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/workgroup.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/biasedLocking.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
125 _rem_set = create_rem_set(heap_rs.region());
126 _rem_set->initialize();
127 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
128 bs->initialize();
129 BarrierSet::set_barrier_set(bs);
130
131 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size());
132 _young_gen = _young_gen_spec->init(young_rs, rem_set());
133 ReservedSpace old_rs = heap_rs.last_part(_young_gen_spec->max_size());
134
135 old_rs = old_rs.first_part(_old_gen_spec->max_size());
136 _old_gen = _old_gen_spec->init(old_rs, rem_set());
137
138 GCInitLogger::print();
139
140 return JNI_OK;
141 }
142
143 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
144 return new CardTableRS(reserved_region);
145 }
146
147 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
148 size_t init_promo_size,
149 size_t init_survivor_size) {
150 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
151 _size_policy = new AdaptiveSizePolicy(init_eden_size,
152 init_promo_size,
153 init_survivor_size,
154 max_gc_pause_sec,
155 GCTimeRatio);
156 }
157
158 ReservedHeapSpace GenCollectedHeap::allocate(size_t alignment) {
159 // Now figure out the total size.
160 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
161 assert(alignment % pageSize == 0, "Must be");
162
163 // Check for overflow.
164 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
165 if (total_reserved < _young_gen_spec->max_size()) {
166 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
167 "the maximum representable size");
168 }
169 assert(total_reserved % alignment == 0,
170 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
171 SIZE_FORMAT, total_reserved, alignment);
172
173 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
174 size_t used_page_size = heap_rs.page_size();
175
176 os::trace_page_sizes("Heap",
177 MinHeapSize,
178 total_reserved,
179 used_page_size,
180 heap_rs.base(),
181 heap_rs.size());
182
183 return heap_rs;
184 }
185
186 class GenIsScavengable : public BoolObjectClosure {
187 public:
188 bool do_object_b(oop obj) {
189 return GenCollectedHeap::heap()->is_in_young(obj);
190 }
191 };
192
193 static GenIsScavengable _is_scavengable;
194
195 void GenCollectedHeap::post_initialize() {
196 CollectedHeap::post_initialize();
197 ref_processing_init();
198
199 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
200
201 initialize_size_policy(def_new_gen->eden()->capacity(),
202 _old_gen->capacity(),
203 def_new_gen->from()->capacity());
204
205 MarkSweep::initialize();
206
207 ScavengableNMethods::initialize(&_is_scavengable);
208 }
209
210 void GenCollectedHeap::ref_processing_init() {
211 _young_gen->ref_processor_init();
212 _old_gen->ref_processor_init();
213 }
214
215 PreGenGCValues GenCollectedHeap::get_pre_gc_values() const {
216 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
217
218 return PreGenGCValues(def_new_gen->used(),
219 def_new_gen->capacity(),
220 def_new_gen->eden()->used(),
221 def_new_gen->eden()->capacity(),
222 def_new_gen->from()->used(),
223 def_new_gen->from()->capacity(),
224 old_gen()->used(),
225 old_gen()->capacity());
226 }
227
228 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
229 return _young_gen_spec;
230 }
231
232 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
233 return _old_gen_spec;
234 }
235
236 size_t GenCollectedHeap::capacity() const {
237 return _young_gen->capacity() + _old_gen->capacity();
238 }
239
240 size_t GenCollectedHeap::used() const {
241 return _young_gen->used() + _old_gen->used();
242 }
243
244 void GenCollectedHeap::save_used_regions() {
245 _old_gen->save_used_region();
246 _young_gen->save_used_region();
247 }
248
249 size_t GenCollectedHeap::max_capacity() const {
250 return _young_gen->max_capacity() + _old_gen->max_capacity();
251 }
252
253 // Update the _full_collections_completed counter
254 // at the end of a stop-world full GC.
