1 /*
2 * Copyright (c) 2001, 2020, 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/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
45 #include "gc/g1/g1GCPhaseTimes.hpp"
46 #include "gc/g1/g1HeapSizingPolicy.hpp"
47 #include "gc/g1/g1HeapTransition.hpp"
48 #include "gc/g1/g1HeapVerifier.hpp"
49 #include "gc/g1/g1HotCardCache.hpp"
50 #include "gc/g1/g1InitLogger.hpp"
51 #include "gc/g1/g1MemoryPool.hpp"
52 #include "gc/g1/g1OopClosures.inline.hpp"
53 #include "gc/g1/g1ParallelCleaning.hpp"
54 #include "gc/g1/g1ParScanThreadState.inline.hpp"
55 #include "gc/g1/g1Policy.hpp"
56 #include "gc/g1/g1RedirtyCardsQueue.hpp"
57 #include "gc/g1/g1RegionToSpaceMapper.hpp"
58 #include "gc/g1/g1RemSet.hpp"
59 #include "gc/g1/g1RootClosures.hpp"
60 #include "gc/g1/g1RootProcessor.hpp"
61 #include "gc/g1/g1SATBMarkQueueSet.hpp"
62 #include "gc/g1/g1StringDedup.hpp"
63 #include "gc/g1/g1ThreadLocalData.hpp"
64 #include "gc/g1/g1Trace.hpp"
65 #include "gc/g1/g1YCTypes.hpp"
66 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
67 #include "gc/g1/g1VMOperations.hpp"
68 #include "gc/g1/heapRegion.inline.hpp"
69 #include "gc/g1/heapRegionRemSet.hpp"
70 #include "gc/g1/heapRegionSet.inline.hpp"
71 #include "gc/shared/concurrentGCBreakpoints.hpp"
72 #include "gc/shared/gcBehaviours.hpp"
73 #include "gc/shared/gcHeapSummary.hpp"
74 #include "gc/shared/gcId.hpp"
75 #include "gc/shared/gcLocker.hpp"
76 #include "gc/shared/gcTimer.hpp"
77 #include "gc/shared/gcTraceTime.inline.hpp"
78 #include "gc/shared/generationSpec.hpp"
79 #include "gc/shared/isGCActiveMark.hpp"
80 #include "gc/shared/locationPrinter.inline.hpp"
81 #include "gc/shared/oopStorageParState.hpp"
82 #include "gc/shared/preservedMarks.inline.hpp"
83 #include "gc/shared/suspendibleThreadSet.hpp"
84 #include "gc/shared/referenceProcessor.inline.hpp"
85 #include "gc/shared/taskTerminator.hpp"
86 #include "gc/shared/taskqueue.inline.hpp"
87 #include "gc/shared/weakProcessor.inline.hpp"
88 #include "gc/shared/workerPolicy.hpp"
89 #include "logging/log.hpp"
90 #include "memory/allocation.hpp"
91 #include "memory/iterator.hpp"
92 #include "memory/heapInspection.hpp"
93 #include "memory/resourceArea.hpp"
94 #include "memory/universe.hpp"
95 #include "oops/access.inline.hpp"
96 #include "oops/compressedOops.inline.hpp"
97 #include "oops/oop.inline.hpp"
98 #include "runtime/atomic.hpp"
99 #include "runtime/handles.inline.hpp"
100 #include "runtime/init.hpp"
101 #include "runtime/orderAccess.hpp"
102 #include "runtime/threadSMR.hpp"
103 #include "runtime/vmThread.hpp"
104 #include "utilities/align.hpp"
105 #include "utilities/autoRestore.hpp"
106 #include "utilities/bitMap.inline.hpp"
107 #include "utilities/globalDefinitions.hpp"
108 #include "utilities/stack.inline.hpp"
109
110 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
111
112 // INVARIANTS/NOTES
113 //
114 // All allocation activity covered by the G1CollectedHeap interface is
115 // serialized by acquiring the HeapLock. This happens in mem_allocate
116 // and allocate_new_tlab, which are the "entry" points to the
117 // allocation code from the rest of the JVM. (Note that this does not
118 // apply to TLAB allocation, which is not part of this interface: it
119 // is done by clients of this interface.)
120
121 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
122 private:
123 size_t _num_dirtied;
124 G1CollectedHeap* _g1h;
125 G1CardTable* _g1_ct;
126
127 HeapRegion* region_for_card(CardValue* card_ptr) const {
128 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
129 }
130
131 bool will_become_free(HeapRegion* hr) const {
132 // A region will be freed by free_collection_set if the region is in the
133 // collection set and has not had an evacuation failure.
134 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
135 }
136
137 public:
138 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
139 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
140
141 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
142 HeapRegion* hr = region_for_card(card_ptr);
143
144 // Should only dirty cards in regions that won't be freed.
145 if (!will_become_free(hr)) {
146 *card_ptr = G1CardTable::dirty_card_val();
147 _num_dirtied++;
148 }
149 }
150
151 size_t num_dirtied() const { return _num_dirtied; }
152 };
153
154
155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
156 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
157 }
158
159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
160 // The from card cache is not the memory that is actually committed. So we cannot
161 // take advantage of the zero_filled parameter.
162 reset_from_card_cache(start_idx, num_regions);
163 }
164
165 Tickspan G1CollectedHeap::run_task_timed(AbstractGangTask* task) {
166 Ticks start = Ticks::now();
167 workers()->run_task(task);
168 return Ticks::now() - start;
169 }
170
171 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
172 MemRegion mr) {
173 return new HeapRegion(hrs_index, bot(), mr);
174 }
175
176 // Private methods.
177
178 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
179 HeapRegionType type,
180 bool do_expand,
181 uint node_index) {
182 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
183 "the only time we use this to allocate a humongous region is "
184 "when we are allocating a single humongous region");
185
186 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
187
188 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
189 // Currently, only attempts to allocate GC alloc regions set
190 // do_expand to true. So, we should only reach here during a
191 // safepoint. If this assumption changes we might have to
192 // reconsider the use of _expand_heap_after_alloc_failure.
193 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
194
195 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
196 word_size * HeapWordSize);
197
198 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
199 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
200 word_size * HeapWordSize);
201 if (expand_single_region(node_index)) {
202 // Given that expand_single_region() succeeded in expanding the heap, and we
203 // always expand the heap by an amount aligned to the heap
204 // region size, the free list should in theory not be empty.
205 // In either case allocate_free_region() will check for NULL.
206 res = _hrm->allocate_free_region(type, node_index);
207 } else {
208 _expand_heap_after_alloc_failure = false;
209 }
210 }
211 return res;
212 }
213
214 HeapWord*
215 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
216 uint num_regions,
217 size_t word_size) {
218 assert(first_hr != NULL, "pre-condition");
219 assert(is_humongous(word_size), "word_size should be humongous");
220 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
221
222 // Index of last region in the series.
223 uint first = first_hr->hrm_index();
224 uint last = first + num_regions - 1;
225
226 // We need to initialize the region(s) we just discovered. This is
227 // a bit tricky given that it can happen concurrently with
228 // refinement threads refining cards on these regions and
229 // potentially wanting to refine the BOT as they are scanning
230 // those cards (this can happen shortly after a cleanup; see CR
231 // 6991377). So we have to set up the region(s) carefully and in
232 // a specific order.
233
234 // The word size sum of all the regions we will allocate.
235 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
236 assert(word_size <= word_size_sum, "sanity");
237
238 // The passed in hr will be the "starts humongous" region. The header
239 // of the new object will be placed at the bottom of this region.
240 HeapWord* new_obj = first_hr->bottom();
241 // This will be the new top of the new object.
242 HeapWord* obj_top = new_obj + word_size;
243
244 // First, we need to zero the header of the space that we will be
245 // allocating. When we update top further down, some refinement
246 // threads might try to scan the region. By zeroing the header we
247 // ensure that any thread that will try to scan the region will
248 // come across the zero klass word and bail out.
249 //
250 // NOTE: It would not have been correct to have used
251 // CollectedHeap::fill_with_object() and make the space look like
252 // an int array. The thread that is doing the allocation will
253 // later update the object header to a potentially different array
254 // type and, for a very short period of time, the klass and length
255 // fields will be inconsistent. This could cause a refinement
256 // thread to calculate the object size incorrectly.
257 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
258
259 // Next, pad out the unused tail of the last region with filler
260 // objects, for improved usage accounting.
261 // How many words we use for filler objects.
262 size_t word_fill_size = word_size_sum - word_size;
263
264 // How many words memory we "waste" which cannot hold a filler object.
265 size_t words_not_fillable = 0;
266
267 if (word_fill_size >= min_fill_size()) {
268 fill_with_objects(obj_top, word_fill_size);
269 } else if (word_fill_size > 0) {
270 // We have space to fill, but we cannot fit an object there.
271 words_not_fillable = word_fill_size;
272 word_fill_size = 0;
273 }
274
275 // We will set up the first region as "starts humongous". This
276 // will also update the BOT covering all the regions to reflect
277 // that there is a single object that starts at the bottom of the
278 // first region.
279 first_hr->set_starts_humongous(obj_top, word_fill_size);
280 _policy->remset_tracker()->update_at_allocate(first_hr);
281 // Then, if there are any, we will set up the "continues
282 // humongous" regions.
283 HeapRegion* hr = NULL;
284 for (uint i = first + 1; i <= last; ++i) {
285 hr = region_at(i);
286 hr->set_continues_humongous(first_hr);
287 _policy->remset_tracker()->update_at_allocate(hr);
288 }
289
290 // Up to this point no concurrent thread would have been able to
291 // do any scanning on any region in this series. All the top
292 // fields still point to bottom, so the intersection between
293 // [bottom,top] and [card_start,card_end] will be empty. Before we
294 // update the top fields, we'll do a storestore to make sure that
295 // no thread sees the update to top before the zeroing of the
296 // object header and the BOT initialization.
297 OrderAccess::storestore();
298
299 // Now, we will update the top fields of the "continues humongous"
300 // regions except the last one.
301 for (uint i = first; i < last; ++i) {
302 hr = region_at(i);
303 hr->set_top(hr->end());
304 }
305
306 hr = region_at(last);
307 // If we cannot fit a filler object, we must set top to the end
308 // of the humongous object, otherwise we cannot iterate the heap
309 // and the BOT will not be complete.
310 hr->set_top(hr->end() - words_not_fillable);
311
312 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
313 "obj_top should be in last region");
314
315 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
316
317 assert(words_not_fillable == 0 ||
318 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
319 "Miscalculation in humongous allocation");
320
321 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
322
323 for (uint i = first; i <= last; ++i) {
324 hr = region_at(i);
325 _humongous_set.add(hr);
326 _hr_printer.alloc(hr);
327 }
328
329 return new_obj;
330 }
331
332 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
333 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
334 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
335 }
336
337 // If could fit into free regions w/o expansion, try.
338 // Otherwise, if can expand, do so.
339 // Otherwise, if using ex regions might help, try with ex given back.
340 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
341 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
342
343 _verifier->verify_region_sets_optional();
344
345 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
346
347 // Policy: First try to allocate a humongous object in the free list.
348 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
349 if (humongous_start == NULL) {
350 // Policy: We could not find enough regions for the humongous object in the
351 // free list. Look through the heap to find a mix of free and uncommitted regions.
352 // If so, expand the heap and allocate the humongous object.
353 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
354 if (humongous_start != NULL) {
355 // We managed to find a region by expanding the heap.
356 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
357 word_size * HeapWordSize);
358 policy()->record_new_heap_size(num_regions());
359 } else {
360 // Policy: Potentially trigger a defragmentation GC.
361 }
362 }
363
364 HeapWord* result = NULL;
365 if (humongous_start != NULL) {
366 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
367 assert(result != NULL, "it should always return a valid result");
368
369 // A successful humongous object allocation changes the used space
370 // information of the old generation so we need to recalculate the
371 // sizes and update the jstat counters here.
372 g1mm()->update_sizes();
373 }
374
375 _verifier->verify_region_sets_optional();
376
377 return result;
378 }
379
380 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
381 size_t requested_size,
382 size_t* actual_size) {
383 assert_heap_not_locked_and_not_at_safepoint();
384 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
385
386 return attempt_allocation(min_size, requested_size, actual_size);
387 }
388
389 HeapWord*
390 G1CollectedHeap::mem_allocate(size_t word_size,
391 bool* gc_overhead_limit_was_exceeded) {
392 assert_heap_not_locked_and_not_at_safepoint();
393
394 if (is_humongous(word_size)) {
395 return attempt_allocation_humongous(word_size);
396 }
397 size_t dummy = 0;
398 return attempt_allocation(word_size, word_size, &dummy);
399 }
400
401 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
402 ResourceMark rm; // For retrieving the thread names in log messages.
403
404 // Make sure you read the note in attempt_allocation_humongous().
405
406 assert_heap_not_locked_and_not_at_safepoint();
407 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
408 "be called for humongous allocation requests");
409
410 // We should only get here after the first-level allocation attempt
411 // (attempt_allocation()) failed to allocate.
412
413 // We will loop until a) we manage to successfully perform the
414 // allocation or b) we successfully schedule a collection which
415 // fails to perform the allocation. b) is the only case when we'll
416 // return NULL.
417 HeapWord* result = NULL;
418 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
419 bool should_try_gc;
420 uint gc_count_before;
421
422 {
423 MutexLocker x(Heap_lock);
424 result = _allocator->attempt_allocation_locked(word_size);
425 if (result != NULL) {
426 return result;
427 }
428
429 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
430 // This is different to when only GCLocker::needs_gc() is set: try to avoid
431 // waiting because the GCLocker is active to not wait too long.
432 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
433 // No need for an ergo message here, can_expand_young_list() does this when
434 // it returns true.
435 result = _allocator->attempt_allocation_force(word_size);
436 if (result != NULL) {
437 return result;
438 }
439 }
440 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
441 // the GCLocker initiated GC has been performed and then retry. This includes
442 // the case when the GC Locker is not active but has not been performed.
443 should_try_gc = !GCLocker::needs_gc();
444 // Read the GC count while still holding the Heap_lock.
445 gc_count_before = total_collections();
446 }
447
448 if (should_try_gc) {
449 bool succeeded;
450 result = do_collection_pause(word_size, gc_count_before, &succeeded,
451 GCCause::_g1_inc_collection_pause);
452 if (result != NULL) {
453 assert(succeeded, "only way to get back a non-NULL result");
454 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
455 Thread::current()->name(), p2i(result));
456 return result;
457 }
458
459 if (succeeded) {
460 // We successfully scheduled a collection which failed to allocate. No
461 // point in trying to allocate further. We'll just return NULL.
462 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
463 SIZE_FORMAT " words", Thread::current()->name(), word_size);
464 return NULL;
465 }
466 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
467 Thread::current()->name(), word_size);
468 } else {
469 // Failed to schedule a collection.
470 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
471 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
472 SIZE_FORMAT " words", Thread::current()->name(), word_size);
473 return NULL;
474 }
475 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
476 // The GCLocker is either active or the GCLocker initiated
477 // GC has not yet been performed. Stall until it is and
478 // then retry the allocation.
479 GCLocker::stall_until_clear();
480 gclocker_retry_count += 1;
481 }
482
483 // We can reach here if we were unsuccessful in scheduling a
484 // collection (because another thread beat us to it) or if we were
485 // stalled due to the GC locker. In either can we should retry the
486 // allocation attempt in case another thread successfully
487 // performed a collection and reclaimed enough space. We do the
488 // first attempt (without holding the Heap_lock) here and the
489 // follow-on attempt will be at the start of the next loop
490 // iteration (after taking the Heap_lock).
491 size_t dummy = 0;
492 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
493 if (result != NULL) {
494 return result;
495 }
496
497 // Give a warning if we seem to be looping forever.
498 if ((QueuedAllocationWarningCount > 0) &&
499 (try_count % QueuedAllocationWarningCount == 0)) {
500 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
501 Thread::current()->name(), try_count, word_size);
502 }
503 }
504
505 ShouldNotReachHere();
506 return NULL;
507 }
508
509 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
510 assert_at_safepoint_on_vm_thread();
511 if (_archive_allocator == NULL) {
512 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
513 }
514 }
515
516 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
517 // Allocations in archive regions cannot be of a size that would be considered
518 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
519 // may be different at archive-restore time.
520 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
521 }
522
523 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
524 assert_at_safepoint_on_vm_thread();
525 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
526 if (is_archive_alloc_too_large(word_size)) {
527 return NULL;
528 }
529 return _archive_allocator->archive_mem_allocate(word_size);
530 }
531
532 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
533 size_t end_alignment_in_bytes) {
534 assert_at_safepoint_on_vm_thread();
535 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
536
537 // Call complete_archive to do the real work, filling in the MemRegion
538 // array with the archive regions.
539 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
540 delete _archive_allocator;
541 _archive_allocator = NULL;
542 }
543
544 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
545 assert(ranges != NULL, "MemRegion array NULL");
546 assert(count != 0, "No MemRegions provided");
547 MemRegion reserved = _hrm->reserved();
548 for (size_t i = 0; i < count; i++) {
549 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
550 return false;
551 }
552 }
553 return true;
554 }
555
556 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
557 size_t count,
558 bool open) {
559 assert(!is_init_completed(), "Expect to be called at JVM init time");
560 assert(ranges != NULL, "MemRegion array NULL");
561 assert(count != 0, "No MemRegions provided");
562 MutexLocker x(Heap_lock);
563
564 MemRegion reserved = _hrm->reserved();
565 HeapWord* prev_last_addr = NULL;
566 HeapRegion* prev_last_region = NULL;
567
568 // Temporarily disable pretouching of heap pages. This interface is used
569 // when mmap'ing archived heap data in, so pre-touching is wasted.
570 FlagSetting fs(AlwaysPreTouch, false);
571
572 // Enable archive object checking used by G1MarkSweep. We have to let it know
573 // about each archive range, so that objects in those ranges aren't marked.
574 G1ArchiveAllocator::enable_archive_object_check();
575
576 // For each specified MemRegion range, allocate the corresponding G1
577 // regions and mark them as archive regions. We expect the ranges
578 // in ascending starting address order, without overlap.
579 for (size_t i = 0; i < count; i++) {
580 MemRegion curr_range = ranges[i];
581 HeapWord* start_address = curr_range.start();
582 size_t word_size = curr_range.word_size();
583 HeapWord* last_address = curr_range.last();
584 size_t commits = 0;
585
586 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
587 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
588 p2i(start_address), p2i(last_address));
589 guarantee(start_address > prev_last_addr,
590 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
591 p2i(start_address), p2i(prev_last_addr));
592 prev_last_addr = last_address;
593
594 // Check for ranges that start in the same G1 region in which the previous
595 // range ended, and adjust the start address so we don't try to allocate
596 // the same region again. If the current range is entirely within that
597 // region, skip it, just adjusting the recorded top.
