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 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "code/icBuffer.hpp"
  30 #include "gc/g1/bufferingOopClosure.hpp"
  31 #include "gc/g1/concurrentG1Refine.hpp"
  32 #include "gc/g1/concurrentG1RefineThread.hpp"
  33 #include "gc/g1/concurrentMarkThread.inline.hpp"
  34 #include "gc/g1/g1Allocator.inline.hpp"
  35 #include "gc/g1/g1CollectedHeap.inline.hpp"
  36 #include "gc/g1/g1CollectorPolicy.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ErgoVerbose.hpp"
  39 #include "gc/g1/g1EvacFailure.hpp"
  40 #include "gc/g1/g1GCPhaseTimes.hpp"
  41 #include "gc/g1/g1Log.hpp"
  42 #include "gc/g1/g1MarkSweep.hpp"
  43 #include "gc/g1/g1OopClosures.inline.hpp"
  44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  46 #include "gc/g1/g1RemSet.inline.hpp"
  47 #include "gc/g1/g1RootProcessor.hpp"
  48 #include "gc/g1/g1StringDedup.hpp"
  49 #include "gc/g1/g1YCTypes.hpp"
  50 #include "gc/g1/heapRegion.inline.hpp"
  51 #include "gc/g1/heapRegionRemSet.hpp"
  52 #include "gc/g1/heapRegionSet.inline.hpp"
  53 #include "gc/g1/suspendibleThreadSet.hpp"
  54 #include "gc/g1/vm_operations_g1.hpp"
  55 #include "gc/shared/gcHeapSummary.hpp"
  56 #include "gc/shared/gcLocker.inline.hpp"
  57 #include "gc/shared/gcTimer.hpp"
  58 #include "gc/shared/gcTrace.hpp"
  59 #include "gc/shared/gcTraceTime.hpp"
  60 #include "gc/shared/generationSpec.hpp"
  61 #include "gc/shared/isGCActiveMark.hpp"
  62 #include "gc/shared/referenceProcessor.hpp"
  63 #include "gc/shared/taskqueue.inline.hpp"
  64 #include "memory/allocation.hpp"
  65 #include "memory/iterator.hpp"
  66 #include "oops/oop.inline.hpp"
  67 #include "runtime/atomic.inline.hpp"
  68 #include "runtime/init.hpp"
  69 #include "runtime/orderAccess.inline.hpp"
  70 #include "runtime/vmThread.hpp"
  71 #include "utilities/globalDefinitions.hpp"
  72 #include "utilities/stack.inline.hpp"
  73 
  74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  75 
  76 // turn it on so that the contents of the young list (scan-only /
  77 // to-be-collected) are printed at "strategic" points before / during
  78 // / after the collection --- this is useful for debugging
  79 #define YOUNG_LIST_VERBOSE 0
  80 // CURRENT STATUS
  81 // This file is under construction.  Search for "FIXME".
  82 
  83 // INVARIANTS/NOTES
  84 //
  85 // All allocation activity covered by the G1CollectedHeap interface is
  86 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  87 // and allocate_new_tlab, which are the "entry" points to the
  88 // allocation code from the rest of the JVM.  (Note that this does not
  89 // apply to TLAB allocation, which is not part of this interface: it
  90 // is done by clients of this interface.)
  91 
  92 // Local to this file.
  93 
  94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  95   bool _concurrent;
  96 public:
  97   RefineCardTableEntryClosure() : _concurrent(true) { }
  98 
  99   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 100     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 101     // This path is executed by the concurrent refine or mutator threads,
 102     // concurrently, and so we do not care if card_ptr contains references
 103     // that point into the collection set.
 104     assert(!oops_into_cset, "should be");
 105 
 106     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 107       // Caller will actually yield.
 108       return false;
 109     }
 110     // Otherwise, we finished successfully; return true.
 111     return true;
 112   }
 113 
 114   void set_concurrent(bool b) { _concurrent = b; }
 115 };
 116 
 117 
 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 119  private:
 120   size_t _num_processed;
 121 
 122  public:
 123   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 124 
 125   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 126     *card_ptr = CardTableModRefBS::dirty_card_val();
 127     _num_processed++;
 128     return true;
 129   }
 130 
 131   size_t num_processed() const { return _num_processed; }
 132 };
 133 
 134 YoungList::YoungList(G1CollectedHeap* g1h) :
 135     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 136     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 137   guarantee(check_list_empty(false), "just making sure...");
 138 }
 139 
 140 void YoungList::push_region(HeapRegion *hr) {
 141   assert(!hr->is_young(), "should not already be young");
 142   assert(hr->get_next_young_region() == NULL, "cause it should!");
 143 
 144   hr->set_next_young_region(_head);
 145   _head = hr;
 146 
 147   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 148   ++_length;
 149 }
 150 
 151 void YoungList::add_survivor_region(HeapRegion* hr) {
 152   assert(hr->is_survivor(), "should be flagged as survivor region");
 153   assert(hr->get_next_young_region() == NULL, "cause it should!");
 154 
 155   hr->set_next_young_region(_survivor_head);
 156   if (_survivor_head == NULL) {
 157     _survivor_tail = hr;
 158   }
 159   _survivor_head = hr;
 160   ++_survivor_length;
 161 }
 162 
 163 void YoungList::empty_list(HeapRegion* list) {
 164   while (list != NULL) {
 165     HeapRegion* next = list->get_next_young_region();
 166     list->set_next_young_region(NULL);
 167     list->uninstall_surv_rate_group();
 168     // This is called before a Full GC and all the non-empty /
 169     // non-humongous regions at the end of the Full GC will end up as
 170     // old anyway.
 171     list->set_old();
 172     list = next;
 173   }
 174 }
 175 
 176 void YoungList::empty_list() {
 177   assert(check_list_well_formed(), "young list should be well formed");
 178 
 179   empty_list(_head);
 180   _head = NULL;
 181   _length = 0;
 182 
 183   empty_list(_survivor_head);
 184   _survivor_head = NULL;
 185   _survivor_tail = NULL;
 186   _survivor_length = 0;
 187 
 188   _last_sampled_rs_lengths = 0;
 189 
 190   assert(check_list_empty(false), "just making sure...");
 191 }
 192 
 193 bool YoungList::check_list_well_formed() {
 194   bool ret = true;
 195 
 196   uint length = 0;
 197   HeapRegion* curr = _head;
 198   HeapRegion* last = NULL;
 199   while (curr != NULL) {
 200     if (!curr->is_young()) {
 201       gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
 202                              "incorrectly tagged (y: %d, surv: %d)",
 203                              p2i(curr->bottom()), p2i(curr->end()),
 204                              curr->is_young(), curr->is_survivor());
 205       ret = false;
 206     }
 207     ++length;
 208     last = curr;
 209     curr = curr->get_next_young_region();
 210   }
 211   ret = ret && (length == _length);
 212 
 213   if (!ret) {
 214     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 215     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 216                            length, _length);
 217   }
 218 
 219   return ret;
 220 }
 221 
 222 bool YoungList::check_list_empty(bool check_sample) {
 223   bool ret = true;
 224 
 225   if (_length != 0) {
 226     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 227                   _length);
 228     ret = false;
 229   }
 230   if (check_sample && _last_sampled_rs_lengths != 0) {
 231     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 232     ret = false;
 233   }
 234   if (_head != NULL) {
 235     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 236     ret = false;
 237   }
 238   if (!ret) {
 239     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 240   }
 241 
 242   return ret;
 243 }
 244 
 245 void
 246 YoungList::rs_length_sampling_init() {
 247   _sampled_rs_lengths = 0;
 248   _curr               = _head;
 249 }
 250 
 251 bool
 252 YoungList::rs_length_sampling_more() {
 253   return _curr != NULL;
 254 }
 255 
 256 void
 257 YoungList::rs_length_sampling_next() {
 258   assert( _curr != NULL, "invariant" );
 259   size_t rs_length = _curr->rem_set()->occupied();
 260 
 261   _sampled_rs_lengths += rs_length;
 262 
 263   // The current region may not yet have been added to the
 264   // incremental collection set (it gets added when it is
 265   // retired as the current allocation region).
 266   if (_curr->in_collection_set()) {
 267     // Update the collection set policy information for this region
 268     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 269   }
 270 
 271   _curr = _curr->get_next_young_region();
 272   if (_curr == NULL) {
 273     _last_sampled_rs_lengths = _sampled_rs_lengths;
 274     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 275   }
 276 }
 277 
 278 void
 279 YoungList::reset_auxilary_lists() {
 280   guarantee( is_empty(), "young list should be empty" );
 281   assert(check_list_well_formed(), "young list should be well formed");
 282 
 283   // Add survivor regions to SurvRateGroup.
 284   _g1h->g1_policy()->note_start_adding_survivor_regions();
 285   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 286 
 287   int young_index_in_cset = 0;
 288   for (HeapRegion* curr = _survivor_head;
 289        curr != NULL;
 290        curr = curr->get_next_young_region()) {
 291     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 292 
 293     // The region is a non-empty survivor so let's add it to
 294     // the incremental collection set for the next evacuation
 295     // pause.
 296     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 297     young_index_in_cset += 1;
 298   }
 299   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 300   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 301 
 302   _head   = _survivor_head;
 303   _length = _survivor_length;
 304   if (_survivor_head != NULL) {
 305     assert(_survivor_tail != NULL, "cause it shouldn't be");
 306     assert(_survivor_length > 0, "invariant");
 307     _survivor_tail->set_next_young_region(NULL);
 308   }
 309 
 310   // Don't clear the survivor list handles until the start of
 311   // the next evacuation pause - we need it in order to re-tag
 312   // the survivor regions from this evacuation pause as 'young'
 313   // at the start of the next.
 314 
 315   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 316 
 317   assert(check_list_well_formed(), "young list should be well formed");
 318 }
 319 
 320 void YoungList::print() {
 321   HeapRegion* lists[] = {_head,   _survivor_head};
 322   const char* names[] = {"YOUNG", "SURVIVOR"};
 323 
 324   for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
 325     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 326     HeapRegion *curr = lists[list];
 327     if (curr == NULL)
 328       gclog_or_tty->print_cr("  empty");
 329     while (curr != NULL) {
 330       gclog_or_tty->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
 331                              HR_FORMAT_PARAMS(curr),
 332                              p2i(curr->prev_top_at_mark_start()),
 333                              p2i(curr->next_top_at_mark_start()),
 334                              curr->age_in_surv_rate_group_cond());
 335       curr = curr->get_next_young_region();
 336     }
 337   }
 338 
 339   gclog_or_tty->cr();
 340 }
 341 
 342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 343   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 344 }
 345 
 346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 347   // The from card cache is not the memory that is actually committed. So we cannot
 348   // take advantage of the zero_filled parameter.
 349   reset_from_card_cache(start_idx, num_regions);
 350 }
 351 
 352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 353 {
 354   // Claim the right to put the region on the dirty cards region list
 355   // by installing a self pointer.
 356   HeapRegion* next = hr->get_next_dirty_cards_region();
 357   if (next == NULL) {
 358     HeapRegion* res = (HeapRegion*)
 359       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 360                           NULL);
 361     if (res == NULL) {
 362       HeapRegion* head;
 363       do {
 364         // Put the region to the dirty cards region list.
 365         head = _dirty_cards_region_list;
 366         next = (HeapRegion*)
 367           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 368         if (next == head) {
 369           assert(hr->get_next_dirty_cards_region() == hr,
 370                  "hr->get_next_dirty_cards_region() != hr");
 371           if (next == NULL) {
 372             // The last region in the list points to itself.
 373             hr->set_next_dirty_cards_region(hr);
 374           } else {
 375             hr->set_next_dirty_cards_region(next);
 376           }
 377         }
 378       } while (next != head);
 379     }
 380   }
 381 }
 382 
 383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 384 {
 385   HeapRegion* head;
 386   HeapRegion* hr;
 387   do {
 388     head = _dirty_cards_region_list;
 389     if (head == NULL) {
 390       return NULL;
 391     }
 392     HeapRegion* new_head = head->get_next_dirty_cards_region();
 393     if (head == new_head) {
 394       // The last region.
 395       new_head = NULL;
 396     }
 397     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 398                                           head);
 399   } while (hr != head);
 400   assert(hr != NULL, "invariant");
 401   hr->set_next_dirty_cards_region(NULL);
 402   return hr;
 403 }
 404 
 405 // Returns true if the reference points to an object that
 406 // can move in an incremental collection.
 407 bool G1CollectedHeap::is_scavengable(const void* p) {
 408   HeapRegion* hr = heap_region_containing(p);
 409   return !hr->is_pinned();
 410 }
 411 
 412 // Private methods.
 413 
 414 HeapRegion*
 415 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 416   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 417   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 418     if (!_secondary_free_list.is_empty()) {
 419       if (G1ConcRegionFreeingVerbose) {
 420         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 421                                "secondary_free_list has %u entries",
 422                                _secondary_free_list.length());
 423       }
 424       // It looks as if there are free regions available on the
 425       // secondary_free_list. Let's move them to the free_list and try
 426       // again to allocate from it.
 427       append_secondary_free_list();
 428 
 429       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 430              "empty we should have moved at least one entry to the free_list");
 431       HeapRegion* res = _hrm.allocate_free_region(is_old);
 432       if (G1ConcRegionFreeingVerbose) {
 433         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 434                                "allocated " HR_FORMAT " from secondary_free_list",
 435                                HR_FORMAT_PARAMS(res));
 436       }
 437       return res;
 438     }
 439 
 440     // Wait here until we get notified either when (a) there are no
 441     // more free regions coming or (b) some regions have been moved on
 442     // the secondary_free_list.
 443     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 444   }
 445 
 446   if (G1ConcRegionFreeingVerbose) {
 447     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 448                            "could not allocate from secondary_free_list");
 449   }
 450   return NULL;
 451 }
 452 
 453 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 454   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 455          "the only time we use this to allocate a humongous region is "
 456          "when we are allocating a single humongous region");
 457 
 458   HeapRegion* res;
 459   if (G1StressConcRegionFreeing) {
 460     if (!_secondary_free_list.is_empty()) {
 461       if (G1ConcRegionFreeingVerbose) {
 462         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 463                                "forced to look at the secondary_free_list");
 464       }
 465       res = new_region_try_secondary_free_list(is_old);
 466       if (res != NULL) {
 467         return res;
 468       }
 469     }
 470   }
 471 
 472   res = _hrm.allocate_free_region(is_old);
 473 
 474   if (res == NULL) {
 475     if (G1ConcRegionFreeingVerbose) {
 476       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 477                              "res == NULL, trying the secondary_free_list");
 478     }
 479     res = new_region_try_secondary_free_list(is_old);
 480   }
 481   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 482     // Currently, only attempts to allocate GC alloc regions set
 483     // do_expand to true. So, we should only reach here during a
 484     // safepoint. If this assumption changes we might have to
 485     // reconsider the use of _expand_heap_after_alloc_failure.
 486     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 487 
 488     ergo_verbose1(ErgoHeapSizing,
 489                   "attempt heap expansion",
 490                   ergo_format_reason("region allocation request failed")
 491                   ergo_format_byte("allocation request"),
 492                   word_size * HeapWordSize);
 493     if (expand(word_size * HeapWordSize)) {
 494       // Given that expand() succeeded in expanding the heap, and we
 495       // always expand the heap by an amount aligned to the heap
 496       // region size, the free list should in theory not be empty.
 497       // In either case allocate_free_region() will check for NULL.
 498       res = _hrm.allocate_free_region(is_old);
 499     } else {
 500       _expand_heap_after_alloc_failure = false;
 501     }
 502   }
 503   return res;
 504 }
 505 
 506 HeapWord*
 507 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 508                                                            uint num_regions,
 509                                                            size_t word_size,
 510                                                            AllocationContext_t context) {
 511   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 512   assert(is_humongous(word_size), "word_size should be humongous");
 513   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 514 
 515   // Index of last region in the series + 1.
 516   uint last = first + num_regions;
 517 
 518   // We need to initialize the region(s) we just discovered. This is
 519   // a bit tricky given that it can happen concurrently with
 520   // refinement threads refining cards on these regions and
 521   // potentially wanting to refine the BOT as they are scanning
 522   // those cards (this can happen shortly after a cleanup; see CR
 523   // 6991377). So we have to set up the region(s) carefully and in
 524   // a specific order.
 525 
 526   // The word size sum of all the regions we will allocate.
 527   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 528   assert(word_size <= word_size_sum, "sanity");
 529 
 530   // This will be the "starts humongous" region.
 531   HeapRegion* first_hr = region_at(first);
 532   // The header of the new object will be placed at the bottom of
 533   // the first region.
 534   HeapWord* new_obj = first_hr->bottom();
 535   // This will be the new end of the first region in the series that
 536   // should also match the end of the last region in the series.
 537   HeapWord* new_end = new_obj + word_size_sum;
 538   // This will be the new top of the first region that will reflect
 539   // this allocation.
 540   HeapWord* new_top = new_obj + word_size;
 541 
 542   // First, we need to zero the header of the space that we will be
 543   // allocating. When we update top further down, some refinement
 544   // threads might try to scan the region. By zeroing the header we
 545   // ensure that any thread that will try to scan the region will
 546   // come across the zero klass word and bail out.
 547   //
 548   // NOTE: It would not have been correct to have used
 549   // CollectedHeap::fill_with_object() and make the space look like
 550   // an int array. The thread that is doing the allocation will
 551   // later update the object header to a potentially different array
 552   // type and, for a very short period of time, the klass and length
 553   // fields will be inconsistent. This could cause a refinement
 554   // thread to calculate the object size incorrectly.
 555   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 556 
 557   // We will set up the first region as "starts humongous". This
 558   // will also update the BOT covering all the regions to reflect
 559   // that there is a single object that starts at the bottom of the
 560   // first region.
 561   first_hr->set_starts_humongous(new_top, new_end);
 562   first_hr->set_allocation_context(context);
 563   // Then, if there are any, we will set up the "continues
 564   // humongous" regions.
 565   HeapRegion* hr = NULL;
 566   for (uint i = first + 1; i < last; ++i) {
 567     hr = region_at(i);
 568     hr->set_continues_humongous(first_hr);
 569     hr->set_allocation_context(context);
 570   }
 571   // If we have "continues humongous" regions (hr != NULL), then the
 572   // end of the last one should match new_end.
 573   assert(hr == NULL || hr->end() == new_end, "sanity");
 574 
 575   // Up to this point no concurrent thread would have been able to
 576   // do any scanning on any region in this series. All the top
 577   // fields still point to bottom, so the intersection between
 578   // [bottom,top] and [card_start,card_end] will be empty. Before we
 579   // update the top fields, we'll do a storestore to make sure that
 580   // no thread sees the update to top before the zeroing of the
 581   // object header and the BOT initialization.
 582   OrderAccess::storestore();
 583 
 584   // Now that the BOT and the object header have been initialized,
 585   // we can update top of the "starts humongous" region.
 586   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 587          "new_top should be in this region");
 588   first_hr->set_top(new_top);
 589   if (_hr_printer.is_active()) {
 590     HeapWord* bottom = first_hr->bottom();
 591     HeapWord* end = first_hr->orig_end();
 592     if ((first + 1) == last) {
 593       // the series has a single humongous region
 594       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 595     } else {
 596       // the series has more than one humongous regions
 597       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 598     }
 599   }
 600 
 601   // Now, we will update the top fields of the "continues humongous"
 602   // regions. The reason we need to do this is that, otherwise,
 603   // these regions would look empty and this will confuse parts of
 604   // G1. For example, the code that looks for a consecutive number
 605   // of empty regions will consider them empty and try to
 606   // re-allocate them. We can extend is_empty() to also include
 607   // !is_continues_humongous(), but it is easier to just update the top
 608   // fields here. The way we set top for all regions (i.e., top ==
 609   // end for all regions but the last one, top == new_top for the
 610   // last one) is actually used when we will free up the humongous
 611   // region in free_humongous_region().
 612   hr = NULL;
 613   for (uint i = first + 1; i < last; ++i) {
 614     hr = region_at(i);
 615     if ((i + 1) == last) {
 616       // last continues humongous region
 617       assert(hr->bottom() < new_top && new_top <= hr->end(),
 618              "new_top should fall on this region");
 619       hr->set_top(new_top);
 620       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 621     } else {
 622       // not last one
 623       assert(new_top > hr->end(), "new_top should be above this region");
 624       hr->set_top(hr->end());
 625       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 626     }
 627   }
 628   // If we have continues humongous regions (hr != NULL), then the
 629   // end of the last one should match new_end and its top should
 630   // match new_top.
 631   assert(hr == NULL ||
 632          (hr->end() == new_end && hr->top() == new_top), "sanity");
 633   check_bitmaps("Humongous Region Allocation", first_hr);
 634 
 635   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 636   increase_used(first_hr->used());
 637   _humongous_set.add(first_hr);
 638 
 639   return new_obj;
 640 }
 641 
 642 // If could fit into free regions w/o expansion, try.
 643 // Otherwise, if can expand, do so.
 644 // Otherwise, if using ex regions might help, try with ex given back.
 645 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 646   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 647 
 648   verify_region_sets_optional();
 649 
 650   uint first = G1_NO_HRM_INDEX;
 651   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 652 
 653   if (obj_regions == 1) {
 654     // Only one region to allocate, try to use a fast path by directly allocating
 655     // from the free lists. Do not try to expand here, we will potentially do that
 656     // later.
 657     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 658     if (hr != NULL) {
 659       first = hr->hrm_index();
 660     }
 661   } else {
 662     // We can't allocate humongous regions spanning more than one region while
 663     // cleanupComplete() is running, since some of the regions we find to be
 664     // empty might not yet be added to the free list. It is not straightforward
 665     // to know in which list they are on so that we can remove them. We only
 666     // need to do this if we need to allocate more than one region to satisfy the
 667     // current humongous allocation request. If we are only allocating one region
 668     // we use the one-region region allocation code (see above), that already
 669     // potentially waits for regions from the secondary free list.
 670     wait_while_free_regions_coming();
 671     append_secondary_free_list_if_not_empty_with_lock();
 672 
 673     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 674     // are lucky enough to find some.
 675     first = _hrm.find_contiguous_only_empty(obj_regions);
 676     if (first != G1_NO_HRM_INDEX) {
 677       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 678     }
 679   }
 680 
 681   if (first == G1_NO_HRM_INDEX) {
 682     // Policy: We could not find enough regions for the humongous object in the
 683     // free list. Look through the heap to find a mix of free and uncommitted regions.
 684     // If so, try expansion.
 685     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 686     if (first != G1_NO_HRM_INDEX) {
 687       // We found something. Make sure these regions are committed, i.e. expand
 688       // the heap. Alternatively we could do a defragmentation GC.
 689       ergo_verbose1(ErgoHeapSizing,
 690                     "attempt heap expansion",
 691                     ergo_format_reason("humongous allocation request failed")
 692                     ergo_format_byte("allocation request"),
 693                     word_size * HeapWordSize);
 694 
 695       _hrm.expand_at(first, obj_regions);
 696       g1_policy()->record_new_heap_size(num_regions());
 697 
 698 #ifdef ASSERT
 699       for (uint i = first; i < first + obj_regions; ++i) {
 700         HeapRegion* hr = region_at(i);
 701         assert(hr->is_free(), "sanity");
 702         assert(hr->is_empty(), "sanity");
 703         assert(is_on_master_free_list(hr), "sanity");
 704       }
 705 #endif
 706       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 707     } else {
 708       // Policy: Potentially trigger a defragmentation GC.
 709     }
 710   }
 711 
 712   HeapWord* result = NULL;
 713   if (first != G1_NO_HRM_INDEX) {
 714     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 715                                                        word_size, context);
 716     assert(result != NULL, "it should always return a valid result");
 717 
 718     // A successful humongous object allocation changes the used space
 719     // information of the old generation so we need to recalculate the
 720     // sizes and update the jstat counters here.
 721     g1mm()->update_sizes();
 722   }
 723 
 724   verify_region_sets_optional();
 725 
 726   return result;
 727 }
 728 
 729 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 730   assert_heap_not_locked_and_not_at_safepoint();
 731   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 732 
 733   uint dummy_gc_count_before;
 734   uint dummy_gclocker_retry_count = 0;
 735   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 736 }
 737 
 738 HeapWord*
 739 G1CollectedHeap::mem_allocate(size_t word_size,
 740                               bool*  gc_overhead_limit_was_exceeded) {
 741   assert_heap_not_locked_and_not_at_safepoint();
 742 
 743   // Loop until the allocation is satisfied, or unsatisfied after GC.
 744   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 745     uint gc_count_before;
 746 
 747     HeapWord* result = NULL;
 748     if (!is_humongous(word_size)) {
 749       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 750     } else {
 751       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 752     }
 753     if (result != NULL) {
 754       return result;
 755     }
 756 
 757     // Create the garbage collection operation...
 758     VM_G1CollectForAllocation op(gc_count_before, word_size);
 759     op.set_allocation_context(AllocationContext::current());
 760 
 761     // ...and get the VM thread to execute it.
 762     VMThread::execute(&op);
 763 
 764     if (op.prologue_succeeded() && op.pause_succeeded()) {
 765       // If the operation was successful we'll return the result even
 766       // if it is NULL. If the allocation attempt failed immediately
 767       // after a Full GC, it's unlikely we'll be able to allocate now.
 768       HeapWord* result = op.result();
 769       if (result != NULL && !is_humongous(word_size)) {
 770         // Allocations that take place on VM operations do not do any
 771         // card dirtying and we have to do it here. We only have to do
 772         // this for non-humongous allocations, though.
 773         dirty_young_block(result, word_size);
 774       }
 775       return result;
 776     } else {
 777       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 778         return NULL;
 779       }
 780       assert(op.result() == NULL,
 781              "the result should be NULL if the VM op did not succeed");
 782     }
 783 
 784     // Give a warning if we seem to be looping forever.
 785     if ((QueuedAllocationWarningCount > 0) &&
 786         (try_count % QueuedAllocationWarningCount == 0)) {
 787       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 788     }
 789   }
 790 
 791   ShouldNotReachHere();
 792   return NULL;
 793 }
 794 
 795 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 796                                                    AllocationContext_t context,
 797                                                    uint* gc_count_before_ret,
 798                                                    uint* gclocker_retry_count_ret) {
 799   // Make sure you read the note in attempt_allocation_humongous().
 800 
 801   assert_heap_not_locked_and_not_at_safepoint();
 802   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 803          "be called for humongous allocation requests");
 804 
 805   // We should only get here after the first-level allocation attempt
 806   // (attempt_allocation()) failed to allocate.
 807 
 808   // We will loop until a) we manage to successfully perform the
 809   // allocation or b) we successfully schedule a collection which
 810   // fails to perform the allocation. b) is the only case when we'll
 811   // return NULL.
 812   HeapWord* result = NULL;
 813   for (int try_count = 1; /* we'll return */; try_count += 1) {
 814     bool should_try_gc;
 815     uint gc_count_before;
 816 
 817     {
 818       MutexLockerEx x(Heap_lock);
 819       result = _allocator->attempt_allocation_locked(word_size, context);
 820       if (result != NULL) {
 821         return result;
 822       }
 823 
 824       if (GC_locker::is_active_and_needs_gc()) {
 825         if (g1_policy()->can_expand_young_list()) {
 826           // No need for an ergo verbose message here,
 827           // can_expand_young_list() does this when it returns true.
