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/g1HeapRegionPrinter.hpp"
51 #include "gc/g1/g1HeapRegionRemSet.inline.hpp"
52 #include "gc/g1/g1HeapRegionSet.inline.hpp"
53 #include "gc/g1/g1HeapSizingPolicy.hpp"
54 #include "gc/g1/g1HeapTransition.hpp"
55 #include "gc/g1/g1HeapVerifier.hpp"
56 #include "gc/g1/g1InitLogger.hpp"
57 #include "gc/g1/g1MemoryPool.hpp"
58 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp"
59 #include "gc/g1/g1OopClosures.inline.hpp"
60 #include "gc/g1/g1ParallelCleaning.hpp"
61 #include "gc/g1/g1ParScanThreadState.inline.hpp"
62 #include "gc/g1/g1PeriodicGCTask.hpp"
63 #include "gc/g1/g1Policy.hpp"
64 #include "gc/g1/g1RedirtyCardsQueue.hpp"
65 #include "gc/g1/g1RegionPinCache.inline.hpp"
66 #include "gc/g1/g1RegionToSpaceMapper.hpp"
67 #include "gc/g1/g1RemSet.hpp"
68 #include "gc/g1/g1RootClosures.hpp"
69 #include "gc/g1/g1RootProcessor.hpp"
70 #include "gc/g1/g1SATBMarkQueueSet.hpp"
71 #include "gc/g1/g1ServiceThread.hpp"
72 #include "gc/g1/g1ThreadLocalData.hpp"
73 #include "gc/g1/g1Trace.hpp"
74 #include "gc/g1/g1UncommitRegionTask.hpp"
75 #include "gc/g1/g1VMOperations.hpp"
76 #include "gc/g1/g1YoungCollector.hpp"
77 #include "gc/g1/g1YoungGCAllocationFailureInjector.hpp"
78 #include "gc/shared/classUnloadingContext.hpp"
79 #include "gc/shared/concurrentGCBreakpoints.hpp"
80 #include "gc/shared/gcBehaviours.hpp"
81 #include "gc/shared/gcHeapSummary.hpp"
82 #include "gc/shared/gcId.hpp"
83 #include "gc/shared/gcTimer.hpp"
84 #include "gc/shared/gcTraceTime.inline.hpp"
85 #include "gc/shared/isGCActiveMark.hpp"
86 #include "gc/shared/locationPrinter.inline.hpp"
87 #include "gc/shared/oopStorageParState.hpp"
88 #include "gc/shared/referenceProcessor.inline.hpp"
89 #include "gc/shared/slidingForwarding.hpp"
90 #include "gc/shared/suspendibleThreadSet.hpp"
91 #include "gc/shared/taskqueue.inline.hpp"
92 #include "gc/shared/taskTerminator.hpp"
93 #include "gc/shared/tlab_globals.hpp"
94 #include "gc/shared/workerPolicy.hpp"
95 #include "gc/shared/weakProcessor.inline.hpp"
96 #include "logging/log.hpp"
97 #include "memory/allocation.hpp"
98 #include "memory/heapInspection.hpp"
99 #include "memory/iterator.hpp"
100 #include "memory/metaspaceUtils.hpp"
101 #include "memory/resourceArea.hpp"
102 #include "memory/universe.hpp"
103 #include "oops/access.inline.hpp"
104 #include "oops/compressedOops.inline.hpp"
105 #include "oops/oop.inline.hpp"
106 #include "runtime/atomic.hpp"
107 #include "runtime/cpuTimeCounters.hpp"
108 #include "runtime/handles.inline.hpp"
109 #include "runtime/init.hpp"
110 #include "runtime/java.hpp"
111 #include "runtime/orderAccess.hpp"
112 #include "runtime/threadSMR.hpp"
113 #include "runtime/vmThread.hpp"
114 #include "utilities/align.hpp"
115 #include "utilities/autoRestore.hpp"
116 #include "utilities/bitMap.inline.hpp"
117 #include "utilities/globalDefinitions.hpp"
118 #include "utilities/stack.inline.hpp"
119
120 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
121
122 // INVARIANTS/NOTES
123 //
124 // All allocation activity covered by the G1CollectedHeap interface is
125 // serialized by acquiring the HeapLock. This happens in mem_allocate
126 // and allocate_new_tlab, which are the "entry" points to the
127 // allocation code from the rest of the JVM. (Note that this does not
128 // apply to TLAB allocation, which is not part of this interface: it
129 // is done by clients of this interface.)
130
131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
132 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
133 }
134
135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
136 // The from card cache is not the memory that is actually committed. So we cannot
137 // take advantage of the zero_filled parameter.
138 reset_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
142 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
143 cl->set_max_workers(num_workers);
144 workers()->run_task(cl, num_workers);
145 }
146
147 uint G1CollectedHeap::get_chunks_per_region() {
148 uint log_region_size = G1HeapRegion::LogOfHRGrainBytes;
149 // Limit the expected input values to current known possible values of the
150 // (log) region size. Adjust as necessary after testing if changing the permissible
151 // values for region size.
152 assert(log_region_size >= 20 && log_region_size <= 29,
153 "expected value in [20,29], but got %u", log_region_size);
154 return 1u << (log_region_size / 2 - 4);
155 }
156
157 G1HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
158 MemRegion mr) {
159 return new G1HeapRegion(hrs_index, bot(), mr, &_card_set_config);
160 }
161
162 // Private methods.
163
164 G1HeapRegion* G1CollectedHeap::new_region(size_t word_size,
165 HeapRegionType type,
166 bool do_expand,
167 uint node_index) {
168 assert(!is_humongous(word_size) || word_size <= G1HeapRegion::GrainWords,
169 "the only time we use this to allocate a humongous region is "
170 "when we are allocating a single humongous region");
171
172 G1HeapRegion* res = _hrm.allocate_free_region(type, node_index);
173
174 if (res == nullptr && do_expand) {
175 // Currently, only attempts to allocate GC alloc regions set
176 // do_expand to true. So, we should only reach here during a
177 // safepoint.
178 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
179
180 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
181 word_size * HeapWordSize);
182
183 assert(word_size * HeapWordSize < G1HeapRegion::GrainBytes,
184 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
185 word_size * HeapWordSize);
186 if (expand_single_region(node_index)) {
187 // Given that expand_single_region() succeeded in expanding the heap, and we
188 // always expand the heap by an amount aligned to the heap
189 // region size, the free list should in theory not be empty.
190 // In either case allocate_free_region() will check for null.
191 res = _hrm.allocate_free_region(type, node_index);
192 }
193 }
194 return res;
195 }
196
197 void G1CollectedHeap::set_humongous_metadata(G1HeapRegion* first_hr,
198 uint num_regions,
199 size_t word_size,
200 bool update_remsets) {
201 // Calculate the new top of the humongous object.
202 HeapWord* obj_top = first_hr->bottom() + word_size;
203 // The word size sum of all the regions used
204 size_t word_size_sum = num_regions * G1HeapRegion::GrainWords;
205 assert(word_size <= word_size_sum, "sanity");
206
207 // How many words memory we "waste" which cannot hold a filler object.
208 size_t words_not_fillable = 0;
209
210 // Pad out the unused tail of the last region with filler
211 // objects, for improved usage accounting.
212
213 // How many words can we use for filler objects.
214 size_t words_fillable = word_size_sum - word_size;
215
216 if (words_fillable >= G1CollectedHeap::min_fill_size()) {
217 G1CollectedHeap::fill_with_objects(obj_top, words_fillable);
218 } else {
219 // We have space to fill, but we cannot fit an object there.
220 words_not_fillable = words_fillable;
221 words_fillable = 0;
222 }
223
224 // We will set up the first region as "starts humongous". This
225 // will also update the BOT covering all the regions to reflect
226 // that there is a single object that starts at the bottom of the
227 // first region.
228 first_hr->hr_clear(false /* clear_space */);
229 first_hr->set_starts_humongous(obj_top, words_fillable);
230
231 if (update_remsets) {
232 _policy->remset_tracker()->update_at_allocate(first_hr);
233 }
234
235 // Indices of first and last regions in the series.
236 uint first = first_hr->hrm_index();
237 uint last = first + num_regions - 1;
238
239 G1HeapRegion* hr = nullptr;
240 for (uint i = first + 1; i <= last; ++i) {
241 hr = region_at(i);
242 hr->hr_clear(false /* clear_space */);
243 hr->set_continues_humongous(first_hr);
244 if (update_remsets) {
245 _policy->remset_tracker()->update_at_allocate(hr);
246 }
247 }
248
249 // Up to this point no concurrent thread would have been able to
250 // do any scanning on any region in this series. All the top
251 // fields still point to bottom, so the intersection between
252 // [bottom,top] and [card_start,card_end] will be empty. Before we
253 // update the top fields, we'll do a storestore to make sure that
254 // no thread sees the update to top before the zeroing of the
255 // object header and the BOT initialization.
256 OrderAccess::storestore();
257
258 // Now, we will update the top fields of the "continues humongous"
259 // regions except the last one.
260 for (uint i = first; i < last; ++i) {
261 hr = region_at(i);
262 hr->set_top(hr->end());
263 }
264
265 hr = region_at(last);
266 // If we cannot fit a filler object, we must set top to the end
267 // of the humongous object, otherwise we cannot iterate the heap
268 // and the BOT will not be complete.
269 hr->set_top(hr->end() - words_not_fillable);
270
271 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
272 "obj_top should be in last region");
273
274 assert(words_not_fillable == 0 ||
275 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
276 "Miscalculation in humongous allocation");
277 }
278
279 HeapWord*
280 G1CollectedHeap::humongous_obj_allocate_initialize_regions(G1HeapRegion* first_hr,
281 uint num_regions,
282 size_t word_size) {
283 assert(first_hr != nullptr, "pre-condition");
284 assert(is_humongous(word_size), "word_size should be humongous");
285 assert(num_regions * G1HeapRegion::GrainWords >= word_size, "pre-condition");
286
287 // Index of last region in the series.
288 uint first = first_hr->hrm_index();
289 uint last = first + num_regions - 1;
290
291 // We need to initialize the region(s) we just discovered. This is
292 // a bit tricky given that it can happen concurrently with
293 // refinement threads refining cards on these regions and
294 // potentially wanting to refine the BOT as they are scanning
295 // those cards (this can happen shortly after a cleanup; see CR
296 // 6991377). So we have to set up the region(s) carefully and in
297 // a specific order.
298
299 // The passed in hr will be the "starts humongous" region. The header
300 // of the new object will be placed at the bottom of this region.
301 HeapWord* new_obj = first_hr->bottom();
302
303 // First, we need to zero the header of the space that we will be
304 // allocating. When we update top further down, some refinement
305 // threads might try to scan the region. By zeroing the header we
306 // ensure that any thread that will try to scan the region will
307 // come across the zero klass word and bail out.
308 //
309 // NOTE: It would not have been correct to have used
310 // CollectedHeap::fill_with_object() and make the space look like
311 // an int array. The thread that is doing the allocation will
312 // later update the object header to a potentially different array
313 // type and, for a very short period of time, the klass and length
314 // fields will be inconsistent. This could cause a refinement
315 // thread to calculate the object size incorrectly.
316 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
317
318 // Next, update the metadata for the regions.
319 set_humongous_metadata(first_hr, num_regions, word_size, true);
320
321 G1HeapRegion* last_hr = region_at(last);
322 size_t used = byte_size(first_hr->bottom(), last_hr->top());
323
324 increase_used(used);
325
326 for (uint i = first; i <= last; ++i) {
327 G1HeapRegion *hr = region_at(i);
328 _humongous_set.add(hr);
329 G1HeapRegionPrinter::alloc(hr);
330 }
331
332 return new_obj;
333 }
334
335 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
336 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
337 return align_up(word_size, G1HeapRegion::GrainWords) / G1HeapRegion::GrainWords;
338 }
339
340 // If could fit into free regions w/o expansion, try.
341 // Otherwise, if can expand, do so.
342 // Otherwise, if using ex regions might help, try with ex given back.
343 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
344 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
345
346 _verifier->verify_region_sets_optional();
347
348 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
349
350 // Policy: First try to allocate a humongous object in the free list.
351 G1HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
352 if (humongous_start == nullptr) {
353 // Policy: We could not find enough regions for the humongous object in the
354 // free list. Look through the heap to find a mix of free and uncommitted regions.
355 // If so, expand the heap and allocate the humongous object.
356 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
357 if (humongous_start != nullptr) {
358 // We managed to find a region by expanding the heap.
359 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
360 word_size * HeapWordSize);
361 policy()->record_new_heap_size(num_regions());
362 } else {
363 // Policy: Potentially trigger a defragmentation GC.
