1 /*
2 * Copyright (c) 2001, 2022, 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.
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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 "compiler/oopMap.hpp"
32 #include "gc/g1/g1Allocator.inline.hpp"
33 #include "gc/g1/g1Arguments.hpp"
34 #include "gc/g1/g1BarrierSet.hpp"
35 #include "gc/g1/g1BatchedTask.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectionSetCandidates.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1ConcurrentRefine.hpp"
41 #include "gc/g1/g1ConcurrentRefineThread.hpp"
42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
43 #include "gc/g1/g1DirtyCardQueue.hpp"
44 #include "gc/g1/g1EvacStats.inline.hpp"
45 #include "gc/g1/g1FullCollector.hpp"
46 #include "gc/g1/g1GCCounters.hpp"
47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
48 #include "gc/g1/g1GCPhaseTimes.hpp"
49 #include "gc/g1/g1GCPauseType.hpp"
50 #include "gc/g1/g1HeapSizingPolicy.hpp"
51 #include "gc/g1/g1HeapTransition.hpp"
52 #include "gc/g1/g1HeapVerifier.hpp"
53 #include "gc/g1/g1HotCardCache.hpp"
54 #include "gc/g1/g1InitLogger.hpp"
55 #include "gc/g1/g1MemoryPool.hpp"
56 #include "gc/g1/g1OopClosures.inline.hpp"
57 #include "gc/g1/g1ParallelCleaning.hpp"
58 #include "gc/g1/g1ParScanThreadState.inline.hpp"
59 #include "gc/g1/g1PeriodicGCTask.hpp"
60 #include "gc/g1/g1Policy.hpp"
61 #include "gc/g1/g1RedirtyCardsQueue.hpp"
62 #include "gc/g1/g1RegionToSpaceMapper.hpp"
63 #include "gc/g1/g1RemSet.hpp"
64 #include "gc/g1/g1RootClosures.hpp"
65 #include "gc/g1/g1RootProcessor.hpp"
66 #include "gc/g1/g1SATBMarkQueueSet.hpp"
67 #include "gc/g1/g1SegmentedArrayFreeMemoryTask.hpp"
68 #include "gc/g1/g1ServiceThread.hpp"
69 #include "gc/g1/g1ThreadLocalData.hpp"
70 #include "gc/g1/g1Trace.hpp"
71 #include "gc/g1/g1UncommitRegionTask.hpp"
72 #include "gc/g1/g1VMOperations.hpp"
73 #include "gc/g1/g1YoungCollector.hpp"
74 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp"
75 #include "gc/g1/heapRegion.inline.hpp"
76 #include "gc/g1/heapRegionRemSet.inline.hpp"
77 #include "gc/g1/heapRegionSet.inline.hpp"
78 #include "gc/shared/concurrentGCBreakpoints.hpp"
79 #include "gc/shared/gcBehaviours.hpp"
80 #include "gc/shared/gcHeapSummary.hpp"
81 #include "gc/shared/gcId.hpp"
82 #include "gc/shared/gcLocker.hpp"
83 #include "gc/shared/gcTimer.hpp"
84 #include "gc/shared/gcTraceTime.inline.hpp"
85 #include "gc/shared/generationSpec.hpp"
86 #include "gc/shared/isGCActiveMark.hpp"
87 #include "gc/shared/locationPrinter.inline.hpp"
88 #include "gc/shared/oopStorageParState.hpp"
89 #include "gc/shared/preservedMarks.inline.hpp"
90 #include "gc/shared/slidingForwarding.inline.hpp"
91 #include "gc/shared/suspendibleThreadSet.hpp"
92 #include "gc/shared/referenceProcessor.inline.hpp"
93 #include "gc/shared/suspendibleThreadSet.hpp"
94 #include "gc/shared/taskqueue.inline.hpp"
95 #include "gc/shared/taskTerminator.hpp"
96 #include "gc/shared/tlab_globals.hpp"
97 #include "gc/shared/workerPolicy.hpp"
98 #include "gc/shared/weakProcessor.inline.hpp"
99 #include "logging/log.hpp"
100 #include "memory/allocation.hpp"
101 #include "memory/heapInspection.hpp"
102 #include "memory/iterator.hpp"
103 #include "memory/metaspaceUtils.hpp"
104 #include "memory/resourceArea.hpp"
105 #include "memory/universe.hpp"
106 #include "oops/access.inline.hpp"
107 #include "oops/compressedOops.inline.hpp"
108 #include "oops/oop.inline.hpp"
109 #include "runtime/atomic.hpp"
110 #include "runtime/handles.inline.hpp"
111 #include "runtime/init.hpp"
112 #include "runtime/java.hpp"
113 #include "runtime/orderAccess.hpp"
114 #include "runtime/threadSMR.hpp"
115 #include "runtime/vmThread.hpp"
116 #include "utilities/align.hpp"
117 #include "utilities/autoRestore.hpp"
118 #include "utilities/bitMap.inline.hpp"
119 #include "utilities/globalDefinitions.hpp"
120 #include "utilities/stack.inline.hpp"
121
122 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
123
124 // INVARIANTS/NOTES
125 //
126 // All allocation activity covered by the G1CollectedHeap interface is
127 // serialized by acquiring the HeapLock. This happens in mem_allocate
128 // and allocate_new_tlab, which are the "entry" points to the
129 // allocation code from the rest of the JVM. (Note that this does not
130 // apply to TLAB allocation, which is not part of this interface: it
131 // is done by clients of this interface.)
132
133 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
134 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
135 }
136
137 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
138 // The from card cache is not the memory that is actually committed. So we cannot
139 // take advantage of the zero_filled parameter.
140 reset_from_card_cache(start_idx, num_regions);
141 }
142
143 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
144 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
145 cl->set_max_workers(num_workers);
146 workers()->run_task(cl, num_workers);
147 }
148
149 uint G1CollectedHeap::get_chunks_per_region() {
150 uint log_region_size = HeapRegion::LogOfHRGrainBytes;
151 // Limit the expected input values to current known possible values of the
152 // (log) region size. Adjust as necessary after testing if changing the permissible
153 // values for region size.
154 assert(log_region_size >= 20 && log_region_size <= 29,
155 "expected value in [20,29], but got %u", log_region_size);
156 return 1u << (log_region_size / 2 - 4);
157 }
158
159 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
160 MemRegion mr) {
161 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
162 }
163
164 // Private methods.
165
166 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
167 HeapRegionType type,
168 bool do_expand,
169 uint node_index) {
170 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
171 "the only time we use this to allocate a humongous region is "
172 "when we are allocating a single humongous region");
173
174 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
175
176 if (res == NULL && do_expand) {
177 // Currently, only attempts to allocate GC alloc regions set
178 // do_expand to true. So, we should only reach here during a
179 // safepoint.
180 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
181
182 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
183 word_size * HeapWordSize);
184
185 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
186 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
187 word_size * HeapWordSize);
188 if (expand_single_region(node_index)) {
189 // Given that expand_single_region() succeeded in expanding the heap, and we
190 // always expand the heap by an amount aligned to the heap
191 // region size, the free list should in theory not be empty.
192 // In either case allocate_free_region() will check for NULL.
193 res = _hrm.allocate_free_region(type, node_index);
194 }
195 }
196 return res;
197 }
198
199 HeapWord*
200 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
201 uint num_regions,
202 size_t word_size) {
203 assert(first_hr != NULL, "pre-condition");
204 assert(is_humongous(word_size), "word_size should be humongous");
205 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
206
207 // Index of last region in the series.
208 uint first = first_hr->hrm_index();
209 uint last = first + num_regions - 1;
210
211 // We need to initialize the region(s) we just discovered. This is
212 // a bit tricky given that it can happen concurrently with
213 // refinement threads refining cards on these regions and
214 // potentially wanting to refine the BOT as they are scanning
215 // those cards (this can happen shortly after a cleanup; see CR
216 // 6991377). So we have to set up the region(s) carefully and in
217 // a specific order.
218
219 // The word size sum of all the regions we will allocate.
220 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
221 assert(word_size <= word_size_sum, "sanity");
222
223 // The passed in hr will be the "starts humongous" region. The header
224 // of the new object will be placed at the bottom of this region.
225 HeapWord* new_obj = first_hr->bottom();
226 // This will be the new top of the new object.
227 HeapWord* obj_top = new_obj + word_size;
228
229 // First, we need to zero the header of the space that we will be
230 // allocating. When we update top further down, some refinement
231 // threads might try to scan the region. By zeroing the header we
232 // ensure that any thread that will try to scan the region will
233 // come across the zero klass word and bail out.
234 //
235 // NOTE: It would not have been correct to have used
236 // CollectedHeap::fill_with_object() and make the space look like
237 // an int array. The thread that is doing the allocation will
238 // later update the object header to a potentially different array
239 // type and, for a very short period of time, the klass and length
240 // fields will be inconsistent. This could cause a refinement
241 // thread to calculate the object size incorrectly.
242 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
243
244 // Next, pad out the unused tail of the last region with filler
245 // objects, for improved usage accounting.
246 // How many words we use for filler objects.
247 size_t word_fill_size = word_size_sum - word_size;
248
249 // How many words memory we "waste" which cannot hold a filler object.
250 size_t words_not_fillable = 0;
251
252 if (word_fill_size >= min_fill_size()) {
253 fill_with_objects(obj_top, word_fill_size);
254 } else if (word_fill_size > 0) {
255 // We have space to fill, but we cannot fit an object there.
256 words_not_fillable = word_fill_size;
257 word_fill_size = 0;
258 }
259
260 // We will set up the first region as "starts humongous". This
261 // will also update the BOT covering all the regions to reflect
262 // that there is a single object that starts at the bottom of the
263 // first region.
264 first_hr->set_starts_humongous(obj_top, word_fill_size);
265 _policy->remset_tracker()->update_at_allocate(first_hr);
266 // Then, if there are any, we will set up the "continues
267 // humongous" regions.
268 HeapRegion* hr = NULL;
269 for (uint i = first + 1; i <= last; ++i) {
270 hr = region_at(i);
271 hr->set_continues_humongous(first_hr);
272 _policy->remset_tracker()->update_at_allocate(hr);
273 }
274
275 // Up to this point no concurrent thread would have been able to
276 // do any scanning on any region in this series. All the top
277 // fields still point to bottom, so the intersection between
278 // [bottom,top] and [card_start,card_end] will be empty. Before we
279 // update the top fields, we'll do a storestore to make sure that
280 // no thread sees the update to top before the zeroing of the
281 // object header and the BOT initialization.
282 OrderAccess::storestore();
283
284 // Now, we will update the top fields of the "continues humongous"
285 // regions except the last one.
286 for (uint i = first; i < last; ++i) {
287 hr = region_at(i);
288 hr->set_top(hr->end());
289 }
290
291 hr = region_at(last);
292 // If we cannot fit a filler object, we must set top to the end
293 // of the humongous object, otherwise we cannot iterate the heap
294 // and the BOT will not be complete.
295 hr->set_top(hr->end() - words_not_fillable);
296
297 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
298 "obj_top should be in last region");
299
300 assert(words_not_fillable == 0 ||
301 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
302 "Miscalculation in humongous allocation");
303
304 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
305
306 for (uint i = first; i <= last; ++i) {
307 hr = region_at(i);
308 _humongous_set.add(hr);
309 _hr_printer.alloc(hr);
310 }
311
312 return new_obj;
313 }
314
315 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
316 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
317 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
318 }
319
320 // If could fit into free regions w/o expansion, try.
321 // Otherwise, if can expand, do so.
322 // Otherwise, if using ex regions might help, try with ex given back.
323 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
324 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
325
326 _verifier->verify_region_sets_optional();
327
328 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
329
330 // Policy: First try to allocate a humongous object in the free list.
331 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
332 if (humongous_start == NULL) {
333 // Policy: We could not find enough regions for the humongous object in the
334 // free list. Look through the heap to find a mix of free and uncommitted regions.
335 // If so, expand the heap and allocate the humongous object.
336 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
337 if (humongous_start != NULL) {
338 // We managed to find a region by expanding the heap.
339 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
340 word_size * HeapWordSize);
341 policy()->record_new_heap_size(num_regions());
342 } else {
343 // Policy: Potentially trigger a defragmentation GC.
344 }
345 }
346
347 HeapWord* result = NULL;
348 if (humongous_start != NULL) {
349 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
350 assert(result != NULL, "it should always return a valid result");
351
352 // A successful humongous object allocation changes the used space
353 // information of the old generation so we need to recalculate the
354 // sizes and update the jstat counters here.
355 monitoring_support()->update_sizes();
356 }
357
358 _verifier->verify_region_sets_optional();
359
360 return result;
361 }
362
363 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
364 size_t requested_size,
365 size_t* actual_size) {
366 assert_heap_not_locked_and_not_at_safepoint();
367 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
368
369 return attempt_allocation(min_size, requested_size, actual_size);
370 }
371
372 HeapWord*
373 G1CollectedHeap::mem_allocate(size_t word_size,
374 bool* gc_overhead_limit_was_exceeded) {
375 assert_heap_not_locked_and_not_at_safepoint();
376
377 if (is_humongous(word_size)) {
378 return attempt_allocation_humongous(word_size);
379 }
380 size_t dummy = 0;
381 return attempt_allocation(word_size, word_size, &dummy);
382 }
383
384 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
385 ResourceMark rm; // For retrieving the thread names in log messages.
386
387 // Make sure you read the note in attempt_allocation_humongous().
388
389 assert_heap_not_locked_and_not_at_safepoint();
390 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
391 "be called for humongous allocation requests");
392
393 // We should only get here after the first-level allocation attempt
394 // (attempt_allocation()) failed to allocate.
