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/slidingForwarding.hpp"
57 #include "gc/shared/space.hpp"
58 #include "gc/shared/strongRootsScope.hpp"
59 #include "gc/shared/weakProcessor.hpp"
60 #include "gc/shared/workerThread.hpp"
61 #include "memory/iterator.hpp"
62 #include "memory/metaspaceCounters.hpp"
63 #include "memory/metaspaceUtils.hpp"
64 #include "memory/resourceArea.hpp"
65 #include "memory/universe.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/continuation.hpp"
68 #include "runtime/handles.hpp"
69 #include "runtime/handles.inline.hpp"
70 #include "runtime/java.hpp"
71 #include "runtime/threads.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "services/memoryService.hpp"
74 #include "utilities/autoRestore.hpp"
75 #include "utilities/debug.hpp"
76 #include "utilities/formatBuffer.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/stack.inline.hpp"
79 #include "utilities/vmError.hpp"
80 #if INCLUDE_JVMCI
81 #include "jvmci/jvmci.hpp"
82 #endif
83
84 GenCollectedHeap::GenCollectedHeap(Generation::Name young,
85 Generation::Name old,
86 const char* policy_counters_name) :
87 CollectedHeap(),
88 _young_gen(NULL),
89 _old_gen(NULL),
90 _young_gen_spec(new GenerationSpec(young,
91 NewSize,
92 MaxNewSize,
93 GenAlignment)),
94 _old_gen_spec(new GenerationSpec(old,
95 OldSize,
96 MaxOldSize,
97 GenAlignment)),
98 _rem_set(NULL),
99 _soft_ref_gen_policy(),
100 _size_policy(NULL),
101 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
102 _incremental_collection_failed(false),
103 _full_collections_completed(0),
104 _young_manager(NULL),
105 _old_manager(NULL) {
106 }
107
108 jint GenCollectedHeap::initialize() {
109 // While there are no constraints in the GC code that HeapWordSize
110 // be any particular value, there are multiple other areas in the
111 // system which believe this to be true (e.g. oop->object_size in some
112 // cases incorrectly returns the size in wordSize units rather than
113 // HeapWordSize).
114 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
115
116 // Allocate space for the heap.
117
118 ReservedHeapSpace heap_rs = allocate(HeapAlignment);
119
120 if (!heap_rs.is_reserved()) {
121 vm_shutdown_during_initialization(
122 "Could not reserve enough space for object heap");
123 return JNI_ENOMEM;
124 }
125
126 initialize_reserved_region(heap_rs);
127 _forwarding = new SlidingForwarding(_reserved);
128
129 _rem_set = create_rem_set(heap_rs.region());
130 _rem_set->initialize();
131 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
132 bs->initialize();
133 BarrierSet::set_barrier_set(bs);
134
135 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size());
136 _young_gen = _young_gen_spec->init(young_rs, rem_set());
137 ReservedSpace old_rs = heap_rs.last_part(_young_gen_spec->max_size());
138
139 old_rs = old_rs.first_part(_old_gen_spec->max_size());
140 _old_gen = _old_gen_spec->init(old_rs, rem_set());
141
142 GCInitLogger::print();
143
144 return JNI_OK;
145 }
146
147 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
148 return new CardTableRS(reserved_region);
149 }
150
151 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
152 size_t init_promo_size,
153 size_t init_survivor_size) {
154 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
155 _size_policy = new AdaptiveSizePolicy(init_eden_size,
156 init_promo_size,
157 init_survivor_size,
158 max_gc_pause_sec,
159 GCTimeRatio);
160 }
161
162 ReservedHeapSpace GenCollectedHeap::allocate(size_t alignment) {
163 // Now figure out the total size.
164 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
165 assert(alignment % pageSize == 0, "Must be");
166
167 // Check for overflow.
