1 /*
2 * Copyright (c) 2001, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "compiler/oopMap.hpp"
32 #include "gc/g1/g1Allocator.inline.hpp"
33 #include "gc/g1/g1Arguments.hpp"
34 #include "gc/g1/g1BarrierSet.hpp"
35 #include "gc/g1/g1BatchedTask.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectionSetCandidates.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1ConcurrentRefine.hpp"
41 #include "gc/g1/g1ConcurrentRefineThread.hpp"
42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
43 #include "gc/g1/g1DirtyCardQueue.hpp"
44 #include "gc/g1/g1EvacStats.inline.hpp"
45 #include "gc/g1/g1FullCollector.hpp"
46 #include "gc/g1/g1GCCounters.hpp"
47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
48 #include "gc/g1/g1GCPhaseTimes.hpp"
49 #include "gc/g1/g1GCPauseType.hpp"
50 #include "gc/g1/g1HeapSizingPolicy.hpp"
51 #include "gc/g1/g1HeapTransition.hpp"
52 #include "gc/g1/g1HeapVerifier.hpp"
53 #include "gc/g1/g1InitLogger.hpp"
54 #include "gc/g1/g1MemoryPool.hpp"
55 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp"
56 #include "gc/g1/g1OopClosures.inline.hpp"
57 #include "gc/g1/g1ParallelCleaning.hpp"
58 #include "gc/g1/g1ParScanThreadState.inline.hpp"
59 #include "gc/g1/g1PeriodicGCTask.hpp"
60 #include "gc/g1/g1Policy.hpp"
61 #include "gc/g1/g1RedirtyCardsQueue.hpp"
62 #include "gc/g1/g1RegionToSpaceMapper.hpp"
63 #include "gc/g1/g1RemSet.hpp"
64 #include "gc/g1/g1RootClosures.hpp"
65 #include "gc/g1/g1RootProcessor.hpp"
66 #include "gc/g1/g1SATBMarkQueueSet.hpp"
67 #include "gc/g1/g1ServiceThread.hpp"
68 #include "gc/g1/g1ThreadLocalData.hpp"
69 #include "gc/g1/g1Trace.hpp"
70 #include "gc/g1/g1UncommitRegionTask.hpp"
71 #include "gc/g1/g1VMOperations.hpp"
72 #include "gc/g1/g1YoungCollector.hpp"
73 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp"
74 #include "gc/g1/heapRegion.inline.hpp"
75 #include "gc/g1/heapRegionRemSet.inline.hpp"
76 #include "gc/g1/heapRegionSet.inline.hpp"
77 #include "gc/shared/concurrentGCBreakpoints.hpp"
78 #include "gc/shared/gcBehaviours.hpp"
79 #include "gc/shared/gcForwarding.hpp"
80 #include "gc/shared/gcHeapSummary.hpp"
81 #include "gc/shared/gcId.hpp"
82 #include "gc/shared/gcLocker.inline.hpp"
83 #include "gc/shared/gcTimer.hpp"
84 #include "gc/shared/gcTraceTime.inline.hpp"
85 #include "gc/shared/generationSpec.hpp"
86 #include "gc/shared/isGCActiveMark.hpp"
87 #include "gc/shared/locationPrinter.inline.hpp"
88 #include "gc/shared/oopStorageParState.hpp"
89 #include "gc/shared/preservedMarks.inline.hpp"
90 #include "gc/shared/referenceProcessor.inline.hpp"
91 #include "gc/shared/suspendibleThreadSet.hpp"
92 #include "gc/shared/taskqueue.inline.hpp"
93 #include "gc/shared/taskTerminator.hpp"
94 #include "gc/shared/tlab_globals.hpp"
95 #include "gc/shared/workerPolicy.hpp"
96 #include "gc/shared/weakProcessor.inline.hpp"
97 #include "logging/log.hpp"
98 #include "memory/allocation.hpp"
99 #include "memory/heapInspection.hpp"
100 #include "memory/iterator.hpp"
101 #include "memory/metaspaceUtils.hpp"
102 #include "memory/resourceArea.hpp"
103 #include "memory/universe.hpp"
104 #include "oops/access.inline.hpp"
105 #include "oops/compressedOops.inline.hpp"
106 #include "oops/oop.inline.hpp"
107 #include "runtime/atomic.hpp"
108 #include "runtime/handles.inline.hpp"
109 #include "runtime/init.hpp"
110 #include "runtime/java.hpp"
111 #include "runtime/orderAccess.hpp"
112 #include "runtime/threadSMR.hpp"
113 #include "runtime/vmThread.hpp"
114 #include "utilities/align.hpp"
115 #include "utilities/autoRestore.hpp"
116 #include "utilities/bitMap.inline.hpp"
117 #include "utilities/globalDefinitions.hpp"
118 #include "utilities/stack.inline.hpp"
119
120 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
121
122 // INVARIANTS/NOTES
123 //
124 // All allocation activity covered by the G1CollectedHeap interface is
125 // serialized by acquiring the HeapLock. This happens in mem_allocate
126 // and allocate_new_tlab, which are the "entry" points to the
127 // allocation code from the rest of the JVM. (Note that this does not
128 // apply to TLAB allocation, which is not part of this interface: it
129 // is done by clients of this interface.)
130
131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
132 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
133 }
134
135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
136 // The from card cache is not the memory that is actually committed. So we cannot
137 // take advantage of the zero_filled parameter.
138 reset_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
142 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
143 cl->set_max_workers(num_workers);
144 workers()->run_task(cl, num_workers);
145 }
146
147 uint G1CollectedHeap::get_chunks_per_region() {
148 uint log_region_size = HeapRegion::LogOfHRGrainBytes;
149 // Limit the expected input values to current known possible values of the
150 // (log) region size. Adjust as necessary after testing if changing the permissible
151 // values for region size.
152 assert(log_region_size >= 20 && log_region_size <= 29,
153 "expected value in [20,29], but got %u", log_region_size);
154 return 1u << (log_region_size / 2 - 4);
155 }
156
157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
158 MemRegion mr) {
159 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
160 }
161
162 // Private methods.
163
164 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
165 HeapRegionType type,
166 bool do_expand,
167 uint node_index) {
168 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
169 "the only time we use this to allocate a humongous region is "
170 "when we are allocating a single humongous region");
171
172 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
173
174 if (res == nullptr && do_expand) {
175 // Currently, only attempts to allocate GC alloc regions set
176 // do_expand to true. So, we should only reach here during a
177 // safepoint.
178 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
179
180 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
181 word_size * HeapWordSize);
182
183 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
184 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
185 word_size * HeapWordSize);
186 if (expand_single_region(node_index)) {
187 // Given that expand_single_region() succeeded in expanding the heap, and we
188 // always expand the heap by an amount aligned to the heap
189 // region size, the free list should in theory not be empty.
190 // In either case allocate_free_region() will check for null.
191 res = _hrm.allocate_free_region(type, node_index);
192 }
193 }
194 return res;
195 }
196
197 void G1CollectedHeap::set_humongous_metadata(HeapRegion* first_hr,
198 uint num_regions,
199 size_t word_size,
200 bool update_remsets) {
201 // Calculate the new top of the humongous object.
202 HeapWord* obj_top = first_hr->bottom() + word_size;
203 // The word size sum of all the regions used
204 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
205 assert(word_size <= word_size_sum, "sanity");
206
207 // How many words memory we "waste" which cannot hold a filler object.
208 size_t words_not_fillable = 0;
209
210 // Pad out the unused tail of the last region with filler
211 // objects, for improved usage accounting.
212
213 // How many words can we use for filler objects.
214 size_t words_fillable = word_size_sum - word_size;
215
216 if (words_fillable >= G1CollectedHeap::min_fill_size()) {
217 G1CollectedHeap::fill_with_objects(obj_top, words_fillable);
218 } else {
219 // We have space to fill, but we cannot fit an object there.
220 words_not_fillable = words_fillable;
221 words_fillable = 0;
222 }
223
224 // We will set up the first region as "starts humongous". This
225 // will also update the BOT covering all the regions to reflect
226 // that there is a single object that starts at the bottom of the
227 // first region.
228 first_hr->hr_clear(false /* clear_space */);
229 first_hr->set_starts_humongous(obj_top, words_fillable);
230
231 if (update_remsets) {
232 _policy->remset_tracker()->update_at_allocate(first_hr);
233 }
234
235 // Indices of first and last regions in the series.
236 uint first = first_hr->hrm_index();
237 uint last = first + num_regions - 1;
238
239 HeapRegion* hr = nullptr;
240 for (uint i = first + 1; i <= last; ++i) {
241 hr = region_at(i);
242 hr->hr_clear(false /* clear_space */);
243 hr->set_continues_humongous(first_hr);
244 if (update_remsets) {
245 _policy->remset_tracker()->update_at_allocate(hr);
246 }
247 }
248
249 // Up to this point no concurrent thread would have been able to
250 // do any scanning on any region in this series. All the top
251 // fields still point to bottom, so the intersection between
252 // [bottom,top] and [card_start,card_end] will be empty. Before we
253 // update the top fields, we'll do a storestore to make sure that
254 // no thread sees the update to top before the zeroing of the
255 // object header and the BOT initialization.
256 OrderAccess::storestore();
257
258 // Now, we will update the top fields of the "continues humongous"
259 // regions except the last one.
260 for (uint i = first; i < last; ++i) {
261 hr = region_at(i);
262 hr->set_top(hr->end());
263 }
264
265 hr = region_at(last);
266 // If we cannot fit a filler object, we must set top to the end
267 // of the humongous object, otherwise we cannot iterate the heap
268 // and the BOT will not be complete.
269 hr->set_top(hr->end() - words_not_fillable);
270
271 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
272 "obj_top should be in last region");
273
274 assert(words_not_fillable == 0 ||
275 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
276 "Miscalculation in humongous allocation");
277 }
278
279 HeapWord*
280 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
281 uint num_regions,
282 size_t word_size) {
283 assert(first_hr != nullptr, "pre-condition");
284 assert(is_humongous(word_size), "word_size should be humongous");
285 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
286
287 // Index of last region in the series.
288 uint first = first_hr->hrm_index();
289 uint last = first + num_regions - 1;
290
291 // We need to initialize the region(s) we just discovered. This is
292 // a bit tricky given that it can happen concurrently with
293 // refinement threads refining cards on these regions and
294 // potentially wanting to refine the BOT as they are scanning
295 // those cards (this can happen shortly after a cleanup; see CR
296 // 6991377). So we have to set up the region(s) carefully and in
297 // a specific order.
298
299 // The passed in hr will be the "starts humongous" region. The header
300 // of the new object will be placed at the bottom of this region.
301 HeapWord* new_obj = first_hr->bottom();
302
303 // First, we need to zero the header of the space that we will be
304 // allocating. When we update top further down, some refinement
305 // threads might try to scan the region. By zeroing the header we
306 // ensure that any thread that will try to scan the region will
307 // come across the zero klass word and bail out.
308 //
309 // NOTE: It would not have been correct to have used
310 // CollectedHeap::fill_with_object() and make the space look like
311 // an int array. The thread that is doing the allocation will
312 // later update the object header to a potentially different array
313 // type and, for a very short period of time, the klass and length
314 // fields will be inconsistent. This could cause a refinement
315 // thread to calculate the object size incorrectly.
316 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
317
318 // Next, update the metadata for the regions.
319 set_humongous_metadata(first_hr, num_regions, word_size, true);
320
321 HeapRegion* last_hr = region_at(last);
322 size_t used = byte_size(first_hr->bottom(), last_hr->top());
323
324 increase_used(used);
325
326 for (uint i = first; i <= last; ++i) {
327 HeapRegion *hr = region_at(i);
328 _humongous_set.add(hr);
329 _hr_printer.alloc(hr);
330 }
331
332 return new_obj;
333 }
334
335 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
336 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
337 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
338 }
339
340 // If could fit into free regions w/o expansion, try.
341 // Otherwise, if can expand, do so.
342 // Otherwise, if using ex regions might help, try with ex given back.
343 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
344 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
345
346 _verifier->verify_region_sets_optional();
347
348 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
349
350 // Policy: First try to allocate a humongous object in the free list.
351 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
352 if (humongous_start == nullptr) {
353 // Policy: We could not find enough regions for the humongous object in the
354 // free list. Look through the heap to find a mix of free and uncommitted regions.
