rev 7992 : G1RootProcessor
rev 7993 : Convert G1 to G1RootProcessor
rev 7996 : imported patch trace-metadata-comment
rev 7998 : imported patch thomas-comments
rev 7999 : imported patch eriks-comments

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



5472     G1ParTask g1_par_task(this, _task_queues, &root_processor);
5473     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5474     if (g1_policy()->during_initial_mark_pause()) {
5475       ClassLoaderDataGraph::clear_claimed_marks();
5476     }
5477 
5478      // The individual threads will set their evac-failure closures.
5479      if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5480      // These tasks use ShareHeap::_process_strong_tasks
5481      assert(UseDynamicNumberOfGCThreads ||
5482             workers()->active_workers() == workers()->total_workers(),
5483             "If not dynamic should be using all the  workers");
5484     workers()->run_task(&g1_par_task);
5485     end_par_time_sec = os::elapsedTime();
5486 
5487     // Closing the inner scope will execute the destructor
5488     // for the G1RootProcessor object. We record the current
5489     // elapsed time before closing the scope so that time
5490     // taken for the destructor is NOT included in the
5491     // reported parallel time.
5492   }
5493 
5494   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5495 
5496   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5497   phase_times->record_par_time(par_time_ms);
5498 
5499   double code_root_fixup_time_ms =
5500         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5501   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5502 
5503   set_par_threads(0);
5504 
5505   // Process any discovered reference objects - we have
5506   // to do this _before_ we retire the GC alloc regions
5507   // as we may have to copy some 'reachable' referent
5508   // objects (and their reachable sub-graphs) that were
5509   // not copied during the pause.
5510   process_discovered_references(n_workers);
5511 
5512   if (G1StringDedup::is_enabled()) {
5513     double fixup_start = os::elapsedTime();
5514 
5515     G1STWIsAliveClosure is_alive(this);
5516     G1KeepAliveClosure keep_alive(this);
5517     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5518 
5519     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5520     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5521   }
5522 
5523   _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5524   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5525 
5526   // Reset and re-enable the hot card cache.
5527   // Note the counts for the cards in the regions in the
5528   // collection set are reset when the collection set is freed.
5529   hot_card_cache->reset_hot_cache();
5530   hot_card_cache->set_use_cache(true);
5531 
5532   purge_code_root_memory();
5533 
5534   finalize_for_evac_failure();
5535 
5536   if (evacuation_failed()) {
5537     remove_self_forwarding_pointers();
5538 
5539     // Reset the G1EvacuationFailureALot counters and flags
5540     // Note: the values are reset only when an actual
5541     // evacuation failure occurs.
5542     NOT_PRODUCT(reset_evacuation_should_fail();)
5543   }
5544 
5545   // Enqueue any remaining references remaining on the STW
5546   // reference processor's discovered lists. We need to do
5547   // this after the card table is cleaned (and verified) as
5548   // the act of enqueueing entries on to the pending list
5549   // will log these updates (and dirty their associated
5550   // cards). We need these updates logged to update any
5551   // RSets.
5552   enqueue_discovered_references(n_workers);
5553 
5554   redirty_logged_cards();
5555   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5556 }
5557 
5558 void G1CollectedHeap::free_region(HeapRegion* hr,
5559                                   FreeRegionList* free_list,
5560                                   bool par,
5561                                   bool locked) {
5562   assert(!hr->is_free(), "the region should not be free");
5563   assert(!hr->is_empty(), "the region should not be empty");
5564   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5565   assert(free_list != NULL, "pre-condition");
5566 
5567   if (G1VerifyBitmaps) {
5568     MemRegion mr(hr->bottom(), hr->end());
5569     concurrent_mark()->clearRangePrevBitmap(mr);
5570   }
5571 
5572   // Clear the card counts for this region.
5573   // Note: we only need to do this if the region is not young
5574   // (since we don't refine cards in young regions).
5575   if (!hr->is_young()) {
5576     _cg1r->hot_card_cache()->reset_card_counts(hr);
5577   }
5578   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5579   free_list->add_ordered(hr);
5580 }
5581 
5582 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5583                                      FreeRegionList* free_list,
5584                                      bool par) {
5585   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5586   assert(free_list != NULL, "pre-condition");
5587 
5588   size_t hr_capacity = hr->capacity();
5589   // We need to read this before we make the region non-humongous,
5590   // otherwise the information will be gone.