364 }
365 }
366
367 HeapWord* result = nullptr;
368 if (humongous_start != nullptr) {
369 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
370 assert(result != nullptr, "it should always return a valid result");
371
372 // A successful humongous object allocation changes the used space
373 // information of the old generation so we need to recalculate the
374 // sizes and update the jstat counters here.
375 monitoring_support()->update_sizes();
376 }
377
378 _verifier->verify_region_sets_optional();
379
380 return result;
381 }
382
383 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
384 size_t requested_size,
385 size_t* actual_size) {
386 assert_heap_not_locked_and_not_at_safepoint();
387 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
388
389 return attempt_allocation(min_size, requested_size, actual_size);
390 }
391
392 HeapWord*
393 G1CollectedHeap::mem_allocate(size_t word_size,
394 bool* gc_overhead_limit_was_exceeded) {
395 assert_heap_not_locked_and_not_at_safepoint();
396
397 if (is_humongous(word_size)) {
398 return attempt_allocation_humongous(word_size);
399 }
400 size_t dummy = 0;
401 return attempt_allocation(word_size, word_size, &dummy);
402 }
403
404 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
405 ResourceMark rm; // For retrieving the thread names in log messages.
406
407 // Make sure you read the note in attempt_allocation_humongous().
408
409 assert_heap_not_locked_and_not_at_safepoint();
410 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
411 "be called for humongous allocation requests");
412
413 // We should only get here after the first-level allocation attempt
414 // (attempt_allocation()) failed to allocate.
415
416 // We will loop until a) we manage to successfully perform the allocation or b)
417 // successfully schedule a collection which fails to perform the allocation.
418 // Case b) is the only case when we'll return null.
419 HeapWord* result = nullptr;
420 for (uint try_count = 1; /* we'll return */; try_count++) {
421 uint gc_count_before;
422
423 {
424 MutexLocker x(Heap_lock);
425
426 // Now that we have the lock, we first retry the allocation in case another
427 // thread changed the region while we were waiting to acquire the lock.
428 result = _allocator->attempt_allocation_locked(word_size);
429 if (result != nullptr) {
430 return result;
431 }
432
433 // Read the GC count while still holding the Heap_lock.
434 gc_count_before = total_collections();
435 }
436
437 bool succeeded;
438 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
439 if (succeeded) {
440 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
441 Thread::current()->name(), p2i(result));
442 return result;
443 }
444
445 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
446 Thread::current()->name(), word_size);
447
448 // We can reach here if we were unsuccessful in scheduling a collection (because
449 // another thread beat us to it). In this case immeditealy retry the allocation
450 // attempt because another thread successfully performed a collection and possibly
451 // reclaimed enough space. The first attempt (without holding the Heap_lock) is
452 // here and the follow-on attempt will be at the start of the next loop
453 // iteration (after taking the Heap_lock).
454 size_t dummy = 0;
455 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
456 if (result != nullptr) {
457 return result;
458 }
459
460 // Give a warning if we seem to be looping forever.
461 if ((QueuedAllocationWarningCount > 0) &&
462 (try_count % QueuedAllocationWarningCount == 0)) {
463 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
464 Thread::current()->name(), try_count, word_size);
465 }
466 }
467
468 ShouldNotReachHere();
469 return nullptr;
470 }
471
472 template <typename Func>
473 void G1CollectedHeap::iterate_regions_in_range(MemRegion range, const Func& func) {
474 // Mark each G1 region touched by the range as old, add it to
475 // the old set, and set top.
476 G1HeapRegion* curr_region = _hrm.addr_to_region(range.start());
477 G1HeapRegion* end_region = _hrm.addr_to_region(range.last());
478
479 while (curr_region != nullptr) {
480 bool is_last = curr_region == end_region;
481 G1HeapRegion* next_region = is_last ? nullptr : _hrm.next_region_in_heap(curr_region);
482
483 func(curr_region, is_last);
484
485 curr_region = next_region;
486 }
487 }
488
489 HeapWord* G1CollectedHeap::alloc_archive_region(size_t word_size, HeapWord* preferred_addr) {
490 assert(!is_init_completed(), "Expect to be called at JVM init time");
491 MutexLocker x(Heap_lock);
492
493 MemRegion reserved = _hrm.reserved();
494
495 if (reserved.word_size() <= word_size) {
496 log_info(gc, heap)("Unable to allocate regions as archive heap is too large; size requested = " SIZE_FORMAT
497 " bytes, heap = " SIZE_FORMAT " bytes", word_size, reserved.word_size());
498 return nullptr;
499 }
500
501 // Temporarily disable pretouching of heap pages. This interface is used
502 // when mmap'ing archived heap data in, so pre-touching is wasted.
503 FlagSetting fs(AlwaysPreTouch, false);
504
505 size_t commits = 0;
506 // Attempt to allocate towards the end of the heap.
507 HeapWord* start_addr = reserved.end() - align_up(word_size, G1HeapRegion::GrainWords);
508 MemRegion range = MemRegion(start_addr, word_size);
509 HeapWord* last_address = range.last();
510 if (!_hrm.allocate_containing_regions(range, &commits, workers())) {
511 return nullptr;
512 }
513 increase_used(word_size * HeapWordSize);
514 if (commits != 0) {
515 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
516 G1HeapRegion::GrainWords * HeapWordSize * commits);
517 }
518
519 // Mark each G1 region touched by the range as old, add it to
520 // the old set, and set top.
521 auto set_region_to_old = [&] (G1HeapRegion* r, bool is_last) {
522 assert(r->is_empty(), "Region already in use (%u)", r->hrm_index());
523
524 HeapWord* top = is_last ? last_address + 1 : r->end();
525 r->set_top(top);
526
527 r->set_old();
528 G1HeapRegionPrinter::alloc(r);
529 _old_set.add(r);
530 };
531
532 iterate_regions_in_range(range, set_region_to_old);
533 return start_addr;
534 }
535
536 void G1CollectedHeap::populate_archive_regions_bot(MemRegion range) {
537 assert(!is_init_completed(), "Expect to be called at JVM init time");
538
539 iterate_regions_in_range(range,
540 [&] (G1HeapRegion* r, bool is_last) {
541 r->update_bot();
542 });
543 }
544
545 void G1CollectedHeap::dealloc_archive_regions(MemRegion range) {
546 assert(!is_init_completed(), "Expect to be called at JVM init time");
547 MemRegion reserved = _hrm.reserved();
548 size_t size_used = 0;
549 uint shrink_count = 0;
550
551 // Free the G1 regions that are within the specified range.
552 MutexLocker x(Heap_lock);
553 HeapWord* start_address = range.start();
554 HeapWord* last_address = range.last();
555
556 assert(reserved.contains(start_address) && reserved.contains(last_address),
557 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
558 p2i(start_address), p2i(last_address));
559 size_used += range.byte_size();
560
561 // Free, empty and uncommit regions with CDS archive content.
562 auto dealloc_archive_region = [&] (G1HeapRegion* r, bool is_last) {
563 guarantee(r->is_old(), "Expected old region at index %u", r->hrm_index());
564 _old_set.remove(r);
565 r->set_free();
566 r->set_top(r->bottom());
567 _hrm.shrink_at(r->hrm_index(), 1);
568 shrink_count++;
569 };
570
571 iterate_regions_in_range(range, dealloc_archive_region);
572
573 if (shrink_count != 0) {
574 log_debug(gc, ergo, heap)("Attempt heap shrinking (CDS archive regions). Total size: " SIZE_FORMAT "B",
575 G1HeapRegion::GrainWords * HeapWordSize * shrink_count);
576 // Explicit uncommit.
577 uncommit_regions(shrink_count);
578 }
579 decrease_used(size_used);
580 }
581
582 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
583 size_t desired_word_size,
584 size_t* actual_word_size) {
585 assert_heap_not_locked_and_not_at_safepoint();
586 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
587 "be called for humongous allocation requests");
588
589 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
590
591 if (result == nullptr) {
592 *actual_word_size = desired_word_size;
593 result = attempt_allocation_slow(desired_word_size);
594 }
595
596 assert_heap_not_locked();
597 if (result != nullptr) {
598 assert(*actual_word_size != 0, "Actual size must have been set here");
599 dirty_young_block(result, *actual_word_size);
600 } else {
601 *actual_word_size = 0;
602 }
603
604 return result;
605 }
606
607 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
608 ResourceMark rm; // For retrieving the thread names in log messages.
609
610 // The structure of this method has a lot of similarities to
611 // attempt_allocation_slow(). The reason these two were not merged
612 // into a single one is that such a method would require several "if
613 // allocation is not humongous do this, otherwise do that"
614 // conditional paths which would obscure its flow. In fact, an early
615 // version of this code did use a unified method which was harder to
616 // follow and, as a result, it had subtle bugs that were hard to
617 // track down. So keeping these two methods separate allows each to
618 // be more readable. It will be good to keep these two in sync as
619 // much as possible.
620
621 assert_heap_not_locked_and_not_at_safepoint();
622 assert(is_humongous(word_size), "attempt_allocation_humongous() "
623 "should only be called for humongous allocations");
624
625 // Humongous objects can exhaust the heap quickly, so we should check if we
626 // need to start a marking cycle at each humongous object allocation. We do
627 // the check before we do the actual allocation. The reason for doing it
628 // before the allocation is that we avoid having to keep track of the newly
629 // allocated memory while we do a GC.
630 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
631 word_size)) {
632 collect(GCCause::_g1_humongous_allocation);
633 }
634
635 // We will loop until a) we manage to successfully perform the allocation or b)
636 // successfully schedule a collection which fails to perform the allocation.
637 // Case b) is the only case when we'll return null.
638 HeapWord* result = nullptr;
639 for (uint try_count = 1; /* we'll return */; try_count++) {
640 uint gc_count_before;
641
642
643 {
644 MutexLocker x(Heap_lock);
645
646 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
647 // Given that humongous objects are not allocated in young
648 // regions, we'll first try to do the allocation without doing a
649 // collection hoping that there's enough space in the heap.
650 result = humongous_obj_allocate(word_size);
651 if (result != nullptr) {
652 policy()->old_gen_alloc_tracker()->
653 add_allocated_humongous_bytes_since_last_gc(size_in_regions * G1HeapRegion::GrainBytes);
654 return result;
655 }
656
657 // Read the GC count while still holding the Heap_lock.
658 gc_count_before = total_collections();
659 }
660
661 bool succeeded;
662 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
663 if (succeeded) {
664 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
665 Thread::current()->name(), p2i(result));
666 if (result != nullptr) {
667 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
668 policy()->old_gen_alloc_tracker()->
669 record_collection_pause_humongous_allocation(size_in_regions * G1HeapRegion::GrainBytes);
670 }
671 return result;
672 }
673
674 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
675 Thread::current()->name(), word_size);
676
677 // We can reach here if we were unsuccessful in scheduling a collection (because
678 // another thread beat us to it).
679 // Humongous object allocation always needs a lock, so we wait for the retry
680 // in the next iteration of the loop, unlike for the regular iteration case.
681 // Give a warning if we seem to be looping forever.
682
683 if ((QueuedAllocationWarningCount > 0) &&
684 (try_count % QueuedAllocationWarningCount == 0)) {
685 log_warning(gc, alloc)("%s: Retried allocation %u times for %zu words",
686 Thread::current()->name(), try_count, word_size);
687 }
688 }
689
690 ShouldNotReachHere();
691 return nullptr;
692 }
693
694 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
695 bool expect_null_mutator_alloc_region) {
696 assert_at_safepoint_on_vm_thread();
697 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
698 "the current alloc region was unexpectedly found to be non-null");
699
700 if (!is_humongous(word_size)) {
701 return _allocator->attempt_allocation_locked(word_size);
702 } else {
703 HeapWord* result = humongous_obj_allocate(word_size);
704 if (result != nullptr && policy()->need_to_start_conc_mark("STW humongous allocation")) {
705 collector_state()->set_initiate_conc_mark_if_possible(true);
706 }
707 return result;
708 }
709
710 ShouldNotReachHere();
711 }
712
713 class PostCompactionPrinterClosure: public HeapRegionClosure {
714 public:
715 bool do_heap_region(G1HeapRegion* hr) {
716 assert(!hr->is_young(), "not expecting to find young regions");
717 G1HeapRegionPrinter::post_compaction(hr);
718 return false;
719 }
720 };
721
722 void G1CollectedHeap::print_heap_after_full_collection() {
723 // Post collection region logging.
724 // We should do this after we potentially resize the heap so
725 // that all the COMMIT / UNCOMMIT events are generated before
726 // the compaction events.
