1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "code/icBuffer.hpp"
  30 #include "gc/g1/bufferingOopClosure.hpp"
  31 #include "gc/g1/concurrentG1Refine.hpp"
  32 #include "gc/g1/concurrentG1RefineThread.hpp"
  33 #include "gc/g1/concurrentMarkThread.inline.hpp"
  34 #include "gc/g1/g1Allocator.inline.hpp"
  35 #include "gc/g1/g1CollectedHeap.inline.hpp"
  36 #include "gc/g1/g1CollectorPolicy.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ErgoVerbose.hpp"
  39 #include "gc/g1/g1EvacFailure.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1GCPhaseTimes.hpp"
  42 #include "gc/g1/g1Log.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.hpp"
  63 #include "gc/shared/generationSpec.hpp"
  64 #include "gc/shared/isGCActiveMark.hpp"
  65 #include "gc/shared/referenceProcessor.hpp"
  66 #include "gc/shared/taskqueue.inline.hpp"
  67 #include "memory/allocation.hpp"
  68 #include "memory/iterator.hpp"
  69 #include "oops/oop.inline.hpp"
  70 #include "runtime/atomic.inline.hpp"
  71 #include "runtime/init.hpp"
  72 #include "runtime/orderAccess.inline.hpp"
  73 #include "runtime/vmThread.hpp"
  74 #include "utilities/globalDefinitions.hpp"
  75 #include "utilities/stack.inline.hpp"
  76 
  77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  78 
  79 // INVARIANTS/NOTES
  80 //
  81 // All allocation activity covered by the G1CollectedHeap interface is
  82 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  83 // and allocate_new_tlab, which are the "entry" points to the
  84 // allocation code from the rest of the JVM.  (Note that this does not
  85 // apply to TLAB allocation, which is not part of this interface: it
  86 // is done by clients of this interface.)
  87 
  88 // Local to this file.
  89 
  90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  91   bool _concurrent;
  92 public:
  93   RefineCardTableEntryClosure() : _concurrent(true) { }
  94 
  95   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  96     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
  97     // This path is executed by the concurrent refine or mutator threads,
  98     // concurrently, and so we do not care if card_ptr contains references
  99     // that point into the collection set.
 100     assert(!oops_into_cset, "should be");
 101 
 102     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 103       // Caller will actually yield.
 104       return false;
 105     }
 106     // Otherwise, we finished successfully; return true.
 107     return true;
 108   }
 109 
 110   void set_concurrent(bool b) { _concurrent = b; }
 111 };
 112 
 113 
 114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 115  private:
 116   size_t _num_processed;
 117 
 118  public:
 119   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 120 
 121   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 122     *card_ptr = CardTableModRefBS::dirty_card_val();
 123     _num_processed++;
 124     return true;
 125   }
 126 
 127   size_t num_processed() const { return _num_processed; }
 128 };
 129 
 130 
 131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 132   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 133 }
 134 
 135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 136   // The from card cache is not the memory that is actually committed. So we cannot
 137   // take advantage of the zero_filled parameter.
 138   reset_from_card_cache(start_idx, num_regions);
 139 }
 140 
 141 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 142 {
 143   // Claim the right to put the region on the dirty cards region list
 144   // by installing a self pointer.
 145   HeapRegion* next = hr->get_next_dirty_cards_region();
 146   if (next == NULL) {
 147     HeapRegion* res = (HeapRegion*)
 148       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 149                           NULL);
 150     if (res == NULL) {
 151       HeapRegion* head;
 152       do {
 153         // Put the region to the dirty cards region list.
 154         head = _dirty_cards_region_list;
 155         next = (HeapRegion*)
 156           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 157         if (next == head) {
 158           assert(hr->get_next_dirty_cards_region() == hr,
 159                  "hr->get_next_dirty_cards_region() != hr");
 160           if (next == NULL) {
 161             // The last region in the list points to itself.
 162             hr->set_next_dirty_cards_region(hr);
 163           } else {
 164             hr->set_next_dirty_cards_region(next);
 165           }
 166         }
 167       } while (next != head);
 168     }
 169   }
 170 }
 171 
 172 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 173 {
 174   HeapRegion* head;
 175   HeapRegion* hr;
 176   do {
 177     head = _dirty_cards_region_list;
 178     if (head == NULL) {
 179       return NULL;
 180     }
 181     HeapRegion* new_head = head->get_next_dirty_cards_region();
 182     if (head == new_head) {
 183       // The last region.
 184       new_head = NULL;
 185     }
 186     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 187                                           head);
 188   } while (hr != head);
 189   assert(hr != NULL, "invariant");
 190   hr->set_next_dirty_cards_region(NULL);
 191   return hr;
 192 }
 193 
 194 // Returns true if the reference points to an object that
 195 // can move in an incremental collection.
 196 bool G1CollectedHeap::is_scavengable(const void* p) {
 197   HeapRegion* hr = heap_region_containing(p);
 198   return !hr->is_pinned();
 199 }
 200 
 201 // Private methods.
 202 
 203 HeapRegion*
 204 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 205   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 206   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 207     if (!_secondary_free_list.is_empty()) {
 208       if (G1ConcRegionFreeingVerbose) {
 209         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 210                                "secondary_free_list has %u entries",
 211                                _secondary_free_list.length());
 212       }
 213       // It looks as if there are free regions available on the
 214       // secondary_free_list. Let's move them to the free_list and try
 215       // again to allocate from it.
 216       append_secondary_free_list();
 217 
 218       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 219              "empty we should have moved at least one entry to the free_list");
 220       HeapRegion* res = _hrm.allocate_free_region(is_old);
 221       if (G1ConcRegionFreeingVerbose) {
 222         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 223                                "allocated " HR_FORMAT " from secondary_free_list",
 224                                HR_FORMAT_PARAMS(res));
 225       }
 226       return res;
 227     }
 228 
 229     // Wait here until we get notified either when (a) there are no
 230     // more free regions coming or (b) some regions have been moved on
 231     // the secondary_free_list.
 232     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 233   }
 234 
 235   if (G1ConcRegionFreeingVerbose) {
 236     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 237                            "could not allocate from secondary_free_list");
 238   }
 239   return NULL;
 240 }
 241 
 242 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 243   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 244          "the only time we use this to allocate a humongous region is "
 245          "when we are allocating a single humongous region");
 246 
 247   HeapRegion* res;
 248   if (G1StressConcRegionFreeing) {
 249     if (!_secondary_free_list.is_empty()) {
 250       if (G1ConcRegionFreeingVerbose) {
 251         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 252                                "forced to look at the secondary_free_list");
 253       }
 254       res = new_region_try_secondary_free_list(is_old);
 255       if (res != NULL) {
 256         return res;
 257       }
 258     }
 259   }
 260 
 261   res = _hrm.allocate_free_region(is_old);
 262 
 263   if (res == NULL) {
 264     if (G1ConcRegionFreeingVerbose) {
 265       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 266                              "res == NULL, trying the secondary_free_list");
 267     }
 268     res = new_region_try_secondary_free_list(is_old);
 269   }
 270   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 271     // Currently, only attempts to allocate GC alloc regions set
 272     // do_expand to true. So, we should only reach here during a
 273     // safepoint. If this assumption changes we might have to
 274     // reconsider the use of _expand_heap_after_alloc_failure.
 275     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 276 
 277     ergo_verbose1(ErgoHeapSizing,
 278                   "attempt heap expansion",
 279                   ergo_format_reason("region allocation request failed")
 280                   ergo_format_byte("allocation request"),
 281                   word_size * HeapWordSize);
 282     if (expand(word_size * HeapWordSize)) {
 283       // Given that expand() succeeded in expanding the heap, and we
 284       // always expand the heap by an amount aligned to the heap
 285       // region size, the free list should in theory not be empty.
 286       // In either case allocate_free_region() will check for NULL.
 287       res = _hrm.allocate_free_region(is_old);
 288     } else {
 289       _expand_heap_after_alloc_failure = false;
 290     }
 291   }
 292   return res;
 293 }
 294 
 295 HeapWord*
 296 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 297                                                            uint num_regions,
 298                                                            size_t word_size,
 299                                                            AllocationContext_t context) {
 300   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 301   assert(is_humongous(word_size), "word_size should be humongous");
 302   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 303 
 304   // Index of last region in the series + 1.
 305   uint last = first + num_regions;
 306 
 307   // We need to initialize the region(s) we just discovered. This is
 308   // a bit tricky given that it can happen concurrently with
 309   // refinement threads refining cards on these regions and
 310   // potentially wanting to refine the BOT as they are scanning
 311   // those cards (this can happen shortly after a cleanup; see CR
 312   // 6991377). So we have to set up the region(s) carefully and in
 313   // a specific order.
 314 
 315   // The word size sum of all the regions we will allocate.
 316   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 317   assert(word_size <= word_size_sum, "sanity");
 318 
 319   // This will be the "starts humongous" region.
 320   HeapRegion* first_hr = region_at(first);
 321   // The header of the new object will be placed at the bottom of
 322   // the first region.
 323   HeapWord* new_obj = first_hr->bottom();
 324   // This will be the new top of the new object.
 325   HeapWord* obj_top = new_obj + word_size;
 326 
 327   // First, we need to zero the header of the space that we will be
 328   // allocating. When we update top further down, some refinement
 329   // threads might try to scan the region. By zeroing the header we
 330   // ensure that any thread that will try to scan the region will
 331   // come across the zero klass word and bail out.
 332   //
 333   // NOTE: It would not have been correct to have used
 334   // CollectedHeap::fill_with_object() and make the space look like
 335   // an int array. The thread that is doing the allocation will
 336   // later update the object header to a potentially different array
 337   // type and, for a very short period of time, the klass and length
 338   // fields will be inconsistent. This could cause a refinement
 339   // thread to calculate the object size incorrectly.
 340   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 341 
 342   size_t fill_size = word_size_sum - word_size;
 343   if (fill_size >= min_fill_size()) {
 344     fill_with_objects(obj_top, fill_size);
 345   } else {
 346     fill_size = 0;
 347   }
 348 
 349   // We will set up the first region as "starts humongous". This
 350   // will also update the BOT covering all the regions to reflect
 351   // that there is a single object that starts at the bottom of the
 352   // first region.
 353   first_hr->set_starts_humongous(obj_top, fill_size);
 354   first_hr->set_allocation_context(context);
 355   // Then, if there are any, we will set up the "continues
 356   // humongous" regions.
 357   HeapRegion* hr = NULL;
 358   for (uint i = first + 1; i < last; ++i) {
 359     hr = region_at(i);
 360     hr->set_continues_humongous(first_hr);
 361     hr->set_allocation_context(context);
 362   }
 363 
 364   // Up to this point no concurrent thread would have been able to
 365   // do any scanning on any region in this series. All the top
 366   // fields still point to bottom, so the intersection between
 367   // [bottom,top] and [card_start,card_end] will be empty. Before we
 368   // update the top fields, we'll do a storestore to make sure that
 369   // no thread sees the update to top before the zeroing of the
 370   // object header and the BOT initialization.
 371   OrderAccess::storestore();
 372 
 373   // Now that the BOT and the object header have been initialized,
 374   // we can update top of the "starts humongous" region.
 375   first_hr->set_top(first_hr->end());
 376   if (_hr_printer.is_active()) {
 377     _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->end());
 378   }
 379 
 380   // Now, we will update the top fields of the "continues humongous"
 381   // regions.
 382   hr = NULL;
 383   for (uint i = first + 1; i < last; ++i) {
 384     hr = region_at(i);
 385     hr->set_top(hr->end());
 386     if (_hr_printer.is_active()) {
 387       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 388     }
 389   }
 390 
 391   assert(hr == NULL || (hr->bottom() < obj_top && obj_top <= hr->end()),
 392          "obj_top should be in last region");
 393 
 394   check_bitmaps("Humongous Region Allocation", first_hr);
 395 
 396   increase_used(word_size_sum * HeapWordSize);
 397 
 398   for (uint i = first; i < last; ++i) {
 399     _humongous_set.add(region_at(i));
 400   }
 401 
 402   return new_obj;
 403 }
 404 
 405 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 406   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);  
 407   return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 408 }
 409 
 410 // If could fit into free regions w/o expansion, try.
 411 // Otherwise, if can expand, do so.
 412 // Otherwise, if using ex regions might help, try with ex given back.
 413 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 414   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 415 
 416   verify_region_sets_optional();
 417 
 418   uint first = G1_NO_HRM_INDEX;
 419   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 420 
 421   if (obj_regions == 1) {
 422     // Only one region to allocate, try to use a fast path by directly allocating
 423     // from the free lists. Do not try to expand here, we will potentially do that
 424     // later.
 425     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 426     if (hr != NULL) {
 427       first = hr->hrm_index();
 428     }
 429   } else {
 430     // We can't allocate humongous regions spanning more than one region while
 431     // cleanupComplete() is running, since some of the regions we find to be
 432     // empty might not yet be added to the free list. It is not straightforward
 433     // to know in which list they are on so that we can remove them. We only
 434     // need to do this if we need to allocate more than one region to satisfy the
 435     // current humongous allocation request. If we are only allocating one region
 436     // we use the one-region region allocation code (see above), that already
 437     // potentially waits for regions from the secondary free list.
 438     wait_while_free_regions_coming();
 439     append_secondary_free_list_if_not_empty_with_lock();
 440 
 441     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 442     // are lucky enough to find some.
 443     first = _hrm.find_contiguous_only_empty(obj_regions);
 444     if (first != G1_NO_HRM_INDEX) {
 445       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 446     }
 447   }
 448 
 449   if (first == G1_NO_HRM_INDEX) {
 450     // Policy: We could not find enough regions for the humongous object in the
 451     // free list. Look through the heap to find a mix of free and uncommitted regions.
 452     // If so, try expansion.
 453     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 454     if (first != G1_NO_HRM_INDEX) {
 455       // We found something. Make sure these regions are committed, i.e. expand
 456       // the heap. Alternatively we could do a defragmentation GC.
 457       ergo_verbose1(ErgoHeapSizing,
 458                     "attempt heap expansion",
 459                     ergo_format_reason("humongous allocation request failed")
 460                     ergo_format_byte("allocation request"),
 461                     word_size * HeapWordSize);
 462 
 463       _hrm.expand_at(first, obj_regions);
 464       g1_policy()->record_new_heap_size(num_regions());
 465 
 466 #ifdef ASSERT
 467       for (uint i = first; i < first + obj_regions; ++i) {
 468         HeapRegion* hr = region_at(i);
 469         assert(hr->is_free(), "sanity");
 470         assert(hr->is_empty(), "sanity");
 471         assert(is_on_master_free_list(hr), "sanity");
 472       }
 473 #endif
 474       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 475     } else {
 476       // Policy: Potentially trigger a defragmentation GC.
 477     }
 478   }
 479 
 480   HeapWord* result = NULL;
 481   if (first != G1_NO_HRM_INDEX) {
 482     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 483                                                        word_size, context);
 484     assert(result != NULL, "it should always return a valid result");
 485 
 486     // A successful humongous object allocation changes the used space
 487     // information of the old generation so we need to recalculate the
 488     // sizes and update the jstat counters here.
 489     g1mm()->update_sizes();
 490   }
 491 
 492   verify_region_sets_optional();
 493 
 494   return result;
 495 }
 496 
 497 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 498   assert_heap_not_locked_and_not_at_safepoint();
 499   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 500 
 501   uint dummy_gc_count_before;
 502   uint dummy_gclocker_retry_count = 0;
 503   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 504 }
 505 
 506 HeapWord*
 507 G1CollectedHeap::mem_allocate(size_t word_size,
 508                               bool*  gc_overhead_limit_was_exceeded) {
 509   assert_heap_not_locked_and_not_at_safepoint();
 510 
 511   // Loop until the allocation is satisfied, or unsatisfied after GC.
 512   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 513     uint gc_count_before;
 514 
 515     HeapWord* result = NULL;
 516     if (!is_humongous(word_size)) {
 517       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 518     } else {
 519       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 520     }
 521     if (result != NULL) {
 522       return result;
 523     }
 524 
 525     // Create the garbage collection operation...
 526     VM_G1CollectForAllocation op(gc_count_before, word_size);
 527     op.set_allocation_context(AllocationContext::current());
 528 
 529     // ...and get the VM thread to execute it.
 530     VMThread::execute(&op);
 531 
 532     if (op.prologue_succeeded() && op.pause_succeeded()) {
 533       // If the operation was successful we'll return the result even
 534       // if it is NULL. If the allocation attempt failed immediately
 535       // after a Full GC, it's unlikely we'll be able to allocate now.
 536       HeapWord* result = op.result();
 537       if (result != NULL && !is_humongous(word_size)) {
 538         // Allocations that take place on VM operations do not do any
 539         // card dirtying and we have to do it here. We only have to do
 540         // this for non-humongous allocations, though.
 541         dirty_young_block(result, word_size);
 542       }
 543       return result;
 544     } else {
 545       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 546         return NULL;
 547       }
 548       assert(op.result() == NULL,
 549              "the result should be NULL if the VM op did not succeed");
 550     }
 551 
 552     // Give a warning if we seem to be looping forever.
 553     if ((QueuedAllocationWarningCount > 0) &&
 554         (try_count % QueuedAllocationWarningCount == 0)) {
 555       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 556     }
 557   }
 558 
 559   ShouldNotReachHere();
 560   return NULL;
 561 }
 562 
 563 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 564                                                    AllocationContext_t context,
 565                                                    uint* gc_count_before_ret,
 566                                                    uint* gclocker_retry_count_ret) {
 567   // Make sure you read the note in attempt_allocation_humongous().
 568 
 569   assert_heap_not_locked_and_not_at_safepoint();
 570   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 571          "be called for humongous allocation requests");
 572 
 573   // We should only get here after the first-level allocation attempt
 574   // (attempt_allocation()) failed to allocate.
 575 
 576   // We will loop until a) we manage to successfully perform the
 577   // allocation or b) we successfully schedule a collection which
 578   // fails to perform the allocation. b) is the only case when we'll
 579   // return NULL.
 580   HeapWord* result = NULL;
 581   for (int try_count = 1; /* we'll return */; try_count += 1) {
 582     bool should_try_gc;
 583     uint gc_count_before;
 584 
 585     {
 586       MutexLockerEx x(Heap_lock);
 587       result = _allocator->attempt_allocation_locked(word_size, context);
 588       if (result != NULL) {
 589         return result;
 590       }
 591 
 592       if (GC_locker::is_active_and_needs_gc()) {
 593         if (g1_policy()->can_expand_young_list()) {
 594           // No need for an ergo verbose message here,
 595           // can_expand_young_list() does this when it returns true.
 596           result = _allocator->attempt_allocation_force(word_size, context);
 597           if (result != NULL) {
 598             return result;
 599           }
 600         }
 601         should_try_gc = false;
 602       } else {
 603         // The GCLocker may not be active but the GCLocker initiated
 604         // GC may not yet have been performed (GCLocker::needs_gc()
 605         // returns true). In this case we do not try this GC and
 606         // wait until the GCLocker initiated GC is performed, and
 607         // then retry the allocation.
 608         if (GC_locker::needs_gc()) {
 609           should_try_gc = false;
 610         } else {
 611           // Read the GC count while still holding the Heap_lock.
 612           gc_count_before = total_collections();
 613           should_try_gc = true;
 614         }
 615       }
 616     }
 617 
 618     if (should_try_gc) {
 619       bool succeeded;
 620       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 621                                    GCCause::_g1_inc_collection_pause);
 622       if (result != NULL) {
 623         assert(succeeded, "only way to get back a non-NULL result");
 624         return result;
 625       }
 626 
 627       if (succeeded) {
 628         // If we get here we successfully scheduled a collection which
 629         // failed to allocate. No point in trying to allocate
 630         // further. We'll just return NULL.
 631         MutexLockerEx x(Heap_lock);
 632         *gc_count_before_ret = total_collections();
 633         return NULL;
 634       }
 635     } else {
 636       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 637         MutexLockerEx x(Heap_lock);
 638         *gc_count_before_ret = total_collections();
 639         return NULL;
 640       }
 641       // The GCLocker is either active or the GCLocker initiated
 642       // GC has not yet been performed. Stall until it is and
 643       // then retry the allocation.
 644       GC_locker::stall_until_clear();
 645       (*gclocker_retry_count_ret) += 1;
 646     }
 647 
 648     // We can reach here if we were unsuccessful in scheduling a
 649     // collection (because another thread beat us to it) or if we were
 650     // stalled due to the GC locker. In either can we should retry the
 651     // allocation attempt in case another thread successfully
 652     // performed a collection and reclaimed enough space. We do the
 653     // first attempt (without holding the Heap_lock) here and the
 654     // follow-on attempt will be at the start of the next loop
 655     // iteration (after taking the Heap_lock).
 656     result = _allocator->attempt_allocation(word_size, context);
 657     if (result != NULL) {
 658       return result;
 659     }
 660 
 661     // Give a warning if we seem to be looping forever.
 662     if ((QueuedAllocationWarningCount > 0) &&
 663         (try_count % QueuedAllocationWarningCount == 0)) {
 664       warning("G1CollectedHeap::attempt_allocation_slow() "
 665               "retries %d times", try_count);
 666     }
 667   }
 668 
 669   ShouldNotReachHere();
 670   return NULL;
 671 }
 672 
 673 void G1CollectedHeap::begin_archive_alloc_range() {
 674   assert_at_safepoint(true /* should_be_vm_thread */);
 675   if (_archive_allocator == NULL) {
 676     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 677   }
 678 }
 679 
 680 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 681   // Allocations in archive regions cannot be of a size that would be considered
 682   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 683   // may be different at archive-restore time.
 684   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 685 }
 686 
 687 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 688   assert_at_safepoint(true /* should_be_vm_thread */);
 689   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 690   if (is_archive_alloc_too_large(word_size)) {
 691     return NULL;
 692   }
 693   return _archive_allocator->archive_mem_allocate(word_size);
 694 }
 695 
 696 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 697                                               size_t end_alignment_in_bytes) {
 698   assert_at_safepoint(true /* should_be_vm_thread */);
 699   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 700 
 701   // Call complete_archive to do the real work, filling in the MemRegion
 702   // array with the archive regions.
 703   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 704   delete _archive_allocator;
 705   _archive_allocator = NULL;
 706 }
 707 
 708 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 709   assert(ranges != NULL, "MemRegion array NULL");
 710   assert(count != 0, "No MemRegions provided");
 711   MemRegion reserved = _hrm.reserved();
 712   for (size_t i = 0; i < count; i++) {
 713     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 714       return false;
 715     }
 716   }
 717   return true;
 718 }
 719 
 720 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 721   assert(!is_init_completed(), "Expect to be called at JVM init time");
 722   assert(ranges != NULL, "MemRegion array NULL");
 723   assert(count != 0, "No MemRegions provided");
 724   MutexLockerEx x(Heap_lock);
 725 
 726   MemRegion reserved = _hrm.reserved();
 727   HeapWord* prev_last_addr = NULL;
 728   HeapRegion* prev_last_region = NULL;
 729 
 730   // Temporarily disable pretouching of heap pages. This interface is used
 731   // when mmap'ing archived heap data in, so pre-touching is wasted.
 732   FlagSetting fs(AlwaysPreTouch, false);
 733 
 734   // Enable archive object checking in G1MarkSweep. We have to let it know
 735   // about each archive range, so that objects in those ranges aren't marked.
 736   G1MarkSweep::enable_archive_object_check();
 737 
 738   // For each specified MemRegion range, allocate the corresponding G1
 739   // regions and mark them as archive regions. We expect the ranges in
 740   // ascending starting address order, without overlap.
 741   for (size_t i = 0; i < count; i++) {
 742     MemRegion curr_range = ranges[i];
 743     HeapWord* start_address = curr_range.start();
 744     size_t word_size = curr_range.word_size();
 745     HeapWord* last_address = curr_range.last();
 746     size_t commits = 0;
 747 
 748     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 749               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 750               p2i(start_address), p2i(last_address));
 751     guarantee(start_address > prev_last_addr,
 752               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 753               p2i(start_address), p2i(prev_last_addr));
 754     prev_last_addr = last_address;
 755 
 756     // Check for ranges that start in the same G1 region in which the previous
 757     // range ended, and adjust the start address so we don't try to allocate
 758     // the same region again. If the current range is entirely within that
 759     // region, skip it, just adjusting the recorded top.
 760     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 761     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 762       start_address = start_region->end();
 763       if (start_address > last_address) {
 764         increase_used(word_size * HeapWordSize);
 765         start_region->set_top(last_address + 1);
 766         continue;
 767       }
 768       start_region->set_top(start_address);
 769       curr_range = MemRegion(start_address, last_address + 1);
 770       start_region = _hrm.addr_to_region(start_address);
 771     }
 772 
 773     // Perform the actual region allocation, exiting if it fails.
 774     // Then note how much new space we have allocated.
 775     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 776       return false;
 777     }
 778     increase_used(word_size * HeapWordSize);
 779     if (commits != 0) {
 780       ergo_verbose1(ErgoHeapSizing,
 781                     "attempt heap expansion",
 782                     ergo_format_reason("allocate archive regions")
 783                     ergo_format_byte("total size"),
 784                     HeapRegion::GrainWords * HeapWordSize * commits);
 785     }
 786 
 787     // Mark each G1 region touched by the range as archive, add it to the old set,
 788     // and set the allocation context and top.