598 HeapRegion* start_region = _hrm->addr_to_region(start_address);
599 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
600 start_address = start_region->end();
601 if (start_address > last_address) {
602 increase_used(word_size * HeapWordSize);
603 start_region->set_top(last_address + 1);
604 continue;
605 }
606 start_region->set_top(start_address);
607 curr_range = MemRegion(start_address, last_address + 1);
608 start_region = _hrm->addr_to_region(start_address);
609 }
610
611 // Perform the actual region allocation, exiting if it fails.
612 // Then note how much new space we have allocated.
613 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
614 return false;
615 }
616 increase_used(word_size * HeapWordSize);
617 if (commits != 0) {
618 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
619 HeapRegion::GrainWords * HeapWordSize * commits);
620
621 }
622
623 // Mark each G1 region touched by the range as archive, add it to
624 // the old set, and set top.
625 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
626 HeapRegion* last_region = _hrm->addr_to_region(last_address);
627 prev_last_region = last_region;
628
629 while (curr_region != NULL) {
630 assert(curr_region->is_empty() && !curr_region->is_pinned(),
631 "Region already in use (index %u)", curr_region->hrm_index());
632 if (open) {
633 curr_region->set_open_archive();
634 } else {
635 curr_region->set_closed_archive();
636 }
637 _hr_printer.alloc(curr_region);
638 _archive_set.add(curr_region);
639 HeapWord* top;
640 HeapRegion* next_region;
641 if (curr_region != last_region) {
642 top = curr_region->end();
643 next_region = _hrm->next_region_in_heap(curr_region);
644 } else {
645 top = last_address + 1;
646 next_region = NULL;
647 }
648 curr_region->set_top(top);
649 curr_region = next_region;
650 }
651
652 // Notify mark-sweep of the archive
653 G1ArchiveAllocator::set_range_archive(curr_range, open);
654 }
655 return true;
656 }
657
658 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
659 assert(!is_init_completed(), "Expect to be called at JVM init time");
660 assert(ranges != NULL, "MemRegion array NULL");
661 assert(count != 0, "No MemRegions provided");
662 MemRegion reserved = _hrm->reserved();
663 HeapWord *prev_last_addr = NULL;
664 HeapRegion* prev_last_region = NULL;
665
666 // For each MemRegion, create filler objects, if needed, in the G1 regions
667 // that contain the address range. The address range actually within the
668 // MemRegion will not be modified. That is assumed to have been initialized
669 // elsewhere, probably via an mmap of archived heap data.
670 MutexLocker x(Heap_lock);
671 for (size_t i = 0; i < count; i++) {
672 HeapWord* start_address = ranges[i].start();
673 HeapWord* last_address = ranges[i].last();
674
675 assert(reserved.contains(start_address) && reserved.contains(last_address),
676 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
677 p2i(start_address), p2i(last_address));
678 assert(start_address > prev_last_addr,
679 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
680 p2i(start_address), p2i(prev_last_addr));
681
682 HeapRegion* start_region = _hrm->addr_to_region(start_address);
683 HeapRegion* last_region = _hrm->addr_to_region(last_address);
684 HeapWord* bottom_address = start_region->bottom();
685
686 // Check for a range beginning in the same region in which the
687 // previous one ended.
688 if (start_region == prev_last_region) {
689 bottom_address = prev_last_addr + 1;
690 }
691
692 // Verify that the regions were all marked as archive regions by
693 // alloc_archive_regions.
694 HeapRegion* curr_region = start_region;
695 while (curr_region != NULL) {
696 guarantee(curr_region->is_archive(),
697 "Expected archive region at index %u", curr_region->hrm_index());
698 if (curr_region != last_region) {
699 curr_region = _hrm->next_region_in_heap(curr_region);
700 } else {
701 curr_region = NULL;
702 }
703 }
704
705 prev_last_addr = last_address;
706 prev_last_region = last_region;
707
708 // Fill the memory below the allocated range with dummy object(s),
709 // if the region bottom does not match the range start, or if the previous
710 // range ended within the same G1 region, and there is a gap.
711 if (start_address != bottom_address) {
712 size_t fill_size = pointer_delta(start_address, bottom_address);
713 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
714 increase_used(fill_size * HeapWordSize);
715 }
716 }
717 }
718
719 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
720 size_t desired_word_size,
721 size_t* actual_word_size) {
722 assert_heap_not_locked_and_not_at_safepoint();
723 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
724 "be called for humongous allocation requests");
725
726 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
727
728 if (result == NULL) {
729 *actual_word_size = desired_word_size;
730 result = attempt_allocation_slow(desired_word_size);
731 }
732
733 assert_heap_not_locked();
734 if (result != NULL) {
735 assert(*actual_word_size != 0, "Actual size must have been set here");
736 dirty_young_block(result, *actual_word_size);
737 } else {
738 *actual_word_size = 0;
739 }
740
741 return result;
742 }
743
744 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
745 assert(!is_init_completed(), "Expect to be called at JVM init time");
746 assert(ranges != NULL, "MemRegion array NULL");
747 assert(count != 0, "No MemRegions provided");
748 MemRegion reserved = _hrm->reserved();
749 HeapWord* prev_last_addr = NULL;
750 HeapRegion* prev_last_region = NULL;
751 size_t size_used = 0;
752 size_t uncommitted_regions = 0;
753
754 // For each Memregion, free the G1 regions that constitute it, and
755 // notify mark-sweep that the range is no longer to be considered 'archive.'
756 MutexLocker x(Heap_lock);
757 for (size_t i = 0; i < count; i++) {
758 HeapWord* start_address = ranges[i].start();
759 HeapWord* last_address = ranges[i].last();
760
761 assert(reserved.contains(start_address) && reserved.contains(last_address),
762 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
763 p2i(start_address), p2i(last_address));
764 assert(start_address > prev_last_addr,
765 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
766 p2i(start_address), p2i(prev_last_addr));
767 size_used += ranges[i].byte_size();
768 prev_last_addr = last_address;
769
770 HeapRegion* start_region = _hrm->addr_to_region(start_address);
771 HeapRegion* last_region = _hrm->addr_to_region(last_address);
772
773 // Check for ranges that start in the same G1 region in which the previous
774 // range ended, and adjust the start address so we don't try to free
775 // the same region again. If the current range is entirely within that
776 // region, skip it.
777 if (start_region == prev_last_region) {
778 start_address = start_region->end();
779 if (start_address > last_address) {
780 continue;
781 }
782 start_region = _hrm->addr_to_region(start_address);
783 }
784 prev_last_region = last_region;
785
786 // After verifying that each region was marked as an archive region by
787 // alloc_archive_regions, set it free and empty and uncommit it.
788 HeapRegion* curr_region = start_region;
789 while (curr_region != NULL) {
790 guarantee(curr_region->is_archive(),
791 "Expected archive region at index %u", curr_region->hrm_index());
792 uint curr_index = curr_region->hrm_index();
793 _archive_set.remove(curr_region);
794 curr_region->set_free();
795 curr_region->set_top(curr_region->bottom());
796 if (curr_region != last_region) {
797 curr_region = _hrm->next_region_in_heap(curr_region);
798 } else {
799 curr_region = NULL;
800 }
801 _hrm->shrink_at(curr_index, 1);
802 uncommitted_regions++;
803 }
804
805 // Notify mark-sweep that this is no longer an archive range.
806 G1ArchiveAllocator::clear_range_archive(ranges[i]);
807 }
808
809 if (uncommitted_regions != 0) {
810 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
811 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
812 }
813 decrease_used(size_used);
814 }
815
816 oop G1CollectedHeap::materialize_archived_object(oop obj) {
817 assert(obj != NULL, "archived obj is NULL");
818 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
819
820 // Loading an archived object makes it strongly reachable. If it is
821 // loaded during concurrent marking, it must be enqueued to the SATB
822 // queue, shading the previously white object gray.
823 G1BarrierSet::enqueue(obj);
824
825 return obj;
826 }
827
828 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
829 ResourceMark rm; // For retrieving the thread names in log messages.
830
831 // The structure of this method has a lot of similarities to
832 // attempt_allocation_slow(). The reason these two were not merged
833 // into a single one is that such a method would require several "if
834 // allocation is not humongous do this, otherwise do that"
835 // conditional paths which would obscure its flow. In fact, an early
836 // version of this code did use a unified method which was harder to
837 // follow and, as a result, it had subtle bugs that were hard to
838 // track down. So keeping these two methods separate allows each to
839 // be more readable. It will be good to keep these two in sync as
840 // much as possible.
841
842 assert_heap_not_locked_and_not_at_safepoint();
843 assert(is_humongous(word_size), "attempt_allocation_humongous() "
844 "should only be called for humongous allocations");
845
846 // Humongous objects can exhaust the heap quickly, so we should check if we
847 // need to start a marking cycle at each humongous object allocation. We do
848 // the check before we do the actual allocation. The reason for doing it
849 // before the allocation is that we avoid having to keep track of the newly
850 // allocated memory while we do a GC.
851 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
852 word_size)) {
853 collect(GCCause::_g1_humongous_allocation);
854 }
855
856 // We will loop until a) we manage to successfully perform the
857 // allocation or b) we successfully schedule a collection which
858 // fails to perform the allocation. b) is the only case when we'll
859 // return NULL.
860 HeapWord* result = NULL;
861 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
862 bool should_try_gc;
863 uint gc_count_before;
864
865
866 {
867 MutexLocker x(Heap_lock);
868
869 // Given that humongous objects are not allocated in young
870 // regions, we'll first try to do the allocation without doing a
871 // collection hoping that there's enough space in the heap.
872 result = humongous_obj_allocate(word_size);
873 if (result != NULL) {
874 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
875 policy()->old_gen_alloc_tracker()->
876 add_allocated_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
877 return result;
878 }
879
880 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
881 // the GCLocker initiated GC has been performed and then retry. This includes
882 // the case when the GC Locker is not active but has not been performed.
883 should_try_gc = !GCLocker::needs_gc();
884 // Read the GC count while still holding the Heap_lock.
885 gc_count_before = total_collections();
886 }
887
888 if (should_try_gc) {
889 bool succeeded;
890 result = do_collection_pause(word_size, gc_count_before, &succeeded,
891 GCCause::_g1_humongous_allocation);
892 if (result != NULL) {
893 assert(succeeded, "only way to get back a non-NULL result");
894 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
895 Thread::current()->name(), p2i(result));
896 return result;
897 }
898
899 if (succeeded) {
900 // We successfully scheduled a collection which failed to allocate. No
901 // point in trying to allocate further. We'll just return NULL.
902 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
903 SIZE_FORMAT " words", Thread::current()->name(), word_size);
904 return NULL;
905 }
906 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
907 Thread::current()->name(), word_size);
908 } else {
909 // Failed to schedule a collection.
910 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
911 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
912 SIZE_FORMAT " words", Thread::current()->name(), word_size);
913 return NULL;
914 }
915 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
916 // The GCLocker is either active or the GCLocker initiated
917 // GC has not yet been performed. Stall until it is and
918 // then retry the allocation.
919 GCLocker::stall_until_clear();
920 gclocker_retry_count += 1;
921 }
922
923
924 // We can reach here if we were unsuccessful in scheduling a
925 // collection (because another thread beat us to it) or if we were
926 // stalled due to the GC locker. In either can we should retry the
927 // allocation attempt in case another thread successfully
928 // performed a collection and reclaimed enough space.
929 // Humongous object allocation always needs a lock, so we wait for the retry
930 // in the next iteration of the loop, unlike for the regular iteration case.
931 // Give a warning if we seem to be looping forever.
932
933 if ((QueuedAllocationWarningCount > 0) &&
934 (try_count % QueuedAllocationWarningCount == 0)) {
935 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
936 Thread::current()->name(), try_count, word_size);
937 }
938 }
939
940 ShouldNotReachHere();
941 return NULL;
942 }
943
944 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
945 bool expect_null_mutator_alloc_region) {
946 assert_at_safepoint_on_vm_thread();
947 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
948 "the current alloc region was unexpectedly found to be non-NULL");
949
950 if (!is_humongous(word_size)) {
951 return _allocator->attempt_allocation_locked(word_size);
952 } else {
953 HeapWord* result = humongous_obj_allocate(word_size);
954 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
955 collector_state()->set_initiate_conc_mark_if_possible(true);
956 }
957 return result;
958 }
959
960 ShouldNotReachHere();
961 }
962
963 class PostCompactionPrinterClosure: public HeapRegionClosure {
964 private:
965 G1HRPrinter* _hr_printer;
966 public:
967 bool do_heap_region(HeapRegion* hr) {
968 assert(!hr->is_young(), "not expecting to find young regions");
969 _hr_printer->post_compaction(hr);
970 return false;
971 }
972
973 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
974 : _hr_printer(hr_printer) { }
975 };
976
977 void G1CollectedHeap::print_hrm_post_compaction() {
978 if (_hr_printer.is_active()) {
979 PostCompactionPrinterClosure cl(hr_printer());
980 heap_region_iterate(&cl);
981 }
982 }
983
984 void G1CollectedHeap::abort_concurrent_cycle() {
985 // If we start the compaction before the CM threads finish
986 // scanning the root regions we might trip them over as we'll
987 // be moving objects / updating references. So let's wait until
988 // they are done. By telling them to abort, they should complete
989 // early.
990 _cm->root_regions()->abort();
991 _cm->root_regions()->wait_until_scan_finished();
992
993 // Disable discovery and empty the discovered lists
994 // for the CM ref processor.
995 _ref_processor_cm->disable_discovery();
996 _ref_processor_cm->abandon_partial_discovery();
997 _ref_processor_cm->verify_no_references_recorded();
998
999 // Abandon current iterations of concurrent marking and concurrent
1000 // refinement, if any are in progress.
1001 concurrent_mark()->concurrent_cycle_abort();
1002 }
1003
1004 void G1CollectedHeap::prepare_heap_for_full_collection() {
1005 // Make sure we'll choose a new allocation region afterwards.
1006 _allocator->release_mutator_alloc_regions();
1007 _allocator->abandon_gc_alloc_regions();
1008
1009 // We may have added regions to the current incremental collection
1010 // set between the last GC or pause and now. We need to clear the
1011 // incremental collection set and then start rebuilding it afresh
1012 // after this full GC.
1013 abandon_collection_set(collection_set());
1014
1015 tear_down_region_sets(false /* free_list_only */);
1016
1017 hrm()->prepare_for_full_collection_start();
1018 }
1019
1020 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1021 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1022 assert_used_and_recalculate_used_equal(this);
1023 _verifier->verify_region_sets_optional();
1024 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1025 _verifier->check_bitmaps("Full GC Start");
1026 }
1027
1028 void G1CollectedHeap::prepare_heap_for_mutators() {
1029 hrm()->prepare_for_full_collection_end();
1030
1031 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1032 ClassLoaderDataGraph::purge();
1033 MetaspaceUtils::verify_metrics();
1034
1035 // Prepare heap for normal collections.
1036 assert(num_free_regions() == 0, "we should not have added any free regions");
1037 rebuild_region_sets(false /* free_list_only */);
1038 abort_refinement();
1039 resize_heap_if_necessary();
1040
1041 // Rebuild the strong code root lists for each region
1042 rebuild_strong_code_roots();
1043
1044 // Purge code root memory
1045 purge_code_root_memory();
1046
1047 // Start a new incremental collection set for the next pause
1048 start_new_collection_set();
1049
1050 _allocator->init_mutator_alloc_regions();
1051
1052 // Post collection state updates.
1053 MetaspaceGC::compute_new_size();
1054 }
1055
1056 void G1CollectedHeap::abort_refinement() {
1057 if (_hot_card_cache->use_cache()) {
1058 _hot_card_cache->reset_hot_cache();
1059 }
1060
1061 // Discard all remembered set updates and reset refinement statistics.
1062 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1063 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1064 "DCQS should be empty");
1065 concurrent_refine()->get_and_reset_refinement_stats();
1066 }
1067
1068 void G1CollectedHeap::verify_after_full_collection() {
1069 _hrm->verify_optional();
1070 _verifier->verify_region_sets_optional();
1071 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1072 // Clear the previous marking bitmap, if needed for bitmap verification.
1073 // Note we cannot do this when we clear the next marking bitmap in
1074 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1075 // objects marked during a full GC against the previous bitmap.
1076 // But we need to clear it before calling check_bitmaps below since
1077 // the full GC has compacted objects and updated TAMS but not updated
1078 // the prev bitmap.
1079 if (G1VerifyBitmaps) {
1080 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1081 _cm->clear_prev_bitmap(workers());
1082 }
1083 // This call implicitly verifies that the next bitmap is clear after Full GC.
1084 _verifier->check_bitmaps("Full GC End");
1085
1086 // At this point there should be no regions in the
1087 // entire heap tagged as young.
1088 assert(check_young_list_empty(), "young list should be empty at this point");
1089
1090 // Note: since we've just done a full GC, concurrent
1091 // marking is no longer active. Therefore we need not
1092 // re-enable reference discovery for the CM ref processor.
1093 // That will be done at the start of the next marking cycle.
1094 // We also know that the STW processor should no longer
1095 // discover any new references.
1096 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1097 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1098 _ref_processor_stw->verify_no_references_recorded();
1099 _ref_processor_cm->verify_no_references_recorded();
1100 }
1101
1102 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1103 // Post collection logging.
1104 // We should do this after we potentially resize the heap so
1105 // that all the COMMIT / UNCOMMIT events are generated before
1106 // the compaction events.
1107 print_hrm_post_compaction();
1108 heap_transition->print();
1109 print_heap_after_gc();
1110 print_heap_regions();
1111 }
1112
1113 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1114 bool clear_all_soft_refs) {
1115 assert_at_safepoint_on_vm_thread();
1116
1117 if (GCLocker::check_active_before_gc()) {
1118 // Full GC was not completed.
1119 return false;
1120 }
1121
1122 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1123 soft_ref_policy()->should_clear_all_soft_refs();
1124
1125 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1126 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1127
1128 collector.prepare_collection();
1129 collector.collect();
1130 collector.complete_collection();
1131
1132 // Full collection was successfully completed.
1133 return true;
1134 }
1135
1136 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1137 // Currently, there is no facility in the do_full_collection(bool) API to notify
1138 // the caller that the collection did not succeed (e.g., because it was locked
1139 // out by the GC locker). So, right now, we'll ignore the return value.
1140 bool dummy = do_full_collection(true, /* explicit_gc */
1141 clear_all_soft_refs);
1142 }
1143
1144 void G1CollectedHeap::resize_heap_if_necessary() {
1145 assert_at_safepoint_on_vm_thread();
1146
1147 bool should_expand;
1148 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1149
1150 if (resize_amount == 0) {
1151 return;
1152 } else if (should_expand) {
1153 expand(resize_amount, _workers);
1154 } else {
1155 shrink(resize_amount);
1156 }
1157 }
1158
1159 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1160 bool do_gc,
1161 bool clear_all_soft_refs,
1162 bool expect_null_mutator_alloc_region,
1163 bool* gc_succeeded) {
1164 *gc_succeeded = true;
1165 // Let's attempt the allocation first.
