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/gcId.hpp"
40 #include "gc/shared/gcLocker.hpp"
41 #include "gc/shared/gcPolicyCounters.hpp"
42 #include "gc/shared/gcTrace.hpp"
43 #include "gc/shared/gcTraceTime.inline.hpp"
44 #include "gc/shared/genArguments.hpp"
45 #include "gc/shared/gcVMOperations.hpp"
46 #include "gc/shared/genCollectedHeap.hpp"
47 #include "gc/shared/genOopClosures.inline.hpp"
48 #include "gc/shared/generationSpec.hpp"
49 #include "gc/shared/gcInitLogger.hpp"
50 #include "gc/shared/locationPrinter.inline.hpp"
51 #include "gc/shared/oopStorage.inline.hpp"
52 #include "gc/shared/oopStorageSet.inline.hpp"
53 #include "gc/shared/oopStorageParState.inline.hpp"
54 #include "gc/shared/scavengableNMethods.hpp"
55 #include "gc/shared/slidingForwarding.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/handles.hpp"
67 #include "runtime/handles.inline.hpp"
68 #include "runtime/java.hpp"
69 #include "runtime/vmThread.hpp"
70 #include "services/memoryService.hpp"
71 #include "utilities/autoRestore.hpp"
72 #include "utilities/debug.hpp"
73 #include "utilities/formatBuffer.hpp"
74 #include "utilities/macros.hpp"
75 #include "utilities/stack.inline.hpp"
76 #include "utilities/vmError.hpp"
77 #if INCLUDE_JVMCI
78 #include "jvmci/jvmci.hpp"
79 #endif
80
81 GenCollectedHeap::GenCollectedHeap(Generation::Name young,
82 Generation::Name old,
83 const char* policy_counters_name) :
84 CollectedHeap(),
85 _young_gen(NULL),
86 _old_gen(NULL),
87 _young_gen_spec(new GenerationSpec(young,
88 NewSize,
89 MaxNewSize,
90 GenAlignment)),
91 _old_gen_spec(new GenerationSpec(old,
92 OldSize,
93 MaxOldSize,
94 GenAlignment)),
95 _rem_set(NULL),
96 _soft_ref_gen_policy(),
97 _size_policy(NULL),
98 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
99 _incremental_collection_failed(false),
100 _full_collections_completed(0),
101 _young_manager(NULL),
102 _old_manager(NULL) {
103 }
104
105 jint GenCollectedHeap::initialize() {
106 // While there are no constraints in the GC code that HeapWordSize
107 // be any particular value, there are multiple other areas in the
108 // system which believe this to be true (e.g. oop->object_size in some
109 // cases incorrectly returns the size in wordSize units rather than
110 // HeapWordSize).
111 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
112
113 // Allocate space for the heap.
114
115 ReservedHeapSpace heap_rs = allocate(HeapAlignment);
116
117 if (!heap_rs.is_reserved()) {
118 vm_shutdown_during_initialization(
119 "Could not reserve enough space for object heap");
120 return JNI_ENOMEM;
121 }
122
123 initialize_reserved_region(heap_rs);
124 _forwarding = new SlidingForwarding(_reserved);
125
126 _rem_set = create_rem_set(heap_rs.region());
127 _rem_set->initialize();
128 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
129 bs->initialize();
130 BarrierSet::set_barrier_set(bs);
131
132 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size());
133 _young_gen = _young_gen_spec->init(young_rs, rem_set());
134 ReservedSpace old_rs = heap_rs.last_part(_young_gen_spec->max_size());
135
136 old_rs = old_rs.first_part(_old_gen_spec->max_size());
137 _old_gen = _old_gen_spec->init(old_rs, rem_set());
138
139 GCInitLogger::print();
140
141 return JNI_OK;
142 }
143
144 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
145 return new CardTableRS(reserved_region);
146 }
147
148 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
149 size_t init_promo_size,
150 size_t init_survivor_size) {
151 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
152 _size_policy = new AdaptiveSizePolicy(init_eden_size,
153 init_promo_size,
154 init_survivor_size,
155 max_gc_pause_sec,
156 GCTimeRatio);
157 }
158
159 ReservedHeapSpace GenCollectedHeap::allocate(size_t alignment) {
160 // Now figure out the total size.
