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.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "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/referenceProcessor.inline.hpp"
91 #include "gc/shared/suspendibleThreadSet.hpp"
92 #include "gc/shared/taskqueue.inline.hpp"
93 #include "gc/shared/taskTerminator.hpp"
94 #include "gc/shared/tlab_globals.hpp"
95 #include "gc/shared/workerPolicy.hpp"
96 #include "gc/shared/weakProcessor.inline.hpp"
97 #include "logging/log.hpp"
98 #include "memory/allocation.hpp"
99 #include "memory/heapInspection.hpp"
100 #include "memory/iterator.hpp"
101 #include "memory/metaspaceUtils.hpp"
102 #include "memory/resourceArea.hpp"
103 #include "memory/universe.hpp"
104 #include "oops/access.inline.hpp"
105 #include "oops/compressedOops.inline.hpp"
106 #include "oops/oop.inline.hpp"
107 #include "runtime/atomic.hpp"
108 #include "runtime/handles.inline.hpp"
109 #include "runtime/init.hpp"
110 #include "runtime/java.hpp"
111 #include "runtime/orderAccess.hpp"
112 #include "runtime/threadSMR.hpp"
113 #include "runtime/vmThread.hpp"
114 #include "utilities/align.hpp"
115 #include "utilities/autoRestore.hpp"
116 #include "utilities/bitMap.inline.hpp"
117 #include "utilities/globalDefinitions.hpp"
118 #include "utilities/stack.inline.hpp"
119
120 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
121
122 // INVARIANTS/NOTES
123 //
124 // All allocation activity covered by the G1CollectedHeap interface is
125 // serialized by acquiring the HeapLock. This happens in mem_allocate
126 // and allocate_new_tlab, which are the "entry" points to the
127 // allocation code from the rest of the JVM. (Note that this does not
128 // apply to TLAB allocation, which is not part of this interface: it
129 // is done by clients of this interface.)
130
131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
132 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
133 }
134
135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
136 // The from card cache is not the memory that is actually committed. So we cannot
137 // take advantage of the zero_filled parameter.
138 reset_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
142 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
143 cl->set_max_workers(num_workers);
144 workers()->run_task(cl, num_workers);
145 }
146
147 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
148 MemRegion mr) {
149 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
150 }
151
152 // Private methods.
153
154 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
155 HeapRegionType type,
156 bool do_expand,
157 uint node_index) {
158 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
159 "the only time we use this to allocate a humongous region is "
160 "when we are allocating a single humongous region");
161
162 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
163
164 if (res == NULL && do_expand) {
165 // Currently, only attempts to allocate GC alloc regions set
166 // do_expand to true. So, we should only reach here during a
167 // safepoint.
168 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
169
170 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
171 word_size * HeapWordSize);
172
173 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
174 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
175 word_size * HeapWordSize);
176 if (expand_single_region(node_index)) {
177 // Given that expand_single_region() succeeded in expanding the heap, and we
178 // always expand the heap by an amount aligned to the heap
179 // region size, the free list should in theory not be empty.
180 // In either case allocate_free_region() will check for NULL.
181 res = _hrm.allocate_free_region(type, node_index);
182 }
183 }
184 return res;
185 }
186
187 HeapWord*
188 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
189 uint num_regions,
190 size_t word_size) {
191 assert(first_hr != NULL, "pre-condition");
192 assert(is_humongous(word_size), "word_size should be humongous");
193 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
194
195 // Index of last region in the series.
196 uint first = first_hr->hrm_index();
197 uint last = first + num_regions - 1;
198
199 // We need to initialize the region(s) we just discovered. This is
200 // a bit tricky given that it can happen concurrently with
201 // refinement threads refining cards on these regions and
202 // potentially wanting to refine the BOT as they are scanning
203 // those cards (this can happen shortly after a cleanup; see CR
204 // 6991377). So we have to set up the region(s) carefully and in
205 // a specific order.
206
207 // The word size sum of all the regions we will allocate.
208 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
209 assert(word_size <= word_size_sum, "sanity");
210
211 // The passed in hr will be the "starts humongous" region. The header
212 // of the new object will be placed at the bottom of this region.
213 HeapWord* new_obj = first_hr->bottom();
214 // This will be the new top of the new object.
215 HeapWord* obj_top = new_obj + word_size;
216
217 // First, we need to zero the header of the space that we will be
218 // allocating. When we update top further down, some refinement
219 // threads might try to scan the region. By zeroing the header we
220 // ensure that any thread that will try to scan the region will
221 // come across the zero klass word and bail out.
222 //
223 // NOTE: It would not have been correct to have used
224 // CollectedHeap::fill_with_object() and make the space look like
225 // an int array. The thread that is doing the allocation will
226 // later update the object header to a potentially different array
227 // type and, for a very short period of time, the klass and length
228 // fields will be inconsistent. This could cause a refinement
229 // thread to calculate the object size incorrectly.
230 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
231
232 // Next, pad out the unused tail of the last region with filler
233 // objects, for improved usage accounting.
234 // How many words we use for filler objects.
235 size_t word_fill_size = word_size_sum - word_size;
236
237 // How many words memory we "waste" which cannot hold a filler object.
238 size_t words_not_fillable = 0;
239
240 if (word_fill_size >= min_fill_size()) {
241 fill_with_objects(obj_top, word_fill_size);
242 } else if (word_fill_size > 0) {
243 // We have space to fill, but we cannot fit an object there.
244 words_not_fillable = word_fill_size;
245 word_fill_size = 0;
246 }
247
248 // We will set up the first region as "starts humongous". This
249 // will also update the BOT covering all the regions to reflect
250 // that there is a single object that starts at the bottom of the
251 // first region.
252 first_hr->set_starts_humongous(obj_top, word_fill_size);
253 _policy->remset_tracker()->update_at_allocate(first_hr);
254 // Then, if there are any, we will set up the "continues
255 // humongous" regions.
256 HeapRegion* hr = NULL;
257 for (uint i = first + 1; i <= last; ++i) {
258 hr = region_at(i);
259 hr->set_continues_humongous(first_hr);
260 _policy->remset_tracker()->update_at_allocate(hr);
261 }
262
263 // Up to this point no concurrent thread would have been able to
264 // do any scanning on any region in this series. All the top
265 // fields still point to bottom, so the intersection between
266 // [bottom,top] and [card_start,card_end] will be empty. Before we
267 // update the top fields, we'll do a storestore to make sure that
268 // no thread sees the update to top before the zeroing of the
269 // object header and the BOT initialization.
270 OrderAccess::storestore();
271
272 // Now, we will update the top fields of the "continues humongous"
273 // regions except the last one.
274 for (uint i = first; i < last; ++i) {
275 hr = region_at(i);
276 hr->set_top(hr->end());
277 }
278
279 hr = region_at(last);
280 // If we cannot fit a filler object, we must set top to the end
281 // of the humongous object, otherwise we cannot iterate the heap
282 // and the BOT will not be complete.
283 hr->set_top(hr->end() - words_not_fillable);
284
285 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
286 "obj_top should be in last region");
287
288 assert(words_not_fillable == 0 ||
289 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
290 "Miscalculation in humongous allocation");
291
292 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
293
294 for (uint i = first; i <= last; ++i) {
295 hr = region_at(i);
296 _humongous_set.add(hr);
297 _hr_printer.alloc(hr);
298 }
299
300 return new_obj;
301 }
302
303 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
304 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
305 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
306 }
307
308 // If could fit into free regions w/o expansion, try.
309 // Otherwise, if can expand, do so.
310 // Otherwise, if using ex regions might help, try with ex given back.
311 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
312 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
313
314 _verifier->verify_region_sets_optional();
315
316 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
317
318 // Policy: First try to allocate a humongous object in the free list.
319 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
320 if (humongous_start == NULL) {
321 // Policy: We could not find enough regions for the humongous object in the
322 // free list. Look through the heap to find a mix of free and uncommitted regions.
323 // If so, expand the heap and allocate the humongous object.
324 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
325 if (humongous_start != NULL) {
326 // We managed to find a region by expanding the heap.
327 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
328 word_size * HeapWordSize);
329 policy()->record_new_heap_size(num_regions());
330 } else {
331 // Policy: Potentially trigger a defragmentation GC.
332 }
333 }
334
335 HeapWord* result = NULL;
336 if (humongous_start != NULL) {
337 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
338 assert(result != NULL, "it should always return a valid result");
339
340 // A successful humongous object allocation changes the used space
341 // information of the old generation so we need to recalculate the
342 // sizes and update the jstat counters here.
343 monitoring_support()->update_sizes();
344 }
345
346 _verifier->verify_region_sets_optional();
347
348 return result;
349 }
350
351 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
352 size_t requested_size,
353 size_t* actual_size) {
354 assert_heap_not_locked_and_not_at_safepoint();
355 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
356
357 return attempt_allocation(min_size, requested_size, actual_size);
358 }
359
360 HeapWord*
361 G1CollectedHeap::mem_allocate(size_t word_size,
362 bool* gc_overhead_limit_was_exceeded) {
363 assert_heap_not_locked_and_not_at_safepoint();
364
365 if (is_humongous(word_size)) {
366 return attempt_allocation_humongous(word_size);
367 }
368 size_t dummy = 0;
369 return attempt_allocation(word_size, word_size, &dummy);
370 }
371
372 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
373 ResourceMark rm; // For retrieving the thread names in log messages.
374
375 // Make sure you read the note in attempt_allocation_humongous().
376
377 assert_heap_not_locked_and_not_at_safepoint();
378 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
379 "be called for humongous allocation requests");
380
381 // We should only get here after the first-level allocation attempt
382 // (attempt_allocation()) failed to allocate.
383
384 // We will loop until a) we manage to successfully perform the
385 // allocation or b) we successfully schedule a collection which
386 // fails to perform the allocation. b) is the only case when we'll
387 // return NULL.
388 HeapWord* result = NULL;
389 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
390 bool should_try_gc;
391 bool preventive_collection_required = false;
392 uint gc_count_before;
393
394 {
395 MutexLocker x(Heap_lock);
396
397 // Now that we have the lock, we first retry the allocation in case another
398 // thread changed the region while we were waiting to acquire the lock.
399 size_t actual_size;
400 result = _allocator->attempt_allocation(word_size, word_size, &actual_size);
401 if (result != NULL) {
402 return result;
403 }
404
405 preventive_collection_required = policy()->preventive_collection_required(1);
406 if (!preventive_collection_required) {
407 // We've already attempted a lock-free allocation above, so we don't want to
408 // do it again. Let's jump straight to replacing the active region.
409 result = _allocator->attempt_allocation_using_new_region(word_size);
410 if (result != NULL) {
411 return result;
412 }
413
414 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
415 // This is different to when only GCLocker::needs_gc() is set: try to avoid
416 // waiting because the GCLocker is active to not wait too long.
417 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
418 // No need for an ergo message here, can_expand_young_list() does this when
419 // it returns true.
420 result = _allocator->attempt_allocation_force(word_size);
421 if (result != NULL) {
422 return result;
423 }
424 }
425 }
426
427 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
428 // the GCLocker initiated GC has been performed and then retry. This includes
429 // the case when the GC Locker is not active but has not been performed.
430 should_try_gc = !GCLocker::needs_gc();
431 // Read the GC count while still holding the Heap_lock.
432 gc_count_before = total_collections();
433 }
434
435 if (should_try_gc) {
436 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
437 : GCCause::_g1_inc_collection_pause;
438 bool succeeded;
439 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
440 if (result != NULL) {
441 assert(succeeded, "only way to get back a non-NULL result");
442 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
443 Thread::current()->name(), p2i(result));
444 return result;
445 }
446
447 if (succeeded) {
448 // We successfully scheduled a collection which failed to allocate. No
449 // point in trying to allocate further. We'll just return NULL.
450 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
451 SIZE_FORMAT " words", Thread::current()->name(), word_size);
452 return NULL;
453 }
454 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
455 Thread::current()->name(), word_size);
456 } else {
457 // Failed to schedule a collection.
458 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
459 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
460 SIZE_FORMAT " words", Thread::current()->name(), word_size);
461 return NULL;
462 }
463 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
464 // The GCLocker is either active or the GCLocker initiated
465 // GC has not yet been performed. Stall until it is and
466 // then retry the allocation.
467 GCLocker::stall_until_clear();
468 gclocker_retry_count += 1;
469 }
470
471 // We can reach here if we were unsuccessful in scheduling a
472 // collection (because another thread beat us to it) or if we were
473 // stalled due to the GC locker. In either can we should retry the
474 // allocation attempt in case another thread successfully
475 // performed a collection and reclaimed enough space. We do the
476 // first attempt (without holding the Heap_lock) here and the
477 // follow-on attempt will be at the start of the next loop
478 // iteration (after taking the Heap_lock).
479 size_t dummy = 0;
480 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
481 if (result != NULL) {
482 return result;
483 }
484
485 // Give a warning if we seem to be looping forever.
486 if ((QueuedAllocationWarningCount > 0) &&
487 (try_count % QueuedAllocationWarningCount == 0)) {
488 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
489 Thread::current()->name(), try_count, word_size);
490 }
491 }
492
493 ShouldNotReachHere();
494 return NULL;
495 }
496
497 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
498 assert_at_safepoint_on_vm_thread();
499 assert(_archive_allocator == nullptr, "should not be initialized");
500 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
501 }
502
503 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
504 // Allocations in archive regions cannot be of a size that would be considered
505 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
506 // may be different at archive-restore time.