395
396 // We will loop until a) we manage to successfully perform the
397 // allocation or b) we successfully schedule a collection which
398 // fails to perform the allocation. b) is the only case when we'll
399 // return NULL.
400 HeapWord* result = NULL;
401 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
402 bool should_try_gc;
403 bool preventive_collection_required = false;
404 uint gc_count_before;
405
406 {
407 MutexLocker x(Heap_lock);
408
409 // Now that we have the lock, we first retry the allocation in case another
410 // thread changed the region while we were waiting to acquire the lock.
411 size_t actual_size;
412 result = _allocator->attempt_allocation(word_size, word_size, &actual_size);
413 if (result != NULL) {
414 return result;
415 }
416
417 preventive_collection_required = policy()->preventive_collection_required(1);
418 if (!preventive_collection_required) {
419 // We've already attempted a lock-free allocation above, so we don't want to
420 // do it again. Let's jump straight to replacing the active region.
421 result = _allocator->attempt_allocation_using_new_region(word_size);
422 if (result != NULL) {
423 return result;
424 }
425
426 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
427 // This is different to when only GCLocker::needs_gc() is set: try to avoid
428 // waiting because the GCLocker is active to not wait too long.
429 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
430 // No need for an ergo message here, can_expand_young_list() does this when
431 // it returns true.
432 result = _allocator->attempt_allocation_force(word_size);
433 if (result != NULL) {
434 return result;
435 }
436 }
437 }
438
439 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
440 // the GCLocker initiated GC has been performed and then retry. This includes
441 // the case when the GC Locker is not active but has not been performed.
442 should_try_gc = !GCLocker::needs_gc();
443 // Read the GC count while still holding the Heap_lock.
444 gc_count_before = total_collections();
445 }
446
447 if (should_try_gc) {
448 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
449 : GCCause::_g1_inc_collection_pause;
450 bool succeeded;
451 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
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 assert(_archive_allocator == nullptr, "should not be initialized");
512 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
513 }
514
515 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
516 // Allocations in archive regions cannot be of a size that would be considered
517 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
518 // may be different at archive-restore time.
519 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
520 }
521
522 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
523 assert_at_safepoint_on_vm_thread();
524 assert(_archive_allocator != nullptr, "_archive_allocator not initialized");
525 if (is_archive_alloc_too_large(word_size)) {
526 return nullptr;
527 }
528 return _archive_allocator->archive_mem_allocate(word_size);
529 }
530
531 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
532 size_t end_alignment_in_bytes) {
533 assert_at_safepoint_on_vm_thread();
534 assert(_archive_allocator != nullptr, "_archive_allocator not initialized");
535
536 // Call complete_archive to do the real work, filling in the MemRegion
537 // array with the archive regions.
538 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
539 delete _archive_allocator;
540 _archive_allocator = nullptr;
541 }
542
543 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
544 assert(ranges != NULL, "MemRegion array NULL");
545 assert(count != 0, "No MemRegions provided");
546 MemRegion reserved = _hrm.reserved();
547 for (size_t i = 0; i < count; i++) {
548 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
549 return false;
550 }
551 }
552 return true;
553 }
554
555 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
556 size_t count,
557 bool open) {
558 assert(!is_init_completed(), "Expect to be called at JVM init time");
559 assert(ranges != NULL, "MemRegion array NULL");
560 assert(count != 0, "No MemRegions provided");
561 MutexLocker x(Heap_lock);
562
563 MemRegion reserved = _hrm.reserved();
564 HeapWord* prev_last_addr = NULL;
565 HeapRegion* prev_last_region = NULL;
566
567 // Temporarily disable pretouching of heap pages. This interface is used
568 // when mmap'ing archived heap data in, so pre-touching is wasted.
569 FlagSetting fs(AlwaysPreTouch, false);
570
571 // For each specified MemRegion range, allocate the corresponding G1
572 // regions and mark them as archive regions. We expect the ranges
573 // in ascending starting address order, without overlap.
574 for (size_t i = 0; i < count; i++) {
575 MemRegion curr_range = ranges[i];
576 HeapWord* start_address = curr_range.start();
577 size_t word_size = curr_range.word_size();
578 HeapWord* last_address = curr_range.last();
579 size_t commits = 0;
580
581 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
582 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
583 p2i(start_address), p2i(last_address));
584 guarantee(start_address > prev_last_addr,
585 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
586 p2i(start_address), p2i(prev_last_addr));
587 prev_last_addr = last_address;
588
589 // Check for ranges that start in the same G1 region in which the previous
590 // range ended, and adjust the start address so we don't try to allocate
591 // the same region again. If the current range is entirely within that
592 // region, skip it, just adjusting the recorded top.
593 HeapRegion* start_region = _hrm.addr_to_region(start_address);
594 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
595 start_address = start_region->end();
596 if (start_address > last_address) {
597 increase_used(word_size * HeapWordSize);
598 start_region->set_top(last_address + 1);
599 continue;
600 }
601 start_region->set_top(start_address);
602 curr_range = MemRegion(start_address, last_address + 1);
603 start_region = _hrm.addr_to_region(start_address);
604 }
605
606 // Perform the actual region allocation, exiting if it fails.
607 // Then note how much new space we have allocated.
608 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
609 return false;
610 }
611 increase_used(word_size * HeapWordSize);
612 if (commits != 0) {
613 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
614 HeapRegion::GrainWords * HeapWordSize * commits);
615
616 }
617
618 // Mark each G1 region touched by the range as archive, add it to
619 // the old set, and set top.
620 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
621 HeapRegion* last_region = _hrm.addr_to_region(last_address);
622 prev_last_region = last_region;
623
624 while (curr_region != NULL) {
625 assert(curr_region->is_empty() && !curr_region->is_pinned(),
626 "Region already in use (index %u)", curr_region->hrm_index());
627 if (open) {
628 curr_region->set_open_archive();
629 } else {
630 curr_region->set_closed_archive();
631 }
632 _hr_printer.alloc(curr_region);
633 _archive_set.add(curr_region);
634 HeapWord* top;
635 HeapRegion* next_region;
636 if (curr_region != last_region) {
637 top = curr_region->end();
638 next_region = _hrm.next_region_in_heap(curr_region);
639 } else {
640 top = last_address + 1;
641 next_region = NULL;
642 }
643 curr_region->set_top(top);
644 curr_region = next_region;
645 }
646 }
647 return true;
648 }
649
650 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
651 assert(!is_init_completed(), "Expect to be called at JVM init time");
652 assert(ranges != NULL, "MemRegion array NULL");
653 assert(count != 0, "No MemRegions provided");
654 MemRegion reserved = _hrm.reserved();
655 HeapWord *prev_last_addr = NULL;
656 HeapRegion* prev_last_region = NULL;
657
658 // For each MemRegion, create filler objects, if needed, in the G1 regions
659 // that contain the address range. The address range actually within the
660 // MemRegion will not be modified. That is assumed to have been initialized
661 // elsewhere, probably via an mmap of archived heap data.
662 MutexLocker x(Heap_lock);
663 for (size_t i = 0; i < count; i++) {
664 HeapWord* start_address = ranges[i].start();
665 HeapWord* last_address = ranges[i].last();
666
667 assert(reserved.contains(start_address) && reserved.contains(last_address),
668 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
669 p2i(start_address), p2i(last_address));
670 assert(start_address > prev_last_addr,
671 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
672 p2i(start_address), p2i(prev_last_addr));
673
674 HeapRegion* start_region = _hrm.addr_to_region(start_address);
675 HeapRegion* last_region = _hrm.addr_to_region(last_address);
676 HeapWord* bottom_address = start_region->bottom();
677
678 // Check for a range beginning in the same region in which the
679 // previous one ended.
680 if (start_region == prev_last_region) {
681 bottom_address = prev_last_addr + 1;
682 }
683
684 // Verify that the regions were all marked as archive regions by
685 // alloc_archive_regions.
686 HeapRegion* curr_region = start_region;
687 while (curr_region != NULL) {
688 guarantee(curr_region->is_archive(),
689 "Expected archive region at index %u", curr_region->hrm_index());
690 if (curr_region != last_region) {
691 curr_region = _hrm.next_region_in_heap(curr_region);
692 } else {
693 curr_region = NULL;
694 }
695 }
696
697 prev_last_addr = last_address;
698 prev_last_region = last_region;
699
700 // Fill the memory below the allocated range with dummy object(s),
701 // if the region bottom does not match the range start, or if the previous
702 // range ended within the same G1 region, and there is a gap.
703 assert(start_address >= bottom_address, "bottom address should not be greater than start address");
704 if (start_address > bottom_address) {
705 size_t fill_size = pointer_delta(start_address, bottom_address);
706 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
707 increase_used(fill_size * HeapWordSize);
708 }
709 }
710 }
711
712 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
713 size_t desired_word_size,
714 size_t* actual_word_size) {
715 assert_heap_not_locked_and_not_at_safepoint();
716 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
717 "be called for humongous allocation requests");
718
719 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
720
721 if (result == NULL) {
722 *actual_word_size = desired_word_size;
723 result = attempt_allocation_slow(desired_word_size);
724 }
725
726 assert_heap_not_locked();
727 if (result != NULL) {
728 assert(*actual_word_size != 0, "Actual size must have been set here");
729 dirty_young_block(result, *actual_word_size);
730 } else {
731 *actual_word_size = 0;
732 }
733
734 return result;
735 }
736
737 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) {
738 assert(!is_init_completed(), "Expect to be called at JVM init time");
739 assert(ranges != NULL, "MemRegion array NULL");
740 assert(count != 0, "No MemRegions provided");
741
742 HeapWord* st = ranges[0].start();
743 HeapWord* last = ranges[count-1].last();
744 HeapRegion* hr_st = _hrm.addr_to_region(st);
745 HeapRegion* hr_last = _hrm.addr_to_region(last);
746
747 HeapRegion* hr_curr = hr_st;
748 while (hr_curr != NULL) {
749 hr_curr->update_bot();
750 if (hr_curr != hr_last) {
751 hr_curr = _hrm.next_region_in_heap(hr_curr);
752 } else {
753 hr_curr = NULL;
754 }
755 }
756 }
757
758 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
759 assert(!is_init_completed(), "Expect to be called at JVM init time");
760 assert(ranges != NULL, "MemRegion array NULL");
761 assert(count != 0, "No MemRegions provided");
762 MemRegion reserved = _hrm.reserved();
763 HeapWord* prev_last_addr = NULL;
764 HeapRegion* prev_last_region = NULL;
765 size_t size_used = 0;
766 uint shrink_count = 0;
767
768 // For each Memregion, free the G1 regions that constitute it, and
769 // notify mark-sweep that the range is no longer to be considered 'archive.'
770 MutexLocker x(Heap_lock);
771 for (size_t i = 0; i < count; i++) {
772 HeapWord* start_address = ranges[i].start();
773 HeapWord* last_address = ranges[i].last();
774
775 assert(reserved.contains(start_address) && reserved.contains(last_address),
776 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
777 p2i(start_address), p2i(last_address));
778 assert(start_address > prev_last_addr,
779 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
780 p2i(start_address), p2i(prev_last_addr));
781 size_used += ranges[i].byte_size();
782 prev_last_addr = last_address;
783
784 HeapRegion* start_region = _hrm.addr_to_region(start_address);
785 HeapRegion* last_region = _hrm.addr_to_region(last_address);
786
787 // Check for ranges that start in the same G1 region in which the previous
788 // range ended, and adjust the start address so we don't try to free
789 // the same region again. If the current range is entirely within that
790 // region, skip it.
791 if (start_region == prev_last_region) {
792 start_address = start_region->end();
793 if (start_address > last_address) {
794 continue;
795 }
796 start_region = _hrm.addr_to_region(start_address);
797 }
798 prev_last_region = last_region;
799
800 // After verifying that each region was marked as an archive region by
801 // alloc_archive_regions, set it free and empty and uncommit it.
802 HeapRegion* curr_region = start_region;
803 while (curr_region != NULL) {
804 guarantee(curr_region->is_archive(),
805 "Expected archive region at index %u", curr_region->hrm_index());
806 uint curr_index = curr_region->hrm_index();
807 _archive_set.remove(curr_region);
808 curr_region->set_free();
809 curr_region->set_top(curr_region->bottom());
810 if (curr_region != last_region) {
811 curr_region = _hrm.next_region_in_heap(curr_region);
812 } else {
813 curr_region = NULL;
814 }
815
816 _hrm.shrink_at(curr_index, 1);
817 shrink_count++;
818 }
819 }
820
821 if (shrink_count != 0) {
822 log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B",
823 HeapRegion::GrainWords * HeapWordSize * shrink_count);
824 // Explicit uncommit.
825 uncommit_regions(shrink_count);
826 }
827 decrease_used(size_used);
828 }
829
830 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
831 ResourceMark rm; // For retrieving the thread names in log messages.
832
833 // The structure of this method has a lot of similarities to
834 // attempt_allocation_slow(). The reason these two were not merged
835 // into a single one is that such a method would require several "if
836 // allocation is not humongous do this, otherwise do that"
837 // conditional paths which would obscure its flow. In fact, an early
838 // version of this code did use a unified method which was harder to
839 // follow and, as a result, it had subtle bugs that were hard to
840 // track down. So keeping these two methods separate allows each to
841 // be more readable. It will be good to keep these two in sync as
842 // much as possible.
