1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "code/icBuffer.hpp"
  30 #include "gc/g1/bufferingOopClosure.hpp"
  31 #include "gc/g1/concurrentG1Refine.hpp"
  32 #include "gc/g1/concurrentG1RefineThread.hpp"
  33 #include "gc/g1/concurrentMarkThread.inline.hpp"
  34 #include "gc/g1/g1Allocator.inline.hpp"
  35 #include "gc/g1/g1CollectedHeap.inline.hpp"
  36 #include "gc/g1/g1CollectorPolicy.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ErgoVerbose.hpp"
  39 #include "gc/g1/g1EvacFailure.hpp"
  40 #include "gc/g1/g1GCPhaseTimes.hpp"
  41 #include "gc/g1/g1Log.hpp"
  42 #include "gc/g1/g1MarkSweep.hpp"
  43 #include "gc/g1/g1OopClosures.inline.hpp"
  44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  46 #include "gc/g1/g1RemSet.inline.hpp"
  47 #include "gc/g1/g1RootProcessor.hpp"
  48 #include "gc/g1/g1StringDedup.hpp"
  49 #include "gc/g1/g1YCTypes.hpp"
  50 #include "gc/g1/heapRegion.inline.hpp"
  51 #include "gc/g1/heapRegionRemSet.hpp"
  52 #include "gc/g1/heapRegionSet.inline.hpp"
  53 #include "gc/g1/suspendibleThreadSet.hpp"
  54 #include "gc/g1/vm_operations_g1.hpp"
  55 #include "gc/shared/gcHeapSummary.hpp"
  56 #include "gc/shared/gcLocker.inline.hpp"
  57 #include "gc/shared/gcTimer.hpp"
  58 #include "gc/shared/gcTrace.hpp"
  59 #include "gc/shared/gcTraceTime.hpp"
  60 #include "gc/shared/generationSpec.hpp"
  61 #include "gc/shared/isGCActiveMark.hpp"
  62 #include "gc/shared/referenceProcessor.hpp"
  63 #include "gc/shared/taskqueue.inline.hpp"
  64 #include "memory/allocation.hpp"
  65 #include "memory/iterator.hpp"
  66 #include "oops/oop.inline.hpp"
  67 #include "runtime/atomic.inline.hpp"
  68 #include "runtime/init.hpp"
  69 #include "runtime/orderAccess.inline.hpp"
  70 #include "runtime/vmThread.hpp"
  71 #include "utilities/globalDefinitions.hpp"
  72 #include "utilities/stack.inline.hpp"
  73 
  74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  75 
  76 // INVARIANTS/NOTES
  77 //
  78 // All allocation activity covered by the G1CollectedHeap interface is
  79 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  80 // and allocate_new_tlab, which are the "entry" points to the
  81 // allocation code from the rest of the JVM.  (Note that this does not
  82 // apply to TLAB allocation, which is not part of this interface: it
  83 // is done by clients of this interface.)
  84 
  85 // Local to this file.
  86 
  87 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  88   bool _concurrent;
  89 public:
  90   RefineCardTableEntryClosure() : _concurrent(true) { }
  91 
  92   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  93     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
  94     // This path is executed by the concurrent refine or mutator threads,
  95     // concurrently, and so we do not care if card_ptr contains references
  96     // that point into the collection set.
  97     assert(!oops_into_cset, "should be");
  98 
  99     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 100       // Caller will actually yield.
 101       return false;
 102     }
 103     // Otherwise, we finished successfully; return true.
 104     return true;
 105   }
 106 
 107   void set_concurrent(bool b) { _concurrent = b; }
 108 };
 109 
 110 
 111 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 112  private:
 113   size_t _num_processed;
 114 
 115  public:
 116   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 117 
 118   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 119     *card_ptr = CardTableModRefBS::dirty_card_val();
 120     _num_processed++;
 121     return true;
 122   }
 123 
 124   size_t num_processed() const { return _num_processed; }
 125 };
 126 
 127 YoungList::YoungList(G1CollectedHeap* g1h) :
 128     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 129     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 130   guarantee(check_list_empty(false), "just making sure...");
 131 }
 132 
 133 void YoungList::push_region(HeapRegion *hr) {
 134   assert(!hr->is_young(), "should not already be young");
 135   assert(hr->get_next_young_region() == NULL, "cause it should!");
 136 
 137   hr->set_next_young_region(_head);
 138   _head = hr;
 139 
 140   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 141   ++_length;
 142 }
 143 
 144 void YoungList::add_survivor_region(HeapRegion* hr) {
 145   assert(hr->is_survivor(), "should be flagged as survivor region");
 146   assert(hr->get_next_young_region() == NULL, "cause it should!");
 147 
 148   hr->set_next_young_region(_survivor_head);
 149   if (_survivor_head == NULL) {
 150     _survivor_tail = hr;
 151   }
 152   _survivor_head = hr;
 153   ++_survivor_length;
 154 }
 155 
 156 void YoungList::empty_list(HeapRegion* list) {
 157   while (list != NULL) {
 158     HeapRegion* next = list->get_next_young_region();
 159     list->set_next_young_region(NULL);
 160     list->uninstall_surv_rate_group();
 161     // This is called before a Full GC and all the non-empty /
 162     // non-humongous regions at the end of the Full GC will end up as
 163     // old anyway.
 164     list->set_old();
 165     list = next;
 166   }
 167 }
 168 
 169 void YoungList::empty_list() {
 170   assert(check_list_well_formed(), "young list should be well formed");
 171 
 172   empty_list(_head);
 173   _head = NULL;
 174   _length = 0;
 175 
 176   empty_list(_survivor_head);
 177   _survivor_head = NULL;
 178   _survivor_tail = NULL;
 179   _survivor_length = 0;
 180 
 181   _last_sampled_rs_lengths = 0;
 182 
 183   assert(check_list_empty(false), "just making sure...");
 184 }
 185 
 186 bool YoungList::check_list_well_formed() {
 187   bool ret = true;
 188 
 189   uint length = 0;
 190   HeapRegion* curr = _head;
 191   HeapRegion* last = NULL;
 192   while (curr != NULL) {
 193     if (!curr->is_young()) {
 194       gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
 195                              "incorrectly tagged (y: %d, surv: %d)",
 196                              p2i(curr->bottom()), p2i(curr->end()),
 197                              curr->is_young(), curr->is_survivor());
 198       ret = false;
 199     }
 200     ++length;
 201     last = curr;
 202     curr = curr->get_next_young_region();
 203   }
 204   ret = ret && (length == _length);
 205 
 206   if (!ret) {
 207     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 208     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 209                            length, _length);
 210   }
 211 
 212   return ret;
 213 }
 214 
 215 bool YoungList::check_list_empty(bool check_sample) {
 216   bool ret = true;
 217 
 218   if (_length != 0) {
 219     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 220                   _length);
 221     ret = false;
 222   }
 223   if (check_sample && _last_sampled_rs_lengths != 0) {
 224     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 225     ret = false;
 226   }
 227   if (_head != NULL) {
 228     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 229     ret = false;
 230   }
 231   if (!ret) {
 232     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 233   }
 234 
 235   return ret;
 236 }
 237 
 238 void
 239 YoungList::rs_length_sampling_init() {
 240   _sampled_rs_lengths = 0;
 241   _curr               = _head;
 242 }
 243 
 244 bool
 245 YoungList::rs_length_sampling_more() {
 246   return _curr != NULL;
 247 }
 248 
 249 void
 250 YoungList::rs_length_sampling_next() {
 251   assert( _curr != NULL, "invariant" );
 252   size_t rs_length = _curr->rem_set()->occupied();
 253 
 254   _sampled_rs_lengths += rs_length;
 255 
 256   // The current region may not yet have been added to the
 257   // incremental collection set (it gets added when it is
 258   // retired as the current allocation region).
 259   if (_curr->in_collection_set()) {
 260     // Update the collection set policy information for this region
 261     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 262   }
 263 
 264   _curr = _curr->get_next_young_region();
 265   if (_curr == NULL) {
 266     _last_sampled_rs_lengths = _sampled_rs_lengths;
 267     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 268   }
 269 }
 270 
 271 void
 272 YoungList::reset_auxilary_lists() {
 273   guarantee( is_empty(), "young list should be empty" );
 274   assert(check_list_well_formed(), "young list should be well formed");
 275 
 276   // Add survivor regions to SurvRateGroup.
 277   _g1h->g1_policy()->note_start_adding_survivor_regions();
 278   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 279 
 280   int young_index_in_cset = 0;
 281   for (HeapRegion* curr = _survivor_head;
 282        curr != NULL;
 283        curr = curr->get_next_young_region()) {
 284     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 285 
 286     // The region is a non-empty survivor so let's add it to
 287     // the incremental collection set for the next evacuation
 288     // pause.
 289     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 290     young_index_in_cset += 1;
 291   }
 292   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 293   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 294 
 295   _head   = _survivor_head;
 296   _length = _survivor_length;
 297   if (_survivor_head != NULL) {
 298     assert(_survivor_tail != NULL, "cause it shouldn't be");
 299     assert(_survivor_length > 0, "invariant");
 300     _survivor_tail->set_next_young_region(NULL);
 301   }
 302 
 303   // Don't clear the survivor list handles until the start of
 304   // the next evacuation pause - we need it in order to re-tag
 305   // the survivor regions from this evacuation pause as 'young'
 306   // at the start of the next.
 307 
 308   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 309 
 310   assert(check_list_well_formed(), "young list should be well formed");
 311 }
 312 
 313 void YoungList::print() {
 314   HeapRegion* lists[] = {_head,   _survivor_head};
 315   const char* names[] = {"YOUNG", "SURVIVOR"};
 316 
 317   for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
 318     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 319     HeapRegion *curr = lists[list];
 320     if (curr == NULL)
 321       gclog_or_tty->print_cr("  empty");
 322     while (curr != NULL) {
 323       gclog_or_tty->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
 324                              HR_FORMAT_PARAMS(curr),
 325                              p2i(curr->prev_top_at_mark_start()),
 326                              p2i(curr->next_top_at_mark_start()),
 327                              curr->age_in_surv_rate_group_cond());
 328       curr = curr->get_next_young_region();
 329     }
 330   }
 331 
 332   gclog_or_tty->cr();
 333 }
 334 
 335 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 336   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 337 }
 338 
 339 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 340   // The from card cache is not the memory that is actually committed. So we cannot
 341   // take advantage of the zero_filled parameter.
 342   reset_from_card_cache(start_idx, num_regions);
 343 }
 344 
 345 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 346 {
 347   // Claim the right to put the region on the dirty cards region list
 348   // by installing a self pointer.
 349   HeapRegion* next = hr->get_next_dirty_cards_region();
 350   if (next == NULL) {
 351     HeapRegion* res = (HeapRegion*)
 352       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 353                           NULL);
 354     if (res == NULL) {
 355       HeapRegion* head;
 356       do {
 357         // Put the region to the dirty cards region list.
 358         head = _dirty_cards_region_list;
 359         next = (HeapRegion*)
 360           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 361         if (next == head) {
 362           assert(hr->get_next_dirty_cards_region() == hr,
 363                  "hr->get_next_dirty_cards_region() != hr");
 364           if (next == NULL) {
 365             // The last region in the list points to itself.
 366             hr->set_next_dirty_cards_region(hr);
 367           } else {
 368             hr->set_next_dirty_cards_region(next);
 369           }
 370         }
 371       } while (next != head);
 372     }
 373   }
 374 }
 375 
 376 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 377 {
 378   HeapRegion* head;
 379   HeapRegion* hr;
 380   do {
 381     head = _dirty_cards_region_list;
 382     if (head == NULL) {
 383       return NULL;
 384     }
 385     HeapRegion* new_head = head->get_next_dirty_cards_region();
 386     if (head == new_head) {
 387       // The last region.
 388       new_head = NULL;
 389     }
 390     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 391                                           head);
 392   } while (hr != head);
 393   assert(hr != NULL, "invariant");
 394   hr->set_next_dirty_cards_region(NULL);
 395   return hr;
 396 }
 397 
 398 // Returns true if the reference points to an object that
 399 // can move in an incremental collection.
 400 bool G1CollectedHeap::is_scavengable(const void* p) {
 401   HeapRegion* hr = heap_region_containing(p);
 402   return !hr->is_pinned();
 403 }
 404 
 405 // Private methods.
 406 
 407 HeapRegion*
 408 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 409   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 410   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 411     if (!_secondary_free_list.is_empty()) {
 412       if (G1ConcRegionFreeingVerbose) {
 413         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 414                                "secondary_free_list has %u entries",
 415                                _secondary_free_list.length());
 416       }
 417       // It looks as if there are free regions available on the
 418       // secondary_free_list. Let's move them to the free_list and try
 419       // again to allocate from it.
 420       append_secondary_free_list();
 421 
 422       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 423              "empty we should have moved at least one entry to the free_list");
 424       HeapRegion* res = _hrm.allocate_free_region(is_old);
 425       if (G1ConcRegionFreeingVerbose) {
 426         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 427                                "allocated " HR_FORMAT " from secondary_free_list",
 428                                HR_FORMAT_PARAMS(res));
 429       }
 430       return res;
 431     }
 432 
 433     // Wait here until we get notified either when (a) there are no
 434     // more free regions coming or (b) some regions have been moved on
 435     // the secondary_free_list.
 436     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 437   }
 438 
 439   if (G1ConcRegionFreeingVerbose) {
 440     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 441                            "could not allocate from secondary_free_list");
 442   }
 443   return NULL;
 444 }
 445 
 446 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 447   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 448          "the only time we use this to allocate a humongous region is "
 449          "when we are allocating a single humongous region");
 450 
 451   HeapRegion* res;
 452   if (G1StressConcRegionFreeing) {
 453     if (!_secondary_free_list.is_empty()) {
 454       if (G1ConcRegionFreeingVerbose) {
 455         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 456                                "forced to look at the secondary_free_list");
 457       }
 458       res = new_region_try_secondary_free_list(is_old);
 459       if (res != NULL) {
 460         return res;
 461       }
 462     }
 463   }
 464 
 465   res = _hrm.allocate_free_region(is_old);
 466 
 467   if (res == NULL) {
 468     if (G1ConcRegionFreeingVerbose) {
 469       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 470                              "res == NULL, trying the secondary_free_list");
 471     }
 472     res = new_region_try_secondary_free_list(is_old);
 473   }
 474   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 475     // Currently, only attempts to allocate GC alloc regions set
 476     // do_expand to true. So, we should only reach here during a
 477     // safepoint. If this assumption changes we might have to
 478     // reconsider the use of _expand_heap_after_alloc_failure.
 479     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 480 
 481     ergo_verbose1(ErgoHeapSizing,
 482                   "attempt heap expansion",
 483                   ergo_format_reason("region allocation request failed")
 484                   ergo_format_byte("allocation request"),
 485                   word_size * HeapWordSize);
 486     if (expand(word_size * HeapWordSize)) {
 487       // Given that expand() succeeded in expanding the heap, and we
 488       // always expand the heap by an amount aligned to the heap
 489       // region size, the free list should in theory not be empty.
 490       // In either case allocate_free_region() will check for NULL.
 491       res = _hrm.allocate_free_region(is_old);
 492     } else {
 493       _expand_heap_after_alloc_failure = false;
 494     }
 495   }
 496   return res;
 497 }
 498 
 499 HeapWord*
 500 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 501                                                            uint num_regions,
 502                                                            size_t word_size,
 503                                                            AllocationContext_t context) {
 504   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 505   assert(is_humongous(word_size), "word_size should be humongous");
 506   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 507 
 508   // Index of last region in the series + 1.
 509   uint last = first + num_regions;
 510 
 511   // We need to initialize the region(s) we just discovered. This is
 512   // a bit tricky given that it can happen concurrently with
 513   // refinement threads refining cards on these regions and
 514   // potentially wanting to refine the BOT as they are scanning
 515   // those cards (this can happen shortly after a cleanup; see CR
 516   // 6991377). So we have to set up the region(s) carefully and in
 517   // a specific order.
 518 
 519   // The word size sum of all the regions we will allocate.
 520   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 521   assert(word_size <= word_size_sum, "sanity");
 522 
 523   // This will be the "starts humongous" region.
 524   HeapRegion* first_hr = region_at(first);
 525   // The header of the new object will be placed at the bottom of
 526   // the first region.
 527   HeapWord* new_obj = first_hr->bottom();
 528   // This will be the new end of the first region in the series that
 529   // should also match the end of the last region in the series.
 530   HeapWord* new_end = new_obj + word_size_sum;
 531   // This will be the new top of the first region that will reflect
 532   // this allocation.
 533   HeapWord* new_top = new_obj + word_size;
 534 
 535   // First, we need to zero the header of the space that we will be
 536   // allocating. When we update top further down, some refinement
 537   // threads might try to scan the region. By zeroing the header we
 538   // ensure that any thread that will try to scan the region will
 539   // come across the zero klass word and bail out.
 540   //
 541   // NOTE: It would not have been correct to have used
 542   // CollectedHeap::fill_with_object() and make the space look like
 543   // an int array. The thread that is doing the allocation will
 544   // later update the object header to a potentially different array
 545   // type and, for a very short period of time, the klass and length
 546   // fields will be inconsistent. This could cause a refinement
 547   // thread to calculate the object size incorrectly.
 548   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 549 
 550   // We will set up the first region as "starts humongous". This
 551   // will also update the BOT covering all the regions to reflect
 552   // that there is a single object that starts at the bottom of the
 553   // first region.
 554   first_hr->set_starts_humongous(new_top, new_end);
 555   first_hr->set_allocation_context(context);
 556   // Then, if there are any, we will set up the "continues
 557   // humongous" regions.
 558   HeapRegion* hr = NULL;
 559   for (uint i = first + 1; i < last; ++i) {
 560     hr = region_at(i);
 561     hr->set_continues_humongous(first_hr);
 562     hr->set_allocation_context(context);
 563   }
 564   // If we have "continues humongous" regions (hr != NULL), then the
 565   // end of the last one should match new_end.
 566   assert(hr == NULL || hr->end() == new_end, "sanity");
 567 
 568   // Up to this point no concurrent thread would have been able to
 569   // do any scanning on any region in this series. All the top
 570   // fields still point to bottom, so the intersection between
 571   // [bottom,top] and [card_start,card_end] will be empty. Before we
 572   // update the top fields, we'll do a storestore to make sure that
 573   // no thread sees the update to top before the zeroing of the
 574   // object header and the BOT initialization.
 575   OrderAccess::storestore();
 576 
 577   // Now that the BOT and the object header have been initialized,
 578   // we can update top of the "starts humongous" region.
 579   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 580          "new_top should be in this region");
 581   first_hr->set_top(new_top);
 582   if (_hr_printer.is_active()) {
 583     HeapWord* bottom = first_hr->bottom();
 584     HeapWord* end = first_hr->orig_end();
 585     if ((first + 1) == last) {
 586       // the series has a single humongous region
 587       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 588     } else {
 589       // the series has more than one humongous regions
 590       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 591     }
 592   }
 593 
 594   // Now, we will update the top fields of the "continues humongous"
 595   // regions. The reason we need to do this is that, otherwise,
 596   // these regions would look empty and this will confuse parts of
 597   // G1. For example, the code that looks for a consecutive number
 598   // of empty regions will consider them empty and try to
 599   // re-allocate them. We can extend is_empty() to also include
 600   // !is_continues_humongous(), but it is easier to just update the top
 601   // fields here. The way we set top for all regions (i.e., top ==
 602   // end for all regions but the last one, top == new_top for the
 603   // last one) is actually used when we will free up the humongous
 604   // region in free_humongous_region().
 605   hr = NULL;
 606   for (uint i = first + 1; i < last; ++i) {
 607     hr = region_at(i);
 608     if ((i + 1) == last) {
 609       // last continues humongous region
 610       assert(hr->bottom() < new_top && new_top <= hr->end(),
 611              "new_top should fall on this region");
 612       hr->set_top(new_top);
 613       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 614     } else {
 615       // not last one
 616       assert(new_top > hr->end(), "new_top should be above this region");
 617       hr->set_top(hr->end());
 618       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 619     }
 620   }
 621   // If we have continues humongous regions (hr != NULL), then the
 622   // end of the last one should match new_end and its top should
 623   // match new_top.
 624   assert(hr == NULL ||
 625          (hr->end() == new_end && hr->top() == new_top), "sanity");
 626   check_bitmaps("Humongous Region Allocation", first_hr);
 627 
 628   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 629   increase_used(first_hr->used());
 630   _humongous_set.add(first_hr);
 631 
 632   return new_obj;
 633 }
 634 
 635 // If could fit into free regions w/o expansion, try.
 636 // Otherwise, if can expand, do so.
 637 // Otherwise, if using ex regions might help, try with ex given back.
 638 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 639   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 640 
 641   verify_region_sets_optional();
 642 
 643   uint first = G1_NO_HRM_INDEX;
 644   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 645 
 646   if (obj_regions == 1) {
 647     // Only one region to allocate, try to use a fast path by directly allocating
 648     // from the free lists. Do not try to expand here, we will potentially do that
 649     // later.
 650     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 651     if (hr != NULL) {
 652       first = hr->hrm_index();
 653     }
 654   } else {
 655     // We can't allocate humongous regions spanning more than one region while
 656     // cleanupComplete() is running, since some of the regions we find to be
 657     // empty might not yet be added to the free list. It is not straightforward
 658     // to know in which list they are on so that we can remove them. We only
 659     // need to do this if we need to allocate more than one region to satisfy the
 660     // current humongous allocation request. If we are only allocating one region
 661     // we use the one-region region allocation code (see above), that already
 662     // potentially waits for regions from the secondary free list.
 663     wait_while_free_regions_coming();
 664     append_secondary_free_list_if_not_empty_with_lock();
 665 
 666     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 667     // are lucky enough to find some.
 668     first = _hrm.find_contiguous_only_empty(obj_regions);
 669     if (first != G1_NO_HRM_INDEX) {
 670       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 671     }
 672   }
 673 
 674   if (first == G1_NO_HRM_INDEX) {
 675     // Policy: We could not find enough regions for the humongous object in the
 676     // free list. Look through the heap to find a mix of free and uncommitted regions.
 677     // If so, try expansion.
 678     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 679     if (first != G1_NO_HRM_INDEX) {
 680       // We found something. Make sure these regions are committed, i.e. expand
 681       // the heap. Alternatively we could do a defragmentation GC.
 682       ergo_verbose1(ErgoHeapSizing,
 683                     "attempt heap expansion",
 684                     ergo_format_reason("humongous allocation request failed")
 685                     ergo_format_byte("allocation request"),
 686                     word_size * HeapWordSize);
 687 
 688       _hrm.expand_at(first, obj_regions);
 689       g1_policy()->record_new_heap_size(num_regions());
 690 
 691 #ifdef ASSERT
 692       for (uint i = first; i < first + obj_regions; ++i) {
 693         HeapRegion* hr = region_at(i);
 694         assert(hr->is_free(), "sanity");
 695         assert(hr->is_empty(), "sanity");
 696         assert(is_on_master_free_list(hr), "sanity");
 697       }
 698 #endif
 699       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 700     } else {
 701       // Policy: Potentially trigger a defragmentation GC.
 702     }
 703   }
 704 
 705   HeapWord* result = NULL;
 706   if (first != G1_NO_HRM_INDEX) {
 707     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 708                                                        word_size, context);
 709     assert(result != NULL, "it should always return a valid result");
 710 
 711     // A successful humongous object allocation changes the used space
 712     // information of the old generation so we need to recalculate the
 713     // sizes and update the jstat counters here.
 714     g1mm()->update_sizes();
 715   }
 716 
 717   verify_region_sets_optional();
 718 
 719   return result;
 720 }
 721 
 722 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 723   assert_heap_not_locked_and_not_at_safepoint();
 724   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 725 
 726   uint dummy_gc_count_before;
 727   uint dummy_gclocker_retry_count = 0;
 728   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 729 }
 730 
 731 HeapWord*
 732 G1CollectedHeap::mem_allocate(size_t word_size,
 733                               bool*  gc_overhead_limit_was_exceeded) {
 734   assert_heap_not_locked_and_not_at_safepoint();
 735 
 736   // Loop until the allocation is satisfied, or unsatisfied after GC.
 737   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 738     uint gc_count_before;
 739 
 740     HeapWord* result = NULL;
 741     if (!is_humongous(word_size)) {
 742       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 743     } else {
 744       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 745     }
 746     if (result != NULL) {
 747       return result;
 748     }
 749 
 750     // Create the garbage collection operation...
 751     VM_G1CollectForAllocation op(gc_count_before, word_size);
 752     op.set_allocation_context(AllocationContext::current());
 753 
 754     // ...and get the VM thread to execute it.
 755     VMThread::execute(&op);
 756 
 757     if (op.prologue_succeeded() && op.pause_succeeded()) {
 758       // If the operation was successful we'll return the result even
 759       // if it is NULL. If the allocation attempt failed immediately
 760       // after a Full GC, it's unlikely we'll be able to allocate now.
 761       HeapWord* result = op.result();
 762       if (result != NULL && !is_humongous(word_size)) {
 763         // Allocations that take place on VM operations do not do any
 764         // card dirtying and we have to do it here. We only have to do
 765         // this for non-humongous allocations, though.
 766         dirty_young_block(result, word_size);
 767       }
 768       return result;
 769     } else {
 770       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 771         return NULL;
 772       }
 773       assert(op.result() == NULL,
 774              "the result should be NULL if the VM op did not succeed");
 775     }
 776 
 777     // Give a warning if we seem to be looping forever.
 778     if ((QueuedAllocationWarningCount > 0) &&
 779         (try_count % QueuedAllocationWarningCount == 0)) {
 780       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 781     }
 782   }
 783 
 784   ShouldNotReachHere();
 785   return NULL;
 786 }
 787 
 788 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 789                                                    AllocationContext_t context,
 790                                                    uint* gc_count_before_ret,
 791                                                    uint* gclocker_retry_count_ret) {
 792   // Make sure you read the note in attempt_allocation_humongous().
 793 
 794   assert_heap_not_locked_and_not_at_safepoint();
 795   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 796          "be called for humongous allocation requests");
 797 
 798   // We should only get here after the first-level allocation attempt
 799   // (attempt_allocation()) failed to allocate.
 800 
 801   // We will loop until a) we manage to successfully perform the
 802   // allocation or b) we successfully schedule a collection which
 803   // fails to perform the allocation. b) is the only case when we'll
 804   // return NULL.
 805   HeapWord* result = NULL;
 806   for (int try_count = 1; /* we'll return */; try_count += 1) {
 807     bool should_try_gc;
 808     uint gc_count_before;
 809 
 810     {
 811       MutexLockerEx x(Heap_lock);
 812       result = _allocator->attempt_allocation_locked(word_size, context);
 813       if (result != NULL) {
 814         return result;
 815       }
 816 
 817       if (GC_locker::is_active_and_needs_gc()) {
 818         if (g1_policy()->can_expand_young_list()) {
 819           // No need for an ergo verbose message here,
 820           // can_expand_young_list() does this when it returns true.
 821           result = _allocator->attempt_allocation_force(word_size, context);
 822           if (result != NULL) {
 823             return result;
 824           }
 825         }
 826         should_try_gc = false;
 827       } else {
 828         // The GCLocker may not be active but the GCLocker initiated
 829         // GC may not yet have been performed (GCLocker::needs_gc()
 830         // returns true). In this case we do not try this GC and
 831         // wait until the GCLocker initiated GC is performed, and
 832         // then retry the allocation.
