1/*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25#include "precompiled.hpp"
26#include "classfile/classLoaderDataGraph.hpp"
27#include "classfile/metadataOnStackMark.hpp"
28#include "classfile/stringTable.hpp"
29#include "code/codeCache.hpp"
30#include "code/icBuffer.hpp"
31#include "gc/g1/g1Allocator.inline.hpp"
32#include "gc/g1/g1Arguments.hpp"
33#include "gc/g1/g1BarrierSet.hpp"
34#include "gc/g1/g1CollectedHeap.inline.hpp"
35#include "gc/g1/g1CollectionSet.hpp"
36#include "gc/g1/g1CollectorState.hpp"
37#include "gc/g1/g1ConcurrentRefine.hpp"
38#include "gc/g1/g1ConcurrentRefineThread.hpp"
39#include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40#include "gc/g1/g1DirtyCardQueue.hpp"
41#include "gc/g1/g1EvacStats.inline.hpp"
42#include "gc/g1/g1FullCollector.hpp"
43#include "gc/g1/g1GCPhaseTimes.hpp"
44#include "gc/g1/g1HeapSizingPolicy.hpp"
45#include "gc/g1/g1HeapTransition.hpp"
46#include "gc/g1/g1HeapVerifier.hpp"
47#include "gc/g1/g1HotCardCache.hpp"
48#include "gc/g1/g1MemoryPool.hpp"
49#include "gc/g1/g1OopClosures.inline.hpp"
50#include "gc/g1/g1ParScanThreadState.inline.hpp"
51#include "gc/g1/g1Policy.hpp"
52#include "gc/g1/g1RegionToSpaceMapper.hpp"
53#include "gc/g1/g1RemSet.hpp"
54#include "gc/g1/g1RootClosures.hpp"
55#include "gc/g1/g1RootProcessor.hpp"
56#include "gc/g1/g1SATBMarkQueueSet.hpp"
57#include "gc/g1/g1StringDedup.hpp"
58#include "gc/g1/g1ThreadLocalData.hpp"
59#include "gc/g1/g1YCTypes.hpp"
60#include "gc/g1/g1YoungRemSetSamplingThread.hpp"
61#include "gc/g1/g1VMOperations.hpp"
62#include "gc/g1/heapRegion.inline.hpp"
63#include "gc/g1/heapRegionRemSet.hpp"
64#include "gc/g1/heapRegionSet.inline.hpp"
65#include "gc/shared/gcBehaviours.hpp"
66#include "gc/shared/gcHeapSummary.hpp"
67#include "gc/shared/gcId.hpp"
68#include "gc/shared/gcLocker.hpp"
69#include "gc/shared/gcTimer.hpp"
70#include "gc/shared/gcTrace.hpp"
71#include "gc/shared/gcTraceTime.inline.hpp"
72#include "gc/shared/generationSpec.hpp"
73#include "gc/shared/isGCActiveMark.hpp"
74#include "gc/shared/oopStorageParState.hpp"
75#include "gc/shared/parallelCleaning.hpp"
76#include "gc/shared/preservedMarks.inline.hpp"
77#include "gc/shared/suspendibleThreadSet.hpp"
78#include "gc/shared/referenceProcessor.inline.hpp"
79#include "gc/shared/taskqueue.inline.hpp"
80#include "gc/shared/weakProcessor.inline.hpp"
81#include "gc/shared/workerPolicy.hpp"
82#include "logging/log.hpp"
83#include "memory/allocation.hpp"
84#include "memory/iterator.hpp"
85#include "memory/resourceArea.hpp"
86#include "memory/universe.hpp"
87#include "oops/access.inline.hpp"
88#include "oops/compressedOops.inline.hpp"
89#include "oops/oop.inline.hpp"
90#include "runtime/atomic.hpp"
91#include "runtime/flags/flagSetting.hpp"
92#include "runtime/handles.inline.hpp"
93#include "runtime/init.hpp"
94#include "runtime/orderAccess.hpp"
95#include "runtime/threadSMR.hpp"
96#include "runtime/vmThread.hpp"
97#include "utilities/align.hpp"
98#include "utilities/globalDefinitions.hpp"
99#include "utilities/stack.inline.hpp"
100
101size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
102
103// INVARIANTS/NOTES
104//
105// All allocation activity covered by the G1CollectedHeap interface is
106// serialized by acquiring the HeapLock. This happens in mem_allocate
107// and allocate_new_tlab, which are the "entry" points to the
108// allocation code from the rest of the JVM. (Note that this does not
109// apply to TLAB allocation, which is not part of this interface: it
110// is done by clients of this interface.)
111
112class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
113 private:
114 size_t _num_dirtied;
115 G1CollectedHeap* _g1h;
116 G1CardTable* _g1_ct;
117
118 HeapRegion* region_for_card(CardValue* card_ptr) const {
119 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
120 }
121
122 bool will_become_free(HeapRegion* hr) const {
123 // A region will be freed by free_collection_set if the region is in the
124 // collection set and has not had an evacuation failure.
125 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
126 }
127
128 public:
129 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
130 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
131
132 bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
133 HeapRegion* hr = region_for_card(card_ptr);
134
135 // Should only dirty cards in regions that won't be freed.
136 if (!will_become_free(hr)) {
137 *card_ptr = G1CardTable::dirty_card_val();
138 _num_dirtied++;
139 }
140
141 return true;
142 }
143
144 size_t num_dirtied() const { return _num_dirtied; }
145};
146
147
148void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
149 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
150}
151
152void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
153 // The from card cache is not the memory that is actually committed. So we cannot
154 // take advantage of the zero_filled parameter.
155 reset_from_card_cache(start_idx, num_regions);
156}
157
158Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
159 Ticks start = Ticks::now();
160 workers()->run_task(task, workers()->active_workers());
161 return Ticks::now() - start;
162}
163
164HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
165 MemRegion mr) {
166 return new HeapRegion(hrs_index, bot(), mr);
167}
168
169// Private methods.
170
171HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
172 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
173 "the only time we use this to allocate a humongous region is "
174 "when we are allocating a single humongous region");
175
176 HeapRegion* res = _hrm->allocate_free_region(type);
177
178 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
179 // Currently, only attempts to allocate GC alloc regions set
180 // do_expand to true. So, we should only reach here during a
181 // safepoint. If this assumption changes we might have to
182 // reconsider the use of _expand_heap_after_alloc_failure.
183 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
184
185 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
186 word_size * HeapWordSize);
187
188 if (expand(word_size * HeapWordSize)) {
189 // Given that expand() succeeded in expanding the heap, and we
190 // always expand the heap by an amount aligned to the heap
191 // region size, the free list should in theory not be empty.
192 // In either case allocate_free_region() will check for NULL.
193 res = _hrm->allocate_free_region(type);
194 } else {
195 _expand_heap_after_alloc_failure = false;
196 }
197 }
198 return res;
199}
200
201HeapWord*
202G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
203 uint num_regions,
204 size_t word_size) {
205 assert(first != G1_NO_HRM_INDEX, "pre-condition");
206 assert(is_humongous(word_size), "word_size should be humongous");
207 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
208
209 // Index of last region in the series.
210 uint last = first + num_regions - 1;
211
212 // We need to initialize the region(s) we just discovered. This is
213 // a bit tricky given that it can happen concurrently with
214 // refinement threads refining cards on these regions and
215 // potentially wanting to refine the BOT as they are scanning
216 // those cards (this can happen shortly after a cleanup; see CR
217 // 6991377). So we have to set up the region(s) carefully and in
218 // a specific order.
219
220 // The word size sum of all the regions we will allocate.
221 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
222 assert(word_size <= word_size_sum, "sanity");
223
224 // This will be the "starts humongous" region.
225 HeapRegion* first_hr = region_at(first);
226 // The header of the new object will be placed at the bottom of
227 // the first region.
228 HeapWord* new_obj = first_hr->bottom();
229 // This will be the new top of the new object.
230 HeapWord* obj_top = new_obj + word_size;
231
232 // First, we need to zero the header of the space that we will be
233 // allocating. When we update top further down, some refinement
234 // threads might try to scan the region. By zeroing the header we
235 // ensure that any thread that will try to scan the region will
236 // come across the zero klass word and bail out.
237 //
238 // NOTE: It would not have been correct to have used
239 // CollectedHeap::fill_with_object() and make the space look like
240 // an int array. The thread that is doing the allocation will
241 // later update the object header to a potentially different array
242 // type and, for a very short period of time, the klass and length
243 // fields will be inconsistent. This could cause a refinement
244 // thread to calculate the object size incorrectly.
245 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
246
247 // Next, pad out the unused tail of the last region with filler
248 // objects, for improved usage accounting.
249 // How many words we use for filler objects.
250 size_t word_fill_size = word_size_sum - word_size;
251
252 // How many words memory we "waste" which cannot hold a filler object.
253 size_t words_not_fillable = 0;
254
255 if (word_fill_size >= min_fill_size()) {
256 fill_with_objects(obj_top, word_fill_size);
257 } else if (word_fill_size > 0) {
258 // We have space to fill, but we cannot fit an object there.
259 words_not_fillable = word_fill_size;
260 word_fill_size = 0;
261 }
262
263 // We will set up the first region as "starts humongous". This
264 // will also update the BOT covering all the regions to reflect
265 // that there is a single object that starts at the bottom of the
266 // first region.
267 first_hr->set_starts_humongous(obj_top, word_fill_size);
268 _policy->remset_tracker()->update_at_allocate(first_hr);
269 // Then, if there are any, we will set up the "continues
270 // humongous" regions.
271 HeapRegion* hr = NULL;
272 for (uint i = first + 1; i <= last; ++i) {
273 hr = region_at(i);
274 hr->set_continues_humongous(first_hr);
275 _policy->remset_tracker()->update_at_allocate(hr);
276 }
277
278 // Up to this point no concurrent thread would have been able to
279 // do any scanning on any region in this series. All the top
280 // fields still point to bottom, so the intersection between
281 // [bottom,top] and [card_start,card_end] will be empty. Before we
282 // update the top fields, we'll do a storestore to make sure that
283 // no thread sees the update to top before the zeroing of the
284 // object header and the BOT initialization.
285 OrderAccess::storestore();
286
287 // Now, we will update the top fields of the "continues humongous"
288 // regions except the last one.
289 for (uint i = first; i < last; ++i) {
290 hr = region_at(i);
291 hr->set_top(hr->end());
292 }
293
294 hr = region_at(last);
295 // If we cannot fit a filler object, we must set top to the end
296 // of the humongous object, otherwise we cannot iterate the heap
297 // and the BOT will not be complete.
298 hr->set_top(hr->end() - words_not_fillable);
299
300 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
301 "obj_top should be in last region");
302
303 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
304
305 assert(words_not_fillable == 0 ||
306 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
307 "Miscalculation in humongous allocation");
308
309 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
310
311 for (uint i = first; i <= last; ++i) {
312 hr = region_at(i);
313 _humongous_set.add(hr);
314 _hr_printer.alloc(hr);
315 }
316
317 return new_obj;
318}
319
320size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
321 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
322 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
323}
324
325// If could fit into free regions w/o expansion, try.
326// Otherwise, if can expand, do so.
327// Otherwise, if using ex regions might help, try with ex given back.
328HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
329 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
330
331 _verifier->verify_region_sets_optional();
332
333 uint first = G1_NO_HRM_INDEX;
334 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
335
336 if (obj_regions == 1) {
337 // Only one region to allocate, try to use a fast path by directly allocating
338 // from the free lists. Do not try to expand here, we will potentially do that
339 // later.
340 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
341 if (hr != NULL) {
342 first = hr->hrm_index();
343 }
344 } else {
345 // Policy: Try only empty regions (i.e. already committed first). Maybe we
346 // are lucky enough to find some.
347 first = _hrm->find_contiguous_only_empty(obj_regions);
348 if (first != G1_NO_HRM_INDEX) {
349 _hrm->allocate_free_regions_starting_at(first, obj_regions);
350 }
351 }
352
353 if (first == G1_NO_HRM_INDEX) {
354 // Policy: We could not find enough regions for the humongous object in the
355 // free list. Look through the heap to find a mix of free and uncommitted regions.
356 // If so, try expansion.
357 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
358 if (first != G1_NO_HRM_INDEX) {
359 // We found something. Make sure these regions are committed, i.e. expand
360 // the heap. Alternatively we could do a defragmentation GC.
361 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
362 word_size * HeapWordSize);
363
364 _hrm->expand_at(first, obj_regions, workers());
365 policy()->record_new_heap_size(num_regions());
366
367#ifdef ASSERT
368 for (uint i = first; i < first + obj_regions; ++i) {
369 HeapRegion* hr = region_at(i);
370 assert(hr->is_free(), "sanity");
371 assert(hr->is_empty(), "sanity");
372 assert(is_on_master_free_list(hr), "sanity");
373 }
374#endif
375 _hrm->allocate_free_regions_starting_at(first, obj_regions);
376 } else {
377 // Policy: Potentially trigger a defragmentation GC.
378 }
379 }
380
381 HeapWord* result = NULL;
382 if (first != G1_NO_HRM_INDEX) {
383 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
384 assert(result != NULL, "it should always return a valid result");
385
386 // A successful humongous object allocation changes the used space
387 // information of the old generation so we need to recalculate the
388 // sizes and update the jstat counters here.
389 g1mm()->update_sizes();
390 }
391
392 _verifier->verify_region_sets_optional();
393
394 return result;
395}
396
397HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
398 size_t requested_size,
399 size_t* actual_size) {
400 assert_heap_not_locked_and_not_at_safepoint();
401 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
402
403 return attempt_allocation(min_size, requested_size, actual_size);
404}
405
406HeapWord*
407G1CollectedHeap::mem_allocate(size_t word_size,
408 bool* gc_overhead_limit_was_exceeded) {
409 assert_heap_not_locked_and_not_at_safepoint();
410
411 if (is_humongous(word_size)) {
412 return attempt_allocation_humongous(word_size);
413 }
414 size_t dummy = 0;
415 return attempt_allocation(word_size, word_size, &dummy);
416}
417
418HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
419 ResourceMark rm; // For retrieving the thread names in log messages.
420
421 // Make sure you read the note in attempt_allocation_humongous().
422
423 assert_heap_not_locked_and_not_at_safepoint();
424 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
425 "be called for humongous allocation requests");
426
427 // We should only get here after the first-level allocation attempt
428 // (attempt_allocation()) failed to allocate.
429
430 // We will loop until a) we manage to successfully perform the
431 // allocation or b) we successfully schedule a collection which
432 // fails to perform the allocation. b) is the only case when we'll
433 // return NULL.
434 HeapWord* result = NULL;
435 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
436 bool should_try_gc;
437 uint gc_count_before;
438
439 {
440 MutexLocker x(Heap_lock);
441 result = _allocator->attempt_allocation_locked(word_size);
442 if (result != NULL) {
443 return result;
444 }
445
446 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
447 // This is different to when only GCLocker::needs_gc() is set: try to avoid
448 // waiting because the GCLocker is active to not wait too long.
449 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
450 // No need for an ergo message here, can_expand_young_list() does this when
451 // it returns true.
452 result = _allocator->attempt_allocation_force(word_size);
453 if (result != NULL) {
454 return result;
455 }
456 }
457 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
458 // the GCLocker initiated GC has been performed and then retry. This includes
459 // the case when the GC Locker is not active but has not been performed.
460 should_try_gc = !GCLocker::needs_gc();
461 // Read the GC count while still holding the Heap_lock.
462 gc_count_before = total_collections();
463 }
464
465 if (should_try_gc) {
466 bool succeeded;
467 result = do_collection_pause(word_size, gc_count_before, &succeeded,
468 GCCause::_g1_inc_collection_pause);
469 if (result != NULL) {
470 assert(succeeded, "only way to get back a non-NULL result");
471 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
472 Thread::current()->name(), p2i(result));
473 return result;
474 }
475
476 if (succeeded) {
477 // We successfully scheduled a collection which failed to allocate. No
478 // point in trying to allocate further. We'll just return NULL.
479 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
480 SIZE_FORMAT " words", Thread::current()->name(), word_size);
481 return NULL;
482 }
483 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
484 Thread::current()->name(), word_size);
485 } else {
486 // Failed to schedule a collection.
487 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
488 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
489 SIZE_FORMAT " words", Thread::current()->name(), word_size);
490 return NULL;
491 }
492 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
493 // The GCLocker is either active or the GCLocker initiated
494 // GC has not yet been performed. Stall until it is and
495 // then retry the allocation.
496 GCLocker::stall_until_clear();
497 gclocker_retry_count += 1;
498 }
499
500 // We can reach here if we were unsuccessful in scheduling a
501 // collection (because another thread beat us to it) or if we were
502 // stalled due to the GC locker. In either can we should retry the
503 // allocation attempt in case another thread successfully
504 // performed a collection and reclaimed enough space. We do the
505 // first attempt (without holding the Heap_lock) here and the
506 // follow-on attempt will be at the start of the next loop
507 // iteration (after taking the Heap_lock).
508 size_t dummy = 0;
509 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
510 if (result != NULL) {
511 return result;
512 }
513
514 // Give a warning if we seem to be looping forever.
515 if ((QueuedAllocationWarningCount > 0) &&
516 (try_count % QueuedAllocationWarningCount == 0)) {
517 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
518 Thread::current()->name(), try_count, word_size);
519 }
520 }
521
522 ShouldNotReachHere();
523 return NULL;
524}
525
526void G1CollectedHeap::begin_archive_alloc_range(bool open) {
527 assert_at_safepoint_on_vm_thread();
528 if (_archive_allocator == NULL) {
529 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
530 }
531}
532
533bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
534 // Allocations in archive regions cannot be of a size that would be considered
535 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
536 // may be different at archive-restore time.
537 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
538}
539
540HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
541 assert_at_safepoint_on_vm_thread();
542 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
543 if (is_archive_alloc_too_large(word_size)) {
544 return NULL;
545 }
546 return _archive_allocator->archive_mem_allocate(word_size);
547}
548
549void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
550 size_t end_alignment_in_bytes) {
551 assert_at_safepoint_on_vm_thread();
552 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
553
554 // Call complete_archive to do the real work, filling in the MemRegion
555 // array with the archive regions.