727 if (G1HeapRegionPrinter::is_active()) {
728 PostCompactionPrinterClosure cl;
729 heap_region_iterate(&cl);
730 }
731 }
732
733 bool G1CollectedHeap::abort_concurrent_cycle() {
734 // Disable discovery and empty the discovered lists
735 // for the CM ref processor.
736 _ref_processor_cm->disable_discovery();
737 _ref_processor_cm->abandon_partial_discovery();
738 _ref_processor_cm->verify_no_references_recorded();
739
740 // Abandon current iterations of concurrent marking and concurrent
741 // refinement, if any are in progress.
742 return concurrent_mark()->concurrent_cycle_abort();
743 }
744
745 void G1CollectedHeap::prepare_heap_for_full_collection() {
746 // Make sure we'll choose a new allocation region afterwards.
747 _allocator->release_mutator_alloc_regions();
748 _allocator->abandon_gc_alloc_regions();
749
750 // We may have added regions to the current incremental collection
751 // set between the last GC or pause and now. We need to clear the
752 // incremental collection set and then start rebuilding it afresh
753 // after this full GC.
754 abandon_collection_set(collection_set());
755
756 _hrm.remove_all_free_regions();
757 }
758
759 void G1CollectedHeap::verify_before_full_collection() {
760 assert_used_and_recalculate_used_equal(this);
761 if (!VerifyBeforeGC) {
762 return;
763 }
764 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
765 return;
766 }
767 _verifier->verify_region_sets_optional();
768 _verifier->verify_before_gc();
769 _verifier->verify_bitmap_clear(true /* above_tams_only */);
770 }
771
772 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
773 // Prepare heap for normal collections.
774 assert(num_free_regions() == 0, "we should not have added any free regions");
775 rebuild_region_sets(false /* free_list_only */);
776 abort_refinement();
777 resize_heap_if_necessary();
778 uncommit_regions_if_necessary();
779
780 // Rebuild the code root lists for each region
781 rebuild_code_roots();
782
783 start_new_collection_set();
784 _allocator->init_mutator_alloc_regions();
785
786 // Post collection state updates.
787 MetaspaceGC::compute_new_size();
788 }
789
790 void G1CollectedHeap::abort_refinement() {
791 // Discard all remembered set updates and reset refinement statistics.
792 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
793 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
794 "DCQS should be empty");
795 concurrent_refine()->get_and_reset_refinement_stats();
796 }
797
798 void G1CollectedHeap::verify_after_full_collection() {
799 if (!VerifyAfterGC) {
800 return;
801 }
802 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
803 return;
804 }
805 _hrm.verify_optional();
806 _verifier->verify_region_sets_optional();
807 _verifier->verify_after_gc();
808 _verifier->verify_bitmap_clear(false /* above_tams_only */);
809
810 // At this point there should be no regions in the
811 // entire heap tagged as young.
812 assert(check_young_list_empty(), "young list should be empty at this point");
813
814 // Note: since we've just done a full GC, concurrent
815 // marking is no longer active. Therefore we need not
816 // re-enable reference discovery for the CM ref processor.
817 // That will be done at the start of the next marking cycle.
818 // We also know that the STW processor should no longer
819 // discover any new references.
820 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
821 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
822 _ref_processor_stw->verify_no_references_recorded();
823 _ref_processor_cm->verify_no_references_recorded();
824 }
825
826 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs,
827 bool do_maximal_compaction) {
828 assert_at_safepoint_on_vm_thread();
829
830 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
831 soft_ref_policy()->should_clear_all_soft_refs();
832
833 G1FullGCMark gc_mark;
834 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true);
835 G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
836
837 collector.prepare_collection();
838 collector.collect();
839 collector.complete_collection();
840
841 // Full collection was successfully completed.
842 return true;
843 }
844
845 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
846 // Currently, there is no facility in the do_full_collection(bool) API to notify
847 // the caller that the collection did not succeed (e.g., because it was locked
848 // out by the GC locker). So, right now, we'll ignore the return value.
849
850 do_full_collection(clear_all_soft_refs,
851 false /* do_maximal_compaction */);
852 }
853
854 bool G1CollectedHeap::upgrade_to_full_collection() {
855 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
856 log_info(gc, ergo)("Attempting full compaction clearing soft references");
857 bool success = do_full_collection(true /* clear_all_soft_refs */,
858 false /* do_maximal_compaction */);
859 // do_full_collection only fails if blocked by GC locker and that can't
860 // be the case here since we only call this when already completed one gc.
861 assert(success, "invariant");
862 return success;
863 }
864
865 void G1CollectedHeap::resize_heap_if_necessary() {
866 assert_at_safepoint_on_vm_thread();
867
868 bool should_expand;
869 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
870
871 if (resize_amount == 0) {
872 return;
873 } else if (should_expand) {
874 expand(resize_amount, _workers);
875 } else {
876 shrink(resize_amount);
877 }
878 }
879
880 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
881 bool do_gc,
882 bool maximal_compaction,
883 bool expect_null_mutator_alloc_region,
884 bool* gc_succeeded) {
885 *gc_succeeded = true;
886 // Let's attempt the allocation first.
887 HeapWord* result =
888 attempt_allocation_at_safepoint(word_size,
889 expect_null_mutator_alloc_region);
890 if (result != nullptr) {
891 return result;
892 }
893
894 // In a G1 heap, we're supposed to keep allocation from failing by
895 // incremental pauses. Therefore, at least for now, we'll favor
896 // expansion over collection. (This might change in the future if we can
897 // do something smarter than full collection to satisfy a failed alloc.)
898 result = expand_and_allocate(word_size);
899 if (result != nullptr) {
900 return result;
901 }
902
903 if (do_gc) {
904 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
905 // Expansion didn't work, we'll try to do a Full GC.
906 // If maximal_compaction is set we clear all soft references and don't
907 // allow any dead wood to be left on the heap.
908 if (maximal_compaction) {
909 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
910 } else {
911 log_info(gc, ergo)("Attempting full compaction");
912 }
913 *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ ,
914 maximal_compaction /* do_maximal_compaction */);
915 }
916
917 return nullptr;
918 }
919
920 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
921 bool* succeeded) {
922 assert_at_safepoint_on_vm_thread();
923
924 // Attempts to allocate followed by Full GC.
925 HeapWord* result =
926 satisfy_failed_allocation_helper(word_size,
927 true, /* do_gc */
928 false, /* maximum_collection */
929 false, /* expect_null_mutator_alloc_region */
930 succeeded);
931
932 if (result != nullptr || !*succeeded) {
933 return result;
934 }
935
936 // Attempts to allocate followed by Full GC that will collect all soft references.
937 result = satisfy_failed_allocation_helper(word_size,
938 true, /* do_gc */
939 true, /* maximum_collection */
940 true, /* expect_null_mutator_alloc_region */
941 succeeded);
942
943 if (result != nullptr || !*succeeded) {
944 return result;
945 }
946
947 // Attempts to allocate, no GC
948 result = satisfy_failed_allocation_helper(word_size,
949 false, /* do_gc */
950 false, /* maximum_collection */
951 true, /* expect_null_mutator_alloc_region */
952 succeeded);
953
954 if (result != nullptr) {
955 return result;
956 }
957
958 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
959 "Flag should have been handled and cleared prior to this point");
960
961 // What else? We might try synchronous finalization later. If the total
962 // space available is large enough for the allocation, then a more
963 // complete compaction phase than we've tried so far might be
964 // appropriate.
965 return nullptr;
966 }
967
968 // Attempting to expand the heap sufficiently
969 // to support an allocation of the given "word_size". If
970 // successful, perform the allocation and return the address of the
971 // allocated block, or else null.
972
973 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
974 assert_at_safepoint_on_vm_thread();
975
976 _verifier->verify_region_sets_optional();
977
978 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
979 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
980 word_size * HeapWordSize);
981
982
983 if (expand(expand_bytes, _workers)) {
984 _hrm.verify_optional();
985 _verifier->verify_region_sets_optional();
986 return attempt_allocation_at_safepoint(word_size,
987 false /* expect_null_mutator_alloc_region */);
988 }
989 return nullptr;
990 }
991
992 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
993 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
994 aligned_expand_bytes = align_up(aligned_expand_bytes, G1HeapRegion::GrainBytes);
995
996 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
997 expand_bytes, aligned_expand_bytes);
998
999 if (is_maximal_no_gc()) {
1000 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1001 return false;
1002 }
1003
1004 double expand_heap_start_time_sec = os::elapsedTime();
1005 uint regions_to_expand = (uint)(aligned_expand_bytes / G1HeapRegion::GrainBytes);
1006 assert(regions_to_expand > 0, "Must expand by at least one region");
1007
1008 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1009 if (expand_time_ms != nullptr) {
1010 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1011 }
1012
1013 assert(expanded_by > 0, "must have failed during commit.");
1014
1015 size_t actual_expand_bytes = expanded_by * G1HeapRegion::GrainBytes;
1016 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1017 policy()->record_new_heap_size(num_regions());
1018
1019 return true;
1020 }
1021
1022 bool G1CollectedHeap::expand_single_region(uint node_index) {
1023 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1024
1025 if (expanded_by == 0) {
1026 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1027 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1028 return false;
1029 }
1030
1031 policy()->record_new_heap_size(num_regions());
1032 return true;
1033 }
1034
1035 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1036 size_t aligned_shrink_bytes =
1037 ReservedSpace::page_align_size_down(shrink_bytes);
1038 aligned_shrink_bytes = align_down(aligned_shrink_bytes, G1HeapRegion::GrainBytes);
1039 uint num_regions_to_remove = (uint)(shrink_bytes / G1HeapRegion::GrainBytes);
1040
1041 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1042 size_t shrunk_bytes = num_regions_removed * G1HeapRegion::GrainBytes;
1043
1044 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",
1045 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1046 if (num_regions_removed > 0) {
1047 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1048 policy()->record_new_heap_size(num_regions());
1049 } else {
1050 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1051 }
1052 }
1053
1054 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1055 _verifier->verify_region_sets_optional();
1056
1057 // We should only reach here at the end of a Full GC or during Remark which
1058 // means we should not not be holding to any GC alloc regions. The method
1059 // below will make sure of that and do any remaining clean up.
1060 _allocator->abandon_gc_alloc_regions();
1061
1062 // Instead of tearing down / rebuilding the free lists here, we
1063 // could instead use the remove_all_pending() method on free_list to
1064 // remove only the ones that we need to remove.
1065 _hrm.remove_all_free_regions();
1066 shrink_helper(shrink_bytes);
1067 rebuild_region_sets(true /* free_list_only */);
1068
1069 _hrm.verify_optional();
1070 _verifier->verify_region_sets_optional();
1071 }
1072
1073 class OldRegionSetChecker : public HeapRegionSetChecker {
1074 public:
1075 void check_mt_safety() {
1076 // Master Old Set MT safety protocol:
1077 // (a) If we're at a safepoint, operations on the master old set
1078 // should be invoked:
1079 // - by the VM thread (which will serialize them), or
1080 // - by the GC workers while holding the FreeList_lock, if we're
1081 // at a safepoint for an evacuation pause (this lock is taken
1082 // anyway when an GC alloc region is retired so that a new one
1083 // is allocated from the free list), or
1084 // - by the GC workers while holding the OldSets_lock, if we're at a
1085 // safepoint for a cleanup pause.
1086 // (b) If we're not at a safepoint, operations on the master old set
1087 // should be invoked while holding the Heap_lock.
1088
1089 if (SafepointSynchronize::is_at_safepoint()) {
1090 guarantee(Thread::current()->is_VM_thread() ||
1091 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1092 "master old set MT safety protocol at a safepoint");
1093 } else {
1094 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1095 }
1096 }
1097 bool is_correct_type(G1HeapRegion* hr) { return hr->is_old(); }
1098 const char* get_description() { return "Old Regions"; }
1099 };
1100
1101 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1102 public:
1103 void check_mt_safety() {
1104 // Humongous Set MT safety protocol:
1105 // (a) If we're at a safepoint, operations on the master humongous
1106 // set should be invoked by either the VM thread (which will
1107 // serialize them) or by the GC workers while holding the
1108 // OldSets_lock.
1109 // (b) If we're not at a safepoint, operations on the master
1110 // humongous set should be invoked while holding the Heap_lock.
