1 /*
2 * Copyright (c) 2000, 2015, 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/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/shared/collectedHeap.inline.hpp"
32 #include "gc/shared/collectorCounters.hpp"
33 #include "gc/shared/gcId.hpp"
34 #include "gc/shared/gcLocker.inline.hpp"
35 #include "gc/shared/gcTrace.hpp"
36 #include "gc/shared/gcTraceTime.inline.hpp"
37 #include "gc/shared/genCollectedHeap.hpp"
38 #include "gc/shared/genOopClosures.inline.hpp"
39 #include "gc/shared/generationSpec.hpp"
40 #include "gc/shared/space.hpp"
41 #include "gc/shared/strongRootsScope.hpp"
42 #include "gc/shared/vmGCOperations.hpp"
43 #include "gc/shared/workgroup.hpp"
44 #include "memory/filemap.hpp"
45 #include "memory/resourceArea.hpp"
46 #include "oops/oop.inline.hpp"
47 #include "runtime/biasedLocking.hpp"
48 #include "runtime/fprofiler.hpp"
49 #include "runtime/handles.hpp"
50 #include "runtime/handles.inline.hpp"
51 #include "runtime/java.hpp"
52 #include "runtime/vmThread.hpp"
53 #include "services/management.hpp"
54 #include "services/memoryService.hpp"
55 #include "utilities/macros.hpp"
56 #include "utilities/stack.inline.hpp"
57 #include "utilities/vmError.hpp"
58 #if INCLUDE_ALL_GCS
59 #include "gc/cms/concurrentMarkSweepThread.hpp"
60 #include "gc/cms/vmCMSOperations.hpp"
61 #endif // INCLUDE_ALL_GCS
62
63 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
64
65 // The set of potentially parallel tasks in root scanning.
66 enum GCH_strong_roots_tasks {
67 GCH_PS_Universe_oops_do,
68 GCH_PS_JNIHandles_oops_do,
69 GCH_PS_ObjectSynchronizer_oops_do,
70 GCH_PS_FlatProfiler_oops_do,
71 GCH_PS_Management_oops_do,
72 GCH_PS_SystemDictionary_oops_do,
73 GCH_PS_ClassLoaderDataGraph_oops_do,
74 GCH_PS_jvmti_oops_do,
75 GCH_PS_CodeCache_oops_do,
76 GCH_PS_younger_gens,
77 // Leave this one last.
78 GCH_PS_NumElements
79 };
80
81 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
82 CollectedHeap(),
83 _rem_set(NULL),
84 _gen_policy(policy),
85 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
86 _full_collections_completed(0)
87 {
88 assert(policy != NULL, "Sanity check");
89 if (UseConcMarkSweepGC) {
90 _workers = new WorkGang("GC Thread", ParallelGCThreads,
91 /* are_GC_task_threads */true,
92 /* are_ConcurrentGC_threads */false);
93 _workers->initialize_workers();
94 } else {
95 // Serial GC does not use workers.
96 _workers = NULL;
97 }
98 }
99
100 jint GenCollectedHeap::initialize() {
101 CollectedHeap::pre_initialize();
102
103 // While there are no constraints in the GC code that HeapWordSize
104 // be any particular value, there are multiple other areas in the
105 // system which believe this to be true (e.g. oop->object_size in some
106 // cases incorrectly returns the size in wordSize units rather than
107 // HeapWordSize).
108 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
109
110 // Allocate space for the heap.
111
112 char* heap_address;
113 ReservedSpace heap_rs;
114
115 size_t heap_alignment = collector_policy()->heap_alignment();
116
117 heap_address = allocate(heap_alignment, &heap_rs);
118
119 if (!heap_rs.is_reserved()) {
120 vm_shutdown_during_initialization(
121 "Could not reserve enough space for object heap");
122 return JNI_ENOMEM;
123 }
124
125 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
126
127 _rem_set = collector_policy()->create_rem_set(reserved_region());
128 set_barrier_set(rem_set()->bs());
129
130 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
131 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
132 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
133
134 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
135 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
136 clear_incremental_collection_failed();
137
138 #if INCLUDE_ALL_GCS
139 // If we are running CMS, create the collector responsible
140 // for collecting the CMS generations.
141 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
142 bool success = create_cms_collector();
143 if (!success) return JNI_ENOMEM;
144 }
145 #endif // INCLUDE_ALL_GCS
146
147 return JNI_OK;
148 }
149
150 char* GenCollectedHeap::allocate(size_t alignment,
151 ReservedSpace* heap_rs){
152 // Now figure out the total size.
153 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
154 assert(alignment % pageSize == 0, "Must be");
155
156 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
157 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
158
159 // Check for overflow.
