1 /*
2 * Copyright (c) 2000, 2021, 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/space.hpp"
56 #include "gc/shared/strongRootsScope.hpp"
57 #include "gc/shared/weakProcessor.hpp"
58 #include "gc/shared/workerThread.hpp"
59 #include "memory/iterator.hpp"
60 #include "memory/metaspaceCounters.hpp"
61 #include "memory/metaspaceUtils.hpp"
62 #include "memory/resourceArea.hpp"
63 #include "memory/universe.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "runtime/handles.hpp"
66 #include "runtime/handles.inline.hpp"
67 #include "runtime/java.hpp"
68 #include "runtime/vmThread.hpp"
69 #include "services/memoryService.hpp"
70 #include "utilities/autoRestore.hpp"
71 #include "utilities/debug.hpp"
72 #include "utilities/formatBuffer.hpp"
73 #include "utilities/macros.hpp"
74 #include "utilities/stack.inline.hpp"
75 #include "utilities/vmError.hpp"
76 #if INCLUDE_JVMCI
77 #include "jvmci/jvmci.hpp"
78 #endif
79
80 GenCollectedHeap::GenCollectedHeap(Generation::Name young,
81 Generation::Name old,
82 const char* policy_counters_name) :
83 CollectedHeap(),
84 _young_gen(NULL),
85 _old_gen(NULL),
86 _young_gen_spec(new GenerationSpec(young,
87 NewSize,
88 MaxNewSize,
89 GenAlignment)),
90 _old_gen_spec(new GenerationSpec(old,
91 OldSize,
92 MaxOldSize,
93 GenAlignment)),
94 _rem_set(NULL),
95 _soft_ref_gen_policy(),
96 _size_policy(NULL),
97 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
98 _incremental_collection_failed(false),
99 _full_collections_completed(0),
100 _young_manager(NULL),
101 _old_manager(NULL) {
102 }
103
104 jint GenCollectedHeap::initialize() {
105 // While there are no constraints in the GC code that HeapWordSize
106 // be any particular value, there are multiple other areas in the
107 // system which believe this to be true (e.g. oop->object_size in some
108 // cases incorrectly returns the size in wordSize units rather than
109 // HeapWordSize).
110 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
111
112 // Allocate space for the heap.
113
114 ReservedHeapSpace heap_rs = allocate(HeapAlignment);
115
116 if (!heap_rs.is_reserved()) {
117 vm_shutdown_during_initialization(
118 "Could not reserve enough space for object heap");
119 return JNI_ENOMEM;
120 }
121
122 initialize_reserved_region(heap_rs);
123
124 _rem_set = create_rem_set(heap_rs.region());
125 _rem_set->initialize();
126 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
127 bs->initialize();
128 BarrierSet::set_barrier_set(bs);
129
130 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size());
131 _young_gen = _young_gen_spec->init(young_rs, rem_set());
132 ReservedSpace old_rs = heap_rs.last_part(_young_gen_spec->max_size());
133
134 old_rs = old_rs.first_part(_old_gen_spec->max_size());
135 _old_gen = _old_gen_spec->init(old_rs, rem_set());
136
137 GCInitLogger::print();
138
139 return JNI_OK;
140 }
141
142 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
143 return new CardTableRS(reserved_region);
144 }
145
146 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
147 size_t init_promo_size,
148 size_t init_survivor_size) {
149 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
150 _size_policy = new AdaptiveSizePolicy(init_eden_size,
151 init_promo_size,
152 init_survivor_size,
153 max_gc_pause_sec,
154 GCTimeRatio);
155 }
156
157 ReservedHeapSpace GenCollectedHeap::allocate(size_t alignment) {
158 // Now figure out the total size.
159 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
160 assert(alignment % pageSize == 0, "Must be");
161
162 // Check for overflow.