168 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
169 if (total_reserved < _young_gen_spec->max_size()) {
170 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
171 "the maximum representable size");
172 }
173 assert(total_reserved % alignment == 0,
174 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
175 SIZE_FORMAT, total_reserved, alignment);
176
177 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
178 size_t used_page_size = heap_rs.page_size();
179
180 os::trace_page_sizes("Heap",
181 MinHeapSize,
182 total_reserved,
183 used_page_size,
184 heap_rs.base(),
185 heap_rs.size());
186
187 return heap_rs;
188 }
189
190 class GenIsScavengable : public BoolObjectClosure {
191 public:
192 bool do_object_b(oop obj) {
193 return GenCollectedHeap::heap()->is_in_young(obj);
194 }
195 };
196
197 static GenIsScavengable _is_scavengable;
198
199 void GenCollectedHeap::post_initialize() {
200 CollectedHeap::post_initialize();
201 ref_processing_init();
202
203 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
204
205 initialize_size_policy(def_new_gen->eden()->capacity(),
206 _old_gen->capacity(),
207 def_new_gen->from()->capacity());
208
209 MarkSweep::initialize();
210
211 ScavengableNMethods::initialize(&_is_scavengable);
212 }
213
214 void GenCollectedHeap::ref_processing_init() {
215 _young_gen->ref_processor_init();
216 _old_gen->ref_processor_init();
217 }
218
219 PreGenGCValues GenCollectedHeap::get_pre_gc_values() const {
220 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
221
222 return PreGenGCValues(def_new_gen->used(),
223 def_new_gen->capacity(),
224 def_new_gen->eden()->used(),
225 def_new_gen->eden()->capacity(),
226 def_new_gen->from()->used(),
227 def_new_gen->from()->capacity(),
228 old_gen()->used(),
229 old_gen()->capacity());
230 }
231
232 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
233 return _young_gen_spec;
234 }
235
236 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
237 return _old_gen_spec;
238 }
239
240 size_t GenCollectedHeap::capacity() const {
241 return _young_gen->capacity() + _old_gen->capacity();
242 }
243
244 size_t GenCollectedHeap::used() const {
245 return _young_gen->used() + _old_gen->used();
246 }
247
248 void GenCollectedHeap::save_used_regions() {
249 _old_gen->save_used_region();
250 _young_gen->save_used_region();
251 }
252
253 size_t GenCollectedHeap::max_capacity() const {
254 return _young_gen->max_capacity() + _old_gen->max_capacity();
255 }
256
257 // Update the _full_collections_completed counter
258 // at the end of a stop-world full GC.
259 unsigned int GenCollectedHeap::update_full_collections_completed() {
260 assert(_full_collections_completed <= _total_full_collections,
261 "Can't complete more collections than were started");
262 _full_collections_completed = _total_full_collections;
263 return _full_collections_completed;
264 }
265
266 // Return true if any of the following is true:
267 // . the allocation won't fit into the current young gen heap
268 // . gc locker is occupied (jni critical section)
269 // . heap memory is tight -- the most recent previous collection
270 // was a full collection because a partial collection (would
271 // have) failed and is likely to fail again
272 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
273 size_t young_capacity = _young_gen->capacity_before_gc();
274 return (word_size > heap_word_size(young_capacity))
275 || GCLocker::is_active_and_needs_gc()
276 || incremental_collection_failed();
277 }
278
279 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
280 HeapWord* result = NULL;
281 if (_old_gen->should_allocate(size, is_tlab)) {
282 result = _old_gen->expand_and_allocate(size, is_tlab);
283 }
284 if (result == NULL) {
285 if (_young_gen->should_allocate(size, is_tlab)) {
286 result = _young_gen->expand_and_allocate(size, is_tlab);
287 }
288 }
289 assert(result == NULL || is_in_reserved(result), "result not in heap");
290 return result;
291 }
292
293 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
294 bool is_tlab,
295 bool* gc_overhead_limit_was_exceeded) {
296 // In general gc_overhead_limit_was_exceeded should be false so
297 // set it so here and reset it to true only if the gc time
298 // limit is being exceeded as checked below.
299 *gc_overhead_limit_was_exceeded = false;
300
301 HeapWord* result = NULL;
302
303 // Loop until the allocation is satisfied, or unsatisfied after GC.
304 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
305
306 // First allocation attempt is lock-free.
307 Generation *young = _young_gen;
308 if (young->should_allocate(size, is_tlab)) {
309 result = young->par_allocate(size, is_tlab);
310 if (result != NULL) {
311 assert(is_in_reserved(result), "result not in heap");
312 return result;
313 }
314 }
315 uint gc_count_before; // Read inside the Heap_lock locked region.
316 {
317 MutexLocker ml(Heap_lock);
318 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
319 // Note that only large objects get a shot at being
320 // allocated in later generations.
321 bool first_only = !should_try_older_generation_allocation(size);
322
323 result = attempt_allocation(size, is_tlab, first_only);
324 if (result != NULL) {
325 assert(is_in_reserved(result), "result not in heap");
326 return result;
327 }
328
329 if (GCLocker::is_active_and_needs_gc()) {
330 if (is_tlab) {
331 return NULL; // Caller will retry allocating individual object.
