1 /*
2 * Copyright (c) 2017, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "compiler/oopMap.hpp"
32 #include "gc/serial/cardTableRS.hpp"
33 #include "gc/serial/defNewGeneration.inline.hpp"
34 #include "gc/serial/serialFullGC.hpp"
35 #include "gc/serial/serialHeap.inline.hpp"
36 #include "gc/serial/serialMemoryPools.hpp"
37 #include "gc/serial/serialVMOperations.hpp"
38 #include "gc/serial/tenuredGeneration.inline.hpp"
39 #include "gc/shared/cardTableBarrierSet.hpp"
40 #include "gc/shared/classUnloadingContext.hpp"
41 #include "gc/shared/collectedHeap.inline.hpp"
42 #include "gc/shared/collectorCounters.hpp"
43 #include "gc/shared/continuationGCSupport.inline.hpp"
44 #include "gc/shared/gcId.hpp"
45 #include "gc/shared/gcInitLogger.hpp"
46 #include "gc/shared/gcLocker.inline.hpp"
47 #include "gc/shared/gcPolicyCounters.hpp"
48 #include "gc/shared/gcTrace.hpp"
49 #include "gc/shared/gcTraceTime.inline.hpp"
50 #include "gc/shared/gcVMOperations.hpp"
51 #include "gc/shared/genArguments.hpp"
52 #include "gc/shared/isGCActiveMark.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/suspendibleThreadSet.hpp"
61 #include "gc/shared/weakProcessor.hpp"
62 #include "gc/shared/workerThread.hpp"
63 #include "memory/iterator.hpp"
64 #include "memory/metaspaceCounters.hpp"
65 #include "memory/metaspaceUtils.hpp"
66 #include "memory/resourceArea.hpp"
67 #include "memory/universe.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/handles.hpp"
70 #include "runtime/handles.inline.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/mutexLocker.hpp"
73 #include "runtime/threads.hpp"
74 #include "runtime/vmThread.hpp"
75 #include "services/memoryManager.hpp"
76 #include "services/memoryService.hpp"
77 #include "utilities/debug.hpp"
78 #include "utilities/formatBuffer.hpp"
79 #include "utilities/macros.hpp"
80 #include "utilities/stack.inline.hpp"
81 #include "utilities/vmError.hpp"
82 #if INCLUDE_JVMCI
83 #include "jvmci/jvmci.hpp"
84 #endif
85
86 SerialHeap* SerialHeap::heap() {
87 return named_heap<SerialHeap>(CollectedHeap::Serial);
88 }
89
90 SerialHeap::SerialHeap() :
91 CollectedHeap(),
92 _young_gen(nullptr),
93 _old_gen(nullptr),
94 _rem_set(nullptr),
95 _gc_policy_counters(new GCPolicyCounters("Copy:MSC", 2, 2)),
96 _incremental_collection_failed(false),
97 _young_manager(nullptr),
98 _old_manager(nullptr),
99 _eden_pool(nullptr),
100 _survivor_pool(nullptr),
101 _old_pool(nullptr) {
102 _young_manager = new GCMemoryManager("Copy");
103 _old_manager = new GCMemoryManager("MarkSweepCompact");
104 }
105
106 void SerialHeap::initialize_serviceability() {
107 DefNewGeneration* young = young_gen();
108
109 // Add a memory pool for each space and young gen doesn't
110 // support low memory detection as it is expected to get filled up.
