1 /*
2 * Copyright (c) 2000, 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/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "compiler/oopMap.hpp"
33 #include "gc/serial/cardTableRS.hpp"
34 #include "gc/serial/defNewGeneration.hpp"
35 #include "gc/serial/genMarkSweep.hpp"
36 #include "gc/serial/markSweep.hpp"
37 #include "gc/shared/adaptiveSizePolicy.hpp"
38 #include "gc/shared/cardTableBarrierSet.hpp"
39 #include "gc/shared/classUnloadingContext.hpp"
40 #include "gc/shared/collectedHeap.inline.hpp"
41 #include "gc/shared/collectorCounters.hpp"
42 #include "gc/shared/continuationGCSupport.inline.hpp"
43 #include "gc/shared/gcId.hpp"
44 #include "gc/shared/gcInitLogger.hpp"
45 #include "gc/shared/gcLocker.hpp"
46 #include "gc/shared/gcPolicyCounters.hpp"
47 #include "gc/shared/gcTrace.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "gc/shared/gcVMOperations.hpp"
50 #include "gc/shared/genArguments.hpp"
51 #include "gc/shared/genCollectedHeap.hpp"
52 #include "gc/shared/generationSpec.hpp"
53 #include "gc/shared/locationPrinter.inline.hpp"
54 #include "gc/shared/oopStorage.inline.hpp"
55 #include "gc/shared/oopStorageParState.inline.hpp"
56 #include "gc/shared/oopStorageSet.inline.hpp"
57 #include "gc/shared/scavengableNMethods.hpp"
58 #include "gc/shared/space.hpp"
59 #include "gc/shared/strongRootsScope.hpp"
60 #include "gc/shared/weakProcessor.hpp"
61 #include "gc/shared/workerThread.hpp"
62 #include "memory/iterator.hpp"
63 #include "memory/metaspaceCounters.hpp"
64 #include "memory/metaspaceUtils.hpp"
65 #include "memory/resourceArea.hpp"
66 #include "memory/universe.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/handles.hpp"
69 #include "runtime/handles.inline.hpp"
70 #include "runtime/java.hpp"
71 #include "runtime/threads.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "services/memoryService.hpp"
74 #include "utilities/autoRestore.hpp"
75 #include "utilities/debug.hpp"
76 #include "utilities/formatBuffer.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/stack.inline.hpp"
79 #include "utilities/vmError.hpp"
80 #if INCLUDE_JVMCI
81 #include "jvmci/jvmci.hpp"
82 #endif
83
84 GenCollectedHeap::GenCollectedHeap(Generation::Name young,
85 Generation::Name old,
86 const char* policy_counters_name) :
87 CollectedHeap(),
88 _young_gen(nullptr),
89 _old_gen(nullptr),
90 _young_gen_spec(new GenerationSpec(young,
91 NewSize,
92 MaxNewSize,
93 GenAlignment)),
94 _old_gen_spec(new GenerationSpec(old,
95 OldSize,
96 MaxOldSize,
97 GenAlignment)),
98 _rem_set(nullptr),
99 _soft_ref_gen_policy(),
100 _size_policy(nullptr),
101 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
102 _incremental_collection_failed(false),
103 _full_collections_completed(0),
104 _young_manager(nullptr),
105 _old_manager(nullptr) {
106 }
107
108 jint GenCollectedHeap::initialize() {
109 // Allocate space for the heap.
110
111 ReservedHeapSpace heap_rs = allocate(HeapAlignment);
112
113 if (!heap_rs.is_reserved()) {
114 vm_shutdown_during_initialization(
115 "Could not reserve enough space for object heap");
116 return JNI_ENOMEM;
117 }
118
119 initialize_reserved_region(heap_rs);
120
121 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size());
122 ReservedSpace old_rs = heap_rs.last_part(_young_gen_spec->max_size());
123
124 _rem_set = create_rem_set(heap_rs.region());
125 _rem_set->initialize(young_rs.base(), old_rs.base());
126
127 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
128 bs->initialize();
129 BarrierSet::set_barrier_set(bs);
130
131 _young_gen = _young_gen_spec->init(young_rs, rem_set());
132 _old_gen = _old_gen_spec->init(old_rs, rem_set());
133
134 GCInitLogger::print();
135
136 return JNI_OK;
137 }
138
139 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
140 return new CardTableRS(reserved_region);
141 }
142
143 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
144 size_t init_promo_size,
145 size_t init_survivor_size) {
146 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
147 _size_policy = new AdaptiveSizePolicy(init_eden_size,
148 init_promo_size,
149 init_survivor_size,
150 max_gc_pause_sec,
151 GCTimeRatio);
152 }
153
154 ReservedHeapSpace GenCollectedHeap::allocate(size_t alignment) {
155 // Now figure out the total size.
