8196341: Add JFR events for parallel phases of G1

0 /*
1  * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3  *
4  * This code is free software; you can redistribute it and/or modify it
5  * under the terms of the GNU General Public License version 2 only, as
6  * published by the Free Software Foundation.
7  *
8  * This code is distributed in the hope that it will be useful, but WITHOUT
9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
11  * version 2 for more details (a copy is included in the LICENSE file that
12  * accompanied this code).
13  *
14  * You should have received a copy of the GNU General Public License version
15  * 2 along with this work; if not, write to the Free Software Foundation,
16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17  *
18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19  * or visit www.oracle.com if you need additional information or have any
20  * questions.
21  *
22  */
23 
24 #include "precompiled.hpp"
25 #include "classfile/metadataOnStackMark.hpp"
26 #include "classfile/stringTable.hpp"
27 #include "code/codeCache.hpp"
28 #include "code/icBuffer.hpp"
29 #include "gc/g1/g1Allocator.inline.hpp"
30 #include "gc/g1/g1BarrierSet.hpp"
31 #include "gc/g1/g1CollectedHeap.inline.hpp"
32 #include "gc/g1/g1CollectionSet.hpp"
33 #include "gc/g1/g1CollectorPolicy.hpp"
34 #include "gc/g1/g1CollectorState.hpp"
35 #include "gc/g1/g1ConcurrentRefine.hpp"
36 #include "gc/g1/g1ConcurrentRefineThread.hpp"
37 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
38 #include "gc/g1/g1EvacStats.inline.hpp"
39 #include "gc/g1/g1FullCollector.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1HeapSizingPolicy.hpp"
42 #include "gc/g1/g1HeapTransition.hpp"
43 #include "gc/g1/g1HeapVerifier.hpp"
44 #include "gc/g1/g1HotCardCache.hpp"
45 #include "gc/g1/g1MemoryPool.hpp"
46 #include "gc/g1/g1OopClosures.inline.hpp"
47 #include "gc/g1/g1ParScanThreadState.inline.hpp"
48 #include "gc/g1/g1Policy.hpp"
49 #include "gc/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc/g1/g1RemSet.hpp"
51 #include "gc/g1/g1RootClosures.hpp"
52 #include "gc/g1/g1RootProcessor.hpp"
53 #include "gc/g1/g1SATBMarkQueueSet.hpp"
54 #include "gc/g1/g1StringDedup.hpp"
55 #include "gc/g1/g1ThreadLocalData.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
58 #include "gc/g1/heapRegion.inline.hpp"
59 #include "gc/g1/heapRegionRemSet.hpp"
60 #include "gc/g1/heapRegionSet.inline.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/adaptiveSizePolicy.hpp"
63 #include "gc/shared/gcHeapSummary.hpp"
64 #include "gc/shared/gcId.hpp"
65 #include "gc/shared/gcLocker.hpp"
66 #include "gc/shared/gcTimer.hpp"
67 #include "gc/shared/gcTrace.hpp"
68 #include "gc/shared/gcTraceTime.inline.hpp"
69 #include "gc/shared/generationSpec.hpp"
70 #include "gc/shared/isGCActiveMark.hpp"
71 #include "gc/shared/oopStorageParState.hpp"
72 #include "gc/shared/parallelCleaning.hpp"
73 #include "gc/shared/preservedMarks.inline.hpp"
74 #include "gc/shared/suspendibleThreadSet.hpp"
75 #include "gc/shared/referenceProcessor.inline.hpp"
76 #include "gc/shared/taskqueue.inline.hpp"
77 #include "gc/shared/weakProcessor.inline.hpp"
78 #include "logging/log.hpp"
79 #include "memory/allocation.hpp"
80 #include "memory/iterator.hpp"
81 #include "memory/metaspaceShared.hpp"
82 #include "memory/resourceArea.hpp"
83 #include "oops/access.inline.hpp"
84 #include "oops/compressedOops.inline.hpp"
85 #include "oops/oop.inline.hpp"
86 #include "runtime/atomic.hpp"
87 #include "runtime/flags/flagSetting.hpp"
88 #include "runtime/handles.inline.hpp"
89 #include "runtime/init.hpp"
90 #include "runtime/orderAccess.hpp"
91 #include "runtime/threadSMR.hpp"
92 #include "runtime/vmThread.hpp"
93 #include "utilities/align.hpp"
94 #include "utilities/globalDefinitions.hpp"
95 #include "utilities/stack.inline.hpp"
96 
97 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
98 
99 // INVARIANTS/NOTES
100 //
101 // All allocation activity covered by the G1CollectedHeap interface is
102 // serialized by acquiring the HeapLock.  This happens in mem_allocate
103 // and allocate_new_tlab, which are the "entry" points to the
104 // allocation code from the rest of the JVM.  (Note that this does not
105 // apply to TLAB allocation, which is not part of this interface: it
106 // is done by clients of this interface.)
107 
108 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
109  private:
110   size_t _num_dirtied;
111   G1CollectedHeap* _g1h;
112   G1CardTable* _g1_ct;
113 
114   HeapRegion* region_for_card(jbyte* card_ptr) const {
115     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
116   }
117 
118   bool will_become_free(HeapRegion* hr) const {
119     // A region will be freed by free_collection_set if the region is in the
120     // collection set and has not had an evacuation failure.
121     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
122   }
123 
124  public:
125   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
126     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
127 
128   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
129     HeapRegion* hr = region_for_card(card_ptr);
130 
131     // Should only dirty cards in regions that won't be freed.
132     if (!will_become_free(hr)) {
133       *card_ptr = G1CardTable::dirty_card_val();
134       _num_dirtied++;
135     }
136 
137     return true;
138   }
139 
140   size_t num_dirtied()   const { return _num_dirtied; }
141 };
142 
143 
144 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
145   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
146 }
147 
148 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
149   // The from card cache is not the memory that is actually committed. So we cannot
150   // take advantage of the zero_filled parameter.
151   reset_from_card_cache(start_idx, num_regions);
152 }
153 
154 
155 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
156                                              MemRegion mr) {
157   return new HeapRegion(hrs_index, bot(), mr);
158 }
159 
160 // Private methods.
161 
162 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
163   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
164          "the only time we use this to allocate a humongous region is "
165          "when we are allocating a single humongous region");
166 
167   HeapRegion* res = _hrm.allocate_free_region(is_old);
168 
169   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
170     // Currently, only attempts to allocate GC alloc regions set
171     // do_expand to true. So, we should only reach here during a
172     // safepoint. If this assumption changes we might have to
173     // reconsider the use of _expand_heap_after_alloc_failure.
174     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
175 
176     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT
177                               word_size * HeapWordSize);
178 
179     if (expand(word_size * HeapWordSize)) {
180       // Given that expand() succeeded in expanding the heap, and we
181       // always expand the heap by an amount aligned to the heap
182       // region size, the free list should in theory not be empty.
183       // In either case allocate_free_region() will check for NULL.
184       res = _hrm.allocate_free_region(is_old);
185     } else {
186       _expand_heap_after_alloc_failure = false;
187     }
188   }
189   return res;
190 }
191 
192 HeapWord*
193 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
194                                                            uint num_regions,
195                                                            size_t word_size) {
196   assert(first != G1_NO_HRM_INDEX, "pre-condition");
197   assert(is_humongous(word_size), "word_size should be humongous");
198   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
199 
200   // Index of last region in the series.
201   uint last = first + num_regions - 1;
202 
203   // We need to initialize the region(s) we just discovered. This is
204   // a bit tricky given that it can happen concurrently with
205   // refinement threads refining cards on these regions and
206   // potentially wanting to refine the BOT as they are scanning
207   // those cards (this can happen shortly after a cleanup; see CR
208   // 6991377). So we have to set up the region(s) carefully and in
209   // a specific order.
210 
211   // The word size sum of all the regions we will allocate.
212   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
213   assert(word_size <= word_size_sum, "sanity");
214 
215   // This will be the "starts humongous" region.
216   HeapRegion* first_hr = region_at(first);
217   // The header of the new object will be placed at the bottom of
218   // the first region.
219   HeapWord* new_obj = first_hr->bottom();
220   // This will be the new top of the new object.
221   HeapWord* obj_top = new_obj + word_size;
222 
223   // First, we need to zero the header of the space that we will be
224   // allocating. When we update top further down, some refinement
225   // threads might try to scan the region. By zeroing the header we
226   // ensure that any thread that will try to scan the region will
227   // come across the zero klass word and bail out.
228   //
229   // NOTE: It would not have been correct to have used
230   // CollectedHeap::fill_with_object() and make the space look like
231   // an int array. The thread that is doing the allocation will
232   // later update the object header to a potentially different array
233   // type and, for a very short period of time, the klass and length
234   // fields will be inconsistent. This could cause a refinement
235   // thread to calculate the object size incorrectly.
236   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
237 
238   // Next, pad out the unused tail of the last region with filler
239   // objects, for improved usage accounting.
240   // How many words we use for filler objects.
241   size_t word_fill_size = word_size_sum - word_size;
242 
243   // How many words memory we "waste" which cannot hold a filler object.
244   size_t words_not_fillable = 0;
245 
246   if (word_fill_size >= min_fill_size()) {
247     fill_with_objects(obj_top, word_fill_size);
248   } else if (word_fill_size > 0) {
249     // We have space to fill, but we cannot fit an object there.
250     words_not_fillable = word_fill_size;
251     word_fill_size = 0;
252   }
253 
254   // We will set up the first region as "starts humongous". This
255   // will also update the BOT covering all the regions to reflect
256   // that there is a single object that starts at the bottom of the
257   // first region.
258   first_hr->set_starts_humongous(obj_top, word_fill_size);
259   _g1_policy->remset_tracker()->update_at_allocate(first_hr);
260   // Then, if there are any, we will set up the "continues
261   // humongous" regions.
262   HeapRegion* hr = NULL;
263   for (uint i = first + 1; i <= last; ++i) {
264     hr = region_at(i);
265     hr->set_continues_humongous(first_hr);
266     _g1_policy->remset_tracker()->update_at_allocate(hr);
267   }
268 
269   // Up to this point no concurrent thread would have been able to
270   // do any scanning on any region in this series. All the top
271   // fields still point to bottom, so the intersection between
272   // [bottom,top] and [card_start,card_end] will be empty. Before we
273   // update the top fields, we'll do a storestore to make sure that
274   // no thread sees the update to top before the zeroing of the
275   // object header and the BOT initialization.
276   OrderAccess::storestore();
277 
278   // Now, we will update the top fields of the "continues humongous"
279   // regions except the last one.
280   for (uint i = first; i < last; ++i) {
281     hr = region_at(i);
282     hr->set_top(hr->end());
283   }
284 
285   hr = region_at(last);
286   // If we cannot fit a filler object, we must set top to the end
287   // of the humongous object, otherwise we cannot iterate the heap
288   // and the BOT will not be complete.
289   hr->set_top(hr->end() - words_not_fillable);
290 
291   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
292          "obj_top should be in last region");
293 
294   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
295 
296   assert(words_not_fillable == 0 ||
297          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
298          "Miscalculation in humongous allocation");
299 
300   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
301 
302   for (uint i = first; i <= last; ++i) {
303     hr = region_at(i);
304     _humongous_set.add(hr);
305     _hr_printer.alloc(hr);
306   }
307 
308   return new_obj;
309 }
310 
311 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
312   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
313   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
314 }
315 
316 // If could fit into free regions w/o expansion, try.
317 // Otherwise, if can expand, do so.
318 // Otherwise, if using ex regions might help, try with ex given back.
319 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
320   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
321 
322   _verifier->verify_region_sets_optional();
323 
324   uint first = G1_NO_HRM_INDEX;
325   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
326 
327   if (obj_regions == 1) {
328     // Only one region to allocate, try to use a fast path by directly allocating
329     // from the free lists. Do not try to expand here, we will potentially do that
330     // later.
331     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
332     if (hr != NULL) {
333       first = hr->hrm_index();
334     }
335   } else {
336     // Policy: Try only empty regions (i.e. already committed first). Maybe we
337     // are lucky enough to find some.
338     first = _hrm.find_contiguous_only_empty(obj_regions);
339     if (first != G1_NO_HRM_INDEX) {
340       _hrm.allocate_free_regions_starting_at(first, obj_regions);
341     }
342   }
343 
344   if (first == G1_NO_HRM_INDEX) {
345     // Policy: We could not find enough regions for the humongous object in the
346     // free list. Look through the heap to find a mix of free and uncommitted regions.
347     // If so, try expansion.
348     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
349     if (first != G1_NO_HRM_INDEX) {
350       // We found something. Make sure these regions are committed, i.e. expand
351       // the heap. Alternatively we could do a defragmentation GC.
352       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_F
353                                     word_size * HeapWordSize);
354 
355       _hrm.expand_at(first, obj_regions, workers());
356       g1_policy()->record_new_heap_size(num_regions());
357 
358 #ifdef ASSERT
359       for (uint i = first; i < first + obj_regions; ++i) {
360         HeapRegion* hr = region_at(i);
361         assert(hr->is_free(), "sanity");
362         assert(hr->is_empty(), "sanity");
363         assert(is_on_master_free_list(hr), "sanity");
364       }
365 #endif
366       _hrm.allocate_free_regions_starting_at(first, obj_regions);
367     } else {
368       // Policy: Potentially trigger a defragmentation GC.
369     }
370   }
371 
372   HeapWord* result = NULL;
373   if (first != G1_NO_HRM_INDEX) {
374     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
375     assert(result != NULL, "it should always return a valid result");
376 
377     // A successful humongous object allocation changes the used space
378     // information of the old generation so we need to recalculate the
379     // sizes and update the jstat counters here.
380     g1mm()->update_sizes();
381   }
382 
383   _verifier->verify_region_sets_optional();
384 
385   return result;
386 }
387 
388 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
389                                              size_t requested_size,
390                                              size_t* actual_size) {
391   assert_heap_not_locked_and_not_at_safepoint();
392   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
393 
394   return attempt_allocation(min_size, requested_size, actual_size);
395 }
396 
397 HeapWord*
398 G1CollectedHeap::mem_allocate(size_t word_size,
399                               bool*  gc_overhead_limit_was_exceeded) {
400   assert_heap_not_locked_and_not_at_safepoint();
401 
402   if (is_humongous(word_size)) {
403     return attempt_allocation_humongous(word_size);
404   }
405   size_t dummy = 0;
406   return attempt_allocation(word_size, word_size, &dummy);
407 }
408 
409 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
410   ResourceMark rm; // For retrieving the thread names in log messages.
411 
412   // Make sure you read the note in attempt_allocation_humongous().
413 
414   assert_heap_not_locked_and_not_at_safepoint();
415   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
416          "be called for humongous allocation requests");
417 
418   // We should only get here after the first-level allocation attempt
419   // (attempt_allocation()) failed to allocate.
420 
421   // We will loop until a) we manage to successfully perform the
422   // allocation or b) we successfully schedule a collection which
423   // fails to perform the allocation. b) is the only case when we'll
424   // return NULL.
425   HeapWord* result = NULL;
426   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
427     bool should_try_gc;
428     uint gc_count_before;
429 
430     {
431       MutexLockerEx x(Heap_lock);
432       result = _allocator->attempt_allocation_locked(word_size);
433       if (result != NULL) {
434         return result;
435       }
436 
437       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
438       // This is different to when only GCLocker::needs_gc() is set: try to avoid
439       // waiting because the GCLocker is active to not wait too long.
440       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
441         // No need for an ergo message here, can_expand_young_list() does this when
442         // it returns true.
443         result = _allocator->attempt_allocation_force(word_size);
444         if (result != NULL) {
445           return result;
446         }
447       }
448       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
449       // the GCLocker initiated GC has been performed and then retry. This includes
450       // the case when the GC Locker is not active but has not been performed.
451       should_try_gc = !GCLocker::needs_gc();
452       // Read the GC count while still holding the Heap_lock.
453       gc_count_before = total_collections();
454     }
455 
456     if (should_try_gc) {
457       bool succeeded;
458       result = do_collection_pause(word_size, gc_count_before, &succeeded,
459                                    GCCause::_g1_inc_collection_pause);
460       if (result != NULL) {
461         assert(succeeded, "only way to get back a non-NULL result");
462         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
463                              Thread::current()->name(), p2i(result));
464         return result;
465       }
466 
467       if (succeeded) {
468         // We successfully scheduled a collection which failed to allocate. No
469         // point in trying to allocate further. We'll just return NULL.
470         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
471                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
472         return NULL;
473       }
474       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
475                            Thread::current()->name(), word_size);
476     } else {
477       // Failed to schedule a collection.
478       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
479         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
480                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
481         return NULL;
482       }
483       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
484       // The GCLocker is either active or the GCLocker initiated
485       // GC has not yet been performed. Stall until it is and
486       // then retry the allocation.
487       GCLocker::stall_until_clear();
488       gclocker_retry_count += 1;
489     }
490 
491     // We can reach here if we were unsuccessful in scheduling a
492     // collection (because another thread beat us to it) or if we were
493     // stalled due to the GC locker. In either can we should retry the
494     // allocation attempt in case another thread successfully
495     // performed a collection and reclaimed enough space. We do the
496     // first attempt (without holding the Heap_lock) here and the
497     // follow-on attempt will be at the start of the next loop
498     // iteration (after taking the Heap_lock).
499     size_t dummy = 0;
500     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
501     if (result != NULL) {
502       return result;
503     }
504 
505     // Give a warning if we seem to be looping forever.
506     if ((QueuedAllocationWarningCount > 0) &&
507         (try_count % QueuedAllocationWarningCount == 0)) {
508       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
509                              Thread::current()->name(), try_count, word_size);
510     }
511   }
512 
513   ShouldNotReachHere();
514   return NULL;
515 }
516 
517 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
518   assert_at_safepoint_on_vm_thread();
519   if (_archive_allocator == NULL) {
520     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
521   }
522 }
523 
524 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
525   // Allocations in archive regions cannot be of a size that would be considered
526   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
527   // may be different at archive-restore time.
528   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
529 }
530 
531 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
532   assert_at_safepoint_on_vm_thread();
533   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
534   if (is_archive_alloc_too_large(word_size)) {
535     return NULL;
536   }
537   return _archive_allocator->archive_mem_allocate(word_size);
538 }
539 
540 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
541                                               size_t end_alignment_in_bytes) {
542   assert_at_safepoint_on_vm_thread();
543   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
544 
545   // Call complete_archive to do the real work, filling in the MemRegion
546   // array with the archive regions.
