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/g1AllocRegion.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/orderAccess.inline.hpp"
  69 #include "runtime/vmThread.hpp"
  70 #include "utilities/globalDefinitions.hpp"
  71 #include "utilities/stack.inline.hpp"
  72 
  73 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  74 
  75 // turn it on so that the contents of the young list (scan-only /
  76 // to-be-collected) are printed at "strategic" points before / during
  77 // / after the collection --- this is useful for debugging
  78 #define YOUNG_LIST_VERBOSE 0
  79 // CURRENT STATUS
  80 // This file is under construction.  Search for "FIXME".
  81 
  82 // INVARIANTS/NOTES
  83 //
  84 // All allocation activity covered by the G1CollectedHeap interface is
  85 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  86 // and allocate_new_tlab, which are the "entry" points to the
  87 // allocation code from the rest of the JVM.  (Note that this does not
  88 // apply to TLAB allocation, which is not part of this interface: it
  89 // is done by clients of this interface.)
  90 
  91 // Local to this file.
  92 
  93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  94   bool _concurrent;
  95 public:
  96   RefineCardTableEntryClosure() : _concurrent(true) { }
  97 
  98   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  99     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 100     // This path is executed by the concurrent refine or mutator threads,
 101     // concurrently, and so we do not care if card_ptr contains references
 102     // that point into the collection set.
 103     assert(!oops_into_cset, "should be");
 104 
 105     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 106       // Caller will actually yield.
 107       return false;
 108     }
 109     // Otherwise, we finished successfully; return true.
 110     return true;
 111   }
 112 
 113   void set_concurrent(bool b) { _concurrent = b; }
 114 };
 115 
 116 
 117 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 118  private:
 119   size_t _num_processed;
 120 
 121  public:
 122   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 123 
 124   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 125     *card_ptr = CardTableModRefBS::dirty_card_val();
 126     _num_processed++;
 127     return true;
 128   }
 129 
 130   size_t num_processed() const { return _num_processed; }
 131 };
 132 
 133 YoungList::YoungList(G1CollectedHeap* g1h) :
 134     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 135     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 136   guarantee(check_list_empty(false), "just making sure...");
 137 }
 138 
 139 void YoungList::push_region(HeapRegion *hr) {
 140   assert(!hr->is_young(), "should not already be young");
 141   assert(hr->get_next_young_region() == NULL, "cause it should!");
 142 
 143   hr->set_next_young_region(_head);
 144   _head = hr;
 145 
 146   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 147   ++_length;
 148 }
 149 
 150 void YoungList::add_survivor_region(HeapRegion* hr) {
 151   assert(hr->is_survivor(), "should be flagged as survivor region");
 152   assert(hr->get_next_young_region() == NULL, "cause it should!");
 153 
 154   hr->set_next_young_region(_survivor_head);
 155   if (_survivor_head == NULL) {
 156     _survivor_tail = hr;
 157   }
 158   _survivor_head = hr;
 159   ++_survivor_length;
 160 }
 161 
 162 void YoungList::empty_list(HeapRegion* list) {
 163   while (list != NULL) {
 164     HeapRegion* next = list->get_next_young_region();
 165     list->set_next_young_region(NULL);
 166     list->uninstall_surv_rate_group();
 167     // This is called before a Full GC and all the non-empty /
 168     // non-humongous regions at the end of the Full GC will end up as
 169     // old anyway.
 170     list->set_old();
 171     list = next;
 172   }
 173 }
 174 
 175 void YoungList::empty_list() {
 176   assert(check_list_well_formed(), "young list should be well formed");
 177 
 178   empty_list(_head);
 179   _head = NULL;
 180   _length = 0;
 181 
 182   empty_list(_survivor_head);
 183   _survivor_head = NULL;
 184   _survivor_tail = NULL;
 185   _survivor_length = 0;
 186 
 187   _last_sampled_rs_lengths = 0;
 188 
 189   assert(check_list_empty(false), "just making sure...");
 190 }
 191 
 192 bool YoungList::check_list_well_formed() {
 193   bool ret = true;
 194 
 195   uint length = 0;
 196   HeapRegion* curr = _head;
 197   HeapRegion* last = NULL;
 198   while (curr != NULL) {
 199     if (!curr->is_young()) {
 200       gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
 201                              "incorrectly tagged (y: %d, surv: %d)",
 202                              p2i(curr->bottom()), p2i(curr->end()),
 203                              curr->is_young(), curr->is_survivor());
 204       ret = false;
 205     }
 206     ++length;
 207     last = curr;
 208     curr = curr->get_next_young_region();
 209   }
 210   ret = ret && (length == _length);
 211 
 212   if (!ret) {
 213     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 214     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 215                            length, _length);
 216   }
 217 
 218   return ret;
 219 }
 220 
 221 bool YoungList::check_list_empty(bool check_sample) {
 222   bool ret = true;
 223 
 224   if (_length != 0) {
 225     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 226                   _length);
 227     ret = false;
 228   }
 229   if (check_sample && _last_sampled_rs_lengths != 0) {
 230     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 231     ret = false;
 232   }
 233   if (_head != NULL) {
 234     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 235     ret = false;
 236   }
 237   if (!ret) {
 238     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 239   }
 240 
 241   return ret;
 242 }
 243 
 244 void
 245 YoungList::rs_length_sampling_init() {
 246   _sampled_rs_lengths = 0;
 247   _curr               = _head;
 248 }
 249 
 250 bool
 251 YoungList::rs_length_sampling_more() {
 252   return _curr != NULL;
 253 }
 254 
 255 void
 256 YoungList::rs_length_sampling_next() {
 257   assert( _curr != NULL, "invariant" );
 258   size_t rs_length = _curr->rem_set()->occupied();
 259 
 260   _sampled_rs_lengths += rs_length;
 261 
 262   // The current region may not yet have been added to the
 263   // incremental collection set (it gets added when it is
 264   // retired as the current allocation region).
 265   if (_curr->in_collection_set()) {
 266     // Update the collection set policy information for this region
 267     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 268   }
 269 
 270   _curr = _curr->get_next_young_region();
 271   if (_curr == NULL) {
 272     _last_sampled_rs_lengths = _sampled_rs_lengths;
 273     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 274   }
 275 }
 276 
 277 void
 278 YoungList::reset_auxilary_lists() {
 279   guarantee( is_empty(), "young list should be empty" );
 280   assert(check_list_well_formed(), "young list should be well formed");
 281 
 282   // Add survivor regions to SurvRateGroup.
 283   _g1h->g1_policy()->note_start_adding_survivor_regions();
 284   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 285 
 286   int young_index_in_cset = 0;
 287   for (HeapRegion* curr = _survivor_head;
 288        curr != NULL;
 289        curr = curr->get_next_young_region()) {
 290     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 291 
 292     // The region is a non-empty survivor so let's add it to
 293     // the incremental collection set for the next evacuation
 294     // pause.
 295     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 296     young_index_in_cset += 1;
 297   }
 298   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 299   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 300 
 301   _head   = _survivor_head;
 302   _length = _survivor_length;
 303   if (_survivor_head != NULL) {
 304     assert(_survivor_tail != NULL, "cause it shouldn't be");
 305     assert(_survivor_length > 0, "invariant");
 306     _survivor_tail->set_next_young_region(NULL);
 307   }
 308 
 309   // Don't clear the survivor list handles until the start of
 310   // the next evacuation pause - we need it in order to re-tag
 311   // the survivor regions from this evacuation pause as 'young'
 312   // at the start of the next.
 313 
 314   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 315 
 316   assert(check_list_well_formed(), "young list should be well formed");
 317 }
 318 
 319 void YoungList::print() {
 320   HeapRegion* lists[] = {_head,   _survivor_head};
 321   const char* names[] = {"YOUNG", "SURVIVOR"};
 322 
 323   for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
 324     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 325     HeapRegion *curr = lists[list];
 326     if (curr == NULL)
 327       gclog_or_tty->print_cr("  empty");
 328     while (curr != NULL) {
 329       gclog_or_tty->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
 330                              HR_FORMAT_PARAMS(curr),
 331                              p2i(curr->prev_top_at_mark_start()),
 332                              p2i(curr->next_top_at_mark_start()),
 333                              curr->age_in_surv_rate_group_cond());
 334       curr = curr->get_next_young_region();
 335     }
 336   }
 337 
 338   gclog_or_tty->cr();
 339 }
 340 
 341 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 342   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 343 }
 344 
 345 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 346   // The from card cache is not the memory that is actually committed. So we cannot
 347   // take advantage of the zero_filled parameter.
 348   reset_from_card_cache(start_idx, num_regions);
 349 }
 350 
 351 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 352 {
 353   // Claim the right to put the region on the dirty cards region list
 354   // by installing a self pointer.
 355   HeapRegion* next = hr->get_next_dirty_cards_region();
 356   if (next == NULL) {
 357     HeapRegion* res = (HeapRegion*)
 358       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 359                           NULL);
 360     if (res == NULL) {
 361       HeapRegion* head;
 362       do {
 363         // Put the region to the dirty cards region list.
 364         head = _dirty_cards_region_list;
 365         next = (HeapRegion*)
 366           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 367         if (next == head) {
 368           assert(hr->get_next_dirty_cards_region() == hr,
 369                  "hr->get_next_dirty_cards_region() != hr");
 370           if (next == NULL) {
 371             // The last region in the list points to itself.
 372             hr->set_next_dirty_cards_region(hr);
 373           } else {
 374             hr->set_next_dirty_cards_region(next);
 375           }
 376         }
 377       } while (next != head);
 378     }
 379   }
 380 }
 381 
 382 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 383 {
 384   HeapRegion* head;
 385   HeapRegion* hr;
 386   do {
 387     head = _dirty_cards_region_list;
 388     if (head == NULL) {
 389       return NULL;
 390     }
 391     HeapRegion* new_head = head->get_next_dirty_cards_region();
 392     if (head == new_head) {
 393       // The last region.
 394       new_head = NULL;
 395     }
 396     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 397                                           head);
 398   } while (hr != head);
 399   assert(hr != NULL, "invariant");
 400   hr->set_next_dirty_cards_region(NULL);
 401   return hr;
 402 }
 403 
 404 // Returns true if the reference points to an object that
 405 // can move in an incremental collection.
 406 bool G1CollectedHeap::is_scavengable(const void* p) {
 407   HeapRegion* hr = heap_region_containing(p);
 408   return !hr->is_pinned();
 409 }
 410 
 411 // Private methods.
 412 
 413 HeapRegion*
 414 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 415   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 416   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 417     if (!_secondary_free_list.is_empty()) {
 418       if (G1ConcRegionFreeingVerbose) {
 419         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 420                                "secondary_free_list has %u entries",
 421                                _secondary_free_list.length());
 422       }
 423       // It looks as if there are free regions available on the
 424       // secondary_free_list. Let's move them to the free_list and try
 425       // again to allocate from it.
 426       append_secondary_free_list();
 427 
 428       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 429              "empty we should have moved at least one entry to the free_list");
 430       HeapRegion* res = _hrm.allocate_free_region(is_old);
 431       if (G1ConcRegionFreeingVerbose) {
 432         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 433                                "allocated " HR_FORMAT " from secondary_free_list",
 434                                HR_FORMAT_PARAMS(res));
 435       }
 436       return res;
 437     }
 438 
 439     // Wait here until we get notified either when (a) there are no
 440     // more free regions coming or (b) some regions have been moved on
 441     // the secondary_free_list.
 442     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 443   }
 444 
 445   if (G1ConcRegionFreeingVerbose) {
 446     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 447                            "could not allocate from secondary_free_list");
 448   }
 449   return NULL;
 450 }
 451 
 452 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 453   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 454          "the only time we use this to allocate a humongous region is "
 455          "when we are allocating a single humongous region");
 456 
 457   HeapRegion* res;
 458   if (G1StressConcRegionFreeing) {
 459     if (!_secondary_free_list.is_empty()) {
 460       if (G1ConcRegionFreeingVerbose) {
 461         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 462                                "forced to look at the secondary_free_list");
 463       }
 464       res = new_region_try_secondary_free_list(is_old);
 465       if (res != NULL) {
 466         return res;
 467       }
 468     }
 469   }
 470 
 471   res = _hrm.allocate_free_region(is_old);
 472 
 473   if (res == NULL) {
 474     if (G1ConcRegionFreeingVerbose) {
 475       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 476                              "res == NULL, trying the secondary_free_list");
 477     }
 478     res = new_region_try_secondary_free_list(is_old);
 479   }
 480   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 481     // Currently, only attempts to allocate GC alloc regions set
 482     // do_expand to true. So, we should only reach here during a
 483     // safepoint. If this assumption changes we might have to
 484     // reconsider the use of _expand_heap_after_alloc_failure.
 485     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 486 
 487     ergo_verbose1(ErgoHeapSizing,
 488                   "attempt heap expansion",
 489                   ergo_format_reason("region allocation request failed")
 490                   ergo_format_byte("allocation request"),
 491                   word_size * HeapWordSize);
 492     if (expand(word_size * HeapWordSize)) {
 493       // Given that expand() succeeded in expanding the heap, and we
 494       // always expand the heap by an amount aligned to the heap
 495       // region size, the free list should in theory not be empty.
 496       // In either case allocate_free_region() will check for NULL.
 497       res = _hrm.allocate_free_region(is_old);
 498     } else {
 499       _expand_heap_after_alloc_failure = false;
 500     }
 501   }
 502   return res;
 503 }
 504 
 505 HeapWord*
 506 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 507                                                            uint num_regions,
 508                                                            size_t word_size,
 509                                                            AllocationContext_t context) {
 510   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 511   assert(is_humongous(word_size), "word_size should be humongous");
 512   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 513 
 514   // Index of last region in the series + 1.
 515   uint last = first + num_regions;
 516 
 517   // We need to initialize the region(s) we just discovered. This is
 518   // a bit tricky given that it can happen concurrently with
 519   // refinement threads refining cards on these regions and
 520   // potentially wanting to refine the BOT as they are scanning
 521   // those cards (this can happen shortly after a cleanup; see CR
 522   // 6991377). So we have to set up the region(s) carefully and in
 523   // a specific order.
 524 
 525   // The word size sum of all the regions we will allocate.
 526   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 527   assert(word_size <= word_size_sum, "sanity");
 528 
 529   // This will be the "starts humongous" region.
 530   HeapRegion* first_hr = region_at(first);
 531   // The header of the new object will be placed at the bottom of
 532   // the first region.
 533   HeapWord* new_obj = first_hr->bottom();
 534   // This will be the new end of the first region in the series that
 535   // should also match the end of the last region in the series.
 536   HeapWord* new_end = new_obj + word_size_sum;
 537   // This will be the new top of the first region that will reflect
 538   // this allocation.
 539   HeapWord* new_top = new_obj + word_size;
 540 
 541   // First, we need to zero the header of the space that we will be
 542   // allocating. When we update top further down, some refinement
 543   // threads might try to scan the region. By zeroing the header we
 544   // ensure that any thread that will try to scan the region will
 545   // come across the zero klass word and bail out.
 546   //
 547   // NOTE: It would not have been correct to have used
 548   // CollectedHeap::fill_with_object() and make the space look like
 549   // an int array. The thread that is doing the allocation will
 550   // later update the object header to a potentially different array
 551   // type and, for a very short period of time, the klass and length
 552   // fields will be inconsistent. This could cause a refinement
 553   // thread to calculate the object size incorrectly.
 554   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 555 
 556   // We will set up the first region as "starts humongous". This
 557   // will also update the BOT covering all the regions to reflect
 558   // that there is a single object that starts at the bottom of the
 559   // first region.
 560   first_hr->set_starts_humongous(new_top, new_end);
 561   first_hr->set_allocation_context(context);
 562   // Then, if there are any, we will set up the "continues
 563   // humongous" regions.
 564   HeapRegion* hr = NULL;
 565   for (uint i = first + 1; i < last; ++i) {
 566     hr = region_at(i);
 567     hr->set_continues_humongous(first_hr);
 568     hr->set_allocation_context(context);
 569   }
 570   // If we have "continues humongous" regions (hr != NULL), then the
 571   // end of the last one should match new_end.
 572   assert(hr == NULL || hr->end() == new_end, "sanity");
 573 
 574   // Up to this point no concurrent thread would have been able to
 575   // do any scanning on any region in this series. All the top
 576   // fields still point to bottom, so the intersection between
 577   // [bottom,top] and [card_start,card_end] will be empty. Before we
 578   // update the top fields, we'll do a storestore to make sure that
 579   // no thread sees the update to top before the zeroing of the
 580   // object header and the BOT initialization.
 581   OrderAccess::storestore();
 582 
 583   // Now that the BOT and the object header have been initialized,
 584   // we can update top of the "starts humongous" region.
 585   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 586          "new_top should be in this region");
 587   first_hr->set_top(new_top);
 588   if (_hr_printer.is_active()) {
 589     HeapWord* bottom = first_hr->bottom();
 590     HeapWord* end = first_hr->orig_end();
 591     if ((first + 1) == last) {
 592       // the series has a single humongous region
 593       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 594     } else {
 595       // the series has more than one humongous regions
 596       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 597     }
 598   }
 599 
 600   // Now, we will update the top fields of the "continues humongous"
 601   // regions. The reason we need to do this is that, otherwise,
 602   // these regions would look empty and this will confuse parts of
 603   // G1. For example, the code that looks for a consecutive number
 604   // of empty regions will consider them empty and try to
 605   // re-allocate them. We can extend is_empty() to also include
 606   // !is_continues_humongous(), but it is easier to just update the top
 607   // fields here. The way we set top for all regions (i.e., top ==
 608   // end for all regions but the last one, top == new_top for the
 609   // last one) is actually used when we will free up the humongous
 610   // region in free_humongous_region().
 611   hr = NULL;
 612   for (uint i = first + 1; i < last; ++i) {
 613     hr = region_at(i);
 614     if ((i + 1) == last) {
 615       // last continues humongous region
 616       assert(hr->bottom() < new_top && new_top <= hr->end(),
 617              "new_top should fall on this region");
 618       hr->set_top(new_top);
 619       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 620     } else {
 621       // not last one
 622       assert(new_top > hr->end(), "new_top should be above this region");
 623       hr->set_top(hr->end());
 624       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 625     }
 626   }
 627   // If we have continues humongous regions (hr != NULL), then the
 628   // end of the last one should match new_end and its top should
 629   // match new_top.
 630   assert(hr == NULL ||
 631          (hr->end() == new_end && hr->top() == new_top), "sanity");
 632   check_bitmaps("Humongous Region Allocation", first_hr);
 633 
 634   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 635   increase_used(first_hr->used());
 636   _humongous_set.add(first_hr);
 637 
 638   return new_obj;
 639 }
 640 
 641 // If could fit into free regions w/o expansion, try.
 642 // Otherwise, if can expand, do so.
 643 // Otherwise, if using ex regions might help, try with ex given back.
 644 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 645   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 646 
 647   verify_region_sets_optional();
 648 
 649   uint first = G1_NO_HRM_INDEX;
 650   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 651 
 652   if (obj_regions == 1) {
 653     // Only one region to allocate, try to use a fast path by directly allocating
 654     // from the free lists. Do not try to expand here, we will potentially do that
 655     // later.
 656     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 657     if (hr != NULL) {
 658       first = hr->hrm_index();
 659     }
 660   } else {
 661     // We can't allocate humongous regions spanning more than one region while
 662     // cleanupComplete() is running, since some of the regions we find to be
 663     // empty might not yet be added to the free list. It is not straightforward
 664     // to know in which list they are on so that we can remove them. We only
 665     // need to do this if we need to allocate more than one region to satisfy the
 666     // current humongous allocation request. If we are only allocating one region
 667     // we use the one-region region allocation code (see above), that already
 668     // potentially waits for regions from the secondary free list.
 669     wait_while_free_regions_coming();
 670     append_secondary_free_list_if_not_empty_with_lock();
 671 
 672     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 673     // are lucky enough to find some.
 674     first = _hrm.find_contiguous_only_empty(obj_regions);
 675     if (first != G1_NO_HRM_INDEX) {
 676       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 677     }
 678   }
 679 
 680   if (first == G1_NO_HRM_INDEX) {
 681     // Policy: We could not find enough regions for the humongous object in the
 682     // free list. Look through the heap to find a mix of free and uncommitted regions.
 683     // If so, try expansion.
 684     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 685     if (first != G1_NO_HRM_INDEX) {
 686       // We found something. Make sure these regions are committed, i.e. expand
 687       // the heap. Alternatively we could do a defragmentation GC.
 688       ergo_verbose1(ErgoHeapSizing,
 689                     "attempt heap expansion",
 690                     ergo_format_reason("humongous allocation request failed")
 691                     ergo_format_byte("allocation request"),
 692                     word_size * HeapWordSize);
 693 
 694       _hrm.expand_at(first, obj_regions);
 695       g1_policy()->record_new_heap_size(num_regions());
 696 
 697 #ifdef ASSERT
 698       for (uint i = first; i < first + obj_regions; ++i) {
 699         HeapRegion* hr = region_at(i);
 700         assert(hr->is_free(), "sanity");
 701         assert(hr->is_empty(), "sanity");
 702         assert(is_on_master_free_list(hr), "sanity");
 703       }
 704 #endif
 705       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 706     } else {
 707       // Policy: Potentially trigger a defragmentation GC.
 708     }
 709   }
 710 
 711   HeapWord* result = NULL;
 712   if (first != G1_NO_HRM_INDEX) {
 713     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 714                                                        word_size, context);
 715     assert(result != NULL, "it should always return a valid result");
 716 
 717     // A successful humongous object allocation changes the used space
 718     // information of the old generation so we need to recalculate the
 719     // sizes and update the jstat counters here.
 720     g1mm()->update_sizes();
 721   }
 722 
 723   verify_region_sets_optional();
 724 
 725   return result;
 726 }
 727 
 728 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 729   assert_heap_not_locked_and_not_at_safepoint();
 730   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 731 
 732   uint dummy_gc_count_before;
 733   uint dummy_gclocker_retry_count = 0;
 734   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 735 }
 736 
 737 HeapWord*
 738 G1CollectedHeap::mem_allocate(size_t word_size,
 739                               bool*  gc_overhead_limit_was_exceeded) {
 740   assert_heap_not_locked_and_not_at_safepoint();
 741 
 742   // Loop until the allocation is satisfied, or unsatisfied after GC.
 743   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 744     uint gc_count_before;
 745 
 746     HeapWord* result = NULL;
 747     if (!is_humongous(word_size)) {
 748       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 749     } else {
 750       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 751     }
 752     if (result != NULL) {
 753       return result;
 754     }
 755 
 756     // Create the garbage collection operation...
 757     VM_G1CollectForAllocation op(gc_count_before, word_size);
 758     op.set_allocation_context(AllocationContext::current());
 759 
 760     // ...and get the VM thread to execute it.
 761     VMThread::execute(&op);
 762 
 763     if (op.prologue_succeeded() && op.pause_succeeded()) {
 764       // If the operation was successful we'll return the result even
 765       // if it is NULL. If the allocation attempt failed immediately
 766       // after a Full GC, it's unlikely we'll be able to allocate now.
 767       HeapWord* result = op.result();
 768       if (result != NULL && !is_humongous(word_size)) {
 769         // Allocations that take place on VM operations do not do any
 770         // card dirtying and we have to do it here. We only have to do
 771         // this for non-humongous allocations, though.
 772         dirty_young_block(result, word_size);
 773       }
 774       return result;
 775     } else {
 776       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 777         return NULL;
 778       }
 779       assert(op.result() == NULL,
 780              "the result should be NULL if the VM op did not succeed");
 781     }
 782 
 783     // Give a warning if we seem to be looping forever.
 784     if ((QueuedAllocationWarningCount > 0) &&
 785         (try_count % QueuedAllocationWarningCount == 0)) {
 786       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 787     }
 788   }
 789 
 790   ShouldNotReachHere();
 791   return NULL;
 792 }
 793 
 794 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 795                                                    AllocationContext_t context,
 796                                                    uint* gc_count_before_ret,
 797                                                    uint* gclocker_retry_count_ret) {
 798   // Make sure you read the note in attempt_allocation_humongous().
 799 
 800   assert_heap_not_locked_and_not_at_safepoint();
 801   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 802          "be called for humongous allocation requests");
 803 
 804   // We should only get here after the first-level allocation attempt
 805   // (attempt_allocation()) failed to allocate.
 806 
 807   // We will loop until a) we manage to successfully perform the
 808   // allocation or b) we successfully schedule a collection which
 809   // fails to perform the allocation. b) is the only case when we'll
 810   // return NULL.
 811   HeapWord* result = NULL;
 812   for (int try_count = 1; /* we'll return */; try_count += 1) {
 813     bool should_try_gc;
 814     uint gc_count_before;
 815 
 816     {
 817       MutexLockerEx x(Heap_lock);
 818       result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
 819                                                                                     false /* bot_updates */);
 820       if (result != NULL) {
 821         return result;
 822       }
 823 
 824       // If we reach here, attempt_allocation_locked() above failed to
 825       // allocate a new region. So the mutator alloc region should be NULL.
 826       assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
 827 
 828       if (GC_locker::is_active_and_needs_gc()) {
 829         if (g1_policy()->can_expand_young_list()) {
 830           // No need for an ergo verbose message here,
 831           // can_expand_young_list() does this when it returns true.
 832           result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
 833                                                                                        false /* bot_updates */);
 834           if (result != NULL) {
 835             return result;
 836           }
 837         }
 838         should_try_gc = false;
 839       } else {
 840         // The GCLocker may not be active but the GCLocker initiated
 841         // GC may not yet have been performed (GCLocker::needs_gc()
 842         // returns true). In this case we do not try this GC and
 843         // wait until the GCLocker initiated GC is performed, and
 844         // then retry the allocation.
 845         if (GC_locker::needs_gc()) {
 846           should_try_gc = false;
 847         } else {
 848           // Read the GC count while still holding the Heap_lock.
 849           gc_count_before = total_collections();
 850           should_try_gc = true;
 851         }
 852       }
 853     }
 854 
 855     if (should_try_gc) {
 856       bool succeeded;
 857       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 858                                    GCCause::_g1_inc_collection_pause);
 859       if (result != NULL) {
 860         assert(succeeded, "only way to get back a non-NULL result");
 861         return result;
 862       }
 863 
 864       if (succeeded) {
 865         // If we get here we successfully scheduled a collection which
 866         // failed to allocate. No point in trying to allocate
 867         // further. We'll just return NULL.