111 _eden_pool = new ContiguousSpacePool(young->eden(),
112 "Eden Space",
113 young->max_eden_size(),
114 false /* support_usage_threshold */);
115 _survivor_pool = new SurvivorContiguousSpacePool(young,
116 "Survivor Space",
117 young->max_survivor_size(),
118 false /* support_usage_threshold */);
119 TenuredGeneration* old = old_gen();
120 _old_pool = new TenuredGenerationPool(old, "Tenured Gen", true);
121
122 _young_manager->add_pool(_eden_pool);
123 _young_manager->add_pool(_survivor_pool);
124 young->set_gc_manager(_young_manager);
125
126 _old_manager->add_pool(_eden_pool);
127 _old_manager->add_pool(_survivor_pool);
128 _old_manager->add_pool(_old_pool);
129 old->set_gc_manager(_old_manager);
130 }
131
132 GrowableArray<GCMemoryManager*> SerialHeap::memory_managers() {
133 GrowableArray<GCMemoryManager*> memory_managers(2);
134 memory_managers.append(_young_manager);
135 memory_managers.append(_old_manager);
136 return memory_managers;
137 }
138
139 GrowableArray<MemoryPool*> SerialHeap::memory_pools() {
140 GrowableArray<MemoryPool*> memory_pools(3);
141 memory_pools.append(_eden_pool);
142 memory_pools.append(_survivor_pool);
143 memory_pools.append(_old_pool);
144 return memory_pools;
145 }
146
147 void SerialHeap::safepoint_synchronize_begin() {
148 if (UseStringDeduplication) {
149 SuspendibleThreadSet::synchronize();
150 }
151 }
152
153 void SerialHeap::safepoint_synchronize_end() {
154 if (UseStringDeduplication) {
155 SuspendibleThreadSet::desynchronize();
156 }
157 }
158
159 HeapWord* SerialHeap::allocate_loaded_archive_space(size_t word_size) {
160 MutexLocker ml(Heap_lock);
161 return old_gen()->allocate(word_size, false /* is_tlab */);
162 }
163
164 void SerialHeap::complete_loaded_archive_space(MemRegion archive_space) {
165 assert(old_gen()->used_region().contains(archive_space), "Archive space not contained in old gen");
166 old_gen()->complete_loaded_archive_space(archive_space);
167 }
168
169 void SerialHeap::pin_object(JavaThread* thread, oop obj) {
170 GCLocker::lock_critical(thread);
171 }
172
173 void SerialHeap::unpin_object(JavaThread* thread, oop obj) {
174 GCLocker::unlock_critical(thread);
175 }
176
177 jint SerialHeap::initialize() {
178 // Allocate space for the heap.
179
180 ReservedHeapSpace heap_rs = allocate(HeapAlignment);
181
182 if (!heap_rs.is_reserved()) {
183 vm_shutdown_during_initialization(
184 "Could not reserve enough space for object heap");
185 return JNI_ENOMEM;
186 }
187
188 initialize_reserved_region(heap_rs);
189
190 ReservedSpace young_rs = heap_rs.first_part(MaxNewSize);
191 ReservedSpace old_rs = heap_rs.last_part(MaxNewSize);
192
193 _rem_set = new CardTableRS(heap_rs.region());
194 _rem_set->initialize(young_rs.base(), old_rs.base());
195
196 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
197 bs->initialize();
198 BarrierSet::set_barrier_set(bs);
199
200 _young_gen = new DefNewGeneration(young_rs, NewSize, MinNewSize, MaxNewSize);
201 _old_gen = new TenuredGeneration(old_rs, OldSize, MinOldSize, MaxOldSize, rem_set());
202
203 GCInitLogger::print();
204
205 return JNI_OK;
206 }
207
208 ReservedHeapSpace SerialHeap::allocate(size_t alignment) {
209 // Now figure out the total size.
210 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
211 assert(alignment % pageSize == 0, "Must be");
212
213 // Check for overflow.
