rev 13232 : imported patch parallel-fullgc-stefanj
rev 13237 : imported patch 8183226-periodic-rem-set-summary-accesses-uninitialized-stuff
rev 13238 : imported patch 8183226-eridk-sjohanss-review
rev 13239 : imported patch 8183128-cleanup-refinecardtableentryclosure

   1 /*
   2  * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/bufferingOopClosure.hpp"
  32 #include "gc/g1/concurrentG1Refine.hpp"
  33 #include "gc/g1/concurrentG1RefineThread.hpp"
  34 #include "gc/g1/concurrentMarkThread.inline.hpp"
  35 #include "gc/g1/g1Allocator.inline.hpp"
  36 #include "gc/g1/g1CollectedHeap.inline.hpp"
  37 #include "gc/g1/g1CollectionSet.hpp"
  38 #include "gc/g1/g1CollectorPolicy.hpp"
  39 #include "gc/g1/g1CollectorState.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1FullCollector.hpp"
  42 #include "gc/g1/g1FullGCScope.hpp"
  43 #include "gc/g1/g1GCPhaseTimes.hpp"
  44 #include "gc/g1/g1HeapSizingPolicy.hpp"
  45 #include "gc/g1/g1HeapTransition.hpp"
  46 #include "gc/g1/g1HeapVerifier.hpp"
  47 #include "gc/g1/g1HotCardCache.hpp"
  48 #include "gc/g1/g1OopClosures.inline.hpp"
  49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  50 #include "gc/g1/g1Policy.hpp"
  51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  52 #include "gc/g1/g1RemSet.inline.hpp"
  53 #include "gc/g1/g1RootClosures.hpp"
  54 #include "gc/g1/g1RootProcessor.hpp"
  55 #include "gc/g1/g1StringDedup.hpp"
  56 #include "gc/g1/g1YCTypes.hpp"
  57 #include "gc/g1/heapRegion.inline.hpp"
  58 #include "gc/g1/heapRegionRemSet.hpp"
  59 #include "gc/g1/heapRegionSet.inline.hpp"
  60 #include "gc/g1/suspendibleThreadSet.hpp"
  61 #include "gc/g1/vm_operations_g1.hpp"
  62 #include "gc/shared/gcHeapSummary.hpp"
  63 #include "gc/shared/gcId.hpp"
  64 #include "gc/shared/gcLocker.inline.hpp"
  65 #include "gc/shared/gcTimer.hpp"
  66 #include "gc/shared/gcTrace.hpp"
  67 #include "gc/shared/gcTraceTime.inline.hpp"
  68 #include "gc/shared/generationSpec.hpp"
  69 #include "gc/shared/isGCActiveMark.hpp"
  70 #include "gc/shared/preservedMarks.inline.hpp"
  71 #include "gc/shared/referenceProcessor.inline.hpp"
  72 #include "gc/shared/taskqueue.inline.hpp"
  73 #include "logging/log.hpp"
  74 #include "memory/allocation.hpp"
  75 #include "memory/iterator.hpp"
  76 #include "memory/resourceArea.hpp"
  77 #include "oops/oop.inline.hpp"
  78 #include "prims/resolvedMethodTable.hpp"
  79 #include "runtime/atomic.hpp"
  80 #include "runtime/init.hpp"
  81 #include "runtime/orderAccess.inline.hpp"
  82 #include "runtime/vmThread.hpp"
  83 #include "utilities/align.hpp"
  84 #include "utilities/globalDefinitions.hpp"
  85 #include "utilities/stack.inline.hpp"
  86 
  87 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  88 
  89 // INVARIANTS/NOTES
  90 //
  91 // All allocation activity covered by the G1CollectedHeap interface is
  92 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  93 // and allocate_new_tlab, which are the "entry" points to the
  94 // allocation code from the rest of the JVM.  (Note that this does not
  95 // apply to TLAB allocation, which is not part of this interface: it
  96 // is done by clients of this interface.)
  97 
  98 // Local to this file.
  99 
 100 class RefineCardTableEntryClosure: public CardTableEntryClosure {
 101   bool _concurrent;
 102 public:
 103   RefineCardTableEntryClosure() : _concurrent(true) { }
 104 
 105   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 106     G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
 107 
 108     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 109       // Caller will actually yield.
 110       return false;
 111     }
 112     // Otherwise, we finished successfully; return true.
 113     return true;
 114   }
 115 
 116   void set_concurrent(bool b) { _concurrent = b; }
 117 };
 118 
 119 
 120 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 121  private:
 122   size_t _num_dirtied;
 123   G1CollectedHeap* _g1h;
 124   G1SATBCardTableLoggingModRefBS* _g1_bs;
 125 
 126   HeapRegion* region_for_card(jbyte* card_ptr) const {
 127     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 128   }
 129 
 130   bool will_become_free(HeapRegion* hr) const {
 131     // A region will be freed by free_collection_set if the region is in the
 132     // collection set and has not had an evacuation failure.
 133     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 134   }
 135 
 136  public:
 137   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 138     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 139 
 140   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 141     HeapRegion* hr = region_for_card(card_ptr);
 142 
 143     // Should only dirty cards in regions that won't be freed.
 144     if (!will_become_free(hr)) {
 145       *card_ptr = CardTableModRefBS::dirty_card_val();
 146       _num_dirtied++;
 147     }
 148 
 149     return true;
 150   }
 151 
 152   size_t num_dirtied()   const { return _num_dirtied; }
 153 };
 154 
 155 
 156 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 157   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 158 }
 159 
 160 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 161   // The from card cache is not the memory that is actually committed. So we cannot
 162   // take advantage of the zero_filled parameter.
 163   reset_from_card_cache(start_idx, num_regions);
 164 }
 165 
 166 // Returns true if the reference points to an object that
 167 // can move in an incremental collection.
 168 bool G1CollectedHeap::is_scavengable(const void* p) {
 169   HeapRegion* hr = heap_region_containing(p);
 170   return !hr->is_pinned();
 171 }
 172 
 173 
 174 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 175                                              MemRegion mr) {
 176   return new HeapRegion(hrs_index, bot(), mr);
 177 }
 178 
 179 // Private methods.
 180 
 181 HeapRegion*
 182 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 183   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 184   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 185     if (!_secondary_free_list.is_empty()) {
 186       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 187                                       "secondary_free_list has %u entries",
 188                                       _secondary_free_list.length());
 189       // It looks as if there are free regions available on the
 190       // secondary_free_list. Let's move them to the free_list and try
 191       // again to allocate from it.
 192       append_secondary_free_list();
 193 
 194       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 195              "empty we should have moved at least one entry to the free_list");
 196       HeapRegion* res = _hrm.allocate_free_region(is_old);
 197       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 198                                       "allocated " HR_FORMAT " from secondary_free_list",
 199                                       HR_FORMAT_PARAMS(res));
 200       return res;
 201     }
 202 
 203     // Wait here until we get notified either when (a) there are no
 204     // more free regions coming or (b) some regions have been moved on
 205     // the secondary_free_list.
 206     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 207   }
 208 
 209   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 210                                   "could not allocate from secondary_free_list");
 211   return NULL;
 212 }
 213 
 214 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 215   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 216          "the only time we use this to allocate a humongous region is "
 217          "when we are allocating a single humongous region");
 218 
 219   HeapRegion* res;
 220   if (G1StressConcRegionFreeing) {
 221     if (!_secondary_free_list.is_empty()) {
 222       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 223                                       "forced to look at the secondary_free_list");
 224       res = new_region_try_secondary_free_list(is_old);
 225       if (res != NULL) {
 226         return res;
 227       }
 228     }
 229   }
 230 
 231   res = _hrm.allocate_free_region(is_old);
 232 
 233   if (res == NULL) {
 234     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 235                                     "res == NULL, trying the secondary_free_list");
 236     res = new_region_try_secondary_free_list(is_old);
 237   }
 238   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 239     // Currently, only attempts to allocate GC alloc regions set
 240     // do_expand to true. So, we should only reach here during a
 241     // safepoint. If this assumption changes we might have to
 242     // reconsider the use of _expand_heap_after_alloc_failure.
 243     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 244 
 245     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 246                               word_size * HeapWordSize);
 247 
 248     if (expand(word_size * HeapWordSize)) {
 249       // Given that expand() succeeded in expanding the heap, and we
 250       // always expand the heap by an amount aligned to the heap
 251       // region size, the free list should in theory not be empty.
 252       // In either case allocate_free_region() will check for NULL.
 253       res = _hrm.allocate_free_region(is_old);
 254     } else {
 255       _expand_heap_after_alloc_failure = false;
 256     }
 257   }
 258   return res;
 259 }
 260 
 261 HeapWord*
 262 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 263                                                            uint num_regions,
 264                                                            size_t word_size,
 265                                                            AllocationContext_t context) {
 266   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 267   assert(is_humongous(word_size), "word_size should be humongous");
 268   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 269 
 270   // Index of last region in the series.
 271   uint last = first + num_regions - 1;
 272 
 273   // We need to initialize the region(s) we just discovered. This is
 274   // a bit tricky given that it can happen concurrently with
 275   // refinement threads refining cards on these regions and
 276   // potentially wanting to refine the BOT as they are scanning
 277   // those cards (this can happen shortly after a cleanup; see CR
 278   // 6991377). So we have to set up the region(s) carefully and in
 279   // a specific order.
 280 
 281   // The word size sum of all the regions we will allocate.
 282   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 283   assert(word_size <= word_size_sum, "sanity");
 284 
 285   // This will be the "starts humongous" region.
 286   HeapRegion* first_hr = region_at(first);
 287   // The header of the new object will be placed at the bottom of
 288   // the first region.
 289   HeapWord* new_obj = first_hr->bottom();
 290   // This will be the new top of the new object.
 291   HeapWord* obj_top = new_obj + word_size;
 292 
 293   // First, we need to zero the header of the space that we will be
 294   // allocating. When we update top further down, some refinement
 295   // threads might try to scan the region. By zeroing the header we
 296   // ensure that any thread that will try to scan the region will
 297   // come across the zero klass word and bail out.
 298   //
 299   // NOTE: It would not have been correct to have used
 300   // CollectedHeap::fill_with_object() and make the space look like
 301   // an int array. The thread that is doing the allocation will
 302   // later update the object header to a potentially different array
 303   // type and, for a very short period of time, the klass and length
 304   // fields will be inconsistent. This could cause a refinement
 305   // thread to calculate the object size incorrectly.
 306   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 307 
 308   // Next, pad out the unused tail of the last region with filler
 309   // objects, for improved usage accounting.
 310   // How many words we use for filler objects.
 311   size_t word_fill_size = word_size_sum - word_size;
 312 
 313   // How many words memory we "waste" which cannot hold a filler object.
 314   size_t words_not_fillable = 0;
 315 
 316   if (word_fill_size >= min_fill_size()) {
 317     fill_with_objects(obj_top, word_fill_size);
 318   } else if (word_fill_size > 0) {
 319     // We have space to fill, but we cannot fit an object there.
 320     words_not_fillable = word_fill_size;
 321     word_fill_size = 0;
 322   }
 323 
 324   // We will set up the first region as "starts humongous". This
 325   // will also update the BOT covering all the regions to reflect
 326   // that there is a single object that starts at the bottom of the
 327   // first region.
 328   first_hr->set_starts_humongous(obj_top, word_fill_size);
 329   first_hr->set_allocation_context(context);
 330   // Then, if there are any, we will set up the "continues
 331   // humongous" regions.
 332   HeapRegion* hr = NULL;
 333   for (uint i = first + 1; i <= last; ++i) {
 334     hr = region_at(i);
 335     hr->set_continues_humongous(first_hr);
 336     hr->set_allocation_context(context);
 337   }
 338 
 339   // Up to this point no concurrent thread would have been able to
 340   // do any scanning on any region in this series. All the top
 341   // fields still point to bottom, so the intersection between
 342   // [bottom,top] and [card_start,card_end] will be empty. Before we
 343   // update the top fields, we'll do a storestore to make sure that
 344   // no thread sees the update to top before the zeroing of the
 345   // object header and the BOT initialization.
 346   OrderAccess::storestore();
 347 
 348   // Now, we will update the top fields of the "continues humongous"
 349   // regions except the last one.
 350   for (uint i = first; i < last; ++i) {
 351     hr = region_at(i);
 352     hr->set_top(hr->end());
 353   }
 354 
 355   hr = region_at(last);
 356   // If we cannot fit a filler object, we must set top to the end
 357   // of the humongous object, otherwise we cannot iterate the heap
 358   // and the BOT will not be complete.
 359   hr->set_top(hr->end() - words_not_fillable);
 360 
 361   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 362          "obj_top should be in last region");
 363 
 364   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 365 
 366   assert(words_not_fillable == 0 ||
 367          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 368          "Miscalculation in humongous allocation");
 369 
 370   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 371 
 372   for (uint i = first; i <= last; ++i) {
 373     hr = region_at(i);
 374     _humongous_set.add(hr);
 375     _hr_printer.alloc(hr);
 376   }
 377 
 378   return new_obj;
 379 }
 380 
 381 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 382   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 383   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 384 }
 385 
 386 // If could fit into free regions w/o expansion, try.
 387 // Otherwise, if can expand, do so.
 388 // Otherwise, if using ex regions might help, try with ex given back.
 389 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 390   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 391 
 392   _verifier->verify_region_sets_optional();
 393 
 394   uint first = G1_NO_HRM_INDEX;
 395   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 396 
 397   if (obj_regions == 1) {
 398     // Only one region to allocate, try to use a fast path by directly allocating
 399     // from the free lists. Do not try to expand here, we will potentially do that
 400     // later.
 401     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 402     if (hr != NULL) {
 403       first = hr->hrm_index();
 404     }
 405   } else {
 406     // We can't allocate humongous regions spanning more than one region while
 407     // cleanupComplete() is running, since some of the regions we find to be
 408     // empty might not yet be added to the free list. It is not straightforward
 409     // to know in which list they are on so that we can remove them. We only
 410     // need to do this if we need to allocate more than one region to satisfy the
 411     // current humongous allocation request. If we are only allocating one region
 412     // we use the one-region region allocation code (see above), that already
 413     // potentially waits for regions from the secondary free list.
 414     wait_while_free_regions_coming();
 415     append_secondary_free_list_if_not_empty_with_lock();
 416 
 417     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 418     // are lucky enough to find some.
 419     first = _hrm.find_contiguous_only_empty(obj_regions);
 420     if (first != G1_NO_HRM_INDEX) {
 421       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 422     }
 423   }
 424 
 425   if (first == G1_NO_HRM_INDEX) {
 426     // Policy: We could not find enough regions for the humongous object in the
 427     // free list. Look through the heap to find a mix of free and uncommitted regions.
 428     // If so, try expansion.
 429     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 430     if (first != G1_NO_HRM_INDEX) {
 431       // We found something. Make sure these regions are committed, i.e. expand
 432       // the heap. Alternatively we could do a defragmentation GC.
 433       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 434                                     word_size * HeapWordSize);
 435 
 436       _hrm.expand_at(first, obj_regions, workers());
 437       g1_policy()->record_new_heap_size(num_regions());
 438 
 439 #ifdef ASSERT
 440       for (uint i = first; i < first + obj_regions; ++i) {
 441         HeapRegion* hr = region_at(i);
 442         assert(hr->is_free(), "sanity");
 443         assert(hr->is_empty(), "sanity");
 444         assert(is_on_master_free_list(hr), "sanity");
 445       }
 446 #endif
 447       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 448     } else {
 449       // Policy: Potentially trigger a defragmentation GC.
 450     }
 451   }
 452 
 453   HeapWord* result = NULL;
 454   if (first != G1_NO_HRM_INDEX) {
 455     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 456                                                        word_size, context);
 457     assert(result != NULL, "it should always return a valid result");
 458 
 459     // A successful humongous object allocation changes the used space
 460     // information of the old generation so we need to recalculate the
 461     // sizes and update the jstat counters here.
 462     g1mm()->update_sizes();
 463   }
 464 
 465   _verifier->verify_region_sets_optional();
 466 
 467   return result;
 468 }
 469 
 470 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 471   assert_heap_not_locked_and_not_at_safepoint();
 472   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 473 
 474   uint dummy_gc_count_before;
 475   uint dummy_gclocker_retry_count = 0;
 476   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 477 }
 478 
 479 HeapWord*
 480 G1CollectedHeap::mem_allocate(size_t word_size,
 481                               bool*  gc_overhead_limit_was_exceeded) {
 482   assert_heap_not_locked_and_not_at_safepoint();
 483 
 484   // Loop until the allocation is satisfied, or unsatisfied after GC.
 485   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 486     uint gc_count_before;
 487 
 488     HeapWord* result = NULL;
 489     if (!is_humongous(word_size)) {
 490       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 491     } else {
 492       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 493     }
 494     if (result != NULL) {
 495       return result;
 496     }
 497 
 498     // Create the garbage collection operation...
 499     VM_G1CollectForAllocation op(gc_count_before, word_size);
 500     op.set_allocation_context(AllocationContext::current());
 501 
 502     // ...and get the VM thread to execute it.
 503     VMThread::execute(&op);
 504 
 505     if (op.prologue_succeeded() && op.pause_succeeded()) {
 506       // If the operation was successful we'll return the result even
 507       // if it is NULL. If the allocation attempt failed immediately
 508       // after a Full GC, it's unlikely we'll be able to allocate now.
 509       HeapWord* result = op.result();
 510       if (result != NULL && !is_humongous(word_size)) {
 511         // Allocations that take place on VM operations do not do any
 512         // card dirtying and we have to do it here. We only have to do
 513         // this for non-humongous allocations, though.
 514         dirty_young_block(result, word_size);
 515       }
 516       return result;
 517     } else {
 518       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 519         return NULL;
 520       }
 521       assert(op.result() == NULL,
 522              "the result should be NULL if the VM op did not succeed");
 523     }
 524 
 525     // Give a warning if we seem to be looping forever.
 526     if ((QueuedAllocationWarningCount > 0) &&
 527         (try_count % QueuedAllocationWarningCount == 0)) {
 528       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 529     }
 530   }
 531 
 532   ShouldNotReachHere();
 533   return NULL;
 534 }
 535 
 536 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 537                                                    AllocationContext_t context,
 538                                                    uint* gc_count_before_ret,
 539                                                    uint* gclocker_retry_count_ret) {
 540   // Make sure you read the note in attempt_allocation_humongous().
 541 
 542   assert_heap_not_locked_and_not_at_safepoint();
 543   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 544          "be called for humongous allocation requests");
 545 
 546   // We should only get here after the first-level allocation attempt
 547   // (attempt_allocation()) failed to allocate.
 548 
 549   // We will loop until a) we manage to successfully perform the
 550   // allocation or b) we successfully schedule a collection which
 551   // fails to perform the allocation. b) is the only case when we'll
 552   // return NULL.
 553   HeapWord* result = NULL;
 554   for (int try_count = 1; /* we'll return */; try_count += 1) {
 555     bool should_try_gc;
 556     uint gc_count_before;
 557 
 558     {
 559       MutexLockerEx x(Heap_lock);
 560       result = _allocator->attempt_allocation_locked(word_size, context);
 561       if (result != NULL) {
 562         return result;
 563       }
 564 
 565       if (GCLocker::is_active_and_needs_gc()) {
 566         if (g1_policy()->can_expand_young_list()) {
 567           // No need for an ergo verbose message here,
 568           // can_expand_young_list() does this when it returns true.
 569           result = _allocator->attempt_allocation_force(word_size, context);
 570           if (result != NULL) {
 571             return result;
 572           }
 573         }
 574         should_try_gc = false;
 575       } else {
 576         // The GCLocker may not be active but the GCLocker initiated
 577         // GC may not yet have been performed (GCLocker::needs_gc()
 578         // returns true). In this case we do not try this GC and
 579         // wait until the GCLocker initiated GC is performed, and
 580         // then retry the allocation.
 581         if (GCLocker::needs_gc()) {
 582           should_try_gc = false;
 583         } else {
 584           // Read the GC count while still holding the Heap_lock.
 585           gc_count_before = total_collections();
 586           should_try_gc = true;
 587         }
 588       }
 589     }
 590 
 591     if (should_try_gc) {
 592       bool succeeded;
 593       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 594                                    GCCause::_g1_inc_collection_pause);
 595       if (result != NULL) {
 596         assert(succeeded, "only way to get back a non-NULL result");
 597         return result;
 598       }
 599 
 600       if (succeeded) {
 601         // If we get here we successfully scheduled a collection which
 602         // failed to allocate. No point in trying to allocate
 603         // further. We'll just return NULL.
 604         MutexLockerEx x(Heap_lock);
 605         *gc_count_before_ret = total_collections();
 606         return NULL;
 607       }
 608     } else {
 609       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 610         MutexLockerEx x(Heap_lock);
 611         *gc_count_before_ret = total_collections();
 612         return NULL;
 613       }
 614       // The GCLocker is either active or the GCLocker initiated
 615       // GC has not yet been performed. Stall until it is and
 616       // then retry the allocation.
 617       GCLocker::stall_until_clear();
 618       (*gclocker_retry_count_ret) += 1;
 619     }
 620 
 621     // We can reach here if we were unsuccessful in scheduling a
 622     // collection (because another thread beat us to it) or if we were
 623     // stalled due to the GC locker. In either can we should retry the
 624     // allocation attempt in case another thread successfully
 625     // performed a collection and reclaimed enough space. We do the
 626     // first attempt (without holding the Heap_lock) here and the
 627     // follow-on attempt will be at the start of the next loop
 628     // iteration (after taking the Heap_lock).
