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/serialFullGC.hpp"
34 #include "gc/serial/serialHeap.inline.hpp"
35 #include "gc/serial/serialMemoryPools.hpp"
36 #include "gc/serial/serialVMOperations.hpp"
37 #include "gc/serial/tenuredGeneration.inline.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.inline.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/isGCActiveMark.hpp"
52 #include "gc/shared/locationPrinter.inline.hpp"
53 #include "gc/shared/oopStorage.inline.hpp"
54 #include "gc/shared/oopStorageParState.inline.hpp"
55 #include "gc/shared/oopStorageSet.inline.hpp"
56 #include "gc/shared/scavengableNMethods.hpp"
57 #include "gc/shared/space.hpp"
58 #include "gc/shared/strongRootsScope.hpp"
59 #include "gc/shared/suspendibleThreadSet.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/mutexLocker.hpp"
72 #include "runtime/threads.hpp"
73 #include "runtime/vmThread.hpp"
74 #include "services/memoryManager.hpp"
75 #include "services/memoryService.hpp"
76 #include "utilities/debug.hpp"
77 #include "utilities/formatBuffer.hpp"
78 #include "utilities/macros.hpp"
79 #include "utilities/stack.inline.hpp"
80 #include "utilities/vmError.hpp"
81 #if INCLUDE_JVMCI
82 #include "jvmci/jvmci.hpp"
83 #endif
84
85 SerialHeap* SerialHeap::heap() {
86 return named_heap<SerialHeap>(CollectedHeap::Serial);
87 }
88
89 SerialHeap::SerialHeap() :
90 CollectedHeap(),
91 _young_gen(nullptr),
92 _old_gen(nullptr),
93 _rem_set(nullptr),
94 _gc_policy_counters(new GCPolicyCounters("Copy:MSC", 2, 2)),
95 _incremental_collection_failed(false),
96 _young_manager(nullptr),
97 _old_manager(nullptr),
98 _eden_pool(nullptr),
99 _survivor_pool(nullptr),
100 _old_pool(nullptr) {
101 _young_manager = new GCMemoryManager("Copy");
102 _old_manager = new GCMemoryManager("MarkSweepCompact");
103 }
104
105 void SerialHeap::initialize_serviceability() {
106 DefNewGeneration* young = young_gen();
107
108 // Add a memory pool for each space and young gen doesn't
109 // support low memory detection as it is expected to get filled up.
110 _eden_pool = new ContiguousSpacePool(young->eden(),
111 "Eden Space",
112 young->max_eden_size(),
113 false /* support_usage_threshold */);
114 _survivor_pool = new SurvivorContiguousSpacePool(young,
115 "Survivor Space",
116 young->max_survivor_size(),
117 false /* support_usage_threshold */);
118 TenuredGeneration* old = old_gen();
119 _old_pool = new TenuredGenerationPool(old, "Tenured Gen", true);
120
121 _young_manager->add_pool(_eden_pool);
122 _young_manager->add_pool(_survivor_pool);
123 young->set_gc_manager(_young_manager);
124
125 _old_manager->add_pool(_eden_pool);
126 _old_manager->add_pool(_survivor_pool);
127 _old_manager->add_pool(_old_pool);
128 old->set_gc_manager(_old_manager);
129 }
130
131 GrowableArray<GCMemoryManager*> SerialHeap::memory_managers() {
132 GrowableArray<GCMemoryManager*> memory_managers(2);
133 memory_managers.append(_young_manager);
134 memory_managers.append(_old_manager);
135 return memory_managers;
136 }
137
138 GrowableArray<MemoryPool*> SerialHeap::memory_pools() {
139 GrowableArray<MemoryPool*> memory_pools(3);
140 memory_pools.append(_eden_pool);
141 memory_pools.append(_survivor_pool);
142 memory_pools.append(_old_pool);
143 return memory_pools;
144 }
145
146 void SerialHeap::safepoint_synchronize_begin() {
147 if (UseStringDeduplication) {
148 SuspendibleThreadSet::synchronize();
149 }
150 }
151
152 void SerialHeap::safepoint_synchronize_end() {
153 if (UseStringDeduplication) {
154 SuspendibleThreadSet::desynchronize();
155 }
156 }
157
158 HeapWord* SerialHeap::allocate_loaded_archive_space(size_t word_size) {
159 MutexLocker ml(Heap_lock);
160 return old_gen()->allocate(word_size, false /* is_tlab */);
161 }
162
163 void SerialHeap::complete_loaded_archive_space(MemRegion archive_space) {
164 assert(old_gen()->used_region().contains(archive_space), "Archive space not contained in old gen");
165 old_gen()->complete_loaded_archive_space(archive_space);
166 }
167
168 void SerialHeap::pin_object(JavaThread* thread, oop obj) {
169 GCLocker::lock_critical(thread);
170 }
171
172 void SerialHeap::unpin_object(JavaThread* thread, oop obj) {
173 GCLocker::unlock_critical(thread);
174 }
175
176 jint SerialHeap::initialize() {
177 // Allocate space for the heap.