332 }
333 if (!is_maximal_no_gc()) {
334 // Try and expand heap to satisfy request.
335 result = expand_heap_and_allocate(size, is_tlab);
336 // Result could be null if we are out of space.
337 if (result != NULL) {
338 return result;
339 }
340 }
341
342 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
343 return NULL; // We didn't get to do a GC and we didn't get any memory.
344 }
345
346 // If this thread is not in a jni critical section, we stall
347 // the requestor until the critical section has cleared and
348 // GC allowed. When the critical section clears, a GC is
349 // initiated by the last thread exiting the critical section; so
350 // we retry the allocation sequence from the beginning of the loop,
351 // rather than causing more, now probably unnecessary, GC attempts.
352 JavaThread* jthr = JavaThread::current();
353 if (!jthr->in_critical()) {
354 MutexUnlocker mul(Heap_lock);
355 // Wait for JNI critical section to be exited
356 GCLocker::stall_until_clear();
357 gclocker_stalled_count += 1;
358 continue;
359 } else {
360 if (CheckJNICalls) {
361 fatal("Possible deadlock due to allocating while"
362 " in jni critical section");
363 }
364 return NULL;
365 }
366 }
367
368 // Read the gc count while the heap lock is held.
369 gc_count_before = total_collections();
370 }
371
372 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
373 VMThread::execute(&op);
374 if (op.prologue_succeeded()) {
375 result = op.result();
376 if (op.gc_locked()) {
377 assert(result == NULL, "must be NULL if gc_locked() is true");
378 continue; // Retry and/or stall as necessary.
379 }
380
381 // Allocation has failed and a collection
382 // has been done. If the gc time limit was exceeded the
383 // this time, return NULL so that an out-of-memory
384 // will be thrown. Clear gc_overhead_limit_exceeded
385 // so that the overhead exceeded does not persist.
386
387 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
388 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
389
390 if (limit_exceeded && softrefs_clear) {
391 *gc_overhead_limit_was_exceeded = true;
392 size_policy()->set_gc_overhead_limit_exceeded(false);
393 if (op.result() != NULL) {
394 CollectedHeap::fill_with_object(op.result(), size);
395 }
396 return NULL;
397 }
398 assert(result == NULL || is_in_reserved(result),
399 "result not in heap");
400 return result;
401 }
402
403 // Give a warning if we seem to be looping forever.
404 if ((QueuedAllocationWarningCount > 0) &&
405 (try_count % QueuedAllocationWarningCount == 0)) {
406 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
407 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
408 }
409 }
410 }
411
412 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
413 bool is_tlab,
414 bool first_only) {
415 HeapWord* res = NULL;
416
417 if (_young_gen->should_allocate(size, is_tlab)) {
418 res = _young_gen->allocate(size, is_tlab);
419 if (res != NULL || first_only) {
420 return res;
421 }
422 }
423
424 if (_old_gen->should_allocate(size, is_tlab)) {
425 res = _old_gen->allocate(size, is_tlab);
426 }
427
428 return res;
429 }
430
431 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
432 bool* gc_overhead_limit_was_exceeded) {
433 return mem_allocate_work(size,
434 false /* is_tlab */,
435 gc_overhead_limit_was_exceeded);
436 }
437
438 bool GenCollectedHeap::must_clear_all_soft_refs() {
439 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
440 _gc_cause == GCCause::_wb_full_gc;
441 }
442
443 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
444 bool is_tlab, bool run_verification, bool clear_soft_refs) {
445 FormatBuffer<> title("Collect gen: %s", gen->short_name());
446 GCTraceTime(Trace, gc, phases) t1(title);
447 TraceCollectorStats tcs(gen->counters());
448 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
449
450 gen->stat_record()->invocations++;
451 gen->stat_record()->accumulated_time.start();
452
453 // Must be done anew before each collection because
454 // a previous collection will do mangling and will
455 // change top of some spaces.
456 record_gen_tops_before_GC();
457
458 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
459
460 if (run_verification && VerifyBeforeGC) {
461 Universe::verify("Before GC");
462 }
463 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
464
465 // Do collection work
466 {
467 // Note on ref discovery: For what appear to be historical reasons,
468 // GCH enables and disabled (by enqueuing) refs discovery.
469 // In the future this should be moved into the generation's
470 // collect method so that ref discovery and enqueueing concerns
471 // are local to a generation. The collect method could return
472 // an appropriate indication in the case that notification on
473 // the ref lock was needed. This will make the treatment of
474 // weak refs more uniform (and indeed remove such concerns
475 // from GCH). XXX
476
477 save_marks(); // save marks for all gens
478 // We want to discover references, but not process them yet.