 833         if (GC_locker::needs_gc()) {
 834           should_try_gc = false;
 835         } else {
 836           // Read the GC count while still holding the Heap_lock.
 837           gc_count_before = total_collections();
 838           should_try_gc = true;
 839         }
 840       }
 841     }
 842 
 843     if (should_try_gc) {
 844       bool succeeded;
 845       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 846                                    GCCause::_g1_inc_collection_pause);
 847       if (result != NULL) {
 848         assert(succeeded, "only way to get back a non-NULL result");
 849         return result;
 850       }
 851 
 852       if (succeeded) {
 853         // If we get here we successfully scheduled a collection which
 854         // failed to allocate. No point in trying to allocate
 855         // further. We'll just return NULL.
 856         MutexLockerEx x(Heap_lock);
 857         *gc_count_before_ret = total_collections();
 858         return NULL;
 859       }
 860     } else {
 861       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 862         MutexLockerEx x(Heap_lock);
 863         *gc_count_before_ret = total_collections();
 864         return NULL;
 865       }
 866       // The GCLocker is either active or the GCLocker initiated
 867       // GC has not yet been performed. Stall until it is and
 868       // then retry the allocation.
 869       GC_locker::stall_until_clear();
 870       (*gclocker_retry_count_ret) += 1;
 871     }
 872 
 873     // We can reach here if we were unsuccessful in scheduling a
 874     // collection (because another thread beat us to it) or if we were
 875     // stalled due to the GC locker. In either can we should retry the
 876     // allocation attempt in case another thread successfully
 877     // performed a collection and reclaimed enough space. We do the
 878     // first attempt (without holding the Heap_lock) here and the
 879     // follow-on attempt will be at the start of the next loop
 880     // iteration (after taking the Heap_lock).
 881     result = _allocator->attempt_allocation(word_size, context);
 882     if (result != NULL) {
 883       return result;
 884     }
 885 
 886     // Give a warning if we seem to be looping forever.
 887     if ((QueuedAllocationWarningCount > 0) &&
 888         (try_count % QueuedAllocationWarningCount == 0)) {
 889       warning("G1CollectedHeap::attempt_allocation_slow() "
 890               "retries %d times", try_count);
 891     }
 892   }
 893 
 894   ShouldNotReachHere();
 895   return NULL;
 896 }
 897 
 898 void G1CollectedHeap::begin_archive_alloc_range() {
 899   assert_at_safepoint(true /* should_be_vm_thread */);
 900   if (_archive_allocator == NULL) {
 901     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 902   }
 903 }
 904 
 905 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 906   // Allocations in archive regions cannot be of a size that would be considered
 907   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 908   // may be different at archive-restore time.
 909   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 910 }
 911 
 912 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 913   assert_at_safepoint(true /* should_be_vm_thread */);
 914   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 915   if (is_archive_alloc_too_large(word_size)) {
 916     return NULL;
 917   }
 918   return _archive_allocator->archive_mem_allocate(word_size);
 919 }
 920 
 921 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 922                                               size_t end_alignment_in_bytes) {
 923   assert_at_safepoint(true /* should_be_vm_thread */);
 924   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 925 
 926   // Call complete_archive to do the real work, filling in the MemRegion
 927   // array with the archive regions.
 928   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 929   delete _archive_allocator;
 930   _archive_allocator = NULL;
 931 }
 932 
 933 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 934   assert(ranges != NULL, "MemRegion array NULL");
 935   assert(count != 0, "No MemRegions provided");
 936   MemRegion reserved = _hrm.reserved();
 937   for (size_t i = 0; i < count; i++) {
 938     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 939       return false;
 940     }
 941   }
 942   return true;
 943 }
 944 
 945 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 946   assert(!is_init_completed(), "Expect to be called at JVM init time");
 947   assert(ranges != NULL, "MemRegion array NULL");
 948   assert(count != 0, "No MemRegions provided");
 949   MutexLockerEx x(Heap_lock);
 950 
 951   MemRegion reserved = _hrm.reserved();
 952   HeapWord* prev_last_addr = NULL;
 953   HeapRegion* prev_last_region = NULL;
 954 
 955   // Temporarily disable pretouching of heap pages. This interface is used
 956   // when mmap'ing archived heap data in, so pre-touching is wasted.
 957   FlagSetting fs(AlwaysPreTouch, false);
 958 
 959   // Enable archive object checking in G1MarkSweep. We have to let it know
 960   // about each archive range, so that objects in those ranges aren't marked.
 961   G1MarkSweep::enable_archive_object_check();
 962 
 963   // For each specified MemRegion range, allocate the corresponding G1
 964   // regions and mark them as archive regions. We expect the ranges in
 965   // ascending starting address order, without overlap.
 966   for (size_t i = 0; i < count; i++) {
 967     MemRegion curr_range = ranges[i];
 968     HeapWord* start_address = curr_range.start();
 969     size_t word_size = curr_range.word_size();
 970     HeapWord* last_address = curr_range.last();
 971     size_t commits = 0;
 972 
 973     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 974               err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 975               p2i(start_address), p2i(last_address)));
 976     guarantee(start_address > prev_last_addr,
 977               err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 978               p2i(start_address), p2i(prev_last_addr)));
 979     prev_last_addr = last_address;
 980 
 981     // Check for ranges that start in the same G1 region in which the previous
 982     // range ended, and adjust the start address so we don't try to allocate
 983     // the same region again. If the current range is entirely within that
 984     // region, skip it, just adjusting the recorded top.
 985     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 986     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 987       start_address = start_region->end();
 988       if (start_address > last_address) {
 989         increase_used(word_size * HeapWordSize);
 990         start_region->set_top(last_address + 1);
 991         continue;
 992       }
 993       start_region->set_top(start_address);
 994       curr_range = MemRegion(start_address, last_address + 1);
 995       start_region = _hrm.addr_to_region(start_address);
 996     }
 997 
 998     // Perform the actual region allocation, exiting if it fails.
 999     // Then note how much new space we have allocated.
1000     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1001       return false;
1002     }
1003     increase_used(word_size * HeapWordSize);
1004     if (commits != 0) {
1005       ergo_verbose1(ErgoHeapSizing,
1006                     "attempt heap expansion",
1007                     ergo_format_reason("allocate archive regions")
1008                     ergo_format_byte("total size"),
1009                     HeapRegion::GrainWords * HeapWordSize * commits);
1010     }
1011 
1012     // Mark each G1 region touched by the range as archive, add it to the old set,
1013     // and set the allocation context and top.
1014     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1015     HeapRegion* last_region = _hrm.addr_to_region(last_address);
1016     prev_last_region = last_region;
1017 
1018     while (curr_region != NULL) {
1019       assert(curr_region->is_empty() && !curr_region->is_pinned(),
1020              err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1021       _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1022       curr_region->set_allocation_context(AllocationContext::system());
1023       curr_region->set_archive();
1024       _old_set.add(curr_region);
1025       if (curr_region != last_region) {
1026         curr_region->set_top(curr_region->end());
1027         curr_region = _hrm.next_region_in_heap(curr_region);
1028       } else {
1029         curr_region->set_top(last_address + 1);
1030         curr_region = NULL;
1031       }
1032     }
1033 
1034     // Notify mark-sweep of the archive range.
1035     G1MarkSweep::set_range_archive(curr_range, true);
1036   }
1037   return true;
1038 }
1039 
1040 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1041   assert(!is_init_completed(), "Expect to be called at JVM init time");
1042   assert(ranges != NULL, "MemRegion array NULL");
1043   assert(count != 0, "No MemRegions provided");
1044   MemRegion reserved = _hrm.reserved();
1045   HeapWord *prev_last_addr = NULL;
1046   HeapRegion* prev_last_region = NULL;
1047 
1048   // For each MemRegion, create filler objects, if needed, in the G1 regions
1049   // that contain the address range. The address range actually within the
1050   // MemRegion will not be modified. That is assumed to have been initialized
1051   // elsewhere, probably via an mmap of archived heap data.
1052   MutexLockerEx x(Heap_lock);
1053   for (size_t i = 0; i < count; i++) {
1054     HeapWord* start_address = ranges[i].start();
1055     HeapWord* last_address = ranges[i].last();
1056 
1057     assert(reserved.contains(start_address) && reserved.contains(last_address),
1058            err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1059                    p2i(start_address), p2i(last_address)));
1060     assert(start_address > prev_last_addr,
1061            err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1062                    p2i(start_address), p2i(prev_last_addr)));
1063 
1064     HeapRegion* start_region = _hrm.addr_to_region(start_address);
1065     HeapRegion* last_region = _hrm.addr_to_region(last_address);
1066     HeapWord* bottom_address = start_region->bottom();
1067 
1068     // Check for a range beginning in the same region in which the
1069     // previous one ended.
1070     if (start_region == prev_last_region) {
1071       bottom_address = prev_last_addr + 1;
1072     }
1073 
1074     // Verify that the regions were all marked as archive regions by
1075     // alloc_archive_regions.
1076     HeapRegion* curr_region = start_region;
1077     while (curr_region != NULL) {
1078       guarantee(curr_region->is_archive(),
1079                 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1080       if (curr_region != last_region) {
1081         curr_region = _hrm.next_region_in_heap(curr_region);
1082       } else {
1083         curr_region = NULL;
1084       }
1085     }
1086 
1087     prev_last_addr = last_address;
1088     prev_last_region = last_region;
1089 
1090     // Fill the memory below the allocated range with dummy object(s),
1091     // if the region bottom does not match the range start, or if the previous
1092     // range ended within the same G1 region, and there is a gap.
1093     if (start_address != bottom_address) {
1094       size_t fill_size = pointer_delta(start_address, bottom_address);
1095       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1096       increase_used(fill_size * HeapWordSize);
1097     }
1098   }
1099 }
1100 
1101 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1102                                                      uint* gc_count_before_ret,
1103                                                      uint* gclocker_retry_count_ret) {
1104   assert_heap_not_locked_and_not_at_safepoint();
1105   assert(!is_humongous(word_size), "attempt_allocation() should not "
1106          "be called for humongous allocation requests");
1107 
1108   AllocationContext_t context = AllocationContext::current();
1109   HeapWord* result = _allocator->attempt_allocation(word_size, context);
1110 
1111   if (result == NULL) {
1112     result = attempt_allocation_slow(word_size,
1113                                      context,
1114                                      gc_count_before_ret,
1115                                      gclocker_retry_count_ret);
1116   }
1117   assert_heap_not_locked();
1118   if (result != NULL) {
1119     dirty_young_block(result, word_size);
1120   }
1121   return result;
1122 }
1123 
1124 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
1125   assert(!is_init_completed(), "Expect to be called at JVM init time");
1126   assert(ranges != NULL, "MemRegion array NULL");
1127   assert(count != 0, "No MemRegions provided");
1128   MemRegion reserved = _hrm.reserved();
1129   HeapWord* prev_last_addr = NULL;
1130   HeapRegion* prev_last_region = NULL;
1131   size_t size_used = 0;
1132   size_t uncommitted_regions = 0;
1133 
1134   // For each Memregion, free the G1 regions that constitute it, and
1135   // notify mark-sweep that the range is no longer to be considered 'archive.'
1136   MutexLockerEx x(Heap_lock);
1137   for (size_t i = 0; i < count; i++) {
1138     HeapWord* start_address = ranges[i].start();
1139     HeapWord* last_address = ranges[i].last();
1140 
1141     assert(reserved.contains(start_address) && reserved.contains(last_address),
1142            err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1143                    p2i(start_address), p2i(last_address)));
1144     assert(start_address > prev_last_addr,
1145            err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1146                    p2i(start_address), p2i(prev_last_addr)));
1147     size_used += ranges[i].byte_size();
1148     prev_last_addr = last_address;
1149 
1150     HeapRegion* start_region = _hrm.addr_to_region(start_address);
1151     HeapRegion* last_region = _hrm.addr_to_region(last_address);
1152 
1153     // Check for ranges that start in the same G1 region in which the previous
1154     // range ended, and adjust the start address so we don't try to free
1155     // the same region again. If the current range is entirely within that
1156     // region, skip it.
1157     if (start_region == prev_last_region) {
1158       start_address = start_region->end();
1159       if (start_address > last_address) {
1160         continue;
1161       }
1162       start_region = _hrm.addr_to_region(start_address);
1163     }
1164     prev_last_region = last_region;
1165 
1166     // After verifying that each region was marked as an archive region by
1167     // alloc_archive_regions, set it free and empty and uncommit it.
1168     HeapRegion* curr_region = start_region;
1169     while (curr_region != NULL) {
1170       guarantee(curr_region->is_archive(),
1171                 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1172       uint curr_index = curr_region->hrm_index();
1173       _old_set.remove(curr_region);
1174       curr_region->set_free();
1175       curr_region->set_top(curr_region->bottom());
1176       if (curr_region != last_region) {
1177         curr_region = _hrm.next_region_in_heap(curr_region);
1178       } else {
1179         curr_region = NULL;
1180       }
1181       _hrm.shrink_at(curr_index, 1);
1182       uncommitted_regions++;
1183     }
1184 
1185     // Notify mark-sweep that this is no longer an archive range.
1186     G1MarkSweep::set_range_archive(ranges[i], false);
1187   }
1188 
1189   if (uncommitted_regions != 0) {
1190     ergo_verbose1(ErgoHeapSizing,
1191                   "attempt heap shrinking",
1192                   ergo_format_reason("uncommitted archive regions")
1193                   ergo_format_byte("total size"),
1194                   HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1195   }
1196   decrease_used(size_used);
1197 }
1198 
1199 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1200                                                         uint* gc_count_before_ret,
1201                                                         uint* gclocker_retry_count_ret) {
1202   // The structure of this method has a lot of similarities to
1203   // attempt_allocation_slow(). The reason these two were not merged
1204   // into a single one is that such a method would require several "if
1205   // allocation is not humongous do this, otherwise do that"
1206   // conditional paths which would obscure its flow. In fact, an early
1207   // version of this code did use a unified method which was harder to
1208   // follow and, as a result, it had subtle bugs that were hard to
1209   // track down. So keeping these two methods separate allows each to
1210   // be more readable. It will be good to keep these two in sync as
1211   // much as possible.
1212 
1213   assert_heap_not_locked_and_not_at_safepoint();
1214   assert(is_humongous(word_size), "attempt_allocation_humongous() "
1215          "should only be called for humongous allocations");
1216 
1217   // Humongous objects can exhaust the heap quickly, so we should check if we
1218   // need to start a marking cycle at each humongous object allocation. We do
1219   // the check before we do the actual allocation. The reason for doing it
1220   // before the allocation is that we avoid having to keep track of the newly
1221   // allocated memory while we do a GC.
1222   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1223                                            word_size)) {
1224     collect(GCCause::_g1_humongous_allocation);
1225   }
1226 
1227   // We will loop until a) we manage to successfully perform the
1228   // allocation or b) we successfully schedule a collection which
1229   // fails to perform the allocation. b) is the only case when we'll
1230   // return NULL.
1231   HeapWord* result = NULL;
1232   for (int try_count = 1; /* we'll return */; try_count += 1) {
1233     bool should_try_gc;
1234     uint gc_count_before;
1235 
1236     {
1237       MutexLockerEx x(Heap_lock);
1238 
1239       // Given that humongous objects are not allocated in young
1240       // regions, we'll first try to do the allocation without doing a
1241       // collection hoping that there's enough space in the heap.
1242       result = humongous_obj_allocate(word_size, AllocationContext::current());
1243       if (result != NULL) {
1244         return result;
1245       }
1246 
1247       if (GC_locker::is_active_and_needs_gc()) {
1248         should_try_gc = false;
1249       } else {
1250          // The GCLocker may not be active but the GCLocker initiated
1251         // GC may not yet have been performed (GCLocker::needs_gc()
1252         // returns true). In this case we do not try this GC and
1253         // wait until the GCLocker initiated GC is performed, and
1254         // then retry the allocation.
1255         if (GC_locker::needs_gc()) {
1256           should_try_gc = false;
1257         } else {
1258           // Read the GC count while still holding the Heap_lock.
1259           gc_count_before = total_collections();
1260           should_try_gc = true;
1261         }
1262       }
1263     }
1264 
1265     if (should_try_gc) {
1266       // If we failed to allocate the humongous object, we should try to
1267       // do a collection pause (if we're allowed) in case it reclaims
1268       // enough space for the allocation to succeed after the pause.
1269 
1270       bool succeeded;
1271       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1272                                    GCCause::_g1_humongous_allocation);
1273       if (result != NULL) {
1274         assert(succeeded, "only way to get back a non-NULL result");
1275         return result;
1276       }
1277 
1278       if (succeeded) {
1279         // If we get here we successfully scheduled a collection which
1280         // failed to allocate. No point in trying to allocate
1281         // further. We'll just return NULL.
1282         MutexLockerEx x(Heap_lock);
1283         *gc_count_before_ret = total_collections();
1284         return NULL;
1285       }
1286     } else {
1287       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1288         MutexLockerEx x(Heap_lock);
1289         *gc_count_before_ret = total_collections();
1290         return NULL;
1291       }
1292       // The GCLocker is either active or the GCLocker initiated
1293       // GC has not yet been performed. Stall until it is and
1294       // then retry the allocation.
1295       GC_locker::stall_until_clear();
1296       (*gclocker_retry_count_ret) += 1;
1297     }
1298 
1299     // We can reach here if we were unsuccessful in scheduling a
1300     // collection (because another thread beat us to it) or if we were
1301     // stalled due to the GC locker. In either can we should retry the
1302     // allocation attempt in case another thread successfully
1303     // performed a collection and reclaimed enough space.  Give a
1304     // warning if we seem to be looping forever.
1305 
1306     if ((QueuedAllocationWarningCount > 0) &&
1307         (try_count % QueuedAllocationWarningCount == 0)) {
1308       warning("G1CollectedHeap::attempt_allocation_humongous() "
1309               "retries %d times", try_count);
1310     }
1311   }
1312 
1313   ShouldNotReachHere();
1314   return NULL;
1315 }
1316 
1317 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1318                                                            AllocationContext_t context,
1319                                                            bool expect_null_mutator_alloc_region) {
1320   assert_at_safepoint(true /* should_be_vm_thread */);
1321   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1322          "the current alloc region was unexpectedly found to be non-NULL");
1323 
1324   if (!is_humongous(word_size)) {
1325     return _allocator->attempt_allocation_locked(word_size, context);
1326   } else {
1327     HeapWord* result = humongous_obj_allocate(word_size, context);
1328     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1329       collector_state()->set_initiate_conc_mark_if_possible(true);
1330     }
1331     return result;
1332   }
1333 
1334   ShouldNotReachHere();
1335 }
1336 
1337 class PostMCRemSetClearClosure: public HeapRegionClosure {
1338   G1CollectedHeap* _g1h;
1339   ModRefBarrierSet* _mr_bs;
1340 public:
1341   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1342     _g1h(g1h), _mr_bs(mr_bs) {}
1343 
1344   bool doHeapRegion(HeapRegion* r) {
1345     HeapRegionRemSet* hrrs = r->rem_set();
1346 
1347     if (r->is_continues_humongous()) {
1348       // We'll assert that the strong code root list and RSet is empty
1349       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1350       assert(hrrs->occupied() == 0, "RSet should be empty");
1351       return false;
1352     }
1353 
1354     _g1h->reset_gc_time_stamps(r);
1355     hrrs->clear();
1356     // You might think here that we could clear just the cards
1357     // corresponding to the used region.  But no: if we leave a dirty card
1358     // in a region we might allocate into, then it would prevent that card
1359     // from being enqueued, and cause it to be missed.
1360     // Re: the performance cost: we shouldn't be doing full GC anyway!
1361     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1362 
1363     return false;
1364   }
1365 };
1366 
1367 void G1CollectedHeap::clear_rsets_post_compaction() {
1368   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1369   heap_region_iterate(&rs_clear);
1370 }
1371 
1372 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1373   G1CollectedHeap*   _g1h;
1374   UpdateRSOopClosure _cl;
1375 public:
1376   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1377     _cl(g1->g1_rem_set(), worker_i),
1378     _g1h(g1)
1379   { }
1380 
1381   bool doHeapRegion(HeapRegion* r) {
1382     if (!r->is_continues_humongous()) {
1383       _cl.set_from(r);
1384       r->oop_iterate(&_cl);
1385     }
1386     return false;
1387   }
1388 };
1389 
1390 class ParRebuildRSTask: public AbstractGangTask {
1391   G1CollectedHeap* _g1;
1392   HeapRegionClaimer _hrclaimer;
1393 
1394 public:
1395   ParRebuildRSTask(G1CollectedHeap* g1) :
1396       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1397 
1398   void work(uint worker_id) {
1399     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1400     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1401   }
1402 };
1403 
1404 class PostCompactionPrinterClosure: public HeapRegionClosure {
1405 private:
1406   G1HRPrinter* _hr_printer;
1407 public:
1408   bool doHeapRegion(HeapRegion* hr) {
1409     assert(!hr->is_young(), "not expecting to find young regions");
1410     if (hr->is_free()) {
1411       // We only generate output for non-empty regions.
1412     } else if (hr->is_starts_humongous()) {
1413       if (hr->region_num() == 1) {
1414         // single humongous region
1415         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1416       } else {
1417         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1418       }
1419     } else if (hr->is_continues_humongous()) {
1420       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1421     } else if (hr->is_archive()) {
1422       _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1423     } else if (hr->is_old()) {
1424       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1425     } else {
1426       ShouldNotReachHere();
1427     }
1428     return false;
1429   }
1430 
1431   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1432     : _hr_printer(hr_printer) { }
1433 };
1434 
1435 void G1CollectedHeap::print_hrm_post_compaction() {
1436   PostCompactionPrinterClosure cl(hr_printer());
1437   heap_region_iterate(&cl);
1438 }
1439 
1440 bool G1CollectedHeap::do_collection(bool explicit_gc,
1441                                     bool clear_all_soft_refs,
1442                                     size_t word_size) {
1443   assert_at_safepoint(true /* should_be_vm_thread */);
1444 
1445   if (GC_locker::check_active_before_gc()) {
1446     return false;
1447   }
1448 
1449   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1450   gc_timer->register_gc_start();
1451 
1452   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1453   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1454 
1455   SvcGCMarker sgcm(SvcGCMarker::FULL);
1456   ResourceMark rm;
1457 
1458   G1Log::update_level();
1459   print_heap_before_gc();
1460   trace_heap_before_gc(gc_tracer);
1461 
1462   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1463 
1464   verify_region_sets_optional();
1465 
1466   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1467                            collector_policy()->should_clear_all_soft_refs();
1468 
1469   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1470 
1471   {
1472     IsGCActiveMark x;
1473 
1474     // Timing
1475     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1476     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1477 
1478     {
1479       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1480       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1481       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1482 
1483       g1_policy()->record_full_collection_start();
1484 
1485       // Note: When we have a more flexible GC logging framework that
1486       // allows us to add optional attributes to a GC log record we
1487       // could consider timing and reporting how long we wait in the
1488       // following two methods.
1489       wait_while_free_regions_coming();
1490       // If we start the compaction before the CM threads finish
1491       // scanning the root regions we might trip them over as we'll
1492       // be moving objects / updating references. So let's wait until
1493       // they are done. By telling them to abort, they should complete
1494       // early.
1495       _cm->root_regions()->abort();
1496       _cm->root_regions()->wait_until_scan_finished();
1497       append_secondary_free_list_if_not_empty_with_lock();
1498 
1499       gc_prologue(true);
1500       increment_total_collections(true /* full gc */);
1501       increment_old_marking_cycles_started();
1502 
1503       assert(used() == recalculate_used(), "Should be equal");
1504 
1505       verify_before_gc();
1506 
1507       check_bitmaps("Full GC Start");
1508       pre_full_gc_dump(gc_timer);
1509 
1510 #if defined(COMPILER2) || INCLUDE_JVMCI
1511       DerivedPointerTable::clear();
1512 #endif
1513 
1514       // Disable discovery and empty the discovered lists
1515       // for the CM ref processor.
1516       ref_processor_cm()->disable_discovery();
1517       ref_processor_cm()->abandon_partial_discovery();
1518       ref_processor_cm()->verify_no_references_recorded();
1519 
1520       // Abandon current iterations of concurrent marking and concurrent
1521       // refinement, if any are in progress. We have to do this before
1522       // wait_until_scan_finished() below.
1523       concurrent_mark()->abort();
1524 
1525       // Make sure we'll choose a new allocation region afterwards.
1526       _allocator->release_mutator_alloc_region();
1527       _allocator->abandon_gc_alloc_regions();
1528       g1_rem_set()->cleanupHRRS();
1529 
1530       // We should call this after we retire any currently active alloc
1531       // regions so that all the ALLOC / RETIRE events are generated
1532       // before the start GC event.
1533       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1534 
1535       // We may have added regions to the current incremental collection
1536       // set between the last GC or pause and now. We need to clear the
1537       // incremental collection set and then start rebuilding it afresh
1538       // after this full GC.
1539       abandon_collection_set(g1_policy()->inc_cset_head());
1540       g1_policy()->clear_incremental_cset();
1541       g1_policy()->stop_incremental_cset_building();
1542 
1543       tear_down_region_sets(false /* free_list_only */);
1544       collector_state()->set_gcs_are_young(true);
1545 
1546       // See the comments in g1CollectedHeap.hpp and
1547       // G1CollectedHeap::ref_processing_init() about
1548       // how reference processing currently works in G1.
1549 
1550       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1551       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1552 
1553       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1554       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1555 
1556       ref_processor_stw()->enable_discovery();
1557       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1558 
1559       // Do collection work
1560       {
1561         HandleMark hm;  // Discard invalid handles created during gc
1562         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1563       }
1564 
1565       assert(num_free_regions() == 0, "we should not have added any free regions");
1566       rebuild_region_sets(false /* free_list_only */);
1567 
1568       // Enqueue any discovered reference objects that have
1569       // not been removed from the discovered lists.
1570       ref_processor_stw()->enqueue_discovered_references();
1571 
1572 #if defined(COMPILER2) || INCLUDE_JVMCI
1573       DerivedPointerTable::update_pointers();
1574 #endif
1575 
1576       MemoryService::track_memory_usage();
1577 
1578       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1579       ref_processor_stw()->verify_no_references_recorded();
1580 
1581       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1582       ClassLoaderDataGraph::purge();
1583       MetaspaceAux::verify_metrics();
1584 
1585       // Note: since we've just done a full GC, concurrent
1586       // marking is no longer active. Therefore we need not
1587       // re-enable reference discovery for the CM ref processor.
1588       // That will be done at the start of the next marking cycle.
1589       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1590       ref_processor_cm()->verify_no_references_recorded();
1591 
1592       reset_gc_time_stamp();
1593       // Since everything potentially moved, we will clear all remembered
1594       // sets, and clear all cards.  Later we will rebuild remembered
1595       // sets. We will also reset the GC time stamps of the regions.
1596       clear_rsets_post_compaction();
1597       check_gc_time_stamps();
1598 
1599       // Resize the heap if necessary.
1600       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1601 
1602       if (_hr_printer.is_active()) {
1603         // We should do this after we potentially resize the heap so
1604         // that all the COMMIT / UNCOMMIT events are generated before
1605         // the end GC event.
1606 
1607         print_hrm_post_compaction();
1608         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1609       }
1610 
1611       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1612       if (hot_card_cache->use_cache()) {
1613         hot_card_cache->reset_card_counts();
1614         hot_card_cache->reset_hot_cache();
1615       }
1616 
1617       // Rebuild remembered sets of all regions.
