1 /*
   2  * Copyright (c) 2001, 2016, 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 "classfile/symbolTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/bufferingOopClosure.hpp"
  32 #include "gc/g1/concurrentG1Refine.hpp"
  33 #include "gc/g1/concurrentG1RefineThread.hpp"
  34 #include "gc/g1/concurrentMarkThread.inline.hpp"
  35 #include "gc/g1/g1Allocator.inline.hpp"
  36 #include "gc/g1/g1CollectedHeap.inline.hpp"
  37 #include "gc/g1/g1CollectorPolicy.hpp"
  38 #include "gc/g1/g1CollectorState.hpp"
  39 #include "gc/g1/g1EvacStats.inline.hpp"
  40 #include "gc/g1/g1GCPhaseTimes.hpp"
  41 #include "gc/g1/g1HeapTransition.hpp"
  42 #include "gc/g1/g1HeapVerifier.hpp"
  43 #include "gc/g1/g1MarkSweep.hpp"
  44 #include "gc/g1/g1OopClosures.inline.hpp"
  45 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  46 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  47 #include "gc/g1/g1RemSet.inline.hpp"
  48 #include "gc/g1/g1RootClosures.hpp"
  49 #include "gc/g1/g1RootProcessor.hpp"
  50 #include "gc/g1/g1StringDedup.hpp"
  51 #include "gc/g1/g1YCTypes.hpp"
  52 #include "gc/g1/heapRegion.inline.hpp"
  53 #include "gc/g1/heapRegionRemSet.hpp"
  54 #include "gc/g1/heapRegionSet.inline.hpp"
  55 #include "gc/g1/suspendibleThreadSet.hpp"
  56 #include "gc/g1/vm_operations_g1.hpp"
  57 #include "gc/shared/gcHeapSummary.hpp"
  58 #include "gc/shared/gcId.hpp"
  59 #include "gc/shared/gcLocker.inline.hpp"
  60 #include "gc/shared/gcTimer.hpp"
  61 #include "gc/shared/gcTrace.hpp"
  62 #include "gc/shared/gcTraceTime.inline.hpp"
  63 #include "gc/shared/generationSpec.hpp"
  64 #include "gc/shared/isGCActiveMark.hpp"
  65 #include "gc/shared/referenceProcessor.inline.hpp"
  66 #include "gc/shared/taskqueue.inline.hpp"
  67 #include "logging/log.hpp"
  68 #include "memory/allocation.hpp"
  69 #include "memory/iterator.hpp"
  70 #include "oops/oop.inline.hpp"
  71 #include "runtime/atomic.inline.hpp"
  72 #include "runtime/init.hpp"
  73 #include "runtime/orderAccess.inline.hpp"
  74 #include "runtime/vmThread.hpp"
  75 #include "utilities/globalDefinitions.hpp"
  76 #include "utilities/stack.inline.hpp"
  77 
  78 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  79 
  80 // INVARIANTS/NOTES
  81 //
  82 // All allocation activity covered by the G1CollectedHeap interface is
  83 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  84 // and allocate_new_tlab, which are the "entry" points to the
  85 // allocation code from the rest of the JVM.  (Note that this does not
  86 // apply to TLAB allocation, which is not part of this interface: it
  87 // is done by clients of this interface.)
  88 
  89 // Local to this file.
  90 
  91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  92   bool _concurrent;
  93 public:
  94   RefineCardTableEntryClosure() : _concurrent(true) { }
  95 
  96   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  97     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
  98     // This path is executed by the concurrent refine or mutator threads,
  99     // concurrently, and so we do not care if card_ptr contains references
 100     // that point into the collection set.
 101     assert(!oops_into_cset, "should be");
 102 
 103     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 104       // Caller will actually yield.
 105       return false;
 106     }
 107     // Otherwise, we finished successfully; return true.
 108     return true;
 109   }
 110 
 111   void set_concurrent(bool b) { _concurrent = b; }
 112 };
 113 
 114 
 115 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 116  private:
 117   size_t _num_dirtied;
 118   G1CollectedHeap* _g1h;
 119   G1SATBCardTableLoggingModRefBS* _g1_bs;
 120 
 121   HeapRegion* region_for_card(jbyte* card_ptr) const {
 122     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 123   }
 124 
 125   bool will_become_free(HeapRegion* hr) const {
 126     // A region will be freed by free_collection_set if the region is in the
 127     // collection set and has not had an evacuation failure.
 128     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 129   }
 130 
 131  public:
 132   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 133     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 134 
 135   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 136     HeapRegion* hr = region_for_card(card_ptr);
 137 
 138     // Should only dirty cards in regions that won't be freed.
 139     if (!will_become_free(hr)) {
 140       *card_ptr = CardTableModRefBS::dirty_card_val();
 141       _num_dirtied++;
 142     }
 143 
 144     return true;
 145   }
 146 
 147   size_t num_dirtied()   const { return _num_dirtied; }
 148 };
 149 
 150 
 151 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 152   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 153 }
 154 
 155 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 156   // The from card cache is not the memory that is actually committed. So we cannot
 157   // take advantage of the zero_filled parameter.
 158   reset_from_card_cache(start_idx, num_regions);
 159 }
 160 
 161 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 162 {
 163   // Claim the right to put the region on the dirty cards region list
 164   // by installing a self pointer.
 165   HeapRegion* next = hr->get_next_dirty_cards_region();
 166   if (next == NULL) {
 167     HeapRegion* res = (HeapRegion*)
 168       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 169                           NULL);
 170     if (res == NULL) {
 171       HeapRegion* head;
 172       do {
 173         // Put the region to the dirty cards region list.
 174         head = _dirty_cards_region_list;
 175         next = (HeapRegion*)
 176           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 177         if (next == head) {
 178           assert(hr->get_next_dirty_cards_region() == hr,
 179                  "hr->get_next_dirty_cards_region() != hr");
 180           if (next == NULL) {
 181             // The last region in the list points to itself.
 182             hr->set_next_dirty_cards_region(hr);
 183           } else {
 184             hr->set_next_dirty_cards_region(next);
 185           }
 186         }
 187       } while (next != head);
 188     }
 189   }
 190 }
 191 
 192 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 193 {
 194   HeapRegion* head;
 195   HeapRegion* hr;
 196   do {
 197     head = _dirty_cards_region_list;
 198     if (head == NULL) {
 199       return NULL;
 200     }
 201     HeapRegion* new_head = head->get_next_dirty_cards_region();
 202     if (head == new_head) {
 203       // The last region.
 204       new_head = NULL;
 205     }
 206     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 207                                           head);
 208   } while (hr != head);
 209   assert(hr != NULL, "invariant");
 210   hr->set_next_dirty_cards_region(NULL);
 211   return hr;
 212 }
 213 
 214 // Returns true if the reference points to an object that
 215 // can move in an incremental collection.
 216 bool G1CollectedHeap::is_scavengable(const void* p) {
 217   HeapRegion* hr = heap_region_containing(p);
 218   return !hr->is_pinned();
 219 }
 220 
 221 // Private methods.
 222 
 223 HeapRegion*
 224 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 225   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 226   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 227     if (!_secondary_free_list.is_empty()) {
 228       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 229                                       "secondary_free_list has %u entries",
 230                                       _secondary_free_list.length());
 231       // It looks as if there are free regions available on the
 232       // secondary_free_list. Let's move them to the free_list and try
 233       // again to allocate from it.
 234       append_secondary_free_list();
 235 
 236       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 237              "empty we should have moved at least one entry to the free_list");
 238       HeapRegion* res = _hrm.allocate_free_region(is_old);
 239       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 240                                       "allocated " HR_FORMAT " from secondary_free_list",
 241                                       HR_FORMAT_PARAMS(res));
 242       return res;
 243     }
 244 
 245     // Wait here until we get notified either when (a) there are no
 246     // more free regions coming or (b) some regions have been moved on
 247     // the secondary_free_list.
 248     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 249   }
 250 
 251   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 252                                   "could not allocate from secondary_free_list");
 253   return NULL;
 254 }
 255 
 256 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 257   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 258          "the only time we use this to allocate a humongous region is "
 259          "when we are allocating a single humongous region");
 260 
 261   HeapRegion* res;
 262   if (G1StressConcRegionFreeing) {
 263     if (!_secondary_free_list.is_empty()) {
 264       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 265                                       "forced to look at the secondary_free_list");
 266       res = new_region_try_secondary_free_list(is_old);
 267       if (res != NULL) {
 268         return res;
 269       }
 270     }
 271   }
 272 
 273   res = _hrm.allocate_free_region(is_old);
 274 
 275   if (res == NULL) {
 276     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 277                                     "res == NULL, trying the secondary_free_list");
 278     res = new_region_try_secondary_free_list(is_old);
 279   }
 280   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 281     // Currently, only attempts to allocate GC alloc regions set
 282     // do_expand to true. So, we should only reach here during a
 283     // safepoint. If this assumption changes we might have to
 284     // reconsider the use of _expand_heap_after_alloc_failure.
 285     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 286 
 287     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 288                               word_size * HeapWordSize);
 289 
 290     if (expand(word_size * HeapWordSize)) {
 291       // Given that expand() succeeded in expanding the heap, and we
 292       // always expand the heap by an amount aligned to the heap
 293       // region size, the free list should in theory not be empty.
 294       // In either case allocate_free_region() will check for NULL.
 295       res = _hrm.allocate_free_region(is_old);
 296     } else {
 297       _expand_heap_after_alloc_failure = false;
 298     }
 299   }
 300   return res;
 301 }
 302 
 303 HeapWord*
 304 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 305                                                            uint num_regions,
 306                                                            size_t word_size,
 307                                                            AllocationContext_t context) {
 308   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 309   assert(is_humongous(word_size), "word_size should be humongous");
 310   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 311 
 312   // Index of last region in the series.
 313   uint last = first + num_regions - 1;
 314 
 315   // We need to initialize the region(s) we just discovered. This is
 316   // a bit tricky given that it can happen concurrently with
 317   // refinement threads refining cards on these regions and
 318   // potentially wanting to refine the BOT as they are scanning
 319   // those cards (this can happen shortly after a cleanup; see CR
 320   // 6991377). So we have to set up the region(s) carefully and in
 321   // a specific order.
 322 
 323   // The word size sum of all the regions we will allocate.
 324   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 325   assert(word_size <= word_size_sum, "sanity");
 326 
 327   // This will be the "starts humongous" region.
 328   HeapRegion* first_hr = region_at(first);
 329   // The header of the new object will be placed at the bottom of
 330   // the first region.
 331   HeapWord* new_obj = first_hr->bottom();
 332   // This will be the new top of the new object.
 333   HeapWord* obj_top = new_obj + word_size;
 334 
 335   // First, we need to zero the header of the space that we will be
 336   // allocating. When we update top further down, some refinement
 337   // threads might try to scan the region. By zeroing the header we
 338   // ensure that any thread that will try to scan the region will
 339   // come across the zero klass word and bail out.
 340   //
 341   // NOTE: It would not have been correct to have used
 342   // CollectedHeap::fill_with_object() and make the space look like
 343   // an int array. The thread that is doing the allocation will
 344   // later update the object header to a potentially different array
 345   // type and, for a very short period of time, the klass and length
 346   // fields will be inconsistent. This could cause a refinement
 347   // thread to calculate the object size incorrectly.
 348   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 349 
 350   // How many words we use for filler objects.
 351   size_t word_fill_size = word_size_sum - word_size;
 352 
 353   // How many words memory we "waste" which cannot hold a filler object.
 354   size_t words_not_fillable = 0;
 355 
 356   if (word_fill_size >= min_fill_size()) {
 357     fill_with_objects(obj_top, word_fill_size);
 358   } else if (word_fill_size > 0) {
 359     // We have space to fill, but we cannot fit an object there.
 360     words_not_fillable = word_fill_size;
 361     word_fill_size = 0;
 362   }
 363 
 364   // We will set up the first region as "starts humongous". This
 365   // will also update the BOT covering all the regions to reflect
 366   // that there is a single object that starts at the bottom of the
 367   // first region.
 368   first_hr->set_starts_humongous(obj_top, word_fill_size);
 369   first_hr->set_allocation_context(context);
 370   // Then, if there are any, we will set up the "continues
 371   // humongous" regions.
 372   HeapRegion* hr = NULL;
 373   for (uint i = first + 1; i <= last; ++i) {
 374     hr = region_at(i);
 375     hr->set_continues_humongous(first_hr);
 376     hr->set_allocation_context(context);
 377   }
 378 
 379   // Up to this point no concurrent thread would have been able to
 380   // do any scanning on any region in this series. All the top
 381   // fields still point to bottom, so the intersection between
 382   // [bottom,top] and [card_start,card_end] will be empty. Before we
 383   // update the top fields, we'll do a storestore to make sure that
 384   // no thread sees the update to top before the zeroing of the
 385   // object header and the BOT initialization.
 386   OrderAccess::storestore();
 387 
 388   // Now, we will update the top fields of the "continues humongous"
 389   // regions except the last one.
 390   for (uint i = first; i < last; ++i) {
 391     hr = region_at(i);
 392     hr->set_top(hr->end());
 393   }
 394 
 395   hr = region_at(last);
 396   // If we cannot fit a filler object, we must set top to the end
 397   // of the humongous object, otherwise we cannot iterate the heap
 398   // and the BOT will not be complete.
 399   hr->set_top(hr->end() - words_not_fillable);
 400 
 401   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 402          "obj_top should be in last region");
 403 
 404   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 405 
 406   assert(words_not_fillable == 0 ||
 407          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 408          "Miscalculation in humongous allocation");
 409 
 410   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 411 
 412   for (uint i = first; i <= last; ++i) {
 413     hr = region_at(i);
 414     _humongous_set.add(hr);
 415     _hr_printer.alloc(hr);
 416   }
 417 
 418   return new_obj;
 419 }
 420 
 421 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 422   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 423   return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 424 }
 425 
 426 // If could fit into free regions w/o expansion, try.
 427 // Otherwise, if can expand, do so.
 428 // Otherwise, if using ex regions might help, try with ex given back.
 429 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 430   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 431 
 432   _verifier->verify_region_sets_optional();
 433 
 434   uint first = G1_NO_HRM_INDEX;
 435   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 436 
 437   if (obj_regions == 1) {
 438     // Only one region to allocate, try to use a fast path by directly allocating
 439     // from the free lists. Do not try to expand here, we will potentially do that
 440     // later.
 441     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 442     if (hr != NULL) {
 443       first = hr->hrm_index();
 444     }
 445   } else {
 446     // We can't allocate humongous regions spanning more than one region while
 447     // cleanupComplete() is running, since some of the regions we find to be
 448     // empty might not yet be added to the free list. It is not straightforward
 449     // to know in which list they are on so that we can remove them. We only
 450     // need to do this if we need to allocate more than one region to satisfy the
 451     // current humongous allocation request. If we are only allocating one region
 452     // we use the one-region region allocation code (see above), that already
 453     // potentially waits for regions from the secondary free list.
 454     wait_while_free_regions_coming();
 455     append_secondary_free_list_if_not_empty_with_lock();
 456 
 457     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 458     // are lucky enough to find some.
 459     first = _hrm.find_contiguous_only_empty(obj_regions);
 460     if (first != G1_NO_HRM_INDEX) {
 461       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 462     }
 463   }
 464 
 465   if (first == G1_NO_HRM_INDEX) {
 466     // Policy: We could not find enough regions for the humongous object in the
 467     // free list. Look through the heap to find a mix of free and uncommitted regions.
 468     // If so, try expansion.
 469     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 470     if (first != G1_NO_HRM_INDEX) {
 471       // We found something. Make sure these regions are committed, i.e. expand
 472       // the heap. Alternatively we could do a defragmentation GC.
 473       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 474                                     word_size * HeapWordSize);
 475 
 476 
 477       _hrm.expand_at(first, obj_regions);
 478       g1_policy()->record_new_heap_size(num_regions());
 479 
 480 #ifdef ASSERT
 481       for (uint i = first; i < first + obj_regions; ++i) {
 482         HeapRegion* hr = region_at(i);
 483         assert(hr->is_free(), "sanity");
 484         assert(hr->is_empty(), "sanity");
 485         assert(is_on_master_free_list(hr), "sanity");
 486       }
 487 #endif
 488       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 489     } else {
 490       // Policy: Potentially trigger a defragmentation GC.
 491     }
 492   }
 493 
 494   HeapWord* result = NULL;
 495   if (first != G1_NO_HRM_INDEX) {
 496     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 497                                                        word_size, context);
 498     assert(result != NULL, "it should always return a valid result");
 499 
 500     // A successful humongous object allocation changes the used space
 501     // information of the old generation so we need to recalculate the
 502     // sizes and update the jstat counters here.
 503     g1mm()->update_sizes();
 504   }
 505 
 506   _verifier->verify_region_sets_optional();
 507 
 508   return result;
 509 }
 510 
 511 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 512   assert_heap_not_locked_and_not_at_safepoint();
 513   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 514 
 515   uint dummy_gc_count_before;
 516   uint dummy_gclocker_retry_count = 0;
 517   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 518 }
 519 
 520 HeapWord*
 521 G1CollectedHeap::mem_allocate(size_t word_size,
 522                               bool*  gc_overhead_limit_was_exceeded) {
 523   assert_heap_not_locked_and_not_at_safepoint();
 524 
 525   // Loop until the allocation is satisfied, or unsatisfied after GC.
 526   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 527     uint gc_count_before;
 528 
 529     HeapWord* result = NULL;
 530     if (!is_humongous(word_size)) {
 531       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 532     } else {
 533       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 534     }
 535     if (result != NULL) {
 536       return result;
 537     }
 538 
 539     // Create the garbage collection operation...
 540     VM_G1CollectForAllocation op(gc_count_before, word_size);
 541     op.set_allocation_context(AllocationContext::current());
 542 
 543     // ...and get the VM thread to execute it.
 544     VMThread::execute(&op);
 545 
 546     if (op.prologue_succeeded() && op.pause_succeeded()) {
 547       // If the operation was successful we'll return the result even
 548       // if it is NULL. If the allocation attempt failed immediately
 549       // after a Full GC, it's unlikely we'll be able to allocate now.
 550       HeapWord* result = op.result();
 551       if (result != NULL && !is_humongous(word_size)) {
 552         // Allocations that take place on VM operations do not do any
 553         // card dirtying and we have to do it here. We only have to do
 554         // this for non-humongous allocations, though.
 555         dirty_young_block(result, word_size);
 556       }
 557       return result;
 558     } else {
 559       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 560         return NULL;
 561       }
 562       assert(op.result() == NULL,
 563              "the result should be NULL if the VM op did not succeed");
 564     }
 565 
 566     // Give a warning if we seem to be looping forever.
 567     if ((QueuedAllocationWarningCount > 0) &&
 568         (try_count % QueuedAllocationWarningCount == 0)) {
 569       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 570     }
 571   }
 572 
 573   ShouldNotReachHere();
 574   return NULL;
 575 }
 576 
 577 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 578                                                    AllocationContext_t context,
 579                                                    uint* gc_count_before_ret,
 580                                                    uint* gclocker_retry_count_ret) {
 581   // Make sure you read the note in attempt_allocation_humongous().
 582 
 583   assert_heap_not_locked_and_not_at_safepoint();
 584   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 585          "be called for humongous allocation requests");
 586 
 587   // We should only get here after the first-level allocation attempt
 588   // (attempt_allocation()) failed to allocate.
 589 
 590   // We will loop until a) we manage to successfully perform the
 591   // allocation or b) we successfully schedule a collection which
 592   // fails to perform the allocation. b) is the only case when we'll
 593   // return NULL.
 594   HeapWord* result = NULL;
 595   for (int try_count = 1; /* we'll return */; try_count += 1) {
 596     bool should_try_gc;
 597     uint gc_count_before;
 598 
 599     {
 600       MutexLockerEx x(Heap_lock);
 601       result = _allocator->attempt_allocation_locked(word_size, context);
 602       if (result != NULL) {
 603         return result;
 604       }
 605 
 606       if (GCLocker::is_active_and_needs_gc()) {
 607         if (g1_policy()->can_expand_young_list()) {
 608           // No need for an ergo verbose message here,
 609           // can_expand_young_list() does this when it returns true.
 610           result = _allocator->attempt_allocation_force(word_size, context);
 611           if (result != NULL) {
 612             return result;
 613           }
 614         }
 615         should_try_gc = false;
 616       } else {
 617         // The GCLocker may not be active but the GCLocker initiated
 618         // GC may not yet have been performed (GCLocker::needs_gc()
 619         // returns true). In this case we do not try this GC and
 620         // wait until the GCLocker initiated GC is performed, and
 621         // then retry the allocation.
 622         if (GCLocker::needs_gc()) {
 623           should_try_gc = false;
 624         } else {
 625           // Read the GC count while still holding the Heap_lock.
 626           gc_count_before = total_collections();
 627           should_try_gc = true;
 628         }
 629       }
 630     }
 631 
 632     if (should_try_gc) {
 633       bool succeeded;
 634       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 635                                    GCCause::_g1_inc_collection_pause);
 636       if (result != NULL) {
 637         assert(succeeded, "only way to get back a non-NULL result");
 638         return result;
 639       }
 640 
 641       if (succeeded) {
 642         // If we get here we successfully scheduled a collection which
 643         // failed to allocate. No point in trying to allocate
 644         // further. We'll just return NULL.
 645         MutexLockerEx x(Heap_lock);
 646         *gc_count_before_ret = total_collections();
 647         return NULL;
 648       }
 649     } else {
 650       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 651         MutexLockerEx x(Heap_lock);
 652         *gc_count_before_ret = total_collections();
 653         return NULL;
 654       }
 655       // The GCLocker is either active or the GCLocker initiated
 656       // GC has not yet been performed. Stall until it is and
 657       // then retry the allocation.
 658       GCLocker::stall_until_clear();
 659       (*gclocker_retry_count_ret) += 1;
 660     }
 661 
 662     // We can reach here if we were unsuccessful in scheduling a
 663     // collection (because another thread beat us to it) or if we were
 664     // stalled due to the GC locker. In either can we should retry the
 665     // allocation attempt in case another thread successfully
 666     // performed a collection and reclaimed enough space. We do the
 667     // first attempt (without holding the Heap_lock) here and the
 668     // follow-on attempt will be at the start of the next loop
 669     // iteration (after taking the Heap_lock).
