1 /*
2 * Copyright (c) 2000, 2022, 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/symbolTable.hpp"
28 #include "classfile/stringTable.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/defNewGeneration.hpp"
34 #include "gc/shared/adaptiveSizePolicy.hpp"
35 #include "gc/shared/cardTableBarrierSet.hpp"
36 #include "gc/shared/cardTableRS.hpp"
37 #include "gc/shared/collectedHeap.inline.hpp"
38 #include "gc/shared/collectorCounters.hpp"
39 #include "gc/shared/continuationGCSupport.inline.hpp"
40 #include "gc/shared/gcId.hpp"
41 #include "gc/shared/gcLocker.hpp"
42 #include "gc/shared/gcPolicyCounters.hpp"
43 #include "gc/shared/gcTrace.hpp"
44 #include "gc/shared/gcTraceTime.inline.hpp"
45 #include "gc/shared/genArguments.hpp"
46 #include "gc/shared/gcVMOperations.hpp"
47 #include "gc/shared/genCollectedHeap.hpp"
48 #include "gc/shared/genOopClosures.inline.hpp"
49 #include "gc/shared/generationSpec.hpp"
50 #include "gc/shared/gcInitLogger.hpp"
51 #include "gc/shared/locationPrinter.inline.hpp"
52 #include "gc/shared/oopStorage.inline.hpp"
53 #include "gc/shared/oopStorageSet.inline.hpp"
54 #include "gc/shared/oopStorageParState.inline.hpp"
55 #include "gc/shared/scavengableNMethods.hpp"
56 #include "gc/shared/space.hpp"
57 #include "gc/shared/strongRootsScope.hpp"
58 #include "gc/shared/weakProcessor.hpp"
59 #include "gc/shared/workerThread.hpp"
60 #include "memory/iterator.hpp"
61 #include "memory/metaspaceCounters.hpp"
62 #include "memory/metaspaceUtils.hpp"
63 #include "memory/resourceArea.hpp"
64 #include "memory/universe.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "runtime/continuation.hpp"
67 #include "runtime/handles.hpp"
68 #include "runtime/handles.inline.hpp"
69 #include "runtime/java.hpp"
70 #include "runtime/threads.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "services/memoryService.hpp"
73 #include "utilities/autoRestore.hpp"
74 #include "utilities/debug.hpp"
75 #include "utilities/formatBuffer.hpp"
76 #include "utilities/macros.hpp"
77 #include "utilities/stack.inline.hpp"
78 #include "utilities/vmError.hpp"
79 #if INCLUDE_JVMCI
80 #include "jvmci/jvmci.hpp"
81 #endif
82
83 GenCollectedHeap::GenCollectedHeap(Generation::Name young,
84 Generation::Name old,
85 const char* policy_counters_name) :
86 CollectedHeap(),
87 _young_gen(NULL),
88 _old_gen(NULL),
89 _young_gen_spec(new GenerationSpec(young,
90 NewSize,
91 MaxNewSize,
92 GenAlignment)),
93 _old_gen_spec(new GenerationSpec(old,
94 OldSize,
95 MaxOldSize,
96 GenAlignment)),
97 _rem_set(NULL),
98 _soft_ref_gen_policy(),
99 _size_policy(NULL),
100 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
101 _incremental_collection_failed(false),
102 _full_collections_completed(0),
103 _young_manager(NULL),
104 _old_manager(NULL) {
105 }
106
107 jint GenCollectedHeap::initialize() {
108 // While there are no constraints in the GC code that HeapWordSize
109 // be any particular value, there are multiple other areas in the
110 // system which believe this to be true (e.g. oop->object_size in some
111 // cases incorrectly returns the size in wordSize units rather than
112 // HeapWordSize).
113 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
114
115 // Allocate space for the heap.
116
117 ReservedHeapSpace heap_rs = allocate(HeapAlignment);
118
119 if (!heap_rs.is_reserved()) {
120 vm_shutdown_during_initialization(
121 "Could not reserve enough space for object heap");
122 return JNI_ENOMEM;
123 }
124
125 initialize_reserved_region(heap_rs);
126
127 _rem_set = create_rem_set(heap_rs.region());
128 _rem_set->initialize();
129 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
130 bs->initialize();
131 BarrierSet::set_barrier_set(bs);
132
133 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size());
134 _young_gen = _young_gen_spec->init(young_rs, rem_set());
135 ReservedSpace old_rs = heap_rs.last_part(_young_gen_spec->max_size());
136
137 old_rs = old_rs.first_part(_old_gen_spec->max_size());
138 _old_gen = _old_gen_spec->init(old_rs, rem_set());
139
140 GCInitLogger::print();
141
142 return JNI_OK;
143 }
144
145 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
146 return new CardTableRS(reserved_region);
147 }
148
149 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
150 size_t init_promo_size,
151 size_t init_survivor_size) {
152 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
153 _size_policy = new AdaptiveSizePolicy(init_eden_size,
154 init_promo_size,
155 init_survivor_size,
156 max_gc_pause_sec,
157 GCTimeRatio);
158 }
159
160 ReservedHeapSpace GenCollectedHeap::allocate(size_t alignment) {
161 // Now figure out the total size.