547   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
548   delete _archive_allocator;
549   _archive_allocator = NULL;
550 }
551 
552 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
553   assert(ranges != NULL, "MemRegion array NULL");
554   assert(count != 0, "No MemRegions provided");
555   MemRegion reserved = _hrm.reserved();
556   for (size_t i = 0; i < count; i++) {
557     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
558       return false;
559     }
560   }
561   return true;
562 }
563 
564 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
565                                             size_t count,
566                                             bool open) {
567   assert(!is_init_completed(), "Expect to be called at JVM init time");
568   assert(ranges != NULL, "MemRegion array NULL");
569   assert(count != 0, "No MemRegions provided");
570   MutexLockerEx x(Heap_lock);
571 
572   MemRegion reserved = _hrm.reserved();
573   HeapWord* prev_last_addr = NULL;
574   HeapRegion* prev_last_region = NULL;
575 
576   // Temporarily disable pretouching of heap pages. This interface is used
577   // when mmap'ing archived heap data in, so pre-touching is wasted.
578   FlagSetting fs(AlwaysPreTouch, false);
579 
580   // Enable archive object checking used by G1MarkSweep. We have to let it know
581   // about each archive range, so that objects in those ranges aren't marked.
582   G1ArchiveAllocator::enable_archive_object_check();
583 
584   // For each specified MemRegion range, allocate the corresponding G1
585   // regions and mark them as archive regions. We expect the ranges
586   // in ascending starting address order, without overlap.
587   for (size_t i = 0; i < count; i++) {
588     MemRegion curr_range = ranges[i];
589     HeapWord* start_address = curr_range.start();
590     size_t word_size = curr_range.word_size();
591     HeapWord* last_address = curr_range.last();
592     size_t commits = 0;
593 
594     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
595               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
596               p2i(start_address), p2i(last_address));
597     guarantee(start_address > prev_last_addr,
598               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
599               p2i(start_address), p2i(prev_last_addr));
600     prev_last_addr = last_address;
601 
602     // Check for ranges that start in the same G1 region in which the previous
603     // range ended, and adjust the start address so we don't try to allocate
604     // the same region again. If the current range is entirely within that
605     // region, skip it, just adjusting the recorded top.
606     HeapRegion* start_region = _hrm.addr_to_region(start_address);
607     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
608       start_address = start_region->end();
609       if (start_address > last_address) {
610         increase_used(word_size * HeapWordSize);
611         start_region->set_top(last_address + 1);
612         continue;
613       }
614       start_region->set_top(start_address);
615       curr_range = MemRegion(start_address, last_address + 1);
616       start_region = _hrm.addr_to_region(start_address);
617     }
618 
619     // Perform the actual region allocation, exiting if it fails.
620     // Then note how much new space we have allocated.
621     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
622       return false;
623     }
624     increase_used(word_size * HeapWordSize);
625     if (commits != 0) {
626       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
627                                 HeapRegion::GrainWords * HeapWordSize * commits);
628 
629     }
630 
631     // Mark each G1 region touched by the range as archive, add it to
632     // the old set, and set top.
633     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
634     HeapRegion* last_region = _hrm.addr_to_region(last_address);
635     prev_last_region = last_region;
636 
637     while (curr_region != NULL) {
638       assert(curr_region->is_empty() && !curr_region->is_pinned(),
639              "Region already in use (index %u)", curr_region->hrm_index());
640       if (open) {
641         curr_region->set_open_archive();
642       } else {
643         curr_region->set_closed_archive();
644       }
645       _hr_printer.alloc(curr_region);
646       _archive_set.add(curr_region);
647       HeapWord* top;
648       HeapRegion* next_region;
649       if (curr_region != last_region) {
650         top = curr_region->end();
651         next_region = _hrm.next_region_in_heap(curr_region);
652       } else {
653         top = last_address + 1;
654         next_region = NULL;
655       }
656       curr_region->set_top(top);
657       curr_region->set_first_dead(top);
658       curr_region->set_end_of_live(top);
659       curr_region = next_region;
660     }
661 
662     // Notify mark-sweep of the archive
663     G1ArchiveAllocator::set_range_archive(curr_range, open);
664   }
665   return true;
666 }
667 
668 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
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   MemRegion reserved = _hrm.reserved();
673   HeapWord *prev_last_addr = NULL;
674   HeapRegion* prev_last_region = NULL;
675 
676   // For each MemRegion, create filler objects, if needed, in the G1 regions
677   // that contain the address range. The address range actually within the
678   // MemRegion will not be modified. That is assumed to have been initialized
679   // elsewhere, probably via an mmap of archived heap data.
680   MutexLockerEx x(Heap_lock);
681   for (size_t i = 0; i < count; i++) {
682     HeapWord* start_address = ranges[i].start();
683     HeapWord* last_address = ranges[i].last();
684 
685     assert(reserved.contains(start_address) && reserved.contains(last_address),
686            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
687            p2i(start_address), p2i(last_address));
688     assert(start_address > prev_last_addr,
689            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
690            p2i(start_address), p2i(prev_last_addr));
691 
692     HeapRegion* start_region = _hrm.addr_to_region(start_address);
693     HeapRegion* last_region = _hrm.addr_to_region(last_address);
694     HeapWord* bottom_address = start_region->bottom();
695 
696     // Check for a range beginning in the same region in which the
697     // previous one ended.
698     if (start_region == prev_last_region) {
699       bottom_address = prev_last_addr + 1;
700     }
701 
702     // Verify that the regions were all marked as archive regions by
703     // alloc_archive_regions.
704     HeapRegion* curr_region = start_region;
705     while (curr_region != NULL) {
706       guarantee(curr_region->is_archive(),
707                 "Expected archive region at index %u", curr_region->hrm_index());
708       if (curr_region != last_region) {
709         curr_region = _hrm.next_region_in_heap(curr_region);
710       } else {
711         curr_region = NULL;
712       }
713     }
714 
715     prev_last_addr = last_address;
716     prev_last_region = last_region;
717 
718     // Fill the memory below the allocated range with dummy object(s),
719     // if the region bottom does not match the range start, or if the previous
720     // range ended within the same G1 region, and there is a gap.
721     if (start_address != bottom_address) {
722       size_t fill_size = pointer_delta(start_address, bottom_address);
723       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
724       increase_used(fill_size * HeapWordSize);
725     }
726   }
727 }
728 
729 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
730                                                      size_t desired_word_size,
731                                                      size_t* actual_word_size) {
732   assert_heap_not_locked_and_not_at_safepoint();
733   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
734          "be called for humongous allocation requests");
735 
736   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
737 
738   if (result == NULL) {
739     *actual_word_size = desired_word_size;
740     result = attempt_allocation_slow(desired_word_size);
741   }
742 
743   assert_heap_not_locked();
744   if (result != NULL) {
745     assert(*actual_word_size != 0, "Actual size must have been set here");
746     dirty_young_block(result, *actual_word_size);
747   } else {
748     *actual_word_size = 0;
749   }
750 
751   return result;
752 }
753 
754 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
755   assert(!is_init_completed(), "Expect to be called at JVM init time");
756   assert(ranges != NULL, "MemRegion array NULL");
757   assert(count != 0, "No MemRegions provided");
758   MemRegion reserved = _hrm.reserved();
759   HeapWord* prev_last_addr = NULL;
760   HeapRegion* prev_last_region = NULL;
761   size_t size_used = 0;
762   size_t uncommitted_regions = 0;
763 
764   // For each Memregion, free the G1 regions that constitute it, and
765   // notify mark-sweep that the range is no longer to be considered 'archive.'
766   MutexLockerEx x(Heap_lock);
767   for (size_t i = 0; i < count; i++) {
768     HeapWord* start_address = ranges[i].start();
769     HeapWord* last_address = ranges[i].last();
770 
771     assert(reserved.contains(start_address) && reserved.contains(last_address),
772            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
773            p2i(start_address), p2i(last_address));
774     assert(start_address > prev_last_addr,
775            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
776            p2i(start_address), p2i(prev_last_addr));
777     size_used += ranges[i].byte_size();
778     prev_last_addr = last_address;
779 
780     HeapRegion* start_region = _hrm.addr_to_region(start_address);
781     HeapRegion* last_region = _hrm.addr_to_region(last_address);
782 
783     // Check for ranges that start in the same G1 region in which the previous
784     // range ended, and adjust the start address so we don't try to free
785     // the same region again. If the current range is entirely within that
786     // region, skip it.
787     if (start_region == prev_last_region) {
788       start_address = start_region->end();
789       if (start_address > last_address) {
790         continue;
791       }
792       start_region = _hrm.addr_to_region(start_address);
793     }
794     prev_last_region = last_region;
795 
796     // After verifying that each region was marked as an archive region by
797     // alloc_archive_regions, set it free and empty and uncommit it.
798     HeapRegion* curr_region = start_region;
799     while (curr_region != NULL) {
800       guarantee(curr_region->is_archive(),
801                 "Expected archive region at index %u", curr_region->hrm_index());
802       uint curr_index = curr_region->hrm_index();
803       _archive_set.remove(curr_region);
804       curr_region->set_free();
805       curr_region->set_top(curr_region->bottom());
806       if (curr_region != last_region) {
807         curr_region = _hrm.next_region_in_heap(curr_region);
808       } else {
809         curr_region = NULL;
810       }
811       _hrm.shrink_at(curr_index, 1);
812       uncommitted_regions++;
813     }
814 
815     // Notify mark-sweep that this is no longer an archive range.
816     G1ArchiveAllocator::set_range_archive(ranges[i], false);
817   }
818 
819   if (uncommitted_regions != 0) {
820     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
821                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
822   }
823   decrease_used(size_used);
824 }
825 
826 oop G1CollectedHeap::materialize_archived_object(oop obj) {
827   assert(obj != NULL, "archived obj is NULL");
828   assert(MetaspaceShared::is_archive_object(obj), "must be archived object");
829 
830   // Loading an archived object makes it strongly reachable. If it is
831   // loaded during concurrent marking, it must be enqueued to the SATB
832   // queue, shading the previously white object gray.
833   G1BarrierSet::enqueue(obj);
834 
835   return obj;
836 }
837 
838 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
839   ResourceMark rm; // For retrieving the thread names in log messages.
840 
841   // The structure of this method has a lot of similarities to
842   // attempt_allocation_slow(). The reason these two were not merged
843   // into a single one is that such a method would require several "if
844   // allocation is not humongous do this, otherwise do that"
845   // conditional paths which would obscure its flow. In fact, an early
846   // version of this code did use a unified method which was harder to
847   // follow and, as a result, it had subtle bugs that were hard to
848   // track down. So keeping these two methods separate allows each to
849   // be more readable. It will be good to keep these two in sync as
850   // much as possible.
851 
852   assert_heap_not_locked_and_not_at_safepoint();
853   assert(is_humongous(word_size), "attempt_allocation_humongous() "
854          "should only be called for humongous allocations");
855 
856   // Humongous objects can exhaust the heap quickly, so we should check if we
857   // need to start a marking cycle at each humongous object allocation. We do
858   // the check before we do the actual allocation. The reason for doing it
859   // before the allocation is that we avoid having to keep track of the newly
860   // allocated memory while we do a GC.
861   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
862                                            word_size)) {
863     collect(GCCause::_g1_humongous_allocation);
864   }
865 
866   // We will loop until a) we manage to successfully perform the
867   // allocation or b) we successfully schedule a collection which
868   // fails to perform the allocation. b) is the only case when we'll
869   // return NULL.
870   HeapWord* result = NULL;
871   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
872     bool should_try_gc;
873     uint gc_count_before;
874 
875 
876     {
877       MutexLockerEx x(Heap_lock);
878 
879       // Given that humongous objects are not allocated in young
880       // regions, we'll first try to do the allocation without doing a
881       // collection hoping that there's enough space in the heap.
882       result = humongous_obj_allocate(word_size);
883       if (result != NULL) {
884         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
885         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
886         return result;
887       }
888 
889       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
890       // the GCLocker initiated GC has been performed and then retry. This includes
891       // the case when the GC Locker is not active but has not been performed.
892       should_try_gc = !GCLocker::needs_gc();
893       // Read the GC count while still holding the Heap_lock.
894       gc_count_before = total_collections();
895     }
896 
897     if (should_try_gc) {
898       bool succeeded;
899       result = do_collection_pause(word_size, gc_count_before, &succeeded,
900                                    GCCause::_g1_humongous_allocation);
901       if (result != NULL) {
902         assert(succeeded, "only way to get back a non-NULL result");
903         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
904                              Thread::current()->name(), p2i(result));
905         return result;
906       }
907 
908       if (succeeded) {
909         // We successfully scheduled a collection which failed to allocate. No
910         // point in trying to allocate further. We'll just return NULL.
911         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
912                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
913         return NULL;
914       }
915       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
916                            Thread::current()->name(), word_size);
917     } else {
918       // Failed to schedule a collection.
919       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
920         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
921                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
922         return NULL;
923       }
924       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
925       // The GCLocker is either active or the GCLocker initiated
926       // GC has not yet been performed. Stall until it is and
927       // then retry the allocation.
928       GCLocker::stall_until_clear();
929       gclocker_retry_count += 1;
930     }
931 
932 
933     // We can reach here if we were unsuccessful in scheduling a
934     // collection (because another thread beat us to it) or if we were
935     // stalled due to the GC locker. In either can we should retry the
936     // allocation attempt in case another thread successfully
937     // performed a collection and reclaimed enough space.
938     // Humongous object allocation always needs a lock, so we wait for the retry
939     // in the next iteration of the loop, unlike for the regular iteration case.
940     // Give a warning if we seem to be looping forever.
941 
942     if ((QueuedAllocationWarningCount > 0) &&
943         (try_count % QueuedAllocationWarningCount == 0)) {
944       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
945                              Thread::current()->name(), try_count, word_size);
946     }
947   }
948 
949   ShouldNotReachHere();
950   return NULL;
951 }
952 
953 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
954                                                            bool expect_null_mutator_alloc_region) {
955   assert_at_safepoint_on_vm_thread();
956   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
957          "the current alloc region was unexpectedly found to be non-NULL");
958 
959   if (!is_humongous(word_size)) {
960     return _allocator->attempt_allocation_locked(word_size);
961   } else {
962     HeapWord* result = humongous_obj_allocate(word_size);
963     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
964       collector_state()->set_initiate_conc_mark_if_possible(true);
965     }
966     return result;
967   }
968 
969   ShouldNotReachHere();
970 }
971 
972 class PostCompactionPrinterClosure: public HeapRegionClosure {
973 private:
974   G1HRPrinter* _hr_printer;
975 public:
976   bool do_heap_region(HeapRegion* hr) {
977     assert(!hr->is_young(), "not expecting to find young regions");
978     _hr_printer->post_compaction(hr);
979     return false;
980   }
981 
982   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
983     : _hr_printer(hr_printer) { }
984 };
985 
986 void G1CollectedHeap::print_hrm_post_compaction() {
987   if (_hr_printer.is_active()) {
988     PostCompactionPrinterClosure cl(hr_printer());
989     heap_region_iterate(&cl);
990   }
991 }
992 
993 void G1CollectedHeap::abort_concurrent_cycle() {
994   // If we start the compaction before the CM threads finish
995   // scanning the root regions we might trip them over as we'll
996   // be moving objects / updating references. So let's wait until
997   // they are done. By telling them to abort, they should complete
998   // early.
999   _cm->root_regions()->abort();
1000   _cm->root_regions()->wait_until_scan_finished();
1001 
1002   // Disable discovery and empty the discovered lists
1003   // for the CM ref processor.
1004   _ref_processor_cm->disable_discovery();
1005   _ref_processor_cm->abandon_partial_discovery();
1006   _ref_processor_cm->verify_no_references_recorded();
1007 
1008   // Abandon current iterations of concurrent marking and concurrent
1009   // refinement, if any are in progress.
1010   concurrent_mark()->concurrent_cycle_abort();
1011 }
1012 
1013 void G1CollectedHeap::prepare_heap_for_full_collection() {
1014   // Make sure we'll choose a new allocation region afterwards.
1015   _allocator->release_mutator_alloc_region();
1016   _allocator->abandon_gc_alloc_regions();
1017   g1_rem_set()->cleanupHRRS();
1018 
1019   // We may have added regions to the current incremental collection
1020   // set between the last GC or pause and now. We need to clear the
1021   // incremental collection set and then start rebuilding it afresh
1022   // after this full GC.
1023   abandon_collection_set(collection_set());
1024 
1025   tear_down_region_sets(false /* free_list_only */);
1026 }
1027 
1028 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1029   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1030   assert(used() == recalculate_used(), "Should be equal");
1031   _verifier->verify_region_sets_optional();
1032   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1033   _verifier->check_bitmaps("Full GC Start");
1034 }
1035 
1036 void G1CollectedHeap::prepare_heap_for_mutators() {
1037   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1038   ClassLoaderDataGraph::purge();
1039   MetaspaceUtils::verify_metrics();
1040 
1041   // Prepare heap for normal collections.
1042   assert(num_free_regions() == 0, "we should not have added any free regions");
1043   rebuild_region_sets(false /* free_list_only */);
1044   abort_refinement();
1045   resize_if_necessary_after_full_collection();
1046 
1047   // Rebuild the strong code root lists for each region
1048   rebuild_strong_code_roots();
1049 
1050   // Start a new incremental collection set for the next pause
1051   start_new_collection_set();
1052 
1053   _allocator->init_mutator_alloc_region();
1054 
1055   // Post collection state updates.
1056   MetaspaceGC::compute_new_size();
1057 }
1058 
1059 void G1CollectedHeap::abort_refinement() {
1060   if (_hot_card_cache->use_cache()) {
1061     _hot_card_cache->reset_hot_cache();
1062   }
1063 
1064   // Discard all remembered set updates.
1065   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1066   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1067 }
1068 
1069 void G1CollectedHeap::verify_after_full_collection() {
1070   _hrm.verify_optional();
1071   _verifier->verify_region_sets_optional();
1072   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1073   // Clear the previous marking bitmap, if needed for bitmap verification.
1074   // Note we cannot do this when we clear the next marking bitmap in
1075   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1076   // objects marked during a full GC against the previous bitmap.
1077   // But we need to clear it before calling check_bitmaps below since
1078   // the full GC has compacted objects and updated TAMS but not updated
1079   // the prev bitmap.
1080   if (G1VerifyBitmaps) {
1081     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1082     _cm->clear_prev_bitmap(workers());
1083   }
1084   _verifier->check_bitmaps("Full GC End");
1085 
1086   // At this point there should be no regions in the
1087   // entire heap tagged as young.
1088   assert(check_young_list_empty(), "young list should be empty at this point");
1089 
1090   // Note: since we've just done a full GC, concurrent
1091   // marking is no longer active. Therefore we need not
1092   // re-enable reference discovery for the CM ref processor.