479 // This mode is disabled in process_discovered_references if the
480 // generation does some collection work, or in
481 // enqueue_discovered_references if the generation returns
482 // without doing any work.
483 ReferenceProcessor* rp = gen->ref_processor();
484 rp->start_discovery(clear_soft_refs);
485
486 gen->collect(full, clear_soft_refs, size, is_tlab);
487
488 rp->disable_discovery();
489 rp->verify_no_references_recorded();
490 }
491
492 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
493
494 gen->stat_record()->accumulated_time.stop();
495
496 update_gc_stats(gen, full);
497
498 if (run_verification && VerifyAfterGC) {
499 Universe::verify("After GC");
500 }
501 }
502
503 void GenCollectedHeap::do_collection(bool full,
504 bool clear_all_soft_refs,
505 size_t size,
506 bool is_tlab,
507 GenerationType max_generation) {
508 ResourceMark rm;
509 DEBUG_ONLY(Thread* my_thread = Thread::current();)
510
511 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
512 assert(my_thread->is_VM_thread(), "only VM thread");
513 assert(Heap_lock->is_locked(),
514 "the requesting thread should have the Heap_lock");
515 guarantee(!is_gc_active(), "collection is not reentrant");
516
517 if (GCLocker::check_active_before_gc()) {
518 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
519 }
520
521 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
522 soft_ref_policy()->should_clear_all_soft_refs();
523
524 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
525
526 AutoModifyRestore<bool> temporarily(_is_gc_active, true);
527
528 bool complete = full && (max_generation == OldGen);
529 bool old_collects_young = complete && !ScavengeBeforeFullGC;
530 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
531
532 const PreGenGCValues pre_gc_values = get_pre_gc_values();
533
534 bool run_verification = total_collections() >= VerifyGCStartAt;
535 bool prepared_for_verification = false;
536 bool do_full_collection = false;
537
538 if (do_young_collection) {
539 GCIdMark gc_id_mark;
540 GCTraceCPUTime tcpu;
541 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
542
543 print_heap_before_gc();
544
545 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
546 prepare_for_verify();
547 prepared_for_verification = true;
548 }
549
550 gc_prologue(complete);
551 increment_total_collections(complete);
552
553 collect_generation(_young_gen,
554 full,
555 size,
556 is_tlab,
557 run_verification && VerifyGCLevel <= 0,
558 do_clear_all_soft_refs);
559
560 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
561 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
562 // Allocation request was met by young GC.
563 size = 0;
564 }
565
566 // Ask if young collection is enough. If so, do the final steps for young collection,
567 // and fallthrough to the end.
568 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
569 if (!do_full_collection) {
570 // Adjust generation sizes.
571 _young_gen->compute_new_size();
572
573 print_heap_change(pre_gc_values);
574
575 // Track memory usage and detect low memory after GC finishes
576 MemoryService::track_memory_usage();
577
578 gc_epilogue(complete);
579 }
580
581 print_heap_after_gc();
582
583 } else {
584 // No young collection, ask if we need to perform Full collection.
585 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
586 }
587
588 if (do_full_collection) {
589 GCIdMark gc_id_mark;
590 GCTraceCPUTime tcpu;
591 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
592
593 print_heap_before_gc();
594
595 if (!prepared_for_verification && run_verification &&
596 VerifyGCLevel <= 1 && VerifyBeforeGC) {
597 prepare_for_verify();
598 }
599
600 if (!do_young_collection) {
601 gc_prologue(complete);
602 increment_total_collections(complete);
603 }
604
605 // Accounting quirk: total full collections would be incremented when "complete"
606 // is set, by calling increment_total_collections above. However, we also need to
607 // account Full collections that had "complete" unset.
608 if (!complete) {
609 increment_total_full_collections();
610 }
611
612 Continuations::on_gc_marking_cycle_start();
613 Continuations::arm_all_nmethods();
614
615 collect_generation(_old_gen,
616 full,
617 size,
618 is_tlab,
619 run_verification && VerifyGCLevel <= 1,
620 do_clear_all_soft_refs);
621
622 Continuations::on_gc_marking_cycle_finish();
623 Continuations::arm_all_nmethods();
624
625 // Adjust generation sizes.