163 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
164 if (total_reserved < _young_gen_spec->max_size()) {
165 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
166 "the maximum representable size");
167 }
168 assert(total_reserved % alignment == 0,
169 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
170 SIZE_FORMAT, total_reserved, alignment);
171
172 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
173 size_t used_page_size = heap_rs.page_size();
174
175 os::trace_page_sizes("Heap",
176 MinHeapSize,
177 total_reserved,
178 used_page_size,
179 heap_rs.base(),
180 heap_rs.size());
181
182 return heap_rs;
183 }
184
185 class GenIsScavengable : public BoolObjectClosure {
186 public:
187 bool do_object_b(oop obj) {
188 return GenCollectedHeap::heap()->is_in_young(obj);
189 }
190 };
191
192 static GenIsScavengable _is_scavengable;
193
194 void GenCollectedHeap::post_initialize() {
195 CollectedHeap::post_initialize();
196 ref_processing_init();
197
198 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
199
200 initialize_size_policy(def_new_gen->eden()->capacity(),
201 _old_gen->capacity(),
202 def_new_gen->from()->capacity());
203
204 MarkSweep::initialize();
205
206 ScavengableNMethods::initialize(&_is_scavengable);
207 }
208
209 void GenCollectedHeap::ref_processing_init() {
210 _young_gen->ref_processor_init();
211 _old_gen->ref_processor_init();
212 }
213
214 PreGenGCValues GenCollectedHeap::get_pre_gc_values() const {
215 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
216
217 return PreGenGCValues(def_new_gen->used(),
218 def_new_gen->capacity(),
219 def_new_gen->eden()->used(),
220 def_new_gen->eden()->capacity(),
221 def_new_gen->from()->used(),
222 def_new_gen->from()->capacity(),
223 old_gen()->used(),
224 old_gen()->capacity());
225 }
226
227 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
228 return _young_gen_spec;
229 }
230
231 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
232 return _old_gen_spec;
233 }
234
235 size_t GenCollectedHeap::capacity() const {
236 return _young_gen->capacity() + _old_gen->capacity();
237 }
238
239 size_t GenCollectedHeap::used() const {
240 return _young_gen->used() + _old_gen->used();
241 }
242
243 void GenCollectedHeap::save_used_regions() {
244 _old_gen->save_used_region();
245 _young_gen->save_used_region();
246 }
247
248 size_t GenCollectedHeap::max_capacity() const {
249 return _young_gen->max_capacity() + _old_gen->max_capacity();
250 }
251
252 // Update the _full_collections_completed counter
253 // at the end of a stop-world full GC.
254 unsigned int GenCollectedHeap::update_full_collections_completed() {
255 assert(_full_collections_completed <= _total_full_collections,
256 "Can't complete more collections than were started");
257 _full_collections_completed = _total_full_collections;
258 return _full_collections_completed;
259 }
260
261 // Return true if any of the following is true:
262 // . the allocation won't fit into the current young gen heap
263 // . gc locker is occupied (jni critical section)
264 // . heap memory is tight -- the most recent previous collection
265 // was a full collection because a partial collection (would
266 // have) failed and is likely to fail again
267 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
268 size_t young_capacity = _young_gen->capacity_before_gc();
269 return (word_size > heap_word_size(young_capacity))
270 || GCLocker::is_active_and_needs_gc()
271 || incremental_collection_failed();
272 }
273
274 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
275 HeapWord* result = NULL;
276 if (_old_gen->should_allocate(size, is_tlab)) {
277 result = _old_gen->expand_and_allocate(size, is_tlab);
278 }
279 if (result == NULL) {
280 if (_young_gen->should_allocate(size, is_tlab)) {
281 result = _young_gen->expand_and_allocate(size, is_tlab);
282 }
283 }
284 assert(result == NULL || is_in_reserved(result), "result not in heap");
285 return result;
286 }
287
288 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
289 bool is_tlab,
290 bool* gc_overhead_limit_was_exceeded) {
291 // In general gc_overhead_limit_was_exceeded should be false so
292 // set it so here and reset it to true only if the gc time
293 // limit is being exceeded as checked below.
294 *gc_overhead_limit_was_exceeded = false;
295
296 HeapWord* result = NULL;
297
298 // Loop until the allocation is satisfied, or unsatisfied after GC.
299 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
300
301 // First allocation attempt is lock-free.
302 Generation *young = _young_gen;
303 assert(young->supports_inline_contig_alloc(),
304 "Otherwise, must do alloc within heap lock");
305 if (young->should_allocate(size, is_tlab)) {
306 result = young->par_allocate(size, is_tlab);
307 if (result != NULL) {
308 assert(is_in_reserved(result), "result not in heap");
309 return result;
310 }
311 }
312 uint gc_count_before; // Read inside the Heap_lock locked region.
313 {
314 MutexLocker ml(Heap_lock);
315 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
316 // Note that only large objects get a shot at being
317 // allocated in later generations.
318 bool first_only = !should_try_older_generation_allocation(size);
319
320 result = attempt_allocation(size, is_tlab, first_only);
321 if (result != NULL) {
322 assert(is_in_reserved(result), "result not in heap");
323 return result;
324 }
325
326 if (GCLocker::is_active_and_needs_gc()) {
327 if (is_tlab) {
328 return NULL; // Caller will retry allocating individual object.