 789     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 790     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 791     prev_last_region = last_region;
 792 
 793     while (curr_region != NULL) {
 794       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 795              "Region already in use (index %u)", curr_region->hrm_index());
 796       _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
 797       curr_region->set_allocation_context(AllocationContext::system());
 798       curr_region->set_archive();
 799       _old_set.add(curr_region);
 800       if (curr_region != last_region) {
 801         curr_region->set_top(curr_region->end());
 802         curr_region = _hrm.next_region_in_heap(curr_region);
 803       } else {
 804         curr_region->set_top(last_address + 1);
 805         curr_region = NULL;
 806       }
 807     }
 808 
 809     // Notify mark-sweep of the archive range.
 810     G1MarkSweep::set_range_archive(curr_range, true);
 811   }
 812   return true;
 813 }
 814 
 815 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 816   assert(!is_init_completed(), "Expect to be called at JVM init time");
 817   assert(ranges != NULL, "MemRegion array NULL");
 818   assert(count != 0, "No MemRegions provided");
 819   MemRegion reserved = _hrm.reserved();
 820   HeapWord *prev_last_addr = NULL;
 821   HeapRegion* prev_last_region = NULL;
 822 
 823   // For each MemRegion, create filler objects, if needed, in the G1 regions
 824   // that contain the address range. The address range actually within the
 825   // MemRegion will not be modified. That is assumed to have been initialized
 826   // elsewhere, probably via an mmap of archived heap data.
 827   MutexLockerEx x(Heap_lock);
 828   for (size_t i = 0; i < count; i++) {
 829     HeapWord* start_address = ranges[i].start();
 830     HeapWord* last_address = ranges[i].last();
 831 
 832     assert(reserved.contains(start_address) && reserved.contains(last_address),
 833            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 834            p2i(start_address), p2i(last_address));
 835     assert(start_address > prev_last_addr,
 836            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 837            p2i(start_address), p2i(prev_last_addr));
 838 
 839     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 840     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 841     HeapWord* bottom_address = start_region->bottom();
 842 
 843     // Check for a range beginning in the same region in which the
 844     // previous one ended.
 845     if (start_region == prev_last_region) {
 846       bottom_address = prev_last_addr + 1;
 847     }
 848 
 849     // Verify that the regions were all marked as archive regions by
 850     // alloc_archive_regions.
 851     HeapRegion* curr_region = start_region;
 852     while (curr_region != NULL) {
 853       guarantee(curr_region->is_archive(),
 854                 "Expected archive region at index %u", curr_region->hrm_index());
 855       if (curr_region != last_region) {
 856         curr_region = _hrm.next_region_in_heap(curr_region);
 857       } else {
 858         curr_region = NULL;
 859       }
 860     }
 861 
 862     prev_last_addr = last_address;
 863     prev_last_region = last_region;
 864 
 865     // Fill the memory below the allocated range with dummy object(s),
 866     // if the region bottom does not match the range start, or if the previous
 867     // range ended within the same G1 region, and there is a gap.
 868     if (start_address != bottom_address) {
 869       size_t fill_size = pointer_delta(start_address, bottom_address);
 870       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 871       increase_used(fill_size * HeapWordSize);
 872     }
 873   }
 874 }
 875 
 876 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 877                                                      uint* gc_count_before_ret,
 878                                                      uint* gclocker_retry_count_ret) {
 879   assert_heap_not_locked_and_not_at_safepoint();
 880   assert(!is_humongous(word_size), "attempt_allocation() should not "
 881          "be called for humongous allocation requests");
 882 
 883   AllocationContext_t context = AllocationContext::current();
 884   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 885 
 886   if (result == NULL) {
 887     result = attempt_allocation_slow(word_size,
 888                                      context,
 889                                      gc_count_before_ret,
 890                                      gclocker_retry_count_ret);
 891   }
 892   assert_heap_not_locked();
 893   if (result != NULL) {
 894     dirty_young_block(result, word_size);
 895   }
 896   return result;
 897 }
 898 
 899 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 900   assert(!is_init_completed(), "Expect to be called at JVM init time");
 901   assert(ranges != NULL, "MemRegion array NULL");
 902   assert(count != 0, "No MemRegions provided");
 903   MemRegion reserved = _hrm.reserved();
 904   HeapWord* prev_last_addr = NULL;
 905   HeapRegion* prev_last_region = NULL;
 906   size_t size_used = 0;
 907   size_t uncommitted_regions = 0;
 908 
 909   // For each Memregion, free the G1 regions that constitute it, and
 910   // notify mark-sweep that the range is no longer to be considered 'archive.'
 911   MutexLockerEx x(Heap_lock);
 912   for (size_t i = 0; i < count; i++) {
 913     HeapWord* start_address = ranges[i].start();
 914     HeapWord* last_address = ranges[i].last();
 915 
 916     assert(reserved.contains(start_address) && reserved.contains(last_address),
 917            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 918            p2i(start_address), p2i(last_address));
 919     assert(start_address > prev_last_addr,
 920            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 921            p2i(start_address), p2i(prev_last_addr));
 922     size_used += ranges[i].byte_size();
 923     prev_last_addr = last_address;
 924 
 925     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 926     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 927 
 928     // Check for ranges that start in the same G1 region in which the previous
 929     // range ended, and adjust the start address so we don't try to free
 930     // the same region again. If the current range is entirely within that
 931     // region, skip it.
 932     if (start_region == prev_last_region) {
 933       start_address = start_region->end();
 934       if (start_address > last_address) {
 935         continue;
 936       }
 937       start_region = _hrm.addr_to_region(start_address);
 938     }
 939     prev_last_region = last_region;
 940 
 941     // After verifying that each region was marked as an archive region by
 942     // alloc_archive_regions, set it free and empty and uncommit it.
 943     HeapRegion* curr_region = start_region;
 944     while (curr_region != NULL) {
 945       guarantee(curr_region->is_archive(),
 946                 "Expected archive region at index %u", curr_region->hrm_index());
 947       uint curr_index = curr_region->hrm_index();
 948       _old_set.remove(curr_region);
 949       curr_region->set_free();
 950       curr_region->set_top(curr_region->bottom());
 951       if (curr_region != last_region) {
 952         curr_region = _hrm.next_region_in_heap(curr_region);
 953       } else {
 954         curr_region = NULL;
 955       }
 956       _hrm.shrink_at(curr_index, 1);
 957       uncommitted_regions++;
 958     }
 959 
 960     // Notify mark-sweep that this is no longer an archive range.
 961     G1MarkSweep::set_range_archive(ranges[i], false);
 962   }
 963 
 964   if (uncommitted_regions != 0) {
 965     ergo_verbose1(ErgoHeapSizing,
 966                   "attempt heap shrinking",
 967                   ergo_format_reason("uncommitted archive regions")
 968                   ergo_format_byte("total size"),
 969                   HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 970   }
 971   decrease_used(size_used);
 972 }
 973 
 974 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 975                                                         uint* gc_count_before_ret,
 976                                                         uint* gclocker_retry_count_ret) {
 977   // The structure of this method has a lot of similarities to
 978   // attempt_allocation_slow(). The reason these two were not merged
 979   // into a single one is that such a method would require several "if
 980   // allocation is not humongous do this, otherwise do that"
 981   // conditional paths which would obscure its flow. In fact, an early
 982   // version of this code did use a unified method which was harder to
 983   // follow and, as a result, it had subtle bugs that were hard to
 984   // track down. So keeping these two methods separate allows each to
 985   // be more readable. It will be good to keep these two in sync as
 986   // much as possible.
 987 
 988   assert_heap_not_locked_and_not_at_safepoint();
 989   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 990          "should only be called for humongous allocations");
 991 
 992   // Humongous objects can exhaust the heap quickly, so we should check if we
 993   // need to start a marking cycle at each humongous object allocation. We do
 994   // the check before we do the actual allocation. The reason for doing it
 995   // before the allocation is that we avoid having to keep track of the newly
 996   // allocated memory while we do a GC.
 997   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 998                                            word_size)) {
 999     collect(GCCause::_g1_humongous_allocation);
1000   }
1001 
1002   // We will loop until a) we manage to successfully perform the
1003   // allocation or b) we successfully schedule a collection which
1004   // fails to perform the allocation. b) is the only case when we'll
1005   // return NULL.
1006   HeapWord* result = NULL;
1007   for (int try_count = 1; /* we'll return */; try_count += 1) {
1008     bool should_try_gc;
1009     uint gc_count_before;
1010 
1011     {
1012       MutexLockerEx x(Heap_lock);
1013 
1014       // Given that humongous objects are not allocated in young
1015       // regions, we'll first try to do the allocation without doing a
1016       // collection hoping that there's enough space in the heap.
1017       result = humongous_obj_allocate(word_size, AllocationContext::current());
1018       if (result != NULL) {
1019         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1020         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1021         return result;
1022       }
1023 
1024       if (GC_locker::is_active_and_needs_gc()) {
1025         should_try_gc = false;
1026       } else {
1027          // The GCLocker may not be active but the GCLocker initiated
1028         // GC may not yet have been performed (GCLocker::needs_gc()
1029         // returns true). In this case we do not try this GC and
1030         // wait until the GCLocker initiated GC is performed, and
1031         // then retry the allocation.
1032         if (GC_locker::needs_gc()) {
1033           should_try_gc = false;
1034         } else {
1035           // Read the GC count while still holding the Heap_lock.
1036           gc_count_before = total_collections();
1037           should_try_gc = true;
1038         }
1039       }
1040     }
1041 
1042     if (should_try_gc) {
1043       // If we failed to allocate the humongous object, we should try to
1044       // do a collection pause (if we're allowed) in case it reclaims
1045       // enough space for the allocation to succeed after the pause.
1046 
1047       bool succeeded;
1048       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1049                                    GCCause::_g1_humongous_allocation);
1050       if (result != NULL) {
1051         assert(succeeded, "only way to get back a non-NULL result");
1052         return result;
1053       }
1054 
1055       if (succeeded) {
1056         // If we get here we successfully scheduled a collection which
1057         // failed to allocate. No point in trying to allocate
1058         // further. We'll just return NULL.
1059         MutexLockerEx x(Heap_lock);
1060         *gc_count_before_ret = total_collections();
1061         return NULL;
1062       }
1063     } else {
1064       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1065         MutexLockerEx x(Heap_lock);
1066         *gc_count_before_ret = total_collections();
1067         return NULL;
1068       }
1069       // The GCLocker is either active or the GCLocker initiated
1070       // GC has not yet been performed. Stall until it is and
1071       // then retry the allocation.
1072       GC_locker::stall_until_clear();
1073       (*gclocker_retry_count_ret) += 1;
1074     }
1075 
1076     // We can reach here if we were unsuccessful in scheduling a
1077     // collection (because another thread beat us to it) or if we were
1078     // stalled due to the GC locker. In either can we should retry the
1079     // allocation attempt in case another thread successfully
1080     // performed a collection and reclaimed enough space.  Give a
1081     // warning if we seem to be looping forever.
1082 
1083     if ((QueuedAllocationWarningCount > 0) &&
1084         (try_count % QueuedAllocationWarningCount == 0)) {
1085       warning("G1CollectedHeap::attempt_allocation_humongous() "
1086               "retries %d times", try_count);
1087     }
1088   }
1089 
1090   ShouldNotReachHere();
1091   return NULL;
1092 }
1093 
1094 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1095                                                            AllocationContext_t context,
1096                                                            bool expect_null_mutator_alloc_region) {
1097   assert_at_safepoint(true /* should_be_vm_thread */);
1098   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1099          "the current alloc region was unexpectedly found to be non-NULL");
1100 
1101   if (!is_humongous(word_size)) {
1102     return _allocator->attempt_allocation_locked(word_size, context);
1103   } else {
1104     HeapWord* result = humongous_obj_allocate(word_size, context);
1105     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1106       collector_state()->set_initiate_conc_mark_if_possible(true);
1107     }
1108     return result;
1109   }
1110 
1111   ShouldNotReachHere();
1112 }
1113 
1114 class PostMCRemSetClearClosure: public HeapRegionClosure {
1115   G1CollectedHeap* _g1h;
1116   ModRefBarrierSet* _mr_bs;
1117 public:
1118   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1119     _g1h(g1h), _mr_bs(mr_bs) {}
1120 
1121   bool doHeapRegion(HeapRegion* r) {
1122     HeapRegionRemSet* hrrs = r->rem_set();
1123 
1124     _g1h->reset_gc_time_stamps(r);
1125 
1126     if (r->is_continues_humongous()) {
1127       // We'll assert that the strong code root list and RSet is empty
1128       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1129       assert(hrrs->occupied() == 0, "RSet should be empty");
1130     } else {
1131       hrrs->clear();
1132     }
1133     // You might think here that we could clear just the cards
1134     // corresponding to the used region.  But no: if we leave a dirty card
1135     // in a region we might allocate into, then it would prevent that card
1136     // from being enqueued, and cause it to be missed.
1137     // Re: the performance cost: we shouldn't be doing full GC anyway!
1138     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1139 
1140     return false;
1141   }
1142 };
1143 
1144 void G1CollectedHeap::clear_rsets_post_compaction() {
1145   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1146   heap_region_iterate(&rs_clear);
1147 }
1148 
1149 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1150   G1CollectedHeap*   _g1h;
1151   UpdateRSOopClosure _cl;
1152 public:
1153   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1154     _cl(g1->g1_rem_set(), worker_i),
1155     _g1h(g1)
1156   { }
1157 
1158   bool doHeapRegion(HeapRegion* r) {
1159     if (!r->is_continues_humongous()) {
1160       _cl.set_from(r);
1161       r->oop_iterate(&_cl);
1162     }
1163     return false;
1164   }
1165 };
1166 
1167 class ParRebuildRSTask: public AbstractGangTask {
1168   G1CollectedHeap* _g1;
1169   HeapRegionClaimer _hrclaimer;
1170 
1171 public:
1172   ParRebuildRSTask(G1CollectedHeap* g1) :
1173       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1174 
1175   void work(uint worker_id) {
1176     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1177     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1178   }
1179 };
1180 
1181 class PostCompactionPrinterClosure: public HeapRegionClosure {
1182 private:
1183   G1HRPrinter* _hr_printer;
1184 public:
1185   bool doHeapRegion(HeapRegion* hr) {
1186     assert(!hr->is_young(), "not expecting to find young regions");
1187     if (hr->is_free()) {
1188       // We only generate output for non-empty regions.
1189     } else if (hr->is_starts_humongous()) {
1190       _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1191     } else if (hr->is_continues_humongous()) {
1192       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1193     } else if (hr->is_archive()) {
1194       _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1195     } else if (hr->is_old()) {
1196       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1197     } else {
1198       ShouldNotReachHere();
1199     }
1200     return false;
1201   }
1202 
1203   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1204     : _hr_printer(hr_printer) { }
1205 };
1206 
1207 void G1CollectedHeap::print_hrm_post_compaction() {
1208   PostCompactionPrinterClosure cl(hr_printer());
1209   heap_region_iterate(&cl);
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 (GC_locker::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   G1Log::update_level();
1231   print_heap_before_gc();
1232   trace_heap_before_gc(gc_tracer);
1233 
1234   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1235 
1236   verify_region_sets_optional();
1237 
1238   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1239                            collector_policy()->should_clear_all_soft_refs();
1240 
1241   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1242 
1243   {
1244     IsGCActiveMark x;
1245 
1246     // Timing
1247     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1248     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1249 
1250     {
1251       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1252       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1253       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1254 
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       verify_before_gc();
1278 
1279       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 should call this after we retire any currently active alloc
1303       // regions so that all the ALLOC / RETIRE events are generated
1304       // before the start GC event.
1305       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1306 
1307       // We may have added regions to the current incremental collection
1308       // set between the last GC or pause and now. We need to clear the
1309       // incremental collection set and then start rebuilding it afresh
1310       // after this full GC.
1311       abandon_collection_set(g1_policy()->inc_cset_head());
1312       g1_policy()->clear_incremental_cset();
1313       g1_policy()->stop_incremental_cset_building();
1314 
1315       tear_down_region_sets(false /* free_list_only */);
1316       collector_state()->set_gcs_are_young(true);
1317 
1318       // See the comments in g1CollectedHeap.hpp and
1319       // G1CollectedHeap::ref_processing_init() about
1320       // how reference processing currently works in G1.
1321 
1322       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1323       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1324 
1325       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1326       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1327 
1328       ref_processor_stw()->enable_discovery();
1329       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1330 
1331       // Do collection work
1332       {
1333         HandleMark hm;  // Discard invalid handles created during gc
1334         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1335       }
1336 
1337       assert(num_free_regions() == 0, "we should not have added any free regions");
1338       rebuild_region_sets(false /* free_list_only */);
1339 
1340       // Enqueue any discovered reference objects that have
1341       // not been removed from the discovered lists.
1342       ref_processor_stw()->enqueue_discovered_references();
1343 
1344 #if defined(COMPILER2) || INCLUDE_JVMCI
1345       DerivedPointerTable::update_pointers();
1346 #endif
1347 
1348       MemoryService::track_memory_usage();
1349 
1350       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1351       ref_processor_stw()->verify_no_references_recorded();
1352 
1353       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1354       ClassLoaderDataGraph::purge();
1355       MetaspaceAux::verify_metrics();
1356 
1357       // Note: since we've just done a full GC, concurrent
1358       // marking is no longer active. Therefore we need not
1359       // re-enable reference discovery for the CM ref processor.
1360       // That will be done at the start of the next marking cycle.
1361       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1362       ref_processor_cm()->verify_no_references_recorded();
1363 
1364       reset_gc_time_stamp();
1365       // Since everything potentially moved, we will clear all remembered
1366       // sets, and clear all cards.  Later we will rebuild remembered
1367       // sets. We will also reset the GC time stamps of the regions.
1368       clear_rsets_post_compaction();
1369       check_gc_time_stamps();
1370 
1371       resize_if_necessary_after_full_collection();
1372 
1373       if (_hr_printer.is_active()) {
1374         // We should do this after we potentially resize the heap so
1375         // that all the COMMIT / UNCOMMIT events are generated before
1376         // the end GC event.
1377 
1378         print_hrm_post_compaction();
1379         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1380       }
1381 
1382       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1383       if (hot_card_cache->use_cache()) {
1384         hot_card_cache->reset_card_counts();
1385         hot_card_cache->reset_hot_cache();
1386       }
1387 
1388       // Rebuild remembered sets of all regions.
1389       uint n_workers =
1390         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1391                                                 workers()->active_workers(),
1392                                                 Threads::number_of_non_daemon_threads());
1393       workers()->set_active_workers(n_workers);
1394 
1395       ParRebuildRSTask rebuild_rs_task(this);
1396       workers()->run_task(&rebuild_rs_task);
1397 
1398       // Rebuild the strong code root lists for each region
1399       rebuild_strong_code_roots();
1400 
1401       if (true) { // FIXME
1402         MetaspaceGC::compute_new_size();
1403       }
1404 
1405 #ifdef TRACESPINNING
1406       ParallelTaskTerminator::print_termination_counts();
1407 #endif
1408 
1409       // Discard all rset updates
1410       JavaThread::dirty_card_queue_set().abandon_logs();
1411       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1412 
1413       _young_list->reset_sampled_info();
1414       // At this point there should be no regions in the
1415       // entire heap tagged as young.
1416       assert(check_young_list_empty(true /* check_heap */),
1417              "young list should be empty at this point");
1418 
1419       // Update the number of full collections that have been completed.
1420       increment_old_marking_cycles_completed(false /* concurrent */);
1421 
1422       _hrm.verify_optional();
1423       verify_region_sets_optional();
1424 
1425       verify_after_gc();
1426 
1427       // Clear the previous marking bitmap, if needed for bitmap verification.
1428       // Note we cannot do this when we clear the next marking bitmap in
1429       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1430       // objects marked during a full GC against the previous bitmap.
1431       // But we need to clear it before calling check_bitmaps below since
1432       // the full GC has compacted objects and updated TAMS but not updated
1433       // the prev bitmap.
1434       if (G1VerifyBitmaps) {
1435         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1436       }
1437       check_bitmaps("Full GC End");
1438 
1439       // Start a new incremental collection set for the next pause
1440       assert(g1_policy()->collection_set() == NULL, "must be");
1441       g1_policy()->start_incremental_cset_building();
1442 
1443       clear_cset_fast_test();
1444 
1445       _allocator->init_mutator_alloc_region();
1446 
1447       g1_policy()->record_full_collection_end();
1448 
1449       if (G1Log::fine()) {
1450         g1_policy()->print_heap_transition();
1451       }
1452 
1453       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1454       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1455       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1456       // before any GC notifications are raised.
1457       g1mm()->update_sizes();
1458 
1459       gc_epilogue(true);
1460     }
1461 
1462     if (G1Log::finer()) {
1463       g1_policy()->print_detailed_heap_transition(true /* full */);
1464     }
1465 
1466     print_heap_after_gc();
1467     trace_heap_after_gc(gc_tracer);
1468 
1469     post_full_gc_dump(gc_timer);
1470 
1471     gc_timer->register_gc_end();
1472     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1473   }
1474 
1475   return true;
1476 }
1477 
1478 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1479   // Currently, there is no facility in the do_full_collection(bool) API to notify
1480   // the caller that the collection did not succeed (e.g., because it was locked
1481   // out by the GC locker). So, right now, we'll ignore the return value.
1482   bool dummy = do_full_collection(true,                /* explicit_gc */
1483                                   clear_all_soft_refs);
1484 }
1485 
1486 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1487   // Include bytes that will be pre-allocated to support collections, as "used".
1488   const size_t used_after_gc = used();
1489   const size_t capacity_after_gc = capacity();
1490   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1491 
1492   // This is enforced in arguments.cpp.
1493   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1494          "otherwise the code below doesn't make sense");
1495 
1496   // We don't have floating point command-line arguments
1497   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1498   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1499   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1500   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1501 
1502   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1503   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1504 
1505   // We have to be careful here as these two calculations can overflow
1506   // 32-bit size_t's.
1507   double used_after_gc_d = (double) used_after_gc;
1508   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1509   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1510 
1511   // Let's make sure that they are both under the max heap size, which
1512   // by default will make them fit into a size_t.
1513   double desired_capacity_upper_bound = (double) max_heap_size;
1514   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1515                                     desired_capacity_upper_bound);
1516   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1517                                     desired_capacity_upper_bound);
1518 
1519   // We can now safely turn them into size_t's.
1520   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1521   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1522 
1523   // This assert only makes sense here, before we adjust them
1524   // with respect to the min and max heap size.
1525   assert(minimum_desired_capacity <= maximum_desired_capacity,
1526          "minimum_desired_capacity = " SIZE_FORMAT ", "
1527          "maximum_desired_capacity = " SIZE_FORMAT,
1528          minimum_desired_capacity, maximum_desired_capacity);
1529 
1530   // Should not be greater than the heap max size. No need to adjust
1531   // it with respect to the heap min size as it's a lower bound (i.e.,
1532   // we'll try to make the capacity larger than it, not smaller).
1533   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1534   // Should not be less than the heap min size. No need to adjust it
1535   // with respect to the heap max size as it's an upper bound (i.e.,
1536   // we'll try to make the capacity smaller than it, not greater).
1537   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1538 
1539   if (capacity_after_gc < minimum_desired_capacity) {
1540     // Don't expand unless it's significant
1541     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1542     ergo_verbose4(ErgoHeapSizing,
1543                   "attempt heap expansion",
1544                   ergo_format_reason("capacity lower than "
1545                                      "min desired capacity after Full GC")
1546                   ergo_format_byte("capacity")
1547                   ergo_format_byte("occupancy")
1548                   ergo_format_byte_perc("min desired capacity"),
1549                   capacity_after_gc, used_after_gc,
1550                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1551     expand(expand_bytes);
1552 
1553     // No expansion, now see if we want to shrink
1554   } else if (capacity_after_gc > maximum_desired_capacity) {
1555     // Capacity too large, compute shrinking size
1556     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1557     ergo_verbose4(ErgoHeapSizing,
1558                   "attempt heap shrinking",
1559                   ergo_format_reason("capacity higher than "
1560                                      "max desired capacity after Full GC")
1561                   ergo_format_byte("capacity")
1562                   ergo_format_byte("occupancy")
1563                   ergo_format_byte_perc("max desired capacity"),
1564                   capacity_after_gc, used_after_gc,
1565                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1566     shrink(shrink_bytes);
1567   }
1568 }
1569 
1570 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1571                                                             AllocationContext_t context,
1572                                                             bool do_gc,
1573                                                             bool clear_all_soft_refs,
1574                                                             bool expect_null_mutator_alloc_region,
1575                                                             bool* gc_succeeded) {
1576   *gc_succeeded = true;
1577   // Let's attempt the allocation first.