5591   uint last_index = hr->last_hc_index();
5592   hr->clear_humongous();
5593   free_region(hr, free_list, par);
5594 
5595   uint i = hr->hrm_index() + 1;
5596   while (i < last_index) {
5597     HeapRegion* curr_hr = region_at(i);
5598     assert(curr_hr->is_continues_humongous(), "invariant");
5599     curr_hr->clear_humongous();
5600     free_region(curr_hr, free_list, par);
5601     i += 1;
5602   }
5603 }
5604 
5605 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5606                                        const HeapRegionSetCount& humongous_regions_removed) {
5607   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5608     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5609     _old_set.bulk_remove(old_regions_removed);
5610     _humongous_set.bulk_remove(humongous_regions_removed);
5611   }
5612 
5613 }
5614 
5615 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5616   assert(list != NULL, "list can't be null");
5617   if (!list->is_empty()) {
5618     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5619     _hrm.insert_list_into_free_list(list);
5620   }
5621 }
5622 
5623 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5624   _allocator->decrease_used(bytes);
5625 }
5626 
5627 class G1ParCleanupCTTask : public AbstractGangTask {
5628   G1SATBCardTableModRefBS* _ct_bs;
5629   G1CollectedHeap* _g1h;
5630   HeapRegion* volatile _su_head;
5631 public:
5632   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5633                      G1CollectedHeap* g1h) :
5634     AbstractGangTask("G1 Par Cleanup CT Task"),
5635     _ct_bs(ct_bs), _g1h(g1h) { }
5636 
5637   void work(uint worker_id) {
5638     HeapRegion* r;
5639     while (r = _g1h->pop_dirty_cards_region()) {
5640       clear_cards(r);
5641     }
5642   }
5643 
5644   void clear_cards(HeapRegion* r) {
5645     // Cards of the survivors should have already been dirtied.
5646     if (!r->is_survivor()) {
5647       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5648     }
5649   }
5650 };
5651 
5652 #ifndef PRODUCT
5653 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5654   G1CollectedHeap* _g1h;
5655   G1SATBCardTableModRefBS* _ct_bs;
5656 public:
5657   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5658     : _g1h(g1h), _ct_bs(ct_bs) { }
5659   virtual bool doHeapRegion(HeapRegion* r) {
5660     if (r->is_survivor()) {
5661       _g1h->verify_dirty_region(r);
5662     } else {
5663       _g1h->verify_not_dirty_region(r);
5664     }
5665     return false;
5666   }
5667 };
5668 
5669 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5670   // All of the region should be clean.
5671   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5672   MemRegion mr(hr->bottom(), hr->end());
5673   ct_bs->verify_not_dirty_region(mr);
5674 }
5675 
5676 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5677   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5678   // dirty allocated blocks as they allocate them. The thread that
5679   // retires each region and replaces it with a new one will do a
5680   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5681   // not dirty that area (one less thing to have to do while holding
5682   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5683   // is dirty.
5684   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5685   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5686   if (hr->is_young()) {
5687     ct_bs->verify_g1_young_region(mr);
5688   } else {
5689     ct_bs->verify_dirty_region(mr);
5690   }
5691 }
5692 
5693 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5694   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5695   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5696     verify_dirty_region(hr);
5697   }
5698 }
5699 
5700 void G1CollectedHeap::verify_dirty_young_regions() {
5701   verify_dirty_young_list(_young_list->first_region());
5702 }
5703 
5704 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5705                                                HeapWord* tams, HeapWord* end) {
5706   guarantee(tams <= end,
5707             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5708   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5709   if (result < end) {
5710     gclog_or_tty->cr();
5711     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5712                            bitmap_name, result);
5713     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5714                            bitmap_name, tams, end);
5715     return false;
5716   }
5717   return true;
5718 }
5719 
5720 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5721   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5722   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5723 
5724   HeapWord* bottom = hr->bottom();
5725   HeapWord* ptams  = hr->prev_top_at_mark_start();
5726   HeapWord* ntams  = hr->next_top_at_mark_start();
5727   HeapWord* end    = hr->end();
5728 
5729   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5730 
5731   bool res_n = true;
5732   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5733   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5734   // if we happen to be in that state.