329 }
330 if (!is_maximal_no_gc()) {
331 // Try and expand heap to satisfy request.
332 result = expand_heap_and_allocate(size, is_tlab);
333 // Result could be null if we are out of space.
334 if (result != NULL) {
335 return result;
336 }
337 }
338
339 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
340 return NULL; // We didn't get to do a GC and we didn't get any memory.
341 }
342
343 // If this thread is not in a jni critical section, we stall
344 // the requestor until the critical section has cleared and
345 // GC allowed. When the critical section clears, a GC is
346 // initiated by the last thread exiting the critical section; so
347 // we retry the allocation sequence from the beginning of the loop,
348 // rather than causing more, now probably unnecessary, GC attempts.
349 JavaThread* jthr = JavaThread::current();
350 if (!jthr->in_critical()) {
351 MutexUnlocker mul(Heap_lock);
352 // Wait for JNI critical section to be exited
353 GCLocker::stall_until_clear();
354 gclocker_stalled_count += 1;
355 continue;
356 } else {
357 if (CheckJNICalls) {
358 fatal("Possible deadlock due to allocating while"
359 " in jni critical section");
360 }
361 return NULL;
362 }
363 }
364
365 // Read the gc count while the heap lock is held.
366 gc_count_before = total_collections();
367 }
368
369 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
370 VMThread::execute(&op);
371 if (op.prologue_succeeded()) {
372 result = op.result();
373 if (op.gc_locked()) {
374 assert(result == NULL, "must be NULL if gc_locked() is true");
375 continue; // Retry and/or stall as necessary.
376 }
377
378 // Allocation has failed and a collection
379 // has been done. If the gc time limit was exceeded the
380 // this time, return NULL so that an out-of-memory
381 // will be thrown. Clear gc_overhead_limit_exceeded
382 // so that the overhead exceeded does not persist.
383
384 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
385 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
386
387 if (limit_exceeded && softrefs_clear) {
388 *gc_overhead_limit_was_exceeded = true;
389 size_policy()->set_gc_overhead_limit_exceeded(false);
390 if (op.result() != NULL) {
391 CollectedHeap::fill_with_object(op.result(), size);
392 }
393 return NULL;
394 }
395 assert(result == NULL || is_in_reserved(result),
396 "result not in heap");
397 return result;
398 }
399
400 // Give a warning if we seem to be looping forever.
401 if ((QueuedAllocationWarningCount > 0) &&
402 (try_count % QueuedAllocationWarningCount == 0)) {
403 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
404 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
405 }
406 }
407 }
408
409 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
410 bool is_tlab,
411 bool first_only) {
412 HeapWord* res = NULL;
413
414 if (_young_gen->should_allocate(size, is_tlab)) {
415 res = _young_gen->allocate(size, is_tlab);
416 if (res != NULL || first_only) {
417 return res;
418 }
419 }
420
421 if (_old_gen->should_allocate(size, is_tlab)) {
422 res = _old_gen->allocate(size, is_tlab);
423 }
424
425 return res;
426 }
427
428 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
429 bool* gc_overhead_limit_was_exceeded) {
430 return mem_allocate_work(size,
431 false /* is_tlab */,
432 gc_overhead_limit_was_exceeded);
433 }
434
435 bool GenCollectedHeap::must_clear_all_soft_refs() {
436 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
437 _gc_cause == GCCause::_wb_full_gc;
438 }
439
440 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
441 bool is_tlab, bool run_verification, bool clear_soft_refs) {
442 FormatBuffer<> title("Collect gen: %s", gen->short_name());
443 GCTraceTime(Trace, gc, phases) t1(title);
444 TraceCollectorStats tcs(gen->counters());
445 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
446
447 gen->stat_record()->invocations++;
448 gen->stat_record()->accumulated_time.start();
449
450 // Must be done anew before each collection because
451 // a previous collection will do mangling and will
452 // change top of some spaces.
453 record_gen_tops_before_GC();
454
455 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
456
457 if (run_verification && VerifyBeforeGC) {
458 Universe::verify("Before GC");
459 }
460 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
461
462 // Do collection work
463 {
464 // Note on ref discovery: For what appear to be historical reasons,
465 // GCH enables and disabled (by enqueing) refs discovery.
466 // In the future this should be moved into the generation's
467 // collect method so that ref discovery and enqueueing concerns
468 // are local to a generation. The collect method could return
469 // an appropriate indication in the case that notification on
470 // the ref lock was needed. This will make the treatment of
471 // weak refs more uniform (and indeed remove such concerns
472 // from GCH). XXX
473
474 save_marks(); // save marks for all gens
475 // We want to discover references, but not process them yet.