 629     result = _allocator->attempt_allocation(word_size, context);
 630     if (result != NULL) {
 631       return result;
 632     }
 633 
 634     // Give a warning if we seem to be looping forever.
 635     if ((QueuedAllocationWarningCount > 0) &&
 636         (try_count % QueuedAllocationWarningCount == 0)) {
 637       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 638                       "retries %d times", try_count);
 639     }
 640   }
 641 
 642   ShouldNotReachHere();
 643   return NULL;
 644 }
 645 
 646 void G1CollectedHeap::begin_archive_alloc_range() {
 647   assert_at_safepoint(true /* should_be_vm_thread */);
 648   if (_archive_allocator == NULL) {
 649     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 650   }
 651 }
 652 
 653 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 654   // Allocations in archive regions cannot be of a size that would be considered
 655   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 656   // may be different at archive-restore time.
 657   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 658 }
 659 
 660 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 661   assert_at_safepoint(true /* should_be_vm_thread */);
 662   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 663   if (is_archive_alloc_too_large(word_size)) {
 664     return NULL;
 665   }
 666   return _archive_allocator->archive_mem_allocate(word_size);
 667 }
 668 
 669 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 670                                               size_t end_alignment_in_bytes) {
 671   assert_at_safepoint(true /* should_be_vm_thread */);
 672   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 673 
 674   // Call complete_archive to do the real work, filling in the MemRegion
 675   // array with the archive regions.
 676   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 677   delete _archive_allocator;
 678   _archive_allocator = NULL;
 679 }
 680 
 681 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 682   assert(ranges != NULL, "MemRegion array NULL");
 683   assert(count != 0, "No MemRegions provided");
 684   MemRegion reserved = _hrm.reserved();
 685   for (size_t i = 0; i < count; i++) {
 686     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 687       return false;
 688     }
 689   }
 690   return true;
 691 }
 692 
 693 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 694   assert(!is_init_completed(), "Expect to be called at JVM init time");
 695   assert(ranges != NULL, "MemRegion array NULL");
 696   assert(count != 0, "No MemRegions provided");
 697   MutexLockerEx x(Heap_lock);
 698 
 699   MemRegion reserved = _hrm.reserved();
 700   HeapWord* prev_last_addr = NULL;
 701   HeapRegion* prev_last_region = NULL;
 702 
 703   // Temporarily disable pretouching of heap pages. This interface is used
 704   // when mmap'ing archived heap data in, so pre-touching is wasted.
 705   FlagSetting fs(AlwaysPreTouch, false);
 706 
 707   // Enable archive object checking used by G1MarkSweep. We have to let it know
 708   // about each archive range, so that objects in those ranges aren't marked.
 709   G1ArchiveAllocator::enable_archive_object_check();
 710 
 711   // For each specified MemRegion range, allocate the corresponding G1
 712   // regions and mark them as archive regions. We expect the ranges in
 713   // ascending starting address order, without overlap.
 714   for (size_t i = 0; i < count; i++) {
 715     MemRegion curr_range = ranges[i];
 716     HeapWord* start_address = curr_range.start();
 717     size_t word_size = curr_range.word_size();
 718     HeapWord* last_address = curr_range.last();
 719     size_t commits = 0;
 720 
 721     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 722               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 723               p2i(start_address), p2i(last_address));
 724     guarantee(start_address > prev_last_addr,
 725               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 726               p2i(start_address), p2i(prev_last_addr));
 727     prev_last_addr = last_address;
 728 
 729     // Check for ranges that start in the same G1 region in which the previous
 730     // range ended, and adjust the start address so we don't try to allocate
 731     // the same region again. If the current range is entirely within that
 732     // region, skip it, just adjusting the recorded top.
 733     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 734     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 735       start_address = start_region->end();
 736       if (start_address > last_address) {
 737         increase_used(word_size * HeapWordSize);
 738         start_region->set_top(last_address + 1);
 739         continue;
 740       }
 741       start_region->set_top(start_address);
 742       curr_range = MemRegion(start_address, last_address + 1);
 743       start_region = _hrm.addr_to_region(start_address);
 744     }
 745 
 746     // Perform the actual region allocation, exiting if it fails.
 747     // Then note how much new space we have allocated.
 748     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 749       return false;
 750     }
 751     increase_used(word_size * HeapWordSize);
 752     if (commits != 0) {
 753       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 754                                 HeapRegion::GrainWords * HeapWordSize * commits);
 755 
 756     }
 757 
 758     // Mark each G1 region touched by the range as archive, add it to the old set,
 759     // and set the allocation context and top.
 760     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 761     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 762     prev_last_region = last_region;
 763 
 764     while (curr_region != NULL) {
 765       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 766              "Region already in use (index %u)", curr_region->hrm_index());
 767       curr_region->set_allocation_context(AllocationContext::system());
 768       curr_region->set_archive();
 769       _hr_printer.alloc(curr_region);
 770       _old_set.add(curr_region);
 771       if (curr_region != last_region) {
 772         curr_region->set_top(curr_region->end());
 773         curr_region = _hrm.next_region_in_heap(curr_region);
 774       } else {
 775         curr_region->set_top(last_address + 1);
 776         curr_region = NULL;
 777       }
 778     }
 779 
 780     // Notify mark-sweep of the archive range.
 781     G1ArchiveAllocator::set_range_archive(curr_range, true);
 782   }
 783   return true;
 784 }
 785 
 786 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 787   assert(!is_init_completed(), "Expect to be called at JVM init time");
 788   assert(ranges != NULL, "MemRegion array NULL");
 789   assert(count != 0, "No MemRegions provided");
 790   MemRegion reserved = _hrm.reserved();
 791   HeapWord *prev_last_addr = NULL;
 792   HeapRegion* prev_last_region = NULL;
 793 
 794   // For each MemRegion, create filler objects, if needed, in the G1 regions
 795   // that contain the address range. The address range actually within the
 796   // MemRegion will not be modified. That is assumed to have been initialized
 797   // elsewhere, probably via an mmap of archived heap data.
 798   MutexLockerEx x(Heap_lock);
 799   for (size_t i = 0; i < count; i++) {
 800     HeapWord* start_address = ranges[i].start();
 801     HeapWord* last_address = ranges[i].last();
 802 
 803     assert(reserved.contains(start_address) && reserved.contains(last_address),
 804            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 805            p2i(start_address), p2i(last_address));
 806     assert(start_address > prev_last_addr,
 807            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 808            p2i(start_address), p2i(prev_last_addr));
 809 
 810     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 811     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 812     HeapWord* bottom_address = start_region->bottom();
 813 
 814     // Check for a range beginning in the same region in which the
 815     // previous one ended.
 816     if (start_region == prev_last_region) {
 817       bottom_address = prev_last_addr + 1;
 818     }
 819 
 820     // Verify that the regions were all marked as archive regions by
 821     // alloc_archive_regions.
 822     HeapRegion* curr_region = start_region;
 823     while (curr_region != NULL) {
 824       guarantee(curr_region->is_archive(),
 825                 "Expected archive region at index %u", curr_region->hrm_index());
 826       if (curr_region != last_region) {
 827         curr_region = _hrm.next_region_in_heap(curr_region);
 828       } else {
 829         curr_region = NULL;
 830       }
 831     }
 832 
 833     prev_last_addr = last_address;
 834     prev_last_region = last_region;
 835 
 836     // Fill the memory below the allocated range with dummy object(s),
 837     // if the region bottom does not match the range start, or if the previous
 838     // range ended within the same G1 region, and there is a gap.
 839     if (start_address != bottom_address) {
 840       size_t fill_size = pointer_delta(start_address, bottom_address);
 841       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 842       increase_used(fill_size * HeapWordSize);
 843     }
 844   }
 845 }
 846 
 847 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 848                                                      uint* gc_count_before_ret,
 849                                                      uint* gclocker_retry_count_ret) {
 850   assert_heap_not_locked_and_not_at_safepoint();
 851   assert(!is_humongous(word_size), "attempt_allocation() should not "
 852          "be called for humongous allocation requests");
 853 
 854   AllocationContext_t context = AllocationContext::current();
 855   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 856 
 857   if (result == NULL) {
 858     result = attempt_allocation_slow(word_size,
 859                                      context,
 860                                      gc_count_before_ret,
 861                                      gclocker_retry_count_ret);
 862   }
 863   assert_heap_not_locked();
 864   if (result != NULL) {
 865     dirty_young_block(result, word_size);
 866   }
 867   return result;
 868 }
 869 
 870 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 871   assert(!is_init_completed(), "Expect to be called at JVM init time");
 872   assert(ranges != NULL, "MemRegion array NULL");
 873   assert(count != 0, "No MemRegions provided");
 874   MemRegion reserved = _hrm.reserved();
 875   HeapWord* prev_last_addr = NULL;
 876   HeapRegion* prev_last_region = NULL;
 877   size_t size_used = 0;
 878   size_t uncommitted_regions = 0;
 879 
 880   // For each Memregion, free the G1 regions that constitute it, and
 881   // notify mark-sweep that the range is no longer to be considered 'archive.'
 882   MutexLockerEx x(Heap_lock);
 883   for (size_t i = 0; i < count; i++) {
 884     HeapWord* start_address = ranges[i].start();
 885     HeapWord* last_address = ranges[i].last();
 886 
 887     assert(reserved.contains(start_address) && reserved.contains(last_address),
 888            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 889            p2i(start_address), p2i(last_address));
 890     assert(start_address > prev_last_addr,
 891            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 892            p2i(start_address), p2i(prev_last_addr));
 893     size_used += ranges[i].byte_size();
 894     prev_last_addr = last_address;
 895 
 896     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 897     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 898 
 899     // Check for ranges that start in the same G1 region in which the previous
 900     // range ended, and adjust the start address so we don't try to free
 901     // the same region again. If the current range is entirely within that
 902     // region, skip it.
 903     if (start_region == prev_last_region) {
 904       start_address = start_region->end();
 905       if (start_address > last_address) {
 906         continue;
 907       }
 908       start_region = _hrm.addr_to_region(start_address);
 909     }
 910     prev_last_region = last_region;
 911 
 912     // After verifying that each region was marked as an archive region by
 913     // alloc_archive_regions, set it free and empty and uncommit it.
 914     HeapRegion* curr_region = start_region;
 915     while (curr_region != NULL) {
 916       guarantee(curr_region->is_archive(),
 917                 "Expected archive region at index %u", curr_region->hrm_index());
 918       uint curr_index = curr_region->hrm_index();
 919       _old_set.remove(curr_region);
 920       curr_region->set_free();
 921       curr_region->set_top(curr_region->bottom());
 922       if (curr_region != last_region) {
 923         curr_region = _hrm.next_region_in_heap(curr_region);
 924       } else {
 925         curr_region = NULL;
 926       }
 927       _hrm.shrink_at(curr_index, 1);
 928       uncommitted_regions++;
 929     }
 930 
 931     // Notify mark-sweep that this is no longer an archive range.
 932     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 933   }
 934 
 935   if (uncommitted_regions != 0) {
 936     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 937                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 938   }
 939   decrease_used(size_used);
 940 }
 941 
 942 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 943                                                         uint* gc_count_before_ret,
 944                                                         uint* gclocker_retry_count_ret) {
 945   // The structure of this method has a lot of similarities to
 946   // attempt_allocation_slow(). The reason these two were not merged
 947   // into a single one is that such a method would require several "if
 948   // allocation is not humongous do this, otherwise do that"
 949   // conditional paths which would obscure its flow. In fact, an early
 950   // version of this code did use a unified method which was harder to
 951   // follow and, as a result, it had subtle bugs that were hard to
 952   // track down. So keeping these two methods separate allows each to
 953   // be more readable. It will be good to keep these two in sync as
 954   // much as possible.
 955 
 956   assert_heap_not_locked_and_not_at_safepoint();
 957   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 958          "should only be called for humongous allocations");
 959 
 960   // Humongous objects can exhaust the heap quickly, so we should check if we
 961   // need to start a marking cycle at each humongous object allocation. We do
 962   // the check before we do the actual allocation. The reason for doing it
 963   // before the allocation is that we avoid having to keep track of the newly
 964   // allocated memory while we do a GC.
 965   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 966                                            word_size)) {
 967     collect(GCCause::_g1_humongous_allocation);
 968   }
 969 
 970   // We will loop until a) we manage to successfully perform the
 971   // allocation or b) we successfully schedule a collection which
 972   // fails to perform the allocation. b) is the only case when we'll
 973   // return NULL.
 974   HeapWord* result = NULL;
 975   for (int try_count = 1; /* we'll return */; try_count += 1) {
 976     bool should_try_gc;
 977     uint gc_count_before;
 978 
 979     {
 980       MutexLockerEx x(Heap_lock);
 981 
 982       // Given that humongous objects are not allocated in young
 983       // regions, we'll first try to do the allocation without doing a
 984       // collection hoping that there's enough space in the heap.
 985       result = humongous_obj_allocate(word_size, AllocationContext::current());
 986       if (result != NULL) {
 987         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 988         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 989         return result;
 990       }
 991 
 992       if (GCLocker::is_active_and_needs_gc()) {
 993         should_try_gc = false;
 994       } else {
 995          // The GCLocker may not be active but the GCLocker initiated
 996         // GC may not yet have been performed (GCLocker::needs_gc()
 997         // returns true). In this case we do not try this GC and
 998         // wait until the GCLocker initiated GC is performed, and
 999         // then retry the allocation.
1000         if (GCLocker::needs_gc()) {
1001           should_try_gc = false;
1002         } else {
1003           // Read the GC count while still holding the Heap_lock.
1004           gc_count_before = total_collections();
1005           should_try_gc = true;
1006         }
1007       }
1008     }
1009 
1010     if (should_try_gc) {
1011       // If we failed to allocate the humongous object, we should try to
1012       // do a collection pause (if we're allowed) in case it reclaims
1013       // enough space for the allocation to succeed after the pause.
1014 
1015       bool succeeded;
1016       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1017                                    GCCause::_g1_humongous_allocation);
1018       if (result != NULL) {
1019         assert(succeeded, "only way to get back a non-NULL result");
1020         return result;
1021       }
1022 
1023       if (succeeded) {
1024         // If we get here we successfully scheduled a collection which
1025         // failed to allocate. No point in trying to allocate
1026         // further. We'll just return NULL.
1027         MutexLockerEx x(Heap_lock);
1028         *gc_count_before_ret = total_collections();
1029         return NULL;
1030       }
1031     } else {
1032       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1033         MutexLockerEx x(Heap_lock);
1034         *gc_count_before_ret = total_collections();
1035         return NULL;
1036       }
1037       // The GCLocker is either active or the GCLocker initiated
1038       // GC has not yet been performed. Stall until it is and
1039       // then retry the allocation.
1040       GCLocker::stall_until_clear();
1041       (*gclocker_retry_count_ret) += 1;
1042     }
1043 
1044     // We can reach here if we were unsuccessful in scheduling a
1045     // collection (because another thread beat us to it) or if we were
1046     // stalled due to the GC locker. In either can we should retry the
1047     // allocation attempt in case another thread successfully
1048     // performed a collection and reclaimed enough space.  Give a
1049     // warning if we seem to be looping forever.
1050 
1051     if ((QueuedAllocationWarningCount > 0) &&
1052         (try_count % QueuedAllocationWarningCount == 0)) {
1053       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1054                       "retries %d times", try_count);
1055     }
1056   }
1057 
1058   ShouldNotReachHere();
1059   return NULL;
1060 }
1061 
1062 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1063                                                            AllocationContext_t context,
1064                                                            bool expect_null_mutator_alloc_region) {
1065   assert_at_safepoint(true /* should_be_vm_thread */);
1066   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1067          "the current alloc region was unexpectedly found to be non-NULL");
1068 
1069   if (!is_humongous(word_size)) {
1070     return _allocator->attempt_allocation_locked(word_size, context);
1071   } else {
1072     HeapWord* result = humongous_obj_allocate(word_size, context);
1073     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1074       collector_state()->set_initiate_conc_mark_if_possible(true);
1075     }
1076     return result;
1077   }
1078 
1079   ShouldNotReachHere();
1080 }
1081 
1082 class PostCompactionPrinterClosure: public HeapRegionClosure {
1083 private:
1084   G1HRPrinter* _hr_printer;
1085 public:
1086   bool doHeapRegion(HeapRegion* hr) {
1087     assert(!hr->is_young(), "not expecting to find young regions");
1088     _hr_printer->post_compaction(hr);
1089     return false;
1090   }
1091 
1092   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1093     : _hr_printer(hr_printer) { }
1094 };
1095 
1096 void G1CollectedHeap::print_hrm_post_compaction() {
1097   if (_hr_printer.is_active()) {
1098     PostCompactionPrinterClosure cl(hr_printer());
1099     heap_region_iterate(&cl);
1100   }
1101 
1102 }
1103 
1104 void G1CollectedHeap::abort_concurrent_cycle() {
1105   // Note: When we have a more flexible GC logging framework that
1106   // allows us to add optional attributes to a GC log record we
1107   // could consider timing and reporting how long we wait in the
1108   // following two methods.
1109   wait_while_free_regions_coming();
1110   // If we start the compaction before the CM threads finish
1111   // scanning the root regions we might trip them over as we'll
1112   // be moving objects / updating references. So let's wait until
1113   // they are done. By telling them to abort, they should complete
1114   // early.
1115   _cm->root_regions()->abort();
1116   _cm->root_regions()->wait_until_scan_finished();
1117   append_secondary_free_list_if_not_empty_with_lock();
1118 
1119   // Disable discovery and empty the discovered lists
1120   // for the CM ref processor.
1121   ref_processor_cm()->disable_discovery();
1122   ref_processor_cm()->abandon_partial_discovery();
1123   ref_processor_cm()->verify_no_references_recorded();
1124 
1125   // Abandon current iterations of concurrent marking and concurrent
1126   // refinement, if any are in progress.
1127   concurrent_mark()->abort();
1128 }
1129 
1130 void G1CollectedHeap::prepare_heap_for_full_collection() {
1131   // Make sure we'll choose a new allocation region afterwards.
1132   _allocator->release_mutator_alloc_region();
1133   _allocator->abandon_gc_alloc_regions();
1134   g1_rem_set()->cleanupHRRS();
1135 
1136   // We may have added regions to the current incremental collection
1137   // set between the last GC or pause and now. We need to clear the
1138   // incremental collection set and then start rebuilding it afresh
1139   // after this full GC.
1140   abandon_collection_set(collection_set());
1141 
1142   tear_down_region_sets(false /* free_list_only */);
1143   collector_state()->set_gcs_are_young(true);
1144 }
1145 
1146 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1147   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1148   assert(used() == recalculate_used(), "Should be equal");
1149   _verifier->verify_region_sets_optional();
1150   _verifier->verify_before_gc();
1151   _verifier->check_bitmaps("Full GC Start");
1152 }
1153 
1154 void G1CollectedHeap::prepare_heap_for_mutators() {
1155   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1156   ClassLoaderDataGraph::purge();
1157   MetaspaceAux::verify_metrics();
1158 
1159   // Prepare heap for normal collections.
1160   assert(num_free_regions() == 0, "we should not have added any free regions");
1161   rebuild_region_sets(false /* free_list_only */);
1162   abort_refinement();
1163   resize_if_necessary_after_full_collection();
1164 
1165   // Rebuild the strong code root lists for each region
1166   rebuild_strong_code_roots();
1167 
1168   // Start a new incremental collection set for the next pause
1169   start_new_collection_set();
1170 
1171   _allocator->init_mutator_alloc_region();
1172 
1173   // Post collection state updates.
1174   MetaspaceGC::compute_new_size();
1175 }
1176 
1177 void G1CollectedHeap::abort_refinement() {
1178   if (_hot_card_cache->use_cache()) {
1179     _hot_card_cache->reset_card_counts();
1180     _hot_card_cache->reset_hot_cache();
1181   }
1182 
1183   // Discard all remembered set updates.
1184   JavaThread::dirty_card_queue_set().abandon_logs();
1185   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1186 }
1187 
1188 void G1CollectedHeap::verify_after_full_collection() {
1189   check_gc_time_stamps();
1190   _hrm.verify_optional();
1191   _verifier->verify_region_sets_optional();
1192   _verifier->verify_after_gc();
1193   // Clear the previous marking bitmap, if needed for bitmap verification.
1194   // Note we cannot do this when we clear the next marking bitmap in
1195   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1196   // objects marked during a full GC against the previous bitmap.
1197   // But we need to clear it before calling check_bitmaps below since
1198   // the full GC has compacted objects and updated TAMS but not updated
1199   // the prev bitmap.
1200   if (G1VerifyBitmaps) {
1201     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1202     _cm->clear_prev_bitmap(workers());
1203   }
1204   _verifier->check_bitmaps("Full GC End");
1205 
1206   // At this point there should be no regions in the
1207   // entire heap tagged as young.
1208   assert(check_young_list_empty(), "young list should be empty at this point");
1209 
1210   // Note: since we've just done a full GC, concurrent
1211   // marking is no longer active. Therefore we need not
1212   // re-enable reference discovery for the CM ref processor.
1213   // That will be done at the start of the next marking cycle.
1214   // We also know that the STW processor should no longer
1215   // discover any new references.
