rev 48000 : [mq]: open.patch

   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/concurrentMarkThread.inline.hpp"
  33 #include "gc/g1/g1Allocator.inline.hpp"
  34 #include "gc/g1/g1CollectedHeap.inline.hpp"
  35 #include "gc/g1/g1CollectionSet.hpp"
  36 #include "gc/g1/g1CollectorPolicy.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ConcurrentRefine.hpp"
  39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1FullCollector.hpp"
  42 #include "gc/g1/g1GCPhaseTimes.hpp"
  43 #include "gc/g1/g1HeapSizingPolicy.hpp"
  44 #include "gc/g1/g1HeapTransition.hpp"
  45 #include "gc/g1/g1HeapVerifier.hpp"
  46 #include "gc/g1/g1HotCardCache.hpp"

  47 #include "gc/g1/g1OopClosures.inline.hpp"
  48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  49 #include "gc/g1/g1Policy.hpp"
  50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  51 #include "gc/g1/g1RemSet.hpp"
  52 #include "gc/g1/g1RootClosures.hpp"
  53 #include "gc/g1/g1RootProcessor.hpp"
  54 #include "gc/g1/g1StringDedup.hpp"
  55 #include "gc/g1/g1YCTypes.hpp"
  56 #include "gc/g1/g1YoungRemSetSamplingThread.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/vm_operations_g1.hpp"
  61 #include "gc/shared/gcHeapSummary.hpp"
  62 #include "gc/shared/gcId.hpp"
  63 #include "gc/shared/gcLocker.inline.hpp"
  64 #include "gc/shared/gcTimer.hpp"
  65 #include "gc/shared/gcTrace.hpp"
  66 #include "gc/shared/gcTraceTime.inline.hpp"
  67 #include "gc/shared/generationSpec.hpp"
  68 #include "gc/shared/isGCActiveMark.hpp"
  69 #include "gc/shared/preservedMarks.inline.hpp"
  70 #include "gc/shared/suspendibleThreadSet.hpp"
  71 #include "gc/shared/referenceProcessor.inline.hpp"
  72 #include "gc/shared/taskqueue.inline.hpp"
  73 #include "gc/shared/weakProcessor.hpp"
  74 #include "logging/log.hpp"
  75 #include "memory/allocation.hpp"
  76 #include "memory/iterator.hpp"
  77 #include "memory/resourceArea.hpp"
  78 #include "oops/oop.inline.hpp"
  79 #include "prims/resolvedMethodTable.hpp"
  80 #include "runtime/atomic.hpp"
  81 #include "runtime/init.hpp"
  82 #include "runtime/orderAccess.inline.hpp"
  83 #include "runtime/threadSMR.hpp"
  84 #include "runtime/vmThread.hpp"
  85 #include "utilities/align.hpp"
  86 #include "utilities/globalDefinitions.hpp"
  87 #include "utilities/stack.inline.hpp"
  88 
  89 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  90 
  91 // INVARIANTS/NOTES
  92 //
  93 // All allocation activity covered by the G1CollectedHeap interface is
  94 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  95 // and allocate_new_tlab, which are the "entry" points to the
  96 // allocation code from the rest of the JVM.  (Note that this does not
  97 // apply to TLAB allocation, which is not part of this interface: it
  98 // is done by clients of this interface.)
  99 
 100 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 101  private:
 102   size_t _num_dirtied;
 103   G1CollectedHeap* _g1h;
 104   G1SATBCardTableLoggingModRefBS* _g1_bs;
 105 
 106   HeapRegion* region_for_card(jbyte* card_ptr) const {
 107     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 108   }
 109 
 110   bool will_become_free(HeapRegion* hr) const {
 111     // A region will be freed by free_collection_set if the region is in the
 112     // collection set and has not had an evacuation failure.
 113     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 114   }
 115 
 116  public:
 117   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 118     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 119 
 120   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 121     HeapRegion* hr = region_for_card(card_ptr);
 122 
 123     // Should only dirty cards in regions that won't be freed.
 124     if (!will_become_free(hr)) {
 125       *card_ptr = CardTableModRefBS::dirty_card_val();
 126       _num_dirtied++;
 127     }
 128 
 129     return true;
 130   }
 131 
 132   size_t num_dirtied()   const { return _num_dirtied; }
 133 };
 134 
 135 
 136 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 137   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 138 }
 139 
 140 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 141   // The from card cache is not the memory that is actually committed. So we cannot
 142   // take advantage of the zero_filled parameter.
 143   reset_from_card_cache(start_idx, num_regions);
 144 }
 145 
 146 
 147 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 148                                              MemRegion mr) {
 149   return new HeapRegion(hrs_index, bot(), mr);
 150 }
 151 
 152 // Private methods.
 153 
 154 HeapRegion*
 155 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 156   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 157   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 158     if (!_secondary_free_list.is_empty()) {
 159       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 160                                       "secondary_free_list has %u entries",
 161                                       _secondary_free_list.length());
 162       // It looks as if there are free regions available on the
 163       // secondary_free_list. Let's move them to the free_list and try
 164       // again to allocate from it.
 165       append_secondary_free_list();
 166 
 167       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 168              "empty we should have moved at least one entry to the free_list");
 169       HeapRegion* res = _hrm.allocate_free_region(is_old);
 170       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 171                                       "allocated " HR_FORMAT " from secondary_free_list",
 172                                       HR_FORMAT_PARAMS(res));
 173       return res;
 174     }
 175 
 176     // Wait here until we get notified either when (a) there are no
 177     // more free regions coming or (b) some regions have been moved on
 178     // the secondary_free_list.
 179     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 180   }
 181 
 182   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 183                                   "could not allocate from secondary_free_list");
 184   return NULL;
 185 }
 186 
 187 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 188   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 189          "the only time we use this to allocate a humongous region is "
 190          "when we are allocating a single humongous region");
 191 
 192   HeapRegion* res;
 193   if (G1StressConcRegionFreeing) {
 194     if (!_secondary_free_list.is_empty()) {
 195       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 196                                       "forced to look at the secondary_free_list");
 197       res = new_region_try_secondary_free_list(is_old);
 198       if (res != NULL) {
 199         return res;
 200       }
 201     }
 202   }
 203 
 204   res = _hrm.allocate_free_region(is_old);
 205 
 206   if (res == NULL) {
 207     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 208                                     "res == NULL, trying the secondary_free_list");
 209     res = new_region_try_secondary_free_list(is_old);
 210   }
 211   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 212     // Currently, only attempts to allocate GC alloc regions set
 213     // do_expand to true. So, we should only reach here during a
 214     // safepoint. If this assumption changes we might have to
 215     // reconsider the use of _expand_heap_after_alloc_failure.
 216     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 217 
 218     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 219                               word_size * HeapWordSize);
 220 
 221     if (expand(word_size * HeapWordSize)) {
 222       // Given that expand() succeeded in expanding the heap, and we
 223       // always expand the heap by an amount aligned to the heap
 224       // region size, the free list should in theory not be empty.
 225       // In either case allocate_free_region() will check for NULL.
 226       res = _hrm.allocate_free_region(is_old);
 227     } else {
 228       _expand_heap_after_alloc_failure = false;
 229     }
 230   }
 231   return res;
 232 }
 233 
 234 HeapWord*
 235 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 236                                                            uint num_regions,
 237                                                            size_t word_size,
 238                                                            AllocationContext_t context) {
 239   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 240   assert(is_humongous(word_size), "word_size should be humongous");
 241   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 242 
 243   // Index of last region in the series.
 244   uint last = first + num_regions - 1;
 245 
 246   // We need to initialize the region(s) we just discovered. This is
 247   // a bit tricky given that it can happen concurrently with
 248   // refinement threads refining cards on these regions and
 249   // potentially wanting to refine the BOT as they are scanning
 250   // those cards (this can happen shortly after a cleanup; see CR
 251   // 6991377). So we have to set up the region(s) carefully and in
 252   // a specific order.
 253 
 254   // The word size sum of all the regions we will allocate.
 255   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 256   assert(word_size <= word_size_sum, "sanity");
 257 
 258   // This will be the "starts humongous" region.
 259   HeapRegion* first_hr = region_at(first);
 260   // The header of the new object will be placed at the bottom of
 261   // the first region.
 262   HeapWord* new_obj = first_hr->bottom();
 263   // This will be the new top of the new object.
 264   HeapWord* obj_top = new_obj + word_size;
 265 
 266   // First, we need to zero the header of the space that we will be
 267   // allocating. When we update top further down, some refinement
 268   // threads might try to scan the region. By zeroing the header we
 269   // ensure that any thread that will try to scan the region will
 270   // come across the zero klass word and bail out.
 271   //
 272   // NOTE: It would not have been correct to have used
 273   // CollectedHeap::fill_with_object() and make the space look like
 274   // an int array. The thread that is doing the allocation will
 275   // later update the object header to a potentially different array
 276   // type and, for a very short period of time, the klass and length
 277   // fields will be inconsistent. This could cause a refinement
 278   // thread to calculate the object size incorrectly.
 279   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 280 
 281   // Next, pad out the unused tail of the last region with filler
 282   // objects, for improved usage accounting.
 283   // How many words we use for filler objects.
 284   size_t word_fill_size = word_size_sum - word_size;
 285 
 286   // How many words memory we "waste" which cannot hold a filler object.
 287   size_t words_not_fillable = 0;
 288 
 289   if (word_fill_size >= min_fill_size()) {
 290     fill_with_objects(obj_top, word_fill_size);
 291   } else if (word_fill_size > 0) {
 292     // We have space to fill, but we cannot fit an object there.
 293     words_not_fillable = word_fill_size;
 294     word_fill_size = 0;
 295   }
 296 
 297   // We will set up the first region as "starts humongous". This
 298   // will also update the BOT covering all the regions to reflect
 299   // that there is a single object that starts at the bottom of the
 300   // first region.
 301   first_hr->set_starts_humongous(obj_top, word_fill_size);
 302   first_hr->set_allocation_context(context);
 303   // Then, if there are any, we will set up the "continues
 304   // humongous" regions.
 305   HeapRegion* hr = NULL;
 306   for (uint i = first + 1; i <= last; ++i) {
 307     hr = region_at(i);
 308     hr->set_continues_humongous(first_hr);
 309     hr->set_allocation_context(context);
 310   }
 311 
 312   // Up to this point no concurrent thread would have been able to
 313   // do any scanning on any region in this series. All the top
 314   // fields still point to bottom, so the intersection between
 315   // [bottom,top] and [card_start,card_end] will be empty. Before we
 316   // update the top fields, we'll do a storestore to make sure that
 317   // no thread sees the update to top before the zeroing of the
 318   // object header and the BOT initialization.
 319   OrderAccess::storestore();
 320 
 321   // Now, we will update the top fields of the "continues humongous"
 322   // regions except the last one.
 323   for (uint i = first; i < last; ++i) {
 324     hr = region_at(i);
 325     hr->set_top(hr->end());
 326   }
 327 
 328   hr = region_at(last);
 329   // If we cannot fit a filler object, we must set top to the end
 330   // of the humongous object, otherwise we cannot iterate the heap
 331   // and the BOT will not be complete.
 332   hr->set_top(hr->end() - words_not_fillable);
 333 
 334   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 335          "obj_top should be in last region");
 336 
 337   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 338 
 339   assert(words_not_fillable == 0 ||
 340          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 341          "Miscalculation in humongous allocation");
 342 
 343   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 344 
 345   for (uint i = first; i <= last; ++i) {
 346     hr = region_at(i);
 347     _humongous_set.add(hr);
 348     _hr_printer.alloc(hr);
 349   }
 350 
 351   return new_obj;
 352 }
 353 
 354 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 355   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 356   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 357 }
 358 
 359 // If could fit into free regions w/o expansion, try.
 360 // Otherwise, if can expand, do so.
 361 // Otherwise, if using ex regions might help, try with ex given back.
 362 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 363   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 364 
 365   _verifier->verify_region_sets_optional();
 366 
 367   uint first = G1_NO_HRM_INDEX;
 368   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 369 
 370   if (obj_regions == 1) {
 371     // Only one region to allocate, try to use a fast path by directly allocating
 372     // from the free lists. Do not try to expand here, we will potentially do that
 373     // later.
 374     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 375     if (hr != NULL) {
 376       first = hr->hrm_index();
 377     }
 378   } else {
 379     // We can't allocate humongous regions spanning more than one region while
 380     // cleanupComplete() is running, since some of the regions we find to be
 381     // empty might not yet be added to the free list. It is not straightforward
 382     // to know in which list they are on so that we can remove them. We only
 383     // need to do this if we need to allocate more than one region to satisfy the
 384     // current humongous allocation request. If we are only allocating one region
 385     // we use the one-region region allocation code (see above), that already
 386     // potentially waits for regions from the secondary free list.
 387     wait_while_free_regions_coming();
 388     append_secondary_free_list_if_not_empty_with_lock();
 389 
 390     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 391     // are lucky enough to find some.
 392     first = _hrm.find_contiguous_only_empty(obj_regions);
 393     if (first != G1_NO_HRM_INDEX) {
 394       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 395     }
 396   }
 397 
 398   if (first == G1_NO_HRM_INDEX) {
 399     // Policy: We could not find enough regions for the humongous object in the
 400     // free list. Look through the heap to find a mix of free and uncommitted regions.
 401     // If so, try expansion.
 402     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 403     if (first != G1_NO_HRM_INDEX) {
 404       // We found something. Make sure these regions are committed, i.e. expand
 405       // the heap. Alternatively we could do a defragmentation GC.
 406       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 407                                     word_size * HeapWordSize);
 408 
 409       _hrm.expand_at(first, obj_regions, workers());
 410       g1_policy()->record_new_heap_size(num_regions());
 411 
 412 #ifdef ASSERT
 413       for (uint i = first; i < first + obj_regions; ++i) {
 414         HeapRegion* hr = region_at(i);
 415         assert(hr->is_free(), "sanity");
 416         assert(hr->is_empty(), "sanity");
 417         assert(is_on_master_free_list(hr), "sanity");
 418       }
 419 #endif
 420       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 421     } else {
 422       // Policy: Potentially trigger a defragmentation GC.
 423     }
 424   }
 425 
 426   HeapWord* result = NULL;
 427   if (first != G1_NO_HRM_INDEX) {
 428     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 429                                                        word_size, context);
 430     assert(result != NULL, "it should always return a valid result");
 431 
 432     // A successful humongous object allocation changes the used space
 433     // information of the old generation so we need to recalculate the
 434     // sizes and update the jstat counters here.
 435     g1mm()->update_sizes();
 436   }
 437 
 438   _verifier->verify_region_sets_optional();
 439 
 440   return result;
 441 }
 442 
 443 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 444   assert_heap_not_locked_and_not_at_safepoint();
 445   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 446 
 447   uint dummy_gc_count_before;
 448   uint dummy_gclocker_retry_count = 0;
 449   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 450 }
 451 
 452 HeapWord*
 453 G1CollectedHeap::mem_allocate(size_t word_size,
 454                               bool*  gc_overhead_limit_was_exceeded) {
 455   assert_heap_not_locked_and_not_at_safepoint();
 456 
 457   // Loop until the allocation is satisfied, or unsatisfied after GC.
 458   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 459     uint gc_count_before;
 460 
 461     HeapWord* result = NULL;
 462     if (!is_humongous(word_size)) {
 463       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 464     } else {
 465       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 466     }
 467     if (result != NULL) {
 468       return result;
 469     }
 470 
 471     // Create the garbage collection operation...
 472     VM_G1CollectForAllocation op(gc_count_before, word_size);
 473     op.set_allocation_context(AllocationContext::current());
 474 
 475     // ...and get the VM thread to execute it.
 476     VMThread::execute(&op);
 477 
 478     if (op.prologue_succeeded() && op.pause_succeeded()) {
 479       // If the operation was successful we'll return the result even
 480       // if it is NULL. If the allocation attempt failed immediately
 481       // after a Full GC, it's unlikely we'll be able to allocate now.
 482       HeapWord* result = op.result();
 483       if (result != NULL && !is_humongous(word_size)) {
 484         // Allocations that take place on VM operations do not do any
 485         // card dirtying and we have to do it here. We only have to do
 486         // this for non-humongous allocations, though.
 487         dirty_young_block(result, word_size);
 488       }
 489       return result;
 490     } else {
 491       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 492         return NULL;
 493       }
 494       assert(op.result() == NULL,
 495              "the result should be NULL if the VM op did not succeed");
 496     }
 497 
 498     // Give a warning if we seem to be looping forever.
 499     if ((QueuedAllocationWarningCount > 0) &&
 500         (try_count % QueuedAllocationWarningCount == 0)) {
 501       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 502     }
 503   }
 504 
 505   ShouldNotReachHere();
 506   return NULL;
 507 }
 508 
 509 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 510                                                    AllocationContext_t context,
 511                                                    uint* gc_count_before_ret,
 512                                                    uint* gclocker_retry_count_ret) {
 513   // Make sure you read the note in attempt_allocation_humongous().
 514 
 515   assert_heap_not_locked_and_not_at_safepoint();
 516   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 517          "be called for humongous allocation requests");
 518 
 519   // We should only get here after the first-level allocation attempt
 520   // (attempt_allocation()) failed to allocate.
 521 
 522   // We will loop until a) we manage to successfully perform the
 523   // allocation or b) we successfully schedule a collection which
 524   // fails to perform the allocation. b) is the only case when we'll
 525   // return NULL.
 526   HeapWord* result = NULL;
 527   for (int try_count = 1; /* we'll return */; try_count += 1) {
 528     bool should_try_gc;
 529     uint gc_count_before;
 530 
 531     {
 532       MutexLockerEx x(Heap_lock);
 533       result = _allocator->attempt_allocation_locked(word_size, context);
 534       if (result != NULL) {
 535         return result;
 536       }
 537 
 538       if (GCLocker::is_active_and_needs_gc()) {
 539         if (g1_policy()->can_expand_young_list()) {
 540           // No need for an ergo verbose message here,
 541           // can_expand_young_list() does this when it returns true.
 542           result = _allocator->attempt_allocation_force(word_size, context);
 543           if (result != NULL) {
 544             return result;
 545           }
 546         }
 547         should_try_gc = false;
 548       } else {
 549         // The GCLocker may not be active but the GCLocker initiated
 550         // GC may not yet have been performed (GCLocker::needs_gc()
 551         // returns true). In this case we do not try this GC and
 552         // wait until the GCLocker initiated GC is performed, and
 553         // then retry the allocation.
 554         if (GCLocker::needs_gc()) {
 555           should_try_gc = false;
 556         } else {
 557           // Read the GC count while still holding the Heap_lock.
 558           gc_count_before = total_collections();
 559           should_try_gc = true;
 560         }
 561       }
 562     }
 563 
 564     if (should_try_gc) {
 565       bool succeeded;
 566       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 567                                    GCCause::_g1_inc_collection_pause);
 568       if (result != NULL) {
 569         assert(succeeded, "only way to get back a non-NULL result");
 570         return result;
 571       }
 572 
 573       if (succeeded) {
 574         // If we get here we successfully scheduled a collection which
 575         // failed to allocate. No point in trying to allocate
 576         // further. We'll just return NULL.
 577         MutexLockerEx x(Heap_lock);
 578         *gc_count_before_ret = total_collections();
 579         return NULL;
 580       }
 581     } else {
 582       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 583         MutexLockerEx x(Heap_lock);
 584         *gc_count_before_ret = total_collections();
 585         return NULL;
 586       }
 587       // The GCLocker is either active or the GCLocker initiated
 588       // GC has not yet been performed. Stall until it is and
 589       // then retry the allocation.
 590       GCLocker::stall_until_clear();
 591       (*gclocker_retry_count_ret) += 1;
 592     }
 593 
 594     // We can reach here if we were unsuccessful in scheduling a
 595     // collection (because another thread beat us to it) or if we were
 596     // stalled due to the GC locker. In either can we should retry the
 597     // allocation attempt in case another thread successfully
 598     // performed a collection and reclaimed enough space. We do the
 599     // first attempt (without holding the Heap_lock) here and the
 600     // follow-on attempt will be at the start of the next loop
 601     // iteration (after taking the Heap_lock).
 602     result = _allocator->attempt_allocation(word_size, context);
 603     if (result != NULL) {
 604       return result;
 605     }
 606 
 607     // Give a warning if we seem to be looping forever.
 608     if ((QueuedAllocationWarningCount > 0) &&
 609         (try_count % QueuedAllocationWarningCount == 0)) {
 610       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 611                       "retries %d times", try_count);
 612     }
 613   }
 614 
 615   ShouldNotReachHere();
 616   return NULL;
 617 }
 618 
 619 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 620   assert_at_safepoint(true /* should_be_vm_thread */);
 621   if (_archive_allocator == NULL) {
 622     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 623   }
 624 }
 625 
 626 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 627   // Allocations in archive regions cannot be of a size that would be considered
 628   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 629   // may be different at archive-restore time.
