1 /*
2 * Copyright (c) 2001, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "compiler/oopMap.hpp"
32 #include "gc/g1/g1Allocator.inline.hpp"
33 #include "gc/g1/g1Arguments.hpp"
34 #include "gc/g1/g1BarrierSet.hpp"
35 #include "gc/g1/g1BatchedTask.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectionSetCandidates.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1ConcurrentRefine.hpp"
41 #include "gc/g1/g1ConcurrentRefineThread.hpp"
42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
43 #include "gc/g1/g1DirtyCardQueue.hpp"
44 #include "gc/g1/g1EvacStats.inline.hpp"
45 #include "gc/g1/g1FullCollector.hpp"
46 #include "gc/g1/g1GCCounters.hpp"
47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
48 #include "gc/g1/g1GCPhaseTimes.hpp"
49 #include "gc/g1/g1GCPauseType.hpp"
50 #include "gc/g1/g1HeapSizingPolicy.hpp"
51 #include "gc/g1/g1HeapTransition.hpp"
52 #include "gc/g1/g1HeapVerifier.hpp"
53 #include "gc/g1/g1InitLogger.hpp"
54 #include "gc/g1/g1MemoryPool.hpp"
55 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.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/g1ServiceThread.hpp"
68 #include "gc/g1/g1ThreadLocalData.hpp"
69 #include "gc/g1/g1Trace.hpp"
70 #include "gc/g1/g1UncommitRegionTask.hpp"
71 #include "gc/g1/g1VMOperations.hpp"
72 #include "gc/g1/g1YoungCollector.hpp"
73 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp"
74 #include "gc/g1/heapRegion.inline.hpp"
75 #include "gc/g1/heapRegionRemSet.inline.hpp"
76 #include "gc/g1/heapRegionSet.inline.hpp"
77 #include "gc/shared/concurrentGCBreakpoints.hpp"
78 #include "gc/shared/gcBehaviours.hpp"
79 #include "gc/shared/gcHeapSummary.hpp"
80 #include "gc/shared/gcId.hpp"
81 #include "gc/shared/gcLocker.inline.hpp"
82 #include "gc/shared/gcTimer.hpp"
83 #include "gc/shared/gcTraceTime.inline.hpp"
84 #include "gc/shared/generationSpec.hpp"
85 #include "gc/shared/isGCActiveMark.hpp"
86 #include "gc/shared/locationPrinter.inline.hpp"
87 #include "gc/shared/oopStorageParState.hpp"
88 #include "gc/shared/preservedMarks.inline.hpp"
89 #include "gc/shared/referenceProcessor.inline.hpp"
90 #include "gc/shared/slidingForwarding.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 uint G1CollectedHeap::get_chunks_per_region() {
148 uint log_region_size = HeapRegion::LogOfHRGrainBytes;
149 // Limit the expected input values to current known possible values of the
150 // (log) region size. Adjust as necessary after testing if changing the permissible
151 // values for region size.
152 assert(log_region_size >= 20 && log_region_size <= 29,
153 "expected value in [20,29], but got %u", log_region_size);
154 return 1u << (log_region_size / 2 - 4);
155 }
156
157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
158 MemRegion mr) {
159 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
160 }
161
162 // Private methods.
163
164 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
165 HeapRegionType type,
166 bool do_expand,
167 uint node_index) {
168 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
169 "the only time we use this to allocate a humongous region is "
170 "when we are allocating a single humongous region");
171
172 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
173
174 if (res == nullptr && do_expand) {
175 // Currently, only attempts to allocate GC alloc regions set
176 // do_expand to true. So, we should only reach here during a
177 // safepoint.
178 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
179
180 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
181 word_size * HeapWordSize);
182
183 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
184 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
185 word_size * HeapWordSize);
186 if (expand_single_region(node_index)) {
187 // Given that expand_single_region() succeeded in expanding the heap, and we
188 // always expand the heap by an amount aligned to the heap
189 // region size, the free list should in theory not be empty.
190 // In either case allocate_free_region() will check for null.
191 res = _hrm.allocate_free_region(type, node_index);
192 }
193 }
194 return res;
195 }
196
197 void G1CollectedHeap::set_humongous_metadata(HeapRegion* first_hr,
198 uint num_regions,
199 size_t word_size,
200 bool update_remsets) {
201 // Calculate the new top of the humongous object.
202 HeapWord* obj_top = first_hr->bottom() + word_size;
203 // The word size sum of all the regions used
204 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
205 assert(word_size <= word_size_sum, "sanity");
206
207 // How many words memory we "waste" which cannot hold a filler object.
208 size_t words_not_fillable = 0;
209
210 // Pad out the unused tail of the last region with filler
211 // objects, for improved usage accounting.
212
213 // How many words can we use for filler objects.
214 size_t words_fillable = word_size_sum - word_size;
215
216 if (words_fillable >= G1CollectedHeap::min_fill_size()) {
217 G1CollectedHeap::fill_with_objects(obj_top, words_fillable);
218 } else {
219 // We have space to fill, but we cannot fit an object there.
220 words_not_fillable = words_fillable;
221 words_fillable = 0;
222 }
223
224 // We will set up the first region as "starts humongous". This
225 // will also update the BOT covering all the regions to reflect
226 // that there is a single object that starts at the bottom of the
227 // first region.
228 first_hr->hr_clear(false /* clear_space */);
229 first_hr->set_starts_humongous(obj_top, words_fillable);
230
231 if (update_remsets) {
232 _policy->remset_tracker()->update_at_allocate(first_hr);
233 }
234
235 // Indices of first and last regions in the series.
236 uint first = first_hr->hrm_index();
237 uint last = first + num_regions - 1;
238
239 HeapRegion* hr = nullptr;
240 for (uint i = first + 1; i <= last; ++i) {
241 hr = region_at(i);
242 hr->hr_clear(false /* clear_space */);
243 hr->set_continues_humongous(first_hr);
244 if (update_remsets) {
245 _policy->remset_tracker()->update_at_allocate(hr);
246 }
247 }
248
249 // Up to this point no concurrent thread would have been able to
250 // do any scanning on any region in this series. All the top
251 // fields still point to bottom, so the intersection between
252 // [bottom,top] and [card_start,card_end] will be empty. Before we
253 // update the top fields, we'll do a storestore to make sure that
254 // no thread sees the update to top before the zeroing of the
255 // object header and the BOT initialization.
256 OrderAccess::storestore();
257
258 // Now, we will update the top fields of the "continues humongous"
259 // regions except the last one.
260 for (uint i = first; i < last; ++i) {
261 hr = region_at(i);
262 hr->set_top(hr->end());
263 }
264
265 hr = region_at(last);
266 // If we cannot fit a filler object, we must set top to the end
267 // of the humongous object, otherwise we cannot iterate the heap
268 // and the BOT will not be complete.
269 hr->set_top(hr->end() - words_not_fillable);
270
271 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
272 "obj_top should be in last region");
273
274 assert(words_not_fillable == 0 ||
275 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
276 "Miscalculation in humongous allocation");
277 }
278
279 HeapWord*
280 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
281 uint num_regions,
282 size_t word_size) {
283 assert(first_hr != nullptr, "pre-condition");
284 assert(is_humongous(word_size), "word_size should be humongous");
285 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
286
287 // Index of last region in the series.
288 uint first = first_hr->hrm_index();
289 uint last = first + num_regions - 1;
290
291 // We need to initialize the region(s) we just discovered. This is
292 // a bit tricky given that it can happen concurrently with
293 // refinement threads refining cards on these regions and
294 // potentially wanting to refine the BOT as they are scanning
295 // those cards (this can happen shortly after a cleanup; see CR
296 // 6991377). So we have to set up the region(s) carefully and in
297 // a specific order.
298
299 // The passed in hr will be the "starts humongous" region. The header
300 // of the new object will be placed at the bottom of this region.
301 HeapWord* new_obj = first_hr->bottom();
302
303 // First, we need to zero the header of the space that we will be
304 // allocating. When we update top further down, some refinement
305 // threads might try to scan the region. By zeroing the header we
306 // ensure that any thread that will try to scan the region will
307 // come across the zero klass word and bail out.
308 //
309 // NOTE: It would not have been correct to have used
310 // CollectedHeap::fill_with_object() and make the space look like
311 // an int array. The thread that is doing the allocation will
312 // later update the object header to a potentially different array
313 // type and, for a very short period of time, the klass and length
314 // fields will be inconsistent. This could cause a refinement
315 // thread to calculate the object size incorrectly.
316 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
317
318 // Next, update the metadata for the regions.
319 set_humongous_metadata(first_hr, num_regions, word_size, true);
320
321 HeapRegion* last_hr = region_at(last);
322 size_t used = byte_size(first_hr->bottom(), last_hr->top());
323
324 increase_used(used);
325
326 for (uint i = first; i <= last; ++i) {
327 HeapRegion *hr = region_at(i);
328 _humongous_set.add(hr);
329 _hr_printer.alloc(hr);
330 }
331
332 return new_obj;
333 }
334
335 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
336 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
337 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
338 }
339
340 // If could fit into free regions w/o expansion, try.
341 // Otherwise, if can expand, do so.
342 // Otherwise, if using ex regions might help, try with ex given back.
343 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
344 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
345
346 _verifier->verify_region_sets_optional();
347
348 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
349
350 // Policy: First try to allocate a humongous object in the free list.
351 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
352 if (humongous_start == nullptr) {
353 // Policy: We could not find enough regions for the humongous object in the
354 // free list. Look through the heap to find a mix of free and uncommitted regions.
355 // If so, expand the heap and allocate the humongous object.
356 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
357 if (humongous_start != nullptr) {
358 // We managed to find a region by expanding the heap.
359 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
360 word_size * HeapWordSize);
361 policy()->record_new_heap_size(num_regions());
362 } else {
363 // Policy: Potentially trigger a defragmentation GC.
364 }
365 }
366
367 HeapWord* result = nullptr;
368 if (humongous_start != nullptr) {
369 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
370 assert(result != nullptr, "it should always return a valid result");
371
372 // A successful humongous object allocation changes the used space
373 // information of the old generation so we need to recalculate the
374 // sizes and update the jstat counters here.
375 monitoring_support()->update_sizes();
376 }
377
378 _verifier->verify_region_sets_optional();
379
380 return result;
381 }
382
383 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
384 size_t requested_size,
385 size_t* actual_size) {
386 assert_heap_not_locked_and_not_at_safepoint();
387 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
388
389 return attempt_allocation(min_size, requested_size, actual_size);
390 }
391
392 HeapWord*
393 G1CollectedHeap::mem_allocate(size_t word_size,
394 bool* gc_overhead_limit_was_exceeded) {
395 assert_heap_not_locked_and_not_at_safepoint();
396
397 if (is_humongous(word_size)) {
398 return attempt_allocation_humongous(word_size);
399 }
400 size_t dummy = 0;
401 return attempt_allocation(word_size, word_size, &dummy);
402 }
403
404 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
405 ResourceMark rm; // For retrieving the thread names in log messages.
406
407 // Make sure you read the note in attempt_allocation_humongous().
408
409 assert_heap_not_locked_and_not_at_safepoint();
410 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
411 "be called for humongous allocation requests");
412
413 // We should only get here after the first-level allocation attempt
414 // (attempt_allocation()) failed to allocate.
415
416 // We will loop until a) we manage to successfully perform the
417 // allocation or b) we successfully schedule a collection which
418 // fails to perform the allocation. b) is the only case when we'll
419 // return null.
420 HeapWord* result = nullptr;
421 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
422 bool should_try_gc;
423 uint gc_count_before;
424
425 {
426 MutexLocker x(Heap_lock);
427
428 // Now that we have the lock, we first retry the allocation in case another
429 // thread changed the region while we were waiting to acquire the lock.
430 result = _allocator->attempt_allocation_locked(word_size);
431 if (result != nullptr) {
432 return result;
433 }
434
435 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
436 // This is different to when only GCLocker::needs_gc() is set: try to avoid
437 // waiting because the GCLocker is active to not wait too long.