556 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
557 delete _archive_allocator;
558 _archive_allocator = NULL;
559}
560
561bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
562 assert(ranges != NULL, "MemRegion array NULL");
563 assert(count != 0, "No MemRegions provided");
564 MemRegion reserved = _hrm->reserved();
565 for (size_t i = 0; i < count; i++) {
566 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
567 return false;
568 }
569 }
570 return true;
571}
572
573bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
574 size_t count,
575 bool open) {
576 assert(!is_init_completed(), "Expect to be called at JVM init time");
577 assert(ranges != NULL, "MemRegion array NULL");
578 assert(count != 0, "No MemRegions provided");
579 MutexLocker x(Heap_lock);
580
581 MemRegion reserved = _hrm->reserved();
582 HeapWord* prev_last_addr = NULL;
583 HeapRegion* prev_last_region = NULL;
584
585 // Temporarily disable pretouching of heap pages. This interface is used
586 // when mmap'ing archived heap data in, so pre-touching is wasted.
587 FlagSetting fs(AlwaysPreTouch, false);
588
589 // Enable archive object checking used by G1MarkSweep. We have to let it know
590 // about each archive range, so that objects in those ranges aren't marked.
591 G1ArchiveAllocator::enable_archive_object_check();
592
593 // For each specified MemRegion range, allocate the corresponding G1
594 // regions and mark them as archive regions. We expect the ranges
595 // in ascending starting address order, without overlap.
596 for (size_t i = 0; i < count; i++) {
597 MemRegion curr_range = ranges[i];
598 HeapWord* start_address = curr_range.start();
599 size_t word_size = curr_range.word_size();
600 HeapWord* last_address = curr_range.last();
601 size_t commits = 0;
602
603 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
604 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
605 p2i(start_address), p2i(last_address));
606 guarantee(start_address > prev_last_addr,
607 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
608 p2i(start_address), p2i(prev_last_addr));
609 prev_last_addr = last_address;
610
611 // Check for ranges that start in the same G1 region in which the previous
612 // range ended, and adjust the start address so we don't try to allocate
613 // the same region again. If the current range is entirely within that
614 // region, skip it, just adjusting the recorded top.
615 HeapRegion* start_region = _hrm->addr_to_region(start_address);
616 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
617 start_address = start_region->end();
618 if (start_address > last_address) {
619 increase_used(word_size * HeapWordSize);
620 start_region->set_top(last_address + 1);
621 continue;
622 }
623 start_region->set_top(start_address);
624 curr_range = MemRegion(start_address, last_address + 1);
625 start_region = _hrm->addr_to_region(start_address);
626 }
627
628 // Perform the actual region allocation, exiting if it fails.
629 // Then note how much new space we have allocated.
630 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
631 return false;
632 }
633 increase_used(word_size * HeapWordSize);
634 if (commits != 0) {
635 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
636 HeapRegion::GrainWords * HeapWordSize * commits);
637
638 }
639
640 // Mark each G1 region touched by the range as archive, add it to
641 // the old set, and set top.
642 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
643 HeapRegion* last_region = _hrm->addr_to_region(last_address);
644 prev_last_region = last_region;
645
646 while (curr_region != NULL) {
647 assert(curr_region->is_empty() && !curr_region->is_pinned(),
648 "Region already in use (index %u)", curr_region->hrm_index());
649 if (open) {
650 curr_region->set_open_archive();
651 } else {
652 curr_region->set_closed_archive();
653 }
654 _hr_printer.alloc(curr_region);
655 _archive_set.add(curr_region);
656 HeapWord* top;
657 HeapRegion* next_region;
658 if (curr_region != last_region) {
659 top = curr_region->end();
660 next_region = _hrm->next_region_in_heap(curr_region);
661 } else {
662 top = last_address + 1;
663 next_region = NULL;
664 }
665 curr_region->set_top(top);
666 curr_region->set_first_dead(top);
667 curr_region->set_end_of_live(top);
668 curr_region = next_region;
669 }
670
671 // Notify mark-sweep of the archive
672 G1ArchiveAllocator::set_range_archive(curr_range, open);
673 }
674 return true;
675}
676
677void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
678 assert(!is_init_completed(), "Expect to be called at JVM init time");
679 assert(ranges != NULL, "MemRegion array NULL");
680 assert(count != 0, "No MemRegions provided");
681 MemRegion reserved = _hrm->reserved();
682 HeapWord *prev_last_addr = NULL;
683 HeapRegion* prev_last_region = NULL;
684
685 // For each MemRegion, create filler objects, if needed, in the G1 regions
686 // that contain the address range. The address range actually within the
687 // MemRegion will not be modified. That is assumed to have been initialized
688 // elsewhere, probably via an mmap of archived heap data.
689 MutexLocker x(Heap_lock);
690 for (size_t i = 0; i < count; i++) {
691 HeapWord* start_address = ranges[i].start();
692 HeapWord* last_address = ranges[i].last();
693
694 assert(reserved.contains(start_address) && reserved.contains(last_address),
695 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
696 p2i(start_address), p2i(last_address));
697 assert(start_address > prev_last_addr,
698 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
699 p2i(start_address), p2i(prev_last_addr));
700
701 HeapRegion* start_region = _hrm->addr_to_region(start_address);
702 HeapRegion* last_region = _hrm->addr_to_region(last_address);
703 HeapWord* bottom_address = start_region->bottom();
704
705 // Check for a range beginning in the same region in which the
706 // previous one ended.
707 if (start_region == prev_last_region) {
708 bottom_address = prev_last_addr + 1;
709 }
710
711 // Verify that the regions were all marked as archive regions by
712 // alloc_archive_regions.
713 HeapRegion* curr_region = start_region;
714 while (curr_region != NULL) {
715 guarantee(curr_region->is_archive(),
716 "Expected archive region at index %u", curr_region->hrm_index());
717 if (curr_region != last_region) {
718 curr_region = _hrm->next_region_in_heap(curr_region);
719 } else {
720 curr_region = NULL;
721 }
722 }
723
724 prev_last_addr = last_address;
725 prev_last_region = last_region;
726
727 // Fill the memory below the allocated range with dummy object(s),
728 // if the region bottom does not match the range start, or if the previous
729 // range ended within the same G1 region, and there is a gap.
730 if (start_address != bottom_address) {
731 size_t fill_size = pointer_delta(start_address, bottom_address);
732 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
733 increase_used(fill_size * HeapWordSize);
734 }
735 }
736}
737
738inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
739 size_t desired_word_size,
740 size_t* actual_word_size) {
741 assert_heap_not_locked_and_not_at_safepoint();
742 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
743 "be called for humongous allocation requests");
744
745 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
746
747 if (result == NULL) {
748 *actual_word_size = desired_word_size;
749 result = attempt_allocation_slow(desired_word_size);
750 }
751
752 assert_heap_not_locked();
753 if (result != NULL) {
754 assert(*actual_word_size != 0, "Actual size must have been set here");
755 dirty_young_block(result, *actual_word_size);
756 } else {
757 *actual_word_size = 0;
758 }
759
760 return result;
761}
762
763void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
764 assert(!is_init_completed(), "Expect to be called at JVM init time");
765 assert(ranges != NULL, "MemRegion array NULL");
766 assert(count != 0, "No MemRegions provided");
767 MemRegion reserved = _hrm->reserved();
768 HeapWord* prev_last_addr = NULL;
769 HeapRegion* prev_last_region = NULL;
770 size_t size_used = 0;
771 size_t uncommitted_regions = 0;
772
773 // For each Memregion, free the G1 regions that constitute it, and
774 // notify mark-sweep that the range is no longer to be considered 'archive.'
775 MutexLocker x(Heap_lock);
776 for (size_t i = 0; i < count; i++) {
777 HeapWord* start_address = ranges[i].start();
778 HeapWord* last_address = ranges[i].last();
779
780 assert(reserved.contains(start_address) && reserved.contains(last_address),
781 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
782 p2i(start_address), p2i(last_address));
783 assert(start_address > prev_last_addr,
784 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
785 p2i(start_address), p2i(prev_last_addr));
786 size_used += ranges[i].byte_size();
787 prev_last_addr = last_address;
788
789 HeapRegion* start_region = _hrm->addr_to_region(start_address);
790 HeapRegion* last_region = _hrm->addr_to_region(last_address);
791
792 // Check for ranges that start in the same G1 region in which the previous
793 // range ended, and adjust the start address so we don't try to free
794 // the same region again. If the current range is entirely within that
795 // region, skip it.
796 if (start_region == prev_last_region) {
797 start_address = start_region->end();
798 if (start_address > last_address) {
799 continue;
800 }
801 start_region = _hrm->addr_to_region(start_address);
802 }
803 prev_last_region = last_region;
804
805 // After verifying that each region was marked as an archive region by
806 // alloc_archive_regions, set it free and empty and uncommit it.
807 HeapRegion* curr_region = start_region;
808 while (curr_region != NULL) {
809 guarantee(curr_region->is_archive(),
810 "Expected archive region at index %u", curr_region->hrm_index());
811 uint curr_index = curr_region->hrm_index();
812 _archive_set.remove(curr_region);
813 curr_region->set_free();
814 curr_region->set_top(curr_region->bottom());
815 if (curr_region != last_region) {
816 curr_region = _hrm->next_region_in_heap(curr_region);
817 } else {
818 curr_region = NULL;
819 }
820 _hrm->shrink_at(curr_index, 1);
821 uncommitted_regions++;
822 }
823
824 // Notify mark-sweep that this is no longer an archive range.
825 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
826 }
827
828 if (uncommitted_regions != 0) {
829 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
830 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
831 }
832 decrease_used(size_used);
833}
834
835oop G1CollectedHeap::materialize_archived_object(oop obj) {
836 assert(obj != NULL, "archived obj is NULL");
837 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
838
839 // Loading an archived object makes it strongly reachable. If it is
840 // loaded during concurrent marking, it must be enqueued to the SATB
841 // queue, shading the previously white object gray.
842 G1BarrierSet::enqueue(obj);
843
844 return obj;
845}
846
847HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
848 ResourceMark rm; // For retrieving the thread names in log messages.
849
850 // The structure of this method has a lot of similarities to
851 // attempt_allocation_slow(). The reason these two were not merged
852 // into a single one is that such a method would require several "if
853 // allocation is not humongous do this, otherwise do that"
854 // conditional paths which would obscure its flow. In fact, an early
855 // version of this code did use a unified method which was harder to
856 // follow and, as a result, it had subtle bugs that were hard to
857 // track down. So keeping these two methods separate allows each to
858 // be more readable. It will be good to keep these two in sync as
859 // much as possible.
860
861 assert_heap_not_locked_and_not_at_safepoint();
862 assert(is_humongous(word_size), "attempt_allocation_humongous() "
863 "should only be called for humongous allocations");
864
865 // Humongous objects can exhaust the heap quickly, so we should check if we
866 // need to start a marking cycle at each humongous object allocation. We do
867 // the check before we do the actual allocation. The reason for doing it
868 // before the allocation is that we avoid having to keep track of the newly
869 // allocated memory while we do a GC.
870 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
871 word_size)) {
872 collect(GCCause::_g1_humongous_allocation);
873 }
874
875 // We will loop until a) we manage to successfully perform the
876 // allocation or b) we successfully schedule a collection which
877 // fails to perform the allocation. b) is the only case when we'll
878 // return NULL.
879 HeapWord* result = NULL;
880 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
881 bool should_try_gc;
882 uint gc_count_before;
883
884
885 {
886 MutexLocker x(Heap_lock);
887
888 // Given that humongous objects are not allocated in young
889 // regions, we'll first try to do the allocation without doing a
890 // collection hoping that there's enough space in the heap.
891 result = humongous_obj_allocate(word_size);
892 if (result != NULL) {
893 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
894 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
895 return result;
896 }
897
898 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
899 // the GCLocker initiated GC has been performed and then retry. This includes
900 // the case when the GC Locker is not active but has not been performed.
901 should_try_gc = !GCLocker::needs_gc();
902 // Read the GC count while still holding the Heap_lock.
903 gc_count_before = total_collections();
904 }
905
906 if (should_try_gc) {
907 bool succeeded;
908 result = do_collection_pause(word_size, gc_count_before, &succeeded,
909 GCCause::_g1_humongous_allocation);
910 if (result != NULL) {
911 assert(succeeded, "only way to get back a non-NULL result");
912 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
913 Thread::current()->name(), p2i(result));
914 return result;
915 }
916
917 if (succeeded) {
918 // We successfully scheduled a collection which failed to allocate. No
919 // point in trying to allocate further. We'll just return NULL.
920 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
921 SIZE_FORMAT " words", Thread::current()->name(), word_size);
922 return NULL;
923 }
924 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
925 Thread::current()->name(), word_size);
926 } else {
927 // Failed to schedule a collection.
928 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
929 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
930 SIZE_FORMAT " words", Thread::current()->name(), word_size);
931 return NULL;
932 }
933 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
934 // The GCLocker is either active or the GCLocker initiated
935 // GC has not yet been performed. Stall until it is and
936 // then retry the allocation.
937 GCLocker::stall_until_clear();
938 gclocker_retry_count += 1;
939 }
940
941
942 // We can reach here if we were unsuccessful in scheduling a
943 // collection (because another thread beat us to it) or if we were
944 // stalled due to the GC locker. In either can we should retry the
945 // allocation attempt in case another thread successfully
946 // performed a collection and reclaimed enough space.
947 // Humongous object allocation always needs a lock, so we wait for the retry
948 // in the next iteration of the loop, unlike for the regular iteration case.
949 // Give a warning if we seem to be looping forever.
950
951 if ((QueuedAllocationWarningCount > 0) &&
952 (try_count % QueuedAllocationWarningCount == 0)) {
953 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
954 Thread::current()->name(), try_count, word_size);
955 }
956 }
957
958 ShouldNotReachHere();
959 return NULL;
960}
961
962HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
963 bool expect_null_mutator_alloc_region) {
964 assert_at_safepoint_on_vm_thread();
965 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
966 "the current alloc region was unexpectedly found to be non-NULL");
967
968 if (!is_humongous(word_size)) {
969 return _allocator->attempt_allocation_locked(word_size);
970 } else {
971 HeapWord* result = humongous_obj_allocate(word_size);
972 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
973 collector_state()->set_initiate_conc_mark_if_possible(true);
974 }
975 return result;
976 }
977
978 ShouldNotReachHere();
979}
980
981class PostCompactionPrinterClosure: public HeapRegionClosure {
982private:
983 G1HRPrinter* _hr_printer;
984public:
985 bool do_heap_region(HeapRegion* hr) {
986 assert(!hr->is_young(), "not expecting to find young regions");
987 _hr_printer->post_compaction(hr);
988 return false;
989 }
990
991 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
992 : _hr_printer(hr_printer) { }
993};
994
995void G1CollectedHeap::print_hrm_post_compaction() {
996 if (_hr_printer.is_active()) {
997 PostCompactionPrinterClosure cl(hr_printer());
998 heap_region_iterate(&cl);
999 }
1000}
1001
1002void G1CollectedHeap::abort_concurrent_cycle() {
1003 // If we start the compaction before the CM threads finish
1004 // scanning the root regions we might trip them over as we'll
1005 // be moving objects / updating references. So let's wait until
1006 // they are done. By telling them to abort, they should complete
1007 // early.
1008 _cm->root_regions()->abort();
1009 _cm->root_regions()->wait_until_scan_finished();
1010
1011 // Disable discovery and empty the discovered lists
1012 // for the CM ref processor.
1013 _ref_processor_cm->disable_discovery();
1014 _ref_processor_cm->abandon_partial_discovery();
1015 _ref_processor_cm->verify_no_references_recorded();
1016
1017 // Abandon current iterations of concurrent marking and concurrent
1018 // refinement, if any are in progress.
1019 concurrent_mark()->concurrent_cycle_abort();
1020}
1021
1022void G1CollectedHeap::prepare_heap_for_full_collection() {
1023 // Make sure we'll choose a new allocation region afterwards.
1024 _allocator->release_mutator_alloc_region();
1025 _allocator->abandon_gc_alloc_regions();
1026
1027 // We may have added regions to the current incremental collection
1028 // set between the last GC or pause and now. We need to clear the
1029 // incremental collection set and then start rebuilding it afresh
1030 // after this full GC.
1031 abandon_collection_set(collection_set());
1032
1033 tear_down_region_sets(false /* free_list_only */);
1034
1035 hrm()->prepare_for_full_collection_start();
1036}
1037
1038void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1039 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1040 assert_used_and_recalculate_used_equal(this);
1041 _verifier->verify_region_sets_optional();
1042 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1043 _verifier->check_bitmaps("Full GC Start");
1044}
1045
1046void G1CollectedHeap::prepare_heap_for_mutators() {
1047 hrm()->prepare_for_full_collection_end();
1048
1049 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1050 ClassLoaderDataGraph::purge();
1051 MetaspaceUtils::verify_metrics();
1052
1053 // Prepare heap for normal collections.
1054 assert(num_free_regions() == 0, "we should not have added any free regions");
1055 rebuild_region_sets(false /* free_list_only */);
1056 abort_refinement();
1057 resize_heap_if_necessary();
1058
1059 // Rebuild the strong code root lists for each region
1060 rebuild_strong_code_roots();
1061
1062 // Purge code root memory
1063 purge_code_root_memory();
1064
1065 // Start a new incremental collection set for the next pause
1066 start_new_collection_set();
1067
1068 _allocator->init_mutator_alloc_region();
1069
1070 // Post collection state updates.
1071 MetaspaceGC::compute_new_size();
1072}
1073
1074void G1CollectedHeap::abort_refinement() {
1075 if (_hot_card_cache->use_cache()) {
1076 _hot_card_cache->reset_hot_cache();
1077 }
1078
1079 // Discard all remembered set updates.
1080 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1081 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1082}
1083
1084void G1CollectedHeap::verify_after_full_collection() {
1085 _hrm->verify_optional();
1086 _verifier->verify_region_sets_optional();
1087 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1088 // Clear the previous marking bitmap, if needed for bitmap verification.
1089 // Note we cannot do this when we clear the next marking bitmap in
1090 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1091 // objects marked during a full GC against the previous bitmap.
1092 // But we need to clear it before calling check_bitmaps below since
1093 // the full GC has compacted objects and updated TAMS but not updated
1094 // the prev bitmap.
1095 if (G1VerifyBitmaps) {
1096 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1097 _cm->clear_prev_bitmap(workers());
1098 }
1099 // This call implicitly verifies that the next bitmap is clear after Full GC.
1100 _verifier->check_bitmaps("Full GC End");
1101
1102 // At this point there should be no regions in the
1103 // entire heap tagged as young.
1104 assert(check_young_list_empty(), "young list should be empty at this point");
1105
1106 // Note: since we've just done a full GC, concurrent
1107 // marking is no longer active. Therefore we need not
1108 // re-enable reference discovery for the CM ref processor.