214 size_t total_reserved = MaxNewSize + MaxOldSize;
215 if (total_reserved < MaxNewSize) {
216 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
217 "the maximum representable size");
218 }
219 assert(total_reserved % alignment == 0,
220 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
221 SIZE_FORMAT, total_reserved, alignment);
222
223 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
224 size_t used_page_size = heap_rs.page_size();
225
226 os::trace_page_sizes("Heap",
227 MinHeapSize,
228 total_reserved,
229 heap_rs.base(),
230 heap_rs.size(),
231 used_page_size);
232
233 return heap_rs;
234 }
235
236 class GenIsScavengable : public BoolObjectClosure {
237 public:
238 bool do_object_b(oop obj) {
239 return SerialHeap::heap()->is_in_young(obj);
240 }
241 };
242
243 static GenIsScavengable _is_scavengable;
244
245 void SerialHeap::post_initialize() {
246 CollectedHeap::post_initialize();
247
248 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
249
250 def_new_gen->ref_processor_init();
251
252 SerialFullGC::initialize();
253
254 ScavengableNMethods::initialize(&_is_scavengable);
255 }
256
257 PreGenGCValues SerialHeap::get_pre_gc_values() const {
258 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
259
260 return PreGenGCValues(def_new_gen->used(),
261 def_new_gen->capacity(),
262 def_new_gen->eden()->used(),
263 def_new_gen->eden()->capacity(),
264 def_new_gen->from()->used(),
265 def_new_gen->from()->capacity(),
266 old_gen()->used(),
267 old_gen()->capacity());
268 }
269
270 size_t SerialHeap::capacity() const {
271 return _young_gen->capacity() + _old_gen->capacity();
272 }
273
274 size_t SerialHeap::used() const {
275 return _young_gen->used() + _old_gen->used();
276 }
277
278 size_t SerialHeap::max_capacity() const {
279 return _young_gen->max_capacity() + _old_gen->max_capacity();
280 }
281
282 // Return true if any of the following is true:
283 // . the allocation won't fit into the current young gen heap
284 // . gc locker is occupied (jni critical section)
285 // . heap memory is tight -- the most recent previous collection
286 // was a full collection because a partial collection (would
287 // have) failed and is likely to fail again
288 bool SerialHeap::should_try_older_generation_allocation(size_t word_size) const {
289 size_t young_capacity = _young_gen->capacity_before_gc();
290 return (word_size > heap_word_size(young_capacity))
291 || GCLocker::is_active_and_needs_gc()
292 || incremental_collection_failed();
293 }
294
295 HeapWord* SerialHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
296 HeapWord* result = nullptr;
297 if (_old_gen->should_allocate(size, is_tlab)) {
298 result = _old_gen->expand_and_allocate(size, is_tlab);
299 }
300 if (result == nullptr) {
301 if (_young_gen->should_allocate(size, is_tlab)) {
302 result = _young_gen->expand_and_allocate(size, is_tlab);
303 }
304 }
305 assert(result == nullptr || is_in_reserved(result), "result not in heap");
306 return result;
307 }
308
309 HeapWord* SerialHeap::mem_allocate_work(size_t size,
310 bool is_tlab) {
311
312 HeapWord* result = nullptr;
313
314 // Loop until the allocation is satisfied, or unsatisfied after GC.
315 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
316
317 // First allocation attempt is lock-free.
318 Generation *young = _young_gen;
319 if (young->should_allocate(size, is_tlab)) {
320 result = young->par_allocate(size, is_tlab);
321 if (result != nullptr) {
322 assert(is_in_reserved(result), "result not in heap");
323 return result;
324 }
325 }
326 uint gc_count_before; // Read inside the Heap_lock locked region.
327 {
328 MutexLocker ml(Heap_lock);
329 log_trace(gc, alloc)("SerialHeap::mem_allocate_work: attempting locked slow path allocation");
330 // Note that only large objects get a shot at being
331 // allocated in later generations.
332 bool first_only = !should_try_older_generation_allocation(size);
333
334 result = attempt_allocation(size, is_tlab, first_only);
335 if (result != nullptr) {
336 assert(is_in_reserved(result), "result not in heap");
337 return result;
338 }
339
340 if (GCLocker::is_active_and_needs_gc()) {
341 if (is_tlab) {
342 return nullptr; // Caller will retry allocating individual object.
343 }
344 if (!is_maximal_no_gc()) {
345 // Try and expand heap to satisfy request.
346 result = expand_heap_and_allocate(size, is_tlab);
347 // Result could be null if we are out of space.
348 if (result != nullptr) {
349 return result;
350 }
351 }
352
353 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
354 return nullptr; // We didn't get to do a GC and we didn't get any memory.
355 }
356
357 // If this thread is not in a jni critical section, we stall
358 // the requestor until the critical section has cleared and
359 // GC allowed. When the critical section clears, a GC is
360 // initiated by the last thread exiting the critical section; so
361 // we retry the allocation sequence from the beginning of the loop,
362 // rather than causing more, now probably unnecessary, GC attempts.
363 JavaThread* jthr = JavaThread::current();
364 if (!jthr->in_critical()) {
365 MutexUnlocker mul(Heap_lock);
366 // Wait for JNI critical section to be exited
367 GCLocker::stall_until_clear();
368 gclocker_stalled_count += 1;
369 continue;
370 } else {
371 if (CheckJNICalls) {
372 fatal("Possible deadlock due to allocating while"
373 " in jni critical section");
374 }
375 return nullptr;
376 }
377 }
378
379 // Read the gc count while the heap lock is held.