438 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
439 // No need for an ergo message here, can_expand_young_list() does this when
440 // it returns true.
441 result = _allocator->attempt_allocation_force(word_size);
442 if (result != nullptr) {
443 return result;
444 }
445 }
446
447 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
448 // the GCLocker initiated GC has been performed and then retry. This includes
449 // the case when the GC Locker is not active but has not been performed.
450 should_try_gc = !GCLocker::needs_gc();
451 // Read the GC count while still holding the Heap_lock.
452 gc_count_before = total_collections();
453 }
454
455 if (should_try_gc) {
456 bool succeeded;
457 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
458 if (result != nullptr) {
459 assert(succeeded, "only way to get back a non-null result");
460 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
461 Thread::current()->name(), p2i(result));
462 return result;
463 }
464
465 if (succeeded) {
466 // We successfully scheduled a collection which failed to allocate. No
467 // point in trying to allocate further. We'll just return null.
468 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
469 SIZE_FORMAT " words", Thread::current()->name(), word_size);
470 return nullptr;
471 }
472 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
473 Thread::current()->name(), word_size);
474 } else {
475 // Failed to schedule a collection.
476 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
477 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
478 SIZE_FORMAT " words", Thread::current()->name(), word_size);
479 return nullptr;
480 }
481 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
482 // The GCLocker is either active or the GCLocker initiated
483 // GC has not yet been performed. Stall until it is and
484 // then retry the allocation.
485 GCLocker::stall_until_clear();
486 gclocker_retry_count += 1;
487 }
488
489 // We can reach here if we were unsuccessful in scheduling a
490 // collection (because another thread beat us to it) or if we were
491 // stalled due to the GC locker. In either can we should retry the
492 // allocation attempt in case another thread successfully
493 // performed a collection and reclaimed enough space. We do the
494 // first attempt (without holding the Heap_lock) here and the
495 // follow-on attempt will be at the start of the next loop
496 // iteration (after taking the Heap_lock).
497 size_t dummy = 0;
498 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
499 if (result != nullptr) {
500 return result;
501 }
502
503 // Give a warning if we seem to be looping forever.
504 if ((QueuedAllocationWarningCount > 0) &&
505 (try_count % QueuedAllocationWarningCount == 0)) {
506 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
507 Thread::current()->name(), try_count, word_size);
508 }
509 }
510
511 ShouldNotReachHere();
512 return nullptr;
513 }
514
515 bool G1CollectedHeap::check_archive_addresses(MemRegion range) {
516 return _hrm.reserved().contains(range);
517 }
518
519 template <typename Func>
520 void G1CollectedHeap::iterate_regions_in_range(MemRegion range, const Func& func) {
521 // Mark each G1 region touched by the range as old, add it to
522 // the old set, and set top.
523 HeapRegion* curr_region = _hrm.addr_to_region(range.start());
524 HeapRegion* end_region = _hrm.addr_to_region(range.last());
525
526 while (curr_region != nullptr) {
527 bool is_last = curr_region == end_region;
528 HeapRegion* next_region = is_last ? nullptr : _hrm.next_region_in_heap(curr_region);
529
530 func(curr_region, is_last);
531
532 curr_region = next_region;
533 }
534 }
535
536 bool G1CollectedHeap::alloc_archive_regions(MemRegion range) {
537 assert(!is_init_completed(), "Expect to be called at JVM init time");
538 MutexLocker x(Heap_lock);
539
540 MemRegion reserved = _hrm.reserved();
541
542 // Temporarily disable pretouching of heap pages. This interface is used
543 // when mmap'ing archived heap data in, so pre-touching is wasted.
544 FlagSetting fs(AlwaysPreTouch, false);
545
546 // For the specified MemRegion range, allocate the corresponding G1
547 // region(s) and mark them as old region(s).
548 HeapWord* start_address = range.start();
549 size_t word_size = range.word_size();
550 HeapWord* last_address = range.last();
551 size_t commits = 0;
552
553 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
554 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
555 p2i(start_address), p2i(last_address));
556
557 // Perform the actual region allocation, exiting if it fails.
558 // Then note how much new space we have allocated.
559 if (!_hrm.allocate_containing_regions(range, &commits, workers())) {
560 return false;
561 }
562 increase_used(word_size * HeapWordSize);
563 if (commits != 0) {
564 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
565 HeapRegion::GrainWords * HeapWordSize * commits);
566
567 }
568
569 // Mark each G1 region touched by the range as old, add it to
570 // the old set, and set top.
571 auto set_region_to_old = [&] (HeapRegion* r, bool is_last) {
572 assert(r->is_empty(), "Region already in use (%u)", r->hrm_index());
573
574 HeapWord* top = is_last ? last_address + 1 : r->end();
575 r->set_top(top);
576
577 r->set_old();
578 _hr_printer.alloc(r);
579 _old_set.add(r);
580 };
581
582 iterate_regions_in_range(range, set_region_to_old);
583 return true;
584 }
585
586 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion range) {
587 assert(!is_init_completed(), "Expect to be called at JVM init time");
588
589 iterate_regions_in_range(range,
590 [&] (HeapRegion* r, bool is_last) {
591 r->update_bot();
592 });
593 }
594
595 void G1CollectedHeap::dealloc_archive_regions(MemRegion range) {
596 assert(!is_init_completed(), "Expect to be called at JVM init time");
597 MemRegion reserved = _hrm.reserved();
598 size_t size_used = 0;
599 uint shrink_count = 0;
600
601 // Free the G1 regions that are within the specified range.
602 MutexLocker x(Heap_lock);
603 HeapWord* start_address = range.start();
604 HeapWord* last_address = range.last();
605
606 assert(reserved.contains(start_address) && reserved.contains(last_address),
607 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
608 p2i(start_address), p2i(last_address));
609 size_used += range.byte_size();
610
611 // Free, empty and uncommit regions with CDS archive content.
612 auto dealloc_archive_region = [&] (HeapRegion* r, bool is_last) {
613 guarantee(r->is_old(), "Expected old region at index %u", r->hrm_index());
614 _old_set.remove(r);
615 r->set_free();
616 r->set_top(r->bottom());
617 _hrm.shrink_at(r->hrm_index(), 1);
618 shrink_count++;
619 };
620
621 iterate_regions_in_range(range, dealloc_archive_region);
622
623 if (shrink_count != 0) {
624 log_debug(gc, ergo, heap)("Attempt heap shrinking (CDS archive regions). Total size: " SIZE_FORMAT "B",
625 HeapRegion::GrainWords * HeapWordSize * shrink_count);
626 // Explicit uncommit.
627 uncommit_regions(shrink_count);
628 }
629 decrease_used(size_used);
630 }
631
632 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
633 size_t desired_word_size,
634 size_t* actual_word_size) {
635 assert_heap_not_locked_and_not_at_safepoint();
636 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
637 "be called for humongous allocation requests");
638
639 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
640
641 if (result == nullptr) {
642 *actual_word_size = desired_word_size;
643 result = attempt_allocation_slow(desired_word_size);
644 }
645
646 assert_heap_not_locked();
647 if (result != nullptr) {
648 assert(*actual_word_size != 0, "Actual size must have been set here");
649 dirty_young_block(result, *actual_word_size);
650 } else {
651 *actual_word_size = 0;
652 }
653
654 return result;
655 }
656
657 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
658 ResourceMark rm; // For retrieving the thread names in log messages.
659
660 // The structure of this method has a lot of similarities to
661 // attempt_allocation_slow(). The reason these two were not merged
662 // into a single one is that such a method would require several "if
663 // allocation is not humongous do this, otherwise do that"
664 // conditional paths which would obscure its flow. In fact, an early
665 // version of this code did use a unified method which was harder to
666 // follow and, as a result, it had subtle bugs that were hard to
667 // track down. So keeping these two methods separate allows each to
668 // be more readable. It will be good to keep these two in sync as
669 // much as possible.
670
671 assert_heap_not_locked_and_not_at_safepoint();
672 assert(is_humongous(word_size), "attempt_allocation_humongous() "
673 "should only be called for humongous allocations");
674
675 // Humongous objects can exhaust the heap quickly, so we should check if we
676 // need to start a marking cycle at each humongous object allocation. We do
677 // the check before we do the actual allocation. The reason for doing it
678 // before the allocation is that we avoid having to keep track of the newly
679 // allocated memory while we do a GC.
680 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
681 word_size)) {
682 collect(GCCause::_g1_humongous_allocation);
683 }
684
685 // We will loop until a) we manage to successfully perform the
686 // allocation or b) we successfully schedule a collection which
687 // fails to perform the allocation. b) is the only case when we'll
688 // return null.
689 HeapWord* result = nullptr;
690 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
691 bool should_try_gc;
692 uint gc_count_before;
693
694
695 {
696 MutexLocker x(Heap_lock);
697
698 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
699 // Given that humongous objects are not allocated in young
700 // regions, we'll first try to do the allocation without doing a
701 // collection hoping that there's enough space in the heap.
702 result = humongous_obj_allocate(word_size);
703 if (result != nullptr) {
704 policy()->old_gen_alloc_tracker()->
705 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
706 return result;
707 }
708
709 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
710 // the GCLocker initiated GC has been performed and then retry. This includes
711 // the case when the GC Locker is not active but has not been performed.
712 should_try_gc = !GCLocker::needs_gc();
713 // Read the GC count while still holding the Heap_lock.
714 gc_count_before = total_collections();
715 }
716
717 if (should_try_gc) {
718 bool succeeded;
719 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
720 if (result != nullptr) {
721 assert(succeeded, "only way to get back a non-null result");
722 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
723 Thread::current()->name(), p2i(result));
724 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
725 policy()->old_gen_alloc_tracker()->
726 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
727 return result;
728 }
729
730 if (succeeded) {
731 // We successfully scheduled a collection which failed to allocate. No
732 // point in trying to allocate further. We'll just return null.
733 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
734 SIZE_FORMAT " words", Thread::current()->name(), word_size);
735 return nullptr;
736 }
737 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
738 Thread::current()->name(), word_size);
739 } else {
740 // Failed to schedule a collection.
741 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
742 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
743 SIZE_FORMAT " words", Thread::current()->name(), word_size);
744 return nullptr;
745 }
746 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
747 // The GCLocker is either active or the GCLocker initiated
748 // GC has not yet been performed. Stall until it is and
749 // then retry the allocation.
750 GCLocker::stall_until_clear();
751 gclocker_retry_count += 1;
752 }
753
754
755 // We can reach here if we were unsuccessful in scheduling a
756 // collection (because another thread beat us to it) or if we were
757 // stalled due to the GC locker. In either can we should retry the
758 // allocation attempt in case another thread successfully
759 // performed a collection and reclaimed enough space.
760 // Humongous object allocation always needs a lock, so we wait for the retry
761 // in the next iteration of the loop, unlike for the regular iteration case.
762 // Give a warning if we seem to be looping forever.
763
764 if ((QueuedAllocationWarningCount > 0) &&
765 (try_count % QueuedAllocationWarningCount == 0)) {
766 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
767 Thread::current()->name(), try_count, word_size);
768 }
769 }
770
771 ShouldNotReachHere();
772 return nullptr;
773 }
774
775 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
776 bool expect_null_mutator_alloc_region) {
777 assert_at_safepoint_on_vm_thread();
778 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
779 "the current alloc region was unexpectedly found to be non-null");
780
781 if (!is_humongous(word_size)) {
782 return _allocator->attempt_allocation_locked(word_size);
783 } else {
784 HeapWord* result = humongous_obj_allocate(word_size);
785 if (result != nullptr && policy()->need_to_start_conc_mark("STW humongous allocation")) {
786 collector_state()->set_initiate_conc_mark_if_possible(true);
787 }
788 return result;
789 }
790
791 ShouldNotReachHere();
792 }
793
794 class PostCompactionPrinterClosure: public HeapRegionClosure {
795 private:
796 G1HRPrinter* _hr_printer;
797 public:
798 bool do_heap_region(HeapRegion* hr) {
799 assert(!hr->is_young(), "not expecting to find young regions");
800 _hr_printer->post_compaction(hr);
801 return false;
802 }
803
804 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
805 : _hr_printer(hr_printer) { }
806 };
807
808 void G1CollectedHeap::print_heap_after_full_collection() {
809 // Post collection region logging.