507 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
508 }
509
510 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
511 assert_at_safepoint_on_vm_thread();
512 assert(_archive_allocator != nullptr, "_archive_allocator not initialized");
513 if (is_archive_alloc_too_large(word_size)) {
514 return nullptr;
515 }
516 return _archive_allocator->archive_mem_allocate(word_size);
517 }
518
519 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
520 size_t end_alignment_in_bytes) {
521 assert_at_safepoint_on_vm_thread();
522 assert(_archive_allocator != nullptr, "_archive_allocator not initialized");
523
524 // Call complete_archive to do the real work, filling in the MemRegion
525 // array with the archive regions.
526 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
527 delete _archive_allocator;
528 _archive_allocator = nullptr;
529 }
530
531 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
532 assert(ranges != NULL, "MemRegion array NULL");
533 assert(count != 0, "No MemRegions provided");
534 MemRegion reserved = _hrm.reserved();
535 for (size_t i = 0; i < count; i++) {
536 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
537 return false;
538 }
539 }
540 return true;
541 }
542
543 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
544 size_t count,
545 bool open) {
546 assert(!is_init_completed(), "Expect to be called at JVM init time");
547 assert(ranges != NULL, "MemRegion array NULL");
548 assert(count != 0, "No MemRegions provided");
549 MutexLocker x(Heap_lock);
550
551 MemRegion reserved = _hrm.reserved();
552 HeapWord* prev_last_addr = NULL;
553 HeapRegion* prev_last_region = NULL;
554
555 // Temporarily disable pretouching of heap pages. This interface is used
556 // when mmap'ing archived heap data in, so pre-touching is wasted.
557 FlagSetting fs(AlwaysPreTouch, false);
558
559 // For each specified MemRegion range, allocate the corresponding G1
560 // regions and mark them as archive regions. We expect the ranges
561 // in ascending starting address order, without overlap.
562 for (size_t i = 0; i < count; i++) {
563 MemRegion curr_range = ranges[i];
564 HeapWord* start_address = curr_range.start();
565 size_t word_size = curr_range.word_size();
566 HeapWord* last_address = curr_range.last();
567 size_t commits = 0;
568
569 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
570 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
571 p2i(start_address), p2i(last_address));
572 guarantee(start_address > prev_last_addr,
573 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
574 p2i(start_address), p2i(prev_last_addr));
575 prev_last_addr = last_address;
576
577 // Check for ranges that start in the same G1 region in which the previous
578 // range ended, and adjust the start address so we don't try to allocate
579 // the same region again. If the current range is entirely within that
580 // region, skip it, just adjusting the recorded top.
581 HeapRegion* start_region = _hrm.addr_to_region(start_address);
582 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
583 start_address = start_region->end();
584 if (start_address > last_address) {
585 increase_used(word_size * HeapWordSize);
586 start_region->set_top(last_address + 1);
587 continue;
588 }
589 start_region->set_top(start_address);
590 curr_range = MemRegion(start_address, last_address + 1);
591 start_region = _hrm.addr_to_region(start_address);
592 }
593
594 // Perform the actual region allocation, exiting if it fails.
595 // Then note how much new space we have allocated.
596 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
597 return false;
598 }
599 increase_used(word_size * HeapWordSize);
600 if (commits != 0) {
601 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
602 HeapRegion::GrainWords * HeapWordSize * commits);
603
604 }
605
606 // Mark each G1 region touched by the range as archive, add it to
607 // the old set, and set top.
608 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
609 HeapRegion* last_region = _hrm.addr_to_region(last_address);
610 prev_last_region = last_region;
611
612 while (curr_region != NULL) {
613 assert(curr_region->is_empty() && !curr_region->is_pinned(),
614 "Region already in use (index %u)", curr_region->hrm_index());
615 if (open) {
616 curr_region->set_open_archive();
617 } else {
618 curr_region->set_closed_archive();
619 }
620 _hr_printer.alloc(curr_region);
621 _archive_set.add(curr_region);
622 HeapWord* top;
623 HeapRegion* next_region;
624 if (curr_region != last_region) {
625 top = curr_region->end();
626 next_region = _hrm.next_region_in_heap(curr_region);
627 } else {
628 top = last_address + 1;
629 next_region = NULL;
630 }
631 curr_region->set_top(top);
632 curr_region = next_region;
633 }
634 }
635 return true;
636 }
637
638 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
639 assert(!is_init_completed(), "Expect to be called at JVM init time");
640 assert(ranges != NULL, "MemRegion array NULL");
641 assert(count != 0, "No MemRegions provided");
642 MemRegion reserved = _hrm.reserved();
643 HeapWord *prev_last_addr = NULL;
644 HeapRegion* prev_last_region = NULL;
645
646 // For each MemRegion, create filler objects, if needed, in the G1 regions
647 // that contain the address range. The address range actually within the
648 // MemRegion will not be modified. That is assumed to have been initialized
649 // elsewhere, probably via an mmap of archived heap data.
650 MutexLocker x(Heap_lock);
651 for (size_t i = 0; i < count; i++) {
652 HeapWord* start_address = ranges[i].start();
653 HeapWord* last_address = ranges[i].last();
654
655 assert(reserved.contains(start_address) && reserved.contains(last_address),
656 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
657 p2i(start_address), p2i(last_address));
658 assert(start_address > prev_last_addr,
659 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
660 p2i(start_address), p2i(prev_last_addr));
661
662 HeapRegion* start_region = _hrm.addr_to_region(start_address);
663 HeapRegion* last_region = _hrm.addr_to_region(last_address);
664 HeapWord* bottom_address = start_region->bottom();
665
666 // Check for a range beginning in the same region in which the
667 // previous one ended.
668 if (start_region == prev_last_region) {
669 bottom_address = prev_last_addr + 1;
670 }
671
672 // Verify that the regions were all marked as archive regions by
673 // alloc_archive_regions.
674 HeapRegion* curr_region = start_region;
675 while (curr_region != NULL) {
676 guarantee(curr_region->is_archive(),
677 "Expected archive region at index %u", curr_region->hrm_index());
678 if (curr_region != last_region) {
679 curr_region = _hrm.next_region_in_heap(curr_region);
680 } else {
681 curr_region = NULL;
682 }
683 }
684
685 prev_last_addr = last_address;
686 prev_last_region = last_region;
687
688 // Fill the memory below the allocated range with dummy object(s),
689 // if the region bottom does not match the range start, or if the previous
690 // range ended within the same G1 region, and there is a gap.
691 assert(start_address >= bottom_address, "bottom address should not be greater than start address");
692 if (start_address > bottom_address) {
693 size_t fill_size = pointer_delta(start_address, bottom_address);
694 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
695 increase_used(fill_size * HeapWordSize);
696 }
697 }
698 }
699
700 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
701 size_t desired_word_size,
702 size_t* actual_word_size) {
703 assert_heap_not_locked_and_not_at_safepoint();
704 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
705 "be called for humongous allocation requests");
706
707 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
708
709 if (result == NULL) {
710 *actual_word_size = desired_word_size;
711 result = attempt_allocation_slow(desired_word_size);
712 }
713
714 assert_heap_not_locked();
715 if (result != NULL) {
716 assert(*actual_word_size != 0, "Actual size must have been set here");
717 dirty_young_block(result, *actual_word_size);
718 } else {
719 *actual_word_size = 0;
720 }
721
722 return result;
723 }
724
725 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) {
726 assert(!is_init_completed(), "Expect to be called at JVM init time");
727 assert(ranges != NULL, "MemRegion array NULL");
728 assert(count != 0, "No MemRegions provided");
729
730 HeapWord* st = ranges[0].start();
731 HeapWord* last = ranges[count-1].last();
732 HeapRegion* hr_st = _hrm.addr_to_region(st);
733 HeapRegion* hr_last = _hrm.addr_to_region(last);
734
735 HeapRegion* hr_curr = hr_st;
736 while (hr_curr != NULL) {
737 hr_curr->update_bot();
738 if (hr_curr != hr_last) {
739 hr_curr = _hrm.next_region_in_heap(hr_curr);
740 } else {
741 hr_curr = NULL;
742 }
743 }
744 }
745
746 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
747 assert(!is_init_completed(), "Expect to be called at JVM init time");
748 assert(ranges != NULL, "MemRegion array NULL");
749 assert(count != 0, "No MemRegions provided");
750 MemRegion reserved = _hrm.reserved();
751 HeapWord* prev_last_addr = NULL;
752 HeapRegion* prev_last_region = NULL;
753 size_t size_used = 0;
754 uint shrink_count = 0;
755
756 // For each Memregion, free the G1 regions that constitute it, and
757 // notify mark-sweep that the range is no longer to be considered 'archive.'
758 MutexLocker x(Heap_lock);
759 for (size_t i = 0; i < count; i++) {
760 HeapWord* start_address = ranges[i].start();
761 HeapWord* last_address = ranges[i].last();
762
763 assert(reserved.contains(start_address) && reserved.contains(last_address),
764 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
765 p2i(start_address), p2i(last_address));
766 assert(start_address > prev_last_addr,
767 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
768 p2i(start_address), p2i(prev_last_addr));
769 size_used += ranges[i].byte_size();
770 prev_last_addr = last_address;
771
772 HeapRegion* start_region = _hrm.addr_to_region(start_address);
773 HeapRegion* last_region = _hrm.addr_to_region(last_address);
774
775 // Check for ranges that start in the same G1 region in which the previous
776 // range ended, and adjust the start address so we don't try to free
777 // the same region again. If the current range is entirely within that
778 // region, skip it.
779 if (start_region == prev_last_region) {
780 start_address = start_region->end();
781 if (start_address > last_address) {
782 continue;
783 }
784 start_region = _hrm.addr_to_region(start_address);
785 }
786 prev_last_region = last_region;
787
788 // After verifying that each region was marked as an archive region by
789 // alloc_archive_regions, set it free and empty and uncommit it.
790 HeapRegion* curr_region = start_region;
791 while (curr_region != NULL) {
792 guarantee(curr_region->is_archive(),
793 "Expected archive region at index %u", curr_region->hrm_index());
794 uint curr_index = curr_region->hrm_index();
795 _archive_set.remove(curr_region);
796 curr_region->set_free();
797 curr_region->set_top(curr_region->bottom());
798 if (curr_region != last_region) {
799 curr_region = _hrm.next_region_in_heap(curr_region);
800 } else {
801 curr_region = NULL;
802 }
803
804 _hrm.shrink_at(curr_index, 1);
805 shrink_count++;
806 }
807 }
808
809 if (shrink_count != 0) {
810 log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B",
811 HeapRegion::GrainWords * HeapWordSize * shrink_count);
812 // Explicit uncommit.
813 uncommit_regions(shrink_count);
814 }
815 decrease_used(size_used);
816 }
817
818 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
819 ResourceMark rm; // For retrieving the thread names in log messages.
820
821 // The structure of this method has a lot of similarities to
822 // attempt_allocation_slow(). The reason these two were not merged
823 // into a single one is that such a method would require several "if
824 // allocation is not humongous do this, otherwise do that"
825 // conditional paths which would obscure its flow. In fact, an early
826 // version of this code did use a unified method which was harder to
827 // follow and, as a result, it had subtle bugs that were hard to
828 // track down. So keeping these two methods separate allows each to
829 // be more readable. It will be good to keep these two in sync as
830 // much as possible.
831
832 assert_heap_not_locked_and_not_at_safepoint();
833 assert(is_humongous(word_size), "attempt_allocation_humongous() "
834 "should only be called for humongous allocations");
835
836 // Humongous objects can exhaust the heap quickly, so we should check if we
837 // need to start a marking cycle at each humongous object allocation. We do
838 // the check before we do the actual allocation. The reason for doing it
839 // before the allocation is that we avoid having to keep track of the newly
840 // allocated memory while we do a GC.
841 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
842 word_size)) {
843 collect(GCCause::_g1_humongous_allocation);
844 }
845
846 // We will loop until a) we manage to successfully perform the
847 // allocation or b) we successfully schedule a collection which
848 // fails to perform the allocation. b) is the only case when we'll
849 // return NULL.
850 HeapWord* result = NULL;
851 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
852 bool should_try_gc;
853 bool preventive_collection_required = false;
854 uint gc_count_before;
855
856
857 {
858 MutexLocker x(Heap_lock);
859
860 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
861 preventive_collection_required = policy()->preventive_collection_required((uint)size_in_regions);
862 if (!preventive_collection_required) {
863 // Given that humongous objects are not allocated in young
864 // regions, we'll first try to do the allocation without doing a
865 // collection hoping that there's enough space in the heap.
866 result = humongous_obj_allocate(word_size);
867 if (result != NULL) {
868 policy()->old_gen_alloc_tracker()->
869 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
870 return result;
871 }
872 }
873
874 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
875 // the GCLocker initiated GC has been performed and then retry. This includes
876 // the case when the GC Locker is not active but has not been performed.
877 should_try_gc = !GCLocker::needs_gc();
878 // Read the GC count while still holding the Heap_lock.