255 unsigned int GenCollectedHeap::update_full_collections_completed() {
256 assert(_full_collections_completed <= _total_full_collections,
257 "Can't complete more collections than were started");
258 _full_collections_completed = _total_full_collections;
259 return _full_collections_completed;
260 }
261
262 // Return true if any of the following is true:
263 // . the allocation won't fit into the current young gen heap
264 // . gc locker is occupied (jni critical section)
265 // . heap memory is tight -- the most recent previous collection
266 // was a full collection because a partial collection (would
267 // have) failed and is likely to fail again
268 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
269 size_t young_capacity = _young_gen->capacity_before_gc();
270 return (word_size > heap_word_size(young_capacity))
271 || GCLocker::is_active_and_needs_gc()
272 || incremental_collection_failed();
273 }
274
275 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
276 HeapWord* result = NULL;
277 if (_old_gen->should_allocate(size, is_tlab)) {
278 result = _old_gen->expand_and_allocate(size, is_tlab);
279 }
280 if (result == NULL) {
281 if (_young_gen->should_allocate(size, is_tlab)) {
282 result = _young_gen->expand_and_allocate(size, is_tlab);
283 }
284 }
285 assert(result == NULL || is_in_reserved(result), "result not in heap");
286 return result;
287 }
288
289 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
290 bool is_tlab,
291 bool* gc_overhead_limit_was_exceeded) {
292 // In general gc_overhead_limit_was_exceeded should be false so
293 // set it so here and reset it to true only if the gc time
294 // limit is being exceeded as checked below.
295 *gc_overhead_limit_was_exceeded = false;
296
297 HeapWord* result = NULL;
298
299 // Loop until the allocation is satisfied, or unsatisfied after GC.
300 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
301
302 // First allocation attempt is lock-free.
303 Generation *young = _young_gen;
304 assert(young->supports_inline_contig_alloc(),
305 "Otherwise, must do alloc within heap lock");
306 if (young->should_allocate(size, is_tlab)) {
307 result = young->par_allocate(size, is_tlab);
308 if (result != NULL) {
309 assert(is_in_reserved(result), "result not in heap");
310 return result;
311 }
312 }
313 uint gc_count_before; // Read inside the Heap_lock locked region.
314 {
315 MutexLocker ml(Heap_lock);
316 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
317 // Note that only large objects get a shot at being
318 // allocated in later generations.
319 bool first_only = !should_try_older_generation_allocation(size);
320
321 result = attempt_allocation(size, is_tlab, first_only);
322 if (result != NULL) {
323 assert(is_in_reserved(result), "result not in heap");
324 return result;
325 }
326
327 if (GCLocker::is_active_and_needs_gc()) {
328 if (is_tlab) {
329 return NULL; // Caller will retry allocating individual object.
330 }
331 if (!is_maximal_no_gc()) {
332 // Try and expand heap to satisfy request.
333 result = expand_heap_and_allocate(size, is_tlab);
334 // Result could be null if we are out of space.
335 if (result != NULL) {
336 return result;
337 }
338 }
339
340 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
341 return NULL; // We didn't get to do a GC and we didn't get any memory.
342 }
343
344 // If this thread is not in a jni critical section, we stall
345 // the requestor until the critical section has cleared and
346 // GC allowed. When the critical section clears, a GC is
347 // initiated by the last thread exiting the critical section; so
348 // we retry the allocation sequence from the beginning of the loop,
349 // rather than causing more, now probably unnecessary, GC attempts.
350 JavaThread* jthr = JavaThread::current();
351 if (!jthr->in_critical()) {
352 MutexUnlocker mul(Heap_lock);
353 // Wait for JNI critical section to be exited
354 GCLocker::stall_until_clear();
355 gclocker_stalled_count += 1;
356 continue;
357 } else {
358 if (CheckJNICalls) {
359 fatal("Possible deadlock due to allocating while"
360 " in jni critical section");
361 }
362 return NULL;
363 }
364 }
365
366 // Read the gc count while the heap lock is held.
367 gc_count_before = total_collections();
368 }
369
370 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
371 VMThread::execute(&op);
372 if (op.prologue_succeeded()) {
373 result = op.result();
374 if (op.gc_locked()) {
375 assert(result == NULL, "must be NULL if gc_locked() is true");
376 continue; // Retry and/or stall as necessary.
377 }
378
379 // Allocation has failed and a collection
380 // has been done. If the gc time limit was exceeded the
381 // this time, return NULL so that an out-of-memory
382 // will be thrown. Clear gc_overhead_limit_exceeded
383 // so that the overhead exceeded does not persist.
384
385 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
386 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
387
388 if (limit_exceeded && softrefs_clear) {
389 *gc_overhead_limit_was_exceeded = true;
390 size_policy()->set_gc_overhead_limit_exceeded(false);
391 if (op.result() != NULL) {
392 CollectedHeap::fill_with_object(op.result(), size);
393 }
394 return NULL;
395 }
396 assert(result == NULL || is_in_reserved(result),
397 "result not in heap");
398 return result;
399 }
400
401 // Give a warning if we seem to be looping forever.