5735   if (mark_in_progress() || !_cmThread->in_progress()) {
5736     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5737   }
5738   if (!res_p || !res_n) {
5739     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5740                            HR_FORMAT_PARAMS(hr));
5741     gclog_or_tty->print_cr("#### Caller: %s", caller);
5742     return false;
5743   }
5744   return true;
5745 }
5746 
5747 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5748   if (!G1VerifyBitmaps) return;
5749 
5750   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5751 }
5752 
5753 class G1VerifyBitmapClosure : public HeapRegionClosure {
5754 private:
5755   const char* _caller;
5756   G1CollectedHeap* _g1h;
5757   bool _failures;
5758 
5759 public:
5760   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5761     _caller(caller), _g1h(g1h), _failures(false) { }
5762 
5763   bool failures() { return _failures; }
5764 
5765   virtual bool doHeapRegion(HeapRegion* hr) {
5766     if (hr->is_continues_humongous()) return false;
5767 
5768     bool result = _g1h->verify_bitmaps(_caller, hr);
5769     if (!result) {
5770       _failures = true;
5771     }
5772     return false;
5773   }
5774 };
5775 
5776 void G1CollectedHeap::check_bitmaps(const char* caller) {
5777   if (!G1VerifyBitmaps) return;
5778 
5779   G1VerifyBitmapClosure cl(caller, this);
5780   heap_region_iterate(&cl);
5781   guarantee(!cl.failures(), "bitmap verification");
5782 }
5783 
5784 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5785  private:
5786   bool _failures;
5787  public:
5788   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5789 
5790   virtual bool doHeapRegion(HeapRegion* hr) {
5791     uint i = hr->hrm_index();
5792     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5793     if (hr->is_humongous()) {
5794       if (hr->in_collection_set()) {
5795         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5796         _failures = true;
5797         return true;
5798       }
5799       if (cset_state.is_in_cset()) {
5800         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5801         _failures = true;
5802         return true;
5803       }
5804       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5805         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5806         _failures = true;
5807         return true;
5808       }
5809     } else {
5810       if (cset_state.is_humongous()) {
5811         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5812         _failures = true;
5813         return true;
5814       }
5815       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5816         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5817                                hr->in_collection_set(), cset_state.value(), i);
5818         _failures = true;
5819         return true;
5820       }
5821       if (cset_state.is_in_cset()) {
5822         if (hr->is_young() != (cset_state.is_young())) {
5823           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5824                                  hr->is_young(), cset_state.value(), i);
5825           _failures = true;
5826           return true;
5827         }
5828         if (hr->is_old() != (cset_state.is_old())) {
5829           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5830                                  hr->is_old(), cset_state.value(), i);
5831           _failures = true;
5832           return true;
5833         }
5834       }
5835     }
5836     return false;
5837   }
5838 
5839   bool failures() const { return _failures; }
5840 };
5841 
5842 bool G1CollectedHeap::check_cset_fast_test() {
5843   G1CheckCSetFastTableClosure cl;
5844   _hrm.iterate(&cl);
5845   return !cl.failures();
5846 }
5847 #endif // PRODUCT
5848 
5849 void G1CollectedHeap::cleanUpCardTable() {
5850   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5851   double start = os::elapsedTime();
5852 
5853   {
5854     // Iterate over the dirty cards region list.
5855     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5856 
5857     set_par_threads();
5858     workers()->run_task(&cleanup_task);
5859     set_par_threads(0);
5860 #ifndef PRODUCT
5861     if (G1VerifyCTCleanup || VerifyAfterGC) {
5862       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5863       heap_region_iterate(&cleanup_verifier);
5864     }
5865 #endif
5866   }
5867 
5868   double elapsed = os::elapsedTime() - start;
5869   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5870 }
5871 
5872 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5873   size_t pre_used = 0;
5874   FreeRegionList local_free_list("Local List for CSet Freeing");
5875 
5876   double young_time_ms     = 0.0;
5877   double non_young_time_ms = 0.0;
5878 
5879   // Since the collection set is a superset of the the young list,
5880   // all we need to do to clear the young list is clear its
5881   // head and length, and unlink any young regions in the code below
5882   _young_list->clear();
5883 
5884   G1CollectorPolicy* policy = g1_policy();
5885 
5886   double start_sec = os::elapsedTime();
5887   bool non_young = true;
5888 
5889   HeapRegion* cur = cs_head;
5890   int age_bound = -1;
5891   size_t rs_lengths = 0;
5892 
5893   while (cur != NULL) {
5894     assert(!is_on_master_free_list(cur), "sanity");
5895     if (non_young) {
5896       if (cur->is_young()) {
5897         double end_sec = os::elapsedTime();
5898         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5899         non_young_time_ms += elapsed_ms;
5900 
5901         start_sec = os::elapsedTime();
5902         non_young = false;
5903       }
5904     } else {
5905       if (!cur->is_young()) {
5906         double end_sec = os::elapsedTime();
5907         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5908         young_time_ms += elapsed_ms;
5909 
5910         start_sec = os::elapsedTime();
5911         non_young = true;
5912       }
5913     }
5914 
5915     rs_lengths += cur->rem_set()->occupied_locked();
5916 
5917     HeapRegion* next = cur->next_in_collection_set();
5918     assert(cur->in_collection_set(), "bad CS");
5919     cur->set_next_in_collection_set(NULL);
5920     clear_in_cset(cur);
5921 
5922     if (cur->is_young()) {
5923       int index = cur->young_index_in_cset();
5924       assert(index != -1, "invariant");
5925       assert((uint) index < policy->young_cset_region_length(), "invariant");
5926       size_t words_survived = _surviving_young_words[index];
5927       cur->record_surv_words_in_group(words_survived);
5928 
5929       // At this point the we have 'popped' cur from the collection set
5930       // (linked via next_in_collection_set()) but it is still in the
5931       // young list (linked via next_young_region()). Clear the
5932       // _next_young_region field.