879 gc_count_before = total_collections();
880 }
881
882 if (should_try_gc) {
883 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
884 : GCCause::_g1_humongous_allocation;
885 bool succeeded;
886 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
887 if (result != NULL) {
888 assert(succeeded, "only way to get back a non-NULL result");
889 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
890 Thread::current()->name(), p2i(result));
891 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
892 policy()->old_gen_alloc_tracker()->
893 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
894 return result;
895 }
896
897 if (succeeded) {
898 // We successfully scheduled a collection which failed to allocate. No
899 // point in trying to allocate further. We'll just return NULL.
900 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
901 SIZE_FORMAT " words", Thread::current()->name(), word_size);
902 return NULL;
903 }
904 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
905 Thread::current()->name(), word_size);
906 } else {
907 // Failed to schedule a collection.
908 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
909 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
910 SIZE_FORMAT " words", Thread::current()->name(), word_size);
911 return NULL;
912 }
913 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
914 // The GCLocker is either active or the GCLocker initiated
915 // GC has not yet been performed. Stall until it is and
916 // then retry the allocation.
917 GCLocker::stall_until_clear();
918 gclocker_retry_count += 1;
919 }
920
921
922 // We can reach here if we were unsuccessful in scheduling a
923 // collection (because another thread beat us to it) or if we were
924 // stalled due to the GC locker. In either can we should retry the
925 // allocation attempt in case another thread successfully
926 // performed a collection and reclaimed enough space.
927 // Humongous object allocation always needs a lock, so we wait for the retry
928 // in the next iteration of the loop, unlike for the regular iteration case.
929 // Give a warning if we seem to be looping forever.
930
931 if ((QueuedAllocationWarningCount > 0) &&
932 (try_count % QueuedAllocationWarningCount == 0)) {
933 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
934 Thread::current()->name(), try_count, word_size);
935 }
936 }
937
938 ShouldNotReachHere();
939 return NULL;
940 }
941
942 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
943 bool expect_null_mutator_alloc_region) {
944 assert_at_safepoint_on_vm_thread();
945 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
946 "the current alloc region was unexpectedly found to be non-NULL");
947
948 if (!is_humongous(word_size)) {
949 return _allocator->attempt_allocation_locked(word_size);
950 } else {
951 HeapWord* result = humongous_obj_allocate(word_size);
952 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
953 collector_state()->set_initiate_conc_mark_if_possible(true);
954 }
955 return result;
956 }
957
958 ShouldNotReachHere();
959 }
960
961 class PostCompactionPrinterClosure: public HeapRegionClosure {
962 private:
963 G1HRPrinter* _hr_printer;
964 public:
965 bool do_heap_region(HeapRegion* hr) {
966 assert(!hr->is_young(), "not expecting to find young regions");
967 _hr_printer->post_compaction(hr);
968 return false;
969 }
970
971 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
972 : _hr_printer(hr_printer) { }
973 };
974
975 void G1CollectedHeap::print_heap_after_full_collection() {
976 // Post collection region logging.
977 // We should do this after we potentially resize the heap so
978 // that all the COMMIT / UNCOMMIT events are generated before
979 // the compaction events.
980 if (_hr_printer.is_active()) {
981 PostCompactionPrinterClosure cl(hr_printer());
982 heap_region_iterate(&cl);
983 }
984 }
985
986 bool G1CollectedHeap::abort_concurrent_cycle() {
987 // If we start the compaction before the CM threads finish
988 // scanning the root regions we might trip them over as we'll
989 // be moving objects / updating references. So let's wait until
990 // they are done. By telling them to abort, they should complete
991 // early.
992 _cm->root_regions()->abort();
993 _cm->root_regions()->wait_until_scan_finished();
994
995 // Disable discovery and empty the discovered lists
996 // for the CM ref processor.
997 _ref_processor_cm->disable_discovery();
998 _ref_processor_cm->abandon_partial_discovery();
999 _ref_processor_cm->verify_no_references_recorded();
1000
1001 // Abandon current iterations of concurrent marking and concurrent
1002 // refinement, if any are in progress.
1003 return concurrent_mark()->concurrent_cycle_abort();
1004 }
1005
1006 void G1CollectedHeap::prepare_heap_for_full_collection() {
1007 // Make sure we'll choose a new allocation region afterwards.
1008 _allocator->release_mutator_alloc_regions();
1009 _allocator->abandon_gc_alloc_regions();
1010
1011 // We may have added regions to the current incremental collection
1012 // set between the last GC or pause and now. We need to clear the
1013 // incremental collection set and then start rebuilding it afresh
1014 // after this full GC.
1015 abandon_collection_set(collection_set());
1016
1017 _hrm.remove_all_free_regions();
1018 }
1019
1020 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1021 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1022 assert_used_and_recalculate_used_equal(this);
1023 if (!VerifyBeforeGC) {
1024 return;
1025 }
1026 _verifier->verify_region_sets_optional();
1027 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1028 _verifier->verify_bitmap_clear(true /* above_tams_only */);
1029 }
1030
1031 void G1CollectedHeap::prepare_heap_for_mutators() {
1032 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1033 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1034 DEBUG_ONLY(MetaspaceUtils::verify();)
1035
1036 // Prepare heap for normal collections.
1037 assert(num_free_regions() == 0, "we should not have added any free regions");
1038 rebuild_region_sets(false /* free_list_only */);
1039 abort_refinement();
1040 resize_heap_if_necessary();
1041 uncommit_regions_if_necessary();
1042
1043 // Rebuild the code root lists for each region
1044 rebuild_code_roots();
1045
1046 // Purge code root memory
1047 purge_code_root_memory();
1048
1049 // Start a new incremental collection set for the next pause
1050 start_new_collection_set();
1051
1052 _allocator->init_mutator_alloc_regions();
1053
1054 // Post collection state updates.
1055 MetaspaceGC::compute_new_size();
1056 }
1057
1058 void G1CollectedHeap::abort_refinement() {
1059 if (_hot_card_cache->use_cache()) {
1060 _hot_card_cache->reset_hot_cache();
1061 }
1062
1063 // Discard all remembered set updates and reset refinement statistics.
1064 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1065 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1066 "DCQS should be empty");
1067 concurrent_refine()->get_and_reset_refinement_stats();
1068 }
1069
1070 void G1CollectedHeap::verify_after_full_collection() {
1071 if (!VerifyAfterGC) {
1072 return;
1073 }
1074 _hrm.verify_optional();
1075 _verifier->verify_region_sets_optional();
1076 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1077 _verifier->verify_bitmap_clear(false /* above_tams_only */);
1078
1079 // At this point there should be no regions in the
1080 // entire heap tagged as young.
1081 assert(check_young_list_empty(), "young list should be empty at this point");
1082
1083 // Note: since we've just done a full GC, concurrent
1084 // marking is no longer active. Therefore we need not
1085 // re-enable reference discovery for the CM ref processor.
1086 // That will be done at the start of the next marking cycle.
1087 // We also know that the STW processor should no longer
1088 // discover any new references.
1089 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1090 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1091 _ref_processor_stw->verify_no_references_recorded();
1092 _ref_processor_cm->verify_no_references_recorded();
1093 }
1094
1095 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1096 bool clear_all_soft_refs,
1097 bool do_maximal_compaction) {
1098 assert_at_safepoint_on_vm_thread();
1099
1100 if (GCLocker::check_active_before_gc()) {
1101 // Full GC was not completed.
1102 return false;
1103 }
1104
1105 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1106 soft_ref_policy()->should_clear_all_soft_refs();
1107
1108 G1FullGCMark gc_mark;
1109 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1110 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximal_compaction);
1111
1112 collector.prepare_collection();
1113 collector.collect();
1114 collector.complete_collection();
1115
1116 // Full collection was successfully completed.
1117 return true;
1118 }
1119
1120 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1121 // Currently, there is no facility in the do_full_collection(bool) API to notify
1122 // the caller that the collection did not succeed (e.g., because it was locked
1123 // out by the GC locker). So, right now, we'll ignore the return value.
1124 // When clear_all_soft_refs is set we want to do a maximal compaction
1125 // not leaving any dead wood.
1126 bool do_maximal_compaction = clear_all_soft_refs;
1127 bool dummy = do_full_collection(true, /* explicit_gc */
1128 clear_all_soft_refs,
1129 do_maximal_compaction);
1130 }
1131
1132 bool G1CollectedHeap::upgrade_to_full_collection() {
1133 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1134 log_info(gc, ergo)("Attempting full compaction clearing soft references");
1135 bool success = do_full_collection(false /* explicit gc */,
1136 true /* clear_all_soft_refs */,
1137 false /* do_maximal_compaction */);
1138 // do_full_collection only fails if blocked by GC locker and that can't
1139 // be the case here since we only call this when already completed one gc.
1140 assert(success, "invariant");
1141 return success;
1142 }
1143
1144 void G1CollectedHeap::resize_heap_if_necessary() {
1145 assert_at_safepoint_on_vm_thread();
1146
1147 bool should_expand;
1148 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1149
1150 if (resize_amount == 0) {
1151 return;
1152 } else if (should_expand) {
1153 expand(resize_amount, _workers);
1154 } else {
1155 shrink(resize_amount);
1156 }
1157 }
1158
1159 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1160 bool do_gc,
1161 bool maximal_compaction,
1162 bool expect_null_mutator_alloc_region,
1163 bool* gc_succeeded) {
1164 *gc_succeeded = true;
1165 // Let's attempt the allocation first.
1166 HeapWord* result =
1167 attempt_allocation_at_safepoint(word_size,
1168 expect_null_mutator_alloc_region);
1169 if (result != NULL) {
1170 return result;
1171 }
1172
1173 // In a G1 heap, we're supposed to keep allocation from failing by
1174 // incremental pauses. Therefore, at least for now, we'll favor
1175 // expansion over collection. (This might change in the future if we can
1176 // do something smarter than full collection to satisfy a failed alloc.)
1177 result = expand_and_allocate(word_size);
1178 if (result != NULL) {
1179 return result;
1180 }
1181
1182 if (do_gc) {
1183 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1184 // Expansion didn't work, we'll try to do a Full GC.
1185 // If maximal_compaction is set we clear all soft references and don't
1186 // allow any dead wood to be left on the heap.
1187 if (maximal_compaction) {
1188 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
1189 } else {
1190 log_info(gc, ergo)("Attempting full compaction");
1191 }
1192 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1193 maximal_compaction /* clear_all_soft_refs */ ,
1194 maximal_compaction /* do_maximal_compaction */);
1195 }
1196
1197 return NULL;
1198 }
1199
1200 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1201 bool* succeeded) {
1202 assert_at_safepoint_on_vm_thread();
1203
1204 // Attempts to allocate followed by Full GC.
1205 HeapWord* result =
1206 satisfy_failed_allocation_helper(word_size,
1207 true, /* do_gc */
1208 false, /* maximum_collection */
1209 false, /* expect_null_mutator_alloc_region */
1210 succeeded);
1211
1212 if (result != NULL || !*succeeded) {
1213 return result;
1214 }
1215
1216 // Attempts to allocate followed by Full GC that will collect all soft references.
1217 result = satisfy_failed_allocation_helper(word_size,
1218 true, /* do_gc */
1219 true, /* maximum_collection */
1220 true, /* expect_null_mutator_alloc_region */
1221 succeeded);
1222
1223 if (result != NULL || !*succeeded) {
1224 return result;
1225 }
1226
1227 // Attempts to allocate, no GC
1228 result = satisfy_failed_allocation_helper(word_size,
1229 false, /* do_gc */
1230 false, /* maximum_collection */
1231 true, /* expect_null_mutator_alloc_region */
1232 succeeded);
1233
1234 if (result != NULL) {
1235 return result;
1236 }
1237
1238 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1239 "Flag should have been handled and cleared prior to this point");
1240
1241 // What else? We might try synchronous finalization later. If the total
1242 // space available is large enough for the allocation, then a more
1243 // complete compaction phase than we've tried so far might be
1244 // appropriate.
1245 return NULL;
1246 }
1247
1248 // Attempting to expand the heap sufficiently
1249 // to support an allocation of the given "word_size". If
1250 // successful, perform the allocation and return the address of the
1251 // allocated block, or else "NULL".
1252
1253 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1254 assert_at_safepoint_on_vm_thread();
1255
1256 _verifier->verify_region_sets_optional();
1257
1258 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1259 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1260 word_size * HeapWordSize);
1261
1262
1263 if (expand(expand_bytes, _workers)) {
1264 _hrm.verify_optional();
1265 _verifier->verify_region_sets_optional();
1266 return attempt_allocation_at_safepoint(word_size,
1267 false /* expect_null_mutator_alloc_region */);
1268 }
1269 return NULL;
1270 }
1271
1272 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1273 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1274 aligned_expand_bytes = align_up(aligned_expand_bytes,
1275 HeapRegion::GrainBytes);
1276
1277 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1278 expand_bytes, aligned_expand_bytes);
1279
1280 if (is_maximal_no_gc()) {
1281 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1282 return false;
1283 }
1284
1285 double expand_heap_start_time_sec = os::elapsedTime();
1286 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1287 assert(regions_to_expand > 0, "Must expand by at least one region");
1288
1289 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1290 if (expand_time_ms != NULL) {
1291 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1292 }
1293
1294 if (expanded_by > 0) {
1295 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1296 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1297 policy()->record_new_heap_size(num_regions());
1298 } else {
1299 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1300
1301 // The expansion of the virtual storage space was unsuccessful.
1302 // Let's see if it was because we ran out of swap.