 630   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 631 }
 632 
 633 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 634   assert_at_safepoint(true /* should_be_vm_thread */);
 635   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 636   if (is_archive_alloc_too_large(word_size)) {
 637     return NULL;
 638   }
 639   return _archive_allocator->archive_mem_allocate(word_size);
 640 }
 641 
 642 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 643                                               size_t end_alignment_in_bytes) {
 644   assert_at_safepoint(true /* should_be_vm_thread */);
 645   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 646 
 647   // Call complete_archive to do the real work, filling in the MemRegion
 648   // array with the archive regions.
 649   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 650   delete _archive_allocator;
 651   _archive_allocator = NULL;
 652 }
 653 
 654 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 655   assert(ranges != NULL, "MemRegion array NULL");
 656   assert(count != 0, "No MemRegions provided");
 657   MemRegion reserved = _hrm.reserved();
 658   for (size_t i = 0; i < count; i++) {
 659     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 660       return false;
 661     }
 662   }
 663   return true;
 664 }
 665 
 666 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 667                                             size_t count,
 668                                             bool open) {
 669   assert(!is_init_completed(), "Expect to be called at JVM init time");
 670   assert(ranges != NULL, "MemRegion array NULL");
 671   assert(count != 0, "No MemRegions provided");
 672   MutexLockerEx x(Heap_lock);
 673 
 674   MemRegion reserved = _hrm.reserved();
 675   HeapWord* prev_last_addr = NULL;
 676   HeapRegion* prev_last_region = NULL;
 677 
 678   // Temporarily disable pretouching of heap pages. This interface is used
 679   // when mmap'ing archived heap data in, so pre-touching is wasted.
 680   FlagSetting fs(AlwaysPreTouch, false);
 681 
 682   // Enable archive object checking used by G1MarkSweep. We have to let it know
 683   // about each archive range, so that objects in those ranges aren't marked.
 684   G1ArchiveAllocator::enable_archive_object_check();
 685 
 686   // For each specified MemRegion range, allocate the corresponding G1
 687   // regions and mark them as archive regions. We expect the ranges
 688   // in ascending starting address order, without overlap.
 689   for (size_t i = 0; i < count; i++) {
 690     MemRegion curr_range = ranges[i];
 691     HeapWord* start_address = curr_range.start();
 692     size_t word_size = curr_range.word_size();
 693     HeapWord* last_address = curr_range.last();
 694     size_t commits = 0;
 695 
 696     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 697               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 698               p2i(start_address), p2i(last_address));
 699     guarantee(start_address > prev_last_addr,
 700               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 701               p2i(start_address), p2i(prev_last_addr));
 702     prev_last_addr = last_address;
 703 
 704     // Check for ranges that start in the same G1 region in which the previous
 705     // range ended, and adjust the start address so we don't try to allocate
 706     // the same region again. If the current range is entirely within that
 707     // region, skip it, just adjusting the recorded top.
 708     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 709     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 710       start_address = start_region->end();
 711       if (start_address > last_address) {
 712         increase_used(word_size * HeapWordSize);
 713         start_region->set_top(last_address + 1);
 714         continue;
 715       }
 716       start_region->set_top(start_address);
 717       curr_range = MemRegion(start_address, last_address + 1);
 718       start_region = _hrm.addr_to_region(start_address);
 719     }
 720 
 721     // Perform the actual region allocation, exiting if it fails.
 722     // Then note how much new space we have allocated.
 723     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 724       return false;
 725     }
 726     increase_used(word_size * HeapWordSize);
 727     if (commits != 0) {
 728       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 729                                 HeapRegion::GrainWords * HeapWordSize * commits);
 730 
 731     }
 732 
 733     // Mark each G1 region touched by the range as archive, add it to
 734     // the old set, and set the allocation context and top.
 735     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 736     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 737     prev_last_region = last_region;
 738 
 739     while (curr_region != NULL) {
 740       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 741              "Region already in use (index %u)", curr_region->hrm_index());
 742       curr_region->set_allocation_context(AllocationContext::system());
 743       if (open) {
 744         curr_region->set_open_archive();
 745       } else {
 746         curr_region->set_closed_archive();
 747       }
 748       _hr_printer.alloc(curr_region);
 749       _old_set.add(curr_region);
 750       HeapWord* top;
 751       HeapRegion* next_region;
 752       if (curr_region != last_region) {
 753         top = curr_region->end();
 754         next_region = _hrm.next_region_in_heap(curr_region);
 755       } else {
 756         top = last_address + 1;
 757         next_region = NULL;
 758       }
 759       curr_region->set_top(top);
 760       curr_region->set_first_dead(top);
 761       curr_region->set_end_of_live(top);
 762       curr_region = next_region;
 763     }
 764 
 765     // Notify mark-sweep of the archive
 766     G1ArchiveAllocator::set_range_archive(curr_range, open);
 767   }
 768   return true;
 769 }
 770 
 771 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 772   assert(!is_init_completed(), "Expect to be called at JVM init time");
 773   assert(ranges != NULL, "MemRegion array NULL");
 774   assert(count != 0, "No MemRegions provided");
 775   MemRegion reserved = _hrm.reserved();
 776   HeapWord *prev_last_addr = NULL;
 777   HeapRegion* prev_last_region = NULL;
 778 
 779   // For each MemRegion, create filler objects, if needed, in the G1 regions
 780   // that contain the address range. The address range actually within the
 781   // MemRegion will not be modified. That is assumed to have been initialized
 782   // elsewhere, probably via an mmap of archived heap data.
 783   MutexLockerEx x(Heap_lock);
 784   for (size_t i = 0; i < count; i++) {
 785     HeapWord* start_address = ranges[i].start();
 786     HeapWord* last_address = ranges[i].last();
 787 
 788     assert(reserved.contains(start_address) && reserved.contains(last_address),
 789            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 790            p2i(start_address), p2i(last_address));
 791     assert(start_address > prev_last_addr,
 792            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 793            p2i(start_address), p2i(prev_last_addr));
 794 
 795     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 796     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 797     HeapWord* bottom_address = start_region->bottom();
 798 
 799     // Check for a range beginning in the same region in which the
 800     // previous one ended.
 801     if (start_region == prev_last_region) {
 802       bottom_address = prev_last_addr + 1;
 803     }
 804 
 805     // Verify that the regions were all marked as archive regions by
 806     // alloc_archive_regions.
 807     HeapRegion* curr_region = start_region;
 808     while (curr_region != NULL) {
 809       guarantee(curr_region->is_archive(),
 810                 "Expected archive region at index %u", curr_region->hrm_index());
 811       if (curr_region != last_region) {
 812         curr_region = _hrm.next_region_in_heap(curr_region);
 813       } else {
 814         curr_region = NULL;
 815       }
 816     }
 817 
 818     prev_last_addr = last_address;
 819     prev_last_region = last_region;
 820 
 821     // Fill the memory below the allocated range with dummy object(s),
 822     // if the region bottom does not match the range start, or if the previous
 823     // range ended within the same G1 region, and there is a gap.
 824     if (start_address != bottom_address) {
 825       size_t fill_size = pointer_delta(start_address, bottom_address);
 826       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 827       increase_used(fill_size * HeapWordSize);
 828     }
 829   }
 830 }
 831 
 832 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 833                                                      uint* gc_count_before_ret,
 834                                                      uint* gclocker_retry_count_ret) {
 835   assert_heap_not_locked_and_not_at_safepoint();
 836   assert(!is_humongous(word_size), "attempt_allocation() should not "
 837          "be called for humongous allocation requests");
 838 
 839   AllocationContext_t context = AllocationContext::current();
 840   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 841 
 842   if (result == NULL) {
 843     result = attempt_allocation_slow(word_size,
 844                                      context,
 845                                      gc_count_before_ret,
 846                                      gclocker_retry_count_ret);
 847   }
 848   assert_heap_not_locked();
 849   if (result != NULL) {
 850     dirty_young_block(result, word_size);
 851   }
 852   return result;
 853 }
 854 
 855 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 856   assert(!is_init_completed(), "Expect to be called at JVM init time");
 857   assert(ranges != NULL, "MemRegion array NULL");
 858   assert(count != 0, "No MemRegions provided");
 859   MemRegion reserved = _hrm.reserved();
 860   HeapWord* prev_last_addr = NULL;
 861   HeapRegion* prev_last_region = NULL;
 862   size_t size_used = 0;
 863   size_t uncommitted_regions = 0;
 864 
 865   // For each Memregion, free the G1 regions that constitute it, and
 866   // notify mark-sweep that the range is no longer to be considered 'archive.'
 867   MutexLockerEx x(Heap_lock);
 868   for (size_t i = 0; i < count; i++) {
 869     HeapWord* start_address = ranges[i].start();
 870     HeapWord* last_address = ranges[i].last();
 871 
 872     assert(reserved.contains(start_address) && reserved.contains(last_address),
 873            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 874            p2i(start_address), p2i(last_address));
 875     assert(start_address > prev_last_addr,
 876            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 877            p2i(start_address), p2i(prev_last_addr));
 878     size_used += ranges[i].byte_size();
 879     prev_last_addr = last_address;
 880 
 881     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 882     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 883 
 884     // Check for ranges that start in the same G1 region in which the previous
 885     // range ended, and adjust the start address so we don't try to free
 886     // the same region again. If the current range is entirely within that
 887     // region, skip it.
 888     if (start_region == prev_last_region) {
 889       start_address = start_region->end();
 890       if (start_address > last_address) {
 891         continue;
 892       }
 893       start_region = _hrm.addr_to_region(start_address);
 894     }
 895     prev_last_region = last_region;
 896 
 897     // After verifying that each region was marked as an archive region by
 898     // alloc_archive_regions, set it free and empty and uncommit it.
 899     HeapRegion* curr_region = start_region;
 900     while (curr_region != NULL) {
 901       guarantee(curr_region->is_archive(),
 902                 "Expected archive region at index %u", curr_region->hrm_index());
 903       uint curr_index = curr_region->hrm_index();
 904       _old_set.remove(curr_region);
 905       curr_region->set_free();
 906       curr_region->set_top(curr_region->bottom());
 907       if (curr_region != last_region) {
 908         curr_region = _hrm.next_region_in_heap(curr_region);
 909       } else {
 910         curr_region = NULL;
 911       }
 912       _hrm.shrink_at(curr_index, 1);
 913       uncommitted_regions++;
 914     }
 915 
 916     // Notify mark-sweep that this is no longer an archive range.
 917     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 918   }
 919 
 920   if (uncommitted_regions != 0) {
 921     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 922                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 923   }
 924   decrease_used(size_used);
 925 }
 926 
 927 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 928                                                         uint* gc_count_before_ret,
 929                                                         uint* gclocker_retry_count_ret) {
 930   // The structure of this method has a lot of similarities to
 931   // attempt_allocation_slow(). The reason these two were not merged
 932   // into a single one is that such a method would require several "if
 933   // allocation is not humongous do this, otherwise do that"
 934   // conditional paths which would obscure its flow. In fact, an early
 935   // version of this code did use a unified method which was harder to
 936   // follow and, as a result, it had subtle bugs that were hard to
 937   // track down. So keeping these two methods separate allows each to
 938   // be more readable. It will be good to keep these two in sync as
 939   // much as possible.
 940 
 941   assert_heap_not_locked_and_not_at_safepoint();
 942   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 943          "should only be called for humongous allocations");
 944 
 945   // Humongous objects can exhaust the heap quickly, so we should check if we
 946   // need to start a marking cycle at each humongous object allocation. We do
 947   // the check before we do the actual allocation. The reason for doing it
 948   // before the allocation is that we avoid having to keep track of the newly
 949   // allocated memory while we do a GC.
 950   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 951                                            word_size)) {
 952     collect(GCCause::_g1_humongous_allocation);
 953   }
 954 
 955   // We will loop until a) we manage to successfully perform the
 956   // allocation or b) we successfully schedule a collection which
 957   // fails to perform the allocation. b) is the only case when we'll
 958   // return NULL.
 959   HeapWord* result = NULL;
 960   for (int try_count = 1; /* we'll return */; try_count += 1) {
 961     bool should_try_gc;
 962     uint gc_count_before;
 963 
 964     {
 965       MutexLockerEx x(Heap_lock);
 966 
 967       // Given that humongous objects are not allocated in young
 968       // regions, we'll first try to do the allocation without doing a
 969       // collection hoping that there's enough space in the heap.
 970       result = humongous_obj_allocate(word_size, AllocationContext::current());
 971       if (result != NULL) {
 972         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 973         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 974         return result;
 975       }
 976 
 977       if (GCLocker::is_active_and_needs_gc()) {
 978         should_try_gc = false;
 979       } else {
 980          // The GCLocker may not be active but the GCLocker initiated
 981         // GC may not yet have been performed (GCLocker::needs_gc()
 982         // returns true). In this case we do not try this GC and
 983         // wait until the GCLocker initiated GC is performed, and
 984         // then retry the allocation.
 985         if (GCLocker::needs_gc()) {
 986           should_try_gc = false;
 987         } else {
 988           // Read the GC count while still holding the Heap_lock.
 989           gc_count_before = total_collections();
 990           should_try_gc = true;
 991         }
 992       }
 993     }
 994 
 995     if (should_try_gc) {
 996       // If we failed to allocate the humongous object, we should try to
 997       // do a collection pause (if we're allowed) in case it reclaims
 998       // enough space for the allocation to succeed after the pause.
 999 
1000       bool succeeded;
1001       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1002                                    GCCause::_g1_humongous_allocation);
1003       if (result != NULL) {
1004         assert(succeeded, "only way to get back a non-NULL result");
1005         return result;
1006       }
1007 
1008       if (succeeded) {
1009         // If we get here we successfully scheduled a collection which
1010         // failed to allocate. No point in trying to allocate
1011         // further. We'll just return NULL.
1012         MutexLockerEx x(Heap_lock);
1013         *gc_count_before_ret = total_collections();
1014         return NULL;
1015       }
1016     } else {
1017       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1018         MutexLockerEx x(Heap_lock);
1019         *gc_count_before_ret = total_collections();
1020         return NULL;
1021       }
1022       // The GCLocker is either active or the GCLocker initiated
1023       // GC has not yet been performed. Stall until it is and
1024       // then retry the allocation.
1025       GCLocker::stall_until_clear();
1026       (*gclocker_retry_count_ret) += 1;
1027     }
1028 
1029     // We can reach here if we were unsuccessful in scheduling a
1030     // collection (because another thread beat us to it) or if we were
1031     // stalled due to the GC locker. In either can we should retry the
1032     // allocation attempt in case another thread successfully
1033     // performed a collection and reclaimed enough space.  Give a
1034     // warning if we seem to be looping forever.
1035 
1036     if ((QueuedAllocationWarningCount > 0) &&
1037         (try_count % QueuedAllocationWarningCount == 0)) {
1038       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1039                       "retries %d times", try_count);
1040     }
1041   }
1042 
1043   ShouldNotReachHere();
1044   return NULL;
1045 }
1046 
1047 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1048                                                            AllocationContext_t context,
1049                                                            bool expect_null_mutator_alloc_region) {
1050   assert_at_safepoint(true /* should_be_vm_thread */);
1051   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1052          "the current alloc region was unexpectedly found to be non-NULL");
1053 
1054   if (!is_humongous(word_size)) {
1055     return _allocator->attempt_allocation_locked(word_size, context);
1056   } else {
1057     HeapWord* result = humongous_obj_allocate(word_size, context);
1058     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1059       collector_state()->set_initiate_conc_mark_if_possible(true);
1060     }
1061     return result;
1062   }
1063 
1064   ShouldNotReachHere();
1065 }
1066 
1067 class PostCompactionPrinterClosure: public HeapRegionClosure {
1068 private:
1069   G1HRPrinter* _hr_printer;
1070 public:
1071   bool doHeapRegion(HeapRegion* hr) {
1072     assert(!hr->is_young(), "not expecting to find young regions");
1073     _hr_printer->post_compaction(hr);
1074     return false;
1075   }
1076 
1077   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1078     : _hr_printer(hr_printer) { }
1079 };
1080 
1081 void G1CollectedHeap::print_hrm_post_compaction() {
1082   if (_hr_printer.is_active()) {
1083     PostCompactionPrinterClosure cl(hr_printer());
1084     heap_region_iterate(&cl);
1085   }
1086 
1087 }
1088 
1089 void G1CollectedHeap::abort_concurrent_cycle() {
1090   // Note: When we have a more flexible GC logging framework that
1091   // allows us to add optional attributes to a GC log record we
1092   // could consider timing and reporting how long we wait in the
1093   // following two methods.
1094   wait_while_free_regions_coming();
1095   // If we start the compaction before the CM threads finish
1096   // scanning the root regions we might trip them over as we'll
1097   // be moving objects / updating references. So let's wait until
1098   // they are done. By telling them to abort, they should complete
1099   // early.
1100   _cm->root_regions()->abort();
1101   _cm->root_regions()->wait_until_scan_finished();
1102   append_secondary_free_list_if_not_empty_with_lock();
1103 
1104   // Disable discovery and empty the discovered lists
1105   // for the CM ref processor.
1106   ref_processor_cm()->disable_discovery();
1107   ref_processor_cm()->abandon_partial_discovery();
1108   ref_processor_cm()->verify_no_references_recorded();
1109 
1110   // Abandon current iterations of concurrent marking and concurrent
1111   // refinement, if any are in progress.
1112   concurrent_mark()->abort();
1113 }
1114 
1115 void G1CollectedHeap::prepare_heap_for_full_collection() {
1116   // Make sure we'll choose a new allocation region afterwards.
1117   _allocator->release_mutator_alloc_region();
1118   _allocator->abandon_gc_alloc_regions();
1119   g1_rem_set()->cleanupHRRS();
1120 
1121   // We may have added regions to the current incremental collection
1122   // set between the last GC or pause and now. We need to clear the
1123   // incremental collection set and then start rebuilding it afresh
1124   // after this full GC.
1125   abandon_collection_set(collection_set());
1126 
1127   tear_down_region_sets(false /* free_list_only */);
1128   collector_state()->set_gcs_are_young(true);
1129 }
1130 
1131 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1132   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1133   assert(used() == recalculate_used(), "Should be equal");
1134   _verifier->verify_region_sets_optional();
1135   _verifier->verify_before_gc();
1136   _verifier->check_bitmaps("Full GC Start");
1137 }
1138 
1139 void G1CollectedHeap::prepare_heap_for_mutators() {
1140   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1141   ClassLoaderDataGraph::purge();
1142   MetaspaceAux::verify_metrics();
1143 
1144   // Prepare heap for normal collections.
1145   assert(num_free_regions() == 0, "we should not have added any free regions");
1146   rebuild_region_sets(false /* free_list_only */);
1147   abort_refinement();
1148   resize_if_necessary_after_full_collection();
1149 
1150   // Rebuild the strong code root lists for each region
1151   rebuild_strong_code_roots();
1152 
1153   // Start a new incremental collection set for the next pause
1154   start_new_collection_set();
1155 
1156   _allocator->init_mutator_alloc_region();
1157 
1158   // Post collection state updates.
1159   MetaspaceGC::compute_new_size();
1160 }
1161 
1162 void G1CollectedHeap::abort_refinement() {
1163   if (_hot_card_cache->use_cache()) {
1164     _hot_card_cache->reset_hot_cache();
1165   }
1166 
1167   // Discard all remembered set updates.
1168   JavaThread::dirty_card_queue_set().abandon_logs();
1169   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1170 }
1171 
1172 void G1CollectedHeap::verify_after_full_collection() {
1173   check_gc_time_stamps();
1174   _hrm.verify_optional();
1175   _verifier->verify_region_sets_optional();
1176   _verifier->verify_after_gc();
1177   // Clear the previous marking bitmap, if needed for bitmap verification.
1178   // Note we cannot do this when we clear the next marking bitmap in
1179   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1180   // objects marked during a full GC against the previous bitmap.
1181   // But we need to clear it before calling check_bitmaps below since
1182   // the full GC has compacted objects and updated TAMS but not updated
1183   // the prev bitmap.
1184   if (G1VerifyBitmaps) {
1185     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1186     _cm->clear_prev_bitmap(workers());
1187   }
1188   _verifier->check_bitmaps("Full GC End");
1189 
1190   // At this point there should be no regions in the
1191   // entire heap tagged as young.
1192   assert(check_young_list_empty(), "young list should be empty at this point");
1193 
1194   // Note: since we've just done a full GC, concurrent
1195   // marking is no longer active. Therefore we need not
1196   // re-enable reference discovery for the CM ref processor.
1197   // That will be done at the start of the next marking cycle.
1198   // We also know that the STW processor should no longer
1199   // discover any new references.
1200   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1201   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1202   ref_processor_stw()->verify_no_references_recorded();
1203   ref_processor_cm()->verify_no_references_recorded();
1204 }
1205 
1206 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1207   // Post collection logging.
1208   // We should do this after we potentially resize the heap so
1209   // that all the COMMIT / UNCOMMIT events are generated before
1210   // the compaction events.
1211   print_hrm_post_compaction();
1212   heap_transition->print();
1213   print_heap_after_gc();
1214   print_heap_regions();
1215 #ifdef TRACESPINNING
1216   ParallelTaskTerminator::print_termination_counts();
1217 #endif
1218 }
1219 
1220 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1221                                          bool clear_all_soft_refs) {
1222   assert_at_safepoint(true /* should_be_vm_thread */);
1223 
1224   if (GCLocker::check_active_before_gc()) {
1225     // Full GC was not completed.