161 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
162 assert(alignment % pageSize == 0, "Must be");
163
164 // Check for overflow.
165 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
166 if (total_reserved < _young_gen_spec->max_size()) {
167 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
168 "the maximum representable size");
169 }
170 assert(total_reserved % alignment == 0,
171 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
172 SIZE_FORMAT, total_reserved, alignment);
173
174 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
175 size_t used_page_size = heap_rs.page_size();
176
177 os::trace_page_sizes("Heap",
178 MinHeapSize,
179 total_reserved,
180 used_page_size,
181 heap_rs.base(),
182 heap_rs.size());
183
184 return heap_rs;
185 }
186
187 class GenIsScavengable : public BoolObjectClosure {
188 public:
189 bool do_object_b(oop obj) {
190 return GenCollectedHeap::heap()->is_in_young(obj);
191 }
192 };
193
194 static GenIsScavengable _is_scavengable;
195
196 void GenCollectedHeap::post_initialize() {
197 CollectedHeap::post_initialize();
198 ref_processing_init();
199
200 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
201
202 initialize_size_policy(def_new_gen->eden()->capacity(),
203 _old_gen->capacity(),
204 def_new_gen->from()->capacity());
205
206 MarkSweep::initialize();
207
208 ScavengableNMethods::initialize(&_is_scavengable);
209 }
210
211 void GenCollectedHeap::ref_processing_init() {
212 _young_gen->ref_processor_init();
213 _old_gen->ref_processor_init();
214 }
215
216 PreGenGCValues GenCollectedHeap::get_pre_gc_values() const {
217 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
218
219 return PreGenGCValues(def_new_gen->used(),
220 def_new_gen->capacity(),
221 def_new_gen->eden()->used(),
222 def_new_gen->eden()->capacity(),
223 def_new_gen->from()->used(),
224 def_new_gen->from()->capacity(),
225 old_gen()->used(),
226 old_gen()->capacity());
227 }
228
229 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
230 return _young_gen_spec;
231 }
232
233 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
234 return _old_gen_spec;
235 }
236
237 size_t GenCollectedHeap::capacity() const {
238 return _young_gen->capacity() + _old_gen->capacity();
239 }
240
241 size_t GenCollectedHeap::used() const {
242 return _young_gen->used() + _old_gen->used();
243 }
244
245 void GenCollectedHeap::save_used_regions() {
246 _old_gen->save_used_region();
247 _young_gen->save_used_region();
248 }
249
250 size_t GenCollectedHeap::max_capacity() const {
251 return _young_gen->max_capacity() + _old_gen->max_capacity();
252 }
253
254 // Update the _full_collections_completed counter
255 // at the end of a stop-world full GC.
256 unsigned int GenCollectedHeap::update_full_collections_completed() {
257 assert(_full_collections_completed <= _total_full_collections,
258 "Can't complete more collections than were started");
259 _full_collections_completed = _total_full_collections;
260 return _full_collections_completed;
261 }
262
263 // Return true if any of the following is true:
264 // . the allocation won't fit into the current young gen heap
265 // . gc locker is occupied (jni critical section)
266 // . heap memory is tight -- the most recent previous collection
267 // was a full collection because a partial collection (would
268 // have) failed and is likely to fail again
269 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
270 size_t young_capacity = _young_gen->capacity_before_gc();
271 return (word_size > heap_word_size(young_capacity))
272 || GCLocker::is_active_and_needs_gc()
273 || incremental_collection_failed();
274 }
275
276 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
277 HeapWord* result = NULL;
278 if (_old_gen->should_allocate(size, is_tlab)) {
279 result = _old_gen->expand_and_allocate(size, is_tlab);
280 }
281 if (result == NULL) {
282 if (_young_gen->should_allocate(size, is_tlab)) {
283 result = _young_gen->expand_and_allocate(size, is_tlab);
284 }
285 }
286 assert(result == NULL || is_in_reserved(result), "result not in heap");
287 return result;
288 }
289
290 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
291 bool is_tlab,
292 bool* gc_overhead_limit_was_exceeded) {
293 // In general gc_overhead_limit_was_exceeded should be false so
294 // set it so here and reset it to true only if the gc time
295 // limit is being exceeded as checked below.