1303 if (G1ExitOnExpansionFailure &&
1304 _hrm.available() >= regions_to_expand) {
1305 // We had head room...
1306 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1307 }
1308 }
1309 return expanded_by > 0;
1310 }
1311
1312 bool G1CollectedHeap::expand_single_region(uint node_index) {
1313 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1314
1315 if (expanded_by == 0) {
1316 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1317 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1318 return false;
1319 }
1320
1321 policy()->record_new_heap_size(num_regions());
1322 return true;
1323 }
1324
1325 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1326 size_t aligned_shrink_bytes =
1327 ReservedSpace::page_align_size_down(shrink_bytes);
1328 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1329 HeapRegion::GrainBytes);
1330 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1331
1332 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1333 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1334
1335 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",
1336 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1337 if (num_regions_removed > 0) {
1338 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1339 policy()->record_new_heap_size(num_regions());
1340 } else {
1341 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1342 }
1343 }
1344
1345 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1346 _verifier->verify_region_sets_optional();
1347
1348 // We should only reach here at the end of a Full GC or during Remark which
1349 // means we should not not be holding to any GC alloc regions. The method
1350 // below will make sure of that and do any remaining clean up.
1351 _allocator->abandon_gc_alloc_regions();
1352
1353 // Instead of tearing down / rebuilding the free lists here, we
1354 // could instead use the remove_all_pending() method on free_list to
1355 // remove only the ones that we need to remove.
1356 _hrm.remove_all_free_regions();
1357 shrink_helper(shrink_bytes);
1358 rebuild_region_sets(true /* free_list_only */);
1359
1360 _hrm.verify_optional();
1361 _verifier->verify_region_sets_optional();
1362 }
1363
1364 class OldRegionSetChecker : public HeapRegionSetChecker {
1365 public:
1366 void check_mt_safety() {
1367 // Master Old Set MT safety protocol:
1368 // (a) If we're at a safepoint, operations on the master old set
1369 // should be invoked:
1370 // - by the VM thread (which will serialize them), or
1371 // - by the GC workers while holding the FreeList_lock, if we're
1372 // at a safepoint for an evacuation pause (this lock is taken
1373 // anyway when an GC alloc region is retired so that a new one
1374 // is allocated from the free list), or
1375 // - by the GC workers while holding the OldSets_lock, if we're at a
1376 // safepoint for a cleanup pause.
1377 // (b) If we're not at a safepoint, operations on the master old set
1378 // should be invoked while holding the Heap_lock.
1379
1380 if (SafepointSynchronize::is_at_safepoint()) {
1381 guarantee(Thread::current()->is_VM_thread() ||
1382 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1383 "master old set MT safety protocol at a safepoint");
1384 } else {
1385 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1386 }
1387 }
1388 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1389 const char* get_description() { return "Old Regions"; }
1390 };
1391
1392 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1393 public:
1394 void check_mt_safety() {
1395 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1396 "May only change archive regions during initialization or safepoint.");
1397 }
1398 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1399 const char* get_description() { return "Archive Regions"; }
1400 };
1401
1402 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1403 public:
1404 void check_mt_safety() {
1405 // Humongous Set MT safety protocol:
1406 // (a) If we're at a safepoint, operations on the master humongous
1407 // set should be invoked by either the VM thread (which will
1408 // serialize them) or by the GC workers while holding the
1409 // OldSets_lock.
1410 // (b) If we're not at a safepoint, operations on the master
1411 // humongous set should be invoked while holding the Heap_lock.
1412
1413 if (SafepointSynchronize::is_at_safepoint()) {
1414 guarantee(Thread::current()->is_VM_thread() ||
1415 OldSets_lock->owned_by_self(),
1416 "master humongous set MT safety protocol at a safepoint");
1417 } else {
1418 guarantee(Heap_lock->owned_by_self(),
1419 "master humongous set MT safety protocol outside a safepoint");
1420 }
1421 }
1422 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1423 const char* get_description() { return "Humongous Regions"; }
1424 };
1425
1426 G1CollectedHeap::G1CollectedHeap() :
1427 CollectedHeap(),
1428 _service_thread(NULL),
1429 _periodic_gc_task(NULL),
1430 _free_segmented_array_memory_task(NULL),
1431 _workers(NULL),
1432 _card_table(NULL),
1433 _collection_pause_end(Ticks::now()),
1434 _soft_ref_policy(),
1435 _old_set("Old Region Set", new OldRegionSetChecker()),
1436 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1437 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1438 _bot(NULL),
1439 _listener(),
1440 _numa(G1NUMA::create()),
1441 _hrm(),
1442 _allocator(NULL),
1443 _evac_failure_injector(),
1444 _verifier(NULL),
1445 _summary_bytes_used(0),
1446 _bytes_used_during_gc(0),
1447 _archive_allocator(nullptr),
1448 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1449 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1450 _monitoring_support(nullptr),
1451 _num_humongous_objects(0),
1452 _num_humongous_reclaim_candidates(0),
1453 _hr_printer(),
1454 _collector_state(),
1455 _old_marking_cycles_started(0),
1456 _old_marking_cycles_completed(0),
1457 _eden(),
1458 _survivor(),
1459 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1460 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1461 _policy(new G1Policy(_gc_timer_stw)),
1462 _heap_sizing_policy(NULL),
1463 _collection_set(this, _policy),
1464 _hot_card_cache(NULL),
1465 _rem_set(NULL),
1466 _card_set_config(),
1467 _cm(NULL),
1468 _cm_thread(NULL),
1469 _cr(NULL),
1470 _task_queues(NULL),
1471 _ref_processor_stw(NULL),
1472 _is_alive_closure_stw(this),
1473 _is_subject_to_discovery_stw(this),
1474 _ref_processor_cm(NULL),
1475 _is_alive_closure_cm(this),
1476 _is_subject_to_discovery_cm(this),
1477 _region_attr() {
1478
1479 _verifier = new G1HeapVerifier(this);
1480
1481 _allocator = new G1Allocator(this);
1482
1483 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1484
1485 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1486
1487 // Override the default _filler_array_max_size so that no humongous filler
1488 // objects are created.
1489 _filler_array_max_size = _humongous_object_threshold_in_words;
1490
1491 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1492 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1493
1494 uint n_queues = ParallelGCThreads;
1495 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1496
1497 for (uint i = 0; i < n_queues; i++) {
1498 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1499 _task_queues->register_queue(i, q);
1500 }
1501
1502 _gc_tracer_stw->initialize();
1503
1504 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1505 }
1506
1507 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1508 size_t size,
1509 size_t translation_factor) {
1510 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1511 // Allocate a new reserved space, preferring to use large pages.
1512 ReservedSpace rs(size, preferred_page_size);
1513 size_t page_size = rs.page_size();
1514 G1RegionToSpaceMapper* result =
1515 G1RegionToSpaceMapper::create_mapper(rs,
1516 size,
1517 page_size,
1518 HeapRegion::GrainBytes,
1519 translation_factor,
1520 mtGC);
1521
1522 os::trace_page_sizes_for_requested_size(description,
1523 size,
1524 page_size,
1525 preferred_page_size,
1526 rs.base(),
1527 rs.size());
1528
1529 return result;
1530 }
1531
1532 jint G1CollectedHeap::initialize_concurrent_refinement() {
1533 jint ecode = JNI_OK;
1534 _cr = G1ConcurrentRefine::create(&ecode);
1535 return ecode;
1536 }
1537
1538 jint G1CollectedHeap::initialize_service_thread() {
1539 _service_thread = new G1ServiceThread();
1540 if (_service_thread->osthread() == NULL) {
1541 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1542 return JNI_ENOMEM;
1543 }
1544 return JNI_OK;
1545 }
1546
1547 jint G1CollectedHeap::initialize() {
1548
1549 // Necessary to satisfy locking discipline assertions.
1550
1551 MutexLocker x(Heap_lock);
1552
1553 // While there are no constraints in the GC code that HeapWordSize
1554 // be any particular value, there are multiple other areas in the
1555 // system which believe this to be true (e.g. oop->object_size in some
1556 // cases incorrectly returns the size in wordSize units rather than
1557 // HeapWordSize).
1558 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1559
1560 size_t init_byte_size = InitialHeapSize;
1561 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1562
1563 // Ensure that the sizes are properly aligned.
1564 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1565 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1566 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1567
1568 // Reserve the maximum.
1569
1570 // When compressed oops are enabled, the preferred heap base
1571 // is calculated by subtracting the requested size from the
1572 // 32Gb boundary and using the result as the base address for
1573 // heap reservation. If the requested size is not aligned to
1574 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1575 // into the ReservedHeapSpace constructor) then the actual
1576 // base of the reserved heap may end up differing from the
1577 // address that was requested (i.e. the preferred heap base).
1578 // If this happens then we could end up using a non-optimal
1579 // compressed oops mode.
1580
1581 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1582 HeapAlignment);
1583
1584 initialize_reserved_region(heap_rs);
1585
1586 // Create the barrier set for the entire reserved region.
1587 G1CardTable* ct = new G1CardTable(heap_rs.region());
1588 ct->initialize();
1589 G1BarrierSet* bs = new G1BarrierSet(ct);
1590 bs->initialize();
1591 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1592 BarrierSet::set_barrier_set(bs);
1593 _card_table = ct;
1594
1595 {
1596 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1597 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1598 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1599 }
1600
1601 // Create the hot card cache.
1602 _hot_card_cache = new G1HotCardCache(this);
1603
1604 // Create space mappers.
1605 size_t page_size = heap_rs.page_size();
1606 G1RegionToSpaceMapper* heap_storage =
1607 G1RegionToSpaceMapper::create_mapper(heap_rs,
1608 heap_rs.size(),
1609 page_size,
1610 HeapRegion::GrainBytes,
1611 1,
1612 mtJavaHeap);
1613 if(heap_storage == NULL) {
1614 vm_shutdown_during_initialization("Could not initialize G1 heap");
1615 return JNI_ERR;
1616 }
1617
1618 os::trace_page_sizes("Heap",
1619 MinHeapSize,
1620 reserved_byte_size,
1621 page_size,
1622 heap_rs.base(),
1623 heap_rs.size());
1624 heap_storage->set_mapping_changed_listener(&_listener);
1625
1626 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmap.
1627 G1RegionToSpaceMapper* bot_storage =
1628 create_aux_memory_mapper("Block Offset Table",
1629 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1630 G1BlockOffsetTable::heap_map_factor());
1631
1632 G1RegionToSpaceMapper* cardtable_storage =
1633 create_aux_memory_mapper("Card Table",
1634 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1635 G1CardTable::heap_map_factor());
1636
1637 G1RegionToSpaceMapper* card_counts_storage =
1638 create_aux_memory_mapper("Card Counts Table",
1639 G1CardCounts::compute_size(heap_rs.size() / HeapWordSize),
1640 G1CardCounts::heap_map_factor());
1641
1642 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1643 G1RegionToSpaceMapper* bitmap_storage =
1644 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1645
1646 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1647 _card_table->initialize(cardtable_storage);
1648
1649 // Do later initialization work for concurrent refinement.
1650 _hot_card_cache->initialize(card_counts_storage);
1651
1652 // 6843694 - ensure that the maximum region index can fit
1653 // in the remembered set structures.
1654 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1655 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1656
1657 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1658 // start within the first card.
1659 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1660 G1FromCardCache::initialize(max_reserved_regions());
1661 // Also create a G1 rem set.
1662 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1663 _rem_set->initialize(max_reserved_regions());
1664
1665 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1666 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1667 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1668 "too many cards per region");
1669
1670 HeapRegionRemSet::initialize(_reserved);
1671
1672 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1673
1674 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1675
1676 {
1677 size_t granularity = HeapRegion::GrainBytes;
1678
1679 _region_attr.initialize(reserved(), granularity);
1680 }
1681
1682 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1683 if (_workers == NULL) {
1684 return JNI_ENOMEM;
1685 }
1686 _workers->initialize_workers();
1687
1688 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1689
1690 // Create the G1ConcurrentMark data structure and thread.
1691 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1692 _cm = new G1ConcurrentMark(this, bitmap_storage);
1693 _cm_thread = _cm->cm_thread();
1694
1695 // Now expand into the initial heap size.
1696 if (!expand(init_byte_size, _workers)) {
1697 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1698 return JNI_ENOMEM;
1699 }
1700
1701 // Perform any initialization actions delegated to the policy.
1702 policy()->init(this, &_collection_set);
1703
1704 jint ecode = initialize_concurrent_refinement();
1705 if (ecode != JNI_OK) {
1706 return ecode;
1707 }
1708
1709 ecode = initialize_service_thread();
1710 if (ecode != JNI_OK) {
1711 return ecode;
1712 }
1713
1714 // Initialize and schedule sampling task on service thread.
1715 _rem_set->initialize_sampling_task(service_thread());
1716
1717 // Create and schedule the periodic gc task on the service thread.
1718 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1719 _service_thread->register_task(_periodic_gc_task);
1720
1721 _free_segmented_array_memory_task = new G1SegmentedArrayFreeMemoryTask("Card Set Free Memory Task");
1722 _service_thread->register_task(_free_segmented_array_memory_task);
1723
1724 // Here we allocate the dummy HeapRegion that is required by the
1725 // G1AllocRegion class.