156 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
157 assert(alignment % pageSize == 0, "Must be");
158
159 // Check for overflow.
160 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
161 if (total_reserved < _young_gen_spec->max_size()) {
162 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
163 "the maximum representable size");
164 }
165 assert(total_reserved % alignment == 0,
166 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
167 SIZE_FORMAT, total_reserved, alignment);
168
169 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
170 size_t used_page_size = heap_rs.page_size();
171
172 os::trace_page_sizes("Heap",
173 MinHeapSize,
174 total_reserved,
175 used_page_size,
176 heap_rs.base(),
177 heap_rs.size());
178
179 return heap_rs;
180 }
181
182 class GenIsScavengable : public BoolObjectClosure {
183 public:
184 bool do_object_b(oop obj) {
185 return GenCollectedHeap::heap()->is_in_young(obj);
186 }
187 };
188
189 static GenIsScavengable _is_scavengable;
190
191 void GenCollectedHeap::post_initialize() {
192 CollectedHeap::post_initialize();
193
194 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
195
196 def_new_gen->ref_processor_init();
197
198 initialize_size_policy(def_new_gen->eden()->capacity(),
199 _old_gen->capacity(),
200 def_new_gen->from()->capacity());
201
202 MarkSweep::initialize();
203
204 ScavengableNMethods::initialize(&_is_scavengable);
205 }
206
207 PreGenGCValues GenCollectedHeap::get_pre_gc_values() const {
208 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
209
210 return PreGenGCValues(def_new_gen->used(),
211 def_new_gen->capacity(),
212 def_new_gen->eden()->used(),
213 def_new_gen->eden()->capacity(),
214 def_new_gen->from()->used(),
215 def_new_gen->from()->capacity(),
216 old_gen()->used(),
217 old_gen()->capacity());
218 }
219
220 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
221 return _young_gen_spec;
222 }
223
224 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
225 return _old_gen_spec;
226 }
227
228 size_t GenCollectedHeap::capacity() const {
229 return _young_gen->capacity() + _old_gen->capacity();
230 }
231
232 size_t GenCollectedHeap::used() const {
233 return _young_gen->used() + _old_gen->used();
234 }
235
236 void GenCollectedHeap::save_used_regions() {
237 _old_gen->save_used_region();
238 _young_gen->save_used_region();
239 }
240
241 size_t GenCollectedHeap::max_capacity() const {
242 return _young_gen->max_capacity() + _old_gen->max_capacity();
243 }
244
245 // Update the _full_collections_completed counter
246 // at the end of a stop-world full GC.
247 unsigned int GenCollectedHeap::update_full_collections_completed() {
248 assert(_full_collections_completed <= _total_full_collections,
249 "Can't complete more collections than were started");
250 _full_collections_completed = _total_full_collections;
251 return _full_collections_completed;
252 }
253
254 // Return true if any of the following is true:
255 // . the allocation won't fit into the current young gen heap
256 // . gc locker is occupied (jni critical section)
257 // . heap memory is tight -- the most recent previous collection
258 // was a full collection because a partial collection (would
259 // have) failed and is likely to fail again
260 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
261 size_t young_capacity = _young_gen->capacity_before_gc();
262 return (word_size > heap_word_size(young_capacity))
263 || GCLocker::is_active_and_needs_gc()
264 || incremental_collection_failed();
265 }
266
267 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
268 HeapWord* result = nullptr;
269 if (_old_gen->should_allocate(size, is_tlab)) {
270 result = _old_gen->expand_and_allocate(size, is_tlab);
271 }
272 if (result == nullptr) {
273 if (_young_gen->should_allocate(size, is_tlab)) {
274 result = _young_gen->expand_and_allocate(size, is_tlab);
275 }
276 }
277 assert(result == nullptr || is_in_reserved(result), "result not in heap");
278 return result;
279 }
280
281 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
282 bool is_tlab) {
283
284 HeapWord* result = nullptr;
285
286 // Loop until the allocation is satisfied, or unsatisfied after GC.
287 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
288
289 // First allocation attempt is lock-free.