 670     result = _allocator->attempt_allocation(word_size, context);
 671     if (result != NULL) {
 672       return result;
 673     }
 674 
 675     // Give a warning if we seem to be looping forever.
 676     if ((QueuedAllocationWarningCount > 0) &&
 677         (try_count % QueuedAllocationWarningCount == 0)) {
 678       warning("G1CollectedHeap::attempt_allocation_slow() "
 679               "retries %d times", try_count);
 680     }
 681   }
 682 
 683   ShouldNotReachHere();
 684   return NULL;
 685 }
 686 
 687 void G1CollectedHeap::begin_archive_alloc_range() {
 688   assert_at_safepoint(true /* should_be_vm_thread */);
 689   if (_archive_allocator == NULL) {
 690     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 691   }
 692 }
 693 
 694 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 695   // Allocations in archive regions cannot be of a size that would be considered
 696   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 697   // may be different at archive-restore time.
 698   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 699 }
 700 
 701 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 702   assert_at_safepoint(true /* should_be_vm_thread */);
 703   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 704   if (is_archive_alloc_too_large(word_size)) {
 705     return NULL;
 706   }
 707   return _archive_allocator->archive_mem_allocate(word_size);
 708 }
 709 
 710 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 711                                               size_t end_alignment_in_bytes) {
 712   assert_at_safepoint(true /* should_be_vm_thread */);
 713   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 714 
 715   // Call complete_archive to do the real work, filling in the MemRegion
 716   // array with the archive regions.
 717   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 718   delete _archive_allocator;
 719   _archive_allocator = NULL;
 720 }
 721 
 722 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 723   assert(ranges != NULL, "MemRegion array NULL");
 724   assert(count != 0, "No MemRegions provided");
 725   MemRegion reserved = _hrm.reserved();
 726   for (size_t i = 0; i < count; i++) {
 727     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 728       return false;
 729     }
 730   }
 731   return true;
 732 }
 733 
 734 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 735   assert(!is_init_completed(), "Expect to be called at JVM init time");
 736   assert(ranges != NULL, "MemRegion array NULL");
 737   assert(count != 0, "No MemRegions provided");
 738   MutexLockerEx x(Heap_lock);
 739 
 740   MemRegion reserved = _hrm.reserved();
 741   HeapWord* prev_last_addr = NULL;
 742   HeapRegion* prev_last_region = NULL;
 743 
 744   // Temporarily disable pretouching of heap pages. This interface is used
 745   // when mmap'ing archived heap data in, so pre-touching is wasted.
 746   FlagSetting fs(AlwaysPreTouch, false);
 747 
 748   // Enable archive object checking in G1MarkSweep. We have to let it know
 749   // about each archive range, so that objects in those ranges aren't marked.
 750   G1MarkSweep::enable_archive_object_check();
 751 
 752   // For each specified MemRegion range, allocate the corresponding G1
 753   // regions and mark them as archive regions. We expect the ranges in
 754   // ascending starting address order, without overlap.
 755   for (size_t i = 0; i < count; i++) {
 756     MemRegion curr_range = ranges[i];
 757     HeapWord* start_address = curr_range.start();
 758     size_t word_size = curr_range.word_size();
 759     HeapWord* last_address = curr_range.last();
 760     size_t commits = 0;
 761 
 762     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 763               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 764               p2i(start_address), p2i(last_address));
 765     guarantee(start_address > prev_last_addr,
 766               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 767               p2i(start_address), p2i(prev_last_addr));
 768     prev_last_addr = last_address;
 769 
 770     // Check for ranges that start in the same G1 region in which the previous
 771     // range ended, and adjust the start address so we don't try to allocate
 772     // the same region again. If the current range is entirely within that
 773     // region, skip it, just adjusting the recorded top.
 774     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 775     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 776       start_address = start_region->end();
 777       if (start_address > last_address) {
 778         increase_used(word_size * HeapWordSize);
 779         start_region->set_top(last_address + 1);
 780         continue;
 781       }
 782       start_region->set_top(start_address);
 783       curr_range = MemRegion(start_address, last_address + 1);
 784       start_region = _hrm.addr_to_region(start_address);
 785     }
 786 
 787     // Perform the actual region allocation, exiting if it fails.
 788     // Then note how much new space we have allocated.
 789     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 790       return false;
 791     }
 792     increase_used(word_size * HeapWordSize);
 793     if (commits != 0) {
 794       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 795                                 HeapRegion::GrainWords * HeapWordSize * commits);
 796 
 797     }
 798 
 799     // Mark each G1 region touched by the range as archive, add it to the old set,
 800     // and set the allocation context and top.
 801     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 802     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 803     prev_last_region = last_region;
 804 
 805     while (curr_region != NULL) {
 806       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 807              "Region already in use (index %u)", curr_region->hrm_index());
 808       curr_region->set_allocation_context(AllocationContext::system());
 809       curr_region->set_archive();
 810       _hr_printer.alloc(curr_region);
 811       _old_set.add(curr_region);
 812       if (curr_region != last_region) {
 813         curr_region->set_top(curr_region->end());
 814         curr_region = _hrm.next_region_in_heap(curr_region);
 815       } else {
 816         curr_region->set_top(last_address + 1);
 817         curr_region = NULL;
 818       }
 819     }
 820 
 821     // Notify mark-sweep of the archive range.
 822     G1MarkSweep::set_range_archive(curr_range, true);
 823   }
 824   return true;
 825 }
 826 
 827 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 828   assert(!is_init_completed(), "Expect to be called at JVM init time");
 829   assert(ranges != NULL, "MemRegion array NULL");
 830   assert(count != 0, "No MemRegions provided");
 831   MemRegion reserved = _hrm.reserved();
 832   HeapWord *prev_last_addr = NULL;
 833   HeapRegion* prev_last_region = NULL;
 834 
 835   // For each MemRegion, create filler objects, if needed, in the G1 regions
 836   // that contain the address range. The address range actually within the
 837   // MemRegion will not be modified. That is assumed to have been initialized
 838   // elsewhere, probably via an mmap of archived heap data.
 839   MutexLockerEx x(Heap_lock);
 840   for (size_t i = 0; i < count; i++) {
 841     HeapWord* start_address = ranges[i].start();
 842     HeapWord* last_address = ranges[i].last();
 843 
 844     assert(reserved.contains(start_address) && reserved.contains(last_address),
 845            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 846            p2i(start_address), p2i(last_address));
 847     assert(start_address > prev_last_addr,
 848            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 849            p2i(start_address), p2i(prev_last_addr));
 850 
 851     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 852     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 853     HeapWord* bottom_address = start_region->bottom();
 854 
 855     // Check for a range beginning in the same region in which the
 856     // previous one ended.
 857     if (start_region == prev_last_region) {
 858       bottom_address = prev_last_addr + 1;
 859     }
 860 
 861     // Verify that the regions were all marked as archive regions by
 862     // alloc_archive_regions.
 863     HeapRegion* curr_region = start_region;
 864     while (curr_region != NULL) {
 865       guarantee(curr_region->is_archive(),
 866                 "Expected archive region at index %u", curr_region->hrm_index());
 867       if (curr_region != last_region) {
 868         curr_region = _hrm.next_region_in_heap(curr_region);
 869       } else {
 870         curr_region = NULL;
 871       }
 872     }
 873 
 874     prev_last_addr = last_address;
 875     prev_last_region = last_region;
 876 
 877     // Fill the memory below the allocated range with dummy object(s),
 878     // if the region bottom does not match the range start, or if the previous
 879     // range ended within the same G1 region, and there is a gap.
 880     if (start_address != bottom_address) {
 881       size_t fill_size = pointer_delta(start_address, bottom_address);
 882       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 883       increase_used(fill_size * HeapWordSize);
 884     }
 885   }
 886 }
 887 
 888 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 889                                                      uint* gc_count_before_ret,
 890                                                      uint* gclocker_retry_count_ret) {
 891   assert_heap_not_locked_and_not_at_safepoint();
 892   assert(!is_humongous(word_size), "attempt_allocation() should not "
 893          "be called for humongous allocation requests");
 894 
 895   AllocationContext_t context = AllocationContext::current();
 896   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 897 
 898   if (result == NULL) {
 899     result = attempt_allocation_slow(word_size,
 900                                      context,
 901                                      gc_count_before_ret,
 902                                      gclocker_retry_count_ret);
 903   }
 904   assert_heap_not_locked();
 905   if (result != NULL) {
 906     dirty_young_block(result, word_size);
 907   }
 908   return result;
 909 }
 910 
 911 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 912   assert(!is_init_completed(), "Expect to be called at JVM init time");
 913   assert(ranges != NULL, "MemRegion array NULL");
 914   assert(count != 0, "No MemRegions provided");
 915   MemRegion reserved = _hrm.reserved();
 916   HeapWord* prev_last_addr = NULL;
 917   HeapRegion* prev_last_region = NULL;
 918   size_t size_used = 0;
 919   size_t uncommitted_regions = 0;
 920 
 921   // For each Memregion, free the G1 regions that constitute it, and
 922   // notify mark-sweep that the range is no longer to be considered 'archive.'
 923   MutexLockerEx x(Heap_lock);
 924   for (size_t i = 0; i < count; i++) {
 925     HeapWord* start_address = ranges[i].start();
 926     HeapWord* last_address = ranges[i].last();
 927 
 928     assert(reserved.contains(start_address) && reserved.contains(last_address),
 929            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 930            p2i(start_address), p2i(last_address));
 931     assert(start_address > prev_last_addr,
 932            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 933            p2i(start_address), p2i(prev_last_addr));
 934     size_used += ranges[i].byte_size();
 935     prev_last_addr = last_address;
 936 
 937     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 938     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 939 
 940     // Check for ranges that start in the same G1 region in which the previous
 941     // range ended, and adjust the start address so we don't try to free
 942     // the same region again. If the current range is entirely within that
 943     // region, skip it.
 944     if (start_region == prev_last_region) {
 945       start_address = start_region->end();
 946       if (start_address > last_address) {
 947         continue;
 948       }
 949       start_region = _hrm.addr_to_region(start_address);
 950     }
 951     prev_last_region = last_region;
 952 
 953     // After verifying that each region was marked as an archive region by
 954     // alloc_archive_regions, set it free and empty and uncommit it.
 955     HeapRegion* curr_region = start_region;
 956     while (curr_region != NULL) {
 957       guarantee(curr_region->is_archive(),
 958                 "Expected archive region at index %u", curr_region->hrm_index());
 959       uint curr_index = curr_region->hrm_index();
 960       _old_set.remove(curr_region);
 961       curr_region->set_free();
 962       curr_region->set_top(curr_region->bottom());
 963       if (curr_region != last_region) {
 964         curr_region = _hrm.next_region_in_heap(curr_region);
 965       } else {
 966         curr_region = NULL;
 967       }
 968       _hrm.shrink_at(curr_index, 1);
 969       uncommitted_regions++;
 970     }
 971 
 972     // Notify mark-sweep that this is no longer an archive range.
 973     G1MarkSweep::set_range_archive(ranges[i], false);
 974   }
 975 
 976   if (uncommitted_regions != 0) {
 977     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 978                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 979   }
 980   decrease_used(size_used);
 981 }
 982 
 983 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 984                                                         uint* gc_count_before_ret,
 985                                                         uint* gclocker_retry_count_ret) {
 986   // The structure of this method has a lot of similarities to
 987   // attempt_allocation_slow(). The reason these two were not merged
 988   // into a single one is that such a method would require several "if
 989   // allocation is not humongous do this, otherwise do that"
 990   // conditional paths which would obscure its flow. In fact, an early
 991   // version of this code did use a unified method which was harder to
 992   // follow and, as a result, it had subtle bugs that were hard to
 993   // track down. So keeping these two methods separate allows each to
 994   // be more readable. It will be good to keep these two in sync as
 995   // much as possible.
 996 
 997   assert_heap_not_locked_and_not_at_safepoint();
 998   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 999          "should only be called for humongous allocations");
1000 
1001   // Humongous objects can exhaust the heap quickly, so we should check if we
1002   // need to start a marking cycle at each humongous object allocation. We do
1003   // the check before we do the actual allocation. The reason for doing it
1004   // before the allocation is that we avoid having to keep track of the newly
1005   // allocated memory while we do a GC.
1006   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1007                                            word_size)) {
1008     collect(GCCause::_g1_humongous_allocation);
1009   }
1010 
1011   // We will loop until a) we manage to successfully perform the
1012   // allocation or b) we successfully schedule a collection which
1013   // fails to perform the allocation. b) is the only case when we'll
1014   // return NULL.
1015   HeapWord* result = NULL;
1016   for (int try_count = 1; /* we'll return */; try_count += 1) {
1017     bool should_try_gc;
1018     uint gc_count_before;
1019 
1020     {
1021       MutexLockerEx x(Heap_lock);
1022 
1023       // Given that humongous objects are not allocated in young
1024       // regions, we'll first try to do the allocation without doing a
1025       // collection hoping that there's enough space in the heap.
1026       result = humongous_obj_allocate(word_size, AllocationContext::current());
1027       if (result != NULL) {
1028         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1029         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1030         return result;
1031       }
1032 
1033       if (GCLocker::is_active_and_needs_gc()) {
1034         should_try_gc = false;
1035       } else {
1036          // The GCLocker may not be active but the GCLocker initiated
1037         // GC may not yet have been performed (GCLocker::needs_gc()
1038         // returns true). In this case we do not try this GC and
1039         // wait until the GCLocker initiated GC is performed, and
1040         // then retry the allocation.
1041         if (GCLocker::needs_gc()) {
1042           should_try_gc = false;
1043         } else {
1044           // Read the GC count while still holding the Heap_lock.
1045           gc_count_before = total_collections();
1046           should_try_gc = true;
1047         }
1048       }
1049     }
1050 
1051     if (should_try_gc) {
1052       // If we failed to allocate the humongous object, we should try to
1053       // do a collection pause (if we're allowed) in case it reclaims
1054       // enough space for the allocation to succeed after the pause.
1055 
1056       bool succeeded;
1057       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1058                                    GCCause::_g1_humongous_allocation);
1059       if (result != NULL) {
1060         assert(succeeded, "only way to get back a non-NULL result");
1061         return result;
1062       }
1063 
1064       if (succeeded) {
1065         // If we get here we successfully scheduled a collection which
1066         // failed to allocate. No point in trying to allocate
1067         // further. We'll just return NULL.
1068         MutexLockerEx x(Heap_lock);
1069         *gc_count_before_ret = total_collections();
1070         return NULL;
1071       }
1072     } else {
1073       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1074         MutexLockerEx x(Heap_lock);
1075         *gc_count_before_ret = total_collections();
1076         return NULL;
1077       }
1078       // The GCLocker is either active or the GCLocker initiated
1079       // GC has not yet been performed. Stall until it is and
1080       // then retry the allocation.
1081       GCLocker::stall_until_clear();
1082       (*gclocker_retry_count_ret) += 1;
1083     }
1084 
1085     // We can reach here if we were unsuccessful in scheduling a
1086     // collection (because another thread beat us to it) or if we were
1087     // stalled due to the GC locker. In either can we should retry the
1088     // allocation attempt in case another thread successfully
1089     // performed a collection and reclaimed enough space.  Give a
1090     // warning if we seem to be looping forever.
1091 
1092     if ((QueuedAllocationWarningCount > 0) &&
1093         (try_count % QueuedAllocationWarningCount == 0)) {
1094       warning("G1CollectedHeap::attempt_allocation_humongous() "
1095               "retries %d times", try_count);
1096     }
1097   }
1098 
1099   ShouldNotReachHere();
1100   return NULL;
1101 }
1102 
1103 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1104                                                            AllocationContext_t context,
1105                                                            bool expect_null_mutator_alloc_region) {
1106   assert_at_safepoint(true /* should_be_vm_thread */);
1107   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1108          "the current alloc region was unexpectedly found to be non-NULL");
1109 
1110   if (!is_humongous(word_size)) {
1111     return _allocator->attempt_allocation_locked(word_size, context);
1112   } else {
1113     HeapWord* result = humongous_obj_allocate(word_size, context);
1114     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1115       collector_state()->set_initiate_conc_mark_if_possible(true);
1116     }
1117     return result;
1118   }
1119 
1120   ShouldNotReachHere();
1121 }
1122 
1123 class PostMCRemSetClearClosure: public HeapRegionClosure {
1124   G1CollectedHeap* _g1h;
1125   ModRefBarrierSet* _mr_bs;
1126 public:
1127   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1128     _g1h(g1h), _mr_bs(mr_bs) {}
1129 
1130   bool doHeapRegion(HeapRegion* r) {
1131     HeapRegionRemSet* hrrs = r->rem_set();
1132 
1133     _g1h->reset_gc_time_stamps(r);
1134 
1135     if (r->is_continues_humongous()) {
1136       // We'll assert that the strong code root list and RSet is empty
1137       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1138       assert(hrrs->occupied() == 0, "RSet should be empty");
1139     } else {
1140       hrrs->clear();
1141     }
1142     // You might think here that we could clear just the cards
1143     // corresponding to the used region.  But no: if we leave a dirty card
1144     // in a region we might allocate into, then it would prevent that card
1145     // from being enqueued, and cause it to be missed.
1146     // Re: the performance cost: we shouldn't be doing full GC anyway!
1147     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1148 
1149     return false;
1150   }
1151 };
1152 
1153 void G1CollectedHeap::clear_rsets_post_compaction() {
1154   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1155   heap_region_iterate(&rs_clear);
1156 }
1157 
1158 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1159   G1CollectedHeap*   _g1h;
1160   UpdateRSOopClosure _cl;
1161 public:
1162   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1163     _cl(g1->g1_rem_set(), worker_i),
1164     _g1h(g1)
1165   { }
1166 
1167   bool doHeapRegion(HeapRegion* r) {
1168     if (!r->is_continues_humongous()) {
1169       _cl.set_from(r);
1170       r->oop_iterate(&_cl);
1171     }
1172     return false;
1173   }
1174 };
1175 
1176 class ParRebuildRSTask: public AbstractGangTask {
1177   G1CollectedHeap* _g1;
1178   HeapRegionClaimer _hrclaimer;
1179 
1180 public:
1181   ParRebuildRSTask(G1CollectedHeap* g1) :
1182       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1183 
1184   void work(uint worker_id) {
1185     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1186     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1187   }
1188 };
1189 
1190 class PostCompactionPrinterClosure: public HeapRegionClosure {
1191 private:
1192   G1HRPrinter* _hr_printer;
1193 public:
1194   bool doHeapRegion(HeapRegion* hr) {
1195     assert(!hr->is_young(), "not expecting to find young regions");
1196     _hr_printer->post_compaction(hr);
1197     return false;
1198   }
1199 
1200   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1201     : _hr_printer(hr_printer) { }
1202 };
1203 
1204 void G1CollectedHeap::print_hrm_post_compaction() {
1205   if (_hr_printer.is_active()) {
1206     PostCompactionPrinterClosure cl(hr_printer());
1207     heap_region_iterate(&cl);
1208   }
1209 
1210 }
1211 
1212 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1213                                          bool clear_all_soft_refs) {
1214   assert_at_safepoint(true /* should_be_vm_thread */);
1215 
1216   if (GCLocker::check_active_before_gc()) {
1217     return false;
1218   }
1219 
1220   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1221   gc_timer->register_gc_start();
1222 
1223   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1224   GCIdMark gc_id_mark;
1225   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1226 
1227   SvcGCMarker sgcm(SvcGCMarker::FULL);
1228   ResourceMark rm;
1229 
1230   print_heap_before_gc();
1231   trace_heap_before_gc(gc_tracer);
1232 
1233   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1234 
1235   _verifier->verify_region_sets_optional();
1236 
1237   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1238                            collector_policy()->should_clear_all_soft_refs();
1239 
1240   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1241 
1242   {
1243     IsGCActiveMark x;
1244 
1245     // Timing
1246     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1247     GCTraceCPUTime tcpu;
1248 
1249     {
1250       GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1251       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1252       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1253 
1254       G1HeapTransition heap_transition(this);
1255       g1_policy()->record_full_collection_start();
1256 
1257       // Note: When we have a more flexible GC logging framework that
1258       // allows us to add optional attributes to a GC log record we
1259       // could consider timing and reporting how long we wait in the
1260       // following two methods.
1261       wait_while_free_regions_coming();
1262       // If we start the compaction before the CM threads finish
1263       // scanning the root regions we might trip them over as we'll
1264       // be moving objects / updating references. So let's wait until
1265       // they are done. By telling them to abort, they should complete
1266       // early.
1267       _cm->root_regions()->abort();
1268       _cm->root_regions()->wait_until_scan_finished();
1269       append_secondary_free_list_if_not_empty_with_lock();
1270 
1271       gc_prologue(true);
1272       increment_total_collections(true /* full gc */);
1273       increment_old_marking_cycles_started();
1274 
1275       assert(used() == recalculate_used(), "Should be equal");
1276 
1277       _verifier->verify_before_gc();
1278 
1279       _verifier->check_bitmaps("Full GC Start");
1280       pre_full_gc_dump(gc_timer);
1281 
1282 #if defined(COMPILER2) || INCLUDE_JVMCI
1283       DerivedPointerTable::clear();
1284 #endif
1285 
1286       // Disable discovery and empty the discovered lists
1287       // for the CM ref processor.
1288       ref_processor_cm()->disable_discovery();
1289       ref_processor_cm()->abandon_partial_discovery();
1290       ref_processor_cm()->verify_no_references_recorded();
1291 
1292       // Abandon current iterations of concurrent marking and concurrent
1293       // refinement, if any are in progress. We have to do this before
1294       // wait_until_scan_finished() below.
1295       concurrent_mark()->abort();
1296 
1297       // Make sure we'll choose a new allocation region afterwards.
1298       _allocator->release_mutator_alloc_region();
1299       _allocator->abandon_gc_alloc_regions();
1300       g1_rem_set()->cleanupHRRS();
1301 
1302       // We may have added regions to the current incremental collection
1303       // set between the last GC or pause and now. We need to clear the
1304       // incremental collection set and then start rebuilding it afresh
1305       // after this full GC.
1306       abandon_collection_set(g1_policy()->inc_cset_head());
1307       g1_policy()->clear_incremental_cset();
1308       g1_policy()->stop_incremental_cset_building();
1309 
1310       tear_down_region_sets(false /* free_list_only */);
1311       collector_state()->set_gcs_are_young(true);
1312 
1313       // See the comments in g1CollectedHeap.hpp and
1314       // G1CollectedHeap::ref_processing_init() about
1315       // how reference processing currently works in G1.