178
179 ReservedHeapSpace heap_rs = allocate(HeapAlignment);
180
181 if (!heap_rs.is_reserved()) {
182 vm_shutdown_during_initialization(
183 "Could not reserve enough space for object heap");
184 return JNI_ENOMEM;
185 }
186
187 initialize_reserved_region(heap_rs);
188
189 ReservedSpace young_rs = heap_rs.first_part(MaxNewSize);
190 ReservedSpace old_rs = heap_rs.last_part(MaxNewSize);
191
192 _rem_set = new CardTableRS(heap_rs.region());
193 _rem_set->initialize(young_rs.base(), old_rs.base());
194
195 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
196 bs->initialize();
197 BarrierSet::set_barrier_set(bs);
198
199 _young_gen = new DefNewGeneration(young_rs, NewSize, MinNewSize, MaxNewSize);
200 _old_gen = new TenuredGeneration(old_rs, OldSize, MinOldSize, MaxOldSize, rem_set());
201
202 GCInitLogger::print();
203
204 return JNI_OK;
205 }
206
207 ReservedHeapSpace SerialHeap::allocate(size_t alignment) {
208 // Now figure out the total size.
209 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
210 assert(alignment % pageSize == 0, "Must be");
211
212 // Check for overflow.
213 size_t total_reserved = MaxNewSize + MaxOldSize;
214 if (total_reserved < MaxNewSize) {
215 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
216 "the maximum representable size");
217 }
218 assert(total_reserved % alignment == 0,
219 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
220 SIZE_FORMAT, total_reserved, alignment);
221
222 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
223 size_t used_page_size = heap_rs.page_size();
224
225 os::trace_page_sizes("Heap",
226 MinHeapSize,
227 total_reserved,
228 heap_rs.base(),
229 heap_rs.size(),
230 used_page_size);
231
232 return heap_rs;
233 }
234
235 class GenIsScavengable : public BoolObjectClosure {
236 public:
237 bool do_object_b(oop obj) {
238 return SerialHeap::heap()->is_in_young(obj);
239 }
240 };
241
242 static GenIsScavengable _is_scavengable;
243
244 void SerialHeap::post_initialize() {
245 CollectedHeap::post_initialize();
246
247 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
248
249 def_new_gen->ref_processor_init();
250
251 SerialFullGC::initialize();
252
253 ScavengableNMethods::initialize(&_is_scavengable);
254 }
255
256 PreGenGCValues SerialHeap::get_pre_gc_values() const {
257 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
258
259 return PreGenGCValues(def_new_gen->used(),
260 def_new_gen->capacity(),
261 def_new_gen->eden()->used(),
262 def_new_gen->eden()->capacity(),
263 def_new_gen->from()->used(),
264 def_new_gen->from()->capacity(),
265 old_gen()->used(),
266 old_gen()->capacity());
267 }
268
269 size_t SerialHeap::capacity() const {
270 return _young_gen->capacity() + _old_gen->capacity();
271 }
272
273 size_t SerialHeap::used() const {
274 return _young_gen->used() + _old_gen->used();
275 }
276
277 size_t SerialHeap::max_capacity() const {
278 return _young_gen->max_capacity() + _old_gen->max_capacity();
279 }
280
281 // Return true if any of the following is true:
282 // . the allocation won't fit into the current young gen heap
283 // . gc locker is occupied (jni critical section)
284 // . heap memory is tight -- the most recent previous collection
285 // was a full collection because a partial collection (would
286 // have) failed and is likely to fail again