290 Generation *young = _young_gen;
291 if (young->should_allocate(size, is_tlab)) {
292 result = young->par_allocate(size, is_tlab);
293 if (result != nullptr) {
294 assert(is_in_reserved(result), "result not in heap");
295 return result;
296 }
297 }
298 uint gc_count_before; // Read inside the Heap_lock locked region.
299 {
300 MutexLocker ml(Heap_lock);
301 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
302 // Note that only large objects get a shot at being
303 // allocated in later generations.
304 bool first_only = !should_try_older_generation_allocation(size);
305
306 result = attempt_allocation(size, is_tlab, first_only);
307 if (result != nullptr) {
308 assert(is_in_reserved(result), "result not in heap");
309 return result;
310 }
311
312 if (GCLocker::is_active_and_needs_gc()) {
313 if (is_tlab) {
314 return nullptr; // Caller will retry allocating individual object.
315 }
316 if (!is_maximal_no_gc()) {
317 // Try and expand heap to satisfy request.
318 result = expand_heap_and_allocate(size, is_tlab);
319 // Result could be null if we are out of space.
320 if (result != nullptr) {
321 return result;
322 }
323 }
324
325 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
326 return nullptr; // We didn't get to do a GC and we didn't get any memory.
327 }
328
329 // If this thread is not in a jni critical section, we stall
330 // the requestor until the critical section has cleared and
331 // GC allowed. When the critical section clears, a GC is
332 // initiated by the last thread exiting the critical section; so
333 // we retry the allocation sequence from the beginning of the loop,
334 // rather than causing more, now probably unnecessary, GC attempts.
335 JavaThread* jthr = JavaThread::current();
336 if (!jthr->in_critical()) {
337 MutexUnlocker mul(Heap_lock);
338 // Wait for JNI critical section to be exited
339 GCLocker::stall_until_clear();
340 gclocker_stalled_count += 1;
341 continue;
342 } else {
343 if (CheckJNICalls) {
344 fatal("Possible deadlock due to allocating while"
345 " in jni critical section");
346 }
347 return nullptr;
348 }
349 }
350
351 // Read the gc count while the heap lock is held.
352 gc_count_before = total_collections();
353 }
354
355 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
356 VMThread::execute(&op);
357 if (op.prologue_succeeded()) {
358 result = op.result();
359 if (op.gc_locked()) {
360 assert(result == nullptr, "must be null if gc_locked() is true");
361 continue; // Retry and/or stall as necessary.
362 }
363
364 assert(result == nullptr || is_in_reserved(result),
365 "result not in heap");
366 return result;
367 }
368
369 // Give a warning if we seem to be looping forever.
370 if ((QueuedAllocationWarningCount > 0) &&
371 (try_count % QueuedAllocationWarningCount == 0)) {
372 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
373 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
374 }
375 }
376 }
377
378 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
379 bool is_tlab,
380 bool first_only) {
381 HeapWord* res = nullptr;
382
383 if (_young_gen->should_allocate(size, is_tlab)) {
384 res = _young_gen->allocate(size, is_tlab);
385 if (res != nullptr || first_only) {
386 return res;
387 }
388 }
389
390 if (_old_gen->should_allocate(size, is_tlab)) {
391 res = _old_gen->allocate(size, is_tlab);
392 }
393
394 return res;
395 }
396
397 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
398 bool* gc_overhead_limit_was_exceeded) {
399 return mem_allocate_work(size,
400 false /* is_tlab */);
401 }
402
403 bool GenCollectedHeap::must_clear_all_soft_refs() {
404 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
405 _gc_cause == GCCause::_wb_full_gc;
406 }
407
408 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
409 bool is_tlab, bool run_verification, bool clear_soft_refs) {
410 FormatBuffer<> title("Collect gen: %s", gen->short_name());
411 GCTraceTime(Trace, gc, phases) t1(title);
412 TraceCollectorStats tcs(gen->counters());
413 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause(), heap()->is_young_gen(gen) ? "end of minor GC" : "end of major GC");
414
415 gen->stat_record()->invocations++;
416 gen->stat_record()->accumulated_time.start();
417
418 // Must be done anew before each collection because
419 // a previous collection will do mangling and will
420 // change top of some spaces.