380 gc_count_before = total_collections();
381 }
382
383 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
384 VMThread::execute(&op);
385 if (op.prologue_succeeded()) {
386 result = op.result();
387 if (op.gc_locked()) {
388 assert(result == nullptr, "must be null if gc_locked() is true");
389 continue; // Retry and/or stall as necessary.
390 }
391
392 assert(result == nullptr || is_in_reserved(result),
393 "result not in heap");
394 return result;
395 }
396
397 // Give a warning if we seem to be looping forever.
398 if ((QueuedAllocationWarningCount > 0) &&
399 (try_count % QueuedAllocationWarningCount == 0)) {
400 log_warning(gc, ergo)("SerialHeap::mem_allocate_work retries %d times,"
401 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
402 }
403 }
404 }
405
406 HeapWord* SerialHeap::attempt_allocation(size_t size,
407 bool is_tlab,
408 bool first_only) {
409 HeapWord* res = nullptr;
410
411 if (_young_gen->should_allocate(size, is_tlab)) {
412 res = _young_gen->allocate(size, is_tlab);
413 if (res != nullptr || first_only) {
414 return res;
415 }
416 }
417
418 if (_old_gen->should_allocate(size, is_tlab)) {
419 res = _old_gen->allocate(size, is_tlab);
420 }
421
422 return res;
423 }
424
425 HeapWord* SerialHeap::mem_allocate(size_t size,
426 bool* gc_overhead_limit_was_exceeded) {
427 return mem_allocate_work(size,
428 false /* is_tlab */);
429 }
430
431 bool SerialHeap::must_clear_all_soft_refs() {
432 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
433 _gc_cause == GCCause::_wb_full_gc;
434 }
435
436 void SerialHeap::collect_generation(Generation* gen, bool full, size_t size,
437 bool is_tlab, bool run_verification, bool clear_soft_refs) {
438 FormatBuffer<> title("Collect gen: %s", gen->short_name());
439 GCTraceTime(Trace, gc, phases) t1(title);
440 TraceCollectorStats tcs(gen->counters());
441 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause(), heap()->is_young_gen(gen) ? "end of minor GC" : "end of major GC");
442
443 gen->stat_record()->invocations++;
444 gen->stat_record()->accumulated_time.start();
445
446 // Must be done anew before each collection because
447 // a previous collection will do mangling and will
448 // change top of some spaces.
449 record_gen_tops_before_GC();
450
451 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
452
453 if (run_verification && VerifyBeforeGC) {
454 Universe::verify("Before GC");
455 }
456 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
457
458 // Do collection work
459 {
460 save_marks(); // save marks for all gens
461
462 gen->collect(full, clear_soft_refs, size, is_tlab);
463 }
464
465 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
466
467 gen->stat_record()->accumulated_time.stop();
468
469 update_gc_stats(gen, full);
470
471 if (run_verification && VerifyAfterGC) {
472 Universe::verify("After GC");
473 }
474 }
475
476 void SerialHeap::do_collection(bool full,
477 bool clear_all_soft_refs,
478 size_t size,
479 bool is_tlab,
480 GenerationType max_generation) {
481 ResourceMark rm;
482 DEBUG_ONLY(Thread* my_thread = Thread::current();)
483
484 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
485 assert(my_thread->is_VM_thread(), "only VM thread");
486 assert(Heap_lock->is_locked(),
487 "the requesting thread should have the Heap_lock");
488 guarantee(!is_gc_active(), "collection is not reentrant");
489
490 if (GCLocker::check_active_before_gc()) {
491 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
492 }
493
494 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
495 soft_ref_policy()->should_clear_all_soft_refs();
496
497 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
498
499 IsGCActiveMark active_gc_mark;
500
501 bool complete = full && (max_generation == OldGen);
502 bool old_collects_young = complete && !ScavengeBeforeFullGC;
503 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
504
505 const PreGenGCValues pre_gc_values = get_pre_gc_values();
506
507 bool run_verification = total_collections() >= VerifyGCStartAt;
508 bool prepared_for_verification = false;
509 bool do_full_collection = false;
510
511 if (do_young_collection) {
512 GCIdMark gc_id_mark;
513 GCTraceCPUTime tcpu(((DefNewGeneration*)_young_gen)->gc_tracer());
514 GCTraceTime(Info, gc) t("Pause Young", nullptr, gc_cause(), true);
515
516 print_heap_before_gc();
517
518 if (run_verification && VerifyBeforeGC) {
519 prepare_for_verify();
520 prepared_for_verification = true;
521 }
522
523 gc_prologue(complete);
524 increment_total_collections(complete);
525
526 collect_generation(_young_gen,
527 full,
528 size,
529 is_tlab,
530 run_verification,
531 do_clear_all_soft_refs);
532
533 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
534 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
535 // Allocation request was met by young GC.