1093   // That will be done at the start of the next marking cycle.
1094   // We also know that the STW processor should no longer
1095   // discover any new references.
1096   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1097   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1098   _ref_processor_stw->verify_no_references_recorded();
1099   _ref_processor_cm->verify_no_references_recorded();
1100 }
1101 
1102 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1103   // Post collection logging.
1104   // We should do this after we potentially resize the heap so
1105   // that all the COMMIT / UNCOMMIT events are generated before
1106   // the compaction events.
1107   print_hrm_post_compaction();
1108   heap_transition->print();
1109   print_heap_after_gc();
1110   print_heap_regions();
1111 #ifdef TRACESPINNING
1112   ParallelTaskTerminator::print_termination_counts();
1113 #endif
1114 }
1115 
1116 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1117                                          bool clear_all_soft_refs) {
1118   assert_at_safepoint_on_vm_thread();
1119 
1120   if (GCLocker::check_active_before_gc()) {
1121     // Full GC was not completed.
1122     return false;
1123   }
1124 
1125   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1126       soft_ref_policy()->should_clear_all_soft_refs();
1127 
1128   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1129   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1130 
1131   collector.prepare_collection();
1132   collector.collect();
1133   collector.complete_collection();
1134 
1135   // Full collection was successfully completed.
1136   return true;
1137 }
1138 
1139 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1140   // Currently, there is no facility in the do_full_collection(bool) API to notify
1141   // the caller that the collection did not succeed (e.g., because it was locked
1142   // out by the GC locker). So, right now, we'll ignore the return value.
1143   bool dummy = do_full_collection(true,                /* explicit_gc */
1144                                   clear_all_soft_refs);
1145 }
1146 
1147 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1148   // Capacity, free and used after the GC counted as full regions to
1149   // include the waste in the following calculations.
1150   const size_t capacity_after_gc = capacity();
1151   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1152 
1153   // This is enforced in arguments.cpp.
1154   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1155          "otherwise the code below doesn't make sense");
1156 
1157   // We don't have floating point command-line arguments
1158   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1159   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1160   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1161   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1162 
1163   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1164   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1165 
1166   // We have to be careful here as these two calculations can overflow
1167   // 32-bit size_t's.
1168   double used_after_gc_d = (double) used_after_gc;
1169   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1170   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1171 
1172   // Let's make sure that they are both under the max heap size, which
1173   // by default will make them fit into a size_t.
1174   double desired_capacity_upper_bound = (double) max_heap_size;
1175   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1176                                     desired_capacity_upper_bound);
1177   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1178                                     desired_capacity_upper_bound);
1179 
1180   // We can now safely turn them into size_t's.
1181   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1182   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1183 
1184   // This assert only makes sense here, before we adjust them
1185   // with respect to the min and max heap size.
1186   assert(minimum_desired_capacity <= maximum_desired_capacity,
1187          "minimum_desired_capacity = " SIZE_FORMAT ", "
1188          "maximum_desired_capacity = " SIZE_FORMAT,
1189          minimum_desired_capacity, maximum_desired_capacity);
1190 
1191   // Should not be greater than the heap max size. No need to adjust
1192   // it with respect to the heap min size as it's a lower bound (i.e.,
1193   // we'll try to make the capacity larger than it, not smaller).
1194   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1195   // Should not be less than the heap min size. No need to adjust it
1196   // with respect to the heap max size as it's an upper bound (i.e.,
1197   // we'll try to make the capacity smaller than it, not greater).
1198   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1199 
1200   if (capacity_after_gc < minimum_desired_capacity) {
1201     // Don't expand unless it's significant
1202     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1203 
1204     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1205                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1206                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1207                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1208 
1209     expand(expand_bytes, _workers);
1210 
1211     // No expansion, now see if we want to shrink
1212   } else if (capacity_after_gc > maximum_desired_capacity) {
1213     // Capacity too large, compute shrinking size
1214     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1215 
1216     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1217                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1218                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1219                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1220 
1221     shrink(shrink_bytes);
1222   }
1223 }
1224 
1225 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1226                                                             bool do_gc,
1227                                                             bool clear_all_soft_refs,
1228                                                             bool expect_null_mutator_alloc_region,
1229                                                             bool* gc_succeeded) {
1230   *gc_succeeded = true;
1231   // Let's attempt the allocation first.
1232   HeapWord* result =
1233     attempt_allocation_at_safepoint(word_size,
1234                                     expect_null_mutator_alloc_region);
1235   if (result != NULL) {
1236     return result;
1237   }
1238 
1239   // In a G1 heap, we're supposed to keep allocation from failing by
1240   // incremental pauses.  Therefore, at least for now, we'll favor
1241   // expansion over collection.  (This might change in the future if we can
1242   // do something smarter than full collection to satisfy a failed alloc.)
1243   result = expand_and_allocate(word_size);
1244   if (result != NULL) {
1245     return result;
1246   }
1247 
1248   if (do_gc) {
1249     // Expansion didn't work, we'll try to do a Full GC.
1250     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1251                                        clear_all_soft_refs);
1252   }
1253 
1254   return NULL;
1255 }
1256 
1257 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1258                                                      bool* succeeded) {
1259   assert_at_safepoint_on_vm_thread();
1260 
1261   // Attempts to allocate followed by Full GC.
1262   HeapWord* result =
1263     satisfy_failed_allocation_helper(word_size,
1264                                      true,  /* do_gc */
1265                                      false, /* clear_all_soft_refs */
1266                                      false, /* expect_null_mutator_alloc_region */
1267                                      succeeded);
1268 
1269   if (result != NULL || !*succeeded) {
1270     return result;
1271   }
1272 
1273   // Attempts to allocate followed by Full GC that will collect all soft references.
1274   result = satisfy_failed_allocation_helper(word_size,
1275                                             true, /* do_gc */
1276                                             true, /* clear_all_soft_refs */
1277                                             true, /* expect_null_mutator_alloc_region */
1278                                             succeeded);
1279 
1280   if (result != NULL || !*succeeded) {
1281     return result;
1282   }
1283 
1284   // Attempts to allocate, no GC
1285   result = satisfy_failed_allocation_helper(word_size,
1286                                             false, /* do_gc */
1287                                             false, /* clear_all_soft_refs */
1288                                             true,  /* expect_null_mutator_alloc_region */
1289                                             succeeded);
1290 
1291   if (result != NULL) {
1292     return result;
1293   }
1294 
1295   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1296          "Flag should have been handled and cleared prior to this point");
1297 
1298   // What else?  We might try synchronous finalization later.  If the total
1299   // space available is large enough for the allocation, then a more
1300   // complete compaction phase than we've tried so far might be
1301   // appropriate.
1302   return NULL;
1303 }
1304 
1305 // Attempting to expand the heap sufficiently
1306 // to support an allocation of the given "word_size".  If
1307 // successful, perform the allocation and return the address of the
1308 // allocated block, or else "NULL".
1309 
1310 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1311   assert_at_safepoint_on_vm_thread();
1312 
1313   _verifier->verify_region_sets_optional();
1314 
1315   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1316   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1317                             word_size * HeapWordSize);
1318 
1319 
1320   if (expand(expand_bytes, _workers)) {
1321     _hrm.verify_optional();
1322     _verifier->verify_region_sets_optional();
1323     return attempt_allocation_at_safepoint(word_size,
1324                                            false /* expect_null_mutator_alloc_region */);
1325   }
1326   return NULL;
1327 }
1328 
1329 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1330   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1331   aligned_expand_bytes = align_up(aligned_expand_bytes,
1332                                        HeapRegion::GrainBytes);
1333 
1334   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT 
1335                             expand_bytes, aligned_expand_bytes);
1336 
1337   if (is_maximal_no_gc()) {
1338     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1339     return false;
1340   }
1341 
1342   double expand_heap_start_time_sec = os::elapsedTime();
1343   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1344   assert(regions_to_expand > 0, "Must expand by at least one region");
1345 
1346   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1347   if (expand_time_ms != NULL) {
1348     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1349   }
1350 
1351   if (expanded_by > 0) {
1352     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1353     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1354     g1_policy()->record_new_heap_size(num_regions());
1355   } else {
1356     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1357 
1358     // The expansion of the virtual storage space was unsuccessful.
1359     // Let's see if it was because we ran out of swap.
1360     if (G1ExitOnExpansionFailure &&
1361         _hrm.available() >= regions_to_expand) {
1362       // We had head room...
1363       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1364     }
1365   }
1366   return regions_to_expand > 0;
1367 }
1368 
1369 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1370   size_t aligned_shrink_bytes =
1371     ReservedSpace::page_align_size_down(shrink_bytes);
1372   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1373                                          HeapRegion::GrainBytes);
1374   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1375 
1376   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1377   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1378 
1379 
1380   log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE
1381                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1382   if (num_regions_removed > 0) {
1383     g1_policy()->record_new_heap_size(num_regions());
1384   } else {
1385     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1386   }
1387 }
1388 
1389 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1390   _verifier->verify_region_sets_optional();
1391 
1392   // We should only reach here at the end of a Full GC which means we
1393   // should not not be holding to any GC alloc regions. The method
1394   // below will make sure of that and do any remaining clean up.
1395   _allocator->abandon_gc_alloc_regions();
1396 
1397   // Instead of tearing down / rebuilding the free lists here, we
1398   // could instead use the remove_all_pending() method on free_list to
1399   // remove only the ones that we need to remove.
1400   tear_down_region_sets(true /* free_list_only */);
1401   shrink_helper(shrink_bytes);
1402   rebuild_region_sets(true /* free_list_only */);
1403 
1404   _hrm.verify_optional();
1405   _verifier->verify_region_sets_optional();
1406 }
1407 
1408 class OldRegionSetChecker : public HeapRegionSetChecker {
1409 public:
1410   void check_mt_safety() {
1411     // Master Old Set MT safety protocol:
1412     // (a) If we're at a safepoint, operations on the master old set
1413     // should be invoked:
1414     // - by the VM thread (which will serialize them), or
1415     // - by the GC workers while holding the FreeList_lock, if we're
1416     //   at a safepoint for an evacuation pause (this lock is taken
1417     //   anyway when an GC alloc region is retired so that a new one
1418     //   is allocated from the free list), or
1419     // - by the GC workers while holding the OldSets_lock, if we're at a
1420     //   safepoint for a cleanup pause.
1421     // (b) If we're not at a safepoint, operations on the master old set
1422     // should be invoked while holding the Heap_lock.
1423 
1424     if (SafepointSynchronize::is_at_safepoint()) {
1425       guarantee(Thread::current()->is_VM_thread() ||
1426                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1427                 "master old set MT safety protocol at a safepoint");
1428     } else {
1429       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1430     }
1431   }
1432   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1433   const char* get_description() { return "Old Regions"; }
1434 };
1435 
1436 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1437 public:
1438   void check_mt_safety() {
1439     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1440               "May only change archive regions during initialization or safepoint.");
1441   }
1442   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1443   const char* get_description() { return "Archive Regions"; }
1444 };
1445 
1446 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1447 public:
1448   void check_mt_safety() {
1449     // Humongous Set MT safety protocol:
1450     // (a) If we're at a safepoint, operations on the master humongous
1451     // set should be invoked by either the VM thread (which will
1452     // serialize them) or by the GC workers while holding the
1453     // OldSets_lock.
1454     // (b) If we're not at a safepoint, operations on the master
1455     // humongous set should be invoked while holding the Heap_lock.
1456 
1457     if (SafepointSynchronize::is_at_safepoint()) {
1458       guarantee(Thread::current()->is_VM_thread() ||
1459                 OldSets_lock->owned_by_self(),
1460                 "master humongous set MT safety protocol at a safepoint");
1461     } else {
1462       guarantee(Heap_lock->owned_by_self(),
1463                 "master humongous set MT safety protocol outside a safepoint");
1464     }
1465   }
1466   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1467   const char* get_description() { return "Humongous Regions"; }
1468 };
1469 
1470 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1471   CollectedHeap(),
1472   _young_gen_sampling_thread(NULL),
1473   _workers(NULL),
1474   _collector_policy(collector_policy),
1475   _card_table(NULL),
1476   _soft_ref_policy(),
1477   _old_set("Old Region Set", new OldRegionSetChecker()),
1478   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1479   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1480   _bot(NULL),
1481   _listener(),
1482   _hrm(),
1483   _allocator(NULL),
1484   _verifier(NULL),
1485   _summary_bytes_used(0),
1486   _archive_allocator(NULL),
1487   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1488   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1489   _expand_heap_after_alloc_failure(true),
1490   _g1mm(NULL),
1491   _humongous_reclaim_candidates(),
1492   _has_humongous_reclaim_candidates(false),
1493   _hr_printer(),
1494   _collector_state(),
1495   _old_marking_cycles_started(0),
1496   _old_marking_cycles_completed(0),
1497   _eden(),
1498   _survivor(),
1499   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1500   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1501   _g1_policy(new G1Policy(_gc_timer_stw)),
1502   _heap_sizing_policy(NULL),
1503   _collection_set(this, _g1_policy),
1504   _hot_card_cache(NULL),
1505   _g1_rem_set(NULL),
1506   _dirty_card_queue_set(false),
1507   _cm(NULL),
1508   _cm_thread(NULL),
1509   _cr(NULL),
1510   _task_queues(NULL),
1511   _evacuation_failed(false),
1512   _evacuation_failed_info_array(NULL),
1513   _preserved_marks_set(true /* in_c_heap */),
1514 #ifndef PRODUCT
1515   _evacuation_failure_alot_for_current_gc(false),
1516   _evacuation_failure_alot_gc_number(0),
1517   _evacuation_failure_alot_count(0),
1518 #endif
1519   _ref_processor_stw(NULL),
1520   _is_alive_closure_stw(this),
1521   _is_subject_to_discovery_stw(this),
1522   _ref_processor_cm(NULL),
1523   _is_alive_closure_cm(this),
1524   _is_subject_to_discovery_cm(this),
1525   _in_cset_fast_test() {
1526 
1527   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1528                           true /* are_GC_task_threads */,
1529                           false /* are_ConcurrentGC_threads */);
1530   _workers->initialize_workers();
1531   _verifier = new G1HeapVerifier(this);
1532 
1533   _allocator = new G1Allocator(this);
1534 
1535   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1536 
1537   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1538 
1539   // Override the default _filler_array_max_size so that no humongous filler
1540   // objects are created.
1541   _filler_array_max_size = _humongous_object_threshold_in_words;
1542 
1543   uint n_queues = ParallelGCThreads;
1544   _task_queues = new RefToScanQueueSet(n_queues);
1545 
1546   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1547 
1548   for (uint i = 0; i < n_queues; i++) {
1549     RefToScanQueue* q = new RefToScanQueue();
1550     q->initialize();
1551     _task_queues->register_queue(i, q);
1552     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1553   }
1554 
1555   // Initialize the G1EvacuationFailureALot counters and flags.
1556   NOT_PRODUCT(reset_evacuation_should_fail();)
1557 
1558   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1559 }
1560 
1561 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1562                                                                  size_t size,
1563                                                                  size_t translation_factor) {
1564   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1565   // Allocate a new reserved space, preferring to use large pages.
1566   ReservedSpace rs(size, preferred_page_size);
1567   G1RegionToSpaceMapper* result  =
1568     G1RegionToSpaceMapper::create_mapper(rs,
1569                                          size,
1570                                          rs.alignment(),
1571                                          HeapRegion::GrainBytes,
1572                                          translation_factor,
1573                                          mtGC);
1574 
1575   os::trace_page_sizes_for_requested_size(description,
1576                                           size,
1577                                           preferred_page_size,
1578                                           rs.alignment(),
1579                                           rs.base(),
1580                                           rs.size());
1581 
1582   return result;
1583 }
1584 
1585 jint G1CollectedHeap::initialize_concurrent_refinement() {
1586   jint ecode = JNI_OK;
1587   _cr = G1ConcurrentRefine::create(&ecode);
1588   return ecode;
1589 }
1590 
1591 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1592   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1593   if (_young_gen_sampling_thread->osthread() == NULL) {
1594     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1595     return JNI_ENOMEM;
1596   }
1597   return JNI_OK;
1598 }
1599 
1600 jint G1CollectedHeap::initialize() {
1601   os::enable_vtime();
1602 
1603   // Necessary to satisfy locking discipline assertions.
1604 
1605   MutexLocker x(Heap_lock);
1606 
1607   // While there are no constraints in the GC code that HeapWordSize
1608   // be any particular value, there are multiple other areas in the
1609   // system which believe this to be true (e.g. oop->object_size in some
1610   // cases incorrectly returns the size in wordSize units rather than
1611   // HeapWordSize).
1612   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1613 
1614   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1615   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1616   size_t heap_alignment = collector_policy()->heap_alignment();
1617 
1618   // Ensure that the sizes are properly aligned.
1619   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1620   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1621   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1622 
1623   // Reserve the maximum.
1624 
1625   // When compressed oops are enabled, the preferred heap base
1626   // is calculated by subtracting the requested size from the
1627   // 32Gb boundary and using the result as the base address for
1628   // heap reservation. If the requested size is not aligned to
1629   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1630   // into the ReservedHeapSpace constructor) then the actual
1631   // base of the reserved heap may end up differing from the
1632   // address that was requested (i.e. the preferred heap base).
1633   // If this happens then we could end up using a non-optimal
1634   // compressed oops mode.
1635 
1636   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1637                                                  heap_alignment);
1638 
1639   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1640 
1641   // Create the barrier set for the entire reserved region.
1642   G1CardTable* ct = new G1CardTable(reserved_region());
1643   ct->initialize();
1644   G1BarrierSet* bs = new G1BarrierSet(ct);
1645   bs->initialize();
1646   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1647   BarrierSet::set_barrier_set(bs);
1648   _card_table = ct;
1649 
1650   // Create the hot card cache.
1651   _hot_card_cache = new G1HotCardCache(this);
1652 
1653   // Carve out the G1 part of the heap.