160 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
161 if (total_reserved < young_spec->max_size()) {
162 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
163 "the maximum representable size");
164 }
165 assert(total_reserved % alignment == 0,
166 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
167 SIZE_FORMAT, total_reserved, alignment);
168
169 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
170 return heap_rs->base();
171 }
172
173 void GenCollectedHeap::post_initialize() {
174 CollectedHeap::post_initialize();
175 ref_processing_init();
176 assert((_young_gen->kind() == Generation::DefNew) ||
177 (_young_gen->kind() == Generation::ParNew),
178 "Wrong youngest generation type");
179 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
180
181 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
182 _old_gen->kind() == Generation::MarkSweepCompact,
183 "Wrong generation kind");
184
185 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
186 _old_gen->capacity(),
187 def_new_gen->from()->capacity());
188 _gen_policy->initialize_gc_policy_counters();
189 }
190
191 void GenCollectedHeap::ref_processing_init() {
192 _young_gen->ref_processor_init();
193 _old_gen->ref_processor_init();
194 }
195
196 size_t GenCollectedHeap::capacity() const {
197 return _young_gen->capacity() + _old_gen->capacity();
198 }
199
200 size_t GenCollectedHeap::used() const {
201 return _young_gen->used() + _old_gen->used();
202 }
203
204 void GenCollectedHeap::save_used_regions() {
205 _old_gen->save_used_region();
206 _young_gen->save_used_region();
207 }
208
209 size_t GenCollectedHeap::max_capacity() const {
210 return _young_gen->max_capacity() + _old_gen->max_capacity();
211 }
212
213 // Update the _full_collections_completed counter
214 // at the end of a stop-world full GC.
215 unsigned int GenCollectedHeap::update_full_collections_completed() {
216 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
217 assert(_full_collections_completed <= _total_full_collections,
218 "Can't complete more collections than were started");
219 _full_collections_completed = _total_full_collections;
220 ml.notify_all();
221 return _full_collections_completed;
222 }
223
224 // Update the _full_collections_completed counter, as appropriate,
225 // at the end of a concurrent GC cycle. Note the conditional update
226 // below to allow this method to be called by a concurrent collector
227 // without synchronizing in any manner with the VM thread (which
228 // may already have initiated a STW full collection "concurrently").
229 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
230 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
231 assert((_full_collections_completed <= _total_full_collections) &&
232 (count <= _total_full_collections),
233 "Can't complete more collections than were started");
234 if (count > _full_collections_completed) {
235 _full_collections_completed = count;
236 ml.notify_all();
237 }
238 return _full_collections_completed;
239 }
240
241
242 #ifndef PRODUCT
243 // Override of memory state checking method in CollectedHeap:
244 // Some collectors (CMS for example) can't have badHeapWordVal written
245 // in the first two words of an object. (For instance , in the case of
246 // CMS these words hold state used to synchronize between certain
247 // (concurrent) GC steps and direct allocating mutators.)
248 // The skip_header_HeapWords() method below, allows us to skip
249 // over the requisite number of HeapWord's. Note that (for
250 // generational collectors) this means that those many words are
251 // skipped in each object, irrespective of the generation in which
252 // that object lives. The resultant loss of precision seems to be
253 // harmless and the pain of avoiding that imprecision appears somewhat
254 // higher than we are prepared to pay for such rudimentary debugging
255 // support.
256 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
257 size_t size) {
258 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
259 // We are asked to check a size in HeapWords,
260 // but the memory is mangled in juint words.
261 juint* start = (juint*) (addr + skip_header_HeapWords());
262 juint* end = (juint*) (addr + size);
263 for (juint* slot = start; slot < end; slot += 1) {
264 assert(*slot == badHeapWordVal,
265 "Found non badHeapWordValue in pre-allocation check");
266 }
267 }
268 }
269 #endif
270
271 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
272 bool is_tlab,
273 bool first_only) {
274 HeapWord* res = NULL;
275
276 if (_young_gen->should_allocate(size, is_tlab)) {
277 res = _young_gen->allocate(size, is_tlab);
278 if (res != NULL || first_only) {
279 return res;
280 }
281 }
282
283 if (_old_gen->should_allocate(size, is_tlab)) {
284 res = _old_gen->allocate(size, is_tlab);
285 }
286
287 return res;
288 }
289
290 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
291 bool* gc_overhead_limit_was_exceeded) {
292 return collector_policy()->mem_allocate_work(size,
293 false /* is_tlab */,
294 gc_overhead_limit_was_exceeded);
295 }
296
297 bool GenCollectedHeap::must_clear_all_soft_refs() {
298 return _gc_cause == GCCause::_last_ditch_collection;
299 }
300
301 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
302 if (!UseConcMarkSweepGC) {
303 return false;
304 }
305
306 switch (cause) {
307 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
308 case GCCause::_java_lang_system_gc:
309 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
310 default: return false;
311 }
312 }
313
314 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
315 bool is_tlab, bool run_verification, bool clear_soft_refs,
316 bool restore_marks_for_biased_locking) {
317 FormatBuffer<> title("Collect gen: %s", gen->short_name());
318 GCTraceTime(Debug, gc) t1(title);
319 TraceCollectorStats tcs(gen->counters());
320 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
321
322 gen->stat_record()->invocations++;
323 gen->stat_record()->accumulated_time.start();
324
325 // Must be done anew before each collection because
326 // a previous collection will do mangling and will
327 // change top of some spaces.