162 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
163 assert(alignment % pageSize == 0, "Must be");
164
165 // Check for overflow.
166 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
167 if (total_reserved < _young_gen_spec->max_size()) {
168 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
169 "the maximum representable size");
170 }
171 assert(total_reserved % alignment == 0,
172 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
173 SIZE_FORMAT, total_reserved, alignment);
174
175 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
176 size_t used_page_size = heap_rs.page_size();
177
178 os::trace_page_sizes("Heap",
179 MinHeapSize,
180 total_reserved,
181 used_page_size,
182 heap_rs.base(),
183 heap_rs.size());
184
185 return heap_rs;
186 }
187
188 class GenIsScavengable : public BoolObjectClosure {
189 public:
190 bool do_object_b(oop obj) {
191 return GenCollectedHeap::heap()->is_in_young(obj);
192 }
193 };
194
195 static GenIsScavengable _is_scavengable;
196
197 void GenCollectedHeap::post_initialize() {
198 CollectedHeap::post_initialize();
199 ref_processing_init();
200
201 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
202
203 initialize_size_policy(def_new_gen->eden()->capacity(),
204 _old_gen->capacity(),
205 def_new_gen->from()->capacity());
206
207 MarkSweep::initialize();
208
209 ScavengableNMethods::initialize(&_is_scavengable);
210 }
211
212 void GenCollectedHeap::ref_processing_init() {
213 _young_gen->ref_processor_init();
214 _old_gen->ref_processor_init();
215 }
216
217 PreGenGCValues GenCollectedHeap::get_pre_gc_values() const {
218 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
219
220 return PreGenGCValues(def_new_gen->used(),
221 def_new_gen->capacity(),
222 def_new_gen->eden()->used(),
223 def_new_gen->eden()->capacity(),
224 def_new_gen->from()->used(),
225 def_new_gen->from()->capacity(),
226 old_gen()->used(),
227 old_gen()->capacity());
228 }
229
230 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
231 return _young_gen_spec;
232 }
233
234 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
235 return _old_gen_spec;
236 }
237
238 size_t GenCollectedHeap::capacity() const {
239 return _young_gen->capacity() + _old_gen->capacity();
240 }
241
242 size_t GenCollectedHeap::used() const {
243 return _young_gen->used() + _old_gen->used();
244 }
245
246 void GenCollectedHeap::save_used_regions() {
247 _old_gen->save_used_region();
248 _young_gen->save_used_region();
249 }
250
251 size_t GenCollectedHeap::max_capacity() const {
252 return _young_gen->max_capacity() + _old_gen->max_capacity();
253 }
254
255 // Update the _full_collections_completed counter
256 // at the end of a stop-world full GC.
257 unsigned int GenCollectedHeap::update_full_collections_completed() {
258 assert(_full_collections_completed <= _total_full_collections,
259 "Can't complete more collections than were started");
260 _full_collections_completed = _total_full_collections;
261 return _full_collections_completed;
262 }
263
264 // Return true if any of the following is true:
265 // . the allocation won't fit into the current young gen heap
266 // . gc locker is occupied (jni critical section)
267 // . heap memory is tight -- the most recent previous collection
268 // was a full collection because a partial collection (would
269 // have) failed and is likely to fail again
270 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
271 size_t young_capacity = _young_gen->capacity_before_gc();
272 return (word_size > heap_word_size(young_capacity))
273 || GCLocker::is_active_and_needs_gc()
274 || incremental_collection_failed();
275 }
276
277 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
278 HeapWord* result = NULL;
279 if (_old_gen->should_allocate(size, is_tlab)) {
280 result = _old_gen->expand_and_allocate(size, is_tlab);
281 }
282 if (result == NULL) {
283 if (_young_gen->should_allocate(size, is_tlab)) {
284 result = _young_gen->expand_and_allocate(size, is_tlab);
285 }
286 }
287 assert(result == NULL || is_in_reserved(result), "result not in heap");
288 return result;
289 }
290
291 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
292 bool is_tlab,
293 bool* gc_overhead_limit_was_exceeded) {
294 // In general gc_overhead_limit_was_exceeded should be false so
295 // set it so here and reset it to true only if the gc time
296 // limit is being exceeded as checked below.