287 bool SerialHeap::should_try_older_generation_allocation(size_t word_size) const {
288 size_t young_capacity = _young_gen->capacity_before_gc();
289 return (word_size > heap_word_size(young_capacity))
290 || GCLocker::is_active_and_needs_gc()
291 || incremental_collection_failed();
292 }
293
294 HeapWord* SerialHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
295 HeapWord* result = nullptr;
296 if (_old_gen->should_allocate(size, is_tlab)) {
297 result = _old_gen->expand_and_allocate(size, is_tlab);
298 }
299 if (result == nullptr) {
300 if (_young_gen->should_allocate(size, is_tlab)) {
301 result = _young_gen->expand_and_allocate(size, is_tlab);
302 }
303 }
304 assert(result == nullptr || is_in_reserved(result), "result not in heap");
305 return result;
306 }
307
308 HeapWord* SerialHeap::mem_allocate_work(size_t size,
309 bool is_tlab) {
310
311 HeapWord* result = nullptr;
312
313 // Loop until the allocation is satisfied, or unsatisfied after GC.
314 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
315
316 // First allocation attempt is lock-free.
317 DefNewGeneration *young = _young_gen;
318 if (young->should_allocate(size, is_tlab)) {
319 result = young->par_allocate(size, is_tlab);
320 if (result != nullptr) {
321 assert(is_in_reserved(result), "result not in heap");
322 return result;
323 }
324 }
325 uint gc_count_before; // Read inside the Heap_lock locked region.
326 {
327 MutexLocker ml(Heap_lock);
328 log_trace(gc, alloc)("SerialHeap::mem_allocate_work: attempting locked slow path allocation");
329 // Note that only large objects get a shot at being
330 // allocated in later generations.
331 bool first_only = !should_try_older_generation_allocation(size);
332
333 result = attempt_allocation(size, is_tlab, first_only);
334 if (result != nullptr) {
335 assert(is_in_reserved(result), "result not in heap");
336 return result;
337 }
338
339 if (GCLocker::is_active_and_needs_gc()) {
340 if (is_tlab) {
341 return nullptr; // Caller will retry allocating individual object.
342 }
343 if (!is_maximal_no_gc()) {
344 // Try and expand heap to satisfy request.
345 result = expand_heap_and_allocate(size, is_tlab);
346 // Result could be null if we are out of space.
347 if (result != nullptr) {
348 return result;
349 }
350 }
351
352 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
353 return nullptr; // We didn't get to do a GC and we didn't get any memory.
354 }
355
356 // If this thread is not in a jni critical section, we stall
357 // the requestor until the critical section has cleared and
358 // GC allowed. When the critical section clears, a GC is
359 // initiated by the last thread exiting the critical section; so
360 // we retry the allocation sequence from the beginning of the loop,
361 // rather than causing more, now probably unnecessary, GC attempts.
362 JavaThread* jthr = JavaThread::current();
363 if (!jthr->in_critical()) {
364 MutexUnlocker mul(Heap_lock);
365 // Wait for JNI critical section to be exited
366 GCLocker::stall_until_clear();
367 gclocker_stalled_count += 1;
368 continue;
369 } else {
370 if (CheckJNICalls) {
371 fatal("Possible deadlock due to allocating while"
372 " in jni critical section");
373 }
374 return nullptr;
375 }
376 }
377
378 // Read the gc count while the heap lock is held.