1726 HeapRegion* dummy_region = _hrm.get_dummy_region();
1727
1728 // We'll re-use the same region whether the alloc region will
1729 // require BOT updates or not and, if it doesn't, then a non-young
1730 // region will complain that it cannot support allocations without
1731 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1732 dummy_region->set_eden();
1733 // Make sure it's full.
1734 dummy_region->set_top(dummy_region->end());
1735 G1AllocRegion::setup(this, dummy_region);
1736
1737 _allocator->init_mutator_alloc_regions();
1738
1739 // Do create of the monitoring and management support so that
1740 // values in the heap have been properly initialized.
1741 _monitoring_support = new G1MonitoringSupport(this);
1742
1743 _collection_set.initialize(max_reserved_regions());
1744
1745 evac_failure_injector()->reset();
1746
1747 G1InitLogger::print();
1748
1749 return JNI_OK;
1750 }
1751
1752 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1753 return _cm_thread->should_terminate();
1754 }
1755
1756 void G1CollectedHeap::stop() {
1757 // Stop all concurrent threads. We do this to make sure these threads
1758 // do not continue to execute and access resources (e.g. logging)
1759 // that are destroyed during shutdown.
1760 _cr->stop();
1761 _service_thread->stop();
1762 _cm_thread->stop();
1763 }
1764
1765 void G1CollectedHeap::safepoint_synchronize_begin() {
1766 SuspendibleThreadSet::synchronize();
1767 }
1768
1769 void G1CollectedHeap::safepoint_synchronize_end() {
1770 SuspendibleThreadSet::desynchronize();
1771 }
1772
1773 void G1CollectedHeap::post_initialize() {
1774 CollectedHeap::post_initialize();
1775 ref_processing_init();
1776 }
1777
1778 void G1CollectedHeap::ref_processing_init() {
1779 // Reference processing in G1 currently works as follows:
1780 //
1781 // * There are two reference processor instances. One is
1782 // used to record and process discovered references
1783 // during concurrent marking; the other is used to
1784 // record and process references during STW pauses
1785 // (both full and incremental).
1786 // * Both ref processors need to 'span' the entire heap as
1787 // the regions in the collection set may be dotted around.
1788 //
1789 // * For the concurrent marking ref processor:
1790 // * Reference discovery is enabled at concurrent start.
1791 // * Reference discovery is disabled and the discovered
1792 // references processed etc during remarking.
1793 // * Reference discovery is MT (see below).
1794 // * Reference discovery requires a barrier (see below).
1795 // * Reference processing may or may not be MT
1796 // (depending on the value of ParallelRefProcEnabled
1797 // and ParallelGCThreads).
1798 // * A full GC disables reference discovery by the CM
1799 // ref processor and abandons any entries on it's
1800 // discovered lists.
1801 //
1802 // * For the STW processor:
1803 // * Non MT discovery is enabled at the start of a full GC.
1804 // * Processing and enqueueing during a full GC is non-MT.
1805 // * During a full GC, references are processed after marking.
1806 //
1807 // * Discovery (may or may not be MT) is enabled at the start
1808 // of an incremental evacuation pause.
1809 // * References are processed near the end of a STW evacuation pause.
1810 // * For both types of GC:
1811 // * Discovery is atomic - i.e. not concurrent.
1812 // * Reference discovery will not need a barrier.
1813
1814 // Concurrent Mark ref processor
1815 _ref_processor_cm =
1816 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1817 ParallelGCThreads, // degree of mt processing
1818 // We discover with the gc worker threads during Remark, so both
1819 // thread counts must be considered for discovery.
1820 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1821 true, // Reference discovery is concurrent
1822 &_is_alive_closure_cm); // is alive closure
1823
1824 // STW ref processor
1825 _ref_processor_stw =
1826 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1827 ParallelGCThreads, // degree of mt processing
1828 ParallelGCThreads, // degree of mt discovery
1829 false, // Reference discovery is not concurrent
1830 &_is_alive_closure_stw); // is alive closure
1831 }
1832
1833 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1834 return &_soft_ref_policy;
1835 }
1836
1837 size_t G1CollectedHeap::capacity() const {
1838 return _hrm.length() * HeapRegion::GrainBytes;
1839 }
1840
1841 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1842 return _hrm.total_free_bytes();
1843 }
1844
1845 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1846 _hot_card_cache->drain(cl, worker_id);
1847 }
1848
1849 // Computes the sum of the storage used by the various regions.
1850 size_t G1CollectedHeap::used() const {
1851 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1852 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
1853 return result;
1854 }
1855
1856 size_t G1CollectedHeap::used_unlocked() const {
1857 return _summary_bytes_used;
1858 }
1859
1860 class SumUsedClosure: public HeapRegionClosure {
1861 size_t _used;
1862 public:
1863 SumUsedClosure() : _used(0) {}
1864 bool do_heap_region(HeapRegion* r) {
1865 _used += r->used();
1866 return false;
1867 }
1868 size_t result() { return _used; }
1869 };
1870
1871 size_t G1CollectedHeap::recalculate_used() const {
1872 SumUsedClosure blk;
1873 heap_region_iterate(&blk);
1874 return blk.result();
1875 }
1876
1877 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1878 switch (cause) {
1879 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1880 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1881 case GCCause::_wb_conc_mark: return true;
1882 default : return false;
1883 }
1884 }
1885
1886 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1887 switch (cause) {
1888 case GCCause::_g1_humongous_allocation: return true;
1889 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1890 case GCCause::_wb_breakpoint: return true;
1891 case GCCause::_codecache_GC_threshold: return true;
1892 default: return is_user_requested_concurrent_full_gc(cause);
1893 }
1894 }
1895
1896 #ifndef PRODUCT
1897 void G1CollectedHeap::allocate_dummy_regions() {
1898 // Let's fill up most of the region
1899 size_t word_size = HeapRegion::GrainWords - 1024;
1900 // And as a result the region we'll allocate will be humongous.
1901 guarantee(is_humongous(word_size), "sanity");
1902
1903 // _filler_array_max_size is set to humongous object threshold
1904 // but temporarily change it to use CollectedHeap::fill_with_object().
1905 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1906
1907 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1908 // Let's use the existing mechanism for the allocation
1909 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1910 if (dummy_obj != NULL) {
1911 MemRegion mr(dummy_obj, word_size);
1912 CollectedHeap::fill_with_object(mr);
1913 } else {
1914 // If we can't allocate once, we probably cannot allocate
1915 // again. Let's get out of the loop.
1916 break;
1917 }
1918 }
1919 }
1920 #endif // !PRODUCT
1921
1922 void G1CollectedHeap::increment_old_marking_cycles_started() {
1923 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1924 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1925 "Wrong marking cycle count (started: %d, completed: %d)",
1926 _old_marking_cycles_started, _old_marking_cycles_completed);
1927
1928 _old_marking_cycles_started++;
1929 }
1930
1931 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1932 bool whole_heap_examined) {
1933 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1934
1935 // We assume that if concurrent == true, then the caller is a
1936 // concurrent thread that was joined the Suspendible Thread
1937 // Set. If there's ever a cheap way to check this, we should add an
1938 // assert here.
1939
1940 // Given that this method is called at the end of a Full GC or of a
1941 // concurrent cycle, and those can be nested (i.e., a Full GC can
1942 // interrupt a concurrent cycle), the number of full collections
1943 // completed should be either one (in the case where there was no
1944 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1945 // behind the number of full collections started.
1946
1947 // This is the case for the inner caller, i.e. a Full GC.
1948 assert(concurrent ||
1949 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1950 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1951 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1952 "is inconsistent with _old_marking_cycles_completed = %u",
1953 _old_marking_cycles_started, _old_marking_cycles_completed);
1954
1955 // This is the case for the outer caller, i.e. the concurrent cycle.
1956 assert(!concurrent ||
1957 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1958 "for outer caller (concurrent cycle): "
1959 "_old_marking_cycles_started = %u "
1960 "is inconsistent with _old_marking_cycles_completed = %u",
1961 _old_marking_cycles_started, _old_marking_cycles_completed);
1962
1963 _old_marking_cycles_completed += 1;
1964 if (whole_heap_examined) {
1965 // Signal that we have completed a visit to all live objects.
1966 record_whole_heap_examined_timestamp();
1967 }
1968
1969 // We need to clear the "in_progress" flag in the CM thread before
1970 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1971 // is set) so that if a waiter requests another System.gc() it doesn't
1972 // incorrectly see that a marking cycle is still in progress.
1973 if (concurrent) {
1974 _cm_thread->set_idle();
1975 }
1976
1977 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1978 // for a full GC to finish that their wait is over.
1979 ml.notify_all();
1980 }
1981
1982 // Helper for collect().
1983 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1984 MutexLocker ml(Heap_lock);
1985 return G1GCCounters(g1h);
1986 }
1987
1988 void G1CollectedHeap::collect(GCCause::Cause cause) {
1989 try_collect(cause, collection_counters(this));
1990 }
1991
1992 // Return true if (x < y) with allowance for wraparound.
1993 static bool gc_counter_less_than(uint x, uint y) {
1994 return (x - y) > (UINT_MAX/2);
1995 }
1996
1997 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1998 // Macro so msg printing is format-checked.
1999 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2000 do { \
2001 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2002 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2003 ResourceMark rm; /* For thread name. */ \
2004 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2005 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2006 Thread::current()->name(), \
2007 GCCause::to_string(cause)); \
2008 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2009 } \
2010 } while (0)
2011
2012 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2013 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2014
2015 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2016 uint gc_counter,
2017 uint old_marking_started_before) {
2018 assert_heap_not_locked();
2019 assert(should_do_concurrent_full_gc(cause),
2020 "Non-concurrent cause %s", GCCause::to_string(cause));
2021
2022 for (uint i = 1; true; ++i) {
2023 // Try to schedule concurrent start evacuation pause that will
2024 // start a concurrent cycle.
2025 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2026 VM_G1TryInitiateConcMark op(gc_counter,
2027 cause,
2028 policy()->max_pause_time_ms());
2029 VMThread::execute(&op);
2030
2031 // Request is trivially finished.
2032 if (cause == GCCause::_g1_periodic_collection) {
2033 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2034 return op.gc_succeeded();
2035 }
2036
2037 // If VMOp skipped initiating concurrent marking cycle because
2038 // we're terminating, then we're done.
2039 if (op.terminating()) {
2040 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2041 return false;
2042 }
2043
2044 // Lock to get consistent set of values.
2045 uint old_marking_started_after;
2046 uint old_marking_completed_after;
2047 {
2048 MutexLocker ml(Heap_lock);
2049 // Update gc_counter for retrying VMOp if needed. Captured here to be
2050 // consistent with the values we use below for termination tests. If
2051 // a retry is needed after a possible wait, and another collection
2052 // occurs in the meantime, it will cause our retry to be skipped and
2053 // we'll recheck for termination with updated conditions from that
2054 // more recent collection. That's what we want, rather than having
2055 // our retry possibly perform an unnecessary collection.
2056 gc_counter = total_collections();
2057 old_marking_started_after = _old_marking_cycles_started;
2058 old_marking_completed_after = _old_marking_cycles_completed;
2059 }
2060
2061 if (cause == GCCause::_wb_breakpoint) {
2062 if (op.gc_succeeded()) {
2063 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2064 return true;
2065 }
2066 // When _wb_breakpoint there can't be another cycle or deferred.
2067 assert(!op.cycle_already_in_progress(), "invariant");
2068 assert(!op.whitebox_attached(), "invariant");
2069 // Concurrent cycle attempt might have been cancelled by some other
2070 // collection, so retry. Unlike other cases below, we want to retry
2071 // even if cancelled by a STW full collection, because we really want
2072 // to start a concurrent cycle.
2073 if (old_marking_started_before != old_marking_started_after) {
2074 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2075 old_marking_started_before = old_marking_started_after;
2076 }
2077 } else if (!GCCause::is_user_requested_gc(cause)) {
2078 // For an "automatic" (not user-requested) collection, we just need to
2079 // ensure that progress is made.
2080 //
2081 // Request is finished if any of
2082 // (1) the VMOp successfully performed a GC,
2083 // (2) a concurrent cycle was already in progress,
2084 // (3) whitebox is controlling concurrent cycles,
2085 // (4) a new cycle was started (by this thread or some other), or
2086 // (5) a Full GC was performed.
2087 // Cases (4) and (5) are detected together by a change to
2088 // _old_marking_cycles_started.
2089 //
2090 // Note that (1) does not imply (4). If we're still in the mixed
2091 // phase of an earlier concurrent collection, the request to make the
2092 // collection a concurrent start won't be honored. If we don't check for
2093 // both conditions we'll spin doing back-to-back collections.
2094 if (op.gc_succeeded() ||
2095 op.cycle_already_in_progress() ||
2096 op.whitebox_attached() ||
2097 (old_marking_started_before != old_marking_started_after)) {
2098 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2099 return true;
2100 }
2101 } else { // User-requested GC.
2102 // For a user-requested collection, we want to ensure that a complete
2103 // full collection has been performed before returning, but without
2104 // waiting for more than needed.
2105
2106 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2107 // new cycle was started. That's good, because it's not clear what we
2108 // should do otherwise. Trying again just does back to back GCs.
2109 // Can't wait for someone else to start a cycle. And returning fails
2110 // to meet the goal of ensuring a full collection was performed.