1654   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1655   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1656   G1RegionToSpaceMapper* heap_storage =
1657     G1RegionToSpaceMapper::create_mapper(g1_rs,
1658                                          g1_rs.size(),
1659                                          page_size,
1660                                          HeapRegion::GrainBytes,
1661                                          1,
1662                                          mtJavaHeap);
1663   os::trace_page_sizes("Heap",
1664                        collector_policy()->min_heap_byte_size(),
1665                        max_byte_size,
1666                        page_size,
1667                        heap_rs.base(),
1668                        heap_rs.size());
1669   heap_storage->set_mapping_changed_listener(&_listener);
1670 
1671   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1672   G1RegionToSpaceMapper* bot_storage =
1673     create_aux_memory_mapper("Block Offset Table",
1674                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1675                              G1BlockOffsetTable::heap_map_factor());
1676 
1677   G1RegionToSpaceMapper* cardtable_storage =
1678     create_aux_memory_mapper("Card Table",
1679                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1680                              G1CardTable::heap_map_factor());
1681 
1682   G1RegionToSpaceMapper* card_counts_storage =
1683     create_aux_memory_mapper("Card Counts Table",
1684                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1685                              G1CardCounts::heap_map_factor());
1686 
1687   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1688   G1RegionToSpaceMapper* prev_bitmap_storage =
1689     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1690   G1RegionToSpaceMapper* next_bitmap_storage =
1691     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1692 
1693   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_stora
1694   _card_table->initialize(cardtable_storage);
1695   // Do later initialization work for concurrent refinement.
1696   _hot_card_cache->initialize(card_counts_storage);
1697 
1698   // 6843694 - ensure that the maximum region index can fit
1699   // in the remembered set structures.
1700   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1701   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1702 
1703   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1704   // start within the first card.
1705   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1706   // Also create a G1 rem set.
1707   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1708   _g1_rem_set->initialize(max_capacity(), max_regions());
1709 
1710   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1711   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1712   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1713             "too many cards per region");
1714 
1715   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1716 
1717   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1718 
1719   {
1720     HeapWord* start = _hrm.reserved().start();
1721     HeapWord* end = _hrm.reserved().end();
1722     size_t granularity = HeapRegion::GrainBytes;
1723 
1724     _in_cset_fast_test.initialize(start, end, granularity);
1725     _humongous_reclaim_candidates.initialize(start, end, granularity);
1726   }
1727 
1728   // Create the G1ConcurrentMark data structure and thread.
1729   // (Must do this late, so that "max_regions" is defined.)
1730   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1731   if (_cm == NULL || !_cm->completed_initialization()) {
1732     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1733     return JNI_ENOMEM;
1734   }
1735   _cm_thread = _cm->cm_thread();
1736 
1737   // Now expand into the initial heap size.
1738   if (!expand(init_byte_size, _workers)) {
1739     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1740     return JNI_ENOMEM;
1741   }
1742 
1743   // Perform any initialization actions delegated to the policy.
1744   g1_policy()->init(this, &_collection_set);
1745 
1746   G1BarrierSet::satb_mark_queue_set().initialize(this,
1747                                                  SATB_Q_CBL_mon,
1748                                                  SATB_Q_FL_lock,
1749                                                  G1SATBProcessCompletedThreshold,
1750                                                  G1SATBBufferEnqueueingThresholdPercent,
1751                                                  Shared_SATB_Q_lock);
1752 
1753   jint ecode = initialize_concurrent_refinement();
1754   if (ecode != JNI_OK) {
1755     return ecode;
1756   }
1757 
1758   ecode = initialize_young_gen_sampling_thread();
1759   if (ecode != JNI_OK) {
1760     return ecode;
1761   }
1762 
1763   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1764                                                   DirtyCardQ_FL_lock,
1765                                                   (int)concurrent_refine()->yellow_zone(),
1766                                                   (int)concurrent_refine()->red_zone(),
1767                                                   Shared_DirtyCardQ_lock,
1768                                                   NULL,  // fl_owner
1769                                                   true); // init_free_ids
1770 
1771   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1772                                     DirtyCardQ_FL_lock,
1773                                     -1, // never trigger processing
1774                                     -1, // no limit on length
1775                                     Shared_DirtyCardQ_lock,
1776                                     &G1BarrierSet::dirty_card_queue_set());
1777 
1778   // Here we allocate the dummy HeapRegion that is required by the
1779   // G1AllocRegion class.
1780   HeapRegion* dummy_region = _hrm.get_dummy_region();
1781 
1782   // We'll re-use the same region whether the alloc region will
1783   // require BOT updates or not and, if it doesn't, then a non-young
1784   // region will complain that it cannot support allocations without
1785   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1786   dummy_region->set_eden();
1787   // Make sure it's full.
1788   dummy_region->set_top(dummy_region->end());
1789   G1AllocRegion::setup(this, dummy_region);
1790 
1791   _allocator->init_mutator_alloc_region();
1792 
1793   // Do create of the monitoring and management support so that
1794   // values in the heap have been properly initialized.
1795   _g1mm = new G1MonitoringSupport(this);
1796 
1797   G1StringDedup::initialize();
1798 
1799   _preserved_marks_set.init(ParallelGCThreads);
1800 
1801   _collection_set.initialize(max_regions());
1802 
1803   return JNI_OK;
1804 }
1805 
1806 void G1CollectedHeap::stop() {
1807   // Stop all concurrent threads. We do this to make sure these threads
1808   // do not continue to execute and access resources (e.g. logging)
1809   // that are destroyed during shutdown.
1810   _cr->stop();
1811   _young_gen_sampling_thread->stop();
1812   _cm_thread->stop();
1813   if (G1StringDedup::is_enabled()) {
1814     G1StringDedup::stop();
1815   }
1816 }
1817 
1818 void G1CollectedHeap::safepoint_synchronize_begin() {
1819   SuspendibleThreadSet::synchronize();
1820 }
1821 
1822 void G1CollectedHeap::safepoint_synchronize_end() {
1823   SuspendibleThreadSet::desynchronize();
1824 }
1825 
1826 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1827   return HeapRegion::max_region_size();
1828 }
1829 
1830 void G1CollectedHeap::post_initialize() {
1831   CollectedHeap::post_initialize();
1832   ref_processing_init();
1833 }
1834 
1835 void G1CollectedHeap::ref_processing_init() {
1836   // Reference processing in G1 currently works as follows:
1837   //
1838   // * There are two reference processor instances. One is
1839   //   used to record and process discovered references
1840   //   during concurrent marking; the other is used to
1841   //   record and process references during STW pauses
1842   //   (both full and incremental).
1843   // * Both ref processors need to 'span' the entire heap as
1844   //   the regions in the collection set may be dotted around.
1845   //
1846   // * For the concurrent marking ref processor:
1847   //   * Reference discovery is enabled at initial marking.
1848   //   * Reference discovery is disabled and the discovered
1849   //     references processed etc during remarking.
1850   //   * Reference discovery is MT (see below).
1851   //   * Reference discovery requires a barrier (see below).
1852   //   * Reference processing may or may not be MT
1853   //     (depending on the value of ParallelRefProcEnabled
1854   //     and ParallelGCThreads).
1855   //   * A full GC disables reference discovery by the CM
1856   //     ref processor and abandons any entries on it's
1857   //     discovered lists.
1858   //
1859   // * For the STW processor:
1860   //   * Non MT discovery is enabled at the start of a full GC.
1861   //   * Processing and enqueueing during a full GC is non-MT.
1862   //   * During a full GC, references are processed after marking.
1863   //
1864   //   * Discovery (may or may not be MT) is enabled at the start
1865   //     of an incremental evacuation pause.
1866   //   * References are processed near the end of a STW evacuation pause.
1867   //   * For both types of GC:
1868   //     * Discovery is atomic - i.e. not concurrent.
1869   //     * Reference discovery will not need a barrier.
1870 
1871   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1872 
1873   // Concurrent Mark ref processor
1874   _ref_processor_cm =
1875     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1876                            mt_processing,                                  // mt processing
1877                            ParallelGCThreads,                              // degree of mt processing
1878                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1879                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1880                            false,                                          // Reference discovery is not atomic
1881                            &_is_alive_closure_cm,                          // is alive closure
1882                            true);                                          // allow changes to number of processing threads
1883 
1884   // STW ref processor
1885   _ref_processor_stw =
1886     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1887                            mt_processing,                        // mt processing
1888                            ParallelGCThreads,                    // degree of mt processing
1889                            (ParallelGCThreads > 1),              // mt discovery
1890                            ParallelGCThreads,                    // degree of mt discovery
1891                            true,                                 // Reference discovery is atomic
1892                            &_is_alive_closure_stw,               // is alive closure
1893                            true);                                // allow changes to number of processing threads
1894 }
1895 
1896 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1897   return _collector_policy;
1898 }
1899 
1900 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1901   return &_soft_ref_policy;
1902 }
1903 
1904 size_t G1CollectedHeap::capacity() const {
1905   return _hrm.length() * HeapRegion::GrainBytes;
1906 }
1907 
1908 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1909   return _hrm.total_free_bytes();
1910 }
1911 
1912 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1913   _hot_card_cache->drain(cl, worker_i);
1914 }
1915 
1916 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1917   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1918   size_t n_completed_buffers = 0;
1919   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1920     n_completed_buffers++;
1921   }
1922   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTim
1923   dcqs.clear_n_completed_buffers();
1924   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1925 }
1926 
1927 // Computes the sum of the storage used by the various regions.
1928 size_t G1CollectedHeap::used() const {
1929   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1930   if (_archive_allocator != NULL) {
1931     result += _archive_allocator->used();
1932   }
1933   return result;
1934 }
1935 
1936 size_t G1CollectedHeap::used_unlocked() const {
1937   return _summary_bytes_used;
1938 }
1939 
1940 class SumUsedClosure: public HeapRegionClosure {
1941   size_t _used;
1942 public:
1943   SumUsedClosure() : _used(0) {}
1944   bool do_heap_region(HeapRegion* r) {
1945     _used += r->used();
1946     return false;
1947   }
1948   size_t result() { return _used; }
1949 };
1950 
1951 size_t G1CollectedHeap::recalculate_used() const {
1952   double recalculate_used_start = os::elapsedTime();
1953 
1954   SumUsedClosure blk;
1955   heap_region_iterate(&blk);
1956 
1957   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1958   return blk.result();
1959 }
1960 
1961 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1962   switch (cause) {
1963     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1964     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1965     case GCCause::_wb_conc_mark:                        return true;
1966     default :                                           return false;
1967   }
1968 }
1969 
1970 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1971   switch (cause) {
1972     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
1973     case GCCause::_g1_humongous_allocation: return true;
1974     default:                                return is_user_requested_concurrent_full_gc(cause);
1975   }
1976 }
1977 
1978 #ifndef PRODUCT
1979 void G1CollectedHeap::allocate_dummy_regions() {
1980   // Let's fill up most of the region
1981   size_t word_size = HeapRegion::GrainWords - 1024;
1982   // And as a result the region we'll allocate will be humongous.
1983   guarantee(is_humongous(word_size), "sanity");
1984 
1985   // _filler_array_max_size is set to humongous object threshold
1986   // but temporarily change it to use CollectedHeap::fill_with_object().
1987   SizeTFlagSetting fs(_filler_array_max_size, word_size);
1988 
1989   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1990     // Let's use the existing mechanism for the allocation
1991     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1992     if (dummy_obj != NULL) {
1993       MemRegion mr(dummy_obj, word_size);
1994       CollectedHeap::fill_with_object(mr);
1995     } else {
1996       // If we can't allocate once, we probably cannot allocate
1997       // again. Let's get out of the loop.
1998       break;
1999     }
2000   }
2001 }
2002 #endif // !PRODUCT
2003 
2004 void G1CollectedHeap::increment_old_marking_cycles_started() {
2005   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2006          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2007          "Wrong marking cycle count (started: %d, completed: %d)",
2008          _old_marking_cycles_started, _old_marking_cycles_completed);
2009 
2010   _old_marking_cycles_started++;
2011 }
2012 
2013 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2014   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2015 
2016   // We assume that if concurrent == true, then the caller is a
2017   // concurrent thread that was joined the Suspendible Thread
2018   // Set. If there's ever a cheap way to check this, we should add an
2019   // assert here.
2020 
2021   // Given that this method is called at the end of a Full GC or of a
2022   // concurrent cycle, and those can be nested (i.e., a Full GC can
2023   // interrupt a concurrent cycle), the number of full collections
2024   // completed should be either one (in the case where there was no
2025   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2026   // behind the number of full collections started.
2027 
2028   // This is the case for the inner caller, i.e. a Full GC.
2029   assert(concurrent ||
2030          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2031          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2032          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2033          "is inconsistent with _old_marking_cycles_completed = %u",
2034          _old_marking_cycles_started, _old_marking_cycles_completed);
2035 
2036   // This is the case for the outer caller, i.e. the concurrent cycle.
2037   assert(!concurrent ||
2038          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2039          "for outer caller (concurrent cycle): "
2040          "_old_marking_cycles_started = %u "
2041          "is inconsistent with _old_marking_cycles_completed = %u",
2042          _old_marking_cycles_started, _old_marking_cycles_completed);
2043 
2044   _old_marking_cycles_completed += 1;
2045 
2046   // We need to clear the "in_progress" flag in the CM thread before
2047   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2048   // is set) so that if a waiter requests another System.gc() it doesn't
2049   // incorrectly see that a marking cycle is still in progress.
2050   if (concurrent) {
2051     _cm_thread->set_idle();
2052   }
2053 
2054   // This notify_all() will ensure that a thread that called
2055   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2056   // and it's waiting for a full GC to finish will be woken up. It is
2057   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2058   FullGCCount_lock->notify_all();
2059 }
2060 
2061 void G1CollectedHeap::collect(GCCause::Cause cause) {
2062   assert_heap_not_locked();
2063 
2064   uint gc_count_before;
2065   uint old_marking_count_before;
2066   uint full_gc_count_before;
2067   bool retry_gc;
2068 
2069   do {
2070     retry_gc = false;
2071 
2072     {
2073       MutexLocker ml(Heap_lock);
2074 
2075       // Read the GC count while holding the Heap_lock
2076       gc_count_before = total_collections();
2077       full_gc_count_before = total_full_collections();
2078       old_marking_count_before = _old_marking_cycles_started;
2079     }
2080 
2081     if (should_do_concurrent_full_gc(cause)) {
2082       // Schedule an initial-mark evacuation pause that will start a
2083       // concurrent cycle. We're setting word_size to 0 which means that
2084       // we are not requesting a post-GC allocation.
2085       VM_G1CollectForAllocation op(0,     /* word_size */
2086                                    gc_count_before,
2087                                    cause,
2088                                    true,  /* should_initiate_conc_mark */
2089                                    g1_policy()->max_pause_time_ms());
2090       VMThread::execute(&op);
2091       if (!op.pause_succeeded()) {
2092         if (old_marking_count_before == _old_marking_cycles_started) {
2093           retry_gc = op.should_retry_gc();
2094         } else {
2095           // A Full GC happened while we were trying to schedule the
2096           // initial-mark GC. No point in starting a new cycle given
2097           // that the whole heap was collected anyway.
2098         }
2099 
2100         if (retry_gc) {
2101           if (GCLocker::is_active_and_needs_gc()) {
2102             GCLocker::stall_until_clear();
2103           }
2104         }
2105       }
2106     } else {
2107       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2108           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2109 
2110         // Schedule a standard evacuation pause. We're setting word_size
2111         // to 0 which means that we are not requesting a post-GC allocation.
2112         VM_G1CollectForAllocation op(0,     /* word_size */
2113                                      gc_count_before,
2114                                      cause,
2115                                      false, /* should_initiate_conc_mark */
2116                                      g1_policy()->max_pause_time_ms());
2117         VMThread::execute(&op);
2118       } else {
2119         // Schedule a Full GC.
2120         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2121         VMThread::execute(&op);
2122       }
2123     }
2124   } while (retry_gc);
2125 }
2126 
2127 bool G1CollectedHeap::is_in(const void* p) const {
2128   if (_hrm.reserved().contains(p)) {
2129     // Given that we know that p is in the reserved space,
2130     // heap_region_containing() should successfully
2131     // return the containing region.
2132     HeapRegion* hr = heap_region_containing(p);
2133     return hr->is_in(p);
2134   } else {
2135     return false;
2136   }
2137 }
2138 
2139 #ifdef ASSERT
2140 bool G1CollectedHeap::is_in_exact(const void* p) const {
2141   bool contains = reserved_region().contains(p);
2142   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2143   if (contains && available) {
2144     return true;
2145   } else {
2146     return false;
2147   }
2148 }
2149 #endif
2150 
2151 // Iteration functions.
2152 
2153 // Iterates an ObjectClosure over all objects within a HeapRegion.
2154 
2155 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2156   ObjectClosure* _cl;
2157 public:
2158   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2159   bool do_heap_region(HeapRegion* r) {
2160     if (!r->is_continues_humongous()) {
2161       r->object_iterate(_cl);
2162     }
2163     return false;
2164   }
2165 };
2166 
2167 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2168   IterateObjectClosureRegionClosure blk(cl);
2169   heap_region_iterate(&blk);
2170 }
2171 
2172 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2173   _hrm.iterate(cl);
2174 }
2175 
2176 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2177                                                                  HeapRegionClaimer *hrclaimer,
2178                                                                  uint worker_id) const {
2179   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2180 }
2181 
2182 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2183                                                          HeapRegionClaimer *hrclaimer) const {
2184   _hrm.par_iterate(cl, hrclaimer, 0);
2185 }
2186 
2187 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2188   _collection_set.iterate(cl);
2189 }
2190 
2191 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2192   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2193 }
2194 
2195 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2196   HeapRegion* hr = heap_region_containing(addr);
2197   return hr->block_start(addr);
2198 }
2199 
2200 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2201   HeapRegion* hr = heap_region_containing(addr);
2202   return hr->block_size(addr);
2203 }
2204 
2205 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2206   HeapRegion* hr = heap_region_containing(addr);
2207   return hr->block_is_obj(addr);
2208 }
2209 
2210 bool G1CollectedHeap::supports_tlab_allocation() const {
2211   return true;
2212 }
2213 
2214 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2215   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2216 }
2217 
2218 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2219   return _eden.length() * HeapRegion::GrainBytes;
2220 }
2221 
2222 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2223 // must be equal to the humongous object limit.
2224 size_t G1CollectedHeap::max_tlab_size() const {
2225   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2226 }
2227 
2228 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2229   return _allocator->unsafe_max_tlab_alloc();
2230 }
2231 
2232 size_t G1CollectedHeap::max_capacity() const {
2233   return _hrm.reserved().byte_size();
2234 }
2235 
2236 jlong G1CollectedHeap::millis_since_last_gc() {
2237   // See the notes in GenCollectedHeap::millis_since_last_gc()
2238   // for more information about the implementation.