1226     return false;
1227   }
1228 
1229   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1230       collector_policy()->should_clear_all_soft_refs();
1231 
1232   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1233   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1234 
1235   collector.prepare_collection();
1236   collector.collect();
1237   collector.complete_collection();
1238 
1239   // Full collection was successfully completed.
1240   return true;
1241 }
1242 
1243 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1244   // Currently, there is no facility in the do_full_collection(bool) API to notify
1245   // the caller that the collection did not succeed (e.g., because it was locked
1246   // out by the GC locker). So, right now, we'll ignore the return value.
1247   bool dummy = do_full_collection(true,                /* explicit_gc */
1248                                   clear_all_soft_refs);
1249 }
1250 
1251 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1252   // Capacity, free and used after the GC counted as full regions to
1253   // include the waste in the following calculations.
1254   const size_t capacity_after_gc = capacity();
1255   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1256 
1257   // This is enforced in arguments.cpp.
1258   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1259          "otherwise the code below doesn't make sense");
1260 
1261   // We don't have floating point command-line arguments
1262   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1263   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1264   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1265   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1266 
1267   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1268   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1269 
1270   // We have to be careful here as these two calculations can overflow
1271   // 32-bit size_t's.
1272   double used_after_gc_d = (double) used_after_gc;
1273   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1274   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1275 
1276   // Let's make sure that they are both under the max heap size, which
1277   // by default will make them fit into a size_t.
1278   double desired_capacity_upper_bound = (double) max_heap_size;
1279   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1280                                     desired_capacity_upper_bound);
1281   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1282                                     desired_capacity_upper_bound);
1283 
1284   // We can now safely turn them into size_t's.
1285   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1286   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1287 
1288   // This assert only makes sense here, before we adjust them
1289   // with respect to the min and max heap size.
1290   assert(minimum_desired_capacity <= maximum_desired_capacity,
1291          "minimum_desired_capacity = " SIZE_FORMAT ", "
1292          "maximum_desired_capacity = " SIZE_FORMAT,
1293          minimum_desired_capacity, maximum_desired_capacity);
1294 
1295   // Should not be greater than the heap max size. No need to adjust
1296   // it with respect to the heap min size as it's a lower bound (i.e.,
1297   // we'll try to make the capacity larger than it, not smaller).
1298   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1299   // Should not be less than the heap min size. No need to adjust it
1300   // with respect to the heap max size as it's an upper bound (i.e.,
1301   // we'll try to make the capacity smaller than it, not greater).
1302   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1303 
1304   if (capacity_after_gc < minimum_desired_capacity) {
1305     // Don't expand unless it's significant
1306     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1307 
1308     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1309                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1310                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1311                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1312 
1313     expand(expand_bytes, _workers);
1314 
1315     // No expansion, now see if we want to shrink
1316   } else if (capacity_after_gc > maximum_desired_capacity) {
1317     // Capacity too large, compute shrinking size
1318     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1319 
1320     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1321                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1322                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1323                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1324 
1325     shrink(shrink_bytes);
1326   }
1327 }
1328 
1329 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1330                                                             AllocationContext_t context,
1331                                                             bool do_gc,
1332                                                             bool clear_all_soft_refs,
1333                                                             bool expect_null_mutator_alloc_region,
1334                                                             bool* gc_succeeded) {
1335   *gc_succeeded = true;
1336   // Let's attempt the allocation first.
1337   HeapWord* result =
1338     attempt_allocation_at_safepoint(word_size,
1339                                     context,
1340                                     expect_null_mutator_alloc_region);
1341   if (result != NULL) {
1342     assert(*gc_succeeded, "sanity");
1343     return result;
1344   }
1345 
1346   // In a G1 heap, we're supposed to keep allocation from failing by
1347   // incremental pauses.  Therefore, at least for now, we'll favor
1348   // expansion over collection.  (This might change in the future if we can
1349   // do something smarter than full collection to satisfy a failed alloc.)
1350   result = expand_and_allocate(word_size, context);
1351   if (result != NULL) {
1352     assert(*gc_succeeded, "sanity");
1353     return result;
1354   }
1355 
1356   if (do_gc) {
1357     // Expansion didn't work, we'll try to do a Full GC.
1358     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1359                                        clear_all_soft_refs);
1360   }
1361 
1362   return NULL;
1363 }
1364 
1365 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1366                                                      AllocationContext_t context,
1367                                                      bool* succeeded) {
1368   assert_at_safepoint(true /* should_be_vm_thread */);
1369 
1370   // Attempts to allocate followed by Full GC.
1371   HeapWord* result =
1372     satisfy_failed_allocation_helper(word_size,
1373                                      context,
1374                                      true,  /* do_gc */
1375                                      false, /* clear_all_soft_refs */
1376                                      false, /* expect_null_mutator_alloc_region */
1377                                      succeeded);
1378 
1379   if (result != NULL || !*succeeded) {
1380     return result;
1381   }
1382 
1383   // Attempts to allocate followed by Full GC that will collect all soft references.
1384   result = satisfy_failed_allocation_helper(word_size,
1385                                             context,
1386                                             true, /* do_gc */
1387                                             true, /* clear_all_soft_refs */
1388                                             true, /* expect_null_mutator_alloc_region */
1389                                             succeeded);
1390 
1391   if (result != NULL || !*succeeded) {
1392     return result;
1393   }
1394 
1395   // Attempts to allocate, no GC
1396   result = satisfy_failed_allocation_helper(word_size,
1397                                             context,
1398                                             false, /* do_gc */
1399                                             false, /* clear_all_soft_refs */
1400                                             true,  /* expect_null_mutator_alloc_region */
1401                                             succeeded);
1402 
1403   if (result != NULL) {
1404     assert(*succeeded, "sanity");
1405     return result;
1406   }
1407 
1408   assert(!collector_policy()->should_clear_all_soft_refs(),
1409          "Flag should have been handled and cleared prior to this point");
1410 
1411   // What else?  We might try synchronous finalization later.  If the total
1412   // space available is large enough for the allocation, then a more
1413   // complete compaction phase than we've tried so far might be
1414   // appropriate.
1415   assert(*succeeded, "sanity");
1416   return NULL;
1417 }
1418 
1419 // Attempting to expand the heap sufficiently
1420 // to support an allocation of the given "word_size".  If
1421 // successful, perform the allocation and return the address of the
1422 // allocated block, or else "NULL".
1423 
1424 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1425   assert_at_safepoint(true /* should_be_vm_thread */);
1426 
1427   _verifier->verify_region_sets_optional();
1428 
1429   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1430   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1431                             word_size * HeapWordSize);
1432 
1433 
1434   if (expand(expand_bytes, _workers)) {
1435     _hrm.verify_optional();
1436     _verifier->verify_region_sets_optional();
1437     return attempt_allocation_at_safepoint(word_size,
1438                                            context,
1439                                            false /* expect_null_mutator_alloc_region */);
1440   }
1441   return NULL;
1442 }
1443 
1444 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1445   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1446   aligned_expand_bytes = align_up(aligned_expand_bytes,
1447                                        HeapRegion::GrainBytes);
1448 
1449   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1450                             expand_bytes, aligned_expand_bytes);
1451 
1452   if (is_maximal_no_gc()) {
1453     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1454     return false;
1455   }
1456 
1457   double expand_heap_start_time_sec = os::elapsedTime();
1458   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1459   assert(regions_to_expand > 0, "Must expand by at least one region");
1460 
1461   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1462   if (expand_time_ms != NULL) {
1463     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1464   }
1465 
1466   if (expanded_by > 0) {
1467     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1468     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1469     g1_policy()->record_new_heap_size(num_regions());
1470   } else {
1471     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1472 
1473     // The expansion of the virtual storage space was unsuccessful.
1474     // Let's see if it was because we ran out of swap.
1475     if (G1ExitOnExpansionFailure &&
1476         _hrm.available() >= regions_to_expand) {
1477       // We had head room...
1478       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1479     }
1480   }
1481   return regions_to_expand > 0;
1482 }
1483 
1484 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1485   size_t aligned_shrink_bytes =
1486     ReservedSpace::page_align_size_down(shrink_bytes);
1487   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1488                                          HeapRegion::GrainBytes);
1489   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1490 
1491   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1492   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1493 
1494 
1495   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",
1496                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1497   if (num_regions_removed > 0) {
1498     g1_policy()->record_new_heap_size(num_regions());
1499   } else {
1500     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1501   }
1502 }
1503 
1504 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1505   _verifier->verify_region_sets_optional();
1506 
1507   // We should only reach here at the end of a Full GC which means we
1508   // should not not be holding to any GC alloc regions. The method
1509   // below will make sure of that and do any remaining clean up.
1510   _allocator->abandon_gc_alloc_regions();
1511 
1512   // Instead of tearing down / rebuilding the free lists here, we
1513   // could instead use the remove_all_pending() method on free_list to
1514   // remove only the ones that we need to remove.
1515   tear_down_region_sets(true /* free_list_only */);
1516   shrink_helper(shrink_bytes);
1517   rebuild_region_sets(true /* free_list_only */);
1518 
1519   _hrm.verify_optional();
1520   _verifier->verify_region_sets_optional();
1521 }
1522 
1523 // Public methods.
1524 
1525 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1526   CollectedHeap(),
1527   _young_gen_sampling_thread(NULL),
1528   _collector_policy(collector_policy),





1529   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1530   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1531   _g1_policy(create_g1_policy(_gc_timer_stw)),
1532   _collection_set(this, _g1_policy),
1533   _dirty_card_queue_set(false),
1534   _is_alive_closure_cm(this),
1535   _is_alive_closure_stw(this),
1536   _ref_processor_cm(NULL),
1537   _ref_processor_stw(NULL),
1538   _bot(NULL),
1539   _hot_card_cache(NULL),
1540   _g1_rem_set(NULL),
1541   _cr(NULL),
1542   _g1mm(NULL),
1543   _preserved_marks_set(true /* in_c_heap */),
1544   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1545   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1546   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1547   _humongous_reclaim_candidates(),
1548   _has_humongous_reclaim_candidates(false),
1549   _archive_allocator(NULL),
1550   _free_regions_coming(false),
1551   _gc_time_stamp(0),
1552   _summary_bytes_used(0),
1553   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1554   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1555   _expand_heap_after_alloc_failure(true),
1556   _old_marking_cycles_started(0),
1557   _old_marking_cycles_completed(0),
1558   _in_cset_fast_test() {
1559 
1560   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1561                           /* are_GC_task_threads */true,
1562                           /* are_ConcurrentGC_threads */false);
1563   _workers->initialize_workers();
1564   _verifier = new G1HeapVerifier(this);
1565 
1566   _allocator = G1Allocator::create_allocator(this);
1567 
1568   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1569 
1570   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1571 
1572   // Override the default _filler_array_max_size so that no humongous filler
1573   // objects are created.
1574   _filler_array_max_size = _humongous_object_threshold_in_words;
1575 
1576   uint n_queues = ParallelGCThreads;
1577   _task_queues = new RefToScanQueueSet(n_queues);
1578 
1579   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1580 
1581   for (uint i = 0; i < n_queues; i++) {
1582     RefToScanQueue* q = new RefToScanQueue();
1583     q->initialize();
1584     _task_queues->register_queue(i, q);
1585     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1586   }
1587 
1588   // Initialize the G1EvacuationFailureALot counters and flags.
1589   NOT_PRODUCT(reset_evacuation_should_fail();)
1590 
1591   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1592 }
1593 
1594 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1595                                                                  size_t size,
1596                                                                  size_t translation_factor) {
1597   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1598   // Allocate a new reserved space, preferring to use large pages.
1599   ReservedSpace rs(size, preferred_page_size);
1600   G1RegionToSpaceMapper* result  =
1601     G1RegionToSpaceMapper::create_mapper(rs,
1602                                          size,
1603                                          rs.alignment(),
1604                                          HeapRegion::GrainBytes,
1605                                          translation_factor,
1606                                          mtGC);
1607 
1608   os::trace_page_sizes_for_requested_size(description,
1609                                           size,
1610                                           preferred_page_size,
1611                                           rs.alignment(),
1612                                           rs.base(),
1613                                           rs.size());
1614 
1615   return result;
1616 }
1617 
1618 jint G1CollectedHeap::initialize_concurrent_refinement() {
1619   jint ecode = JNI_OK;
1620   _cr = G1ConcurrentRefine::create(&ecode);
1621   return ecode;
1622 }
1623 
1624 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1625   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1626   if (_young_gen_sampling_thread->osthread() == NULL) {
1627     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1628     return JNI_ENOMEM;
1629   }
1630   return JNI_OK;
1631 }
1632 
1633 jint G1CollectedHeap::initialize() {
1634   CollectedHeap::pre_initialize();
1635   os::enable_vtime();
1636 
1637   // Necessary to satisfy locking discipline assertions.
1638 
1639   MutexLocker x(Heap_lock);
1640 
1641   // While there are no constraints in the GC code that HeapWordSize
1642   // be any particular value, there are multiple other areas in the
1643   // system which believe this to be true (e.g. oop->object_size in some
1644   // cases incorrectly returns the size in wordSize units rather than
1645   // HeapWordSize).
1646   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1647 
1648   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1649   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1650   size_t heap_alignment = collector_policy()->heap_alignment();
1651 
1652   // Ensure that the sizes are properly aligned.
1653   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1654   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1655   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1656 
1657   // Reserve the maximum.
1658 
1659   // When compressed oops are enabled, the preferred heap base
1660   // is calculated by subtracting the requested size from the
1661   // 32Gb boundary and using the result as the base address for
1662   // heap reservation. If the requested size is not aligned to
1663   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1664   // into the ReservedHeapSpace constructor) then the actual
1665   // base of the reserved heap may end up differing from the
1666   // address that was requested (i.e. the preferred heap base).
1667   // If this happens then we could end up using a non-optimal
1668   // compressed oops mode.
1669 
1670   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1671                                                  heap_alignment);
1672 
1673   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1674 
1675   // Create the barrier set for the entire reserved region.
1676   G1SATBCardTableLoggingModRefBS* bs
1677     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1678   bs->initialize();
1679   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1680   set_barrier_set(bs);
1681 
1682   // Create the hot card cache.
1683   _hot_card_cache = new G1HotCardCache(this);
1684 
1685   // Carve out the G1 part of the heap.
1686   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1687   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1688   G1RegionToSpaceMapper* heap_storage =
1689     G1RegionToSpaceMapper::create_mapper(g1_rs,
1690                                          g1_rs.size(),
1691                                          page_size,
1692                                          HeapRegion::GrainBytes,
1693                                          1,
1694                                          mtJavaHeap);
1695   os::trace_page_sizes("Heap",
1696                        collector_policy()->min_heap_byte_size(),
1697                        max_byte_size,
1698                        page_size,
1699                        heap_rs.base(),
1700                        heap_rs.size());
1701   heap_storage->set_mapping_changed_listener(&_listener);
1702 
1703   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1704   G1RegionToSpaceMapper* bot_storage =
1705     create_aux_memory_mapper("Block Offset Table",
1706                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1707                              G1BlockOffsetTable::heap_map_factor());
1708 
1709   G1RegionToSpaceMapper* cardtable_storage =
1710     create_aux_memory_mapper("Card Table",
1711                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1712                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1713 
1714   G1RegionToSpaceMapper* card_counts_storage =
1715     create_aux_memory_mapper("Card Counts Table",
1716                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1717                              G1CardCounts::heap_map_factor());
1718 
1719   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1720   G1RegionToSpaceMapper* prev_bitmap_storage =
1721     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1722   G1RegionToSpaceMapper* next_bitmap_storage =
1723     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1724 
1725   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1726   g1_barrier_set()->initialize(cardtable_storage);
1727   // Do later initialization work for concurrent refinement.
1728   _hot_card_cache->initialize(card_counts_storage);
1729 
1730   // 6843694 - ensure that the maximum region index can fit
1731   // in the remembered set structures.
1732   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1733   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1734 
1735   // Also create a G1 rem set.
1736   _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1737   _g1_rem_set->initialize(max_capacity(), max_regions());
1738 
1739   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1740   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1741   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1742             "too many cards per region");
1743 
1744   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1745 
1746   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1747 
1748   {
1749     HeapWord* start = _hrm.reserved().start();
1750     HeapWord* end = _hrm.reserved().end();
1751     size_t granularity = HeapRegion::GrainBytes;
1752 
1753     _in_cset_fast_test.initialize(start, end, granularity);
1754     _humongous_reclaim_candidates.initialize(start, end, granularity);
1755   }
1756 
1757   // Create the G1ConcurrentMark data structure and thread.
1758   // (Must do this late, so that "max_regions" is defined.)
1759   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1760   if (_cm == NULL || !_cm->completed_initialization()) {
1761     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1762     return JNI_ENOMEM;
1763   }
1764   _cmThread = _cm->cm_thread();
1765 
1766   // Now expand into the initial heap size.
1767   if (!expand(init_byte_size, _workers)) {
1768     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1769     return JNI_ENOMEM;
1770   }
1771 
1772   // Perform any initialization actions delegated to the policy.
1773   g1_policy()->init(this, &_collection_set);
1774 
1775   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1776                                                SATB_Q_FL_lock,
1777                                                G1SATBProcessCompletedThreshold,
1778                                                Shared_SATB_Q_lock);
1779 
1780   jint ecode = initialize_concurrent_refinement();
1781   if (ecode != JNI_OK) {
1782     return ecode;
1783   }
1784 
1785   ecode = initialize_young_gen_sampling_thread();
1786   if (ecode != JNI_OK) {
1787     return ecode;
1788   }
1789 
1790   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1791                                                 DirtyCardQ_FL_lock,
1792                                                 (int)concurrent_refine()->yellow_zone(),
1793                                                 (int)concurrent_refine()->red_zone(),
1794                                                 Shared_DirtyCardQ_lock,
1795                                                 NULL,  // fl_owner
1796                                                 true); // init_free_ids
1797 
1798   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1799                                     DirtyCardQ_FL_lock,
1800                                     -1, // never trigger processing
1801                                     -1, // no limit on length
1802                                     Shared_DirtyCardQ_lock,
1803                                     &JavaThread::dirty_card_queue_set());
1804 
1805   // Here we allocate the dummy HeapRegion that is required by the
1806   // G1AllocRegion class.
1807   HeapRegion* dummy_region = _hrm.get_dummy_region();
1808 
1809   // We'll re-use the same region whether the alloc region will
1810   // require BOT updates or not and, if it doesn't, then a non-young
1811   // region will complain that it cannot support allocations without
1812   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1813   dummy_region->set_eden();
1814   // Make sure it's full.
1815   dummy_region->set_top(dummy_region->end());
1816   G1AllocRegion::setup(this, dummy_region);
1817 
1818   _allocator->init_mutator_alloc_region();
1819 
1820   // Do create of the monitoring and management support so that
1821   // values in the heap have been properly initialized.
1822   _g1mm = new G1MonitoringSupport(this);
1823 











1824   G1StringDedup::initialize();
1825 
1826   _preserved_marks_set.init(ParallelGCThreads);
1827 
1828   _collection_set.initialize(max_regions());
1829 
1830   return JNI_OK;
1831 }
1832 
1833 void G1CollectedHeap::stop() {
1834   // Stop all concurrent threads. We do this to make sure these threads
1835   // do not continue to execute and access resources (e.g. logging)
1836   // that are destroyed during shutdown.
1837   _cr->stop();
1838   _young_gen_sampling_thread->stop();
1839   _cmThread->stop();
1840   if (G1StringDedup::is_enabled()) {
1841     G1StringDedup::stop();
1842   }
1843 }
1844 
1845 void G1CollectedHeap::safepoint_synchronize_begin() {
1846   SuspendibleThreadSet::synchronize();
1847 }
1848 
1849 void G1CollectedHeap::safepoint_synchronize_end() {
1850   SuspendibleThreadSet::desynchronize();
1851 }
1852 
1853 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1854   return HeapRegion::max_region_size();
1855 }
1856 
1857 void G1CollectedHeap::post_initialize() {
1858   ref_processing_init();
1859 }
1860 
1861 void G1CollectedHeap::ref_processing_init() {
1862   // Reference processing in G1 currently works as follows:
1863   //
1864   // * There are two reference processor instances. One is
1865   //   used to record and process discovered references
1866   //   during concurrent marking; the other is used to
1867   //   record and process references during STW pauses
1868   //   (both full and incremental).
1869   // * Both ref processors need to 'span' the entire heap as
1870   //   the regions in the collection set may be dotted around.
1871   //
1872   // * For the concurrent marking ref processor:
1873   //   * Reference discovery is enabled at initial marking.
1874   //   * Reference discovery is disabled and the discovered
1875   //     references processed etc during remarking.
1876   //   * Reference discovery is MT (see below).
1877   //   * Reference discovery requires a barrier (see below).
1878   //   * Reference processing may or may not be MT
1879   //     (depending on the value of ParallelRefProcEnabled
1880   //     and ParallelGCThreads).
1881   //   * A full GC disables reference discovery by the CM
1882   //     ref processor and abandons any entries on it's
1883   //     discovered lists.