355 // If so, expand the heap and allocate the humongous object.
356 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
357 if (humongous_start != nullptr) {
358 // We managed to find a region by expanding the heap.
359 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
360 word_size * HeapWordSize);
361 policy()->record_new_heap_size(num_regions());
362 } else {
363 // Policy: Potentially trigger a defragmentation GC.
364 }
365 }
366
367 HeapWord* result = nullptr;
368 if (humongous_start != nullptr) {
369 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
370 assert(result != nullptr, "it should always return a valid result");
371
372 // A successful humongous object allocation changes the used space
373 // information of the old generation so we need to recalculate the
374 // sizes and update the jstat counters here.
375 monitoring_support()->update_sizes();
376 }
377
378 _verifier->verify_region_sets_optional();
379
380 return result;
381 }
382
383 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
384 size_t requested_size,
385 size_t* actual_size) {
386 assert_heap_not_locked_and_not_at_safepoint();
387 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
388
389 return attempt_allocation(min_size, requested_size, actual_size);
390 }
391
392 HeapWord*
393 G1CollectedHeap::mem_allocate(size_t word_size,
394 bool* gc_overhead_limit_was_exceeded) {
395 assert_heap_not_locked_and_not_at_safepoint();
396
397 if (is_humongous(word_size)) {
398 return attempt_allocation_humongous(word_size);
399 }
400 size_t dummy = 0;
401 return attempt_allocation(word_size, word_size, &dummy);
402 }
403
404 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
405 ResourceMark rm; // For retrieving the thread names in log messages.
406
407 // Make sure you read the note in attempt_allocation_humongous().
408
409 assert_heap_not_locked_and_not_at_safepoint();
410 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
411 "be called for humongous allocation requests");
412
413 // We should only get here after the first-level allocation attempt
414 // (attempt_allocation()) failed to allocate.
415
416 // We will loop until a) we manage to successfully perform the
417 // allocation or b) we successfully schedule a collection which
418 // fails to perform the allocation. b) is the only case when we'll
419 // return null.
420 HeapWord* result = nullptr;
421 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
422 bool should_try_gc;
423 uint gc_count_before;
424
425 {
426 MutexLocker x(Heap_lock);
427
428 // Now that we have the lock, we first retry the allocation in case another
429 // thread changed the region while we were waiting to acquire the lock.
430 result = _allocator->attempt_allocation_locked(word_size);
431 if (result != nullptr) {
432 return result;
433 }
434
435 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
436 // This is different to when only GCLocker::needs_gc() is set: try to avoid
437 // waiting because the GCLocker is active to not wait too long.
438 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
439 // No need for an ergo message here, can_expand_young_list() does this when
440 // it returns true.
441 result = _allocator->attempt_allocation_force(word_size);
442 if (result != nullptr) {
443 return result;
444 }
445 }
446
447 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
448 // the GCLocker initiated GC has been performed and then retry. This includes
449 // the case when the GC Locker is not active but has not been performed.
450 should_try_gc = !GCLocker::needs_gc();
451 // Read the GC count while still holding the Heap_lock.
452 gc_count_before = total_collections();
453 }
454
455 if (should_try_gc) {
456 bool succeeded;
457 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
458 if (result != nullptr) {
459 assert(succeeded, "only way to get back a non-null result");
460 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
461 Thread::current()->name(), p2i(result));
462 return result;
463 }
464
465 if (succeeded) {
466 // We successfully scheduled a collection which failed to allocate. No
467 // point in trying to allocate further. We'll just return null.
468 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
469 SIZE_FORMAT " words", Thread::current()->name(), word_size);
470 return nullptr;
471 }
472 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
473 Thread::current()->name(), word_size);
474 } else {
475 // Failed to schedule a collection.
476 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
477 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
478 SIZE_FORMAT " words", Thread::current()->name(), word_size);
479 return nullptr;
480 }
481 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
482 // The GCLocker is either active or the GCLocker initiated
483 // GC has not yet been performed. Stall until it is and
484 // then retry the allocation.
485 GCLocker::stall_until_clear();
486 gclocker_retry_count += 1;
487 }
488
489 // We can reach here if we were unsuccessful in scheduling a
490 // collection (because another thread beat us to it) or if we were
491 // stalled due to the GC locker. In either can we should retry the
492 // allocation attempt in case another thread successfully
493 // performed a collection and reclaimed enough space. We do the
494 // first attempt (without holding the Heap_lock) here and the
495 // follow-on attempt will be at the start of the next loop
496 // iteration (after taking the Heap_lock).
497 size_t dummy = 0;
498 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
499 if (result != nullptr) {
500 return result;
501 }
502
503 // Give a warning if we seem to be looping forever.
504 if ((QueuedAllocationWarningCount > 0) &&
505 (try_count % QueuedAllocationWarningCount == 0)) {
506 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
507 Thread::current()->name(), try_count, word_size);
508 }
509 }
510
511 ShouldNotReachHere();
512 return nullptr;
513 }
514
515 template <typename Func>
516 void G1CollectedHeap::iterate_regions_in_range(MemRegion range, const Func& func) {
517 // Mark each G1 region touched by the range as old, add it to
518 // the old set, and set top.
519 HeapRegion* curr_region = _hrm.addr_to_region(range.start());
520 HeapRegion* end_region = _hrm.addr_to_region(range.last());
521
522 while (curr_region != nullptr) {
523 bool is_last = curr_region == end_region;
524 HeapRegion* next_region = is_last ? nullptr : _hrm.next_region_in_heap(curr_region);
525
526 func(curr_region, is_last);
527
528 curr_region = next_region;
529 }
530 }
531
532 HeapWord* G1CollectedHeap::alloc_archive_region(size_t word_size, HeapWord* preferred_addr) {
533 assert(!is_init_completed(), "Expect to be called at JVM init time");
534 MutexLocker x(Heap_lock);
535
536 MemRegion reserved = _hrm.reserved();
537
538 if (reserved.word_size() <= word_size) {
539 log_info(gc, heap)("Unable to allocate regions as archive heap is too large; size requested = " SIZE_FORMAT
540 " bytes, heap = " SIZE_FORMAT " bytes", word_size, reserved.word_size());
541 return nullptr;
542 }
543
544 // Temporarily disable pretouching of heap pages. This interface is used
545 // when mmap'ing archived heap data in, so pre-touching is wasted.
546 FlagSetting fs(AlwaysPreTouch, false);
547
548 size_t commits = 0;
549 // Attempt to allocate towards the end of the heap.
550 HeapWord* start_addr = reserved.end() - align_up(word_size, HeapRegion::GrainWords);
551 MemRegion range = MemRegion(start_addr, word_size);
552 HeapWord* last_address = range.last();
553 if (!_hrm.allocate_containing_regions(range, &commits, workers())) {
554 return nullptr;
555 }
556 increase_used(word_size * HeapWordSize);
557 if (commits != 0) {
558 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
559 HeapRegion::GrainWords * HeapWordSize * commits);
560 }
561
562 // Mark each G1 region touched by the range as old, add it to
563 // the old set, and set top.
564 auto set_region_to_old = [&] (HeapRegion* r, bool is_last) {
565 assert(r->is_empty(), "Region already in use (%u)", r->hrm_index());
566
567 HeapWord* top = is_last ? last_address + 1 : r->end();
568 r->set_top(top);
569
570 r->set_old();
571 _hr_printer.alloc(r);
572 _old_set.add(r);
573 };
574
575 iterate_regions_in_range(range, set_region_to_old);
576 return start_addr;
577 }
578
579 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion range) {
580 assert(!is_init_completed(), "Expect to be called at JVM init time");
581
582 iterate_regions_in_range(range,
583 [&] (HeapRegion* r, bool is_last) {
584 r->update_bot();
585 });
586 }
587
588 void G1CollectedHeap::dealloc_archive_regions(MemRegion range) {
589 assert(!is_init_completed(), "Expect to be called at JVM init time");
590 MemRegion reserved = _hrm.reserved();
591 size_t size_used = 0;
592 uint shrink_count = 0;
593
594 // Free the G1 regions that are within the specified range.
595 MutexLocker x(Heap_lock);
596 HeapWord* start_address = range.start();
597 HeapWord* last_address = range.last();
598
599 assert(reserved.contains(start_address) && reserved.contains(last_address),
600 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
601 p2i(start_address), p2i(last_address));
602 size_used += range.byte_size();
603
604 // Free, empty and uncommit regions with CDS archive content.
605 auto dealloc_archive_region = [&] (HeapRegion* r, bool is_last) {
606 guarantee(r->is_old(), "Expected old region at index %u", r->hrm_index());
607 _old_set.remove(r);
608 r->set_free();
609 r->set_top(r->bottom());
610 _hrm.shrink_at(r->hrm_index(), 1);
611 shrink_count++;
612 };
613
614 iterate_regions_in_range(range, dealloc_archive_region);
615
616 if (shrink_count != 0) {
617 log_debug(gc, ergo, heap)("Attempt heap shrinking (CDS archive regions). Total size: " SIZE_FORMAT "B",
618 HeapRegion::GrainWords * HeapWordSize * shrink_count);
619 // Explicit uncommit.
620 uncommit_regions(shrink_count);
621 }
622 decrease_used(size_used);
623 }
624
625 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
626 size_t desired_word_size,
627 size_t* actual_word_size) {
628 assert_heap_not_locked_and_not_at_safepoint();
629 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
630 "be called for humongous allocation requests");
631
632 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
633
634 if (result == nullptr) {
635 *actual_word_size = desired_word_size;
636 result = attempt_allocation_slow(desired_word_size);
637 }
638
639 assert_heap_not_locked();
640 if (result != nullptr) {
641 assert(*actual_word_size != 0, "Actual size must have been set here");
642 dirty_young_block(result, *actual_word_size);
643 } else {
644 *actual_word_size = 0;
645 }
646
647 return result;
648 }
649
650 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
651 ResourceMark rm; // For retrieving the thread names in log messages.
652
653 // The structure of this method has a lot of similarities to
654 // attempt_allocation_slow(). The reason these two were not merged
655 // into a single one is that such a method would require several "if
656 // allocation is not humongous do this, otherwise do that"
657 // conditional paths which would obscure its flow. In fact, an early
658 // version of this code did use a unified method which was harder to
659 // follow and, as a result, it had subtle bugs that were hard to
660 // track down. So keeping these two methods separate allows each to
661 // be more readable. It will be good to keep these two in sync as
662 // much as possible.
663
664 assert_heap_not_locked_and_not_at_safepoint();
665 assert(is_humongous(word_size), "attempt_allocation_humongous() "
666 "should only be called for humongous allocations");
667
668 // Humongous objects can exhaust the heap quickly, so we should check if we
669 // need to start a marking cycle at each humongous object allocation. We do
670 // the check before we do the actual allocation. The reason for doing it
671 // before the allocation is that we avoid having to keep track of the newly
672 // allocated memory while we do a GC.
673 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
674 word_size)) {
675 collect(GCCause::_g1_humongous_allocation);
676 }
677
678 // We will loop until a) we manage to successfully perform the
679 // allocation or b) we successfully schedule a collection which
680 // fails to perform the allocation. b) is the only case when we'll
681 // return null.
682 HeapWord* result = nullptr;
683 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
684 bool should_try_gc;
685 uint gc_count_before;
686
687
688 {
689 MutexLocker x(Heap_lock);
690
691 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
692 // Given that humongous objects are not allocated in young
693 // regions, we'll first try to do the allocation without doing a
694 // collection hoping that there's enough space in the heap.
695 result = humongous_obj_allocate(word_size);
696 if (result != nullptr) {
697 policy()->old_gen_alloc_tracker()->
698 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
699 return result;
700 }
701
702 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
703 // the GCLocker initiated GC has been performed and then retry. This includes
704 // the case when the GC Locker is not active but has not been performed.
705 should_try_gc = !GCLocker::needs_gc();
706 // Read the GC count while still holding the Heap_lock.
707 gc_count_before = total_collections();
708 }
709
710 if (should_try_gc) {
711 bool succeeded;
712 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
713 if (result != nullptr) {
714 assert(succeeded, "only way to get back a non-null result");
715 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
716 Thread::current()->name(), p2i(result));
717 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
718 policy()->old_gen_alloc_tracker()->
719 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
720 return result;
721 }
722
723 if (succeeded) {
724 // We successfully scheduled a collection which failed to allocate. No
725 // point in trying to allocate further. We'll just return null.