1578   HeapWord* result =
1579     attempt_allocation_at_safepoint(word_size,
1580                                     context,
1581                                     expect_null_mutator_alloc_region);
1582   if (result != NULL) {
1583     assert(*gc_succeeded, "sanity");
1584     return result;
1585   }
1586 
1587   // In a G1 heap, we're supposed to keep allocation from failing by
1588   // incremental pauses.  Therefore, at least for now, we'll favor
1589   // expansion over collection.  (This might change in the future if we can
1590   // do something smarter than full collection to satisfy a failed alloc.)
1591   result = expand_and_allocate(word_size, context);
1592   if (result != NULL) {
1593     assert(*gc_succeeded, "sanity");
1594     return result;
1595   }
1596 
1597   if (do_gc) {
1598     // Expansion didn't work, we'll try to do a Full GC.
1599     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1600                                        clear_all_soft_refs);
1601   }
1602 
1603   return NULL;
1604 }
1605 
1606 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1607                                                      AllocationContext_t context,
1608                                                      bool* succeeded) {
1609   assert_at_safepoint(true /* should_be_vm_thread */);
1610 
1611   // Attempts to allocate followed by Full GC.
1612   HeapWord* result =
1613     satisfy_failed_allocation_helper(word_size,
1614                                      context,
1615                                      true,  /* do_gc */
1616                                      false, /* clear_all_soft_refs */
1617                                      false, /* expect_null_mutator_alloc_region */
1618                                      succeeded);
1619 
1620   if (result != NULL || !*succeeded) {
1621     return result;
1622   }
1623 
1624   // Attempts to allocate followed by Full GC that will collect all soft references.
1625   result = satisfy_failed_allocation_helper(word_size,
1626                                             context,
1627                                             true, /* do_gc */
1628                                             true, /* clear_all_soft_refs */
1629                                             true, /* expect_null_mutator_alloc_region */
1630                                             succeeded);
1631 
1632   if (result != NULL || !*succeeded) {
1633     return result;
1634   }
1635 
1636   // Attempts to allocate, no GC
1637   result = satisfy_failed_allocation_helper(word_size,
1638                                             context,
1639                                             false, /* do_gc */
1640                                             false, /* clear_all_soft_refs */
1641                                             true,  /* expect_null_mutator_alloc_region */
1642                                             succeeded);
1643 
1644   if (result != NULL) {
1645     assert(*succeeded, "sanity");
1646     return result;
1647   }
1648 
1649   assert(!collector_policy()->should_clear_all_soft_refs(),
1650          "Flag should have been handled and cleared prior to this point");
1651 
1652   // What else?  We might try synchronous finalization later.  If the total
1653   // space available is large enough for the allocation, then a more
1654   // complete compaction phase than we've tried so far might be
1655   // appropriate.
1656   assert(*succeeded, "sanity");
1657   return NULL;
1658 }
1659 
1660 // Attempting to expand the heap sufficiently
1661 // to support an allocation of the given "word_size".  If
1662 // successful, perform the allocation and return the address of the
1663 // allocated block, or else "NULL".
1664 
1665 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1666   assert_at_safepoint(true /* should_be_vm_thread */);
1667 
1668   verify_region_sets_optional();
1669 
1670   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1671   ergo_verbose1(ErgoHeapSizing,
1672                 "attempt heap expansion",
1673                 ergo_format_reason("allocation request failed")
1674                 ergo_format_byte("allocation request"),
1675                 word_size * HeapWordSize);
1676   if (expand(expand_bytes)) {
1677     _hrm.verify_optional();
1678     verify_region_sets_optional();
1679     return attempt_allocation_at_safepoint(word_size,
1680                                            context,
1681                                            false /* expect_null_mutator_alloc_region */);
1682   }
1683   return NULL;
1684 }
1685 
1686 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1687   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1688   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1689                                        HeapRegion::GrainBytes);
1690   ergo_verbose2(ErgoHeapSizing,
1691                 "expand the heap",
1692                 ergo_format_byte("requested expansion amount")
1693                 ergo_format_byte("attempted expansion amount"),
1694                 expand_bytes, aligned_expand_bytes);
1695 
1696   if (is_maximal_no_gc()) {
1697     ergo_verbose0(ErgoHeapSizing,
1698                       "did not expand the heap",
1699                       ergo_format_reason("heap already fully expanded"));
1700     return false;
1701   }
1702 
1703   double expand_heap_start_time_sec = os::elapsedTime();
1704   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1705   assert(regions_to_expand > 0, "Must expand by at least one region");
1706 
1707   uint expanded_by = _hrm.expand_by(regions_to_expand);
1708   if (expand_time_ms != NULL) {
1709     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1710   }
1711 
1712   if (expanded_by > 0) {
1713     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1714     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1715     g1_policy()->record_new_heap_size(num_regions());
1716   } else {
1717     ergo_verbose0(ErgoHeapSizing,
1718                   "did not expand the heap",
1719                   ergo_format_reason("heap expansion operation failed"));
1720     // The expansion of the virtual storage space was unsuccessful.
1721     // Let's see if it was because we ran out of swap.
1722     if (G1ExitOnExpansionFailure &&
1723         _hrm.available() >= regions_to_expand) {
1724       // We had head room...
1725       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1726     }
1727   }
1728   return regions_to_expand > 0;
1729 }
1730 
1731 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1732   size_t aligned_shrink_bytes =
1733     ReservedSpace::page_align_size_down(shrink_bytes);
1734   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1735                                          HeapRegion::GrainBytes);
1736   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1737 
1738   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1739   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1740 
1741   ergo_verbose3(ErgoHeapSizing,
1742                 "shrink the heap",
1743                 ergo_format_byte("requested shrinking amount")
1744                 ergo_format_byte("aligned shrinking amount")
1745                 ergo_format_byte("attempted shrinking amount"),
1746                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1747   if (num_regions_removed > 0) {
1748     g1_policy()->record_new_heap_size(num_regions());
1749   } else {
1750     ergo_verbose0(ErgoHeapSizing,
1751                   "did not shrink the heap",
1752                   ergo_format_reason("heap shrinking operation failed"));
1753   }
1754 }
1755 
1756 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1757   verify_region_sets_optional();
1758 
1759   // We should only reach here at the end of a Full GC which means we
1760   // should not not be holding to any GC alloc regions. The method
1761   // below will make sure of that and do any remaining clean up.
1762   _allocator->abandon_gc_alloc_regions();
1763 
1764   // Instead of tearing down / rebuilding the free lists here, we
1765   // could instead use the remove_all_pending() method on free_list to
1766   // remove only the ones that we need to remove.
1767   tear_down_region_sets(true /* free_list_only */);
1768   shrink_helper(shrink_bytes);
1769   rebuild_region_sets(true /* free_list_only */);
1770 
1771   _hrm.verify_optional();
1772   verify_region_sets_optional();
1773 }
1774 
1775 // Public methods.
1776 
1777 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1778   CollectedHeap(),
1779   _g1_policy(policy_),
1780   _dirty_card_queue_set(false),
1781   _is_alive_closure_cm(this),
1782   _is_alive_closure_stw(this),
1783   _ref_processor_cm(NULL),
1784   _ref_processor_stw(NULL),
1785   _bot_shared(NULL),
1786   _cg1r(NULL),
1787   _g1mm(NULL),
1788   _refine_cte_cl(NULL),
1789   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1790   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1791   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1792   _humongous_reclaim_candidates(),
1793   _has_humongous_reclaim_candidates(false),
1794   _archive_allocator(NULL),
1795   _free_regions_coming(false),
1796   _young_list(new YoungList(this)),
1797   _gc_time_stamp(0),
1798   _summary_bytes_used(0),
1799   _survivor_evac_stats(YoungPLABSize, PLABWeight),
1800   _old_evac_stats(OldPLABSize, PLABWeight),
1801   _expand_heap_after_alloc_failure(true),
1802   _old_marking_cycles_started(0),
1803   _old_marking_cycles_completed(0),
1804   _heap_summary_sent(false),
1805   _in_cset_fast_test(),
1806   _dirty_cards_region_list(NULL),
1807   _worker_cset_start_region(NULL),
1808   _worker_cset_start_region_time_stamp(NULL),
1809   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1810   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1811   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1812   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1813 
1814   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1815                           /* are_GC_task_threads */true,
1816                           /* are_ConcurrentGC_threads */false);
1817   _workers->initialize_workers();
1818 
1819   _allocator = G1Allocator::create_allocator(this);
1820   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1821 
1822   // Override the default _filler_array_max_size so that no humongous filler
1823   // objects are created.
1824   _filler_array_max_size = _humongous_object_threshold_in_words;
1825 
1826   uint n_queues = ParallelGCThreads;
1827   _task_queues = new RefToScanQueueSet(n_queues);
1828 
1829   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1830   assert(n_rem_sets > 0, "Invariant.");
1831 
1832   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1833   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1834   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1835 
1836   for (uint i = 0; i < n_queues; i++) {
1837     RefToScanQueue* q = new RefToScanQueue();
1838     q->initialize();
1839     _task_queues->register_queue(i, q);
1840     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1841   }
1842   clear_cset_start_regions();
1843 
1844   // Initialize the G1EvacuationFailureALot counters and flags.
1845   NOT_PRODUCT(reset_evacuation_should_fail();)
1846 
1847   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1848 }
1849 
1850 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1851                                                                  size_t size,
1852                                                                  size_t translation_factor) {
1853   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1854   // Allocate a new reserved space, preferring to use large pages.
1855   ReservedSpace rs(size, preferred_page_size);
1856   G1RegionToSpaceMapper* result  =
1857     G1RegionToSpaceMapper::create_mapper(rs,
1858                                          size,
1859                                          rs.alignment(),
1860                                          HeapRegion::GrainBytes,
1861                                          translation_factor,
1862                                          mtGC);
1863   if (TracePageSizes) {
1864     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1865                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1866   }
1867   return result;
1868 }
1869 
1870 jint G1CollectedHeap::initialize() {
1871   CollectedHeap::pre_initialize();
1872   os::enable_vtime();
1873 
1874   G1Log::init();
1875 
1876   // Necessary to satisfy locking discipline assertions.
1877 
1878   MutexLocker x(Heap_lock);
1879 
1880   // We have to initialize the printer before committing the heap, as
1881   // it will be used then.
1882   _hr_printer.set_active(G1PrintHeapRegions);
1883 
1884   // While there are no constraints in the GC code that HeapWordSize
1885   // be any particular value, there are multiple other areas in the
1886   // system which believe this to be true (e.g. oop->object_size in some
1887   // cases incorrectly returns the size in wordSize units rather than
1888   // HeapWordSize).
1889   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1890 
1891   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1892   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1893   size_t heap_alignment = collector_policy()->heap_alignment();
1894 
1895   // Ensure that the sizes are properly aligned.
1896   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1897   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1898   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1899 
1900   _refine_cte_cl = new RefineCardTableEntryClosure();
1901 
1902   jint ecode = JNI_OK;
1903   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1904   if (_cg1r == NULL) {
1905     return ecode;
1906   }
1907 
1908   // Reserve the maximum.
1909 
1910   // When compressed oops are enabled, the preferred heap base
1911   // is calculated by subtracting the requested size from the
1912   // 32Gb boundary and using the result as the base address for
1913   // heap reservation. If the requested size is not aligned to
1914   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1915   // into the ReservedHeapSpace constructor) then the actual
1916   // base of the reserved heap may end up differing from the
1917   // address that was requested (i.e. the preferred heap base).
1918   // If this happens then we could end up using a non-optimal
1919   // compressed oops mode.
1920 
1921   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1922                                                  heap_alignment);
1923 
1924   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1925 
1926   // Create the barrier set for the entire reserved region.
1927   G1SATBCardTableLoggingModRefBS* bs
1928     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1929   bs->initialize();
1930   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1931   set_barrier_set(bs);
1932 
1933   // Also create a G1 rem set.
1934   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1935 
1936   // Carve out the G1 part of the heap.
1937 
1938   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1939   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1940   G1RegionToSpaceMapper* heap_storage =
1941     G1RegionToSpaceMapper::create_mapper(g1_rs,
1942                                          g1_rs.size(),
1943                                          page_size,
1944                                          HeapRegion::GrainBytes,
1945                                          1,
1946                                          mtJavaHeap);
1947   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1948                        max_byte_size, page_size,
1949                        heap_rs.base(),
1950                        heap_rs.size());
1951   heap_storage->set_mapping_changed_listener(&_listener);
1952 
1953   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1954   G1RegionToSpaceMapper* bot_storage =
1955     create_aux_memory_mapper("Block offset table",
1956                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1957                              G1BlockOffsetSharedArray::heap_map_factor());
1958 
1959   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1960   G1RegionToSpaceMapper* cardtable_storage =
1961     create_aux_memory_mapper("Card table",
1962                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1963                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1964 
1965   G1RegionToSpaceMapper* card_counts_storage =
1966     create_aux_memory_mapper("Card counts table",
1967                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1968                              G1CardCounts::heap_map_factor());
1969 
1970   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1971   G1RegionToSpaceMapper* prev_bitmap_storage =
1972     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1973   G1RegionToSpaceMapper* next_bitmap_storage =
1974     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1975 
1976   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1977   g1_barrier_set()->initialize(cardtable_storage);
1978    // Do later initialization work for concurrent refinement.
1979   _cg1r->init(card_counts_storage);
1980 
1981   // 6843694 - ensure that the maximum region index can fit
1982   // in the remembered set structures.
1983   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1984   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1985 
1986   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1987   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1988   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1989             "too many cards per region");
1990 
1991   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1992 
1993   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1994 
1995   {
1996     HeapWord* start = _hrm.reserved().start();
1997     HeapWord* end = _hrm.reserved().end();
1998     size_t granularity = HeapRegion::GrainBytes;
1999 
2000     _in_cset_fast_test.initialize(start, end, granularity);
2001     _humongous_reclaim_candidates.initialize(start, end, granularity);
2002   }
2003 
2004   // Create the ConcurrentMark data structure and thread.
2005   // (Must do this late, so that "max_regions" is defined.)
2006   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2007   if (_cm == NULL || !_cm->completed_initialization()) {
2008     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2009     return JNI_ENOMEM;
2010   }
2011   _cmThread = _cm->cmThread();
2012 
2013   // Initialize the from_card cache structure of HeapRegionRemSet.
2014   HeapRegionRemSet::init_heap(max_regions());
2015 
2016   // Now expand into the initial heap size.
2017   if (!expand(init_byte_size)) {
2018     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2019     return JNI_ENOMEM;
2020   }
2021 
2022   // Perform any initialization actions delegated to the policy.
2023   g1_policy()->init();
2024 
2025   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2026                                                SATB_Q_FL_lock,
2027                                                G1SATBProcessCompletedThreshold,
2028                                                Shared_SATB_Q_lock);
2029 
2030   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2031                                                 DirtyCardQ_CBL_mon,
2032                                                 DirtyCardQ_FL_lock,
2033                                                 concurrent_g1_refine()->yellow_zone(),
2034                                                 concurrent_g1_refine()->red_zone(),
2035                                                 Shared_DirtyCardQ_lock);
2036 
2037   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2038                                     DirtyCardQ_CBL_mon,
2039                                     DirtyCardQ_FL_lock,
2040                                     -1, // never trigger processing
2041                                     -1, // no limit on length
2042                                     Shared_DirtyCardQ_lock,
2043                                     &JavaThread::dirty_card_queue_set());
2044 
2045   // Here we allocate the dummy HeapRegion that is required by the
2046   // G1AllocRegion class.
2047   HeapRegion* dummy_region = _hrm.get_dummy_region();
2048 
2049   // We'll re-use the same region whether the alloc region will
2050   // require BOT updates or not and, if it doesn't, then a non-young
2051   // region will complain that it cannot support allocations without
2052   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2053   dummy_region->set_eden();
2054   // Make sure it's full.
2055   dummy_region->set_top(dummy_region->end());
2056   G1AllocRegion::setup(this, dummy_region);
2057 
2058   _allocator->init_mutator_alloc_region();
2059 
2060   // Do create of the monitoring and management support so that
2061   // values in the heap have been properly initialized.
2062   _g1mm = new G1MonitoringSupport(this);
2063 
2064   G1StringDedup::initialize();
2065 
2066   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2067   for (uint i = 0; i < ParallelGCThreads; i++) {
2068     new (&_preserved_objs[i]) OopAndMarkOopStack();
2069   }
2070 
2071   return JNI_OK;
2072 }
2073 
2074 void G1CollectedHeap::stop() {
2075   // Stop all concurrent threads. We do this to make sure these threads
2076   // do not continue to execute and access resources (e.g. gclog_or_tty)
2077   // that are destroyed during shutdown.
2078   _cg1r->stop();
2079   _cmThread->stop();
2080   if (G1StringDedup::is_enabled()) {
2081     G1StringDedup::stop();
2082   }
2083 }
2084 
2085 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2086   return HeapRegion::max_region_size();
2087 }
2088 
2089 void G1CollectedHeap::post_initialize() {
2090   CollectedHeap::post_initialize();
2091   ref_processing_init();
2092 }
2093 
2094 void G1CollectedHeap::ref_processing_init() {
2095   // Reference processing in G1 currently works as follows:
2096   //
2097   // * There are two reference processor instances. One is
2098   //   used to record and process discovered references
2099   //   during concurrent marking; the other is used to
2100   //   record and process references during STW pauses
2101   //   (both full and incremental).
2102   // * Both ref processors need to 'span' the entire heap as
2103   //   the regions in the collection set may be dotted around.
2104   //
2105   // * For the concurrent marking ref processor:
2106   //   * Reference discovery is enabled at initial marking.
2107   //   * Reference discovery is disabled and the discovered
2108   //     references processed etc during remarking.
2109   //   * Reference discovery is MT (see below).
2110   //   * Reference discovery requires a barrier (see below).
2111   //   * Reference processing may or may not be MT
2112   //     (depending on the value of ParallelRefProcEnabled
2113   //     and ParallelGCThreads).
2114   //   * A full GC disables reference discovery by the CM
2115   //     ref processor and abandons any entries on it's
2116   //     discovered lists.
2117   //
2118   // * For the STW processor:
2119   //   * Non MT discovery is enabled at the start of a full GC.
2120   //   * Processing and enqueueing during a full GC is non-MT.
2121   //   * During a full GC, references are processed after marking.
2122   //
2123   //   * Discovery (may or may not be MT) is enabled at the start
2124   //     of an incremental evacuation pause.
2125   //   * References are processed near the end of a STW evacuation pause.
2126   //   * For both types of GC:
2127   //     * Discovery is atomic - i.e. not concurrent.
2128   //     * Reference discovery will not need a barrier.
2129 
2130   MemRegion mr = reserved_region();
2131 
2132   // Concurrent Mark ref processor
2133   _ref_processor_cm =
2134     new ReferenceProcessor(mr,    // span
2135                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2136                                 // mt processing
2137                            ParallelGCThreads,
2138                                 // degree of mt processing
2139                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2140                                 // mt discovery
2141                            MAX2(ParallelGCThreads, ConcGCThreads),
2142                                 // degree of mt discovery
2143                            false,
2144                                 // Reference discovery is not atomic
2145                            &_is_alive_closure_cm);
2146                                 // is alive closure
2147                                 // (for efficiency/performance)
2148 
2149   // STW ref processor
2150   _ref_processor_stw =
2151     new ReferenceProcessor(mr,    // span
2152                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2153                                 // mt processing
2154                            ParallelGCThreads,
2155                                 // degree of mt processing
2156                            (ParallelGCThreads > 1),
2157                                 // mt discovery
2158                            ParallelGCThreads,
2159                                 // degree of mt discovery
2160                            true,
2161                                 // Reference discovery is atomic
2162                            &_is_alive_closure_stw);
2163                                 // is alive closure
2164                                 // (for efficiency/performance)
2165 }
2166 
2167 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2168   return g1_policy();
2169 }
2170 
2171 size_t G1CollectedHeap::capacity() const {
2172   return _hrm.length() * HeapRegion::GrainBytes;
2173 }
2174 
2175 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2176   hr->reset_gc_time_stamp();
2177 }
2178 
2179 #ifndef PRODUCT
2180 
2181 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2182 private:
2183   unsigned _gc_time_stamp;
2184   bool _failures;
2185 
2186 public:
2187   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2188     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2189 
2190   virtual bool doHeapRegion(HeapRegion* hr) {
2191     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2192     if (_gc_time_stamp != region_gc_time_stamp) {
2193       gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2194                              "expected %d", HR_FORMAT_PARAMS(hr),
2195                              region_gc_time_stamp, _gc_time_stamp);
2196       _failures = true;
2197     }
2198     return false;
2199   }
2200 
2201   bool failures() { return _failures; }
2202 };
2203 
2204 void G1CollectedHeap::check_gc_time_stamps() {
2205   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2206   heap_region_iterate(&cl);
2207   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2208 }
2209 #endif // PRODUCT
2210 
2211 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2212   _cg1r->hot_card_cache()->drain(cl, worker_i);
2213 }
2214 
2215 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2216   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2217   size_t n_completed_buffers = 0;
2218   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2219     n_completed_buffers++;
2220   }
2221   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2222   dcqs.clear_n_completed_buffers();
2223   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2224 }
2225 
2226 // Computes the sum of the storage used by the various regions.
2227 size_t G1CollectedHeap::used() const {
2228   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2229   if (_archive_allocator != NULL) {
2230     result += _archive_allocator->used();
2231   }
2232   return result;
2233 }
2234 
2235 size_t G1CollectedHeap::used_unlocked() const {
2236   return _summary_bytes_used;
2237 }
2238 
2239 class SumUsedClosure: public HeapRegionClosure {
2240   size_t _used;
2241 public:
2242   SumUsedClosure() : _used(0) {}
2243   bool doHeapRegion(HeapRegion* r) {
2244     _used += r->used();
2245     return false;
2246   }
2247   size_t result() { return _used; }
2248 };
2249 
2250 size_t G1CollectedHeap::recalculate_used() const {
2251   double recalculate_used_start = os::elapsedTime();
2252 
2253   SumUsedClosure blk;
2254   heap_region_iterate(&blk);
2255 
2256   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2257   return blk.result();
2258 }
2259 
2260 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2261   switch (cause) {
2262     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2263     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2264     case GCCause::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2265     case GCCause::_g1_humongous_allocation: return true;
2266     case GCCause::_update_allocation_context_stats_inc: return true;
2267     case GCCause::_wb_conc_mark:            return true;
2268     default:                                return false;
2269   }
2270 }
2271 
2272 #ifndef PRODUCT
2273 void G1CollectedHeap::allocate_dummy_regions() {
2274   // Let's fill up most of the region
2275   size_t word_size = HeapRegion::GrainWords - 1024;
2276   // And as a result the region we'll allocate will be humongous.
2277   guarantee(is_humongous(word_size), "sanity");
2278 
2279   // _filler_array_max_size is set to humongous object threshold
2280   // but temporarily change it to use CollectedHeap::fill_with_object().
2281   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2282 
2283   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2284     // Let's use the existing mechanism for the allocation
2285     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2286                                                  AllocationContext::system());
2287     if (dummy_obj != NULL) {
2288       MemRegion mr(dummy_obj, word_size);
2289       CollectedHeap::fill_with_object(mr);
2290     } else {
2291       // If we can't allocate once, we probably cannot allocate
2292       // again. Let's get out of the loop.
2293       break;
2294     }
2295   }
2296 }
2297 #endif // !PRODUCT
2298 
2299 void G1CollectedHeap::increment_old_marking_cycles_started() {
2300   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2301          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2302          "Wrong marking cycle count (started: %d, completed: %d)",
2303          _old_marking_cycles_started, _old_marking_cycles_completed);
2304 
2305   _old_marking_cycles_started++;
2306 }
2307 
2308 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2309   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2310 
2311   // We assume that if concurrent == true, then the caller is a
2312   // concurrent thread that was joined the Suspendible Thread
2313   // Set. If there's ever a cheap way to check this, we should add an
2314   // assert here.
2315 
2316   // Given that this method is called at the end of a Full GC or of a
2317   // concurrent cycle, and those can be nested (i.e., a Full GC can
2318   // interrupt a concurrent cycle), the number of full collections
2319   // completed should be either one (in the case where there was no
2320   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2321   // behind the number of full collections started.
2322 
2323   // This is the case for the inner caller, i.e. a Full GC.
2324   assert(concurrent ||
2325          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2326          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2327          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2328          "is inconsistent with _old_marking_cycles_completed = %u",
2329          _old_marking_cycles_started, _old_marking_cycles_completed);
2330 
2331   // This is the case for the outer caller, i.e. the concurrent cycle.
2332   assert(!concurrent ||
2333          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2334          "for outer caller (concurrent cycle): "
2335          "_old_marking_cycles_started = %u "
2336          "is inconsistent with _old_marking_cycles_completed = %u",
2337          _old_marking_cycles_started, _old_marking_cycles_completed);
2338 
2339   _old_marking_cycles_completed += 1;
2340 
2341   // We need to clear the "in_progress" flag in the CM thread before
2342   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2343   // is set) so that if a waiter requests another System.gc() it doesn't
2344   // incorrectly see that a marking cycle is still in progress.