476 // This mode is disabled in process_discovered_references if the
477 // generation does some collection work, or in
478 // enqueue_discovered_references if the generation returns
479 // without doing any work.
480 ReferenceProcessor* rp = gen->ref_processor();
481 rp->start_discovery(clear_soft_refs);
482
483 gen->collect(full, clear_soft_refs, size, is_tlab);
484
485 rp->disable_discovery();
486 rp->verify_no_references_recorded();
487 }
488
489 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
490
491 gen->stat_record()->accumulated_time.stop();
492
493 update_gc_stats(gen, full);
494
495 if (run_verification && VerifyAfterGC) {
496 Universe::verify("After GC");
497 }
498 }
499
500 void GenCollectedHeap::do_collection(bool full,
501 bool clear_all_soft_refs,
502 size_t size,
503 bool is_tlab,
504 GenerationType max_generation) {
505 ResourceMark rm;
506 DEBUG_ONLY(Thread* my_thread = Thread::current();)
507
508 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
509 assert(my_thread->is_VM_thread(), "only VM thread");
510 assert(Heap_lock->is_locked(),
511 "the requesting thread should have the Heap_lock");
512 guarantee(!is_gc_active(), "collection is not reentrant");
513
514 if (GCLocker::check_active_before_gc()) {
515 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
516 }
517
518 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
519 soft_ref_policy()->should_clear_all_soft_refs();
520
521 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
522
523 AutoModifyRestore<bool> temporarily(_is_gc_active, true);
524
525 bool complete = full && (max_generation == OldGen);
526 bool old_collects_young = complete && !ScavengeBeforeFullGC;
527 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
528
529 const PreGenGCValues pre_gc_values = get_pre_gc_values();
530
531 bool run_verification = total_collections() >= VerifyGCStartAt;
532 bool prepared_for_verification = false;
533 bool do_full_collection = false;
534
535 if (do_young_collection) {
536 GCIdMark gc_id_mark;
537 GCTraceCPUTime tcpu;
538 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
539
540 print_heap_before_gc();
541
542 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
543 prepare_for_verify();
544 prepared_for_verification = true;
545 }
546
547 gc_prologue(complete);
548 increment_total_collections(complete);
549
550 collect_generation(_young_gen,
551 full,
552 size,
553 is_tlab,
554 run_verification && VerifyGCLevel <= 0,
555 do_clear_all_soft_refs);
556
557 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
558 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
559 // Allocation request was met by young GC.
560 size = 0;
561 }
562
563 // Ask if young collection is enough. If so, do the final steps for young collection,
564 // and fallthrough to the end.
565 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
566 if (!do_full_collection) {
567 // Adjust generation sizes.
568 _young_gen->compute_new_size();
569
570 print_heap_change(pre_gc_values);
571
572 // Track memory usage and detect low memory after GC finishes
573 MemoryService::track_memory_usage();
574
575 gc_epilogue(complete);
576 }
577
578 print_heap_after_gc();
579
580 } else {
581 // No young collection, ask if we need to perform Full collection.
582 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
583 }
584
585 if (do_full_collection) {
586 GCIdMark gc_id_mark;
587 GCTraceCPUTime tcpu;
588 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
589
590 print_heap_before_gc();
591
592 if (!prepared_for_verification && run_verification &&
593 VerifyGCLevel <= 1 && VerifyBeforeGC) {
594 prepare_for_verify();
595 }
596
597 if (!do_young_collection) {
598 gc_prologue(complete);
599 increment_total_collections(complete);
600 }
601
602 // Accounting quirk: total full collections would be incremented when "complete"
603 // is set, by calling increment_total_collections above. However, we also need to
604 // account Full collections that had "complete" unset.
605 if (!complete) {
606 increment_total_full_collections();
607 }
608
609 collect_generation(_old_gen,
610 full,
611 size,
612 is_tlab,
613 run_verification && VerifyGCLevel <= 1,
614 do_clear_all_soft_refs);
615
616 // Adjust generation sizes.
617 _old_gen->compute_new_size();
618 _young_gen->compute_new_size();
619
620 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
621 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
622 DEBUG_ONLY(MetaspaceUtils::verify();)
623 // Resize the metaspace capacity after full collections
624 MetaspaceGC::compute_new_size();
625 update_full_collections_completed();
626
627 print_heap_change(pre_gc_values);
628
629 // Track memory usage and detect low memory after GC finishes
630 MemoryService::track_memory_usage();
631
632 // Need to tell the epilogue code we are done with Full GC, regardless what was
633 // the initial value for "complete" flag.