1316 
1317       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1318       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1319 
1320       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1321       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1322 
1323       ref_processor_stw()->enable_discovery();
1324       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1325 
1326       // Do collection work
1327       {
1328         HandleMark hm;  // Discard invalid handles created during gc
1329         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1330       }
1331 
1332       assert(num_free_regions() == 0, "we should not have added any free regions");
1333       rebuild_region_sets(false /* free_list_only */);
1334 
1335       // Enqueue any discovered reference objects that have
1336       // not been removed from the discovered lists.
1337       ref_processor_stw()->enqueue_discovered_references();
1338 
1339 #if defined(COMPILER2) || INCLUDE_JVMCI
1340       DerivedPointerTable::update_pointers();
1341 #endif
1342 
1343       MemoryService::track_memory_usage();
1344 
1345       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1346       ref_processor_stw()->verify_no_references_recorded();
1347 
1348       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1349       ClassLoaderDataGraph::purge();
1350       MetaspaceAux::verify_metrics();
1351 
1352       // Note: since we've just done a full GC, concurrent
1353       // marking is no longer active. Therefore we need not
1354       // re-enable reference discovery for the CM ref processor.
1355       // That will be done at the start of the next marking cycle.
1356       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1357       ref_processor_cm()->verify_no_references_recorded();
1358 
1359       reset_gc_time_stamp();
1360       // Since everything potentially moved, we will clear all remembered
1361       // sets, and clear all cards.  Later we will rebuild remembered
1362       // sets. We will also reset the GC time stamps of the regions.
1363       clear_rsets_post_compaction();
1364       check_gc_time_stamps();
1365 
1366       resize_if_necessary_after_full_collection();
1367 
1368       // We should do this after we potentially resize the heap so
1369       // that all the COMMIT / UNCOMMIT events are generated before
1370       // the compaction events.
1371       print_hrm_post_compaction();
1372 
1373       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1374       if (hot_card_cache->use_cache()) {
1375         hot_card_cache->reset_card_counts();
1376         hot_card_cache->reset_hot_cache();
1377       }
1378 
1379       // Rebuild remembered sets of all regions.
1380       uint n_workers =
1381         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1382                                                 workers()->active_workers(),
1383                                                 Threads::number_of_non_daemon_threads());
1384       workers()->set_active_workers(n_workers);
1385 
1386       ParRebuildRSTask rebuild_rs_task(this);
1387       workers()->run_task(&rebuild_rs_task);
1388 
1389       // Rebuild the strong code root lists for each region
1390       rebuild_strong_code_roots();
1391 
1392       if (true) { // FIXME
1393         MetaspaceGC::compute_new_size();
1394       }
1395 
1396 #ifdef TRACESPINNING
1397       ParallelTaskTerminator::print_termination_counts();
1398 #endif
1399 
1400       // Discard all rset updates
1401       JavaThread::dirty_card_queue_set().abandon_logs();
1402       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1403 
1404       _young_list->reset_sampled_info();
1405       // At this point there should be no regions in the
1406       // entire heap tagged as young.
1407       assert(check_young_list_empty(true /* check_heap */),
1408              "young list should be empty at this point");
1409 
1410       // Update the number of full collections that have been completed.
1411       increment_old_marking_cycles_completed(false /* concurrent */);
1412 
1413       _hrm.verify_optional();
1414       _verifier->verify_region_sets_optional();
1415 
1416       _verifier->verify_after_gc();
1417 
1418       // Clear the previous marking bitmap, if needed for bitmap verification.
1419       // Note we cannot do this when we clear the next marking bitmap in
1420       // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1421       // objects marked during a full GC against the previous bitmap.
1422       // But we need to clear it before calling check_bitmaps below since
1423       // the full GC has compacted objects and updated TAMS but not updated
1424       // the prev bitmap.
1425       if (G1VerifyBitmaps) {
1426         ((G1CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1427       }
1428       _verifier->check_bitmaps("Full GC End");
1429 
1430       // Start a new incremental collection set for the next pause
1431       assert(g1_policy()->collection_set() == NULL, "must be");
1432       g1_policy()->start_incremental_cset_building();
1433 
1434       clear_cset_fast_test();
1435 
1436       _allocator->init_mutator_alloc_region();
1437 
1438       g1_policy()->record_full_collection_end();
1439 
1440       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1441       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1442       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1443       // before any GC notifications are raised.
1444       g1mm()->update_sizes();
1445 
1446       gc_epilogue(true);
1447 
1448       heap_transition.print();
1449 
1450       print_heap_after_gc();
1451       trace_heap_after_gc(gc_tracer);
1452 
1453       post_full_gc_dump(gc_timer);
1454     }
1455 
1456     gc_timer->register_gc_end();
1457     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1458   }
1459 
1460   return true;
1461 }
1462 
1463 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1464   // Currently, there is no facility in the do_full_collection(bool) API to notify
1465   // the caller that the collection did not succeed (e.g., because it was locked
1466   // out by the GC locker). So, right now, we'll ignore the return value.
1467   bool dummy = do_full_collection(true,                /* explicit_gc */
1468                                   clear_all_soft_refs);
1469 }
1470 
1471 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1472   // Include bytes that will be pre-allocated to support collections, as "used".
1473   const size_t used_after_gc = used();
1474   const size_t capacity_after_gc = capacity();
1475   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1476 
1477   // This is enforced in arguments.cpp.
1478   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1479          "otherwise the code below doesn't make sense");
1480 
1481   // We don't have floating point command-line arguments
1482   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1483   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1484   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1485   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1486 
1487   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1488   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1489 
1490   // We have to be careful here as these two calculations can overflow
1491   // 32-bit size_t's.
1492   double used_after_gc_d = (double) used_after_gc;
1493   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1494   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1495 
1496   // Let's make sure that they are both under the max heap size, which
1497   // by default will make them fit into a size_t.
1498   double desired_capacity_upper_bound = (double) max_heap_size;
1499   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1500                                     desired_capacity_upper_bound);
1501   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1502                                     desired_capacity_upper_bound);
1503 
1504   // We can now safely turn them into size_t's.
1505   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1506   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1507 
1508   // This assert only makes sense here, before we adjust them
1509   // with respect to the min and max heap size.
1510   assert(minimum_desired_capacity <= maximum_desired_capacity,
1511          "minimum_desired_capacity = " SIZE_FORMAT ", "
1512          "maximum_desired_capacity = " SIZE_FORMAT,
1513          minimum_desired_capacity, maximum_desired_capacity);
1514 
1515   // Should not be greater than the heap max size. No need to adjust
1516   // it with respect to the heap min size as it's a lower bound (i.e.,
1517   // we'll try to make the capacity larger than it, not smaller).
1518   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1519   // Should not be less than the heap min size. No need to adjust it
1520   // with respect to the heap max size as it's an upper bound (i.e.,
1521   // we'll try to make the capacity smaller than it, not greater).
1522   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1523 
1524   if (capacity_after_gc < minimum_desired_capacity) {
1525     // Don't expand unless it's significant
1526     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1527 
1528     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1529                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1530                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1531 
1532     expand(expand_bytes);
1533 
1534     // No expansion, now see if we want to shrink
1535   } else if (capacity_after_gc > maximum_desired_capacity) {
1536     // Capacity too large, compute shrinking size
1537     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1538 
1539     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1540                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1541                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1542 
1543     shrink(shrink_bytes);
1544   }
1545 }
1546 
1547 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1548                                                             AllocationContext_t context,
1549                                                             bool do_gc,
1550                                                             bool clear_all_soft_refs,
1551                                                             bool expect_null_mutator_alloc_region,
1552                                                             bool* gc_succeeded) {
1553   *gc_succeeded = true;
1554   // Let's attempt the allocation first.
1555   HeapWord* result =
1556     attempt_allocation_at_safepoint(word_size,
1557                                     context,
1558                                     expect_null_mutator_alloc_region);
1559   if (result != NULL) {
1560     assert(*gc_succeeded, "sanity");
1561     return result;
1562   }
1563 
1564   // In a G1 heap, we're supposed to keep allocation from failing by
1565   // incremental pauses.  Therefore, at least for now, we'll favor
1566   // expansion over collection.  (This might change in the future if we can
1567   // do something smarter than full collection to satisfy a failed alloc.)
1568   result = expand_and_allocate(word_size, context);
1569   if (result != NULL) {
1570     assert(*gc_succeeded, "sanity");
1571     return result;
1572   }
1573 
1574   if (do_gc) {
1575     // Expansion didn't work, we'll try to do a Full GC.
1576     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1577                                        clear_all_soft_refs);
1578   }
1579 
1580   return NULL;
1581 }
1582 
1583 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1584                                                      AllocationContext_t context,
1585                                                      bool* succeeded) {
1586   assert_at_safepoint(true /* should_be_vm_thread */);
1587 
1588   // Attempts to allocate followed by Full GC.
1589   HeapWord* result =
1590     satisfy_failed_allocation_helper(word_size,
1591                                      context,
1592                                      true,  /* do_gc */
1593                                      false, /* clear_all_soft_refs */
1594                                      false, /* expect_null_mutator_alloc_region */
1595                                      succeeded);
1596 
1597   if (result != NULL || !*succeeded) {
1598     return result;
1599   }
1600 
1601   // Attempts to allocate followed by Full GC that will collect all soft references.
1602   result = satisfy_failed_allocation_helper(word_size,
1603                                             context,
1604                                             true, /* do_gc */
1605                                             true, /* clear_all_soft_refs */
1606                                             true, /* expect_null_mutator_alloc_region */
1607                                             succeeded);
1608 
1609   if (result != NULL || !*succeeded) {
1610     return result;
1611   }
1612 
1613   // Attempts to allocate, no GC
1614   result = satisfy_failed_allocation_helper(word_size,
1615                                             context,
1616                                             false, /* do_gc */
1617                                             false, /* clear_all_soft_refs */
1618                                             true,  /* expect_null_mutator_alloc_region */
1619                                             succeeded);
1620 
1621   if (result != NULL) {
1622     assert(*succeeded, "sanity");
1623     return result;
1624   }
1625 
1626   assert(!collector_policy()->should_clear_all_soft_refs(),
1627          "Flag should have been handled and cleared prior to this point");
1628 
1629   // What else?  We might try synchronous finalization later.  If the total
1630   // space available is large enough for the allocation, then a more
1631   // complete compaction phase than we've tried so far might be
1632   // appropriate.
1633   assert(*succeeded, "sanity");
1634   return NULL;
1635 }
1636 
1637 // Attempting to expand the heap sufficiently
1638 // to support an allocation of the given "word_size".  If
1639 // successful, perform the allocation and return the address of the
1640 // allocated block, or else "NULL".
1641 
1642 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1643   assert_at_safepoint(true /* should_be_vm_thread */);
1644 
1645   _verifier->verify_region_sets_optional();
1646 
1647   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1648   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1649                             word_size * HeapWordSize);
1650 
1651 
1652   if (expand(expand_bytes)) {
1653     _hrm.verify_optional();
1654     _verifier->verify_region_sets_optional();
1655     return attempt_allocation_at_safepoint(word_size,
1656                                            context,
1657                                            false /* expect_null_mutator_alloc_region */);
1658   }
1659   return NULL;
1660 }
1661 
1662 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1663   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1664   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1665                                        HeapRegion::GrainBytes);
1666 
1667   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1668                             expand_bytes, aligned_expand_bytes);
1669 
1670   if (is_maximal_no_gc()) {
1671     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1672     return false;
1673   }
1674 
1675   double expand_heap_start_time_sec = os::elapsedTime();
1676   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1677   assert(regions_to_expand > 0, "Must expand by at least one region");
1678 
1679   uint expanded_by = _hrm.expand_by(regions_to_expand);
1680   if (expand_time_ms != NULL) {
1681     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1682   }
1683 
1684   if (expanded_by > 0) {
1685     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1686     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1687     g1_policy()->record_new_heap_size(num_regions());
1688   } else {
1689     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1690 
1691     // The expansion of the virtual storage space was unsuccessful.
1692     // Let's see if it was because we ran out of swap.
1693     if (G1ExitOnExpansionFailure &&
1694         _hrm.available() >= regions_to_expand) {
1695       // We had head room...
1696       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1697     }
1698   }
1699   return regions_to_expand > 0;
1700 }
1701 
1702 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1703   size_t aligned_shrink_bytes =
1704     ReservedSpace::page_align_size_down(shrink_bytes);
1705   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1706                                          HeapRegion::GrainBytes);
1707   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1708 
1709   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1710   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1711 
1712 
1713   log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1714                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1715   if (num_regions_removed > 0) {
1716     g1_policy()->record_new_heap_size(num_regions());
1717   } else {
1718     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1719   }
1720 }
1721 
1722 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1723   _verifier->verify_region_sets_optional();
1724 
1725   // We should only reach here at the end of a Full GC which means we
1726   // should not not be holding to any GC alloc regions. The method
1727   // below will make sure of that and do any remaining clean up.
1728   _allocator->abandon_gc_alloc_regions();
1729 
1730   // Instead of tearing down / rebuilding the free lists here, we
1731   // could instead use the remove_all_pending() method on free_list to
1732   // remove only the ones that we need to remove.
1733   tear_down_region_sets(true /* free_list_only */);
1734   shrink_helper(shrink_bytes);
1735   rebuild_region_sets(true /* free_list_only */);
1736 
1737   _hrm.verify_optional();
1738   _verifier->verify_region_sets_optional();
1739 }
1740 
1741 // Public methods.
1742 
1743 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1744   CollectedHeap(),
1745   _g1_policy(policy_),
1746   _dirty_card_queue_set(false),
1747   _is_alive_closure_cm(this),
1748   _is_alive_closure_stw(this),
1749   _ref_processor_cm(NULL),
1750   _ref_processor_stw(NULL),
1751   _bot(NULL),
1752   _cg1r(NULL),
1753   _g1mm(NULL),
1754   _refine_cte_cl(NULL),
1755   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1756   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1757   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1758   _humongous_reclaim_candidates(),
1759   _has_humongous_reclaim_candidates(false),
1760   _archive_allocator(NULL),
1761   _free_regions_coming(false),
1762   _young_list(new YoungList(this)),
1763   _gc_time_stamp(0),
1764   _summary_bytes_used(0),
1765   _survivor_evac_stats(YoungPLABSize, PLABWeight),
1766   _old_evac_stats(OldPLABSize, PLABWeight),
1767   _expand_heap_after_alloc_failure(true),
1768   _old_marking_cycles_started(0),
1769   _old_marking_cycles_completed(0),
1770   _heap_summary_sent(false),
1771   _in_cset_fast_test(),
1772   _dirty_cards_region_list(NULL),
1773   _worker_cset_start_region(NULL),
1774   _worker_cset_start_region_time_stamp(NULL),
1775   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1776   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1777   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1778   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1779 
1780   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1781                           /* are_GC_task_threads */true,
1782                           /* are_ConcurrentGC_threads */false);
1783   _workers->initialize_workers();
1784   _verifier = new G1HeapVerifier(this);
1785 
1786   _allocator = G1Allocator::create_allocator(this);
1787   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1788 
1789   // Override the default _filler_array_max_size so that no humongous filler
1790   // objects are created.
1791   _filler_array_max_size = _humongous_object_threshold_in_words;
1792 
1793   uint n_queues = ParallelGCThreads;
1794   _task_queues = new RefToScanQueueSet(n_queues);
1795 
1796   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1797   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1798   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1799 
1800   for (uint i = 0; i < n_queues; i++) {
1801     RefToScanQueue* q = new RefToScanQueue();
1802     q->initialize();
1803     _task_queues->register_queue(i, q);
1804     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1805   }
1806   clear_cset_start_regions();
1807 
1808   // Initialize the G1EvacuationFailureALot counters and flags.
1809   NOT_PRODUCT(reset_evacuation_should_fail();)
1810 
1811   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1812 }
1813 
1814 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1815                                                                  size_t size,
1816                                                                  size_t translation_factor) {
1817   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1818   // Allocate a new reserved space, preferring to use large pages.
1819   ReservedSpace rs(size, preferred_page_size);
1820   G1RegionToSpaceMapper* result  =
1821     G1RegionToSpaceMapper::create_mapper(rs,
1822                                          size,
1823                                          rs.alignment(),
1824                                          HeapRegion::GrainBytes,
1825                                          translation_factor,
1826                                          mtGC);
1827   if (TracePageSizes) {
1828     tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1829                   description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1830   }
1831   return result;
1832 }
1833 
1834 jint G1CollectedHeap::initialize() {
1835   CollectedHeap::pre_initialize();
1836   os::enable_vtime();
1837 
1838   // Necessary to satisfy locking discipline assertions.
1839 
1840   MutexLocker x(Heap_lock);
1841 
1842   // While there are no constraints in the GC code that HeapWordSize
1843   // be any particular value, there are multiple other areas in the
1844   // system which believe this to be true (e.g. oop->object_size in some
1845   // cases incorrectly returns the size in wordSize units rather than
1846   // HeapWordSize).
1847   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1848 
1849   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1850   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1851   size_t heap_alignment = collector_policy()->heap_alignment();
1852 
1853   // Ensure that the sizes are properly aligned.
1854   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1855   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1856   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1857 
1858   _refine_cte_cl = new RefineCardTableEntryClosure();
1859 
1860   jint ecode = JNI_OK;
1861   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1862   if (_cg1r == NULL) {
1863     return ecode;
1864   }
1865 
1866   // Reserve the maximum.
1867 
1868   // When compressed oops are enabled, the preferred heap base
1869   // is calculated by subtracting the requested size from the
1870   // 32Gb boundary and using the result as the base address for
1871   // heap reservation. If the requested size is not aligned to
1872   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1873   // into the ReservedHeapSpace constructor) then the actual
1874   // base of the reserved heap may end up differing from the
1875   // address that was requested (i.e. the preferred heap base).
1876   // If this happens then we could end up using a non-optimal
1877   // compressed oops mode.
1878 
1879   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1880                                                  heap_alignment);
1881 
1882   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1883 
1884   // Create the barrier set for the entire reserved region.
1885   G1SATBCardTableLoggingModRefBS* bs
1886     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1887   bs->initialize();
1888   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1889   set_barrier_set(bs);
1890 
1891   // Also create a G1 rem set.
1892   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1893 
1894   // Carve out the G1 part of the heap.
1895   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1896   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1897   G1RegionToSpaceMapper* heap_storage =
1898     G1RegionToSpaceMapper::create_mapper(g1_rs,
1899                                          g1_rs.size(),
1900                                          page_size,
1901                                          HeapRegion::GrainBytes,
1902                                          1,
1903                                          mtJavaHeap);
1904   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1905                        max_byte_size, page_size,
1906                        heap_rs.base(),
1907                        heap_rs.size());
1908   heap_storage->set_mapping_changed_listener(&_listener);
1909 
1910   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1911   G1RegionToSpaceMapper* bot_storage =
1912     create_aux_memory_mapper("Block offset table",
1913                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1914                              G1BlockOffsetTable::heap_map_factor());
1915 
1916   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1917   G1RegionToSpaceMapper* cardtable_storage =
1918     create_aux_memory_mapper("Card table",
1919                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1920                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1921 
1922   G1RegionToSpaceMapper* card_counts_storage =
1923     create_aux_memory_mapper("Card counts table",
1924                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1925                              G1CardCounts::heap_map_factor());
1926 
1927   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1928   G1RegionToSpaceMapper* prev_bitmap_storage =
1929     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1930   G1RegionToSpaceMapper* next_bitmap_storage =
1931     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1932 
1933   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1934   g1_barrier_set()->initialize(cardtable_storage);
1935    // Do later initialization work for concurrent refinement.
1936   _cg1r->init(card_counts_storage);
1937 
1938   // 6843694 - ensure that the maximum region index can fit
1939   // in the remembered set structures.
1940   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1941   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1942 
1943   G1RemSet::initialize(max_regions());
1944 
1945   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1946   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1947   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1948             "too many cards per region");
1949 
1950   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1951 
1952   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1953 
1954   {
1955     HeapWord* start = _hrm.reserved().start();
1956     HeapWord* end = _hrm.reserved().end();
1957     size_t granularity = HeapRegion::GrainBytes;
1958 
1959     _in_cset_fast_test.initialize(start, end, granularity);
1960     _humongous_reclaim_candidates.initialize(start, end, granularity);
1961   }
1962 
1963   // Create the G1ConcurrentMark data structure and thread.
1964   // (Must do this late, so that "max_regions" is defined.)
1965   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1966   if (_cm == NULL || !_cm->completed_initialization()) {
1967     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1968     return JNI_ENOMEM;
1969   }
1970   _cmThread = _cm->cmThread();
1971 
1972   // Now expand into the initial heap size.
1973   if (!expand(init_byte_size)) {
1974     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1975     return JNI_ENOMEM;
1976   }
1977 
1978   // Perform any initialization actions delegated to the policy.
1979   g1_policy()->init();
1980 
1981   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1982                                                SATB_Q_FL_lock,
1983                                                G1SATBProcessCompletedThreshold,
1984                                                Shared_SATB_Q_lock);
1985 
1986   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1987                                                 DirtyCardQ_CBL_mon,
1988                                                 DirtyCardQ_FL_lock,
1989                                                 concurrent_g1_refine()->yellow_zone(),
1990                                                 concurrent_g1_refine()->red_zone(),
1991                                                 Shared_DirtyCardQ_lock,
1992                                                 NULL,  // fl_owner
1993                                                 true); // init_free_ids
1994 
1995   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1996                                     DirtyCardQ_CBL_mon,
1997                                     DirtyCardQ_FL_lock,
1998                                     -1, // never trigger processing
1999                                     -1, // no limit on length
2000                                     Shared_DirtyCardQ_lock,
2001                                     &JavaThread::dirty_card_queue_set());
2002 
2003   // Here we allocate the dummy HeapRegion that is required by the
2004   // G1AllocRegion class.
2005   HeapRegion* dummy_region = _hrm.get_dummy_region();
2006 
2007   // We'll re-use the same region whether the alloc region will
2008   // require BOT updates or not and, if it doesn't, then a non-young
2009   // region will complain that it cannot support allocations without
2010   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2011   dummy_region->set_eden();
2012   // Make sure it's full.