421 record_gen_tops_before_GC();
422
423 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
424
425 if (run_verification && VerifyBeforeGC) {
426 Universe::verify("Before GC");
427 }
428 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
429
430 // Do collection work
431 {
432 save_marks(); // save marks for all gens
433
434 gen->collect(full, clear_soft_refs, size, is_tlab);
435 }
436
437 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
438
439 gen->stat_record()->accumulated_time.stop();
440
441 update_gc_stats(gen, full);
442
443 if (run_verification && VerifyAfterGC) {
444 Universe::verify("After GC");
445 }
446 }
447
448 void GenCollectedHeap::do_collection(bool full,
449 bool clear_all_soft_refs,
450 size_t size,
451 bool is_tlab,
452 GenerationType max_generation) {
453 ResourceMark rm;
454 DEBUG_ONLY(Thread* my_thread = Thread::current();)
455
456 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
457 assert(my_thread->is_VM_thread(), "only VM thread");
458 assert(Heap_lock->is_locked(),
459 "the requesting thread should have the Heap_lock");
460 guarantee(!is_stw_gc_active(), "collection is not reentrant");
461
462 if (GCLocker::check_active_before_gc()) {
463 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
464 }
465
466 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
467 soft_ref_policy()->should_clear_all_soft_refs();
468
469 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
470
471 AutoModifyRestore<bool> temporarily(_is_stw_gc_active, true);
472
473 bool complete = full && (max_generation == OldGen);
474 bool old_collects_young = complete && !ScavengeBeforeFullGC;
475 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
476
477 const PreGenGCValues pre_gc_values = get_pre_gc_values();
478
479 bool run_verification = total_collections() >= VerifyGCStartAt;
480 bool prepared_for_verification = false;
481 bool do_full_collection = false;
482
483 if (do_young_collection) {
484 GCIdMark gc_id_mark;
485 GCTraceCPUTime tcpu(((DefNewGeneration*)_young_gen)->gc_tracer());
486 GCTraceTime(Info, gc) t("Pause Young", nullptr, gc_cause(), true);
487
488 print_heap_before_gc();
489
490 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
491 prepare_for_verify();
492 prepared_for_verification = true;
493 }
494
495 gc_prologue(complete);
496 increment_total_collections(complete);
497
498 collect_generation(_young_gen,
499 full,
500 size,
501 is_tlab,
502 run_verification && VerifyGCLevel <= 0,
503 do_clear_all_soft_refs);
504
505 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
506 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
507 // Allocation request was met by young GC.
508 size = 0;
509 }
510
511 // Ask if young collection is enough. If so, do the final steps for young collection,
512 // and fallthrough to the end.
513 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
514 if (!do_full_collection) {
515 // Adjust generation sizes.
516 _young_gen->compute_new_size();
517
518 print_heap_change(pre_gc_values);
519
520 // Track memory usage and detect low memory after GC finishes
521 MemoryService::track_memory_usage();
522
523 gc_epilogue(complete);
524 }
525
526 print_heap_after_gc();
527
528 } else {
529 // No young collection, ask if we need to perform Full collection.
530 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
531 }
532
533 if (do_full_collection) {
534 GCIdMark gc_id_mark;
535 GCTraceCPUTime tcpu(GenMarkSweep::gc_tracer());
536 GCTraceTime(Info, gc) t("Pause Full", nullptr, gc_cause(), true);
537
538 print_heap_before_gc();
539
540 if (!prepared_for_verification && run_verification &&
541 VerifyGCLevel <= 1 && VerifyBeforeGC) {
542 prepare_for_verify();
543 }
544
545 if (!do_young_collection) {
546 gc_prologue(complete);
547 increment_total_collections(complete);
548 }
549
550 // Accounting quirk: total full collections would be incremented when "complete"
551 // is set, by calling increment_total_collections above. However, we also need to
552 // account Full collections that had "complete" unset.
553 if (!complete) {
554 increment_total_full_collections();
555 }
556
557 CodeCache::on_gc_marking_cycle_start();
558
559 ClassUnloadingContext ctx(1 /* num_nmethod_unlink_workers */,
560 false /* unregister_nmethods_during_purge */,
561 false /* lock_codeblob_free_separately */);
562
563 collect_generation(_old_gen,
564 full,
565 size,
566 is_tlab,
567 run_verification && VerifyGCLevel <= 1,
568 do_clear_all_soft_refs);
569
570 CodeCache::on_gc_marking_cycle_finish();
571 CodeCache::arm_all_nmethods();
572
573 // Adjust generation sizes.
574 _old_gen->compute_new_size();
575 _young_gen->compute_new_size();
576
577 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
578 ClassLoaderDataGraph::purge(true /* at_safepoint */);
579 DEBUG_ONLY(MetaspaceUtils::verify();)
580
581 // Need to clear claim bits for the next mark.