1109 // That will be done at the start of the next marking cycle.
1110 // We also know that the STW processor should no longer
1111 // discover any new references.
1112 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1113 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1114 _ref_processor_stw->verify_no_references_recorded();
1115 _ref_processor_cm->verify_no_references_recorded();
1116}
1117
1118void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1119 // Post collection logging.
1120 // We should do this after we potentially resize the heap so
1121 // that all the COMMIT / UNCOMMIT events are generated before
1122 // the compaction events.
1123 print_hrm_post_compaction();
1124 heap_transition->print();
1125 print_heap_after_gc();
1126 print_heap_regions();
1127#ifdef TRACESPINNING
1128 ParallelTaskTerminator::print_termination_counts();
1129#endif
1130}
1131
1132bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1133 bool clear_all_soft_refs) {
1134 assert_at_safepoint_on_vm_thread();
1135
1136 if (GCLocker::check_active_before_gc()) {
1137 // Full GC was not completed.
1138 return false;
1139 }
1140
1141 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1142 soft_ref_policy()->should_clear_all_soft_refs();
1143
1144 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1145 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1146
1147 collector.prepare_collection();
1148 collector.collect();
1149 collector.complete_collection();
1150
1151 // Full collection was successfully completed.
1152 return true;
1153}
1154
1155void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1156 // Currently, there is no facility in the do_full_collection(bool) API to notify
1157 // the caller that the collection did not succeed (e.g., because it was locked
1158 // out by the GC locker). So, right now, we'll ignore the return value.
1159 bool dummy = do_full_collection(true, /* explicit_gc */
1160 clear_all_soft_refs);
1161}
1162
1163void G1CollectedHeap::resize_heap_if_necessary() {
1164 assert_at_safepoint_on_vm_thread();
1165
1166 // Capacity, free and used after the GC counted as full regions to
1167 // include the waste in the following calculations.
1168 const size_t capacity_after_gc = capacity();
1169 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1170
1171 // This is enforced in arguments.cpp.
1172 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1173 "otherwise the code below doesn't make sense");
1174
1175 // We don't have floating point command-line arguments
1176 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1177 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1178 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1179 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1180
1181 // We have to be careful here as these two calculations can overflow
1182 // 32-bit size_t's.
1183 double used_after_gc_d = (double) used_after_gc;
1184 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1185 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1186
1187 // Let's make sure that they are both under the max heap size, which
1188 // by default will make them fit into a size_t.
1189 double desired_capacity_upper_bound = (double) MaxHeapSize;
1190 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1191 desired_capacity_upper_bound);
1192 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1193 desired_capacity_upper_bound);
1194
1195 // We can now safely turn them into size_t's.
1196 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1197 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1198
1199 // This assert only makes sense here, before we adjust them
1200 // with respect to the min and max heap size.
1201 assert(minimum_desired_capacity <= maximum_desired_capacity,
1202 "minimum_desired_capacity = " SIZE_FORMAT ", "
1203 "maximum_desired_capacity = " SIZE_FORMAT,
1204 minimum_desired_capacity, maximum_desired_capacity);
1205
1206 // Should not be greater than the heap max size. No need to adjust
1207 // it with respect to the heap min size as it's a lower bound (i.e.,
1208 // we'll try to make the capacity larger than it, not smaller).
1209 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1210 // Should not be less than the heap min size. No need to adjust it
1211 // with respect to the heap max size as it's an upper bound (i.e.,
1212 // we'll try to make the capacity smaller than it, not greater).
1213 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1214
1215 if (capacity_after_gc < minimum_desired_capacity) {
1216 // Don't expand unless it's significant
1217 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1218
1219 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1220 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1221 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1222 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1223
1224 expand(expand_bytes, _workers);
1225
1226 // No expansion, now see if we want to shrink
1227 } else if (capacity_after_gc > maximum_desired_capacity) {
1228 // Capacity too large, compute shrinking size
1229 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1230
1231 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1232 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1233 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1234 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1235
1236 shrink(shrink_bytes);
1237 }
1238}
1239
1240HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1241 bool do_gc,
1242 bool clear_all_soft_refs,
1243 bool expect_null_mutator_alloc_region,
1244 bool* gc_succeeded) {
1245 *gc_succeeded = true;
1246 // Let's attempt the allocation first.
1247 HeapWord* result =
1248 attempt_allocation_at_safepoint(word_size,
1249 expect_null_mutator_alloc_region);
1250 if (result != NULL) {
1251 return result;
1252 }
1253
1254 // In a G1 heap, we're supposed to keep allocation from failing by
1255 // incremental pauses. Therefore, at least for now, we'll favor
1256 // expansion over collection. (This might change in the future if we can
1257 // do something smarter than full collection to satisfy a failed alloc.)
1258 result = expand_and_allocate(word_size);
1259 if (result != NULL) {
1260 return result;
1261 }
1262
1263 if (do_gc) {
1264 // Expansion didn't work, we'll try to do a Full GC.
1265 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1266 clear_all_soft_refs);
1267 }
1268
1269 return NULL;
1270}
1271
1272HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1273 bool* succeeded) {
1274 assert_at_safepoint_on_vm_thread();
1275
1276 // Attempts to allocate followed by Full GC.
1277 HeapWord* result =
1278 satisfy_failed_allocation_helper(word_size,
1279 true, /* do_gc */
1280 false, /* clear_all_soft_refs */
1281 false, /* expect_null_mutator_alloc_region */
1282 succeeded);
1283
1284 if (result != NULL || !*succeeded) {
1285 return result;
1286 }
1287
1288 // Attempts to allocate followed by Full GC that will collect all soft references.
1289 result = satisfy_failed_allocation_helper(word_size,
1290 true, /* do_gc */
1291 true, /* clear_all_soft_refs */
1292 true, /* expect_null_mutator_alloc_region */
1293 succeeded);
1294
1295 if (result != NULL || !*succeeded) {
1296 return result;
1297 }
1298
1299 // Attempts to allocate, no GC
1300 result = satisfy_failed_allocation_helper(word_size,
1301 false, /* do_gc */
1302 false, /* clear_all_soft_refs */
1303 true, /* expect_null_mutator_alloc_region */
1304 succeeded);
1305
1306 if (result != NULL) {
1307 return result;
1308 }
1309
1310 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1311 "Flag should have been handled and cleared prior to this point");
1312
1313 // What else? We might try synchronous finalization later. If the total
1314 // space available is large enough for the allocation, then a more
1315 // complete compaction phase than we've tried so far might be
1316 // appropriate.
1317 return NULL;
1318}
1319
1320// Attempting to expand the heap sufficiently
1321// to support an allocation of the given "word_size". If
1322// successful, perform the allocation and return the address of the
1323// allocated block, or else "NULL".
1324
1325HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1326 assert_at_safepoint_on_vm_thread();
1327
1328 _verifier->verify_region_sets_optional();
1329
1330 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1331 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1332 word_size * HeapWordSize);
1333
1334
1335 if (expand(expand_bytes, _workers)) {
1336 _hrm->verify_optional();
1337 _verifier->verify_region_sets_optional();
1338 return attempt_allocation_at_safepoint(word_size,
1339 false /* expect_null_mutator_alloc_region */);
1340 }
1341 return NULL;
1342}
1343
1344bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1345 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1346 aligned_expand_bytes = align_up(aligned_expand_bytes,
1347 HeapRegion::GrainBytes);
1348
1349 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1350 expand_bytes, aligned_expand_bytes);
1351
1352 if (is_maximal_no_gc()) {
1353 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1354 return false;
1355 }
1356
1357 double expand_heap_start_time_sec = os::elapsedTime();
1358 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1359 assert(regions_to_expand > 0, "Must expand by at least one region");
1360
1361 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1362 if (expand_time_ms != NULL) {
1363 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1364 }
1365
1366 if (expanded_by > 0) {
1367 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1368 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1369 policy()->record_new_heap_size(num_regions());
1370 } else {
1371 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1372
1373 // The expansion of the virtual storage space was unsuccessful.
1374 // Let's see if it was because we ran out of swap.
1375 if (G1ExitOnExpansionFailure &&
1376 _hrm->available() >= regions_to_expand) {
1377 // We had head room...
1378 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1379 }
1380 }
1381 return regions_to_expand > 0;
1382}
1383
1384void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1385 size_t aligned_shrink_bytes =
1386 ReservedSpace::page_align_size_down(shrink_bytes);
1387 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1388 HeapRegion::GrainBytes);
1389 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1390
1391 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1392 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1393
1394
1395 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1396 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1397 if (num_regions_removed > 0) {
1398 policy()->record_new_heap_size(num_regions());
1399 } else {
1400 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1401 }
1402}
1403
1404void G1CollectedHeap::shrink(size_t shrink_bytes) {
1405 _verifier->verify_region_sets_optional();
1406
1407 // We should only reach here at the end of a Full GC or during Remark which
1408 // means we should not not be holding to any GC alloc regions. The method
1409 // below will make sure of that and do any remaining clean up.
1410 _allocator->abandon_gc_alloc_regions();
1411
1412 // Instead of tearing down / rebuilding the free lists here, we
1413 // could instead use the remove_all_pending() method on free_list to
1414 // remove only the ones that we need to remove.
1415 tear_down_region_sets(true /* free_list_only */);
1416 shrink_helper(shrink_bytes);
1417 rebuild_region_sets(true /* free_list_only */);
1418
1419 _hrm->verify_optional();
1420 _verifier->verify_region_sets_optional();
1421}
1422
1423class OldRegionSetChecker : public HeapRegionSetChecker {
1424public:
1425 void check_mt_safety() {
1426 // Master Old Set MT safety protocol:
1427 // (a) If we're at a safepoint, operations on the master old set
1428 // should be invoked:
1429 // - by the VM thread (which will serialize them), or
1430 // - by the GC workers while holding the FreeList_lock, if we're
1431 // at a safepoint for an evacuation pause (this lock is taken
1432 // anyway when an GC alloc region is retired so that a new one
1433 // is allocated from the free list), or
1434 // - by the GC workers while holding the OldSets_lock, if we're at a
1435 // safepoint for a cleanup pause.
1436 // (b) If we're not at a safepoint, operations on the master old set
1437 // should be invoked while holding the Heap_lock.
1438
1439 if (SafepointSynchronize::is_at_safepoint()) {
1440 guarantee(Thread::current()->is_VM_thread() ||
1441 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1442 "master old set MT safety protocol at a safepoint");
1443 } else {
1444 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1445 }
1446 }
1447 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1448 const char* get_description() { return "Old Regions"; }
1449};
1450
1451class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1452public:
1453 void check_mt_safety() {
1454 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1455 "May only change archive regions during initialization or safepoint.");
1456 }
1457 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1458 const char* get_description() { return "Archive Regions"; }
1459};
1460
1461class HumongousRegionSetChecker : public HeapRegionSetChecker {
1462public:
1463 void check_mt_safety() {
1464 // Humongous Set MT safety protocol:
1465 // (a) If we're at a safepoint, operations on the master humongous
1466 // set should be invoked by either the VM thread (which will
1467 // serialize them) or by the GC workers while holding the
1468 // OldSets_lock.
1469 // (b) If we're not at a safepoint, operations on the master
1470 // humongous set should be invoked while holding the Heap_lock.
1471
1472 if (SafepointSynchronize::is_at_safepoint()) {
1473 guarantee(Thread::current()->is_VM_thread() ||
1474 OldSets_lock->owned_by_self(),
1475 "master humongous set MT safety protocol at a safepoint");
1476 } else {
1477 guarantee(Heap_lock->owned_by_self(),
1478 "master humongous set MT safety protocol outside a safepoint");
1479 }
1480 }
1481 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1482 const char* get_description() { return "Humongous Regions"; }
1483};
1484
1485G1CollectedHeap::G1CollectedHeap() :
1486 CollectedHeap(),
1487 _young_gen_sampling_thread(NULL),
1488 _workers(NULL),
1489 _card_table(NULL),
1490 _soft_ref_policy(),
1491 _old_set("Old Region Set", new OldRegionSetChecker()),
1492 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1493 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1494 _bot(NULL),
1495 _listener(),
1496 _hrm(NULL),
1497 _allocator(NULL),
1498 _verifier(NULL),
1499 _summary_bytes_used(0),
1500 _archive_allocator(NULL),
1501 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1502 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1503 _expand_heap_after_alloc_failure(true),
1504 _g1mm(NULL),
1505 _humongous_reclaim_candidates(),
1506 _has_humongous_reclaim_candidates(false),
1507 _hr_printer(),
1508 _collector_state(),
1509 _old_marking_cycles_started(0),
1510 _old_marking_cycles_completed(0),
1511 _eden(),
1512 _survivor(),
1513 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1514 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1515 _policy(G1Policy::create_policy(_gc_timer_stw)),
1516 _heap_sizing_policy(NULL),
1517 _collection_set(this, _policy),
1518 _hot_card_cache(NULL),
1519 _rem_set(NULL),
1520 _dirty_card_queue_set(false),
1521 _cm(NULL),
1522 _cm_thread(NULL),
1523 _cr(NULL),
1524 _task_queues(NULL),
1525 _evacuation_failed(false),
1526 _evacuation_failed_info_array(NULL),
1527 _preserved_marks_set(true /* in_c_heap */),
1528#ifndef PRODUCT
1529 _evacuation_failure_alot_for_current_gc(false),
1530 _evacuation_failure_alot_gc_number(0),
1531 _evacuation_failure_alot_count(0),
1532#endif
1533 _ref_processor_stw(NULL),
1534 _is_alive_closure_stw(this),
1535 _is_subject_to_discovery_stw(this),
1536 _ref_processor_cm(NULL),
1537 _is_alive_closure_cm(this),
1538 _is_subject_to_discovery_cm(this),
1539 _region_attr() {
1540
1541 _verifier = new G1HeapVerifier(this);
1542
1543 _allocator = new G1Allocator(this);
1544
1545 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1546
1547 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1548
1549 // Override the default _filler_array_max_size so that no humongous filler
1550 // objects are created.
1551 _filler_array_max_size = _humongous_object_threshold_in_words;
1552
1553 uint n_queues = ParallelGCThreads;
1554 _task_queues = new RefToScanQueueSet(n_queues);
1555
1556 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1557
1558 for (uint i = 0; i < n_queues; i++) {
1559 RefToScanQueue* q = new RefToScanQueue();
1560 q->initialize();
1561 _task_queues->register_queue(i, q);
1562 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1563 }
1564
1565 // Initialize the G1EvacuationFailureALot counters and flags.
1566 NOT_PRODUCT(reset_evacuation_should_fail();)
1567
1568 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1569}
1570
1571static size_t actual_reserved_page_size(ReservedSpace rs) {
1572 size_t page_size = os::vm_page_size();
1573 if (UseLargePages) {
1574 // There are two ways to manage large page memory.
1575 // 1. OS supports committing large page memory.
1576 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1577 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1578 // we reserved memory without large page.
1579 if (os::can_commit_large_page_memory() || rs.special()) {
1580 // An alignment at ReservedSpace comes from preferred page size or
1581 // heap alignment, and if the alignment came from heap alignment, it could be
1582 // larger than large pages size. So need to cap with the large page size.
1583 page_size = MIN2(rs.alignment(), os::large_page_size());
1584 }
1585 }
1586
1587 return page_size;
1588}
1589
1590G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1591 size_t size,
1592 size_t translation_factor) {
1593 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1594 // Allocate a new reserved space, preferring to use large pages.
1595 ReservedSpace rs(size, preferred_page_size);
1596 size_t page_size = actual_reserved_page_size(rs);
1597 G1RegionToSpaceMapper* result =
1598 G1RegionToSpaceMapper::create_mapper(rs,
1599 size,
1600 page_size,
1601 HeapRegion::GrainBytes,
1602 translation_factor,
1603 mtGC);
1604
1605 os::trace_page_sizes_for_requested_size(description,
1606 size,
1607 preferred_page_size,
1608 page_size,
1609 rs.base(),
1610 rs.size());
1611
1612 return result;
1613}
1614
1615jint G1CollectedHeap::initialize_concurrent_refinement() {
1616 jint ecode = JNI_OK;
1617 _cr = G1ConcurrentRefine::create(&ecode);
1618 return ecode;
1619}
1620
1621jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1622 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1623 if (_young_gen_sampling_thread->osthread() == NULL) {
1624 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1625 return JNI_ENOMEM;
1626 }
1627 return JNI_OK;
1628}
1629
1630jint G1CollectedHeap::initialize() {
1631 os::enable_vtime();
1632
1633 // Necessary to satisfy locking discipline assertions.
1634
1635 MutexLocker x(Heap_lock);
1636
1637 // While there are no constraints in the GC code that HeapWordSize
1638 // be any particular value, there are multiple other areas in the
1639 // system which believe this to be true (e.g. oop->object_size in some
1640 // cases incorrectly returns the size in wordSize units rather than
1641 // HeapWordSize).
1642 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1643
1644 size_t init_byte_size = InitialHeapSize;
1645 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1646
1647 // Ensure that the sizes are properly aligned.
1648 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1649 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1650 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1651
1652 // Reserve the maximum.
1653
1654 // When compressed oops are enabled, the preferred heap base
1655 // is calculated by subtracting the requested size from the
1656 // 32Gb boundary and using the result as the base address for
1657 // heap reservation. If the requested size is not aligned to
1658 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1659 // into the ReservedHeapSpace constructor) then the actual
1660 // base of the reserved heap may end up differing from the
1661 // address that was requested (i.e. the preferred heap base).
1662 // If this happens then we could end up using a non-optimal
1663 // compressed oops mode.
1664
1665 ReservedSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1666 HeapAlignment);
1667
1668 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1669
1670 // Create the barrier set for the entire reserved region.
1671 G1CardTable* ct = new G1CardTable(reserved_region());
1672 ct->initialize();
1673 G1BarrierSet* bs = new G1BarrierSet(ct);
1674 bs->initialize();
1675 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1676 BarrierSet::set_barrier_set(bs);
1677 _card_table = ct;
1678
1679 G1BarrierSet::satb_mark_queue_set().initialize(this,
1680 SATB_Q_CBL_mon,
1681 &bs->satb_mark_queue_buffer_allocator(),
1682 G1SATBProcessCompletedThreshold,
1683 G1SATBBufferEnqueueingThresholdPercent);
1684
1685 // process_completed_buffers_threshold and max_completed_buffers are updated
1686 // later, based on the concurrent refinement object.