 828           result = _allocator->attempt_allocation_force(word_size, context);
 829           if (result != NULL) {
 830             return result;
 831           }
 832         }
 833         should_try_gc = false;
 834       } else {
 835         // The GCLocker may not be active but the GCLocker initiated
 836         // GC may not yet have been performed (GCLocker::needs_gc()
 837         // returns true). In this case we do not try this GC and
 838         // wait until the GCLocker initiated GC is performed, and
 839         // then retry the allocation.
 840         if (GC_locker::needs_gc()) {
 841           should_try_gc = false;
 842         } else {
 843           // Read the GC count while still holding the Heap_lock.
 844           gc_count_before = total_collections();
 845           should_try_gc = true;
 846         }
 847       }
 848     }
 849 
 850     if (should_try_gc) {
 851       bool succeeded;
 852       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 853                                    GCCause::_g1_inc_collection_pause);
 854       if (result != NULL) {
 855         assert(succeeded, "only way to get back a non-NULL result");
 856         return result;
 857       }
 858 
 859       if (succeeded) {
 860         // If we get here we successfully scheduled a collection which
 861         // failed to allocate. No point in trying to allocate
 862         // further. We'll just return NULL.
 863         MutexLockerEx x(Heap_lock);
 864         *gc_count_before_ret = total_collections();
 865         return NULL;
 866       }
 867     } else {
 868       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 869         MutexLockerEx x(Heap_lock);
 870         *gc_count_before_ret = total_collections();
 871         return NULL;
 872       }
 873       // The GCLocker is either active or the GCLocker initiated
 874       // GC has not yet been performed. Stall until it is and
 875       // then retry the allocation.
 876       GC_locker::stall_until_clear();
 877       (*gclocker_retry_count_ret) += 1;
 878     }
 879 
 880     // We can reach here if we were unsuccessful in scheduling a
 881     // collection (because another thread beat us to it) or if we were
 882     // stalled due to the GC locker. In either can we should retry the
 883     // allocation attempt in case another thread successfully
 884     // performed a collection and reclaimed enough space. We do the
 885     // first attempt (without holding the Heap_lock) here and the
 886     // follow-on attempt will be at the start of the next loop
 887     // iteration (after taking the Heap_lock).
 888     result = _allocator->attempt_allocation(word_size, context);
 889     if (result != NULL) {
 890       return result;
 891     }
 892 
 893     // Give a warning if we seem to be looping forever.
 894     if ((QueuedAllocationWarningCount > 0) &&
 895         (try_count % QueuedAllocationWarningCount == 0)) {
 896       warning("G1CollectedHeap::attempt_allocation_slow() "
 897               "retries %d times", try_count);
 898     }
 899   }
 900 
 901   ShouldNotReachHere();
 902   return NULL;
 903 }
 904 
 905 void G1CollectedHeap::begin_archive_alloc_range() {
 906   assert_at_safepoint(true /* should_be_vm_thread */);
 907   if (_archive_allocator == NULL) {
 908     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 909   }
 910 }
 911 
 912 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 913   // Allocations in archive regions cannot be of a size that would be considered
 914   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 915   // may be different at archive-restore time.
 916   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 917 }
 918 
 919 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 920   assert_at_safepoint(true /* should_be_vm_thread */);
 921   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 922   if (is_archive_alloc_too_large(word_size)) {
 923     return NULL;
 924   }
 925   return _archive_allocator->archive_mem_allocate(word_size);
 926 }
 927 
 928 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 929                                               size_t end_alignment_in_bytes) {
 930   assert_at_safepoint(true /* should_be_vm_thread */);
 931   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 932 
 933   // Call complete_archive to do the real work, filling in the MemRegion
 934   // array with the archive regions.
 935   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 936   delete _archive_allocator;
 937   _archive_allocator = NULL;
 938 }
 939 
 940 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 941   assert(ranges != NULL, "MemRegion array NULL");
 942   assert(count != 0, "No MemRegions provided");
 943   MemRegion reserved = _hrm.reserved();
 944   for (size_t i = 0; i < count; i++) {
 945     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 946       return false;
 947     }
 948   }
 949   return true;
 950 }
 951 
 952 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 953   assert(!is_init_completed(), "Expect to be called at JVM init time");
 954   assert(ranges != NULL, "MemRegion array NULL");
 955   assert(count != 0, "No MemRegions provided");
 956   MutexLockerEx x(Heap_lock);
 957 
 958   MemRegion reserved = _hrm.reserved();
 959   HeapWord* prev_last_addr = NULL;
 960   HeapRegion* prev_last_region = NULL;
 961 
 962   // Temporarily disable pretouching of heap pages. This interface is used
 963   // when mmap'ing archived heap data in, so pre-touching is wasted.
 964   FlagSetting fs(AlwaysPreTouch, false);
 965 
 966   // Enable archive object checking in G1MarkSweep. We have to let it know
 967   // about each archive range, so that objects in those ranges aren't marked.
 968   G1MarkSweep::enable_archive_object_check();
 969 
 970   // For each specified MemRegion range, allocate the corresponding G1
 971   // regions and mark them as archive regions. We expect the ranges in
 972   // ascending starting address order, without overlap.
 973   for (size_t i = 0; i < count; i++) {
 974     MemRegion curr_range = ranges[i];
 975     HeapWord* start_address = curr_range.start();
 976     size_t word_size = curr_range.word_size();
 977     HeapWord* last_address = curr_range.last();
 978     size_t commits = 0;
 979 
 980     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 981               err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 982               p2i(start_address), p2i(last_address)));
 983     guarantee(start_address > prev_last_addr,
 984               err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 985               p2i(start_address), p2i(prev_last_addr)));
 986     prev_last_addr = last_address;
 987 
 988     // Check for ranges that start in the same G1 region in which the previous
 989     // range ended, and adjust the start address so we don't try to allocate
 990     // the same region again. If the current range is entirely within that
 991     // region, skip it, just adjusting the recorded top.
 992     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 993     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 994       start_address = start_region->end();
 995       if (start_address > last_address) {
 996         increase_used(word_size * HeapWordSize);
 997         start_region->set_top(last_address + 1);
 998         continue;
 999       }
1000       start_region->set_top(start_address);
1001       curr_range = MemRegion(start_address, last_address + 1);
1002       start_region = _hrm.addr_to_region(start_address);
1003     }
1004 
1005     // Perform the actual region allocation, exiting if it fails.
1006     // Then note how much new space we have allocated.
1007     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1008       return false;
1009     }
1010     increase_used(word_size * HeapWordSize);
1011     if (commits != 0) {
1012       ergo_verbose1(ErgoHeapSizing,
1013                     "attempt heap expansion",
1014                     ergo_format_reason("allocate archive regions")
1015                     ergo_format_byte("total size"),
1016                     HeapRegion::GrainWords * HeapWordSize * commits);
1017     }
1018 
1019     // Mark each G1 region touched by the range as archive, add it to the old set,
1020     // and set the allocation context and top.
1021     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1022     HeapRegion* last_region = _hrm.addr_to_region(last_address);
1023     prev_last_region = last_region;
1024 
1025     while (curr_region != NULL) {
1026       assert(curr_region->is_empty() && !curr_region->is_pinned(),
1027              err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1028       _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1029       curr_region->set_allocation_context(AllocationContext::system());
1030       curr_region->set_archive();
1031       _old_set.add(curr_region);
1032       if (curr_region != last_region) {
1033         curr_region->set_top(curr_region->end());
1034         curr_region = _hrm.next_region_in_heap(curr_region);
1035       } else {
1036         curr_region->set_top(last_address + 1);
1037         curr_region = NULL;
1038       }
1039     }
1040 
1041     // Notify mark-sweep of the archive range.
1042     G1MarkSweep::set_range_archive(curr_range, true);
1043   }
1044   return true;
1045 }
1046 
1047 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1048   assert(!is_init_completed(), "Expect to be called at JVM init time");
1049   assert(ranges != NULL, "MemRegion array NULL");
1050   assert(count != 0, "No MemRegions provided");
1051   MemRegion reserved = _hrm.reserved();
1052   HeapWord *prev_last_addr = NULL;
1053   HeapRegion* prev_last_region = NULL;
1054 
1055   // For each MemRegion, create filler objects, if needed, in the G1 regions
1056   // that contain the address range. The address range actually within the
1057   // MemRegion will not be modified. That is assumed to have been initialized
1058   // elsewhere, probably via an mmap of archived heap data.
1059   MutexLockerEx x(Heap_lock);
1060   for (size_t i = 0; i < count; i++) {
1061     HeapWord* start_address = ranges[i].start();
1062     HeapWord* last_address = ranges[i].last();
1063 
1064     assert(reserved.contains(start_address) && reserved.contains(last_address),
1065            err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1066                    p2i(start_address), p2i(last_address)));
1067     assert(start_address > prev_last_addr,
1068            err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1069                    p2i(start_address), p2i(prev_last_addr)));
1070 
1071     HeapRegion* start_region = _hrm.addr_to_region(start_address);
1072     HeapRegion* last_region = _hrm.addr_to_region(last_address);
1073     HeapWord* bottom_address = start_region->bottom();
1074 
1075     // Check for a range beginning in the same region in which the
1076     // previous one ended.
1077     if (start_region == prev_last_region) {
1078       bottom_address = prev_last_addr + 1;
1079     }
1080 
1081     // Verify that the regions were all marked as archive regions by
1082     // alloc_archive_regions.
1083     HeapRegion* curr_region = start_region;
1084     while (curr_region != NULL) {
1085       guarantee(curr_region->is_archive(),
1086                 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1087       if (curr_region != last_region) {
1088         curr_region = _hrm.next_region_in_heap(curr_region);
1089       } else {
1090         curr_region = NULL;
1091       }
1092     }
1093 
1094     prev_last_addr = last_address;
1095     prev_last_region = last_region;
1096 
1097     // Fill the memory below the allocated range with dummy object(s),
1098     // if the region bottom does not match the range start, or if the previous
1099     // range ended within the same G1 region, and there is a gap.
1100     if (start_address != bottom_address) {
1101       size_t fill_size = pointer_delta(start_address, bottom_address);
1102       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1103       increase_used(fill_size * HeapWordSize);
1104     }
1105   }
1106 }
1107 
1108 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1109                                                      uint* gc_count_before_ret,
1110                                                      uint* gclocker_retry_count_ret) {
1111   assert_heap_not_locked_and_not_at_safepoint();
1112   assert(!is_humongous(word_size), "attempt_allocation() should not "
1113          "be called for humongous allocation requests");
1114 
1115   AllocationContext_t context = AllocationContext::current();
1116   HeapWord* result = _allocator->attempt_allocation(word_size, context);
1117 
1118   if (result == NULL) {
1119     result = attempt_allocation_slow(word_size,
1120                                      context,
1121                                      gc_count_before_ret,
1122                                      gclocker_retry_count_ret);
1123   }
1124   assert_heap_not_locked();
1125   if (result != NULL) {
1126     dirty_young_block(result, word_size);
1127   }
1128   return result;
1129 }
1130 
1131 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
1132   assert(!is_init_completed(), "Expect to be called at JVM init time");
1133   assert(ranges != NULL, "MemRegion array NULL");
1134   assert(count != 0, "No MemRegions provided");
1135   MemRegion reserved = _hrm.reserved();
1136   HeapWord* prev_last_addr = NULL;
1137   HeapRegion* prev_last_region = NULL;
1138   size_t size_used = 0;
1139   size_t uncommitted_regions = 0;
1140 
1141   // For each Memregion, free the G1 regions that constitute it, and 
1142   // notify mark-sweep that the range is no longer to be considered 'archive.' 
1143   MutexLockerEx x(Heap_lock);
1144   for (size_t i = 0; i < count; i++) {
1145     HeapWord* start_address = ranges[i].start();
1146     HeapWord* last_address = ranges[i].last();
1147 
1148     assert(reserved.contains(start_address) && reserved.contains(last_address),
1149            err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1150                    p2i(start_address), p2i(last_address)));
1151     assert(start_address > prev_last_addr,
1152            err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1153                    p2i(start_address), p2i(prev_last_addr)));
1154     size_used += ranges[i].byte_size();
1155     prev_last_addr = last_address;
1156 
1157     HeapRegion* start_region = _hrm.addr_to_region(start_address);
1158     HeapRegion* last_region = _hrm.addr_to_region(last_address);
1159 
1160     // Check for ranges that start in the same G1 region in which the previous
1161     // range ended, and adjust the start address so we don't try to free
1162     // the same region again. If the current range is entirely within that
1163     // region, skip it.
1164     if (start_region == prev_last_region) {
1165       start_address = start_region->end();
1166       if (start_address > last_address) {
1167         continue;
1168       }
1169       start_region = _hrm.addr_to_region(start_address);
1170     }
1171     prev_last_region = last_region;
1172 
1173     // After verifying that each region was marked as an archive region by
1174     // alloc_archive_regions, set it free and empty and uncommit it. 
1175     HeapRegion* curr_region = start_region;
1176     while (curr_region != NULL) {
1177       guarantee(curr_region->is_archive(),
1178                 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1179       uint curr_index = curr_region->hrm_index();
1180       _old_set.remove(curr_region);
1181       curr_region->set_free();
1182       curr_region->set_top(curr_region->bottom());
1183       if (curr_region != last_region) {
1184         curr_region = _hrm.next_region_in_heap(curr_region);
1185       } else {
1186         curr_region = NULL;
1187       }
1188       _hrm.shrink_at(curr_index, 1);
1189       uncommitted_regions++;
1190     }
1191 
1192     // Notify mark-sweep that this is no longer an archive range.
1193     G1MarkSweep::set_range_archive(ranges[i], false);
1194   }
1195 
1196   if (uncommitted_regions != 0) {
1197     ergo_verbose1(ErgoHeapSizing,
1198                   "attempt heap shrinking",
1199                   ergo_format_reason("uncommitted archive regions")
1200                   ergo_format_byte("total size"),
1201                   HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1202   }
1203   decrease_used(size_used);
1204 }
1205 
1206 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1207                                                         uint* gc_count_before_ret,
1208                                                         uint* gclocker_retry_count_ret) {
1209   // The structure of this method has a lot of similarities to
1210   // attempt_allocation_slow(). The reason these two were not merged
1211   // into a single one is that such a method would require several "if
1212   // allocation is not humongous do this, otherwise do that"
1213   // conditional paths which would obscure its flow. In fact, an early
1214   // version of this code did use a unified method which was harder to
1215   // follow and, as a result, it had subtle bugs that were hard to
1216   // track down. So keeping these two methods separate allows each to
1217   // be more readable. It will be good to keep these two in sync as
1218   // much as possible.
1219 
1220   assert_heap_not_locked_and_not_at_safepoint();
1221   assert(is_humongous(word_size), "attempt_allocation_humongous() "
1222          "should only be called for humongous allocations");
1223 
1224   // Humongous objects can exhaust the heap quickly, so we should check if we
1225   // need to start a marking cycle at each humongous object allocation. We do
1226   // the check before we do the actual allocation. The reason for doing it
1227   // before the allocation is that we avoid having to keep track of the newly
1228   // allocated memory while we do a GC.
1229   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1230                                            word_size)) {
1231     collect(GCCause::_g1_humongous_allocation);
1232   }
1233 
1234   // We will loop until a) we manage to successfully perform the
1235   // allocation or b) we successfully schedule a collection which
1236   // fails to perform the allocation. b) is the only case when we'll
1237   // return NULL.
1238   HeapWord* result = NULL;
1239   for (int try_count = 1; /* we'll return */; try_count += 1) {
1240     bool should_try_gc;
1241     uint gc_count_before;
1242 
1243     {
1244       MutexLockerEx x(Heap_lock);
1245 
1246       // Given that humongous objects are not allocated in young
1247       // regions, we'll first try to do the allocation without doing a
1248       // collection hoping that there's enough space in the heap.
1249       result = humongous_obj_allocate(word_size, AllocationContext::current());
1250       if (result != NULL) {
1251         return result;
1252       }
1253 
1254       if (GC_locker::is_active_and_needs_gc()) {
1255         should_try_gc = false;
1256       } else {
1257          // The GCLocker may not be active but the GCLocker initiated
1258         // GC may not yet have been performed (GCLocker::needs_gc()
1259         // returns true). In this case we do not try this GC and
1260         // wait until the GCLocker initiated GC is performed, and
1261         // then retry the allocation.
1262         if (GC_locker::needs_gc()) {
1263           should_try_gc = false;
1264         } else {
1265           // Read the GC count while still holding the Heap_lock.
1266           gc_count_before = total_collections();
1267           should_try_gc = true;
1268         }
1269       }
1270     }
1271 
1272     if (should_try_gc) {
1273       // If we failed to allocate the humongous object, we should try to
1274       // do a collection pause (if we're allowed) in case it reclaims
1275       // enough space for the allocation to succeed after the pause.
1276 
1277       bool succeeded;
1278       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1279                                    GCCause::_g1_humongous_allocation);
1280       if (result != NULL) {
1281         assert(succeeded, "only way to get back a non-NULL result");
1282         return result;
1283       }
1284 
1285       if (succeeded) {
1286         // If we get here we successfully scheduled a collection which
1287         // failed to allocate. No point in trying to allocate
1288         // further. We'll just return NULL.
1289         MutexLockerEx x(Heap_lock);
1290         *gc_count_before_ret = total_collections();
1291         return NULL;
1292       }
1293     } else {
1294       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1295         MutexLockerEx x(Heap_lock);
1296         *gc_count_before_ret = total_collections();
1297         return NULL;
1298       }
1299       // The GCLocker is either active or the GCLocker initiated
1300       // GC has not yet been performed. Stall until it is and
1301       // then retry the allocation.
1302       GC_locker::stall_until_clear();
1303       (*gclocker_retry_count_ret) += 1;
1304     }
1305 
1306     // We can reach here if we were unsuccessful in scheduling a
1307     // collection (because another thread beat us to it) or if we were
1308     // stalled due to the GC locker. In either can we should retry the
1309     // allocation attempt in case another thread successfully
1310     // performed a collection and reclaimed enough space.  Give a
1311     // warning if we seem to be looping forever.
1312 
1313     if ((QueuedAllocationWarningCount > 0) &&
1314         (try_count % QueuedAllocationWarningCount == 0)) {
1315       warning("G1CollectedHeap::attempt_allocation_humongous() "
1316               "retries %d times", try_count);
1317     }
1318   }
1319 
1320   ShouldNotReachHere();
1321   return NULL;
1322 }
1323 
1324 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1325                                                            AllocationContext_t context,
1326                                                            bool expect_null_mutator_alloc_region) {
1327   assert_at_safepoint(true /* should_be_vm_thread */);
1328   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1329          "the current alloc region was unexpectedly found to be non-NULL");
1330 
1331   if (!is_humongous(word_size)) {
1332     return _allocator->attempt_allocation_locked(word_size, context);
1333   } else {
1334     HeapWord* result = humongous_obj_allocate(word_size, context);
1335     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1336       collector_state()->set_initiate_conc_mark_if_possible(true);
1337     }
1338     return result;
1339   }
1340 
1341   ShouldNotReachHere();
1342 }
1343 
1344 class PostMCRemSetClearClosure: public HeapRegionClosure {
1345   G1CollectedHeap* _g1h;
1346   ModRefBarrierSet* _mr_bs;
1347 public:
1348   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1349     _g1h(g1h), _mr_bs(mr_bs) {}
1350 
1351   bool doHeapRegion(HeapRegion* r) {
1352     HeapRegionRemSet* hrrs = r->rem_set();
1353 
1354     if (r->is_continues_humongous()) {
1355       // We'll assert that the strong code root list and RSet is empty
1356       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1357       assert(hrrs->occupied() == 0, "RSet should be empty");
1358       return false;
1359     }
1360 
1361     _g1h->reset_gc_time_stamps(r);
1362     hrrs->clear();
1363     // You might think here that we could clear just the cards
1364     // corresponding to the used region.  But no: if we leave a dirty card
1365     // in a region we might allocate into, then it would prevent that card
1366     // from being enqueued, and cause it to be missed.
1367     // Re: the performance cost: we shouldn't be doing full GC anyway!
1368     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1369 
1370     return false;
1371   }
1372 };
1373 
1374 void G1CollectedHeap::clear_rsets_post_compaction() {
1375   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1376   heap_region_iterate(&rs_clear);
1377 }
1378 
1379 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1380   G1CollectedHeap*   _g1h;
1381   UpdateRSOopClosure _cl;
1382 public:
1383   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1384     _cl(g1->g1_rem_set(), worker_i),
1385     _g1h(g1)
1386   { }
1387 
1388   bool doHeapRegion(HeapRegion* r) {
1389     if (!r->is_continues_humongous()) {
1390       _cl.set_from(r);
1391       r->oop_iterate(&_cl);
1392     }
1393     return false;
1394   }
1395 };
1396 
1397 class ParRebuildRSTask: public AbstractGangTask {
1398   G1CollectedHeap* _g1;
1399   HeapRegionClaimer _hrclaimer;
1400 
1401 public:
1402   ParRebuildRSTask(G1CollectedHeap* g1) :
1403       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1404 
1405   void work(uint worker_id) {
1406     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1407     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1408   }
1409 };
1410 
1411 class PostCompactionPrinterClosure: public HeapRegionClosure {
1412 private:
1413   G1HRPrinter* _hr_printer;
1414 public:
1415   bool doHeapRegion(HeapRegion* hr) {
1416     assert(!hr->is_young(), "not expecting to find young regions");
1417     if (hr->is_free()) {
1418       // We only generate output for non-empty regions.
1419     } else if (hr->is_starts_humongous()) {
1420       if (hr->region_num() == 1) {
1421         // single humongous region
1422         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1423       } else {
1424         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1425       }
1426     } else if (hr->is_continues_humongous()) {
1427       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1428     } else if (hr->is_archive()) {
1429       _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1430     } else if (hr->is_old()) {
1431       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1432     } else {
1433       ShouldNotReachHere();
1434     }
1435     return false;
1436   }
1437 
1438   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1439     : _hr_printer(hr_printer) { }
1440 };
1441 
1442 void G1CollectedHeap::print_hrm_post_compaction() {
1443   PostCompactionPrinterClosure cl(hr_printer());
1444   heap_region_iterate(&cl);
1445 }
1446 
1447 bool G1CollectedHeap::do_collection(bool explicit_gc,
1448                                     bool clear_all_soft_refs,
1449                                     size_t word_size) {
1450   assert_at_safepoint(true /* should_be_vm_thread */);
1451 
1452   if (GC_locker::check_active_before_gc()) {
1453     return false;
1454   }
1455 
1456   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1457   gc_timer->register_gc_start();
1458 
1459   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1460   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1461 
1462   SvcGCMarker sgcm(SvcGCMarker::FULL);
1463   ResourceMark rm;
1464 
1465   G1Log::update_level();
1466   print_heap_before_gc();
1467   trace_heap_before_gc(gc_tracer);
1468 
1469   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1470 
1471   verify_region_sets_optional();
1472 
1473   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1474                            collector_policy()->should_clear_all_soft_refs();
1475 
1476   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1477 
1478   {
1479     IsGCActiveMark x;
1480 
1481     // Timing
1482     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1483     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1484 
1485     {
1486       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1487       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1488       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1489 
1490       g1_policy()->record_full_collection_start();
1491 
1492       // Note: When we have a more flexible GC logging framework that
1493       // allows us to add optional attributes to a GC log record we
1494       // could consider timing and reporting how long we wait in the
1495       // following two methods.
1496       wait_while_free_regions_coming();
1497       // If we start the compaction before the CM threads finish
1498       // scanning the root regions we might trip them over as we'll
1499       // be moving objects / updating references. So let's wait until
1500       // they are done. By telling them to abort, they should complete
1501       // early.
1502       _cm->root_regions()->abort();
1503       _cm->root_regions()->wait_until_scan_finished();
1504       append_secondary_free_list_if_not_empty_with_lock();
1505 
1506       gc_prologue(true);
1507       increment_total_collections(true /* full gc */);
1508       increment_old_marking_cycles_started();
1509 
1510       assert(used() == recalculate_used(), "Should be equal");
1511 
1512       verify_before_gc();
1513 
1514       check_bitmaps("Full GC Start");
1515       pre_full_gc_dump(gc_timer);
1516 
1517       COMPILER2_PRESENT(DerivedPointerTable::clear());
1518 
1519       // Disable discovery and empty the discovered lists
1520       // for the CM ref processor.
1521       ref_processor_cm()->disable_discovery();
1522       ref_processor_cm()->abandon_partial_discovery();
1523       ref_processor_cm()->verify_no_references_recorded();
1524 
1525       // Abandon current iterations of concurrent marking and concurrent
1526       // refinement, if any are in progress. We have to do this before
1527       // wait_until_scan_finished() below.
1528       concurrent_mark()->abort();
1529 
1530       // Make sure we'll choose a new allocation region afterwards.
1531       _allocator->release_mutator_alloc_region();
1532       _allocator->abandon_gc_alloc_regions();
1533       g1_rem_set()->cleanupHRRS();
1534 
1535       // We should call this after we retire any currently active alloc
1536       // regions so that all the ALLOC / RETIRE events are generated
1537       // before the start GC event.
1538       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1539 
1540       // We may have added regions to the current incremental collection
1541       // set between the last GC or pause and now. We need to clear the
1542       // incremental collection set and then start rebuilding it afresh
1543       // after this full GC.
1544       abandon_collection_set(g1_policy()->inc_cset_head());
1545       g1_policy()->clear_incremental_cset();
1546       g1_policy()->stop_incremental_cset_building();
1547 
1548       tear_down_region_sets(false /* free_list_only */);
1549       collector_state()->set_gcs_are_young(true);
1550 
1551       // See the comments in g1CollectedHeap.hpp and
1552       // G1CollectedHeap::ref_processing_init() about
1553       // how reference processing currently works in G1.
1554 
1555       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1556       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1557 
1558       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1559       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1560 
1561       ref_processor_stw()->enable_discovery();
1562       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1563 
1564       // Do collection work
1565       {
1566         HandleMark hm;  // Discard invalid handles created during gc
1567         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1568       }
1569 
1570       assert(num_free_regions() == 0, "we should not have added any free regions");
1571       rebuild_region_sets(false /* free_list_only */);
1572 
1573       // Enqueue any discovered reference objects that have
1574       // not been removed from the discovered lists.
1575       ref_processor_stw()->enqueue_discovered_references();
1576 
1577       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1578 
1579       MemoryService::track_memory_usage();
1580 
1581       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1582       ref_processor_stw()->verify_no_references_recorded();
1583 
1584       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1585       ClassLoaderDataGraph::purge();
1586       MetaspaceAux::verify_metrics();
1587 
1588       // Note: since we've just done a full GC, concurrent
1589       // marking is no longer active. Therefore we need not
1590       // re-enable reference discovery for the CM ref processor.
1591       // That will be done at the start of the next marking cycle.
1592       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1593       ref_processor_cm()->verify_no_references_recorded();
1594 
1595       reset_gc_time_stamp();
1596       // Since everything potentially moved, we will clear all remembered
1597       // sets, and clear all cards.  Later we will rebuild remembered
1598       // sets. We will also reset the GC time stamps of the regions.