582 ClassLoaderDataGraph::clear_claimed_marks();
583
584 // Resize the metaspace capacity after full collections
585 MetaspaceGC::compute_new_size();
586 update_full_collections_completed();
587
588 print_heap_change(pre_gc_values);
589
590 // Track memory usage and detect low memory after GC finishes
591 MemoryService::track_memory_usage();
592
593 // Need to tell the epilogue code we are done with Full GC, regardless what was
594 // the initial value for "complete" flag.
595 gc_epilogue(true);
596
597 print_heap_after_gc();
598 }
599 }
600
601 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
602 GenCollectedHeap::GenerationType max_gen) const {
603 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
604 }
605
606 void GenCollectedHeap::register_nmethod(nmethod* nm) {
607 ScavengableNMethods::register_nmethod(nm);
608 }
609
610 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
611 ScavengableNMethods::unregister_nmethod(nm);
612 }
613
614 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
615 ScavengableNMethods::verify_nmethod(nm);
616 }
617
618 void GenCollectedHeap::prune_scavengable_nmethods() {
619 ScavengableNMethods::prune_nmethods_not_into_young();
620 }
621
622 void GenCollectedHeap::prune_unlinked_nmethods() {
623 ScavengableNMethods::prune_unlinked_nmethods();
624 }
625
626 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
627 GCCauseSetter x(this, GCCause::_allocation_failure);
628 HeapWord* result = nullptr;
629
630 assert(size != 0, "Precondition violated");
631 if (GCLocker::is_active_and_needs_gc()) {
632 // GC locker is active; instead of a collection we will attempt
633 // to expand the heap, if there's room for expansion.
634 if (!is_maximal_no_gc()) {
635 result = expand_heap_and_allocate(size, is_tlab);
636 }
637 return result; // Could be null if we are out of space.
638 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
639 // Do an incremental collection.
640 do_collection(false, // full
641 false, // clear_all_soft_refs
642 size, // size
643 is_tlab, // is_tlab
644 GenCollectedHeap::OldGen); // max_generation
645 } else {
646 log_trace(gc)(" :: Trying full because partial may fail :: ");
647 // Try a full collection; see delta for bug id 6266275
648 // for the original code and why this has been simplified
649 // with from-space allocation criteria modified and
650 // such allocation moved out of the safepoint path.
651 do_collection(true, // full
652 false, // clear_all_soft_refs
653 size, // size
654 is_tlab, // is_tlab
655 GenCollectedHeap::OldGen); // max_generation
656 }
657
658 result = attempt_allocation(size, is_tlab, false /*first_only*/);
659
660 if (result != nullptr) {
661 assert(is_in_reserved(result), "result not in heap");
662 return result;
663 }
664
665 // OK, collection failed, try expansion.
666 result = expand_heap_and_allocate(size, is_tlab);
667 if (result != nullptr) {
668 return result;
669 }
670
671 // If we reach this point, we're really out of memory. Try every trick
672 // we can to reclaim memory. Force collection of soft references. Force
673 // a complete compaction of the heap. Any additional methods for finding
674 // free memory should be here, especially if they are expensive. If this
675 // attempt fails, an OOM exception will be thrown.
676 {
677 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
678
679 do_collection(true, // full
680 true, // clear_all_soft_refs
681 size, // size
682 is_tlab, // is_tlab
683 GenCollectedHeap::OldGen); // max_generation
684 }
685
686 result = attempt_allocation(size, is_tlab, false /* first_only */);
687 if (result != nullptr) {
688 assert(is_in_reserved(result), "result not in heap");
689 return result;
690 }
691
692 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
693 "Flag should have been handled and cleared prior to this point");
694
695 // What else? We might try synchronous finalization later. If the total
696 // space available is large enough for the allocation, then a more
697 // complete compaction phase than we've tried so far might be
698 // appropriate.
699 return nullptr;
700 }
701
702 #ifdef ASSERT
703 class AssertNonScavengableClosure: public OopClosure {
704 public:
705 virtual void do_oop(oop* p) {
706 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
707 "Referent should not be scavengable."); }
708 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
709 };
710 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
711 #endif
712
713 void GenCollectedHeap::process_roots(ScanningOption so,
714 OopClosure* strong_roots,
715 CLDClosure* strong_cld_closure,
716 CLDClosure* weak_cld_closure,
717 CodeBlobToOopClosure* code_roots) {
718 // General roots.