5933       cur->set_next_young_region(NULL);
5934     } else {
5935       int index = cur->young_index_in_cset();
5936       assert(index == -1, "invariant");
5937     }
5938 
5939     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5940             (!cur->is_young() && cur->young_index_in_cset() == -1),
5941             "invariant" );
5942 
5943     if (!cur->evacuation_failed()) {
5944       MemRegion used_mr = cur->used_region();
5945 
5946       // And the region is empty.
5947       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5948       pre_used += cur->used();
5949       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5950     } else {
5951       cur->uninstall_surv_rate_group();
5952       if (cur->is_young()) {
5953         cur->set_young_index_in_cset(-1);
5954       }
5955       cur->set_evacuation_failed(false);
5956       // The region is now considered to be old.
5957       cur->set_old();
5958       _old_set.add(cur);
5959       evacuation_info.increment_collectionset_used_after(cur->used());
5960     }
5961     cur = next;
5962   }
5963 
5964   evacuation_info.set_regions_freed(local_free_list.length());
5965   policy->record_max_rs_lengths(rs_lengths);
5966   policy->cset_regions_freed();
5967 
5968   double end_sec = os::elapsedTime();
5969   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5970 
5971   if (non_young) {
5972     non_young_time_ms += elapsed_ms;
5973   } else {
5974     young_time_ms += elapsed_ms;
5975   }
5976 
5977   prepend_to_freelist(&local_free_list);
5978   decrement_summary_bytes(pre_used);
5979   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5980   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5981 }
5982 
5983 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5984  private:
5985   FreeRegionList* _free_region_list;
5986   HeapRegionSet* _proxy_set;
5987   HeapRegionSetCount _humongous_regions_removed;
5988   size_t _freed_bytes;
5989  public:
5990 
5991   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5992     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5993   }
5994 
5995   virtual bool doHeapRegion(HeapRegion* r) {
5996     if (!r->is_starts_humongous()) {
5997       return false;
5998     }
5999 
6000     G1CollectedHeap* g1h = G1CollectedHeap::heap();
6001 
6002     oop obj = (oop)r->bottom();
6003     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6004 
6005     // The following checks whether the humongous object is live are sufficient.
6006     // The main additional check (in addition to having a reference from the roots
6007     // or the young gen) is whether the humongous object has a remembered set entry.
6008     //
6009     // A humongous object cannot be live if there is no remembered set for it
6010     // because:
6011     // - there can be no references from within humongous starts regions referencing
6012     // the object because we never allocate other objects into them.
6013     // (I.e. there are no intra-region references that may be missed by the
6014     // remembered set)
6015     // - as soon there is a remembered set entry to the humongous starts region
6016     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6017     // until the end of a concurrent mark.
6018     //
6019     // It is not required to check whether the object has been found dead by marking
6020     // or not, in fact it would prevent reclamation within a concurrent cycle, as
6021     // all objects allocated during that time are considered live.
6022     // SATB marking is even more conservative than the remembered set.
6023     // So if at this point in the collection there is no remembered set entry,
6024     // nobody has a reference to it.
6025     // At the start of collection we flush all refinement logs, and remembered sets
6026     // are completely up-to-date wrt to references to the humongous object.
6027     //
6028     // Other implementation considerations:
6029     // - never consider object arrays at this time because they would pose
6030     // considerable effort for cleaning up the the remembered sets. This is
6031     // required because stale remembered sets might reference locations that
6032     // are currently allocated into.
6033     uint region_idx = r->hrm_index();
6034     if (g1h->humongous_is_live(region_idx) ||
6035         g1h->humongous_region_is_always_live(region_idx)) {
6036 
6037       if (G1TraceEagerReclaimHumongousObjects) {
6038         gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6039                                region_idx,
6040                                obj->size()*HeapWordSize,
6041                                r->bottom(),
6042                                r->region_num(),
6043                                r->rem_set()->occupied(),
6044                                r->rem_set()->strong_code_roots_list_length(),
6045                                next_bitmap->isMarked(r->bottom()),
6046                                g1h->humongous_is_live(region_idx),
6047                                obj->is_objArray()
6048                               );
6049       }
6050 
6051       return false;
6052     }
6053 
6054     guarantee(!obj->is_objArray(),
6055               err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6056                       r->bottom()));
6057 
6058     if (G1TraceEagerReclaimHumongousObjects) {
6059       gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6060                              region_idx,
6061                              obj->size()*HeapWordSize,
6062                              r->bottom(),
6063                              r->region_num(),
6064                              r->rem_set()->occupied(),
6065                              r->rem_set()->strong_code_roots_list_length(),
6066                              next_bitmap->isMarked(r->bottom()),
6067                              g1h->humongous_is_live(region_idx),
6068                              obj->is_objArray()
6069                             );
6070     }
6071     // Need to clear mark bit of the humongous object if already set.
