1 /*
2 * Copyright (c) 2001, 2024, 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/systemDictionary.hpp"
29 #include "code/codeCache.hpp"
30 #include "compiler/oopMap.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1BatchedTask.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectionSetCandidates.hpp"
38 #include "gc/g1/g1CollectorState.hpp"
39 #include "gc/g1/g1ConcurrentRefine.hpp"
40 #include "gc/g1/g1ConcurrentRefineThread.hpp"
41 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
42 #include "gc/g1/g1DirtyCardQueue.hpp"
43 #include "gc/g1/g1EvacStats.inline.hpp"
44 #include "gc/g1/g1FullCollector.hpp"
45 #include "gc/g1/g1GCCounters.hpp"
46 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
47 #include "gc/g1/g1GCPhaseTimes.hpp"
48 #include "gc/g1/g1GCPauseType.hpp"
49 #include "gc/g1/g1HeapRegion.inline.hpp"
50 #include "gc/g1/g1HeapRegionRemSet.inline.hpp"
51 #include "gc/g1/g1HeapRegionSet.inline.hpp"
52 #include "gc/g1/g1HeapSizingPolicy.hpp"
53 #include "gc/g1/g1HeapTransition.hpp"
54 #include "gc/g1/g1HeapVerifier.hpp"
55 #include "gc/g1/g1InitLogger.hpp"
56 #include "gc/g1/g1MemoryPool.hpp"
57 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp"
58 #include "gc/g1/g1OopClosures.inline.hpp"
59 #include "gc/g1/g1ParallelCleaning.hpp"
60 #include "gc/g1/g1ParScanThreadState.inline.hpp"
61 #include "gc/g1/g1PeriodicGCTask.hpp"
62 #include "gc/g1/g1Policy.hpp"
63 #include "gc/g1/g1RedirtyCardsQueue.hpp"
64 #include "gc/g1/g1RegionPinCache.inline.hpp"
65 #include "gc/g1/g1RegionToSpaceMapper.hpp"
66 #include "gc/g1/g1RemSet.hpp"
67 #include "gc/g1/g1RootClosures.hpp"
68 #include "gc/g1/g1RootProcessor.hpp"
69 #include "gc/g1/g1SATBMarkQueueSet.hpp"
70 #include "gc/g1/g1ServiceThread.hpp"
71 #include "gc/g1/g1ThreadLocalData.hpp"
72 #include "gc/g1/g1Trace.hpp"
73 #include "gc/g1/g1UncommitRegionTask.hpp"
74 #include "gc/g1/g1VMOperations.hpp"
75 #include "gc/g1/g1YoungCollector.hpp"
76 #include "gc/g1/g1YoungGCAllocationFailureInjector.hpp"
77 #include "gc/shared/classUnloadingContext.hpp"
78 #include "gc/shared/concurrentGCBreakpoints.hpp"
79 #include "gc/shared/gcBehaviours.hpp"
80 #include "gc/shared/gcHeapSummary.hpp"
81 #include "gc/shared/gcId.hpp"
82 #include "gc/shared/gcTimer.hpp"
83 #include "gc/shared/gcTraceTime.inline.hpp"
84 #include "gc/shared/isGCActiveMark.hpp"
85 #include "gc/shared/locationPrinter.inline.hpp"
86 #include "gc/shared/oopStorageParState.hpp"
87 #include "gc/shared/preservedMarks.inline.hpp"
88 #include "gc/shared/referenceProcessor.inline.hpp"
89 #include "gc/shared/suspendibleThreadSet.hpp"
90 #include "gc/shared/taskqueue.inline.hpp"
91 #include "gc/shared/taskTerminator.hpp"
92 #include "gc/shared/tlab_globals.hpp"
93 #include "gc/shared/workerPolicy.hpp"
94 #include "gc/shared/weakProcessor.inline.hpp"
95 #include "logging/log.hpp"
96 #include "memory/allocation.hpp"
97 #include "memory/heapInspection.hpp"
98 #include "memory/iterator.hpp"
99 #include "memory/metaspaceUtils.hpp"
100 #include "memory/resourceArea.hpp"
101 #include "memory/universe.hpp"
102 #include "oops/access.inline.hpp"
103 #include "oops/compressedOops.inline.hpp"
104 #include "oops/oop.inline.hpp"
105 #include "runtime/atomic.hpp"
106 #include "runtime/cpuTimeCounters.hpp"
107 #include "runtime/handles.inline.hpp"
108 #include "runtime/init.hpp"
109 #include "runtime/java.hpp"
110 #include "runtime/orderAccess.hpp"
111 #include "runtime/threadSMR.hpp"
112 #include "runtime/vmThread.hpp"
113 #include "utilities/align.hpp"
114 #include "utilities/autoRestore.hpp"
115 #include "utilities/bitMap.inline.hpp"
116 #include "utilities/globalDefinitions.hpp"
117 #include "utilities/stack.inline.hpp"
118
119 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
120
121 // INVARIANTS/NOTES
122 //
123 // All allocation activity covered by the G1CollectedHeap interface is
124 // serialized by acquiring the HeapLock. This happens in mem_allocate
125 // and allocate_new_tlab, which are the "entry" points to the
126 // allocation code from the rest of the JVM. (Note that this does not
127 // apply to TLAB allocation, which is not part of this interface: it
128 // is done by clients of this interface.)
129
130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
132 }
133
134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
135 // The from card cache is not the memory that is actually committed. So we cannot
136 // take advantage of the zero_filled parameter.
137 reset_from_card_cache(start_idx, num_regions);
138 }
139
140 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
141 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
142 cl->set_max_workers(num_workers);
143 workers()->run_task(cl, num_workers);
144 }
145
146 uint G1CollectedHeap::get_chunks_per_region() {
147 uint log_region_size = HeapRegion::LogOfHRGrainBytes;
148 // Limit the expected input values to current known possible values of the
149 // (log) region size. Adjust as necessary after testing if changing the permissible
150 // values for region size.
151 assert(log_region_size >= 20 && log_region_size <= 29,
152 "expected value in [20,29], but got %u", log_region_size);
153 return 1u << (log_region_size / 2 - 4);
154 }
155
156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
157 MemRegion mr) {
158 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
159 }
160
161 // Private methods.
162
163 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
164 HeapRegionType type,
165 bool do_expand,
166 uint node_index) {
167 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
168 "the only time we use this to allocate a humongous region is "
169 "when we are allocating a single humongous region");
170
171 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
172
173 if (res == nullptr && do_expand) {
174 // Currently, only attempts to allocate GC alloc regions set
175 // do_expand to true. So, we should only reach here during a
176 // safepoint.
177 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
178
179 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
180 word_size * HeapWordSize);
181
182 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
183 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
184 word_size * HeapWordSize);
185 if (expand_single_region(node_index)) {
186 // Given that expand_single_region() succeeded in expanding the heap, and we
187 // always expand the heap by an amount aligned to the heap
188 // region size, the free list should in theory not be empty.
189 // In either case allocate_free_region() will check for null.
190 res = _hrm.allocate_free_region(type, node_index);
191 }
192 }
193 return res;
194 }
195
196 void G1CollectedHeap::set_humongous_metadata(HeapRegion* first_hr,
197 uint num_regions,
198 size_t word_size,
199 bool update_remsets) {
200 // Calculate the new top of the humongous object.
201 HeapWord* obj_top = first_hr->bottom() + word_size;
202 // The word size sum of all the regions used
203 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
204 assert(word_size <= word_size_sum, "sanity");
205
206 // How many words memory we "waste" which cannot hold a filler object.
207 size_t words_not_fillable = 0;
208
209 // Pad out the unused tail of the last region with filler
210 // objects, for improved usage accounting.
211
212 // How many words can we use for filler objects.
213 size_t words_fillable = word_size_sum - word_size;
214
215 if (words_fillable >= G1CollectedHeap::min_fill_size()) {
216 G1CollectedHeap::fill_with_objects(obj_top, words_fillable);
217 } else {
218 // We have space to fill, but we cannot fit an object there.
219 words_not_fillable = words_fillable;
220 words_fillable = 0;
221 }
222
223 // We will set up the first region as "starts humongous". This
224 // will also update the BOT covering all the regions to reflect
225 // that there is a single object that starts at the bottom of the
226 // first region.
227 first_hr->hr_clear(false /* clear_space */);
228 first_hr->set_starts_humongous(obj_top, words_fillable);
229
230 if (update_remsets) {
231 _policy->remset_tracker()->update_at_allocate(first_hr);
232 }
233
234 // Indices of first and last regions in the series.
235 uint first = first_hr->hrm_index();
236 uint last = first + num_regions - 1;
237
238 HeapRegion* hr = nullptr;
239 for (uint i = first + 1; i <= last; ++i) {
240 hr = region_at(i);
241 hr->hr_clear(false /* clear_space */);
242 hr->set_continues_humongous(first_hr);
243 if (update_remsets) {
244 _policy->remset_tracker()->update_at_allocate(hr);
245 }
246 }
247
248 // Up to this point no concurrent thread would have been able to
249 // do any scanning on any region in this series. All the top
250 // fields still point to bottom, so the intersection between
251 // [bottom,top] and [card_start,card_end] will be empty. Before we
252 // update the top fields, we'll do a storestore to make sure that
253 // no thread sees the update to top before the zeroing of the
254 // object header and the BOT initialization.
255 OrderAccess::storestore();
256
257 // Now, we will update the top fields of the "continues humongous"
258 // regions except the last one.
259 for (uint i = first; i < last; ++i) {
260 hr = region_at(i);
261 hr->set_top(hr->end());
262 }
263
264 hr = region_at(last);
265 // If we cannot fit a filler object, we must set top to the end
266 // of the humongous object, otherwise we cannot iterate the heap
267 // and the BOT will not be complete.
268 hr->set_top(hr->end() - words_not_fillable);
269
270 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
271 "obj_top should be in last region");
272
273 assert(words_not_fillable == 0 ||
274 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
275 "Miscalculation in humongous allocation");
276 }
277
278 HeapWord*
279 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
280 uint num_regions,
281 size_t word_size) {
282 assert(first_hr != nullptr, "pre-condition");
283 assert(is_humongous(word_size), "word_size should be humongous");
284 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
285
286 // Index of last region in the series.
287 uint first = first_hr->hrm_index();
288 uint last = first + num_regions - 1;
289
290 // We need to initialize the region(s) we just discovered. This is
291 // a bit tricky given that it can happen concurrently with
292 // refinement threads refining cards on these regions and
293 // potentially wanting to refine the BOT as they are scanning
294 // those cards (this can happen shortly after a cleanup; see CR
295 // 6991377). So we have to set up the region(s) carefully and in
296 // a specific order.
297
298 // The passed in hr will be the "starts humongous" region. The header
299 // of the new object will be placed at the bottom of this region.
300 HeapWord* new_obj = first_hr->bottom();
301
302 // First, we need to zero the header of the space that we will be
303 // allocating. When we update top further down, some refinement
304 // threads might try to scan the region. By zeroing the header we
305 // ensure that any thread that will try to scan the region will
306 // come across the zero klass word and bail out.
307 //
308 // NOTE: It would not have been correct to have used
309 // CollectedHeap::fill_with_object() and make the space look like
310 // an int array. The thread that is doing the allocation will
311 // later update the object header to a potentially different array
312 // type and, for a very short period of time, the klass and length
313 // fields will be inconsistent. This could cause a refinement
314 // thread to calculate the object size incorrectly.
315 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
316
317 // Next, update the metadata for the regions.
318 set_humongous_metadata(first_hr, num_regions, word_size, true);
319
320 HeapRegion* last_hr = region_at(last);
321 size_t used = byte_size(first_hr->bottom(), last_hr->top());
322
323 increase_used(used);
324
325 for (uint i = first; i <= last; ++i) {
326 HeapRegion *hr = region_at(i);
327 _humongous_set.add(hr);
328 _hr_printer.alloc(hr);
329 }
330
331 return new_obj;
332 }
333
334 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
335 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
336 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
337 }
338
339 // If could fit into free regions w/o expansion, try.
340 // Otherwise, if can expand, do so.
341 // Otherwise, if using ex regions might help, try with ex given back.
342 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
343 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
344
345 _verifier->verify_region_sets_optional();
346
347 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
348
349 // Policy: First try to allocate a humongous object in the free list.