810 // We should do this after we potentially resize the heap so
811 // that all the COMMIT / UNCOMMIT events are generated before
812 // the compaction events.
813 if (_hr_printer.is_active()) {
814 PostCompactionPrinterClosure cl(hr_printer());
815 heap_region_iterate(&cl);
816 }
817 }
818
819 bool G1CollectedHeap::abort_concurrent_cycle() {
820 // Disable discovery and empty the discovered lists
821 // for the CM ref processor.
822 _ref_processor_cm->disable_discovery();
823 _ref_processor_cm->abandon_partial_discovery();
824 _ref_processor_cm->verify_no_references_recorded();
825
826 // Abandon current iterations of concurrent marking and concurrent
827 // refinement, if any are in progress.
828 return concurrent_mark()->concurrent_cycle_abort();
829 }
830
831 void G1CollectedHeap::prepare_heap_for_full_collection() {
832 // Make sure we'll choose a new allocation region afterwards.
833 _allocator->release_mutator_alloc_regions();
834 _allocator->abandon_gc_alloc_regions();
835
836 // We may have added regions to the current incremental collection
837 // set between the last GC or pause and now. We need to clear the
838 // incremental collection set and then start rebuilding it afresh
839 // after this full GC.
840 abandon_collection_set(collection_set());
841
842 _hrm.remove_all_free_regions();
843 }
844
845 void G1CollectedHeap::verify_before_full_collection() {
846 assert_used_and_recalculate_used_equal(this);
847 if (!VerifyBeforeGC) {
848 return;
849 }
850 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
851 return;
852 }
853 _verifier->verify_region_sets_optional();
854 _verifier->verify_before_gc();
855 _verifier->verify_bitmap_clear(true /* above_tams_only */);
856 }
857
858 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
859 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
860 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
861 DEBUG_ONLY(MetaspaceUtils::verify();)
862
863 // Prepare heap for normal collections.
864 assert(num_free_regions() == 0, "we should not have added any free regions");
865 rebuild_region_sets(false /* free_list_only */);
866 abort_refinement();
867 resize_heap_if_necessary();
868 uncommit_regions_if_necessary();
869
870 // Rebuild the code root lists for each region
871 rebuild_code_roots();
872
873 start_new_collection_set();
874 _allocator->init_mutator_alloc_regions();
875
876 // Post collection state updates.
877 MetaspaceGC::compute_new_size();
878 }
879
880 void G1CollectedHeap::abort_refinement() {
881 // Discard all remembered set updates and reset refinement statistics.
882 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
883 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
884 "DCQS should be empty");
885 concurrent_refine()->get_and_reset_refinement_stats();
886 }
887
888 void G1CollectedHeap::verify_after_full_collection() {
889 if (!VerifyAfterGC) {
890 return;
891 }
892 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
893 return;
894 }
895 _hrm.verify_optional();
896 _verifier->verify_region_sets_optional();
897 _verifier->verify_after_gc();
898 _verifier->verify_bitmap_clear(false /* above_tams_only */);
899
900 // At this point there should be no regions in the
901 // entire heap tagged as young.
902 assert(check_young_list_empty(), "young list should be empty at this point");
903
904 // Note: since we've just done a full GC, concurrent
905 // marking is no longer active. Therefore we need not
906 // re-enable reference discovery for the CM ref processor.
907 // That will be done at the start of the next marking cycle.
908 // We also know that the STW processor should no longer
909 // discover any new references.
910 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
911 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
912 _ref_processor_stw->verify_no_references_recorded();
913 _ref_processor_cm->verify_no_references_recorded();
914 }
915
916 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs,
917 bool do_maximal_compaction) {
918 assert_at_safepoint_on_vm_thread();
919
920 if (GCLocker::check_active_before_gc()) {
921 // Full GC was not completed.
922 return false;
923 }
924
925 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
926 soft_ref_policy()->should_clear_all_soft_refs();
927
928 G1FullGCMark gc_mark;
929 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true);
930 G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
931
932 collector.prepare_collection();
933 collector.collect();
934 collector.complete_collection();
935
936 // Full collection was successfully completed.
937 return true;
938 }
939
940 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
941 // Currently, there is no facility in the do_full_collection(bool) API to notify
942 // the caller that the collection did not succeed (e.g., because it was locked
943 // out by the GC locker). So, right now, we'll ignore the return value.
944
945 do_full_collection(clear_all_soft_refs,
946 false /* do_maximal_compaction */);
947 }
948
949 bool G1CollectedHeap::upgrade_to_full_collection() {
950 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
951 log_info(gc, ergo)("Attempting full compaction clearing soft references");
952 bool success = do_full_collection(true /* clear_all_soft_refs */,
953 false /* do_maximal_compaction */);
954 // do_full_collection only fails if blocked by GC locker and that can't
955 // be the case here since we only call this when already completed one gc.
956 assert(success, "invariant");
957 return success;
958 }
959
960 void G1CollectedHeap::resize_heap_if_necessary() {
961 assert_at_safepoint_on_vm_thread();
962
963 bool should_expand;
964 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
965
966 if (resize_amount == 0) {
967 return;
968 } else if (should_expand) {
969 expand(resize_amount, _workers);
970 } else {
971 shrink(resize_amount);
972 }
973 }
974
975 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
976 bool do_gc,
977 bool maximal_compaction,
978 bool expect_null_mutator_alloc_region,
979 bool* gc_succeeded) {
980 *gc_succeeded = true;
981 // Let's attempt the allocation first.
982 HeapWord* result =
983 attempt_allocation_at_safepoint(word_size,
984 expect_null_mutator_alloc_region);
985 if (result != nullptr) {
986 return result;
987 }
988
989 // In a G1 heap, we're supposed to keep allocation from failing by
990 // incremental pauses. Therefore, at least for now, we'll favor
991 // expansion over collection. (This might change in the future if we can
992 // do something smarter than full collection to satisfy a failed alloc.)
993 result = expand_and_allocate(word_size);
994 if (result != nullptr) {
995 return result;
996 }
997
998 if (do_gc) {
999 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1000 // Expansion didn't work, we'll try to do a Full GC.
1001 // If maximal_compaction is set we clear all soft references and don't
1002 // allow any dead wood to be left on the heap.
1003 if (maximal_compaction) {
1004 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
1005 } else {
1006 log_info(gc, ergo)("Attempting full compaction");
1007 }
1008 *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ ,
1009 maximal_compaction /* do_maximal_compaction */);
1010 }
1011
1012 return nullptr;
1013 }
1014
1015 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1016 bool* succeeded) {
1017 assert_at_safepoint_on_vm_thread();
1018
1019 // Attempts to allocate followed by Full GC.
1020 HeapWord* result =
1021 satisfy_failed_allocation_helper(word_size,
1022 true, /* do_gc */
1023 false, /* maximum_collection */
1024 false, /* expect_null_mutator_alloc_region */
1025 succeeded);
1026
1027 if (result != nullptr || !*succeeded) {
1028 return result;
1029 }
1030
1031 // Attempts to allocate followed by Full GC that will collect all soft references.
1032 result = satisfy_failed_allocation_helper(word_size,
1033 true, /* do_gc */
1034 true, /* maximum_collection */
1035 true, /* expect_null_mutator_alloc_region */
1036 succeeded);
1037
1038 if (result != nullptr || !*succeeded) {
1039 return result;
1040 }
1041
1042 // Attempts to allocate, no GC
1043 result = satisfy_failed_allocation_helper(word_size,
1044 false, /* do_gc */
1045 false, /* maximum_collection */
1046 true, /* expect_null_mutator_alloc_region */
1047 succeeded);
1048
1049 if (result != nullptr) {
1050 return result;
1051 }
1052
1053 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1054 "Flag should have been handled and cleared prior to this point");
1055
1056 // What else? We might try synchronous finalization later. If the total
1057 // space available is large enough for the allocation, then a more
1058 // complete compaction phase than we've tried so far might be
1059 // appropriate.
1060 return nullptr;
1061 }
1062
1063 // Attempting to expand the heap sufficiently
1064 // to support an allocation of the given "word_size". If
1065 // successful, perform the allocation and return the address of the
1066 // allocated block, or else null.
1067
1068 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1069 assert_at_safepoint_on_vm_thread();
1070
1071 _verifier->verify_region_sets_optional();
1072
1073 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1074 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1075 word_size * HeapWordSize);
1076
1077
1078 if (expand(expand_bytes, _workers)) {
1079 _hrm.verify_optional();
1080 _verifier->verify_region_sets_optional();
1081 return attempt_allocation_at_safepoint(word_size,
1082 false /* expect_null_mutator_alloc_region */);
1083 }
1084 return nullptr;
1085 }
1086
1087 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1088 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1089 aligned_expand_bytes = align_up(aligned_expand_bytes,
1090 HeapRegion::GrainBytes);
1091
1092 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1093 expand_bytes, aligned_expand_bytes);
1094
1095 if (is_maximal_no_gc()) {
1096 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1097 return false;
1098 }
1099
1100 double expand_heap_start_time_sec = os::elapsedTime();
1101 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1102 assert(regions_to_expand > 0, "Must expand by at least one region");
1103
1104 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1105 if (expand_time_ms != nullptr) {
1106 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1107 }
1108
1109 assert(expanded_by > 0, "must have failed during commit.");
1110
1111 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1112 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1113 policy()->record_new_heap_size(num_regions());
1114
1115 return true;
1116 }
1117
1118 bool G1CollectedHeap::expand_single_region(uint node_index) {
1119 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1120
1121 if (expanded_by == 0) {
1122 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1123 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1124 return false;
1125 }
1126
1127 policy()->record_new_heap_size(num_regions());
1128 return true;
1129 }
1130
1131 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1132 size_t aligned_shrink_bytes =
1133 ReservedSpace::page_align_size_down(shrink_bytes);
1134 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1135 HeapRegion::GrainBytes);
1136 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1137
1138 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1139 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1140
1141 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",
1142 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1143 if (num_regions_removed > 0) {
1144 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1145 policy()->record_new_heap_size(num_regions());
1146 } else {
1147 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1148 }
1149 }
1150
1151 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1152 _verifier->verify_region_sets_optional();
1153
1154 // We should only reach here at the end of a Full GC or during Remark which
1155 // means we should not not be holding to any GC alloc regions. The method
1156 // below will make sure of that and do any remaining clean up.
1157 _allocator->abandon_gc_alloc_regions();
1158
1159 // Instead of tearing down / rebuilding the free lists here, we
1160 // could instead use the remove_all_pending() method on free_list to
1161 // remove only the ones that we need to remove.
1162 _hrm.remove_all_free_regions();
1163 shrink_helper(shrink_bytes);
1164 rebuild_region_sets(true /* free_list_only */);
1165
1166 _hrm.verify_optional();
1167 _verifier->verify_region_sets_optional();
1168 }
1169
1170 class OldRegionSetChecker : public HeapRegionSetChecker {
1171 public:
1172 void check_mt_safety() {
1173 // Master Old Set MT safety protocol:
1174 // (a) If we're at a safepoint, operations on the master old set
1175 // should be invoked:
1176 // - by the VM thread (which will serialize them), or
1177 // - by the GC workers while holding the FreeList_lock, if we're
1178 // at a safepoint for an evacuation pause (this lock is taken
1179 // anyway when an GC alloc region is retired so that a new one
1180 // is allocated from the free list), or
1181 // - by the GC workers while holding the OldSets_lock, if we're at a
1182 // safepoint for a cleanup pause.