402 if ((QueuedAllocationWarningCount > 0) &&
403 (try_count % QueuedAllocationWarningCount == 0)) {
404 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
405 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
406 }
407 }
408 }
409
410 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
411 bool is_tlab,
412 bool first_only) {
413 HeapWord* res = NULL;
414
415 if (_young_gen->should_allocate(size, is_tlab)) {
416 res = _young_gen->allocate(size, is_tlab);
417 if (res != NULL || first_only) {
418 return res;
419 }
420 }
421
422 if (_old_gen->should_allocate(size, is_tlab)) {
423 res = _old_gen->allocate(size, is_tlab);
424 }
425
426 return res;
427 }
428
429 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
430 bool* gc_overhead_limit_was_exceeded) {
431 return mem_allocate_work(size,
432 false /* is_tlab */,
433 gc_overhead_limit_was_exceeded);
434 }
435
436 bool GenCollectedHeap::must_clear_all_soft_refs() {
437 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
438 _gc_cause == GCCause::_wb_full_gc;
439 }
440
441 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
442 bool is_tlab, bool run_verification, bool clear_soft_refs,
443 bool restore_marks_for_biased_locking) {
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(), heap()->is_young_gen(gen) ? "end of minor GC" : "end of major GC");
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 if (restore_marks_for_biased_locking) {
465 // We perform this mark word preservation work lazily
466 // because it's only at this point that we know whether we
467 // absolutely have to do it; we want to avoid doing it for
468 // scavenge-only collections where it's unnecessary
469 BiasedLocking::preserve_marks();
470 }
471
472 // Do collection work
473 {
474 // Note on ref discovery: For what appear to be historical reasons,
475 // GCH enables and disabled (by enqueing) refs discovery.
476 // In the future this should be moved into the generation's
477 // collect method so that ref discovery and enqueueing concerns
478 // are local to a generation. The collect method could return
479 // an appropriate indication in the case that notification on
480 // the ref lock was needed. This will make the treatment of
481 // weak refs more uniform (and indeed remove such concerns
482 // from GCH). XXX
483
484 save_marks(); // save marks for all gens
485 // We want to discover references, but not process them yet.
486 // This mode is disabled in process_discovered_references if the
487 // generation does some collection work, or in
488 // enqueue_discovered_references if the generation returns
489 // without doing any work.
490 ReferenceProcessor* rp = gen->ref_processor();
491 // If the discovery of ("weak") refs in this generation is
492 // atomic wrt other collectors in this configuration, we
493 // are guaranteed to have empty discovered ref lists.
494 if (rp->discovery_is_atomic()) {
495 rp->enable_discovery();
496 rp->setup_policy(clear_soft_refs);
497 } else {
498 // collect() below will enable discovery as appropriate
499 }
500 gen->collect(full, clear_soft_refs, size, is_tlab);
501 if (!rp->enqueuing_is_done()) {
502 rp->disable_discovery();
503 } else {
504 rp->set_enqueuing_is_done(false);
505 }
506 rp->verify_no_references_recorded();
507 }
508
509 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
510
511 gen->stat_record()->accumulated_time.stop();
512
513 update_gc_stats(gen, full);
514
515 if (run_verification && VerifyAfterGC) {
516 Universe::verify("After GC");
517 }
518 }
519
520 void GenCollectedHeap::do_collection(bool full,
521 bool clear_all_soft_refs,
522 size_t size,
523 bool is_tlab,
524 GenerationType max_generation) {
525 ResourceMark rm;
526 DEBUG_ONLY(Thread* my_thread = Thread::current();)
527
528 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
529 assert(my_thread->is_VM_thread(), "only VM thread");
530 assert(Heap_lock->is_locked(),
531 "the requesting thread should have the Heap_lock");
532 guarantee(!is_gc_active(), "collection is not reentrant");
533
534 if (GCLocker::check_active_before_gc()) {
535 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
536 }
537
538 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
539 soft_ref_policy()->should_clear_all_soft_refs();
540
541 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
542
543 AutoModifyRestore<bool> temporarily(_is_gc_active, true);
544
545 bool complete = full && (max_generation == OldGen);
546 bool old_collects_young = complete && !ScavengeBeforeFullGC;
547 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
548
549 const PreGenGCValues pre_gc_values = get_pre_gc_values();
550
551 bool run_verification = total_collections() >= VerifyGCStartAt;
552 bool prepared_for_verification = false;
553 bool do_full_collection = false;
554
555 if (do_young_collection) {
556 GCIdMark gc_id_mark;
557 GCTraceCPUTime tcpu;
558 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
559
560 print_heap_before_gc();
561
562 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
563 prepare_for_verify();
564 prepared_for_verification = true;
565 }
566
567 gc_prologue(complete);
568 increment_total_collections(complete);
569
570 collect_generation(_young_gen,
571 full,
572 size,
573 is_tlab,
574 run_verification && VerifyGCLevel <= 0,
575 do_clear_all_soft_refs,
576 false);
577
578 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
579 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
580 // Allocation request was met by young GC.