2239   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2240     _g1_policy->collection_pause_end_millis();
2241   if (ret_val < 0) {
2242     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2243       ". returning zero instead.", ret_val);
2244     return 0;
2245   }
2246   return ret_val;
2247 }
2248 
2249 void G1CollectedHeap::deduplicate_string(oop str) {
2250   assert(java_lang_String::is_instance(str), "invariant");
2251 
2252   if (G1StringDedup::is_enabled()) {
2253     G1StringDedup::deduplicate(str);
2254   }
2255 }
2256 
2257 void G1CollectedHeap::prepare_for_verify() {
2258   _verifier->prepare_for_verify();
2259 }
2260 
2261 void G1CollectedHeap::verify(VerifyOption vo) {
2262   _verifier->verify(vo);
2263 }
2264 
2265 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2266   return true;
2267 }
2268 
2269 const char* const* G1CollectedHeap::concurrent_phases() const {
2270   return _cm_thread->concurrent_phases();
2271 }
2272 
2273 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2274   return _cm_thread->request_concurrent_phase(phase);
2275 }
2276 
2277 class PrintRegionClosure: public HeapRegionClosure {
2278   outputStream* _st;
2279 public:
2280   PrintRegionClosure(outputStream* st) : _st(st) {}
2281   bool do_heap_region(HeapRegion* r) {
2282     r->print_on(_st);
2283     return false;
2284   }
2285 };
2286 
2287 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2288                                        const HeapRegion* hr,
2289                                        const VerifyOption vo) const {
2290   switch (vo) {
2291   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2292   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2293   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2294   default:                            ShouldNotReachHere();
2295   }
2296   return false; // keep some compilers happy
2297 }
2298 
2299 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2300                                        const VerifyOption vo) const {
2301   switch (vo) {
2302   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2303   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2304   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2305   default:                            ShouldNotReachHere();
2306   }
2307   return false; // keep some compilers happy
2308 }
2309 
2310 void G1CollectedHeap::print_heap_regions() const {
2311   LogTarget(Trace, gc, heap, region) lt;
2312   if (lt.is_enabled()) {
2313     LogStream ls(lt);
2314     print_regions_on(&ls);
2315   }
2316 }
2317 
2318 void G1CollectedHeap::print_on(outputStream* st) const {
2319   st->print(" %-20s", "garbage-first heap");
2320   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2321             capacity()/K, used_unlocked()/K);
2322   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2323             p2i(_hrm.reserved().start()),
2324             p2i(_hrm.reserved().end()));
2325   st->cr();
2326   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2327   uint young_regions = young_regions_count();
2328   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2329             (size_t) young_regions * HeapRegion::GrainBytes / K);
2330   uint survivor_regions = survivor_regions_count();
2331   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2332             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2333   st->cr();
2334   MetaspaceUtils::print_on(st);
2335 }
2336 
2337 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2338   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2339                "HS=humongous(starts), HC=humongous(continues), "
2340                "CS=collection set, F=free, A=archive, "
2341                "TAMS=top-at-mark-start (previous, next)");
2342   PrintRegionClosure blk(st);
2343   heap_region_iterate(&blk);
2344 }
2345 
2346 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2347   print_on(st);
2348 
2349   // Print the per-region information.
2350   print_regions_on(st);
2351 }
2352 
2353 void G1CollectedHeap::print_on_error(outputStream* st) const {
2354   this->CollectedHeap::print_on_error(st);
2355 
2356   if (_cm != NULL) {
2357     st->cr();
2358     _cm->print_on_error(st);
2359   }
2360 }
2361 
2362 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2363   workers()->print_worker_threads_on(st);
2364   _cm_thread->print_on(st);
2365   st->cr();
2366   _cm->print_worker_threads_on(st);
2367   _cr->print_threads_on(st);
2368   _young_gen_sampling_thread->print_on(st);
2369   if (G1StringDedup::is_enabled()) {
2370     G1StringDedup::print_worker_threads_on(st);
2371   }
2372 }
2373 
2374 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2375   workers()->threads_do(tc);
2376   tc->do_thread(_cm_thread);
2377   _cm->threads_do(tc);
2378   _cr->threads_do(tc);
2379   tc->do_thread(_young_gen_sampling_thread);
2380   if (G1StringDedup::is_enabled()) {
2381     G1StringDedup::threads_do(tc);
2382   }
2383 }
2384 
2385 void G1CollectedHeap::print_tracing_info() const {
2386   g1_rem_set()->print_summary_info();
2387   concurrent_mark()->print_summary_info();
2388 }
2389 
2390 #ifndef PRODUCT
2391 // Helpful for debugging RSet issues.
2392 
2393 class PrintRSetsClosure : public HeapRegionClosure {
2394 private:
2395   const char* _msg;
2396   size_t _occupied_sum;
2397 
2398 public:
2399   bool do_heap_region(HeapRegion* r) {
2400     HeapRegionRemSet* hrrs = r->rem_set();
2401     size_t occupied = hrrs->occupied();
2402     _occupied_sum += occupied;
2403 
2404     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2405     if (occupied == 0) {
2406       tty->print_cr("  RSet is empty");
2407     } else {
2408       hrrs->print();
2409     }
2410     tty->print_cr("----------");
2411     return false;
2412   }
2413 
2414   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2415     tty->cr();
2416     tty->print_cr("========================================");
2417     tty->print_cr("%s", msg);
2418     tty->cr();
2419   }
2420 
2421   ~PrintRSetsClosure() {
2422     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2423     tty->print_cr("========================================");
2424     tty->cr();
2425   }
2426 };
2427 
2428 void G1CollectedHeap::print_cset_rsets() {
2429   PrintRSetsClosure cl("Printing CSet RSets");
2430   collection_set_iterate(&cl);
2431 }
2432 
2433 void G1CollectedHeap::print_all_rsets() {
2434   PrintRSetsClosure cl("Printing All RSets");;
2435   heap_region_iterate(&cl);
2436 }
2437 #endif // PRODUCT
2438 
2439 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2440 
2441   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2442   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2443   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2444 
2445   size_t eden_capacity_bytes =
2446     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2447 
2448   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2449   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2450                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2451 }
2452 
2453 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2454   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2455                        stats->unused(), stats->used(), stats->region_end_waste(),
2456                        stats->regions_filled(), stats->direct_allocated(),
2457                        stats->failure_used(), stats->failure_waste());
2458 }
2459 
2460 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2461   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2462   gc_tracer->report_gc_heap_summary(when, heap_summary);
2463 
2464   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2465   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2466 }
2467 
2468 G1CollectedHeap* G1CollectedHeap::heap() {
2469   CollectedHeap* heap = Universe::heap();
2470   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2471   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2472   return (G1CollectedHeap*)heap;
2473 }
2474 
2475 void G1CollectedHeap::gc_prologue(bool full) {
2476   // always_do_update_barrier = false;
2477   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2478 
2479   // This summary needs to be printed before incrementing total collections.
2480   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2481 
2482   // Update common counters.
2483   increment_total_collections(full /* full gc */);
2484   if (full) {
2485     increment_old_marking_cycles_started();
2486   }
2487 
2488   // Fill TLAB's and such
2489   double start = os::elapsedTime();
2490   accumulate_statistics_all_tlabs();
2491   ensure_parsability(true);
2492   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2493 }
2494 
2495 void G1CollectedHeap::gc_epilogue(bool full) {
2496   // Update common counters.
2497   if (full) {
2498     // Update the number of full collections that have been completed.
2499     increment_old_marking_cycles_completed(false /* concurrent */);
2500   }
2501 
2502   // We are at the end of the GC. Total collections has already been increased.
2503   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2504 
2505   // FIXME: what is this about?
2506   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2507   // is set.
2508 #if COMPILER2_OR_JVMCI
2509   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2510 #endif
2511   // always_do_update_barrier = true;
2512 
2513   double start = os::elapsedTime();
2514   resize_all_tlabs();
2515   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2516 
2517   MemoryService::track_memory_usage();
2518   // We have just completed a GC. Update the soft reference
2519   // policy with the new heap occupancy
2520   Universe::update_heap_info_at_gc();
2521 }
2522 
2523 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2524                                                uint gc_count_before,
2525                                                bool* succeeded,
2526                                                GCCause::Cause gc_cause) {
2527   assert_heap_not_locked_and_not_at_safepoint();
2528   VM_G1CollectForAllocation op(word_size,
2529                                gc_count_before,
2530                                gc_cause,
2531                                false, /* should_initiate_conc_mark */
2532                                g1_policy()->max_pause_time_ms());
2533   VMThread::execute(&op);
2534 
2535   HeapWord* result = op.result();
2536   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2537   assert(result == NULL || ret_succeeded,
2538          "the result should be NULL if the VM did not succeed");
2539   *succeeded = ret_succeeded;
2540 
2541   assert_heap_not_locked();
2542   return result;
2543 }
2544 
2545 void G1CollectedHeap::do_concurrent_mark() {
2546   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2547   if (!_cm_thread->in_progress()) {
2548     _cm_thread->set_started();
2549     CGC_lock->notify();
2550   }
2551 }
2552 
2553 size_t G1CollectedHeap::pending_card_num() {
2554   size_t extra_cards = 0;
2555   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2556     DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2557     extra_cards += dcq.size();
2558   }
2559   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2560   size_t buffer_size = dcqs.buffer_size();
2561   size_t buffer_num = dcqs.completed_buffers_num();
2562 
2563   return buffer_size * buffer_num + extra_cards;
2564 }
2565 
2566 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2567   // We don't nominate objects with many remembered set entries, on
2568   // the assumption that such objects are likely still live.
2569   HeapRegionRemSet* rem_set = r->rem_set();
2570 
2571   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2572          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2573          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2574 }
2575 
2576 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2577  private:
2578   size_t _total_humongous;
2579   size_t _candidate_humongous;
2580 
2581   DirtyCardQueue _dcq;
2582 
2583   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2584     assert(region->is_starts_humongous(), "Must start a humongous object");
2585 
2586     oop obj = oop(region->bottom());
2587 
2588     // Dead objects cannot be eager reclaim candidates. Due to class
2589     // unloading it is unsafe to query their classes so we return early.
2590     if (g1h->is_obj_dead(obj, region)) {
2591       return false;
2592     }
2593 
2594     // If we do not have a complete remembered set for the region, then we can
2595     // not be sure that we have all references to it.
2596     if (!region->rem_set()->is_complete()) {
2597       return false;
2598     }
2599     // Candidate selection must satisfy the following constraints
2600     // while concurrent marking is in progress:
2601     //
2602     // * In order to maintain SATB invariants, an object must not be
2603     // reclaimed if it was allocated before the start of marking and
2604     // has not had its references scanned.  Such an object must have
2605     // its references (including type metadata) scanned to ensure no
2606     // live objects are missed by the marking process.  Objects
2607     // allocated after the start of concurrent marking don't need to
2608     // be scanned.
2609     //
2610     // * An object must not be reclaimed if it is on the concurrent
2611     // mark stack.  Objects allocated after the start of concurrent
2612     // marking are never pushed on the mark stack.
2613     //
2614     // Nominating only objects allocated after the start of concurrent
2615     // marking is sufficient to meet both constraints.  This may miss
2616     // some objects that satisfy the constraints, but the marking data
2617     // structures don't support efficiently performing the needed
2618     // additional tests or scrubbing of the mark stack.
2619     //
2620     // However, we presently only nominate is_typeArray() objects.
2621     // A humongous object containing references induces remembered
2622     // set entries on other regions.  In order to reclaim such an
2623     // object, those remembered sets would need to be cleaned up.
2624     //
2625     // We also treat is_typeArray() objects specially, allowing them
2626     // to be reclaimed even if allocated before the start of
2627     // concurrent mark.  For this we rely on mark stack insertion to
2628     // exclude is_typeArray() objects, preventing reclaiming an object
2629     // that is in the mark stack.  We also rely on the metadata for
2630     // such objects to be built-in and so ensured to be kept live.
2631     // Frequent allocation and drop of large binary blobs is an
2632     // important use case for eager reclaim, and this special handling
2633     // may reduce needed headroom.
2634 
2635     return obj->is_typeArray() &&
2636            g1h->is_potential_eager_reclaim_candidate(region);
2637   }
2638 
2639  public:
2640   RegisterHumongousWithInCSetFastTestClosure()
2641   : _total_humongous(0),
2642     _candidate_humongous(0),
2643     _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2644   }
2645 
2646   virtual bool do_heap_region(HeapRegion* r) {
2647     if (!r->is_starts_humongous()) {
2648       return false;
2649     }
2650     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2651 
2652     bool is_candidate = humongous_region_is_candidate(g1h, r);
2653     uint rindex = r->hrm_index();
2654     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2655     if (is_candidate) {
2656       _candidate_humongous++;
2657       g1h->register_humongous_region_with_cset(rindex);
2658       // Is_candidate already filters out humongous object with large remembered sets.
2659       // If we have a humongous object with a few remembered sets, we simply flush these
2660       // remembered set entries into the DCQS. That will result in automatic
2661       // re-evaluation of their remembered set entries during the following evacuation
2662       // phase.
2663       if (!r->rem_set()->is_empty()) {
2664         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2665                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2666         G1CardTable* ct = g1h->card_table();
2667         HeapRegionRemSetIterator hrrs(r->rem_set());
2668         size_t card_index;
2669         while (hrrs.has_next(card_index)) {
2670           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2671           // The remembered set might contain references to already freed
2672           // regions. Filter out such entries to avoid failing card table
2673           // verification.
2674           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2675             if (*card_ptr != G1CardTable::dirty_card_val()) {
2676               *card_ptr = G1CardTable::dirty_card_val();
2677               _dcq.enqueue(card_ptr);
2678             }
2679           }
2680         }
2681         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2682                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2683                hrrs.n_yielded(), r->rem_set()->occupied());
2684         // We should only clear the card based remembered set here as we will not
2685         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2686         // (and probably never) we do not enter this path if there are other kind of
2687         // remembered sets for this region.
2688         r->rem_set()->clear_locked(true /* only_cardset */);
2689         // Clear_locked() above sets the state to Empty. However we want to continue
2690         // collecting remembered set entries for humongous regions that were not
2691         // reclaimed.
2692         r->rem_set()->set_state_complete();
2693       }
2694       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2695     }
2696     _total_humongous++;
2697 
2698     return false;
2699   }
2700 
2701   size_t total_humongous() const { return _total_humongous; }
2702   size_t candidate_humongous() const { return _candidate_humongous; }
2703 
2704   void flush_rem_set_entries() { _dcq.flush(); }
2705 };
2706 
2707 void G1CollectedHeap::register_humongous_regions_with_cset() {
2708   if (!G1EagerReclaimHumongousObjects) {
2709     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2710     return;
2711   }
2712   double time = os::elapsed_counter();
2713 
2714   // Collect reclaim candidate information and register candidates with cset.
2715   RegisterHumongousWithInCSetFastTestClosure cl;
2716   heap_region_iterate(&cl);
2717 
2718   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2719   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2720                                                                   cl.total_humongous(),
2721                                                                   cl.candidate_humongous());
2722   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2723 
2724   // Finally flush all remembered set entries to re-check into the global DCQS.
2725   cl.flush_rem_set_entries();
2726 }
2727 
2728 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2729   public:
2730     bool do_heap_region(HeapRegion* hr) {
2731       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2732         hr->verify_rem_set();
2733       }
2734       return false;
2735     }
2736 };
2737 
2738 uint G1CollectedHeap::num_task_queues() const {
2739   return _task_queues->size();
2740 }
2741 
2742 #if TASKQUEUE_STATS
2743 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2744   st->print_raw_cr("GC Task Stats");
2745   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2746   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2747 }
2748 
2749 void G1CollectedHeap::print_taskqueue_stats() const {
2750   if (!log_is_enabled(Trace, gc, task, stats)) {
2751     return;
2752   }
2753   Log(gc, task, stats) log;
2754   ResourceMark rm;
2755   LogStream ls(log.trace());
2756   outputStream* st = &ls;
2757 
2758   print_taskqueue_stats_hdr(st);
2759 
2760   TaskQueueStats totals;
2761   const uint n = num_task_queues();
2762   for (uint i = 0; i < n; ++i) {
2763     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2764     totals += task_queue(i)->stats;
2765   }
2766   st->print_raw("tot "); totals.print(st); st->cr();
2767 
2768   DEBUG_ONLY(totals.verify());
2769 }
2770 
2771 void G1CollectedHeap::reset_taskqueue_stats() {
2772   const uint n = num_task_queues();
2773   for (uint i = 0; i < n; ++i) {
2774     task_queue(i)->stats.reset();
2775   }
2776 }
2777 #endif // TASKQUEUE_STATS
2778 
2779 void G1CollectedHeap::wait_for_root_region_scanning() {
2780   double scan_wait_start = os::elapsedTime();
2781   // We have to wait until the CM threads finish scanning the
2782   // root regions as it's the only way to ensure that all the
2783   // objects on them have been correctly scanned before we start
2784   // moving them during the GC.
2785   bool waited = _cm->root_regions()->wait_until_scan_finished();
2786   double wait_time_ms = 0.0;
2787   if (waited) {
2788     double scan_wait_end = os::elapsedTime();
2789     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2790   }
2791   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2792 }
2793 
2794 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2795 private:
2796   G1HRPrinter* _hr_printer;
2797 public:
2798   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2799 
2800   virtual bool do_heap_region(HeapRegion* r) {
2801     _hr_printer->cset(r);
2802     return false;
2803   }
2804 };
2805 
2806 void G1CollectedHeap::start_new_collection_set() {
2807   collection_set()->start_incremental_building();
2808 
2809   clear_cset_fast_test();
2810 
2811   guarantee(_eden.length() == 0, "eden should have been cleared");
2812   g1_policy()->transfer_survivors_to_cset(survivor());
2813 }
2814 
2815 bool
2816 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2817   assert_at_safepoint_on_vm_thread();
2818   guarantee(!is_gc_active(), "collection is not reentrant");
2819 
2820   if (GCLocker::check_active_before_gc()) {
2821     return false;
2822   }
2823 
2824   _gc_timer_stw->register_gc_start();
2825 
2826   GCIdMark gc_id_mark;
2827   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2828 
2829   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2830   ResourceMark rm;
2831 
2832   g1_policy()->note_gc_start();
2833 
2834   wait_for_root_region_scanning();
2835 
2836   print_heap_before_gc();
2837   print_heap_regions();
2838   trace_heap_before_gc(_gc_tracer_stw);
2839 
2840   _verifier->verify_region_sets_optional();
2841   _verifier->verify_dirty_young_regions();
2842 
2843   // We should not be doing initial mark unless the conc mark thread is running
2844   if (!_cm_thread->should_terminate()) {
2845     // This call will decide whether this pause is an initial-mark
2846     // pause. If it is, in_initial_mark_gc() will return true
2847     // for the duration of this pause.