328 record_gen_tops_before_GC();
329
330 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
331
332 if (run_verification && VerifyBeforeGC) {
333 HandleMark hm; // Discard invalid handles created during verification
334 Universe::verify("Before GC");
335 }
336 COMPILER2_PRESENT(DerivedPointerTable::clear());
337
338 if (restore_marks_for_biased_locking) {
339 // We perform this mark word preservation work lazily
340 // because it's only at this point that we know whether we
341 // absolutely have to do it; we want to avoid doing it for
342 // scavenge-only collections where it's unnecessary
343 BiasedLocking::preserve_marks();
344 }
345
346 // Do collection work
347 {
348 // Note on ref discovery: For what appear to be historical reasons,
349 // GCH enables and disabled (by enqueing) refs discovery.
350 // In the future this should be moved into the generation's
351 // collect method so that ref discovery and enqueueing concerns
352 // are local to a generation. The collect method could return
353 // an appropriate indication in the case that notification on
354 // the ref lock was needed. This will make the treatment of
355 // weak refs more uniform (and indeed remove such concerns
356 // from GCH). XXX
357
358 HandleMark hm; // Discard invalid handles created during gc
359 save_marks(); // save marks for all gens
360 // We want to discover references, but not process them yet.
361 // This mode is disabled in process_discovered_references if the
362 // generation does some collection work, or in
363 // enqueue_discovered_references if the generation returns
364 // without doing any work.
365 ReferenceProcessor* rp = gen->ref_processor();
366 // If the discovery of ("weak") refs in this generation is
367 // atomic wrt other collectors in this configuration, we
368 // are guaranteed to have empty discovered ref lists.
369 if (rp->discovery_is_atomic()) {
370 rp->enable_discovery();
371 rp->setup_policy(clear_soft_refs);
372 } else {
373 // collect() below will enable discovery as appropriate
374 }
375 gen->collect(full, clear_soft_refs, size, is_tlab);
376 if (!rp->enqueuing_is_done()) {
377 rp->enqueue_discovered_references();
378 } else {
379 rp->set_enqueuing_is_done(false);
380 }
381 rp->verify_no_references_recorded();
382 }
383
384 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
385
386 gen->stat_record()->accumulated_time.stop();
387
388 update_gc_stats(gen, full);
389
390 if (run_verification && VerifyAfterGC) {
391 HandleMark hm; // Discard invalid handles created during verification
392 Universe::verify("After GC");
393 }
394 }
395
396 void GenCollectedHeap::do_collection(bool full,
397 bool clear_all_soft_refs,
398 size_t size,
399 bool is_tlab,
400 GenerationType max_generation) {
401 ResourceMark rm;
402 DEBUG_ONLY(Thread* my_thread = Thread::current();)
403
404 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
405 assert(my_thread->is_VM_thread() ||
406 my_thread->is_ConcurrentGC_thread(),
407 "incorrect thread type capability");
408 assert(Heap_lock->is_locked(),
409 "the requesting thread should have the Heap_lock");
410 guarantee(!is_gc_active(), "collection is not reentrant");
411
412 if (GCLocker::check_active_before_gc()) {
413 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
414 }
415
416 GCIdMarkAndRestore gc_id_mark;
417
418 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
419 collector_policy()->should_clear_all_soft_refs();
420
421 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
422
423 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
424
425 print_heap_before_gc();
426
427 {
428 FlagSetting fl(_is_gc_active, true);
429
430 bool complete = full && (max_generation == OldGen);
431 bool old_collects_young = complete && !ScavengeBeforeFullGC;
432 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
433
434 FormatBuffer<> gc_string("%s", "Pause ");
435 if (do_young_collection) {
436 gc_string.append("Young");
437 } else {
438 gc_string.append("Full");
439 }
440
441 GCTraceCPUTime tcpu;
442 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
443
444 gc_prologue(complete);
445 increment_total_collections(complete);
446
447 size_t young_prev_used = _young_gen->used();
448 size_t old_prev_used = _old_gen->used();
449
450 bool run_verification = total_collections() >= VerifyGCStartAt;
451
452 bool prepared_for_verification = false;
453 bool collected_old = false;
454
455 if (do_young_collection) {
456 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
457 prepare_for_verify();
458 prepared_for_verification = true;
459 }
460
461 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
462 collect_generation(_young_gen,
463 full,
464 size,
465 is_tlab,
466 run_verification && VerifyGCLevel <= 0,
467 do_clear_all_soft_refs,
468 false);
469
470 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
471 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
472 // Allocation request was met by young GC.