2013   dummy_region->set_top(dummy_region->end());
2014   G1AllocRegion::setup(this, dummy_region);
2015 
2016   _allocator->init_mutator_alloc_region();
2017 
2018   // Do create of the monitoring and management support so that
2019   // values in the heap have been properly initialized.
2020   _g1mm = new G1MonitoringSupport(this);
2021 
2022   G1StringDedup::initialize();
2023 
2024   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2025   for (uint i = 0; i < ParallelGCThreads; i++) {
2026     new (&_preserved_objs[i]) OopAndMarkOopStack();
2027   }
2028 
2029   return JNI_OK;
2030 }
2031 
2032 void G1CollectedHeap::stop() {
2033   // Stop all concurrent threads. We do this to make sure these threads
2034   // do not continue to execute and access resources (e.g. logging)
2035   // that are destroyed during shutdown.
2036   _cg1r->stop();
2037   _cmThread->stop();
2038   if (G1StringDedup::is_enabled()) {
2039     G1StringDedup::stop();
2040   }
2041 }
2042 
2043 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2044   return HeapRegion::max_region_size();
2045 }
2046 
2047 void G1CollectedHeap::post_initialize() {
2048   CollectedHeap::post_initialize();
2049   ref_processing_init();
2050 }
2051 
2052 void G1CollectedHeap::ref_processing_init() {
2053   // Reference processing in G1 currently works as follows:
2054   //
2055   // * There are two reference processor instances. One is
2056   //   used to record and process discovered references
2057   //   during concurrent marking; the other is used to
2058   //   record and process references during STW pauses
2059   //   (both full and incremental).
2060   // * Both ref processors need to 'span' the entire heap as
2061   //   the regions in the collection set may be dotted around.
2062   //
2063   // * For the concurrent marking ref processor:
2064   //   * Reference discovery is enabled at initial marking.
2065   //   * Reference discovery is disabled and the discovered
2066   //     references processed etc during remarking.
2067   //   * Reference discovery is MT (see below).
2068   //   * Reference discovery requires a barrier (see below).
2069   //   * Reference processing may or may not be MT
2070   //     (depending on the value of ParallelRefProcEnabled
2071   //     and ParallelGCThreads).
2072   //   * A full GC disables reference discovery by the CM
2073   //     ref processor and abandons any entries on it's
2074   //     discovered lists.
2075   //
2076   // * For the STW processor:
2077   //   * Non MT discovery is enabled at the start of a full GC.
2078   //   * Processing and enqueueing during a full GC is non-MT.
2079   //   * During a full GC, references are processed after marking.
2080   //
2081   //   * Discovery (may or may not be MT) is enabled at the start
2082   //     of an incremental evacuation pause.
2083   //   * References are processed near the end of a STW evacuation pause.
2084   //   * For both types of GC:
2085   //     * Discovery is atomic - i.e. not concurrent.
2086   //     * Reference discovery will not need a barrier.
2087 
2088   MemRegion mr = reserved_region();
2089 
2090   // Concurrent Mark ref processor
2091   _ref_processor_cm =
2092     new ReferenceProcessor(mr,    // span
2093                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2094                                 // mt processing
2095                            ParallelGCThreads,
2096                                 // degree of mt processing
2097                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2098                                 // mt discovery
2099                            MAX2(ParallelGCThreads, ConcGCThreads),
2100                                 // degree of mt discovery
2101                            false,
2102                                 // Reference discovery is not atomic
2103                            &_is_alive_closure_cm);
2104                                 // is alive closure
2105                                 // (for efficiency/performance)
2106 
2107   // STW ref processor
2108   _ref_processor_stw =
2109     new ReferenceProcessor(mr,    // span
2110                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2111                                 // mt processing
2112                            ParallelGCThreads,
2113                                 // degree of mt processing
2114                            (ParallelGCThreads > 1),
2115                                 // mt discovery
2116                            ParallelGCThreads,
2117                                 // degree of mt discovery
2118                            true,
2119                                 // Reference discovery is atomic
2120                            &_is_alive_closure_stw);
2121                                 // is alive closure
2122                                 // (for efficiency/performance)
2123 }
2124 
2125 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2126   return g1_policy();
2127 }
2128 
2129 size_t G1CollectedHeap::capacity() const {
2130   return _hrm.length() * HeapRegion::GrainBytes;
2131 }
2132 
2133 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2134   hr->reset_gc_time_stamp();
2135 }
2136 
2137 #ifndef PRODUCT
2138 
2139 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2140 private:
2141   unsigned _gc_time_stamp;
2142   bool _failures;
2143 
2144 public:
2145   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2146     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2147 
2148   virtual bool doHeapRegion(HeapRegion* hr) {
2149     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2150     if (_gc_time_stamp != region_gc_time_stamp) {
2151       log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2152                            region_gc_time_stamp, _gc_time_stamp);
2153       _failures = true;
2154     }
2155     return false;
2156   }
2157 
2158   bool failures() { return _failures; }
2159 };
2160 
2161 void G1CollectedHeap::check_gc_time_stamps() {
2162   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2163   heap_region_iterate(&cl);
2164   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2165 }
2166 #endif // PRODUCT
2167 
2168 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2169   _cg1r->hot_card_cache()->drain(cl, worker_i);
2170 }
2171 
2172 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2173   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2174   size_t n_completed_buffers = 0;
2175   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2176     n_completed_buffers++;
2177   }
2178   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2179   dcqs.clear_n_completed_buffers();
2180   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2181 }
2182 
2183 // Computes the sum of the storage used by the various regions.
2184 size_t G1CollectedHeap::used() const {
2185   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2186   if (_archive_allocator != NULL) {
2187     result += _archive_allocator->used();
2188   }
2189   return result;
2190 }
2191 
2192 size_t G1CollectedHeap::used_unlocked() const {
2193   return _summary_bytes_used;
2194 }
2195 
2196 class SumUsedClosure: public HeapRegionClosure {
2197   size_t _used;
2198 public:
2199   SumUsedClosure() : _used(0) {}
2200   bool doHeapRegion(HeapRegion* r) {
2201     _used += r->used();
2202     return false;
2203   }
2204   size_t result() { return _used; }
2205 };
2206 
2207 size_t G1CollectedHeap::recalculate_used() const {
2208   double recalculate_used_start = os::elapsedTime();
2209 
2210   SumUsedClosure blk;
2211   heap_region_iterate(&blk);
2212 
2213   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2214   return blk.result();
2215 }
2216 
2217 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2218   switch (cause) {
2219     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2220     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2221     case GCCause::_update_allocation_context_stats_inc: return true;
2222     case GCCause::_wb_conc_mark:                        return true;
2223     default :                                           return false;
2224   }
2225 }
2226 
2227 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2228   switch (cause) {
2229     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2230     case GCCause::_g1_humongous_allocation: return true;
2231     default:                                return is_user_requested_concurrent_full_gc(cause);
2232   }
2233 }
2234 
2235 #ifndef PRODUCT
2236 void G1CollectedHeap::allocate_dummy_regions() {
2237   // Let's fill up most of the region
2238   size_t word_size = HeapRegion::GrainWords - 1024;
2239   // And as a result the region we'll allocate will be humongous.
2240   guarantee(is_humongous(word_size), "sanity");
2241 
2242   // _filler_array_max_size is set to humongous object threshold
2243   // but temporarily change it to use CollectedHeap::fill_with_object().
2244   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2245 
2246   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2247     // Let's use the existing mechanism for the allocation
2248     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2249                                                  AllocationContext::system());
2250     if (dummy_obj != NULL) {
2251       MemRegion mr(dummy_obj, word_size);
2252       CollectedHeap::fill_with_object(mr);
2253     } else {
2254       // If we can't allocate once, we probably cannot allocate
2255       // again. Let's get out of the loop.
2256       break;
2257     }
2258   }
2259 }
2260 #endif // !PRODUCT
2261 
2262 void G1CollectedHeap::increment_old_marking_cycles_started() {
2263   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2264          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2265          "Wrong marking cycle count (started: %d, completed: %d)",
2266          _old_marking_cycles_started, _old_marking_cycles_completed);
2267 
2268   _old_marking_cycles_started++;
2269 }
2270 
2271 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2272   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2273 
2274   // We assume that if concurrent == true, then the caller is a
2275   // concurrent thread that was joined the Suspendible Thread
2276   // Set. If there's ever a cheap way to check this, we should add an
2277   // assert here.
2278 
2279   // Given that this method is called at the end of a Full GC or of a
2280   // concurrent cycle, and those can be nested (i.e., a Full GC can
2281   // interrupt a concurrent cycle), the number of full collections
2282   // completed should be either one (in the case where there was no
2283   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2284   // behind the number of full collections started.
2285 
2286   // This is the case for the inner caller, i.e. a Full GC.
2287   assert(concurrent ||
2288          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2289          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2290          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2291          "is inconsistent with _old_marking_cycles_completed = %u",
2292          _old_marking_cycles_started, _old_marking_cycles_completed);
2293 
2294   // This is the case for the outer caller, i.e. the concurrent cycle.
2295   assert(!concurrent ||
2296          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2297          "for outer caller (concurrent cycle): "
2298          "_old_marking_cycles_started = %u "
2299          "is inconsistent with _old_marking_cycles_completed = %u",
2300          _old_marking_cycles_started, _old_marking_cycles_completed);
2301 
2302   _old_marking_cycles_completed += 1;
2303 
2304   // We need to clear the "in_progress" flag in the CM thread before
2305   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2306   // is set) so that if a waiter requests another System.gc() it doesn't
2307   // incorrectly see that a marking cycle is still in progress.
2308   if (concurrent) {
2309     _cmThread->set_idle();
2310   }
2311 
2312   // This notify_all() will ensure that a thread that called
2313   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2314   // and it's waiting for a full GC to finish will be woken up. It is
2315   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2316   FullGCCount_lock->notify_all();
2317 }
2318 
2319 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2320   GCIdMarkAndRestore conc_gc_id_mark;
2321   collector_state()->set_concurrent_cycle_started(true);
2322   _gc_timer_cm->register_gc_start(start_time);
2323 
2324   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2325   trace_heap_before_gc(_gc_tracer_cm);
2326   _cmThread->set_gc_id(GCId::current());
2327 }
2328 
2329 void G1CollectedHeap::register_concurrent_cycle_end() {
2330   if (collector_state()->concurrent_cycle_started()) {
2331     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2332     if (_cm->has_aborted()) {
2333       _gc_tracer_cm->report_concurrent_mode_failure();
2334     }
2335 
2336     _gc_timer_cm->register_gc_end();
2337     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2338 
2339     // Clear state variables to prepare for the next concurrent cycle.
2340     collector_state()->set_concurrent_cycle_started(false);
2341     _heap_summary_sent = false;
2342   }
2343 }
2344 
2345 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2346   if (collector_state()->concurrent_cycle_started()) {
2347     // This function can be called when:
2348     //  the cleanup pause is run
2349     //  the concurrent cycle is aborted before the cleanup pause.
2350     //  the concurrent cycle is aborted after the cleanup pause,
2351     //   but before the concurrent cycle end has been registered.
2352     // Make sure that we only send the heap information once.
2353     if (!_heap_summary_sent) {
2354       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2355       trace_heap_after_gc(_gc_tracer_cm);
2356       _heap_summary_sent = true;
2357     }
2358   }
2359 }
2360 
2361 void G1CollectedHeap::collect(GCCause::Cause cause) {
2362   assert_heap_not_locked();
2363 
2364   uint gc_count_before;
2365   uint old_marking_count_before;
2366   uint full_gc_count_before;
2367   bool retry_gc;
2368 
2369   do {
2370     retry_gc = false;
2371 
2372     {
2373       MutexLocker ml(Heap_lock);
2374 
2375       // Read the GC count while holding the Heap_lock
2376       gc_count_before = total_collections();
2377       full_gc_count_before = total_full_collections();
2378       old_marking_count_before = _old_marking_cycles_started;
2379     }
2380 
2381     if (should_do_concurrent_full_gc(cause)) {
2382       // Schedule an initial-mark evacuation pause that will start a
2383       // concurrent cycle. We're setting word_size to 0 which means that
2384       // we are not requesting a post-GC allocation.
2385       VM_G1IncCollectionPause op(gc_count_before,
2386                                  0,     /* word_size */
2387                                  true,  /* should_initiate_conc_mark */
2388                                  g1_policy()->max_pause_time_ms(),
2389                                  cause);
2390       op.set_allocation_context(AllocationContext::current());
2391 
2392       VMThread::execute(&op);
2393       if (!op.pause_succeeded()) {
2394         if (old_marking_count_before == _old_marking_cycles_started) {
2395           retry_gc = op.should_retry_gc();
2396         } else {
2397           // A Full GC happened while we were trying to schedule the
2398           // initial-mark GC. No point in starting a new cycle given
2399           // that the whole heap was collected anyway.
2400         }
2401 
2402         if (retry_gc) {
2403           if (GCLocker::is_active_and_needs_gc()) {
2404             GCLocker::stall_until_clear();
2405           }
2406         }
2407       }
2408     } else {
2409       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2410           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2411 
2412         // Schedule a standard evacuation pause. We're setting word_size
2413         // to 0 which means that we are not requesting a post-GC allocation.
2414         VM_G1IncCollectionPause op(gc_count_before,
2415                                    0,     /* word_size */
2416                                    false, /* should_initiate_conc_mark */
2417                                    g1_policy()->max_pause_time_ms(),
2418                                    cause);
2419         VMThread::execute(&op);
2420       } else {
2421         // Schedule a Full GC.
2422         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2423         VMThread::execute(&op);
2424       }
2425     }
2426   } while (retry_gc);
2427 }
2428 
2429 bool G1CollectedHeap::is_in(const void* p) const {
2430   if (_hrm.reserved().contains(p)) {
2431     // Given that we know that p is in the reserved space,
2432     // heap_region_containing() should successfully
2433     // return the containing region.
2434     HeapRegion* hr = heap_region_containing(p);
2435     return hr->is_in(p);
2436   } else {
2437     return false;
2438   }
2439 }
2440 
2441 #ifdef ASSERT
2442 bool G1CollectedHeap::is_in_exact(const void* p) const {
2443   bool contains = reserved_region().contains(p);
2444   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2445   if (contains && available) {
2446     return true;
2447   } else {
2448     return false;
2449   }
2450 }
2451 #endif
2452 
2453 bool G1CollectedHeap::obj_in_cs(oop obj) {
2454   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2455   return r != NULL && r->in_collection_set();
2456 }
2457 
2458 // Iteration functions.
2459 
2460 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2461 
2462 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2463   ExtendedOopClosure* _cl;
2464 public:
2465   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2466   bool doHeapRegion(HeapRegion* r) {
2467     if (!r->is_continues_humongous()) {
2468       r->oop_iterate(_cl);
2469     }
2470     return false;
2471   }
2472 };
2473 
2474 // Iterates an ObjectClosure over all objects within a HeapRegion.
2475 
2476 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2477   ObjectClosure* _cl;
2478 public:
2479   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2480   bool doHeapRegion(HeapRegion* r) {
2481     if (!r->is_continues_humongous()) {
2482       r->object_iterate(_cl);
2483     }
2484     return false;
2485   }
2486 };
2487 
2488 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2489   IterateObjectClosureRegionClosure blk(cl);
2490   heap_region_iterate(&blk);
2491 }
2492 
2493 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2494   _hrm.iterate(cl);
2495 }
2496 
2497 void
2498 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2499                                          uint worker_id,
2500                                          HeapRegionClaimer *hrclaimer,
2501                                          bool concurrent) const {
2502   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2503 }
2504 
2505 // Clear the cached CSet starting regions and (more importantly)
2506 // the time stamps. Called when we reset the GC time stamp.
2507 void G1CollectedHeap::clear_cset_start_regions() {
2508   assert(_worker_cset_start_region != NULL, "sanity");
2509   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2510 
2511   for (uint i = 0; i < ParallelGCThreads; i++) {
2512     _worker_cset_start_region[i] = NULL;
2513     _worker_cset_start_region_time_stamp[i] = 0;
2514   }
2515 }
2516 
2517 // Given the id of a worker, obtain or calculate a suitable
2518 // starting region for iterating over the current collection set.
2519 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2520   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2521 
2522   HeapRegion* result = NULL;
2523   unsigned gc_time_stamp = get_gc_time_stamp();
2524 
2525   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2526     // Cached starting region for current worker was set
2527     // during the current pause - so it's valid.
2528     // Note: the cached starting heap region may be NULL
2529     // (when the collection set is empty).
2530     result = _worker_cset_start_region[worker_i];
2531     assert(result == NULL || result->in_collection_set(), "sanity");
2532     return result;
2533   }
2534 
2535   // The cached entry was not valid so let's calculate
2536   // a suitable starting heap region for this worker.
2537 
2538   // We want the parallel threads to start their collection
2539   // set iteration at different collection set regions to
2540   // avoid contention.
2541   // If we have:
2542   //          n collection set regions
2543   //          p threads
2544   // Then thread t will start at region floor ((t * n) / p)
2545 
2546   result = g1_policy()->collection_set();
2547   uint cs_size = g1_policy()->cset_region_length();
2548   uint active_workers = workers()->active_workers();
2549 
2550   uint end_ind   = (cs_size * worker_i) / active_workers;
2551   uint start_ind = 0;
2552 
2553   if (worker_i > 0 &&
2554       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2555     // Previous workers starting region is valid
2556     // so let's iterate from there
2557     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2558     OrderAccess::loadload();
2559     result = _worker_cset_start_region[worker_i - 1];
2560   }
2561 
2562   for (uint i = start_ind; i < end_ind; i++) {
2563     result = result->next_in_collection_set();
2564   }
2565 
2566   // Note: the calculated starting heap region may be NULL
2567   // (when the collection set is empty).
2568   assert(result == NULL || result->in_collection_set(), "sanity");
2569   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2570          "should be updated only once per pause");
2571   _worker_cset_start_region[worker_i] = result;
2572   OrderAccess::storestore();
2573   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2574   return result;
2575 }
2576 
2577 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2578   HeapRegion* r = g1_policy()->collection_set();
2579   while (r != NULL) {
2580     HeapRegion* next = r->next_in_collection_set();
2581     if (cl->doHeapRegion(r)) {
2582       cl->incomplete();
2583       return;
2584     }
2585     r = next;
2586   }
2587 }
2588 
2589 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2590                                                   HeapRegionClosure *cl) {
2591   if (r == NULL) {
2592     // The CSet is empty so there's nothing to do.
2593     return;
2594   }
2595 
2596   assert(r->in_collection_set(),
2597          "Start region must be a member of the collection set.");
2598   HeapRegion* cur = r;
2599   while (cur != NULL) {
2600     HeapRegion* next = cur->next_in_collection_set();
2601     if (cl->doHeapRegion(cur) && false) {
2602       cl->incomplete();
2603       return;
2604     }
2605     cur = next;
2606   }
2607   cur = g1_policy()->collection_set();
2608   while (cur != r) {
2609     HeapRegion* next = cur->next_in_collection_set();
2610     if (cl->doHeapRegion(cur) && false) {
2611       cl->incomplete();
2612       return;
2613     }
2614     cur = next;
2615   }
2616 }
2617 
2618 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2619   HeapRegion* result = _hrm.next_region_in_heap(from);
2620   while (result != NULL && result->is_pinned()) {
2621     result = _hrm.next_region_in_heap(result);
2622   }
2623   return result;
2624 }
2625 
2626 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2627   HeapRegion* hr = heap_region_containing(addr);
2628   return hr->block_start(addr);
2629 }
2630 
2631 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2632   HeapRegion* hr = heap_region_containing(addr);
2633   return hr->block_size(addr);
2634 }
2635 
2636 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2637   HeapRegion* hr = heap_region_containing(addr);
2638   return hr->block_is_obj(addr);
2639 }
2640 
2641 bool G1CollectedHeap::supports_tlab_allocation() const {
2642   return true;
2643 }
2644 
2645 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2646   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2647 }
2648 
2649 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2650   return young_list()->eden_used_bytes();
2651 }
2652 
2653 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2654 // must be equal to the humongous object limit.
2655 size_t G1CollectedHeap::max_tlab_size() const {
2656   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2657 }
2658 
2659 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2660   AllocationContext_t context = AllocationContext::current();
2661   return _allocator->unsafe_max_tlab_alloc(context);
2662 }
2663 
2664 size_t G1CollectedHeap::max_capacity() const {
2665   return _hrm.reserved().byte_size();
2666 }
2667 
2668 jlong G1CollectedHeap::millis_since_last_gc() {
2669   // assert(false, "NYI");
2670   return 0;
2671 }
2672 
2673 void G1CollectedHeap::prepare_for_verify() {
2674   _verifier->prepare_for_verify();
2675 }
2676 
2677 void G1CollectedHeap::verify(VerifyOption vo) {
2678   _verifier->verify(vo);
2679 }
2680 
2681 class PrintRegionClosure: public HeapRegionClosure {
2682   outputStream* _st;
2683 public:
2684   PrintRegionClosure(outputStream* st) : _st(st) {}
2685   bool doHeapRegion(HeapRegion* r) {
2686     r->print_on(_st);
2687     return false;
2688   }
2689 };
2690 
2691 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2692                                        const HeapRegion* hr,
2693                                        const VerifyOption vo) const {
2694   switch (vo) {
2695   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2696   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2697   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2698   default:                            ShouldNotReachHere();
2699   }
2700   return false; // keep some compilers happy
2701 }
2702 
2703 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2704                                        const VerifyOption vo) const {
2705   switch (vo) {
2706   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2707   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2708   case VerifyOption_G1UseMarkWord: {
2709     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2710     return !obj->is_gc_marked() && !hr->is_archive();
2711   }
2712   default:                            ShouldNotReachHere();
2713   }
2714   return false; // keep some compilers happy
2715 }
2716 
2717 void G1CollectedHeap::print_on(outputStream* st) const {
2718   st->print(" %-20s", "garbage-first heap");
2719   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2720             capacity()/K, used_unlocked()/K);
2721   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2722             p2i(_hrm.reserved().start()),
2723             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2724             p2i(_hrm.reserved().end()));
2725   st->cr();
2726   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2727   uint young_regions = _young_list->length();
2728   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2729             (size_t) young_regions * HeapRegion::GrainBytes / K);
2730   uint survivor_regions = g1_policy()->recorded_survivor_regions();
2731   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2732             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2733   st->cr();
2734   MetaspaceAux::print_on(st);
2735 }
2736 
2737 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2738   print_on(st);
2739 
2740   // Print the per-region information.