350 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
351 if (humongous_start == nullptr) {
352 // Policy: We could not find enough regions for the humongous object in the
353 // free list. Look through the heap to find a mix of free and uncommitted regions.
354 // If so, expand the heap and allocate the humongous object.
355 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
356 if (humongous_start != nullptr) {
357 // We managed to find a region by expanding the heap.
358 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
359 word_size * HeapWordSize);
360 policy()->record_new_heap_size(num_regions());
361 } else {
362 // Policy: Potentially trigger a defragmentation GC.
363 }
364 }
365
366 HeapWord* result = nullptr;
367 if (humongous_start != nullptr) {
368 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
369 assert(result != nullptr, "it should always return a valid result");
370
371 // A successful humongous object allocation changes the used space
372 // information of the old generation so we need to recalculate the
373 // sizes and update the jstat counters here.
374 monitoring_support()->update_sizes();
375 }
376
377 _verifier->verify_region_sets_optional();
378
379 return result;
380 }
381
382 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
383 size_t requested_size,
384 size_t* actual_size) {
385 assert_heap_not_locked_and_not_at_safepoint();
386 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
387
388 return attempt_allocation(min_size, requested_size, actual_size);
389 }
390
391 HeapWord*
392 G1CollectedHeap::mem_allocate(size_t word_size,
393 bool* gc_overhead_limit_was_exceeded) {
394 assert_heap_not_locked_and_not_at_safepoint();
395
396 if (is_humongous(word_size)) {
397 return attempt_allocation_humongous(word_size);
398 }
399 size_t dummy = 0;
400 return attempt_allocation(word_size, word_size, &dummy);
401 }
402
403 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
404 ResourceMark rm; // For retrieving the thread names in log messages.
405
406 // Make sure you read the note in attempt_allocation_humongous().
407
408 assert_heap_not_locked_and_not_at_safepoint();
409 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
410 "be called for humongous allocation requests");
411
412 // We should only get here after the first-level allocation attempt
413 // (attempt_allocation()) failed to allocate.
414
415 // We will loop until a) we manage to successfully perform the allocation or b)
416 // successfully schedule a collection which fails to perform the allocation.
417 // Case b) is the only case when we'll return null.
418 HeapWord* result = nullptr;
419 for (uint try_count = 1; /* we'll return */; try_count++) {
420 uint gc_count_before;
421
422 {
423 MutexLocker x(Heap_lock);
424
425 // Now that we have the lock, we first retry the allocation in case another
426 // thread changed the region while we were waiting to acquire the lock.
427 result = _allocator->attempt_allocation_locked(word_size);
428 if (result != nullptr) {
429 return result;
430 }
431
432 // Read the GC count while still holding the Heap_lock.
433 gc_count_before = total_collections();
434 }
435
436 bool succeeded;
437 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
438 if (succeeded) {
439 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
440 Thread::current()->name(), p2i(result));
441 return result;
442 }
443
444 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
445 Thread::current()->name(), word_size);
446
447 // We can reach here if we were unsuccessful in scheduling a collection (because
448 // another thread beat us to it). In this case immeditealy retry the allocation
449 // attempt because another thread successfully performed a collection and possibly
450 // reclaimed enough space. The first attempt (without holding the Heap_lock) is
451 // here and the follow-on attempt will be at the start of the next loop
452 // iteration (after taking the Heap_lock).
453 size_t dummy = 0;
454 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
455 if (result != nullptr) {
456 return result;
457 }
458
459 // Give a warning if we seem to be looping forever.
460 if ((QueuedAllocationWarningCount > 0) &&
461 (try_count % QueuedAllocationWarningCount == 0)) {
462 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
463 Thread::current()->name(), try_count, word_size);
464 }
465 }
466
467 ShouldNotReachHere();
468 return nullptr;
469 }
470
471 template <typename Func>
472 void G1CollectedHeap::iterate_regions_in_range(MemRegion range, const Func& func) {
473 // Mark each G1 region touched by the range as old, add it to
474 // the old set, and set top.
475 HeapRegion* curr_region = _hrm.addr_to_region(range.start());
476 HeapRegion* end_region = _hrm.addr_to_region(range.last());
477
478 while (curr_region != nullptr) {
479 bool is_last = curr_region == end_region;
480 HeapRegion* next_region = is_last ? nullptr : _hrm.next_region_in_heap(curr_region);
481
482 func(curr_region, is_last);
483
484 curr_region = next_region;
485 }
486 }
487
488 HeapWord* G1CollectedHeap::alloc_archive_region(size_t word_size, HeapWord* preferred_addr) {
489 assert(!is_init_completed(), "Expect to be called at JVM init time");
490 MutexLocker x(Heap_lock);
491
492 MemRegion reserved = _hrm.reserved();
493
494 if (reserved.word_size() <= word_size) {
495 log_info(gc, heap)("Unable to allocate regions as archive heap is too large; size requested = " SIZE_FORMAT
496 " bytes, heap = " SIZE_FORMAT " bytes", word_size, reserved.word_size());
497 return nullptr;
498 }
499
500 // Temporarily disable pretouching of heap pages. This interface is used
501 // when mmap'ing archived heap data in, so pre-touching is wasted.
502 FlagSetting fs(AlwaysPreTouch, false);
503
504 size_t commits = 0;
505 // Attempt to allocate towards the end of the heap.
506 HeapWord* start_addr = reserved.end() - align_up(word_size, HeapRegion::GrainWords);
507 MemRegion range = MemRegion(start_addr, word_size);
508 HeapWord* last_address = range.last();
509 if (!_hrm.allocate_containing_regions(range, &commits, workers())) {
510 return nullptr;
511 }
512 increase_used(word_size * HeapWordSize);
513 if (commits != 0) {
514 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
515 HeapRegion::GrainWords * HeapWordSize * commits);
516 }
517
518 // Mark each G1 region touched by the range as old, add it to
519 // the old set, and set top.
520 auto set_region_to_old = [&] (HeapRegion* r, bool is_last) {
521 assert(r->is_empty(), "Region already in use (%u)", r->hrm_index());
522
523 HeapWord* top = is_last ? last_address + 1 : r->end();
524 r->set_top(top);
525
526 r->set_old();
527 _hr_printer.alloc(r);
528 _old_set.add(r);
529 };
530
531 iterate_regions_in_range(range, set_region_to_old);
532 return start_addr;
533 }
534
535 void G1CollectedHeap::populate_archive_regions_bot(MemRegion range) {
536 assert(!is_init_completed(), "Expect to be called at JVM init time");
537
538 iterate_regions_in_range(range,
539 [&] (HeapRegion* r, bool is_last) {
540 r->update_bot();
541 });
542 }
543
544 void G1CollectedHeap::dealloc_archive_regions(MemRegion range) {
545 assert(!is_init_completed(), "Expect to be called at JVM init time");
546 MemRegion reserved = _hrm.reserved();
547 size_t size_used = 0;
548 uint shrink_count = 0;
549
550 // Free the G1 regions that are within the specified range.
551 MutexLocker x(Heap_lock);
552 HeapWord* start_address = range.start();
553 HeapWord* last_address = range.last();
554
555 assert(reserved.contains(start_address) && reserved.contains(last_address),
556 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
557 p2i(start_address), p2i(last_address));
558 size_used += range.byte_size();
559
560 // Free, empty and uncommit regions with CDS archive content.
561 auto dealloc_archive_region = [&] (HeapRegion* r, bool is_last) {
562 guarantee(r->is_old(), "Expected old region at index %u", r->hrm_index());
563 _old_set.remove(r);
564 r->set_free();
565 r->set_top(r->bottom());
566 _hrm.shrink_at(r->hrm_index(), 1);
567 shrink_count++;
568 };
569
570 iterate_regions_in_range(range, dealloc_archive_region);
571
572 if (shrink_count != 0) {
573 log_debug(gc, ergo, heap)("Attempt heap shrinking (CDS archive regions). Total size: " SIZE_FORMAT "B",
574 HeapRegion::GrainWords * HeapWordSize * shrink_count);
575 // Explicit uncommit.
576 uncommit_regions(shrink_count);
577 }
578 decrease_used(size_used);
579 }
580
581 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
582 size_t desired_word_size,
583 size_t* actual_word_size) {
584 assert_heap_not_locked_and_not_at_safepoint();
585 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
586 "be called for humongous allocation requests");
587
588 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
589
590 if (result == nullptr) {
591 *actual_word_size = desired_word_size;
592 result = attempt_allocation_slow(desired_word_size);
593 }
594
595 assert_heap_not_locked();
596 if (result != nullptr) {
597 assert(*actual_word_size != 0, "Actual size must have been set here");
598 dirty_young_block(result, *actual_word_size);
599 } else {
600 *actual_word_size = 0;
601 }
602
603 return result;
604 }
605
606 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
607 ResourceMark rm; // For retrieving the thread names in log messages.
608
609 // The structure of this method has a lot of similarities to
610 // attempt_allocation_slow(). The reason these two were not merged
611 // into a single one is that such a method would require several "if
612 // allocation is not humongous do this, otherwise do that"
613 // conditional paths which would obscure its flow. In fact, an early
614 // version of this code did use a unified method which was harder to
615 // follow and, as a result, it had subtle bugs that were hard to
616 // track down. So keeping these two methods separate allows each to
617 // be more readable. It will be good to keep these two in sync as
618 // much as possible.
619
620 assert_heap_not_locked_and_not_at_safepoint();
621 assert(is_humongous(word_size), "attempt_allocation_humongous() "
622 "should only be called for humongous allocations");
623
624 // Humongous objects can exhaust the heap quickly, so we should check if we
625 // need to start a marking cycle at each humongous object allocation. We do
626 // the check before we do the actual allocation. The reason for doing it
627 // before the allocation is that we avoid having to keep track of the newly
628 // allocated memory while we do a GC.
629 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
630 word_size)) {
631 collect(GCCause::_g1_humongous_allocation);
632 }
633
634 // We will loop until a) we manage to successfully perform the allocation or b)
635 // successfully schedule a collection which fails to perform the allocation.
636 // Case b) is the only case when we'll return null.
637 HeapWord* result = nullptr;
638 for (uint try_count = 1; /* we'll return */; try_count++) {
639 uint gc_count_before;
640
641
642 {
643 MutexLocker x(Heap_lock);
644
645 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
646 // Given that humongous objects are not allocated in young
647 // regions, we'll first try to do the allocation without doing a
648 // collection hoping that there's enough space in the heap.
649 result = humongous_obj_allocate(word_size);
650 if (result != nullptr) {
651 policy()->old_gen_alloc_tracker()->
652 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
653 return result;
654 }
655
656 // Read the GC count while still holding the Heap_lock.
657 gc_count_before = total_collections();
658 }
659
660 bool succeeded;
661 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
662 if (succeeded) {
663 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
664 Thread::current()->name(), p2i(result));
665 if (result != nullptr) {
666 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
667 policy()->old_gen_alloc_tracker()->
668 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
669 }
670 return result;
671 }
672
673 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
674 Thread::current()->name(), word_size);
675
676 // We can reach here if we were unsuccessful in scheduling a collection (because
677 // another thread beat us to it).
678 // Humongous object allocation always needs a lock, so we wait for the retry
679 // in the next iteration of the loop, unlike for the regular iteration case.
680 // Give a warning if we seem to be looping forever.
681
682 if ((QueuedAllocationWarningCount > 0) &&
683 (try_count % QueuedAllocationWarningCount == 0)) {
684 log_warning(gc, alloc)("%s: Retried allocation %u times for %zu words",
685 Thread::current()->name(), try_count, word_size);
686 }
687 }
688
689 ShouldNotReachHere();
690 return nullptr;
691 }
692
693 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
694 bool expect_null_mutator_alloc_region) {
695 assert_at_safepoint_on_vm_thread();
696 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
697 "the current alloc region was unexpectedly found to be non-null");
698
699 if (!is_humongous(word_size)) {
700 return _allocator->attempt_allocation_locked(word_size);
701 } else {
702 HeapWord* result = humongous_obj_allocate(word_size);
703 if (result != nullptr && policy()->need_to_start_conc_mark("STW humongous allocation")) {
704 collector_state()->set_initiate_conc_mark_if_possible(true);
705 }
706 return result;
707 }
708
709 ShouldNotReachHere();
710 }
711
712 class PostCompactionPrinterClosure: public HeapRegionClosure {
713 private:
714 G1HRPrinter* _hr_printer;
715 public:
716 bool do_heap_region(HeapRegion* hr) {
717 assert(!hr->is_young(), "not expecting to find young regions");
718 _hr_printer->post_compaction(hr);
719 return false;
720 }
721
722 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
723 : _hr_printer(hr_printer) { }
724 };
725
726 void G1CollectedHeap::print_heap_after_full_collection() {
727 // Post collection region logging.