2345   if (concurrent) {
2346     _cmThread->set_idle();
2347   }
2348 
2349   // This notify_all() will ensure that a thread that called
2350   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2351   // and it's waiting for a full GC to finish will be woken up. It is
2352   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2353   FullGCCount_lock->notify_all();
2354 }
2355 
2356 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2357   GCIdMarkAndRestore conc_gc_id_mark;
2358   collector_state()->set_concurrent_cycle_started(true);
2359   _gc_timer_cm->register_gc_start(start_time);
2360 
2361   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2362   trace_heap_before_gc(_gc_tracer_cm);
2363   _cmThread->set_gc_id(GCId::current());
2364 }
2365 
2366 void G1CollectedHeap::register_concurrent_cycle_end() {
2367   if (collector_state()->concurrent_cycle_started()) {
2368     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2369     if (_cm->has_aborted()) {
2370       _gc_tracer_cm->report_concurrent_mode_failure();
2371     }
2372 
2373     _gc_timer_cm->register_gc_end();
2374     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2375 
2376     // Clear state variables to prepare for the next concurrent cycle.
2377      collector_state()->set_concurrent_cycle_started(false);
2378     _heap_summary_sent = false;
2379   }
2380 }
2381 
2382 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2383   if (collector_state()->concurrent_cycle_started()) {
2384     // This function can be called when:
2385     //  the cleanup pause is run
2386     //  the concurrent cycle is aborted before the cleanup pause.
2387     //  the concurrent cycle is aborted after the cleanup pause,
2388     //   but before the concurrent cycle end has been registered.
2389     // Make sure that we only send the heap information once.
2390     if (!_heap_summary_sent) {
2391       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2392       trace_heap_after_gc(_gc_tracer_cm);
2393       _heap_summary_sent = true;
2394     }
2395   }
2396 }
2397 
2398 void G1CollectedHeap::collect(GCCause::Cause cause) {
2399   assert_heap_not_locked();
2400 
2401   uint gc_count_before;
2402   uint old_marking_count_before;
2403   uint full_gc_count_before;
2404   bool retry_gc;
2405 
2406   do {
2407     retry_gc = false;
2408 
2409     {
2410       MutexLocker ml(Heap_lock);
2411 
2412       // Read the GC count while holding the Heap_lock
2413       gc_count_before = total_collections();
2414       full_gc_count_before = total_full_collections();
2415       old_marking_count_before = _old_marking_cycles_started;
2416     }
2417 
2418     if (should_do_concurrent_full_gc(cause)) {
2419       // Schedule an initial-mark evacuation pause that will start a
2420       // concurrent cycle. We're setting word_size to 0 which means that
2421       // we are not requesting a post-GC allocation.
2422       VM_G1IncCollectionPause op(gc_count_before,
2423                                  0,     /* word_size */
2424                                  true,  /* should_initiate_conc_mark */
2425                                  g1_policy()->max_pause_time_ms(),
2426                                  cause);
2427       op.set_allocation_context(AllocationContext::current());
2428 
2429       VMThread::execute(&op);
2430       if (!op.pause_succeeded()) {
2431         if (old_marking_count_before == _old_marking_cycles_started) {
2432           retry_gc = op.should_retry_gc();
2433         } else {
2434           // A Full GC happened while we were trying to schedule the
2435           // initial-mark GC. No point in starting a new cycle given
2436           // that the whole heap was collected anyway.
2437         }
2438 
2439         if (retry_gc) {
2440           if (GC_locker::is_active_and_needs_gc()) {
2441             GC_locker::stall_until_clear();
2442           }
2443         }
2444       }
2445     } else {
2446       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2447           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2448 
2449         // Schedule a standard evacuation pause. We're setting word_size
2450         // to 0 which means that we are not requesting a post-GC allocation.
2451         VM_G1IncCollectionPause op(gc_count_before,
2452                                    0,     /* word_size */
2453                                    false, /* should_initiate_conc_mark */
2454                                    g1_policy()->max_pause_time_ms(),
2455                                    cause);
2456         VMThread::execute(&op);
2457       } else {
2458         // Schedule a Full GC.
2459         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2460         VMThread::execute(&op);
2461       }
2462     }
2463   } while (retry_gc);
2464 }
2465 
2466 bool G1CollectedHeap::is_in(const void* p) const {
2467   if (_hrm.reserved().contains(p)) {
2468     // Given that we know that p is in the reserved space,
2469     // heap_region_containing() should successfully
2470     // return the containing region.
2471     HeapRegion* hr = heap_region_containing(p);
2472     return hr->is_in(p);
2473   } else {
2474     return false;
2475   }
2476 }
2477 
2478 #ifdef ASSERT
2479 bool G1CollectedHeap::is_in_exact(const void* p) const {
2480   bool contains = reserved_region().contains(p);
2481   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2482   if (contains && available) {
2483     return true;
2484   } else {
2485     return false;
2486   }
2487 }
2488 #endif
2489 
2490 bool G1CollectedHeap::obj_in_cs(oop obj) {
2491   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2492   return r != NULL && r->in_collection_set();
2493 }
2494 
2495 // Iteration functions.
2496 
2497 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2498 
2499 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2500   ExtendedOopClosure* _cl;
2501 public:
2502   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2503   bool doHeapRegion(HeapRegion* r) {
2504     if (!r->is_continues_humongous()) {
2505       r->oop_iterate(_cl);
2506     }
2507     return false;
2508   }
2509 };
2510 
2511 // Iterates an ObjectClosure over all objects within a HeapRegion.
2512 
2513 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2514   ObjectClosure* _cl;
2515 public:
2516   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2517   bool doHeapRegion(HeapRegion* r) {
2518     if (!r->is_continues_humongous()) {
2519       r->object_iterate(_cl);
2520     }
2521     return false;
2522   }
2523 };
2524 
2525 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2526   IterateObjectClosureRegionClosure blk(cl);
2527   heap_region_iterate(&blk);
2528 }
2529 
2530 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2531   _hrm.iterate(cl);
2532 }
2533 
2534 void
2535 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2536                                          uint worker_id,
2537                                          HeapRegionClaimer *hrclaimer,
2538                                          bool concurrent) const {
2539   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2540 }
2541 
2542 // Clear the cached CSet starting regions and (more importantly)
2543 // the time stamps. Called when we reset the GC time stamp.
2544 void G1CollectedHeap::clear_cset_start_regions() {
2545   assert(_worker_cset_start_region != NULL, "sanity");
2546   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2547 
2548   for (uint i = 0; i < ParallelGCThreads; i++) {
2549     _worker_cset_start_region[i] = NULL;
2550     _worker_cset_start_region_time_stamp[i] = 0;
2551   }
2552 }
2553 
2554 // Given the id of a worker, obtain or calculate a suitable
2555 // starting region for iterating over the current collection set.
2556 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2557   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2558 
2559   HeapRegion* result = NULL;
2560   unsigned gc_time_stamp = get_gc_time_stamp();
2561 
2562   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2563     // Cached starting region for current worker was set
2564     // during the current pause - so it's valid.
2565     // Note: the cached starting heap region may be NULL
2566     // (when the collection set is empty).
2567     result = _worker_cset_start_region[worker_i];
2568     assert(result == NULL || result->in_collection_set(), "sanity");
2569     return result;
2570   }
2571 
2572   // The cached entry was not valid so let's calculate
2573   // a suitable starting heap region for this worker.
2574 
2575   // We want the parallel threads to start their collection
2576   // set iteration at different collection set regions to
2577   // avoid contention.
2578   // If we have:
2579   //          n collection set regions
2580   //          p threads
2581   // Then thread t will start at region floor ((t * n) / p)
2582 
2583   result = g1_policy()->collection_set();
2584   uint cs_size = g1_policy()->cset_region_length();
2585   uint active_workers = workers()->active_workers();
2586 
2587   uint end_ind   = (cs_size * worker_i) / active_workers;
2588   uint start_ind = 0;
2589 
2590   if (worker_i > 0 &&
2591       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2592     // Previous workers starting region is valid
2593     // so let's iterate from there
2594     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2595     result = _worker_cset_start_region[worker_i - 1];
2596   }
2597 
2598   for (uint i = start_ind; i < end_ind; i++) {
2599     result = result->next_in_collection_set();
2600   }
2601 
2602   // Note: the calculated starting heap region may be NULL
2603   // (when the collection set is empty).
2604   assert(result == NULL || result->in_collection_set(), "sanity");
2605   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2606          "should be updated only once per pause");
2607   _worker_cset_start_region[worker_i] = result;
2608   OrderAccess::storestore();
2609   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2610   return result;
2611 }
2612 
2613 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2614   HeapRegion* r = g1_policy()->collection_set();
2615   while (r != NULL) {
2616     HeapRegion* next = r->next_in_collection_set();
2617     if (cl->doHeapRegion(r)) {
2618       cl->incomplete();
2619       return;
2620     }
2621     r = next;
2622   }
2623 }
2624 
2625 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2626                                                   HeapRegionClosure *cl) {
2627   if (r == NULL) {
2628     // The CSet is empty so there's nothing to do.
2629     return;
2630   }
2631 
2632   assert(r->in_collection_set(),
2633          "Start region must be a member of the collection set.");
2634   HeapRegion* cur = r;
2635   while (cur != NULL) {
2636     HeapRegion* next = cur->next_in_collection_set();
2637     if (cl->doHeapRegion(cur) && false) {
2638       cl->incomplete();
2639       return;
2640     }
2641     cur = next;
2642   }
2643   cur = g1_policy()->collection_set();
2644   while (cur != r) {
2645     HeapRegion* next = cur->next_in_collection_set();
2646     if (cl->doHeapRegion(cur) && false) {
2647       cl->incomplete();
2648       return;
2649     }
2650     cur = next;
2651   }
2652 }
2653 
2654 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2655   HeapRegion* result = _hrm.next_region_in_heap(from);
2656   while (result != NULL && result->is_pinned()) {
2657     result = _hrm.next_region_in_heap(result);
2658   }
2659   return result;
2660 }
2661 
2662 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2663   HeapRegion* hr = heap_region_containing(addr);
2664   return hr->block_start(addr);
2665 }
2666 
2667 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2668   HeapRegion* hr = heap_region_containing(addr);
2669   return hr->block_size(addr);
2670 }
2671 
2672 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2673   HeapRegion* hr = heap_region_containing(addr);
2674   return hr->block_is_obj(addr);
2675 }
2676 
2677 bool G1CollectedHeap::supports_tlab_allocation() const {
2678   return true;
2679 }
2680 
2681 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2682   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2683 }
2684 
2685 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2686   return young_list()->eden_used_bytes();
2687 }
2688 
2689 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2690 // must be equal to the humongous object limit.
2691 size_t G1CollectedHeap::max_tlab_size() const {
2692   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2693 }
2694 
2695 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2696   AllocationContext_t context = AllocationContext::current();
2697   return _allocator->unsafe_max_tlab_alloc(context);
2698 }
2699 
2700 size_t G1CollectedHeap::max_capacity() const {
2701   return _hrm.reserved().byte_size();
2702 }
2703 
2704 jlong G1CollectedHeap::millis_since_last_gc() {
2705   // assert(false, "NYI");
2706   return 0;
2707 }
2708 
2709 void G1CollectedHeap::prepare_for_verify() {
2710   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2711     ensure_parsability(false);
2712   }
2713   g1_rem_set()->prepare_for_verify();
2714 }
2715 
2716 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2717                                               VerifyOption vo) {
2718   switch (vo) {
2719   case VerifyOption_G1UsePrevMarking:
2720     return hr->obj_allocated_since_prev_marking(obj);
2721   case VerifyOption_G1UseNextMarking:
2722     return hr->obj_allocated_since_next_marking(obj);
2723   case VerifyOption_G1UseMarkWord:
2724     return false;
2725   default:
2726     ShouldNotReachHere();
2727   }
2728   return false; // keep some compilers happy
2729 }
2730 
2731 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2732   switch (vo) {
2733   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2734   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2735   case VerifyOption_G1UseMarkWord:    return NULL;
2736   default:                            ShouldNotReachHere();
2737   }
2738   return NULL; // keep some compilers happy
2739 }
2740 
2741 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2742   switch (vo) {
2743   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2744   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2745   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2746   default:                            ShouldNotReachHere();
2747   }
2748   return false; // keep some compilers happy
2749 }
2750 
2751 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2752   switch (vo) {
2753   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2754   case VerifyOption_G1UseNextMarking: return "NTAMS";
2755   case VerifyOption_G1UseMarkWord:    return "NONE";
2756   default:                            ShouldNotReachHere();
2757   }
2758   return NULL; // keep some compilers happy
2759 }
2760 
2761 class VerifyRootsClosure: public OopClosure {
2762 private:
2763   G1CollectedHeap* _g1h;
2764   VerifyOption     _vo;
2765   bool             _failures;
2766 public:
2767   // _vo == UsePrevMarking -> use "prev" marking information,
2768   // _vo == UseNextMarking -> use "next" marking information,
2769   // _vo == UseMarkWord    -> use mark word from object header.
2770   VerifyRootsClosure(VerifyOption vo) :
2771     _g1h(G1CollectedHeap::heap()),
2772     _vo(vo),
2773     _failures(false) { }
2774 
2775   bool failures() { return _failures; }
2776 
2777   template <class T> void do_oop_nv(T* p) {
2778     T heap_oop = oopDesc::load_heap_oop(p);
2779     if (!oopDesc::is_null(heap_oop)) {
2780       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2781       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2782         gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2783                                "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2784         if (_vo == VerifyOption_G1UseMarkWord) {
2785           gclog_or_tty->print_cr("  Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2786         }
2787         obj->print_on(gclog_or_tty);
2788         _failures = true;
2789       }
2790     }
2791   }
2792 
2793   void do_oop(oop* p)       { do_oop_nv(p); }
2794   void do_oop(narrowOop* p) { do_oop_nv(p); }
2795 };
2796 
2797 class G1VerifyCodeRootOopClosure: public OopClosure {
2798   G1CollectedHeap* _g1h;
2799   OopClosure* _root_cl;
2800   nmethod* _nm;
2801   VerifyOption _vo;
2802   bool _failures;
2803 
2804   template <class T> void do_oop_work(T* p) {
2805     // First verify that this root is live
2806     _root_cl->do_oop(p);
2807 
2808     if (!G1VerifyHeapRegionCodeRoots) {
2809       // We're not verifying the code roots attached to heap region.
2810       return;
2811     }
2812 
2813     // Don't check the code roots during marking verification in a full GC
2814     if (_vo == VerifyOption_G1UseMarkWord) {
2815       return;
2816     }
2817 
2818     // Now verify that the current nmethod (which contains p) is
2819     // in the code root list of the heap region containing the
2820     // object referenced by p.
2821 
2822     T heap_oop = oopDesc::load_heap_oop(p);
2823     if (!oopDesc::is_null(heap_oop)) {
2824       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2825 
2826       // Now fetch the region containing the object
2827       HeapRegion* hr = _g1h->heap_region_containing(obj);
2828       HeapRegionRemSet* hrrs = hr->rem_set();
2829       // Verify that the strong code root list for this region
2830       // contains the nmethod
2831       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2832         gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2833                                "from nmethod " PTR_FORMAT " not in strong "
2834                                "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2835                                p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2836         _failures = true;
2837       }
2838     }
2839   }
2840 
2841 public:
2842   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2843     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2844 
2845   void do_oop(oop* p) { do_oop_work(p); }
2846   void do_oop(narrowOop* p) { do_oop_work(p); }
2847 
2848   void set_nmethod(nmethod* nm) { _nm = nm; }
2849   bool failures() { return _failures; }
2850 };
2851 
2852 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2853   G1VerifyCodeRootOopClosure* _oop_cl;
2854 
2855 public:
2856   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2857     _oop_cl(oop_cl) {}
2858 
2859   void do_code_blob(CodeBlob* cb) {
2860     nmethod* nm = cb->as_nmethod_or_null();
2861     if (nm != NULL) {
2862       _oop_cl->set_nmethod(nm);
2863       nm->oops_do(_oop_cl);
2864     }
2865   }
2866 };
2867 
2868 class YoungRefCounterClosure : public OopClosure {
2869   G1CollectedHeap* _g1h;
2870   int              _count;
2871  public:
2872   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2873   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2874   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2875 
2876   int count() { return _count; }
2877   void reset_count() { _count = 0; };
2878 };
2879 
2880 class VerifyKlassClosure: public KlassClosure {
2881   YoungRefCounterClosure _young_ref_counter_closure;
2882   OopClosure *_oop_closure;
2883  public:
2884   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2885   void do_klass(Klass* k) {
2886     k->oops_do(_oop_closure);
2887 
2888     _young_ref_counter_closure.reset_count();
2889     k->oops_do(&_young_ref_counter_closure);
2890     if (_young_ref_counter_closure.count() > 0) {
2891       guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2892     }
2893   }
2894 };
2895 
2896 class VerifyLivenessOopClosure: public OopClosure {
2897   G1CollectedHeap* _g1h;
2898   VerifyOption _vo;
2899 public:
2900   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2901     _g1h(g1h), _vo(vo)
2902   { }
2903   void do_oop(narrowOop *p) { do_oop_work(p); }
2904   void do_oop(      oop *p) { do_oop_work(p); }
2905 
2906   template <class T> void do_oop_work(T *p) {
2907     oop obj = oopDesc::load_decode_heap_oop(p);
2908     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2909               "Dead object referenced by a not dead object");
2910   }
2911 };
2912 
2913 class VerifyObjsInRegionClosure: public ObjectClosure {
2914 private:
2915   G1CollectedHeap* _g1h;
2916   size_t _live_bytes;
2917   HeapRegion *_hr;
2918   VerifyOption _vo;
2919 public:
2920   // _vo == UsePrevMarking -> use "prev" marking information,
2921   // _vo == UseNextMarking -> use "next" marking information,
2922   // _vo == UseMarkWord    -> use mark word from object header.
2923   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2924     : _live_bytes(0), _hr(hr), _vo(vo) {
2925     _g1h = G1CollectedHeap::heap();
2926   }
2927   void do_object(oop o) {
2928     VerifyLivenessOopClosure isLive(_g1h, _vo);
2929     assert(o != NULL, "Huh?");
2930     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2931       // If the object is alive according to the mark word,
2932       // then verify that the marking information agrees.
2933       // Note we can't verify the contra-positive of the
2934       // above: if the object is dead (according to the mark
2935       // word), it may not be marked, or may have been marked
2936       // but has since became dead, or may have been allocated
2937       // since the last marking.
2938       if (_vo == VerifyOption_G1UseMarkWord) {
2939         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2940       }
2941 
2942       o->oop_iterate_no_header(&isLive);
2943       if (!_hr->obj_allocated_since_prev_marking(o)) {
2944         size_t obj_size = o->size();    // Make sure we don't overflow
2945         _live_bytes += (obj_size * HeapWordSize);
2946       }
2947     }
2948   }
2949   size_t live_bytes() { return _live_bytes; }
2950 };
2951 
2952 class VerifyArchiveOopClosure: public OopClosure {
2953 public:
2954   VerifyArchiveOopClosure(HeapRegion *hr) { }
2955   void do_oop(narrowOop *p) { do_oop_work(p); }
2956   void do_oop(      oop *p) { do_oop_work(p); }
2957 
2958   template <class T> void do_oop_work(T *p) {
2959     oop obj = oopDesc::load_decode_heap_oop(p);
2960     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2961               "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2962               p2i(p), p2i(obj));
2963   }
2964 };
2965 
2966 class VerifyArchiveRegionClosure: public ObjectClosure {
2967 public:
2968   VerifyArchiveRegionClosure(HeapRegion *hr) { }
2969   // Verify that all object pointers are to archive regions.
2970   void do_object(oop o) {
2971     VerifyArchiveOopClosure checkOop(NULL);
2972     assert(o != NULL, "Should not be here for NULL oops");
2973     o->oop_iterate_no_header(&checkOop);
2974   }
2975 };
2976 
2977 class VerifyRegionClosure: public HeapRegionClosure {
2978 private:
2979   bool             _par;
2980   VerifyOption     _vo;
2981   bool             _failures;
2982 public:
2983   // _vo == UsePrevMarking -> use "prev" marking information,
2984   // _vo == UseNextMarking -> use "next" marking information,
2985   // _vo == UseMarkWord    -> use mark word from object header.
2986   VerifyRegionClosure(bool par, VerifyOption vo)
2987     : _par(par),
2988       _vo(vo),
2989       _failures(false) {}
2990 
2991   bool failures() {
2992     return _failures;
2993   }
2994 
2995   bool doHeapRegion(HeapRegion* r) {
2996     // For archive regions, verify there are no heap pointers to
2997     // non-pinned regions. For all others, verify liveness info.
2998     if (r->is_archive()) {
2999       VerifyArchiveRegionClosure verify_oop_pointers(r);
3000       r->object_iterate(&verify_oop_pointers);
3001       return true;
3002     }
3003     if (!r->is_continues_humongous()) {
3004       bool failures = false;
3005       r->verify(_vo, &failures);
3006       if (failures) {
3007         _failures = true;
3008       } else if (!r->is_starts_humongous()) {
3009         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3010         r->object_iterate(&not_dead_yet_cl);
3011         if (_vo != VerifyOption_G1UseNextMarking) {
3012           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3013             gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3014                                    "max_live_bytes " SIZE_FORMAT " "
3015                                    "< calculated " SIZE_FORMAT,
3016                                    p2i(r->bottom()), p2i(r->end()),
3017                                    r->max_live_bytes(),
3018                                  not_dead_yet_cl.live_bytes());
3019             _failures = true;
3020           }
3021         } else {
3022           // When vo == UseNextMarking we cannot currently do a sanity
3023           // check on the live bytes as the calculation has not been
3024           // finalized yet.
3025         }
3026       }
3027     }
3028     return false; // stop the region iteration if we hit a failure
3029   }
3030 };
3031 
3032 // This is the task used for parallel verification of the heap regions
3033 
3034 class G1ParVerifyTask: public AbstractGangTask {
3035 private:
3036   G1CollectedHeap*  _g1h;
3037   VerifyOption      _vo;
3038   bool              _failures;
3039   HeapRegionClaimer _hrclaimer;
3040 
3041 public:
3042   // _vo == UsePrevMarking -> use "prev" marking information,
3043   // _vo == UseNextMarking -> use "next" marking information,
3044   // _vo == UseMarkWord    -> use mark word from object header.
3045   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3046       AbstractGangTask("Parallel verify task"),
3047       _g1h(g1h),
3048       _vo(vo),
3049       _failures(false),
3050       _hrclaimer(g1h->workers()->active_workers()) {}
3051 
3052   bool failures() {
3053     return _failures;
3054   }
3055 
3056   void work(uint worker_id) {
3057     HandleMark hm;
3058     VerifyRegionClosure blk(true, _vo);
3059     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3060     if (blk.failures()) {
3061       _failures = true;
3062     }
3063   }
3064 };
3065 
3066 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3067   if (SafepointSynchronize::is_at_safepoint()) {
3068     assert(Thread::current()->is_VM_thread(),
3069            "Expected to be executed serially by the VM thread at this point");
3070 
3071     if (!silent) { gclog_or_tty->print("Roots "); }
3072     VerifyRootsClosure rootsCl(vo);
3073     VerifyKlassClosure klassCl(this, &rootsCl);
3074     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3075 
3076     // We apply the relevant closures to all the oops in the
3077     // system dictionary, class loader data graph, the string table
3078     // and the nmethods in the code cache.
3079     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3080     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3081 
3082     {
3083       G1RootProcessor root_processor(this, 1);
3084       root_processor.process_all_roots(&rootsCl,
3085                                        &cldCl,
3086                                        &blobsCl);
3087     }
3088 
3089     bool failures = rootsCl.failures() || codeRootsCl.failures();
3090 
3091     if (vo != VerifyOption_G1UseMarkWord) {
3092       // If we're verifying during a full GC then the region sets
3093       // will have been torn down at the start of the GC. Therefore
3094       // verifying the region sets will fail. So we only verify
3095       // the region sets when not in a full GC.
3096       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3097       verify_region_sets();
3098     }
3099 
3100     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3101     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3102 
3103       G1ParVerifyTask task(this, vo);
3104       workers()->run_task(&task);
3105       if (task.failures()) {
3106         failures = true;
3107       }
3108 
3109     } else {
3110       VerifyRegionClosure blk(false, vo);
3111       heap_region_iterate(&blk);
3112       if (blk.failures()) {
3113         failures = true;
3114       }
3115     }
3116 
3117     if (G1StringDedup::is_enabled()) {
3118       if (!silent) gclog_or_tty->print("StrDedup ");
3119       G1StringDedup::verify();
3120     }
3121 
3122     if (failures) {
3123       gclog_or_tty->print_cr("Heap:");
3124       // It helps to have the per-region information in the output to
3125       // help us track down what went wrong. This is why we call
3126       // print_extended_on() instead of print_on().