719 assert(code_roots != nullptr, "code root closure should always be set");
720
721 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
722
723 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
724 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? nullptr : code_roots;
725
726 Threads::oops_do(strong_roots, roots_from_code_p);
727
728 OopStorageSet::strong_oops_do(strong_roots);
729
730 if (so & SO_ScavengeCodeCache) {
731 assert(code_roots != nullptr, "must supply closure for code cache");
732
733 // We only visit parts of the CodeCache when scavenging.
734 ScavengableNMethods::nmethods_do(code_roots);
735 }
736 if (so & SO_AllCodeCache) {
737 assert(code_roots != nullptr, "must supply closure for code cache");
738
739 // CMSCollector uses this to do intermediate-strength collections.
740 // We scan the entire code cache, since CodeCache::do_unloading is not called.
741 CodeCache::blobs_do(code_roots);
742 }
743 // Verify that the code cache contents are not subject to
744 // movement by a scavenging collection.
745 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
746 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
747 }
748
749 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
750 WeakProcessor::oops_do(root_closure);
751 }
752
753 bool GenCollectedHeap::no_allocs_since_save_marks() {
754 return _young_gen->no_allocs_since_save_marks() &&
755 _old_gen->no_allocs_since_save_marks();
756 }
757
758 // public collection interfaces
759 void GenCollectedHeap::collect(GCCause::Cause cause) {
760 // The caller doesn't have the Heap_lock
761 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
762
763 unsigned int gc_count_before;
764 unsigned int full_gc_count_before;
765
766 {
767 MutexLocker ml(Heap_lock);
768 // Read the GC count while holding the Heap_lock
769 gc_count_before = total_collections();
770 full_gc_count_before = total_full_collections();
771 }
772
773 if (GCLocker::should_discard(cause, gc_count_before)) {
774 return;
775 }
776
777 bool should_run_young_gc = (cause == GCCause::_wb_young_gc)
778 || (cause == GCCause::_gc_locker)
779 DEBUG_ONLY(|| (cause == GCCause::_scavenge_alot));
780
781 const GenerationType max_generation = should_run_young_gc
782 ? YoungGen
783 : OldGen;
784
785 while (true) {
786 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
787 cause, max_generation);
788 VMThread::execute(&op);
789
790 if (!GCCause::is_explicit_full_gc(cause)) {
791 return;
792 }
793
794 {
795 MutexLocker ml(Heap_lock);
796 // Read the GC count while holding the Heap_lock
797 if (full_gc_count_before != total_full_collections()) {
798 return;
799 }
800 }
801
802 if (GCLocker::is_active_and_needs_gc()) {
803 // If GCLocker is active, wait until clear before retrying.
804 GCLocker::stall_until_clear();
805 }
806 }
807 }
808
809 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
810 do_full_collection(clear_all_soft_refs, OldGen);
811 }
812
813 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
814 GenerationType last_generation) {
815 do_collection(true, // full
816 clear_all_soft_refs, // clear_all_soft_refs
817 0, // size
818 false, // is_tlab
819 last_generation); // last_generation
820 // Hack XXX FIX ME !!!
821 // A scavenge may not have been attempted, or may have
822 // been attempted and failed, because the old gen was too full
823 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
824 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
825 // This time allow the old gen to be collected as well
826 do_collection(true, // full
827 clear_all_soft_refs, // clear_all_soft_refs
828 0, // size
829 false, // is_tlab
830 OldGen); // last_generation
831 }
832 }
833
834 bool GenCollectedHeap::is_in_young(const void* p) const {
835 bool result = p < _old_gen->reserved().start();
836 assert(result == _young_gen->is_in_reserved(p),
837 "incorrect test - result=%d, p=" PTR_FORMAT, result, p2i(p));
838 return result;
839 }
840
841 bool GenCollectedHeap::requires_barriers(stackChunkOop obj) const {
842 return !is_in_young(obj);
843 }
844
845 // Returns "TRUE" iff "p" points into the committed areas of the heap.
846 bool GenCollectedHeap::is_in(const void* p) const {
847 return _young_gen->is_in(p) || _old_gen->is_in(p);
848 }
849
850 #ifdef ASSERT
851 // Don't implement this by using is_in_young(). This method is used
852 // in some cases to check that is_in_young() is correct.