1183 // (b) If we're not at a safepoint, operations on the master old set
1184 // should be invoked while holding the Heap_lock.
1185
1186 if (SafepointSynchronize::is_at_safepoint()) {
1187 guarantee(Thread::current()->is_VM_thread() ||
1188 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1189 "master old set MT safety protocol at a safepoint");
1190 } else {
1191 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1192 }
1193 }
1194 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1195 const char* get_description() { return "Old Regions"; }
1196 };
1197
1198 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1199 public:
1200 void check_mt_safety() {
1201 // Humongous Set MT safety protocol:
1202 // (a) If we're at a safepoint, operations on the master humongous
1203 // set should be invoked by either the VM thread (which will
1204 // serialize them) or by the GC workers while holding the
1205 // OldSets_lock.
1206 // (b) If we're not at a safepoint, operations on the master
1207 // humongous set should be invoked while holding the Heap_lock.
1208
1209 if (SafepointSynchronize::is_at_safepoint()) {
1210 guarantee(Thread::current()->is_VM_thread() ||
1211 OldSets_lock->owned_by_self(),
1212 "master humongous set MT safety protocol at a safepoint");
1213 } else {
1214 guarantee(Heap_lock->owned_by_self(),
1215 "master humongous set MT safety protocol outside a safepoint");
1216 }
1217 }
1218 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1219 const char* get_description() { return "Humongous Regions"; }
1220 };
1221
1222 G1CollectedHeap::G1CollectedHeap() :
1223 CollectedHeap(),
1224 _service_thread(nullptr),
1225 _periodic_gc_task(nullptr),
1226 _free_arena_memory_task(nullptr),
1227 _workers(nullptr),
1228 _card_table(nullptr),
1229 _collection_pause_end(Ticks::now()),
1230 _soft_ref_policy(),
1231 _old_set("Old Region Set", new OldRegionSetChecker()),
1232 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1233 _bot(nullptr),
1234 _listener(),
1235 _numa(G1NUMA::create()),
1236 _hrm(),
1237 _allocator(nullptr),
1238 _evac_failure_injector(),
1239 _verifier(nullptr),
1240 _summary_bytes_used(0),
1241 _bytes_used_during_gc(0),
1242 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1243 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1244 _monitoring_support(nullptr),
1245 _num_humongous_objects(0),
1246 _num_humongous_reclaim_candidates(0),
1247 _hr_printer(),
1248 _collector_state(),
1249 _old_marking_cycles_started(0),
1250 _old_marking_cycles_completed(0),
1251 _eden(),
1252 _survivor(),
1253 _gc_timer_stw(new STWGCTimer()),
1254 _gc_tracer_stw(new G1NewTracer()),
1255 _policy(new G1Policy(_gc_timer_stw)),
1256 _heap_sizing_policy(nullptr),
1257 _collection_set(this, _policy),
1258 _rem_set(nullptr),
1259 _card_set_config(),
1260 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1261 _cm(nullptr),
1262 _cm_thread(nullptr),
1263 _cr(nullptr),
1264 _task_queues(nullptr),
1265 _ref_processor_stw(nullptr),
1266 _is_alive_closure_stw(this),
1267 _is_subject_to_discovery_stw(this),
1268 _ref_processor_cm(nullptr),
1269 _is_alive_closure_cm(this),
1270 _is_subject_to_discovery_cm(this),
1271 _region_attr() {
1272
1273 _verifier = new G1HeapVerifier(this);
1274
1275 _allocator = new G1Allocator(this);
1276
1277 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1278
1279 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1280
1281 // Override the default _filler_array_max_size so that no humongous filler
1282 // objects are created.
1283 _filler_array_max_size = _humongous_object_threshold_in_words;
1284
1285 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1286 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1287
1288 uint n_queues = ParallelGCThreads;
1289 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1290
1291 for (uint i = 0; i < n_queues; i++) {
1292 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1293 _task_queues->register_queue(i, q);
1294 }
1295
1296 _gc_tracer_stw->initialize();
1297
1298 guarantee(_task_queues != nullptr, "task_queues allocation failure.");
1299 }
1300
1301 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1302 size_t size,
1303 size_t translation_factor) {
1304 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1305 // Allocate a new reserved space, preferring to use large pages.
1306 ReservedSpace rs(size, preferred_page_size);
1307 size_t page_size = rs.page_size();
1308 G1RegionToSpaceMapper* result =
1309 G1RegionToSpaceMapper::create_mapper(rs,
1310 size,
1311 page_size,
1312 HeapRegion::GrainBytes,
1313 translation_factor,
1314 mtGC);
1315
1316 os::trace_page_sizes_for_requested_size(description,
1317 size,
1318 page_size,
1319 preferred_page_size,
1320 rs.base(),
1321 rs.size());
1322
1323 return result;
1324 }
1325
1326 jint G1CollectedHeap::initialize_concurrent_refinement() {
1327 jint ecode = JNI_OK;
1328 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1329 return ecode;
1330 }
1331
1332 jint G1CollectedHeap::initialize_service_thread() {
1333 _service_thread = new G1ServiceThread();
1334 if (_service_thread->osthread() == nullptr) {
1335 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1336 return JNI_ENOMEM;
1337 }
1338 return JNI_OK;
1339 }
1340
1341 jint G1CollectedHeap::initialize() {
1342
1343 // Necessary to satisfy locking discipline assertions.
1344
1345 MutexLocker x(Heap_lock);
1346
1347 // While there are no constraints in the GC code that HeapWordSize
1348 // be any particular value, there are multiple other areas in the
1349 // system which believe this to be true (e.g. oop->object_size in some
1350 // cases incorrectly returns the size in wordSize units rather than
1351 // HeapWordSize).
1352 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1353
1354 size_t init_byte_size = InitialHeapSize;
1355 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1356
1357 // Ensure that the sizes are properly aligned.
1358 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1359 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1360 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1361
1362 // Reserve the maximum.
1363
1364 // When compressed oops are enabled, the preferred heap base
1365 // is calculated by subtracting the requested size from the
1366 // 32Gb boundary and using the result as the base address for
1367 // heap reservation. If the requested size is not aligned to
1368 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1369 // into the ReservedHeapSpace constructor) then the actual
1370 // base of the reserved heap may end up differing from the
1371 // address that was requested (i.e. the preferred heap base).
1372 // If this happens then we could end up using a non-optimal
1373 // compressed oops mode.
1374
1375 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1376 HeapAlignment);
1377
1378 initialize_reserved_region(heap_rs);
1379
1380 // Create the barrier set for the entire reserved region.
1381 G1CardTable* ct = new G1CardTable(heap_rs.region());
1382 G1BarrierSet* bs = new G1BarrierSet(ct);
1383 bs->initialize();
1384 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1385 BarrierSet::set_barrier_set(bs);
1386 _card_table = ct;
1387
1388 {
1389 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1390 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1391 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1392 }
1393
1394 // Create space mappers.
1395 size_t page_size = heap_rs.page_size();
1396 G1RegionToSpaceMapper* heap_storage =
1397 G1RegionToSpaceMapper::create_mapper(heap_rs,
1398 heap_rs.size(),
1399 page_size,
1400 HeapRegion::GrainBytes,
1401 1,
1402 mtJavaHeap);
1403 if(heap_storage == nullptr) {
1404 vm_shutdown_during_initialization("Could not initialize G1 heap");
1405 return JNI_ERR;
1406 }
1407
1408 os::trace_page_sizes("Heap",
1409 MinHeapSize,
1410 reserved_byte_size,
1411 page_size,
1412 heap_rs.base(),
1413 heap_rs.size());
1414 heap_storage->set_mapping_changed_listener(&_listener);
1415
1416 // Create storage for the BOT, card table and the bitmap.
1417 G1RegionToSpaceMapper* bot_storage =
1418 create_aux_memory_mapper("Block Offset Table",
1419 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1420 G1BlockOffsetTable::heap_map_factor());
1421
1422 G1RegionToSpaceMapper* cardtable_storage =
1423 create_aux_memory_mapper("Card Table",
1424 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1425 G1CardTable::heap_map_factor());
1426
1427 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1428 G1RegionToSpaceMapper* bitmap_storage =
1429 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1430
1431 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1432 _card_table->initialize(cardtable_storage);
1433
1434 // 6843694 - ensure that the maximum region index can fit
1435 // in the remembered set structures.
1436 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1437 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1438
1439 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1440 // start within the first card.
1441 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1442 G1FromCardCache::initialize(max_reserved_regions());
1443 // Also create a G1 rem set.
1444 _rem_set = new G1RemSet(this, _card_table);
1445 _rem_set->initialize(max_reserved_regions());
1446
1447 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1448 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1449 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1450 "too many cards per region");
1451
1452 HeapRegionRemSet::initialize(_reserved);
1453
1454 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1455
1456 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1457
1458 {
1459 size_t granularity = HeapRegion::GrainBytes;
1460
1461 _region_attr.initialize(reserved(), granularity);
1462 }
1463
1464 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1465 if (_workers == nullptr) {
1466 return JNI_ENOMEM;
1467 }
1468 _workers->initialize_workers();
1469
1470 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1471
1472 // Create the G1ConcurrentMark data structure and thread.
1473 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1474 _cm = new G1ConcurrentMark(this, bitmap_storage);
1475 _cm_thread = _cm->cm_thread();
1476
1477 // Now expand into the initial heap size.
1478 if (!expand(init_byte_size, _workers)) {
1479 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1480 return JNI_ENOMEM;
1481 }
1482
1483 // Perform any initialization actions delegated to the policy.
1484 policy()->init(this, &_collection_set);
1485
1486 jint ecode = initialize_concurrent_refinement();
1487 if (ecode != JNI_OK) {
1488 return ecode;
1489 }
1490
1491 ecode = initialize_service_thread();
1492 if (ecode != JNI_OK) {
1493 return ecode;
1494 }
1495
1496 // Create and schedule the periodic gc task on the service thread.
1497 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1498 _service_thread->register_task(_periodic_gc_task);
1499
1500 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1501 _service_thread->register_task(_free_arena_memory_task);
1502
1503 // Here we allocate the dummy HeapRegion that is required by the
1504 // G1AllocRegion class.
1505 HeapRegion* dummy_region = _hrm.get_dummy_region();
1506
1507 // We'll re-use the same region whether the alloc region will
1508 // require BOT updates or not and, if it doesn't, then a non-young
1509 // region will complain that it cannot support allocations without
1510 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1511 dummy_region->set_eden();
1512 // Make sure it's full.
1513 dummy_region->set_top(dummy_region->end());
1514 G1AllocRegion::setup(this, dummy_region);
1515
1516 _allocator->init_mutator_alloc_regions();
1517
1518 // Do create of the monitoring and management support so that
1519 // values in the heap have been properly initialized.
1520 _monitoring_support = new G1MonitoringSupport(this);
1521
1522 _collection_set.initialize(max_reserved_regions());
1523
1524 evac_failure_injector()->reset();
1525
1526 G1InitLogger::print();
1527
1528 SlidingForwarding::initialize(heap_rs.region(), HeapRegion::GrainWords);
1529
1530 return JNI_OK;
1531 }
1532
1533 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1534 return _cm_thread->should_terminate();
1535 }
1536
1537 void G1CollectedHeap::stop() {
1538 // Stop all concurrent threads. We do this to make sure these threads
1539 // do not continue to execute and access resources (e.g. logging)
1540 // that are destroyed during shutdown.
1541 _cr->stop();
1542 _service_thread->stop();
1543 _cm_thread->stop();
1544 }
1545
1546 void G1CollectedHeap::safepoint_synchronize_begin() {
1547 SuspendibleThreadSet::synchronize();
1548 }
1549
1550 void G1CollectedHeap::safepoint_synchronize_end() {
1551 SuspendibleThreadSet::desynchronize();
1552 }
1553
1554 void G1CollectedHeap::post_initialize() {
1555 CollectedHeap::post_initialize();
1556 ref_processing_init();
1557 }
1558
1559 void G1CollectedHeap::ref_processing_init() {
1560 // Reference processing in G1 currently works as follows:
1561 //
1562 // * There are two reference processor instances. One is
1563 // used to record and process discovered references
1564 // during concurrent marking; the other is used to
1565 // record and process references during STW pauses
1566 // (both full and incremental).