1618       uint n_workers =
1619         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1620                                                 workers()->active_workers(),
1621                                                 Threads::number_of_non_daemon_threads());
1622       workers()->set_active_workers(n_workers);
1623 
1624       ParRebuildRSTask rebuild_rs_task(this);
1625       workers()->run_task(&rebuild_rs_task);
1626 
1627       // Rebuild the strong code root lists for each region
1628       rebuild_strong_code_roots();
1629 
1630       if (true) { // FIXME
1631         MetaspaceGC::compute_new_size();
1632       }
1633 
1634 #ifdef TRACESPINNING
1635       ParallelTaskTerminator::print_termination_counts();
1636 #endif
1637 
1638       // Discard all rset updates
1639       JavaThread::dirty_card_queue_set().abandon_logs();
1640       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1641 
1642       _young_list->reset_sampled_info();
1643       // At this point there should be no regions in the
1644       // entire heap tagged as young.
1645       assert(check_young_list_empty(true /* check_heap */),
1646              "young list should be empty at this point");
1647 
1648       // Update the number of full collections that have been completed.
1649       increment_old_marking_cycles_completed(false /* concurrent */);
1650 
1651       _hrm.verify_optional();
1652       verify_region_sets_optional();
1653 
1654       verify_after_gc();
1655 
1656       // Clear the previous marking bitmap, if needed for bitmap verification.
1657       // Note we cannot do this when we clear the next marking bitmap in
1658       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1659       // objects marked during a full GC against the previous bitmap.
1660       // But we need to clear it before calling check_bitmaps below since
1661       // the full GC has compacted objects and updated TAMS but not updated
1662       // the prev bitmap.
1663       if (G1VerifyBitmaps) {
1664         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1665       }
1666       check_bitmaps("Full GC End");
1667 
1668       // Start a new incremental collection set for the next pause
1669       assert(g1_policy()->collection_set() == NULL, "must be");
1670       g1_policy()->start_incremental_cset_building();
1671 
1672       clear_cset_fast_test();
1673 
1674       _allocator->init_mutator_alloc_region();
1675 
1676       g1_policy()->record_full_collection_end();
1677 
1678       if (G1Log::fine()) {
1679         g1_policy()->print_heap_transition();
1680       }
1681 
1682       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1683       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1684       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1685       // before any GC notifications are raised.
1686       g1mm()->update_sizes();
1687 
1688       gc_epilogue(true);
1689     }
1690 
1691     if (G1Log::finer()) {
1692       g1_policy()->print_detailed_heap_transition(true /* full */);
1693     }
1694 
1695     print_heap_after_gc();
1696     trace_heap_after_gc(gc_tracer);
1697 
1698     post_full_gc_dump(gc_timer);
1699 
1700     gc_timer->register_gc_end();
1701     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1702   }
1703 
1704   return true;
1705 }
1706 
1707 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1708   // do_collection() will return whether it succeeded in performing
1709   // the GC. Currently, there is no facility on the
1710   // do_full_collection() API to notify the caller than the collection
1711   // did not succeed (e.g., because it was locked out by the GC
1712   // locker). So, right now, we'll ignore the return value.
1713   bool dummy = do_collection(true,                /* explicit_gc */
1714                              clear_all_soft_refs,
1715                              0                    /* word_size */);
1716 }
1717 
1718 // This code is mostly copied from TenuredGeneration.
1719 void
1720 G1CollectedHeap::
1721 resize_if_necessary_after_full_collection(size_t word_size) {
1722   // Include the current allocation, if any, and bytes that will be
1723   // pre-allocated to support collections, as "used".
1724   const size_t used_after_gc = used();
1725   const size_t capacity_after_gc = capacity();
1726   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1727 
1728   // This is enforced in arguments.cpp.
1729   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1730          "otherwise the code below doesn't make sense");
1731 
1732   // We don't have floating point command-line arguments
1733   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1734   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1735   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1736   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1737 
1738   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1739   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1740 
1741   // We have to be careful here as these two calculations can overflow
1742   // 32-bit size_t's.
1743   double used_after_gc_d = (double) used_after_gc;
1744   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1745   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1746 
1747   // Let's make sure that they are both under the max heap size, which
1748   // by default will make them fit into a size_t.
1749   double desired_capacity_upper_bound = (double) max_heap_size;
1750   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1751                                     desired_capacity_upper_bound);
1752   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1753                                     desired_capacity_upper_bound);
1754 
1755   // We can now safely turn them into size_t's.
1756   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1757   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1758 
1759   // This assert only makes sense here, before we adjust them
1760   // with respect to the min and max heap size.
1761   assert(minimum_desired_capacity <= maximum_desired_capacity,
1762          err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1763                  "maximum_desired_capacity = " SIZE_FORMAT,
1764                  minimum_desired_capacity, maximum_desired_capacity));
1765 
1766   // Should not be greater than the heap max size. No need to adjust
1767   // it with respect to the heap min size as it's a lower bound (i.e.,
1768   // we'll try to make the capacity larger than it, not smaller).
1769   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1770   // Should not be less than the heap min size. No need to adjust it
1771   // with respect to the heap max size as it's an upper bound (i.e.,
1772   // we'll try to make the capacity smaller than it, not greater).
1773   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1774 
1775   if (capacity_after_gc < minimum_desired_capacity) {
1776     // Don't expand unless it's significant
1777     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1778     ergo_verbose4(ErgoHeapSizing,
1779                   "attempt heap expansion",
1780                   ergo_format_reason("capacity lower than "
1781                                      "min desired capacity after Full GC")
1782                   ergo_format_byte("capacity")
1783                   ergo_format_byte("occupancy")
1784                   ergo_format_byte_perc("min desired capacity"),
1785                   capacity_after_gc, used_after_gc,
1786                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1787     expand(expand_bytes);
1788 
1789     // No expansion, now see if we want to shrink
1790   } else if (capacity_after_gc > maximum_desired_capacity) {
1791     // Capacity too large, compute shrinking size
1792     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1793     ergo_verbose4(ErgoHeapSizing,
1794                   "attempt heap shrinking",
1795                   ergo_format_reason("capacity higher than "
1796                                      "max desired capacity after Full GC")
1797                   ergo_format_byte("capacity")
1798                   ergo_format_byte("occupancy")
1799                   ergo_format_byte_perc("max desired capacity"),
1800                   capacity_after_gc, used_after_gc,
1801                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1802     shrink(shrink_bytes);
1803   }
1804 }
1805 
1806 
1807 HeapWord*
1808 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1809                                            AllocationContext_t context,
1810                                            bool* succeeded) {
1811   assert_at_safepoint(true /* should_be_vm_thread */);
1812 
1813   *succeeded = true;
1814   // Let's attempt the allocation first.
1815   HeapWord* result =
1816     attempt_allocation_at_safepoint(word_size,
1817                                     context,
1818                                     false /* expect_null_mutator_alloc_region */);
1819   if (result != NULL) {
1820     assert(*succeeded, "sanity");
1821     return result;
1822   }
1823 
1824   // In a G1 heap, we're supposed to keep allocation from failing by
1825   // incremental pauses.  Therefore, at least for now, we'll favor
1826   // expansion over collection.  (This might change in the future if we can
1827   // do something smarter than full collection to satisfy a failed alloc.)
1828   result = expand_and_allocate(word_size, context);
1829   if (result != NULL) {
1830     assert(*succeeded, "sanity");
1831     return result;
1832   }
1833 
1834   // Expansion didn't work, we'll try to do a Full GC.
1835   bool gc_succeeded = do_collection(false, /* explicit_gc */
1836                                     false, /* clear_all_soft_refs */
1837                                     word_size);
1838   if (!gc_succeeded) {
1839     *succeeded = false;
1840     return NULL;
1841   }
1842 
1843   // Retry the allocation
1844   result = attempt_allocation_at_safepoint(word_size,
1845                                            context,
1846                                            true /* expect_null_mutator_alloc_region */);
1847   if (result != NULL) {
1848     assert(*succeeded, "sanity");
1849     return result;
1850   }
1851 
1852   // Then, try a Full GC that will collect all soft references.
1853   gc_succeeded = do_collection(false, /* explicit_gc */
1854                                true,  /* clear_all_soft_refs */
1855                                word_size);
1856   if (!gc_succeeded) {
1857     *succeeded = false;
1858     return NULL;
1859   }
1860 
1861   // Retry the allocation once more
1862   result = attempt_allocation_at_safepoint(word_size,
1863                                            context,
1864                                            true /* expect_null_mutator_alloc_region */);
1865   if (result != NULL) {
1866     assert(*succeeded, "sanity");
1867     return result;
1868   }
1869 
1870   assert(!collector_policy()->should_clear_all_soft_refs(),
1871          "Flag should have been handled and cleared prior to this point");
1872 
1873   // What else?  We might try synchronous finalization later.  If the total
1874   // space available is large enough for the allocation, then a more
1875   // complete compaction phase than we've tried so far might be
1876   // appropriate.
1877   assert(*succeeded, "sanity");
1878   return NULL;
1879 }
1880 
1881 // Attempting to expand the heap sufficiently
1882 // to support an allocation of the given "word_size".  If
1883 // successful, perform the allocation and return the address of the
1884 // allocated block, or else "NULL".
1885 
1886 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1887   assert_at_safepoint(true /* should_be_vm_thread */);
1888 
1889   verify_region_sets_optional();
1890 
1891   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1892   ergo_verbose1(ErgoHeapSizing,
1893                 "attempt heap expansion",
1894                 ergo_format_reason("allocation request failed")
1895                 ergo_format_byte("allocation request"),
1896                 word_size * HeapWordSize);
1897   if (expand(expand_bytes)) {
1898     _hrm.verify_optional();
1899     verify_region_sets_optional();
1900     return attempt_allocation_at_safepoint(word_size,
1901                                            context,
1902                                            false /* expect_null_mutator_alloc_region */);
1903   }
1904   return NULL;
1905 }
1906 
1907 bool G1CollectedHeap::expand(size_t expand_bytes) {
1908   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1909   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1910                                        HeapRegion::GrainBytes);
1911   ergo_verbose2(ErgoHeapSizing,
1912                 "expand the heap",
1913                 ergo_format_byte("requested expansion amount")
1914                 ergo_format_byte("attempted expansion amount"),
1915                 expand_bytes, aligned_expand_bytes);
1916 
1917   if (is_maximal_no_gc()) {
1918     ergo_verbose0(ErgoHeapSizing,
1919                       "did not expand the heap",
1920                       ergo_format_reason("heap already fully expanded"));
1921     return false;
1922   }
1923 
1924   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1925   assert(regions_to_expand > 0, "Must expand by at least one region");
1926 
1927   uint expanded_by = _hrm.expand_by(regions_to_expand);
1928 
1929   if (expanded_by > 0) {
1930     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1931     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1932     g1_policy()->record_new_heap_size(num_regions());
1933   } else {
1934     ergo_verbose0(ErgoHeapSizing,
1935                   "did not expand the heap",
1936                   ergo_format_reason("heap expansion operation failed"));
1937     // The expansion of the virtual storage space was unsuccessful.
1938     // Let's see if it was because we ran out of swap.
1939     if (G1ExitOnExpansionFailure &&
1940         _hrm.available() >= regions_to_expand) {
1941       // We had head room...
1942       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1943     }
1944   }
1945   return regions_to_expand > 0;
1946 }
1947 
1948 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1949   size_t aligned_shrink_bytes =
1950     ReservedSpace::page_align_size_down(shrink_bytes);
1951   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1952                                          HeapRegion::GrainBytes);
1953   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1954 
1955   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1956   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1957 
1958   ergo_verbose3(ErgoHeapSizing,
1959                 "shrink the heap",
1960                 ergo_format_byte("requested shrinking amount")
1961                 ergo_format_byte("aligned shrinking amount")
1962                 ergo_format_byte("attempted shrinking amount"),
1963                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1964   if (num_regions_removed > 0) {
1965     g1_policy()->record_new_heap_size(num_regions());
1966   } else {
1967     ergo_verbose0(ErgoHeapSizing,
1968                   "did not shrink the heap",
1969                   ergo_format_reason("heap shrinking operation failed"));
1970   }
1971 }
1972 
1973 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1974   verify_region_sets_optional();
1975 
1976   // We should only reach here at the end of a Full GC which means we
1977   // should not not be holding to any GC alloc regions. The method
1978   // below will make sure of that and do any remaining clean up.
1979   _allocator->abandon_gc_alloc_regions();
1980 
1981   // Instead of tearing down / rebuilding the free lists here, we
1982   // could instead use the remove_all_pending() method on free_list to
1983   // remove only the ones that we need to remove.
1984   tear_down_region_sets(true /* free_list_only */);
1985   shrink_helper(shrink_bytes);
1986   rebuild_region_sets(true /* free_list_only */);
1987 
1988   _hrm.verify_optional();
1989   verify_region_sets_optional();
1990 }
1991 
1992 // Public methods.
1993 
1994 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1995 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1996 #endif // _MSC_VER
1997 
1998 
1999 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2000   CollectedHeap(),
2001   _g1_policy(policy_),
2002   _dirty_card_queue_set(false),
2003   _into_cset_dirty_card_queue_set(false),
2004   _is_alive_closure_cm(this),
2005   _is_alive_closure_stw(this),
2006   _ref_processor_cm(NULL),
2007   _ref_processor_stw(NULL),
2008   _bot_shared(NULL),
2009   _cg1r(NULL),
2010   _g1mm(NULL),
2011   _refine_cte_cl(NULL),
2012   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2013   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2014   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2015   _humongous_reclaim_candidates(),
2016   _has_humongous_reclaim_candidates(false),
2017   _archive_allocator(NULL),
2018   _free_regions_coming(false),
2019   _young_list(new YoungList(this)),
2020   _gc_time_stamp(0),
2021   _summary_bytes_used(0),
2022   _survivor_evac_stats(YoungPLABSize, PLABWeight),
2023   _old_evac_stats(OldPLABSize, PLABWeight),
2024   _expand_heap_after_alloc_failure(true),
2025   _old_marking_cycles_started(0),
2026   _old_marking_cycles_completed(0),
2027   _heap_summary_sent(false),
2028   _in_cset_fast_test(),
2029   _dirty_cards_region_list(NULL),
2030   _worker_cset_start_region(NULL),
2031   _worker_cset_start_region_time_stamp(NULL),
2032   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2033   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2034   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2035   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2036 
2037   _workers = new WorkGang("GC Thread", ParallelGCThreads,
2038                           /* are_GC_task_threads */true,
2039                           /* are_ConcurrentGC_threads */false);
2040   _workers->initialize_workers();
2041 
2042   _allocator = G1Allocator::create_allocator(this);
2043   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2044 
2045   // Override the default _filler_array_max_size so that no humongous filler
2046   // objects are created.
2047   _filler_array_max_size = _humongous_object_threshold_in_words;
2048 
2049   uint n_queues = ParallelGCThreads;
2050   _task_queues = new RefToScanQueueSet(n_queues);
2051 
2052   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2053   assert(n_rem_sets > 0, "Invariant.");
2054 
2055   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2056   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2057   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2058 
2059   for (uint i = 0; i < n_queues; i++) {
2060     RefToScanQueue* q = new RefToScanQueue();
2061     q->initialize();
2062     _task_queues->register_queue(i, q);
2063     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2064   }
2065   clear_cset_start_regions();
2066 
2067   // Initialize the G1EvacuationFailureALot counters and flags.
2068   NOT_PRODUCT(reset_evacuation_should_fail();)
2069 
2070   guarantee(_task_queues != NULL, "task_queues allocation failure.");
2071 }
2072 
2073 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2074                                                                  size_t size,
2075                                                                  size_t translation_factor) {
2076   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2077   // Allocate a new reserved space, preferring to use large pages.
2078   ReservedSpace rs(size, preferred_page_size);
2079   G1RegionToSpaceMapper* result  =
2080     G1RegionToSpaceMapper::create_mapper(rs,
2081                                          size,
2082                                          rs.alignment(),
2083                                          HeapRegion::GrainBytes,
2084                                          translation_factor,
2085                                          mtGC);
2086   if (TracePageSizes) {
2087     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2088                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2089   }
2090   return result;
2091 }
2092 
2093 jint G1CollectedHeap::initialize() {
2094   CollectedHeap::pre_initialize();
2095   os::enable_vtime();
2096 
2097   G1Log::init();
2098 
2099   // Necessary to satisfy locking discipline assertions.
2100 
2101   MutexLocker x(Heap_lock);
2102 
2103   // We have to initialize the printer before committing the heap, as
2104   // it will be used then.
2105   _hr_printer.set_active(G1PrintHeapRegions);
2106 
2107   // While there are no constraints in the GC code that HeapWordSize
2108   // be any particular value, there are multiple other areas in the
2109   // system which believe this to be true (e.g. oop->object_size in some
2110   // cases incorrectly returns the size in wordSize units rather than
2111   // HeapWordSize).
2112   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2113 
2114   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2115   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2116   size_t heap_alignment = collector_policy()->heap_alignment();
2117 
2118   // Ensure that the sizes are properly aligned.
2119   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2120   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2121   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2122 
2123   _refine_cte_cl = new RefineCardTableEntryClosure();
2124 
2125   jint ecode = JNI_OK;
2126   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
2127   if (_cg1r == NULL) {
2128     return ecode;
2129   }
2130 
2131   // Reserve the maximum.
2132 
2133   // When compressed oops are enabled, the preferred heap base
2134   // is calculated by subtracting the requested size from the
2135   // 32Gb boundary and using the result as the base address for
2136   // heap reservation. If the requested size is not aligned to
2137   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2138   // into the ReservedHeapSpace constructor) then the actual
2139   // base of the reserved heap may end up differing from the
2140   // address that was requested (i.e. the preferred heap base).
2141   // If this happens then we could end up using a non-optimal
2142   // compressed oops mode.
2143 
2144   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2145                                                  heap_alignment);
2146 
2147   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2148 
2149   // Create the barrier set for the entire reserved region.
2150   G1SATBCardTableLoggingModRefBS* bs
2151     = new G1SATBCardTableLoggingModRefBS(reserved_region());
2152   bs->initialize();
2153   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2154   set_barrier_set(bs);
2155 
2156   // Also create a G1 rem set.
2157   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2158 
2159   // Carve out the G1 part of the heap.
2160 
2161   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2162   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2163   G1RegionToSpaceMapper* heap_storage =
2164     G1RegionToSpaceMapper::create_mapper(g1_rs,
2165                                          g1_rs.size(),
2166                                          page_size,
2167                                          HeapRegion::GrainBytes,
2168                                          1,
2169                                          mtJavaHeap);
2170   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2171                        max_byte_size, page_size,
2172                        heap_rs.base(),
2173                        heap_rs.size());
2174   heap_storage->set_mapping_changed_listener(&_listener);
2175 
2176   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2177   G1RegionToSpaceMapper* bot_storage =
2178     create_aux_memory_mapper("Block offset table",
2179                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2180                              G1BlockOffsetSharedArray::heap_map_factor());
2181 
2182   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2183   G1RegionToSpaceMapper* cardtable_storage =
2184     create_aux_memory_mapper("Card table",
2185                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2186                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
2187 
2188   G1RegionToSpaceMapper* card_counts_storage =
2189     create_aux_memory_mapper("Card counts table",
2190                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2191                              G1CardCounts::heap_map_factor());
2192 
2193   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2194   G1RegionToSpaceMapper* prev_bitmap_storage =
2195     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2196   G1RegionToSpaceMapper* next_bitmap_storage =
2197     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2198 
2199   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2200   g1_barrier_set()->initialize(cardtable_storage);
2201    // Do later initialization work for concurrent refinement.
2202   _cg1r->init(card_counts_storage);
2203 
2204   // 6843694 - ensure that the maximum region index can fit
2205   // in the remembered set structures.
2206   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2207   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2208 
2209   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2210   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2211   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2212             "too many cards per region");
2213 
2214   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2215 
2216   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2217 
2218   {
2219     HeapWord* start = _hrm.reserved().start();
2220     HeapWord* end = _hrm.reserved().end();
2221     size_t granularity = HeapRegion::GrainBytes;
2222 
2223     _in_cset_fast_test.initialize(start, end, granularity);
2224     _humongous_reclaim_candidates.initialize(start, end, granularity);
2225   }
2226 
2227   // Create the ConcurrentMark data structure and thread.
2228   // (Must do this late, so that "max_regions" is defined.)
2229   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2230   if (_cm == NULL || !_cm->completed_initialization()) {
2231     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2232     return JNI_ENOMEM;
2233   }
2234   _cmThread = _cm->cmThread();
2235 
2236   // Initialize the from_card cache structure of HeapRegionRemSet.
2237   HeapRegionRemSet::init_heap(max_regions());
2238 
2239   // Now expand into the initial heap size.
2240   if (!expand(init_byte_size)) {
2241     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2242     return JNI_ENOMEM;
2243   }
2244 
2245   // Perform any initialization actions delegated to the policy.
2246   g1_policy()->init();
2247 
2248   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2249                                                SATB_Q_FL_lock,
2250                                                G1SATBProcessCompletedThreshold,
2251                                                Shared_SATB_Q_lock);
2252 
2253   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2254                                                 DirtyCardQ_CBL_mon,
2255                                                 DirtyCardQ_FL_lock,
2256                                                 concurrent_g1_refine()->yellow_zone(),
2257                                                 concurrent_g1_refine()->red_zone(),
2258                                                 Shared_DirtyCardQ_lock);
2259 
2260   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2261                                     DirtyCardQ_CBL_mon,
2262                                     DirtyCardQ_FL_lock,
2263                                     -1, // never trigger processing
2264                                     -1, // no limit on length
2265                                     Shared_DirtyCardQ_lock,
2266                                     &JavaThread::dirty_card_queue_set());
2267 
2268   // Initialize the card queue set used to hold cards containing
2269   // references into the collection set.
2270   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2271                                              DirtyCardQ_CBL_mon,
2272                                              DirtyCardQ_FL_lock,
2273                                              -1, // never trigger processing
2274                                              -1, // no limit on length
2275                                              Shared_DirtyCardQ_lock,
2276                                              &JavaThread::dirty_card_queue_set());
2277 
2278   // Here we allocate the dummy HeapRegion that is required by the
2279   // G1AllocRegion class.
2280   HeapRegion* dummy_region = _hrm.get_dummy_region();
2281 
2282   // We'll re-use the same region whether the alloc region will
2283   // require BOT updates or not and, if it doesn't, then a non-young
2284   // region will complain that it cannot support allocations without
2285   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2286   dummy_region->set_eden();
2287   // Make sure it's full.
2288   dummy_region->set_top(dummy_region->end());
2289   G1AllocRegion::setup(this, dummy_region);
2290 
2291   _allocator->init_mutator_alloc_region();
2292 
2293   // Do create of the monitoring and management support so that
2294   // values in the heap have been properly initialized.
2295   _g1mm = new G1MonitoringSupport(this);
2296 
2297   G1StringDedup::initialize();
2298 
2299   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2300   for (uint i = 0; i < ParallelGCThreads; i++) {
2301     new (&_preserved_objs[i]) OopAndMarkOopStack();
2302   }
2303 
2304   return JNI_OK;
2305 }
2306 
2307 void G1CollectedHeap::stop() {
2308   // Stop all concurrent threads. We do this to make sure these threads
2309   // do not continue to execute and access resources (e.g. gclog_or_tty)
2310   // that are destroyed during shutdown.
2311   _cg1r->stop();
2312   _cmThread->stop();
2313   if (G1StringDedup::is_enabled()) {
2314     G1StringDedup::stop();
2315   }
2316 }
2317 
2318 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2319   return HeapRegion::max_region_size();
2320 }
2321 
2322 void G1CollectedHeap::post_initialize() {
2323   CollectedHeap::post_initialize();
2324   ref_processing_init();
2325 }
2326 
2327 void G1CollectedHeap::ref_processing_init() {
2328   // Reference processing in G1 currently works as follows:
2329   //
2330   // * There are two reference processor instances. One is
2331   //   used to record and process discovered references
2332   //   during concurrent marking; the other is used to
2333   //   record and process references during STW pauses
2334   //   (both full and incremental).
2335   // * Both ref processors need to 'span' the entire heap as
2336   //   the regions in the collection set may be dotted around.
2337   //
2338   // * For the concurrent marking ref processor:
2339   //   * Reference discovery is enabled at initial marking.
2340   //   * Reference discovery is disabled and the discovered
2341   //     references processed etc during remarking.
2342   //   * Reference discovery is MT (see below).
2343   //   * Reference discovery requires a barrier (see below).
2344   //   * Reference processing may or may not be MT
2345   //     (depending on the value of ParallelRefProcEnabled
2346   //     and ParallelGCThreads).
2347   //   * A full GC disables reference discovery by the CM
2348   //     ref processor and abandons any entries on it's
2349   //     discovered lists.
2350   //
2351   // * For the STW processor:
2352   //   * Non MT discovery is enabled at the start of a full GC.
2353   //   * Processing and enqueueing during a full GC is non-MT.
2354   //   * During a full GC, references are processed after marking.
2355   //
2356   //   * Discovery (may or may not be MT) is enabled at the start
2357   //     of an incremental evacuation pause.
2358   //   * References are processed near the end of a STW evacuation pause.
2359   //   * For both types of GC:
2360   //     * Discovery is atomic - i.e. not concurrent.
2361   //     * Reference discovery will not need a barrier.
2362 
2363   MemRegion mr = reserved_region();
2364 
2365   // Concurrent Mark ref processor
2366   _ref_processor_cm =
2367     new ReferenceProcessor(mr,    // span
2368                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2369                                 // mt processing
2370                            ParallelGCThreads,
2371                                 // degree of mt processing
2372                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2373                                 // mt discovery
2374                            MAX2(ParallelGCThreads, ConcGCThreads),
2375                                 // degree of mt discovery
2376                            false,
2377                                 // Reference discovery is not atomic
2378                            &_is_alive_closure_cm);
2379                                 // is alive closure
2380                                 // (for efficiency/performance)
2381 
2382   // STW ref processor
2383   _ref_processor_stw =
2384     new ReferenceProcessor(mr,    // span
2385                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2386                                 // mt processing
2387                            ParallelGCThreads,
2388                                 // degree of mt processing
2389                            (ParallelGCThreads > 1),
2390                                 // mt discovery
2391                            ParallelGCThreads,
2392                                 // degree of mt discovery
2393                            true,
2394                                 // Reference discovery is atomic
2395                            &_is_alive_closure_stw);
2396                                 // is alive closure
2397                                 // (for efficiency/performance)
2398 }
2399 
2400 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2401   return g1_policy();
2402 }
2403 
2404 size_t G1CollectedHeap::capacity() const {
2405   return _hrm.length() * HeapRegion::GrainBytes;
2406 }
2407 
2408 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2409   assert(!hr->is_continues_humongous(), "pre-condition");
2410   hr->reset_gc_time_stamp();
2411   if (hr->is_starts_humongous()) {
2412     uint first_index = hr->hrm_index() + 1;
2413     uint last_index = hr->last_hc_index();
2414     for (uint i = first_index; i < last_index; i += 1) {
2415       HeapRegion* chr = region_at(i);
2416       assert(chr->is_continues_humongous(), "sanity");
2417       chr->reset_gc_time_stamp();
2418     }
2419   }
2420 }
2421 
2422 #ifndef PRODUCT
2423 
2424 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2425 private:
2426   unsigned _gc_time_stamp;
2427   bool _failures;
2428 
2429 public:
2430   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2431     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2432 
2433   virtual bool doHeapRegion(HeapRegion* hr) {
2434     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2435     if (_gc_time_stamp != region_gc_time_stamp) {
2436       gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2437                              "expected %d", HR_FORMAT_PARAMS(hr),
2438                              region_gc_time_stamp, _gc_time_stamp);
2439       _failures = true;
2440     }
2441     return false;
2442   }
2443 
2444   bool failures() { return _failures; }
2445 };
2446 
2447 void G1CollectedHeap::check_gc_time_stamps() {
2448   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2449   heap_region_iterate(&cl);
2450   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2451 }
2452 #endif // PRODUCT
2453 
2454 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2455                                                  DirtyCardQueue* into_cset_dcq,
2456                                                  bool concurrent,
2457                                                  uint worker_i) {
2458   // Clean cards in the hot card cache
2459   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2460   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2461 
2462   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2463   size_t n_completed_buffers = 0;
2464   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2465     n_completed_buffers++;
2466   }
2467   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2468   dcqs.clear_n_completed_buffers();
2469   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2470 }
2471 
2472 // Computes the sum of the storage used by the various regions.