726 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
727 SIZE_FORMAT " words", Thread::current()->name(), word_size);
728 return nullptr;
729 }
730 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
731 Thread::current()->name(), word_size);
732 } else {
733 // Failed to schedule a collection.
734 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
735 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
736 SIZE_FORMAT " words", Thread::current()->name(), word_size);
737 return nullptr;
738 }
739 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
740 // The GCLocker is either active or the GCLocker initiated
741 // GC has not yet been performed. Stall until it is and
742 // then retry the allocation.
743 GCLocker::stall_until_clear();
744 gclocker_retry_count += 1;
745 }
746
747
748 // We can reach here if we were unsuccessful in scheduling a
749 // collection (because another thread beat us to it) or if we were
750 // stalled due to the GC locker. In either can we should retry the
751 // allocation attempt in case another thread successfully
752 // performed a collection and reclaimed enough space.
753 // Humongous object allocation always needs a lock, so we wait for the retry
754 // in the next iteration of the loop, unlike for the regular iteration case.
755 // Give a warning if we seem to be looping forever.
756
757 if ((QueuedAllocationWarningCount > 0) &&
758 (try_count % QueuedAllocationWarningCount == 0)) {
759 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
760 Thread::current()->name(), try_count, word_size);
761 }
762 }
763
764 ShouldNotReachHere();
765 return nullptr;
766 }
767
768 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
769 bool expect_null_mutator_alloc_region) {
770 assert_at_safepoint_on_vm_thread();
771 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
772 "the current alloc region was unexpectedly found to be non-null");
773
774 if (!is_humongous(word_size)) {
775 return _allocator->attempt_allocation_locked(word_size);
776 } else {
777 HeapWord* result = humongous_obj_allocate(word_size);
778 if (result != nullptr && policy()->need_to_start_conc_mark("STW humongous allocation")) {
779 collector_state()->set_initiate_conc_mark_if_possible(true);
780 }
781 return result;
782 }
783
784 ShouldNotReachHere();
785 }
786
787 class PostCompactionPrinterClosure: public HeapRegionClosure {
788 private:
789 G1HRPrinter* _hr_printer;
790 public:
791 bool do_heap_region(HeapRegion* hr) {
792 assert(!hr->is_young(), "not expecting to find young regions");
793 _hr_printer->post_compaction(hr);
794 return false;
795 }
796
797 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
798 : _hr_printer(hr_printer) { }
799 };
800
801 void G1CollectedHeap::print_heap_after_full_collection() {
802 // Post collection region logging.
803 // We should do this after we potentially resize the heap so
804 // that all the COMMIT / UNCOMMIT events are generated before
805 // the compaction events.
806 if (_hr_printer.is_active()) {
807 PostCompactionPrinterClosure cl(hr_printer());
808 heap_region_iterate(&cl);
809 }
810 }
811
812 bool G1CollectedHeap::abort_concurrent_cycle() {
813 // Disable discovery and empty the discovered lists
814 // for the CM ref processor.
815 _ref_processor_cm->disable_discovery();
816 _ref_processor_cm->abandon_partial_discovery();
817 _ref_processor_cm->verify_no_references_recorded();
818
819 // Abandon current iterations of concurrent marking and concurrent
820 // refinement, if any are in progress.
821 return concurrent_mark()->concurrent_cycle_abort();
822 }
823
824 void G1CollectedHeap::prepare_heap_for_full_collection() {
825 // Make sure we'll choose a new allocation region afterwards.
826 _allocator->release_mutator_alloc_regions();
827 _allocator->abandon_gc_alloc_regions();
828
829 // We may have added regions to the current incremental collection
830 // set between the last GC or pause and now. We need to clear the
831 // incremental collection set and then start rebuilding it afresh
832 // after this full GC.
833 abandon_collection_set(collection_set());
834
835 _hrm.remove_all_free_regions();
836 }
837
838 void G1CollectedHeap::verify_before_full_collection() {
839 assert_used_and_recalculate_used_equal(this);
840 if (!VerifyBeforeGC) {
841 return;
842 }
843 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
844 return;
845 }
846 _verifier->verify_region_sets_optional();
847 _verifier->verify_before_gc();
848 _verifier->verify_bitmap_clear(true /* above_tams_only */);
849 }
850
851 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
852 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
853 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
854 DEBUG_ONLY(MetaspaceUtils::verify();)
855
856 // Prepare heap for normal collections.
857 assert(num_free_regions() == 0, "we should not have added any free regions");
858 rebuild_region_sets(false /* free_list_only */);
859 abort_refinement();
860 resize_heap_if_necessary();
861 uncommit_regions_if_necessary();
862
863 // Rebuild the code root lists for each region
864 rebuild_code_roots();
865
866 start_new_collection_set();
867 _allocator->init_mutator_alloc_regions();
868
869 // Post collection state updates.
870 MetaspaceGC::compute_new_size();
871 }
872
873 void G1CollectedHeap::abort_refinement() {
874 // Discard all remembered set updates and reset refinement statistics.
875 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
876 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
877 "DCQS should be empty");
878 concurrent_refine()->get_and_reset_refinement_stats();
879 }
880
881 void G1CollectedHeap::verify_after_full_collection() {
882 if (!VerifyAfterGC) {
883 return;
884 }
885 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
886 return;
887 }
888 _hrm.verify_optional();
889 _verifier->verify_region_sets_optional();
890 _verifier->verify_after_gc();
891 _verifier->verify_bitmap_clear(false /* above_tams_only */);
892
893 // At this point there should be no regions in the
894 // entire heap tagged as young.
895 assert(check_young_list_empty(), "young list should be empty at this point");
896
897 // Note: since we've just done a full GC, concurrent
898 // marking is no longer active. Therefore we need not
899 // re-enable reference discovery for the CM ref processor.
900 // That will be done at the start of the next marking cycle.
901 // We also know that the STW processor should no longer
902 // discover any new references.
903 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
904 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
905 _ref_processor_stw->verify_no_references_recorded();
906 _ref_processor_cm->verify_no_references_recorded();
907 }
908
909 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs,
910 bool do_maximal_compaction) {
911 assert_at_safepoint_on_vm_thread();
912
913 if (GCLocker::check_active_before_gc()) {
914 // Full GC was not completed.
915 return false;
916 }
917
918 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
919 soft_ref_policy()->should_clear_all_soft_refs();
920
921 G1FullGCMark gc_mark;
922 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true);
923 G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
924
925 collector.prepare_collection();
926 collector.collect();
927 collector.complete_collection();
928
929 // Full collection was successfully completed.
930 return true;
931 }
932
933 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
934 // Currently, there is no facility in the do_full_collection(bool) API to notify
935 // the caller that the collection did not succeed (e.g., because it was locked
936 // out by the GC locker). So, right now, we'll ignore the return value.
937
938 do_full_collection(clear_all_soft_refs,
939 false /* do_maximal_compaction */);
940 }
941
942 bool G1CollectedHeap::upgrade_to_full_collection() {
943 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
944 log_info(gc, ergo)("Attempting full compaction clearing soft references");
945 bool success = do_full_collection(true /* clear_all_soft_refs */,
946 false /* do_maximal_compaction */);
947 // do_full_collection only fails if blocked by GC locker and that can't
948 // be the case here since we only call this when already completed one gc.
949 assert(success, "invariant");
950 return success;
951 }
952
953 void G1CollectedHeap::resize_heap_if_necessary() {
954 assert_at_safepoint_on_vm_thread();
955
956 bool should_expand;
957 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
958
959 if (resize_amount == 0) {
960 return;
961 } else if (should_expand) {
962 expand(resize_amount, _workers);
963 } else {
964 shrink(resize_amount);
965 }
966 }
967
968 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
969 bool do_gc,
970 bool maximal_compaction,
971 bool expect_null_mutator_alloc_region,
972 bool* gc_succeeded) {
973 *gc_succeeded = true;
974 // Let's attempt the allocation first.
975 HeapWord* result =
976 attempt_allocation_at_safepoint(word_size,
977 expect_null_mutator_alloc_region);
978 if (result != nullptr) {
979 return result;
980 }
981
982 // In a G1 heap, we're supposed to keep allocation from failing by
983 // incremental pauses. Therefore, at least for now, we'll favor
984 // expansion over collection. (This might change in the future if we can
985 // do something smarter than full collection to satisfy a failed alloc.)
986 result = expand_and_allocate(word_size);
987 if (result != nullptr) {
988 return result;
989 }
990
991 if (do_gc) {
992 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
993 // Expansion didn't work, we'll try to do a Full GC.
994 // If maximal_compaction is set we clear all soft references and don't
995 // allow any dead wood to be left on the heap.
996 if (maximal_compaction) {
997 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
998 } else {
999 log_info(gc, ergo)("Attempting full compaction");
1000 }
1001 *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ ,
1002 maximal_compaction /* do_maximal_compaction */);
1003 }
1004
1005 return nullptr;
1006 }
1007
1008 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1009 bool* succeeded) {
1010 assert_at_safepoint_on_vm_thread();
1011
1012 // Attempts to allocate followed by Full GC.
1013 HeapWord* result =
1014 satisfy_failed_allocation_helper(word_size,
1015 true, /* do_gc */
1016 false, /* maximum_collection */
1017 false, /* expect_null_mutator_alloc_region */
1018 succeeded);
1019
1020 if (result != nullptr || !*succeeded) {
1021 return result;
1022 }
1023
1024 // Attempts to allocate followed by Full GC that will collect all soft references.
1025 result = satisfy_failed_allocation_helper(word_size,
1026 true, /* do_gc */
1027 true, /* maximum_collection */
1028 true, /* expect_null_mutator_alloc_region */
1029 succeeded);
1030
1031 if (result != nullptr || !*succeeded) {
1032 return result;
1033 }
1034
1035 // Attempts to allocate, no GC
1036 result = satisfy_failed_allocation_helper(word_size,
1037 false, /* do_gc */
1038 false, /* maximum_collection */
1039 true, /* expect_null_mutator_alloc_region */
1040 succeeded);
1041
1042 if (result != nullptr) {
1043 return result;
1044 }
1045
1046 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1047 "Flag should have been handled and cleared prior to this point");
1048
1049 // What else? We might try synchronous finalization later. If the total
1050 // space available is large enough for the allocation, then a more
1051 // complete compaction phase than we've tried so far might be
1052 // appropriate.
1053 return nullptr;
1054 }
1055
1056 // Attempting to expand the heap sufficiently
1057 // to support an allocation of the given "word_size". If
1058 // successful, perform the allocation and return the address of the
1059 // allocated block, or else null.
1060
1061 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1062 assert_at_safepoint_on_vm_thread();
1063
1064 _verifier->verify_region_sets_optional();
1065
1066 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1067 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1068 word_size * HeapWordSize);
1069
1070
1071 if (expand(expand_bytes, _workers)) {
1072 _hrm.verify_optional();
1073 _verifier->verify_region_sets_optional();
1074 return attempt_allocation_at_safepoint(word_size,
1075 false /* expect_null_mutator_alloc_region */);
1076 }
1077 return nullptr;
1078 }
1079
1080 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1081 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1082 aligned_expand_bytes = align_up(aligned_expand_bytes,
1083 HeapRegion::GrainBytes);
1084
1085 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1086 expand_bytes, aligned_expand_bytes);
1087
1088 if (is_maximal_no_gc()) {
1089 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1090 return false;
1091 }
1092
1093 double expand_heap_start_time_sec = os::elapsedTime();
1094 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1095 assert(regions_to_expand > 0, "Must expand by at least one region");
1096
1097 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1098 if (expand_time_ms != nullptr) {
1099 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1100 }
1101
1102 assert(expanded_by > 0, "must have failed during commit.");
1103
1104 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1105 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1106 policy()->record_new_heap_size(num_regions());
1107
1108 return true;
1109 }
1110
1111 bool G1CollectedHeap::expand_single_region(uint node_index) {
1112 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1113
1114 if (expanded_by == 0) {
1115 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1116 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1117 return false;
1118 }
1119
1120 policy()->record_new_heap_size(num_regions());
1121 return true;
1122 }
1123
1124 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1125 size_t aligned_shrink_bytes =
1126 ReservedSpace::page_align_size_down(shrink_bytes);
1127 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1128 HeapRegion::GrainBytes);
1129 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1130
1131 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1132 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1133
1134 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",
1135 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1136 if (num_regions_removed > 0) {
1137 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1138 policy()->record_new_heap_size(num_regions());
1139 } else {
1140 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1141 }
1142 }
1143
1144 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1145 _verifier->verify_region_sets_optional();
1146
1147 // We should only reach here at the end of a Full GC or during Remark which
1148 // means we should not not be holding to any GC alloc regions. The method
1149 // below will make sure of that and do any remaining clean up.