626 _old_gen->compute_new_size();
627 _young_gen->compute_new_size();
628
629 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
630 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
631 DEBUG_ONLY(MetaspaceUtils::verify();)
632 // Resize the metaspace capacity after full collections
633 MetaspaceGC::compute_new_size();
634 update_full_collections_completed();
635
636 print_heap_change(pre_gc_values);
637
638 // Track memory usage and detect low memory after GC finishes
639 MemoryService::track_memory_usage();
640
641 // Need to tell the epilogue code we are done with Full GC, regardless what was
642 // the initial value for "complete" flag.
643 gc_epilogue(true);
644
645 print_heap_after_gc();
646 }
647 }
648
649 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
650 GenCollectedHeap::GenerationType max_gen) const {
651 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
652 }
653
654 void GenCollectedHeap::register_nmethod(nmethod* nm) {
655 ScavengableNMethods::register_nmethod(nm);
656 }
657
658 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
659 ScavengableNMethods::unregister_nmethod(nm);
660 }
661
662 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
663 ScavengableNMethods::verify_nmethod(nm);
664 }
665
666 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
667 // Do nothing.
668 }
669
670 void GenCollectedHeap::prune_scavengable_nmethods() {
671 ScavengableNMethods::prune_nmethods();
672 }
673
674 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
675 GCCauseSetter x(this, GCCause::_allocation_failure);
676 HeapWord* result = NULL;
677
678 assert(size != 0, "Precondition violated");
679 if (GCLocker::is_active_and_needs_gc()) {
680 // GC locker is active; instead of a collection we will attempt
681 // to expand the heap, if there's room for expansion.
682 if (!is_maximal_no_gc()) {
683 result = expand_heap_and_allocate(size, is_tlab);
684 }
685 return result; // Could be null if we are out of space.
686 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
687 // Do an incremental collection.
688 do_collection(false, // full
689 false, // clear_all_soft_refs
690 size, // size
691 is_tlab, // is_tlab
692 GenCollectedHeap::OldGen); // max_generation
693 } else {
694 log_trace(gc)(" :: Trying full because partial may fail :: ");
695 // Try a full collection; see delta for bug id 6266275
696 // for the original code and why this has been simplified
697 // with from-space allocation criteria modified and
698 // such allocation moved out of the safepoint path.
699 do_collection(true, // full
700 false, // clear_all_soft_refs
701 size, // size
702 is_tlab, // is_tlab
703 GenCollectedHeap::OldGen); // max_generation
704 }
705
706 result = attempt_allocation(size, is_tlab, false /*first_only*/);
707
708 if (result != NULL) {
709 assert(is_in_reserved(result), "result not in heap");
710 return result;
711 }
712
713 // OK, collection failed, try expansion.
714 result = expand_heap_and_allocate(size, is_tlab);
715 if (result != NULL) {
716 return result;
717 }
718
719 // If we reach this point, we're really out of memory. Try every trick
720 // we can to reclaim memory. Force collection of soft references. Force
721 // a complete compaction of the heap. Any additional methods for finding
722 // free memory should be here, especially if they are expensive. If this
723 // attempt fails, an OOM exception will be thrown.
724 {
725 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
726
727 do_collection(true, // full
728 true, // clear_all_soft_refs
729 size, // size
730 is_tlab, // is_tlab
731 GenCollectedHeap::OldGen); // max_generation
732 }
733
734 result = attempt_allocation(size, is_tlab, false /* first_only */);
735 if (result != NULL) {
736 assert(is_in_reserved(result), "result not in heap");
737 return result;
738 }
739
740 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
741 "Flag should have been handled and cleared prior to this point");
742
743 // What else? We might try synchronous finalization later. If the total
744 // space available is large enough for the allocation, then a more
745 // complete compaction phase than we've tried so far might be
746 // appropriate.
747 return NULL;
748 }
749
750 #ifdef ASSERT
751 class AssertNonScavengableClosure: public OopClosure {
752 public:
753 virtual void do_oop(oop* p) {
754 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
755 "Referent should not be scavengable."); }
756 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
757 };
758 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
759 #endif
760
761 void GenCollectedHeap::process_roots(ScanningOption so,
762 OopClosure* strong_roots,
763 CLDClosure* strong_cld_closure,
764 CLDClosure* weak_cld_closure,
765 CodeBlobToOopClosure* code_roots) {
766 // General roots.
767 assert(code_roots != NULL, "code root closure should always be set");
768
769 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
770
771 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
772 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
773
774 Threads::oops_do(strong_roots, roots_from_code_p);
775
776 OopStorageSet::strong_oops_do(strong_roots);
777
778 if (so & SO_ScavengeCodeCache) {
779 assert(code_roots != NULL, "must supply closure for code cache");
780
781 // We only visit parts of the CodeCache when scavenging.