6072     if (next_bitmap->isMarked(r->bottom())) {
6073       next_bitmap->clear(r->bottom());
6074     }
6075     _freed_bytes += r->used();
6076     r->set_containing_set(NULL);
6077     _humongous_regions_removed.increment(1u, r->capacity());
6078     g1h->free_humongous_region(r, _free_region_list, false);
6079 
6080     return false;
6081   }
6082 
6083   HeapRegionSetCount& humongous_free_count() {
6084     return _humongous_regions_removed;
6085   }
6086 
6087   size_t bytes_freed() const {
6088     return _freed_bytes;
6089   }
6090 
6091   size_t humongous_reclaimed() const {
6092     return _humongous_regions_removed.length();
6093   }
6094 };
6095 
6096 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6097   assert_at_safepoint(true);
6098 
6099   if (!G1EagerReclaimHumongousObjects ||
6100       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6101     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6102     return;
6103   }
6104 
6105   double start_time = os::elapsedTime();
6106 
6107   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6108 
6109   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6110   heap_region_iterate(&cl);
6111 
6112   HeapRegionSetCount empty_set;
6113   remove_from_old_sets(empty_set, cl.humongous_free_count());
6114 
6115   G1HRPrinter* hr_printer = _g1h->hr_printer();
6116   if (hr_printer->is_active()) {
6117     FreeRegionListIterator iter(&local_cleanup_list);
6118     while (iter.more_available()) {
6119       HeapRegion* hr = iter.get_next();
6120       hr_printer->cleanup(hr);
6121     }
6122   }
6123 
6124   prepend_to_freelist(&local_cleanup_list);
6125   decrement_summary_bytes(cl.bytes_freed());
6126 
6127   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6128                                                                     cl.humongous_reclaimed());
6129 }
6130 
6131 // This routine is similar to the above but does not record
6132 // any policy statistics or update free lists; we are abandoning
6133 // the current incremental collection set in preparation of a
6134 // full collection. After the full GC we will start to build up
6135 // the incremental collection set again.
6136 // This is only called when we're doing a full collection
6137 // and is immediately followed by the tearing down of the young list.
6138 
6139 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6140   HeapRegion* cur = cs_head;
6141 
6142   while (cur != NULL) {
6143     HeapRegion* next = cur->next_in_collection_set();
6144     assert(cur->in_collection_set(), "bad CS");
6145     cur->set_next_in_collection_set(NULL);
6146     clear_in_cset(cur);
6147     cur->set_young_index_in_cset(-1);
6148     cur = next;
6149   }
6150 }
6151 
6152 void G1CollectedHeap::set_free_regions_coming() {
6153   if (G1ConcRegionFreeingVerbose) {
6154     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6155                            "setting free regions coming");
6156   }
6157 
6158   assert(!free_regions_coming(), "pre-condition");
6159   _free_regions_coming = true;
6160 }
6161 
6162 void G1CollectedHeap::reset_free_regions_coming() {
6163   assert(free_regions_coming(), "pre-condition");
6164 
6165   {
6166     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6167     _free_regions_coming = false;
6168     SecondaryFreeList_lock->notify_all();
6169   }
6170 
6171   if (G1ConcRegionFreeingVerbose) {
6172     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6173                            "reset free regions coming");
6174   }
6175 }
6176 
6177 void G1CollectedHeap::wait_while_free_regions_coming() {
6178   // Most of the time we won't have to wait, so let's do a quick test
6179   // first before we take the lock.
6180   if (!free_regions_coming()) {
6181     return;
6182   }
6183 
6184   if (G1ConcRegionFreeingVerbose) {
6185     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6186                            "waiting for free regions");
6187   }
6188 
6189   {
6190     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6191     while (free_regions_coming()) {
6192       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6193     }
6194   }
6195 
6196   if (G1ConcRegionFreeingVerbose) {
6197     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6198                            "done waiting for free regions");
6199   }
6200 }
6201 
6202 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6203   assert(heap_lock_held_for_gc(),
6204               "the heap lock should already be held by or for this thread");
6205   _young_list->push_region(hr);
6206 }
6207 
6208 class NoYoungRegionsClosure: public HeapRegionClosure {
6209 private:
6210   bool _success;
6211 public:
6212   NoYoungRegionsClosure() : _success(true) { }
6213   bool doHeapRegion(HeapRegion* r) {
6214     if (r->is_young()) {
6215       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6216                              r->bottom(), r->end());
6217       _success = false;
6218     }
6219     return false;
6220   }
6221   bool success() { return _success; }
6222 };
6223 
6224 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6225   bool ret = _young_list->check_list_empty(check_sample);
6226 
6227   if (check_heap) {
6228     NoYoungRegionsClosure closure;
6229     heap_region_iterate(&closure);
6230     ret = ret && closure.success();
6231   }
6232 
6233   return ret;
6234 }
6235 
6236 class TearDownRegionSetsClosure : public HeapRegionClosure {
6237 private:
6238   HeapRegionSet *_old_set;
6239 
6240 public:
6241   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6242 
6243   bool doHeapRegion(HeapRegion* r) {
6244     if (r->is_old()) {
6245       _old_set->remove(r);
6246     } else {
6247       // We ignore free regions, we'll empty the free list afterwards.