1111
1112 if (SafepointSynchronize::is_at_safepoint()) {
1113 guarantee(Thread::current()->is_VM_thread() ||
1114 OldSets_lock->owned_by_self(),
1115 "master humongous set MT safety protocol at a safepoint");
1116 } else {
1117 guarantee(Heap_lock->owned_by_self(),
1118 "master humongous set MT safety protocol outside a safepoint");
1119 }
1120 }
1121 bool is_correct_type(G1HeapRegion* hr) { return hr->is_humongous(); }
1122 const char* get_description() { return "Humongous Regions"; }
1123 };
1124
1125 G1CollectedHeap::G1CollectedHeap() :
1126 CollectedHeap(),
1127 _service_thread(nullptr),
1128 _periodic_gc_task(nullptr),
1129 _free_arena_memory_task(nullptr),
1130 _workers(nullptr),
1131 _card_table(nullptr),
1132 _collection_pause_end(Ticks::now()),
1133 _old_set("Old Region Set", new OldRegionSetChecker()),
1134 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1135 _bot(nullptr),
1136 _listener(),
1137 _numa(G1NUMA::create()),
1138 _hrm(),
1139 _allocator(nullptr),
1140 _allocation_failure_injector(),
1141 _verifier(nullptr),
1142 _summary_bytes_used(0),
1143 _bytes_used_during_gc(0),
1144 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1145 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1146 _monitoring_support(nullptr),
1147 _num_humongous_objects(0),
1148 _num_humongous_reclaim_candidates(0),
1149 _collector_state(),
1150 _old_marking_cycles_started(0),
1151 _old_marking_cycles_completed(0),
1152 _eden(),
1153 _survivor(),
1154 _gc_timer_stw(new STWGCTimer()),
1155 _gc_tracer_stw(new G1NewTracer()),
1156 _policy(new G1Policy(_gc_timer_stw)),
1157 _heap_sizing_policy(nullptr),
1158 _collection_set(this, _policy),
1159 _rem_set(nullptr),
1160 _card_set_config(),
1161 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1162 _cm(nullptr),
1163 _cm_thread(nullptr),
1164 _cr(nullptr),
1165 _task_queues(nullptr),
1166 _ref_processor_stw(nullptr),
1167 _is_alive_closure_stw(this),
1168 _is_subject_to_discovery_stw(this),
1169 _ref_processor_cm(nullptr),
1170 _is_alive_closure_cm(),
1171 _is_subject_to_discovery_cm(this),
1172 _region_attr() {
1173
1174 _verifier = new G1HeapVerifier(this);
1175
1176 _allocator = new G1Allocator(this);
1177
1178 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1179
1180 _humongous_object_threshold_in_words = humongous_threshold_for(G1HeapRegion::GrainWords);
1181
1182 // Since filler arrays are never referenced, we can make them region sized.
1183 // This simplifies filling up the region in case we have some potentially
1184 // unreferenced (by Java code, but still in use by native code) pinned objects
1185 // in there.
1186 _filler_array_max_size = G1HeapRegion::GrainWords;
1187
1188 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1189 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1190
1191 uint n_queues = ParallelGCThreads;
1192 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1193
1194 for (uint i = 0; i < n_queues; i++) {
1195 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1196 _task_queues->register_queue(i, q);
1197 }
1198
1199 _gc_tracer_stw->initialize();
1200
1201 guarantee(_task_queues != nullptr, "task_queues allocation failure.");
1202 }
1203
1204 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1205 size_t size,
1206 size_t translation_factor) {
1207 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1208 // Allocate a new reserved space, preferring to use large pages.
1209 ReservedSpace rs(size, preferred_page_size);
1210 size_t page_size = rs.page_size();
1211 G1RegionToSpaceMapper* result =
1212 G1RegionToSpaceMapper::create_mapper(rs,
1213 size,
1214 page_size,
1215 G1HeapRegion::GrainBytes,
1216 translation_factor,
1217 mtGC);
1218
1219 os::trace_page_sizes_for_requested_size(description,
1220 size,
1221 preferred_page_size,
1222 rs.base(),
1223 rs.size(),
1224 page_size);
1225
1226 return result;
1227 }
1228
1229 jint G1CollectedHeap::initialize_concurrent_refinement() {
1230 jint ecode = JNI_OK;
1231 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1232 return ecode;
1233 }
1234
1235 jint G1CollectedHeap::initialize_service_thread() {
1236 _service_thread = new G1ServiceThread();
1237 if (_service_thread->osthread() == nullptr) {
1238 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1239 return JNI_ENOMEM;
1240 }
1241 return JNI_OK;
1242 }
1243
1244 jint G1CollectedHeap::initialize() {
1245
1246 // Necessary to satisfy locking discipline assertions.
1247
1248 MutexLocker x(Heap_lock);
1249
1250 // While there are no constraints in the GC code that HeapWordSize
1251 // be any particular value, there are multiple other areas in the
1252 // system which believe this to be true (e.g. oop->object_size in some
1253 // cases incorrectly returns the size in wordSize units rather than
1254 // HeapWordSize).
1255 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1256
1257 size_t init_byte_size = InitialHeapSize;
1258 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1259
1260 // Ensure that the sizes are properly aligned.
1261 Universe::check_alignment(init_byte_size, G1HeapRegion::GrainBytes, "g1 heap");
1262 Universe::check_alignment(reserved_byte_size, G1HeapRegion::GrainBytes, "g1 heap");
1263 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1264
1265 // Reserve the maximum.
1266
1267 // When compressed oops are enabled, the preferred heap base
1268 // is calculated by subtracting the requested size from the
1269 // 32Gb boundary and using the result as the base address for
1270 // heap reservation. If the requested size is not aligned to
1271 // G1HeapRegion::GrainBytes (i.e. the alignment that is passed
1272 // into the ReservedHeapSpace constructor) then the actual
1273 // base of the reserved heap may end up differing from the
1274 // address that was requested (i.e. the preferred heap base).
1275 // If this happens then we could end up using a non-optimal
1276 // compressed oops mode.
1277
1278 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1279 HeapAlignment);
1280
1281 initialize_reserved_region(heap_rs);
1282
1283 // Create the barrier set for the entire reserved region.
1284 G1CardTable* ct = new G1CardTable(heap_rs.region());
1285 G1BarrierSet* bs = new G1BarrierSet(ct);
1286 bs->initialize();
1287 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1288 BarrierSet::set_barrier_set(bs);
1289 _card_table = ct;
1290
1291 {
1292 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1293 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1294 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1295 }
1296
1297 // Create space mappers.
1298 size_t page_size = heap_rs.page_size();
1299 G1RegionToSpaceMapper* heap_storage =
1300 G1RegionToSpaceMapper::create_mapper(heap_rs,
1301 heap_rs.size(),
1302 page_size,
1303 G1HeapRegion::GrainBytes,
1304 1,
1305 mtJavaHeap);
1306 if(heap_storage == nullptr) {
1307 vm_shutdown_during_initialization("Could not initialize G1 heap");
1308 return JNI_ERR;
1309 }
1310
1311 os::trace_page_sizes("Heap",
1312 MinHeapSize,
1313 reserved_byte_size,
1314 heap_rs.base(),
1315 heap_rs.size(),
1316 page_size);
1317 heap_storage->set_mapping_changed_listener(&_listener);
1318
1319 // Create storage for the BOT, card table and the bitmap.
1320 G1RegionToSpaceMapper* bot_storage =
1321 create_aux_memory_mapper("Block Offset Table",
1322 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1323 G1BlockOffsetTable::heap_map_factor());
1324
1325 G1RegionToSpaceMapper* cardtable_storage =
1326 create_aux_memory_mapper("Card Table",
1327 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1328 G1CardTable::heap_map_factor());
1329
1330 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1331 G1RegionToSpaceMapper* bitmap_storage =
1332 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1333
1334 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1335 _card_table->initialize(cardtable_storage);
1336
1337 // 6843694 - ensure that the maximum region index can fit
1338 // in the remembered set structures.
1339 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1340 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1341
1342 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1343 // start within the first card.
1344 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1345 G1FromCardCache::initialize(max_reserved_regions());
1346 // Also create a G1 rem set.
1347 _rem_set = new G1RemSet(this, _card_table);
1348 _rem_set->initialize(max_reserved_regions());
1349
1350 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1351 guarantee(G1HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1352 guarantee(G1HeapRegion::CardsPerRegion < max_cards_per_region,
1353 "too many cards per region");
1354
1355 HeapRegionRemSet::initialize(_reserved);
1356
1357 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1358
1359 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1360
1361 {
1362 size_t granularity = G1HeapRegion::GrainBytes;
1363
1364 _region_attr.initialize(reserved(), granularity);
1365 }
1366
1367 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1368 if (_workers == nullptr) {
1369 return JNI_ENOMEM;
1370 }
1371 _workers->initialize_workers();
1372
1373 _numa->set_region_info(G1HeapRegion::GrainBytes, page_size);
1374
1375 // Create the G1ConcurrentMark data structure and thread.
1376 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1377 _cm = new G1ConcurrentMark(this, bitmap_storage);
1378 _cm_thread = _cm->cm_thread();
1379
1380 // Now expand into the initial heap size.
1381 if (!expand(init_byte_size, _workers)) {
1382 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1383 return JNI_ENOMEM;
1384 }
1385
1386 // Perform any initialization actions delegated to the policy.
1387 policy()->init(this, &_collection_set);
1388
1389 jint ecode = initialize_concurrent_refinement();
1390 if (ecode != JNI_OK) {
1391 return ecode;
1392 }
1393
1394 ecode = initialize_service_thread();
1395 if (ecode != JNI_OK) {
1396 return ecode;
1397 }
1398
1399 // Create and schedule the periodic gc task on the service thread.
1400 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1401 _service_thread->register_task(_periodic_gc_task);
1402
1403 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1404 _service_thread->register_task(_free_arena_memory_task);
1405
1406 // Here we allocate the dummy G1HeapRegion that is required by the
1407 // G1AllocRegion class.
1408 G1HeapRegion* dummy_region = _hrm.get_dummy_region();
1409
1410 // We'll re-use the same region whether the alloc region will
1411 // require BOT updates or not and, if it doesn't, then a non-young
1412 // region will complain that it cannot support allocations without
1413 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1414 dummy_region->set_eden();
1415 // Make sure it's full.
1416 dummy_region->set_top(dummy_region->end());
1417 G1AllocRegion::setup(this, dummy_region);
1418
1419 _allocator->init_mutator_alloc_regions();
1420
1421 // Do create of the monitoring and management support so that
1422 // values in the heap have been properly initialized.
1423 _monitoring_support = new G1MonitoringSupport(this);
1424
1425 _collection_set.initialize(max_reserved_regions());
1426
1427 allocation_failure_injector()->reset();
1428
1429 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_parallel_workers);
1430 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_conc_mark);
1431 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_conc_refine);
1432 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_service);
1433
1434 G1InitLogger::print();
1435
1436 SlidingForwarding::initialize(heap_rs.region(), G1HeapRegion::GrainWords);
1437
1438 return JNI_OK;
1439 }
1440
1441 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1442 return _cm_thread->should_terminate();
1443 }
1444
1445 void G1CollectedHeap::stop() {
1446 // Stop all concurrent threads. We do this to make sure these threads
1447 // do not continue to execute and access resources (e.g. logging)
1448 // that are destroyed during shutdown.
1449 _cr->stop();
1450 _service_thread->stop();
1451 _cm_thread->stop();
1452 }
1453
1454 void G1CollectedHeap::safepoint_synchronize_begin() {
1455 SuspendibleThreadSet::synchronize();
1456 }
1457
1458 void G1CollectedHeap::safepoint_synchronize_end() {
1459 SuspendibleThreadSet::desynchronize();
1460 }
1461
1462 void G1CollectedHeap::post_initialize() {
1463 CollectedHeap::post_initialize();
1464 ref_processing_init();
1465 }
1466
1467 void G1CollectedHeap::ref_processing_init() {
1468 // Reference processing in G1 currently works as follows:
1469 //
1470 // * There are two reference processor instances. One is
1471 // used to record and process discovered references
1472 // during concurrent marking; the other is used to
1473 // record and process references during STW pauses
1474 // (both full and incremental).
1475 // * Both ref processors need to 'span' the entire heap as
1476 // the regions in the collection set may be dotted around.
1477 //
1478 // * For the concurrent marking ref processor:
1479 // * Reference discovery is enabled at concurrent start.
1480 // * Reference discovery is disabled and the discovered
1481 // references processed etc during remarking.
1482 // * Reference discovery is MT (see below).
1483 // * Reference discovery requires a barrier (see below).
1484 // * Reference processing may or may not be MT
1485 // (depending on the value of ParallelRefProcEnabled
1486 // and ParallelGCThreads).
1487 // * A full GC disables reference discovery by the CM
1488 // ref processor and abandons any entries on it's
1489 // discovered lists.