1166 HeapWord* result =
1167 attempt_allocation_at_safepoint(word_size,
1168 expect_null_mutator_alloc_region);
1169 if (result != NULL) {
1170 return result;
1171 }
1172
1173 // In a G1 heap, we're supposed to keep allocation from failing by
1174 // incremental pauses. Therefore, at least for now, we'll favor
1175 // expansion over collection. (This might change in the future if we can
1176 // do something smarter than full collection to satisfy a failed alloc.)
1177 result = expand_and_allocate(word_size);
1178 if (result != NULL) {
1179 return result;
1180 }
1181
1182 if (do_gc) {
1183 // Expansion didn't work, we'll try to do a Full GC.
1184 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1185 clear_all_soft_refs);
1186 }
1187
1188 return NULL;
1189 }
1190
1191 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1192 bool* succeeded) {
1193 assert_at_safepoint_on_vm_thread();
1194
1195 // Attempts to allocate followed by Full GC.
1196 HeapWord* result =
1197 satisfy_failed_allocation_helper(word_size,
1198 true, /* do_gc */
1199 false, /* clear_all_soft_refs */
1200 false, /* expect_null_mutator_alloc_region */
1201 succeeded);
1202
1203 if (result != NULL || !*succeeded) {
1204 return result;
1205 }
1206
1207 // Attempts to allocate followed by Full GC that will collect all soft references.
1208 result = satisfy_failed_allocation_helper(word_size,
1209 true, /* do_gc */
1210 true, /* clear_all_soft_refs */
1211 true, /* expect_null_mutator_alloc_region */
1212 succeeded);
1213
1214 if (result != NULL || !*succeeded) {
1215 return result;
1216 }
1217
1218 // Attempts to allocate, no GC
1219 result = satisfy_failed_allocation_helper(word_size,
1220 false, /* do_gc */
1221 false, /* clear_all_soft_refs */
1222 true, /* expect_null_mutator_alloc_region */
1223 succeeded);
1224
1225 if (result != NULL) {
1226 return result;
1227 }
1228
1229 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1230 "Flag should have been handled and cleared prior to this point");
1231
1232 // What else? We might try synchronous finalization later. If the total
1233 // space available is large enough for the allocation, then a more
1234 // complete compaction phase than we've tried so far might be
1235 // appropriate.
1236 return NULL;
1237 }
1238
1239 // Attempting to expand the heap sufficiently
1240 // to support an allocation of the given "word_size". If
1241 // successful, perform the allocation and return the address of the
1242 // allocated block, or else "NULL".
1243
1244 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1245 assert_at_safepoint_on_vm_thread();
1246
1247 _verifier->verify_region_sets_optional();
1248
1249 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1250 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1251 word_size * HeapWordSize);
1252
1253
1254 if (expand(expand_bytes, _workers)) {
1255 _hrm->verify_optional();
1256 _verifier->verify_region_sets_optional();
1257 return attempt_allocation_at_safepoint(word_size,
1258 false /* expect_null_mutator_alloc_region */);
1259 }
1260 return NULL;
1261 }
1262
1263 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1264 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1265 aligned_expand_bytes = align_up(aligned_expand_bytes,
1266 HeapRegion::GrainBytes);
1267
1268 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1269 expand_bytes, aligned_expand_bytes);
1270
1271 if (is_maximal_no_gc()) {
1272 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1273 return false;
1274 }
1275
1276 double expand_heap_start_time_sec = os::elapsedTime();
1277 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1278 assert(regions_to_expand > 0, "Must expand by at least one region");
1279
1280 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1281 if (expand_time_ms != NULL) {
1282 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1283 }
1284
1285 if (expanded_by > 0) {
1286 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1287 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1288 policy()->record_new_heap_size(num_regions());
1289 } else {
1290 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1291
1292 // The expansion of the virtual storage space was unsuccessful.
1293 // Let's see if it was because we ran out of swap.
1294 if (G1ExitOnExpansionFailure &&
1295 _hrm->available() >= regions_to_expand) {
1296 // We had head room...
1297 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1298 }
1299 }
1300 return regions_to_expand > 0;
1301 }
1302
1303 bool G1CollectedHeap::expand_single_region(uint node_index) {
1304 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1305
1306 if (expanded_by == 0) {
1307 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1308 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1309 return false;
1310 }
1311
1312 policy()->record_new_heap_size(num_regions());
1313 return true;
1314 }
1315
1316 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1317 size_t aligned_shrink_bytes =
1318 ReservedSpace::page_align_size_down(shrink_bytes);
1319 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1320 HeapRegion::GrainBytes);
1321 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1322
1323 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1324 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1325
1326 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",
1327 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1328 if (num_regions_removed > 0) {
1329 policy()->record_new_heap_size(num_regions());
1330 } else {
1331 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1332 }
1333 }
1334
1335 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1336 _verifier->verify_region_sets_optional();
1337
1338 // We should only reach here at the end of a Full GC or during Remark which
1339 // means we should not not be holding to any GC alloc regions. The method
1340 // below will make sure of that and do any remaining clean up.
1341 _allocator->abandon_gc_alloc_regions();
1342
1343 // Instead of tearing down / rebuilding the free lists here, we
1344 // could instead use the remove_all_pending() method on free_list to
1345 // remove only the ones that we need to remove.
1346 tear_down_region_sets(true /* free_list_only */);
1347 shrink_helper(shrink_bytes);
1348 rebuild_region_sets(true /* free_list_only */);
1349
1350 _hrm->verify_optional();
1351 _verifier->verify_region_sets_optional();
1352 }
1353
1354 class OldRegionSetChecker : public HeapRegionSetChecker {
1355 public:
1356 void check_mt_safety() {
1357 // Master Old Set MT safety protocol:
1358 // (a) If we're at a safepoint, operations on the master old set
1359 // should be invoked:
1360 // - by the VM thread (which will serialize them), or
1361 // - by the GC workers while holding the FreeList_lock, if we're
1362 // at a safepoint for an evacuation pause (this lock is taken
1363 // anyway when an GC alloc region is retired so that a new one
1364 // is allocated from the free list), or
1365 // - by the GC workers while holding the OldSets_lock, if we're at a
1366 // safepoint for a cleanup pause.
1367 // (b) If we're not at a safepoint, operations on the master old set
1368 // should be invoked while holding the Heap_lock.
1369
1370 if (SafepointSynchronize::is_at_safepoint()) {
1371 guarantee(Thread::current()->is_VM_thread() ||
1372 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1373 "master old set MT safety protocol at a safepoint");
1374 } else {
1375 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1376 }
1377 }
1378 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1379 const char* get_description() { return "Old Regions"; }
1380 };
1381
1382 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1383 public:
1384 void check_mt_safety() {
1385 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1386 "May only change archive regions during initialization or safepoint.");
1387 }
1388 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1389 const char* get_description() { return "Archive Regions"; }
1390 };
1391
1392 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1393 public:
1394 void check_mt_safety() {
1395 // Humongous Set MT safety protocol:
1396 // (a) If we're at a safepoint, operations on the master humongous
1397 // set should be invoked by either the VM thread (which will
1398 // serialize them) or by the GC workers while holding the
1399 // OldSets_lock.
1400 // (b) If we're not at a safepoint, operations on the master
1401 // humongous set should be invoked while holding the Heap_lock.
1402
1403 if (SafepointSynchronize::is_at_safepoint()) {
1404 guarantee(Thread::current()->is_VM_thread() ||
1405 OldSets_lock->owned_by_self(),
1406 "master humongous set MT safety protocol at a safepoint");
1407 } else {
1408 guarantee(Heap_lock->owned_by_self(),
1409 "master humongous set MT safety protocol outside a safepoint");
1410 }
1411 }
1412 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1413 const char* get_description() { return "Humongous Regions"; }
1414 };
1415
1416 G1CollectedHeap::G1CollectedHeap() :
1417 CollectedHeap(),
1418 _young_gen_sampling_thread(NULL),
1419 _workers(NULL),
1420 _card_table(NULL),
1421 _collection_pause_end(Ticks::now()),
1422 _soft_ref_policy(),
1423 _old_set("Old Region Set", new OldRegionSetChecker()),
1424 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1425 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1426 _bot(NULL),
1427 _listener(),
1428 _numa(G1NUMA::create()),
1429 _hrm(NULL),
1430 _allocator(NULL),
1431 _verifier(NULL),
1432 _summary_bytes_used(0),
1433 _bytes_used_during_gc(0),
1434 _archive_allocator(NULL),
1435 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1436 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1437 _expand_heap_after_alloc_failure(true),
1438 _g1mm(NULL),
1439 _humongous_reclaim_candidates(),
1440 _has_humongous_reclaim_candidates(false),
1441 _hr_printer(),
1442 _collector_state(),
1443 _old_marking_cycles_started(0),
1444 _old_marking_cycles_completed(0),
1445 _eden(),
1446 _survivor(),
1447 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1448 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1449 _policy(G1Policy::create_policy(_gc_timer_stw)),
1450 _heap_sizing_policy(NULL),
1451 _collection_set(this, _policy),
1452 _hot_card_cache(NULL),
1453 _rem_set(NULL),
1454 _cm(NULL),
1455 _cm_thread(NULL),
1456 _cr(NULL),
1457 _task_queues(NULL),
1458 _evacuation_failed(false),
1459 _evacuation_failed_info_array(NULL),
1460 _preserved_marks_set(true /* in_c_heap */),
1461 #ifndef PRODUCT
1462 _evacuation_failure_alot_for_current_gc(false),
1463 _evacuation_failure_alot_gc_number(0),
1464 _evacuation_failure_alot_count(0),
1465 #endif
1466 _ref_processor_stw(NULL),
1467 _is_alive_closure_stw(this),
1468 _is_subject_to_discovery_stw(this),
1469 _ref_processor_cm(NULL),
1470 _is_alive_closure_cm(this),
1471 _is_subject_to_discovery_cm(this),
1472 _region_attr() {
1473
1474 _verifier = new G1HeapVerifier(this);
1475
1476 _allocator = new G1Allocator(this);
1477
1478 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1479
1480 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1481
1482 // Override the default _filler_array_max_size so that no humongous filler
1483 // objects are created.
1484 _filler_array_max_size = _humongous_object_threshold_in_words;
1485
1486 uint n_queues = ParallelGCThreads;
1487 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1488
1489 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1490
1491 for (uint i = 0; i < n_queues; i++) {
1492 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1493 q->initialize();
1494 _task_queues->register_queue(i, q);
1495 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1496 }
1497
1498 // Initialize the G1EvacuationFailureALot counters and flags.
1499 NOT_PRODUCT(reset_evacuation_should_fail();)
1500 _gc_tracer_stw->initialize();
1501
1502 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1503 }
1504
1505 static size_t actual_reserved_page_size(ReservedSpace rs) {
1506 size_t page_size = os::vm_page_size();
1507 if (UseLargePages) {
1508 // There are two ways to manage large page memory.
1509 // 1. OS supports committing large page memory.
1510 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1511 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1512 // we reserved memory without large page.
1513 if (os::can_commit_large_page_memory() || rs.special()) {
1514 // An alignment at ReservedSpace comes from preferred page size or
1515 // heap alignment, and if the alignment came from heap alignment, it could be
1516 // larger than large pages size. So need to cap with the large page size.
1517 page_size = MIN2(rs.alignment(), os::large_page_size());
1518 }
1519 }
1520
1521 return page_size;
1522 }
1523
1524 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1525 size_t size,
1526 size_t translation_factor) {
1527 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1528 // Allocate a new reserved space, preferring to use large pages.
1529 ReservedSpace rs(size, preferred_page_size);
1530 size_t page_size = actual_reserved_page_size(rs);
1531 G1RegionToSpaceMapper* result =
1532 G1RegionToSpaceMapper::create_mapper(rs,
1533 size,
1534 page_size,
1535 HeapRegion::GrainBytes,
1536 translation_factor,
1537 mtGC);
1538
1539 os::trace_page_sizes_for_requested_size(description,
1540 size,
1541 preferred_page_size,
1542 page_size,
1543 rs.base(),
1544 rs.size());
1545
1546 return result;
1547 }
1548
1549 jint G1CollectedHeap::initialize_concurrent_refinement() {
1550 jint ecode = JNI_OK;
1551 _cr = G1ConcurrentRefine::create(&ecode);
1552 return ecode;
1553 }
1554
1555 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1556 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1557 if (_young_gen_sampling_thread->osthread() == NULL) {
1558 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1559 return JNI_ENOMEM;
1560 }
1561 return JNI_OK;
1562 }
1563
1564 jint G1CollectedHeap::initialize() {
1565
1566 // Necessary to satisfy locking discipline assertions.
1567
1568 MutexLocker x(Heap_lock);
1569
1570 // While there are no constraints in the GC code that HeapWordSize
1571 // be any particular value, there are multiple other areas in the
1572 // system which believe this to be true (e.g. oop->object_size in some
1573 // cases incorrectly returns the size in wordSize units rather than
1574 // HeapWordSize).
1575 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1576
1577 size_t init_byte_size = InitialHeapSize;
1578 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1579
1580 // Ensure that the sizes are properly aligned.
1581 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1582 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1583 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1584
1585 // Reserve the maximum.
1586
1587 // When compressed oops are enabled, the preferred heap base
1588 // is calculated by subtracting the requested size from the
1589 // 32Gb boundary and using the result as the base address for
1590 // heap reservation. If the requested size is not aligned to
1591 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1592 // into the ReservedHeapSpace constructor) then the actual
1593 // base of the reserved heap may end up differing from the
1594 // address that was requested (i.e. the preferred heap base).
1595 // If this happens then we could end up using a non-optimal
1596 // compressed oops mode.
1597
1598 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1599 HeapAlignment);
1600
1601 initialize_reserved_region(heap_rs);
1602
1603 // Create the barrier set for the entire reserved region.
1604 G1CardTable* ct = new G1CardTable(heap_rs.region());
1605 ct->initialize();
1606 G1BarrierSet* bs = new G1BarrierSet(ct);
1607 bs->initialize();
1608 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1609 BarrierSet::set_barrier_set(bs);
1610 _card_table = ct;
1611
1612 {
1613 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1614 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1615 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1616 }
1617
1618 // Create the hot card cache.
1619 _hot_card_cache = new G1HotCardCache(this);
1620
1621 // Carve out the G1 part of the heap.
1622 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1623 size_t page_size = actual_reserved_page_size(heap_rs);
1624 G1RegionToSpaceMapper* heap_storage =
1625 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1626 g1_rs.size(),
1627 page_size,
1628 HeapRegion::GrainBytes,
1629 1,
1630 mtJavaHeap);
1631 if(heap_storage == NULL) {
1632 vm_shutdown_during_initialization("Could not initialize G1 heap");
1633 return JNI_ERR;
1634 }
1635
1636 os::trace_page_sizes("Heap",
1637 MinHeapSize,
1638 reserved_byte_size,
1639 page_size,
1640 heap_rs.base(),
1641 heap_rs.size());
1642 heap_storage->set_mapping_changed_listener(&_listener);
1643
1644 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1645 G1RegionToSpaceMapper* bot_storage =
1646 create_aux_memory_mapper("Block Offset Table",
1647 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1648 G1BlockOffsetTable::heap_map_factor());
1649
1650 G1RegionToSpaceMapper* cardtable_storage =
1651 create_aux_memory_mapper("Card Table",
1652 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1653 G1CardTable::heap_map_factor());
1654
1655 G1RegionToSpaceMapper* card_counts_storage =
1656 create_aux_memory_mapper("Card Counts Table",
1657 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1658 G1CardCounts::heap_map_factor());
1659
1660 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1661 G1RegionToSpaceMapper* prev_bitmap_storage =
1662 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1663 G1RegionToSpaceMapper* next_bitmap_storage =
1664 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1665
1666 _hrm = HeapRegionManager::create_manager(this);
1667
1668 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1669 _card_table->initialize(cardtable_storage);
1670
1671 // Do later initialization work for concurrent refinement.
1672 _hot_card_cache->initialize(card_counts_storage);
1673
1674 // 6843694 - ensure that the maximum region index can fit
1675 // in the remembered set structures.
1676 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1677 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1678
1679 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1680 // start within the first card.
1681 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1682 // Also create a G1 rem set.
1683 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1684 _rem_set->initialize(max_reserved_capacity(), max_regions());
1685
1686 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1687 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1688 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1689 "too many cards per region");
1690
1691 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1692
1693 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1694
1695 {
1696 HeapWord* start = _hrm->reserved().start();
1697 HeapWord* end = _hrm->reserved().end();
1698 size_t granularity = HeapRegion::GrainBytes;
1699
1700 _region_attr.initialize(start, end, granularity);
1701 _humongous_reclaim_candidates.initialize(start, end, granularity);
1702 }
1703
1704 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1705 true /* are_GC_task_threads */,
1706 false /* are_ConcurrentGC_threads */);
1707 if (_workers == NULL) {
1708 return JNI_ENOMEM;
1709 }
1710 _workers->initialize_workers();
1711
1712 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1713
1714 // Create the G1ConcurrentMark data structure and thread.
1715 // (Must do this late, so that "max_regions" is defined.)
1716 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1717 _cm_thread = _cm->cm_thread();
1718
1719 // Now expand into the initial heap size.
1720 if (!expand(init_byte_size, _workers)) {
1721 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1722 return JNI_ENOMEM;
1723 }
1724
1725 // Perform any initialization actions delegated to the policy.
1726 policy()->init(this, &_collection_set);
1727
1728 jint ecode = initialize_concurrent_refinement();
1729 if (ecode != JNI_OK) {
1730 return ecode;
1731 }
1732
1733 ecode = initialize_young_gen_sampling_thread();
1734 if (ecode != JNI_OK) {
1735 return ecode;
1736 }
1737
1738 {
1739 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1740 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1741 dcqs.set_max_cards(concurrent_refine()->red_zone());
1742 }
1743
1744 // Here we allocate the dummy HeapRegion that is required by the
1745 // G1AllocRegion class.
1746 HeapRegion* dummy_region = _hrm->get_dummy_region();
1747
1748 // We'll re-use the same region whether the alloc region will
1749 // require BOT updates or not and, if it doesn't, then a non-young
1750 // region will complain that it cannot support allocations without
1751 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1752 dummy_region->set_eden();
1753 // Make sure it's full.
1754 dummy_region->set_top(dummy_region->end());
1755 G1AllocRegion::setup(this, dummy_region);
1756
1757 _allocator->init_mutator_alloc_regions();
1758
1759 // Do create of the monitoring and management support so that
1760 // values in the heap have been properly initialized.
1761 _g1mm = new G1MonitoringSupport(this);
1762
1763 G1StringDedup::initialize();
1764
1765 _preserved_marks_set.init(ParallelGCThreads);
1766
1767 _collection_set.initialize(max_regions());
1768
1769 G1InitLogger::print();
1770
1771 return JNI_OK;
1772 }
1773
1774 void G1CollectedHeap::stop() {
1775 // Stop all concurrent threads. We do this to make sure these threads
1776 // do not continue to execute and access resources (e.g. logging)
1777 // that are destroyed during shutdown.