1687 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1688 &bs->dirty_card_queue_buffer_allocator(),
1689 true); // init_free_ids
1690
1691 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1692 &bs->dirty_card_queue_buffer_allocator());
1693
1694 // Create the hot card cache.
1695 _hot_card_cache = new G1HotCardCache(this);
1696
1697 // Carve out the G1 part of the heap.
1698 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1699 size_t page_size = actual_reserved_page_size(heap_rs);
1700 G1RegionToSpaceMapper* heap_storage =
1701 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1702 g1_rs.size(),
1703 page_size,
1704 HeapRegion::GrainBytes,
1705 1,
1706 mtJavaHeap);
1707 if(heap_storage == NULL) {
1708 vm_shutdown_during_initialization("Could not initialize G1 heap");
1709 return JNI_ERR;
1710 }
1711
1712 os::trace_page_sizes("Heap",
1713 MinHeapSize,
1714 reserved_byte_size,
1715 page_size,
1716 heap_rs.base(),
1717 heap_rs.size());
1718 heap_storage->set_mapping_changed_listener(&_listener);
1719
1720 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1721 G1RegionToSpaceMapper* bot_storage =
1722 create_aux_memory_mapper("Block Offset Table",
1723 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1724 G1BlockOffsetTable::heap_map_factor());
1725
1726 G1RegionToSpaceMapper* cardtable_storage =
1727 create_aux_memory_mapper("Card Table",
1728 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1729 G1CardTable::heap_map_factor());
1730
1731 G1RegionToSpaceMapper* card_counts_storage =
1732 create_aux_memory_mapper("Card Counts Table",
1733 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1734 G1CardCounts::heap_map_factor());
1735
1736 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1737 G1RegionToSpaceMapper* prev_bitmap_storage =
1738 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1739 G1RegionToSpaceMapper* next_bitmap_storage =
1740 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1741
1742 _hrm = HeapRegionManager::create_manager(this);
1743
1744 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1745 _card_table->initialize(cardtable_storage);
1746 // Do later initialization work for concurrent refinement.
1747 _hot_card_cache->initialize(card_counts_storage);
1748
1749 // 6843694 - ensure that the maximum region index can fit
1750 // in the remembered set structures.
1751 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1752 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1753
1754 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1755 // start within the first card.
1756 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1757 // Also create a G1 rem set.
1758 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1759 _rem_set->initialize(max_reserved_capacity(), max_regions());
1760
1761 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1762 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1763 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1764 "too many cards per region");
1765
1766 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1767
1768 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1769
1770 {
1771 HeapWord* start = _hrm->reserved().start();
1772 HeapWord* end = _hrm->reserved().end();
1773 size_t granularity = HeapRegion::GrainBytes;
1774
1775 _region_attr.initialize(start, end, granularity);
1776 _humongous_reclaim_candidates.initialize(start, end, granularity);
1777 }
1778
1779 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1780 true /* are_GC_task_threads */,
1781 false /* are_ConcurrentGC_threads */);
1782 if (_workers == NULL) {
1783 return JNI_ENOMEM;
1784 }
1785 _workers->initialize_workers();
1786
1787 // Create the G1ConcurrentMark data structure and thread.
1788 // (Must do this late, so that "max_regions" is defined.)
1789 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1790 if (_cm == NULL || !_cm->completed_initialization()) {
1791 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1792 return JNI_ENOMEM;
1793 }
1794 _cm_thread = _cm->cm_thread();
1795
1796 // Now expand into the initial heap size.
1797 if (!expand(init_byte_size, _workers)) {
1798 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1799 return JNI_ENOMEM;
1800 }
1801
1802 // Perform any initialization actions delegated to the policy.
1803 policy()->init(this, &_collection_set);
1804
1805 jint ecode = initialize_concurrent_refinement();
1806 if (ecode != JNI_OK) {
1807 return ecode;
1808 }
1809
1810 ecode = initialize_young_gen_sampling_thread();
1811 if (ecode != JNI_OK) {
1812 return ecode;
1813 }
1814
1815 {
1816 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1817 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1818 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1819 }
1820
1821 // Here we allocate the dummy HeapRegion that is required by the
1822 // G1AllocRegion class.
1823 HeapRegion* dummy_region = _hrm->get_dummy_region();
1824
1825 // We'll re-use the same region whether the alloc region will
1826 // require BOT updates or not and, if it doesn't, then a non-young
1827 // region will complain that it cannot support allocations without
1828 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1829 dummy_region->set_eden();
1830 // Make sure it's full.
1831 dummy_region->set_top(dummy_region->end());
1832 G1AllocRegion::setup(this, dummy_region);
1833
1834 _allocator->init_mutator_alloc_region();
1835
1836 // Do create of the monitoring and management support so that
1837 // values in the heap have been properly initialized.
1838 _g1mm = new G1MonitoringSupport(this);
1839
1840 G1StringDedup::initialize();
1841
1842 _preserved_marks_set.init(ParallelGCThreads);
1843
1844 _collection_set.initialize(max_regions());
1845
1846 return JNI_OK;
1847}
1848
1849void G1CollectedHeap::stop() {
1850 // Stop all concurrent threads. We do this to make sure these threads
1851 // do not continue to execute and access resources (e.g. logging)
1852 // that are destroyed during shutdown.
1853 _cr->stop();
1854 _young_gen_sampling_thread->stop();
1855 _cm_thread->stop();
1856 if (G1StringDedup::is_enabled()) {
1857 G1StringDedup::stop();
1858 }
1859}
1860
1861void G1CollectedHeap::safepoint_synchronize_begin() {
1862 SuspendibleThreadSet::synchronize();
1863}
1864
1865void G1CollectedHeap::safepoint_synchronize_end() {
1866 SuspendibleThreadSet::desynchronize();
1867}
1868
1869void G1CollectedHeap::post_initialize() {
1870 CollectedHeap::post_initialize();
1871 ref_processing_init();
1872}
1873
1874void G1CollectedHeap::ref_processing_init() {
1875 // Reference processing in G1 currently works as follows:
1876 //
1877 // * There are two reference processor instances. One is
1878 // used to record and process discovered references
1879 // during concurrent marking; the other is used to
1880 // record and process references during STW pauses
1881 // (both full and incremental).
1882 // * Both ref processors need to 'span' the entire heap as
1883 // the regions in the collection set may be dotted around.
1884 //
1885 // * For the concurrent marking ref processor:
1886 // * Reference discovery is enabled at initial marking.
1887 // * Reference discovery is disabled and the discovered
1888 // references processed etc during remarking.
1889 // * Reference discovery is MT (see below).
1890 // * Reference discovery requires a barrier (see below).
1891 // * Reference processing may or may not be MT
1892 // (depending on the value of ParallelRefProcEnabled
1893 // and ParallelGCThreads).
1894 // * A full GC disables reference discovery by the CM
1895 // ref processor and abandons any entries on it's
1896 // discovered lists.
1897 //
1898 // * For the STW processor:
1899 // * Non MT discovery is enabled at the start of a full GC.
1900 // * Processing and enqueueing during a full GC is non-MT.
1901 // * During a full GC, references are processed after marking.
1902 //
1903 // * Discovery (may or may not be MT) is enabled at the start
1904 // of an incremental evacuation pause.
1905 // * References are processed near the end of a STW evacuation pause.
1906 // * For both types of GC:
1907 // * Discovery is atomic - i.e. not concurrent.
1908 // * Reference discovery will not need a barrier.
1909
1910 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1911
1912 // Concurrent Mark ref processor
1913 _ref_processor_cm =
1914 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1915 mt_processing, // mt processing
1916 ParallelGCThreads, // degree of mt processing
1917 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1918 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1919 false, // Reference discovery is not atomic
1920 &_is_alive_closure_cm, // is alive closure
1921 true); // allow changes to number of processing threads
1922
1923 // STW ref processor
1924 _ref_processor_stw =
1925 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1926 mt_processing, // mt processing
1927 ParallelGCThreads, // degree of mt processing
1928 (ParallelGCThreads > 1), // mt discovery
1929 ParallelGCThreads, // degree of mt discovery
1930 true, // Reference discovery is atomic
1931 &_is_alive_closure_stw, // is alive closure
1932 true); // allow changes to number of processing threads
1933}
1934
1935SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1936 return &_soft_ref_policy;
1937}
1938
1939size_t G1CollectedHeap::capacity() const {
1940 return _hrm->length() * HeapRegion::GrainBytes;
1941}
1942
1943size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1944 return _hrm->total_free_bytes();
1945}
1946
1947void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1948 _hot_card_cache->drain(cl, worker_i);
1949}
1950
1951void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1952 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1953 size_t n_completed_buffers = 0;
1954 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1955 n_completed_buffers++;
1956 }
1957 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!");
1958 phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1959}
1960
1961// Computes the sum of the storage used by the various regions.
1962size_t G1CollectedHeap::used() const {
1963 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1964 if (_archive_allocator != NULL) {
1965 result += _archive_allocator->used();
1966 }
1967 return result;
1968}
1969
1970size_t G1CollectedHeap::used_unlocked() const {
1971 return _summary_bytes_used;
1972}
1973
1974class SumUsedClosure: public HeapRegionClosure {
1975 size_t _used;
1976public:
1977 SumUsedClosure() : _used(0) {}
1978 bool do_heap_region(HeapRegion* r) {
1979 _used += r->used();
1980 return false;
1981 }
1982 size_t result() { return _used; }
1983};
1984
1985size_t G1CollectedHeap::recalculate_used() const {
1986 SumUsedClosure blk;
1987 heap_region_iterate(&blk);
1988 return blk.result();
1989}
1990
1991bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1992 switch (cause) {
1993 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1994 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1995 case GCCause::_wb_conc_mark: return true;
1996 default : return false;
1997 }
1998}
1999
2000bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2001 switch (cause) {
2002 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2003 case GCCause::_g1_humongous_allocation: return true;
2004 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2005 default: return is_user_requested_concurrent_full_gc(cause);
2006 }
2007}
2008
2009bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2010 if(policy()->force_upgrade_to_full()) {
2011 return true;
2012 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2013 return false;
2014 } else if (has_regions_left_for_allocation()) {
2015 return false;
2016 } else {
2017 return true;
2018 }
2019}
2020
2021#ifndef PRODUCT
2022void G1CollectedHeap::allocate_dummy_regions() {
2023 // Let's fill up most of the region
2024 size_t word_size = HeapRegion::GrainWords - 1024;
2025 // And as a result the region we'll allocate will be humongous.
2026 guarantee(is_humongous(word_size), "sanity");
2027
2028 // _filler_array_max_size is set to humongous object threshold
2029 // but temporarily change it to use CollectedHeap::fill_with_object().
2030 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2031
2032 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2033 // Let's use the existing mechanism for the allocation
2034 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2035 if (dummy_obj != NULL) {
2036 MemRegion mr(dummy_obj, word_size);
2037 CollectedHeap::fill_with_object(mr);
2038 } else {
2039 // If we can't allocate once, we probably cannot allocate
2040 // again. Let's get out of the loop.
2041 break;
2042 }
2043 }
2044}
2045#endif // !PRODUCT
2046
2047void G1CollectedHeap::increment_old_marking_cycles_started() {
2048 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2049 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2050 "Wrong marking cycle count (started: %d, completed: %d)",
2051 _old_marking_cycles_started, _old_marking_cycles_completed);
2052
2053 _old_marking_cycles_started++;
2054}
2055
2056void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2057 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2058
2059 // We assume that if concurrent == true, then the caller is a
2060 // concurrent thread that was joined the Suspendible Thread
2061 // Set. If there's ever a cheap way to check this, we should add an
2062 // assert here.
2063
2064 // Given that this method is called at the end of a Full GC or of a
2065 // concurrent cycle, and those can be nested (i.e., a Full GC can
2066 // interrupt a concurrent cycle), the number of full collections
2067 // completed should be either one (in the case where there was no
2068 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2069 // behind the number of full collections started.
2070
2071 // This is the case for the inner caller, i.e. a Full GC.
2072 assert(concurrent ||
2073 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2074 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2075 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2076 "is inconsistent with _old_marking_cycles_completed = %u",
2077 _old_marking_cycles_started, _old_marking_cycles_completed);
2078
2079 // This is the case for the outer caller, i.e. the concurrent cycle.
2080 assert(!concurrent ||
2081 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2082 "for outer caller (concurrent cycle): "
2083 "_old_marking_cycles_started = %u "
2084 "is inconsistent with _old_marking_cycles_completed = %u",
2085 _old_marking_cycles_started, _old_marking_cycles_completed);
2086
2087 _old_marking_cycles_completed += 1;
2088
2089 // We need to clear the "in_progress" flag in the CM thread before
2090 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2091 // is set) so that if a waiter requests another System.gc() it doesn't
2092 // incorrectly see that a marking cycle is still in progress.
2093 if (concurrent) {
2094 _cm_thread->set_idle();
2095 }
2096
2097 // This notify_all() will ensure that a thread that called
2098 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2099 // and it's waiting for a full GC to finish will be woken up. It is
2100 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2101 FullGCCount_lock->notify_all();
2102}
2103
2104void G1CollectedHeap::collect(GCCause::Cause cause) {
2105 try_collect(cause, true);
2106}
2107
2108bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2109 assert_heap_not_locked();
2110
2111 bool gc_succeeded;
2112 bool should_retry_gc;
2113
2114 do {
2115 should_retry_gc = false;
2116
2117 uint gc_count_before;
2118 uint old_marking_count_before;
2119 uint full_gc_count_before;
2120
2121 {
2122 MutexLocker ml(Heap_lock);
2123
2124 // Read the GC count while holding the Heap_lock
2125 gc_count_before = total_collections();
2126 full_gc_count_before = total_full_collections();
2127 old_marking_count_before = _old_marking_cycles_started;
2128 }
2129
2130 if (should_do_concurrent_full_gc(cause)) {
2131 // Schedule an initial-mark evacuation pause that will start a
2132 // concurrent cycle. We're setting word_size to 0 which means that
2133 // we are not requesting a post-GC allocation.
2134 VM_G1CollectForAllocation op(0, /* word_size */
2135 gc_count_before,
2136 cause,
2137 true, /* should_initiate_conc_mark */
2138 policy()->max_pause_time_ms());
2139 VMThread::execute(&op);
2140 gc_succeeded = op.gc_succeeded();
2141 if (!gc_succeeded && retry_on_gc_failure) {
2142 if (old_marking_count_before == _old_marking_cycles_started) {
2143 should_retry_gc = op.should_retry_gc();
2144 } else {
2145 // A Full GC happened while we were trying to schedule the
2146 // concurrent cycle. No point in starting a new cycle given
2147 // that the whole heap was collected anyway.
2148 }
2149
2150 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2151 GCLocker::stall_until_clear();
2152 }
2153 }
2154 } else {
2155 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2156 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2157
2158 // Schedule a standard evacuation pause. We're setting word_size
2159 // to 0 which means that we are not requesting a post-GC allocation.
2160 VM_G1CollectForAllocation op(0, /* word_size */
2161 gc_count_before,
2162 cause,
2163 false, /* should_initiate_conc_mark */
2164 policy()->max_pause_time_ms());
2165 VMThread::execute(&op);
2166 gc_succeeded = op.gc_succeeded();
2167 } else {
2168 // Schedule a Full GC.
2169 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2170 VMThread::execute(&op);
2171 gc_succeeded = op.gc_succeeded();
2172 }
2173 }
2174 } while (should_retry_gc);
2175 return gc_succeeded;
2176}
2177
2178bool G1CollectedHeap::is_in(const void* p) const {
2179 if (_hrm->reserved().contains(p)) {
2180 // Given that we know that p is in the reserved space,
2181 // heap_region_containing() should successfully
2182 // return the containing region.
2183 HeapRegion* hr = heap_region_containing(p);
2184 return hr->is_in(p);
2185 } else {
2186 return false;
2187 }
2188}
2189
2190#ifdef ASSERT
2191bool G1CollectedHeap::is_in_exact(const void* p) const {
2192 bool contains = reserved_region().contains(p);
2193 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2194 if (contains && available) {
2195 return true;
2196 } else {
2197 return false;
2198 }
2199}
2200#endif
2201
2202// Iteration functions.
2203
2204// Iterates an ObjectClosure over all objects within a HeapRegion.
2205
2206class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2207 ObjectClosure* _cl;
2208public:
2209 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2210 bool do_heap_region(HeapRegion* r) {
2211 if (!r->is_continues_humongous()) {
2212 r->object_iterate(_cl);
2213 }
2214 return false;
2215 }
2216};
2217
2218void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2219 IterateObjectClosureRegionClosure blk(cl);
2220 heap_region_iterate(&blk);
2221}
2222
2223void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2224 _hrm->iterate(cl);
2225}
2226
2227void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2228 HeapRegionClaimer *hrclaimer,
2229 uint worker_id) const {
2230 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2231}
2232
2233void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2234 HeapRegionClaimer *hrclaimer) const {
2235 _hrm->par_iterate(cl, hrclaimer, 0);
2236}
2237
2238void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2239 _collection_set.iterate(cl);
2240}
2241
2242void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, uint worker_id) {
2243 _collection_set.iterate_incremental_part_from(cl, worker_id, workers()->active_workers());
2244}
2245
2246HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2247 HeapRegion* hr = heap_region_containing(addr);
2248 return hr->block_start(addr);
2249}
2250
2251bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2252 HeapRegion* hr = heap_region_containing(addr);
2253 return hr->block_is_obj(addr);
2254}
2255
2256bool G1CollectedHeap::supports_tlab_allocation() const {
2257 return true;
2258}
2259
2260size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2261 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2262}
2263
2264size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2265 return _eden.length() * HeapRegion::GrainBytes;
2266}
2267
2268// For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2269// must be equal to the humongous object limit.
2270size_t G1CollectedHeap::max_tlab_size() const {
2271 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2272}
2273
2274size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2275 return _allocator->unsafe_max_tlab_alloc();
2276}
2277
2278size_t G1CollectedHeap::max_capacity() const {
2279 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2280}
2281
2282size_t G1CollectedHeap::max_reserved_capacity() const {
2283 return _hrm->max_length() * HeapRegion::GrainBytes;
2284}
2285
2286jlong G1CollectedHeap::millis_since_last_gc() {
2287 // See the notes in GenCollectedHeap::millis_since_last_gc()
2288 // for more information about the implementation.