297 *gc_overhead_limit_was_exceeded = false;
298
299 HeapWord* result = NULL;
300
301 // Loop until the allocation is satisfied, or unsatisfied after GC.
302 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
303
304 // First allocation attempt is lock-free.
305 Generation *young = _young_gen;
306 if (young->should_allocate(size, is_tlab)) {
307 result = young->par_allocate(size, is_tlab);
308 if (result != NULL) {
309 assert(is_in_reserved(result), "result not in heap");
310 return result;
311 }
312 }
313 uint gc_count_before; // Read inside the Heap_lock locked region.
314 {
315 MutexLocker ml(Heap_lock);
316 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
317 // Note that only large objects get a shot at being
318 // allocated in later generations.
319 bool first_only = !should_try_older_generation_allocation(size);
320
321 result = attempt_allocation(size, is_tlab, first_only);
322 if (result != NULL) {
323 assert(is_in_reserved(result), "result not in heap");
324 return result;
325 }
326
327 if (GCLocker::is_active_and_needs_gc()) {
328 if (is_tlab) {
329 return NULL; // Caller will retry allocating individual object.
330 }
331 if (!is_maximal_no_gc()) {
332 // Try and expand heap to satisfy request.
333 result = expand_heap_and_allocate(size, is_tlab);
334 // Result could be null if we are out of space.
335 if (result != NULL) {
336 return result;
337 }
338 }
339
340 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
341 return NULL; // We didn't get to do a GC and we didn't get any memory.
342 }
343
344 // If this thread is not in a jni critical section, we stall
345 // the requestor until the critical section has cleared and
346 // GC allowed. When the critical section clears, a GC is
347 // initiated by the last thread exiting the critical section; so
348 // we retry the allocation sequence from the beginning of the loop,
349 // rather than causing more, now probably unnecessary, GC attempts.
350 JavaThread* jthr = JavaThread::current();
351 if (!jthr->in_critical()) {
352 MutexUnlocker mul(Heap_lock);
353 // Wait for JNI critical section to be exited
354 GCLocker::stall_until_clear();
355 gclocker_stalled_count += 1;
356 continue;
357 } else {
358 if (CheckJNICalls) {
359 fatal("Possible deadlock due to allocating while"
360 " in jni critical section");
361 }
362 return NULL;
363 }
364 }
365
366 // Read the gc count while the heap lock is held.
367 gc_count_before = total_collections();
368 }
369
370 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
371 VMThread::execute(&op);
372 if (op.prologue_succeeded()) {
373 result = op.result();
374 if (op.gc_locked()) {
375 assert(result == NULL, "must be NULL if gc_locked() is true");
376 continue; // Retry and/or stall as necessary.
377 }
378
379 // Allocation has failed and a collection
380 // has been done. If the gc time limit was exceeded the
381 // this time, return NULL so that an out-of-memory
382 // will be thrown. Clear gc_overhead_limit_exceeded
383 // so that the overhead exceeded does not persist.
384
385 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
386 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
387
388 if (limit_exceeded && softrefs_clear) {
389 *gc_overhead_limit_was_exceeded = true;
390 size_policy()->set_gc_overhead_limit_exceeded(false);
391 if (op.result() != NULL) {
392 CollectedHeap::fill_with_object(op.result(), size);
393 }
394 return NULL;
395 }
396 assert(result == NULL || is_in_reserved(result),
397 "result not in heap");
398 return result;
399 }
400
401 // Give a warning if we seem to be looping forever.
402 if ((QueuedAllocationWarningCount > 0) &&
403 (try_count % QueuedAllocationWarningCount == 0)) {
404 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
405 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
406 }
407 }
408 }
409
410 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
411 bool is_tlab,
412 bool first_only) {
413 HeapWord* res = NULL;
414
415 if (_young_gen->should_allocate(size, is_tlab)) {
416 res = _young_gen->allocate(size, is_tlab);
417 if (res != NULL || first_only) {
418 return res;
419 }
420 }
421
422 if (_old_gen->should_allocate(size, is_tlab)) {
423 res = _old_gen->allocate(size, is_tlab);
424 }
425
426 return res;
427 }
428
429 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
430 bool* gc_overhead_limit_was_exceeded) {
431 return mem_allocate_work(size,
432 false /* is_tlab */,
433 gc_overhead_limit_was_exceeded);
434 }
435
436 bool GenCollectedHeap::must_clear_all_soft_refs() {
437 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
438 _gc_cause == GCCause::_wb_full_gc;
439 }
440
441 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
442 bool is_tlab, bool run_verification, bool clear_soft_refs) {
443 FormatBuffer<> title("Collect gen: %s", gen->short_name());
444 GCTraceTime(Trace, gc, phases) t1(title);
445 TraceCollectorStats tcs(gen->counters());
446 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
447
448 gen->stat_record()->invocations++;
449 gen->stat_record()->accumulated_time.start();
450
451 // Must be done anew before each collection because
452 // a previous collection will do mangling and will
453 // change top of some spaces.
