 894     // allocation attempt in case another thread successfully
 895     // performed a collection and reclaimed enough space. We do the
 896     // first attempt (without holding the Heap_lock) here and the
 897     // follow-on attempt will be at the start of the next loop
 898     // iteration (after taking the Heap_lock).
 899     result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
 900                                                                            false /* bot_updates */);
 901     if (result != NULL) {
 902       return result;
 903     }
 904 
 905     // Give a warning if we seem to be looping forever.
 906     if ((QueuedAllocationWarningCount > 0) &&
 907         (try_count % QueuedAllocationWarningCount == 0)) {
 908       warning("G1CollectedHeap::attempt_allocation_slow() "
 909               "retries %d times", try_count);
 910     }
 911   }
 912 
 913   ShouldNotReachHere();
 914   return NULL;
 915 }
 916 
 917 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 918                                                         uint* gc_count_before_ret,
 919                                                         uint* gclocker_retry_count_ret) {
 920   // The structure of this method has a lot of similarities to
 921   // attempt_allocation_slow(). The reason these two were not merged
 922   // into a single one is that such a method would require several "if
 923   // allocation is not humongous do this, otherwise do that"
 924   // conditional paths which would obscure its flow. In fact, an early
 925   // version of this code did use a unified method which was harder to
 926   // follow and, as a result, it had subtle bugs that were hard to
 927   // track down. So keeping these two methods separate allows each to
 928   // be more readable. It will be good to keep these two in sync as
 929   // much as possible.
 930 
 931   assert_heap_not_locked_and_not_at_safepoint();
 932   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 933          "should only be called for humongous allocations");
 934 
 935   // Humongous objects can exhaust the heap quickly, so we should check if we
 936   // need to start a marking cycle at each humongous object allocation. We do
 937   // the check before we do the actual allocation. The reason for doing it
 938   // before the allocation is that we avoid having to keep track of the newly
 939   // allocated memory while we do a GC.
 940   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 941                                            word_size)) {
 942     collect(GCCause::_g1_humongous_allocation);
 943   }
 944 
 945   // We will loop until a) we manage to successfully perform the
 946   // allocation or b) we successfully schedule a collection which
 947   // fails to perform the allocation. b) is the only case when we'll
 948   // return NULL.
 949   HeapWord* result = NULL;
 950   for (int try_count = 1; /* we'll return */; try_count += 1) {
 951     bool should_try_gc;
 952     uint gc_count_before;
 953 
 954     {
 955       MutexLockerEx x(Heap_lock);
 956 
 957       // Given that humongous objects are not allocated in young
 958       // regions, we'll first try to do the allocation without doing a
 959       // collection hoping that there's enough space in the heap.
 960       result = humongous_obj_allocate(word_size, AllocationContext::current());
 961       if (result != NULL) {
 962         return result;
 963       }
 964 
 965       if (GC_locker::is_active_and_needs_gc()) {
 966         should_try_gc = false;
 967       } else {
 968          // The GCLocker may not be active but the GCLocker initiated
 969         // GC may not yet have been performed (GCLocker::needs_gc()
 970         // returns true). In this case we do not try this GC and
 971         // wait until the GCLocker initiated GC is performed, and
 972         // then retry the allocation.
 973         if (GC_locker::needs_gc()) {
 974           should_try_gc = false;
 975         } else {
 976           // Read the GC count while still holding the Heap_lock.
 977           gc_count_before = total_collections();
 978           should_try_gc = true;
 979         }
 980       }
 981     }
 982 
 983     if (should_try_gc) {
 984       // If we failed to allocate the humongous object, we should try to
 985       // do a collection pause (if we're allowed) in case it reclaims
 986       // enough space for the allocation to succeed after the pause.
 987 
 988       bool succeeded;
 989       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 990                                    GCCause::_g1_humongous_allocation);
 991       if (result != NULL) {
 992         assert(succeeded, "only way to get back a non-NULL result");
 993         return result;
 994       }
 995 
 996       if (succeeded) {
 997         // If we get here we successfully scheduled a collection which
 998         // failed to allocate. No point in trying to allocate
 999         // further. We'll just return NULL.
1000         MutexLockerEx x(Heap_lock);
1001         *gc_count_before_ret = total_collections();
1002         return NULL;
1003       }
1004     } else {
1005       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1006         MutexLockerEx x(Heap_lock);
1007         *gc_count_before_ret = total_collections();
1008         return NULL;
1009       }
1010       // The GCLocker is either active or the GCLocker initiated
1011       // GC has not yet been performed. Stall until it is and
1012       // then retry the allocation.
1013       GC_locker::stall_until_clear();
1014       (*gclocker_retry_count_ret) += 1;
1015     }
1016 
1017     // We can reach here if we were unsuccessful in scheduling a
1018     // collection (because another thread beat us to it) or if we were
1019     // stalled due to the GC locker. In either can we should retry the
1020     // allocation attempt in case another thread successfully
1021     // performed a collection and reclaimed enough space.  Give a
1022     // warning if we seem to be looping forever.
1023 
1024     if ((QueuedAllocationWarningCount > 0) &&
1025         (try_count % QueuedAllocationWarningCount == 0)) {
1026       warning("G1CollectedHeap::attempt_allocation_humongous() "
1027               "retries %d times", try_count);
1028     }
1029   }
1030 
1031   ShouldNotReachHere();
1032   return NULL;
1033 }
1034 
1035 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1036                                                            AllocationContext_t context,
1037                                                            bool expect_null_mutator_alloc_region) {
1038   assert_at_safepoint(true /* should_be_vm_thread */);
1039   assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1040                                              !expect_null_mutator_alloc_region,
1041          "the current alloc region was unexpectedly found to be non-NULL");
1042 
1043   if (!is_humongous(word_size)) {
1044     return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1045                                                       false /* bot_updates */);
1046   } else {
1047     HeapWord* result = humongous_obj_allocate(word_size, context);
1048     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1049       g1_policy()->set_initiate_conc_mark_if_possible();
1050     }
1051     return result;
1052   }
1053 
1054   ShouldNotReachHere();
1055 }
1056 
1057 class PostMCRemSetClearClosure: public HeapRegionClosure {
1058   G1CollectedHeap* _g1h;
1059   ModRefBarrierSet* _mr_bs;
1060 public:
1061   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1062     _g1h(g1h), _mr_bs(mr_bs) {}
1063 
1064   bool doHeapRegion(HeapRegion* r) {
1065     HeapRegionRemSet* hrrs = r->rem_set();
1066 
1067     if (r->is_continues_humongous()) {
1068       // We'll assert that the strong code root list and RSet is empty
1069       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1070       assert(hrrs->occupied() == 0, "RSet should be empty");
1071       return false;
1072     }
1073 
1074     _g1h->reset_gc_time_stamps(r);
1075     hrrs->clear();
1076     // You might think here that we could clear just the cards
1077     // corresponding to the used region.  But no: if we leave a dirty card
1078     // in a region we might allocate into, then it would prevent that card
1079     // from being enqueued, and cause it to be missed.
1080     // Re: the performance cost: we shouldn't be doing full GC anyway!
1081     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1082 
1083     return false;
1084   }
1085 };
1086 
1087 void G1CollectedHeap::clear_rsets_post_compaction() {
1088   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1089   heap_region_iterate(&rs_clear);
1090 }
1091 
1092 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1093   G1CollectedHeap*   _g1h;
1094   UpdateRSOopClosure _cl;
1095   int                _worker_i;
1096 public:
1097   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1098     _cl(g1->g1_rem_set(), worker_i),
1099     _worker_i(worker_i),
1100     _g1h(g1)
1101   { }
1102 
1103   bool doHeapRegion(HeapRegion* r) {
1104     if (!r->is_continues_humongous()) {
1105       _cl.set_from(r);
1106       r->oop_iterate(&_cl);
1107     }
1108     return false;
1109   }
1110 };
1111 
1112 class ParRebuildRSTask: public AbstractGangTask {
1113   G1CollectedHeap* _g1;
1114   HeapRegionClaimer _hrclaimer;
1115 
1116 public:
1117   ParRebuildRSTask(G1CollectedHeap* g1) :
1118       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1119 
1120   void work(uint worker_id) {
1121     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1122     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1123   }
1124 };
1125 
1126 class PostCompactionPrinterClosure: public HeapRegionClosure {
1127 private:
1128   G1HRPrinter* _hr_printer;
1129 public:
1130   bool doHeapRegion(HeapRegion* hr) {
1131     assert(!hr->is_young(), "not expecting to find young regions");
1132     if (hr->is_free()) {
1133       // We only generate output for non-empty regions.
1134     } else if (hr->is_starts_humongous()) {
1135       if (hr->region_num() == 1) {
1136         // single humongous region
1137         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1138       } else {
1139         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1140       }
1141     } else if (hr->is_continues_humongous()) {
1142       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1143     } else if (hr->is_old()) {
1144       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1145     } else {
1146       ShouldNotReachHere();
1147     }
1148     return false;
1149   }
1150 
1151   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1152     : _hr_printer(hr_printer) { }
1153 };
1154 
1155 void G1CollectedHeap::print_hrm_post_compaction() {
1156   PostCompactionPrinterClosure cl(hr_printer());
1157   heap_region_iterate(&cl);
1158 }
1159 
1160 bool G1CollectedHeap::do_collection(bool explicit_gc,
1161                                     bool clear_all_soft_refs,
1162                                     size_t word_size) {
1163   assert_at_safepoint(true /* should_be_vm_thread */);
1164 
1165   if (GC_locker::check_active_before_gc()) {
1166     return false;
1167   }
1168 
1169   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1170   gc_timer->register_gc_start();
1171 
1172   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1173   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1174 
1175   SvcGCMarker sgcm(SvcGCMarker::FULL);
1176   ResourceMark rm;
1177 
1178   print_heap_before_gc();
1179   trace_heap_before_gc(gc_tracer);
1180 
1181   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1182 
1183   verify_region_sets_optional();
1184 
1185   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1186                            collector_policy()->should_clear_all_soft_refs();
1187 
1188   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1189 
1190   {
1191     IsGCActiveMark x;
1192 
1193     // Timing
1194     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1195     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1196 
1197     {
1198       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1199       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1200       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1201 
1202       g1_policy()->record_full_collection_start();
1203 
1204       // Note: When we have a more flexible GC logging framework that
1205       // allows us to add optional attributes to a GC log record we
1206       // could consider timing and reporting how long we wait in the
1207       // following two methods.
1208       wait_while_free_regions_coming();
1209       // If we start the compaction before the CM threads finish
1210       // scanning the root regions we might trip them over as we'll
1211       // be moving objects / updating references. So let's wait until
1212       // they are done. By telling them to abort, they should complete
1213       // early.
1214       _cm->root_regions()->abort();
1215       _cm->root_regions()->wait_until_scan_finished();
1216       append_secondary_free_list_if_not_empty_with_lock();
1217 
1218       gc_prologue(true);
1219       increment_total_collections(true /* full gc */);
1220       increment_old_marking_cycles_started();
1221 
1222       assert(used() == recalculate_used(), "Should be equal");
1223 
1224       verify_before_gc();
1225 
1226       check_bitmaps("Full GC Start");
1227       pre_full_gc_dump(gc_timer);
1228 
1229       COMPILER2_PRESENT(DerivedPointerTable::clear());
1230 
1231       // Disable discovery and empty the discovered lists
1232       // for the CM ref processor.
1233       ref_processor_cm()->disable_discovery();
1234       ref_processor_cm()->abandon_partial_discovery();
1235       ref_processor_cm()->verify_no_references_recorded();
1236 
1237       // Abandon current iterations of concurrent marking and concurrent
1238       // refinement, if any are in progress. We have to do this before
1239       // wait_until_scan_finished() below.
1240       concurrent_mark()->abort();
1241 
1242       // Make sure we'll choose a new allocation region afterwards.
1243       _allocator->release_mutator_alloc_region();
1244       _allocator->abandon_gc_alloc_regions();
1245       g1_rem_set()->cleanupHRRS();
1246 
1247       // We should call this after we retire any currently active alloc
1248       // regions so that all the ALLOC / RETIRE events are generated
1249       // before the start GC event.
1250       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1251 
1252       // We may have added regions to the current incremental collection
1253       // set between the last GC or pause and now. We need to clear the
1254       // incremental collection set and then start rebuilding it afresh
1255       // after this full GC.
1256       abandon_collection_set(g1_policy()->inc_cset_head());
1257       g1_policy()->clear_incremental_cset();
1258       g1_policy()->stop_incremental_cset_building();
1259 
1260       tear_down_region_sets(false /* free_list_only */);
1261       g1_policy()->set_gcs_are_young(true);
1262 
1263       // See the comments in g1CollectedHeap.hpp and
1264       // G1CollectedHeap::ref_processing_init() about
1265       // how reference processing currently works in G1.
1266 
1267       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1268       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1269 
1270       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1271       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1272 
1273       ref_processor_stw()->enable_discovery();
1274       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1275 
1276       // Do collection work
1277       {
1278         HandleMark hm;  // Discard invalid handles created during gc
1279         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1280       }
1281 
1282       assert(num_free_regions() == 0, "we should not have added any free regions");
1283       rebuild_region_sets(false /* free_list_only */);
1284 
1285       // Enqueue any discovered reference objects that have
1286       // not been removed from the discovered lists.
1287       ref_processor_stw()->enqueue_discovered_references();
1288 
1289       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1290 
1291       MemoryService::track_memory_usage();
1292 
1293       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1294       ref_processor_stw()->verify_no_references_recorded();
1295 
1296       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1297       ClassLoaderDataGraph::purge();
1298       MetaspaceAux::verify_metrics();
1299 
1300       // Note: since we've just done a full GC, concurrent
1301       // marking is no longer active. Therefore we need not
1302       // re-enable reference discovery for the CM ref processor.
1303       // That will be done at the start of the next marking cycle.
1304       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1305       ref_processor_cm()->verify_no_references_recorded();
1306 
1307       reset_gc_time_stamp();
1308       // Since everything potentially moved, we will clear all remembered
1309       // sets, and clear all cards.  Later we will rebuild remembered
1310       // sets. We will also reset the GC time stamps of the regions.
1311       clear_rsets_post_compaction();
1312       check_gc_time_stamps();
1313 
1314       // Resize the heap if necessary.
1315       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1316 
1317       if (_hr_printer.is_active()) {
1318         // We should do this after we potentially resize the heap so
1319         // that all the COMMIT / UNCOMMIT events are generated before
1320         // the end GC event.
1321 
1322         print_hrm_post_compaction();
1323         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1324       }
1325 
1326       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1327       if (hot_card_cache->use_cache()) {
1328         hot_card_cache->reset_card_counts();
1329         hot_card_cache->reset_hot_cache();
1330       }
1331 
1332       // Rebuild remembered sets of all regions.
1333       uint n_workers =
1334         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1335                                                 workers()->active_workers(),
1336                                                 Threads::number_of_non_daemon_threads());
1337       assert(UseDynamicNumberOfGCThreads ||
1338              n_workers == workers()->total_workers(),
1339              "If not dynamic should be using all the  workers");
1340       workers()->set_active_workers(n_workers);
1341       // Set parallel threads in the heap (_n_par_threads) only
1342       // before a parallel phase and always reset it to 0 after
1343       // the phase so that the number of parallel threads does
1344       // no get carried forward to a serial phase where there
1345       // may be code that is "possibly_parallel".
1346       set_par_threads(n_workers);
1347 
1348       ParRebuildRSTask rebuild_rs_task(this);
1349       assert(UseDynamicNumberOfGCThreads ||
1350              workers()->active_workers() == workers()->total_workers(),
1351              "Unless dynamic should use total workers");
1352       // Use the most recent number of  active workers
1353       assert(workers()->active_workers() > 0,
1354              "Active workers not properly set");
1355       set_par_threads(workers()->active_workers());
1356       workers()->run_task(&rebuild_rs_task);
1357       set_par_threads(0);
1358 
1359       // Rebuild the strong code root lists for each region
1360       rebuild_strong_code_roots();
1361 
1362       if (true) { // FIXME
1363         MetaspaceGC::compute_new_size();
1364       }
1365 
1366 #ifdef TRACESPINNING
1367       ParallelTaskTerminator::print_termination_counts();
1368 #endif
1369 
1370       // Discard all rset updates
1371       JavaThread::dirty_card_queue_set().abandon_logs();
1372       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1373 
1374       _young_list->reset_sampled_info();
1375       // At this point there should be no regions in the
1376       // entire heap tagged as young.
1377       assert(check_young_list_empty(true /* check_heap */),
1378              "young list should be empty at this point");
1379 
1380       // Update the number of full collections that have been completed.
1381       increment_old_marking_cycles_completed(false /* concurrent */);
1382 
1383       _hrm.verify_optional();
1384       verify_region_sets_optional();
1385 
1386       verify_after_gc();
1387 
1388       // Clear the previous marking bitmap, if needed for bitmap verification.
1389       // Note we cannot do this when we clear the next marking bitmap in
1390       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1391       // objects marked during a full GC against the previous bitmap.
1392       // But we need to clear it before calling check_bitmaps below since
1393       // the full GC has compacted objects and updated TAMS but not updated
1394       // the prev bitmap.
1395       if (G1VerifyBitmaps) {
1396         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1397       }
1398       check_bitmaps("Full GC End");
1399 
1400       // Start a new incremental collection set for the next pause
1401       assert(g1_policy()->collection_set() == NULL, "must be");
1402       g1_policy()->start_incremental_cset_building();
1403 
1404       clear_cset_fast_test();
1405 
1406       _allocator->init_mutator_alloc_region();
1407 
1408       g1_policy()->record_full_collection_end();
1409 
1410       if (G1Log::fine()) {
1411         g1_policy()->print_heap_transition();
1412       }
1413 
1414       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1415       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1416       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1417       // before any GC notifications are raised.
1418       g1mm()->update_sizes();
1419 
1420       gc_epilogue(true);
1421     }
1422 
1423     if (G1Log::finer()) {
1424       g1_policy()->print_detailed_heap_transition(true /* full */);
1425     }
1426 
1427     print_heap_after_gc();
1428     trace_heap_after_gc(gc_tracer);
1429 
1430     post_full_gc_dump(gc_timer);
1431 
1432     gc_timer->register_gc_end();
1433     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1434   }
1435 
1436   return true;
1437 }
1438 
1439 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1440   // do_collection() will return whether it succeeded in performing
1441   // the GC. Currently, there is no facility on the
1442   // do_full_collection() API to notify the caller than the collection
1443   // did not succeed (e.g., because it was locked out by the GC
1444   // locker). So, right now, we'll ignore the return value.
1445   bool dummy = do_collection(true,                /* explicit_gc */
1446                              clear_all_soft_refs,
1447                              0                    /* word_size */);
1448 }
1449 
1450 // This code is mostly copied from TenuredGeneration.
1451 void
1452 G1CollectedHeap::
1453 resize_if_necessary_after_full_collection(size_t word_size) {
1454   // Include the current allocation, if any, and bytes that will be
1455   // pre-allocated to support collections, as "used".
1456   const size_t used_after_gc = used();
1457   const size_t capacity_after_gc = capacity();
1458   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1459 
1460   // This is enforced in arguments.cpp.
1461   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1462          "otherwise the code below doesn't make sense");
1463 
1464   // We don't have floating point command-line arguments
1465   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1466   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1467   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1468   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1469 
1470   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1471   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1472 
1473   // We have to be careful here as these two calculations can overflow
1474   // 32-bit size_t's.
1475   double used_after_gc_d = (double) used_after_gc;
1476   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1477   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1478 
1479   // Let's make sure that they are both under the max heap size, which
1480   // by default will make them fit into a size_t.
1481   double desired_capacity_upper_bound = (double) max_heap_size;
1482   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1483                                     desired_capacity_upper_bound);
1484   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1485                                     desired_capacity_upper_bound);
1486 
1487   // We can now safely turn them into size_t's.
1488   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1489   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1490 
1491   // This assert only makes sense here, before we adjust them
1492   // with respect to the min and max heap size.
1493   assert(minimum_desired_capacity <= maximum_desired_capacity,
1494          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1495                  "maximum_desired_capacity = "SIZE_FORMAT,
1496                  minimum_desired_capacity, maximum_desired_capacity));
1497 
1498   // Should not be greater than the heap max size. No need to adjust
1499   // it with respect to the heap min size as it's a lower bound (i.e.,
1500   // we'll try to make the capacity larger than it, not smaller).
1501   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1502   // Should not be less than the heap min size. No need to adjust it
1503   // with respect to the heap max size as it's an upper bound (i.e.,
1504   // we'll try to make the capacity smaller than it, not greater).
1505   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1506 
1507   if (capacity_after_gc < minimum_desired_capacity) {
1508     // Don't expand unless it's significant
1509     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1510     ergo_verbose4(ErgoHeapSizing,
1511                   "attempt heap expansion",
1512                   ergo_format_reason("capacity lower than "
1513                                      "min desired capacity after Full GC")
1514                   ergo_format_byte("capacity")
1515                   ergo_format_byte("occupancy")
1516                   ergo_format_byte_perc("min desired capacity"),
1517                   capacity_after_gc, used_after_gc,
1518                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1519     expand(expand_bytes);
1520 
1521     // No expansion, now see if we want to shrink
1522   } else if (capacity_after_gc > maximum_desired_capacity) {
1523     // Capacity too large, compute shrinking size
1524     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1525     ergo_verbose4(ErgoHeapSizing,
1526                   "attempt heap shrinking",
1527                   ergo_format_reason("capacity higher than "
1528                                      "max desired capacity after Full GC")
1529                   ergo_format_byte("capacity")
1530                   ergo_format_byte("occupancy")
1531                   ergo_format_byte_perc("max desired capacity"),
1532                   capacity_after_gc, used_after_gc,
1533                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1534     shrink(shrink_bytes);
1535   }
1536 }
1537 
1538 
1539 HeapWord*
1540 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1541                                            AllocationContext_t context,
1542                                            bool* succeeded) {
1543   assert_at_safepoint(true /* should_be_vm_thread */);
1544 
1545   *succeeded = true;
1546   // Let's attempt the allocation first.
1547   HeapWord* result =
1548     attempt_allocation_at_safepoint(word_size,
1549                                     context,
1550                                     false /* expect_null_mutator_alloc_region */);
1551   if (result != NULL) {
1552     assert(*succeeded, "sanity");
1553     return result;
1554   }
1555 
1556   // In a G1 heap, we're supposed to keep allocation from failing by
1557   // incremental pauses.  Therefore, at least for now, we'll favor
1558   // expansion over collection.  (This might change in the future if we can
1559   // do something smarter than full collection to satisfy a failed alloc.)
