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.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "code/codeCache.hpp"
30 #include "compiler/oopMap.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1BatchedTask.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectionSetCandidates.hpp"
38 #include "gc/g1/g1CollectorState.hpp"
39 #include "gc/g1/g1ConcurrentRefine.hpp"
40 #include "gc/g1/g1ConcurrentRefineThread.hpp"
41 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
42 #include "gc/g1/g1DirtyCardQueue.hpp"
43 #include "gc/g1/g1EvacStats.inline.hpp"
44 #include "gc/g1/g1FullCollector.hpp"
45 #include "gc/g1/g1GCCounters.hpp"
46 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
47 #include "gc/g1/g1GCPhaseTimes.hpp"
48 #include "gc/g1/g1GCPauseType.hpp"
49 #include "gc/g1/g1HeapRegion.inline.hpp"
50 #include "gc/g1/g1HeapRegionRemSet.inline.hpp"
51 #include "gc/g1/g1HeapRegionSet.inline.hpp"
52 #include "gc/g1/g1HeapSizingPolicy.hpp"
53 #include "gc/g1/g1HeapTransition.hpp"
54 #include "gc/g1/g1HeapVerifier.hpp"
55 #include "gc/g1/g1InitLogger.hpp"
56 #include "gc/g1/g1MemoryPool.hpp"
57 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp"
58 #include "gc/g1/g1OopClosures.inline.hpp"
59 #include "gc/g1/g1ParallelCleaning.hpp"
60 #include "gc/g1/g1ParScanThreadState.inline.hpp"
61 #include "gc/g1/g1PeriodicGCTask.hpp"
62 #include "gc/g1/g1Policy.hpp"
63 #include "gc/g1/g1RedirtyCardsQueue.hpp"
64 #include "gc/g1/g1RegionPinCache.inline.hpp"
65 #include "gc/g1/g1RegionToSpaceMapper.hpp"
66 #include "gc/g1/g1RemSet.hpp"
67 #include "gc/g1/g1RootClosures.hpp"
68 #include "gc/g1/g1RootProcessor.hpp"
69 #include "gc/g1/g1SATBMarkQueueSet.hpp"
70 #include "gc/g1/g1ServiceThread.hpp"
71 #include "gc/g1/g1ThreadLocalData.hpp"
72 #include "gc/g1/g1Trace.hpp"
73 #include "gc/g1/g1UncommitRegionTask.hpp"
74 #include "gc/g1/g1VMOperations.hpp"
75 #include "gc/g1/g1YoungCollector.hpp"
76 #include "gc/g1/g1YoungGCAllocationFailureInjector.hpp"
77 #include "gc/shared/classUnloadingContext.hpp"
78 #include "gc/shared/concurrentGCBreakpoints.hpp"
79 #include "gc/shared/gcBehaviours.hpp"
80 #include "gc/shared/gcHeapSummary.hpp"
81 #include "gc/shared/gcId.hpp"
82 #include "gc/shared/gcTimer.hpp"
83 #include "gc/shared/gcTraceTime.inline.hpp"
84 #include "gc/shared/isGCActiveMark.hpp"
85 #include "gc/shared/locationPrinter.inline.hpp"
86 #include "gc/shared/oopStorageParState.hpp"
87 #include "gc/shared/preservedMarks.inline.hpp"
88 #include "gc/shared/referenceProcessor.inline.hpp"
89 #include "gc/shared/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 = HeapRegion::LogOfHRGrainBytes;
149 // Limit the expected input values to current known possible values of the
150 // (log) region size. Adjust as necessary after testing if changing the permissible
151 // values for region size.
152 assert(log_region_size >= 20 && log_region_size <= 29,
153 "expected value in [20,29], but got %u", log_region_size);
154 return 1u << (log_region_size / 2 - 4);
155 }
156
157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
158 MemRegion mr) {
159 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
160 }
161
162 // Private methods.
163
164 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
165 HeapRegionType type,
166 bool do_expand,
167 uint node_index) {
168 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
169 "the only time we use this to allocate a humongous region is "
170 "when we are allocating a single humongous region");
171
172 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
173
174 if (res == nullptr && do_expand) {
175 // Currently, only attempts to allocate GC alloc regions set
176 // do_expand to true. So, we should only reach here during a
177 // safepoint.
178 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
179
180 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
181 word_size * HeapWordSize);
182
183 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
184 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
185 word_size * HeapWordSize);
186 if (expand_single_region(node_index)) {
187 // Given that expand_single_region() succeeded in expanding the heap, and we
188 // always expand the heap by an amount aligned to the heap
189 // region size, the free list should in theory not be empty.
190 // In either case allocate_free_region() will check for null.
191 res = _hrm.allocate_free_region(type, node_index);
192 }
193 }
194 return res;
195 }
196
197 void G1CollectedHeap::set_humongous_metadata(HeapRegion* first_hr,
198 uint num_regions,
199 size_t word_size,
200 bool update_remsets) {
201 // Calculate the new top of the humongous object.
202 HeapWord* obj_top = first_hr->bottom() + word_size;
203 // The word size sum of all the regions used
204 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
205 assert(word_size <= word_size_sum, "sanity");
206
207 // How many words memory we "waste" which cannot hold a filler object.
208 size_t words_not_fillable = 0;
209
210 // Pad out the unused tail of the last region with filler
211 // objects, for improved usage accounting.
212
213 // How many words can we use for filler objects.
214 size_t words_fillable = word_size_sum - word_size;
215
216 if (words_fillable >= G1CollectedHeap::min_fill_size()) {
217 G1CollectedHeap::fill_with_objects(obj_top, words_fillable);
218 } else {
219 // We have space to fill, but we cannot fit an object there.
220 words_not_fillable = words_fillable;
221 words_fillable = 0;
222 }
223
224 // We will set up the first region as "starts humongous". This
225 // will also update the BOT covering all the regions to reflect
226 // that there is a single object that starts at the bottom of the
227 // first region.
228 first_hr->hr_clear(false /* clear_space */);
229 first_hr->set_starts_humongous(obj_top, words_fillable);
230
231 if (update_remsets) {
232 _policy->remset_tracker()->update_at_allocate(first_hr);
233 }
234
235 // Indices of first and last regions in the series.
236 uint first = first_hr->hrm_index();
237 uint last = first + num_regions - 1;
238
239 HeapRegion* hr = nullptr;
240 for (uint i = first + 1; i <= last; ++i) {
241 hr = region_at(i);
242 hr->hr_clear(false /* clear_space */);
243 hr->set_continues_humongous(first_hr);
244 if (update_remsets) {
245 _policy->remset_tracker()->update_at_allocate(hr);
246 }
247 }
248
249 // Up to this point no concurrent thread would have been able to
250 // do any scanning on any region in this series. All the top
251 // fields still point to bottom, so the intersection between
252 // [bottom,top] and [card_start,card_end] will be empty. Before we
253 // update the top fields, we'll do a storestore to make sure that
254 // no thread sees the update to top before the zeroing of the
255 // object header and the BOT initialization.
256 OrderAccess::storestore();
257
258 // Now, we will update the top fields of the "continues humongous"
259 // regions except the last one.
260 for (uint i = first; i < last; ++i) {
261 hr = region_at(i);
262 hr->set_top(hr->end());
263 }
264
265 hr = region_at(last);
266 // If we cannot fit a filler object, we must set top to the end
267 // of the humongous object, otherwise we cannot iterate the heap
268 // and the BOT will not be complete.
269 hr->set_top(hr->end() - words_not_fillable);
270
271 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
272 "obj_top should be in last region");
273
274 assert(words_not_fillable == 0 ||
275 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
276 "Miscalculation in humongous allocation");
277 }
278
279 HeapWord*
280 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
281 uint num_regions,
282 size_t word_size) {
283 assert(first_hr != nullptr, "pre-condition");
284 assert(is_humongous(word_size), "word_size should be humongous");
285 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
286
287 // Index of last region in the series.
288 uint first = first_hr->hrm_index();
289 uint last = first + num_regions - 1;
290
291 // We need to initialize the region(s) we just discovered. This is
292 // a bit tricky given that it can happen concurrently with
293 // refinement threads refining cards on these regions and
294 // potentially wanting to refine the BOT as they are scanning
295 // those cards (this can happen shortly after a cleanup; see CR
296 // 6991377). So we have to set up the region(s) carefully and in
297 // a specific order.
298
299 // The passed in hr will be the "starts humongous" region. The header
300 // of the new object will be placed at the bottom of this region.
301 HeapWord* new_obj = first_hr->bottom();
302
303 // First, we need to zero the header of the space that we will be
304 // allocating. When we update top further down, some refinement
305 // threads might try to scan the region. By zeroing the header we
306 // ensure that any thread that will try to scan the region will
307 // come across the zero klass word and bail out.
308 //
309 // NOTE: It would not have been correct to have used
310 // CollectedHeap::fill_with_object() and make the space look like
311 // an int array. The thread that is doing the allocation will
312 // later update the object header to a potentially different array
313 // type and, for a very short period of time, the klass and length
314 // fields will be inconsistent. This could cause a refinement
315 // thread to calculate the object size incorrectly.
316 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
317
318 // Next, update the metadata for the regions.
319 set_humongous_metadata(first_hr, num_regions, word_size, true);
320
321 HeapRegion* last_hr = region_at(last);
322 size_t used = byte_size(first_hr->bottom(), last_hr->top());
323
324 increase_used(used);
325
326 for (uint i = first; i <= last; ++i) {
327 HeapRegion *hr = region_at(i);
328 _humongous_set.add(hr);
329 _hr_printer.alloc(hr);
330 }
331
332 return new_obj;
333 }
334
335 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
336 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
337 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
338 }
339
340 // If could fit into free regions w/o expansion, try.
341 // Otherwise, if can expand, do so.
342 // Otherwise, if using ex regions might help, try with ex given back.
343 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
344 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
345
346 _verifier->verify_region_sets_optional();
347
348 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
349
350 // Policy: First try to allocate a humongous object in the free list.
351 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
352 if (humongous_start == nullptr) {
353 // Policy: We could not find enough regions for the humongous object in the
354 // free list. Look through the heap to find a mix of free and uncommitted regions.
355 // If so, expand the heap and allocate the humongous object.
356 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
357 if (humongous_start != nullptr) {
358 // We managed to find a region by expanding the heap.
359 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
360 word_size * HeapWordSize);
361 policy()->record_new_heap_size(num_regions());
362 } else {
363 // Policy: Potentially trigger a defragmentation GC.
364 }
365 }
366
367 HeapWord* result = nullptr;
368 if (humongous_start != nullptr) {
369 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
370 assert(result != nullptr, "it should always return a valid result");
371
372 // A successful humongous object allocation changes the used space
373 // information of the old generation so we need to recalculate the
374 // sizes and update the jstat counters here.