6248       // We ignore young regions, we'll empty the young list afterwards.
6249       // We ignore humongous regions, we're not tearing down the
6250       // humongous regions set.
6251       assert(r->is_free() || r->is_young() || r->is_humongous(),
6252              "it cannot be another type");
6253     }
6254     return false;
6255   }
6256 
6257   ~TearDownRegionSetsClosure() {
6258     assert(_old_set->is_empty(), "post-condition");
6259   }
6260 };
6261 
6262 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6263   assert_at_safepoint(true /* should_be_vm_thread */);
6264 
6265   if (!free_list_only) {
6266     TearDownRegionSetsClosure cl(&_old_set);
6267     heap_region_iterate(&cl);
6268 
6269     // Note that emptying the _young_list is postponed and instead done as
6270     // the first step when rebuilding the regions sets again. The reason for
6271     // this is that during a full GC string deduplication needs to know if
6272     // a collected region was young or old when the full GC was initiated.
6273   }
6274   _hrm.remove_all_free_regions();
6275 }
6276 
6277 class RebuildRegionSetsClosure : public HeapRegionClosure {
6278 private:
6279   bool            _free_list_only;
6280   HeapRegionSet*   _old_set;
6281   HeapRegionManager*   _hrm;
6282   size_t          _total_used;
6283 
6284 public:
6285   RebuildRegionSetsClosure(bool free_list_only,
6286                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6287     _free_list_only(free_list_only),
6288     _old_set(old_set), _hrm(hrm), _total_used(0) {
6289     assert(_hrm->num_free_regions() == 0, "pre-condition");
6290     if (!free_list_only) {
6291       assert(_old_set->is_empty(), "pre-condition");
6292     }
6293   }
6294 
6295   bool doHeapRegion(HeapRegion* r) {
6296     if (r->is_continues_humongous()) {
6297       return false;
6298     }
6299 
6300     if (r->is_empty()) {
6301       // Add free regions to the free list
6302       r->set_free();
6303       r->set_allocation_context(AllocationContext::system());
6304       _hrm->insert_into_free_list(r);
6305     } else if (!_free_list_only) {
6306       assert(!r->is_young(), "we should not come across young regions");
6307 
6308       if (r->is_humongous()) {
6309         // We ignore humongous regions, we left the humongous set unchanged
6310       } else {
6311         // Objects that were compacted would have ended up on regions
6312         // that were previously old or free.
6313         assert(r->is_free() || r->is_old(), "invariant");
6314         // We now consider them old, so register as such.
6315         r->set_old();
6316         _old_set->add(r);
6317       }
6318       _total_used += r->used();
6319     }
6320 
6321     return false;
6322   }
6323 
6324   size_t total_used() {
6325     return _total_used;
6326   }
6327 };
6328 
6329 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6330   assert_at_safepoint(true /* should_be_vm_thread */);
6331 
6332   if (!free_list_only) {
6333     _young_list->empty_list();
6334   }
6335 
6336   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6337   heap_region_iterate(&cl);
6338 
6339   if (!free_list_only) {
6340     _allocator->set_used(cl.total_used());
6341   }
6342   assert(_allocator->used_unlocked() == recalculate_used(),
6343          err_msg("inconsistent _allocator->used_unlocked(), "
6344                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6345                  _allocator->used_unlocked(), recalculate_used()));
6346 }
6347 
6348 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6349   _refine_cte_cl->set_concurrent(concurrent);
6350 }
6351 
6352 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6353   HeapRegion* hr = heap_region_containing(p);
6354   return hr->is_in(p);
6355 }
6356 
6357 // Methods for the mutator alloc region
6358 
6359 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6360                                                       bool force) {
6361   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6362   assert(!force || g1_policy()->can_expand_young_list(),
6363          "if force is true we should be able to expand the young list");
6364   bool young_list_full = g1_policy()->is_young_list_full();
6365   if (force || !young_list_full) {
6366     HeapRegion* new_alloc_region = new_region(word_size,
6367                                               false /* is_old */,
6368                                               false /* do_expand */);
6369     if (new_alloc_region != NULL) {
6370       set_region_short_lived_locked(new_alloc_region);
6371       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6372       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6373       return new_alloc_region;
6374     }
6375   }
6376   return NULL;
6377 }
6378 
6379 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6380                                                   size_t allocated_bytes) {
6381   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6382   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6383 
6384   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6385   _allocator->increase_used(allocated_bytes);
6386   _hr_printer.retire(alloc_region);
6387   // We update the eden sizes here, when the region is retired,
6388   // instead of when it's allocated, since this is the point that its
6389   // used space has been recored in _summary_bytes_used.