728 // We should do this after we potentially resize the heap so
729 // that all the COMMIT / UNCOMMIT events are generated before
730 // the compaction events.
731 if (_hr_printer.is_active()) {
732 PostCompactionPrinterClosure cl(hr_printer());
733 heap_region_iterate(&cl);
734 }
735 }
736
737 bool G1CollectedHeap::abort_concurrent_cycle() {
738 // Disable discovery and empty the discovered lists
739 // for the CM ref processor.
740 _ref_processor_cm->disable_discovery();
741 _ref_processor_cm->abandon_partial_discovery();
742 _ref_processor_cm->verify_no_references_recorded();
743
744 // Abandon current iterations of concurrent marking and concurrent
745 // refinement, if any are in progress.
746 return concurrent_mark()->concurrent_cycle_abort();
747 }
748
749 void G1CollectedHeap::prepare_heap_for_full_collection() {
750 // Make sure we'll choose a new allocation region afterwards.
751 _allocator->release_mutator_alloc_regions();
752 _allocator->abandon_gc_alloc_regions();
753
754 // We may have added regions to the current incremental collection
755 // set between the last GC or pause and now. We need to clear the
756 // incremental collection set and then start rebuilding it afresh
757 // after this full GC.
758 abandon_collection_set(collection_set());
759
760 _hrm.remove_all_free_regions();
761 }
762
763 void G1CollectedHeap::verify_before_full_collection() {
764 assert_used_and_recalculate_used_equal(this);
765 if (!VerifyBeforeGC) {
766 return;
767 }
768 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
769 return;
770 }
771 _verifier->verify_region_sets_optional();
772 _verifier->verify_before_gc();
773 _verifier->verify_bitmap_clear(true /* above_tams_only */);
774 }
775
776 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
777 // Prepare heap for normal collections.
778 assert(num_free_regions() == 0, "we should not have added any free regions");
779 rebuild_region_sets(false /* free_list_only */);
780 abort_refinement();
781 resize_heap_if_necessary();
782 uncommit_regions_if_necessary();
783
784 // Rebuild the code root lists for each region
785 rebuild_code_roots();
786
787 start_new_collection_set();
788 _allocator->init_mutator_alloc_regions();
789
790 // Post collection state updates.
791 MetaspaceGC::compute_new_size();
792 }
793
794 void G1CollectedHeap::abort_refinement() {
795 // Discard all remembered set updates and reset refinement statistics.
796 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
797 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
798 "DCQS should be empty");
799 concurrent_refine()->get_and_reset_refinement_stats();
800 }
801
802 void G1CollectedHeap::verify_after_full_collection() {
803 if (!VerifyAfterGC) {
804 return;
805 }
806 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
807 return;
808 }
809 _hrm.verify_optional();
810 _verifier->verify_region_sets_optional();
811 _verifier->verify_after_gc();
812 _verifier->verify_bitmap_clear(false /* above_tams_only */);
813
814 // At this point there should be no regions in the
815 // entire heap tagged as young.
816 assert(check_young_list_empty(), "young list should be empty at this point");
817
818 // Note: since we've just done a full GC, concurrent
819 // marking is no longer active. Therefore we need not
820 // re-enable reference discovery for the CM ref processor.
821 // That will be done at the start of the next marking cycle.
822 // We also know that the STW processor should no longer
823 // discover any new references.
824 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
825 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
826 _ref_processor_stw->verify_no_references_recorded();
827 _ref_processor_cm->verify_no_references_recorded();
828 }
829
830 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs,
831 bool do_maximal_compaction) {
832 assert_at_safepoint_on_vm_thread();
833
834 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
835 soft_ref_policy()->should_clear_all_soft_refs();
836
837 G1FullGCMark gc_mark;
838 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true);
839 G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
840
841 collector.prepare_collection();
842 collector.collect();
843 collector.complete_collection();
844
845 // Full collection was successfully completed.
846 return true;
847 }
848
849 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
850 // Currently, there is no facility in the do_full_collection(bool) API to notify
851 // the caller that the collection did not succeed (e.g., because it was locked
852 // out by the GC locker). So, right now, we'll ignore the return value.
853
854 do_full_collection(clear_all_soft_refs,
855 false /* do_maximal_compaction */);
856 }
857
858 bool G1CollectedHeap::upgrade_to_full_collection() {
859 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
860 log_info(gc, ergo)("Attempting full compaction clearing soft references");
861 bool success = do_full_collection(true /* clear_all_soft_refs */,
862 false /* do_maximal_compaction */);
863 // do_full_collection only fails if blocked by GC locker and that can't
864 // be the case here since we only call this when already completed one gc.
865 assert(success, "invariant");
866 return success;
867 }
868
869 void G1CollectedHeap::resize_heap_if_necessary() {
870 assert_at_safepoint_on_vm_thread();
871
872 bool should_expand;
873 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
874
875 if (resize_amount == 0) {
876 return;
877 } else if (should_expand) {
878 expand(resize_amount, _workers);
879 } else {
880 shrink(resize_amount);
881 }
882 }
883
884 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
885 bool do_gc,
886 bool maximal_compaction,
887 bool expect_null_mutator_alloc_region,
888 bool* gc_succeeded) {
889 *gc_succeeded = true;
890 // Let's attempt the allocation first.
891 HeapWord* result =
892 attempt_allocation_at_safepoint(word_size,
893 expect_null_mutator_alloc_region);
894 if (result != nullptr) {
895 return result;
896 }
897
898 // In a G1 heap, we're supposed to keep allocation from failing by
899 // incremental pauses. Therefore, at least for now, we'll favor
900 // expansion over collection. (This might change in the future if we can
901 // do something smarter than full collection to satisfy a failed alloc.)
902 result = expand_and_allocate(word_size);
903 if (result != nullptr) {
904 return result;
905 }
906
907 if (do_gc) {
908 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
909 // Expansion didn't work, we'll try to do a Full GC.
910 // If maximal_compaction is set we clear all soft references and don't
911 // allow any dead wood to be left on the heap.
912 if (maximal_compaction) {
913 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
914 } else {
915 log_info(gc, ergo)("Attempting full compaction");
916 }
917 *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ ,
918 maximal_compaction /* do_maximal_compaction */);
919 }
920
921 return nullptr;
922 }
923
924 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
925 bool* succeeded) {
926 assert_at_safepoint_on_vm_thread();
927
928 // Attempts to allocate followed by Full GC.
929 HeapWord* result =
930 satisfy_failed_allocation_helper(word_size,
931 true, /* do_gc */
932 false, /* maximum_collection */
933 false, /* expect_null_mutator_alloc_region */
934 succeeded);
935
936 if (result != nullptr || !*succeeded) {
937 return result;
938 }
939
940 // Attempts to allocate followed by Full GC that will collect all soft references.
941 result = satisfy_failed_allocation_helper(word_size,
942 true, /* do_gc */
943 true, /* maximum_collection */
944 true, /* expect_null_mutator_alloc_region */
945 succeeded);
946
947 if (result != nullptr || !*succeeded) {
948 return result;
949 }
950
951 // Attempts to allocate, no GC
952 result = satisfy_failed_allocation_helper(word_size,
953 false, /* do_gc */
954 false, /* maximum_collection */
955 true, /* expect_null_mutator_alloc_region */
956 succeeded);
957
958 if (result != nullptr) {
959 return result;
960 }
961
962 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
963 "Flag should have been handled and cleared prior to this point");
964
965 // What else? We might try synchronous finalization later. If the total
966 // space available is large enough for the allocation, then a more
967 // complete compaction phase than we've tried so far might be
968 // appropriate.
969 return nullptr;
970 }
971
972 // Attempting to expand the heap sufficiently
973 // to support an allocation of the given "word_size". If
974 // successful, perform the allocation and return the address of the
975 // allocated block, or else null.
976
977 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
978 assert_at_safepoint_on_vm_thread();
979
980 _verifier->verify_region_sets_optional();
981
982 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
983 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
984 word_size * HeapWordSize);
985
986
987 if (expand(expand_bytes, _workers)) {
988 _hrm.verify_optional();
989 _verifier->verify_region_sets_optional();
990 return attempt_allocation_at_safepoint(word_size,
991 false /* expect_null_mutator_alloc_region */);
992 }
993 return nullptr;
994 }
995
996 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
997 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
998 aligned_expand_bytes = align_up(aligned_expand_bytes,
999 HeapRegion::GrainBytes);
1000
1001 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1002 expand_bytes, aligned_expand_bytes);
1003
1004 if (is_maximal_no_gc()) {
1005 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1006 return false;
1007 }
1008
1009 double expand_heap_start_time_sec = os::elapsedTime();
1010 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1011 assert(regions_to_expand > 0, "Must expand by at least one region");
1012
1013 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1014 if (expand_time_ms != nullptr) {
1015 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1016 }
1017
1018 assert(expanded_by > 0, "must have failed during commit.");
1019
1020 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1021 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1022 policy()->record_new_heap_size(num_regions());
1023
1024 return true;
1025 }
1026
1027 bool G1CollectedHeap::expand_single_region(uint node_index) {
1028 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1029
1030 if (expanded_by == 0) {
1031 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1032 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1033 return false;
1034 }
1035
1036 policy()->record_new_heap_size(num_regions());
1037 return true;
1038 }
1039
1040 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1041 size_t aligned_shrink_bytes =
1042 ReservedSpace::page_align_size_down(shrink_bytes);
1043 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1044 HeapRegion::GrainBytes);
1045 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1046
1047 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1048 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1049
1050 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",
1051 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1052 if (num_regions_removed > 0) {
1053 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1054 policy()->record_new_heap_size(num_regions());
1055 } else {
1056 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1057 }
1058 }
1059
1060 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1061 _verifier->verify_region_sets_optional();
1062
1063 // We should only reach here at the end of a Full GC or during Remark which
1064 // means we should not not be holding to any GC alloc regions. The method
1065 // below will make sure of that and do any remaining clean up.
1066 _allocator->abandon_gc_alloc_regions();
1067
1068 // Instead of tearing down / rebuilding the free lists here, we
1069 // could instead use the remove_all_pending() method on free_list to
1070 // remove only the ones that we need to remove.
1071 _hrm.remove_all_free_regions();
1072 shrink_helper(shrink_bytes);
1073 rebuild_region_sets(true /* free_list_only */);
1074
1075 _hrm.verify_optional();
1076 _verifier->verify_region_sets_optional();
1077 }
1078
1079 class OldRegionSetChecker : public HeapRegionSetChecker {
1080 public:
1081 void check_mt_safety() {
1082 // Master Old Set MT safety protocol:
1083 // (a) If we're at a safepoint, operations on the master old set
1084 // should be invoked:
1085 // - by the VM thread (which will serialize them), or
1086 // - by the GC workers while holding the FreeList_lock, if we're
1087 // at a safepoint for an evacuation pause (this lock is taken
1088 // anyway when an GC alloc region is retired so that a new one
1089 // is allocated from the free list), or
1090 // - by the GC workers while holding the OldSets_lock, if we're at a
1091 // safepoint for a cleanup pause.
1092 // (b) If we're not at a safepoint, operations on the master old set
1093 // should be invoked while holding the Heap_lock.
1094
1095 if (SafepointSynchronize::is_at_safepoint()) {
1096 guarantee(Thread::current()->is_VM_thread() ||
1097 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1098 "master old set MT safety protocol at a safepoint");
1099 } else {
1100 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1101 }
1102 }
1103 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1104 const char* get_description() { return "Old Regions"; }
1105 };
1106
1107 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1108 public:
1109 void check_mt_safety() {
1110 // Humongous Set MT safety protocol:
1111 // (a) If we're at a safepoint, operations on the master humongous
1112 // set should be invoked by either the VM thread (which will
1113 // serialize them) or by the GC workers while holding the
1114 // OldSets_lock.