 868         MutexLockerEx x(Heap_lock);
 869         *gc_count_before_ret = total_collections();
 870         return NULL;
 871       }
 872     } else {
 873       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 874         MutexLockerEx x(Heap_lock);
 875         *gc_count_before_ret = total_collections();
 876         return NULL;
 877       }
 878       // The GCLocker is either active or the GCLocker initiated
 879       // GC has not yet been performed. Stall until it is and
 880       // then retry the allocation.
 881       GC_locker::stall_until_clear();
 882       (*gclocker_retry_count_ret) += 1;
 883     }
 884 
 885     // We can reach here if we were unsuccessful in scheduling a
 886     // collection (because another thread beat us to it) or if we were
 887     // stalled due to the GC locker. In either can we should retry the
 888     // allocation attempt in case another thread successfully
 889     // performed a collection and reclaimed enough space. We do the
 890     // first attempt (without holding the Heap_lock) here and the
 891     // follow-on attempt will be at the start of the next loop
 892     // iteration (after taking the Heap_lock).
 893     result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
 894                                                                            false /* bot_updates */);
 895     if (result != NULL) {
 896       return result;
 897     }
 898 
 899     // Give a warning if we seem to be looping forever.
 900     if ((QueuedAllocationWarningCount > 0) &&
 901         (try_count % QueuedAllocationWarningCount == 0)) {
 902       warning("G1CollectedHeap::attempt_allocation_slow() "
 903               "retries %d times", try_count);
 904     }
 905   }
 906 
 907   ShouldNotReachHere();
 908   return NULL;
 909 }
 910 
 911 void G1CollectedHeap::begin_archive_alloc_range() {
 912   assert_at_safepoint(true /* should_be_vm_thread */);
 913   if (_archive_allocator == NULL) {
 914     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 915   }
 916 }
 917 
 918 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 919   // Allocations in archive regions cannot be of a size that would be considered
 920   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 921   // may be different at archive-restore time.
 922   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 923 }
 924 
 925 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 926   assert_at_safepoint(true /* should_be_vm_thread */);
 927   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 928   if (is_archive_alloc_too_large(word_size)) {
 929     return NULL;
 930   }
 931   return _archive_allocator->archive_mem_allocate(word_size);
 932 }
 933 
 934 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 935                                               size_t end_alignment_in_bytes) {
 936   assert_at_safepoint(true /* should_be_vm_thread */);
 937   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 938 
 939   // Call complete_archive to do the real work, filling in the MemRegion
 940   // array with the archive regions.
 941   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 942   delete _archive_allocator;
 943   _archive_allocator = NULL;
 944 }
 945 
 946 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 947   assert(ranges != NULL, "MemRegion array NULL");
 948   assert(count != 0, "No MemRegions provided");
 949   MemRegion reserved = _hrm.reserved();
 950   for (size_t i = 0; i < count; i++) {
 951     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 952       return false;
 953     }
 954   }
 955   return true;
 956 }
 957 
 958 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 959   assert(ranges != NULL, "MemRegion array NULL");
 960   assert(count != 0, "No MemRegions provided");
 961   MutexLockerEx x(Heap_lock);
 962 
 963   MemRegion reserved = _hrm.reserved();
 964   HeapWord* prev_last_addr = NULL;
 965   HeapRegion* prev_last_region = NULL;
 966 
 967   // Temporarily disable pretouching of heap pages. This interface is used
 968   // when mmap'ing archived heap data in, so pre-touching is wasted.
 969   FlagSetting fs(AlwaysPreTouch, false);
 970 
 971   // Enable archive object checking in G1MarkSweep. We have to let it know
 972   // about each archive range, so that objects in those ranges aren't marked.
 973   G1MarkSweep::enable_archive_object_check();
 974 
 975   // For each specified MemRegion range, allocate the corresponding G1
 976   // regions and mark them as archive regions. We expect the ranges in
 977   // ascending starting address order, without overlap.
 978   for (size_t i = 0; i < count; i++) {
 979     MemRegion curr_range = ranges[i];
 980     HeapWord* start_address = curr_range.start();
 981     size_t word_size = curr_range.word_size();
 982     HeapWord* last_address = curr_range.last();
 983     size_t commits = 0;
 984 
 985     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 986               err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 987               p2i(start_address), p2i(last_address)));
 988     guarantee(start_address > prev_last_addr,
 989               err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 990               p2i(start_address), p2i(prev_last_addr)));
 991     prev_last_addr = last_address;
 992 
 993     // Check for ranges that start in the same G1 region in which the previous
 994     // range ended, and adjust the start address so we don't try to allocate
 995     // the same region again. If the current range is entirely within that
 996     // region, skip it, just adjusting the recorded top.
 997     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 998     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 999       start_address = start_region->end();
1000       if (start_address > last_address) {
1001         increase_used(word_size * HeapWordSize);
1002         start_region->set_top(last_address + 1);
1003         continue;
1004       }
1005       start_region->set_top(start_address);
1006       curr_range = MemRegion(start_address, last_address + 1);
1007       start_region = _hrm.addr_to_region(start_address);
1008     }
1009 
1010     // Perform the actual region allocation, exiting if it fails.
1011     // Then note how much new space we have allocated.
1012     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1013       return false;
1014     }
1015     increase_used(word_size * HeapWordSize);
1016     if (commits != 0) {
1017       ergo_verbose1(ErgoHeapSizing,
1018                     "attempt heap expansion",
1019                     ergo_format_reason("allocate archive regions")
1020                     ergo_format_byte("total size"),
1021                     HeapRegion::GrainWords * HeapWordSize * commits);
1022     }
1023 
1024     // Mark each G1 region touched by the range as archive, add it to the old set,
1025     // and set the allocation context and top.
1026     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1027     HeapRegion* last_region = _hrm.addr_to_region(last_address);
1028     prev_last_region = last_region;
1029 
1030     while (curr_region != NULL) {
1031       assert(curr_region->is_empty() && !curr_region->is_pinned(),
1032              err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1033       _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1034       curr_region->set_allocation_context(AllocationContext::system());
1035       curr_region->set_archive();
1036       _old_set.add(curr_region);
1037       if (curr_region != last_region) {
1038         curr_region->set_top(curr_region->end());
1039         curr_region = _hrm.next_region_in_heap(curr_region);
1040       } else {
1041         curr_region->set_top(last_address + 1);
1042         curr_region = NULL;
1043       }
1044     }
1045 
1046     // Notify mark-sweep of the archive range.
1047     G1MarkSweep::mark_range_archive(curr_range);
1048   }
1049   return true;
1050 }
1051 
1052 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1053   assert(ranges != NULL, "MemRegion array NULL");
1054   assert(count != 0, "No MemRegions provided");
1055   MemRegion reserved = _hrm.reserved();
1056   HeapWord *prev_last_addr = NULL;
1057   HeapRegion* prev_last_region = NULL;
1058 
1059   // For each MemRegion, create filler objects, if needed, in the G1 regions
1060   // that contain the address range. The address range actually within the
1061   // MemRegion will not be modified. That is assumed to have been initialized
1062   // elsewhere, probably via an mmap of archived heap data.
1063   MutexLockerEx x(Heap_lock);
1064   for (size_t i = 0; i < count; i++) {
1065     HeapWord* start_address = ranges[i].start();
1066     HeapWord* last_address = ranges[i].last();
1067 
1068     assert(reserved.contains(start_address) && reserved.contains(last_address),
1069            err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1070                    p2i(start_address), p2i(last_address)));
1071     assert(start_address > prev_last_addr,
1072            err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1073                    p2i(start_address), p2i(prev_last_addr)));
1074 
1075     HeapRegion* start_region = _hrm.addr_to_region(start_address);
1076     HeapRegion* last_region = _hrm.addr_to_region(last_address);
1077     HeapWord* bottom_address = start_region->bottom();
1078 
1079     // Check for a range beginning in the same region in which the
1080     // previous one ended.
1081     if (start_region == prev_last_region) {
1082       bottom_address = prev_last_addr + 1;
1083     }
1084 
1085     // Verify that the regions were all marked as archive regions by
1086     // alloc_archive_regions.
1087     HeapRegion* curr_region = start_region;
1088     while (curr_region != NULL) {
1089       guarantee(curr_region->is_archive(),
1090                 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1091       if (curr_region != last_region) {
1092         curr_region = _hrm.next_region_in_heap(curr_region);
1093       } else {
1094         curr_region = NULL;
1095       }
1096     }
1097 
1098     prev_last_addr = last_address;
1099     prev_last_region = last_region;
1100 
1101     // Fill the memory below the allocated range with dummy object(s),
1102     // if the region bottom does not match the range start, or if the previous
1103     // range ended within the same G1 region, and there is a gap.
1104     if (start_address != bottom_address) {
1105       size_t fill_size = pointer_delta(start_address, bottom_address);
1106       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1107       increase_used(fill_size * HeapWordSize);
1108     }
1109   }
1110 }
1111 
1112 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1113                                                         uint* gc_count_before_ret,
1114                                                         uint* gclocker_retry_count_ret) {
1115   // The structure of this method has a lot of similarities to
1116   // attempt_allocation_slow(). The reason these two were not merged
1117   // into a single one is that such a method would require several "if
1118   // allocation is not humongous do this, otherwise do that"
1119   // conditional paths which would obscure its flow. In fact, an early
1120   // version of this code did use a unified method which was harder to
1121   // follow and, as a result, it had subtle bugs that were hard to
1122   // track down. So keeping these two methods separate allows each to
1123   // be more readable. It will be good to keep these two in sync as
1124   // much as possible.
1125 
1126   assert_heap_not_locked_and_not_at_safepoint();
1127   assert(is_humongous(word_size), "attempt_allocation_humongous() "
1128          "should only be called for humongous allocations");
1129 
1130   // Humongous objects can exhaust the heap quickly, so we should check if we
1131   // need to start a marking cycle at each humongous object allocation. We do
1132   // the check before we do the actual allocation. The reason for doing it
1133   // before the allocation is that we avoid having to keep track of the newly
1134   // allocated memory while we do a GC.
1135   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1136                                            word_size)) {
1137     collect(GCCause::_g1_humongous_allocation);
1138   }
1139 
1140   // We will loop until a) we manage to successfully perform the
1141   // allocation or b) we successfully schedule a collection which
1142   // fails to perform the allocation. b) is the only case when we'll
1143   // return NULL.
1144   HeapWord* result = NULL;
1145   for (int try_count = 1; /* we'll return */; try_count += 1) {
1146     bool should_try_gc;
1147     uint gc_count_before;
1148 
1149     {
1150       MutexLockerEx x(Heap_lock);
1151 
1152       // Given that humongous objects are not allocated in young
1153       // regions, we'll first try to do the allocation without doing a
1154       // collection hoping that there's enough space in the heap.
1155       result = humongous_obj_allocate(word_size, AllocationContext::current());
1156       if (result != NULL) {
1157         return result;
1158       }
1159 
1160       if (GC_locker::is_active_and_needs_gc()) {
1161         should_try_gc = false;
1162       } else {
1163          // The GCLocker may not be active but the GCLocker initiated
1164         // GC may not yet have been performed (GCLocker::needs_gc()
1165         // returns true). In this case we do not try this GC and
1166         // wait until the GCLocker initiated GC is performed, and
1167         // then retry the allocation.
1168         if (GC_locker::needs_gc()) {
1169           should_try_gc = false;
1170         } else {
1171           // Read the GC count while still holding the Heap_lock.
1172           gc_count_before = total_collections();
1173           should_try_gc = true;
1174         }
1175       }
1176     }
1177 
1178     if (should_try_gc) {
1179       // If we failed to allocate the humongous object, we should try to
1180       // do a collection pause (if we're allowed) in case it reclaims
1181       // enough space for the allocation to succeed after the pause.
1182 
1183       bool succeeded;
1184       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1185                                    GCCause::_g1_humongous_allocation);
1186       if (result != NULL) {
1187         assert(succeeded, "only way to get back a non-NULL result");
1188         return result;
1189       }
1190 
1191       if (succeeded) {
1192         // If we get here we successfully scheduled a collection which
1193         // failed to allocate. No point in trying to allocate
1194         // further. We'll just return NULL.
1195         MutexLockerEx x(Heap_lock);
1196         *gc_count_before_ret = total_collections();
1197         return NULL;
1198       }
1199     } else {
1200       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1201         MutexLockerEx x(Heap_lock);
1202         *gc_count_before_ret = total_collections();
1203         return NULL;
1204       }
1205       // The GCLocker is either active or the GCLocker initiated
1206       // GC has not yet been performed. Stall until it is and
1207       // then retry the allocation.
1208       GC_locker::stall_until_clear();
1209       (*gclocker_retry_count_ret) += 1;
1210     }
1211 
1212     // We can reach here if we were unsuccessful in scheduling a
1213     // collection (because another thread beat us to it) or if we were
1214     // stalled due to the GC locker. In either can we should retry the
1215     // allocation attempt in case another thread successfully
1216     // performed a collection and reclaimed enough space.  Give a
1217     // warning if we seem to be looping forever.
1218 
1219     if ((QueuedAllocationWarningCount > 0) &&
1220         (try_count % QueuedAllocationWarningCount == 0)) {
1221       warning("G1CollectedHeap::attempt_allocation_humongous() "
1222               "retries %d times", try_count);
1223     }
1224   }
1225 
1226   ShouldNotReachHere();
1227   return NULL;
1228 }
1229 
1230 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1231                                                            AllocationContext_t context,
1232                                                            bool expect_null_mutator_alloc_region) {
1233   assert_at_safepoint(true /* should_be_vm_thread */);
1234   assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1235                                              !expect_null_mutator_alloc_region,
1236          "the current alloc region was unexpectedly found to be non-NULL");
1237 
1238   if (!is_humongous(word_size)) {
1239     return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1240                                                       false /* bot_updates */);
1241   } else {
1242     HeapWord* result = humongous_obj_allocate(word_size, context);
1243     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1244       collector_state()->set_initiate_conc_mark_if_possible(true);
1245     }
1246     return result;
1247   }
1248 
1249   ShouldNotReachHere();
1250 }
1251 
1252 class PostMCRemSetClearClosure: public HeapRegionClosure {
1253   G1CollectedHeap* _g1h;
1254   ModRefBarrierSet* _mr_bs;
1255 public:
1256   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1257     _g1h(g1h), _mr_bs(mr_bs) {}
1258 
1259   bool doHeapRegion(HeapRegion* r) {
1260     HeapRegionRemSet* hrrs = r->rem_set();
1261 
1262     if (r->is_continues_humongous()) {
1263       // We'll assert that the strong code root list and RSet is empty
1264       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1265       assert(hrrs->occupied() == 0, "RSet should be empty");
1266       return false;
1267     }
1268 
1269     _g1h->reset_gc_time_stamps(r);
1270     hrrs->clear();
1271     // You might think here that we could clear just the cards
1272     // corresponding to the used region.  But no: if we leave a dirty card
1273     // in a region we might allocate into, then it would prevent that card
1274     // from being enqueued, and cause it to be missed.
1275     // Re: the performance cost: we shouldn't be doing full GC anyway!
1276     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1277 
1278     return false;
1279   }
1280 };
1281 
1282 void G1CollectedHeap::clear_rsets_post_compaction() {
1283   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1284   heap_region_iterate(&rs_clear);
1285 }
1286 
1287 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1288   G1CollectedHeap*   _g1h;
1289   UpdateRSOopClosure _cl;
1290 public:
1291   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1292     _cl(g1->g1_rem_set(), worker_i),
1293     _g1h(g1)
1294   { }
1295 
1296   bool doHeapRegion(HeapRegion* r) {
1297     if (!r->is_continues_humongous()) {
1298       _cl.set_from(r);
1299       r->oop_iterate(&_cl);
1300     }
1301     return false;
1302   }
1303 };
1304 
1305 class ParRebuildRSTask: public AbstractGangTask {
1306   G1CollectedHeap* _g1;
1307   HeapRegionClaimer _hrclaimer;
1308 
1309 public:
1310   ParRebuildRSTask(G1CollectedHeap* g1) :
1311       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1312 
1313   void work(uint worker_id) {
1314     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1315     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1316   }
1317 };
1318 
1319 class PostCompactionPrinterClosure: public HeapRegionClosure {
1320 private:
1321   G1HRPrinter* _hr_printer;
1322 public:
1323   bool doHeapRegion(HeapRegion* hr) {
1324     assert(!hr->is_young(), "not expecting to find young regions");
1325     if (hr->is_free()) {
1326       // We only generate output for non-empty regions.
1327     } else if (hr->is_starts_humongous()) {
1328       if (hr->region_num() == 1) {
1329         // single humongous region
1330         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1331       } else {
1332         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1333       }
1334     } else if (hr->is_continues_humongous()) {
1335       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1336     } else if (hr->is_archive()) {
1337       _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1338     } else if (hr->is_old()) {
1339       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1340     } else {
1341       ShouldNotReachHere();
1342     }
1343     return false;
1344   }
1345 
1346   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1347     : _hr_printer(hr_printer) { }
1348 };
1349 
1350 void G1CollectedHeap::print_hrm_post_compaction() {
1351   PostCompactionPrinterClosure cl(hr_printer());
1352   heap_region_iterate(&cl);
1353 }
1354 
1355 bool G1CollectedHeap::do_collection(bool explicit_gc,
1356                                     bool clear_all_soft_refs,
1357                                     size_t word_size) {
1358   assert_at_safepoint(true /* should_be_vm_thread */);
1359 
1360   if (GC_locker::check_active_before_gc()) {
1361     return false;
1362   }
1363 
1364   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1365   gc_timer->register_gc_start();
1366 
1367   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1368   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1369 
1370   SvcGCMarker sgcm(SvcGCMarker::FULL);
1371   ResourceMark rm;
1372 
1373   G1Log::update_level();
1374   print_heap_before_gc();
1375   trace_heap_before_gc(gc_tracer);
1376 
1377   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1378 
1379   verify_region_sets_optional();
1380 
1381   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1382                            collector_policy()->should_clear_all_soft_refs();
1383 
1384   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1385 
1386   {
1387     IsGCActiveMark x;
1388 
1389     // Timing
1390     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1391     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1392 
1393     {
1394       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1395       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1396       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1397 
1398       g1_policy()->record_full_collection_start();
1399 
1400       // Note: When we have a more flexible GC logging framework that
1401       // allows us to add optional attributes to a GC log record we
1402       // could consider timing and reporting how long we wait in the
1403       // following two methods.
1404       wait_while_free_regions_coming();
1405       // If we start the compaction before the CM threads finish
1406       // scanning the root regions we might trip them over as we'll
1407       // be moving objects / updating references. So let's wait until
1408       // they are done. By telling them to abort, they should complete
1409       // early.
1410       _cm->root_regions()->abort();
1411       _cm->root_regions()->wait_until_scan_finished();
1412       append_secondary_free_list_if_not_empty_with_lock();
1413 
1414       gc_prologue(true);
1415       increment_total_collections(true /* full gc */);
1416       increment_old_marking_cycles_started();
1417 
1418       assert(used() == recalculate_used(), "Should be equal");
1419 
1420       verify_before_gc();
1421 
1422       check_bitmaps("Full GC Start");
1423       pre_full_gc_dump(gc_timer);
1424 
1425       COMPILER2_PRESENT(DerivedPointerTable::clear());
1426 
1427       // Disable discovery and empty the discovered lists
1428       // for the CM ref processor.
1429       ref_processor_cm()->disable_discovery();
1430       ref_processor_cm()->abandon_partial_discovery();
1431       ref_processor_cm()->verify_no_references_recorded();
1432 
1433       // Abandon current iterations of concurrent marking and concurrent
1434       // refinement, if any are in progress. We have to do this before
1435       // wait_until_scan_finished() below.
1436       concurrent_mark()->abort();
1437 
1438       // Make sure we'll choose a new allocation region afterwards.
1439       _allocator->release_mutator_alloc_region();
1440       _allocator->abandon_gc_alloc_regions();
1441       g1_rem_set()->cleanupHRRS();
1442 
1443       // We should call this after we retire any currently active alloc
1444       // regions so that all the ALLOC / RETIRE events are generated
1445       // before the start GC event.
1446       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1447 
1448       // We may have added regions to the current incremental collection
1449       // set between the last GC or pause and now. We need to clear the
1450       // incremental collection set and then start rebuilding it afresh
1451       // after this full GC.
1452       abandon_collection_set(g1_policy()->inc_cset_head());
1453       g1_policy()->clear_incremental_cset();
1454       g1_policy()->stop_incremental_cset_building();
1455 
1456       tear_down_region_sets(false /* free_list_only */);
1457       collector_state()->set_gcs_are_young(true);
1458 
1459       // See the comments in g1CollectedHeap.hpp and
1460       // G1CollectedHeap::ref_processing_init() about
1461       // how reference processing currently works in G1.
1462 
1463       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1464       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1465 
1466       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1467       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1468 
1469       ref_processor_stw()->enable_discovery();
1470       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1471 
1472       // Do collection work
1473       {
1474         HandleMark hm;  // Discard invalid handles created during gc
1475         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1476       }
1477 
1478       assert(num_free_regions() == 0, "we should not have added any free regions");
1479       rebuild_region_sets(false /* free_list_only */);
1480 
1481       // Enqueue any discovered reference objects that have
1482       // not been removed from the discovered lists.
1483       ref_processor_stw()->enqueue_discovered_references();
1484 
1485       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1486 
1487       MemoryService::track_memory_usage();
1488 
1489       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1490       ref_processor_stw()->verify_no_references_recorded();
1491 
1492       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1493       ClassLoaderDataGraph::purge();
1494       MetaspaceAux::verify_metrics();
1495 
1496       // Note: since we've just done a full GC, concurrent
1497       // marking is no longer active. Therefore we need not
1498       // re-enable reference discovery for the CM ref processor.
1499       // That will be done at the start of the next marking cycle.
1500       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1501       ref_processor_cm()->verify_no_references_recorded();
1502 
1503       reset_gc_time_stamp();
1504       // Since everything potentially moved, we will clear all remembered
1505       // sets, and clear all cards.  Later we will rebuild remembered
1506       // sets. We will also reset the GC time stamps of the regions.
1507       clear_rsets_post_compaction();
1508       check_gc_time_stamps();
1509 
1510       // Resize the heap if necessary.
1511       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1512 
1513       if (_hr_printer.is_active()) {
1514         // We should do this after we potentially resize the heap so
1515         // that all the COMMIT / UNCOMMIT events are generated before
1516         // the end GC event.
1517 
1518         print_hrm_post_compaction();
1519         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1520       }
1521 
1522       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1523       if (hot_card_cache->use_cache()) {
1524         hot_card_cache->reset_card_counts();
1525         hot_card_cache->reset_hot_cache();
1526       }
1527 
1528       // Rebuild remembered sets of all regions.
1529       uint n_workers =
1530         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1531                                                 workers()->active_workers(),
1532                                                 Threads::number_of_non_daemon_threads());
1533       workers()->set_active_workers(n_workers);
1534 
1535       ParRebuildRSTask rebuild_rs_task(this);
1536       workers()->run_task(&rebuild_rs_task);
1537 
1538       // Rebuild the strong code root lists for each region
1539       rebuild_strong_code_roots();
1540 
1541       if (true) { // FIXME
1542         MetaspaceGC::compute_new_size();
1543       }
1544 
1545 #ifdef TRACESPINNING
1546       ParallelTaskTerminator::print_termination_counts();
1547 #endif
1548 
1549       // Discard all rset updates
1550       JavaThread::dirty_card_queue_set().abandon_logs();
1551       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1552 
1553       _young_list->reset_sampled_info();
1554       // At this point there should be no regions in the
1555       // entire heap tagged as young.
1556       assert(check_young_list_empty(true /* check_heap */),
1557              "young list should be empty at this point");
1558 
1559       // Update the number of full collections that have been completed.
1560       increment_old_marking_cycles_completed(false /* concurrent */);
1561 
1562       _hrm.verify_optional();
1563       verify_region_sets_optional();
1564 
1565       verify_after_gc();
1566 
1567       // Clear the previous marking bitmap, if needed for bitmap verification.
1568       // Note we cannot do this when we clear the next marking bitmap in
1569       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1570       // objects marked during a full GC against the previous bitmap.
1571       // But we need to clear it before calling check_bitmaps below since
1572       // the full GC has compacted objects and updated TAMS but not updated
1573       // the prev bitmap.
1574       if (G1VerifyBitmaps) {
1575         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1576       }
1577       check_bitmaps("Full GC End");
1578 
1579       // Start a new incremental collection set for the next pause
1580       assert(g1_policy()->collection_set() == NULL, "must be");
1581       g1_policy()->start_incremental_cset_building();
1582 
1583       clear_cset_fast_test();
1584 
1585       _allocator->init_mutator_alloc_region();
1586 
1587       g1_policy()->record_full_collection_end();
1588 
1589       if (G1Log::fine()) {
1590         g1_policy()->print_heap_transition();
1591       }
1592 
1593       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1594       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1595       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1596       // before any GC notifications are raised.
1597       g1mm()->update_sizes();
1598 
1599       gc_epilogue(true);
1600     }
1601 
1602     if (G1Log::finer()) {
1603       g1_policy()->print_detailed_heap_transition(true /* full */);
1604     }
1605 
1606     print_heap_after_gc();
1607     trace_heap_after_gc(gc_tracer);
1608 
1609     post_full_gc_dump(gc_timer);
1610 
1611     gc_timer->register_gc_end();
1612     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1613   }
1614 
1615   return true;
1616 }
1617 
1618 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1619   // do_collection() will return whether it succeeded in performing
1620   // the GC. Currently, there is no facility on the
1621   // do_full_collection() API to notify the caller than the collection
1622   // did not succeed (e.g., because it was locked out by the GC
1623   // locker). So, right now, we'll ignore the return value.
1624   bool dummy = do_collection(true,                /* explicit_gc */
1625                              clear_all_soft_refs,
1626                              0                    /* word_size */);
1627 }
1628 
1629 // This code is mostly copied from TenuredGeneration.
1630 void
1631 G1CollectedHeap::
1632 resize_if_necessary_after_full_collection(size_t word_size) {
1633   // Include the current allocation, if any, and bytes that will be
1634   // pre-allocated to support collections, as "used".
1635   const size_t used_after_gc = used();
1636   const size_t capacity_after_gc = capacity();
1637   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1638 
1639   // This is enforced in arguments.cpp.
1640   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1641          "otherwise the code below doesn't make sense");
1642 
1643   // We don't have floating point command-line arguments
1644   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1645   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1646   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1647   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1648 
1649   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1650   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1651 
1652   // We have to be careful here as these two calculations can overflow
1653   // 32-bit size_t's.