375 monitoring_support()->update_sizes();
376 }
377
378 _verifier->verify_region_sets_optional();
379
380 return result;
381 }
382
383 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
384 size_t requested_size,
385 size_t* actual_size) {
386 assert_heap_not_locked_and_not_at_safepoint();
387 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
388
389 return attempt_allocation(min_size, requested_size, actual_size);
390 }
391
392 HeapWord*
393 G1CollectedHeap::mem_allocate(size_t word_size,
394 bool* gc_overhead_limit_was_exceeded) {
395 assert_heap_not_locked_and_not_at_safepoint();
396
397 if (is_humongous(word_size)) {
398 return attempt_allocation_humongous(word_size);
399 }
400 size_t dummy = 0;
401 return attempt_allocation(word_size, word_size, &dummy);
402 }
403
404 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
405 ResourceMark rm; // For retrieving the thread names in log messages.
406
407 // Make sure you read the note in attempt_allocation_humongous().
408
409 assert_heap_not_locked_and_not_at_safepoint();
410 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
411 "be called for humongous allocation requests");
412
413 // We should only get here after the first-level allocation attempt
414 // (attempt_allocation()) failed to allocate.
415
416 // We will loop until a) we manage to successfully perform the 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 HeapRegion* curr_region = _hrm.addr_to_region(range.start());
477 HeapRegion* end_region = _hrm.addr_to_region(range.last());
478
479 while (curr_region != nullptr) {
480 bool is_last = curr_region == end_region;
481 HeapRegion* 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, HeapRegion::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 HeapRegion::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 = [&] (HeapRegion* 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 _hr_printer.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_part(MemRegion range) {
537 assert(!is_init_completed(), "Expect to be called at JVM init time");
538
539 iterate_regions_in_range(range,
540 [&] (HeapRegion* 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 = [&] (HeapRegion* 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 HeapRegion::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 * HeapRegion::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 * HeapRegion::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 private:
715 G1HRPrinter* _hr_printer;
716 public:
717 bool do_heap_region(HeapRegion* hr) {
718 assert(!hr->is_young(), "not expecting to find young regions");
719 _hr_printer->post_compaction(hr);
720 return false;
721 }
722
723 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
724 : _hr_printer(hr_printer) { }
725 };
726
727 void G1CollectedHeap::print_heap_after_full_collection() {
728 // Post collection region logging.
729 // We should do this after we potentially resize the heap so
730 // that all the COMMIT / UNCOMMIT events are generated before
731 // the compaction events.
732 if (_hr_printer.is_active()) {
733 PostCompactionPrinterClosure cl(hr_printer());
734 heap_region_iterate(&cl);
735 }
736 }
737
738 bool G1CollectedHeap::abort_concurrent_cycle() {
739 // Disable discovery and empty the discovered lists
740 // for the CM ref processor.
741 _ref_processor_cm->disable_discovery();
742 _ref_processor_cm->abandon_partial_discovery();
743 _ref_processor_cm->verify_no_references_recorded();
744
745 // Abandon current iterations of concurrent marking and concurrent
746 // refinement, if any are in progress.
747 return concurrent_mark()->concurrent_cycle_abort();
748 }
749
750 void G1CollectedHeap::prepare_heap_for_full_collection() {
751 // Make sure we'll choose a new allocation region afterwards.
752 _allocator->release_mutator_alloc_regions();
753 _allocator->abandon_gc_alloc_regions();
754
755 // We may have added regions to the current incremental collection
756 // set between the last GC or pause and now. We need to clear the
757 // incremental collection set and then start rebuilding it afresh
758 // after this full GC.
759 abandon_collection_set(collection_set());
760
761 _hrm.remove_all_free_regions();
762 }
763
764 void G1CollectedHeap::verify_before_full_collection() {
765 assert_used_and_recalculate_used_equal(this);
766 if (!VerifyBeforeGC) {
767 return;
768 }
769 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
770 return;
771 }
772 _verifier->verify_region_sets_optional();
773 _verifier->verify_before_gc();
774 _verifier->verify_bitmap_clear(true /* above_tams_only */);
775 }
776
777 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
778 // Prepare heap for normal collections.
779 assert(num_free_regions() == 0, "we should not have added any free regions");
780 rebuild_region_sets(false /* free_list_only */);
781 abort_refinement();
782 resize_heap_if_necessary();
783 uncommit_regions_if_necessary();
784
785 // Rebuild the code root lists for each region
786 rebuild_code_roots();
787
788 start_new_collection_set();
789 _allocator->init_mutator_alloc_regions();
790
791 // Post collection state updates.
792 MetaspaceGC::compute_new_size();
793 }
794
795 void G1CollectedHeap::abort_refinement() {
796 // Discard all remembered set updates and reset refinement statistics.
797 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
798 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
799 "DCQS should be empty");
800 concurrent_refine()->get_and_reset_refinement_stats();
801 }
802
803 void G1CollectedHeap::verify_after_full_collection() {
804 if (!VerifyAfterGC) {
805 return;
806 }
807 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
808 return;
809 }
810 _hrm.verify_optional();
811 _verifier->verify_region_sets_optional();
812 _verifier->verify_after_gc();
813 _verifier->verify_bitmap_clear(false /* above_tams_only */);
814
815 // At this point there should be no regions in the
816 // entire heap tagged as young.
817 assert(check_young_list_empty(), "young list should be empty at this point");
818
819 // Note: since we've just done a full GC, concurrent
820 // marking is no longer active. Therefore we need not
821 // re-enable reference discovery for the CM ref processor.
822 // That will be done at the start of the next marking cycle.
823 // We also know that the STW processor should no longer
824 // discover any new references.
825 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
826 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
827 _ref_processor_stw->verify_no_references_recorded();
828 _ref_processor_cm->verify_no_references_recorded();
829 }
830
831 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs,
832 bool do_maximal_compaction) {
833 assert_at_safepoint_on_vm_thread();
834
835 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
836 soft_ref_policy()->should_clear_all_soft_refs();
837
838 G1FullGCMark gc_mark;
839 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true);
840 G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
841
842 collector.prepare_collection();
843 collector.collect();
844 collector.complete_collection();
845
846 // Full collection was successfully completed.
847 return true;
848 }
849
850 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
851 // Currently, there is no facility in the do_full_collection(bool) API to notify
852 // the caller that the collection did not succeed (e.g., because it was locked
853 // out by the GC locker). So, right now, we'll ignore the return value.
854
855 do_full_collection(clear_all_soft_refs,
856 false /* do_maximal_compaction */);
857 }
858
859 bool G1CollectedHeap::upgrade_to_full_collection() {
860 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
861 log_info(gc, ergo)("Attempting full compaction clearing soft references");
862 bool success = do_full_collection(true /* clear_all_soft_refs */,
863 false /* do_maximal_compaction */);
864 // do_full_collection only fails if blocked by GC locker and that can't
865 // be the case here since we only call this when already completed one gc.
866 assert(success, "invariant");
867 return success;
868 }
869
870 void G1CollectedHeap::resize_heap_if_necessary() {
871 assert_at_safepoint_on_vm_thread();
872
873 bool should_expand;
874 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
875
876 if (resize_amount == 0) {
877 return;
878 } else if (should_expand) {
879 expand(resize_amount, _workers);
880 } else {
881 shrink(resize_amount);
882 }
883 }
884
885 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
886 bool do_gc,
887 bool maximal_compaction,
888 bool expect_null_mutator_alloc_region,
889 bool* gc_succeeded) {
890 *gc_succeeded = true;
891 // Let's attempt the allocation first.
892 HeapWord* result =
893 attempt_allocation_at_safepoint(word_size,
894 expect_null_mutator_alloc_region);
895 if (result != nullptr) {
896 return result;
897 }
898
899 // In a G1 heap, we're supposed to keep allocation from failing by
900 // incremental pauses. Therefore, at least for now, we'll favor
901 // expansion over collection. (This might change in the future if we can
902 // do something smarter than full collection to satisfy a failed alloc.)
903 result = expand_and_allocate(word_size);
904 if (result != nullptr) {
905 return result;
906 }
907
908 if (do_gc) {
909 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
910 // Expansion didn't work, we'll try to do a Full GC.
911 // If maximal_compaction is set we clear all soft references and don't
912 // allow any dead wood to be left on the heap.
913 if (maximal_compaction) {
914 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
915 } else {
916 log_info(gc, ergo)("Attempting full compaction");
917 }
918 *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ ,
919 maximal_compaction /* do_maximal_compaction */);
920 }
921
922 return nullptr;
923 }
924
925 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
926 bool* succeeded) {
927 assert_at_safepoint_on_vm_thread();
928
929 // Attempts to allocate followed by Full GC.
930 HeapWord* result =
931 satisfy_failed_allocation_helper(word_size,
932 true, /* do_gc */
933 false, /* maximum_collection */
934 false, /* expect_null_mutator_alloc_region */
935 succeeded);
936
937 if (result != nullptr || !*succeeded) {
938 return result;
939 }
940
941 // Attempts to allocate followed by Full GC that will collect all soft references.
942 result = satisfy_failed_allocation_helper(word_size,
943 true, /* do_gc */
944 true, /* maximum_collection */
945 true, /* expect_null_mutator_alloc_region */
946 succeeded);
947
948 if (result != nullptr || !*succeeded) {
949 return result;
950 }
951
952 // Attempts to allocate, no GC
953 result = satisfy_failed_allocation_helper(word_size,
954 false, /* do_gc */
955 false, /* maximum_collection */
956 true, /* expect_null_mutator_alloc_region */
957 succeeded);
958
959 if (result != nullptr) {
960 return result;
961 }
962
963 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
964 "Flag should have been handled and cleared prior to this point");
965
966 // What else? We might try synchronous finalization later. If the total
967 // space available is large enough for the allocation, then a more
968 // complete compaction phase than we've tried so far might be
969 // appropriate.
970 return nullptr;
971 }
972
973 // Attempting to expand the heap sufficiently
974 // to support an allocation of the given "word_size". If
975 // successful, perform the allocation and return the address of the
976 // allocated block, or else null.