2289 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2290 _policy->collection_pause_end_millis();
2291 if (ret_val < 0) {
2292 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2293 ". returning zero instead.", ret_val);
2294 return 0;
2295 }
2296 return ret_val;
2297}
2298
2299void G1CollectedHeap::deduplicate_string(oop str) {
2300 assert(java_lang_String::is_instance(str), "invariant");
2301
2302 if (G1StringDedup::is_enabled()) {
2303 G1StringDedup::deduplicate(str);
2304 }
2305}
2306
2307void G1CollectedHeap::prepare_for_verify() {
2308 _verifier->prepare_for_verify();
2309}
2310
2311void G1CollectedHeap::verify(VerifyOption vo) {
2312 _verifier->verify(vo);
2313}
2314
2315bool G1CollectedHeap::supports_concurrent_phase_control() const {
2316 return true;
2317}
2318
2319bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2320 return _cm_thread->request_concurrent_phase(phase);
2321}
2322
2323bool G1CollectedHeap::is_heterogeneous_heap() const {
2324 return G1Arguments::is_heterogeneous_heap();
2325}
2326
2327class PrintRegionClosure: public HeapRegionClosure {
2328 outputStream* _st;
2329public:
2330 PrintRegionClosure(outputStream* st) : _st(st) {}
2331 bool do_heap_region(HeapRegion* r) {
2332 r->print_on(_st);
2333 return false;
2334 }
2335};
2336
2337bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2338 const HeapRegion* hr,
2339 const VerifyOption vo) const {
2340 switch (vo) {
2341 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2342 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2343 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2344 default: ShouldNotReachHere();
2345 }
2346 return false; // keep some compilers happy
2347}
2348
2349bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2350 const VerifyOption vo) const {
2351 switch (vo) {
2352 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2353 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2354 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2355 default: ShouldNotReachHere();
2356 }
2357 return false; // keep some compilers happy
2358}
2359
2360void G1CollectedHeap::print_heap_regions() const {
2361 LogTarget(Trace, gc, heap, region) lt;
2362 if (lt.is_enabled()) {
2363 LogStream ls(lt);
2364 print_regions_on(&ls);
2365 }
2366}
2367
2368void G1CollectedHeap::print_on(outputStream* st) const {
2369 st->print(" %-20s", "garbage-first heap");
2370 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2371 capacity()/K, used_unlocked()/K);
2372 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2373 p2i(_hrm->reserved().start()),
2374 p2i(_hrm->reserved().end()));
2375 st->cr();
2376 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2377 uint young_regions = young_regions_count();
2378 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2379 (size_t) young_regions * HeapRegion::GrainBytes / K);
2380 uint survivor_regions = survivor_regions_count();
2381 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2382 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2383 st->cr();
2384 MetaspaceUtils::print_on(st);
2385}
2386
2387void G1CollectedHeap::print_regions_on(outputStream* st) const {
2388 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2389 "HS=humongous(starts), HC=humongous(continues), "
2390 "CS=collection set, F=free, A=archive, "
2391 "TAMS=top-at-mark-start (previous, next)");
2392 PrintRegionClosure blk(st);
2393 heap_region_iterate(&blk);
2394}
2395
2396void G1CollectedHeap::print_extended_on(outputStream* st) const {
2397 print_on(st);
2398
2399 // Print the per-region information.
2400 print_regions_on(st);
2401}
2402
2403void G1CollectedHeap::print_on_error(outputStream* st) const {
2404 this->CollectedHeap::print_on_error(st);
2405
2406 if (_cm != NULL) {
2407 st->cr();
2408 _cm->print_on_error(st);
2409 }
2410}
2411
2412void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2413 workers()->print_worker_threads_on(st);
2414 _cm_thread->print_on(st);
2415 st->cr();
2416 _cm->print_worker_threads_on(st);
2417 _cr->print_threads_on(st);
2418 _young_gen_sampling_thread->print_on(st);
2419 if (G1StringDedup::is_enabled()) {
2420 G1StringDedup::print_worker_threads_on(st);
2421 }
2422}
2423
2424void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2425 workers()->threads_do(tc);
2426 tc->do_thread(_cm_thread);
2427 _cm->threads_do(tc);
2428 _cr->threads_do(tc);
2429 tc->do_thread(_young_gen_sampling_thread);
2430 if (G1StringDedup::is_enabled()) {
2431 G1StringDedup::threads_do(tc);
2432 }
2433}
2434
2435void G1CollectedHeap::print_tracing_info() const {
2436 rem_set()->print_summary_info();
2437 concurrent_mark()->print_summary_info();
2438}
2439
2440#ifndef PRODUCT
2441// Helpful for debugging RSet issues.
2442
2443class PrintRSetsClosure : public HeapRegionClosure {
2444private:
2445 const char* _msg;
2446 size_t _occupied_sum;
2447
2448public:
2449 bool do_heap_region(HeapRegion* r) {
2450 HeapRegionRemSet* hrrs = r->rem_set();
2451 size_t occupied = hrrs->occupied();
2452 _occupied_sum += occupied;
2453
2454 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2455 if (occupied == 0) {
2456 tty->print_cr(" RSet is empty");
2457 } else {
2458 hrrs->print();
2459 }
2460 tty->print_cr("----------");
2461 return false;
2462 }
2463
2464 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2465 tty->cr();
2466 tty->print_cr("========================================");
2467 tty->print_cr("%s", msg);
2468 tty->cr();
2469 }
2470
2471 ~PrintRSetsClosure() {
2472 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2473 tty->print_cr("========================================");
2474 tty->cr();
2475 }
2476};
2477
2478void G1CollectedHeap::print_cset_rsets() {
2479 PrintRSetsClosure cl("Printing CSet RSets");
2480 collection_set_iterate_all(&cl);
2481}
2482
2483void G1CollectedHeap::print_all_rsets() {
2484 PrintRSetsClosure cl("Printing All RSets");;
2485 heap_region_iterate(&cl);
2486}
2487#endif // PRODUCT
2488
2489G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2490
2491 size_t eden_used_bytes = _eden.used_bytes();
2492 size_t survivor_used_bytes = _survivor.used_bytes();
2493 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2494
2495 size_t eden_capacity_bytes =
2496 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2497
2498 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2499 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2500 eden_capacity_bytes, survivor_used_bytes, num_regions());
2501}
2502
2503G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2504 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2505 stats->unused(), stats->used(), stats->region_end_waste(),
2506 stats->regions_filled(), stats->direct_allocated(),
2507 stats->failure_used(), stats->failure_waste());
2508}
2509
2510void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2511 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2512 gc_tracer->report_gc_heap_summary(when, heap_summary);
2513
2514 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2515 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2516}
2517
2518G1CollectedHeap* G1CollectedHeap::heap() {
2519 CollectedHeap* heap = Universe::heap();
2520 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2521 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2522 return (G1CollectedHeap*)heap;
2523}
2524
2525void G1CollectedHeap::gc_prologue(bool full) {
2526 // always_do_update_barrier = false;
2527 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2528
2529 // This summary needs to be printed before incrementing total collections.
2530 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2531
2532 // Update common counters.
2533 increment_total_collections(full /* full gc */);
2534 if (full || collector_state()->in_initial_mark_gc()) {
2535 increment_old_marking_cycles_started();
2536 }
2537
2538 // Fill TLAB's and such
2539 double start = os::elapsedTime();
2540 ensure_parsability(true);
2541 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2542}
2543
2544void G1CollectedHeap::gc_epilogue(bool full) {
2545 // Update common counters.
2546 if (full) {
2547 // Update the number of full collections that have been completed.
2548 increment_old_marking_cycles_completed(false /* concurrent */);
2549 }
2550
2551 // We are at the end of the GC. Total collections has already been increased.
2552 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2553
2554 // FIXME: what is this about?
2555 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2556 // is set.
2557#if COMPILER2_OR_JVMCI
2558 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2559#endif
2560 // always_do_update_barrier = true;
2561
2562 double start = os::elapsedTime();
2563 resize_all_tlabs();
2564 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2565
2566 MemoryService::track_memory_usage();
2567 // We have just completed a GC. Update the soft reference
2568 // policy with the new heap occupancy
2569 Universe::update_heap_info_at_gc();
2570}
2571
2572HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2573 uint gc_count_before,
2574 bool* succeeded,
2575 GCCause::Cause gc_cause) {
2576 assert_heap_not_locked_and_not_at_safepoint();
2577 VM_G1CollectForAllocation op(word_size,
2578 gc_count_before,
2579 gc_cause,
2580 false, /* should_initiate_conc_mark */
2581 policy()->max_pause_time_ms());
2582 VMThread::execute(&op);
2583
2584 HeapWord* result = op.result();
2585 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2586 assert(result == NULL || ret_succeeded,
2587 "the result should be NULL if the VM did not succeed");
2588 *succeeded = ret_succeeded;
2589
2590 assert_heap_not_locked();
2591 return result;
2592}
2593
2594void G1CollectedHeap::do_concurrent_mark() {
2595 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2596 if (!_cm_thread->in_progress()) {
2597 _cm_thread->set_started();
2598 CGC_lock->notify();
2599 }
2600}
2601
2602size_t G1CollectedHeap::pending_card_num() {
2603 struct CountCardsClosure : public ThreadClosure {
2604 size_t _cards;
2605 CountCardsClosure() : _cards(0) {}
2606 virtual void do_thread(Thread* t) {
2607 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2608 }
2609 } count_from_threads;
2610 Threads::threads_do(&count_from_threads);
2611
2612 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2613 size_t buffer_size = dcqs.buffer_size();
2614 size_t buffer_num = dcqs.completed_buffers_num();
2615
2616 return buffer_size * buffer_num + count_from_threads._cards;
2617}
2618
2619bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2620 // We don't nominate objects with many remembered set entries, on
2621 // the assumption that such objects are likely still live.
2622 HeapRegionRemSet* rem_set = r->rem_set();
2623
2624 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2625 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2626 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2627}
2628
2629class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2630 private:
2631 size_t _total_humongous;
2632 size_t _candidate_humongous;
2633
2634 G1DirtyCardQueue _dcq;
2635
2636 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2637 assert(region->is_starts_humongous(), "Must start a humongous object");
2638
2639 oop obj = oop(region->bottom());
2640
2641 // Dead objects cannot be eager reclaim candidates. Due to class
2642 // unloading it is unsafe to query their classes so we return early.
2643 if (g1h->is_obj_dead(obj, region)) {
2644 return false;
2645 }
2646
2647 // If we do not have a complete remembered set for the region, then we can
2648 // not be sure that we have all references to it.
2649 if (!region->rem_set()->is_complete()) {
2650 return false;
2651 }
2652 // Candidate selection must satisfy the following constraints
2653 // while concurrent marking is in progress:
2654 //
2655 // * In order to maintain SATB invariants, an object must not be
2656 // reclaimed if it was allocated before the start of marking and
2657 // has not had its references scanned. Such an object must have
2658 // its references (including type metadata) scanned to ensure no
2659 // live objects are missed by the marking process. Objects
2660 // allocated after the start of concurrent marking don't need to
2661 // be scanned.
2662 //
2663 // * An object must not be reclaimed if it is on the concurrent
2664 // mark stack. Objects allocated after the start of concurrent
2665 // marking are never pushed on the mark stack.
2666 //
2667 // Nominating only objects allocated after the start of concurrent
2668 // marking is sufficient to meet both constraints. This may miss
2669 // some objects that satisfy the constraints, but the marking data
2670 // structures don't support efficiently performing the needed
2671 // additional tests or scrubbing of the mark stack.
2672 //
2673 // However, we presently only nominate is_typeArray() objects.
2674 // A humongous object containing references induces remembered
2675 // set entries on other regions. In order to reclaim such an
2676 // object, those remembered sets would need to be cleaned up.
2677 //
2678 // We also treat is_typeArray() objects specially, allowing them
2679 // to be reclaimed even if allocated before the start of
2680 // concurrent mark. For this we rely on mark stack insertion to
2681 // exclude is_typeArray() objects, preventing reclaiming an object
2682 // that is in the mark stack. We also rely on the metadata for
2683 // such objects to be built-in and so ensured to be kept live.
2684 // Frequent allocation and drop of large binary blobs is an
2685 // important use case for eager reclaim, and this special handling
2686 // may reduce needed headroom.
2687
2688 return obj->is_typeArray() &&
2689 g1h->is_potential_eager_reclaim_candidate(region);
2690 }
2691
2692 public:
2693 RegisterRegionsWithRegionAttrTableClosure()
2694 : _total_humongous(0),
2695 _candidate_humongous(0),
2696 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2697 }
2698
2699 virtual bool do_heap_region(HeapRegion* r) {
2700 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2701
2702 if (!r->is_starts_humongous()) {
2703 g1h->register_region_with_region_attr(r);
2704 return false;
2705 }
2706
2707 bool is_candidate = humongous_region_is_candidate(g1h, r);
2708 uint rindex = r->hrm_index();
2709 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2710 if (is_candidate) {
2711 _candidate_humongous++;
2712 g1h->register_humongous_region_with_region_attr(rindex);
2713 // Is_candidate already filters out humongous object with large remembered sets.
2714 // If we have a humongous object with a few remembered sets, we simply flush these
2715 // remembered set entries into the DCQS. That will result in automatic
2716 // re-evaluation of their remembered set entries during the following evacuation
2717 // phase.
2718 if (!r->rem_set()->is_empty()) {
2719 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2720 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2721 G1CardTable* ct = g1h->card_table();
2722 HeapRegionRemSetIterator hrrs(r->rem_set());
2723 size_t card_index;
2724 while (hrrs.has_next(card_index)) {
2725 CardTable::CardValue* card_ptr = ct->byte_for_index(card_index);
2726 // The remembered set might contain references to already freed
2727 // regions. Filter out such entries to avoid failing card table
2728 // verification.
2729 if (g1h->is_in(ct->addr_for(card_ptr))) {
2730 if (*card_ptr != G1CardTable::dirty_card_val()) {
2731 *card_ptr = G1CardTable::dirty_card_val();
2732 _dcq.enqueue(card_ptr);
2733 }
2734 }
2735 }
2736 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2737 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2738 hrrs.n_yielded(), r->rem_set()->occupied());
2739 // We should only clear the card based remembered set here as we will not
2740 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2741 // (and probably never) we do not enter this path if there are other kind of
2742 // remembered sets for this region.
2743 r->rem_set()->clear_locked(true /* only_cardset */);
2744 // Clear_locked() above sets the state to Empty. However we want to continue
2745 // collecting remembered set entries for humongous regions that were not
2746 // reclaimed.
2747 r->rem_set()->set_state_complete();
2748#ifdef ASSERT
2749 G1HeapRegionAttr region_attr = g1h->region_attr(oop(r->bottom()));
2750 assert(region_attr.needs_remset_update(), "must be");
2751#endif
2752 }
2753 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2754 } else {
2755 g1h->register_region_with_region_attr(r);
2756 }
2757 _total_humongous++;
2758
2759 return false;
2760 }
2761
2762 size_t total_humongous() const { return _total_humongous; }
2763 size_t candidate_humongous() const { return _candidate_humongous; }
2764
2765 void flush_rem_set_entries() { _dcq.flush(); }
2766};
2767
2768void G1CollectedHeap::register_regions_with_region_attr() {
2769 Ticks start = Ticks::now();
2770
2771 RegisterRegionsWithRegionAttrTableClosure cl;
2772 heap_region_iterate(&cl);
2773
2774 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2775 cl.total_humongous(),
2776 cl.candidate_humongous());
2777 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2778
2779 // Finally flush all remembered set entries to re-check into the global DCQS.
2780 cl.flush_rem_set_entries();
2781}
2782
2783#ifndef PRODUCT
2784void G1CollectedHeap::verify_region_attr_remset_update() {
2785 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2786 public:
2787 virtual bool do_heap_region(HeapRegion* r) {
2788 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2789 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2790 assert(r->rem_set()->is_tracked() == needs_remset_update,
2791 "Region %u remset tracking status (%s) different to region attribute (%s)",
2792 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2793 return false;
2794 }
2795 } cl;
2796 heap_region_iterate(&cl);
2797}
2798#endif
2799
2800class VerifyRegionRemSetClosure : public HeapRegionClosure {
2801 public:
2802 bool do_heap_region(HeapRegion* hr) {
2803 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2804 hr->verify_rem_set();
2805 }
2806 return false;
2807 }
2808};
2809
2810uint G1CollectedHeap::num_task_queues() const {
2811 return _task_queues->size();
2812}
2813
2814#if TASKQUEUE_STATS
2815void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2816 st->print_raw_cr("GC Task Stats");
2817 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2818 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2819}
2820
2821void G1CollectedHeap::print_taskqueue_stats() const {
2822 if (!log_is_enabled(Trace, gc, task, stats)) {
2823 return;
2824 }
2825 Log(gc, task, stats) log;
2826 ResourceMark rm;
2827 LogStream ls(log.trace());
2828 outputStream* st = &ls;
2829
2830 print_taskqueue_stats_hdr(st);
2831
2832 TaskQueueStats totals;
2833 const uint n = num_task_queues();
2834 for (uint i = 0; i < n; ++i) {
2835 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2836 totals += task_queue(i)->stats;
2837 }
2838 st->print_raw("tot "); totals.print(st); st->cr();
2839
2840 DEBUG_ONLY(totals.verify());
2841}
2842
2843void G1CollectedHeap::reset_taskqueue_stats() {
2844 const uint n = num_task_queues();
2845 for (uint i = 0; i < n; ++i) {
2846 task_queue(i)->stats.reset();
2847 }
2848}
2849#endif // TASKQUEUE_STATS
2850
2851void G1CollectedHeap::wait_for_root_region_scanning() {
2852 double scan_wait_start = os::elapsedTime();
2853 // We have to wait until the CM threads finish scanning the
2854 // root regions as it's the only way to ensure that all the
2855 // objects on them have been correctly scanned before we start
2856 // moving them during the GC.
2857 bool waited = _cm->root_regions()->wait_until_scan_finished();
2858 double wait_time_ms = 0.0;
2859 if (waited) {
2860 double scan_wait_end = os::elapsedTime();
2861 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2862 }
2863 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2864}
2865
2866class G1PrintCollectionSetClosure : public HeapRegionClosure {
2867private:
2868 G1HRPrinter* _hr_printer;
2869public:
2870 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2871
2872 virtual bool do_heap_region(HeapRegion* r) {
2873 _hr_printer->cset(r);
2874 return false;
2875 }
2876};
2877
2878void G1CollectedHeap::start_new_collection_set() {
2879 double start = os::elapsedTime();
2880
2881 collection_set()->start_incremental_building();
2882
2883 clear_region_attr();
2884
2885 guarantee(_eden.length() == 0, "eden should have been cleared");
2886 policy()->transfer_survivors_to_cset(survivor());
2887
2888 // We redo the verification but now wrt to the new CSet which
2889 // has just got initialized after the previous CSet was freed.
