1 /*
2 * Copyright (c) 2000, 2016, 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
171 os::trace_page_sizes("Heap",
172 collector_policy()->min_heap_byte_size(),
173 total_reserved,
174 alignment,
175 heap_rs->base(),
176 heap_rs->size());
177
178 return heap_rs->base();
179 }
180
181 void GenCollectedHeap::post_initialize() {
182 ref_processing_init();
183 assert((_young_gen->kind() == Generation::DefNew) ||
184 (_young_gen->kind() == Generation::ParNew),
185 "Wrong youngest generation type");
186 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
187
188 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
189 _old_gen->kind() == Generation::MarkSweepCompact,
190 "Wrong generation kind");
191
192 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
193 _old_gen->capacity(),
194 def_new_gen->from()->capacity());
195 _gen_policy->initialize_gc_policy_counters();
196 }
197
198 void GenCollectedHeap::ref_processing_init() {
199 _young_gen->ref_processor_init();
200 _old_gen->ref_processor_init();
201 }
202
203 size_t GenCollectedHeap::capacity() const {
204 return _young_gen->capacity() + _old_gen->capacity();
205 }
206
207 size_t GenCollectedHeap::used() const {
208 return _young_gen->used() + _old_gen->used();
209 }
210
211 void GenCollectedHeap::save_used_regions() {
212 _old_gen->save_used_region();
213 _young_gen->save_used_region();
214 }
215
216 size_t GenCollectedHeap::max_capacity() const {
217 return _young_gen->max_capacity() + _old_gen->max_capacity();
218 }
219
220 // Update the _full_collections_completed counter
221 // at the end of a stop-world full GC.
222 unsigned int GenCollectedHeap::update_full_collections_completed() {
223 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
224 assert(_full_collections_completed <= _total_full_collections,
225 "Can't complete more collections than were started");
226 _full_collections_completed = _total_full_collections;
227 ml.notify_all();
228 return _full_collections_completed;
229 }
230
231 // Update the _full_collections_completed counter, as appropriate,
232 // at the end of a concurrent GC cycle. Note the conditional update
233 // below to allow this method to be called by a concurrent collector
234 // without synchronizing in any manner with the VM thread (which
235 // may already have initiated a STW full collection "concurrently").
236 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
237 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
238 assert((_full_collections_completed <= _total_full_collections) &&
239 (count <= _total_full_collections),
240 "Can't complete more collections than were started");
241 if (count > _full_collections_completed) {
242 _full_collections_completed = count;
243 ml.notify_all();
244 }
245 return _full_collections_completed;
246 }
247
248
249 #ifndef PRODUCT
250 // Override of memory state checking method in CollectedHeap:
251 // Some collectors (CMS for example) can't have badHeapWordVal written
252 // in the first two words of an object. (For instance , in the case of
253 // CMS these words hold state used to synchronize between certain
254 // (concurrent) GC steps and direct allocating mutators.)
255 // The skip_header_HeapWords() method below, allows us to skip
256 // over the requisite number of HeapWord's. Note that (for
257 // generational collectors) this means that those many words are
258 // skipped in each object, irrespective of the generation in which
259 // that object lives. The resultant loss of precision seems to be
260 // harmless and the pain of avoiding that imprecision appears somewhat
261 // higher than we are prepared to pay for such rudimentary debugging
262 // support.
263 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
264 size_t size) {
265 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
266 // We are asked to check a size in HeapWords,
267 // but the memory is mangled in juint words.
268 juint* start = (juint*) (addr + skip_header_HeapWords());
269 juint* end = (juint*) (addr + size);
270 for (juint* slot = start; slot < end; slot += 1) {
271 assert(*slot == badHeapWordVal,
272 "Found non badHeapWordValue in pre-allocation check");
273 }
274 }
275 }
276 #endif
277
278 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
279 bool is_tlab,
280 bool first_only) {
281 HeapWord* res = NULL;
282
283 if (_young_gen->should_allocate(size, is_tlab)) {
284 res = _young_gen->allocate(size, is_tlab);
285 if (res != NULL || first_only) {
286 return res;
287 }
288 }
289
290 if (_old_gen->should_allocate(size, is_tlab)) {
291 res = _old_gen->allocate(size, is_tlab);
292 }
293
294 return res;
295 }
296
297 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
298 bool* gc_overhead_limit_was_exceeded) {
299 return gen_policy()->mem_allocate_work(size,
300 false /* is_tlab */,
301 gc_overhead_limit_was_exceeded);
302 }
303
304 bool GenCollectedHeap::must_clear_all_soft_refs() {
305 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
306 _gc_cause == GCCause::_wb_full_gc;
307 }
308
309 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
310 if (!UseConcMarkSweepGC) {
311 return false;
312 }
313
314 switch (cause) {
315 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
316 case GCCause::_java_lang_system_gc:
317 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
318 default: return false;
319 }
320 }
321
322 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
323 bool is_tlab, bool run_verification, bool clear_soft_refs,
324 bool restore_marks_for_biased_locking) {
325 FormatBuffer<> title("Collect gen: %s", gen->short_name());
326 GCTraceTime(Trace, gc, phases) t1(title);
327 TraceCollectorStats tcs(gen->counters());
328 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
329
330 gen->stat_record()->invocations++;
331 gen->stat_record()->accumulated_time.start();
332
333 // Must be done anew before each collection because
334 // a previous collection will do mangling and will
335 // change top of some spaces.