1567 // * Both ref processors need to 'span' the entire heap as
1568 // the regions in the collection set may be dotted around.
1569 //
1570 // * For the concurrent marking ref processor:
1571 // * Reference discovery is enabled at concurrent start.
1572 // * Reference discovery is disabled and the discovered
1573 // references processed etc during remarking.
1574 // * Reference discovery is MT (see below).
1575 // * Reference discovery requires a barrier (see below).
1576 // * Reference processing may or may not be MT
1577 // (depending on the value of ParallelRefProcEnabled
1578 // and ParallelGCThreads).
1579 // * A full GC disables reference discovery by the CM
1580 // ref processor and abandons any entries on it's
1581 // discovered lists.
1582 //
1583 // * For the STW processor:
1584 // * Non MT discovery is enabled at the start of a full GC.
1585 // * Processing and enqueueing during a full GC is non-MT.
1586 // * During a full GC, references are processed after marking.
1587 //
1588 // * Discovery (may or may not be MT) is enabled at the start
1589 // of an incremental evacuation pause.
1590 // * References are processed near the end of a STW evacuation pause.
1591 // * For both types of GC:
1592 // * Discovery is atomic - i.e. not concurrent.
1593 // * Reference discovery will not need a barrier.
1594
1595 // Concurrent Mark ref processor
1596 _ref_processor_cm =
1597 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1598 ParallelGCThreads, // degree of mt processing
1599 // We discover with the gc worker threads during Remark, so both
1600 // thread counts must be considered for discovery.
1601 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1602 true, // Reference discovery is concurrent
1603 &_is_alive_closure_cm); // is alive closure
1604
1605 // STW ref processor
1606 _ref_processor_stw =
1607 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1608 ParallelGCThreads, // degree of mt processing
1609 ParallelGCThreads, // degree of mt discovery
1610 false, // Reference discovery is not concurrent
1611 &_is_alive_closure_stw); // is alive closure
1612 }
1613
1614 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1615 return &_soft_ref_policy;
1616 }
1617
1618 size_t G1CollectedHeap::capacity() const {
1619 return _hrm.length() * HeapRegion::GrainBytes;
1620 }
1621
1622 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1623 return _hrm.total_free_bytes();
1624 }
1625
1626 // Computes the sum of the storage used by the various regions.
1627 size_t G1CollectedHeap::used() const {
1628 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1629 return result;
1630 }
1631
1632 size_t G1CollectedHeap::used_unlocked() const {
1633 return _summary_bytes_used;
1634 }
1635
1636 class SumUsedClosure: public HeapRegionClosure {
1637 size_t _used;
1638 public:
1639 SumUsedClosure() : _used(0) {}
1640 bool do_heap_region(HeapRegion* r) {
1641 _used += r->used();
1642 return false;
1643 }
1644 size_t result() { return _used; }
1645 };
1646
1647 size_t G1CollectedHeap::recalculate_used() const {
1648 SumUsedClosure blk;
1649 heap_region_iterate(&blk);
1650 return blk.result();
1651 }
1652
1653 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1654 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1655 }
1656
1657 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1658 switch (cause) {
1659 case GCCause::_g1_humongous_allocation: return true;
1660 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1661 case GCCause::_wb_breakpoint: return true;
1662 case GCCause::_codecache_GC_aggressive: return true;
1663 case GCCause::_codecache_GC_threshold: return true;
1664 default: return is_user_requested_concurrent_full_gc(cause);
1665 }
1666 }
1667
1668 void G1CollectedHeap::increment_old_marking_cycles_started() {
1669 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1670 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1671 "Wrong marking cycle count (started: %d, completed: %d)",
1672 _old_marking_cycles_started, _old_marking_cycles_completed);
1673
1674 _old_marking_cycles_started++;
1675 }
1676
1677 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1678 bool whole_heap_examined) {
1679 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1680
1681 // We assume that if concurrent == true, then the caller is a
1682 // concurrent thread that was joined the Suspendible Thread
1683 // Set. If there's ever a cheap way to check this, we should add an
1684 // assert here.
1685
1686 // Given that this method is called at the end of a Full GC or of a
1687 // concurrent cycle, and those can be nested (i.e., a Full GC can
1688 // interrupt a concurrent cycle), the number of full collections
1689 // completed should be either one (in the case where there was no
1690 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1691 // behind the number of full collections started.
1692
1693 // This is the case for the inner caller, i.e. a Full GC.
1694 assert(concurrent ||
1695 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1696 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1697 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1698 "is inconsistent with _old_marking_cycles_completed = %u",
1699 _old_marking_cycles_started, _old_marking_cycles_completed);
1700
1701 // This is the case for the outer caller, i.e. the concurrent cycle.
1702 assert(!concurrent ||
1703 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1704 "for outer caller (concurrent cycle): "
1705 "_old_marking_cycles_started = %u "
1706 "is inconsistent with _old_marking_cycles_completed = %u",
1707 _old_marking_cycles_started, _old_marking_cycles_completed);
1708
1709 _old_marking_cycles_completed += 1;
1710 if (whole_heap_examined) {
1711 // Signal that we have completed a visit to all live objects.
1712 record_whole_heap_examined_timestamp();
1713 }
1714
1715 // We need to clear the "in_progress" flag in the CM thread before
1716 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1717 // is set) so that if a waiter requests another System.gc() it doesn't
1718 // incorrectly see that a marking cycle is still in progress.
1719 if (concurrent) {
1720 _cm_thread->set_idle();
1721 }
1722
1723 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1724 // for a full GC to finish that their wait is over.
1725 ml.notify_all();
1726 }
1727
1728 // Helper for collect().
1729 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1730 MutexLocker ml(Heap_lock);
1731 return G1GCCounters(g1h);
1732 }
1733
1734 void G1CollectedHeap::collect(GCCause::Cause cause) {
1735 try_collect(cause, collection_counters(this));
1736 }
1737
1738 // Return true if (x < y) with allowance for wraparound.
1739 static bool gc_counter_less_than(uint x, uint y) {
1740 return (x - y) > (UINT_MAX/2);
1741 }
1742
1743 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1744 // Macro so msg printing is format-checked.
1745 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1746 do { \
1747 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1748 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1749 ResourceMark rm; /* For thread name. */ \
1750 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1751 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1752 Thread::current()->name(), \
1753 GCCause::to_string(cause)); \
1754 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1755 } \
1756 } while (0)
1757
1758 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1759 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1760
1761 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1762 uint gc_counter,
1763 uint old_marking_started_before) {
1764 assert_heap_not_locked();
1765 assert(should_do_concurrent_full_gc(cause),
1766 "Non-concurrent cause %s", GCCause::to_string(cause));
1767
1768 for (uint i = 1; true; ++i) {
1769 // Try to schedule concurrent start evacuation pause that will
1770 // start a concurrent cycle.
1771 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1772 VM_G1TryInitiateConcMark op(gc_counter, cause);
1773 VMThread::execute(&op);
1774
1775 // Request is trivially finished.
1776 if (cause == GCCause::_g1_periodic_collection) {
1777 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1778 return op.gc_succeeded();
1779 }
1780
1781 // If VMOp skipped initiating concurrent marking cycle because
1782 // we're terminating, then we're done.
1783 if (op.terminating()) {
1784 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1785 return false;
1786 }
1787
1788 // Lock to get consistent set of values.
1789 uint old_marking_started_after;
1790 uint old_marking_completed_after;
1791 {
1792 MutexLocker ml(Heap_lock);
1793 // Update gc_counter for retrying VMOp if needed. Captured here to be
1794 // consistent with the values we use below for termination tests. If
1795 // a retry is needed after a possible wait, and another collection
1796 // occurs in the meantime, it will cause our retry to be skipped and
1797 // we'll recheck for termination with updated conditions from that
1798 // more recent collection. That's what we want, rather than having
1799 // our retry possibly perform an unnecessary collection.
1800 gc_counter = total_collections();
1801 old_marking_started_after = _old_marking_cycles_started;
1802 old_marking_completed_after = _old_marking_cycles_completed;
1803 }
1804
1805 if (cause == GCCause::_wb_breakpoint) {
1806 if (op.gc_succeeded()) {
1807 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1808 return true;
1809 }
1810 // When _wb_breakpoint there can't be another cycle or deferred.
1811 assert(!op.cycle_already_in_progress(), "invariant");
1812 assert(!op.whitebox_attached(), "invariant");
1813 // Concurrent cycle attempt might have been cancelled by some other
1814 // collection, so retry. Unlike other cases below, we want to retry
1815 // even if cancelled by a STW full collection, because we really want
1816 // to start a concurrent cycle.
1817 if (old_marking_started_before != old_marking_started_after) {
1818 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1819 old_marking_started_before = old_marking_started_after;
1820 }
1821 } else if (!GCCause::is_user_requested_gc(cause)) {
1822 // For an "automatic" (not user-requested) collection, we just need to
1823 // ensure that progress is made.
1824 //
1825 // Request is finished if any of
1826 // (1) the VMOp successfully performed a GC,
1827 // (2) a concurrent cycle was already in progress,
1828 // (3) whitebox is controlling concurrent cycles,
1829 // (4) a new cycle was started (by this thread or some other), or
1830 // (5) a Full GC was performed.
1831 // Cases (4) and (5) are detected together by a change to
1832 // _old_marking_cycles_started.
1833 //
1834 // Note that (1) does not imply (4). If we're still in the mixed
1835 // phase of an earlier concurrent collection, the request to make the
1836 // collection a concurrent start won't be honored. If we don't check for
1837 // both conditions we'll spin doing back-to-back collections.
1838 if (op.gc_succeeded() ||
1839 op.cycle_already_in_progress() ||
1840 op.whitebox_attached() ||
1841 (old_marking_started_before != old_marking_started_after)) {
1842 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1843 return true;
1844 }
1845 } else { // User-requested GC.
1846 // For a user-requested collection, we want to ensure that a complete
1847 // full collection has been performed before returning, but without
1848 // waiting for more than needed.
1849
1850 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1851 // new cycle was started. That's good, because it's not clear what we
1852 // should do otherwise. Trying again just does back to back GCs.
1853 // Can't wait for someone else to start a cycle. And returning fails
1854 // to meet the goal of ensuring a full collection was performed.
1855 assert(!op.gc_succeeded() ||
1856 (old_marking_started_before != old_marking_started_after),
1857 "invariant: succeeded %s, started before %u, started after %u",
1858 BOOL_TO_STR(op.gc_succeeded()),
1859 old_marking_started_before, old_marking_started_after);
1860
1861 // Request is finished if a full collection (concurrent or stw)
1862 // was started after this request and has completed, e.g.
1863 // started_before < completed_after.
1864 if (gc_counter_less_than(old_marking_started_before,
1865 old_marking_completed_after)) {
1866 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1867 return true;
1868 }
1869
1870 if (old_marking_started_after != old_marking_completed_after) {
1871 // If there is an in-progress cycle (possibly started by us), then
1872 // wait for that cycle to complete, e.g.
1873 // while completed_now < started_after.
1874 LOG_COLLECT_CONCURRENTLY(cause, "wait");
1875 MonitorLocker ml(G1OldGCCount_lock);
1876 while (gc_counter_less_than(_old_marking_cycles_completed,
1877 old_marking_started_after)) {
1878 ml.wait();
1879 }
1880 // Request is finished if the collection we just waited for was
1881 // started after this request.
1882 if (old_marking_started_before != old_marking_started_after) {
1883 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
1884 return true;
1885 }
1886 }
1887
1888 // If VMOp was successful then it started a new cycle that the above
1889 // wait &etc should have recognized as finishing this request. This
1890 // differs from a non-user-request, where gc_succeeded does not imply
1891 // a new cycle was started.