2848     g1_policy()->decide_on_conc_mark_initiation();
2849   }
2850 
2851   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2852   assert(!collector_state()->in_initial_mark_gc() ||
2853           collector_state()->in_young_only_phase(), "sanity");
2854 
2855   // We also do not allow mixed GCs during marking.
2856   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2857 
2858   // Record whether this pause is an initial mark. When the current
2859   // thread has completed its logging output and it's safe to signal
2860   // the CM thread, the flag's value in the policy has been reset.
2861   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2862 
2863   // Inner scope for scope based logging, timers, and stats collection
2864   {
2865     EvacuationInfo evacuation_info;
2866 
2867     if (collector_state()->in_initial_mark_gc()) {
2868       // We are about to start a marking cycle, so we increment the
2869       // full collection counter.
2870       increment_old_marking_cycles_started();
2871       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2872     }
2873 
2874     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2875 
2876     GCTraceCPUTime tcpu;
2877 
2878     G1HeapVerifier::G1VerifyType verify_type;
2879     FormatBuffer<> gc_string("Pause Young ");
2880     if (collector_state()->in_initial_mark_gc()) {
2881       gc_string.append("(Concurrent Start)");
2882       verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2883     } else if (collector_state()->in_young_only_phase()) {
2884       if (collector_state()->in_young_gc_before_mixed()) {
2885         gc_string.append("(Prepare Mixed)");
2886       } else {
2887         gc_string.append("(Normal)");
2888       }
2889       verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2890     } else {
2891       gc_string.append("(Mixed)");
2892       verify_type = G1HeapVerifier::G1VerifyMixed;
2893     }
2894     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2895 
2896     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2897                                                                   workers()->active_workers(),
2898                                                                   Threads::number_of_non_daemon_threads());
2899     active_workers = workers()->update_active_workers(active_workers);
2900     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2901 
2902     G1MonitoringScope ms(g1mm(),
2903                          false /* full_gc */,
2904                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2905 
2906     G1HeapTransition heap_transition(this);
2907     size_t heap_used_bytes_before_gc = used();
2908 
2909     // Don't dynamically change the number of GC threads this early.  A value of
2910     // 0 is used to indicate serial work.  When parallel work is done,
2911     // it will be set.
2912 
2913     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2914       IsGCActiveMark x;
2915 
2916       gc_prologue(false);
2917 
2918       if (VerifyRememberedSets) {
2919         log_info(gc, verify)("[Verifying RemSets before GC]");
2920         VerifyRegionRemSetClosure v_cl;
2921         heap_region_iterate(&v_cl);
2922       }
2923 
2924       _verifier->verify_before_gc(verify_type);
2925 
2926       _verifier->check_bitmaps("GC Start");
2927 
2928 #if COMPILER2_OR_JVMCI
2929       DerivedPointerTable::clear();
2930 #endif
2931 
2932       // Please see comment in g1CollectedHeap.hpp and
2933       // G1CollectedHeap::ref_processing_init() to see how
2934       // reference processing currently works in G1.
2935 
2936       // Enable discovery in the STW reference processor
2937       _ref_processor_stw->enable_discovery();
2938 
2939       {
2940         // We want to temporarily turn off discovery by the
2941         // CM ref processor, if necessary, and turn it back on
2942         // on again later if we do. Using a scoped
2943         // NoRefDiscovery object will do this.
2944         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2945 
2946         // Forget the current alloc region (we might even choose it to be part
2947         // of the collection set!).
2948         _allocator->release_mutator_alloc_region();
2949 
2950         // This timing is only used by the ergonomics to handle our pause target.
2951         // It is unclear why this should not include the full pause. We will
2952         // investigate this in CR 7178365.
2953         //
2954         // Preserving the old comment here if that helps the investigation:
2955         //
2956         // The elapsed time induced by the start time below deliberately elides
2957         // the possible verification above.
2958         double sample_start_time_sec = os::elapsedTime();
2959 
2960         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2961 
2962         if (collector_state()->in_initial_mark_gc()) {
2963           concurrent_mark()->pre_initial_mark();
2964         }
2965 
2966         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2967 
2968         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2969 
2970         // Make sure the remembered sets are up to date. This needs to be
2971         // done before register_humongous_regions_with_cset(), because the
2972         // remembered sets are used there to choose eager reclaim candidates.
2973         // If the remembered sets are not up to date we might miss some
2974         // entries that need to be handled.
2975         g1_rem_set()->cleanupHRRS();
2976 
2977         register_humongous_regions_with_cset();
2978 
2979         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2980 
2981         // We call this after finalize_cset() to
2982         // ensure that the CSet has been finalized.
2983         _cm->verify_no_cset_oops();
2984 
2985         if (_hr_printer.is_active()) {
2986           G1PrintCollectionSetClosure cl(&_hr_printer);
2987           _collection_set.iterate(&cl);
2988         }
2989 
2990         // Initialize the GC alloc regions.
2991         _allocator->init_gc_alloc_regions(evacuation_info);
2992 
2993         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length(
2994         pre_evacuate_collection_set();
2995 
2996         // Actually do the work...
2997         evacuate_collection_set(&per_thread_states);
2998 
2999         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3000 
3001         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3002         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3003 
3004         eagerly_reclaim_humongous_regions();
3005 
3006         record_obj_copy_mem_stats();
3007         _survivor_evac_stats.adjust_desired_plab_sz();
3008         _old_evac_stats.adjust_desired_plab_sz();
3009 
3010         double start = os::elapsedTime();
3011         start_new_collection_set();
3012         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3013 
3014         if (evacuation_failed()) {
3015           set_used(recalculate_used());
3016           if (_archive_allocator != NULL) {
3017             _archive_allocator->clear_used();
3018           }
3019           for (uint i = 0; i < ParallelGCThreads; i++) {
3020             if (_evacuation_failed_info_array[i].has_failed()) {
3021               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3022             }
3023           }
3024         } else {
3025           // The "used" of the the collection set have already been subtracted
3026           // when they were freed.  Add in the bytes evacuated.
3027           increase_used(g1_policy()->bytes_copied_during_gc());
3028         }
3029 
3030         if (collector_state()->in_initial_mark_gc()) {
3031           // We have to do this before we notify the CM threads that
3032           // they can start working to make sure that all the
3033           // appropriate initialization is done on the CM object.
3034           concurrent_mark()->post_initial_mark();
3035           // Note that we don't actually trigger the CM thread at
3036           // this point. We do that later when we're sure that
3037           // the current thread has completed its logging output.
3038         }
3039 
3040         allocate_dummy_regions();
3041 
3042         _allocator->init_mutator_alloc_region();
3043 
3044         {
3045           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3046           if (expand_bytes > 0) {
3047             size_t bytes_before = capacity();
3048             // No need for an ergo logging here,
3049             // expansion_amount() does this when it returns a value > 0.
3050             double expand_ms;
3051             if (!expand(expand_bytes, _workers, &expand_ms)) {
3052               // We failed to expand the heap. Cannot do anything about it.
3053             }
3054             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3055           }
3056         }
3057 
3058         // We redo the verification but now wrt to the new CSet which
3059         // has just got initialized after the previous CSet was freed.
3060         _cm->verify_no_cset_oops();
3061 
3062         // This timing is only used by the ergonomics to handle our pause target.
3063         // It is unclear why this should not include the full pause. We will
3064         // investigate this in CR 7178365.
3065         double sample_end_time_sec = os::elapsedTime();
3066         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3067         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTim
3068         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3069 
3070         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3071         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3072 
3073         if (VerifyRememberedSets) {
3074           log_info(gc, verify)("[Verifying RemSets after GC]");
3075           VerifyRegionRemSetClosure v_cl;
3076           heap_region_iterate(&v_cl);
3077         }
3078 
3079         _verifier->verify_after_gc(verify_type);
3080         _verifier->check_bitmaps("GC End");
3081 
3082         assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3083         _ref_processor_stw->verify_no_references_recorded();
3084 
3085         // CM reference discovery will be re-enabled if necessary.
3086       }
3087 
3088 #ifdef TRACESPINNING
3089       ParallelTaskTerminator::print_termination_counts();
3090 #endif
3091 
3092       gc_epilogue(false);
3093     }
3094 
3095     // Print the remainder of the GC log output.
3096     if (evacuation_failed()) {
3097       log_info(gc)("To-space exhausted");
3098     }
3099 
3100     g1_policy()->print_phases();
3101     heap_transition.print();
3102 
3103     // It is not yet to safe to tell the concurrent mark to
3104     // start as we have some optional output below. We don't want the
3105     // output from the concurrent mark thread interfering with this
3106     // logging output either.
3107 
3108     _hrm.verify_optional();
3109     _verifier->verify_region_sets_optional();
3110 
3111     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3112     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3113 
3114     print_heap_after_gc();
3115     print_heap_regions();
3116     trace_heap_after_gc(_gc_tracer_stw);
3117 
3118     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3119     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3120     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3121     // before any GC notifications are raised.
3122     g1mm()->update_sizes();
3123 
3124     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3125     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3126     _gc_timer_stw->register_gc_end();
3127     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3128   }
3129   // It should now be safe to tell the concurrent mark thread to start
3130   // without its logging output interfering with the logging output
3131   // that came from the pause.
3132 
3133   if (should_start_conc_mark) {
3134     // CAUTION: after the doConcurrentMark() call below,
3135     // the concurrent marking thread(s) could be running
3136     // concurrently with us. Make sure that anything after
3137     // this point does not assume that we are the only GC thread
3138     // running. Note: of course, the actual marking work will
3139     // not start until the safepoint itself is released in
3140     // SuspendibleThreadSet::desynchronize().
3141     do_concurrent_mark();
3142   }
3143 
3144   return true;
3145 }
3146 
3147 void G1CollectedHeap::remove_self_forwarding_pointers() {
3148   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3149   workers()->run_task(&rsfp_task);
3150 }
3151 
3152 void G1CollectedHeap::restore_after_evac_failure() {
3153   double remove_self_forwards_start = os::elapsedTime();
3154 
3155   remove_self_forwarding_pointers();
3156   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3157   _preserved_marks_set.restore(&task_executor);
3158 
3159   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000
3160 }
3161 
3162 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3163   if (!_evacuation_failed) {
3164     _evacuation_failed = true;
3165   }
3166 
3167   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3168   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3169 }
3170 
3171 bool G1ParEvacuateFollowersClosure::offer_termination() {
3172   EventGCPhaseParallel event;
3173   G1ParScanThreadState* const pss = par_scan_state();
3174   start_term_time();
3175   const bool res = terminator()->offer_termination();
3176   end_term_time();
3177   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3178   return res;
3179 }
3180 
3181 void G1ParEvacuateFollowersClosure::do_void() {
3182   EventGCPhaseParallel event;
3183   G1ParScanThreadState* const pss = par_scan_state();
3184   pss->trim_queue();
3185   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3186   do {
3187     EventGCPhaseParallel event;
3188     pss->steal_and_trim_queue(queues());
3189     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3190   } while (!offer_termination());
3191 }
3192 
3193 class G1ParTask : public AbstractGangTask {
3194 protected:
3195   G1CollectedHeap*         _g1h;
3196   G1ParScanThreadStateSet* _pss;
3197   RefToScanQueueSet*       _queues;
3198   G1RootProcessor*         _root_processor;
3199   ParallelTaskTerminator   _terminator;
3200   uint                     _n_workers;
3201 
3202 public:
3203   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcess
3204     : AbstractGangTask("G1 collection"),
3205       _g1h(g1h),
3206       _pss(per_thread_states),
3207       _queues(task_queues),
3208       _root_processor(root_processor),
3209       _terminator(n_workers, _queues),
3210       _n_workers(n_workers)
3211   {}
3212 
3213   void work(uint worker_id) {
3214     if (worker_id >= _n_workers) return;  // no work needed this round
3215 
3216     double start_sec = os::elapsedTime();
3217     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3218 
3219     {
3220       ResourceMark rm;
3221       HandleMark   hm;
3222 
3223       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3224 
3225       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3226       pss->set_ref_discoverer(rp);
3227 
3228       double start_strong_roots_sec = os::elapsedTime();
3229 
3230       _root_processor->evacuate_roots(pss, worker_id);
3231 
3232       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3233       // treating the nmethods visited to act as roots for concurrent marking.
3234       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3235       // objects copied by the current evacuation.
3236       _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3237 
3238       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3239 
3240       double term_sec = 0.0;
3241       size_t evac_term_attempts = 0;
3242       {
3243         double start = os::elapsedTime();
3244         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3245         evac.do_void();
3246 
3247         evac_term_attempts = evac.term_attempts();
3248         term_sec = evac.term_time();
3249         double elapsed_sec = os::elapsedTime() - start;
3250 
3251         G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3252         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3253         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3254         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3255       }
3256 
3257       assert(pss->queue_is_empty(), "should be empty");
3258 
3259       if (log_is_enabled(Debug, gc, task, stats)) {
3260         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3261         size_t lab_waste;
3262         size_t lab_undo_waste;
3263         pss->waste(lab_waste, lab_undo_waste);
3264         _g1h->print_termination_stats(worker_id,
3265                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3266                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3267                                       term_sec * 1000.0,                          /* evac term time */
3268                                       evac_term_attempts,                         /* evac term attempts */
3269                                       lab_waste,                                  /* alloc buffer waste */
3270                                       lab_undo_waste                              /* undo waste */
3271                                       );
3272       }
3273 
3274       // Close the inner scope so that the ResourceMark and HandleMark
3275       // destructors are executed here and are included as part of the
3276       // "GC Worker Time".
3277     }
3278     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3279   }
3280 };
3281 
3282 void G1CollectedHeap::print_termination_stats_hdr() {
3283   log_debug(gc, task, stats)("GC Termination Stats");
3284   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3285   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3286   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3287 }
3288 
3289 void G1CollectedHeap::print_termination_stats(uint worker_id,
3290                                               double elapsed_ms,
3291                                               double strong_roots_ms,
3292                                               double term_ms,
3293                                               size_t term_attempts,
3294                                               size_t alloc_buffer_waste,
3295                                               size_t undo_waste) const {
3296   log_debug(gc, task, stats)
3297               ("%3d %9.2f %9.2f %6.2f "
3298                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3299                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3300                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3301                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3302                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3303                alloc_buffer_waste * HeapWordSize / K,
3304                undo_waste * HeapWordSize / K);
3305 }
3306 
3307 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3308                                         bool class_unloading_occurred) {
3309   uint n_workers = workers()->active_workers();
3310 
3311   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3312   ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3313   workers()->run_task(&g1_unlink_task);
3314 }
3315 
3316 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3317                                        bool process_strings,
3318                                        bool process_string_dedup) {
3319   if (!process_strings && !process_string_dedup) {
3320     // Nothing to clean.
3321     return;
3322   }
3323 
3324   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3325   StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3326   workers()->run_task(&g1_unlink_task);
3327 }
3328 
3329 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3330  private:
3331   DirtyCardQueueSet* _queue;
3332   G1CollectedHeap* _g1h;
3333  public:
3334   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3335     _queue(queue), _g1h(g1h) { }
3336 
3337   virtual void work(uint worker_id) {
3338     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3339     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3340 
3341     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3342     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3343 
3344     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3345   }
3346 };
3347 
3348 void G1CollectedHeap::redirty_logged_cards() {
3349   double redirty_logged_cards_start = os::elapsedTime();
3350 
3351   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3352   dirty_card_queue_set().reset_for_par_iteration();
3353   workers()->run_task(&redirty_task);
3354 
3355   DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3356   dcq.merge_bufferlists(&dirty_card_queue_set());
3357   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3358 
3359   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0
3360 }
3361 
3362 // Weak Reference Processing support
3363 
3364 bool G1STWIsAliveClosure::do_object_b(oop p) {
3365   // An object is reachable if it is outside the collection set,
3366   // or is inside and copied.
3367   return !_g1h->is_in_cset(p) || p->is_forwarded();
3368 }
3369 
3370 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3371   assert(obj != NULL, "must not be NULL");
3372   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3373   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3374   // may falsely indicate that this is not the case here: however the collection set only
3375   // contains old regions when concurrent mark is not running.
3376   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3377 }
3378 
3379 // Non Copying Keep Alive closure
3380 class G1KeepAliveClosure: public OopClosure {
3381   G1CollectedHeap*_g1h;
3382 public:
3383   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3384   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3385   void do_oop(oop* p) {
3386     oop obj = *p;
3387     assert(obj != NULL, "the caller should have filtered out NULL values");
3388 
3389     const InCSetState cset_state =_g1h->in_cset_state(obj);
3390     if (!cset_state.is_in_cset_or_humongous()) {
3391       return;
3392     }
3393     if (cset_state.is_in_cset()) {
3394       assert( obj->is_forwarded(), "invariant" );
3395       *p = obj->forwardee();
3396     } else {
3397       assert(!obj->is_forwarded(), "invariant" );
3398       assert(cset_state.is_humongous(),
3399              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3400      _g1h->set_humongous_is_live(obj);
3401     }
3402   }
3403 };
3404 
3405 // Copying Keep Alive closure - can be called from both
3406 // serial and parallel code as long as different worker
3407 // threads utilize different G1ParScanThreadState instances
3408 // and different queues.
3409 
3410 class G1CopyingKeepAliveClosure: public OopClosure {
3411   G1CollectedHeap*         _g1h;
3412   G1ParScanThreadState*    _par_scan_state;
3413 
3414 public:
3415   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3416                             G1ParScanThreadState* pss):
3417     _g1h(g1h),
3418     _par_scan_state(pss)
3419   {}
3420 
3421   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3422   virtual void do_oop(      oop* p) { do_oop_work(p); }
3423 
3424   template <class T> void do_oop_work(T* p) {
3425     oop obj = RawAccess<>::oop_load(p);
3426 
3427     if (_g1h->is_in_cset_or_humongous(obj)) {
3428       // If the referent object has been forwarded (either copied
3429       // to a new location or to itself in the event of an
3430       // evacuation failure) then we need to update the reference
3431       // field and, if both reference and referent are in the G1
3432       // heap, update the RSet for the referent.
3433       //
3434       // If the referent has not been forwarded then we have to keep
3435       // it alive by policy. Therefore we have copy the referent.
3436       //
3437       // When the queue is drained (after each phase of reference processing)
3438       // the object and it's followers will be copied, the reference field set
3439       // to point to the new location, and the RSet updated.
3440       _par_scan_state->push_on_queue(p);
3441     }
3442   }
3443 };
3444 
3445 // Serial drain queue closure. Called as the 'complete_gc'
3446 // closure for each discovered list in some of the
3447 // reference processing phases.