1654   double used_after_gc_d = (double) used_after_gc;
1655   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1656   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1657 
1658   // Let's make sure that they are both under the max heap size, which
1659   // by default will make them fit into a size_t.
1660   double desired_capacity_upper_bound = (double) max_heap_size;
1661   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1662                                     desired_capacity_upper_bound);
1663   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1664                                     desired_capacity_upper_bound);
1665 
1666   // We can now safely turn them into size_t's.
1667   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1668   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1669 
1670   // This assert only makes sense here, before we adjust them
1671   // with respect to the min and max heap size.
1672   assert(minimum_desired_capacity <= maximum_desired_capacity,
1673          err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1674                  "maximum_desired_capacity = " SIZE_FORMAT,
1675                  minimum_desired_capacity, maximum_desired_capacity));
1676 
1677   // Should not be greater than the heap max size. No need to adjust
1678   // it with respect to the heap min size as it's a lower bound (i.e.,
1679   // we'll try to make the capacity larger than it, not smaller).
1680   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1681   // Should not be less than the heap min size. No need to adjust it
1682   // with respect to the heap max size as it's an upper bound (i.e.,
1683   // we'll try to make the capacity smaller than it, not greater).
1684   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1685 
1686   if (capacity_after_gc < minimum_desired_capacity) {
1687     // Don't expand unless it's significant
1688     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1689     ergo_verbose4(ErgoHeapSizing,
1690                   "attempt heap expansion",
1691                   ergo_format_reason("capacity lower than "
1692                                      "min desired capacity after Full GC")
1693                   ergo_format_byte("capacity")
1694                   ergo_format_byte("occupancy")
1695                   ergo_format_byte_perc("min desired capacity"),
1696                   capacity_after_gc, used_after_gc,
1697                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1698     expand(expand_bytes);
1699 
1700     // No expansion, now see if we want to shrink
1701   } else if (capacity_after_gc > maximum_desired_capacity) {
1702     // Capacity too large, compute shrinking size
1703     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1704     ergo_verbose4(ErgoHeapSizing,
1705                   "attempt heap shrinking",
1706                   ergo_format_reason("capacity higher than "
1707                                      "max desired capacity after Full GC")
1708                   ergo_format_byte("capacity")
1709                   ergo_format_byte("occupancy")
1710                   ergo_format_byte_perc("max desired capacity"),
1711                   capacity_after_gc, used_after_gc,
1712                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1713     shrink(shrink_bytes);
1714   }
1715 }
1716 
1717 
1718 HeapWord*
1719 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1720                                            AllocationContext_t context,
1721                                            bool* succeeded) {
1722   assert_at_safepoint(true /* should_be_vm_thread */);
1723 
1724   *succeeded = true;
1725   // Let's attempt the allocation first.
1726   HeapWord* result =
1727     attempt_allocation_at_safepoint(word_size,
1728                                     context,
1729                                     false /* expect_null_mutator_alloc_region */);
1730   if (result != NULL) {
1731     assert(*succeeded, "sanity");
1732     return result;
1733   }
1734 
1735   // In a G1 heap, we're supposed to keep allocation from failing by
1736   // incremental pauses.  Therefore, at least for now, we'll favor
1737   // expansion over collection.  (This might change in the future if we can
1738   // do something smarter than full collection to satisfy a failed alloc.)
1739   result = expand_and_allocate(word_size, context);
1740   if (result != NULL) {
1741     assert(*succeeded, "sanity");
1742     return result;
1743   }
1744 
1745   // Expansion didn't work, we'll try to do a Full GC.
1746   bool gc_succeeded = do_collection(false, /* explicit_gc */
1747                                     false, /* clear_all_soft_refs */
1748                                     word_size);
1749   if (!gc_succeeded) {
1750     *succeeded = false;
1751     return NULL;
1752   }
1753 
1754   // Retry the allocation
1755   result = attempt_allocation_at_safepoint(word_size,
1756                                            context,
1757                                            true /* expect_null_mutator_alloc_region */);
1758   if (result != NULL) {
1759     assert(*succeeded, "sanity");
1760     return result;
1761   }
1762 
1763   // Then, try a Full GC that will collect all soft references.
1764   gc_succeeded = do_collection(false, /* explicit_gc */
1765                                true,  /* clear_all_soft_refs */
1766                                word_size);
1767   if (!gc_succeeded) {
1768     *succeeded = false;
1769     return NULL;
1770   }
1771 
1772   // Retry the allocation once more
1773   result = attempt_allocation_at_safepoint(word_size,
1774                                            context,
1775                                            true /* expect_null_mutator_alloc_region */);
1776   if (result != NULL) {
1777     assert(*succeeded, "sanity");
1778     return result;
1779   }
1780 
1781   assert(!collector_policy()->should_clear_all_soft_refs(),
1782          "Flag should have been handled and cleared prior to this point");
1783 
1784   // What else?  We might try synchronous finalization later.  If the total
1785   // space available is large enough for the allocation, then a more
1786   // complete compaction phase than we've tried so far might be
1787   // appropriate.
1788   assert(*succeeded, "sanity");
1789   return NULL;
1790 }
1791 
1792 // Attempting to expand the heap sufficiently
1793 // to support an allocation of the given "word_size".  If
1794 // successful, perform the allocation and return the address of the
1795 // allocated block, or else "NULL".
1796 
1797 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1798   assert_at_safepoint(true /* should_be_vm_thread */);
1799 
1800   verify_region_sets_optional();
1801 
1802   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1803   ergo_verbose1(ErgoHeapSizing,
1804                 "attempt heap expansion",
1805                 ergo_format_reason("allocation request failed")
1806                 ergo_format_byte("allocation request"),
1807                 word_size * HeapWordSize);
1808   if (expand(expand_bytes)) {
1809     _hrm.verify_optional();
1810     verify_region_sets_optional();
1811     return attempt_allocation_at_safepoint(word_size,
1812                                            context,
1813                                            false /* expect_null_mutator_alloc_region */);
1814   }
1815   return NULL;
1816 }
1817 
1818 bool G1CollectedHeap::expand(size_t expand_bytes) {
1819   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1820   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1821                                        HeapRegion::GrainBytes);
1822   ergo_verbose2(ErgoHeapSizing,
1823                 "expand the heap",
1824                 ergo_format_byte("requested expansion amount")
1825                 ergo_format_byte("attempted expansion amount"),
1826                 expand_bytes, aligned_expand_bytes);
1827 
1828   if (is_maximal_no_gc()) {
1829     ergo_verbose0(ErgoHeapSizing,
1830                       "did not expand the heap",
1831                       ergo_format_reason("heap already fully expanded"));
1832     return false;
1833   }
1834 
1835   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1836   assert(regions_to_expand > 0, "Must expand by at least one region");
1837 
1838   uint expanded_by = _hrm.expand_by(regions_to_expand);
1839 
1840   if (expanded_by > 0) {
1841     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1842     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1843     g1_policy()->record_new_heap_size(num_regions());
1844   } else {
1845     ergo_verbose0(ErgoHeapSizing,
1846                   "did not expand the heap",
1847                   ergo_format_reason("heap expansion operation failed"));
1848     // The expansion of the virtual storage space was unsuccessful.
1849     // Let's see if it was because we ran out of swap.
1850     if (G1ExitOnExpansionFailure &&
1851         _hrm.available() >= regions_to_expand) {
1852       // We had head room...
1853       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1854     }
1855   }
1856   return regions_to_expand > 0;
1857 }
1858 
1859 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1860   size_t aligned_shrink_bytes =
1861     ReservedSpace::page_align_size_down(shrink_bytes);
1862   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1863                                          HeapRegion::GrainBytes);
1864   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1865 
1866   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1867   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1868 
1869   ergo_verbose3(ErgoHeapSizing,
1870                 "shrink the heap",
1871                 ergo_format_byte("requested shrinking amount")
1872                 ergo_format_byte("aligned shrinking amount")
1873                 ergo_format_byte("attempted shrinking amount"),
1874                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1875   if (num_regions_removed > 0) {
1876     g1_policy()->record_new_heap_size(num_regions());
1877   } else {
1878     ergo_verbose0(ErgoHeapSizing,
1879                   "did not shrink the heap",
1880                   ergo_format_reason("heap shrinking operation failed"));
1881   }
1882 }
1883 
1884 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1885   verify_region_sets_optional();
1886 
1887   // We should only reach here at the end of a Full GC which means we
1888   // should not not be holding to any GC alloc regions. The method
1889   // below will make sure of that and do any remaining clean up.
1890   _allocator->abandon_gc_alloc_regions();
1891 
1892   // Instead of tearing down / rebuilding the free lists here, we
1893   // could instead use the remove_all_pending() method on free_list to
1894   // remove only the ones that we need to remove.
1895   tear_down_region_sets(true /* free_list_only */);
1896   shrink_helper(shrink_bytes);
1897   rebuild_region_sets(true /* free_list_only */);
1898 
1899   _hrm.verify_optional();
1900   verify_region_sets_optional();
1901 }
1902 
1903 // Public methods.
1904 
1905 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1906 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1907 #endif // _MSC_VER
1908 
1909 
1910 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1911   CollectedHeap(),
1912   _g1_policy(policy_),
1913   _dirty_card_queue_set(false),
1914   _into_cset_dirty_card_queue_set(false),
1915   _is_alive_closure_cm(this),
1916   _is_alive_closure_stw(this),
1917   _ref_processor_cm(NULL),
1918   _ref_processor_stw(NULL),
1919   _bot_shared(NULL),
1920   _cg1r(NULL),
1921   _g1mm(NULL),
1922   _refine_cte_cl(NULL),
1923   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1924   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1925   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1926   _humongous_reclaim_candidates(),
1927   _has_humongous_reclaim_candidates(false),
1928   _archive_allocator(NULL),
1929   _free_regions_coming(false),
1930   _young_list(new YoungList(this)),
1931   _gc_time_stamp(0),
1932   _summary_bytes_used(0),
1933   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1934   _old_plab_stats(OldPLABSize, PLABWeight),
1935   _expand_heap_after_alloc_failure(true),
1936   _surviving_young_words(NULL),
1937   _old_marking_cycles_started(0),
1938   _old_marking_cycles_completed(0),
1939   _heap_summary_sent(false),
1940   _in_cset_fast_test(),
1941   _dirty_cards_region_list(NULL),
1942   _worker_cset_start_region(NULL),
1943   _worker_cset_start_region_time_stamp(NULL),
1944   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1945   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1946   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1947   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1948 
1949   _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1950                           /* are_GC_task_threads */true,
1951                           /* are_ConcurrentGC_threads */false);
1952   _workers->initialize_workers();
1953 
1954   _allocator = G1Allocator::create_allocator(this);
1955   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1956 
1957   // Override the default _filler_array_max_size so that no humongous filler
1958   // objects are created.
1959   _filler_array_max_size = _humongous_object_threshold_in_words;
1960 
1961   uint n_queues = ParallelGCThreads;
1962   _task_queues = new RefToScanQueueSet(n_queues);
1963 
1964   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1965   assert(n_rem_sets > 0, "Invariant.");
1966 
1967   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1968   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1969   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1970 
1971   for (uint i = 0; i < n_queues; i++) {
1972     RefToScanQueue* q = new RefToScanQueue();
1973     q->initialize();
1974     _task_queues->register_queue(i, q);
1975     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1976   }
1977   clear_cset_start_regions();
1978 
1979   // Initialize the G1EvacuationFailureALot counters and flags.
1980   NOT_PRODUCT(reset_evacuation_should_fail();)
1981 
1982   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1983 }
1984 
1985 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1986                                                                  size_t size,
1987                                                                  size_t translation_factor) {
1988   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1989   // Allocate a new reserved space, preferring to use large pages.
1990   ReservedSpace rs(size, preferred_page_size);
1991   G1RegionToSpaceMapper* result  =
1992     G1RegionToSpaceMapper::create_mapper(rs,
1993                                          size,
1994                                          rs.alignment(),
1995                                          HeapRegion::GrainBytes,
1996                                          translation_factor,
1997                                          mtGC);
1998   if (TracePageSizes) {
1999     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2000                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2001   }
2002   return result;
2003 }
2004 
2005 jint G1CollectedHeap::initialize() {
2006   CollectedHeap::pre_initialize();
2007   os::enable_vtime();
2008 
2009   G1Log::init();
2010 
2011   // Necessary to satisfy locking discipline assertions.
2012 
2013   MutexLocker x(Heap_lock);
2014 
2015   // We have to initialize the printer before committing the heap, as
2016   // it will be used then.
2017   _hr_printer.set_active(G1PrintHeapRegions);
2018 
2019   // While there are no constraints in the GC code that HeapWordSize
2020   // be any particular value, there are multiple other areas in the
2021   // system which believe this to be true (e.g. oop->object_size in some
2022   // cases incorrectly returns the size in wordSize units rather than
2023   // HeapWordSize).
2024   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2025 
2026   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2027   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2028   size_t heap_alignment = collector_policy()->heap_alignment();
2029 
2030   // Ensure that the sizes are properly aligned.
2031   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2032   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2033   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2034 
2035   _refine_cte_cl = new RefineCardTableEntryClosure();
2036 
2037   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2038 
2039   // Reserve the maximum.
2040 
2041   // When compressed oops are enabled, the preferred heap base
2042   // is calculated by subtracting the requested size from the
2043   // 32Gb boundary and using the result as the base address for
2044   // heap reservation. If the requested size is not aligned to
2045   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2046   // into the ReservedHeapSpace constructor) then the actual
2047   // base of the reserved heap may end up differing from the
2048   // address that was requested (i.e. the preferred heap base).
2049   // If this happens then we could end up using a non-optimal
2050   // compressed oops mode.
2051 
2052   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2053                                                  heap_alignment);
2054 
2055   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2056 
2057   // Create the barrier set for the entire reserved region.
2058   G1SATBCardTableLoggingModRefBS* bs
2059     = new G1SATBCardTableLoggingModRefBS(reserved_region());
2060   bs->initialize();
2061   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2062   set_barrier_set(bs);
2063 
2064   // Also create a G1 rem set.
2065   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2066 
2067   // Carve out the G1 part of the heap.
2068 
2069   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2070   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2071   G1RegionToSpaceMapper* heap_storage =
2072     G1RegionToSpaceMapper::create_mapper(g1_rs,
2073                                          g1_rs.size(),
2074                                          page_size,
2075                                          HeapRegion::GrainBytes,
2076                                          1,
2077                                          mtJavaHeap);
2078   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2079                        max_byte_size, page_size,
2080                        heap_rs.base(),
2081                        heap_rs.size());
2082   heap_storage->set_mapping_changed_listener(&_listener);
2083 
2084   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2085   G1RegionToSpaceMapper* bot_storage =
2086     create_aux_memory_mapper("Block offset table",
2087                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2088                              G1BlockOffsetSharedArray::heap_map_factor());
2089 
2090   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2091   G1RegionToSpaceMapper* cardtable_storage =
2092     create_aux_memory_mapper("Card table",
2093                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2094                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
2095 
2096   G1RegionToSpaceMapper* card_counts_storage =
2097     create_aux_memory_mapper("Card counts table",
2098                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2099                              G1CardCounts::heap_map_factor());
2100 
2101   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2102   G1RegionToSpaceMapper* prev_bitmap_storage =
2103     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2104   G1RegionToSpaceMapper* next_bitmap_storage =
2105     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2106 
2107   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2108   g1_barrier_set()->initialize(cardtable_storage);
2109    // Do later initialization work for concurrent refinement.
2110   _cg1r->init(card_counts_storage);
2111 
2112   // 6843694 - ensure that the maximum region index can fit
2113   // in the remembered set structures.
2114   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2115   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2116 
2117   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2118   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2119   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2120             "too many cards per region");
2121 
2122   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2123 
2124   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2125 
2126   {
2127     HeapWord* start = _hrm.reserved().start();
2128     HeapWord* end = _hrm.reserved().end();
2129     size_t granularity = HeapRegion::GrainBytes;
2130 
2131     _in_cset_fast_test.initialize(start, end, granularity);
2132     _humongous_reclaim_candidates.initialize(start, end, granularity);
2133   }
2134 
2135   // Create the ConcurrentMark data structure and thread.
2136   // (Must do this late, so that "max_regions" is defined.)
2137   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2138   if (_cm == NULL || !_cm->completed_initialization()) {
2139     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2140     return JNI_ENOMEM;
2141   }
2142   _cmThread = _cm->cmThread();
2143 
2144   // Initialize the from_card cache structure of HeapRegionRemSet.
2145   HeapRegionRemSet::init_heap(max_regions());
2146 
2147   // Now expand into the initial heap size.
2148   if (!expand(init_byte_size)) {
2149     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2150     return JNI_ENOMEM;
2151   }
2152 
2153   // Perform any initialization actions delegated to the policy.
2154   g1_policy()->init();
2155 
2156   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2157                                                SATB_Q_FL_lock,
2158                                                G1SATBProcessCompletedThreshold,
2159                                                Shared_SATB_Q_lock);
2160 
2161   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2162                                                 DirtyCardQ_CBL_mon,
2163                                                 DirtyCardQ_FL_lock,
2164                                                 concurrent_g1_refine()->yellow_zone(),
2165                                                 concurrent_g1_refine()->red_zone(),
2166                                                 Shared_DirtyCardQ_lock);
2167 
2168   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2169                                     DirtyCardQ_CBL_mon,
2170                                     DirtyCardQ_FL_lock,
2171                                     -1, // never trigger processing
2172                                     -1, // no limit on length
2173                                     Shared_DirtyCardQ_lock,
2174                                     &JavaThread::dirty_card_queue_set());
2175 
2176   // Initialize the card queue set used to hold cards containing
2177   // references into the collection set.
2178   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2179                                              DirtyCardQ_CBL_mon,
2180                                              DirtyCardQ_FL_lock,
2181                                              -1, // never trigger processing
2182                                              -1, // no limit on length
2183                                              Shared_DirtyCardQ_lock,
2184                                              &JavaThread::dirty_card_queue_set());
2185 
2186   // Here we allocate the dummy HeapRegion that is required by the
2187   // G1AllocRegion class.
2188   HeapRegion* dummy_region = _hrm.get_dummy_region();
2189 
2190   // We'll re-use the same region whether the alloc region will
2191   // require BOT updates or not and, if it doesn't, then a non-young
2192   // region will complain that it cannot support allocations without
2193   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2194   dummy_region->set_eden();
2195   // Make sure it's full.
2196   dummy_region->set_top(dummy_region->end());
2197   G1AllocRegion::setup(this, dummy_region);
2198 
2199   _allocator->init_mutator_alloc_region();
2200 
2201   // Do create of the monitoring and management support so that
2202   // values in the heap have been properly initialized.
2203   _g1mm = new G1MonitoringSupport(this);
2204 
2205   G1StringDedup::initialize();
2206 
2207   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2208   for (uint i = 0; i < ParallelGCThreads; i++) {
2209     new (&_preserved_objs[i]) OopAndMarkOopStack();
2210   }
2211 
2212   return JNI_OK;
2213 }
2214 
2215 void G1CollectedHeap::stop() {
2216   // Stop all concurrent threads. We do this to make sure these threads
2217   // do not continue to execute and access resources (e.g. gclog_or_tty)
2218   // that are destroyed during shutdown.
2219   _cg1r->stop();
2220   _cmThread->stop();
2221   if (G1StringDedup::is_enabled()) {
2222     G1StringDedup::stop();
2223   }
2224 }
2225 
2226 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2227   return HeapRegion::max_region_size();
2228 }
2229 
2230 void G1CollectedHeap::post_initialize() {
2231   CollectedHeap::post_initialize();
2232   ref_processing_init();
2233 }
2234 
2235 void G1CollectedHeap::ref_processing_init() {
2236   // Reference processing in G1 currently works as follows:
2237   //
2238   // * There are two reference processor instances. One is
2239   //   used to record and process discovered references
2240   //   during concurrent marking; the other is used to
2241   //   record and process references during STW pauses
2242   //   (both full and incremental).
2243   // * Both ref processors need to 'span' the entire heap as
2244   //   the regions in the collection set may be dotted around.
2245   //
2246   // * For the concurrent marking ref processor:
2247   //   * Reference discovery is enabled at initial marking.
2248   //   * Reference discovery is disabled and the discovered
2249   //     references processed etc during remarking.
2250   //   * Reference discovery is MT (see below).
2251   //   * Reference discovery requires a barrier (see below).
2252   //   * Reference processing may or may not be MT
2253   //     (depending on the value of ParallelRefProcEnabled
2254   //     and ParallelGCThreads).
2255   //   * A full GC disables reference discovery by the CM
2256   //     ref processor and abandons any entries on it's
2257   //     discovered lists.
2258   //
2259   // * For the STW processor:
2260   //   * Non MT discovery is enabled at the start of a full GC.
2261   //   * Processing and enqueueing during a full GC is non-MT.
2262   //   * During a full GC, references are processed after marking.
2263   //
2264   //   * Discovery (may or may not be MT) is enabled at the start
2265   //     of an incremental evacuation pause.
2266   //   * References are processed near the end of a STW evacuation pause.
2267   //   * For both types of GC:
2268   //     * Discovery is atomic - i.e. not concurrent.
2269   //     * Reference discovery will not need a barrier.
2270 
2271   MemRegion mr = reserved_region();
2272 
2273   // Concurrent Mark ref processor
2274   _ref_processor_cm =
2275     new ReferenceProcessor(mr,    // span
2276                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2277                                 // mt processing
2278                            ParallelGCThreads,
2279                                 // degree of mt processing
2280                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2281                                 // mt discovery
2282                            MAX2(ParallelGCThreads, ConcGCThreads),
2283                                 // degree of mt discovery
2284                            false,
2285                                 // Reference discovery is not atomic
2286                            &_is_alive_closure_cm);
2287                                 // is alive closure
2288                                 // (for efficiency/performance)
2289 
2290   // STW ref processor
2291   _ref_processor_stw =
2292     new ReferenceProcessor(mr,    // span
2293                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2294                                 // mt processing
2295                            ParallelGCThreads,
2296                                 // degree of mt processing
2297                            (ParallelGCThreads > 1),
2298                                 // mt discovery
2299                            ParallelGCThreads,
2300                                 // degree of mt discovery
2301                            true,
2302                                 // Reference discovery is atomic
2303                            &_is_alive_closure_stw);
2304                                 // is alive closure
2305                                 // (for efficiency/performance)
2306 }
2307 
2308 size_t G1CollectedHeap::capacity() const {
2309   return _hrm.length() * HeapRegion::GrainBytes;
2310 }
2311 
2312 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2313   assert(!hr->is_continues_humongous(), "pre-condition");
2314   hr->reset_gc_time_stamp();
2315   if (hr->is_starts_humongous()) {
2316     uint first_index = hr->hrm_index() + 1;
2317     uint last_index = hr->last_hc_index();
2318     for (uint i = first_index; i < last_index; i += 1) {
2319       HeapRegion* chr = region_at(i);
2320       assert(chr->is_continues_humongous(), "sanity");
2321       chr->reset_gc_time_stamp();
2322     }
2323   }
2324 }
2325 
2326 #ifndef PRODUCT
2327 
2328 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2329 private:
2330   unsigned _gc_time_stamp;
2331   bool _failures;
2332 
2333 public:
2334   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2335     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2336 
2337   virtual bool doHeapRegion(HeapRegion* hr) {
2338     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2339     if (_gc_time_stamp != region_gc_time_stamp) {
2340       gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2341                              "expected %d", HR_FORMAT_PARAMS(hr),
2342                              region_gc_time_stamp, _gc_time_stamp);
2343       _failures = true;
2344     }
2345     return false;
2346   }
2347 
2348   bool failures() { return _failures; }
2349 };
2350 
2351 void G1CollectedHeap::check_gc_time_stamps() {
2352   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2353   heap_region_iterate(&cl);
2354   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2355 }
2356 #endif // PRODUCT
2357 
2358 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2359                                                  DirtyCardQueue* into_cset_dcq,
2360                                                  bool concurrent,
2361                                                  uint worker_i) {
2362   // Clean cards in the hot card cache
2363   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2364   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2365 
2366   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2367   size_t n_completed_buffers = 0;
2368   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2369     n_completed_buffers++;
2370   }
2371   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2372   dcqs.clear_n_completed_buffers();
2373   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2374 }
2375 
2376 
2377 // Computes the sum of the storage used by the various regions.
2378 size_t G1CollectedHeap::used() const {
2379   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2380   if (_archive_allocator != NULL) {
2381     result += _archive_allocator->used();
2382   }
2383   return result;
2384 }
2385 
2386 size_t G1CollectedHeap::used_unlocked() const {
2387   return _summary_bytes_used;
2388 }
2389 
2390 class SumUsedClosure: public HeapRegionClosure {
2391   size_t _used;
2392 public:
2393   SumUsedClosure() : _used(0) {}
2394   bool doHeapRegion(HeapRegion* r) {
2395     if (!r->is_continues_humongous()) {
2396       _used += r->used();
2397     }
2398     return false;
2399   }
2400   size_t result() { return _used; }
2401 };
2402 
2403 size_t G1CollectedHeap::recalculate_used() const {
2404   double recalculate_used_start = os::elapsedTime();
2405 
2406   SumUsedClosure blk;
2407   heap_region_iterate(&blk);
2408 
2409   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2410   return blk.result();
2411 }
2412 
2413 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2414   switch (cause) {
2415     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2416     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2417     case GCCause::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2418     case GCCause::_g1_humongous_allocation: return true;
2419     case GCCause::_update_allocation_context_stats_inc: return true;
2420     case GCCause::_wb_conc_mark:            return true;
2421     default:                                return false;
2422   }
2423 }
2424 
2425 #ifndef PRODUCT
2426 void G1CollectedHeap::allocate_dummy_regions() {
2427   // Let's fill up most of the region
2428   size_t word_size = HeapRegion::GrainWords - 1024;
2429   // And as a result the region we'll allocate will be humongous.
2430   guarantee(is_humongous(word_size), "sanity");
2431 
2432   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2433     // Let's use the existing mechanism for the allocation
2434     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2435                                                  AllocationContext::system());
2436     if (dummy_obj != NULL) {
2437       MemRegion mr(dummy_obj, word_size);
2438       CollectedHeap::fill_with_object(mr);
2439     } else {
2440       // If we can't allocate once, we probably cannot allocate
2441       // again. Let's get out of the loop.