3127       print_extended_on(gclog_or_tty);
3128       gclog_or_tty->cr();
3129       gclog_or_tty->flush();
3130     }
3131     guarantee(!failures, "there should not have been any failures");
3132   } else {
3133     if (!silent) {
3134       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3135       if (G1StringDedup::is_enabled()) {
3136         gclog_or_tty->print(", StrDedup");
3137       }
3138       gclog_or_tty->print(") ");
3139     }
3140   }
3141 }
3142 
3143 void G1CollectedHeap::verify(bool silent) {
3144   verify(silent, VerifyOption_G1UsePrevMarking);
3145 }
3146 
3147 double G1CollectedHeap::verify(bool guard, const char* msg) {
3148   double verify_time_ms = 0.0;
3149 
3150   if (guard && total_collections() >= VerifyGCStartAt) {
3151     double verify_start = os::elapsedTime();
3152     HandleMark hm;  // Discard invalid handles created during verification
3153     prepare_for_verify();
3154     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3155     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3156   }
3157 
3158   return verify_time_ms;
3159 }
3160 
3161 void G1CollectedHeap::verify_before_gc() {
3162   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3163   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3164 }
3165 
3166 void G1CollectedHeap::verify_after_gc() {
3167   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3168   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3169 }
3170 
3171 class PrintRegionClosure: public HeapRegionClosure {
3172   outputStream* _st;
3173 public:
3174   PrintRegionClosure(outputStream* st) : _st(st) {}
3175   bool doHeapRegion(HeapRegion* r) {
3176     r->print_on(_st);
3177     return false;
3178   }
3179 };
3180 
3181 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3182                                        const HeapRegion* hr,
3183                                        const VerifyOption vo) const {
3184   switch (vo) {
3185   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3186   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3187   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3188   default:                            ShouldNotReachHere();
3189   }
3190   return false; // keep some compilers happy
3191 }
3192 
3193 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3194                                        const VerifyOption vo) const {
3195   switch (vo) {
3196   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3197   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3198   case VerifyOption_G1UseMarkWord: {
3199     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3200     return !obj->is_gc_marked() && !hr->is_archive();
3201   }
3202   default:                            ShouldNotReachHere();
3203   }
3204   return false; // keep some compilers happy
3205 }
3206 
3207 void G1CollectedHeap::print_on(outputStream* st) const {
3208   st->print(" %-20s", "garbage-first heap");
3209   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3210             capacity()/K, used_unlocked()/K);
3211   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3212             p2i(_hrm.reserved().start()),
3213             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3214             p2i(_hrm.reserved().end()));
3215   st->cr();
3216   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3217   uint young_regions = _young_list->length();
3218   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3219             (size_t) young_regions * HeapRegion::GrainBytes / K);
3220   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3221   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3222             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3223   st->cr();
3224   MetaspaceAux::print_on(st);
3225 }
3226 
3227 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3228   print_on(st);
3229 
3230   // Print the per-region information.
3231   st->cr();
3232   st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3233                "HS=humongous(starts), HC=humongous(continues), "
3234                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3235                "PTAMS=previous top-at-mark-start, "
3236                "NTAMS=next top-at-mark-start)");
3237   PrintRegionClosure blk(st);
3238   heap_region_iterate(&blk);
3239 }
3240 
3241 void G1CollectedHeap::print_on_error(outputStream* st) const {
3242   this->CollectedHeap::print_on_error(st);
3243 
3244   if (_cm != NULL) {
3245     st->cr();
3246     _cm->print_on_error(st);
3247   }
3248 }
3249 
3250 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3251   workers()->print_worker_threads_on(st);
3252   _cmThread->print_on(st);
3253   st->cr();
3254   _cm->print_worker_threads_on(st);
3255   _cg1r->print_worker_threads_on(st);
3256   if (G1StringDedup::is_enabled()) {
3257     G1StringDedup::print_worker_threads_on(st);
3258   }
3259 }
3260 
3261 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3262   workers()->threads_do(tc);
3263   tc->do_thread(_cmThread);
3264   _cg1r->threads_do(tc);
3265   if (G1StringDedup::is_enabled()) {
3266     G1StringDedup::threads_do(tc);
3267   }
3268 }
3269 
3270 void G1CollectedHeap::print_tracing_info() const {
3271   // We'll overload this to mean "trace GC pause statistics."
3272   if (TraceYoungGenTime || TraceOldGenTime) {
3273     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3274     // to that.
3275     g1_policy()->print_tracing_info();
3276   }
3277   if (G1SummarizeRSetStats) {
3278     g1_rem_set()->print_summary_info();
3279   }
3280   if (G1SummarizeConcMark) {
3281     concurrent_mark()->print_summary_info();
3282   }
3283   g1_policy()->print_yg_surv_rate_info();
3284 }
3285 
3286 #ifndef PRODUCT
3287 // Helpful for debugging RSet issues.
3288 
3289 class PrintRSetsClosure : public HeapRegionClosure {
3290 private:
3291   const char* _msg;
3292   size_t _occupied_sum;
3293 
3294 public:
3295   bool doHeapRegion(HeapRegion* r) {
3296     HeapRegionRemSet* hrrs = r->rem_set();
3297     size_t occupied = hrrs->occupied();
3298     _occupied_sum += occupied;
3299 
3300     gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3301                            HR_FORMAT_PARAMS(r));
3302     if (occupied == 0) {
3303       gclog_or_tty->print_cr("  RSet is empty");
3304     } else {
3305       hrrs->print();
3306     }
3307     gclog_or_tty->print_cr("----------");
3308     return false;
3309   }
3310 
3311   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3312     gclog_or_tty->cr();
3313     gclog_or_tty->print_cr("========================================");
3314     gclog_or_tty->print_cr("%s", msg);
3315     gclog_or_tty->cr();
3316   }
3317 
3318   ~PrintRSetsClosure() {
3319     gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3320     gclog_or_tty->print_cr("========================================");
3321     gclog_or_tty->cr();
3322   }
3323 };
3324 
3325 void G1CollectedHeap::print_cset_rsets() {
3326   PrintRSetsClosure cl("Printing CSet RSets");
3327   collection_set_iterate(&cl);
3328 }
3329 
3330 void G1CollectedHeap::print_all_rsets() {
3331   PrintRSetsClosure cl("Printing All RSets");;
3332   heap_region_iterate(&cl);
3333 }
3334 #endif // PRODUCT
3335 
3336 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3337   YoungList* young_list = heap()->young_list();
3338 
3339   size_t eden_used_bytes = young_list->eden_used_bytes();
3340   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3341 
3342   size_t eden_capacity_bytes =
3343     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3344 
3345   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3346   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3347 }
3348 
3349 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3350   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3351                        stats->unused(), stats->used(), stats->region_end_waste(),
3352                        stats->regions_filled(), stats->direct_allocated(),
3353                        stats->failure_used(), stats->failure_waste());
3354 }
3355 
3356 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3357   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3358   gc_tracer->report_gc_heap_summary(when, heap_summary);
3359 
3360   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3361   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3362 }
3363 
3364 
3365 G1CollectedHeap* G1CollectedHeap::heap() {
3366   CollectedHeap* heap = Universe::heap();
3367   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3368   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3369   return (G1CollectedHeap*)heap;
3370 }
3371 
3372 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3373   // always_do_update_barrier = false;
3374   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3375   // Fill TLAB's and such
3376   accumulate_statistics_all_tlabs();
3377   ensure_parsability(true);
3378 
3379   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3380       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3381     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3382   }
3383 }
3384 
3385 void G1CollectedHeap::gc_epilogue(bool full) {
3386 
3387   if (G1SummarizeRSetStats &&
3388       (G1SummarizeRSetStatsPeriod > 0) &&
3389       // we are at the end of the GC. Total collections has already been increased.
3390       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3391     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3392   }
3393 
3394   // FIXME: what is this about?
3395   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3396   // is set.
3397 #if defined(COMPILER2) || INCLUDE_JVMCI
3398   assert(DerivedPointerTable::is_empty(), "derived pointer present");
3399 #endif
3400   // always_do_update_barrier = true;
3401 
3402   resize_all_tlabs();
3403   allocation_context_stats().update(full);
3404 
3405   // We have just completed a GC. Update the soft reference
3406   // policy with the new heap occupancy
3407   Universe::update_heap_info_at_gc();
3408 }
3409 
3410 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3411                                                uint gc_count_before,
3412                                                bool* succeeded,
3413                                                GCCause::Cause gc_cause) {
3414   assert_heap_not_locked_and_not_at_safepoint();
3415   g1_policy()->record_stop_world_start();
3416   VM_G1IncCollectionPause op(gc_count_before,
3417                              word_size,
3418                              false, /* should_initiate_conc_mark */
3419                              g1_policy()->max_pause_time_ms(),
3420                              gc_cause);
3421 
3422   op.set_allocation_context(AllocationContext::current());
3423   VMThread::execute(&op);
3424 
3425   HeapWord* result = op.result();
3426   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3427   assert(result == NULL || ret_succeeded,
3428          "the result should be NULL if the VM did not succeed");
3429   *succeeded = ret_succeeded;
3430 
3431   assert_heap_not_locked();
3432   return result;
3433 }
3434 
3435 void
3436 G1CollectedHeap::doConcurrentMark() {
3437   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3438   if (!_cmThread->in_progress()) {
3439     _cmThread->set_started();
3440     CGC_lock->notify();
3441   }
3442 }
3443 
3444 size_t G1CollectedHeap::pending_card_num() {
3445   size_t extra_cards = 0;
3446   JavaThread *curr = Threads::first();
3447   while (curr != NULL) {
3448     DirtyCardQueue& dcq = curr->dirty_card_queue();
3449     extra_cards += dcq.size();
3450     curr = curr->next();
3451   }
3452   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3453   size_t buffer_size = dcqs.buffer_size();
3454   size_t buffer_num = dcqs.completed_buffers_num();
3455 
3456   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3457   // in bytes - not the number of 'entries'. We need to convert
3458   // into a number of cards.
3459   return (buffer_size * buffer_num + extra_cards) / oopSize;
3460 }
3461 
3462 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3463  private:
3464   size_t _total_humongous;
3465   size_t _candidate_humongous;
3466 
3467   DirtyCardQueue _dcq;
3468 
3469   // We don't nominate objects with many remembered set entries, on
3470   // the assumption that such objects are likely still live.
3471   bool is_remset_small(HeapRegion* region) const {
3472     HeapRegionRemSet* const rset = region->rem_set();
3473     return G1EagerReclaimHumongousObjectsWithStaleRefs
3474       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3475       : rset->is_empty();
3476   }
3477 
3478   bool is_typeArray_region(HeapRegion* region) const {
3479     return oop(region->bottom())->is_typeArray();
3480   }
3481 
3482   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3483     assert(region->is_starts_humongous(), "Must start a humongous object");
3484 
3485     // Candidate selection must satisfy the following constraints
3486     // while concurrent marking is in progress:
3487     //
3488     // * In order to maintain SATB invariants, an object must not be
3489     // reclaimed if it was allocated before the start of marking and
3490     // has not had its references scanned.  Such an object must have
3491     // its references (including type metadata) scanned to ensure no
3492     // live objects are missed by the marking process.  Objects
3493     // allocated after the start of concurrent marking don't need to
3494     // be scanned.
3495     //
3496     // * An object must not be reclaimed if it is on the concurrent
3497     // mark stack.  Objects allocated after the start of concurrent
3498     // marking are never pushed on the mark stack.
3499     //
3500     // Nominating only objects allocated after the start of concurrent
3501     // marking is sufficient to meet both constraints.  This may miss
3502     // some objects that satisfy the constraints, but the marking data
3503     // structures don't support efficiently performing the needed
3504     // additional tests or scrubbing of the mark stack.
3505     //
3506     // However, we presently only nominate is_typeArray() objects.
3507     // A humongous object containing references induces remembered
3508     // set entries on other regions.  In order to reclaim such an
3509     // object, those remembered sets would need to be cleaned up.
3510     //
3511     // We also treat is_typeArray() objects specially, allowing them
3512     // to be reclaimed even if allocated before the start of
3513     // concurrent mark.  For this we rely on mark stack insertion to
3514     // exclude is_typeArray() objects, preventing reclaiming an object
3515     // that is in the mark stack.  We also rely on the metadata for
3516     // such objects to be built-in and so ensured to be kept live.
3517     // Frequent allocation and drop of large binary blobs is an
3518     // important use case for eager reclaim, and this special handling
3519     // may reduce needed headroom.
3520 
3521     return is_typeArray_region(region) && is_remset_small(region);
3522   }
3523 
3524  public:
3525   RegisterHumongousWithInCSetFastTestClosure()
3526   : _total_humongous(0),
3527     _candidate_humongous(0),
3528     _dcq(&JavaThread::dirty_card_queue_set()) {
3529   }
3530 
3531   virtual bool doHeapRegion(HeapRegion* r) {
3532     if (!r->is_starts_humongous()) {
3533       return false;
3534     }
3535     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3536 
3537     bool is_candidate = humongous_region_is_candidate(g1h, r);
3538     uint rindex = r->hrm_index();
3539     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3540     if (is_candidate) {
3541       _candidate_humongous++;
3542       g1h->register_humongous_region_with_cset(rindex);
3543       // Is_candidate already filters out humongous object with large remembered sets.
3544       // If we have a humongous object with a few remembered sets, we simply flush these
3545       // remembered set entries into the DCQS. That will result in automatic
3546       // re-evaluation of their remembered set entries during the following evacuation
3547       // phase.
3548       if (!r->rem_set()->is_empty()) {
3549         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3550                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3551         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3552         HeapRegionRemSetIterator hrrs(r->rem_set());
3553         size_t card_index;
3554         while (hrrs.has_next(card_index)) {
3555           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3556           // The remembered set might contain references to already freed
3557           // regions. Filter out such entries to avoid failing card table
3558           // verification.
3559           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3560             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3561               *card_ptr = CardTableModRefBS::dirty_card_val();
3562               _dcq.enqueue(card_ptr);
3563             }
3564           }
3565         }
3566         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3567                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3568                hrrs.n_yielded(), r->rem_set()->occupied());
3569         r->rem_set()->clear_locked();
3570       }
3571       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3572     }
3573     _total_humongous++;
3574 
3575     return false;
3576   }
3577 
3578   size_t total_humongous() const { return _total_humongous; }
3579   size_t candidate_humongous() const { return _candidate_humongous; }
3580 
3581   void flush_rem_set_entries() { _dcq.flush(); }
3582 };
3583 
3584 void G1CollectedHeap::register_humongous_regions_with_cset() {
3585   if (!G1EagerReclaimHumongousObjects) {
3586     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3587     return;
3588   }
3589   double time = os::elapsed_counter();
3590 
3591   // Collect reclaim candidate information and register candidates with cset.
3592   RegisterHumongousWithInCSetFastTestClosure cl;
3593   heap_region_iterate(&cl);
3594 
3595   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3596   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3597                                                                   cl.total_humongous(),
3598                                                                   cl.candidate_humongous());
3599   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3600 
3601   // Finally flush all remembered set entries to re-check into the global DCQS.
3602   cl.flush_rem_set_entries();
3603 }
3604 
3605 #ifdef ASSERT
3606 class VerifyCSetClosure: public HeapRegionClosure {
3607 public:
3608   bool doHeapRegion(HeapRegion* hr) {
3609     // Here we check that the CSet region's RSet is ready for parallel
3610     // iteration. The fields that we'll verify are only manipulated
3611     // when the region is part of a CSet and is collected. Afterwards,
3612     // we reset these fields when we clear the region's RSet (when the
3613     // region is freed) so they are ready when the region is
3614     // re-allocated. The only exception to this is if there's an
3615     // evacuation failure and instead of freeing the region we leave
3616     // it in the heap. In that case, we reset these fields during
3617     // evacuation failure handling.
3618     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3619 
3620     // Here's a good place to add any other checks we'd like to
3621     // perform on CSet regions.
3622     return false;
3623   }
3624 };
3625 #endif // ASSERT
3626 
3627 uint G1CollectedHeap::num_task_queues() const {
3628   return _task_queues->size();
3629 }
3630 
3631 #if TASKQUEUE_STATS
3632 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3633   st->print_raw_cr("GC Task Stats");
3634   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3635   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3636 }
3637 
3638 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3639   print_taskqueue_stats_hdr(st);
3640 
3641   TaskQueueStats totals;
3642   const uint n = num_task_queues();
3643   for (uint i = 0; i < n; ++i) {
3644     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3645     totals += task_queue(i)->stats;
3646   }
3647   st->print_raw("tot "); totals.print(st); st->cr();
3648 
3649   DEBUG_ONLY(totals.verify());
3650 }
3651 
3652 void G1CollectedHeap::reset_taskqueue_stats() {
3653   const uint n = num_task_queues();
3654   for (uint i = 0; i < n; ++i) {
3655     task_queue(i)->stats.reset();
3656   }
3657 }
3658 #endif // TASKQUEUE_STATS
3659 
3660 void G1CollectedHeap::log_gc_header() {
3661   if (!G1Log::fine()) {
3662     return;
3663   }
3664 
3665   gclog_or_tty->gclog_stamp();
3666 
3667   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3668     .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3669     .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3670 
3671   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3672 }
3673 
3674 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3675   if (!G1Log::fine()) {
3676     return;
3677   }
3678 
3679   if (G1Log::finer()) {
3680     if (evacuation_failed()) {
3681       gclog_or_tty->print(" (to-space exhausted)");
3682     }
3683     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3684     g1_policy()->print_phases(pause_time_sec);
3685     g1_policy()->print_detailed_heap_transition();
3686   } else {
3687     if (evacuation_failed()) {
3688       gclog_or_tty->print("--");
3689     }
3690     g1_policy()->print_heap_transition();
3691     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3692   }
3693   gclog_or_tty->flush();
3694 }
3695 
3696 void G1CollectedHeap::wait_for_root_region_scanning() {
3697   double scan_wait_start = os::elapsedTime();
3698   // We have to wait until the CM threads finish scanning the
3699   // root regions as it's the only way to ensure that all the
3700   // objects on them have been correctly scanned before we start
3701   // moving them during the GC.
3702   bool waited = _cm->root_regions()->wait_until_scan_finished();
3703   double wait_time_ms = 0.0;
3704   if (waited) {
3705     double scan_wait_end = os::elapsedTime();
3706     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3707   }
3708   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3709 }
3710 
3711 bool
3712 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3713   assert_at_safepoint(true /* should_be_vm_thread */);
3714   guarantee(!is_gc_active(), "collection is not reentrant");
3715 
3716   if (GC_locker::check_active_before_gc()) {
3717     return false;
3718   }
3719 
3720   _gc_timer_stw->register_gc_start();
3721 
3722   GCIdMark gc_id_mark;
3723   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3724 
3725   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3726   ResourceMark rm;
3727 
3728   wait_for_root_region_scanning();
3729 
3730   G1Log::update_level();
3731   print_heap_before_gc();
3732   trace_heap_before_gc(_gc_tracer_stw);
3733 
3734   verify_region_sets_optional();
3735   verify_dirty_young_regions();
3736 
3737   // This call will decide whether this pause is an initial-mark
3738   // pause. If it is, during_initial_mark_pause() will return true
3739   // for the duration of this pause.
3740   g1_policy()->decide_on_conc_mark_initiation();
3741 
3742   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3743   assert(!collector_state()->during_initial_mark_pause() ||
3744           collector_state()->gcs_are_young(), "sanity");
3745 
3746   // We also do not allow mixed GCs during marking.
3747   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3748 
3749   // Record whether this pause is an initial mark. When the current
3750   // thread has completed its logging output and it's safe to signal
3751   // the CM thread, the flag's value in the policy has been reset.
3752   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3753 
3754   // Inner scope for scope based logging, timers, and stats collection
3755   {
3756     EvacuationInfo evacuation_info;
3757 
3758     if (collector_state()->during_initial_mark_pause()) {
3759       // We are about to start a marking cycle, so we increment the
3760       // full collection counter.
3761       increment_old_marking_cycles_started();
3762       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3763     }
3764 
3765     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3766 
3767     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3768 
3769     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3770                                                                   workers()->active_workers(),
3771                                                                   Threads::number_of_non_daemon_threads());
3772     workers()->set_active_workers(active_workers);
3773 
3774     double pause_start_sec = os::elapsedTime();
3775     g1_policy()->note_gc_start(active_workers);
3776     log_gc_header();
3777 
3778     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3779     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3780 
3781     // If the secondary_free_list is not empty, append it to the
3782     // free_list. No need to wait for the cleanup operation to finish;
3783     // the region allocation code will check the secondary_free_list
3784     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3785     // set, skip this step so that the region allocation code has to
3786     // get entries from the secondary_free_list.
3787     if (!G1StressConcRegionFreeing) {
3788       append_secondary_free_list_if_not_empty_with_lock();
3789     }
3790 
3791     assert(check_young_list_well_formed(), "young list should be well formed");
3792 
3793     // Don't dynamically change the number of GC threads this early.  A value of
3794     // 0 is used to indicate serial work.  When parallel work is done,
3795     // it will be set.
3796 
3797     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3798       IsGCActiveMark x;
3799 
3800       gc_prologue(false);
3801       increment_total_collections(false /* full gc */);
3802       increment_gc_time_stamp();
3803 
3804       verify_before_gc();
3805 
3806       check_bitmaps("GC Start");
3807 
3808 #if defined(COMPILER2) || INCLUDE_JVMCI
3809       DerivedPointerTable::clear();
3810 #endif
3811 
3812       // Please see comment in g1CollectedHeap.hpp and
3813       // G1CollectedHeap::ref_processing_init() to see how
3814       // reference processing currently works in G1.
3815 
3816       // Enable discovery in the STW reference processor
3817       ref_processor_stw()->enable_discovery();
3818 
3819       {
3820         // We want to temporarily turn off discovery by the
3821         // CM ref processor, if necessary, and turn it back on
3822         // on again later if we do. Using a scoped
3823         // NoRefDiscovery object will do this.
3824         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3825 
3826         // Forget the current alloc region (we might even choose it to be part
3827         // of the collection set!).
3828         _allocator->release_mutator_alloc_region();
3829 
3830         // We should call this after we retire the mutator alloc
3831         // region(s) so that all the ALLOC / RETIRE events are generated
3832         // before the start GC event.
3833         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3834 
3835         // This timing is only used by the ergonomics to handle our pause target.
3836         // It is unclear why this should not include the full pause. We will
3837         // investigate this in CR 7178365.
3838         //
3839         // Preserving the old comment here if that helps the investigation:
3840         //
3841         // The elapsed time induced by the start time below deliberately elides
3842         // the possible verification above.
3843         double sample_start_time_sec = os::elapsedTime();
3844 
3845         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3846 
3847         if (collector_state()->during_initial_mark_pause()) {
3848           concurrent_mark()->checkpointRootsInitialPre();
3849         }
3850 
3851         double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3852         g1_policy()->finalize_old_cset_part(time_remaining_ms);
3853 
3854         evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3855 
3856         // Make sure the remembered sets are up to date. This needs to be
3857         // done before register_humongous_regions_with_cset(), because the
3858         // remembered sets are used there to choose eager reclaim candidates.
3859         // If the remembered sets are not up to date we might miss some
3860         // entries that need to be handled.
3861         g1_rem_set()->cleanupHRRS();
3862 
3863         register_humongous_regions_with_cset();
3864 
3865         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3866 
3867         _cm->note_start_of_gc();
3868         // We call this after finalize_cset() to
3869         // ensure that the CSet has been finalized.
3870         _cm->verify_no_cset_oops();
3871 
3872         if (_hr_printer.is_active()) {
3873           HeapRegion* hr = g1_policy()->collection_set();
3874           while (hr != NULL) {
3875             _hr_printer.cset(hr);
3876             hr = hr->next_in_collection_set();
3877           }
3878         }
3879 
3880 #ifdef ASSERT
3881         VerifyCSetClosure cl;
3882         collection_set_iterate(&cl);
3883 #endif // ASSERT
3884 
3885         // Initialize the GC alloc regions.
3886         _allocator->init_gc_alloc_regions(evacuation_info);
3887 
3888         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3889         pre_evacuate_collection_set();
3890 
3891         // Actually do the work...
3892         evacuate_collection_set(evacuation_info, &per_thread_states);
3893 
3894         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3895 
3896         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3897         free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3898 
3899         eagerly_reclaim_humongous_regions();
3900 
3901         g1_policy()->clear_collection_set();
3902 
3903         // Start a new incremental collection set for the next pause.
3904         g1_policy()->start_incremental_cset_building();
3905 
3906         clear_cset_fast_test();
3907 
3908         _young_list->reset_sampled_info();
3909 
3910         // Don't check the whole heap at this point as the
3911         // GC alloc regions from this pause have been tagged
3912         // as survivors and moved on to the survivor list.
3913         // Survivor regions will fail the !is_young() check.
3914         assert(check_young_list_empty(false /* check_heap */),
3915           "young list should be empty");
3916 
3917         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3918                                              _young_list->first_survivor_region(),
3919                                              _young_list->last_survivor_region());
3920 
3921         _young_list->reset_auxilary_lists();
3922 
3923         if (evacuation_failed()) {
3924           set_used(recalculate_used());
3925           if (_archive_allocator != NULL) {
3926             _archive_allocator->clear_used();
3927           }
3928           for (uint i = 0; i < ParallelGCThreads; i++) {
3929             if (_evacuation_failed_info_array[i].has_failed()) {
3930               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3931             }
3932           }
3933         } else {
3934           // The "used" of the the collection set have already been subtracted
3935           // when they were freed.  Add in the bytes evacuated.