2741   st->cr();
2742   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2743                "HS=humongous(starts), HC=humongous(continues), "
2744                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2745                "AC=allocation context, "
2746                "TAMS=top-at-mark-start (previous, next)");
2747   PrintRegionClosure blk(st);
2748   heap_region_iterate(&blk);
2749 }
2750 
2751 void G1CollectedHeap::print_on_error(outputStream* st) const {
2752   this->CollectedHeap::print_on_error(st);
2753 
2754   if (_cm != NULL) {
2755     st->cr();
2756     _cm->print_on_error(st);
2757   }
2758 }
2759 
2760 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2761   workers()->print_worker_threads_on(st);
2762   _cmThread->print_on(st);
2763   st->cr();
2764   _cm->print_worker_threads_on(st);
2765   _cg1r->print_worker_threads_on(st);
2766   if (G1StringDedup::is_enabled()) {
2767     G1StringDedup::print_worker_threads_on(st);
2768   }
2769 }
2770 
2771 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2772   workers()->threads_do(tc);
2773   tc->do_thread(_cmThread);
2774   _cg1r->threads_do(tc);
2775   if (G1StringDedup::is_enabled()) {
2776     G1StringDedup::threads_do(tc);
2777   }
2778 }
2779 
2780 void G1CollectedHeap::print_tracing_info() const {
2781   // We'll overload this to mean "trace GC pause statistics."
2782   if (TraceYoungGenTime || TraceOldGenTime) {
2783     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2784     // to that.
2785     g1_policy()->print_tracing_info();
2786   }
2787   g1_rem_set()->print_summary_info();
2788   concurrent_mark()->print_summary_info();
2789   g1_policy()->print_yg_surv_rate_info();
2790 }
2791 
2792 #ifndef PRODUCT
2793 // Helpful for debugging RSet issues.
2794 
2795 class PrintRSetsClosure : public HeapRegionClosure {
2796 private:
2797   const char* _msg;
2798   size_t _occupied_sum;
2799 
2800 public:
2801   bool doHeapRegion(HeapRegion* r) {
2802     HeapRegionRemSet* hrrs = r->rem_set();
2803     size_t occupied = hrrs->occupied();
2804     _occupied_sum += occupied;
2805 
2806     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2807     if (occupied == 0) {
2808       tty->print_cr("  RSet is empty");
2809     } else {
2810       hrrs->print();
2811     }
2812     tty->print_cr("----------");
2813     return false;
2814   }
2815 
2816   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2817     tty->cr();
2818     tty->print_cr("========================================");
2819     tty->print_cr("%s", msg);
2820     tty->cr();
2821   }
2822 
2823   ~PrintRSetsClosure() {
2824     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2825     tty->print_cr("========================================");
2826     tty->cr();
2827   }
2828 };
2829 
2830 void G1CollectedHeap::print_cset_rsets() {
2831   PrintRSetsClosure cl("Printing CSet RSets");
2832   collection_set_iterate(&cl);
2833 }
2834 
2835 void G1CollectedHeap::print_all_rsets() {
2836   PrintRSetsClosure cl("Printing All RSets");;
2837   heap_region_iterate(&cl);
2838 }
2839 #endif // PRODUCT
2840 
2841 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2842   YoungList* young_list = heap()->young_list();
2843 
2844   size_t eden_used_bytes = young_list->eden_used_bytes();
2845   size_t survivor_used_bytes = young_list->survivor_used_bytes();
2846 
2847   size_t eden_capacity_bytes =
2848     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2849 
2850   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2851   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
2852 }
2853 
2854 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2855   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2856                        stats->unused(), stats->used(), stats->region_end_waste(),
2857                        stats->regions_filled(), stats->direct_allocated(),
2858                        stats->failure_used(), stats->failure_waste());
2859 }
2860 
2861 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2862   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2863   gc_tracer->report_gc_heap_summary(when, heap_summary);
2864 
2865   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2866   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2867 }
2868 
2869 
2870 G1CollectedHeap* G1CollectedHeap::heap() {
2871   CollectedHeap* heap = Universe::heap();
2872   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2873   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2874   return (G1CollectedHeap*)heap;
2875 }
2876 
2877 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2878   // always_do_update_barrier = false;
2879   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2880   // Fill TLAB's and such
2881   accumulate_statistics_all_tlabs();
2882   ensure_parsability(true);
2883 
2884   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2885 }
2886 
2887 void G1CollectedHeap::gc_epilogue(bool full) {
2888   // we are at the end of the GC. Total collections has already been increased.
2889   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2890 
2891   // FIXME: what is this about?
2892   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2893   // is set.
2894 #if defined(COMPILER2) || INCLUDE_JVMCI
2895   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2896 #endif
2897   // always_do_update_barrier = true;
2898 
2899   resize_all_tlabs();
2900   allocation_context_stats().update(full);
2901 
2902   // We have just completed a GC. Update the soft reference
2903   // policy with the new heap occupancy
2904   Universe::update_heap_info_at_gc();
2905 }
2906 
2907 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2908                                                uint gc_count_before,
2909                                                bool* succeeded,
2910                                                GCCause::Cause gc_cause) {
2911   assert_heap_not_locked_and_not_at_safepoint();
2912   g1_policy()->record_stop_world_start();
2913   VM_G1IncCollectionPause op(gc_count_before,
2914                              word_size,
2915                              false, /* should_initiate_conc_mark */
2916                              g1_policy()->max_pause_time_ms(),
2917                              gc_cause);
2918 
2919   op.set_allocation_context(AllocationContext::current());
2920   VMThread::execute(&op);
2921 
2922   HeapWord* result = op.result();
2923   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2924   assert(result == NULL || ret_succeeded,
2925          "the result should be NULL if the VM did not succeed");
2926   *succeeded = ret_succeeded;
2927 
2928   assert_heap_not_locked();
2929   return result;
2930 }
2931 
2932 void
2933 G1CollectedHeap::doConcurrentMark() {
2934   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2935   if (!_cmThread->in_progress()) {
2936     _cmThread->set_started();
2937     CGC_lock->notify();
2938   }
2939 }
2940 
2941 size_t G1CollectedHeap::pending_card_num() {
2942   size_t extra_cards = 0;
2943   JavaThread *curr = Threads::first();
2944   while (curr != NULL) {
2945     DirtyCardQueue& dcq = curr->dirty_card_queue();
2946     extra_cards += dcq.size();
2947     curr = curr->next();
2948   }
2949   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2950   size_t buffer_size = dcqs.buffer_size();
2951   size_t buffer_num = dcqs.completed_buffers_num();
2952 
2953   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2954   // in bytes - not the number of 'entries'. We need to convert
2955   // into a number of cards.
2956   return (buffer_size * buffer_num + extra_cards) / oopSize;
2957 }
2958 
2959 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2960  private:
2961   size_t _total_humongous;
2962   size_t _candidate_humongous;
2963 
2964   DirtyCardQueue _dcq;
2965 
2966   // We don't nominate objects with many remembered set entries, on
2967   // the assumption that such objects are likely still live.
2968   bool is_remset_small(HeapRegion* region) const {
2969     HeapRegionRemSet* const rset = region->rem_set();
2970     return G1EagerReclaimHumongousObjectsWithStaleRefs
2971       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2972       : rset->is_empty();
2973   }
2974 
2975   bool is_typeArray_region(HeapRegion* region) const {
2976     return oop(region->bottom())->is_typeArray();
2977   }
2978 
2979   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2980     assert(region->is_starts_humongous(), "Must start a humongous object");
2981 
2982     // Candidate selection must satisfy the following constraints
2983     // while concurrent marking is in progress:
2984     //
2985     // * In order to maintain SATB invariants, an object must not be
2986     // reclaimed if it was allocated before the start of marking and
2987     // has not had its references scanned.  Such an object must have
2988     // its references (including type metadata) scanned to ensure no
2989     // live objects are missed by the marking process.  Objects
2990     // allocated after the start of concurrent marking don't need to
2991     // be scanned.
2992     //
2993     // * An object must not be reclaimed if it is on the concurrent
2994     // mark stack.  Objects allocated after the start of concurrent
2995     // marking are never pushed on the mark stack.
2996     //
2997     // Nominating only objects allocated after the start of concurrent
2998     // marking is sufficient to meet both constraints.  This may miss
2999     // some objects that satisfy the constraints, but the marking data
3000     // structures don't support efficiently performing the needed
3001     // additional tests or scrubbing of the mark stack.
3002     //
3003     // However, we presently only nominate is_typeArray() objects.
3004     // A humongous object containing references induces remembered
3005     // set entries on other regions.  In order to reclaim such an
3006     // object, those remembered sets would need to be cleaned up.
3007     //
3008     // We also treat is_typeArray() objects specially, allowing them
3009     // to be reclaimed even if allocated before the start of
3010     // concurrent mark.  For this we rely on mark stack insertion to
3011     // exclude is_typeArray() objects, preventing reclaiming an object
3012     // that is in the mark stack.  We also rely on the metadata for
3013     // such objects to be built-in and so ensured to be kept live.
3014     // Frequent allocation and drop of large binary blobs is an
3015     // important use case for eager reclaim, and this special handling
3016     // may reduce needed headroom.
3017 
3018     return is_typeArray_region(region) && is_remset_small(region);
3019   }
3020 
3021  public:
3022   RegisterHumongousWithInCSetFastTestClosure()
3023   : _total_humongous(0),
3024     _candidate_humongous(0),
3025     _dcq(&JavaThread::dirty_card_queue_set()) {
3026   }
3027 
3028   virtual bool doHeapRegion(HeapRegion* r) {
3029     if (!r->is_starts_humongous()) {
3030       return false;
3031     }
3032     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3033 
3034     bool is_candidate = humongous_region_is_candidate(g1h, r);
3035     uint rindex = r->hrm_index();
3036     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3037     if (is_candidate) {
3038       _candidate_humongous++;
3039       g1h->register_humongous_region_with_cset(rindex);
3040       // Is_candidate already filters out humongous object with large remembered sets.
3041       // If we have a humongous object with a few remembered sets, we simply flush these
3042       // remembered set entries into the DCQS. That will result in automatic
3043       // re-evaluation of their remembered set entries during the following evacuation
3044       // phase.
3045       if (!r->rem_set()->is_empty()) {
3046         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3047                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3048         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3049         HeapRegionRemSetIterator hrrs(r->rem_set());
3050         size_t card_index;
3051         while (hrrs.has_next(card_index)) {
3052           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3053           // The remembered set might contain references to already freed
3054           // regions. Filter out such entries to avoid failing card table
3055           // verification.
3056           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3057             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3058               *card_ptr = CardTableModRefBS::dirty_card_val();
3059               _dcq.enqueue(card_ptr);
3060             }
3061           }
3062         }
3063         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3064                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3065                hrrs.n_yielded(), r->rem_set()->occupied());
3066         r->rem_set()->clear_locked();
3067       }
3068       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3069     }
3070     _total_humongous++;
3071 
3072     return false;
3073   }
3074 
3075   size_t total_humongous() const { return _total_humongous; }
3076   size_t candidate_humongous() const { return _candidate_humongous; }
3077 
3078   void flush_rem_set_entries() { _dcq.flush(); }
3079 };
3080 
3081 void G1CollectedHeap::register_humongous_regions_with_cset() {
3082   if (!G1EagerReclaimHumongousObjects) {
3083     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3084     return;
3085   }
3086   double time = os::elapsed_counter();
3087 
3088   // Collect reclaim candidate information and register candidates with cset.
3089   RegisterHumongousWithInCSetFastTestClosure cl;
3090   heap_region_iterate(&cl);
3091 
3092   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3093   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3094                                                                   cl.total_humongous(),
3095                                                                   cl.candidate_humongous());
3096   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3097 
3098   // Finally flush all remembered set entries to re-check into the global DCQS.
3099   cl.flush_rem_set_entries();
3100 }
3101 
3102 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3103   public:
3104     bool doHeapRegion(HeapRegion* hr) {
3105       if (!hr->is_archive() && !hr->is_continues_humongous()) {
3106         hr->verify_rem_set();
3107       }
3108       return false;
3109     }
3110 };
3111 
3112 #ifdef ASSERT
3113 class VerifyCSetClosure: public HeapRegionClosure {
3114 public:
3115   bool doHeapRegion(HeapRegion* hr) {
3116     // Here we check that the CSet region's RSet is ready for parallel
3117     // iteration. The fields that we'll verify are only manipulated
3118     // when the region is part of a CSet and is collected. Afterwards,
3119     // we reset these fields when we clear the region's RSet (when the
3120     // region is freed) so they are ready when the region is
3121     // re-allocated. The only exception to this is if there's an
3122     // evacuation failure and instead of freeing the region we leave
3123     // it in the heap. In that case, we reset these fields during
3124     // evacuation failure handling.
3125     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3126 
3127     // Here's a good place to add any other checks we'd like to
3128     // perform on CSet regions.
3129     return false;
3130   }
3131 };
3132 #endif // ASSERT
3133 
3134 uint G1CollectedHeap::num_task_queues() const {
3135   return _task_queues->size();
3136 }
3137 
3138 #if TASKQUEUE_STATS
3139 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3140   st->print_raw_cr("GC Task Stats");
3141   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3142   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3143 }
3144 
3145 void G1CollectedHeap::print_taskqueue_stats() const {
3146   if (!log_develop_is_enabled(Trace, gc, task, stats)) {
3147     return;
3148   }
3149   LogHandle(gc, task, stats) log;
3150   ResourceMark rm;
3151   outputStream* st = log.trace_stream();
3152 
3153   print_taskqueue_stats_hdr(st);
3154 
3155   TaskQueueStats totals;
3156   const uint n = num_task_queues();
3157   for (uint i = 0; i < n; ++i) {
3158     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3159     totals += task_queue(i)->stats;
3160   }
3161   st->print_raw("tot "); totals.print(st); st->cr();
3162 
3163   DEBUG_ONLY(totals.verify());
3164 }
3165 
3166 void G1CollectedHeap::reset_taskqueue_stats() {
3167   const uint n = num_task_queues();
3168   for (uint i = 0; i < n; ++i) {
3169     task_queue(i)->stats.reset();
3170   }
3171 }
3172 #endif // TASKQUEUE_STATS
3173 
3174 void G1CollectedHeap::wait_for_root_region_scanning() {
3175   double scan_wait_start = os::elapsedTime();
3176   // We have to wait until the CM threads finish scanning the
3177   // root regions as it's the only way to ensure that all the
3178   // objects on them have been correctly scanned before we start
3179   // moving them during the GC.
3180   bool waited = _cm->root_regions()->wait_until_scan_finished();
3181   double wait_time_ms = 0.0;
3182   if (waited) {
3183     double scan_wait_end = os::elapsedTime();
3184     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3185   }
3186   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3187 }
3188 
3189 bool
3190 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3191   assert_at_safepoint(true /* should_be_vm_thread */);
3192   guarantee(!is_gc_active(), "collection is not reentrant");
3193 
3194   if (GCLocker::check_active_before_gc()) {
3195     return false;
3196   }
3197 
3198   _gc_timer_stw->register_gc_start();
3199 
3200   GCIdMark gc_id_mark;
3201   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3202 
3203   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3204   ResourceMark rm;
3205 
3206   wait_for_root_region_scanning();
3207 
3208   print_heap_before_gc();
3209   trace_heap_before_gc(_gc_tracer_stw);
3210 
3211   _verifier->verify_region_sets_optional();
3212   _verifier->verify_dirty_young_regions();
3213 
3214   // This call will decide whether this pause is an initial-mark
3215   // pause. If it is, during_initial_mark_pause() will return true
3216   // for the duration of this pause.
3217   g1_policy()->decide_on_conc_mark_initiation();
3218 
3219   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3220   assert(!collector_state()->during_initial_mark_pause() ||
3221           collector_state()->gcs_are_young(), "sanity");
3222 
3223   // We also do not allow mixed GCs during marking.
3224   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3225 
3226   // Record whether this pause is an initial mark. When the current
3227   // thread has completed its logging output and it's safe to signal
3228   // the CM thread, the flag's value in the policy has been reset.
3229   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3230 
3231   // Inner scope for scope based logging, timers, and stats collection
3232   {
3233     EvacuationInfo evacuation_info;
3234 
3235     if (collector_state()->during_initial_mark_pause()) {
3236       // We are about to start a marking cycle, so we increment the
3237       // full collection counter.
3238       increment_old_marking_cycles_started();
3239       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3240     }
3241 
3242     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3243 
3244     GCTraceCPUTime tcpu;
3245 
3246     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3247                                                                   workers()->active_workers(),
3248                                                                   Threads::number_of_non_daemon_threads());
3249     workers()->set_active_workers(active_workers);
3250     FormatBuffer<> gc_string("Pause ");
3251     if (collector_state()->during_initial_mark_pause()) {
3252       gc_string.append("Initial Mark");
3253     } else if (collector_state()->gcs_are_young()) {
3254       gc_string.append("Young");
3255     } else {
3256       gc_string.append("Mixed");
3257     }
3258     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3259 
3260     g1_policy()->note_gc_start(active_workers);
3261 
3262     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3263     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3264 
3265     // If the secondary_free_list is not empty, append it to the
3266     // free_list. No need to wait for the cleanup operation to finish;
3267     // the region allocation code will check the secondary_free_list
3268     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3269     // set, skip this step so that the region allocation code has to
3270     // get entries from the secondary_free_list.
3271     if (!G1StressConcRegionFreeing) {
3272       append_secondary_free_list_if_not_empty_with_lock();
3273     }
3274 
3275     G1HeapTransition heap_transition(this);
3276     size_t heap_used_bytes_before_gc = used();
3277 
3278     assert(check_young_list_well_formed(), "young list should be well formed");
3279 
3280     // Don't dynamically change the number of GC threads this early.  A value of
3281     // 0 is used to indicate serial work.  When parallel work is done,
3282     // it will be set.
3283 
3284     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3285       IsGCActiveMark x;
3286 
3287       gc_prologue(false);
3288       increment_total_collections(false /* full gc */);
3289       increment_gc_time_stamp();
3290 
3291       if (VerifyRememberedSets) {
3292         log_info(gc, verify)("[Verifying RemSets before GC]");
3293         VerifyRegionRemSetClosure v_cl;
3294         heap_region_iterate(&v_cl);
3295       }
3296 
3297       _verifier->verify_before_gc();
3298 
3299       _verifier->check_bitmaps("GC Start");
3300 
3301 #if defined(COMPILER2) || INCLUDE_JVMCI
3302       DerivedPointerTable::clear();
3303 #endif
3304 
3305       // Please see comment in g1CollectedHeap.hpp and
3306       // G1CollectedHeap::ref_processing_init() to see how
3307       // reference processing currently works in G1.
3308 
3309       // Enable discovery in the STW reference processor
3310       if (g1_policy()->should_process_references()) {
3311         ref_processor_stw()->enable_discovery();
3312       } else {
3313         ref_processor_stw()->disable_discovery();
3314       }
3315 
3316       {
3317         // We want to temporarily turn off discovery by the
3318         // CM ref processor, if necessary, and turn it back on
3319         // on again later if we do. Using a scoped
3320         // NoRefDiscovery object will do this.
3321         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3322 
3323         // Forget the current alloc region (we might even choose it to be part
3324         // of the collection set!).
3325         _allocator->release_mutator_alloc_region();
3326 
3327         // This timing is only used by the ergonomics to handle our pause target.
3328         // It is unclear why this should not include the full pause. We will
3329         // investigate this in CR 7178365.
3330         //
3331         // Preserving the old comment here if that helps the investigation:
3332         //
3333         // The elapsed time induced by the start time below deliberately elides
3334         // the possible verification above.
3335         double sample_start_time_sec = os::elapsedTime();
3336 
3337         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3338 
3339         if (collector_state()->during_initial_mark_pause()) {
3340           concurrent_mark()->checkpointRootsInitialPre();
3341         }
3342 
3343         double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3344         g1_policy()->finalize_old_cset_part(time_remaining_ms);
3345 
3346         evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3347 
3348         // Make sure the remembered sets are up to date. This needs to be
3349         // done before register_humongous_regions_with_cset(), because the
3350         // remembered sets are used there to choose eager reclaim candidates.
3351         // If the remembered sets are not up to date we might miss some
3352         // entries that need to be handled.
3353         g1_rem_set()->cleanupHRRS();
3354 
3355         register_humongous_regions_with_cset();
3356 
3357         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3358 
3359         _cm->note_start_of_gc();
3360         // We call this after finalize_cset() to
3361         // ensure that the CSet has been finalized.
3362         _cm->verify_no_cset_oops();
3363 
3364         if (_hr_printer.is_active()) {
3365           HeapRegion* hr = g1_policy()->collection_set();
3366           while (hr != NULL) {
3367             _hr_printer.cset(hr);
3368             hr = hr->next_in_collection_set();
3369           }
3370         }
3371 
3372 #ifdef ASSERT
3373         VerifyCSetClosure cl;
3374         collection_set_iterate(&cl);
3375 #endif // ASSERT
3376 
3377         // Initialize the GC alloc regions.
3378         _allocator->init_gc_alloc_regions(evacuation_info);
3379 
3380         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3381         pre_evacuate_collection_set();
3382 
3383         // Actually do the work...
3384         evacuate_collection_set(evacuation_info, &per_thread_states);
3385 
3386         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3387 
3388         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3389         free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3390 
3391         eagerly_reclaim_humongous_regions();
3392 
3393         g1_policy()->clear_collection_set();
3394 
3395         // Start a new incremental collection set for the next pause.
3396         g1_policy()->start_incremental_cset_building();
3397 
3398         clear_cset_fast_test();
3399 
3400         _young_list->reset_sampled_info();
3401 
3402         // Don't check the whole heap at this point as the
3403         // GC alloc regions from this pause have been tagged
3404         // as survivors and moved on to the survivor list.
3405         // Survivor regions will fail the !is_young() check.
3406         assert(check_young_list_empty(false /* check_heap */),
3407           "young list should be empty");
3408 
3409         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3410                                              _young_list->first_survivor_region(),
3411                                              _young_list->last_survivor_region());
3412 
3413         _young_list->reset_auxilary_lists();
3414 
3415         if (evacuation_failed()) {
3416           set_used(recalculate_used());
3417           if (_archive_allocator != NULL) {
3418             _archive_allocator->clear_used();
3419           }
3420           for (uint i = 0; i < ParallelGCThreads; i++) {
3421             if (_evacuation_failed_info_array[i].has_failed()) {
3422               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3423             }
3424           }
3425         } else {
3426           // The "used" of the the collection set have already been subtracted
3427           // when they were freed.  Add in the bytes evacuated.