2442       break;
2443     }
2444   }
2445 }
2446 #endif // !PRODUCT
2447 
2448 void G1CollectedHeap::increment_old_marking_cycles_started() {
2449   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2450     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2451     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2452     _old_marking_cycles_started, _old_marking_cycles_completed));
2453 
2454   _old_marking_cycles_started++;
2455 }
2456 
2457 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2458   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2459 
2460   // We assume that if concurrent == true, then the caller is a
2461   // concurrent thread that was joined the Suspendible Thread
2462   // Set. If there's ever a cheap way to check this, we should add an
2463   // assert here.
2464 
2465   // Given that this method is called at the end of a Full GC or of a
2466   // concurrent cycle, and those can be nested (i.e., a Full GC can
2467   // interrupt a concurrent cycle), the number of full collections
2468   // completed should be either one (in the case where there was no
2469   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2470   // behind the number of full collections started.
2471 
2472   // This is the case for the inner caller, i.e. a Full GC.
2473   assert(concurrent ||
2474          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2475          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2476          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2477                  "is inconsistent with _old_marking_cycles_completed = %u",
2478                  _old_marking_cycles_started, _old_marking_cycles_completed));
2479 
2480   // This is the case for the outer caller, i.e. the concurrent cycle.
2481   assert(!concurrent ||
2482          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2483          err_msg("for outer caller (concurrent cycle): "
2484                  "_old_marking_cycles_started = %u "
2485                  "is inconsistent with _old_marking_cycles_completed = %u",
2486                  _old_marking_cycles_started, _old_marking_cycles_completed));
2487 
2488   _old_marking_cycles_completed += 1;
2489 
2490   // We need to clear the "in_progress" flag in the CM thread before
2491   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2492   // is set) so that if a waiter requests another System.gc() it doesn't
2493   // incorrectly see that a marking cycle is still in progress.
2494   if (concurrent) {
2495     _cmThread->set_idle();
2496   }
2497 
2498   // This notify_all() will ensure that a thread that called
2499   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2500   // and it's waiting for a full GC to finish will be woken up. It is
2501   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2502   FullGCCount_lock->notify_all();
2503 }
2504 
2505 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2506   collector_state()->set_concurrent_cycle_started(true);
2507   _gc_timer_cm->register_gc_start(start_time);
2508 
2509   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2510   trace_heap_before_gc(_gc_tracer_cm);
2511 }
2512 
2513 void G1CollectedHeap::register_concurrent_cycle_end() {
2514   if (collector_state()->concurrent_cycle_started()) {
2515     if (_cm->has_aborted()) {
2516       _gc_tracer_cm->report_concurrent_mode_failure();
2517     }
2518 
2519     _gc_timer_cm->register_gc_end();
2520     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2521 
2522     // Clear state variables to prepare for the next concurrent cycle.
2523      collector_state()->set_concurrent_cycle_started(false);
2524     _heap_summary_sent = false;
2525   }
2526 }
2527 
2528 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2529   if (collector_state()->concurrent_cycle_started()) {
2530     // This function can be called when:
2531     //  the cleanup pause is run
2532     //  the concurrent cycle is aborted before the cleanup pause.
2533     //  the concurrent cycle is aborted after the cleanup pause,
2534     //   but before the concurrent cycle end has been registered.
2535     // Make sure that we only send the heap information once.
2536     if (!_heap_summary_sent) {
2537       trace_heap_after_gc(_gc_tracer_cm);
2538       _heap_summary_sent = true;
2539     }
2540   }
2541 }
2542 
2543 void G1CollectedHeap::collect(GCCause::Cause cause) {
2544   assert_heap_not_locked();
2545 
2546   uint gc_count_before;
2547   uint old_marking_count_before;
2548   uint full_gc_count_before;
2549   bool retry_gc;
2550 
2551   do {
2552     retry_gc = false;
2553 
2554     {
2555       MutexLocker ml(Heap_lock);
2556 
2557       // Read the GC count while holding the Heap_lock
2558       gc_count_before = total_collections();
2559       full_gc_count_before = total_full_collections();
2560       old_marking_count_before = _old_marking_cycles_started;
2561     }
2562 
2563     if (should_do_concurrent_full_gc(cause)) {
2564       // Schedule an initial-mark evacuation pause that will start a
2565       // concurrent cycle. We're setting word_size to 0 which means that
2566       // we are not requesting a post-GC allocation.
2567       VM_G1IncCollectionPause op(gc_count_before,
2568                                  0,     /* word_size */
2569                                  true,  /* should_initiate_conc_mark */
2570                                  g1_policy()->max_pause_time_ms(),
2571                                  cause);
2572       op.set_allocation_context(AllocationContext::current());
2573 
2574       VMThread::execute(&op);
2575       if (!op.pause_succeeded()) {
2576         if (old_marking_count_before == _old_marking_cycles_started) {
2577           retry_gc = op.should_retry_gc();
2578         } else {
2579           // A Full GC happened while we were trying to schedule the
2580           // initial-mark GC. No point in starting a new cycle given
2581           // that the whole heap was collected anyway.
2582         }
2583 
2584         if (retry_gc) {
2585           if (GC_locker::is_active_and_needs_gc()) {
2586             GC_locker::stall_until_clear();
2587           }
2588         }
2589       }
2590     } else {
2591       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2592           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2593 
2594         // Schedule a standard evacuation pause. We're setting word_size
2595         // to 0 which means that we are not requesting a post-GC allocation.
2596         VM_G1IncCollectionPause op(gc_count_before,
2597                                    0,     /* word_size */
2598                                    false, /* should_initiate_conc_mark */
2599                                    g1_policy()->max_pause_time_ms(),
2600                                    cause);
2601         VMThread::execute(&op);
2602       } else {
2603         // Schedule a Full GC.
2604         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2605         VMThread::execute(&op);
2606       }
2607     }
2608   } while (retry_gc);
2609 }
2610 
2611 bool G1CollectedHeap::is_in(const void* p) const {
2612   if (_hrm.reserved().contains(p)) {
2613     // Given that we know that p is in the reserved space,
2614     // heap_region_containing_raw() should successfully
2615     // return the containing region.
2616     HeapRegion* hr = heap_region_containing_raw(p);
2617     return hr->is_in(p);
2618   } else {
2619     return false;
2620   }
2621 }
2622 
2623 #ifdef ASSERT
2624 bool G1CollectedHeap::is_in_exact(const void* p) const {
2625   bool contains = reserved_region().contains(p);
2626   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2627   if (contains && available) {
2628     return true;
2629   } else {
2630     return false;
2631   }
2632 }
2633 #endif
2634 
2635 // Iteration functions.
2636 
2637 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2638 
2639 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2640   ExtendedOopClosure* _cl;
2641 public:
2642   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2643   bool doHeapRegion(HeapRegion* r) {
2644     if (!r->is_continues_humongous()) {
2645       r->oop_iterate(_cl);
2646     }
2647     return false;
2648   }
2649 };
2650 
2651 // Iterates an ObjectClosure over all objects within a HeapRegion.
2652 
2653 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2654   ObjectClosure* _cl;
2655 public:
2656   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2657   bool doHeapRegion(HeapRegion* r) {
2658     if (!r->is_continues_humongous()) {
2659       r->object_iterate(_cl);
2660     }
2661     return false;
2662   }
2663 };
2664 
2665 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2666   IterateObjectClosureRegionClosure blk(cl);
2667   heap_region_iterate(&blk);
2668 }
2669 
2670 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2671   _hrm.iterate(cl);
2672 }
2673 
2674 void
2675 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2676                                          uint worker_id,
2677                                          HeapRegionClaimer *hrclaimer,
2678                                          bool concurrent) const {
2679   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2680 }
2681 
2682 // Clear the cached CSet starting regions and (more importantly)
2683 // the time stamps. Called when we reset the GC time stamp.
2684 void G1CollectedHeap::clear_cset_start_regions() {
2685   assert(_worker_cset_start_region != NULL, "sanity");
2686   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2687 
2688   for (uint i = 0; i < ParallelGCThreads; i++) {
2689     _worker_cset_start_region[i] = NULL;
2690     _worker_cset_start_region_time_stamp[i] = 0;
2691   }
2692 }
2693 
2694 // Given the id of a worker, obtain or calculate a suitable
2695 // starting region for iterating over the current collection set.
2696 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2697   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2698 
2699   HeapRegion* result = NULL;
2700   unsigned gc_time_stamp = get_gc_time_stamp();
2701 
2702   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2703     // Cached starting region for current worker was set
2704     // during the current pause - so it's valid.
2705     // Note: the cached starting heap region may be NULL
2706     // (when the collection set is empty).
2707     result = _worker_cset_start_region[worker_i];
2708     assert(result == NULL || result->in_collection_set(), "sanity");
2709     return result;
2710   }
2711 
2712   // The cached entry was not valid so let's calculate
2713   // a suitable starting heap region for this worker.
2714 
2715   // We want the parallel threads to start their collection
2716   // set iteration at different collection set regions to
2717   // avoid contention.
2718   // If we have:
2719   //          n collection set regions
2720   //          p threads
2721   // Then thread t will start at region floor ((t * n) / p)
2722 
2723   result = g1_policy()->collection_set();
2724   uint cs_size = g1_policy()->cset_region_length();
2725   uint active_workers = workers()->active_workers();
2726 
2727   uint end_ind   = (cs_size * worker_i) / active_workers;
2728   uint start_ind = 0;
2729 
2730   if (worker_i > 0 &&
2731       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2732     // Previous workers starting region is valid
2733     // so let's iterate from there
2734     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2735     result = _worker_cset_start_region[worker_i - 1];
2736   }
2737 
2738   for (uint i = start_ind; i < end_ind; i++) {
2739     result = result->next_in_collection_set();
2740   }
2741 
2742   // Note: the calculated starting heap region may be NULL
2743   // (when the collection set is empty).
2744   assert(result == NULL || result->in_collection_set(), "sanity");
2745   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2746          "should be updated only once per pause");
2747   _worker_cset_start_region[worker_i] = result;
2748   OrderAccess::storestore();
2749   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2750   return result;
2751 }
2752 
2753 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2754   HeapRegion* r = g1_policy()->collection_set();
2755   while (r != NULL) {
2756     HeapRegion* next = r->next_in_collection_set();
2757     if (cl->doHeapRegion(r)) {
2758       cl->incomplete();
2759       return;
2760     }
2761     r = next;
2762   }
2763 }
2764 
2765 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2766                                                   HeapRegionClosure *cl) {
2767   if (r == NULL) {
2768     // The CSet is empty so there's nothing to do.
2769     return;
2770   }
2771 
2772   assert(r->in_collection_set(),
2773          "Start region must be a member of the collection set.");
2774   HeapRegion* cur = r;
2775   while (cur != NULL) {
2776     HeapRegion* next = cur->next_in_collection_set();
2777     if (cl->doHeapRegion(cur) && false) {
2778       cl->incomplete();
2779       return;
2780     }
2781     cur = next;
2782   }
2783   cur = g1_policy()->collection_set();
2784   while (cur != r) {
2785     HeapRegion* next = cur->next_in_collection_set();
2786     if (cl->doHeapRegion(cur) && false) {
2787       cl->incomplete();
2788       return;
2789     }
2790     cur = next;
2791   }
2792 }
2793 
2794 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2795   HeapRegion* result = _hrm.next_region_in_heap(from);
2796   while (result != NULL && result->is_pinned()) {
2797     result = _hrm.next_region_in_heap(result);
2798   }
2799   return result;
2800 }
2801 
2802 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2803   HeapRegion* hr = heap_region_containing(addr);
2804   return hr->block_start(addr);
2805 }
2806 
2807 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2808   HeapRegion* hr = heap_region_containing(addr);
2809   return hr->block_size(addr);
2810 }
2811 
2812 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2813   HeapRegion* hr = heap_region_containing(addr);
2814   return hr->block_is_obj(addr);
2815 }
2816 
2817 bool G1CollectedHeap::supports_tlab_allocation() const {
2818   return true;
2819 }
2820 
2821 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2822   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2823 }
2824 
2825 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2826   return young_list()->eden_used_bytes();
2827 }
2828 
2829 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2830 // must be smaller than the humongous object limit.
2831 size_t G1CollectedHeap::max_tlab_size() const {
2832   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2833 }
2834 
2835 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2836   // Return the remaining space in the cur alloc region, but not less than
2837   // the min TLAB size.
2838 
2839   // Also, this value can be at most the humongous object threshold,
2840   // since we can't allow tlabs to grow big enough to accommodate
2841   // humongous objects.
2842 
2843   HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2844   size_t max_tlab = max_tlab_size() * wordSize;
2845   if (hr == NULL) {
2846     return max_tlab;
2847   } else {
2848     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2849   }
2850 }
2851 
2852 size_t G1CollectedHeap::max_capacity() const {
2853   return _hrm.reserved().byte_size();
2854 }
2855 
2856 jlong G1CollectedHeap::millis_since_last_gc() {
2857   // assert(false, "NYI");
2858   return 0;
2859 }
2860 
2861 void G1CollectedHeap::prepare_for_verify() {
2862   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2863     ensure_parsability(false);
2864   }
2865   g1_rem_set()->prepare_for_verify();
2866 }
2867 
2868 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2869                                               VerifyOption vo) {
2870   switch (vo) {
2871   case VerifyOption_G1UsePrevMarking:
2872     return hr->obj_allocated_since_prev_marking(obj);
2873   case VerifyOption_G1UseNextMarking:
2874     return hr->obj_allocated_since_next_marking(obj);
2875   case VerifyOption_G1UseMarkWord:
2876     return false;
2877   default:
2878     ShouldNotReachHere();
2879   }
2880   return false; // keep some compilers happy
2881 }
2882 
2883 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2884   switch (vo) {
2885   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2886   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2887   case VerifyOption_G1UseMarkWord:    return NULL;
2888   default:                            ShouldNotReachHere();
2889   }
2890   return NULL; // keep some compilers happy
2891 }
2892 
2893 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2894   switch (vo) {
2895   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2896   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2897   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2898   default:                            ShouldNotReachHere();
2899   }
2900   return false; // keep some compilers happy
2901 }
2902 
2903 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2904   switch (vo) {
2905   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2906   case VerifyOption_G1UseNextMarking: return "NTAMS";
2907   case VerifyOption_G1UseMarkWord:    return "NONE";
2908   default:                            ShouldNotReachHere();
2909   }
2910   return NULL; // keep some compilers happy
2911 }
2912 
2913 class VerifyRootsClosure: public OopClosure {
2914 private:
2915   G1CollectedHeap* _g1h;
2916   VerifyOption     _vo;
2917   bool             _failures;
2918 public:
2919   // _vo == UsePrevMarking -> use "prev" marking information,
2920   // _vo == UseNextMarking -> use "next" marking information,
2921   // _vo == UseMarkWord    -> use mark word from object header.
2922   VerifyRootsClosure(VerifyOption vo) :
2923     _g1h(G1CollectedHeap::heap()),
2924     _vo(vo),
2925     _failures(false) { }
2926 
2927   bool failures() { return _failures; }
2928 
2929   template <class T> void do_oop_nv(T* p) {
2930     T heap_oop = oopDesc::load_heap_oop(p);
2931     if (!oopDesc::is_null(heap_oop)) {
2932       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2933       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2934         gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2935                                "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2936         if (_vo == VerifyOption_G1UseMarkWord) {
2937           gclog_or_tty->print_cr("  Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2938         }
2939         obj->print_on(gclog_or_tty);
2940         _failures = true;
2941       }
2942     }
2943   }
2944 
2945   void do_oop(oop* p)       { do_oop_nv(p); }
2946   void do_oop(narrowOop* p) { do_oop_nv(p); }
2947 };
2948 
2949 class G1VerifyCodeRootOopClosure: public OopClosure {
2950   G1CollectedHeap* _g1h;
2951   OopClosure* _root_cl;
2952   nmethod* _nm;
2953   VerifyOption _vo;
2954   bool _failures;
2955 
2956   template <class T> void do_oop_work(T* p) {
2957     // First verify that this root is live
2958     _root_cl->do_oop(p);
2959 
2960     if (!G1VerifyHeapRegionCodeRoots) {
2961       // We're not verifying the code roots attached to heap region.
2962       return;
2963     }
2964 
2965     // Don't check the code roots during marking verification in a full GC
2966     if (_vo == VerifyOption_G1UseMarkWord) {
2967       return;
2968     }
2969 
2970     // Now verify that the current nmethod (which contains p) is
2971     // in the code root list of the heap region containing the
2972     // object referenced by p.
2973 
2974     T heap_oop = oopDesc::load_heap_oop(p);
2975     if (!oopDesc::is_null(heap_oop)) {
2976       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2977 
2978       // Now fetch the region containing the object
2979       HeapRegion* hr = _g1h->heap_region_containing(obj);
2980       HeapRegionRemSet* hrrs = hr->rem_set();
2981       // Verify that the strong code root list for this region
2982       // contains the nmethod
2983       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2984         gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2985                                "from nmethod " PTR_FORMAT " not in strong "
2986                                "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2987                                p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2988         _failures = true;
2989       }
2990     }
2991   }
2992 
2993 public:
2994   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2995     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2996 
2997   void do_oop(oop* p) { do_oop_work(p); }
2998   void do_oop(narrowOop* p) { do_oop_work(p); }
2999 
3000   void set_nmethod(nmethod* nm) { _nm = nm; }
3001   bool failures() { return _failures; }
3002 };
3003 
3004 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3005   G1VerifyCodeRootOopClosure* _oop_cl;
3006 
3007 public:
3008   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3009     _oop_cl(oop_cl) {}
3010 
3011   void do_code_blob(CodeBlob* cb) {
3012     nmethod* nm = cb->as_nmethod_or_null();
3013     if (nm != NULL) {
3014       _oop_cl->set_nmethod(nm);
3015       nm->oops_do(_oop_cl);
3016     }
3017   }
3018 };
3019 
3020 class YoungRefCounterClosure : public OopClosure {
3021   G1CollectedHeap* _g1h;
3022   int              _count;
3023  public:
3024   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3025   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3026   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3027 
3028   int count() { return _count; }
3029   void reset_count() { _count = 0; };
3030 };
3031 
3032 class VerifyKlassClosure: public KlassClosure {
3033   YoungRefCounterClosure _young_ref_counter_closure;
3034   OopClosure *_oop_closure;
3035  public:
3036   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3037   void do_klass(Klass* k) {
3038     k->oops_do(_oop_closure);
3039 
3040     _young_ref_counter_closure.reset_count();
3041     k->oops_do(&_young_ref_counter_closure);
3042     if (_young_ref_counter_closure.count() > 0) {
3043       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3044     }
3045   }
3046 };
3047 
3048 class VerifyLivenessOopClosure: public OopClosure {
3049   G1CollectedHeap* _g1h;
3050   VerifyOption _vo;
3051 public:
3052   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3053     _g1h(g1h), _vo(vo)
3054   { }
3055   void do_oop(narrowOop *p) { do_oop_work(p); }
3056   void do_oop(      oop *p) { do_oop_work(p); }
3057 
3058   template <class T> void do_oop_work(T *p) {
3059     oop obj = oopDesc::load_decode_heap_oop(p);
3060     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3061               "Dead object referenced by a not dead object");
3062   }
3063 };
3064 
3065 class VerifyObjsInRegionClosure: public ObjectClosure {
3066 private:
3067   G1CollectedHeap* _g1h;
3068   size_t _live_bytes;
3069   HeapRegion *_hr;
3070   VerifyOption _vo;
3071 public:
3072   // _vo == UsePrevMarking -> use "prev" marking information,
3073   // _vo == UseNextMarking -> use "next" marking information,
3074   // _vo == UseMarkWord    -> use mark word from object header.
3075   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3076     : _live_bytes(0), _hr(hr), _vo(vo) {
3077     _g1h = G1CollectedHeap::heap();
3078   }
3079   void do_object(oop o) {
3080     VerifyLivenessOopClosure isLive(_g1h, _vo);
3081     assert(o != NULL, "Huh?");
3082     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3083       // If the object is alive according to the mark word,
3084       // then verify that the marking information agrees.
3085       // Note we can't verify the contra-positive of the
3086       // above: if the object is dead (according to the mark
3087       // word), it may not be marked, or may have been marked
3088       // but has since became dead, or may have been allocated
3089       // since the last marking.
3090       if (_vo == VerifyOption_G1UseMarkWord) {
3091         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3092       }
3093 
3094       o->oop_iterate_no_header(&isLive);
3095       if (!_hr->obj_allocated_since_prev_marking(o)) {
3096         size_t obj_size = o->size();    // Make sure we don't overflow
3097         _live_bytes += (obj_size * HeapWordSize);
3098       }
3099     }
3100   }
3101   size_t live_bytes() { return _live_bytes; }
3102 };
3103 
3104 class VerifyArchiveOopClosure: public OopClosure {
3105 public:
3106   VerifyArchiveOopClosure(HeapRegion *hr) { }
3107   void do_oop(narrowOop *p) { do_oop_work(p); }
3108   void do_oop(      oop *p) { do_oop_work(p); }
3109 
3110   template <class T> void do_oop_work(T *p) {
3111     oop obj = oopDesc::load_decode_heap_oop(p);
3112     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3113               err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3114                       p2i(p), p2i(obj)));
3115   }
3116 };
3117 
3118 class VerifyArchiveRegionClosure: public ObjectClosure {
3119 public:
3120   VerifyArchiveRegionClosure(HeapRegion *hr) { }
3121   // Verify that all object pointers are to archive regions.
3122   void do_object(oop o) {
3123     VerifyArchiveOopClosure checkOop(NULL);
3124     assert(o != NULL, "Should not be here for NULL oops");
3125     o->oop_iterate_no_header(&checkOop);
3126   }
3127 };
3128 
3129 class VerifyRegionClosure: public HeapRegionClosure {
3130 private:
3131   bool             _par;
3132   VerifyOption     _vo;
3133   bool             _failures;
3134 public:
3135   // _vo == UsePrevMarking -> use "prev" marking information,
3136   // _vo == UseNextMarking -> use "next" marking information,
3137   // _vo == UseMarkWord    -> use mark word from object header.
3138   VerifyRegionClosure(bool par, VerifyOption vo)
3139     : _par(par),
3140       _vo(vo),
3141       _failures(false) {}
3142 
3143   bool failures() {
3144     return _failures;
3145   }
3146 
3147   bool doHeapRegion(HeapRegion* r) {
3148     // For archive regions, verify there are no heap pointers to
3149     // non-pinned regions. For all others, verify liveness info.
3150     if (r->is_archive()) {
3151       VerifyArchiveRegionClosure verify_oop_pointers(r);
3152       r->object_iterate(&verify_oop_pointers);
3153       return true;
3154     }
3155     if (!r->is_continues_humongous()) {
3156       bool failures = false;
3157       r->verify(_vo, &failures);
3158       if (failures) {
3159         _failures = true;
3160       } else {
3161         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3162         r->object_iterate(&not_dead_yet_cl);
3163         if (_vo != VerifyOption_G1UseNextMarking) {
3164           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3165             gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3166                                    "max_live_bytes " SIZE_FORMAT " "
3167                                    "< calculated " SIZE_FORMAT,
3168                                    p2i(r->bottom()), p2i(r->end()),
3169                                    r->max_live_bytes(),
3170                                  not_dead_yet_cl.live_bytes());
3171             _failures = true;
3172           }
3173         } else {
3174           // When vo == UseNextMarking we cannot currently do a sanity
3175           // check on the live bytes as the calculation has not been
3176           // finalized yet.
3177         }
3178       }
3179     }
3180     return false; // stop the region iteration if we hit a failure
3181   }
3182 };
3183 
3184 // This is the task used for parallel verification of the heap regions
3185 
3186 class G1ParVerifyTask: public AbstractGangTask {
3187 private:
3188   G1CollectedHeap*  _g1h;
3189   VerifyOption      _vo;
3190   bool              _failures;
3191   HeapRegionClaimer _hrclaimer;
3192 
3193 public:
3194   // _vo == UsePrevMarking -> use "prev" marking information,
3195   // _vo == UseNextMarking -> use "next" marking information,
3196   // _vo == UseMarkWord    -> use mark word from object header.
3197   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3198       AbstractGangTask("Parallel verify task"),
3199       _g1h(g1h),
3200       _vo(vo),
3201       _failures(false),
3202       _hrclaimer(g1h->workers()->active_workers()) {}
3203 
3204   bool failures() {
3205     return _failures;
3206   }
3207 
3208   void work(uint worker_id) {
3209     HandleMark hm;
3210     VerifyRegionClosure blk(true, _vo);
3211     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3212     if (blk.failures()) {
3213       _failures = true;
3214     }
3215   }
3216 };
3217 
3218 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3219   if (SafepointSynchronize::is_at_safepoint()) {
3220     assert(Thread::current()->is_VM_thread(),
3221            "Expected to be executed serially by the VM thread at this point");
3222 
3223     if (!silent) { gclog_or_tty->print("Roots "); }
3224     VerifyRootsClosure rootsCl(vo);
3225     VerifyKlassClosure klassCl(this, &rootsCl);
3226     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3227 
3228     // We apply the relevant closures to all the oops in the
3229     // system dictionary, class loader data graph, the string table
3230     // and the nmethods in the code cache.
3231     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3232     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3233 
3234     {
3235       G1RootProcessor root_processor(this, 1);
3236       root_processor.process_all_roots(&rootsCl,
3237                                        &cldCl,
3238                                        &blobsCl);
3239     }
3240 
3241     bool failures = rootsCl.failures() || codeRootsCl.failures();
3242 
3243     if (vo != VerifyOption_G1UseMarkWord) {
3244       // If we're verifying during a full GC then the region sets
3245       // will have been torn down at the start of the GC. Therefore
3246       // verifying the region sets will fail. So we only verify
3247       // the region sets when not in a full GC.
3248       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3249       verify_region_sets();
3250     }
3251 
3252     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3253     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3254 
3255       G1ParVerifyTask task(this, vo);
3256       workers()->run_task(&task);
3257       if (task.failures()) {
3258         failures = true;
3259       }
3260 
3261     } else {
3262       VerifyRegionClosure blk(false, vo);
3263       heap_region_iterate(&blk);
3264       if (blk.failures()) {
3265         failures = true;
3266       }
3267     }
3268 
3269     if (G1StringDedup::is_enabled()) {
3270       if (!silent) gclog_or_tty->print("StrDedup ");
3271       G1StringDedup::verify();
3272     }
3273 
3274     if (failures) {
3275       gclog_or_tty->print_cr("Heap:");
3276       // It helps to have the per-region information in the output to
3277       // help us track down what went wrong. This is why we call
3278       // print_extended_on() instead of print_on().