843
844 assert_heap_not_locked_and_not_at_safepoint();
845 assert(is_humongous(word_size), "attempt_allocation_humongous() "
846 "should only be called for humongous allocations");
847
848 // Humongous objects can exhaust the heap quickly, so we should check if we
849 // need to start a marking cycle at each humongous object allocation. We do
850 // the check before we do the actual allocation. The reason for doing it
851 // before the allocation is that we avoid having to keep track of the newly
852 // allocated memory while we do a GC.
853 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
854 word_size)) {
855 collect(GCCause::_g1_humongous_allocation);
856 }
857
858 // We will loop until a) we manage to successfully perform the
859 // allocation or b) we successfully schedule a collection which
860 // fails to perform the allocation. b) is the only case when we'll
861 // return NULL.
862 HeapWord* result = NULL;
863 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
864 bool should_try_gc;
865 bool preventive_collection_required = false;
866 uint gc_count_before;
867
868
869 {
870 MutexLocker x(Heap_lock);
871
872 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
873 preventive_collection_required = policy()->preventive_collection_required((uint)size_in_regions);
874 if (!preventive_collection_required) {
875 // Given that humongous objects are not allocated in young
876 // regions, we'll first try to do the allocation without doing a
877 // collection hoping that there's enough space in the heap.
878 result = humongous_obj_allocate(word_size);
879 if (result != NULL) {
880 policy()->old_gen_alloc_tracker()->
881 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
882 return result;
883 }
884 }
885
886 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
887 // the GCLocker initiated GC has been performed and then retry. This includes
888 // the case when the GC Locker is not active but has not been performed.
889 should_try_gc = !GCLocker::needs_gc();
890 // Read the GC count while still holding the Heap_lock.
891 gc_count_before = total_collections();
892 }
893
894 if (should_try_gc) {
895 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
896 : GCCause::_g1_humongous_allocation;
897 bool succeeded;
898 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
899 if (result != NULL) {
900 assert(succeeded, "only way to get back a non-NULL result");
901 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
902 Thread::current()->name(), p2i(result));
903 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
904 policy()->old_gen_alloc_tracker()->
905 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
906 return result;
907 }
908
909 if (succeeded) {
910 // We successfully scheduled a collection which failed to allocate. No
911 // point in trying to allocate further. We'll just return NULL.
912 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
913 SIZE_FORMAT " words", Thread::current()->name(), word_size);
914 return NULL;
915 }
916 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
917 Thread::current()->name(), word_size);
918 } else {
919 // Failed to schedule a collection.
920 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
921 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
922 SIZE_FORMAT " words", Thread::current()->name(), word_size);
923 return NULL;
924 }
925 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
926 // The GCLocker is either active or the GCLocker initiated
927 // GC has not yet been performed. Stall until it is and
928 // then retry the allocation.
929 GCLocker::stall_until_clear();
930 gclocker_retry_count += 1;
931 }
932
933
934 // We can reach here if we were unsuccessful in scheduling a
935 // collection (because another thread beat us to it) or if we were
936 // stalled due to the GC locker. In either can we should retry the
937 // allocation attempt in case another thread successfully
938 // performed a collection and reclaimed enough space.
939 // Humongous object allocation always needs a lock, so we wait for the retry
940 // in the next iteration of the loop, unlike for the regular iteration case.
941 // Give a warning if we seem to be looping forever.
942
943 if ((QueuedAllocationWarningCount > 0) &&
944 (try_count % QueuedAllocationWarningCount == 0)) {
945 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
946 Thread::current()->name(), try_count, word_size);
947 }
948 }
949
950 ShouldNotReachHere();
951 return NULL;
952 }
953
954 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
955 bool expect_null_mutator_alloc_region) {
956 assert_at_safepoint_on_vm_thread();
957 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
958 "the current alloc region was unexpectedly found to be non-NULL");
959
960 if (!is_humongous(word_size)) {
961 return _allocator->attempt_allocation_locked(word_size);
962 } else {
963 HeapWord* result = humongous_obj_allocate(word_size);
964 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
965 collector_state()->set_initiate_conc_mark_if_possible(true);
966 }
967 return result;
968 }
969
970 ShouldNotReachHere();
971 }
972
973 class PostCompactionPrinterClosure: public HeapRegionClosure {
974 private:
975 G1HRPrinter* _hr_printer;
976 public:
977 bool do_heap_region(HeapRegion* hr) {
978 assert(!hr->is_young(), "not expecting to find young regions");
979 _hr_printer->post_compaction(hr);
980 return false;
981 }
982
983 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
984 : _hr_printer(hr_printer) { }
985 };
986
987 void G1CollectedHeap::print_heap_after_full_collection() {
988 // Post collection region logging.
989 // We should do this after we potentially resize the heap so
990 // that all the COMMIT / UNCOMMIT events are generated before
991 // the compaction events.
992 if (_hr_printer.is_active()) {
993 PostCompactionPrinterClosure cl(hr_printer());
994 heap_region_iterate(&cl);
995 }
996 }
997
998 bool G1CollectedHeap::abort_concurrent_cycle() {
999 // Disable discovery and empty the discovered lists
1000 // for the CM ref processor.
1001 _ref_processor_cm->disable_discovery();
1002 _ref_processor_cm->abandon_partial_discovery();
1003 _ref_processor_cm->verify_no_references_recorded();
1004
1005 // Abandon current iterations of concurrent marking and concurrent
1006 // refinement, if any are in progress.
1007 return concurrent_mark()->concurrent_cycle_abort();
1008 }
1009
1010 void G1CollectedHeap::prepare_heap_for_full_collection() {
1011 // Make sure we'll choose a new allocation region afterwards.
1012 _allocator->release_mutator_alloc_regions();
1013 _allocator->abandon_gc_alloc_regions();
1014
1015 // We may have added regions to the current incremental collection
1016 // set between the last GC or pause and now. We need to clear the
1017 // incremental collection set and then start rebuilding it afresh
1018 // after this full GC.
1019 abandon_collection_set(collection_set());
1020
1021 _hrm.remove_all_free_regions();
1022 }
1023
1024 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1025 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1026 assert_used_and_recalculate_used_equal(this);
1027 if (!VerifyBeforeGC) {
1028 return;
1029 }
1030 _verifier->verify_region_sets_optional();
1031 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1032 _verifier->verify_bitmap_clear(true /* above_tams_only */);
1033 }
1034
1035 void G1CollectedHeap::prepare_heap_for_mutators() {
1036 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1037 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1038 DEBUG_ONLY(MetaspaceUtils::verify();)
1039
1040 // Prepare heap for normal collections.
1041 assert(num_free_regions() == 0, "we should not have added any free regions");
1042 rebuild_region_sets(false /* free_list_only */);
1043 abort_refinement();
1044 resize_heap_if_necessary();
1045 uncommit_regions_if_necessary();
1046
1047 // Rebuild the code root lists for each region
1048 rebuild_code_roots();
1049
1050 // Purge code root memory
1051 purge_code_root_memory();
1052
1053 // Start a new incremental collection set for the next pause
1054 start_new_collection_set();
1055
1056 _allocator->init_mutator_alloc_regions();
1057
1058 // Post collection state updates.
1059 MetaspaceGC::compute_new_size();
1060 }
1061
1062 void G1CollectedHeap::abort_refinement() {
1063 if (G1HotCardCache::use_cache()) {
1064 _hot_card_cache->reset_hot_cache();
1065 }
1066
1067 // Discard all remembered set updates and reset refinement statistics.
1068 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1069 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1070 "DCQS should be empty");
1071 concurrent_refine()->get_and_reset_refinement_stats();
1072 }
1073
1074 void G1CollectedHeap::verify_after_full_collection() {
1075 if (!VerifyAfterGC) {
1076 return;
1077 }
1078 _hrm.verify_optional();
1079 _verifier->verify_region_sets_optional();
1080 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1081 _verifier->verify_bitmap_clear(false /* above_tams_only */);
1082
1083 // At this point there should be no regions in the
1084 // entire heap tagged as young.
1085 assert(check_young_list_empty(), "young list should be empty at this point");
1086
1087 // Note: since we've just done a full GC, concurrent
1088 // marking is no longer active. Therefore we need not
1089 // re-enable reference discovery for the CM ref processor.
1090 // That will be done at the start of the next marking cycle.
1091 // We also know that the STW processor should no longer
1092 // discover any new references.
1093 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1094 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1095 _ref_processor_stw->verify_no_references_recorded();
1096 _ref_processor_cm->verify_no_references_recorded();
1097 }
1098
1099 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1100 bool clear_all_soft_refs,
1101 bool do_maximal_compaction) {
1102 assert_at_safepoint_on_vm_thread();
1103
1104 if (GCLocker::check_active_before_gc()) {
1105 // Full GC was not completed.
1106 return false;
1107 }
1108
1109 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1110 soft_ref_policy()->should_clear_all_soft_refs();
1111
1112 G1FullGCMark gc_mark;
1113 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1114 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
1115
1116 collector.prepare_collection();
1117 collector.collect();
1118 collector.complete_collection();
1119
1120 // Full collection was successfully completed.
1121 return true;
1122 }
1123
1124 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1125 // Currently, there is no facility in the do_full_collection(bool) API to notify
1126 // the caller that the collection did not succeed (e.g., because it was locked
1127 // out by the GC locker). So, right now, we'll ignore the return value.
1128 // When clear_all_soft_refs is set we want to do a maximal compaction
1129 // not leaving any dead wood.
1130 bool do_maximal_compaction = clear_all_soft_refs;
1131 bool dummy = do_full_collection(true, /* explicit_gc */
1132 clear_all_soft_refs,
1133 do_maximal_compaction);
1134 }
1135
1136 bool G1CollectedHeap::upgrade_to_full_collection() {
1137 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1138 log_info(gc, ergo)("Attempting full compaction clearing soft references");
1139 bool success = do_full_collection(false /* explicit gc */,
1140 true /* clear_all_soft_refs */,
1141 false /* do_maximal_compaction */);
1142 // do_full_collection only fails if blocked by GC locker and that can't
1143 // be the case here since we only call this when already completed one gc.
1144 assert(success, "invariant");
1145 return success;
1146 }
1147
1148 void G1CollectedHeap::resize_heap_if_necessary() {
1149 assert_at_safepoint_on_vm_thread();
1150
1151 bool should_expand;
1152 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1153
1154 if (resize_amount == 0) {
1155 return;
1156 } else if (should_expand) {
1157 expand(resize_amount, _workers);
1158 } else {
1159 shrink(resize_amount);
1160 }
1161 }
1162
1163 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1164 bool do_gc,
1165 bool maximal_compaction,
1166 bool expect_null_mutator_alloc_region,
1167 bool* gc_succeeded) {
1168 *gc_succeeded = true;
1169 // Let's attempt the allocation first.
1170 HeapWord* result =
1171 attempt_allocation_at_safepoint(word_size,
1172 expect_null_mutator_alloc_region);
1173 if (result != NULL) {
1174 return result;
1175 }
1176
1177 // In a G1 heap, we're supposed to keep allocation from failing by
1178 // incremental pauses. Therefore, at least for now, we'll favor
1179 // expansion over collection. (This might change in the future if we can
1180 // do something smarter than full collection to satisfy a failed alloc.)
1181 result = expand_and_allocate(word_size);
1182 if (result != NULL) {
1183 return result;
1184 }
1185
1186 if (do_gc) {
1187 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1188 // Expansion didn't work, we'll try to do a Full GC.
1189 // If maximal_compaction is set we clear all soft references and don't
1190 // allow any dead wood to be left on the heap.
1191 if (maximal_compaction) {
1192 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
1193 } else {
1194 log_info(gc, ergo)("Attempting full compaction");
1195 }
1196 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1197 maximal_compaction /* clear_all_soft_refs */ ,
1198 maximal_compaction /* do_maximal_compaction */);
1199 }
1200
1201 return NULL;
1202 }
1203
1204 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1205 bool* succeeded) {
1206 assert_at_safepoint_on_vm_thread();
1207
1208 // Attempts to allocate followed by Full GC.
1209 HeapWord* result =
1210 satisfy_failed_allocation_helper(word_size,
1211 true, /* do_gc */
1212 false, /* maximum_collection */
1213 false, /* expect_null_mutator_alloc_region */
1214 succeeded);
1215
1216 if (result != NULL || !*succeeded) {
1217 return result;
1218 }
1219
1220 // Attempts to allocate followed by Full GC that will collect all soft references.
1221 result = satisfy_failed_allocation_helper(word_size,
1222 true, /* do_gc */
1223 true, /* maximum_collection */
1224 true, /* expect_null_mutator_alloc_region */
1225 succeeded);
1226
1227 if (result != NULL || !*succeeded) {
1228 return result;
1229 }
1230
1231 // Attempts to allocate, no GC
1232 result = satisfy_failed_allocation_helper(word_size,
1233 false, /* do_gc */
1234 false, /* maximum_collection */
1235 true, /* expect_null_mutator_alloc_region */
1236 succeeded);
1237
1238 if (result != NULL) {
1239 return result;
1240 }
1241
1242 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1243 "Flag should have been handled and cleared prior to this point");
1244
1245 // What else? We might try synchronous finalization later. If the total
1246 // space available is large enough for the allocation, then a more
1247 // complete compaction phase than we've tried so far might be
1248 // appropriate.
1249 return NULL;
1250 }
1251
1252 // Attempting to expand the heap sufficiently
1253 // to support an allocation of the given "word_size". If
1254 // successful, perform the allocation and return the address of the
1255 // allocated block, or else "NULL".