1560   result = expand_and_allocate(word_size, context);
1561   if (result != NULL) {
1562     assert(*succeeded, "sanity");
1563     return result;
1564   }
1565 
1566   // Expansion didn't work, we'll try to do a Full GC.
1567   bool gc_succeeded = do_collection(false, /* explicit_gc */
1568                                     false, /* clear_all_soft_refs */
1569                                     word_size);
1570   if (!gc_succeeded) {
1571     *succeeded = false;
1572     return NULL;
1573   }
1574 
1575   // Retry the allocation
1576   result = attempt_allocation_at_safepoint(word_size,
1577                                            context,
1578                                            true /* expect_null_mutator_alloc_region */);
1579   if (result != NULL) {
1580     assert(*succeeded, "sanity");
1581     return result;
1582   }
1583 
1584   // Then, try a Full GC that will collect all soft references.
1585   gc_succeeded = do_collection(false, /* explicit_gc */
1586                                true,  /* clear_all_soft_refs */
1587                                word_size);
1588   if (!gc_succeeded) {
1589     *succeeded = false;
1590     return NULL;
1591   }
1592 
1593   // Retry the allocation once more
1594   result = attempt_allocation_at_safepoint(word_size,
1595                                            context,
1596                                            true /* expect_null_mutator_alloc_region */);
1597   if (result != NULL) {
1598     assert(*succeeded, "sanity");
1599     return result;
1600   }
1601 
1602   assert(!collector_policy()->should_clear_all_soft_refs(),
1603          "Flag should have been handled and cleared prior to this point");
1604 
1605   // What else?  We might try synchronous finalization later.  If the total
1606   // space available is large enough for the allocation, then a more
1607   // complete compaction phase than we've tried so far might be
1608   // appropriate.
1609   assert(*succeeded, "sanity");
1610   return NULL;
1611 }
1612 
1613 // Attempting to expand the heap sufficiently
1614 // to support an allocation of the given "word_size".  If
1615 // successful, perform the allocation and return the address of the
1616 // allocated block, or else "NULL".
1617 
1618 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1619   assert_at_safepoint(true /* should_be_vm_thread */);
1620 
1621   verify_region_sets_optional();
1622 
1623   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1624   ergo_verbose1(ErgoHeapSizing,
1625                 "attempt heap expansion",
1626                 ergo_format_reason("allocation request failed")
1627                 ergo_format_byte("allocation request"),
1628                 word_size * HeapWordSize);
1629   if (expand(expand_bytes)) {
1630     _hrm.verify_optional();
1631     verify_region_sets_optional();
1632     return attempt_allocation_at_safepoint(word_size,
1633                                            context,
1634                                            false /* expect_null_mutator_alloc_region */);
1635   }
1636   return NULL;
1637 }
1638 
1639 bool G1CollectedHeap::expand(size_t expand_bytes) {
1640   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1641   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1642                                        HeapRegion::GrainBytes);
1643   ergo_verbose2(ErgoHeapSizing,
1644                 "expand the heap",
1645                 ergo_format_byte("requested expansion amount")
1646                 ergo_format_byte("attempted expansion amount"),
1647                 expand_bytes, aligned_expand_bytes);
1648 
1649   if (is_maximal_no_gc()) {
1650     ergo_verbose0(ErgoHeapSizing,
1651                       "did not expand the heap",
1652                       ergo_format_reason("heap already fully expanded"));
1653     return false;
1654   }
1655 
1656   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1657   assert(regions_to_expand > 0, "Must expand by at least one region");
1658 
1659   uint expanded_by = _hrm.expand_by(regions_to_expand);
1660 
1661   if (expanded_by > 0) {
1662     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1663     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1664     g1_policy()->record_new_heap_size(num_regions());
1665   } else {
1666     ergo_verbose0(ErgoHeapSizing,
1667                   "did not expand the heap",
1668                   ergo_format_reason("heap expansion operation failed"));
1669     // The expansion of the virtual storage space was unsuccessful.
1670     // Let's see if it was because we ran out of swap.
1671     if (G1ExitOnExpansionFailure &&
1672         _hrm.available() >= regions_to_expand) {
1673       // We had head room...
1674       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1675     }
1676   }
1677   return regions_to_expand > 0;
1678 }
1679 
1680 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1681   size_t aligned_shrink_bytes =
1682     ReservedSpace::page_align_size_down(shrink_bytes);
1683   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1684                                          HeapRegion::GrainBytes);
1685   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1686 
1687   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1688   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1689 
1690   ergo_verbose3(ErgoHeapSizing,
1691                 "shrink the heap",
1692                 ergo_format_byte("requested shrinking amount")
1693                 ergo_format_byte("aligned shrinking amount")
1694                 ergo_format_byte("attempted shrinking amount"),
1695                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1696   if (num_regions_removed > 0) {
1697     g1_policy()->record_new_heap_size(num_regions());
1698   } else {
1699     ergo_verbose0(ErgoHeapSizing,
1700                   "did not shrink the heap",
1701                   ergo_format_reason("heap shrinking operation failed"));
1702   }
1703 }
1704 
1705 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1706   verify_region_sets_optional();
1707 
1708   // We should only reach here at the end of a Full GC which means we
1709   // should not not be holding to any GC alloc regions. The method
1710   // below will make sure of that and do any remaining clean up.
1711   _allocator->abandon_gc_alloc_regions();
1712 
1713   // Instead of tearing down / rebuilding the free lists here, we
1714   // could instead use the remove_all_pending() method on free_list to
1715   // remove only the ones that we need to remove.
1716   tear_down_region_sets(true /* free_list_only */);
1717   shrink_helper(shrink_bytes);
1718   rebuild_region_sets(true /* free_list_only */);
1719 
1720   _hrm.verify_optional();
1721   verify_region_sets_optional();
1722 }
1723 
1724 // Public methods.
1725 
1726 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1727 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1728 #endif // _MSC_VER
1729 
1730 
1731 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1732   CollectedHeap(),
1733   _g1_policy(policy_),
1734   _dirty_card_queue_set(false),
1735   _into_cset_dirty_card_queue_set(false),
1736   _is_alive_closure_cm(this),
1737   _is_alive_closure_stw(this),
1738   _ref_processor_cm(NULL),
1739   _ref_processor_stw(NULL),
1740   _bot_shared(NULL),
1741   _evac_failure_scan_stack(NULL),
1742   _mark_in_progress(false),
1743   _cg1r(NULL),
1744   _g1mm(NULL),
1745   _refine_cte_cl(NULL),
1746   _full_collection(false),
1747   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1748   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1749   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1750   _humongous_is_live(),
1751   _has_humongous_reclaim_candidates(false),
1752   _free_regions_coming(false),
1753   _young_list(new YoungList(this)),
1754   _gc_time_stamp(0),
1755   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1756   _old_plab_stats(OldPLABSize, PLABWeight),
1757   _expand_heap_after_alloc_failure(true),
1758   _surviving_young_words(NULL),
1759   _old_marking_cycles_started(0),
1760   _old_marking_cycles_completed(0),
1761   _concurrent_cycle_started(false),
1762   _heap_summary_sent(false),
1763   _in_cset_fast_test(),
1764   _dirty_cards_region_list(NULL),
1765   _worker_cset_start_region(NULL),
1766   _worker_cset_start_region_time_stamp(NULL),
1767   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1768   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1769   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1770   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1771 
1772   _g1h = this;
1773 
1774   _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1775                           /* are_GC_task_threads */true,
1776                           /* are_ConcurrentGC_threads */false);
1777   _workers->initialize_workers();
1778 
1779   _allocator = G1Allocator::create_allocator(_g1h);
1780   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1781 
1782   int n_queues = MAX2((int)ParallelGCThreads, 1);
1783   _task_queues = new RefToScanQueueSet(n_queues);
1784 
1785   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1786   assert(n_rem_sets > 0, "Invariant.");
1787 
1788   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1789   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1790   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1791 
1792   for (int i = 0; i < n_queues; i++) {
1793     RefToScanQueue* q = new RefToScanQueue();
1794     q->initialize();
1795     _task_queues->register_queue(i, q);
1796     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1797   }
1798   clear_cset_start_regions();
1799 
1800   // Initialize the G1EvacuationFailureALot counters and flags.
1801   NOT_PRODUCT(reset_evacuation_should_fail();)
1802 
1803   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1804 }
1805 
1806 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1807                                                                  size_t size,
1808                                                                  size_t translation_factor) {
1809   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1810   // Allocate a new reserved space, preferring to use large pages.
1811   ReservedSpace rs(size, preferred_page_size);
1812   G1RegionToSpaceMapper* result  =
1813     G1RegionToSpaceMapper::create_mapper(rs,
1814                                          size,
1815                                          rs.alignment(),
1816                                          HeapRegion::GrainBytes,
1817                                          translation_factor,
1818                                          mtGC);
1819   if (TracePageSizes) {
1820     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1821                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1822   }
1823   return result;
1824 }
1825 
1826 jint G1CollectedHeap::initialize() {
1827   CollectedHeap::pre_initialize();
1828   os::enable_vtime();
1829 
1830   G1Log::init();
1831 
1832   // Necessary to satisfy locking discipline assertions.
1833 
1834   MutexLocker x(Heap_lock);
1835 
1836   // We have to initialize the printer before committing the heap, as
1837   // it will be used then.
1838   _hr_printer.set_active(G1PrintHeapRegions);
1839 
1840   // While there are no constraints in the GC code that HeapWordSize
1841   // be any particular value, there are multiple other areas in the
1842   // system which believe this to be true (e.g. oop->object_size in some
1843   // cases incorrectly returns the size in wordSize units rather than
1844   // HeapWordSize).
1845   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1846 
1847   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1848   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1849   size_t heap_alignment = collector_policy()->heap_alignment();
1850 
1851   // Ensure that the sizes are properly aligned.
1852   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1853   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1854   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1855 
1856   _refine_cte_cl = new RefineCardTableEntryClosure();
1857 
1858   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1859 
1860   // Reserve the maximum.
1861 
1862   // When compressed oops are enabled, the preferred heap base
1863   // is calculated by subtracting the requested size from the
1864   // 32Gb boundary and using the result as the base address for
1865   // heap reservation. If the requested size is not aligned to
1866   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1867   // into the ReservedHeapSpace constructor) then the actual
1868   // base of the reserved heap may end up differing from the
1869   // address that was requested (i.e. the preferred heap base).
1870   // If this happens then we could end up using a non-optimal
1871   // compressed oops mode.
1872 
1873   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1874                                                  heap_alignment);
1875 
1876   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1877 
1878   // Create the barrier set for the entire reserved region.
1879   G1SATBCardTableLoggingModRefBS* bs
1880     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1881   bs->initialize();
1882   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1883   set_barrier_set(bs);
1884 
1885   // Also create a G1 rem set.
1886   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1887 
1888   // Carve out the G1 part of the heap.
1889 
1890   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1891   G1RegionToSpaceMapper* heap_storage =
1892     G1RegionToSpaceMapper::create_mapper(g1_rs,
1893                                          g1_rs.size(),
1894                                          UseLargePages ? os::large_page_size() : os::vm_page_size(),
1895                                          HeapRegion::GrainBytes,
1896                                          1,
1897                                          mtJavaHeap);
1898   heap_storage->set_mapping_changed_listener(&_listener);
1899 
1900   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1901   G1RegionToSpaceMapper* bot_storage =
1902     create_aux_memory_mapper("Block offset table",
1903                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1904                              G1BlockOffsetSharedArray::N_bytes);
1905 
1906   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1907   G1RegionToSpaceMapper* cardtable_storage =
1908     create_aux_memory_mapper("Card table",
1909                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1910                              G1BlockOffsetSharedArray::N_bytes);
1911 
1912   G1RegionToSpaceMapper* card_counts_storage =
1913     create_aux_memory_mapper("Card counts table",
1914                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1915                              G1BlockOffsetSharedArray::N_bytes);
1916 
1917   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1918   G1RegionToSpaceMapper* prev_bitmap_storage =
1919     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
1920   G1RegionToSpaceMapper* next_bitmap_storage =
1921     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
1922 
1923   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1924   g1_barrier_set()->initialize(cardtable_storage);
1925    // Do later initialization work for concurrent refinement.
1926   _cg1r->init(card_counts_storage);
1927 
1928   // 6843694 - ensure that the maximum region index can fit
1929   // in the remembered set structures.
1930   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1931   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1932 
1933   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1934   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1935   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1936             "too many cards per region");
1937 
1938   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1939 
1940   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1941 
1942   _g1h = this;
1943 
1944   _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1945   _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1946 
1947   // Create the ConcurrentMark data structure and thread.
1948   // (Must do this late, so that "max_regions" is defined.)
1949   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1950   if (_cm == NULL || !_cm->completed_initialization()) {
1951     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1952     return JNI_ENOMEM;
1953   }
1954   _cmThread = _cm->cmThread();
1955 
1956   // Initialize the from_card cache structure of HeapRegionRemSet.
1957   HeapRegionRemSet::init_heap(max_regions());
1958 
1959   // Now expand into the initial heap size.
1960   if (!expand(init_byte_size)) {
1961     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1962     return JNI_ENOMEM;
1963   }
1964 
1965   // Perform any initialization actions delegated to the policy.
1966   g1_policy()->init();
1967 
1968   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1969                                                SATB_Q_FL_lock,
1970                                                G1SATBProcessCompletedThreshold,
1971                                                Shared_SATB_Q_lock);
1972 
1973   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1974                                                 DirtyCardQ_CBL_mon,
1975                                                 DirtyCardQ_FL_lock,
1976                                                 concurrent_g1_refine()->yellow_zone(),
1977                                                 concurrent_g1_refine()->red_zone(),
1978                                                 Shared_DirtyCardQ_lock);
1979 
1980   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1981                                     DirtyCardQ_CBL_mon,
1982                                     DirtyCardQ_FL_lock,
1983                                     -1, // never trigger processing
1984                                     -1, // no limit on length
1985                                     Shared_DirtyCardQ_lock,
1986                                     &JavaThread::dirty_card_queue_set());
1987 
1988   // Initialize the card queue set used to hold cards containing
1989   // references into the collection set.
1990   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1991                                              DirtyCardQ_CBL_mon,
1992                                              DirtyCardQ_FL_lock,
1993                                              -1, // never trigger processing
1994                                              -1, // no limit on length
1995                                              Shared_DirtyCardQ_lock,
1996                                              &JavaThread::dirty_card_queue_set());
1997 
1998   // Here we allocate the dummy HeapRegion that is required by the
1999   // G1AllocRegion class.
2000   HeapRegion* dummy_region = _hrm.get_dummy_region();
2001 
2002   // We'll re-use the same region whether the alloc region will
2003   // require BOT updates or not and, if it doesn't, then a non-young
2004   // region will complain that it cannot support allocations without
2005   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2006   dummy_region->set_eden();
2007   // Make sure it's full.
2008   dummy_region->set_top(dummy_region->end());
2009   G1AllocRegion::setup(this, dummy_region);
2010 
2011   _allocator->init_mutator_alloc_region();
2012 
2013   // Do create of the monitoring and management support so that
2014   // values in the heap have been properly initialized.
2015   _g1mm = new G1MonitoringSupport(this);
2016 
2017   G1StringDedup::initialize();
2018 
2019   return JNI_OK;
2020 }
2021 
2022 void G1CollectedHeap::stop() {
2023   // Stop all concurrent threads. We do this to make sure these threads
2024   // do not continue to execute and access resources (e.g. gclog_or_tty)
2025   // that are destroyed during shutdown.
2026   _cg1r->stop();
2027   _cmThread->stop();
2028   if (G1StringDedup::is_enabled()) {
2029     G1StringDedup::stop();
2030   }
2031 }
2032 
2033 void G1CollectedHeap::clear_humongous_is_live_table() {
2034   guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2035   _humongous_is_live.clear();
2036 }
2037 
2038 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2039   return HeapRegion::max_region_size();
2040 }
2041 
2042 void G1CollectedHeap::post_initialize() {
2043   CollectedHeap::post_initialize();
2044   ref_processing_init();
2045 }
2046 
2047 void G1CollectedHeap::ref_processing_init() {
2048   // Reference processing in G1 currently works as follows:
2049   //
2050   // * There are two reference processor instances. One is
2051   //   used to record and process discovered references
2052   //   during concurrent marking; the other is used to
2053   //   record and process references during STW pauses
2054   //   (both full and incremental).
2055   // * Both ref processors need to 'span' the entire heap as
2056   //   the regions in the collection set may be dotted around.
2057   //
2058   // * For the concurrent marking ref processor:
2059   //   * Reference discovery is enabled at initial marking.
2060   //   * Reference discovery is disabled and the discovered
2061   //     references processed etc during remarking.
2062   //   * Reference discovery is MT (see below).
2063   //   * Reference discovery requires a barrier (see below).
2064   //   * Reference processing may or may not be MT
2065   //     (depending on the value of ParallelRefProcEnabled
2066   //     and ParallelGCThreads).
2067   //   * A full GC disables reference discovery by the CM
2068   //     ref processor and abandons any entries on it's
2069   //     discovered lists.
2070   //
2071   // * For the STW processor:
2072   //   * Non MT discovery is enabled at the start of a full GC.
2073   //   * Processing and enqueueing during a full GC is non-MT.
2074   //   * During a full GC, references are processed after marking.
2075   //
2076   //   * Discovery (may or may not be MT) is enabled at the start
2077   //     of an incremental evacuation pause.
2078   //   * References are processed near the end of a STW evacuation pause.
2079   //   * For both types of GC:
2080   //     * Discovery is atomic - i.e. not concurrent.
2081   //     * Reference discovery will not need a barrier.
2082 
2083   MemRegion mr = reserved_region();
2084 
2085   // Concurrent Mark ref processor
2086   _ref_processor_cm =
2087     new ReferenceProcessor(mr,    // span
2088                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2089                                 // mt processing
2090                            (int) ParallelGCThreads,
2091                                 // degree of mt processing
2092                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2093                                 // mt discovery
2094                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2095                                 // degree of mt discovery
2096                            false,
2097                                 // Reference discovery is not atomic
2098                            &_is_alive_closure_cm);
2099                                 // is alive closure
2100                                 // (for efficiency/performance)
2101 
2102   // STW ref processor
2103   _ref_processor_stw =
2104     new ReferenceProcessor(mr,    // span
2105                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2106                                 // mt processing
2107                            MAX2((int)ParallelGCThreads, 1),
2108                                 // degree of mt processing
2109                            (ParallelGCThreads > 1),
2110                                 // mt discovery
2111                            MAX2((int)ParallelGCThreads, 1),
2112                                 // degree of mt discovery
2113                            true,
2114                                 // Reference discovery is atomic
2115                            &_is_alive_closure_stw);
2116                                 // is alive closure
2117                                 // (for efficiency/performance)
2118 }
2119 
2120 size_t G1CollectedHeap::capacity() const {
2121   return _hrm.length() * HeapRegion::GrainBytes;
2122 }
2123 
2124 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2125   assert(!hr->is_continues_humongous(), "pre-condition");
2126   hr->reset_gc_time_stamp();
2127   if (hr->is_starts_humongous()) {
2128     uint first_index = hr->hrm_index() + 1;
2129     uint last_index = hr->last_hc_index();
2130     for (uint i = first_index; i < last_index; i += 1) {
2131       HeapRegion* chr = region_at(i);
2132       assert(chr->is_continues_humongous(), "sanity");
2133       chr->reset_gc_time_stamp();
2134     }
2135   }
2136 }
2137 
2138 #ifndef PRODUCT
2139 
2140 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2141 private:
2142   unsigned _gc_time_stamp;
2143   bool _failures;
2144 
2145 public:
2146   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2147     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2148 
2149   virtual bool doHeapRegion(HeapRegion* hr) {
2150     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2151     if (_gc_time_stamp != region_gc_time_stamp) {
2152       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2153                              "expected %d", HR_FORMAT_PARAMS(hr),
2154                              region_gc_time_stamp, _gc_time_stamp);
2155       _failures = true;
2156     }
2157     return false;
2158   }
2159 
2160   bool failures() { return _failures; }
2161 };
2162 
2163 void G1CollectedHeap::check_gc_time_stamps() {
2164   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2165   heap_region_iterate(&cl);
2166   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2167 }
2168 #endif // PRODUCT
2169 
2170 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2171                                                  DirtyCardQueue* into_cset_dcq,
2172                                                  bool concurrent,
2173                                                  uint worker_i) {
2174   // Clean cards in the hot card cache
2175   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2176   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2177 
2178   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2179   size_t n_completed_buffers = 0;
2180   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2181     n_completed_buffers++;
2182   }
2183   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2184   dcqs.clear_n_completed_buffers();
2185   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2186 }
2187 
2188 
2189 // Computes the sum of the storage used by the various regions.
2190 size_t G1CollectedHeap::used() const {
2191   return _allocator->used();
2192 }
2193 
2194 size_t G1CollectedHeap::used_unlocked() const {
2195   return _allocator->used_unlocked();
2196 }
2197 
2198 class SumUsedClosure: public HeapRegionClosure {
2199   size_t _used;
2200 public:
2201   SumUsedClosure() : _used(0) {}
2202   bool doHeapRegion(HeapRegion* r) {
2203     if (!r->is_continues_humongous()) {
2204       _used += r->used();
2205     }
2206     return false;
2207   }
2208   size_t result() { return _used; }
2209 };
2210 
2211 size_t G1CollectedHeap::recalculate_used() const {
2212   double recalculate_used_start = os::elapsedTime();
2213 
2214   SumUsedClosure blk;
2215   heap_region_iterate(&blk);
2216 
2217   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2218   return blk.result();
2219 }
2220 
2221 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2222   switch (cause) {
2223     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2224     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2225     case GCCause::_g1_humongous_allocation: return true;
2226     case GCCause::_update_allocation_context_stats_inc: return true;
2227     case GCCause::_wb_conc_mark:            return true;
2228     default:                                return false;
2229   }
2230 }
2231 
2232 #ifndef PRODUCT
2233 void G1CollectedHeap::allocate_dummy_regions() {
2234   // Let's fill up most of the region
2235   size_t word_size = HeapRegion::GrainWords - 1024;
2236   // And as a result the region we'll allocate will be humongous.
2237   guarantee(is_humongous(word_size), "sanity");
2238 
2239   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2240     // Let's use the existing mechanism for the allocation
2241     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2242                                                  AllocationContext::system());
2243     if (dummy_obj != NULL) {
2244       MemRegion mr(dummy_obj, word_size);
2245       CollectedHeap::fill_with_object(mr);
2246     } else {
2247       // If we can't allocate once, we probably cannot allocate
2248       // again. Let's get out of the loop.