454 record_gen_tops_before_GC();
455
456 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
457
458 if (run_verification && VerifyBeforeGC) {
459 Universe::verify("Before GC");
460 }
461 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
462
463 // Do collection work
464 {
465 // Note on ref discovery: For what appear to be historical reasons,
466 // GCH enables and disabled (by enqueuing) refs discovery.
467 // In the future this should be moved into the generation's
468 // collect method so that ref discovery and enqueueing concerns
469 // are local to a generation. The collect method could return
470 // an appropriate indication in the case that notification on
471 // the ref lock was needed. This will make the treatment of
472 // weak refs more uniform (and indeed remove such concerns
473 // from GCH). XXX
474
475 save_marks(); // save marks for all gens
476 // We want to discover references, but not process them yet.
477 // This mode is disabled in process_discovered_references if the
478 // generation does some collection work, or in
479 // enqueue_discovered_references if the generation returns
480 // without doing any work.
481 ReferenceProcessor* rp = gen->ref_processor();
482 rp->start_discovery(clear_soft_refs);
483
484 gen->collect(full, clear_soft_refs, size, is_tlab);
485
486 rp->disable_discovery();
487 rp->verify_no_references_recorded();
488 }
489
490 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
491
492 gen->stat_record()->accumulated_time.stop();
493
494 update_gc_stats(gen, full);
495
496 if (run_verification && VerifyAfterGC) {
497 Universe::verify("After GC");
498 }
499 }
500
501 void GenCollectedHeap::do_collection(bool full,
502 bool clear_all_soft_refs,
503 size_t size,
504 bool is_tlab,
505 GenerationType max_generation) {
506 ResourceMark rm;
507 DEBUG_ONLY(Thread* my_thread = Thread::current();)
508
509 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
510 assert(my_thread->is_VM_thread(), "only VM thread");
511 assert(Heap_lock->is_locked(),
512 "the requesting thread should have the Heap_lock");
513 guarantee(!is_gc_active(), "collection is not reentrant");
514
515 if (GCLocker::check_active_before_gc()) {
516 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
517 }
518
519 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
520 soft_ref_policy()->should_clear_all_soft_refs();
521
522 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
523
524 AutoModifyRestore<bool> temporarily(_is_gc_active, true);
525
526 bool complete = full && (max_generation == OldGen);
527 bool old_collects_young = complete && !ScavengeBeforeFullGC;
528 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
529
530 const PreGenGCValues pre_gc_values = get_pre_gc_values();
531
532 bool run_verification = total_collections() >= VerifyGCStartAt;
533 bool prepared_for_verification = false;
534 bool do_full_collection = false;
535
536 if (do_young_collection) {
537 GCIdMark gc_id_mark;
538 GCTraceCPUTime tcpu;
539 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
540
541 print_heap_before_gc();
542
543 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
544 prepare_for_verify();
545 prepared_for_verification = true;
546 }
547
548 gc_prologue(complete);
549 increment_total_collections(complete);
550
551 collect_generation(_young_gen,
552 full,
553 size,
554 is_tlab,
555 run_verification && VerifyGCLevel <= 0,
556 do_clear_all_soft_refs);
557
558 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
559 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
560 // Allocation request was met by young GC.
561 size = 0;
562 }
563
564 // Ask if young collection is enough. If so, do the final steps for young collection,
565 // and fallthrough to the end.
566 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
567 if (!do_full_collection) {
568 // Adjust generation sizes.
569 _young_gen->compute_new_size();
570
571 print_heap_change(pre_gc_values);
572
573 // Track memory usage and detect low memory after GC finishes
574 MemoryService::track_memory_usage();
575
576 gc_epilogue(complete);
577 }
578
579 print_heap_after_gc();
580
581 } else {
582 // No young collection, ask if we need to perform Full collection.
583 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
584 }
585
586 if (do_full_collection) {
587 GCIdMark gc_id_mark;
588 GCTraceCPUTime tcpu;
589 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
590
591 print_heap_before_gc();
592
593 if (!prepared_for_verification && run_verification &&
594 VerifyGCLevel <= 1 && VerifyBeforeGC) {
595 prepare_for_verify();
596 }
597
598 if (!do_young_collection) {
599 gc_prologue(complete);
600 increment_total_collections(complete);
601 }
602
603 // Accounting quirk: total full collections would be incremented when "complete"
604 // is set, by calling increment_total_collections above. However, we also need to
605 // account Full collections that had "complete" unset.