1778 _cr->stop();
1779 _young_gen_sampling_thread->stop();
1780 _cm_thread->stop();
1781 if (G1StringDedup::is_enabled()) {
1782 G1StringDedup::stop();
1783 }
1784 }
1785
1786 void G1CollectedHeap::safepoint_synchronize_begin() {
1787 SuspendibleThreadSet::synchronize();
1788 }
1789
1790 void G1CollectedHeap::safepoint_synchronize_end() {
1791 SuspendibleThreadSet::desynchronize();
1792 }
1793
1794 void G1CollectedHeap::post_initialize() {
1795 CollectedHeap::post_initialize();
1796 ref_processing_init();
1797 }
1798
1799 void G1CollectedHeap::ref_processing_init() {
1800 // Reference processing in G1 currently works as follows:
1801 //
1802 // * There are two reference processor instances. One is
1803 // used to record and process discovered references
1804 // during concurrent marking; the other is used to
1805 // record and process references during STW pauses
1806 // (both full and incremental).
1807 // * Both ref processors need to 'span' the entire heap as
1808 // the regions in the collection set may be dotted around.
1809 //
1810 // * For the concurrent marking ref processor:
1811 // * Reference discovery is enabled at concurrent start.
1812 // * Reference discovery is disabled and the discovered
1813 // references processed etc during remarking.
1814 // * Reference discovery is MT (see below).
1815 // * Reference discovery requires a barrier (see below).
1816 // * Reference processing may or may not be MT
1817 // (depending on the value of ParallelRefProcEnabled
1818 // and ParallelGCThreads).
1819 // * A full GC disables reference discovery by the CM
1820 // ref processor and abandons any entries on it's
1821 // discovered lists.
1822 //
1823 // * For the STW processor:
1824 // * Non MT discovery is enabled at the start of a full GC.
1825 // * Processing and enqueueing during a full GC is non-MT.
1826 // * During a full GC, references are processed after marking.
1827 //
1828 // * Discovery (may or may not be MT) is enabled at the start
1829 // of an incremental evacuation pause.
1830 // * References are processed near the end of a STW evacuation pause.
1831 // * For both types of GC:
1832 // * Discovery is atomic - i.e. not concurrent.
1833 // * Reference discovery will not need a barrier.
1834
1835 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1836
1837 // Concurrent Mark ref processor
1838 _ref_processor_cm =
1839 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1840 mt_processing, // mt processing
1841 ParallelGCThreads, // degree of mt processing
1842 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1843 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1844 false, // Reference discovery is not atomic
1845 &_is_alive_closure_cm, // is alive closure
1846 true); // allow changes to number of processing threads
1847
1848 // STW ref processor
1849 _ref_processor_stw =
1850 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1851 mt_processing, // mt processing
1852 ParallelGCThreads, // degree of mt processing
1853 (ParallelGCThreads > 1), // mt discovery
1854 ParallelGCThreads, // degree of mt discovery
1855 true, // Reference discovery is atomic
1856 &_is_alive_closure_stw, // is alive closure
1857 true); // allow changes to number of processing threads
1858 }
1859
1860 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1861 return &_soft_ref_policy;
1862 }
1863
1864 size_t G1CollectedHeap::capacity() const {
1865 return _hrm->length() * HeapRegion::GrainBytes;
1866 }
1867
1868 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1869 return _hrm->total_free_bytes();
1870 }
1871
1872 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1873 _hot_card_cache->drain(cl, worker_id);
1874 }
1875
1876 // Computes the sum of the storage used by the various regions.
1877 size_t G1CollectedHeap::used() const {
1878 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1879 if (_archive_allocator != NULL) {
1880 result += _archive_allocator->used();
1881 }
1882 return result;
1883 }
1884
1885 size_t G1CollectedHeap::used_unlocked() const {
1886 return _summary_bytes_used;
1887 }
1888
1889 class SumUsedClosure: public HeapRegionClosure {
1890 size_t _used;
1891 public:
1892 SumUsedClosure() : _used(0) {}
1893 bool do_heap_region(HeapRegion* r) {
1894 _used += r->used();
1895 return false;
1896 }
1897 size_t result() { return _used; }
1898 };
1899
1900 size_t G1CollectedHeap::recalculate_used() const {
1901 SumUsedClosure blk;
1902 heap_region_iterate(&blk);
1903 return blk.result();
1904 }
1905
1906 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1907 switch (cause) {
1908 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1909 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1910 case GCCause::_wb_conc_mark: return true;
1911 default : return false;
1912 }
1913 }
1914
1915 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1916 switch (cause) {
1917 case GCCause::_g1_humongous_allocation: return true;
1918 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1919 case GCCause::_wb_breakpoint: return true;
1920 default: return is_user_requested_concurrent_full_gc(cause);
1921 }
1922 }
1923
1924 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1925 if (policy()->force_upgrade_to_full()) {
1926 return true;
1927 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1928 return false;
1929 } else if (has_regions_left_for_allocation()) {
1930 return false;
1931 } else {
1932 return true;
1933 }
1934 }
1935
1936 #ifndef PRODUCT
1937 void G1CollectedHeap::allocate_dummy_regions() {
1938 // Let's fill up most of the region
1939 size_t word_size = HeapRegion::GrainWords - 1024;
1940 // And as a result the region we'll allocate will be humongous.
1941 guarantee(is_humongous(word_size), "sanity");
1942
1943 // _filler_array_max_size is set to humongous object threshold
1944 // but temporarily change it to use CollectedHeap::fill_with_object().
1945 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1946
1947 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1948 // Let's use the existing mechanism for the allocation
1949 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1950 if (dummy_obj != NULL) {
1951 MemRegion mr(dummy_obj, word_size);
1952 CollectedHeap::fill_with_object(mr);
1953 } else {
1954 // If we can't allocate once, we probably cannot allocate
1955 // again. Let's get out of the loop.
1956 break;
1957 }
1958 }
1959 }
1960 #endif // !PRODUCT
1961
1962 void G1CollectedHeap::increment_old_marking_cycles_started() {
1963 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1964 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1965 "Wrong marking cycle count (started: %d, completed: %d)",
1966 _old_marking_cycles_started, _old_marking_cycles_completed);
1967
1968 _old_marking_cycles_started++;
1969 }
1970
1971 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1972 bool whole_heap_examined) {
1973 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1974
1975 // We assume that if concurrent == true, then the caller is a
1976 // concurrent thread that was joined the Suspendible Thread
1977 // Set. If there's ever a cheap way to check this, we should add an
1978 // assert here.
1979
1980 // Given that this method is called at the end of a Full GC or of a
1981 // concurrent cycle, and those can be nested (i.e., a Full GC can
1982 // interrupt a concurrent cycle), the number of full collections
1983 // completed should be either one (in the case where there was no
1984 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1985 // behind the number of full collections started.
1986
1987 // This is the case for the inner caller, i.e. a Full GC.
1988 assert(concurrent ||
1989 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1990 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1991 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1992 "is inconsistent with _old_marking_cycles_completed = %u",
1993 _old_marking_cycles_started, _old_marking_cycles_completed);
1994
1995 // This is the case for the outer caller, i.e. the concurrent cycle.
1996 assert(!concurrent ||
1997 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1998 "for outer caller (concurrent cycle): "
1999 "_old_marking_cycles_started = %u "
2000 "is inconsistent with _old_marking_cycles_completed = %u",
2001 _old_marking_cycles_started, _old_marking_cycles_completed);
2002
2003 _old_marking_cycles_completed += 1;
2004 if (whole_heap_examined) {
2005 // Signal that we have completed a visit to all live objects.
2006 record_whole_heap_examined_timestamp();
2007 }
2008
2009 // We need to clear the "in_progress" flag in the CM thread before
2010 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2011 // is set) so that if a waiter requests another System.gc() it doesn't
2012 // incorrectly see that a marking cycle is still in progress.
2013 if (concurrent) {
2014 _cm_thread->set_idle();
2015 }
2016
2017 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2018 // for a full GC to finish that their wait is over.
2019 ml.notify_all();
2020 }
2021
2022 void G1CollectedHeap::collect(GCCause::Cause cause) {
2023 try_collect(cause);
2024 }
2025
2026 // Return true if (x < y) with allowance for wraparound.
2027 static bool gc_counter_less_than(uint x, uint y) {
2028 return (x - y) > (UINT_MAX/2);
2029 }
2030
2031 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2032 // Macro so msg printing is format-checked.
2033 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2034 do { \
2035 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2036 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2037 ResourceMark rm; /* For thread name. */ \
2038 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2039 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2040 Thread::current()->name(), \
2041 GCCause::to_string(cause)); \
2042 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2043 } \
2044 } while (0)
2045
2046 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2047 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2048
2049 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2050 uint gc_counter,
2051 uint old_marking_started_before) {
2052 assert_heap_not_locked();
2053 assert(should_do_concurrent_full_gc(cause),
2054 "Non-concurrent cause %s", GCCause::to_string(cause));
2055
2056 for (uint i = 1; true; ++i) {
2057 // Try to schedule concurrent start evacuation pause that will
2058 // start a concurrent cycle.
2059 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2060 VM_G1TryInitiateConcMark op(gc_counter,
2061 cause,
2062 policy()->max_pause_time_ms());
2063 VMThread::execute(&op);
2064
2065 // Request is trivially finished.
2066 if (cause == GCCause::_g1_periodic_collection) {
2067 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2068 return op.gc_succeeded();
2069 }
2070
2071 // If VMOp skipped initiating concurrent marking cycle because
2072 // we're terminating, then we're done.
2073 if (op.terminating()) {
2074 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2075 return false;
2076 }
2077
2078 // Lock to get consistent set of values.
2079 uint old_marking_started_after;
2080 uint old_marking_completed_after;
2081 {
2082 MutexLocker ml(Heap_lock);
2083 // Update gc_counter for retrying VMOp if needed. Captured here to be
2084 // consistent with the values we use below for termination tests. If
2085 // a retry is needed after a possible wait, and another collection
2086 // occurs in the meantime, it will cause our retry to be skipped and
2087 // we'll recheck for termination with updated conditions from that
2088 // more recent collection. That's what we want, rather than having
2089 // our retry possibly perform an unnecessary collection.
2090 gc_counter = total_collections();
2091 old_marking_started_after = _old_marking_cycles_started;
2092 old_marking_completed_after = _old_marking_cycles_completed;
2093 }
2094
2095 if (cause == GCCause::_wb_breakpoint) {
2096 if (op.gc_succeeded()) {
2097 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2098 return true;
2099 }
2100 // When _wb_breakpoint there can't be another cycle or deferred.
2101 assert(!op.cycle_already_in_progress(), "invariant");
2102 assert(!op.whitebox_attached(), "invariant");
2103 // Concurrent cycle attempt might have been cancelled by some other
2104 // collection, so retry. Unlike other cases below, we want to retry
2105 // even if cancelled by a STW full collection, because we really want
2106 // to start a concurrent cycle.
2107 if (old_marking_started_before != old_marking_started_after) {
2108 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2109 old_marking_started_before = old_marking_started_after;
2110 }
2111 } else if (!GCCause::is_user_requested_gc(cause)) {
2112 // For an "automatic" (not user-requested) collection, we just need to
2113 // ensure that progress is made.
2114 //
2115 // Request is finished if any of
2116 // (1) the VMOp successfully performed a GC,
2117 // (2) a concurrent cycle was already in progress,
2118 // (3) whitebox is controlling concurrent cycles,
2119 // (4) a new cycle was started (by this thread or some other), or
2120 // (5) a Full GC was performed.
2121 // Cases (4) and (5) are detected together by a change to
2122 // _old_marking_cycles_started.
2123 //
2124 // Note that (1) does not imply (4). If we're still in the mixed
2125 // phase of an earlier concurrent collection, the request to make the
2126 // collection a concurrent start won't be honored. If we don't check for
2127 // both conditions we'll spin doing back-to-back collections.
2128 if (op.gc_succeeded() ||
2129 op.cycle_already_in_progress() ||
2130 op.whitebox_attached() ||
2131 (old_marking_started_before != old_marking_started_after)) {
2132 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2133 return true;
2134 }
2135 } else { // User-requested GC.
2136 // For a user-requested collection, we want to ensure that a complete
2137 // full collection has been performed before returning, but without
2138 // waiting for more than needed.
2139
2140 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2141 // new cycle was started. That's good, because it's not clear what we
2142 // should do otherwise. Trying again just does back to back GCs.
2143 // Can't wait for someone else to start a cycle. And returning fails
2144 // to meet the goal of ensuring a full collection was performed.
2145 assert(!op.gc_succeeded() ||
2146 (old_marking_started_before != old_marking_started_after),
2147 "invariant: succeeded %s, started before %u, started after %u",
2148 BOOL_TO_STR(op.gc_succeeded()),
2149 old_marking_started_before, old_marking_started_after);
2150
2151 // Request is finished if a full collection (concurrent or stw)
2152 // was started after this request and has completed, e.g.
2153 // started_before < completed_after.
2154 if (gc_counter_less_than(old_marking_started_before,
2155 old_marking_completed_after)) {
2156 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2157 return true;
2158 }
2159
2160 if (old_marking_started_after != old_marking_completed_after) {
2161 // If there is an in-progress cycle (possibly started by us), then
2162 // wait for that cycle to complete, e.g.
2163 // while completed_now < started_after.
2164 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2165 MonitorLocker ml(G1OldGCCount_lock);
2166 while (gc_counter_less_than(_old_marking_cycles_completed,
2167 old_marking_started_after)) {
2168 ml.wait();
2169 }
2170 // Request is finished if the collection we just waited for was
2171 // started after this request.
2172 if (old_marking_started_before != old_marking_started_after) {
2173 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2174 return true;
2175 }
2176 }
2177
2178 // If VMOp was successful then it started a new cycle that the above
2179 // wait &etc should have recognized as finishing this request. This
2180 // differs from a non-user-request, where gc_succeeded does not imply
2181 // a new cycle was started.
2182 assert(!op.gc_succeeded(), "invariant");
2183
2184 if (op.cycle_already_in_progress()) {
2185 // If VMOp failed because a cycle was already in progress, it
2186 // is now complete. But it didn't finish this user-requested
2187 // GC, so try again.
2188 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2189 continue;
2190 } else if (op.whitebox_attached()) {
2191 // If WhiteBox wants control, wait for notification of a state
2192 // change in the controller, then try again. Don't wait for
2193 // release of control, since collections may complete while in
2194 // control. Note: This won't recognize a STW full collection
2195 // while waiting; we can't wait on multiple monitors.
2196 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2197 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2198 if (ConcurrentGCBreakpoints::is_controlled()) {
2199 ml.wait();
2200 }
2201 continue;
2202 }
2203 }
2204
2205 // Collection failed and should be retried.
2206 assert(op.transient_failure(), "invariant");
2207
2208 if (GCLocker::is_active_and_needs_gc()) {
2209 // If GCLocker is active, wait until clear before retrying.
2210 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2211 GCLocker::stall_until_clear();
2212 }
2213
2214 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2215 }
2216 }
2217
2218 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2219 assert_heap_not_locked();
2220
2221 // Lock to get consistent set of values.
2222 uint gc_count_before;
2223 uint full_gc_count_before;
2224 uint old_marking_started_before;
2225 {
2226 MutexLocker ml(Heap_lock);
2227 gc_count_before = total_collections();
2228 full_gc_count_before = total_full_collections();
2229 old_marking_started_before = _old_marking_cycles_started;
2230 }
2231
2232 if (should_do_concurrent_full_gc(cause)) {
2233 return try_collect_concurrently(cause,
2234 gc_count_before,
2235 old_marking_started_before);
2236 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2237 // Indicate failure to be consistent with VMOp failure due to
2238 // another collection slipping in after our gc_count but before
2239 // our request is processed.
2240 return false;
2241 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2242 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2243
2244 // Schedule a standard evacuation pause. We're setting word_size
2245 // to 0 which means that we are not requesting a post-GC allocation.
2246 VM_G1CollectForAllocation op(0, /* word_size */
2247 gc_count_before,
2248 cause,
2249 policy()->max_pause_time_ms());
2250 VMThread::execute(&op);
2251 return op.gc_succeeded();
2252 } else {
2253 // Schedule a Full GC.
2254 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2255 VMThread::execute(&op);
2256 return op.gc_succeeded();
2257 }
2258 }
2259
2260 bool G1CollectedHeap::is_in(const void* p) const {
2261 if (_hrm->reserved().contains(p)) {
2262 // Given that we know that p is in the reserved space,
2263 // heap_region_containing() should successfully
2264 // return the containing region.
2265 HeapRegion* hr = heap_region_containing(p);
2266 return hr->is_in(p);
2267 } else {
2268 return false;
2269 }
2270 }
2271
2272 #ifdef ASSERT
2273 bool G1CollectedHeap::is_in_exact(const void* p) const {
2274 bool contains = reserved_region().contains(p);
2275 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2276 if (contains && available) {
2277 return true;
2278 } else {
2279 return false;
2280 }
2281 }
2282 #endif
2283
2284 // Iteration functions.
2285
2286 // Iterates an ObjectClosure over all objects within a HeapRegion.
2287
2288 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2289 ObjectClosure* _cl;
2290 public:
2291 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2292 bool do_heap_region(HeapRegion* r) {
2293 if (!r->is_continues_humongous()) {
2294 r->object_iterate(_cl);
2295 }
2296 return false;
2297 }
2298 };
2299
2300 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2301 IterateObjectClosureRegionClosure blk(cl);
2302 heap_region_iterate(&blk);
2303 }
2304
2305 class G1ParallelObjectIterator : public ParallelObjectIterator {
2306 private:
2307 G1CollectedHeap* _heap;
2308 HeapRegionClaimer _claimer;
2309
2310 public:
2311 G1ParallelObjectIterator(uint thread_num) :
2312 _heap(G1CollectedHeap::heap()),
2313 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2314
2315 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2316 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2317 }
2318 };
2319
2320 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2321 return new G1ParallelObjectIterator(thread_num);
2322 }
2323
2324 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2325 IterateObjectClosureRegionClosure blk(cl);
2326 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2327 }
2328
2329 void G1CollectedHeap::keep_alive(oop obj) {
2330 G1BarrierSet::enqueue(obj);
2331 }
2332
2333 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2334 _hrm->iterate(cl);
2335 }
2336
2337 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2338 HeapRegionClaimer *hrclaimer,
2339 uint worker_id) const {
2340 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2341 }
2342
2343 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2344 HeapRegionClaimer *hrclaimer) const {
2345 _hrm->par_iterate(cl, hrclaimer, 0);
2346 }
2347
2348 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2349 _collection_set.iterate(cl);
2350 }
2351
2352 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2353 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2354 }
2355
2356 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2357 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2358 }
2359
2360 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2361 HeapRegion* hr = heap_region_containing(addr);
2362 return hr->block_start(addr);
2363 }
2364
2365 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2366 HeapRegion* hr = heap_region_containing(addr);
2367 return hr->block_is_obj(addr);
2368 }
2369
2370 bool G1CollectedHeap::supports_tlab_allocation() const {
2371 return true;
2372 }
2373
2374 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2375 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2376 }
2377
2378 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2379 return _eden.length() * HeapRegion::GrainBytes;
2380 }
2381
2382 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2383 // must be equal to the humongous object limit.