1490 //
1491 // * For the STW processor:
1492 // * Non MT discovery is enabled at the start of a full GC.
1493 // * Processing and enqueueing during a full GC is non-MT.
1494 // * During a full GC, references are processed after marking.
1495 //
1496 // * Discovery (may or may not be MT) is enabled at the start
1497 // of an incremental evacuation pause.
1498 // * References are processed near the end of a STW evacuation pause.
1499 // * For both types of GC:
1500 // * Discovery is atomic - i.e. not concurrent.
1501 // * Reference discovery will not need a barrier.
1502
1503 _is_alive_closure_cm.initialize(concurrent_mark());
1504 // Concurrent Mark ref processor
1505 _ref_processor_cm =
1506 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1507 ParallelGCThreads, // degree of mt processing
1508 // We discover with the gc worker threads during Remark, so both
1509 // thread counts must be considered for discovery.
1510 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1511 true, // Reference discovery is concurrent
1512 &_is_alive_closure_cm); // is alive closure
1513
1514 // STW ref processor
1515 _ref_processor_stw =
1516 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1517 ParallelGCThreads, // degree of mt processing
1518 ParallelGCThreads, // degree of mt discovery
1519 false, // Reference discovery is not concurrent
1520 &_is_alive_closure_stw); // is alive closure
1521 }
1522
1523 size_t G1CollectedHeap::capacity() const {
1524 return _hrm.length() * G1HeapRegion::GrainBytes;
1525 }
1526
1527 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1528 return _hrm.total_free_bytes();
1529 }
1530
1531 // Computes the sum of the storage used by the various regions.
1532 size_t G1CollectedHeap::used() const {
1533 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1534 return result;
1535 }
1536
1537 size_t G1CollectedHeap::used_unlocked() const {
1538 return _summary_bytes_used;
1539 }
1540
1541 class SumUsedClosure: public HeapRegionClosure {
1542 size_t _used;
1543 public:
1544 SumUsedClosure() : _used(0) {}
1545 bool do_heap_region(G1HeapRegion* r) {
1546 _used += r->used();
1547 return false;
1548 }
1549 size_t result() { return _used; }
1550 };
1551
1552 size_t G1CollectedHeap::recalculate_used() const {
1553 SumUsedClosure blk;
1554 heap_region_iterate(&blk);
1555 return blk.result();
1556 }
1557
1558 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1559 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1560 }
1561
1562 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1563 switch (cause) {
1564 case GCCause::_g1_humongous_allocation: return true;
1565 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1566 case GCCause::_wb_breakpoint: return true;
1567 case GCCause::_codecache_GC_aggressive: return true;
1568 case GCCause::_codecache_GC_threshold: return true;
1569 default: return is_user_requested_concurrent_full_gc(cause);
1570 }
1571 }
1572
1573 void G1CollectedHeap::increment_old_marking_cycles_started() {
1574 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1575 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1576 "Wrong marking cycle count (started: %d, completed: %d)",
1577 _old_marking_cycles_started, _old_marking_cycles_completed);
1578
1579 _old_marking_cycles_started++;
1580 }
1581
1582 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1583 bool whole_heap_examined) {
1584 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1585
1586 // We assume that if concurrent == true, then the caller is a
1587 // concurrent thread that was joined the Suspendible Thread
1588 // Set. If there's ever a cheap way to check this, we should add an
1589 // assert here.
1590
1591 // Given that this method is called at the end of a Full GC or of a
1592 // concurrent cycle, and those can be nested (i.e., a Full GC can
1593 // interrupt a concurrent cycle), the number of full collections
1594 // completed should be either one (in the case where there was no
1595 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1596 // behind the number of full collections started.
1597
1598 // This is the case for the inner caller, i.e. a Full GC.
1599 assert(concurrent ||
1600 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1601 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1602 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1603 "is inconsistent with _old_marking_cycles_completed = %u",
1604 _old_marking_cycles_started, _old_marking_cycles_completed);
1605
1606 // This is the case for the outer caller, i.e. the concurrent cycle.
1607 assert(!concurrent ||
1608 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1609 "for outer caller (concurrent cycle): "
1610 "_old_marking_cycles_started = %u "
1611 "is inconsistent with _old_marking_cycles_completed = %u",
1612 _old_marking_cycles_started, _old_marking_cycles_completed);
1613
1614 _old_marking_cycles_completed += 1;
1615 if (whole_heap_examined) {
1616 // Signal that we have completed a visit to all live objects.
1617 record_whole_heap_examined_timestamp();
1618 }
1619
1620 // We need to clear the "in_progress" flag in the CM thread before
1621 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1622 // is set) so that if a waiter requests another System.gc() it doesn't
1623 // incorrectly see that a marking cycle is still in progress.
1624 if (concurrent) {
1625 _cm_thread->set_idle();
1626 }
1627
1628 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1629 // for a full GC to finish that their wait is over.
1630 ml.notify_all();
1631 }
1632
1633 // Helper for collect().
1634 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1635 MutexLocker ml(Heap_lock);
1636 return G1GCCounters(g1h);
1637 }
1638
1639 void G1CollectedHeap::collect(GCCause::Cause cause) {
1640 try_collect(cause, collection_counters(this));
1641 }
1642
1643 // Return true if (x < y) with allowance for wraparound.
1644 static bool gc_counter_less_than(uint x, uint y) {
1645 return (x - y) > (UINT_MAX/2);
1646 }
1647
1648 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1649 // Macro so msg printing is format-checked.
1650 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1651 do { \
1652 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1653 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1654 ResourceMark rm; /* For thread name. */ \
1655 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1656 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1657 Thread::current()->name(), \
1658 GCCause::to_string(cause)); \
1659 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1660 } \
1661 } while (0)
1662
1663 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1664 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1665
1666 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1667 uint gc_counter,
1668 uint old_marking_started_before) {
1669 assert_heap_not_locked();
1670 assert(should_do_concurrent_full_gc(cause),
1671 "Non-concurrent cause %s", GCCause::to_string(cause));
1672
1673 for (uint i = 1; true; ++i) {
1674 // Try to schedule concurrent start evacuation pause that will
1675 // start a concurrent cycle.
1676 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1677 VM_G1TryInitiateConcMark op(gc_counter, cause);
1678 VMThread::execute(&op);
1679
1680 // Request is trivially finished.
1681 if (cause == GCCause::_g1_periodic_collection) {
1682 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1683 return op.gc_succeeded();
1684 }
1685
1686 // If VMOp skipped initiating concurrent marking cycle because
1687 // we're terminating, then we're done.
1688 if (op.terminating()) {
1689 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1690 return false;
1691 }
1692
1693 // Lock to get consistent set of values.
1694 uint old_marking_started_after;
1695 uint old_marking_completed_after;
1696 {
1697 MutexLocker ml(Heap_lock);
1698 // Update gc_counter for retrying VMOp if needed. Captured here to be
1699 // consistent with the values we use below for termination tests. If
1700 // a retry is needed after a possible wait, and another collection
1701 // occurs in the meantime, it will cause our retry to be skipped and
1702 // we'll recheck for termination with updated conditions from that
1703 // more recent collection. That's what we want, rather than having
1704 // our retry possibly perform an unnecessary collection.
1705 gc_counter = total_collections();
1706 old_marking_started_after = _old_marking_cycles_started;
1707 old_marking_completed_after = _old_marking_cycles_completed;
1708 }
1709
1710 if (cause == GCCause::_wb_breakpoint) {
1711 if (op.gc_succeeded()) {
1712 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1713 return true;
1714 }
1715 // When _wb_breakpoint there can't be another cycle or deferred.
1716 assert(!op.cycle_already_in_progress(), "invariant");
1717 assert(!op.whitebox_attached(), "invariant");
1718 // Concurrent cycle attempt might have been cancelled by some other
1719 // collection, so retry. Unlike other cases below, we want to retry
1720 // even if cancelled by a STW full collection, because we really want
1721 // to start a concurrent cycle.
1722 if (old_marking_started_before != old_marking_started_after) {
1723 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1724 old_marking_started_before = old_marking_started_after;
1725 }
1726 } else if (!GCCause::is_user_requested_gc(cause)) {
1727 // For an "automatic" (not user-requested) collection, we just need to
1728 // ensure that progress is made.
1729 //
1730 // Request is finished if any of
1731 // (1) the VMOp successfully performed a GC,
1732 // (2) a concurrent cycle was already in progress,
1733 // (3) whitebox is controlling concurrent cycles,
1734 // (4) a new cycle was started (by this thread or some other), or
1735 // (5) a Full GC was performed.
1736 // Cases (4) and (5) are detected together by a change to
1737 // _old_marking_cycles_started.
1738 //
1739 // Note that (1) does not imply (4). If we're still in the mixed
1740 // phase of an earlier concurrent collection, the request to make the
1741 // collection a concurrent start won't be honored. If we don't check for
1742 // both conditions we'll spin doing back-to-back collections.
1743 if (op.gc_succeeded() ||
1744 op.cycle_already_in_progress() ||
1745 op.whitebox_attached() ||
1746 (old_marking_started_before != old_marking_started_after)) {
1747 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1748 return true;
1749 }
1750 } else { // User-requested GC.
1751 // For a user-requested collection, we want to ensure that a complete
1752 // full collection has been performed before returning, but without
1753 // waiting for more than needed.
1754
1755 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1756 // new cycle was started. That's good, because it's not clear what we
1757 // should do otherwise. Trying again just does back to back GCs.
1758 // Can't wait for someone else to start a cycle. And returning fails
1759 // to meet the goal of ensuring a full collection was performed.
1760 assert(!op.gc_succeeded() ||
1761 (old_marking_started_before != old_marking_started_after),
1762 "invariant: succeeded %s, started before %u, started after %u",
1763 BOOL_TO_STR(op.gc_succeeded()),
1764 old_marking_started_before, old_marking_started_after);
1765
1766 // Request is finished if a full collection (concurrent or stw)
1767 // was started after this request and has completed, e.g.
1768 // started_before < completed_after.
1769 if (gc_counter_less_than(old_marking_started_before,
1770 old_marking_completed_after)) {
1771 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1772 return true;
1773 }
1774
1775 if (old_marking_started_after != old_marking_completed_after) {
1776 // If there is an in-progress cycle (possibly started by us), then
1777 // wait for that cycle to complete, e.g.
1778 // while completed_now < started_after.
1779 LOG_COLLECT_CONCURRENTLY(cause, "wait");
1780 MonitorLocker ml(G1OldGCCount_lock);
1781 while (gc_counter_less_than(_old_marking_cycles_completed,
1782 old_marking_started_after)) {
1783 ml.wait();
1784 }
1785 // Request is finished if the collection we just waited for was
1786 // started after this request.
1787 if (old_marking_started_before != old_marking_started_after) {
1788 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
1789 return true;
1790 }
1791 }
1792
1793 // If VMOp was successful then it started a new cycle that the above
1794 // wait &etc should have recognized as finishing this request. This
1795 // differs from a non-user-request, where gc_succeeded does not imply
1796 // a new cycle was started.
1797 assert(!op.gc_succeeded(), "invariant");
1798
1799 if (op.cycle_already_in_progress()) {
1800 // If VMOp failed because a cycle was already in progress, it
1801 // is now complete. But it didn't finish this user-requested
1802 // GC, so try again.
1803 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
1804 continue;
1805 } else if (op.whitebox_attached()) {
1806 // If WhiteBox wants control, wait for notification of a state
1807 // change in the controller, then try again. Don't wait for
1808 // release of control, since collections may complete while in
1809 // control. Note: This won't recognize a STW full collection
1810 // while waiting; we can't wait on multiple monitors.
1811 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
1812 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
1813 if (ConcurrentGCBreakpoints::is_controlled()) {
1814 ml.wait();
1815 }
1816 continue;
1817 }
1818 }
1819
1820 // Collection failed and should be retried.
1821 assert(op.transient_failure(), "invariant");
1822
1823 LOG_COLLECT_CONCURRENTLY(cause, "retry");
1824 }
1825 }
1826
1827 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause,
1828 const G1GCCounters& counters_before) {
1829 assert_heap_not_locked();
1830
1831 while(true) {
1832 VM_G1CollectFull op(counters_before.total_collections(),
1833 counters_before.total_full_collections(),
1834 cause);
1835 VMThread::execute(&op);
1836
1837 // Request is trivially finished.