977
978 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
979 assert_at_safepoint_on_vm_thread();
980
981 _verifier->verify_region_sets_optional();
982
983 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
984 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
985 word_size * HeapWordSize);
986
987
988 if (expand(expand_bytes, _workers)) {
989 _hrm.verify_optional();
990 _verifier->verify_region_sets_optional();
991 return attempt_allocation_at_safepoint(word_size,
992 false /* expect_null_mutator_alloc_region */);
993 }
994 return nullptr;
995 }
996
997 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
998 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
999 aligned_expand_bytes = align_up(aligned_expand_bytes,
1000 HeapRegion::GrainBytes);
1001
1002 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1003 expand_bytes, aligned_expand_bytes);
1004
1005 if (is_maximal_no_gc()) {
1006 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1007 return false;
1008 }
1009
1010 double expand_heap_start_time_sec = os::elapsedTime();
1011 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1012 assert(regions_to_expand > 0, "Must expand by at least one region");
1013
1014 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1015 if (expand_time_ms != nullptr) {
1016 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1017 }
1018
1019 assert(expanded_by > 0, "must have failed during commit.");
1020
1021 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1022 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1023 policy()->record_new_heap_size(num_regions());
1024
1025 return true;
1026 }
1027
1028 bool G1CollectedHeap::expand_single_region(uint node_index) {
1029 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1030
1031 if (expanded_by == 0) {
1032 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1033 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1034 return false;
1035 }
1036
1037 policy()->record_new_heap_size(num_regions());
1038 return true;
1039 }
1040
1041 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1042 size_t aligned_shrink_bytes =
1043 ReservedSpace::page_align_size_down(shrink_bytes);
1044 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1045 HeapRegion::GrainBytes);
1046 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1047
1048 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1049 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1050
1051 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",
1052 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1053 if (num_regions_removed > 0) {
1054 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1055 policy()->record_new_heap_size(num_regions());
1056 } else {
1057 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1058 }
1059 }
1060
1061 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1062 _verifier->verify_region_sets_optional();
1063
1064 // We should only reach here at the end of a Full GC or during Remark which
1065 // means we should not not be holding to any GC alloc regions. The method
1066 // below will make sure of that and do any remaining clean up.
1067 _allocator->abandon_gc_alloc_regions();
1068
1069 // Instead of tearing down / rebuilding the free lists here, we
1070 // could instead use the remove_all_pending() method on free_list to
1071 // remove only the ones that we need to remove.
1072 _hrm.remove_all_free_regions();
1073 shrink_helper(shrink_bytes);
1074 rebuild_region_sets(true /* free_list_only */);
1075
1076 _hrm.verify_optional();
1077 _verifier->verify_region_sets_optional();
1078 }
1079
1080 class OldRegionSetChecker : public HeapRegionSetChecker {
1081 public:
1082 void check_mt_safety() {
1083 // Master Old Set MT safety protocol:
1084 // (a) If we're at a safepoint, operations on the master old set
1085 // should be invoked:
1086 // - by the VM thread (which will serialize them), or
1087 // - by the GC workers while holding the FreeList_lock, if we're
1088 // at a safepoint for an evacuation pause (this lock is taken
1089 // anyway when an GC alloc region is retired so that a new one
1090 // is allocated from the free list), or
1091 // - by the GC workers while holding the OldSets_lock, if we're at a
1092 // safepoint for a cleanup pause.
1093 // (b) If we're not at a safepoint, operations on the master old set
1094 // should be invoked while holding the Heap_lock.
1095
1096 if (SafepointSynchronize::is_at_safepoint()) {
1097 guarantee(Thread::current()->is_VM_thread() ||
1098 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1099 "master old set MT safety protocol at a safepoint");
1100 } else {
1101 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1102 }
1103 }
1104 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1105 const char* get_description() { return "Old Regions"; }
1106 };
1107
1108 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1109 public:
1110 void check_mt_safety() {
1111 // Humongous Set MT safety protocol:
1112 // (a) If we're at a safepoint, operations on the master humongous
1113 // set should be invoked by either the VM thread (which will
1114 // serialize them) or by the GC workers while holding the
1115 // OldSets_lock.
1116 // (b) If we're not at a safepoint, operations on the master
1117 // humongous set should be invoked while holding the Heap_lock.
1118
1119 if (SafepointSynchronize::is_at_safepoint()) {
1120 guarantee(Thread::current()->is_VM_thread() ||
1121 OldSets_lock->owned_by_self(),
1122 "master humongous set MT safety protocol at a safepoint");
1123 } else {
1124 guarantee(Heap_lock->owned_by_self(),
1125 "master humongous set MT safety protocol outside a safepoint");
1126 }
1127 }
1128 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1129 const char* get_description() { return "Humongous Regions"; }
1130 };
1131
1132 G1CollectedHeap::G1CollectedHeap() :
1133 CollectedHeap(),
1134 _service_thread(nullptr),
1135 _periodic_gc_task(nullptr),
1136 _free_arena_memory_task(nullptr),
1137 _workers(nullptr),
1138 _card_table(nullptr),
1139 _collection_pause_end(Ticks::now()),
1140 _old_set("Old Region Set", new OldRegionSetChecker()),
1141 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1142 _bot(nullptr),
1143 _listener(),
1144 _numa(G1NUMA::create()),
1145 _hrm(),
1146 _allocator(nullptr),
1147 _allocation_failure_injector(),
1148 _verifier(nullptr),
1149 _summary_bytes_used(0),
1150 _bytes_used_during_gc(0),
1151 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1152 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1153 _monitoring_support(nullptr),
1154 _num_humongous_objects(0),
1155 _num_humongous_reclaim_candidates(0),
1156 _hr_printer(),
1157 _collector_state(),
1158 _old_marking_cycles_started(0),
1159 _old_marking_cycles_completed(0),
1160 _eden(),
1161 _survivor(),
1162 _gc_timer_stw(new STWGCTimer()),
1163 _gc_tracer_stw(new G1NewTracer()),
1164 _policy(new G1Policy(_gc_timer_stw)),
1165 _heap_sizing_policy(nullptr),
1166 _collection_set(this, _policy),
1167 _rem_set(nullptr),
1168 _card_set_config(),
1169 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1170 _cm(nullptr),
1171 _cm_thread(nullptr),
1172 _cr(nullptr),
1173 _task_queues(nullptr),
1174 _ref_processor_stw(nullptr),
1175 _is_alive_closure_stw(this),
1176 _is_subject_to_discovery_stw(this),
1177 _ref_processor_cm(nullptr),
1178 _is_alive_closure_cm(this),
1179 _is_subject_to_discovery_cm(this),
1180 _region_attr() {
1181
1182 _verifier = new G1HeapVerifier(this);
1183
1184 _allocator = new G1Allocator(this);
1185
1186 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1187
1188 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1189
1190 // Since filler arrays are never referenced, we can make them region sized.
1191 // This simplifies filling up the region in case we have some potentially
1192 // unreferenced (by Java code, but still in use by native code) pinned objects
1193 // in there.
1194 _filler_array_max_size = HeapRegion::GrainWords;
1195
1196 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1197 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1198
1199 uint n_queues = ParallelGCThreads;
1200 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1201
1202 for (uint i = 0; i < n_queues; i++) {
1203 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1204 _task_queues->register_queue(i, q);
1205 }
1206
1207 _gc_tracer_stw->initialize();
1208
1209 guarantee(_task_queues != nullptr, "task_queues allocation failure.");
1210 }
1211
1212 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1213 size_t size,
1214 size_t translation_factor) {
1215 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1216 // Allocate a new reserved space, preferring to use large pages.
1217 ReservedSpace rs(size, preferred_page_size);
1218 size_t page_size = rs.page_size();
1219 G1RegionToSpaceMapper* result =
1220 G1RegionToSpaceMapper::create_mapper(rs,
1221 size,
1222 page_size,
1223 HeapRegion::GrainBytes,
1224 translation_factor,
1225 mtGC);
1226
1227 os::trace_page_sizes_for_requested_size(description,
1228 size,
1229 preferred_page_size,
1230 rs.base(),
1231 rs.size(),
1232 page_size);
1233
1234 return result;
1235 }
1236
1237 jint G1CollectedHeap::initialize_concurrent_refinement() {
1238 jint ecode = JNI_OK;
1239 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1240 return ecode;
1241 }
1242
1243 jint G1CollectedHeap::initialize_service_thread() {
1244 _service_thread = new G1ServiceThread();
1245 if (_service_thread->osthread() == nullptr) {
1246 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1247 return JNI_ENOMEM;
1248 }
1249 return JNI_OK;
1250 }
1251
1252 jint G1CollectedHeap::initialize() {
1253
1254 // Necessary to satisfy locking discipline assertions.
1255
1256 MutexLocker x(Heap_lock);
1257
1258 // While there are no constraints in the GC code that HeapWordSize
1259 // be any particular value, there are multiple other areas in the
1260 // system which believe this to be true (e.g. oop->object_size in some
1261 // cases incorrectly returns the size in wordSize units rather than
1262 // HeapWordSize).
1263 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1264
1265 size_t init_byte_size = InitialHeapSize;
1266 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1267
1268 // Ensure that the sizes are properly aligned.
1269 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1270 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1271 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1272
1273 // Reserve the maximum.
1274
1275 // When compressed oops are enabled, the preferred heap base
1276 // is calculated by subtracting the requested size from the
1277 // 32Gb boundary and using the result as the base address for
1278 // heap reservation. If the requested size is not aligned to
1279 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1280 // into the ReservedHeapSpace constructor) then the actual
1281 // base of the reserved heap may end up differing from the
1282 // address that was requested (i.e. the preferred heap base).
1283 // If this happens then we could end up using a non-optimal
1284 // compressed oops mode.
1285
1286 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1287 HeapAlignment);
1288
1289 initialize_reserved_region(heap_rs);
1290
1291 // Create the barrier set for the entire reserved region.
1292 G1CardTable* ct = new G1CardTable(heap_rs.region());
1293 G1BarrierSet* bs = new G1BarrierSet(ct);
1294 bs->initialize();
1295 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1296 BarrierSet::set_barrier_set(bs);
1297 _card_table = ct;
1298
1299 {
1300 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1301 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1302 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1303 }
1304
1305 // Create space mappers.
1306 size_t page_size = heap_rs.page_size();
1307 G1RegionToSpaceMapper* heap_storage =
1308 G1RegionToSpaceMapper::create_mapper(heap_rs,
1309 heap_rs.size(),
1310 page_size,
1311 HeapRegion::GrainBytes,
1312 1,
1313 mtJavaHeap);
1314 if(heap_storage == nullptr) {
1315 vm_shutdown_during_initialization("Could not initialize G1 heap");
1316 return JNI_ERR;
1317 }
1318
1319 os::trace_page_sizes("Heap",
1320 MinHeapSize,
1321 reserved_byte_size,
1322 heap_rs.base(),
1323 heap_rs.size(),
1324 page_size);
1325 heap_storage->set_mapping_changed_listener(&_listener);
1326
1327 // Create storage for the BOT, card table and the bitmap.
1328 G1RegionToSpaceMapper* bot_storage =
1329 create_aux_memory_mapper("Block Offset Table",
1330 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1331 G1BlockOffsetTable::heap_map_factor());
1332
1333 G1RegionToSpaceMapper* cardtable_storage =
1334 create_aux_memory_mapper("Card Table",
1335 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1336 G1CardTable::heap_map_factor());
1337
1338 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1339 G1RegionToSpaceMapper* bitmap_storage =
1340 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1341
1342 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1343 _card_table->initialize(cardtable_storage);
1344
1345 // 6843694 - ensure that the maximum region index can fit
1346 // in the remembered set structures.