2384 size_t G1CollectedHeap::max_tlab_size() const {
2385 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2386 }
2387
2388 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2389 return _allocator->unsafe_max_tlab_alloc();
2390 }
2391
2392 size_t G1CollectedHeap::max_capacity() const {
2393 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2394 }
2395
2396 size_t G1CollectedHeap::max_reserved_capacity() const {
2397 return _hrm->max_length() * HeapRegion::GrainBytes;
2398 }
2399
2400 void G1CollectedHeap::deduplicate_string(oop str) {
2401 assert(java_lang_String::is_instance(str), "invariant");
2402
2403 if (G1StringDedup::is_enabled()) {
2404 G1StringDedup::deduplicate(str);
2405 }
2406 }
2407
2408 void G1CollectedHeap::prepare_for_verify() {
2409 _verifier->prepare_for_verify();
2410 }
2411
2412 void G1CollectedHeap::verify(VerifyOption vo) {
2413 _verifier->verify(vo);
2414 }
2415
2416 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2417 return true;
2418 }
2419
2420 bool G1CollectedHeap::is_heterogeneous_heap() const {
2421 return G1Arguments::is_heterogeneous_heap();
2422 }
2423
2424 class PrintRegionClosure: public HeapRegionClosure {
2425 outputStream* _st;
2426 public:
2427 PrintRegionClosure(outputStream* st) : _st(st) {}
2428 bool do_heap_region(HeapRegion* r) {
2429 r->print_on(_st);
2430 return false;
2431 }
2432 };
2433
2434 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2435 const HeapRegion* hr,
2436 const VerifyOption vo) const {
2437 switch (vo) {
2438 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2439 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2440 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2441 default: ShouldNotReachHere();
2442 }
2443 return false; // keep some compilers happy
2444 }
2445
2446 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2447 const VerifyOption vo) const {
2448 switch (vo) {
2449 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2450 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2451 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2452 default: ShouldNotReachHere();
2453 }
2454 return false; // keep some compilers happy
2455 }
2456
2457 void G1CollectedHeap::print_heap_regions() const {
2458 LogTarget(Trace, gc, heap, region) lt;
2459 if (lt.is_enabled()) {
2460 LogStream ls(lt);
2461 print_regions_on(&ls);
2462 }
2463 }
2464
2465 void G1CollectedHeap::print_on(outputStream* st) const {
2466 st->print(" %-20s", "garbage-first heap");
2467 if (_hrm != NULL) {
2468 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2469 capacity()/K, used_unlocked()/K);
2470 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2471 p2i(_hrm->reserved().start()),
2472 p2i(_hrm->reserved().end()));
2473 }
2474 st->cr();
2475 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2476 uint young_regions = young_regions_count();
2477 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2478 (size_t) young_regions * HeapRegion::GrainBytes / K);
2479 uint survivor_regions = survivor_regions_count();
2480 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2481 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2482 st->cr();
2483 if (_numa->is_enabled()) {
2484 uint num_nodes = _numa->num_active_nodes();
2485 st->print(" remaining free region(s) on each NUMA node: ");
2486 const int* node_ids = _numa->node_ids();
2487 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2488 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2489 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2490 }
2491 st->cr();
2492 }
2493 MetaspaceUtils::print_on(st);
2494 }
2495
2496 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2497 if (_hrm == NULL) {
2498 return;
2499 }
2500
2501 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2502 "HS=humongous(starts), HC=humongous(continues), "
2503 "CS=collection set, F=free, "
2504 "OA=open archive, CA=closed archive, "
2505 "TAMS=top-at-mark-start (previous, next)");
2506 PrintRegionClosure blk(st);
2507 heap_region_iterate(&blk);
2508 }
2509
2510 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2511 print_on(st);
2512
2513 // Print the per-region information.
2514 if (_hrm != NULL) {
2515 st->cr();
2516 print_regions_on(st);
2517 }
2518 }
2519
2520 void G1CollectedHeap::print_on_error(outputStream* st) const {
2521 this->CollectedHeap::print_on_error(st);
2522
2523 if (_cm != NULL) {
2524 st->cr();
2525 _cm->print_on_error(st);
2526 }
2527 }
2528
2529 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2530 workers()->threads_do(tc);
2531 tc->do_thread(_cm_thread);
2532 _cm->threads_do(tc);
2533 _cr->threads_do(tc);
2534 tc->do_thread(_young_gen_sampling_thread);
2535 if (G1StringDedup::is_enabled()) {
2536 G1StringDedup::threads_do(tc);
2537 }
2538 }
2539
2540 void G1CollectedHeap::print_tracing_info() const {
2541 rem_set()->print_summary_info();
2542 concurrent_mark()->print_summary_info();
2543 }
2544
2545 #ifndef PRODUCT
2546 // Helpful for debugging RSet issues.
2547
2548 class PrintRSetsClosure : public HeapRegionClosure {
2549 private:
2550 const char* _msg;
2551 size_t _occupied_sum;
2552
2553 public:
2554 bool do_heap_region(HeapRegion* r) {
2555 HeapRegionRemSet* hrrs = r->rem_set();
2556 size_t occupied = hrrs->occupied();
2557 _occupied_sum += occupied;
2558
2559 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2560 if (occupied == 0) {
2561 tty->print_cr(" RSet is empty");
2562 } else {
2563 hrrs->print();
2564 }
2565 tty->print_cr("----------");
2566 return false;
2567 }
2568
2569 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2570 tty->cr();
2571 tty->print_cr("========================================");
2572 tty->print_cr("%s", msg);
2573 tty->cr();
2574 }
2575
2576 ~PrintRSetsClosure() {
2577 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2578 tty->print_cr("========================================");
2579 tty->cr();
2580 }
2581 };
2582
2583 void G1CollectedHeap::print_cset_rsets() {
2584 PrintRSetsClosure cl("Printing CSet RSets");
2585 collection_set_iterate_all(&cl);
2586 }
2587
2588 void G1CollectedHeap::print_all_rsets() {
2589 PrintRSetsClosure cl("Printing All RSets");;
2590 heap_region_iterate(&cl);
2591 }
2592 #endif // PRODUCT
2593
2594 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2595 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2596 }
2597
2598 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2599
2600 size_t eden_used_bytes = _eden.used_bytes();
2601 size_t survivor_used_bytes = _survivor.used_bytes();
2602 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2603
2604 size_t eden_capacity_bytes =
2605 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2606
2607 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2608 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2609 eden_capacity_bytes, survivor_used_bytes, num_regions());
2610 }
2611
2612 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2613 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2614 stats->unused(), stats->used(), stats->region_end_waste(),
2615 stats->regions_filled(), stats->direct_allocated(),
2616 stats->failure_used(), stats->failure_waste());
2617 }
2618
2619 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2620 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2621 gc_tracer->report_gc_heap_summary(when, heap_summary);
2622
2623 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2624 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2625 }
2626
2627 void G1CollectedHeap::gc_prologue(bool full) {
2628 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2629
2630 // This summary needs to be printed before incrementing total collections.
2631 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2632
2633 // Update common counters.
2634 increment_total_collections(full /* full gc */);
2635 if (full || collector_state()->in_concurrent_start_gc()) {
2636 increment_old_marking_cycles_started();
2637 }
2638
2639 // Fill TLAB's and such
2640 {
2641 Ticks start = Ticks::now();
2642 ensure_parsability(true);
2643 Tickspan dt = Ticks::now() - start;
2644 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2645 }
2646
2647 if (!full) {
2648 // Flush dirty card queues to qset, so later phases don't need to account
2649 // for partially filled per-thread queues and such. Not needed for full
2650 // collections, which ignore those logs.
2651 Ticks start = Ticks::now();
2652 G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2653 Tickspan dt = Ticks::now() - start;
2654 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2655 }
2656 }
2657
2658 void G1CollectedHeap::gc_epilogue(bool full) {
2659 // Update common counters.
2660 if (full) {
2661 // Update the number of full collections that have been completed.
2662 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2663 }
2664
2665 // We are at the end of the GC. Total collections has already been increased.
2666 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2667
2668 // FIXME: what is this about?
2669 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2670 // is set.
2671 #if COMPILER2_OR_JVMCI
2672 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2673 #endif
2674
2675 double start = os::elapsedTime();
2676 resize_all_tlabs();
2677 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2678
2679 MemoryService::track_memory_usage();
2680 // We have just completed a GC. Update the soft reference
2681 // policy with the new heap occupancy
2682 Universe::update_heap_info_at_gc();
2683
2684 // Print NUMA statistics.
2685 _numa->print_statistics();
2686
2687 _collection_pause_end = Ticks::now();
2688 }
2689
2690 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2691 LogTarget(Trace, gc, heap, verify) lt;
2692
2693 if (lt.is_enabled()) {
2694 LogStream ls(lt);
2695 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2696 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2697 heap_region_iterate(&cl);
2698 }
2699 }
2700
2701 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2702 uint gc_count_before,
2703 bool* succeeded,
2704 GCCause::Cause gc_cause) {
2705 assert_heap_not_locked_and_not_at_safepoint();
2706 VM_G1CollectForAllocation op(word_size,
2707 gc_count_before,
2708 gc_cause,
2709 policy()->max_pause_time_ms());
2710 VMThread::execute(&op);
2711
2712 HeapWord* result = op.result();
2713 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2714 assert(result == NULL || ret_succeeded,
2715 "the result should be NULL if the VM did not succeed");
2716 *succeeded = ret_succeeded;
2717
2718 assert_heap_not_locked();
2719 return result;
2720 }
2721
2722 void G1CollectedHeap::do_concurrent_mark() {
2723 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2724 if (!_cm_thread->in_progress()) {
2725 _cm_thread->set_started();
2726 CGC_lock->notify();
2727 }
2728 }
2729
2730 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2731 // We don't nominate objects with many remembered set entries, on
2732 // the assumption that such objects are likely still live.
2733 HeapRegionRemSet* rem_set = r->rem_set();
2734
2735 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2736 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2737 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2738 }
2739
2740 #ifndef PRODUCT
2741 void G1CollectedHeap::verify_region_attr_remset_update() {
2742 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2743 public:
2744 virtual bool do_heap_region(HeapRegion* r) {
2745 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2746 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2747 assert(r->rem_set()->is_tracked() == needs_remset_update,
2748 "Region %u remset tracking status (%s) different to region attribute (%s)",
2749 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2750 return false;
2751 }
2752 } cl;
2753 heap_region_iterate(&cl);
2754 }
2755 #endif
2756
2757 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2758 public:
2759 bool do_heap_region(HeapRegion* hr) {
2760 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2761 hr->verify_rem_set();
2762 }
2763 return false;
2764 }
2765 };
2766
2767 uint G1CollectedHeap::num_task_queues() const {
2768 return _task_queues->size();
2769 }
2770
2771 #if TASKQUEUE_STATS
2772 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2773 st->print_raw_cr("GC Task Stats");
2774 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2775 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2776 }
2777
2778 void G1CollectedHeap::print_taskqueue_stats() const {
2779 if (!log_is_enabled(Trace, gc, task, stats)) {
2780 return;
2781 }
2782 Log(gc, task, stats) log;
2783 ResourceMark rm;
2784 LogStream ls(log.trace());
2785 outputStream* st = &ls;
2786
2787 print_taskqueue_stats_hdr(st);
2788
2789 TaskQueueStats totals;
2790 const uint n = num_task_queues();
2791 for (uint i = 0; i < n; ++i) {
2792 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2793 totals += task_queue(i)->stats;
2794 }
2795 st->print_raw("tot "); totals.print(st); st->cr();
2796
2797 DEBUG_ONLY(totals.verify());
2798 }
2799
2800 void G1CollectedHeap::reset_taskqueue_stats() {
2801 const uint n = num_task_queues();
2802 for (uint i = 0; i < n; ++i) {
2803 task_queue(i)->stats.reset();
2804 }
2805 }
2806 #endif // TASKQUEUE_STATS
2807
2808 void G1CollectedHeap::wait_for_root_region_scanning() {
2809 double scan_wait_start = os::elapsedTime();
2810 // We have to wait until the CM threads finish scanning the
2811 // root regions as it's the only way to ensure that all the
2812 // objects on them have been correctly scanned before we start
2813 // moving them during the GC.
2814 bool waited = _cm->root_regions()->wait_until_scan_finished();
2815 double wait_time_ms = 0.0;
2816 if (waited) {
2817 double scan_wait_end = os::elapsedTime();
2818 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2819 }
2820 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2821 }
2822
2823 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2824 private:
2825 G1HRPrinter* _hr_printer;
2826 public:
2827 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2828
2829 virtual bool do_heap_region(HeapRegion* r) {
2830 _hr_printer->cset(r);
2831 return false;
2832 }
2833 };
2834
2835 void G1CollectedHeap::start_new_collection_set() {
2836 double start = os::elapsedTime();
2837
2838 collection_set()->start_incremental_building();
2839
2840 clear_region_attr();
2841
2842 guarantee(_eden.length() == 0, "eden should have been cleared");
2843 policy()->transfer_survivors_to_cset(survivor());
2844
2845 // We redo the verification but now wrt to the new CSet which
2846 // has just got initialized after the previous CSet was freed.
2847 _cm->verify_no_collection_set_oops();
2848
2849 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2850 }
2851
2852 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2853
2854 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2855 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2856 collection_set()->optional_region_length());
2857
2858 _cm->verify_no_collection_set_oops();
2859
2860 if (_hr_printer.is_active()) {
2861 G1PrintCollectionSetClosure cl(&_hr_printer);
2862 _collection_set.iterate(&cl);
2863 _collection_set.iterate_optional(&cl);
2864 }
2865 }
2866
2867 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2868 if (collector_state()->in_concurrent_start_gc()) {
2869 return G1HeapVerifier::G1VerifyConcurrentStart;
2870 } else if (collector_state()->in_young_only_phase()) {
2871 return G1HeapVerifier::G1VerifyYoungNormal;
2872 } else {
2873 return G1HeapVerifier::G1VerifyMixed;
2874 }
2875 }
2876
2877 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2878 if (VerifyRememberedSets) {
2879 log_info(gc, verify)("[Verifying RemSets before GC]");
2880 VerifyRegionRemSetClosure v_cl;
2881 heap_region_iterate(&v_cl);
2882 }
2883 _verifier->verify_before_gc(type);
2884 _verifier->check_bitmaps("GC Start");
2885 verify_numa_regions("GC Start");
2886 }
2887
2888 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2889 if (VerifyRememberedSets) {
2890 log_info(gc, verify)("[Verifying RemSets after GC]");
2891 VerifyRegionRemSetClosure v_cl;
2892 heap_region_iterate(&v_cl);
2893 }
2894 _verifier->verify_after_gc(type);
2895 _verifier->check_bitmaps("GC End");
2896 verify_numa_regions("GC End");
2897 }
2898
2899 void G1CollectedHeap::expand_heap_after_young_collection(){
2900 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2901 if (expand_bytes > 0) {
2902 // No need for an ergo logging here,
2903 // expansion_amount() does this when it returns a value > 0.
2904 double expand_ms;
2905 if (!expand(expand_bytes, _workers, &expand_ms)) {
2906 // We failed to expand the heap. Cannot do anything about it.
2907 }
2908 phase_times()->record_expand_heap_time(expand_ms);
2909 }
2910 }
2911
2912 const char* G1CollectedHeap::young_gc_name() const {
2913 if (collector_state()->in_concurrent_start_gc()) {
2914 return "Pause Young (Concurrent Start)";
2915 } else if (collector_state()->in_young_only_phase()) {
2916 if (collector_state()->in_young_gc_before_mixed()) {
2917 return "Pause Young (Prepare Mixed)";
2918 } else {
2919 return "Pause Young (Normal)";
2920 }
2921 } else {
2922 return "Pause Young (Mixed)";
2923 }
2924 }
2925
2926 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2927 assert_at_safepoint_on_vm_thread();
2928 guarantee(!is_gc_active(), "collection is not reentrant");
2929
2930 if (GCLocker::check_active_before_gc()) {
2931 return false;
2932 }
2933
2934 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2935 if (should_upgrade_to_full_gc(gc_cause())) {
2936 log_info(gc, ergo)("Attempting maximally compacting collection");
2937 bool result = do_full_collection(false /* explicit gc */,
2938 true /* clear_all_soft_refs */);
2939 // do_full_collection only fails if blocked by GC locker, but
2940 // we've already checked for that above.
2941 assert(result, "invariant");
2942 }
2943 return true;
2944 }
2945
2946 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2947 GCIdMark gc_id_mark;
2948
2949 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2950 ResourceMark rm;
2951
2952 policy()->note_gc_start();
2953
2954 _gc_timer_stw->register_gc_start();
2955 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2956
2957 wait_for_root_region_scanning();
2958
2959 print_heap_before_gc();
2960 print_heap_regions();
2961 trace_heap_before_gc(_gc_tracer_stw);
2962
2963 _verifier->verify_region_sets_optional();
2964 _verifier->verify_dirty_young_regions();
2965
2966 // We should not be doing concurrent start unless the concurrent mark thread is running
2967 if (!_cm_thread->should_terminate()) {
2968 // This call will decide whether this pause is a concurrent start
2969 // pause. If it is, in_concurrent_start_gc() will return true
2970 // for the duration of this pause.
2971 policy()->decide_on_conc_mark_initiation();
2972 }
2973
2974 // We do not allow concurrent start to be piggy-backed on a mixed GC.
2975 assert(!collector_state()->in_concurrent_start_gc() ||
2976 collector_state()->in_young_only_phase(), "sanity");
2977 // We also do not allow mixed GCs during marking.
2978 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2979
2980 // Record whether this pause is a concurrent start. When the current
2981 // thread has completed its logging output and it's safe to signal
2982 // the CM thread, the flag's value in the policy has been reset.
2983 bool should_start_conc_mark = collector_state()->in_concurrent_start_gc();
2984 if (should_start_conc_mark) {
2985 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2986 }
2987
2988 // Inner scope for scope based logging, timers, and stats collection
2989 {
2990 G1EvacuationInfo evacuation_info;
2991
2992 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2993
2994 GCTraceCPUTime tcpu;
2995
2996 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2997
2998 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2999 workers()->active_workers(),
3000 Threads::number_of_non_daemon_threads());
3001 active_workers = workers()->update_active_workers(active_workers);
3002 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3003
3004 G1MonitoringScope ms(g1mm(),
3005 false /* full_gc */,
3006 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3007
3008 G1HeapTransition heap_transition(this);
3009
3010 {
3011 IsGCActiveMark x;
3012
3013 gc_prologue(false);
3014
3015 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3016 verify_before_young_collection(verify_type);
3017
3018 {
3019 // The elapsed time induced by the start time below deliberately elides
3020 // the possible verification above.
3021 double sample_start_time_sec = os::elapsedTime();
3022
3023 // Please see comment in g1CollectedHeap.hpp and
3024 // G1CollectedHeap::ref_processing_init() to see how
3025 // reference processing currently works in G1.