3279       print_extended_on(gclog_or_tty);
3280       gclog_or_tty->cr();
3281       gclog_or_tty->flush();
3282     }
3283     guarantee(!failures, "there should not have been any failures");
3284   } else {
3285     if (!silent) {
3286       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3287       if (G1StringDedup::is_enabled()) {
3288         gclog_or_tty->print(", StrDedup");
3289       }
3290       gclog_or_tty->print(") ");
3291     }
3292   }
3293 }
3294 
3295 void G1CollectedHeap::verify(bool silent) {
3296   verify(silent, VerifyOption_G1UsePrevMarking);
3297 }
3298 
3299 double G1CollectedHeap::verify(bool guard, const char* msg) {
3300   double verify_time_ms = 0.0;
3301 
3302   if (guard && total_collections() >= VerifyGCStartAt) {
3303     double verify_start = os::elapsedTime();
3304     HandleMark hm;  // Discard invalid handles created during verification
3305     prepare_for_verify();
3306     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3307     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3308   }
3309 
3310   return verify_time_ms;
3311 }
3312 
3313 void G1CollectedHeap::verify_before_gc() {
3314   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3315   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3316 }
3317 
3318 void G1CollectedHeap::verify_after_gc() {
3319   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3320   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3321 }
3322 
3323 class PrintRegionClosure: public HeapRegionClosure {
3324   outputStream* _st;
3325 public:
3326   PrintRegionClosure(outputStream* st) : _st(st) {}
3327   bool doHeapRegion(HeapRegion* r) {
3328     r->print_on(_st);
3329     return false;
3330   }
3331 };
3332 
3333 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3334                                        const HeapRegion* hr,
3335                                        const VerifyOption vo) const {
3336   switch (vo) {
3337   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3338   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3339   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3340   default:                            ShouldNotReachHere();
3341   }
3342   return false; // keep some compilers happy
3343 }
3344 
3345 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3346                                        const VerifyOption vo) const {
3347   switch (vo) {
3348   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3349   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3350   case VerifyOption_G1UseMarkWord: {
3351     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3352     return !obj->is_gc_marked() && !hr->is_archive();
3353   }
3354   default:                            ShouldNotReachHere();
3355   }
3356   return false; // keep some compilers happy
3357 }
3358 
3359 void G1CollectedHeap::print_on(outputStream* st) const {
3360   st->print(" %-20s", "garbage-first heap");
3361   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3362             capacity()/K, used_unlocked()/K);
3363   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3364             p2i(_hrm.reserved().start()),
3365             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3366             p2i(_hrm.reserved().end()));
3367   st->cr();
3368   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3369   uint young_regions = _young_list->length();
3370   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3371             (size_t) young_regions * HeapRegion::GrainBytes / K);
3372   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3373   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3374             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3375   st->cr();
3376   MetaspaceAux::print_on(st);
3377 }
3378 
3379 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3380   print_on(st);
3381 
3382   // Print the per-region information.
3383   st->cr();
3384   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3385                "HS=humongous(starts), HC=humongous(continues), "
3386                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3387                "PTAMS=previous top-at-mark-start, "
3388                "NTAMS=next top-at-mark-start)");
3389   PrintRegionClosure blk(st);
3390   heap_region_iterate(&blk);
3391 }
3392 
3393 void G1CollectedHeap::print_on_error(outputStream* st) const {
3394   this->CollectedHeap::print_on_error(st);
3395 
3396   if (_cm != NULL) {
3397     st->cr();
3398     _cm->print_on_error(st);
3399   }
3400 }
3401 
3402 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3403   workers()->print_worker_threads_on(st);
3404   _cmThread->print_on(st);
3405   st->cr();
3406   _cm->print_worker_threads_on(st);
3407   _cg1r->print_worker_threads_on(st);
3408   if (G1StringDedup::is_enabled()) {
3409     G1StringDedup::print_worker_threads_on(st);
3410   }
3411 }
3412 
3413 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3414   workers()->threads_do(tc);
3415   tc->do_thread(_cmThread);
3416   _cg1r->threads_do(tc);
3417   if (G1StringDedup::is_enabled()) {
3418     G1StringDedup::threads_do(tc);
3419   }
3420 }
3421 
3422 void G1CollectedHeap::print_tracing_info() const {
3423   // We'll overload this to mean "trace GC pause statistics."
3424   if (TraceYoungGenTime || TraceOldGenTime) {
3425     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3426     // to that.
3427     g1_policy()->print_tracing_info();
3428   }
3429   if (G1SummarizeRSetStats) {
3430     g1_rem_set()->print_summary_info();
3431   }
3432   if (G1SummarizeConcMark) {
3433     concurrent_mark()->print_summary_info();
3434   }
3435   g1_policy()->print_yg_surv_rate_info();
3436 }
3437 
3438 #ifndef PRODUCT
3439 // Helpful for debugging RSet issues.
3440 
3441 class PrintRSetsClosure : public HeapRegionClosure {
3442 private:
3443   const char* _msg;
3444   size_t _occupied_sum;
3445 
3446 public:
3447   bool doHeapRegion(HeapRegion* r) {
3448     HeapRegionRemSet* hrrs = r->rem_set();
3449     size_t occupied = hrrs->occupied();
3450     _occupied_sum += occupied;
3451 
3452     gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3453                            HR_FORMAT_PARAMS(r));
3454     if (occupied == 0) {
3455       gclog_or_tty->print_cr("  RSet is empty");
3456     } else {
3457       hrrs->print();
3458     }
3459     gclog_or_tty->print_cr("----------");
3460     return false;
3461   }
3462 
3463   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3464     gclog_or_tty->cr();
3465     gclog_or_tty->print_cr("========================================");
3466     gclog_or_tty->print_cr("%s", msg);
3467     gclog_or_tty->cr();
3468   }
3469 
3470   ~PrintRSetsClosure() {
3471     gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3472     gclog_or_tty->print_cr("========================================");
3473     gclog_or_tty->cr();
3474   }
3475 };
3476 
3477 void G1CollectedHeap::print_cset_rsets() {
3478   PrintRSetsClosure cl("Printing CSet RSets");
3479   collection_set_iterate(&cl);
3480 }
3481 
3482 void G1CollectedHeap::print_all_rsets() {
3483   PrintRSetsClosure cl("Printing All RSets");;
3484   heap_region_iterate(&cl);
3485 }
3486 #endif // PRODUCT
3487 
3488 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3489   YoungList* young_list = heap()->young_list();
3490 
3491   size_t eden_used_bytes = young_list->eden_used_bytes();
3492   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3493 
3494   size_t eden_capacity_bytes =
3495     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3496 
3497   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3498   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3499 }
3500 
3501 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3502   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3503   gc_tracer->report_gc_heap_summary(when, heap_summary);
3504 
3505   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3506   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3507 }
3508 
3509 
3510 G1CollectedHeap* G1CollectedHeap::heap() {
3511   CollectedHeap* heap = Universe::heap();
3512   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3513   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3514   return (G1CollectedHeap*)heap;
3515 }
3516 
3517 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3518   // always_do_update_barrier = false;
3519   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3520   // Fill TLAB's and such
3521   accumulate_statistics_all_tlabs();
3522   ensure_parsability(true);
3523 
3524   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3525       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3526     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3527   }
3528 }
3529 
3530 void G1CollectedHeap::gc_epilogue(bool full) {
3531 
3532   if (G1SummarizeRSetStats &&
3533       (G1SummarizeRSetStatsPeriod > 0) &&
3534       // we are at the end of the GC. Total collections has already been increased.
3535       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3536     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3537   }
3538 
3539   // FIXME: what is this about?
3540   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3541   // is set.
3542   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3543                         "derived pointer present"));
3544   // always_do_update_barrier = true;
3545 
3546   resize_all_tlabs();
3547   allocation_context_stats().update(full);
3548 
3549   // We have just completed a GC. Update the soft reference
3550   // policy with the new heap occupancy
3551   Universe::update_heap_info_at_gc();
3552 }
3553 
3554 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3555                                                uint gc_count_before,
3556                                                bool* succeeded,
3557                                                GCCause::Cause gc_cause) {
3558   assert_heap_not_locked_and_not_at_safepoint();
3559   g1_policy()->record_stop_world_start();
3560   VM_G1IncCollectionPause op(gc_count_before,
3561                              word_size,
3562                              false, /* should_initiate_conc_mark */
3563                              g1_policy()->max_pause_time_ms(),
3564                              gc_cause);
3565 
3566   op.set_allocation_context(AllocationContext::current());
3567   VMThread::execute(&op);
3568 
3569   HeapWord* result = op.result();
3570   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3571   assert(result == NULL || ret_succeeded,
3572          "the result should be NULL if the VM did not succeed");
3573   *succeeded = ret_succeeded;
3574 
3575   assert_heap_not_locked();
3576   return result;
3577 }
3578 
3579 void
3580 G1CollectedHeap::doConcurrentMark() {
3581   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3582   if (!_cmThread->in_progress()) {
3583     _cmThread->set_started();
3584     CGC_lock->notify();
3585   }
3586 }
3587 
3588 size_t G1CollectedHeap::pending_card_num() {
3589   size_t extra_cards = 0;
3590   JavaThread *curr = Threads::first();
3591   while (curr != NULL) {
3592     DirtyCardQueue& dcq = curr->dirty_card_queue();
3593     extra_cards += dcq.size();
3594     curr = curr->next();
3595   }
3596   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3597   size_t buffer_size = dcqs.buffer_size();
3598   size_t buffer_num = dcqs.completed_buffers_num();
3599 
3600   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3601   // in bytes - not the number of 'entries'. We need to convert
3602   // into a number of cards.
3603   return (buffer_size * buffer_num + extra_cards) / oopSize;
3604 }
3605 
3606 size_t G1CollectedHeap::cards_scanned() {
3607   return g1_rem_set()->cardsScanned();
3608 }
3609 
3610 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3611  private:
3612   size_t _total_humongous;
3613   size_t _candidate_humongous;
3614 
3615   DirtyCardQueue _dcq;
3616 
3617   // We don't nominate objects with many remembered set entries, on
3618   // the assumption that such objects are likely still live.
3619   bool is_remset_small(HeapRegion* region) const {
3620     HeapRegionRemSet* const rset = region->rem_set();
3621     return G1EagerReclaimHumongousObjectsWithStaleRefs
3622       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3623       : rset->is_empty();
3624   }
3625 
3626   bool is_typeArray_region(HeapRegion* region) const {
3627     return oop(region->bottom())->is_typeArray();
3628   }
3629 
3630   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3631     assert(region->is_starts_humongous(), "Must start a humongous object");
3632 
3633     // Candidate selection must satisfy the following constraints
3634     // while concurrent marking is in progress:
3635     //
3636     // * In order to maintain SATB invariants, an object must not be
3637     // reclaimed if it was allocated before the start of marking and
3638     // has not had its references scanned.  Such an object must have
3639     // its references (including type metadata) scanned to ensure no
3640     // live objects are missed by the marking process.  Objects
3641     // allocated after the start of concurrent marking don't need to
3642     // be scanned.
3643     //
3644     // * An object must not be reclaimed if it is on the concurrent
3645     // mark stack.  Objects allocated after the start of concurrent
3646     // marking are never pushed on the mark stack.
3647     //
3648     // Nominating only objects allocated after the start of concurrent
3649     // marking is sufficient to meet both constraints.  This may miss
3650     // some objects that satisfy the constraints, but the marking data
3651     // structures don't support efficiently performing the needed
3652     // additional tests or scrubbing of the mark stack.
3653     //
3654     // However, we presently only nominate is_typeArray() objects.
3655     // A humongous object containing references induces remembered
3656     // set entries on other regions.  In order to reclaim such an
3657     // object, those remembered sets would need to be cleaned up.
3658     //
3659     // We also treat is_typeArray() objects specially, allowing them
3660     // to be reclaimed even if allocated before the start of
3661     // concurrent mark.  For this we rely on mark stack insertion to
3662     // exclude is_typeArray() objects, preventing reclaiming an object
3663     // that is in the mark stack.  We also rely on the metadata for
3664     // such objects to be built-in and so ensured to be kept live.
3665     // Frequent allocation and drop of large binary blobs is an
3666     // important use case for eager reclaim, and this special handling
3667     // may reduce needed headroom.
3668 
3669     return is_typeArray_region(region) && is_remset_small(region);
3670   }
3671 
3672  public:
3673   RegisterHumongousWithInCSetFastTestClosure()
3674   : _total_humongous(0),
3675     _candidate_humongous(0),
3676     _dcq(&JavaThread::dirty_card_queue_set()) {
3677   }
3678 
3679   virtual bool doHeapRegion(HeapRegion* r) {
3680     if (!r->is_starts_humongous()) {
3681       return false;
3682     }
3683     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3684 
3685     bool is_candidate = humongous_region_is_candidate(g1h, r);
3686     uint rindex = r->hrm_index();
3687     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3688     if (is_candidate) {
3689       _candidate_humongous++;
3690       g1h->register_humongous_region_with_cset(rindex);
3691       // Is_candidate already filters out humongous object with large remembered sets.
3692       // If we have a humongous object with a few remembered sets, we simply flush these
3693       // remembered set entries into the DCQS. That will result in automatic
3694       // re-evaluation of their remembered set entries during the following evacuation
3695       // phase.
3696       if (!r->rem_set()->is_empty()) {
3697         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3698                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3699         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3700         HeapRegionRemSetIterator hrrs(r->rem_set());
3701         size_t card_index;
3702         while (hrrs.has_next(card_index)) {
3703           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3704           // The remembered set might contain references to already freed
3705           // regions. Filter out such entries to avoid failing card table
3706           // verification.
3707           if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3708             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3709               *card_ptr = CardTableModRefBS::dirty_card_val();
3710               _dcq.enqueue(card_ptr);
3711             }
3712           }
3713         }
3714         r->rem_set()->clear_locked();
3715       }
3716       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3717     }
3718     _total_humongous++;
3719 
3720     return false;
3721   }
3722 
3723   size_t total_humongous() const { return _total_humongous; }
3724   size_t candidate_humongous() const { return _candidate_humongous; }
3725 
3726   void flush_rem_set_entries() { _dcq.flush(); }
3727 };
3728 
3729 void G1CollectedHeap::register_humongous_regions_with_cset() {
3730   if (!G1EagerReclaimHumongousObjects) {
3731     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3732     return;
3733   }
3734   double time = os::elapsed_counter();
3735 
3736   // Collect reclaim candidate information and register candidates with cset.
3737   RegisterHumongousWithInCSetFastTestClosure cl;
3738   heap_region_iterate(&cl);
3739 
3740   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3741   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3742                                                                   cl.total_humongous(),
3743                                                                   cl.candidate_humongous());
3744   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3745 
3746   // Finally flush all remembered set entries to re-check into the global DCQS.
3747   cl.flush_rem_set_entries();
3748 }
3749 
3750 void
3751 G1CollectedHeap::setup_surviving_young_words() {
3752   assert(_surviving_young_words == NULL, "pre-condition");
3753   uint array_length = g1_policy()->young_cset_region_length();
3754   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3755   if (_surviving_young_words == NULL) {
3756     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3757                           "Not enough space for young surv words summary.");
3758   }
3759   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3760 #ifdef ASSERT
3761   for (uint i = 0;  i < array_length; ++i) {
3762     assert( _surviving_young_words[i] == 0, "memset above" );
3763   }
3764 #endif // !ASSERT
3765 }
3766 
3767 void
3768 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3769   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3770   uint array_length = g1_policy()->young_cset_region_length();
3771   for (uint i = 0; i < array_length; ++i) {
3772     _surviving_young_words[i] += surv_young_words[i];
3773   }
3774 }
3775 
3776 void
3777 G1CollectedHeap::cleanup_surviving_young_words() {
3778   guarantee( _surviving_young_words != NULL, "pre-condition" );
3779   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3780   _surviving_young_words = NULL;
3781 }
3782 
3783 #ifdef ASSERT
3784 class VerifyCSetClosure: public HeapRegionClosure {
3785 public:
3786   bool doHeapRegion(HeapRegion* hr) {
3787     // Here we check that the CSet region's RSet is ready for parallel
3788     // iteration. The fields that we'll verify are only manipulated
3789     // when the region is part of a CSet and is collected. Afterwards,
3790     // we reset these fields when we clear the region's RSet (when the
3791     // region is freed) so they are ready when the region is
3792     // re-allocated. The only exception to this is if there's an
3793     // evacuation failure and instead of freeing the region we leave
3794     // it in the heap. In that case, we reset these fields during
3795     // evacuation failure handling.
3796     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3797 
3798     // Here's a good place to add any other checks we'd like to
3799     // perform on CSet regions.
3800     return false;
3801   }
3802 };
3803 #endif // ASSERT
3804 
3805 uint G1CollectedHeap::num_task_queues() const {
3806   return _task_queues->size();
3807 }
3808 
3809 #if TASKQUEUE_STATS
3810 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3811   st->print_raw_cr("GC Task Stats");
3812   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3813   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3814 }
3815 
3816 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3817   print_taskqueue_stats_hdr(st);
3818 
3819   TaskQueueStats totals;
3820   const uint n = num_task_queues();
3821   for (uint i = 0; i < n; ++i) {
3822     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3823     totals += task_queue(i)->stats;
3824   }
3825   st->print_raw("tot "); totals.print(st); st->cr();
3826 
3827   DEBUG_ONLY(totals.verify());
3828 }
3829 
3830 void G1CollectedHeap::reset_taskqueue_stats() {
3831   const uint n = num_task_queues();
3832   for (uint i = 0; i < n; ++i) {
3833     task_queue(i)->stats.reset();
3834   }
3835 }
3836 #endif // TASKQUEUE_STATS
3837 
3838 void G1CollectedHeap::log_gc_header() {
3839   if (!G1Log::fine()) {
3840     return;
3841   }
3842 
3843   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3844 
3845   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3846     .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3847     .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3848 
3849   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3850 }
3851 
3852 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3853   if (!G1Log::fine()) {
3854     return;
3855   }
3856 
3857   if (G1Log::finer()) {
3858     if (evacuation_failed()) {
3859       gclog_or_tty->print(" (to-space exhausted)");
3860     }
3861     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3862     g1_policy()->phase_times()->note_gc_end();
3863     g1_policy()->phase_times()->print(pause_time_sec);
3864     g1_policy()->print_detailed_heap_transition();
3865   } else {
3866     if (evacuation_failed()) {
3867       gclog_or_tty->print("--");
3868     }
3869     g1_policy()->print_heap_transition();
3870     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3871   }
3872   gclog_or_tty->flush();
3873 }
3874 
3875 void G1CollectedHeap::wait_for_root_region_scanning() {
3876   double scan_wait_start = os::elapsedTime();
3877   // We have to wait until the CM threads finish scanning the
3878   // root regions as it's the only way to ensure that all the
3879   // objects on them have been correctly scanned before we start
3880   // moving them during the GC.
3881   bool waited = _cm->root_regions()->wait_until_scan_finished();
3882   double wait_time_ms = 0.0;
3883   if (waited) {
3884     double scan_wait_end = os::elapsedTime();
3885     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3886   }
3887   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3888 }
3889 
3890 bool
3891 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3892   assert_at_safepoint(true /* should_be_vm_thread */);
3893   guarantee(!is_gc_active(), "collection is not reentrant");
3894 
3895   if (GC_locker::check_active_before_gc()) {
3896     return false;
3897   }
3898 
3899   _gc_timer_stw->register_gc_start();
3900 
3901   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3902 
3903   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3904   ResourceMark rm;
3905 
3906   wait_for_root_region_scanning();
3907 
3908   G1Log::update_level();
3909   print_heap_before_gc();
3910   trace_heap_before_gc(_gc_tracer_stw);
3911 
3912   verify_region_sets_optional();
3913   verify_dirty_young_regions();
3914 
3915   // This call will decide whether this pause is an initial-mark
3916   // pause. If it is, during_initial_mark_pause() will return true
3917   // for the duration of this pause.
3918   g1_policy()->decide_on_conc_mark_initiation();
3919 
3920   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3921   assert(!collector_state()->during_initial_mark_pause() ||
3922           collector_state()->gcs_are_young(), "sanity");
3923 
3924   // We also do not allow mixed GCs during marking.
3925   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3926 
3927   // Record whether this pause is an initial mark. When the current
3928   // thread has completed its logging output and it's safe to signal
3929   // the CM thread, the flag's value in the policy has been reset.
3930   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3931 
3932   // Inner scope for scope based logging, timers, and stats collection
3933   {
3934     EvacuationInfo evacuation_info;
3935 
3936     if (collector_state()->during_initial_mark_pause()) {
3937       // We are about to start a marking cycle, so we increment the
3938       // full collection counter.
3939       increment_old_marking_cycles_started();
3940       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3941     }
3942 
3943     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3944 
3945     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3946 
3947     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3948                                                                   workers()->active_workers(),
3949                                                                   Threads::number_of_non_daemon_threads());
3950     workers()->set_active_workers(active_workers);
3951 
3952     double pause_start_sec = os::elapsedTime();
3953     g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
3954     log_gc_header();
3955 
3956     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3957     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3958 
3959     // If the secondary_free_list is not empty, append it to the
3960     // free_list. No need to wait for the cleanup operation to finish;
3961     // the region allocation code will check the secondary_free_list
3962     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3963     // set, skip this step so that the region allocation code has to
3964     // get entries from the secondary_free_list.
3965     if (!G1StressConcRegionFreeing) {
3966       append_secondary_free_list_if_not_empty_with_lock();
3967     }
3968 
3969     assert(check_young_list_well_formed(), "young list should be well formed");
3970 
3971     // Don't dynamically change the number of GC threads this early.  A value of
3972     // 0 is used to indicate serial work.  When parallel work is done,
3973     // it will be set.
3974 
3975     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3976       IsGCActiveMark x;
3977 
3978       gc_prologue(false);
3979       increment_total_collections(false /* full gc */);
3980       increment_gc_time_stamp();
3981 
3982       verify_before_gc();
3983 
3984       check_bitmaps("GC Start");
3985 
3986       COMPILER2_PRESENT(DerivedPointerTable::clear());
3987 
3988       // Please see comment in g1CollectedHeap.hpp and
3989       // G1CollectedHeap::ref_processing_init() to see how
3990       // reference processing currently works in G1.
3991 
3992       // Enable discovery in the STW reference processor
3993       ref_processor_stw()->enable_discovery();
3994 
3995       {
3996         // We want to temporarily turn off discovery by the
3997         // CM ref processor, if necessary, and turn it back on
3998         // on again later if we do. Using a scoped
3999         // NoRefDiscovery object will do this.
4000         NoRefDiscovery no_cm_discovery(ref_processor_cm());
4001 
4002         // Forget the current alloc region (we might even choose it to be part
4003         // of the collection set!).
4004         _allocator->release_mutator_alloc_region();
4005 
4006         // We should call this after we retire the mutator alloc
4007         // region(s) so that all the ALLOC / RETIRE events are generated
4008         // before the start GC event.
4009         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4010 
4011         // This timing is only used by the ergonomics to handle our pause target.
4012         // It is unclear why this should not include the full pause. We will
4013         // investigate this in CR 7178365.
4014         //
4015         // Preserving the old comment here if that helps the investigation:
4016         //
4017         // The elapsed time induced by the start time below deliberately elides
4018         // the possible verification above.
4019         double sample_start_time_sec = os::elapsedTime();
4020 
4021 #if YOUNG_LIST_VERBOSE
4022         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4023         _young_list->print();
4024         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4025 #endif // YOUNG_LIST_VERBOSE
4026 
4027         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4028 
4029 #if YOUNG_LIST_VERBOSE
4030         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4031         _young_list->print();
4032 #endif // YOUNG_LIST_VERBOSE
4033 
4034         if (collector_state()->during_initial_mark_pause()) {
4035           concurrent_mark()->checkpointRootsInitialPre();
4036         }
4037 
4038 #if YOUNG_LIST_VERBOSE
4039         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4040         _young_list->print();
4041         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4042 #endif // YOUNG_LIST_VERBOSE
4043 
4044         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4045 
4046         register_humongous_regions_with_cset();
4047 
4048         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4049 
4050         _cm->note_start_of_gc();
4051         // We call this after finalize_cset() to
4052         // ensure that the CSet has been finalized.
4053         _cm->verify_no_cset_oops();
4054 
4055         if (_hr_printer.is_active()) {
4056           HeapRegion* hr = g1_policy()->collection_set();
4057           while (hr != NULL) {
4058             _hr_printer.cset(hr);
4059             hr = hr->next_in_collection_set();
4060           }
4061         }
4062 
4063 #ifdef ASSERT
4064         VerifyCSetClosure cl;
4065         collection_set_iterate(&cl);
4066 #endif // ASSERT
4067 
4068         setup_surviving_young_words();
4069 
4070         // Initialize the GC alloc regions.
4071         _allocator->init_gc_alloc_regions(evacuation_info);
4072 
4073         // Actually do the work...
4074         evacuate_collection_set(evacuation_info);
4075 
4076         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4077 
4078         eagerly_reclaim_humongous_regions();
4079 
4080         g1_policy()->clear_collection_set();
4081 
4082         cleanup_surviving_young_words();
4083 
4084         // Start a new incremental collection set for the next pause.
4085         g1_policy()->start_incremental_cset_building();
4086 
4087         clear_cset_fast_test();
4088 
4089         _young_list->reset_sampled_info();
4090 
4091         // Don't check the whole heap at this point as the
4092         // GC alloc regions from this pause have been tagged
4093         // as survivors and moved on to the survivor list.
4094         // Survivor regions will fail the !is_young() check.
4095         assert(check_young_list_empty(false /* check_heap */),
4096           "young list should be empty");
4097 
4098 #if YOUNG_LIST_VERBOSE
4099         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4100         _young_list->print();
4101 #endif // YOUNG_LIST_VERBOSE
4102 
4103         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4104                                              _young_list->first_survivor_region(),
4105                                              _young_list->last_survivor_region());
4106 
4107         _young_list->reset_auxilary_lists();
4108 
4109         if (evacuation_failed()) {
4110           set_used(recalculate_used());
4111           if (_archive_allocator != NULL) {
4112             _archive_allocator->clear_used();
4113           }
4114           for (uint i = 0; i < ParallelGCThreads; i++) {
4115             if (_evacuation_failed_info_array[i].has_failed()) {
4116               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4117             }
4118           }
4119         } else {
4120           // The "used" of the the collection set have already been subtracted
4121           // when they were freed.  Add in the bytes evacuated.