2111 assert(!op.gc_succeeded() ||
2112 (old_marking_started_before != old_marking_started_after),
2113 "invariant: succeeded %s, started before %u, started after %u",
2114 BOOL_TO_STR(op.gc_succeeded()),
2115 old_marking_started_before, old_marking_started_after);
2116
2117 // Request is finished if a full collection (concurrent or stw)
2118 // was started after this request and has completed, e.g.
2119 // started_before < completed_after.
2120 if (gc_counter_less_than(old_marking_started_before,
2121 old_marking_completed_after)) {
2122 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2123 return true;
2124 }
2125
2126 if (old_marking_started_after != old_marking_completed_after) {
2127 // If there is an in-progress cycle (possibly started by us), then
2128 // wait for that cycle to complete, e.g.
2129 // while completed_now < started_after.
2130 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2131 MonitorLocker ml(G1OldGCCount_lock);
2132 while (gc_counter_less_than(_old_marking_cycles_completed,
2133 old_marking_started_after)) {
2134 ml.wait();
2135 }
2136 // Request is finished if the collection we just waited for was
2137 // started after this request.
2138 if (old_marking_started_before != old_marking_started_after) {
2139 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2140 return true;
2141 }
2142 }
2143
2144 // If VMOp was successful then it started a new cycle that the above
2145 // wait &etc should have recognized as finishing this request. This
2146 // differs from a non-user-request, where gc_succeeded does not imply
2147 // a new cycle was started.
2148 assert(!op.gc_succeeded(), "invariant");
2149
2150 if (op.cycle_already_in_progress()) {
2151 // If VMOp failed because a cycle was already in progress, it
2152 // is now complete. But it didn't finish this user-requested
2153 // GC, so try again.
2154 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2155 continue;
2156 } else if (op.whitebox_attached()) {
2157 // If WhiteBox wants control, wait for notification of a state
2158 // change in the controller, then try again. Don't wait for
2159 // release of control, since collections may complete while in
2160 // control. Note: This won't recognize a STW full collection
2161 // while waiting; we can't wait on multiple monitors.
2162 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2163 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2164 if (ConcurrentGCBreakpoints::is_controlled()) {
2165 ml.wait();
2166 }
2167 continue;
2168 }
2169 }
2170
2171 // Collection failed and should be retried.
2172 assert(op.transient_failure(), "invariant");
2173
2174 if (GCLocker::is_active_and_needs_gc()) {
2175 // If GCLocker is active, wait until clear before retrying.
2176 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2177 GCLocker::stall_until_clear();
2178 }
2179
2180 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2181 }
2182 }
2183
2184 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
2185 const G1GCCounters& counters_before) {
2186 if (should_do_concurrent_full_gc(cause)) {
2187 return try_collect_concurrently(cause,
2188 counters_before.total_collections(),
2189 counters_before.old_marking_cycles_started());
2190 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
2191 // Indicate failure to be consistent with VMOp failure due to
2192 // another collection slipping in after our gc_count but before
2193 // our request is processed.
2194 return false;
2195 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2196 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2197
2198 // Schedule a standard evacuation pause. We're setting word_size
2199 // to 0 which means that we are not requesting a post-GC allocation.
2200 VM_G1CollectForAllocation op(0, /* word_size */
2201 counters_before.total_collections(),
2202 cause,
2203 policy()->max_pause_time_ms());
2204 VMThread::execute(&op);
2205 return op.gc_succeeded();
2206 } else {
2207 // Schedule a Full GC.
2208 VM_G1CollectFull op(counters_before.total_collections(),
2209 counters_before.total_full_collections(),
2210 cause);
2211 VMThread::execute(&op);
2212 return op.gc_succeeded();
2213 }
2214 }
2215
2216 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
2217 GCCauseSetter x(this, gc_cause);
2218
2219 // At this point we are supposed to start a concurrent cycle. We
2220 // will do so if one is not already in progress.
2221 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
2222 if (should_start) {
2223 double pause_target = policy()->max_pause_time_ms();
2224 do_collection_pause_at_safepoint(pause_target);
2225 }
2226 }
2227
2228 bool G1CollectedHeap::is_in(const void* p) const {
2229 return is_in_reserved(p) && _hrm.is_available(addr_to_region((HeapWord*)p));
2230 }
2231
2232 // Iteration functions.
2233
2234 // Iterates an ObjectClosure over all objects within a HeapRegion.
2235
2236 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2237 ObjectClosure* _cl;
2238 public:
2239 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2240 bool do_heap_region(HeapRegion* r) {
2241 if (!r->is_continues_humongous()) {
2242 r->object_iterate(_cl);
2243 }
2244 return false;
2245 }
2246 };
2247
2248 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2249 IterateObjectClosureRegionClosure blk(cl);
2250 heap_region_iterate(&blk);
2251 }
2252
2253 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2254 private:
2255 G1CollectedHeap* _heap;
2256 HeapRegionClaimer _claimer;
2257
2258 public:
2259 G1ParallelObjectIterator(uint thread_num) :
2260 _heap(G1CollectedHeap::heap()),
2261 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2262
2263 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2264 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2265 }
2266 };
2267
2268 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2269 return new G1ParallelObjectIterator(thread_num);
2270 }
2271
2272 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2273 IterateObjectClosureRegionClosure blk(cl);
2274 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2275 }
2276
2277 void G1CollectedHeap::keep_alive(oop obj) {
2278 G1BarrierSet::enqueue_preloaded(obj);
2279 }
2280
2281 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2282 _hrm.iterate(cl);
2283 }
2284
2285 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2286 HeapRegionClaimer *hrclaimer,
2287 uint worker_id) const {
2288 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2289 }
2290
2291 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2292 HeapRegionClaimer *hrclaimer) const {
2293 _hrm.par_iterate(cl, hrclaimer, 0);
2294 }
2295
2296 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2297 _collection_set.iterate(cl);
2298 }
2299
2300 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2301 HeapRegionClaimer* hr_claimer,
2302 uint worker_id) {
2303 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2304 }
2305
2306 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2307 HeapRegionClaimer* hr_claimer,
2308 uint worker_id) {
2309 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2310 }
2311
2312 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2313 HeapRegionClaimer* hr_claimer,
2314 const uint regions[],
2315 size_t length,
2316 uint worker_id) const {
2317 assert_at_safepoint();
2318 if (length == 0) {
2319 return;
2320 }
2321 uint total_workers = workers()->active_workers();
2322
2323 size_t start_pos = (worker_id * length) / total_workers;
2324 size_t cur_pos = start_pos;
2325
2326 do {
2327 uint region_idx = regions[cur_pos];
2328 if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) {
2329 HeapRegion* r = region_at(region_idx);
2330 bool result = cl->do_heap_region(r);
2331 guarantee(!result, "Must not cancel iteration");
2332 }
2333
2334 cur_pos++;
2335 if (cur_pos == length) {
2336 cur_pos = 0;
2337 }
2338 } while (cur_pos != start_pos);
2339 }
2340
2341 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2342 HeapRegion* hr = heap_region_containing(addr);
2343 // The CollectedHeap API requires us to not fail for any given address within
2344 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2345 // outside of the allocated area.
2346 if (addr >= hr->top()) {
2347 return nullptr;
2348 }
2349 return hr->block_start(addr);
2350 }
2351
2352 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2353 HeapRegion* hr = heap_region_containing(addr);
2354 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2355 }
2356
2357 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2358 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2359 }
2360
2361 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2362 return _eden.length() * HeapRegion::GrainBytes;
2363 }
2364
2365 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2366 // must be equal to the humongous object limit.
2367 size_t G1CollectedHeap::max_tlab_size() const {
2368 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2369 }
2370
2371 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2372 return _allocator->unsafe_max_tlab_alloc();
2373 }
2374
2375 size_t G1CollectedHeap::max_capacity() const {
2376 return max_regions() * HeapRegion::GrainBytes;
2377 }
2378
2379 void G1CollectedHeap::prepare_for_verify() {
2380 _verifier->prepare_for_verify();
2381 }
2382
2383 void G1CollectedHeap::verify(VerifyOption vo) {
2384 _verifier->verify(vo);
2385 }
2386
2387 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2388 return true;
2389 }
2390
2391 bool G1CollectedHeap::is_archived_object(oop object) const {
2392 return object != NULL && heap_region_containing(object)->is_archive();
2393 }
2394
2395 class PrintRegionClosure: public HeapRegionClosure {
2396 outputStream* _st;
2397 public:
2398 PrintRegionClosure(outputStream* st) : _st(st) {}
2399 bool do_heap_region(HeapRegion* r) {
2400 r->print_on(_st);
2401 return false;
2402 }
2403 };
2404
2405 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2406 const HeapRegion* hr,
2407 const VerifyOption vo) const {
2408 switch (vo) {
2409 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2410 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2411 default: ShouldNotReachHere();
2412 }
2413 return false; // keep some compilers happy
2414 }
2415
2416 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2417 const VerifyOption vo) const {
2418 switch (vo) {
2419 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2420 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2421 default: ShouldNotReachHere();
2422 }
2423 return false; // keep some compilers happy
2424 }
2425
2426 void G1CollectedHeap::print_heap_regions() const {
2427 LogTarget(Trace, gc, heap, region) lt;
2428 if (lt.is_enabled()) {
2429 LogStream ls(lt);
2430 print_regions_on(&ls);
2431 }
2432 }
2433
2434 void G1CollectedHeap::print_on(outputStream* st) const {
2435 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2436 st->print(" %-20s", "garbage-first heap");
2437 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2438 capacity()/K, heap_used/K);
2439 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2440 p2i(_hrm.reserved().start()),
2441 p2i(_hrm.reserved().end()));
2442 st->cr();
2443 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2444 uint young_regions = young_regions_count();
2445 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2446 (size_t) young_regions * HeapRegion::GrainBytes / K);
2447 uint survivor_regions = survivor_regions_count();
2448 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2449 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2450 st->cr();
2451 if (_numa->is_enabled()) {
2452 uint num_nodes = _numa->num_active_nodes();
2453 st->print(" remaining free region(s) on each NUMA node: ");
2454 const int* node_ids = _numa->node_ids();
2455 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2456 uint num_free_regions = _hrm.num_free_regions(node_index);
2457 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2458 }
2459 st->cr();
2460 }
2461 MetaspaceUtils::print_on(st);
2462 }
2463
2464 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2465 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2466 "HS=humongous(starts), HC=humongous(continues), "
2467 "CS=collection set, F=free, "
2468 "OA=open archive, CA=closed archive, "
2469 "TAMS=top-at-mark-start, "
2470 "PB=parsable bottom");
2471 PrintRegionClosure blk(st);
2472 heap_region_iterate(&blk);
2473 }
2474
2475 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2476 print_on(st);
2477
2478 // Print the per-region information.
2479 st->cr();
2480 print_regions_on(st);
2481 }
2482
2483 void G1CollectedHeap::print_on_error(outputStream* st) const {
2484 this->CollectedHeap::print_on_error(st);
2485
2486 if (_cm != NULL) {
2487 st->cr();
2488 _cm->print_on_error(st);
2489 }
2490 }
2491
2492 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2493 workers()->threads_do(tc);
2494 tc->do_thread(_cm_thread);
2495 _cm->threads_do(tc);
2496 _cr->threads_do(tc);
2497 tc->do_thread(_service_thread);
2498 }
2499
2500 void G1CollectedHeap::print_tracing_info() const {
2501 rem_set()->print_summary_info();
2502 concurrent_mark()->print_summary_info();
2503 }
2504
2505 #ifndef PRODUCT
2506 // Helpful for debugging RSet issues.
2507
2508 class PrintRSetsClosure : public HeapRegionClosure {
2509 private:
2510 const char* _msg;
2511 size_t _occupied_sum;
2512
2513 public:
2514 bool do_heap_region(HeapRegion* r) {
2515 HeapRegionRemSet* hrrs = r->rem_set();
2516 size_t occupied = hrrs->occupied();
2517 _occupied_sum += occupied;
2518
2519 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2520 if (occupied == 0) {
2521 tty->print_cr(" RSet is empty");
2522 } else {
2523 hrrs->print();
2524 }
2525 tty->print_cr("----------");
2526 return false;
2527 }
2528
2529 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2530 tty->cr();
2531 tty->print_cr("========================================");
2532 tty->print_cr("%s", msg);
2533 tty->cr();
2534 }
2535
2536 ~PrintRSetsClosure() {
2537 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2538 tty->print_cr("========================================");
2539 tty->cr();
2540 }
2541 };
2542
2543 void G1CollectedHeap::print_cset_rsets() {
2544 PrintRSetsClosure cl("Printing CSet RSets");
2545 collection_set_iterate_all(&cl);
2546 }
2547
2548 void G1CollectedHeap::print_all_rsets() {
2549 PrintRSetsClosure cl("Printing All RSets");;
2550 heap_region_iterate(&cl);
2551 }
2552 #endif // PRODUCT
2553
2554 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2555 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2556 }
2557
2558 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2559
2560 size_t eden_used_bytes = _eden.used_bytes();
2561 size_t survivor_used_bytes = _survivor.used_bytes();
2562 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2563
2564 size_t eden_capacity_bytes =
2565 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2566
2567 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2568 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2569 eden_capacity_bytes, survivor_used_bytes, num_regions());
2570 }
2571
2572 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2573 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2574 stats->unused(), stats->used(), stats->region_end_waste(),
2575 stats->regions_filled(), stats->direct_allocated(),
2576 stats->failure_used(), stats->failure_waste());
2577 }
2578
2579 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2580 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2581 gc_tracer->report_gc_heap_summary(when, heap_summary);
2582
2583 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2584 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2585 }
2586
2587 void G1CollectedHeap::gc_prologue(bool full) {
2588 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2589
2590 // Update common counters.