1115 // (b) If we're not at a safepoint, operations on the master
1116 // humongous set should be invoked while holding the Heap_lock.
1117
1118 if (SafepointSynchronize::is_at_safepoint()) {
1119 guarantee(Thread::current()->is_VM_thread() ||
1120 OldSets_lock->owned_by_self(),
1121 "master humongous set MT safety protocol at a safepoint");
1122 } else {
1123 guarantee(Heap_lock->owned_by_self(),
1124 "master humongous set MT safety protocol outside a safepoint");
1125 }
1126 }
1127 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1128 const char* get_description() { return "Humongous Regions"; }
1129 };
1130
1131 G1CollectedHeap::G1CollectedHeap() :
1132 CollectedHeap(),
1133 _service_thread(nullptr),
1134 _periodic_gc_task(nullptr),
1135 _free_arena_memory_task(nullptr),
1136 _workers(nullptr),
1137 _card_table(nullptr),
1138 _collection_pause_end(Ticks::now()),
1139 _old_set("Old Region Set", new OldRegionSetChecker()),
1140 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1141 _bot(nullptr),
1142 _listener(),
1143 _numa(G1NUMA::create()),
1144 _hrm(),
1145 _allocator(nullptr),
1146 _allocation_failure_injector(),
1147 _verifier(nullptr),
1148 _summary_bytes_used(0),
1149 _bytes_used_during_gc(0),
1150 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1151 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1152 _monitoring_support(nullptr),
1153 _num_humongous_objects(0),
1154 _num_humongous_reclaim_candidates(0),
1155 _hr_printer(),
1156 _collector_state(),
1157 _old_marking_cycles_started(0),
1158 _old_marking_cycles_completed(0),
1159 _eden(),
1160 _survivor(),
1161 _gc_timer_stw(new STWGCTimer()),
1162 _gc_tracer_stw(new G1NewTracer()),
1163 _policy(new G1Policy(_gc_timer_stw)),
1164 _heap_sizing_policy(nullptr),
1165 _collection_set(this, _policy),
1166 _rem_set(nullptr),
1167 _card_set_config(),
1168 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1169 _cm(nullptr),
1170 _cm_thread(nullptr),
1171 _cr(nullptr),
1172 _task_queues(nullptr),
1173 _ref_processor_stw(nullptr),
1174 _is_alive_closure_stw(this),
1175 _is_subject_to_discovery_stw(this),
1176 _ref_processor_cm(nullptr),
1177 _is_alive_closure_cm(),
1178 _is_subject_to_discovery_cm(this),
1179 _region_attr() {
1180
1181 _verifier = new G1HeapVerifier(this);
1182
1183 _allocator = new G1Allocator(this);
1184
1185 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1186
1187 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1188
1189 // Since filler arrays are never referenced, we can make them region sized.
1190 // This simplifies filling up the region in case we have some potentially
1191 // unreferenced (by Java code, but still in use by native code) pinned objects
1192 // in there.
1193 _filler_array_max_size = HeapRegion::GrainWords;
1194
1195 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1196 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1197
1198 uint n_queues = ParallelGCThreads;
1199 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1200
1201 for (uint i = 0; i < n_queues; i++) {
1202 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1203 _task_queues->register_queue(i, q);
1204 }
1205
1206 _gc_tracer_stw->initialize();
1207
1208 guarantee(_task_queues != nullptr, "task_queues allocation failure.");
1209 }
1210
1211 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1212 size_t size,
1213 size_t translation_factor) {
1214 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1215 // Allocate a new reserved space, preferring to use large pages.
1216 ReservedSpace rs(size, preferred_page_size);
1217 size_t page_size = rs.page_size();
1218 G1RegionToSpaceMapper* result =
1219 G1RegionToSpaceMapper::create_mapper(rs,
1220 size,
1221 page_size,
1222 HeapRegion::GrainBytes,
1223 translation_factor,
1224 mtGC);
1225
1226 os::trace_page_sizes_for_requested_size(description,
1227 size,
1228 preferred_page_size,
1229 rs.base(),
1230 rs.size(),
1231 page_size);
1232
1233 return result;
1234 }
1235
1236 jint G1CollectedHeap::initialize_concurrent_refinement() {
1237 jint ecode = JNI_OK;
1238 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1239 return ecode;
1240 }
1241
1242 jint G1CollectedHeap::initialize_service_thread() {
1243 _service_thread = new G1ServiceThread();
1244 if (_service_thread->osthread() == nullptr) {
1245 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1246 return JNI_ENOMEM;
1247 }
1248 return JNI_OK;
1249 }
1250
1251 jint G1CollectedHeap::initialize() {
1252
1253 // Necessary to satisfy locking discipline assertions.
1254
1255 MutexLocker x(Heap_lock);
1256
1257 // While there are no constraints in the GC code that HeapWordSize
1258 // be any particular value, there are multiple other areas in the
1259 // system which believe this to be true (e.g. oop->object_size in some
1260 // cases incorrectly returns the size in wordSize units rather than
1261 // HeapWordSize).
1262 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1263
1264 size_t init_byte_size = InitialHeapSize;
1265 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1266
1267 // Ensure that the sizes are properly aligned.
1268 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1269 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1270 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1271
1272 // Reserve the maximum.
1273
1274 // When compressed oops are enabled, the preferred heap base
1275 // is calculated by subtracting the requested size from the
1276 // 32Gb boundary and using the result as the base address for
1277 // heap reservation. If the requested size is not aligned to
1278 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1279 // into the ReservedHeapSpace constructor) then the actual
1280 // base of the reserved heap may end up differing from the
1281 // address that was requested (i.e. the preferred heap base).
1282 // If this happens then we could end up using a non-optimal
1283 // compressed oops mode.
1284
1285 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1286 HeapAlignment);
1287
1288 initialize_reserved_region(heap_rs);
1289
1290 // Create the barrier set for the entire reserved region.
1291 G1CardTable* ct = new G1CardTable(heap_rs.region());
1292 G1BarrierSet* bs = new G1BarrierSet(ct);
1293 bs->initialize();
1294 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1295 BarrierSet::set_barrier_set(bs);
1296 _card_table = ct;
1297
1298 {
1299 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1300 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1301 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1302 }
1303
1304 // Create space mappers.
1305 size_t page_size = heap_rs.page_size();
1306 G1RegionToSpaceMapper* heap_storage =
1307 G1RegionToSpaceMapper::create_mapper(heap_rs,
1308 heap_rs.size(),
1309 page_size,
1310 HeapRegion::GrainBytes,
1311 1,
1312 mtJavaHeap);
1313 if(heap_storage == nullptr) {
1314 vm_shutdown_during_initialization("Could not initialize G1 heap");
1315 return JNI_ERR;
1316 }
1317
1318 os::trace_page_sizes("Heap",
1319 MinHeapSize,
1320 reserved_byte_size,
1321 heap_rs.base(),
1322 heap_rs.size(),
1323 page_size);
1324 heap_storage->set_mapping_changed_listener(&_listener);
1325
1326 // Create storage for the BOT, card table and the bitmap.
1327 G1RegionToSpaceMapper* bot_storage =
1328 create_aux_memory_mapper("Block Offset Table",
1329 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1330 G1BlockOffsetTable::heap_map_factor());
1331
1332 G1RegionToSpaceMapper* cardtable_storage =
1333 create_aux_memory_mapper("Card Table",
1334 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1335 G1CardTable::heap_map_factor());
1336
1337 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1338 G1RegionToSpaceMapper* bitmap_storage =
1339 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1340
1341 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1342 _card_table->initialize(cardtable_storage);
1343
1344 // 6843694 - ensure that the maximum region index can fit
1345 // in the remembered set structures.
1346 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1347 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1348
1349 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1350 // start within the first card.
1351 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1352 G1FromCardCache::initialize(max_reserved_regions());
1353 // Also create a G1 rem set.
1354 _rem_set = new G1RemSet(this, _card_table);
1355 _rem_set->initialize(max_reserved_regions());
1356
1357 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1358 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1359 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1360 "too many cards per region");
1361
1362 HeapRegionRemSet::initialize(_reserved);
1363
1364 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1365
1366 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1367
1368 {
1369 size_t granularity = HeapRegion::GrainBytes;
1370
1371 _region_attr.initialize(reserved(), granularity);
1372 }
1373
1374 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1375 if (_workers == nullptr) {
1376 return JNI_ENOMEM;
1377 }
1378 _workers->initialize_workers();
1379
1380 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1381
1382 // Create the G1ConcurrentMark data structure and thread.
1383 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1384 _cm = new G1ConcurrentMark(this, bitmap_storage);
1385 _cm_thread = _cm->cm_thread();
1386
1387 // Now expand into the initial heap size.
1388 if (!expand(init_byte_size, _workers)) {
1389 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1390 return JNI_ENOMEM;
1391 }
1392
1393 // Perform any initialization actions delegated to the policy.
1394 policy()->init(this, &_collection_set);
1395
1396 jint ecode = initialize_concurrent_refinement();
1397 if (ecode != JNI_OK) {
1398 return ecode;
1399 }
1400
1401 ecode = initialize_service_thread();
1402 if (ecode != JNI_OK) {
1403 return ecode;
1404 }
1405
1406 // Create and schedule the periodic gc task on the service thread.
1407 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1408 _service_thread->register_task(_periodic_gc_task);
1409
1410 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1411 _service_thread->register_task(_free_arena_memory_task);
1412
1413 // Here we allocate the dummy HeapRegion that is required by the
1414 // G1AllocRegion class.
1415 HeapRegion* dummy_region = _hrm.get_dummy_region();
1416
1417 // We'll re-use the same region whether the alloc region will
1418 // require BOT updates or not and, if it doesn't, then a non-young
1419 // region will complain that it cannot support allocations without
1420 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1421 dummy_region->set_eden();
1422 // Make sure it's full.
1423 dummy_region->set_top(dummy_region->end());
1424 G1AllocRegion::setup(this, dummy_region);
1425
1426 _allocator->init_mutator_alloc_regions();
1427
1428 // Do create of the monitoring and management support so that
1429 // values in the heap have been properly initialized.
1430 _monitoring_support = new G1MonitoringSupport(this);
1431
1432 _collection_set.initialize(max_reserved_regions());
1433
1434 allocation_failure_injector()->reset();
1435
1436 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_parallel_workers);
1437 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_conc_mark);
1438 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_conc_refine);
1439 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_service);
1440
1441 G1InitLogger::print();
1442
1443 return JNI_OK;
1444 }
1445
1446 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1447 return _cm_thread->should_terminate();
1448 }
1449
1450 void G1CollectedHeap::stop() {
1451 // Stop all concurrent threads. We do this to make sure these threads
1452 // do not continue to execute and access resources (e.g. logging)
1453 // that are destroyed during shutdown.
1454 _cr->stop();
1455 _service_thread->stop();
1456 _cm_thread->stop();
1457 }
1458
1459 void G1CollectedHeap::safepoint_synchronize_begin() {
1460 SuspendibleThreadSet::synchronize();
1461 }
1462
1463 void G1CollectedHeap::safepoint_synchronize_end() {
1464 SuspendibleThreadSet::desynchronize();
1465 }
1466
1467 void G1CollectedHeap::post_initialize() {
1468 CollectedHeap::post_initialize();
1469 ref_processing_init();
1470 }
1471
1472 void G1CollectedHeap::ref_processing_init() {
1473 // Reference processing in G1 currently works as follows:
1474 //
1475 // * There are two reference processor instances. One is
1476 // used to record and process discovered references
1477 // during concurrent marking; the other is used to
1478 // record and process references during STW pauses
1479 // (both full and incremental).
1480 // * Both ref processors need to 'span' the entire heap as
1481 // the regions in the collection set may be dotted around.
1482 //
1483 // * For the concurrent marking ref processor:
1484 // * Reference discovery is enabled at concurrent start.
1485 // * Reference discovery is disabled and the discovered
1486 // references processed etc during remarking.
1487 // * Reference discovery is MT (see below).
1488 // * Reference discovery requires a barrier (see below).
1489 // * Reference processing may or may not be MT
1490 // (depending on the value of ParallelRefProcEnabled
1491 // and ParallelGCThreads).