634 gc_epilogue(true);
635
636 print_heap_after_gc();
637 }
638 }
639
640 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
641 GenCollectedHeap::GenerationType max_gen) const {
642 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
643 }
644
645 void GenCollectedHeap::register_nmethod(nmethod* nm) {
646 ScavengableNMethods::register_nmethod(nm);
647 }
648
649 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
650 ScavengableNMethods::unregister_nmethod(nm);
651 }
652
653 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
654 ScavengableNMethods::verify_nmethod(nm);
655 }
656
657 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
658 // Do nothing.
659 }
660
661 void GenCollectedHeap::prune_scavengable_nmethods() {
662 ScavengableNMethods::prune_nmethods();
663 }
664
665 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
666 GCCauseSetter x(this, GCCause::_allocation_failure);
667 HeapWord* result = NULL;
668
669 assert(size != 0, "Precondition violated");
670 if (GCLocker::is_active_and_needs_gc()) {
671 // GC locker is active; instead of a collection we will attempt
672 // to expand the heap, if there's room for expansion.
673 if (!is_maximal_no_gc()) {
674 result = expand_heap_and_allocate(size, is_tlab);
675 }
676 return result; // Could be null if we are out of space.
677 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
678 // Do an incremental collection.
679 do_collection(false, // full
680 false, // clear_all_soft_refs
681 size, // size
682 is_tlab, // is_tlab
683 GenCollectedHeap::OldGen); // max_generation
684 } else {
685 log_trace(gc)(" :: Trying full because partial may fail :: ");
686 // Try a full collection; see delta for bug id 6266275
687 // for the original code and why this has been simplified
688 // with from-space allocation criteria modified and
689 // such allocation moved out of the safepoint path.
690 do_collection(true, // full
691 false, // clear_all_soft_refs
692 size, // size
693 is_tlab, // is_tlab
694 GenCollectedHeap::OldGen); // max_generation
695 }
696
697 result = attempt_allocation(size, is_tlab, false /*first_only*/);
698
699 if (result != NULL) {
700 assert(is_in_reserved(result), "result not in heap");
701 return result;
702 }
703
704 // OK, collection failed, try expansion.
705 result = expand_heap_and_allocate(size, is_tlab);
706 if (result != NULL) {
707 return result;
708 }
709
710 // If we reach this point, we're really out of memory. Try every trick
711 // we can to reclaim memory. Force collection of soft references. Force
712 // a complete compaction of the heap. Any additional methods for finding
713 // free memory should be here, especially if they are expensive. If this
714 // attempt fails, an OOM exception will be thrown.
715 {
716 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
717
718 do_collection(true, // full
719 true, // clear_all_soft_refs
720 size, // size
721 is_tlab, // is_tlab
722 GenCollectedHeap::OldGen); // max_generation
723 }
724
725 result = attempt_allocation(size, is_tlab, false /* first_only */);
726 if (result != NULL) {
727 assert(is_in_reserved(result), "result not in heap");
728 return result;
729 }
730
731 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
732 "Flag should have been handled and cleared prior to this point");
733
734 // What else? We might try synchronous finalization later. If the total
735 // space available is large enough for the allocation, then a more
736 // complete compaction phase than we've tried so far might be
737 // appropriate.
738 return NULL;
739 }
740
741 #ifdef ASSERT
742 class AssertNonScavengableClosure: public OopClosure {
743 public:
744 virtual void do_oop(oop* p) {
745 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
746 "Referent should not be scavengable."); }
747 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
748 };
749 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
750 #endif
751
752 void GenCollectedHeap::process_roots(ScanningOption so,
753 OopClosure* strong_roots,
754 CLDClosure* strong_cld_closure,
755 CLDClosure* weak_cld_closure,
756 CodeBlobToOopClosure* code_roots) {
757 // General roots.
758 assert(code_roots != NULL, "code root closure should always be set");
759
760 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
761
762 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
763 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
764
765 Threads::oops_do(strong_roots, roots_from_code_p);
766
767 OopStorageSet::strong_oops_do(strong_roots);
768
769 if (so & SO_ScavengeCodeCache) {
770 assert(code_roots != NULL, "must supply closure for code cache");
771
772 // We only visit parts of the CodeCache when scavenging.