1347 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1348 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1349
1350 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1351 // start within the first card.
1352 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1353 G1FromCardCache::initialize(max_reserved_regions());
1354 // Also create a G1 rem set.
1355 _rem_set = new G1RemSet(this, _card_table);
1356 _rem_set->initialize(max_reserved_regions());
1357
1358 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1359 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1360 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1361 "too many cards per region");
1362
1363 HeapRegionRemSet::initialize(_reserved);
1364
1365 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1366
1367 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1368
1369 {
1370 size_t granularity = HeapRegion::GrainBytes;
1371
1372 _region_attr.initialize(reserved(), granularity);
1373 }
1374
1375 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1376 if (_workers == nullptr) {
1377 return JNI_ENOMEM;
1378 }
1379 _workers->initialize_workers();
1380
1381 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1382
1383 // Create the G1ConcurrentMark data structure and thread.
1384 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1385 _cm = new G1ConcurrentMark(this, bitmap_storage);
1386 _cm_thread = _cm->cm_thread();
1387
1388 // Now expand into the initial heap size.
1389 if (!expand(init_byte_size, _workers)) {
1390 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1391 return JNI_ENOMEM;
1392 }
1393
1394 // Perform any initialization actions delegated to the policy.
1395 policy()->init(this, &_collection_set);
1396
1397 jint ecode = initialize_concurrent_refinement();
1398 if (ecode != JNI_OK) {
1399 return ecode;
1400 }
1401
1402 ecode = initialize_service_thread();
1403 if (ecode != JNI_OK) {
1404 return ecode;
1405 }
1406
1407 // Create and schedule the periodic gc task on the service thread.
1408 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1409 _service_thread->register_task(_periodic_gc_task);
1410
1411 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1412 _service_thread->register_task(_free_arena_memory_task);
1413
1414 // Here we allocate the dummy HeapRegion that is required by the
1415 // G1AllocRegion class.
1416 HeapRegion* dummy_region = _hrm.get_dummy_region();
1417
1418 // We'll re-use the same region whether the alloc region will
1419 // require BOT updates or not and, if it doesn't, then a non-young
1420 // region will complain that it cannot support allocations without
1421 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1422 dummy_region->set_eden();
1423 // Make sure it's full.
1424 dummy_region->set_top(dummy_region->end());
1425 G1AllocRegion::setup(this, dummy_region);
1426
1427 _allocator->init_mutator_alloc_regions();
1428
1429 // Do create of the monitoring and management support so that
1430 // values in the heap have been properly initialized.
1431 _monitoring_support = new G1MonitoringSupport(this);
1432
1433 _collection_set.initialize(max_reserved_regions());
1434
1435 allocation_failure_injector()->reset();
1436
1437 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_parallel_workers);
1438 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_conc_mark);
1439 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_conc_refine);
1440 CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_service);
1441
1442 G1InitLogger::print();
1443
1444 SlidingForwarding::initialize(heap_rs.region(), HeapRegion::GrainWords);
1445
1446 return JNI_OK;
1447 }
1448
1449 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1450 return _cm_thread->should_terminate();
1451 }
1452
1453 void G1CollectedHeap::stop() {
1454 // Stop all concurrent threads. We do this to make sure these threads
1455 // do not continue to execute and access resources (e.g. logging)
1456 // that are destroyed during shutdown.
1457 _cr->stop();
1458 _service_thread->stop();
1459 _cm_thread->stop();
1460 }
1461
1462 void G1CollectedHeap::safepoint_synchronize_begin() {
1463 SuspendibleThreadSet::synchronize();
1464 }
1465
1466 void G1CollectedHeap::safepoint_synchronize_end() {
1467 SuspendibleThreadSet::desynchronize();
1468 }
1469
1470 void G1CollectedHeap::post_initialize() {
1471 CollectedHeap::post_initialize();
1472 ref_processing_init();
1473 }
1474
1475 void G1CollectedHeap::ref_processing_init() {
1476 // Reference processing in G1 currently works as follows:
1477 //
1478 // * There are two reference processor instances. One is
1479 // used to record and process discovered references
1480 // during concurrent marking; the other is used to
1481 // record and process references during STW pauses
1482 // (both full and incremental).
1483 // * Both ref processors need to 'span' the entire heap as
1484 // the regions in the collection set may be dotted around.
1485 //
1486 // * For the concurrent marking ref processor:
1487 // * Reference discovery is enabled at concurrent start.
1488 // * Reference discovery is disabled and the discovered
1489 // references processed etc during remarking.
1490 // * Reference discovery is MT (see below).
1491 // * Reference discovery requires a barrier (see below).
1492 // * Reference processing may or may not be MT
1493 // (depending on the value of ParallelRefProcEnabled
1494 // and ParallelGCThreads).
1495 // * A full GC disables reference discovery by the CM
1496 // ref processor and abandons any entries on it's
1497 // discovered lists.
1498 //
1499 // * For the STW processor:
1500 // * Non MT discovery is enabled at the start of a full GC.
1501 // * Processing and enqueueing during a full GC is non-MT.
1502 // * During a full GC, references are processed after marking.
1503 //
1504 // * Discovery (may or may not be MT) is enabled at the start
1505 // of an incremental evacuation pause.
1506 // * References are processed near the end of a STW evacuation pause.
1507 // * For both types of GC:
1508 // * Discovery is atomic - i.e. not concurrent.
1509 // * Reference discovery will not need a barrier.
1510
1511 // Concurrent Mark ref processor
1512 _ref_processor_cm =
1513 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1514 ParallelGCThreads, // degree of mt processing
1515 // We discover with the gc worker threads during Remark, so both
1516 // thread counts must be considered for discovery.
1517 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1518 true, // Reference discovery is concurrent
1519 &_is_alive_closure_cm); // is alive closure
1520
1521 // STW ref processor
1522 _ref_processor_stw =
1523 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1524 ParallelGCThreads, // degree of mt processing
1525 ParallelGCThreads, // degree of mt discovery
1526 false, // Reference discovery is not concurrent
1527 &_is_alive_closure_stw); // is alive closure
1528 }
1529
1530 size_t G1CollectedHeap::capacity() const {
1531 return _hrm.length() * HeapRegion::GrainBytes;
1532 }
1533
1534 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1535 return _hrm.total_free_bytes();
1536 }
1537
1538 // Computes the sum of the storage used by the various regions.
1539 size_t G1CollectedHeap::used() const {
1540 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1541 return result;
1542 }
1543
1544 size_t G1CollectedHeap::used_unlocked() const {
1545 return _summary_bytes_used;
1546 }
1547
1548 class SumUsedClosure: public HeapRegionClosure {
1549 size_t _used;
1550 public:
1551 SumUsedClosure() : _used(0) {}
1552 bool do_heap_region(HeapRegion* r) {
1553 _used += r->used();
1554 return false;
1555 }
1556 size_t result() { return _used; }
1557 };
1558
1559 size_t G1CollectedHeap::recalculate_used() const {
1560 SumUsedClosure blk;
1561 heap_region_iterate(&blk);
1562 return blk.result();
1563 }
1564
1565 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1566 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1567 }
1568
1569 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1570 switch (cause) {
1571 case GCCause::_g1_humongous_allocation: return true;
1572 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1573 case GCCause::_wb_breakpoint: return true;
1574 case GCCause::_codecache_GC_aggressive: return true;
1575 case GCCause::_codecache_GC_threshold: return true;
1576 default: return is_user_requested_concurrent_full_gc(cause);
1577 }
1578 }
1579
1580 void G1CollectedHeap::increment_old_marking_cycles_started() {
1581 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1582 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1583 "Wrong marking cycle count (started: %d, completed: %d)",
1584 _old_marking_cycles_started, _old_marking_cycles_completed);
1585
1586 _old_marking_cycles_started++;
1587 }
1588
1589 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1590 bool whole_heap_examined) {
1591 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1592
1593 // We assume that if concurrent == true, then the caller is a
1594 // concurrent thread that was joined the Suspendible Thread
1595 // Set. If there's ever a cheap way to check this, we should add an
1596 // assert here.
1597
1598 // Given that this method is called at the end of a Full GC or of a
1599 // concurrent cycle, and those can be nested (i.e., a Full GC can
1600 // interrupt a concurrent cycle), the number of full collections
1601 // completed should be either one (in the case where there was no
1602 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1603 // behind the number of full collections started.
1604
1605 // This is the case for the inner caller, i.e. a Full GC.
1606 assert(concurrent ||
1607 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1608 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1609 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1610 "is inconsistent with _old_marking_cycles_completed = %u",
1611 _old_marking_cycles_started, _old_marking_cycles_completed);
1612
1613 // This is the case for the outer caller, i.e. the concurrent cycle.
1614 assert(!concurrent ||
1615 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1616 "for outer caller (concurrent cycle): "
1617 "_old_marking_cycles_started = %u "
1618 "is inconsistent with _old_marking_cycles_completed = %u",
1619 _old_marking_cycles_started, _old_marking_cycles_completed);
1620
1621 _old_marking_cycles_completed += 1;
1622 if (whole_heap_examined) {
1623 // Signal that we have completed a visit to all live objects.
1624 record_whole_heap_examined_timestamp();
1625 }
1626
1627 // We need to clear the "in_progress" flag in the CM thread before
1628 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1629 // is set) so that if a waiter requests another System.gc() it doesn't
1630 // incorrectly see that a marking cycle is still in progress.
1631 if (concurrent) {
1632 _cm_thread->set_idle();
1633 }
1634
1635 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1636 // for a full GC to finish that their wait is over.
1637 ml.notify_all();
1638 }
1639
1640 // Helper for collect().
1641 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1642 MutexLocker ml(Heap_lock);
1643 return G1GCCounters(g1h);
1644 }
1645
1646 void G1CollectedHeap::collect(GCCause::Cause cause) {
1647 try_collect(cause, collection_counters(this));
1648 }
1649
1650 // Return true if (x < y) with allowance for wraparound.
1651 static bool gc_counter_less_than(uint x, uint y) {
1652 return (x - y) > (UINT_MAX/2);
1653 }
1654
1655 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1656 // Macro so msg printing is format-checked.
1657 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1658 do { \
1659 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1660 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1661 ResourceMark rm; /* For thread name. */ \
1662 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1663 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1664 Thread::current()->name(), \
1665 GCCause::to_string(cause)); \
1666 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1667 } \
1668 } while (0)
1669
1670 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1671 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1672
1673 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1674 uint gc_counter,
1675 uint old_marking_started_before) {
1676 assert_heap_not_locked();
1677 assert(should_do_concurrent_full_gc(cause),
1678 "Non-concurrent cause %s", GCCause::to_string(cause));
1679
1680 for (uint i = 1; true; ++i) {
1681 // Try to schedule concurrent start evacuation pause that will
1682 // start a concurrent cycle.