606 if (!complete) {
607 increment_total_full_collections();
608 }
609
610 Continuations::on_gc_marking_cycle_start();
611 Continuations::arm_all_nmethods();
612
613 collect_generation(_old_gen,
614 full,
615 size,
616 is_tlab,
617 run_verification && VerifyGCLevel <= 1,
618 do_clear_all_soft_refs);
619
620 Continuations::on_gc_marking_cycle_finish();
621 Continuations::arm_all_nmethods();
622
623 // Adjust generation sizes.
624 _old_gen->compute_new_size();
625 _young_gen->compute_new_size();
626
627 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
628 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
629 DEBUG_ONLY(MetaspaceUtils::verify();)
630 // Resize the metaspace capacity after full collections
631 MetaspaceGC::compute_new_size();
632 update_full_collections_completed();
633
634 print_heap_change(pre_gc_values);
635
636 // Track memory usage and detect low memory after GC finishes
637 MemoryService::track_memory_usage();
638
639 // Need to tell the epilogue code we are done with Full GC, regardless what was
640 // the initial value for "complete" flag.
641 gc_epilogue(true);
642
643 print_heap_after_gc();
644 }
645 }
646
647 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
648 GenCollectedHeap::GenerationType max_gen) const {
649 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
650 }
651
652 void GenCollectedHeap::register_nmethod(nmethod* nm) {
653 ScavengableNMethods::register_nmethod(nm);
654 }
655
656 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
657 ScavengableNMethods::unregister_nmethod(nm);
658 }
659
660 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
661 ScavengableNMethods::verify_nmethod(nm);
662 }
663
664 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
665 // Do nothing.
666 }
667
668 void GenCollectedHeap::prune_scavengable_nmethods() {
669 ScavengableNMethods::prune_nmethods();
670 }
671
672 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
673 GCCauseSetter x(this, GCCause::_allocation_failure);
674 HeapWord* result = NULL;
675
676 assert(size != 0, "Precondition violated");
677 if (GCLocker::is_active_and_needs_gc()) {
678 // GC locker is active; instead of a collection we will attempt
679 // to expand the heap, if there's room for expansion.
680 if (!is_maximal_no_gc()) {
681 result = expand_heap_and_allocate(size, is_tlab);
682 }
683 return result; // Could be null if we are out of space.
684 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
685 // Do an incremental collection.
686 do_collection(false, // full
687 false, // clear_all_soft_refs
688 size, // size
689 is_tlab, // is_tlab
690 GenCollectedHeap::OldGen); // max_generation
691 } else {
692 log_trace(gc)(" :: Trying full because partial may fail :: ");
693 // Try a full collection; see delta for bug id 6266275
694 // for the original code and why this has been simplified
695 // with from-space allocation criteria modified and
696 // such allocation moved out of the safepoint path.
697 do_collection(true, // full
698 false, // clear_all_soft_refs
699 size, // size
700 is_tlab, // is_tlab
701 GenCollectedHeap::OldGen); // max_generation
702 }
703
704 result = attempt_allocation(size, is_tlab, false /*first_only*/);
705
706 if (result != NULL) {
707 assert(is_in_reserved(result), "result not in heap");
708 return result;
709 }
710
711 // OK, collection failed, try expansion.
712 result = expand_heap_and_allocate(size, is_tlab);
713 if (result != NULL) {
714 return result;
715 }
716
717 // If we reach this point, we're really out of memory. Try every trick
718 // we can to reclaim memory. Force collection of soft references. Force
719 // a complete compaction of the heap. Any additional methods for finding
720 // free memory should be here, especially if they are expensive. If this
721 // attempt fails, an OOM exception will be thrown.
722 {
723 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
724
725 do_collection(true, // full
726 true, // clear_all_soft_refs
727 size, // size
728 is_tlab, // is_tlab
729 GenCollectedHeap::OldGen); // max_generation
730 }
731
732 result = attempt_allocation(size, is_tlab, false /* first_only */);
733 if (result != NULL) {
734 assert(is_in_reserved(result), "result not in heap");
735 return result;
736 }
737
738 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
739 "Flag should have been handled and cleared prior to this point");
740
741 // What else? We might try synchronous finalization later. If the total
742 // space available is large enough for the allocation, then a more
743 // complete compaction phase than we've tried so far might be
744 // appropriate.
745 return NULL;
746 }
747
748 #ifdef ASSERT
749 class AssertNonScavengableClosure: public OopClosure {
750 public:
751 virtual void do_oop(oop* p) {
752 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
753 "Referent should not be scavengable."); }
754 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
755 };
756 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
757 #endif
758
759 void GenCollectedHeap::process_roots(ScanningOption so,
760 OopClosure* strong_roots,
761 CLDClosure* strong_cld_closure,
762 CLDClosure* weak_cld_closure,
763 CodeBlobToOopClosure* code_roots) {
764 // General roots.