1216   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1217   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1218   ref_processor_stw()->verify_no_references_recorded();
1219   ref_processor_cm()->verify_no_references_recorded();
1220 }
1221 
1222 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1223   print_hrm_post_compaction();
1224   heap_transition->print();
1225   print_heap_after_gc();
1226   print_heap_regions();
1227 #ifdef TRACESPINNING
1228   ParallelTaskTerminator::print_termination_counts();
1229 #endif
1230 }
1231 
1232 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1233   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1234   g1_policy()->record_full_collection_start();
1235 
1236   print_heap_before_gc();
1237   print_heap_regions();
1238 
1239   abort_concurrent_cycle();
1240   verify_before_full_collection(scope->is_explicit_gc());
1241 
1242   gc_prologue(true);
1243   prepare_heap_for_full_collection();
1244 
1245   {
1246     G1FullCollector collector(scope, ref_processor_stw(), concurrent_mark()->nextMarkBitMap(), workers()->active_workers());
1247     // Prepare collection by putting reference processor
1248     // in a correct state.
1249     collector.prepare_collection();
1250 
1251     // Do the actual collection.
1252     collector.collect();
1253 
1254     collector.complete_collection();
1255   }
1256 
1257   prepare_heap_for_mutators();
1258 
1259   g1_policy()->record_full_collection_end();
1260   gc_epilogue(true);
1261 
1262   // Post collection verification.
1263   verify_after_full_collection();
1264 
1265   // Post collection logging.
1266   // We should do this after we potentially resize the heap so
1267   // that all the COMMIT / UNCOMMIT events are generated before
1268   // the compaction events.
1269   print_heap_after_full_collection(scope->heap_transition());
1270 }
1271 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1272                                          bool clear_all_soft_refs) {
1273   assert_at_safepoint(true /* should_be_vm_thread */);
1274 
1275   if (GCLocker::check_active_before_gc()) {
1276     // Full GC was not completed.
1277     return false;
1278   }
1279 
1280   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1281       collector_policy()->should_clear_all_soft_refs();
1282 
1283   G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
1284   do_full_collection_inner(&scope);
1285 
1286   // Full collection was successfully completed.
1287   return true;
1288 }
1289 
1290 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1291   // Currently, there is no facility in the do_full_collection(bool) API to notify
1292   // the caller that the collection did not succeed (e.g., because it was locked
1293   // out by the GC locker). So, right now, we'll ignore the return value.
1294   bool dummy = do_full_collection(true,                /* explicit_gc */
1295                                   clear_all_soft_refs);
1296 }
1297 
1298 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1299   // Include bytes that will be pre-allocated to support collections, as "used".
1300   const size_t used_after_gc = used();
1301   const size_t capacity_after_gc = capacity();
1302   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1303 
1304   // This is enforced in arguments.cpp.
1305   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1306          "otherwise the code below doesn't make sense");
1307 
1308   // We don't have floating point command-line arguments
1309   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1310   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1311   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1312   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1313 
1314   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1315   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1316 
1317   // We have to be careful here as these two calculations can overflow
1318   // 32-bit size_t's.
1319   double used_after_gc_d = (double) used_after_gc;
1320   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1321   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1322 
1323   // Let's make sure that they are both under the max heap size, which
1324   // by default will make them fit into a size_t.
1325   double desired_capacity_upper_bound = (double) max_heap_size;
1326   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1327                                     desired_capacity_upper_bound);
1328   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1329                                     desired_capacity_upper_bound);
1330 
1331   // We can now safely turn them into size_t's.
1332   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1333   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1334 
1335   // This assert only makes sense here, before we adjust them
1336   // with respect to the min and max heap size.
1337   assert(minimum_desired_capacity <= maximum_desired_capacity,
1338          "minimum_desired_capacity = " SIZE_FORMAT ", "
1339          "maximum_desired_capacity = " SIZE_FORMAT,
1340          minimum_desired_capacity, maximum_desired_capacity);
1341 
1342   // Should not be greater than the heap max size. No need to adjust
1343   // it with respect to the heap min size as it's a lower bound (i.e.,
1344   // we'll try to make the capacity larger than it, not smaller).
1345   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1346   // Should not be less than the heap min size. No need to adjust it
1347   // with respect to the heap max size as it's an upper bound (i.e.,
1348   // we'll try to make the capacity smaller than it, not greater).
1349   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1350 
1351   if (capacity_after_gc < minimum_desired_capacity) {
1352     // Don't expand unless it's significant
1353     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1354 
1355     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1356                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1357                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1358 
1359     expand(expand_bytes, _workers);
1360 
1361     // No expansion, now see if we want to shrink
1362   } else if (capacity_after_gc > maximum_desired_capacity) {
1363     // Capacity too large, compute shrinking size
1364     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1365 
1366     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1367                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1368                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1369 
1370     shrink(shrink_bytes);
1371   }
1372 }
1373 
1374 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1375                                                             AllocationContext_t context,
1376                                                             bool do_gc,
1377                                                             bool clear_all_soft_refs,
1378                                                             bool expect_null_mutator_alloc_region,
1379                                                             bool* gc_succeeded) {
1380   *gc_succeeded = true;
1381   // Let's attempt the allocation first.
1382   HeapWord* result =
1383     attempt_allocation_at_safepoint(word_size,
1384                                     context,
1385                                     expect_null_mutator_alloc_region);
1386   if (result != NULL) {
1387     assert(*gc_succeeded, "sanity");
1388     return result;
1389   }
1390 
1391   // In a G1 heap, we're supposed to keep allocation from failing by
1392   // incremental pauses.  Therefore, at least for now, we'll favor
1393   // expansion over collection.  (This might change in the future if we can
1394   // do something smarter than full collection to satisfy a failed alloc.)
1395   result = expand_and_allocate(word_size, context);
1396   if (result != NULL) {
1397     assert(*gc_succeeded, "sanity");
1398     return result;
1399   }
1400 
1401   if (do_gc) {
1402     // Expansion didn't work, we'll try to do a Full GC.
1403     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1404                                        clear_all_soft_refs);
1405   }
1406 
1407   return NULL;
1408 }
1409 
1410 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1411                                                      AllocationContext_t context,
1412                                                      bool* succeeded) {
1413   assert_at_safepoint(true /* should_be_vm_thread */);
1414 
1415   // Attempts to allocate followed by Full GC.
1416   HeapWord* result =
1417     satisfy_failed_allocation_helper(word_size,
1418                                      context,
1419                                      true,  /* do_gc */
1420                                      false, /* clear_all_soft_refs */
1421                                      false, /* expect_null_mutator_alloc_region */
1422                                      succeeded);
1423 
1424   if (result != NULL || !*succeeded) {
1425     return result;
1426   }
1427 
1428   // Attempts to allocate followed by Full GC that will collect all soft references.
1429   result = satisfy_failed_allocation_helper(word_size,
1430                                             context,
1431                                             true, /* do_gc */
1432                                             true, /* clear_all_soft_refs */
1433                                             true, /* expect_null_mutator_alloc_region */
1434                                             succeeded);
1435 
1436   if (result != NULL || !*succeeded) {
1437     return result;
1438   }
1439 
1440   // Attempts to allocate, no GC
1441   result = satisfy_failed_allocation_helper(word_size,
1442                                             context,
1443                                             false, /* do_gc */
1444                                             false, /* clear_all_soft_refs */
1445                                             true,  /* expect_null_mutator_alloc_region */
1446                                             succeeded);
1447 
1448   if (result != NULL) {
1449     assert(*succeeded, "sanity");
1450     return result;
1451   }
1452 
1453   assert(!collector_policy()->should_clear_all_soft_refs(),
1454          "Flag should have been handled and cleared prior to this point");
1455 
1456   // What else?  We might try synchronous finalization later.  If the total
1457   // space available is large enough for the allocation, then a more
1458   // complete compaction phase than we've tried so far might be
1459   // appropriate.
1460   assert(*succeeded, "sanity");
1461   return NULL;
1462 }
1463 
1464 // Attempting to expand the heap sufficiently
1465 // to support an allocation of the given "word_size".  If
1466 // successful, perform the allocation and return the address of the
1467 // allocated block, or else "NULL".
1468 
1469 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1470   assert_at_safepoint(true /* should_be_vm_thread */);
1471 
1472   _verifier->verify_region_sets_optional();
1473 
1474   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1475   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1476                             word_size * HeapWordSize);
1477 
1478 
1479   if (expand(expand_bytes, _workers)) {
1480     _hrm.verify_optional();
1481     _verifier->verify_region_sets_optional();
1482     return attempt_allocation_at_safepoint(word_size,
1483                                            context,
1484                                            false /* expect_null_mutator_alloc_region */);
1485   }
1486   return NULL;
1487 }
1488 
1489 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1490   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1491   aligned_expand_bytes = align_up(aligned_expand_bytes,
1492                                        HeapRegion::GrainBytes);
1493 
1494   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1495                             expand_bytes, aligned_expand_bytes);
1496 
1497   if (is_maximal_no_gc()) {
1498     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1499     return false;
1500   }
1501 
1502   double expand_heap_start_time_sec = os::elapsedTime();
1503   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1504   assert(regions_to_expand > 0, "Must expand by at least one region");
1505 
1506   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1507   if (expand_time_ms != NULL) {
1508     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1509   }
1510 
1511   if (expanded_by > 0) {
1512     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1513     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1514     g1_policy()->record_new_heap_size(num_regions());
1515   } else {
1516     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1517 
1518     // The expansion of the virtual storage space was unsuccessful.
1519     // Let's see if it was because we ran out of swap.
1520     if (G1ExitOnExpansionFailure &&
1521         _hrm.available() >= regions_to_expand) {
1522       // We had head room...
1523       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1524     }
1525   }
1526   return regions_to_expand > 0;
1527 }
1528 
1529 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1530   size_t aligned_shrink_bytes =
1531     ReservedSpace::page_align_size_down(shrink_bytes);
1532   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1533                                          HeapRegion::GrainBytes);
1534   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1535 
1536   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1537   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1538 
1539 
1540   log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1541                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1542   if (num_regions_removed > 0) {
1543     g1_policy()->record_new_heap_size(num_regions());
1544   } else {
1545     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1546   }
1547 }
1548 
1549 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1550   _verifier->verify_region_sets_optional();
1551 
1552   // We should only reach here at the end of a Full GC which means we
1553   // should not not be holding to any GC alloc regions. The method
1554   // below will make sure of that and do any remaining clean up.
1555   _allocator->abandon_gc_alloc_regions();
1556 
1557   // Instead of tearing down / rebuilding the free lists here, we
1558   // could instead use the remove_all_pending() method on free_list to
1559   // remove only the ones that we need to remove.
1560   tear_down_region_sets(true /* free_list_only */);
1561   shrink_helper(shrink_bytes);
1562   rebuild_region_sets(true /* free_list_only */);
1563 
1564   _hrm.verify_optional();
1565   _verifier->verify_region_sets_optional();
1566 }
1567 
1568 // Public methods.
1569 
1570 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1571   CollectedHeap(),
1572   _collector_policy(collector_policy),
1573   _g1_policy(create_g1_policy()),
1574   _collection_set(this, _g1_policy),
1575   _dirty_card_queue_set(false),
1576   _is_alive_closure_cm(this),
1577   _is_alive_closure_stw(this),
1578   _ref_processor_cm(NULL),
1579   _ref_processor_stw(NULL),
1580   _bot(NULL),
1581   _hot_card_cache(NULL),
1582   _g1_rem_set(NULL),
1583   _cg1r(NULL),
1584   _g1mm(NULL),
1585   _refine_cte_cl(NULL),
1586   _preserved_marks_set(true /* in_c_heap */),
1587   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1588   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1589   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1590   _humongous_reclaim_candidates(),
1591   _has_humongous_reclaim_candidates(false),
1592   _archive_allocator(NULL),
1593   _free_regions_coming(false),
1594   _gc_time_stamp(0),
1595   _summary_bytes_used(0),
1596   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1597   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1598   _expand_heap_after_alloc_failure(true),
1599   _old_marking_cycles_started(0),
1600   _old_marking_cycles_completed(0),
1601   _in_cset_fast_test(),
1602   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1603   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1604 
1605   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1606                           /* are_GC_task_threads */true,
1607                           /* are_ConcurrentGC_threads */false);
1608   _workers->initialize_workers();
1609   _verifier = new G1HeapVerifier(this);
1610 
1611   _allocator = G1Allocator::create_allocator(this);
1612 
1613   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1614 
1615   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1616 
1617   // Override the default _filler_array_max_size so that no humongous filler
1618   // objects are created.
1619   _filler_array_max_size = _humongous_object_threshold_in_words;
1620 
1621   uint n_queues = ParallelGCThreads;
1622   _task_queues = new RefToScanQueueSet(n_queues);
1623 
1624   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1625 
1626   for (uint i = 0; i < n_queues; i++) {
1627     RefToScanQueue* q = new RefToScanQueue();
1628     q->initialize();
1629     _task_queues->register_queue(i, q);
1630     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1631   }
1632 
1633   // Initialize the G1EvacuationFailureALot counters and flags.
1634   NOT_PRODUCT(reset_evacuation_should_fail();)
1635 
1636   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1637 }
1638 
1639 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1640                                                                  size_t size,
1641                                                                  size_t translation_factor) {
1642   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1643   // Allocate a new reserved space, preferring to use large pages.
1644   ReservedSpace rs(size, preferred_page_size);
1645   G1RegionToSpaceMapper* result  =
1646     G1RegionToSpaceMapper::create_mapper(rs,
1647                                          size,
1648                                          rs.alignment(),
1649                                          HeapRegion::GrainBytes,
1650                                          translation_factor,
1651                                          mtGC);
1652 
1653   os::trace_page_sizes_for_requested_size(description,
1654                                           size,
1655                                           preferred_page_size,
1656                                           rs.alignment(),
1657                                           rs.base(),
1658                                           rs.size());
1659 
1660   return result;
1661 }
1662 
1663 jint G1CollectedHeap::initialize_concurrent_refinement() {
1664   _refine_cte_cl = new RefineCardTableEntryClosure();
1665 
1666   jint ecode = JNI_OK;
1667   _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1668   return ecode;
1669 }
1670 
1671 jint G1CollectedHeap::initialize() {
1672   CollectedHeap::pre_initialize();
1673   os::enable_vtime();
1674 
1675   // Necessary to satisfy locking discipline assertions.
1676 
1677   MutexLocker x(Heap_lock);
1678 
1679   // While there are no constraints in the GC code that HeapWordSize
1680   // be any particular value, there are multiple other areas in the
1681   // system which believe this to be true (e.g. oop->object_size in some
1682   // cases incorrectly returns the size in wordSize units rather than
1683   // HeapWordSize).
1684   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1685 
1686   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1687   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1688   size_t heap_alignment = collector_policy()->heap_alignment();
1689 
1690   // Ensure that the sizes are properly aligned.
1691   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1692   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1693   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1694 
1695   // Reserve the maximum.
1696 
1697   // When compressed oops are enabled, the preferred heap base
1698   // is calculated by subtracting the requested size from the
1699   // 32Gb boundary and using the result as the base address for
1700   // heap reservation. If the requested size is not aligned to
1701   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1702   // into the ReservedHeapSpace constructor) then the actual
1703   // base of the reserved heap may end up differing from the
1704   // address that was requested (i.e. the preferred heap base).
1705   // If this happens then we could end up using a non-optimal
1706   // compressed oops mode.
1707 
1708   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1709                                                  heap_alignment);
1710 
1711   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1712 
1713   // Create the barrier set for the entire reserved region.
1714   G1SATBCardTableLoggingModRefBS* bs
1715     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1716   bs->initialize();
1717   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1718   set_barrier_set(bs);
1719 
1720   // Create the hot card cache.
1721   _hot_card_cache = new G1HotCardCache(this);
1722 
1723   // Carve out the G1 part of the heap.
1724   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1725   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1726   G1RegionToSpaceMapper* heap_storage =
1727     G1RegionToSpaceMapper::create_mapper(g1_rs,
1728                                          g1_rs.size(),
1729                                          page_size,
1730                                          HeapRegion::GrainBytes,
1731                                          1,
1732                                          mtJavaHeap);
1733   os::trace_page_sizes("Heap",
1734                        collector_policy()->min_heap_byte_size(),
1735                        max_byte_size,
1736                        page_size,
1737                        heap_rs.base(),
1738                        heap_rs.size());
1739   heap_storage->set_mapping_changed_listener(&_listener);
1740 
1741   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1742   G1RegionToSpaceMapper* bot_storage =
1743     create_aux_memory_mapper("Block Offset Table",
1744                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1745                              G1BlockOffsetTable::heap_map_factor());
1746 
1747   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1748   G1RegionToSpaceMapper* cardtable_storage =
1749     create_aux_memory_mapper("Card Table",
1750                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1751                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1752 
1753   G1RegionToSpaceMapper* card_counts_storage =
1754     create_aux_memory_mapper("Card Counts Table",
1755                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1756                              G1CardCounts::heap_map_factor());
1757 
1758   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1759   G1RegionToSpaceMapper* prev_bitmap_storage =
1760     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1761   G1RegionToSpaceMapper* next_bitmap_storage =
1762     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1763 
1764   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1765   g1_barrier_set()->initialize(cardtable_storage);
1766   // Do later initialization work for concurrent refinement.
1767   _hot_card_cache->initialize(card_counts_storage);
1768 
1769   // 6843694 - ensure that the maximum region index can fit
1770   // in the remembered set structures.
1771   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1772   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1773 
1774   // Also create a G1 rem set.
1775   _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1776   _g1_rem_set->initialize(max_capacity(), max_regions());
1777 
1778   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1779   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1780   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1781             "too many cards per region");
1782 
1783   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1784 
1785   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1786 
1787   {
1788     HeapWord* start = _hrm.reserved().start();
1789     HeapWord* end = _hrm.reserved().end();
1790     size_t granularity = HeapRegion::GrainBytes;
1791 
1792     _in_cset_fast_test.initialize(start, end, granularity);
1793     _humongous_reclaim_candidates.initialize(start, end, granularity);
1794   }
1795 
1796   // Create the G1ConcurrentMark data structure and thread.
1797   // (Must do this late, so that "max_regions" is defined.)
1798   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1799   if (_cm == NULL || !_cm->completed_initialization()) {
1800     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1801     return JNI_ENOMEM;
1802   }
1803   _cmThread = _cm->cmThread();
1804 
1805   // Now expand into the initial heap size.
1806   if (!expand(init_byte_size, _workers)) {
1807     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1808     return JNI_ENOMEM;
1809   }
1810 
1811   // Perform any initialization actions delegated to the policy.
1812   g1_policy()->init(this, &_collection_set);
1813 
1814   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1815                                                SATB_Q_FL_lock,
1816                                                G1SATBProcessCompletedThreshold,
1817                                                Shared_SATB_Q_lock);
1818 
1819   jint ecode = initialize_concurrent_refinement();
1820   if (ecode != JNI_OK) {
1821     return ecode;
1822   }
1823   
1824   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1825                                                 DirtyCardQ_CBL_mon,
1826                                                 DirtyCardQ_FL_lock,
1827                                                 (int)concurrent_g1_refine()->yellow_zone(),
1828                                                 (int)concurrent_g1_refine()->red_zone(),
1829                                                 Shared_DirtyCardQ_lock,
1830                                                 NULL,  // fl_owner
1831                                                 true); // init_free_ids
1832 
1833   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1834                                     DirtyCardQ_CBL_mon,
1835                                     DirtyCardQ_FL_lock,
1836                                     -1, // never trigger processing
1837                                     -1, // no limit on length
1838                                     Shared_DirtyCardQ_lock,
1839                                     &JavaThread::dirty_card_queue_set());
1840 
1841   // Here we allocate the dummy HeapRegion that is required by the
1842   // G1AllocRegion class.
1843   HeapRegion* dummy_region = _hrm.get_dummy_region();
1844 
1845   // We'll re-use the same region whether the alloc region will
1846   // require BOT updates or not and, if it doesn't, then a non-young
1847   // region will complain that it cannot support allocations without
1848   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1849   dummy_region->set_eden();
1850   // Make sure it's full.
1851   dummy_region->set_top(dummy_region->end());
1852   G1AllocRegion::setup(this, dummy_region);
1853 
1854   _allocator->init_mutator_alloc_region();
1855 
1856   // Do create of the monitoring and management support so that
1857   // values in the heap have been properly initialized.
1858   _g1mm = new G1MonitoringSupport(this);
1859 
1860   G1StringDedup::initialize();
1861 
1862   _preserved_marks_set.init(ParallelGCThreads);
1863 
1864   _collection_set.initialize(max_regions());
1865 
1866   return JNI_OK;
1867 }
1868 
1869 void G1CollectedHeap::stop() {
1870   // Stop all concurrent threads. We do this to make sure these threads
1871   // do not continue to execute and access resources (e.g. logging)
1872   // that are destroyed during shutdown.
1873   _cg1r->stop();
1874   _cmThread->stop();
1875   if (G1StringDedup::is_enabled()) {
1876     G1StringDedup::stop();
1877   }
1878 }
1879 
1880 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1881   return HeapRegion::max_region_size();
1882 }
1883 
1884 void G1CollectedHeap::post_initialize() {
1885   ref_processing_init();
1886 }
1887 
1888 void G1CollectedHeap::ref_processing_init() {
1889   // Reference processing in G1 currently works as follows:
1890   //
1891   // * There are two reference processor instances. One is
1892   //   used to record and process discovered references
1893   //   during concurrent marking; the other is used to
1894   //   record and process references during STW pauses
1895   //   (both full and incremental).