1683 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1684 VM_G1TryInitiateConcMark op(gc_counter, cause);
1685 VMThread::execute(&op);
1686
1687 // Request is trivially finished.
1688 if (cause == GCCause::_g1_periodic_collection) {
1689 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1690 return op.gc_succeeded();
1691 }
1692
1693 // If VMOp skipped initiating concurrent marking cycle because
1694 // we're terminating, then we're done.
1695 if (op.terminating()) {
1696 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1697 return false;
1698 }
1699
1700 // Lock to get consistent set of values.
1701 uint old_marking_started_after;
1702 uint old_marking_completed_after;
1703 {
1704 MutexLocker ml(Heap_lock);
1705 // Update gc_counter for retrying VMOp if needed. Captured here to be
1706 // consistent with the values we use below for termination tests. If
1707 // a retry is needed after a possible wait, and another collection
1708 // occurs in the meantime, it will cause our retry to be skipped and
1709 // we'll recheck for termination with updated conditions from that
1710 // more recent collection. That's what we want, rather than having
1711 // our retry possibly perform an unnecessary collection.
1712 gc_counter = total_collections();
1713 old_marking_started_after = _old_marking_cycles_started;
1714 old_marking_completed_after = _old_marking_cycles_completed;
1715 }
1716
1717 if (cause == GCCause::_wb_breakpoint) {
1718 if (op.gc_succeeded()) {
1719 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1720 return true;
1721 }
1722 // When _wb_breakpoint there can't be another cycle or deferred.
1723 assert(!op.cycle_already_in_progress(), "invariant");
1724 assert(!op.whitebox_attached(), "invariant");
1725 // Concurrent cycle attempt might have been cancelled by some other
1726 // collection, so retry. Unlike other cases below, we want to retry
1727 // even if cancelled by a STW full collection, because we really want
1728 // to start a concurrent cycle.
1729 if (old_marking_started_before != old_marking_started_after) {
1730 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1731 old_marking_started_before = old_marking_started_after;
1732 }
1733 } else if (!GCCause::is_user_requested_gc(cause)) {
1734 // For an "automatic" (not user-requested) collection, we just need to
1735 // ensure that progress is made.
1736 //
1737 // Request is finished if any of
1738 // (1) the VMOp successfully performed a GC,
1739 // (2) a concurrent cycle was already in progress,
1740 // (3) whitebox is controlling concurrent cycles,
1741 // (4) a new cycle was started (by this thread or some other), or
1742 // (5) a Full GC was performed.
1743 // Cases (4) and (5) are detected together by a change to
1744 // _old_marking_cycles_started.
1745 //
1746 // Note that (1) does not imply (4). If we're still in the mixed
1747 // phase of an earlier concurrent collection, the request to make the
1748 // collection a concurrent start won't be honored. If we don't check for
1749 // both conditions we'll spin doing back-to-back collections.
1750 if (op.gc_succeeded() ||
1751 op.cycle_already_in_progress() ||
1752 op.whitebox_attached() ||
1753 (old_marking_started_before != old_marking_started_after)) {
1754 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1755 return true;
1756 }
1757 } else { // User-requested GC.
1758 // For a user-requested collection, we want to ensure that a complete
1759 // full collection has been performed before returning, but without
1760 // waiting for more than needed.
1761
1762 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1763 // new cycle was started. That's good, because it's not clear what we
1764 // should do otherwise. Trying again just does back to back GCs.
1765 // Can't wait for someone else to start a cycle. And returning fails
1766 // to meet the goal of ensuring a full collection was performed.
1767 assert(!op.gc_succeeded() ||
1768 (old_marking_started_before != old_marking_started_after),
1769 "invariant: succeeded %s, started before %u, started after %u",
1770 BOOL_TO_STR(op.gc_succeeded()),
1771 old_marking_started_before, old_marking_started_after);
1772
1773 // Request is finished if a full collection (concurrent or stw)
1774 // was started after this request and has completed, e.g.
1775 // started_before < completed_after.
1776 if (gc_counter_less_than(old_marking_started_before,
1777 old_marking_completed_after)) {
1778 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1779 return true;
1780 }
1781
1782 if (old_marking_started_after != old_marking_completed_after) {
1783 // If there is an in-progress cycle (possibly started by us), then
1784 // wait for that cycle to complete, e.g.
1785 // while completed_now < started_after.
1786 LOG_COLLECT_CONCURRENTLY(cause, "wait");
1787 MonitorLocker ml(G1OldGCCount_lock);
1788 while (gc_counter_less_than(_old_marking_cycles_completed,
1789 old_marking_started_after)) {
1790 ml.wait();
1791 }
1792 // Request is finished if the collection we just waited for was
1793 // started after this request.
1794 if (old_marking_started_before != old_marking_started_after) {
1795 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
1796 return true;
1797 }
1798 }
1799
1800 // If VMOp was successful then it started a new cycle that the above
1801 // wait &etc should have recognized as finishing this request. This
1802 // differs from a non-user-request, where gc_succeeded does not imply
1803 // a new cycle was started.
1804 assert(!op.gc_succeeded(), "invariant");
1805
1806 if (op.cycle_already_in_progress()) {
1807 // If VMOp failed because a cycle was already in progress, it
1808 // is now complete. But it didn't finish this user-requested
1809 // GC, so try again.
1810 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
1811 continue;
1812 } else if (op.whitebox_attached()) {
1813 // If WhiteBox wants control, wait for notification of a state
1814 // change in the controller, then try again. Don't wait for
1815 // release of control, since collections may complete while in
1816 // control. Note: This won't recognize a STW full collection
1817 // while waiting; we can't wait on multiple monitors.
1818 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
1819 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
1820 if (ConcurrentGCBreakpoints::is_controlled()) {
1821 ml.wait();
1822 }
1823 continue;
1824 }
1825 }
1826
1827 // Collection failed and should be retried.
1828 assert(op.transient_failure(), "invariant");
1829
1830 LOG_COLLECT_CONCURRENTLY(cause, "retry");
1831 }
1832 }
1833
1834 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause,
1835 const G1GCCounters& counters_before) {
1836 assert_heap_not_locked();
1837
1838 while(true) {
1839 VM_G1CollectFull op(counters_before.total_collections(),
1840 counters_before.total_full_collections(),
1841 cause);
1842 VMThread::execute(&op);
1843
1844 // Request is trivially finished.
1845 if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) {
1846 return op.gc_succeeded();
1847 }
1848
1849 {
1850 MutexLocker ml(Heap_lock);
1851 if (counters_before.total_full_collections() != total_full_collections()) {
1852 return true;
1853 }
1854 }
1855 }
1856 }
1857
1858 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
1859 const G1GCCounters& counters_before) {
1860 if (should_do_concurrent_full_gc(cause)) {
1861 return try_collect_concurrently(cause,
1862 counters_before.total_collections(),
1863 counters_before.old_marking_cycles_started());
1864 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
1865 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1866
1867 // Schedule a standard evacuation pause. We're setting word_size
1868 // to 0 which means that we are not requesting a post-GC allocation.
1869 VM_G1CollectForAllocation op(0, /* word_size */
1870 counters_before.total_collections(),
1871 cause);
1872 VMThread::execute(&op);
1873 return op.gc_succeeded();
1874 } else {
1875 // Schedule a Full GC.
1876 return try_collect_fullgc(cause, counters_before);
1877 }
1878 }
1879
1880 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
1881 GCCauseSetter x(this, gc_cause);
1882
1883 // At this point we are supposed to start a concurrent cycle. We
1884 // will do so if one is not already in progress.
1885 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
1886 if (should_start) {
1887 do_collection_pause_at_safepoint();
1888 }
1889 }
1890
1891 bool G1CollectedHeap::is_in(const void* p) const {
1892 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
1893 }
1894
1895 // Iteration functions.
1896
1897 // Iterates an ObjectClosure over all objects within a HeapRegion.
1898
1899 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1900 ObjectClosure* _cl;
1901 public:
1902 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1903 bool do_heap_region(HeapRegion* r) {
1904 if (!r->is_continues_humongous()) {
1905 r->object_iterate(_cl);
1906 }
1907 return false;
1908 }
1909 };
1910
1911 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
1912 IterateObjectClosureRegionClosure blk(cl);
1913 heap_region_iterate(&blk);
1914 }
1915
1916 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
1917 private:
1918 G1CollectedHeap* _heap;
1919 HeapRegionClaimer _claimer;
1920
1921 public:
1922 G1ParallelObjectIterator(uint thread_num) :
1923 _heap(G1CollectedHeap::heap()),
1924 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
1925
1926 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1927 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
1928 }
1929 };
1930
1931 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
1932 return new G1ParallelObjectIterator(thread_num);
1933 }
1934
1935 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
1936 IterateObjectClosureRegionClosure blk(cl);
1937 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
1938 }
1939
1940 void G1CollectedHeap::keep_alive(oop obj) {
1941 G1BarrierSet::enqueue_preloaded(obj);
1942 }
1943
1944 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
1945 _hrm.iterate(cl);
1946 }
1947
1948 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
1949 _hrm.iterate(cl);
1950 }
1951
1952 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1953 HeapRegionClaimer *hrclaimer,
1954 uint worker_id) const {
1955 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
1956 }
1957
1958 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1959 HeapRegionClaimer *hrclaimer) const {
1960 _hrm.par_iterate(cl, hrclaimer, 0);
1961 }
1962
1963 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
1964 _collection_set.iterate(cl);
1965 }
1966
1967 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
1968 HeapRegionClaimer* hr_claimer,
1969 uint worker_id) {
1970 _collection_set.par_iterate(cl, hr_claimer, worker_id);
1971 }
1972
1973 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
1974 HeapRegionClaimer* hr_claimer,
1975 uint worker_id) {
1976 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
1977 }
1978
1979 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
1980 HeapRegionClaimer* hr_claimer,
1981 const uint regions[],
1982 size_t length,
1983 uint worker_id) const {
1984 assert_at_safepoint();
1985 if (length == 0) {
1986 return;
1987 }
1988 uint total_workers = workers()->active_workers();
1989
1990 size_t start_pos = (worker_id * length) / total_workers;
1991 size_t cur_pos = start_pos;
1992
1993 do {
1994 uint region_idx = regions[cur_pos];
1995 if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) {
1996 HeapRegion* r = region_at(region_idx);
1997 bool result = cl->do_heap_region(r);
1998 guarantee(!result, "Must not cancel iteration");
1999 }
2000
2001 cur_pos++;
2002 if (cur_pos == length) {
2003 cur_pos = 0;
2004 }
2005 } while (cur_pos != start_pos);
2006 }
2007
2008 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2009 HeapRegion* hr = heap_region_containing(addr);
2010 // The CollectedHeap API requires us to not fail for any given address within
2011 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2012 // outside of the allocated area.