2249       break;
2250     }
2251   }
2252 }
2253 #endif // !PRODUCT
2254 
2255 void G1CollectedHeap::increment_old_marking_cycles_started() {
2256   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2257     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2258     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2259     _old_marking_cycles_started, _old_marking_cycles_completed));
2260 
2261   _old_marking_cycles_started++;
2262 }
2263 
2264 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2265   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2266 
2267   // We assume that if concurrent == true, then the caller is a
2268   // concurrent thread that was joined the Suspendible Thread
2269   // Set. If there's ever a cheap way to check this, we should add an
2270   // assert here.
2271 
2272   // Given that this method is called at the end of a Full GC or of a
2273   // concurrent cycle, and those can be nested (i.e., a Full GC can
2274   // interrupt a concurrent cycle), the number of full collections
2275   // completed should be either one (in the case where there was no
2276   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2277   // behind the number of full collections started.
2278 
2279   // This is the case for the inner caller, i.e. a Full GC.
2280   assert(concurrent ||
2281          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2282          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2283          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2284                  "is inconsistent with _old_marking_cycles_completed = %u",
2285                  _old_marking_cycles_started, _old_marking_cycles_completed));
2286 
2287   // This is the case for the outer caller, i.e. the concurrent cycle.
2288   assert(!concurrent ||
2289          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2290          err_msg("for outer caller (concurrent cycle): "
2291                  "_old_marking_cycles_started = %u "
2292                  "is inconsistent with _old_marking_cycles_completed = %u",
2293                  _old_marking_cycles_started, _old_marking_cycles_completed));
2294 
2295   _old_marking_cycles_completed += 1;
2296 
2297   // We need to clear the "in_progress" flag in the CM thread before
2298   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2299   // is set) so that if a waiter requests another System.gc() it doesn't
2300   // incorrectly see that a marking cycle is still in progress.
2301   if (concurrent) {
2302     _cmThread->clear_in_progress();
2303   }
2304 
2305   // This notify_all() will ensure that a thread that called
2306   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2307   // and it's waiting for a full GC to finish will be woken up. It is
2308   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2309   FullGCCount_lock->notify_all();
2310 }
2311 
2312 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2313   _concurrent_cycle_started = true;
2314   _gc_timer_cm->register_gc_start(start_time);
2315 
2316   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2317   trace_heap_before_gc(_gc_tracer_cm);
2318 }
2319 
2320 void G1CollectedHeap::register_concurrent_cycle_end() {
2321   if (_concurrent_cycle_started) {
2322     if (_cm->has_aborted()) {
2323       _gc_tracer_cm->report_concurrent_mode_failure();
2324     }
2325 
2326     _gc_timer_cm->register_gc_end();
2327     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2328 
2329     // Clear state variables to prepare for the next concurrent cycle.
2330     _concurrent_cycle_started = false;
2331     _heap_summary_sent = false;
2332   }
2333 }
2334 
2335 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2336   if (_concurrent_cycle_started) {
2337     // This function can be called when:
2338     //  the cleanup pause is run
2339     //  the concurrent cycle is aborted before the cleanup pause.
2340     //  the concurrent cycle is aborted after the cleanup pause,
2341     //   but before the concurrent cycle end has been registered.
2342     // Make sure that we only send the heap information once.
2343     if (!_heap_summary_sent) {
2344       trace_heap_after_gc(_gc_tracer_cm);
2345       _heap_summary_sent = true;
2346     }
2347   }
2348 }
2349 
2350 G1YCType G1CollectedHeap::yc_type() {
2351   bool is_young = g1_policy()->gcs_are_young();
2352   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2353   bool is_during_mark = mark_in_progress();
2354 
2355   if (is_initial_mark) {
2356     return InitialMark;
2357   } else if (is_during_mark) {
2358     return DuringMark;
2359   } else if (is_young) {
2360     return Normal;
2361   } else {
2362     return Mixed;
2363   }
2364 }
2365 
2366 void G1CollectedHeap::collect(GCCause::Cause cause) {
2367   assert_heap_not_locked();
2368 
2369   uint gc_count_before;
2370   uint old_marking_count_before;
2371   uint full_gc_count_before;
2372   bool retry_gc;
2373 
2374   do {
2375     retry_gc = false;
2376 
2377     {
2378       MutexLocker ml(Heap_lock);
2379 
2380       // Read the GC count while holding the Heap_lock
2381       gc_count_before = total_collections();
2382       full_gc_count_before = total_full_collections();
2383       old_marking_count_before = _old_marking_cycles_started;
2384     }
2385 
2386     if (should_do_concurrent_full_gc(cause)) {
2387       // Schedule an initial-mark evacuation pause that will start a
2388       // concurrent cycle. We're setting word_size to 0 which means that
2389       // we are not requesting a post-GC allocation.
2390       VM_G1IncCollectionPause op(gc_count_before,
2391                                  0,     /* word_size */
2392                                  true,  /* should_initiate_conc_mark */
2393                                  g1_policy()->max_pause_time_ms(),
2394                                  cause);
2395       op.set_allocation_context(AllocationContext::current());
2396 
2397       VMThread::execute(&op);
2398       if (!op.pause_succeeded()) {
2399         if (old_marking_count_before == _old_marking_cycles_started) {
2400           retry_gc = op.should_retry_gc();
2401         } else {
2402           // A Full GC happened while we were trying to schedule the
2403           // initial-mark GC. No point in starting a new cycle given
2404           // that the whole heap was collected anyway.
2405         }
2406 
2407         if (retry_gc) {
2408           if (GC_locker::is_active_and_needs_gc()) {
2409             GC_locker::stall_until_clear();
2410           }
2411         }
2412       }
2413     } else {
2414       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2415           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2416 
2417         // Schedule a standard evacuation pause. We're setting word_size
2418         // to 0 which means that we are not requesting a post-GC allocation.
2419         VM_G1IncCollectionPause op(gc_count_before,
2420                                    0,     /* word_size */
2421                                    false, /* should_initiate_conc_mark */
2422                                    g1_policy()->max_pause_time_ms(),
2423                                    cause);
2424         VMThread::execute(&op);
2425       } else {
2426         // Schedule a Full GC.
2427         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2428         VMThread::execute(&op);
2429       }
2430     }
2431   } while (retry_gc);
2432 }
2433 
2434 bool G1CollectedHeap::is_in(const void* p) const {
2435   if (_hrm.reserved().contains(p)) {
2436     // Given that we know that p is in the reserved space,
2437     // heap_region_containing_raw() should successfully
2438     // return the containing region.
2439     HeapRegion* hr = heap_region_containing_raw(p);
2440     return hr->is_in(p);
2441   } else {
2442     return false;
2443   }
2444 }
2445 
2446 #ifdef ASSERT
2447 bool G1CollectedHeap::is_in_exact(const void* p) const {
2448   bool contains = reserved_region().contains(p);
2449   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2450   if (contains && available) {
2451     return true;
2452   } else {
2453     return false;
2454   }
2455 }
2456 #endif
2457 
2458 // Iteration functions.
2459 
2460 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2461 
2462 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2463   ExtendedOopClosure* _cl;
2464 public:
2465   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2466   bool doHeapRegion(HeapRegion* r) {
2467     if (!r->is_continues_humongous()) {
2468       r->oop_iterate(_cl);
2469     }
2470     return false;
2471   }
2472 };
2473 
2474 // Iterates an ObjectClosure over all objects within a HeapRegion.
2475 
2476 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2477   ObjectClosure* _cl;
2478 public:
2479   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2480   bool doHeapRegion(HeapRegion* r) {
2481     if (!r->is_continues_humongous()) {
2482       r->object_iterate(_cl);
2483     }
2484     return false;
2485   }
2486 };
2487 
2488 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2489   IterateObjectClosureRegionClosure blk(cl);
2490   heap_region_iterate(&blk);
2491 }
2492 
2493 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2494   _hrm.iterate(cl);
2495 }
2496 
2497 void
2498 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2499                                          uint worker_id,
2500                                          HeapRegionClaimer *hrclaimer,
2501                                          bool concurrent) const {
2502   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2503 }
2504 
2505 // Clear the cached CSet starting regions and (more importantly)
2506 // the time stamps. Called when we reset the GC time stamp.
2507 void G1CollectedHeap::clear_cset_start_regions() {
2508   assert(_worker_cset_start_region != NULL, "sanity");
2509   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2510 
2511   int n_queues = MAX2((int)ParallelGCThreads, 1);
2512   for (int i = 0; i < n_queues; i++) {
2513     _worker_cset_start_region[i] = NULL;
2514     _worker_cset_start_region_time_stamp[i] = 0;
2515   }
2516 }
2517 
2518 // Given the id of a worker, obtain or calculate a suitable
2519 // starting region for iterating over the current collection set.
2520 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2521   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2522 
2523   HeapRegion* result = NULL;
2524   unsigned gc_time_stamp = get_gc_time_stamp();
2525 
2526   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2527     // Cached starting region for current worker was set
2528     // during the current pause - so it's valid.
2529     // Note: the cached starting heap region may be NULL
2530     // (when the collection set is empty).
2531     result = _worker_cset_start_region[worker_i];
2532     assert(result == NULL || result->in_collection_set(), "sanity");
2533     return result;
2534   }
2535 
2536   // The cached entry was not valid so let's calculate
2537   // a suitable starting heap region for this worker.
2538 
2539   // We want the parallel threads to start their collection
2540   // set iteration at different collection set regions to
2541   // avoid contention.
2542   // If we have:
2543   //          n collection set regions
2544   //          p threads
2545   // Then thread t will start at region floor ((t * n) / p)
2546 
2547   result = g1_policy()->collection_set();
2548   uint cs_size = g1_policy()->cset_region_length();
2549   uint active_workers = workers()->active_workers();
2550   assert(UseDynamicNumberOfGCThreads ||
2551            active_workers == workers()->total_workers(),
2552            "Unless dynamic should use total workers");
2553 
2554   uint end_ind   = (cs_size * worker_i) / active_workers;
2555   uint start_ind = 0;
2556 
2557   if (worker_i > 0 &&
2558       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2559     // Previous workers starting region is valid
2560     // so let's iterate from there
2561     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2562     result = _worker_cset_start_region[worker_i - 1];
2563   }
2564 
2565   for (uint i = start_ind; i < end_ind; i++) {
2566     result = result->next_in_collection_set();
2567   }
2568 
2569   // Note: the calculated starting heap region may be NULL
2570   // (when the collection set is empty).
2571   assert(result == NULL || result->in_collection_set(), "sanity");
2572   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2573          "should be updated only once per pause");
2574   _worker_cset_start_region[worker_i] = result;
2575   OrderAccess::storestore();
2576   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2577   return result;
2578 }
2579 
2580 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2581   HeapRegion* r = g1_policy()->collection_set();
2582   while (r != NULL) {
2583     HeapRegion* next = r->next_in_collection_set();
2584     if (cl->doHeapRegion(r)) {
2585       cl->incomplete();
2586       return;
2587     }
2588     r = next;
2589   }
2590 }
2591 
2592 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2593                                                   HeapRegionClosure *cl) {
2594   if (r == NULL) {
2595     // The CSet is empty so there's nothing to do.
2596     return;
2597   }
2598 
2599   assert(r->in_collection_set(),
2600          "Start region must be a member of the collection set.");
2601   HeapRegion* cur = r;
2602   while (cur != NULL) {
2603     HeapRegion* next = cur->next_in_collection_set();
2604     if (cl->doHeapRegion(cur) && false) {
2605       cl->incomplete();
2606       return;
2607     }
2608     cur = next;
2609   }
2610   cur = g1_policy()->collection_set();
2611   while (cur != r) {
2612     HeapRegion* next = cur->next_in_collection_set();
2613     if (cl->doHeapRegion(cur) && false) {
2614       cl->incomplete();
2615       return;
2616     }
2617     cur = next;
2618   }
2619 }
2620 
2621 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2622   HeapRegion* result = _hrm.next_region_in_heap(from);
2623   while (result != NULL && result->is_humongous()) {
2624     result = _hrm.next_region_in_heap(result);
2625   }
2626   return result;
2627 }
2628 
2629 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2630   HeapRegion* hr = heap_region_containing(addr);
2631   return hr->block_start(addr);
2632 }
2633 
2634 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2635   HeapRegion* hr = heap_region_containing(addr);
2636   return hr->block_size(addr);
2637 }
2638 
2639 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2640   HeapRegion* hr = heap_region_containing(addr);
2641   return hr->block_is_obj(addr);
2642 }
2643 
2644 bool G1CollectedHeap::supports_tlab_allocation() const {
2645   return true;
2646 }
2647 
2648 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2649   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2650 }
2651 
2652 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2653   return young_list()->eden_used_bytes();
2654 }
2655 
2656 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2657 // must be smaller than the humongous object limit.
2658 size_t G1CollectedHeap::max_tlab_size() const {
2659   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2660 }
2661 
2662 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2663   // Return the remaining space in the cur alloc region, but not less than
2664   // the min TLAB size.
2665 
2666   // Also, this value can be at most the humongous object threshold,
2667   // since we can't allow tlabs to grow big enough to accommodate
2668   // humongous objects.
2669 
2670   HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2671   size_t max_tlab = max_tlab_size() * wordSize;
2672   if (hr == NULL) {
2673     return max_tlab;
2674   } else {
2675     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2676   }
2677 }
2678 
2679 size_t G1CollectedHeap::max_capacity() const {
2680   return _hrm.reserved().byte_size();
2681 }
2682 
2683 jlong G1CollectedHeap::millis_since_last_gc() {
2684   // assert(false, "NYI");
2685   return 0;
2686 }
2687 
2688 void G1CollectedHeap::prepare_for_verify() {
2689   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2690     ensure_parsability(false);
2691   }
2692   g1_rem_set()->prepare_for_verify();
2693 }
2694 
2695 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2696                                               VerifyOption vo) {
2697   switch (vo) {
2698   case VerifyOption_G1UsePrevMarking:
2699     return hr->obj_allocated_since_prev_marking(obj);
2700   case VerifyOption_G1UseNextMarking:
2701     return hr->obj_allocated_since_next_marking(obj);
2702   case VerifyOption_G1UseMarkWord:
2703     return false;
2704   default:
2705     ShouldNotReachHere();
2706   }
2707   return false; // keep some compilers happy
2708 }
2709 
2710 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2711   switch (vo) {
2712   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2713   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2714   case VerifyOption_G1UseMarkWord:    return NULL;
2715   default:                            ShouldNotReachHere();
2716   }
2717   return NULL; // keep some compilers happy
2718 }
2719 
2720 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2721   switch (vo) {
2722   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2723   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2724   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2725   default:                            ShouldNotReachHere();
2726   }
2727   return false; // keep some compilers happy
2728 }
2729 
2730 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2731   switch (vo) {
2732   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2733   case VerifyOption_G1UseNextMarking: return "NTAMS";
2734   case VerifyOption_G1UseMarkWord:    return "NONE";
2735   default:                            ShouldNotReachHere();
2736   }
2737   return NULL; // keep some compilers happy
2738 }
2739 
2740 class VerifyRootsClosure: public OopClosure {
2741 private:
2742   G1CollectedHeap* _g1h;
2743   VerifyOption     _vo;
2744   bool             _failures;
2745 public:
2746   // _vo == UsePrevMarking -> use "prev" marking information,
2747   // _vo == UseNextMarking -> use "next" marking information,
2748   // _vo == UseMarkWord    -> use mark word from object header.
2749   VerifyRootsClosure(VerifyOption vo) :
2750     _g1h(G1CollectedHeap::heap()),
2751     _vo(vo),
2752     _failures(false) { }
2753 
2754   bool failures() { return _failures; }
2755 
2756   template <class T> void do_oop_nv(T* p) {
2757     T heap_oop = oopDesc::load_heap_oop(p);
2758     if (!oopDesc::is_null(heap_oop)) {
2759       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2760       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2761         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2762                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
2763         if (_vo == VerifyOption_G1UseMarkWord) {
2764           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2765         }
2766         obj->print_on(gclog_or_tty);
2767         _failures = true;
2768       }
2769     }
2770   }
2771 
2772   void do_oop(oop* p)       { do_oop_nv(p); }
2773   void do_oop(narrowOop* p) { do_oop_nv(p); }
2774 };
2775 
2776 class G1VerifyCodeRootOopClosure: public OopClosure {
2777   G1CollectedHeap* _g1h;
2778   OopClosure* _root_cl;
2779   nmethod* _nm;
2780   VerifyOption _vo;
2781   bool _failures;
2782 
2783   template <class T> void do_oop_work(T* p) {
2784     // First verify that this root is live
2785     _root_cl->do_oop(p);
2786 
2787     if (!G1VerifyHeapRegionCodeRoots) {
2788       // We're not verifying the code roots attached to heap region.
2789       return;
2790     }
2791 
2792     // Don't check the code roots during marking verification in a full GC
2793     if (_vo == VerifyOption_G1UseMarkWord) {
2794       return;
2795     }
2796 
2797     // Now verify that the current nmethod (which contains p) is
2798     // in the code root list of the heap region containing the
2799     // object referenced by p.
2800 
2801     T heap_oop = oopDesc::load_heap_oop(p);
2802     if (!oopDesc::is_null(heap_oop)) {
2803       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2804 
2805       // Now fetch the region containing the object
2806       HeapRegion* hr = _g1h->heap_region_containing(obj);
2807       HeapRegionRemSet* hrrs = hr->rem_set();
2808       // Verify that the strong code root list for this region
2809       // contains the nmethod
2810       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2811         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2812                               "from nmethod "PTR_FORMAT" not in strong "
2813                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2814                               p, _nm, hr->bottom(), hr->end());
2815         _failures = true;
2816       }
2817     }
2818   }
2819 
2820 public:
2821   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2822     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2823 
2824   void do_oop(oop* p) { do_oop_work(p); }
2825   void do_oop(narrowOop* p) { do_oop_work(p); }
2826 
2827   void set_nmethod(nmethod* nm) { _nm = nm; }
2828   bool failures() { return _failures; }
2829 };
2830 
2831 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2832   G1VerifyCodeRootOopClosure* _oop_cl;
2833 
2834 public:
2835   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2836     _oop_cl(oop_cl) {}
2837 
2838   void do_code_blob(CodeBlob* cb) {
2839     nmethod* nm = cb->as_nmethod_or_null();
2840     if (nm != NULL) {
2841       _oop_cl->set_nmethod(nm);
2842       nm->oops_do(_oop_cl);
2843     }
2844   }
2845 };
2846 
2847 class YoungRefCounterClosure : public OopClosure {
2848   G1CollectedHeap* _g1h;
2849   int              _count;
2850  public:
2851   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2852   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2853   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2854 
2855   int count() { return _count; }
2856   void reset_count() { _count = 0; };
2857 };
2858 
2859 class VerifyKlassClosure: public KlassClosure {
2860   YoungRefCounterClosure _young_ref_counter_closure;
2861   OopClosure *_oop_closure;
2862  public:
2863   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2864   void do_klass(Klass* k) {
2865     k->oops_do(_oop_closure);
2866 
2867     _young_ref_counter_closure.reset_count();
2868     k->oops_do(&_young_ref_counter_closure);
2869     if (_young_ref_counter_closure.count() > 0) {
2870       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2871     }
2872   }
2873 };
2874 
2875 class VerifyLivenessOopClosure: public OopClosure {
2876   G1CollectedHeap* _g1h;
2877   VerifyOption _vo;
2878 public:
2879   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2880     _g1h(g1h), _vo(vo)
2881   { }
2882   void do_oop(narrowOop *p) { do_oop_work(p); }
2883   void do_oop(      oop *p) { do_oop_work(p); }
2884 
2885   template <class T> void do_oop_work(T *p) {
2886     oop obj = oopDesc::load_decode_heap_oop(p);
2887     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2888               "Dead object referenced by a not dead object");
2889   }
2890 };
2891 
2892 class VerifyObjsInRegionClosure: public ObjectClosure {
2893 private:
2894   G1CollectedHeap* _g1h;
2895   size_t _live_bytes;
2896   HeapRegion *_hr;
2897   VerifyOption _vo;
2898 public:
2899   // _vo == UsePrevMarking -> use "prev" marking information,
2900   // _vo == UseNextMarking -> use "next" marking information,
2901   // _vo == UseMarkWord    -> use mark word from object header.
2902   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2903     : _live_bytes(0), _hr(hr), _vo(vo) {
2904     _g1h = G1CollectedHeap::heap();
2905   }
2906   void do_object(oop o) {
2907     VerifyLivenessOopClosure isLive(_g1h, _vo);
2908     assert(o != NULL, "Huh?");
2909     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2910       // If the object is alive according to the mark word,
2911       // then verify that the marking information agrees.
2912       // Note we can't verify the contra-positive of the
2913       // above: if the object is dead (according to the mark
2914       // word), it may not be marked, or may have been marked
2915       // but has since became dead, or may have been allocated
2916       // since the last marking.
2917       if (_vo == VerifyOption_G1UseMarkWord) {
2918         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2919       }
2920 
2921       o->oop_iterate_no_header(&isLive);
2922       if (!_hr->obj_allocated_since_prev_marking(o)) {
2923         size_t obj_size = o->size();    // Make sure we don't overflow
2924         _live_bytes += (obj_size * HeapWordSize);
2925       }
2926     }
2927   }
2928   size_t live_bytes() { return _live_bytes; }
2929 };
2930 
2931 class PrintObjsInRegionClosure : public ObjectClosure {
2932   HeapRegion *_hr;
2933   G1CollectedHeap *_g1;
2934 public:
2935   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2936     _g1 = G1CollectedHeap::heap();
2937   };
2938 
2939   void do_object(oop o) {
2940     if (o != NULL) {
2941       HeapWord *start = (HeapWord *) o;
2942       size_t word_sz = o->size();
2943       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2944                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2945                           (void*) o, word_sz,
2946                           _g1->isMarkedPrev(o),
2947                           _g1->isMarkedNext(o),
2948                           _hr->obj_allocated_since_prev_marking(o));
2949       HeapWord *end = start + word_sz;
2950       HeapWord *cur;
2951       int *val;
2952       for (cur = start; cur < end; cur++) {
2953         val = (int *) cur;
2954         gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2955       }
2956     }
2957   }
2958 };
2959 
2960 class VerifyRegionClosure: public HeapRegionClosure {
2961 private:
2962   bool             _par;
2963   VerifyOption     _vo;
2964   bool             _failures;
2965 public:
2966   // _vo == UsePrevMarking -> use "prev" marking information,
2967   // _vo == UseNextMarking -> use "next" marking information,
2968   // _vo == UseMarkWord    -> use mark word from object header.