296 *gc_overhead_limit_was_exceeded = false;
297
298 HeapWord* result = NULL;
299
300 // Loop until the allocation is satisfied, or unsatisfied after GC.
301 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
302
303 // First allocation attempt is lock-free.
304 Generation *young = _young_gen;
305 assert(young->supports_inline_contig_alloc(),
306 "Otherwise, must do alloc within heap lock");
307 if (young->should_allocate(size, is_tlab)) {
308 result = young->par_allocate(size, is_tlab);
309 if (result != NULL) {
310 assert(is_in_reserved(result), "result not in heap");
311 return result;
312 }
313 }
314 uint gc_count_before; // Read inside the Heap_lock locked region.
315 {
316 MutexLocker ml(Heap_lock);
317 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
318 // Note that only large objects get a shot at being
319 // allocated in later generations.
320 bool first_only = !should_try_older_generation_allocation(size);
321
322 result = attempt_allocation(size, is_tlab, first_only);
323 if (result != NULL) {
324 assert(is_in_reserved(result), "result not in heap");
325 return result;
326 }
327
328 if (GCLocker::is_active_and_needs_gc()) {
329 if (is_tlab) {
330 return NULL; // Caller will retry allocating individual object.
331 }
332 if (!is_maximal_no_gc()) {
333 // Try and expand heap to satisfy request.
334 result = expand_heap_and_allocate(size, is_tlab);
335 // Result could be null if we are out of space.
336 if (result != NULL) {
337 return result;
338 }
339 }
340
341 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
342 return NULL; // We didn't get to do a GC and we didn't get any memory.
343 }
344
345 // If this thread is not in a jni critical section, we stall
346 // the requestor until the critical section has cleared and
347 // GC allowed. When the critical section clears, a GC is
348 // initiated by the last thread exiting the critical section; so
349 // we retry the allocation sequence from the beginning of the loop,
350 // rather than causing more, now probably unnecessary, GC attempts.
351 JavaThread* jthr = JavaThread::current();
352 if (!jthr->in_critical()) {
353 MutexUnlocker mul(Heap_lock);
354 // Wait for JNI critical section to be exited
355 GCLocker::stall_until_clear();
356 gclocker_stalled_count += 1;
357 continue;
358 } else {
359 if (CheckJNICalls) {
360 fatal("Possible deadlock due to allocating while"
361 " in jni critical section");
362 }
363 return NULL;
364 }
365 }
366
367 // Read the gc count while the heap lock is held.
368 gc_count_before = total_collections();
369 }
370
371 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
372 VMThread::execute(&op);
373 if (op.prologue_succeeded()) {
374 result = op.result();
375 if (op.gc_locked()) {
376 assert(result == NULL, "must be NULL if gc_locked() is true");
377 continue; // Retry and/or stall as necessary.
378 }
379
380 // Allocation has failed and a collection
381 // has been done. If the gc time limit was exceeded the
382 // this time, return NULL so that an out-of-memory
383 // will be thrown. Clear gc_overhead_limit_exceeded
384 // so that the overhead exceeded does not persist.