536 size = 0;
537 }
538
539 // Ask if young collection is enough. If so, do the final steps for young collection,
540 // and fallthrough to the end.
541 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
542 if (!do_full_collection) {
543 // Adjust generation sizes.
544 _young_gen->compute_new_size();
545
546 print_heap_change(pre_gc_values);
547
548 // Track memory usage and detect low memory after GC finishes
549 MemoryService::track_memory_usage();
550
551 gc_epilogue(complete);
552 }
553
554 print_heap_after_gc();
555
556 } else {
557 // No young collection, ask if we need to perform Full collection.
558 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
559 }
560
561 if (do_full_collection) {
562 GCIdMark gc_id_mark;
563 GCTraceCPUTime tcpu(SerialFullGC::gc_tracer());
564 GCTraceTime(Info, gc) t("Pause Full", nullptr, gc_cause(), true);
565
566 print_heap_before_gc();
567
568 if (!prepared_for_verification && run_verification && VerifyBeforeGC) {
569 prepare_for_verify();
570 }
571
572 if (!do_young_collection) {
573 gc_prologue(complete);
574 increment_total_collections(complete);
575 }
576
577 // Accounting quirk: total full collections would be incremented when "complete"
578 // is set, by calling increment_total_collections above. However, we also need to
579 // account Full collections that had "complete" unset.
580 if (!complete) {
581 increment_total_full_collections();
582 }
583
584 CodeCache::on_gc_marking_cycle_start();
585
586 ClassUnloadingContext ctx(1 /* num_nmethod_unlink_workers */,
587 false /* unregister_nmethods_during_purge */,
588 false /* lock_nmethod_free_separately */);
589
590 collect_generation(_old_gen,
591 full,
592 size,
593 is_tlab,
594 run_verification,
595 do_clear_all_soft_refs);
596
597 CodeCache::on_gc_marking_cycle_finish();
598 CodeCache::arm_all_nmethods();
599
600 // Adjust generation sizes.
601 _old_gen->compute_new_size();
602 _young_gen->compute_new_size();
603
604 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
605 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
606 DEBUG_ONLY(MetaspaceUtils::verify();)
607
608 // Need to clear claim bits for the next mark.
609 ClassLoaderDataGraph::clear_claimed_marks();
610
611 // Resize the metaspace capacity after full collections
612 MetaspaceGC::compute_new_size();
613
614 print_heap_change(pre_gc_values);
615
616 // Track memory usage and detect low memory after GC finishes
617 MemoryService::track_memory_usage();
618
619 // Need to tell the epilogue code we are done with Full GC, regardless what was
620 // the initial value for "complete" flag.
621 gc_epilogue(true);
622
623 print_heap_after_gc();
624 }
625 }
626
627 bool SerialHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
628 SerialHeap::GenerationType max_gen) const {
629 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
630 }
631
632 void SerialHeap::register_nmethod(nmethod* nm) {
633 ScavengableNMethods::register_nmethod(nm);
634 }
635
636 void SerialHeap::unregister_nmethod(nmethod* nm) {
637 ScavengableNMethods::unregister_nmethod(nm);
638 }
639
640 void SerialHeap::verify_nmethod(nmethod* nm) {
641 ScavengableNMethods::verify_nmethod(nm);
642 }
643
644 void SerialHeap::prune_scavengable_nmethods() {
645 ScavengableNMethods::prune_nmethods_not_into_young();
646 }
647
648 void SerialHeap::prune_unlinked_nmethods() {
649 ScavengableNMethods::prune_unlinked_nmethods();
650 }
651
652 HeapWord* SerialHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
653 GCCauseSetter x(this, GCCause::_allocation_failure);
654 HeapWord* result = nullptr;
655
656 assert(size != 0, "Precondition violated");
657 if (GCLocker::is_active_and_needs_gc()) {
658 // GC locker is active; instead of a collection we will attempt
659 // to expand the heap, if there's room for expansion.