379 gc_count_before = total_collections();
380 }
381
382 VM_SerialCollectForAllocation op(size, is_tlab, gc_count_before);
383 VMThread::execute(&op);
384 if (op.prologue_succeeded()) {
385 result = op.result();
386 if (op.gc_locked()) {
387 assert(result == nullptr, "must be null if gc_locked() is true");
388 continue; // Retry and/or stall as necessary.
389 }
390
391 assert(result == nullptr || is_in_reserved(result),
392 "result not in heap");
393 return result;
394 }
395
396 // Give a warning if we seem to be looping forever.
397 if ((QueuedAllocationWarningCount > 0) &&
398 (try_count % QueuedAllocationWarningCount == 0)) {
399 log_warning(gc, ergo)("SerialHeap::mem_allocate_work retries %d times,"
400 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
401 }
402 }
403 }
404
405 HeapWord* SerialHeap::attempt_allocation(size_t size,
406 bool is_tlab,
407 bool first_only) {
408 HeapWord* res = nullptr;
409
410 if (_young_gen->should_allocate(size, is_tlab)) {
411 res = _young_gen->allocate(size, is_tlab);
412 if (res != nullptr || first_only) {
413 return res;
414 }
415 }
416
417 if (_old_gen->should_allocate(size, is_tlab)) {
418 res = _old_gen->allocate(size, is_tlab);
419 }
420
421 return res;
422 }
423
424 HeapWord* SerialHeap::mem_allocate(size_t size,
425 bool* gc_overhead_limit_was_exceeded) {
426 return mem_allocate_work(size,
427 false /* is_tlab */);
428 }
429
430 bool SerialHeap::must_clear_all_soft_refs() {
431 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
432 _gc_cause == GCCause::_wb_full_gc;
433 }
434
435 bool SerialHeap::is_young_gc_safe() const {
436 if (!_young_gen->to()->is_empty()) {
437 return false;
438 }
439 return _old_gen->promotion_attempt_is_safe(_young_gen->used());
440 }
441
442 bool SerialHeap::do_young_collection(bool clear_soft_refs) {
443 if (!is_young_gc_safe()) {
444 return false;
445 }
446 IsSTWGCActiveMark gc_active_mark;
447 SvcGCMarker sgcm(SvcGCMarker::MINOR);
448 GCIdMark gc_id_mark;
449 GCTraceCPUTime tcpu(_young_gen->gc_tracer());
450 GCTraceTime(Info, gc) t("Pause Young", nullptr, gc_cause(), true);
451 TraceCollectorStats tcs(_young_gen->counters());
452 TraceMemoryManagerStats tmms(_young_gen->gc_manager(), gc_cause(), "end of minor GC");
453 print_heap_before_gc();
454 const PreGenGCValues pre_gc_values = get_pre_gc_values();
455
456 increment_total_collections(false);
457 const bool should_verify = total_collections() >= VerifyGCStartAt;
458 if (should_verify && VerifyBeforeGC) {
459 prepare_for_verify();
460 Universe::verify("Before GC");
461 }
462 gc_prologue(false);
463 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
464
465 save_marks();
466
467 bool result = _young_gen->collect(clear_soft_refs);
468
469 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
470
471 // Only update stats for successful young-gc
472 if (result) {
473 _old_gen->update_promote_stats();
474 }
475
476 if (should_verify && VerifyAfterGC) {
477 Universe::verify("After GC");
478 }
479
480 _young_gen->compute_new_size();
481
482 print_heap_change(pre_gc_values);
483
484 // Track memory usage and detect low memory after GC finishes
485 MemoryService::track_memory_usage();
486
487 gc_epilogue(false);
488
489 print_heap_after_gc();
490
491 return result;
492 }
493
494 void SerialHeap::register_nmethod(nmethod* nm) {
495 ScavengableNMethods::register_nmethod(nm);
496 }
497
498 void SerialHeap::unregister_nmethod(nmethod* nm) {
499 ScavengableNMethods::unregister_nmethod(nm);
500 }
501
502 void SerialHeap::verify_nmethod(nmethod* nm) {
503 ScavengableNMethods::verify_nmethod(nm);
504 }
505
506 void SerialHeap::prune_scavengable_nmethods() {
507 ScavengableNMethods::prune_nmethods_not_into_young();
508 }
509
510 void SerialHeap::prune_unlinked_nmethods() {
511 ScavengableNMethods::prune_unlinked_nmethods();
512 }
513
514 HeapWord* SerialHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
515 assert(size != 0, "precondition");
516
517 HeapWord* result = nullptr;
518
519 GCLocker::check_active_before_gc();
520 if (GCLocker::is_active_and_needs_gc()) {
521 // GC locker is active; instead of a collection we will attempt
522 // to expand the heap, if there's room for expansion.