1896   // * Both ref processors need to 'span' the entire heap as
1897   //   the regions in the collection set may be dotted around.
1898   //
1899   // * For the concurrent marking ref processor:
1900   //   * Reference discovery is enabled at initial marking.
1901   //   * Reference discovery is disabled and the discovered
1902   //     references processed etc during remarking.
1903   //   * Reference discovery is MT (see below).
1904   //   * Reference discovery requires a barrier (see below).
1905   //   * Reference processing may or may not be MT
1906   //     (depending on the value of ParallelRefProcEnabled
1907   //     and ParallelGCThreads).
1908   //   * A full GC disables reference discovery by the CM
1909   //     ref processor and abandons any entries on it's
1910   //     discovered lists.
1911   //
1912   // * For the STW processor:
1913   //   * Non MT discovery is enabled at the start of a full GC.
1914   //   * Processing and enqueueing during a full GC is non-MT.
1915   //   * During a full GC, references are processed after marking.
1916   //
1917   //   * Discovery (may or may not be MT) is enabled at the start
1918   //     of an incremental evacuation pause.
1919   //   * References are processed near the end of a STW evacuation pause.
1920   //   * For both types of GC:
1921   //     * Discovery is atomic - i.e. not concurrent.
1922   //     * Reference discovery will not need a barrier.
1923 
1924   MemRegion mr = reserved_region();
1925 
1926   // Concurrent Mark ref processor
1927   _ref_processor_cm =
1928     new ReferenceProcessor(mr,    // span
1929                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
1930                                 // mt processing
1931                            ParallelGCThreads,
1932                                 // degree of mt processing
1933                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1934                                 // mt discovery
1935                            MAX2(ParallelGCThreads, ConcGCThreads),
1936                                 // degree of mt discovery
1937                            false,
1938                                 // Reference discovery is not atomic
1939                            &_is_alive_closure_cm);
1940                                 // is alive closure
1941                                 // (for efficiency/performance)
1942 
1943   // STW ref processor
1944   _ref_processor_stw =
1945     new ReferenceProcessor(mr,    // span
1946                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
1947                                 // mt processing
1948                            ParallelGCThreads,
1949                                 // degree of mt processing
1950                            (ParallelGCThreads > 1),
1951                                 // mt discovery
1952                            ParallelGCThreads,
1953                                 // degree of mt discovery
1954                            true,
1955                                 // Reference discovery is atomic
1956                            &_is_alive_closure_stw);
1957                                 // is alive closure
1958                                 // (for efficiency/performance)
1959 }
1960 
1961 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1962   return _collector_policy;
1963 }
1964 
1965 size_t G1CollectedHeap::capacity() const {
1966   return _hrm.length() * HeapRegion::GrainBytes;
1967 }
1968 
1969 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1970   hr->reset_gc_time_stamp();
1971 }
1972 
1973 #ifndef PRODUCT
1974 
1975 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1976 private:
1977   unsigned _gc_time_stamp;
1978   bool _failures;
1979 
1980 public:
1981   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1982     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1983 
1984   virtual bool doHeapRegion(HeapRegion* hr) {
1985     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1986     if (_gc_time_stamp != region_gc_time_stamp) {
1987       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1988                             region_gc_time_stamp, _gc_time_stamp);
1989       _failures = true;
1990     }
1991     return false;
1992   }
1993 
1994   bool failures() { return _failures; }
1995 };
1996 
1997 void G1CollectedHeap::check_gc_time_stamps() {
1998   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1999   heap_region_iterate(&cl);
2000   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2001 }
2002 #endif // PRODUCT
2003 
2004 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2005   _hot_card_cache->drain(cl, worker_i);
2006 }
2007 
2008 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2009   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2010   size_t n_completed_buffers = 0;
2011   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2012     n_completed_buffers++;
2013   }
2014   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2015   dcqs.clear_n_completed_buffers();
2016   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2017 }
2018 
2019 // Computes the sum of the storage used by the various regions.
2020 size_t G1CollectedHeap::used() const {
2021   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2022   if (_archive_allocator != NULL) {
2023     result += _archive_allocator->used();
2024   }
2025   return result;
2026 }
2027 
2028 size_t G1CollectedHeap::used_unlocked() const {
2029   return _summary_bytes_used;
2030 }
2031 
2032 class SumUsedClosure: public HeapRegionClosure {
2033   size_t _used;
2034 public:
2035   SumUsedClosure() : _used(0) {}
2036   bool doHeapRegion(HeapRegion* r) {
2037     _used += r->used();
2038     return false;
2039   }
2040   size_t result() { return _used; }
2041 };
2042 
2043 size_t G1CollectedHeap::recalculate_used() const {
2044   double recalculate_used_start = os::elapsedTime();
2045 
2046   SumUsedClosure blk;
2047   heap_region_iterate(&blk);
2048 
2049   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2050   return blk.result();
2051 }
2052 
2053 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2054   switch (cause) {
2055     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2056     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2057     case GCCause::_update_allocation_context_stats_inc: return true;
2058     case GCCause::_wb_conc_mark:                        return true;
2059     default :                                           return false;
2060   }
2061 }
2062 
2063 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2064   switch (cause) {
2065     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2066     case GCCause::_g1_humongous_allocation: return true;
2067     default:                                return is_user_requested_concurrent_full_gc(cause);
2068   }
2069 }
2070 
2071 #ifndef PRODUCT
2072 void G1CollectedHeap::allocate_dummy_regions() {
2073   // Let's fill up most of the region
2074   size_t word_size = HeapRegion::GrainWords - 1024;
2075   // And as a result the region we'll allocate will be humongous.
2076   guarantee(is_humongous(word_size), "sanity");
2077 
2078   // _filler_array_max_size is set to humongous object threshold
2079   // but temporarily change it to use CollectedHeap::fill_with_object().
2080   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2081 
2082   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2083     // Let's use the existing mechanism for the allocation
2084     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2085                                                  AllocationContext::system());
2086     if (dummy_obj != NULL) {
2087       MemRegion mr(dummy_obj, word_size);
2088       CollectedHeap::fill_with_object(mr);
2089     } else {
2090       // If we can't allocate once, we probably cannot allocate
2091       // again. Let's get out of the loop.
2092       break;
2093     }
2094   }
2095 }
2096 #endif // !PRODUCT
2097 
2098 void G1CollectedHeap::increment_old_marking_cycles_started() {
2099   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2100          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2101          "Wrong marking cycle count (started: %d, completed: %d)",
2102          _old_marking_cycles_started, _old_marking_cycles_completed);
2103 
2104   _old_marking_cycles_started++;
2105 }
2106 
2107 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2108   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2109 
2110   // We assume that if concurrent == true, then the caller is a
2111   // concurrent thread that was joined the Suspendible Thread
2112   // Set. If there's ever a cheap way to check this, we should add an
2113   // assert here.
2114 
2115   // Given that this method is called at the end of a Full GC or of a
2116   // concurrent cycle, and those can be nested (i.e., a Full GC can
2117   // interrupt a concurrent cycle), the number of full collections
2118   // completed should be either one (in the case where there was no
2119   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2120   // behind the number of full collections started.
2121 
2122   // This is the case for the inner caller, i.e. a Full GC.
2123   assert(concurrent ||
2124          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2125          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2126          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2127          "is inconsistent with _old_marking_cycles_completed = %u",
2128          _old_marking_cycles_started, _old_marking_cycles_completed);
2129 
2130   // This is the case for the outer caller, i.e. the concurrent cycle.
2131   assert(!concurrent ||
2132          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2133          "for outer caller (concurrent cycle): "
2134          "_old_marking_cycles_started = %u "
2135          "is inconsistent with _old_marking_cycles_completed = %u",
2136          _old_marking_cycles_started, _old_marking_cycles_completed);
2137 
2138   _old_marking_cycles_completed += 1;
2139 
2140   // We need to clear the "in_progress" flag in the CM thread before
2141   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2142   // is set) so that if a waiter requests another System.gc() it doesn't
2143   // incorrectly see that a marking cycle is still in progress.
2144   if (concurrent) {
2145     _cmThread->set_idle();
2146   }
2147 
2148   // This notify_all() will ensure that a thread that called
2149   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2150   // and it's waiting for a full GC to finish will be woken up. It is
2151   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2152   FullGCCount_lock->notify_all();
2153 }
2154 
2155 void G1CollectedHeap::collect(GCCause::Cause cause) {
2156   assert_heap_not_locked();
2157 
2158   uint gc_count_before;
2159   uint old_marking_count_before;
2160   uint full_gc_count_before;
2161   bool retry_gc;
2162 
2163   do {
2164     retry_gc = false;
2165 
2166     {
2167       MutexLocker ml(Heap_lock);
2168 
2169       // Read the GC count while holding the Heap_lock
2170       gc_count_before = total_collections();
2171       full_gc_count_before = total_full_collections();
2172       old_marking_count_before = _old_marking_cycles_started;
2173     }
2174 
2175     if (should_do_concurrent_full_gc(cause)) {
2176       // Schedule an initial-mark evacuation pause that will start a
2177       // concurrent cycle. We're setting word_size to 0 which means that
2178       // we are not requesting a post-GC allocation.
2179       VM_G1IncCollectionPause op(gc_count_before,
2180                                  0,     /* word_size */
2181                                  true,  /* should_initiate_conc_mark */
2182                                  g1_policy()->max_pause_time_ms(),
2183                                  cause);
2184       op.set_allocation_context(AllocationContext::current());
2185 
2186       VMThread::execute(&op);
2187       if (!op.pause_succeeded()) {
2188         if (old_marking_count_before == _old_marking_cycles_started) {
2189           retry_gc = op.should_retry_gc();
2190         } else {
2191           // A Full GC happened while we were trying to schedule the
2192           // initial-mark GC. No point in starting a new cycle given
2193           // that the whole heap was collected anyway.
2194         }
2195 
2196         if (retry_gc) {
2197           if (GCLocker::is_active_and_needs_gc()) {
2198             GCLocker::stall_until_clear();
2199           }
2200         }
2201       }
2202     } else {
2203       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2204           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2205 
2206         // Schedule a standard evacuation pause. We're setting word_size
2207         // to 0 which means that we are not requesting a post-GC allocation.
2208         VM_G1IncCollectionPause op(gc_count_before,
2209                                    0,     /* word_size */
2210                                    false, /* should_initiate_conc_mark */
2211                                    g1_policy()->max_pause_time_ms(),
2212                                    cause);
2213         VMThread::execute(&op);
2214       } else {
2215         // Schedule a Full GC.
2216         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2217         VMThread::execute(&op);
2218       }
2219     }
2220   } while (retry_gc);
2221 }
2222 
2223 bool G1CollectedHeap::is_in(const void* p) const {
2224   if (_hrm.reserved().contains(p)) {
2225     // Given that we know that p is in the reserved space,
2226     // heap_region_containing() should successfully
2227     // return the containing region.
2228     HeapRegion* hr = heap_region_containing(p);
2229     return hr->is_in(p);
2230   } else {
2231     return false;
2232   }
2233 }
2234 
2235 #ifdef ASSERT
2236 bool G1CollectedHeap::is_in_exact(const void* p) const {
2237   bool contains = reserved_region().contains(p);
2238   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2239   if (contains && available) {
2240     return true;
2241   } else {
2242     return false;
2243   }
2244 }
2245 #endif
2246 
2247 // Iteration functions.
2248 
2249 // Iterates an ObjectClosure over all objects within a HeapRegion.
2250 
2251 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2252   ObjectClosure* _cl;
2253 public:
2254   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2255   bool doHeapRegion(HeapRegion* r) {
2256     if (!r->is_continues_humongous()) {
2257       r->object_iterate(_cl);
2258     }
2259     return false;
2260   }
2261 };
2262 
2263 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2264   IterateObjectClosureRegionClosure blk(cl);
2265   heap_region_iterate(&blk);
2266 }
2267 
2268 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2269   _hrm.iterate(cl);
2270 }
2271 
2272 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2273                                               uint worker_id,
2274                                               HeapRegionClaimerBase *hrclaimer) const {
2275   _hrm.par_iterate(cl, worker_id, hrclaimer);
2276 }
2277 
2278 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2279   _collection_set.iterate(cl);
2280 }
2281 
2282 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2283   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2284 }
2285 
2286 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2287   HeapRegion* hr = heap_region_containing(addr);
2288   return hr->block_start(addr);
2289 }
2290 
2291 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2292   HeapRegion* hr = heap_region_containing(addr);
2293   return hr->block_size(addr);
2294 }
2295 
2296 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2297   HeapRegion* hr = heap_region_containing(addr);
2298   return hr->block_is_obj(addr);
2299 }
2300 
2301 bool G1CollectedHeap::supports_tlab_allocation() const {
2302   return true;
2303 }
2304 
2305 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2306   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2307 }
2308 
2309 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2310   return _eden.length() * HeapRegion::GrainBytes;
2311 }
2312 
2313 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2314 // must be equal to the humongous object limit.
2315 size_t G1CollectedHeap::max_tlab_size() const {
2316   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2317 }
2318 
2319 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2320   AllocationContext_t context = AllocationContext::current();
2321   return _allocator->unsafe_max_tlab_alloc(context);
2322 }
2323 
2324 size_t G1CollectedHeap::max_capacity() const {
2325   return _hrm.reserved().byte_size();
2326 }
2327 
2328 jlong G1CollectedHeap::millis_since_last_gc() {
2329   // See the notes in GenCollectedHeap::millis_since_last_gc()
2330   // for more information about the implementation.
2331   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2332     _g1_policy->collection_pause_end_millis();
2333   if (ret_val < 0) {
2334     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2335       ". returning zero instead.", ret_val);
2336     return 0;
2337   }
2338   return ret_val;
2339 }
2340 
2341 void G1CollectedHeap::prepare_for_verify() {
2342   _verifier->prepare_for_verify();
2343 }
2344 
2345 void G1CollectedHeap::verify(VerifyOption vo) {
2346   _verifier->verify(vo);
2347 }
2348 
2349 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2350   return true;
2351 }
2352 
2353 const char* const* G1CollectedHeap::concurrent_phases() const {
2354   return _cmThread->concurrent_phases();
2355 }
2356 
2357 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2358   return _cmThread->request_concurrent_phase(phase);
2359 }
2360 
2361 class PrintRegionClosure: public HeapRegionClosure {
2362   outputStream* _st;
2363 public:
2364   PrintRegionClosure(outputStream* st) : _st(st) {}
2365   bool doHeapRegion(HeapRegion* r) {
2366     r->print_on(_st);
2367     return false;
2368   }
2369 };
2370 
2371 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2372                                        const HeapRegion* hr,
2373                                        const VerifyOption vo) const {
2374   switch (vo) {
2375   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2376   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2377   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2378   default:                            ShouldNotReachHere();
2379   }
2380   return false; // keep some compilers happy
2381 }
2382 
2383 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2384                                        const VerifyOption vo) const {
2385   switch (vo) {
2386   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2387   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2388   case VerifyOption_G1UseMarkWord: {
2389     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2390     return !obj->is_gc_marked() && !hr->is_archive();
2391   }
2392   default:                            ShouldNotReachHere();
2393   }
2394   return false; // keep some compilers happy
2395 }
2396 
2397 void G1CollectedHeap::print_heap_regions() const {
2398   Log(gc, heap, region) log;
2399   if (log.is_trace()) {
2400     ResourceMark rm;
2401     print_regions_on(log.trace_stream());
2402   }
2403 }
2404 
2405 void G1CollectedHeap::print_on(outputStream* st) const {
2406   st->print(" %-20s", "garbage-first heap");
2407   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2408             capacity()/K, used_unlocked()/K);
2409   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2410             p2i(_hrm.reserved().start()),
2411             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2412             p2i(_hrm.reserved().end()));
2413   st->cr();
2414   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2415   uint young_regions = young_regions_count();
2416   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2417             (size_t) young_regions * HeapRegion::GrainBytes / K);
2418   uint survivor_regions = survivor_regions_count();
2419   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2420             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2421   st->cr();
2422   MetaspaceAux::print_on(st);
2423 }
2424 
2425 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2426   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2427                "HS=humongous(starts), HC=humongous(continues), "
2428                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2429                "AC=allocation context, "
2430                "TAMS=top-at-mark-start (previous, next)");
2431   PrintRegionClosure blk(st);
2432   heap_region_iterate(&blk);
2433 }
2434 
2435 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2436   print_on(st);
2437 
2438   // Print the per-region information.
2439   print_regions_on(st);
2440 }
2441 
2442 void G1CollectedHeap::print_on_error(outputStream* st) const {
2443   this->CollectedHeap::print_on_error(st);
2444 
2445   if (_cm != NULL) {
2446     st->cr();
2447     _cm->print_on_error(st);
2448   }
2449 }
2450 
2451 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2452   workers()->print_worker_threads_on(st);
2453   _cmThread->print_on(st);
2454   st->cr();
2455   _cm->print_worker_threads_on(st);
2456   _cg1r->print_worker_threads_on(st); // also prints the sample thread
2457   if (G1StringDedup::is_enabled()) {
2458     G1StringDedup::print_worker_threads_on(st);
2459   }
2460 }
2461 
2462 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2463   workers()->threads_do(tc);
2464   tc->do_thread(_cmThread);
2465   _cm->threads_do(tc);
2466   _cg1r->threads_do(tc); // also iterates over the sample thread
2467   if (G1StringDedup::is_enabled()) {
2468     G1StringDedup::threads_do(tc);
2469   }
2470 }
2471 
2472 void G1CollectedHeap::print_tracing_info() const {
2473   g1_rem_set()->print_summary_info();
2474   concurrent_mark()->print_summary_info();
2475 }
2476 
2477 #ifndef PRODUCT
2478 // Helpful for debugging RSet issues.
2479 
2480 class PrintRSetsClosure : public HeapRegionClosure {
2481 private:
2482   const char* _msg;
2483   size_t _occupied_sum;
2484 
2485 public:
2486   bool doHeapRegion(HeapRegion* r) {
2487     HeapRegionRemSet* hrrs = r->rem_set();
2488     size_t occupied = hrrs->occupied();
2489     _occupied_sum += occupied;
2490 
2491     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2492     if (occupied == 0) {
2493       tty->print_cr("  RSet is empty");
2494     } else {
2495       hrrs->print();
2496     }
2497     tty->print_cr("----------");
2498     return false;
2499   }
2500 
2501   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2502     tty->cr();
2503     tty->print_cr("========================================");
2504     tty->print_cr("%s", msg);
2505     tty->cr();
2506   }
2507 
2508   ~PrintRSetsClosure() {
2509     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2510     tty->print_cr("========================================");
2511     tty->cr();
2512   }
2513 };
2514 
2515 void G1CollectedHeap::print_cset_rsets() {
2516   PrintRSetsClosure cl("Printing CSet RSets");
2517   collection_set_iterate(&cl);
2518 }
2519 
2520 void G1CollectedHeap::print_all_rsets() {
2521   PrintRSetsClosure cl("Printing All RSets");;
2522   heap_region_iterate(&cl);
2523 }
2524 #endif // PRODUCT
2525 
2526 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2527 
2528   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2529   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2530   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2531 
2532   size_t eden_capacity_bytes =
2533     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2534 
2535   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2536   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2537                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2538 }
2539 
2540 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2541   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2542                        stats->unused(), stats->used(), stats->region_end_waste(),
2543                        stats->regions_filled(), stats->direct_allocated(),
2544                        stats->failure_used(), stats->failure_waste());
2545 }
2546 
2547 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2548   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2549   gc_tracer->report_gc_heap_summary(when, heap_summary);
2550 
2551   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2552   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2553 }
2554 
2555 G1CollectedHeap* G1CollectedHeap::heap() {
2556   CollectedHeap* heap = Universe::heap();
2557   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2558   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2559   return (G1CollectedHeap*)heap;
2560 }
2561 
2562 void G1CollectedHeap::gc_prologue(bool full) {
2563   // always_do_update_barrier = false;
2564   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2565 
2566   // This summary needs to be printed before incrementing total collections.
2567   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2568 
2569   // Update common counters.
2570   increment_total_collections(full /* full gc */);
2571   if (full) {
2572     increment_old_marking_cycles_started();
2573     reset_gc_time_stamp();
2574   } else {
2575     increment_gc_time_stamp();
2576   }
2577 
2578   // Fill TLAB's and such
2579   double start = os::elapsedTime();
2580   accumulate_statistics_all_tlabs();
2581   ensure_parsability(true);
2582   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2583 }
2584 
2585 void G1CollectedHeap::gc_epilogue(bool full) {
2586   // Update common counters.
2587   if (full) {
2588     // Update the number of full collections that have been completed.
2589     increment_old_marking_cycles_completed(false /* concurrent */);
2590   }
2591 
2592   // We are at the end of the GC. Total collections has already been increased.
2593   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2594 
2595   // FIXME: what is this about?
2596   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2597   // is set.