3448 
3449 class G1STWDrainQueueClosure: public VoidClosure {
3450 protected:
3451   G1CollectedHeap* _g1h;
3452   G1ParScanThreadState* _par_scan_state;
3453 
3454   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3455 
3456 public:
3457   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3458     _g1h(g1h),
3459     _par_scan_state(pss)
3460   { }
3461 
3462   void do_void() {
3463     G1ParScanThreadState* const pss = par_scan_state();
3464     pss->trim_queue();
3465   }
3466 };
3467 
3468 // Parallel Reference Processing closures
3469 
3470 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3471 // processing during G1 evacuation pauses.
3472 
3473 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3474 private:
3475   G1CollectedHeap*          _g1h;
3476   G1ParScanThreadStateSet*  _pss;
3477   RefToScanQueueSet*        _queues;
3478   WorkGang*                 _workers;
3479 
3480 public:
3481   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3482                            G1ParScanThreadStateSet* per_thread_states,
3483                            WorkGang* workers,
3484                            RefToScanQueueSet *task_queues) :
3485     _g1h(g1h),
3486     _pss(per_thread_states),
3487     _queues(task_queues),
3488     _workers(workers)
3489   {
3490     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3491   }
3492 
3493   // Executes the given task using concurrent marking worker threads.
3494   virtual void execute(ProcessTask& task, uint ergo_workers);
3495 };
3496 
3497 // Gang task for possibly parallel reference processing
3498 
3499 class G1STWRefProcTaskProxy: public AbstractGangTask {
3500   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3501   ProcessTask&     _proc_task;
3502   G1CollectedHeap* _g1h;
3503   G1ParScanThreadStateSet* _pss;
3504   RefToScanQueueSet* _task_queues;
3505   ParallelTaskTerminator* _terminator;
3506 
3507 public:
3508   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3509                         G1CollectedHeap* g1h,
3510                         G1ParScanThreadStateSet* per_thread_states,
3511                         RefToScanQueueSet *task_queues,
3512                         ParallelTaskTerminator* terminator) :
3513     AbstractGangTask("Process reference objects in parallel"),
3514     _proc_task(proc_task),
3515     _g1h(g1h),
3516     _pss(per_thread_states),
3517     _task_queues(task_queues),
3518     _terminator(terminator)
3519   {}
3520 
3521   virtual void work(uint worker_id) {
3522     // The reference processing task executed by a single worker.
3523     ResourceMark rm;
3524     HandleMark   hm;
3525 
3526     G1STWIsAliveClosure is_alive(_g1h);
3527 
3528     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3529     pss->set_ref_discoverer(NULL);
3530 
3531     // Keep alive closure.
3532     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3533 
3534     // Complete GC closure
3535     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3536 
3537     // Call the reference processing task's work routine.
3538     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3539 
3540     // Note we cannot assert that the refs array is empty here as not all
3541     // of the processing tasks (specifically phase2 - pp2_work) execute
3542     // the complete_gc closure (which ordinarily would drain the queue) so
3543     // the queue may not be empty.
3544   }
3545 };
3546 
3547 // Driver routine for parallel reference processing.
3548 // Creates an instance of the ref processing gang
3549 // task and has the worker threads execute it.
3550 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3551   assert(_workers != NULL, "Need parallel worker threads.");
3552 
3553   assert(_workers->active_workers() >= ergo_workers,
3554          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3555          ergo_workers, _workers->active_workers());
3556   ParallelTaskTerminator terminator(ergo_workers, _queues);
3557   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3558 
3559   _workers->run_task(&proc_task_proxy, ergo_workers);
3560 }
3561 
3562 // End of weak reference support closures
3563 
3564 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3565   double ref_proc_start = os::elapsedTime();
3566 
3567   ReferenceProcessor* rp = _ref_processor_stw;
3568   assert(rp->discovery_enabled(), "should have been enabled");
3569 
3570   // Closure to test whether a referent is alive.
3571   G1STWIsAliveClosure is_alive(this);
3572 
3573   // Even when parallel reference processing is enabled, the processing
3574   // of JNI refs is serial and performed serially by the current thread
3575   // rather than by a worker. The following PSS will be used for processing
3576   // JNI refs.
3577 
3578   // Use only a single queue for this PSS.
3579   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3580   pss->set_ref_discoverer(NULL);
3581   assert(pss->queue_is_empty(), "pre-condition");
3582 
3583   // Keep alive closure.
3584   G1CopyingKeepAliveClosure keep_alive(this, pss);
3585 
3586   // Serial Complete GC closure
3587   G1STWDrainQueueClosure drain_queue(this, pss);
3588 
3589   // Setup the soft refs policy...
3590   rp->setup_policy(false);
3591 
3592   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3593 
3594   ReferenceProcessorStats stats;
3595   if (!rp->processing_is_mt()) {
3596     // Serial reference processing...
3597     stats = rp->process_discovered_references(&is_alive,
3598                                               &keep_alive,
3599                                               &drain_queue,
3600                                               NULL,
3601                                               pt);
3602   } else {
3603     uint no_of_gc_workers = workers()->active_workers();
3604 
3605     // Parallel reference processing
3606     assert(no_of_gc_workers <= rp->max_num_queues(),
3607            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3608            no_of_gc_workers,  rp->max_num_queues());
3609 
3610     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3611     stats = rp->process_discovered_references(&is_alive,
3612                                               &keep_alive,
3613                                               &drain_queue,
3614                                               &par_task_executor,
3615                                               pt);
3616   }
3617 
3618   _gc_tracer_stw->report_gc_reference_stats(stats);
3619 
3620   // We have completed copying any necessary live referent objects.
3621   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3622 
3623   make_pending_list_reachable();
3624 
3625   rp->verify_no_references_recorded();
3626 
3627   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3628   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3629 }
3630 
3631 void G1CollectedHeap::make_pending_list_reachable() {
3632   if (collector_state()->in_initial_mark_gc()) {
3633     oop pll_head = Universe::reference_pending_list();
3634     if (pll_head != NULL) {
3635       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3636       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3637     }
3638   }
3639 }
3640 
3641 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3642   double merge_pss_time_start = os::elapsedTime();
3643   per_thread_states->flush();
3644   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3645 }
3646 
3647 void G1CollectedHeap::pre_evacuate_collection_set() {
3648   _expand_heap_after_alloc_failure = true;
3649   _evacuation_failed = false;
3650 
3651   // Disable the hot card cache.
3652   _hot_card_cache->reset_hot_cache_claimed_index();
3653   _hot_card_cache->set_use_cache(false);
3654 
3655   g1_rem_set()->prepare_for_oops_into_collection_set_do();
3656   _preserved_marks_set.assert_empty();
3657 
3658   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3659 
3660   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3661   if (collector_state()->in_initial_mark_gc()) {
3662     double start_clear_claimed_marks = os::elapsedTime();
3663 
3664     ClassLoaderDataGraph::clear_claimed_marks();
3665 
3666     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3667     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3668   }
3669 }
3670 
3671 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3672   // Should G1EvacuationFailureALot be in effect for this GC?
3673   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3674 
3675   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3676 
3677   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3678 
3679   double start_par_time_sec = os::elapsedTime();
3680   double end_par_time_sec;
3681 
3682   {
3683     const uint n_workers = workers()->active_workers();
3684     G1RootProcessor root_processor(this, n_workers);
3685     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3686 
3687     print_termination_stats_hdr();
3688 
3689     workers()->run_task(&g1_par_task);
3690     end_par_time_sec = os::elapsedTime();
3691 
3692     // Closing the inner scope will execute the destructor
3693     // for the G1RootProcessor object. We record the current
3694     // elapsed time before closing the scope so that time
3695     // taken for the destructor is NOT included in the
3696     // reported parallel time.
3697   }
3698 
3699   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3700   phase_times->record_par_time(par_time_ms);
3701 
3702   double code_root_fixup_time_ms =
3703         (os::elapsedTime() - end_par_time_sec) * 1000.0;
3704   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3705 }
3706 
3707 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_sta
3708   // Also cleans the card table from temporary duplicate detection information used
3709   // during UpdateRS/ScanRS.
3710   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3711 
3712   // Process any discovered reference objects - we have
3713   // to do this _before_ we retire the GC alloc regions
3714   // as we may have to copy some 'reachable' referent
3715   // objects (and their reachable sub-graphs) that were
3716   // not copied during the pause.
3717   process_discovered_references(per_thread_states);
3718 
3719   // FIXME
3720   // CM's reference processing also cleans up the string table.
3721   // Should we do that here also? We could, but it is a serial operation
3722   // and could significantly increase the pause time.
3723 
3724   G1STWIsAliveClosure is_alive(this);
3725   G1KeepAliveClosure keep_alive(this);
3726 
3727   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3728                               g1_policy()->phase_times()->weak_phase_times());
3729 
3730   if (G1StringDedup::is_enabled()) {
3731     double fixup_start = os::elapsedTime();
3732 
3733     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3734 
3735     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3736     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3737   }
3738 
3739   if (evacuation_failed()) {
3740     restore_after_evac_failure();
3741 
3742     // Reset the G1EvacuationFailureALot counters and flags
3743     // Note: the values are reset only when an actual
3744     // evacuation failure occurs.
3745     NOT_PRODUCT(reset_evacuation_should_fail();)
3746   }
3747 
3748   _preserved_marks_set.assert_empty();
3749 
3750   _allocator->release_gc_alloc_regions(evacuation_info);
3751 
3752   merge_per_thread_state_info(per_thread_states);
3753 
3754   // Reset and re-enable the hot card cache.
3755   // Note the counts for the cards in the regions in the
3756   // collection set are reset when the collection set is freed.
3757   _hot_card_cache->reset_hot_cache();
3758   _hot_card_cache->set_use_cache(true);
3759 
3760   purge_code_root_memory();
3761 
3762   redirty_logged_cards();
3763 #if COMPILER2_OR_JVMCI
3764   double start = os::elapsedTime();
3765   DerivedPointerTable::update_pointers();
3766   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3767 #endif
3768   g1_policy()->print_age_table();
3769 }
3770 
3771 void G1CollectedHeap::record_obj_copy_mem_stats() {
3772   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3773 
3774   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3775                                                create_g1_evac_summary(&_old_evac_stats));
3776 }
3777 
3778 void G1CollectedHeap::free_region(HeapRegion* hr,
3779                                   FreeRegionList* free_list,
3780                                   bool skip_remset,
3781                                   bool skip_hot_card_cache,
3782                                   bool locked) {
3783   assert(!hr->is_free(), "the region should not be free");
3784   assert(!hr->is_empty(), "the region should not be empty");
3785   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3786   assert(free_list != NULL, "pre-condition");
3787 
3788   if (G1VerifyBitmaps) {
3789     MemRegion mr(hr->bottom(), hr->end());
3790     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3791   }
3792 
3793   // Clear the card counts for this region.
3794   // Note: we only need to do this if the region is not young
3795   // (since we don't refine cards in young regions).
3796   if (!skip_hot_card_cache && !hr->is_young()) {
3797     _hot_card_cache->reset_card_counts(hr);
3798   }
3799   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3800   _g1_policy->remset_tracker()->update_at_free(hr);
3801   free_list->add_ordered(hr);
3802 }
3803 
3804 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3805                                             FreeRegionList* free_list) {
3806   assert(hr->is_humongous(), "this is only for humongous regions");
3807   assert(free_list != NULL, "pre-condition");
3808   hr->clear_humongous();
3809   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3810 }
3811 
3812 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3813                                            const uint humongous_regions_removed) {
3814   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3815     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3816     _old_set.bulk_remove(old_regions_removed);
3817     _humongous_set.bulk_remove(humongous_regions_removed);
3818   }
3819 
3820 }
3821 
3822 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3823   assert(list != NULL, "list can't be null");
3824   if (!list->is_empty()) {
3825     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3826     _hrm.insert_list_into_free_list(list);
3827   }
3828 }
3829 
3830 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3831   decrease_used(bytes);
3832 }
3833 
3834 class G1FreeCollectionSetTask : public AbstractGangTask {
3835 private:
3836 
3837   // Closure applied to all regions in the collection set to do work that needs to
3838   // be done serially in a single thread.
3839   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3840   private:
3841     EvacuationInfo* _evacuation_info;
3842     const size_t* _surviving_young_words;
3843 
3844     // Bytes used in successfully evacuated regions before the evacuation.
3845     size_t _before_used_bytes;
3846     // Bytes used in unsucessfully evacuated regions before the evacuation
3847     size_t _after_used_bytes;
3848 
3849     size_t _bytes_allocated_in_old_since_last_gc;
3850 
3851     size_t _failure_used_words;
3852     size_t _failure_waste_words;
3853 
3854     FreeRegionList _local_free_list;
3855   public:
3856     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3857       HeapRegionClosure(),
3858       _evacuation_info(evacuation_info),
3859       _surviving_young_words(surviving_young_words),
3860       _before_used_bytes(0),
3861       _after_used_bytes(0),
3862       _bytes_allocated_in_old_since_last_gc(0),
3863       _failure_used_words(0),
3864       _failure_waste_words(0),
3865       _local_free_list("Local Region List for CSet Freeing") {
3866     }
3867 
3868     virtual bool do_heap_region(HeapRegion* r) {
3869       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3870 
3871       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3872       g1h->clear_in_cset(r);
3873 
3874       if (r->is_young()) {
3875         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_lengt
3876                "Young index %d is wrong for region %u of type %s with %u young regions",
3877                r->young_index_in_cset(),
3878                r->hrm_index(),
3879                r->get_type_str(),
3880                g1h->collection_set()->young_region_length());
3881         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3882         r->record_surv_words_in_group(words_survived);
3883       }
3884 
3885       if (!r->evacuation_failed()) {
3886         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3887         _before_used_bytes += r->used();
3888         g1h->free_region(r,
3889                          &_local_free_list,
3890                          true, /* skip_remset */
3891                          true, /* skip_hot_card_cache */
3892                          true  /* locked */);
3893       } else {
3894         r->uninstall_surv_rate_group();
3895         r->set_young_index_in_cset(-1);
3896         r->set_evacuation_failed(false);
3897         // When moving a young gen region to old gen, we "allocate" that whole region
3898         // there. This is in addition to any already evacuated objects. Notify the
3899         // policy about that.
3900         // Old gen regions do not cause an additional allocation: both the objects
3901         // still in the region and the ones already moved are accounted for elsewhere.
3902         if (r->is_young()) {
3903           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3904         }
3905         // The region is now considered to be old.
3906         r->set_old();
3907         // Do some allocation statistics accounting. Regions that failed evacuation
3908         // are always made old, so there is no need to update anything in the young
3909         // gen statistics, but we need to update old gen statistics.
3910         size_t used_words = r->marked_bytes() / HeapWordSize;
3911 
3912         _failure_used_words += used_words;
3913         _failure_waste_words += HeapRegion::GrainWords - used_words;
3914 
3915         g1h->old_set_add(r);
3916         _after_used_bytes += r->used();
3917       }
3918       return false;
3919     }
3920 
3921     void complete_work() {
3922       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3923 
3924       _evacuation_info->set_regions_freed(_local_free_list.length());
3925       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3926 
3927       g1h->prepend_to_freelist(&_local_free_list);
3928       g1h->decrement_summary_bytes(_before_used_bytes);
3929 
3930       G1Policy* policy = g1h->g1_policy();
3931       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3932 
3933       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3934     }
3935   };
3936 
3937   G1CollectionSet* _collection_set;
3938   G1SerialFreeCollectionSetClosure _cl;
3939   const size_t* _surviving_young_words;
3940 
3941   size_t _rs_lengths;
3942 
3943   volatile jint _serial_work_claim;
3944 
3945   struct WorkItem {
3946     uint region_idx;
3947     bool is_young;
3948     bool evacuation_failed;
3949 
3950     WorkItem(HeapRegion* r) {
3951       region_idx = r->hrm_index();
3952       is_young = r->is_young();
3953       evacuation_failed = r->evacuation_failed();
3954     }
3955   };
3956 
3957   volatile size_t _parallel_work_claim;
3958   size_t _num_work_items;
3959   WorkItem* _work_items;
3960 
3961   void do_serial_work() {
3962     // Need to grab the lock to be allowed to modify the old region list.
3963     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3964     _collection_set->iterate(&_cl);
3965   }
3966 
3967   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3968     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3969 
3970     HeapRegion* r = g1h->region_at(region_idx);
3971     assert(!g1h->is_on_master_free_list(r), "sanity");
3972 
3973     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3974 
3975     if (!is_young) {
3976       g1h->_hot_card_cache->reset_card_counts(r);
3977     }
3978 
3979     if (!evacuation_failed) {
3980       r->rem_set()->clear_locked();
3981     }
3982   }
3983 
3984   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3985   private:
3986     size_t _cur_idx;
3987     WorkItem* _work_items;
3988   public:
3989     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3990 
3991     virtual bool do_heap_region(HeapRegion* r) {
3992       _work_items[_cur_idx++] = WorkItem(r);
3993       return false;
3994     }
3995   };
3996 
3997   void prepare_work() {
3998     G1PrepareFreeCollectionSetClosure cl(_work_items);
3999     _collection_set->iterate(&cl);
4000   }
4001 
4002   void complete_work() {
4003     _cl.complete_work();
4004 
4005     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4006     policy->record_max_rs_lengths(_rs_lengths);
4007     policy->cset_regions_freed();
4008   }
4009 public:
4010   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_w
4011     AbstractGangTask("G1 Free Collection Set"),
4012     _collection_set(collection_set),
4013     _cl(evacuation_info, surviving_young_words),
4014     _surviving_young_words(surviving_young_words),
4015     _rs_lengths(0),
4016     _serial_work_claim(0),
4017     _parallel_work_claim(0),
4018     _num_work_items(collection_set->region_length()),
4019     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4020     prepare_work();
4021   }
4022 
4023   ~G1FreeCollectionSetTask() {
4024     complete_work();
4025     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4026   }
4027 
4028   // Chunk size for work distribution. The chosen value has been determined experimentally
4029   // to be a good tradeoff between overhead and achievable parallelism.
4030   static uint chunk_size() { return 32; }
4031 
4032   virtual void work(uint worker_id) {
4033     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4034 
4035     // Claim serial work.
4036     if (_serial_work_claim == 0) {
4037       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4038       if (value == 0) {
4039         double serial_time = os::elapsedTime();
4040         do_serial_work();
4041         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4042       }
4043     }
4044 
4045     // Start parallel work.