2890 _cm->verify_no_collection_set_oops();
2891
2892 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2893}
2894
2895void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2896
2897 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2898 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2899 collection_set()->optional_region_length());
2900
2901 _cm->verify_no_collection_set_oops();
2902
2903 if (_hr_printer.is_active()) {
2904 G1PrintCollectionSetClosure cl(&_hr_printer);
2905 _collection_set.iterate(&cl);
2906 _collection_set.iterate_optional(&cl);
2907 }
2908}
2909
2910G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2911 if (collector_state()->in_initial_mark_gc()) {
2912 return G1HeapVerifier::G1VerifyConcurrentStart;
2913 } else if (collector_state()->in_young_only_phase()) {
2914 return G1HeapVerifier::G1VerifyYoungNormal;
2915 } else {
2916 return G1HeapVerifier::G1VerifyMixed;
2917 }
2918}
2919
2920void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2921 if (VerifyRememberedSets) {
2922 log_info(gc, verify)("[Verifying RemSets before GC]");
2923 VerifyRegionRemSetClosure v_cl;
2924 heap_region_iterate(&v_cl);
2925 }
2926 _verifier->verify_before_gc(type);
2927 _verifier->check_bitmaps("GC Start");
2928}
2929
2930void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2931 if (VerifyRememberedSets) {
2932 log_info(gc, verify)("[Verifying RemSets after GC]");
2933 VerifyRegionRemSetClosure v_cl;
2934 heap_region_iterate(&v_cl);
2935 }
2936 _verifier->verify_after_gc(type);
2937 _verifier->check_bitmaps("GC End");
2938}
2939
2940void G1CollectedHeap::expand_heap_after_young_collection(){
2941 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2942 if (expand_bytes > 0) {
2943 // No need for an ergo logging here,
2944 // expansion_amount() does this when it returns a value > 0.
2945 double expand_ms;
2946 if (!expand(expand_bytes, _workers, &expand_ms)) {
2947 // We failed to expand the heap. Cannot do anything about it.
2948 }
2949 phase_times()->record_expand_heap_time(expand_ms);
2950 }
2951}
2952
2953const char* G1CollectedHeap::young_gc_name() const {
2954 if (collector_state()->in_initial_mark_gc()) {
2955 return "Pause Young (Concurrent Start)";
2956 } else if (collector_state()->in_young_only_phase()) {
2957 if (collector_state()->in_young_gc_before_mixed()) {
2958 return "Pause Young (Prepare Mixed)";
2959 } else {
2960 return "Pause Young (Normal)";
2961 }
2962 } else {
2963 return "Pause Young (Mixed)";
2964 }
2965}
2966
2967bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2968 assert_at_safepoint_on_vm_thread();
2969 guarantee(!is_gc_active(), "collection is not reentrant");
2970
2971 if (GCLocker::check_active_before_gc()) {
2972 return false;
2973 }
2974
2975 GCIdMark gc_id_mark;
2976
2977 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2978 ResourceMark rm;
2979
2980 policy()->note_gc_start();
2981
2982 _gc_timer_stw->register_gc_start();
2983 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2984
2985 wait_for_root_region_scanning();
2986
2987 print_heap_before_gc();
2988 print_heap_regions();
2989 trace_heap_before_gc(_gc_tracer_stw);
2990
2991 _verifier->verify_region_sets_optional();
2992 _verifier->verify_dirty_young_regions();
2993
2994 // We should not be doing initial mark unless the conc mark thread is running
2995 if (!_cm_thread->should_terminate()) {
2996 // This call will decide whether this pause is an initial-mark
2997 // pause. If it is, in_initial_mark_gc() will return true
2998 // for the duration of this pause.
2999 policy()->decide_on_conc_mark_initiation();
3000 }
3001
3002 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3003 assert(!collector_state()->in_initial_mark_gc() ||
3004 collector_state()->in_young_only_phase(), "sanity");
3005 // We also do not allow mixed GCs during marking.
3006 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3007
3008 // Record whether this pause is an initial mark. When the current
3009 // thread has completed its logging output and it's safe to signal
3010 // the CM thread, the flag's value in the policy has been reset.
3011 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3012 if (should_start_conc_mark) {
3013 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3014 }
3015
3016 // Inner scope for scope based logging, timers, and stats collection
3017 {
3018 G1EvacuationInfo evacuation_info;
3019
3020 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3021
3022 GCTraceCPUTime tcpu;
3023
3024 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3025
3026 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3027 workers()->active_workers(),
3028 Threads::number_of_non_daemon_threads());
3029 active_workers = workers()->update_active_workers(active_workers);
3030 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3031
3032 G1MonitoringScope ms(g1mm(),
3033 false /* full_gc */,
3034 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3035
3036 G1HeapTransition heap_transition(this);
3037 size_t heap_used_bytes_before_gc = used();
3038
3039 {
3040 IsGCActiveMark x;
3041
3042 gc_prologue(false);
3043
3044 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3045 verify_before_young_collection(verify_type);
3046
3047 {
3048 // The elapsed time induced by the start time below deliberately elides
3049 // the possible verification above.
3050 double sample_start_time_sec = os::elapsedTime();
3051
3052 // Please see comment in g1CollectedHeap.hpp and
3053 // G1CollectedHeap::ref_processing_init() to see how
3054 // reference processing currently works in G1.
3055 _ref_processor_stw->enable_discovery();
3056
3057 // We want to temporarily turn off discovery by the
3058 // CM ref processor, if necessary, and turn it back on
3059 // on again later if we do. Using a scoped
3060 // NoRefDiscovery object will do this.
3061 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3062
3063 policy()->record_collection_pause_start(sample_start_time_sec);
3064
3065 // Forget the current allocation region (we might even choose it to be part
3066 // of the collection set!).
3067 _allocator->release_mutator_alloc_region();
3068
3069 calculate_collection_set(evacuation_info, target_pause_time_ms);
3070
3071 G1ParScanThreadStateSet per_thread_states(this,
3072 workers()->active_workers(),
3073 collection_set()->young_region_length(),
3074 collection_set()->optional_region_length());
3075 pre_evacuate_collection_set(evacuation_info);
3076
3077 // Actually do the work...
3078 evacuate_initial_collection_set(&per_thread_states);
3079
3080 if (_collection_set.optional_region_length() != 0) {
3081 evacuate_optional_collection_set(&per_thread_states);
3082 }
3083 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3084
3085 start_new_collection_set();
3086
3087 _survivor_evac_stats.adjust_desired_plab_sz();
3088 _old_evac_stats.adjust_desired_plab_sz();
3089
3090 if (should_start_conc_mark) {
3091 // We have to do this before we notify the CM threads that
3092 // they can start working to make sure that all the
3093 // appropriate initialization is done on the CM object.
3094 concurrent_mark()->post_initial_mark();
3095 // Note that we don't actually trigger the CM thread at
3096 // this point. We do that later when we're sure that
3097 // the current thread has completed its logging output.
3098 }
3099
3100 allocate_dummy_regions();
3101
3102 _allocator->init_mutator_alloc_region();
3103
3104 expand_heap_after_young_collection();
3105
3106 double sample_end_time_sec = os::elapsedTime();
3107 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3108 size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards) +
3109 phase_times()->sum_thread_work_items(G1GCPhaseTimes::OptScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3110 policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3111 }
3112
3113 verify_after_young_collection(verify_type);
3114
3115#ifdef TRACESPINNING
3116 ParallelTaskTerminator::print_termination_counts();
3117#endif
3118
3119 gc_epilogue(false);
3120 }
3121
3122 // Print the remainder of the GC log output.
3123 if (evacuation_failed()) {
3124 log_info(gc)("To-space exhausted");
3125 }
3126
3127 policy()->print_phases();
3128 heap_transition.print();
3129
3130 _hrm->verify_optional();
3131 _verifier->verify_region_sets_optional();
3132
3133 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3134 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3135
3136 print_heap_after_gc();
3137 print_heap_regions();
3138 trace_heap_after_gc(_gc_tracer_stw);
3139
3140 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3141 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3142 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3143 // before any GC notifications are raised.
3144 g1mm()->update_sizes();
3145
3146 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3147 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3148 _gc_timer_stw->register_gc_end();
3149 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3150 }
3151 // It should now be safe to tell the concurrent mark thread to start
3152 // without its logging output interfering with the logging output
3153 // that came from the pause.
3154
3155 if (should_start_conc_mark) {
3156 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3157 // thread(s) could be running concurrently with us. Make sure that anything
3158 // after this point does not assume that we are the only GC thread running.
3159 // Note: of course, the actual marking work will not start until the safepoint
3160 // itself is released in SuspendibleThreadSet::desynchronize().
3161 do_concurrent_mark();
3162 }
3163
3164 return true;
3165}
3166
3167void G1CollectedHeap::remove_self_forwarding_pointers() {
3168 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3169 workers()->run_task(&rsfp_task);
3170}
3171
3172void G1CollectedHeap::restore_after_evac_failure() {
3173 double remove_self_forwards_start = os::elapsedTime();
3174
3175 remove_self_forwarding_pointers();
3176 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3177 _preserved_marks_set.restore(&task_executor);
3178
3179 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3180}
3181
3182void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3183 if (!_evacuation_failed) {
3184 _evacuation_failed = true;
3185 }
3186
3187 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3188 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3189}
3190
3191bool G1ParEvacuateFollowersClosure::offer_termination() {
3192 EventGCPhaseParallel event;
3193 G1ParScanThreadState* const pss = par_scan_state();
3194 start_term_time();
3195 const bool res = terminator()->offer_termination();
3196 end_term_time();
3197 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3198 return res;
3199}
3200
3201void G1ParEvacuateFollowersClosure::do_void() {
3202 EventGCPhaseParallel event;
3203 G1ParScanThreadState* const pss = par_scan_state();
3204 pss->trim_queue();
3205 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3206 do {
3207 EventGCPhaseParallel event;
3208 pss->steal_and_trim_queue(queues());
3209 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3210 } while (!offer_termination());
3211}
3212
3213void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3214 bool class_unloading_occurred) {
3215 uint num_workers = workers()->active_workers();
3216 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3217 workers()->run_task(&unlink_task);
3218}
3219
3220// Clean string dedup data structures.
3221// Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3222// record the durations of the phases. Hence the almost-copy.
3223class G1StringDedupCleaningTask : public AbstractGangTask {
3224 BoolObjectClosure* _is_alive;
3225 OopClosure* _keep_alive;
3226 G1GCPhaseTimes* _phase_times;
3227
3228public:
3229 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3230 OopClosure* keep_alive,
3231 G1GCPhaseTimes* phase_times) :
3232 AbstractGangTask("Partial Cleaning Task"),
3233 _is_alive(is_alive),
3234 _keep_alive(keep_alive),
3235 _phase_times(phase_times)
3236 {
3237 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3238 StringDedup::gc_prologue(true);
3239 }
3240
3241 ~G1StringDedupCleaningTask() {
3242 StringDedup::gc_epilogue();
3243 }
3244
3245 void work(uint worker_id) {
3246 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3247 {
3248 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3249 StringDedupQueue::unlink_or_oops_do(&cl);
3250 }
3251 {
3252 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3253 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3254 }
3255 }
3256};
3257
3258void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3259 OopClosure* keep_alive,
3260 G1GCPhaseTimes* phase_times) {
3261 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3262 workers()->run_task(&cl);
3263}
3264
3265class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3266 private:
3267 G1DirtyCardQueueSet* _queue;
3268 G1CollectedHeap* _g1h;
3269 public:
3270 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3271 _queue(queue), _g1h(g1h) { }
3272
3273 virtual void work(uint worker_id) {
3274 G1GCPhaseTimes* p = _g1h->phase_times();
3275 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3276
3277 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3278 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3279
3280 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3281 }
3282};
3283
3284void G1CollectedHeap::redirty_logged_cards() {
3285 double redirty_logged_cards_start = os::elapsedTime();
3286
3287 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3288 dirty_card_queue_set().reset_for_par_iteration();
3289 workers()->run_task(&redirty_task);
3290
3291 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3292 dcq.merge_bufferlists(&dirty_card_queue_set());
3293 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3294
3295 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3296}
3297
3298// Weak Reference Processing support
3299
3300bool G1STWIsAliveClosure::do_object_b(oop p) {
3301 // An object is reachable if it is outside the collection set,
3302 // or is inside and copied.
3303 return !_g1h->is_in_cset(p) || p->is_forwarded();
3304}
3305
3306bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3307 assert(obj != NULL, "must not be NULL");
3308 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3309 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3310 // may falsely indicate that this is not the case here: however the collection set only
3311 // contains old regions when concurrent mark is not running.
3312 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3313}
3314
3315// Non Copying Keep Alive closure
3316class G1KeepAliveClosure: public OopClosure {
3317 G1CollectedHeap*_g1h;
3318public:
3319 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3320 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3321 void do_oop(oop* p) {
3322 oop obj = *p;
3323 assert(obj != NULL, "the caller should have filtered out NULL values");
3324
3325 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3326 if (!region_attr.is_in_cset_or_humongous()) {
3327 return;
3328 }
3329 if (region_attr.is_in_cset()) {
3330 assert( obj->is_forwarded(), "invariant" );
3331 *p = obj->forwardee();
3332 } else {
3333 assert(!obj->is_forwarded(), "invariant" );
3334 assert(region_attr.is_humongous(),
3335 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3336 _g1h->set_humongous_is_live(obj);
3337 }
3338 }
3339};
3340
3341// Copying Keep Alive closure - can be called from both
3342// serial and parallel code as long as different worker
3343// threads utilize different G1ParScanThreadState instances
3344// and different queues.
3345
3346class G1CopyingKeepAliveClosure: public OopClosure {
3347 G1CollectedHeap* _g1h;
3348 G1ParScanThreadState* _par_scan_state;
3349
3350public:
3351 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3352 G1ParScanThreadState* pss):
3353 _g1h(g1h),
3354 _par_scan_state(pss)
3355 {}
3356
3357 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3358 virtual void do_oop( oop* p) { do_oop_work(p); }
3359
3360 template <class T> void do_oop_work(T* p) {
3361 oop obj = RawAccess<>::oop_load(p);
3362
3363 if (_g1h->is_in_cset_or_humongous(obj)) {
3364 // If the referent object has been forwarded (either copied
3365 // to a new location or to itself in the event of an
3366 // evacuation failure) then we need to update the reference
3367 // field and, if both reference and referent are in the G1
3368 // heap, update the RSet for the referent.
3369 //
3370 // If the referent has not been forwarded then we have to keep
3371 // it alive by policy. Therefore we have copy the referent.
3372 //
3373 // When the queue is drained (after each phase of reference processing)
3374 // the object and it's followers will be copied, the reference field set
3375 // to point to the new location, and the RSet updated.
3376 _par_scan_state->push_on_queue(p);
3377 }
3378 }
3379};
3380
3381// Serial drain queue closure. Called as the 'complete_gc'
3382// closure for each discovered list in some of the
3383// reference processing phases.
3384
3385class G1STWDrainQueueClosure: public VoidClosure {
3386protected:
3387 G1CollectedHeap* _g1h;
3388 G1ParScanThreadState* _par_scan_state;
3389
3390 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3391
3392public:
3393 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3394 _g1h(g1h),
3395 _par_scan_state(pss)
3396 { }
3397
3398 void do_void() {
3399 G1ParScanThreadState* const pss = par_scan_state();
3400 pss->trim_queue();
3401 }
3402};
3403
3404// Parallel Reference Processing closures
3405
3406// Implementation of AbstractRefProcTaskExecutor for parallel reference
3407// processing during G1 evacuation pauses.
3408
3409class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3410private:
3411 G1CollectedHeap* _g1h;
3412 G1ParScanThreadStateSet* _pss;
3413 RefToScanQueueSet* _queues;
3414 WorkGang* _workers;
3415
3416public:
3417 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3418 G1ParScanThreadStateSet* per_thread_states,
3419 WorkGang* workers,
3420 RefToScanQueueSet *task_queues) :
3421 _g1h(g1h),
3422 _pss(per_thread_states),
3423 _queues(task_queues),
3424 _workers(workers)
3425 {
3426 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3427 }
3428
3429 // Executes the given task using concurrent marking worker threads.
3430 virtual void execute(ProcessTask& task, uint ergo_workers);
3431};
3432
3433// Gang task for possibly parallel reference processing
3434
3435class G1STWRefProcTaskProxy: public AbstractGangTask {
3436 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3437 ProcessTask& _proc_task;
3438 G1CollectedHeap* _g1h;
3439 G1ParScanThreadStateSet* _pss;
3440 RefToScanQueueSet* _task_queues;
3441 ParallelTaskTerminator* _terminator;
3442
3443public:
3444 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3445 G1CollectedHeap* g1h,
3446 G1ParScanThreadStateSet* per_thread_states,
3447 RefToScanQueueSet *task_queues,
3448 ParallelTaskTerminator* terminator) :
3449 AbstractGangTask("Process reference objects in parallel"),
3450 _proc_task(proc_task),
3451 _g1h(g1h),
3452 _pss(per_thread_states),
3453 _task_queues(task_queues),
3454 _terminator(terminator)
3455 {}
3456
3457 virtual void work(uint worker_id) {
3458 // The reference processing task executed by a single worker.
3459 ResourceMark rm;
3460 HandleMark hm;
3461
3462 G1STWIsAliveClosure is_alive(_g1h);
3463
3464 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3465 pss->set_ref_discoverer(NULL);
3466
3467 // Keep alive closure.
3468 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3469
3470 // Complete GC closure
3471 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3472
3473 // Call the reference processing task's work routine.
3474 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3475
3476 // Note we cannot assert that the refs array is empty here as not all
3477 // of the processing tasks (specifically phase2 - pp2_work) execute
3478 // the complete_gc closure (which ordinarily would drain the queue) so
3479 // the queue may not be empty.
3480 }
3481};
3482
3483// Driver routine for parallel reference processing.
3484// Creates an instance of the ref processing gang
3485// task and has the worker threads execute it.
3486void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3487 assert(_workers != NULL, "Need parallel worker threads.");
3488
3489 assert(_workers->active_workers() >= ergo_workers,
3490 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3491 ergo_workers, _workers->active_workers());
3492 TaskTerminator terminator(ergo_workers, _queues);
3493 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3494
3495 _workers->run_task(&proc_task_proxy, ergo_workers);
3496}
3497
3498// End of weak reference support closures
3499
3500void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3501 double ref_proc_start = os::elapsedTime();
3502
3503 ReferenceProcessor* rp = _ref_processor_stw;
3504 assert(rp->discovery_enabled(), "should have been enabled");
3505
3506 // Closure to test whether a referent is alive.