2473 size_t G1CollectedHeap::used() const {
2474   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2475   if (_archive_allocator != NULL) {
2476     result += _archive_allocator->used();
2477   }
2478   return result;
2479 }
2480 
2481 size_t G1CollectedHeap::used_unlocked() const {
2482   return _summary_bytes_used;
2483 }
2484 
2485 class SumUsedClosure: public HeapRegionClosure {
2486   size_t _used;
2487 public:
2488   SumUsedClosure() : _used(0) {}
2489   bool doHeapRegion(HeapRegion* r) {
2490     if (!r->is_continues_humongous()) {
2491       _used += r->used();
2492     }
2493     return false;
2494   }
2495   size_t result() { return _used; }
2496 };
2497 
2498 size_t G1CollectedHeap::recalculate_used() const {
2499   double recalculate_used_start = os::elapsedTime();
2500 
2501   SumUsedClosure blk;
2502   heap_region_iterate(&blk);
2503 
2504   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2505   return blk.result();
2506 }
2507 
2508 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2509   switch (cause) {
2510     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2511     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2512     case GCCause::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2513     case GCCause::_g1_humongous_allocation: return true;
2514     case GCCause::_update_allocation_context_stats_inc: return true;
2515     case GCCause::_wb_conc_mark:            return true;
2516     default:                                return false;
2517   }
2518 }
2519 
2520 #ifndef PRODUCT
2521 void G1CollectedHeap::allocate_dummy_regions() {
2522   // Let's fill up most of the region
2523   size_t word_size = HeapRegion::GrainWords - 1024;
2524   // And as a result the region we'll allocate will be humongous.
2525   guarantee(is_humongous(word_size), "sanity");
2526 
2527   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2528     // Let's use the existing mechanism for the allocation
2529     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2530                                                  AllocationContext::system());
2531     if (dummy_obj != NULL) {
2532       MemRegion mr(dummy_obj, word_size);
2533       CollectedHeap::fill_with_object(mr);
2534     } else {
2535       // If we can't allocate once, we probably cannot allocate
2536       // again. Let's get out of the loop.
2537       break;
2538     }
2539   }
2540 }
2541 #endif // !PRODUCT
2542 
2543 void G1CollectedHeap::increment_old_marking_cycles_started() {
2544   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2545     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2546     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2547     _old_marking_cycles_started, _old_marking_cycles_completed));
2548 
2549   _old_marking_cycles_started++;
2550 }
2551 
2552 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2553   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2554 
2555   // We assume that if concurrent == true, then the caller is a
2556   // concurrent thread that was joined the Suspendible Thread
2557   // Set. If there's ever a cheap way to check this, we should add an
2558   // assert here.
2559 
2560   // Given that this method is called at the end of a Full GC or of a
2561   // concurrent cycle, and those can be nested (i.e., a Full GC can
2562   // interrupt a concurrent cycle), the number of full collections
2563   // completed should be either one (in the case where there was no
2564   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2565   // behind the number of full collections started.
2566 
2567   // This is the case for the inner caller, i.e. a Full GC.
2568   assert(concurrent ||
2569          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2570          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2571          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2572                  "is inconsistent with _old_marking_cycles_completed = %u",
2573                  _old_marking_cycles_started, _old_marking_cycles_completed));
2574 
2575   // This is the case for the outer caller, i.e. the concurrent cycle.
2576   assert(!concurrent ||
2577          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2578          err_msg("for outer caller (concurrent cycle): "
2579                  "_old_marking_cycles_started = %u "
2580                  "is inconsistent with _old_marking_cycles_completed = %u",
2581                  _old_marking_cycles_started, _old_marking_cycles_completed));
2582 
2583   _old_marking_cycles_completed += 1;
2584 
2585   // We need to clear the "in_progress" flag in the CM thread before
2586   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2587   // is set) so that if a waiter requests another System.gc() it doesn't
2588   // incorrectly see that a marking cycle is still in progress.
2589   if (concurrent) {
2590     _cmThread->set_idle();
2591   }
2592 
2593   // This notify_all() will ensure that a thread that called
2594   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2595   // and it's waiting for a full GC to finish will be woken up. It is
2596   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2597   FullGCCount_lock->notify_all();
2598 }
2599 
2600 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2601   collector_state()->set_concurrent_cycle_started(true);
2602   _gc_timer_cm->register_gc_start(start_time);
2603 
2604   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2605   trace_heap_before_gc(_gc_tracer_cm);
2606 }
2607 
2608 void G1CollectedHeap::register_concurrent_cycle_end() {
2609   if (collector_state()->concurrent_cycle_started()) {
2610     if (_cm->has_aborted()) {
2611       _gc_tracer_cm->report_concurrent_mode_failure();
2612     }
2613 
2614     _gc_timer_cm->register_gc_end();
2615     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2616 
2617     // Clear state variables to prepare for the next concurrent cycle.
2618      collector_state()->set_concurrent_cycle_started(false);
2619     _heap_summary_sent = false;
2620   }
2621 }
2622 
2623 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2624   if (collector_state()->concurrent_cycle_started()) {
2625     // This function can be called when:
2626     //  the cleanup pause is run
2627     //  the concurrent cycle is aborted before the cleanup pause.
2628     //  the concurrent cycle is aborted after the cleanup pause,
2629     //   but before the concurrent cycle end has been registered.
2630     // Make sure that we only send the heap information once.
2631     if (!_heap_summary_sent) {
2632       trace_heap_after_gc(_gc_tracer_cm);
2633       _heap_summary_sent = true;
2634     }
2635   }
2636 }
2637 
2638 void G1CollectedHeap::collect(GCCause::Cause cause) {
2639   assert_heap_not_locked();
2640 
2641   uint gc_count_before;
2642   uint old_marking_count_before;
2643   uint full_gc_count_before;
2644   bool retry_gc;
2645 
2646   do {
2647     retry_gc = false;
2648 
2649     {
2650       MutexLocker ml(Heap_lock);
2651 
2652       // Read the GC count while holding the Heap_lock
2653       gc_count_before = total_collections();
2654       full_gc_count_before = total_full_collections();
2655       old_marking_count_before = _old_marking_cycles_started;
2656     }
2657 
2658     if (should_do_concurrent_full_gc(cause)) {
2659       // Schedule an initial-mark evacuation pause that will start a
2660       // concurrent cycle. We're setting word_size to 0 which means that
2661       // we are not requesting a post-GC allocation.
2662       VM_G1IncCollectionPause op(gc_count_before,
2663                                  0,     /* word_size */
2664                                  true,  /* should_initiate_conc_mark */
2665                                  g1_policy()->max_pause_time_ms(),
2666                                  cause);
2667       op.set_allocation_context(AllocationContext::current());
2668 
2669       VMThread::execute(&op);
2670       if (!op.pause_succeeded()) {
2671         if (old_marking_count_before == _old_marking_cycles_started) {
2672           retry_gc = op.should_retry_gc();
2673         } else {
2674           // A Full GC happened while we were trying to schedule the
2675           // initial-mark GC. No point in starting a new cycle given
2676           // that the whole heap was collected anyway.
2677         }
2678 
2679         if (retry_gc) {
2680           if (GC_locker::is_active_and_needs_gc()) {
2681             GC_locker::stall_until_clear();
2682           }
2683         }
2684       }
2685     } else {
2686       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2687           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2688 
2689         // Schedule a standard evacuation pause. We're setting word_size
2690         // to 0 which means that we are not requesting a post-GC allocation.
2691         VM_G1IncCollectionPause op(gc_count_before,
2692                                    0,     /* word_size */
2693                                    false, /* should_initiate_conc_mark */
2694                                    g1_policy()->max_pause_time_ms(),
2695                                    cause);
2696         VMThread::execute(&op);
2697       } else {
2698         // Schedule a Full GC.
2699         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2700         VMThread::execute(&op);
2701       }
2702     }
2703   } while (retry_gc);
2704 }
2705 
2706 bool G1CollectedHeap::is_in(const void* p) const {
2707   if (_hrm.reserved().contains(p)) {
2708     // Given that we know that p is in the reserved space,
2709     // heap_region_containing_raw() should successfully
2710     // return the containing region.
2711     HeapRegion* hr = heap_region_containing_raw(p);
2712     return hr->is_in(p);
2713   } else {
2714     return false;
2715   }
2716 }
2717 
2718 #ifdef ASSERT
2719 bool G1CollectedHeap::is_in_exact(const void* p) const {
2720   bool contains = reserved_region().contains(p);
2721   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2722   if (contains && available) {
2723     return true;
2724   } else {
2725     return false;
2726   }
2727 }
2728 #endif
2729 
2730 bool G1CollectedHeap::obj_in_cs(oop obj) {
2731   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2732   return r != NULL && r->in_collection_set();
2733 }
2734 
2735 // Iteration functions.
2736 
2737 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2738 
2739 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2740   ExtendedOopClosure* _cl;
2741 public:
2742   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2743   bool doHeapRegion(HeapRegion* r) {
2744     if (!r->is_continues_humongous()) {
2745       r->oop_iterate(_cl);
2746     }
2747     return false;
2748   }
2749 };
2750 
2751 // Iterates an ObjectClosure over all objects within a HeapRegion.
2752 
2753 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2754   ObjectClosure* _cl;
2755 public:
2756   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2757   bool doHeapRegion(HeapRegion* r) {
2758     if (!r->is_continues_humongous()) {
2759       r->object_iterate(_cl);
2760     }
2761     return false;
2762   }
2763 };
2764 
2765 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2766   IterateObjectClosureRegionClosure blk(cl);
2767   heap_region_iterate(&blk);
2768 }
2769 
2770 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2771   _hrm.iterate(cl);
2772 }
2773 
2774 void
2775 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2776                                          uint worker_id,
2777                                          HeapRegionClaimer *hrclaimer,
2778                                          bool concurrent) const {
2779   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2780 }
2781 
2782 // Clear the cached CSet starting regions and (more importantly)
2783 // the time stamps. Called when we reset the GC time stamp.
2784 void G1CollectedHeap::clear_cset_start_regions() {
2785   assert(_worker_cset_start_region != NULL, "sanity");
2786   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2787 
2788   for (uint i = 0; i < ParallelGCThreads; i++) {
2789     _worker_cset_start_region[i] = NULL;
2790     _worker_cset_start_region_time_stamp[i] = 0;
2791   }
2792 }
2793 
2794 // Given the id of a worker, obtain or calculate a suitable
2795 // starting region for iterating over the current collection set.
2796 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2797   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2798 
2799   HeapRegion* result = NULL;
2800   unsigned gc_time_stamp = get_gc_time_stamp();
2801 
2802   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2803     // Cached starting region for current worker was set
2804     // during the current pause - so it's valid.
2805     // Note: the cached starting heap region may be NULL
2806     // (when the collection set is empty).
2807     result = _worker_cset_start_region[worker_i];
2808     assert(result == NULL || result->in_collection_set(), "sanity");
2809     return result;
2810   }
2811 
2812   // The cached entry was not valid so let's calculate
2813   // a suitable starting heap region for this worker.
2814 
2815   // We want the parallel threads to start their collection
2816   // set iteration at different collection set regions to
2817   // avoid contention.
2818   // If we have:
2819   //          n collection set regions
2820   //          p threads
2821   // Then thread t will start at region floor ((t * n) / p)
2822 
2823   result = g1_policy()->collection_set();
2824   uint cs_size = g1_policy()->cset_region_length();
2825   uint active_workers = workers()->active_workers();
2826 
2827   uint end_ind   = (cs_size * worker_i) / active_workers;
2828   uint start_ind = 0;
2829 
2830   if (worker_i > 0 &&
2831       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2832     // Previous workers starting region is valid
2833     // so let's iterate from there
2834     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2835     result = _worker_cset_start_region[worker_i - 1];
2836   }
2837 
2838   for (uint i = start_ind; i < end_ind; i++) {
2839     result = result->next_in_collection_set();
2840   }
2841 
2842   // Note: the calculated starting heap region may be NULL
2843   // (when the collection set is empty).
2844   assert(result == NULL || result->in_collection_set(), "sanity");
2845   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2846          "should be updated only once per pause");
2847   _worker_cset_start_region[worker_i] = result;
2848   OrderAccess::storestore();
2849   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2850   return result;
2851 }
2852 
2853 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2854   HeapRegion* r = g1_policy()->collection_set();
2855   while (r != NULL) {
2856     HeapRegion* next = r->next_in_collection_set();
2857     if (cl->doHeapRegion(r)) {
2858       cl->incomplete();
2859       return;
2860     }
2861     r = next;
2862   }
2863 }
2864 
2865 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2866                                                   HeapRegionClosure *cl) {
2867   if (r == NULL) {
2868     // The CSet is empty so there's nothing to do.
2869     return;
2870   }
2871 
2872   assert(r->in_collection_set(),
2873          "Start region must be a member of the collection set.");
2874   HeapRegion* cur = r;
2875   while (cur != NULL) {
2876     HeapRegion* next = cur->next_in_collection_set();
2877     if (cl->doHeapRegion(cur) && false) {
2878       cl->incomplete();
2879       return;
2880     }
2881     cur = next;
2882   }
2883   cur = g1_policy()->collection_set();
2884   while (cur != r) {
2885     HeapRegion* next = cur->next_in_collection_set();
2886     if (cl->doHeapRegion(cur) && false) {
2887       cl->incomplete();
2888       return;
2889     }
2890     cur = next;
2891   }
2892 }
2893 
2894 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2895   HeapRegion* result = _hrm.next_region_in_heap(from);
2896   while (result != NULL && result->is_pinned()) {
2897     result = _hrm.next_region_in_heap(result);
2898   }
2899   return result;
2900 }
2901 
2902 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2903   HeapRegion* hr = heap_region_containing(addr);
2904   return hr->block_start(addr);
2905 }
2906 
2907 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2908   HeapRegion* hr = heap_region_containing(addr);
2909   return hr->block_size(addr);
2910 }
2911 
2912 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2913   HeapRegion* hr = heap_region_containing(addr);
2914   return hr->block_is_obj(addr);
2915 }
2916 
2917 bool G1CollectedHeap::supports_tlab_allocation() const {
2918   return true;
2919 }
2920 
2921 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2922   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2923 }
2924 
2925 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2926   return young_list()->eden_used_bytes();
2927 }
2928 
2929 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2930 // must be equal to the humongous object limit.
2931 size_t G1CollectedHeap::max_tlab_size() const {
2932   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2933 }
2934 
2935 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2936   AllocationContext_t context = AllocationContext::current();
2937   return _allocator->unsafe_max_tlab_alloc(context);
2938 }
2939 
2940 size_t G1CollectedHeap::max_capacity() const {
2941   return _hrm.reserved().byte_size();
2942 }
2943 
2944 jlong G1CollectedHeap::millis_since_last_gc() {
2945   // assert(false, "NYI");
2946   return 0;
2947 }
2948 
2949 void G1CollectedHeap::prepare_for_verify() {
2950   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2951     ensure_parsability(false);
2952   }
2953   g1_rem_set()->prepare_for_verify();
2954 }
2955 
2956 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2957                                               VerifyOption vo) {
2958   switch (vo) {
2959   case VerifyOption_G1UsePrevMarking:
2960     return hr->obj_allocated_since_prev_marking(obj);
2961   case VerifyOption_G1UseNextMarking:
2962     return hr->obj_allocated_since_next_marking(obj);
2963   case VerifyOption_G1UseMarkWord:
2964     return false;
2965   default:
2966     ShouldNotReachHere();
2967   }
2968   return false; // keep some compilers happy
2969 }
2970 
2971 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2972   switch (vo) {
2973   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2974   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2975   case VerifyOption_G1UseMarkWord:    return NULL;
2976   default:                            ShouldNotReachHere();
2977   }
2978   return NULL; // keep some compilers happy
2979 }
2980 
2981 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2982   switch (vo) {
2983   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2984   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2985   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2986   default:                            ShouldNotReachHere();
2987   }
2988   return false; // keep some compilers happy
2989 }
2990 
2991 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2992   switch (vo) {
2993   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2994   case VerifyOption_G1UseNextMarking: return "NTAMS";
2995   case VerifyOption_G1UseMarkWord:    return "NONE";
2996   default:                            ShouldNotReachHere();
2997   }
2998   return NULL; // keep some compilers happy
2999 }
3000 
3001 class VerifyRootsClosure: public OopClosure {
3002 private:
3003   G1CollectedHeap* _g1h;
3004   VerifyOption     _vo;
3005   bool             _failures;
3006 public:
3007   // _vo == UsePrevMarking -> use "prev" marking information,
3008   // _vo == UseNextMarking -> use "next" marking information,
3009   // _vo == UseMarkWord    -> use mark word from object header.
3010   VerifyRootsClosure(VerifyOption vo) :
3011     _g1h(G1CollectedHeap::heap()),
3012     _vo(vo),
3013     _failures(false) { }
3014 
3015   bool failures() { return _failures; }
3016 
3017   template <class T> void do_oop_nv(T* p) {
3018     T heap_oop = oopDesc::load_heap_oop(p);
3019     if (!oopDesc::is_null(heap_oop)) {
3020       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3021       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3022         gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3023                                "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3024         if (_vo == VerifyOption_G1UseMarkWord) {
3025           gclog_or_tty->print_cr("  Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3026         }
3027         obj->print_on(gclog_or_tty);
3028         _failures = true;
3029       }
3030     }
3031   }
3032 
3033   void do_oop(oop* p)       { do_oop_nv(p); }
3034   void do_oop(narrowOop* p) { do_oop_nv(p); }
3035 };
3036 
3037 class G1VerifyCodeRootOopClosure: public OopClosure {
3038   G1CollectedHeap* _g1h;
3039   OopClosure* _root_cl;
3040   nmethod* _nm;
3041   VerifyOption _vo;
3042   bool _failures;
3043 
3044   template <class T> void do_oop_work(T* p) {
3045     // First verify that this root is live
3046     _root_cl->do_oop(p);
3047 
3048     if (!G1VerifyHeapRegionCodeRoots) {
3049       // We're not verifying the code roots attached to heap region.
3050       return;
3051     }
3052 
3053     // Don't check the code roots during marking verification in a full GC
3054     if (_vo == VerifyOption_G1UseMarkWord) {
3055       return;
3056     }
3057 
3058     // Now verify that the current nmethod (which contains p) is
3059     // in the code root list of the heap region containing the
3060     // object referenced by p.
3061 
3062     T heap_oop = oopDesc::load_heap_oop(p);
3063     if (!oopDesc::is_null(heap_oop)) {
3064       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3065 
3066       // Now fetch the region containing the object
3067       HeapRegion* hr = _g1h->heap_region_containing(obj);
3068       HeapRegionRemSet* hrrs = hr->rem_set();
3069       // Verify that the strong code root list for this region
3070       // contains the nmethod
3071       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3072         gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3073                                "from nmethod " PTR_FORMAT " not in strong "
3074                                "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3075                                p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3076         _failures = true;
3077       }
3078     }
3079   }
3080 
3081 public:
3082   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3083     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3084 
3085   void do_oop(oop* p) { do_oop_work(p); }
3086   void do_oop(narrowOop* p) { do_oop_work(p); }
3087 
3088   void set_nmethod(nmethod* nm) { _nm = nm; }
3089   bool failures() { return _failures; }
3090 };
3091 
3092 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3093   G1VerifyCodeRootOopClosure* _oop_cl;
3094 
3095 public:
3096   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3097     _oop_cl(oop_cl) {}
3098 
3099   void do_code_blob(CodeBlob* cb) {
3100     nmethod* nm = cb->as_nmethod_or_null();
3101     if (nm != NULL) {
3102       _oop_cl->set_nmethod(nm);
3103       nm->oops_do(_oop_cl);
3104     }
3105   }
3106 };
3107 
3108 class YoungRefCounterClosure : public OopClosure {
3109   G1CollectedHeap* _g1h;
3110   int              _count;
3111  public:
3112   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3113   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3114   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3115 
3116   int count() { return _count; }
3117   void reset_count() { _count = 0; };
3118 };
3119 
3120 class VerifyKlassClosure: public KlassClosure {
3121   YoungRefCounterClosure _young_ref_counter_closure;
3122   OopClosure *_oop_closure;
3123  public:
3124   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3125   void do_klass(Klass* k) {
3126     k->oops_do(_oop_closure);
3127 
3128     _young_ref_counter_closure.reset_count();
3129     k->oops_do(&_young_ref_counter_closure);
3130     if (_young_ref_counter_closure.count() > 0) {
3131       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3132     }
3133   }
3134 };
3135 
3136 class VerifyLivenessOopClosure: public OopClosure {
3137   G1CollectedHeap* _g1h;
3138   VerifyOption _vo;
3139 public:
3140   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3141     _g1h(g1h), _vo(vo)
3142   { }
3143   void do_oop(narrowOop *p) { do_oop_work(p); }
3144   void do_oop(      oop *p) { do_oop_work(p); }
3145 
3146   template <class T> void do_oop_work(T *p) {
3147     oop obj = oopDesc::load_decode_heap_oop(p);
3148     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3149               "Dead object referenced by a not dead object");
3150   }
3151 };
3152 
3153 class VerifyObjsInRegionClosure: public ObjectClosure {
3154 private:
3155   G1CollectedHeap* _g1h;
3156   size_t _live_bytes;
3157   HeapRegion *_hr;
3158   VerifyOption _vo;
3159 public:
3160   // _vo == UsePrevMarking -> use "prev" marking information,
3161   // _vo == UseNextMarking -> use "next" marking information,
3162   // _vo == UseMarkWord    -> use mark word from object header.
3163   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3164     : _live_bytes(0), _hr(hr), _vo(vo) {
3165     _g1h = G1CollectedHeap::heap();
3166   }
3167   void do_object(oop o) {
3168     VerifyLivenessOopClosure isLive(_g1h, _vo);
3169     assert(o != NULL, "Huh?");
3170     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3171       // If the object is alive according to the mark word,
3172       // then verify that the marking information agrees.
3173       // Note we can't verify the contra-positive of the
3174       // above: if the object is dead (according to the mark
3175       // word), it may not be marked, or may have been marked
3176       // but has since became dead, or may have been allocated
3177       // since the last marking.
3178       if (_vo == VerifyOption_G1UseMarkWord) {
3179         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3180       }
3181 
3182       o->oop_iterate_no_header(&isLive);
3183       if (!_hr->obj_allocated_since_prev_marking(o)) {
3184         size_t obj_size = o->size();    // Make sure we don't overflow
3185         _live_bytes += (obj_size * HeapWordSize);
3186       }
3187     }
3188   }
3189   size_t live_bytes() { return _live_bytes; }
3190 };
3191 
3192 class VerifyArchiveOopClosure: public OopClosure {
3193 public:
3194   VerifyArchiveOopClosure(HeapRegion *hr) { }
3195   void do_oop(narrowOop *p) { do_oop_work(p); }
3196   void do_oop(      oop *p) { do_oop_work(p); }
3197 
3198   template <class T> void do_oop_work(T *p) {
3199     oop obj = oopDesc::load_decode_heap_oop(p);
3200     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3201               err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3202                       p2i(p), p2i(obj)));
3203   }
3204 };
3205 
3206 class VerifyArchiveRegionClosure: public ObjectClosure {
3207 public:
3208   VerifyArchiveRegionClosure(HeapRegion *hr) { }
3209   // Verify that all object pointers are to archive regions.
3210   void do_object(oop o) {
3211     VerifyArchiveOopClosure checkOop(NULL);
3212     assert(o != NULL, "Should not be here for NULL oops");
3213     o->oop_iterate_no_header(&checkOop);
3214   }
3215 };
3216 
3217 class VerifyRegionClosure: public HeapRegionClosure {
3218 private:
3219   bool             _par;
3220   VerifyOption     _vo;
3221   bool             _failures;
3222 public:
3223   // _vo == UsePrevMarking -> use "prev" marking information,
3224   // _vo == UseNextMarking -> use "next" marking information,
3225   // _vo == UseMarkWord    -> use mark word from object header.
3226   VerifyRegionClosure(bool par, VerifyOption vo)
3227     : _par(par),
3228       _vo(vo),
3229       _failures(false) {}
3230 
3231   bool failures() {
3232     return _failures;
3233   }
3234 
3235   bool doHeapRegion(HeapRegion* r) {
3236     // For archive regions, verify there are no heap pointers to
3237     // non-pinned regions. For all others, verify liveness info.
3238     if (r->is_archive()) {
3239       VerifyArchiveRegionClosure verify_oop_pointers(r);
3240       r->object_iterate(&verify_oop_pointers);
3241       return true;
3242     }
3243     if (!r->is_continues_humongous()) {
3244       bool failures = false;
3245       r->verify(_vo, &failures);
3246       if (failures) {
3247         _failures = true;
3248       } else {
3249         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3250         r->object_iterate(&not_dead_yet_cl);
3251         if (_vo != VerifyOption_G1UseNextMarking) {
3252           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3253             gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3254                                    "max_live_bytes " SIZE_FORMAT " "
3255                                    "< calculated " SIZE_FORMAT,
3256                                    p2i(r->bottom()), p2i(r->end()),
3257                                    r->max_live_bytes(),
3258                                  not_dead_yet_cl.live_bytes());
3259             _failures = true;
3260           }
3261         } else {
3262           // When vo == UseNextMarking we cannot currently do a sanity
3263           // check on the live bytes as the calculation has not been
3264           // finalized yet.
3265         }
3266       }
3267     }
3268     return false; // stop the region iteration if we hit a failure
3269   }
3270 };
3271 
3272 // This is the task used for parallel verification of the heap regions
3273 
3274 class G1ParVerifyTask: public AbstractGangTask {
3275 private:
3276   G1CollectedHeap*  _g1h;
3277   VerifyOption      _vo;
3278   bool              _failures;
3279   HeapRegionClaimer _hrclaimer;
3280 
3281 public:
3282   // _vo == UsePrevMarking -> use "prev" marking information,
3283   // _vo == UseNextMarking -> use "next" marking information,
3284   // _vo == UseMarkWord    -> use mark word from object header.