3428           increase_used(g1_policy()->bytes_copied_during_gc());
3429         }
3430 
3431         if (collector_state()->during_initial_mark_pause()) {
3432           // We have to do this before we notify the CM threads that
3433           // they can start working to make sure that all the
3434           // appropriate initialization is done on the CM object.
3435           concurrent_mark()->checkpointRootsInitialPost();
3436           collector_state()->set_mark_in_progress(true);
3437           // Note that we don't actually trigger the CM thread at
3438           // this point. We do that later when we're sure that
3439           // the current thread has completed its logging output.
3440         }
3441 
3442         allocate_dummy_regions();
3443 
3444         _allocator->init_mutator_alloc_region();
3445 
3446         {
3447           size_t expand_bytes = g1_policy()->expansion_amount();
3448           if (expand_bytes > 0) {
3449             size_t bytes_before = capacity();
3450             // No need for an ergo logging here,
3451             // expansion_amount() does this when it returns a value > 0.
3452             double expand_ms;
3453             if (!expand(expand_bytes, &expand_ms)) {
3454               // We failed to expand the heap. Cannot do anything about it.
3455             }
3456             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3457           }
3458         }
3459 
3460         // We redo the verification but now wrt to the new CSet which
3461         // has just got initialized after the previous CSet was freed.
3462         _cm->verify_no_cset_oops();
3463         _cm->note_end_of_gc();
3464 
3465         // This timing is only used by the ergonomics to handle our pause target.
3466         // It is unclear why this should not include the full pause. We will
3467         // investigate this in CR 7178365.
3468         double sample_end_time_sec = os::elapsedTime();
3469         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3470         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3471         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3472 
3473         evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3474         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3475 
3476         MemoryService::track_memory_usage();
3477 
3478         // In prepare_for_verify() below we'll need to scan the deferred
3479         // update buffers to bring the RSets up-to-date if
3480         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3481         // the update buffers we'll probably need to scan cards on the
3482         // regions we just allocated to (i.e., the GC alloc
3483         // regions). However, during the last GC we called
3484         // set_saved_mark() on all the GC alloc regions, so card
3485         // scanning might skip the [saved_mark_word()...top()] area of
3486         // those regions (i.e., the area we allocated objects into
3487         // during the last GC). But it shouldn't. Given that
3488         // saved_mark_word() is conditional on whether the GC time stamp
3489         // on the region is current or not, by incrementing the GC time
3490         // stamp here we invalidate all the GC time stamps on all the
3491         // regions and saved_mark_word() will simply return top() for
3492         // all the regions. This is a nicer way of ensuring this rather
3493         // than iterating over the regions and fixing them. In fact, the
3494         // GC time stamp increment here also ensures that
3495         // saved_mark_word() will return top() between pauses, i.e.,
3496         // during concurrent refinement. So we don't need the
3497         // is_gc_active() check to decided which top to use when
3498         // scanning cards (see CR 7039627).
3499         increment_gc_time_stamp();
3500 
3501         if (VerifyRememberedSets) {
3502           log_info(gc, verify)("[Verifying RemSets after GC]");
3503           VerifyRegionRemSetClosure v_cl;
3504           heap_region_iterate(&v_cl);
3505         }
3506 
3507         _verifier->verify_after_gc();
3508         _verifier->check_bitmaps("GC End");
3509 
3510         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3511         ref_processor_stw()->verify_no_references_recorded();
3512 
3513         // CM reference discovery will be re-enabled if necessary.
3514       }
3515 
3516 #ifdef TRACESPINNING
3517       ParallelTaskTerminator::print_termination_counts();
3518 #endif
3519 
3520       gc_epilogue(false);
3521     }
3522 
3523     // Print the remainder of the GC log output.
3524     if (evacuation_failed()) {
3525       log_info(gc)("To-space exhausted");
3526     }
3527 
3528     g1_policy()->print_phases();
3529     heap_transition.print();
3530 
3531     // It is not yet to safe to tell the concurrent mark to
3532     // start as we have some optional output below. We don't want the
3533     // output from the concurrent mark thread interfering with this
3534     // logging output either.
3535 
3536     _hrm.verify_optional();
3537     _verifier->verify_region_sets_optional();
3538 
3539     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3540     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3541 
3542     print_heap_after_gc();
3543     trace_heap_after_gc(_gc_tracer_stw);
3544 
3545     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3546     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3547     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3548     // before any GC notifications are raised.
3549     g1mm()->update_sizes();
3550 
3551     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3552     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3553     _gc_timer_stw->register_gc_end();
3554     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3555   }
3556   // It should now be safe to tell the concurrent mark thread to start
3557   // without its logging output interfering with the logging output
3558   // that came from the pause.
3559 
3560   if (should_start_conc_mark) {
3561     // CAUTION: after the doConcurrentMark() call below,
3562     // the concurrent marking thread(s) could be running
3563     // concurrently with us. Make sure that anything after
3564     // this point does not assume that we are the only GC thread
3565     // running. Note: of course, the actual marking work will
3566     // not start until the safepoint itself is released in
3567     // SuspendibleThreadSet::desynchronize().
3568     doConcurrentMark();
3569   }
3570 
3571   return true;
3572 }
3573 
3574 void G1CollectedHeap::restore_preserved_marks() {
3575   G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3576   workers()->run_task(&rpm_task);
3577 }
3578 
3579 void G1CollectedHeap::remove_self_forwarding_pointers() {
3580   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3581   workers()->run_task(&rsfp_task);
3582 }
3583 
3584 void G1CollectedHeap::restore_after_evac_failure() {
3585   double remove_self_forwards_start = os::elapsedTime();
3586 
3587   remove_self_forwarding_pointers();
3588   restore_preserved_marks();
3589 
3590   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3591 }
3592 
3593 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3594   if (!_evacuation_failed) {
3595     _evacuation_failed = true;
3596   }
3597 
3598   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3599 
3600   // We want to call the "for_promotion_failure" version only in the
3601   // case of a promotion failure.
3602   if (m->must_be_preserved_for_promotion_failure(obj)) {
3603     OopAndMarkOop elem(obj, m);
3604     _preserved_objs[worker_id].push(elem);
3605   }
3606 }
3607 
3608 bool G1ParEvacuateFollowersClosure::offer_termination() {
3609   G1ParScanThreadState* const pss = par_scan_state();
3610   start_term_time();
3611   const bool res = terminator()->offer_termination();
3612   end_term_time();
3613   return res;
3614 }
3615 
3616 void G1ParEvacuateFollowersClosure::do_void() {
3617   G1ParScanThreadState* const pss = par_scan_state();
3618   pss->trim_queue();
3619   do {
3620     pss->steal_and_trim_queue(queues());
3621   } while (!offer_termination());
3622 }
3623 
3624 class G1ParTask : public AbstractGangTask {
3625 protected:
3626   G1CollectedHeap*         _g1h;
3627   G1ParScanThreadStateSet* _pss;
3628   RefToScanQueueSet*       _queues;
3629   G1RootProcessor*         _root_processor;
3630   ParallelTaskTerminator   _terminator;
3631   uint                     _n_workers;
3632 
3633 public:
3634   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3635     : AbstractGangTask("G1 collection"),
3636       _g1h(g1h),
3637       _pss(per_thread_states),
3638       _queues(task_queues),
3639       _root_processor(root_processor),
3640       _terminator(n_workers, _queues),
3641       _n_workers(n_workers)
3642   {}
3643 
3644   void work(uint worker_id) {
3645     if (worker_id >= _n_workers) return;  // no work needed this round
3646 
3647     double start_sec = os::elapsedTime();
3648     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3649 
3650     {
3651       ResourceMark rm;
3652       HandleMark   hm;
3653 
3654       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3655 
3656       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3657       pss->set_ref_processor(rp);
3658 
3659       double start_strong_roots_sec = os::elapsedTime();
3660 
3661       _root_processor->evacuate_roots(pss->closures(), worker_id);
3662 
3663       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3664 
3665       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3666       // treating the nmethods visited to act as roots for concurrent marking.
3667       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3668       // objects copied by the current evacuation.
3669       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3670                                                                              pss->closures()->weak_codeblobs(),
3671                                                                              worker_id);
3672 
3673       _pss->add_cards_scanned(worker_id, cards_scanned);
3674 
3675       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3676 
3677       double term_sec = 0.0;
3678       size_t evac_term_attempts = 0;
3679       {
3680         double start = os::elapsedTime();
3681         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3682         evac.do_void();
3683 
3684         evac_term_attempts = evac.term_attempts();
3685         term_sec = evac.term_time();
3686         double elapsed_sec = os::elapsedTime() - start;
3687         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3688         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3689         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3690       }
3691 
3692       assert(pss->queue_is_empty(), "should be empty");
3693 
3694       if (log_is_enabled(Debug, gc, task, stats)) {
3695         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3696         size_t lab_waste;
3697         size_t lab_undo_waste;
3698         pss->waste(lab_waste, lab_undo_waste);
3699         _g1h->print_termination_stats(worker_id,
3700                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3701                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3702                                       term_sec * 1000.0,                          /* evac term time */
3703                                       evac_term_attempts,                         /* evac term attempts */
3704                                       lab_waste,                                  /* alloc buffer waste */
3705                                       lab_undo_waste                              /* undo waste */
3706                                       );
3707       }
3708 
3709       // Close the inner scope so that the ResourceMark and HandleMark
3710       // destructors are executed here and are included as part of the
3711       // "GC Worker Time".
3712     }
3713     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3714   }
3715 };
3716 
3717 void G1CollectedHeap::print_termination_stats_hdr() {
3718   log_debug(gc, task, stats)("GC Termination Stats");
3719   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3720   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3721   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3722 }
3723 
3724 void G1CollectedHeap::print_termination_stats(uint worker_id,
3725                                               double elapsed_ms,
3726                                               double strong_roots_ms,
3727                                               double term_ms,
3728                                               size_t term_attempts,
3729                                               size_t alloc_buffer_waste,
3730                                               size_t undo_waste) const {
3731   log_debug(gc, task, stats)
3732               ("%3d %9.2f %9.2f %6.2f "
3733                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3734                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3735                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3736                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3737                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3738                alloc_buffer_waste * HeapWordSize / K,
3739                undo_waste * HeapWordSize / K);
3740 }
3741 
3742 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3743 private:
3744   BoolObjectClosure* _is_alive;
3745   int _initial_string_table_size;
3746   int _initial_symbol_table_size;
3747 
3748   bool  _process_strings;
3749   int _strings_processed;
3750   int _strings_removed;
3751 
3752   bool  _process_symbols;
3753   int _symbols_processed;
3754   int _symbols_removed;
3755 
3756 public:
3757   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3758     AbstractGangTask("String/Symbol Unlinking"),
3759     _is_alive(is_alive),
3760     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3761     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3762 
3763     _initial_string_table_size = StringTable::the_table()->table_size();
3764     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3765     if (process_strings) {
3766       StringTable::clear_parallel_claimed_index();
3767     }
3768     if (process_symbols) {
3769       SymbolTable::clear_parallel_claimed_index();
3770     }
3771   }
3772 
3773   ~G1StringSymbolTableUnlinkTask() {
3774     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3775               "claim value %d after unlink less than initial string table size %d",
3776               StringTable::parallel_claimed_index(), _initial_string_table_size);
3777     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3778               "claim value %d after unlink less than initial symbol table size %d",
3779               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3780 
3781     log_debug(gc, stringdedup)("Cleaned string and symbol table, "
3782                                "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3783                                "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3784                                strings_processed(), strings_removed(),
3785                                symbols_processed(), symbols_removed());
3786   }
3787 
3788   void work(uint worker_id) {
3789     int strings_processed = 0;
3790     int strings_removed = 0;
3791     int symbols_processed = 0;
3792     int symbols_removed = 0;
3793     if (_process_strings) {
3794       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3795       Atomic::add(strings_processed, &_strings_processed);
3796       Atomic::add(strings_removed, &_strings_removed);
3797     }
3798     if (_process_symbols) {
3799       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3800       Atomic::add(symbols_processed, &_symbols_processed);
3801       Atomic::add(symbols_removed, &_symbols_removed);
3802     }
3803   }
3804 
3805   size_t strings_processed() const { return (size_t)_strings_processed; }
3806   size_t strings_removed()   const { return (size_t)_strings_removed; }
3807 
3808   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3809   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3810 };
3811 
3812 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3813 private:
3814   static Monitor* _lock;
3815 
3816   BoolObjectClosure* const _is_alive;
3817   const bool               _unloading_occurred;
3818   const uint               _num_workers;
3819 
3820   // Variables used to claim nmethods.
3821   nmethod* _first_nmethod;
3822   volatile nmethod* _claimed_nmethod;
3823 
3824   // The list of nmethods that need to be processed by the second pass.
3825   volatile nmethod* _postponed_list;
3826   volatile uint     _num_entered_barrier;
3827 
3828  public:
3829   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3830       _is_alive(is_alive),
3831       _unloading_occurred(unloading_occurred),
3832       _num_workers(num_workers),
3833       _first_nmethod(NULL),
3834       _claimed_nmethod(NULL),
3835       _postponed_list(NULL),
3836       _num_entered_barrier(0)
3837   {
3838     nmethod::increase_unloading_clock();
3839     // Get first alive nmethod
3840     NMethodIterator iter = NMethodIterator();
3841     if(iter.next_alive()) {
3842       _first_nmethod = iter.method();
3843     }
3844     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3845   }
3846 
3847   ~G1CodeCacheUnloadingTask() {
3848     CodeCache::verify_clean_inline_caches();
3849 
3850     CodeCache::set_needs_cache_clean(false);
3851     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3852 
3853     CodeCache::verify_icholder_relocations();
3854   }
3855 
3856  private:
3857   void add_to_postponed_list(nmethod* nm) {
3858       nmethod* old;
3859       do {
3860         old = (nmethod*)_postponed_list;
3861         nm->set_unloading_next(old);
3862       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3863   }
3864 
3865   void clean_nmethod(nmethod* nm) {
3866     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3867 
3868     if (postponed) {
3869       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3870       add_to_postponed_list(nm);
3871     }
3872 
3873     // Mark that this thread has been cleaned/unloaded.
3874     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3875     nm->set_unloading_clock(nmethod::global_unloading_clock());
3876   }
3877 
3878   void clean_nmethod_postponed(nmethod* nm) {
3879     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3880   }
3881 
3882   static const int MaxClaimNmethods = 16;
3883 
3884   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3885     nmethod* first;
3886     NMethodIterator last;
3887 
3888     do {
3889       *num_claimed_nmethods = 0;
3890 
3891       first = (nmethod*)_claimed_nmethod;
3892       last = NMethodIterator(first);
3893 
3894       if (first != NULL) {
3895 
3896         for (int i = 0; i < MaxClaimNmethods; i++) {
3897           if (!last.next_alive()) {
3898             break;
3899           }
3900           claimed_nmethods[i] = last.method();
3901           (*num_claimed_nmethods)++;
3902         }
3903       }
3904 
3905     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3906   }
3907 
3908   nmethod* claim_postponed_nmethod() {
3909     nmethod* claim;
3910     nmethod* next;
3911 
3912     do {
3913       claim = (nmethod*)_postponed_list;
3914       if (claim == NULL) {
3915         return NULL;
3916       }
3917 
3918       next = claim->unloading_next();
3919 
3920     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3921 
3922     return claim;
3923   }
3924 
3925  public:
3926   // Mark that we're done with the first pass of nmethod cleaning.
3927   void barrier_mark(uint worker_id) {
3928     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3929     _num_entered_barrier++;
3930     if (_num_entered_barrier == _num_workers) {
3931       ml.notify_all();
3932     }
3933   }
3934 
3935   // See if we have to wait for the other workers to
3936   // finish their first-pass nmethod cleaning work.
3937   void barrier_wait(uint worker_id) {
3938     if (_num_entered_barrier < _num_workers) {
3939       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3940       while (_num_entered_barrier < _num_workers) {
3941           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3942       }
3943     }
3944   }
3945 
3946   // Cleaning and unloading of nmethods. Some work has to be postponed
3947   // to the second pass, when we know which nmethods survive.
3948   void work_first_pass(uint worker_id) {
3949     // The first nmethods is claimed by the first worker.
3950     if (worker_id == 0 && _first_nmethod != NULL) {
3951       clean_nmethod(_first_nmethod);
3952       _first_nmethod = NULL;
3953     }
3954 
3955     int num_claimed_nmethods;
3956     nmethod* claimed_nmethods[MaxClaimNmethods];
3957 
3958     while (true) {
3959       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3960 
3961       if (num_claimed_nmethods == 0) {
3962         break;
3963       }
3964 
3965       for (int i = 0; i < num_claimed_nmethods; i++) {
3966         clean_nmethod(claimed_nmethods[i]);
3967       }
3968     }
3969   }
3970 
3971   void work_second_pass(uint worker_id) {
3972     nmethod* nm;
3973     // Take care of postponed nmethods.
3974     while ((nm = claim_postponed_nmethod()) != NULL) {
3975       clean_nmethod_postponed(nm);
3976     }
3977   }
3978 };
3979 
3980 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3981 
3982 class G1KlassCleaningTask : public StackObj {
3983   BoolObjectClosure*                      _is_alive;
3984   volatile jint                           _clean_klass_tree_claimed;
3985   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3986 
3987  public:
3988   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3989       _is_alive(is_alive),
3990       _clean_klass_tree_claimed(0),
3991       _klass_iterator() {
3992   }
3993 
3994  private:
3995   bool claim_clean_klass_tree_task() {
3996     if (_clean_klass_tree_claimed) {
3997       return false;
3998     }
3999 
4000     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4001   }
4002 
4003   InstanceKlass* claim_next_klass() {
4004     Klass* klass;
4005     do {
4006       klass =_klass_iterator.next_klass();
4007     } while (klass != NULL && !klass->is_instance_klass());
4008 
4009     // this can be null so don't call InstanceKlass::cast
4010     return static_cast<InstanceKlass*>(klass);
4011   }
4012 
4013 public:
4014 
4015   void clean_klass(InstanceKlass* ik) {
4016     ik->clean_weak_instanceklass_links(_is_alive);
4017   }
4018 
4019   void work() {
4020     ResourceMark rm;
4021 
4022     // One worker will clean the subklass/sibling klass tree.
4023     if (claim_clean_klass_tree_task()) {
4024       Klass::clean_subklass_tree(_is_alive);
4025     }
4026 
4027     // All workers will help cleaning the classes,
4028     InstanceKlass* klass;
4029     while ((klass = claim_next_klass()) != NULL) {
4030       clean_klass(klass);
4031     }
4032   }
4033 };
4034 
4035 // To minimize the remark pause times, the tasks below are done in parallel.
4036 class G1ParallelCleaningTask : public AbstractGangTask {
4037 private:
4038   G1StringSymbolTableUnlinkTask _string_symbol_task;
4039   G1CodeCacheUnloadingTask      _code_cache_task;
4040   G1KlassCleaningTask           _klass_cleaning_task;
4041 
4042 public:
4043   // The constructor is run in the VMThread.
4044   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4045       AbstractGangTask("Parallel Cleaning"),
4046       _string_symbol_task(is_alive, process_strings, process_symbols),
4047       _code_cache_task(num_workers, is_alive, unloading_occurred),
4048       _klass_cleaning_task(is_alive) {
4049   }
4050 
4051   // The parallel work done by all worker threads.
4052   void work(uint worker_id) {
4053     // Do first pass of code cache cleaning.
4054     _code_cache_task.work_first_pass(worker_id);
4055 
4056     // Let the threads mark that the first pass is done.
4057     _code_cache_task.barrier_mark(worker_id);
4058 
4059     // Clean the Strings and Symbols.
4060     _string_symbol_task.work(worker_id);
4061 
4062     // Wait for all workers to finish the first code cache cleaning pass.
4063     _code_cache_task.barrier_wait(worker_id);
4064 
4065     // Do the second code cache cleaning work, which realize on
4066     // the liveness information gathered during the first pass.
4067     _code_cache_task.work_second_pass(worker_id);
4068 
4069     // Clean all klasses that were not unloaded.
4070     _klass_cleaning_task.work();
4071   }
4072 };
4073 
4074 
4075 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4076                                         bool process_strings,
4077                                         bool process_symbols,
4078                                         bool class_unloading_occurred) {
4079   uint n_workers = workers()->active_workers();
4080 
4081   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4082                                         n_workers, class_unloading_occurred);
4083   workers()->run_task(&g1_unlink_task);
4084 }
4085 
4086 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4087                                                      bool process_strings, bool process_symbols) {
4088   {
4089     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4090     workers()->run_task(&g1_unlink_task);
4091   }
4092 
4093   if (G1StringDedup::is_enabled()) {
4094     G1StringDedup::unlink(is_alive);
4095   }
4096 }
4097 
4098 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4099  private:
4100   DirtyCardQueueSet* _queue;
4101   G1CollectedHeap* _g1h;
4102  public:
4103   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4104     _queue(queue), _g1h(g1h) { }
4105 
4106   virtual void work(uint worker_id) {
4107     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4108     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4109 
4110     RedirtyLoggedCardTableEntryClosure cl(_g1h);
4111     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4112 
4113     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4114   }
4115 };
4116 
4117 void G1CollectedHeap::redirty_logged_cards() {
4118   double redirty_logged_cards_start = os::elapsedTime();
4119 
4120   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4121   dirty_card_queue_set().reset_for_par_iteration();
4122   workers()->run_task(&redirty_task);
4123 
4124   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4125   dcq.merge_bufferlists(&dirty_card_queue_set());
4126   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4127 
4128   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4129 }
4130 
4131 // Weak Reference Processing support
4132 
4133 // An always "is_alive" closure that is used to preserve referents.
4134 // If the object is non-null then it's alive.  Used in the preservation
4135 // of referent objects that are pointed to by reference objects
4136 // discovered by the CM ref processor.
4137 class G1AlwaysAliveClosure: public BoolObjectClosure {
4138   G1CollectedHeap* _g1;
4139 public:
4140   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4141   bool do_object_b(oop p) {
4142     if (p != NULL) {
4143       return true;
4144     }
4145     return false;
4146   }
4147 };
4148 
4149 bool G1STWIsAliveClosure::do_object_b(oop p) {
4150   // An object is reachable if it is outside the collection set,
4151   // or is inside and copied.