2969   VerifyRegionClosure(bool par, VerifyOption vo)
2970     : _par(par),
2971       _vo(vo),
2972       _failures(false) {}
2973 
2974   bool failures() {
2975     return _failures;
2976   }
2977 
2978   bool doHeapRegion(HeapRegion* r) {
2979     if (!r->is_continues_humongous()) {
2980       bool failures = false;
2981       r->verify(_vo, &failures);
2982       if (failures) {
2983         _failures = true;
2984       } else {
2985         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2986         r->object_iterate(&not_dead_yet_cl);
2987         if (_vo != VerifyOption_G1UseNextMarking) {
2988           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2989             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2990                                    "max_live_bytes "SIZE_FORMAT" "
2991                                    "< calculated "SIZE_FORMAT,
2992                                    r->bottom(), r->end(),
2993                                    r->max_live_bytes(),
2994                                  not_dead_yet_cl.live_bytes());
2995             _failures = true;
2996           }
2997         } else {
2998           // When vo == UseNextMarking we cannot currently do a sanity
2999           // check on the live bytes as the calculation has not been
3000           // finalized yet.
3001         }
3002       }
3003     }
3004     return false; // stop the region iteration if we hit a failure
3005   }
3006 };
3007 
3008 // This is the task used for parallel verification of the heap regions
3009 
3010 class G1ParVerifyTask: public AbstractGangTask {
3011 private:
3012   G1CollectedHeap*  _g1h;
3013   VerifyOption      _vo;
3014   bool              _failures;
3015   HeapRegionClaimer _hrclaimer;
3016 
3017 public:
3018   // _vo == UsePrevMarking -> use "prev" marking information,
3019   // _vo == UseNextMarking -> use "next" marking information,
3020   // _vo == UseMarkWord    -> use mark word from object header.
3021   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3022       AbstractGangTask("Parallel verify task"),
3023       _g1h(g1h),
3024       _vo(vo),
3025       _failures(false),
3026       _hrclaimer(g1h->workers()->active_workers()) {}
3027 
3028   bool failures() {
3029     return _failures;
3030   }
3031 
3032   void work(uint worker_id) {
3033     HandleMark hm;
3034     VerifyRegionClosure blk(true, _vo);
3035     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3036     if (blk.failures()) {
3037       _failures = true;
3038     }
3039   }
3040 };
3041 
3042 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3043   if (SafepointSynchronize::is_at_safepoint()) {
3044     assert(Thread::current()->is_VM_thread(),
3045            "Expected to be executed serially by the VM thread at this point");
3046 
3047     if (!silent) { gclog_or_tty->print("Roots "); }
3048     VerifyRootsClosure rootsCl(vo);
3049     VerifyKlassClosure klassCl(this, &rootsCl);
3050     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3051 
3052     // We apply the relevant closures to all the oops in the
3053     // system dictionary, class loader data graph, the string table
3054     // and the nmethods in the code cache.
3055     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3056     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3057 
3058     {
3059       G1RootProcessor root_processor(this);
3060       root_processor.process_all_roots(&rootsCl,
3061                                        &cldCl,
3062                                        &blobsCl);
3063     }
3064 
3065     bool failures = rootsCl.failures() || codeRootsCl.failures();
3066 
3067     if (vo != VerifyOption_G1UseMarkWord) {
3068       // If we're verifying during a full GC then the region sets
3069       // will have been torn down at the start of the GC. Therefore
3070       // verifying the region sets will fail. So we only verify
3071       // the region sets when not in a full GC.
3072       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3073       verify_region_sets();
3074     }
3075 
3076     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3077     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3078 
3079       G1ParVerifyTask task(this, vo);
3080       assert(UseDynamicNumberOfGCThreads ||
3081         workers()->active_workers() == workers()->total_workers(),
3082         "If not dynamic should be using all the workers");
3083       int n_workers = workers()->active_workers();
3084       set_par_threads(n_workers);
3085       workers()->run_task(&task);
3086       set_par_threads(0);
3087       if (task.failures()) {
3088         failures = true;
3089       }
3090 
3091     } else {
3092       VerifyRegionClosure blk(false, vo);
3093       heap_region_iterate(&blk);
3094       if (blk.failures()) {
3095         failures = true;
3096       }
3097     }
3098 
3099     if (G1StringDedup::is_enabled()) {
3100       if (!silent) gclog_or_tty->print("StrDedup ");
3101       G1StringDedup::verify();
3102     }
3103 
3104     if (failures) {
3105       gclog_or_tty->print_cr("Heap:");
3106       // It helps to have the per-region information in the output to
3107       // help us track down what went wrong. This is why we call
3108       // print_extended_on() instead of print_on().
3109       print_extended_on(gclog_or_tty);
3110       gclog_or_tty->cr();
3111 #ifndef PRODUCT
3112       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3113         concurrent_mark()->print_reachable("at-verification-failure",
3114                                            vo, false /* all */);
3115       }
3116 #endif
3117       gclog_or_tty->flush();
3118     }
3119     guarantee(!failures, "there should not have been any failures");
3120   } else {
3121     if (!silent) {
3122       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3123       if (G1StringDedup::is_enabled()) {
3124         gclog_or_tty->print(", StrDedup");
3125       }
3126       gclog_or_tty->print(") ");
3127     }
3128   }
3129 }
3130 
3131 void G1CollectedHeap::verify(bool silent) {
3132   verify(silent, VerifyOption_G1UsePrevMarking);
3133 }
3134 
3135 double G1CollectedHeap::verify(bool guard, const char* msg) {
3136   double verify_time_ms = 0.0;
3137 
3138   if (guard && total_collections() >= VerifyGCStartAt) {
3139     double verify_start = os::elapsedTime();
3140     HandleMark hm;  // Discard invalid handles created during verification
3141     prepare_for_verify();
3142     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3143     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3144   }
3145 
3146   return verify_time_ms;
3147 }
3148 
3149 void G1CollectedHeap::verify_before_gc() {
3150   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3151   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3152 }
3153 
3154 void G1CollectedHeap::verify_after_gc() {
3155   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3156   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3157 }
3158 
3159 class PrintRegionClosure: public HeapRegionClosure {
3160   outputStream* _st;
3161 public:
3162   PrintRegionClosure(outputStream* st) : _st(st) {}
3163   bool doHeapRegion(HeapRegion* r) {
3164     r->print_on(_st);
3165     return false;
3166   }
3167 };
3168 
3169 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3170                                        const HeapRegion* hr,
3171                                        const VerifyOption vo) const {
3172   switch (vo) {
3173   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3174   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3175   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3176   default:                            ShouldNotReachHere();
3177   }
3178   return false; // keep some compilers happy
3179 }
3180 
3181 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3182                                        const VerifyOption vo) const {
3183   switch (vo) {
3184   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3185   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3186   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3187   default:                            ShouldNotReachHere();
3188   }
3189   return false; // keep some compilers happy
3190 }
3191 
3192 void G1CollectedHeap::print_on(outputStream* st) const {
3193   st->print(" %-20s", "garbage-first heap");
3194   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3195             capacity()/K, used_unlocked()/K);
3196   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3197             _hrm.reserved().start(),
3198             _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3199             _hrm.reserved().end());
3200   st->cr();
3201   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3202   uint young_regions = _young_list->length();
3203   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3204             (size_t) young_regions * HeapRegion::GrainBytes / K);
3205   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3206   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3207             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3208   st->cr();
3209   MetaspaceAux::print_on(st);
3210 }
3211 
3212 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3213   print_on(st);
3214 
3215   // Print the per-region information.
3216   st->cr();
3217   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3218                "HS=humongous(starts), HC=humongous(continues), "
3219                "CS=collection set, F=free, TS=gc time stamp, "
3220                "PTAMS=previous top-at-mark-start, "
3221                "NTAMS=next top-at-mark-start)");
3222   PrintRegionClosure blk(st);
3223   heap_region_iterate(&blk);
3224 }
3225 
3226 void G1CollectedHeap::print_on_error(outputStream* st) const {
3227   this->CollectedHeap::print_on_error(st);
3228 
3229   if (_cm != NULL) {
3230     st->cr();
3231     _cm->print_on_error(st);
3232   }
3233 }
3234 
3235 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3236   workers()->print_worker_threads_on(st);
3237   _cmThread->print_on(st);
3238   st->cr();
3239   _cm->print_worker_threads_on(st);
3240   _cg1r->print_worker_threads_on(st);
3241   if (G1StringDedup::is_enabled()) {
3242     G1StringDedup::print_worker_threads_on(st);
3243   }
3244 }
3245 
3246 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3247   workers()->threads_do(tc);
3248   tc->do_thread(_cmThread);
3249   _cg1r->threads_do(tc);
3250   if (G1StringDedup::is_enabled()) {
3251     G1StringDedup::threads_do(tc);
3252   }
3253 }
3254 
3255 void G1CollectedHeap::print_tracing_info() const {
3256   // We'll overload this to mean "trace GC pause statistics."
3257   if (TraceYoungGenTime || TraceOldGenTime) {
3258     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3259     // to that.
3260     g1_policy()->print_tracing_info();
3261   }
3262   if (G1SummarizeRSetStats) {
3263     g1_rem_set()->print_summary_info();
3264   }
3265   if (G1SummarizeConcMark) {
3266     concurrent_mark()->print_summary_info();
3267   }
3268   g1_policy()->print_yg_surv_rate_info();
3269 }
3270 
3271 #ifndef PRODUCT
3272 // Helpful for debugging RSet issues.
3273 
3274 class PrintRSetsClosure : public HeapRegionClosure {
3275 private:
3276   const char* _msg;
3277   size_t _occupied_sum;
3278 
3279 public:
3280   bool doHeapRegion(HeapRegion* r) {
3281     HeapRegionRemSet* hrrs = r->rem_set();
3282     size_t occupied = hrrs->occupied();
3283     _occupied_sum += occupied;
3284 
3285     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3286                            HR_FORMAT_PARAMS(r));
3287     if (occupied == 0) {
3288       gclog_or_tty->print_cr("  RSet is empty");
3289     } else {
3290       hrrs->print();
3291     }
3292     gclog_or_tty->print_cr("----------");
3293     return false;
3294   }
3295 
3296   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3297     gclog_or_tty->cr();
3298     gclog_or_tty->print_cr("========================================");
3299     gclog_or_tty->print_cr("%s", msg);
3300     gclog_or_tty->cr();
3301   }
3302 
3303   ~PrintRSetsClosure() {
3304     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3305     gclog_or_tty->print_cr("========================================");
3306     gclog_or_tty->cr();
3307   }
3308 };
3309 
3310 void G1CollectedHeap::print_cset_rsets() {
3311   PrintRSetsClosure cl("Printing CSet RSets");
3312   collection_set_iterate(&cl);
3313 }
3314 
3315 void G1CollectedHeap::print_all_rsets() {
3316   PrintRSetsClosure cl("Printing All RSets");;
3317   heap_region_iterate(&cl);
3318 }
3319 #endif // PRODUCT
3320 
3321 G1CollectedHeap* G1CollectedHeap::heap() {
3322   assert(_g1h != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3323   assert(_g1h->kind() == CollectedHeap::G1CollectedHeap, "Not a G1 heap");
3324   return _g1h;
3325 }
3326 
3327 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3328   // always_do_update_barrier = false;
3329   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3330   // Fill TLAB's and such
3331   accumulate_statistics_all_tlabs();
3332   ensure_parsability(true);
3333 
3334   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3335       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3336     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3337   }
3338 }
3339 
3340 void G1CollectedHeap::gc_epilogue(bool full) {
3341 
3342   if (G1SummarizeRSetStats &&
3343       (G1SummarizeRSetStatsPeriod > 0) &&
3344       // we are at the end of the GC. Total collections has already been increased.
3345       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3346     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3347   }
3348 
3349   // FIXME: what is this about?
3350   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3351   // is set.
3352   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3353                         "derived pointer present"));
3354   // always_do_update_barrier = true;
3355 
3356   resize_all_tlabs();
3357   allocation_context_stats().update(full);
3358 
3359   // We have just completed a GC. Update the soft reference
3360   // policy with the new heap occupancy
3361   Universe::update_heap_info_at_gc();
3362 }
3363 
3364 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3365                                                uint gc_count_before,
3366                                                bool* succeeded,
3367                                                GCCause::Cause gc_cause) {
3368   assert_heap_not_locked_and_not_at_safepoint();
3369   g1_policy()->record_stop_world_start();
3370   VM_G1IncCollectionPause op(gc_count_before,
3371                              word_size,
3372                              false, /* should_initiate_conc_mark */
3373                              g1_policy()->max_pause_time_ms(),
3374                              gc_cause);
3375 
3376   op.set_allocation_context(AllocationContext::current());
3377   VMThread::execute(&op);
3378 
3379   HeapWord* result = op.result();
3380   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3381   assert(result == NULL || ret_succeeded,
3382          "the result should be NULL if the VM did not succeed");
3383   *succeeded = ret_succeeded;
3384 
3385   assert_heap_not_locked();
3386   return result;
3387 }
3388 
3389 void
3390 G1CollectedHeap::doConcurrentMark() {
3391   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3392   if (!_cmThread->in_progress()) {
3393     _cmThread->set_started();
3394     CGC_lock->notify();
3395   }
3396 }
3397 
3398 size_t G1CollectedHeap::pending_card_num() {
3399   size_t extra_cards = 0;
3400   JavaThread *curr = Threads::first();
3401   while (curr != NULL) {
3402     DirtyCardQueue& dcq = curr->dirty_card_queue();
3403     extra_cards += dcq.size();
3404     curr = curr->next();
3405   }
3406   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3407   size_t buffer_size = dcqs.buffer_size();
3408   size_t buffer_num = dcqs.completed_buffers_num();
3409 
3410   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3411   // in bytes - not the number of 'entries'. We need to convert
3412   // into a number of cards.
3413   return (buffer_size * buffer_num + extra_cards) / oopSize;
3414 }
3415 
3416 size_t G1CollectedHeap::cards_scanned() {
3417   return g1_rem_set()->cardsScanned();
3418 }
3419 
3420 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3421   HeapRegion* region = region_at(index);
3422   assert(region->is_starts_humongous(), "Must start a humongous object");
3423   return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3424 }
3425 
3426 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3427  private:
3428   size_t _total_humongous;
3429   size_t _candidate_humongous;
3430 
3431   DirtyCardQueue _dcq;
3432 
3433   bool humongous_region_is_candidate(uint index) {
3434     HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3435     assert(region->is_starts_humongous(), "Must start a humongous object");
3436     HeapRegionRemSet* const rset = region->rem_set();
3437     bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3438     return !oop(region->bottom())->is_objArray() &&
3439            ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3440             (!allow_stale_refs && rset->is_empty()));
3441   }
3442 
3443  public:
3444   RegisterHumongousWithInCSetFastTestClosure()
3445   : _total_humongous(0),
3446     _candidate_humongous(0),
3447     _dcq(&JavaThread::dirty_card_queue_set()) {
3448   }
3449 
3450   virtual bool doHeapRegion(HeapRegion* r) {
3451     if (!r->is_starts_humongous()) {
3452       return false;
3453     }
3454     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3455 
3456     uint region_idx = r->hrm_index();
3457     bool is_candidate = humongous_region_is_candidate(region_idx);
3458     // Is_candidate already filters out humongous object with large remembered sets.
3459     // If we have a humongous object with a few remembered sets, we simply flush these
3460     // remembered set entries into the DCQS. That will result in automatic
3461     // re-evaluation of their remembered set entries during the following evacuation
3462     // phase.
3463     if (is_candidate) {
3464       if (!r->rem_set()->is_empty()) {
3465         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3466                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3467         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3468         HeapRegionRemSetIterator hrrs(r->rem_set());
3469         size_t card_index;
3470         while (hrrs.has_next(card_index)) {
3471           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3472           // The remembered set might contain references to already freed
3473           // regions. Filter out such entries to avoid failing card table
3474           // verification.
3475           if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3476             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3477               *card_ptr = CardTableModRefBS::dirty_card_val();
3478               _dcq.enqueue(card_ptr);
3479             }
3480           }
3481         }
3482         r->rem_set()->clear_locked();
3483       }
3484       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3485       g1h->register_humongous_region_with_cset(region_idx);
3486       _candidate_humongous++;
3487     }
3488     _total_humongous++;
3489 
3490     return false;
3491   }
3492 
3493   size_t total_humongous() const { return _total_humongous; }
3494   size_t candidate_humongous() const { return _candidate_humongous; }
3495 
3496   void flush_rem_set_entries() { _dcq.flush(); }
3497 };
3498 
3499 void G1CollectedHeap::register_humongous_regions_with_cset() {
3500   if (!G1EagerReclaimHumongousObjects) {
3501     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3502     return;
3503   }
3504   double time = os::elapsed_counter();
3505 
3506   RegisterHumongousWithInCSetFastTestClosure cl;
3507   heap_region_iterate(&cl);
3508 
3509   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3510   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3511                                                                   cl.total_humongous(),
3512                                                                   cl.candidate_humongous());
3513   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3514 
3515   if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3516     clear_humongous_is_live_table();
3517   }
3518 
3519   // Finally flush all remembered set entries to re-check into the global DCQS.
3520   cl.flush_rem_set_entries();
3521 }
3522 
3523 void
3524 G1CollectedHeap::setup_surviving_young_words() {
3525   assert(_surviving_young_words == NULL, "pre-condition");
3526   uint array_length = g1_policy()->young_cset_region_length();
3527   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3528   if (_surviving_young_words == NULL) {
3529     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3530                           "Not enough space for young surv words summary.");
3531   }
3532   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3533 #ifdef ASSERT
3534   for (uint i = 0;  i < array_length; ++i) {
3535     assert( _surviving_young_words[i] == 0, "memset above" );
3536   }
3537 #endif // !ASSERT
3538 }
3539 
3540 void
3541 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3542   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3543   uint array_length = g1_policy()->young_cset_region_length();
3544   for (uint i = 0; i < array_length; ++i) {
3545     _surviving_young_words[i] += surv_young_words[i];
3546   }
3547 }
3548 
3549 void
3550 G1CollectedHeap::cleanup_surviving_young_words() {
3551   guarantee( _surviving_young_words != NULL, "pre-condition" );
3552   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3553   _surviving_young_words = NULL;
3554 }
3555 
3556 #ifdef ASSERT
3557 class VerifyCSetClosure: public HeapRegionClosure {
3558 public:
3559   bool doHeapRegion(HeapRegion* hr) {
3560     // Here we check that the CSet region's RSet is ready for parallel
3561     // iteration. The fields that we'll verify are only manipulated
3562     // when the region is part of a CSet and is collected. Afterwards,
3563     // we reset these fields when we clear the region's RSet (when the
3564     // region is freed) so they are ready when the region is
3565     // re-allocated. The only exception to this is if there's an
3566     // evacuation failure and instead of freeing the region we leave
3567     // it in the heap. In that case, we reset these fields during
3568     // evacuation failure handling.
3569     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3570 
3571     // Here's a good place to add any other checks we'd like to
3572     // perform on CSet regions.
3573     return false;
3574   }
3575 };
3576 #endif // ASSERT
3577 
3578 #if TASKQUEUE_STATS
3579 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3580   st->print_raw_cr("GC Task Stats");
3581   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3582   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3583 }
3584 
3585 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3586   print_taskqueue_stats_hdr(st);
3587 
3588   TaskQueueStats totals;
3589   const int n = workers()->total_workers();
3590   for (int i = 0; i < n; ++i) {
3591     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3592     totals += task_queue(i)->stats;
3593   }
3594   st->print_raw("tot "); totals.print(st); st->cr();
3595 
3596   DEBUG_ONLY(totals.verify());
3597 }
3598 
3599 void G1CollectedHeap::reset_taskqueue_stats() {
3600   const int n = workers()->total_workers();
3601   for (int i = 0; i < n; ++i) {
3602     task_queue(i)->stats.reset();
3603   }
3604 }
3605 #endif // TASKQUEUE_STATS
3606 
3607 void G1CollectedHeap::log_gc_header() {
3608   if (!G1Log::fine()) {
3609     return;
3610   }
3611 
3612   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3613 
3614   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3615     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3616     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3617 
3618   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3619 }
3620 
3621 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3622   if (!G1Log::fine()) {
3623     return;
3624   }
3625 
3626   if (G1Log::finer()) {
3627     if (evacuation_failed()) {
3628       gclog_or_tty->print(" (to-space exhausted)");
3629     }
3630     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3631     g1_policy()->phase_times()->note_gc_end();
3632     g1_policy()->phase_times()->print(pause_time_sec);
3633     g1_policy()->print_detailed_heap_transition();
3634   } else {
3635     if (evacuation_failed()) {
3636       gclog_or_tty->print("--");
3637     }
3638     g1_policy()->print_heap_transition();
3639     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3640   }
3641   gclog_or_tty->flush();
3642 }
3643 
3644 bool
3645 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3646   assert_at_safepoint(true /* should_be_vm_thread */);
3647   guarantee(!is_gc_active(), "collection is not reentrant");
3648 
3649   if (GC_locker::check_active_before_gc()) {
3650     return false;
3651   }
3652 
3653   _gc_timer_stw->register_gc_start();
3654 
3655   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3656 
3657   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3658   ResourceMark rm;
3659 
3660   print_heap_before_gc();
3661   trace_heap_before_gc(_gc_tracer_stw);
3662 
3663   verify_region_sets_optional();
3664   verify_dirty_young_regions();
3665 
3666   // This call will decide whether this pause is an initial-mark
3667   // pause. If it is, during_initial_mark_pause() will return true
3668   // for the duration of this pause.
3669   g1_policy()->decide_on_conc_mark_initiation();
3670 
3671   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3672   assert(!g1_policy()->during_initial_mark_pause() ||
3673           g1_policy()->gcs_are_young(), "sanity");
3674 
3675   // We also do not allow mixed GCs during marking.
3676   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3677 
3678   // Record whether this pause is an initial mark. When the current
3679   // thread has completed its logging output and it's safe to signal
3680   // the CM thread, the flag's value in the policy has been reset.
3681   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3682 
3683   // Inner scope for scope based logging, timers, and stats collection
3684   {
3685     EvacuationInfo evacuation_info;
3686 
3687     if (g1_policy()->during_initial_mark_pause()) {
3688       // We are about to start a marking cycle, so we increment the
3689       // full collection counter.