765 assert(code_roots != NULL, "code root closure should always be set");
766
767 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
768
769 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
770 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
771
772 Threads::oops_do(strong_roots, roots_from_code_p);
773
774 OopStorageSet::strong_oops_do(strong_roots);
775
776 if (so & SO_ScavengeCodeCache) {
777 assert(code_roots != NULL, "must supply closure for code cache");
778
779 // We only visit parts of the CodeCache when scavenging.
780 ScavengableNMethods::nmethods_do(code_roots);
781 }
782 if (so & SO_AllCodeCache) {
783 assert(code_roots != NULL, "must supply closure for code cache");
784
785 // CMSCollector uses this to do intermediate-strength collections.
786 // We scan the entire code cache, since CodeCache::do_unloading is not called.
787 CodeCache::blobs_do(code_roots);
788 }
789 // Verify that the code cache contents are not subject to
790 // movement by a scavenging collection.
791 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
792 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
793 }
794
795 void GenCollectedHeap::full_process_roots(bool is_adjust_phase,
796 ScanningOption so,
797 bool only_strong_roots,
798 OopClosure* root_closure,
799 CLDClosure* cld_closure) {
800 // Called from either the marking phase or the adjust phase.
801 const bool is_marking_phase = !is_adjust_phase;
802
803 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase, is_marking_phase);
804 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
805
806 process_roots(so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
807 }
808
809 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
810 WeakProcessor::oops_do(root_closure);
811 }
812
813 bool GenCollectedHeap::no_allocs_since_save_marks() {
814 return _young_gen->no_allocs_since_save_marks() &&
815 _old_gen->no_allocs_since_save_marks();
816 }
817
818 // public collection interfaces
819
820 void GenCollectedHeap::collect(GCCause::Cause cause) {
821 if ((cause == GCCause::_wb_young_gc) ||
822 (cause == GCCause::_gc_locker)) {
823 // Young collection for WhiteBox or GCLocker.
824 collect(cause, YoungGen);
825 } else {
826 #ifdef ASSERT
827 if (cause == GCCause::_scavenge_alot) {
828 // Young collection only.
829 collect(cause, YoungGen);
830 } else {
831 // Stop-the-world full collection.
832 collect(cause, OldGen);
833 }
834 #else
835 // Stop-the-world full collection.
836 collect(cause, OldGen);
837 #endif
838 }
839 }
840
841 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
842 // The caller doesn't have the Heap_lock
843 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
844
845 unsigned int gc_count_before;
846 unsigned int full_gc_count_before;
847
848 {
849 MutexLocker ml(Heap_lock);
850 // Read the GC count while holding the Heap_lock
851 gc_count_before = total_collections();
852 full_gc_count_before = total_full_collections();
853 }
854
855 if (GCLocker::should_discard(cause, gc_count_before)) {
856 return;
857 }
858
859 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
860 cause, max_generation);
861 VMThread::execute(&op);
862 }
863
864 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
865 do_full_collection(clear_all_soft_refs, OldGen);
866 }
867
868 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
869 GenerationType last_generation) {
870 do_collection(true, // full
871 clear_all_soft_refs, // clear_all_soft_refs
872 0, // size
873 false, // is_tlab
874 last_generation); // last_generation
875 // Hack XXX FIX ME !!!
876 // A scavenge may not have been attempted, or may have
877 // been attempted and failed, because the old gen was too full
878 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
879 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
880 // This time allow the old gen to be collected as well
881 do_collection(true, // full
882 clear_all_soft_refs, // clear_all_soft_refs
883 0, // size
884 false, // is_tlab
885 OldGen); // last_generation
886 }
887 }
888
889 bool GenCollectedHeap::is_in_young(oop p) const {
890 bool result = cast_from_oop<HeapWord*>(p) < _old_gen->reserved().start();
891 assert(result == _young_gen->is_in_reserved(p),
892 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
893 return result;
894 }
895
896 bool GenCollectedHeap::requires_barriers(stackChunkOop obj) const {
897 return !is_in_young(obj);
898 }
899
900 // Returns "TRUE" iff "p" points into the committed areas of the heap.
901 bool GenCollectedHeap::is_in(const void* p) const {
902 return _young_gen->is_in(p) || _old_gen->is_in(p);
903 }
904
905 #ifdef ASSERT
906 // Don't implement this by using is_in_young(). This method is used
907 // in some cases to check that is_in_young() is correct.