1492 // * A full GC disables reference discovery by the CM
1493 // ref processor and abandons any entries on it's
1494 // discovered lists.
1495 //
1496 // * For the STW processor:
1497 // * Non MT discovery is enabled at the start of a full GC.
1498 // * Processing and enqueueing during a full GC is non-MT.
1499 // * During a full GC, references are processed after marking.
1500 //
1501 // * Discovery (may or may not be MT) is enabled at the start
1502 // of an incremental evacuation pause.
1503 // * References are processed near the end of a STW evacuation pause.
1504 // * For both types of GC:
1505 // * Discovery is atomic - i.e. not concurrent.
1506 // * Reference discovery will not need a barrier.
1507
1508 _is_alive_closure_cm.initialize(concurrent_mark());
1509 // Concurrent Mark ref processor
1510 _ref_processor_cm =
1511 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1512 ParallelGCThreads, // degree of mt processing
1513 // We discover with the gc worker threads during Remark, so both
1514 // thread counts must be considered for discovery.
1515 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1516 true, // Reference discovery is concurrent
1517 &_is_alive_closure_cm); // is alive closure
1518
1519 // STW ref processor
1520 _ref_processor_stw =
1521 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1522 ParallelGCThreads, // degree of mt processing
1523 ParallelGCThreads, // degree of mt discovery
1524 false, // Reference discovery is not concurrent
1525 &_is_alive_closure_stw); // is alive closure
1526 }
1527
1528 size_t G1CollectedHeap::capacity() const {
1529 return _hrm.length() * HeapRegion::GrainBytes;
1530 }
1531
1532 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1533 return _hrm.total_free_bytes();
1534 }
1535
1536 // Computes the sum of the storage used by the various regions.
1537 size_t G1CollectedHeap::used() const {
1538 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1539 return result;
1540 }
1541
1542 size_t G1CollectedHeap::used_unlocked() const {
1543 return _summary_bytes_used;
1544 }
1545
1546 class SumUsedClosure: public HeapRegionClosure {
1547 size_t _used;
1548 public:
1549 SumUsedClosure() : _used(0) {}
1550 bool do_heap_region(HeapRegion* r) {
1551 _used += r->used();
1552 return false;
1553 }
1554 size_t result() { return _used; }
1555 };
1556
1557 size_t G1CollectedHeap::recalculate_used() const {
1558 SumUsedClosure blk;
1559 heap_region_iterate(&blk);
1560 return blk.result();
1561 }
1562
1563 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1564 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1565 }
1566
1567 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1568 switch (cause) {
1569 case GCCause::_g1_humongous_allocation: return true;
1570 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1571 case GCCause::_wb_breakpoint: return true;
1572 case GCCause::_codecache_GC_aggressive: return true;
1573 case GCCause::_codecache_GC_threshold: return true;
1574 default: return is_user_requested_concurrent_full_gc(cause);
1575 }
1576 }
1577
1578 void G1CollectedHeap::increment_old_marking_cycles_started() {
1579 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1580 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1581 "Wrong marking cycle count (started: %d, completed: %d)",
1582 _old_marking_cycles_started, _old_marking_cycles_completed);
1583
1584 _old_marking_cycles_started++;
1585 }
1586
1587 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1588 bool whole_heap_examined) {
1589 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1590
1591 // We assume that if concurrent == true, then the caller is a
1592 // concurrent thread that was joined the Suspendible Thread
1593 // Set. If there's ever a cheap way to check this, we should add an
1594 // assert here.
1595
1596 // Given that this method is called at the end of a Full GC or of a
1597 // concurrent cycle, and those can be nested (i.e., a Full GC can
1598 // interrupt a concurrent cycle), the number of full collections
1599 // completed should be either one (in the case where there was no
1600 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1601 // behind the number of full collections started.
1602
1603 // This is the case for the inner caller, i.e. a Full GC.
1604 assert(concurrent ||
1605 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1606 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1607 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1608 "is inconsistent with _old_marking_cycles_completed = %u",
1609 _old_marking_cycles_started, _old_marking_cycles_completed);
1610
1611 // This is the case for the outer caller, i.e. the concurrent cycle.
1612 assert(!concurrent ||
1613 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1614 "for outer caller (concurrent cycle): "
1615 "_old_marking_cycles_started = %u "
1616 "is inconsistent with _old_marking_cycles_completed = %u",
1617 _old_marking_cycles_started, _old_marking_cycles_completed);
1618
1619 _old_marking_cycles_completed += 1;
1620 if (whole_heap_examined) {
1621 // Signal that we have completed a visit to all live objects.
1622 record_whole_heap_examined_timestamp();
1623 }
1624
1625 // We need to clear the "in_progress" flag in the CM thread before
1626 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1627 // is set) so that if a waiter requests another System.gc() it doesn't
1628 // incorrectly see that a marking cycle is still in progress.
1629 if (concurrent) {
1630 _cm_thread->set_idle();
1631 }
1632
1633 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1634 // for a full GC to finish that their wait is over.
1635 ml.notify_all();
1636 }
1637
1638 // Helper for collect().
1639 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1640 MutexLocker ml(Heap_lock);
1641 return G1GCCounters(g1h);
1642 }
1643
1644 void G1CollectedHeap::collect(GCCause::Cause cause) {
1645 try_collect(cause, collection_counters(this));
1646 }
1647
1648 // Return true if (x < y) with allowance for wraparound.
1649 static bool gc_counter_less_than(uint x, uint y) {
1650 return (x - y) > (UINT_MAX/2);
1651 }
1652
1653 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1654 // Macro so msg printing is format-checked.
1655 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1656 do { \
1657 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1658 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1659 ResourceMark rm; /* For thread name. */ \
1660 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1661 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1662 Thread::current()->name(), \
1663 GCCause::to_string(cause)); \
1664 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1665 } \
1666 } while (0)
1667
1668 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1669 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1670
1671 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1672 uint gc_counter,
1673 uint old_marking_started_before) {
1674 assert_heap_not_locked();
1675 assert(should_do_concurrent_full_gc(cause),
1676 "Non-concurrent cause %s", GCCause::to_string(cause));
1677
1678 for (uint i = 1; true; ++i) {
1679 // Try to schedule concurrent start evacuation pause that will
1680 // start a concurrent cycle.
1681 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1682 VM_G1TryInitiateConcMark op(gc_counter, cause);
1683 VMThread::execute(&op);
1684
1685 // Request is trivially finished.
1686 if (cause == GCCause::_g1_periodic_collection) {
1687 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1688 return op.gc_succeeded();
1689 }
1690
1691 // If VMOp skipped initiating concurrent marking cycle because
1692 // we're terminating, then we're done.
1693 if (op.terminating()) {
1694 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1695 return false;
1696 }
1697
1698 // Lock to get consistent set of values.
1699 uint old_marking_started_after;
1700 uint old_marking_completed_after;
1701 {
1702 MutexLocker ml(Heap_lock);
1703 // Update gc_counter for retrying VMOp if needed. Captured here to be
1704 // consistent with the values we use below for termination tests. If
1705 // a retry is needed after a possible wait, and another collection
1706 // occurs in the meantime, it will cause our retry to be skipped and
1707 // we'll recheck for termination with updated conditions from that
1708 // more recent collection. That's what we want, rather than having
1709 // our retry possibly perform an unnecessary collection.
1710 gc_counter = total_collections();
1711 old_marking_started_after = _old_marking_cycles_started;
1712 old_marking_completed_after = _old_marking_cycles_completed;
1713 }
1714
1715 if (cause == GCCause::_wb_breakpoint) {
1716 if (op.gc_succeeded()) {
1717 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1718 return true;
1719 }
1720 // When _wb_breakpoint there can't be another cycle or deferred.
1721 assert(!op.cycle_already_in_progress(), "invariant");
1722 assert(!op.whitebox_attached(), "invariant");
1723 // Concurrent cycle attempt might have been cancelled by some other
1724 // collection, so retry. Unlike other cases below, we want to retry
1725 // even if cancelled by a STW full collection, because we really want
1726 // to start a concurrent cycle.
1727 if (old_marking_started_before != old_marking_started_after) {
1728 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1729 old_marking_started_before = old_marking_started_after;
1730 }
1731 } else if (!GCCause::is_user_requested_gc(cause)) {
1732 // For an "automatic" (not user-requested) collection, we just need to
1733 // ensure that progress is made.
1734 //
1735 // Request is finished if any of
1736 // (1) the VMOp successfully performed a GC,
1737 // (2) a concurrent cycle was already in progress,
1738 // (3) whitebox is controlling concurrent cycles,
1739 // (4) a new cycle was started (by this thread or some other), or
1740 // (5) a Full GC was performed.
1741 // Cases (4) and (5) are detected together by a change to
1742 // _old_marking_cycles_started.
1743 //
1744 // Note that (1) does not imply (4). If we're still in the mixed
1745 // phase of an earlier concurrent collection, the request to make the
1746 // collection a concurrent start won't be honored. If we don't check for
1747 // both conditions we'll spin doing back-to-back collections.
1748 if (op.gc_succeeded() ||
1749 op.cycle_already_in_progress() ||
1750 op.whitebox_attached() ||
1751 (old_marking_started_before != old_marking_started_after)) {
1752 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1753 return true;
1754 }
1755 } else { // User-requested GC.
1756 // For a user-requested collection, we want to ensure that a complete
1757 // full collection has been performed before returning, but without
1758 // waiting for more than needed.
1759
1760 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1761 // new cycle was started. That's good, because it's not clear what we
1762 // should do otherwise. Trying again just does back to back GCs.
1763 // Can't wait for someone else to start a cycle. And returning fails
1764 // to meet the goal of ensuring a full collection was performed.
1765 assert(!op.gc_succeeded() ||
1766 (old_marking_started_before != old_marking_started_after),
1767 "invariant: succeeded %s, started before %u, started after %u",
1768 BOOL_TO_STR(op.gc_succeeded()),
1769 old_marking_started_before, old_marking_started_after);
1770
1771 // Request is finished if a full collection (concurrent or stw)
1772 // was started after this request and has completed, e.g.
1773 // started_before < completed_after.
1774 if (gc_counter_less_than(old_marking_started_before,
1775 old_marking_completed_after)) {
1776 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1777 return true;
1778 }
1779
1780 if (old_marking_started_after != old_marking_completed_after) {
1781 // If there is an in-progress cycle (possibly started by us), then
1782 // wait for that cycle to complete, e.g.
1783 // while completed_now < started_after.
1784 LOG_COLLECT_CONCURRENTLY(cause, "wait");
1785 MonitorLocker ml(G1OldGCCount_lock);
1786 while (gc_counter_less_than(_old_marking_cycles_completed,
1787 old_marking_started_after)) {
1788 ml.wait();
1789 }
1790 // Request is finished if the collection we just waited for was
1791 // started after this request.
1792 if (old_marking_started_before != old_marking_started_after) {
1793 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
1794 return true;
1795 }
1796 }
1797
1798 // If VMOp was successful then it started a new cycle that the above
1799 // wait &etc should have recognized as finishing this request. This
1800 // differs from a non-user-request, where gc_succeeded does not imply
1801 // a new cycle was started.
1802 assert(!op.gc_succeeded(), "invariant");
1803
1804 if (op.cycle_already_in_progress()) {
1805 // If VMOp failed because a cycle was already in progress, it
1806 // is now complete. But it didn't finish this user-requested
1807 // GC, so try again.
1808 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
1809 continue;
1810 } else if (op.whitebox_attached()) {
1811 // If WhiteBox wants control, wait for notification of a state
1812 // change in the controller, then try again. Don't wait for
1813 // release of control, since collections may complete while in
1814 // control. Note: This won't recognize a STW full collection
1815 // while waiting; we can't wait on multiple monitors.
1816 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
1817 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
1818 if (ConcurrentGCBreakpoints::is_controlled()) {
1819 ml.wait();
1820 }
1821 continue;
1822 }
1823 }
1824
1825 // Collection failed and should be retried.
1826 assert(op.transient_failure(), "invariant");
1827
1828 LOG_COLLECT_CONCURRENTLY(cause, "retry");
1829 }
1830 }
1831
1832 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause,
1833 const G1GCCounters& counters_before) {
1834 assert_heap_not_locked();
1835
1836 while(true) {
1837 VM_G1CollectFull op(counters_before.total_collections(),
1838 counters_before.total_full_collections(),
1839 cause);
1840 VMThread::execute(&op);
1841
1842 // Request is trivially finished.