3690       increment_old_marking_cycles_started();
3691       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3692     }
3693 
3694     _gc_tracer_stw->report_yc_type(yc_type());
3695 
3696     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3697 
3698     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3699                                                                   workers()->active_workers(),
3700                                                                   Threads::number_of_non_daemon_threads());
3701     assert(UseDynamicNumberOfGCThreads ||
3702            active_workers == workers()->total_workers(),
3703            "If not dynamic should be using all the  workers");
3704     workers()->set_active_workers(active_workers);
3705 
3706     double pause_start_sec = os::elapsedTime();
3707     g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3708     log_gc_header();
3709 
3710     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3711     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3712 
3713     // If the secondary_free_list is not empty, append it to the
3714     // free_list. No need to wait for the cleanup operation to finish;
3715     // the region allocation code will check the secondary_free_list
3716     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3717     // set, skip this step so that the region allocation code has to
3718     // get entries from the secondary_free_list.
3719     if (!G1StressConcRegionFreeing) {
3720       append_secondary_free_list_if_not_empty_with_lock();
3721     }
3722 
3723     assert(check_young_list_well_formed(), "young list should be well formed");
3724 
3725     // Don't dynamically change the number of GC threads this early.  A value of
3726     // 0 is used to indicate serial work.  When parallel work is done,
3727     // it will be set.
3728 
3729     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3730       IsGCActiveMark x;
3731 
3732       gc_prologue(false);
3733       increment_total_collections(false /* full gc */);
3734       increment_gc_time_stamp();
3735 
3736       verify_before_gc();
3737 
3738       check_bitmaps("GC Start");
3739 
3740       COMPILER2_PRESENT(DerivedPointerTable::clear());
3741 
3742       // Please see comment in g1CollectedHeap.hpp and
3743       // G1CollectedHeap::ref_processing_init() to see how
3744       // reference processing currently works in G1.
3745 
3746       // Enable discovery in the STW reference processor
3747       ref_processor_stw()->enable_discovery();
3748 
3749       {
3750         // We want to temporarily turn off discovery by the
3751         // CM ref processor, if necessary, and turn it back on
3752         // on again later if we do. Using a scoped
3753         // NoRefDiscovery object will do this.
3754         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3755 
3756         // Forget the current alloc region (we might even choose it to be part
3757         // of the collection set!).
3758         _allocator->release_mutator_alloc_region();
3759 
3760         // We should call this after we retire the mutator alloc
3761         // region(s) so that all the ALLOC / RETIRE events are generated
3762         // before the start GC event.
3763         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3764 
3765         // This timing is only used by the ergonomics to handle our pause target.
3766         // It is unclear why this should not include the full pause. We will
3767         // investigate this in CR 7178365.
3768         //
3769         // Preserving the old comment here if that helps the investigation:
3770         //
3771         // The elapsed time induced by the start time below deliberately elides
3772         // the possible verification above.
3773         double sample_start_time_sec = os::elapsedTime();
3774 
3775 #if YOUNG_LIST_VERBOSE
3776         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3777         _young_list->print();
3778         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3779 #endif // YOUNG_LIST_VERBOSE
3780 
3781         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3782 
3783         double scan_wait_start = os::elapsedTime();
3784         // We have to wait until the CM threads finish scanning the
3785         // root regions as it's the only way to ensure that all the
3786         // objects on them have been correctly scanned before we start
3787         // moving them during the GC.
3788         bool waited = _cm->root_regions()->wait_until_scan_finished();
3789         double wait_time_ms = 0.0;
3790         if (waited) {
3791           double scan_wait_end = os::elapsedTime();
3792           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3793         }
3794         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3795 
3796 #if YOUNG_LIST_VERBOSE
3797         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3798         _young_list->print();
3799 #endif // YOUNG_LIST_VERBOSE
3800 
3801         if (g1_policy()->during_initial_mark_pause()) {
3802           concurrent_mark()->checkpointRootsInitialPre();
3803         }
3804 
3805 #if YOUNG_LIST_VERBOSE
3806         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3807         _young_list->print();
3808         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3809 #endif // YOUNG_LIST_VERBOSE
3810 
3811         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3812 
3813         register_humongous_regions_with_cset();
3814 
3815         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3816 
3817         _cm->note_start_of_gc();
3818         // We should not verify the per-thread SATB buffers given that
3819         // we have not filtered them yet (we'll do so during the
3820         // GC). We also call this after finalize_cset() to
3821         // ensure that the CSet has been finalized.
3822         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3823                                  true  /* verify_enqueued_buffers */,
3824                                  false /* verify_thread_buffers */,
3825                                  true  /* verify_fingers */);
3826 
3827         if (_hr_printer.is_active()) {
3828           HeapRegion* hr = g1_policy()->collection_set();
3829           while (hr != NULL) {
3830             _hr_printer.cset(hr);
3831             hr = hr->next_in_collection_set();
3832           }
3833         }
3834 
3835 #ifdef ASSERT
3836         VerifyCSetClosure cl;
3837         collection_set_iterate(&cl);
3838 #endif // ASSERT
3839 
3840         setup_surviving_young_words();
3841 
3842         // Initialize the GC alloc regions.
3843         _allocator->init_gc_alloc_regions(evacuation_info);
3844 
3845         // Actually do the work...
3846         evacuate_collection_set(evacuation_info);
3847 
3848         // We do this to mainly verify the per-thread SATB buffers
3849         // (which have been filtered by now) since we didn't verify
3850         // them earlier. No point in re-checking the stacks / enqueued
3851         // buffers given that the CSet has not changed since last time
3852         // we checked.
3853         _cm->verify_no_cset_oops(false /* verify_stacks */,
3854                                  false /* verify_enqueued_buffers */,
3855                                  true  /* verify_thread_buffers */,
3856                                  true  /* verify_fingers */);
3857 
3858         free_collection_set(g1_policy()->collection_set(), evacuation_info);
3859 
3860         eagerly_reclaim_humongous_regions();
3861 
3862         g1_policy()->clear_collection_set();
3863 
3864         cleanup_surviving_young_words();
3865 
3866         // Start a new incremental collection set for the next pause.
3867         g1_policy()->start_incremental_cset_building();
3868 
3869         clear_cset_fast_test();
3870 
3871         _young_list->reset_sampled_info();
3872 
3873         // Don't check the whole heap at this point as the
3874         // GC alloc regions from this pause have been tagged
3875         // as survivors and moved on to the survivor list.
3876         // Survivor regions will fail the !is_young() check.
3877         assert(check_young_list_empty(false /* check_heap */),
3878           "young list should be empty");
3879 
3880 #if YOUNG_LIST_VERBOSE
3881         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3882         _young_list->print();
3883 #endif // YOUNG_LIST_VERBOSE
3884 
3885         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3886                                              _young_list->first_survivor_region(),
3887                                              _young_list->last_survivor_region());
3888 
3889         _young_list->reset_auxilary_lists();
3890 
3891         if (evacuation_failed()) {
3892           _allocator->set_used(recalculate_used());
3893           uint n_queues = MAX2((int)ParallelGCThreads, 1);
3894           for (uint i = 0; i < n_queues; i++) {
3895             if (_evacuation_failed_info_array[i].has_failed()) {
3896               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3897             }
3898           }
3899         } else {
3900           // The "used" of the the collection set have already been subtracted
3901           // when they were freed.  Add in the bytes evacuated.
3902           _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3903         }
3904 
3905         if (g1_policy()->during_initial_mark_pause()) {
3906           // We have to do this before we notify the CM threads that
3907           // they can start working to make sure that all the
3908           // appropriate initialization is done on the CM object.
3909           concurrent_mark()->checkpointRootsInitialPost();
3910           set_marking_started();
3911           // Note that we don't actually trigger the CM thread at
3912           // this point. We do that later when we're sure that
3913           // the current thread has completed its logging output.
3914         }
3915 
3916         allocate_dummy_regions();
3917 
3918 #if YOUNG_LIST_VERBOSE
3919         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3920         _young_list->print();
3921         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3922 #endif // YOUNG_LIST_VERBOSE
3923 
3924         _allocator->init_mutator_alloc_region();
3925 
3926         {
3927           size_t expand_bytes = g1_policy()->expansion_amount();
3928           if (expand_bytes > 0) {
3929             size_t bytes_before = capacity();
3930             // No need for an ergo verbose message here,
3931             // expansion_amount() does this when it returns a value > 0.
3932             if (!expand(expand_bytes)) {
3933               // We failed to expand the heap. Cannot do anything about it.
3934             }
3935           }
3936         }
3937 
3938         // We redo the verification but now wrt to the new CSet which
3939         // has just got initialized after the previous CSet was freed.
3940         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3941                                  true  /* verify_enqueued_buffers */,
3942                                  true  /* verify_thread_buffers */,
3943                                  true  /* verify_fingers */);
3944         _cm->note_end_of_gc();
3945 
3946         // This timing is only used by the ergonomics to handle our pause target.
3947         // It is unclear why this should not include the full pause. We will
3948         // investigate this in CR 7178365.
3949         double sample_end_time_sec = os::elapsedTime();
3950         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3951         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3952 
3953         MemoryService::track_memory_usage();
3954 
3955         // In prepare_for_verify() below we'll need to scan the deferred
3956         // update buffers to bring the RSets up-to-date if
3957         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3958         // the update buffers we'll probably need to scan cards on the
3959         // regions we just allocated to (i.e., the GC alloc
3960         // regions). However, during the last GC we called
3961         // set_saved_mark() on all the GC alloc regions, so card
3962         // scanning might skip the [saved_mark_word()...top()] area of
3963         // those regions (i.e., the area we allocated objects into
3964         // during the last GC). But it shouldn't. Given that
3965         // saved_mark_word() is conditional on whether the GC time stamp
3966         // on the region is current or not, by incrementing the GC time
3967         // stamp here we invalidate all the GC time stamps on all the
3968         // regions and saved_mark_word() will simply return top() for
3969         // all the regions. This is a nicer way of ensuring this rather
3970         // than iterating over the regions and fixing them. In fact, the
3971         // GC time stamp increment here also ensures that
3972         // saved_mark_word() will return top() between pauses, i.e.,
3973         // during concurrent refinement. So we don't need the
3974         // is_gc_active() check to decided which top to use when
3975         // scanning cards (see CR 7039627).
3976         increment_gc_time_stamp();
3977 
3978         verify_after_gc();
3979         check_bitmaps("GC End");
3980 
3981         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3982         ref_processor_stw()->verify_no_references_recorded();
3983 
3984         // CM reference discovery will be re-enabled if necessary.
3985       }
3986 
3987       // We should do this after we potentially expand the heap so
3988       // that all the COMMIT events are generated before the end GC
3989       // event, and after we retire the GC alloc regions so that all
3990       // RETIRE events are generated before the end GC event.
3991       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3992 
3993 #ifdef TRACESPINNING
3994       ParallelTaskTerminator::print_termination_counts();
3995 #endif
3996 
3997       gc_epilogue(false);
3998     }
3999 
4000     // Print the remainder of the GC log output.
4001     log_gc_footer(os::elapsedTime() - pause_start_sec);
4002 
4003     // It is not yet to safe to tell the concurrent mark to
4004     // start as we have some optional output below. We don't want the
4005     // output from the concurrent mark thread interfering with this
4006     // logging output either.
4007 
4008     _hrm.verify_optional();
4009     verify_region_sets_optional();
4010 
4011     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4012     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4013 
4014     print_heap_after_gc();
4015     trace_heap_after_gc(_gc_tracer_stw);
4016 
4017     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4018     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4019     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4020     // before any GC notifications are raised.
4021     g1mm()->update_sizes();
4022 
4023     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4024     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4025     _gc_timer_stw->register_gc_end();
4026     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4027   }
4028   // It should now be safe to tell the concurrent mark thread to start
4029   // without its logging output interfering with the logging output
4030   // that came from the pause.
4031 
4032   if (should_start_conc_mark) {
4033     // CAUTION: after the doConcurrentMark() call below,
4034     // the concurrent marking thread(s) could be running
4035     // concurrently with us. Make sure that anything after
4036     // this point does not assume that we are the only GC thread
4037     // running. Note: of course, the actual marking work will
4038     // not start until the safepoint itself is released in
4039     // SuspendibleThreadSet::desynchronize().
4040     doConcurrentMark();
4041   }
4042 
4043   return true;
4044 }
4045 
4046 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4047   _drain_in_progress = false;
4048   set_evac_failure_closure(cl);
4049   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4050 }
4051 
4052 void G1CollectedHeap::finalize_for_evac_failure() {
4053   assert(_evac_failure_scan_stack != NULL &&
4054          _evac_failure_scan_stack->length() == 0,
4055          "Postcondition");
4056   assert(!_drain_in_progress, "Postcondition");
4057   delete _evac_failure_scan_stack;
4058   _evac_failure_scan_stack = NULL;
4059 }
4060 
4061 void G1CollectedHeap::remove_self_forwarding_pointers() {
4062   double remove_self_forwards_start = os::elapsedTime();
4063 
4064   set_par_threads();
4065   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4066   workers()->run_task(&rsfp_task);
4067   set_par_threads(0);
4068 
4069   // Now restore saved marks, if any.
4070   assert(_objs_with_preserved_marks.size() ==
4071             _preserved_marks_of_objs.size(), "Both or none.");
4072   while (!_objs_with_preserved_marks.is_empty()) {
4073     oop obj = _objs_with_preserved_marks.pop();
4074     markOop m = _preserved_marks_of_objs.pop();
4075     obj->set_mark(m);
4076   }
4077   _objs_with_preserved_marks.clear(true);
4078   _preserved_marks_of_objs.clear(true);
4079 
4080   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4081 }
4082 
4083 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4084   _evac_failure_scan_stack->push(obj);
4085 }
4086 
4087 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4088   assert(_evac_failure_scan_stack != NULL, "precondition");
4089 
4090   while (_evac_failure_scan_stack->length() > 0) {
4091      oop obj = _evac_failure_scan_stack->pop();
4092      _evac_failure_closure->set_region(heap_region_containing(obj));
4093      obj->oop_iterate_backwards(_evac_failure_closure);
4094   }
4095 }
4096 
4097 oop
4098 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4099                                                oop old) {
4100   assert(obj_in_cs(old),
4101          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4102                  (HeapWord*) old));
4103   markOop m = old->mark();
4104   oop forward_ptr = old->forward_to_atomic(old);
4105   if (forward_ptr == NULL) {
4106     // Forward-to-self succeeded.
4107     assert(_par_scan_state != NULL, "par scan state");
4108     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4109     uint queue_num = _par_scan_state->queue_num();
4110 
4111     _evacuation_failed = true;
4112     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4113     if (_evac_failure_closure != cl) {
4114       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4115       assert(!_drain_in_progress,
4116              "Should only be true while someone holds the lock.");
4117       // Set the global evac-failure closure to the current thread's.
4118       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4119       set_evac_failure_closure(cl);
4120       // Now do the common part.
4121       handle_evacuation_failure_common(old, m);
4122       // Reset to NULL.
4123       set_evac_failure_closure(NULL);
4124     } else {
4125       // The lock is already held, and this is recursive.
4126       assert(_drain_in_progress, "This should only be the recursive case.");
4127       handle_evacuation_failure_common(old, m);
4128     }
4129     return old;
4130   } else {
4131     // Forward-to-self failed. Either someone else managed to allocate
4132     // space for this object (old != forward_ptr) or they beat us in
4133     // self-forwarding it (old == forward_ptr).
4134     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4135            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4136                    "should not be in the CSet",
4137                    (HeapWord*) old, (HeapWord*) forward_ptr));
4138     return forward_ptr;
4139   }
4140 }
4141 
4142 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4143   preserve_mark_if_necessary(old, m);
4144 
4145   HeapRegion* r = heap_region_containing(old);
4146   if (!r->evacuation_failed()) {
4147     r->set_evacuation_failed(true);
4148     _hr_printer.evac_failure(r);
4149   }
4150 
4151   push_on_evac_failure_scan_stack(old);
4152 
4153   if (!_drain_in_progress) {
4154     // prevent recursion in copy_to_survivor_space()
4155     _drain_in_progress = true;
4156     drain_evac_failure_scan_stack();
4157     _drain_in_progress = false;
4158   }
4159 }
4160 
4161 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4162   assert(evacuation_failed(), "Oversaving!");
4163   // We want to call the "for_promotion_failure" version only in the
4164   // case of a promotion failure.
4165   if (m->must_be_preserved_for_promotion_failure(obj)) {
4166     _objs_with_preserved_marks.push(obj);
4167     _preserved_marks_of_objs.push(m);
4168   }
4169 }
4170 
4171 void G1ParCopyHelper::mark_object(oop obj) {
4172   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4173 
4174   // We know that the object is not moving so it's safe to read its size.
4175   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4176 }
4177 
4178 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4179   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4180   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4181   assert(from_obj != to_obj, "should not be self-forwarded");
4182 
4183   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4184   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4185 
4186   // The object might be in the process of being copied by another
4187   // worker so we cannot trust that its to-space image is
4188   // well-formed. So we have to read its size from its from-space
4189   // image which we know should not be changing.
4190   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4191 }
4192 
4193 template <class T>
4194 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4195   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4196     _scanned_klass->record_modified_oops();
4197   }
4198 }
4199 
4200 template <G1Barrier barrier, G1Mark do_mark_object>
4201 template <class T>
4202 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4203   T heap_oop = oopDesc::load_heap_oop(p);
4204 
4205   if (oopDesc::is_null(heap_oop)) {
4206     return;
4207   }
4208 
4209   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4210 
4211   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4212 
4213   const InCSetState state = _g1->in_cset_state(obj);
4214   if (state.is_in_cset()) {
4215     oop forwardee;
4216     markOop m = obj->mark();
4217     if (m->is_marked()) {
4218       forwardee = (oop) m->decode_pointer();
4219     } else {
4220       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4221     }
4222     assert(forwardee != NULL, "forwardee should not be NULL");
4223     oopDesc::encode_store_heap_oop(p, forwardee);
4224     if (do_mark_object != G1MarkNone && forwardee != obj) {
4225       // If the object is self-forwarded we don't need to explicitly
4226       // mark it, the evacuation failure protocol will do so.
4227       mark_forwarded_object(obj, forwardee);
4228     }
4229 
4230     if (barrier == G1BarrierKlass) {
4231       do_klass_barrier(p, forwardee);
4232     }
4233   } else {
4234     if (state.is_humongous()) {
4235       _g1->set_humongous_is_live(obj);
4236     }
4237     // The object is not in collection set. If we're a root scanning
4238     // closure during an initial mark pause then attempt to mark the object.
4239     if (do_mark_object == G1MarkFromRoot) {
4240       mark_object(obj);
4241     }
4242   }
4243 
4244   if (barrier == G1BarrierEvac) {
4245     _par_scan_state->update_rs(_from, p, _worker_id);
4246   }
4247 }
4248 
4249 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4250 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4251 
4252 class G1ParEvacuateFollowersClosure : public VoidClosure {
4253 protected:
4254   G1CollectedHeap*              _g1h;
4255   G1ParScanThreadState*         _par_scan_state;
4256   RefToScanQueueSet*            _queues;
4257   ParallelTaskTerminator*       _terminator;
4258 
4259   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4260   RefToScanQueueSet*      queues()         { return _queues; }
4261   ParallelTaskTerminator* terminator()     { return _terminator; }
4262 
4263 public:
4264   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4265                                 G1ParScanThreadState* par_scan_state,
4266                                 RefToScanQueueSet* queues,
4267                                 ParallelTaskTerminator* terminator)
4268     : _g1h(g1h), _par_scan_state(par_scan_state),
4269       _queues(queues), _terminator(terminator) {}
4270 
4271   void do_void();
4272 
4273 private:
4274   inline bool offer_termination();
4275 };
4276 
4277 bool G1ParEvacuateFollowersClosure::offer_termination() {
4278   G1ParScanThreadState* const pss = par_scan_state();
4279   pss->start_term_time();
4280   const bool res = terminator()->offer_termination();
4281   pss->end_term_time();
4282   return res;
4283 }
4284 
4285 void G1ParEvacuateFollowersClosure::do_void() {
4286   G1ParScanThreadState* const pss = par_scan_state();
4287   pss->trim_queue();
4288   do {
4289     pss->steal_and_trim_queue(queues());
4290   } while (!offer_termination());
4291 }
4292 
4293 class G1KlassScanClosure : public KlassClosure {
4294  G1ParCopyHelper* _closure;
4295  bool             _process_only_dirty;
4296  int              _count;
4297  public:
4298   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4299       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4300   void do_klass(Klass* klass) {
4301     // If the klass has not been dirtied we know that there's
4302     // no references into  the young gen and we can skip it.
4303    if (!_process_only_dirty || klass->has_modified_oops()) {
4304       // Clean the klass since we're going to scavenge all the metadata.
4305       klass->clear_modified_oops();
4306 
4307       // Tell the closure that this klass is the Klass to scavenge
4308       // and is the one to dirty if oops are left pointing into the young gen.
4309       _closure->set_scanned_klass(klass);
4310 
4311       klass->oops_do(_closure);
4312 
4313       _closure->set_scanned_klass(NULL);
4314     }
4315     _count++;
4316   }
4317 };
4318 
4319 class G1ParTask : public AbstractGangTask {
4320 protected:
4321   G1CollectedHeap*       _g1h;
4322   RefToScanQueueSet      *_queues;
4323   G1RootProcessor*       _root_processor;
4324   ParallelTaskTerminator _terminator;
4325   uint _n_workers;
4326 
4327   Mutex _stats_lock;
4328   Mutex* stats_lock() { return &_stats_lock; }
4329 
4330 public:
4331   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4332     : AbstractGangTask("G1 collection"),
4333       _g1h(g1h),
4334       _queues(task_queues),
4335       _root_processor(root_processor),
4336       _terminator(0, _queues),
4337       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4338   {}
4339 
4340   RefToScanQueueSet* queues() { return _queues; }
4341 
4342   RefToScanQueue *work_queue(int i) {
4343     return queues()->queue(i);
4344   }
4345 
4346   ParallelTaskTerminator* terminator() { return &_terminator; }
4347 
4348   virtual void set_for_termination(int active_workers) {
4349     _root_processor->set_num_workers(active_workers);
4350     terminator()->reset_for_reuse(active_workers);
4351     _n_workers = active_workers;
4352   }
4353 
4354   // Helps out with CLD processing.
4355   //
4356   // During InitialMark we need to:
4357   // 1) Scavenge all CLDs for the young GC.
4358   // 2) Mark all objects directly reachable from strong CLDs.