473 size = 0;
474 }
475 }
476
477 bool must_restore_marks_for_biased_locking = false;
478
479 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
480 if (!complete) {
481 // The full_collections increment was missed above.
482 increment_total_full_collections();
483 }
484
485 pre_full_gc_dump(NULL); // do any pre full gc dumps
486
487 if (!prepared_for_verification && run_verification &&
488 VerifyGCLevel <= 1 && VerifyBeforeGC) {
489 prepare_for_verify();
490 }
491
492 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
493
494 if (do_young_collection) {
495 // We did a young GC. Need a new GC id for the old GC.
496 GCIdMarkAndRestore gc_id_mark;
497 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
498 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
499 } else {
500 // No young GC done. Use the same GC id as was set up earlier in this method.
501 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
502 }
503
504 must_restore_marks_for_biased_locking = true;
505 collected_old = true;
506 }
507
508 // Update "complete" boolean wrt what actually transpired --
509 // for instance, a promotion failure could have led to
510 // a whole heap collection.
511 complete = complete || collected_old;
512
513 if (complete) { // We did a full collection
514 // FIXME: See comment at pre_full_gc_dump call
515 post_full_gc_dump(NULL); // do any post full gc dumps
516 }
517
518 print_heap_change(young_prev_used, old_prev_used);
519 MetaspaceAux::print_metaspace_change(metadata_prev_used);
520
521 // Adjust generation sizes.
522 if (collected_old) {
523 _old_gen->compute_new_size();
524 }
525 _young_gen->compute_new_size();
526
527 if (complete) {
528 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
529 ClassLoaderDataGraph::purge();
530 MetaspaceAux::verify_metrics();
531 // Resize the metaspace capacity after full collections
532 MetaspaceGC::compute_new_size();
533 update_full_collections_completed();
534 }
535
536 // Track memory usage and detect low memory after GC finishes
537 MemoryService::track_memory_usage();
538
539 gc_epilogue(complete);
540
541 if (must_restore_marks_for_biased_locking) {
542 BiasedLocking::restore_marks();
543 }
544 }
545
546 print_heap_after_gc();
547
548 #ifdef TRACESPINNING
549 ParallelTaskTerminator::print_termination_counts();
550 #endif
551 }
552
553 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
554 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
555 }
556
557 #ifdef ASSERT
558 class AssertNonScavengableClosure: public OopClosure {
559 public:
560 virtual void do_oop(oop* p) {
561 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
562 "Referent should not be scavengable."); }
563 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
564 };
565 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
566 #endif
567
568 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
569 ScanningOption so,
570 OopClosure* strong_roots,
571 OopClosure* weak_roots,
572 CLDClosure* strong_cld_closure,
573 CLDClosure* weak_cld_closure,
574 CodeBlobClosure* code_roots) {
575 // General roots.
576 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
577 assert(code_roots != NULL, "code root closure should always be set");
578 // _n_termination for _process_strong_tasks should be set up stream
579 // in a method not running in a GC worker. Otherwise the GC worker
580 // could be trying to change the termination condition while the task
581 // is executing in another GC worker.
582
583 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
584 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
585 }
586
587 // Some CLDs contained in the thread frames should be considered strong.
588 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
589 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
590 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
591 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
592
593 bool is_par = scope->n_threads() > 1;
594 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
595
596 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
597 Universe::oops_do(strong_roots);
598 }
599 // Global (strong) JNI handles
600 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
601 JNIHandles::oops_do(strong_roots);
602 }
603
604 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
605 ObjectSynchronizer::oops_do(strong_roots);
606 }
607 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
608 FlatProfiler::oops_do(strong_roots);
609 }
610 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
611 Management::oops_do(strong_roots);
612 }
613 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
614 JvmtiExport::oops_do(strong_roots);
615 }
616
617 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
618 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
619 }
620
621 // All threads execute the following. A specific chunk of buckets
622 // from the StringTable are the individual tasks.
623 if (weak_roots != NULL) {
624 if (is_par) {
625 StringTable::possibly_parallel_oops_do(weak_roots);
626 } else {
627 StringTable::oops_do(weak_roots);
628 }
629 }
630
631 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
632 if (so & SO_ScavengeCodeCache) {
633 assert(code_roots != NULL, "must supply closure for code cache");
634
635 // We only visit parts of the CodeCache when scavenging.
636 CodeCache::scavenge_root_nmethods_do(code_roots);
637 }
638 if (so & SO_AllCodeCache) {
639 assert(code_roots != NULL, "must supply closure for code cache");
640
641 // CMSCollector uses this to do intermediate-strength collections.