1843 if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) {
1844 return op.gc_succeeded();
1845 }
1846
1847 {
1848 MutexLocker ml(Heap_lock);
1849 if (counters_before.total_full_collections() != total_full_collections()) {
1850 return true;
1851 }
1852 }
1853 }
1854 }
1855
1856 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
1857 const G1GCCounters& counters_before) {
1858 if (should_do_concurrent_full_gc(cause)) {
1859 return try_collect_concurrently(cause,
1860 counters_before.total_collections(),
1861 counters_before.old_marking_cycles_started());
1862 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
1863 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1864
1865 // Schedule a standard evacuation pause. We're setting word_size
1866 // to 0 which means that we are not requesting a post-GC allocation.
1867 VM_G1CollectForAllocation op(0, /* word_size */
1868 counters_before.total_collections(),
1869 cause);
1870 VMThread::execute(&op);
1871 return op.gc_succeeded();
1872 } else {
1873 // Schedule a Full GC.
1874 return try_collect_fullgc(cause, counters_before);
1875 }
1876 }
1877
1878 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
1879 GCCauseSetter x(this, gc_cause);
1880
1881 // At this point we are supposed to start a concurrent cycle. We
1882 // will do so if one is not already in progress.
1883 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
1884 if (should_start) {
1885 do_collection_pause_at_safepoint();
1886 }
1887 }
1888
1889 bool G1CollectedHeap::is_in(const void* p) const {
1890 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
1891 }
1892
1893 // Iteration functions.
1894
1895 // Iterates an ObjectClosure over all objects within a HeapRegion.
1896
1897 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1898 ObjectClosure* _cl;
1899 public:
1900 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1901 bool do_heap_region(HeapRegion* r) {
1902 if (!r->is_continues_humongous()) {
1903 r->object_iterate(_cl);
1904 }
1905 return false;
1906 }
1907 };
1908
1909 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
1910 IterateObjectClosureRegionClosure blk(cl);
1911 heap_region_iterate(&blk);
1912 }
1913
1914 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
1915 private:
1916 G1CollectedHeap* _heap;
1917 HeapRegionClaimer _claimer;
1918
1919 public:
1920 G1ParallelObjectIterator(uint thread_num) :
1921 _heap(G1CollectedHeap::heap()),
1922 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
1923
1924 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1925 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
1926 }
1927 };
1928
1929 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
1930 return new G1ParallelObjectIterator(thread_num);
1931 }
1932
1933 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
1934 IterateObjectClosureRegionClosure blk(cl);
1935 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
1936 }
1937
1938 void G1CollectedHeap::keep_alive(oop obj) {
1939 G1BarrierSet::enqueue_preloaded(obj);
1940 }
1941
1942 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
1943 _hrm.iterate(cl);
1944 }
1945
1946 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
1947 _hrm.iterate(cl);
1948 }
1949
1950 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1951 HeapRegionClaimer *hrclaimer,
1952 uint worker_id) const {
1953 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
1954 }
1955
1956 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1957 HeapRegionClaimer *hrclaimer) const {
1958 _hrm.par_iterate(cl, hrclaimer, 0);
1959 }
1960
1961 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
1962 _collection_set.iterate(cl);
1963 }
1964
1965 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
1966 HeapRegionClaimer* hr_claimer,
1967 uint worker_id) {
1968 _collection_set.par_iterate(cl, hr_claimer, worker_id);
1969 }
1970
1971 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
1972 HeapRegionClaimer* hr_claimer,
1973 uint worker_id) {
1974 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
1975 }
1976
1977 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
1978 HeapRegionClaimer* hr_claimer,
1979 const uint regions[],
1980 size_t length,
1981 uint worker_id) const {
1982 assert_at_safepoint();
1983 if (length == 0) {
1984 return;
1985 }
1986 uint total_workers = workers()->active_workers();
1987
1988 size_t start_pos = (worker_id * length) / total_workers;
1989 size_t cur_pos = start_pos;
1990
1991 do {
1992 uint region_idx = regions[cur_pos];
1993 if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) {
1994 HeapRegion* r = region_at(region_idx);
1995 bool result = cl->do_heap_region(r);
1996 guarantee(!result, "Must not cancel iteration");
1997 }
1998
1999 cur_pos++;
2000 if (cur_pos == length) {
2001 cur_pos = 0;
2002 }
2003 } while (cur_pos != start_pos);
2004 }
2005
2006 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2007 HeapRegion* hr = heap_region_containing(addr);
2008 // The CollectedHeap API requires us to not fail for any given address within
2009 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2010 // outside of the allocated area.
2011 if (addr >= hr->top()) {
2012 return nullptr;
2013 }
2014 return hr->block_start(addr);
2015 }
2016
2017 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2018 HeapRegion* hr = heap_region_containing(addr);
2019 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2020 }
2021
2022 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2023 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2024 }
2025
2026 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2027 return _eden.length() * HeapRegion::GrainBytes;
2028 }
2029
2030 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2031 // must be equal to the humongous object limit.
2032 size_t G1CollectedHeap::max_tlab_size() const {
2033 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2034 }
2035
2036 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2037 return _allocator->unsafe_max_tlab_alloc();
2038 }
2039
2040 size_t G1CollectedHeap::max_capacity() const {
2041 return max_regions() * HeapRegion::GrainBytes;
2042 }
2043
2044 void G1CollectedHeap::prepare_for_verify() {
2045 _verifier->prepare_for_verify();
2046 }
2047
2048 void G1CollectedHeap::verify(VerifyOption vo) {
2049 _verifier->verify(vo);
2050 }
2051
2052 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2053 return true;
2054 }
2055
2056 class PrintRegionClosure: public HeapRegionClosure {
2057 outputStream* _st;
2058 public:
2059 PrintRegionClosure(outputStream* st) : _st(st) {}
2060 bool do_heap_region(HeapRegion* r) {
2061 r->print_on(_st);
2062 return false;
2063 }
2064 };
2065
2066 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2067 const HeapRegion* hr,
2068 const VerifyOption vo) const {
2069 switch (vo) {
2070 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2071 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2072 default: ShouldNotReachHere();
2073 }
2074 return false; // keep some compilers happy
2075 }
2076
2077 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2078 const VerifyOption vo) const {
2079 switch (vo) {
2080 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2081 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2082 default: ShouldNotReachHere();
2083 }
2084 return false; // keep some compilers happy
2085 }
2086
2087 void G1CollectedHeap::print_heap_regions() const {
2088 LogTarget(Trace, gc, heap, region) lt;
2089 if (lt.is_enabled()) {
2090 LogStream ls(lt);
2091 print_regions_on(&ls);
2092 }
2093 }
2094
2095 void G1CollectedHeap::print_on(outputStream* st) const {
2096 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2097 st->print(" %-20s", "garbage-first heap");
2098 st->print(" total reserved %zuK, committed %zuK, used %zuK",
2099 _hrm.reserved().byte_size()/K, capacity()/K, heap_used/K);
2100 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2101 p2i(_hrm.reserved().start()),
2102 p2i(_hrm.reserved().end()));
2103 st->cr();
2104 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2105 uint young_regions = young_regions_count();
2106 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2107 (size_t) young_regions * HeapRegion::GrainBytes / K);
2108 uint survivor_regions = survivor_regions_count();
2109 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2110 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2111 st->cr();
2112 if (_numa->is_enabled()) {
2113 uint num_nodes = _numa->num_active_nodes();
2114 st->print(" remaining free region(s) on each NUMA node: ");
2115 const uint* node_ids = _numa->node_ids();
2116 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2117 uint num_free_regions = _hrm.num_free_regions(node_index);
2118 st->print("%u=%u ", node_ids[node_index], num_free_regions);
2119 }
2120 st->cr();
2121 }
2122 MetaspaceUtils::print_on(st);
2123 }
2124
2125 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2126 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2127 "HS=humongous(starts), HC=humongous(continues), "
2128 "CS=collection set, F=free, "
2129 "TAMS=top-at-mark-start, "
2130 "PB=parsable bottom");
2131 PrintRegionClosure blk(st);
2132 heap_region_iterate(&blk);
2133 }
2134
2135 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2136 print_on(st);
2137
2138 // Print the per-region information.
2139 st->cr();
2140 print_regions_on(st);
2141 }
2142
2143 void G1CollectedHeap::print_on_error(outputStream* st) const {
2144 this->CollectedHeap::print_on_error(st);
2145
2146 if (_cm != nullptr) {
2147 st->cr();
2148 _cm->print_on_error(st);
2149 }
2150 }
2151
2152 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2153 workers()->threads_do(tc);
2154 tc->do_thread(_cm_thread);
2155 _cm->threads_do(tc);
2156 _cr->threads_do(tc);
2157 tc->do_thread(_service_thread);
2158 }
2159
2160 void G1CollectedHeap::print_tracing_info() const {
2161 rem_set()->print_summary_info();
2162 concurrent_mark()->print_summary_info();
2163 }
2164
2165 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2166 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2167 }
2168
2169 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2170
2171 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2172 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2173 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2174 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2175
2176 size_t eden_capacity_bytes =
2177 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2178
2179 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2180 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2181 survivor_used_bytes, old_gen_used_bytes, num_regions());
2182 }
2183
2184 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2185 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2186 stats->unused(), stats->used(), stats->region_end_waste(),
2187 stats->regions_filled(), stats->num_plab_filled(),
2188 stats->direct_allocated(), stats->num_direct_allocated(),
2189 stats->failure_used(), stats->failure_waste());
2190 }
2191
2192 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2193 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2194 gc_tracer->report_gc_heap_summary(when, heap_summary);
2195
2196 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2197 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2198 }
2199
2200 void G1CollectedHeap::gc_prologue(bool full) {
2201 // Update common counters.
2202 increment_total_collections(full /* full gc */);
2203 if (full || collector_state()->in_concurrent_start_gc()) {
2204 increment_old_marking_cycles_started();
2205 }
2206 }
2207
2208 void G1CollectedHeap::gc_epilogue(bool full) {
2209 // Update common counters.
2210 if (full) {
2211 // Update the number of full collections that have been completed.
2212 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2213 }
2214
2215 #if COMPILER2_OR_JVMCI
2216 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2217 #endif
2218
2219 // We have just completed a GC. Update the soft reference
2220 // policy with the new heap occupancy
2221 Universe::heap()->update_capacity_and_used_at_gc();
2222
2223 _collection_pause_end = Ticks::now();
2224
2225 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2226 &_collection_set_candidates_card_set_stats);
2227
2228 update_parallel_gc_threads_cpu_time();
2229 }
2230
2231 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2232 return _hrm.uncommit_inactive_regions(region_limit);
2233 }
2234
2235 bool G1CollectedHeap::has_uncommittable_regions() {
2236 return _hrm.has_inactive_regions();
2237 }
2238
2239 void G1CollectedHeap::uncommit_regions_if_necessary() {
2240 if (has_uncommittable_regions()) {
2241 G1UncommitRegionTask::enqueue();
2242 }
2243 }
2244
2245 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2246 LogTarget(Trace, gc, heap, verify) lt;
2247
2248 if (lt.is_enabled()) {
2249 LogStream ls(lt);
2250 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2251 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2252 heap_region_iterate(&cl);
2253 }
2254 }
2255
2256 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2257 uint gc_count_before,
2258 bool* succeeded,
2259 GCCause::Cause gc_cause) {
2260 assert_heap_not_locked_and_not_at_safepoint();
2261 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2262 VMThread::execute(&op);
2263
2264 HeapWord* result = op.result();
2265 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2266 assert(result == nullptr || ret_succeeded,
2267 "the result should be null if the VM did not succeed");
2268 *succeeded = ret_succeeded;
2269
2270 assert_heap_not_locked();
2271 return result;
2272 }
2273
2274 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2275 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2276
2277 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2278 if (concurrent_operation_is_full_mark) {
2279 _cm->post_concurrent_mark_start();
2280 _cm_thread->start_full_mark();
2281 } else {
2282 _cm->post_concurrent_undo_start();
2283 _cm_thread->start_undo_mark();
2284 }
2285 CGC_lock->notify();
2286 }
2287
2288 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2289 // We don't nominate objects with many remembered set entries, on
2290 // the assumption that such objects are likely still live.