4359   template <G1Mark do_mark_object>
4360   class G1CLDClosure : public CLDClosure {
4361     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4362     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4363     G1KlassScanClosure                                _klass_in_cld_closure;
4364     bool                                              _claim;
4365 
4366    public:
4367     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4368                  bool only_young, bool claim)
4369         : _oop_closure(oop_closure),
4370           _oop_in_klass_closure(oop_closure->g1(),
4371                                 oop_closure->pss(),
4372                                 oop_closure->rp()),
4373           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4374           _claim(claim) {
4375 
4376     }
4377 
4378     void do_cld(ClassLoaderData* cld) {
4379       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4380     }
4381   };
4382 
4383   void work(uint worker_id) {
4384     if (worker_id >= _n_workers) return;  // no work needed this round
4385 
4386     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4387 
4388     {
4389       ResourceMark rm;
4390       HandleMark   hm;
4391 
4392       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4393 
4394       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4395       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4396 
4397       pss.set_evac_failure_closure(&evac_failure_cl);
4398 
4399       bool only_young = _g1h->g1_policy()->gcs_are_young();
4400 
4401       // Non-IM young GC.
4402       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4403       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4404                                                                                only_young, // Only process dirty klasses.
4405                                                                                false);     // No need to claim CLDs.
4406       // IM young GC.
4407       //    Strong roots closures.
4408       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4409       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4410                                                                                false, // Process all klasses.
4411                                                                                true); // Need to claim CLDs.
4412       //    Weak roots closures.
4413       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4414       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4415                                                                                     false, // Process all klasses.
4416                                                                                     true); // Need to claim CLDs.
4417 
4418       OopClosure* strong_root_cl;
4419       OopClosure* weak_root_cl;
4420       CLDClosure* strong_cld_cl;
4421       CLDClosure* weak_cld_cl;
4422 
4423       bool trace_metadata = false;
4424 
4425       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4426         // We also need to mark copied objects.
4427         strong_root_cl = &scan_mark_root_cl;
4428         strong_cld_cl  = &scan_mark_cld_cl;
4429         if (ClassUnloadingWithConcurrentMark) {
4430           weak_root_cl = &scan_mark_weak_root_cl;
4431           weak_cld_cl  = &scan_mark_weak_cld_cl;
4432           trace_metadata = true;
4433         } else {
4434           weak_root_cl = &scan_mark_root_cl;
4435           weak_cld_cl  = &scan_mark_cld_cl;
4436         }
4437       } else {
4438         strong_root_cl = &scan_only_root_cl;
4439         weak_root_cl   = &scan_only_root_cl;
4440         strong_cld_cl  = &scan_only_cld_cl;
4441         weak_cld_cl    = &scan_only_cld_cl;
4442       }
4443 
4444       pss.start_strong_roots();
4445 
4446       _root_processor->evacuate_roots(strong_root_cl,
4447                                       weak_root_cl,
4448                                       strong_cld_cl,
4449                                       weak_cld_cl,
4450                                       trace_metadata,
4451                                       worker_id);
4452 
4453       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4454       _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4455                                             weak_root_cl,
4456                                             worker_id);
4457       pss.end_strong_roots();
4458 
4459       {
4460         double start = os::elapsedTime();
4461         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4462         evac.do_void();
4463         double elapsed_sec = os::elapsedTime() - start;
4464         double term_sec = pss.term_time();
4465         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4466         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4467         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4468       }
4469       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4470       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4471 
4472       if (PrintTerminationStats) {
4473         MutexLocker x(stats_lock());
4474         pss.print_termination_stats(worker_id);
4475       }
4476 
4477       assert(pss.queue_is_empty(), "should be empty");
4478 
4479       // Close the inner scope so that the ResourceMark and HandleMark
4480       // destructors are executed here and are included as part of the
4481       // "GC Worker Time".
4482     }
4483     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4484   }
4485 };
4486 
4487 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4488 private:
4489   BoolObjectClosure* _is_alive;
4490   int _initial_string_table_size;
4491   int _initial_symbol_table_size;
4492 
4493   bool  _process_strings;
4494   int _strings_processed;
4495   int _strings_removed;
4496 
4497   bool  _process_symbols;
4498   int _symbols_processed;
4499   int _symbols_removed;
4500 
4501 public:
4502   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4503     AbstractGangTask("String/Symbol Unlinking"),
4504     _is_alive(is_alive),
4505     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4506     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4507 
4508     _initial_string_table_size = StringTable::the_table()->table_size();
4509     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4510     if (process_strings) {
4511       StringTable::clear_parallel_claimed_index();
4512     }
4513     if (process_symbols) {
4514       SymbolTable::clear_parallel_claimed_index();
4515     }
4516   }
4517 
4518   ~G1StringSymbolTableUnlinkTask() {
4519     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4520               err_msg("claim value %d after unlink less than initial string table size %d",
4521                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4522     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4523               err_msg("claim value %d after unlink less than initial symbol table size %d",
4524                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4525 
4526     if (G1TraceStringSymbolTableScrubbing) {
4527       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4528                              "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4529                              "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4530                              strings_processed(), strings_removed(),
4531                              symbols_processed(), symbols_removed());
4532     }
4533   }
4534 
4535   void work(uint worker_id) {
4536     int strings_processed = 0;
4537     int strings_removed = 0;
4538     int symbols_processed = 0;
4539     int symbols_removed = 0;
4540     if (_process_strings) {
4541       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4542       Atomic::add(strings_processed, &_strings_processed);
4543       Atomic::add(strings_removed, &_strings_removed);
4544     }
4545     if (_process_symbols) {
4546       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4547       Atomic::add(symbols_processed, &_symbols_processed);
4548       Atomic::add(symbols_removed, &_symbols_removed);
4549     }
4550   }
4551 
4552   size_t strings_processed() const { return (size_t)_strings_processed; }
4553   size_t strings_removed()   const { return (size_t)_strings_removed; }
4554 
4555   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4556   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4557 };
4558 
4559 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4560 private:
4561   static Monitor* _lock;
4562 
4563   BoolObjectClosure* const _is_alive;
4564   const bool               _unloading_occurred;
4565   const uint               _num_workers;
4566 
4567   // Variables used to claim nmethods.
4568   nmethod* _first_nmethod;
4569   volatile nmethod* _claimed_nmethod;
4570 
4571   // The list of nmethods that need to be processed by the second pass.
4572   volatile nmethod* _postponed_list;
4573   volatile uint     _num_entered_barrier;
4574 
4575  public:
4576   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4577       _is_alive(is_alive),
4578       _unloading_occurred(unloading_occurred),
4579       _num_workers(num_workers),
4580       _first_nmethod(NULL),
4581       _claimed_nmethod(NULL),
4582       _postponed_list(NULL),
4583       _num_entered_barrier(0)
4584   {
4585     nmethod::increase_unloading_clock();
4586     // Get first alive nmethod
4587     NMethodIterator iter = NMethodIterator();
4588     if(iter.next_alive()) {
4589       _first_nmethod = iter.method();
4590     }
4591     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4592   }
4593 
4594   ~G1CodeCacheUnloadingTask() {
4595     CodeCache::verify_clean_inline_caches();
4596 
4597     CodeCache::set_needs_cache_clean(false);
4598     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4599 
4600     CodeCache::verify_icholder_relocations();
4601   }
4602 
4603  private:
4604   void add_to_postponed_list(nmethod* nm) {
4605       nmethod* old;
4606       do {
4607         old = (nmethod*)_postponed_list;
4608         nm->set_unloading_next(old);
4609       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4610   }
4611 
4612   void clean_nmethod(nmethod* nm) {
4613     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4614 
4615     if (postponed) {
4616       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4617       add_to_postponed_list(nm);
4618     }
4619 
4620     // Mark that this thread has been cleaned/unloaded.
4621     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4622     nm->set_unloading_clock(nmethod::global_unloading_clock());
4623   }
4624 
4625   void clean_nmethod_postponed(nmethod* nm) {
4626     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4627   }
4628 
4629   static const int MaxClaimNmethods = 16;
4630 
4631   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4632     nmethod* first;
4633     NMethodIterator last;
4634 
4635     do {
4636       *num_claimed_nmethods = 0;
4637 
4638       first = (nmethod*)_claimed_nmethod;
4639       last = NMethodIterator(first);
4640 
4641       if (first != NULL) {
4642 
4643         for (int i = 0; i < MaxClaimNmethods; i++) {
4644           if (!last.next_alive()) {
4645             break;
4646           }
4647           claimed_nmethods[i] = last.method();
4648           (*num_claimed_nmethods)++;
4649         }
4650       }
4651 
4652     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4653   }
4654 
4655   nmethod* claim_postponed_nmethod() {
4656     nmethod* claim;
4657     nmethod* next;
4658 
4659     do {
4660       claim = (nmethod*)_postponed_list;
4661       if (claim == NULL) {
4662         return NULL;
4663       }
4664 
4665       next = claim->unloading_next();
4666 
4667     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4668 
4669     return claim;
4670   }
4671 
4672  public:
4673   // Mark that we're done with the first pass of nmethod cleaning.
4674   void barrier_mark(uint worker_id) {
4675     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4676     _num_entered_barrier++;
4677     if (_num_entered_barrier == _num_workers) {
4678       ml.notify_all();
4679     }
4680   }
4681 
4682   // See if we have to wait for the other workers to
4683   // finish their first-pass nmethod cleaning work.
4684   void barrier_wait(uint worker_id) {
4685     if (_num_entered_barrier < _num_workers) {
4686       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4687       while (_num_entered_barrier < _num_workers) {
4688           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4689       }
4690     }
4691   }
4692 
4693   // Cleaning and unloading of nmethods. Some work has to be postponed
4694   // to the second pass, when we know which nmethods survive.
4695   void work_first_pass(uint worker_id) {
4696     // The first nmethods is claimed by the first worker.
4697     if (worker_id == 0 && _first_nmethod != NULL) {
4698       clean_nmethod(_first_nmethod);
4699       _first_nmethod = NULL;
4700     }
4701 
4702     int num_claimed_nmethods;
4703     nmethod* claimed_nmethods[MaxClaimNmethods];
4704 
4705     while (true) {
4706       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4707 
4708       if (num_claimed_nmethods == 0) {
4709         break;
4710       }
4711 
4712       for (int i = 0; i < num_claimed_nmethods; i++) {
4713         clean_nmethod(claimed_nmethods[i]);
4714       }
4715     }
4716   }
4717 
4718   void work_second_pass(uint worker_id) {
4719     nmethod* nm;
4720     // Take care of postponed nmethods.
4721     while ((nm = claim_postponed_nmethod()) != NULL) {
4722       clean_nmethod_postponed(nm);
4723     }
4724   }
4725 };
4726 
4727 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4728 
4729 class G1KlassCleaningTask : public StackObj {
4730   BoolObjectClosure*                      _is_alive;
4731   volatile jint                           _clean_klass_tree_claimed;
4732   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4733 
4734  public:
4735   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4736       _is_alive(is_alive),
4737       _clean_klass_tree_claimed(0),
4738       _klass_iterator() {
4739   }
4740 
4741  private:
4742   bool claim_clean_klass_tree_task() {
4743     if (_clean_klass_tree_claimed) {
4744       return false;
4745     }
4746 
4747     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4748   }
4749 
4750   InstanceKlass* claim_next_klass() {
4751     Klass* klass;
4752     do {
4753       klass =_klass_iterator.next_klass();
4754     } while (klass != NULL && !klass->oop_is_instance());
4755 
4756     return (InstanceKlass*)klass;
4757   }
4758 
4759 public:
4760 
4761   void clean_klass(InstanceKlass* ik) {
4762     ik->clean_implementors_list(_is_alive);
4763     ik->clean_method_data(_is_alive);
4764 
4765     // G1 specific cleanup work that has
4766     // been moved here to be done in parallel.
4767     ik->clean_dependent_nmethods();
4768   }
4769 
4770   void work() {
4771     ResourceMark rm;
4772 
4773     // One worker will clean the subklass/sibling klass tree.
4774     if (claim_clean_klass_tree_task()) {
4775       Klass::clean_subklass_tree(_is_alive);
4776     }
4777 
4778     // All workers will help cleaning the classes,
4779     InstanceKlass* klass;
4780     while ((klass = claim_next_klass()) != NULL) {
4781       clean_klass(klass);
4782     }
4783   }
4784 };
4785 
4786 // To minimize the remark pause times, the tasks below are done in parallel.
4787 class G1ParallelCleaningTask : public AbstractGangTask {
4788 private:
4789   G1StringSymbolTableUnlinkTask _string_symbol_task;
4790   G1CodeCacheUnloadingTask      _code_cache_task;
4791   G1KlassCleaningTask           _klass_cleaning_task;
4792 
4793 public:
4794   // The constructor is run in the VMThread.
4795   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4796       AbstractGangTask("Parallel Cleaning"),
4797       _string_symbol_task(is_alive, process_strings, process_symbols),
4798       _code_cache_task(num_workers, is_alive, unloading_occurred),
4799       _klass_cleaning_task(is_alive) {
4800   }
4801 
4802   // The parallel work done by all worker threads.
4803   void work(uint worker_id) {
4804     // Do first pass of code cache cleaning.
4805     _code_cache_task.work_first_pass(worker_id);
4806 
4807     // Let the threads mark that the first pass is done.
4808     _code_cache_task.barrier_mark(worker_id);
4809 
4810     // Clean the Strings and Symbols.
4811     _string_symbol_task.work(worker_id);
4812 
4813     // Wait for all workers to finish the first code cache cleaning pass.
4814     _code_cache_task.barrier_wait(worker_id);
4815 
4816     // Do the second code cache cleaning work, which realize on
4817     // the liveness information gathered during the first pass.
4818     _code_cache_task.work_second_pass(worker_id);
4819 
4820     // Clean all klasses that were not unloaded.
4821     _klass_cleaning_task.work();
4822   }
4823 };
4824 
4825 
4826 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4827                                         bool process_strings,
4828                                         bool process_symbols,
4829                                         bool class_unloading_occurred) {
4830   uint n_workers = workers()->active_workers();
4831 
4832   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4833                                         n_workers, class_unloading_occurred);
4834   set_par_threads(n_workers);
4835   workers()->run_task(&g1_unlink_task);
4836   set_par_threads(0);
4837 }
4838 
4839 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4840                                                      bool process_strings, bool process_symbols) {
4841   {
4842     uint n_workers = _g1h->workers()->active_workers();
4843     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4844     set_par_threads(n_workers);
4845     workers()->run_task(&g1_unlink_task);
4846     set_par_threads(0);
4847   }
4848 
4849   if (G1StringDedup::is_enabled()) {
4850     G1StringDedup::unlink(is_alive);
4851   }
4852 }
4853 
4854 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4855  private:
4856   DirtyCardQueueSet* _queue;
4857  public:
4858   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4859 
4860   virtual void work(uint worker_id) {
4861     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4862     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4863 
4864     RedirtyLoggedCardTableEntryClosure cl;
4865     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4866 
4867     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4868   }
4869 };
4870 
4871 void G1CollectedHeap::redirty_logged_cards() {
4872   double redirty_logged_cards_start = os::elapsedTime();
4873 
4874   uint n_workers = _g1h->workers()->active_workers();
4875 
4876   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4877   dirty_card_queue_set().reset_for_par_iteration();
4878   set_par_threads(n_workers);
4879   workers()->run_task(&redirty_task);
4880   set_par_threads(0);
4881 
4882   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4883   dcq.merge_bufferlists(&dirty_card_queue_set());
4884   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4885 
4886   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4887 }
4888 
4889 // Weak Reference Processing support
4890 
4891 // An always "is_alive" closure that is used to preserve referents.
4892 // If the object is non-null then it's alive.  Used in the preservation
4893 // of referent objects that are pointed to by reference objects
4894 // discovered by the CM ref processor.
4895 class G1AlwaysAliveClosure: public BoolObjectClosure {
4896   G1CollectedHeap* _g1;
4897 public:
4898   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4899   bool do_object_b(oop p) {
4900     if (p != NULL) {
4901       return true;
4902     }
4903     return false;
4904   }
4905 };
4906 
4907 bool G1STWIsAliveClosure::do_object_b(oop p) {
4908   // An object is reachable if it is outside the collection set,
4909   // or is inside and copied.
4910   return !_g1->obj_in_cs(p) || p->is_forwarded();
4911 }
4912 
4913 // Non Copying Keep Alive closure
4914 class G1KeepAliveClosure: public OopClosure {
4915   G1CollectedHeap* _g1;
4916 public:
4917   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4918   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4919   void do_oop(oop* p) {
4920     oop obj = *p;
4921     assert(obj != NULL, "the caller should have filtered out NULL values");
4922 
4923     const InCSetState cset_state = _g1->in_cset_state(obj);
4924     if (!cset_state.is_in_cset_or_humongous()) {
4925       return;
4926     }
4927     if (cset_state.is_in_cset()) {
4928       assert( obj->is_forwarded(), "invariant" );
4929       *p = obj->forwardee();
4930     } else {
4931       assert(!obj->is_forwarded(), "invariant" );
4932       assert(cset_state.is_humongous(),
4933              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4934       _g1->set_humongous_is_live(obj);
4935     }
4936   }
4937 };
4938 
4939 // Copying Keep Alive closure - can be called from both
4940 // serial and parallel code as long as different worker
4941 // threads utilize different G1ParScanThreadState instances
4942 // and different queues.
4943 
4944 class G1CopyingKeepAliveClosure: public OopClosure {
4945   G1CollectedHeap*         _g1h;
4946   OopClosure*              _copy_non_heap_obj_cl;
4947   G1ParScanThreadState*    _par_scan_state;
4948 
4949 public:
4950   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4951                             OopClosure* non_heap_obj_cl,
4952                             G1ParScanThreadState* pss):
4953     _g1h(g1h),
4954     _copy_non_heap_obj_cl(non_heap_obj_cl),
4955     _par_scan_state(pss)
4956   {}
4957 
4958   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4959   virtual void do_oop(      oop* p) { do_oop_work(p); }
4960 
4961   template <class T> void do_oop_work(T* p) {
4962     oop obj = oopDesc::load_decode_heap_oop(p);
4963 
4964     if (_g1h->is_in_cset_or_humongous(obj)) {
4965       // If the referent object has been forwarded (either copied
4966       // to a new location or to itself in the event of an
4967       // evacuation failure) then we need to update the reference
4968       // field and, if both reference and referent are in the G1
4969       // heap, update the RSet for the referent.
4970       //
4971       // If the referent has not been forwarded then we have to keep
4972       // it alive by policy. Therefore we have copy the referent.
4973       //
4974       // If the reference field is in the G1 heap then we can push
4975       // on the PSS queue. When the queue is drained (after each
4976       // phase of reference processing) the object and it's followers
4977       // will be copied, the reference field set to point to the
4978       // new location, and the RSet updated. Otherwise we need to
4979       // use the the non-heap or metadata closures directly to copy
4980       // the referent object and update the pointer, while avoiding
4981       // updating the RSet.
4982 
4983       if (_g1h->is_in_g1_reserved(p)) {
4984         _par_scan_state->push_on_queue(p);
4985       } else {
4986         assert(!Metaspace::contains((const void*)p),
4987                err_msg("Unexpectedly found a pointer from metadata: "
4988                               PTR_FORMAT, p));
4989         _copy_non_heap_obj_cl->do_oop(p);
4990       }
4991     }
4992   }
4993 };
4994 
4995 // Serial drain queue closure. Called as the 'complete_gc'
4996 // closure for each discovered list in some of the
4997 // reference processing phases.
4998 
4999 class G1STWDrainQueueClosure: public VoidClosure {
5000 protected:
5001   G1CollectedHeap* _g1h;
5002   G1ParScanThreadState* _par_scan_state;
5003 
5004   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5005 
5006 public:
5007   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5008     _g1h(g1h),
5009     _par_scan_state(pss)
5010   { }
5011 
5012   void do_void() {
5013     G1ParScanThreadState* const pss = par_scan_state();
5014     pss->trim_queue();
5015   }
5016 };
5017 
5018 // Parallel Reference Processing closures
5019 
5020 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5021 // processing during G1 evacuation pauses.
5022 
5023 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5024 private:
5025   G1CollectedHeap*   _g1h;
5026   RefToScanQueueSet* _queues;
5027   FlexibleWorkGang*  _workers;
5028   int                _active_workers;
5029 
5030 public:
5031   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5032                         FlexibleWorkGang* workers,
5033                         RefToScanQueueSet *task_queues,
5034                         int n_workers) :
5035     _g1h(g1h),
5036     _queues(task_queues),
5037     _workers(workers),
5038     _active_workers(n_workers)
5039   {
5040     assert(n_workers > 0, "shouldn't call this otherwise");
5041   }
5042 
5043   // Executes the given task using concurrent marking worker threads.
5044   virtual void execute(ProcessTask& task);
5045   virtual void execute(EnqueueTask& task);
5046 };
5047 
5048 // Gang task for possibly parallel reference processing
5049 
5050 class G1STWRefProcTaskProxy: public AbstractGangTask {
5051   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5052   ProcessTask&     _proc_task;
5053   G1CollectedHeap* _g1h;
5054   RefToScanQueueSet *_task_queues;
5055   ParallelTaskTerminator* _terminator;
5056 
5057 public:
5058   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5059                      G1CollectedHeap* g1h,
5060                      RefToScanQueueSet *task_queues,
5061                      ParallelTaskTerminator* terminator) :
5062     AbstractGangTask("Process reference objects in parallel"),
5063     _proc_task(proc_task),
5064     _g1h(g1h),
5065     _task_queues(task_queues),
5066     _terminator(terminator)
5067   {}
5068 
5069   virtual void work(uint worker_id) {
5070     // The reference processing task executed by a single worker.
5071     ResourceMark rm;
5072     HandleMark   hm;
5073 
5074     G1STWIsAliveClosure is_alive(_g1h);
5075 
5076     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5077     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5078 
5079     pss.set_evac_failure_closure(&evac_failure_cl);
5080 
5081     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5082 
5083     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5084 
5085     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5086 
5087     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5088       // We also need to mark copied objects.
5089       copy_non_heap_cl = &copy_mark_non_heap_cl;
5090     }
5091 
5092     // Keep alive closure.
5093     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5094 
5095     // Complete GC closure
5096     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5097 
5098     // Call the reference processing task's work routine.
5099     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5100 
5101     // Note we cannot assert that the refs array is empty here as not all
5102     // of the processing tasks (specifically phase2 - pp2_work) execute
5103     // the complete_gc closure (which ordinarily would drain the queue) so
5104     // the queue may not be empty.
5105   }
5106 };
5107 
5108 // Driver routine for parallel reference processing.
5109 // Creates an instance of the ref processing gang
5110 // task and has the worker threads execute it.
5111 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5112   assert(_workers != NULL, "Need parallel worker threads.");
5113 
5114   ParallelTaskTerminator terminator(_active_workers, _queues);
5115   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5116 
5117   _g1h->set_par_threads(_active_workers);
5118   _workers->run_task(&proc_task_proxy);
5119   _g1h->set_par_threads(0);
5120 }
5121 
5122 // Gang task for parallel reference enqueueing.