3507 G1STWIsAliveClosure is_alive(this);
3508
3509 // Even when parallel reference processing is enabled, the processing
3510 // of JNI refs is serial and performed serially by the current thread
3511 // rather than by a worker. The following PSS will be used for processing
3512 // JNI refs.
3513
3514 // Use only a single queue for this PSS.
3515 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3516 pss->set_ref_discoverer(NULL);
3517 assert(pss->queue_is_empty(), "pre-condition");
3518
3519 // Keep alive closure.
3520 G1CopyingKeepAliveClosure keep_alive(this, pss);
3521
3522 // Serial Complete GC closure
3523 G1STWDrainQueueClosure drain_queue(this, pss);
3524
3525 // Setup the soft refs policy...
3526 rp->setup_policy(false);
3527
3528 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3529
3530 ReferenceProcessorStats stats;
3531 if (!rp->processing_is_mt()) {
3532 // Serial reference processing...
3533 stats = rp->process_discovered_references(&is_alive,
3534 &keep_alive,
3535 &drain_queue,
3536 NULL,
3537 pt);
3538 } else {
3539 uint no_of_gc_workers = workers()->active_workers();
3540
3541 // Parallel reference processing
3542 assert(no_of_gc_workers <= rp->max_num_queues(),
3543 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3544 no_of_gc_workers, rp->max_num_queues());
3545
3546 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3547 stats = rp->process_discovered_references(&is_alive,
3548 &keep_alive,
3549 &drain_queue,
3550 &par_task_executor,
3551 pt);
3552 }
3553
3554 _gc_tracer_stw->report_gc_reference_stats(stats);
3555
3556 // We have completed copying any necessary live referent objects.
3557 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3558
3559 make_pending_list_reachable();
3560
3561 assert(!rp->discovery_enabled(), "Postcondition");
3562 rp->verify_no_references_recorded();
3563
3564 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3565 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3566}
3567
3568void G1CollectedHeap::make_pending_list_reachable() {
3569 if (collector_state()->in_initial_mark_gc()) {
3570 oop pll_head = Universe::reference_pending_list();
3571 if (pll_head != NULL) {
3572 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3573 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3574 }
3575 }
3576}
3577
3578void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3579 double merge_pss_time_start = os::elapsedTime();
3580 per_thread_states->flush();
3581 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3582}
3583
3584void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) {
3585 _expand_heap_after_alloc_failure = true;
3586 _evacuation_failed = false;
3587
3588 // Disable the hot card cache.
3589 _hot_card_cache->reset_hot_cache_claimed_index();
3590 _hot_card_cache->set_use_cache(false);
3591
3592 // Initialize the GC alloc regions.
3593 _allocator->init_gc_alloc_regions(evacuation_info);
3594
3595 register_regions_with_region_attr();
3596 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3597
3598 rem_set()->prepare_for_scan_rem_set();
3599 _preserved_marks_set.assert_empty();
3600
3601#if COMPILER2_OR_JVMCI
3602 DerivedPointerTable::clear();
3603#endif
3604
3605 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3606 if (collector_state()->in_initial_mark_gc()) {
3607 concurrent_mark()->pre_initial_mark();
3608
3609 double start_clear_claimed_marks = os::elapsedTime();
3610
3611 ClassLoaderDataGraph::clear_claimed_marks();
3612
3613 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3614 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3615 }
3616
3617 // Should G1EvacuationFailureALot be in effect for this GC?
3618 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3619
3620 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3621}
3622
3623class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3624protected:
3625 G1CollectedHeap* _g1h;
3626 G1ParScanThreadStateSet* _per_thread_states;
3627 RefToScanQueueSet* _task_queues;
3628 TaskTerminator _terminator;
3629 uint _num_workers;
3630
3631 void evacuate_live_objects(G1ParScanThreadState* pss,
3632 uint worker_id,
3633 G1GCPhaseTimes::GCParPhases objcopy_phase,
3634 G1GCPhaseTimes::GCParPhases termination_phase) {
3635 G1GCPhaseTimes* p = _g1h->phase_times();
3636
3637 Ticks start = Ticks::now();
3638 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3639 cl.do_void();
3640
3641 assert(pss->queue_is_empty(), "should be empty");
3642
3643 Tickspan evac_time = (Ticks::now() - start);
3644 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3645
3646 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3647 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3648
3649 if (termination_phase == G1GCPhaseTimes::Termination) {
3650 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3651 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3652 } else {
3653 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3654 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3655 }
3656 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3657 }
3658
3659 virtual void start_work(uint worker_id) { }
3660
3661 virtual void end_work(uint worker_id) { }
3662
3663 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3664
3665 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3666
3667public:
3668 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3669 AbstractGangTask(name),
3670 _g1h(G1CollectedHeap::heap()),
3671 _per_thread_states(per_thread_states),
3672 _task_queues(task_queues),
3673 _terminator(num_workers, _task_queues),
3674 _num_workers(num_workers)
3675 { }
3676
3677 void work(uint worker_id) {
3678 start_work(worker_id);
3679
3680 {
3681 ResourceMark rm;
3682 HandleMark hm;
3683
3684 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3685 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3686
3687 scan_roots(pss, worker_id);
3688 evacuate_live_objects(pss, worker_id);
3689 }
3690
3691 end_work(worker_id);
3692 }
3693};
3694
3695class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3696 G1RootProcessor* _root_processor;
3697
3698 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3699 _root_processor->evacuate_roots(pss, worker_id);
3700 _g1h->rem_set()->update_rem_set(pss, worker_id);
3701 _g1h->rem_set()->scan_rem_set(pss, worker_id, G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::CodeRoots);
3702 }
3703
3704 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3705 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3706 }
3707
3708 void start_work(uint worker_id) {
3709 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3710 }
3711
3712 void end_work(uint worker_id) {
3713 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3714 }
3715
3716public:
3717 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3718 G1ParScanThreadStateSet* per_thread_states,
3719 RefToScanQueueSet* task_queues,
3720 G1RootProcessor* root_processor,
3721 uint num_workers) :
3722 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3723 _root_processor(root_processor)
3724 { }
3725};
3726
3727void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3728 Tickspan task_time;
3729 const uint num_workers = workers()->active_workers();
3730
3731 Ticks start_processing = Ticks::now();
3732 {
3733 G1RootProcessor root_processor(this, num_workers);
3734 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3735 task_time = run_task(&g1_par_task);
3736 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3737 // To extract its code root fixup time we measure total time of this scope and
3738 // subtract from the time the WorkGang task took.
3739 }
3740 Tickspan total_processing = Ticks::now() - start_processing;
3741
3742 G1GCPhaseTimes* p = phase_times();
3743 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3744 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3745}
3746
3747class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3748
3749 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3750 _g1h->rem_set()->scan_rem_set(pss, worker_id, G1GCPhaseTimes::OptScanRS, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptCodeRoots);
3751 }
3752
3753 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3754 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3755 }
3756
3757public:
3758 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3759 RefToScanQueueSet* queues,
3760 uint num_workers) :
3761 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3762 }
3763};
3764
3765void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3766 class G1MarkScope : public MarkScope { };
3767
3768 Tickspan task_time;
3769
3770 Ticks start_processing = Ticks::now();
3771 {
3772 G1MarkScope code_mark_scope;
3773 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3774 task_time = run_task(&task);
3775 // See comment in evacuate_collection_set() for the reason of the scope.
3776 }
3777 Tickspan total_processing = Ticks::now() - start_processing;
3778
3779 G1GCPhaseTimes* p = phase_times();
3780 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3781}
3782
3783void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3784 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3785
3786 Ticks start = Ticks::now();
3787
3788 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3789
3790 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3791 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3792
3793 if (time_left_ms < 0 ||
3794 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3795 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3796 _collection_set.optional_region_length(), time_left_ms);
3797 break;
3798 }
3799
3800 evacuate_next_optional_regions(per_thread_states);
3801 }
3802
3803 _collection_set.abandon_optional_collection_set(per_thread_states);
3804
3805 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3806}
3807
3808void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3809 // Also cleans the card table from temporary duplicate detection information used
3810 // during UpdateRS/ScanRS.
3811 rem_set()->cleanup_after_scan_rem_set();
3812
3813 // Process any discovered reference objects - we have
3814 // to do this _before_ we retire the GC alloc regions
3815 // as we may have to copy some 'reachable' referent
3816 // objects (and their reachable sub-graphs) that were
3817 // not copied during the pause.
3818 process_discovered_references(per_thread_states);
3819
3820 G1STWIsAliveClosure is_alive(this);
3821 G1KeepAliveClosure keep_alive(this);
3822
3823 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3824 phase_times()->weak_phase_times());
3825
3826 if (G1StringDedup::is_enabled()) {
3827 double string_dedup_time_ms = os::elapsedTime();
3828
3829 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3830
3831 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3832 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3833 }
3834
3835 _allocator->release_gc_alloc_regions(evacuation_info);
3836
3837 if (evacuation_failed()) {
3838 restore_after_evac_failure();
3839
3840 // Reset the G1EvacuationFailureALot counters and flags
3841 NOT_PRODUCT(reset_evacuation_should_fail();)
3842
3843 double recalculate_used_start = os::elapsedTime();
3844 set_used(recalculate_used());
3845 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3846
3847 if (_archive_allocator != NULL) {
3848 _archive_allocator->clear_used();
3849 }
3850 for (uint i = 0; i < ParallelGCThreads; i++) {
3851 if (_evacuation_failed_info_array[i].has_failed()) {
3852 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3853 }
3854 }
3855 } else {
3856 // The "used" of the the collection set have already been subtracted
3857 // when they were freed. Add in the bytes evacuated.
3858 increase_used(policy()->bytes_copied_during_gc());
3859 }
3860
3861 _preserved_marks_set.assert_empty();
3862
3863 merge_per_thread_state_info(per_thread_states);
3864
3865 // Reset and re-enable the hot card cache.
3866 // Note the counts for the cards in the regions in the
3867 // collection set are reset when the collection set is freed.
3868 _hot_card_cache->reset_hot_cache();
3869 _hot_card_cache->set_use_cache(true);
3870
3871 purge_code_root_memory();
3872
3873 redirty_logged_cards();
3874
3875 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3876
3877 eagerly_reclaim_humongous_regions();
3878
3879 record_obj_copy_mem_stats();
3880
3881 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3882 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3883
3884#if COMPILER2_OR_JVMCI
3885 double start = os::elapsedTime();
3886 DerivedPointerTable::update_pointers();
3887 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3888#endif
3889 policy()->print_age_table();
3890}
3891
3892void G1CollectedHeap::record_obj_copy_mem_stats() {
3893 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3894
3895 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3896 create_g1_evac_summary(&_old_evac_stats));
3897}
3898
3899void G1CollectedHeap::free_region(HeapRegion* hr,
3900 FreeRegionList* free_list,
3901 bool skip_remset,
3902 bool skip_hot_card_cache,
3903 bool locked) {
3904 assert(!hr->is_free(), "the region should not be free");
3905 assert(!hr->is_empty(), "the region should not be empty");
3906 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3907 assert(free_list != NULL, "pre-condition");
3908
3909 if (G1VerifyBitmaps) {
3910 MemRegion mr(hr->bottom(), hr->end());
3911 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3912 }
3913
3914 // Clear the card counts for this region.
3915 // Note: we only need to do this if the region is not young
3916 // (since we don't refine cards in young regions).
3917 if (!skip_hot_card_cache && !hr->is_young()) {
3918 _hot_card_cache->reset_card_counts(hr);
3919 }
3920 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3921 _policy->remset_tracker()->update_at_free(hr);
3922 free_list->add_ordered(hr);
3923}
3924
3925void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3926 FreeRegionList* free_list) {
3927 assert(hr->is_humongous(), "this is only for humongous regions");
3928 assert(free_list != NULL, "pre-condition");
3929 hr->clear_humongous();
3930 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3931}
3932
3933void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3934 const uint humongous_regions_removed) {
3935 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3936 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3937 _old_set.bulk_remove(old_regions_removed);
3938 _humongous_set.bulk_remove(humongous_regions_removed);
3939 }
3940
3941}
3942
3943void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3944 assert(list != NULL, "list can't be null");
3945 if (!list->is_empty()) {
3946 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3947 _hrm->insert_list_into_free_list(list);
3948 }
3949}
3950
3951void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3952 decrease_used(bytes);
3953}
3954
3955class G1FreeCollectionSetTask : public AbstractGangTask {
3956private:
3957
3958 // Closure applied to all regions in the collection set to do work that needs to
3959 // be done serially in a single thread.
3960 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3961 private:
3962 G1EvacuationInfo* _evacuation_info;
3963 const size_t* _surviving_young_words;
3964
3965 // Bytes used in successfully evacuated regions before the evacuation.
3966 size_t _before_used_bytes;
3967 // Bytes used in unsucessfully evacuated regions before the evacuation
3968 size_t _after_used_bytes;
3969
3970 size_t _bytes_allocated_in_old_since_last_gc;
3971
3972 size_t _failure_used_words;
3973 size_t _failure_waste_words;
3974
3975 FreeRegionList _local_free_list;
3976 public:
3977 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3978 HeapRegionClosure(),
3979 _evacuation_info(evacuation_info),
3980 _surviving_young_words(surviving_young_words),
3981 _before_used_bytes(0),
3982 _after_used_bytes(0),
3983 _bytes_allocated_in_old_since_last_gc(0),
3984 _failure_used_words(0),
3985 _failure_waste_words(0),
3986 _local_free_list("Local Region List for CSet Freeing") {
3987 }
3988
3989 virtual bool do_heap_region(HeapRegion* r) {
3990 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3991
3992 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3993 g1h->clear_region_attr(r);
3994
3995 if (r->is_young()) {
3996 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3997 "Young index %d is wrong for region %u of type %s with %u young regions",
3998 r->young_index_in_cset(),
3999 r->hrm_index(),
4000 r->get_type_str(),
4001 g1h->collection_set()->young_region_length());
4002 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4003 r->record_surv_words_in_group(words_survived);
4004 }
4005
4006 if (!r->evacuation_failed()) {
4007 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4008 _before_used_bytes += r->used();
4009 g1h->free_region(r,
4010 &_local_free_list,
4011 true, /* skip_remset */
4012 true, /* skip_hot_card_cache */
4013 true /* locked */);
4014 } else {
4015 r->uninstall_surv_rate_group();
4016 r->set_young_index_in_cset(-1);
4017 r->set_evacuation_failed(false);
4018 // When moving a young gen region to old gen, we "allocate" that whole region
4019 // there. This is in addition to any already evacuated objects. Notify the
4020 // policy about that.
4021 // Old gen regions do not cause an additional allocation: both the objects
4022 // still in the region and the ones already moved are accounted for elsewhere.
4023 if (r->is_young()) {
4024 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4025 }
4026 // The region is now considered to be old.
4027 r->set_old();
4028 // Do some allocation statistics accounting. Regions that failed evacuation
4029 // are always made old, so there is no need to update anything in the young
4030 // gen statistics, but we need to update old gen statistics.
4031 size_t used_words = r->marked_bytes() / HeapWordSize;
4032
4033 _failure_used_words += used_words;
4034 _failure_waste_words += HeapRegion::GrainWords - used_words;
4035
4036 g1h->old_set_add(r);
4037 _after_used_bytes += r->used();
4038 }
4039 return false;
4040 }
4041
4042 void complete_work() {
4043 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4044
4045 _evacuation_info->set_regions_freed(_local_free_list.length());
4046 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4047
4048 g1h->prepend_to_freelist(&_local_free_list);
4049 g1h->decrement_summary_bytes(_before_used_bytes);
4050
4051 G1Policy* policy = g1h->policy();
4052 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4053
4054 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4055 }
4056 };
4057
4058 G1CollectionSet* _collection_set;
4059 G1SerialFreeCollectionSetClosure _cl;
4060 const size_t* _surviving_young_words;
4061
4062 size_t _rs_lengths;
4063
4064 volatile jint _serial_work_claim;
4065
4066 struct WorkItem {
4067 uint region_idx;
4068 bool is_young;
4069 bool evacuation_failed;
4070
4071 WorkItem(HeapRegion* r) {
4072 region_idx = r->hrm_index();
4073 is_young = r->is_young();
4074 evacuation_failed = r->evacuation_failed();
4075 }
4076 };
4077
4078 volatile size_t _parallel_work_claim;
4079 size_t _num_work_items;
4080 WorkItem* _work_items;
4081
4082 void do_serial_work() {
4083 // Need to grab the lock to be allowed to modify the old region list.
4084 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4085 _collection_set->iterate(&_cl);
4086 }
4087
4088 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4089 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4090
4091 HeapRegion* r = g1h->region_at(region_idx);
4092 assert(!g1h->is_on_master_free_list(r), "sanity");
4093
4094 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4095
4096 if (!is_young) {
4097 g1h->_hot_card_cache->reset_card_counts(r);
4098 }
4099
4100 if (!evacuation_failed) {
4101 r->rem_set()->clear_locked();
4102 }
4103 }
4104
4105 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4106 private:
4107 size_t _cur_idx;
4108 WorkItem* _work_items;
4109 public:
4110 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4111
4112 virtual bool do_heap_region(HeapRegion* r) {
4113 _work_items[_cur_idx++] = WorkItem(r);
4114 return false;
4115 }
4116 };
4117
4118 void prepare_work() {
4119 G1PrepareFreeCollectionSetClosure cl(_work_items);
4120 _collection_set->iterate(&cl);
4121 }
4122
4123 void complete_work() {
4124 _cl.complete_work();
4125
4126 G1Policy* policy = G1CollectedHeap::heap()->policy();
4127 policy->record_max_rs_lengths(_rs_lengths);
4128 policy->cset_regions_freed();
4129 }
4130public:
4131 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4132 AbstractGangTask("G1 Free Collection Set"),
4133 _collection_set(collection_set),
4134 _cl(evacuation_info, surviving_young_words),
4135 _surviving_young_words(surviving_young_words),
4136 _rs_lengths(0),
4137 _serial_work_claim(0),
4138 _parallel_work_claim(0),
4139 _num_work_items(collection_set->region_length()),
4140 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4141 prepare_work();
4142 }
4143
4144 ~G1FreeCollectionSetTask() {
4145 complete_work();
4146 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4147 }
4148
4149 // Chunk size for work distribution. The chosen value has been determined experimentally
4150 // to be a good tradeoff between overhead and achievable parallelism.