642 // We scan the entire code cache, since CodeCache::do_unloading is not called.
643 CodeCache::blobs_do(code_roots);
644 }
645 // Verify that the code cache contents are not subject to
646 // movement by a scavenging collection.
647 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
648 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
649 }
650 }
651
652 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
653 GenerationType type,
654 bool young_gen_as_roots,
655 ScanningOption so,
656 bool only_strong_roots,
657 OopsInGenClosure* not_older_gens,
658 OopsInGenClosure* older_gens,
659 CLDClosure* cld_closure) {
660 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots;
661
662 bool is_moving_collection = false;
663 if (type == YoungGen || is_adjust_phase) {
664 // young collections are always moving
665 is_moving_collection = true;
666 }
667
668 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
669 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
670 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
671
672 process_roots(scope, so,
673 not_older_gens, weak_roots,
674 cld_closure, weak_cld_closure,
675 &mark_code_closure);
676
677 if (young_gen_as_roots) {
678 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
679 if (type == OldGen) {
680 not_older_gens->set_generation(_young_gen);
681 _young_gen->oop_iterate(not_older_gens);
682 }
683 not_older_gens->reset_generation();
684 }
685 }
686 // When collection is parallel, all threads get to cooperate to do
687 // old generation scanning.
688 if (type == YoungGen) {
689 older_gens->set_generation(_old_gen);
690 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
691 older_gens->reset_generation();
692 }
693
694 _process_strong_tasks->all_tasks_completed(scope->n_threads());
695 }
696
697
698 class AlwaysTrueClosure: public BoolObjectClosure {
699 public:
700 bool do_object_b(oop p) { return true; }
701 };
702 static AlwaysTrueClosure always_true;
703
704 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
705 JNIHandles::weak_oops_do(&always_true, root_closure);
706 _young_gen->ref_processor()->weak_oops_do(root_closure);
707 _old_gen->ref_processor()->weak_oops_do(root_closure);
708 }
709
710 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
711 void GenCollectedHeap:: \
712 oop_since_save_marks_iterate(GenerationType gen, \
713 OopClosureType* cur, \
714 OopClosureType* older) { \
715 if (gen == YoungGen) { \
716 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
717 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
718 } else { \
719 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
720 } \
721 }
722
723 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
724
725 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
726
727 bool GenCollectedHeap::no_allocs_since_save_marks() {
728 return _young_gen->no_allocs_since_save_marks() &&
729 _old_gen->no_allocs_since_save_marks();
730 }
731
732 bool GenCollectedHeap::supports_inline_contig_alloc() const {
733 return _young_gen->supports_inline_contig_alloc();
734 }
735
736 HeapWord** GenCollectedHeap::top_addr() const {
737 return _young_gen->top_addr();
738 }
739
740 HeapWord** GenCollectedHeap::end_addr() const {
741 return _young_gen->end_addr();
742 }
743
744 // public collection interfaces
745
746 void GenCollectedHeap::collect(GCCause::Cause cause) {
747 if (should_do_concurrent_full_gc(cause)) {
748 #if INCLUDE_ALL_GCS
749 // Mostly concurrent full collection.
750 collect_mostly_concurrent(cause);
751 #else // INCLUDE_ALL_GCS
752 ShouldNotReachHere();
753 #endif // INCLUDE_ALL_GCS
754 } else if (cause == GCCause::_wb_young_gc) {
755 // Young collection for the WhiteBox API.
756 collect(cause, YoungGen);
757 } else {
758 #ifdef ASSERT
759 if (cause == GCCause::_scavenge_alot) {
760 // Young collection only.
761 collect(cause, YoungGen);
762 } else {
763 // Stop-the-world full collection.
764 collect(cause, OldGen);
765 }
766 #else
767 // Stop-the-world full collection.
768 collect(cause, OldGen);
769 #endif
770 }
771 }
772
773 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
774 // The caller doesn't have the Heap_lock
775 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
776 MutexLocker ml(Heap_lock);
777 collect_locked(cause, max_generation);
778 }
779
780 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
781 // The caller has the Heap_lock
782 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
783 collect_locked(cause, OldGen);
784 }
785
786 // this is the private collection interface
787 // The Heap_lock is expected to be held on entry.