1150 _allocator->abandon_gc_alloc_regions();
1151
1152 // Instead of tearing down / rebuilding the free lists here, we
1153 // could instead use the remove_all_pending() method on free_list to
1154 // remove only the ones that we need to remove.
1155 _hrm.remove_all_free_regions();
1156 shrink_helper(shrink_bytes);
1157 rebuild_region_sets(true /* free_list_only */);
1158
1159 _hrm.verify_optional();
1160 _verifier->verify_region_sets_optional();
1161 }
1162
1163 class OldRegionSetChecker : public HeapRegionSetChecker {
1164 public:
1165 void check_mt_safety() {
1166 // Master Old Set MT safety protocol:
1167 // (a) If we're at a safepoint, operations on the master old set
1168 // should be invoked:
1169 // - by the VM thread (which will serialize them), or
1170 // - by the GC workers while holding the FreeList_lock, if we're
1171 // at a safepoint for an evacuation pause (this lock is taken
1172 // anyway when an GC alloc region is retired so that a new one
1173 // is allocated from the free list), or
1174 // - by the GC workers while holding the OldSets_lock, if we're at a
1175 // safepoint for a cleanup pause.
1176 // (b) If we're not at a safepoint, operations on the master old set
1177 // should be invoked while holding the Heap_lock.
1178
1179 if (SafepointSynchronize::is_at_safepoint()) {
1180 guarantee(Thread::current()->is_VM_thread() ||
1181 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1182 "master old set MT safety protocol at a safepoint");
1183 } else {
1184 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1185 }
1186 }
1187 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1188 const char* get_description() { return "Old Regions"; }
1189 };
1190
1191 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1192 public:
1193 void check_mt_safety() {
1194 // Humongous Set MT safety protocol:
1195 // (a) If we're at a safepoint, operations on the master humongous
1196 // set should be invoked by either the VM thread (which will
1197 // serialize them) or by the GC workers while holding the
1198 // OldSets_lock.
1199 // (b) If we're not at a safepoint, operations on the master
1200 // humongous set should be invoked while holding the Heap_lock.
1201
1202 if (SafepointSynchronize::is_at_safepoint()) {
1203 guarantee(Thread::current()->is_VM_thread() ||
1204 OldSets_lock->owned_by_self(),
1205 "master humongous set MT safety protocol at a safepoint");
1206 } else {
1207 guarantee(Heap_lock->owned_by_self(),
1208 "master humongous set MT safety protocol outside a safepoint");
1209 }
1210 }
1211 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1212 const char* get_description() { return "Humongous Regions"; }
1213 };
1214
1215 G1CollectedHeap::G1CollectedHeap() :
1216 CollectedHeap(),
1217 _service_thread(nullptr),
1218 _periodic_gc_task(nullptr),
1219 _free_arena_memory_task(nullptr),
1220 _workers(nullptr),
1221 _card_table(nullptr),
1222 _collection_pause_end(Ticks::now()),
1223 _soft_ref_policy(),
1224 _old_set("Old Region Set", new OldRegionSetChecker()),
1225 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1226 _bot(nullptr),
1227 _listener(),
1228 _numa(G1NUMA::create()),
1229 _hrm(),
1230 _allocator(nullptr),
1231 _evac_failure_injector(),
1232 _verifier(nullptr),
1233 _summary_bytes_used(0),
1234 _bytes_used_during_gc(0),
1235 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1236 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1237 _monitoring_support(nullptr),
1238 _num_humongous_objects(0),
1239 _num_humongous_reclaim_candidates(0),
1240 _hr_printer(),
1241 _collector_state(),
1242 _old_marking_cycles_started(0),
1243 _old_marking_cycles_completed(0),
1244 _eden(),
1245 _survivor(),
1246 _gc_timer_stw(new STWGCTimer()),
1247 _gc_tracer_stw(new G1NewTracer()),
1248 _policy(new G1Policy(_gc_timer_stw)),
1249 _heap_sizing_policy(nullptr),
1250 _collection_set(this, _policy),
1251 _rem_set(nullptr),
1252 _card_set_config(),
1253 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1254 _cm(nullptr),
1255 _cm_thread(nullptr),
1256 _cr(nullptr),
1257 _task_queues(nullptr),
1258 _ref_processor_stw(nullptr),
1259 _is_alive_closure_stw(this),
1260 _is_subject_to_discovery_stw(this),
1261 _ref_processor_cm(nullptr),
1262 _is_alive_closure_cm(this),
1263 _is_subject_to_discovery_cm(this),
1264 _region_attr() {
1265
1266 _verifier = new G1HeapVerifier(this);
1267
1268 _allocator = new G1Allocator(this);
1269
1270 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1271
1272 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1273
1274 // Override the default _filler_array_max_size so that no humongous filler
1275 // objects are created.
1276 _filler_array_max_size = _humongous_object_threshold_in_words;
1277
1278 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1279 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1280
1281 uint n_queues = ParallelGCThreads;
1282 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1283
1284 for (uint i = 0; i < n_queues; i++) {
1285 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1286 _task_queues->register_queue(i, q);
1287 }
1288
1289 _gc_tracer_stw->initialize();
1290
1291 guarantee(_task_queues != nullptr, "task_queues allocation failure.");
1292 }
1293
1294 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1295 size_t size,
1296 size_t translation_factor) {
1297 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1298 // Allocate a new reserved space, preferring to use large pages.
1299 ReservedSpace rs(size, preferred_page_size);
1300 size_t page_size = rs.page_size();
1301 G1RegionToSpaceMapper* result =
1302 G1RegionToSpaceMapper::create_mapper(rs,
1303 size,
1304 page_size,
1305 HeapRegion::GrainBytes,
1306 translation_factor,
1307 mtGC);
1308
1309 os::trace_page_sizes_for_requested_size(description,
1310 size,
1311 preferred_page_size,
1312 rs.base(),
1313 rs.size(),
1314 page_size);
1315
1316 return result;
1317 }
1318
1319 jint G1CollectedHeap::initialize_concurrent_refinement() {
1320 jint ecode = JNI_OK;
1321 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1322 return ecode;
1323 }
1324
1325 jint G1CollectedHeap::initialize_service_thread() {
1326 _service_thread = new G1ServiceThread();
1327 if (_service_thread->osthread() == nullptr) {
1328 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1329 return JNI_ENOMEM;
1330 }
1331 return JNI_OK;
1332 }
1333
1334 jint G1CollectedHeap::initialize() {
1335
1336 // Necessary to satisfy locking discipline assertions.
1337
1338 MutexLocker x(Heap_lock);
1339
1340 // While there are no constraints in the GC code that HeapWordSize
1341 // be any particular value, there are multiple other areas in the
1342 // system which believe this to be true (e.g. oop->object_size in some
1343 // cases incorrectly returns the size in wordSize units rather than
1344 // HeapWordSize).
1345 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1346
1347 size_t init_byte_size = InitialHeapSize;
1348 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1349
1350 // Ensure that the sizes are properly aligned.
1351 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1352 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1353 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1354
1355 // Reserve the maximum.
1356
1357 // When compressed oops are enabled, the preferred heap base
1358 // is calculated by subtracting the requested size from the
1359 // 32Gb boundary and using the result as the base address for
1360 // heap reservation. If the requested size is not aligned to
1361 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1362 // into the ReservedHeapSpace constructor) then the actual
1363 // base of the reserved heap may end up differing from the
1364 // address that was requested (i.e. the preferred heap base).
1365 // If this happens then we could end up using a non-optimal
1366 // compressed oops mode.
1367
1368 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1369 HeapAlignment);
1370
1371 initialize_reserved_region(heap_rs);
1372
1373 // Create the barrier set for the entire reserved region.
1374 G1CardTable* ct = new G1CardTable(heap_rs.region());
1375 G1BarrierSet* bs = new G1BarrierSet(ct);
1376 bs->initialize();
1377 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1378 BarrierSet::set_barrier_set(bs);
1379 _card_table = ct;
1380
1381 {
1382 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1383 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1384 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1385 }
1386
1387 // Create space mappers.
1388 size_t page_size = heap_rs.page_size();
1389 G1RegionToSpaceMapper* heap_storage =
1390 G1RegionToSpaceMapper::create_mapper(heap_rs,
1391 heap_rs.size(),
1392 page_size,
1393 HeapRegion::GrainBytes,
1394 1,
1395 mtJavaHeap);
1396 if(heap_storage == nullptr) {
1397 vm_shutdown_during_initialization("Could not initialize G1 heap");
1398 return JNI_ERR;
1399 }
1400
1401 os::trace_page_sizes("Heap",
1402 MinHeapSize,
1403 reserved_byte_size,
1404 heap_rs.base(),
1405 heap_rs.size(),
1406 page_size);
1407 heap_storage->set_mapping_changed_listener(&_listener);
1408
1409 // Create storage for the BOT, card table and the bitmap.
1410 G1RegionToSpaceMapper* bot_storage =
1411 create_aux_memory_mapper("Block Offset Table",
1412 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1413 G1BlockOffsetTable::heap_map_factor());
1414
1415 G1RegionToSpaceMapper* cardtable_storage =
1416 create_aux_memory_mapper("Card Table",
1417 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1418 G1CardTable::heap_map_factor());
1419
1420 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1421 G1RegionToSpaceMapper* bitmap_storage =
1422 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1423
1424 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1425 _card_table->initialize(cardtable_storage);
1426
1427 // 6843694 - ensure that the maximum region index can fit
1428 // in the remembered set structures.
1429 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1430 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1431
1432 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1433 // start within the first card.
1434 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1435 G1FromCardCache::initialize(max_reserved_regions());
1436 // Also create a G1 rem set.
1437 _rem_set = new G1RemSet(this, _card_table);
1438 _rem_set->initialize(max_reserved_regions());
1439
1440 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1441 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1442 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1443 "too many cards per region");
1444
1445 HeapRegionRemSet::initialize(_reserved);
1446
1447 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1448
1449 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1450
1451 {
1452 size_t granularity = HeapRegion::GrainBytes;
1453
1454 _region_attr.initialize(reserved(), granularity);
1455 }
1456
1457 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1458 if (_workers == nullptr) {
1459 return JNI_ENOMEM;
1460 }
1461 _workers->initialize_workers();
1462
1463 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1464
1465 // Create the G1ConcurrentMark data structure and thread.
1466 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1467 _cm = new G1ConcurrentMark(this, bitmap_storage);
1468 _cm_thread = _cm->cm_thread();
1469
1470 // Now expand into the initial heap size.
1471 if (!expand(init_byte_size, _workers)) {
1472 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1473 return JNI_ENOMEM;
1474 }
1475
1476 // Perform any initialization actions delegated to the policy.
1477 policy()->init(this, &_collection_set);
1478
1479 jint ecode = initialize_concurrent_refinement();
1480 if (ecode != JNI_OK) {
1481 return ecode;
1482 }
1483
1484 ecode = initialize_service_thread();
1485 if (ecode != JNI_OK) {
1486 return ecode;
1487 }
1488
1489 // Create and schedule the periodic gc task on the service thread.
1490 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1491 _service_thread->register_task(_periodic_gc_task);
1492
1493 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1494 _service_thread->register_task(_free_arena_memory_task);
1495
1496 // Here we allocate the dummy HeapRegion that is required by the
1497 // G1AllocRegion class.
1498 HeapRegion* dummy_region = _hrm.get_dummy_region();
1499
1500 // We'll re-use the same region whether the alloc region will
1501 // require BOT updates or not and, if it doesn't, then a non-young
1502 // region will complain that it cannot support allocations without
1503 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1504 dummy_region->set_eden();
1505 // Make sure it's full.
1506 dummy_region->set_top(dummy_region->end());
1507 G1AllocRegion::setup(this, dummy_region);
1508
1509 _allocator->init_mutator_alloc_regions();
1510
1511 // Do create of the monitoring and management support so that
1512 // values in the heap have been properly initialized.