1599       clear_rsets_post_compaction();
1600       check_gc_time_stamps();
1601 
1602       // Resize the heap if necessary.
1603       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1604 
1605       if (_hr_printer.is_active()) {
1606         // We should do this after we potentially resize the heap so
1607         // that all the COMMIT / UNCOMMIT events are generated before
1608         // the end GC event.
1609 
1610         print_hrm_post_compaction();
1611         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1612       }
1613 
1614       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1615       if (hot_card_cache->use_cache()) {
1616         hot_card_cache->reset_card_counts();
1617         hot_card_cache->reset_hot_cache();
1618       }
1619 
1620       // Rebuild remembered sets of all regions.
1621       uint n_workers =
1622         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1623                                                 workers()->active_workers(),
1624                                                 Threads::number_of_non_daemon_threads());
1625       workers()->set_active_workers(n_workers);
1626 
1627       ParRebuildRSTask rebuild_rs_task(this);
1628       workers()->run_task(&rebuild_rs_task);
1629 
1630       // Rebuild the strong code root lists for each region
1631       rebuild_strong_code_roots();
1632 
1633       if (true) { // FIXME
1634         MetaspaceGC::compute_new_size();
1635       }
1636 
1637 #ifdef TRACESPINNING
1638       ParallelTaskTerminator::print_termination_counts();
1639 #endif
1640 
1641       // Discard all rset updates
1642       JavaThread::dirty_card_queue_set().abandon_logs();
1643       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1644 
1645       _young_list->reset_sampled_info();
1646       // At this point there should be no regions in the
1647       // entire heap tagged as young.
1648       assert(check_young_list_empty(true /* check_heap */),
1649              "young list should be empty at this point");
1650 
1651       // Update the number of full collections that have been completed.
1652       increment_old_marking_cycles_completed(false /* concurrent */);
1653 
1654       _hrm.verify_optional();
1655       verify_region_sets_optional();
1656 
1657       verify_after_gc();
1658 
1659       // Clear the previous marking bitmap, if needed for bitmap verification.
1660       // Note we cannot do this when we clear the next marking bitmap in
1661       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1662       // objects marked during a full GC against the previous bitmap.
1663       // But we need to clear it before calling check_bitmaps below since
1664       // the full GC has compacted objects and updated TAMS but not updated
1665       // the prev bitmap.
1666       if (G1VerifyBitmaps) {
1667         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1668       }
1669       check_bitmaps("Full GC End");
1670 
1671       // Start a new incremental collection set for the next pause
1672       assert(g1_policy()->collection_set() == NULL, "must be");
1673       g1_policy()->start_incremental_cset_building();
1674 
1675       clear_cset_fast_test();
1676 
1677       _allocator->init_mutator_alloc_region();
1678 
1679       g1_policy()->record_full_collection_end();
1680 
1681       if (G1Log::fine()) {
1682         g1_policy()->print_heap_transition();
1683       }
1684 
1685       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1686       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1687       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1688       // before any GC notifications are raised.
1689       g1mm()->update_sizes();
1690 
1691       gc_epilogue(true);
1692     }
1693 
1694     if (G1Log::finer()) {
1695       g1_policy()->print_detailed_heap_transition(true /* full */);
1696     }
1697 
1698     print_heap_after_gc();
1699     trace_heap_after_gc(gc_tracer);
1700 
1701     post_full_gc_dump(gc_timer);
1702 
1703     gc_timer->register_gc_end();
1704     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1705   }
1706 
1707   return true;
1708 }
1709 
1710 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1711   // do_collection() will return whether it succeeded in performing
1712   // the GC. Currently, there is no facility on the
1713   // do_full_collection() API to notify the caller than the collection
1714   // did not succeed (e.g., because it was locked out by the GC
1715   // locker). So, right now, we'll ignore the return value.
1716   bool dummy = do_collection(true,                /* explicit_gc */
1717                              clear_all_soft_refs,
1718                              0                    /* word_size */);
1719 }
1720 
1721 // This code is mostly copied from TenuredGeneration.
1722 void
1723 G1CollectedHeap::
1724 resize_if_necessary_after_full_collection(size_t word_size) {
1725   // Include the current allocation, if any, and bytes that will be
1726   // pre-allocated to support collections, as "used".
1727   const size_t used_after_gc = used();
1728   const size_t capacity_after_gc = capacity();
1729   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1730 
1731   // This is enforced in arguments.cpp.
1732   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1733          "otherwise the code below doesn't make sense");
1734 
1735   // We don't have floating point command-line arguments
1736   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1737   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1738   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1739   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1740 
1741   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1742   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1743 
1744   // We have to be careful here as these two calculations can overflow
1745   // 32-bit size_t's.
1746   double used_after_gc_d = (double) used_after_gc;
1747   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1748   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1749 
1750   // Let's make sure that they are both under the max heap size, which
1751   // by default will make them fit into a size_t.
1752   double desired_capacity_upper_bound = (double) max_heap_size;
1753   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1754                                     desired_capacity_upper_bound);
1755   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1756                                     desired_capacity_upper_bound);
1757 
1758   // We can now safely turn them into size_t's.
1759   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1760   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1761 
1762   // This assert only makes sense here, before we adjust them
1763   // with respect to the min and max heap size.
1764   assert(minimum_desired_capacity <= maximum_desired_capacity,
1765          err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1766                  "maximum_desired_capacity = " SIZE_FORMAT,
1767                  minimum_desired_capacity, maximum_desired_capacity));
1768 
1769   // Should not be greater than the heap max size. No need to adjust
1770   // it with respect to the heap min size as it's a lower bound (i.e.,
1771   // we'll try to make the capacity larger than it, not smaller).
1772   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1773   // Should not be less than the heap min size. No need to adjust it
1774   // with respect to the heap max size as it's an upper bound (i.e.,
1775   // we'll try to make the capacity smaller than it, not greater).
1776   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1777 
1778   if (capacity_after_gc < minimum_desired_capacity) {
1779     // Don't expand unless it's significant
1780     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1781     ergo_verbose4(ErgoHeapSizing,
1782                   "attempt heap expansion",
1783                   ergo_format_reason("capacity lower than "
1784                                      "min desired capacity after Full GC")
1785                   ergo_format_byte("capacity")
1786                   ergo_format_byte("occupancy")
1787                   ergo_format_byte_perc("min desired capacity"),
1788                   capacity_after_gc, used_after_gc,
1789                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1790     expand(expand_bytes);
1791 
1792     // No expansion, now see if we want to shrink
1793   } else if (capacity_after_gc > maximum_desired_capacity) {
1794     // Capacity too large, compute shrinking size
1795     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1796     ergo_verbose4(ErgoHeapSizing,
1797                   "attempt heap shrinking",
1798                   ergo_format_reason("capacity higher than "
1799                                      "max desired capacity after Full GC")
1800                   ergo_format_byte("capacity")
1801                   ergo_format_byte("occupancy")
1802                   ergo_format_byte_perc("max desired capacity"),
1803                   capacity_after_gc, used_after_gc,
1804                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1805     shrink(shrink_bytes);
1806   }
1807 }
1808 
1809 
1810 HeapWord*
1811 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1812                                            AllocationContext_t context,
1813                                            bool* succeeded) {
1814   assert_at_safepoint(true /* should_be_vm_thread */);
1815 
1816   *succeeded = true;
1817   // Let's attempt the allocation first.
1818   HeapWord* result =
1819     attempt_allocation_at_safepoint(word_size,
1820                                     context,
1821                                     false /* expect_null_mutator_alloc_region */);
1822   if (result != NULL) {
1823     assert(*succeeded, "sanity");
1824     return result;
1825   }
1826 
1827   // In a G1 heap, we're supposed to keep allocation from failing by
1828   // incremental pauses.  Therefore, at least for now, we'll favor
1829   // expansion over collection.  (This might change in the future if we can
1830   // do something smarter than full collection to satisfy a failed alloc.)
1831   result = expand_and_allocate(word_size, context);
1832   if (result != NULL) {
1833     assert(*succeeded, "sanity");
1834     return result;
1835   }
1836 
1837   // Expansion didn't work, we'll try to do a Full GC.
1838   bool gc_succeeded = do_collection(false, /* explicit_gc */
1839                                     false, /* clear_all_soft_refs */
1840                                     word_size);
1841   if (!gc_succeeded) {
1842     *succeeded = false;
1843     return NULL;
1844   }
1845 
1846   // Retry the allocation
1847   result = attempt_allocation_at_safepoint(word_size,
1848                                            context,
1849                                            true /* expect_null_mutator_alloc_region */);
1850   if (result != NULL) {
1851     assert(*succeeded, "sanity");
1852     return result;
1853   }
1854 
1855   // Then, try a Full GC that will collect all soft references.
1856   gc_succeeded = do_collection(false, /* explicit_gc */
1857                                true,  /* clear_all_soft_refs */
1858                                word_size);
1859   if (!gc_succeeded) {
1860     *succeeded = false;
1861     return NULL;
1862   }
1863 
1864   // Retry the allocation once more
1865   result = attempt_allocation_at_safepoint(word_size,
1866                                            context,
1867                                            true /* expect_null_mutator_alloc_region */);
1868   if (result != NULL) {
1869     assert(*succeeded, "sanity");
1870     return result;
1871   }
1872 
1873   assert(!collector_policy()->should_clear_all_soft_refs(),
1874          "Flag should have been handled and cleared prior to this point");
1875 
1876   // What else?  We might try synchronous finalization later.  If the total
1877   // space available is large enough for the allocation, then a more
1878   // complete compaction phase than we've tried so far might be
1879   // appropriate.
1880   assert(*succeeded, "sanity");
1881   return NULL;
1882 }
1883 
1884 // Attempting to expand the heap sufficiently
1885 // to support an allocation of the given "word_size".  If
1886 // successful, perform the allocation and return the address of the
1887 // allocated block, or else "NULL".
1888 
1889 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1890   assert_at_safepoint(true /* should_be_vm_thread */);
1891 
1892   verify_region_sets_optional();
1893 
1894   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1895   ergo_verbose1(ErgoHeapSizing,
1896                 "attempt heap expansion",
1897                 ergo_format_reason("allocation request failed")
1898                 ergo_format_byte("allocation request"),
1899                 word_size * HeapWordSize);
1900   if (expand(expand_bytes)) {
1901     _hrm.verify_optional();
1902     verify_region_sets_optional();
1903     return attempt_allocation_at_safepoint(word_size,
1904                                            context,
1905                                            false /* expect_null_mutator_alloc_region */);
1906   }
1907   return NULL;
1908 }
1909 
1910 bool G1CollectedHeap::expand(size_t expand_bytes) {
1911   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1912   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1913                                        HeapRegion::GrainBytes);
1914   ergo_verbose2(ErgoHeapSizing,
1915                 "expand the heap",
1916                 ergo_format_byte("requested expansion amount")
1917                 ergo_format_byte("attempted expansion amount"),
1918                 expand_bytes, aligned_expand_bytes);
1919 
1920   if (is_maximal_no_gc()) {
1921     ergo_verbose0(ErgoHeapSizing,
1922                       "did not expand the heap",
1923                       ergo_format_reason("heap already fully expanded"));
1924     return false;
1925   }
1926 
1927   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1928   assert(regions_to_expand > 0, "Must expand by at least one region");
1929 
1930   uint expanded_by = _hrm.expand_by(regions_to_expand);
1931 
1932   if (expanded_by > 0) {
1933     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1934     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1935     g1_policy()->record_new_heap_size(num_regions());
1936   } else {
1937     ergo_verbose0(ErgoHeapSizing,
1938                   "did not expand the heap",
1939                   ergo_format_reason("heap expansion operation failed"));
1940     // The expansion of the virtual storage space was unsuccessful.
1941     // Let's see if it was because we ran out of swap.
1942     if (G1ExitOnExpansionFailure &&
1943         _hrm.available() >= regions_to_expand) {
1944       // We had head room...
1945       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1946     }
1947   }
1948   return regions_to_expand > 0;
1949 }
1950 
1951 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1952   size_t aligned_shrink_bytes =
1953     ReservedSpace::page_align_size_down(shrink_bytes);
1954   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1955                                          HeapRegion::GrainBytes);
1956   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1957 
1958   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1959   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1960 
1961   ergo_verbose3(ErgoHeapSizing,
1962                 "shrink the heap",
1963                 ergo_format_byte("requested shrinking amount")
1964                 ergo_format_byte("aligned shrinking amount")
1965                 ergo_format_byte("attempted shrinking amount"),
1966                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1967   if (num_regions_removed > 0) {
1968     g1_policy()->record_new_heap_size(num_regions());
1969   } else {
1970     ergo_verbose0(ErgoHeapSizing,
1971                   "did not shrink the heap",
1972                   ergo_format_reason("heap shrinking operation failed"));
1973   }
1974 }
1975 
1976 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1977   verify_region_sets_optional();
1978 
1979   // We should only reach here at the end of a Full GC which means we
1980   // should not not be holding to any GC alloc regions. The method
1981   // below will make sure of that and do any remaining clean up.
1982   _allocator->abandon_gc_alloc_regions();
1983 
1984   // Instead of tearing down / rebuilding the free lists here, we
1985   // could instead use the remove_all_pending() method on free_list to
1986   // remove only the ones that we need to remove.
1987   tear_down_region_sets(true /* free_list_only */);
1988   shrink_helper(shrink_bytes);
1989   rebuild_region_sets(true /* free_list_only */);
1990 
1991   _hrm.verify_optional();
1992   verify_region_sets_optional();
1993 }
1994 
1995 // Public methods.
1996 
1997 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1998 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1999 #endif // _MSC_VER
2000 
2001 
2002 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2003   CollectedHeap(),
2004   _g1_policy(policy_),
2005   _dirty_card_queue_set(false),
2006   _into_cset_dirty_card_queue_set(false),
2007   _is_alive_closure_cm(this),
2008   _is_alive_closure_stw(this),
2009   _ref_processor_cm(NULL),
2010   _ref_processor_stw(NULL),
2011   _bot_shared(NULL),
2012   _cg1r(NULL),
2013   _g1mm(NULL),
2014   _refine_cte_cl(NULL),
2015   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2016   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2017   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2018   _humongous_reclaim_candidates(),
2019   _has_humongous_reclaim_candidates(false),
2020   _archive_allocator(NULL),
2021   _free_regions_coming(false),
2022   _young_list(new YoungList(this)),
2023   _gc_time_stamp(0),
2024   _summary_bytes_used(0),
2025   _survivor_plab_stats(YoungPLABSize, PLABWeight),
2026   _old_plab_stats(OldPLABSize, PLABWeight),
2027   _expand_heap_after_alloc_failure(true),
2028   _surviving_young_words(NULL),
2029   _old_marking_cycles_started(0),
2030   _old_marking_cycles_completed(0),
2031   _heap_summary_sent(false),
2032   _in_cset_fast_test(),
2033   _dirty_cards_region_list(NULL),
2034   _worker_cset_start_region(NULL),
2035   _worker_cset_start_region_time_stamp(NULL),
2036   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2037   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2038   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2039   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2040 
2041   _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
2042                           /* are_GC_task_threads */true,
2043                           /* are_ConcurrentGC_threads */false);
2044   _workers->initialize_workers();
2045 
2046   _allocator = G1Allocator::create_allocator(this);
2047   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2048 
2049   // Override the default _filler_array_max_size so that no humongous filler
2050   // objects are created.
2051   _filler_array_max_size = _humongous_object_threshold_in_words;
2052 
2053   uint n_queues = ParallelGCThreads;
2054   _task_queues = new RefToScanQueueSet(n_queues);
2055 
2056   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2057   assert(n_rem_sets > 0, "Invariant.");
2058 
2059   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2060   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2061   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2062 
2063   for (uint i = 0; i < n_queues; i++) {
2064     RefToScanQueue* q = new RefToScanQueue();
2065     q->initialize();
2066     _task_queues->register_queue(i, q);
2067     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2068   }
2069   clear_cset_start_regions();
2070 
2071   // Initialize the G1EvacuationFailureALot counters and flags.
2072   NOT_PRODUCT(reset_evacuation_should_fail();)
2073 
2074   guarantee(_task_queues != NULL, "task_queues allocation failure.");
2075 }
2076 
2077 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2078                                                                  size_t size,
2079                                                                  size_t translation_factor) {
2080   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2081   // Allocate a new reserved space, preferring to use large pages.
2082   ReservedSpace rs(size, preferred_page_size);
2083   G1RegionToSpaceMapper* result  =
2084     G1RegionToSpaceMapper::create_mapper(rs,
2085                                          size,
2086                                          rs.alignment(),
2087                                          HeapRegion::GrainBytes,
2088                                          translation_factor,
2089                                          mtGC);
2090   if (TracePageSizes) {
2091     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2092                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2093   }
2094   return result;
2095 }
2096 
2097 jint G1CollectedHeap::initialize() {
2098   CollectedHeap::pre_initialize();
2099   os::enable_vtime();
2100 
2101   G1Log::init();
2102 
2103   // Necessary to satisfy locking discipline assertions.
2104 
2105   MutexLocker x(Heap_lock);
2106 
2107   // We have to initialize the printer before committing the heap, as
2108   // it will be used then.
2109   _hr_printer.set_active(G1PrintHeapRegions);
2110 
2111   // While there are no constraints in the GC code that HeapWordSize
2112   // be any particular value, there are multiple other areas in the
2113   // system which believe this to be true (e.g. oop->object_size in some
2114   // cases incorrectly returns the size in wordSize units rather than
2115   // HeapWordSize).
2116   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2117 
2118   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2119   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2120   size_t heap_alignment = collector_policy()->heap_alignment();
2121 
2122   // Ensure that the sizes are properly aligned.
2123   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2124   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2125   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2126 
2127   _refine_cte_cl = new RefineCardTableEntryClosure();
2128 
2129   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2130 
2131   // Reserve the maximum.
2132 
2133   // When compressed oops are enabled, the preferred heap base
2134   // is calculated by subtracting the requested size from the
2135   // 32Gb boundary and using the result as the base address for
2136   // heap reservation. If the requested size is not aligned to
2137   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2138   // into the ReservedHeapSpace constructor) then the actual
2139   // base of the reserved heap may end up differing from the
2140   // address that was requested (i.e. the preferred heap base).
2141   // If this happens then we could end up using a non-optimal
2142   // compressed oops mode.
2143 
2144   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2145                                                  heap_alignment);
2146 
2147   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2148 
2149   // Create the barrier set for the entire reserved region.
2150   G1SATBCardTableLoggingModRefBS* bs
2151     = new G1SATBCardTableLoggingModRefBS(reserved_region());
2152   bs->initialize();
2153   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2154   set_barrier_set(bs);
2155 
2156   // Also create a G1 rem set.
2157   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2158 
2159   // Carve out the G1 part of the heap.
2160 
2161   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2162   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2163   G1RegionToSpaceMapper* heap_storage =
2164     G1RegionToSpaceMapper::create_mapper(g1_rs,
2165                                          g1_rs.size(),
2166                                          page_size,
2167                                          HeapRegion::GrainBytes,
2168                                          1,
2169                                          mtJavaHeap);
2170   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2171                        max_byte_size, page_size,
2172                        heap_rs.base(),
2173                        heap_rs.size());
2174   heap_storage->set_mapping_changed_listener(&_listener);
2175 
2176   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2177   G1RegionToSpaceMapper* bot_storage =
2178     create_aux_memory_mapper("Block offset table",
2179                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2180                              G1BlockOffsetSharedArray::heap_map_factor());
2181 
2182   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2183   G1RegionToSpaceMapper* cardtable_storage =
2184     create_aux_memory_mapper("Card table",
2185                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2186                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
2187 
2188   G1RegionToSpaceMapper* card_counts_storage =
2189     create_aux_memory_mapper("Card counts table",
2190                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2191                              G1CardCounts::heap_map_factor());
2192 
2193   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2194   G1RegionToSpaceMapper* prev_bitmap_storage =
2195     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2196   G1RegionToSpaceMapper* next_bitmap_storage =
2197     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2198 
2199   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2200   g1_barrier_set()->initialize(cardtable_storage);
2201    // Do later initialization work for concurrent refinement.
2202   _cg1r->init(card_counts_storage);
2203 
2204   // 6843694 - ensure that the maximum region index can fit
2205   // in the remembered set structures.
2206   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2207   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2208 
2209   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2210   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2211   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2212             "too many cards per region");
2213 
2214   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2215 
2216   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2217 
2218   {
2219     HeapWord* start = _hrm.reserved().start();
2220     HeapWord* end = _hrm.reserved().end();
2221     size_t granularity = HeapRegion::GrainBytes;
2222 
2223     _in_cset_fast_test.initialize(start, end, granularity);
2224     _humongous_reclaim_candidates.initialize(start, end, granularity);
2225   }
2226 
2227   // Create the ConcurrentMark data structure and thread.
2228   // (Must do this late, so that "max_regions" is defined.)
2229   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2230   if (_cm == NULL || !_cm->completed_initialization()) {
2231     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2232     return JNI_ENOMEM;
2233   }
2234   _cmThread = _cm->cmThread();
2235 
2236   // Initialize the from_card cache structure of HeapRegionRemSet.
2237   HeapRegionRemSet::init_heap(max_regions());
2238 
2239   // Now expand into the initial heap size.
2240   if (!expand(init_byte_size)) {
2241     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2242     return JNI_ENOMEM;
2243   }
2244 
2245   // Perform any initialization actions delegated to the policy.
2246   g1_policy()->init();
2247 
2248   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2249                                                SATB_Q_FL_lock,
2250                                                G1SATBProcessCompletedThreshold,
2251                                                Shared_SATB_Q_lock);
2252 
2253   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2254                                                 DirtyCardQ_CBL_mon,
2255                                                 DirtyCardQ_FL_lock,
2256                                                 concurrent_g1_refine()->yellow_zone(),
2257                                                 concurrent_g1_refine()->red_zone(),
2258                                                 Shared_DirtyCardQ_lock);
2259 
2260   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2261                                     DirtyCardQ_CBL_mon,
2262                                     DirtyCardQ_FL_lock,
2263                                     -1, // never trigger processing
2264                                     -1, // no limit on length
2265                                     Shared_DirtyCardQ_lock,
2266                                     &JavaThread::dirty_card_queue_set());
2267 
2268   // Initialize the card queue set used to hold cards containing
2269   // references into the collection set.
2270   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2271                                              DirtyCardQ_CBL_mon,
2272                                              DirtyCardQ_FL_lock,
2273                                              -1, // never trigger processing
2274                                              -1, // no limit on length
2275                                              Shared_DirtyCardQ_lock,
2276                                              &JavaThread::dirty_card_queue_set());
2277 
2278   // Here we allocate the dummy HeapRegion that is required by the
2279   // G1AllocRegion class.
2280   HeapRegion* dummy_region = _hrm.get_dummy_region();
2281 
2282   // We'll re-use the same region whether the alloc region will
2283   // require BOT updates or not and, if it doesn't, then a non-young
2284   // region will complain that it cannot support allocations without
2285   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2286   dummy_region->set_eden();
2287   // Make sure it's full.
2288   dummy_region->set_top(dummy_region->end());
2289   G1AllocRegion::setup(this, dummy_region);
2290 
2291   _allocator->init_mutator_alloc_region();
2292 
2293   // Do create of the monitoring and management support so that
2294   // values in the heap have been properly initialized.
2295   _g1mm = new G1MonitoringSupport(this);
2296 
2297   G1StringDedup::initialize();
2298 
2299   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2300   for (uint i = 0; i < ParallelGCThreads; i++) {
2301     new (&_preserved_objs[i]) OopAndMarkOopStack();
2302   }
2303 
2304   return JNI_OK;
2305 }
2306 
2307 void G1CollectedHeap::stop() {
2308   // Stop all concurrent threads. We do this to make sure these threads
2309   // do not continue to execute and access resources (e.g. gclog_or_tty)
2310   // that are destroyed during shutdown.
2311   _cg1r->stop();
2312   _cmThread->stop();
2313   if (G1StringDedup::is_enabled()) {
2314     G1StringDedup::stop();
2315   }
2316 }
2317 
2318 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2319   return HeapRegion::max_region_size();
2320 }
2321 
2322 void G1CollectedHeap::post_initialize() {
2323   CollectedHeap::post_initialize();
2324   ref_processing_init();
2325 }
2326 
2327 void G1CollectedHeap::ref_processing_init() {
2328   // Reference processing in G1 currently works as follows:
2329   //
2330   // * There are two reference processor instances. One is
2331   //   used to record and process discovered references
2332   //   during concurrent marking; the other is used to
2333   //   record and process references during STW pauses
2334   //   (both full and incremental).
2335   // * Both ref processors need to 'span' the entire heap as
2336   //   the regions in the collection set may be dotted around.
2337   //
2338   // * For the concurrent marking ref processor:
2339   //   * Reference discovery is enabled at initial marking.
2340   //   * Reference discovery is disabled and the discovered
2341   //     references processed etc during remarking.
2342   //   * Reference discovery is MT (see below).
2343   //   * Reference discovery requires a barrier (see below).
2344   //   * Reference processing may or may not be MT
2345   //     (depending on the value of ParallelRefProcEnabled
2346   //     and ParallelGCThreads).
2347   //   * A full GC disables reference discovery by the CM
2348   //     ref processor and abandons any entries on it's
2349   //     discovered lists.
2350   //
2351   // * For the STW processor:
2352   //   * Non MT discovery is enabled at the start of a full GC.
2353   //   * Processing and enqueueing during a full GC is non-MT.
2354   //   * During a full GC, references are processed after marking.
2355   //
2356   //   * Discovery (may or may not be MT) is enabled at the start
2357   //     of an incremental evacuation pause.
2358   //   * References are processed near the end of a STW evacuation pause.
2359   //   * For both types of GC:
2360   //     * Discovery is atomic - i.e. not concurrent.
2361   //     * Reference discovery will not need a barrier.