4122           increase_used(g1_policy()->bytes_copied_during_gc());
4123         }
4124 
4125         if (collector_state()->during_initial_mark_pause()) {
4126           // We have to do this before we notify the CM threads that
4127           // they can start working to make sure that all the
4128           // appropriate initialization is done on the CM object.
4129           concurrent_mark()->checkpointRootsInitialPost();
4130           collector_state()->set_mark_in_progress(true);
4131           // Note that we don't actually trigger the CM thread at
4132           // this point. We do that later when we're sure that
4133           // the current thread has completed its logging output.
4134         }
4135 
4136         allocate_dummy_regions();
4137 
4138 #if YOUNG_LIST_VERBOSE
4139         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4140         _young_list->print();
4141         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4142 #endif // YOUNG_LIST_VERBOSE
4143 
4144         _allocator->init_mutator_alloc_region();
4145 
4146         {
4147           size_t expand_bytes = g1_policy()->expansion_amount();
4148           if (expand_bytes > 0) {
4149             size_t bytes_before = capacity();
4150             // No need for an ergo verbose message here,
4151             // expansion_amount() does this when it returns a value > 0.
4152             if (!expand(expand_bytes)) {
4153               // We failed to expand the heap. Cannot do anything about it.
4154             }
4155           }
4156         }
4157 
4158         // We redo the verification but now wrt to the new CSet which
4159         // has just got initialized after the previous CSet was freed.
4160         _cm->verify_no_cset_oops();
4161         _cm->note_end_of_gc();
4162 
4163         // This timing is only used by the ergonomics to handle our pause target.
4164         // It is unclear why this should not include the full pause. We will
4165         // investigate this in CR 7178365.
4166         double sample_end_time_sec = os::elapsedTime();
4167         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4168         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4169 
4170         MemoryService::track_memory_usage();
4171 
4172         // In prepare_for_verify() below we'll need to scan the deferred
4173         // update buffers to bring the RSets up-to-date if
4174         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4175         // the update buffers we'll probably need to scan cards on the
4176         // regions we just allocated to (i.e., the GC alloc
4177         // regions). However, during the last GC we called
4178         // set_saved_mark() on all the GC alloc regions, so card
4179         // scanning might skip the [saved_mark_word()...top()] area of
4180         // those regions (i.e., the area we allocated objects into
4181         // during the last GC). But it shouldn't. Given that
4182         // saved_mark_word() is conditional on whether the GC time stamp
4183         // on the region is current or not, by incrementing the GC time
4184         // stamp here we invalidate all the GC time stamps on all the
4185         // regions and saved_mark_word() will simply return top() for
4186         // all the regions. This is a nicer way of ensuring this rather
4187         // than iterating over the regions and fixing them. In fact, the
4188         // GC time stamp increment here also ensures that
4189         // saved_mark_word() will return top() between pauses, i.e.,
4190         // during concurrent refinement. So we don't need the
4191         // is_gc_active() check to decided which top to use when
4192         // scanning cards (see CR 7039627).
4193         increment_gc_time_stamp();
4194 
4195         verify_after_gc();
4196         check_bitmaps("GC End");
4197 
4198         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4199         ref_processor_stw()->verify_no_references_recorded();
4200 
4201         // CM reference discovery will be re-enabled if necessary.
4202       }
4203 
4204       // We should do this after we potentially expand the heap so
4205       // that all the COMMIT events are generated before the end GC
4206       // event, and after we retire the GC alloc regions so that all
4207       // RETIRE events are generated before the end GC event.
4208       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4209 
4210 #ifdef TRACESPINNING
4211       ParallelTaskTerminator::print_termination_counts();
4212 #endif
4213 
4214       gc_epilogue(false);
4215     }
4216 
4217     // Print the remainder of the GC log output.
4218     log_gc_footer(os::elapsedTime() - pause_start_sec);
4219 
4220     // It is not yet to safe to tell the concurrent mark to
4221     // start as we have some optional output below. We don't want the
4222     // output from the concurrent mark thread interfering with this
4223     // logging output either.
4224 
4225     _hrm.verify_optional();
4226     verify_region_sets_optional();
4227 
4228     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4229     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4230 
4231     print_heap_after_gc();
4232     trace_heap_after_gc(_gc_tracer_stw);
4233 
4234     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4235     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4236     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4237     // before any GC notifications are raised.
4238     g1mm()->update_sizes();
4239 
4240     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4241     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4242     _gc_timer_stw->register_gc_end();
4243     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4244   }
4245   // It should now be safe to tell the concurrent mark thread to start
4246   // without its logging output interfering with the logging output
4247   // that came from the pause.
4248 
4249   if (should_start_conc_mark) {
4250     // CAUTION: after the doConcurrentMark() call below,
4251     // the concurrent marking thread(s) could be running
4252     // concurrently with us. Make sure that anything after
4253     // this point does not assume that we are the only GC thread
4254     // running. Note: of course, the actual marking work will
4255     // not start until the safepoint itself is released in
4256     // SuspendibleThreadSet::desynchronize().
4257     doConcurrentMark();
4258   }
4259 
4260   return true;
4261 }
4262 
4263 void G1CollectedHeap::remove_self_forwarding_pointers() {
4264   double remove_self_forwards_start = os::elapsedTime();
4265 
4266   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4267   workers()->run_task(&rsfp_task);
4268 
4269   // Now restore saved marks, if any.
4270   for (uint i = 0; i < ParallelGCThreads; i++) {
4271     OopAndMarkOopStack& cur = _preserved_objs[i];
4272     while (!cur.is_empty()) {
4273       OopAndMarkOop elem = cur.pop();
4274       elem.set_mark();
4275     }
4276     cur.clear(true);
4277   }
4278 
4279   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4280 }
4281 
4282 void G1CollectedHeap::preserve_mark_during_evac_failure(uint queue_num, oop obj, markOop m) {
4283   if (!_evacuation_failed) {
4284     _evacuation_failed = true;
4285   }
4286 
4287   _evacuation_failed_info_array[queue_num].register_copy_failure(obj->size());
4288 
4289   // We want to call the "for_promotion_failure" version only in the
4290   // case of a promotion failure.
4291   if (m->must_be_preserved_for_promotion_failure(obj)) {
4292     OopAndMarkOop elem(obj, m);
4293     _preserved_objs[queue_num].push(elem);
4294   }
4295 }
4296 
4297 void G1ParCopyHelper::mark_object(oop obj) {
4298   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4299 
4300   // We know that the object is not moving so it's safe to read its size.
4301   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4302 }
4303 
4304 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4305   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4306   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4307   assert(from_obj != to_obj, "should not be self-forwarded");
4308 
4309   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4310   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4311 
4312   // The object might be in the process of being copied by another
4313   // worker so we cannot trust that its to-space image is
4314   // well-formed. So we have to read its size from its from-space
4315   // image which we know should not be changing.
4316   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4317 }
4318 
4319 template <class T>
4320 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4321   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4322     _scanned_klass->record_modified_oops();
4323   }
4324 }
4325 
4326 template <G1Barrier barrier, G1Mark do_mark_object>
4327 template <class T>
4328 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4329   T heap_oop = oopDesc::load_heap_oop(p);
4330 
4331   if (oopDesc::is_null(heap_oop)) {
4332     return;
4333   }
4334 
4335   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4336 
4337   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4338 
4339   const InCSetState state = _g1->in_cset_state(obj);
4340   if (state.is_in_cset()) {
4341     oop forwardee;
4342     markOop m = obj->mark();
4343     if (m->is_marked()) {
4344       forwardee = (oop) m->decode_pointer();
4345     } else {
4346       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4347     }
4348     assert(forwardee != NULL, "forwardee should not be NULL");
4349     oopDesc::encode_store_heap_oop(p, forwardee);
4350     if (do_mark_object != G1MarkNone && forwardee != obj) {
4351       // If the object is self-forwarded we don't need to explicitly
4352       // mark it, the evacuation failure protocol will do so.
4353       mark_forwarded_object(obj, forwardee);
4354     }
4355 
4356     if (barrier == G1BarrierKlass) {
4357       do_klass_barrier(p, forwardee);
4358     }
4359   } else {
4360     if (state.is_humongous()) {
4361       _g1->set_humongous_is_live(obj);
4362     }
4363     // The object is not in collection set. If we're a root scanning
4364     // closure during an initial mark pause then attempt to mark the object.
4365     if (do_mark_object == G1MarkFromRoot) {
4366       mark_object(obj);
4367     }
4368   }
4369 }
4370 
4371 class G1ParEvacuateFollowersClosure : public VoidClosure {
4372 protected:
4373   G1CollectedHeap*              _g1h;
4374   G1ParScanThreadState*         _par_scan_state;
4375   RefToScanQueueSet*            _queues;
4376   ParallelTaskTerminator*       _terminator;
4377 
4378   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4379   RefToScanQueueSet*      queues()         { return _queues; }
4380   ParallelTaskTerminator* terminator()     { return _terminator; }
4381 
4382 public:
4383   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4384                                 G1ParScanThreadState* par_scan_state,
4385                                 RefToScanQueueSet* queues,
4386                                 ParallelTaskTerminator* terminator)
4387     : _g1h(g1h), _par_scan_state(par_scan_state),
4388       _queues(queues), _terminator(terminator) {}
4389 
4390   void do_void();
4391 
4392 private:
4393   inline bool offer_termination();
4394 };
4395 
4396 bool G1ParEvacuateFollowersClosure::offer_termination() {
4397   G1ParScanThreadState* const pss = par_scan_state();
4398   pss->start_term_time();
4399   const bool res = terminator()->offer_termination();
4400   pss->end_term_time();
4401   return res;
4402 }
4403 
4404 void G1ParEvacuateFollowersClosure::do_void() {
4405   G1ParScanThreadState* const pss = par_scan_state();
4406   pss->trim_queue();
4407   do {
4408     pss->steal_and_trim_queue(queues());
4409   } while (!offer_termination());
4410 }
4411 
4412 class G1KlassScanClosure : public KlassClosure {
4413  G1ParCopyHelper* _closure;
4414  bool             _process_only_dirty;
4415  int              _count;
4416  public:
4417   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4418       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4419   void do_klass(Klass* klass) {
4420     // If the klass has not been dirtied we know that there's
4421     // no references into  the young gen and we can skip it.
4422    if (!_process_only_dirty || klass->has_modified_oops()) {
4423       // Clean the klass since we're going to scavenge all the metadata.
4424       klass->clear_modified_oops();
4425 
4426       // Tell the closure that this klass is the Klass to scavenge
4427       // and is the one to dirty if oops are left pointing into the young gen.
4428       _closure->set_scanned_klass(klass);
4429 
4430       klass->oops_do(_closure);
4431 
4432       _closure->set_scanned_klass(NULL);
4433     }
4434     _count++;
4435   }
4436 };
4437 
4438 class G1ParTask : public AbstractGangTask {
4439 protected:
4440   G1CollectedHeap*       _g1h;
4441   RefToScanQueueSet      *_queues;
4442   G1RootProcessor*       _root_processor;
4443   ParallelTaskTerminator _terminator;
4444   uint _n_workers;
4445 
4446   Mutex _stats_lock;
4447   Mutex* stats_lock() { return &_stats_lock; }
4448 
4449 public:
4450   G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4451     : AbstractGangTask("G1 collection"),
4452       _g1h(g1h),
4453       _queues(task_queues),
4454       _root_processor(root_processor),
4455       _terminator(n_workers, _queues),
4456       _n_workers(n_workers),
4457       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4458   {}
4459 
4460   RefToScanQueueSet* queues() { return _queues; }
4461 
4462   RefToScanQueue *work_queue(int i) {
4463     return queues()->queue(i);
4464   }
4465 
4466   ParallelTaskTerminator* terminator() { return &_terminator; }
4467 
4468   // Helps out with CLD processing.
4469   //
4470   // During InitialMark we need to:
4471   // 1) Scavenge all CLDs for the young GC.
4472   // 2) Mark all objects directly reachable from strong CLDs.
4473   template <G1Mark do_mark_object>
4474   class G1CLDClosure : public CLDClosure {
4475     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4476     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4477     G1KlassScanClosure                                _klass_in_cld_closure;
4478     bool                                              _claim;
4479 
4480    public:
4481     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4482                  bool only_young, bool claim)
4483         : _oop_closure(oop_closure),
4484           _oop_in_klass_closure(oop_closure->g1(),
4485                                 oop_closure->pss(),
4486                                 oop_closure->rp()),
4487           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4488           _claim(claim) {
4489 
4490     }
4491 
4492     void do_cld(ClassLoaderData* cld) {
4493       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4494     }
4495   };
4496 
4497   void work(uint worker_id) {
4498     if (worker_id >= _n_workers) return;  // no work needed this round
4499 
4500     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4501 
4502     {
4503       ResourceMark rm;
4504       HandleMark   hm;
4505 
4506       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4507 
4508       G1ParScanThreadState            pss(_g1h, worker_id, rp);
4509 
4510       bool only_young = _g1h->collector_state()->gcs_are_young();
4511 
4512       // Non-IM young GC.
4513       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
4514       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4515                                                                                only_young, // Only process dirty klasses.
4516                                                                                false);     // No need to claim CLDs.
4517       // IM young GC.
4518       //    Strong roots closures.
4519       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
4520       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4521                                                                                false, // Process all klasses.
4522                                                                                true); // Need to claim CLDs.
4523       //    Weak roots closures.
4524       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4525       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4526                                                                                     false, // Process all klasses.
4527                                                                                     true); // Need to claim CLDs.
4528 
4529       OopClosure* strong_root_cl;
4530       OopClosure* weak_root_cl;
4531       CLDClosure* strong_cld_cl;
4532       CLDClosure* weak_cld_cl;
4533 
4534       bool trace_metadata = false;
4535 
4536       if (_g1h->collector_state()->during_initial_mark_pause()) {
4537         // We also need to mark copied objects.
4538         strong_root_cl = &scan_mark_root_cl;
4539         strong_cld_cl  = &scan_mark_cld_cl;
4540         if (ClassUnloadingWithConcurrentMark) {
4541           weak_root_cl = &scan_mark_weak_root_cl;
4542           weak_cld_cl  = &scan_mark_weak_cld_cl;
4543           trace_metadata = true;
4544         } else {
4545           weak_root_cl = &scan_mark_root_cl;
4546           weak_cld_cl  = &scan_mark_cld_cl;
4547         }
4548       } else {
4549         strong_root_cl = &scan_only_root_cl;
4550         weak_root_cl   = &scan_only_root_cl;
4551         strong_cld_cl  = &scan_only_cld_cl;
4552         weak_cld_cl    = &scan_only_cld_cl;
4553       }
4554 
4555       pss.start_strong_roots();
4556 
4557       _root_processor->evacuate_roots(strong_root_cl,
4558                                       weak_root_cl,
4559                                       strong_cld_cl,
4560                                       weak_cld_cl,
4561                                       trace_metadata,
4562                                       worker_id);
4563 
4564       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4565       _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4566                                             weak_root_cl,
4567                                             worker_id);
4568       pss.end_strong_roots();
4569 
4570       {
4571         double start = os::elapsedTime();
4572         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4573         evac.do_void();
4574         double elapsed_sec = os::elapsedTime() - start;
4575         double term_sec = pss.term_time();
4576         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4577         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4578         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4579       }
4580       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4581       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4582 
4583       if (PrintTerminationStats) {
4584         MutexLocker x(stats_lock());
4585         pss.print_termination_stats(worker_id);
4586       }
4587 
4588       assert(pss.queue_is_empty(), "should be empty");
4589 
4590       // Close the inner scope so that the ResourceMark and HandleMark
4591       // destructors are executed here and are included as part of the
4592       // "GC Worker Time".
4593     }
4594     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4595   }
4596 };
4597 
4598 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4599 private:
4600   BoolObjectClosure* _is_alive;
4601   int _initial_string_table_size;
4602   int _initial_symbol_table_size;
4603 
4604   bool  _process_strings;
4605   int _strings_processed;
4606   int _strings_removed;
4607 
4608   bool  _process_symbols;
4609   int _symbols_processed;
4610   int _symbols_removed;
4611 
4612 public:
4613   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4614     AbstractGangTask("String/Symbol Unlinking"),
4615     _is_alive(is_alive),
4616     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4617     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4618 
4619     _initial_string_table_size = StringTable::the_table()->table_size();
4620     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4621     if (process_strings) {
4622       StringTable::clear_parallel_claimed_index();
4623     }
4624     if (process_symbols) {
4625       SymbolTable::clear_parallel_claimed_index();
4626     }
4627   }
4628 
4629   ~G1StringSymbolTableUnlinkTask() {
4630     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4631               err_msg("claim value %d after unlink less than initial string table size %d",
4632                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4633     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4634               err_msg("claim value %d after unlink less than initial symbol table size %d",
4635                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4636 
4637     if (G1TraceStringSymbolTableScrubbing) {
4638       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4639                              "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4640                              "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4641                              strings_processed(), strings_removed(),
4642                              symbols_processed(), symbols_removed());
4643     }
4644   }
4645 
4646   void work(uint worker_id) {
4647     int strings_processed = 0;
4648     int strings_removed = 0;
4649     int symbols_processed = 0;
4650     int symbols_removed = 0;
4651     if (_process_strings) {
4652       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4653       Atomic::add(strings_processed, &_strings_processed);
4654       Atomic::add(strings_removed, &_strings_removed);
4655     }
4656     if (_process_symbols) {
4657       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4658       Atomic::add(symbols_processed, &_symbols_processed);
4659       Atomic::add(symbols_removed, &_symbols_removed);
4660     }
4661   }
4662 
4663   size_t strings_processed() const { return (size_t)_strings_processed; }
4664   size_t strings_removed()   const { return (size_t)_strings_removed; }
4665 
4666   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4667   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4668 };
4669 
4670 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4671 private:
4672   static Monitor* _lock;
4673 
4674   BoolObjectClosure* const _is_alive;
4675   const bool               _unloading_occurred;
4676   const uint               _num_workers;
4677 
4678   // Variables used to claim nmethods.
4679   nmethod* _first_nmethod;
4680   volatile nmethod* _claimed_nmethod;
4681 
4682   // The list of nmethods that need to be processed by the second pass.
4683   volatile nmethod* _postponed_list;
4684   volatile uint     _num_entered_barrier;
4685 
4686  public:
4687   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4688       _is_alive(is_alive),
4689       _unloading_occurred(unloading_occurred),
4690       _num_workers(num_workers),
4691       _first_nmethod(NULL),
4692       _claimed_nmethod(NULL),
4693       _postponed_list(NULL),
4694       _num_entered_barrier(0)
4695   {
4696     nmethod::increase_unloading_clock();
4697     // Get first alive nmethod
4698     NMethodIterator iter = NMethodIterator();
4699     if(iter.next_alive()) {
4700       _first_nmethod = iter.method();
4701     }
4702     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4703   }
4704 
4705   ~G1CodeCacheUnloadingTask() {
4706     CodeCache::verify_clean_inline_caches();
4707 
4708     CodeCache::set_needs_cache_clean(false);
4709     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4710 
4711     CodeCache::verify_icholder_relocations();
4712   }
4713 
4714  private:
4715   void add_to_postponed_list(nmethod* nm) {
4716       nmethod* old;
4717       do {
4718         old = (nmethod*)_postponed_list;
4719         nm->set_unloading_next(old);
4720       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4721   }
4722 
4723   void clean_nmethod(nmethod* nm) {
4724     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4725 
4726     if (postponed) {
4727       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4728       add_to_postponed_list(nm);
4729     }
4730 
4731     // Mark that this thread has been cleaned/unloaded.
4732     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4733     nm->set_unloading_clock(nmethod::global_unloading_clock());
4734   }
4735 
4736   void clean_nmethod_postponed(nmethod* nm) {
4737     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4738   }
4739 
4740   static const int MaxClaimNmethods = 16;
4741 
4742   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4743     nmethod* first;
4744     NMethodIterator last;
4745 
4746     do {
4747       *num_claimed_nmethods = 0;
4748 
4749       first = (nmethod*)_claimed_nmethod;
4750       last = NMethodIterator(first);
4751 
4752       if (first != NULL) {
4753 
4754         for (int i = 0; i < MaxClaimNmethods; i++) {
4755           if (!last.next_alive()) {
4756             break;
4757           }
4758           claimed_nmethods[i] = last.method();
4759           (*num_claimed_nmethods)++;
4760         }
4761       }
4762 
4763     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4764   }
4765 
4766   nmethod* claim_postponed_nmethod() {
4767     nmethod* claim;
4768     nmethod* next;
4769 
4770     do {
4771       claim = (nmethod*)_postponed_list;
4772       if (claim == NULL) {
4773         return NULL;
4774       }
4775 
4776       next = claim->unloading_next();
4777 
4778     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4779 
4780     return claim;
4781   }
4782 
4783  public:
4784   // Mark that we're done with the first pass of nmethod cleaning.
4785   void barrier_mark(uint worker_id) {
4786     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4787     _num_entered_barrier++;
4788     if (_num_entered_barrier == _num_workers) {
4789       ml.notify_all();
4790     }
4791   }
4792 
4793   // See if we have to wait for the other workers to
4794   // finish their first-pass nmethod cleaning work.
4795   void barrier_wait(uint worker_id) {
4796     if (_num_entered_barrier < _num_workers) {
4797       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4798       while (_num_entered_barrier < _num_workers) {
4799           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4800       }
4801     }
4802   }
4803 
4804   // Cleaning and unloading of nmethods. Some work has to be postponed
4805   // to the second pass, when we know which nmethods survive.
4806   void work_first_pass(uint worker_id) {
4807     // The first nmethods is claimed by the first worker.
4808     if (worker_id == 0 && _first_nmethod != NULL) {
4809       clean_nmethod(_first_nmethod);
4810       _first_nmethod = NULL;
4811     }
4812 
4813     int num_claimed_nmethods;
4814     nmethod* claimed_nmethods[MaxClaimNmethods];
4815 
4816     while (true) {
4817       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4818 
4819       if (num_claimed_nmethods == 0) {
4820         break;
4821       }
4822 
4823       for (int i = 0; i < num_claimed_nmethods; i++) {
4824         clean_nmethod(claimed_nmethods[i]);
4825       }
4826     }
4827   }
4828 
4829   void work_second_pass(uint worker_id) {
4830     nmethod* nm;
4831     // Take care of postponed nmethods.
4832     while ((nm = claim_postponed_nmethod()) != NULL) {
4833       clean_nmethod_postponed(nm);
4834     }
4835   }
4836 };
4837 
4838 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4839 
4840 class G1KlassCleaningTask : public StackObj {
4841   BoolObjectClosure*                      _is_alive;
4842   volatile jint                           _clean_klass_tree_claimed;
4843   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4844 
4845  public:
4846   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4847       _is_alive(is_alive),
4848       _clean_klass_tree_claimed(0),
4849       _klass_iterator() {
4850   }
4851 
4852  private:
4853   bool claim_clean_klass_tree_task() {
4854     if (_clean_klass_tree_claimed) {
4855       return false;
4856     }
4857 
4858     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4859   }
4860 
4861   InstanceKlass* claim_next_klass() {
4862     Klass* klass;
4863     do {
4864       klass =_klass_iterator.next_klass();
4865     } while (klass != NULL && !klass->oop_is_instance());
4866 
4867     return (InstanceKlass*)klass;
4868   }
4869 
4870 public:
4871 
4872   void clean_klass(InstanceKlass* ik) {
4873     ik->clean_implementors_list(_is_alive);
4874     ik->clean_method_data(_is_alive);
4875 
4876     // G1 specific cleanup work that has
4877     // been moved here to be done in parallel.
4878     ik->clean_dependent_nmethods();
4879   }
4880 
4881   void work() {
4882     ResourceMark rm;
4883 
4884     // One worker will clean the subklass/sibling klass tree.
4885     if (claim_clean_klass_tree_task()) {
4886       Klass::clean_subklass_tree(_is_alive);
4887     }
4888 
4889     // All workers will help cleaning the classes,
4890     InstanceKlass* klass;
4891     while ((klass = claim_next_klass()) != NULL) {
4892       clean_klass(klass);
4893     }
4894   }
4895 };
4896 
4897 // To minimize the remark pause times, the tasks below are done in parallel.
4898 class G1ParallelCleaningTask : public AbstractGangTask {
4899 private:
4900   G1StringSymbolTableUnlinkTask _string_symbol_task;
4901   G1CodeCacheUnloadingTask      _code_cache_task;
4902   G1KlassCleaningTask           _klass_cleaning_task;
4903 
4904 public:
4905   // The constructor is run in the VMThread.
4906   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4907       AbstractGangTask("Parallel Cleaning"),
4908       _string_symbol_task(is_alive, process_strings, process_symbols),
4909       _code_cache_task(num_workers, is_alive, unloading_occurred),
4910       _klass_cleaning_task(is_alive) {
4911   }
4912 
4913   // The parallel work done by all worker threads.
4914   void work(uint worker_id) {
4915     // Do first pass of code cache cleaning.
4916     _code_cache_task.work_first_pass(worker_id);
4917 
4918     // Let the threads mark that the first pass is done.
4919     _code_cache_task.barrier_mark(worker_id);
4920 
4921     // Clean the Strings and Symbols.
4922     _string_symbol_task.work(worker_id);
4923 
4924     // Wait for all workers to finish the first code cache cleaning pass.
4925     _code_cache_task.barrier_wait(worker_id);
4926 
4927     // Do the second code cache cleaning work, which realize on
4928     // the liveness information gathered during the first pass.
4929     _code_cache_task.work_second_pass(worker_id);
4930 
4931     // Clean all klasses that were not unloaded.
4932     _klass_cleaning_task.work();
4933   }
4934 };
4935 
4936 
4937 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4938                                         bool process_strings,
4939                                         bool process_symbols,
4940                                         bool class_unloading_occurred) {
4941   uint n_workers = workers()->active_workers();
4942 
4943   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4944                                         n_workers, class_unloading_occurred);
4945   workers()->run_task(&g1_unlink_task);
4946 }
4947 
4948 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4949                                                      bool process_strings, bool process_symbols) {
4950   {
4951     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4952     workers()->run_task(&g1_unlink_task);
4953   }
4954 
4955   if (G1StringDedup::is_enabled()) {
4956     G1StringDedup::unlink(is_alive);
4957   }
4958 }
4959 
4960 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4961  private:
4962   DirtyCardQueueSet* _queue;
4963  public:
4964   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4965 
4966   virtual void work(uint worker_id) {
4967     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4968     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4969 
4970     RedirtyLoggedCardTableEntryClosure cl;
4971     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4972 
4973     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4974   }
4975 };
4976 
4977 void G1CollectedHeap::redirty_logged_cards() {
4978   double redirty_logged_cards_start = os::elapsedTime();
4979 
4980   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4981   dirty_card_queue_set().reset_for_par_iteration();
4982   workers()->run_task(&redirty_task);
4983 
4984   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4985   dcq.merge_bufferlists(&dirty_card_queue_set());
4986   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4987 
4988   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4989 }
4990 
4991 // Weak Reference Processing support
4992 
4993 // An always "is_alive" closure that is used to preserve referents.