853 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
854 assert(is_in_reserved(p) || p == nullptr,
855 "Does not work if address is non-null and outside of the heap");
856 return p < _young_gen->reserved().end() && p != nullptr;
857 }
858 #endif
859
860 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
861 _young_gen->oop_iterate(cl);
862 _old_gen->oop_iterate(cl);
863 }
864
865 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
866 _young_gen->object_iterate(cl);
867 _old_gen->object_iterate(cl);
868 }
869
870 Space* GenCollectedHeap::space_containing(const void* addr) const {
871 Space* res = _young_gen->space_containing(addr);
872 if (res != nullptr) {
873 return res;
874 }
875 res = _old_gen->space_containing(addr);
876 assert(res != nullptr, "Could not find containing space");
877 return res;
878 }
879
880 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
881 assert(is_in_reserved(addr), "block_start of address outside of heap");
882 if (_young_gen->is_in_reserved(addr)) {
883 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
884 return _young_gen->block_start(addr);
885 }
886
887 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
888 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
889 return _old_gen->block_start(addr);
890 }
891
892 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
893 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
894 assert(block_start(addr) == addr, "addr must be a block start");
895 if (_young_gen->is_in_reserved(addr)) {
896 return _young_gen->block_is_obj(addr);
897 }
898
899 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
900 return _old_gen->block_is_obj(addr);
901 }
902
903 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
904 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
905 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
906 return _young_gen->tlab_capacity();
907 }
908
909 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
910 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
911 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
912 return _young_gen->tlab_used();
913 }
914
915 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
916 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
917 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
918 return _young_gen->unsafe_max_tlab_alloc();
919 }
920
921 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
922 size_t requested_size,
923 size_t* actual_size) {
924 HeapWord* result = mem_allocate_work(requested_size /* size */,
925 true /* is_tlab */);
926 if (result != nullptr) {
927 *actual_size = requested_size;
928 }
929
930 return result;
931 }
932
933 // Requires "*prev_ptr" to be non-null. Deletes and a block of minimal size
934 // from the list headed by "*prev_ptr".
935 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
936 bool first = true;
937 size_t min_size = 0; // "first" makes this conceptually infinite.
938 ScratchBlock **smallest_ptr, *smallest;
939 ScratchBlock *cur = *prev_ptr;
940 while (cur) {
941 assert(*prev_ptr == cur, "just checking");
942 if (first || cur->num_words < min_size) {
943 smallest_ptr = prev_ptr;
944 smallest = cur;
945 min_size = smallest->num_words;
946 first = false;
947 }
948 prev_ptr = &cur->next;
949 cur = cur->next;
950 }
951 smallest = *smallest_ptr;
952 *smallest_ptr = smallest->next;
953 return smallest;
954 }
955
956 // Sort the scratch block list headed by res into decreasing size order,
957 // and set "res" to the result.
958 static void sort_scratch_list(ScratchBlock*& list) {
959 ScratchBlock* sorted = nullptr;
960 ScratchBlock* unsorted = list;
961 while (unsorted) {
962 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
963 smallest->next = sorted;
964 sorted = smallest;
965 }
966 list = sorted;
967 }
968
969 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
970 size_t max_alloc_words) {
971 ScratchBlock* res = nullptr;
972 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
973 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
974 sort_scratch_list(res);
975 return res;
976 }
977
978 void GenCollectedHeap::release_scratch() {
979 _young_gen->reset_scratch();
980 _old_gen->reset_scratch();
981 }
982
983 void GenCollectedHeap::prepare_for_verify() {
984 ensure_parsability(false); // no need to retire TLABs
985 }
986
987 void GenCollectedHeap::generation_iterate(GenClosure* cl,
988 bool old_to_young) {
989 if (old_to_young) {
990 cl->do_generation(_old_gen);
991 cl->do_generation(_young_gen);
992 } else {
993 cl->do_generation(_young_gen);
994 cl->do_generation(_old_gen);
995 }
996 }
997
998 bool GenCollectedHeap::is_maximal_no_gc() const {
999 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1000 }
1001
1002 void GenCollectedHeap::save_marks() {
1003 _young_gen->save_marks();
1004 _old_gen->save_marks();
1005 }
1006
1007 GenCollectedHeap* GenCollectedHeap::heap() {
1008 // SerialHeap is the only subtype of GenCollectedHeap.
1009 return named_heap<GenCollectedHeap>(CollectedHeap::Serial);
1010 }
1011
1012 #if INCLUDE_SERIALGC
1013 void GenCollectedHeap::prepare_for_compaction() {
1014 // Start by compacting into same gen.