2013 if (addr >= hr->top()) {
2014 return nullptr;
2015 }
2016 return hr->block_start(addr);
2017 }
2018
2019 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2020 HeapRegion* hr = heap_region_containing(addr);
2021 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2022 }
2023
2024 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2025 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2026 }
2027
2028 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2029 return _eden.length() * HeapRegion::GrainBytes;
2030 }
2031
2032 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2033 // must be equal to the humongous object limit.
2034 size_t G1CollectedHeap::max_tlab_size() const {
2035 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2036 }
2037
2038 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2039 return _allocator->unsafe_max_tlab_alloc();
2040 }
2041
2042 size_t G1CollectedHeap::max_capacity() const {
2043 return max_regions() * HeapRegion::GrainBytes;
2044 }
2045
2046 void G1CollectedHeap::prepare_for_verify() {
2047 _verifier->prepare_for_verify();
2048 }
2049
2050 void G1CollectedHeap::verify(VerifyOption vo) {
2051 _verifier->verify(vo);
2052 }
2053
2054 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2055 return true;
2056 }
2057
2058 class PrintRegionClosure: public HeapRegionClosure {
2059 outputStream* _st;
2060 public:
2061 PrintRegionClosure(outputStream* st) : _st(st) {}
2062 bool do_heap_region(HeapRegion* r) {
2063 r->print_on(_st);
2064 return false;
2065 }
2066 };
2067
2068 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2069 const HeapRegion* hr,
2070 const VerifyOption vo) const {
2071 switch (vo) {
2072 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2073 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2074 default: ShouldNotReachHere();
2075 }
2076 return false; // keep some compilers happy
2077 }
2078
2079 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2080 const VerifyOption vo) const {
2081 switch (vo) {
2082 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2083 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2084 default: ShouldNotReachHere();
2085 }
2086 return false; // keep some compilers happy
2087 }
2088
2089 void G1CollectedHeap::print_heap_regions() const {
2090 LogTarget(Trace, gc, heap, region) lt;
2091 if (lt.is_enabled()) {
2092 LogStream ls(lt);
2093 print_regions_on(&ls);
2094 }
2095 }
2096
2097 void G1CollectedHeap::print_on(outputStream* st) const {
2098 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2099 st->print(" %-20s", "garbage-first heap");
2100 st->print(" total reserved %zuK, committed %zuK, used %zuK",
2101 _hrm.reserved().byte_size()/K, capacity()/K, heap_used/K);
2102 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2103 p2i(_hrm.reserved().start()),
2104 p2i(_hrm.reserved().end()));
2105 st->cr();
2106 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2107 uint young_regions = young_regions_count();
2108 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2109 (size_t) young_regions * HeapRegion::GrainBytes / K);
2110 uint survivor_regions = survivor_regions_count();
2111 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2112 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2113 st->cr();
2114 if (_numa->is_enabled()) {
2115 uint num_nodes = _numa->num_active_nodes();
2116 st->print(" remaining free region(s) on each NUMA node: ");
2117 const uint* node_ids = _numa->node_ids();
2118 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2119 uint num_free_regions = _hrm.num_free_regions(node_index);
2120 st->print("%u=%u ", node_ids[node_index], num_free_regions);
2121 }
2122 st->cr();
2123 }
2124 MetaspaceUtils::print_on(st);
2125 }
2126
2127 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2128 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2129 "HS=humongous(starts), HC=humongous(continues), "
2130 "CS=collection set, F=free, "
2131 "TAMS=top-at-mark-start, "
2132 "PB=parsable bottom");
2133 PrintRegionClosure blk(st);
2134 heap_region_iterate(&blk);
2135 }
2136
2137 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2138 print_on(st);
2139
2140 // Print the per-region information.
2141 st->cr();
2142 print_regions_on(st);
2143 }
2144
2145 void G1CollectedHeap::print_on_error(outputStream* st) const {
2146 this->CollectedHeap::print_on_error(st);
2147
2148 if (_cm != nullptr) {
2149 st->cr();
2150 _cm->print_on_error(st);
2151 }
2152 }
2153
2154 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2155 workers()->threads_do(tc);
2156 tc->do_thread(_cm_thread);
2157 _cm->threads_do(tc);
2158 _cr->threads_do(tc);
2159 tc->do_thread(_service_thread);
2160 }
2161
2162 void G1CollectedHeap::print_tracing_info() const {
2163 rem_set()->print_summary_info();
2164 concurrent_mark()->print_summary_info();
2165 }
2166
2167 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2168 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2169 }
2170
2171 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2172
2173 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2174 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2175 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2176 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2177
2178 size_t eden_capacity_bytes =
2179 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2180
2181 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2182 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2183 survivor_used_bytes, old_gen_used_bytes, num_regions());
2184 }
2185
2186 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2187 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2188 stats->unused(), stats->used(), stats->region_end_waste(),
2189 stats->regions_filled(), stats->num_plab_filled(),
2190 stats->direct_allocated(), stats->num_direct_allocated(),
2191 stats->failure_used(), stats->failure_waste());
2192 }
2193
2194 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2195 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2196 gc_tracer->report_gc_heap_summary(when, heap_summary);
2197
2198 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2199 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2200 }
2201
2202 void G1CollectedHeap::gc_prologue(bool full) {
2203 // Update common counters.
2204 increment_total_collections(full /* full gc */);
2205 if (full || collector_state()->in_concurrent_start_gc()) {
2206 increment_old_marking_cycles_started();
2207 }
2208 }
2209
2210 void G1CollectedHeap::gc_epilogue(bool full) {
2211 // Update common counters.
2212 if (full) {
2213 // Update the number of full collections that have been completed.
2214 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2215 }
2216
2217 #if COMPILER2_OR_JVMCI
2218 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2219 #endif
2220
2221 // We have just completed a GC. Update the soft reference
2222 // policy with the new heap occupancy
2223 Universe::heap()->update_capacity_and_used_at_gc();
2224
2225 _collection_pause_end = Ticks::now();
2226
2227 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2228 &_collection_set_candidates_card_set_stats);
2229
2230 update_parallel_gc_threads_cpu_time();
2231 }
2232
2233 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2234 return _hrm.uncommit_inactive_regions(region_limit);
2235 }
2236
2237 bool G1CollectedHeap::has_uncommittable_regions() {
2238 return _hrm.has_inactive_regions();
2239 }
2240
2241 void G1CollectedHeap::uncommit_regions_if_necessary() {
2242 if (has_uncommittable_regions()) {
2243 G1UncommitRegionTask::enqueue();
2244 }
2245 }
2246
2247 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2248 LogTarget(Trace, gc, heap, verify) lt;
2249
2250 if (lt.is_enabled()) {
2251 LogStream ls(lt);
2252 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2253 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2254 heap_region_iterate(&cl);
2255 }
2256 }
2257
2258 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2259 uint gc_count_before,
2260 bool* succeeded,
2261 GCCause::Cause gc_cause) {
2262 assert_heap_not_locked_and_not_at_safepoint();
2263 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2264 VMThread::execute(&op);
2265
2266 HeapWord* result = op.result();
2267 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2268 assert(result == nullptr || ret_succeeded,
2269 "the result should be null if the VM did not succeed");
2270 *succeeded = ret_succeeded;
2271
2272 assert_heap_not_locked();
2273 return result;
2274 }
2275
2276 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2277 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2278
2279 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2280 if (concurrent_operation_is_full_mark) {
2281 _cm->post_concurrent_mark_start();
2282 _cm_thread->start_full_mark();
2283 } else {
2284 _cm->post_concurrent_undo_start();
2285 _cm_thread->start_undo_mark();
2286 }
2287 CGC_lock->notify();
2288 }
2289
2290 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2291 // We don't nominate objects with many remembered set entries, on
2292 // the assumption that such objects are likely still live.
2293 HeapRegionRemSet* rem_set = r->rem_set();
2294
2295 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2296 }
2297
2298 #ifndef PRODUCT
2299 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2300 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2301 public:
2302 virtual bool do_heap_region(HeapRegion* r) {
2303 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2304 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2305 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2306 "Region %u remset tracking status (%s) different to region attribute (%s)",
2307 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2308 return false;
2309 }
2310 } cl;
2311 heap_region_iterate(&cl);
2312 }
2313 #endif
2314
2315 void G1CollectedHeap::update_parallel_gc_threads_cpu_time() {
2316 assert(Thread::current()->is_VM_thread(),
2317 "Must be called from VM thread to avoid races");
2318 if (!UsePerfData || !os::is_thread_cpu_time_supported()) {
2319 return;
2320 }
2321
2322 // Ensure ThreadTotalCPUTimeClosure destructor is called before publishing gc
2323 // time.
2324 {
2325 ThreadTotalCPUTimeClosure tttc(CPUTimeGroups::CPUTimeType::gc_parallel_workers);
2326 // Currently parallel worker threads never terminate (JDK-8081682), so it is
2327 // safe for VMThread to read their CPU times. However, if JDK-8087340 is
2328 // resolved so they terminate, we should rethink if it is still safe.
2329 workers()->threads_do(&tttc);
2330 }
2331
2332 CPUTimeCounters::publish_gc_total_cpu_time();
2333 }
2334
2335 void G1CollectedHeap::start_new_collection_set() {
2336 collection_set()->start_incremental_building();
2337
2338 clear_region_attr();
2339
2340 guarantee(_eden.length() == 0, "eden should have been cleared");
2341 policy()->transfer_survivors_to_cset(survivor());
2342
2343 // We redo the verification but now wrt to the new CSet which
2344 // has just got initialized after the previous CSet was freed.
2345 _cm->verify_no_collection_set_oops();
2346 }
2347
2348 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2349 if (collector_state()->in_concurrent_start_gc()) {
2350 return G1HeapVerifier::G1VerifyConcurrentStart;
2351 } else if (collector_state()->in_young_only_phase()) {
2352 return G1HeapVerifier::G1VerifyYoungNormal;
2353 } else {
2354 return G1HeapVerifier::G1VerifyMixed;
2355 }
2356 }
2357
2358 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2359 if (!VerifyBeforeGC) {
2360 return;
2361 }
2362 if (!G1HeapVerifier::should_verify(type)) {
2363 return;
2364 }
2365 Ticks start = Ticks::now();
2366 _verifier->prepare_for_verify();
2367 _verifier->verify_region_sets_optional();
2368 _verifier->verify_dirty_young_regions();
2369 _verifier->verify_before_gc();
2370 verify_numa_regions("GC Start");
2371 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2372 }
2373
2374 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2375 if (!VerifyAfterGC) {
2376 return;
2377 }
2378 if (!G1HeapVerifier::should_verify(type)) {
2379 return;
2380 }
2381 Ticks start = Ticks::now();
2382 _verifier->verify_after_gc();
2383 verify_numa_regions("GC End");
2384 _verifier->verify_region_sets_optional();
2385
2386 if (collector_state()->in_concurrent_start_gc()) {
2387 log_debug(gc, verify)("Marking state");
2388 _verifier->verify_marking_state();
2389 }
2390
2391 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2392 }
2393
2394 void G1CollectedHeap::expand_heap_after_young_collection(){
2395 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2396 if (expand_bytes > 0) {
2397 // No need for an ergo logging here,
2398 // expansion_amount() does this when it returns a value > 0.