4994 // If the object is non-null then it's alive.  Used in the preservation
4995 // of referent objects that are pointed to by reference objects
4996 // discovered by the CM ref processor.
4997 class G1AlwaysAliveClosure: public BoolObjectClosure {
4998   G1CollectedHeap* _g1;
4999 public:
5000   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5001   bool do_object_b(oop p) {
5002     if (p != NULL) {
5003       return true;
5004     }
5005     return false;
5006   }
5007 };
5008 
5009 bool G1STWIsAliveClosure::do_object_b(oop p) {
5010   // An object is reachable if it is outside the collection set,
5011   // or is inside and copied.
5012   return !_g1->obj_in_cs(p) || p->is_forwarded();
5013 }
5014 
5015 // Non Copying Keep Alive closure
5016 class G1KeepAliveClosure: public OopClosure {
5017   G1CollectedHeap* _g1;
5018 public:
5019   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5020   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5021   void do_oop(oop* p) {
5022     oop obj = *p;
5023     assert(obj != NULL, "the caller should have filtered out NULL values");
5024 
5025     const InCSetState cset_state = _g1->in_cset_state(obj);
5026     if (!cset_state.is_in_cset_or_humongous()) {
5027       return;
5028     }
5029     if (cset_state.is_in_cset()) {
5030       assert( obj->is_forwarded(), "invariant" );
5031       *p = obj->forwardee();
5032     } else {
5033       assert(!obj->is_forwarded(), "invariant" );
5034       assert(cset_state.is_humongous(),
5035              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5036       _g1->set_humongous_is_live(obj);
5037     }
5038   }
5039 };
5040 
5041 // Copying Keep Alive closure - can be called from both
5042 // serial and parallel code as long as different worker
5043 // threads utilize different G1ParScanThreadState instances
5044 // and different queues.
5045 
5046 class G1CopyingKeepAliveClosure: public OopClosure {
5047   G1CollectedHeap*         _g1h;
5048   OopClosure*              _copy_non_heap_obj_cl;
5049   G1ParScanThreadState*    _par_scan_state;
5050 
5051 public:
5052   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5053                             OopClosure* non_heap_obj_cl,
5054                             G1ParScanThreadState* pss):
5055     _g1h(g1h),
5056     _copy_non_heap_obj_cl(non_heap_obj_cl),
5057     _par_scan_state(pss)
5058   {}
5059 
5060   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5061   virtual void do_oop(      oop* p) { do_oop_work(p); }
5062 
5063   template <class T> void do_oop_work(T* p) {
5064     oop obj = oopDesc::load_decode_heap_oop(p);
5065 
5066     if (_g1h->is_in_cset_or_humongous(obj)) {
5067       // If the referent object has been forwarded (either copied
5068       // to a new location or to itself in the event of an
5069       // evacuation failure) then we need to update the reference
5070       // field and, if both reference and referent are in the G1
5071       // heap, update the RSet for the referent.
5072       //
5073       // If the referent has not been forwarded then we have to keep
5074       // it alive by policy. Therefore we have copy the referent.
5075       //
5076       // If the reference field is in the G1 heap then we can push
5077       // on the PSS queue. When the queue is drained (after each
5078       // phase of reference processing) the object and it's followers
5079       // will be copied, the reference field set to point to the
5080       // new location, and the RSet updated. Otherwise we need to
5081       // use the the non-heap or metadata closures directly to copy
5082       // the referent object and update the pointer, while avoiding
5083       // updating the RSet.
5084 
5085       if (_g1h->is_in_g1_reserved(p)) {
5086         _par_scan_state->push_on_queue(p);
5087       } else {
5088         assert(!Metaspace::contains((const void*)p),
5089                err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5090         _copy_non_heap_obj_cl->do_oop(p);
5091       }
5092     }
5093   }
5094 };
5095 
5096 // Serial drain queue closure. Called as the 'complete_gc'
5097 // closure for each discovered list in some of the
5098 // reference processing phases.
5099 
5100 class G1STWDrainQueueClosure: public VoidClosure {
5101 protected:
5102   G1CollectedHeap* _g1h;
5103   G1ParScanThreadState* _par_scan_state;
5104 
5105   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5106 
5107 public:
5108   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5109     _g1h(g1h),
5110     _par_scan_state(pss)
5111   { }
5112 
5113   void do_void() {
5114     G1ParScanThreadState* const pss = par_scan_state();
5115     pss->trim_queue();
5116   }
5117 };
5118 
5119 // Parallel Reference Processing closures
5120 
5121 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5122 // processing during G1 evacuation pauses.
5123 
5124 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5125 private:
5126   G1CollectedHeap*   _g1h;
5127   RefToScanQueueSet* _queues;
5128   FlexibleWorkGang*  _workers;
5129   uint               _active_workers;
5130 
5131 public:
5132   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5133                            FlexibleWorkGang* workers,
5134                            RefToScanQueueSet *task_queues,
5135                            uint n_workers) :
5136     _g1h(g1h),
5137     _queues(task_queues),
5138     _workers(workers),
5139     _active_workers(n_workers)
5140   {
5141     assert(n_workers > 0, "shouldn't call this otherwise");
5142   }
5143 
5144   // Executes the given task using concurrent marking worker threads.
5145   virtual void execute(ProcessTask& task);
5146   virtual void execute(EnqueueTask& task);
5147 };
5148 
5149 // Gang task for possibly parallel reference processing
5150 
5151 class G1STWRefProcTaskProxy: public AbstractGangTask {
5152   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5153   ProcessTask&     _proc_task;
5154   G1CollectedHeap* _g1h;
5155   RefToScanQueueSet *_task_queues;
5156   ParallelTaskTerminator* _terminator;
5157 
5158 public:
5159   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5160                      G1CollectedHeap* g1h,
5161                      RefToScanQueueSet *task_queues,
5162                      ParallelTaskTerminator* terminator) :
5163     AbstractGangTask("Process reference objects in parallel"),
5164     _proc_task(proc_task),
5165     _g1h(g1h),
5166     _task_queues(task_queues),
5167     _terminator(terminator)
5168   {}
5169 
5170   virtual void work(uint worker_id) {
5171     // The reference processing task executed by a single worker.
5172     ResourceMark rm;
5173     HandleMark   hm;
5174 
5175     G1STWIsAliveClosure is_alive(_g1h);
5176 
5177     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5178 
5179     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5180 
5181     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5182 
5183     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5184 
5185     if (_g1h->collector_state()->during_initial_mark_pause()) {
5186       // We also need to mark copied objects.
5187       copy_non_heap_cl = &copy_mark_non_heap_cl;
5188     }
5189 
5190     // Keep alive closure.
5191     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5192 
5193     // Complete GC closure
5194     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5195 
5196     // Call the reference processing task's work routine.
5197     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5198 
5199     // Note we cannot assert that the refs array is empty here as not all
5200     // of the processing tasks (specifically phase2 - pp2_work) execute
5201     // the complete_gc closure (which ordinarily would drain the queue) so
5202     // the queue may not be empty.
5203   }
5204 };
5205 
5206 // Driver routine for parallel reference processing.
5207 // Creates an instance of the ref processing gang
5208 // task and has the worker threads execute it.
5209 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5210   assert(_workers != NULL, "Need parallel worker threads.");
5211 
5212   ParallelTaskTerminator terminator(_active_workers, _queues);
5213   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5214 
5215   _workers->run_task(&proc_task_proxy);
5216 }
5217 
5218 // Gang task for parallel reference enqueueing.
5219 
5220 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5221   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5222   EnqueueTask& _enq_task;
5223 
5224 public:
5225   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5226     AbstractGangTask("Enqueue reference objects in parallel"),
5227     _enq_task(enq_task)
5228   { }
5229 
5230   virtual void work(uint worker_id) {
5231     _enq_task.work(worker_id);
5232   }
5233 };
5234 
5235 // Driver routine for parallel reference enqueueing.
5236 // Creates an instance of the ref enqueueing gang
5237 // task and has the worker threads execute it.
5238 
5239 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5240   assert(_workers != NULL, "Need parallel worker threads.");
5241 
5242   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5243 
5244   _workers->run_task(&enq_task_proxy);
5245 }
5246 
5247 // End of weak reference support closures
5248 
5249 // Abstract task used to preserve (i.e. copy) any referent objects
5250 // that are in the collection set and are pointed to by reference
5251 // objects discovered by the CM ref processor.
5252 
5253 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5254 protected:
5255   G1CollectedHeap* _g1h;
5256   RefToScanQueueSet      *_queues;
5257   ParallelTaskTerminator _terminator;
5258   uint _n_workers;
5259 
5260 public:
5261   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5262     AbstractGangTask("ParPreserveCMReferents"),
5263     _g1h(g1h),
5264     _queues(task_queues),
5265     _terminator(workers, _queues),
5266     _n_workers(workers)
5267   { }
5268 
5269   void work(uint worker_id) {
5270     ResourceMark rm;
5271     HandleMark   hm;
5272 
5273     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5274     assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5275 
5276     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5277 
5278     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5279 
5280     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5281 
5282     if (_g1h->collector_state()->during_initial_mark_pause()) {
5283       // We also need to mark copied objects.
5284       copy_non_heap_cl = &copy_mark_non_heap_cl;
5285     }
5286 
5287     // Is alive closure
5288     G1AlwaysAliveClosure always_alive(_g1h);
5289 
5290     // Copying keep alive closure. Applied to referent objects that need
5291     // to be copied.
5292     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5293 
5294     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5295 
5296     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5297     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5298 
5299     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5300     // So this must be true - but assert just in case someone decides to
5301     // change the worker ids.
5302     assert(worker_id < limit, "sanity");
5303     assert(!rp->discovery_is_atomic(), "check this code");
5304 
5305     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5306     for (uint idx = worker_id; idx < limit; idx += stride) {
5307       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5308 
5309       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5310       while (iter.has_next()) {
5311         // Since discovery is not atomic for the CM ref processor, we
5312         // can see some null referent objects.
5313         iter.load_ptrs(DEBUG_ONLY(true));
5314         oop ref = iter.obj();
5315 
5316         // This will filter nulls.
5317         if (iter.is_referent_alive()) {
5318           iter.make_referent_alive();
5319         }
5320         iter.move_to_next();
5321       }
5322     }
5323 
5324     // Drain the queue - which may cause stealing
5325     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5326     drain_queue.do_void();
5327     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5328     assert(pss.queue_is_empty(), "should be");
5329   }
5330 };
5331 
5332 // Weak Reference processing during an evacuation pause (part 1).
5333 void G1CollectedHeap::process_discovered_references() {
5334   double ref_proc_start = os::elapsedTime();
5335 
5336   ReferenceProcessor* rp = _ref_processor_stw;
5337   assert(rp->discovery_enabled(), "should have been enabled");
5338 
5339   // Any reference objects, in the collection set, that were 'discovered'
5340   // by the CM ref processor should have already been copied (either by
5341   // applying the external root copy closure to the discovered lists, or
5342   // by following an RSet entry).
5343   //
5344   // But some of the referents, that are in the collection set, that these
5345   // reference objects point to may not have been copied: the STW ref
5346   // processor would have seen that the reference object had already
5347   // been 'discovered' and would have skipped discovering the reference,
5348   // but would not have treated the reference object as a regular oop.
5349   // As a result the copy closure would not have been applied to the
5350   // referent object.
5351   //
5352   // We need to explicitly copy these referent objects - the references
5353   // will be processed at the end of remarking.
5354   //
5355   // We also need to do this copying before we process the reference
5356   // objects discovered by the STW ref processor in case one of these
5357   // referents points to another object which is also referenced by an
5358   // object discovered by the STW ref processor.
5359 
5360   uint no_of_gc_workers = workers()->active_workers();
5361 
5362   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5363                                                  no_of_gc_workers,
5364                                                  _task_queues);
5365 
5366   workers()->run_task(&keep_cm_referents);
5367 
5368   // Closure to test whether a referent is alive.
5369   G1STWIsAliveClosure is_alive(this);
5370 
5371   // Even when parallel reference processing is enabled, the processing
5372   // of JNI refs is serial and performed serially by the current thread
5373   // rather than by a worker. The following PSS will be used for processing
5374   // JNI refs.
5375 
5376   // Use only a single queue for this PSS.
5377   G1ParScanThreadState            pss(this, 0, NULL);
5378   assert(pss.queue_is_empty(), "pre-condition");
5379 
5380   // We do not embed a reference processor in the copying/scanning
5381   // closures while we're actually processing the discovered
5382   // reference objects.
5383 
5384   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5385 
5386   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5387 
5388   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5389 
5390   if (collector_state()->during_initial_mark_pause()) {
5391     // We also need to mark copied objects.
5392     copy_non_heap_cl = &copy_mark_non_heap_cl;
5393   }
5394 
5395   // Keep alive closure.
5396   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5397 
5398   // Serial Complete GC closure
5399   G1STWDrainQueueClosure drain_queue(this, &pss);
5400 
5401   // Setup the soft refs policy...
5402   rp->setup_policy(false);
5403 
5404   ReferenceProcessorStats stats;
5405   if (!rp->processing_is_mt()) {
5406     // Serial reference processing...
5407     stats = rp->process_discovered_references(&is_alive,
5408                                               &keep_alive,
5409                                               &drain_queue,
5410                                               NULL,
5411                                               _gc_timer_stw,
5412                                               _gc_tracer_stw->gc_id());
5413   } else {
5414     // Parallel reference processing
5415     assert(rp->num_q() == no_of_gc_workers, "sanity");
5416     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5417 
5418     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5419     stats = rp->process_discovered_references(&is_alive,
5420                                               &keep_alive,
5421                                               &drain_queue,
5422                                               &par_task_executor,
5423                                               _gc_timer_stw,
5424                                               _gc_tracer_stw->gc_id());
5425   }
5426 
5427   _gc_tracer_stw->report_gc_reference_stats(stats);
5428 
5429   // We have completed copying any necessary live referent objects.
5430   assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5431 
5432   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5433   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5434 }
5435 
5436 // Weak Reference processing during an evacuation pause (part 2).
5437 void G1CollectedHeap::enqueue_discovered_references() {
5438   double ref_enq_start = os::elapsedTime();
5439 
5440   ReferenceProcessor* rp = _ref_processor_stw;
5441   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5442 
5443   // Now enqueue any remaining on the discovered lists on to
5444   // the pending list.
5445   if (!rp->processing_is_mt()) {
5446     // Serial reference processing...
5447     rp->enqueue_discovered_references();
5448   } else {
5449     // Parallel reference enqueueing
5450 
5451     uint n_workers = workers()->active_workers();
5452 
5453     assert(rp->num_q() == n_workers, "sanity");
5454     assert(n_workers <= rp->max_num_q(), "sanity");
5455 
5456     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5457     rp->enqueue_discovered_references(&par_task_executor);
5458   }
5459 
5460   rp->verify_no_references_recorded();
5461   assert(!rp->discovery_enabled(), "should have been disabled");
5462 
5463   // FIXME
5464   // CM's reference processing also cleans up the string and symbol tables.
5465   // Should we do that here also? We could, but it is a serial operation
5466   // and could significantly increase the pause time.
5467 
5468   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5469   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5470 }
5471 
5472 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5473   _expand_heap_after_alloc_failure = true;
5474   _evacuation_failed = false;
5475 
5476   // Should G1EvacuationFailureALot be in effect for this GC?
5477   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5478 
5479   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5480 
5481   // Disable the hot card cache.
5482   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5483   hot_card_cache->reset_hot_cache_claimed_index();
5484   hot_card_cache->set_use_cache(false);
5485 
5486   const uint n_workers = workers()->active_workers();
5487 
5488   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5489   double start_par_time_sec = os::elapsedTime();
5490   double end_par_time_sec;
5491 
5492   {
5493     G1RootProcessor root_processor(this, n_workers);
5494     G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5495     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5496     if (collector_state()->during_initial_mark_pause()) {
5497       ClassLoaderDataGraph::clear_claimed_marks();
5498     }
5499 
5500     // The individual threads will set their evac-failure closures.
5501     if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5502 
5503     workers()->run_task(&g1_par_task);
5504     end_par_time_sec = os::elapsedTime();
5505 
5506     // Closing the inner scope will execute the destructor
5507     // for the G1RootProcessor object. We record the current
5508     // elapsed time before closing the scope so that time
5509     // taken for the destructor is NOT included in the
5510     // reported parallel time.
5511   }
5512 
5513   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5514 
5515   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5516   phase_times->record_par_time(par_time_ms);
5517 
5518   double code_root_fixup_time_ms =
5519         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5520   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5521 
5522   // Process any discovered reference objects - we have
5523   // to do this _before_ we retire the GC alloc regions
5524   // as we may have to copy some 'reachable' referent
5525   // objects (and their reachable sub-graphs) that were
5526   // not copied during the pause.
5527   process_discovered_references();
5528 
5529   if (G1StringDedup::is_enabled()) {
5530     double fixup_start = os::elapsedTime();
5531 
5532     G1STWIsAliveClosure is_alive(this);
5533     G1KeepAliveClosure keep_alive(this);
5534     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5535 
5536     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5537     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5538   }
5539 
5540   _allocator->release_gc_alloc_regions(evacuation_info);
5541   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5542 
5543   // Reset and re-enable the hot card cache.
5544   // Note the counts for the cards in the regions in the
5545   // collection set are reset when the collection set is freed.
5546   hot_card_cache->reset_hot_cache();
5547   hot_card_cache->set_use_cache(true);
5548 
5549   purge_code_root_memory();
5550 
5551   if (evacuation_failed()) {
5552     remove_self_forwarding_pointers();
5553 
5554     // Reset the G1EvacuationFailureALot counters and flags
5555     // Note: the values are reset only when an actual
5556     // evacuation failure occurs.
5557     NOT_PRODUCT(reset_evacuation_should_fail();)
5558   }
5559 
5560   // Enqueue any remaining references remaining on the STW
5561   // reference processor's discovered lists. We need to do
5562   // this after the card table is cleaned (and verified) as
5563   // the act of enqueueing entries on to the pending list
5564   // will log these updates (and dirty their associated
5565   // cards). We need these updates logged to update any
5566   // RSets.
5567   enqueue_discovered_references();
5568 
5569   redirty_logged_cards();
5570   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5571 }
5572 
5573 void G1CollectedHeap::free_region(HeapRegion* hr,
5574                                   FreeRegionList* free_list,
5575                                   bool par,
5576                                   bool locked) {
5577   assert(!hr->is_free(), "the region should not be free");
5578   assert(!hr->is_empty(), "the region should not be empty");
5579   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5580   assert(free_list != NULL, "pre-condition");
5581 
5582   if (G1VerifyBitmaps) {
5583     MemRegion mr(hr->bottom(), hr->end());
5584     concurrent_mark()->clearRangePrevBitmap(mr);
5585   }
5586 
5587   // Clear the card counts for this region.
5588   // Note: we only need to do this if the region is not young
5589   // (since we don't refine cards in young regions).
5590   if (!hr->is_young()) {
5591     _cg1r->hot_card_cache()->reset_card_counts(hr);
5592   }
5593   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5594   free_list->add_ordered(hr);
5595 }
5596 
5597 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5598                                      FreeRegionList* free_list,
5599                                      bool par) {
5600   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5601   assert(free_list != NULL, "pre-condition");
5602 
5603   size_t hr_capacity = hr->capacity();
5604   // We need to read this before we make the region non-humongous,
5605   // otherwise the information will be gone.
5606   uint last_index = hr->last_hc_index();
5607   hr->clear_humongous();
5608   free_region(hr, free_list, par);
5609 
5610   uint i = hr->hrm_index() + 1;
5611   while (i < last_index) {
5612     HeapRegion* curr_hr = region_at(i);
5613     assert(curr_hr->is_continues_humongous(), "invariant");
5614     curr_hr->clear_humongous();
5615     free_region(curr_hr, free_list, par);
5616     i += 1;
5617   }
5618 }
5619 
5620 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5621                                        const HeapRegionSetCount& humongous_regions_removed) {
5622   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5623     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5624     _old_set.bulk_remove(old_regions_removed);
5625     _humongous_set.bulk_remove(humongous_regions_removed);
5626   }
5627 
5628 }
5629 
5630 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5631   assert(list != NULL, "list can't be null");
5632   if (!list->is_empty()) {
5633     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5634     _hrm.insert_list_into_free_list(list);
5635   }
5636 }
5637 
5638 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5639   decrease_used(bytes);
5640 }
5641 
5642 class G1ParCleanupCTTask : public AbstractGangTask {
5643   G1SATBCardTableModRefBS* _ct_bs;
5644   G1CollectedHeap* _g1h;
5645   HeapRegion* volatile _su_head;
5646 public:
5647   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5648                      G1CollectedHeap* g1h) :
5649     AbstractGangTask("G1 Par Cleanup CT Task"),
5650     _ct_bs(ct_bs), _g1h(g1h) { }
5651 
5652   void work(uint worker_id) {
5653     HeapRegion* r;
5654     while (r = _g1h->pop_dirty_cards_region()) {
5655       clear_cards(r);
5656     }
5657   }
5658 
5659   void clear_cards(HeapRegion* r) {
5660     // Cards of the survivors should have already been dirtied.
5661     if (!r->is_survivor()) {
5662       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5663     }
5664   }
5665 };
5666 
5667 #ifndef PRODUCT
5668 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5669   G1CollectedHeap* _g1h;
5670   G1SATBCardTableModRefBS* _ct_bs;
5671 public:
5672   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5673     : _g1h(g1h), _ct_bs(ct_bs) { }
5674   virtual bool doHeapRegion(HeapRegion* r) {
5675     if (r->is_survivor()) {
5676       _g1h->verify_dirty_region(r);
5677     } else {
5678       _g1h->verify_not_dirty_region(r);
5679     }
5680     return false;
5681   }
5682 };
5683 
5684 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5685   // All of the region should be clean.
5686   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5687   MemRegion mr(hr->bottom(), hr->end());
5688   ct_bs->verify_not_dirty_region(mr);
5689 }
5690 
5691 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5692   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5693   // dirty allocated blocks as they allocate them. The thread that
5694   // retires each region and replaces it with a new one will do a
5695   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5696   // not dirty that area (one less thing to have to do while holding
5697   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5698   // is dirty.
5699   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5700   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5701   if (hr->is_young()) {
5702     ct_bs->verify_g1_young_region(mr);
5703   } else {
5704     ct_bs->verify_dirty_region(mr);
5705   }
5706 }
5707 
5708 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5709   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5710   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5711     verify_dirty_region(hr);
5712   }
5713 }
5714 
5715 void G1CollectedHeap::verify_dirty_young_regions() {
5716   verify_dirty_young_list(_young_list->first_region());
5717 }
5718 
5719 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5720                                                HeapWord* tams, HeapWord* end) {
5721   guarantee(tams <= end,
5722             err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5723   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5724   if (result < end) {
5725     gclog_or_tty->cr();
5726     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5727                            bitmap_name, p2i(result));
5728     gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5729                            bitmap_name, p2i(tams), p2i(end));
5730     return false;
5731   }
5732   return true;
5733 }
5734 
5735 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5736   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5737   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5738 
5739   HeapWord* bottom = hr->bottom();
5740   HeapWord* ptams  = hr->prev_top_at_mark_start();
5741   HeapWord* ntams  = hr->next_top_at_mark_start();
5742   HeapWord* end    = hr->end();
5743 
5744   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5745 
5746   bool res_n = true;
5747   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5748   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5749   // if we happen to be in that state.
5750   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5751     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5752   }
5753   if (!res_p || !res_n) {
5754     gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5755                            HR_FORMAT_PARAMS(hr));
5756     gclog_or_tty->print_cr("#### Caller: %s", caller);
5757     return false;
5758   }
5759   return true;
5760 }
5761 
5762 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5763   if (!G1VerifyBitmaps) return;
5764 
5765   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5766 }
5767 
5768 class G1VerifyBitmapClosure : public HeapRegionClosure {
5769 private:
5770   const char* _caller;
5771   G1CollectedHeap* _g1h;
5772   bool _failures;
5773 
5774 public:
5775   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5776     _caller(caller), _g1h(g1h), _failures(false) { }
5777 
5778   bool failures() { return _failures; }
5779 
5780   virtual bool doHeapRegion(HeapRegion* hr) {
5781     if (hr->is_continues_humongous()) return false;
5782 
5783     bool result = _g1h->verify_bitmaps(_caller, hr);
5784     if (!result) {
5785       _failures = true;
5786     }
5787     return false;
5788   }
5789 };
5790 
5791 void G1CollectedHeap::check_bitmaps(const char* caller) {
5792   if (!G1VerifyBitmaps) return;
5793 
5794   G1VerifyBitmapClosure cl(caller, this);
5795   heap_region_iterate(&cl);
5796   guarantee(!cl.failures(), "bitmap verification");
5797 }
5798 
5799 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5800  private:
5801   bool _failures;
5802  public:
5803   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5804 
5805   virtual bool doHeapRegion(HeapRegion* hr) {
5806     uint i = hr->hrm_index();
5807     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5808     if (hr->is_humongous()) {
5809       if (hr->in_collection_set()) {
5810         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5811         _failures = true;
5812         return true;
5813       }
5814       if (cset_state.is_in_cset()) {
5815         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5816         _failures = true;
5817         return true;
5818       }
5819       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5820         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5821         _failures = true;
5822         return true;
5823       }
5824     } else {
5825       if (cset_state.is_humongous()) {
5826         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5827         _failures = true;
5828         return true;
5829       }
5830       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5831         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5832                                hr->in_collection_set(), cset_state.value(), i);
5833         _failures = true;
5834         return true;
5835       }
5836       if (cset_state.is_in_cset()) {
5837         if (hr->is_young() != (cset_state.is_young())) {
5838           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5839                                  hr->is_young(), cset_state.value(), i);
5840           _failures = true;
5841           return true;
5842         }
5843         if (hr->is_old() != (cset_state.is_old())) {
5844           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5845                                  hr->is_old(), cset_state.value(), i);
5846           _failures = true;
5847           return true;
5848         }
5849       }
5850     }
5851     return false;
5852   }
5853 
5854   bool failures() const { return _failures; }
5855 };
5856 
5857 bool G1CollectedHeap::check_cset_fast_test() {
5858   G1CheckCSetFastTableClosure cl;
5859   _hrm.iterate(&cl);
5860   return !cl.failures();
5861 }
5862 #endif // PRODUCT
5863 
5864 void G1CollectedHeap::cleanUpCardTable() {
5865   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5866   double start = os::elapsedTime();
5867 
5868   {
5869     // Iterate over the dirty cards region list.