385
386 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
387 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
388
389 if (limit_exceeded && softrefs_clear) {
390 *gc_overhead_limit_was_exceeded = true;
391 size_policy()->set_gc_overhead_limit_exceeded(false);
392 if (op.result() != NULL) {
393 CollectedHeap::fill_with_object(op.result(), size);
394 }
395 return NULL;
396 }
397 assert(result == NULL || is_in_reserved(result),
398 "result not in heap");
399 return result;
400 }
401
402 // Give a warning if we seem to be looping forever.
403 if ((QueuedAllocationWarningCount > 0) &&
404 (try_count % QueuedAllocationWarningCount == 0)) {
405 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
406 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
407 }
408 }
409 }
410
411 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
412 bool is_tlab,
413 bool first_only) {
414 HeapWord* res = NULL;
415
416 if (_young_gen->should_allocate(size, is_tlab)) {
417 res = _young_gen->allocate(size, is_tlab);
418 if (res != NULL || first_only) {
419 return res;
420 }
421 }
422
423 if (_old_gen->should_allocate(size, is_tlab)) {
424 res = _old_gen->allocate(size, is_tlab);
425 }
426
427 return res;
428 }
429
430 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
431 bool* gc_overhead_limit_was_exceeded) {
432 return mem_allocate_work(size,
433 false /* is_tlab */,
434 gc_overhead_limit_was_exceeded);
435 }
436
437 bool GenCollectedHeap::must_clear_all_soft_refs() {
438 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
439 _gc_cause == GCCause::_wb_full_gc;
440 }
441
442 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
443 bool is_tlab, bool run_verification, bool clear_soft_refs) {
444 FormatBuffer<> title("Collect gen: %s", gen->short_name());
445 GCTraceTime(Trace, gc, phases) t1(title);
446 TraceCollectorStats tcs(gen->counters());
447 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
448
449 gen->stat_record()->invocations++;
450 gen->stat_record()->accumulated_time.start();
451
452 // Must be done anew before each collection because
453 // a previous collection will do mangling and will
454 // change top of some spaces.
455 record_gen_tops_before_GC();
456
457 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
458
459 if (run_verification && VerifyBeforeGC) {
460 Universe::verify("Before GC");
461 }
462 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
463
464 // Do collection work
465 {
466 // Note on ref discovery: For what appear to be historical reasons,
467 // GCH enables and disabled (by enqueuing) refs discovery.
468 // In the future this should be moved into the generation's
469 // collect method so that ref discovery and enqueueing concerns
470 // are local to a generation. The collect method could return
471 // an appropriate indication in the case that notification on
472 // the ref lock was needed. This will make the treatment of
473 // weak refs more uniform (and indeed remove such concerns
474 // from GCH). XXX
475
476 save_marks(); // save marks for all gens
477 // We want to discover references, but not process them yet.
478 // This mode is disabled in process_discovered_references if the
479 // generation does some collection work, or in
480 // enqueue_discovered_references if the generation returns
481 // without doing any work.