2399 double expand_ms = 0.0;
2400 if (!expand(expand_bytes, _workers, &expand_ms)) {
2401 // We failed to expand the heap. Cannot do anything about it.
2402 }
2403 phase_times()->record_expand_heap_time(expand_ms);
2404 }
2405 }
2406
2407 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2408 assert_at_safepoint_on_vm_thread();
2409 guarantee(!is_gc_active(), "collection is not reentrant");
2410
2411 do_collection_pause_at_safepoint_helper();
2412 return true;
2413 }
2414
2415 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2416 // This summary needs to be printed before incrementing total collections.
2417 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2418 _g1h->total_collections(),
2419 true /* show_thread_times */);
2420 _g1h->print_heap_before_gc();
2421 _g1h->print_heap_regions();
2422 }
2423
2424 G1HeapPrinterMark::~G1HeapPrinterMark() {
2425 _g1h->policy()->print_age_table();
2426 _g1h->rem_set()->print_coarsen_stats();
2427 // We are at the end of the GC. Total collections has already been increased.
2428 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2429 _g1h->total_collections() - 1,
2430 false /* show_thread_times */);
2431
2432 _heap_transition.print();
2433 _g1h->print_heap_regions();
2434 _g1h->print_heap_after_gc();
2435 // Print NUMA statistics.
2436 _g1h->numa()->print_statistics();
2437 }
2438
2439 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2440 _timer(timer), _tracer(tracer) {
2441
2442 _timer->register_gc_start();
2443 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2444 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2445 }
2446
2447 G1JFRTracerMark::~G1JFRTracerMark() {
2448 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2449 _timer->register_gc_end();
2450 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2451 }
2452
2453 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2454 Ticks start = Ticks::now();
2455
2456 _survivor_evac_stats.adjust_desired_plab_size();
2457 _old_evac_stats.adjust_desired_plab_size();
2458
2459 // Start a new incremental collection set for the mutator phase.
2460 start_new_collection_set();
2461 _allocator->init_mutator_alloc_regions();
2462
2463 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2464 }
2465
2466 void G1CollectedHeap::retire_tlabs() {
2467 ensure_parsability(true);
2468 }
2469
2470 void G1CollectedHeap::flush_region_pin_cache() {
2471 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
2472 G1ThreadLocalData::pin_count_cache(thread).flush();
2473 }
2474 }
2475
2476 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2477 ResourceMark rm;
2478
2479 IsGCActiveMark active_gc_mark;
2480 GCIdMark gc_id_mark;
2481 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2482
2483 GCTraceCPUTime tcpu(_gc_tracer_stw);
2484
2485 _bytes_used_during_gc = 0;
2486
2487 policy()->decide_on_concurrent_start_pause();
2488 // Record whether this pause may need to trigger a concurrent operation. Later,
2489 // when we signal the G1ConcurrentMarkThread, the collector state has already
2490 // been reset for the next pause.
2491 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2492
2493 // Perform the collection.
2494 G1YoungCollector collector(gc_cause());
2495 collector.collect();
2496
2497 // It should now be safe to tell the concurrent mark thread to start
2498 // without its logging output interfering with the logging output
2499 // that came from the pause.
2500 if (should_start_concurrent_mark_operation) {
2501 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2502 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2503 // thread(s) could be running concurrently with us. Make sure that anything
2504 // after this point does not assume that we are the only GC thread running.
2505 // Note: of course, the actual marking work will not start until the safepoint
2506 // itself is released in SuspendibleThreadSet::desynchronize().
2507 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2508 ConcurrentGCBreakpoints::notify_idle_to_active();
2509 }
2510 }
2511
2512 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2513 uint num_workers = workers()->active_workers();
2514 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2515 workers()->run_task(&unlink_task);
2516 }
2517
2518 void G1CollectedHeap::unload_classes_and_code(const char* description, BoolObjectClosure* is_alive, GCTimer* timer) {
2519 GCTraceTime(Debug, gc, phases) debug(description, timer);
2520
2521 ClassUnloadingContext ctx(workers()->active_workers(),
2522 false /* unregister_nmethods_during_purge */,
2523 false /* lock_codeblob_free_separately */);
2524 {
2525 CodeCache::UnlinkingScope scope(is_alive);
2526 bool unloading_occurred = SystemDictionary::do_unloading(timer);
2527 GCTraceTime(Debug, gc, phases) t("G1 Complete Cleaning", timer);
2528 complete_cleaning(unloading_occurred);
2529 }
2530 {
2531 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", timer);
2532 ctx.purge_nmethods();
2533 }
2534 {
2535 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", timer);
2536 G1CollectedHeap::heap()->bulk_unregister_nmethods();
2537 }
2538 {
2539 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", timer);
2540 ctx.free_code_blobs();
2541 }
2542 {
2543 GCTraceTime(Debug, gc, phases) t("Purge Class Loader Data", timer);
2544 ClassLoaderDataGraph::purge(true /* at_safepoint */);
2545 DEBUG_ONLY(MetaspaceUtils::verify();)
2546 }
2547 }
2548
2549 class G1BulkUnregisterNMethodTask : public WorkerTask {
2550 HeapRegionClaimer _hrclaimer;
2551
2552 class UnregisterNMethodsHeapRegionClosure : public HeapRegionClosure {
2553 public:
2554
2555 bool do_heap_region(HeapRegion* hr) {
2556 hr->rem_set()->bulk_remove_code_roots();
2557 return false;
2558 }
2559 } _cl;
2560
2561 public:
2562 G1BulkUnregisterNMethodTask(uint num_workers)
2563 : WorkerTask("G1 Remove Unlinked NMethods From Code Root Set Task"),
2564 _hrclaimer(num_workers) { }
2565
2566 void work(uint worker_id) {
2567 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&_cl, &_hrclaimer, worker_id);
2568 }
2569 };
2570
2571 void G1CollectedHeap::bulk_unregister_nmethods() {
2572 uint num_workers = workers()->active_workers();
2573 G1BulkUnregisterNMethodTask t(num_workers);
2574 workers()->run_task(&t);
2575 }
2576
2577 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2578 assert(obj != nullptr, "must not be null");
2579 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2580 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2581 // may falsely indicate that this is not the case here: however the collection set only
2582 // contains old regions when concurrent mark is not running.
2583 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2584 }
2585
2586 void G1CollectedHeap::make_pending_list_reachable() {
2587 if (collector_state()->in_concurrent_start_gc()) {
2588 oop pll_head = Universe::reference_pending_list();
2589 if (pll_head != nullptr) {
2590 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2591 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2592 }
2593 }
2594 }
2595
2596 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2597 _num_humongous_objects = num_humongous_total;
2598 _num_humongous_reclaim_candidates = num_humongous_candidates;
2599 }
2600
2601 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2602 const G1CollectionSetCandidates* candidates = collection_set()->candidates();
2603 return !candidates->is_empty();
2604 }
2605
2606 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2607 _collection_set_candidates_card_set_stats = stats;
2608 }
2609
2610 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2611 _young_gen_card_set_stats = stats;
2612 }
2613
2614 void G1CollectedHeap::record_obj_copy_mem_stats() {
2615 policy()->old_gen_alloc_tracker()->
2616 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2617
2618 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2619 create_g1_evac_summary(&_old_evac_stats));
2620 }
2621
2622 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2623 concurrent_mark()->clear_bitmap_for_region(hr);
2624 }
2625
2626 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2627 assert(!hr->is_free(), "the region should not be free");
2628 assert(!hr->is_empty(), "the region should not be empty");
2629 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2630 assert(!hr->has_pinned_objects(),
2631 "must not free a region which contains pinned objects");
2632
2633 // Reset region metadata to allow reuse.
2634 hr->hr_clear(true /* clear_space */);
2635 _policy->remset_tracker()->update_at_free(hr);
2636
2637 if (free_list != nullptr) {
2638 free_list->add_ordered(hr);
2639 }
2640 }
2641
2642 void G1CollectedHeap::retain_region(HeapRegion* hr) {
2643 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
2644 collection_set()->candidates()->add_retained_region_unsorted(hr);
2645 }
2646
2647 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2648 FreeRegionList* free_list) {
2649 assert(hr->is_humongous(), "this is only for humongous regions");
2650 hr->clear_humongous();
2651 free_region(hr, free_list);
2652 }
2653
2654 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2655 const uint humongous_regions_removed) {
2656 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
2657 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2658 _old_set.bulk_remove(old_regions_removed);
2659 _humongous_set.bulk_remove(humongous_regions_removed);
2660 }
2661
2662 }
2663
2664 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2665 assert(list != nullptr, "list can't be null");
2666 if (!list->is_empty()) {
2667 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2668 _hrm.insert_list_into_free_list(list);
2669 }
2670 }
2671
2672 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2673 decrease_used(bytes);
2674 }
2675
2676 void G1CollectedHeap::clear_eden() {
2677 _eden.clear();
2678 }
2679
2680 void G1CollectedHeap::clear_collection_set() {
2681 collection_set()->clear();
2682 }
2683
2684 void G1CollectedHeap::rebuild_free_region_list() {
2685 Ticks start = Ticks::now();
2686 _hrm.rebuild_free_list(workers());
2687 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2688 }
2689
2690 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2691 public:
2692 virtual bool do_heap_region(HeapRegion* r) {
2693 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2694 G1CollectedHeap::heap()->clear_region_attr(r);
2695 r->clear_young_index_in_cset();
2696 return false;
2697 }
2698 };
2699
2700 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2701 G1AbandonCollectionSetClosure cl;
2702 collection_set_iterate_all(&cl);
2703
2704 collection_set->clear();
2705 collection_set->stop_incremental_building();
2706 }
2707
2708 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2709 return _allocator->is_retained_old_region(hr);
2710 }
2711
2712 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2713 _eden.add(hr);
2714 _policy->set_region_eden(hr);
2715 }
2716
2717 #ifdef ASSERT
2718
2719 class NoYoungRegionsClosure: public HeapRegionClosure {
2720 private:
2721 bool _success;
2722 public:
2723 NoYoungRegionsClosure() : _success(true) { }
2724 bool do_heap_region(HeapRegion* r) {
2725 if (r->is_young()) {
2726 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2727 p2i(r->bottom()), p2i(r->end()));
2728 _success = false;
2729 }
2730 return false;
2731 }
2732 bool success() { return _success; }
2733 };
2734
2735 bool G1CollectedHeap::check_young_list_empty() {
2736 bool ret = (young_regions_count() == 0);
2737
2738 NoYoungRegionsClosure closure;
2739 heap_region_iterate(&closure);
2740 ret = ret && closure.success();
2741
2742 return ret;
2743 }
2744
2745 #endif // ASSERT
2746
2747 // Remove the given HeapRegion from the appropriate region set.