2291 HeapRegionRemSet* rem_set = r->rem_set();
2292
2293 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2294 }
2295
2296 #ifndef PRODUCT
2297 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2298 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2299 public:
2300 virtual bool do_heap_region(HeapRegion* r) {
2301 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2302 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2303 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2304 "Region %u remset tracking status (%s) different to region attribute (%s)",
2305 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2306 return false;
2307 }
2308 } cl;
2309 heap_region_iterate(&cl);
2310 }
2311 #endif
2312
2313 void G1CollectedHeap::update_parallel_gc_threads_cpu_time() {
2314 assert(Thread::current()->is_VM_thread(),
2315 "Must be called from VM thread to avoid races");
2316 if (!UsePerfData || !os::is_thread_cpu_time_supported()) {
2317 return;
2318 }
2319
2320 // Ensure ThreadTotalCPUTimeClosure destructor is called before publishing gc
2321 // time.
2322 {
2323 ThreadTotalCPUTimeClosure tttc(CPUTimeGroups::CPUTimeType::gc_parallel_workers);
2324 // Currently parallel worker threads never terminate (JDK-8081682), so it is
2325 // safe for VMThread to read their CPU times. However, if JDK-8087340 is
2326 // resolved so they terminate, we should rethink if it is still safe.
2327 workers()->threads_do(&tttc);
2328 }
2329
2330 CPUTimeCounters::publish_gc_total_cpu_time();
2331 }
2332
2333 void G1CollectedHeap::start_new_collection_set() {
2334 collection_set()->start_incremental_building();
2335
2336 clear_region_attr();
2337
2338 guarantee(_eden.length() == 0, "eden should have been cleared");
2339 policy()->transfer_survivors_to_cset(survivor());
2340
2341 // We redo the verification but now wrt to the new CSet which
2342 // has just got initialized after the previous CSet was freed.
2343 _cm->verify_no_collection_set_oops();
2344 }
2345
2346 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2347 if (collector_state()->in_concurrent_start_gc()) {
2348 return G1HeapVerifier::G1VerifyConcurrentStart;
2349 } else if (collector_state()->in_young_only_phase()) {
2350 return G1HeapVerifier::G1VerifyYoungNormal;
2351 } else {
2352 return G1HeapVerifier::G1VerifyMixed;
2353 }
2354 }
2355
2356 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2357 if (!VerifyBeforeGC) {
2358 return;
2359 }
2360 if (!G1HeapVerifier::should_verify(type)) {
2361 return;
2362 }
2363 Ticks start = Ticks::now();
2364 _verifier->prepare_for_verify();
2365 _verifier->verify_region_sets_optional();
2366 _verifier->verify_dirty_young_regions();
2367 _verifier->verify_before_gc();
2368 verify_numa_regions("GC Start");
2369 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2370 }
2371
2372 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2373 if (!VerifyAfterGC) {
2374 return;
2375 }
2376 if (!G1HeapVerifier::should_verify(type)) {
2377 return;
2378 }
2379 Ticks start = Ticks::now();
2380 _verifier->verify_after_gc();
2381 verify_numa_regions("GC End");
2382 _verifier->verify_region_sets_optional();
2383
2384 if (collector_state()->in_concurrent_start_gc()) {
2385 log_debug(gc, verify)("Marking state");
2386 _verifier->verify_marking_state();
2387 }
2388
2389 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2390 }
2391
2392 void G1CollectedHeap::expand_heap_after_young_collection(){
2393 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2394 if (expand_bytes > 0) {
2395 // No need for an ergo logging here,
2396 // expansion_amount() does this when it returns a value > 0.
2397 double expand_ms = 0.0;
2398 if (!expand(expand_bytes, _workers, &expand_ms)) {
2399 // We failed to expand the heap. Cannot do anything about it.
2400 }
2401 phase_times()->record_expand_heap_time(expand_ms);
2402 }
2403 }
2404
2405 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2406 assert_at_safepoint_on_vm_thread();
2407 guarantee(!is_gc_active(), "collection is not reentrant");
2408
2409 do_collection_pause_at_safepoint_helper();
2410 return true;
2411 }
2412
2413 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2414 // This summary needs to be printed before incrementing total collections.
2415 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2416 _g1h->total_collections(),
2417 true /* show_thread_times */);
2418 _g1h->print_heap_before_gc();
2419 _g1h->print_heap_regions();
2420 }
2421
2422 G1HeapPrinterMark::~G1HeapPrinterMark() {
2423 _g1h->policy()->print_age_table();
2424 _g1h->rem_set()->print_coarsen_stats();
2425 // We are at the end of the GC. Total collections has already been increased.
2426 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2427 _g1h->total_collections() - 1,
2428 false /* show_thread_times */);
2429
2430 _heap_transition.print();
2431 _g1h->print_heap_regions();
2432 _g1h->print_heap_after_gc();
2433 // Print NUMA statistics.
2434 _g1h->numa()->print_statistics();
2435 }
2436
2437 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2438 _timer(timer), _tracer(tracer) {
2439
2440 _timer->register_gc_start();
2441 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2442 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2443 }
2444
2445 G1JFRTracerMark::~G1JFRTracerMark() {
2446 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2447 _timer->register_gc_end();
2448 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2449 }
2450
2451 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2452 Ticks start = Ticks::now();
2453
2454 _survivor_evac_stats.adjust_desired_plab_size();
2455 _old_evac_stats.adjust_desired_plab_size();
2456
2457 // Start a new incremental collection set for the mutator phase.
2458 start_new_collection_set();
2459 _allocator->init_mutator_alloc_regions();
2460
2461 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2462 }
2463
2464 void G1CollectedHeap::retire_tlabs() {
2465 ensure_parsability(true);
2466 }
2467
2468 void G1CollectedHeap::flush_region_pin_cache() {
2469 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
2470 G1ThreadLocalData::pin_count_cache(thread).flush();
2471 }
2472 }
2473
2474 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2475 ResourceMark rm;
2476
2477 IsGCActiveMark active_gc_mark;
2478 GCIdMark gc_id_mark;
2479 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2480
2481 GCTraceCPUTime tcpu(_gc_tracer_stw);
2482
2483 _bytes_used_during_gc = 0;
2484
2485 policy()->decide_on_concurrent_start_pause();
2486 // Record whether this pause may need to trigger a concurrent operation. Later,
2487 // when we signal the G1ConcurrentMarkThread, the collector state has already
2488 // been reset for the next pause.
2489 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2490
2491 // Perform the collection.
2492 G1YoungCollector collector(gc_cause());
2493 collector.collect();
2494
2495 // It should now be safe to tell the concurrent mark thread to start
2496 // without its logging output interfering with the logging output
2497 // that came from the pause.
2498 if (should_start_concurrent_mark_operation) {
2499 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2500 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2501 // thread(s) could be running concurrently with us. Make sure that anything
2502 // after this point does not assume that we are the only GC thread running.
2503 // Note: of course, the actual marking work will not start until the safepoint
2504 // itself is released in SuspendibleThreadSet::desynchronize().
2505 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2506 ConcurrentGCBreakpoints::notify_idle_to_active();
2507 }
2508 }
2509
2510 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2511 uint num_workers = workers()->active_workers();
2512 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2513 workers()->run_task(&unlink_task);
2514 }
2515
2516 void G1CollectedHeap::unload_classes_and_code(const char* description, BoolObjectClosure* is_alive, GCTimer* timer) {
2517 GCTraceTime(Debug, gc, phases) debug(description, timer);
2518
2519 ClassUnloadingContext ctx(workers()->active_workers(),
2520 false /* unregister_nmethods_during_purge */,
2521 false /* lock_nmethod_free_separately */);
2522 {
2523 CodeCache::UnlinkingScope scope(is_alive);
2524 bool unloading_occurred = SystemDictionary::do_unloading(timer);
2525 GCTraceTime(Debug, gc, phases) t("G1 Complete Cleaning", timer);
2526 complete_cleaning(unloading_occurred);
2527 }
2528 {
2529 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", timer);
2530 ctx.purge_nmethods();
2531 }
2532 {
2533 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", timer);
2534 G1CollectedHeap::heap()->bulk_unregister_nmethods();
2535 }
2536 {
2537 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", timer);
2538 ctx.free_nmethods();
2539 }
2540 {
2541 GCTraceTime(Debug, gc, phases) t("Purge Class Loader Data", timer);
2542 ClassLoaderDataGraph::purge(true /* at_safepoint */);
2543 DEBUG_ONLY(MetaspaceUtils::verify();)
2544 }
2545 }
2546
2547 class G1BulkUnregisterNMethodTask : public WorkerTask {
2548 HeapRegionClaimer _hrclaimer;
2549
2550 class UnregisterNMethodsHeapRegionClosure : public HeapRegionClosure {
2551 public:
2552
2553 bool do_heap_region(HeapRegion* hr) {
2554 hr->rem_set()->bulk_remove_code_roots();
2555 return false;
2556 }
2557 } _cl;
2558
2559 public:
2560 G1BulkUnregisterNMethodTask(uint num_workers)
2561 : WorkerTask("G1 Remove Unlinked NMethods From Code Root Set Task"),
2562 _hrclaimer(num_workers) { }
2563
2564 void work(uint worker_id) {
2565 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&_cl, &_hrclaimer, worker_id);
2566 }
2567 };
2568
2569 void G1CollectedHeap::bulk_unregister_nmethods() {
2570 uint num_workers = workers()->active_workers();
2571 G1BulkUnregisterNMethodTask t(num_workers);
2572 workers()->run_task(&t);
2573 }
2574
2575 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2576 assert(obj != nullptr, "must not be null");
2577 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2578 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2579 // may falsely indicate that this is not the case here: however the collection set only
2580 // contains old regions when concurrent mark is not running.
2581 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2582 }
2583
2584 void G1CollectedHeap::make_pending_list_reachable() {
2585 if (collector_state()->in_concurrent_start_gc()) {
2586 oop pll_head = Universe::reference_pending_list();
2587 if (pll_head != nullptr) {
2588 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2589 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2590 }
2591 }
2592 }
2593
2594 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2595 _num_humongous_objects = num_humongous_total;
2596 _num_humongous_reclaim_candidates = num_humongous_candidates;
2597 }
2598
2599 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2600 const G1CollectionSetCandidates* candidates = collection_set()->candidates();
2601 return !candidates->is_empty();
2602 }
2603
2604 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2605 _collection_set_candidates_card_set_stats = stats;
2606 }
2607
2608 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2609 _young_gen_card_set_stats = stats;
2610 }
2611
2612 void G1CollectedHeap::record_obj_copy_mem_stats() {
2613 policy()->old_gen_alloc_tracker()->
2614 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2615
2616 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2617 create_g1_evac_summary(&_old_evac_stats));
2618 }
2619
2620 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2621 concurrent_mark()->clear_bitmap_for_region(hr);
2622 }
2623
2624 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2625 assert(!hr->is_free(), "the region should not be free");
2626 assert(!hr->is_empty(), "the region should not be empty");
2627 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2628 assert(!hr->has_pinned_objects(),
2629 "must not free a region which contains pinned objects");
2630
2631 // Reset region metadata to allow reuse.