1513 _monitoring_support = new G1MonitoringSupport(this);
1514
1515 _collection_set.initialize(max_reserved_regions());
1516
1517 evac_failure_injector()->reset();
1518
1519 G1InitLogger::print();
1520
1521 GCForwarding::initialize(heap_rs.region(), HeapRegion::GrainWords);
1522
1523 return JNI_OK;
1524 }
1525
1526 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1527 return _cm_thread->should_terminate();
1528 }
1529
1530 void G1CollectedHeap::stop() {
1531 // Stop all concurrent threads. We do this to make sure these threads
1532 // do not continue to execute and access resources (e.g. logging)
1533 // that are destroyed during shutdown.
1534 _cr->stop();
1535 _service_thread->stop();
1536 _cm_thread->stop();
1537 }
1538
1539 void G1CollectedHeap::safepoint_synchronize_begin() {
1540 SuspendibleThreadSet::synchronize();
1541 }
1542
1543 void G1CollectedHeap::safepoint_synchronize_end() {
1544 SuspendibleThreadSet::desynchronize();
1545 }
1546
1547 void G1CollectedHeap::post_initialize() {
1548 CollectedHeap::post_initialize();
1549 ref_processing_init();
1550 }
1551
1552 void G1CollectedHeap::ref_processing_init() {
1553 // Reference processing in G1 currently works as follows:
1554 //
1555 // * There are two reference processor instances. One is
1556 // used to record and process discovered references
1557 // during concurrent marking; the other is used to
1558 // record and process references during STW pauses
1559 // (both full and incremental).
1560 // * Both ref processors need to 'span' the entire heap as
1561 // the regions in the collection set may be dotted around.
1562 //
1563 // * For the concurrent marking ref processor:
1564 // * Reference discovery is enabled at concurrent start.
1565 // * Reference discovery is disabled and the discovered
1566 // references processed etc during remarking.
1567 // * Reference discovery is MT (see below).
1568 // * Reference discovery requires a barrier (see below).
1569 // * Reference processing may or may not be MT
1570 // (depending on the value of ParallelRefProcEnabled
1571 // and ParallelGCThreads).
1572 // * A full GC disables reference discovery by the CM
1573 // ref processor and abandons any entries on it's
1574 // discovered lists.
1575 //
1576 // * For the STW processor:
1577 // * Non MT discovery is enabled at the start of a full GC.
1578 // * Processing and enqueueing during a full GC is non-MT.
1579 // * During a full GC, references are processed after marking.
1580 //
1581 // * Discovery (may or may not be MT) is enabled at the start
1582 // of an incremental evacuation pause.
1583 // * References are processed near the end of a STW evacuation pause.
1584 // * For both types of GC:
1585 // * Discovery is atomic - i.e. not concurrent.
1586 // * Reference discovery will not need a barrier.
1587
1588 // Concurrent Mark ref processor
1589 _ref_processor_cm =
1590 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1591 ParallelGCThreads, // degree of mt processing
1592 // We discover with the gc worker threads during Remark, so both
1593 // thread counts must be considered for discovery.
1594 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1595 true, // Reference discovery is concurrent
1596 &_is_alive_closure_cm); // is alive closure
1597
1598 // STW ref processor
1599 _ref_processor_stw =
1600 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1601 ParallelGCThreads, // degree of mt processing
1602 ParallelGCThreads, // degree of mt discovery
1603 false, // Reference discovery is not concurrent
1604 &_is_alive_closure_stw); // is alive closure
1605 }
1606
1607 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1608 return &_soft_ref_policy;
1609 }
1610
1611 size_t G1CollectedHeap::capacity() const {
1612 return _hrm.length() * HeapRegion::GrainBytes;
1613 }
1614
1615 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1616 return _hrm.total_free_bytes();
1617 }
1618
1619 // Computes the sum of the storage used by the various regions.
1620 size_t G1CollectedHeap::used() const {
1621 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1622 return result;
1623 }
1624
1625 size_t G1CollectedHeap::used_unlocked() const {
1626 return _summary_bytes_used;
1627 }
1628
1629 class SumUsedClosure: public HeapRegionClosure {
1630 size_t _used;
1631 public:
1632 SumUsedClosure() : _used(0) {}
1633 bool do_heap_region(HeapRegion* r) {
1634 _used += r->used();
1635 return false;
1636 }
1637 size_t result() { return _used; }
1638 };
1639
1640 size_t G1CollectedHeap::recalculate_used() const {
1641 SumUsedClosure blk;
1642 heap_region_iterate(&blk);
1643 return blk.result();
1644 }
1645
1646 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1647 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1648 }
1649
1650 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1651 switch (cause) {
1652 case GCCause::_g1_humongous_allocation: return true;
1653 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1654 case GCCause::_wb_breakpoint: return true;
1655 case GCCause::_codecache_GC_aggressive: return true;
1656 case GCCause::_codecache_GC_threshold: return true;
1657 default: return is_user_requested_concurrent_full_gc(cause);
1658 }
1659 }
1660
1661 void G1CollectedHeap::increment_old_marking_cycles_started() {
1662 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1663 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1664 "Wrong marking cycle count (started: %d, completed: %d)",
1665 _old_marking_cycles_started, _old_marking_cycles_completed);
1666
1667 _old_marking_cycles_started++;
1668 }
1669
1670 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1671 bool whole_heap_examined) {
1672 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1673
1674 // We assume that if concurrent == true, then the caller is a
1675 // concurrent thread that was joined the Suspendible Thread
1676 // Set. If there's ever a cheap way to check this, we should add an
1677 // assert here.
1678
1679 // Given that this method is called at the end of a Full GC or of a
1680 // concurrent cycle, and those can be nested (i.e., a Full GC can
1681 // interrupt a concurrent cycle), the number of full collections
1682 // completed should be either one (in the case where there was no
1683 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1684 // behind the number of full collections started.
1685
1686 // This is the case for the inner caller, i.e. a Full GC.
1687 assert(concurrent ||
1688 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1689 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1690 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1691 "is inconsistent with _old_marking_cycles_completed = %u",
1692 _old_marking_cycles_started, _old_marking_cycles_completed);
1693
1694 // This is the case for the outer caller, i.e. the concurrent cycle.
1695 assert(!concurrent ||
1696 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1697 "for outer caller (concurrent cycle): "
1698 "_old_marking_cycles_started = %u "
1699 "is inconsistent with _old_marking_cycles_completed = %u",
1700 _old_marking_cycles_started, _old_marking_cycles_completed);
1701
1702 _old_marking_cycles_completed += 1;
1703 if (whole_heap_examined) {
1704 // Signal that we have completed a visit to all live objects.
1705 record_whole_heap_examined_timestamp();
1706 }
1707
1708 // We need to clear the "in_progress" flag in the CM thread before
1709 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1710 // is set) so that if a waiter requests another System.gc() it doesn't
1711 // incorrectly see that a marking cycle is still in progress.
1712 if (concurrent) {
1713 _cm_thread->set_idle();
1714 }
1715
1716 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1717 // for a full GC to finish that their wait is over.
1718 ml.notify_all();
1719 }
1720
1721 // Helper for collect().
1722 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1723 MutexLocker ml(Heap_lock);
1724 return G1GCCounters(g1h);
1725 }
1726
1727 void G1CollectedHeap::collect(GCCause::Cause cause) {
1728 try_collect(cause, collection_counters(this));
1729 }
1730
1731 // Return true if (x < y) with allowance for wraparound.
1732 static bool gc_counter_less_than(uint x, uint y) {
1733 return (x - y) > (UINT_MAX/2);
1734 }
1735
1736 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1737 // Macro so msg printing is format-checked.
1738 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1739 do { \
1740 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1741 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1742 ResourceMark rm; /* For thread name. */ \
1743 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1744 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1745 Thread::current()->name(), \
1746 GCCause::to_string(cause)); \
1747 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1748 } \
1749 } while (0)
1750
1751 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1752 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1753
1754 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1755 uint gc_counter,
1756 uint old_marking_started_before) {
1757 assert_heap_not_locked();
1758 assert(should_do_concurrent_full_gc(cause),
1759 "Non-concurrent cause %s", GCCause::to_string(cause));
1760
1761 for (uint i = 1; true; ++i) {
1762 // Try to schedule concurrent start evacuation pause that will
1763 // start a concurrent cycle.
1764 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1765 VM_G1TryInitiateConcMark op(gc_counter, cause);
1766 VMThread::execute(&op);
1767
1768 // Request is trivially finished.
1769 if (cause == GCCause::_g1_periodic_collection) {
1770 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1771 return op.gc_succeeded();
1772 }
1773
1774 // If VMOp skipped initiating concurrent marking cycle because
1775 // we're terminating, then we're done.
1776 if (op.terminating()) {
1777 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1778 return false;
1779 }
1780
1781 // Lock to get consistent set of values.
1782 uint old_marking_started_after;
1783 uint old_marking_completed_after;
1784 {
1785 MutexLocker ml(Heap_lock);
1786 // Update gc_counter for retrying VMOp if needed. Captured here to be
1787 // consistent with the values we use below for termination tests. If
1788 // a retry is needed after a possible wait, and another collection
1789 // occurs in the meantime, it will cause our retry to be skipped and
1790 // we'll recheck for termination with updated conditions from that
1791 // more recent collection. That's what we want, rather than having
1792 // our retry possibly perform an unnecessary collection.
1793 gc_counter = total_collections();
1794 old_marking_started_after = _old_marking_cycles_started;
1795 old_marking_completed_after = _old_marking_cycles_completed;
1796 }
1797
1798 if (cause == GCCause::_wb_breakpoint) {
1799 if (op.gc_succeeded()) {
1800 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1801 return true;
1802 }
1803 // When _wb_breakpoint there can't be another cycle or deferred.
1804 assert(!op.cycle_already_in_progress(), "invariant");
1805 assert(!op.whitebox_attached(), "invariant");
1806 // Concurrent cycle attempt might have been cancelled by some other
1807 // collection, so retry. Unlike other cases below, we want to retry
1808 // even if cancelled by a STW full collection, because we really want
1809 // to start a concurrent cycle.
1810 if (old_marking_started_before != old_marking_started_after) {
1811 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1812 old_marking_started_before = old_marking_started_after;
1813 }
1814 } else if (!GCCause::is_user_requested_gc(cause)) {
1815 // For an "automatic" (not user-requested) collection, we just need to
1816 // ensure that progress is made.
1817 //
1818 // Request is finished if any of
1819 // (1) the VMOp successfully performed a GC,
1820 // (2) a concurrent cycle was already in progress,
1821 // (3) whitebox is controlling concurrent cycles,
1822 // (4) a new cycle was started (by this thread or some other), or
1823 // (5) a Full GC was performed.
1824 // Cases (4) and (5) are detected together by a change to
1825 // _old_marking_cycles_started.
1826 //
1827 // Note that (1) does not imply (4). If we're still in the mixed
1828 // phase of an earlier concurrent collection, the request to make the
1829 // collection a concurrent start won't be honored. If we don't check for
1830 // both conditions we'll spin doing back-to-back collections.
1831 if (op.gc_succeeded() ||
1832 op.cycle_already_in_progress() ||
1833 op.whitebox_attached() ||
1834 (old_marking_started_before != old_marking_started_after)) {
1835 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1836 return true;
1837 }
1838 } else { // User-requested GC.
1839 // For a user-requested collection, we want to ensure that a complete
1840 // full collection has been performed before returning, but without
1841 // waiting for more than needed.
1842
1843 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1844 // new cycle was started. That's good, because it's not clear what we
1845 // should do otherwise. Trying again just does back to back GCs.
1846 // Can't wait for someone else to start a cycle. And returning fails
1847 // to meet the goal of ensuring a full collection was performed.
1848 assert(!op.gc_succeeded() ||
1849 (old_marking_started_before != old_marking_started_after),
1850 "invariant: succeeded %s, started before %u, started after %u",
1851 BOOL_TO_STR(op.gc_succeeded()),
1852 old_marking_started_before, old_marking_started_after);
1853
1854 // Request is finished if a full collection (concurrent or stw)
1855 // was started after this request and has completed, e.g.
1856 // started_before < completed_after.