1256
1257 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1258 assert_at_safepoint_on_vm_thread();
1259
1260 _verifier->verify_region_sets_optional();
1261
1262 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1263 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1264 word_size * HeapWordSize);
1265
1266
1267 if (expand(expand_bytes, _workers)) {
1268 _hrm.verify_optional();
1269 _verifier->verify_region_sets_optional();
1270 return attempt_allocation_at_safepoint(word_size,
1271 false /* expect_null_mutator_alloc_region */);
1272 }
1273 return NULL;
1274 }
1275
1276 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1277 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1278 aligned_expand_bytes = align_up(aligned_expand_bytes,
1279 HeapRegion::GrainBytes);
1280
1281 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1282 expand_bytes, aligned_expand_bytes);
1283
1284 if (is_maximal_no_gc()) {
1285 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1286 return false;
1287 }
1288
1289 double expand_heap_start_time_sec = os::elapsedTime();
1290 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1291 assert(regions_to_expand > 0, "Must expand by at least one region");
1292
1293 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1294 if (expand_time_ms != NULL) {
1295 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1296 }
1297
1298 if (expanded_by > 0) {
1299 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1300 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1301 policy()->record_new_heap_size(num_regions());
1302 } else {
1303 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1304
1305 // The expansion of the virtual storage space was unsuccessful.
1306 // Let's see if it was because we ran out of swap.
1307 if (G1ExitOnExpansionFailure &&
1308 _hrm.available() >= regions_to_expand) {
1309 // We had head room...
1310 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1311 }
1312 }
1313 return expanded_by > 0;
1314 }
1315
1316 bool G1CollectedHeap::expand_single_region(uint node_index) {
1317 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1318
1319 if (expanded_by == 0) {
1320 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1321 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1322 return false;
1323 }
1324
1325 policy()->record_new_heap_size(num_regions());
1326 return true;
1327 }
1328
1329 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1330 size_t aligned_shrink_bytes =
1331 ReservedSpace::page_align_size_down(shrink_bytes);
1332 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1333 HeapRegion::GrainBytes);
1334 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1335
1336 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1337 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1338
1339 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B actual amount shrunk: " SIZE_FORMAT "B",
1340 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1341 if (num_regions_removed > 0) {
1342 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1343 policy()->record_new_heap_size(num_regions());
1344 } else {
1345 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1346 }
1347 }
1348
1349 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1350 _verifier->verify_region_sets_optional();
1351
1352 // We should only reach here at the end of a Full GC or during Remark which
1353 // means we should not not be holding to any GC alloc regions. The method
1354 // below will make sure of that and do any remaining clean up.
1355 _allocator->abandon_gc_alloc_regions();
1356
1357 // Instead of tearing down / rebuilding the free lists here, we
1358 // could instead use the remove_all_pending() method on free_list to
1359 // remove only the ones that we need to remove.
1360 _hrm.remove_all_free_regions();
1361 shrink_helper(shrink_bytes);
1362 rebuild_region_sets(true /* free_list_only */);
1363
1364 _hrm.verify_optional();
1365 _verifier->verify_region_sets_optional();
1366 }
1367
1368 class OldRegionSetChecker : public HeapRegionSetChecker {
1369 public:
1370 void check_mt_safety() {
1371 // Master Old Set MT safety protocol:
1372 // (a) If we're at a safepoint, operations on the master old set
1373 // should be invoked:
1374 // - by the VM thread (which will serialize them), or
1375 // - by the GC workers while holding the FreeList_lock, if we're
1376 // at a safepoint for an evacuation pause (this lock is taken
1377 // anyway when an GC alloc region is retired so that a new one
1378 // is allocated from the free list), or
1379 // - by the GC workers while holding the OldSets_lock, if we're at a
1380 // safepoint for a cleanup pause.
1381 // (b) If we're not at a safepoint, operations on the master old set
1382 // should be invoked while holding the Heap_lock.
1383
1384 if (SafepointSynchronize::is_at_safepoint()) {
1385 guarantee(Thread::current()->is_VM_thread() ||
1386 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1387 "master old set MT safety protocol at a safepoint");
1388 } else {
1389 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1390 }
1391 }
1392 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1393 const char* get_description() { return "Old Regions"; }
1394 };
1395
1396 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1397 public:
1398 void check_mt_safety() {
1399 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1400 "May only change archive regions during initialization or safepoint.");
1401 }
1402 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1403 const char* get_description() { return "Archive Regions"; }
1404 };
1405
1406 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1407 public:
1408 void check_mt_safety() {
1409 // Humongous Set MT safety protocol:
1410 // (a) If we're at a safepoint, operations on the master humongous
1411 // set should be invoked by either the VM thread (which will
1412 // serialize them) or by the GC workers while holding the
1413 // OldSets_lock.
1414 // (b) If we're not at a safepoint, operations on the master
1415 // humongous set should be invoked while holding the Heap_lock.
1416
1417 if (SafepointSynchronize::is_at_safepoint()) {
1418 guarantee(Thread::current()->is_VM_thread() ||
1419 OldSets_lock->owned_by_self(),
1420 "master humongous set MT safety protocol at a safepoint");
1421 } else {
1422 guarantee(Heap_lock->owned_by_self(),
1423 "master humongous set MT safety protocol outside a safepoint");
1424 }
1425 }
1426 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1427 const char* get_description() { return "Humongous Regions"; }
1428 };
1429
1430 G1CollectedHeap::G1CollectedHeap() :
1431 CollectedHeap(),
1432 _service_thread(NULL),
1433 _periodic_gc_task(NULL),
1434 _free_segmented_array_memory_task(NULL),
1435 _workers(NULL),
1436 _card_table(NULL),
1437 _collection_pause_end(Ticks::now()),
1438 _soft_ref_policy(),
1439 _old_set("Old Region Set", new OldRegionSetChecker()),
1440 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1441 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1442 _bot(NULL),
1443 _listener(),
1444 _numa(G1NUMA::create()),
1445 _hrm(),
1446 _allocator(NULL),
1447 _evac_failure_injector(),
1448 _verifier(NULL),
1449 _summary_bytes_used(0),
1450 _bytes_used_during_gc(0),
1451 _archive_allocator(nullptr),
1452 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1453 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1454 _monitoring_support(nullptr),
1455 _num_humongous_objects(0),
1456 _num_humongous_reclaim_candidates(0),
1457 _hr_printer(),
1458 _collector_state(),
1459 _old_marking_cycles_started(0),
1460 _old_marking_cycles_completed(0),
1461 _eden(),
1462 _survivor(),
1463 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1464 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1465 _policy(new G1Policy(_gc_timer_stw)),
1466 _heap_sizing_policy(NULL),
1467 _collection_set(this, _policy),
1468 _hot_card_cache(NULL),
1469 _rem_set(NULL),
1470 _card_set_config(),
1471 _cm(NULL),
1472 _cm_thread(NULL),
1473 _cr(NULL),
1474 _task_queues(NULL),
1475 _ref_processor_stw(NULL),
1476 _is_alive_closure_stw(this),
1477 _is_subject_to_discovery_stw(this),
1478 _ref_processor_cm(NULL),
1479 _is_alive_closure_cm(this),
1480 _is_subject_to_discovery_cm(this),
1481 _region_attr() {
1482
1483 _verifier = new G1HeapVerifier(this);
1484
1485 _allocator = new G1Allocator(this);
1486
1487 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1488
1489 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1490
1491 // Override the default _filler_array_max_size so that no humongous filler
1492 // objects are created.
1493 _filler_array_max_size = _humongous_object_threshold_in_words;
1494
1495 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1496 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1497
1498 uint n_queues = ParallelGCThreads;
1499 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1500
1501 for (uint i = 0; i < n_queues; i++) {
1502 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1503 _task_queues->register_queue(i, q);
1504 }
1505
1506 _gc_tracer_stw->initialize();
1507
1508 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1509 }
1510
1511 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1512 size_t size,
1513 size_t translation_factor) {
1514 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1515 // Allocate a new reserved space, preferring to use large pages.
1516 ReservedSpace rs(size, preferred_page_size);
1517 size_t page_size = rs.page_size();
1518 G1RegionToSpaceMapper* result =
1519 G1RegionToSpaceMapper::create_mapper(rs,
1520 size,
1521 page_size,
1522 HeapRegion::GrainBytes,
1523 translation_factor,
1524 mtGC);
1525
1526 os::trace_page_sizes_for_requested_size(description,
1527 size,
1528 page_size,
1529 preferred_page_size,
1530 rs.base(),
1531 rs.size());
1532
1533 return result;
1534 }
1535
1536 jint G1CollectedHeap::initialize_concurrent_refinement() {
1537 jint ecode = JNI_OK;
1538 _cr = G1ConcurrentRefine::create(&ecode);
1539 return ecode;
1540 }
1541
1542 jint G1CollectedHeap::initialize_service_thread() {
1543 _service_thread = new G1ServiceThread();
1544 if (_service_thread->osthread() == NULL) {
1545 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1546 return JNI_ENOMEM;
1547 }
1548 return JNI_OK;
1549 }
1550
1551 jint G1CollectedHeap::initialize() {
1552
1553 // Necessary to satisfy locking discipline assertions.
1554
1555 MutexLocker x(Heap_lock);
1556
1557 // While there are no constraints in the GC code that HeapWordSize
1558 // be any particular value, there are multiple other areas in the
1559 // system which believe this to be true (e.g. oop->object_size in some
1560 // cases incorrectly returns the size in wordSize units rather than
1561 // HeapWordSize).
1562 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1563
1564 size_t init_byte_size = InitialHeapSize;
1565 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1566
1567 // Ensure that the sizes are properly aligned.
1568 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1569 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1570 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1571
1572 // Reserve the maximum.
1573
1574 // When compressed oops are enabled, the preferred heap base
1575 // is calculated by subtracting the requested size from the
1576 // 32Gb boundary and using the result as the base address for
1577 // heap reservation. If the requested size is not aligned to
1578 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1579 // into the ReservedHeapSpace constructor) then the actual
1580 // base of the reserved heap may end up differing from the
1581 // address that was requested (i.e. the preferred heap base).
1582 // If this happens then we could end up using a non-optimal
1583 // compressed oops mode.
1584
1585 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1586 HeapAlignment);
1587
1588 initialize_reserved_region(heap_rs);
1589
1590 _forwarding = new SlidingForwarding(heap_rs.region(), HeapRegion::LogOfHRGrainBytes - LogHeapWordSize);
1591
1592 // Create the barrier set for the entire reserved region.
1593 G1CardTable* ct = new G1CardTable(heap_rs.region());
1594 ct->initialize();
1595 G1BarrierSet* bs = new G1BarrierSet(ct);
1596 bs->initialize();
1597 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1598 BarrierSet::set_barrier_set(bs);
1599 _card_table = ct;
1600
1601 {
1602 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1603 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1604 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1605 }
1606
1607 // Create the hot card cache.
1608 _hot_card_cache = new G1HotCardCache(this);
1609
1610 // Create space mappers.
1611 size_t page_size = heap_rs.page_size();
1612 G1RegionToSpaceMapper* heap_storage =
1613 G1RegionToSpaceMapper::create_mapper(heap_rs,
1614 heap_rs.size(),
1615 page_size,
1616 HeapRegion::GrainBytes,
1617 1,
1618 mtJavaHeap);
1619 if(heap_storage == NULL) {
1620 vm_shutdown_during_initialization("Could not initialize G1 heap");
1621 return JNI_ERR;
1622 }
1623
1624 os::trace_page_sizes("Heap",
1625 MinHeapSize,
1626 reserved_byte_size,
1627 page_size,
1628 heap_rs.base(),
1629 heap_rs.size());
1630 heap_storage->set_mapping_changed_listener(&_listener);
1631
1632 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmap.
1633 G1RegionToSpaceMapper* bot_storage =
1634 create_aux_memory_mapper("Block Offset Table",
1635 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1636 G1BlockOffsetTable::heap_map_factor());
1637
1638 G1RegionToSpaceMapper* cardtable_storage =
1639 create_aux_memory_mapper("Card Table",
1640 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1641 G1CardTable::heap_map_factor());
1642
1643 G1RegionToSpaceMapper* card_counts_storage =
1644 create_aux_memory_mapper("Card Counts Table",
1645 G1CardCounts::compute_size(heap_rs.size() / HeapWordSize),
1646 G1CardCounts::heap_map_factor());
1647
1648 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1649 G1RegionToSpaceMapper* bitmap_storage =
1650 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1651
1652 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1653 _card_table->initialize(cardtable_storage);
1654
1655 // Do later initialization work for concurrent refinement.
1656 _hot_card_cache->initialize(card_counts_storage);
1657
1658 // 6843694 - ensure that the maximum region index can fit
1659 // in the remembered set structures.
1660 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1661 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1662
1663 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1664 // start within the first card.
1665 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1666 G1FromCardCache::initialize(max_reserved_regions());
1667 // Also create a G1 rem set.
1668 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1669 _rem_set->initialize(max_reserved_regions());
1670
1671 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1672 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1673 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1674 "too many cards per region");
1675
1676 HeapRegionRemSet::initialize(_reserved);
1677
1678 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1679
1680 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1681
1682 {
1683 size_t granularity = HeapRegion::GrainBytes;
1684
1685 _region_attr.initialize(reserved(), granularity);
1686 }
1687
1688 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1689 if (_workers == NULL) {
1690 return JNI_ENOMEM;
1691 }
1692 _workers->initialize_workers();
1693
1694 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1695
1696 // Create the G1ConcurrentMark data structure and thread.
1697 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1698 _cm = new G1ConcurrentMark(this, bitmap_storage);
1699 _cm_thread = _cm->cm_thread();
1700
1701 // Now expand into the initial heap size.
1702 if (!expand(init_byte_size, _workers)) {
1703 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1704 return JNI_ENOMEM;
1705 }
1706
1707 // Perform any initialization actions delegated to the policy.