2362 
2363   MemRegion mr = reserved_region();
2364 
2365   // Concurrent Mark ref processor
2366   _ref_processor_cm =
2367     new ReferenceProcessor(mr,    // span
2368                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2369                                 // mt processing
2370                            ParallelGCThreads,
2371                                 // degree of mt processing
2372                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2373                                 // mt discovery
2374                            MAX2(ParallelGCThreads, ConcGCThreads),
2375                                 // degree of mt discovery
2376                            false,
2377                                 // Reference discovery is not atomic
2378                            &_is_alive_closure_cm);
2379                                 // is alive closure
2380                                 // (for efficiency/performance)
2381 
2382   // STW ref processor
2383   _ref_processor_stw =
2384     new ReferenceProcessor(mr,    // span
2385                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2386                                 // mt processing
2387                            ParallelGCThreads,
2388                                 // degree of mt processing
2389                            (ParallelGCThreads > 1),
2390                                 // mt discovery
2391                            ParallelGCThreads,
2392                                 // degree of mt discovery
2393                            true,
2394                                 // Reference discovery is atomic
2395                            &_is_alive_closure_stw);
2396                                 // is alive closure
2397                                 // (for efficiency/performance)
2398 }
2399 
2400 size_t G1CollectedHeap::capacity() const {
2401   return _hrm.length() * HeapRegion::GrainBytes;
2402 }
2403 
2404 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2405   assert(!hr->is_continues_humongous(), "pre-condition");
2406   hr->reset_gc_time_stamp();
2407   if (hr->is_starts_humongous()) {
2408     uint first_index = hr->hrm_index() + 1;
2409     uint last_index = hr->last_hc_index();
2410     for (uint i = first_index; i < last_index; i += 1) {
2411       HeapRegion* chr = region_at(i);
2412       assert(chr->is_continues_humongous(), "sanity");
2413       chr->reset_gc_time_stamp();
2414     }
2415   }
2416 }
2417 
2418 #ifndef PRODUCT
2419 
2420 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2421 private:
2422   unsigned _gc_time_stamp;
2423   bool _failures;
2424 
2425 public:
2426   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2427     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2428 
2429   virtual bool doHeapRegion(HeapRegion* hr) {
2430     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2431     if (_gc_time_stamp != region_gc_time_stamp) {
2432       gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2433                              "expected %d", HR_FORMAT_PARAMS(hr),
2434                              region_gc_time_stamp, _gc_time_stamp);
2435       _failures = true;
2436     }
2437     return false;
2438   }
2439 
2440   bool failures() { return _failures; }
2441 };
2442 
2443 void G1CollectedHeap::check_gc_time_stamps() {
2444   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2445   heap_region_iterate(&cl);
2446   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2447 }
2448 #endif // PRODUCT
2449 
2450 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2451                                                  DirtyCardQueue* into_cset_dcq,
2452                                                  bool concurrent,
2453                                                  uint worker_i) {
2454   // Clean cards in the hot card cache
2455   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2456   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2457 
2458   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2459   size_t n_completed_buffers = 0;
2460   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2461     n_completed_buffers++;
2462   }
2463   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2464   dcqs.clear_n_completed_buffers();
2465   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2466 }
2467 
2468 // Computes the sum of the storage used by the various regions.
2469 size_t G1CollectedHeap::used() const {
2470   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2471   if (_archive_allocator != NULL) {
2472     result += _archive_allocator->used();
2473   }
2474   return result;
2475 }
2476 
2477 size_t G1CollectedHeap::used_unlocked() const {
2478   return _summary_bytes_used;
2479 }
2480 
2481 class SumUsedClosure: public HeapRegionClosure {
2482   size_t _used;
2483 public:
2484   SumUsedClosure() : _used(0) {}
2485   bool doHeapRegion(HeapRegion* r) {
2486     if (!r->is_continues_humongous()) {
2487       _used += r->used();
2488     }
2489     return false;
2490   }
2491   size_t result() { return _used; }
2492 };
2493 
2494 size_t G1CollectedHeap::recalculate_used() const {
2495   double recalculate_used_start = os::elapsedTime();
2496 
2497   SumUsedClosure blk;
2498   heap_region_iterate(&blk);
2499 
2500   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2501   return blk.result();
2502 }
2503 
2504 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2505   switch (cause) {
2506     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2507     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2508     case GCCause::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2509     case GCCause::_g1_humongous_allocation: return true;
2510     case GCCause::_update_allocation_context_stats_inc: return true;
2511     case GCCause::_wb_conc_mark:            return true;
2512     default:                                return false;
2513   }
2514 }
2515 
2516 #ifndef PRODUCT
2517 void G1CollectedHeap::allocate_dummy_regions() {
2518   // Let's fill up most of the region
2519   size_t word_size = HeapRegion::GrainWords - 1024;
2520   // And as a result the region we'll allocate will be humongous.
2521   guarantee(is_humongous(word_size), "sanity");
2522 
2523   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2524     // Let's use the existing mechanism for the allocation
2525     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2526                                                  AllocationContext::system());
2527     if (dummy_obj != NULL) {
2528       MemRegion mr(dummy_obj, word_size);
2529       CollectedHeap::fill_with_object(mr);
2530     } else {
2531       // If we can't allocate once, we probably cannot allocate
2532       // again. Let's get out of the loop.
2533       break;
2534     }
2535   }
2536 }
2537 #endif // !PRODUCT
2538 
2539 void G1CollectedHeap::increment_old_marking_cycles_started() {
2540   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2541     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2542     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2543     _old_marking_cycles_started, _old_marking_cycles_completed));
2544 
2545   _old_marking_cycles_started++;
2546 }
2547 
2548 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2549   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2550 
2551   // We assume that if concurrent == true, then the caller is a
2552   // concurrent thread that was joined the Suspendible Thread
2553   // Set. If there's ever a cheap way to check this, we should add an
2554   // assert here.
2555 
2556   // Given that this method is called at the end of a Full GC or of a
2557   // concurrent cycle, and those can be nested (i.e., a Full GC can
2558   // interrupt a concurrent cycle), the number of full collections
2559   // completed should be either one (in the case where there was no
2560   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2561   // behind the number of full collections started.
2562 
2563   // This is the case for the inner caller, i.e. a Full GC.
2564   assert(concurrent ||
2565          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2566          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2567          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2568                  "is inconsistent with _old_marking_cycles_completed = %u",
2569                  _old_marking_cycles_started, _old_marking_cycles_completed));
2570 
2571   // This is the case for the outer caller, i.e. the concurrent cycle.
2572   assert(!concurrent ||
2573          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2574          err_msg("for outer caller (concurrent cycle): "
2575                  "_old_marking_cycles_started = %u "
2576                  "is inconsistent with _old_marking_cycles_completed = %u",
2577                  _old_marking_cycles_started, _old_marking_cycles_completed));
2578 
2579   _old_marking_cycles_completed += 1;
2580 
2581   // We need to clear the "in_progress" flag in the CM thread before
2582   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2583   // is set) so that if a waiter requests another System.gc() it doesn't
2584   // incorrectly see that a marking cycle is still in progress.
2585   if (concurrent) {
2586     _cmThread->set_idle();
2587   }
2588 
2589   // This notify_all() will ensure that a thread that called
2590   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2591   // and it's waiting for a full GC to finish will be woken up. It is
2592   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2593   FullGCCount_lock->notify_all();
2594 }
2595 
2596 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2597   collector_state()->set_concurrent_cycle_started(true);
2598   _gc_timer_cm->register_gc_start(start_time);
2599 
2600   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2601   trace_heap_before_gc(_gc_tracer_cm);
2602 }
2603 
2604 void G1CollectedHeap::register_concurrent_cycle_end() {
2605   if (collector_state()->concurrent_cycle_started()) {
2606     if (_cm->has_aborted()) {
2607       _gc_tracer_cm->report_concurrent_mode_failure();
2608     }
2609 
2610     _gc_timer_cm->register_gc_end();
2611     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2612 
2613     // Clear state variables to prepare for the next concurrent cycle.
2614      collector_state()->set_concurrent_cycle_started(false);
2615     _heap_summary_sent = false;
2616   }
2617 }
2618 
2619 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2620   if (collector_state()->concurrent_cycle_started()) {
2621     // This function can be called when:
2622     //  the cleanup pause is run
2623     //  the concurrent cycle is aborted before the cleanup pause.
2624     //  the concurrent cycle is aborted after the cleanup pause,
2625     //   but before the concurrent cycle end has been registered.
2626     // Make sure that we only send the heap information once.
2627     if (!_heap_summary_sent) {
2628       trace_heap_after_gc(_gc_tracer_cm);
2629       _heap_summary_sent = true;
2630     }
2631   }
2632 }
2633 
2634 void G1CollectedHeap::collect(GCCause::Cause cause) {
2635   assert_heap_not_locked();
2636 
2637   uint gc_count_before;
2638   uint old_marking_count_before;
2639   uint full_gc_count_before;
2640   bool retry_gc;
2641 
2642   do {
2643     retry_gc = false;
2644 
2645     {
2646       MutexLocker ml(Heap_lock);
2647 
2648       // Read the GC count while holding the Heap_lock
2649       gc_count_before = total_collections();
2650       full_gc_count_before = total_full_collections();
2651       old_marking_count_before = _old_marking_cycles_started;
2652     }
2653 
2654     if (should_do_concurrent_full_gc(cause)) {
2655       // Schedule an initial-mark evacuation pause that will start a
2656       // concurrent cycle. We're setting word_size to 0 which means that
2657       // we are not requesting a post-GC allocation.
2658       VM_G1IncCollectionPause op(gc_count_before,
2659                                  0,     /* word_size */
2660                                  true,  /* should_initiate_conc_mark */
2661                                  g1_policy()->max_pause_time_ms(),
2662                                  cause);
2663       op.set_allocation_context(AllocationContext::current());
2664 
2665       VMThread::execute(&op);
2666       if (!op.pause_succeeded()) {
2667         if (old_marking_count_before == _old_marking_cycles_started) {
2668           retry_gc = op.should_retry_gc();
2669         } else {
2670           // A Full GC happened while we were trying to schedule the
2671           // initial-mark GC. No point in starting a new cycle given
2672           // that the whole heap was collected anyway.
2673         }
2674 
2675         if (retry_gc) {
2676           if (GC_locker::is_active_and_needs_gc()) {
2677             GC_locker::stall_until_clear();
2678           }
2679         }
2680       }
2681     } else {
2682       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2683           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2684 
2685         // Schedule a standard evacuation pause. We're setting word_size
2686         // to 0 which means that we are not requesting a post-GC allocation.
2687         VM_G1IncCollectionPause op(gc_count_before,
2688                                    0,     /* word_size */
2689                                    false, /* should_initiate_conc_mark */
2690                                    g1_policy()->max_pause_time_ms(),
2691                                    cause);
2692         VMThread::execute(&op);
2693       } else {
2694         // Schedule a Full GC.
2695         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2696         VMThread::execute(&op);
2697       }
2698     }
2699   } while (retry_gc);
2700 }
2701 
2702 bool G1CollectedHeap::is_in(const void* p) const {
2703   if (_hrm.reserved().contains(p)) {
2704     // Given that we know that p is in the reserved space,
2705     // heap_region_containing_raw() should successfully
2706     // return the containing region.
2707     HeapRegion* hr = heap_region_containing_raw(p);
2708     return hr->is_in(p);
2709   } else {
2710     return false;
2711   }
2712 }
2713 
2714 #ifdef ASSERT
2715 bool G1CollectedHeap::is_in_exact(const void* p) const {
2716   bool contains = reserved_region().contains(p);
2717   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2718   if (contains && available) {
2719     return true;
2720   } else {
2721     return false;
2722   }
2723 }
2724 #endif
2725 
2726 bool G1CollectedHeap::obj_in_cs(oop obj) {
2727   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2728   return r != NULL && r->in_collection_set();
2729 }
2730 
2731 // Iteration functions.
2732 
2733 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2734 
2735 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2736   ExtendedOopClosure* _cl;
2737 public:
2738   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2739   bool doHeapRegion(HeapRegion* r) {
2740     if (!r->is_continues_humongous()) {
2741       r->oop_iterate(_cl);
2742     }
2743     return false;
2744   }
2745 };
2746 
2747 // Iterates an ObjectClosure over all objects within a HeapRegion.
2748 
2749 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2750   ObjectClosure* _cl;
2751 public:
2752   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2753   bool doHeapRegion(HeapRegion* r) {
2754     if (!r->is_continues_humongous()) {
2755       r->object_iterate(_cl);
2756     }
2757     return false;
2758   }
2759 };
2760 
2761 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2762   IterateObjectClosureRegionClosure blk(cl);
2763   heap_region_iterate(&blk);
2764 }
2765 
2766 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2767   _hrm.iterate(cl);
2768 }
2769 
2770 void
2771 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2772                                          uint worker_id,
2773                                          HeapRegionClaimer *hrclaimer,
2774                                          bool concurrent) const {
2775   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2776 }
2777 
2778 // Clear the cached CSet starting regions and (more importantly)
2779 // the time stamps. Called when we reset the GC time stamp.
2780 void G1CollectedHeap::clear_cset_start_regions() {
2781   assert(_worker_cset_start_region != NULL, "sanity");
2782   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2783 
2784   for (uint i = 0; i < ParallelGCThreads; i++) {
2785     _worker_cset_start_region[i] = NULL;
2786     _worker_cset_start_region_time_stamp[i] = 0;
2787   }
2788 }
2789 
2790 // Given the id of a worker, obtain or calculate a suitable
2791 // starting region for iterating over the current collection set.
2792 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2793   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2794 
2795   HeapRegion* result = NULL;
2796   unsigned gc_time_stamp = get_gc_time_stamp();
2797 
2798   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2799     // Cached starting region for current worker was set
2800     // during the current pause - so it's valid.
2801     // Note: the cached starting heap region may be NULL
2802     // (when the collection set is empty).
2803     result = _worker_cset_start_region[worker_i];
2804     assert(result == NULL || result->in_collection_set(), "sanity");
2805     return result;
2806   }
2807 
2808   // The cached entry was not valid so let's calculate
2809   // a suitable starting heap region for this worker.
2810 
2811   // We want the parallel threads to start their collection
2812   // set iteration at different collection set regions to
2813   // avoid contention.
2814   // If we have:
2815   //          n collection set regions
2816   //          p threads
2817   // Then thread t will start at region floor ((t * n) / p)
2818 
2819   result = g1_policy()->collection_set();
2820   uint cs_size = g1_policy()->cset_region_length();
2821   uint active_workers = workers()->active_workers();
2822 
2823   uint end_ind   = (cs_size * worker_i) / active_workers;
2824   uint start_ind = 0;
2825 
2826   if (worker_i > 0 &&
2827       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2828     // Previous workers starting region is valid
2829     // so let's iterate from there
2830     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2831     result = _worker_cset_start_region[worker_i - 1];
2832   }
2833 
2834   for (uint i = start_ind; i < end_ind; i++) {
2835     result = result->next_in_collection_set();
2836   }
2837 
2838   // Note: the calculated starting heap region may be NULL
2839   // (when the collection set is empty).
2840   assert(result == NULL || result->in_collection_set(), "sanity");
2841   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2842          "should be updated only once per pause");
2843   _worker_cset_start_region[worker_i] = result;
2844   OrderAccess::storestore();
2845   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2846   return result;
2847 }
2848 
2849 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2850   HeapRegion* r = g1_policy()->collection_set();
2851   while (r != NULL) {
2852     HeapRegion* next = r->next_in_collection_set();
2853     if (cl->doHeapRegion(r)) {
2854       cl->incomplete();
2855       return;
2856     }
2857     r = next;
2858   }
2859 }
2860 
2861 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2862                                                   HeapRegionClosure *cl) {
2863   if (r == NULL) {
2864     // The CSet is empty so there's nothing to do.
2865     return;
2866   }
2867 
2868   assert(r->in_collection_set(),
2869          "Start region must be a member of the collection set.");
2870   HeapRegion* cur = r;
2871   while (cur != NULL) {
2872     HeapRegion* next = cur->next_in_collection_set();
2873     if (cl->doHeapRegion(cur) && false) {
2874       cl->incomplete();
2875       return;
2876     }
2877     cur = next;
2878   }
2879   cur = g1_policy()->collection_set();
2880   while (cur != r) {
2881     HeapRegion* next = cur->next_in_collection_set();
2882     if (cl->doHeapRegion(cur) && false) {
2883       cl->incomplete();
2884       return;
2885     }
2886     cur = next;
2887   }
2888 }
2889 
2890 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2891   HeapRegion* result = _hrm.next_region_in_heap(from);
2892   while (result != NULL && result->is_pinned()) {
2893     result = _hrm.next_region_in_heap(result);
2894   }
2895   return result;
2896 }
2897 
2898 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2899   HeapRegion* hr = heap_region_containing(addr);
2900   return hr->block_start(addr);
2901 }
2902 
2903 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2904   HeapRegion* hr = heap_region_containing(addr);
2905   return hr->block_size(addr);
2906 }
2907 
2908 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2909   HeapRegion* hr = heap_region_containing(addr);
2910   return hr->block_is_obj(addr);
2911 }
2912 
2913 bool G1CollectedHeap::supports_tlab_allocation() const {
2914   return true;
2915 }
2916 
2917 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2918   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2919 }
2920 
2921 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2922   return young_list()->eden_used_bytes();
2923 }
2924 
2925 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2926 // must be smaller than the humongous object limit.
2927 size_t G1CollectedHeap::max_tlab_size() const {
2928   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2929 }
2930 
2931 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2932   AllocationContext_t context = AllocationContext::current();
2933   return _allocator->unsafe_max_tlab_alloc(context);
2934 }
2935 
2936 size_t G1CollectedHeap::max_capacity() const {
2937   return _hrm.reserved().byte_size();
2938 }
2939 
2940 jlong G1CollectedHeap::millis_since_last_gc() {
2941   // assert(false, "NYI");
2942   return 0;
2943 }
2944 
2945 void G1CollectedHeap::prepare_for_verify() {
2946   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2947     ensure_parsability(false);
2948   }
2949   g1_rem_set()->prepare_for_verify();
2950 }
2951 
2952 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2953                                               VerifyOption vo) {
2954   switch (vo) {
2955   case VerifyOption_G1UsePrevMarking:
2956     return hr->obj_allocated_since_prev_marking(obj);
2957   case VerifyOption_G1UseNextMarking:
2958     return hr->obj_allocated_since_next_marking(obj);
2959   case VerifyOption_G1UseMarkWord:
2960     return false;
2961   default:
2962     ShouldNotReachHere();
2963   }
2964   return false; // keep some compilers happy
2965 }
2966 
2967 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2968   switch (vo) {
2969   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2970   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2971   case VerifyOption_G1UseMarkWord:    return NULL;
2972   default:                            ShouldNotReachHere();
2973   }
2974   return NULL; // keep some compilers happy
2975 }
2976 
2977 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2978   switch (vo) {
2979   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2980   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2981   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2982   default:                            ShouldNotReachHere();
2983   }
2984   return false; // keep some compilers happy
2985 }
2986 
2987 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2988   switch (vo) {
2989   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2990   case VerifyOption_G1UseNextMarking: return "NTAMS";
2991   case VerifyOption_G1UseMarkWord:    return "NONE";
2992   default:                            ShouldNotReachHere();
2993   }
2994   return NULL; // keep some compilers happy
2995 }
2996 
2997 class VerifyRootsClosure: public OopClosure {
2998 private:
2999   G1CollectedHeap* _g1h;
3000   VerifyOption     _vo;
3001   bool             _failures;
3002 public:
3003   // _vo == UsePrevMarking -> use "prev" marking information,
3004   // _vo == UseNextMarking -> use "next" marking information,
3005   // _vo == UseMarkWord    -> use mark word from object header.
3006   VerifyRootsClosure(VerifyOption vo) :
3007     _g1h(G1CollectedHeap::heap()),
3008     _vo(vo),
3009     _failures(false) { }
3010 
3011   bool failures() { return _failures; }
3012 
3013   template <class T> void do_oop_nv(T* p) {
3014     T heap_oop = oopDesc::load_heap_oop(p);
3015     if (!oopDesc::is_null(heap_oop)) {
3016       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3017       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3018         gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3019                                "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3020         if (_vo == VerifyOption_G1UseMarkWord) {
3021           gclog_or_tty->print_cr("  Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3022         }
3023         obj->print_on(gclog_or_tty);
3024         _failures = true;
3025       }
3026     }
3027   }
3028 
3029   void do_oop(oop* p)       { do_oop_nv(p); }
3030   void do_oop(narrowOop* p) { do_oop_nv(p); }
3031 };
3032 
3033 class G1VerifyCodeRootOopClosure: public OopClosure {
3034   G1CollectedHeap* _g1h;
3035   OopClosure* _root_cl;
3036   nmethod* _nm;
3037   VerifyOption _vo;
3038   bool _failures;
3039 
3040   template <class T> void do_oop_work(T* p) {
3041     // First verify that this root is live
3042     _root_cl->do_oop(p);
3043 
3044     if (!G1VerifyHeapRegionCodeRoots) {
3045       // We're not verifying the code roots attached to heap region.
3046       return;
3047     }
3048 
3049     // Don't check the code roots during marking verification in a full GC
3050     if (_vo == VerifyOption_G1UseMarkWord) {
3051       return;
3052     }
3053 
3054     // Now verify that the current nmethod (which contains p) is
3055     // in the code root list of the heap region containing the
3056     // object referenced by p.
3057 
3058     T heap_oop = oopDesc::load_heap_oop(p);
3059     if (!oopDesc::is_null(heap_oop)) {
3060       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3061 
3062       // Now fetch the region containing the object
3063       HeapRegion* hr = _g1h->heap_region_containing(obj);
3064       HeapRegionRemSet* hrrs = hr->rem_set();
3065       // Verify that the strong code root list for this region
3066       // contains the nmethod
3067       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3068         gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3069                                "from nmethod " PTR_FORMAT " not in strong "
3070                                "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3071                                p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3072         _failures = true;
3073       }
3074     }
3075   }
3076 
3077 public:
3078   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3079     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3080 
3081   void do_oop(oop* p) { do_oop_work(p); }
3082   void do_oop(narrowOop* p) { do_oop_work(p); }
3083 
3084   void set_nmethod(nmethod* nm) { _nm = nm; }
3085   bool failures() { return _failures; }
3086 };
3087 
3088 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3089   G1VerifyCodeRootOopClosure* _oop_cl;
3090 
3091 public:
3092   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3093     _oop_cl(oop_cl) {}
3094 
3095   void do_code_blob(CodeBlob* cb) {
3096     nmethod* nm = cb->as_nmethod_or_null();
3097     if (nm != NULL) {
3098       _oop_cl->set_nmethod(nm);
3099       nm->oops_do(_oop_cl);
3100     }
3101   }
3102 };
3103 
3104 class YoungRefCounterClosure : public OopClosure {
3105   G1CollectedHeap* _g1h;
3106   int              _count;
3107  public:
3108   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3109   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3110   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3111 
3112   int count() { return _count; }
3113   void reset_count() { _count = 0; };
3114 };
3115 
3116 class VerifyKlassClosure: public KlassClosure {
3117   YoungRefCounterClosure _young_ref_counter_closure;
3118   OopClosure *_oop_closure;
3119  public:
3120   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3121   void do_klass(Klass* k) {
3122     k->oops_do(_oop_closure);
3123 
3124     _young_ref_counter_closure.reset_count();
3125     k->oops_do(&_young_ref_counter_closure);
3126     if (_young_ref_counter_closure.count() > 0) {
3127       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3128     }
3129   }
3130 };
3131 
3132 class VerifyLivenessOopClosure: public OopClosure {
3133   G1CollectedHeap* _g1h;
3134   VerifyOption _vo;
3135 public:
3136   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3137     _g1h(g1h), _vo(vo)
3138   { }
3139   void do_oop(narrowOop *p) { do_oop_work(p); }
3140   void do_oop(      oop *p) { do_oop_work(p); }
3141 
3142   template <class T> void do_oop_work(T *p) {
3143     oop obj = oopDesc::load_decode_heap_oop(p);
3144     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3145               "Dead object referenced by a not dead object");
3146   }
3147 };
3148 
3149 class VerifyObjsInRegionClosure: public ObjectClosure {
3150 private:
3151   G1CollectedHeap* _g1h;
3152   size_t _live_bytes;
3153   HeapRegion *_hr;
3154   VerifyOption _vo;
3155 public:
3156   // _vo == UsePrevMarking -> use "prev" marking information,
3157   // _vo == UseNextMarking -> use "next" marking information,
3158   // _vo == UseMarkWord    -> use mark word from object header.
3159   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3160     : _live_bytes(0), _hr(hr), _vo(vo) {
3161     _g1h = G1CollectedHeap::heap();
3162   }
3163   void do_object(oop o) {
3164     VerifyLivenessOopClosure isLive(_g1h, _vo);
3165     assert(o != NULL, "Huh?");
3166     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3167       // If the object is alive according to the mark word,
3168       // then verify that the marking information agrees.
3169       // Note we can't verify the contra-positive of the
3170       // above: if the object is dead (according to the mark
3171       // word), it may not be marked, or may have been marked
3172       // but has since became dead, or may have been allocated
3173       // since the last marking.
3174       if (_vo == VerifyOption_G1UseMarkWord) {
3175         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3176       }
3177 
3178       o->oop_iterate_no_header(&isLive);
3179       if (!_hr->obj_allocated_since_prev_marking(o)) {
3180         size_t obj_size = o->size();    // Make sure we don't overflow
3181         _live_bytes += (obj_size * HeapWordSize);
3182       }
3183     }
3184   }
3185   size_t live_bytes() { return _live_bytes; }
3186 };
3187 
3188 class VerifyArchiveOopClosure: public OopClosure {
3189 public:
3190   VerifyArchiveOopClosure(HeapRegion *hr) { }
3191   void do_oop(narrowOop *p) { do_oop_work(p); }
3192   void do_oop(      oop *p) { do_oop_work(p); }
3193 
3194   template <class T> void do_oop_work(T *p) {
3195     oop obj = oopDesc::load_decode_heap_oop(p);
3196     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3197               err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3198                       p2i(p), p2i(obj)));
3199   }
3200 };
3201 
3202 class VerifyArchiveRegionClosure: public ObjectClosure {
3203 public:
3204   VerifyArchiveRegionClosure(HeapRegion *hr) { }
3205   // Verify that all object pointers are to archive regions.
3206   void do_object(oop o) {
3207     VerifyArchiveOopClosure checkOop(NULL);
3208     assert(o != NULL, "Should not be here for NULL oops");
3209     o->oop_iterate_no_header(&checkOop);
3210   }
3211 };
3212 
3213 class VerifyRegionClosure: public HeapRegionClosure {
3214 private:
3215   bool             _par;
3216   VerifyOption     _vo;
3217   bool             _failures;
3218 public:
3219   // _vo == UsePrevMarking -> use "prev" marking information,
3220   // _vo == UseNextMarking -> use "next" marking information,
3221   // _vo == UseMarkWord    -> use mark word from object header.
3222   VerifyRegionClosure(bool par, VerifyOption vo)
3223     : _par(par),
3224       _vo(vo),
3225       _failures(false) {}
3226 
3227   bool failures() {
3228     return _failures;
3229   }
3230 
3231   bool doHeapRegion(HeapRegion* r) {
3232     // For archive regions, verify there are no heap pointers to
3233     // non-pinned regions. For all others, verify liveness info.
3234     if (r->is_archive()) {
3235       VerifyArchiveRegionClosure verify_oop_pointers(r);
3236       r->object_iterate(&verify_oop_pointers);
3237       return true;
3238     }
3239     if (!r->is_continues_humongous()) {
3240       bool failures = false;
3241       r->verify(_vo, &failures);
3242       if (failures) {
3243         _failures = true;
3244       } else {
3245         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3246         r->object_iterate(&not_dead_yet_cl);
3247         if (_vo != VerifyOption_G1UseNextMarking) {
3248           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3249             gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3250                                    "max_live_bytes " SIZE_FORMAT " "
3251                                    "< calculated " SIZE_FORMAT,
3252                                    p2i(r->bottom()), p2i(r->end()),
3253                                    r->max_live_bytes(),
3254                                  not_dead_yet_cl.live_bytes());
3255             _failures = true;
3256           }
3257         } else {
3258           // When vo == UseNextMarking we cannot currently do a sanity
3259           // check on the live bytes as the calculation has not been
3260           // finalized yet.