1838 if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) {
1839 return op.gc_succeeded();
1840 }
1841
1842 {
1843 MutexLocker ml(Heap_lock);
1844 if (counters_before.total_full_collections() != total_full_collections()) {
1845 return true;
1846 }
1847 }
1848 }
1849 }
1850
1851 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
1852 const G1GCCounters& counters_before) {
1853 if (should_do_concurrent_full_gc(cause)) {
1854 return try_collect_concurrently(cause,
1855 counters_before.total_collections(),
1856 counters_before.old_marking_cycles_started());
1857 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
1858 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1859
1860 // Schedule a standard evacuation pause. We're setting word_size
1861 // to 0 which means that we are not requesting a post-GC allocation.
1862 VM_G1CollectForAllocation op(0, /* word_size */
1863 counters_before.total_collections(),
1864 cause);
1865 VMThread::execute(&op);
1866 return op.gc_succeeded();
1867 } else {
1868 // Schedule a Full GC.
1869 return try_collect_fullgc(cause, counters_before);
1870 }
1871 }
1872
1873 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
1874 GCCauseSetter x(this, gc_cause);
1875
1876 // At this point we are supposed to start a concurrent cycle. We
1877 // will do so if one is not already in progress.
1878 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
1879 if (should_start) {
1880 do_collection_pause_at_safepoint();
1881 }
1882 }
1883
1884 bool G1CollectedHeap::is_in(const void* p) const {
1885 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
1886 }
1887
1888 // Iteration functions.
1889
1890 // Iterates an ObjectClosure over all objects within a G1HeapRegion.
1891
1892 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1893 ObjectClosure* _cl;
1894 public:
1895 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1896 bool do_heap_region(G1HeapRegion* r) {
1897 if (!r->is_continues_humongous()) {
1898 r->object_iterate(_cl);
1899 }
1900 return false;
1901 }
1902 };
1903
1904 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
1905 IterateObjectClosureRegionClosure blk(cl);
1906 heap_region_iterate(&blk);
1907 }
1908
1909 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
1910 private:
1911 G1CollectedHeap* _heap;
1912 HeapRegionClaimer _claimer;
1913
1914 public:
1915 G1ParallelObjectIterator(uint thread_num) :
1916 _heap(G1CollectedHeap::heap()),
1917 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
1918
1919 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1920 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
1921 }
1922 };
1923
1924 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
1925 return new G1ParallelObjectIterator(thread_num);
1926 }
1927
1928 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
1929 IterateObjectClosureRegionClosure blk(cl);
1930 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
1931 }
1932
1933 void G1CollectedHeap::keep_alive(oop obj) {
1934 G1BarrierSet::enqueue_preloaded(obj);
1935 }
1936
1937 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
1938 _hrm.iterate(cl);
1939 }
1940
1941 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
1942 _hrm.iterate(cl);
1943 }
1944
1945 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1946 HeapRegionClaimer *hrclaimer,
1947 uint worker_id) const {
1948 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
1949 }
1950
1951 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1952 HeapRegionClaimer *hrclaimer) const {
1953 _hrm.par_iterate(cl, hrclaimer, 0);
1954 }
1955
1956 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
1957 _collection_set.iterate(cl);
1958 }
1959
1960 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
1961 HeapRegionClaimer* hr_claimer,
1962 uint worker_id) {
1963 _collection_set.par_iterate(cl, hr_claimer, worker_id);
1964 }
1965
1966 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
1967 HeapRegionClaimer* hr_claimer,
1968 uint worker_id) {
1969 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
1970 }
1971
1972 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
1973 HeapRegionClaimer* hr_claimer,
1974 const uint regions[],
1975 size_t length,
1976 uint worker_id) const {
1977 assert_at_safepoint();
1978 if (length == 0) {
1979 return;
1980 }
1981 uint total_workers = workers()->active_workers();
1982
1983 size_t start_pos = (worker_id * length) / total_workers;
1984 size_t cur_pos = start_pos;
1985
1986 do {
1987 uint region_idx = regions[cur_pos];
1988 if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) {
1989 G1HeapRegion* r = region_at(region_idx);
1990 bool result = cl->do_heap_region(r);
1991 guarantee(!result, "Must not cancel iteration");
1992 }
1993
1994 cur_pos++;
1995 if (cur_pos == length) {
1996 cur_pos = 0;
1997 }
1998 } while (cur_pos != start_pos);
1999 }
2000
2001 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2002 G1HeapRegion* hr = heap_region_containing(addr);
2003 // The CollectedHeap API requires us to not fail for any given address within
2004 // the heap. G1HeapRegion::block_start() has been optimized to not accept addresses
2005 // outside of the allocated area.
2006 if (addr >= hr->top()) {
2007 return nullptr;
2008 }
2009 return hr->block_start(addr);
2010 }
2011
2012 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2013 G1HeapRegion* hr = heap_region_containing(addr);
2014 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2015 }
2016
2017 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2018 return (_policy->young_list_target_length() - _survivor.length()) * G1HeapRegion::GrainBytes;
2019 }
2020
2021 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2022 return _eden.length() * G1HeapRegion::GrainBytes;
2023 }
2024
2025 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2026 // must be equal to the humongous object limit.
2027 size_t G1CollectedHeap::max_tlab_size() const {
2028 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2029 }
2030
2031 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2032 return _allocator->unsafe_max_tlab_alloc();
2033 }
2034
2035 size_t G1CollectedHeap::max_capacity() const {
2036 return max_regions() * G1HeapRegion::GrainBytes;
2037 }
2038
2039 void G1CollectedHeap::prepare_for_verify() {
2040 _verifier->prepare_for_verify();
2041 }
2042
2043 void G1CollectedHeap::verify(VerifyOption vo) {
2044 _verifier->verify(vo);
2045 }
2046
2047 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2048 return true;
2049 }
2050
2051 class PrintRegionClosure: public HeapRegionClosure {
2052 outputStream* _st;
2053 public:
2054 PrintRegionClosure(outputStream* st) : _st(st) {}
2055 bool do_heap_region(G1HeapRegion* r) {
2056 r->print_on(_st);
2057 return false;
2058 }
2059 };
2060
2061 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2062 const G1HeapRegion* hr,
2063 const VerifyOption vo) const {
2064 switch (vo) {
2065 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2066 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2067 default: ShouldNotReachHere();
2068 }
2069 return false; // keep some compilers happy
2070 }
2071
2072 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2073 const VerifyOption vo) const {
2074 switch (vo) {
2075 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2076 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2077 default: ShouldNotReachHere();
2078 }
2079 return false; // keep some compilers happy
2080 }
2081
2082 void G1CollectedHeap::print_heap_regions() const {
2083 LogTarget(Trace, gc, heap, region) lt;
2084 if (lt.is_enabled()) {
2085 LogStream ls(lt);
2086 print_regions_on(&ls);
2087 }
2088 }
2089
2090 void G1CollectedHeap::print_on(outputStream* st) const {
2091 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2092 st->print(" %-20s", "garbage-first heap");
2093 st->print(" total reserved %zuK, committed %zuK, used %zuK",
2094 _hrm.reserved().byte_size()/K, capacity()/K, heap_used/K);
2095 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2096 p2i(_hrm.reserved().start()),
2097 p2i(_hrm.reserved().end()));
2098 st->cr();
2099 st->print(" region size " SIZE_FORMAT "K, ", G1HeapRegion::GrainBytes / K);
2100 uint young_regions = young_regions_count();
2101 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2102 (size_t) young_regions * G1HeapRegion::GrainBytes / K);
2103 uint survivor_regions = survivor_regions_count();
2104 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2105 (size_t) survivor_regions * G1HeapRegion::GrainBytes / K);
2106 st->cr();
2107 if (_numa->is_enabled()) {
2108 uint num_nodes = _numa->num_active_nodes();
2109 st->print(" remaining free region(s) on each NUMA node: ");
2110 const uint* node_ids = _numa->node_ids();
2111 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2112 uint num_free_regions = _hrm.num_free_regions(node_index);
2113 st->print("%u=%u ", node_ids[node_index], num_free_regions);
2114 }
2115 st->cr();
2116 }
2117 MetaspaceUtils::print_on(st);
2118 }
2119
2120 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2121 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2122 "HS=humongous(starts), HC=humongous(continues), "
2123 "CS=collection set, F=free, "
2124 "TAMS=top-at-mark-start, "
2125 "PB=parsable bottom");
2126 PrintRegionClosure blk(st);
2127 heap_region_iterate(&blk);
2128 }
2129
2130 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2131 print_on(st);
2132
2133 // Print the per-region information.
2134 st->cr();
2135 print_regions_on(st);
2136 }
2137
2138 void G1CollectedHeap::print_on_error(outputStream* st) const {
2139 this->CollectedHeap::print_on_error(st);
2140
2141 if (_cm != nullptr) {
2142 st->cr();
2143 _cm->print_on_error(st);
2144 }
2145 }
2146
2147 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2148 workers()->threads_do(tc);
2149 tc->do_thread(_cm_thread);
2150 _cm->threads_do(tc);
2151 _cr->threads_do(tc);
2152 tc->do_thread(_service_thread);
2153 }
2154
2155 void G1CollectedHeap::print_tracing_info() const {
2156 rem_set()->print_summary_info();
2157 concurrent_mark()->print_summary_info();
2158 }
2159
2160 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2161 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2162 }
2163
2164 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2165
2166 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2167 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2168 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2169 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2170
2171 size_t eden_capacity_bytes =
2172 (policy()->young_list_target_length() * G1HeapRegion::GrainBytes) - survivor_used_bytes;
2173
2174 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2175 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2176 survivor_used_bytes, old_gen_used_bytes, num_regions());
2177 }
2178
2179 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2180 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2181 stats->unused(), stats->used(), stats->region_end_waste(),
2182 stats->regions_filled(), stats->num_plab_filled(),
2183 stats->direct_allocated(), stats->num_direct_allocated(),
2184 stats->failure_used(), stats->failure_waste());
2185 }
2186
2187 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2188 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2189 gc_tracer->report_gc_heap_summary(when, heap_summary);
2190
2191 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2192 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2193 }
2194
2195 void G1CollectedHeap::gc_prologue(bool full) {
2196 // Update common counters.
2197 increment_total_collections(full /* full gc */);
2198 if (full || collector_state()->in_concurrent_start_gc()) {
2199 increment_old_marking_cycles_started();
2200 }
2201 }
2202
2203 void G1CollectedHeap::gc_epilogue(bool full) {
2204 // Update common counters.
2205 if (full) {
2206 // Update the number of full collections that have been completed.
2207 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2208 }
2209
2210 #if COMPILER2_OR_JVMCI
2211 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2212 #endif
2213
2214 // We have just completed a GC. Update the soft reference
2215 // policy with the new heap occupancy
2216 Universe::heap()->update_capacity_and_used_at_gc();
2217
2218 _collection_pause_end = Ticks::now();
2219
2220 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2221 &_collection_set_candidates_card_set_stats);
2222
2223 update_parallel_gc_threads_cpu_time();
2224 }
2225
2226 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2227 return _hrm.uncommit_inactive_regions(region_limit);
2228 }
2229
2230 bool G1CollectedHeap::has_uncommittable_regions() {
2231 return _hrm.has_inactive_regions();
2232 }
2233
2234 void G1CollectedHeap::uncommit_regions_if_necessary() {
2235 if (has_uncommittable_regions()) {
2236 G1UncommitRegionTask::enqueue();
2237 }
2238 }
2239
2240 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2241 LogTarget(Trace, gc, heap, verify) lt;
2242
2243 if (lt.is_enabled()) {
2244 LogStream ls(lt);
2245 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2246 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2247 heap_region_iterate(&cl);
2248 }
2249 }
2250
2251 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2252 uint gc_count_before,
2253 bool* succeeded,
2254 GCCause::Cause gc_cause) {
2255 assert_heap_not_locked_and_not_at_safepoint();
2256 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2257 VMThread::execute(&op);
2258
2259 HeapWord* result = op.result();
2260 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2261 assert(result == nullptr || ret_succeeded,
2262 "the result should be null if the VM did not succeed");
2263 *succeeded = ret_succeeded;
2264
2265 assert_heap_not_locked();
2266 return result;
2267 }
2268
2269 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2270 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2271
2272 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2273 if (concurrent_operation_is_full_mark) {
2274 _cm->post_concurrent_mark_start();
2275 _cm_thread->start_full_mark();
2276 } else {
2277 _cm->post_concurrent_undo_start();
2278 _cm_thread->start_undo_mark();
2279 }
2280 CGC_lock->notify();
2281 }
2282
2283 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(G1HeapRegion* r) const {
2284 // We don't nominate objects with many remembered set entries, on
2285 // the assumption that such objects are likely still live.