4046     double young_time = 0.0;
4047     bool has_young_time = false;
4048     double non_young_time = 0.0;
4049     bool has_non_young_time = false;
4050 
4051     while (true) {
4052       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4053       size_t cur = end - chunk_size();
4054 
4055       if (cur >= _num_work_items) {
4056         break;
4057       }
4058 
4059       EventGCPhaseParallel event;
4060       double start_time = os::elapsedTime();
4061 
4062       end = MIN2(end, _num_work_items);
4063 
4064       for (; cur < end; cur++) {
4065         bool is_young = _work_items[cur].is_young;
4066 
4067         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4068 
4069         double end_time = os::elapsedTime();
4070         double time_taken = end_time - start_time;
4071         if (is_young) {
4072           young_time += time_taken;
4073           has_young_time = true;
4074           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4075         } else {
4076           non_young_time += time_taken;
4077           has_non_young_time = true;
4078           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4079         }
4080         start_time = end_time;
4081       }
4082     }
4083 
4084     if (has_young_time) {
4085       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4086     }
4087     if (has_non_young_time) {
4088       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4089     }
4090   }
4091 };
4092 
4093 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* s
4094   _eden.clear();
4095 
4096   double free_cset_start_time = os::elapsedTime();
4097 
4098   {
4099     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4100     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4101 
4102     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4103 
4104     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4105                         cl.name(),
4106                         num_workers,
4107                         _collection_set.region_length());
4108     workers()->run_task(&cl, num_workers);
4109   }
4110   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4111 
4112   collection_set->clear();
4113 }
4114 
4115 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4116  private:
4117   FreeRegionList* _free_region_list;
4118   HeapRegionSet* _proxy_set;
4119   uint _humongous_objects_reclaimed;
4120   uint _humongous_regions_reclaimed;
4121   size_t _freed_bytes;
4122  public:
4123 
4124   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4125     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) 
4126   }
4127 
4128   virtual bool do_heap_region(HeapRegion* r) {
4129     if (!r->is_starts_humongous()) {
4130       return false;
4131     }
4132 
4133     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4134 
4135     oop obj = (oop)r->bottom();
4136     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4137 
4138     // The following checks whether the humongous object is live are sufficient.
4139     // The main additional check (in addition to having a reference from the roots
4140     // or the young gen) is whether the humongous object has a remembered set entry.
4141     //
4142     // A humongous object cannot be live if there is no remembered set for it
4143     // because:
4144     // - there can be no references from within humongous starts regions referencing
4145     // the object because we never allocate other objects into them.
4146     // (I.e. there are no intra-region references that may be missed by the
4147     // remembered set)
4148     // - as soon there is a remembered set entry to the humongous starts region
4149     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4150     // until the end of a concurrent mark.
4151     //
4152     // It is not required to check whether the object has been found dead by marking
4153     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4154     // all objects allocated during that time are considered live.
4155     // SATB marking is even more conservative than the remembered set.
4156     // So if at this point in the collection there is no remembered set entry,
4157     // nobody has a reference to it.
4158     // At the start of collection we flush all refinement logs, and remembered sets
4159     // are completely up-to-date wrt to references to the humongous object.
4160     //
4161     // Other implementation considerations:
4162     // - never consider object arrays at this time because they would pose
4163     // considerable effort for cleaning up the the remembered sets. This is
4164     // required because stale remembered sets might reference locations that
4165     // are currently allocated into.
4166     uint region_idx = r->hrm_index();
4167     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4168         !r->rem_set()->is_empty()) {
4169       log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT "  with remset " SI
4170                                region_idx,
4171                                (size_t)obj->size() * HeapWordSize,
4172                                p2i(r->bottom()),
4173                                r->rem_set()->occupied(),
4174                                r->rem_set()->strong_code_roots_list_length(),
4175                                next_bitmap->is_marked(r->bottom()),
4176                                g1h->is_humongous_reclaim_candidate(region_idx),
4177                                obj->is_typeArray()
4178                               );
4179       return false;
4180     }
4181 
4182     guarantee(obj->is_typeArray(),
4183               "Only eagerly reclaiming type arrays is supported, but the object "
4184               PTR_FORMAT " is not.", p2i(r->bottom()));
4185 
4186     log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_
4187                              region_idx,
4188                              (size_t)obj->size() * HeapWordSize,
4189                              p2i(r->bottom()),
4190                              r->rem_set()->occupied(),
4191                              r->rem_set()->strong_code_roots_list_length(),
4192                              next_bitmap->is_marked(r->bottom()),
4193                              g1h->is_humongous_reclaim_candidate(region_idx),
4194                              obj->is_typeArray()
4195                             );
4196 
4197     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4198     cm->humongous_object_eagerly_reclaimed(r);
4199     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4200            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4201            region_idx,
4202            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4203            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4204     _humongous_objects_reclaimed++;
4205     do {
4206       HeapRegion* next = g1h->next_region_in_humongous(r);
4207       _freed_bytes += r->used();
4208       r->set_containing_set(NULL);
4209       _humongous_regions_reclaimed++;
4210       g1h->free_humongous_region(r, _free_region_list);
4211       r = next;
4212     } while (r != NULL);
4213 
4214     return false;
4215   }
4216 
4217   uint humongous_objects_reclaimed() {
4218     return _humongous_objects_reclaimed;
4219   }
4220 
4221   uint humongous_regions_reclaimed() {
4222     return _humongous_regions_reclaimed;
4223   }
4224 
4225   size_t bytes_freed() const {
4226     return _freed_bytes;
4227   }
4228 };
4229 
4230 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4231   assert_at_safepoint_on_vm_thread();
4232 
4233   if (!G1EagerReclaimHumongousObjects ||
4234       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4235     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4236     return;
4237   }
4238 
4239   double start_time = os::elapsedTime();
4240 
4241   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4242 
4243   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4244   heap_region_iterate(&cl);
4245 
4246   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4247 
4248   G1HRPrinter* hrp = hr_printer();
4249   if (hrp->is_active()) {
4250     FreeRegionListIterator iter(&local_cleanup_list);
4251     while (iter.more_available()) {
4252       HeapRegion* hr = iter.get_next();
4253       hrp->cleanup(hr);
4254     }
4255   }
4256 
4257   prepend_to_freelist(&local_cleanup_list);
4258   decrement_summary_bytes(cl.bytes_freed());
4259 
4260   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4261                                                                     cl.humongous_objects_reclaimed());
4262 }
4263 
4264 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4265 public:
4266   virtual bool do_heap_region(HeapRegion* r) {
4267     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4268     G1CollectedHeap::heap()->clear_in_cset(r);
4269     r->set_young_index_in_cset(-1);
4270     return false;
4271   }
4272 };
4273 
4274 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4275   G1AbandonCollectionSetClosure cl;
4276   collection_set->iterate(&cl);
4277 
4278   collection_set->clear();
4279   collection_set->stop_incremental_building();
4280 }
4281 
4282 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4283   return _allocator->is_retained_old_region(hr);
4284 }
4285 
4286 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4287   _eden.add(hr);
4288   _g1_policy->set_region_eden(hr);
4289 }
4290 
4291 #ifdef ASSERT
4292 
4293 class NoYoungRegionsClosure: public HeapRegionClosure {
4294 private:
4295   bool _success;
4296 public:
4297   NoYoungRegionsClosure() : _success(true) { }
4298   bool do_heap_region(HeapRegion* r) {
4299     if (r->is_young()) {
4300       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4301                             p2i(r->bottom()), p2i(r->end()));
4302       _success = false;
4303     }
4304     return false;
4305   }
4306   bool success() { return _success; }
4307 };
4308 
4309 bool G1CollectedHeap::check_young_list_empty() {
4310   bool ret = (young_regions_count() == 0);
4311 
4312   NoYoungRegionsClosure closure;
4313   heap_region_iterate(&closure);
4314   ret = ret && closure.success();
4315 
4316   return ret;
4317 }
4318 
4319 #endif // ASSERT
4320 
4321 class TearDownRegionSetsClosure : public HeapRegionClosure {
4322   HeapRegionSet *_old_set;
4323 
4324 public:
4325   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4326 
4327   bool do_heap_region(HeapRegion* r) {
4328     if (r->is_old()) {
4329       _old_set->remove(r);
4330     } else if(r->is_young()) {
4331       r->uninstall_surv_rate_group();
4332     } else {
4333       // We ignore free regions, we'll empty the free list afterwards.
4334       // We ignore humongous and archive regions, we're not tearing down these
4335       // sets.
4336       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4337              "it cannot be another type");
4338     }
4339     return false;
4340   }
4341 
4342   ~TearDownRegionSetsClosure() {
4343     assert(_old_set->is_empty(), "post-condition");
4344   }
4345 };
4346 
4347 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4348   assert_at_safepoint_on_vm_thread();
4349 
4350   if (!free_list_only) {
4351     TearDownRegionSetsClosure cl(&_old_set);
4352     heap_region_iterate(&cl);
4353 
4354     // Note that emptying the _young_list is postponed and instead done as
4355     // the first step when rebuilding the regions sets again. The reason for
4356     // this is that during a full GC string deduplication needs to know if
4357     // a collected region was young or old when the full GC was initiated.
4358   }
4359   _hrm.remove_all_free_regions();
4360 }
4361 
4362 void G1CollectedHeap::increase_used(size_t bytes) {
4363   _summary_bytes_used += bytes;
4364 }
4365 
4366 void G1CollectedHeap::decrease_used(size_t bytes) {
4367   assert(_summary_bytes_used >= bytes,
4368          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4369          _summary_bytes_used, bytes);
4370   _summary_bytes_used -= bytes;
4371 }
4372 
4373 void G1CollectedHeap::set_used(size_t bytes) {
4374   _summary_bytes_used = bytes;
4375 }
4376 
4377 class RebuildRegionSetsClosure : public HeapRegionClosure {
4378 private:
4379   bool _free_list_only;
4380 
4381   HeapRegionSet* _old_set;
4382   HeapRegionManager* _hrm;
4383 
4384   size_t _total_used;
4385 
4386 public:
4387   RebuildRegionSetsClosure(bool free_list_only,
4388                            HeapRegionSet* old_set,
4389                            HeapRegionManager* hrm) :
4390     _free_list_only(free_list_only),
4391     _old_set(old_set), _hrm(hrm), _total_used(0) {
4392     assert(_hrm->num_free_regions() == 0, "pre-condition");
4393     if (!free_list_only) {
4394       assert(_old_set->is_empty(), "pre-condition");
4395     }
4396   }
4397 
4398   bool do_heap_region(HeapRegion* r) {
4399     // After full GC, no region should have a remembered set.
4400     r->rem_set()->clear(true);
4401     if (r->is_empty()) {
4402       // Add free regions to the free list
4403       r->set_free();
4404       _hrm->insert_into_free_list(r);
4405     } else if (!_free_list_only) {
4406 
4407       if (r->is_archive() || r->is_humongous()) {
4408         // We ignore archive and humongous regions. We left these sets unchanged.
4409       } else {
4410         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4411         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4412         r->move_to_old();
4413         _old_set->add(r);
4414       }
4415       _total_used += r->used();
4416     }
4417 
4418     return false;
4419   }
4420 
4421   size_t total_used() {
4422     return _total_used;
4423   }
4424 };
4425 
4426 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4427   assert_at_safepoint_on_vm_thread();
4428 
4429   if (!free_list_only) {
4430     _eden.clear();
4431     _survivor.clear();
4432   }
4433 
4434   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4435   heap_region_iterate(&cl);
4436 
4437   if (!free_list_only) {
4438     set_used(cl.total_used());
4439     if (_archive_allocator != NULL) {
4440       _archive_allocator->clear_used();
4441     }
4442   }
4443   assert(used_unlocked() == recalculate_used(),
4444          "inconsistent used_unlocked(), "
4445          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4446          used_unlocked(), recalculate_used());
4447 }
4448 
4449 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4450   HeapRegion* hr = heap_region_containing(p);
4451   return hr->is_in(p);
4452 }
4453 
4454 // Methods for the mutator alloc region
4455 
4456 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4457                                                       bool force) {
4458   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4459   bool should_allocate = g1_policy()->should_allocate_mutator_region();
4460   if (force || should_allocate) {
4461     HeapRegion* new_alloc_region = new_region(word_size,
4462                                               false /* is_old */,
4463                                               false /* do_expand */);
4464     if (new_alloc_region != NULL) {
4465       set_region_short_lived_locked(new_alloc_region);
4466       _hr_printer.alloc(new_alloc_region, !should_allocate);
4467       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4468       _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4469       return new_alloc_region;
4470     }
4471   }
4472   return NULL;
4473 }
4474 
4475 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4476                                                   size_t allocated_bytes) {
4477   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4478   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4479 
4480   collection_set()->add_eden_region(alloc_region);
4481   increase_used(allocated_bytes);
4482   _hr_printer.retire(alloc_region);
4483   // We update the eden sizes here, when the region is retired,
4484   // instead of when it's allocated, since this is the point that its
4485   // used space has been recorded in _summary_bytes_used.
4486   g1mm()->update_eden_size();
4487 }
4488 
4489 // Methods for the GC alloc regions
4490 
4491 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4492   if (dest.is_old()) {
4493     return true;
4494   } else {
4495     return survivor_regions_count() < g1_policy()->max_survivor_regions();
4496   }
4497 }
4498 
4499 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4500   assert(FreeList_lock->owned_by_self(), "pre-condition");
4501 
4502   if (!has_more_regions(dest)) {
4503     return NULL;
4504   }
4505 
4506   const bool is_survivor = dest.is_young();
4507 
4508   HeapRegion* new_alloc_region = new_region(word_size,
4509                                             !is_survivor,
4510                                             true /* do_expand */);
4511   if (new_alloc_region != NULL) {
4512     if (is_survivor) {
4513       new_alloc_region->set_survivor();
4514       _survivor.add(new_alloc_region);
4515       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4516     } else {
4517       new_alloc_region->set_old();
4518       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4519     }
4520     _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4521     _hr_printer.alloc(new_alloc_region);
4522     bool during_im = collector_state()->in_initial_mark_gc();
4523     new_alloc_region->note_start_of_copying(during_im);
4524     return new_alloc_region;
4525   }
4526   return NULL;
4527 }
4528 
4529 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4530                                              size_t allocated_bytes,
4531                                              InCSetState dest) {
4532   bool during_im = collector_state()->in_initial_mark_gc();
4533   alloc_region->note_end_of_copying(during_im);
4534   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4535   if (dest.is_old()) {
4536     old_set_add(alloc_region);
4537   }
4538   _hr_printer.retire(alloc_region);
4539 }
4540 
4541 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4542   bool expanded = false;
4543   uint index = _hrm.find_highest_free(&expanded);
4544 
4545   if (index != G1_NO_HRM_INDEX) {
4546     if (expanded) {
4547       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_
4548                                 HeapRegion::GrainWords * HeapWordSize);
4549     }
4550     _hrm.allocate_free_regions_starting_at(index, 1);
4551     return region_at(index);
4552   }
4553   return NULL;
4554 }
4555 
4556 // Optimized nmethod scanning
4557 
4558 class RegisterNMethodOopClosure: public OopClosure {
4559   G1CollectedHeap* _g1h;
4560   nmethod* _nm;
4561 
4562   template <class T> void do_oop_work(T* p) {
4563     T heap_oop = RawAccess<>::oop_load(p);
4564     if (!CompressedOops::is_null(heap_oop)) {
4565       oop obj = CompressedOops::decode_not_null(heap_oop);
4566       HeapRegion* hr = _g1h->heap_region_containing(obj);
4567       assert(!hr->is_continues_humongous(),
4568              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4569              " starting at " HR_FORMAT,
4570              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4571 
4572       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4573       hr->add_strong_code_root_locked(_nm);
4574     }
4575   }
4576 
4577 public:
4578   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4579     _g1h(g1h), _nm(nm) {}
4580 
4581   void do_oop(oop* p)       { do_oop_work(p); }
4582   void do_oop(narrowOop* p) { do_oop_work(p); }
4583 };
4584 
4585 class UnregisterNMethodOopClosure: public OopClosure {
4586   G1CollectedHeap* _g1h;
4587   nmethod* _nm;
4588 
4589   template <class T> void do_oop_work(T* p) {
4590     T heap_oop = RawAccess<>::oop_load(p);
4591     if (!CompressedOops::is_null(heap_oop)) {
4592       oop obj = CompressedOops::decode_not_null(heap_oop);
4593       HeapRegion* hr = _g1h->heap_region_containing(obj);
4594       assert(!hr->is_continues_humongous(),
4595              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4596              " starting at " HR_FORMAT,
4597              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4598 
4599       hr->remove_strong_code_root(_nm);
4600     }
4601   }
4602 
4603 public:
4604   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4605     _g1h(g1h), _nm(nm) {}
4606 
4607   void do_oop(oop* p)       { do_oop_work(p); }
4608   void do_oop(narrowOop* p) { do_oop_work(p); }
4609 };
4610 
4611 // Returns true if the reference points to an object that
4612 // can move in an incremental collection.
4613 bool G1CollectedHeap::is_scavengable(oop obj) {
4614   HeapRegion* hr = heap_region_containing(obj);
4615   return !hr->is_pinned();
4616 }
4617 
4618 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4619   guarantee(nm != NULL, "sanity");
4620   RegisterNMethodOopClosure reg_cl(this, nm);
4621   nm->oops_do(&reg_cl);
4622 }
4623 
4624 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4625   guarantee(nm != NULL, "sanity");
4626   UnregisterNMethodOopClosure reg_cl(this, nm);
4627   nm->oops_do(&reg_cl, true);
4628 }
4629 
4630 void G1CollectedHeap::purge_code_root_memory() {
4631   double purge_start = os::elapsedTime();
4632   G1CodeRootSet::purge();
4633   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4634   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4635 }
4636 
4637 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4638   G1CollectedHeap* _g1h;
4639 
4640 public:
4641   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4642     _g1h(g1h) {}
4643 
4644   void do_code_blob(CodeBlob* cb) {
4645     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4646     if (nm == NULL) {
4647       return;
4648     }
4649 
4650     if (ScavengeRootsInCode) {
4651       _g1h->register_nmethod(nm);
4652     }
4653   }
4654 };
4655 
4656 void G1CollectedHeap::rebuild_strong_code_roots() {
4657   RebuildStrongCodeRootClosure blob_cl(this);
4658   CodeCache::blobs_do(&blob_cl);
4659 }
4660 
4661 void G1CollectedHeap::initialize_serviceability() {
4662   _g1mm->initialize_serviceability();
4663 }
4664 
4665 MemoryUsage G1CollectedHeap::memory_usage() {
4666   return _g1mm->memory_usage();
4667 }
4668 
4669 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4670   return _g1mm->memory_managers();
4671 }
4672 
4673 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4674   return _g1mm->memory_pools();
4675 }
--- EOF ---