581 size = 0;
582 }
583
584 // Ask if young collection is enough. If so, do the final steps for young collection,
585 // and fallthrough to the end.
586 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
587 if (!do_full_collection) {
588 // Adjust generation sizes.
589 _young_gen->compute_new_size();
590
591 print_heap_change(pre_gc_values);
592
593 // Track memory usage and detect low memory after GC finishes
594 MemoryService::track_memory_usage();
595
596 gc_epilogue(complete);
597 }
598
599 print_heap_after_gc();
600
601 } else {
602 // No young collection, ask if we need to perform Full collection.
603 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
604 }
605
606 if (do_full_collection) {
607 GCIdMark gc_id_mark;
608 GCTraceCPUTime tcpu;
609 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
610
611 print_heap_before_gc();
612
613 if (!prepared_for_verification && run_verification &&
614 VerifyGCLevel <= 1 && VerifyBeforeGC) {
615 prepare_for_verify();
616 }
617
618 if (!do_young_collection) {
619 gc_prologue(complete);
620 increment_total_collections(complete);
621 }
622
623 // Accounting quirk: total full collections would be incremented when "complete"
624 // is set, by calling increment_total_collections above. However, we also need to
625 // account Full collections that had "complete" unset.
626 if (!complete) {
627 increment_total_full_collections();
628 }
629
630 collect_generation(_old_gen,
631 full,
632 size,
633 is_tlab,
634 run_verification && VerifyGCLevel <= 1,
635 do_clear_all_soft_refs,
636 true);
637
638 // Adjust generation sizes.
639 _old_gen->compute_new_size();
640 _young_gen->compute_new_size();
641
642 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
643 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
644 DEBUG_ONLY(MetaspaceUtils::verify();)
645 // Resize the metaspace capacity after full collections
646 MetaspaceGC::compute_new_size();
647 update_full_collections_completed();
648
649 print_heap_change(pre_gc_values);
650
651 // Track memory usage and detect low memory after GC finishes
652 MemoryService::track_memory_usage();
653
654 // Need to tell the epilogue code we are done with Full GC, regardless what was
655 // the initial value for "complete" flag.
656 gc_epilogue(true);
657
658 BiasedLocking::restore_marks();
659
660 print_heap_after_gc();
661 }
662 }
663
664 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
665 GenCollectedHeap::GenerationType max_gen) const {
666 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
667 }
668
669 void GenCollectedHeap::register_nmethod(nmethod* nm) {
670 ScavengableNMethods::register_nmethod(nm);
671 }
672
673 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
674 ScavengableNMethods::unregister_nmethod(nm);
675 }
676
677 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
678 ScavengableNMethods::verify_nmethod(nm);
679 }
680
681 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
682 // Do nothing.
683 }
684
685 void GenCollectedHeap::prune_scavengable_nmethods() {
686 ScavengableNMethods::prune_nmethods();
687 }
688
689 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
690 GCCauseSetter x(this, GCCause::_allocation_failure);
691 HeapWord* result = NULL;
692
693 assert(size != 0, "Precondition violated");
694 if (GCLocker::is_active_and_needs_gc()) {
695 // GC locker is active; instead of a collection we will attempt
696 // to expand the heap, if there's room for expansion.
697 if (!is_maximal_no_gc()) {
698 result = expand_heap_and_allocate(size, is_tlab);
699 }
700 return result; // Could be null if we are out of space.
701 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
702 // Do an incremental collection.