773 ScavengableNMethods::nmethods_do(code_roots);
774 }
775 if (so & SO_AllCodeCache) {
776 assert(code_roots != NULL, "must supply closure for code cache");
777
778 // CMSCollector uses this to do intermediate-strength collections.
779 // We scan the entire code cache, since CodeCache::do_unloading is not called.
780 CodeCache::blobs_do(code_roots);
781 }
782 // Verify that the code cache contents are not subject to
783 // movement by a scavenging collection.
784 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
785 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
786 }
787
788 void GenCollectedHeap::full_process_roots(bool is_adjust_phase,
789 ScanningOption so,
790 bool only_strong_roots,
791 OopClosure* root_closure,
792 CLDClosure* cld_closure) {
793 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
794 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
795
796 process_roots(so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
797 }
798
799 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
800 WeakProcessor::oops_do(root_closure);
801 }
802
803 bool GenCollectedHeap::no_allocs_since_save_marks() {
804 return _young_gen->no_allocs_since_save_marks() &&
805 _old_gen->no_allocs_since_save_marks();
806 }
807
808 bool GenCollectedHeap::supports_inline_contig_alloc() const {
809 return _young_gen->supports_inline_contig_alloc();
810 }
811
812 HeapWord* volatile* GenCollectedHeap::top_addr() const {
813 return _young_gen->top_addr();
814 }
815
816 HeapWord** GenCollectedHeap::end_addr() const {
817 return _young_gen->end_addr();
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 MutexLocker ml(Heap_lock);
847 collect_locked(cause, max_generation);
848 }
849
850 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
851 // The caller has the Heap_lock
852 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
853 collect_locked(cause, OldGen);
854 }
855
856 // this is the private collection interface
857 // The Heap_lock is expected to be held on entry.
858
859 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
860 // Read the GC count while holding the Heap_lock
861 unsigned int gc_count_before = total_collections();
862 unsigned int full_gc_count_before = total_full_collections();
863
864 if (GCLocker::should_discard(cause, gc_count_before)) {
865 return;
866 }
867
868 {
869 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
870 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
871 cause, max_generation);
872 VMThread::execute(&op);
873 }
874 }
875
876 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
877 do_full_collection(clear_all_soft_refs, OldGen);
878 }
879
880 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
881 GenerationType last_generation) {
882 do_collection(true, // full
883 clear_all_soft_refs, // clear_all_soft_refs
884 0, // size
885 false, // is_tlab
886 last_generation); // last_generation
887 // Hack XXX FIX ME !!!
888 // A scavenge may not have been attempted, or may have
889 // been attempted and failed, because the old gen was too full
890 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
891 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
892 // This time allow the old gen to be collected as well
893 do_collection(true, // full
894 clear_all_soft_refs, // clear_all_soft_refs
895 0, // size
896 false, // is_tlab
897 OldGen); // last_generation
898 }
899 }
900
901 bool GenCollectedHeap::is_in_young(oop p) {
902 bool result = cast_from_oop<HeapWord*>(p) < _old_gen->reserved().start();
903 assert(result == _young_gen->is_in_reserved(p),
904 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
905 return result;
906 }
907
908 // Returns "TRUE" iff "p" points into the committed areas of the heap.
909 bool GenCollectedHeap::is_in(const void* p) const {
910 return _young_gen->is_in(p) || _old_gen->is_in(p);
911 }
912
913 #ifdef ASSERT
914 // Don't implement this by using is_in_young(). This method is used
915 // in some cases to check that is_in_young() is correct.
916 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
917 assert(is_in_reserved(p) || p == NULL,
918 "Does not work if address is non-null and outside of the heap");
919 return p < _young_gen->reserved().end() && p != NULL;
920 }
921 #endif
922
923 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
924 _young_gen->oop_iterate(cl);
925 _old_gen->oop_iterate(cl);
926 }
927
928 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
929 _young_gen->object_iterate(cl);
930 _old_gen->object_iterate(cl);
931 }
932
933 Space* GenCollectedHeap::space_containing(const void* addr) const {
934 Space* res = _young_gen->space_containing(addr);
935 if (res != NULL) {
936 return res;
937 }
938 res = _old_gen->space_containing(addr);
939 assert(res != NULL, "Could not find containing space");
940 return res;
941 }
942
943 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
944 assert(is_in_reserved(addr), "block_start of address outside of heap");
945 if (_young_gen->is_in_reserved(addr)) {
946 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
947 return _young_gen->block_start(addr);
948 }
949
950 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
951 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
952 return _old_gen->block_start(addr);
953 }
954
955 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
956 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
957 assert(block_start(addr) == addr, "addr must be a block start");
958 if (_young_gen->is_in_reserved(addr)) {
959 return _young_gen->block_is_obj(addr);
960 }
961
962 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
963 return _old_gen->block_is_obj(addr);
964 }
965
966 size_t GenCollectedHeap::tlab_capacity(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_capacity();
970 }
971
972 size_t GenCollectedHeap::tlab_used(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->tlab_used();
976 }
977
978 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
979 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
980 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
981 return _young_gen->unsafe_max_tlab_alloc();
982 }
983
984 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
985 size_t requested_size,
986 size_t* actual_size) {
987 bool gc_overhead_limit_was_exceeded;
988 HeapWord* result = mem_allocate_work(requested_size /* size */,
989 true /* is_tlab */,
990 &gc_overhead_limit_was_exceeded);
991 if (result != NULL) {
992 *actual_size = requested_size;
993 }
994
995 return result;
996 }
997
998 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
999 // from the list headed by "*prev_ptr".