3026 _ref_processor_stw->enable_discovery();
3027
3028 // We want to temporarily turn off discovery by the
3029 // CM ref processor, if necessary, and turn it back on
3030 // on again later if we do. Using a scoped
3031 // NoRefDiscovery object will do this.
3032 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3033
3034 policy()->record_collection_pause_start(sample_start_time_sec);
3035
3036 // Forget the current allocation region (we might even choose it to be part
3037 // of the collection set!).
3038 _allocator->release_mutator_alloc_regions();
3039
3040 calculate_collection_set(evacuation_info, target_pause_time_ms);
3041
3042 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3043 G1ParScanThreadStateSet per_thread_states(this,
3044 &rdcqs,
3045 workers()->active_workers(),
3046 collection_set()->young_region_length(),
3047 collection_set()->optional_region_length());
3048 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3049
3050 // Actually do the work...
3051 evacuate_initial_collection_set(&per_thread_states);
3052
3053 if (_collection_set.optional_region_length() != 0) {
3054 evacuate_optional_collection_set(&per_thread_states);
3055 }
3056 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3057
3058 start_new_collection_set();
3059
3060 _survivor_evac_stats.adjust_desired_plab_sz();
3061 _old_evac_stats.adjust_desired_plab_sz();
3062
3063 if (should_start_conc_mark) {
3064 // We have to do this before we notify the CM threads that
3065 // they can start working to make sure that all the
3066 // appropriate initialization is done on the CM object.
3067 concurrent_mark()->post_concurrent_start();
3068 // Note that we don't actually trigger the CM thread at
3069 // this point. We do that later when we're sure that
3070 // the current thread has completed its logging output.
3071 }
3072
3073 allocate_dummy_regions();
3074
3075 _allocator->init_mutator_alloc_regions();
3076
3077 expand_heap_after_young_collection();
3078
3079 double sample_end_time_sec = os::elapsedTime();
3080 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3081 policy()->record_collection_pause_end(pause_time_ms);
3082 }
3083
3084 verify_after_young_collection(verify_type);
3085
3086 gc_epilogue(false);
3087 }
3088
3089 // Print the remainder of the GC log output.
3090 if (evacuation_failed()) {
3091 log_info(gc)("To-space exhausted");
3092 }
3093
3094 policy()->print_phases();
3095 heap_transition.print();
3096
3097 _hrm->verify_optional();
3098 _verifier->verify_region_sets_optional();
3099
3100 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3101 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3102
3103 print_heap_after_gc();
3104 print_heap_regions();
3105 trace_heap_after_gc(_gc_tracer_stw);
3106
3107 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3108 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3109 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3110 // before any GC notifications are raised.
3111 g1mm()->update_sizes();
3112
3113 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3114 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3115 _gc_timer_stw->register_gc_end();
3116 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3117 }
3118 // It should now be safe to tell the concurrent mark thread to start
3119 // without its logging output interfering with the logging output
3120 // that came from the pause.
3121
3122 if (should_start_conc_mark) {
3123 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3124 // thread(s) could be running concurrently with us. Make sure that anything
3125 // after this point does not assume that we are the only GC thread running.
3126 // Note: of course, the actual marking work will not start until the safepoint
3127 // itself is released in SuspendibleThreadSet::desynchronize().
3128 do_concurrent_mark();
3129 ConcurrentGCBreakpoints::notify_idle_to_active();
3130 }
3131 }
3132
3133 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3134 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3135 workers()->run_task(&rsfp_task);
3136 }
3137
3138 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3139 double remove_self_forwards_start = os::elapsedTime();
3140
3141 remove_self_forwarding_pointers(rdcqs);
3142 _preserved_marks_set.restore(workers());
3143
3144 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3145 }
3146
3147 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3148 if (!_evacuation_failed) {
3149 _evacuation_failed = true;
3150 }
3151
3152 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3153 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3154 }
3155
3156 bool G1ParEvacuateFollowersClosure::offer_termination() {
3157 EventGCPhaseParallel event;
3158 G1ParScanThreadState* const pss = par_scan_state();
3159 start_term_time();
3160 const bool res = terminator()->offer_termination();
3161 end_term_time();
3162 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3163 return res;
3164 }
3165
3166 void G1ParEvacuateFollowersClosure::do_void() {
3167 EventGCPhaseParallel event;
3168 G1ParScanThreadState* const pss = par_scan_state();
3169 pss->trim_queue();
3170 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3171 do {
3172 EventGCPhaseParallel event;
3173 pss->steal_and_trim_queue(queues());
3174 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3175 } while (!offer_termination());
3176 }
3177
3178 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3179 bool class_unloading_occurred) {
3180 uint num_workers = workers()->active_workers();
3181 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3182 workers()->run_task(&unlink_task);
3183 }
3184
3185 // Clean string dedup data structures.
3186 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3187 // record the durations of the phases. Hence the almost-copy.
3188 class G1StringDedupCleaningTask : public AbstractGangTask {
3189 BoolObjectClosure* _is_alive;
3190 OopClosure* _keep_alive;
3191 G1GCPhaseTimes* _phase_times;
3192
3193 public:
3194 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3195 OopClosure* keep_alive,
3196 G1GCPhaseTimes* phase_times) :
3197 AbstractGangTask("Partial Cleaning Task"),
3198 _is_alive(is_alive),
3199 _keep_alive(keep_alive),
3200 _phase_times(phase_times)
3201 {
3202 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3203 StringDedup::gc_prologue(true);
3204 }
3205
3206 ~G1StringDedupCleaningTask() {
3207 StringDedup::gc_epilogue();
3208 }
3209
3210 void work(uint worker_id) {
3211 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3212 {
3213 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3214 StringDedupQueue::unlink_or_oops_do(&cl);
3215 }
3216 {
3217 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3218 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3219 }
3220 }
3221 };
3222
3223 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3224 OopClosure* keep_alive,
3225 G1GCPhaseTimes* phase_times) {
3226 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3227 workers()->run_task(&cl);
3228 }
3229
3230 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3231 private:
3232 G1RedirtyCardsQueueSet* _qset;
3233 G1CollectedHeap* _g1h;
3234 BufferNode* volatile _nodes;
3235
3236 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3237 size_t buffer_size = _qset->buffer_size();
3238 BufferNode* next = Atomic::load(&_nodes);
3239 while (next != NULL) {
3240 BufferNode* node = next;
3241 next = Atomic::cmpxchg(&_nodes, node, node->next());
3242 if (next == node) {
3243 cl->apply_to_buffer(node, buffer_size, worker_id);
3244 next = node->next();
3245 }
3246 }
3247 }
3248
3249 public:
3250 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3251 AbstractGangTask("Redirty Cards"),
3252 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3253
3254 virtual void work(uint worker_id) {
3255 G1GCPhaseTimes* p = _g1h->phase_times();
3256 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3257
3258 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3259 par_apply(&cl, worker_id);
3260
3261 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3262 }
3263 };
3264
3265 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3266 double redirty_logged_cards_start = os::elapsedTime();
3267
3268 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3269 workers()->run_task(&redirty_task);
3270
3271 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3272 dcq.merge_bufferlists(rdcqs);
3273
3274 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3275 }
3276
3277 // Weak Reference Processing support
3278
3279 bool G1STWIsAliveClosure::do_object_b(oop p) {
3280 // An object is reachable if it is outside the collection set,
3281 // or is inside and copied.
3282 return !_g1h->is_in_cset(p) || p->is_forwarded();
3283 }
3284
3285 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3286 assert(obj != NULL, "must not be NULL");
3287 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3288 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3289 // may falsely indicate that this is not the case here: however the collection set only
3290 // contains old regions when concurrent mark is not running.
3291 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3292 }
3293
3294 // Non Copying Keep Alive closure
3295 class G1KeepAliveClosure: public OopClosure {
3296 G1CollectedHeap*_g1h;
3297 public:
3298 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3299 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3300 void do_oop(oop* p) {
3301 oop obj = *p;
3302 assert(obj != NULL, "the caller should have filtered out NULL values");
3303
3304 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3305 if (!region_attr.is_in_cset_or_humongous()) {
3306 return;
3307 }
3308 if (region_attr.is_in_cset()) {
3309 assert( obj->is_forwarded(), "invariant" );
3310 *p = obj->forwardee();
3311 } else {
3312 assert(!obj->is_forwarded(), "invariant" );
3313 assert(region_attr.is_humongous(),
3314 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3315 _g1h->set_humongous_is_live(obj);
3316 }
3317 }
3318 };
3319
3320 // Copying Keep Alive closure - can be called from both
3321 // serial and parallel code as long as different worker
3322 // threads utilize different G1ParScanThreadState instances
3323 // and different queues.
3324
3325 class G1CopyingKeepAliveClosure: public OopClosure {
3326 G1CollectedHeap* _g1h;
3327 G1ParScanThreadState* _par_scan_state;
3328
3329 public:
3330 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3331 G1ParScanThreadState* pss):
3332 _g1h(g1h),
3333 _par_scan_state(pss)
3334 {}
3335
3336 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3337 virtual void do_oop( oop* p) { do_oop_work(p); }
3338
3339 template <class T> void do_oop_work(T* p) {
3340 oop obj = RawAccess<>::oop_load(p);
3341
3342 if (_g1h->is_in_cset_or_humongous(obj)) {
3343 // If the referent object has been forwarded (either copied
3344 // to a new location or to itself in the event of an
3345 // evacuation failure) then we need to update the reference
3346 // field and, if both reference and referent are in the G1
3347 // heap, update the RSet for the referent.
3348 //
3349 // If the referent has not been forwarded then we have to keep
3350 // it alive by policy. Therefore we have copy the referent.
3351 //
3352 // When the queue is drained (after each phase of reference processing)
3353 // the object and it's followers will be copied, the reference field set
3354 // to point to the new location, and the RSet updated.
3355 _par_scan_state->push_on_queue(ScannerTask(p));
3356 }
3357 }
3358 };
3359
3360 // Serial drain queue closure. Called as the 'complete_gc'
3361 // closure for each discovered list in some of the
3362 // reference processing phases.
3363
3364 class G1STWDrainQueueClosure: public VoidClosure {
3365 protected:
3366 G1CollectedHeap* _g1h;
3367 G1ParScanThreadState* _par_scan_state;
3368
3369 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3370
3371 public:
3372 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3373 _g1h(g1h),
3374 _par_scan_state(pss)
3375 { }
3376
3377 void do_void() {
3378 G1ParScanThreadState* const pss = par_scan_state();
3379 pss->trim_queue();
3380 }
3381 };
3382
3383 // Parallel Reference Processing closures
3384
3385 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3386 // processing during G1 evacuation pauses.
3387
3388 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3389 private:
3390 G1CollectedHeap* _g1h;
3391 G1ParScanThreadStateSet* _pss;
3392 G1ScannerTasksQueueSet* _queues;
3393 WorkGang* _workers;
3394
3395 public:
3396 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3397 G1ParScanThreadStateSet* per_thread_states,
3398 WorkGang* workers,
3399 G1ScannerTasksQueueSet *task_queues) :
3400 _g1h(g1h),
3401 _pss(per_thread_states),
3402 _queues(task_queues),
3403 _workers(workers)
3404 {
3405 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3406 }
3407
3408 // Executes the given task using concurrent marking worker threads.
3409 virtual void execute(ProcessTask& task, uint ergo_workers);
3410 };
3411
3412 // Gang task for possibly parallel reference processing
3413
3414 class G1STWRefProcTaskProxy: public AbstractGangTask {
3415 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3416 ProcessTask& _proc_task;
3417 G1CollectedHeap* _g1h;
3418 G1ParScanThreadStateSet* _pss;
3419 G1ScannerTasksQueueSet* _task_queues;
3420 TaskTerminator* _terminator;
3421
3422 public:
3423 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3424 G1CollectedHeap* g1h,
3425 G1ParScanThreadStateSet* per_thread_states,
3426 G1ScannerTasksQueueSet *task_queues,
3427 TaskTerminator* terminator) :
3428 AbstractGangTask("Process reference objects in parallel"),
3429 _proc_task(proc_task),
3430 _g1h(g1h),
3431 _pss(per_thread_states),
3432 _task_queues(task_queues),
3433 _terminator(terminator)
3434 {}
3435
3436 virtual void work(uint worker_id) {
3437 // The reference processing task executed by a single worker.
3438 ResourceMark rm;
3439
3440 G1STWIsAliveClosure is_alive(_g1h);
3441
3442 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3443 pss->set_ref_discoverer(NULL);
3444
3445 // Keep alive closure.
3446 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3447
3448 // Complete GC closure
3449 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3450
3451 // Call the reference processing task's work routine.
3452 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3453
3454 // Note we cannot assert that the refs array is empty here as not all
3455 // of the processing tasks (specifically phase2 - pp2_work) execute
3456 // the complete_gc closure (which ordinarily would drain the queue) so
3457 // the queue may not be empty.
3458 }
3459 };
3460
3461 // Driver routine for parallel reference processing.
3462 // Creates an instance of the ref processing gang
3463 // task and has the worker threads execute it.
3464 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3465 assert(_workers != NULL, "Need parallel worker threads.");
3466
3467 assert(_workers->active_workers() >= ergo_workers,
3468 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3469 ergo_workers, _workers->active_workers());
3470 TaskTerminator terminator(ergo_workers, _queues);
3471 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3472
3473 _workers->run_task(&proc_task_proxy, ergo_workers);
3474 }
3475
3476 // End of weak reference support closures
3477
3478 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3479 double ref_proc_start = os::elapsedTime();
3480
3481 ReferenceProcessor* rp = _ref_processor_stw;
3482 assert(rp->discovery_enabled(), "should have been enabled");
3483
3484 // Closure to test whether a referent is alive.
3485 G1STWIsAliveClosure is_alive(this);
3486
3487 // Even when parallel reference processing is enabled, the processing
3488 // of JNI refs is serial and performed serially by the current thread
3489 // rather than by a worker. The following PSS will be used for processing
3490 // JNI refs.
3491
3492 // Use only a single queue for this PSS.
3493 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3494 pss->set_ref_discoverer(NULL);
3495 assert(pss->queue_is_empty(), "pre-condition");
3496
3497 // Keep alive closure.
3498 G1CopyingKeepAliveClosure keep_alive(this, pss);
3499
3500 // Serial Complete GC closure
3501 G1STWDrainQueueClosure drain_queue(this, pss);
3502
3503 // Setup the soft refs policy...
3504 rp->setup_policy(false);
3505
3506 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3507
3508 ReferenceProcessorStats stats;
3509 if (!rp->processing_is_mt()) {
3510 // Serial reference processing...
3511 stats = rp->process_discovered_references(&is_alive,
3512 &keep_alive,
3513 &drain_queue,
3514 NULL,
3515 pt);
3516 } else {
3517 uint no_of_gc_workers = workers()->active_workers();
3518
3519 // Parallel reference processing
3520 assert(no_of_gc_workers <= rp->max_num_queues(),
3521 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3522 no_of_gc_workers, rp->max_num_queues());
3523
3524 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3525 stats = rp->process_discovered_references(&is_alive,
3526 &keep_alive,
3527 &drain_queue,
3528 &par_task_executor,
3529 pt);
3530 }
3531
3532 _gc_tracer_stw->report_gc_reference_stats(stats);
3533
3534 // We have completed copying any necessary live referent objects.
3535 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3536
3537 make_pending_list_reachable();
3538
3539 assert(!rp->discovery_enabled(), "Postcondition");
3540 rp->verify_no_references_recorded();
3541
3542 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3543 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3544 }
3545
3546 void G1CollectedHeap::make_pending_list_reachable() {
3547 if (collector_state()->in_concurrent_start_gc()) {
3548 oop pll_head = Universe::reference_pending_list();
3549 if (pll_head != NULL) {
3550 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3551 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3552 }
3553 }
3554 }
3555
3556 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3557 Ticks start = Ticks::now();
3558 per_thread_states->flush();
3559 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3560 }
3561
3562 class G1PrepareEvacuationTask : public AbstractGangTask {
3563 class G1PrepareRegionsClosure : public HeapRegionClosure {
3564 G1CollectedHeap* _g1h;
3565 G1PrepareEvacuationTask* _parent_task;
3566 size_t _worker_humongous_total;
3567 size_t _worker_humongous_candidates;
3568
3569 bool humongous_region_is_candidate(HeapRegion* region) const {
3570 assert(region->is_starts_humongous(), "Must start a humongous object");
3571
3572 oop obj = oop(region->bottom());
3573
3574 // Dead objects cannot be eager reclaim candidates. Due to class
3575 // unloading it is unsafe to query their classes so we return early.
3576 if (_g1h->is_obj_dead(obj, region)) {
3577 return false;
3578 }
3579
3580 // If we do not have a complete remembered set for the region, then we can
3581 // not be sure that we have all references to it.
3582 if (!region->rem_set()->is_complete()) {
3583 return false;
3584 }
3585 // Candidate selection must satisfy the following constraints
3586 // while concurrent marking is in progress:
3587 //
3588 // * In order to maintain SATB invariants, an object must not be
3589 // reclaimed if it was allocated before the start of marking and
3590 // has not had its references scanned. Such an object must have
3591 // its references (including type metadata) scanned to ensure no
3592 // live objects are missed by the marking process. Objects
3593 // allocated after the start of concurrent marking don't need to
3594 // be scanned.
3595 //
3596 // * An object must not be reclaimed if it is on the concurrent
3597 // mark stack. Objects allocated after the start of concurrent
3598 // marking are never pushed on the mark stack.
3599 //
3600 // Nominating only objects allocated after the start of concurrent
3601 // marking is sufficient to meet both constraints. This may miss
3602 // some objects that satisfy the constraints, but the marking data
3603 // structures don't support efficiently performing the needed
3604 // additional tests or scrubbing of the mark stack.
3605 //
3606 // However, we presently only nominate is_typeArray() objects.
3607 // A humongous object containing references induces remembered
3608 // set entries on other regions. In order to reclaim such an
3609 // object, those remembered sets would need to be cleaned up.
3610 //
3611 // We also treat is_typeArray() objects specially, allowing them
3612 // to be reclaimed even if allocated before the start of
3613 // concurrent mark. For this we rely on mark stack insertion to
3614 // exclude is_typeArray() objects, preventing reclaiming an object
3615 // that is in the mark stack. We also rely on the metadata for
3616 // such objects to be built-in and so ensured to be kept live.
3617 // Frequent allocation and drop of large binary blobs is an
3618 // important use case for eager reclaim, and this special handling
3619 // may reduce needed headroom.
3620
3621 return obj->is_typeArray() &&
3622 _g1h->is_potential_eager_reclaim_candidate(region);
3623 }
3624
3625 public:
3626 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3627 _g1h(g1h),
3628 _parent_task(parent_task),
3629 _worker_humongous_total(0),
3630 _worker_humongous_candidates(0) { }
3631
3632 ~G1PrepareRegionsClosure() {
3633 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3634 _parent_task->add_humongous_total(_worker_humongous_total);
3635 }
3636
3637 virtual bool do_heap_region(HeapRegion* hr) {
3638 // First prepare the region for scanning
3639 _g1h->rem_set()->prepare_region_for_scan(hr);
3640
3641 // Now check if region is a humongous candidate
3642 if (!hr->is_starts_humongous()) {
3643 _g1h->register_region_with_region_attr(hr);
3644 return false;
3645 }
3646
3647 uint index = hr->hrm_index();
3648 if (humongous_region_is_candidate(hr)) {
3649 _g1h->set_humongous_reclaim_candidate(index, true);
3650 _g1h->register_humongous_region_with_region_attr(index);
3651 _worker_humongous_candidates++;
3652 // We will later handle the remembered sets of these regions.