1857 if (gc_counter_less_than(old_marking_started_before,
1858 old_marking_completed_after)) {
1859 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1860 return true;
1861 }
1862
1863 if (old_marking_started_after != old_marking_completed_after) {
1864 // If there is an in-progress cycle (possibly started by us), then
1865 // wait for that cycle to complete, e.g.
1866 // while completed_now < started_after.
1867 LOG_COLLECT_CONCURRENTLY(cause, "wait");
1868 MonitorLocker ml(G1OldGCCount_lock);
1869 while (gc_counter_less_than(_old_marking_cycles_completed,
1870 old_marking_started_after)) {
1871 ml.wait();
1872 }
1873 // Request is finished if the collection we just waited for was
1874 // started after this request.
1875 if (old_marking_started_before != old_marking_started_after) {
1876 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
1877 return true;
1878 }
1879 }
1880
1881 // If VMOp was successful then it started a new cycle that the above
1882 // wait &etc should have recognized as finishing this request. This
1883 // differs from a non-user-request, where gc_succeeded does not imply
1884 // a new cycle was started.
1885 assert(!op.gc_succeeded(), "invariant");
1886
1887 if (op.cycle_already_in_progress()) {
1888 // If VMOp failed because a cycle was already in progress, it
1889 // is now complete. But it didn't finish this user-requested
1890 // GC, so try again.
1891 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
1892 continue;
1893 } else if (op.whitebox_attached()) {
1894 // If WhiteBox wants control, wait for notification of a state
1895 // change in the controller, then try again. Don't wait for
1896 // release of control, since collections may complete while in
1897 // control. Note: This won't recognize a STW full collection
1898 // while waiting; we can't wait on multiple monitors.
1899 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
1900 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
1901 if (ConcurrentGCBreakpoints::is_controlled()) {
1902 ml.wait();
1903 }
1904 continue;
1905 }
1906 }
1907
1908 // Collection failed and should be retried.
1909 assert(op.transient_failure(), "invariant");
1910
1911 if (GCLocker::is_active_and_needs_gc()) {
1912 // If GCLocker is active, wait until clear before retrying.
1913 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
1914 GCLocker::stall_until_clear();
1915 }
1916
1917 LOG_COLLECT_CONCURRENTLY(cause, "retry");
1918 }
1919 }
1920
1921 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause,
1922 const G1GCCounters& counters_before) {
1923 assert_heap_not_locked();
1924
1925 while(true) {
1926 VM_G1CollectFull op(counters_before.total_collections(),
1927 counters_before.total_full_collections(),
1928 cause);
1929 VMThread::execute(&op);
1930
1931 // Request is trivially finished.
1932 if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) {
1933 return op.gc_succeeded();
1934 }
1935
1936 {
1937 MutexLocker ml(Heap_lock);
1938 if (counters_before.total_full_collections() != total_full_collections()) {
1939 return true;
1940 }
1941 }
1942
1943 if (GCLocker::is_active_and_needs_gc()) {
1944 // If GCLocker is active, wait until clear before retrying.
1945 GCLocker::stall_until_clear();
1946 }
1947 }
1948 }
1949
1950 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
1951 const G1GCCounters& counters_before) {
1952 if (should_do_concurrent_full_gc(cause)) {
1953 return try_collect_concurrently(cause,
1954 counters_before.total_collections(),
1955 counters_before.old_marking_cycles_started());
1956 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
1957 // Indicate failure to be consistent with VMOp failure due to
1958 // another collection slipping in after our gc_count but before
1959 // our request is processed.
1960 return false;
1961 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
1962 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1963
1964 // Schedule a standard evacuation pause. We're setting word_size
1965 // to 0 which means that we are not requesting a post-GC allocation.
1966 VM_G1CollectForAllocation op(0, /* word_size */
1967 counters_before.total_collections(),
1968 cause);
1969 VMThread::execute(&op);
1970 return op.gc_succeeded();
1971 } else {
1972 // Schedule a Full GC.
1973 return try_collect_fullgc(cause, counters_before);
1974 }
1975 }
1976
1977 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
1978 GCCauseSetter x(this, gc_cause);
1979
1980 // At this point we are supposed to start a concurrent cycle. We
1981 // will do so if one is not already in progress.
1982 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
1983 if (should_start) {
1984 do_collection_pause_at_safepoint();
1985 }
1986 }
1987
1988 bool G1CollectedHeap::is_in(const void* p) const {
1989 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
1990 }
1991
1992 // Iteration functions.
1993
1994 // Iterates an ObjectClosure over all objects within a HeapRegion.
1995
1996 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1997 ObjectClosure* _cl;
1998 public:
1999 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2000 bool do_heap_region(HeapRegion* r) {
2001 if (!r->is_continues_humongous()) {
2002 r->object_iterate(_cl);
2003 }
2004 return false;
2005 }
2006 };
2007
2008 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2009 IterateObjectClosureRegionClosure blk(cl);
2010 heap_region_iterate(&blk);
2011 }
2012
2013 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2014 private:
2015 G1CollectedHeap* _heap;
2016 HeapRegionClaimer _claimer;
2017
2018 public:
2019 G1ParallelObjectIterator(uint thread_num) :
2020 _heap(G1CollectedHeap::heap()),
2021 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2022
2023 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2024 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2025 }
2026 };
2027
2028 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2029 return new G1ParallelObjectIterator(thread_num);
2030 }
2031
2032 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2033 IterateObjectClosureRegionClosure blk(cl);
2034 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2035 }
2036
2037 void G1CollectedHeap::keep_alive(oop obj) {
2038 G1BarrierSet::enqueue_preloaded(obj);
2039 }
2040
2041 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2042 _hrm.iterate(cl);
2043 }
2044
2045 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2046 _hrm.iterate(cl);
2047 }
2048
2049 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2050 HeapRegionClaimer *hrclaimer,
2051 uint worker_id) const {
2052 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2053 }
2054
2055 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2056 HeapRegionClaimer *hrclaimer) const {
2057 _hrm.par_iterate(cl, hrclaimer, 0);
2058 }
2059
2060 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2061 _collection_set.iterate(cl);
2062 }
2063
2064 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2065 HeapRegionClaimer* hr_claimer,
2066 uint worker_id) {
2067 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2068 }
2069
2070 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2071 HeapRegionClaimer* hr_claimer,
2072 uint worker_id) {
2073 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2074 }
2075
2076 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2077 HeapRegionClaimer* hr_claimer,
2078 const uint regions[],
2079 size_t length,
2080 uint worker_id) const {
2081 assert_at_safepoint();
2082 if (length == 0) {
2083 return;
2084 }
2085 uint total_workers = workers()->active_workers();
2086
2087 size_t start_pos = (worker_id * length) / total_workers;
2088 size_t cur_pos = start_pos;
2089
2090 do {
2091 uint region_idx = regions[cur_pos];
2092 if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) {
2093 HeapRegion* r = region_at(region_idx);
2094 bool result = cl->do_heap_region(r);
2095 guarantee(!result, "Must not cancel iteration");
2096 }
2097
2098 cur_pos++;
2099 if (cur_pos == length) {
2100 cur_pos = 0;
2101 }
2102 } while (cur_pos != start_pos);
2103 }
2104
2105 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2106 HeapRegion* hr = heap_region_containing(addr);
2107 // The CollectedHeap API requires us to not fail for any given address within
2108 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2109 // outside of the allocated area.
2110 if (addr >= hr->top()) {
2111 return nullptr;
2112 }
2113 return hr->block_start(addr);
2114 }
2115
2116 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2117 HeapRegion* hr = heap_region_containing(addr);
2118 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2119 }
2120
2121 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2122 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2123 }
2124
2125 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2126 return _eden.length() * HeapRegion::GrainBytes;
2127 }
2128
2129 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2130 // must be equal to the humongous object limit.
2131 size_t G1CollectedHeap::max_tlab_size() const {
2132 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2133 }
2134
2135 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2136 return _allocator->unsafe_max_tlab_alloc();
2137 }
2138
2139 size_t G1CollectedHeap::max_capacity() const {
2140 return max_regions() * HeapRegion::GrainBytes;
2141 }
2142
2143 void G1CollectedHeap::prepare_for_verify() {
2144 _verifier->prepare_for_verify();
2145 }
2146
2147 void G1CollectedHeap::verify(VerifyOption vo) {
2148 _verifier->verify(vo);
2149 }
2150
2151 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2152 return true;
2153 }
2154
2155 class PrintRegionClosure: public HeapRegionClosure {
2156 outputStream* _st;
2157 public:
2158 PrintRegionClosure(outputStream* st) : _st(st) {}
2159 bool do_heap_region(HeapRegion* r) {
2160 r->print_on(_st);
2161 return false;
2162 }
2163 };
2164
2165 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2166 const HeapRegion* hr,
2167 const VerifyOption vo) const {
2168 switch (vo) {
2169 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2170 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2171 default: ShouldNotReachHere();
2172 }
2173 return false; // keep some compilers happy
2174 }
2175
2176 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2177 const VerifyOption vo) const {
2178 switch (vo) {
2179 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2180 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2181 default: ShouldNotReachHere();
2182 }
2183 return false; // keep some compilers happy
2184 }
2185
2186 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) {
2187 GCLocker::lock_critical(thread);
2188 }
2189
2190 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
2191 GCLocker::unlock_critical(thread);
2192 }
2193
2194 void G1CollectedHeap::print_heap_regions() const {
2195 LogTarget(Trace, gc, heap, region) lt;
2196 if (lt.is_enabled()) {
2197 LogStream ls(lt);
2198 print_regions_on(&ls);
2199 }
2200 }
2201
2202 void G1CollectedHeap::print_on(outputStream* st) const {
2203 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2204 st->print(" %-20s", "garbage-first heap");
2205 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2206 capacity()/K, heap_used/K);
2207 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2208 p2i(_hrm.reserved().start()),
2209 p2i(_hrm.reserved().end()));
2210 st->cr();
2211 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2212 uint young_regions = young_regions_count();
2213 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2214 (size_t) young_regions * HeapRegion::GrainBytes / K);
2215 uint survivor_regions = survivor_regions_count();
2216 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2217 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2218 st->cr();
2219 if (_numa->is_enabled()) {
2220 uint num_nodes = _numa->num_active_nodes();
2221 st->print(" remaining free region(s) on each NUMA node: ");
2222 const int* node_ids = _numa->node_ids();
2223 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2224 uint num_free_regions = _hrm.num_free_regions(node_index);
2225 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2226 }
2227 st->cr();
2228 }
2229 MetaspaceUtils::print_on(st);
2230 }
2231
2232 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2233 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2234 "HS=humongous(starts), HC=humongous(continues), "
2235 "CS=collection set, F=free, "
2236 "TAMS=top-at-mark-start, "
2237 "PB=parsable bottom");
2238 PrintRegionClosure blk(st);
2239 heap_region_iterate(&blk);
2240 }
2241
2242 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2243 print_on(st);
2244
2245 // Print the per-region information.
2246 st->cr();
2247 print_regions_on(st);
2248 }
2249
2250 void G1CollectedHeap::print_on_error(outputStream* st) const {
2251 this->CollectedHeap::print_on_error(st);
2252
2253 if (_cm != nullptr) {
2254 st->cr();
2255 _cm->print_on_error(st);
2256 }
2257 }
2258
2259 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2260 workers()->threads_do(tc);
2261 tc->do_thread(_cm_thread);
2262 _cm->threads_do(tc);
2263 _cr->threads_do(tc);
2264 tc->do_thread(_service_thread);
2265 }
2266
2267 void G1CollectedHeap::print_tracing_info() const {
2268 rem_set()->print_summary_info();
2269 concurrent_mark()->print_summary_info();
2270 }
2271
2272 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2273 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2274 }
2275
2276 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2277
2278 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2279 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2280 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2281 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2282
2283 size_t eden_capacity_bytes =
2284 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2285
2286 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2287 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2288 survivor_used_bytes, old_gen_used_bytes, num_regions());
2289 }
2290
2291 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2292 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2293 stats->unused(), stats->used(), stats->region_end_waste(),
2294 stats->regions_filled(), stats->num_plab_filled(),
2295 stats->direct_allocated(), stats->num_direct_allocated(),
2296 stats->failure_used(), stats->failure_waste());
2297 }
2298
2299 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2300 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2301 gc_tracer->report_gc_heap_summary(when, heap_summary);
2302
2303 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2304 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2305 }
2306
2307 void G1CollectedHeap::gc_prologue(bool full) {
2308 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2309
2310 // Update common counters.