1884   //
1885   // * For the STW processor:
1886   //   * Non MT discovery is enabled at the start of a full GC.
1887   //   * Processing and enqueueing during a full GC is non-MT.
1888   //   * During a full GC, references are processed after marking.
1889   //
1890   //   * Discovery (may or may not be MT) is enabled at the start
1891   //     of an incremental evacuation pause.
1892   //   * References are processed near the end of a STW evacuation pause.
1893   //   * For both types of GC:
1894   //     * Discovery is atomic - i.e. not concurrent.
1895   //     * Reference discovery will not need a barrier.
1896 
1897   MemRegion mr = reserved_region();
1898 
1899   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1900 
1901   // Concurrent Mark ref processor
1902   _ref_processor_cm =
1903     new ReferenceProcessor(mr,    // span
1904                            mt_processing,
1905                                 // mt processing
1906                            ParallelGCThreads,
1907                                 // degree of mt processing
1908                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1909                                 // mt discovery
1910                            MAX2(ParallelGCThreads, ConcGCThreads),
1911                                 // degree of mt discovery
1912                            false,
1913                                 // Reference discovery is not atomic
1914                            &_is_alive_closure_cm);
1915                                 // is alive closure
1916                                 // (for efficiency/performance)
1917 
1918   // STW ref processor
1919   _ref_processor_stw =
1920     new ReferenceProcessor(mr,    // span
1921                            mt_processing,
1922                                 // mt processing
1923                            ParallelGCThreads,
1924                                 // degree of mt processing
1925                            (ParallelGCThreads > 1),
1926                                 // mt discovery
1927                            ParallelGCThreads,
1928                                 // degree of mt discovery
1929                            true,
1930                                 // Reference discovery is atomic
1931                            &_is_alive_closure_stw);
1932                                 // is alive closure
1933                                 // (for efficiency/performance)
1934 }
1935 
1936 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1937   return _collector_policy;
1938 }
1939 
1940 size_t G1CollectedHeap::capacity() const {
1941   return _hrm.length() * HeapRegion::GrainBytes;
1942 }
1943 
1944 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1945   return _hrm.total_free_bytes();
1946 }
1947 
1948 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1949   hr->reset_gc_time_stamp();
1950 }
1951 
1952 #ifndef PRODUCT
1953 
1954 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1955 private:
1956   unsigned _gc_time_stamp;
1957   bool _failures;
1958 
1959 public:
1960   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1961     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1962 
1963   virtual bool doHeapRegion(HeapRegion* hr) {
1964     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1965     if (_gc_time_stamp != region_gc_time_stamp) {
1966       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1967                             region_gc_time_stamp, _gc_time_stamp);
1968       _failures = true;
1969     }
1970     return false;
1971   }
1972 
1973   bool failures() { return _failures; }
1974 };
1975 
1976 void G1CollectedHeap::check_gc_time_stamps() {
1977   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1978   heap_region_iterate(&cl);
1979   guarantee(!cl.failures(), "all GC time stamps should have been reset");
1980 }
1981 #endif // PRODUCT
1982 
1983 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1984   _hot_card_cache->drain(cl, worker_i);
1985 }
1986 
1987 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1988   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1989   size_t n_completed_buffers = 0;
1990   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1991     n_completed_buffers++;
1992   }
1993   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1994   dcqs.clear_n_completed_buffers();
1995   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1996 }
1997 
1998 // Computes the sum of the storage used by the various regions.
1999 size_t G1CollectedHeap::used() const {
2000   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2001   if (_archive_allocator != NULL) {
2002     result += _archive_allocator->used();
2003   }
2004   return result;
2005 }
2006 
2007 size_t G1CollectedHeap::used_unlocked() const {
2008   return _summary_bytes_used;
2009 }
2010 
2011 class SumUsedClosure: public HeapRegionClosure {
2012   size_t _used;
2013 public:
2014   SumUsedClosure() : _used(0) {}
2015   bool doHeapRegion(HeapRegion* r) {
2016     _used += r->used();
2017     return false;
2018   }
2019   size_t result() { return _used; }
2020 };
2021 
2022 size_t G1CollectedHeap::recalculate_used() const {
2023   double recalculate_used_start = os::elapsedTime();
2024 
2025   SumUsedClosure blk;
2026   heap_region_iterate(&blk);
2027 
2028   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2029   return blk.result();
2030 }
2031 
2032 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2033   switch (cause) {
2034     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2035     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2036     case GCCause::_update_allocation_context_stats_inc: return true;
2037     case GCCause::_wb_conc_mark:                        return true;
2038     default :                                           return false;
2039   }
2040 }
2041 
2042 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2043   switch (cause) {
2044     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2045     case GCCause::_g1_humongous_allocation: return true;
2046     default:                                return is_user_requested_concurrent_full_gc(cause);
2047   }
2048 }
2049 
2050 #ifndef PRODUCT
2051 void G1CollectedHeap::allocate_dummy_regions() {
2052   // Let's fill up most of the region
2053   size_t word_size = HeapRegion::GrainWords - 1024;
2054   // And as a result the region we'll allocate will be humongous.
2055   guarantee(is_humongous(word_size), "sanity");
2056 
2057   // _filler_array_max_size is set to humongous object threshold
2058   // but temporarily change it to use CollectedHeap::fill_with_object().
2059   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2060 
2061   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2062     // Let's use the existing mechanism for the allocation
2063     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2064                                                  AllocationContext::system());
2065     if (dummy_obj != NULL) {
2066       MemRegion mr(dummy_obj, word_size);
2067       CollectedHeap::fill_with_object(mr);
2068     } else {
2069       // If we can't allocate once, we probably cannot allocate
2070       // again. Let's get out of the loop.
2071       break;
2072     }
2073   }
2074 }
2075 #endif // !PRODUCT
2076 
2077 void G1CollectedHeap::increment_old_marking_cycles_started() {
2078   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2079          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2080          "Wrong marking cycle count (started: %d, completed: %d)",
2081          _old_marking_cycles_started, _old_marking_cycles_completed);
2082 
2083   _old_marking_cycles_started++;
2084 }
2085 
2086 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2087   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2088 
2089   // We assume that if concurrent == true, then the caller is a
2090   // concurrent thread that was joined the Suspendible Thread
2091   // Set. If there's ever a cheap way to check this, we should add an
2092   // assert here.
2093 
2094   // Given that this method is called at the end of a Full GC or of a
2095   // concurrent cycle, and those can be nested (i.e., a Full GC can
2096   // interrupt a concurrent cycle), the number of full collections
2097   // completed should be either one (in the case where there was no
2098   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2099   // behind the number of full collections started.
2100 
2101   // This is the case for the inner caller, i.e. a Full GC.
2102   assert(concurrent ||
2103          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2104          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2105          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2106          "is inconsistent with _old_marking_cycles_completed = %u",
2107          _old_marking_cycles_started, _old_marking_cycles_completed);
2108 
2109   // This is the case for the outer caller, i.e. the concurrent cycle.
2110   assert(!concurrent ||
2111          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2112          "for outer caller (concurrent cycle): "
2113          "_old_marking_cycles_started = %u "
2114          "is inconsistent with _old_marking_cycles_completed = %u",
2115          _old_marking_cycles_started, _old_marking_cycles_completed);
2116 
2117   _old_marking_cycles_completed += 1;
2118 
2119   // We need to clear the "in_progress" flag in the CM thread before
2120   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2121   // is set) so that if a waiter requests another System.gc() it doesn't
2122   // incorrectly see that a marking cycle is still in progress.
2123   if (concurrent) {
2124     _cmThread->set_idle();
2125   }
2126 
2127   // This notify_all() will ensure that a thread that called
2128   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2129   // and it's waiting for a full GC to finish will be woken up. It is
2130   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2131   FullGCCount_lock->notify_all();
2132 }
2133 
2134 void G1CollectedHeap::collect(GCCause::Cause cause) {
2135   assert_heap_not_locked();
2136 
2137   uint gc_count_before;
2138   uint old_marking_count_before;
2139   uint full_gc_count_before;
2140   bool retry_gc;
2141 
2142   do {
2143     retry_gc = false;
2144 
2145     {
2146       MutexLocker ml(Heap_lock);
2147 
2148       // Read the GC count while holding the Heap_lock
2149       gc_count_before = total_collections();
2150       full_gc_count_before = total_full_collections();
2151       old_marking_count_before = _old_marking_cycles_started;
2152     }
2153 
2154     if (should_do_concurrent_full_gc(cause)) {
2155       // Schedule an initial-mark evacuation pause that will start a
2156       // concurrent cycle. We're setting word_size to 0 which means that
2157       // we are not requesting a post-GC allocation.
2158       VM_G1IncCollectionPause op(gc_count_before,
2159                                  0,     /* word_size */
2160                                  true,  /* should_initiate_conc_mark */
2161                                  g1_policy()->max_pause_time_ms(),
2162                                  cause);
2163       op.set_allocation_context(AllocationContext::current());
2164 
2165       VMThread::execute(&op);
2166       if (!op.pause_succeeded()) {
2167         if (old_marking_count_before == _old_marking_cycles_started) {
2168           retry_gc = op.should_retry_gc();
2169         } else {
2170           // A Full GC happened while we were trying to schedule the
2171           // initial-mark GC. No point in starting a new cycle given
2172           // that the whole heap was collected anyway.
2173         }
2174 
2175         if (retry_gc) {
2176           if (GCLocker::is_active_and_needs_gc()) {
2177             GCLocker::stall_until_clear();
2178           }
2179         }
2180       }
2181     } else {
2182       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2183           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2184 
2185         // Schedule a standard evacuation pause. We're setting word_size
2186         // to 0 which means that we are not requesting a post-GC allocation.
2187         VM_G1IncCollectionPause op(gc_count_before,
2188                                    0,     /* word_size */
2189                                    false, /* should_initiate_conc_mark */
2190                                    g1_policy()->max_pause_time_ms(),
2191                                    cause);
2192         VMThread::execute(&op);
2193       } else {
2194         // Schedule a Full GC.
2195         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2196         VMThread::execute(&op);
2197       }
2198     }
2199   } while (retry_gc);
2200 }
2201 
2202 bool G1CollectedHeap::is_in(const void* p) const {
2203   if (_hrm.reserved().contains(p)) {
2204     // Given that we know that p is in the reserved space,
2205     // heap_region_containing() should successfully
2206     // return the containing region.
2207     HeapRegion* hr = heap_region_containing(p);
2208     return hr->is_in(p);
2209   } else {
2210     return false;
2211   }
2212 }
2213 
2214 #ifdef ASSERT
2215 bool G1CollectedHeap::is_in_exact(const void* p) const {
2216   bool contains = reserved_region().contains(p);
2217   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2218   if (contains && available) {
2219     return true;
2220   } else {
2221     return false;
2222   }
2223 }
2224 #endif
2225 
2226 // Iteration functions.
2227 
2228 // Iterates an ObjectClosure over all objects within a HeapRegion.
2229 
2230 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2231   ObjectClosure* _cl;
2232 public:
2233   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2234   bool doHeapRegion(HeapRegion* r) {
2235     if (!r->is_continues_humongous()) {
2236       r->object_iterate(_cl);
2237     }
2238     return false;
2239   }
2240 };
2241 
2242 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2243   IterateObjectClosureRegionClosure blk(cl);
2244   heap_region_iterate(&blk);
2245 }
2246 
2247 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2248   _hrm.iterate(cl);
2249 }
2250 
2251 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2252                                                                  HeapRegionClaimer *hrclaimer,
2253                                                                  uint worker_id) const {
2254   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2255 }
2256 
2257 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2258                                                          HeapRegionClaimer *hrclaimer) const {
2259   _hrm.par_iterate(cl, hrclaimer, 0);
2260 }
2261 
2262 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2263   _collection_set.iterate(cl);
2264 }
2265 
2266 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2267   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2268 }
2269 
2270 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2271   HeapRegion* hr = heap_region_containing(addr);
2272   return hr->block_start(addr);
2273 }
2274 
2275 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2276   HeapRegion* hr = heap_region_containing(addr);
2277   return hr->block_size(addr);
2278 }
2279 
2280 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2281   HeapRegion* hr = heap_region_containing(addr);
2282   return hr->block_is_obj(addr);
2283 }
2284 
2285 bool G1CollectedHeap::supports_tlab_allocation() const {
2286   return true;
2287 }
2288 
2289 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2290   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2291 }
2292 
2293 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2294   return _eden.length() * HeapRegion::GrainBytes;
2295 }
2296 
2297 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2298 // must be equal to the humongous object limit.
2299 size_t G1CollectedHeap::max_tlab_size() const {
2300   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2301 }
2302 
2303 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2304   AllocationContext_t context = AllocationContext::current();
2305   return _allocator->unsafe_max_tlab_alloc(context);
2306 }
2307 
2308 size_t G1CollectedHeap::max_capacity() const {
2309   return _hrm.reserved().byte_size();
2310 }
2311 
2312 jlong G1CollectedHeap::millis_since_last_gc() {
2313   // See the notes in GenCollectedHeap::millis_since_last_gc()
2314   // for more information about the implementation.
2315   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2316     _g1_policy->collection_pause_end_millis();
2317   if (ret_val < 0) {
2318     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2319       ". returning zero instead.", ret_val);
2320     return 0;
2321   }
2322   return ret_val;
2323 }
2324 
2325 void G1CollectedHeap::prepare_for_verify() {
2326   _verifier->prepare_for_verify();
2327 }
2328 
2329 void G1CollectedHeap::verify(VerifyOption vo) {
2330   _verifier->verify(vo);
2331 }
2332 
2333 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2334   return true;
2335 }
2336 
2337 const char* const* G1CollectedHeap::concurrent_phases() const {
2338   return _cmThread->concurrent_phases();
2339 }
2340 
2341 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2342   return _cmThread->request_concurrent_phase(phase);
2343 }
2344 
2345 class PrintRegionClosure: public HeapRegionClosure {
2346   outputStream* _st;
2347 public:
2348   PrintRegionClosure(outputStream* st) : _st(st) {}
2349   bool doHeapRegion(HeapRegion* r) {
2350     r->print_on(_st);
2351     return false;
2352   }
2353 };
2354 
2355 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2356                                        const HeapRegion* hr,
2357                                        const VerifyOption vo) const {
2358   switch (vo) {
2359   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2360   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2361   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2362   default:                            ShouldNotReachHere();
2363   }
2364   return false; // keep some compilers happy
2365 }
2366 
2367 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2368                                        const VerifyOption vo) const {
2369   switch (vo) {
2370   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2371   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2372   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2373   default:                            ShouldNotReachHere();
2374   }
2375   return false; // keep some compilers happy
2376 }
2377 
2378 void G1CollectedHeap::print_heap_regions() const {
2379   LogTarget(Trace, gc, heap, region) lt;
2380   if (lt.is_enabled()) {
2381     LogStream ls(lt);
2382     print_regions_on(&ls);
2383   }
2384 }
2385 
2386 void G1CollectedHeap::print_on(outputStream* st) const {
2387   st->print(" %-20s", "garbage-first heap");
2388   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2389             capacity()/K, used_unlocked()/K);
2390   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2391             p2i(_hrm.reserved().start()),
2392             p2i(_hrm.reserved().end()));
2393   st->cr();
2394   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2395   uint young_regions = young_regions_count();
2396   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2397             (size_t) young_regions * HeapRegion::GrainBytes / K);
2398   uint survivor_regions = survivor_regions_count();
2399   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2400             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2401   st->cr();
2402   MetaspaceAux::print_on(st);
2403 }
2404 
2405 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2406   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2407                "HS=humongous(starts), HC=humongous(continues), "
2408                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2409                "AC=allocation context, "
2410                "TAMS=top-at-mark-start (previous, next)");
2411   PrintRegionClosure blk(st);
2412   heap_region_iterate(&blk);
2413 }
2414 
2415 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2416   print_on(st);
2417 
2418   // Print the per-region information.
2419   print_regions_on(st);
2420 }
2421 
2422 void G1CollectedHeap::print_on_error(outputStream* st) const {
2423   this->CollectedHeap::print_on_error(st);
2424 
2425   if (_cm != NULL) {
2426     st->cr();
2427     _cm->print_on_error(st);
2428   }
2429 }
2430 
2431 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2432   workers()->print_worker_threads_on(st);
2433   _cmThread->print_on(st);
2434   st->cr();
2435   _cm->print_worker_threads_on(st);
2436   _cr->print_threads_on(st);
2437   _young_gen_sampling_thread->print_on(st);
2438   if (G1StringDedup::is_enabled()) {
2439     G1StringDedup::print_worker_threads_on(st);
2440   }
2441 }
2442 
2443 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2444   workers()->threads_do(tc);
2445   tc->do_thread(_cmThread);
2446   _cm->threads_do(tc);
2447   _cr->threads_do(tc);
2448   tc->do_thread(_young_gen_sampling_thread);
2449   if (G1StringDedup::is_enabled()) {
2450     G1StringDedup::threads_do(tc);
2451   }
2452 }
2453 
2454 void G1CollectedHeap::print_tracing_info() const {
2455   g1_rem_set()->print_summary_info();
2456   concurrent_mark()->print_summary_info();
2457 }
2458 
2459 #ifndef PRODUCT
2460 // Helpful for debugging RSet issues.
2461 
2462 class PrintRSetsClosure : public HeapRegionClosure {
2463 private:
2464   const char* _msg;
2465   size_t _occupied_sum;
2466 
2467 public:
2468   bool doHeapRegion(HeapRegion* r) {
2469     HeapRegionRemSet* hrrs = r->rem_set();
2470     size_t occupied = hrrs->occupied();
2471     _occupied_sum += occupied;
2472 
2473     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2474     if (occupied == 0) {
2475       tty->print_cr("  RSet is empty");
2476     } else {
2477       hrrs->print();
2478     }
2479     tty->print_cr("----------");
2480     return false;
2481   }
2482 
2483   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2484     tty->cr();
2485     tty->print_cr("========================================");
2486     tty->print_cr("%s", msg);
2487     tty->cr();
2488   }
2489 
2490   ~PrintRSetsClosure() {
2491     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2492     tty->print_cr("========================================");
2493     tty->cr();
2494   }
2495 };
2496 
2497 void G1CollectedHeap::print_cset_rsets() {
2498   PrintRSetsClosure cl("Printing CSet RSets");
2499   collection_set_iterate(&cl);
2500 }
2501 
2502 void G1CollectedHeap::print_all_rsets() {
2503   PrintRSetsClosure cl("Printing All RSets");;
2504   heap_region_iterate(&cl);
2505 }
2506 #endif // PRODUCT
2507 
2508 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2509 
2510   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2511   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2512   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2513 
2514   size_t eden_capacity_bytes =
2515     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2516 
2517   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2518   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2519                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2520 }
2521 
2522 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2523   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2524                        stats->unused(), stats->used(), stats->region_end_waste(),
2525                        stats->regions_filled(), stats->direct_allocated(),
2526                        stats->failure_used(), stats->failure_waste());
2527 }
2528 
2529 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2530   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2531   gc_tracer->report_gc_heap_summary(when, heap_summary);
2532 
2533   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2534   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2535 }
2536 
2537 G1CollectedHeap* G1CollectedHeap::heap() {
2538   CollectedHeap* heap = Universe::heap();
2539   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2540   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2541   return (G1CollectedHeap*)heap;
2542 }
2543 
2544 void G1CollectedHeap::gc_prologue(bool full) {
2545   // always_do_update_barrier = false;
2546   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2547 
2548   // This summary needs to be printed before incrementing total collections.
2549   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2550 
2551   // Update common counters.
2552   increment_total_collections(full /* full gc */);
2553   if (full) {
2554     increment_old_marking_cycles_started();
2555     reset_gc_time_stamp();
2556   } else {
2557     increment_gc_time_stamp();
2558   }
2559 
2560   // Fill TLAB's and such
2561   double start = os::elapsedTime();
2562   accumulate_statistics_all_tlabs();
2563   ensure_parsability(true);
2564   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2565 }
2566 
2567 void G1CollectedHeap::gc_epilogue(bool full) {
2568   // Update common counters.
2569   if (full) {
2570     // Update the number of full collections that have been completed.
2571     increment_old_marking_cycles_completed(false /* concurrent */);
2572   }
2573 
2574   // We are at the end of the GC. Total collections has already been increased.
2575   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2576 
2577   // FIXME: what is this about?
2578   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2579   // is set.