1708 policy()->init(this, &_collection_set);
1709
1710 jint ecode = initialize_concurrent_refinement();
1711 if (ecode != JNI_OK) {
1712 return ecode;
1713 }
1714
1715 ecode = initialize_service_thread();
1716 if (ecode != JNI_OK) {
1717 return ecode;
1718 }
1719
1720 // Initialize and schedule sampling task on service thread.
1721 _rem_set->initialize_sampling_task(service_thread());
1722
1723 // Create and schedule the periodic gc task on the service thread.
1724 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1725 _service_thread->register_task(_periodic_gc_task);
1726
1727 _free_segmented_array_memory_task = new G1SegmentedArrayFreeMemoryTask("Card Set Free Memory Task");
1728 _service_thread->register_task(_free_segmented_array_memory_task);
1729
1730 // Here we allocate the dummy HeapRegion that is required by the
1731 // G1AllocRegion class.
1732 HeapRegion* dummy_region = _hrm.get_dummy_region();
1733
1734 // We'll re-use the same region whether the alloc region will
1735 // require BOT updates or not and, if it doesn't, then a non-young
1736 // region will complain that it cannot support allocations without
1737 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1738 dummy_region->set_eden();
1739 // Make sure it's full.
1740 dummy_region->set_top(dummy_region->end());
1741 G1AllocRegion::setup(this, dummy_region);
1742
1743 _allocator->init_mutator_alloc_regions();
1744
1745 // Do create of the monitoring and management support so that
1746 // values in the heap have been properly initialized.
1747 _monitoring_support = new G1MonitoringSupport(this);
1748
1749 _collection_set.initialize(max_reserved_regions());
1750
1751 evac_failure_injector()->reset();
1752
1753 G1InitLogger::print();
1754
1755 return JNI_OK;
1756 }
1757
1758 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1759 return _cm_thread->should_terminate();
1760 }
1761
1762 void G1CollectedHeap::stop() {
1763 // Stop all concurrent threads. We do this to make sure these threads
1764 // do not continue to execute and access resources (e.g. logging)
1765 // that are destroyed during shutdown.
1766 _cr->stop();
1767 _service_thread->stop();
1768 _cm_thread->stop();
1769 }
1770
1771 void G1CollectedHeap::safepoint_synchronize_begin() {
1772 SuspendibleThreadSet::synchronize();
1773 }
1774
1775 void G1CollectedHeap::safepoint_synchronize_end() {
1776 SuspendibleThreadSet::desynchronize();
1777 }
1778
1779 void G1CollectedHeap::post_initialize() {
1780 CollectedHeap::post_initialize();
1781 ref_processing_init();
1782 }
1783
1784 void G1CollectedHeap::ref_processing_init() {
1785 // Reference processing in G1 currently works as follows:
1786 //
1787 // * There are two reference processor instances. One is
1788 // used to record and process discovered references
1789 // during concurrent marking; the other is used to
1790 // record and process references during STW pauses
1791 // (both full and incremental).
1792 // * Both ref processors need to 'span' the entire heap as
1793 // the regions in the collection set may be dotted around.
1794 //
1795 // * For the concurrent marking ref processor:
1796 // * Reference discovery is enabled at concurrent start.
1797 // * Reference discovery is disabled and the discovered
1798 // references processed etc during remarking.
1799 // * Reference discovery is MT (see below).
1800 // * Reference discovery requires a barrier (see below).
1801 // * Reference processing may or may not be MT
1802 // (depending on the value of ParallelRefProcEnabled
1803 // and ParallelGCThreads).
1804 // * A full GC disables reference discovery by the CM
1805 // ref processor and abandons any entries on it's
1806 // discovered lists.
1807 //
1808 // * For the STW processor:
1809 // * Non MT discovery is enabled at the start of a full GC.
1810 // * Processing and enqueueing during a full GC is non-MT.
1811 // * During a full GC, references are processed after marking.
1812 //
1813 // * Discovery (may or may not be MT) is enabled at the start
1814 // of an incremental evacuation pause.
1815 // * References are processed near the end of a STW evacuation pause.
1816 // * For both types of GC:
1817 // * Discovery is atomic - i.e. not concurrent.
1818 // * Reference discovery will not need a barrier.
1819
1820 // Concurrent Mark ref processor
1821 _ref_processor_cm =
1822 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1823 ParallelGCThreads, // degree of mt processing
1824 // We discover with the gc worker threads during Remark, so both
1825 // thread counts must be considered for discovery.
1826 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1827 true, // Reference discovery is concurrent
1828 &_is_alive_closure_cm); // is alive closure
1829
1830 // STW ref processor
1831 _ref_processor_stw =
1832 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1833 ParallelGCThreads, // degree of mt processing
1834 ParallelGCThreads, // degree of mt discovery
1835 false, // Reference discovery is not concurrent
1836 &_is_alive_closure_stw); // is alive closure
1837 }
1838
1839 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1840 return &_soft_ref_policy;
1841 }
1842
1843 size_t G1CollectedHeap::capacity() const {
1844 return _hrm.length() * HeapRegion::GrainBytes;
1845 }
1846
1847 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1848 return _hrm.total_free_bytes();
1849 }
1850
1851 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1852 _hot_card_cache->drain(cl, worker_id);
1853 }
1854
1855 // Computes the sum of the storage used by the various regions.
1856 size_t G1CollectedHeap::used() const {
1857 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1858 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
1859 return result;
1860 }
1861
1862 size_t G1CollectedHeap::used_unlocked() const {
1863 return _summary_bytes_used;
1864 }
1865
1866 class SumUsedClosure: public HeapRegionClosure {
1867 size_t _used;
1868 public:
1869 SumUsedClosure() : _used(0) {}
1870 bool do_heap_region(HeapRegion* r) {
1871 _used += r->used();
1872 return false;
1873 }
1874 size_t result() { return _used; }
1875 };
1876
1877 size_t G1CollectedHeap::recalculate_used() const {
1878 SumUsedClosure blk;
1879 heap_region_iterate(&blk);
1880 return blk.result();
1881 }
1882
1883 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1884 switch (cause) {
1885 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1886 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1887 case GCCause::_wb_conc_mark: return true;
1888 default : return false;
1889 }
1890 }
1891
1892 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1893 switch (cause) {
1894 case GCCause::_g1_humongous_allocation: return true;
1895 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1896 case GCCause::_wb_breakpoint: return true;
1897 case GCCause::_codecache_GC_aggressive: return true;
1898 case GCCause::_codecache_GC_threshold: return true;
1899 default: return is_user_requested_concurrent_full_gc(cause);
1900 }
1901 }
1902
1903 #ifndef PRODUCT
1904 void G1CollectedHeap::allocate_dummy_regions() {
1905 // Let's fill up most of the region
1906 size_t word_size = HeapRegion::GrainWords - 1024;
1907 // And as a result the region we'll allocate will be humongous.
1908 guarantee(is_humongous(word_size), "sanity");
1909
1910 // _filler_array_max_size is set to humongous object threshold
1911 // but temporarily change it to use CollectedHeap::fill_with_object().
1912 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1913
1914 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1915 // Let's use the existing mechanism for the allocation
1916 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1917 if (dummy_obj != NULL) {
1918 MemRegion mr(dummy_obj, word_size);
1919 CollectedHeap::fill_with_object(mr);
1920 } else {
1921 // If we can't allocate once, we probably cannot allocate
1922 // again. Let's get out of the loop.
1923 break;
1924 }
1925 }
1926 }
1927 #endif // !PRODUCT
1928
1929 void G1CollectedHeap::increment_old_marking_cycles_started() {
1930 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1931 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1932 "Wrong marking cycle count (started: %d, completed: %d)",
1933 _old_marking_cycles_started, _old_marking_cycles_completed);
1934
1935 _old_marking_cycles_started++;
1936 }
1937
1938 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1939 bool whole_heap_examined) {
1940 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1941
1942 // We assume that if concurrent == true, then the caller is a
1943 // concurrent thread that was joined the Suspendible Thread
1944 // Set. If there's ever a cheap way to check this, we should add an
1945 // assert here.
1946
1947 // Given that this method is called at the end of a Full GC or of a
1948 // concurrent cycle, and those can be nested (i.e., a Full GC can
1949 // interrupt a concurrent cycle), the number of full collections
1950 // completed should be either one (in the case where there was no
1951 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1952 // behind the number of full collections started.
1953
1954 // This is the case for the inner caller, i.e. a Full GC.
1955 assert(concurrent ||
1956 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1957 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1958 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1959 "is inconsistent with _old_marking_cycles_completed = %u",
1960 _old_marking_cycles_started, _old_marking_cycles_completed);
1961
1962 // This is the case for the outer caller, i.e. the concurrent cycle.
1963 assert(!concurrent ||
1964 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1965 "for outer caller (concurrent cycle): "
1966 "_old_marking_cycles_started = %u "
1967 "is inconsistent with _old_marking_cycles_completed = %u",
1968 _old_marking_cycles_started, _old_marking_cycles_completed);
1969
1970 _old_marking_cycles_completed += 1;
1971 if (whole_heap_examined) {
1972 // Signal that we have completed a visit to all live objects.
1973 record_whole_heap_examined_timestamp();
1974 }
1975
1976 // We need to clear the "in_progress" flag in the CM thread before
1977 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1978 // is set) so that if a waiter requests another System.gc() it doesn't
1979 // incorrectly see that a marking cycle is still in progress.
1980 if (concurrent) {
1981 _cm_thread->set_idle();
1982 }
1983
1984 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1985 // for a full GC to finish that their wait is over.
1986 ml.notify_all();
1987 }
1988
1989 // Helper for collect().
1990 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1991 MutexLocker ml(Heap_lock);
1992 return G1GCCounters(g1h);
1993 }
1994
1995 void G1CollectedHeap::collect(GCCause::Cause cause) {
1996 try_collect(cause, collection_counters(this));
1997 }
1998
1999 // Return true if (x < y) with allowance for wraparound.
2000 static bool gc_counter_less_than(uint x, uint y) {
2001 return (x - y) > (UINT_MAX/2);
2002 }
2003
2004 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2005 // Macro so msg printing is format-checked.
2006 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2007 do { \
2008 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2009 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2010 ResourceMark rm; /* For thread name. */ \
2011 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2012 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2013 Thread::current()->name(), \
2014 GCCause::to_string(cause)); \
2015 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2016 } \
2017 } while (0)
2018
2019 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2020 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2021
2022 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2023 uint gc_counter,
2024 uint old_marking_started_before) {
2025 assert_heap_not_locked();
2026 assert(should_do_concurrent_full_gc(cause),
2027 "Non-concurrent cause %s", GCCause::to_string(cause));
2028
2029 for (uint i = 1; true; ++i) {
2030 // Try to schedule concurrent start evacuation pause that will
2031 // start a concurrent cycle.
2032 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2033 VM_G1TryInitiateConcMark op(gc_counter,
2034 cause,
2035 policy()->max_pause_time_ms());
2036 VMThread::execute(&op);
2037
2038 // Request is trivially finished.
2039 if (cause == GCCause::_g1_periodic_collection) {
2040 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2041 return op.gc_succeeded();
2042 }
2043
2044 // If VMOp skipped initiating concurrent marking cycle because
2045 // we're terminating, then we're done.
2046 if (op.terminating()) {
2047 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2048 return false;
2049 }
2050
2051 // Lock to get consistent set of values.
2052 uint old_marking_started_after;
2053 uint old_marking_completed_after;
2054 {
2055 MutexLocker ml(Heap_lock);
2056 // Update gc_counter for retrying VMOp if needed. Captured here to be
2057 // consistent with the values we use below for termination tests. If
2058 // a retry is needed after a possible wait, and another collection
2059 // occurs in the meantime, it will cause our retry to be skipped and
2060 // we'll recheck for termination with updated conditions from that
2061 // more recent collection. That's what we want, rather than having
2062 // our retry possibly perform an unnecessary collection.
2063 gc_counter = total_collections();
2064 old_marking_started_after = _old_marking_cycles_started;
2065 old_marking_completed_after = _old_marking_cycles_completed;
2066 }
2067
2068 if (cause == GCCause::_wb_breakpoint) {
2069 if (op.gc_succeeded()) {
2070 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2071 return true;
2072 }
2073 // When _wb_breakpoint there can't be another cycle or deferred.
2074 assert(!op.cycle_already_in_progress(), "invariant");
2075 assert(!op.whitebox_attached(), "invariant");
2076 // Concurrent cycle attempt might have been cancelled by some other
2077 // collection, so retry. Unlike other cases below, we want to retry
2078 // even if cancelled by a STW full collection, because we really want
2079 // to start a concurrent cycle.
2080 if (old_marking_started_before != old_marking_started_after) {
2081 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2082 old_marking_started_before = old_marking_started_after;
2083 }
2084 } else if (!GCCause::is_user_requested_gc(cause)) {
2085 // For an "automatic" (not user-requested) collection, we just need to
2086 // ensure that progress is made.
2087 //
2088 // Request is finished if any of
2089 // (1) the VMOp successfully performed a GC,
2090 // (2) a concurrent cycle was already in progress,
2091 // (3) whitebox is controlling concurrent cycles,
2092 // (4) a new cycle was started (by this thread or some other), or
2093 // (5) a Full GC was performed.
2094 // Cases (4) and (5) are detected together by a change to
2095 // _old_marking_cycles_started.
2096 //
2097 // Note that (1) does not imply (4). If we're still in the mixed
2098 // phase of an earlier concurrent collection, the request to make the
2099 // collection a concurrent start won't be honored. If we don't check for
2100 // both conditions we'll spin doing back-to-back collections.