2632 hr->hr_clear(true /* clear_space */);
2633 _policy->remset_tracker()->update_at_free(hr);
2634
2635 if (free_list != nullptr) {
2636 free_list->add_ordered(hr);
2637 }
2638 }
2639
2640 void G1CollectedHeap::retain_region(HeapRegion* hr) {
2641 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
2642 collection_set()->candidates()->add_retained_region_unsorted(hr);
2643 }
2644
2645 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2646 FreeRegionList* free_list) {
2647 assert(hr->is_humongous(), "this is only for humongous regions");
2648 hr->clear_humongous();
2649 free_region(hr, free_list);
2650 }
2651
2652 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2653 const uint humongous_regions_removed) {
2654 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
2655 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2656 _old_set.bulk_remove(old_regions_removed);
2657 _humongous_set.bulk_remove(humongous_regions_removed);
2658 }
2659
2660 }
2661
2662 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2663 assert(list != nullptr, "list can't be null");
2664 if (!list->is_empty()) {
2665 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2666 _hrm.insert_list_into_free_list(list);
2667 }
2668 }
2669
2670 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2671 decrease_used(bytes);
2672 }
2673
2674 void G1CollectedHeap::clear_eden() {
2675 _eden.clear();
2676 }
2677
2678 void G1CollectedHeap::clear_collection_set() {
2679 collection_set()->clear();
2680 }
2681
2682 void G1CollectedHeap::rebuild_free_region_list() {
2683 Ticks start = Ticks::now();
2684 _hrm.rebuild_free_list(workers());
2685 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2686 }
2687
2688 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2689 public:
2690 virtual bool do_heap_region(HeapRegion* r) {
2691 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2692 G1CollectedHeap::heap()->clear_region_attr(r);
2693 r->clear_young_index_in_cset();
2694 return false;
2695 }
2696 };
2697
2698 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2699 G1AbandonCollectionSetClosure cl;
2700 collection_set_iterate_all(&cl);
2701
2702 collection_set->clear();
2703 collection_set->stop_incremental_building();
2704 }
2705
2706 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2707 return _allocator->is_retained_old_region(hr);
2708 }
2709
2710 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2711 _eden.add(hr);
2712 _policy->set_region_eden(hr);
2713 }
2714
2715 #ifdef ASSERT
2716
2717 class NoYoungRegionsClosure: public HeapRegionClosure {
2718 private:
2719 bool _success;
2720 public:
2721 NoYoungRegionsClosure() : _success(true) { }
2722 bool do_heap_region(HeapRegion* r) {
2723 if (r->is_young()) {
2724 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2725 p2i(r->bottom()), p2i(r->end()));
2726 _success = false;
2727 }
2728 return false;
2729 }
2730 bool success() { return _success; }
2731 };
2732
2733 bool G1CollectedHeap::check_young_list_empty() {
2734 bool ret = (young_regions_count() == 0);
2735
2736 NoYoungRegionsClosure closure;
2737 heap_region_iterate(&closure);
2738 ret = ret && closure.success();
2739
2740 return ret;
2741 }
2742
2743 #endif // ASSERT
2744
2745 // Remove the given HeapRegion from the appropriate region set.
2746 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2747 if (hr->is_humongous()) {
2748 _humongous_set.remove(hr);
2749 } else if (hr->is_old()) {
2750 _old_set.remove(hr);
2751 } else if (hr->is_young()) {
2752 // Note that emptying the eden and survivor lists is postponed and instead
2753 // done as the first step when rebuilding the regions sets again. The reason
2754 // for this is that during a full GC string deduplication needs to know if
2755 // a collected region was young or old when the full GC was initiated.
2756 hr->uninstall_surv_rate_group();
2757 } else {
2758 // We ignore free regions, we'll empty the free list afterwards.
2759 assert(hr->is_free(), "it cannot be another type");
2760 }
2761 }
2762
2763 void G1CollectedHeap::increase_used(size_t bytes) {
2764 _summary_bytes_used += bytes;
2765 }
2766
2767 void G1CollectedHeap::decrease_used(size_t bytes) {
2768 assert(_summary_bytes_used >= bytes,
2769 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2770 _summary_bytes_used, bytes);
2771 _summary_bytes_used -= bytes;
2772 }
2773
2774 void G1CollectedHeap::set_used(size_t bytes) {
2775 _summary_bytes_used = bytes;
2776 }
2777
2778 class RebuildRegionSetsClosure : public HeapRegionClosure {
2779 private:
2780 bool _free_list_only;
2781
2782 HeapRegionSet* _old_set;
2783 HeapRegionSet* _humongous_set;
2784
2785 HeapRegionManager* _hrm;
2786
2787 size_t _total_used;
2788
2789 public:
2790 RebuildRegionSetsClosure(bool free_list_only,
2791 HeapRegionSet* old_set,
2792 HeapRegionSet* humongous_set,
2793 HeapRegionManager* hrm) :
2794 _free_list_only(free_list_only), _old_set(old_set),
2795 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2796 assert(_hrm->num_free_regions() == 0, "pre-condition");
2797 if (!free_list_only) {
2798 assert(_old_set->is_empty(), "pre-condition");
2799 assert(_humongous_set->is_empty(), "pre-condition");
2800 }
2801 }
2802
2803 bool do_heap_region(HeapRegion* r) {
2804 if (r->is_empty()) {
2805 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2806 // Add free regions to the free list
2807 r->set_free();
2808 _hrm->insert_into_free_list(r);
2809 } else if (!_free_list_only) {
2810 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2811
2812 if (r->is_humongous()) {
2813 _humongous_set->add(r);
2814 } else {
2815 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2816 // We now move all (non-humongous, non-old) regions to old gen,
2817 // and register them as such.
2818 r->move_to_old();
2819 _old_set->add(r);
2820 }
2821 _total_used += r->used();
2822 }
2823
2824 return false;
2825 }
2826
2827 size_t total_used() {
2828 return _total_used;
2829 }
2830 };
2831
2832 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2833 assert_at_safepoint_on_vm_thread();
2834
2835 if (!free_list_only) {
2836 _eden.clear();
2837 _survivor.clear();
2838 }
2839
2840 RebuildRegionSetsClosure cl(free_list_only,
2841 &_old_set, &_humongous_set,
2842 &_hrm);
2843 heap_region_iterate(&cl);
2844
2845 if (!free_list_only) {
2846 set_used(cl.total_used());
2847 }
2848 assert_used_and_recalculate_used_equal(this);
2849 }
2850
2851 // Methods for the mutator alloc region
2852
2853 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2854 bool force,
2855 uint node_index) {
2856 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2857 bool should_allocate = policy()->should_allocate_mutator_region();
2858 if (force || should_allocate) {
2859 HeapRegion* new_alloc_region = new_region(word_size,
2860 HeapRegionType::Eden,
2861 false /* do_expand */,
2862 node_index);
2863 if (new_alloc_region != nullptr) {
2864 set_region_short_lived_locked(new_alloc_region);
2865 _hr_printer.alloc(new_alloc_region, !should_allocate);
2866 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2867 return new_alloc_region;
2868 }
2869 }
2870 return nullptr;
2871 }
2872
2873 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
2874 size_t allocated_bytes) {
2875 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2876 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
2877
2878 collection_set()->add_eden_region(alloc_region);
2879 increase_used(allocated_bytes);
2880 _eden.add_used_bytes(allocated_bytes);
2881 _hr_printer.retire(alloc_region);
2882
2883 // We update the eden sizes here, when the region is retired,
2884 // instead of when it's allocated, since this is the point that its
2885 // used space has been recorded in _summary_bytes_used.
2886 monitoring_support()->update_eden_size();
2887 }
2888
2889 // Methods for the GC alloc regions
2890
2891 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
2892 if (dest.is_old()) {
2893 return true;
2894 } else {
2895 return survivor_regions_count() < policy()->max_survivor_regions();
2896 }
2897 }
2898
2899 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
2900 assert(FreeList_lock->owned_by_self(), "pre-condition");
2901
2902 if (!has_more_regions(dest)) {
2903 return nullptr;
2904 }
2905
2906 HeapRegionType type;
2907 if (dest.is_young()) {
2908 type = HeapRegionType::Survivor;
2909 } else {
2910 type = HeapRegionType::Old;
2911 }
2912
2913 HeapRegion* new_alloc_region = new_region(word_size,
2914 type,
2915 true /* do_expand */,
2916 node_index);
2917
2918 if (new_alloc_region != nullptr) {
2919 if (type.is_survivor()) {
2920 new_alloc_region->set_survivor();
2921 _survivor.add(new_alloc_region);
2922 register_new_survivor_region_with_region_attr(new_alloc_region);
2923 } else {
2924 new_alloc_region->set_old();
2925 }
2926 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2927 register_region_with_region_attr(new_alloc_region);
2928 _hr_printer.alloc(new_alloc_region);
2929 return new_alloc_region;
2930 }
2931 return nullptr;
2932 }
2933
2934 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
2935 size_t allocated_bytes,
2936 G1HeapRegionAttr dest) {
2937 _bytes_used_during_gc += allocated_bytes;
2938 if (dest.is_old()) {
2939 old_set_add(alloc_region);
2940 } else {
2941 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
2942 _survivor.add_used_bytes(allocated_bytes);
2943 }
2944
2945 bool const during_im = collector_state()->in_concurrent_start_gc();
2946 if (during_im && allocated_bytes > 0) {
2947 _cm->add_root_region(alloc_region);
2948 }
2949 _hr_printer.retire(alloc_region);
2950 }
2951
2952 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
2953 bool expanded = false;
2954 uint index = _hrm.find_highest_free(&expanded);
2955
2956 if (index != G1_NO_HRM_INDEX) {
2957 if (expanded) {
2958 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
2959 HeapRegion::GrainWords * HeapWordSize);
2960 }
2961 return _hrm.allocate_free_regions_starting_at(index, 1);
2962 }
2963 return nullptr;
2964 }
2965
2966 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
2967 assert(!_cm->is_marked_in_bitmap(obj), "must be");
2968
2969 _cm->raw_mark_in_bitmap(obj);
2970 }
2971
2972 // Optimized nmethod scanning
2973 class RegisterNMethodOopClosure: public OopClosure {
2974 G1CollectedHeap* _g1h;
2975 nmethod* _nm;
2976
2977 public:
2978 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
2979 _g1h(g1h), _nm(nm) {}
2980
2981 void do_oop(oop* p) {
2982 oop heap_oop = RawAccess<>::oop_load(p);
2983 if (!CompressedOops::is_null(heap_oop)) {
2984 oop obj = CompressedOops::decode_not_null(heap_oop);
2985 HeapRegion* hr = _g1h->heap_region_containing(obj);
2986 assert(!hr->is_continues_humongous(),
2987 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
2988 " starting at " HR_FORMAT,
2989 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
2990
2991 hr->add_code_root(_nm);
2992 }
2993 }
2994
2995 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2996 };
2997
2998 void G1CollectedHeap::register_nmethod(nmethod* nm) {
2999 guarantee(nm != nullptr, "sanity");
3000 RegisterNMethodOopClosure reg_cl(this, nm);
3001 nm->oops_do(®_cl);
3002 }
3003
3004 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3005 // We always unregister nmethods in bulk during code unloading only.
3006 ShouldNotReachHere();
3007 }
3008
3009 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3010 if (evacuation_failed) {
3011 set_used(recalculate_used());
3012 } else {
3013 // The "used" of the collection set have already been subtracted
3014 // when they were freed. Add in the bytes used.
3015 increase_used(_bytes_used_during_gc);
3016 }
3017 }
3018
3019 class RebuildCodeRootClosure: public NMethodClosure {
3020 G1CollectedHeap* _g1h;
3021
3022 public:
3023 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3024 _g1h(g1h) {}
3025
3026 void do_nmethod(nmethod* nm) {
3027 assert(nm != nullptr, "Sanity");
3028 _g1h->register_nmethod(nm);
3029 }
3030 };
3031
3032 void G1CollectedHeap::rebuild_code_roots() {
3033 RebuildCodeRootClosure nmethod_cl(this);
3034 CodeCache::nmethods_do(&nmethod_cl);
3035 }
3036
3037 void G1CollectedHeap::initialize_serviceability() {
3038 _monitoring_support->initialize_serviceability();
3039 }
3040
3041 MemoryUsage G1CollectedHeap::memory_usage() {
3042 return _monitoring_support->memory_usage();
3043 }
3044
3045 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3046 return _monitoring_support->memory_managers();
3047 }
3048
3049 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3050 return _monitoring_support->memory_pools();
3051 }
3052
3053 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3054 HeapRegion* region = heap_region_containing(start);
3055 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3056 }
3057
3058 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3059 // We can reach here with an active code cache marking cycle either because the
3060 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3061 // concurrent start young collection was below the threshold) or aborted. See
3062 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3063 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3064 // still have to arm all nmethod entry barriers. They are needed for adding oop
3065 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3066 if (!CodeCache::is_gc_marking_cycle_active()) {
3067 CodeCache::on_gc_marking_cycle_start();
3068 }
3069 if (concurrent_mark_start) {
3070 CodeCache::arm_all_nmethods();
3071 }
3072 }
3073
3074 void G1CollectedHeap::finish_codecache_marking_cycle() {
3075 CodeCache::on_gc_marking_cycle_finish();
3076 CodeCache::arm_all_nmethods();
3077 }