3261         }
3262       }
3263     }
3264     return false; // stop the region iteration if we hit a failure
3265   }
3266 };
3267 
3268 // This is the task used for parallel verification of the heap regions
3269 
3270 class G1ParVerifyTask: public AbstractGangTask {
3271 private:
3272   G1CollectedHeap*  _g1h;
3273   VerifyOption      _vo;
3274   bool              _failures;
3275   HeapRegionClaimer _hrclaimer;
3276 
3277 public:
3278   // _vo == UsePrevMarking -> use "prev" marking information,
3279   // _vo == UseNextMarking -> use "next" marking information,
3280   // _vo == UseMarkWord    -> use mark word from object header.
3281   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3282       AbstractGangTask("Parallel verify task"),
3283       _g1h(g1h),
3284       _vo(vo),
3285       _failures(false),
3286       _hrclaimer(g1h->workers()->active_workers()) {}
3287 
3288   bool failures() {
3289     return _failures;
3290   }
3291 
3292   void work(uint worker_id) {
3293     HandleMark hm;
3294     VerifyRegionClosure blk(true, _vo);
3295     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3296     if (blk.failures()) {
3297       _failures = true;
3298     }
3299   }
3300 };
3301 
3302 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3303   if (SafepointSynchronize::is_at_safepoint()) {
3304     assert(Thread::current()->is_VM_thread(),
3305            "Expected to be executed serially by the VM thread at this point");
3306 
3307     if (!silent) { gclog_or_tty->print("Roots "); }
3308     VerifyRootsClosure rootsCl(vo);
3309     VerifyKlassClosure klassCl(this, &rootsCl);
3310     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3311 
3312     // We apply the relevant closures to all the oops in the
3313     // system dictionary, class loader data graph, the string table
3314     // and the nmethods in the code cache.
3315     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3316     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3317 
3318     {
3319       G1RootProcessor root_processor(this, 1);
3320       root_processor.process_all_roots(&rootsCl,
3321                                        &cldCl,
3322                                        &blobsCl);
3323     }
3324 
3325     bool failures = rootsCl.failures() || codeRootsCl.failures();
3326 
3327     if (vo != VerifyOption_G1UseMarkWord) {
3328       // If we're verifying during a full GC then the region sets
3329       // will have been torn down at the start of the GC. Therefore
3330       // verifying the region sets will fail. So we only verify
3331       // the region sets when not in a full GC.
3332       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3333       verify_region_sets();
3334     }
3335 
3336     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3337     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3338 
3339       G1ParVerifyTask task(this, vo);
3340       workers()->run_task(&task);
3341       if (task.failures()) {
3342         failures = true;
3343       }
3344 
3345     } else {
3346       VerifyRegionClosure blk(false, vo);
3347       heap_region_iterate(&blk);
3348       if (blk.failures()) {
3349         failures = true;
3350       }
3351     }
3352 
3353     if (G1StringDedup::is_enabled()) {
3354       if (!silent) gclog_or_tty->print("StrDedup ");
3355       G1StringDedup::verify();
3356     }
3357 
3358     if (failures) {
3359       gclog_or_tty->print_cr("Heap:");
3360       // It helps to have the per-region information in the output to
3361       // help us track down what went wrong. This is why we call
3362       // print_extended_on() instead of print_on().
3363       print_extended_on(gclog_or_tty);
3364       gclog_or_tty->cr();
3365       gclog_or_tty->flush();
3366     }
3367     guarantee(!failures, "there should not have been any failures");
3368   } else {
3369     if (!silent) {
3370       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3371       if (G1StringDedup::is_enabled()) {
3372         gclog_or_tty->print(", StrDedup");
3373       }
3374       gclog_or_tty->print(") ");
3375     }
3376   }
3377 }
3378 
3379 void G1CollectedHeap::verify(bool silent) {
3380   verify(silent, VerifyOption_G1UsePrevMarking);
3381 }
3382 
3383 double G1CollectedHeap::verify(bool guard, const char* msg) {
3384   double verify_time_ms = 0.0;
3385 
3386   if (guard && total_collections() >= VerifyGCStartAt) {
3387     double verify_start = os::elapsedTime();
3388     HandleMark hm;  // Discard invalid handles created during verification
3389     prepare_for_verify();
3390     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3391     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3392   }
3393 
3394   return verify_time_ms;
3395 }
3396 
3397 void G1CollectedHeap::verify_before_gc() {
3398   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3399   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3400 }
3401 
3402 void G1CollectedHeap::verify_after_gc() {
3403   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3404   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3405 }
3406 
3407 class PrintRegionClosure: public HeapRegionClosure {
3408   outputStream* _st;
3409 public:
3410   PrintRegionClosure(outputStream* st) : _st(st) {}
3411   bool doHeapRegion(HeapRegion* r) {
3412     r->print_on(_st);
3413     return false;
3414   }
3415 };
3416 
3417 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3418                                        const HeapRegion* hr,
3419                                        const VerifyOption vo) const {
3420   switch (vo) {
3421   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3422   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3423   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3424   default:                            ShouldNotReachHere();
3425   }
3426   return false; // keep some compilers happy
3427 }
3428 
3429 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3430                                        const VerifyOption vo) const {
3431   switch (vo) {
3432   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3433   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3434   case VerifyOption_G1UseMarkWord: {
3435     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3436     return !obj->is_gc_marked() && !hr->is_archive();
3437   }
3438   default:                            ShouldNotReachHere();
3439   }
3440   return false; // keep some compilers happy
3441 }
3442 
3443 void G1CollectedHeap::print_on(outputStream* st) const {
3444   st->print(" %-20s", "garbage-first heap");
3445   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3446             capacity()/K, used_unlocked()/K);
3447   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3448             p2i(_hrm.reserved().start()),
3449             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3450             p2i(_hrm.reserved().end()));
3451   st->cr();
3452   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3453   uint young_regions = _young_list->length();
3454   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3455             (size_t) young_regions * HeapRegion::GrainBytes / K);
3456   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3457   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3458             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3459   st->cr();
3460   MetaspaceAux::print_on(st);
3461 }
3462 
3463 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3464   print_on(st);
3465 
3466   // Print the per-region information.
3467   st->cr();
3468   st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3469                "HS=humongous(starts), HC=humongous(continues), "
3470                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3471                "PTAMS=previous top-at-mark-start, "
3472                "NTAMS=next top-at-mark-start)");
3473   PrintRegionClosure blk(st);
3474   heap_region_iterate(&blk);
3475 }
3476 
3477 void G1CollectedHeap::print_on_error(outputStream* st) const {
3478   this->CollectedHeap::print_on_error(st);
3479 
3480   if (_cm != NULL) {
3481     st->cr();
3482     _cm->print_on_error(st);
3483   }
3484 }
3485 
3486 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3487   workers()->print_worker_threads_on(st);
3488   _cmThread->print_on(st);
3489   st->cr();
3490   _cm->print_worker_threads_on(st);
3491   _cg1r->print_worker_threads_on(st);
3492   if (G1StringDedup::is_enabled()) {
3493     G1StringDedup::print_worker_threads_on(st);
3494   }
3495 }
3496 
3497 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3498   workers()->threads_do(tc);
3499   tc->do_thread(_cmThread);
3500   _cg1r->threads_do(tc);
3501   if (G1StringDedup::is_enabled()) {
3502     G1StringDedup::threads_do(tc);
3503   }
3504 }
3505 
3506 void G1CollectedHeap::print_tracing_info() const {
3507   // We'll overload this to mean "trace GC pause statistics."
3508   if (TraceYoungGenTime || TraceOldGenTime) {
3509     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3510     // to that.
3511     g1_policy()->print_tracing_info();
3512   }
3513   if (G1SummarizeRSetStats) {
3514     g1_rem_set()->print_summary_info();
3515   }
3516   if (G1SummarizeConcMark) {
3517     concurrent_mark()->print_summary_info();
3518   }
3519   g1_policy()->print_yg_surv_rate_info();
3520 }
3521 
3522 #ifndef PRODUCT
3523 // Helpful for debugging RSet issues.
3524 
3525 class PrintRSetsClosure : public HeapRegionClosure {
3526 private:
3527   const char* _msg;
3528   size_t _occupied_sum;
3529 
3530 public:
3531   bool doHeapRegion(HeapRegion* r) {
3532     HeapRegionRemSet* hrrs = r->rem_set();
3533     size_t occupied = hrrs->occupied();
3534     _occupied_sum += occupied;
3535 
3536     gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3537                            HR_FORMAT_PARAMS(r));
3538     if (occupied == 0) {
3539       gclog_or_tty->print_cr("  RSet is empty");
3540     } else {
3541       hrrs->print();
3542     }
3543     gclog_or_tty->print_cr("----------");
3544     return false;
3545   }
3546 
3547   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3548     gclog_or_tty->cr();
3549     gclog_or_tty->print_cr("========================================");
3550     gclog_or_tty->print_cr("%s", msg);
3551     gclog_or_tty->cr();
3552   }
3553 
3554   ~PrintRSetsClosure() {
3555     gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3556     gclog_or_tty->print_cr("========================================");
3557     gclog_or_tty->cr();
3558   }
3559 };
3560 
3561 void G1CollectedHeap::print_cset_rsets() {
3562   PrintRSetsClosure cl("Printing CSet RSets");
3563   collection_set_iterate(&cl);
3564 }
3565 
3566 void G1CollectedHeap::print_all_rsets() {
3567   PrintRSetsClosure cl("Printing All RSets");;
3568   heap_region_iterate(&cl);
3569 }
3570 #endif // PRODUCT
3571 
3572 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3573   YoungList* young_list = heap()->young_list();
3574 
3575   size_t eden_used_bytes = young_list->eden_used_bytes();
3576   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3577 
3578   size_t eden_capacity_bytes =
3579     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3580 
3581   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3582   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3583 }
3584 
3585 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3586   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3587   gc_tracer->report_gc_heap_summary(when, heap_summary);
3588 
3589   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3590   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3591 }
3592 
3593 
3594 G1CollectedHeap* G1CollectedHeap::heap() {
3595   CollectedHeap* heap = Universe::heap();
3596   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3597   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3598   return (G1CollectedHeap*)heap;
3599 }
3600 
3601 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3602   // always_do_update_barrier = false;
3603   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3604   // Fill TLAB's and such
3605   accumulate_statistics_all_tlabs();
3606   ensure_parsability(true);
3607 
3608   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3609       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3610     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3611   }
3612 }
3613 
3614 void G1CollectedHeap::gc_epilogue(bool full) {
3615 
3616   if (G1SummarizeRSetStats &&
3617       (G1SummarizeRSetStatsPeriod > 0) &&
3618       // we are at the end of the GC. Total collections has already been increased.
3619       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3620     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3621   }
3622 
3623   // FIXME: what is this about?
3624   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3625   // is set.
3626   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3627                         "derived pointer present"));
3628   // always_do_update_barrier = true;
3629 
3630   resize_all_tlabs();
3631   allocation_context_stats().update(full);
3632 
3633   // We have just completed a GC. Update the soft reference
3634   // policy with the new heap occupancy
3635   Universe::update_heap_info_at_gc();
3636 }
3637 
3638 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3639                                                uint gc_count_before,
3640                                                bool* succeeded,
3641                                                GCCause::Cause gc_cause) {
3642   assert_heap_not_locked_and_not_at_safepoint();
3643   g1_policy()->record_stop_world_start();
3644   VM_G1IncCollectionPause op(gc_count_before,
3645                              word_size,
3646                              false, /* should_initiate_conc_mark */
3647                              g1_policy()->max_pause_time_ms(),
3648                              gc_cause);
3649 
3650   op.set_allocation_context(AllocationContext::current());
3651   VMThread::execute(&op);
3652 
3653   HeapWord* result = op.result();
3654   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3655   assert(result == NULL || ret_succeeded,
3656          "the result should be NULL if the VM did not succeed");
3657   *succeeded = ret_succeeded;
3658 
3659   assert_heap_not_locked();
3660   return result;
3661 }
3662 
3663 void
3664 G1CollectedHeap::doConcurrentMark() {
3665   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3666   if (!_cmThread->in_progress()) {
3667     _cmThread->set_started();
3668     CGC_lock->notify();
3669   }
3670 }
3671 
3672 size_t G1CollectedHeap::pending_card_num() {
3673   size_t extra_cards = 0;
3674   JavaThread *curr = Threads::first();
3675   while (curr != NULL) {
3676     DirtyCardQueue& dcq = curr->dirty_card_queue();
3677     extra_cards += dcq.size();
3678     curr = curr->next();
3679   }
3680   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3681   size_t buffer_size = dcqs.buffer_size();
3682   size_t buffer_num = dcqs.completed_buffers_num();
3683 
3684   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3685   // in bytes - not the number of 'entries'. We need to convert
3686   // into a number of cards.
3687   return (buffer_size * buffer_num + extra_cards) / oopSize;
3688 }
3689 
3690 size_t G1CollectedHeap::cards_scanned() {
3691   return g1_rem_set()->cardsScanned();
3692 }
3693 
3694 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3695  private:
3696   size_t _total_humongous;
3697   size_t _candidate_humongous;
3698 
3699   DirtyCardQueue _dcq;
3700 
3701   // We don't nominate objects with many remembered set entries, on
3702   // the assumption that such objects are likely still live.
3703   bool is_remset_small(HeapRegion* region) const {
3704     HeapRegionRemSet* const rset = region->rem_set();
3705     return G1EagerReclaimHumongousObjectsWithStaleRefs
3706       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3707       : rset->is_empty();
3708   }
3709 
3710   bool is_typeArray_region(HeapRegion* region) const {
3711     return oop(region->bottom())->is_typeArray();
3712   }
3713 
3714   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3715     assert(region->is_starts_humongous(), "Must start a humongous object");
3716 
3717     // Candidate selection must satisfy the following constraints
3718     // while concurrent marking is in progress:
3719     //
3720     // * In order to maintain SATB invariants, an object must not be
3721     // reclaimed if it was allocated before the start of marking and
3722     // has not had its references scanned.  Such an object must have
3723     // its references (including type metadata) scanned to ensure no
3724     // live objects are missed by the marking process.  Objects
3725     // allocated after the start of concurrent marking don't need to
3726     // be scanned.
3727     //
3728     // * An object must not be reclaimed if it is on the concurrent
3729     // mark stack.  Objects allocated after the start of concurrent
3730     // marking are never pushed on the mark stack.
3731     //
3732     // Nominating only objects allocated after the start of concurrent
3733     // marking is sufficient to meet both constraints.  This may miss
3734     // some objects that satisfy the constraints, but the marking data
3735     // structures don't support efficiently performing the needed
3736     // additional tests or scrubbing of the mark stack.
3737     //
3738     // However, we presently only nominate is_typeArray() objects.
3739     // A humongous object containing references induces remembered
3740     // set entries on other regions.  In order to reclaim such an
3741     // object, those remembered sets would need to be cleaned up.
3742     //
3743     // We also treat is_typeArray() objects specially, allowing them
3744     // to be reclaimed even if allocated before the start of
3745     // concurrent mark.  For this we rely on mark stack insertion to
3746     // exclude is_typeArray() objects, preventing reclaiming an object
3747     // that is in the mark stack.  We also rely on the metadata for
3748     // such objects to be built-in and so ensured to be kept live.
3749     // Frequent allocation and drop of large binary blobs is an
3750     // important use case for eager reclaim, and this special handling
3751     // may reduce needed headroom.
3752 
3753     return is_typeArray_region(region) && is_remset_small(region);
3754   }
3755 
3756  public:
3757   RegisterHumongousWithInCSetFastTestClosure()
3758   : _total_humongous(0),
3759     _candidate_humongous(0),
3760     _dcq(&JavaThread::dirty_card_queue_set()) {
3761   }
3762 
3763   virtual bool doHeapRegion(HeapRegion* r) {
3764     if (!r->is_starts_humongous()) {
3765       return false;
3766     }
3767     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3768 
3769     bool is_candidate = humongous_region_is_candidate(g1h, r);
3770     uint rindex = r->hrm_index();
3771     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3772     if (is_candidate) {
3773       _candidate_humongous++;
3774       g1h->register_humongous_region_with_cset(rindex);
3775       // Is_candidate already filters out humongous object with large remembered sets.
3776       // If we have a humongous object with a few remembered sets, we simply flush these
3777       // remembered set entries into the DCQS. That will result in automatic
3778       // re-evaluation of their remembered set entries during the following evacuation
3779       // phase.
3780       if (!r->rem_set()->is_empty()) {
3781         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3782                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3783         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3784         HeapRegionRemSetIterator hrrs(r->rem_set());
3785         size_t card_index;
3786         while (hrrs.has_next(card_index)) {
3787           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3788           // The remembered set might contain references to already freed
3789           // regions. Filter out such entries to avoid failing card table
3790           // verification.
3791           if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3792             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3793               *card_ptr = CardTableModRefBS::dirty_card_val();
3794               _dcq.enqueue(card_ptr);
3795             }
3796           }
3797         }
3798         r->rem_set()->clear_locked();
3799       }
3800       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3801     }
3802     _total_humongous++;
3803 
3804     return false;
3805   }
3806 
3807   size_t total_humongous() const { return _total_humongous; }
3808   size_t candidate_humongous() const { return _candidate_humongous; }
3809 
3810   void flush_rem_set_entries() { _dcq.flush(); }
3811 };
3812 
3813 void G1CollectedHeap::register_humongous_regions_with_cset() {
3814   if (!G1EagerReclaimHumongousObjects) {
3815     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3816     return;
3817   }
3818   double time = os::elapsed_counter();
3819 
3820   // Collect reclaim candidate information and register candidates with cset.
3821   RegisterHumongousWithInCSetFastTestClosure cl;
3822   heap_region_iterate(&cl);
3823 
3824   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3825   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3826                                                                   cl.total_humongous(),
3827                                                                   cl.candidate_humongous());
3828   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3829 
3830   // Finally flush all remembered set entries to re-check into the global DCQS.
3831   cl.flush_rem_set_entries();
3832 }
3833 
3834 void
3835 G1CollectedHeap::setup_surviving_young_words() {
3836   assert(_surviving_young_words == NULL, "pre-condition");
3837   uint array_length = g1_policy()->young_cset_region_length();
3838   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3839   if (_surviving_young_words == NULL) {
3840     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3841                           "Not enough space for young surv words summary.");
3842   }
3843   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3844 #ifdef ASSERT
3845   for (uint i = 0;  i < array_length; ++i) {
3846     assert( _surviving_young_words[i] == 0, "memset above" );
3847   }
3848 #endif // !ASSERT
3849 }
3850 
3851 void
3852 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3853   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3854   uint array_length = g1_policy()->young_cset_region_length();
3855   for (uint i = 0; i < array_length; ++i) {
3856     _surviving_young_words[i] += surv_young_words[i];
3857   }
3858 }
3859 
3860 void
3861 G1CollectedHeap::cleanup_surviving_young_words() {
3862   guarantee( _surviving_young_words != NULL, "pre-condition" );
3863   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3864   _surviving_young_words = NULL;
3865 }
3866 
3867 #ifdef ASSERT
3868 class VerifyCSetClosure: public HeapRegionClosure {
3869 public:
3870   bool doHeapRegion(HeapRegion* hr) {
3871     // Here we check that the CSet region's RSet is ready for parallel
3872     // iteration. The fields that we'll verify are only manipulated
3873     // when the region is part of a CSet and is collected. Afterwards,
3874     // we reset these fields when we clear the region's RSet (when the
3875     // region is freed) so they are ready when the region is
3876     // re-allocated. The only exception to this is if there's an
3877     // evacuation failure and instead of freeing the region we leave
3878     // it in the heap. In that case, we reset these fields during
3879     // evacuation failure handling.
3880     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3881 
3882     // Here's a good place to add any other checks we'd like to
3883     // perform on CSet regions.
3884     return false;
3885   }
3886 };
3887 #endif // ASSERT
3888 
3889 uint G1CollectedHeap::num_task_queues() const {
3890   return _task_queues->size();
3891 }
3892 
3893 #if TASKQUEUE_STATS
3894 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3895   st->print_raw_cr("GC Task Stats");
3896   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3897   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3898 }
3899 
3900 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3901   print_taskqueue_stats_hdr(st);
3902 
3903   TaskQueueStats totals;
3904   const uint n = num_task_queues();
3905   for (uint i = 0; i < n; ++i) {
3906     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3907     totals += task_queue(i)->stats;
3908   }
3909   st->print_raw("tot "); totals.print(st); st->cr();
3910 
3911   DEBUG_ONLY(totals.verify());
3912 }
3913 
3914 void G1CollectedHeap::reset_taskqueue_stats() {
3915   const uint n = num_task_queues();
3916   for (uint i = 0; i < n; ++i) {
3917     task_queue(i)->stats.reset();
3918   }
3919 }
3920 #endif // TASKQUEUE_STATS
3921 
3922 void G1CollectedHeap::log_gc_header() {
3923   if (!G1Log::fine()) {
3924     return;
3925   }
3926 
3927   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3928 
3929   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3930     .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3931     .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3932 
3933   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3934 }
3935 
3936 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3937   if (!G1Log::fine()) {
3938     return;
3939   }
3940 
3941   if (G1Log::finer()) {
3942     if (evacuation_failed()) {
3943       gclog_or_tty->print(" (to-space exhausted)");
3944     }
3945     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3946     g1_policy()->phase_times()->note_gc_end();
3947     g1_policy()->phase_times()->print(pause_time_sec);
3948     g1_policy()->print_detailed_heap_transition();
3949   } else {
3950     if (evacuation_failed()) {
3951       gclog_or_tty->print("--");
3952     }
3953     g1_policy()->print_heap_transition();
3954     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3955   }
3956   gclog_or_tty->flush();
3957 }
3958 
3959 void G1CollectedHeap::wait_for_root_region_scanning() {
3960   double scan_wait_start = os::elapsedTime();
3961   // We have to wait until the CM threads finish scanning the
3962   // root regions as it's the only way to ensure that all the
3963   // objects on them have been correctly scanned before we start
3964   // moving them during the GC.
3965   bool waited = _cm->root_regions()->wait_until_scan_finished();
3966   double wait_time_ms = 0.0;
3967   if (waited) {
3968     double scan_wait_end = os::elapsedTime();
3969     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3970   }
3971   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3972 }
3973 
3974 bool
3975 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3976   assert_at_safepoint(true /* should_be_vm_thread */);
3977   guarantee(!is_gc_active(), "collection is not reentrant");
3978 
3979   if (GC_locker::check_active_before_gc()) {
3980     return false;
3981   }
3982 
3983   _gc_timer_stw->register_gc_start();
3984 
3985   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3986 
3987   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3988   ResourceMark rm;
3989 
3990   wait_for_root_region_scanning();
3991 
3992   G1Log::update_level();
3993   print_heap_before_gc();
3994   trace_heap_before_gc(_gc_tracer_stw);
3995 
3996   verify_region_sets_optional();
3997   verify_dirty_young_regions();
3998 
3999   // This call will decide whether this pause is an initial-mark
4000   // pause. If it is, during_initial_mark_pause() will return true
4001   // for the duration of this pause.
4002   g1_policy()->decide_on_conc_mark_initiation();
4003 
4004   // We do not allow initial-mark to be piggy-backed on a mixed GC.
4005   assert(!collector_state()->during_initial_mark_pause() ||
4006           collector_state()->gcs_are_young(), "sanity");
4007 
4008   // We also do not allow mixed GCs during marking.
4009   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
4010 
4011   // Record whether this pause is an initial mark. When the current
4012   // thread has completed its logging output and it's safe to signal
4013   // the CM thread, the flag's value in the policy has been reset.
4014   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
4015 
4016   // Inner scope for scope based logging, timers, and stats collection
4017   {
4018     EvacuationInfo evacuation_info;
4019 
4020     if (collector_state()->during_initial_mark_pause()) {
4021       // We are about to start a marking cycle, so we increment the
4022       // full collection counter.
4023       increment_old_marking_cycles_started();
4024       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4025     }
4026 
4027     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4028 
4029     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4030 
4031     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4032                                                                   workers()->active_workers(),
4033                                                                   Threads::number_of_non_daemon_threads());
4034     workers()->set_active_workers(active_workers);
4035 
4036     double pause_start_sec = os::elapsedTime();
4037     g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4038     log_gc_header();
4039 
4040     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4041     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4042 
4043     // If the secondary_free_list is not empty, append it to the
4044     // free_list. No need to wait for the cleanup operation to finish;
4045     // the region allocation code will check the secondary_free_list
4046     // and wait if necessary. If the G1StressConcRegionFreeing flag is
4047     // set, skip this step so that the region allocation code has to
4048     // get entries from the secondary_free_list.
4049     if (!G1StressConcRegionFreeing) {
4050       append_secondary_free_list_if_not_empty_with_lock();
4051     }
4052 
4053     assert(check_young_list_well_formed(), "young list should be well formed");
4054 
4055     // Don't dynamically change the number of GC threads this early.  A value of
4056     // 0 is used to indicate serial work.  When parallel work is done,
4057     // it will be set.
4058 
4059     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4060       IsGCActiveMark x;
4061 
4062       gc_prologue(false);
4063       increment_total_collections(false /* full gc */);
4064       increment_gc_time_stamp();
4065 
4066       verify_before_gc();
4067 
4068       check_bitmaps("GC Start");
4069 
4070       COMPILER2_PRESENT(DerivedPointerTable::clear());
4071 
4072       // Please see comment in g1CollectedHeap.hpp and
4073       // G1CollectedHeap::ref_processing_init() to see how
4074       // reference processing currently works in G1.
4075 
4076       // Enable discovery in the STW reference processor
4077       ref_processor_stw()->enable_discovery();
4078 
4079       {
4080         // We want to temporarily turn off discovery by the
4081         // CM ref processor, if necessary, and turn it back on
4082         // on again later if we do. Using a scoped
4083         // NoRefDiscovery object will do this.
4084         NoRefDiscovery no_cm_discovery(ref_processor_cm());
4085 
4086         // Forget the current alloc region (we might even choose it to be part
4087         // of the collection set!).
4088         _allocator->release_mutator_alloc_region();
4089 
4090         // We should call this after we retire the mutator alloc
4091         // region(s) so that all the ALLOC / RETIRE events are generated
4092         // before the start GC event.
4093         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4094 
4095         // This timing is only used by the ergonomics to handle our pause target.
4096         // It is unclear why this should not include the full pause. We will
4097         // investigate this in CR 7178365.
4098         //
4099         // Preserving the old comment here if that helps the investigation:
4100         //
4101         // The elapsed time induced by the start time below deliberately elides
4102         // the possible verification above.
4103         double sample_start_time_sec = os::elapsedTime();
4104 
4105 #if YOUNG_LIST_VERBOSE
4106         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4107         _young_list->print();
4108         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4109 #endif // YOUNG_LIST_VERBOSE
4110 
4111         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4112 
4113 #if YOUNG_LIST_VERBOSE
4114         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4115         _young_list->print();
4116 #endif // YOUNG_LIST_VERBOSE
4117 
4118         if (collector_state()->during_initial_mark_pause()) {
4119           concurrent_mark()->checkpointRootsInitialPre();
4120         }
4121 
4122 #if YOUNG_LIST_VERBOSE
4123         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4124         _young_list->print();
4125         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4126 #endif // YOUNG_LIST_VERBOSE
4127 
4128         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4129 
4130         register_humongous_regions_with_cset();
4131 
4132         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4133 
4134         _cm->note_start_of_gc();
4135         // We call this after finalize_cset() to
4136         // ensure that the CSet has been finalized.