523 if (!is_maximal_no_gc()) {
524 result = expand_heap_and_allocate(size, is_tlab);
525 }
526 return result; // Could be null if we are out of space.
527 }
528
529 // If young-gen can handle this allocation, attempt young-gc firstly.
530 bool should_run_young_gc = _young_gen->should_allocate(size, is_tlab);
531 collect_at_safepoint(!should_run_young_gc);
532
533 result = attempt_allocation(size, is_tlab, false /*first_only*/);
534 if (result != nullptr) {
535 return result;
536 }
537
538 // OK, collection failed, try expansion.
539 result = expand_heap_and_allocate(size, is_tlab);
540 if (result != nullptr) {
541 return result;
542 }
543
544 // If we reach this point, we're really out of memory. Try every trick
545 // we can to reclaim memory. Force collection of soft references. Force
546 // a complete compaction of the heap. Any additional methods for finding
547 // free memory should be here, especially if they are expensive. If this
548 // attempt fails, an OOM exception will be thrown.
549 {
550 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
551 const bool clear_all_soft_refs = true;
552 do_full_collection_no_gc_locker(clear_all_soft_refs);
553 }
554
555 result = attempt_allocation(size, is_tlab, false /* first_only */);
556 if (result != nullptr) {
557 return result;
558 }
559 // The previous full-gc can shrink the heap, so re-expand it.
560 result = expand_heap_and_allocate(size, is_tlab);
561 if (result != nullptr) {
562 return result;
563 }
564
565 // What else? We might try synchronous finalization later. If the total
566 // space available is large enough for the allocation, then a more
567 // complete compaction phase than we've tried so far might be
568 // appropriate.
569 return nullptr;
570 }
571
572 void SerialHeap::process_roots(ScanningOption so,
573 OopClosure* strong_roots,
574 CLDClosure* strong_cld_closure,
575 CLDClosure* weak_cld_closure,
576 NMethodToOopClosure* code_roots) {
577 // General roots.
578 assert(code_roots != nullptr, "code root closure should always be set");
579
580 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
581
582 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
583 NMethodToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? nullptr : code_roots;
584
585 Threads::oops_do(strong_roots, roots_from_code_p);
586
587 OopStorageSet::strong_oops_do(strong_roots);
588
589 if (so & SO_ScavengeCodeCache) {
590 assert(code_roots != nullptr, "must supply closure for code cache");
591
592 // We only visit parts of the CodeCache when scavenging.
593 ScavengableNMethods::nmethods_do(code_roots);
594 }
595 if (so & SO_AllCodeCache) {
596 assert(code_roots != nullptr, "must supply closure for code cache");
597
598 // CMSCollector uses this to do intermediate-strength collections.
599 // We scan the entire code cache, since CodeCache::do_unloading is not called.