482 ReferenceProcessor* rp = gen->ref_processor();
483 rp->start_discovery(clear_soft_refs);
484
485 gen->collect(full, clear_soft_refs, size, is_tlab);
486
487 rp->disable_discovery();
488 rp->verify_no_references_recorded();
489 }
490
491 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
492
493 gen->stat_record()->accumulated_time.stop();
494
495 update_gc_stats(gen, full);
496
497 if (run_verification && VerifyAfterGC) {
498 Universe::verify("After GC");
499 }
500 }
501
502 void GenCollectedHeap::do_collection(bool full,
503 bool clear_all_soft_refs,
504 size_t size,
505 bool is_tlab,
506 GenerationType max_generation) {
507 ResourceMark rm;
508 DEBUG_ONLY(Thread* my_thread = Thread::current();)
509
510 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
511 assert(my_thread->is_VM_thread(), "only VM thread");
512 assert(Heap_lock->is_locked(),
513 "the requesting thread should have the Heap_lock");
514 guarantee(!is_gc_active(), "collection is not reentrant");
515
516 if (GCLocker::check_active_before_gc()) {
517 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
518 }
519
520 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
521 soft_ref_policy()->should_clear_all_soft_refs();
522
523 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
524
525 AutoModifyRestore<bool> temporarily(_is_gc_active, true);
526
527 bool complete = full && (max_generation == OldGen);
528 bool old_collects_young = complete && !ScavengeBeforeFullGC;
529 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
530
531 const PreGenGCValues pre_gc_values = get_pre_gc_values();
532
533 bool run_verification = total_collections() >= VerifyGCStartAt;
534 bool prepared_for_verification = false;
535 bool do_full_collection = false;
536
537 if (do_young_collection) {
538 GCIdMark gc_id_mark;
539 GCTraceCPUTime tcpu;
540 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
541
542 print_heap_before_gc();
543
544 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
545 prepare_for_verify();
546 prepared_for_verification = true;
547 }
548
549 gc_prologue(complete);
550 increment_total_collections(complete);
551
552 collect_generation(_young_gen,
553 full,
554 size,
555 is_tlab,
556 run_verification && VerifyGCLevel <= 0,
557 do_clear_all_soft_refs);
558
559 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
560 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
561 // Allocation request was met by young GC.
562 size = 0;
563 }
564
565 // Ask if young collection is enough. If so, do the final steps for young collection,
566 // and fallthrough to the end.
567 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
568 if (!do_full_collection) {
569 // Adjust generation sizes.
570 _young_gen->compute_new_size();
571
572 print_heap_change(pre_gc_values);
573
574 // Track memory usage and detect low memory after GC finishes
575 MemoryService::track_memory_usage();
576
577 gc_epilogue(complete);
578 }
579
580 print_heap_after_gc();
581
582 } else {
583 // No young collection, ask if we need to perform Full collection.
584 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
585 }
586
587 if (do_full_collection) {
588 GCIdMark gc_id_mark;
589 GCTraceCPUTime tcpu;
590 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
591
592 print_heap_before_gc();
593
594 if (!prepared_for_verification && run_verification &&
595 VerifyGCLevel <= 1 && VerifyBeforeGC) {
596 prepare_for_verify();
597 }
598
599 if (!do_young_collection) {
600 gc_prologue(complete);
601 increment_total_collections(complete);
602 }
603
604 // Accounting quirk: total full collections would be incremented when "complete"
605 // is set, by calling increment_total_collections above. However, we also need to
606 // account Full collections that had "complete" unset.
607 if (!complete) {
608 increment_total_full_collections();
609 }
610
611 collect_generation(_old_gen,
612 full,
613 size,
614 is_tlab,
615 run_verification && VerifyGCLevel <= 1,
616 do_clear_all_soft_refs);
617
618 // Adjust generation sizes.
619 _old_gen->compute_new_size();
620 _young_gen->compute_new_size();
621
622 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
623 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
624 DEBUG_ONLY(MetaspaceUtils::verify();)
625 // Resize the metaspace capacity after full collections
626 MetaspaceGC::compute_new_size();
627 update_full_collections_completed();
628
629 print_heap_change(pre_gc_values);
630
631 // Track memory usage and detect low memory after GC finishes
632 MemoryService::track_memory_usage();
633
634 // Need to tell the epilogue code we are done with Full GC, regardless what was
635 // the initial value for "complete" flag.
636 gc_epilogue(true);
637
638 print_heap_after_gc();
639 }
640 }
641
642 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
643 GenCollectedHeap::GenerationType max_gen) const {
644 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
645 }
646
647 void GenCollectedHeap::register_nmethod(nmethod* nm) {
648 ScavengableNMethods::register_nmethod(nm);
649 }
650
651 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
652 ScavengableNMethods::unregister_nmethod(nm);
653 }
654
655 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
656 ScavengableNMethods::verify_nmethod(nm);
657 }
658
659 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
660 // Do nothing.