4137         _cm->verify_no_cset_oops();
4138 
4139         if (_hr_printer.is_active()) {
4140           HeapRegion* hr = g1_policy()->collection_set();
4141           while (hr != NULL) {
4142             _hr_printer.cset(hr);
4143             hr = hr->next_in_collection_set();
4144           }
4145         }
4146 
4147 #ifdef ASSERT
4148         VerifyCSetClosure cl;
4149         collection_set_iterate(&cl);
4150 #endif // ASSERT
4151 
4152         setup_surviving_young_words();
4153 
4154         // Initialize the GC alloc regions.
4155         _allocator->init_gc_alloc_regions(evacuation_info);
4156 
4157         // Actually do the work...
4158         evacuate_collection_set(evacuation_info);
4159 
4160         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4161 
4162         eagerly_reclaim_humongous_regions();
4163 
4164         g1_policy()->clear_collection_set();
4165 
4166         cleanup_surviving_young_words();
4167 
4168         // Start a new incremental collection set for the next pause.
4169         g1_policy()->start_incremental_cset_building();
4170 
4171         clear_cset_fast_test();
4172 
4173         _young_list->reset_sampled_info();
4174 
4175         // Don't check the whole heap at this point as the
4176         // GC alloc regions from this pause have been tagged
4177         // as survivors and moved on to the survivor list.
4178         // Survivor regions will fail the !is_young() check.
4179         assert(check_young_list_empty(false /* check_heap */),
4180           "young list should be empty");
4181 
4182 #if YOUNG_LIST_VERBOSE
4183         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4184         _young_list->print();
4185 #endif // YOUNG_LIST_VERBOSE
4186 
4187         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4188                                              _young_list->first_survivor_region(),
4189                                              _young_list->last_survivor_region());
4190 
4191         _young_list->reset_auxilary_lists();
4192 
4193         if (evacuation_failed()) {
4194           set_used(recalculate_used());
4195           if (_archive_allocator != NULL) {
4196             _archive_allocator->clear_used();
4197           }
4198           for (uint i = 0; i < ParallelGCThreads; i++) {
4199             if (_evacuation_failed_info_array[i].has_failed()) {
4200               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4201             }
4202           }
4203         } else {
4204           // The "used" of the the collection set have already been subtracted
4205           // when they were freed.  Add in the bytes evacuated.
4206           increase_used(g1_policy()->bytes_copied_during_gc());
4207         }
4208 
4209         if (collector_state()->during_initial_mark_pause()) {
4210           // We have to do this before we notify the CM threads that
4211           // they can start working to make sure that all the
4212           // appropriate initialization is done on the CM object.
4213           concurrent_mark()->checkpointRootsInitialPost();
4214           collector_state()->set_mark_in_progress(true);
4215           // Note that we don't actually trigger the CM thread at
4216           // this point. We do that later when we're sure that
4217           // the current thread has completed its logging output.
4218         }
4219 
4220         allocate_dummy_regions();
4221 
4222 #if YOUNG_LIST_VERBOSE
4223         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4224         _young_list->print();
4225         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4226 #endif // YOUNG_LIST_VERBOSE
4227 
4228         _allocator->init_mutator_alloc_region();
4229 
4230         {
4231           size_t expand_bytes = g1_policy()->expansion_amount();
4232           if (expand_bytes > 0) {
4233             size_t bytes_before = capacity();
4234             // No need for an ergo verbose message here,
4235             // expansion_amount() does this when it returns a value > 0.
4236             if (!expand(expand_bytes)) {
4237               // We failed to expand the heap. Cannot do anything about it.
4238             }
4239           }
4240         }
4241 
4242         // We redo the verification but now wrt to the new CSet which
4243         // has just got initialized after the previous CSet was freed.
4244         _cm->verify_no_cset_oops();
4245         _cm->note_end_of_gc();
4246 
4247         // This timing is only used by the ergonomics to handle our pause target.
4248         // It is unclear why this should not include the full pause. We will
4249         // investigate this in CR 7178365.
4250         double sample_end_time_sec = os::elapsedTime();
4251         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4252         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4253 
4254         MemoryService::track_memory_usage();
4255 
4256         // In prepare_for_verify() below we'll need to scan the deferred
4257         // update buffers to bring the RSets up-to-date if
4258         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4259         // the update buffers we'll probably need to scan cards on the
4260         // regions we just allocated to (i.e., the GC alloc
4261         // regions). However, during the last GC we called
4262         // set_saved_mark() on all the GC alloc regions, so card
4263         // scanning might skip the [saved_mark_word()...top()] area of
4264         // those regions (i.e., the area we allocated objects into
4265         // during the last GC). But it shouldn't. Given that
4266         // saved_mark_word() is conditional on whether the GC time stamp
4267         // on the region is current or not, by incrementing the GC time
4268         // stamp here we invalidate all the GC time stamps on all the
4269         // regions and saved_mark_word() will simply return top() for
4270         // all the regions. This is a nicer way of ensuring this rather
4271         // than iterating over the regions and fixing them. In fact, the
4272         // GC time stamp increment here also ensures that
4273         // saved_mark_word() will return top() between pauses, i.e.,
4274         // during concurrent refinement. So we don't need the
4275         // is_gc_active() check to decided which top to use when
4276         // scanning cards (see CR 7039627).
4277         increment_gc_time_stamp();
4278 
4279         verify_after_gc();
4280         check_bitmaps("GC End");
4281 
4282         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4283         ref_processor_stw()->verify_no_references_recorded();
4284 
4285         // CM reference discovery will be re-enabled if necessary.
4286       }
4287 
4288       // We should do this after we potentially expand the heap so
4289       // that all the COMMIT events are generated before the end GC
4290       // event, and after we retire the GC alloc regions so that all
4291       // RETIRE events are generated before the end GC event.
4292       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4293 
4294 #ifdef TRACESPINNING
4295       ParallelTaskTerminator::print_termination_counts();
4296 #endif
4297 
4298       gc_epilogue(false);
4299     }
4300 
4301     // Print the remainder of the GC log output.
4302     log_gc_footer(os::elapsedTime() - pause_start_sec);
4303 
4304     // It is not yet to safe to tell the concurrent mark to
4305     // start as we have some optional output below. We don't want the
4306     // output from the concurrent mark thread interfering with this
4307     // logging output either.
4308 
4309     _hrm.verify_optional();
4310     verify_region_sets_optional();
4311 
4312     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4313     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4314 
4315     print_heap_after_gc();
4316     trace_heap_after_gc(_gc_tracer_stw);
4317 
4318     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4319     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4320     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4321     // before any GC notifications are raised.
4322     g1mm()->update_sizes();
4323 
4324     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4325     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4326     _gc_timer_stw->register_gc_end();
4327     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4328   }
4329   // It should now be safe to tell the concurrent mark thread to start
4330   // without its logging output interfering with the logging output
4331   // that came from the pause.
4332 
4333   if (should_start_conc_mark) {
4334     // CAUTION: after the doConcurrentMark() call below,
4335     // the concurrent marking thread(s) could be running
4336     // concurrently with us. Make sure that anything after
4337     // this point does not assume that we are the only GC thread
4338     // running. Note: of course, the actual marking work will
4339     // not start until the safepoint itself is released in
4340     // SuspendibleThreadSet::desynchronize().
4341     doConcurrentMark();
4342   }
4343 
4344   return true;
4345 }
4346 
4347 void G1CollectedHeap::remove_self_forwarding_pointers() {
4348   double remove_self_forwards_start = os::elapsedTime();
4349 
4350   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4351   workers()->run_task(&rsfp_task);
4352 
4353   // Now restore saved marks, if any.
4354   for (uint i = 0; i < ParallelGCThreads; i++) {
4355     OopAndMarkOopStack& cur = _preserved_objs[i];
4356     while (!cur.is_empty()) {
4357       OopAndMarkOop elem = cur.pop();
4358       elem.set_mark();
4359     }
4360     cur.clear(true);
4361   }
4362 
4363   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4364 }
4365 
4366 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4367   if (!_evacuation_failed) {
4368     _evacuation_failed = true;
4369   }
4370 
4371   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4372 
4373   // We want to call the "for_promotion_failure" version only in the
4374   // case of a promotion failure.
4375   if (m->must_be_preserved_for_promotion_failure(obj)) {
4376     OopAndMarkOop elem(obj, m);
4377     _preserved_objs[worker_id].push(elem);
4378   }
4379 }
4380 
4381 void G1ParCopyHelper::mark_object(oop obj) {
4382   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4383 
4384   // We know that the object is not moving so it's safe to read its size.
4385   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4386 }
4387 
4388 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4389   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4390   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4391   assert(from_obj != to_obj, "should not be self-forwarded");
4392 
4393   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4394   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4395 
4396   // The object might be in the process of being copied by another
4397   // worker so we cannot trust that its to-space image is
4398   // well-formed. So we have to read its size from its from-space
4399   // image which we know should not be changing.
4400   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4401 }
4402 
4403 template <class T>
4404 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4405   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4406     _scanned_klass->record_modified_oops();
4407   }
4408 }
4409 
4410 template <G1Barrier barrier, G1Mark do_mark_object>
4411 template <class T>
4412 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4413   T heap_oop = oopDesc::load_heap_oop(p);
4414 
4415   if (oopDesc::is_null(heap_oop)) {
4416     return;
4417   }
4418 
4419   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4420 
4421   assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4422 
4423   const InCSetState state = _g1->in_cset_state(obj);
4424   if (state.is_in_cset()) {
4425     oop forwardee;
4426     markOop m = obj->mark();
4427     if (m->is_marked()) {
4428       forwardee = (oop) m->decode_pointer();
4429     } else {
4430       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4431     }
4432     assert(forwardee != NULL, "forwardee should not be NULL");
4433     oopDesc::encode_store_heap_oop(p, forwardee);
4434     if (do_mark_object != G1MarkNone && forwardee != obj) {
4435       // If the object is self-forwarded we don't need to explicitly
4436       // mark it, the evacuation failure protocol will do so.
4437       mark_forwarded_object(obj, forwardee);
4438     }
4439 
4440     if (barrier == G1BarrierKlass) {
4441       do_klass_barrier(p, forwardee);
4442     }
4443   } else {
4444     if (state.is_humongous()) {
4445       _g1->set_humongous_is_live(obj);
4446     }
4447     // The object is not in collection set. If we're a root scanning
4448     // closure during an initial mark pause then attempt to mark the object.
4449     if (do_mark_object == G1MarkFromRoot) {
4450       mark_object(obj);
4451     }
4452   }
4453 }
4454 
4455 class G1ParEvacuateFollowersClosure : public VoidClosure {
4456 protected:
4457   G1CollectedHeap*              _g1h;
4458   G1ParScanThreadState*         _par_scan_state;
4459   RefToScanQueueSet*            _queues;
4460   ParallelTaskTerminator*       _terminator;
4461 
4462   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4463   RefToScanQueueSet*      queues()         { return _queues; }
4464   ParallelTaskTerminator* terminator()     { return _terminator; }
4465 
4466 public:
4467   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4468                                 G1ParScanThreadState* par_scan_state,
4469                                 RefToScanQueueSet* queues,
4470                                 ParallelTaskTerminator* terminator)
4471     : _g1h(g1h), _par_scan_state(par_scan_state),
4472       _queues(queues), _terminator(terminator) {}
4473 
4474   void do_void();
4475 
4476 private:
4477   inline bool offer_termination();
4478 };
4479 
4480 bool G1ParEvacuateFollowersClosure::offer_termination() {
4481   G1ParScanThreadState* const pss = par_scan_state();
4482   pss->start_term_time();
4483   const bool res = terminator()->offer_termination();
4484   pss->end_term_time();
4485   return res;
4486 }
4487 
4488 void G1ParEvacuateFollowersClosure::do_void() {
4489   G1ParScanThreadState* const pss = par_scan_state();
4490   pss->trim_queue();
4491   do {
4492     pss->steal_and_trim_queue(queues());
4493   } while (!offer_termination());
4494 }
4495 
4496 class G1KlassScanClosure : public KlassClosure {
4497  G1ParCopyHelper* _closure;
4498  bool             _process_only_dirty;
4499  int              _count;
4500  public:
4501   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4502       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4503   void do_klass(Klass* klass) {
4504     // If the klass has not been dirtied we know that there's
4505     // no references into  the young gen and we can skip it.
4506    if (!_process_only_dirty || klass->has_modified_oops()) {
4507       // Clean the klass since we're going to scavenge all the metadata.
4508       klass->clear_modified_oops();
4509 
4510       // Tell the closure that this klass is the Klass to scavenge
4511       // and is the one to dirty if oops are left pointing into the young gen.
4512       _closure->set_scanned_klass(klass);
4513 
4514       klass->oops_do(_closure);
4515 
4516       _closure->set_scanned_klass(NULL);
4517     }
4518     _count++;
4519   }
4520 };
4521 
4522 class G1ParTask : public AbstractGangTask {
4523 protected:
4524   G1CollectedHeap*       _g1h;
4525   RefToScanQueueSet      *_queues;
4526   G1RootProcessor*       _root_processor;
4527   ParallelTaskTerminator _terminator;
4528   uint _n_workers;
4529 
4530 public:
4531   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4532     : AbstractGangTask("G1 collection"),
4533       _g1h(g1h),
4534       _queues(task_queues),
4535       _root_processor(root_processor),
4536       _terminator(n_workers, _queues),
4537       _n_workers(n_workers)
4538   {}
4539 
4540   RefToScanQueueSet* queues() { return _queues; }
4541 
4542   RefToScanQueue *work_queue(int i) {
4543     return queues()->queue(i);
4544   }
4545 
4546   ParallelTaskTerminator* terminator() { return &_terminator; }
4547 
4548   // Helps out with CLD processing.
4549   //
4550   // During InitialMark we need to:
4551   // 1) Scavenge all CLDs for the young GC.
4552   // 2) Mark all objects directly reachable from strong CLDs.
4553   template <G1Mark do_mark_object>
4554   class G1CLDClosure : public CLDClosure {
4555     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4556     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4557     G1KlassScanClosure                                _klass_in_cld_closure;
4558     bool                                              _claim;
4559 
4560    public:
4561     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4562                  bool only_young, bool claim)
4563         : _oop_closure(oop_closure),
4564           _oop_in_klass_closure(oop_closure->g1(),
4565                                 oop_closure->pss(),
4566                                 oop_closure->rp()),
4567           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4568           _claim(claim) {
4569 
4570     }
4571 
4572     void do_cld(ClassLoaderData* cld) {
4573       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4574     }
4575   };
4576 
4577   void work(uint worker_id) {
4578     if (worker_id >= _n_workers) return;  // no work needed this round
4579 
4580     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4581 
4582     {
4583       ResourceMark rm;
4584       HandleMark   hm;
4585 
4586       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4587 
4588       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4589 
4590       bool only_young = _g1h->collector_state()->gcs_are_young();
4591 
4592       // Non-IM young GC.
4593       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4594       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4595                                                                                only_young, // Only process dirty klasses.
4596                                                                                false);     // No need to claim CLDs.
4597       // IM young GC.
4598       //    Strong roots closures.
4599       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4600       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4601                                                                                false, // Process all klasses.
4602                                                                                true); // Need to claim CLDs.
4603       //    Weak roots closures.
4604       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4605       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4606                                                                                     false, // Process all klasses.
4607                                                                                     true); // Need to claim CLDs.
4608 
4609       OopClosure* strong_root_cl;
4610       OopClosure* weak_root_cl;
4611       CLDClosure* strong_cld_cl;
4612       CLDClosure* weak_cld_cl;
4613 
4614       bool trace_metadata = false;
4615 
4616       if (_g1h->collector_state()->during_initial_mark_pause()) {
4617         // We also need to mark copied objects.
4618         strong_root_cl = &scan_mark_root_cl;
4619         strong_cld_cl  = &scan_mark_cld_cl;
4620         if (ClassUnloadingWithConcurrentMark) {
4621           weak_root_cl = &scan_mark_weak_root_cl;
4622           weak_cld_cl  = &scan_mark_weak_cld_cl;
4623           trace_metadata = true;
4624         } else {
4625           weak_root_cl = &scan_mark_root_cl;
4626           weak_cld_cl  = &scan_mark_cld_cl;
4627         }
4628       } else {
4629         strong_root_cl = &scan_only_root_cl;
4630         weak_root_cl   = &scan_only_root_cl;
4631         strong_cld_cl  = &scan_only_cld_cl;
4632         weak_cld_cl    = &scan_only_cld_cl;
4633       }
4634 
4635       pss.start_strong_roots();
4636 
4637       _root_processor->evacuate_roots(strong_root_cl,
4638                                       weak_root_cl,
4639                                       strong_cld_cl,
4640                                       weak_cld_cl,
4641                                       trace_metadata,
4642                                       worker_id);
4643 
4644       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4645       _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4646                                             weak_root_cl,
4647                                             worker_id);
4648       pss.end_strong_roots();
4649 
4650       {
4651         double start = os::elapsedTime();
4652         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4653         evac.do_void();
4654         double elapsed_sec = os::elapsedTime() - start;
4655         double term_sec = pss.term_time();
4656         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4657         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4658         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4659       }
4660       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4661       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4662 
4663       if (PrintTerminationStats) {
4664         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4665         pss.print_termination_stats();
4666       }
4667 
4668       assert(pss.queue_is_empty(), "should be empty");
4669 
4670       // Close the inner scope so that the ResourceMark and HandleMark
4671       // destructors are executed here and are included as part of the
4672       // "GC Worker Time".
4673     }
4674     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4675   }
4676 };
4677 
4678 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4679 private:
4680   BoolObjectClosure* _is_alive;
4681   int _initial_string_table_size;
4682   int _initial_symbol_table_size;
4683 
4684   bool  _process_strings;
4685   int _strings_processed;
4686   int _strings_removed;
4687 
4688   bool  _process_symbols;
4689   int _symbols_processed;
4690   int _symbols_removed;
4691 
4692 public:
4693   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4694     AbstractGangTask("String/Symbol Unlinking"),
4695     _is_alive(is_alive),
4696     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4697     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4698 
4699     _initial_string_table_size = StringTable::the_table()->table_size();
4700     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4701     if (process_strings) {
4702       StringTable::clear_parallel_claimed_index();
4703     }
4704     if (process_symbols) {
4705       SymbolTable::clear_parallel_claimed_index();
4706     }
4707   }
4708 
4709   ~G1StringSymbolTableUnlinkTask() {
4710     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4711               err_msg("claim value %d after unlink less than initial string table size %d",
4712                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4713     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4714               err_msg("claim value %d after unlink less than initial symbol table size %d",
4715                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4716 
4717     if (G1TraceStringSymbolTableScrubbing) {
4718       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4719                              "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4720                              "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4721                              strings_processed(), strings_removed(),
4722                              symbols_processed(), symbols_removed());
4723     }
4724   }
4725 
4726   void work(uint worker_id) {
4727     int strings_processed = 0;
4728     int strings_removed = 0;
4729     int symbols_processed = 0;
4730     int symbols_removed = 0;
4731     if (_process_strings) {
4732       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4733       Atomic::add(strings_processed, &_strings_processed);
4734       Atomic::add(strings_removed, &_strings_removed);
4735     }
4736     if (_process_symbols) {
4737       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4738       Atomic::add(symbols_processed, &_symbols_processed);
4739       Atomic::add(symbols_removed, &_symbols_removed);
4740     }
4741   }
4742 
4743   size_t strings_processed() const { return (size_t)_strings_processed; }
4744   size_t strings_removed()   const { return (size_t)_strings_removed; }
4745 
4746   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4747   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4748 };
4749 
4750 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4751 private:
4752   static Monitor* _lock;
4753 
4754   BoolObjectClosure* const _is_alive;
4755   const bool               _unloading_occurred;
4756   const uint               _num_workers;
4757 
4758   // Variables used to claim nmethods.
4759   nmethod* _first_nmethod;
4760   volatile nmethod* _claimed_nmethod;
4761 
4762   // The list of nmethods that need to be processed by the second pass.
4763   volatile nmethod* _postponed_list;
4764   volatile uint     _num_entered_barrier;
4765 
4766  public:
4767   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4768       _is_alive(is_alive),
4769       _unloading_occurred(unloading_occurred),
4770       _num_workers(num_workers),
4771       _first_nmethod(NULL),
4772       _claimed_nmethod(NULL),
4773       _postponed_list(NULL),
4774       _num_entered_barrier(0)
4775   {
4776     nmethod::increase_unloading_clock();
4777     // Get first alive nmethod
4778     NMethodIterator iter = NMethodIterator();
4779     if(iter.next_alive()) {
4780       _first_nmethod = iter.method();
4781     }
4782     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4783   }
4784 
4785   ~G1CodeCacheUnloadingTask() {
4786     CodeCache::verify_clean_inline_caches();
4787 
4788     CodeCache::set_needs_cache_clean(false);
4789     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4790 
4791     CodeCache::verify_icholder_relocations();
4792   }
4793 
4794  private:
4795   void add_to_postponed_list(nmethod* nm) {
4796       nmethod* old;
4797       do {
4798         old = (nmethod*)_postponed_list;
4799         nm->set_unloading_next(old);
4800       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4801   }
4802 
4803   void clean_nmethod(nmethod* nm) {
4804     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4805 
4806     if (postponed) {
4807       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4808       add_to_postponed_list(nm);
4809     }
4810 
4811     // Mark that this thread has been cleaned/unloaded.
4812     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4813     nm->set_unloading_clock(nmethod::global_unloading_clock());
4814   }
4815 
4816   void clean_nmethod_postponed(nmethod* nm) {
4817     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4818   }
4819 
4820   static const int MaxClaimNmethods = 16;
4821 
4822   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4823     nmethod* first;
4824     NMethodIterator last;
4825 
4826     do {
4827       *num_claimed_nmethods = 0;
4828 
4829       first = (nmethod*)_claimed_nmethod;
4830       last = NMethodIterator(first);
4831 
4832       if (first != NULL) {
4833 
4834         for (int i = 0; i < MaxClaimNmethods; i++) {
4835           if (!last.next_alive()) {
4836             break;
4837           }
4838           claimed_nmethods[i] = last.method();
4839           (*num_claimed_nmethods)++;
4840         }
4841       }
4842 
4843     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4844   }
4845 
4846   nmethod* claim_postponed_nmethod() {
4847     nmethod* claim;
4848     nmethod* next;
4849 
4850     do {
4851       claim = (nmethod*)_postponed_list;
4852       if (claim == NULL) {
4853         return NULL;
4854       }
4855 
4856       next = claim->unloading_next();
4857 
4858     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4859 
4860     return claim;
4861   }
4862 
4863  public:
4864   // Mark that we're done with the first pass of nmethod cleaning.
4865   void barrier_mark(uint worker_id) {
4866     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4867     _num_entered_barrier++;
4868     if (_num_entered_barrier == _num_workers) {
4869       ml.notify_all();
4870     }
4871   }
4872 
4873   // See if we have to wait for the other workers to
4874   // finish their first-pass nmethod cleaning work.
4875   void barrier_wait(uint worker_id) {
4876     if (_num_entered_barrier < _num_workers) {
4877       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4878       while (_num_entered_barrier < _num_workers) {
4879           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4880       }
4881     }
4882   }
4883 
4884   // Cleaning and unloading of nmethods. Some work has to be postponed
4885   // to the second pass, when we know which nmethods survive.
4886   void work_first_pass(uint worker_id) {
4887     // The first nmethods is claimed by the first worker.
4888     if (worker_id == 0 && _first_nmethod != NULL) {
4889       clean_nmethod(_first_nmethod);
4890       _first_nmethod = NULL;
4891     }
4892 
4893     int num_claimed_nmethods;
4894     nmethod* claimed_nmethods[MaxClaimNmethods];
4895 
4896     while (true) {
4897       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4898 
4899       if (num_claimed_nmethods == 0) {
4900         break;
4901       }
4902 
4903       for (int i = 0; i < num_claimed_nmethods; i++) {
4904         clean_nmethod(claimed_nmethods[i]);
4905       }
4906     }
4907   }
4908 
4909   void work_second_pass(uint worker_id) {
4910     nmethod* nm;
4911     // Take care of postponed nmethods.
4912     while ((nm = claim_postponed_nmethod()) != NULL) {
4913       clean_nmethod_postponed(nm);
4914     }
4915   }
4916 };
4917 
4918 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4919 
4920 class G1KlassCleaningTask : public StackObj {
4921   BoolObjectClosure*                      _is_alive;
4922   volatile jint                           _clean_klass_tree_claimed;
4923   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4924 
4925  public:
4926   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4927       _is_alive(is_alive),
4928       _clean_klass_tree_claimed(0),
4929       _klass_iterator() {
4930   }
4931 
4932  private:
4933   bool claim_clean_klass_tree_task() {
4934     if (_clean_klass_tree_claimed) {
4935       return false;
4936     }
4937 
4938     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4939   }
4940 
4941   InstanceKlass* claim_next_klass() {
4942     Klass* klass;
4943     do {
4944       klass =_klass_iterator.next_klass();
4945     } while (klass != NULL && !klass->oop_is_instance());
4946 
4947     return (InstanceKlass*)klass;
4948   }
4949 
4950 public:
4951 
4952   void clean_klass(InstanceKlass* ik) {
4953     ik->clean_implementors_list(_is_alive);
4954     ik->clean_method_data(_is_alive);
4955 
4956     // G1 specific cleanup work that has
4957     // been moved here to be done in parallel.
4958     ik->clean_dependent_nmethods();
4959   }
4960 
4961   void work() {
4962     ResourceMark rm;
4963 
4964     // One worker will clean the subklass/sibling klass tree.
4965     if (claim_clean_klass_tree_task()) {
4966       Klass::clean_subklass_tree(_is_alive);
4967     }
4968 
4969     // All workers will help cleaning the classes,
4970     InstanceKlass* klass;
4971     while ((klass = claim_next_klass()) != NULL) {
4972       clean_klass(klass);
4973     }
4974   }
4975 };
4976 
4977 // To minimize the remark pause times, the tasks below are done in parallel.
4978 class G1ParallelCleaningTask : public AbstractGangTask {
4979 private:
4980   G1StringSymbolTableUnlinkTask _string_symbol_task;
4981   G1CodeCacheUnloadingTask      _code_cache_task;
4982   G1KlassCleaningTask           _klass_cleaning_task;
4983 
4984 public:
4985   // The constructor is run in the VMThread.
4986   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4987       AbstractGangTask("Parallel Cleaning"),
4988       _string_symbol_task(is_alive, process_strings, process_symbols),
4989       _code_cache_task(num_workers, is_alive, unloading_occurred),
4990       _klass_cleaning_task(is_alive) {
4991   }
4992 
4993   // The parallel work done by all worker threads.
4994   void work(uint worker_id) {
4995     // Do first pass of code cache cleaning.
4996     _code_cache_task.work_first_pass(worker_id);
4997 
4998     // Let the threads mark that the first pass is done.
4999     _code_cache_task.barrier_mark(worker_id);
5000 
5001     // Clean the Strings and Symbols.
5002     _string_symbol_task.work(worker_id);
5003 
5004     // Wait for all workers to finish the first code cache cleaning pass.
5005     _code_cache_task.barrier_wait(worker_id);
5006 
5007     // Do the second code cache cleaning work, which realize on
5008     // the liveness information gathered during the first pass.