600 CodeCache::nmethods_do(code_roots);
601 }
602 }
603
604 template <typename OopClosureType>
605 static void oop_iterate_from(OopClosureType* blk, ContiguousSpace* space, HeapWord** from) {
606 assert(*from != nullptr, "precondition");
607 HeapWord* t;
608 HeapWord* p = *from;
609
610 const intx interval = PrefetchScanIntervalInBytes;
611 do {
612 t = space->top();
613 while (p < t) {
614 Prefetch::write(p, interval);
615 p += cast_to_oop(p)->oop_iterate_size(blk);
616 }
617 } while (t < space->top());
618
619 *from = space->top();
620 }
621
622 void SerialHeap::scan_evacuated_objs(YoungGenScanClosure* young_cl,
623 OldGenScanClosure* old_cl) {
624 ContiguousSpace* to_space = young_gen()->to();
625 do {
626 oop_iterate_from(young_cl, to_space, &_young_gen_saved_top);
627 oop_iterate_from(old_cl, old_gen()->space(), &_old_gen_saved_top);
628 // Recheck to-space only, because postcondition of oop_iterate_from is no
629 // unscanned objs
630 } while (_young_gen_saved_top != to_space->top());
631 guarantee(young_gen()->promo_failure_scan_is_complete(), "Failed to finish scan");
632 }
633
634 void SerialHeap::try_collect_at_safepoint(bool full) {
635 assert(SafepointSynchronize::is_at_safepoint(), "precondition");
636 if (GCLocker::check_active_before_gc()) {
637 return;
638 }
639 collect_at_safepoint(full);
640 }
641
642 void SerialHeap::collect_at_safepoint(bool full) {
643 assert(!GCLocker::is_active(), "precondition");
644 bool clear_soft_refs = must_clear_all_soft_refs();
645
646 if (!full) {
647 bool success = do_young_collection(clear_soft_refs);
648 if (success) {
649 return;
650 }
651 // Upgrade to Full-GC if young-gc fails
652 }
653 do_full_collection_no_gc_locker(clear_soft_refs);
654 }
655
656 // public collection interfaces
657 void SerialHeap::collect(GCCause::Cause cause) {
658 // The caller doesn't have the Heap_lock
659 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
660
661 unsigned int gc_count_before;
662 unsigned int full_gc_count_before;
663
664 {
665 MutexLocker ml(Heap_lock);
666 // Read the GC count while holding the Heap_lock
667 gc_count_before = total_collections();
668 full_gc_count_before = total_full_collections();
669 }
670
671 if (GCLocker::should_discard(cause, gc_count_before)) {
672 return;
673 }
674
675 bool should_run_young_gc = (cause == GCCause::_wb_young_gc)
676 || (cause == GCCause::_gc_locker)
677 DEBUG_ONLY(|| (cause == GCCause::_scavenge_alot));
678
679 while (true) {
680 VM_SerialGCCollect op(!should_run_young_gc,
681 gc_count_before,
682 full_gc_count_before,
683 cause);
684 VMThread::execute(&op);
685
686 if (!GCCause::is_explicit_full_gc(cause)) {
687 return;
688 }
689
690 {
691 MutexLocker ml(Heap_lock);
692 // Read the GC count while holding the Heap_lock
693 if (full_gc_count_before != total_full_collections()) {
694 return;
695 }
696 }
697
698 if (GCLocker::is_active_and_needs_gc()) {
699 // If GCLocker is active, wait until clear before retrying.