2580 #if COMPILER2_OR_JVMCI
2581   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2582 #endif
2583   // always_do_update_barrier = true;
2584 
2585   double start = os::elapsedTime();
2586   resize_all_tlabs();
2587   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2588 
2589   allocation_context_stats().update(full);
2590 
2591   MemoryService::track_memory_usage();
2592   // We have just completed a GC. Update the soft reference
2593   // policy with the new heap occupancy
2594   Universe::update_heap_info_at_gc();
2595 }
2596 
2597 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2598                                                uint gc_count_before,
2599                                                bool* succeeded,
2600                                                GCCause::Cause gc_cause) {
2601   assert_heap_not_locked_and_not_at_safepoint();
2602   VM_G1IncCollectionPause op(gc_count_before,
2603                              word_size,
2604                              false, /* should_initiate_conc_mark */
2605                              g1_policy()->max_pause_time_ms(),
2606                              gc_cause);
2607 
2608   op.set_allocation_context(AllocationContext::current());
2609   VMThread::execute(&op);
2610 
2611   HeapWord* result = op.result();
2612   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2613   assert(result == NULL || ret_succeeded,
2614          "the result should be NULL if the VM did not succeed");
2615   *succeeded = ret_succeeded;
2616 
2617   assert_heap_not_locked();
2618   return result;
2619 }
2620 
2621 void
2622 G1CollectedHeap::doConcurrentMark() {
2623   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2624   if (!_cmThread->in_progress()) {
2625     _cmThread->set_started();
2626     CGC_lock->notify();
2627   }
2628 }
2629 
2630 size_t G1CollectedHeap::pending_card_num() {
2631   size_t extra_cards = 0;
2632   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2633     DirtyCardQueue& dcq = curr->dirty_card_queue();
2634     extra_cards += dcq.size();
2635   }
2636   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2637   size_t buffer_size = dcqs.buffer_size();
2638   size_t buffer_num = dcqs.completed_buffers_num();
2639 
2640   return buffer_size * buffer_num + extra_cards;
2641 }
2642 
2643 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2644  private:
2645   size_t _total_humongous;
2646   size_t _candidate_humongous;
2647 
2648   DirtyCardQueue _dcq;
2649 
2650   // We don't nominate objects with many remembered set entries, on
2651   // the assumption that such objects are likely still live.
2652   bool is_remset_small(HeapRegion* region) const {
2653     HeapRegionRemSet* const rset = region->rem_set();
2654     return G1EagerReclaimHumongousObjectsWithStaleRefs
2655       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2656       : rset->is_empty();
2657   }
2658 
2659   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2660     assert(region->is_starts_humongous(), "Must start a humongous object");
2661 
2662     oop obj = oop(region->bottom());
2663 
2664     // Dead objects cannot be eager reclaim candidates. Due to class
2665     // unloading it is unsafe to query their classes so we return early.
2666     if (heap->is_obj_dead(obj, region)) {
2667       return false;
2668     }
2669 
2670     // Candidate selection must satisfy the following constraints
2671     // while concurrent marking is in progress:
2672     //
2673     // * In order to maintain SATB invariants, an object must not be
2674     // reclaimed if it was allocated before the start of marking and
2675     // has not had its references scanned.  Such an object must have
2676     // its references (including type metadata) scanned to ensure no
2677     // live objects are missed by the marking process.  Objects
2678     // allocated after the start of concurrent marking don't need to
2679     // be scanned.
2680     //
2681     // * An object must not be reclaimed if it is on the concurrent
2682     // mark stack.  Objects allocated after the start of concurrent
2683     // marking are never pushed on the mark stack.
2684     //
2685     // Nominating only objects allocated after the start of concurrent
2686     // marking is sufficient to meet both constraints.  This may miss
2687     // some objects that satisfy the constraints, but the marking data
2688     // structures don't support efficiently performing the needed
2689     // additional tests or scrubbing of the mark stack.
2690     //
2691     // However, we presently only nominate is_typeArray() objects.
2692     // A humongous object containing references induces remembered
2693     // set entries on other regions.  In order to reclaim such an
2694     // object, those remembered sets would need to be cleaned up.
2695     //
2696     // We also treat is_typeArray() objects specially, allowing them
2697     // to be reclaimed even if allocated before the start of
2698     // concurrent mark.  For this we rely on mark stack insertion to
2699     // exclude is_typeArray() objects, preventing reclaiming an object
2700     // that is in the mark stack.  We also rely on the metadata for
2701     // such objects to be built-in and so ensured to be kept live.
2702     // Frequent allocation and drop of large binary blobs is an
2703     // important use case for eager reclaim, and this special handling
2704     // may reduce needed headroom.
2705 
2706     return obj->is_typeArray() && is_remset_small(region);
2707   }
2708 
2709  public:
2710   RegisterHumongousWithInCSetFastTestClosure()
2711   : _total_humongous(0),
2712     _candidate_humongous(0),
2713     _dcq(&JavaThread::dirty_card_queue_set()) {
2714   }
2715 
2716   virtual bool doHeapRegion(HeapRegion* r) {
2717     if (!r->is_starts_humongous()) {
2718       return false;
2719     }
2720     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2721 
2722     bool is_candidate = humongous_region_is_candidate(g1h, r);
2723     uint rindex = r->hrm_index();
2724     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2725     if (is_candidate) {
2726       _candidate_humongous++;
2727       g1h->register_humongous_region_with_cset(rindex);
2728       // Is_candidate already filters out humongous object with large remembered sets.
2729       // If we have a humongous object with a few remembered sets, we simply flush these
2730       // remembered set entries into the DCQS. That will result in automatic
2731       // re-evaluation of their remembered set entries during the following evacuation
2732       // phase.
2733       if (!r->rem_set()->is_empty()) {
2734         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2735                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2736         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2737         HeapRegionRemSetIterator hrrs(r->rem_set());
2738         size_t card_index;
2739         while (hrrs.has_next(card_index)) {
2740           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2741           // The remembered set might contain references to already freed
2742           // regions. Filter out such entries to avoid failing card table
2743           // verification.
2744           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2745             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2746               *card_ptr = CardTableModRefBS::dirty_card_val();
2747               _dcq.enqueue(card_ptr);
2748             }
2749           }
2750         }
2751         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2752                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2753                hrrs.n_yielded(), r->rem_set()->occupied());
2754         r->rem_set()->clear_locked();
2755       }
2756       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2757     }
2758     _total_humongous++;
2759 
2760     return false;
2761   }
2762 
2763   size_t total_humongous() const { return _total_humongous; }
2764   size_t candidate_humongous() const { return _candidate_humongous; }
2765 
2766   void flush_rem_set_entries() { _dcq.flush(); }
2767 };
2768 
2769 void G1CollectedHeap::register_humongous_regions_with_cset() {
2770   if (!G1EagerReclaimHumongousObjects) {
2771     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2772     return;
2773   }
2774   double time = os::elapsed_counter();
2775 
2776   // Collect reclaim candidate information and register candidates with cset.
2777   RegisterHumongousWithInCSetFastTestClosure cl;
2778   heap_region_iterate(&cl);
2779 
2780   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2781   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2782                                                                   cl.total_humongous(),
2783                                                                   cl.candidate_humongous());
2784   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2785 
2786   // Finally flush all remembered set entries to re-check into the global DCQS.
2787   cl.flush_rem_set_entries();
2788 }
2789 
2790 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2791   public:
2792     bool doHeapRegion(HeapRegion* hr) {
2793       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2794         hr->verify_rem_set();
2795       }
2796       return false;
2797     }
2798 };
2799 
2800 uint G1CollectedHeap::num_task_queues() const {
2801   return _task_queues->size();
2802 }
2803 
2804 #if TASKQUEUE_STATS
2805 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2806   st->print_raw_cr("GC Task Stats");
2807   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2808   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2809 }
2810 
2811 void G1CollectedHeap::print_taskqueue_stats() const {
2812   if (!log_is_enabled(Trace, gc, task, stats)) {
2813     return;
2814   }
2815   Log(gc, task, stats) log;
2816   ResourceMark rm;
2817   LogStream ls(log.trace());
2818   outputStream* st = &ls;
2819 
2820   print_taskqueue_stats_hdr(st);
2821 
2822   TaskQueueStats totals;
2823   const uint n = num_task_queues();
2824   for (uint i = 0; i < n; ++i) {
2825     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2826     totals += task_queue(i)->stats;
2827   }
2828   st->print_raw("tot "); totals.print(st); st->cr();
2829 
2830   DEBUG_ONLY(totals.verify());
2831 }
2832 
2833 void G1CollectedHeap::reset_taskqueue_stats() {
2834   const uint n = num_task_queues();
2835   for (uint i = 0; i < n; ++i) {
2836     task_queue(i)->stats.reset();
2837   }
2838 }
2839 #endif // TASKQUEUE_STATS
2840 
2841 void G1CollectedHeap::wait_for_root_region_scanning() {
2842   double scan_wait_start = os::elapsedTime();
2843   // We have to wait until the CM threads finish scanning the
2844   // root regions as it's the only way to ensure that all the
2845   // objects on them have been correctly scanned before we start
2846   // moving them during the GC.
2847   bool waited = _cm->root_regions()->wait_until_scan_finished();
2848   double wait_time_ms = 0.0;
2849   if (waited) {
2850     double scan_wait_end = os::elapsedTime();
2851     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2852   }
2853   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2854 }
2855 
2856 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2857 private:
2858   G1HRPrinter* _hr_printer;
2859 public:
2860   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2861 
2862   virtual bool doHeapRegion(HeapRegion* r) {
2863     _hr_printer->cset(r);
2864     return false;
2865   }
2866 };
2867 
2868 void G1CollectedHeap::start_new_collection_set() {
2869   collection_set()->start_incremental_building();
2870 
2871   clear_cset_fast_test();
2872 
2873   guarantee(_eden.length() == 0, "eden should have been cleared");
2874   g1_policy()->transfer_survivors_to_cset(survivor());
2875 }
2876 
2877 bool
2878 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2879   assert_at_safepoint(true /* should_be_vm_thread */);
2880   guarantee(!is_gc_active(), "collection is not reentrant");
2881 
2882   if (GCLocker::check_active_before_gc()) {
2883     return false;
2884   }
2885 
2886   _gc_timer_stw->register_gc_start();
2887 
2888   GCIdMark gc_id_mark;
2889   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2890 
2891   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2892   ResourceMark rm;
2893 
2894   g1_policy()->note_gc_start();
2895 
2896   wait_for_root_region_scanning();
2897 
2898   print_heap_before_gc();
2899   print_heap_regions();
2900   trace_heap_before_gc(_gc_tracer_stw);
2901 
2902   _verifier->verify_region_sets_optional();
2903   _verifier->verify_dirty_young_regions();
2904 
2905   // We should not be doing initial mark unless the conc mark thread is running
2906   if (!_cmThread->should_terminate()) {
2907     // This call will decide whether this pause is an initial-mark
2908     // pause. If it is, during_initial_mark_pause() will return true
2909     // for the duration of this pause.
2910     g1_policy()->decide_on_conc_mark_initiation();
2911   }
2912 
2913   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2914   assert(!collector_state()->during_initial_mark_pause() ||
2915           collector_state()->gcs_are_young(), "sanity");
2916 
2917   // We also do not allow mixed GCs during marking.
2918   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2919 
2920   // Record whether this pause is an initial mark. When the current
2921   // thread has completed its logging output and it's safe to signal
2922   // the CM thread, the flag's value in the policy has been reset.
2923   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2924 
2925   // Inner scope for scope based logging, timers, and stats collection
2926   {
2927     EvacuationInfo evacuation_info;
2928 
2929     if (collector_state()->during_initial_mark_pause()) {
2930       // We are about to start a marking cycle, so we increment the
2931       // full collection counter.
2932       increment_old_marking_cycles_started();
2933       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2934     }
2935 
2936     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2937 
2938     GCTraceCPUTime tcpu;
2939 
2940     FormatBuffer<> gc_string("Pause ");
2941     if (collector_state()->during_initial_mark_pause()) {
2942       gc_string.append("Initial Mark");
2943     } else if (collector_state()->gcs_are_young()) {
2944       gc_string.append("Young");
2945     } else {
2946       gc_string.append("Mixed");
2947     }
2948     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2949 
2950     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2951                                                                   workers()->active_workers(),
2952                                                                   Threads::number_of_non_daemon_threads());
2953     workers()->update_active_workers(active_workers);
2954     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2955 
2956     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2957     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2958 
2959     // If the secondary_free_list is not empty, append it to the
2960     // free_list. No need to wait for the cleanup operation to finish;
2961     // the region allocation code will check the secondary_free_list
2962     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2963     // set, skip this step so that the region allocation code has to
2964     // get entries from the secondary_free_list.
2965     if (!G1StressConcRegionFreeing) {
2966       append_secondary_free_list_if_not_empty_with_lock();
2967     }
2968 
2969     G1HeapTransition heap_transition(this);
2970     size_t heap_used_bytes_before_gc = used();
2971 
2972     // Don't dynamically change the number of GC threads this early.  A value of
2973     // 0 is used to indicate serial work.  When parallel work is done,
2974     // it will be set.
2975 
2976     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2977       IsGCActiveMark x;
2978 
2979       gc_prologue(false);
2980 
2981       if (VerifyRememberedSets) {
2982         log_info(gc, verify)("[Verifying RemSets before GC]");
2983         VerifyRegionRemSetClosure v_cl;
2984         heap_region_iterate(&v_cl);
2985       }
2986 
2987       _verifier->verify_before_gc();
2988 
2989       _verifier->check_bitmaps("GC Start");
2990 
2991 #if COMPILER2_OR_JVMCI
2992       DerivedPointerTable::clear();
2993 #endif
2994 
2995       // Please see comment in g1CollectedHeap.hpp and
2996       // G1CollectedHeap::ref_processing_init() to see how
2997       // reference processing currently works in G1.
2998 
2999       // Enable discovery in the STW reference processor
3000       if (g1_policy()->should_process_references()) {
3001         ref_processor_stw()->enable_discovery();
3002       } else {
3003         ref_processor_stw()->disable_discovery();
3004       }
3005 
3006       {
3007         // We want to temporarily turn off discovery by the
3008         // CM ref processor, if necessary, and turn it back on
3009         // on again later if we do. Using a scoped
3010         // NoRefDiscovery object will do this.
3011         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3012 
3013         // Forget the current alloc region (we might even choose it to be part
3014         // of the collection set!).
3015         _allocator->release_mutator_alloc_region();
3016 
3017         // This timing is only used by the ergonomics to handle our pause target.
3018         // It is unclear why this should not include the full pause. We will
3019         // investigate this in CR 7178365.
3020         //
3021         // Preserving the old comment here if that helps the investigation:
3022         //
3023         // The elapsed time induced by the start time below deliberately elides
3024         // the possible verification above.
3025         double sample_start_time_sec = os::elapsedTime();
3026 
3027         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3028 
3029         if (collector_state()->during_initial_mark_pause()) {
3030           concurrent_mark()->checkpoint_roots_initial_pre();
3031         }
3032 
3033         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3034 
3035         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3036 
3037         // Make sure the remembered sets are up to date. This needs to be
3038         // done before register_humongous_regions_with_cset(), because the
3039         // remembered sets are used there to choose eager reclaim candidates.
3040         // If the remembered sets are not up to date we might miss some
3041         // entries that need to be handled.
3042         g1_rem_set()->cleanupHRRS();
3043 
3044         register_humongous_regions_with_cset();
3045 
3046         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3047 
3048         // We call this after finalize_cset() to
3049         // ensure that the CSet has been finalized.
3050         _cm->verify_no_cset_oops();
3051 
3052         if (_hr_printer.is_active()) {
3053           G1PrintCollectionSetClosure cl(&_hr_printer);
3054           _collection_set.iterate(&cl);
3055         }
3056 
3057         // Initialize the GC alloc regions.
3058         _allocator->init_gc_alloc_regions(evacuation_info);
3059 
3060         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3061         pre_evacuate_collection_set();
3062 
3063         // Actually do the work...
3064         evacuate_collection_set(evacuation_info, &per_thread_states);
3065 
3066         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3067 
3068         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3069         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3070 
3071         eagerly_reclaim_humongous_regions();
3072 
3073         record_obj_copy_mem_stats();
3074         _survivor_evac_stats.adjust_desired_plab_sz();
3075         _old_evac_stats.adjust_desired_plab_sz();
3076 
3077         double start = os::elapsedTime();
3078         start_new_collection_set();
3079         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3080 
3081         if (evacuation_failed()) {
3082           set_used(recalculate_used());
3083           if (_archive_allocator != NULL) {
3084             _archive_allocator->clear_used();
3085           }
3086           for (uint i = 0; i < ParallelGCThreads; i++) {
3087             if (_evacuation_failed_info_array[i].has_failed()) {
3088               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3089             }
3090           }
3091         } else {
3092           // The "used" of the the collection set have already been subtracted
3093           // when they were freed.  Add in the bytes evacuated.
3094           increase_used(g1_policy()->bytes_copied_during_gc());
3095         }
3096 
3097         if (collector_state()->during_initial_mark_pause()) {
3098           // We have to do this before we notify the CM threads that
3099           // they can start working to make sure that all the
3100           // appropriate initialization is done on the CM object.
3101           concurrent_mark()->checkpoint_roots_initial_post();
3102           collector_state()->set_mark_in_progress(true);
3103           // Note that we don't actually trigger the CM thread at
3104           // this point. We do that later when we're sure that
3105           // the current thread has completed its logging output.
3106         }
3107 
3108         allocate_dummy_regions();
3109 
3110         _allocator->init_mutator_alloc_region();
3111 
3112         {
3113           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3114           if (expand_bytes > 0) {
3115             size_t bytes_before = capacity();
3116             // No need for an ergo logging here,
3117             // expansion_amount() does this when it returns a value > 0.
3118             double expand_ms;
3119             if (!expand(expand_bytes, _workers, &expand_ms)) {
3120               // We failed to expand the heap. Cannot do anything about it.
3121             }
3122             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3123           }
3124         }
3125 
3126         // We redo the verification but now wrt to the new CSet which
3127         // has just got initialized after the previous CSet was freed.
3128         _cm->verify_no_cset_oops();
3129 
3130         // This timing is only used by the ergonomics to handle our pause target.
3131         // It is unclear why this should not include the full pause. We will
3132         // investigate this in CR 7178365.
3133         double sample_end_time_sec = os::elapsedTime();
3134         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3135         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3136         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3137 
3138         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3139         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3140 
3141         if (VerifyRememberedSets) {
3142           log_info(gc, verify)("[Verifying RemSets after GC]");
3143           VerifyRegionRemSetClosure v_cl;
3144           heap_region_iterate(&v_cl);
3145         }
3146 
3147         _verifier->verify_after_gc();
3148         _verifier->check_bitmaps("GC End");
3149 
3150         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3151         ref_processor_stw()->verify_no_references_recorded();
3152 
3153         // CM reference discovery will be re-enabled if necessary.
3154       }
3155 
3156 #ifdef TRACESPINNING
3157       ParallelTaskTerminator::print_termination_counts();
3158 #endif
3159 
3160       gc_epilogue(false);
3161     }
3162 
3163     // Print the remainder of the GC log output.
3164     if (evacuation_failed()) {
3165       log_info(gc)("To-space exhausted");
3166     }
3167 
3168     g1_policy()->print_phases();
3169     heap_transition.print();
3170 
3171     // It is not yet to safe to tell the concurrent mark to
3172     // start as we have some optional output below. We don't want the
3173     // output from the concurrent mark thread interfering with this
3174     // logging output either.
3175 
3176     _hrm.verify_optional();
3177     _verifier->verify_region_sets_optional();
3178 
3179     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3180     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3181 
3182     print_heap_after_gc();
3183     print_heap_regions();
3184     trace_heap_after_gc(_gc_tracer_stw);
3185 
3186     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3187     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3188     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3189     // before any GC notifications are raised.
3190     g1mm()->update_sizes();
3191 
3192     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3193     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3194     _gc_timer_stw->register_gc_end();
3195     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3196   }
3197   // It should now be safe to tell the concurrent mark thread to start
3198   // without its logging output interfering with the logging output
3199   // that came from the pause.
3200 
3201   if (should_start_conc_mark) {
3202     // CAUTION: after the doConcurrentMark() call below,
3203     // the concurrent marking thread(s) could be running
3204     // concurrently with us. Make sure that anything after
3205     // this point does not assume that we are the only GC thread
3206     // running. Note: of course, the actual marking work will
3207     // not start until the safepoint itself is released in
3208     // SuspendibleThreadSet::desynchronize().
3209     doConcurrentMark();
3210   }
3211 
3212   return true;
3213 }
3214 
3215 void G1CollectedHeap::remove_self_forwarding_pointers() {
3216   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3217   workers()->run_task(&rsfp_task);
3218 }
3219 
3220 void G1CollectedHeap::restore_after_evac_failure() {
3221   double remove_self_forwards_start = os::elapsedTime();
3222 
3223   remove_self_forwarding_pointers();
3224   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3225   _preserved_marks_set.restore(&task_executor);
3226 
3227   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3228 }
3229 
3230 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3231   if (!_evacuation_failed) {
3232     _evacuation_failed = true;
3233   }
3234 
3235   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3236   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3237 }
3238 
3239 bool G1ParEvacuateFollowersClosure::offer_termination() {
3240   G1ParScanThreadState* const pss = par_scan_state();
3241   start_term_time();
3242   const bool res = terminator()->offer_termination();
3243   end_term_time();
3244   return res;
3245 }
3246 
3247 void G1ParEvacuateFollowersClosure::do_void() {
3248   G1ParScanThreadState* const pss = par_scan_state();
3249   pss->trim_queue();
3250   do {
3251     pss->steal_and_trim_queue(queues());
3252   } while (!offer_termination());
3253 }
3254 
3255 class G1ParTask : public AbstractGangTask {
3256 protected:
3257   G1CollectedHeap*         _g1h;
3258   G1ParScanThreadStateSet* _pss;
3259   RefToScanQueueSet*       _queues;
3260   G1RootProcessor*         _root_processor;
3261   ParallelTaskTerminator   _terminator;
3262   uint                     _n_workers;
3263 
3264 public:
3265   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3266     : AbstractGangTask("G1 collection"),
3267       _g1h(g1h),
3268       _pss(per_thread_states),
3269       _queues(task_queues),
3270       _root_processor(root_processor),
3271       _terminator(n_workers, _queues),
3272       _n_workers(n_workers)
3273   {}
3274 
3275   void work(uint worker_id) {
3276     if (worker_id >= _n_workers) return;  // no work needed this round
3277 
3278     double start_sec = os::elapsedTime();
3279     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3280 
3281     {
3282       ResourceMark rm;
3283       HandleMark   hm;
3284 
3285       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3286 
3287       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3288       pss->set_ref_processor(rp);
3289 
3290       double start_strong_roots_sec = os::elapsedTime();
3291 
3292       _root_processor->evacuate_roots(pss->closures(), worker_id);
3293 
3294       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3295       // treating the nmethods visited to act as roots for concurrent marking.