3653 } else {
3654 _g1h->set_humongous_reclaim_candidate(index, false);
3655 _g1h->register_region_with_region_attr(hr);
3656 }
3657 _worker_humongous_total++;
3658
3659 return false;
3660 }
3661 };
3662
3663 G1CollectedHeap* _g1h;
3664 HeapRegionClaimer _claimer;
3665 volatile size_t _humongous_total;
3666 volatile size_t _humongous_candidates;
3667 public:
3668 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3669 AbstractGangTask("Prepare Evacuation"),
3670 _g1h(g1h),
3671 _claimer(_g1h->workers()->active_workers()),
3672 _humongous_total(0),
3673 _humongous_candidates(0) { }
3674
3675 ~G1PrepareEvacuationTask() {
3676 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3677 }
3678
3679 void work(uint worker_id) {
3680 G1PrepareRegionsClosure cl(_g1h, this);
3681 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3682 }
3683
3684 void add_humongous_candidates(size_t candidates) {
3685 Atomic::add(&_humongous_candidates, candidates);
3686 }
3687
3688 void add_humongous_total(size_t total) {
3689 Atomic::add(&_humongous_total, total);
3690 }
3691
3692 size_t humongous_candidates() {
3693 return _humongous_candidates;
3694 }
3695
3696 size_t humongous_total() {
3697 return _humongous_total;
3698 }
3699 };
3700
3701 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3702 _bytes_used_during_gc = 0;
3703
3704 _expand_heap_after_alloc_failure = true;
3705 _evacuation_failed = false;
3706
3707 // Disable the hot card cache.
3708 _hot_card_cache->reset_hot_cache_claimed_index();
3709 _hot_card_cache->set_use_cache(false);
3710
3711 // Initialize the GC alloc regions.
3712 _allocator->init_gc_alloc_regions(evacuation_info);
3713
3714 {
3715 Ticks start = Ticks::now();
3716 rem_set()->prepare_for_scan_heap_roots();
3717 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3718 }
3719
3720 {
3721 G1PrepareEvacuationTask g1_prep_task(this);
3722 Tickspan task_time = run_task_timed(&g1_prep_task);
3723
3724 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3725 g1_prep_task.humongous_total(),
3726 g1_prep_task.humongous_candidates());
3727 }
3728
3729 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3730 _preserved_marks_set.assert_empty();
3731
3732 #if COMPILER2_OR_JVMCI
3733 DerivedPointerTable::clear();
3734 #endif
3735
3736 // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3737 if (collector_state()->in_concurrent_start_gc()) {
3738 concurrent_mark()->pre_concurrent_start();
3739
3740 double start_clear_claimed_marks = os::elapsedTime();
3741
3742 ClassLoaderDataGraph::clear_claimed_marks();
3743
3744 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3745 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3746 }
3747
3748 // Should G1EvacuationFailureALot be in effect for this GC?
3749 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3750 }
3751
3752 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3753 protected:
3754 G1CollectedHeap* _g1h;
3755 G1ParScanThreadStateSet* _per_thread_states;
3756 G1ScannerTasksQueueSet* _task_queues;
3757 TaskTerminator _terminator;
3758 uint _num_workers;
3759
3760 void evacuate_live_objects(G1ParScanThreadState* pss,
3761 uint worker_id,
3762 G1GCPhaseTimes::GCParPhases objcopy_phase,
3763 G1GCPhaseTimes::GCParPhases termination_phase) {
3764 G1GCPhaseTimes* p = _g1h->phase_times();
3765
3766 Ticks start = Ticks::now();
3767 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3768 cl.do_void();
3769
3770 assert(pss->queue_is_empty(), "should be empty");
3771
3772 Tickspan evac_time = (Ticks::now() - start);
3773 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3774
3775 if (termination_phase == G1GCPhaseTimes::Termination) {
3776 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3777 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3778 } else {
3779 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3780 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3781 }
3782 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3783 }
3784
3785 virtual void start_work(uint worker_id) { }
3786
3787 virtual void end_work(uint worker_id) { }
3788
3789 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3790
3791 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3792
3793 public:
3794 G1EvacuateRegionsBaseTask(const char* name,
3795 G1ParScanThreadStateSet* per_thread_states,
3796 G1ScannerTasksQueueSet* task_queues,
3797 uint num_workers) :
3798 AbstractGangTask(name),
3799 _g1h(G1CollectedHeap::heap()),
3800 _per_thread_states(per_thread_states),
3801 _task_queues(task_queues),
3802 _terminator(num_workers, _task_queues),
3803 _num_workers(num_workers)
3804 { }
3805
3806 void work(uint worker_id) {
3807 start_work(worker_id);
3808
3809 {
3810 ResourceMark rm;
3811
3812 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3813 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3814
3815 scan_roots(pss, worker_id);
3816 evacuate_live_objects(pss, worker_id);
3817 }
3818
3819 end_work(worker_id);
3820 }
3821 };
3822
3823 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3824 G1RootProcessor* _root_processor;
3825
3826 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3827 _root_processor->evacuate_roots(pss, worker_id);
3828 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3829 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3830 }
3831
3832 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3833 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3834 }
3835
3836 void start_work(uint worker_id) {
3837 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3838 }
3839
3840 void end_work(uint worker_id) {
3841 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3842 }
3843
3844 public:
3845 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3846 G1ParScanThreadStateSet* per_thread_states,
3847 G1ScannerTasksQueueSet* task_queues,
3848 G1RootProcessor* root_processor,
3849 uint num_workers) :
3850 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3851 _root_processor(root_processor)
3852 { }
3853 };
3854
3855 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3856 G1GCPhaseTimes* p = phase_times();
3857
3858 {
3859 Ticks start = Ticks::now();
3860 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3861 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3862 }
3863
3864 Tickspan task_time;
3865 const uint num_workers = workers()->active_workers();
3866
3867 Ticks start_processing = Ticks::now();
3868 {
3869 G1RootProcessor root_processor(this, num_workers);
3870 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3871 task_time = run_task_timed(&g1_par_task);
3872 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3873 // To extract its code root fixup time we measure total time of this scope and
3874 // subtract from the time the WorkGang task took.
3875 }
3876 Tickspan total_processing = Ticks::now() - start_processing;
3877
3878 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3879 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3880 }
3881
3882 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3883
3884 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3885 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3886 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3887 }
3888
3889 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3890 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3891 }
3892
3893 public:
3894 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3895 G1ScannerTasksQueueSet* queues,
3896 uint num_workers) :
3897 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3898 }
3899 };
3900
3901 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3902 class G1MarkScope : public MarkScope { };
3903
3904 Tickspan task_time;
3905
3906 Ticks start_processing = Ticks::now();
3907 {
3908 G1MarkScope code_mark_scope;
3909 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3910 task_time = run_task_timed(&task);
3911 // See comment in evacuate_collection_set() for the reason of the scope.
3912 }
3913 Tickspan total_processing = Ticks::now() - start_processing;
3914
3915 G1GCPhaseTimes* p = phase_times();
3916 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3917 }
3918
3919 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3920 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3921
3922 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3923
3924 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3925 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3926
3927 if (time_left_ms < 0 ||
3928 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3929 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3930 _collection_set.optional_region_length(), time_left_ms);
3931 break;
3932 }
3933
3934 {
3935 Ticks start = Ticks::now();
3936 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3937 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3938 }
3939
3940 {
3941 Ticks start = Ticks::now();
3942 evacuate_next_optional_regions(per_thread_states);
3943 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3944 }
3945 }
3946
3947 _collection_set.abandon_optional_collection_set(per_thread_states);
3948 }
3949
3950 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3951 G1RedirtyCardsQueueSet* rdcqs,
3952 G1ParScanThreadStateSet* per_thread_states) {
3953 G1GCPhaseTimes* p = phase_times();
3954
3955 rem_set()->cleanup_after_scan_heap_roots();
3956
3957 // Process any discovered reference objects - we have
3958 // to do this _before_ we retire the GC alloc regions
3959 // as we may have to copy some 'reachable' referent
3960 // objects (and their reachable sub-graphs) that were
3961 // not copied during the pause.
3962 process_discovered_references(per_thread_states);
3963
3964 G1STWIsAliveClosure is_alive(this);
3965 G1KeepAliveClosure keep_alive(this);
3966
3967 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3968
3969 if (G1StringDedup::is_enabled()) {
3970 double string_dedup_time_ms = os::elapsedTime();
3971
3972 string_dedup_cleaning(&is_alive, &keep_alive, p);
3973
3974 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3975 p->record_string_deduplication_time(string_cleanup_time_ms);
3976 }
3977
3978 _allocator->release_gc_alloc_regions(evacuation_info);
3979
3980 if (evacuation_failed()) {
3981 restore_after_evac_failure(rdcqs);
3982
3983 // Reset the G1EvacuationFailureALot counters and flags
3984 NOT_PRODUCT(reset_evacuation_should_fail();)
3985
3986 double recalculate_used_start = os::elapsedTime();
3987 set_used(recalculate_used());
3988 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3989
3990 if (_archive_allocator != NULL) {
3991 _archive_allocator->clear_used();
3992 }
3993 for (uint i = 0; i < ParallelGCThreads; i++) {
3994 if (_evacuation_failed_info_array[i].has_failed()) {
3995 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3996 }
3997 }
3998 } else {
3999 // The "used" of the the collection set have already been subtracted
4000 // when they were freed. Add in the bytes used.
4001 increase_used(_bytes_used_during_gc);
4002 }
4003
4004 _preserved_marks_set.assert_empty();
4005
4006 merge_per_thread_state_info(per_thread_states);
4007
4008 // Reset and re-enable the hot card cache.
4009 // Note the counts for the cards in the regions in the
4010 // collection set are reset when the collection set is freed.
4011 _hot_card_cache->reset_hot_cache();
4012 _hot_card_cache->set_use_cache(true);
4013
4014 purge_code_root_memory();
4015
4016 redirty_logged_cards(rdcqs);
4017
4018 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4019
4020 eagerly_reclaim_humongous_regions();
4021
4022 record_obj_copy_mem_stats();
4023
4024 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4025 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4026
4027 #if COMPILER2_OR_JVMCI
4028 double start = os::elapsedTime();
4029 DerivedPointerTable::update_pointers();
4030 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4031 #endif
4032 policy()->print_age_table();
4033 }
4034
4035 void G1CollectedHeap::record_obj_copy_mem_stats() {
4036 policy()->old_gen_alloc_tracker()->
4037 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4038
4039 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4040 create_g1_evac_summary(&_old_evac_stats));
4041 }
4042
4043 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4044 assert(!hr->is_free(), "the region should not be free");
4045 assert(!hr->is_empty(), "the region should not be empty");
4046 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4047
4048 if (G1VerifyBitmaps) {
4049 MemRegion mr(hr->bottom(), hr->end());
4050 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4051 }
4052
4053 // Clear the card counts for this region.
4054 // Note: we only need to do this if the region is not young
4055 // (since we don't refine cards in young regions).
4056 if (!hr->is_young()) {
4057 _hot_card_cache->reset_card_counts(hr);
4058 }
4059
4060 // Reset region metadata to allow reuse.
4061 hr->hr_clear(true /* clear_space */);
4062 _policy->remset_tracker()->update_at_free(hr);
4063
4064 if (free_list != NULL) {
4065 free_list->add_ordered(hr);
4066 }
4067 }
4068
4069 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4070 FreeRegionList* free_list) {
4071 assert(hr->is_humongous(), "this is only for humongous regions");
4072 assert(free_list != NULL, "pre-condition");
4073 hr->clear_humongous();
4074 free_region(hr, free_list);
4075 }
4076
4077 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4078 const uint humongous_regions_removed) {
4079 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4080 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4081 _old_set.bulk_remove(old_regions_removed);
4082 _humongous_set.bulk_remove(humongous_regions_removed);
4083 }
4084
4085 }
4086
4087 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4088 assert(list != NULL, "list can't be null");
4089 if (!list->is_empty()) {
4090 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4091 _hrm->insert_list_into_free_list(list);
4092 }
4093 }
4094
4095 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4096 decrease_used(bytes);
4097 }
4098
4099 class G1FreeCollectionSetTask : public AbstractGangTask {
4100 // Helper class to keep statistics for the collection set freeing
4101 class FreeCSetStats {
4102 size_t _before_used_bytes; // Usage in regions successfully evacutate
4103 size_t _after_used_bytes; // Usage in regions failing evacuation
4104 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4105 size_t _failure_used_words; // Live size in failed regions
4106 size_t _failure_waste_words; // Wasted size in failed regions
4107 size_t _rs_length; // Remembered set size
4108 uint _regions_freed; // Number of regions freed
4109 public:
4110 FreeCSetStats() :
4111 _before_used_bytes(0),
4112 _after_used_bytes(0),
4113 _bytes_allocated_in_old_since_last_gc(0),
4114 _failure_used_words(0),
4115 _failure_waste_words(0),
4116 _rs_length(0),
4117 _regions_freed(0) { }
4118
4119 void merge_stats(FreeCSetStats* other) {
4120 assert(other != NULL, "invariant");
4121 _before_used_bytes += other->_before_used_bytes;
4122 _after_used_bytes += other->_after_used_bytes;
4123 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4124 _failure_used_words += other->_failure_used_words;
4125 _failure_waste_words += other->_failure_waste_words;
4126 _rs_length += other->_rs_length;
4127 _regions_freed += other->_regions_freed;
4128 }
4129
4130 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4131 evacuation_info->set_regions_freed(_regions_freed);
4132 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4133
4134 g1h->decrement_summary_bytes(_before_used_bytes);
4135 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4136
4137 G1Policy *policy = g1h->policy();
4138 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4139 policy->record_rs_length(_rs_length);
4140 policy->cset_regions_freed();
4141 }
4142
4143 void account_failed_region(HeapRegion* r) {
4144 size_t used_words = r->marked_bytes() / HeapWordSize;
4145 _failure_used_words += used_words;
4146 _failure_waste_words += HeapRegion::GrainWords - used_words;
4147 _after_used_bytes += r->used();
4148
4149 // When moving a young gen region to old gen, we "allocate" that whole
4150 // region there. This is in addition to any already evacuated objects.
4151 // Notify the policy about that. Old gen regions do not cause an
4152 // additional allocation: both the objects still in the region and the
4153 // ones already moved are accounted for elsewhere.
4154 if (r->is_young()) {
4155 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4156 }
4157 }
4158
4159 void account_evacuated_region(HeapRegion* r) {
4160 _before_used_bytes += r->used();
4161 _regions_freed += 1;
4162 }
4163
4164 void account_rs_length(HeapRegion* r) {
4165 _rs_length += r->rem_set()->occupied();
4166 }
4167 };
4168
4169 // Closure applied to all regions in the collection set.
4170 class FreeCSetClosure : public HeapRegionClosure {
4171 // Helper to send JFR events for regions.
4172 class JFREventForRegion {
4173 EventGCPhaseParallel _event;
4174 public:
4175 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4176 _event.set_gcId(GCId::current());
4177 _event.set_gcWorkerId(worker_id);
4178 if (region->is_young()) {
4179 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4180 } else {
4181 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4182 }
4183 }
4184
4185 ~JFREventForRegion() {
4186 _event.commit();
4187 }
4188 };
4189
4190 // Helper to do timing for region work.
4191 class TimerForRegion {
4192 Tickspan& _time;
4193 Ticks _start_time;
4194 public:
4195 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4196 ~TimerForRegion() {
4197 _time += Ticks::now() - _start_time;
4198 }
4199 };
4200
4201 // FreeCSetClosure members
4202 G1CollectedHeap* _g1h;
4203 const size_t* _surviving_young_words;
4204 uint _worker_id;
4205 Tickspan _young_time;
4206 Tickspan _non_young_time;
4207 FreeCSetStats* _stats;
4208
4209 void assert_in_cset(HeapRegion* r) {
4210 assert(r->young_index_in_cset() != 0 &&
4211 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4212 "Young index %u is wrong for region %u of type %s with %u young regions",
4213 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4214 }
4215
4216 void handle_evacuated_region(HeapRegion* r) {
4217 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4218 stats()->account_evacuated_region(r);
4219
4220 // Free the region and and its remembered set.
4221 _g1h->free_region(r, NULL);
4222 }
4223
4224 void handle_failed_region(HeapRegion* r) {
4225 // Do some allocation statistics accounting. Regions that failed evacuation
4226 // are always made old, so there is no need to update anything in the young
4227 // gen statistics, but we need to update old gen statistics.
4228 stats()->account_failed_region(r);
4229
4230 // Update the region state due to the failed evacuation.
4231 r->handle_evacuation_failure();
4232
4233 // Add region to old set, need to hold lock.
4234 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4235 _g1h->old_set_add(r);
4236 }
4237
4238 Tickspan& timer_for_region(HeapRegion* r) {
4239 return r->is_young() ? _young_time : _non_young_time;
4240 }
4241
4242 FreeCSetStats* stats() {
4243 return _stats;
4244 }
4245 public:
4246 FreeCSetClosure(const size_t* surviving_young_words,
4247 uint worker_id,
4248 FreeCSetStats* stats) :
4249 HeapRegionClosure(),
4250 _g1h(G1CollectedHeap::heap()),
4251 _surviving_young_words(surviving_young_words),
4252 _worker_id(worker_id),
4253 _young_time(),
4254 _non_young_time(),
4255 _stats(stats) { }
4256
4257 virtual bool do_heap_region(HeapRegion* r) {
4258 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4259 JFREventForRegion event(r, _worker_id);
4260 TimerForRegion timer(timer_for_region(r));
4261
4262 _g1h->clear_region_attr(r);
4263 stats()->account_rs_length(r);
4264
4265 if (r->is_young()) {
4266 assert_in_cset(r);
4267 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4268 }
4269
4270 if (r->evacuation_failed()) {
4271 handle_failed_region(r);
4272 } else {
4273 handle_evacuated_region(r);
4274 }
4275 assert(!_g1h->is_on_master_free_list(r), "sanity");
4276
4277 return false;
4278 }
4279
4280 void report_timing(Tickspan parallel_time) {
4281 G1GCPhaseTimes* pt = _g1h->phase_times();
4282 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4283 if (_young_time.value() > 0) {
4284 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4285 }
4286 if (_non_young_time.value() > 0) {
4287 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4288 }
4289 }
4290 };
4291
4292 // G1FreeCollectionSetTask members
4293 G1CollectedHeap* _g1h;
4294 G1EvacuationInfo* _evacuation_info;
4295 FreeCSetStats* _worker_stats;
4296 HeapRegionClaimer _claimer;
4297 const size_t* _surviving_young_words;
4298 uint _active_workers;
4299
4300 FreeCSetStats* worker_stats(uint worker) {
4301 return &_worker_stats[worker];
4302 }
4303
4304 void report_statistics() {
4305 // Merge the accounting
4306 FreeCSetStats total_stats;
4307 for (uint worker = 0; worker < _active_workers; worker++) {
4308 total_stats.merge_stats(worker_stats(worker));
4309 }
4310 total_stats.report(_g1h, _evacuation_info);
4311 }
4312
4313 public:
4314 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4315 AbstractGangTask("G1 Free Collection Set"),
4316 _g1h(G1CollectedHeap::heap()),
4317 _evacuation_info(evacuation_info),
4318 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4319 _claimer(active_workers),
4320 _surviving_young_words(surviving_young_words),
4321 _active_workers(active_workers) {
4322 for (uint worker = 0; worker < active_workers; worker++) {
4323 ::new (&_worker_stats[worker]) FreeCSetStats();
4324 }
4325 }
4326
4327 ~G1FreeCollectionSetTask() {
4328 Ticks serial_time = Ticks::now();
4329 report_statistics();
4330 for (uint worker = 0; worker < _active_workers; worker++) {
4331 _worker_stats[worker].~FreeCSetStats();
4332 }
4333 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4334 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4335 }
4336
4337 virtual void work(uint worker_id) {
4338 EventGCPhaseParallel event;
4339 Ticks start = Ticks::now();
4340 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4341 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4342
4343 // Report the total parallel time along with some more detailed metrics.