2598 #if defined(COMPILER2) || INCLUDE_JVMCI
2599   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2600 #endif
2601   // always_do_update_barrier = true;
2602 
2603   double start = os::elapsedTime();
2604   resize_all_tlabs();
2605   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2606 
2607   allocation_context_stats().update(full);
2608 
2609   MemoryService::track_memory_usage();
2610   // We have just completed a GC. Update the soft reference
2611   // policy with the new heap occupancy
2612   Universe::update_heap_info_at_gc();
2613 }
2614 
2615 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2616                                                uint gc_count_before,
2617                                                bool* succeeded,
2618                                                GCCause::Cause gc_cause) {
2619   assert_heap_not_locked_and_not_at_safepoint();
2620   VM_G1IncCollectionPause op(gc_count_before,
2621                              word_size,
2622                              false, /* should_initiate_conc_mark */
2623                              g1_policy()->max_pause_time_ms(),
2624                              gc_cause);
2625 
2626   op.set_allocation_context(AllocationContext::current());
2627   VMThread::execute(&op);
2628 
2629   HeapWord* result = op.result();
2630   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2631   assert(result == NULL || ret_succeeded,
2632          "the result should be NULL if the VM did not succeed");
2633   *succeeded = ret_succeeded;
2634 
2635   assert_heap_not_locked();
2636   return result;
2637 }
2638 
2639 void
2640 G1CollectedHeap::doConcurrentMark() {
2641   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2642   if (!_cmThread->in_progress()) {
2643     _cmThread->set_started();
2644     CGC_lock->notify();
2645   }
2646 }
2647 
2648 size_t G1CollectedHeap::pending_card_num() {
2649   size_t extra_cards = 0;
2650   JavaThread *curr = Threads::first();
2651   while (curr != NULL) {
2652     DirtyCardQueue& dcq = curr->dirty_card_queue();
2653     extra_cards += dcq.size();
2654     curr = curr->next();
2655   }
2656   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2657   size_t buffer_size = dcqs.buffer_size();
2658   size_t buffer_num = dcqs.completed_buffers_num();
2659 
2660   return buffer_size * buffer_num + extra_cards;
2661 }
2662 
2663 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2664  private:
2665   size_t _total_humongous;
2666   size_t _candidate_humongous;
2667 
2668   DirtyCardQueue _dcq;
2669 
2670   // We don't nominate objects with many remembered set entries, on
2671   // the assumption that such objects are likely still live.
2672   bool is_remset_small(HeapRegion* region) const {
2673     HeapRegionRemSet* const rset = region->rem_set();
2674     return G1EagerReclaimHumongousObjectsWithStaleRefs
2675       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2676       : rset->is_empty();
2677   }
2678 
2679   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2680     assert(region->is_starts_humongous(), "Must start a humongous object");
2681 
2682     oop obj = oop(region->bottom());
2683 
2684     // Dead objects cannot be eager reclaim candidates. Due to class
2685     // unloading it is unsafe to query their classes so we return early.
2686     if (heap->is_obj_dead(obj, region)) {
2687       return false;
2688     }
2689 
2690     // Candidate selection must satisfy the following constraints
2691     // while concurrent marking is in progress:
2692     //
2693     // * In order to maintain SATB invariants, an object must not be
2694     // reclaimed if it was allocated before the start of marking and
2695     // has not had its references scanned.  Such an object must have
2696     // its references (including type metadata) scanned to ensure no
2697     // live objects are missed by the marking process.  Objects
2698     // allocated after the start of concurrent marking don't need to
2699     // be scanned.
2700     //
2701     // * An object must not be reclaimed if it is on the concurrent
2702     // mark stack.  Objects allocated after the start of concurrent
2703     // marking are never pushed on the mark stack.
2704     //
2705     // Nominating only objects allocated after the start of concurrent
2706     // marking is sufficient to meet both constraints.  This may miss
2707     // some objects that satisfy the constraints, but the marking data
2708     // structures don't support efficiently performing the needed
2709     // additional tests or scrubbing of the mark stack.
2710     //
2711     // However, we presently only nominate is_typeArray() objects.
2712     // A humongous object containing references induces remembered
2713     // set entries on other regions.  In order to reclaim such an
2714     // object, those remembered sets would need to be cleaned up.
2715     //
2716     // We also treat is_typeArray() objects specially, allowing them
2717     // to be reclaimed even if allocated before the start of
2718     // concurrent mark.  For this we rely on mark stack insertion to
2719     // exclude is_typeArray() objects, preventing reclaiming an object
2720     // that is in the mark stack.  We also rely on the metadata for
2721     // such objects to be built-in and so ensured to be kept live.
2722     // Frequent allocation and drop of large binary blobs is an
2723     // important use case for eager reclaim, and this special handling
2724     // may reduce needed headroom.
2725 
2726     return obj->is_typeArray() && is_remset_small(region);
2727   }
2728 
2729  public:
2730   RegisterHumongousWithInCSetFastTestClosure()
2731   : _total_humongous(0),
2732     _candidate_humongous(0),
2733     _dcq(&JavaThread::dirty_card_queue_set()) {
2734   }
2735 
2736   virtual bool doHeapRegion(HeapRegion* r) {
2737     if (!r->is_starts_humongous()) {
2738       return false;
2739     }
2740     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2741 
2742     bool is_candidate = humongous_region_is_candidate(g1h, r);
2743     uint rindex = r->hrm_index();
2744     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2745     if (is_candidate) {
2746       _candidate_humongous++;
2747       g1h->register_humongous_region_with_cset(rindex);
2748       // Is_candidate already filters out humongous object with large remembered sets.
2749       // If we have a humongous object with a few remembered sets, we simply flush these
2750       // remembered set entries into the DCQS. That will result in automatic
2751       // re-evaluation of their remembered set entries during the following evacuation
2752       // phase.
2753       if (!r->rem_set()->is_empty()) {
2754         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2755                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2756         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2757         HeapRegionRemSetIterator hrrs(r->rem_set());
2758         size_t card_index;
2759         while (hrrs.has_next(card_index)) {
2760           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2761           // The remembered set might contain references to already freed
2762           // regions. Filter out such entries to avoid failing card table
2763           // verification.
2764           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2765             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2766               *card_ptr = CardTableModRefBS::dirty_card_val();
2767               _dcq.enqueue(card_ptr);
2768             }
2769           }
2770         }
2771         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2772                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2773                hrrs.n_yielded(), r->rem_set()->occupied());
2774         r->rem_set()->clear_locked();
2775       }
2776       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2777     }
2778     _total_humongous++;
2779 
2780     return false;
2781   }
2782 
2783   size_t total_humongous() const { return _total_humongous; }
2784   size_t candidate_humongous() const { return _candidate_humongous; }
2785 
2786   void flush_rem_set_entries() { _dcq.flush(); }
2787 };
2788 
2789 void G1CollectedHeap::register_humongous_regions_with_cset() {
2790   if (!G1EagerReclaimHumongousObjects) {
2791     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2792     return;
2793   }
2794   double time = os::elapsed_counter();
2795 
2796   // Collect reclaim candidate information and register candidates with cset.
2797   RegisterHumongousWithInCSetFastTestClosure cl;
2798   heap_region_iterate(&cl);
2799 
2800   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2801   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2802                                                                   cl.total_humongous(),
2803                                                                   cl.candidate_humongous());
2804   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2805 
2806   // Finally flush all remembered set entries to re-check into the global DCQS.
2807   cl.flush_rem_set_entries();
2808 }
2809 
2810 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2811   public:
2812     bool doHeapRegion(HeapRegion* hr) {
2813       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2814         hr->verify_rem_set();
2815       }
2816       return false;
2817     }
2818 };
2819 
2820 uint G1CollectedHeap::num_task_queues() const {
2821   return _task_queues->size();
2822 }
2823 
2824 #if TASKQUEUE_STATS
2825 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2826   st->print_raw_cr("GC Task Stats");
2827   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2828   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2829 }
2830 
2831 void G1CollectedHeap::print_taskqueue_stats() const {
2832   if (!log_is_enabled(Trace, gc, task, stats)) {
2833     return;
2834   }
2835   Log(gc, task, stats) log;
2836   ResourceMark rm;
2837   outputStream* st = log.trace_stream();
2838 
2839   print_taskqueue_stats_hdr(st);
2840 
2841   TaskQueueStats totals;
2842   const uint n = num_task_queues();
2843   for (uint i = 0; i < n; ++i) {
2844     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2845     totals += task_queue(i)->stats;
2846   }
2847   st->print_raw("tot "); totals.print(st); st->cr();
2848 
2849   DEBUG_ONLY(totals.verify());
2850 }
2851 
2852 void G1CollectedHeap::reset_taskqueue_stats() {
2853   const uint n = num_task_queues();
2854   for (uint i = 0; i < n; ++i) {
2855     task_queue(i)->stats.reset();
2856   }
2857 }
2858 #endif // TASKQUEUE_STATS
2859 
2860 void G1CollectedHeap::wait_for_root_region_scanning() {
2861   double scan_wait_start = os::elapsedTime();
2862   // We have to wait until the CM threads finish scanning the
2863   // root regions as it's the only way to ensure that all the
2864   // objects on them have been correctly scanned before we start
2865   // moving them during the GC.
2866   bool waited = _cm->root_regions()->wait_until_scan_finished();
2867   double wait_time_ms = 0.0;
2868   if (waited) {
2869     double scan_wait_end = os::elapsedTime();
2870     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2871   }
2872   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2873 }
2874 
2875 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2876 private:
2877   G1HRPrinter* _hr_printer;
2878 public:
2879   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2880 
2881   virtual bool doHeapRegion(HeapRegion* r) {
2882     _hr_printer->cset(r);
2883     return false;
2884   }
2885 };
2886 
2887 void G1CollectedHeap::start_new_collection_set() {
2888   collection_set()->start_incremental_building();
2889 
2890   clear_cset_fast_test();
2891 
2892   guarantee(_eden.length() == 0, "eden should have been cleared");
2893   g1_policy()->transfer_survivors_to_cset(survivor());
2894 }
2895 
2896 bool
2897 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2898   assert_at_safepoint(true /* should_be_vm_thread */);
2899   guarantee(!is_gc_active(), "collection is not reentrant");
2900 
2901   if (GCLocker::check_active_before_gc()) {
2902     return false;
2903   }
2904 
2905   _gc_timer_stw->register_gc_start();
2906 
2907   GCIdMark gc_id_mark;
2908   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2909 
2910   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2911   ResourceMark rm;
2912 
2913   g1_policy()->note_gc_start();
2914 
2915   wait_for_root_region_scanning();
2916 
2917   print_heap_before_gc();
2918   print_heap_regions();
2919   trace_heap_before_gc(_gc_tracer_stw);
2920 
2921   _verifier->verify_region_sets_optional();
2922   _verifier->verify_dirty_young_regions();
2923 
2924   // We should not be doing initial mark unless the conc mark thread is running
2925   if (!_cmThread->should_terminate()) {
2926     // This call will decide whether this pause is an initial-mark
2927     // pause. If it is, during_initial_mark_pause() will return true
2928     // for the duration of this pause.
2929     g1_policy()->decide_on_conc_mark_initiation();
2930   }
2931 
2932   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2933   assert(!collector_state()->during_initial_mark_pause() ||
2934           collector_state()->gcs_are_young(), "sanity");
2935 
2936   // We also do not allow mixed GCs during marking.
2937   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2938 
2939   // Record whether this pause is an initial mark. When the current
2940   // thread has completed its logging output and it's safe to signal
2941   // the CM thread, the flag's value in the policy has been reset.
2942   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2943 
2944   // Inner scope for scope based logging, timers, and stats collection
2945   {
2946     EvacuationInfo evacuation_info;
2947 
2948     if (collector_state()->during_initial_mark_pause()) {
2949       // We are about to start a marking cycle, so we increment the
2950       // full collection counter.
2951       increment_old_marking_cycles_started();
2952       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2953     }
2954 
2955     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2956 
2957     GCTraceCPUTime tcpu;
2958 
2959     FormatBuffer<> gc_string("Pause ");
2960     if (collector_state()->during_initial_mark_pause()) {
2961       gc_string.append("Initial Mark");
2962     } else if (collector_state()->gcs_are_young()) {
2963       gc_string.append("Young");
2964     } else {
2965       gc_string.append("Mixed");
2966     }
2967     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2968 
2969     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2970                                                                   workers()->active_workers(),
2971                                                                   Threads::number_of_non_daemon_threads());
2972     workers()->update_active_workers(active_workers);
2973     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2974 
2975     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2976     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2977 
2978     // If the secondary_free_list is not empty, append it to the
2979     // free_list. No need to wait for the cleanup operation to finish;
2980     // the region allocation code will check the secondary_free_list
2981     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2982     // set, skip this step so that the region allocation code has to
2983     // get entries from the secondary_free_list.
2984     if (!G1StressConcRegionFreeing) {
2985       append_secondary_free_list_if_not_empty_with_lock();
2986     }
2987 
2988     G1HeapTransition heap_transition(this);
2989     size_t heap_used_bytes_before_gc = used();
2990 
2991     // Don't dynamically change the number of GC threads this early.  A value of
2992     // 0 is used to indicate serial work.  When parallel work is done,
2993     // it will be set.
2994 
2995     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2996       IsGCActiveMark x;
2997 
2998       gc_prologue(false);
2999 
3000       if (VerifyRememberedSets) {
3001         log_info(gc, verify)("[Verifying RemSets before GC]");
3002         VerifyRegionRemSetClosure v_cl;
3003         heap_region_iterate(&v_cl);
3004       }
3005 
3006       _verifier->verify_before_gc();
3007 
3008       _verifier->check_bitmaps("GC Start");
3009 
3010 #if defined(COMPILER2) || INCLUDE_JVMCI
3011       DerivedPointerTable::clear();
3012 #endif
3013 
3014       // Please see comment in g1CollectedHeap.hpp and
3015       // G1CollectedHeap::ref_processing_init() to see how
3016       // reference processing currently works in G1.
3017 
3018       // Enable discovery in the STW reference processor
3019       if (g1_policy()->should_process_references()) {
3020         ref_processor_stw()->enable_discovery();
3021       } else {
3022         ref_processor_stw()->disable_discovery();
3023       }
3024 
3025       {
3026         // We want to temporarily turn off discovery by the
3027         // CM ref processor, if necessary, and turn it back on
3028         // on again later if we do. Using a scoped
3029         // NoRefDiscovery object will do this.
3030         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3031 
3032         // Forget the current alloc region (we might even choose it to be part
3033         // of the collection set!).
3034         _allocator->release_mutator_alloc_region();
3035 
3036         // This timing is only used by the ergonomics to handle our pause target.
3037         // It is unclear why this should not include the full pause. We will
3038         // investigate this in CR 7178365.
3039         //
3040         // Preserving the old comment here if that helps the investigation:
3041         //
3042         // The elapsed time induced by the start time below deliberately elides
3043         // the possible verification above.
3044         double sample_start_time_sec = os::elapsedTime();
3045 
3046         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3047 
3048         if (collector_state()->during_initial_mark_pause()) {
3049           concurrent_mark()->checkpointRootsInitialPre();
3050         }
3051 
3052         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3053 
3054         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3055 
3056         // Make sure the remembered sets are up to date. This needs to be
3057         // done before register_humongous_regions_with_cset(), because the
3058         // remembered sets are used there to choose eager reclaim candidates.
3059         // If the remembered sets are not up to date we might miss some
3060         // entries that need to be handled.
3061         g1_rem_set()->cleanupHRRS();
3062 
3063         register_humongous_regions_with_cset();
3064 
3065         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3066 
3067         // We call this after finalize_cset() to
3068         // ensure that the CSet has been finalized.
3069         _cm->verify_no_cset_oops();
3070 
3071         if (_hr_printer.is_active()) {
3072           G1PrintCollectionSetClosure cl(&_hr_printer);
3073           _collection_set.iterate(&cl);
3074         }
3075 
3076         // Initialize the GC alloc regions.
3077         _allocator->init_gc_alloc_regions(evacuation_info);
3078 
3079         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3080         pre_evacuate_collection_set();
3081 
3082         // Actually do the work...
3083         evacuate_collection_set(evacuation_info, &per_thread_states);
3084 
3085         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3086 
3087         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3088         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3089 
3090         eagerly_reclaim_humongous_regions();
3091 
3092         record_obj_copy_mem_stats();
3093         _survivor_evac_stats.adjust_desired_plab_sz();
3094         _old_evac_stats.adjust_desired_plab_sz();
3095 
3096         double start = os::elapsedTime();
3097         start_new_collection_set();
3098         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3099 
3100         if (evacuation_failed()) {
3101           set_used(recalculate_used());
3102           if (_archive_allocator != NULL) {
3103             _archive_allocator->clear_used();
3104           }
3105           for (uint i = 0; i < ParallelGCThreads; i++) {
3106             if (_evacuation_failed_info_array[i].has_failed()) {
3107               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3108             }
3109           }
3110         } else {
3111           // The "used" of the the collection set have already been subtracted
3112           // when they were freed.  Add in the bytes evacuated.
3113           increase_used(g1_policy()->bytes_copied_during_gc());
3114         }
3115 
3116         if (collector_state()->during_initial_mark_pause()) {
3117           // We have to do this before we notify the CM threads that
3118           // they can start working to make sure that all the
3119           // appropriate initialization is done on the CM object.
3120           concurrent_mark()->checkpointRootsInitialPost();
3121           collector_state()->set_mark_in_progress(true);
3122           // Note that we don't actually trigger the CM thread at
3123           // this point. We do that later when we're sure that
3124           // the current thread has completed its logging output.
3125         }
3126 
3127         allocate_dummy_regions();
3128 
3129         _allocator->init_mutator_alloc_region();
3130 
3131         {
3132           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3133           if (expand_bytes > 0) {
3134             size_t bytes_before = capacity();
3135             // No need for an ergo logging here,
3136             // expansion_amount() does this when it returns a value > 0.
3137             double expand_ms;
3138             if (!expand(expand_bytes, _workers, &expand_ms)) {
3139               // We failed to expand the heap. Cannot do anything about it.
3140             }
3141             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3142           }
3143         }
3144 
3145         // We redo the verification but now wrt to the new CSet which
3146         // has just got initialized after the previous CSet was freed.
3147         _cm->verify_no_cset_oops();
3148 
3149         // This timing is only used by the ergonomics to handle our pause target.
3150         // It is unclear why this should not include the full pause. We will
3151         // investigate this in CR 7178365.
3152         double sample_end_time_sec = os::elapsedTime();
3153         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3154         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScannedCards);
3155         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3156 
3157         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3158         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3159 
3160         if (VerifyRememberedSets) {
3161           log_info(gc, verify)("[Verifying RemSets after GC]");
3162           VerifyRegionRemSetClosure v_cl;
3163           heap_region_iterate(&v_cl);
3164         }
3165 
3166         _verifier->verify_after_gc();
3167         _verifier->check_bitmaps("GC End");
3168 
3169         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3170         ref_processor_stw()->verify_no_references_recorded();
3171 
3172         // CM reference discovery will be re-enabled if necessary.
3173       }
3174 
3175 #ifdef TRACESPINNING
3176       ParallelTaskTerminator::print_termination_counts();
3177 #endif
3178 
3179       gc_epilogue(false);
3180     }
3181 
3182     // Print the remainder of the GC log output.
3183     if (evacuation_failed()) {
3184       log_info(gc)("To-space exhausted");
3185     }
3186 
3187     g1_policy()->print_phases();
3188     heap_transition.print();
3189 
3190     // It is not yet to safe to tell the concurrent mark to
3191     // start as we have some optional output below. We don't want the
3192     // output from the concurrent mark thread interfering with this
3193     // logging output either.
3194 
3195     _hrm.verify_optional();
3196     _verifier->verify_region_sets_optional();
3197 
3198     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3199     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3200 
3201     print_heap_after_gc();
3202     print_heap_regions();
3203     trace_heap_after_gc(_gc_tracer_stw);
3204 
3205     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3206     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3207     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3208     // before any GC notifications are raised.
3209     g1mm()->update_sizes();
3210 
3211     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3212     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3213     _gc_timer_stw->register_gc_end();
3214     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3215   }
3216   // It should now be safe to tell the concurrent mark thread to start
3217   // without its logging output interfering with the logging output
3218   // that came from the pause.
3219 
3220   if (should_start_conc_mark) {
3221     // CAUTION: after the doConcurrentMark() call below,
3222     // the concurrent marking thread(s) could be running
3223     // concurrently with us. Make sure that anything after
3224     // this point does not assume that we are the only GC thread
3225     // running. Note: of course, the actual marking work will
3226     // not start until the safepoint itself is released in
3227     // SuspendibleThreadSet::desynchronize().