3285   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3286       AbstractGangTask("Parallel verify task"),
3287       _g1h(g1h),
3288       _vo(vo),
3289       _failures(false),
3290       _hrclaimer(g1h->workers()->active_workers()) {}
3291 
3292   bool failures() {
3293     return _failures;
3294   }
3295 
3296   void work(uint worker_id) {
3297     HandleMark hm;
3298     VerifyRegionClosure blk(true, _vo);
3299     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3300     if (blk.failures()) {
3301       _failures = true;
3302     }
3303   }
3304 };
3305 
3306 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3307   if (SafepointSynchronize::is_at_safepoint()) {
3308     assert(Thread::current()->is_VM_thread(),
3309            "Expected to be executed serially by the VM thread at this point");
3310 
3311     if (!silent) { gclog_or_tty->print("Roots "); }
3312     VerifyRootsClosure rootsCl(vo);
3313     VerifyKlassClosure klassCl(this, &rootsCl);
3314     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3315 
3316     // We apply the relevant closures to all the oops in the
3317     // system dictionary, class loader data graph, the string table
3318     // and the nmethods in the code cache.
3319     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3320     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3321 
3322     {
3323       G1RootProcessor root_processor(this, 1);
3324       root_processor.process_all_roots(&rootsCl,
3325                                        &cldCl,
3326                                        &blobsCl);
3327     }
3328 
3329     bool failures = rootsCl.failures() || codeRootsCl.failures();
3330 
3331     if (vo != VerifyOption_G1UseMarkWord) {
3332       // If we're verifying during a full GC then the region sets
3333       // will have been torn down at the start of the GC. Therefore
3334       // verifying the region sets will fail. So we only verify
3335       // the region sets when not in a full GC.
3336       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3337       verify_region_sets();
3338     }
3339 
3340     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3341     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3342 
3343       G1ParVerifyTask task(this, vo);
3344       workers()->run_task(&task);
3345       if (task.failures()) {
3346         failures = true;
3347       }
3348 
3349     } else {
3350       VerifyRegionClosure blk(false, vo);
3351       heap_region_iterate(&blk);
3352       if (blk.failures()) {
3353         failures = true;
3354       }
3355     }
3356 
3357     if (G1StringDedup::is_enabled()) {
3358       if (!silent) gclog_or_tty->print("StrDedup ");
3359       G1StringDedup::verify();
3360     }
3361 
3362     if (failures) {
3363       gclog_or_tty->print_cr("Heap:");
3364       // It helps to have the per-region information in the output to
3365       // help us track down what went wrong. This is why we call
3366       // print_extended_on() instead of print_on().
3367       print_extended_on(gclog_or_tty);
3368       gclog_or_tty->cr();
3369       gclog_or_tty->flush();
3370     }
3371     guarantee(!failures, "there should not have been any failures");
3372   } else {
3373     if (!silent) {
3374       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3375       if (G1StringDedup::is_enabled()) {
3376         gclog_or_tty->print(", StrDedup");
3377       }
3378       gclog_or_tty->print(") ");
3379     }
3380   }
3381 }
3382 
3383 void G1CollectedHeap::verify(bool silent) {
3384   verify(silent, VerifyOption_G1UsePrevMarking);
3385 }
3386 
3387 double G1CollectedHeap::verify(bool guard, const char* msg) {
3388   double verify_time_ms = 0.0;
3389 
3390   if (guard && total_collections() >= VerifyGCStartAt) {
3391     double verify_start = os::elapsedTime();
3392     HandleMark hm;  // Discard invalid handles created during verification
3393     prepare_for_verify();
3394     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3395     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3396   }
3397 
3398   return verify_time_ms;
3399 }
3400 
3401 void G1CollectedHeap::verify_before_gc() {
3402   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3403   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3404 }
3405 
3406 void G1CollectedHeap::verify_after_gc() {
3407   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3408   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3409 }
3410 
3411 class PrintRegionClosure: public HeapRegionClosure {
3412   outputStream* _st;
3413 public:
3414   PrintRegionClosure(outputStream* st) : _st(st) {}
3415   bool doHeapRegion(HeapRegion* r) {
3416     r->print_on(_st);
3417     return false;
3418   }
3419 };
3420 
3421 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3422                                        const HeapRegion* hr,
3423                                        const VerifyOption vo) const {
3424   switch (vo) {
3425   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3426   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3427   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3428   default:                            ShouldNotReachHere();
3429   }
3430   return false; // keep some compilers happy
3431 }
3432 
3433 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3434                                        const VerifyOption vo) const {
3435   switch (vo) {
3436   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3437   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3438   case VerifyOption_G1UseMarkWord: {
3439     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3440     return !obj->is_gc_marked() && !hr->is_archive();
3441   }
3442   default:                            ShouldNotReachHere();
3443   }
3444   return false; // keep some compilers happy
3445 }
3446 
3447 void G1CollectedHeap::print_on(outputStream* st) const {
3448   st->print(" %-20s", "garbage-first heap");
3449   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3450             capacity()/K, used_unlocked()/K);
3451   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3452             p2i(_hrm.reserved().start()),
3453             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3454             p2i(_hrm.reserved().end()));
3455   st->cr();
3456   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3457   uint young_regions = _young_list->length();
3458   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3459             (size_t) young_regions * HeapRegion::GrainBytes / K);
3460   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3461   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3462             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3463   st->cr();
3464   MetaspaceAux::print_on(st);
3465 }
3466 
3467 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3468   print_on(st);
3469 
3470   // Print the per-region information.
3471   st->cr();
3472   st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3473                "HS=humongous(starts), HC=humongous(continues), "
3474                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3475                "PTAMS=previous top-at-mark-start, "
3476                "NTAMS=next top-at-mark-start)");
3477   PrintRegionClosure blk(st);
3478   heap_region_iterate(&blk);
3479 }
3480 
3481 void G1CollectedHeap::print_on_error(outputStream* st) const {
3482   this->CollectedHeap::print_on_error(st);
3483 
3484   if (_cm != NULL) {
3485     st->cr();
3486     _cm->print_on_error(st);
3487   }
3488 }
3489 
3490 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3491   workers()->print_worker_threads_on(st);
3492   _cmThread->print_on(st);
3493   st->cr();
3494   _cm->print_worker_threads_on(st);
3495   _cg1r->print_worker_threads_on(st);
3496   if (G1StringDedup::is_enabled()) {
3497     G1StringDedup::print_worker_threads_on(st);
3498   }
3499 }
3500 
3501 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3502   workers()->threads_do(tc);
3503   tc->do_thread(_cmThread);
3504   _cg1r->threads_do(tc);
3505   if (G1StringDedup::is_enabled()) {
3506     G1StringDedup::threads_do(tc);
3507   }
3508 }
3509 
3510 void G1CollectedHeap::print_tracing_info() const {
3511   // We'll overload this to mean "trace GC pause statistics."
3512   if (TraceYoungGenTime || TraceOldGenTime) {
3513     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3514     // to that.
3515     g1_policy()->print_tracing_info();
3516   }
3517   if (G1SummarizeRSetStats) {
3518     g1_rem_set()->print_summary_info();
3519   }
3520   if (G1SummarizeConcMark) {
3521     concurrent_mark()->print_summary_info();
3522   }
3523   g1_policy()->print_yg_surv_rate_info();
3524 }
3525 
3526 #ifndef PRODUCT
3527 // Helpful for debugging RSet issues.
3528 
3529 class PrintRSetsClosure : public HeapRegionClosure {
3530 private:
3531   const char* _msg;
3532   size_t _occupied_sum;
3533 
3534 public:
3535   bool doHeapRegion(HeapRegion* r) {
3536     HeapRegionRemSet* hrrs = r->rem_set();
3537     size_t occupied = hrrs->occupied();
3538     _occupied_sum += occupied;
3539 
3540     gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3541                            HR_FORMAT_PARAMS(r));
3542     if (occupied == 0) {
3543       gclog_or_tty->print_cr("  RSet is empty");
3544     } else {
3545       hrrs->print();
3546     }
3547     gclog_or_tty->print_cr("----------");
3548     return false;
3549   }
3550 
3551   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3552     gclog_or_tty->cr();
3553     gclog_or_tty->print_cr("========================================");
3554     gclog_or_tty->print_cr("%s", msg);
3555     gclog_or_tty->cr();
3556   }
3557 
3558   ~PrintRSetsClosure() {
3559     gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3560     gclog_or_tty->print_cr("========================================");
3561     gclog_or_tty->cr();
3562   }
3563 };
3564 
3565 void G1CollectedHeap::print_cset_rsets() {
3566   PrintRSetsClosure cl("Printing CSet RSets");
3567   collection_set_iterate(&cl);
3568 }
3569 
3570 void G1CollectedHeap::print_all_rsets() {
3571   PrintRSetsClosure cl("Printing All RSets");;
3572   heap_region_iterate(&cl);
3573 }
3574 #endif // PRODUCT
3575 
3576 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3577   YoungList* young_list = heap()->young_list();
3578 
3579   size_t eden_used_bytes = young_list->eden_used_bytes();
3580   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3581 
3582   size_t eden_capacity_bytes =
3583     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3584 
3585   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3586   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3587 }
3588 
3589 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3590   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3591                        stats->unused(), stats->used(), stats->region_end_waste(),
3592                        stats->regions_filled(), stats->direct_allocated(),
3593                        stats->failure_used(), stats->failure_waste());
3594 }
3595 
3596 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3597   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3598   gc_tracer->report_gc_heap_summary(when, heap_summary);
3599 
3600   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3601   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3602 }
3603 
3604 
3605 G1CollectedHeap* G1CollectedHeap::heap() {
3606   CollectedHeap* heap = Universe::heap();
3607   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3608   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3609   return (G1CollectedHeap*)heap;
3610 }
3611 
3612 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3613   // always_do_update_barrier = false;
3614   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3615   // Fill TLAB's and such
3616   accumulate_statistics_all_tlabs();
3617   ensure_parsability(true);
3618 
3619   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3620       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3621     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3622   }
3623 }
3624 
3625 void G1CollectedHeap::gc_epilogue(bool full) {
3626 
3627   if (G1SummarizeRSetStats &&
3628       (G1SummarizeRSetStatsPeriod > 0) &&
3629       // we are at the end of the GC. Total collections has already been increased.
3630       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3631     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3632   }
3633 
3634   // FIXME: what is this about?
3635   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3636   // is set.
3637 #if defined(COMPILER2) || INCLUDE_JVMCI
3638   assert(DerivedPointerTable::is_empty(), "derived pointer present");
3639 #endif
3640   // always_do_update_barrier = true;
3641 
3642   resize_all_tlabs();
3643   allocation_context_stats().update(full);
3644 
3645   // We have just completed a GC. Update the soft reference
3646   // policy with the new heap occupancy
3647   Universe::update_heap_info_at_gc();
3648 }
3649 
3650 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3651                                                uint gc_count_before,
3652                                                bool* succeeded,
3653                                                GCCause::Cause gc_cause) {
3654   assert_heap_not_locked_and_not_at_safepoint();
3655   g1_policy()->record_stop_world_start();
3656   VM_G1IncCollectionPause op(gc_count_before,
3657                              word_size,
3658                              false, /* should_initiate_conc_mark */
3659                              g1_policy()->max_pause_time_ms(),
3660                              gc_cause);
3661 
3662   op.set_allocation_context(AllocationContext::current());
3663   VMThread::execute(&op);
3664 
3665   HeapWord* result = op.result();
3666   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3667   assert(result == NULL || ret_succeeded,
3668          "the result should be NULL if the VM did not succeed");
3669   *succeeded = ret_succeeded;
3670 
3671   assert_heap_not_locked();
3672   return result;
3673 }
3674 
3675 void
3676 G1CollectedHeap::doConcurrentMark() {
3677   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3678   if (!_cmThread->in_progress()) {
3679     _cmThread->set_started();
3680     CGC_lock->notify();
3681   }
3682 }
3683 
3684 size_t G1CollectedHeap::pending_card_num() {
3685   size_t extra_cards = 0;
3686   JavaThread *curr = Threads::first();
3687   while (curr != NULL) {
3688     DirtyCardQueue& dcq = curr->dirty_card_queue();
3689     extra_cards += dcq.size();
3690     curr = curr->next();
3691   }
3692   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3693   size_t buffer_size = dcqs.buffer_size();
3694   size_t buffer_num = dcqs.completed_buffers_num();
3695 
3696   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3697   // in bytes - not the number of 'entries'. We need to convert
3698   // into a number of cards.
3699   return (buffer_size * buffer_num + extra_cards) / oopSize;
3700 }
3701 
3702 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3703  private:
3704   size_t _total_humongous;
3705   size_t _candidate_humongous;
3706 
3707   DirtyCardQueue _dcq;
3708 
3709   // We don't nominate objects with many remembered set entries, on
3710   // the assumption that such objects are likely still live.
3711   bool is_remset_small(HeapRegion* region) const {
3712     HeapRegionRemSet* const rset = region->rem_set();
3713     return G1EagerReclaimHumongousObjectsWithStaleRefs
3714       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3715       : rset->is_empty();
3716   }
3717 
3718   bool is_typeArray_region(HeapRegion* region) const {
3719     return oop(region->bottom())->is_typeArray();
3720   }
3721 
3722   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3723     assert(region->is_starts_humongous(), "Must start a humongous object");
3724 
3725     // Candidate selection must satisfy the following constraints
3726     // while concurrent marking is in progress:
3727     //
3728     // * In order to maintain SATB invariants, an object must not be
3729     // reclaimed if it was allocated before the start of marking and
3730     // has not had its references scanned.  Such an object must have
3731     // its references (including type metadata) scanned to ensure no
3732     // live objects are missed by the marking process.  Objects
3733     // allocated after the start of concurrent marking don't need to
3734     // be scanned.
3735     //
3736     // * An object must not be reclaimed if it is on the concurrent
3737     // mark stack.  Objects allocated after the start of concurrent
3738     // marking are never pushed on the mark stack.
3739     //
3740     // Nominating only objects allocated after the start of concurrent
3741     // marking is sufficient to meet both constraints.  This may miss
3742     // some objects that satisfy the constraints, but the marking data
3743     // structures don't support efficiently performing the needed
3744     // additional tests or scrubbing of the mark stack.
3745     //
3746     // However, we presently only nominate is_typeArray() objects.
3747     // A humongous object containing references induces remembered
3748     // set entries on other regions.  In order to reclaim such an
3749     // object, those remembered sets would need to be cleaned up.
3750     //
3751     // We also treat is_typeArray() objects specially, allowing them
3752     // to be reclaimed even if allocated before the start of
3753     // concurrent mark.  For this we rely on mark stack insertion to
3754     // exclude is_typeArray() objects, preventing reclaiming an object
3755     // that is in the mark stack.  We also rely on the metadata for
3756     // such objects to be built-in and so ensured to be kept live.
3757     // Frequent allocation and drop of large binary blobs is an
3758     // important use case for eager reclaim, and this special handling
3759     // may reduce needed headroom.
3760 
3761     return is_typeArray_region(region) && is_remset_small(region);
3762   }
3763 
3764  public:
3765   RegisterHumongousWithInCSetFastTestClosure()
3766   : _total_humongous(0),
3767     _candidate_humongous(0),
3768     _dcq(&JavaThread::dirty_card_queue_set()) {
3769   }
3770 
3771   virtual bool doHeapRegion(HeapRegion* r) {
3772     if (!r->is_starts_humongous()) {
3773       return false;
3774     }
3775     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3776 
3777     bool is_candidate = humongous_region_is_candidate(g1h, r);
3778     uint rindex = r->hrm_index();
3779     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3780     if (is_candidate) {
3781       _candidate_humongous++;
3782       g1h->register_humongous_region_with_cset(rindex);
3783       // Is_candidate already filters out humongous object with large remembered sets.
3784       // If we have a humongous object with a few remembered sets, we simply flush these
3785       // remembered set entries into the DCQS. That will result in automatic
3786       // re-evaluation of their remembered set entries during the following evacuation
3787       // phase.
3788       if (!r->rem_set()->is_empty()) {
3789         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3790                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3791         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3792         HeapRegionRemSetIterator hrrs(r->rem_set());
3793         size_t card_index;
3794         while (hrrs.has_next(card_index)) {
3795           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3796           // The remembered set might contain references to already freed
3797           // regions. Filter out such entries to avoid failing card table
3798           // verification.
3799           if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3800             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3801               *card_ptr = CardTableModRefBS::dirty_card_val();
3802               _dcq.enqueue(card_ptr);
3803             }
3804           }
3805         }
3806         r->rem_set()->clear_locked();
3807       }
3808       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3809     }
3810     _total_humongous++;
3811 
3812     return false;
3813   }
3814 
3815   size_t total_humongous() const { return _total_humongous; }
3816   size_t candidate_humongous() const { return _candidate_humongous; }
3817 
3818   void flush_rem_set_entries() { _dcq.flush(); }
3819 };
3820 
3821 void G1CollectedHeap::register_humongous_regions_with_cset() {
3822   if (!G1EagerReclaimHumongousObjects) {
3823     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3824     return;
3825   }
3826   double time = os::elapsed_counter();
3827 
3828   // Collect reclaim candidate information and register candidates with cset.
3829   RegisterHumongousWithInCSetFastTestClosure cl;
3830   heap_region_iterate(&cl);
3831 
3832   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3833   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3834                                                                   cl.total_humongous(),
3835                                                                   cl.candidate_humongous());
3836   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3837 
3838   // Finally flush all remembered set entries to re-check into the global DCQS.
3839   cl.flush_rem_set_entries();
3840 }
3841 
3842 #ifdef ASSERT
3843 class VerifyCSetClosure: public HeapRegionClosure {
3844 public:
3845   bool doHeapRegion(HeapRegion* hr) {
3846     // Here we check that the CSet region's RSet is ready for parallel
3847     // iteration. The fields that we'll verify are only manipulated
3848     // when the region is part of a CSet and is collected. Afterwards,
3849     // we reset these fields when we clear the region's RSet (when the
3850     // region is freed) so they are ready when the region is
3851     // re-allocated. The only exception to this is if there's an
3852     // evacuation failure and instead of freeing the region we leave
3853     // it in the heap. In that case, we reset these fields during
3854     // evacuation failure handling.
3855     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3856 
3857     // Here's a good place to add any other checks we'd like to
3858     // perform on CSet regions.
3859     return false;
3860   }
3861 };
3862 #endif // ASSERT
3863 
3864 uint G1CollectedHeap::num_task_queues() const {
3865   return _task_queues->size();
3866 }
3867 
3868 #if TASKQUEUE_STATS
3869 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3870   st->print_raw_cr("GC Task Stats");
3871   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3872   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3873 }
3874 
3875 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3876   print_taskqueue_stats_hdr(st);
3877 
3878   TaskQueueStats totals;
3879   const uint n = num_task_queues();
3880   for (uint i = 0; i < n; ++i) {
3881     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3882     totals += task_queue(i)->stats;
3883   }
3884   st->print_raw("tot "); totals.print(st); st->cr();
3885 
3886   DEBUG_ONLY(totals.verify());
3887 }
3888 
3889 void G1CollectedHeap::reset_taskqueue_stats() {
3890   const uint n = num_task_queues();
3891   for (uint i = 0; i < n; ++i) {
3892     task_queue(i)->stats.reset();
3893   }
3894 }
3895 #endif // TASKQUEUE_STATS
3896 
3897 void G1CollectedHeap::log_gc_header() {
3898   if (!G1Log::fine()) {
3899     return;
3900   }
3901 
3902   gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3903 
3904   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3905     .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3906     .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3907 
3908   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3909 }
3910 
3911 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3912   if (!G1Log::fine()) {
3913     return;
3914   }
3915 
3916   if (G1Log::finer()) {
3917     if (evacuation_failed()) {
3918       gclog_or_tty->print(" (to-space exhausted)");
3919     }
3920     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3921     g1_policy()->phase_times()->note_gc_end();
3922     g1_policy()->phase_times()->print(pause_time_sec);
3923     g1_policy()->print_detailed_heap_transition();
3924   } else {
3925     if (evacuation_failed()) {
3926       gclog_or_tty->print("--");
3927     }
3928     g1_policy()->print_heap_transition();
3929     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3930   }
3931   gclog_or_tty->flush();
3932 }
3933 
3934 void G1CollectedHeap::wait_for_root_region_scanning() {
3935   double scan_wait_start = os::elapsedTime();
3936   // We have to wait until the CM threads finish scanning the
3937   // root regions as it's the only way to ensure that all the
3938   // objects on them have been correctly scanned before we start
3939   // moving them during the GC.
3940   bool waited = _cm->root_regions()->wait_until_scan_finished();
3941   double wait_time_ms = 0.0;
3942   if (waited) {
3943     double scan_wait_end = os::elapsedTime();
3944     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3945   }
3946   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3947 }
3948 
3949 bool
3950 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3951   assert_at_safepoint(true /* should_be_vm_thread */);
3952   guarantee(!is_gc_active(), "collection is not reentrant");
3953 
3954   if (GC_locker::check_active_before_gc()) {
3955     return false;
3956   }
3957 
3958   _gc_timer_stw->register_gc_start();
3959 
3960   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3961 
3962   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3963   ResourceMark rm;
3964 
3965   wait_for_root_region_scanning();
3966 
3967   G1Log::update_level();
3968   print_heap_before_gc();
3969   trace_heap_before_gc(_gc_tracer_stw);
3970 
3971   verify_region_sets_optional();
3972   verify_dirty_young_regions();
3973 
3974   // This call will decide whether this pause is an initial-mark
3975   // pause. If it is, during_initial_mark_pause() will return true
3976   // for the duration of this pause.
3977   g1_policy()->decide_on_conc_mark_initiation();
3978 
3979   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3980   assert(!collector_state()->during_initial_mark_pause() ||
3981           collector_state()->gcs_are_young(), "sanity");
3982 
3983   // We also do not allow mixed GCs during marking.
3984   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3985 
3986   // Record whether this pause is an initial mark. When the current
3987   // thread has completed its logging output and it's safe to signal
3988   // the CM thread, the flag's value in the policy has been reset.
3989   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3990 
3991   // Inner scope for scope based logging, timers, and stats collection
3992   {
3993     EvacuationInfo evacuation_info;
3994 
3995     if (collector_state()->during_initial_mark_pause()) {
3996       // We are about to start a marking cycle, so we increment the
3997       // full collection counter.
3998       increment_old_marking_cycles_started();
3999       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4000     }
4001 
4002     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4003 
4004     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4005 
4006     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4007                                                                   workers()->active_workers(),
4008                                                                   Threads::number_of_non_daemon_threads());
4009     workers()->set_active_workers(active_workers);
4010 
4011     double pause_start_sec = os::elapsedTime();
4012     g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4013     log_gc_header();
4014 
4015     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4016     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4017 
4018     // If the secondary_free_list is not empty, append it to the
4019     // free_list. No need to wait for the cleanup operation to finish;
4020     // the region allocation code will check the secondary_free_list
4021     // and wait if necessary. If the G1StressConcRegionFreeing flag is
4022     // set, skip this step so that the region allocation code has to
4023     // get entries from the secondary_free_list.
4024     if (!G1StressConcRegionFreeing) {
4025       append_secondary_free_list_if_not_empty_with_lock();
4026     }
4027 
4028     assert(check_young_list_well_formed(), "young list should be well formed");
4029 
4030     // Don't dynamically change the number of GC threads this early.  A value of
4031     // 0 is used to indicate serial work.  When parallel work is done,
4032     // it will be set.
4033 
4034     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4035       IsGCActiveMark x;
4036 
4037       gc_prologue(false);
4038       increment_total_collections(false /* full gc */);
4039       increment_gc_time_stamp();
4040 
4041       verify_before_gc();
4042 
4043       check_bitmaps("GC Start");
4044 
4045 #if defined(COMPILER2) || INCLUDE_JVMCI
4046       DerivedPointerTable::clear();
4047 #endif
4048 
4049       // Please see comment in g1CollectedHeap.hpp and
4050       // G1CollectedHeap::ref_processing_init() to see how
4051       // reference processing currently works in G1.
4052 
4053       // Enable discovery in the STW reference processor
4054       ref_processor_stw()->enable_discovery();
4055 
4056       {
4057         // We want to temporarily turn off discovery by the
4058         // CM ref processor, if necessary, and turn it back on
4059         // on again later if we do. Using a scoped
4060         // NoRefDiscovery object will do this.
4061         NoRefDiscovery no_cm_discovery(ref_processor_cm());
4062 
4063         // Forget the current alloc region (we might even choose it to be part
4064         // of the collection set!).
4065         _allocator->release_mutator_alloc_region();
4066 
4067         // We should call this after we retire the mutator alloc
4068         // region(s) so that all the ALLOC / RETIRE events are generated
4069         // before the start GC event.
4070         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4071 
4072         // This timing is only used by the ergonomics to handle our pause target.
4073         // It is unclear why this should not include the full pause. We will
4074         // investigate this in CR 7178365.
4075         //
4076         // Preserving the old comment here if that helps the investigation:
4077         //
4078         // The elapsed time induced by the start time below deliberately elides
4079         // the possible verification above.
4080         double sample_start_time_sec = os::elapsedTime();
4081 
4082         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4083 
4084         if (collector_state()->during_initial_mark_pause()) {
4085           concurrent_mark()->checkpointRootsInitialPre();
4086         }
4087 
4088         double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
4089         g1_policy()->finalize_old_cset_part(time_remaining_ms);
4090 
4091         evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
4092 
4093         register_humongous_regions_with_cset();
4094 
4095         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4096 
4097         _cm->note_start_of_gc();
4098         // We call this after finalize_cset() to
4099         // ensure that the CSet has been finalized.
4100         _cm->verify_no_cset_oops();
4101 
4102         if (_hr_printer.is_active()) {
4103           HeapRegion* hr = g1_policy()->collection_set();
4104           while (hr != NULL) {
4105             _hr_printer.cset(hr);
4106             hr = hr->next_in_collection_set();
4107           }
4108         }
4109 
4110 #ifdef ASSERT
4111         VerifyCSetClosure cl;
4112         collection_set_iterate(&cl);
4113 #endif // ASSERT
4114 
4115         // Initialize the GC alloc regions.
4116         _allocator->init_gc_alloc_regions(evacuation_info);
4117 
4118         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
4119         // Actually do the work...
4120         evacuate_collection_set(evacuation_info, &per_thread_states);
4121 
4122         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
4123         free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
4124 
4125         eagerly_reclaim_humongous_regions();
4126 
4127         g1_policy()->clear_collection_set();
4128 
4129         // Start a new incremental collection set for the next pause.
4130         g1_policy()->start_incremental_cset_building();
4131 
4132         clear_cset_fast_test();
4133 
4134         _young_list->reset_sampled_info();
4135 
4136         // Don't check the whole heap at this point as the
4137         // GC alloc regions from this pause have been tagged
4138         // as survivors and moved on to the survivor list.
4139         // Survivor regions will fail the !is_young() check.
4140         assert(check_young_list_empty(false /* check_heap */),
4141           "young list should be empty");
4142 
4143         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4144                                              _young_list->first_survivor_region(),
4145                                              _young_list->last_survivor_region());
4146 
4147         _young_list->reset_auxilary_lists();
4148 
4149         if (evacuation_failed()) {
4150           set_used(recalculate_used());
4151           if (_archive_allocator != NULL) {
4152             _archive_allocator->clear_used();
4153           }
4154           for (uint i = 0; i < ParallelGCThreads; i++) {
4155             if (_evacuation_failed_info_array[i].has_failed()) {
4156               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4157             }
4158           }
4159         } else {
4160           // The "used" of the the collection set have already been subtracted
4161           // when they were freed.  Add in the bytes evacuated.
4162           increase_used(g1_policy()->bytes_copied_during_gc());
4163         }
4164 
4165         if (collector_state()->during_initial_mark_pause()) {
4166           // We have to do this before we notify the CM threads that
4167           // they can start working to make sure that all the
4168           // appropriate initialization is done on the CM object.