782 ScavengableNMethods::nmethods_do(code_roots);
783 }
784 if (so & SO_AllCodeCache) {
785 assert(code_roots != NULL, "must supply closure for code cache");
786
787 // CMSCollector uses this to do intermediate-strength collections.
788 // We scan the entire code cache, since CodeCache::do_unloading is not called.
789 CodeCache::blobs_do(code_roots);
790 }
791 // Verify that the code cache contents are not subject to
792 // movement by a scavenging collection.
793 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
794 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
795 }
796
797 void GenCollectedHeap::full_process_roots(bool is_adjust_phase,
798 ScanningOption so,
799 bool only_strong_roots,
800 OopClosure* root_closure,
801 CLDClosure* cld_closure) {
802 // Called from either the marking phase or the adjust phase.
803 const bool is_marking_phase = !is_adjust_phase;
804
805 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase, is_marking_phase);
806 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
807
808 process_roots(so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
809 }
810
811 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
812 WeakProcessor::oops_do(root_closure);
813 }
814
815 bool GenCollectedHeap::no_allocs_since_save_marks() {
816 return _young_gen->no_allocs_since_save_marks() &&
817 _old_gen->no_allocs_since_save_marks();
818 }
819
820 // public collection interfaces
821
822 void GenCollectedHeap::collect(GCCause::Cause cause) {
823 if ((cause == GCCause::_wb_young_gc) ||
824 (cause == GCCause::_gc_locker)) {
825 // Young collection for WhiteBox or GCLocker.
826 collect(cause, YoungGen);
827 } else {
828 #ifdef ASSERT
829 if (cause == GCCause::_scavenge_alot) {
830 // Young collection only.
831 collect(cause, YoungGen);
832 } else {
833 // Stop-the-world full collection.
834 collect(cause, OldGen);
835 }
836 #else
837 // Stop-the-world full collection.
838 collect(cause, OldGen);
839 #endif
840 }
841 }
842
843 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
844 // The caller doesn't have the Heap_lock
845 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
846
847 unsigned int gc_count_before;
848 unsigned int full_gc_count_before;
849
850 {
851 MutexLocker ml(Heap_lock);
852 // Read the GC count while holding the Heap_lock
853 gc_count_before = total_collections();
854 full_gc_count_before = total_full_collections();
855 }
856
857 if (GCLocker::should_discard(cause, gc_count_before)) {
858 return;
859 }
860
861 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
862 cause, max_generation);
863 VMThread::execute(&op);
864 }
865
866 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
867 do_full_collection(clear_all_soft_refs, OldGen);
868 }
869
870 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
871 GenerationType last_generation) {
872 do_collection(true, // full
873 clear_all_soft_refs, // clear_all_soft_refs
874 0, // size
875 false, // is_tlab
876 last_generation); // last_generation
877 // Hack XXX FIX ME !!!
878 // A scavenge may not have been attempted, or may have
879 // been attempted and failed, because the old gen was too full
880 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
881 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
882 // This time allow the old gen to be collected as well
883 do_collection(true, // full
884 clear_all_soft_refs, // clear_all_soft_refs
885 0, // size
886 false, // is_tlab
887 OldGen); // last_generation
888 }
889 }
890
891 bool GenCollectedHeap::is_in_young(oop p) const {
892 bool result = cast_from_oop<HeapWord*>(p) < _old_gen->reserved().start();
893 assert(result == _young_gen->is_in_reserved(p),
894 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
895 return result;
896 }
897
898 bool GenCollectedHeap::requires_barriers(stackChunkOop obj) const {
899 return !is_in_young(obj);
900 }
901
902 // Returns "TRUE" iff "p" points into the committed areas of the heap.
903 bool GenCollectedHeap::is_in(const void* p) const {
904 return _young_gen->is_in(p) || _old_gen->is_in(p);
905 }
906
907 #ifdef ASSERT
908 // Don't implement this by using is_in_young(). This method is used
909 // in some cases to check that is_in_young() is correct.