3228     doConcurrentMark();
3229   }
3230 
3231   return true;
3232 }
3233 
3234 void G1CollectedHeap::remove_self_forwarding_pointers() {
3235   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3236   workers()->run_task(&rsfp_task);
3237 }
3238 
3239 void G1CollectedHeap::restore_after_evac_failure() {
3240   double remove_self_forwards_start = os::elapsedTime();
3241 
3242   remove_self_forwarding_pointers();
3243   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3244   _preserved_marks_set.restore(&task_executor);
3245 
3246   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3247 }
3248 
3249 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3250   if (!_evacuation_failed) {
3251     _evacuation_failed = true;
3252   }
3253 
3254   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3255   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3256 }
3257 
3258 bool G1ParEvacuateFollowersClosure::offer_termination() {
3259   G1ParScanThreadState* const pss = par_scan_state();
3260   start_term_time();
3261   const bool res = terminator()->offer_termination();
3262   end_term_time();
3263   return res;
3264 }
3265 
3266 void G1ParEvacuateFollowersClosure::do_void() {
3267   G1ParScanThreadState* const pss = par_scan_state();
3268   pss->trim_queue();
3269   do {
3270     pss->steal_and_trim_queue(queues());
3271   } while (!offer_termination());
3272 }
3273 
3274 class G1ParTask : public AbstractGangTask {
3275 protected:
3276   G1CollectedHeap*         _g1h;
3277   G1ParScanThreadStateSet* _pss;
3278   RefToScanQueueSet*       _queues;
3279   G1RootProcessor*         _root_processor;
3280   ParallelTaskTerminator   _terminator;
3281   uint                     _n_workers;
3282 
3283 public:
3284   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3285     : AbstractGangTask("G1 collection"),
3286       _g1h(g1h),
3287       _pss(per_thread_states),
3288       _queues(task_queues),
3289       _root_processor(root_processor),
3290       _terminator(n_workers, _queues),
3291       _n_workers(n_workers)
3292   {}
3293 
3294   void work(uint worker_id) {
3295     if (worker_id >= _n_workers) return;  // no work needed this round
3296 
3297     double start_sec = os::elapsedTime();
3298     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3299 
3300     {
3301       ResourceMark rm;
3302       HandleMark   hm;
3303 
3304       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3305 
3306       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3307       pss->set_ref_processor(rp);
3308 
3309       double start_strong_roots_sec = os::elapsedTime();
3310 
3311       _root_processor->evacuate_roots(pss->closures(), worker_id);
3312 
3313       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3314       // treating the nmethods visited to act as roots for concurrent marking.
3315       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3316       // objects copied by the current evacuation.
3317       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3318                                                       pss->closures()->weak_codeblobs(),
3319                                                       worker_id);
3320 
3321       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3322 
3323       double term_sec = 0.0;
3324       size_t evac_term_attempts = 0;
3325       {
3326         double start = os::elapsedTime();
3327         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3328         evac.do_void();
3329 
3330         evac_term_attempts = evac.term_attempts();
3331         term_sec = evac.term_time();
3332         double elapsed_sec = os::elapsedTime() - start;
3333         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3334         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3335         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3336       }
3337 
3338       assert(pss->queue_is_empty(), "should be empty");
3339 
3340       if (log_is_enabled(Debug, gc, task, stats)) {
3341         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3342         size_t lab_waste;
3343         size_t lab_undo_waste;
3344         pss->waste(lab_waste, lab_undo_waste);
3345         _g1h->print_termination_stats(worker_id,
3346                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3347                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3348                                       term_sec * 1000.0,                          /* evac term time */
3349                                       evac_term_attempts,                         /* evac term attempts */
3350                                       lab_waste,                                  /* alloc buffer waste */
3351                                       lab_undo_waste                              /* undo waste */
3352                                       );
3353       }
3354 
3355       // Close the inner scope so that the ResourceMark and HandleMark
3356       // destructors are executed here and are included as part of the
3357       // "GC Worker Time".
3358     }
3359     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3360   }
3361 };
3362 
3363 void G1CollectedHeap::print_termination_stats_hdr() {
3364   log_debug(gc, task, stats)("GC Termination Stats");
3365   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3366   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3367   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3368 }
3369 
3370 void G1CollectedHeap::print_termination_stats(uint worker_id,
3371                                               double elapsed_ms,
3372                                               double strong_roots_ms,
3373                                               double term_ms,
3374                                               size_t term_attempts,
3375                                               size_t alloc_buffer_waste,
3376                                               size_t undo_waste) const {
3377   log_debug(gc, task, stats)
3378               ("%3d %9.2f %9.2f %6.2f "
3379                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3380                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3381                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3382                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3383                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3384                alloc_buffer_waste * HeapWordSize / K,
3385                undo_waste * HeapWordSize / K);
3386 }
3387 
3388 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3389 private:
3390   BoolObjectClosure* _is_alive;
3391   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3392 
3393   int _initial_string_table_size;
3394   int _initial_symbol_table_size;
3395 
3396   bool  _process_strings;
3397   int _strings_processed;
3398   int _strings_removed;
3399 
3400   bool  _process_symbols;
3401   int _symbols_processed;
3402   int _symbols_removed;
3403 
3404   bool _process_string_dedup;
3405 
3406 public:
3407   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3408     AbstractGangTask("String/Symbol Unlinking"),
3409     _is_alive(is_alive),
3410     _dedup_closure(is_alive, NULL, false),
3411     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3412     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3413     _process_string_dedup(process_string_dedup) {
3414 
3415     _initial_string_table_size = StringTable::the_table()->table_size();
3416     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3417     if (process_strings) {
3418       StringTable::clear_parallel_claimed_index();
3419     }
3420     if (process_symbols) {
3421       SymbolTable::clear_parallel_claimed_index();
3422     }
3423   }
3424 
3425   ~G1StringAndSymbolCleaningTask() {
3426     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3427               "claim value %d after unlink less than initial string table size %d",
3428               StringTable::parallel_claimed_index(), _initial_string_table_size);
3429     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3430               "claim value %d after unlink less than initial symbol table size %d",
3431               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3432 
3433     log_info(gc, stringtable)(
3434         "Cleaned string and symbol table, "
3435         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3436         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3437         strings_processed(), strings_removed(),
3438         symbols_processed(), symbols_removed());
3439   }
3440 
3441   void work(uint worker_id) {
3442     int strings_processed = 0;
3443     int strings_removed = 0;
3444     int symbols_processed = 0;
3445     int symbols_removed = 0;
3446     if (_process_strings) {
3447       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3448       Atomic::add(strings_processed, &_strings_processed);
3449       Atomic::add(strings_removed, &_strings_removed);
3450     }
3451     if (_process_symbols) {
3452       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3453       Atomic::add(symbols_processed, &_symbols_processed);
3454       Atomic::add(symbols_removed, &_symbols_removed);
3455     }
3456     if (_process_string_dedup) {
3457       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3458     }
3459   }
3460 
3461   size_t strings_processed() const { return (size_t)_strings_processed; }
3462   size_t strings_removed()   const { return (size_t)_strings_removed; }
3463 
3464   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3465   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3466 };
3467 
3468 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3469 private:
3470   static Monitor* _lock;
3471 
3472   BoolObjectClosure* const _is_alive;
3473   const bool               _unloading_occurred;
3474   const uint               _num_workers;
3475 
3476   // Variables used to claim nmethods.
3477   CompiledMethod* _first_nmethod;
3478   volatile CompiledMethod* _claimed_nmethod;
3479 
3480   // The list of nmethods that need to be processed by the second pass.
3481   volatile CompiledMethod* _postponed_list;
3482   volatile uint            _num_entered_barrier;
3483 
3484  public:
3485   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3486       _is_alive(is_alive),
3487       _unloading_occurred(unloading_occurred),
3488       _num_workers(num_workers),
3489       _first_nmethod(NULL),
3490       _claimed_nmethod(NULL),
3491       _postponed_list(NULL),
3492       _num_entered_barrier(0)
3493   {
3494     CompiledMethod::increase_unloading_clock();
3495     // Get first alive nmethod
3496     CompiledMethodIterator iter = CompiledMethodIterator();
3497     if(iter.next_alive()) {
3498       _first_nmethod = iter.method();
3499     }
3500     _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3501   }
3502 
3503   ~G1CodeCacheUnloadingTask() {
3504     CodeCache::verify_clean_inline_caches();
3505 
3506     CodeCache::set_needs_cache_clean(false);
3507     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3508 
3509     CodeCache::verify_icholder_relocations();
3510   }
3511 
3512  private:
3513   void add_to_postponed_list(CompiledMethod* nm) {
3514       CompiledMethod* old;
3515       do {
3516         old = (CompiledMethod*)_postponed_list;
3517         nm->set_unloading_next(old);
3518       } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3519   }
3520 
3521   void clean_nmethod(CompiledMethod* nm) {
3522     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3523 
3524     if (postponed) {
3525       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3526       add_to_postponed_list(nm);
3527     }
3528 
3529     // Mark that this thread has been cleaned/unloaded.
3530     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3531     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3532   }
3533 
3534   void clean_nmethod_postponed(CompiledMethod* nm) {
3535     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3536   }
3537 
3538   static const int MaxClaimNmethods = 16;
3539 
3540   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3541     CompiledMethod* first;
3542     CompiledMethodIterator last;
3543 
3544     do {
3545       *num_claimed_nmethods = 0;
3546 
3547       first = (CompiledMethod*)_claimed_nmethod;
3548       last = CompiledMethodIterator(first);
3549 
3550       if (first != NULL) {
3551 
3552         for (int i = 0; i < MaxClaimNmethods; i++) {
3553           if (!last.next_alive()) {
3554             break;
3555           }
3556           claimed_nmethods[i] = last.method();
3557           (*num_claimed_nmethods)++;
3558         }
3559       }
3560 
3561     } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3562   }
3563 
3564   CompiledMethod* claim_postponed_nmethod() {
3565     CompiledMethod* claim;
3566     CompiledMethod* next;
3567 
3568     do {
3569       claim = (CompiledMethod*)_postponed_list;
3570       if (claim == NULL) {
3571         return NULL;
3572       }
3573 
3574       next = claim->unloading_next();
3575 
3576     } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3577 
3578     return claim;
3579   }
3580 
3581  public:
3582   // Mark that we're done with the first pass of nmethod cleaning.
3583   void barrier_mark(uint worker_id) {
3584     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3585     _num_entered_barrier++;
3586     if (_num_entered_barrier == _num_workers) {
3587       ml.notify_all();
3588     }
3589   }
3590 
3591   // See if we have to wait for the other workers to
3592   // finish their first-pass nmethod cleaning work.
3593   void barrier_wait(uint worker_id) {
3594     if (_num_entered_barrier < _num_workers) {
3595       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3596       while (_num_entered_barrier < _num_workers) {
3597           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3598       }
3599     }
3600   }
3601 
3602   // Cleaning and unloading of nmethods. Some work has to be postponed
3603   // to the second pass, when we know which nmethods survive.
3604   void work_first_pass(uint worker_id) {
3605     // The first nmethods is claimed by the first worker.
3606     if (worker_id == 0 && _first_nmethod != NULL) {
3607       clean_nmethod(_first_nmethod);
3608       _first_nmethod = NULL;
3609     }
3610 
3611     int num_claimed_nmethods;
3612     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3613 
3614     while (true) {
3615       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3616 
3617       if (num_claimed_nmethods == 0) {
3618         break;
3619       }
3620 
3621       for (int i = 0; i < num_claimed_nmethods; i++) {
3622         clean_nmethod(claimed_nmethods[i]);
3623       }
3624     }
3625   }
3626 
3627   void work_second_pass(uint worker_id) {
3628     CompiledMethod* nm;
3629     // Take care of postponed nmethods.
3630     while ((nm = claim_postponed_nmethod()) != NULL) {
3631       clean_nmethod_postponed(nm);
3632     }
3633   }
3634 };
3635 
3636 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3637 
3638 class G1KlassCleaningTask : public StackObj {
3639   BoolObjectClosure*                      _is_alive;
3640   volatile jint                           _clean_klass_tree_claimed;
3641   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3642 
3643  public:
3644   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3645       _is_alive(is_alive),
3646       _clean_klass_tree_claimed(0),
3647       _klass_iterator() {
3648   }
3649 
3650  private:
3651   bool claim_clean_klass_tree_task() {
3652     if (_clean_klass_tree_claimed) {
3653       return false;
3654     }
3655 
3656     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3657   }
3658 
3659   InstanceKlass* claim_next_klass() {
3660     Klass* klass;
3661     do {
3662       klass =_klass_iterator.next_klass();
3663     } while (klass != NULL && !klass->is_instance_klass());
3664 
3665     // this can be null so don't call InstanceKlass::cast
3666     return static_cast<InstanceKlass*>(klass);
3667   }
3668 
3669 public:
3670 
3671   void clean_klass(InstanceKlass* ik) {
3672     ik->clean_weak_instanceklass_links(_is_alive);
3673   }
3674 
3675   void work() {
3676     ResourceMark rm;
3677 
3678     // One worker will clean the subklass/sibling klass tree.
3679     if (claim_clean_klass_tree_task()) {
3680       Klass::clean_subklass_tree(_is_alive);
3681     }
3682 
3683     // All workers will help cleaning the classes,
3684     InstanceKlass* klass;
3685     while ((klass = claim_next_klass()) != NULL) {
3686       clean_klass(klass);
3687     }
3688   }
3689 };
3690 
3691 class G1ResolvedMethodCleaningTask : public StackObj {
3692   BoolObjectClosure* _is_alive;
3693   volatile jint      _resolved_method_task_claimed;
3694 public:
3695   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3696       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3697 
3698   bool claim_resolved_method_task() {
3699     if (_resolved_method_task_claimed) {
3700       return false;
3701     }
3702     return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3703   }
3704 
3705   // These aren't big, one thread can do it all.
3706   void work() {
3707     if (claim_resolved_method_task()) {
3708       ResolvedMethodTable::unlink(_is_alive);
3709     }
3710   }
3711 };
3712 
3713 
3714 // To minimize the remark pause times, the tasks below are done in parallel.
3715 class G1ParallelCleaningTask : public AbstractGangTask {
3716 private:
3717   G1StringAndSymbolCleaningTask _string_symbol_task;
3718   G1CodeCacheUnloadingTask      _code_cache_task;
3719   G1KlassCleaningTask           _klass_cleaning_task;
3720   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3721 
3722 public:
3723   // The constructor is run in the VMThread.
3724   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3725       AbstractGangTask("Parallel Cleaning"),
3726       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3727       _code_cache_task(num_workers, is_alive, unloading_occurred),
3728       _klass_cleaning_task(is_alive),
3729       _resolved_method_cleaning_task(is_alive) {
3730   }
3731 
3732   // The parallel work done by all worker threads.
3733   void work(uint worker_id) {
3734     // Do first pass of code cache cleaning.
3735     _code_cache_task.work_first_pass(worker_id);
3736 
3737     // Let the threads mark that the first pass is done.
3738     _code_cache_task.barrier_mark(worker_id);
3739 
3740     // Clean the Strings and Symbols.
3741     _string_symbol_task.work(worker_id);
3742 
3743     // Clean unreferenced things in the ResolvedMethodTable
3744     _resolved_method_cleaning_task.work();
3745 
3746     // Wait for all workers to finish the first code cache cleaning pass.
3747     _code_cache_task.barrier_wait(worker_id);
3748 
3749     // Do the second code cache cleaning work, which realize on
3750     // the liveness information gathered during the first pass.
3751     _code_cache_task.work_second_pass(worker_id);
3752 
3753     // Clean all klasses that were not unloaded.
3754     _klass_cleaning_task.work();
3755   }
3756 };
3757 
3758 
3759 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3760                                         bool class_unloading_occurred) {
3761   uint n_workers = workers()->active_workers();
3762 
3763   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3764   workers()->run_task(&g1_unlink_task);
3765 }
3766 
3767 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3768                                        bool process_strings,
3769                                        bool process_symbols,
3770                                        bool process_string_dedup) {
3771   if (!process_strings && !process_symbols && !process_string_dedup) {
3772     // Nothing to clean.
3773     return;
3774   }
3775 
3776   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3777   workers()->run_task(&g1_unlink_task);
3778 
3779 }
3780 
3781 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3782  private:
3783   DirtyCardQueueSet* _queue;
3784   G1CollectedHeap* _g1h;
3785  public:
3786   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3787     _queue(queue), _g1h(g1h) { }
3788 
3789   virtual void work(uint worker_id) {
3790     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3791     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3792 
3793     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3794     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3795 
3796     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3797   }
3798 };
3799 
3800 void G1CollectedHeap::redirty_logged_cards() {
3801   double redirty_logged_cards_start = os::elapsedTime();
3802 
3803   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3804   dirty_card_queue_set().reset_for_par_iteration();
3805   workers()->run_task(&redirty_task);
3806 
3807   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3808   dcq.merge_bufferlists(&dirty_card_queue_set());
3809   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3810 
3811   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3812 }
3813 
3814 // Weak Reference Processing support
3815 
3816 // An always "is_alive" closure that is used to preserve referents.
3817 // If the object is non-null then it's alive.  Used in the preservation
3818 // of referent objects that are pointed to by reference objects
3819 // discovered by the CM ref processor.
3820 class G1AlwaysAliveClosure: public BoolObjectClosure {
3821   G1CollectedHeap* _g1;
3822 public:
3823   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3824   bool do_object_b(oop p) {
3825     if (p != NULL) {
3826       return true;
3827     }
3828     return false;
3829   }
3830 };
3831 
3832 bool G1STWIsAliveClosure::do_object_b(oop p) {
3833   // An object is reachable if it is outside the collection set,
3834   // or is inside and copied.
3835   return !_g1->is_in_cset(p) || p->is_forwarded();
3836 }
3837 
3838 // Non Copying Keep Alive closure
3839 class G1KeepAliveClosure: public OopClosure {
3840   G1CollectedHeap* _g1;
3841 public:
3842   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3843   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3844   void do_oop(oop* p) {
3845     oop obj = *p;
3846     assert(obj != NULL, "the caller should have filtered out NULL values");
3847 
3848     const InCSetState cset_state = _g1->in_cset_state(obj);
3849     if (!cset_state.is_in_cset_or_humongous()) {
3850       return;
3851     }
3852     if (cset_state.is_in_cset()) {
3853       assert( obj->is_forwarded(), "invariant" );
3854       *p = obj->forwardee();
3855     } else {
3856       assert(!obj->is_forwarded(), "invariant" );
3857       assert(cset_state.is_humongous(),
3858              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3859       _g1->set_humongous_is_live(obj);
3860     }
3861   }
3862 };
3863 
3864 // Copying Keep Alive closure - can be called from both
3865 // serial and parallel code as long as different worker
3866 // threads utilize different G1ParScanThreadState instances
3867 // and different queues.
3868 
3869 class G1CopyingKeepAliveClosure: public OopClosure {
3870   G1CollectedHeap*         _g1h;
3871   OopClosure*              _copy_non_heap_obj_cl;
3872   G1ParScanThreadState*    _par_scan_state;
3873 
3874 public:
3875   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3876                             OopClosure* non_heap_obj_cl,
3877                             G1ParScanThreadState* pss):
3878     _g1h(g1h),
3879     _copy_non_heap_obj_cl(non_heap_obj_cl),
3880     _par_scan_state(pss)
3881   {}
3882 
3883   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3884   virtual void do_oop(      oop* p) { do_oop_work(p); }
3885 
3886   template <class T> void do_oop_work(T* p) {
3887     oop obj = oopDesc::load_decode_heap_oop(p);
3888 
3889     if (_g1h->is_in_cset_or_humongous(obj)) {
3890       // If the referent object has been forwarded (either copied
3891       // to a new location or to itself in the event of an
3892       // evacuation failure) then we need to update the reference
3893       // field and, if both reference and referent are in the G1
3894       // heap, update the RSet for the referent.
3895       //
3896       // If the referent has not been forwarded then we have to keep
3897       // it alive by policy. Therefore we have copy the referent.
3898       //
3899       // If the reference field is in the G1 heap then we can push
3900       // on the PSS queue. When the queue is drained (after each
3901       // phase of reference processing) the object and it's followers
3902       // will be copied, the reference field set to point to the
3903       // new location, and the RSet updated. Otherwise we need to
3904       // use the the non-heap or metadata closures directly to copy
3905       // the referent object and update the pointer, while avoiding
3906       // updating the RSet.
3907 
3908       if (_g1h->is_in_g1_reserved(p)) {
3909         _par_scan_state->push_on_queue(p);
3910       } else {
3911         assert(!Metaspace::contains((const void*)p),
3912                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3913         _copy_non_heap_obj_cl->do_oop(p);
3914       }
3915     }
3916   }
3917 };
3918 
3919 // Serial drain queue closure. Called as the 'complete_gc'
3920 // closure for each discovered list in some of the
3921 // reference processing phases.
3922 
3923 class G1STWDrainQueueClosure: public VoidClosure {
3924 protected:
3925   G1CollectedHeap* _g1h;
3926   G1ParScanThreadState* _par_scan_state;
3927 
3928   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3929 
3930 public:
3931   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3932     _g1h(g1h),
3933     _par_scan_state(pss)
3934   { }
3935 
3936   void do_void() {
3937     G1ParScanThreadState* const pss = par_scan_state();
3938     pss->trim_queue();
3939   }
3940 };
3941 
3942 // Parallel Reference Processing closures
3943 
3944 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3945 // processing during G1 evacuation pauses.
3946 
3947 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3948 private:
3949   G1CollectedHeap*          _g1h;
3950   G1ParScanThreadStateSet*  _pss;
3951   RefToScanQueueSet*        _queues;
3952   WorkGang*                 _workers;
3953   uint                      _active_workers;
3954 
3955 public:
3956   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3957                            G1ParScanThreadStateSet* per_thread_states,
3958                            WorkGang* workers,
3959                            RefToScanQueueSet *task_queues,
3960                            uint n_workers) :
3961     _g1h(g1h),
3962     _pss(per_thread_states),
3963     _queues(task_queues),
3964     _workers(workers),
3965     _active_workers(n_workers)
3966   {
3967     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3968   }
3969 
3970   // Executes the given task using concurrent marking worker threads.