1000 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1001 bool first = true;
1002 size_t min_size = 0; // "first" makes this conceptually infinite.
1003 ScratchBlock **smallest_ptr, *smallest;
1004 ScratchBlock *cur = *prev_ptr;
1005 while (cur) {
1006 assert(*prev_ptr == cur, "just checking");
1007 if (first || cur->num_words < min_size) {
1008 smallest_ptr = prev_ptr;
1009 smallest = cur;
1010 min_size = smallest->num_words;
1011 first = false;
1012 }
1013 prev_ptr = &cur->next;
1014 cur = cur->next;
1015 }
1016 smallest = *smallest_ptr;
1017 *smallest_ptr = smallest->next;
1018 return smallest;
1019 }
1020
1021 // Sort the scratch block list headed by res into decreasing size order,
1022 // and set "res" to the result.
1023 static void sort_scratch_list(ScratchBlock*& list) {
1024 ScratchBlock* sorted = NULL;
1025 ScratchBlock* unsorted = list;
1026 while (unsorted) {
1027 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1028 smallest->next = sorted;
1029 sorted = smallest;
1030 }
1031 list = sorted;
1032 }
1033
1034 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1035 size_t max_alloc_words) {
1036 ScratchBlock* res = NULL;
1037 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1038 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1039 sort_scratch_list(res);
1040 return res;
1041 }
1042
1043 void GenCollectedHeap::release_scratch() {
1044 _young_gen->reset_scratch();
1045 _old_gen->reset_scratch();
1046 }
1047
1048 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1049 void do_generation(Generation* gen) {
1050 gen->prepare_for_verify();
1051 }
1052 };
1053
1054 void GenCollectedHeap::prepare_for_verify() {
1055 ensure_parsability(false); // no need to retire TLABs
1056 GenPrepareForVerifyClosure blk;
1057 generation_iterate(&blk, false);
1058 }
1059
1060 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1061 bool old_to_young) {
1062 if (old_to_young) {
1063 cl->do_generation(_old_gen);
1064 cl->do_generation(_young_gen);
1065 } else {
1066 cl->do_generation(_young_gen);
1067 cl->do_generation(_old_gen);
1068 }
1069 }
1070
1071 bool GenCollectedHeap::is_maximal_no_gc() const {
1072 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1073 }
1074
1075 void GenCollectedHeap::save_marks() {
1076 _young_gen->save_marks();
1077 _old_gen->save_marks();
1078 }
1079
1080 GenCollectedHeap* GenCollectedHeap::heap() {
1081 // SerialHeap is the only subtype of GenCollectedHeap.
1082 return named_heap<GenCollectedHeap>(CollectedHeap::Serial);
1083 }
1084
1085 #if INCLUDE_SERIALGC
1086 void GenCollectedHeap::prepare_for_compaction() {
1087 // Start by compacting into same gen.