910 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
911 assert(is_in_reserved(p) || p == NULL,
912 "Does not work if address is non-null and outside of the heap");
913 return p < _young_gen->reserved().end() && p != NULL;
914 }
915 #endif
916
917 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
918 _young_gen->oop_iterate(cl);
919 _old_gen->oop_iterate(cl);
920 }
921
922 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
923 _young_gen->object_iterate(cl);
924 _old_gen->object_iterate(cl);
925 }
926
927 Space* GenCollectedHeap::space_containing(const void* addr) const {
928 Space* res = _young_gen->space_containing(addr);
929 if (res != NULL) {
930 return res;
931 }
932 res = _old_gen->space_containing(addr);
933 assert(res != NULL, "Could not find containing space");
934 return res;
935 }
936
937 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
938 assert(is_in_reserved(addr), "block_start of address outside of heap");
939 if (_young_gen->is_in_reserved(addr)) {
940 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
941 return _young_gen->block_start(addr);
942 }
943
944 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
945 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
946 return _old_gen->block_start(addr);
947 }
948
949 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
950 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
951 assert(block_start(addr) == addr, "addr must be a block start");
952 if (_young_gen->is_in_reserved(addr)) {
953 return _young_gen->block_is_obj(addr);
954 }
955
956 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
957 return _old_gen->block_is_obj(addr);
958 }
959
960 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
961 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
962 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
963 return _young_gen->tlab_capacity();
964 }
965
966 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
967 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
968 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
969 return _young_gen->tlab_used();
970 }
971
972 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
973 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
974 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
975 return _young_gen->unsafe_max_tlab_alloc();
976 }
977
978 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
979 size_t requested_size,
980 size_t* actual_size) {
981 bool gc_overhead_limit_was_exceeded;
982 HeapWord* result = mem_allocate_work(requested_size /* size */,
983 true /* is_tlab */,
984 &gc_overhead_limit_was_exceeded);
985 if (result != NULL) {
986 *actual_size = requested_size;
987 }
988
989 return result;
990 }
991
992 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
993 // from the list headed by "*prev_ptr".
994 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
995 bool first = true;
996 size_t min_size = 0; // "first" makes this conceptually infinite.
997 ScratchBlock **smallest_ptr, *smallest;
998 ScratchBlock *cur = *prev_ptr;
999 while (cur) {
1000 assert(*prev_ptr == cur, "just checking");
1001 if (first || cur->num_words < min_size) {
1002 smallest_ptr = prev_ptr;
1003 smallest = cur;
1004 min_size = smallest->num_words;
1005 first = false;
1006 }
1007 prev_ptr = &cur->next;
1008 cur = cur->next;
1009 }
1010 smallest = *smallest_ptr;
1011 *smallest_ptr = smallest->next;
1012 return smallest;
1013 }
1014
1015 // Sort the scratch block list headed by res into decreasing size order,
1016 // and set "res" to the result.
1017 static void sort_scratch_list(ScratchBlock*& list) {
1018 ScratchBlock* sorted = NULL;
1019 ScratchBlock* unsorted = list;
1020 while (unsorted) {
1021 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1022 smallest->next = sorted;
1023 sorted = smallest;
1024 }
1025 list = sorted;
1026 }
1027
1028 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1029 size_t max_alloc_words) {
1030 ScratchBlock* res = NULL;
1031 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1032 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1033 sort_scratch_list(res);
1034 return res;
1035 }
1036
1037 void GenCollectedHeap::release_scratch() {
1038 _young_gen->reset_scratch();
1039 _old_gen->reset_scratch();
1040 }
1041
1042 void GenCollectedHeap::prepare_for_verify() {
1043 ensure_parsability(false); // no need to retire TLABs
1044 }
1045
1046 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1047 bool old_to_young) {
1048 if (old_to_young) {
1049 cl->do_generation(_old_gen);
1050 cl->do_generation(_young_gen);
1051 } else {
1052 cl->do_generation(_young_gen);
1053 cl->do_generation(_old_gen);
1054 }
1055 }
1056
1057 bool GenCollectedHeap::is_maximal_no_gc() const {
1058 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1059 }
1060
1061 void GenCollectedHeap::save_marks() {
1062 _young_gen->save_marks();
1063 _old_gen->save_marks();
1064 }
1065
1066 GenCollectedHeap* GenCollectedHeap::heap() {
1067 // SerialHeap is the only subtype of GenCollectedHeap.
1068 return named_heap<GenCollectedHeap>(CollectedHeap::Serial);
1069 }
1070
1071 #if INCLUDE_SERIALGC
1072 void GenCollectedHeap::prepare_for_compaction() {
1073 // Start by compacting into same gen.