4152   return !_g1->is_in_cset(p) || p->is_forwarded();
4153 }
4154 
4155 // Non Copying Keep Alive closure
4156 class G1KeepAliveClosure: public OopClosure {
4157   G1CollectedHeap* _g1;
4158 public:
4159   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4160   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4161   void do_oop(oop* p) {
4162     oop obj = *p;
4163     assert(obj != NULL, "the caller should have filtered out NULL values");
4164 
4165     const InCSetState cset_state = _g1->in_cset_state(obj);
4166     if (!cset_state.is_in_cset_or_humongous()) {
4167       return;
4168     }
4169     if (cset_state.is_in_cset()) {
4170       assert( obj->is_forwarded(), "invariant" );
4171       *p = obj->forwardee();
4172     } else {
4173       assert(!obj->is_forwarded(), "invariant" );
4174       assert(cset_state.is_humongous(),
4175              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4176       _g1->set_humongous_is_live(obj);
4177     }
4178   }
4179 };
4180 
4181 // Copying Keep Alive closure - can be called from both
4182 // serial and parallel code as long as different worker
4183 // threads utilize different G1ParScanThreadState instances
4184 // and different queues.
4185 
4186 class G1CopyingKeepAliveClosure: public OopClosure {
4187   G1CollectedHeap*         _g1h;
4188   OopClosure*              _copy_non_heap_obj_cl;
4189   G1ParScanThreadState*    _par_scan_state;
4190 
4191 public:
4192   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4193                             OopClosure* non_heap_obj_cl,
4194                             G1ParScanThreadState* pss):
4195     _g1h(g1h),
4196     _copy_non_heap_obj_cl(non_heap_obj_cl),
4197     _par_scan_state(pss)
4198   {}
4199 
4200   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4201   virtual void do_oop(      oop* p) { do_oop_work(p); }
4202 
4203   template <class T> void do_oop_work(T* p) {
4204     oop obj = oopDesc::load_decode_heap_oop(p);
4205 
4206     if (_g1h->is_in_cset_or_humongous(obj)) {
4207       // If the referent object has been forwarded (either copied
4208       // to a new location or to itself in the event of an
4209       // evacuation failure) then we need to update the reference
4210       // field and, if both reference and referent are in the G1
4211       // heap, update the RSet for the referent.
4212       //
4213       // If the referent has not been forwarded then we have to keep
4214       // it alive by policy. Therefore we have copy the referent.
4215       //
4216       // If the reference field is in the G1 heap then we can push
4217       // on the PSS queue. When the queue is drained (after each
4218       // phase of reference processing) the object and it's followers
4219       // will be copied, the reference field set to point to the
4220       // new location, and the RSet updated. Otherwise we need to
4221       // use the the non-heap or metadata closures directly to copy
4222       // the referent object and update the pointer, while avoiding
4223       // updating the RSet.
4224 
4225       if (_g1h->is_in_g1_reserved(p)) {
4226         _par_scan_state->push_on_queue(p);
4227       } else {
4228         assert(!Metaspace::contains((const void*)p),
4229                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4230         _copy_non_heap_obj_cl->do_oop(p);
4231       }
4232     }
4233   }
4234 };
4235 
4236 // Serial drain queue closure. Called as the 'complete_gc'
4237 // closure for each discovered list in some of the
4238 // reference processing phases.
4239 
4240 class G1STWDrainQueueClosure: public VoidClosure {
4241 protected:
4242   G1CollectedHeap* _g1h;
4243   G1ParScanThreadState* _par_scan_state;
4244 
4245   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4246 
4247 public:
4248   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4249     _g1h(g1h),
4250     _par_scan_state(pss)
4251   { }
4252 
4253   void do_void() {
4254     G1ParScanThreadState* const pss = par_scan_state();
4255     pss->trim_queue();
4256   }
4257 };
4258 
4259 // Parallel Reference Processing closures
4260 
4261 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4262 // processing during G1 evacuation pauses.
4263 
4264 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4265 private:
4266   G1CollectedHeap*          _g1h;
4267   G1ParScanThreadStateSet*  _pss;
4268   RefToScanQueueSet*        _queues;
4269   WorkGang*                 _workers;
4270   uint                      _active_workers;
4271 
4272 public:
4273   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4274                            G1ParScanThreadStateSet* per_thread_states,
4275                            WorkGang* workers,
4276                            RefToScanQueueSet *task_queues,
4277                            uint n_workers) :
4278     _g1h(g1h),
4279     _pss(per_thread_states),
4280     _queues(task_queues),
4281     _workers(workers),
4282     _active_workers(n_workers)
4283   {
4284     assert(n_workers > 0, "shouldn't call this otherwise");
4285   }
4286 
4287   // Executes the given task using concurrent marking worker threads.
4288   virtual void execute(ProcessTask& task);
4289   virtual void execute(EnqueueTask& task);
4290 };
4291 
4292 // Gang task for possibly parallel reference processing
4293 
4294 class G1STWRefProcTaskProxy: public AbstractGangTask {
4295   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4296   ProcessTask&     _proc_task;
4297   G1CollectedHeap* _g1h;
4298   G1ParScanThreadStateSet* _pss;
4299   RefToScanQueueSet* _task_queues;
4300   ParallelTaskTerminator* _terminator;
4301 
4302 public:
4303   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4304                         G1CollectedHeap* g1h,
4305                         G1ParScanThreadStateSet* per_thread_states,
4306                         RefToScanQueueSet *task_queues,
4307                         ParallelTaskTerminator* terminator) :
4308     AbstractGangTask("Process reference objects in parallel"),
4309     _proc_task(proc_task),
4310     _g1h(g1h),
4311     _pss(per_thread_states),
4312     _task_queues(task_queues),
4313     _terminator(terminator)
4314   {}
4315 
4316   virtual void work(uint worker_id) {
4317     // The reference processing task executed by a single worker.
4318     ResourceMark rm;
4319     HandleMark   hm;
4320 
4321     G1STWIsAliveClosure is_alive(_g1h);
4322 
4323     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4324     pss->set_ref_processor(NULL);
4325 
4326     // Keep alive closure.
4327     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4328 
4329     // Complete GC closure
4330     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4331 
4332     // Call the reference processing task's work routine.
4333     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4334 
4335     // Note we cannot assert that the refs array is empty here as not all
4336     // of the processing tasks (specifically phase2 - pp2_work) execute
4337     // the complete_gc closure (which ordinarily would drain the queue) so
4338     // the queue may not be empty.
4339   }
4340 };
4341 
4342 // Driver routine for parallel reference processing.
4343 // Creates an instance of the ref processing gang
4344 // task and has the worker threads execute it.
4345 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4346   assert(_workers != NULL, "Need parallel worker threads.");
4347 
4348   ParallelTaskTerminator terminator(_active_workers, _queues);
4349   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4350 
4351   _workers->run_task(&proc_task_proxy);
4352 }
4353 
4354 // Gang task for parallel reference enqueueing.
4355 
4356 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4357   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4358   EnqueueTask& _enq_task;
4359 
4360 public:
4361   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4362     AbstractGangTask("Enqueue reference objects in parallel"),
4363     _enq_task(enq_task)
4364   { }
4365 
4366   virtual void work(uint worker_id) {
4367     _enq_task.work(worker_id);
4368   }
4369 };
4370 
4371 // Driver routine for parallel reference enqueueing.
4372 // Creates an instance of the ref enqueueing gang
4373 // task and has the worker threads execute it.
4374 
4375 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4376   assert(_workers != NULL, "Need parallel worker threads.");
4377 
4378   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4379 
4380   _workers->run_task(&enq_task_proxy);
4381 }
4382 
4383 // End of weak reference support closures
4384 
4385 // Abstract task used to preserve (i.e. copy) any referent objects
4386 // that are in the collection set and are pointed to by reference
4387 // objects discovered by the CM ref processor.
4388 
4389 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4390 protected:
4391   G1CollectedHeap*         _g1h;
4392   G1ParScanThreadStateSet* _pss;
4393   RefToScanQueueSet*       _queues;
4394   ParallelTaskTerminator   _terminator;
4395   uint                     _n_workers;
4396 
4397 public:
4398   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4399     AbstractGangTask("ParPreserveCMReferents"),
4400     _g1h(g1h),
4401     _pss(per_thread_states),
4402     _queues(task_queues),
4403     _terminator(workers, _queues),
4404     _n_workers(workers)
4405   { }
4406 
4407   void work(uint worker_id) {
4408     ResourceMark rm;
4409     HandleMark   hm;
4410 
4411     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4412     pss->set_ref_processor(NULL);
4413     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4414 
4415     // Is alive closure
4416     G1AlwaysAliveClosure always_alive(_g1h);
4417 
4418     // Copying keep alive closure. Applied to referent objects that need
4419     // to be copied.
4420     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4421 
4422     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4423 
4424     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4425     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4426 
4427     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4428     // So this must be true - but assert just in case someone decides to
4429     // change the worker ids.
4430     assert(worker_id < limit, "sanity");
4431     assert(!rp->discovery_is_atomic(), "check this code");
4432 
4433     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4434     for (uint idx = worker_id; idx < limit; idx += stride) {
4435       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4436 
4437       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4438       while (iter.has_next()) {
4439         // Since discovery is not atomic for the CM ref processor, we
4440         // can see some null referent objects.
4441         iter.load_ptrs(DEBUG_ONLY(true));
4442         oop ref = iter.obj();
4443 
4444         // This will filter nulls.
4445         if (iter.is_referent_alive()) {
4446           iter.make_referent_alive();
4447         }
4448         iter.move_to_next();
4449       }
4450     }
4451 
4452     // Drain the queue - which may cause stealing
4453     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4454     drain_queue.do_void();
4455     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4456     assert(pss->queue_is_empty(), "should be");
4457   }
4458 };
4459 
4460 void G1CollectedHeap::process_weak_jni_handles() {
4461   double ref_proc_start = os::elapsedTime();
4462 
4463   G1STWIsAliveClosure is_alive(this);
4464   G1KeepAliveClosure keep_alive(this);
4465   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4466 
4467   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4468   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4469 }
4470 
4471 // Weak Reference processing during an evacuation pause (part 1).
4472 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4473   double ref_proc_start = os::elapsedTime();
4474 
4475   ReferenceProcessor* rp = _ref_processor_stw;
4476   assert(rp->discovery_enabled(), "should have been enabled");
4477 
4478   // Any reference objects, in the collection set, that were 'discovered'
4479   // by the CM ref processor should have already been copied (either by
4480   // applying the external root copy closure to the discovered lists, or
4481   // by following an RSet entry).
4482   //
4483   // But some of the referents, that are in the collection set, that these
4484   // reference objects point to may not have been copied: the STW ref
4485   // processor would have seen that the reference object had already
4486   // been 'discovered' and would have skipped discovering the reference,
4487   // but would not have treated the reference object as a regular oop.
4488   // As a result the copy closure would not have been applied to the
4489   // referent object.
4490   //
4491   // We need to explicitly copy these referent objects - the references
4492   // will be processed at the end of remarking.
4493   //
4494   // We also need to do this copying before we process the reference
4495   // objects discovered by the STW ref processor in case one of these
4496   // referents points to another object which is also referenced by an
4497   // object discovered by the STW ref processor.
4498 
4499   uint no_of_gc_workers = workers()->active_workers();
4500 
4501   G1ParPreserveCMReferentsTask keep_cm_referents(this,
4502                                                  per_thread_states,
4503                                                  no_of_gc_workers,
4504                                                  _task_queues);
4505 
4506   workers()->run_task(&keep_cm_referents);
4507 
4508   // Closure to test whether a referent is alive.
4509   G1STWIsAliveClosure is_alive(this);
4510 
4511   // Even when parallel reference processing is enabled, the processing
4512   // of JNI refs is serial and performed serially by the current thread
4513   // rather than by a worker. The following PSS will be used for processing
4514   // JNI refs.
4515 
4516   // Use only a single queue for this PSS.
4517   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4518   pss->set_ref_processor(NULL);
4519   assert(pss->queue_is_empty(), "pre-condition");
4520 
4521   // Keep alive closure.
4522   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4523 
4524   // Serial Complete GC closure
4525   G1STWDrainQueueClosure drain_queue(this, pss);
4526 
4527   // Setup the soft refs policy...
4528   rp->setup_policy(false);
4529 
4530   ReferenceProcessorStats stats;
4531   if (!rp->processing_is_mt()) {
4532     // Serial reference processing...
4533     stats = rp->process_discovered_references(&is_alive,
4534                                               &keep_alive,
4535                                               &drain_queue,
4536                                               NULL,
4537                                               _gc_timer_stw);
4538   } else {
4539     // Parallel reference processing
4540     assert(rp->num_q() == no_of_gc_workers, "sanity");
4541     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4542 
4543     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4544     stats = rp->process_discovered_references(&is_alive,
4545                                               &keep_alive,
4546                                               &drain_queue,
4547                                               &par_task_executor,
4548                                               _gc_timer_stw);
4549   }
4550 
4551   _gc_tracer_stw->report_gc_reference_stats(stats);
4552 
4553   // We have completed copying any necessary live referent objects.
4554   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4555 
4556   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4557   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4558 }
4559 
4560 // Weak Reference processing during an evacuation pause (part 2).
4561 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4562   double ref_enq_start = os::elapsedTime();
4563 
4564   ReferenceProcessor* rp = _ref_processor_stw;
4565   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4566 
4567   // Now enqueue any remaining on the discovered lists on to
4568   // the pending list.
4569   if (!rp->processing_is_mt()) {
4570     // Serial reference processing...
4571     rp->enqueue_discovered_references();
4572   } else {
4573     // Parallel reference enqueueing
4574 
4575     uint n_workers = workers()->active_workers();
4576 
4577     assert(rp->num_q() == n_workers, "sanity");
4578     assert(n_workers <= rp->max_num_q(), "sanity");
4579 
4580     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4581     rp->enqueue_discovered_references(&par_task_executor);
4582   }
4583 
4584   rp->verify_no_references_recorded();
4585   assert(!rp->discovery_enabled(), "should have been disabled");
4586 
4587   // FIXME
4588   // CM's reference processing also cleans up the string and symbol tables.
4589   // Should we do that here also? We could, but it is a serial operation
4590   // and could significantly increase the pause time.
4591 
4592   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4593   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4594 }
4595 
4596 void G1CollectedHeap::pre_evacuate_collection_set() {
4597   _expand_heap_after_alloc_failure = true;
4598   _evacuation_failed = false;
4599 
4600   // Disable the hot card cache.
4601   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4602   hot_card_cache->reset_hot_cache_claimed_index();
4603   hot_card_cache->set_use_cache(false);
4604 
4605   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4606 }
4607 
4608 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4609   // Should G1EvacuationFailureALot be in effect for this GC?
4610   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4611 
4612   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4613   double start_par_time_sec = os::elapsedTime();
4614   double end_par_time_sec;
4615 
4616   {
4617     const uint n_workers = workers()->active_workers();
4618     G1RootProcessor root_processor(this, n_workers);
4619     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4620     // InitialMark needs claim bits to keep track of the marked-through CLDs.
4621     if (collector_state()->during_initial_mark_pause()) {
4622       ClassLoaderDataGraph::clear_claimed_marks();
4623     }
4624 
4625     print_termination_stats_hdr();
4626 
4627     workers()->run_task(&g1_par_task);
4628     end_par_time_sec = os::elapsedTime();
4629 
4630     // Closing the inner scope will execute the destructor
4631     // for the G1RootProcessor object. We record the current
4632     // elapsed time before closing the scope so that time
4633     // taken for the destructor is NOT included in the
4634     // reported parallel time.
4635   }
4636 
4637   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4638 
4639   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4640   phase_times->record_par_time(par_time_ms);
4641 
4642   double code_root_fixup_time_ms =
4643         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4644   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4645 }
4646 
4647 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4648   // Process any discovered reference objects - we have
4649   // to do this _before_ we retire the GC alloc regions
4650   // as we may have to copy some 'reachable' referent
4651   // objects (and their reachable sub-graphs) that were
4652   // not copied during the pause.
4653   if (g1_policy()->should_process_references()) {
4654     process_discovered_references(per_thread_states);
4655   } else {
4656     ref_processor_stw()->verify_no_references_recorded();
4657     process_weak_jni_handles();
4658   }
4659 
4660   if (G1StringDedup::is_enabled()) {
4661     double fixup_start = os::elapsedTime();
4662 
4663     G1STWIsAliveClosure is_alive(this);
4664     G1KeepAliveClosure keep_alive(this);
4665     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4666 
4667     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4668     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4669   }
4670 
4671   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4672 
4673   if (evacuation_failed()) {
4674     restore_after_evac_failure();
4675 
4676     // Reset the G1EvacuationFailureALot counters and flags
4677     // Note: the values are reset only when an actual
4678     // evacuation failure occurs.
4679     NOT_PRODUCT(reset_evacuation_should_fail();)
4680   }
4681 
4682   // Enqueue any remaining references remaining on the STW
4683   // reference processor's discovered lists. We need to do
4684   // this after the card table is cleaned (and verified) as
4685   // the act of enqueueing entries on to the pending list
4686   // will log these updates (and dirty their associated
4687   // cards). We need these updates logged to update any
4688   // RSets.
4689   if (g1_policy()->should_process_references()) {
4690     enqueue_discovered_references(per_thread_states);
4691   } else {
4692     g1_policy()->phase_times()->record_ref_enq_time(0);
4693   }
4694 
4695   _allocator->release_gc_alloc_regions(evacuation_info);
4696 
4697   per_thread_states->flush();
4698 
4699   record_obj_copy_mem_stats();
4700 
4701   _survivor_evac_stats.adjust_desired_plab_sz();
4702   _old_evac_stats.adjust_desired_plab_sz();
4703 
4704   // Reset and re-enable the hot card cache.
4705   // Note the counts for the cards in the regions in the
4706   // collection set are reset when the collection set is freed.
4707   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4708   hot_card_cache->reset_hot_cache();
4709   hot_card_cache->set_use_cache(true);
4710 
4711   purge_code_root_memory();
4712 
4713   redirty_logged_cards();
4714 #if defined(COMPILER2) || INCLUDE_JVMCI
4715   DerivedPointerTable::update_pointers();
4716 #endif
4717 }
4718 
4719 void G1CollectedHeap::record_obj_copy_mem_stats() {
4720   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4721 
4722   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4723                                                create_g1_evac_summary(&_old_evac_stats));
4724 }
4725 
4726 void G1CollectedHeap::free_region(HeapRegion* hr,
4727                                   FreeRegionList* free_list,
4728                                   bool par,
4729                                   bool locked) {
4730   assert(!hr->is_free(), "the region should not be free");
4731   assert(!hr->is_empty(), "the region should not be empty");
4732   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4733   assert(free_list != NULL, "pre-condition");
4734 
4735   if (G1VerifyBitmaps) {
4736     MemRegion mr(hr->bottom(), hr->end());
4737     concurrent_mark()->clearRangePrevBitmap(mr);
4738   }
4739 
4740   // Clear the card counts for this region.
4741   // Note: we only need to do this if the region is not young
4742   // (since we don't refine cards in young regions).
4743   if (!hr->is_young()) {
4744     _cg1r->hot_card_cache()->reset_card_counts(hr);
4745   }
4746   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4747   free_list->add_ordered(hr);
4748 }
4749 
4750 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4751                                             FreeRegionList* free_list,
4752                                             bool par) {
4753   assert(hr->is_humongous(), "this is only for humongous regions");
4754   assert(free_list != NULL, "pre-condition");
4755   hr->clear_humongous();
4756   free_region(hr, free_list, par);
4757 }
4758 
4759 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4760                                            const uint humongous_regions_removed) {
4761   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4762     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4763     _old_set.bulk_remove(old_regions_removed);
4764     _humongous_set.bulk_remove(humongous_regions_removed);
4765   }
4766 
4767 }
4768 
4769 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4770   assert(list != NULL, "list can't be null");
4771   if (!list->is_empty()) {
4772     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4773     _hrm.insert_list_into_free_list(list);
4774   }
4775 }
4776 
4777 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4778   decrease_used(bytes);
4779 }
4780 
4781 class G1ParCleanupCTTask : public AbstractGangTask {
4782   G1SATBCardTableModRefBS* _ct_bs;
4783   G1CollectedHeap* _g1h;
4784   HeapRegion* volatile _su_head;
4785 public:
4786   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4787                      G1CollectedHeap* g1h) :
4788     AbstractGangTask("G1 Par Cleanup CT Task"),
4789     _ct_bs(ct_bs), _g1h(g1h) { }
4790 
4791   void work(uint worker_id) {
4792     HeapRegion* r;
4793     while (r = _g1h->pop_dirty_cards_region()) {
4794       clear_cards(r);
4795     }
4796   }
4797 
4798   void clear_cards(HeapRegion* r) {
4799     // Cards of the survivors should have already been dirtied.
4800     if (!r->is_survivor()) {
4801       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4802     }
4803   }
4804 };
4805 
4806 class G1ParScrubRemSetTask: public AbstractGangTask {
4807 protected:
4808   G1RemSet* _g1rs;
4809   BitMap* _region_bm;
4810   BitMap* _card_bm;
4811   HeapRegionClaimer _hrclaimer;
4812 
4813 public:
4814   G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4815     AbstractGangTask("G1 ScrubRS"),
4816     _g1rs(g1_rs),
4817     _region_bm(region_bm),
4818     _card_bm(card_bm),
4819     _hrclaimer(num_workers) {
4820   }
4821 
4822   void work(uint worker_id) {
4823     _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4824   }
4825 };
4826 
4827 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4828   uint num_workers = workers()->active_workers();
4829   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4830   workers()->run_task(&g1_par_scrub_rs_task);
4831 }
4832 
4833 void G1CollectedHeap::cleanUpCardTable() {
4834   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4835   double start = os::elapsedTime();
4836 
4837   {
4838     // Iterate over the dirty cards region list.