5009     _code_cache_task.work_second_pass(worker_id);
5010 
5011     // Clean all klasses that were not unloaded.
5012     _klass_cleaning_task.work();
5013   }
5014 };
5015 
5016 
5017 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5018                                         bool process_strings,
5019                                         bool process_symbols,
5020                                         bool class_unloading_occurred) {
5021   uint n_workers = workers()->active_workers();
5022 
5023   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5024                                         n_workers, class_unloading_occurred);
5025   workers()->run_task(&g1_unlink_task);
5026 }
5027 
5028 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5029                                                      bool process_strings, bool process_symbols) {
5030   {
5031     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5032     workers()->run_task(&g1_unlink_task);
5033   }
5034 
5035   if (G1StringDedup::is_enabled()) {
5036     G1StringDedup::unlink(is_alive);
5037   }
5038 }
5039 
5040 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5041  private:
5042   DirtyCardQueueSet* _queue;
5043  public:
5044   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5045 
5046   virtual void work(uint worker_id) {
5047     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5048     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5049 
5050     RedirtyLoggedCardTableEntryClosure cl;
5051     _queue->par_apply_closure_to_all_completed_buffers(&cl);
5052 
5053     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5054   }
5055 };
5056 
5057 void G1CollectedHeap::redirty_logged_cards() {
5058   double redirty_logged_cards_start = os::elapsedTime();
5059 
5060   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5061   dirty_card_queue_set().reset_for_par_iteration();
5062   workers()->run_task(&redirty_task);
5063 
5064   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5065   dcq.merge_bufferlists(&dirty_card_queue_set());
5066   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5067 
5068   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5069 }
5070 
5071 // Weak Reference Processing support
5072 
5073 // An always "is_alive" closure that is used to preserve referents.
5074 // If the object is non-null then it's alive.  Used in the preservation
5075 // of referent objects that are pointed to by reference objects
5076 // discovered by the CM ref processor.
5077 class G1AlwaysAliveClosure: public BoolObjectClosure {
5078   G1CollectedHeap* _g1;
5079 public:
5080   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5081   bool do_object_b(oop p) {
5082     if (p != NULL) {
5083       return true;
5084     }
5085     return false;
5086   }
5087 };
5088 
5089 bool G1STWIsAliveClosure::do_object_b(oop p) {
5090   // An object is reachable if it is outside the collection set,
5091   // or is inside and copied.
5092   return !_g1->is_in_cset(p) || p->is_forwarded();
5093 }
5094 
5095 // Non Copying Keep Alive closure
5096 class G1KeepAliveClosure: public OopClosure {
5097   G1CollectedHeap* _g1;
5098 public:
5099   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5100   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5101   void do_oop(oop* p) {
5102     oop obj = *p;
5103     assert(obj != NULL, "the caller should have filtered out NULL values");
5104 
5105     const InCSetState cset_state = _g1->in_cset_state(obj);
5106     if (!cset_state.is_in_cset_or_humongous()) {
5107       return;
5108     }
5109     if (cset_state.is_in_cset()) {
5110       assert( obj->is_forwarded(), "invariant" );
5111       *p = obj->forwardee();
5112     } else {
5113       assert(!obj->is_forwarded(), "invariant" );
5114       assert(cset_state.is_humongous(),
5115              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5116       _g1->set_humongous_is_live(obj);
5117     }
5118   }
5119 };
5120 
5121 // Copying Keep Alive closure - can be called from both
5122 // serial and parallel code as long as different worker
5123 // threads utilize different G1ParScanThreadState instances
5124 // and different queues.
5125 
5126 class G1CopyingKeepAliveClosure: public OopClosure {
5127   G1CollectedHeap*         _g1h;
5128   OopClosure*              _copy_non_heap_obj_cl;
5129   G1ParScanThreadState*    _par_scan_state;
5130 
5131 public:
5132   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5133                             OopClosure* non_heap_obj_cl,
5134                             G1ParScanThreadState* pss):
5135     _g1h(g1h),
5136     _copy_non_heap_obj_cl(non_heap_obj_cl),
5137     _par_scan_state(pss)
5138   {}
5139 
5140   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5141   virtual void do_oop(      oop* p) { do_oop_work(p); }
5142 
5143   template <class T> void do_oop_work(T* p) {
5144     oop obj = oopDesc::load_decode_heap_oop(p);
5145 
5146     if (_g1h->is_in_cset_or_humongous(obj)) {
5147       // If the referent object has been forwarded (either copied
5148       // to a new location or to itself in the event of an
5149       // evacuation failure) then we need to update the reference
5150       // field and, if both reference and referent are in the G1
5151       // heap, update the RSet for the referent.
5152       //
5153       // If the referent has not been forwarded then we have to keep
5154       // it alive by policy. Therefore we have copy the referent.
5155       //
5156       // If the reference field is in the G1 heap then we can push
5157       // on the PSS queue. When the queue is drained (after each
5158       // phase of reference processing) the object and it's followers
5159       // will be copied, the reference field set to point to the
5160       // new location, and the RSet updated. Otherwise we need to
5161       // use the the non-heap or metadata closures directly to copy
5162       // the referent object and update the pointer, while avoiding
5163       // updating the RSet.
5164 
5165       if (_g1h->is_in_g1_reserved(p)) {
5166         _par_scan_state->push_on_queue(p);
5167       } else {
5168         assert(!Metaspace::contains((const void*)p),
5169                err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5170         _copy_non_heap_obj_cl->do_oop(p);
5171       }
5172     }
5173   }
5174 };
5175 
5176 // Serial drain queue closure. Called as the 'complete_gc'
5177 // closure for each discovered list in some of the
5178 // reference processing phases.
5179 
5180 class G1STWDrainQueueClosure: public VoidClosure {
5181 protected:
5182   G1CollectedHeap* _g1h;
5183   G1ParScanThreadState* _par_scan_state;
5184 
5185   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5186 
5187 public:
5188   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5189     _g1h(g1h),
5190     _par_scan_state(pss)
5191   { }
5192 
5193   void do_void() {
5194     G1ParScanThreadState* const pss = par_scan_state();
5195     pss->trim_queue();
5196   }
5197 };
5198 
5199 // Parallel Reference Processing closures
5200 
5201 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5202 // processing during G1 evacuation pauses.
5203 
5204 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5205 private:
5206   G1CollectedHeap*   _g1h;
5207   RefToScanQueueSet* _queues;
5208   FlexibleWorkGang*  _workers;
5209   uint               _active_workers;
5210 
5211 public:
5212   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5213                            FlexibleWorkGang* workers,
5214                            RefToScanQueueSet *task_queues,
5215                            uint n_workers) :
5216     _g1h(g1h),
5217     _queues(task_queues),
5218     _workers(workers),
5219     _active_workers(n_workers)
5220   {
5221     assert(n_workers > 0, "shouldn't call this otherwise");
5222   }
5223 
5224   // Executes the given task using concurrent marking worker threads.
5225   virtual void execute(ProcessTask& task);
5226   virtual void execute(EnqueueTask& task);
5227 };
5228 
5229 // Gang task for possibly parallel reference processing
5230 
5231 class G1STWRefProcTaskProxy: public AbstractGangTask {
5232   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5233   ProcessTask&     _proc_task;
5234   G1CollectedHeap* _g1h;
5235   RefToScanQueueSet *_task_queues;
5236   ParallelTaskTerminator* _terminator;
5237 
5238 public:
5239   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5240                      G1CollectedHeap* g1h,
5241                      RefToScanQueueSet *task_queues,
5242                      ParallelTaskTerminator* terminator) :
5243     AbstractGangTask("Process reference objects in parallel"),
5244     _proc_task(proc_task),
5245     _g1h(g1h),
5246     _task_queues(task_queues),
5247     _terminator(terminator)
5248   {}
5249 
5250   virtual void work(uint worker_id) {
5251     // The reference processing task executed by a single worker.
5252     ResourceMark rm;
5253     HandleMark   hm;
5254 
5255     G1STWIsAliveClosure is_alive(_g1h);
5256 
5257     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5258 
5259     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5260 
5261     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5262 
5263     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5264 
5265     if (_g1h->collector_state()->during_initial_mark_pause()) {
5266       // We also need to mark copied objects.
5267       copy_non_heap_cl = &copy_mark_non_heap_cl;
5268     }
5269 
5270     // Keep alive closure.
5271     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5272 
5273     // Complete GC closure
5274     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5275 
5276     // Call the reference processing task's work routine.
5277     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5278 
5279     // Note we cannot assert that the refs array is empty here as not all
5280     // of the processing tasks (specifically phase2 - pp2_work) execute
5281     // the complete_gc closure (which ordinarily would drain the queue) so
5282     // the queue may not be empty.
5283   }
5284 };
5285 
5286 // Driver routine for parallel reference processing.
5287 // Creates an instance of the ref processing gang
5288 // task and has the worker threads execute it.
5289 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5290   assert(_workers != NULL, "Need parallel worker threads.");
5291 
5292   ParallelTaskTerminator terminator(_active_workers, _queues);
5293   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5294 
5295   _workers->run_task(&proc_task_proxy);
5296 }
5297 
5298 // Gang task for parallel reference enqueueing.
5299 
5300 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5301   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5302   EnqueueTask& _enq_task;
5303 
5304 public:
5305   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5306     AbstractGangTask("Enqueue reference objects in parallel"),
5307     _enq_task(enq_task)
5308   { }
5309 
5310   virtual void work(uint worker_id) {
5311     _enq_task.work(worker_id);
5312   }
5313 };
5314 
5315 // Driver routine for parallel reference enqueueing.
5316 // Creates an instance of the ref enqueueing gang
5317 // task and has the worker threads execute it.
5318 
5319 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5320   assert(_workers != NULL, "Need parallel worker threads.");
5321 
5322   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5323 
5324   _workers->run_task(&enq_task_proxy);
5325 }
5326 
5327 // End of weak reference support closures
5328 
5329 // Abstract task used to preserve (i.e. copy) any referent objects
5330 // that are in the collection set and are pointed to by reference
5331 // objects discovered by the CM ref processor.
5332 
5333 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5334 protected:
5335   G1CollectedHeap* _g1h;
5336   RefToScanQueueSet      *_queues;
5337   ParallelTaskTerminator _terminator;
5338   uint _n_workers;
5339 
5340 public:
5341   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5342     AbstractGangTask("ParPreserveCMReferents"),
5343     _g1h(g1h),
5344     _queues(task_queues),
5345     _terminator(workers, _queues),
5346     _n_workers(workers)
5347   { }
5348 
5349   void work(uint worker_id) {
5350     ResourceMark rm;
5351     HandleMark   hm;
5352 
5353     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5354     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5355 
5356     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5357 
5358     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5359 
5360     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5361 
5362     if (_g1h->collector_state()->during_initial_mark_pause()) {
5363       // We also need to mark copied objects.
5364       copy_non_heap_cl = &copy_mark_non_heap_cl;
5365     }
5366 
5367     // Is alive closure
5368     G1AlwaysAliveClosure always_alive(_g1h);
5369 
5370     // Copying keep alive closure. Applied to referent objects that need
5371     // to be copied.
5372     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5373 
5374     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5375 
5376     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5377     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5378 
5379     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5380     // So this must be true - but assert just in case someone decides to
5381     // change the worker ids.
5382     assert(worker_id < limit, "sanity");
5383     assert(!rp->discovery_is_atomic(), "check this code");
5384 
5385     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5386     for (uint idx = worker_id; idx < limit; idx += stride) {
5387       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5388 
5389       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5390       while (iter.has_next()) {
5391         // Since discovery is not atomic for the CM ref processor, we
5392         // can see some null referent objects.
5393         iter.load_ptrs(DEBUG_ONLY(true));
5394         oop ref = iter.obj();
5395 
5396         // This will filter nulls.
5397         if (iter.is_referent_alive()) {
5398           iter.make_referent_alive();
5399         }
5400         iter.move_to_next();
5401       }
5402     }
5403 
5404     // Drain the queue - which may cause stealing
5405     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5406     drain_queue.do_void();
5407     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5408     assert(pss.queue_is_empty(), "should be");
5409   }
5410 };
5411 
5412 // Weak Reference processing during an evacuation pause (part 1).
5413 void G1CollectedHeap::process_discovered_references() {
5414   double ref_proc_start = os::elapsedTime();
5415 
5416   ReferenceProcessor* rp = _ref_processor_stw;
5417   assert(rp->discovery_enabled(), "should have been enabled");
5418 
5419   // Any reference objects, in the collection set, that were 'discovered'
5420   // by the CM ref processor should have already been copied (either by
5421   // applying the external root copy closure to the discovered lists, or
5422   // by following an RSet entry).
5423   //
5424   // But some of the referents, that are in the collection set, that these
5425   // reference objects point to may not have been copied: the STW ref
5426   // processor would have seen that the reference object had already
5427   // been 'discovered' and would have skipped discovering the reference,
5428   // but would not have treated the reference object as a regular oop.
5429   // As a result the copy closure would not have been applied to the
5430   // referent object.
5431   //
5432   // We need to explicitly copy these referent objects - the references
5433   // will be processed at the end of remarking.
5434   //
5435   // We also need to do this copying before we process the reference
5436   // objects discovered by the STW ref processor in case one of these
5437   // referents points to another object which is also referenced by an
5438   // object discovered by the STW ref processor.
5439 
5440   uint no_of_gc_workers = workers()->active_workers();
5441 
5442   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5443                                                  no_of_gc_workers,
5444                                                  _task_queues);
5445 
5446   workers()->run_task(&keep_cm_referents);
5447 
5448   // Closure to test whether a referent is alive.
5449   G1STWIsAliveClosure is_alive(this);
5450 
5451   // Even when parallel reference processing is enabled, the processing
5452   // of JNI refs is serial and performed serially by the current thread
5453   // rather than by a worker. The following PSS will be used for processing
5454   // JNI refs.
5455 
5456   // Use only a single queue for this PSS.
5457   G1ParScanThreadState            pss(this, 0, NULL);
5458   assert(pss.queue_is_empty(), "pre-condition");
5459 
5460   // We do not embed a reference processor in the copying/scanning
5461   // closures while we're actually processing the discovered
5462   // reference objects.
5463 
5464   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5465 
5466   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5467 
5468   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5469 
5470   if (collector_state()->during_initial_mark_pause()) {
5471     // We also need to mark copied objects.
5472     copy_non_heap_cl = &copy_mark_non_heap_cl;
5473   }
5474 
5475   // Keep alive closure.
5476   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5477 
5478   // Serial Complete GC closure
5479   G1STWDrainQueueClosure drain_queue(this, &pss);
5480 
5481   // Setup the soft refs policy...
5482   rp->setup_policy(false);
5483 
5484   ReferenceProcessorStats stats;
5485   if (!rp->processing_is_mt()) {
5486     // Serial reference processing...
5487     stats = rp->process_discovered_references(&is_alive,
5488                                               &keep_alive,
5489                                               &drain_queue,
5490                                               NULL,
5491                                               _gc_timer_stw,
5492                                               _gc_tracer_stw->gc_id());
5493   } else {
5494     // Parallel reference processing
5495     assert(rp->num_q() == no_of_gc_workers, "sanity");
5496     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5497 
5498     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5499     stats = rp->process_discovered_references(&is_alive,
5500                                               &keep_alive,
5501                                               &drain_queue,
5502                                               &par_task_executor,
5503                                               _gc_timer_stw,
5504                                               _gc_tracer_stw->gc_id());
5505   }
5506 
5507   _gc_tracer_stw->report_gc_reference_stats(stats);
5508 
5509   // We have completed copying any necessary live referent objects.
5510   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5511 
5512   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5513   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5514 }
5515 
5516 // Weak Reference processing during an evacuation pause (part 2).
5517 void G1CollectedHeap::enqueue_discovered_references() {
5518   double ref_enq_start = os::elapsedTime();
5519 
5520   ReferenceProcessor* rp = _ref_processor_stw;
5521   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5522 
5523   // Now enqueue any remaining on the discovered lists on to
5524   // the pending list.
5525   if (!rp->processing_is_mt()) {
5526     // Serial reference processing...
5527     rp->enqueue_discovered_references();
5528   } else {
5529     // Parallel reference enqueueing
5530 
5531     uint n_workers = workers()->active_workers();
5532 
5533     assert(rp->num_q() == n_workers, "sanity");
5534     assert(n_workers <= rp->max_num_q(), "sanity");
5535 
5536     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5537     rp->enqueue_discovered_references(&par_task_executor);
5538   }
5539 
5540   rp->verify_no_references_recorded();
5541   assert(!rp->discovery_enabled(), "should have been disabled");
5542 
5543   // FIXME
5544   // CM's reference processing also cleans up the string and symbol tables.
5545   // Should we do that here also? We could, but it is a serial operation
5546   // and could significantly increase the pause time.
5547 
5548   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5549   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5550 }
5551 
5552 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5553   _expand_heap_after_alloc_failure = true;
5554   _evacuation_failed = false;
5555 
5556   // Should G1EvacuationFailureALot be in effect for this GC?
5557   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5558 
5559   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5560 
5561   // Disable the hot card cache.
5562   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5563   hot_card_cache->reset_hot_cache_claimed_index();
5564   hot_card_cache->set_use_cache(false);
5565 
5566   const uint n_workers = workers()->active_workers();
5567 
5568   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5569   double start_par_time_sec = os::elapsedTime();
5570   double end_par_time_sec;
5571 
5572   {
5573     G1RootProcessor root_processor(this, n_workers);
5574     G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5575     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5576     if (collector_state()->during_initial_mark_pause()) {
5577       ClassLoaderDataGraph::clear_claimed_marks();
5578     }
5579 
5580     // The individual threads will set their evac-failure closures.
5581     if (PrintTerminationStats) {
5582       G1ParScanThreadState::print_termination_stats_hdr();
5583     }
5584 
5585     workers()->run_task(&g1_par_task);
5586     end_par_time_sec = os::elapsedTime();
5587 
5588     // Closing the inner scope will execute the destructor
5589     // for the G1RootProcessor object. We record the current
5590     // elapsed time before closing the scope so that time
5591     // taken for the destructor is NOT included in the
5592     // reported parallel time.
5593   }
5594 
5595   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5596 
5597   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5598   phase_times->record_par_time(par_time_ms);
5599 
5600   double code_root_fixup_time_ms =
5601         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5602   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5603 
5604   // Process any discovered reference objects - we have
5605   // to do this _before_ we retire the GC alloc regions
5606   // as we may have to copy some 'reachable' referent
5607   // objects (and their reachable sub-graphs) that were
5608   // not copied during the pause.
5609   process_discovered_references();
5610 
5611   if (G1StringDedup::is_enabled()) {
5612     double fixup_start = os::elapsedTime();
5613 
5614     G1STWIsAliveClosure is_alive(this);
5615     G1KeepAliveClosure keep_alive(this);
5616     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5617 
5618     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5619     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5620   }
5621 
5622   _allocator->release_gc_alloc_regions(evacuation_info);
5623   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5624 
5625   // Reset and re-enable the hot card cache.
5626   // Note the counts for the cards in the regions in the
5627   // collection set are reset when the collection set is freed.
5628   hot_card_cache->reset_hot_cache();
5629   hot_card_cache->set_use_cache(true);
5630 
5631   purge_code_root_memory();
5632 
5633   if (evacuation_failed()) {
5634     remove_self_forwarding_pointers();
5635 
5636     // Reset the G1EvacuationFailureALot counters and flags
5637     // Note: the values are reset only when an actual
5638     // evacuation failure occurs.
5639     NOT_PRODUCT(reset_evacuation_should_fail();)
5640   }
5641 
5642   // Enqueue any remaining references remaining on the STW
5643   // reference processor's discovered lists. We need to do
5644   // this after the card table is cleaned (and verified) as
5645   // the act of enqueueing entries on to the pending list
5646   // will log these updates (and dirty their associated
5647   // cards). We need these updates logged to update any
5648   // RSets.
5649   enqueue_discovered_references();
5650 
5651   redirty_logged_cards();
5652   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5653 }
5654 
5655 void G1CollectedHeap::free_region(HeapRegion* hr,
5656                                   FreeRegionList* free_list,
5657                                   bool par,
5658                                   bool locked) {
5659   assert(!hr->is_free(), "the region should not be free");
5660   assert(!hr->is_empty(), "the region should not be empty");
5661   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5662   assert(free_list != NULL, "pre-condition");
5663 
5664   if (G1VerifyBitmaps) {
5665     MemRegion mr(hr->bottom(), hr->end());
5666     concurrent_mark()->clearRangePrevBitmap(mr);
5667   }
5668 
5669   // Clear the card counts for this region.
5670   // Note: we only need to do this if the region is not young
5671   // (since we don't refine cards in young regions).
5672   if (!hr->is_young()) {
5673     _cg1r->hot_card_cache()->reset_card_counts(hr);
5674   }
5675   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5676   free_list->add_ordered(hr);
5677 }
5678 
5679 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5680                                      FreeRegionList* free_list,
5681                                      bool par) {
5682   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5683   assert(free_list != NULL, "pre-condition");
5684 
5685   size_t hr_capacity = hr->capacity();
5686   // We need to read this before we make the region non-humongous,
5687   // otherwise the information will be gone.
5688   uint last_index = hr->last_hc_index();
5689   hr->clear_humongous();
5690   free_region(hr, free_list, par);
5691 
5692   uint i = hr->hrm_index() + 1;
5693   while (i < last_index) {
5694     HeapRegion* curr_hr = region_at(i);
5695     assert(curr_hr->is_continues_humongous(), "invariant");
5696     curr_hr->clear_humongous();
5697     free_region(curr_hr, free_list, par);
5698     i += 1;
5699   }
5700 }
5701 
5702 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5703                                        const HeapRegionSetCount& humongous_regions_removed) {
5704   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5705     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5706     _old_set.bulk_remove(old_regions_removed);
5707     _humongous_set.bulk_remove(humongous_regions_removed);
5708   }
5709 
5710 }
5711 
5712 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5713   assert(list != NULL, "list can't be null");
5714   if (!list->is_empty()) {
5715     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5716     _hrm.insert_list_into_free_list(list);
5717   }
5718 }
5719 
5720 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5721   decrease_used(bytes);
5722 }
5723 
5724 class G1ParCleanupCTTask : public AbstractGangTask {
5725   G1SATBCardTableModRefBS* _ct_bs;
5726   G1CollectedHeap* _g1h;
5727   HeapRegion* volatile _su_head;
5728 public:
5729   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5730                      G1CollectedHeap* g1h) :
5731     AbstractGangTask("G1 Par Cleanup CT Task"),
5732     _ct_bs(ct_bs), _g1h(g1h) { }
5733 
5734   void work(uint worker_id) {
5735     HeapRegion* r;
5736     while (r = _g1h->pop_dirty_cards_region()) {
5737       clear_cards(r);
5738     }
5739   }
5740 
5741   void clear_cards(HeapRegion* r) {
5742     // Cards of the survivors should have already been dirtied.
5743     if (!r->is_survivor()) {
5744       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5745     }
5746   }
5747 };
5748 
5749 #ifndef PRODUCT
5750 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5751   G1CollectedHeap* _g1h;
5752   G1SATBCardTableModRefBS* _ct_bs;
5753 public:
5754   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5755     : _g1h(g1h), _ct_bs(ct_bs) { }
5756   virtual bool doHeapRegion(HeapRegion* r) {
5757     if (r->is_survivor()) {
5758       _g1h->verify_dirty_region(r);
5759     } else {
5760       _g1h->verify_not_dirty_region(r);
5761     }
5762     return false;
5763   }
5764 };
5765 
5766 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5767   // All of the region should be clean.
5768   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5769   MemRegion mr(hr->bottom(), hr->end());
5770   ct_bs->verify_not_dirty_region(mr);
5771 }
5772 
5773 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5774   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5775   // dirty allocated blocks as they allocate them. The thread that
5776   // retires each region and replaces it with a new one will do a
5777   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5778   // not dirty that area (one less thing to have to do while holding
5779   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5780   // is dirty.
5781   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5782   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5783   if (hr->is_young()) {
5784     ct_bs->verify_g1_young_region(mr);
5785   } else {
5786     ct_bs->verify_dirty_region(mr);
5787   }
5788 }
5789 
5790 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5791   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5792   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5793     verify_dirty_region(hr);
5794   }
5795 }
5796 
5797 void G1CollectedHeap::verify_dirty_young_regions() {
5798   verify_dirty_young_list(_young_list->first_region());
5799 }
5800 
5801 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5802                                                HeapWord* tams, HeapWord* end) {
5803   guarantee(tams <= end,
5804             err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5805   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5806   if (result < end) {
5807     gclog_or_tty->cr();
5808     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5809                            bitmap_name, p2i(result));
5810     gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5811                            bitmap_name, p2i(tams), p2i(end));
5812     return false;
5813   }
5814   return true;
5815 }
5816 
5817 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5818   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5819   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5820 
5821   HeapWord* bottom = hr->bottom();
5822   HeapWord* ptams  = hr->prev_top_at_mark_start();
5823   HeapWord* ntams  = hr->next_top_at_mark_start();
5824   HeapWord* end    = hr->end();
5825 
5826   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5827 
5828   bool res_n = true;
5829   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5830   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5831   // if we happen to be in that state.
5832   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5833     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5834   }
5835   if (!res_p || !res_n) {
5836     gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5837                            HR_FORMAT_PARAMS(hr));
5838     gclog_or_tty->print_cr("#### Caller: %s", caller);
5839     return false;
5840   }
5841   return true;
5842 }
5843 
5844 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5845   if (!G1VerifyBitmaps) return;
5846 
5847   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5848 }
5849 
5850 class G1VerifyBitmapClosure : public HeapRegionClosure {
5851 private:
5852   const char* _caller;
5853   G1CollectedHeap* _g1h;
5854   bool _failures;
5855 
5856 public:
5857   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5858     _caller(caller), _g1h(g1h), _failures(false) { }
5859 
5860   bool failures() { return _failures; }
5861 
5862   virtual bool doHeapRegion(HeapRegion* hr) {
5863     if (hr->is_continues_humongous()) return false;
5864 
5865     bool result = _g1h->verify_bitmaps(_caller, hr);
5866     if (!result) {
5867       _failures = true;
5868     }
5869     return false;
5870   }
5871 };
5872 
5873 void G1CollectedHeap::check_bitmaps(const char* caller) {
5874   if (!G1VerifyBitmaps) return;
5875 
5876   G1VerifyBitmapClosure cl(caller, this);
5877   heap_region_iterate(&cl);
5878   guarantee(!cl.failures(), "bitmap verification");
5879 }
5880 
5881 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5882  private:
5883   bool _failures;
5884  public:
5885   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5886 
5887   virtual bool doHeapRegion(HeapRegion* hr) {
5888     uint i = hr->hrm_index();
5889     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5890     if (hr->is_humongous()) {
5891       if (hr->in_collection_set()) {
5892         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5893         _failures = true;
5894         return true;
5895       }
5896       if (cset_state.is_in_cset()) {
5897         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5898         _failures = true;
5899         return true;
5900       }
5901       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5902         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5903         _failures = true;
5904         return true;
5905       }
5906     } else {
5907       if (cset_state.is_humongous()) {
5908         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5909         _failures = true;
5910         return true;
5911       }
5912       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5913         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5914                                hr->in_collection_set(), cset_state.value(), i);
5915         _failures = true;
5916         return true;
5917       }
5918       if (cset_state.is_in_cset()) {
5919         if (hr->is_young() != (cset_state.is_young())) {
5920           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5921                                  hr->is_young(), cset_state.value(), i);
5922           _failures = true;
5923           return true;
5924         }
5925         if (hr->is_old() != (cset_state.is_old())) {
5926           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5927                                  hr->is_old(), cset_state.value(), i);
5928           _failures = true;
5929           return true;
5930         }
5931       }
5932     }
5933     return false;
5934   }
5935 
5936   bool failures() const { return _failures; }
5937 };
5938 
5939 bool G1CollectedHeap::check_cset_fast_test() {
5940   G1CheckCSetFastTableClosure cl;
5941   _hrm.iterate(&cl);
5942   return !cl.failures();
5943 }
5944 #endif // PRODUCT
5945 
5946 void G1CollectedHeap::cleanUpCardTable() {
5947   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5948   double start = os::elapsedTime();
5949 
5950   {
5951     // Iterate over the dirty cards region list.