660 if (!is_maximal_no_gc()) {
661 result = expand_heap_and_allocate(size, is_tlab);
662 }
663 return result; // Could be null if we are out of space.
664 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
665 // Do an incremental collection.
666 do_collection(false, // full
667 false, // clear_all_soft_refs
668 size, // size
669 is_tlab, // is_tlab
670 SerialHeap::OldGen); // max_generation
671 } else {
672 log_trace(gc)(" :: Trying full because partial may fail :: ");
673 // Try a full collection; see delta for bug id 6266275
674 // for the original code and why this has been simplified
675 // with from-space allocation criteria modified and
676 // such allocation moved out of the safepoint path.
677 do_collection(true, // full
678 false, // clear_all_soft_refs
679 size, // size
680 is_tlab, // is_tlab
681 SerialHeap::OldGen); // max_generation
682 }
683
684 result = attempt_allocation(size, is_tlab, false /*first_only*/);
685
686 if (result != nullptr) {
687 assert(is_in_reserved(result), "result not in heap");
688 return result;
689 }
690
691 // OK, collection failed, try expansion.
692 result = expand_heap_and_allocate(size, is_tlab);
693 if (result != nullptr) {
694 return result;
695 }
696
697 // If we reach this point, we're really out of memory. Try every trick
698 // we can to reclaim memory. Force collection of soft references. Force
699 // a complete compaction of the heap. Any additional methods for finding
700 // free memory should be here, especially if they are expensive. If this
701 // attempt fails, an OOM exception will be thrown.
702 {
703 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
704
705 do_collection(true, // full
706 true, // clear_all_soft_refs
707 size, // size
708 is_tlab, // is_tlab
709 SerialHeap::OldGen); // max_generation
710 }
711
712 result = attempt_allocation(size, is_tlab, false /* first_only */);
713 if (result != nullptr) {
714 assert(is_in_reserved(result), "result not in heap");
715 return result;
716 }
717
718 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
719 "Flag should have been handled and cleared prior to this point");
720
721 // What else? We might try synchronous finalization later. If the total
722 // space available is large enough for the allocation, then a more
723 // complete compaction phase than we've tried so far might be
724 // appropriate.
725 return nullptr;
726 }
727
728 void SerialHeap::process_roots(ScanningOption so,
729 OopClosure* strong_roots,
730 CLDClosure* strong_cld_closure,
731 CLDClosure* weak_cld_closure,
732 NMethodToOopClosure* code_roots) {
733 // General roots.
734 assert(code_roots != nullptr, "code root closure should always be set");
735
736 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
737
738 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
739 NMethodToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? nullptr : code_roots;
740
741 Threads::oops_do(strong_roots, roots_from_code_p);
742
743 OopStorageSet::strong_oops_do(strong_roots);
744
745 if (so & SO_ScavengeCodeCache) {
746 assert(code_roots != nullptr, "must supply closure for code cache");
747
748 // We only visit parts of the CodeCache when scavenging.
749 ScavengableNMethods::nmethods_do(code_roots);
750 }
751 if (so & SO_AllCodeCache) {
752 assert(code_roots != nullptr, "must supply closure for code cache");
753
754 // CMSCollector uses this to do intermediate-strength collections.
755 // We scan the entire code cache, since CodeCache::do_unloading is not called.