908 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
909 assert(is_in_reserved(p) || p == NULL,
910 "Does not work if address is non-null and outside of the heap");
911 return p < _young_gen->reserved().end() && p != NULL;
912 }
913 #endif
914
915 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
916 _young_gen->oop_iterate(cl);
917 _old_gen->oop_iterate(cl);
918 }
919
920 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
921 _young_gen->object_iterate(cl);
922 _old_gen->object_iterate(cl);
923 }
924
925 Space* GenCollectedHeap::space_containing(const void* addr) const {
926 Space* res = _young_gen->space_containing(addr);
927 if (res != NULL) {
928 return res;
929 }
930 res = _old_gen->space_containing(addr);
931 assert(res != NULL, "Could not find containing space");
932 return res;
933 }
934
935 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
936 assert(is_in_reserved(addr), "block_start of address outside of heap");
937 if (_young_gen->is_in_reserved(addr)) {
938 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
939 return _young_gen->block_start(addr);
940 }
941
942 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
943 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
944 return _old_gen->block_start(addr);
945 }
946
947 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
948 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
949 assert(block_start(addr) == addr, "addr must be a block start");
950 if (_young_gen->is_in_reserved(addr)) {
951 return _young_gen->block_is_obj(addr);
952 }
953
954 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
955 return _old_gen->block_is_obj(addr);
956 }
957
958 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
959 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
960 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
961 return _young_gen->tlab_capacity();
962 }
963
964 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
965 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
966 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
967 return _young_gen->tlab_used();
968 }
969
970 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
971 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
972 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
973 return _young_gen->unsafe_max_tlab_alloc();
974 }
975
976 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
977 size_t requested_size,
978 size_t* actual_size) {
979 bool gc_overhead_limit_was_exceeded;
980 HeapWord* result = mem_allocate_work(requested_size /* size */,
981 true /* is_tlab */,
982 &gc_overhead_limit_was_exceeded);
983 if (result != NULL) {
984 *actual_size = requested_size;
985 }
986
987 return result;
988 }
989
990 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
991 // from the list headed by "*prev_ptr".
992 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
993 bool first = true;
994 size_t min_size = 0; // "first" makes this conceptually infinite.
995 ScratchBlock **smallest_ptr, *smallest;
996 ScratchBlock *cur = *prev_ptr;
997 while (cur) {
998 assert(*prev_ptr == cur, "just checking");
999 if (first || cur->num_words < min_size) {
1000 smallest_ptr = prev_ptr;
1001 smallest = cur;
1002 min_size = smallest->num_words;
1003 first = false;
1004 }
1005 prev_ptr = &cur->next;
1006 cur = cur->next;
1007 }
1008 smallest = *smallest_ptr;
1009 *smallest_ptr = smallest->next;
1010 return smallest;
1011 }
1012
1013 // Sort the scratch block list headed by res into decreasing size order,
1014 // and set "res" to the result.
1015 static void sort_scratch_list(ScratchBlock*& list) {
1016 ScratchBlock* sorted = NULL;
1017 ScratchBlock* unsorted = list;
1018 while (unsorted) {
1019 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1020 smallest->next = sorted;
1021 sorted = smallest;
1022 }
1023 list = sorted;
1024 }
1025
1026 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1027 size_t max_alloc_words) {
1028 ScratchBlock* res = NULL;
1029 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1030 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1031 sort_scratch_list(res);
1032 return res;
1033 }
1034
1035 void GenCollectedHeap::release_scratch() {
1036 _young_gen->reset_scratch();
1037 _old_gen->reset_scratch();
1038 }
1039
1040 void GenCollectedHeap::prepare_for_verify() {
1041 ensure_parsability(false); // no need to retire TLABs
1042 }
1043
1044 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1045 bool old_to_young) {
1046 if (old_to_young) {
1047 cl->do_generation(_old_gen);
1048 cl->do_generation(_young_gen);
1049 } else {
1050 cl->do_generation(_young_gen);
1051 cl->do_generation(_old_gen);
1052 }
1053 }
1054
1055 bool GenCollectedHeap::is_maximal_no_gc() const {
1056 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1057 }
1058
1059 void GenCollectedHeap::save_marks() {
1060 _young_gen->save_marks();
1061 _old_gen->save_marks();
1062 }
1063
1064 GenCollectedHeap* GenCollectedHeap::heap() {
1065 // SerialHeap is the only subtype of GenCollectedHeap.
1066 return named_heap<GenCollectedHeap>(CollectedHeap::Serial);
1067 }
1068
1069 #if INCLUDE_SERIALGC
1070 void GenCollectedHeap::prepare_for_compaction() {
1071 // Start by compacting into same gen.