2591 increment_total_collections(full /* full gc */);
2592 if (full || collector_state()->in_concurrent_start_gc()) {
2593 increment_old_marking_cycles_started();
2594 }
2595 }
2596
2597 void G1CollectedHeap::gc_epilogue(bool full) {
2598 // Update common counters.
2599 if (full) {
2600 // Update the number of full collections that have been completed.
2601 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2602 }
2603
2604 #if COMPILER2_OR_JVMCI
2605 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2606 #endif
2607
2608 // We have just completed a GC. Update the soft reference
2609 // policy with the new heap occupancy
2610 Universe::heap()->update_capacity_and_used_at_gc();
2611
2612 _collection_pause_end = Ticks::now();
2613
2614 _free_segmented_array_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2615 &_collection_set_candidates_card_set_stats);
2616 }
2617
2618 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2619 return _hrm.uncommit_inactive_regions(region_limit);
2620 }
2621
2622 bool G1CollectedHeap::has_uncommittable_regions() {
2623 return _hrm.has_inactive_regions();
2624 }
2625
2626 void G1CollectedHeap::uncommit_regions_if_necessary() {
2627 if (has_uncommittable_regions()) {
2628 G1UncommitRegionTask::enqueue();
2629 }
2630 }
2631
2632 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2633 LogTarget(Trace, gc, heap, verify) lt;
2634
2635 if (lt.is_enabled()) {
2636 LogStream ls(lt);
2637 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2638 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2639 heap_region_iterate(&cl);
2640 }
2641 }
2642
2643 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2644 uint gc_count_before,
2645 bool* succeeded,
2646 GCCause::Cause gc_cause) {
2647 assert_heap_not_locked_and_not_at_safepoint();
2648 VM_G1CollectForAllocation op(word_size,
2649 gc_count_before,
2650 gc_cause,
2651 policy()->max_pause_time_ms());
2652 VMThread::execute(&op);
2653
2654 HeapWord* result = op.result();
2655 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2656 assert(result == NULL || ret_succeeded,
2657 "the result should be NULL if the VM did not succeed");
2658 *succeeded = ret_succeeded;
2659
2660 assert_heap_not_locked();
2661 return result;
2662 }
2663
2664 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2665 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2666
2667 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2668 if (concurrent_operation_is_full_mark) {
2669 _cm->post_concurrent_mark_start();
2670 _cm_thread->start_full_mark();
2671 } else {
2672 _cm->post_concurrent_undo_start();
2673 _cm_thread->start_undo_mark();
2674 }
2675 CGC_lock->notify();
2676 }
2677
2678 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2679 // We don't nominate objects with many remembered set entries, on
2680 // the assumption that such objects are likely still live.
2681 HeapRegionRemSet* rem_set = r->rem_set();
2682
2683 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2684 }
2685
2686 #ifndef PRODUCT
2687 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2688 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2689 public:
2690 virtual bool do_heap_region(HeapRegion* r) {
2691 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2692 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2693 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2694 "Region %u remset tracking status (%s) different to region attribute (%s)",
2695 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2696 return false;
2697 }
2698 } cl;
2699 heap_region_iterate(&cl);
2700 }
2701 #endif
2702
2703 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2704 public:
2705 bool do_heap_region(HeapRegion* hr) {
2706 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2707 hr->verify_rem_set();
2708 }
2709 return false;
2710 }
2711 };
2712
2713 void G1CollectedHeap::start_new_collection_set() {
2714 double start = os::elapsedTime();
2715
2716 collection_set()->start_incremental_building();
2717
2718 clear_region_attr();
2719
2720 guarantee(_eden.length() == 0, "eden should have been cleared");
2721 policy()->transfer_survivors_to_cset(survivor());
2722
2723 // We redo the verification but now wrt to the new CSet which
2724 // has just got initialized after the previous CSet was freed.
2725 _cm->verify_no_collection_set_oops();
2726
2727 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2728 }
2729
2730 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2731 if (collector_state()->in_concurrent_start_gc()) {
2732 return G1HeapVerifier::G1VerifyConcurrentStart;
2733 } else if (collector_state()->in_young_only_phase()) {
2734 return G1HeapVerifier::G1VerifyYoungNormal;
2735 } else {
2736 return G1HeapVerifier::G1VerifyMixed;
2737 }
2738 }
2739
2740 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2741 if (!VerifyBeforeGC) {
2742 return;
2743 }
2744 Ticks start = Ticks::now();
2745 _verifier->prepare_for_verify();
2746 _verifier->verify_region_sets_optional();
2747 _verifier->verify_dirty_young_regions();
2748 if (VerifyRememberedSets) {
2749 log_info(gc, verify)("[Verifying RemSets before GC]");
2750 VerifyRegionRemSetClosure v_cl;
2751 heap_region_iterate(&v_cl);
2752 }
2753 _verifier->verify_before_gc(type);
2754 verify_numa_regions("GC Start");
2755 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2756 }
2757
2758 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2759 if (!VerifyAfterGC) {
2760 return;
2761 }
2762 Ticks start = Ticks::now();
2763 if (VerifyRememberedSets) {
2764 log_info(gc, verify)("[Verifying RemSets after GC]");
2765 VerifyRegionRemSetClosure v_cl;
2766 heap_region_iterate(&v_cl);
2767 }
2768 _verifier->verify_after_gc(type);
2769 verify_numa_regions("GC End");
2770 _verifier->verify_region_sets_optional();
2771 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2772 }
2773
2774 void G1CollectedHeap::expand_heap_after_young_collection(){
2775 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2776 if (expand_bytes > 0) {
2777 // No need for an ergo logging here,
2778 // expansion_amount() does this when it returns a value > 0.
2779 double expand_ms = 0.0;
2780 if (!expand(expand_bytes, _workers, &expand_ms)) {
2781 // We failed to expand the heap. Cannot do anything about it.
2782 }
2783 phase_times()->record_expand_heap_time(expand_ms);
2784 }
2785 }
2786
2787 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2788 assert_at_safepoint_on_vm_thread();
2789 guarantee(!is_gc_active(), "collection is not reentrant");
2790
2791 if (GCLocker::check_active_before_gc()) {
2792 return false;
2793 }
2794
2795 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2796 return true;
2797 }
2798
2799 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2800 // This summary needs to be printed before incrementing total collections.
2801 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2802 _g1h->total_collections(),
2803 true /* show_thread_times */);
2804 _g1h->print_heap_before_gc();
2805 _g1h->print_heap_regions();
2806 }
2807
2808 G1HeapPrinterMark::~G1HeapPrinterMark() {
2809 _g1h->policy()->print_age_table();
2810 _g1h->rem_set()->print_coarsen_stats();
2811 // We are at the end of the GC. Total collections has already been increased.
2812 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2813 _g1h->total_collections() - 1,
2814 false /* show_thread_times */);
2815
2816 _heap_transition.print();
2817 _g1h->print_heap_regions();
2818 _g1h->print_heap_after_gc();
2819 // Print NUMA statistics.
2820 _g1h->numa()->print_statistics();
2821 }
2822
2823 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2824 _timer(timer), _tracer(tracer) {
2825
2826 _timer->register_gc_start();
2827 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2828 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2829 }
2830
2831 G1JFRTracerMark::~G1JFRTracerMark() {
2832 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2833 _timer->register_gc_end();
2834 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2835 }
2836
2837 void G1CollectedHeap::prepare_tlabs_for_mutator() {
2838 Ticks start = Ticks::now();
2839
2840 _survivor_evac_stats.adjust_desired_plab_sz();
2841 _old_evac_stats.adjust_desired_plab_sz();
2842
2843 allocate_dummy_regions();
2844
2845 _allocator->init_mutator_alloc_regions();
2846
2847 resize_all_tlabs();
2848
2849 phase_times()->record_resize_tlab_time_ms((Ticks::now() - start).seconds() * 1000.0);
2850 }
2851
2852 void G1CollectedHeap::retire_tlabs() {
2853 ensure_parsability(true);
2854 }
2855
2856 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2857 ResourceMark rm;
2858
2859 IsGCActiveMark active_gc_mark;
2860 GCIdMark gc_id_mark;
2861 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2862
2863 GCTraceCPUTime tcpu;
2864
2865 _bytes_used_during_gc = 0;
2866
2867 policy()->decide_on_concurrent_start_pause();
2868 // Record whether this pause may need to trigger a concurrent operation. Later,
2869 // when we signal the G1ConcurrentMarkThread, the collector state has already
2870 // been reset for the next pause.
2871 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2872
2873 // Perform the collection.
2874 G1YoungCollector collector(gc_cause(), target_pause_time_ms);
2875 collector.collect();
2876
2877 // It should now be safe to tell the concurrent mark thread to start
2878 // without its logging output interfering with the logging output
2879 // that came from the pause.
2880 if (should_start_concurrent_mark_operation) {
2881 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2882 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2883 // thread(s) could be running concurrently with us. Make sure that anything
2884 // after this point does not assume that we are the only GC thread running.
2885 // Note: of course, the actual marking work will not start until the safepoint
2886 // itself is released in SuspendibleThreadSet::desynchronize().
2887 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2888 ConcurrentGCBreakpoints::notify_idle_to_active();
2889 }
2890 }
2891
2892 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
2893 bool class_unloading_occurred) {
2894 uint num_workers = workers()->active_workers();
2895 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred);
2896 workers()->run_task(&unlink_task);
2897 }
2898
2899 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2900 assert(obj != NULL, "must not be NULL");
2901 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2902 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2903 // may falsely indicate that this is not the case here: however the collection set only
2904 // contains old regions when concurrent mark is not running.
2905 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2906 }
2907
2908 void G1CollectedHeap::make_pending_list_reachable() {
2909 if (collector_state()->in_concurrent_start_gc()) {
2910 oop pll_head = Universe::reference_pending_list();
2911 if (pll_head != NULL) {
2912 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2913 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2914 }
2915 }
2916 }
2917
2918 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2919 _num_humongous_objects = num_humongous_total;
2920 _num_humongous_reclaim_candidates = num_humongous_candidates;
2921 }
2922
2923 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2924 G1CollectionSetCandidates* candidates = G1CollectedHeap::heap()->collection_set()->candidates();
2925 return candidates != NULL && candidates->num_remaining() > 0;
2926 }
2927
2928 void G1CollectedHeap::set_collection_set_candidates_stats(G1SegmentedArrayMemoryStats& stats) {
2929 _collection_set_candidates_card_set_stats = stats;
2930 }
2931
2932 void G1CollectedHeap::set_young_gen_card_set_stats(const G1SegmentedArrayMemoryStats& stats) {
2933 _young_gen_card_set_stats = stats;
2934 }
2935
2936 void G1CollectedHeap::record_obj_copy_mem_stats() {
2937 policy()->old_gen_alloc_tracker()->
2938 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2939
2940 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2941 create_g1_evac_summary(&_old_evac_stats));
2942 }
2943
2944 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2945 concurrent_mark()->clear_bitmap_for_region(hr);
2946 }
2947
2948 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2949 assert(!hr->is_free(), "the region should not be free");
2950 assert(!hr->is_empty(), "the region should not be empty");
2951 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2952
2953 // Clear the card counts for this region.
2954 // Note: we only need to do this if the region is not young
2955 // (since we don't refine cards in young regions).
2956 if (!hr->is_young()) {
2957 _hot_card_cache->reset_card_counts(hr);
2958 }
2959
2960 // Reset region metadata to allow reuse.
2961 hr->hr_clear(true /* clear_space */);
2962 _policy->remset_tracker()->update_at_free(hr);
2963
2964 if (free_list != NULL) {
2965 free_list->add_ordered(hr);
2966 }
2967 }
2968
2969 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2970 FreeRegionList* free_list) {
2971 assert(hr->is_humongous(), "this is only for humongous regions");
2972 hr->clear_humongous();
2973 free_region(hr, free_list);
2974 }
2975
2976 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2977 const uint archive_regions_removed,
2978 const uint humongous_regions_removed) {
2979 if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) {
2980 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2981 _old_set.bulk_remove(old_regions_removed);
2982 _archive_set.bulk_remove(archive_regions_removed);
2983 _humongous_set.bulk_remove(humongous_regions_removed);
2984 }
2985
2986 }
2987
2988 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2989 assert(list != NULL, "list can't be null");
2990 if (!list->is_empty()) {
2991 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2992 _hrm.insert_list_into_free_list(list);
2993 }
2994 }
2995
2996 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2997 decrease_used(bytes);
2998 }
2999
3000 void G1CollectedHeap::clear_eden() {
3001 _eden.clear();
3002 }
3003
3004 void G1CollectedHeap::clear_collection_set() {
3005 collection_set()->clear();
3006 }
3007
3008 void G1CollectedHeap::rebuild_free_region_list() {
3009 Ticks start = Ticks::now();
3010 _hrm.rebuild_free_list(workers());
3011 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
3012 }
3013
3014 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
3015 public:
3016 virtual bool do_heap_region(HeapRegion* r) {
3017 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
3018 G1CollectedHeap::heap()->clear_region_attr(r);
3019 r->clear_young_index_in_cset();
3020 return false;
3021 }
3022 };
3023
3024 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
3025 G1AbandonCollectionSetClosure cl;
3026 collection_set_iterate_all(&cl);
3027
3028 collection_set->clear();
3029 collection_set->stop_incremental_building();
3030 }
3031
3032 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
3033 return _allocator->is_retained_old_region(hr);
3034 }
3035
3036 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
3037 _eden.add(hr);
3038 _policy->set_region_eden(hr);
3039 }
3040
3041 #ifdef ASSERT
3042
3043 class NoYoungRegionsClosure: public HeapRegionClosure {
3044 private:
3045 bool _success;
3046 public:
3047 NoYoungRegionsClosure() : _success(true) { }
3048 bool do_heap_region(HeapRegion* r) {
3049 if (r->is_young()) {
3050 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
3051 p2i(r->bottom()), p2i(r->end()));
3052 _success = false;
3053 }
3054 return false;
3055 }
3056 bool success() { return _success; }
3057 };
3058
3059 bool G1CollectedHeap::check_young_list_empty() {
3060 bool ret = (young_regions_count() == 0);
3061
3062 NoYoungRegionsClosure closure;
3063 heap_region_iterate(&closure);
3064 ret = ret && closure.success();
3065
3066 return ret;
3067 }
3068
3069 #endif // ASSERT
3070
3071 // Remove the given HeapRegion from the appropriate region set.