2286 HeapRegionRemSet* rem_set = r->rem_set();
2287
2288 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2289 }
2290
2291 #ifndef PRODUCT
2292 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2293 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2294 public:
2295 virtual bool do_heap_region(G1HeapRegion* r) {
2296 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2297 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2298 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2299 "Region %u remset tracking status (%s) different to region attribute (%s)",
2300 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2301 return false;
2302 }
2303 } cl;
2304 heap_region_iterate(&cl);
2305 }
2306 #endif
2307
2308 void G1CollectedHeap::update_parallel_gc_threads_cpu_time() {
2309 assert(Thread::current()->is_VM_thread(),
2310 "Must be called from VM thread to avoid races");
2311 if (!UsePerfData || !os::is_thread_cpu_time_supported()) {
2312 return;
2313 }
2314
2315 // Ensure ThreadTotalCPUTimeClosure destructor is called before publishing gc
2316 // time.
2317 {
2318 ThreadTotalCPUTimeClosure tttc(CPUTimeGroups::CPUTimeType::gc_parallel_workers);
2319 // Currently parallel worker threads never terminate (JDK-8081682), so it is
2320 // safe for VMThread to read their CPU times. However, if JDK-8087340 is
2321 // resolved so they terminate, we should rethink if it is still safe.
2322 workers()->threads_do(&tttc);
2323 }
2324
2325 CPUTimeCounters::publish_gc_total_cpu_time();
2326 }
2327
2328 void G1CollectedHeap::start_new_collection_set() {
2329 collection_set()->start_incremental_building();
2330
2331 clear_region_attr();
2332
2333 guarantee(_eden.length() == 0, "eden should have been cleared");
2334 policy()->transfer_survivors_to_cset(survivor());
2335
2336 // We redo the verification but now wrt to the new CSet which
2337 // has just got initialized after the previous CSet was freed.
2338 _cm->verify_no_collection_set_oops();
2339 }
2340
2341 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2342 if (collector_state()->in_concurrent_start_gc()) {
2343 return G1HeapVerifier::G1VerifyConcurrentStart;
2344 } else if (collector_state()->in_young_only_phase()) {
2345 return G1HeapVerifier::G1VerifyYoungNormal;
2346 } else {
2347 return G1HeapVerifier::G1VerifyMixed;
2348 }
2349 }
2350
2351 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2352 if (!VerifyBeforeGC) {
2353 return;
2354 }
2355 if (!G1HeapVerifier::should_verify(type)) {
2356 return;
2357 }
2358 Ticks start = Ticks::now();
2359 _verifier->prepare_for_verify();
2360 _verifier->verify_region_sets_optional();
2361 _verifier->verify_dirty_young_regions();
2362 _verifier->verify_before_gc();
2363 verify_numa_regions("GC Start");
2364 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2365 }
2366
2367 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2368 if (!VerifyAfterGC) {
2369 return;
2370 }
2371 if (!G1HeapVerifier::should_verify(type)) {
2372 return;
2373 }
2374 Ticks start = Ticks::now();
2375 _verifier->verify_after_gc();
2376 verify_numa_regions("GC End");
2377 _verifier->verify_region_sets_optional();
2378
2379 if (collector_state()->in_concurrent_start_gc()) {
2380 log_debug(gc, verify)("Marking state");
2381 _verifier->verify_marking_state();
2382 }
2383
2384 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2385 }
2386
2387 void G1CollectedHeap::expand_heap_after_young_collection(){
2388 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2389 if (expand_bytes > 0) {
2390 // No need for an ergo logging here,
2391 // expansion_amount() does this when it returns a value > 0.
2392 double expand_ms = 0.0;
2393 if (!expand(expand_bytes, _workers, &expand_ms)) {
2394 // We failed to expand the heap. Cannot do anything about it.
2395 }
2396 phase_times()->record_expand_heap_time(expand_ms);
2397 }
2398 }
2399
2400 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2401 assert_at_safepoint_on_vm_thread();
2402 guarantee(!is_stw_gc_active(), "collection is not reentrant");
2403
2404 do_collection_pause_at_safepoint_helper();
2405 return true;
2406 }
2407
2408 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2409 // This summary needs to be printed before incrementing total collections.
2410 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2411 _g1h->total_collections(),
2412 true /* show_thread_times */);
2413 _g1h->print_heap_before_gc();
2414 _g1h->print_heap_regions();
2415 }
2416
2417 G1HeapPrinterMark::~G1HeapPrinterMark() {
2418 _g1h->policy()->print_age_table();
2419 _g1h->rem_set()->print_coarsen_stats();
2420 // We are at the end of the GC. Total collections has already been increased.
2421 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2422 _g1h->total_collections() - 1,
2423 false /* show_thread_times */);
2424
2425 _heap_transition.print();
2426 _g1h->print_heap_regions();
2427 _g1h->print_heap_after_gc();
2428 // Print NUMA statistics.
2429 _g1h->numa()->print_statistics();
2430 }
2431
2432 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2433 _timer(timer), _tracer(tracer) {
2434
2435 _timer->register_gc_start();
2436 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2437 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2438 }
2439
2440 G1JFRTracerMark::~G1JFRTracerMark() {
2441 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2442 _timer->register_gc_end();
2443 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2444 }
2445
2446 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2447 Ticks start = Ticks::now();
2448
2449 _survivor_evac_stats.adjust_desired_plab_size();
2450 _old_evac_stats.adjust_desired_plab_size();
2451
2452 // Start a new incremental collection set for the mutator phase.
2453 start_new_collection_set();
2454 _allocator->init_mutator_alloc_regions();
2455
2456 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2457 }
2458
2459 void G1CollectedHeap::retire_tlabs() {
2460 ensure_parsability(true);
2461 }
2462
2463 void G1CollectedHeap::flush_region_pin_cache() {
2464 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
2465 G1ThreadLocalData::pin_count_cache(thread).flush();
2466 }
2467 }
2468
2469 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2470 ResourceMark rm;
2471
2472 IsSTWGCActiveMark active_gc_mark;
2473 GCIdMark gc_id_mark;
2474 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2475
2476 GCTraceCPUTime tcpu(_gc_tracer_stw);
2477
2478 _bytes_used_during_gc = 0;
2479
2480 policy()->decide_on_concurrent_start_pause();
2481 // Record whether this pause may need to trigger a concurrent operation. Later,
2482 // when we signal the G1ConcurrentMarkThread, the collector state has already
2483 // been reset for the next pause.
2484 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2485
2486 // Perform the collection.
2487 G1YoungCollector collector(gc_cause());
2488 collector.collect();
2489
2490 // It should now be safe to tell the concurrent mark thread to start
2491 // without its logging output interfering with the logging output
2492 // that came from the pause.
2493 if (should_start_concurrent_mark_operation) {
2494 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2495 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2496 // thread(s) could be running concurrently with us. Make sure that anything
2497 // after this point does not assume that we are the only GC thread running.
2498 // Note: of course, the actual marking work will not start until the safepoint
2499 // itself is released in SuspendibleThreadSet::desynchronize().
2500 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2501 ConcurrentGCBreakpoints::notify_idle_to_active();
2502 }
2503 }
2504
2505 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2506 uint num_workers = workers()->active_workers();
2507 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2508 workers()->run_task(&unlink_task);
2509 }
2510
2511 void G1CollectedHeap::unload_classes_and_code(const char* description, BoolObjectClosure* is_alive, GCTimer* timer) {
2512 GCTraceTime(Debug, gc, phases) debug(description, timer);
2513
2514 ClassUnloadingContext ctx(workers()->active_workers(),
2515 false /* unregister_nmethods_during_purge */,
2516 false /* lock_nmethod_free_separately */);
2517 {
2518 CodeCache::UnlinkingScope scope(is_alive);
2519 bool unloading_occurred = SystemDictionary::do_unloading(timer);
2520 GCTraceTime(Debug, gc, phases) t("G1 Complete Cleaning", timer);
2521 complete_cleaning(unloading_occurred);
2522 }
2523 {
2524 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", timer);
2525 ctx.purge_nmethods();
2526 }
2527 {
2528 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", timer);
2529 G1CollectedHeap::heap()->bulk_unregister_nmethods();
2530 }
2531 {
2532 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", timer);
2533 ctx.free_nmethods();
2534 }
2535 {
2536 GCTraceTime(Debug, gc, phases) t("Purge Class Loader Data", timer);
2537 ClassLoaderDataGraph::purge(true /* at_safepoint */);
2538 DEBUG_ONLY(MetaspaceUtils::verify();)
2539 }
2540 }
2541
2542 class G1BulkUnregisterNMethodTask : public WorkerTask {
2543 HeapRegionClaimer _hrclaimer;
2544
2545 class UnregisterNMethodsHeapRegionClosure : public HeapRegionClosure {
2546 public:
2547
2548 bool do_heap_region(G1HeapRegion* hr) {
2549 hr->rem_set()->bulk_remove_code_roots();
2550 return false;
2551 }
2552 } _cl;
2553
2554 public:
2555 G1BulkUnregisterNMethodTask(uint num_workers)
2556 : WorkerTask("G1 Remove Unlinked NMethods From Code Root Set Task"),
2557 _hrclaimer(num_workers) { }
2558
2559 void work(uint worker_id) {
2560 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&_cl, &_hrclaimer, worker_id);
2561 }
2562 };
2563
2564 void G1CollectedHeap::bulk_unregister_nmethods() {
2565 uint num_workers = workers()->active_workers();
2566 G1BulkUnregisterNMethodTask t(num_workers);
2567 workers()->run_task(&t);
2568 }
2569
2570 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2571 assert(obj != nullptr, "must not be null");
2572 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2573 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2574 // may falsely indicate that this is not the case here: however the collection set only
2575 // contains old regions when concurrent mark is not running.
2576 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2577 }
2578
2579 void G1CollectedHeap::make_pending_list_reachable() {
2580 if (collector_state()->in_concurrent_start_gc()) {
2581 oop pll_head = Universe::reference_pending_list();
2582 if (pll_head != nullptr) {
2583 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2584 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2585 }
2586 }
2587 }
2588
2589 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2590 _num_humongous_objects = num_humongous_total;
2591 _num_humongous_reclaim_candidates = num_humongous_candidates;
2592 }
2593
2594 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2595 const G1CollectionSetCandidates* candidates = collection_set()->candidates();
2596 return !candidates->is_empty();
2597 }
2598
2599 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2600 _collection_set_candidates_card_set_stats = stats;
2601 }
2602
2603 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2604 _young_gen_card_set_stats = stats;
2605 }
2606
2607 void G1CollectedHeap::record_obj_copy_mem_stats() {
2608 policy()->old_gen_alloc_tracker()->
2609 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2610
2611 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2612 create_g1_evac_summary(&_old_evac_stats));
2613 }
2614
2615 void G1CollectedHeap::clear_bitmap_for_region(G1HeapRegion* hr) {
2616 concurrent_mark()->clear_bitmap_for_region(hr);
2617 }
2618
2619 void G1CollectedHeap::free_region(G1HeapRegion* hr, FreeRegionList* free_list) {
2620 assert(!hr->is_free(), "the region should not be free");
2621 assert(!hr->is_empty(), "the region should not be empty");
2622 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2623 assert(!hr->has_pinned_objects(),
2624 "must not free a region which contains pinned objects");
2625
2626 // Reset region metadata to allow reuse.