1088 CompactPoint cp(_old_gen);
1089 _old_gen->prepare_for_compaction(&cp);
1090 _young_gen->prepare_for_compaction(&cp);
1091 }
1092 #endif // INCLUDE_SERIALGC
1093
1094 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1095 log_debug(gc, verify)("%s", _old_gen->name());
1096 _old_gen->verify();
1097
1098 log_debug(gc, verify)("%s", _old_gen->name());
1099 _young_gen->verify();
1100
1101 log_debug(gc, verify)("RemSet");
1102 rem_set()->verify();
1103 }
1104
1105 void GenCollectedHeap::print_on(outputStream* st) const {
1106 if (_young_gen != NULL) {
1107 _young_gen->print_on(st);
1108 }
1109 if (_old_gen != NULL) {
1110 _old_gen->print_on(st);
1111 }
1112 MetaspaceUtils::print_on(st);
1113 }
1114
1115 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1116 }
1117
1118 bool GenCollectedHeap::print_location(outputStream* st, void* addr) const {
1119 return BlockLocationPrinter<GenCollectedHeap>::print_location(st, addr);
1120 }
1121
1122 void GenCollectedHeap::print_tracing_info() const {
1123 if (log_is_enabled(Debug, gc, heap, exit)) {
1124 LogStreamHandle(Debug, gc, heap, exit) lsh;
1125 _young_gen->print_summary_info_on(&lsh);
1126 _old_gen->print_summary_info_on(&lsh);
1127 }
1128 }
1129
1130 void GenCollectedHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
1131 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
1132
1133 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
1134 HEAP_CHANGE_FORMAT" "
1135 HEAP_CHANGE_FORMAT,
1136 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
1137 pre_gc_values.young_gen_used(),
1138 pre_gc_values.young_gen_capacity(),
1139 def_new_gen->used(),
1140 def_new_gen->capacity()),
1141 HEAP_CHANGE_FORMAT_ARGS("Eden",
1142 pre_gc_values.eden_used(),
1143 pre_gc_values.eden_capacity(),
1144 def_new_gen->eden()->used(),
1145 def_new_gen->eden()->capacity()),
1146 HEAP_CHANGE_FORMAT_ARGS("From",
1147 pre_gc_values.from_used(),
1148 pre_gc_values.from_capacity(),
1149 def_new_gen->from()->used(),
1150 def_new_gen->from()->capacity()));
1151 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
1152 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
1153 pre_gc_values.old_gen_used(),
1154 pre_gc_values.old_gen_capacity(),
1155 old_gen()->used(),
1156 old_gen()->capacity()));
1157 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1158 }
1159
1160 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1161 private:
1162 bool _full;
1163 public:
1164 void do_generation(Generation* gen) {
1165 gen->gc_prologue(_full);
1166 }
1167 GenGCPrologueClosure(bool full) : _full(full) {};
1168 };
1169
1170 void GenCollectedHeap::gc_prologue(bool full) {
1171 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1172
1173 // Fill TLAB's and such
1174 ensure_parsability(true); // retire TLABs
1175
1176 // Walk generations
1177 GenGCPrologueClosure blk(full);
1178 generation_iterate(&blk, false); // not old-to-young.
1179 };
1180
1181 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1182 private:
1183 bool _full;
1184 public:
1185 void do_generation(Generation* gen) {
1186 gen->gc_epilogue(_full);
1187 }
1188 GenGCEpilogueClosure(bool full) : _full(full) {};
1189 };
1190
1191 void GenCollectedHeap::gc_epilogue(bool full) {
1192 #if COMPILER2_OR_JVMCI
1193 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1194 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1195 guarantee(!CompilerConfig::is_c2_or_jvmci_compiler_enabled() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1196 #endif // COMPILER2_OR_JVMCI
1197
1198 resize_all_tlabs();
1199
1200 GenGCEpilogueClosure blk(full);
1201 generation_iterate(&blk, false); // not old-to-young.
1202
1203 MetaspaceCounters::update_performance_counters();
1204 };
1205
1206 #ifndef PRODUCT
1207 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1208 private:
1209 public:
1210 void do_generation(Generation* gen) {
1211 gen->record_spaces_top();
1212 }
1213 };
1214
1215 void GenCollectedHeap::record_gen_tops_before_GC() {
1216 if (ZapUnusedHeapArea) {
1217 GenGCSaveTopsBeforeGCClosure blk;
1218 generation_iterate(&blk, false); // not old-to-young.
1219 }
1220 }
1221 #endif // not PRODUCT
1222
1223 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1224 public:
1225 void do_generation(Generation* gen) {
1226 gen->ensure_parsability();
1227 }
1228 };
1229
1230 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1231 CollectedHeap::ensure_parsability(retire_tlabs);
1232 GenEnsureParsabilityClosure ep_cl;
1233 generation_iterate(&ep_cl, false);
1234 }
1235
1236 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1237 oop obj,
1238 size_t obj_size) {
1239 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1240 assert(obj_size == obj->size(), "bad obj_size passed in");
1241 HeapWord* result = NULL;
1242
1243 result = old_gen->expand_and_allocate(obj_size, false);
1244
1245 if (result != NULL) {
1246 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), result, obj_size);
1247 }
1248 return cast_to_oop(result);
1249 }