3072 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
3073 if (hr->is_archive()) {
3074 _archive_set.remove(hr);
3075 } else if (hr->is_humongous()) {
3076 _humongous_set.remove(hr);
3077 } else if (hr->is_old()) {
3078 _old_set.remove(hr);
3079 } else if (hr->is_young()) {
3080 // Note that emptying the eden and survivor lists is postponed and instead
3081 // done as the first step when rebuilding the regions sets again. The reason
3082 // for this is that during a full GC string deduplication needs to know if
3083 // a collected region was young or old when the full GC was initiated.
3084 hr->uninstall_surv_rate_group();
3085 } else {
3086 // We ignore free regions, we'll empty the free list afterwards.
3087 assert(hr->is_free(), "it cannot be another type");
3088 }
3089 }
3090
3091 void G1CollectedHeap::increase_used(size_t bytes) {
3092 _summary_bytes_used += bytes;
3093 }
3094
3095 void G1CollectedHeap::decrease_used(size_t bytes) {
3096 assert(_summary_bytes_used >= bytes,
3097 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
3098 _summary_bytes_used, bytes);
3099 _summary_bytes_used -= bytes;
3100 }
3101
3102 void G1CollectedHeap::set_used(size_t bytes) {
3103 _summary_bytes_used = bytes;
3104 }
3105
3106 class RebuildRegionSetsClosure : public HeapRegionClosure {
3107 private:
3108 bool _free_list_only;
3109
3110 HeapRegionSet* _old_set;
3111 HeapRegionSet* _archive_set;
3112 HeapRegionSet* _humongous_set;
3113
3114 HeapRegionManager* _hrm;
3115
3116 size_t _total_used;
3117
3118 public:
3119 RebuildRegionSetsClosure(bool free_list_only,
3120 HeapRegionSet* old_set,
3121 HeapRegionSet* archive_set,
3122 HeapRegionSet* humongous_set,
3123 HeapRegionManager* hrm) :
3124 _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set),
3125 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
3126 assert(_hrm->num_free_regions() == 0, "pre-condition");
3127 if (!free_list_only) {
3128 assert(_old_set->is_empty(), "pre-condition");
3129 assert(_archive_set->is_empty(), "pre-condition");
3130 assert(_humongous_set->is_empty(), "pre-condition");
3131 }
3132 }
3133
3134 bool do_heap_region(HeapRegion* r) {
3135 if (r->is_empty()) {
3136 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
3137 // Add free regions to the free list
3138 r->set_free();
3139 _hrm->insert_into_free_list(r);
3140 } else if (!_free_list_only) {
3141 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
3142
3143 if (r->is_humongous()) {
3144 _humongous_set->add(r);
3145 } else if (r->is_archive()) {
3146 _archive_set->add(r);
3147 } else {
3148 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
3149 // We now move all (non-humongous, non-old, non-archive) regions to old gen,
3150 // and register them as such.
3151 r->move_to_old();
3152 _old_set->add(r);
3153 }
3154 _total_used += r->used();
3155 }
3156
3157 return false;
3158 }
3159
3160 size_t total_used() {
3161 return _total_used;
3162 }
3163 };
3164
3165 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
3166 assert_at_safepoint_on_vm_thread();
3167
3168 if (!free_list_only) {
3169 _eden.clear();
3170 _survivor.clear();
3171 }
3172
3173 RebuildRegionSetsClosure cl(free_list_only,
3174 &_old_set, &_archive_set, &_humongous_set,
3175 &_hrm);
3176 heap_region_iterate(&cl);
3177
3178 if (!free_list_only) {
3179 set_used(cl.total_used());
3180 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
3181 }
3182 assert_used_and_recalculate_used_equal(this);
3183 }
3184
3185 // Methods for the mutator alloc region
3186
3187 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
3188 bool force,
3189 uint node_index) {
3190 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3191 bool should_allocate = policy()->should_allocate_mutator_region();
3192 if (force || should_allocate) {
3193 HeapRegion* new_alloc_region = new_region(word_size,
3194 HeapRegionType::Eden,
3195 false /* do_expand */,
3196 node_index);
3197 if (new_alloc_region != NULL) {
3198 set_region_short_lived_locked(new_alloc_region);
3199 _hr_printer.alloc(new_alloc_region, !should_allocate);
3200 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3201 return new_alloc_region;
3202 }
3203 }
3204 return NULL;
3205 }
3206
3207 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
3208 size_t allocated_bytes) {
3209 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3210 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
3211
3212 collection_set()->add_eden_region(alloc_region);
3213 increase_used(allocated_bytes);
3214 _eden.add_used_bytes(allocated_bytes);
3215 _hr_printer.retire(alloc_region);
3216
3217 // We update the eden sizes here, when the region is retired,
3218 // instead of when it's allocated, since this is the point that its
3219 // used space has been recorded in _summary_bytes_used.
3220 monitoring_support()->update_eden_size();
3221 }
3222
3223 // Methods for the GC alloc regions
3224
3225 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
3226 if (dest.is_old()) {
3227 return true;
3228 } else {
3229 return survivor_regions_count() < policy()->max_survivor_regions();
3230 }
3231 }
3232
3233 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
3234 assert(FreeList_lock->owned_by_self(), "pre-condition");
3235
3236 if (!has_more_regions(dest)) {
3237 return NULL;
3238 }
3239
3240 HeapRegionType type;
3241 if (dest.is_young()) {
3242 type = HeapRegionType::Survivor;
3243 } else {
3244 type = HeapRegionType::Old;
3245 }
3246
3247 HeapRegion* new_alloc_region = new_region(word_size,
3248 type,
3249 true /* do_expand */,
3250 node_index);
3251
3252 if (new_alloc_region != NULL) {
3253 if (type.is_survivor()) {
3254 new_alloc_region->set_survivor();
3255 _survivor.add(new_alloc_region);
3256 register_new_survivor_region_with_region_attr(new_alloc_region);
3257 } else {
3258 new_alloc_region->set_old();
3259 }
3260 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3261 register_region_with_region_attr(new_alloc_region);
3262 _hr_printer.alloc(new_alloc_region);
3263 return new_alloc_region;
3264 }
3265 return NULL;
3266 }
3267
3268 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
3269 size_t allocated_bytes,
3270 G1HeapRegionAttr dest) {
3271 _bytes_used_during_gc += allocated_bytes;
3272 if (dest.is_old()) {
3273 old_set_add(alloc_region);
3274 } else {
3275 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
3276 _survivor.add_used_bytes(allocated_bytes);
3277 }
3278
3279 bool const during_im = collector_state()->in_concurrent_start_gc();
3280 if (during_im && allocated_bytes > 0) {
3281 _cm->root_regions()->add(alloc_region->top_at_mark_start(), alloc_region->top());
3282 }
3283 _hr_printer.retire(alloc_region);
3284 }
3285
3286 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
3287 bool expanded = false;
3288 uint index = _hrm.find_highest_free(&expanded);
3289
3290 if (index != G1_NO_HRM_INDEX) {
3291 if (expanded) {
3292 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
3293 HeapRegion::GrainWords * HeapWordSize);
3294 }
3295 return _hrm.allocate_free_regions_starting_at(index, 1);
3296 }
3297 return NULL;
3298 }
3299
3300 void G1CollectedHeap::mark_evac_failure_object(const oop obj) const {
3301 // All objects failing evacuation are live. What we'll do is
3302 // that we'll update the marking info so that they are
3303 // all below TAMS and explicitly marked.
3304 _cm->raw_mark_in_bitmap(obj);
3305 }
3306
3307 // Optimized nmethod scanning
3308 class RegisterNMethodOopClosure: public OopClosure {
3309 G1CollectedHeap* _g1h;
3310 nmethod* _nm;
3311
3312 public:
3313 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3314 _g1h(g1h), _nm(nm) {}
3315
3316 void do_oop(oop* p) {
3317 oop heap_oop = RawAccess<>::oop_load(p);
3318 if (!CompressedOops::is_null(heap_oop)) {
3319 oop obj = CompressedOops::decode_not_null(heap_oop);
3320 HeapRegion* hr = _g1h->heap_region_containing(obj);
3321 assert(!hr->is_continues_humongous(),
3322 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3323 " starting at " HR_FORMAT,
3324 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3325
3326 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3327 hr->add_code_root_locked(_nm);
3328 }
3329 }
3330
3331 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3332 };
3333
3334 class UnregisterNMethodOopClosure: public OopClosure {
3335 G1CollectedHeap* _g1h;
3336 nmethod* _nm;
3337
3338 public:
3339 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3340 _g1h(g1h), _nm(nm) {}
3341
3342 void do_oop(oop* p) {
3343 oop heap_oop = RawAccess<>::oop_load(p);
3344 if (!CompressedOops::is_null(heap_oop)) {
3345 oop obj = CompressedOops::decode_not_null(heap_oop);
3346 HeapRegion* hr = _g1h->heap_region_containing(obj);
3347 assert(!hr->is_continues_humongous(),
3348 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3349 " starting at " HR_FORMAT,
3350 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3351
3352 hr->remove_code_root(_nm);
3353 }
3354 }
3355
3356 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3357 };
3358
3359 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3360 guarantee(nm != NULL, "sanity");
3361 RegisterNMethodOopClosure reg_cl(this, nm);
3362 nm->oops_do(®_cl);
3363 }
3364
3365 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3366 guarantee(nm != NULL, "sanity");
3367 UnregisterNMethodOopClosure reg_cl(this, nm);
3368 nm->oops_do(®_cl, true);
3369 }
3370
3371 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3372 if (evacuation_failed) {
3373 // Reset the G1EvacuationFailureALot counters and flags
3374 evac_failure_injector()->reset();
3375
3376 set_used(recalculate_used());
3377
3378 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
3379 } else {
3380 // The "used" of the collection set have already been subtracted
3381 // when they were freed. Add in the bytes used.
3382 increase_used(_bytes_used_during_gc);
3383 }
3384 }
3385
3386 void G1CollectedHeap::reset_hot_card_cache() {
3387 _hot_card_cache->reset_hot_cache();
3388 _hot_card_cache->set_use_cache(true);
3389 }
3390
3391 void G1CollectedHeap::purge_code_root_memory() {
3392 G1CodeRootSet::purge();
3393 }
3394
3395 class RebuildCodeRootClosure: public CodeBlobClosure {
3396 G1CollectedHeap* _g1h;
3397
3398 public:
3399 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3400 _g1h(g1h) {}
3401
3402 void do_code_blob(CodeBlob* cb) {
3403 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
3404 if (nm == NULL) {
3405 return;
3406 }
3407
3408 _g1h->register_nmethod(nm);
3409 }
3410 };
3411
3412 void G1CollectedHeap::rebuild_code_roots() {
3413 RebuildCodeRootClosure blob_cl(this);
3414 CodeCache::blobs_do(&blob_cl);
3415 }
3416
3417 void G1CollectedHeap::initialize_serviceability() {
3418 _monitoring_support->initialize_serviceability();
3419 }
3420
3421 MemoryUsage G1CollectedHeap::memory_usage() {
3422 return _monitoring_support->memory_usage();
3423 }
3424
3425 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3426 return _monitoring_support->memory_managers();
3427 }
3428
3429 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3430 return _monitoring_support->memory_pools();
3431 }
3432
3433 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3434 HeapRegion* region = heap_region_containing(start);
3435 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3436 }
3437
3438 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive() {
3439 if (!Continuations::is_gc_marking_cycle_active()) {
3440 // This is the normal case when we do not call collect when a
3441 // concurrent mark is ongoing. We then start a new code marking
3442 // cycle. If, on the other hand, a concurrent mark is ongoing, we
3443 // will be conservative and use the last code marking cycle. Code
3444 // caches marked between the two concurrent marks will live a bit
3445 // longer than needed.
3446 Continuations::on_gc_marking_cycle_start();
3447 Continuations::arm_all_nmethods();
3448 }
3449 }