661 }
662
663 void GenCollectedHeap::prune_scavengable_nmethods() {
664 ScavengableNMethods::prune_nmethods();
665 }
666
667 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
668 GCCauseSetter x(this, GCCause::_allocation_failure);
669 HeapWord* result = NULL;
670
671 assert(size != 0, "Precondition violated");
672 if (GCLocker::is_active_and_needs_gc()) {
673 // GC locker is active; instead of a collection we will attempt
674 // to expand the heap, if there's room for expansion.
675 if (!is_maximal_no_gc()) {
676 result = expand_heap_and_allocate(size, is_tlab);
677 }
678 return result; // Could be null if we are out of space.
679 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
680 // Do an incremental collection.
681 do_collection(false, // full
682 false, // clear_all_soft_refs
683 size, // size
684 is_tlab, // is_tlab
685 GenCollectedHeap::OldGen); // max_generation
686 } else {
687 log_trace(gc)(" :: Trying full because partial may fail :: ");
688 // Try a full collection; see delta for bug id 6266275
689 // for the original code and why this has been simplified
690 // with from-space allocation criteria modified and
691 // such allocation moved out of the safepoint path.
692 do_collection(true, // full
693 false, // clear_all_soft_refs
694 size, // size
695 is_tlab, // is_tlab
696 GenCollectedHeap::OldGen); // max_generation
697 }
698
699 result = attempt_allocation(size, is_tlab, false /*first_only*/);
700
701 if (result != NULL) {
702 assert(is_in_reserved(result), "result not in heap");
703 return result;
704 }
705
706 // OK, collection failed, try expansion.
707 result = expand_heap_and_allocate(size, is_tlab);
708 if (result != NULL) {
709 return result;
710 }
711
712 // If we reach this point, we're really out of memory. Try every trick
713 // we can to reclaim memory. Force collection of soft references. Force
714 // a complete compaction of the heap. Any additional methods for finding
715 // free memory should be here, especially if they are expensive. If this
716 // attempt fails, an OOM exception will be thrown.
717 {
718 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
719
720 do_collection(true, // full
721 true, // clear_all_soft_refs
722 size, // size
723 is_tlab, // is_tlab
724 GenCollectedHeap::OldGen); // max_generation
725 }
726
727 result = attempt_allocation(size, is_tlab, false /* first_only */);
728 if (result != NULL) {
729 assert(is_in_reserved(result), "result not in heap");
730 return result;
731 }
732
733 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
734 "Flag should have been handled and cleared prior to this point");
735
736 // What else? We might try synchronous finalization later. If the total
737 // space available is large enough for the allocation, then a more
738 // complete compaction phase than we've tried so far might be
739 // appropriate.
740 return NULL;
741 }
742
743 #ifdef ASSERT
744 class AssertNonScavengableClosure: public OopClosure {
745 public:
746 virtual void do_oop(oop* p) {
747 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
748 "Referent should not be scavengable."); }
749 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
750 };
751 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
752 #endif
753
754 void GenCollectedHeap::process_roots(ScanningOption so,
755 OopClosure* strong_roots,
756 CLDClosure* strong_cld_closure,
757 CLDClosure* weak_cld_closure,
758 CodeBlobToOopClosure* code_roots) {
759 // General roots.
760 assert(code_roots != NULL, "code root closure should always be set");
761
762 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
763
764 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
765 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
766
767 Threads::oops_do(strong_roots, roots_from_code_p);
768
769 OopStorageSet::strong_oops_do(strong_roots);
770
771 if (so & SO_ScavengeCodeCache) {
772 assert(code_roots != NULL, "must supply closure for code cache");
773
774 // We only visit parts of the CodeCache when scavenging.