3296       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3297       // objects copied by the current evacuation.
3298       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3299                                                       pss->closures()->weak_codeblobs(),
3300                                                       worker_id);
3301 
3302       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3303 
3304       double term_sec = 0.0;
3305       size_t evac_term_attempts = 0;
3306       {
3307         double start = os::elapsedTime();
3308         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3309         evac.do_void();
3310 
3311         evac_term_attempts = evac.term_attempts();
3312         term_sec = evac.term_time();
3313         double elapsed_sec = os::elapsedTime() - start;
3314         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3315         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3316         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3317       }
3318 
3319       assert(pss->queue_is_empty(), "should be empty");
3320 
3321       if (log_is_enabled(Debug, gc, task, stats)) {
3322         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3323         size_t lab_waste;
3324         size_t lab_undo_waste;
3325         pss->waste(lab_waste, lab_undo_waste);
3326         _g1h->print_termination_stats(worker_id,
3327                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3328                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3329                                       term_sec * 1000.0,                          /* evac term time */
3330                                       evac_term_attempts,                         /* evac term attempts */
3331                                       lab_waste,                                  /* alloc buffer waste */
3332                                       lab_undo_waste                              /* undo waste */
3333                                       );
3334       }
3335 
3336       // Close the inner scope so that the ResourceMark and HandleMark
3337       // destructors are executed here and are included as part of the
3338       // "GC Worker Time".
3339     }
3340     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3341   }
3342 };
3343 
3344 void G1CollectedHeap::print_termination_stats_hdr() {
3345   log_debug(gc, task, stats)("GC Termination Stats");
3346   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3347   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3348   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3349 }
3350 
3351 void G1CollectedHeap::print_termination_stats(uint worker_id,
3352                                               double elapsed_ms,
3353                                               double strong_roots_ms,
3354                                               double term_ms,
3355                                               size_t term_attempts,
3356                                               size_t alloc_buffer_waste,
3357                                               size_t undo_waste) const {
3358   log_debug(gc, task, stats)
3359               ("%3d %9.2f %9.2f %6.2f "
3360                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3361                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3362                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3363                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3364                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3365                alloc_buffer_waste * HeapWordSize / K,
3366                undo_waste * HeapWordSize / K);
3367 }
3368 
3369 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3370 private:
3371   BoolObjectClosure* _is_alive;
3372   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3373 
3374   int _initial_string_table_size;
3375   int _initial_symbol_table_size;
3376 
3377   bool  _process_strings;
3378   int _strings_processed;
3379   int _strings_removed;
3380 
3381   bool  _process_symbols;
3382   int _symbols_processed;
3383   int _symbols_removed;
3384 
3385   bool _process_string_dedup;
3386 
3387 public:
3388   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3389     AbstractGangTask("String/Symbol Unlinking"),
3390     _is_alive(is_alive),
3391     _dedup_closure(is_alive, NULL, false),
3392     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3393     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3394     _process_string_dedup(process_string_dedup) {
3395 
3396     _initial_string_table_size = StringTable::the_table()->table_size();
3397     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3398     if (process_strings) {
3399       StringTable::clear_parallel_claimed_index();
3400     }
3401     if (process_symbols) {
3402       SymbolTable::clear_parallel_claimed_index();
3403     }
3404   }
3405 
3406   ~G1StringAndSymbolCleaningTask() {
3407     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3408               "claim value %d after unlink less than initial string table size %d",
3409               StringTable::parallel_claimed_index(), _initial_string_table_size);
3410     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3411               "claim value %d after unlink less than initial symbol table size %d",
3412               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3413 
3414     log_info(gc, stringtable)(
3415         "Cleaned string and symbol table, "
3416         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3417         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3418         strings_processed(), strings_removed(),
3419         symbols_processed(), symbols_removed());
3420   }
3421 
3422   void work(uint worker_id) {
3423     int strings_processed = 0;
3424     int strings_removed = 0;
3425     int symbols_processed = 0;
3426     int symbols_removed = 0;
3427     if (_process_strings) {
3428       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3429       Atomic::add(strings_processed, &_strings_processed);
3430       Atomic::add(strings_removed, &_strings_removed);
3431     }
3432     if (_process_symbols) {
3433       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3434       Atomic::add(symbols_processed, &_symbols_processed);
3435       Atomic::add(symbols_removed, &_symbols_removed);
3436     }
3437     if (_process_string_dedup) {
3438       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3439     }
3440   }
3441 
3442   size_t strings_processed() const { return (size_t)_strings_processed; }
3443   size_t strings_removed()   const { return (size_t)_strings_removed; }
3444 
3445   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3446   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3447 };
3448 
3449 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3450 private:
3451   static Monitor* _lock;
3452 
3453   BoolObjectClosure* const _is_alive;
3454   const bool               _unloading_occurred;
3455   const uint               _num_workers;
3456 
3457   // Variables used to claim nmethods.
3458   CompiledMethod* _first_nmethod;
3459   CompiledMethod* volatile _claimed_nmethod;
3460 
3461   // The list of nmethods that need to be processed by the second pass.
3462   CompiledMethod* volatile _postponed_list;
3463   volatile uint            _num_entered_barrier;
3464 
3465  public:
3466   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3467       _is_alive(is_alive),
3468       _unloading_occurred(unloading_occurred),
3469       _num_workers(num_workers),
3470       _first_nmethod(NULL),
3471       _claimed_nmethod(NULL),
3472       _postponed_list(NULL),
3473       _num_entered_barrier(0)
3474   {
3475     CompiledMethod::increase_unloading_clock();
3476     // Get first alive nmethod
3477     CompiledMethodIterator iter = CompiledMethodIterator();
3478     if(iter.next_alive()) {
3479       _first_nmethod = iter.method();
3480     }
3481     _claimed_nmethod = _first_nmethod;
3482   }
3483 
3484   ~G1CodeCacheUnloadingTask() {
3485     CodeCache::verify_clean_inline_caches();
3486 
3487     CodeCache::set_needs_cache_clean(false);
3488     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3489 
3490     CodeCache::verify_icholder_relocations();
3491   }
3492 
3493  private:
3494   void add_to_postponed_list(CompiledMethod* nm) {
3495       CompiledMethod* old;
3496       do {
3497         old = _postponed_list;
3498         nm->set_unloading_next(old);
3499       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3500   }
3501 
3502   void clean_nmethod(CompiledMethod* nm) {
3503     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3504 
3505     if (postponed) {
3506       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3507       add_to_postponed_list(nm);
3508     }
3509 
3510     // Mark that this thread has been cleaned/unloaded.
3511     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3512     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3513   }
3514 
3515   void clean_nmethod_postponed(CompiledMethod* nm) {
3516     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3517   }
3518 
3519   static const int MaxClaimNmethods = 16;
3520 
3521   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3522     CompiledMethod* first;
3523     CompiledMethodIterator last;
3524 
3525     do {
3526       *num_claimed_nmethods = 0;
3527 
3528       first = _claimed_nmethod;
3529       last = CompiledMethodIterator(first);
3530 
3531       if (first != NULL) {
3532 
3533         for (int i = 0; i < MaxClaimNmethods; i++) {
3534           if (!last.next_alive()) {
3535             break;
3536           }
3537           claimed_nmethods[i] = last.method();
3538           (*num_claimed_nmethods)++;
3539         }
3540       }
3541 
3542     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3543   }
3544 
3545   CompiledMethod* claim_postponed_nmethod() {
3546     CompiledMethod* claim;
3547     CompiledMethod* next;
3548 
3549     do {
3550       claim = _postponed_list;
3551       if (claim == NULL) {
3552         return NULL;
3553       }
3554 
3555       next = claim->unloading_next();
3556 
3557     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3558 
3559     return claim;
3560   }
3561 
3562  public:
3563   // Mark that we're done with the first pass of nmethod cleaning.
3564   void barrier_mark(uint worker_id) {
3565     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3566     _num_entered_barrier++;
3567     if (_num_entered_barrier == _num_workers) {
3568       ml.notify_all();
3569     }
3570   }
3571 
3572   // See if we have to wait for the other workers to
3573   // finish their first-pass nmethod cleaning work.
3574   void barrier_wait(uint worker_id) {
3575     if (_num_entered_barrier < _num_workers) {
3576       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3577       while (_num_entered_barrier < _num_workers) {
3578           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3579       }
3580     }
3581   }
3582 
3583   // Cleaning and unloading of nmethods. Some work has to be postponed
3584   // to the second pass, when we know which nmethods survive.
3585   void work_first_pass(uint worker_id) {
3586     // The first nmethods is claimed by the first worker.
3587     if (worker_id == 0 && _first_nmethod != NULL) {
3588       clean_nmethod(_first_nmethod);
3589       _first_nmethod = NULL;
3590     }
3591 
3592     int num_claimed_nmethods;
3593     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3594 
3595     while (true) {
3596       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3597 
3598       if (num_claimed_nmethods == 0) {
3599         break;
3600       }
3601 
3602       for (int i = 0; i < num_claimed_nmethods; i++) {
3603         clean_nmethod(claimed_nmethods[i]);
3604       }
3605     }
3606   }
3607 
3608   void work_second_pass(uint worker_id) {
3609     CompiledMethod* nm;
3610     // Take care of postponed nmethods.
3611     while ((nm = claim_postponed_nmethod()) != NULL) {
3612       clean_nmethod_postponed(nm);
3613     }
3614   }
3615 };
3616 
3617 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3618 
3619 class G1KlassCleaningTask : public StackObj {
3620   BoolObjectClosure*                      _is_alive;
3621   volatile int                            _clean_klass_tree_claimed;
3622   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3623 
3624  public:
3625   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3626       _is_alive(is_alive),
3627       _clean_klass_tree_claimed(0),
3628       _klass_iterator() {
3629   }
3630 
3631  private:
3632   bool claim_clean_klass_tree_task() {
3633     if (_clean_klass_tree_claimed) {
3634       return false;
3635     }
3636 
3637     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3638   }
3639 
3640   InstanceKlass* claim_next_klass() {
3641     Klass* klass;
3642     do {
3643       klass =_klass_iterator.next_klass();
3644     } while (klass != NULL && !klass->is_instance_klass());
3645 
3646     // this can be null so don't call InstanceKlass::cast
3647     return static_cast<InstanceKlass*>(klass);
3648   }
3649 
3650 public:
3651 
3652   void clean_klass(InstanceKlass* ik) {
3653     ik->clean_weak_instanceklass_links(_is_alive);
3654   }
3655 
3656   void work() {
3657     ResourceMark rm;
3658 
3659     // One worker will clean the subklass/sibling klass tree.
3660     if (claim_clean_klass_tree_task()) {
3661       Klass::clean_subklass_tree(_is_alive);
3662     }
3663 
3664     // All workers will help cleaning the classes,
3665     InstanceKlass* klass;
3666     while ((klass = claim_next_klass()) != NULL) {
3667       clean_klass(klass);
3668     }
3669   }
3670 };
3671 
3672 class G1ResolvedMethodCleaningTask : public StackObj {
3673   BoolObjectClosure* _is_alive;
3674   volatile int       _resolved_method_task_claimed;
3675 public:
3676   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3677       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3678 
3679   bool claim_resolved_method_task() {
3680     if (_resolved_method_task_claimed) {
3681       return false;
3682     }
3683     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3684   }
3685 
3686   // These aren't big, one thread can do it all.
3687   void work() {
3688     if (claim_resolved_method_task()) {
3689       ResolvedMethodTable::unlink(_is_alive);
3690     }
3691   }
3692 };
3693 
3694 
3695 // To minimize the remark pause times, the tasks below are done in parallel.
3696 class G1ParallelCleaningTask : public AbstractGangTask {
3697 private:
3698   G1StringAndSymbolCleaningTask _string_symbol_task;
3699   G1CodeCacheUnloadingTask      _code_cache_task;
3700   G1KlassCleaningTask           _klass_cleaning_task;
3701   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3702 
3703 public:
3704   // The constructor is run in the VMThread.
3705   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3706       AbstractGangTask("Parallel Cleaning"),
3707       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3708       _code_cache_task(num_workers, is_alive, unloading_occurred),
3709       _klass_cleaning_task(is_alive),
3710       _resolved_method_cleaning_task(is_alive) {
3711   }
3712 
3713   // The parallel work done by all worker threads.
3714   void work(uint worker_id) {
3715     // Do first pass of code cache cleaning.
3716     _code_cache_task.work_first_pass(worker_id);
3717 
3718     // Let the threads mark that the first pass is done.
3719     _code_cache_task.barrier_mark(worker_id);
3720 
3721     // Clean the Strings and Symbols.
3722     _string_symbol_task.work(worker_id);
3723 
3724     // Clean unreferenced things in the ResolvedMethodTable
3725     _resolved_method_cleaning_task.work();
3726 
3727     // Wait for all workers to finish the first code cache cleaning pass.
3728     _code_cache_task.barrier_wait(worker_id);
3729 
3730     // Do the second code cache cleaning work, which realize on
3731     // the liveness information gathered during the first pass.
3732     _code_cache_task.work_second_pass(worker_id);
3733 
3734     // Clean all klasses that were not unloaded.
3735     _klass_cleaning_task.work();
3736   }
3737 };
3738 
3739 
3740 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3741                                         bool class_unloading_occurred) {
3742   uint n_workers = workers()->active_workers();
3743 
3744   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3745   workers()->run_task(&g1_unlink_task);
3746 }
3747 
3748 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3749                                        bool process_strings,
3750                                        bool process_symbols,
3751                                        bool process_string_dedup) {
3752   if (!process_strings && !process_symbols && !process_string_dedup) {
3753     // Nothing to clean.
3754     return;
3755   }
3756 
3757   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3758   workers()->run_task(&g1_unlink_task);
3759 
3760 }
3761 
3762 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3763  private:
3764   DirtyCardQueueSet* _queue;
3765   G1CollectedHeap* _g1h;
3766  public:
3767   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3768     _queue(queue), _g1h(g1h) { }
3769 
3770   virtual void work(uint worker_id) {
3771     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3772     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3773 
3774     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3775     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3776 
3777     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3778   }
3779 };
3780 
3781 void G1CollectedHeap::redirty_logged_cards() {
3782   double redirty_logged_cards_start = os::elapsedTime();
3783 
3784   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3785   dirty_card_queue_set().reset_for_par_iteration();
3786   workers()->run_task(&redirty_task);
3787 
3788   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3789   dcq.merge_bufferlists(&dirty_card_queue_set());
3790   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3791 
3792   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3793 }
3794 
3795 // Weak Reference Processing support
3796 
3797 // An always "is_alive" closure that is used to preserve referents.
3798 // If the object is non-null then it's alive.  Used in the preservation
3799 // of referent objects that are pointed to by reference objects
3800 // discovered by the CM ref processor.
3801 class G1AlwaysAliveClosure: public BoolObjectClosure {
3802   G1CollectedHeap* _g1;
3803 public:
3804   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3805   bool do_object_b(oop p) {
3806     if (p != NULL) {
3807       return true;
3808     }
3809     return false;
3810   }
3811 };
3812 
3813 bool G1STWIsAliveClosure::do_object_b(oop p) {
3814   // An object is reachable if it is outside the collection set,
3815   // or is inside and copied.
3816   return !_g1->is_in_cset(p) || p->is_forwarded();
3817 }
3818 
3819 // Non Copying Keep Alive closure
3820 class G1KeepAliveClosure: public OopClosure {
3821   G1CollectedHeap* _g1;
3822 public:
3823   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3824   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3825   void do_oop(oop* p) {
3826     oop obj = *p;
3827     assert(obj != NULL, "the caller should have filtered out NULL values");
3828 
3829     const InCSetState cset_state = _g1->in_cset_state(obj);
3830     if (!cset_state.is_in_cset_or_humongous()) {
3831       return;
3832     }
3833     if (cset_state.is_in_cset()) {
3834       assert( obj->is_forwarded(), "invariant" );
3835       *p = obj->forwardee();
3836     } else {
3837       assert(!obj->is_forwarded(), "invariant" );
3838       assert(cset_state.is_humongous(),
3839              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3840       _g1->set_humongous_is_live(obj);
3841     }
3842   }
3843 };
3844 
3845 // Copying Keep Alive closure - can be called from both
3846 // serial and parallel code as long as different worker
3847 // threads utilize different G1ParScanThreadState instances
3848 // and different queues.
3849 
3850 class G1CopyingKeepAliveClosure: public OopClosure {
3851   G1CollectedHeap*         _g1h;
3852   OopClosure*              _copy_non_heap_obj_cl;
3853   G1ParScanThreadState*    _par_scan_state;
3854 
3855 public:
3856   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3857                             OopClosure* non_heap_obj_cl,
3858                             G1ParScanThreadState* pss):
3859     _g1h(g1h),
3860     _copy_non_heap_obj_cl(non_heap_obj_cl),
3861     _par_scan_state(pss)
3862   {}
3863 
3864   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3865   virtual void do_oop(      oop* p) { do_oop_work(p); }
3866 
3867   template <class T> void do_oop_work(T* p) {
3868     oop obj = oopDesc::load_decode_heap_oop(p);
3869 
3870     if (_g1h->is_in_cset_or_humongous(obj)) {
3871       // If the referent object has been forwarded (either copied
3872       // to a new location or to itself in the event of an
3873       // evacuation failure) then we need to update the reference
3874       // field and, if both reference and referent are in the G1
3875       // heap, update the RSet for the referent.
3876       //
3877       // If the referent has not been forwarded then we have to keep
3878       // it alive by policy. Therefore we have copy the referent.
3879       //
3880       // If the reference field is in the G1 heap then we can push
3881       // on the PSS queue. When the queue is drained (after each
3882       // phase of reference processing) the object and it's followers
3883       // will be copied, the reference field set to point to the
3884       // new location, and the RSet updated. Otherwise we need to
3885       // use the the non-heap or metadata closures directly to copy
3886       // the referent object and update the pointer, while avoiding
3887       // updating the RSet.
3888 
3889       if (_g1h->is_in_g1_reserved(p)) {
3890         _par_scan_state->push_on_queue(p);
3891       } else {
3892         assert(!Metaspace::contains((const void*)p),
3893                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3894         _copy_non_heap_obj_cl->do_oop(p);
3895       }
3896     }
3897   }
3898 };
3899 
3900 // Serial drain queue closure. Called as the 'complete_gc'
3901 // closure for each discovered list in some of the
3902 // reference processing phases.
3903 
3904 class G1STWDrainQueueClosure: public VoidClosure {
3905 protected:
3906   G1CollectedHeap* _g1h;
3907   G1ParScanThreadState* _par_scan_state;
3908 
3909   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3910 
3911 public:
3912   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3913     _g1h(g1h),
3914     _par_scan_state(pss)
3915   { }
3916 
3917   void do_void() {
3918     G1ParScanThreadState* const pss = par_scan_state();
3919     pss->trim_queue();
3920   }
3921 };
3922 
3923 // Parallel Reference Processing closures
3924 
3925 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3926 // processing during G1 evacuation pauses.
3927 
3928 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3929 private:
3930   G1CollectedHeap*          _g1h;
3931   G1ParScanThreadStateSet*  _pss;
3932   RefToScanQueueSet*        _queues;
3933   WorkGang*                 _workers;
3934   uint                      _active_workers;
3935 
3936 public:
3937   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3938                            G1ParScanThreadStateSet* per_thread_states,
3939                            WorkGang* workers,
3940                            RefToScanQueueSet *task_queues,
3941                            uint n_workers) :
3942     _g1h(g1h),
3943     _pss(per_thread_states),
3944     _queues(task_queues),
3945     _workers(workers),
3946     _active_workers(n_workers)
3947   {
3948     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3949   }
3950 
3951   // Executes the given task using concurrent marking worker threads.