756 CodeCache::nmethods_do(code_roots);
757 }
758 }
759
760 bool SerialHeap::no_allocs_since_save_marks() {
761 return _young_gen->no_allocs_since_save_marks() &&
762 _old_gen->no_allocs_since_save_marks();
763 }
764
765 void SerialHeap::scan_evacuated_objs(YoungGenScanClosure* young_cl,
766 OldGenScanClosure* old_cl) {
767 do {
768 young_gen()->oop_since_save_marks_iterate(young_cl);
769 old_gen()->oop_since_save_marks_iterate(old_cl);
770 } while (!no_allocs_since_save_marks());
771 guarantee(young_gen()->promo_failure_scan_is_complete(), "Failed to finish scan");
772 }
773
774 // public collection interfaces
775 void SerialHeap::collect(GCCause::Cause cause) {
776 // The caller doesn't have the Heap_lock
777 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
778
779 unsigned int gc_count_before;
780 unsigned int full_gc_count_before;
781
782 {
783 MutexLocker ml(Heap_lock);
784 // Read the GC count while holding the Heap_lock
785 gc_count_before = total_collections();
786 full_gc_count_before = total_full_collections();
787 }
788
789 if (GCLocker::should_discard(cause, gc_count_before)) {
790 return;
791 }
792
793 bool should_run_young_gc = (cause == GCCause::_wb_young_gc)
794 || (cause == GCCause::_gc_locker)
795 DEBUG_ONLY(|| (cause == GCCause::_scavenge_alot));
796
797 const GenerationType max_generation = should_run_young_gc
798 ? YoungGen
799 : OldGen;
800
801 while (true) {
802 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
803 cause, max_generation);
804 VMThread::execute(&op);
805
806 if (!GCCause::is_explicit_full_gc(cause)) {
807 return;
808 }
809
810 {
811 MutexLocker ml(Heap_lock);
812 // Read the GC count while holding the Heap_lock
813 if (full_gc_count_before != total_full_collections()) {
814 return;
815 }
816 }
817
818 if (GCLocker::is_active_and_needs_gc()) {
819 // If GCLocker is active, wait until clear before retrying.
820 GCLocker::stall_until_clear();
821 }
822 }
823 }
824
825 void SerialHeap::do_full_collection(bool clear_all_soft_refs) {
826 do_full_collection(clear_all_soft_refs, OldGen);
827 }
828
829 void SerialHeap::do_full_collection(bool clear_all_soft_refs,
830 GenerationType last_generation) {
831 do_collection(true, // full
832 clear_all_soft_refs, // clear_all_soft_refs
833 0, // size
834 false, // is_tlab
835 last_generation); // last_generation
836 // Hack XXX FIX ME !!!
837 // A scavenge may not have been attempted, or may have
838 // been attempted and failed, because the old gen was too full
839 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
840 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
841 // This time allow the old gen to be collected as well
842 do_collection(true, // full
843 clear_all_soft_refs, // clear_all_soft_refs
844 0, // size
845 false, // is_tlab
846 OldGen); // last_generation
847 }
848 }
849
850 bool SerialHeap::is_in_young(const void* p) const {
851 bool result = p < _old_gen->reserved().start();
852 assert(result == _young_gen->is_in_reserved(p),
853 "incorrect test - result=%d, p=" PTR_FORMAT, result, p2i(p));
854 return result;
855 }
856
857 bool SerialHeap::requires_barriers(stackChunkOop obj) const {
858 return !is_in_young(obj);
859 }
860
861 // Returns "TRUE" iff "p" points into the committed areas of the heap.
862 bool SerialHeap::is_in(const void* p) const {
863 return _young_gen->is_in(p) || _old_gen->is_in(p);
864 }
865
866 void SerialHeap::object_iterate(ObjectClosure* cl) {
867 _young_gen->object_iterate(cl);
868 _old_gen->object_iterate(cl);
869 }
870
871 HeapWord* SerialHeap::block_start(const void* addr) const {
872 assert(is_in_reserved(addr), "block_start of address outside of heap");
873 if (_young_gen->is_in_reserved(addr)) {
874 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
875 return _young_gen->block_start(addr);
876 }
877
878 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
879 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
880 return _old_gen->block_start(addr);
881 }
882
883 bool SerialHeap::block_is_obj(const HeapWord* addr) const {
884 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
885 assert(block_start(addr) == addr, "addr must be a block start");
886
887 if (_young_gen->is_in_reserved(addr)) {
888 return _young_gen->eden()->is_in(addr)
889 || _young_gen->from()->is_in(addr)
890 || _young_gen->to() ->is_in(addr);
891 }
892
893 assert(_old_gen->is_in_reserved(addr), "must be in old-gen");
894 return addr < _old_gen->space()->top();
895 }
896
897 size_t SerialHeap::tlab_capacity(Thread* thr) const {
898 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
899 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
900 return _young_gen->tlab_capacity();
901 }
902
903 size_t SerialHeap::tlab_used(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_used();
907 }
908
909 size_t SerialHeap::unsafe_max_tlab_alloc(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->unsafe_max_tlab_alloc();
913 }
914
915 HeapWord* SerialHeap::allocate_new_tlab(size_t min_size,
916 size_t requested_size,
917 size_t* actual_size) {
918 HeapWord* result = mem_allocate_work(requested_size /* size */,
919 true /* is_tlab */);
920 if (result != nullptr) {
921 *actual_size = requested_size;
922 }
923
924 return result;
925 }
926
927 void SerialHeap::prepare_for_verify() {
928 ensure_parsability(false); // no need to retire TLABs
929 }
930
931 bool SerialHeap::is_maximal_no_gc() const {
932 // We don't expand young-gen except at a GC.