788
789 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
790 // Read the GC count while holding the Heap_lock
791 unsigned int gc_count_before = total_collections();
792 unsigned int full_gc_count_before = total_full_collections();
793 {
794 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
795 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
796 cause, max_generation);
797 VMThread::execute(&op);
798 }
799 }
800
801 #if INCLUDE_ALL_GCS
802 bool GenCollectedHeap::create_cms_collector() {
803
804 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
805 "Unexpected generation kinds");
806 // Skip two header words in the block content verification
807 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
808 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
809 CMSCollector* collector =
810 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen,
811 _rem_set,
812 _gen_policy->as_concurrent_mark_sweep_policy());
813
814 if (collector == NULL || !collector->completed_initialization()) {
815 if (collector) {
816 delete collector; // Be nice in embedded situation
817 }
818 vm_shutdown_during_initialization("Could not create CMS collector");
819 return false;
820 }
821 return true; // success
822 }
823
824 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
825 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
826
827 MutexLocker ml(Heap_lock);
828 // Read the GC counts while holding the Heap_lock
829 unsigned int full_gc_count_before = total_full_collections();
830 unsigned int gc_count_before = total_collections();
831 {
832 MutexUnlocker mu(Heap_lock);
833 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
834 VMThread::execute(&op);
835 }
836 }
837 #endif // INCLUDE_ALL_GCS
838
839 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
840 do_full_collection(clear_all_soft_refs, OldGen);
841 }
842
843 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
844 GenerationType last_generation) {
845 GenerationType local_last_generation;
846 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
847 gc_cause() == GCCause::_gc_locker) {
848 local_last_generation = YoungGen;
849 } else {
850 local_last_generation = last_generation;
851 }
852
853 do_collection(true, // full
854 clear_all_soft_refs, // clear_all_soft_refs
855 0, // size
856 false, // is_tlab
857 local_last_generation); // last_generation
858 // Hack XXX FIX ME !!!
859 // A scavenge may not have been attempted, or may have
860 // been attempted and failed, because the old gen was too full
861 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
862 incremental_collection_will_fail(false /* don't consult_young */)) {
863 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
864 // This time allow the old gen to be collected as well
865 do_collection(true, // full
866 clear_all_soft_refs, // clear_all_soft_refs
867 0, // size
868 false, // is_tlab
869 OldGen); // last_generation
870 }
871 }
872
873 bool GenCollectedHeap::is_in_young(oop p) {
874 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
875 assert(result == _young_gen->is_in_reserved(p),
876 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
877 return result;
878 }
879
880 // Returns "TRUE" iff "p" points into the committed areas of the heap.
881 bool GenCollectedHeap::is_in(const void* p) const {
882 return _young_gen->is_in(p) || _old_gen->is_in(p);
883 }
884
885 #ifdef ASSERT
886 // Don't implement this by using is_in_young(). This method is used
887 // in some cases to check that is_in_young() is correct.
888 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
889 assert(is_in_reserved(p) || p == NULL,
890 "Does not work if address is non-null and outside of the heap");
891 return p < _young_gen->reserved().end() && p != NULL;
892 }
893 #endif
894
895 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
896 NoHeaderExtendedOopClosure no_header_cl(cl);
897 oop_iterate(&no_header_cl);
898 }
899
900 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
901 _young_gen->oop_iterate(cl);
902 _old_gen->oop_iterate(cl);
903 }
904
905 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
906 _young_gen->object_iterate(cl);
907 _old_gen->object_iterate(cl);
908 }
909
910 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
911 _young_gen->safe_object_iterate(cl);
912 _old_gen->safe_object_iterate(cl);
913 }
914
915 Space* GenCollectedHeap::space_containing(const void* addr) const {
916 Space* res = _young_gen->space_containing(addr);
917 if (res != NULL) {
918 return res;
919 }
920 res = _old_gen->space_containing(addr);
921 assert(res != NULL, "Could not find containing space");
922 return res;
923 }
924
925 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
926 assert(is_in_reserved(addr), "block_start of address outside of heap");
927 if (_young_gen->is_in_reserved(addr)) {
928 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
929 return _young_gen->block_start(addr);
930 }
931
932 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
933 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
934 return _old_gen->block_start(addr);
935 }
936
937 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
938 assert(is_in_reserved(addr), "block_size of address outside of heap");
939 if (_young_gen->is_in_reserved(addr)) {
940 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
941 return _young_gen->block_size(addr);
942 }
943
944 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
945 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
946 return _old_gen->block_size(addr);
947 }
948
949 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
950 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
951 assert(block_start(addr) == addr, "addr must be a block start");
952 if (_young_gen->is_in_reserved(addr)) {
953 return _young_gen->block_is_obj(addr);
954 }
955
956 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
957 return _old_gen->block_is_obj(addr);
958 }
959
960 bool GenCollectedHeap::supports_tlab_allocation() const {
961 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
962 return _young_gen->supports_tlab_allocation();
963 }
964
965 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
966 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
967 if (_young_gen->supports_tlab_allocation()) {
968 return _young_gen->tlab_capacity();
969 }
970 return 0;
971 }
972
973 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
974 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
975 if (_young_gen->supports_tlab_allocation()) {
976 return _young_gen->tlab_used();
977 }
978 return 0;
979 }
980
981 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
982 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
983 if (_young_gen->supports_tlab_allocation()) {
984 return _young_gen->unsafe_max_tlab_alloc();
985 }
986 return 0;
987 }
988
989 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
990 bool gc_overhead_limit_was_exceeded;
991 return collector_policy()->mem_allocate_work(size /* size */,
992 true /* is_tlab */,
993 &gc_overhead_limit_was_exceeded);
994 }
995
996 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
997 // from the list headed by "*prev_ptr".