703 do_collection(false, // full
704 false, // clear_all_soft_refs
705 size, // size
706 is_tlab, // is_tlab
707 GenCollectedHeap::OldGen); // max_generation
708 } else {
709 log_trace(gc)(" :: Trying full because partial may fail :: ");
710 // Try a full collection; see delta for bug id 6266275
711 // for the original code and why this has been simplified
712 // with from-space allocation criteria modified and
713 // such allocation moved out of the safepoint path.
714 do_collection(true, // full
715 false, // clear_all_soft_refs
716 size, // size
717 is_tlab, // is_tlab
718 GenCollectedHeap::OldGen); // max_generation
719 }
720
721 result = attempt_allocation(size, is_tlab, false /*first_only*/);
722
723 if (result != NULL) {
724 assert(is_in_reserved(result), "result not in heap");
725 return result;
726 }
727
728 // OK, collection failed, try expansion.
729 result = expand_heap_and_allocate(size, is_tlab);
730 if (result != NULL) {
731 return result;
732 }
733
734 // If we reach this point, we're really out of memory. Try every trick
735 // we can to reclaim memory. Force collection of soft references. Force
736 // a complete compaction of the heap. Any additional methods for finding
737 // free memory should be here, especially if they are expensive. If this
738 // attempt fails, an OOM exception will be thrown.
739 {
740 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
741
742 do_collection(true, // full
743 true, // clear_all_soft_refs
744 size, // size
745 is_tlab, // is_tlab
746 GenCollectedHeap::OldGen); // max_generation
747 }
748
749 result = attempt_allocation(size, is_tlab, false /* first_only */);
750 if (result != NULL) {
751 assert(is_in_reserved(result), "result not in heap");
752 return result;
753 }
754
755 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
756 "Flag should have been handled and cleared prior to this point");
757
758 // What else? We might try synchronous finalization later. If the total
759 // space available is large enough for the allocation, then a more
760 // complete compaction phase than we've tried so far might be
761 // appropriate.
762 return NULL;
763 }
764
765 #ifdef ASSERT
766 class AssertNonScavengableClosure: public OopClosure {
767 public:
768 virtual void do_oop(oop* p) {
769 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
770 "Referent should not be scavengable."); }
771 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
772 };
773 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
774 #endif
775
776 void GenCollectedHeap::process_roots(ScanningOption so,
777 OopClosure* strong_roots,
778 CLDClosure* strong_cld_closure,
779 CLDClosure* weak_cld_closure,
780 CodeBlobToOopClosure* code_roots) {
781 // General roots.
782 assert(code_roots != NULL, "code root closure should always be set");
783
784 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
785
786 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
787 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
788
789 Threads::oops_do(strong_roots, roots_from_code_p);
790
791 OopStorageSet::strong_oops_do(strong_roots);
792
793 if (so & SO_ScavengeCodeCache) {
794 assert(code_roots != NULL, "must supply closure for code cache");
795
796 // We only visit parts of the CodeCache when scavenging.
797 ScavengableNMethods::nmethods_do(code_roots);
798 }
799 if (so & SO_AllCodeCache) {
800 assert(code_roots != NULL, "must supply closure for code cache");
801
802 // CMSCollector uses this to do intermediate-strength collections.
803 // We scan the entire code cache, since CodeCache::do_unloading is not called.
804 CodeCache::blobs_do(code_roots);
805 }
806 // Verify that the code cache contents are not subject to
807 // movement by a scavenging collection.
808 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
809 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
810 }
811
812 void GenCollectedHeap::full_process_roots(bool is_adjust_phase,
813 ScanningOption so,
814 bool only_strong_roots,
815 OopClosure* root_closure,
816 CLDClosure* cld_closure) {
817 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
818 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
819
820 process_roots(so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
821 }
822
823 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
824 WeakProcessor::oops_do(root_closure);
825 _young_gen->ref_processor()->weak_oops_do(root_closure);
826 _old_gen->ref_processor()->weak_oops_do(root_closure);
827 }
828
829 bool GenCollectedHeap::no_allocs_since_save_marks() {
830 return _young_gen->no_allocs_since_save_marks() &&
831 _old_gen->no_allocs_since_save_marks();
832 }
833
834 bool GenCollectedHeap::supports_inline_contig_alloc() const {
835 return _young_gen->supports_inline_contig_alloc();
836 }
837
838 HeapWord* volatile* GenCollectedHeap::top_addr() const {
839 return _young_gen->top_addr();
840 }
841
842 HeapWord** GenCollectedHeap::end_addr() const {
843 return _young_gen->end_addr();
844 }
845
846 // public collection interfaces
847
848 void GenCollectedHeap::collect(GCCause::Cause cause) {
849 if ((cause == GCCause::_wb_young_gc) ||
850 (cause == GCCause::_gc_locker)) {
851 // Young collection for WhiteBox or GCLocker.