700 GCLocker::stall_until_clear();
701 }
702 }
703 }
704
705 void SerialHeap::do_full_collection(bool clear_all_soft_refs) {
706 if (GCLocker::check_active_before_gc()) {
707 return;
708 }
709 do_full_collection_no_gc_locker(clear_all_soft_refs);
710 }
711
712 void SerialHeap::do_full_collection_no_gc_locker(bool clear_all_soft_refs) {
713 IsSTWGCActiveMark gc_active_mark;
714 SvcGCMarker sgcm(SvcGCMarker::FULL);
715 GCIdMark gc_id_mark;
716 GCTraceCPUTime tcpu(SerialFullGC::gc_tracer());
717 GCTraceTime(Info, gc) t("Pause Full", nullptr, gc_cause(), true);
718 TraceCollectorStats tcs(_old_gen->counters());
719 TraceMemoryManagerStats tmms(_old_gen->gc_manager(), gc_cause(), "end of major GC");
720 const PreGenGCValues pre_gc_values = get_pre_gc_values();
721 print_heap_before_gc();
722
723 increment_total_collections(true);
724 const bool should_verify = total_collections() >= VerifyGCStartAt;
725 if (should_verify && VerifyBeforeGC) {
726 prepare_for_verify();
727 Universe::verify("Before GC");
728 }
729
730 gc_prologue(true);
731 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
732 CodeCache::on_gc_marking_cycle_start();
733 ClassUnloadingContext ctx(1 /* num_nmethod_unlink_workers */,
734 false /* unregister_nmethods_during_purge */,
735 false /* lock_nmethod_free_separately */);
736
737 STWGCTimer* gc_timer = SerialFullGC::gc_timer();
738 gc_timer->register_gc_start();
739
740 SerialOldTracer* gc_tracer = SerialFullGC::gc_tracer();
741 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
742
743 pre_full_gc_dump(gc_timer);
744
745 SerialFullGC::invoke_at_safepoint(clear_all_soft_refs);
746
747 post_full_gc_dump(gc_timer);
748
749 gc_timer->register_gc_end();
750
751 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
752 CodeCache::on_gc_marking_cycle_finish();
753 CodeCache::arm_all_nmethods();
754 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
755
756 // Adjust generation sizes.
757 _old_gen->compute_new_size();
758 _young_gen->compute_new_size();
759
760 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
761 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
762 DEBUG_ONLY(MetaspaceUtils::verify();)
763
764 // Need to clear claim bits for the next mark.
765 ClassLoaderDataGraph::clear_claimed_marks();
766
767 _old_gen->update_promote_stats();
768
769 // Resize the metaspace capacity after full collections
770 MetaspaceGC::compute_new_size();
771
772 print_heap_change(pre_gc_values);
773
774 // Track memory usage and detect low memory after GC finishes
775 MemoryService::track_memory_usage();
776
777 // Need to tell the epilogue code we are done with Full GC, regardless what was
778 // the initial value for "complete" flag.
779 gc_epilogue(true);
780
781 print_heap_after_gc();
782
783 if (should_verify && VerifyAfterGC) {
784 Universe::verify("After GC");
785 }
786 }
787
788 bool SerialHeap::is_in_young(const void* p) const {
789 bool result = p < _old_gen->reserved().start();
790 assert(result == _young_gen->is_in_reserved(p),
791 "incorrect test - result=%d, p=" PTR_FORMAT, result, p2i(p));
792 return result;
793 }
794
795 bool SerialHeap::requires_barriers(stackChunkOop obj) const {
796 return !is_in_young(obj);
797 }
798
799 // Returns "TRUE" iff "p" points into the committed areas of the heap.
800 bool SerialHeap::is_in(const void* p) const {
801 return _young_gen->is_in(p) || _old_gen->is_in(p);
802 }
803
804 void SerialHeap::object_iterate(ObjectClosure* cl) {
805 _young_gen->object_iterate(cl);
806 _old_gen->object_iterate(cl);
807 }
808
809 HeapWord* SerialHeap::block_start(const void* addr) const {
810 assert(is_in_reserved(addr), "block_start of address outside of heap");
811 if (_young_gen->is_in_reserved(addr)) {
812 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
813 return _young_gen->block_start(addr);
814 }
815
816 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
817 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
818 return _old_gen->block_start(addr);
819 }
820
821 bool SerialHeap::block_is_obj(const HeapWord* addr) const {
822 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
823 assert(block_start(addr) == addr, "addr must be a block start");
824
825 if (_young_gen->is_in_reserved(addr)) {
826 return _young_gen->eden()->is_in(addr)
827 || _young_gen->from()->is_in(addr)
828 || _young_gen->to() ->is_in(addr);
829 }
830
831 assert(_old_gen->is_in_reserved(addr), "must be in old-gen");
832 return addr < _old_gen->space()->top();
833 }
834
835 size_t SerialHeap::tlab_capacity(Thread* thr) const {
836 // Only young-gen supports tlab allocation.