3952   virtual void execute(ProcessTask& task);
3953   virtual void execute(EnqueueTask& task);
3954 };
3955 
3956 // Gang task for possibly parallel reference processing
3957 
3958 class G1STWRefProcTaskProxy: public AbstractGangTask {
3959   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3960   ProcessTask&     _proc_task;
3961   G1CollectedHeap* _g1h;
3962   G1ParScanThreadStateSet* _pss;
3963   RefToScanQueueSet* _task_queues;
3964   ParallelTaskTerminator* _terminator;
3965 
3966 public:
3967   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3968                         G1CollectedHeap* g1h,
3969                         G1ParScanThreadStateSet* per_thread_states,
3970                         RefToScanQueueSet *task_queues,
3971                         ParallelTaskTerminator* terminator) :
3972     AbstractGangTask("Process reference objects in parallel"),
3973     _proc_task(proc_task),
3974     _g1h(g1h),
3975     _pss(per_thread_states),
3976     _task_queues(task_queues),
3977     _terminator(terminator)
3978   {}
3979 
3980   virtual void work(uint worker_id) {
3981     // The reference processing task executed by a single worker.
3982     ResourceMark rm;
3983     HandleMark   hm;
3984 
3985     G1STWIsAliveClosure is_alive(_g1h);
3986 
3987     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3988     pss->set_ref_processor(NULL);
3989 
3990     // Keep alive closure.
3991     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3992 
3993     // Complete GC closure
3994     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3995 
3996     // Call the reference processing task's work routine.
3997     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3998 
3999     // Note we cannot assert that the refs array is empty here as not all
4000     // of the processing tasks (specifically phase2 - pp2_work) execute
4001     // the complete_gc closure (which ordinarily would drain the queue) so
4002     // the queue may not be empty.
4003   }
4004 };
4005 
4006 // Driver routine for parallel reference processing.
4007 // Creates an instance of the ref processing gang
4008 // task and has the worker threads execute it.
4009 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4010   assert(_workers != NULL, "Need parallel worker threads.");
4011 
4012   ParallelTaskTerminator terminator(_active_workers, _queues);
4013   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4014 
4015   _workers->run_task(&proc_task_proxy);
4016 }
4017 
4018 // Gang task for parallel reference enqueueing.
4019 
4020 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4021   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4022   EnqueueTask& _enq_task;
4023 
4024 public:
4025   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4026     AbstractGangTask("Enqueue reference objects in parallel"),
4027     _enq_task(enq_task)
4028   { }
4029 
4030   virtual void work(uint worker_id) {
4031     _enq_task.work(worker_id);
4032   }
4033 };
4034 
4035 // Driver routine for parallel reference enqueueing.
4036 // Creates an instance of the ref enqueueing gang
4037 // task and has the worker threads execute it.
4038 
4039 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4040   assert(_workers != NULL, "Need parallel worker threads.");
4041 
4042   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4043 
4044   _workers->run_task(&enq_task_proxy);
4045 }
4046 
4047 // End of weak reference support closures
4048 
4049 // Abstract task used to preserve (i.e. copy) any referent objects
4050 // that are in the collection set and are pointed to by reference
4051 // objects discovered by the CM ref processor.
4052 
4053 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4054 protected:
4055   G1CollectedHeap*         _g1h;
4056   G1ParScanThreadStateSet* _pss;
4057   RefToScanQueueSet*       _queues;
4058   ParallelTaskTerminator   _terminator;
4059   uint                     _n_workers;
4060 
4061 public:
4062   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4063     AbstractGangTask("ParPreserveCMReferents"),
4064     _g1h(g1h),
4065     _pss(per_thread_states),
4066     _queues(task_queues),
4067     _terminator(workers, _queues),
4068     _n_workers(workers)
4069   {
4070     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4071   }
4072 
4073   void work(uint worker_id) {
4074     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4075 
4076     ResourceMark rm;
4077     HandleMark   hm;
4078 
4079     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4080     pss->set_ref_processor(NULL);
4081     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4082 
4083     // Is alive closure
4084     G1AlwaysAliveClosure always_alive(_g1h);
4085 
4086     // Copying keep alive closure. Applied to referent objects that need
4087     // to be copied.
4088     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4089 
4090     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4091 
4092     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4093     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4094 
4095     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4096     // So this must be true - but assert just in case someone decides to
4097     // change the worker ids.
4098     assert(worker_id < limit, "sanity");
4099     assert(!rp->discovery_is_atomic(), "check this code");
4100 
4101     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4102     for (uint idx = worker_id; idx < limit; idx += stride) {
4103       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4104 
4105       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4106       while (iter.has_next()) {
4107         // Since discovery is not atomic for the CM ref processor, we
4108         // can see some null referent objects.
4109         iter.load_ptrs(DEBUG_ONLY(true));
4110         oop ref = iter.obj();
4111 
4112         // This will filter nulls.
4113         if (iter.is_referent_alive()) {
4114           iter.make_referent_alive();
4115         }
4116         iter.move_to_next();
4117       }
4118     }
4119 
4120     // Drain the queue - which may cause stealing
4121     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4122     drain_queue.do_void();
4123     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4124     assert(pss->queue_is_empty(), "should be");
4125   }
4126 };
4127 
4128 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4129   // Any reference objects, in the collection set, that were 'discovered'
4130   // by the CM ref processor should have already been copied (either by
4131   // applying the external root copy closure to the discovered lists, or
4132   // by following an RSet entry).
4133   //
4134   // But some of the referents, that are in the collection set, that these
4135   // reference objects point to may not have been copied: the STW ref
4136   // processor would have seen that the reference object had already
4137   // been 'discovered' and would have skipped discovering the reference,
4138   // but would not have treated the reference object as a regular oop.
4139   // As a result the copy closure would not have been applied to the
4140   // referent object.
4141   //
4142   // We need to explicitly copy these referent objects - the references
4143   // will be processed at the end of remarking.
4144   //
4145   // We also need to do this copying before we process the reference
4146   // objects discovered by the STW ref processor in case one of these
4147   // referents points to another object which is also referenced by an
4148   // object discovered by the STW ref processor.
4149   double preserve_cm_referents_time = 0.0;
4150 
4151   // To avoid spawning task when there is no work to do, check that
4152   // a concurrent cycle is active and that some references have been
4153   // discovered.
4154   if (concurrent_mark()->cm_thread()->during_cycle() &&
4155       ref_processor_cm()->has_discovered_references()) {
4156     double preserve_cm_referents_start = os::elapsedTime();
4157     uint no_of_gc_workers = workers()->active_workers();
4158     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4159                                                    per_thread_states,
4160                                                    no_of_gc_workers,
4161                                                    _task_queues);
4162     workers()->run_task(&keep_cm_referents);
4163     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4164   }
4165 
4166   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4167 }
4168 
4169 // Weak Reference processing during an evacuation pause (part 1).
4170 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4171   double ref_proc_start = os::elapsedTime();
4172 
4173   ReferenceProcessor* rp = _ref_processor_stw;
4174   assert(rp->discovery_enabled(), "should have been enabled");
4175 
4176   // Closure to test whether a referent is alive.
4177   G1STWIsAliveClosure is_alive(this);
4178 
4179   // Even when parallel reference processing is enabled, the processing
4180   // of JNI refs is serial and performed serially by the current thread
4181   // rather than by a worker. The following PSS will be used for processing
4182   // JNI refs.
4183 
4184   // Use only a single queue for this PSS.
4185   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4186   pss->set_ref_processor(NULL);
4187   assert(pss->queue_is_empty(), "pre-condition");
4188 
4189   // Keep alive closure.
4190   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4191 
4192   // Serial Complete GC closure
4193   G1STWDrainQueueClosure drain_queue(this, pss);
4194 
4195   // Setup the soft refs policy...
4196   rp->setup_policy(false);
4197 
4198   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4199 
4200   ReferenceProcessorStats stats;
4201   if (!rp->processing_is_mt()) {
4202     // Serial reference processing...
4203     stats = rp->process_discovered_references(&is_alive,
4204                                               &keep_alive,
4205                                               &drain_queue,
4206                                               NULL,
4207                                               pt);
4208   } else {
4209     uint no_of_gc_workers = workers()->active_workers();
4210 
4211     // Parallel reference processing
4212     assert(no_of_gc_workers <= rp->max_num_q(),
4213            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4214            no_of_gc_workers,  rp->max_num_q());
4215 
4216     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4217     stats = rp->process_discovered_references(&is_alive,
4218                                               &keep_alive,
4219                                               &drain_queue,
4220                                               &par_task_executor,
4221                                               pt);
4222   }
4223 
4224   _gc_tracer_stw->report_gc_reference_stats(stats);
4225 
4226   // We have completed copying any necessary live referent objects.
4227   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4228 
4229   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4230   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4231 }
4232 
4233 // Weak Reference processing during an evacuation pause (part 2).
4234 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4235   double ref_enq_start = os::elapsedTime();
4236 
4237   ReferenceProcessor* rp = _ref_processor_stw;
4238   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4239 
4240   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4241 
4242   // Now enqueue any remaining on the discovered lists on to
4243   // the pending list.
4244   if (!rp->processing_is_mt()) {
4245     // Serial reference processing...
4246     rp->enqueue_discovered_references(NULL, pt);
4247   } else {
4248     // Parallel reference enqueueing
4249 
4250     uint n_workers = workers()->active_workers();
4251 
4252     assert(n_workers <= rp->max_num_q(),
4253            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4254            n_workers,  rp->max_num_q());
4255 
4256     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4257     rp->enqueue_discovered_references(&par_task_executor, pt);
4258   }
4259 
4260   rp->verify_no_references_recorded();
4261   assert(!rp->discovery_enabled(), "should have been disabled");
4262 
4263   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4264   // ensure that it is marked in the bitmap for concurrent marking to discover.
4265   if (collector_state()->during_initial_mark_pause()) {
4266     oop pll_head = Universe::reference_pending_list();
4267     if (pll_head != NULL) {
4268       _cm->mark_in_next_bitmap(pll_head);
4269     }
4270   }
4271 
4272   // FIXME
4273   // CM's reference processing also cleans up the string and symbol tables.
4274   // Should we do that here also? We could, but it is a serial operation
4275   // and could significantly increase the pause time.
4276 
4277   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4278   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4279 }
4280 
4281 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4282   double merge_pss_time_start = os::elapsedTime();
4283   per_thread_states->flush();
4284   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4285 }
4286 
4287 void G1CollectedHeap::pre_evacuate_collection_set() {
4288   _expand_heap_after_alloc_failure = true;
4289   _evacuation_failed = false;
4290 
4291   // Disable the hot card cache.
4292   _hot_card_cache->reset_hot_cache_claimed_index();
4293   _hot_card_cache->set_use_cache(false);
4294 
4295   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4296   _preserved_marks_set.assert_empty();
4297 
4298   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4299 
4300   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4301   if (collector_state()->during_initial_mark_pause()) {
4302     double start_clear_claimed_marks = os::elapsedTime();
4303 
4304     ClassLoaderDataGraph::clear_claimed_marks();
4305 
4306     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4307     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4308   }
4309 }
4310 
4311 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4312   // Should G1EvacuationFailureALot be in effect for this GC?
4313   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4314 
4315   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4316 
4317   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4318 
4319   double start_par_time_sec = os::elapsedTime();
4320   double end_par_time_sec;
4321 
4322   {
4323     const uint n_workers = workers()->active_workers();
4324     G1RootProcessor root_processor(this, n_workers);
4325     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4326 
4327     print_termination_stats_hdr();
4328 
4329     workers()->run_task(&g1_par_task);
4330     end_par_time_sec = os::elapsedTime();
4331 
4332     // Closing the inner scope will execute the destructor
4333     // for the G1RootProcessor object. We record the current
4334     // elapsed time before closing the scope so that time
4335     // taken for the destructor is NOT included in the
4336     // reported parallel time.
4337   }
4338 
4339   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4340   phase_times->record_par_time(par_time_ms);
4341 
4342   double code_root_fixup_time_ms =
4343         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4344   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4345 }
4346 
4347 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4348   // Process any discovered reference objects - we have
4349   // to do this _before_ we retire the GC alloc regions
4350   // as we may have to copy some 'reachable' referent
4351   // objects (and their reachable sub-graphs) that were
4352   // not copied during the pause.
4353   if (g1_policy()->should_process_references()) {
4354     preserve_cm_referents(per_thread_states);
4355     process_discovered_references(per_thread_states);
4356   } else {
4357     ref_processor_stw()->verify_no_references_recorded();
4358   }
4359 
4360   G1STWIsAliveClosure is_alive(this);
4361   G1KeepAliveClosure keep_alive(this);
4362 
4363   {
4364     double start = os::elapsedTime();
4365 
4366     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4367 
4368     double time_ms = (os::elapsedTime() - start) * 1000.0;
4369     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4370   }
4371 
4372   if (G1StringDedup::is_enabled()) {
4373     double fixup_start = os::elapsedTime();
4374 
4375     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4376 
4377     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4378     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4379   }
4380 
4381   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4382 
4383   if (evacuation_failed()) {
4384     restore_after_evac_failure();
4385 
4386     // Reset the G1EvacuationFailureALot counters and flags
4387     // Note: the values are reset only when an actual
4388     // evacuation failure occurs.
4389     NOT_PRODUCT(reset_evacuation_should_fail();)
4390   }
4391 
4392   _preserved_marks_set.assert_empty();
4393 
4394   // Enqueue any remaining references remaining on the STW
4395   // reference processor's discovered lists. We need to do
4396   // this after the card table is cleaned (and verified) as
4397   // the act of enqueueing entries on to the pending list
4398   // will log these updates (and dirty their associated
4399   // cards). We need these updates logged to update any
4400   // RSets.
4401   if (g1_policy()->should_process_references()) {
4402     enqueue_discovered_references(per_thread_states);
4403   } else {
4404     g1_policy()->phase_times()->record_ref_enq_time(0);
4405   }
4406 
4407   _allocator->release_gc_alloc_regions(evacuation_info);
4408 
4409   merge_per_thread_state_info(per_thread_states);
4410 
4411   // Reset and re-enable the hot card cache.
4412   // Note the counts for the cards in the regions in the
4413   // collection set are reset when the collection set is freed.
4414   _hot_card_cache->reset_hot_cache();
4415   _hot_card_cache->set_use_cache(true);
4416 
4417   purge_code_root_memory();
4418 
4419   redirty_logged_cards();
4420 #if COMPILER2_OR_JVMCI
4421   double start = os::elapsedTime();
4422   DerivedPointerTable::update_pointers();
4423   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4424 #endif
4425   g1_policy()->print_age_table();
4426 }
4427 
4428 void G1CollectedHeap::record_obj_copy_mem_stats() {
4429   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4430 
4431   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4432                                                create_g1_evac_summary(&_old_evac_stats));
4433 }
4434 
4435 void G1CollectedHeap::free_region(HeapRegion* hr,
4436                                   FreeRegionList* free_list,
4437                                   bool skip_remset,
4438                                   bool skip_hot_card_cache,
4439                                   bool locked) {
4440   assert(!hr->is_free(), "the region should not be free");
4441   assert(!hr->is_empty(), "the region should not be empty");
4442   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4443   assert(free_list != NULL, "pre-condition");
4444 
4445   if (G1VerifyBitmaps) {
4446     MemRegion mr(hr->bottom(), hr->end());
4447     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4448   }
4449 
4450   // Clear the card counts for this region.
4451   // Note: we only need to do this if the region is not young
4452   // (since we don't refine cards in young regions).
4453   if (!skip_hot_card_cache && !hr->is_young()) {
4454     _hot_card_cache->reset_card_counts(hr);
4455   }
4456   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4457   free_list->add_ordered(hr);
4458 }
4459 
4460 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4461                                             FreeRegionList* free_list,
4462                                             bool skip_remset) {
4463   assert(hr->is_humongous(), "this is only for humongous regions");
4464   assert(free_list != NULL, "pre-condition");
4465   hr->clear_humongous();
4466   free_region(hr, free_list, skip_remset);
4467 }
4468 
4469 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4470                                            const uint humongous_regions_removed) {
4471   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4472     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4473     _old_set.bulk_remove(old_regions_removed);
4474     _humongous_set.bulk_remove(humongous_regions_removed);
4475   }
4476 
4477 }
4478 
4479 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4480   assert(list != NULL, "list can't be null");
4481   if (!list->is_empty()) {
4482     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4483     _hrm.insert_list_into_free_list(list);
4484   }
4485 }
4486 
4487 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4488   decrease_used(bytes);
4489 }
4490 
4491 class G1ParScrubRemSetTask: public AbstractGangTask {
4492 protected:
4493   G1RemSet* _g1rs;
4494   HeapRegionClaimer _hrclaimer;
4495 
4496 public:
4497   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4498     AbstractGangTask("G1 ScrubRS"),
4499     _g1rs(g1_rs),
4500     _hrclaimer(num_workers) {
4501   }
4502 
4503   void work(uint worker_id) {
4504     _g1rs->scrub(worker_id, &_hrclaimer);
4505   }
4506 };
4507 
4508 void G1CollectedHeap::scrub_rem_set() {
4509   uint num_workers = workers()->active_workers();
4510   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4511   workers()->run_task(&g1_par_scrub_rs_task);
4512 }
4513 
4514 class G1FreeCollectionSetTask : public AbstractGangTask {
4515 private:
4516 
4517   // Closure applied to all regions in the collection set to do work that needs to
4518   // be done serially in a single thread.
4519   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4520   private:
4521     EvacuationInfo* _evacuation_info;
4522     const size_t* _surviving_young_words;
4523 
4524     // Bytes used in successfully evacuated regions before the evacuation.
4525     size_t _before_used_bytes;
4526     // Bytes used in unsucessfully evacuated regions before the evacuation
4527     size_t _after_used_bytes;
4528 
4529     size_t _bytes_allocated_in_old_since_last_gc;
4530 
4531     size_t _failure_used_words;
4532     size_t _failure_waste_words;
4533 
4534     FreeRegionList _local_free_list;
4535   public:
4536     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4537       HeapRegionClosure(),
4538       _evacuation_info(evacuation_info),
4539       _surviving_young_words(surviving_young_words),
4540       _before_used_bytes(0),
4541       _after_used_bytes(0),
4542       _bytes_allocated_in_old_since_last_gc(0),
4543       _failure_used_words(0),
4544       _failure_waste_words(0),
4545       _local_free_list("Local Region List for CSet Freeing") {
4546     }
4547 
4548     virtual bool doHeapRegion(HeapRegion* r) {
4549       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4550 
4551       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4552       g1h->clear_in_cset(r);
4553 
4554       if (r->is_young()) {
4555         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4556                "Young index %d is wrong for region %u of type %s with %u young regions",
4557                r->young_index_in_cset(),
4558                r->hrm_index(),
4559                r->get_type_str(),
4560                g1h->collection_set()->young_region_length());
4561         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4562         r->record_surv_words_in_group(words_survived);
4563       }
4564 
4565       if (!r->evacuation_failed()) {
4566         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4567         _before_used_bytes += r->used();
4568         g1h->free_region(r,
4569                          &_local_free_list,
4570                          true, /* skip_remset */
4571                          true, /* skip_hot_card_cache */
4572                          true  /* locked */);
4573       } else {
4574         r->uninstall_surv_rate_group();
4575         r->set_young_index_in_cset(-1);
4576         r->set_evacuation_failed(false);
4577         // When moving a young gen region to old gen, we "allocate" that whole region
4578         // there. This is in addition to any already evacuated objects. Notify the
4579         // policy about that.
4580         // Old gen regions do not cause an additional allocation: both the objects
4581         // still in the region and the ones already moved are accounted for elsewhere.
4582         if (r->is_young()) {
4583           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4584         }
4585         // The region is now considered to be old.
4586         r->set_old();
4587         // Do some allocation statistics accounting. Regions that failed evacuation
4588         // are always made old, so there is no need to update anything in the young
4589         // gen statistics, but we need to update old gen statistics.
4590         size_t used_words = r->marked_bytes() / HeapWordSize;
4591 
4592         _failure_used_words += used_words;
4593         _failure_waste_words += HeapRegion::GrainWords - used_words;
4594 
4595         g1h->old_set_add(r);
4596         _after_used_bytes += r->used();
4597       }
4598       return false;
4599     }
4600 
4601     void complete_work() {
4602       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4603 
4604       _evacuation_info->set_regions_freed(_local_free_list.length());
4605       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4606 
4607       g1h->prepend_to_freelist(&_local_free_list);
4608       g1h->decrement_summary_bytes(_before_used_bytes);
4609 
4610       G1Policy* policy = g1h->g1_policy();
4611       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4612 
4613       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4614     }
4615   };
4616 
4617   G1CollectionSet* _collection_set;
4618   G1SerialFreeCollectionSetClosure _cl;
4619   const size_t* _surviving_young_words;
4620 
4621   size_t _rs_lengths;
4622 
4623   volatile jint _serial_work_claim;
4624 
4625   struct WorkItem {
4626     uint region_idx;
4627     bool is_young;
4628     bool evacuation_failed;
4629 
4630     WorkItem(HeapRegion* r) {
4631       region_idx = r->hrm_index();
4632       is_young = r->is_young();
4633       evacuation_failed = r->evacuation_failed();
4634     }
4635   };
4636 
4637   volatile size_t _parallel_work_claim;
4638   size_t _num_work_items;
4639   WorkItem* _work_items;
4640 
4641   void do_serial_work() {
4642     // Need to grab the lock to be allowed to modify the old region list.