852 collect(cause, YoungGen);
853 } else {
854 #ifdef ASSERT
855 if (cause == GCCause::_scavenge_alot) {
856 // Young collection only.
857 collect(cause, YoungGen);
858 } else {
859 // Stop-the-world full collection.
860 collect(cause, OldGen);
861 }
862 #else
863 // Stop-the-world full collection.
864 collect(cause, OldGen);
865 #endif
866 }
867 }
868
869 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
870 // The caller doesn't have the Heap_lock
871 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
872 MutexLocker ml(Heap_lock);
873 collect_locked(cause, max_generation);
874 }
875
876 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
877 // The caller has the Heap_lock
878 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
879 collect_locked(cause, OldGen);
880 }
881
882 // this is the private collection interface
883 // The Heap_lock is expected to be held on entry.
884
885 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
886 // Read the GC count while holding the Heap_lock
887 unsigned int gc_count_before = total_collections();
888 unsigned int full_gc_count_before = total_full_collections();
889
890 if (GCLocker::should_discard(cause, gc_count_before)) {
891 return;
892 }
893
894 {
895 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
896 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
897 cause, max_generation);
898 VMThread::execute(&op);
899 }
900 }
901
902 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
903 do_full_collection(clear_all_soft_refs, OldGen);
904 }
905
906 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
907 GenerationType last_generation) {
908 do_collection(true, // full
909 clear_all_soft_refs, // clear_all_soft_refs
910 0, // size
911 false, // is_tlab
912 last_generation); // last_generation
913 // Hack XXX FIX ME !!!
914 // A scavenge may not have been attempted, or may have
915 // been attempted and failed, because the old gen was too full
916 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
917 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
918 // This time allow the old gen to be collected as well
919 do_collection(true, // full
920 clear_all_soft_refs, // clear_all_soft_refs
921 0, // size
922 false, // is_tlab
923 OldGen); // last_generation
924 }
925 }
926
927 bool GenCollectedHeap::is_in_young(oop p) {
928 bool result = cast_from_oop<HeapWord*>(p) < _old_gen->reserved().start();
929 assert(result == _young_gen->is_in_reserved(p),
930 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
931 return result;
932 }
933
934 // Returns "TRUE" iff "p" points into the committed areas of the heap.
935 bool GenCollectedHeap::is_in(const void* p) const {
936 return _young_gen->is_in(p) || _old_gen->is_in(p);
937 }
938
939 #ifdef ASSERT
940 // Don't implement this by using is_in_young(). This method is used
941 // in some cases to check that is_in_young() is correct.
942 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
943 assert(is_in_reserved(p) || p == NULL,
944 "Does not work if address is non-null and outside of the heap");
945 return p < _young_gen->reserved().end() && p != NULL;
946 }
947 #endif
948
949 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
950 _young_gen->oop_iterate(cl);
951 _old_gen->oop_iterate(cl);
952 }
953
954 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
955 _young_gen->object_iterate(cl);
956 _old_gen->object_iterate(cl);
957 }
958
959 Space* GenCollectedHeap::space_containing(const void* addr) const {
960 Space* res = _young_gen->space_containing(addr);
961 if (res != NULL) {
962 return res;
963 }
964 res = _old_gen->space_containing(addr);
965 assert(res != NULL, "Could not find containing space");
966 return res;
967 }
968
969 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
970 assert(is_in_reserved(addr), "block_start of address outside of heap");
971 if (_young_gen->is_in_reserved(addr)) {
972 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
973 return _young_gen->block_start(addr);
974 }
975
976 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
977 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
978 return _old_gen->block_start(addr);
979 }
980
981 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
982 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
983 assert(block_start(addr) == addr, "addr must be a block start");
984 if (_young_gen->is_in_reserved(addr)) {
985 return _young_gen->block_is_obj(addr);
986 }
987
988 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
989 return _old_gen->block_is_obj(addr);
990 }
991
992 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
993 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
994 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
995 return _young_gen->tlab_capacity();
996 }
997
998 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
999 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1000 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
1001 return _young_gen->tlab_used();
1002 }
1003
1004 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1005 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1006 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!");
1007 return _young_gen->unsafe_max_tlab_alloc();
1008 }
1009
1010 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1011 size_t requested_size,
1012 size_t* actual_size) {
1013 bool gc_overhead_limit_was_exceeded;
1014 HeapWord* result = mem_allocate_work(requested_size /* size */,
1015 true /* is_tlab */,
1016 &gc_overhead_limit_was_exceeded);
1017 if (result != NULL) {
1018 *actual_size = requested_size;
1019 }
1020
1021 return result;
1022 }
1023
1024 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1025 // from the list headed by "*prev_ptr".