2311 increment_total_collections(full /* full gc */);
2312 if (full || collector_state()->in_concurrent_start_gc()) {
2313 increment_old_marking_cycles_started();
2314 }
2315 }
2316
2317 void G1CollectedHeap::gc_epilogue(bool full) {
2318 // Update common counters.
2319 if (full) {
2320 // Update the number of full collections that have been completed.
2321 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2322 }
2323
2324 #if COMPILER2_OR_JVMCI
2325 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2326 #endif
2327
2328 // We have just completed a GC. Update the soft reference
2329 // policy with the new heap occupancy
2330 Universe::heap()->update_capacity_and_used_at_gc();
2331
2332 _collection_pause_end = Ticks::now();
2333
2334 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2335 &_collection_set_candidates_card_set_stats);
2336 }
2337
2338 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2339 return _hrm.uncommit_inactive_regions(region_limit);
2340 }
2341
2342 bool G1CollectedHeap::has_uncommittable_regions() {
2343 return _hrm.has_inactive_regions();
2344 }
2345
2346 void G1CollectedHeap::uncommit_regions_if_necessary() {
2347 if (has_uncommittable_regions()) {
2348 G1UncommitRegionTask::enqueue();
2349 }
2350 }
2351
2352 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2353 LogTarget(Trace, gc, heap, verify) lt;
2354
2355 if (lt.is_enabled()) {
2356 LogStream ls(lt);
2357 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2358 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2359 heap_region_iterate(&cl);
2360 }
2361 }
2362
2363 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2364 uint gc_count_before,
2365 bool* succeeded,
2366 GCCause::Cause gc_cause) {
2367 assert_heap_not_locked_and_not_at_safepoint();
2368 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2369 VMThread::execute(&op);
2370
2371 HeapWord* result = op.result();
2372 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2373 assert(result == nullptr || ret_succeeded,
2374 "the result should be null if the VM did not succeed");
2375 *succeeded = ret_succeeded;
2376
2377 assert_heap_not_locked();
2378 return result;
2379 }
2380
2381 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2382 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2383
2384 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2385 if (concurrent_operation_is_full_mark) {
2386 _cm->post_concurrent_mark_start();
2387 _cm_thread->start_full_mark();
2388 } else {
2389 _cm->post_concurrent_undo_start();
2390 _cm_thread->start_undo_mark();
2391 }
2392 CGC_lock->notify();
2393 }
2394
2395 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2396 // We don't nominate objects with many remembered set entries, on
2397 // the assumption that such objects are likely still live.
2398 HeapRegionRemSet* rem_set = r->rem_set();
2399
2400 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2401 }
2402
2403 #ifndef PRODUCT
2404 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2405 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2406 public:
2407 virtual bool do_heap_region(HeapRegion* r) {
2408 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2409 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2410 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2411 "Region %u remset tracking status (%s) different to region attribute (%s)",
2412 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2413 return false;
2414 }
2415 } cl;
2416 heap_region_iterate(&cl);
2417 }
2418 #endif
2419
2420 void G1CollectedHeap::start_new_collection_set() {
2421 collection_set()->start_incremental_building();
2422
2423 clear_region_attr();
2424
2425 guarantee(_eden.length() == 0, "eden should have been cleared");
2426 policy()->transfer_survivors_to_cset(survivor());
2427
2428 // We redo the verification but now wrt to the new CSet which
2429 // has just got initialized after the previous CSet was freed.
2430 _cm->verify_no_collection_set_oops();
2431 }
2432
2433 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2434 if (collector_state()->in_concurrent_start_gc()) {
2435 return G1HeapVerifier::G1VerifyConcurrentStart;
2436 } else if (collector_state()->in_young_only_phase()) {
2437 return G1HeapVerifier::G1VerifyYoungNormal;
2438 } else {
2439 return G1HeapVerifier::G1VerifyMixed;
2440 }
2441 }
2442
2443 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2444 if (!VerifyBeforeGC) {
2445 return;
2446 }
2447 if (!G1HeapVerifier::should_verify(type)) {
2448 return;
2449 }
2450 Ticks start = Ticks::now();
2451 _verifier->prepare_for_verify();
2452 _verifier->verify_region_sets_optional();
2453 _verifier->verify_dirty_young_regions();
2454 _verifier->verify_before_gc();
2455 verify_numa_regions("GC Start");
2456 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2457 }
2458
2459 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2460 if (!VerifyAfterGC) {
2461 return;
2462 }
2463 if (!G1HeapVerifier::should_verify(type)) {
2464 return;
2465 }
2466 Ticks start = Ticks::now();
2467 _verifier->verify_after_gc();
2468 verify_numa_regions("GC End");
2469 _verifier->verify_region_sets_optional();
2470
2471 if (collector_state()->in_concurrent_start_gc()) {
2472 log_debug(gc, verify)("Marking state");
2473 _verifier->verify_marking_state();
2474 }
2475
2476 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2477 }
2478
2479 void G1CollectedHeap::expand_heap_after_young_collection(){
2480 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2481 if (expand_bytes > 0) {
2482 // No need for an ergo logging here,
2483 // expansion_amount() does this when it returns a value > 0.
2484 double expand_ms = 0.0;
2485 if (!expand(expand_bytes, _workers, &expand_ms)) {
2486 // We failed to expand the heap. Cannot do anything about it.
2487 }
2488 phase_times()->record_expand_heap_time(expand_ms);
2489 }
2490 }
2491
2492 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2493 assert_at_safepoint_on_vm_thread();
2494 guarantee(!is_gc_active(), "collection is not reentrant");
2495
2496 if (GCLocker::check_active_before_gc()) {
2497 return false;
2498 }
2499
2500 do_collection_pause_at_safepoint_helper();
2501 return true;
2502 }
2503
2504 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2505 // This summary needs to be printed before incrementing total collections.
2506 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2507 _g1h->total_collections(),
2508 true /* show_thread_times */);
2509 _g1h->print_heap_before_gc();
2510 _g1h->print_heap_regions();
2511 }
2512
2513 G1HeapPrinterMark::~G1HeapPrinterMark() {
2514 _g1h->policy()->print_age_table();
2515 _g1h->rem_set()->print_coarsen_stats();
2516 // We are at the end of the GC. Total collections has already been increased.
2517 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2518 _g1h->total_collections() - 1,
2519 false /* show_thread_times */);
2520
2521 _heap_transition.print();
2522 _g1h->print_heap_regions();
2523 _g1h->print_heap_after_gc();
2524 // Print NUMA statistics.
2525 _g1h->numa()->print_statistics();
2526 }
2527
2528 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2529 _timer(timer), _tracer(tracer) {
2530
2531 _timer->register_gc_start();
2532 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2533 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2534 }
2535
2536 G1JFRTracerMark::~G1JFRTracerMark() {
2537 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2538 _timer->register_gc_end();
2539 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2540 }
2541
2542 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2543 Ticks start = Ticks::now();
2544
2545 _survivor_evac_stats.adjust_desired_plab_size();
2546 _old_evac_stats.adjust_desired_plab_size();
2547
2548 // Start a new incremental collection set for the mutator phase.
2549 start_new_collection_set();
2550 _allocator->init_mutator_alloc_regions();
2551
2552 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2553 }
2554
2555 void G1CollectedHeap::retire_tlabs() {
2556 ensure_parsability(true);
2557 }
2558
2559 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2560 ResourceMark rm;
2561
2562 IsGCActiveMark active_gc_mark;
2563 GCIdMark gc_id_mark;
2564 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2565
2566 GCTraceCPUTime tcpu(_gc_tracer_stw);
2567
2568 _bytes_used_during_gc = 0;
2569
2570 policy()->decide_on_concurrent_start_pause();
2571 // Record whether this pause may need to trigger a concurrent operation. Later,
2572 // when we signal the G1ConcurrentMarkThread, the collector state has already
2573 // been reset for the next pause.
2574 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2575
2576 // Perform the collection.
2577 G1YoungCollector collector(gc_cause());
2578 collector.collect();
2579
2580 // It should now be safe to tell the concurrent mark thread to start
2581 // without its logging output interfering with the logging output
2582 // that came from the pause.
2583 if (should_start_concurrent_mark_operation) {
2584 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2585 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2586 // thread(s) could be running concurrently with us. Make sure that anything
2587 // after this point does not assume that we are the only GC thread running.
2588 // Note: of course, the actual marking work will not start until the safepoint
2589 // itself is released in SuspendibleThreadSet::desynchronize().
2590 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2591 ConcurrentGCBreakpoints::notify_idle_to_active();
2592 }
2593 }
2594
2595 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2596 uint num_workers = workers()->active_workers();
2597 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2598 workers()->run_task(&unlink_task);
2599 }
2600
2601 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2602 assert(obj != nullptr, "must not be null");
2603 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2604 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2605 // may falsely indicate that this is not the case here: however the collection set only
2606 // contains old regions when concurrent mark is not running.
2607 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2608 }
2609
2610 void G1CollectedHeap::make_pending_list_reachable() {
2611 if (collector_state()->in_concurrent_start_gc()) {
2612 oop pll_head = Universe::reference_pending_list();
2613 if (pll_head != nullptr) {
2614 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2615 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2616 }
2617 }
2618 }
2619
2620 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2621 _num_humongous_objects = num_humongous_total;
2622 _num_humongous_reclaim_candidates = num_humongous_candidates;
2623 }
2624
2625 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2626 const G1CollectionSetCandidates* candidates = collection_set()->candidates();
2627 return !candidates->is_empty();
2628 }
2629
2630 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2631 _collection_set_candidates_card_set_stats = stats;
2632 }
2633
2634 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2635 _young_gen_card_set_stats = stats;
2636 }
2637
2638 void G1CollectedHeap::record_obj_copy_mem_stats() {
2639 policy()->old_gen_alloc_tracker()->
2640 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2641
2642 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2643 create_g1_evac_summary(&_old_evac_stats));
2644 }
2645
2646 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2647 concurrent_mark()->clear_bitmap_for_region(hr);
2648 }
2649
2650 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2651 assert(!hr->is_free(), "the region should not be free");
2652 assert(!hr->is_empty(), "the region should not be empty");
2653 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2654
2655 // Reset region metadata to allow reuse.
2656 hr->hr_clear(true /* clear_space */);
2657 _policy->remset_tracker()->update_at_free(hr);
2658
2659 if (free_list != nullptr) {
2660 free_list->add_ordered(hr);
2661 }
2662 }
2663
2664 void G1CollectedHeap::retain_region(HeapRegion* hr) {
2665 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
2666 collection_set()->candidates()->add_retained_region_unsorted(hr);
2667 }
2668
2669 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2670 FreeRegionList* free_list) {
2671 assert(hr->is_humongous(), "this is only for humongous regions");
2672 hr->clear_humongous();
2673 free_region(hr, free_list);
2674 }
2675
2676 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2677 const uint humongous_regions_removed) {
2678 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
2679 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2680 _old_set.bulk_remove(old_regions_removed);
2681 _humongous_set.bulk_remove(humongous_regions_removed);
2682 }
2683
2684 }
2685
2686 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2687 assert(list != nullptr, "list can't be null");
2688 if (!list->is_empty()) {
2689 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2690 _hrm.insert_list_into_free_list(list);
2691 }
2692 }
2693
2694 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2695 decrease_used(bytes);
2696 }
2697
2698 void G1CollectedHeap::clear_eden() {
2699 _eden.clear();
2700 }
2701
2702 void G1CollectedHeap::clear_collection_set() {
2703 collection_set()->clear();
2704 }
2705
2706 void G1CollectedHeap::rebuild_free_region_list() {
2707 Ticks start = Ticks::now();
2708 _hrm.rebuild_free_list(workers());
2709 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2710 }
2711
2712 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2713 public:
2714 virtual bool do_heap_region(HeapRegion* r) {
2715 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2716 G1CollectedHeap::heap()->clear_region_attr(r);
2717 r->clear_young_index_in_cset();
2718 return false;
2719 }
2720 };
2721
2722 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2723 G1AbandonCollectionSetClosure cl;
2724 collection_set_iterate_all(&cl);
2725
2726 collection_set->clear();
2727 collection_set->stop_incremental_building();
2728 }
2729
2730 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2731 return _allocator->is_retained_old_region(hr);
2732 }
2733
2734 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2735 _eden.add(hr);
2736 _policy->set_region_eden(hr);
2737 }
2738
2739 #ifdef ASSERT
2740
2741 class NoYoungRegionsClosure: public HeapRegionClosure {
2742 private:
2743 bool _success;
2744 public:
2745 NoYoungRegionsClosure() : _success(true) { }
2746 bool do_heap_region(HeapRegion* r) {
2747 if (r->is_young()) {
2748 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2749 p2i(r->bottom()), p2i(r->end()));
2750 _success = false;
2751 }
2752 return false;
2753 }
2754 bool success() { return _success; }
2755 };
2756
2757 bool G1CollectedHeap::check_young_list_empty() {
2758 bool ret = (young_regions_count() == 0);
2759
2760 NoYoungRegionsClosure closure;
2761 heap_region_iterate(&closure);
2762 ret = ret && closure.success();
2763
2764 return ret;
2765 }
2766
2767 #endif // ASSERT
2768
2769 // Remove the given HeapRegion from the appropriate region set.