4643     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4644     _collection_set->iterate(&_cl);
4645   }
4646 
4647   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4648     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4649 
4650     HeapRegion* r = g1h->region_at(region_idx);
4651     assert(!g1h->is_on_master_free_list(r), "sanity");
4652 
4653     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4654 
4655     if (!is_young) {
4656       g1h->_hot_card_cache->reset_card_counts(r);
4657     }
4658 
4659     if (!evacuation_failed) {
4660       r->rem_set()->clear_locked();
4661     }
4662   }
4663 
4664   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4665   private:
4666     size_t _cur_idx;
4667     WorkItem* _work_items;
4668   public:
4669     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4670 
4671     virtual bool doHeapRegion(HeapRegion* r) {
4672       _work_items[_cur_idx++] = WorkItem(r);
4673       return false;
4674     }
4675   };
4676 
4677   void prepare_work() {
4678     G1PrepareFreeCollectionSetClosure cl(_work_items);
4679     _collection_set->iterate(&cl);
4680   }
4681 
4682   void complete_work() {
4683     _cl.complete_work();
4684 
4685     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4686     policy->record_max_rs_lengths(_rs_lengths);
4687     policy->cset_regions_freed();
4688   }
4689 public:
4690   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4691     AbstractGangTask("G1 Free Collection Set"),
4692     _cl(evacuation_info, surviving_young_words),
4693     _collection_set(collection_set),
4694     _surviving_young_words(surviving_young_words),
4695     _serial_work_claim(0),
4696     _rs_lengths(0),
4697     _parallel_work_claim(0),
4698     _num_work_items(collection_set->region_length()),
4699     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4700     prepare_work();
4701   }
4702 
4703   ~G1FreeCollectionSetTask() {
4704     complete_work();
4705     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4706   }
4707 
4708   // Chunk size for work distribution. The chosen value has been determined experimentally
4709   // to be a good tradeoff between overhead and achievable parallelism.
4710   static uint chunk_size() { return 32; }
4711 
4712   virtual void work(uint worker_id) {
4713     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4714 
4715     // Claim serial work.
4716     if (_serial_work_claim == 0) {
4717       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4718       if (value == 0) {
4719         double serial_time = os::elapsedTime();
4720         do_serial_work();
4721         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4722       }
4723     }
4724 
4725     // Start parallel work.
4726     double young_time = 0.0;
4727     bool has_young_time = false;
4728     double non_young_time = 0.0;
4729     bool has_non_young_time = false;
4730 
4731     while (true) {
4732       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4733       size_t cur = end - chunk_size();
4734 
4735       if (cur >= _num_work_items) {
4736         break;
4737       }
4738 
4739       double start_time = os::elapsedTime();
4740 
4741       end = MIN2(end, _num_work_items);
4742 
4743       for (; cur < end; cur++) {
4744         bool is_young = _work_items[cur].is_young;
4745 
4746         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4747 
4748         double end_time = os::elapsedTime();
4749         double time_taken = end_time - start_time;
4750         if (is_young) {
4751           young_time += time_taken;
4752           has_young_time = true;
4753         } else {
4754           non_young_time += time_taken;
4755           has_non_young_time = true;
4756         }
4757         start_time = end_time;
4758       }
4759     }
4760 
4761     if (has_young_time) {
4762       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4763     }
4764     if (has_non_young_time) {
4765       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4766     }
4767   }
4768 };
4769 
4770 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4771   _eden.clear();
4772 
4773   double free_cset_start_time = os::elapsedTime();
4774 
4775   {
4776     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4777     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4778 
4779     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4780 
4781     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4782                         cl.name(),
4783                         num_workers,
4784                         _collection_set.region_length());
4785     workers()->run_task(&cl, num_workers);
4786   }
4787   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4788 
4789   collection_set->clear();
4790 }
4791 
4792 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4793  private:
4794   FreeRegionList* _free_region_list;
4795   HeapRegionSet* _proxy_set;
4796   uint _humongous_objects_reclaimed;
4797   uint _humongous_regions_reclaimed;
4798   size_t _freed_bytes;
4799  public:
4800 
4801   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4802     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4803   }
4804 
4805   virtual bool doHeapRegion(HeapRegion* r) {
4806     if (!r->is_starts_humongous()) {
4807       return false;
4808     }
4809 
4810     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4811 
4812     oop obj = (oop)r->bottom();
4813     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4814 
4815     // The following checks whether the humongous object is live are sufficient.
4816     // The main additional check (in addition to having a reference from the roots
4817     // or the young gen) is whether the humongous object has a remembered set entry.
4818     //
4819     // A humongous object cannot be live if there is no remembered set for it
4820     // because:
4821     // - there can be no references from within humongous starts regions referencing
4822     // the object because we never allocate other objects into them.
4823     // (I.e. there are no intra-region references that may be missed by the
4824     // remembered set)
4825     // - as soon there is a remembered set entry to the humongous starts region
4826     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4827     // until the end of a concurrent mark.
4828     //
4829     // It is not required to check whether the object has been found dead by marking
4830     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4831     // all objects allocated during that time are considered live.
4832     // SATB marking is even more conservative than the remembered set.
4833     // So if at this point in the collection there is no remembered set entry,
4834     // nobody has a reference to it.
4835     // At the start of collection we flush all refinement logs, and remembered sets
4836     // are completely up-to-date wrt to references to the humongous object.
4837     //
4838     // Other implementation considerations:
4839     // - never consider object arrays at this time because they would pose
4840     // considerable effort for cleaning up the the remembered sets. This is
4841     // required because stale remembered sets might reference locations that
4842     // are currently allocated into.
4843     uint region_idx = r->hrm_index();
4844     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4845         !r->rem_set()->is_empty()) {
4846       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",
4847                                region_idx,
4848                                (size_t)obj->size() * HeapWordSize,
4849                                p2i(r->bottom()),
4850                                r->rem_set()->occupied(),
4851                                r->rem_set()->strong_code_roots_list_length(),
4852                                next_bitmap->is_marked(r->bottom()),
4853                                g1h->is_humongous_reclaim_candidate(region_idx),
4854                                obj->is_typeArray()
4855                               );
4856       return false;
4857     }
4858 
4859     guarantee(obj->is_typeArray(),
4860               "Only eagerly reclaiming type arrays is supported, but the object "
4861               PTR_FORMAT " is not.", p2i(r->bottom()));
4862 
4863     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",
4864                              region_idx,
4865                              (size_t)obj->size() * HeapWordSize,
4866                              p2i(r->bottom()),
4867                              r->rem_set()->occupied(),
4868                              r->rem_set()->strong_code_roots_list_length(),
4869                              next_bitmap->is_marked(r->bottom()),
4870                              g1h->is_humongous_reclaim_candidate(region_idx),
4871                              obj->is_typeArray()
4872                             );
4873 
4874     // Need to clear mark bit of the humongous object if already set.
4875     if (next_bitmap->is_marked(r->bottom())) {
4876       next_bitmap->clear(r->bottom());
4877     }
4878     _humongous_objects_reclaimed++;
4879     do {
4880       HeapRegion* next = g1h->next_region_in_humongous(r);
4881       _freed_bytes += r->used();
4882       r->set_containing_set(NULL);
4883       _humongous_regions_reclaimed++;
4884       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4885       r = next;
4886     } while (r != NULL);
4887 
4888     return false;
4889   }
4890 
4891   uint humongous_objects_reclaimed() {
4892     return _humongous_objects_reclaimed;
4893   }
4894 
4895   uint humongous_regions_reclaimed() {
4896     return _humongous_regions_reclaimed;
4897   }
4898 
4899   size_t bytes_freed() const {
4900     return _freed_bytes;
4901   }
4902 };
4903 
4904 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4905   assert_at_safepoint(true);
4906 
4907   if (!G1EagerReclaimHumongousObjects ||
4908       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4909     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4910     return;
4911   }
4912 
4913   double start_time = os::elapsedTime();
4914 
4915   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4916 
4917   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4918   heap_region_iterate(&cl);
4919 
4920   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4921 
4922   G1HRPrinter* hrp = hr_printer();
4923   if (hrp->is_active()) {
4924     FreeRegionListIterator iter(&local_cleanup_list);
4925     while (iter.more_available()) {
4926       HeapRegion* hr = iter.get_next();
4927       hrp->cleanup(hr);
4928     }
4929   }
4930 
4931   prepend_to_freelist(&local_cleanup_list);
4932   decrement_summary_bytes(cl.bytes_freed());
4933 
4934   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4935                                                                     cl.humongous_objects_reclaimed());
4936 }
4937 
4938 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4939 public:
4940   virtual bool doHeapRegion(HeapRegion* r) {
4941     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4942     G1CollectedHeap::heap()->clear_in_cset(r);
4943     r->set_young_index_in_cset(-1);
4944     return false;
4945   }
4946 };
4947 
4948 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4949   G1AbandonCollectionSetClosure cl;
4950   collection_set->iterate(&cl);
4951 
4952   collection_set->clear();
4953   collection_set->stop_incremental_building();
4954 }
4955 
4956 void G1CollectedHeap::set_free_regions_coming() {
4957   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4958 
4959   assert(!free_regions_coming(), "pre-condition");
4960   _free_regions_coming = true;
4961 }
4962 
4963 void G1CollectedHeap::reset_free_regions_coming() {
4964   assert(free_regions_coming(), "pre-condition");
4965 
4966   {
4967     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4968     _free_regions_coming = false;
4969     SecondaryFreeList_lock->notify_all();
4970   }
4971 
4972   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4973 }
4974 
4975 void G1CollectedHeap::wait_while_free_regions_coming() {
4976   // Most of the time we won't have to wait, so let's do a quick test
4977   // first before we take the lock.
4978   if (!free_regions_coming()) {
4979     return;
4980   }
4981 
4982   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4983 
4984   {
4985     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4986     while (free_regions_coming()) {
4987       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4988     }
4989   }
4990 
4991   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4992 }
4993 
4994 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4995   return _allocator->is_retained_old_region(hr);
4996 }
4997 
4998 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4999   _eden.add(hr);
5000   _g1_policy->set_region_eden(hr);
5001 }
5002 
5003 #ifdef ASSERT
5004 
5005 class NoYoungRegionsClosure: public HeapRegionClosure {
5006 private:
5007   bool _success;
5008 public:
5009   NoYoungRegionsClosure() : _success(true) { }
5010   bool doHeapRegion(HeapRegion* r) {
5011     if (r->is_young()) {
5012       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5013                             p2i(r->bottom()), p2i(r->end()));
5014       _success = false;
5015     }
5016     return false;
5017   }
5018   bool success() { return _success; }
5019 };
5020 
5021 bool G1CollectedHeap::check_young_list_empty() {
5022   bool ret = (young_regions_count() == 0);
5023 
5024   NoYoungRegionsClosure closure;
5025   heap_region_iterate(&closure);
5026   ret = ret && closure.success();
5027 
5028   return ret;
5029 }
5030 
5031 #endif // ASSERT
5032 
5033 class TearDownRegionSetsClosure : public HeapRegionClosure {
5034 private:
5035   HeapRegionSet *_old_set;
5036 
5037 public:
5038   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5039 
5040   bool doHeapRegion(HeapRegion* r) {
5041     if (r->is_old()) {
5042       _old_set->remove(r);
5043     } else if(r->is_young()) {
5044       r->uninstall_surv_rate_group();
5045     } else {
5046       // We ignore free regions, we'll empty the free list afterwards.
5047       // We ignore humongous regions, we're not tearing down the
5048       // humongous regions set.
5049       assert(r->is_free() || r->is_humongous(),
5050              "it cannot be another type");
5051     }
5052     return false;
5053   }
5054 
5055   ~TearDownRegionSetsClosure() {
5056     assert(_old_set->is_empty(), "post-condition");
5057   }
5058 };
5059 
5060 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5061   assert_at_safepoint(true /* should_be_vm_thread */);
5062 
5063   if (!free_list_only) {
5064     TearDownRegionSetsClosure cl(&_old_set);
5065     heap_region_iterate(&cl);
5066 
5067     // Note that emptying the _young_list is postponed and instead done as
5068     // the first step when rebuilding the regions sets again. The reason for
5069     // this is that during a full GC string deduplication needs to know if
5070     // a collected region was young or old when the full GC was initiated.
5071   }
5072   _hrm.remove_all_free_regions();
5073 }
5074 
5075 void G1CollectedHeap::increase_used(size_t bytes) {
5076   _summary_bytes_used += bytes;
5077 }
5078 
5079 void G1CollectedHeap::decrease_used(size_t bytes) {
5080   assert(_summary_bytes_used >= bytes,
5081          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5082          _summary_bytes_used, bytes);
5083   _summary_bytes_used -= bytes;
5084 }
5085 
5086 void G1CollectedHeap::set_used(size_t bytes) {
5087   _summary_bytes_used = bytes;
5088 }
5089 
5090 class RebuildRegionSetsClosure : public HeapRegionClosure {
5091 private:
5092   bool            _free_list_only;
5093   HeapRegionSet*   _old_set;
5094   HeapRegionManager*   _hrm;
5095   size_t          _total_used;
5096 
5097 public:
5098   RebuildRegionSetsClosure(bool free_list_only,
5099                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5100     _free_list_only(free_list_only),
5101     _old_set(old_set), _hrm(hrm), _total_used(0) {
5102     assert(_hrm->num_free_regions() == 0, "pre-condition");
5103     if (!free_list_only) {
5104       assert(_old_set->is_empty(), "pre-condition");
5105     }
5106   }
5107 
5108   bool doHeapRegion(HeapRegion* r) {
5109     if (r->is_empty()) {
5110       // Add free regions to the free list
5111       r->set_free();
5112       r->set_allocation_context(AllocationContext::system());
5113       _hrm->insert_into_free_list(r);
5114     } else if (!_free_list_only) {
5115 
5116       if (r->is_humongous()) {
5117         // We ignore humongous regions. We left the humongous set unchanged.
5118       } else {
5119         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5120         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5121         r->move_to_old();
5122         _old_set->add(r);
5123       }
5124       _total_used += r->used();
5125     }
5126 
5127     return false;
5128   }
5129 
5130   size_t total_used() {
5131     return _total_used;
5132   }
5133 };
5134 
5135 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5136   assert_at_safepoint(true /* should_be_vm_thread */);
5137 
5138   if (!free_list_only) {
5139     _eden.clear();
5140     _survivor.clear();
5141   }
5142 
5143   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5144   heap_region_iterate(&cl);
5145 
5146   if (!free_list_only) {
5147     set_used(cl.total_used());
5148     if (_archive_allocator != NULL) {
5149       _archive_allocator->clear_used();
5150     }
5151   }
5152   assert(used_unlocked() == recalculate_used(),
5153          "inconsistent used_unlocked(), "
5154          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5155          used_unlocked(), recalculate_used());
5156 }
5157 
5158 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5159   HeapRegion* hr = heap_region_containing(p);
5160   return hr->is_in(p);
5161 }
5162 
5163 // Methods for the mutator alloc region
5164 
5165 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5166                                                       bool force) {
5167   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5168   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5169   if (force || should_allocate) {
5170     HeapRegion* new_alloc_region = new_region(word_size,
5171                                               false /* is_old */,
5172                                               false /* do_expand */);
5173     if (new_alloc_region != NULL) {
5174       set_region_short_lived_locked(new_alloc_region);
5175       _hr_printer.alloc(new_alloc_region, !should_allocate);
5176       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5177       return new_alloc_region;
5178     }
5179   }
5180   return NULL;
5181 }
5182 
5183 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5184                                                   size_t allocated_bytes) {
5185   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5186   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5187 
5188   collection_set()->add_eden_region(alloc_region);
5189   increase_used(allocated_bytes);
5190   _hr_printer.retire(alloc_region);
5191   // We update the eden sizes here, when the region is retired,
5192   // instead of when it's allocated, since this is the point that its
5193   // used space has been recored in _summary_bytes_used.
5194   g1mm()->update_eden_size();
5195 }
5196 
5197 // Methods for the GC alloc regions
5198 
5199 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5200   if (dest.is_old()) {
5201     return true;
5202   } else {
5203     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5204   }
5205 }
5206 
5207 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5208   assert(FreeList_lock->owned_by_self(), "pre-condition");
5209 
5210   if (!has_more_regions(dest)) {
5211     return NULL;
5212   }
5213 
5214   const bool is_survivor = dest.is_young();
5215 
5216   HeapRegion* new_alloc_region = new_region(word_size,
5217                                             !is_survivor,
5218                                             true /* do_expand */);
5219   if (new_alloc_region != NULL) {
5220     // We really only need to do this for old regions given that we
5221     // should never scan survivors. But it doesn't hurt to do it
5222     // for survivors too.
5223     new_alloc_region->record_timestamp();
5224     if (is_survivor) {
5225       new_alloc_region->set_survivor();
5226       _survivor.add(new_alloc_region);
5227       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5228     } else {
5229       new_alloc_region->set_old();
5230       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5231     }
5232     _hr_printer.alloc(new_alloc_region);
5233     bool during_im = collector_state()->during_initial_mark_pause();
5234     new_alloc_region->note_start_of_copying(during_im);
5235     return new_alloc_region;
5236   }
5237   return NULL;
5238 }
5239 
5240 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5241                                              size_t allocated_bytes,
5242                                              InCSetState dest) {
5243   bool during_im = collector_state()->during_initial_mark_pause();
5244   alloc_region->note_end_of_copying(during_im);
5245   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5246   if (dest.is_old()) {
5247     _old_set.add(alloc_region);
5248   }
5249   _hr_printer.retire(alloc_region);
5250 }
5251 
5252 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5253   bool expanded = false;
5254   uint index = _hrm.find_highest_free(&expanded);
5255 
5256   if (index != G1_NO_HRM_INDEX) {
5257     if (expanded) {
5258       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5259                                 HeapRegion::GrainWords * HeapWordSize);
5260     }
5261     _hrm.allocate_free_regions_starting_at(index, 1);
5262     return region_at(index);
5263   }
5264   return NULL;
5265 }
5266 
5267 // Optimized nmethod scanning
5268 
5269 class RegisterNMethodOopClosure: public OopClosure {
5270   G1CollectedHeap* _g1h;
5271   nmethod* _nm;
5272 
5273   template <class T> void do_oop_work(T* p) {
5274     T heap_oop = oopDesc::load_heap_oop(p);
5275     if (!oopDesc::is_null(heap_oop)) {
5276       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5277       HeapRegion* hr = _g1h->heap_region_containing(obj);
5278       assert(!hr->is_continues_humongous(),
5279              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5280              " starting at " HR_FORMAT,
5281              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5282 
5283       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5284       hr->add_strong_code_root_locked(_nm);
5285     }
5286   }
5287 
5288 public:
5289   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5290     _g1h(g1h), _nm(nm) {}
5291 
5292   void do_oop(oop* p)       { do_oop_work(p); }
5293   void do_oop(narrowOop* p) { do_oop_work(p); }
5294 };
5295 
5296 class UnregisterNMethodOopClosure: public OopClosure {
5297   G1CollectedHeap* _g1h;
5298   nmethod* _nm;
5299 
5300   template <class T> void do_oop_work(T* p) {
5301     T heap_oop = oopDesc::load_heap_oop(p);
5302     if (!oopDesc::is_null(heap_oop)) {
5303       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5304       HeapRegion* hr = _g1h->heap_region_containing(obj);
5305       assert(!hr->is_continues_humongous(),
5306              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5307              " starting at " HR_FORMAT,
5308              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5309 
5310       hr->remove_strong_code_root(_nm);
5311     }
5312   }
5313 
5314 public:
5315   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5316     _g1h(g1h), _nm(nm) {}
5317 
5318   void do_oop(oop* p)       { do_oop_work(p); }
5319   void do_oop(narrowOop* p) { do_oop_work(p); }
5320 };
5321 
5322 // Returns true if the reference points to an object that
5323 // can move in an incremental collection.
5324 bool G1CollectedHeap::is_scavengable(oop obj) {
5325   HeapRegion* hr = heap_region_containing(obj);
5326   return !hr->is_pinned();
5327 }
5328 
5329 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5330   guarantee(nm != NULL, "sanity");
5331   RegisterNMethodOopClosure reg_cl(this, nm);
5332   nm->oops_do(&reg_cl);
5333 }
5334 
5335 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5336   guarantee(nm != NULL, "sanity");
5337   UnregisterNMethodOopClosure reg_cl(this, nm);
5338   nm->oops_do(&reg_cl, true);
5339 }
5340 
5341 void G1CollectedHeap::purge_code_root_memory() {
5342   double purge_start = os::elapsedTime();
5343   G1CodeRootSet::purge();
5344   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5345   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5346 }
5347 
5348 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5349   G1CollectedHeap* _g1h;
5350 
5351 public:
5352   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5353     _g1h(g1h) {}
5354 
5355   void do_code_blob(CodeBlob* cb) {
5356     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5357     if (nm == NULL) {
5358       return;
5359     }
5360 
5361     if (ScavengeRootsInCode) {
5362       _g1h->register_nmethod(nm);
5363     }
5364   }
5365 };
5366 
5367 void G1CollectedHeap::rebuild_strong_code_roots() {
5368   RebuildStrongCodeRootClosure blob_cl(this);
5369   CodeCache::blobs_do(&blob_cl);















5370 }
--- EOF ---