998 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
999 bool first = true;
1000 size_t min_size = 0; // "first" makes this conceptually infinite.
1001 ScratchBlock **smallest_ptr, *smallest;
1002 ScratchBlock *cur = *prev_ptr;
1003 while (cur) {
1004 assert(*prev_ptr == cur, "just checking");
1005 if (first || cur->num_words < min_size) {
1006 smallest_ptr = prev_ptr;
1007 smallest = cur;
1008 min_size = smallest->num_words;
1009 first = false;
1010 }
1011 prev_ptr = &cur->next;
1012 cur = cur->next;
1013 }
1014 smallest = *smallest_ptr;
1015 *smallest_ptr = smallest->next;
1016 return smallest;
1017 }
1018
1019 // Sort the scratch block list headed by res into decreasing size order,
1020 // and set "res" to the result.
1021 static void sort_scratch_list(ScratchBlock*& list) {
1022 ScratchBlock* sorted = NULL;
1023 ScratchBlock* unsorted = list;
1024 while (unsorted) {
1025 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1026 smallest->next = sorted;
1027 sorted = smallest;
1028 }
1029 list = sorted;
1030 }
1031
1032 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1033 size_t max_alloc_words) {
1034 ScratchBlock* res = NULL;
1035 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1036 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1037 sort_scratch_list(res);
1038 return res;
1039 }
1040
1041 void GenCollectedHeap::release_scratch() {
1042 _young_gen->reset_scratch();
1043 _old_gen->reset_scratch();
1044 }
1045
1046 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1047 void do_generation(Generation* gen) {
1048 gen->prepare_for_verify();
1049 }
1050 };
1051
1052 void GenCollectedHeap::prepare_for_verify() {
1053 ensure_parsability(false); // no need to retire TLABs
1054 GenPrepareForVerifyClosure blk;
1055 generation_iterate(&blk, false);
1056 }
1057
1058 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1059 bool old_to_young) {
1060 if (old_to_young) {
1061 cl->do_generation(_old_gen);
1062 cl->do_generation(_young_gen);
1063 } else {
1064 cl->do_generation(_young_gen);
1065 cl->do_generation(_old_gen);
1066 }
1067 }
1068
1069 bool GenCollectedHeap::is_maximal_no_gc() const {
1070 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1071 }
1072
1073 void GenCollectedHeap::save_marks() {
1074 _young_gen->save_marks();
1075 _old_gen->save_marks();
1076 }
1077
1078 GenCollectedHeap* GenCollectedHeap::heap() {
1079 CollectedHeap* heap = Universe::heap();
1080 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1081 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1082 return (GenCollectedHeap*)heap;
1083 }
1084
1085 void GenCollectedHeap::prepare_for_compaction() {
1086 // Start by compacting into same gen.
1087 CompactPoint cp(_old_gen);
1088 _old_gen->prepare_for_compaction(&cp);
1089 _young_gen->prepare_for_compaction(&cp);
1090 }
1091
1092 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1093 log_debug(gc, verify)("%s", _old_gen->name());
1094 _old_gen->verify();
1095
1096 log_debug(gc, verify)("%s", _old_gen->name());
1097 _young_gen->verify();
1098
1099 log_debug(gc, verify)("RemSet");
1100 rem_set()->verify();
1101 }
1102
1103 void GenCollectedHeap::print_on(outputStream* st) const {
1104 _young_gen->print_on(st);
1105 _old_gen->print_on(st);
1106 MetaspaceAux::print_on(st);
1107 }
1108
1109 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1110 if (workers() != NULL) {
1111 workers()->threads_do(tc);
1112 }
1113 #if INCLUDE_ALL_GCS
1114 if (UseConcMarkSweepGC) {
1115 ConcurrentMarkSweepThread::threads_do(tc);
1116 }
1117 #endif // INCLUDE_ALL_GCS
1118 }
1119
1120 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1121 #if INCLUDE_ALL_GCS
1122 if (UseConcMarkSweepGC) {
1123 workers()->print_worker_threads_on(st);
1124 ConcurrentMarkSweepThread::print_all_on(st);
1125 }
1126 #endif // INCLUDE_ALL_GCS
1127 }
1128
1129 void GenCollectedHeap::print_on_error(outputStream* st) const {
1130 this->CollectedHeap::print_on_error(st);
1131
1132 #if INCLUDE_ALL_GCS
1133 if (UseConcMarkSweepGC) {
1134 st->cr();
1135 CMSCollector::print_on_error(st);
1136 }
1137 #endif // INCLUDE_ALL_GCS
1138 }
1139
1140 void GenCollectedHeap::print_tracing_info() const {
1141 if (TraceYoungGenTime) {
1142 _young_gen->print_summary_info();
1143 }
1144 if (TraceOldGenTime) {
1145 _old_gen->print_summary_info();
1146 }
1147 }
1148
1149 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1150 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1151 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1152 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1153 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1154 }
1155
1156 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1157 private:
1158 bool _full;
1159 public:
1160 void do_generation(Generation* gen) {
1161 gen->gc_prologue(_full);
1162 }
1163 GenGCPrologueClosure(bool full) : _full(full) {};
1164 };
1165
1166 void GenCollectedHeap::gc_prologue(bool full) {
1167 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1168
1169 always_do_update_barrier = false;
1170 // Fill TLAB's and such
1171 CollectedHeap::accumulate_statistics_all_tlabs();
1172 ensure_parsability(true); // retire TLABs
1173
1174 // Walk generations
1175 GenGCPrologueClosure blk(full);
1176 generation_iterate(&blk, false); // not old-to-young.