1892 assert(!op.gc_succeeded(), "invariant");
1893
1894 if (op.cycle_already_in_progress()) {
1895 // If VMOp failed because a cycle was already in progress, it
1896 // is now complete. But it didn't finish this user-requested
1897 // GC, so try again.
1898 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
1899 continue;
1900 } else if (op.whitebox_attached()) {
1901 // If WhiteBox wants control, wait for notification of a state
1902 // change in the controller, then try again. Don't wait for
1903 // release of control, since collections may complete while in
1904 // control. Note: This won't recognize a STW full collection
1905 // while waiting; we can't wait on multiple monitors.
1906 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
1907 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
1908 if (ConcurrentGCBreakpoints::is_controlled()) {
1909 ml.wait();
1910 }
1911 continue;
1912 }
1913 }
1914
1915 // Collection failed and should be retried.
1916 assert(op.transient_failure(), "invariant");
1917
1918 if (GCLocker::is_active_and_needs_gc()) {
1919 // If GCLocker is active, wait until clear before retrying.
1920 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
1921 GCLocker::stall_until_clear();
1922 }
1923
1924 LOG_COLLECT_CONCURRENTLY(cause, "retry");
1925 }
1926 }
1927
1928 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause,
1929 const G1GCCounters& counters_before) {
1930 assert_heap_not_locked();
1931
1932 while(true) {
1933 VM_G1CollectFull op(counters_before.total_collections(),
1934 counters_before.total_full_collections(),
1935 cause);
1936 VMThread::execute(&op);
1937
1938 // Request is trivially finished.
1939 if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) {
1940 return op.gc_succeeded();
1941 }
1942
1943 {
1944 MutexLocker ml(Heap_lock);
1945 if (counters_before.total_full_collections() != total_full_collections()) {
1946 return true;
1947 }
1948 }
1949
1950 if (GCLocker::is_active_and_needs_gc()) {
1951 // If GCLocker is active, wait until clear before retrying.
1952 GCLocker::stall_until_clear();
1953 }
1954 }
1955 }
1956
1957 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
1958 const G1GCCounters& counters_before) {
1959 if (should_do_concurrent_full_gc(cause)) {
1960 return try_collect_concurrently(cause,
1961 counters_before.total_collections(),
1962 counters_before.old_marking_cycles_started());
1963 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
1964 // Indicate failure to be consistent with VMOp failure due to
1965 // another collection slipping in after our gc_count but before
1966 // our request is processed.
1967 return false;
1968 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
1969 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1970
1971 // Schedule a standard evacuation pause. We're setting word_size
1972 // to 0 which means that we are not requesting a post-GC allocation.
1973 VM_G1CollectForAllocation op(0, /* word_size */
1974 counters_before.total_collections(),
1975 cause);
1976 VMThread::execute(&op);
1977 return op.gc_succeeded();
1978 } else {
1979 // Schedule a Full GC.
1980 return try_collect_fullgc(cause, counters_before);
1981 }
1982 }
1983
1984 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
1985 GCCauseSetter x(this, gc_cause);
1986
1987 // At this point we are supposed to start a concurrent cycle. We
1988 // will do so if one is not already in progress.
1989 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
1990 if (should_start) {
1991 do_collection_pause_at_safepoint();
1992 }
1993 }
1994
1995 bool G1CollectedHeap::is_in(const void* p) const {
1996 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
1997 }
1998
1999 // Iteration functions.
2000
2001 // Iterates an ObjectClosure over all objects within a HeapRegion.
2002
2003 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2004 ObjectClosure* _cl;
2005 public:
2006 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2007 bool do_heap_region(HeapRegion* r) {
2008 if (!r->is_continues_humongous()) {
2009 r->object_iterate(_cl);
2010 }
2011 return false;
2012 }
2013 };
2014
2015 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2016 IterateObjectClosureRegionClosure blk(cl);
2017 heap_region_iterate(&blk);
2018 }
2019
2020 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2021 private:
2022 G1CollectedHeap* _heap;
2023 HeapRegionClaimer _claimer;
2024
2025 public:
2026 G1ParallelObjectIterator(uint thread_num) :
2027 _heap(G1CollectedHeap::heap()),
2028 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2029
2030 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2031 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2032 }
2033 };
2034
2035 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2036 return new G1ParallelObjectIterator(thread_num);
2037 }
2038
2039 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2040 IterateObjectClosureRegionClosure blk(cl);
2041 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2042 }
2043
2044 void G1CollectedHeap::keep_alive(oop obj) {
2045 G1BarrierSet::enqueue_preloaded(obj);
2046 }
2047
2048 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2049 _hrm.iterate(cl);
2050 }
2051
2052 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2053 _hrm.iterate(cl);
2054 }
2055
2056 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2057 HeapRegionClaimer *hrclaimer,
2058 uint worker_id) const {
2059 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2060 }
2061
2062 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2063 HeapRegionClaimer *hrclaimer) const {
2064 _hrm.par_iterate(cl, hrclaimer, 0);
2065 }
2066
2067 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2068 _collection_set.iterate(cl);
2069 }
2070
2071 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2072 HeapRegionClaimer* hr_claimer,
2073 uint worker_id) {
2074 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2075 }
2076
2077 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2078 HeapRegionClaimer* hr_claimer,
2079 uint worker_id) {
2080 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2081 }
2082
2083 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2084 HeapRegionClaimer* hr_claimer,
2085 const uint regions[],
2086 size_t length,
2087 uint worker_id) const {
2088 assert_at_safepoint();
2089 if (length == 0) {
2090 return;
2091 }
2092 uint total_workers = workers()->active_workers();
2093
2094 size_t start_pos = (worker_id * length) / total_workers;
2095 size_t cur_pos = start_pos;
2096
2097 do {
2098 uint region_idx = regions[cur_pos];
2099 if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) {
2100 HeapRegion* r = region_at(region_idx);
2101 bool result = cl->do_heap_region(r);
2102 guarantee(!result, "Must not cancel iteration");
2103 }
2104
2105 cur_pos++;
2106 if (cur_pos == length) {
2107 cur_pos = 0;
2108 }
2109 } while (cur_pos != start_pos);
2110 }
2111
2112 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2113 HeapRegion* hr = heap_region_containing(addr);
2114 // The CollectedHeap API requires us to not fail for any given address within
2115 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2116 // outside of the allocated area.
2117 if (addr >= hr->top()) {
2118 return nullptr;
2119 }
2120 return hr->block_start(addr);
2121 }
2122
2123 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2124 HeapRegion* hr = heap_region_containing(addr);
2125 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2126 }
2127
2128 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2129 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2130 }
2131
2132 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2133 return _eden.length() * HeapRegion::GrainBytes;
2134 }
2135
2136 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2137 // must be equal to the humongous object limit.
2138 size_t G1CollectedHeap::max_tlab_size() const {
2139 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2140 }
2141
2142 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2143 return _allocator->unsafe_max_tlab_alloc();
2144 }
2145
2146 size_t G1CollectedHeap::max_capacity() const {
2147 return max_regions() * HeapRegion::GrainBytes;
2148 }
2149
2150 void G1CollectedHeap::prepare_for_verify() {
2151 _verifier->prepare_for_verify();
2152 }
2153
2154 void G1CollectedHeap::verify(VerifyOption vo) {
2155 _verifier->verify(vo);
2156 }
2157
2158 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2159 return true;
2160 }
2161
2162 class PrintRegionClosure: public HeapRegionClosure {
2163 outputStream* _st;
2164 public:
2165 PrintRegionClosure(outputStream* st) : _st(st) {}
2166 bool do_heap_region(HeapRegion* r) {
2167 r->print_on(_st);
2168 return false;
2169 }
2170 };
2171
2172 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2173 const HeapRegion* hr,
2174 const VerifyOption vo) const {
2175 switch (vo) {
2176 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2177 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2178 default: ShouldNotReachHere();
2179 }
2180 return false; // keep some compilers happy
2181 }
2182
2183 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2184 const VerifyOption vo) const {
2185 switch (vo) {
2186 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2187 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2188 default: ShouldNotReachHere();
2189 }
2190 return false; // keep some compilers happy
2191 }
2192
2193 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) {
2194 GCLocker::lock_critical(thread);
2195 }
2196
2197 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
2198 GCLocker::unlock_critical(thread);
2199 }
2200
2201 void G1CollectedHeap::print_heap_regions() const {
2202 LogTarget(Trace, gc, heap, region) lt;
2203 if (lt.is_enabled()) {
2204 LogStream ls(lt);
2205 print_regions_on(&ls);
2206 }
2207 }
2208
2209 void G1CollectedHeap::print_on(outputStream* st) const {
2210 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2211 st->print(" %-20s", "garbage-first heap");
2212 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2213 capacity()/K, heap_used/K);
2214 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2215 p2i(_hrm.reserved().start()),
2216 p2i(_hrm.reserved().end()));
2217 st->cr();
2218 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2219 uint young_regions = young_regions_count();
2220 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2221 (size_t) young_regions * HeapRegion::GrainBytes / K);
2222 uint survivor_regions = survivor_regions_count();
2223 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2224 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2225 st->cr();
2226 if (_numa->is_enabled()) {
2227 uint num_nodes = _numa->num_active_nodes();
2228 st->print(" remaining free region(s) on each NUMA node: ");
2229 const int* node_ids = _numa->node_ids();
2230 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2231 uint num_free_regions = _hrm.num_free_regions(node_index);
2232 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2233 }
2234 st->cr();
2235 }
2236 MetaspaceUtils::print_on(st);
2237 }
2238
2239 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2240 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2241 "HS=humongous(starts), HC=humongous(continues), "
2242 "CS=collection set, F=free, "
2243 "TAMS=top-at-mark-start, "
2244 "PB=parsable bottom");
2245 PrintRegionClosure blk(st);
2246 heap_region_iterate(&blk);
2247 }
2248
2249 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2250 print_on(st);
2251
2252 // Print the per-region information.
2253 st->cr();
2254 print_regions_on(st);
2255 }
2256
2257 void G1CollectedHeap::print_on_error(outputStream* st) const {
2258 this->CollectedHeap::print_on_error(st);
2259
2260 if (_cm != nullptr) {
2261 st->cr();
2262 _cm->print_on_error(st);
2263 }
2264 }
2265
2266 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2267 workers()->threads_do(tc);
2268 tc->do_thread(_cm_thread);
2269 _cm->threads_do(tc);
2270 _cr->threads_do(tc);
2271 tc->do_thread(_service_thread);
2272 }
2273
2274 void G1CollectedHeap::print_tracing_info() const {
2275 rem_set()->print_summary_info();
2276 concurrent_mark()->print_summary_info();
2277 }
2278
2279 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2280 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2281 }
2282
2283 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2284
2285 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2286 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2287 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2288 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2289
2290 size_t eden_capacity_bytes =
2291 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2292
2293 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2294 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2295 survivor_used_bytes, old_gen_used_bytes, num_regions());
2296 }
2297
2298 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2299 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2300 stats->unused(), stats->used(), stats->region_end_waste(),
2301 stats->regions_filled(), stats->num_plab_filled(),
2302 stats->direct_allocated(), stats->num_direct_allocated(),
2303 stats->failure_used(), stats->failure_waste());
2304 }
2305
2306 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2307 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2308 gc_tracer->report_gc_heap_summary(when, heap_summary);
2309
2310 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2311 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2312 }
2313
2314 void G1CollectedHeap::gc_prologue(bool full) {
2315 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2316
2317 // Update common counters.
2318 increment_total_collections(full /* full gc */);
2319 if (full || collector_state()->in_concurrent_start_gc()) {
2320 increment_old_marking_cycles_started();
2321 }
2322 }
2323
2324 void G1CollectedHeap::gc_epilogue(bool full) {
2325 // Update common counters.
2326 if (full) {
2327 // Update the number of full collections that have been completed.