2627 hr->hr_clear(true /* clear_space */);
2628 _policy->remset_tracker()->update_at_free(hr);
2629
2630 if (free_list != nullptr) {
2631 free_list->add_ordered(hr);
2632 }
2633 }
2634
2635 void G1CollectedHeap::retain_region(G1HeapRegion* hr) {
2636 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
2637 collection_set()->candidates()->add_retained_region_unsorted(hr);
2638 }
2639
2640 void G1CollectedHeap::free_humongous_region(G1HeapRegion* hr,
2641 FreeRegionList* free_list) {
2642 assert(hr->is_humongous(), "this is only for humongous regions");
2643 hr->clear_humongous();
2644 free_region(hr, free_list);
2645 }
2646
2647 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2648 const uint humongous_regions_removed) {
2649 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
2650 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2651 _old_set.bulk_remove(old_regions_removed);
2652 _humongous_set.bulk_remove(humongous_regions_removed);
2653 }
2654
2655 }
2656
2657 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2658 assert(list != nullptr, "list can't be null");
2659 if (!list->is_empty()) {
2660 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2661 _hrm.insert_list_into_free_list(list);
2662 }
2663 }
2664
2665 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2666 decrease_used(bytes);
2667 }
2668
2669 void G1CollectedHeap::clear_eden() {
2670 _eden.clear();
2671 }
2672
2673 void G1CollectedHeap::clear_collection_set() {
2674 collection_set()->clear();
2675 }
2676
2677 void G1CollectedHeap::rebuild_free_region_list() {
2678 Ticks start = Ticks::now();
2679 _hrm.rebuild_free_list(workers());
2680 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2681 }
2682
2683 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2684 public:
2685 virtual bool do_heap_region(G1HeapRegion* r) {
2686 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2687 G1CollectedHeap::heap()->clear_region_attr(r);
2688 r->clear_young_index_in_cset();
2689 return false;
2690 }
2691 };
2692
2693 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2694 G1AbandonCollectionSetClosure cl;
2695 collection_set_iterate_all(&cl);
2696
2697 collection_set->clear();
2698 collection_set->stop_incremental_building();
2699 }
2700
2701 bool G1CollectedHeap::is_old_gc_alloc_region(G1HeapRegion* hr) {
2702 return _allocator->is_retained_old_region(hr);
2703 }
2704
2705 void G1CollectedHeap::set_region_short_lived_locked(G1HeapRegion* hr) {
2706 _eden.add(hr);
2707 _policy->set_region_eden(hr);
2708 }
2709
2710 #ifdef ASSERT
2711
2712 class NoYoungRegionsClosure: public HeapRegionClosure {
2713 private:
2714 bool _success;
2715 public:
2716 NoYoungRegionsClosure() : _success(true) { }
2717 bool do_heap_region(G1HeapRegion* r) {
2718 if (r->is_young()) {
2719 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2720 p2i(r->bottom()), p2i(r->end()));
2721 _success = false;
2722 }
2723 return false;
2724 }
2725 bool success() { return _success; }
2726 };
2727
2728 bool G1CollectedHeap::check_young_list_empty() {
2729 bool ret = (young_regions_count() == 0);
2730
2731 NoYoungRegionsClosure closure;
2732 heap_region_iterate(&closure);
2733 ret = ret && closure.success();
2734
2735 return ret;
2736 }
2737
2738 #endif // ASSERT
2739
2740 // Remove the given G1HeapRegion from the appropriate region set.
2741 void G1CollectedHeap::prepare_region_for_full_compaction(G1HeapRegion* hr) {
2742 if (hr->is_humongous()) {
2743 _humongous_set.remove(hr);
2744 } else if (hr->is_old()) {
2745 _old_set.remove(hr);
2746 } else if (hr->is_young()) {
2747 // Note that emptying the eden and survivor lists is postponed and instead
2748 // done as the first step when rebuilding the regions sets again. The reason
2749 // for this is that during a full GC string deduplication needs to know if
2750 // a collected region was young or old when the full GC was initiated.
2751 hr->uninstall_surv_rate_group();
2752 } else {
2753 // We ignore free regions, we'll empty the free list afterwards.
2754 assert(hr->is_free(), "it cannot be another type");
2755 }
2756 }
2757
2758 void G1CollectedHeap::increase_used(size_t bytes) {
2759 _summary_bytes_used += bytes;
2760 }
2761
2762 void G1CollectedHeap::decrease_used(size_t bytes) {
2763 assert(_summary_bytes_used >= bytes,
2764 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2765 _summary_bytes_used, bytes);
2766 _summary_bytes_used -= bytes;
2767 }
2768
2769 void G1CollectedHeap::set_used(size_t bytes) {
2770 _summary_bytes_used = bytes;
2771 }
2772
2773 class RebuildRegionSetsClosure : public HeapRegionClosure {
2774 private:
2775 bool _free_list_only;
2776
2777 HeapRegionSet* _old_set;
2778 HeapRegionSet* _humongous_set;
2779
2780 HeapRegionManager* _hrm;
2781
2782 size_t _total_used;
2783
2784 public:
2785 RebuildRegionSetsClosure(bool free_list_only,
2786 HeapRegionSet* old_set,
2787 HeapRegionSet* humongous_set,
2788 HeapRegionManager* hrm) :
2789 _free_list_only(free_list_only), _old_set(old_set),
2790 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2791 assert(_hrm->num_free_regions() == 0, "pre-condition");
2792 if (!free_list_only) {
2793 assert(_old_set->is_empty(), "pre-condition");
2794 assert(_humongous_set->is_empty(), "pre-condition");
2795 }
2796 }
2797
2798 bool do_heap_region(G1HeapRegion* r) {
2799 if (r->is_empty()) {
2800 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2801 // Add free regions to the free list
2802 r->set_free();
2803 _hrm->insert_into_free_list(r);
2804 } else if (!_free_list_only) {
2805 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2806
2807 if (r->is_humongous()) {
2808 _humongous_set->add(r);
2809 } else {
2810 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2811 // We now move all (non-humongous, non-old) regions to old gen,
2812 // and register them as such.
2813 r->move_to_old();
2814 _old_set->add(r);
2815 }
2816 _total_used += r->used();
2817 }
2818
2819 return false;
2820 }
2821
2822 size_t total_used() {
2823 return _total_used;
2824 }
2825 };
2826
2827 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2828 assert_at_safepoint_on_vm_thread();
2829
2830 if (!free_list_only) {
2831 _eden.clear();
2832 _survivor.clear();
2833 }
2834
2835 RebuildRegionSetsClosure cl(free_list_only,
2836 &_old_set, &_humongous_set,
2837 &_hrm);
2838 heap_region_iterate(&cl);
2839
2840 if (!free_list_only) {
2841 set_used(cl.total_used());
2842 }
2843 assert_used_and_recalculate_used_equal(this);
2844 }
2845
2846 // Methods for the mutator alloc region
2847
2848 G1HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2849 uint node_index) {
2850 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2851 bool should_allocate = policy()->should_allocate_mutator_region();
2852 if (should_allocate) {
2853 G1HeapRegion* new_alloc_region = new_region(word_size,
2854 HeapRegionType::Eden,
2855 false /* do_expand */,
2856 node_index);
2857 if (new_alloc_region != nullptr) {
2858 set_region_short_lived_locked(new_alloc_region);
2859 G1HeapRegionPrinter::alloc(new_alloc_region);
2860 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2861 return new_alloc_region;
2862 }
2863 }
2864 return nullptr;
2865 }
2866
2867 void G1CollectedHeap::retire_mutator_alloc_region(G1HeapRegion* alloc_region,
2868 size_t allocated_bytes) {
2869 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2870 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
2871
2872 collection_set()->add_eden_region(alloc_region);
2873 increase_used(allocated_bytes);
2874 _eden.add_used_bytes(allocated_bytes);
2875 G1HeapRegionPrinter::retire(alloc_region);
2876
2877 // We update the eden sizes here, when the region is retired,
2878 // instead of when it's allocated, since this is the point that its
2879 // used space has been recorded in _summary_bytes_used.
2880 monitoring_support()->update_eden_size();
2881 }
2882
2883 // Methods for the GC alloc regions
2884
2885 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
2886 if (dest.is_old()) {
2887 return true;
2888 } else {
2889 return survivor_regions_count() < policy()->max_survivor_regions();
2890 }
2891 }
2892
2893 G1HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
2894 assert(FreeList_lock->owned_by_self(), "pre-condition");
2895
2896 if (!has_more_regions(dest)) {
2897 return nullptr;
2898 }
2899
2900 HeapRegionType type;
2901 if (dest.is_young()) {
2902 type = HeapRegionType::Survivor;
2903 } else {
2904 type = HeapRegionType::Old;
2905 }
2906
2907 G1HeapRegion* new_alloc_region = new_region(word_size,
2908 type,
2909 true /* do_expand */,
2910 node_index);
2911
2912 if (new_alloc_region != nullptr) {
2913 if (type.is_survivor()) {
2914 new_alloc_region->set_survivor();
2915 _survivor.add(new_alloc_region);
2916 register_new_survivor_region_with_region_attr(new_alloc_region);
2917 } else {
2918 new_alloc_region->set_old();
2919 }
2920 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2921 register_region_with_region_attr(new_alloc_region);
2922 G1HeapRegionPrinter::alloc(new_alloc_region);
2923 return new_alloc_region;
2924 }
2925 return nullptr;
2926 }
2927
2928 void G1CollectedHeap::retire_gc_alloc_region(G1HeapRegion* alloc_region,
2929 size_t allocated_bytes,
2930 G1HeapRegionAttr dest) {
2931 _bytes_used_during_gc += allocated_bytes;
2932 if (dest.is_old()) {
2933 old_set_add(alloc_region);
2934 } else {
2935 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
2936 _survivor.add_used_bytes(allocated_bytes);
2937 }
2938
2939 bool const during_im = collector_state()->in_concurrent_start_gc();
2940 if (during_im && allocated_bytes > 0) {
2941 _cm->add_root_region(alloc_region);
2942 }
2943 G1HeapRegionPrinter::retire(alloc_region);
2944 }
2945
2946 G1HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
2947 bool expanded = false;
2948 uint index = _hrm.find_highest_free(&expanded);
2949
2950 if (index != G1_NO_HRM_INDEX) {
2951 if (expanded) {
2952 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
2953 G1HeapRegion::GrainWords * HeapWordSize);
2954 }
2955 return _hrm.allocate_free_regions_starting_at(index, 1);
2956 }
2957 return nullptr;
2958 }
2959
2960 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
2961 assert(!_cm->is_marked_in_bitmap(obj), "must be");
2962
2963 _cm->raw_mark_in_bitmap(obj);
2964 }
2965
2966 // Optimized nmethod scanning
2967 class RegisterNMethodOopClosure: public OopClosure {
2968 G1CollectedHeap* _g1h;
2969 nmethod* _nm;
2970
2971 public:
2972 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
2973 _g1h(g1h), _nm(nm) {}
2974
2975 void do_oop(oop* p) {
2976 oop heap_oop = RawAccess<>::oop_load(p);
2977 if (!CompressedOops::is_null(heap_oop)) {
2978 oop obj = CompressedOops::decode_not_null(heap_oop);
2979 G1HeapRegion* hr = _g1h->heap_region_containing(obj);
2980 assert(!hr->is_continues_humongous(),
2981 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
2982 " starting at " HR_FORMAT,
2983 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
2984
2985 hr->add_code_root(_nm);
2986 }
2987 }
2988
2989 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2990 };
2991
2992 void G1CollectedHeap::register_nmethod(nmethod* nm) {
2993 guarantee(nm != nullptr, "sanity");
2994 RegisterNMethodOopClosure reg_cl(this, nm);
2995 nm->oops_do(®_cl);
2996 }
2997
2998 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
2999 // We always unregister nmethods in bulk during code unloading only.
3000 ShouldNotReachHere();
3001 }
3002
3003 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3004 if (evacuation_failed) {
3005 set_used(recalculate_used());
3006 } else {
3007 // The "used" of the collection set have already been subtracted
3008 // when they were freed. Add in the bytes used.
3009 increase_used(_bytes_used_during_gc);
3010 }
3011 }
3012
3013 class RebuildCodeRootClosure: public NMethodClosure {
3014 G1CollectedHeap* _g1h;
3015
3016 public:
3017 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3018 _g1h(g1h) {}
3019
3020 void do_nmethod(nmethod* nm) {
3021 assert(nm != nullptr, "Sanity");
3022 _g1h->register_nmethod(nm);
3023 }
3024 };
3025
3026 void G1CollectedHeap::rebuild_code_roots() {
3027 RebuildCodeRootClosure nmethod_cl(this);
3028 CodeCache::nmethods_do(&nmethod_cl);
3029 }
3030
3031 void G1CollectedHeap::initialize_serviceability() {
3032 _monitoring_support->initialize_serviceability();
3033 }
3034
3035 MemoryUsage G1CollectedHeap::memory_usage() {
3036 return _monitoring_support->memory_usage();
3037 }
3038
3039 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3040 return _monitoring_support->memory_managers();
3041 }
3042
3043 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3044 return _monitoring_support->memory_pools();
3045 }
3046
3047 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3048 G1HeapRegion* region = heap_region_containing(start);
3049 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3050 }
3051
3052 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3053 // We can reach here with an active code cache marking cycle either because the
3054 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3055 // concurrent start young collection was below the threshold) or aborted. See
3056 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3057 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3058 // still have to arm all nmethod entry barriers. They are needed for adding oop
3059 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3060 if (!CodeCache::is_gc_marking_cycle_active()) {
3061 CodeCache::on_gc_marking_cycle_start();
3062 }
3063 if (concurrent_mark_start) {
3064 CodeCache::arm_all_nmethods();
3065 }
3066 }
3067
3068 void G1CollectedHeap::finish_codecache_marking_cycle() {
3069 CodeCache::on_gc_marking_cycle_finish();
3070 CodeCache::arm_all_nmethods();
3071 }