4839     G1ParCleanupCTTask cleanup_task(ct_bs, this);
4840 
4841     workers()->run_task(&cleanup_task);
4842 #ifndef PRODUCT
4843     _verifier->verify_card_table_cleanup();
4844 #endif
4845   }
4846 
4847   double elapsed = os::elapsedTime() - start;
4848   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4849 }
4850 
4851 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4852   size_t pre_used = 0;
4853   FreeRegionList local_free_list("Local List for CSet Freeing");
4854 
4855   double young_time_ms     = 0.0;
4856   double non_young_time_ms = 0.0;
4857 
4858   // Since the collection set is a superset of the the young list,
4859   // all we need to do to clear the young list is clear its
4860   // head and length, and unlink any young regions in the code below
4861   _young_list->clear();
4862 
4863   G1CollectorPolicy* policy = g1_policy();
4864 
4865   double start_sec = os::elapsedTime();
4866   bool non_young = true;
4867 
4868   HeapRegion* cur = cs_head;
4869   int age_bound = -1;
4870   size_t rs_lengths = 0;
4871 
4872   while (cur != NULL) {
4873     assert(!is_on_master_free_list(cur), "sanity");
4874     if (non_young) {
4875       if (cur->is_young()) {
4876         double end_sec = os::elapsedTime();
4877         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4878         non_young_time_ms += elapsed_ms;
4879 
4880         start_sec = os::elapsedTime();
4881         non_young = false;
4882       }
4883     } else {
4884       if (!cur->is_young()) {
4885         double end_sec = os::elapsedTime();
4886         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4887         young_time_ms += elapsed_ms;
4888 
4889         start_sec = os::elapsedTime();
4890         non_young = true;
4891       }
4892     }
4893 
4894     rs_lengths += cur->rem_set()->occupied_locked();
4895 
4896     HeapRegion* next = cur->next_in_collection_set();
4897     assert(cur->in_collection_set(), "bad CS");
4898     cur->set_next_in_collection_set(NULL);
4899     clear_in_cset(cur);
4900 
4901     if (cur->is_young()) {
4902       int index = cur->young_index_in_cset();
4903       assert(index != -1, "invariant");
4904       assert((uint) index < policy->young_cset_region_length(), "invariant");
4905       size_t words_survived = surviving_young_words[index];
4906       cur->record_surv_words_in_group(words_survived);
4907 
4908       // At this point the we have 'popped' cur from the collection set
4909       // (linked via next_in_collection_set()) but it is still in the
4910       // young list (linked via next_young_region()). Clear the
4911       // _next_young_region field.
4912       cur->set_next_young_region(NULL);
4913     } else {
4914       int index = cur->young_index_in_cset();
4915       assert(index == -1, "invariant");
4916     }
4917 
4918     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4919             (!cur->is_young() && cur->young_index_in_cset() == -1),
4920             "invariant" );
4921 
4922     if (!cur->evacuation_failed()) {
4923       MemRegion used_mr = cur->used_region();
4924 
4925       // And the region is empty.
4926       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4927       pre_used += cur->used();
4928       free_region(cur, &local_free_list, false /* par */, true /* locked */);
4929     } else {
4930       cur->uninstall_surv_rate_group();
4931       if (cur->is_young()) {
4932         cur->set_young_index_in_cset(-1);
4933       }
4934       cur->set_evacuation_failed(false);
4935       // When moving a young gen region to old gen, we "allocate" that whole region
4936       // there. This is in addition to any already evacuated objects. Notify the
4937       // policy about that.
4938       // Old gen regions do not cause an additional allocation: both the objects
4939       // still in the region and the ones already moved are accounted for elsewhere.
4940       if (cur->is_young()) {
4941         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4942       }
4943       // The region is now considered to be old.
4944       cur->set_old();
4945       // Do some allocation statistics accounting. Regions that failed evacuation
4946       // are always made old, so there is no need to update anything in the young
4947       // gen statistics, but we need to update old gen statistics.
4948       size_t used_words = cur->marked_bytes() / HeapWordSize;
4949       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4950       _old_set.add(cur);
4951       evacuation_info.increment_collectionset_used_after(cur->used());
4952     }
4953     cur = next;
4954   }
4955 
4956   evacuation_info.set_regions_freed(local_free_list.length());
4957   policy->record_max_rs_lengths(rs_lengths);
4958   policy->cset_regions_freed();
4959 
4960   double end_sec = os::elapsedTime();
4961   double elapsed_ms = (end_sec - start_sec) * 1000.0;
4962 
4963   if (non_young) {
4964     non_young_time_ms += elapsed_ms;
4965   } else {
4966     young_time_ms += elapsed_ms;
4967   }
4968 
4969   prepend_to_freelist(&local_free_list);
4970   decrement_summary_bytes(pre_used);
4971   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4972   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4973 }
4974 
4975 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4976  private:
4977   FreeRegionList* _free_region_list;
4978   HeapRegionSet* _proxy_set;
4979   uint _humongous_regions_removed;
4980   size_t _freed_bytes;
4981  public:
4982 
4983   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4984     _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4985   }
4986 
4987   virtual bool doHeapRegion(HeapRegion* r) {
4988     if (!r->is_starts_humongous()) {
4989       return false;
4990     }
4991 
4992     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4993 
4994     oop obj = (oop)r->bottom();
4995     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4996 
4997     // The following checks whether the humongous object is live are sufficient.
4998     // The main additional check (in addition to having a reference from the roots
4999     // or the young gen) is whether the humongous object has a remembered set entry.
5000     //
5001     // A humongous object cannot be live if there is no remembered set for it
5002     // because:
5003     // - there can be no references from within humongous starts regions referencing
5004     // the object because we never allocate other objects into them.
5005     // (I.e. there are no intra-region references that may be missed by the
5006     // remembered set)
5007     // - as soon there is a remembered set entry to the humongous starts region
5008     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5009     // until the end of a concurrent mark.
5010     //
5011     // It is not required to check whether the object has been found dead by marking
5012     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5013     // all objects allocated during that time are considered live.
5014     // SATB marking is even more conservative than the remembered set.
5015     // So if at this point in the collection there is no remembered set entry,
5016     // nobody has a reference to it.
5017     // At the start of collection we flush all refinement logs, and remembered sets
5018     // are completely up-to-date wrt to references to the humongous object.
5019     //
5020     // Other implementation considerations:
5021     // - never consider object arrays at this time because they would pose
5022     // considerable effort for cleaning up the the remembered sets. This is
5023     // required because stale remembered sets might reference locations that
5024     // are currently allocated into.
5025     uint region_idx = r->hrm_index();
5026     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5027         !r->rem_set()->is_empty()) {
5028       log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT "  with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5029                                region_idx,
5030                                (size_t)obj->size() * HeapWordSize,
5031                                p2i(r->bottom()),
5032                                r->rem_set()->occupied(),
5033                                r->rem_set()->strong_code_roots_list_length(),
5034                                next_bitmap->isMarked(r->bottom()),
5035                                g1h->is_humongous_reclaim_candidate(region_idx),
5036                                obj->is_typeArray()
5037                               );
5038       return false;
5039     }
5040 
5041     guarantee(obj->is_typeArray(),
5042               "Only eagerly reclaiming type arrays is supported, but the object "
5043               PTR_FORMAT " is not.", p2i(r->bottom()));
5044 
5045     log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5046                              region_idx,
5047                              (size_t)obj->size() * HeapWordSize,
5048                              p2i(r->bottom()),
5049                              r->rem_set()->occupied(),
5050                              r->rem_set()->strong_code_roots_list_length(),
5051                              next_bitmap->isMarked(r->bottom()),
5052                              g1h->is_humongous_reclaim_candidate(region_idx),
5053                              obj->is_typeArray()
5054                             );
5055 
5056     // Need to clear mark bit of the humongous object if already set.
5057     if (next_bitmap->isMarked(r->bottom())) {
5058       next_bitmap->clear(r->bottom());
5059     }
5060     do {
5061       HeapRegion* next = g1h->next_region_in_humongous(r);
5062       _freed_bytes += r->used();
5063       r->set_containing_set(NULL);
5064       _humongous_regions_removed++;
5065       g1h->free_humongous_region(r, _free_region_list, false);
5066       r = next;
5067     } while (r != NULL);
5068 
5069     return false;
5070   }
5071 
5072   uint humongous_free_count() {
5073     return _humongous_regions_removed;
5074   }
5075 
5076   size_t bytes_freed() const {
5077     return _freed_bytes;
5078   }
5079 };
5080 
5081 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5082   assert_at_safepoint(true);
5083 
5084   if (!G1EagerReclaimHumongousObjects ||
5085       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5086     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5087     return;
5088   }
5089 
5090   double start_time = os::elapsedTime();
5091 
5092   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5093 
5094   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5095   heap_region_iterate(&cl);
5096 
5097   remove_from_old_sets(0, cl.humongous_free_count());
5098 
5099   G1HRPrinter* hrp = hr_printer();
5100   if (hrp->is_active()) {
5101     FreeRegionListIterator iter(&local_cleanup_list);
5102     while (iter.more_available()) {
5103       HeapRegion* hr = iter.get_next();
5104       hrp->cleanup(hr);
5105     }
5106   }
5107 
5108   prepend_to_freelist(&local_cleanup_list);
5109   decrement_summary_bytes(cl.bytes_freed());
5110 
5111   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5112                                                                     cl.humongous_free_count());
5113 }
5114 
5115 // This routine is similar to the above but does not record
5116 // any policy statistics or update free lists; we are abandoning
5117 // the current incremental collection set in preparation of a
5118 // full collection. After the full GC we will start to build up
5119 // the incremental collection set again.
5120 // This is only called when we're doing a full collection
5121 // and is immediately followed by the tearing down of the young list.
5122 
5123 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5124   HeapRegion* cur = cs_head;
5125 
5126   while (cur != NULL) {
5127     HeapRegion* next = cur->next_in_collection_set();
5128     assert(cur->in_collection_set(), "bad CS");
5129     cur->set_next_in_collection_set(NULL);
5130     clear_in_cset(cur);
5131     cur->set_young_index_in_cset(-1);
5132     cur = next;
5133   }
5134 }
5135 
5136 void G1CollectedHeap::set_free_regions_coming() {
5137   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5138 
5139   assert(!free_regions_coming(), "pre-condition");
5140   _free_regions_coming = true;
5141 }
5142 
5143 void G1CollectedHeap::reset_free_regions_coming() {
5144   assert(free_regions_coming(), "pre-condition");
5145 
5146   {
5147     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5148     _free_regions_coming = false;
5149     SecondaryFreeList_lock->notify_all();
5150   }
5151 
5152   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5153 }
5154 
5155 void G1CollectedHeap::wait_while_free_regions_coming() {
5156   // Most of the time we won't have to wait, so let's do a quick test
5157   // first before we take the lock.
5158   if (!free_regions_coming()) {
5159     return;
5160   }
5161 
5162   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5163 
5164   {
5165     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5166     while (free_regions_coming()) {
5167       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5168     }
5169   }
5170 
5171   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5172 }
5173 
5174 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5175   return _allocator->is_retained_old_region(hr);
5176 }
5177 
5178 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5179   _young_list->push_region(hr);
5180 }
5181 
5182 class NoYoungRegionsClosure: public HeapRegionClosure {
5183 private:
5184   bool _success;
5185 public:
5186   NoYoungRegionsClosure() : _success(true) { }
5187   bool doHeapRegion(HeapRegion* r) {
5188     if (r->is_young()) {
5189       log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5190                            p2i(r->bottom()), p2i(r->end()));
5191       _success = false;
5192     }
5193     return false;
5194   }
5195   bool success() { return _success; }
5196 };
5197 
5198 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5199   bool ret = _young_list->check_list_empty(check_sample);
5200 
5201   if (check_heap) {
5202     NoYoungRegionsClosure closure;
5203     heap_region_iterate(&closure);
5204     ret = ret && closure.success();
5205   }
5206 
5207   return ret;
5208 }
5209 
5210 class TearDownRegionSetsClosure : public HeapRegionClosure {
5211 private:
5212   HeapRegionSet *_old_set;
5213 
5214 public:
5215   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5216 
5217   bool doHeapRegion(HeapRegion* r) {
5218     if (r->is_old()) {
5219       _old_set->remove(r);
5220     } else {
5221       // We ignore free regions, we'll empty the free list afterwards.
5222       // We ignore young regions, we'll empty the young list afterwards.
5223       // We ignore humongous regions, we're not tearing down the
5224       // humongous regions set.
5225       assert(r->is_free() || r->is_young() || r->is_humongous(),
5226              "it cannot be another type");
5227     }
5228     return false;
5229   }
5230 
5231   ~TearDownRegionSetsClosure() {
5232     assert(_old_set->is_empty(), "post-condition");
5233   }
5234 };
5235 
5236 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5237   assert_at_safepoint(true /* should_be_vm_thread */);
5238 
5239   if (!free_list_only) {
5240     TearDownRegionSetsClosure cl(&_old_set);
5241     heap_region_iterate(&cl);
5242 
5243     // Note that emptying the _young_list is postponed and instead done as
5244     // the first step when rebuilding the regions sets again. The reason for
5245     // this is that during a full GC string deduplication needs to know if
5246     // a collected region was young or old when the full GC was initiated.
5247   }
5248   _hrm.remove_all_free_regions();
5249 }
5250 
5251 void G1CollectedHeap::increase_used(size_t bytes) {
5252   _summary_bytes_used += bytes;
5253 }
5254 
5255 void G1CollectedHeap::decrease_used(size_t bytes) {
5256   assert(_summary_bytes_used >= bytes,
5257          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5258          _summary_bytes_used, bytes);
5259   _summary_bytes_used -= bytes;
5260 }
5261 
5262 void G1CollectedHeap::set_used(size_t bytes) {
5263   _summary_bytes_used = bytes;
5264 }
5265 
5266 class RebuildRegionSetsClosure : public HeapRegionClosure {
5267 private:
5268   bool            _free_list_only;
5269   HeapRegionSet*   _old_set;
5270   HeapRegionManager*   _hrm;
5271   size_t          _total_used;
5272 
5273 public:
5274   RebuildRegionSetsClosure(bool free_list_only,
5275                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5276     _free_list_only(free_list_only),
5277     _old_set(old_set), _hrm(hrm), _total_used(0) {
5278     assert(_hrm->num_free_regions() == 0, "pre-condition");
5279     if (!free_list_only) {
5280       assert(_old_set->is_empty(), "pre-condition");
5281     }
5282   }
5283 
5284   bool doHeapRegion(HeapRegion* r) {
5285     if (r->is_empty()) {
5286       // Add free regions to the free list
5287       r->set_free();
5288       r->set_allocation_context(AllocationContext::system());
5289       _hrm->insert_into_free_list(r);
5290     } else if (!_free_list_only) {
5291       assert(!r->is_young(), "we should not come across young regions");
5292 
5293       if (r->is_humongous()) {
5294         // We ignore humongous regions. We left the humongous set unchanged.
5295       } else {
5296         // Objects that were compacted would have ended up on regions
5297         // that were previously old or free.  Archive regions (which are
5298         // old) will not have been touched.
5299         assert(r->is_free() || r->is_old(), "invariant");
5300         // We now consider them old, so register as such. Leave
5301         // archive regions set that way, however, while still adding
5302         // them to the old set.
5303         if (!r->is_archive()) {
5304           r->set_old();
5305         }
5306         _old_set->add(r);
5307       }
5308       _total_used += r->used();
5309     }
5310 
5311     return false;
5312   }
5313 
5314   size_t total_used() {
5315     return _total_used;
5316   }
5317 };
5318 
5319 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5320   assert_at_safepoint(true /* should_be_vm_thread */);
5321 
5322   if (!free_list_only) {
5323     _young_list->empty_list();
5324   }
5325 
5326   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5327   heap_region_iterate(&cl);
5328 
5329   if (!free_list_only) {
5330     set_used(cl.total_used());
5331     if (_archive_allocator != NULL) {
5332       _archive_allocator->clear_used();
5333     }
5334   }
5335   assert(used_unlocked() == recalculate_used(),
5336          "inconsistent used_unlocked(), "
5337          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5338          used_unlocked(), recalculate_used());
5339 }
5340 
5341 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5342   _refine_cte_cl->set_concurrent(concurrent);
5343 }
5344 
5345 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5346   HeapRegion* hr = heap_region_containing(p);
5347   return hr->is_in(p);
5348 }
5349 
5350 // Methods for the mutator alloc region
5351 
5352 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5353                                                       bool force) {
5354   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5355   assert(!force || g1_policy()->can_expand_young_list(),
5356          "if force is true we should be able to expand the young list");
5357   bool young_list_full = g1_policy()->is_young_list_full();
5358   if (force || !young_list_full) {
5359     HeapRegion* new_alloc_region = new_region(word_size,
5360                                               false /* is_old */,
5361                                               false /* do_expand */);
5362     if (new_alloc_region != NULL) {
5363       set_region_short_lived_locked(new_alloc_region);
5364       _hr_printer.alloc(new_alloc_region, young_list_full);
5365       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5366       return new_alloc_region;
5367     }
5368   }
5369   return NULL;
5370 }
5371 
5372 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5373                                                   size_t allocated_bytes) {
5374   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5375   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5376 
5377   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5378   increase_used(allocated_bytes);
5379   _hr_printer.retire(alloc_region);
5380   // We update the eden sizes here, when the region is retired,
5381   // instead of when it's allocated, since this is the point that its
5382   // used space has been recored in _summary_bytes_used.
5383   g1mm()->update_eden_size();
5384 }
5385 
5386 // Methods for the GC alloc regions
5387 
5388 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5389                                                  uint count,
5390                                                  InCSetState dest) {
5391   assert(FreeList_lock->owned_by_self(), "pre-condition");
5392 
5393   if (count < g1_policy()->max_regions(dest)) {
5394     const bool is_survivor = (dest.is_young());
5395     HeapRegion* new_alloc_region = new_region(word_size,
5396                                               !is_survivor,
5397                                               true /* do_expand */);
5398     if (new_alloc_region != NULL) {
5399       // We really only need to do this for old regions given that we
5400       // should never scan survivors. But it doesn't hurt to do it
5401       // for survivors too.
5402       new_alloc_region->record_timestamp();
5403       if (is_survivor) {
5404         new_alloc_region->set_survivor();
5405         _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5406       } else {
5407         new_alloc_region->set_old();
5408         _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5409       }
5410       _hr_printer.alloc(new_alloc_region);
5411       bool during_im = collector_state()->during_initial_mark_pause();
5412       new_alloc_region->note_start_of_copying(during_im);
5413       return new_alloc_region;
5414     }
5415   }
5416   return NULL;
5417 }
5418 
5419 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5420                                              size_t allocated_bytes,
5421                                              InCSetState dest) {
5422   bool during_im = collector_state()->during_initial_mark_pause();
5423   alloc_region->note_end_of_copying(during_im);
5424   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5425   if (dest.is_young()) {
5426     young_list()->add_survivor_region(alloc_region);
5427   } else {
5428     _old_set.add(alloc_region);
5429   }
5430   _hr_printer.retire(alloc_region);
5431 }
5432 
5433 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5434   bool expanded = false;
5435   uint index = _hrm.find_highest_free(&expanded);
5436 
5437   if (index != G1_NO_HRM_INDEX) {
5438     if (expanded) {
5439       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5440                                 HeapRegion::GrainWords * HeapWordSize);
5441     }
5442     _hrm.allocate_free_regions_starting_at(index, 1);
5443     return region_at(index);
5444   }
5445   return NULL;
5446 }
5447 
5448 // Optimized nmethod scanning
5449 
5450 class RegisterNMethodOopClosure: public OopClosure {
5451   G1CollectedHeap* _g1h;
5452   nmethod* _nm;
5453 
5454   template <class T> void do_oop_work(T* p) {
5455     T heap_oop = oopDesc::load_heap_oop(p);
5456     if (!oopDesc::is_null(heap_oop)) {
5457       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5458       HeapRegion* hr = _g1h->heap_region_containing(obj);
5459       assert(!hr->is_continues_humongous(),
5460              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5461              " starting at " HR_FORMAT,
5462              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5463 
5464       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5465       hr->add_strong_code_root_locked(_nm);
5466     }
5467   }
5468 
5469 public:
5470   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5471     _g1h(g1h), _nm(nm) {}
5472 
5473   void do_oop(oop* p)       { do_oop_work(p); }
5474   void do_oop(narrowOop* p) { do_oop_work(p); }
5475 };
5476 
5477 class UnregisterNMethodOopClosure: public OopClosure {
5478   G1CollectedHeap* _g1h;
5479   nmethod* _nm;
5480 
5481   template <class T> void do_oop_work(T* p) {
5482     T heap_oop = oopDesc::load_heap_oop(p);
5483     if (!oopDesc::is_null(heap_oop)) {
5484       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5485       HeapRegion* hr = _g1h->heap_region_containing(obj);
5486       assert(!hr->is_continues_humongous(),
5487              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5488              " starting at " HR_FORMAT,
5489              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5490 
5491       hr->remove_strong_code_root(_nm);
5492     }
5493   }
5494 
5495 public:
5496   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5497     _g1h(g1h), _nm(nm) {}
5498 
5499   void do_oop(oop* p)       { do_oop_work(p); }
5500   void do_oop(narrowOop* p) { do_oop_work(p); }
5501 };
5502 
5503 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5504   CollectedHeap::register_nmethod(nm);
5505 
5506   guarantee(nm != NULL, "sanity");
5507   RegisterNMethodOopClosure reg_cl(this, nm);
5508   nm->oops_do(&reg_cl);
5509 }
5510 
5511 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5512   CollectedHeap::unregister_nmethod(nm);
5513 
5514   guarantee(nm != NULL, "sanity");
5515   UnregisterNMethodOopClosure reg_cl(this, nm);
5516   nm->oops_do(&reg_cl, true);
5517 }
5518 
5519 void G1CollectedHeap::purge_code_root_memory() {
5520   double purge_start = os::elapsedTime();
5521   G1CodeRootSet::purge();
5522   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5523   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5524 }
5525 
5526 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5527   G1CollectedHeap* _g1h;
5528 
5529 public:
5530   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5531     _g1h(g1h) {}
5532 
5533   void do_code_blob(CodeBlob* cb) {
5534     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5535     if (nm == NULL) {
5536       return;
5537     }
5538 
5539     if (ScavengeRootsInCode) {
5540       _g1h->register_nmethod(nm);
5541     }
5542   }
5543 };
5544 
5545 void G1CollectedHeap::rebuild_strong_code_roots() {
5546   RebuildStrongCodeRootClosure blob_cl(this);
5547   CodeCache::blobs_do(&blob_cl);
5548 }
--- EOF ---