336 record_gen_tops_before_GC();
337
338 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
339
340 if (run_verification && VerifyBeforeGC) {
341 HandleMark hm; // Discard invalid handles created during verification
342 Universe::verify("Before GC");
343 }
344 COMPILER2_PRESENT(DerivedPointerTable::clear());
345
346 if (restore_marks_for_biased_locking) {
347 // We perform this mark word preservation work lazily
348 // because it's only at this point that we know whether we
349 // absolutely have to do it; we want to avoid doing it for
350 // scavenge-only collections where it's unnecessary
351 BiasedLocking::preserve_marks();
352 }
353
354 // Do collection work
355 {
356 // Note on ref discovery: For what appear to be historical reasons,
357 // GCH enables and disabled (by enqueing) refs discovery.
358 // In the future this should be moved into the generation's
359 // collect method so that ref discovery and enqueueing concerns
360 // are local to a generation. The collect method could return
361 // an appropriate indication in the case that notification on
362 // the ref lock was needed. This will make the treatment of
363 // weak refs more uniform (and indeed remove such concerns
364 // from GCH). XXX
365
366 HandleMark hm; // Discard invalid handles created during gc
367 save_marks(); // save marks for all gens
368 // We want to discover references, but not process them yet.
369 // This mode is disabled in process_discovered_references if the
370 // generation does some collection work, or in
371 // enqueue_discovered_references if the generation returns
372 // without doing any work.
373 ReferenceProcessor* rp = gen->ref_processor();
374 // If the discovery of ("weak") refs in this generation is
375 // atomic wrt other collectors in this configuration, we
376 // are guaranteed to have empty discovered ref lists.
377 if (rp->discovery_is_atomic()) {
378 rp->enable_discovery();
379 rp->setup_policy(clear_soft_refs);
380 } else {
381 // collect() below will enable discovery as appropriate
382 }
383 gen->collect(full, clear_soft_refs, size, is_tlab);
384 if (!rp->enqueuing_is_done()) {
385 rp->enqueue_discovered_references();
386 } else {
387 rp->set_enqueuing_is_done(false);
388 }
389 rp->verify_no_references_recorded();
390 }
391
392 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
393
394 gen->stat_record()->accumulated_time.stop();
395
396 update_gc_stats(gen, full);
397
398 if (run_verification && VerifyAfterGC) {
399 HandleMark hm; // Discard invalid handles created during verification
400 Universe::verify("After GC");
401 }
402 }
403
404 void GenCollectedHeap::do_collection(bool full,
405 bool clear_all_soft_refs,
406 size_t size,
407 bool is_tlab,
408 GenerationType max_generation) {
409 ResourceMark rm;
410 DEBUG_ONLY(Thread* my_thread = Thread::current();)
411
412 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
413 assert(my_thread->is_VM_thread() ||
414 my_thread->is_ConcurrentGC_thread(),
415 "incorrect thread type capability");
416 assert(Heap_lock->is_locked(),
417 "the requesting thread should have the Heap_lock");
418 guarantee(!is_gc_active(), "collection is not reentrant");
419
420 if (GCLocker::check_active_before_gc()) {
421 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
422 }
423
424 GCIdMarkAndRestore gc_id_mark;
425
426 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
427 collector_policy()->should_clear_all_soft_refs();
428
429 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
430
431 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
432
433 print_heap_before_gc();
434
435 {
436 FlagSetting fl(_is_gc_active, true);
437
438 bool complete = full && (max_generation == OldGen);
439 bool old_collects_young = complete && !ScavengeBeforeFullGC;
440 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
441
442 FormatBuffer<> gc_string("%s", "Pause ");
443 if (do_young_collection) {
444 gc_string.append("Young");
445 } else {
446 gc_string.append("Full");
447 }
448
449 GCTraceCPUTime tcpu;
450 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
451
452 gc_prologue(complete);
453 increment_total_collections(complete);
454
455 size_t young_prev_used = _young_gen->used();
456 size_t old_prev_used = _old_gen->used();
457
458 bool run_verification = total_collections() >= VerifyGCStartAt;
459
460 bool prepared_for_verification = false;
461 bool collected_old = false;
462
463 if (do_young_collection) {
464 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
465 prepare_for_verify();
466 prepared_for_verification = true;
467 }
468
469 collect_generation(_young_gen,
470 full,
471 size,
472 is_tlab,
473 run_verification && VerifyGCLevel <= 0,
474 do_clear_all_soft_refs,
475 false);
476
477 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
478 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
479 // Allocation request was met by young GC.