1015 CompactPoint cp(_old_gen);
1016 _old_gen->prepare_for_compaction(&cp);
1017 _young_gen->prepare_for_compaction(&cp);
1018 }
1019 #endif // INCLUDE_SERIALGC
1020
1021 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1022 log_debug(gc, verify)("%s", _old_gen->name());
1023 _old_gen->verify();
1024
1025 log_debug(gc, verify)("%s", _young_gen->name());
1026 _young_gen->verify();
1027
1028 log_debug(gc, verify)("RemSet");
1029 rem_set()->verify();
1030 }
1031
1032 void GenCollectedHeap::print_on(outputStream* st) const {
1033 if (_young_gen != nullptr) {
1034 _young_gen->print_on(st);
1035 }
1036 if (_old_gen != nullptr) {
1037 _old_gen->print_on(st);
1038 }
1039 MetaspaceUtils::print_on(st);
1040 }
1041
1042 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1043 }
1044
1045 bool GenCollectedHeap::print_location(outputStream* st, void* addr) const {
1046 return BlockLocationPrinter<GenCollectedHeap>::print_location(st, addr);
1047 }
1048
1049 void GenCollectedHeap::print_tracing_info() const {
1050 if (log_is_enabled(Debug, gc, heap, exit)) {
1051 LogStreamHandle(Debug, gc, heap, exit) lsh;
1052 _young_gen->print_summary_info_on(&lsh);
1053 _old_gen->print_summary_info_on(&lsh);
1054 }
1055 }
1056
1057 void GenCollectedHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
1058 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
1059
1060 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
1061 HEAP_CHANGE_FORMAT" "
1062 HEAP_CHANGE_FORMAT,
1063 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
1064 pre_gc_values.young_gen_used(),
1065 pre_gc_values.young_gen_capacity(),
1066 def_new_gen->used(),
1067 def_new_gen->capacity()),
1068 HEAP_CHANGE_FORMAT_ARGS("Eden",
1069 pre_gc_values.eden_used(),
1070 pre_gc_values.eden_capacity(),
1071 def_new_gen->eden()->used(),
1072 def_new_gen->eden()->capacity()),
1073 HEAP_CHANGE_FORMAT_ARGS("From",
1074 pre_gc_values.from_used(),
1075 pre_gc_values.from_capacity(),
1076 def_new_gen->from()->used(),
1077 def_new_gen->from()->capacity()));
1078 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
1079 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
1080 pre_gc_values.old_gen_used(),
1081 pre_gc_values.old_gen_capacity(),
1082 old_gen()->used(),
1083 old_gen()->capacity()));
1084 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1085 }
1086
1087 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1088 private:
1089 bool _full;
1090 public:
1091 void do_generation(Generation* gen) {
1092 gen->gc_prologue(_full);
1093 }
1094 GenGCPrologueClosure(bool full) : _full(full) {};
1095 };
1096
1097 void GenCollectedHeap::gc_prologue(bool full) {
1098 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1099
1100 // Fill TLAB's and such
1101 ensure_parsability(true); // retire TLABs
1102
1103 // Walk generations
1104 GenGCPrologueClosure blk(full);
1105 generation_iterate(&blk, false); // not old-to-young.
1106 };
1107
1108 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1109 private:
1110 bool _full;
1111 public:
1112 void do_generation(Generation* gen) {
1113 gen->gc_epilogue(_full);
1114 }
1115 GenGCEpilogueClosure(bool full) : _full(full) {};
1116 };
1117
1118 void GenCollectedHeap::gc_epilogue(bool full) {
1119 #if COMPILER2_OR_JVMCI
1120 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1121 #endif // COMPILER2_OR_JVMCI
1122
1123 resize_all_tlabs();
1124
1125 GenGCEpilogueClosure blk(full);
1126 generation_iterate(&blk, false); // not old-to-young.
1127
1128 MetaspaceCounters::update_performance_counters();
1129 };
1130
1131 #ifndef PRODUCT
1132 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1133 private:
1134 public:
1135 void do_generation(Generation* gen) {
1136 gen->record_spaces_top();
1137 }
1138 };
1139
1140 void GenCollectedHeap::record_gen_tops_before_GC() {
1141 if (ZapUnusedHeapArea) {
1142 GenGCSaveTopsBeforeGCClosure blk;
1143 generation_iterate(&blk, false); // not old-to-young.
1144 }
1145 }
1146 #endif // not PRODUCT
1147
1148 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1149 public:
1150 void do_generation(Generation* gen) {
1151 gen->ensure_parsability();
1152 }
1153 };
1154
1155 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1156 CollectedHeap::ensure_parsability(retire_tlabs);
1157 GenEnsureParsabilityClosure ep_cl;
1158 generation_iterate(&ep_cl, false);
1159 }