5123 
5124 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5125   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5126   EnqueueTask& _enq_task;
5127 
5128 public:
5129   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5130     AbstractGangTask("Enqueue reference objects in parallel"),
5131     _enq_task(enq_task)
5132   { }
5133 
5134   virtual void work(uint worker_id) {
5135     _enq_task.work(worker_id);
5136   }
5137 };
5138 
5139 // Driver routine for parallel reference enqueueing.
5140 // Creates an instance of the ref enqueueing gang
5141 // task and has the worker threads execute it.
5142 
5143 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5144   assert(_workers != NULL, "Need parallel worker threads.");
5145 
5146   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5147 
5148   _g1h->set_par_threads(_active_workers);
5149   _workers->run_task(&enq_task_proxy);
5150   _g1h->set_par_threads(0);
5151 }
5152 
5153 // End of weak reference support closures
5154 
5155 // Abstract task used to preserve (i.e. copy) any referent objects
5156 // that are in the collection set and are pointed to by reference
5157 // objects discovered by the CM ref processor.
5158 
5159 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5160 protected:
5161   G1CollectedHeap* _g1h;
5162   RefToScanQueueSet      *_queues;
5163   ParallelTaskTerminator _terminator;
5164   uint _n_workers;
5165 
5166 public:
5167   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5168     AbstractGangTask("ParPreserveCMReferents"),
5169     _g1h(g1h),
5170     _queues(task_queues),
5171     _terminator(workers, _queues),
5172     _n_workers(workers)
5173   { }
5174 
5175   void work(uint worker_id) {
5176     ResourceMark rm;
5177     HandleMark   hm;
5178 
5179     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5180     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5181 
5182     pss.set_evac_failure_closure(&evac_failure_cl);
5183 
5184     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5185 
5186     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5187 
5188     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5189 
5190     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5191 
5192     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5193       // We also need to mark copied objects.
5194       copy_non_heap_cl = &copy_mark_non_heap_cl;
5195     }
5196 
5197     // Is alive closure
5198     G1AlwaysAliveClosure always_alive(_g1h);
5199 
5200     // Copying keep alive closure. Applied to referent objects that need
5201     // to be copied.
5202     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5203 
5204     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5205 
5206     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5207     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5208 
5209     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5210     // So this must be true - but assert just in case someone decides to
5211     // change the worker ids.
5212     assert(worker_id < limit, "sanity");
5213     assert(!rp->discovery_is_atomic(), "check this code");
5214 
5215     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5216     for (uint idx = worker_id; idx < limit; idx += stride) {
5217       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5218 
5219       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5220       while (iter.has_next()) {
5221         // Since discovery is not atomic for the CM ref processor, we
5222         // can see some null referent objects.
5223         iter.load_ptrs(DEBUG_ONLY(true));
5224         oop ref = iter.obj();
5225 
5226         // This will filter nulls.
5227         if (iter.is_referent_alive()) {
5228           iter.make_referent_alive();
5229         }
5230         iter.move_to_next();
5231       }
5232     }
5233 
5234     // Drain the queue - which may cause stealing
5235     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5236     drain_queue.do_void();
5237     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5238     assert(pss.queue_is_empty(), "should be");
5239   }
5240 };
5241 
5242 // Weak Reference processing during an evacuation pause (part 1).
5243 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5244   double ref_proc_start = os::elapsedTime();
5245 
5246   ReferenceProcessor* rp = _ref_processor_stw;
5247   assert(rp->discovery_enabled(), "should have been enabled");
5248 
5249   // Any reference objects, in the collection set, that were 'discovered'
5250   // by the CM ref processor should have already been copied (either by
5251   // applying the external root copy closure to the discovered lists, or
5252   // by following an RSet entry).
5253   //
5254   // But some of the referents, that are in the collection set, that these
5255   // reference objects point to may not have been copied: the STW ref
5256   // processor would have seen that the reference object had already
5257   // been 'discovered' and would have skipped discovering the reference,
5258   // but would not have treated the reference object as a regular oop.
5259   // As a result the copy closure would not have been applied to the
5260   // referent object.
5261   //
5262   // We need to explicitly copy these referent objects - the references
5263   // will be processed at the end of remarking.
5264   //
5265   // We also need to do this copying before we process the reference
5266   // objects discovered by the STW ref processor in case one of these
5267   // referents points to another object which is also referenced by an
5268   // object discovered by the STW ref processor.
5269 
5270   assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5271 
5272   set_par_threads(no_of_gc_workers);
5273   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5274                                                  no_of_gc_workers,
5275                                                  _task_queues);
5276 
5277   workers()->run_task(&keep_cm_referents);
5278 
5279   set_par_threads(0);
5280 
5281   // Closure to test whether a referent is alive.
5282   G1STWIsAliveClosure is_alive(this);
5283 
5284   // Even when parallel reference processing is enabled, the processing
5285   // of JNI refs is serial and performed serially by the current thread
5286   // rather than by a worker. The following PSS will be used for processing
5287   // JNI refs.
5288 
5289   // Use only a single queue for this PSS.
5290   G1ParScanThreadState            pss(this, 0, NULL);
5291 
5292   // We do not embed a reference processor in the copying/scanning
5293   // closures while we're actually processing the discovered
5294   // reference objects.
5295   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5296 
5297   pss.set_evac_failure_closure(&evac_failure_cl);
5298 
5299   assert(pss.queue_is_empty(), "pre-condition");
5300 
5301   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5302 
5303   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5304 
5305   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5306 
5307   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5308     // We also need to mark copied objects.
5309     copy_non_heap_cl = &copy_mark_non_heap_cl;
5310   }
5311 
5312   // Keep alive closure.
5313   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5314 
5315   // Serial Complete GC closure
5316   G1STWDrainQueueClosure drain_queue(this, &pss);
5317 
5318   // Setup the soft refs policy...
5319   rp->setup_policy(false);
5320 
5321   ReferenceProcessorStats stats;
5322   if (!rp->processing_is_mt()) {
5323     // Serial reference processing...
5324     stats = rp->process_discovered_references(&is_alive,
5325                                               &keep_alive,
5326                                               &drain_queue,
5327                                               NULL,
5328                                               _gc_timer_stw,
5329                                               _gc_tracer_stw->gc_id());
5330   } else {
5331     // Parallel reference processing
5332     assert(rp->num_q() == no_of_gc_workers, "sanity");
5333     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5334 
5335     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5336     stats = rp->process_discovered_references(&is_alive,
5337                                               &keep_alive,
5338                                               &drain_queue,
5339                                               &par_task_executor,
5340                                               _gc_timer_stw,
5341                                               _gc_tracer_stw->gc_id());
5342   }
5343 
5344   _gc_tracer_stw->report_gc_reference_stats(stats);
5345 
5346   // We have completed copying any necessary live referent objects.
5347   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5348 
5349   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5350   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5351 }
5352 
5353 // Weak Reference processing during an evacuation pause (part 2).
5354 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5355   double ref_enq_start = os::elapsedTime();
5356 
5357   ReferenceProcessor* rp = _ref_processor_stw;
5358   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5359 
5360   // Now enqueue any remaining on the discovered lists on to
5361   // the pending list.
5362   if (!rp->processing_is_mt()) {
5363     // Serial reference processing...
5364     rp->enqueue_discovered_references();
5365   } else {
5366     // Parallel reference enqueueing
5367 
5368     assert(no_of_gc_workers == workers()->active_workers(),
5369            "Need to reset active workers");
5370     assert(rp->num_q() == no_of_gc_workers, "sanity");
5371     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5372 
5373     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5374     rp->enqueue_discovered_references(&par_task_executor);
5375   }
5376 
5377   rp->verify_no_references_recorded();
5378   assert(!rp->discovery_enabled(), "should have been disabled");
5379 
5380   // FIXME
5381   // CM's reference processing also cleans up the string and symbol tables.
5382   // Should we do that here also? We could, but it is a serial operation
5383   // and could significantly increase the pause time.
5384 
5385   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5386   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5387 }
5388 
5389 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5390   _expand_heap_after_alloc_failure = true;
5391   _evacuation_failed = false;
5392 
5393   // Should G1EvacuationFailureALot be in effect for this GC?
5394   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5395 
5396   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5397 
5398   // Disable the hot card cache.
5399   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5400   hot_card_cache->reset_hot_cache_claimed_index();
5401   hot_card_cache->set_use_cache(false);
5402 
5403   const uint n_workers = workers()->active_workers();
5404   assert(UseDynamicNumberOfGCThreads ||
5405          n_workers == workers()->total_workers(),
5406          "If not dynamic should be using all the  workers");
5407   set_par_threads(n_workers);
5408 
5409 
5410   init_for_evac_failure(NULL);
5411 
5412   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5413   double start_par_time_sec = os::elapsedTime();
5414   double end_par_time_sec;
5415 
5416   {
5417     G1RootProcessor root_processor(this);
5418     G1ParTask g1_par_task(this, _task_queues, &root_processor);
5419     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5420     if (g1_policy()->during_initial_mark_pause()) {
5421       ClassLoaderDataGraph::clear_claimed_marks();
5422     }
5423 
5424      // The individual threads will set their evac-failure closures.
5425      if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5426      // These tasks use ShareHeap::_process_strong_tasks
5427      assert(UseDynamicNumberOfGCThreads ||
5428             workers()->active_workers() == workers()->total_workers(),
5429             "If not dynamic should be using all the  workers");
5430     workers()->run_task(&g1_par_task);
5431     end_par_time_sec = os::elapsedTime();
5432 
5433     // Closing the inner scope will execute the destructor
5434     // for the G1RootProcessor object. We record the current
5435     // elapsed time before closing the scope so that time
5436     // taken for the destructor is NOT included in the
5437     // reported parallel time.
5438   }
5439 
5440   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5441 
5442   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5443   phase_times->record_par_time(par_time_ms);
5444 
5445   double code_root_fixup_time_ms =
5446         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5447   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5448 
5449   set_par_threads(0);
5450 
5451   // Process any discovered reference objects - we have
5452   // to do this _before_ we retire the GC alloc regions
5453   // as we may have to copy some 'reachable' referent
5454   // objects (and their reachable sub-graphs) that were
5455   // not copied during the pause.
5456   process_discovered_references(n_workers);
5457 
5458   if (G1StringDedup::is_enabled()) {
5459     double fixup_start = os::elapsedTime();
5460 
5461     G1STWIsAliveClosure is_alive(this);
5462     G1KeepAliveClosure keep_alive(this);
5463     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5464 
5465     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5466     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5467   }
5468 
5469   _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5470   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5471 
5472   // Reset and re-enable the hot card cache.
5473   // Note the counts for the cards in the regions in the
5474   // collection set are reset when the collection set is freed.
5475   hot_card_cache->reset_hot_cache();
5476   hot_card_cache->set_use_cache(true);
5477 
5478   purge_code_root_memory();
5479 
5480   finalize_for_evac_failure();
5481 
5482   if (evacuation_failed()) {
5483     remove_self_forwarding_pointers();
5484 
5485     // Reset the G1EvacuationFailureALot counters and flags
5486     // Note: the values are reset only when an actual
5487     // evacuation failure occurs.
5488     NOT_PRODUCT(reset_evacuation_should_fail();)
5489   }
5490 
5491   // Enqueue any remaining references remaining on the STW
5492   // reference processor's discovered lists. We need to do
5493   // this after the card table is cleaned (and verified) as
5494   // the act of enqueueing entries on to the pending list
5495   // will log these updates (and dirty their associated
5496   // cards). We need these updates logged to update any
5497   // RSets.
5498   enqueue_discovered_references(n_workers);
5499 
5500   redirty_logged_cards();
5501   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5502 }
5503 
5504 void G1CollectedHeap::free_region(HeapRegion* hr,
5505                                   FreeRegionList* free_list,
5506                                   bool par,
5507                                   bool locked) {
5508   assert(!hr->is_free(), "the region should not be free");
5509   assert(!hr->is_empty(), "the region should not be empty");
5510   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5511   assert(free_list != NULL, "pre-condition");
5512 
5513   if (G1VerifyBitmaps) {
5514     MemRegion mr(hr->bottom(), hr->end());
5515     concurrent_mark()->clearRangePrevBitmap(mr);
5516   }
5517 
5518   // Clear the card counts for this region.
5519   // Note: we only need to do this if the region is not young
5520   // (since we don't refine cards in young regions).
5521   if (!hr->is_young()) {
5522     _cg1r->hot_card_cache()->reset_card_counts(hr);
5523   }
5524   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5525   free_list->add_ordered(hr);
5526 }
5527 
5528 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5529                                      FreeRegionList* free_list,
5530                                      bool par) {
5531   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5532   assert(free_list != NULL, "pre-condition");
5533 
5534   size_t hr_capacity = hr->capacity();
5535   // We need to read this before we make the region non-humongous,
5536   // otherwise the information will be gone.
5537   uint last_index = hr->last_hc_index();
5538   hr->clear_humongous();
5539   free_region(hr, free_list, par);
5540 
5541   uint i = hr->hrm_index() + 1;
5542   while (i < last_index) {
5543     HeapRegion* curr_hr = region_at(i);
5544     assert(curr_hr->is_continues_humongous(), "invariant");
5545     curr_hr->clear_humongous();
5546     free_region(curr_hr, free_list, par);
5547     i += 1;
5548   }
5549 }
5550 
5551 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5552                                        const HeapRegionSetCount& humongous_regions_removed) {
5553   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5554     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5555     _old_set.bulk_remove(old_regions_removed);
5556     _humongous_set.bulk_remove(humongous_regions_removed);
5557   }
5558 
5559 }
5560 
5561 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5562   assert(list != NULL, "list can't be null");
5563   if (!list->is_empty()) {
5564     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5565     _hrm.insert_list_into_free_list(list);
5566   }
5567 }
5568 
5569 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5570   _allocator->decrease_used(bytes);
5571 }
5572 
5573 class G1ParCleanupCTTask : public AbstractGangTask {
5574   G1SATBCardTableModRefBS* _ct_bs;
5575   G1CollectedHeap* _g1h;
5576   HeapRegion* volatile _su_head;
5577 public:
5578   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5579                      G1CollectedHeap* g1h) :
5580     AbstractGangTask("G1 Par Cleanup CT Task"),
5581     _ct_bs(ct_bs), _g1h(g1h) { }
5582 
5583   void work(uint worker_id) {
5584     HeapRegion* r;
5585     while (r = _g1h->pop_dirty_cards_region()) {
5586       clear_cards(r);
5587     }
5588   }
5589 
5590   void clear_cards(HeapRegion* r) {
5591     // Cards of the survivors should have already been dirtied.
5592     if (!r->is_survivor()) {
5593       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5594     }
5595   }
5596 };
5597 
5598 #ifndef PRODUCT
5599 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5600   G1CollectedHeap* _g1h;
5601   G1SATBCardTableModRefBS* _ct_bs;
5602 public:
5603   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5604     : _g1h(g1h), _ct_bs(ct_bs) { }
5605   virtual bool doHeapRegion(HeapRegion* r) {
5606     if (r->is_survivor()) {
5607       _g1h->verify_dirty_region(r);
5608     } else {
5609       _g1h->verify_not_dirty_region(r);
5610     }
5611     return false;
5612   }
5613 };
5614 
5615 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5616   // All of the region should be clean.
5617   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5618   MemRegion mr(hr->bottom(), hr->end());
5619   ct_bs->verify_not_dirty_region(mr);
5620 }
5621 
5622 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5623   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5624   // dirty allocated blocks as they allocate them. The thread that
5625   // retires each region and replaces it with a new one will do a
5626   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5627   // not dirty that area (one less thing to have to do while holding
5628   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5629   // is dirty.
5630   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5631   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5632   if (hr->is_young()) {
5633     ct_bs->verify_g1_young_region(mr);
5634   } else {
5635     ct_bs->verify_dirty_region(mr);
5636   }
5637 }
5638 
5639 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5640   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5641   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5642     verify_dirty_region(hr);
5643   }
5644 }
5645 
5646 void G1CollectedHeap::verify_dirty_young_regions() {
5647   verify_dirty_young_list(_young_list->first_region());
5648 }
5649 
5650 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5651                                                HeapWord* tams, HeapWord* end) {
5652   guarantee(tams <= end,
5653             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5654   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5655   if (result < end) {
5656     gclog_or_tty->cr();
5657     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5658                            bitmap_name, result);
5659     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5660                            bitmap_name, tams, end);
5661     return false;
5662   }
5663   return true;
5664 }
5665 
5666 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5667   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5668   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5669 
5670   HeapWord* bottom = hr->bottom();
5671   HeapWord* ptams  = hr->prev_top_at_mark_start();
5672   HeapWord* ntams  = hr->next_top_at_mark_start();
5673   HeapWord* end    = hr->end();
5674 
5675   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5676 
5677   bool res_n = true;
5678   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5679   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5680   // if we happen to be in that state.
5681   if (mark_in_progress() || !_cmThread->in_progress()) {
5682     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5683   }
5684   if (!res_p || !res_n) {
5685     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5686                            HR_FORMAT_PARAMS(hr));
5687     gclog_or_tty->print_cr("#### Caller: %s", caller);
5688     return false;
5689   }
5690   return true;
5691 }
5692 
5693 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5694   if (!G1VerifyBitmaps) return;
5695 
5696   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5697 }
5698 
5699 class G1VerifyBitmapClosure : public HeapRegionClosure {
5700 private:
5701   const char* _caller;
5702   G1CollectedHeap* _g1h;
5703   bool _failures;
5704 
5705 public:
5706   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5707     _caller(caller), _g1h(g1h), _failures(false) { }
5708 
5709   bool failures() { return _failures; }
5710 
5711   virtual bool doHeapRegion(HeapRegion* hr) {
5712     if (hr->is_continues_humongous()) return false;
5713 
5714     bool result = _g1h->verify_bitmaps(_caller, hr);
5715     if (!result) {
5716       _failures = true;
5717     }
5718     return false;
5719   }
5720 };
5721 
5722 void G1CollectedHeap::check_bitmaps(const char* caller) {
5723   if (!G1VerifyBitmaps) return;
5724 
5725   G1VerifyBitmapClosure cl(caller, this);
5726   heap_region_iterate(&cl);
5727   guarantee(!cl.failures(), "bitmap verification");
5728 }
5729 
5730 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5731  private:
5732   bool _failures;
5733  public:
5734   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5735 
5736   virtual bool doHeapRegion(HeapRegion* hr) {
5737     uint i = hr->hrm_index();
5738     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5739     if (hr->is_humongous()) {
5740       if (hr->in_collection_set()) {
5741         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5742         _failures = true;
5743         return true;
5744       }
5745       if (cset_state.is_in_cset()) {
5746         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5747         _failures = true;
5748         return true;
5749       }
5750       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5751         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5752         _failures = true;
5753         return true;
5754       }
5755     } else {
5756       if (cset_state.is_humongous()) {
5757         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5758         _failures = true;
5759         return true;
5760       }
5761       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5762         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5763                                hr->in_collection_set(), cset_state.value(), i);
5764         _failures = true;
5765         return true;
5766       }
5767       if (cset_state.is_in_cset()) {
5768         if (hr->is_young() != (cset_state.is_young())) {
5769           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5770                                  hr->is_young(), cset_state.value(), i);
5771           _failures = true;
5772           return true;
5773         }
5774         if (hr->is_old() != (cset_state.is_old())) {
5775           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5776                                  hr->is_old(), cset_state.value(), i);
5777           _failures = true;
5778           return true;
5779         }
5780       }
5781     }
5782     return false;
5783   }
5784 
5785   bool failures() const { return _failures; }
5786 };
5787 
5788 bool G1CollectedHeap::check_cset_fast_test() {
5789   G1CheckCSetFastTableClosure cl;
5790   _hrm.iterate(&cl);
5791   return !cl.failures();
5792 }
5793 #endif // PRODUCT
5794 
5795 void G1CollectedHeap::cleanUpCardTable() {
5796   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5797   double start = os::elapsedTime();
5798 
5799   {
5800     // Iterate over the dirty cards region list.
5801     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5802 
5803     set_par_threads();
5804     workers()->run_task(&cleanup_task);
5805     set_par_threads(0);
5806 #ifndef PRODUCT
5807     if (G1VerifyCTCleanup || VerifyAfterGC) {
5808       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5809       heap_region_iterate(&cleanup_verifier);
5810     }
5811 #endif
5812   }
5813 
5814   double elapsed = os::elapsedTime() - start;
5815   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5816 }
5817 
5818 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5819   size_t pre_used = 0;
5820   FreeRegionList local_free_list("Local List for CSet Freeing");
5821 
5822   double young_time_ms     = 0.0;
5823   double non_young_time_ms = 0.0;
5824 
5825   // Since the collection set is a superset of the the young list,
5826   // all we need to do to clear the young list is clear its
5827   // head and length, and unlink any young regions in the code below
5828   _young_list->clear();
5829 
5830   G1CollectorPolicy* policy = g1_policy();
5831 
5832   double start_sec = os::elapsedTime();
5833   bool non_young = true;
5834 
5835   HeapRegion* cur = cs_head;
5836   int age_bound = -1;
5837   size_t rs_lengths = 0;
5838 
5839   while (cur != NULL) {
5840     assert(!is_on_master_free_list(cur), "sanity");
5841     if (non_young) {
5842       if (cur->is_young()) {
5843         double end_sec = os::elapsedTime();
5844         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5845         non_young_time_ms += elapsed_ms;
5846 
5847         start_sec = os::elapsedTime();
5848         non_young = false;
5849       }
5850     } else {
5851       if (!cur->is_young()) {
5852         double end_sec = os::elapsedTime();
5853         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5854         young_time_ms += elapsed_ms;
5855 
5856         start_sec = os::elapsedTime();
5857         non_young = true;
5858       }
5859     }
5860 
5861     rs_lengths += cur->rem_set()->occupied_locked();
5862 
5863     HeapRegion* next = cur->next_in_collection_set();
5864     assert(cur->in_collection_set(), "bad CS");
5865     cur->set_next_in_collection_set(NULL);
5866     clear_in_cset(cur);
5867 
5868     if (cur->is_young()) {
5869       int index = cur->young_index_in_cset();
5870       assert(index != -1, "invariant");
5871       assert((uint) index < policy->young_cset_region_length(), "invariant");
5872       size_t words_survived = _surviving_young_words[index];
5873       cur->record_surv_words_in_group(words_survived);
5874 
5875       // At this point the we have 'popped' cur from the collection set
5876       // (linked via next_in_collection_set()) but it is still in the
5877       // young list (linked via next_young_region()). Clear the
5878       // _next_young_region field.