1026 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1027 bool first = true;
1028 size_t min_size = 0; // "first" makes this conceptually infinite.
1029 ScratchBlock **smallest_ptr, *smallest;
1030 ScratchBlock *cur = *prev_ptr;
1031 while (cur) {
1032 assert(*prev_ptr == cur, "just checking");
1033 if (first || cur->num_words < min_size) {
1034 smallest_ptr = prev_ptr;
1035 smallest = cur;
1036 min_size = smallest->num_words;
1037 first = false;
1038 }
1039 prev_ptr = &cur->next;
1040 cur = cur->next;
1041 }
1042 smallest = *smallest_ptr;
1043 *smallest_ptr = smallest->next;
1044 return smallest;
1045 }
1046
1047 // Sort the scratch block list headed by res into decreasing size order,
1048 // and set "res" to the result.
1049 static void sort_scratch_list(ScratchBlock*& list) {
1050 ScratchBlock* sorted = NULL;
1051 ScratchBlock* unsorted = list;
1052 while (unsorted) {
1053 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1054 smallest->next = sorted;
1055 sorted = smallest;
1056 }
1057 list = sorted;
1058 }
1059
1060 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1061 size_t max_alloc_words) {
1062 ScratchBlock* res = NULL;
1063 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1064 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1065 sort_scratch_list(res);
1066 return res;
1067 }
1068
1069 void GenCollectedHeap::release_scratch() {
1070 _young_gen->reset_scratch();
1071 _old_gen->reset_scratch();
1072 }
1073
1074 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1075 void do_generation(Generation* gen) {
1076 gen->prepare_for_verify();
1077 }
1078 };
1079
1080 void GenCollectedHeap::prepare_for_verify() {
1081 ensure_parsability(false); // no need to retire TLABs
1082 GenPrepareForVerifyClosure blk;
1083 generation_iterate(&blk, false);
1084 }
1085
1086 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1087 bool old_to_young) {
1088 if (old_to_young) {
1089 cl->do_generation(_old_gen);
1090 cl->do_generation(_young_gen);
1091 } else {
1092 cl->do_generation(_young_gen);
1093 cl->do_generation(_old_gen);
1094 }
1095 }
1096
1097 bool GenCollectedHeap::is_maximal_no_gc() const {
1098 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1099 }
1100
1101 void GenCollectedHeap::save_marks() {
1102 _young_gen->save_marks();
1103 _old_gen->save_marks();
1104 }
1105
1106 GenCollectedHeap* GenCollectedHeap::heap() {
1107 // SerialHeap is the only subtype of GenCollectedHeap.
1108 return named_heap<GenCollectedHeap>(CollectedHeap::Serial);
1109 }
1110
1111 #if INCLUDE_SERIALGC
1112 void GenCollectedHeap::prepare_for_compaction() {
1113 // Start by compacting into same gen.