5952     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5953 
5954     workers()->run_task(&cleanup_task);
5955 #ifndef PRODUCT
5956     if (G1VerifyCTCleanup || VerifyAfterGC) {
5957       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5958       heap_region_iterate(&cleanup_verifier);
5959     }
5960 #endif
5961   }
5962 
5963   double elapsed = os::elapsedTime() - start;
5964   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5965 }
5966 
5967 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5968   size_t pre_used = 0;
5969   FreeRegionList local_free_list("Local List for CSet Freeing");
5970 
5971   double young_time_ms     = 0.0;
5972   double non_young_time_ms = 0.0;
5973 
5974   // Since the collection set is a superset of the the young list,
5975   // all we need to do to clear the young list is clear its
5976   // head and length, and unlink any young regions in the code below
5977   _young_list->clear();
5978 
5979   G1CollectorPolicy* policy = g1_policy();
5980 
5981   double start_sec = os::elapsedTime();
5982   bool non_young = true;
5983 
5984   HeapRegion* cur = cs_head;
5985   int age_bound = -1;
5986   size_t rs_lengths = 0;
5987 
5988   while (cur != NULL) {
5989     assert(!is_on_master_free_list(cur), "sanity");
5990     if (non_young) {
5991       if (cur->is_young()) {
5992         double end_sec = os::elapsedTime();
5993         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5994         non_young_time_ms += elapsed_ms;
5995 
5996         start_sec = os::elapsedTime();
5997         non_young = false;
5998       }
5999     } else {
6000       if (!cur->is_young()) {
6001         double end_sec = os::elapsedTime();
6002         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6003         young_time_ms += elapsed_ms;
6004 
6005         start_sec = os::elapsedTime();
6006         non_young = true;
6007       }
6008     }
6009 
6010     rs_lengths += cur->rem_set()->occupied_locked();
6011 
6012     HeapRegion* next = cur->next_in_collection_set();
6013     assert(cur->in_collection_set(), "bad CS");
6014     cur->set_next_in_collection_set(NULL);
6015     clear_in_cset(cur);
6016 
6017     if (cur->is_young()) {
6018       int index = cur->young_index_in_cset();
6019       assert(index != -1, "invariant");
6020       assert((uint) index < policy->young_cset_region_length(), "invariant");
6021       size_t words_survived = _surviving_young_words[index];
6022       cur->record_surv_words_in_group(words_survived);
6023 
6024       // At this point the we have 'popped' cur from the collection set
6025       // (linked via next_in_collection_set()) but it is still in the
6026       // young list (linked via next_young_region()). Clear the
6027       // _next_young_region field.
6028       cur->set_next_young_region(NULL);
6029     } else {
6030       int index = cur->young_index_in_cset();
6031       assert(index == -1, "invariant");
6032     }
6033 
6034     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6035             (!cur->is_young() && cur->young_index_in_cset() == -1),
6036             "invariant" );
6037 
6038     if (!cur->evacuation_failed()) {
6039       MemRegion used_mr = cur->used_region();
6040 
6041       // And the region is empty.
6042       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6043       pre_used += cur->used();
6044       free_region(cur, &local_free_list, false /* par */, true /* locked */);
6045     } else {
6046       cur->uninstall_surv_rate_group();
6047       if (cur->is_young()) {
6048         cur->set_young_index_in_cset(-1);
6049       }
6050       cur->set_evacuation_failed(false);
6051       // The region is now considered to be old.
6052       cur->set_old();
6053       _old_set.add(cur);
6054       evacuation_info.increment_collectionset_used_after(cur->used());
6055     }
6056     cur = next;
6057   }
6058 
6059   evacuation_info.set_regions_freed(local_free_list.length());
6060   policy->record_max_rs_lengths(rs_lengths);
6061   policy->cset_regions_freed();
6062 
6063   double end_sec = os::elapsedTime();
6064   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6065 
6066   if (non_young) {
6067     non_young_time_ms += elapsed_ms;
6068   } else {
6069     young_time_ms += elapsed_ms;
6070   }
6071 
6072   prepend_to_freelist(&local_free_list);
6073   decrement_summary_bytes(pre_used);
6074   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6075   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6076 }
6077 
6078 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6079  private:
6080   FreeRegionList* _free_region_list;
6081   HeapRegionSet* _proxy_set;
6082   HeapRegionSetCount _humongous_regions_removed;
6083   size_t _freed_bytes;
6084  public:
6085 
6086   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6087     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6088   }
6089 
6090   virtual bool doHeapRegion(HeapRegion* r) {
6091     if (!r->is_starts_humongous()) {
6092       return false;
6093     }
6094 
6095     G1CollectedHeap* g1h = G1CollectedHeap::heap();
6096 
6097     oop obj = (oop)r->bottom();
6098     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6099 
6100     // The following checks whether the humongous object is live are sufficient.
6101     // The main additional check (in addition to having a reference from the roots
6102     // or the young gen) is whether the humongous object has a remembered set entry.
6103     //
6104     // A humongous object cannot be live if there is no remembered set for it
6105     // because:
6106     // - there can be no references from within humongous starts regions referencing
6107     // the object because we never allocate other objects into them.
6108     // (I.e. there are no intra-region references that may be missed by the
6109     // remembered set)
6110     // - as soon there is a remembered set entry to the humongous starts region
6111     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6112     // until the end of a concurrent mark.
6113     //
6114     // It is not required to check whether the object has been found dead by marking
6115     // or not, in fact it would prevent reclamation within a concurrent cycle, as
6116     // all objects allocated during that time are considered live.
6117     // SATB marking is even more conservative than the remembered set.
6118     // So if at this point in the collection there is no remembered set entry,
6119     // nobody has a reference to it.
6120     // At the start of collection we flush all refinement logs, and remembered sets
6121     // are completely up-to-date wrt to references to the humongous object.
6122     //
6123     // Other implementation considerations:
6124     // - never consider object arrays at this time because they would pose
6125     // considerable effort for cleaning up the the remembered sets. This is
6126     // required because stale remembered sets might reference locations that
6127     // are currently allocated into.
6128     uint region_idx = r->hrm_index();
6129     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6130         !r->rem_set()->is_empty()) {
6131 
6132       if (G1TraceEagerReclaimHumongousObjects) {
6133         gclog_or_tty->print_cr("Live humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
6134                                region_idx,
6135                                (size_t)obj->size() * HeapWordSize,
6136                                p2i(r->bottom()),
6137                                r->region_num(),
6138                                r->rem_set()->occupied(),
6139                                r->rem_set()->strong_code_roots_list_length(),
6140                                next_bitmap->isMarked(r->bottom()),
6141                                g1h->is_humongous_reclaim_candidate(region_idx),
6142                                obj->is_typeArray()
6143                               );
6144       }
6145 
6146       return false;
6147     }
6148 
6149     guarantee(obj->is_typeArray(),
6150               err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6151                       PTR_FORMAT " is not.",
6152                       p2i(r->bottom())));
6153 
6154     if (G1TraceEagerReclaimHumongousObjects) {
6155       gclog_or_tty->print_cr("Dead humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
6156                              region_idx,
6157                              (size_t)obj->size() * HeapWordSize,
6158                              p2i(r->bottom()),
6159                              r->region_num(),
6160                              r->rem_set()->occupied(),
6161                              r->rem_set()->strong_code_roots_list_length(),
6162                              next_bitmap->isMarked(r->bottom()),
6163                              g1h->is_humongous_reclaim_candidate(region_idx),
6164                              obj->is_typeArray()
6165                             );
6166     }
6167     // Need to clear mark bit of the humongous object if already set.
6168     if (next_bitmap->isMarked(r->bottom())) {
6169       next_bitmap->clear(r->bottom());
6170     }
6171     _freed_bytes += r->used();
6172     r->set_containing_set(NULL);
6173     _humongous_regions_removed.increment(1u, r->capacity());
6174     g1h->free_humongous_region(r, _free_region_list, false);
6175 
6176     return false;
6177   }
6178 
6179   HeapRegionSetCount& humongous_free_count() {
6180     return _humongous_regions_removed;
6181   }
6182 
6183   size_t bytes_freed() const {
6184     return _freed_bytes;
6185   }
6186 
6187   size_t humongous_reclaimed() const {
6188     return _humongous_regions_removed.length();
6189   }
6190 };
6191 
6192 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6193   assert_at_safepoint(true);
6194 
6195   if (!G1EagerReclaimHumongousObjects ||
6196       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6197     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6198     return;
6199   }
6200 
6201   double start_time = os::elapsedTime();
6202 
6203   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6204 
6205   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6206   heap_region_iterate(&cl);
6207 
6208   HeapRegionSetCount empty_set;
6209   remove_from_old_sets(empty_set, cl.humongous_free_count());
6210 
6211   G1HRPrinter* hrp = hr_printer();
6212   if (hrp->is_active()) {
6213     FreeRegionListIterator iter(&local_cleanup_list);
6214     while (iter.more_available()) {
6215       HeapRegion* hr = iter.get_next();
6216       hrp->cleanup(hr);
6217     }
6218   }
6219 
6220   prepend_to_freelist(&local_cleanup_list);
6221   decrement_summary_bytes(cl.bytes_freed());
6222 
6223   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6224                                                                     cl.humongous_reclaimed());
6225 }
6226 
6227 // This routine is similar to the above but does not record
6228 // any policy statistics or update free lists; we are abandoning
6229 // the current incremental collection set in preparation of a
6230 // full collection. After the full GC we will start to build up
6231 // the incremental collection set again.
6232 // This is only called when we're doing a full collection
6233 // and is immediately followed by the tearing down of the young list.
6234 
6235 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6236   HeapRegion* cur = cs_head;
6237 
6238   while (cur != NULL) {
6239     HeapRegion* next = cur->next_in_collection_set();
6240     assert(cur->in_collection_set(), "bad CS");
6241     cur->set_next_in_collection_set(NULL);
6242     clear_in_cset(cur);
6243     cur->set_young_index_in_cset(-1);
6244     cur = next;
6245   }
6246 }
6247 
6248 void G1CollectedHeap::set_free_regions_coming() {
6249   if (G1ConcRegionFreeingVerbose) {
6250     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6251                            "setting free regions coming");
6252   }
6253 
6254   assert(!free_regions_coming(), "pre-condition");
6255   _free_regions_coming = true;
6256 }
6257 
6258 void G1CollectedHeap::reset_free_regions_coming() {
6259   assert(free_regions_coming(), "pre-condition");
6260 
6261   {
6262     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6263     _free_regions_coming = false;
6264     SecondaryFreeList_lock->notify_all();
6265   }
6266 
6267   if (G1ConcRegionFreeingVerbose) {
6268     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6269                            "reset free regions coming");
6270   }
6271 }
6272 
6273 void G1CollectedHeap::wait_while_free_regions_coming() {
6274   // Most of the time we won't have to wait, so let's do a quick test
6275   // first before we take the lock.
6276   if (!free_regions_coming()) {
6277     return;
6278   }
6279 
6280   if (G1ConcRegionFreeingVerbose) {
6281     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6282                            "waiting for free regions");
6283   }
6284 
6285   {
6286     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6287     while (free_regions_coming()) {
6288       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6289     }
6290   }
6291 
6292   if (G1ConcRegionFreeingVerbose) {
6293     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6294                            "done waiting for free regions");
6295   }
6296 }
6297 
6298 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6299   _young_list->push_region(hr);
6300 }
6301 
6302 class NoYoungRegionsClosure: public HeapRegionClosure {
6303 private:
6304   bool _success;
6305 public:
6306   NoYoungRegionsClosure() : _success(true) { }
6307   bool doHeapRegion(HeapRegion* r) {
6308     if (r->is_young()) {
6309       gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6310                              p2i(r->bottom()), p2i(r->end()));
6311       _success = false;
6312     }
6313     return false;
6314   }
6315   bool success() { return _success; }
6316 };
6317 
6318 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6319   bool ret = _young_list->check_list_empty(check_sample);
6320 
6321   if (check_heap) {
6322     NoYoungRegionsClosure closure;
6323     heap_region_iterate(&closure);
6324     ret = ret && closure.success();
6325   }
6326 
6327   return ret;
6328 }
6329 
6330 class TearDownRegionSetsClosure : public HeapRegionClosure {
6331 private:
6332   HeapRegionSet *_old_set;
6333 
6334 public:
6335   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6336 
6337   bool doHeapRegion(HeapRegion* r) {
6338     if (r->is_old()) {
6339       _old_set->remove(r);
6340     } else {
6341       // We ignore free regions, we'll empty the free list afterwards.
6342       // We ignore young regions, we'll empty the young list afterwards.
6343       // We ignore humongous regions, we're not tearing down the
6344       // humongous regions set.
6345       assert(r->is_free() || r->is_young() || r->is_humongous(),
6346              "it cannot be another type");
6347     }
6348     return false;
6349   }
6350 
6351   ~TearDownRegionSetsClosure() {
6352     assert(_old_set->is_empty(), "post-condition");
6353   }
6354 };
6355 
6356 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6357   assert_at_safepoint(true /* should_be_vm_thread */);
6358 
6359   if (!free_list_only) {
6360     TearDownRegionSetsClosure cl(&_old_set);
6361     heap_region_iterate(&cl);
6362 
6363     // Note that emptying the _young_list is postponed and instead done as
6364     // the first step when rebuilding the regions sets again. The reason for
6365     // this is that during a full GC string deduplication needs to know if
6366     // a collected region was young or old when the full GC was initiated.
6367   }
6368   _hrm.remove_all_free_regions();
6369 }
6370 
6371 void G1CollectedHeap::increase_used(size_t bytes) {
6372   _summary_bytes_used += bytes;
6373 }
6374 
6375 void G1CollectedHeap::decrease_used(size_t bytes) {
6376   assert(_summary_bytes_used >= bytes,
6377          err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6378                  _summary_bytes_used, bytes));
6379   _summary_bytes_used -= bytes;
6380 }
6381 
6382 void G1CollectedHeap::set_used(size_t bytes) {
6383   _summary_bytes_used = bytes;
6384 }
6385 
6386 class RebuildRegionSetsClosure : public HeapRegionClosure {
6387 private:
6388   bool            _free_list_only;
6389   HeapRegionSet*   _old_set;
6390   HeapRegionManager*   _hrm;
6391   size_t          _total_used;
6392 
6393 public:
6394   RebuildRegionSetsClosure(bool free_list_only,
6395                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6396     _free_list_only(free_list_only),
6397     _old_set(old_set), _hrm(hrm), _total_used(0) {
6398     assert(_hrm->num_free_regions() == 0, "pre-condition");
6399     if (!free_list_only) {
6400       assert(_old_set->is_empty(), "pre-condition");
6401     }
6402   }
6403 
6404   bool doHeapRegion(HeapRegion* r) {
6405     if (r->is_continues_humongous()) {
6406       return false;
6407     }
6408 
6409     if (r->is_empty()) {
6410       // Add free regions to the free list
6411       r->set_free();
6412       r->set_allocation_context(AllocationContext::system());
6413       _hrm->insert_into_free_list(r);
6414     } else if (!_free_list_only) {
6415       assert(!r->is_young(), "we should not come across young regions");
6416 
6417       if (r->is_humongous()) {
6418         // We ignore humongous regions. We left the humongous set unchanged.
6419       } else {
6420         // Objects that were compacted would have ended up on regions
6421         // that were previously old or free.  Archive regions (which are
6422         // old) will not have been touched.
6423         assert(r->is_free() || r->is_old(), "invariant");
6424         // We now consider them old, so register as such. Leave
6425         // archive regions set that way, however, while still adding
6426         // them to the old set.
6427         if (!r->is_archive()) {
6428           r->set_old();
6429         }
6430         _old_set->add(r);
6431       }
6432       _total_used += r->used();
6433     }
6434 
6435     return false;
6436   }
6437 
6438   size_t total_used() {
6439     return _total_used;
6440   }
6441 };
6442 
6443 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6444   assert_at_safepoint(true /* should_be_vm_thread */);
6445 
6446   if (!free_list_only) {
6447     _young_list->empty_list();
6448   }
6449 
6450   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6451   heap_region_iterate(&cl);
6452 
6453   if (!free_list_only) {
6454     set_used(cl.total_used());
6455     if (_archive_allocator != NULL) {
6456       _archive_allocator->clear_used();
6457     }
6458   }
6459   assert(used_unlocked() == recalculate_used(),
6460          err_msg("inconsistent used_unlocked(), "
6461                  "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6462                  used_unlocked(), recalculate_used()));
6463 }
6464 
6465 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6466   _refine_cte_cl->set_concurrent(concurrent);
6467 }
6468 
6469 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6470   HeapRegion* hr = heap_region_containing(p);
6471   return hr->is_in(p);
6472 }
6473 
6474 // Methods for the mutator alloc region
6475 
6476 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6477                                                       bool force) {
6478   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6479   assert(!force || g1_policy()->can_expand_young_list(),
6480          "if force is true we should be able to expand the young list");
6481   bool young_list_full = g1_policy()->is_young_list_full();
6482   if (force || !young_list_full) {
6483     HeapRegion* new_alloc_region = new_region(word_size,
6484                                               false /* is_old */,
6485                                               false /* do_expand */);
6486     if (new_alloc_region != NULL) {
6487       set_region_short_lived_locked(new_alloc_region);
6488       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6489       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6490       return new_alloc_region;
6491     }
6492   }
6493   return NULL;
6494 }
6495 
6496 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6497                                                   size_t allocated_bytes) {
6498   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6499   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6500 
6501   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6502   increase_used(allocated_bytes);
6503   _hr_printer.retire(alloc_region);
6504   // We update the eden sizes here, when the region is retired,
6505   // instead of when it's allocated, since this is the point that its
6506   // used space has been recored in _summary_bytes_used.
6507   g1mm()->update_eden_size();
6508 }
6509 
6510 // Methods for the GC alloc regions
6511 
6512 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6513                                                  uint count,
6514                                                  InCSetState dest) {
6515   assert(FreeList_lock->owned_by_self(), "pre-condition");
6516 
6517   if (count < g1_policy()->max_regions(dest)) {
6518     const bool is_survivor = (dest.is_young());
6519     HeapRegion* new_alloc_region = new_region(word_size,
6520                                               !is_survivor,
6521                                               true /* do_expand */);
6522     if (new_alloc_region != NULL) {
6523       // We really only need to do this for old regions given that we
6524       // should never scan survivors. But it doesn't hurt to do it
6525       // for survivors too.
6526       new_alloc_region->record_timestamp();
6527       if (is_survivor) {
6528         new_alloc_region->set_survivor();
6529         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6530         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6531       } else {
6532         new_alloc_region->set_old();
6533         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6534         check_bitmaps("Old Region Allocation", new_alloc_region);
6535       }
6536       bool during_im = collector_state()->during_initial_mark_pause();
6537       new_alloc_region->note_start_of_copying(during_im);
6538       return new_alloc_region;
6539     }
6540   }
6541   return NULL;
6542 }
6543 
6544 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6545                                              size_t allocated_bytes,
6546                                              InCSetState dest) {
6547   bool during_im = collector_state()->during_initial_mark_pause();
6548   alloc_region->note_end_of_copying(during_im);
6549   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6550   if (dest.is_young()) {
6551     young_list()->add_survivor_region(alloc_region);
6552   } else {
6553     _old_set.add(alloc_region);
6554   }
6555   _hr_printer.retire(alloc_region);
6556 }
6557 
6558 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6559   bool expanded = false;
6560   uint index = _hrm.find_highest_free(&expanded);
6561 
6562   if (index != G1_NO_HRM_INDEX) {
6563     if (expanded) {
6564       ergo_verbose1(ErgoHeapSizing,
6565                     "attempt heap expansion",
6566                     ergo_format_reason("requested address range outside heap bounds")
6567                     ergo_format_byte("region size"),
6568                     HeapRegion::GrainWords * HeapWordSize);
6569     }
6570     _hrm.allocate_free_regions_starting_at(index, 1);
6571     return region_at(index);
6572   }
6573   return NULL;
6574 }
6575 
6576 // Heap region set verification
6577 
6578 class VerifyRegionListsClosure : public HeapRegionClosure {
6579 private:
6580   HeapRegionSet*   _old_set;
6581   HeapRegionSet*   _humongous_set;
6582   HeapRegionManager*   _hrm;
6583 
6584 public:
6585   HeapRegionSetCount _old_count;
6586   HeapRegionSetCount _humongous_count;
6587   HeapRegionSetCount _free_count;
6588 
6589   VerifyRegionListsClosure(HeapRegionSet* old_set,
6590                            HeapRegionSet* humongous_set,
6591                            HeapRegionManager* hrm) :
6592     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6593     _old_count(), _humongous_count(), _free_count(){ }
6594 
6595   bool doHeapRegion(HeapRegion* hr) {
6596     if (hr->is_continues_humongous()) {
6597       return false;
6598     }
6599 
6600     if (hr->is_young()) {
6601       // TODO
6602     } else if (hr->is_starts_humongous()) {
6603       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6604       _humongous_count.increment(1u, hr->capacity());
6605     } else if (hr->is_empty()) {
6606       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6607       _free_count.increment(1u, hr->capacity());
6608     } else if (hr->is_old()) {
6609       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6610       _old_count.increment(1u, hr->capacity());
6611     } else {
6612       // There are no other valid region types. Check for one invalid
6613       // one we can identify: pinned without old or humongous set.
6614       assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6615       ShouldNotReachHere();
6616     }
6617     return false;
6618   }
6619 
6620   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6621     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6622     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6623         old_set->total_capacity_bytes(), _old_count.capacity()));
6624 
6625     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6626     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6627         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6628 
6629     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()));
6630     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6631         free_list->total_capacity_bytes(), _free_count.capacity()));
6632   }
6633 };
6634 
6635 void G1CollectedHeap::verify_region_sets() {
6636   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6637 
6638   // First, check the explicit lists.
6639   _hrm.verify();
6640   {
6641     // Given that a concurrent operation might be adding regions to
6642     // the secondary free list we have to take the lock before
6643     // verifying it.
6644     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6645     _secondary_free_list.verify_list();
6646   }
6647 
6648   // If a concurrent region freeing operation is in progress it will
6649   // be difficult to correctly attributed any free regions we come
6650   // across to the correct free list given that they might belong to
6651   // one of several (free_list, secondary_free_list, any local lists,
6652   // etc.). So, if that's the case we will skip the rest of the
6653   // verification operation. Alternatively, waiting for the concurrent
6654   // operation to complete will have a non-trivial effect on the GC's
6655   // operation (no concurrent operation will last longer than the
6656   // interval between two calls to verification) and it might hide
6657   // any issues that we would like to catch during testing.
6658   if (free_regions_coming()) {
6659     return;
6660   }
6661 
6662   // Make sure we append the secondary_free_list on the free_list so
6663   // that all free regions we will come across can be safely
6664   // attributed to the free_list.
6665   append_secondary_free_list_if_not_empty_with_lock();
6666 
6667   // Finally, make sure that the region accounting in the lists is
6668   // consistent with what we see in the heap.
6669 
6670   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6671   heap_region_iterate(&cl);
6672   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6673 }
6674 
6675 // Optimized nmethod scanning
6676 
6677 class RegisterNMethodOopClosure: public OopClosure {
6678   G1CollectedHeap* _g1h;
6679   nmethod* _nm;
6680 
6681   template <class T> void do_oop_work(T* p) {
6682     T heap_oop = oopDesc::load_heap_oop(p);
6683     if (!oopDesc::is_null(heap_oop)) {
6684       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6685       HeapRegion* hr = _g1h->heap_region_containing(obj);
6686       assert(!hr->is_continues_humongous(),
6687              err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6688                      " starting at " HR_FORMAT,
6689                      p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6690 
6691       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6692       hr->add_strong_code_root_locked(_nm);
6693     }
6694   }
6695 
6696 public:
6697   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6698     _g1h(g1h), _nm(nm) {}
6699 
6700   void do_oop(oop* p)       { do_oop_work(p); }
6701   void do_oop(narrowOop* p) { do_oop_work(p); }
6702 };
6703 
6704 class UnregisterNMethodOopClosure: public OopClosure {
6705   G1CollectedHeap* _g1h;
6706   nmethod* _nm;
6707 
6708   template <class T> void do_oop_work(T* p) {
6709     T heap_oop = oopDesc::load_heap_oop(p);
6710     if (!oopDesc::is_null(heap_oop)) {
6711       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6712       HeapRegion* hr = _g1h->heap_region_containing(obj);
6713       assert(!hr->is_continues_humongous(),
6714              err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6715                      " starting at " HR_FORMAT,
6716                      p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6717 
6718       hr->remove_strong_code_root(_nm);
6719     }
6720   }
6721 
6722 public:
6723   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6724     _g1h(g1h), _nm(nm) {}
6725 
6726   void do_oop(oop* p)       { do_oop_work(p); }
6727   void do_oop(narrowOop* p) { do_oop_work(p); }
6728 };
6729 
6730 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6731   CollectedHeap::register_nmethod(nm);
6732 
6733   guarantee(nm != NULL, "sanity");
6734   RegisterNMethodOopClosure reg_cl(this, nm);
6735   nm->oops_do(&reg_cl);
6736 }
6737 
6738 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6739   CollectedHeap::unregister_nmethod(nm);
6740 
6741   guarantee(nm != NULL, "sanity");
6742   UnregisterNMethodOopClosure reg_cl(this, nm);
6743   nm->oops_do(&reg_cl, true);
6744 }
6745 
6746 void G1CollectedHeap::purge_code_root_memory() {
6747   double purge_start = os::elapsedTime();
6748   G1CodeRootSet::purge();
6749   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6750   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6751 }
6752 
6753 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6754   G1CollectedHeap* _g1h;
6755 
6756 public:
6757   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6758     _g1h(g1h) {}
6759 
6760   void do_code_blob(CodeBlob* cb) {
6761     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6762     if (nm == NULL) {
6763       return;
6764     }
6765 
6766     if (ScavengeRootsInCode) {
6767       _g1h->register_nmethod(nm);
6768     }
6769   }
6770 };
6771 
6772 void G1CollectedHeap::rebuild_strong_code_roots() {
6773   RebuildStrongCodeRootClosure blob_cl(this);
6774   CodeCache::blobs_do(&blob_cl);
6775 }