2101 if (op.gc_succeeded() ||
2102 op.cycle_already_in_progress() ||
2103 op.whitebox_attached() ||
2104 (old_marking_started_before != old_marking_started_after)) {
2105 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2106 return true;
2107 }
2108 } else { // User-requested GC.
2109 // For a user-requested collection, we want to ensure that a complete
2110 // full collection has been performed before returning, but without
2111 // waiting for more than needed.
2112
2113 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2114 // new cycle was started. That's good, because it's not clear what we
2115 // should do otherwise. Trying again just does back to back GCs.
2116 // Can't wait for someone else to start a cycle. And returning fails
2117 // to meet the goal of ensuring a full collection was performed.
2118 assert(!op.gc_succeeded() ||
2119 (old_marking_started_before != old_marking_started_after),
2120 "invariant: succeeded %s, started before %u, started after %u",
2121 BOOL_TO_STR(op.gc_succeeded()),
2122 old_marking_started_before, old_marking_started_after);
2123
2124 // Request is finished if a full collection (concurrent or stw)
2125 // was started after this request and has completed, e.g.
2126 // started_before < completed_after.
2127 if (gc_counter_less_than(old_marking_started_before,
2128 old_marking_completed_after)) {
2129 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2130 return true;
2131 }
2132
2133 if (old_marking_started_after != old_marking_completed_after) {
2134 // If there is an in-progress cycle (possibly started by us), then
2135 // wait for that cycle to complete, e.g.
2136 // while completed_now < started_after.
2137 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2138 MonitorLocker ml(G1OldGCCount_lock);
2139 while (gc_counter_less_than(_old_marking_cycles_completed,
2140 old_marking_started_after)) {
2141 ml.wait();
2142 }
2143 // Request is finished if the collection we just waited for was
2144 // started after this request.
2145 if (old_marking_started_before != old_marking_started_after) {
2146 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2147 return true;
2148 }
2149 }
2150
2151 // If VMOp was successful then it started a new cycle that the above
2152 // wait &etc should have recognized as finishing this request. This
2153 // differs from a non-user-request, where gc_succeeded does not imply
2154 // a new cycle was started.
2155 assert(!op.gc_succeeded(), "invariant");
2156
2157 if (op.cycle_already_in_progress()) {
2158 // If VMOp failed because a cycle was already in progress, it
2159 // is now complete. But it didn't finish this user-requested
2160 // GC, so try again.
2161 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2162 continue;
2163 } else if (op.whitebox_attached()) {
2164 // If WhiteBox wants control, wait for notification of a state
2165 // change in the controller, then try again. Don't wait for
2166 // release of control, since collections may complete while in
2167 // control. Note: This won't recognize a STW full collection
2168 // while waiting; we can't wait on multiple monitors.
2169 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2170 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2171 if (ConcurrentGCBreakpoints::is_controlled()) {
2172 ml.wait();
2173 }
2174 continue;
2175 }
2176 }
2177
2178 // Collection failed and should be retried.
2179 assert(op.transient_failure(), "invariant");
2180
2181 if (GCLocker::is_active_and_needs_gc()) {
2182 // If GCLocker is active, wait until clear before retrying.
2183 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2184 GCLocker::stall_until_clear();
2185 }
2186
2187 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2188 }
2189 }
2190
2191 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
2192 const G1GCCounters& counters_before) {
2193 if (should_do_concurrent_full_gc(cause)) {
2194 return try_collect_concurrently(cause,
2195 counters_before.total_collections(),
2196 counters_before.old_marking_cycles_started());
2197 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
2198 // Indicate failure to be consistent with VMOp failure due to
2199 // another collection slipping in after our gc_count but before
2200 // our request is processed.
2201 return false;
2202 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2203 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2204
2205 // Schedule a standard evacuation pause. We're setting word_size
2206 // to 0 which means that we are not requesting a post-GC allocation.
2207 VM_G1CollectForAllocation op(0, /* word_size */
2208 counters_before.total_collections(),
2209 cause,
2210 policy()->max_pause_time_ms());
2211 VMThread::execute(&op);
2212 return op.gc_succeeded();
2213 } else {
2214 // Schedule a Full GC.
2215 VM_G1CollectFull op(counters_before.total_collections(),
2216 counters_before.total_full_collections(),
2217 cause);
2218 VMThread::execute(&op);
2219 return op.gc_succeeded();
2220 }
2221 }
2222
2223 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
2224 GCCauseSetter x(this, gc_cause);
2225
2226 // At this point we are supposed to start a concurrent cycle. We
2227 // will do so if one is not already in progress.
2228 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
2229 if (should_start) {
2230 double pause_target = policy()->max_pause_time_ms();
2231 do_collection_pause_at_safepoint(pause_target);
2232 }
2233 }
2234
2235 bool G1CollectedHeap::is_in(const void* p) const {
2236 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
2237 }
2238
2239 // Iteration functions.
2240
2241 // Iterates an ObjectClosure over all objects within a HeapRegion.
2242
2243 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2244 ObjectClosure* _cl;
2245 public:
2246 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2247 bool do_heap_region(HeapRegion* r) {
2248 if (!r->is_continues_humongous()) {
2249 r->object_iterate(_cl);
2250 }
2251 return false;
2252 }
2253 };
2254
2255 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2256 IterateObjectClosureRegionClosure blk(cl);
2257 heap_region_iterate(&blk);
2258 }
2259
2260 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2261 private:
2262 G1CollectedHeap* _heap;
2263 HeapRegionClaimer _claimer;
2264
2265 public:
2266 G1ParallelObjectIterator(uint thread_num) :
2267 _heap(G1CollectedHeap::heap()),
2268 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2269
2270 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2271 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2272 }
2273 };
2274
2275 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2276 return new G1ParallelObjectIterator(thread_num);
2277 }
2278
2279 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2280 IterateObjectClosureRegionClosure blk(cl);
2281 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2282 }
2283
2284 void G1CollectedHeap::keep_alive(oop obj) {
2285 G1BarrierSet::enqueue_preloaded(obj);
2286 }
2287
2288 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2289 _hrm.iterate(cl);
2290 }
2291
2292 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2293 _hrm.iterate(cl);
2294 }
2295
2296 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2297 HeapRegionClaimer *hrclaimer,
2298 uint worker_id) const {
2299 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2300 }
2301
2302 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2303 HeapRegionClaimer *hrclaimer) const {
2304 _hrm.par_iterate(cl, hrclaimer, 0);
2305 }
2306
2307 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2308 _collection_set.iterate(cl);
2309 }
2310
2311 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2312 HeapRegionClaimer* hr_claimer,
2313 uint worker_id) {
2314 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2315 }
2316
2317 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2318 HeapRegionClaimer* hr_claimer,
2319 uint worker_id) {
2320 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2321 }
2322
2323 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2324 HeapRegionClaimer* hr_claimer,
2325 const uint regions[],
2326 size_t length,
2327 uint worker_id) const {
2328 assert_at_safepoint();
2329 if (length == 0) {
2330 return;
2331 }
2332 uint total_workers = workers()->active_workers();
2333
2334 size_t start_pos = (worker_id * length) / total_workers;
2335 size_t cur_pos = start_pos;
2336
2337 do {
2338 uint region_idx = regions[cur_pos];
2339 if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) {
2340 HeapRegion* r = region_at(region_idx);
2341 bool result = cl->do_heap_region(r);
2342 guarantee(!result, "Must not cancel iteration");
2343 }
2344
2345 cur_pos++;
2346 if (cur_pos == length) {
2347 cur_pos = 0;
2348 }
2349 } while (cur_pos != start_pos);
2350 }
2351
2352 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2353 HeapRegion* hr = heap_region_containing(addr);
2354 // The CollectedHeap API requires us to not fail for any given address within
2355 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2356 // outside of the allocated area.
2357 if (addr >= hr->top()) {
2358 return nullptr;
2359 }
2360 return hr->block_start(addr);
2361 }
2362
2363 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2364 HeapRegion* hr = heap_region_containing(addr);
2365 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2366 }
2367
2368 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2369 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2370 }
2371
2372 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2373 return _eden.length() * HeapRegion::GrainBytes;
2374 }
2375
2376 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2377 // must be equal to the humongous object limit.
2378 size_t G1CollectedHeap::max_tlab_size() const {
2379 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2380 }
2381
2382 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2383 return _allocator->unsafe_max_tlab_alloc();
2384 }
2385
2386 size_t G1CollectedHeap::max_capacity() const {
2387 return max_regions() * HeapRegion::GrainBytes;
2388 }
2389
2390 void G1CollectedHeap::prepare_for_verify() {
2391 _verifier->prepare_for_verify();
2392 }
2393
2394 void G1CollectedHeap::verify(VerifyOption vo) {
2395 _verifier->verify(vo);
2396 }
2397
2398 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2399 return true;
2400 }
2401
2402 bool G1CollectedHeap::is_archived_object(oop object) const {
2403 return object != NULL && heap_region_containing(object)->is_archive();
2404 }
2405
2406 class PrintRegionClosure: public HeapRegionClosure {
2407 outputStream* _st;
2408 public:
2409 PrintRegionClosure(outputStream* st) : _st(st) {}
2410 bool do_heap_region(HeapRegion* r) {
2411 r->print_on(_st);
2412 return false;
2413 }
2414 };
2415
2416 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2417 const HeapRegion* hr,
2418 const VerifyOption vo) const {
2419 switch (vo) {
2420 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2421 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2422 default: ShouldNotReachHere();
2423 }
2424 return false; // keep some compilers happy
2425 }
2426
2427 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2428 const VerifyOption vo) const {
2429 switch (vo) {
2430 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2431 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2432 default: ShouldNotReachHere();
2433 }
2434 return false; // keep some compilers happy
2435 }
2436
2437 void G1CollectedHeap::print_heap_regions() const {
2438 LogTarget(Trace, gc, heap, region) lt;
2439 if (lt.is_enabled()) {
2440 LogStream ls(lt);
2441 print_regions_on(&ls);
2442 }
2443 }
2444
2445 void G1CollectedHeap::print_on(outputStream* st) const {
2446 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2447 st->print(" %-20s", "garbage-first heap");
2448 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2449 capacity()/K, heap_used/K);
2450 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2451 p2i(_hrm.reserved().start()),
2452 p2i(_hrm.reserved().end()));
2453 st->cr();
2454 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2455 uint young_regions = young_regions_count();
2456 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2457 (size_t) young_regions * HeapRegion::GrainBytes / K);
2458 uint survivor_regions = survivor_regions_count();
2459 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2460 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2461 st->cr();
2462 if (_numa->is_enabled()) {
2463 uint num_nodes = _numa->num_active_nodes();
2464 st->print(" remaining free region(s) on each NUMA node: ");
2465 const int* node_ids = _numa->node_ids();
2466 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2467 uint num_free_regions = _hrm.num_free_regions(node_index);
2468 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2469 }
2470 st->cr();
2471 }
2472 MetaspaceUtils::print_on(st);
2473 }
2474
2475 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2476 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2477 "HS=humongous(starts), HC=humongous(continues), "
2478 "CS=collection set, F=free, "
2479 "OA=open archive, CA=closed archive, "
2480 "TAMS=top-at-mark-start, "
2481 "PB=parsable bottom");
2482 PrintRegionClosure blk(st);
2483 heap_region_iterate(&blk);
2484 }
2485
2486 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2487 print_on(st);
2488
2489 // Print the per-region information.
2490 st->cr();
2491 print_regions_on(st);
2492 }
2493
2494 void G1CollectedHeap::print_on_error(outputStream* st) const {
2495 this->CollectedHeap::print_on_error(st);
2496
2497 if (_cm != NULL) {
2498 st->cr();
2499 _cm->print_on_error(st);
2500 }
2501 }
2502
2503 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2504 workers()->threads_do(tc);
2505 tc->do_thread(_cm_thread);
2506 _cm->threads_do(tc);
2507 _cr->threads_do(tc);
2508 tc->do_thread(_service_thread);
2509 }
2510
2511 void G1CollectedHeap::print_tracing_info() const {
2512 rem_set()->print_summary_info();
2513 concurrent_mark()->print_summary_info();
2514 }
2515
2516 #ifndef PRODUCT
2517 // Helpful for debugging RSet issues.
2518
2519 class PrintRSetsClosure : public HeapRegionClosure {
2520 private:
2521 const char* _msg;
2522 size_t _occupied_sum;
2523
2524 public:
2525 bool do_heap_region(HeapRegion* r) {
2526 HeapRegionRemSet* hrrs = r->rem_set();
2527 size_t occupied = hrrs->occupied();
2528 _occupied_sum += occupied;
2529
2530 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2531 if (occupied == 0) {
2532 tty->print_cr(" RSet is empty");
2533 } else {
2534 tty->print_cr("hrrs " PTR_FORMAT, p2i(hrrs));
2535 }
2536 tty->print_cr("----------");
2537 return false;
2538 }
2539
2540 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2541 tty->cr();
2542 tty->print_cr("========================================");
2543 tty->print_cr("%s", msg);
2544 tty->cr();
2545 }
2546
2547 ~PrintRSetsClosure() {
2548 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2549 tty->print_cr("========================================");
2550 tty->cr();
2551 }
2552 };
2553
2554 void G1CollectedHeap::print_cset_rsets() {
2555 PrintRSetsClosure cl("Printing CSet RSets");
2556 collection_set_iterate_all(&cl);
2557 }
2558
2559 void G1CollectedHeap::print_all_rsets() {
2560 PrintRSetsClosure cl("Printing All RSets");;
2561 heap_region_iterate(&cl);
2562 }
2563 #endif // PRODUCT
2564
2565 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2566 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2567 }
2568
2569 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2570
2571 size_t eden_used_bytes = _eden.used_bytes();
2572 size_t survivor_used_bytes = _survivor.used_bytes();
2573 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2574
2575 size_t eden_capacity_bytes =
2576 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2577
2578 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2579 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2580 eden_capacity_bytes, survivor_used_bytes, num_regions());
2581 }
2582
2583 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2584 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2585 stats->unused(), stats->used(), stats->region_end_waste(),
2586 stats->regions_filled(), stats->num_plab_filled(),
2587 stats->direct_allocated(), stats->num_direct_allocated(),
2588 stats->failure_used(), stats->failure_waste());
2589 }
2590
2591 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2592 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2593 gc_tracer->report_gc_heap_summary(when, heap_summary);
2594
2595 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2596 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2597 }
2598
2599 void G1CollectedHeap::gc_prologue(bool full) {
2600 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2601
2602 // Update common counters.