4344 cl.report_timing(Ticks::now() - start);
4345 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4346 }
4347 };
4348
4349 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4350 _eden.clear();
4351
4352 // The free collections set is split up in two tasks, the first
4353 // frees the collection set and records what regions are free,
4354 // and the second one rebuilds the free list. This proved to be
4355 // more efficient than adding a sorted list to another.
4356
4357 Ticks free_cset_start_time = Ticks::now();
4358 {
4359 uint const num_cs_regions = _collection_set.region_length();
4360 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4361 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4362
4363 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4364 cl.name(), num_workers, num_cs_regions, num_regions());
4365 workers()->run_task(&cl, num_workers);
4366 }
4367
4368 Ticks free_cset_end_time = Ticks::now();
4369 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4370
4371 // Now rebuild the free region list.
4372 hrm()->rebuild_free_list(workers());
4373 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4374
4375 collection_set->clear();
4376 }
4377
4378 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4379 private:
4380 FreeRegionList* _free_region_list;
4381 HeapRegionSet* _proxy_set;
4382 uint _humongous_objects_reclaimed;
4383 uint _humongous_regions_reclaimed;
4384 size_t _freed_bytes;
4385 public:
4386
4387 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4388 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4389 }
4390
4391 virtual bool do_heap_region(HeapRegion* r) {
4392 if (!r->is_starts_humongous()) {
4393 return false;
4394 }
4395
4396 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4397
4398 oop obj = (oop)r->bottom();
4399 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4400
4401 // The following checks whether the humongous object is live are sufficient.
4402 // The main additional check (in addition to having a reference from the roots
4403 // or the young gen) is whether the humongous object has a remembered set entry.
4404 //
4405 // A humongous object cannot be live if there is no remembered set for it
4406 // because:
4407 // - there can be no references from within humongous starts regions referencing
4408 // the object because we never allocate other objects into them.
4409 // (I.e. there are no intra-region references that may be missed by the
4410 // remembered set)
4411 // - as soon there is a remembered set entry to the humongous starts region
4412 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4413 // until the end of a concurrent mark.
4414 //
4415 // It is not required to check whether the object has been found dead by marking
4416 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4417 // all objects allocated during that time are considered live.
4418 // SATB marking is even more conservative than the remembered set.
4419 // So if at this point in the collection there is no remembered set entry,
4420 // nobody has a reference to it.
4421 // At the start of collection we flush all refinement logs, and remembered sets
4422 // are completely up-to-date wrt to references to the humongous object.
4423 //
4424 // Other implementation considerations:
4425 // - never consider object arrays at this time because they would pose
4426 // considerable effort for cleaning up the the remembered sets. This is
4427 // required because stale remembered sets might reference locations that
4428 // are currently allocated into.
4429 uint region_idx = r->hrm_index();
4430 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4431 !r->rem_set()->is_empty()) {
4432 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",
4433 region_idx,
4434 (size_t)obj->size() * HeapWordSize,
4435 p2i(r->bottom()),
4436 r->rem_set()->occupied(),
4437 r->rem_set()->strong_code_roots_list_length(),
4438 next_bitmap->is_marked(r->bottom()),
4439 g1h->is_humongous_reclaim_candidate(region_idx),
4440 obj->is_typeArray()
4441 );
4442 return false;
4443 }
4444
4445 guarantee(obj->is_typeArray(),
4446 "Only eagerly reclaiming type arrays is supported, but the object "
4447 PTR_FORMAT " is not.", p2i(r->bottom()));
4448
4449 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",
4450 region_idx,
4451 (size_t)obj->size() * HeapWordSize,
4452 p2i(r->bottom()),
4453 r->rem_set()->occupied(),
4454 r->rem_set()->strong_code_roots_list_length(),
4455 next_bitmap->is_marked(r->bottom()),
4456 g1h->is_humongous_reclaim_candidate(region_idx),
4457 obj->is_typeArray()
4458 );
4459
4460 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4461 cm->humongous_object_eagerly_reclaimed(r);
4462 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4463 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4464 region_idx,
4465 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4466 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4467 _humongous_objects_reclaimed++;
4468 do {
4469 HeapRegion* next = g1h->next_region_in_humongous(r);
4470 _freed_bytes += r->used();
4471 r->set_containing_set(NULL);
4472 _humongous_regions_reclaimed++;
4473 g1h->free_humongous_region(r, _free_region_list);
4474 r = next;
4475 } while (r != NULL);
4476
4477 return false;
4478 }
4479
4480 uint humongous_objects_reclaimed() {
4481 return _humongous_objects_reclaimed;
4482 }
4483
4484 uint humongous_regions_reclaimed() {
4485 return _humongous_regions_reclaimed;
4486 }
4487
4488 size_t bytes_freed() const {
4489 return _freed_bytes;
4490 }
4491 };
4492
4493 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4494 assert_at_safepoint_on_vm_thread();
4495
4496 if (!G1EagerReclaimHumongousObjects ||
4497 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4498 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4499 return;
4500 }
4501
4502 double start_time = os::elapsedTime();
4503
4504 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4505
4506 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4507 heap_region_iterate(&cl);
4508
4509 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4510
4511 G1HRPrinter* hrp = hr_printer();
4512 if (hrp->is_active()) {
4513 FreeRegionListIterator iter(&local_cleanup_list);
4514 while (iter.more_available()) {
4515 HeapRegion* hr = iter.get_next();
4516 hrp->cleanup(hr);
4517 }
4518 }
4519
4520 prepend_to_freelist(&local_cleanup_list);
4521 decrement_summary_bytes(cl.bytes_freed());
4522
4523 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4524 cl.humongous_objects_reclaimed());
4525 }
4526
4527 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4528 public:
4529 virtual bool do_heap_region(HeapRegion* r) {
4530 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4531 G1CollectedHeap::heap()->clear_region_attr(r);
4532 r->clear_young_index_in_cset();
4533 return false;
4534 }
4535 };
4536
4537 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4538 G1AbandonCollectionSetClosure cl;
4539 collection_set_iterate_all(&cl);
4540
4541 collection_set->clear();
4542 collection_set->stop_incremental_building();
4543 }
4544
4545 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4546 return _allocator->is_retained_old_region(hr);
4547 }
4548
4549 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4550 _eden.add(hr);
4551 _policy->set_region_eden(hr);
4552 }
4553
4554 #ifdef ASSERT
4555
4556 class NoYoungRegionsClosure: public HeapRegionClosure {
4557 private:
4558 bool _success;
4559 public:
4560 NoYoungRegionsClosure() : _success(true) { }
4561 bool do_heap_region(HeapRegion* r) {
4562 if (r->is_young()) {
4563 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4564 p2i(r->bottom()), p2i(r->end()));
4565 _success = false;
4566 }
4567 return false;
4568 }
4569 bool success() { return _success; }
4570 };
4571
4572 bool G1CollectedHeap::check_young_list_empty() {
4573 bool ret = (young_regions_count() == 0);
4574
4575 NoYoungRegionsClosure closure;
4576 heap_region_iterate(&closure);
4577 ret = ret && closure.success();
4578
4579 return ret;
4580 }
4581
4582 #endif // ASSERT
4583
4584 class TearDownRegionSetsClosure : public HeapRegionClosure {
4585 HeapRegionSet *_old_set;
4586
4587 public:
4588 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4589
4590 bool do_heap_region(HeapRegion* r) {
4591 if (r->is_old()) {
4592 _old_set->remove(r);
4593 } else if(r->is_young()) {
4594 r->uninstall_surv_rate_group();
4595 } else {
4596 // We ignore free regions, we'll empty the free list afterwards.
4597 // We ignore humongous and archive regions, we're not tearing down these
4598 // sets.
4599 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4600 "it cannot be another type");
4601 }
4602 return false;
4603 }
4604
4605 ~TearDownRegionSetsClosure() {
4606 assert(_old_set->is_empty(), "post-condition");
4607 }
4608 };
4609
4610 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4611 assert_at_safepoint_on_vm_thread();
4612
4613 if (!free_list_only) {
4614 TearDownRegionSetsClosure cl(&_old_set);
4615 heap_region_iterate(&cl);
4616
4617 // Note that emptying the _young_list is postponed and instead done as
4618 // the first step when rebuilding the regions sets again. The reason for
4619 // this is that during a full GC string deduplication needs to know if
4620 // a collected region was young or old when the full GC was initiated.
4621 }
4622 _hrm->remove_all_free_regions();
4623 }
4624
4625 void G1CollectedHeap::increase_used(size_t bytes) {
4626 _summary_bytes_used += bytes;
4627 }
4628
4629 void G1CollectedHeap::decrease_used(size_t bytes) {
4630 assert(_summary_bytes_used >= bytes,
4631 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4632 _summary_bytes_used, bytes);
4633 _summary_bytes_used -= bytes;
4634 }
4635
4636 void G1CollectedHeap::set_used(size_t bytes) {
4637 _summary_bytes_used = bytes;
4638 }
4639
4640 class RebuildRegionSetsClosure : public HeapRegionClosure {
4641 private:
4642 bool _free_list_only;
4643
4644 HeapRegionSet* _old_set;
4645 HeapRegionManager* _hrm;
4646
4647 size_t _total_used;
4648
4649 public:
4650 RebuildRegionSetsClosure(bool free_list_only,
4651 HeapRegionSet* old_set,
4652 HeapRegionManager* hrm) :
4653 _free_list_only(free_list_only),
4654 _old_set(old_set), _hrm(hrm), _total_used(0) {
4655 assert(_hrm->num_free_regions() == 0, "pre-condition");
4656 if (!free_list_only) {
4657 assert(_old_set->is_empty(), "pre-condition");
4658 }
4659 }
4660
4661 bool do_heap_region(HeapRegion* r) {
4662 if (r->is_empty()) {
4663 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4664 // Add free regions to the free list
4665 r->set_free();
4666 _hrm->insert_into_free_list(r);
4667 } else if (!_free_list_only) {
4668 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4669
4670 if (r->is_archive() || r->is_humongous()) {
4671 // We ignore archive and humongous regions. We left these sets unchanged.
4672 } else {
4673 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4674 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4675 r->move_to_old();
4676 _old_set->add(r);
4677 }
4678 _total_used += r->used();
4679 }
4680
4681 return false;
4682 }
4683
4684 size_t total_used() {
4685 return _total_used;
4686 }
4687 };
4688
4689 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4690 assert_at_safepoint_on_vm_thread();
4691
4692 if (!free_list_only) {
4693 _eden.clear();
4694 _survivor.clear();
4695 }
4696
4697 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4698 heap_region_iterate(&cl);
4699
4700 if (!free_list_only) {
4701 set_used(cl.total_used());
4702 if (_archive_allocator != NULL) {
4703 _archive_allocator->clear_used();
4704 }
4705 }
4706 assert_used_and_recalculate_used_equal(this);
4707 }
4708
4709 // Methods for the mutator alloc region
4710
4711 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4712 bool force,
4713 uint node_index) {
4714 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4715 bool should_allocate = policy()->should_allocate_mutator_region();
4716 if (force || should_allocate) {
4717 HeapRegion* new_alloc_region = new_region(word_size,
4718 HeapRegionType::Eden,
4719 false /* do_expand */,
4720 node_index);
4721 if (new_alloc_region != NULL) {
4722 set_region_short_lived_locked(new_alloc_region);
4723 _hr_printer.alloc(new_alloc_region, !should_allocate);
4724 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4725 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4726 return new_alloc_region;
4727 }
4728 }
4729 return NULL;
4730 }
4731
4732 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4733 size_t allocated_bytes) {
4734 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4735 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4736
4737 collection_set()->add_eden_region(alloc_region);
4738 increase_used(allocated_bytes);
4739 _eden.add_used_bytes(allocated_bytes);
4740 _hr_printer.retire(alloc_region);
4741
4742 // We update the eden sizes here, when the region is retired,
4743 // instead of when it's allocated, since this is the point that its
4744 // used space has been recorded in _summary_bytes_used.
4745 g1mm()->update_eden_size();
4746 }
4747
4748 // Methods for the GC alloc regions
4749
4750 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4751 if (dest.is_old()) {
4752 return true;
4753 } else {
4754 return survivor_regions_count() < policy()->max_survivor_regions();
4755 }
4756 }
4757
4758 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4759 assert(FreeList_lock->owned_by_self(), "pre-condition");
4760
4761 if (!has_more_regions(dest)) {
4762 return NULL;
4763 }
4764
4765 HeapRegionType type;
4766 if (dest.is_young()) {
4767 type = HeapRegionType::Survivor;
4768 } else {
4769 type = HeapRegionType::Old;
4770 }
4771
4772 HeapRegion* new_alloc_region = new_region(word_size,
4773 type,
4774 true /* do_expand */,
4775 node_index);
4776
4777 if (new_alloc_region != NULL) {
4778 if (type.is_survivor()) {
4779 new_alloc_region->set_survivor();
4780 _survivor.add(new_alloc_region);
4781 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4782 } else {
4783 new_alloc_region->set_old();
4784 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4785 }
4786 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4787 register_region_with_region_attr(new_alloc_region);
4788 _hr_printer.alloc(new_alloc_region);
4789 return new_alloc_region;
4790 }
4791 return NULL;
4792 }
4793
4794 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4795 size_t allocated_bytes,
4796 G1HeapRegionAttr dest) {
4797 _bytes_used_during_gc += allocated_bytes;
4798 if (dest.is_old()) {
4799 old_set_add(alloc_region);
4800 } else {
4801 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4802 _survivor.add_used_bytes(allocated_bytes);
4803 }
4804
4805 bool const during_im = collector_state()->in_concurrent_start_gc();
4806 if (during_im && allocated_bytes > 0) {
4807 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4808 }
4809 _hr_printer.retire(alloc_region);
4810 }
4811
4812 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4813 bool expanded = false;
4814 uint index = _hrm->find_highest_free(&expanded);
4815
4816 if (index != G1_NO_HRM_INDEX) {
4817 if (expanded) {
4818 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4819 HeapRegion::GrainWords * HeapWordSize);
4820 }
4821 return _hrm->allocate_free_regions_starting_at(index, 1);
4822 }
4823 return NULL;
4824 }
4825
4826 // Optimized nmethod scanning
4827
4828 class RegisterNMethodOopClosure: public OopClosure {
4829 G1CollectedHeap* _g1h;
4830 nmethod* _nm;
4831
4832 template <class T> void do_oop_work(T* p) {
4833 T heap_oop = RawAccess<>::oop_load(p);
4834 if (!CompressedOops::is_null(heap_oop)) {
4835 oop obj = CompressedOops::decode_not_null(heap_oop);
4836 HeapRegion* hr = _g1h->heap_region_containing(obj);
4837 assert(!hr->is_continues_humongous(),
4838 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4839 " starting at " HR_FORMAT,
4840 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4841
4842 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4843 hr->add_strong_code_root_locked(_nm);
4844 }
4845 }
4846
4847 public:
4848 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4849 _g1h(g1h), _nm(nm) {}
4850
4851 void do_oop(oop* p) { do_oop_work(p); }
4852 void do_oop(narrowOop* p) { do_oop_work(p); }
4853 };
4854
4855 class UnregisterNMethodOopClosure: public OopClosure {
4856 G1CollectedHeap* _g1h;
4857 nmethod* _nm;
4858
4859 template <class T> void do_oop_work(T* p) {
4860 T heap_oop = RawAccess<>::oop_load(p);
4861 if (!CompressedOops::is_null(heap_oop)) {
4862 oop obj = CompressedOops::decode_not_null(heap_oop);
4863 HeapRegion* hr = _g1h->heap_region_containing(obj);
4864 assert(!hr->is_continues_humongous(),
4865 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4866 " starting at " HR_FORMAT,
4867 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4868
4869 hr->remove_strong_code_root(_nm);
4870 }
4871 }
4872
4873 public:
4874 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4875 _g1h(g1h), _nm(nm) {}
4876
4877 void do_oop(oop* p) { do_oop_work(p); }
4878 void do_oop(narrowOop* p) { do_oop_work(p); }
4879 };
4880
4881 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4882 guarantee(nm != NULL, "sanity");
4883 RegisterNMethodOopClosure reg_cl(this, nm);
4884 nm->oops_do(®_cl);
4885 }
4886
4887 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4888 guarantee(nm != NULL, "sanity");
4889 UnregisterNMethodOopClosure reg_cl(this, nm);
4890 nm->oops_do(®_cl, true);
4891 }
4892
4893 void G1CollectedHeap::purge_code_root_memory() {
4894 double purge_start = os::elapsedTime();
4895 G1CodeRootSet::purge();
4896 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4897 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4898 }
4899
4900 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4901 G1CollectedHeap* _g1h;
4902
4903 public:
4904 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4905 _g1h(g1h) {}
4906
4907 void do_code_blob(CodeBlob* cb) {
4908 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4909 if (nm == NULL) {
4910 return;
4911 }
4912
4913 _g1h->register_nmethod(nm);
4914 }
4915 };
4916
4917 void G1CollectedHeap::rebuild_strong_code_roots() {
4918 RebuildStrongCodeRootClosure blob_cl(this);
4919 CodeCache::blobs_do(&blob_cl);
4920 }
4921
4922 void G1CollectedHeap::initialize_serviceability() {
4923 _g1mm->initialize_serviceability();
4924 }
4925
4926 MemoryUsage G1CollectedHeap::memory_usage() {
4927 return _g1mm->memory_usage();
4928 }
4929
4930 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4931 return _g1mm->memory_managers();
4932 }
4933
4934 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4935 return _g1mm->memory_pools();
4936 }