5879       cur->set_next_young_region(NULL);
5880     } else {
5881       int index = cur->young_index_in_cset();
5882       assert(index == -1, "invariant");
5883     }
5884 
5885     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5886             (!cur->is_young() && cur->young_index_in_cset() == -1),
5887             "invariant" );
5888 
5889     if (!cur->evacuation_failed()) {
5890       MemRegion used_mr = cur->used_region();
5891 
5892       // And the region is empty.
5893       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5894       pre_used += cur->used();
5895       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5896     } else {
5897       cur->uninstall_surv_rate_group();
5898       if (cur->is_young()) {
5899         cur->set_young_index_in_cset(-1);
5900       }
5901       cur->set_evacuation_failed(false);
5902       // The region is now considered to be old.
5903       cur->set_old();
5904       _old_set.add(cur);
5905       evacuation_info.increment_collectionset_used_after(cur->used());
5906     }
5907     cur = next;
5908   }
5909 
5910   evacuation_info.set_regions_freed(local_free_list.length());
5911   policy->record_max_rs_lengths(rs_lengths);
5912   policy->cset_regions_freed();
5913 
5914   double end_sec = os::elapsedTime();
5915   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5916 
5917   if (non_young) {
5918     non_young_time_ms += elapsed_ms;
5919   } else {
5920     young_time_ms += elapsed_ms;
5921   }
5922 
5923   prepend_to_freelist(&local_free_list);
5924   decrement_summary_bytes(pre_used);
5925   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5926   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5927 }
5928 
5929 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5930  private:
5931   FreeRegionList* _free_region_list;
5932   HeapRegionSet* _proxy_set;
5933   HeapRegionSetCount _humongous_regions_removed;
5934   size_t _freed_bytes;
5935  public:
5936 
5937   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5938     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5939   }
5940 
5941   virtual bool doHeapRegion(HeapRegion* r) {
5942     if (!r->is_starts_humongous()) {
5943       return false;
5944     }
5945 
5946     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5947 
5948     oop obj = (oop)r->bottom();
5949     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5950 
5951     // The following checks whether the humongous object is live are sufficient.
5952     // The main additional check (in addition to having a reference from the roots
5953     // or the young gen) is whether the humongous object has a remembered set entry.
5954     //
5955     // A humongous object cannot be live if there is no remembered set for it
5956     // because:
5957     // - there can be no references from within humongous starts regions referencing
5958     // the object because we never allocate other objects into them.
5959     // (I.e. there are no intra-region references that may be missed by the
5960     // remembered set)
5961     // - as soon there is a remembered set entry to the humongous starts region
5962     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5963     // until the end of a concurrent mark.
5964     //
5965     // It is not required to check whether the object has been found dead by marking
5966     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5967     // all objects allocated during that time are considered live.
5968     // SATB marking is even more conservative than the remembered set.
5969     // So if at this point in the collection there is no remembered set entry,
5970     // nobody has a reference to it.
5971     // At the start of collection we flush all refinement logs, and remembered sets
5972     // are completely up-to-date wrt to references to the humongous object.
5973     //
5974     // Other implementation considerations:
5975     // - never consider object arrays at this time because they would pose
5976     // considerable effort for cleaning up the the remembered sets. This is
5977     // required because stale remembered sets might reference locations that
5978     // are currently allocated into.
5979     uint region_idx = r->hrm_index();
5980     if (g1h->humongous_is_live(region_idx) ||
5981         g1h->humongous_region_is_always_live(region_idx)) {
5982 
5983       if (G1TraceEagerReclaimHumongousObjects) {
5984         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",
5985                                region_idx,
5986                                obj->size()*HeapWordSize,
5987                                r->bottom(),
5988                                r->region_num(),
5989                                r->rem_set()->occupied(),
5990                                r->rem_set()->strong_code_roots_list_length(),
5991                                next_bitmap->isMarked(r->bottom()),
5992                                g1h->humongous_is_live(region_idx),
5993                                obj->is_objArray()
5994                               );
5995       }
5996 
5997       return false;
5998     }
5999 
6000     guarantee(!obj->is_objArray(),
6001               err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6002                       r->bottom()));
6003 
6004     if (G1TraceEagerReclaimHumongousObjects) {
6005       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",
6006                              region_idx,
6007                              obj->size()*HeapWordSize,
6008                              r->bottom(),
6009                              r->region_num(),
6010                              r->rem_set()->occupied(),
6011                              r->rem_set()->strong_code_roots_list_length(),
6012                              next_bitmap->isMarked(r->bottom()),
6013                              g1h->humongous_is_live(region_idx),
6014                              obj->is_objArray()
6015                             );
6016     }
6017     // Need to clear mark bit of the humongous object if already set.
6018     if (next_bitmap->isMarked(r->bottom())) {
6019       next_bitmap->clear(r->bottom());
6020     }
6021     _freed_bytes += r->used();
6022     r->set_containing_set(NULL);
6023     _humongous_regions_removed.increment(1u, r->capacity());
6024     g1h->free_humongous_region(r, _free_region_list, false);
6025 
6026     return false;
6027   }
6028 
6029   HeapRegionSetCount& humongous_free_count() {
6030     return _humongous_regions_removed;
6031   }
6032 
6033   size_t bytes_freed() const {
6034     return _freed_bytes;
6035   }
6036 
6037   size_t humongous_reclaimed() const {
6038     return _humongous_regions_removed.length();
6039   }
6040 };
6041 
6042 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6043   assert_at_safepoint(true);
6044 
6045   if (!G1EagerReclaimHumongousObjects ||
6046       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6047     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6048     return;
6049   }
6050 
6051   double start_time = os::elapsedTime();
6052 
6053   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6054 
6055   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6056   heap_region_iterate(&cl);
6057 
6058   HeapRegionSetCount empty_set;
6059   remove_from_old_sets(empty_set, cl.humongous_free_count());
6060 
6061   G1HRPrinter* hr_printer = _g1h->hr_printer();
6062   if (hr_printer->is_active()) {
6063     FreeRegionListIterator iter(&local_cleanup_list);
6064     while (iter.more_available()) {
6065       HeapRegion* hr = iter.get_next();
6066       hr_printer->cleanup(hr);
6067     }
6068   }
6069 
6070   prepend_to_freelist(&local_cleanup_list);
6071   decrement_summary_bytes(cl.bytes_freed());
6072 
6073   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6074                                                                     cl.humongous_reclaimed());
6075 }
6076 
6077 // This routine is similar to the above but does not record
6078 // any policy statistics or update free lists; we are abandoning
6079 // the current incremental collection set in preparation of a
6080 // full collection. After the full GC we will start to build up
6081 // the incremental collection set again.
6082 // This is only called when we're doing a full collection
6083 // and is immediately followed by the tearing down of the young list.
6084 
6085 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6086   HeapRegion* cur = cs_head;
6087 
6088   while (cur != NULL) {
6089     HeapRegion* next = cur->next_in_collection_set();
6090     assert(cur->in_collection_set(), "bad CS");
6091     cur->set_next_in_collection_set(NULL);
6092     clear_in_cset(cur);
6093     cur->set_young_index_in_cset(-1);
6094     cur = next;
6095   }
6096 }
6097 
6098 void G1CollectedHeap::set_free_regions_coming() {
6099   if (G1ConcRegionFreeingVerbose) {
6100     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6101                            "setting free regions coming");
6102   }
6103 
6104   assert(!free_regions_coming(), "pre-condition");
6105   _free_regions_coming = true;
6106 }
6107 
6108 void G1CollectedHeap::reset_free_regions_coming() {
6109   assert(free_regions_coming(), "pre-condition");
6110 
6111   {
6112     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6113     _free_regions_coming = false;
6114     SecondaryFreeList_lock->notify_all();
6115   }
6116 
6117   if (G1ConcRegionFreeingVerbose) {
6118     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6119                            "reset free regions coming");
6120   }
6121 }
6122 
6123 void G1CollectedHeap::wait_while_free_regions_coming() {
6124   // Most of the time we won't have to wait, so let's do a quick test
6125   // first before we take the lock.
6126   if (!free_regions_coming()) {
6127     return;
6128   }
6129 
6130   if (G1ConcRegionFreeingVerbose) {
6131     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6132                            "waiting for free regions");
6133   }
6134 
6135   {
6136     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6137     while (free_regions_coming()) {
6138       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6139     }
6140   }
6141 
6142   if (G1ConcRegionFreeingVerbose) {
6143     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6144                            "done waiting for free regions");
6145   }
6146 }
6147 
6148 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6149   _young_list->push_region(hr);
6150 }
6151 
6152 class NoYoungRegionsClosure: public HeapRegionClosure {
6153 private:
6154   bool _success;
6155 public:
6156   NoYoungRegionsClosure() : _success(true) { }
6157   bool doHeapRegion(HeapRegion* r) {
6158     if (r->is_young()) {
6159       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6160                              r->bottom(), r->end());
6161       _success = false;
6162     }
6163     return false;
6164   }
6165   bool success() { return _success; }
6166 };
6167 
6168 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6169   bool ret = _young_list->check_list_empty(check_sample);
6170 
6171   if (check_heap) {
6172     NoYoungRegionsClosure closure;
6173     heap_region_iterate(&closure);
6174     ret = ret && closure.success();
6175   }
6176 
6177   return ret;
6178 }
6179 
6180 class TearDownRegionSetsClosure : public HeapRegionClosure {
6181 private:
6182   HeapRegionSet *_old_set;
6183 
6184 public:
6185   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6186 
6187   bool doHeapRegion(HeapRegion* r) {
6188     if (r->is_old()) {
6189       _old_set->remove(r);
6190     } else {
6191       // We ignore free regions, we'll empty the free list afterwards.
6192       // We ignore young regions, we'll empty the young list afterwards.
6193       // We ignore humongous regions, we're not tearing down the
6194       // humongous regions set.
6195       assert(r->is_free() || r->is_young() || r->is_humongous(),
6196              "it cannot be another type");
6197     }
6198     return false;
6199   }
6200 
6201   ~TearDownRegionSetsClosure() {
6202     assert(_old_set->is_empty(), "post-condition");
6203   }
6204 };
6205 
6206 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6207   assert_at_safepoint(true /* should_be_vm_thread */);
6208 
6209   if (!free_list_only) {
6210     TearDownRegionSetsClosure cl(&_old_set);
6211     heap_region_iterate(&cl);
6212 
6213     // Note that emptying the _young_list is postponed and instead done as
6214     // the first step when rebuilding the regions sets again. The reason for
6215     // this is that during a full GC string deduplication needs to know if
6216     // a collected region was young or old when the full GC was initiated.
6217   }
6218   _hrm.remove_all_free_regions();
6219 }
6220 
6221 class RebuildRegionSetsClosure : public HeapRegionClosure {
6222 private:
6223   bool            _free_list_only;
6224   HeapRegionSet*   _old_set;
6225   HeapRegionManager*   _hrm;
6226   size_t          _total_used;
6227 
6228 public:
6229   RebuildRegionSetsClosure(bool free_list_only,
6230                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6231     _free_list_only(free_list_only),
6232     _old_set(old_set), _hrm(hrm), _total_used(0) {
6233     assert(_hrm->num_free_regions() == 0, "pre-condition");
6234     if (!free_list_only) {
6235       assert(_old_set->is_empty(), "pre-condition");
6236     }
6237   }
6238 
6239   bool doHeapRegion(HeapRegion* r) {
6240     if (r->is_continues_humongous()) {
6241       return false;
6242     }
6243 
6244     if (r->is_empty()) {
6245       // Add free regions to the free list
6246       r->set_free();
6247       r->set_allocation_context(AllocationContext::system());
6248       _hrm->insert_into_free_list(r);
6249     } else if (!_free_list_only) {
6250       assert(!r->is_young(), "we should not come across young regions");
6251 
6252       if (r->is_humongous()) {
6253         // We ignore humongous regions, we left the humongous set unchanged
6254       } else {
6255         // Objects that were compacted would have ended up on regions
6256         // that were previously old or free.
6257         assert(r->is_free() || r->is_old(), "invariant");
6258         // We now consider them old, so register as such.
6259         r->set_old();
6260         _old_set->add(r);
6261       }
6262       _total_used += r->used();
6263     }
6264 
6265     return false;
6266   }
6267 
6268   size_t total_used() {
6269     return _total_used;
6270   }
6271 };
6272 
6273 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6274   assert_at_safepoint(true /* should_be_vm_thread */);
6275 
6276   if (!free_list_only) {
6277     _young_list->empty_list();
6278   }
6279 
6280   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6281   heap_region_iterate(&cl);
6282 
6283   if (!free_list_only) {
6284     _allocator->set_used(cl.total_used());
6285   }
6286   assert(_allocator->used_unlocked() == recalculate_used(),
6287          err_msg("inconsistent _allocator->used_unlocked(), "
6288                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6289                  _allocator->used_unlocked(), recalculate_used()));
6290 }
6291 
6292 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6293   _refine_cte_cl->set_concurrent(concurrent);
6294 }
6295 
6296 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6297   HeapRegion* hr = heap_region_containing(p);
6298   return hr->is_in(p);
6299 }
6300 
6301 // Methods for the mutator alloc region
6302 
6303 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6304                                                       bool force) {
6305   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6306   assert(!force || g1_policy()->can_expand_young_list(),
6307          "if force is true we should be able to expand the young list");
6308   bool young_list_full = g1_policy()->is_young_list_full();
6309   if (force || !young_list_full) {
6310     HeapRegion* new_alloc_region = new_region(word_size,
6311                                               false /* is_old */,
6312                                               false /* do_expand */);
6313     if (new_alloc_region != NULL) {
6314       set_region_short_lived_locked(new_alloc_region);
6315       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6316       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6317       return new_alloc_region;
6318     }
6319   }
6320   return NULL;
6321 }
6322 
6323 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6324                                                   size_t allocated_bytes) {
6325   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6326   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6327 
6328   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6329   _allocator->increase_used(allocated_bytes);
6330   _hr_printer.retire(alloc_region);
6331   // We update the eden sizes here, when the region is retired,
6332   // instead of when it's allocated, since this is the point that its
6333   // used space has been recored in _summary_bytes_used.
6334   g1mm()->update_eden_size();
6335 }
6336 
6337 void G1CollectedHeap::set_par_threads() {
6338   // Don't change the number of workers.  Use the value previously set
6339   // in the workgroup.
6340   uint n_workers = workers()->active_workers();
6341   assert(UseDynamicNumberOfGCThreads ||
6342            n_workers == workers()->total_workers(),
6343       "Otherwise should be using the total number of workers");
6344   if (n_workers == 0) {
6345     assert(false, "Should have been set in prior evacuation pause.");
6346     n_workers = ParallelGCThreads;
6347     workers()->set_active_workers(n_workers);
6348   }
6349   set_par_threads(n_workers);
6350 }
6351 
6352 // Methods for the GC alloc regions
6353 
6354 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6355                                                  uint count,
6356                                                  InCSetState dest) {
6357   assert(FreeList_lock->owned_by_self(), "pre-condition");
6358 
6359   if (count < g1_policy()->max_regions(dest)) {
6360     const bool is_survivor = (dest.is_young());
6361     HeapRegion* new_alloc_region = new_region(word_size,
6362                                               !is_survivor,
6363                                               true /* do_expand */);
6364     if (new_alloc_region != NULL) {
6365       // We really only need to do this for old regions given that we
6366       // should never scan survivors. But it doesn't hurt to do it
6367       // for survivors too.
6368       new_alloc_region->record_timestamp();
6369       if (is_survivor) {
6370         new_alloc_region->set_survivor();
6371         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6372         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6373       } else {
6374         new_alloc_region->set_old();
6375         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6376         check_bitmaps("Old Region Allocation", new_alloc_region);
6377       }
6378       bool during_im = g1_policy()->during_initial_mark_pause();
6379       new_alloc_region->note_start_of_copying(during_im);
6380       return new_alloc_region;
6381     }
6382   }
6383   return NULL;
6384 }
6385 
6386 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6387                                              size_t allocated_bytes,
6388                                              InCSetState dest) {
6389   bool during_im = g1_policy()->during_initial_mark_pause();
6390   alloc_region->note_end_of_copying(during_im);
6391   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6392   if (dest.is_young()) {
6393     young_list()->add_survivor_region(alloc_region);
6394   } else {
6395     _old_set.add(alloc_region);
6396   }
6397   _hr_printer.retire(alloc_region);
6398 }
6399 
6400 // Heap region set verification
6401 
6402 class VerifyRegionListsClosure : public HeapRegionClosure {
6403 private:
6404   HeapRegionSet*   _old_set;
6405   HeapRegionSet*   _humongous_set;
6406   HeapRegionManager*   _hrm;
6407 
6408 public:
6409   HeapRegionSetCount _old_count;
6410   HeapRegionSetCount _humongous_count;
6411   HeapRegionSetCount _free_count;
6412 
6413   VerifyRegionListsClosure(HeapRegionSet* old_set,
6414                            HeapRegionSet* humongous_set,
6415                            HeapRegionManager* hrm) :
6416     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6417     _old_count(), _humongous_count(), _free_count(){ }
6418 
6419   bool doHeapRegion(HeapRegion* hr) {
6420     if (hr->is_continues_humongous()) {
6421       return false;
6422     }
6423 
6424     if (hr->is_young()) {
6425       // TODO
6426     } else if (hr->is_starts_humongous()) {
6427       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6428       _humongous_count.increment(1u, hr->capacity());
6429     } else if (hr->is_empty()) {
6430       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6431       _free_count.increment(1u, hr->capacity());
6432     } else if (hr->is_old()) {
6433       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6434       _old_count.increment(1u, hr->capacity());
6435     } else {
6436       ShouldNotReachHere();
6437     }
6438     return false;
6439   }
6440 
6441   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6442     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6443     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6444         old_set->total_capacity_bytes(), _old_count.capacity()));
6445 
6446     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6447     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6448         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6449 
6450     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()));
6451     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6452         free_list->total_capacity_bytes(), _free_count.capacity()));
6453   }
6454 };
6455 
6456 void G1CollectedHeap::verify_region_sets() {
6457   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6458 
6459   // First, check the explicit lists.
6460   _hrm.verify();
6461   {
6462     // Given that a concurrent operation might be adding regions to
6463     // the secondary free list we have to take the lock before
6464     // verifying it.
6465     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6466     _secondary_free_list.verify_list();
6467   }
6468 
6469   // If a concurrent region freeing operation is in progress it will
6470   // be difficult to correctly attributed any free regions we come
6471   // across to the correct free list given that they might belong to
6472   // one of several (free_list, secondary_free_list, any local lists,
6473   // etc.). So, if that's the case we will skip the rest of the
6474   // verification operation. Alternatively, waiting for the concurrent
6475   // operation to complete will have a non-trivial effect on the GC's
6476   // operation (no concurrent operation will last longer than the
6477   // interval between two calls to verification) and it might hide
6478   // any issues that we would like to catch during testing.
6479   if (free_regions_coming()) {
6480     return;
6481   }
6482 
6483   // Make sure we append the secondary_free_list on the free_list so
6484   // that all free regions we will come across can be safely
6485   // attributed to the free_list.
6486   append_secondary_free_list_if_not_empty_with_lock();
6487 
6488   // Finally, make sure that the region accounting in the lists is
6489   // consistent with what we see in the heap.
6490 
6491   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6492   heap_region_iterate(&cl);
6493   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6494 }
6495 
6496 // Optimized nmethod scanning
6497 
6498 class RegisterNMethodOopClosure: public OopClosure {
6499   G1CollectedHeap* _g1h;
6500   nmethod* _nm;
6501 
6502   template <class T> void do_oop_work(T* p) {
6503     T heap_oop = oopDesc::load_heap_oop(p);
6504     if (!oopDesc::is_null(heap_oop)) {
6505       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6506       HeapRegion* hr = _g1h->heap_region_containing(obj);
6507       assert(!hr->is_continues_humongous(),
6508              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6509                      " starting at "HR_FORMAT,
6510                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6511 
6512       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6513       hr->add_strong_code_root_locked(_nm);
6514     }
6515   }
6516 
6517 public:
6518   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6519     _g1h(g1h), _nm(nm) {}
6520 
6521   void do_oop(oop* p)       { do_oop_work(p); }
6522   void do_oop(narrowOop* p) { do_oop_work(p); }
6523 };
6524 
6525 class UnregisterNMethodOopClosure: public OopClosure {
6526   G1CollectedHeap* _g1h;
6527   nmethod* _nm;
6528 
6529   template <class T> void do_oop_work(T* p) {
6530     T heap_oop = oopDesc::load_heap_oop(p);
6531     if (!oopDesc::is_null(heap_oop)) {
6532       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6533       HeapRegion* hr = _g1h->heap_region_containing(obj);
6534       assert(!hr->is_continues_humongous(),
6535              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6536                      " starting at "HR_FORMAT,
6537                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6538 
6539       hr->remove_strong_code_root(_nm);
6540     }
6541   }
6542 
6543 public:
6544   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6545     _g1h(g1h), _nm(nm) {}
6546 
6547   void do_oop(oop* p)       { do_oop_work(p); }
6548   void do_oop(narrowOop* p) { do_oop_work(p); }
6549 };
6550 
6551 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6552   CollectedHeap::register_nmethod(nm);
6553 
6554   guarantee(nm != NULL, "sanity");
6555   RegisterNMethodOopClosure reg_cl(this, nm);
6556   nm->oops_do(&reg_cl);
6557 }
6558 
6559 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6560   CollectedHeap::unregister_nmethod(nm);
6561 
6562   guarantee(nm != NULL, "sanity");
6563   UnregisterNMethodOopClosure reg_cl(this, nm);
6564   nm->oops_do(&reg_cl, true);
6565 }
6566 
6567 void G1CollectedHeap::purge_code_root_memory() {
6568   double purge_start = os::elapsedTime();
6569   G1CodeRootSet::purge();
6570   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6571   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6572 }
6573 
6574 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6575   G1CollectedHeap* _g1h;
6576 
6577 public:
6578   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6579     _g1h(g1h) {}
6580 
6581   void do_code_blob(CodeBlob* cb) {
6582     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6583     if (nm == NULL) {
6584       return;
6585     }
6586 
6587     if (ScavengeRootsInCode) {
6588       _g1h->register_nmethod(nm);
6589     }
6590   }
6591 };
6592 
6593 void G1CollectedHeap::rebuild_strong_code_roots() {
6594   RebuildStrongCodeRootClosure blob_cl(this);
6595   CodeCache::blobs_do(&blob_cl);
6596 }