2603 increment_total_collections(full /* full gc */);
2604 if (full || collector_state()->in_concurrent_start_gc()) {
2605 increment_old_marking_cycles_started();
2606 }
2607 }
2608
2609 void G1CollectedHeap::gc_epilogue(bool full) {
2610 // Update common counters.
2611 if (full) {
2612 // Update the number of full collections that have been completed.
2613 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2614 }
2615
2616 #if COMPILER2_OR_JVMCI
2617 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2618 #endif
2619
2620 // We have just completed a GC. Update the soft reference
2621 // policy with the new heap occupancy
2622 Universe::heap()->update_capacity_and_used_at_gc();
2623
2624 _collection_pause_end = Ticks::now();
2625
2626 _free_segmented_array_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2627 &_collection_set_candidates_card_set_stats);
2628 }
2629
2630 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2631 return _hrm.uncommit_inactive_regions(region_limit);
2632 }
2633
2634 bool G1CollectedHeap::has_uncommittable_regions() {
2635 return _hrm.has_inactive_regions();
2636 }
2637
2638 void G1CollectedHeap::uncommit_regions_if_necessary() {
2639 if (has_uncommittable_regions()) {
2640 G1UncommitRegionTask::enqueue();
2641 }
2642 }
2643
2644 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2645 LogTarget(Trace, gc, heap, verify) lt;
2646
2647 if (lt.is_enabled()) {
2648 LogStream ls(lt);
2649 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2650 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2651 heap_region_iterate(&cl);
2652 }
2653 }
2654
2655 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2656 uint gc_count_before,
2657 bool* succeeded,
2658 GCCause::Cause gc_cause) {
2659 assert_heap_not_locked_and_not_at_safepoint();
2660 VM_G1CollectForAllocation op(word_size,
2661 gc_count_before,
2662 gc_cause,
2663 policy()->max_pause_time_ms());
2664 VMThread::execute(&op);
2665
2666 HeapWord* result = op.result();
2667 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2668 assert(result == NULL || ret_succeeded,
2669 "the result should be NULL if the VM did not succeed");
2670 *succeeded = ret_succeeded;
2671
2672 assert_heap_not_locked();
2673 return result;
2674 }
2675
2676 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2677 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2678
2679 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2680 if (concurrent_operation_is_full_mark) {
2681 _cm->post_concurrent_mark_start();
2682 _cm_thread->start_full_mark();
2683 } else {
2684 _cm->post_concurrent_undo_start();
2685 _cm_thread->start_undo_mark();
2686 }
2687 CGC_lock->notify();
2688 }
2689
2690 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2691 // We don't nominate objects with many remembered set entries, on
2692 // the assumption that such objects are likely still live.
2693 HeapRegionRemSet* rem_set = r->rem_set();
2694
2695 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2696 }
2697
2698 #ifndef PRODUCT
2699 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2700 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2701 public:
2702 virtual bool do_heap_region(HeapRegion* r) {
2703 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2704 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2705 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2706 "Region %u remset tracking status (%s) different to region attribute (%s)",
2707 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2708 return false;
2709 }
2710 } cl;
2711 heap_region_iterate(&cl);
2712 }
2713 #endif
2714
2715 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2716 public:
2717 bool do_heap_region(HeapRegion* hr) {
2718 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2719 hr->verify_rem_set();
2720 }
2721 return false;
2722 }
2723 };
2724
2725 void G1CollectedHeap::start_new_collection_set() {
2726 double start = os::elapsedTime();
2727
2728 collection_set()->start_incremental_building();
2729
2730 clear_region_attr();
2731
2732 guarantee(_eden.length() == 0, "eden should have been cleared");
2733 policy()->transfer_survivors_to_cset(survivor());
2734
2735 // We redo the verification but now wrt to the new CSet which
2736 // has just got initialized after the previous CSet was freed.
2737 _cm->verify_no_collection_set_oops();
2738
2739 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2740 }
2741
2742 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2743 if (collector_state()->in_concurrent_start_gc()) {
2744 return G1HeapVerifier::G1VerifyConcurrentStart;
2745 } else if (collector_state()->in_young_only_phase()) {
2746 return G1HeapVerifier::G1VerifyYoungNormal;
2747 } else {
2748 return G1HeapVerifier::G1VerifyMixed;
2749 }
2750 }
2751
2752 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2753 if (!VerifyBeforeGC) {
2754 return;
2755 }
2756 Ticks start = Ticks::now();
2757 _verifier->prepare_for_verify();
2758 _verifier->verify_region_sets_optional();
2759 _verifier->verify_dirty_young_regions();
2760 if (VerifyRememberedSets) {
2761 log_info(gc, verify)("[Verifying RemSets before GC]");
2762 VerifyRegionRemSetClosure v_cl;
2763 heap_region_iterate(&v_cl);
2764 }
2765 _verifier->verify_before_gc(type);
2766 verify_numa_regions("GC Start");
2767 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2768 }
2769
2770 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2771 if (!VerifyAfterGC) {
2772 return;
2773 }
2774 Ticks start = Ticks::now();
2775 if (VerifyRememberedSets) {
2776 log_info(gc, verify)("[Verifying RemSets after GC]");
2777 VerifyRegionRemSetClosure v_cl;
2778 heap_region_iterate(&v_cl);
2779 }
2780 _verifier->verify_after_gc(type);
2781 verify_numa_regions("GC End");
2782 _verifier->verify_region_sets_optional();
2783 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2784 }
2785
2786 void G1CollectedHeap::expand_heap_after_young_collection(){
2787 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2788 if (expand_bytes > 0) {
2789 // No need for an ergo logging here,
2790 // expansion_amount() does this when it returns a value > 0.
2791 double expand_ms = 0.0;
2792 if (!expand(expand_bytes, _workers, &expand_ms)) {
2793 // We failed to expand the heap. Cannot do anything about it.
2794 }
2795 phase_times()->record_expand_heap_time(expand_ms);
2796 }
2797 }
2798
2799 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2800 assert_at_safepoint_on_vm_thread();
2801 guarantee(!is_gc_active(), "collection is not reentrant");
2802
2803 if (GCLocker::check_active_before_gc()) {
2804 return false;
2805 }
2806
2807 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2808 return true;
2809 }
2810
2811 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2812 // This summary needs to be printed before incrementing total collections.
2813 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2814 _g1h->total_collections(),
2815 true /* show_thread_times */);
2816 _g1h->print_heap_before_gc();
2817 _g1h->print_heap_regions();
2818 }
2819
2820 G1HeapPrinterMark::~G1HeapPrinterMark() {
2821 _g1h->policy()->print_age_table();
2822 _g1h->rem_set()->print_coarsen_stats();
2823 // We are at the end of the GC. Total collections has already been increased.
2824 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2825 _g1h->total_collections() - 1,
2826 false /* show_thread_times */);
2827
2828 _heap_transition.print();
2829 _g1h->print_heap_regions();
2830 _g1h->print_heap_after_gc();
2831 // Print NUMA statistics.
2832 _g1h->numa()->print_statistics();
2833 }
2834
2835 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2836 _timer(timer), _tracer(tracer) {
2837
2838 _timer->register_gc_start();
2839 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2840 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2841 }
2842
2843 G1JFRTracerMark::~G1JFRTracerMark() {
2844 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2845 _timer->register_gc_end();
2846 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2847 }
2848
2849 void G1CollectedHeap::prepare_tlabs_for_mutator() {
2850 Ticks start = Ticks::now();
2851
2852 _survivor_evac_stats.adjust_desired_plab_size();
2853 _old_evac_stats.adjust_desired_plab_size();
2854
2855 allocate_dummy_regions();
2856
2857 _allocator->init_mutator_alloc_regions();
2858
2859 resize_all_tlabs();
2860
2861 phase_times()->record_resize_tlab_time_ms((Ticks::now() - start).seconds() * 1000.0);
2862 }
2863
2864 void G1CollectedHeap::retire_tlabs() {
2865 ensure_parsability(true);
2866 }
2867
2868 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2869 ResourceMark rm;
2870
2871 IsGCActiveMark active_gc_mark;
2872 GCIdMark gc_id_mark;
2873 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2874
2875 GCTraceCPUTime tcpu(_gc_tracer_stw);
2876
2877 _bytes_used_during_gc = 0;
2878
2879 policy()->decide_on_concurrent_start_pause();
2880 // Record whether this pause may need to trigger a concurrent operation. Later,
2881 // when we signal the G1ConcurrentMarkThread, the collector state has already
2882 // been reset for the next pause.
2883 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2884
2885 // Perform the collection.
2886 G1YoungCollector collector(gc_cause(), target_pause_time_ms);
2887 collector.collect();
2888
2889 // It should now be safe to tell the concurrent mark thread to start
2890 // without its logging output interfering with the logging output
2891 // that came from the pause.
2892 if (should_start_concurrent_mark_operation) {
2893 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2894 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2895 // thread(s) could be running concurrently with us. Make sure that anything
2896 // after this point does not assume that we are the only GC thread running.
2897 // Note: of course, the actual marking work will not start until the safepoint
2898 // itself is released in SuspendibleThreadSet::desynchronize().
2899 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2900 ConcurrentGCBreakpoints::notify_idle_to_active();
2901 }
2902 }
2903
2904 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2905 uint num_workers = workers()->active_workers();
2906 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2907 workers()->run_task(&unlink_task);
2908 }
2909
2910 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2911 assert(obj != NULL, "must not be NULL");
2912 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2913 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2914 // may falsely indicate that this is not the case here: however the collection set only
2915 // contains old regions when concurrent mark is not running.
2916 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2917 }
2918
2919 void G1CollectedHeap::make_pending_list_reachable() {
2920 if (collector_state()->in_concurrent_start_gc()) {
2921 oop pll_head = Universe::reference_pending_list();
2922 if (pll_head != NULL) {
2923 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2924 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2925 }
2926 }
2927 }
2928
2929 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2930 _num_humongous_objects = num_humongous_total;
2931 _num_humongous_reclaim_candidates = num_humongous_candidates;
2932 }
2933
2934 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2935 G1CollectionSetCandidates* candidates = G1CollectedHeap::heap()->collection_set()->candidates();
2936 return candidates != NULL && candidates->num_remaining() > 0;
2937 }
2938
2939 void G1CollectedHeap::set_collection_set_candidates_stats(G1SegmentedArrayMemoryStats& stats) {
2940 _collection_set_candidates_card_set_stats = stats;
2941 }
2942
2943 void G1CollectedHeap::set_young_gen_card_set_stats(const G1SegmentedArrayMemoryStats& stats) {
2944 _young_gen_card_set_stats = stats;
2945 }
2946
2947 void G1CollectedHeap::record_obj_copy_mem_stats() {
2948 policy()->old_gen_alloc_tracker()->
2949 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2950
2951 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2952 create_g1_evac_summary(&_old_evac_stats));
2953 }
2954
2955 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2956 concurrent_mark()->clear_bitmap_for_region(hr);
2957 }
2958
2959 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2960 assert(!hr->is_free(), "the region should not be free");
2961 assert(!hr->is_empty(), "the region should not be empty");
2962 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2963
2964 // Clear the card counts for this region.
2965 // Note: we only need to do this if the region is not young
2966 // (since we don't refine cards in young regions).
2967 if (!hr->is_young()) {
2968 _hot_card_cache->reset_card_counts(hr);
2969 }
2970
2971 // Reset region metadata to allow reuse.