837 return _young_gen->tlab_capacity();
838 }
839
840 size_t SerialHeap::tlab_used(Thread* thr) const {
841 return _young_gen->tlab_used();
842 }
843
844 size_t SerialHeap::unsafe_max_tlab_alloc(Thread* thr) const {
845 return _young_gen->unsafe_max_tlab_alloc();
846 }
847
848 HeapWord* SerialHeap::allocate_new_tlab(size_t min_size,
849 size_t requested_size,
850 size_t* actual_size) {
851 HeapWord* result = mem_allocate_work(requested_size /* size */,
852 true /* is_tlab */);
853 if (result != nullptr) {
854 *actual_size = requested_size;
855 }
856
857 return result;
858 }
859
860 void SerialHeap::prepare_for_verify() {
861 ensure_parsability(false); // no need to retire TLABs
862 }
863
864 bool SerialHeap::is_maximal_no_gc() const {
865 // We don't expand young-gen except at a GC.
866 return _old_gen->is_maximal_no_gc();
867 }
868
869 void SerialHeap::save_marks() {
870 _young_gen_saved_top = _young_gen->to()->top();
871 _old_gen_saved_top = _old_gen->space()->top();
872 }
873
874 void SerialHeap::verify(VerifyOption option /* ignored */) {
875 log_debug(gc, verify)("%s", _old_gen->name());
876 _old_gen->verify();
877
878 log_debug(gc, verify)("%s", _young_gen->name());
879 _young_gen->verify();
880
881 log_debug(gc, verify)("RemSet");
882 rem_set()->verify();
883 }
884
885 void SerialHeap::print_on(outputStream* st) const {
886 if (_young_gen != nullptr) {
887 _young_gen->print_on(st);
888 }
889 if (_old_gen != nullptr) {
890 _old_gen->print_on(st);
891 }
892 MetaspaceUtils::print_on(st);
893 }
894
895 void SerialHeap::gc_threads_do(ThreadClosure* tc) const {
896 }
897
898 bool SerialHeap::print_location(outputStream* st, void* addr) const {
899 return BlockLocationPrinter<SerialHeap>::print_location(st, addr);
900 }
901
902 void SerialHeap::print_tracing_info() const {
903 // Does nothing
904 }
905
906 void SerialHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
907 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
908
909 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
910 HEAP_CHANGE_FORMAT" "
911 HEAP_CHANGE_FORMAT,
912 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
913 pre_gc_values.young_gen_used(),
914 pre_gc_values.young_gen_capacity(),
915 def_new_gen->used(),
916 def_new_gen->capacity()),
917 HEAP_CHANGE_FORMAT_ARGS("Eden",
918 pre_gc_values.eden_used(),
919 pre_gc_values.eden_capacity(),
920 def_new_gen->eden()->used(),
921 def_new_gen->eden()->capacity()),
922 HEAP_CHANGE_FORMAT_ARGS("From",
923 pre_gc_values.from_used(),
924 pre_gc_values.from_capacity(),
925 def_new_gen->from()->used(),
926 def_new_gen->from()->capacity()));
927 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
928 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
929 pre_gc_values.old_gen_used(),
930 pre_gc_values.old_gen_capacity(),
931 old_gen()->used(),
932 old_gen()->capacity()));
933 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
934 }
935
936 void SerialHeap::gc_prologue(bool full) {
937 // Fill TLAB's and such
938 ensure_parsability(true); // retire TLABs
939
940 _old_gen->gc_prologue();
941 };
942
943 void SerialHeap::gc_epilogue(bool full) {
944 #if COMPILER2_OR_JVMCI
945 assert(DerivedPointerTable::is_empty(), "derived pointer present");
946 #endif // COMPILER2_OR_JVMCI
947
948 resize_all_tlabs();
949
950 _young_gen->gc_epilogue(full);
951 _old_gen->gc_epilogue();
952
953 MetaspaceCounters::update_performance_counters();
954 };