2748 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2749 if (hr->is_humongous()) {
2750 _humongous_set.remove(hr);
2751 } else if (hr->is_old()) {
2752 _old_set.remove(hr);
2753 } else if (hr->is_young()) {
2754 // Note that emptying the eden and survivor lists is postponed and instead
2755 // done as the first step when rebuilding the regions sets again. The reason
2756 // for this is that during a full GC string deduplication needs to know if
2757 // a collected region was young or old when the full GC was initiated.
2758 hr->uninstall_surv_rate_group();
2759 } else {
2760 // We ignore free regions, we'll empty the free list afterwards.
2761 assert(hr->is_free(), "it cannot be another type");
2762 }
2763 }
2764
2765 void G1CollectedHeap::increase_used(size_t bytes) {
2766 _summary_bytes_used += bytes;
2767 }
2768
2769 void G1CollectedHeap::decrease_used(size_t bytes) {
2770 assert(_summary_bytes_used >= bytes,
2771 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2772 _summary_bytes_used, bytes);
2773 _summary_bytes_used -= bytes;
2774 }
2775
2776 void G1CollectedHeap::set_used(size_t bytes) {
2777 _summary_bytes_used = bytes;
2778 }
2779
2780 class RebuildRegionSetsClosure : public HeapRegionClosure {
2781 private:
2782 bool _free_list_only;
2783
2784 HeapRegionSet* _old_set;
2785 HeapRegionSet* _humongous_set;
2786
2787 HeapRegionManager* _hrm;
2788
2789 size_t _total_used;
2790
2791 public:
2792 RebuildRegionSetsClosure(bool free_list_only,
2793 HeapRegionSet* old_set,
2794 HeapRegionSet* humongous_set,
2795 HeapRegionManager* hrm) :
2796 _free_list_only(free_list_only), _old_set(old_set),
2797 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2798 assert(_hrm->num_free_regions() == 0, "pre-condition");
2799 if (!free_list_only) {
2800 assert(_old_set->is_empty(), "pre-condition");
2801 assert(_humongous_set->is_empty(), "pre-condition");
2802 }
2803 }
2804
2805 bool do_heap_region(HeapRegion* r) {
2806 if (r->is_empty()) {
2807 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2808 // Add free regions to the free list
2809 r->set_free();
2810 _hrm->insert_into_free_list(r);
2811 } else if (!_free_list_only) {
2812 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2813
2814 if (r->is_humongous()) {
2815 _humongous_set->add(r);
2816 } else {
2817 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2818 // We now move all (non-humongous, non-old) regions to old gen,
2819 // and register them as such.
2820 r->move_to_old();
2821 _old_set->add(r);
2822 }
2823 _total_used += r->used();
2824 }
2825
2826 return false;
2827 }
2828
2829 size_t total_used() {
2830 return _total_used;
2831 }
2832 };
2833
2834 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2835 assert_at_safepoint_on_vm_thread();
2836
2837 if (!free_list_only) {
2838 _eden.clear();
2839 _survivor.clear();
2840 }
2841
2842 RebuildRegionSetsClosure cl(free_list_only,
2843 &_old_set, &_humongous_set,
2844 &_hrm);
2845 heap_region_iterate(&cl);
2846
2847 if (!free_list_only) {
2848 set_used(cl.total_used());
2849 }
2850 assert_used_and_recalculate_used_equal(this);
2851 }
2852
2853 // Methods for the mutator alloc region
2854
2855 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2856 bool force,
2857 uint node_index) {
2858 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2859 bool should_allocate = policy()->should_allocate_mutator_region();
2860 if (force || should_allocate) {
2861 HeapRegion* new_alloc_region = new_region(word_size,
2862 HeapRegionType::Eden,
2863 false /* do_expand */,
2864 node_index);
2865 if (new_alloc_region != nullptr) {
2866 set_region_short_lived_locked(new_alloc_region);
2867 _hr_printer.alloc(new_alloc_region, !should_allocate);
2868 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2869 return new_alloc_region;
2870 }
2871 }
2872 return nullptr;
2873 }
2874
2875 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
2876 size_t allocated_bytes) {
2877 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2878 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
2879
2880 collection_set()->add_eden_region(alloc_region);
2881 increase_used(allocated_bytes);
2882 _eden.add_used_bytes(allocated_bytes);
2883 _hr_printer.retire(alloc_region);
2884
2885 // We update the eden sizes here, when the region is retired,
2886 // instead of when it's allocated, since this is the point that its
2887 // used space has been recorded in _summary_bytes_used.
2888 monitoring_support()->update_eden_size();
2889 }
2890
2891 // Methods for the GC alloc regions
2892
2893 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
2894 if (dest.is_old()) {
2895 return true;
2896 } else {
2897 return survivor_regions_count() < policy()->max_survivor_regions();
2898 }
2899 }
2900
2901 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
2902 assert(FreeList_lock->owned_by_self(), "pre-condition");
2903
2904 if (!has_more_regions(dest)) {
2905 return nullptr;
2906 }
2907
2908 HeapRegionType type;
2909 if (dest.is_young()) {
2910 type = HeapRegionType::Survivor;
2911 } else {
2912 type = HeapRegionType::Old;
2913 }
2914
2915 HeapRegion* new_alloc_region = new_region(word_size,
2916 type,
2917 true /* do_expand */,
2918 node_index);
2919
2920 if (new_alloc_region != nullptr) {
2921 if (type.is_survivor()) {
2922 new_alloc_region->set_survivor();
2923 _survivor.add(new_alloc_region);
2924 register_new_survivor_region_with_region_attr(new_alloc_region);
2925 } else {
2926 new_alloc_region->set_old();
2927 }
2928 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2929 register_region_with_region_attr(new_alloc_region);
2930 _hr_printer.alloc(new_alloc_region);
2931 return new_alloc_region;
2932 }
2933 return nullptr;
2934 }
2935
2936 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
2937 size_t allocated_bytes,
2938 G1HeapRegionAttr dest) {
2939 _bytes_used_during_gc += allocated_bytes;
2940 if (dest.is_old()) {
2941 old_set_add(alloc_region);
2942 } else {
2943 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
2944 _survivor.add_used_bytes(allocated_bytes);
2945 }
2946
2947 bool const during_im = collector_state()->in_concurrent_start_gc();
2948 if (during_im && allocated_bytes > 0) {
2949 _cm->add_root_region(alloc_region);
2950 }
2951 _hr_printer.retire(alloc_region);
2952 }
2953
2954 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
2955 bool expanded = false;
2956 uint index = _hrm.find_highest_free(&expanded);
2957
2958 if (index != G1_NO_HRM_INDEX) {
2959 if (expanded) {
2960 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
2961 HeapRegion::GrainWords * HeapWordSize);
2962 }
2963 return _hrm.allocate_free_regions_starting_at(index, 1);
2964 }
2965 return nullptr;
2966 }
2967
2968 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
2969 assert(!_cm->is_marked_in_bitmap(obj), "must be");
2970
2971 _cm->raw_mark_in_bitmap(obj);
2972 }
2973
2974 // Optimized nmethod scanning
2975 class RegisterNMethodOopClosure: public OopClosure {
2976 G1CollectedHeap* _g1h;
2977 nmethod* _nm;
2978
2979 public:
2980 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
2981 _g1h(g1h), _nm(nm) {}
2982
2983 void do_oop(oop* p) {
2984 oop heap_oop = RawAccess<>::oop_load(p);
2985 if (!CompressedOops::is_null(heap_oop)) {
2986 oop obj = CompressedOops::decode_not_null(heap_oop);
2987 HeapRegion* hr = _g1h->heap_region_containing(obj);
2988 assert(!hr->is_continues_humongous(),
2989 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
2990 " starting at " HR_FORMAT,
2991 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
2992
2993 hr->add_code_root(_nm);
2994 }
2995 }
2996
2997 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2998 };
2999
3000 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3001 guarantee(nm != nullptr, "sanity");
3002 RegisterNMethodOopClosure reg_cl(this, nm);
3003 nm->oops_do(®_cl);
3004 }
3005
3006 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3007 // We always unregister nmethods in bulk during code unloading only.
3008 ShouldNotReachHere();
3009 }
3010
3011 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3012 if (evacuation_failed) {
3013 set_used(recalculate_used());
3014 } else {
3015 // The "used" of the collection set have already been subtracted
3016 // when they were freed. Add in the bytes used.
3017 increase_used(_bytes_used_during_gc);
3018 }
3019 }
3020
3021 class RebuildCodeRootClosure: public CodeBlobClosure {
3022 G1CollectedHeap* _g1h;
3023
3024 public:
3025 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3026 _g1h(g1h) {}
3027
3028 void do_code_blob(CodeBlob* cb) {
3029 nmethod* nm = cb->as_nmethod_or_null();
3030 if (nm != nullptr) {
3031 _g1h->register_nmethod(nm);
3032 }
3033 }
3034 };
3035
3036 void G1CollectedHeap::rebuild_code_roots() {
3037 RebuildCodeRootClosure blob_cl(this);
3038 CodeCache::blobs_do(&blob_cl);
3039 }
3040
3041 void G1CollectedHeap::initialize_serviceability() {
3042 _monitoring_support->initialize_serviceability();
3043 }
3044
3045 MemoryUsage G1CollectedHeap::memory_usage() {
3046 return _monitoring_support->memory_usage();
3047 }
3048
3049 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3050 return _monitoring_support->memory_managers();
3051 }
3052
3053 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3054 return _monitoring_support->memory_pools();
3055 }
3056
3057 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3058 HeapRegion* region = heap_region_containing(start);
3059 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3060 }
3061
3062 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3063 // We can reach here with an active code cache marking cycle either because the
3064 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3065 // concurrent start young collection was below the threshold) or aborted. See
3066 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3067 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3068 // still have to arm all nmethod entry barriers. They are needed for adding oop
3069 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3070 if (!CodeCache::is_gc_marking_cycle_active()) {
3071 CodeCache::on_gc_marking_cycle_start();
3072 }
3073 if (concurrent_mark_start) {
3074 CodeCache::arm_all_nmethods();
3075 }
3076 }
3077
3078 void G1CollectedHeap::finish_codecache_marking_cycle() {
3079 CodeCache::on_gc_marking_cycle_finish();
3080 CodeCache::arm_all_nmethods();
3081 }