2972 hr->hr_clear(true /* clear_space */);
2973 _policy->remset_tracker()->update_at_free(hr);
2974
2975 if (free_list != NULL) {
2976 free_list->add_ordered(hr);
2977 }
2978 }
2979
2980 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2981 FreeRegionList* free_list) {
2982 assert(hr->is_humongous(), "this is only for humongous regions");
2983 hr->clear_humongous();
2984 free_region(hr, free_list);
2985 }
2986
2987 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2988 const uint archive_regions_removed,
2989 const uint humongous_regions_removed) {
2990 if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) {
2991 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2992 _old_set.bulk_remove(old_regions_removed);
2993 _archive_set.bulk_remove(archive_regions_removed);
2994 _humongous_set.bulk_remove(humongous_regions_removed);
2995 }
2996
2997 }
2998
2999 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3000 assert(list != NULL, "list can't be null");
3001 if (!list->is_empty()) {
3002 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3003 _hrm.insert_list_into_free_list(list);
3004 }
3005 }
3006
3007 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3008 decrease_used(bytes);
3009 }
3010
3011 void G1CollectedHeap::clear_eden() {
3012 _eden.clear();
3013 }
3014
3015 void G1CollectedHeap::clear_collection_set() {
3016 collection_set()->clear();
3017 }
3018
3019 void G1CollectedHeap::rebuild_free_region_list() {
3020 Ticks start = Ticks::now();
3021 _hrm.rebuild_free_list(workers());
3022 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
3023 }
3024
3025 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
3026 public:
3027 virtual bool do_heap_region(HeapRegion* r) {
3028 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
3029 G1CollectedHeap::heap()->clear_region_attr(r);
3030 r->clear_young_index_in_cset();
3031 return false;
3032 }
3033 };
3034
3035 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
3036 G1AbandonCollectionSetClosure cl;
3037 collection_set_iterate_all(&cl);
3038
3039 collection_set->clear();
3040 collection_set->stop_incremental_building();
3041 }
3042
3043 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
3044 return _allocator->is_retained_old_region(hr);
3045 }
3046
3047 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
3048 _eden.add(hr);
3049 _policy->set_region_eden(hr);
3050 }
3051
3052 #ifdef ASSERT
3053
3054 class NoYoungRegionsClosure: public HeapRegionClosure {
3055 private:
3056 bool _success;
3057 public:
3058 NoYoungRegionsClosure() : _success(true) { }
3059 bool do_heap_region(HeapRegion* r) {
3060 if (r->is_young()) {
3061 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
3062 p2i(r->bottom()), p2i(r->end()));
3063 _success = false;
3064 }
3065 return false;
3066 }
3067 bool success() { return _success; }
3068 };
3069
3070 bool G1CollectedHeap::check_young_list_empty() {
3071 bool ret = (young_regions_count() == 0);
3072
3073 NoYoungRegionsClosure closure;
3074 heap_region_iterate(&closure);
3075 ret = ret && closure.success();
3076
3077 return ret;
3078 }
3079
3080 #endif // ASSERT
3081
3082 // Remove the given HeapRegion from the appropriate region set.
3083 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
3084 if (hr->is_archive()) {
3085 _archive_set.remove(hr);
3086 } else if (hr->is_humongous()) {
3087 _humongous_set.remove(hr);
3088 } else if (hr->is_old()) {
3089 _old_set.remove(hr);
3090 } else if (hr->is_young()) {
3091 // Note that emptying the eden and survivor lists is postponed and instead
3092 // done as the first step when rebuilding the regions sets again. The reason
3093 // for this is that during a full GC string deduplication needs to know if
3094 // a collected region was young or old when the full GC was initiated.
3095 hr->uninstall_surv_rate_group();
3096 } else {
3097 // We ignore free regions, we'll empty the free list afterwards.
3098 assert(hr->is_free(), "it cannot be another type");
3099 }
3100 }
3101
3102 void G1CollectedHeap::increase_used(size_t bytes) {
3103 _summary_bytes_used += bytes;
3104 }
3105
3106 void G1CollectedHeap::decrease_used(size_t bytes) {
3107 assert(_summary_bytes_used >= bytes,
3108 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
3109 _summary_bytes_used, bytes);
3110 _summary_bytes_used -= bytes;
3111 }
3112
3113 void G1CollectedHeap::set_used(size_t bytes) {
3114 _summary_bytes_used = bytes;
3115 }
3116
3117 class RebuildRegionSetsClosure : public HeapRegionClosure {
3118 private:
3119 bool _free_list_only;
3120
3121 HeapRegionSet* _old_set;
3122 HeapRegionSet* _archive_set;
3123 HeapRegionSet* _humongous_set;
3124
3125 HeapRegionManager* _hrm;
3126
3127 size_t _total_used;
3128
3129 public:
3130 RebuildRegionSetsClosure(bool free_list_only,
3131 HeapRegionSet* old_set,
3132 HeapRegionSet* archive_set,
3133 HeapRegionSet* humongous_set,
3134 HeapRegionManager* hrm) :
3135 _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set),
3136 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
3137 assert(_hrm->num_free_regions() == 0, "pre-condition");
3138 if (!free_list_only) {
3139 assert(_old_set->is_empty(), "pre-condition");
3140 assert(_archive_set->is_empty(), "pre-condition");
3141 assert(_humongous_set->is_empty(), "pre-condition");
3142 }
3143 }
3144
3145 bool do_heap_region(HeapRegion* r) {
3146 if (r->is_empty()) {
3147 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
3148 // Add free regions to the free list
3149 r->set_free();
3150 _hrm->insert_into_free_list(r);
3151 } else if (!_free_list_only) {
3152 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
3153
3154 if (r->is_humongous()) {
3155 _humongous_set->add(r);
3156 } else if (r->is_archive()) {
3157 _archive_set->add(r);
3158 } else {
3159 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
3160 // We now move all (non-humongous, non-old, non-archive) regions to old gen,
3161 // and register them as such.
3162 r->move_to_old();
3163 _old_set->add(r);
3164 }
3165 _total_used += r->used();
3166 }
3167
3168 return false;
3169 }
3170
3171 size_t total_used() {
3172 return _total_used;
3173 }
3174 };
3175
3176 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
3177 assert_at_safepoint_on_vm_thread();
3178
3179 if (!free_list_only) {
3180 _eden.clear();
3181 _survivor.clear();
3182 }
3183
3184 RebuildRegionSetsClosure cl(free_list_only,
3185 &_old_set, &_archive_set, &_humongous_set,
3186 &_hrm);
3187 heap_region_iterate(&cl);
3188
3189 if (!free_list_only) {
3190 set_used(cl.total_used());
3191 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
3192 }
3193 assert_used_and_recalculate_used_equal(this);
3194 }
3195
3196 // Methods for the mutator alloc region
3197
3198 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
3199 bool force,
3200 uint node_index) {
3201 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3202 bool should_allocate = policy()->should_allocate_mutator_region();
3203 if (force || should_allocate) {
3204 HeapRegion* new_alloc_region = new_region(word_size,
3205 HeapRegionType::Eden,
3206 false /* do_expand */,
3207 node_index);
3208 if (new_alloc_region != NULL) {
3209 set_region_short_lived_locked(new_alloc_region);
3210 _hr_printer.alloc(new_alloc_region, !should_allocate);
3211 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3212 return new_alloc_region;
3213 }
3214 }
3215 return NULL;
3216 }
3217
3218 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
3219 size_t allocated_bytes) {
3220 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3221 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
3222
3223 collection_set()->add_eden_region(alloc_region);
3224 increase_used(allocated_bytes);
3225 _eden.add_used_bytes(allocated_bytes);
3226 _hr_printer.retire(alloc_region);
3227
3228 // We update the eden sizes here, when the region is retired,
3229 // instead of when it's allocated, since this is the point that its
3230 // used space has been recorded in _summary_bytes_used.
3231 monitoring_support()->update_eden_size();
3232 }
3233
3234 // Methods for the GC alloc regions
3235
3236 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
3237 if (dest.is_old()) {
3238 return true;
3239 } else {
3240 return survivor_regions_count() < policy()->max_survivor_regions();
3241 }
3242 }
3243
3244 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
3245 assert(FreeList_lock->owned_by_self(), "pre-condition");
3246
3247 if (!has_more_regions(dest)) {
3248 return NULL;
3249 }
3250
3251 HeapRegionType type;
3252 if (dest.is_young()) {
3253 type = HeapRegionType::Survivor;
3254 } else {
3255 type = HeapRegionType::Old;
3256 }
3257
3258 HeapRegion* new_alloc_region = new_region(word_size,
3259 type,
3260 true /* do_expand */,
3261 node_index);
3262
3263 if (new_alloc_region != NULL) {
3264 if (type.is_survivor()) {
3265 new_alloc_region->set_survivor();
3266 _survivor.add(new_alloc_region);
3267 register_new_survivor_region_with_region_attr(new_alloc_region);
3268 } else {
3269 new_alloc_region->set_old();
3270 }
3271 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3272 register_region_with_region_attr(new_alloc_region);
3273 _hr_printer.alloc(new_alloc_region);
3274 return new_alloc_region;
3275 }
3276 return NULL;
3277 }
3278
3279 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
3280 size_t allocated_bytes,
3281 G1HeapRegionAttr dest) {
3282 _bytes_used_during_gc += allocated_bytes;
3283 if (dest.is_old()) {
3284 old_set_add(alloc_region);
3285 } else {
3286 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
3287 _survivor.add_used_bytes(allocated_bytes);
3288 }
3289
3290 bool const during_im = collector_state()->in_concurrent_start_gc();
3291 if (during_im && allocated_bytes > 0) {
3292 _cm->add_root_region(alloc_region);
3293 }
3294 _hr_printer.retire(alloc_region);
3295 }
3296
3297 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
3298 bool expanded = false;
3299 uint index = _hrm.find_highest_free(&expanded);
3300
3301 if (index != G1_NO_HRM_INDEX) {
3302 if (expanded) {
3303 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
3304 HeapRegion::GrainWords * HeapWordSize);
3305 }
3306 return _hrm.allocate_free_regions_starting_at(index, 1);
3307 }
3308 return NULL;
3309 }
3310
3311 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
3312 assert(!_cm->is_marked_in_bitmap(obj), "must be");
3313
3314 _cm->raw_mark_in_bitmap(obj);
3315 if (collector_state()->in_concurrent_start_gc()) {
3316 _cm->add_to_liveness(worker_id, obj, obj_size);
3317 }
3318 }
3319
3320 // Optimized nmethod scanning
3321 class RegisterNMethodOopClosure: public OopClosure {
3322 G1CollectedHeap* _g1h;
3323 nmethod* _nm;
3324
3325 public:
3326 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3327 _g1h(g1h), _nm(nm) {}
3328
3329 void do_oop(oop* p) {
3330 oop heap_oop = RawAccess<>::oop_load(p);
3331 if (!CompressedOops::is_null(heap_oop)) {
3332 oop obj = CompressedOops::decode_not_null(heap_oop);
3333 HeapRegion* hr = _g1h->heap_region_containing(obj);
3334 assert(!hr->is_continues_humongous(),
3335 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3336 " starting at " HR_FORMAT,
3337 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3338
3339 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3340 hr->add_code_root_locked(_nm);
3341 }
3342 }
3343
3344 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3345 };
3346
3347 class UnregisterNMethodOopClosure: public OopClosure {
3348 G1CollectedHeap* _g1h;
3349 nmethod* _nm;
3350
3351 public:
3352 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3353 _g1h(g1h), _nm(nm) {}
3354
3355 void do_oop(oop* p) {
3356 oop heap_oop = RawAccess<>::oop_load(p);
3357 if (!CompressedOops::is_null(heap_oop)) {
3358 oop obj = CompressedOops::decode_not_null(heap_oop);
3359 HeapRegion* hr = _g1h->heap_region_containing(obj);
3360 assert(!hr->is_continues_humongous(),
3361 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3362 " starting at " HR_FORMAT,
3363 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3364
3365 hr->remove_code_root(_nm);
3366 }
3367 }
3368
3369 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3370 };
3371
3372 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3373 guarantee(nm != NULL, "sanity");
3374 RegisterNMethodOopClosure reg_cl(this, nm);
3375 nm->oops_do(®_cl);
3376 }
3377
3378 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3379 guarantee(nm != NULL, "sanity");
3380 UnregisterNMethodOopClosure reg_cl(this, nm);
3381 nm->oops_do(®_cl, true);
3382 }
3383
3384 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3385 if (evacuation_failed) {
3386 // Reset the G1EvacuationFailureALot counters and flags
3387 evac_failure_injector()->reset();
3388
3389 set_used(recalculate_used());
3390
3391 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
3392 } else {
3393 // The "used" of the collection set have already been subtracted
3394 // when they were freed. Add in the bytes used.
3395 increase_used(_bytes_used_during_gc);
3396 }
3397 }
3398
3399 void G1CollectedHeap::reset_hot_card_cache() {
3400 _hot_card_cache->reset_hot_cache();
3401 }
3402
3403 void G1CollectedHeap::purge_code_root_memory() {
3404 G1CodeRootSet::purge();
3405 }
3406
3407 class RebuildCodeRootClosure: public CodeBlobClosure {
3408 G1CollectedHeap* _g1h;
3409
3410 public:
3411 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3412 _g1h(g1h) {}
3413
3414 void do_code_blob(CodeBlob* cb) {
3415 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
3416 if (nm == NULL) {
3417 return;
3418 }
3419
3420 _g1h->register_nmethod(nm);
3421 }
3422 };
3423
3424 void G1CollectedHeap::rebuild_code_roots() {
3425 RebuildCodeRootClosure blob_cl(this);
3426 CodeCache::blobs_do(&blob_cl);
3427 }
3428
3429 void G1CollectedHeap::initialize_serviceability() {
3430 _monitoring_support->initialize_serviceability();
3431 }
3432
3433 MemoryUsage G1CollectedHeap::memory_usage() {
3434 return _monitoring_support->memory_usage();
3435 }
3436
3437 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3438 return _monitoring_support->memory_managers();
3439 }
3440
3441 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3442 return _monitoring_support->memory_pools();
3443 }
3444
3445 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3446 HeapRegion* region = heap_region_containing(start);
3447 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3448 }
3449
3450 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive() {
3451 if (!CodeCache::is_gc_marking_cycle_active()) {
3452 // This is the normal case when we do not call collect when a
3453 // concurrent mark is ongoing. We then start a new code marking
3454 // cycle. If, on the other hand, a concurrent mark is ongoing, we
3455 // will be conservative and use the last code marking cycle. Code
3456 // caches marked between the two concurrent marks will live a bit
3457 // longer than needed.
3458 CodeCache::on_gc_marking_cycle_start();
3459 CodeCache::arm_all_nmethods();
3460 }
3461 }