6390   g1mm()->update_eden_size();
6391 }
6392 
6393 void G1CollectedHeap::set_par_threads() {
6394   // Don't change the number of workers.  Use the value previously set
6395   // in the workgroup.
6396   uint n_workers = workers()->active_workers();
6397   assert(UseDynamicNumberOfGCThreads ||
6398            n_workers == workers()->total_workers(),
6399       "Otherwise should be using the total number of workers");
6400   if (n_workers == 0) {
6401     assert(false, "Should have been set in prior evacuation pause.");
6402     n_workers = ParallelGCThreads;
6403     workers()->set_active_workers(n_workers);
6404   }
6405   set_par_threads(n_workers);
6406 }
6407 
6408 // Methods for the GC alloc regions
6409 
6410 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6411                                                  uint count,
6412                                                  InCSetState dest) {
6413   assert(FreeList_lock->owned_by_self(), "pre-condition");
6414 
6415   if (count < g1_policy()->max_regions(dest)) {
6416     const bool is_survivor = (dest.is_young());
6417     HeapRegion* new_alloc_region = new_region(word_size,
6418                                               !is_survivor,
6419                                               true /* do_expand */);
6420     if (new_alloc_region != NULL) {
6421       // We really only need to do this for old regions given that we
6422       // should never scan survivors. But it doesn't hurt to do it
6423       // for survivors too.
6424       new_alloc_region->record_timestamp();
6425       if (is_survivor) {
6426         new_alloc_region->set_survivor();
6427         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6428         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6429       } else {
6430         new_alloc_region->set_old();
6431         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6432         check_bitmaps("Old Region Allocation", new_alloc_region);
6433       }
6434       bool during_im = g1_policy()->during_initial_mark_pause();
6435       new_alloc_region->note_start_of_copying(during_im);
6436       return new_alloc_region;
6437     }
6438   }
6439   return NULL;
6440 }
6441 
6442 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6443                                              size_t allocated_bytes,
6444                                              InCSetState dest) {
6445   bool during_im = g1_policy()->during_initial_mark_pause();
6446   alloc_region->note_end_of_copying(during_im);
6447   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6448   if (dest.is_young()) {
6449     young_list()->add_survivor_region(alloc_region);
6450   } else {
6451     _old_set.add(alloc_region);
6452   }
6453   _hr_printer.retire(alloc_region);
6454 }
6455 
6456 // Heap region set verification
6457 
6458 class VerifyRegionListsClosure : public HeapRegionClosure {
6459 private:
6460   HeapRegionSet*   _old_set;
6461   HeapRegionSet*   _humongous_set;
6462   HeapRegionManager*   _hrm;
6463 
6464 public:
6465   HeapRegionSetCount _old_count;
6466   HeapRegionSetCount _humongous_count;
6467   HeapRegionSetCount _free_count;
6468 
6469   VerifyRegionListsClosure(HeapRegionSet* old_set,
6470                            HeapRegionSet* humongous_set,
6471                            HeapRegionManager* hrm) :
6472     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6473     _old_count(), _humongous_count(), _free_count(){ }
6474 
6475   bool doHeapRegion(HeapRegion* hr) {
6476     if (hr->is_continues_humongous()) {
6477       return false;
6478     }
6479 
6480     if (hr->is_young()) {
6481       // TODO
6482     } else if (hr->is_starts_humongous()) {
6483       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6484       _humongous_count.increment(1u, hr->capacity());
6485     } else if (hr->is_empty()) {
6486       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6487       _free_count.increment(1u, hr->capacity());
6488     } else if (hr->is_old()) {
6489       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6490       _old_count.increment(1u, hr->capacity());
6491     } else {
6492       ShouldNotReachHere();
6493     }
6494     return false;
6495   }
6496 
6497   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6498     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6499     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6500         old_set->total_capacity_bytes(), _old_count.capacity()));
6501 
6502     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6503     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6504         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6505 
6506     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()));
6507     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6508         free_list->total_capacity_bytes(), _free_count.capacity()));
6509   }
6510 };
6511 
6512 void G1CollectedHeap::verify_region_sets() {
6513   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6514 
6515   // First, check the explicit lists.