1072 CompactPoint cp(_old_gen);
1073 _old_gen->prepare_for_compaction(&cp);
1074 _young_gen->prepare_for_compaction(&cp);
1075 }
1076 #endif // INCLUDE_SERIALGC
1077
1078 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1079 log_debug(gc, verify)("%s", _old_gen->name());
1080 _old_gen->verify();
1081
1082 log_debug(gc, verify)("%s", _old_gen->name());
1083 _young_gen->verify();
1084
1085 log_debug(gc, verify)("RemSet");
1086 rem_set()->verify();
1087 }
1088
1089 void GenCollectedHeap::print_on(outputStream* st) const {
1090 if (_young_gen != NULL) {
1091 _young_gen->print_on(st);
1092 }
1093 if (_old_gen != NULL) {
1094 _old_gen->print_on(st);
1095 }
1096 MetaspaceUtils::print_on(st);
1097 }
1098
1099 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1100 }
1101
1102 bool GenCollectedHeap::print_location(outputStream* st, void* addr) const {
1103 return BlockLocationPrinter<GenCollectedHeap>::print_location(st, addr);
1104 }
1105
1106 void GenCollectedHeap::print_tracing_info() const {
1107 if (log_is_enabled(Debug, gc, heap, exit)) {
1108 LogStreamHandle(Debug, gc, heap, exit) lsh;
1109 _young_gen->print_summary_info_on(&lsh);
1110 _old_gen->print_summary_info_on(&lsh);
1111 }
1112 }
1113
1114 void GenCollectedHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
1115 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
1116
1117 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
1118 HEAP_CHANGE_FORMAT" "
1119 HEAP_CHANGE_FORMAT,
1120 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
1121 pre_gc_values.young_gen_used(),
1122 pre_gc_values.young_gen_capacity(),
1123 def_new_gen->used(),
1124 def_new_gen->capacity()),
1125 HEAP_CHANGE_FORMAT_ARGS("Eden",
1126 pre_gc_values.eden_used(),
1127 pre_gc_values.eden_capacity(),
1128 def_new_gen->eden()->used(),
1129 def_new_gen->eden()->capacity()),
1130 HEAP_CHANGE_FORMAT_ARGS("From",
1131 pre_gc_values.from_used(),
1132 pre_gc_values.from_capacity(),
1133 def_new_gen->from()->used(),
1134 def_new_gen->from()->capacity()));
1135 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
1136 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
1137 pre_gc_values.old_gen_used(),
1138 pre_gc_values.old_gen_capacity(),
1139 old_gen()->used(),
1140 old_gen()->capacity()));
1141 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1142 }
1143
1144 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1145 private:
1146 bool _full;
1147 public:
1148 void do_generation(Generation* gen) {
1149 gen->gc_prologue(_full);
1150 }
1151 GenGCPrologueClosure(bool full) : _full(full) {};
1152 };
1153
1154 void GenCollectedHeap::gc_prologue(bool full) {
1155 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1156
1157 // Fill TLAB's and such
1158 ensure_parsability(true); // retire TLABs
1159
1160 // Walk generations
1161 GenGCPrologueClosure blk(full);
1162 generation_iterate(&blk, false); // not old-to-young.
1163 };
1164
1165 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1166 private:
1167 bool _full;
1168 public:
1169 void do_generation(Generation* gen) {
1170 gen->gc_epilogue(_full);
1171 }
1172 GenGCEpilogueClosure(bool full) : _full(full) {};
1173 };
1174
1175 void GenCollectedHeap::gc_epilogue(bool full) {
1176 #if COMPILER2_OR_JVMCI
1177 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1178 #endif // COMPILER2_OR_JVMCI
1179
1180 resize_all_tlabs();
1181
1182 GenGCEpilogueClosure blk(full);
1183 generation_iterate(&blk, false); // not old-to-young.
1184
1185 MetaspaceCounters::update_performance_counters();
1186 };
1187
1188 #ifndef PRODUCT
1189 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1190 private:
1191 public:
1192 void do_generation(Generation* gen) {
1193 gen->record_spaces_top();
1194 }
1195 };
1196
1197 void GenCollectedHeap::record_gen_tops_before_GC() {
1198 if (ZapUnusedHeapArea) {
1199 GenGCSaveTopsBeforeGCClosure blk;
1200 generation_iterate(&blk, false); // not old-to-young.
1201 }
1202 }
1203 #endif // not PRODUCT
1204
1205 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1206 public:
1207 void do_generation(Generation* gen) {
1208 gen->ensure_parsability();
1209 }
1210 };
1211
1212 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1213 CollectedHeap::ensure_parsability(retire_tlabs);
1214 GenEnsureParsabilityClosure ep_cl;
1215 generation_iterate(&ep_cl, false);
1216 }