1177 };
1178
1179 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1180 private:
1181 bool _full;
1182 public:
1183 void do_generation(Generation* gen) {
1184 gen->gc_epilogue(_full);
1185 }
1186 GenGCEpilogueClosure(bool full) : _full(full) {};
1187 };
1188
1189 void GenCollectedHeap::gc_epilogue(bool full) {
1190 #if defined(COMPILER2) || INCLUDE_JVMCI
1191 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1192 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1193 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1194 #endif /* COMPILER2 || INCLUDE_JVMCI */
1195
1196 resize_all_tlabs();
1197
1198 GenGCEpilogueClosure blk(full);
1199 generation_iterate(&blk, false); // not old-to-young.
1200
1201 if (!CleanChunkPoolAsync) {
1202 Chunk::clean_chunk_pool();
1203 }
1204
1205 MetaspaceCounters::update_performance_counters();
1206 CompressedClassSpaceCounters::update_performance_counters();
1207
1208 always_do_update_barrier = UseConcMarkSweepGC;
1209 };
1210
1211 #ifndef PRODUCT
1212 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1213 private:
1214 public:
1215 void do_generation(Generation* gen) {
1216 gen->record_spaces_top();
1217 }
1218 };
1219
1220 void GenCollectedHeap::record_gen_tops_before_GC() {
1221 if (ZapUnusedHeapArea) {
1222 GenGCSaveTopsBeforeGCClosure blk;
1223 generation_iterate(&blk, false); // not old-to-young.
1224 }
1225 }
1226 #endif // not PRODUCT
1227
1228 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1229 public:
1230 void do_generation(Generation* gen) {
1231 gen->ensure_parsability();
1232 }
1233 };
1234
1235 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1236 CollectedHeap::ensure_parsability(retire_tlabs);
1237 GenEnsureParsabilityClosure ep_cl;
1238 generation_iterate(&ep_cl, false);
1239 }
1240
1241 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1242 oop obj,
1243 size_t obj_size) {
1244 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1245 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1246 HeapWord* result = NULL;
1247
1248 result = old_gen->expand_and_allocate(obj_size, false);
1249
1250 if (result != NULL) {
1251 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1252 }
1253 return oop(result);
1254 }
1255
1256 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1257 jlong _time; // in ms
1258 jlong _now; // in ms
1259
1260 public:
1261 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1262
1263 jlong time() { return _time; }
1264
1265 void do_generation(Generation* gen) {
1266 _time = MIN2(_time, gen->time_of_last_gc(_now));
1267 }
1268 };
1269
1270 jlong GenCollectedHeap::millis_since_last_gc() {
1271 // We need a monotonically non-decreasing time in ms but
1272 // os::javaTimeMillis() does not guarantee monotonicity.
1273 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1274 GenTimeOfLastGCClosure tolgc_cl(now);
1275 // iterate over generations getting the oldest
1276 // time that a generation was collected
1277 generation_iterate(&tolgc_cl, false);
1278
1279 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1280 // provided the underlying platform provides such a time source
1281 // (and it is bug free). So we still have to guard against getting
1282 // back a time later than 'now'.
1283 jlong retVal = now - tolgc_cl.time();
1284 if (retVal < 0) {
1285 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1286 return 0;
1287 }
1288 return retVal;
1289 }
1290
1291 void GenCollectedHeap::stop() {
1292 #if INCLUDE_ALL_GCS
1293 if (UseConcMarkSweepGC) {
1294 ConcurrentMarkSweepThread::stop();
1295 }
1296 #endif
1297 }