6516   _hrm.verify();
6517   {
6518     // Given that a concurrent operation might be adding regions to
6519     // the secondary free list we have to take the lock before
6520     // verifying it.
6521     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6522     _secondary_free_list.verify_list();
6523   }
6524 
6525   // If a concurrent region freeing operation is in progress it will
6526   // be difficult to correctly attributed any free regions we come
6527   // across to the correct free list given that they might belong to
6528   // one of several (free_list, secondary_free_list, any local lists,
6529   // etc.). So, if that's the case we will skip the rest of the
6530   // verification operation. Alternatively, waiting for the concurrent
6531   // operation to complete will have a non-trivial effect on the GC's
6532   // operation (no concurrent operation will last longer than the
6533   // interval between two calls to verification) and it might hide
6534   // any issues that we would like to catch during testing.
6535   if (free_regions_coming()) {
6536     return;
6537   }
6538 
6539   // Make sure we append the secondary_free_list on the free_list so
6540   // that all free regions we will come across can be safely
6541   // attributed to the free_list.
6542   append_secondary_free_list_if_not_empty_with_lock();
6543 
6544   // Finally, make sure that the region accounting in the lists is
6545   // consistent with what we see in the heap.
6546 
6547   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6548   heap_region_iterate(&cl);
6549   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6550 }
6551 
6552 // Optimized nmethod scanning
6553 
6554 class RegisterNMethodOopClosure: public OopClosure {
6555   G1CollectedHeap* _g1h;
6556   nmethod* _nm;
6557 
6558   template <class T> void do_oop_work(T* p) {
6559     T heap_oop = oopDesc::load_heap_oop(p);
6560     if (!oopDesc::is_null(heap_oop)) {
6561       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6562       HeapRegion* hr = _g1h->heap_region_containing(obj);
6563       assert(!hr->is_continues_humongous(),
6564              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6565                      " starting at "HR_FORMAT,
6566                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6567 
6568       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6569       hr->add_strong_code_root_locked(_nm);
6570     }
6571   }
6572 
6573 public:
6574   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6575     _g1h(g1h), _nm(nm) {}
6576 
6577   void do_oop(oop* p)       { do_oop_work(p); }
6578   void do_oop(narrowOop* p) { do_oop_work(p); }
6579 };
6580 
6581 class UnregisterNMethodOopClosure: public OopClosure {
6582   G1CollectedHeap* _g1h;
6583   nmethod* _nm;
6584 
6585   template <class T> void do_oop_work(T* p) {
6586     T heap_oop = oopDesc::load_heap_oop(p);
6587     if (!oopDesc::is_null(heap_oop)) {
6588       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6589       HeapRegion* hr = _g1h->heap_region_containing(obj);
6590       assert(!hr->is_continues_humongous(),
6591              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6592                      " starting at "HR_FORMAT,
6593                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6594 
6595       hr->remove_strong_code_root(_nm);
6596     }
6597   }
6598 
6599 public:
6600   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6601     _g1h(g1h), _nm(nm) {}
6602 
6603   void do_oop(oop* p)       { do_oop_work(p); }
6604   void do_oop(narrowOop* p) { do_oop_work(p); }
6605 };
6606 
6607 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6608   CollectedHeap::register_nmethod(nm);
6609 
6610   guarantee(nm != NULL, "sanity");
6611   RegisterNMethodOopClosure reg_cl(this, nm);
6612   nm->oops_do(&reg_cl);
6613 }
6614 
6615 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6616   CollectedHeap::unregister_nmethod(nm);
6617 
6618   guarantee(nm != NULL, "sanity");
6619   UnregisterNMethodOopClosure reg_cl(this, nm);
6620   nm->oops_do(&reg_cl, true);
6621 }
6622 
6623 void G1CollectedHeap::purge_code_root_memory() {
6624   double purge_start = os::elapsedTime();
6625   G1CodeRootSet::purge();
6626   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6627   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6628 }
6629 
6630 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6631   G1CollectedHeap* _g1h;
6632 
6633 public:
6634   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6635     _g1h(g1h) {}
6636 
6637   void do_code_blob(CodeBlob* cb) {
6638     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6639     if (nm == NULL) {
6640       return;
6641     }
6642 
6643     if (ScavengeRootsInCode) {
6644       _g1h->register_nmethod(nm);
6645     }
6646   }
6647 };
6648 
6649 void G1CollectedHeap::rebuild_strong_code_roots() {
6650   RebuildStrongCodeRootClosure blob_cl(this);
6651   CodeCache::blobs_do(&blob_cl);
6652 }
--- EOF ---