3936           increase_used(g1_policy()->bytes_copied_during_gc());
3937         }
3938 
3939         if (collector_state()->during_initial_mark_pause()) {
3940           // We have to do this before we notify the CM threads that
3941           // they can start working to make sure that all the
3942           // appropriate initialization is done on the CM object.
3943           concurrent_mark()->checkpointRootsInitialPost();
3944           collector_state()->set_mark_in_progress(true);
3945           // Note that we don't actually trigger the CM thread at
3946           // this point. We do that later when we're sure that
3947           // the current thread has completed its logging output.
3948         }
3949 
3950         allocate_dummy_regions();
3951 
3952         _allocator->init_mutator_alloc_region();
3953 
3954         {
3955           size_t expand_bytes = g1_policy()->expansion_amount();
3956           if (expand_bytes > 0) {
3957             size_t bytes_before = capacity();
3958             // No need for an ergo verbose message here,
3959             // expansion_amount() does this when it returns a value > 0.
3960             double expand_ms;
3961             if (!expand(expand_bytes, &expand_ms)) {
3962               // We failed to expand the heap. Cannot do anything about it.
3963             }
3964             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3965           }
3966         }
3967 
3968         // We redo the verification but now wrt to the new CSet which
3969         // has just got initialized after the previous CSet was freed.
3970         _cm->verify_no_cset_oops();
3971         _cm->note_end_of_gc();
3972 
3973         // This timing is only used by the ergonomics to handle our pause target.
3974         // It is unclear why this should not include the full pause. We will
3975         // investigate this in CR 7178365.
3976         double sample_end_time_sec = os::elapsedTime();
3977         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3978         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3979         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3980 
3981         evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3982         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3983 
3984         MemoryService::track_memory_usage();
3985 
3986         // In prepare_for_verify() below we'll need to scan the deferred
3987         // update buffers to bring the RSets up-to-date if
3988         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3989         // the update buffers we'll probably need to scan cards on the
3990         // regions we just allocated to (i.e., the GC alloc
3991         // regions). However, during the last GC we called
3992         // set_saved_mark() on all the GC alloc regions, so card
3993         // scanning might skip the [saved_mark_word()...top()] area of
3994         // those regions (i.e., the area we allocated objects into
3995         // during the last GC). But it shouldn't. Given that
3996         // saved_mark_word() is conditional on whether the GC time stamp
3997         // on the region is current or not, by incrementing the GC time
3998         // stamp here we invalidate all the GC time stamps on all the
3999         // regions and saved_mark_word() will simply return top() for
4000         // all the regions. This is a nicer way of ensuring this rather
4001         // than iterating over the regions and fixing them. In fact, the
4002         // GC time stamp increment here also ensures that
4003         // saved_mark_word() will return top() between pauses, i.e.,
4004         // during concurrent refinement. So we don't need the
4005         // is_gc_active() check to decided which top to use when
4006         // scanning cards (see CR 7039627).
4007         increment_gc_time_stamp();
4008 
4009         verify_after_gc();
4010         check_bitmaps("GC End");
4011 
4012         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4013         ref_processor_stw()->verify_no_references_recorded();
4014 
4015         // CM reference discovery will be re-enabled if necessary.
4016       }
4017 
4018       // We should do this after we potentially expand the heap so
4019       // that all the COMMIT events are generated before the end GC
4020       // event, and after we retire the GC alloc regions so that all
4021       // RETIRE events are generated before the end GC event.
4022       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4023 
4024 #ifdef TRACESPINNING
4025       ParallelTaskTerminator::print_termination_counts();
4026 #endif
4027 
4028       gc_epilogue(false);
4029     }
4030 
4031     // Print the remainder of the GC log output.
4032     log_gc_footer(os::elapsedTime() - pause_start_sec);
4033 
4034     // It is not yet to safe to tell the concurrent mark to
4035     // start as we have some optional output below. We don't want the
4036     // output from the concurrent mark thread interfering with this
4037     // logging output either.
4038 
4039     _hrm.verify_optional();
4040     verify_region_sets_optional();
4041 
4042     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4043     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4044 
4045     print_heap_after_gc();
4046     trace_heap_after_gc(_gc_tracer_stw);
4047 
4048     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4049     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4050     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4051     // before any GC notifications are raised.
4052     g1mm()->update_sizes();
4053 
4054     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4055     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4056     _gc_timer_stw->register_gc_end();
4057     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4058   }
4059   // It should now be safe to tell the concurrent mark thread to start
4060   // without its logging output interfering with the logging output
4061   // that came from the pause.
4062 
4063   if (should_start_conc_mark) {
4064     // CAUTION: after the doConcurrentMark() call below,
4065     // the concurrent marking thread(s) could be running
4066     // concurrently with us. Make sure that anything after
4067     // this point does not assume that we are the only GC thread
4068     // running. Note: of course, the actual marking work will
4069     // not start until the safepoint itself is released in
4070     // SuspendibleThreadSet::desynchronize().
4071     doConcurrentMark();
4072   }
4073 
4074   return true;
4075 }
4076 
4077 void G1CollectedHeap::remove_self_forwarding_pointers() {
4078   double remove_self_forwards_start = os::elapsedTime();
4079 
4080   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4081   workers()->run_task(&rsfp_task);
4082 
4083   // Now restore saved marks, if any.
4084   for (uint i = 0; i < ParallelGCThreads; i++) {
4085     OopAndMarkOopStack& cur = _preserved_objs[i];
4086     while (!cur.is_empty()) {
4087       OopAndMarkOop elem = cur.pop();
4088       elem.set_mark();
4089     }
4090     cur.clear(true);
4091   }
4092 
4093   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4094 }
4095 
4096 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4097   if (!_evacuation_failed) {
4098     _evacuation_failed = true;
4099   }
4100 
4101   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4102 
4103   // We want to call the "for_promotion_failure" version only in the
4104   // case of a promotion failure.
4105   if (m->must_be_preserved_for_promotion_failure(obj)) {
4106     OopAndMarkOop elem(obj, m);
4107     _preserved_objs[worker_id].push(elem);
4108   }
4109 }
4110 
4111 class G1ParEvacuateFollowersClosure : public VoidClosure {
4112 private:
4113   double _start_term;
4114   double _term_time;
4115   size_t _term_attempts;
4116 
4117   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4118   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4119 protected:
4120   G1CollectedHeap*              _g1h;
4121   G1ParScanThreadState*         _par_scan_state;
4122   RefToScanQueueSet*            _queues;
4123   ParallelTaskTerminator*       _terminator;
4124 
4125   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4126   RefToScanQueueSet*      queues()         { return _queues; }
4127   ParallelTaskTerminator* terminator()     { return _terminator; }
4128 
4129 public:
4130   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4131                                 G1ParScanThreadState* par_scan_state,
4132                                 RefToScanQueueSet* queues,
4133                                 ParallelTaskTerminator* terminator)
4134     : _g1h(g1h), _par_scan_state(par_scan_state),
4135       _queues(queues), _terminator(terminator),
4136       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4137 
4138   void do_void();
4139 
4140   double term_time() const { return _term_time; }
4141   size_t term_attempts() const { return _term_attempts; }
4142 
4143 private:
4144   inline bool offer_termination();
4145 };
4146 
4147 bool G1ParEvacuateFollowersClosure::offer_termination() {
4148   G1ParScanThreadState* const pss = par_scan_state();
4149   start_term_time();
4150   const bool res = terminator()->offer_termination();
4151   end_term_time();
4152   return res;
4153 }
4154 
4155 void G1ParEvacuateFollowersClosure::do_void() {
4156   G1ParScanThreadState* const pss = par_scan_state();
4157   pss->trim_queue();
4158   do {
4159     pss->steal_and_trim_queue(queues());
4160   } while (!offer_termination());
4161 }
4162 
4163 class G1ParTask : public AbstractGangTask {
4164 protected:
4165   G1CollectedHeap*         _g1h;
4166   G1ParScanThreadStateSet* _pss;
4167   RefToScanQueueSet*       _queues;
4168   G1RootProcessor*         _root_processor;
4169   ParallelTaskTerminator   _terminator;
4170   uint                     _n_workers;
4171 
4172 public:
4173   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4174     : AbstractGangTask("G1 collection"),
4175       _g1h(g1h),
4176       _pss(per_thread_states),
4177       _queues(task_queues),
4178       _root_processor(root_processor),
4179       _terminator(n_workers, _queues),
4180       _n_workers(n_workers)
4181   {}
4182 
4183   void work(uint worker_id) {
4184     if (worker_id >= _n_workers) return;  // no work needed this round
4185 
4186     double start_sec = os::elapsedTime();
4187     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4188 
4189     {
4190       ResourceMark rm;
4191       HandleMark   hm;
4192 
4193       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4194 
4195       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
4196       pss->set_ref_processor(rp);
4197 
4198       double start_strong_roots_sec = os::elapsedTime();
4199 
4200       _root_processor->evacuate_roots(pss->closures(), worker_id);
4201 
4202       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4203 
4204       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4205       // treating the nmethods visited to act as roots for concurrent marking.
4206       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4207       // objects copied by the current evacuation.
4208       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4209                                                                              pss->closures()->weak_codeblobs(),
4210                                                                              worker_id);
4211 
4212       _pss->add_cards_scanned(worker_id, cards_scanned);
4213 
4214       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4215 
4216       double term_sec = 0.0;
4217       size_t evac_term_attempts = 0;
4218       {
4219         double start = os::elapsedTime();
4220         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4221         evac.do_void();
4222 
4223         evac_term_attempts = evac.term_attempts();
4224         term_sec = evac.term_time();
4225         double elapsed_sec = os::elapsedTime() - start;
4226         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4227         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4228         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4229       }
4230 
4231       assert(pss->queue_is_empty(), "should be empty");
4232 
4233       if (PrintTerminationStats) {
4234         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4235         size_t lab_waste;
4236         size_t lab_undo_waste;
4237         pss->waste(lab_waste, lab_undo_waste);
4238         _g1h->print_termination_stats(gclog_or_tty,
4239                                       worker_id,
4240                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
4241                                       strong_roots_sec * 1000.0,                  /* strong roots time */
4242                                       term_sec * 1000.0,                          /* evac term time */
4243                                       evac_term_attempts,                         /* evac term attempts */
4244                                       lab_waste,                                  /* alloc buffer waste */
4245                                       lab_undo_waste                              /* undo waste */
4246                                       );
4247       }
4248 
4249       // Close the inner scope so that the ResourceMark and HandleMark
4250       // destructors are executed here and are included as part of the
4251       // "GC Worker Time".
4252     }
4253     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4254   }
4255 };
4256 
4257 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4258   st->print_raw_cr("GC Termination Stats");
4259   st->print_raw_cr("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
4260   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts  total   alloc    undo");
4261   st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4262 }
4263 
4264 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4265                                               uint worker_id,
4266                                               double elapsed_ms,
4267                                               double strong_roots_ms,
4268                                               double term_ms,
4269                                               size_t term_attempts,
4270                                               size_t alloc_buffer_waste,
4271                                               size_t undo_waste) const {
4272   st->print_cr("%3d %9.2f %9.2f %6.2f "
4273                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4274                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4275                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4276                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4277                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4278                alloc_buffer_waste * HeapWordSize / K,
4279                undo_waste * HeapWordSize / K);
4280 }
4281 
4282 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4283 private:
4284   BoolObjectClosure* _is_alive;
4285   int _initial_string_table_size;
4286   int _initial_symbol_table_size;
4287 
4288   bool  _process_strings;
4289   int _strings_processed;
4290   int _strings_removed;
4291 
4292   bool  _process_symbols;
4293   int _symbols_processed;
4294   int _symbols_removed;
4295 
4296 public:
4297   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4298     AbstractGangTask("String/Symbol Unlinking"),
4299     _is_alive(is_alive),
4300     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4301     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4302 
4303     _initial_string_table_size = StringTable::the_table()->table_size();
4304     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4305     if (process_strings) {
4306       StringTable::clear_parallel_claimed_index();
4307     }
4308     if (process_symbols) {
4309       SymbolTable::clear_parallel_claimed_index();
4310     }
4311   }
4312 
4313   ~G1StringSymbolTableUnlinkTask() {
4314     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4315               "claim value %d after unlink less than initial string table size %d",
4316               StringTable::parallel_claimed_index(), _initial_string_table_size);
4317     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4318               "claim value %d after unlink less than initial symbol table size %d",
4319               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4320 
4321     if (G1TraceStringSymbolTableScrubbing) {
4322       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4323                              "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4324                              "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4325                              strings_processed(), strings_removed(),
4326                              symbols_processed(), symbols_removed());
4327     }
4328   }
4329 
4330   void work(uint worker_id) {
4331     int strings_processed = 0;
4332     int strings_removed = 0;
4333     int symbols_processed = 0;
4334     int symbols_removed = 0;
4335     if (_process_strings) {
4336       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4337       Atomic::add(strings_processed, &_strings_processed);
4338       Atomic::add(strings_removed, &_strings_removed);
4339     }
4340     if (_process_symbols) {
4341       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4342       Atomic::add(symbols_processed, &_symbols_processed);
4343       Atomic::add(symbols_removed, &_symbols_removed);
4344     }
4345   }
4346 
4347   size_t strings_processed() const { return (size_t)_strings_processed; }
4348   size_t strings_removed()   const { return (size_t)_strings_removed; }
4349 
4350   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4351   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4352 };
4353 
4354 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4355 private:
4356   static Monitor* _lock;
4357 
4358   BoolObjectClosure* const _is_alive;
4359   const bool               _unloading_occurred;
4360   const uint               _num_workers;
4361 
4362   // Variables used to claim nmethods.
4363   nmethod* _first_nmethod;
4364   volatile nmethod* _claimed_nmethod;
4365 
4366   // The list of nmethods that need to be processed by the second pass.
4367   volatile nmethod* _postponed_list;
4368   volatile uint     _num_entered_barrier;
4369 
4370  public:
4371   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4372       _is_alive(is_alive),
4373       _unloading_occurred(unloading_occurred),
4374       _num_workers(num_workers),
4375       _first_nmethod(NULL),
4376       _claimed_nmethod(NULL),
4377       _postponed_list(NULL),
4378       _num_entered_barrier(0)
4379   {
4380     nmethod::increase_unloading_clock();
4381     // Get first alive nmethod
4382     NMethodIterator iter = NMethodIterator();
4383     if(iter.next_alive()) {
4384       _first_nmethod = iter.method();
4385     }
4386     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4387   }
4388 
4389   ~G1CodeCacheUnloadingTask() {
4390     CodeCache::verify_clean_inline_caches();
4391 
4392     CodeCache::set_needs_cache_clean(false);
4393     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4394 
4395     CodeCache::verify_icholder_relocations();
4396   }
4397 
4398  private:
4399   void add_to_postponed_list(nmethod* nm) {
4400       nmethod* old;
4401       do {
4402         old = (nmethod*)_postponed_list;
4403         nm->set_unloading_next(old);
4404       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4405   }
4406 
4407   void clean_nmethod(nmethod* nm) {
4408     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4409 
4410     if (postponed) {
4411       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4412       add_to_postponed_list(nm);
4413     }
4414 
4415     // Mark that this thread has been cleaned/unloaded.
4416     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4417     nm->set_unloading_clock(nmethod::global_unloading_clock());
4418   }
4419 
4420   void clean_nmethod_postponed(nmethod* nm) {
4421     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4422   }
4423 
4424   static const int MaxClaimNmethods = 16;
4425 
4426   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4427     nmethod* first;
4428     NMethodIterator last;
4429 
4430     do {
4431       *num_claimed_nmethods = 0;
4432 
4433       first = (nmethod*)_claimed_nmethod;
4434       last = NMethodIterator(first);
4435 
4436       if (first != NULL) {
4437 
4438         for (int i = 0; i < MaxClaimNmethods; i++) {
4439           if (!last.next_alive()) {
4440             break;
4441           }
4442           claimed_nmethods[i] = last.method();
4443           (*num_claimed_nmethods)++;
4444         }
4445       }
4446 
4447     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4448   }
4449 
4450   nmethod* claim_postponed_nmethod() {
4451     nmethod* claim;
4452     nmethod* next;
4453 
4454     do {
4455       claim = (nmethod*)_postponed_list;
4456       if (claim == NULL) {
4457         return NULL;
4458       }
4459 
4460       next = claim->unloading_next();
4461 
4462     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4463 
4464     return claim;
4465   }
4466 
4467  public:
4468   // Mark that we're done with the first pass of nmethod cleaning.
4469   void barrier_mark(uint worker_id) {
4470     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4471     _num_entered_barrier++;
4472     if (_num_entered_barrier == _num_workers) {
4473       ml.notify_all();
4474     }
4475   }
4476 
4477   // See if we have to wait for the other workers to
4478   // finish their first-pass nmethod cleaning work.
4479   void barrier_wait(uint worker_id) {
4480     if (_num_entered_barrier < _num_workers) {
4481       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4482       while (_num_entered_barrier < _num_workers) {
4483           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4484       }
4485     }
4486   }
4487 
4488   // Cleaning and unloading of nmethods. Some work has to be postponed
4489   // to the second pass, when we know which nmethods survive.
4490   void work_first_pass(uint worker_id) {
4491     // The first nmethods is claimed by the first worker.
4492     if (worker_id == 0 && _first_nmethod != NULL) {
4493       clean_nmethod(_first_nmethod);
4494       _first_nmethod = NULL;
4495     }
4496 
4497     int num_claimed_nmethods;
4498     nmethod* claimed_nmethods[MaxClaimNmethods];
4499 
4500     while (true) {
4501       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4502 
4503       if (num_claimed_nmethods == 0) {
4504         break;
4505       }
4506 
4507       for (int i = 0; i < num_claimed_nmethods; i++) {
4508         clean_nmethod(claimed_nmethods[i]);
4509       }
4510     }
4511   }
4512 
4513   void work_second_pass(uint worker_id) {
4514     nmethod* nm;
4515     // Take care of postponed nmethods.
4516     while ((nm = claim_postponed_nmethod()) != NULL) {
4517       clean_nmethod_postponed(nm);
4518     }
4519   }
4520 };
4521 
4522 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4523 
4524 class G1KlassCleaningTask : public StackObj {
4525   BoolObjectClosure*                      _is_alive;
4526   volatile jint                           _clean_klass_tree_claimed;
4527   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4528 
4529  public:
4530   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4531       _is_alive(is_alive),
4532       _clean_klass_tree_claimed(0),
4533       _klass_iterator() {
4534   }
4535 
4536  private:
4537   bool claim_clean_klass_tree_task() {
4538     if (_clean_klass_tree_claimed) {
4539       return false;
4540     }
4541 
4542     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4543   }
4544 
4545   InstanceKlass* claim_next_klass() {
4546     Klass* klass;
4547     do {
4548       klass =_klass_iterator.next_klass();
4549     } while (klass != NULL && !klass->is_instance_klass());
4550 
4551     // this can be null so don't call InstanceKlass::cast
4552     return static_cast<InstanceKlass*>(klass);
4553   }
4554 
4555 public:
4556 
4557   void clean_klass(InstanceKlass* ik) {
4558     ik->clean_weak_instanceklass_links(_is_alive);
4559   }
4560 
4561   void work() {
4562     ResourceMark rm;
4563 
4564     // One worker will clean the subklass/sibling klass tree.
4565     if (claim_clean_klass_tree_task()) {
4566       Klass::clean_subklass_tree(_is_alive);
4567     }
4568 
4569     // All workers will help cleaning the classes,
4570     InstanceKlass* klass;
4571     while ((klass = claim_next_klass()) != NULL) {
4572       clean_klass(klass);
4573     }
4574   }
4575 };
4576 
4577 // To minimize the remark pause times, the tasks below are done in parallel.
4578 class G1ParallelCleaningTask : public AbstractGangTask {
4579 private:
4580   G1StringSymbolTableUnlinkTask _string_symbol_task;
4581   G1CodeCacheUnloadingTask      _code_cache_task;
4582   G1KlassCleaningTask           _klass_cleaning_task;
4583 
4584 public:
4585   // The constructor is run in the VMThread.
4586   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4587       AbstractGangTask("Parallel Cleaning"),
4588       _string_symbol_task(is_alive, process_strings, process_symbols),
4589       _code_cache_task(num_workers, is_alive, unloading_occurred),
4590       _klass_cleaning_task(is_alive) {
4591   }
4592 
4593   // The parallel work done by all worker threads.
4594   void work(uint worker_id) {
4595     // Do first pass of code cache cleaning.
4596     _code_cache_task.work_first_pass(worker_id);
4597 
4598     // Let the threads mark that the first pass is done.
4599     _code_cache_task.barrier_mark(worker_id);
4600 
4601     // Clean the Strings and Symbols.
4602     _string_symbol_task.work(worker_id);
4603 
4604     // Wait for all workers to finish the first code cache cleaning pass.
4605     _code_cache_task.barrier_wait(worker_id);
4606 
4607     // Do the second code cache cleaning work, which realize on
4608     // the liveness information gathered during the first pass.
4609     _code_cache_task.work_second_pass(worker_id);
4610 
4611     // Clean all klasses that were not unloaded.
4612     _klass_cleaning_task.work();
4613   }
4614 };
4615 
4616 
4617 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4618                                         bool process_strings,
4619                                         bool process_symbols,
4620                                         bool class_unloading_occurred) {
4621   uint n_workers = workers()->active_workers();
4622 
4623   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4624                                         n_workers, class_unloading_occurred);
4625   workers()->run_task(&g1_unlink_task);
4626 }
4627 
4628 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4629                                                      bool process_strings, bool process_symbols) {
4630   {
4631     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4632     workers()->run_task(&g1_unlink_task);
4633   }
4634 
4635   if (G1StringDedup::is_enabled()) {
4636     G1StringDedup::unlink(is_alive);
4637   }
4638 }
4639 
4640 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4641  private:
4642   DirtyCardQueueSet* _queue;
4643  public:
4644   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4645 
4646   virtual void work(uint worker_id) {
4647     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4648     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4649 
4650     RedirtyLoggedCardTableEntryClosure cl;
4651     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4652 
4653     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4654   }
4655 };
4656 
4657 void G1CollectedHeap::redirty_logged_cards() {
4658   double redirty_logged_cards_start = os::elapsedTime();
4659 
4660   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4661   dirty_card_queue_set().reset_for_par_iteration();
4662   workers()->run_task(&redirty_task);
4663 
4664   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4665   dcq.merge_bufferlists(&dirty_card_queue_set());
4666   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4667 
4668   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4669 }
4670 
4671 // Weak Reference Processing support
4672 
4673 // An always "is_alive" closure that is used to preserve referents.
4674 // If the object is non-null then it's alive.  Used in the preservation
4675 // of referent objects that are pointed to by reference objects
4676 // discovered by the CM ref processor.
4677 class G1AlwaysAliveClosure: public BoolObjectClosure {
4678   G1CollectedHeap* _g1;
4679 public:
4680   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4681   bool do_object_b(oop p) {
4682     if (p != NULL) {
4683       return true;
4684     }
4685     return false;
4686   }
4687 };
4688 
4689 bool G1STWIsAliveClosure::do_object_b(oop p) {
4690   // An object is reachable if it is outside the collection set,
4691   // or is inside and copied.
4692   return !_g1->is_in_cset(p) || p->is_forwarded();
4693 }
4694 
4695 // Non Copying Keep Alive closure
4696 class G1KeepAliveClosure: public OopClosure {
4697   G1CollectedHeap* _g1;
4698 public:
4699   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4700   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4701   void do_oop(oop* p) {
4702     oop obj = *p;
4703     assert(obj != NULL, "the caller should have filtered out NULL values");
4704 
4705     const InCSetState cset_state = _g1->in_cset_state(obj);
4706     if (!cset_state.is_in_cset_or_humongous()) {
4707       return;
4708     }
4709     if (cset_state.is_in_cset()) {
4710       assert( obj->is_forwarded(), "invariant" );
4711       *p = obj->forwardee();
4712     } else {
4713       assert(!obj->is_forwarded(), "invariant" );
4714       assert(cset_state.is_humongous(),
4715              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4716       _g1->set_humongous_is_live(obj);
4717     }
4718   }
4719 };
4720 
4721 // Copying Keep Alive closure - can be called from both
4722 // serial and parallel code as long as different worker
4723 // threads utilize different G1ParScanThreadState instances
4724 // and different queues.
4725 
4726 class G1CopyingKeepAliveClosure: public OopClosure {
4727   G1CollectedHeap*         _g1h;
4728   OopClosure*              _copy_non_heap_obj_cl;
4729   G1ParScanThreadState*    _par_scan_state;
4730 
4731 public:
4732   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4733                             OopClosure* non_heap_obj_cl,
4734                             G1ParScanThreadState* pss):
4735     _g1h(g1h),
4736     _copy_non_heap_obj_cl(non_heap_obj_cl),
4737     _par_scan_state(pss)
4738   {}
4739 
4740   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4741   virtual void do_oop(      oop* p) { do_oop_work(p); }
4742 
4743   template <class T> void do_oop_work(T* p) {
4744     oop obj = oopDesc::load_decode_heap_oop(p);
4745 
4746     if (_g1h->is_in_cset_or_humongous(obj)) {
4747       // If the referent object has been forwarded (either copied
4748       // to a new location or to itself in the event of an
4749       // evacuation failure) then we need to update the reference
4750       // field and, if both reference and referent are in the G1
4751       // heap, update the RSet for the referent.