775 ScavengableNMethods::nmethods_do(code_roots);
776 }
777 if (so & SO_AllCodeCache) {
778 assert(code_roots != NULL, "must supply closure for code cache");
779
780 // CMSCollector uses this to do intermediate-strength collections.
781 // We scan the entire code cache, since CodeCache::do_unloading is not called.
782 CodeCache::blobs_do(code_roots);
783 }
784 // Verify that the code cache contents are not subject to
785 // movement by a scavenging collection.
786 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
787 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
788 }
789
790 void GenCollectedHeap::full_process_roots(bool is_adjust_phase,
791 ScanningOption so,
792 bool only_strong_roots,
793 OopClosure* root_closure,
794 CLDClosure* cld_closure) {
795 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
796 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
797
798 process_roots(so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
799 }
800
801 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
802 WeakProcessor::oops_do(root_closure);
803 }
804
805 bool GenCollectedHeap::no_allocs_since_save_marks() {
806 return _young_gen->no_allocs_since_save_marks() &&
807 _old_gen->no_allocs_since_save_marks();
808 }
809
810 bool GenCollectedHeap::supports_inline_contig_alloc() const {
811 return _young_gen->supports_inline_contig_alloc();
812 }
813
814 HeapWord* volatile* GenCollectedHeap::top_addr() const {
815 return _young_gen->top_addr();
816 }
817
818 HeapWord** GenCollectedHeap::end_addr() const {
819 return _young_gen->end_addr();
820 }
821
822 // public collection interfaces
823
824 void GenCollectedHeap::collect(GCCause::Cause cause) {
825 if ((cause == GCCause::_wb_young_gc) ||
826 (cause == GCCause::_gc_locker)) {
827 // Young collection for WhiteBox or GCLocker.
828 collect(cause, YoungGen);
829 } else {
830 #ifdef ASSERT
831 if (cause == GCCause::_scavenge_alot) {
832 // Young collection only.
833 collect(cause, YoungGen);
834 } else {
835 // Stop-the-world full collection.
836 collect(cause, OldGen);
837 }
838 #else
839 // Stop-the-world full collection.
840 collect(cause, OldGen);
841 #endif
842 }
843 }
844
845 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
846 // The caller doesn't have the Heap_lock
847 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
848
849 unsigned int gc_count_before;
850 unsigned int full_gc_count_before;
851
852 {
853 MutexLocker ml(Heap_lock);
854 // Read the GC count while holding the Heap_lock
855 gc_count_before = total_collections();
856 full_gc_count_before = total_full_collections();
857 }
858
859 if (GCLocker::should_discard(cause, gc_count_before)) {
860 return;
861 }
862
863 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
864 cause, max_generation);
865 VMThread::execute(&op);
866 }
867
868 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
869 do_full_collection(clear_all_soft_refs, OldGen);
870 }
871
872 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
873 GenerationType last_generation) {
874 do_collection(true, // full
875 clear_all_soft_refs, // clear_all_soft_refs
876 0, // size
877 false, // is_tlab
878 last_generation); // last_generation
879 // Hack XXX FIX ME !!!