2770 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2771 if (hr->is_humongous()) {
2772 _humongous_set.remove(hr);
2773 } else if (hr->is_old()) {
2774 _old_set.remove(hr);
2775 } else if (hr->is_young()) {
2776 // Note that emptying the eden and survivor lists is postponed and instead
2777 // done as the first step when rebuilding the regions sets again. The reason
2778 // for this is that during a full GC string deduplication needs to know if
2779 // a collected region was young or old when the full GC was initiated.
2780 hr->uninstall_surv_rate_group();
2781 } else {
2782 // We ignore free regions, we'll empty the free list afterwards.
2783 assert(hr->is_free(), "it cannot be another type");
2784 }
2785 }
2786
2787 void G1CollectedHeap::increase_used(size_t bytes) {
2788 _summary_bytes_used += bytes;
2789 }
2790
2791 void G1CollectedHeap::decrease_used(size_t bytes) {
2792 assert(_summary_bytes_used >= bytes,
2793 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2794 _summary_bytes_used, bytes);
2795 _summary_bytes_used -= bytes;
2796 }
2797
2798 void G1CollectedHeap::set_used(size_t bytes) {
2799 _summary_bytes_used = bytes;
2800 }
2801
2802 class RebuildRegionSetsClosure : public HeapRegionClosure {
2803 private:
2804 bool _free_list_only;
2805
2806 HeapRegionSet* _old_set;
2807 HeapRegionSet* _humongous_set;
2808
2809 HeapRegionManager* _hrm;
2810
2811 size_t _total_used;
2812
2813 public:
2814 RebuildRegionSetsClosure(bool free_list_only,
2815 HeapRegionSet* old_set,
2816 HeapRegionSet* humongous_set,
2817 HeapRegionManager* hrm) :
2818 _free_list_only(free_list_only), _old_set(old_set),
2819 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2820 assert(_hrm->num_free_regions() == 0, "pre-condition");
2821 if (!free_list_only) {
2822 assert(_old_set->is_empty(), "pre-condition");
2823 assert(_humongous_set->is_empty(), "pre-condition");
2824 }
2825 }
2826
2827 bool do_heap_region(HeapRegion* r) {
2828 if (r->is_empty()) {
2829 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2830 // Add free regions to the free list
2831 r->set_free();
2832 _hrm->insert_into_free_list(r);
2833 } else if (!_free_list_only) {
2834 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2835
2836 if (r->is_humongous()) {
2837 _humongous_set->add(r);
2838 } else {
2839 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2840 // We now move all (non-humongous, non-old) regions to old gen,
2841 // and register them as such.
2842 r->move_to_old();
2843 _old_set->add(r);
2844 }
2845 _total_used += r->used();
2846 }
2847
2848 return false;
2849 }
2850
2851 size_t total_used() {
2852 return _total_used;
2853 }
2854 };
2855
2856 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2857 assert_at_safepoint_on_vm_thread();
2858
2859 if (!free_list_only) {
2860 _eden.clear();
2861 _survivor.clear();
2862 }
2863
2864 RebuildRegionSetsClosure cl(free_list_only,
2865 &_old_set, &_humongous_set,
2866 &_hrm);
2867 heap_region_iterate(&cl);
2868
2869 if (!free_list_only) {
2870 set_used(cl.total_used());
2871 }
2872 assert_used_and_recalculate_used_equal(this);
2873 }
2874
2875 // Methods for the mutator alloc region
2876
2877 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2878 bool force,
2879 uint node_index) {
2880 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2881 bool should_allocate = policy()->should_allocate_mutator_region();
2882 if (force || should_allocate) {
2883 HeapRegion* new_alloc_region = new_region(word_size,
2884 HeapRegionType::Eden,
2885 false /* do_expand */,
2886 node_index);
2887 if (new_alloc_region != nullptr) {
2888 set_region_short_lived_locked(new_alloc_region);
2889 _hr_printer.alloc(new_alloc_region, !should_allocate);
2890 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2891 return new_alloc_region;
2892 }
2893 }
2894 return nullptr;
2895 }
2896
2897 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
2898 size_t allocated_bytes) {
2899 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2900 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
2901
2902 collection_set()->add_eden_region(alloc_region);
2903 increase_used(allocated_bytes);
2904 _eden.add_used_bytes(allocated_bytes);
2905 _hr_printer.retire(alloc_region);
2906
2907 // We update the eden sizes here, when the region is retired,
2908 // instead of when it's allocated, since this is the point that its
2909 // used space has been recorded in _summary_bytes_used.
2910 monitoring_support()->update_eden_size();
2911 }
2912
2913 // Methods for the GC alloc regions
2914
2915 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
2916 if (dest.is_old()) {
2917 return true;
2918 } else {
2919 return survivor_regions_count() < policy()->max_survivor_regions();
2920 }
2921 }
2922
2923 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
2924 assert(FreeList_lock->owned_by_self(), "pre-condition");
2925
2926 if (!has_more_regions(dest)) {
2927 return nullptr;
2928 }
2929
2930 HeapRegionType type;
2931 if (dest.is_young()) {
2932 type = HeapRegionType::Survivor;
2933 } else {
2934 type = HeapRegionType::Old;
2935 }
2936
2937 HeapRegion* new_alloc_region = new_region(word_size,
2938 type,
2939 true /* do_expand */,
2940 node_index);
2941
2942 if (new_alloc_region != nullptr) {
2943 if (type.is_survivor()) {
2944 new_alloc_region->set_survivor();
2945 _survivor.add(new_alloc_region);
2946 register_new_survivor_region_with_region_attr(new_alloc_region);
2947 } else {
2948 new_alloc_region->set_old();
2949 }
2950 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2951 register_region_with_region_attr(new_alloc_region);
2952 _hr_printer.alloc(new_alloc_region);
2953 return new_alloc_region;
2954 }
2955 return nullptr;
2956 }
2957
2958 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
2959 size_t allocated_bytes,
2960 G1HeapRegionAttr dest) {
2961 _bytes_used_during_gc += allocated_bytes;
2962 if (dest.is_old()) {
2963 old_set_add(alloc_region);
2964 } else {
2965 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
2966 _survivor.add_used_bytes(allocated_bytes);
2967 }
2968
2969 bool const during_im = collector_state()->in_concurrent_start_gc();
2970 if (during_im && allocated_bytes > 0) {
2971 _cm->add_root_region(alloc_region);
2972 }
2973 _hr_printer.retire(alloc_region);
2974 }
2975
2976 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
2977 bool expanded = false;
2978 uint index = _hrm.find_highest_free(&expanded);
2979
2980 if (index != G1_NO_HRM_INDEX) {
2981 if (expanded) {
2982 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
2983 HeapRegion::GrainWords * HeapWordSize);
2984 }
2985 return _hrm.allocate_free_regions_starting_at(index, 1);
2986 }
2987 return nullptr;
2988 }
2989
2990 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
2991 assert(!_cm->is_marked_in_bitmap(obj), "must be");
2992
2993 _cm->raw_mark_in_bitmap(obj);
2994 }
2995
2996 // Optimized nmethod scanning
2997 class RegisterNMethodOopClosure: public OopClosure {
2998 G1CollectedHeap* _g1h;
2999 nmethod* _nm;
3000
3001 public:
3002 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3003 _g1h(g1h), _nm(nm) {}
3004
3005 void do_oop(oop* p) {
3006 oop heap_oop = RawAccess<>::oop_load(p);
3007 if (!CompressedOops::is_null(heap_oop)) {
3008 oop obj = CompressedOops::decode_not_null(heap_oop);
3009 HeapRegion* hr = _g1h->heap_region_containing(obj);
3010 assert(!hr->is_continues_humongous(),
3011 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3012 " starting at " HR_FORMAT,
3013 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3014
3015 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3016 hr->add_code_root_locked(_nm);
3017 }
3018 }
3019
3020 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3021 };
3022
3023 class UnregisterNMethodOopClosure: public OopClosure {
3024 G1CollectedHeap* _g1h;
3025 nmethod* _nm;
3026
3027 public:
3028 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3029 _g1h(g1h), _nm(nm) {}
3030
3031 void do_oop(oop* p) {
3032 oop heap_oop = RawAccess<>::oop_load(p);
3033 if (!CompressedOops::is_null(heap_oop)) {
3034 oop obj = CompressedOops::decode_not_null(heap_oop);
3035 HeapRegion* hr = _g1h->heap_region_containing(obj);
3036 assert(!hr->is_continues_humongous(),
3037 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3038 " starting at " HR_FORMAT,
3039 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3040
3041 hr->remove_code_root(_nm);
3042 }
3043 }
3044
3045 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3046 };
3047
3048 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3049 guarantee(nm != nullptr, "sanity");
3050 RegisterNMethodOopClosure reg_cl(this, nm);
3051 nm->oops_do(®_cl);
3052 }
3053
3054 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3055 guarantee(nm != nullptr, "sanity");
3056 UnregisterNMethodOopClosure reg_cl(this, nm);
3057 nm->oops_do(®_cl, true);
3058 }
3059
3060 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3061 if (evacuation_failed) {
3062 // Reset the G1EvacuationFailureALot counters and flags
3063 evac_failure_injector()->reset();
3064
3065 set_used(recalculate_used());
3066 } else {
3067 // The "used" of the collection set have already been subtracted
3068 // when they were freed. Add in the bytes used.
3069 increase_used(_bytes_used_during_gc);
3070 }
3071 }
3072
3073 class RebuildCodeRootClosure: public CodeBlobClosure {
3074 G1CollectedHeap* _g1h;
3075
3076 public:
3077 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3078 _g1h(g1h) {}
3079
3080 void do_code_blob(CodeBlob* cb) {
3081 nmethod* nm = cb->as_nmethod_or_null();
3082 if (nm != nullptr) {
3083 _g1h->register_nmethod(nm);
3084 }
3085 }
3086 };
3087
3088 void G1CollectedHeap::rebuild_code_roots() {
3089 RebuildCodeRootClosure blob_cl(this);
3090 CodeCache::blobs_do(&blob_cl);
3091 }
3092
3093 void G1CollectedHeap::initialize_serviceability() {
3094 _monitoring_support->initialize_serviceability();
3095 }
3096
3097 MemoryUsage G1CollectedHeap::memory_usage() {
3098 return _monitoring_support->memory_usage();
3099 }
3100
3101 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3102 return _monitoring_support->memory_managers();
3103 }
3104
3105 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3106 return _monitoring_support->memory_pools();
3107 }
3108
3109 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3110 HeapRegion* region = heap_region_containing(start);
3111 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3112 }
3113
3114 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3115 // We can reach here with an active code cache marking cycle either because the
3116 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3117 // concurrent start young collection was below the threshold) or aborted. See
3118 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3119 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3120 // still have to arm all nmethod entry barriers. They are needed for adding oop
3121 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3122 if (!CodeCache::is_gc_marking_cycle_active()) {
3123 CodeCache::on_gc_marking_cycle_start();
3124 }
3125 if (concurrent_mark_start) {
3126 CodeCache::arm_all_nmethods();
3127 }
3128 }
3129
3130 void G1CollectedHeap::finish_codecache_marking_cycle() {
3131 CodeCache::on_gc_marking_cycle_finish();
3132 CodeCache::arm_all_nmethods();
3133 }