933 return _old_gen->is_maximal_no_gc();
934 }
935
936 void SerialHeap::save_marks() {
937 _young_gen->save_marks();
938 _old_gen->save_marks();
939 }
940
941 void SerialHeap::verify(VerifyOption option /* ignored */) {
942 log_debug(gc, verify)("%s", _old_gen->name());
943 _old_gen->verify();
944
945 log_debug(gc, verify)("%s", _young_gen->name());
946 _young_gen->verify();
947
948 log_debug(gc, verify)("RemSet");
949 rem_set()->verify();
950 }
951
952 void SerialHeap::print_on(outputStream* st) const {
953 if (_young_gen != nullptr) {
954 _young_gen->print_on(st);
955 }
956 if (_old_gen != nullptr) {
957 _old_gen->print_on(st);
958 }
959 MetaspaceUtils::print_on(st);
960 }
961
962 void SerialHeap::gc_threads_do(ThreadClosure* tc) const {
963 }
964
965 bool SerialHeap::print_location(outputStream* st, void* addr) const {
966 return BlockLocationPrinter<SerialHeap>::print_location(st, addr);
967 }
968
969 void SerialHeap::print_tracing_info() const {
970 if (log_is_enabled(Debug, gc, heap, exit)) {
971 LogStreamHandle(Debug, gc, heap, exit) lsh;
972 _young_gen->print_summary_info_on(&lsh);
973 _old_gen->print_summary_info_on(&lsh);
974 }
975 }
976
977 void SerialHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
978 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
979
980 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
981 HEAP_CHANGE_FORMAT" "
982 HEAP_CHANGE_FORMAT,
983 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
984 pre_gc_values.young_gen_used(),
985 pre_gc_values.young_gen_capacity(),
986 def_new_gen->used(),
987 def_new_gen->capacity()),
988 HEAP_CHANGE_FORMAT_ARGS("Eden",
989 pre_gc_values.eden_used(),
990 pre_gc_values.eden_capacity(),
991 def_new_gen->eden()->used(),
992 def_new_gen->eden()->capacity()),
993 HEAP_CHANGE_FORMAT_ARGS("From",
994 pre_gc_values.from_used(),
995 pre_gc_values.from_capacity(),
996 def_new_gen->from()->used(),
997 def_new_gen->from()->capacity()));
998 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
999 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
1000 pre_gc_values.old_gen_used(),
1001 pre_gc_values.old_gen_capacity(),
1002 old_gen()->used(),
1003 old_gen()->capacity()));
1004 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1005 }
1006
1007 void SerialHeap::gc_prologue(bool full) {
1008 // Fill TLAB's and such
1009 ensure_parsability(true); // retire TLABs
1010
1011 _old_gen->gc_prologue();
1012 };
1013
1014 void SerialHeap::gc_epilogue(bool full) {
1015 #if COMPILER2_OR_JVMCI
1016 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1017 #endif // COMPILER2_OR_JVMCI
1018
1019 resize_all_tlabs();
1020
1021 _young_gen->gc_epilogue(full);
1022 _old_gen->gc_epilogue();
1023
1024 MetaspaceCounters::update_performance_counters();
1025 };
1026
1027 #ifndef PRODUCT
1028 void SerialHeap::record_gen_tops_before_GC() {
1029 if (ZapUnusedHeapArea) {
1030 _young_gen->record_spaces_top();
1031 _old_gen->record_spaces_top();
1032 }
1033 }
1034 #endif // not PRODUCT