4169           concurrent_mark()->checkpointRootsInitialPost();
4170           collector_state()->set_mark_in_progress(true);
4171           // Note that we don't actually trigger the CM thread at
4172           // this point. We do that later when we're sure that
4173           // the current thread has completed its logging output.
4174         }
4175 
4176         allocate_dummy_regions();
4177 
4178         _allocator->init_mutator_alloc_region();
4179 
4180         {
4181           size_t expand_bytes = g1_policy()->expansion_amount();
4182           if (expand_bytes > 0) {
4183             size_t bytes_before = capacity();
4184             // No need for an ergo verbose message here,
4185             // expansion_amount() does this when it returns a value > 0.
4186             if (!expand(expand_bytes)) {
4187               // We failed to expand the heap. Cannot do anything about it.
4188             }
4189           }
4190         }
4191 
4192         // We redo the verification but now wrt to the new CSet which
4193         // has just got initialized after the previous CSet was freed.
4194         _cm->verify_no_cset_oops();
4195         _cm->note_end_of_gc();
4196 
4197         // This timing is only used by the ergonomics to handle our pause target.
4198         // It is unclear why this should not include the full pause. We will
4199         // investigate this in CR 7178365.
4200         double sample_end_time_sec = os::elapsedTime();
4201         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4202         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4203         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4204 
4205         evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4206         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4207 
4208         MemoryService::track_memory_usage();
4209 
4210         // In prepare_for_verify() below we'll need to scan the deferred
4211         // update buffers to bring the RSets up-to-date if
4212         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4213         // the update buffers we'll probably need to scan cards on the
4214         // regions we just allocated to (i.e., the GC alloc
4215         // regions). However, during the last GC we called
4216         // set_saved_mark() on all the GC alloc regions, so card
4217         // scanning might skip the [saved_mark_word()...top()] area of
4218         // those regions (i.e., the area we allocated objects into
4219         // during the last GC). But it shouldn't. Given that
4220         // saved_mark_word() is conditional on whether the GC time stamp
4221         // on the region is current or not, by incrementing the GC time
4222         // stamp here we invalidate all the GC time stamps on all the
4223         // regions and saved_mark_word() will simply return top() for
4224         // all the regions. This is a nicer way of ensuring this rather
4225         // than iterating over the regions and fixing them. In fact, the
4226         // GC time stamp increment here also ensures that
4227         // saved_mark_word() will return top() between pauses, i.e.,
4228         // during concurrent refinement. So we don't need the
4229         // is_gc_active() check to decided which top to use when
4230         // scanning cards (see CR 7039627).
4231         increment_gc_time_stamp();
4232 
4233         verify_after_gc();
4234         check_bitmaps("GC End");
4235 
4236         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4237         ref_processor_stw()->verify_no_references_recorded();
4238 
4239         // CM reference discovery will be re-enabled if necessary.
4240       }
4241 
4242       // We should do this after we potentially expand the heap so
4243       // that all the COMMIT events are generated before the end GC
4244       // event, and after we retire the GC alloc regions so that all
4245       // RETIRE events are generated before the end GC event.
4246       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4247 
4248 #ifdef TRACESPINNING
4249       ParallelTaskTerminator::print_termination_counts();
4250 #endif
4251 
4252       gc_epilogue(false);
4253     }
4254 
4255     // Print the remainder of the GC log output.
4256     log_gc_footer(os::elapsedTime() - pause_start_sec);
4257 
4258     // It is not yet to safe to tell the concurrent mark to
4259     // start as we have some optional output below. We don't want the
4260     // output from the concurrent mark thread interfering with this
4261     // logging output either.
4262 
4263     _hrm.verify_optional();
4264     verify_region_sets_optional();
4265 
4266     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4267     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4268 
4269     print_heap_after_gc();
4270     trace_heap_after_gc(_gc_tracer_stw);
4271 
4272     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4273     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4274     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4275     // before any GC notifications are raised.
4276     g1mm()->update_sizes();
4277 
4278     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4279     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4280     _gc_timer_stw->register_gc_end();
4281     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4282   }
4283   // It should now be safe to tell the concurrent mark thread to start
4284   // without its logging output interfering with the logging output
4285   // that came from the pause.
4286 
4287   if (should_start_conc_mark) {
4288     // CAUTION: after the doConcurrentMark() call below,
4289     // the concurrent marking thread(s) could be running
4290     // concurrently with us. Make sure that anything after
4291     // this point does not assume that we are the only GC thread
4292     // running. Note: of course, the actual marking work will
4293     // not start until the safepoint itself is released in
4294     // SuspendibleThreadSet::desynchronize().
4295     doConcurrentMark();
4296   }
4297 
4298   return true;
4299 }
4300 
4301 void G1CollectedHeap::remove_self_forwarding_pointers() {
4302   double remove_self_forwards_start = os::elapsedTime();
4303 
4304   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4305   workers()->run_task(&rsfp_task);
4306 
4307   // Now restore saved marks, if any.
4308   for (uint i = 0; i < ParallelGCThreads; i++) {
4309     OopAndMarkOopStack& cur = _preserved_objs[i];
4310     while (!cur.is_empty()) {
4311       OopAndMarkOop elem = cur.pop();
4312       elem.set_mark();
4313     }
4314     cur.clear(true);
4315   }
4316 
4317   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4318 }
4319 
4320 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4321   if (!_evacuation_failed) {
4322     _evacuation_failed = true;
4323   }
4324 
4325   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4326 
4327   // We want to call the "for_promotion_failure" version only in the
4328   // case of a promotion failure.
4329   if (m->must_be_preserved_for_promotion_failure(obj)) {
4330     OopAndMarkOop elem(obj, m);
4331     _preserved_objs[worker_id].push(elem);
4332   }
4333 }
4334 
4335 void G1ParCopyHelper::mark_object(oop obj) {
4336   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4337 
4338   // We know that the object is not moving so it's safe to read its size.
4339   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4340 }
4341 
4342 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4343   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4344   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4345   assert(from_obj != to_obj, "should not be self-forwarded");
4346 
4347   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4348   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4349 
4350   // The object might be in the process of being copied by another
4351   // worker so we cannot trust that its to-space image is
4352   // well-formed. So we have to read its size from its from-space
4353   // image which we know should not be changing.
4354   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4355 }
4356 
4357 template <class T>
4358 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4359   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4360     _scanned_klass->record_modified_oops();
4361   }
4362 }
4363 
4364 template <G1Barrier barrier, G1Mark do_mark_object>
4365 template <class T>
4366 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4367   T heap_oop = oopDesc::load_heap_oop(p);
4368 
4369   if (oopDesc::is_null(heap_oop)) {
4370     return;
4371   }
4372 
4373   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4374 
4375   assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4376 
4377   const InCSetState state = _g1->in_cset_state(obj);
4378   if (state.is_in_cset()) {
4379     oop forwardee;
4380     markOop m = obj->mark();
4381     if (m->is_marked()) {
4382       forwardee = (oop) m->decode_pointer();
4383     } else {
4384       forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4385     }
4386     assert(forwardee != NULL, "forwardee should not be NULL");
4387     oopDesc::encode_store_heap_oop(p, forwardee);
4388     if (do_mark_object != G1MarkNone && forwardee != obj) {
4389       // If the object is self-forwarded we don't need to explicitly
4390       // mark it, the evacuation failure protocol will do so.
4391       mark_forwarded_object(obj, forwardee);
4392     }
4393 
4394     if (barrier == G1BarrierKlass) {
4395       do_klass_barrier(p, forwardee);
4396     }
4397   } else {
4398     if (state.is_humongous()) {
4399       _g1->set_humongous_is_live(obj);
4400     }
4401     // The object is not in collection set. If we're a root scanning
4402     // closure during an initial mark pause then attempt to mark the object.
4403     if (do_mark_object == G1MarkFromRoot) {
4404       mark_object(obj);
4405     }
4406   }
4407 }
4408 
4409 class G1ParEvacuateFollowersClosure : public VoidClosure {
4410 private:
4411   double _start_term;
4412   double _term_time;
4413   size_t _term_attempts;
4414 
4415   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4416   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4417 protected:
4418   G1CollectedHeap*              _g1h;
4419   G1ParScanThreadState*         _par_scan_state;
4420   RefToScanQueueSet*            _queues;
4421   ParallelTaskTerminator*       _terminator;
4422 
4423   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4424   RefToScanQueueSet*      queues()         { return _queues; }
4425   ParallelTaskTerminator* terminator()     { return _terminator; }
4426 
4427 public:
4428   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4429                                 G1ParScanThreadState* par_scan_state,
4430                                 RefToScanQueueSet* queues,
4431                                 ParallelTaskTerminator* terminator)
4432     : _g1h(g1h), _par_scan_state(par_scan_state),
4433       _queues(queues), _terminator(terminator),
4434       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4435 
4436   void do_void();
4437 
4438   double term_time() const { return _term_time; }
4439   size_t term_attempts() const { return _term_attempts; }
4440 
4441 private:
4442   inline bool offer_termination();
4443 };
4444 
4445 bool G1ParEvacuateFollowersClosure::offer_termination() {
4446   G1ParScanThreadState* const pss = par_scan_state();
4447   start_term_time();
4448   const bool res = terminator()->offer_termination();
4449   end_term_time();
4450   return res;
4451 }
4452 
4453 void G1ParEvacuateFollowersClosure::do_void() {
4454   G1ParScanThreadState* const pss = par_scan_state();
4455   pss->trim_queue();
4456   do {
4457     pss->steal_and_trim_queue(queues());
4458   } while (!offer_termination());
4459 }
4460 
4461 class G1KlassScanClosure : public KlassClosure {
4462  G1ParCopyHelper* _closure;
4463  bool             _process_only_dirty;
4464  int              _count;
4465  public:
4466   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4467       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4468   void do_klass(Klass* klass) {
4469     // If the klass has not been dirtied we know that there's
4470     // no references into  the young gen and we can skip it.
4471    if (!_process_only_dirty || klass->has_modified_oops()) {
4472       // Clean the klass since we're going to scavenge all the metadata.
4473       klass->clear_modified_oops();
4474 
4475       // Tell the closure that this klass is the Klass to scavenge
4476       // and is the one to dirty if oops are left pointing into the young gen.
4477       _closure->set_scanned_klass(klass);
4478 
4479       klass->oops_do(_closure);
4480 
4481       _closure->set_scanned_klass(NULL);
4482     }
4483     _count++;
4484   }
4485 };
4486 
4487 class G1ParTask : public AbstractGangTask {
4488 protected:
4489   G1CollectedHeap*         _g1h;
4490   G1ParScanThreadStateSet* _pss;
4491   RefToScanQueueSet*       _queues;
4492   G1RootProcessor*         _root_processor;
4493   ParallelTaskTerminator   _terminator;
4494   uint                     _n_workers;
4495 
4496 public:
4497   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4498     : AbstractGangTask("G1 collection"),
4499       _g1h(g1h),
4500       _pss(per_thread_states),
4501       _queues(task_queues),
4502       _root_processor(root_processor),
4503       _terminator(n_workers, _queues),
4504       _n_workers(n_workers)
4505   {}
4506 
4507   RefToScanQueueSet* queues() { return _queues; }
4508 
4509   RefToScanQueue *work_queue(int i) {
4510     return queues()->queue(i);
4511   }
4512 
4513   ParallelTaskTerminator* terminator() { return &_terminator; }
4514 
4515   // Helps out with CLD processing.
4516   //
4517   // During InitialMark we need to:
4518   // 1) Scavenge all CLDs for the young GC.
4519   // 2) Mark all objects directly reachable from strong CLDs.
4520   template <G1Mark do_mark_object>
4521   class G1CLDClosure : public CLDClosure {
4522     G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
4523     G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
4524     G1KlassScanClosure                                _klass_in_cld_closure;
4525     bool                                              _claim;
4526 
4527    public:
4528     G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4529                  bool only_young, bool claim)
4530         : _oop_closure(oop_closure),
4531           _oop_in_klass_closure(oop_closure->g1(),
4532                                 oop_closure->pss()),
4533           _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4534           _claim(claim) {
4535 
4536     }
4537 
4538     void do_cld(ClassLoaderData* cld) {
4539       cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4540     }
4541   };
4542 
4543   void work(uint worker_id) {
4544     if (worker_id >= _n_workers) return;  // no work needed this round
4545 
4546     double start_sec = os::elapsedTime();
4547     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4548 
4549     {
4550       ResourceMark rm;
4551       HandleMark   hm;
4552 
4553       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4554 
4555       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
4556       pss->set_ref_processor(rp);
4557 
4558       bool only_young = _g1h->collector_state()->gcs_are_young();
4559 
4560       // Non-IM young GC.
4561       G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, pss);
4562       G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
4563                                                                                only_young, // Only process dirty klasses.
4564                                                                                false);     // No need to claim CLDs.
4565       // IM young GC.
4566       //    Strong roots closures.
4567       G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, pss);
4568       G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
4569                                                                                false, // Process all klasses.
4570                                                                                true); // Need to claim CLDs.
4571       //    Weak roots closures.
4572       G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss);
4573       G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4574                                                                                     false, // Process all klasses.
4575                                                                                     true); // Need to claim CLDs.
4576 
4577       OopClosure* strong_root_cl;
4578       OopClosure* weak_root_cl;
4579       CLDClosure* strong_cld_cl;
4580       CLDClosure* weak_cld_cl;
4581 
4582       bool trace_metadata = false;
4583 
4584       if (_g1h->collector_state()->during_initial_mark_pause()) {
4585         // We also need to mark copied objects.
4586         strong_root_cl = &scan_mark_root_cl;
4587         strong_cld_cl  = &scan_mark_cld_cl;
4588         if (ClassUnloadingWithConcurrentMark) {
4589           weak_root_cl = &scan_mark_weak_root_cl;
4590           weak_cld_cl  = &scan_mark_weak_cld_cl;
4591           trace_metadata = true;
4592         } else {
4593           weak_root_cl = &scan_mark_root_cl;
4594           weak_cld_cl  = &scan_mark_cld_cl;
4595         }
4596       } else {
4597         strong_root_cl = &scan_only_root_cl;
4598         weak_root_cl   = &scan_only_root_cl;
4599         strong_cld_cl  = &scan_only_cld_cl;
4600         weak_cld_cl    = &scan_only_cld_cl;
4601       }
4602 
4603       double start_strong_roots_sec = os::elapsedTime();
4604       _root_processor->evacuate_roots(strong_root_cl,
4605                                       weak_root_cl,
4606                                       strong_cld_cl,
4607                                       weak_cld_cl,
4608                                       trace_metadata,
4609                                       worker_id);
4610 
4611       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4612       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4613                                                                              weak_root_cl,
4614                                                                              worker_id);
4615 
4616       _pss->add_cards_scanned(worker_id, cards_scanned);
4617 
4618       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4619 
4620       double term_sec = 0.0;
4621       size_t evac_term_attempts = 0;
4622       {
4623         double start = os::elapsedTime();
4624         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4625         evac.do_void();
4626 
4627         evac_term_attempts = evac.term_attempts();
4628         term_sec = evac.term_time();
4629         double elapsed_sec = os::elapsedTime() - start;
4630         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4631         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4632         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4633       }
4634 
4635       assert(pss->queue_is_empty(), "should be empty");
4636 
4637       if (PrintTerminationStats) {
4638         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4639         size_t lab_waste;
4640         size_t lab_undo_waste;
4641         pss->waste(lab_waste, lab_undo_waste);
4642         _g1h->print_termination_stats(gclog_or_tty,
4643                                       worker_id,
4644                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
4645                                       strong_roots_sec * 1000.0,                  /* strong roots time */
4646                                       term_sec * 1000.0,                          /* evac term time */
4647                                       evac_term_attempts,                         /* evac term attempts */
4648                                       lab_waste,                                  /* alloc buffer waste */
4649                                       lab_undo_waste                              /* undo waste */
4650                                       );
4651       }
4652 
4653       // Close the inner scope so that the ResourceMark and HandleMark
4654       // destructors are executed here and are included as part of the
4655       // "GC Worker Time".
4656     }
4657     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4658   }
4659 };
4660 
4661 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4662   st->print_raw_cr("GC Termination Stats");
4663   st->print_raw_cr("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
4664   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts  total   alloc    undo");
4665   st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4666 }
4667 
4668 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4669                                               uint worker_id,
4670                                               double elapsed_ms,
4671                                               double strong_roots_ms,
4672                                               double term_ms,
4673                                               size_t term_attempts,
4674                                               size_t alloc_buffer_waste,
4675                                               size_t undo_waste) const {
4676   st->print_cr("%3d %9.2f %9.2f %6.2f "
4677                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4678                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4679                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4680                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4681                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4682                alloc_buffer_waste * HeapWordSize / K,
4683                undo_waste * HeapWordSize / K);
4684 }
4685 
4686 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4687 private:
4688   BoolObjectClosure* _is_alive;
4689   int _initial_string_table_size;
4690   int _initial_symbol_table_size;
4691 
4692   bool  _process_strings;
4693   int _strings_processed;
4694   int _strings_removed;
4695 
4696   bool  _process_symbols;
4697   int _symbols_processed;
4698   int _symbols_removed;
4699 
4700 public:
4701   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4702     AbstractGangTask("String/Symbol Unlinking"),
4703     _is_alive(is_alive),
4704     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4705     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4706 
4707     _initial_string_table_size = StringTable::the_table()->table_size();
4708     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4709     if (process_strings) {
4710       StringTable::clear_parallel_claimed_index();
4711     }
4712     if (process_symbols) {
4713       SymbolTable::clear_parallel_claimed_index();
4714     }
4715   }
4716 
4717   ~G1StringSymbolTableUnlinkTask() {
4718     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4719               err_msg("claim value %d after unlink less than initial string table size %d",
4720                       StringTable::parallel_claimed_index(), _initial_string_table_size));
4721     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4722               err_msg("claim value %d after unlink less than initial symbol table size %d",
4723                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4724 
4725     if (G1TraceStringSymbolTableScrubbing) {
4726       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4727                              "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4728                              "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4729                              strings_processed(), strings_removed(),
4730                              symbols_processed(), symbols_removed());
4731     }
4732   }
4733 
4734   void work(uint worker_id) {
4735     int strings_processed = 0;
4736     int strings_removed = 0;
4737     int symbols_processed = 0;
4738     int symbols_removed = 0;
4739     if (_process_strings) {
4740       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4741       Atomic::add(strings_processed, &_strings_processed);
4742       Atomic::add(strings_removed, &_strings_removed);
4743     }
4744     if (_process_symbols) {
4745       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4746       Atomic::add(symbols_processed, &_symbols_processed);
4747       Atomic::add(symbols_removed, &_symbols_removed);
4748     }
4749   }
4750 
4751   size_t strings_processed() const { return (size_t)_strings_processed; }
4752   size_t strings_removed()   const { return (size_t)_strings_removed; }
4753 
4754   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4755   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4756 };
4757 
4758 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4759 private:
4760   static Monitor* _lock;
4761 
4762   BoolObjectClosure* const _is_alive;
4763   const bool               _unloading_occurred;
4764   const uint               _num_workers;
4765 
4766   // Variables used to claim nmethods.
4767   nmethod* _first_nmethod;
4768   volatile nmethod* _claimed_nmethod;
4769 
4770   // The list of nmethods that need to be processed by the second pass.
4771   volatile nmethod* _postponed_list;
4772   volatile uint     _num_entered_barrier;
4773 
4774  public:
4775   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4776       _is_alive(is_alive),
4777       _unloading_occurred(unloading_occurred),
4778       _num_workers(num_workers),
4779       _first_nmethod(NULL),
4780       _claimed_nmethod(NULL),
4781       _postponed_list(NULL),
4782       _num_entered_barrier(0)
4783   {
4784     nmethod::increase_unloading_clock();
4785     // Get first alive nmethod
4786     NMethodIterator iter = NMethodIterator();
4787     if(iter.next_alive()) {
4788       _first_nmethod = iter.method();
4789     }
4790     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4791   }
4792 
4793   ~G1CodeCacheUnloadingTask() {
4794     CodeCache::verify_clean_inline_caches();
4795 
4796     CodeCache::set_needs_cache_clean(false);
4797     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4798 
4799     CodeCache::verify_icholder_relocations();
4800   }
4801 
4802  private:
4803   void add_to_postponed_list(nmethod* nm) {
4804       nmethod* old;
4805       do {
4806         old = (nmethod*)_postponed_list;
4807         nm->set_unloading_next(old);
4808       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4809   }
4810 
4811   void clean_nmethod(nmethod* nm) {
4812     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4813 
4814     if (postponed) {
4815       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4816       add_to_postponed_list(nm);
4817     }
4818 
4819     // Mark that this thread has been cleaned/unloaded.
4820     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4821     nm->set_unloading_clock(nmethod::global_unloading_clock());
4822   }
4823 
4824   void clean_nmethod_postponed(nmethod* nm) {
4825     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4826   }
4827 
4828   static const int MaxClaimNmethods = 16;
4829 
4830   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4831     nmethod* first;
4832     NMethodIterator last;
4833 
4834     do {
4835       *num_claimed_nmethods = 0;
4836 
4837       first = (nmethod*)_claimed_nmethod;
4838       last = NMethodIterator(first);
4839 
4840       if (first != NULL) {
4841 
4842         for (int i = 0; i < MaxClaimNmethods; i++) {
4843           if (!last.next_alive()) {
4844             break;
4845           }
4846           claimed_nmethods[i] = last.method();
4847           (*num_claimed_nmethods)++;
4848         }
4849       }
4850 
4851     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4852   }
4853 
4854   nmethod* claim_postponed_nmethod() {
4855     nmethod* claim;
4856     nmethod* next;
4857 
4858     do {
4859       claim = (nmethod*)_postponed_list;
4860       if (claim == NULL) {
4861         return NULL;
4862       }
4863 
4864       next = claim->unloading_next();
4865 
4866     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4867 
4868     return claim;
4869   }
4870 
4871  public:
4872   // Mark that we're done with the first pass of nmethod cleaning.
4873   void barrier_mark(uint worker_id) {
4874     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4875     _num_entered_barrier++;
4876     if (_num_entered_barrier == _num_workers) {
4877       ml.notify_all();
4878     }
4879   }
4880 
4881   // See if we have to wait for the other workers to
4882   // finish their first-pass nmethod cleaning work.
4883   void barrier_wait(uint worker_id) {
4884     if (_num_entered_barrier < _num_workers) {
4885       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4886       while (_num_entered_barrier < _num_workers) {
4887           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4888       }
4889     }
4890   }
4891 
4892   // Cleaning and unloading of nmethods. Some work has to be postponed
4893   // to the second pass, when we know which nmethods survive.
4894   void work_first_pass(uint worker_id) {
4895     // The first nmethods is claimed by the first worker.
4896     if (worker_id == 0 && _first_nmethod != NULL) {
4897       clean_nmethod(_first_nmethod);
4898       _first_nmethod = NULL;
4899     }
4900 
4901     int num_claimed_nmethods;
4902     nmethod* claimed_nmethods[MaxClaimNmethods];
4903 
4904     while (true) {
4905       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4906 
4907       if (num_claimed_nmethods == 0) {
4908         break;
4909       }
4910 
4911       for (int i = 0; i < num_claimed_nmethods; i++) {
4912         clean_nmethod(claimed_nmethods[i]);
4913       }
4914     }
4915   }
4916 
4917   void work_second_pass(uint worker_id) {
4918     nmethod* nm;
4919     // Take care of postponed nmethods.
4920     while ((nm = claim_postponed_nmethod()) != NULL) {
4921       clean_nmethod_postponed(nm);
4922     }
4923   }
4924 };
4925 
4926 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4927 
4928 class G1KlassCleaningTask : public StackObj {
4929   BoolObjectClosure*                      _is_alive;
4930   volatile jint                           _clean_klass_tree_claimed;
4931   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4932 
4933  public:
4934   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4935       _is_alive(is_alive),
4936       _clean_klass_tree_claimed(0),
4937       _klass_iterator() {
4938   }
4939 
4940  private:
4941   bool claim_clean_klass_tree_task() {
4942     if (_clean_klass_tree_claimed) {
4943       return false;
4944     }
4945 
4946     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4947   }
4948 
4949   InstanceKlass* claim_next_klass() {
4950     Klass* klass;
4951     do {
4952       klass =_klass_iterator.next_klass();
4953     } while (klass != NULL && !klass->oop_is_instance());
4954 
4955     return (InstanceKlass*)klass;
4956   }
4957 
4958 public:
4959 
4960   void clean_klass(InstanceKlass* ik) {
4961     ik->clean_implementors_list(_is_alive);
4962     ik->clean_method_data(_is_alive);
4963 
4964     // G1 specific cleanup work that has
4965     // been moved here to be done in parallel.
4966     ik->clean_dependent_nmethods();
4967   }
4968 
4969   void work() {
4970     ResourceMark rm;
4971 
4972     // One worker will clean the subklass/sibling klass tree.
4973     if (claim_clean_klass_tree_task()) {
4974       Klass::clean_subklass_tree(_is_alive);
4975     }
4976 
4977     // All workers will help cleaning the classes,
4978     InstanceKlass* klass;
4979     while ((klass = claim_next_klass()) != NULL) {
4980       clean_klass(klass);
4981     }
4982   }
4983 };
4984 
4985 // To minimize the remark pause times, the tasks below are done in parallel.
4986 class G1ParallelCleaningTask : public AbstractGangTask {
4987 private:
4988   G1StringSymbolTableUnlinkTask _string_symbol_task;
4989   G1CodeCacheUnloadingTask      _code_cache_task;
4990   G1KlassCleaningTask           _klass_cleaning_task;
4991 
4992 public:
4993   // The constructor is run in the VMThread.
4994   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4995       AbstractGangTask("Parallel Cleaning"),
4996       _string_symbol_task(is_alive, process_strings, process_symbols),
4997       _code_cache_task(num_workers, is_alive, unloading_occurred),
4998       _klass_cleaning_task(is_alive) {
4999   }
5000 
5001   // The parallel work done by all worker threads.
5002   void work(uint worker_id) {
5003     // Do first pass of code cache cleaning.
5004     _code_cache_task.work_first_pass(worker_id);
5005 
5006     // Let the threads mark that the first pass is done.
5007     _code_cache_task.barrier_mark(worker_id);
5008 
5009     // Clean the Strings and Symbols.
5010     _string_symbol_task.work(worker_id);
5011 
5012     // Wait for all workers to finish the first code cache cleaning pass.
5013     _code_cache_task.barrier_wait(worker_id);
5014 
5015     // Do the second code cache cleaning work, which realize on
5016     // the liveness information gathered during the first pass.
5017     _code_cache_task.work_second_pass(worker_id);
5018 
5019     // Clean all klasses that were not unloaded.