2328 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2329 }
2330
2331 #if COMPILER2_OR_JVMCI
2332 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2333 #endif
2334
2335 // We have just completed a GC. Update the soft reference
2336 // policy with the new heap occupancy
2337 Universe::heap()->update_capacity_and_used_at_gc();
2338
2339 _collection_pause_end = Ticks::now();
2340
2341 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2342 &_collection_set_candidates_card_set_stats);
2343 }
2344
2345 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2346 return _hrm.uncommit_inactive_regions(region_limit);
2347 }
2348
2349 bool G1CollectedHeap::has_uncommittable_regions() {
2350 return _hrm.has_inactive_regions();
2351 }
2352
2353 void G1CollectedHeap::uncommit_regions_if_necessary() {
2354 if (has_uncommittable_regions()) {
2355 G1UncommitRegionTask::enqueue();
2356 }
2357 }
2358
2359 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2360 LogTarget(Trace, gc, heap, verify) lt;
2361
2362 if (lt.is_enabled()) {
2363 LogStream ls(lt);
2364 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2365 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2366 heap_region_iterate(&cl);
2367 }
2368 }
2369
2370 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2371 uint gc_count_before,
2372 bool* succeeded,
2373 GCCause::Cause gc_cause) {
2374 assert_heap_not_locked_and_not_at_safepoint();
2375 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2376 VMThread::execute(&op);
2377
2378 HeapWord* result = op.result();
2379 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2380 assert(result == nullptr || ret_succeeded,
2381 "the result should be null if the VM did not succeed");
2382 *succeeded = ret_succeeded;
2383
2384 assert_heap_not_locked();
2385 return result;
2386 }
2387
2388 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2389 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2390
2391 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2392 if (concurrent_operation_is_full_mark) {
2393 _cm->post_concurrent_mark_start();
2394 _cm_thread->start_full_mark();
2395 } else {
2396 _cm->post_concurrent_undo_start();
2397 _cm_thread->start_undo_mark();
2398 }
2399 CGC_lock->notify();
2400 }
2401
2402 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2403 // We don't nominate objects with many remembered set entries, on
2404 // the assumption that such objects are likely still live.
2405 HeapRegionRemSet* rem_set = r->rem_set();
2406
2407 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2408 }
2409
2410 #ifndef PRODUCT
2411 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2412 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2413 public:
2414 virtual bool do_heap_region(HeapRegion* r) {
2415 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2416 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2417 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2418 "Region %u remset tracking status (%s) different to region attribute (%s)",
2419 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2420 return false;
2421 }
2422 } cl;
2423 heap_region_iterate(&cl);
2424 }
2425 #endif
2426
2427 void G1CollectedHeap::start_new_collection_set() {
2428 collection_set()->start_incremental_building();
2429
2430 clear_region_attr();
2431
2432 guarantee(_eden.length() == 0, "eden should have been cleared");
2433 policy()->transfer_survivors_to_cset(survivor());
2434
2435 // We redo the verification but now wrt to the new CSet which
2436 // has just got initialized after the previous CSet was freed.
2437 _cm->verify_no_collection_set_oops();
2438 }
2439
2440 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2441 if (collector_state()->in_concurrent_start_gc()) {
2442 return G1HeapVerifier::G1VerifyConcurrentStart;
2443 } else if (collector_state()->in_young_only_phase()) {
2444 return G1HeapVerifier::G1VerifyYoungNormal;
2445 } else {
2446 return G1HeapVerifier::G1VerifyMixed;
2447 }
2448 }
2449
2450 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2451 if (!VerifyBeforeGC) {
2452 return;
2453 }
2454 if (!G1HeapVerifier::should_verify(type)) {
2455 return;
2456 }
2457 Ticks start = Ticks::now();
2458 _verifier->prepare_for_verify();
2459 _verifier->verify_region_sets_optional();
2460 _verifier->verify_dirty_young_regions();
2461 _verifier->verify_before_gc();
2462 verify_numa_regions("GC Start");
2463 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2464 }
2465
2466 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2467 if (!VerifyAfterGC) {
2468 return;
2469 }
2470 if (!G1HeapVerifier::should_verify(type)) {
2471 return;
2472 }
2473 Ticks start = Ticks::now();
2474 _verifier->verify_after_gc();
2475 verify_numa_regions("GC End");
2476 _verifier->verify_region_sets_optional();
2477 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2478 }
2479
2480 void G1CollectedHeap::expand_heap_after_young_collection(){
2481 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2482 if (expand_bytes > 0) {
2483 // No need for an ergo logging here,
2484 // expansion_amount() does this when it returns a value > 0.
2485 double expand_ms = 0.0;
2486 if (!expand(expand_bytes, _workers, &expand_ms)) {
2487 // We failed to expand the heap. Cannot do anything about it.
2488 }
2489 phase_times()->record_expand_heap_time(expand_ms);
2490 }
2491 }
2492
2493 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2494 assert_at_safepoint_on_vm_thread();
2495 guarantee(!is_gc_active(), "collection is not reentrant");
2496
2497 if (GCLocker::check_active_before_gc()) {
2498 return false;
2499 }
2500
2501 do_collection_pause_at_safepoint_helper();
2502 return true;
2503 }
2504
2505 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2506 // This summary needs to be printed before incrementing total collections.
2507 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2508 _g1h->total_collections(),
2509 true /* show_thread_times */);
2510 _g1h->print_heap_before_gc();
2511 _g1h->print_heap_regions();
2512 }
2513
2514 G1HeapPrinterMark::~G1HeapPrinterMark() {
2515 _g1h->policy()->print_age_table();
2516 _g1h->rem_set()->print_coarsen_stats();
2517 // We are at the end of the GC. Total collections has already been increased.
2518 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2519 _g1h->total_collections() - 1,
2520 false /* show_thread_times */);
2521
2522 _heap_transition.print();
2523 _g1h->print_heap_regions();
2524 _g1h->print_heap_after_gc();
2525 // Print NUMA statistics.
2526 _g1h->numa()->print_statistics();
2527 }
2528
2529 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2530 _timer(timer), _tracer(tracer) {
2531
2532 _timer->register_gc_start();
2533 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2534 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2535 }
2536
2537 G1JFRTracerMark::~G1JFRTracerMark() {
2538 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2539 _timer->register_gc_end();
2540 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2541 }
2542
2543 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2544 Ticks start = Ticks::now();
2545
2546 _survivor_evac_stats.adjust_desired_plab_size();
2547 _old_evac_stats.adjust_desired_plab_size();
2548
2549 // Start a new incremental collection set for the mutator phase.
2550 start_new_collection_set();
2551 _allocator->init_mutator_alloc_regions();
2552
2553 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2554 }
2555
2556 void G1CollectedHeap::retire_tlabs() {
2557 ensure_parsability(true);
2558 }
2559
2560 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2561 ResourceMark rm;
2562
2563 IsGCActiveMark active_gc_mark;
2564 GCIdMark gc_id_mark;
2565 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2566
2567 GCTraceCPUTime tcpu(_gc_tracer_stw);
2568
2569 _bytes_used_during_gc = 0;
2570
2571 policy()->decide_on_concurrent_start_pause();
2572 // Record whether this pause may need to trigger a concurrent operation. Later,
2573 // when we signal the G1ConcurrentMarkThread, the collector state has already
2574 // been reset for the next pause.
2575 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2576
2577 // Perform the collection.
2578 G1YoungCollector collector(gc_cause());
2579 collector.collect();
2580
2581 // It should now be safe to tell the concurrent mark thread to start
2582 // without its logging output interfering with the logging output
2583 // that came from the pause.
2584 if (should_start_concurrent_mark_operation) {
2585 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2586 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2587 // thread(s) could be running concurrently with us. Make sure that anything
2588 // after this point does not assume that we are the only GC thread running.
2589 // Note: of course, the actual marking work will not start until the safepoint
2590 // itself is released in SuspendibleThreadSet::desynchronize().
2591 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2592 ConcurrentGCBreakpoints::notify_idle_to_active();
2593 }
2594 }
2595
2596 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2597 uint num_workers = workers()->active_workers();
2598 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2599 workers()->run_task(&unlink_task);
2600 }
2601
2602 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2603 assert(obj != nullptr, "must not be null");
2604 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2605 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2606 // may falsely indicate that this is not the case here: however the collection set only
2607 // contains old regions when concurrent mark is not running.
2608 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2609 }
2610
2611 void G1CollectedHeap::make_pending_list_reachable() {
2612 if (collector_state()->in_concurrent_start_gc()) {
2613 oop pll_head = Universe::reference_pending_list();
2614 if (pll_head != nullptr) {
2615 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2616 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2617 }
2618 }
2619 }
2620
2621 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2622 _num_humongous_objects = num_humongous_total;
2623 _num_humongous_reclaim_candidates = num_humongous_candidates;
2624 }
2625
2626 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2627 const G1CollectionSetCandidates* candidates = collection_set()->candidates();
2628 return !candidates->is_empty();
2629 }
2630
2631 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2632 _collection_set_candidates_card_set_stats = stats;
2633 }
2634
2635 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2636 _young_gen_card_set_stats = stats;
2637 }
2638
2639 void G1CollectedHeap::record_obj_copy_mem_stats() {
2640 policy()->old_gen_alloc_tracker()->
2641 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2642
2643 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2644 create_g1_evac_summary(&_old_evac_stats));
2645 }
2646
2647 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2648 concurrent_mark()->clear_bitmap_for_region(hr);
2649 }
2650
2651 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2652 assert(!hr->is_free(), "the region should not be free");
2653 assert(!hr->is_empty(), "the region should not be empty");
2654 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2655
2656 // Reset region metadata to allow reuse.
2657 hr->hr_clear(true /* clear_space */);
2658 _policy->remset_tracker()->update_at_free(hr);
2659
2660 if (free_list != nullptr) {
2661 free_list->add_ordered(hr);
2662 }
2663 }
2664
2665 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2666 FreeRegionList* free_list) {
2667 assert(hr->is_humongous(), "this is only for humongous regions");
2668 hr->clear_humongous();
2669 free_region(hr, free_list);
2670 }
2671
2672 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2673 const uint humongous_regions_removed) {
2674 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
2675 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2676 _old_set.bulk_remove(old_regions_removed);
2677 _humongous_set.bulk_remove(humongous_regions_removed);
2678 }
2679
2680 }
2681
2682 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2683 assert(list != nullptr, "list can't be null");
2684 if (!list->is_empty()) {
2685 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2686 _hrm.insert_list_into_free_list(list);
2687 }
2688 }
2689
2690 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2691 decrease_used(bytes);
2692 }
2693
2694 void G1CollectedHeap::clear_eden() {
2695 _eden.clear();
2696 }
2697
2698 void G1CollectedHeap::clear_collection_set() {
2699 collection_set()->clear();
2700 }
2701
2702 void G1CollectedHeap::rebuild_free_region_list() {
2703 Ticks start = Ticks::now();
2704 _hrm.rebuild_free_list(workers());
2705 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2706 }
2707
2708 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2709 public:
2710 virtual bool do_heap_region(HeapRegion* r) {
2711 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2712 G1CollectedHeap::heap()->clear_region_attr(r);
2713 r->clear_young_index_in_cset();
2714 return false;
2715 }
2716 };
2717
2718 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2719 G1AbandonCollectionSetClosure cl;
2720 collection_set_iterate_all(&cl);
2721
2722 collection_set->clear();
2723 collection_set->stop_incremental_building();
2724 }
2725
2726 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2727 return _allocator->is_retained_old_region(hr);
2728 }
2729
2730 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2731 _eden.add(hr);
2732 _policy->set_region_eden(hr);
2733 }
2734
2735 #ifdef ASSERT
2736
2737 class NoYoungRegionsClosure: public HeapRegionClosure {
2738 private:
2739 bool _success;
2740 public:
2741 NoYoungRegionsClosure() : _success(true) { }
2742 bool do_heap_region(HeapRegion* r) {
2743 if (r->is_young()) {
2744 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2745 p2i(r->bottom()), p2i(r->end()));
2746 _success = false;
2747 }
2748 return false;
2749 }
2750 bool success() { return _success; }
2751 };
2752
2753 bool G1CollectedHeap::check_young_list_empty() {
2754 bool ret = (young_regions_count() == 0);
2755
2756 NoYoungRegionsClosure closure;
2757 heap_region_iterate(&closure);
2758 ret = ret && closure.success();
2759
2760 return ret;
2761 }
2762
2763 #endif // ASSERT
2764
2765 // Remove the given HeapRegion from the appropriate region set.