880 // A scavenge may not have been attempted, or may have
881 // been attempted and failed, because the old gen was too full
882 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
883 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
884 // This time allow the old gen to be collected as well
885 do_collection(true, // full
886 clear_all_soft_refs, // clear_all_soft_refs
887 0, // size
888 false, // is_tlab
889 OldGen); // last_generation
890 }
891 }
892
893 bool GenCollectedHeap::is_in_young(oop p) {
894 bool result = cast_from_oop<HeapWord*>(p) < _old_gen->reserved().start();
895 assert(result == _young_gen->is_in_reserved(p),
896 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
897 return result;
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 _forwarding->clear();
1074 _old_gen->prepare_for_compaction(&cp);
1075 _young_gen->prepare_for_compaction(&cp);
1076 }
1077 #endif // INCLUDE_SERIALGC
1078
1079 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1080 log_debug(gc, verify)("%s", _old_gen->name());
1081 _old_gen->verify();
1082
1083 log_debug(gc, verify)("%s", _old_gen->name());
1084 _young_gen->verify();
1085
1086 log_debug(gc, verify)("RemSet");
1087 rem_set()->verify();
1088 }
1089
1090 void GenCollectedHeap::print_on(outputStream* st) const {
1091 if (_young_gen != NULL) {
1092 _young_gen->print_on(st);
1093 }
1094 if (_old_gen != NULL) {
1095 _old_gen->print_on(st);
1096 }
1097 MetaspaceUtils::print_on(st);
1098 }
1099
1100 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1101 }
1102
1103 bool GenCollectedHeap::print_location(outputStream* st, void* addr) const {
1104 return BlockLocationPrinter<GenCollectedHeap>::print_location(st, addr);
1105 }
1106
1107 void GenCollectedHeap::print_tracing_info() const {
1108 if (log_is_enabled(Debug, gc, heap, exit)) {
1109 LogStreamHandle(Debug, gc, heap, exit) lsh;
1110 _young_gen->print_summary_info_on(&lsh);
1111 _old_gen->print_summary_info_on(&lsh);
1112 }
1113 }
1114
1115 void GenCollectedHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
1116 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
1117
1118 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
1119 HEAP_CHANGE_FORMAT" "
1120 HEAP_CHANGE_FORMAT,
1121 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
1122 pre_gc_values.young_gen_used(),
1123 pre_gc_values.young_gen_capacity(),
1124 def_new_gen->used(),
1125 def_new_gen->capacity()),
1126 HEAP_CHANGE_FORMAT_ARGS("Eden",
1127 pre_gc_values.eden_used(),
1128 pre_gc_values.eden_capacity(),
1129 def_new_gen->eden()->used(),
1130 def_new_gen->eden()->capacity()),
1131 HEAP_CHANGE_FORMAT_ARGS("From",
1132 pre_gc_values.from_used(),
1133 pre_gc_values.from_capacity(),
1134 def_new_gen->from()->used(),
1135 def_new_gen->from()->capacity()));
1136 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
1137 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
1138 pre_gc_values.old_gen_used(),
1139 pre_gc_values.old_gen_capacity(),
1140 old_gen()->used(),
1141 old_gen()->capacity()));
1142 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1143 }
1144
1145 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1146 private:
1147 bool _full;
1148 public:
1149 void do_generation(Generation* gen) {
1150 gen->gc_prologue(_full);
1151 }
1152 GenGCPrologueClosure(bool full) : _full(full) {};
1153 };
1154
1155 void GenCollectedHeap::gc_prologue(bool full) {
1156 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1157
1158 // Fill TLAB's and such
1159 ensure_parsability(true); // retire TLABs
1160
1161 // Walk generations
1162 GenGCPrologueClosure blk(full);
1163 generation_iterate(&blk, false); // not old-to-young.
1164 };
1165
1166 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1167 private:
1168 bool _full;
1169 public:
1170 void do_generation(Generation* gen) {
1171 gen->gc_epilogue(_full);
1172 }
1173 GenGCEpilogueClosure(bool full) : _full(full) {};
1174 };
1175
1176 void GenCollectedHeap::gc_epilogue(bool full) {
1177 #if COMPILER2_OR_JVMCI
1178 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1179 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1180 guarantee(!CompilerConfig::is_c2_or_jvmci_compiler_enabled() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
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 }
1220
1221 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1222 oop obj,
1223 size_t obj_size) {
1224 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1225 assert(obj_size == obj->size(), "bad obj_size passed in");
1226 HeapWord* result = NULL;
1227
1228 result = old_gen->expand_and_allocate(obj_size, false);
1229
1230 if (result != NULL) {
1231 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), result, obj_size);
1232 }
1233 return cast_to_oop(result);
1234 }