5870     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5871 
5872     workers()->run_task(&cleanup_task);
5873 #ifndef PRODUCT
5874     if (G1VerifyCTCleanup || VerifyAfterGC) {
5875       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5876       heap_region_iterate(&cleanup_verifier);
5877     }
5878 #endif
5879   }
5880 
5881   double elapsed = os::elapsedTime() - start;
5882   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5883 }
5884 
5885 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5886   size_t pre_used = 0;
5887   FreeRegionList local_free_list("Local List for CSet Freeing");
5888 
5889   double young_time_ms     = 0.0;
5890   double non_young_time_ms = 0.0;
5891 
5892   // Since the collection set is a superset of the the young list,
5893   // all we need to do to clear the young list is clear its
5894   // head and length, and unlink any young regions in the code below
5895   _young_list->clear();
5896 
5897   G1CollectorPolicy* policy = g1_policy();
5898 
5899   double start_sec = os::elapsedTime();
5900   bool non_young = true;
5901 
5902   HeapRegion* cur = cs_head;
5903   int age_bound = -1;
5904   size_t rs_lengths = 0;
5905 
5906   while (cur != NULL) {
5907     assert(!is_on_master_free_list(cur), "sanity");
5908     if (non_young) {
5909       if (cur->is_young()) {
5910         double end_sec = os::elapsedTime();
5911         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5912         non_young_time_ms += elapsed_ms;
5913 
5914         start_sec = os::elapsedTime();
5915         non_young = false;
5916       }
5917     } else {
5918       if (!cur->is_young()) {
5919         double end_sec = os::elapsedTime();
5920         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5921         young_time_ms += elapsed_ms;
5922 
5923         start_sec = os::elapsedTime();
5924         non_young = true;
5925       }
5926     }
5927 
5928     rs_lengths += cur->rem_set()->occupied_locked();
5929 
5930     HeapRegion* next = cur->next_in_collection_set();
5931     assert(cur->in_collection_set(), "bad CS");
5932     cur->set_next_in_collection_set(NULL);
5933     clear_in_cset(cur);
5934 
5935     if (cur->is_young()) {
5936       int index = cur->young_index_in_cset();
5937       assert(index != -1, "invariant");
5938       assert((uint) index < policy->young_cset_region_length(), "invariant");
5939       size_t words_survived = _surviving_young_words[index];
5940       cur->record_surv_words_in_group(words_survived);
5941 
5942       // At this point the we have 'popped' cur from the collection set
5943       // (linked via next_in_collection_set()) but it is still in the
5944       // young list (linked via next_young_region()). Clear the
5945       // _next_young_region field.
5946       cur->set_next_young_region(NULL);
5947     } else {
5948       int index = cur->young_index_in_cset();
5949       assert(index == -1, "invariant");
5950     }
5951 
5952     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5953             (!cur->is_young() && cur->young_index_in_cset() == -1),
5954             "invariant" );
5955 
5956     if (!cur->evacuation_failed()) {
5957       MemRegion used_mr = cur->used_region();
5958 
5959       // And the region is empty.
5960       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5961       pre_used += cur->used();
5962       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5963     } else {
5964       cur->uninstall_surv_rate_group();
5965       if (cur->is_young()) {
5966         cur->set_young_index_in_cset(-1);
5967       }
5968       cur->set_evacuation_failed(false);
5969       // The region is now considered to be old.
5970       cur->set_old();
5971       _old_set.add(cur);
5972       evacuation_info.increment_collectionset_used_after(cur->used());
5973     }
5974     cur = next;
5975   }
5976 
5977   evacuation_info.set_regions_freed(local_free_list.length());
5978   policy->record_max_rs_lengths(rs_lengths);
5979   policy->cset_regions_freed();
5980 
5981   double end_sec = os::elapsedTime();
5982   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5983 
5984   if (non_young) {
5985     non_young_time_ms += elapsed_ms;
5986   } else {
5987     young_time_ms += elapsed_ms;
5988   }
5989 
5990   prepend_to_freelist(&local_free_list);
5991   decrement_summary_bytes(pre_used);
5992   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5993   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5994 }
5995 
5996 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5997  private:
5998   FreeRegionList* _free_region_list;
5999   HeapRegionSet* _proxy_set;
6000   HeapRegionSetCount _humongous_regions_removed;
6001   size_t _freed_bytes;
6002  public:
6003 
6004   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6005     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6006   }
6007 
6008   virtual bool doHeapRegion(HeapRegion* r) {
6009     if (!r->is_starts_humongous()) {
6010       return false;
6011     }
6012 
6013     G1CollectedHeap* g1h = G1CollectedHeap::heap();
6014 
6015     oop obj = (oop)r->bottom();
6016     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6017 
6018     // The following checks whether the humongous object is live are sufficient.
6019     // The main additional check (in addition to having a reference from the roots
6020     // or the young gen) is whether the humongous object has a remembered set entry.
6021     //
6022     // A humongous object cannot be live if there is no remembered set for it
6023     // because:
6024     // - there can be no references from within humongous starts regions referencing
6025     // the object because we never allocate other objects into them.
6026     // (I.e. there are no intra-region references that may be missed by the
6027     // remembered set)
6028     // - as soon there is a remembered set entry to the humongous starts region
6029     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6030     // until the end of a concurrent mark.
6031     //
6032     // It is not required to check whether the object has been found dead by marking
6033     // or not, in fact it would prevent reclamation within a concurrent cycle, as
6034     // all objects allocated during that time are considered live.
6035     // SATB marking is even more conservative than the remembered set.
6036     // So if at this point in the collection there is no remembered set entry,
6037     // nobody has a reference to it.
6038     // At the start of collection we flush all refinement logs, and remembered sets
6039     // are completely up-to-date wrt to references to the humongous object.
6040     //
6041     // Other implementation considerations:
6042     // - never consider object arrays at this time because they would pose
6043     // considerable effort for cleaning up the the remembered sets. This is
6044     // required because stale remembered sets might reference locations that
6045     // are currently allocated into.
6046     uint region_idx = r->hrm_index();
6047     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6048         !r->rem_set()->is_empty()) {
6049 
6050       if (G1TraceEagerReclaimHumongousObjects) {
6051         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",
6052                                region_idx,
6053                                (size_t)obj->size() * HeapWordSize,
6054                                p2i(r->bottom()),
6055                                r->region_num(),
6056                                r->rem_set()->occupied(),
6057                                r->rem_set()->strong_code_roots_list_length(),
6058                                next_bitmap->isMarked(r->bottom()),
6059                                g1h->is_humongous_reclaim_candidate(region_idx),
6060                                obj->is_typeArray()
6061                               );
6062       }
6063 
6064       return false;
6065     }
6066 
6067     guarantee(obj->is_typeArray(),
6068               err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6069                       PTR_FORMAT " is not.",
6070                       p2i(r->bottom())));
6071 
6072     if (G1TraceEagerReclaimHumongousObjects) {
6073       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",
6074                              region_idx,
6075                              (size_t)obj->size() * HeapWordSize,
6076                              p2i(r->bottom()),
6077                              r->region_num(),
6078                              r->rem_set()->occupied(),
6079                              r->rem_set()->strong_code_roots_list_length(),
6080                              next_bitmap->isMarked(r->bottom()),
6081                              g1h->is_humongous_reclaim_candidate(region_idx),
6082                              obj->is_typeArray()
6083                             );
6084     }
6085     // Need to clear mark bit of the humongous object if already set.
6086     if (next_bitmap->isMarked(r->bottom())) {
6087       next_bitmap->clear(r->bottom());
6088     }
6089     _freed_bytes += r->used();
6090     r->set_containing_set(NULL);
6091     _humongous_regions_removed.increment(1u, r->capacity());
6092     g1h->free_humongous_region(r, _free_region_list, false);
6093 
6094     return false;
6095   }
6096 
6097   HeapRegionSetCount& humongous_free_count() {
6098     return _humongous_regions_removed;
6099   }
6100 
6101   size_t bytes_freed() const {
6102     return _freed_bytes;
6103   }
6104 
6105   size_t humongous_reclaimed() const {
6106     return _humongous_regions_removed.length();
6107   }
6108 };
6109 
6110 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6111   assert_at_safepoint(true);
6112 
6113   if (!G1EagerReclaimHumongousObjects ||
6114       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6115     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6116     return;
6117   }
6118 
6119   double start_time = os::elapsedTime();
6120 
6121   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6122 
6123   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6124   heap_region_iterate(&cl);
6125 
6126   HeapRegionSetCount empty_set;
6127   remove_from_old_sets(empty_set, cl.humongous_free_count());
6128 
6129   G1HRPrinter* hrp = hr_printer();
6130   if (hrp->is_active()) {
6131     FreeRegionListIterator iter(&local_cleanup_list);
6132     while (iter.more_available()) {
6133       HeapRegion* hr = iter.get_next();
6134       hrp->cleanup(hr);
6135     }
6136   }
6137 
6138   prepend_to_freelist(&local_cleanup_list);
6139   decrement_summary_bytes(cl.bytes_freed());
6140 
6141   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6142                                                                     cl.humongous_reclaimed());
6143 }
6144 
6145 // This routine is similar to the above but does not record
6146 // any policy statistics or update free lists; we are abandoning
6147 // the current incremental collection set in preparation of a
6148 // full collection. After the full GC we will start to build up
6149 // the incremental collection set again.
6150 // This is only called when we're doing a full collection
6151 // and is immediately followed by the tearing down of the young list.
6152 
6153 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6154   HeapRegion* cur = cs_head;
6155 
6156   while (cur != NULL) {
6157     HeapRegion* next = cur->next_in_collection_set();
6158     assert(cur->in_collection_set(), "bad CS");
6159     cur->set_next_in_collection_set(NULL);
6160     clear_in_cset(cur);
6161     cur->set_young_index_in_cset(-1);
6162     cur = next;
6163   }
6164 }
6165 
6166 void G1CollectedHeap::set_free_regions_coming() {
6167   if (G1ConcRegionFreeingVerbose) {
6168     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6169                            "setting free regions coming");
6170   }
6171 
6172   assert(!free_regions_coming(), "pre-condition");
6173   _free_regions_coming = true;
6174 }
6175 
6176 void G1CollectedHeap::reset_free_regions_coming() {
6177   assert(free_regions_coming(), "pre-condition");
6178 
6179   {
6180     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6181     _free_regions_coming = false;
6182     SecondaryFreeList_lock->notify_all();
6183   }
6184 
6185   if (G1ConcRegionFreeingVerbose) {
6186     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6187                            "reset free regions coming");
6188   }
6189 }
6190 
6191 void G1CollectedHeap::wait_while_free_regions_coming() {
6192   // Most of the time we won't have to wait, so let's do a quick test
6193   // first before we take the lock.
6194   if (!free_regions_coming()) {
6195     return;
6196   }
6197 
6198   if (G1ConcRegionFreeingVerbose) {
6199     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6200                            "waiting for free regions");
6201   }
6202 
6203   {
6204     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6205     while (free_regions_coming()) {
6206       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6207     }
6208   }
6209 
6210   if (G1ConcRegionFreeingVerbose) {
6211     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6212                            "done waiting for free regions");
6213   }
6214 }
6215 
6216 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6217   _young_list->push_region(hr);
6218 }
6219 
6220 class NoYoungRegionsClosure: public HeapRegionClosure {
6221 private:
6222   bool _success;
6223 public:
6224   NoYoungRegionsClosure() : _success(true) { }
6225   bool doHeapRegion(HeapRegion* r) {
6226     if (r->is_young()) {
6227       gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6228                              p2i(r->bottom()), p2i(r->end()));
6229       _success = false;
6230     }
6231     return false;
6232   }
6233   bool success() { return _success; }
6234 };
6235 
6236 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6237   bool ret = _young_list->check_list_empty(check_sample);
6238 
6239   if (check_heap) {
6240     NoYoungRegionsClosure closure;
6241     heap_region_iterate(&closure);
6242     ret = ret && closure.success();
6243   }
6244 
6245   return ret;
6246 }
6247 
6248 class TearDownRegionSetsClosure : public HeapRegionClosure {
6249 private:
6250   HeapRegionSet *_old_set;
6251 
6252 public:
6253   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6254 
6255   bool doHeapRegion(HeapRegion* r) {
6256     if (r->is_old()) {
6257       _old_set->remove(r);
6258     } else {
6259       // We ignore free regions, we'll empty the free list afterwards.
6260       // We ignore young regions, we'll empty the young list afterwards.
6261       // We ignore humongous regions, we're not tearing down the
6262       // humongous regions set.
6263       assert(r->is_free() || r->is_young() || r->is_humongous(),
6264              "it cannot be another type");
6265     }
6266     return false;
6267   }
6268 
6269   ~TearDownRegionSetsClosure() {
6270     assert(_old_set->is_empty(), "post-condition");
6271   }
6272 };
6273 
6274 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6275   assert_at_safepoint(true /* should_be_vm_thread */);
6276 
6277   if (!free_list_only) {
6278     TearDownRegionSetsClosure cl(&_old_set);
6279     heap_region_iterate(&cl);
6280 
6281     // Note that emptying the _young_list is postponed and instead done as
6282     // the first step when rebuilding the regions sets again. The reason for
6283     // this is that during a full GC string deduplication needs to know if
6284     // a collected region was young or old when the full GC was initiated.
6285   }
6286   _hrm.remove_all_free_regions();
6287 }
6288 
6289 void G1CollectedHeap::increase_used(size_t bytes) {
6290   _summary_bytes_used += bytes;
6291 }
6292 
6293 void G1CollectedHeap::decrease_used(size_t bytes) {
6294   assert(_summary_bytes_used >= bytes,
6295          err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6296                  _summary_bytes_used, bytes));
6297   _summary_bytes_used -= bytes;
6298 }
6299 
6300 void G1CollectedHeap::set_used(size_t bytes) {
6301   _summary_bytes_used = bytes;
6302 }
6303 
6304 class RebuildRegionSetsClosure : public HeapRegionClosure {
6305 private:
6306   bool            _free_list_only;
6307   HeapRegionSet*   _old_set;
6308   HeapRegionManager*   _hrm;
6309   size_t          _total_used;
6310 
6311 public:
6312   RebuildRegionSetsClosure(bool free_list_only,
6313                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6314     _free_list_only(free_list_only),
6315     _old_set(old_set), _hrm(hrm), _total_used(0) {
6316     assert(_hrm->num_free_regions() == 0, "pre-condition");
6317     if (!free_list_only) {
6318       assert(_old_set->is_empty(), "pre-condition");
6319     }
6320   }
6321 
6322   bool doHeapRegion(HeapRegion* r) {
6323     if (r->is_continues_humongous()) {
6324       return false;
6325     }
6326 
6327     if (r->is_empty()) {
6328       // Add free regions to the free list
6329       r->set_free();
6330       r->set_allocation_context(AllocationContext::system());
6331       _hrm->insert_into_free_list(r);
6332     } else if (!_free_list_only) {
6333       assert(!r->is_young(), "we should not come across young regions");
6334 
6335       if (r->is_humongous()) {
6336         // We ignore humongous regions. We left the humongous set unchanged.
6337       } else {
6338         // Objects that were compacted would have ended up on regions
6339         // that were previously old or free.  Archive regions (which are
6340         // old) will not have been touched.
6341         assert(r->is_free() || r->is_old(), "invariant");
6342         // We now consider them old, so register as such. Leave
6343         // archive regions set that way, however, while still adding
6344         // them to the old set.
6345         if (!r->is_archive()) {
6346           r->set_old();
6347         }
6348         _old_set->add(r);
6349       }
6350       _total_used += r->used();
6351     }
6352 
6353     return false;
6354   }
6355 
6356   size_t total_used() {
6357     return _total_used;
6358   }
6359 };
6360 
6361 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6362   assert_at_safepoint(true /* should_be_vm_thread */);
6363 
6364   if (!free_list_only) {
6365     _young_list->empty_list();
6366   }
6367 
6368   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6369   heap_region_iterate(&cl);
6370 
6371   if (!free_list_only) {
6372     set_used(cl.total_used());
6373     if (_archive_allocator != NULL) {
6374       _archive_allocator->clear_used();
6375     }
6376   }
6377   assert(used_unlocked() == recalculate_used(),
6378          err_msg("inconsistent used_unlocked(), "
6379                  "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6380                  used_unlocked(), recalculate_used()));
6381 }
6382 
6383 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6384   _refine_cte_cl->set_concurrent(concurrent);
6385 }
6386 
6387 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6388   HeapRegion* hr = heap_region_containing(p);
6389   return hr->is_in(p);
6390 }
6391 
6392 // Methods for the mutator alloc region
6393 
6394 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6395                                                       bool force) {
6396   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6397   assert(!force || g1_policy()->can_expand_young_list(),
6398          "if force is true we should be able to expand the young list");
6399   bool young_list_full = g1_policy()->is_young_list_full();
6400   if (force || !young_list_full) {
6401     HeapRegion* new_alloc_region = new_region(word_size,
6402                                               false /* is_old */,
6403                                               false /* do_expand */);
6404     if (new_alloc_region != NULL) {
6405       set_region_short_lived_locked(new_alloc_region);
6406       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6407       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6408       return new_alloc_region;
6409     }
6410   }
6411   return NULL;
6412 }
6413 
6414 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6415                                                   size_t allocated_bytes) {
6416   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6417   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6418 
6419   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6420   increase_used(allocated_bytes);
6421   _hr_printer.retire(alloc_region);
6422   // We update the eden sizes here, when the region is retired,
6423   // instead of when it's allocated, since this is the point that its
6424   // used space has been recored in _summary_bytes_used.
6425   g1mm()->update_eden_size();
6426 }
6427 
6428 // Methods for the GC alloc regions
6429 
6430 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6431                                                  uint count,
6432                                                  InCSetState dest) {
6433   assert(FreeList_lock->owned_by_self(), "pre-condition");
6434 
6435   if (count < g1_policy()->max_regions(dest)) {
6436     const bool is_survivor = (dest.is_young());
6437     HeapRegion* new_alloc_region = new_region(word_size,
6438                                               !is_survivor,
6439                                               true /* do_expand */);
6440     if (new_alloc_region != NULL) {
6441       // We really only need to do this for old regions given that we
6442       // should never scan survivors. But it doesn't hurt to do it
6443       // for survivors too.
6444       new_alloc_region->record_timestamp();
6445       if (is_survivor) {
6446         new_alloc_region->set_survivor();
6447         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6448         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6449       } else {
6450         new_alloc_region->set_old();
6451         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6452         check_bitmaps("Old Region Allocation", new_alloc_region);
6453       }
6454       bool during_im = collector_state()->during_initial_mark_pause();
6455       new_alloc_region->note_start_of_copying(during_im);
6456       return new_alloc_region;
6457     }
6458   }
6459   return NULL;
6460 }
6461 
6462 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6463                                              size_t allocated_bytes,
6464                                              InCSetState dest) {
6465   bool during_im = collector_state()->during_initial_mark_pause();
6466   alloc_region->note_end_of_copying(during_im);
6467   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6468   if (dest.is_young()) {
6469     young_list()->add_survivor_region(alloc_region);
6470   } else {
6471     _old_set.add(alloc_region);
6472   }
6473   _hr_printer.retire(alloc_region);
6474 }
6475 
6476 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6477   bool expanded = false;
6478   uint index = _hrm.find_highest_free(&expanded);
6479 
6480   if (index != G1_NO_HRM_INDEX) {
6481     if (expanded) {
6482       ergo_verbose1(ErgoHeapSizing,
6483                     "attempt heap expansion",
6484                     ergo_format_reason("requested address range outside heap bounds")
6485                     ergo_format_byte("region size"),
6486                     HeapRegion::GrainWords * HeapWordSize);
6487     }
6488     _hrm.allocate_free_regions_starting_at(index, 1);
6489     return region_at(index);
6490   }
6491   return NULL;
6492 }
6493 
6494 
6495 // Heap region set verification
6496 
6497 class VerifyRegionListsClosure : public HeapRegionClosure {
6498 private:
6499   HeapRegionSet*   _old_set;
6500   HeapRegionSet*   _humongous_set;
6501   HeapRegionManager*   _hrm;
6502 
6503 public:
6504   HeapRegionSetCount _old_count;
6505   HeapRegionSetCount _humongous_count;
6506   HeapRegionSetCount _free_count;
6507 
6508   VerifyRegionListsClosure(HeapRegionSet* old_set,
6509                            HeapRegionSet* humongous_set,
6510                            HeapRegionManager* hrm) :
6511     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6512     _old_count(), _humongous_count(), _free_count(){ }
6513 
6514   bool doHeapRegion(HeapRegion* hr) {
6515     if (hr->is_continues_humongous()) {
6516       return false;
6517     }
6518 
6519     if (hr->is_young()) {
6520       // TODO
6521     } else if (hr->is_starts_humongous()) {
6522       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6523       _humongous_count.increment(1u, hr->capacity());
6524     } else if (hr->is_empty()) {
6525       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6526       _free_count.increment(1u, hr->capacity());
6527     } else if (hr->is_old()) {
6528       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6529       _old_count.increment(1u, hr->capacity());
6530     } else {
6531       // There are no other valid region types. Check for one invalid
6532       // one we can identify: pinned without old or humongous set.
6533       assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6534       ShouldNotReachHere();
6535     }
6536     return false;
6537   }
6538 
6539   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6540     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6541     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6542         old_set->total_capacity_bytes(), _old_count.capacity()));
6543 
6544     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6545     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6546         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6547 
6548     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()));
6549     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6550         free_list->total_capacity_bytes(), _free_count.capacity()));
6551   }
6552 };
6553 
6554 void G1CollectedHeap::verify_region_sets() {
6555   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6556 
6557   // First, check the explicit lists.
6558   _hrm.verify();
6559   {
6560     // Given that a concurrent operation might be adding regions to
6561     // the secondary free list we have to take the lock before
6562     // verifying it.
6563     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6564     _secondary_free_list.verify_list();
6565   }
6566 
6567   // If a concurrent region freeing operation is in progress it will
6568   // be difficult to correctly attributed any free regions we come
6569   // across to the correct free list given that they might belong to
6570   // one of several (free_list, secondary_free_list, any local lists,
6571   // etc.). So, if that's the case we will skip the rest of the
6572   // verification operation. Alternatively, waiting for the concurrent
6573   // operation to complete will have a non-trivial effect on the GC's
6574   // operation (no concurrent operation will last longer than the
6575   // interval between two calls to verification) and it might hide
6576   // any issues that we would like to catch during testing.
6577   if (free_regions_coming()) {
6578     return;
6579   }
6580 
6581   // Make sure we append the secondary_free_list on the free_list so
6582   // that all free regions we will come across can be safely
6583   // attributed to the free_list.
6584   append_secondary_free_list_if_not_empty_with_lock();
6585 
6586   // Finally, make sure that the region accounting in the lists is
6587   // consistent with what we see in the heap.
6588 
6589   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6590   heap_region_iterate(&cl);
6591   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6592 }
6593 
6594 // Optimized nmethod scanning
6595 
6596 class RegisterNMethodOopClosure: public OopClosure {
6597   G1CollectedHeap* _g1h;
6598   nmethod* _nm;
6599 
6600   template <class T> void do_oop_work(T* p) {
6601     T heap_oop = oopDesc::load_heap_oop(p);
6602     if (!oopDesc::is_null(heap_oop)) {
6603       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6604       HeapRegion* hr = _g1h->heap_region_containing(obj);
6605       assert(!hr->is_continues_humongous(),
6606              err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6607                      " starting at " HR_FORMAT,
6608                      p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6609 
6610       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6611       hr->add_strong_code_root_locked(_nm);
6612     }
6613   }
6614 
6615 public:
6616   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6617     _g1h(g1h), _nm(nm) {}
6618 
6619   void do_oop(oop* p)       { do_oop_work(p); }
6620   void do_oop(narrowOop* p) { do_oop_work(p); }
6621 };
6622 
6623 class UnregisterNMethodOopClosure: public OopClosure {
6624   G1CollectedHeap* _g1h;
6625   nmethod* _nm;
6626 
6627   template <class T> void do_oop_work(T* p) {
6628     T heap_oop = oopDesc::load_heap_oop(p);
6629     if (!oopDesc::is_null(heap_oop)) {
6630       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6631       HeapRegion* hr = _g1h->heap_region_containing(obj);
6632       assert(!hr->is_continues_humongous(),
6633              err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6634                      " starting at " HR_FORMAT,
6635                      p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6636 
6637       hr->remove_strong_code_root(_nm);
6638     }
6639   }
6640 
6641 public:
6642   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6643     _g1h(g1h), _nm(nm) {}
6644 
6645   void do_oop(oop* p)       { do_oop_work(p); }
6646   void do_oop(narrowOop* p) { do_oop_work(p); }
6647 };
6648 
6649 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6650   CollectedHeap::register_nmethod(nm);
6651 
6652   guarantee(nm != NULL, "sanity");
6653   RegisterNMethodOopClosure reg_cl(this, nm);
6654   nm->oops_do(&reg_cl);
6655 }
6656 
6657 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6658   CollectedHeap::unregister_nmethod(nm);
6659 
6660   guarantee(nm != NULL, "sanity");
6661   UnregisterNMethodOopClosure reg_cl(this, nm);
6662   nm->oops_do(&reg_cl, true);
6663 }
6664 
6665 void G1CollectedHeap::purge_code_root_memory() {
6666   double purge_start = os::elapsedTime();
6667   G1CodeRootSet::purge();
6668   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6669   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6670 }
6671 
6672 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6673   G1CollectedHeap* _g1h;
6674 
6675 public:
6676   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6677     _g1h(g1h) {}
6678 
6679   void do_code_blob(CodeBlob* cb) {
6680     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6681     if (nm == NULL) {
6682       return;
6683     }
6684 
6685     if (ScavengeRootsInCode) {
6686       _g1h->register_nmethod(nm);
6687     }
6688   }
6689 };
6690 
6691 void G1CollectedHeap::rebuild_strong_code_roots() {
6692   RebuildStrongCodeRootClosure blob_cl(this);
6693   CodeCache::blobs_do(&blob_cl);
6694 }