4752       //
4753       // If the referent has not been forwarded then we have to keep
4754       // it alive by policy. Therefore we have copy the referent.
4755       //
4756       // If the reference field is in the G1 heap then we can push
4757       // on the PSS queue. When the queue is drained (after each
4758       // phase of reference processing) the object and it's followers
4759       // will be copied, the reference field set to point to the
4760       // new location, and the RSet updated. Otherwise we need to
4761       // use the the non-heap or metadata closures directly to copy
4762       // the referent object and update the pointer, while avoiding
4763       // updating the RSet.
4764 
4765       if (_g1h->is_in_g1_reserved(p)) {
4766         _par_scan_state->push_on_queue(p);
4767       } else {
4768         assert(!Metaspace::contains((const void*)p),
4769                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4770         _copy_non_heap_obj_cl->do_oop(p);
4771       }
4772     }
4773   }
4774 };
4775 
4776 // Serial drain queue closure. Called as the 'complete_gc'
4777 // closure for each discovered list in some of the
4778 // reference processing phases.
4779 
4780 class G1STWDrainQueueClosure: public VoidClosure {
4781 protected:
4782   G1CollectedHeap* _g1h;
4783   G1ParScanThreadState* _par_scan_state;
4784 
4785   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4786 
4787 public:
4788   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4789     _g1h(g1h),
4790     _par_scan_state(pss)
4791   { }
4792 
4793   void do_void() {
4794     G1ParScanThreadState* const pss = par_scan_state();
4795     pss->trim_queue();
4796   }
4797 };
4798 
4799 // Parallel Reference Processing closures
4800 
4801 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4802 // processing during G1 evacuation pauses.
4803 
4804 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4805 private:
4806   G1CollectedHeap*          _g1h;
4807   G1ParScanThreadStateSet*  _pss;
4808   RefToScanQueueSet*        _queues;
4809   WorkGang*                 _workers;
4810   uint                      _active_workers;
4811 
4812 public:
4813   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4814                            G1ParScanThreadStateSet* per_thread_states,
4815                            WorkGang* workers,
4816                            RefToScanQueueSet *task_queues,
4817                            uint n_workers) :
4818     _g1h(g1h),
4819     _pss(per_thread_states),
4820     _queues(task_queues),
4821     _workers(workers),
4822     _active_workers(n_workers)
4823   {
4824     assert(n_workers > 0, "shouldn't call this otherwise");
4825   }
4826 
4827   // Executes the given task using concurrent marking worker threads.
4828   virtual void execute(ProcessTask& task);
4829   virtual void execute(EnqueueTask& task);
4830 };
4831 
4832 // Gang task for possibly parallel reference processing
4833 
4834 class G1STWRefProcTaskProxy: public AbstractGangTask {
4835   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4836   ProcessTask&     _proc_task;
4837   G1CollectedHeap* _g1h;
4838   G1ParScanThreadStateSet* _pss;
4839   RefToScanQueueSet* _task_queues;
4840   ParallelTaskTerminator* _terminator;
4841 
4842 public:
4843   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4844                         G1CollectedHeap* g1h,
4845                         G1ParScanThreadStateSet* per_thread_states,
4846                         RefToScanQueueSet *task_queues,
4847                         ParallelTaskTerminator* terminator) :
4848     AbstractGangTask("Process reference objects in parallel"),
4849     _proc_task(proc_task),
4850     _g1h(g1h),
4851     _pss(per_thread_states),
4852     _task_queues(task_queues),
4853     _terminator(terminator)
4854   {}
4855 
4856   virtual void work(uint worker_id) {
4857     // The reference processing task executed by a single worker.
4858     ResourceMark rm;
4859     HandleMark   hm;
4860 
4861     G1STWIsAliveClosure is_alive(_g1h);
4862 
4863     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4864     pss->set_ref_processor(NULL);
4865 
4866     // Keep alive closure.
4867     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4868 
4869     // Complete GC closure
4870     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4871 
4872     // Call the reference processing task's work routine.
4873     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4874 
4875     // Note we cannot assert that the refs array is empty here as not all
4876     // of the processing tasks (specifically phase2 - pp2_work) execute
4877     // the complete_gc closure (which ordinarily would drain the queue) so
4878     // the queue may not be empty.
4879   }
4880 };
4881 
4882 // Driver routine for parallel reference processing.
4883 // Creates an instance of the ref processing gang
4884 // task and has the worker threads execute it.
4885 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4886   assert(_workers != NULL, "Need parallel worker threads.");
4887 
4888   ParallelTaskTerminator terminator(_active_workers, _queues);
4889   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4890 
4891   _workers->run_task(&proc_task_proxy);
4892 }
4893 
4894 // Gang task for parallel reference enqueueing.
4895 
4896 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4897   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4898   EnqueueTask& _enq_task;
4899 
4900 public:
4901   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4902     AbstractGangTask("Enqueue reference objects in parallel"),
4903     _enq_task(enq_task)
4904   { }
4905 
4906   virtual void work(uint worker_id) {
4907     _enq_task.work(worker_id);
4908   }
4909 };
4910 
4911 // Driver routine for parallel reference enqueueing.
4912 // Creates an instance of the ref enqueueing gang
4913 // task and has the worker threads execute it.
4914 
4915 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4916   assert(_workers != NULL, "Need parallel worker threads.");
4917 
4918   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4919 
4920   _workers->run_task(&enq_task_proxy);
4921 }
4922 
4923 // End of weak reference support closures
4924 
4925 // Abstract task used to preserve (i.e. copy) any referent objects
4926 // that are in the collection set and are pointed to by reference
4927 // objects discovered by the CM ref processor.
4928 
4929 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4930 protected:
4931   G1CollectedHeap*         _g1h;
4932   G1ParScanThreadStateSet* _pss;
4933   RefToScanQueueSet*       _queues;
4934   ParallelTaskTerminator   _terminator;
4935   uint                     _n_workers;
4936 
4937 public:
4938   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4939     AbstractGangTask("ParPreserveCMReferents"),
4940     _g1h(g1h),
4941     _pss(per_thread_states),
4942     _queues(task_queues),
4943     _terminator(workers, _queues),
4944     _n_workers(workers)
4945   { }
4946 
4947   void work(uint worker_id) {
4948     ResourceMark rm;
4949     HandleMark   hm;
4950 
4951     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4952     pss->set_ref_processor(NULL);
4953     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4954 
4955     // Is alive closure
4956     G1AlwaysAliveClosure always_alive(_g1h);
4957 
4958     // Copying keep alive closure. Applied to referent objects that need
4959     // to be copied.
4960     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4961 
4962     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4963 
4964     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4965     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4966 
4967     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4968     // So this must be true - but assert just in case someone decides to
4969     // change the worker ids.
4970     assert(worker_id < limit, "sanity");
4971     assert(!rp->discovery_is_atomic(), "check this code");
4972 
4973     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4974     for (uint idx = worker_id; idx < limit; idx += stride) {
4975       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4976 
4977       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4978       while (iter.has_next()) {
4979         // Since discovery is not atomic for the CM ref processor, we
4980         // can see some null referent objects.
4981         iter.load_ptrs(DEBUG_ONLY(true));
4982         oop ref = iter.obj();
4983 
4984         // This will filter nulls.
4985         if (iter.is_referent_alive()) {
4986           iter.make_referent_alive();
4987         }
4988         iter.move_to_next();
4989       }
4990     }
4991 
4992     // Drain the queue - which may cause stealing
4993     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4994     drain_queue.do_void();
4995     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4996     assert(pss->queue_is_empty(), "should be");
4997   }
4998 };
4999 
5000 // Weak Reference processing during an evacuation pause (part 1).
5001 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5002   double ref_proc_start = os::elapsedTime();
5003 
5004   ReferenceProcessor* rp = _ref_processor_stw;
5005   assert(rp->discovery_enabled(), "should have been enabled");
5006 
5007   // Any reference objects, in the collection set, that were 'discovered'
5008   // by the CM ref processor should have already been copied (either by
5009   // applying the external root copy closure to the discovered lists, or
5010   // by following an RSet entry).
5011   //
5012   // But some of the referents, that are in the collection set, that these
5013   // reference objects point to may not have been copied: the STW ref
5014   // processor would have seen that the reference object had already
5015   // been 'discovered' and would have skipped discovering the reference,
5016   // but would not have treated the reference object as a regular oop.
5017   // As a result the copy closure would not have been applied to the
5018   // referent object.
5019   //
5020   // We need to explicitly copy these referent objects - the references
5021   // will be processed at the end of remarking.
5022   //
5023   // We also need to do this copying before we process the reference
5024   // objects discovered by the STW ref processor in case one of these
5025   // referents points to another object which is also referenced by an
5026   // object discovered by the STW ref processor.
5027 
5028   uint no_of_gc_workers = workers()->active_workers();
5029 
5030   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5031                                                  per_thread_states,
5032                                                  no_of_gc_workers,
5033                                                  _task_queues);
5034 
5035   workers()->run_task(&keep_cm_referents);
5036 
5037   // Closure to test whether a referent is alive.
5038   G1STWIsAliveClosure is_alive(this);
5039 
5040   // Even when parallel reference processing is enabled, the processing
5041   // of JNI refs is serial and performed serially by the current thread
5042   // rather than by a worker. The following PSS will be used for processing
5043   // JNI refs.
5044 
5045   // Use only a single queue for this PSS.
5046   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
5047   pss->set_ref_processor(NULL);
5048   assert(pss->queue_is_empty(), "pre-condition");
5049 
5050   // Keep alive closure.
5051   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5052 
5053   // Serial Complete GC closure
5054   G1STWDrainQueueClosure drain_queue(this, pss);
5055 
5056   // Setup the soft refs policy...
5057   rp->setup_policy(false);
5058 
5059   ReferenceProcessorStats stats;
5060   if (!rp->processing_is_mt()) {
5061     // Serial reference processing...
5062     stats = rp->process_discovered_references(&is_alive,
5063                                               &keep_alive,
5064                                               &drain_queue,
5065                                               NULL,
5066                                               _gc_timer_stw);
5067   } else {
5068     // Parallel reference processing
5069     assert(rp->num_q() == no_of_gc_workers, "sanity");
5070     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5071 
5072     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5073     stats = rp->process_discovered_references(&is_alive,
5074                                               &keep_alive,
5075                                               &drain_queue,
5076                                               &par_task_executor,
5077                                               _gc_timer_stw);
5078   }
5079 
5080   _gc_tracer_stw->report_gc_reference_stats(stats);
5081 
5082   // We have completed copying any necessary live referent objects.
5083   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5084 
5085   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5086   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5087 }
5088 
5089 // Weak Reference processing during an evacuation pause (part 2).
5090 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5091   double ref_enq_start = os::elapsedTime();
5092 
5093   ReferenceProcessor* rp = _ref_processor_stw;
5094   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5095 
5096   // Now enqueue any remaining on the discovered lists on to
5097   // the pending list.
5098   if (!rp->processing_is_mt()) {
5099     // Serial reference processing...
5100     rp->enqueue_discovered_references();
5101   } else {
5102     // Parallel reference enqueueing
5103 
5104     uint n_workers = workers()->active_workers();
5105 
5106     assert(rp->num_q() == n_workers, "sanity");
5107     assert(n_workers <= rp->max_num_q(), "sanity");
5108 
5109     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5110     rp->enqueue_discovered_references(&par_task_executor);
5111   }
5112 
5113   rp->verify_no_references_recorded();
5114   assert(!rp->discovery_enabled(), "should have been disabled");
5115 
5116   // FIXME
5117   // CM's reference processing also cleans up the string and symbol tables.
5118   // Should we do that here also? We could, but it is a serial operation
5119   // and could significantly increase the pause time.
5120 
5121   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5122   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5123 }
5124 
5125 void G1CollectedHeap::pre_evacuate_collection_set() {
5126   _expand_heap_after_alloc_failure = true;
5127   _evacuation_failed = false;
5128 
5129   // Disable the hot card cache.
5130   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5131   hot_card_cache->reset_hot_cache_claimed_index();
5132   hot_card_cache->set_use_cache(false);
5133 
5134 }
5135 
5136 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5137   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5138 
5139   // Should G1EvacuationFailureALot be in effect for this GC?
5140   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5141 
5142   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5143   double start_par_time_sec = os::elapsedTime();
5144   double end_par_time_sec;
5145 
5146   {
5147     const uint n_workers = workers()->active_workers();
5148     G1RootProcessor root_processor(this, n_workers);
5149     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5150     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5151     if (collector_state()->during_initial_mark_pause()) {
5152       ClassLoaderDataGraph::clear_claimed_marks();
5153     }
5154 
5155     // The individual threads will set their evac-failure closures.
5156     if (PrintTerminationStats) {
5157       print_termination_stats_hdr(gclog_or_tty);
5158     }
5159 
5160     workers()->run_task(&g1_par_task);
5161     end_par_time_sec = os::elapsedTime();
5162 
5163     // Closing the inner scope will execute the destructor
5164     // for the G1RootProcessor object. We record the current
5165     // elapsed time before closing the scope so that time
5166     // taken for the destructor is NOT included in the
5167     // reported parallel time.
5168   }
5169 
5170   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5171 
5172   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5173   phase_times->record_par_time(par_time_ms);
5174 
5175   double code_root_fixup_time_ms =
5176         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5177   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5178 
5179   // Process any discovered reference objects - we have
5180   // to do this _before_ we retire the GC alloc regions
5181   // as we may have to copy some 'reachable' referent
5182   // objects (and their reachable sub-graphs) that were
5183   // not copied during the pause.
5184   process_discovered_references(per_thread_states);
5185 
5186   if (G1StringDedup::is_enabled()) {
5187     double fixup_start = os::elapsedTime();
5188 
5189     G1STWIsAliveClosure is_alive(this);
5190     G1KeepAliveClosure keep_alive(this);
5191     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5192 
5193     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5194     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5195   }
5196 
5197   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5198 
5199   if (evacuation_failed()) {
5200     remove_self_forwarding_pointers();
5201 
5202     // Reset the G1EvacuationFailureALot counters and flags
5203     // Note: the values are reset only when an actual
5204     // evacuation failure occurs.
5205     NOT_PRODUCT(reset_evacuation_should_fail();)
5206   }
5207 
5208   // Enqueue any remaining references remaining on the STW
5209   // reference processor's discovered lists. We need to do
5210   // this after the card table is cleaned (and verified) as
5211   // the act of enqueueing entries on to the pending list
5212   // will log these updates (and dirty their associated
5213   // cards). We need these updates logged to update any
5214   // RSets.
5215   enqueue_discovered_references(per_thread_states);
5216 }
5217 
5218 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5219   _allocator->release_gc_alloc_regions(evacuation_info);
5220 
5221   per_thread_states->flush();
5222 
5223   record_obj_copy_mem_stats();
5224 
5225   _survivor_evac_stats.adjust_desired_plab_sz();
5226   _old_evac_stats.adjust_desired_plab_sz();
5227 
5228   // Reset and re-enable the hot card cache.
5229   // Note the counts for the cards in the regions in the
5230   // collection set are reset when the collection set is freed.
5231   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5232   hot_card_cache->reset_hot_cache();
5233   hot_card_cache->set_use_cache(true);
5234 
5235   purge_code_root_memory();
5236 
5237   redirty_logged_cards();
5238 #if defined(COMPILER2) || INCLUDE_JVMCI
5239   DerivedPointerTable::update_pointers();
5240 #endif
5241 }
5242 
5243 void G1CollectedHeap::record_obj_copy_mem_stats() {
5244   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5245 
5246   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5247                                                create_g1_evac_summary(&_old_evac_stats));
5248 }
5249 
5250 void G1CollectedHeap::free_region(HeapRegion* hr,
5251                                   FreeRegionList* free_list,
5252                                   bool par,
5253                                   bool locked) {
5254   assert(!hr->is_free(), "the region should not be free");
5255   assert(!hr->is_empty(), "the region should not be empty");
5256   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5257   assert(free_list != NULL, "pre-condition");
5258 
5259   if (G1VerifyBitmaps) {
5260     MemRegion mr(hr->bottom(), hr->end());
5261     concurrent_mark()->clearRangePrevBitmap(mr);
5262   }
5263 
5264   // Clear the card counts for this region.
5265   // Note: we only need to do this if the region is not young
5266   // (since we don't refine cards in young regions).
5267   if (!hr->is_young()) {
5268     _cg1r->hot_card_cache()->reset_card_counts(hr);
5269   }
5270   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5271   free_list->add_ordered(hr);
5272 }
5273 
5274 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5275                                             FreeRegionList* free_list,
5276                                             bool par) {
5277   assert(hr->is_humongous(), "this is only for humongous regions");
5278   assert(free_list != NULL, "pre-condition");
5279   hr->clear_humongous();
5280   free_region(hr, free_list, par);
5281 }
5282 
5283 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5284                                            const HeapRegionSetCount& humongous_regions_removed) {
5285   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5286     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5287     _old_set.bulk_remove(old_regions_removed);
5288     _humongous_set.bulk_remove(humongous_regions_removed);
5289   }
5290 
5291 }
5292 
5293 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5294   assert(list != NULL, "list can't be null");
5295   if (!list->is_empty()) {
5296     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5297     _hrm.insert_list_into_free_list(list);
5298   }
5299 }
5300 
5301 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5302   decrease_used(bytes);
5303 }
5304 
5305 class G1ParCleanupCTTask : public AbstractGangTask {
5306   G1SATBCardTableModRefBS* _ct_bs;
5307   G1CollectedHeap* _g1h;
5308   HeapRegion* volatile _su_head;
5309 public:
5310   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5311                      G1CollectedHeap* g1h) :
5312     AbstractGangTask("G1 Par Cleanup CT Task"),
5313     _ct_bs(ct_bs), _g1h(g1h) { }
5314 
5315   void work(uint worker_id) {
5316     HeapRegion* r;
5317     while (r = _g1h->pop_dirty_cards_region()) {
5318       clear_cards(r);
5319     }
5320   }
5321 
5322   void clear_cards(HeapRegion* r) {
5323     // Cards of the survivors should have already been dirtied.
5324     if (!r->is_survivor()) {
5325       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5326     }
5327   }
5328 };
5329 
5330 #ifndef PRODUCT
5331 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5332   G1CollectedHeap* _g1h;
5333   G1SATBCardTableModRefBS* _ct_bs;
5334 public:
5335   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5336     : _g1h(g1h), _ct_bs(ct_bs) { }
5337   virtual bool doHeapRegion(HeapRegion* r) {
5338     if (r->is_survivor()) {
5339       _g1h->verify_dirty_region(r);
5340     } else {
5341       _g1h->verify_not_dirty_region(r);
5342     }
5343     return false;
5344   }
5345 };
5346 
5347 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5348   // All of the region should be clean.
5349   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5350   MemRegion mr(hr->bottom(), hr->end());
5351   ct_bs->verify_not_dirty_region(mr);
5352 }
5353 
5354 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5355   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5356   // dirty allocated blocks as they allocate them. The thread that
5357   // retires each region and replaces it with a new one will do a
5358   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5359   // not dirty that area (one less thing to have to do while holding
5360   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5361   // is dirty.
5362   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5363   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5364   if (hr->is_young()) {
5365     ct_bs->verify_g1_young_region(mr);
5366   } else {
5367     ct_bs->verify_dirty_region(mr);
5368   }
5369 }
5370 
5371 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5372   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5373   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5374     verify_dirty_region(hr);
5375   }
5376 }
5377 
5378 void G1CollectedHeap::verify_dirty_young_regions() {
5379   verify_dirty_young_list(_young_list->first_region());
5380 }
5381 
5382 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5383                                                HeapWord* tams, HeapWord* end) {
5384   guarantee(tams <= end,
5385             "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5386   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5387   if (result < end) {
5388     gclog_or_tty->cr();
5389     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5390                            bitmap_name, p2i(result));
5391     gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5392                            bitmap_name, p2i(tams), p2i(end));
5393     return false;
5394   }
5395   return true;
5396 }
5397 
5398 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5399   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5400   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5401 
5402   HeapWord* bottom = hr->bottom();
5403   HeapWord* ptams  = hr->prev_top_at_mark_start();
5404   HeapWord* ntams  = hr->next_top_at_mark_start();
5405   HeapWord* end    = hr->end();
5406 
5407   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5408 
5409   bool res_n = true;
5410   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5411   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5412   // if we happen to be in that state.
5413   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5414     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5415   }
5416   if (!res_p || !res_n) {
5417     gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5418                            HR_FORMAT_PARAMS(hr));
5419     gclog_or_tty->print_cr("#### Caller: %s", caller);
5420     return false;
5421   }
5422   return true;
5423 }
5424 
5425 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5426   if (!G1VerifyBitmaps) return;
5427 
5428   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5429 }
5430 
5431 class G1VerifyBitmapClosure : public HeapRegionClosure {
5432 private:
5433   const char* _caller;
5434   G1CollectedHeap* _g1h;
5435   bool _failures;
5436 
5437 public:
5438   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5439     _caller(caller), _g1h(g1h), _failures(false) { }
5440 
5441   bool failures() { return _failures; }
5442 
5443   virtual bool doHeapRegion(HeapRegion* hr) {
5444     bool result = _g1h->verify_bitmaps(_caller, hr);
5445     if (!result) {
5446       _failures = true;
5447     }
5448     return false;
5449   }
5450 };
5451 
5452 void G1CollectedHeap::check_bitmaps(const char* caller) {
5453   if (!G1VerifyBitmaps) return;
5454 
5455   G1VerifyBitmapClosure cl(caller, this);
5456   heap_region_iterate(&cl);
5457   guarantee(!cl.failures(), "bitmap verification");
5458 }
5459 
5460 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5461  private:
5462   bool _failures;
5463  public:
5464   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5465 
5466   virtual bool doHeapRegion(HeapRegion* hr) {
5467     uint i = hr->hrm_index();
5468     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5469     if (hr->is_humongous()) {
5470       if (hr->in_collection_set()) {
5471         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5472         _failures = true;
5473         return true;
5474       }
5475       if (cset_state.is_in_cset()) {
5476         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5477         _failures = true;
5478         return true;
5479       }
5480       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5481         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5482         _failures = true;
5483         return true;
5484       }
5485     } else {
5486       if (cset_state.is_humongous()) {
5487         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5488         _failures = true;
5489         return true;
5490       }
5491       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5492         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5493                                hr->in_collection_set(), cset_state.value(), i);
5494         _failures = true;
5495         return true;
5496       }
5497       if (cset_state.is_in_cset()) {
5498         if (hr->is_young() != (cset_state.is_young())) {
5499           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5500                                  hr->is_young(), cset_state.value(), i);
5501           _failures = true;
5502           return true;
5503         }
5504         if (hr->is_old() != (cset_state.is_old())) {
5505           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5506                                  hr->is_old(), cset_state.value(), i);
5507           _failures = true;
5508           return true;
5509         }
5510       }
5511     }
5512     return false;
5513   }
5514 
5515   bool failures() const { return _failures; }
5516 };
5517 
5518 bool G1CollectedHeap::check_cset_fast_test() {
5519   G1CheckCSetFastTableClosure cl;
5520   _hrm.iterate(&cl);
5521   return !cl.failures();
5522 }
5523 #endif // PRODUCT
5524 
5525 void G1CollectedHeap::cleanUpCardTable() {
5526   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5527   double start = os::elapsedTime();
5528 
5529   {
5530     // Iterate over the dirty cards region list.
5531     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5532 
5533     workers()->run_task(&cleanup_task);
5534 #ifndef PRODUCT
5535     if (G1VerifyCTCleanup || VerifyAfterGC) {
5536       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5537       heap_region_iterate(&cleanup_verifier);
5538     }
5539 #endif
5540   }
5541 
5542   double elapsed = os::elapsedTime() - start;
5543   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5544 }
5545 
5546 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5547   size_t pre_used = 0;
5548   FreeRegionList local_free_list("Local List for CSet Freeing");
5549 
5550   double young_time_ms     = 0.0;
5551   double non_young_time_ms = 0.0;
5552 
5553   // Since the collection set is a superset of the the young list,
5554   // all we need to do to clear the young list is clear its
5555   // head and length, and unlink any young regions in the code below
5556   _young_list->clear();
5557 
5558   G1CollectorPolicy* policy = g1_policy();
5559 
5560   double start_sec = os::elapsedTime();
5561   bool non_young = true;
5562 
5563   HeapRegion* cur = cs_head;
5564   int age_bound = -1;
5565   size_t rs_lengths = 0;
5566 
5567   while (cur != NULL) {
5568     assert(!is_on_master_free_list(cur), "sanity");
5569     if (non_young) {
5570       if (cur->is_young()) {
5571         double end_sec = os::elapsedTime();
5572         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5573         non_young_time_ms += elapsed_ms;
5574 
5575         start_sec = os::elapsedTime();
5576         non_young = false;
5577       }
5578     } else {
5579       if (!cur->is_young()) {
5580         double end_sec = os::elapsedTime();
5581         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5582         young_time_ms += elapsed_ms;
5583 
5584         start_sec = os::elapsedTime();
5585         non_young = true;
5586       }
5587     }
5588 
5589     rs_lengths += cur->rem_set()->occupied_locked();
5590 
5591     HeapRegion* next = cur->next_in_collection_set();
5592     assert(cur->in_collection_set(), "bad CS");
5593     cur->set_next_in_collection_set(NULL);
5594     clear_in_cset(cur);
5595 
5596     if (cur->is_young()) {
5597       int index = cur->young_index_in_cset();
5598       assert(index != -1, "invariant");
5599       assert((uint) index < policy->young_cset_region_length(), "invariant");
5600       size_t words_survived = surviving_young_words[index];
5601       cur->record_surv_words_in_group(words_survived);
5602 
5603       // At this point the we have 'popped' cur from the collection set
5604       // (linked via next_in_collection_set()) but it is still in the
5605       // young list (linked via next_young_region()). Clear the
5606       // _next_young_region field.