1074 CompactPoint cp(_old_gen);
1075 _forwarding->clear();
1076 _old_gen->prepare_for_compaction(&cp);
1077 _young_gen->prepare_for_compaction(&cp);
1078 }
1079 #endif // INCLUDE_SERIALGC
1080
1081 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1082 log_debug(gc, verify)("%s", _old_gen->name());
1083 _old_gen->verify();
1084
1085 log_debug(gc, verify)("%s", _old_gen->name());
1086 _young_gen->verify();
1087
1088 log_debug(gc, verify)("RemSet");
1089 rem_set()->verify();
1090 }
1091
1092 void GenCollectedHeap::print_on(outputStream* st) const {
1093 if (_young_gen != NULL) {
1094 _young_gen->print_on(st);
1095 }
1096 if (_old_gen != NULL) {
1097 _old_gen->print_on(st);
1098 }
1099 MetaspaceUtils::print_on(st);
1100 }
1101
1102 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1103 }
1104
1105 bool GenCollectedHeap::print_location(outputStream* st, void* addr) const {
1106 return BlockLocationPrinter<GenCollectedHeap>::print_location(st, addr);
1107 }
1108
1109 void GenCollectedHeap::print_tracing_info() const {
1110 if (log_is_enabled(Debug, gc, heap, exit)) {
1111 LogStreamHandle(Debug, gc, heap, exit) lsh;
1112 _young_gen->print_summary_info_on(&lsh);
1113 _old_gen->print_summary_info_on(&lsh);
1114 }
1115 }
1116
1117 void GenCollectedHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
1118 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
1119
1120 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
1121 HEAP_CHANGE_FORMAT" "
1122 HEAP_CHANGE_FORMAT,
1123 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
1124 pre_gc_values.young_gen_used(),
1125 pre_gc_values.young_gen_capacity(),
1126 def_new_gen->used(),
1127 def_new_gen->capacity()),
1128 HEAP_CHANGE_FORMAT_ARGS("Eden",
1129 pre_gc_values.eden_used(),
1130 pre_gc_values.eden_capacity(),
1131 def_new_gen->eden()->used(),
1132 def_new_gen->eden()->capacity()),
1133 HEAP_CHANGE_FORMAT_ARGS("From",
1134 pre_gc_values.from_used(),
1135 pre_gc_values.from_capacity(),
1136 def_new_gen->from()->used(),
1137 def_new_gen->from()->capacity()));
1138 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
1139 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
1140 pre_gc_values.old_gen_used(),
1141 pre_gc_values.old_gen_capacity(),
1142 old_gen()->used(),
1143 old_gen()->capacity()));
1144 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1145 }
1146
1147 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1148 private:
1149 bool _full;
1150 public:
1151 void do_generation(Generation* gen) {
1152 gen->gc_prologue(_full);
1153 }
1154 GenGCPrologueClosure(bool full) : _full(full) {};
1155 };
1156
1157 void GenCollectedHeap::gc_prologue(bool full) {
1158 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1159
1160 // Fill TLAB's and such
1161 ensure_parsability(true); // retire TLABs
1162
1163 // Walk generations
1164 GenGCPrologueClosure blk(full);
1165 generation_iterate(&blk, false); // not old-to-young.
1166 };
1167
1168 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1169 private:
1170 bool _full;
1171 public:
1172 void do_generation(Generation* gen) {
1173 gen->gc_epilogue(_full);
1174 }
1175 GenGCEpilogueClosure(bool full) : _full(full) {};
1176 };
1177
1178 void GenCollectedHeap::gc_epilogue(bool full) {
1179 #if COMPILER2_OR_JVMCI
1180 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1181 #endif // COMPILER2_OR_JVMCI
1182
1183 resize_all_tlabs();
1184
1185 GenGCEpilogueClosure blk(full);
1186 generation_iterate(&blk, false); // not old-to-young.
1187
1188 MetaspaceCounters::update_performance_counters();
1189 };
1190
1191 #ifndef PRODUCT
1192 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1193 private:
1194 public:
1195 void do_generation(Generation* gen) {
1196 gen->record_spaces_top();
1197 }
1198 };
1199
1200 void GenCollectedHeap::record_gen_tops_before_GC() {
1201 if (ZapUnusedHeapArea) {
1202 GenGCSaveTopsBeforeGCClosure blk;
1203 generation_iterate(&blk, false); // not old-to-young.
1204 }
1205 }
1206 #endif // not PRODUCT
1207
1208 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1209 public:
1210 void do_generation(Generation* gen) {
1211 gen->ensure_parsability();
1212 }
1213 };
1214
1215 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1216 CollectedHeap::ensure_parsability(retire_tlabs);
1217 GenEnsureParsabilityClosure ep_cl;
1218 generation_iterate(&ep_cl, false);
1219 }