5020     _klass_cleaning_task.work();
5021   }
5022 };
5023 
5024 
5025 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5026                                         bool process_strings,
5027                                         bool process_symbols,
5028                                         bool class_unloading_occurred) {
5029   uint n_workers = workers()->active_workers();
5030 
5031   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5032                                         n_workers, class_unloading_occurred);
5033   workers()->run_task(&g1_unlink_task);
5034 }
5035 
5036 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5037                                                      bool process_strings, bool process_symbols) {
5038   {
5039     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5040     workers()->run_task(&g1_unlink_task);
5041   }
5042 
5043   if (G1StringDedup::is_enabled()) {
5044     G1StringDedup::unlink(is_alive);
5045   }
5046 }
5047 
5048 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5049  private:
5050   DirtyCardQueueSet* _queue;
5051  public:
5052   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5053 
5054   virtual void work(uint worker_id) {
5055     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5056     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5057 
5058     RedirtyLoggedCardTableEntryClosure cl;
5059     _queue->par_apply_closure_to_all_completed_buffers(&cl);
5060 
5061     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5062   }
5063 };
5064 
5065 void G1CollectedHeap::redirty_logged_cards() {
5066   double redirty_logged_cards_start = os::elapsedTime();
5067 
5068   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5069   dirty_card_queue_set().reset_for_par_iteration();
5070   workers()->run_task(&redirty_task);
5071 
5072   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5073   dcq.merge_bufferlists(&dirty_card_queue_set());
5074   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5075 
5076   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5077 }
5078 
5079 // Weak Reference Processing support
5080 
5081 // An always "is_alive" closure that is used to preserve referents.
5082 // If the object is non-null then it's alive.  Used in the preservation
5083 // of referent objects that are pointed to by reference objects
5084 // discovered by the CM ref processor.
5085 class G1AlwaysAliveClosure: public BoolObjectClosure {
5086   G1CollectedHeap* _g1;
5087 public:
5088   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5089   bool do_object_b(oop p) {
5090     if (p != NULL) {
5091       return true;
5092     }
5093     return false;
5094   }
5095 };
5096 
5097 bool G1STWIsAliveClosure::do_object_b(oop p) {
5098   // An object is reachable if it is outside the collection set,
5099   // or is inside and copied.
5100   return !_g1->is_in_cset(p) || p->is_forwarded();
5101 }
5102 
5103 // Non Copying Keep Alive closure
5104 class G1KeepAliveClosure: public OopClosure {
5105   G1CollectedHeap* _g1;
5106 public:
5107   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5108   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5109   void do_oop(oop* p) {
5110     oop obj = *p;
5111     assert(obj != NULL, "the caller should have filtered out NULL values");
5112 
5113     const InCSetState cset_state = _g1->in_cset_state(obj);
5114     if (!cset_state.is_in_cset_or_humongous()) {
5115       return;
5116     }
5117     if (cset_state.is_in_cset()) {
5118       assert( obj->is_forwarded(), "invariant" );
5119       *p = obj->forwardee();
5120     } else {
5121       assert(!obj->is_forwarded(), "invariant" );
5122       assert(cset_state.is_humongous(),
5123              err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5124       _g1->set_humongous_is_live(obj);
5125     }
5126   }
5127 };
5128 
5129 // Copying Keep Alive closure - can be called from both
5130 // serial and parallel code as long as different worker
5131 // threads utilize different G1ParScanThreadState instances
5132 // and different queues.
5133 
5134 class G1CopyingKeepAliveClosure: public OopClosure {
5135   G1CollectedHeap*         _g1h;
5136   OopClosure*              _copy_non_heap_obj_cl;
5137   G1ParScanThreadState*    _par_scan_state;
5138 
5139 public:
5140   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5141                             OopClosure* non_heap_obj_cl,
5142                             G1ParScanThreadState* pss):
5143     _g1h(g1h),
5144     _copy_non_heap_obj_cl(non_heap_obj_cl),
5145     _par_scan_state(pss)
5146   {}
5147 
5148   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5149   virtual void do_oop(      oop* p) { do_oop_work(p); }
5150 
5151   template <class T> void do_oop_work(T* p) {
5152     oop obj = oopDesc::load_decode_heap_oop(p);
5153 
5154     if (_g1h->is_in_cset_or_humongous(obj)) {
5155       // If the referent object has been forwarded (either copied
5156       // to a new location or to itself in the event of an
5157       // evacuation failure) then we need to update the reference
5158       // field and, if both reference and referent are in the G1
5159       // heap, update the RSet for the referent.
5160       //
5161       // If the referent has not been forwarded then we have to keep
5162       // it alive by policy. Therefore we have copy the referent.
5163       //
5164       // If the reference field is in the G1 heap then we can push
5165       // on the PSS queue. When the queue is drained (after each
5166       // phase of reference processing) the object and it's followers
5167       // will be copied, the reference field set to point to the
5168       // new location, and the RSet updated. Otherwise we need to
5169       // use the the non-heap or metadata closures directly to copy
5170       // the referent object and update the pointer, while avoiding
5171       // updating the RSet.
5172 
5173       if (_g1h->is_in_g1_reserved(p)) {
5174         _par_scan_state->push_on_queue(p);
5175       } else {
5176         assert(!Metaspace::contains((const void*)p),
5177                err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5178         _copy_non_heap_obj_cl->do_oop(p);
5179       }
5180     }
5181   }
5182 };
5183 
5184 // Serial drain queue closure. Called as the 'complete_gc'
5185 // closure for each discovered list in some of the
5186 // reference processing phases.
5187 
5188 class G1STWDrainQueueClosure: public VoidClosure {
5189 protected:
5190   G1CollectedHeap* _g1h;
5191   G1ParScanThreadState* _par_scan_state;
5192 
5193   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5194 
5195 public:
5196   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5197     _g1h(g1h),
5198     _par_scan_state(pss)
5199   { }
5200 
5201   void do_void() {
5202     G1ParScanThreadState* const pss = par_scan_state();
5203     pss->trim_queue();
5204   }
5205 };
5206 
5207 // Parallel Reference Processing closures
5208 
5209 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5210 // processing during G1 evacuation pauses.
5211 
5212 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5213 private:
5214   G1CollectedHeap*          _g1h;
5215   G1ParScanThreadStateSet*  _pss;
5216   RefToScanQueueSet*        _queues;
5217   WorkGang*                 _workers;
5218   uint                      _active_workers;
5219 
5220 public:
5221   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5222                            G1ParScanThreadStateSet* per_thread_states,
5223                            WorkGang* workers,
5224                            RefToScanQueueSet *task_queues,
5225                            uint n_workers) :
5226     _g1h(g1h),
5227     _pss(per_thread_states),
5228     _queues(task_queues),
5229     _workers(workers),
5230     _active_workers(n_workers)
5231   {
5232     assert(n_workers > 0, "shouldn't call this otherwise");
5233   }
5234 
5235   // Executes the given task using concurrent marking worker threads.
5236   virtual void execute(ProcessTask& task);
5237   virtual void execute(EnqueueTask& task);
5238 };
5239 
5240 // Gang task for possibly parallel reference processing
5241 
5242 class G1STWRefProcTaskProxy: public AbstractGangTask {
5243   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5244   ProcessTask&     _proc_task;
5245   G1CollectedHeap* _g1h;
5246   G1ParScanThreadStateSet* _pss;
5247   RefToScanQueueSet* _task_queues;
5248   ParallelTaskTerminator* _terminator;
5249 
5250 public:
5251   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5252                         G1CollectedHeap* g1h,
5253                         G1ParScanThreadStateSet* per_thread_states,
5254                         RefToScanQueueSet *task_queues,
5255                         ParallelTaskTerminator* terminator) :
5256     AbstractGangTask("Process reference objects in parallel"),
5257     _proc_task(proc_task),
5258     _g1h(g1h),
5259     _pss(per_thread_states),
5260     _task_queues(task_queues),
5261     _terminator(terminator)
5262   {}
5263 
5264   virtual void work(uint worker_id) {
5265     // The reference processing task executed by a single worker.
5266     ResourceMark rm;
5267     HandleMark   hm;
5268 
5269     G1STWIsAliveClosure is_alive(_g1h);
5270 
5271     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
5272     pss->set_ref_processor(NULL);
5273 
5274     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, pss);
5275 
5276     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5277 
5278     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5279 
5280     if (_g1h->collector_state()->during_initial_mark_pause()) {
5281       // We also need to mark copied objects.
5282       copy_non_heap_cl = &copy_mark_non_heap_cl;
5283     }
5284 
5285     // Keep alive closure.
5286     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5287 
5288     // Complete GC closure
5289     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5290 
5291     // Call the reference processing task's work routine.
5292     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5293 
5294     // Note we cannot assert that the refs array is empty here as not all
5295     // of the processing tasks (specifically phase2 - pp2_work) execute
5296     // the complete_gc closure (which ordinarily would drain the queue) so
5297     // the queue may not be empty.
5298   }
5299 };
5300 
5301 // Driver routine for parallel reference processing.
5302 // Creates an instance of the ref processing gang
5303 // task and has the worker threads execute it.
5304 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5305   assert(_workers != NULL, "Need parallel worker threads.");
5306 
5307   ParallelTaskTerminator terminator(_active_workers, _queues);
5308   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5309 
5310   _workers->run_task(&proc_task_proxy);
5311 }
5312 
5313 // Gang task for parallel reference enqueueing.
5314 
5315 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5316   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5317   EnqueueTask& _enq_task;
5318 
5319 public:
5320   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5321     AbstractGangTask("Enqueue reference objects in parallel"),
5322     _enq_task(enq_task)
5323   { }
5324 
5325   virtual void work(uint worker_id) {
5326     _enq_task.work(worker_id);
5327   }
5328 };
5329 
5330 // Driver routine for parallel reference enqueueing.
5331 // Creates an instance of the ref enqueueing gang
5332 // task and has the worker threads execute it.
5333 
5334 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5335   assert(_workers != NULL, "Need parallel worker threads.");
5336 
5337   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5338 
5339   _workers->run_task(&enq_task_proxy);
5340 }
5341 
5342 // End of weak reference support closures
5343 
5344 // Abstract task used to preserve (i.e. copy) any referent objects
5345 // that are in the collection set and are pointed to by reference
5346 // objects discovered by the CM ref processor.
5347 
5348 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5349 protected:
5350   G1CollectedHeap*         _g1h;
5351   G1ParScanThreadStateSet* _pss;
5352   RefToScanQueueSet*       _queues;
5353   ParallelTaskTerminator   _terminator;
5354   uint                     _n_workers;
5355 
5356 public:
5357   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5358     AbstractGangTask("ParPreserveCMReferents"),
5359     _g1h(g1h),
5360     _pss(per_thread_states),
5361     _queues(task_queues),
5362     _terminator(workers, _queues),
5363     _n_workers(workers)
5364   { }
5365 
5366   void work(uint worker_id) {
5367     ResourceMark rm;
5368     HandleMark   hm;
5369 
5370     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
5371     pss->set_ref_processor(NULL);
5372     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5373 
5374     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, pss);
5375 
5376     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5377 
5378     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5379 
5380     if (_g1h->collector_state()->during_initial_mark_pause()) {
5381       // We also need to mark copied objects.
5382       copy_non_heap_cl = &copy_mark_non_heap_cl;
5383     }
5384 
5385     // Is alive closure
5386     G1AlwaysAliveClosure always_alive(_g1h);
5387 
5388     // Copying keep alive closure. Applied to referent objects that need
5389     // to be copied.
5390     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5391 
5392     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5393 
5394     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5395     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5396 
5397     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5398     // So this must be true - but assert just in case someone decides to
5399     // change the worker ids.
5400     assert(worker_id < limit, "sanity");
5401     assert(!rp->discovery_is_atomic(), "check this code");
5402 
5403     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5404     for (uint idx = worker_id; idx < limit; idx += stride) {
5405       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5406 
5407       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5408       while (iter.has_next()) {
5409         // Since discovery is not atomic for the CM ref processor, we
5410         // can see some null referent objects.
5411         iter.load_ptrs(DEBUG_ONLY(true));
5412         oop ref = iter.obj();
5413 
5414         // This will filter nulls.
5415         if (iter.is_referent_alive()) {
5416           iter.make_referent_alive();
5417         }
5418         iter.move_to_next();
5419       }
5420     }
5421 
5422     // Drain the queue - which may cause stealing
5423     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5424     drain_queue.do_void();
5425     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5426     assert(pss->queue_is_empty(), "should be");
5427   }
5428 };
5429 
5430 // Weak Reference processing during an evacuation pause (part 1).
5431 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5432   double ref_proc_start = os::elapsedTime();
5433 
5434   ReferenceProcessor* rp = _ref_processor_stw;
5435   assert(rp->discovery_enabled(), "should have been enabled");
5436 
5437   // Any reference objects, in the collection set, that were 'discovered'
5438   // by the CM ref processor should have already been copied (either by
5439   // applying the external root copy closure to the discovered lists, or
5440   // by following an RSet entry).
5441   //
5442   // But some of the referents, that are in the collection set, that these
5443   // reference objects point to may not have been copied: the STW ref
5444   // processor would have seen that the reference object had already
5445   // been 'discovered' and would have skipped discovering the reference,
5446   // but would not have treated the reference object as a regular oop.
5447   // As a result the copy closure would not have been applied to the
5448   // referent object.
5449   //
5450   // We need to explicitly copy these referent objects - the references
5451   // will be processed at the end of remarking.
5452   //
5453   // We also need to do this copying before we process the reference
5454   // objects discovered by the STW ref processor in case one of these
5455   // referents points to another object which is also referenced by an
5456   // object discovered by the STW ref processor.
5457 
5458   uint no_of_gc_workers = workers()->active_workers();
5459 
5460   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5461                                                  per_thread_states,
5462                                                  no_of_gc_workers,
5463                                                  _task_queues);
5464 
5465   workers()->run_task(&keep_cm_referents);
5466 
5467   // Closure to test whether a referent is alive.
5468   G1STWIsAliveClosure is_alive(this);
5469 
5470   // Even when parallel reference processing is enabled, the processing
5471   // of JNI refs is serial and performed serially by the current thread
5472   // rather than by a worker. The following PSS will be used for processing
5473   // JNI refs.
5474 
5475   // Use only a single queue for this PSS.
5476   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
5477   pss->set_ref_processor(NULL);
5478   assert(pss->queue_is_empty(), "pre-condition");
5479 
5480   // We do not embed a reference processor in the copying/scanning
5481   // closures while we're actually processing the discovered
5482   // reference objects.
5483 
5484   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, pss);
5485 
5486   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss);
5487 
5488   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5489 
5490   if (collector_state()->during_initial_mark_pause()) {
5491     // We also need to mark copied objects.
5492     copy_non_heap_cl = &copy_mark_non_heap_cl;
5493   }
5494 
5495   // Keep alive closure.
5496   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss);
5497 
5498   // Serial Complete GC closure
5499   G1STWDrainQueueClosure drain_queue(this, pss);
5500 
5501   // Setup the soft refs policy...
5502   rp->setup_policy(false);
5503 
5504   ReferenceProcessorStats stats;
5505   if (!rp->processing_is_mt()) {
5506     // Serial reference processing...
5507     stats = rp->process_discovered_references(&is_alive,
5508                                               &keep_alive,
5509                                               &drain_queue,
5510                                               NULL,
5511                                               _gc_timer_stw,
5512                                               _gc_tracer_stw->gc_id());
5513   } else {
5514     // Parallel reference processing
5515     assert(rp->num_q() == no_of_gc_workers, "sanity");
5516     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5517 
5518     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5519     stats = rp->process_discovered_references(&is_alive,
5520                                               &keep_alive,
5521                                               &drain_queue,
5522                                               &par_task_executor,
5523                                               _gc_timer_stw,
5524                                               _gc_tracer_stw->gc_id());
5525   }
5526 
5527   _gc_tracer_stw->report_gc_reference_stats(stats);
5528 
5529   // We have completed copying any necessary live referent objects.
5530   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5531 
5532   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5533   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5534 }
5535 
5536 // Weak Reference processing during an evacuation pause (part 2).
5537 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5538   double ref_enq_start = os::elapsedTime();
5539 
5540   ReferenceProcessor* rp = _ref_processor_stw;
5541   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5542 
5543   // Now enqueue any remaining on the discovered lists on to
5544   // the pending list.
5545   if (!rp->processing_is_mt()) {
5546     // Serial reference processing...
5547     rp->enqueue_discovered_references();
5548   } else {
5549     // Parallel reference enqueueing
5550 
5551     uint n_workers = workers()->active_workers();
5552 
5553     assert(rp->num_q() == n_workers, "sanity");
5554     assert(n_workers <= rp->max_num_q(), "sanity");
5555 
5556     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5557     rp->enqueue_discovered_references(&par_task_executor);
5558   }
5559 
5560   rp->verify_no_references_recorded();
5561   assert(!rp->discovery_enabled(), "should have been disabled");
5562 
5563   // FIXME
5564   // CM's reference processing also cleans up the string and symbol tables.
5565   // Should we do that here also? We could, but it is a serial operation
5566   // and could significantly increase the pause time.
5567 
5568   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5569   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5570 }
5571 
5572 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5573   _expand_heap_after_alloc_failure = true;
5574   _evacuation_failed = false;
5575 
5576   // Should G1EvacuationFailureALot be in effect for this GC?
5577   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5578 
5579   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5580 
5581   // Disable the hot card cache.
5582   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5583   hot_card_cache->reset_hot_cache_claimed_index();
5584   hot_card_cache->set_use_cache(false);
5585 
5586   const uint n_workers = workers()->active_workers();
5587 
5588   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5589   double start_par_time_sec = os::elapsedTime();
5590   double end_par_time_sec;
5591 
5592   {
5593     G1RootProcessor root_processor(this, n_workers);
5594     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5595     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5596     if (collector_state()->during_initial_mark_pause()) {
5597       ClassLoaderDataGraph::clear_claimed_marks();
5598     }
5599 
5600     // The individual threads will set their evac-failure closures.
5601     if (PrintTerminationStats) {
5602       print_termination_stats_hdr(gclog_or_tty);
5603     }
5604 
5605     workers()->run_task(&g1_par_task);
5606     end_par_time_sec = os::elapsedTime();
5607 
5608     // Closing the inner scope will execute the destructor
5609     // for the G1RootProcessor object. We record the current
5610     // elapsed time before closing the scope so that time
5611     // taken for the destructor is NOT included in the
5612     // reported parallel time.
5613   }
5614 
5615   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5616 
5617   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5618   phase_times->record_par_time(par_time_ms);
5619 
5620   double code_root_fixup_time_ms =
5621         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5622   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5623 
5624   // Process any discovered reference objects - we have
5625   // to do this _before_ we retire the GC alloc regions
5626   // as we may have to copy some 'reachable' referent
5627   // objects (and their reachable sub-graphs) that were
5628   // not copied during the pause.
5629   process_discovered_references(per_thread_states);
5630 
5631   if (G1StringDedup::is_enabled()) {
5632     double fixup_start = os::elapsedTime();
5633 
5634     G1STWIsAliveClosure is_alive(this);
5635     G1KeepAliveClosure keep_alive(this);
5636     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5637 
5638     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5639     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5640   }
5641 
5642   _allocator->release_gc_alloc_regions(evacuation_info);
5643   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5644 
5645   per_thread_states->flush();
5646 
5647   record_obj_copy_mem_stats();
5648 
5649   // Reset and re-enable the hot card cache.
5650   // Note the counts for the cards in the regions in the
5651   // collection set are reset when the collection set is freed.
5652   hot_card_cache->reset_hot_cache();
5653   hot_card_cache->set_use_cache(true);
5654 
5655   purge_code_root_memory();
5656 
5657   if (evacuation_failed()) {
5658     remove_self_forwarding_pointers();
5659 
5660     // Reset the G1EvacuationFailureALot counters and flags
5661     // Note: the values are reset only when an actual
5662     // evacuation failure occurs.
5663     NOT_PRODUCT(reset_evacuation_should_fail();)
5664   }
5665 
5666   // Enqueue any remaining references remaining on the STW
5667   // reference processor's discovered lists. We need to do
5668   // this after the card table is cleaned (and verified) as
5669   // the act of enqueueing entries on to the pending list
5670   // will log these updates (and dirty their associated
5671   // cards). We need these updates logged to update any
5672   // RSets.
5673   enqueue_discovered_references(per_thread_states);
5674 
5675   redirty_logged_cards();
5676 #if defined(COMPILER2) || INCLUDE_JVMCI
5677   DerivedPointerTable::update_pointers();
5678 #endif
5679 }
5680 
5681 void G1CollectedHeap::record_obj_copy_mem_stats() {
5682   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5683                                                create_g1_evac_summary(&_old_evac_stats));
5684 }
5685 
5686 void G1CollectedHeap::free_region(HeapRegion* hr,
5687                                   FreeRegionList* free_list,
5688                                   bool par,
5689                                   bool locked) {
5690   assert(!hr->is_free(), "the region should not be free");
5691   assert(!hr->is_empty(), "the region should not be empty");
5692   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5693   assert(free_list != NULL, "pre-condition");
5694 
5695   if (G1VerifyBitmaps) {
5696     MemRegion mr(hr->bottom(), hr->end());
5697     concurrent_mark()->clearRangePrevBitmap(mr);
5698   }
5699 
5700   // Clear the card counts for this region.
5701   // Note: we only need to do this if the region is not young
5702   // (since we don't refine cards in young regions).
5703   if (!hr->is_young()) {
5704     _cg1r->hot_card_cache()->reset_card_counts(hr);
5705   }
5706   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5707   free_list->add_ordered(hr);
5708 }
5709 
5710 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5711                                      FreeRegionList* free_list,
5712                                      bool par) {
5713   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5714   assert(free_list != NULL, "pre-condition");
5715 
5716   size_t hr_capacity = hr->capacity();
5717   // We need to read this before we make the region non-humongous,
5718   // otherwise the information will be gone.
5719   uint last_index = hr->last_hc_index();
5720   hr->clear_humongous();
5721   free_region(hr, free_list, par);
5722 
5723   uint i = hr->hrm_index() + 1;
5724   while (i < last_index) {
5725     HeapRegion* curr_hr = region_at(i);
5726     assert(curr_hr->is_continues_humongous(), "invariant");
5727     curr_hr->clear_humongous();
5728     free_region(curr_hr, free_list, par);
5729     i += 1;
5730   }
5731 }
5732 
5733 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5734                                        const HeapRegionSetCount& humongous_regions_removed) {
5735   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5736     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5737     _old_set.bulk_remove(old_regions_removed);
5738     _humongous_set.bulk_remove(humongous_regions_removed);
5739   }
5740 
5741 }
5742 
5743 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5744   assert(list != NULL, "list can't be null");
5745   if (!list->is_empty()) {
5746     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5747     _hrm.insert_list_into_free_list(list);
5748   }
5749 }
5750 
5751 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5752   decrease_used(bytes);
5753 }
5754 
5755 class G1ParCleanupCTTask : public AbstractGangTask {
5756   G1SATBCardTableModRefBS* _ct_bs;
5757   G1CollectedHeap* _g1h;
5758   HeapRegion* volatile _su_head;
5759 public:
5760   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5761                      G1CollectedHeap* g1h) :
5762     AbstractGangTask("G1 Par Cleanup CT Task"),
5763     _ct_bs(ct_bs), _g1h(g1h) { }
5764 
5765   void work(uint worker_id) {
5766     HeapRegion* r;
5767     while (r = _g1h->pop_dirty_cards_region()) {
5768       clear_cards(r);
5769     }
5770   }
5771 
5772   void clear_cards(HeapRegion* r) {
5773     // Cards of the survivors should have already been dirtied.
5774     if (!r->is_survivor()) {
5775       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5776     }
5777   }
5778 };
5779 
5780 #ifndef PRODUCT
5781 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5782   G1CollectedHeap* _g1h;
5783   G1SATBCardTableModRefBS* _ct_bs;
5784 public:
5785   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5786     : _g1h(g1h), _ct_bs(ct_bs) { }
5787   virtual bool doHeapRegion(HeapRegion* r) {
5788     if (r->is_survivor()) {
5789       _g1h->verify_dirty_region(r);
5790     } else {
5791       _g1h->verify_not_dirty_region(r);
5792     }
5793     return false;
5794   }
5795 };
5796 
5797 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5798   // All of the region should be clean.
5799   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5800   MemRegion mr(hr->bottom(), hr->end());
5801   ct_bs->verify_not_dirty_region(mr);
5802 }
5803 
5804 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5805   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5806   // dirty allocated blocks as they allocate them. The thread that
5807   // retires each region and replaces it with a new one will do a
5808   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5809   // not dirty that area (one less thing to have to do while holding
5810   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5811   // is dirty.
5812   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5813   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5814   if (hr->is_young()) {
5815     ct_bs->verify_g1_young_region(mr);
5816   } else {
5817     ct_bs->verify_dirty_region(mr);
5818   }
5819 }
5820 
5821 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5822   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5823   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5824     verify_dirty_region(hr);
5825   }
5826 }
5827 
5828 void G1CollectedHeap::verify_dirty_young_regions() {
5829   verify_dirty_young_list(_young_list->first_region());
5830 }
5831 
5832 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5833                                                HeapWord* tams, HeapWord* end) {
5834   guarantee(tams <= end,
5835             err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5836   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5837   if (result < end) {
5838     gclog_or_tty->cr();
5839     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5840                            bitmap_name, p2i(result));
5841     gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5842                            bitmap_name, p2i(tams), p2i(end));
5843     return false;
5844   }
5845   return true;
5846 }
5847 
5848 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5849   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5850   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5851 
5852   HeapWord* bottom = hr->bottom();
5853   HeapWord* ptams  = hr->prev_top_at_mark_start();
5854   HeapWord* ntams  = hr->next_top_at_mark_start();
5855   HeapWord* end    = hr->end();
5856 
5857   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5858 
5859   bool res_n = true;
5860   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5861   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5862   // if we happen to be in that state.
5863   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5864     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5865   }
5866   if (!res_p || !res_n) {
5867     gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5868                            HR_FORMAT_PARAMS(hr));
5869     gclog_or_tty->print_cr("#### Caller: %s", caller);
5870     return false;
5871   }
5872   return true;
5873 }
5874 
5875 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5876   if (!G1VerifyBitmaps) return;
5877 
5878   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5879 }
5880 
5881 class G1VerifyBitmapClosure : public HeapRegionClosure {
5882 private:
5883   const char* _caller;
5884   G1CollectedHeap* _g1h;
5885   bool _failures;
5886 
5887 public:
5888   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5889     _caller(caller), _g1h(g1h), _failures(false) { }
5890 
5891   bool failures() { return _failures; }
5892 
5893   virtual bool doHeapRegion(HeapRegion* hr) {
5894     if (hr->is_continues_humongous()) return false;
5895 
5896     bool result = _g1h->verify_bitmaps(_caller, hr);
5897     if (!result) {
5898       _failures = true;
5899     }
5900     return false;
5901   }
5902 };
5903 
5904 void G1CollectedHeap::check_bitmaps(const char* caller) {
5905   if (!G1VerifyBitmaps) return;
5906 
5907   G1VerifyBitmapClosure cl(caller, this);
5908   heap_region_iterate(&cl);
5909   guarantee(!cl.failures(), "bitmap verification");
5910 }
5911 
5912 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5913  private:
5914   bool _failures;
5915  public:
5916   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5917 
5918   virtual bool doHeapRegion(HeapRegion* hr) {
5919     uint i = hr->hrm_index();
5920     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5921     if (hr->is_humongous()) {
5922       if (hr->in_collection_set()) {
5923         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5924         _failures = true;
5925         return true;
5926       }
5927       if (cset_state.is_in_cset()) {
5928         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5929         _failures = true;
5930         return true;
5931       }
5932       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5933         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5934         _failures = true;
5935         return true;
5936       }
5937     } else {
5938       if (cset_state.is_humongous()) {
5939         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5940         _failures = true;
5941         return true;
5942       }
5943       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5944         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5945                                hr->in_collection_set(), cset_state.value(), i);
5946         _failures = true;
5947         return true;
5948       }
5949       if (cset_state.is_in_cset()) {
5950         if (hr->is_young() != (cset_state.is_young())) {
5951           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5952                                  hr->is_young(), cset_state.value(), i);
5953           _failures = true;
5954           return true;
5955         }
5956         if (hr->is_old() != (cset_state.is_old())) {
5957           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5958                                  hr->is_old(), cset_state.value(), i);
5959           _failures = true;
5960           return true;
5961         }
5962       }
5963     }
5964     return false;
5965   }
5966 
5967   bool failures() const { return _failures; }
5968 };
5969 
5970 bool G1CollectedHeap::check_cset_fast_test() {
5971   G1CheckCSetFastTableClosure cl;
5972   _hrm.iterate(&cl);
5973   return !cl.failures();
5974 }
5975 #endif // PRODUCT
5976 
5977 void G1CollectedHeap::cleanUpCardTable() {
5978   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5979   double start = os::elapsedTime();
5980 
5981   {
5982     // Iterate over the dirty cards region list.