1114 CompactPoint cp(_old_gen);
1115 _old_gen->prepare_for_compaction(&cp);
1116 _young_gen->prepare_for_compaction(&cp);
1117 }
1118 #endif // INCLUDE_SERIALGC
1119
1120 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1121 log_debug(gc, verify)("%s", _old_gen->name());
1122 _old_gen->verify();
1123
1124 log_debug(gc, verify)("%s", _old_gen->name());
1125 _young_gen->verify();
1126
1127 log_debug(gc, verify)("RemSet");
1128 rem_set()->verify();
1129 }
1130
1131 void GenCollectedHeap::print_on(outputStream* st) const {
1132 if (_young_gen != NULL) {
1133 _young_gen->print_on(st);
1134 }
1135 if (_old_gen != NULL) {
1136 _old_gen->print_on(st);
1137 }
1138 MetaspaceUtils::print_on(st);
1139 }
1140
1141 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1142 }
1143
1144 bool GenCollectedHeap::print_location(outputStream* st, void* addr) const {
1145 return BlockLocationPrinter<GenCollectedHeap>::print_location(st, addr);
1146 }
1147
1148 void GenCollectedHeap::print_tracing_info() const {
1149 if (log_is_enabled(Debug, gc, heap, exit)) {
1150 LogStreamHandle(Debug, gc, heap, exit) lsh;
1151 _young_gen->print_summary_info_on(&lsh);
1152 _old_gen->print_summary_info_on(&lsh);
1153 }
1154 }
1155
1156 void GenCollectedHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
1157 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
1158
1159 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
1160 HEAP_CHANGE_FORMAT" "
1161 HEAP_CHANGE_FORMAT,
1162 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
1163 pre_gc_values.young_gen_used(),
1164 pre_gc_values.young_gen_capacity(),
1165 def_new_gen->used(),
1166 def_new_gen->capacity()),
1167 HEAP_CHANGE_FORMAT_ARGS("Eden",
1168 pre_gc_values.eden_used(),
1169 pre_gc_values.eden_capacity(),
1170 def_new_gen->eden()->used(),
1171 def_new_gen->eden()->capacity()),
1172 HEAP_CHANGE_FORMAT_ARGS("From",
1173 pre_gc_values.from_used(),
1174 pre_gc_values.from_capacity(),
1175 def_new_gen->from()->used(),
1176 def_new_gen->from()->capacity()));
1177 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
1178 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
1179 pre_gc_values.old_gen_used(),
1180 pre_gc_values.old_gen_capacity(),
1181 old_gen()->used(),
1182 old_gen()->capacity()));
1183 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1184 }
1185
1186 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1187 private:
1188 bool _full;
1189 public:
1190 void do_generation(Generation* gen) {
1191 gen->gc_prologue(_full);
1192 }
1193 GenGCPrologueClosure(bool full) : _full(full) {};
1194 };
1195
1196 void GenCollectedHeap::gc_prologue(bool full) {
1197 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1198
1199 // Fill TLAB's and such
1200 ensure_parsability(true); // retire TLABs
1201
1202 // Walk generations
1203 GenGCPrologueClosure blk(full);
1204 generation_iterate(&blk, false); // not old-to-young.
1205 };
1206
1207 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1208 private:
1209 bool _full;
1210 public:
1211 void do_generation(Generation* gen) {
1212 gen->gc_epilogue(_full);
1213 }
1214 GenGCEpilogueClosure(bool full) : _full(full) {};
1215 };
1216
1217 void GenCollectedHeap::gc_epilogue(bool full) {
1218 #if COMPILER2_OR_JVMCI
1219 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1220 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1221 guarantee(!CompilerConfig::is_c2_or_jvmci_compiler_enabled() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1222 #endif // COMPILER2_OR_JVMCI
1223
1224 resize_all_tlabs();
1225
1226 GenGCEpilogueClosure blk(full);
1227 generation_iterate(&blk, false); // not old-to-young.
1228
1229 MetaspaceCounters::update_performance_counters();
1230 };
1231
1232 #ifndef PRODUCT
1233 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1234 private:
1235 public:
1236 void do_generation(Generation* gen) {
1237 gen->record_spaces_top();
1238 }
1239 };
1240
1241 void GenCollectedHeap::record_gen_tops_before_GC() {
1242 if (ZapUnusedHeapArea) {
1243 GenGCSaveTopsBeforeGCClosure blk;
1244 generation_iterate(&blk, false); // not old-to-young.
1245 }
1246 }
1247 #endif // not PRODUCT
1248
1249 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1250 public:
1251 void do_generation(Generation* gen) {
1252 gen->ensure_parsability();
1253 }
1254 };
1255
1256 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1257 CollectedHeap::ensure_parsability(retire_tlabs);
1258 GenEnsureParsabilityClosure ep_cl;
1259 generation_iterate(&ep_cl, false);
1260 }
1261
1262 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1263 oop obj,
1264 size_t obj_size) {
1265 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1266 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1267 HeapWord* result = NULL;
1268
1269 result = old_gen->expand_and_allocate(obj_size, false);
1270
1271 if (result != NULL) {
1272 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), result, obj_size);
1273 }
1274 return cast_to_oop(result);
1275 }