3971   virtual void execute(ProcessTask& task);
3972   virtual void execute(EnqueueTask& task);
3973 };
3974 
3975 // Gang task for possibly parallel reference processing
3976 
3977 class G1STWRefProcTaskProxy: public AbstractGangTask {
3978   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3979   ProcessTask&     _proc_task;
3980   G1CollectedHeap* _g1h;
3981   G1ParScanThreadStateSet* _pss;
3982   RefToScanQueueSet* _task_queues;
3983   ParallelTaskTerminator* _terminator;
3984 
3985 public:
3986   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3987                         G1CollectedHeap* g1h,
3988                         G1ParScanThreadStateSet* per_thread_states,
3989                         RefToScanQueueSet *task_queues,
3990                         ParallelTaskTerminator* terminator) :
3991     AbstractGangTask("Process reference objects in parallel"),
3992     _proc_task(proc_task),
3993     _g1h(g1h),
3994     _pss(per_thread_states),
3995     _task_queues(task_queues),
3996     _terminator(terminator)
3997   {}
3998 
3999   virtual void work(uint worker_id) {
4000     // The reference processing task executed by a single worker.
4001     ResourceMark rm;
4002     HandleMark   hm;
4003 
4004     G1STWIsAliveClosure is_alive(_g1h);
4005 
4006     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4007     pss->set_ref_processor(NULL);
4008 
4009     // Keep alive closure.
4010     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4011 
4012     // Complete GC closure
4013     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4014 
4015     // Call the reference processing task's work routine.
4016     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4017 
4018     // Note we cannot assert that the refs array is empty here as not all
4019     // of the processing tasks (specifically phase2 - pp2_work) execute
4020     // the complete_gc closure (which ordinarily would drain the queue) so
4021     // the queue may not be empty.
4022   }
4023 };
4024 
4025 // Driver routine for parallel reference processing.
4026 // Creates an instance of the ref processing gang
4027 // task and has the worker threads execute it.
4028 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4029   assert(_workers != NULL, "Need parallel worker threads.");
4030 
4031   ParallelTaskTerminator terminator(_active_workers, _queues);
4032   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4033 
4034   _workers->run_task(&proc_task_proxy);
4035 }
4036 
4037 // Gang task for parallel reference enqueueing.
4038 
4039 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4040   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4041   EnqueueTask& _enq_task;
4042 
4043 public:
4044   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4045     AbstractGangTask("Enqueue reference objects in parallel"),
4046     _enq_task(enq_task)
4047   { }
4048 
4049   virtual void work(uint worker_id) {
4050     _enq_task.work(worker_id);
4051   }
4052 };
4053 
4054 // Driver routine for parallel reference enqueueing.
4055 // Creates an instance of the ref enqueueing gang
4056 // task and has the worker threads execute it.
4057 
4058 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4059   assert(_workers != NULL, "Need parallel worker threads.");
4060 
4061   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4062 
4063   _workers->run_task(&enq_task_proxy);
4064 }
4065 
4066 // End of weak reference support closures
4067 
4068 // Abstract task used to preserve (i.e. copy) any referent objects
4069 // that are in the collection set and are pointed to by reference
4070 // objects discovered by the CM ref processor.
4071 
4072 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4073 protected:
4074   G1CollectedHeap*         _g1h;
4075   G1ParScanThreadStateSet* _pss;
4076   RefToScanQueueSet*       _queues;
4077   ParallelTaskTerminator   _terminator;
4078   uint                     _n_workers;
4079 
4080 public:
4081   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4082     AbstractGangTask("ParPreserveCMReferents"),
4083     _g1h(g1h),
4084     _pss(per_thread_states),
4085     _queues(task_queues),
4086     _terminator(workers, _queues),
4087     _n_workers(workers)
4088   {
4089     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4090   }
4091 
4092   void work(uint worker_id) {
4093     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4094 
4095     ResourceMark rm;
4096     HandleMark   hm;
4097 
4098     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4099     pss->set_ref_processor(NULL);
4100     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4101 
4102     // Is alive closure
4103     G1AlwaysAliveClosure always_alive(_g1h);
4104 
4105     // Copying keep alive closure. Applied to referent objects that need
4106     // to be copied.
4107     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4108 
4109     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4110 
4111     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4112     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4113 
4114     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4115     // So this must be true - but assert just in case someone decides to
4116     // change the worker ids.
4117     assert(worker_id < limit, "sanity");
4118     assert(!rp->discovery_is_atomic(), "check this code");
4119 
4120     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4121     for (uint idx = worker_id; idx < limit; idx += stride) {
4122       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4123 
4124       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4125       while (iter.has_next()) {
4126         // Since discovery is not atomic for the CM ref processor, we
4127         // can see some null referent objects.
4128         iter.load_ptrs(DEBUG_ONLY(true));
4129         oop ref = iter.obj();
4130 
4131         // This will filter nulls.
4132         if (iter.is_referent_alive()) {
4133           iter.make_referent_alive();
4134         }
4135         iter.move_to_next();
4136       }
4137     }
4138 
4139     // Drain the queue - which may cause stealing
4140     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4141     drain_queue.do_void();
4142     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4143     assert(pss->queue_is_empty(), "should be");
4144   }
4145 };
4146 
4147 void G1CollectedHeap::process_weak_jni_handles() {
4148   double ref_proc_start = os::elapsedTime();
4149 
4150   G1STWIsAliveClosure is_alive(this);
4151   G1KeepAliveClosure keep_alive(this);
4152   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4153 
4154   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4155   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4156 }
4157 
4158 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4159   // Any reference objects, in the collection set, that were 'discovered'
4160   // by the CM ref processor should have already been copied (either by
4161   // applying the external root copy closure to the discovered lists, or
4162   // by following an RSet entry).
4163   //
4164   // But some of the referents, that are in the collection set, that these
4165   // reference objects point to may not have been copied: the STW ref
4166   // processor would have seen that the reference object had already
4167   // been 'discovered' and would have skipped discovering the reference,
4168   // but would not have treated the reference object as a regular oop.
4169   // As a result the copy closure would not have been applied to the
4170   // referent object.
4171   //
4172   // We need to explicitly copy these referent objects - the references
4173   // will be processed at the end of remarking.
4174   //
4175   // We also need to do this copying before we process the reference
4176   // objects discovered by the STW ref processor in case one of these
4177   // referents points to another object which is also referenced by an
4178   // object discovered by the STW ref processor.
4179   double preserve_cm_referents_time = 0.0;
4180 
4181   // To avoid spawning task when there is no work to do, check that
4182   // a concurrent cycle is active and that some references have been
4183   // discovered.
4184   if (concurrent_mark()->cmThread()->during_cycle() &&
4185       ref_processor_cm()->has_discovered_references()) {
4186     double preserve_cm_referents_start = os::elapsedTime();
4187     uint no_of_gc_workers = workers()->active_workers();
4188     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4189                                                    per_thread_states,
4190                                                    no_of_gc_workers,
4191                                                    _task_queues);
4192     workers()->run_task(&keep_cm_referents);
4193     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4194   }
4195 
4196   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4197 }
4198 
4199 // Weak Reference processing during an evacuation pause (part 1).
4200 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4201   double ref_proc_start = os::elapsedTime();
4202 
4203   ReferenceProcessor* rp = _ref_processor_stw;
4204   assert(rp->discovery_enabled(), "should have been enabled");
4205 
4206   // Closure to test whether a referent is alive.
4207   G1STWIsAliveClosure is_alive(this);
4208 
4209   // Even when parallel reference processing is enabled, the processing
4210   // of JNI refs is serial and performed serially by the current thread
4211   // rather than by a worker. The following PSS will be used for processing
4212   // JNI refs.
4213 
4214   // Use only a single queue for this PSS.
4215   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4216   pss->set_ref_processor(NULL);
4217   assert(pss->queue_is_empty(), "pre-condition");
4218 
4219   // Keep alive closure.
4220   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4221 
4222   // Serial Complete GC closure
4223   G1STWDrainQueueClosure drain_queue(this, pss);
4224 
4225   // Setup the soft refs policy...
4226   rp->setup_policy(false);
4227 
4228   ReferenceProcessorStats stats;
4229   if (!rp->processing_is_mt()) {
4230     // Serial reference processing...
4231     stats = rp->process_discovered_references(&is_alive,
4232                                               &keep_alive,
4233                                               &drain_queue,
4234                                               NULL,
4235                                               _gc_timer_stw);
4236   } else {
4237     uint no_of_gc_workers = workers()->active_workers();
4238 
4239     // Parallel reference processing
4240     assert(no_of_gc_workers <= rp->max_num_q(),
4241            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4242            no_of_gc_workers,  rp->max_num_q());
4243 
4244     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4245     stats = rp->process_discovered_references(&is_alive,
4246                                               &keep_alive,
4247                                               &drain_queue,
4248                                               &par_task_executor,
4249                                               _gc_timer_stw);
4250   }
4251 
4252   _gc_tracer_stw->report_gc_reference_stats(stats);
4253 
4254   // We have completed copying any necessary live referent objects.
4255   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4256 
4257   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4258   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4259 }
4260 
4261 // Weak Reference processing during an evacuation pause (part 2).
4262 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4263   double ref_enq_start = os::elapsedTime();
4264 
4265   ReferenceProcessor* rp = _ref_processor_stw;
4266   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4267 
4268   // Now enqueue any remaining on the discovered lists on to
4269   // the pending list.
4270   if (!rp->processing_is_mt()) {
4271     // Serial reference processing...
4272     rp->enqueue_discovered_references();
4273   } else {
4274     // Parallel reference enqueueing
4275 
4276     uint n_workers = workers()->active_workers();
4277 
4278     assert(n_workers <= rp->max_num_q(),
4279            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4280            n_workers,  rp->max_num_q());
4281 
4282     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4283     rp->enqueue_discovered_references(&par_task_executor);
4284   }
4285 
4286   rp->verify_no_references_recorded();
4287   assert(!rp->discovery_enabled(), "should have been disabled");
4288 
4289   // FIXME
4290   // CM's reference processing also cleans up the string and symbol tables.
4291   // Should we do that here also? We could, but it is a serial operation
4292   // and could significantly increase the pause time.
4293 
4294   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4295   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4296 }
4297 
4298 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4299   double merge_pss_time_start = os::elapsedTime();
4300   per_thread_states->flush();
4301   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4302 }
4303 
4304 void G1CollectedHeap::pre_evacuate_collection_set() {
4305   _expand_heap_after_alloc_failure = true;
4306   _evacuation_failed = false;
4307 
4308   // Disable the hot card cache.
4309   _hot_card_cache->reset_hot_cache_claimed_index();
4310   _hot_card_cache->set_use_cache(false);
4311 
4312   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4313   _preserved_marks_set.assert_empty();
4314 
4315   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4316 
4317   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4318   if (collector_state()->during_initial_mark_pause()) {
4319     double start_clear_claimed_marks = os::elapsedTime();
4320 
4321     ClassLoaderDataGraph::clear_claimed_marks();
4322 
4323     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4324     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4325   }
4326 }
4327 
4328 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4329   // Should G1EvacuationFailureALot be in effect for this GC?
4330   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4331 
4332   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4333 
4334   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4335 
4336   double start_par_time_sec = os::elapsedTime();
4337   double end_par_time_sec;
4338 
4339   {
4340     const uint n_workers = workers()->active_workers();
4341     G1RootProcessor root_processor(this, n_workers);
4342     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4343 
4344     print_termination_stats_hdr();
4345 
4346     workers()->run_task(&g1_par_task);
4347     end_par_time_sec = os::elapsedTime();
4348 
4349     // Closing the inner scope will execute the destructor
4350     // for the G1RootProcessor object. We record the current
4351     // elapsed time before closing the scope so that time
4352     // taken for the destructor is NOT included in the
4353     // reported parallel time.
4354   }
4355 
4356   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4357   phase_times->record_par_time(par_time_ms);
4358 
4359   double code_root_fixup_time_ms =
4360         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4361   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4362 }
4363 
4364 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4365   // Process any discovered reference objects - we have
4366   // to do this _before_ we retire the GC alloc regions
4367   // as we may have to copy some 'reachable' referent
4368   // objects (and their reachable sub-graphs) that were
4369   // not copied during the pause.
4370   if (g1_policy()->should_process_references()) {
4371     preserve_cm_referents(per_thread_states);
4372     process_discovered_references(per_thread_states);
4373   } else {
4374     ref_processor_stw()->verify_no_references_recorded();
4375     process_weak_jni_handles();
4376   }
4377 
4378   if (G1StringDedup::is_enabled()) {
4379     double fixup_start = os::elapsedTime();
4380 
4381     G1STWIsAliveClosure is_alive(this);
4382     G1KeepAliveClosure keep_alive(this);
4383     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4384 
4385     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4386     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4387   }
4388 
4389   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4390 
4391   if (evacuation_failed()) {
4392     restore_after_evac_failure();
4393 
4394     // Reset the G1EvacuationFailureALot counters and flags
4395     // Note: the values are reset only when an actual
4396     // evacuation failure occurs.
4397     NOT_PRODUCT(reset_evacuation_should_fail();)
4398   }
4399 
4400   _preserved_marks_set.assert_empty();
4401 
4402   // Enqueue any remaining references remaining on the STW
4403   // reference processor's discovered lists. We need to do
4404   // this after the card table is cleaned (and verified) as
4405   // the act of enqueueing entries on to the pending list
4406   // will log these updates (and dirty their associated
4407   // cards). We need these updates logged to update any
4408   // RSets.
4409   if (g1_policy()->should_process_references()) {
4410     enqueue_discovered_references(per_thread_states);
4411   } else {
4412     g1_policy()->phase_times()->record_ref_enq_time(0);
4413   }
4414 
4415   _allocator->release_gc_alloc_regions(evacuation_info);
4416 
4417   merge_per_thread_state_info(per_thread_states);
4418 
4419   // Reset and re-enable the hot card cache.
4420   // Note the counts for the cards in the regions in the
4421   // collection set are reset when the collection set is freed.
4422   _hot_card_cache->reset_hot_cache();
4423   _hot_card_cache->set_use_cache(true);
4424 
4425   purge_code_root_memory();
4426 
4427   redirty_logged_cards();
4428 #if defined(COMPILER2) || INCLUDE_JVMCI
4429   double start = os::elapsedTime();
4430   DerivedPointerTable::update_pointers();
4431   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4432 #endif
4433   g1_policy()->print_age_table();
4434 }
4435 
4436 void G1CollectedHeap::record_obj_copy_mem_stats() {
4437   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4438 
4439   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4440                                                create_g1_evac_summary(&_old_evac_stats));
4441 }
4442 
4443 void G1CollectedHeap::free_region(HeapRegion* hr,
4444                                   FreeRegionList* free_list,
4445                                   bool skip_remset,
4446                                   bool skip_hot_card_cache,
4447                                   bool locked) {
4448   assert(!hr->is_free(), "the region should not be free");
4449   assert(!hr->is_empty(), "the region should not be empty");
4450   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4451   assert(free_list != NULL, "pre-condition");
4452 
4453   if (G1VerifyBitmaps) {
4454     MemRegion mr(hr->bottom(), hr->end());
4455     concurrent_mark()->clearRangePrevBitmap(mr);
4456   }
4457 
4458   // Clear the card counts for this region.
4459   // Note: we only need to do this if the region is not young
4460   // (since we don't refine cards in young regions).
4461   if (!skip_hot_card_cache && !hr->is_young()) {
4462     _hot_card_cache->reset_card_counts(hr);
4463   }
4464   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4465   free_list->add_ordered(hr);
4466 }
4467 
4468 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4469                                             FreeRegionList* free_list,
4470                                             bool skip_remset) {
4471   assert(hr->is_humongous(), "this is only for humongous regions");
4472   assert(free_list != NULL, "pre-condition");
4473   hr->clear_humongous();
4474   free_region(hr, free_list, skip_remset);
4475 }
4476 
4477 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4478                                            const uint humongous_regions_removed) {
4479   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4480     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4481     _old_set.bulk_remove(old_regions_removed);
4482     _humongous_set.bulk_remove(humongous_regions_removed);
4483   }
4484 
4485 }
4486 
4487 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4488   assert(list != NULL, "list can't be null");
4489   if (!list->is_empty()) {
4490     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4491     _hrm.insert_list_into_free_list(list);
4492   }
4493 }
4494 
4495 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4496   decrease_used(bytes);
4497 }
4498 
4499 class G1ParScrubRemSetTask: public AbstractGangTask {
4500 protected:
4501   G1RemSet* _g1rs;
4502   HeapRegionClaimer _hrclaimer;
4503 
4504 public:
4505   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4506     AbstractGangTask("G1 ScrubRS"),
4507     _g1rs(g1_rs),
4508     _hrclaimer(num_workers) {
4509   }
4510 
4511   void work(uint worker_id) {
4512     _g1rs->scrub(worker_id, &_hrclaimer);
4513   }
4514 };
4515 
4516 void G1CollectedHeap::scrub_rem_set() {
4517   uint num_workers = workers()->active_workers();
4518   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4519   workers()->run_task(&g1_par_scrub_rs_task);
4520 }
4521 
4522 class G1FreeCollectionSetTask : public AbstractGangTask {
4523 private:
4524 
4525   // Closure applied to all regions in the collection set to do work that needs to
4526   // be done serially in a single thread.
4527   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4528   private:
4529     EvacuationInfo* _evacuation_info;
4530     const size_t* _surviving_young_words;
4531 
4532     // Bytes used in successfully evacuated regions before the evacuation.
4533     size_t _before_used_bytes;
4534     // Bytes used in unsucessfully evacuated regions before the evacuation
4535     size_t _after_used_bytes;
4536 
4537     size_t _bytes_allocated_in_old_since_last_gc;
4538 
4539     size_t _failure_used_words;
4540     size_t _failure_waste_words;
4541 
4542     FreeRegionList _local_free_list;
4543   public:
4544     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4545       HeapRegionClosure(),
4546       _evacuation_info(evacuation_info),
4547       _surviving_young_words(surviving_young_words),
4548       _before_used_bytes(0),
4549       _after_used_bytes(0),
4550       _bytes_allocated_in_old_since_last_gc(0),
4551       _failure_used_words(0),
4552       _failure_waste_words(0),
4553       _local_free_list("Local Region List for CSet Freeing") {
4554     }
4555 
4556     virtual bool doHeapRegion(HeapRegion* r) {
4557       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4558 
4559       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4560       g1h->clear_in_cset(r);
4561 
4562       if (r->is_young()) {
4563         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4564                "Young index %d is wrong for region %u of type %s with %u young regions",
4565                r->young_index_in_cset(),
4566                r->hrm_index(),
4567                r->get_type_str(),
4568                g1h->collection_set()->young_region_length());
4569         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4570         r->record_surv_words_in_group(words_survived);
4571       }
4572 
4573       if (!r->evacuation_failed()) {
4574         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4575         _before_used_bytes += r->used();
4576         g1h->free_region(r,
4577                          &_local_free_list,
4578                          true, /* skip_remset */
4579                          true, /* skip_hot_card_cache */
4580                          true  /* locked */);
4581       } else {
4582         r->uninstall_surv_rate_group();
4583         r->set_young_index_in_cset(-1);
4584         r->set_evacuation_failed(false);
4585         // When moving a young gen region to old gen, we "allocate" that whole region
4586         // there. This is in addition to any already evacuated objects. Notify the
4587         // policy about that.
4588         // Old gen regions do not cause an additional allocation: both the objects
4589         // still in the region and the ones already moved are accounted for elsewhere.
4590         if (r->is_young()) {
4591           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4592         }
4593         // The region is now considered to be old.
4594         r->set_old();
4595         // Do some allocation statistics accounting. Regions that failed evacuation
4596         // are always made old, so there is no need to update anything in the young
4597         // gen statistics, but we need to update old gen statistics.
4598         size_t used_words = r->marked_bytes() / HeapWordSize;
4599 
4600         _failure_used_words += used_words;
4601         _failure_waste_words += HeapRegion::GrainWords - used_words;
4602 
4603         g1h->old_set_add(r);
4604         _after_used_bytes += r->used();
4605       }
4606       return false;
4607     }
4608 
4609     void complete_work() {
4610       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4611 
4612       _evacuation_info->set_regions_freed(_local_free_list.length());
4613       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4614 
4615       g1h->prepend_to_freelist(&_local_free_list);
4616       g1h->decrement_summary_bytes(_before_used_bytes);
4617 
4618       G1Policy* policy = g1h->g1_policy();
4619       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4620 
4621       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4622     }
4623   };
4624 
4625   G1CollectionSet* _collection_set;
4626   G1SerialFreeCollectionSetClosure _cl;
4627   const size_t* _surviving_young_words;
4628 
4629   size_t _rs_lengths;
4630 
4631   volatile jint _serial_work_claim;
4632 
4633   struct WorkItem {
4634     uint region_idx;
4635     bool is_young;
4636     bool evacuation_failed;
4637 
4638     WorkItem(HeapRegion* r) {
4639       region_idx = r->hrm_index();
4640       is_young = r->is_young();
4641       evacuation_failed = r->evacuation_failed();
4642     }
4643   };
4644 
4645   volatile size_t _parallel_work_claim;
4646   size_t _num_work_items;
4647   WorkItem* _work_items;
4648 
4649   void do_serial_work() {
4650     // Need to grab the lock to be allowed to modify the old region list.