2766 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2767 if (hr->is_humongous()) {
2768 _humongous_set.remove(hr);
2769 } else if (hr->is_old()) {
2770 _old_set.remove(hr);
2771 } else if (hr->is_young()) {
2772 // Note that emptying the eden and survivor lists is postponed and instead
2773 // done as the first step when rebuilding the regions sets again. The reason
2774 // for this is that during a full GC string deduplication needs to know if
2775 // a collected region was young or old when the full GC was initiated.
2776 hr->uninstall_surv_rate_group();
2777 } else {
2778 // We ignore free regions, we'll empty the free list afterwards.
2779 assert(hr->is_free(), "it cannot be another type");
2780 }
2781 }
2782
2783 void G1CollectedHeap::increase_used(size_t bytes) {
2784 _summary_bytes_used += bytes;
2785 }
2786
2787 void G1CollectedHeap::decrease_used(size_t bytes) {
2788 assert(_summary_bytes_used >= bytes,
2789 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2790 _summary_bytes_used, bytes);
2791 _summary_bytes_used -= bytes;
2792 }
2793
2794 void G1CollectedHeap::set_used(size_t bytes) {
2795 _summary_bytes_used = bytes;
2796 }
2797
2798 class RebuildRegionSetsClosure : public HeapRegionClosure {
2799 private:
2800 bool _free_list_only;
2801
2802 HeapRegionSet* _old_set;
2803 HeapRegionSet* _humongous_set;
2804
2805 HeapRegionManager* _hrm;
2806
2807 size_t _total_used;
2808
2809 public:
2810 RebuildRegionSetsClosure(bool free_list_only,
2811 HeapRegionSet* old_set,
2812 HeapRegionSet* humongous_set,
2813 HeapRegionManager* hrm) :
2814 _free_list_only(free_list_only), _old_set(old_set),
2815 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2816 assert(_hrm->num_free_regions() == 0, "pre-condition");
2817 if (!free_list_only) {
2818 assert(_old_set->is_empty(), "pre-condition");
2819 assert(_humongous_set->is_empty(), "pre-condition");
2820 }
2821 }
2822
2823 bool do_heap_region(HeapRegion* r) {
2824 if (r->is_empty()) {
2825 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2826 // Add free regions to the free list
2827 r->set_free();
2828 _hrm->insert_into_free_list(r);
2829 } else if (!_free_list_only) {
2830 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2831
2832 if (r->is_humongous()) {
2833 _humongous_set->add(r);
2834 } else {
2835 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2836 // We now move all (non-humongous, non-old) regions to old gen,
2837 // and register them as such.
2838 r->move_to_old();
2839 _old_set->add(r);
2840 }
2841 _total_used += r->used();
2842 }
2843
2844 return false;
2845 }
2846
2847 size_t total_used() {
2848 return _total_used;
2849 }
2850 };
2851
2852 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2853 assert_at_safepoint_on_vm_thread();
2854
2855 if (!free_list_only) {
2856 _eden.clear();
2857 _survivor.clear();
2858 }
2859
2860 RebuildRegionSetsClosure cl(free_list_only,
2861 &_old_set, &_humongous_set,
2862 &_hrm);
2863 heap_region_iterate(&cl);
2864
2865 if (!free_list_only) {
2866 set_used(cl.total_used());
2867 }
2868 assert_used_and_recalculate_used_equal(this);
2869 }
2870
2871 // Methods for the mutator alloc region
2872
2873 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2874 bool force,
2875 uint node_index) {
2876 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2877 bool should_allocate = policy()->should_allocate_mutator_region();
2878 if (force || should_allocate) {
2879 HeapRegion* new_alloc_region = new_region(word_size,
2880 HeapRegionType::Eden,
2881 false /* do_expand */,
2882 node_index);
2883 if (new_alloc_region != nullptr) {
2884 set_region_short_lived_locked(new_alloc_region);
2885 _hr_printer.alloc(new_alloc_region, !should_allocate);
2886 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2887 return new_alloc_region;
2888 }
2889 }
2890 return nullptr;
2891 }
2892
2893 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
2894 size_t allocated_bytes) {
2895 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2896 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
2897
2898 collection_set()->add_eden_region(alloc_region);
2899 increase_used(allocated_bytes);
2900 _eden.add_used_bytes(allocated_bytes);
2901 _hr_printer.retire(alloc_region);
2902
2903 // We update the eden sizes here, when the region is retired,
2904 // instead of when it's allocated, since this is the point that its
2905 // used space has been recorded in _summary_bytes_used.
2906 monitoring_support()->update_eden_size();
2907 }
2908
2909 // Methods for the GC alloc regions
2910
2911 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
2912 if (dest.is_old()) {
2913 return true;
2914 } else {
2915 return survivor_regions_count() < policy()->max_survivor_regions();
2916 }
2917 }
2918
2919 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
2920 assert(FreeList_lock->owned_by_self(), "pre-condition");
2921
2922 if (!has_more_regions(dest)) {
2923 return nullptr;
2924 }
2925
2926 HeapRegionType type;
2927 if (dest.is_young()) {
2928 type = HeapRegionType::Survivor;
2929 } else {
2930 type = HeapRegionType::Old;
2931 }
2932
2933 HeapRegion* new_alloc_region = new_region(word_size,
2934 type,
2935 true /* do_expand */,
2936 node_index);
2937
2938 if (new_alloc_region != nullptr) {
2939 if (type.is_survivor()) {
2940 new_alloc_region->set_survivor();
2941 _survivor.add(new_alloc_region);
2942 register_new_survivor_region_with_region_attr(new_alloc_region);
2943 } else {
2944 new_alloc_region->set_old();
2945 }
2946 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2947 register_region_with_region_attr(new_alloc_region);
2948 _hr_printer.alloc(new_alloc_region);
2949 return new_alloc_region;
2950 }
2951 return nullptr;
2952 }
2953
2954 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
2955 size_t allocated_bytes,
2956 G1HeapRegionAttr dest) {
2957 _bytes_used_during_gc += allocated_bytes;
2958 if (dest.is_old()) {
2959 old_set_add(alloc_region);
2960 } else {
2961 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
2962 _survivor.add_used_bytes(allocated_bytes);
2963 }
2964
2965 bool const during_im = collector_state()->in_concurrent_start_gc();
2966 if (during_im && allocated_bytes > 0) {
2967 _cm->add_root_region(alloc_region);
2968 }
2969 _hr_printer.retire(alloc_region);
2970 }
2971
2972 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
2973 bool expanded = false;
2974 uint index = _hrm.find_highest_free(&expanded);
2975
2976 if (index != G1_NO_HRM_INDEX) {
2977 if (expanded) {
2978 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
2979 HeapRegion::GrainWords * HeapWordSize);
2980 }
2981 return _hrm.allocate_free_regions_starting_at(index, 1);
2982 }
2983 return nullptr;
2984 }
2985
2986 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
2987 assert(!_cm->is_marked_in_bitmap(obj), "must be");
2988
2989 _cm->raw_mark_in_bitmap(obj);
2990 if (collector_state()->in_concurrent_start_gc()) {
2991 _cm->add_to_liveness(worker_id, obj, obj_size);
2992 }
2993 }
2994
2995 // Optimized nmethod scanning
2996 class RegisterNMethodOopClosure: public OopClosure {
2997 G1CollectedHeap* _g1h;
2998 nmethod* _nm;
2999
3000 public:
3001 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3002 _g1h(g1h), _nm(nm) {}
3003
3004 void do_oop(oop* p) {
3005 oop heap_oop = RawAccess<>::oop_load(p);
3006 if (!CompressedOops::is_null(heap_oop)) {
3007 oop obj = CompressedOops::decode_not_null(heap_oop);
3008 HeapRegion* hr = _g1h->heap_region_containing(obj);
3009 assert(!hr->is_continues_humongous(),
3010 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3011 " starting at " HR_FORMAT,
3012 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3013
3014 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3015 hr->add_code_root_locked(_nm);
3016 }
3017 }
3018
3019 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3020 };
3021
3022 class UnregisterNMethodOopClosure: public OopClosure {
3023 G1CollectedHeap* _g1h;
3024 nmethod* _nm;
3025
3026 public:
3027 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3028 _g1h(g1h), _nm(nm) {}
3029
3030 void do_oop(oop* p) {
3031 oop heap_oop = RawAccess<>::oop_load(p);
3032 if (!CompressedOops::is_null(heap_oop)) {
3033 oop obj = CompressedOops::decode_not_null(heap_oop);
3034 HeapRegion* hr = _g1h->heap_region_containing(obj);
3035 assert(!hr->is_continues_humongous(),
3036 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3037 " starting at " HR_FORMAT,
3038 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3039
3040 hr->remove_code_root(_nm);
3041 }
3042 }
3043
3044 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3045 };
3046
3047 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3048 guarantee(nm != nullptr, "sanity");
3049 RegisterNMethodOopClosure reg_cl(this, nm);
3050 nm->oops_do(®_cl);
3051 }
3052
3053 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3054 guarantee(nm != nullptr, "sanity");
3055 UnregisterNMethodOopClosure reg_cl(this, nm);
3056 nm->oops_do(®_cl, true);
3057 }
3058
3059 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3060 if (evacuation_failed) {
3061 // Reset the G1EvacuationFailureALot counters and flags
3062 evac_failure_injector()->reset();
3063
3064 set_used(recalculate_used());
3065 } else {
3066 // The "used" of the collection set have already been subtracted
3067 // when they were freed. Add in the bytes used.
3068 increase_used(_bytes_used_during_gc);
3069 }
3070 }
3071
3072 class RebuildCodeRootClosure: public CodeBlobClosure {
3073 G1CollectedHeap* _g1h;
3074
3075 public:
3076 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3077 _g1h(g1h) {}
3078
3079 void do_code_blob(CodeBlob* cb) {
3080 nmethod* nm = cb->as_nmethod_or_null();
3081 if (nm != nullptr) {
3082 _g1h->register_nmethod(nm);
3083 }
3084 }
3085 };
3086
3087 void G1CollectedHeap::rebuild_code_roots() {
3088 RebuildCodeRootClosure blob_cl(this);
3089 CodeCache::blobs_do(&blob_cl);
3090 }
3091
3092 void G1CollectedHeap::initialize_serviceability() {
3093 _monitoring_support->initialize_serviceability();
3094 }
3095
3096 MemoryUsage G1CollectedHeap::memory_usage() {
3097 return _monitoring_support->memory_usage();
3098 }
3099
3100 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3101 return _monitoring_support->memory_managers();
3102 }
3103
3104 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3105 return _monitoring_support->memory_pools();
3106 }
3107
3108 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3109 HeapRegion* region = heap_region_containing(start);
3110 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3111 }
3112
3113 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3114 // We can reach here with an active code cache marking cycle either because the
3115 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3116 // concurrent start young collection was below the threshold) or aborted. See
3117 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3118 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3119 // still have to arm all nmethod entry barriers. They are needed for adding oop
3120 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3121 if (!CodeCache::is_gc_marking_cycle_active()) {
3122 CodeCache::on_gc_marking_cycle_start();
3123 }
3124 if (concurrent_mark_start) {
3125 CodeCache::arm_all_nmethods();
3126 }
3127 }
3128
3129 void G1CollectedHeap::finish_codecache_marking_cycle() {
3130 CodeCache::on_gc_marking_cycle_finish();
3131 CodeCache::arm_all_nmethods();
3132 }