5983     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5984 
5985     workers()->run_task(&cleanup_task);
5986 #ifndef PRODUCT
5987     if (G1VerifyCTCleanup || VerifyAfterGC) {
5988       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5989       heap_region_iterate(&cleanup_verifier);
5990     }
5991 #endif
5992   }
5993 
5994   double elapsed = os::elapsedTime() - start;
5995   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5996 }
5997 
5998 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5999   size_t pre_used = 0;
6000   FreeRegionList local_free_list("Local List for CSet Freeing");
6001 
6002   double young_time_ms     = 0.0;
6003   double non_young_time_ms = 0.0;
6004 
6005   // Since the collection set is a superset of the the young list,
6006   // all we need to do to clear the young list is clear its
6007   // head and length, and unlink any young regions in the code below
6008   _young_list->clear();
6009 
6010   G1CollectorPolicy* policy = g1_policy();
6011 
6012   double start_sec = os::elapsedTime();
6013   bool non_young = true;
6014 
6015   HeapRegion* cur = cs_head;
6016   int age_bound = -1;
6017   size_t rs_lengths = 0;
6018 
6019   while (cur != NULL) {
6020     assert(!is_on_master_free_list(cur), "sanity");
6021     if (non_young) {
6022       if (cur->is_young()) {
6023         double end_sec = os::elapsedTime();
6024         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6025         non_young_time_ms += elapsed_ms;
6026 
6027         start_sec = os::elapsedTime();
6028         non_young = false;
6029       }
6030     } else {
6031       if (!cur->is_young()) {
6032         double end_sec = os::elapsedTime();
6033         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6034         young_time_ms += elapsed_ms;
6035 
6036         start_sec = os::elapsedTime();
6037         non_young = true;
6038       }
6039     }
6040 
6041     rs_lengths += cur->rem_set()->occupied_locked();
6042 
6043     HeapRegion* next = cur->next_in_collection_set();
6044     assert(cur->in_collection_set(), "bad CS");
6045     cur->set_next_in_collection_set(NULL);
6046     clear_in_cset(cur);
6047 
6048     if (cur->is_young()) {
6049       int index = cur->young_index_in_cset();
6050       assert(index != -1, "invariant");
6051       assert((uint) index < policy->young_cset_region_length(), "invariant");
6052       size_t words_survived = surviving_young_words[index];
6053       cur->record_surv_words_in_group(words_survived);
6054 
6055       // At this point the we have 'popped' cur from the collection set
6056       // (linked via next_in_collection_set()) but it is still in the
6057       // young list (linked via next_young_region()). Clear the
6058       // _next_young_region field.
6059       cur->set_next_young_region(NULL);
6060     } else {
6061       int index = cur->young_index_in_cset();
6062       assert(index == -1, "invariant");
6063     }
6064 
6065     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6066             (!cur->is_young() && cur->young_index_in_cset() == -1),
6067             "invariant" );
6068 
6069     if (!cur->evacuation_failed()) {
6070       MemRegion used_mr = cur->used_region();
6071 
6072       // And the region is empty.
6073       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6074       pre_used += cur->used();
6075       free_region(cur, &local_free_list, false /* par */, true /* locked */);
6076     } else {
6077       cur->uninstall_surv_rate_group();
6078       if (cur->is_young()) {
6079         cur->set_young_index_in_cset(-1);
6080       }
6081       cur->set_evacuation_failed(false);
6082       // The region is now considered to be old.
6083       cur->set_old();
6084       // Do some allocation statistics accounting. Regions that failed evacuation
6085       // are always made old, so there is no need to update anything in the young
6086       // gen statistics, but we need to update old gen statistics.
6087       size_t used_words = cur->marked_bytes() / HeapWordSize;
6088       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
6089       _old_set.add(cur);
6090       evacuation_info.increment_collectionset_used_after(cur->used());
6091     }
6092     cur = next;
6093   }
6094 
6095   evacuation_info.set_regions_freed(local_free_list.length());
6096   policy->record_max_rs_lengths(rs_lengths);
6097   policy->cset_regions_freed();
6098 
6099   double end_sec = os::elapsedTime();
6100   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6101 
6102   if (non_young) {
6103     non_young_time_ms += elapsed_ms;
6104   } else {
6105     young_time_ms += elapsed_ms;
6106   }
6107 
6108   prepend_to_freelist(&local_free_list);
6109   decrement_summary_bytes(pre_used);
6110   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6111   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6112 }
6113 
6114 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6115  private:
6116   FreeRegionList* _free_region_list;
6117   HeapRegionSet* _proxy_set;
6118   HeapRegionSetCount _humongous_regions_removed;
6119   size_t _freed_bytes;
6120  public:
6121 
6122   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6123     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6124   }
6125 
6126   virtual bool doHeapRegion(HeapRegion* r) {
6127     if (!r->is_starts_humongous()) {
6128       return false;
6129     }
6130 
6131     G1CollectedHeap* g1h = G1CollectedHeap::heap();
6132 
6133     oop obj = (oop)r->bottom();
6134     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6135 
6136     // The following checks whether the humongous object is live are sufficient.
6137     // The main additional check (in addition to having a reference from the roots
6138     // or the young gen) is whether the humongous object has a remembered set entry.
6139     //
6140     // A humongous object cannot be live if there is no remembered set for it
6141     // because:
6142     // - there can be no references from within humongous starts regions referencing
6143     // the object because we never allocate other objects into them.
6144     // (I.e. there are no intra-region references that may be missed by the
6145     // remembered set)
6146     // - as soon there is a remembered set entry to the humongous starts region
6147     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6148     // until the end of a concurrent mark.
6149     //
6150     // It is not required to check whether the object has been found dead by marking
6151     // or not, in fact it would prevent reclamation within a concurrent cycle, as
6152     // all objects allocated during that time are considered live.
6153     // SATB marking is even more conservative than the remembered set.
6154     // So if at this point in the collection there is no remembered set entry,
6155     // nobody has a reference to it.
6156     // At the start of collection we flush all refinement logs, and remembered sets
6157     // are completely up-to-date wrt to references to the humongous object.
6158     //
6159     // Other implementation considerations:
6160     // - never consider object arrays at this time because they would pose
6161     // considerable effort for cleaning up the the remembered sets. This is
6162     // required because stale remembered sets might reference locations that
6163     // are currently allocated into.
6164     uint region_idx = r->hrm_index();
6165     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6166         !r->rem_set()->is_empty()) {
6167 
6168       if (G1TraceEagerReclaimHumongousObjects) {
6169         gclog_or_tty->print_cr("Live humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
6170                                region_idx,
6171                                (size_t)obj->size() * HeapWordSize,
6172                                p2i(r->bottom()),
6173                                r->region_num(),
6174                                r->rem_set()->occupied(),
6175                                r->rem_set()->strong_code_roots_list_length(),
6176                                next_bitmap->isMarked(r->bottom()),
6177                                g1h->is_humongous_reclaim_candidate(region_idx),
6178                                obj->is_typeArray()
6179                               );
6180       }
6181 
6182       return false;
6183     }
6184 
6185     guarantee(obj->is_typeArray(),
6186               err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6187                       PTR_FORMAT " is not.",
6188                       p2i(r->bottom())));
6189 
6190     if (G1TraceEagerReclaimHumongousObjects) {
6191       gclog_or_tty->print_cr("Dead humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
6192                              region_idx,
6193                              (size_t)obj->size() * HeapWordSize,
6194                              p2i(r->bottom()),
6195                              r->region_num(),
6196                              r->rem_set()->occupied(),
6197                              r->rem_set()->strong_code_roots_list_length(),
6198                              next_bitmap->isMarked(r->bottom()),
6199                              g1h->is_humongous_reclaim_candidate(region_idx),
6200                              obj->is_typeArray()
6201                             );
6202     }
6203     // Need to clear mark bit of the humongous object if already set.
6204     if (next_bitmap->isMarked(r->bottom())) {
6205       next_bitmap->clear(r->bottom());
6206     }
6207     _freed_bytes += r->used();
6208     r->set_containing_set(NULL);
6209     _humongous_regions_removed.increment(1u, r->capacity());
6210     g1h->free_humongous_region(r, _free_region_list, false);
6211 
6212     return false;
6213   }
6214 
6215   HeapRegionSetCount& humongous_free_count() {
6216     return _humongous_regions_removed;
6217   }
6218 
6219   size_t bytes_freed() const {
6220     return _freed_bytes;
6221   }
6222 
6223   size_t humongous_reclaimed() const {
6224     return _humongous_regions_removed.length();
6225   }
6226 };
6227 
6228 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6229   assert_at_safepoint(true);
6230 
6231   if (!G1EagerReclaimHumongousObjects ||
6232       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6233     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6234     return;
6235   }
6236 
6237   double start_time = os::elapsedTime();
6238 
6239   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6240 
6241   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6242   heap_region_iterate(&cl);
6243 
6244   HeapRegionSetCount empty_set;
6245   remove_from_old_sets(empty_set, cl.humongous_free_count());
6246 
6247   G1HRPrinter* hrp = hr_printer();
6248   if (hrp->is_active()) {
6249     FreeRegionListIterator iter(&local_cleanup_list);
6250     while (iter.more_available()) {
6251       HeapRegion* hr = iter.get_next();
6252       hrp->cleanup(hr);
6253     }
6254   }
6255 
6256   prepend_to_freelist(&local_cleanup_list);
6257   decrement_summary_bytes(cl.bytes_freed());
6258 
6259   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6260                                                                     cl.humongous_reclaimed());
6261 }
6262 
6263 // This routine is similar to the above but does not record
6264 // any policy statistics or update free lists; we are abandoning
6265 // the current incremental collection set in preparation of a
6266 // full collection. After the full GC we will start to build up
6267 // the incremental collection set again.
6268 // This is only called when we're doing a full collection
6269 // and is immediately followed by the tearing down of the young list.
6270 
6271 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6272   HeapRegion* cur = cs_head;
6273 
6274   while (cur != NULL) {
6275     HeapRegion* next = cur->next_in_collection_set();
6276     assert(cur->in_collection_set(), "bad CS");
6277     cur->set_next_in_collection_set(NULL);
6278     clear_in_cset(cur);
6279     cur->set_young_index_in_cset(-1);
6280     cur = next;
6281   }
6282 }
6283 
6284 void G1CollectedHeap::set_free_regions_coming() {
6285   if (G1ConcRegionFreeingVerbose) {
6286     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6287                            "setting free regions coming");
6288   }
6289 
6290   assert(!free_regions_coming(), "pre-condition");
6291   _free_regions_coming = true;
6292 }
6293 
6294 void G1CollectedHeap::reset_free_regions_coming() {
6295   assert(free_regions_coming(), "pre-condition");
6296 
6297   {
6298     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6299     _free_regions_coming = false;
6300     SecondaryFreeList_lock->notify_all();
6301   }
6302 
6303   if (G1ConcRegionFreeingVerbose) {
6304     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6305                            "reset free regions coming");
6306   }
6307 }
6308 
6309 void G1CollectedHeap::wait_while_free_regions_coming() {
6310   // Most of the time we won't have to wait, so let's do a quick test
6311   // first before we take the lock.
6312   if (!free_regions_coming()) {
6313     return;
6314   }
6315 
6316   if (G1ConcRegionFreeingVerbose) {
6317     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6318                            "waiting for free regions");
6319   }
6320 
6321   {
6322     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6323     while (free_regions_coming()) {
6324       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6325     }
6326   }
6327 
6328   if (G1ConcRegionFreeingVerbose) {
6329     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6330                            "done waiting for free regions");
6331   }
6332 }
6333 
6334 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6335   return _allocator->is_retained_old_region(hr);
6336 }
6337 
6338 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6339   _young_list->push_region(hr);
6340 }
6341 
6342 class NoYoungRegionsClosure: public HeapRegionClosure {
6343 private:
6344   bool _success;
6345 public:
6346   NoYoungRegionsClosure() : _success(true) { }
6347   bool doHeapRegion(HeapRegion* r) {
6348     if (r->is_young()) {
6349       gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6350                              p2i(r->bottom()), p2i(r->end()));
6351       _success = false;
6352     }
6353     return false;
6354   }
6355   bool success() { return _success; }
6356 };
6357 
6358 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6359   bool ret = _young_list->check_list_empty(check_sample);
6360 
6361   if (check_heap) {
6362     NoYoungRegionsClosure closure;
6363     heap_region_iterate(&closure);
6364     ret = ret && closure.success();
6365   }
6366 
6367   return ret;
6368 }
6369 
6370 class TearDownRegionSetsClosure : public HeapRegionClosure {
6371 private:
6372   HeapRegionSet *_old_set;
6373 
6374 public:
6375   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6376 
6377   bool doHeapRegion(HeapRegion* r) {
6378     if (r->is_old()) {
6379       _old_set->remove(r);
6380     } else {
6381       // We ignore free regions, we'll empty the free list afterwards.
6382       // We ignore young regions, we'll empty the young list afterwards.
6383       // We ignore humongous regions, we're not tearing down the
6384       // humongous regions set.
6385       assert(r->is_free() || r->is_young() || r->is_humongous(),
6386              "it cannot be another type");
6387     }
6388     return false;
6389   }
6390 
6391   ~TearDownRegionSetsClosure() {
6392     assert(_old_set->is_empty(), "post-condition");
6393   }
6394 };
6395 
6396 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6397   assert_at_safepoint(true /* should_be_vm_thread */);
6398 
6399   if (!free_list_only) {
6400     TearDownRegionSetsClosure cl(&_old_set);
6401     heap_region_iterate(&cl);
6402 
6403     // Note that emptying the _young_list is postponed and instead done as
6404     // the first step when rebuilding the regions sets again. The reason for
6405     // this is that during a full GC string deduplication needs to know if
6406     // a collected region was young or old when the full GC was initiated.
6407   }
6408   _hrm.remove_all_free_regions();
6409 }
6410 
6411 void G1CollectedHeap::increase_used(size_t bytes) {
6412   _summary_bytes_used += bytes;
6413 }
6414 
6415 void G1CollectedHeap::decrease_used(size_t bytes) {
6416   assert(_summary_bytes_used >= bytes,
6417          err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6418                  _summary_bytes_used, bytes));
6419   _summary_bytes_used -= bytes;
6420 }
6421 
6422 void G1CollectedHeap::set_used(size_t bytes) {
6423   _summary_bytes_used = bytes;
6424 }
6425 
6426 class RebuildRegionSetsClosure : public HeapRegionClosure {
6427 private:
6428   bool            _free_list_only;
6429   HeapRegionSet*   _old_set;
6430   HeapRegionManager*   _hrm;
6431   size_t          _total_used;
6432 
6433 public:
6434   RebuildRegionSetsClosure(bool free_list_only,
6435                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6436     _free_list_only(free_list_only),
6437     _old_set(old_set), _hrm(hrm), _total_used(0) {
6438     assert(_hrm->num_free_regions() == 0, "pre-condition");
6439     if (!free_list_only) {
6440       assert(_old_set->is_empty(), "pre-condition");
6441     }
6442   }
6443 
6444   bool doHeapRegion(HeapRegion* r) {
6445     if (r->is_continues_humongous()) {
6446       return false;
6447     }
6448 
6449     if (r->is_empty()) {
6450       // Add free regions to the free list
6451       r->set_free();
6452       r->set_allocation_context(AllocationContext::system());
6453       _hrm->insert_into_free_list(r);
6454     } else if (!_free_list_only) {
6455       assert(!r->is_young(), "we should not come across young regions");
6456 
6457       if (r->is_humongous()) {
6458         // We ignore humongous regions. We left the humongous set unchanged.
6459       } else {
6460         // Objects that were compacted would have ended up on regions
6461         // that were previously old or free.  Archive regions (which are
6462         // old) will not have been touched.
6463         assert(r->is_free() || r->is_old(), "invariant");
6464         // We now consider them old, so register as such. Leave
6465         // archive regions set that way, however, while still adding
6466         // them to the old set.
6467         if (!r->is_archive()) {
6468           r->set_old();
6469         }
6470         _old_set->add(r);
6471       }
6472       _total_used += r->used();
6473     }
6474 
6475     return false;
6476   }
6477 
6478   size_t total_used() {
6479     return _total_used;
6480   }
6481 };
6482 
6483 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6484   assert_at_safepoint(true /* should_be_vm_thread */);
6485 
6486   if (!free_list_only) {
6487     _young_list->empty_list();
6488   }
6489 
6490   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6491   heap_region_iterate(&cl);
6492 
6493   if (!free_list_only) {
6494     set_used(cl.total_used());
6495     if (_archive_allocator != NULL) {
6496       _archive_allocator->clear_used();
6497     }
6498   }
6499   assert(used_unlocked() == recalculate_used(),
6500          err_msg("inconsistent used_unlocked(), "
6501                  "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6502                  used_unlocked(), recalculate_used()));
6503 }
6504 
6505 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6506   _refine_cte_cl->set_concurrent(concurrent);
6507 }
6508 
6509 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6510   HeapRegion* hr = heap_region_containing(p);
6511   return hr->is_in(p);
6512 }
6513 
6514 // Methods for the mutator alloc region
6515 
6516 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6517                                                       bool force) {
6518   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6519   assert(!force || g1_policy()->can_expand_young_list(),
6520          "if force is true we should be able to expand the young list");
6521   bool young_list_full = g1_policy()->is_young_list_full();
6522   if (force || !young_list_full) {
6523     HeapRegion* new_alloc_region = new_region(word_size,
6524                                               false /* is_old */,
6525                                               false /* do_expand */);
6526     if (new_alloc_region != NULL) {
6527       set_region_short_lived_locked(new_alloc_region);
6528       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6529       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6530       return new_alloc_region;
6531     }
6532   }
6533   return NULL;
6534 }
6535 
6536 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6537                                                   size_t allocated_bytes) {
6538   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6539   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6540 
6541   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6542   increase_used(allocated_bytes);
6543   _hr_printer.retire(alloc_region);
6544   // We update the eden sizes here, when the region is retired,
6545   // instead of when it's allocated, since this is the point that its
6546   // used space has been recored in _summary_bytes_used.
6547   g1mm()->update_eden_size();
6548 }
6549 
6550 // Methods for the GC alloc regions
6551 
6552 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6553                                                  uint count,
6554                                                  InCSetState dest) {
6555   assert(FreeList_lock->owned_by_self(), "pre-condition");
6556 
6557   if (count < g1_policy()->max_regions(dest)) {
6558     const bool is_survivor = (dest.is_young());
6559     HeapRegion* new_alloc_region = new_region(word_size,
6560                                               !is_survivor,
6561                                               true /* do_expand */);
6562     if (new_alloc_region != NULL) {
6563       // We really only need to do this for old regions given that we
6564       // should never scan survivors. But it doesn't hurt to do it
6565       // for survivors too.
6566       new_alloc_region->record_timestamp();
6567       if (is_survivor) {
6568         new_alloc_region->set_survivor();
6569         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6570         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6571       } else {
6572         new_alloc_region->set_old();
6573         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6574         check_bitmaps("Old Region Allocation", new_alloc_region);
6575       }
6576       bool during_im = collector_state()->during_initial_mark_pause();
6577       new_alloc_region->note_start_of_copying(during_im);
6578       return new_alloc_region;
6579     }
6580   }
6581   return NULL;
6582 }
6583 
6584 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6585                                              size_t allocated_bytes,
6586                                              InCSetState dest) {
6587   bool during_im = collector_state()->during_initial_mark_pause();
6588   alloc_region->note_end_of_copying(during_im);
6589   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6590   if (dest.is_young()) {
6591     young_list()->add_survivor_region(alloc_region);
6592   } else {
6593     _old_set.add(alloc_region);
6594   }
6595   _hr_printer.retire(alloc_region);
6596 }
6597 
6598 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6599   bool expanded = false;
6600   uint index = _hrm.find_highest_free(&expanded);
6601 
6602   if (index != G1_NO_HRM_INDEX) {
6603     if (expanded) {
6604       ergo_verbose1(ErgoHeapSizing,
6605                     "attempt heap expansion",
6606                     ergo_format_reason("requested address range outside heap bounds")
6607                     ergo_format_byte("region size"),
6608                     HeapRegion::GrainWords * HeapWordSize);
6609     }
6610     _hrm.allocate_free_regions_starting_at(index, 1);
6611     return region_at(index);
6612   }
6613   return NULL;
6614 }
6615 
6616 // Heap region set verification
6617 
6618 class VerifyRegionListsClosure : public HeapRegionClosure {
6619 private:
6620   HeapRegionSet*   _old_set;
6621   HeapRegionSet*   _humongous_set;
6622   HeapRegionManager*   _hrm;
6623 
6624 public:
6625   HeapRegionSetCount _old_count;
6626   HeapRegionSetCount _humongous_count;
6627   HeapRegionSetCount _free_count;
6628 
6629   VerifyRegionListsClosure(HeapRegionSet* old_set,
6630                            HeapRegionSet* humongous_set,
6631                            HeapRegionManager* hrm) :
6632     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6633     _old_count(), _humongous_count(), _free_count(){ }
6634 
6635   bool doHeapRegion(HeapRegion* hr) {
6636     if (hr->is_continues_humongous()) {
6637       return false;
6638     }
6639 
6640     if (hr->is_young()) {
6641       // TODO
6642     } else if (hr->is_starts_humongous()) {
6643       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6644       _humongous_count.increment(1u, hr->capacity());
6645     } else if (hr->is_empty()) {
6646       assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6647       _free_count.increment(1u, hr->capacity());
6648     } else if (hr->is_old()) {
6649       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6650       _old_count.increment(1u, hr->capacity());
6651     } else {
6652       // There are no other valid region types. Check for one invalid
6653       // one we can identify: pinned without old or humongous set.
6654       assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6655       ShouldNotReachHere();
6656     }
6657     return false;
6658   }
6659 
6660   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6661     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6662     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6663         old_set->total_capacity_bytes(), _old_count.capacity()));
6664 
6665     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6666     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6667         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6668 
6669     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()));
6670     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6671         free_list->total_capacity_bytes(), _free_count.capacity()));
6672   }
6673 };
6674 
6675 void G1CollectedHeap::verify_region_sets() {
6676   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6677 
6678   // First, check the explicit lists.
6679   _hrm.verify();
6680   {
6681     // Given that a concurrent operation might be adding regions to
6682     // the secondary free list we have to take the lock before
6683     // verifying it.
6684     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6685     _secondary_free_list.verify_list();
6686   }
6687 
6688   // If a concurrent region freeing operation is in progress it will
6689   // be difficult to correctly attributed any free regions we come
6690   // across to the correct free list given that they might belong to
6691   // one of several (free_list, secondary_free_list, any local lists,
6692   // etc.). So, if that's the case we will skip the rest of the
6693   // verification operation. Alternatively, waiting for the concurrent
6694   // operation to complete will have a non-trivial effect on the GC's
6695   // operation (no concurrent operation will last longer than the
6696   // interval between two calls to verification) and it might hide
6697   // any issues that we would like to catch during testing.
6698   if (free_regions_coming()) {
6699     return;
6700   }
6701 
6702   // Make sure we append the secondary_free_list on the free_list so
6703   // that all free regions we will come across can be safely
6704   // attributed to the free_list.
6705   append_secondary_free_list_if_not_empty_with_lock();
6706 
6707   // Finally, make sure that the region accounting in the lists is
6708   // consistent with what we see in the heap.
6709 
6710   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6711   heap_region_iterate(&cl);
6712   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6713 }
6714 
6715 // Optimized nmethod scanning
6716 
6717 class RegisterNMethodOopClosure: public OopClosure {
6718   G1CollectedHeap* _g1h;
6719   nmethod* _nm;
6720 
6721   template <class T> void do_oop_work(T* p) {
6722     T heap_oop = oopDesc::load_heap_oop(p);
6723     if (!oopDesc::is_null(heap_oop)) {
6724       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6725       HeapRegion* hr = _g1h->heap_region_containing(obj);
6726       assert(!hr->is_continues_humongous(),
6727              err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6728                      " starting at " HR_FORMAT,
6729                      p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6730 
6731       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6732       hr->add_strong_code_root_locked(_nm);
6733     }
6734   }
6735 
6736 public:
6737   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6738     _g1h(g1h), _nm(nm) {}
6739 
6740   void do_oop(oop* p)       { do_oop_work(p); }
6741   void do_oop(narrowOop* p) { do_oop_work(p); }
6742 };
6743 
6744 class UnregisterNMethodOopClosure: public OopClosure {
6745   G1CollectedHeap* _g1h;
6746   nmethod* _nm;
6747 
6748   template <class T> void do_oop_work(T* p) {
6749     T heap_oop = oopDesc::load_heap_oop(p);
6750     if (!oopDesc::is_null(heap_oop)) {
6751       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6752       HeapRegion* hr = _g1h->heap_region_containing(obj);
6753       assert(!hr->is_continues_humongous(),
6754              err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6755                      " starting at " HR_FORMAT,
6756                      p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6757 
6758       hr->remove_strong_code_root(_nm);
6759     }
6760   }
6761 
6762 public:
6763   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6764     _g1h(g1h), _nm(nm) {}
6765 
6766   void do_oop(oop* p)       { do_oop_work(p); }
6767   void do_oop(narrowOop* p) { do_oop_work(p); }
6768 };
6769 
6770 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6771   CollectedHeap::register_nmethod(nm);
6772 
6773   guarantee(nm != NULL, "sanity");
6774   RegisterNMethodOopClosure reg_cl(this, nm);
6775   nm->oops_do(&reg_cl);
6776 }
6777 
6778 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6779   CollectedHeap::unregister_nmethod(nm);
6780 
6781   guarantee(nm != NULL, "sanity");
6782   UnregisterNMethodOopClosure reg_cl(this, nm);
6783   nm->oops_do(&reg_cl, true);
6784 }
6785 
6786 void G1CollectedHeap::purge_code_root_memory() {
6787   double purge_start = os::elapsedTime();
6788   G1CodeRootSet::purge();
6789   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6790   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6791 }
6792 
6793 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6794   G1CollectedHeap* _g1h;
6795 
6796 public:
6797   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6798     _g1h(g1h) {}
6799 
6800   void do_code_blob(CodeBlob* cb) {
6801     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6802     if (nm == NULL) {
6803       return;
6804     }
6805 
6806     if (ScavengeRootsInCode) {
6807       _g1h->register_nmethod(nm);
6808     }
6809   }
6810 };
6811 
6812 void G1CollectedHeap::rebuild_strong_code_roots() {
6813   RebuildStrongCodeRootClosure blob_cl(this);
6814   CodeCache::blobs_do(&blob_cl);
6815 }
--- EOF ---