4651     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4652     _collection_set->iterate(&_cl);
4653   }
4654 
4655   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4656     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4657 
4658     HeapRegion* r = g1h->region_at(region_idx);
4659     assert(!g1h->is_on_master_free_list(r), "sanity");
4660 
4661     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4662 
4663     if (!is_young) {
4664       g1h->_hot_card_cache->reset_card_counts(r);
4665     }
4666 
4667     if (!evacuation_failed) {
4668       r->rem_set()->clear_locked();
4669     }
4670   }
4671 
4672   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4673   private:
4674     size_t _cur_idx;
4675     WorkItem* _work_items;
4676   public:
4677     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4678 
4679     virtual bool doHeapRegion(HeapRegion* r) {
4680       _work_items[_cur_idx++] = WorkItem(r);
4681       return false;
4682     }
4683   };
4684 
4685   void prepare_work() {
4686     G1PrepareFreeCollectionSetClosure cl(_work_items);
4687     _collection_set->iterate(&cl);
4688   }
4689 
4690   void complete_work() {
4691     _cl.complete_work();
4692 
4693     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4694     policy->record_max_rs_lengths(_rs_lengths);
4695     policy->cset_regions_freed();
4696   }
4697 public:
4698   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4699     AbstractGangTask("G1 Free Collection Set"),
4700     _cl(evacuation_info, surviving_young_words),
4701     _collection_set(collection_set),
4702     _surviving_young_words(surviving_young_words),
4703     _serial_work_claim(0),
4704     _rs_lengths(0),
4705     _parallel_work_claim(0),
4706     _num_work_items(collection_set->region_length()),
4707     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4708     prepare_work();
4709   }
4710 
4711   ~G1FreeCollectionSetTask() {
4712     complete_work();
4713     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4714   }
4715 
4716   // Chunk size for work distribution. The chosen value has been determined experimentally
4717   // to be a good tradeoff between overhead and achievable parallelism.
4718   static uint chunk_size() { return 32; }
4719 
4720   virtual void work(uint worker_id) {
4721     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4722 
4723     // Claim serial work.
4724     if (_serial_work_claim == 0) {
4725       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4726       if (value == 0) {
4727         double serial_time = os::elapsedTime();
4728         do_serial_work();
4729         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4730       }
4731     }
4732 
4733     // Start parallel work.
4734     double young_time = 0.0;
4735     bool has_young_time = false;
4736     double non_young_time = 0.0;
4737     bool has_non_young_time = false;
4738 
4739     while (true) {
4740       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4741       size_t cur = end - chunk_size();
4742 
4743       if (cur >= _num_work_items) {
4744         break;
4745       }
4746 
4747       double start_time = os::elapsedTime();
4748 
4749       end = MIN2(end, _num_work_items);
4750 
4751       for (; cur < end; cur++) {
4752         bool is_young = _work_items[cur].is_young;
4753 
4754         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4755 
4756         double end_time = os::elapsedTime();
4757         double time_taken = end_time - start_time;
4758         if (is_young) {
4759           young_time += time_taken;
4760           has_young_time = true;
4761         } else {
4762           non_young_time += time_taken;
4763           has_non_young_time = true;
4764         }
4765         start_time = end_time;
4766       }
4767     }
4768 
4769     if (has_young_time) {
4770       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4771     }
4772     if (has_non_young_time) {
4773       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4774     }
4775   }
4776 };
4777 
4778 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4779   _eden.clear();
4780 
4781   double free_cset_start_time = os::elapsedTime();
4782 
4783   {
4784     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4785     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4786 
4787     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4788 
4789     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4790                         cl.name(),
4791                         num_workers,
4792                         _collection_set.region_length());
4793     workers()->run_task(&cl, num_workers);
4794   }
4795   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4796 
4797   collection_set->clear();
4798 }
4799 
4800 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4801  private:
4802   FreeRegionList* _free_region_list;
4803   HeapRegionSet* _proxy_set;
4804   uint _humongous_objects_reclaimed;
4805   uint _humongous_regions_reclaimed;
4806   size_t _freed_bytes;
4807  public:
4808 
4809   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4810     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4811   }
4812 
4813   virtual bool doHeapRegion(HeapRegion* r) {
4814     if (!r->is_starts_humongous()) {
4815       return false;
4816     }
4817 
4818     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4819 
4820     oop obj = (oop)r->bottom();
4821     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4822 
4823     // The following checks whether the humongous object is live are sufficient.
4824     // The main additional check (in addition to having a reference from the roots
4825     // or the young gen) is whether the humongous object has a remembered set entry.
4826     //
4827     // A humongous object cannot be live if there is no remembered set for it
4828     // because:
4829     // - there can be no references from within humongous starts regions referencing
4830     // the object because we never allocate other objects into them.
4831     // (I.e. there are no intra-region references that may be missed by the
4832     // remembered set)
4833     // - as soon there is a remembered set entry to the humongous starts region
4834     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4835     // until the end of a concurrent mark.
4836     //
4837     // It is not required to check whether the object has been found dead by marking
4838     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4839     // all objects allocated during that time are considered live.
4840     // SATB marking is even more conservative than the remembered set.
4841     // So if at this point in the collection there is no remembered set entry,
4842     // nobody has a reference to it.
4843     // At the start of collection we flush all refinement logs, and remembered sets
4844     // are completely up-to-date wrt to references to the humongous object.
4845     //
4846     // Other implementation considerations:
4847     // - never consider object arrays at this time because they would pose
4848     // considerable effort for cleaning up the the remembered sets. This is
4849     // required because stale remembered sets might reference locations that
4850     // are currently allocated into.
4851     uint region_idx = r->hrm_index();
4852     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4853         !r->rem_set()->is_empty()) {
4854       log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT "  with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4855                                region_idx,
4856                                (size_t)obj->size() * HeapWordSize,
4857                                p2i(r->bottom()),
4858                                r->rem_set()->occupied(),
4859                                r->rem_set()->strong_code_roots_list_length(),
4860                                next_bitmap->isMarked(r->bottom()),
4861                                g1h->is_humongous_reclaim_candidate(region_idx),
4862                                obj->is_typeArray()
4863                               );
4864       return false;
4865     }
4866 
4867     guarantee(obj->is_typeArray(),
4868               "Only eagerly reclaiming type arrays is supported, but the object "
4869               PTR_FORMAT " is not.", p2i(r->bottom()));
4870 
4871     log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4872                              region_idx,
4873                              (size_t)obj->size() * HeapWordSize,
4874                              p2i(r->bottom()),
4875                              r->rem_set()->occupied(),
4876                              r->rem_set()->strong_code_roots_list_length(),
4877                              next_bitmap->isMarked(r->bottom()),
4878                              g1h->is_humongous_reclaim_candidate(region_idx),
4879                              obj->is_typeArray()
4880                             );
4881 
4882     // Need to clear mark bit of the humongous object if already set.
4883     if (next_bitmap->isMarked(r->bottom())) {
4884       next_bitmap->clear(r->bottom());
4885     }
4886     _humongous_objects_reclaimed++;
4887     do {
4888       HeapRegion* next = g1h->next_region_in_humongous(r);
4889       _freed_bytes += r->used();
4890       r->set_containing_set(NULL);
4891       _humongous_regions_reclaimed++;
4892       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4893       r = next;
4894     } while (r != NULL);
4895 
4896     return false;
4897   }
4898 
4899   uint humongous_objects_reclaimed() {
4900     return _humongous_objects_reclaimed;
4901   }
4902 
4903   uint humongous_regions_reclaimed() {
4904     return _humongous_regions_reclaimed;
4905   }
4906 
4907   size_t bytes_freed() const {
4908     return _freed_bytes;
4909   }
4910 };
4911 
4912 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4913   assert_at_safepoint(true);
4914 
4915   if (!G1EagerReclaimHumongousObjects ||
4916       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4917     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4918     return;
4919   }
4920 
4921   double start_time = os::elapsedTime();
4922 
4923   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4924 
4925   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4926   heap_region_iterate(&cl);
4927 
4928   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4929 
4930   G1HRPrinter* hrp = hr_printer();
4931   if (hrp->is_active()) {
4932     FreeRegionListIterator iter(&local_cleanup_list);
4933     while (iter.more_available()) {
4934       HeapRegion* hr = iter.get_next();
4935       hrp->cleanup(hr);
4936     }
4937   }
4938 
4939   prepend_to_freelist(&local_cleanup_list);
4940   decrement_summary_bytes(cl.bytes_freed());
4941 
4942   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4943                                                                     cl.humongous_objects_reclaimed());
4944 }
4945 
4946 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4947 public:
4948   virtual bool doHeapRegion(HeapRegion* r) {
4949     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4950     G1CollectedHeap::heap()->clear_in_cset(r);
4951     r->set_young_index_in_cset(-1);
4952     return false;
4953   }
4954 };
4955 
4956 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4957   G1AbandonCollectionSetClosure cl;
4958   collection_set->iterate(&cl);
4959 
4960   collection_set->clear();
4961   collection_set->stop_incremental_building();
4962 }
4963 
4964 void G1CollectedHeap::set_free_regions_coming() {
4965   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4966 
4967   assert(!free_regions_coming(), "pre-condition");
4968   _free_regions_coming = true;
4969 }
4970 
4971 void G1CollectedHeap::reset_free_regions_coming() {
4972   assert(free_regions_coming(), "pre-condition");
4973 
4974   {
4975     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4976     _free_regions_coming = false;
4977     SecondaryFreeList_lock->notify_all();
4978   }
4979 
4980   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4981 }
4982 
4983 void G1CollectedHeap::wait_while_free_regions_coming() {
4984   // Most of the time we won't have to wait, so let's do a quick test
4985   // first before we take the lock.
4986   if (!free_regions_coming()) {
4987     return;
4988   }
4989 
4990   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4991 
4992   {
4993     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4994     while (free_regions_coming()) {
4995       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4996     }
4997   }
4998 
4999   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5000 }
5001 
5002 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5003   return _allocator->is_retained_old_region(hr);
5004 }
5005 
5006 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5007   _eden.add(hr);
5008   _g1_policy->set_region_eden(hr);
5009 }
5010 
5011 #ifdef ASSERT
5012 
5013 class NoYoungRegionsClosure: public HeapRegionClosure {
5014 private:
5015   bool _success;
5016 public:
5017   NoYoungRegionsClosure() : _success(true) { }
5018   bool doHeapRegion(HeapRegion* r) {
5019     if (r->is_young()) {
5020       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5021                             p2i(r->bottom()), p2i(r->end()));
5022       _success = false;
5023     }
5024     return false;
5025   }
5026   bool success() { return _success; }
5027 };
5028 
5029 bool G1CollectedHeap::check_young_list_empty() {
5030   bool ret = (young_regions_count() == 0);
5031 
5032   NoYoungRegionsClosure closure;
5033   heap_region_iterate(&closure);
5034   ret = ret && closure.success();
5035 
5036   return ret;
5037 }
5038 
5039 #endif // ASSERT
5040 
5041 class TearDownRegionSetsClosure : public HeapRegionClosure {
5042 private:
5043   HeapRegionSet *_old_set;
5044 
5045 public:
5046   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5047 
5048   bool doHeapRegion(HeapRegion* r) {
5049     if (r->is_old()) {
5050       _old_set->remove(r);
5051     } else if(r->is_young()) {
5052       r->uninstall_surv_rate_group();
5053     } else {
5054       // We ignore free regions, we'll empty the free list afterwards.
5055       // We ignore humongous regions, we're not tearing down the
5056       // humongous regions set.
5057       assert(r->is_free() || r->is_humongous(),
5058              "it cannot be another type");
5059     }
5060     return false;
5061   }
5062 
5063   ~TearDownRegionSetsClosure() {
5064     assert(_old_set->is_empty(), "post-condition");
5065   }
5066 };
5067 
5068 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5069   assert_at_safepoint(true /* should_be_vm_thread */);
5070 
5071   if (!free_list_only) {
5072     TearDownRegionSetsClosure cl(&_old_set);
5073     heap_region_iterate(&cl);
5074 
5075     // Note that emptying the _young_list is postponed and instead done as
5076     // the first step when rebuilding the regions sets again. The reason for
5077     // this is that during a full GC string deduplication needs to know if
5078     // a collected region was young or old when the full GC was initiated.
5079   }
5080   _hrm.remove_all_free_regions();
5081 }
5082 
5083 void G1CollectedHeap::increase_used(size_t bytes) {
5084   _summary_bytes_used += bytes;
5085 }
5086 
5087 void G1CollectedHeap::decrease_used(size_t bytes) {
5088   assert(_summary_bytes_used >= bytes,
5089          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5090          _summary_bytes_used, bytes);
5091   _summary_bytes_used -= bytes;
5092 }
5093 
5094 void G1CollectedHeap::set_used(size_t bytes) {
5095   _summary_bytes_used = bytes;
5096 }
5097 
5098 class RebuildRegionSetsClosure : public HeapRegionClosure {
5099 private:
5100   bool            _free_list_only;
5101   HeapRegionSet*   _old_set;
5102   HeapRegionManager*   _hrm;
5103   size_t          _total_used;
5104 
5105 public:
5106   RebuildRegionSetsClosure(bool free_list_only,
5107                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5108     _free_list_only(free_list_only),
5109     _old_set(old_set), _hrm(hrm), _total_used(0) {
5110     assert(_hrm->num_free_regions() == 0, "pre-condition");
5111     if (!free_list_only) {
5112       assert(_old_set->is_empty(), "pre-condition");
5113     }
5114   }
5115 
5116   bool doHeapRegion(HeapRegion* r) {
5117     if (r->is_empty()) {
5118       // Add free regions to the free list
5119       r->set_free();
5120       r->set_allocation_context(AllocationContext::system());
5121       _hrm->insert_into_free_list(r);
5122     } else if (!_free_list_only) {
5123 
5124       if (r->is_humongous()) {
5125         // We ignore humongous regions. We left the humongous set unchanged.
5126       } else {
5127         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5128         // We now consider all regions old, so register as such. Leave
5129         // archive regions set that way, however, while still adding
5130         // them to the old set.
5131         if (!r->is_archive()) {
5132           r->set_old();
5133         }
5134         _old_set->add(r);
5135       }
5136       _total_used += r->used();
5137     }
5138 
5139     return false;
5140   }
5141 
5142   size_t total_used() {
5143     return _total_used;
5144   }
5145 };
5146 
5147 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5148   assert_at_safepoint(true /* should_be_vm_thread */);
5149 
5150   if (!free_list_only) {
5151     _eden.clear();
5152     _survivor.clear();
5153   }
5154 
5155   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5156   heap_region_iterate(&cl);
5157 
5158   if (!free_list_only) {
5159     set_used(cl.total_used());
5160     if (_archive_allocator != NULL) {
5161       _archive_allocator->clear_used();
5162     }
5163   }
5164   assert(used_unlocked() == recalculate_used(),
5165          "inconsistent used_unlocked(), "
5166          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5167          used_unlocked(), recalculate_used());
5168 }
5169 
5170 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5171   _refine_cte_cl->set_concurrent(concurrent);
5172 }
5173 
5174 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5175   HeapRegion* hr = heap_region_containing(p);
5176   return hr->is_in(p);
5177 }
5178 
5179 // Methods for the mutator alloc region
5180 
5181 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5182                                                       bool force) {
5183   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5184   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5185   if (force || should_allocate) {
5186     HeapRegion* new_alloc_region = new_region(word_size,
5187                                               false /* is_old */,
5188                                               false /* do_expand */);
5189     if (new_alloc_region != NULL) {
5190       set_region_short_lived_locked(new_alloc_region);
5191       _hr_printer.alloc(new_alloc_region, !should_allocate);
5192       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5193       return new_alloc_region;
5194     }
5195   }
5196   return NULL;
5197 }
5198 
5199 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5200                                                   size_t allocated_bytes) {
5201   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5202   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5203 
5204   collection_set()->add_eden_region(alloc_region);
5205   increase_used(allocated_bytes);
5206   _hr_printer.retire(alloc_region);
5207   // We update the eden sizes here, when the region is retired,
5208   // instead of when it's allocated, since this is the point that its
5209   // used space has been recored in _summary_bytes_used.
5210   g1mm()->update_eden_size();
5211 }
5212 
5213 // Methods for the GC alloc regions
5214 
5215 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5216   if (dest.is_old()) {
5217     return true;
5218   } else {
5219     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5220   }
5221 }
5222 
5223 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5224   assert(FreeList_lock->owned_by_self(), "pre-condition");
5225 
5226   if (!has_more_regions(dest)) {
5227     return NULL;
5228   }
5229 
5230   const bool is_survivor = dest.is_young();
5231 
5232   HeapRegion* new_alloc_region = new_region(word_size,
5233                                             !is_survivor,
5234                                             true /* do_expand */);
5235   if (new_alloc_region != NULL) {
5236     // We really only need to do this for old regions given that we
5237     // should never scan survivors. But it doesn't hurt to do it
5238     // for survivors too.
5239     new_alloc_region->record_timestamp();
5240     if (is_survivor) {
5241       new_alloc_region->set_survivor();
5242       _survivor.add(new_alloc_region);
5243       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5244     } else {
5245       new_alloc_region->set_old();
5246       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5247     }
5248     _hr_printer.alloc(new_alloc_region);
5249     bool during_im = collector_state()->during_initial_mark_pause();
5250     new_alloc_region->note_start_of_copying(during_im);
5251     return new_alloc_region;
5252   }
5253   return NULL;
5254 }
5255 
5256 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5257                                              size_t allocated_bytes,
5258                                              InCSetState dest) {
5259   bool during_im = collector_state()->during_initial_mark_pause();
5260   alloc_region->note_end_of_copying(during_im);
5261   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5262   if (dest.is_old()) {
5263     _old_set.add(alloc_region);
5264   }
5265   _hr_printer.retire(alloc_region);
5266 }
5267 
5268 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5269   bool expanded = false;
5270   uint index = _hrm.find_highest_free(&expanded);
5271 
5272   if (index != G1_NO_HRM_INDEX) {
5273     if (expanded) {
5274       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5275                                 HeapRegion::GrainWords * HeapWordSize);
5276     }
5277     _hrm.allocate_free_regions_starting_at(index, 1);
5278     return region_at(index);
5279   }
5280   return NULL;
5281 }
5282 
5283 // Optimized nmethod scanning
5284 
5285 class RegisterNMethodOopClosure: public OopClosure {
5286   G1CollectedHeap* _g1h;
5287   nmethod* _nm;
5288 
5289   template <class T> void do_oop_work(T* p) {
5290     T heap_oop = oopDesc::load_heap_oop(p);
5291     if (!oopDesc::is_null(heap_oop)) {
5292       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5293       HeapRegion* hr = _g1h->heap_region_containing(obj);
5294       assert(!hr->is_continues_humongous(),
5295              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5296              " starting at " HR_FORMAT,
5297              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5298 
5299       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5300       hr->add_strong_code_root_locked(_nm);
5301     }
5302   }
5303 
5304 public:
5305   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5306     _g1h(g1h), _nm(nm) {}
5307 
5308   void do_oop(oop* p)       { do_oop_work(p); }
5309   void do_oop(narrowOop* p) { do_oop_work(p); }
5310 };
5311 
5312 class UnregisterNMethodOopClosure: public OopClosure {
5313   G1CollectedHeap* _g1h;
5314   nmethod* _nm;
5315 
5316   template <class T> void do_oop_work(T* p) {
5317     T heap_oop = oopDesc::load_heap_oop(p);
5318     if (!oopDesc::is_null(heap_oop)) {
5319       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5320       HeapRegion* hr = _g1h->heap_region_containing(obj);
5321       assert(!hr->is_continues_humongous(),
5322              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5323              " starting at " HR_FORMAT,
5324              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5325 
5326       hr->remove_strong_code_root(_nm);
5327     }
5328   }
5329 
5330 public:
5331   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5332     _g1h(g1h), _nm(nm) {}
5333 
5334   void do_oop(oop* p)       { do_oop_work(p); }
5335   void do_oop(narrowOop* p) { do_oop_work(p); }
5336 };
5337 
5338 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5339   CollectedHeap::register_nmethod(nm);
5340 
5341   guarantee(nm != NULL, "sanity");
5342   RegisterNMethodOopClosure reg_cl(this, nm);
5343   nm->oops_do(&reg_cl);
5344 }
5345 
5346 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5347   CollectedHeap::unregister_nmethod(nm);
5348 
5349   guarantee(nm != NULL, "sanity");
5350   UnregisterNMethodOopClosure reg_cl(this, nm);
5351   nm->oops_do(&reg_cl, true);
5352 }
5353 
5354 void G1CollectedHeap::purge_code_root_memory() {
5355   double purge_start = os::elapsedTime();
5356   G1CodeRootSet::purge();
5357   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5358   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5359 }
5360 
5361 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5362   G1CollectedHeap* _g1h;
5363 
5364 public:
5365   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5366     _g1h(g1h) {}
5367 
5368   void do_code_blob(CodeBlob* cb) {
5369     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5370     if (nm == NULL) {
5371       return;
5372     }
5373 
5374     if (ScavengeRootsInCode) {
5375       _g1h->register_nmethod(nm);
5376     }
5377   }
5378 };
5379 
5380 void G1CollectedHeap::rebuild_strong_code_roots() {
5381   RebuildStrongCodeRootClosure blob_cl(this);
5382   CodeCache::blobs_do(&blob_cl);
5383 }
--- EOF ---