4151 static uint chunk_size() { return 32; }
4152
4153 virtual void work(uint worker_id) {
4154 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4155
4156 // Claim serial work.
4157 if (_serial_work_claim == 0) {
4158 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4159 if (value == 0) {
4160 double serial_time = os::elapsedTime();
4161 do_serial_work();
4162 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4163 }
4164 }
4165
4166 // Start parallel work.
4167 double young_time = 0.0;
4168 bool has_young_time = false;
4169 double non_young_time = 0.0;
4170 bool has_non_young_time = false;
4171
4172 while (true) {
4173 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4174 size_t cur = end - chunk_size();
4175
4176 if (cur >= _num_work_items) {
4177 break;
4178 }
4179
4180 EventGCPhaseParallel event;
4181 double start_time = os::elapsedTime();
4182
4183 end = MIN2(end, _num_work_items);
4184
4185 for (; cur < end; cur++) {
4186 bool is_young = _work_items[cur].is_young;
4187
4188 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4189
4190 double end_time = os::elapsedTime();
4191 double time_taken = end_time - start_time;
4192 if (is_young) {
4193 young_time += time_taken;
4194 has_young_time = true;
4195 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4196 } else {
4197 non_young_time += time_taken;
4198 has_non_young_time = true;
4199 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4200 }
4201 start_time = end_time;
4202 }
4203 }
4204
4205 if (has_young_time) {
4206 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4207 }
4208 if (has_non_young_time) {
4209 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4210 }
4211 }
4212};
4213
4214void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4215 _eden.clear();
4216
4217 double free_cset_start_time = os::elapsedTime();
4218
4219 {
4220 uint const num_regions = _collection_set.region_length();
4221 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4222 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4223
4224 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4225
4226 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4227 cl.name(), num_workers, num_regions);
4228 workers()->run_task(&cl, num_workers);
4229 }
4230 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4231
4232 collection_set->clear();
4233}
4234
4235class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4236 private:
4237 FreeRegionList* _free_region_list;
4238 HeapRegionSet* _proxy_set;
4239 uint _humongous_objects_reclaimed;
4240 uint _humongous_regions_reclaimed;
4241 size_t _freed_bytes;
4242 public:
4243
4244 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4245 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4246 }
4247
4248 virtual bool do_heap_region(HeapRegion* r) {
4249 if (!r->is_starts_humongous()) {
4250 return false;
4251 }
4252
4253 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4254
4255 oop obj = (oop)r->bottom();
4256 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4257
4258 // The following checks whether the humongous object is live are sufficient.
4259 // The main additional check (in addition to having a reference from the roots
4260 // or the young gen) is whether the humongous object has a remembered set entry.
4261 //
4262 // A humongous object cannot be live if there is no remembered set for it
4263 // because:
4264 // - there can be no references from within humongous starts regions referencing
4265 // the object because we never allocate other objects into them.
4266 // (I.e. there are no intra-region references that may be missed by the
4267 // remembered set)
4268 // - as soon there is a remembered set entry to the humongous starts region
4269 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4270 // until the end of a concurrent mark.
4271 //
4272 // It is not required to check whether the object has been found dead by marking
4273 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4274 // all objects allocated during that time are considered live.
4275 // SATB marking is even more conservative than the remembered set.
4276 // So if at this point in the collection there is no remembered set entry,
4277 // nobody has a reference to it.
4278 // At the start of collection we flush all refinement logs, and remembered sets
4279 // are completely up-to-date wrt to references to the humongous object.
4280 //
4281 // Other implementation considerations:
4282 // - never consider object arrays at this time because they would pose
4283 // considerable effort for cleaning up the the remembered sets. This is
4284 // required because stale remembered sets might reference locations that
4285 // are currently allocated into.
4286 uint region_idx = r->hrm_index();
4287 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4288 !r->rem_set()->is_empty()) {
4289 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4290 region_idx,
4291 (size_t)obj->size() * HeapWordSize,
4292 p2i(r->bottom()),
4293 r->rem_set()->occupied(),
4294 r->rem_set()->strong_code_roots_list_length(),
4295 next_bitmap->is_marked(r->bottom()),
4296 g1h->is_humongous_reclaim_candidate(region_idx),
4297 obj->is_typeArray()
4298 );
4299 return false;
4300 }
4301
4302 guarantee(obj->is_typeArray(),
4303 "Only eagerly reclaiming type arrays is supported, but the object "
4304 PTR_FORMAT " is not.", p2i(r->bottom()));
4305
4306 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4307 region_idx,
4308 (size_t)obj->size() * HeapWordSize,
4309 p2i(r->bottom()),
4310 r->rem_set()->occupied(),
4311 r->rem_set()->strong_code_roots_list_length(),
4312 next_bitmap->is_marked(r->bottom()),
4313 g1h->is_humongous_reclaim_candidate(region_idx),
4314 obj->is_typeArray()
4315 );
4316
4317 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4318 cm->humongous_object_eagerly_reclaimed(r);
4319 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4320 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4321 region_idx,
4322 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4323 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4324 _humongous_objects_reclaimed++;
4325 do {
4326 HeapRegion* next = g1h->next_region_in_humongous(r);
4327 _freed_bytes += r->used();
4328 r->set_containing_set(NULL);
4329 _humongous_regions_reclaimed++;
4330 g1h->free_humongous_region(r, _free_region_list);
4331 r = next;
4332 } while (r != NULL);
4333
4334 return false;
4335 }
4336
4337 uint humongous_objects_reclaimed() {
4338 return _humongous_objects_reclaimed;
4339 }
4340
4341 uint humongous_regions_reclaimed() {
4342 return _humongous_regions_reclaimed;
4343 }
4344
4345 size_t bytes_freed() const {
4346 return _freed_bytes;
4347 }
4348};
4349
4350void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4351 assert_at_safepoint_on_vm_thread();
4352
4353 if (!G1EagerReclaimHumongousObjects ||
4354 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4355 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4356 return;
4357 }
4358
4359 double start_time = os::elapsedTime();
4360
4361 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4362
4363 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4364 heap_region_iterate(&cl);
4365
4366 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4367
4368 G1HRPrinter* hrp = hr_printer();
4369 if (hrp->is_active()) {
4370 FreeRegionListIterator iter(&local_cleanup_list);
4371 while (iter.more_available()) {
4372 HeapRegion* hr = iter.get_next();
4373 hrp->cleanup(hr);
4374 }
4375 }
4376
4377 prepend_to_freelist(&local_cleanup_list);
4378 decrement_summary_bytes(cl.bytes_freed());
4379
4380 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4381 cl.humongous_objects_reclaimed());
4382}
4383
4384class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4385public:
4386 virtual bool do_heap_region(HeapRegion* r) {
4387 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4388 G1CollectedHeap::heap()->clear_region_attr(r);
4389 r->set_young_index_in_cset(-1);
4390 return false;
4391 }
4392};
4393
4394void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4395 G1AbandonCollectionSetClosure cl;
4396 collection_set_iterate_all(&cl);
4397
4398 collection_set->clear();
4399 collection_set->stop_incremental_building();
4400}
4401
4402bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4403 return _allocator->is_retained_old_region(hr);
4404}
4405
4406void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4407 _eden.add(hr);
4408 _policy->set_region_eden(hr);
4409}
4410
4411#ifdef ASSERT
4412
4413class NoYoungRegionsClosure: public HeapRegionClosure {
4414private:
4415 bool _success;
4416public:
4417 NoYoungRegionsClosure() : _success(true) { }
4418 bool do_heap_region(HeapRegion* r) {
4419 if (r->is_young()) {
4420 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4421 p2i(r->bottom()), p2i(r->end()));
4422 _success = false;
4423 }
4424 return false;
4425 }
4426 bool success() { return _success; }
4427};
4428
4429bool G1CollectedHeap::check_young_list_empty() {
4430 bool ret = (young_regions_count() == 0);
4431
4432 NoYoungRegionsClosure closure;
4433 heap_region_iterate(&closure);
4434 ret = ret && closure.success();
4435
4436 return ret;
4437}
4438
4439#endif // ASSERT
4440
4441class TearDownRegionSetsClosure : public HeapRegionClosure {
4442 HeapRegionSet *_old_set;
4443
4444public:
4445 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4446
4447 bool do_heap_region(HeapRegion* r) {
4448 if (r->is_old()) {
4449 _old_set->remove(r);
4450 } else if(r->is_young()) {
4451 r->uninstall_surv_rate_group();
4452 } else {
4453 // We ignore free regions, we'll empty the free list afterwards.
4454 // We ignore humongous and archive regions, we're not tearing down these
4455 // sets.
4456 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4457 "it cannot be another type");
4458 }
4459 return false;
4460 }
4461
4462 ~TearDownRegionSetsClosure() {
4463 assert(_old_set->is_empty(), "post-condition");
4464 }
4465};
4466
4467void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4468 assert_at_safepoint_on_vm_thread();
4469
4470 if (!free_list_only) {
4471 TearDownRegionSetsClosure cl(&_old_set);
4472 heap_region_iterate(&cl);
4473
4474 // Note that emptying the _young_list is postponed and instead done as
4475 // the first step when rebuilding the regions sets again. The reason for
4476 // this is that during a full GC string deduplication needs to know if
4477 // a collected region was young or old when the full GC was initiated.
4478 }
4479 _hrm->remove_all_free_regions();
4480}
4481
4482void G1CollectedHeap::increase_used(size_t bytes) {
4483 _summary_bytes_used += bytes;
4484}
4485
4486void G1CollectedHeap::decrease_used(size_t bytes) {
4487 assert(_summary_bytes_used >= bytes,
4488 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4489 _summary_bytes_used, bytes);
4490 _summary_bytes_used -= bytes;
4491}
4492
4493void G1CollectedHeap::set_used(size_t bytes) {
4494 _summary_bytes_used = bytes;
4495}
4496
4497class RebuildRegionSetsClosure : public HeapRegionClosure {
4498private:
4499 bool _free_list_only;
4500
4501 HeapRegionSet* _old_set;
4502 HeapRegionManager* _hrm;
4503
4504 size_t _total_used;
4505
4506public:
4507 RebuildRegionSetsClosure(bool free_list_only,
4508 HeapRegionSet* old_set,
4509 HeapRegionManager* hrm) :
4510 _free_list_only(free_list_only),
4511 _old_set(old_set), _hrm(hrm), _total_used(0) {
4512 assert(_hrm->num_free_regions() == 0, "pre-condition");
4513 if (!free_list_only) {
4514 assert(_old_set->is_empty(), "pre-condition");
4515 }
4516 }
4517
4518 bool do_heap_region(HeapRegion* r) {
4519 if (r->is_empty()) {
4520 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4521 // Add free regions to the free list
4522 r->set_free();
4523 _hrm->insert_into_free_list(r);
4524 } else if (!_free_list_only) {
4525 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4526
4527 if (r->is_archive() || r->is_humongous()) {
4528 // We ignore archive and humongous regions. We left these sets unchanged.
4529 } else {
4530 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4531 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4532 r->move_to_old();
4533 _old_set->add(r);
4534 }
4535 _total_used += r->used();
4536 }
4537
4538 return false;
4539 }
4540
4541 size_t total_used() {
4542 return _total_used;
4543 }
4544};
4545
4546void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4547 assert_at_safepoint_on_vm_thread();
4548
4549 if (!free_list_only) {
4550 _eden.clear();
4551 _survivor.clear();
4552 }
4553
4554 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4555 heap_region_iterate(&cl);
4556
4557 if (!free_list_only) {
4558 set_used(cl.total_used());
4559 if (_archive_allocator != NULL) {
4560 _archive_allocator->clear_used();
4561 }
4562 }
4563 assert_used_and_recalculate_used_equal(this);
4564}
4565
4566// Methods for the mutator alloc region
4567
4568HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4569 bool force) {
4570 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4571 bool should_allocate = policy()->should_allocate_mutator_region();
4572 if (force || should_allocate) {
4573 HeapRegion* new_alloc_region = new_region(word_size,
4574 HeapRegionType::Eden,
4575 false /* do_expand */);
4576 if (new_alloc_region != NULL) {
4577 set_region_short_lived_locked(new_alloc_region);
4578 _hr_printer.alloc(new_alloc_region, !should_allocate);
4579 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4580 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4581 return new_alloc_region;
4582 }
4583 }
4584 return NULL;
4585}
4586
4587void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4588 size_t allocated_bytes) {
4589 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4590 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4591
4592 collection_set()->add_eden_region(alloc_region);
4593 increase_used(allocated_bytes);
4594 _eden.add_used_bytes(allocated_bytes);
4595 _hr_printer.retire(alloc_region);
4596
4597 // We update the eden sizes here, when the region is retired,
4598 // instead of when it's allocated, since this is the point that its
4599 // used space has been recorded in _summary_bytes_used.
4600 g1mm()->update_eden_size();
4601}
4602
4603// Methods for the GC alloc regions
4604
4605bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4606 if (dest.is_old()) {
4607 return true;
4608 } else {
4609 return survivor_regions_count() < policy()->max_survivor_regions();
4610 }
4611}
4612
4613HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4614 assert(FreeList_lock->owned_by_self(), "pre-condition");
4615
4616 if (!has_more_regions(dest)) {
4617 return NULL;
4618 }
4619
4620 HeapRegionType type;
4621 if (dest.is_young()) {
4622 type = HeapRegionType::Survivor;
4623 } else {
4624 type = HeapRegionType::Old;
4625 }
4626
4627 HeapRegion* new_alloc_region = new_region(word_size,
4628 type,
4629 true /* do_expand */);
4630
4631 if (new_alloc_region != NULL) {
4632 if (type.is_survivor()) {
4633 new_alloc_region->set_survivor();
4634 _survivor.add(new_alloc_region);
4635 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4636 } else {
4637 new_alloc_region->set_old();
4638 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4639 }
4640 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4641 register_region_with_region_attr(new_alloc_region);
4642 _hr_printer.alloc(new_alloc_region);
4643 return new_alloc_region;
4644 }
4645 return NULL;
4646}
4647
4648void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4649 size_t allocated_bytes,
4650 G1HeapRegionAttr dest) {
4651 policy()->record_bytes_copied_during_gc(allocated_bytes);
4652 if (dest.is_old()) {
4653 old_set_add(alloc_region);
4654 } else {
4655 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4656 _survivor.add_used_bytes(allocated_bytes);
4657 }
4658
4659 bool const during_im = collector_state()->in_initial_mark_gc();
4660 if (during_im && allocated_bytes > 0) {
4661 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4662 }
4663 _hr_printer.retire(alloc_region);
4664}
4665
4666HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4667 bool expanded = false;
4668 uint index = _hrm->find_highest_free(&expanded);
4669
4670 if (index != G1_NO_HRM_INDEX) {
4671 if (expanded) {
4672 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4673 HeapRegion::GrainWords * HeapWordSize);
4674 }
4675 _hrm->allocate_free_regions_starting_at(index, 1);
4676 return region_at(index);
4677 }
4678 return NULL;
4679}
4680
4681// Optimized nmethod scanning
4682
4683class RegisterNMethodOopClosure: public OopClosure {
4684 G1CollectedHeap* _g1h;
4685 nmethod* _nm;
4686
4687 template <class T> void do_oop_work(T* p) {
4688 T heap_oop = RawAccess<>::oop_load(p);
4689 if (!CompressedOops::is_null(heap_oop)) {
4690 oop obj = CompressedOops::decode_not_null(heap_oop);
4691 HeapRegion* hr = _g1h->heap_region_containing(obj);
4692 assert(!hr->is_continues_humongous(),
4693 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4694 " starting at " HR_FORMAT,
4695 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4696
4697 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4698 hr->add_strong_code_root_locked(_nm);
4699 }
4700 }
4701
4702public:
4703 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4704 _g1h(g1h), _nm(nm) {}
4705
4706 void do_oop(oop* p) { do_oop_work(p); }
4707 void do_oop(narrowOop* p) { do_oop_work(p); }
4708};
4709
4710class UnregisterNMethodOopClosure: public OopClosure {
4711 G1CollectedHeap* _g1h;
4712 nmethod* _nm;
4713
4714 template <class T> void do_oop_work(T* p) {
4715 T heap_oop = RawAccess<>::oop_load(p);
4716 if (!CompressedOops::is_null(heap_oop)) {
4717 oop obj = CompressedOops::decode_not_null(heap_oop);
4718 HeapRegion* hr = _g1h->heap_region_containing(obj);
4719 assert(!hr->is_continues_humongous(),
4720 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4721 " starting at " HR_FORMAT,
4722 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4723
4724 hr->remove_strong_code_root(_nm);
4725 }
4726 }
4727
4728public:
4729 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4730 _g1h(g1h), _nm(nm) {}
4731
4732 void do_oop(oop* p) { do_oop_work(p); }
4733 void do_oop(narrowOop* p) { do_oop_work(p); }
4734};
4735
4736void G1CollectedHeap::register_nmethod(nmethod* nm) {
4737 guarantee(nm != NULL, "sanity");
4738 RegisterNMethodOopClosure reg_cl(this, nm);
4739 nm->oops_do(&reg_cl);
4740}
4741
4742void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4743 guarantee(nm != NULL, "sanity");
4744 UnregisterNMethodOopClosure reg_cl(this, nm);
4745 nm->oops_do(&reg_cl, true);
4746}
4747
4748void G1CollectedHeap::purge_code_root_memory() {
4749 double purge_start = os::elapsedTime();
4750 G1CodeRootSet::purge();
4751 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4752 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4753}
4754
4755class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4756 G1CollectedHeap* _g1h;
4757
4758public:
4759 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4760 _g1h(g1h) {}
4761
4762 void do_code_blob(CodeBlob* cb) {
4763 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4764 if (nm == NULL) {
4765 return;
4766 }
4767
4768 _g1h->register_nmethod(nm);
4769 }
4770};
4771
4772void G1CollectedHeap::rebuild_strong_code_roots() {
4773 RebuildStrongCodeRootClosure blob_cl(this);
4774 CodeCache::blobs_do(&blob_cl);
4775}
4776
4777void G1CollectedHeap::initialize_serviceability() {
4778 _g1mm->initialize_serviceability();
4779}
4780
4781MemoryUsage G1CollectedHeap::memory_usage() {
4782 return _g1mm->memory_usage();
4783}
4784
4785GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4786 return _g1mm->memory_managers();
4787}
4788
4789GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4790 return _g1mm->memory_pools();
4791}
4792