5607       cur->set_next_young_region(NULL);
5608     } else {
5609       int index = cur->young_index_in_cset();
5610       assert(index == -1, "invariant");
5611     }
5612 
5613     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5614             (!cur->is_young() && cur->young_index_in_cset() == -1),
5615             "invariant" );
5616 
5617     if (!cur->evacuation_failed()) {
5618       MemRegion used_mr = cur->used_region();
5619 
5620       // And the region is empty.
5621       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5622       pre_used += cur->used();
5623       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5624     } else {
5625       cur->uninstall_surv_rate_group();
5626       if (cur->is_young()) {
5627         cur->set_young_index_in_cset(-1);
5628       }
5629       cur->set_evacuation_failed(false);
5630       // When moving a young gen region to old gen, we "allocate" that whole region
5631       // there. This is in addition to any already evacuated objects. Notify the
5632       // policy about that.
5633       // Old gen regions do not cause an additional allocation: both the objects
5634       // still in the region and the ones already moved are accounted for elsewhere.
5635       if (cur->is_young()) {
5636         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5637       }
5638       // The region is now considered to be old.
5639       cur->set_old();
5640       // Do some allocation statistics accounting. Regions that failed evacuation
5641       // are always made old, so there is no need to update anything in the young
5642       // gen statistics, but we need to update old gen statistics.
5643       size_t used_words = cur->marked_bytes() / HeapWordSize;
5644       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5645       _old_set.add(cur);
5646       evacuation_info.increment_collectionset_used_after(cur->used());
5647     }
5648     cur = next;
5649   }
5650 
5651   evacuation_info.set_regions_freed(local_free_list.length());
5652   policy->record_max_rs_lengths(rs_lengths);
5653   policy->cset_regions_freed();
5654 
5655   double end_sec = os::elapsedTime();
5656   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5657 
5658   if (non_young) {
5659     non_young_time_ms += elapsed_ms;
5660   } else {
5661     young_time_ms += elapsed_ms;
5662   }
5663 
5664   prepend_to_freelist(&local_free_list);
5665   decrement_summary_bytes(pre_used);
5666   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5667   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5668 }
5669 
5670 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5671  private:
5672   FreeRegionList* _free_region_list;
5673   HeapRegionSet* _proxy_set;
5674   HeapRegionSetCount _humongous_regions_removed;
5675   size_t _freed_bytes;
5676  public:
5677 
5678   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5679     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5680   }
5681 
5682   virtual bool doHeapRegion(HeapRegion* r) {
5683     if (!r->is_starts_humongous()) {
5684       return false;
5685     }
5686 
5687     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5688 
5689     oop obj = (oop)r->bottom();
5690     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5691 
5692     // The following checks whether the humongous object is live are sufficient.
5693     // The main additional check (in addition to having a reference from the roots
5694     // or the young gen) is whether the humongous object has a remembered set entry.
5695     //
5696     // A humongous object cannot be live if there is no remembered set for it
5697     // because:
5698     // - there can be no references from within humongous starts regions referencing
5699     // the object because we never allocate other objects into them.
5700     // (I.e. there are no intra-region references that may be missed by the
5701     // remembered set)
5702     // - as soon there is a remembered set entry to the humongous starts region
5703     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5704     // until the end of a concurrent mark.
5705     //
5706     // It is not required to check whether the object has been found dead by marking
5707     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5708     // all objects allocated during that time are considered live.
5709     // SATB marking is even more conservative than the remembered set.
5710     // So if at this point in the collection there is no remembered set entry,
5711     // nobody has a reference to it.
5712     // At the start of collection we flush all refinement logs, and remembered sets
5713     // are completely up-to-date wrt to references to the humongous object.
5714     //
5715     // Other implementation considerations:
5716     // - never consider object arrays at this time because they would pose
5717     // considerable effort for cleaning up the the remembered sets. This is
5718     // required because stale remembered sets might reference locations that
5719     // are currently allocated into.
5720     uint region_idx = r->hrm_index();
5721     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5722         !r->rem_set()->is_empty()) {
5723 
5724       if (G1TraceEagerReclaimHumongousObjects) {
5725         gclog_or_tty->print_cr("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",
5726                                region_idx,
5727                                (size_t)obj->size() * HeapWordSize,
5728                                p2i(r->bottom()),
5729                                r->rem_set()->occupied(),
5730                                r->rem_set()->strong_code_roots_list_length(),
5731                                next_bitmap->isMarked(r->bottom()),
5732                                g1h->is_humongous_reclaim_candidate(region_idx),
5733                                obj->is_typeArray()
5734                               );
5735       }
5736 
5737       return false;
5738     }
5739 
5740     guarantee(obj->is_typeArray(),
5741               "Only eagerly reclaiming type arrays is supported, but the object "
5742               PTR_FORMAT " is not.", p2i(r->bottom()));
5743 
5744     if (G1TraceEagerReclaimHumongousObjects) {
5745       gclog_or_tty->print_cr("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",
5746                              region_idx,
5747                              (size_t)obj->size() * HeapWordSize,
5748                              p2i(r->bottom()),
5749                              r->rem_set()->occupied(),
5750                              r->rem_set()->strong_code_roots_list_length(),
5751                              next_bitmap->isMarked(r->bottom()),
5752                              g1h->is_humongous_reclaim_candidate(region_idx),
5753                              obj->is_typeArray()
5754                             );
5755     }
5756     // Need to clear mark bit of the humongous object if already set.
5757     if (next_bitmap->isMarked(r->bottom())) {
5758       next_bitmap->clear(r->bottom());
5759     }
5760     do {
5761       HeapRegion* next = g1h->next_region_in_humongous(r);
5762       _freed_bytes += r->used();
5763       r->set_containing_set(NULL);
5764       _humongous_regions_removed.increment(1u, r->capacity());
5765       g1h->free_humongous_region(r, _free_region_list, false);
5766       r = next;
5767     } while (r != NULL);
5768 
5769     return false;
5770   }
5771 
5772   HeapRegionSetCount& humongous_free_count() {
5773     return _humongous_regions_removed;
5774   }
5775 
5776   size_t bytes_freed() const {
5777     return _freed_bytes;
5778   }
5779 
5780   size_t humongous_reclaimed() const {
5781     return _humongous_regions_removed.length();
5782   }
5783 };
5784 
5785 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5786   assert_at_safepoint(true);
5787 
5788   if (!G1EagerReclaimHumongousObjects ||
5789       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5790     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5791     return;
5792   }
5793 
5794   double start_time = os::elapsedTime();
5795 
5796   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5797 
5798   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5799   heap_region_iterate(&cl);
5800 
5801   HeapRegionSetCount empty_set;
5802   remove_from_old_sets(empty_set, cl.humongous_free_count());
5803 
5804   G1HRPrinter* hrp = hr_printer();
5805   if (hrp->is_active()) {
5806     FreeRegionListIterator iter(&local_cleanup_list);
5807     while (iter.more_available()) {
5808       HeapRegion* hr = iter.get_next();
5809       hrp->cleanup(hr);
5810     }
5811   }
5812 
5813   prepend_to_freelist(&local_cleanup_list);
5814   decrement_summary_bytes(cl.bytes_freed());
5815 
5816   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5817                                                                     cl.humongous_reclaimed());
5818 }
5819 
5820 // This routine is similar to the above but does not record
5821 // any policy statistics or update free lists; we are abandoning
5822 // the current incremental collection set in preparation of a
5823 // full collection. After the full GC we will start to build up
5824 // the incremental collection set again.
5825 // This is only called when we're doing a full collection
5826 // and is immediately followed by the tearing down of the young list.
5827 
5828 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5829   HeapRegion* cur = cs_head;
5830 
5831   while (cur != NULL) {
5832     HeapRegion* next = cur->next_in_collection_set();
5833     assert(cur->in_collection_set(), "bad CS");
5834     cur->set_next_in_collection_set(NULL);
5835     clear_in_cset(cur);
5836     cur->set_young_index_in_cset(-1);
5837     cur = next;
5838   }
5839 }
5840 
5841 void G1CollectedHeap::set_free_regions_coming() {
5842   if (G1ConcRegionFreeingVerbose) {
5843     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5844                            "setting free regions coming");
5845   }
5846 
5847   assert(!free_regions_coming(), "pre-condition");
5848   _free_regions_coming = true;
5849 }
5850 
5851 void G1CollectedHeap::reset_free_regions_coming() {
5852   assert(free_regions_coming(), "pre-condition");
5853 
5854   {
5855     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5856     _free_regions_coming = false;
5857     SecondaryFreeList_lock->notify_all();
5858   }
5859 
5860   if (G1ConcRegionFreeingVerbose) {
5861     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5862                            "reset free regions coming");
5863   }
5864 }
5865 
5866 void G1CollectedHeap::wait_while_free_regions_coming() {
5867   // Most of the time we won't have to wait, so let's do a quick test
5868   // first before we take the lock.
5869   if (!free_regions_coming()) {
5870     return;
5871   }
5872 
5873   if (G1ConcRegionFreeingVerbose) {
5874     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5875                            "waiting for free regions");
5876   }
5877 
5878   {
5879     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5880     while (free_regions_coming()) {
5881       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5882     }
5883   }
5884 
5885   if (G1ConcRegionFreeingVerbose) {
5886     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5887                            "done waiting for free regions");
5888   }
5889 }
5890 
5891 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5892   return _allocator->is_retained_old_region(hr);
5893 }
5894 
5895 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5896   _young_list->push_region(hr);
5897 }
5898 
5899 class NoYoungRegionsClosure: public HeapRegionClosure {
5900 private:
5901   bool _success;
5902 public:
5903   NoYoungRegionsClosure() : _success(true) { }
5904   bool doHeapRegion(HeapRegion* r) {
5905     if (r->is_young()) {
5906       gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5907                              p2i(r->bottom()), p2i(r->end()));
5908       _success = false;
5909     }
5910     return false;
5911   }
5912   bool success() { return _success; }
5913 };
5914 
5915 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5916   bool ret = _young_list->check_list_empty(check_sample);
5917 
5918   if (check_heap) {
5919     NoYoungRegionsClosure closure;
5920     heap_region_iterate(&closure);
5921     ret = ret && closure.success();
5922   }
5923 
5924   return ret;
5925 }
5926 
5927 class TearDownRegionSetsClosure : public HeapRegionClosure {
5928 private:
5929   HeapRegionSet *_old_set;
5930 
5931 public:
5932   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5933 
5934   bool doHeapRegion(HeapRegion* r) {
5935     if (r->is_old()) {
5936       _old_set->remove(r);
5937     } else {
5938       // We ignore free regions, we'll empty the free list afterwards.
5939       // We ignore young regions, we'll empty the young list afterwards.
5940       // We ignore humongous regions, we're not tearing down the
5941       // humongous regions set.
5942       assert(r->is_free() || r->is_young() || r->is_humongous(),
5943              "it cannot be another type");
5944     }
5945     return false;
5946   }
5947 
5948   ~TearDownRegionSetsClosure() {
5949     assert(_old_set->is_empty(), "post-condition");
5950   }
5951 };
5952 
5953 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5954   assert_at_safepoint(true /* should_be_vm_thread */);
5955 
5956   if (!free_list_only) {
5957     TearDownRegionSetsClosure cl(&_old_set);
5958     heap_region_iterate(&cl);
5959 
5960     // Note that emptying the _young_list is postponed and instead done as
5961     // the first step when rebuilding the regions sets again. The reason for
5962     // this is that during a full GC string deduplication needs to know if
5963     // a collected region was young or old when the full GC was initiated.
5964   }
5965   _hrm.remove_all_free_regions();
5966 }
5967 
5968 void G1CollectedHeap::increase_used(size_t bytes) {
5969   _summary_bytes_used += bytes;
5970 }
5971 
5972 void G1CollectedHeap::decrease_used(size_t bytes) {
5973   assert(_summary_bytes_used >= bytes,
5974          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5975          _summary_bytes_used, bytes);
5976   _summary_bytes_used -= bytes;
5977 }
5978 
5979 void G1CollectedHeap::set_used(size_t bytes) {
5980   _summary_bytes_used = bytes;
5981 }
5982 
5983 class RebuildRegionSetsClosure : public HeapRegionClosure {
5984 private:
5985   bool            _free_list_only;
5986   HeapRegionSet*   _old_set;
5987   HeapRegionManager*   _hrm;
5988   size_t          _total_used;
5989 
5990 public:
5991   RebuildRegionSetsClosure(bool free_list_only,
5992                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5993     _free_list_only(free_list_only),
5994     _old_set(old_set), _hrm(hrm), _total_used(0) {
5995     assert(_hrm->num_free_regions() == 0, "pre-condition");
5996     if (!free_list_only) {
5997       assert(_old_set->is_empty(), "pre-condition");
5998     }
5999   }
6000 
6001   bool doHeapRegion(HeapRegion* r) {
6002     if (r->is_empty()) {
6003       // Add free regions to the free list
6004       r->set_free();
6005       r->set_allocation_context(AllocationContext::system());
6006       _hrm->insert_into_free_list(r);
6007     } else if (!_free_list_only) {
6008       assert(!r->is_young(), "we should not come across young regions");
6009 
6010       if (r->is_humongous()) {
6011         // We ignore humongous regions. We left the humongous set unchanged.
6012       } else {
6013         // Objects that were compacted would have ended up on regions
6014         // that were previously old or free.  Archive regions (which are
6015         // old) will not have been touched.
6016         assert(r->is_free() || r->is_old(), "invariant");
6017         // We now consider them old, so register as such. Leave
6018         // archive regions set that way, however, while still adding
6019         // them to the old set.
6020         if (!r->is_archive()) {
6021           r->set_old();
6022         }
6023         _old_set->add(r);
6024       }
6025       _total_used += r->used();
6026     }
6027 
6028     return false;
6029   }
6030 
6031   size_t total_used() {
6032     return _total_used;
6033   }
6034 };
6035 
6036 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6037   assert_at_safepoint(true /* should_be_vm_thread */);
6038 
6039   if (!free_list_only) {
6040     _young_list->empty_list();
6041   }
6042 
6043   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6044   heap_region_iterate(&cl);
6045 
6046   if (!free_list_only) {
6047     set_used(cl.total_used());
6048     if (_archive_allocator != NULL) {
6049       _archive_allocator->clear_used();
6050     }
6051   }
6052   assert(used_unlocked() == recalculate_used(),
6053          "inconsistent used_unlocked(), "
6054          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6055          used_unlocked(), recalculate_used());
6056 }
6057 
6058 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6059   _refine_cte_cl->set_concurrent(concurrent);
6060 }
6061 
6062 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6063   HeapRegion* hr = heap_region_containing(p);
6064   return hr->is_in(p);
6065 }
6066 
6067 // Methods for the mutator alloc region
6068 
6069 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6070                                                       bool force) {
6071   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6072   assert(!force || g1_policy()->can_expand_young_list(),
6073          "if force is true we should be able to expand the young list");
6074   bool young_list_full = g1_policy()->is_young_list_full();
6075   if (force || !young_list_full) {
6076     HeapRegion* new_alloc_region = new_region(word_size,
6077                                               false /* is_old */,
6078                                               false /* do_expand */);
6079     if (new_alloc_region != NULL) {
6080       set_region_short_lived_locked(new_alloc_region);
6081       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6082       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6083       return new_alloc_region;
6084     }
6085   }
6086   return NULL;
6087 }
6088 
6089 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6090                                                   size_t allocated_bytes) {
6091   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6092   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6093 
6094   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6095   increase_used(allocated_bytes);
6096   _hr_printer.retire(alloc_region);
6097   // We update the eden sizes here, when the region is retired,
6098   // instead of when it's allocated, since this is the point that its
6099   // used space has been recored in _summary_bytes_used.
6100   g1mm()->update_eden_size();
6101 }
6102 
6103 // Methods for the GC alloc regions
6104 
6105 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6106                                                  uint count,
6107                                                  InCSetState dest) {
6108   assert(FreeList_lock->owned_by_self(), "pre-condition");
6109 
6110   if (count < g1_policy()->max_regions(dest)) {
6111     const bool is_survivor = (dest.is_young());
6112     HeapRegion* new_alloc_region = new_region(word_size,
6113                                               !is_survivor,
6114                                               true /* do_expand */);
6115     if (new_alloc_region != NULL) {
6116       // We really only need to do this for old regions given that we
6117       // should never scan survivors. But it doesn't hurt to do it
6118       // for survivors too.
6119       new_alloc_region->record_timestamp();
6120       if (is_survivor) {
6121         new_alloc_region->set_survivor();
6122         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6123         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6124       } else {
6125         new_alloc_region->set_old();
6126         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6127         check_bitmaps("Old Region Allocation", new_alloc_region);
6128       }
6129       bool during_im = collector_state()->during_initial_mark_pause();
6130       new_alloc_region->note_start_of_copying(during_im);
6131       return new_alloc_region;
6132     }
6133   }
6134   return NULL;
6135 }
6136 
6137 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6138                                              size_t allocated_bytes,
6139                                              InCSetState dest) {
6140   bool during_im = collector_state()->during_initial_mark_pause();
6141   alloc_region->note_end_of_copying(during_im);
6142   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6143   if (dest.is_young()) {
6144     young_list()->add_survivor_region(alloc_region);
6145   } else {
6146     _old_set.add(alloc_region);
6147   }
6148   _hr_printer.retire(alloc_region);
6149 }
6150 
6151 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6152   bool expanded = false;
6153   uint index = _hrm.find_highest_free(&expanded);
6154 
6155   if (index != G1_NO_HRM_INDEX) {
6156     if (expanded) {
6157       ergo_verbose1(ErgoHeapSizing,
6158                     "attempt heap expansion",
6159                     ergo_format_reason("requested address range outside heap bounds")
6160                     ergo_format_byte("region size"),
6161                     HeapRegion::GrainWords * HeapWordSize);
6162     }
6163     _hrm.allocate_free_regions_starting_at(index, 1);
6164     return region_at(index);
6165   }
6166   return NULL;
6167 }
6168 
6169 // Heap region set verification
6170 
6171 class VerifyRegionListsClosure : public HeapRegionClosure {
6172 private:
6173   HeapRegionSet*   _old_set;
6174   HeapRegionSet*   _humongous_set;
6175   HeapRegionManager*   _hrm;
6176 
6177 public:
6178   HeapRegionSetCount _old_count;
6179   HeapRegionSetCount _humongous_count;
6180   HeapRegionSetCount _free_count;
6181 
6182   VerifyRegionListsClosure(HeapRegionSet* old_set,
6183                            HeapRegionSet* humongous_set,
6184                            HeapRegionManager* hrm) :
6185     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6186     _old_count(), _humongous_count(), _free_count(){ }
6187 
6188   bool doHeapRegion(HeapRegion* hr) {
6189     if (hr->is_young()) {
6190       // TODO
6191     } else if (hr->is_humongous()) {
6192       assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6193       _humongous_count.increment(1u, hr->capacity());
6194     } else if (hr->is_empty()) {
6195       assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6196       _free_count.increment(1u, hr->capacity());
6197     } else if (hr->is_old()) {
6198       assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6199       _old_count.increment(1u, hr->capacity());
6200     } else {
6201       // There are no other valid region types. Check for one invalid
6202       // one we can identify: pinned without old or humongous set.
6203       assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6204       ShouldNotReachHere();
6205     }
6206     return false;
6207   }
6208 
6209   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6210     guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6211     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6212               old_set->total_capacity_bytes(), _old_count.capacity());
6213 
6214     guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6215     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6216               humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6217 
6218     guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length());
6219     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6220               free_list->total_capacity_bytes(), _free_count.capacity());
6221   }
6222 };
6223 
6224 void G1CollectedHeap::verify_region_sets() {
6225   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6226 
6227   // First, check the explicit lists.
6228   _hrm.verify();
6229   {
6230     // Given that a concurrent operation might be adding regions to
6231     // the secondary free list we have to take the lock before
6232     // verifying it.
6233     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6234     _secondary_free_list.verify_list();
6235   }
6236 
6237   // If a concurrent region freeing operation is in progress it will
6238   // be difficult to correctly attributed any free regions we come
6239   // across to the correct free list given that they might belong to
6240   // one of several (free_list, secondary_free_list, any local lists,
6241   // etc.). So, if that's the case we will skip the rest of the
6242   // verification operation. Alternatively, waiting for the concurrent
6243   // operation to complete will have a non-trivial effect on the GC's
6244   // operation (no concurrent operation will last longer than the
6245   // interval between two calls to verification) and it might hide
6246   // any issues that we would like to catch during testing.
6247   if (free_regions_coming()) {
6248     return;
6249   }
6250 
6251   // Make sure we append the secondary_free_list on the free_list so
6252   // that all free regions we will come across can be safely
6253   // attributed to the free_list.
6254   append_secondary_free_list_if_not_empty_with_lock();
6255 
6256   // Finally, make sure that the region accounting in the lists is
6257   // consistent with what we see in the heap.
6258 
6259   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6260   heap_region_iterate(&cl);
6261   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6262 }
6263 
6264 // Optimized nmethod scanning
6265 
6266 class RegisterNMethodOopClosure: public OopClosure {
6267   G1CollectedHeap* _g1h;
6268   nmethod* _nm;
6269 
6270   template <class T> void do_oop_work(T* p) {
6271     T heap_oop = oopDesc::load_heap_oop(p);
6272     if (!oopDesc::is_null(heap_oop)) {
6273       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6274       HeapRegion* hr = _g1h->heap_region_containing(obj);
6275       assert(!hr->is_continues_humongous(),
6276              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6277              " starting at " HR_FORMAT,
6278              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6279 
6280       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6281       hr->add_strong_code_root_locked(_nm);
6282     }
6283   }
6284 
6285 public:
6286   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6287     _g1h(g1h), _nm(nm) {}
6288 
6289   void do_oop(oop* p)       { do_oop_work(p); }
6290   void do_oop(narrowOop* p) { do_oop_work(p); }
6291 };
6292 
6293 class UnregisterNMethodOopClosure: public OopClosure {
6294   G1CollectedHeap* _g1h;
6295   nmethod* _nm;
6296 
6297   template <class T> void do_oop_work(T* p) {
6298     T heap_oop = oopDesc::load_heap_oop(p);
6299     if (!oopDesc::is_null(heap_oop)) {
6300       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6301       HeapRegion* hr = _g1h->heap_region_containing(obj);
6302       assert(!hr->is_continues_humongous(),
6303              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6304              " starting at " HR_FORMAT,
6305              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6306 
6307       hr->remove_strong_code_root(_nm);
6308     }
6309   }
6310 
6311 public:
6312   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6313     _g1h(g1h), _nm(nm) {}
6314 
6315   void do_oop(oop* p)       { do_oop_work(p); }
6316   void do_oop(narrowOop* p) { do_oop_work(p); }
6317 };
6318 
6319 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6320   CollectedHeap::register_nmethod(nm);
6321 
6322   guarantee(nm != NULL, "sanity");
6323   RegisterNMethodOopClosure reg_cl(this, nm);
6324   nm->oops_do(&reg_cl);
6325 }
6326 
6327 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6328   CollectedHeap::unregister_nmethod(nm);
6329 
6330   guarantee(nm != NULL, "sanity");
6331   UnregisterNMethodOopClosure reg_cl(this, nm);
6332   nm->oops_do(&reg_cl, true);
6333 }
6334 
6335 void G1CollectedHeap::purge_code_root_memory() {
6336   double purge_start = os::elapsedTime();
6337   G1CodeRootSet::purge();
6338   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6339   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6340 }
6341 
6342 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6343   G1CollectedHeap* _g1h;
6344 
6345 public:
6346   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6347     _g1h(g1h) {}
6348 
6349   void do_code_blob(CodeBlob* cb) {
6350     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6351     if (nm == NULL) {
6352       return;
6353     }
6354 
6355     if (ScavengeRootsInCode) {
6356       _g1h->register_nmethod(nm);
6357     }
6358   }
6359 };
6360 
6361 void G1CollectedHeap::rebuild_strong_code_roots() {
6362   RebuildStrongCodeRootClosure blob_cl(this);
6363   CodeCache::blobs_do(&blob_cl);
6364 }