480 size = 0;
481 }
482 }
483
484 bool must_restore_marks_for_biased_locking = false;
485
486 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
487 if (!complete) {
488 // The full_collections increment was missed above.
489 increment_total_full_collections();
490 }
491
492 if (!prepared_for_verification && run_verification &&
493 VerifyGCLevel <= 1 && VerifyBeforeGC) {
494 prepare_for_verify();
495 }
496
497 if (do_young_collection) {
498 // We did a young GC. Need a new GC id for the old GC.
499 GCIdMarkAndRestore gc_id_mark;
500 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
501 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
502 } else {
503 // No young GC done. Use the same GC id as was set up earlier in this method.
504 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
505 }
506
507 must_restore_marks_for_biased_locking = true;
508 collected_old = true;
509 }
510
511 // Update "complete" boolean wrt what actually transpired --
512 // for instance, a promotion failure could have led to
513 // a whole heap collection.
514 complete = complete || collected_old;
515
516 print_heap_change(young_prev_used, old_prev_used);
517 MetaspaceAux::print_metaspace_change(metadata_prev_used);
518
519 // Adjust generation sizes.
520 if (collected_old) {
521 _old_gen->compute_new_size();
522 }
523 _young_gen->compute_new_size();
524
525 if (complete) {
526 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
527 ClassLoaderDataGraph::purge();
528 MetaspaceAux::verify_metrics();
529 // Resize the metaspace capacity after full collections
530 MetaspaceGC::compute_new_size();
531 update_full_collections_completed();
532 }
533
534 // Track memory usage and detect low memory after GC finishes
535 MemoryService::track_memory_usage();
536
537 gc_epilogue(complete);
538
539 if (must_restore_marks_for_biased_locking) {
540 BiasedLocking::restore_marks();
541 }
542 }
543
544 print_heap_after_gc();
545
546 #ifdef TRACESPINNING
547 ParallelTaskTerminator::print_termination_counts();
548 #endif
549 }
550
551 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
552 return gen_policy()->satisfy_failed_allocation(size, is_tlab);
553 }
554
555 #ifdef ASSERT
556 class AssertNonScavengableClosure: public OopClosure {
557 public:
558 virtual void do_oop(oop* p) {
559 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
560 "Referent should not be scavengable."); }
561 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
562 };
563 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
564 #endif
565
566 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
567 ScanningOption so,
568 OopClosure* strong_roots,
569 OopClosure* weak_roots,
570 CLDClosure* strong_cld_closure,
571 CLDClosure* weak_cld_closure,
572 CodeBlobToOopClosure* code_roots) {
573 // General roots.
574 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
575 assert(code_roots != NULL, "code root closure should always be set");
576 // _n_termination for _process_strong_tasks should be set up stream
577 // in a method not running in a GC worker. Otherwise the GC worker
578 // could be trying to change the termination condition while the task
579 // is executing in another GC worker.
580
581 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
582 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
583 }
584
585 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
586 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
587
588 bool is_par = scope->n_threads() > 1;
589 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
590
591 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
592 Universe::oops_do(strong_roots);
593 }
594 // Global (strong) JNI handles
595 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
596 JNIHandles::oops_do(strong_roots);
597 }
598
599 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
600 ObjectSynchronizer::oops_do(strong_roots);
601 }
602 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
603 FlatProfiler::oops_do(strong_roots);
604 }
605 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
606 Management::oops_do(strong_roots);
607 }
608 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
609 JvmtiExport::oops_do(strong_roots);
610 }
611
612 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
613 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
614 }
615
616 // All threads execute the following. A specific chunk of buckets
617 // from the StringTable are the individual tasks.
618 if (weak_roots != NULL) {
619 if (is_par) {
620 StringTable::possibly_parallel_oops_do(weak_roots);
621 } else {
622 StringTable::oops_do(weak_roots);
623 }
624 }
625
626 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
627 if (so & SO_ScavengeCodeCache) {
628 assert(code_roots != NULL, "must supply closure for code cache");
629
630 // We only visit parts of the CodeCache when scavenging.
631 CodeCache::scavenge_root_nmethods_do(code_roots);
632 }
633 if (so & SO_AllCodeCache) {
634 assert(code_roots != NULL, "must supply closure for code cache");
635
636 // CMSCollector uses this to do intermediate-strength collections.
637 // We scan the entire code cache, since CodeCache::do_unloading is not called.
638 CodeCache::blobs_do(code_roots);
639 }
640 // Verify that the code cache contents are not subject to
641 // movement by a scavenging collection.
642 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
643 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
644 }
645 }
646
647 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
648 OopsInGenClosure* root_closure,
649 OopsInGenClosure* old_gen_closure,
650 CLDClosure* cld_closure) {
651 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
652
653 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
654 cld_closure, cld_closure, &mark_code_closure);
655
656 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
657 root_closure->reset_generation();
658 }
659
660 // When collection is parallel, all threads get to cooperate to do
661 // old generation scanning.
662 old_gen_closure->set_generation(_old_gen);
663 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
664 old_gen_closure->reset_generation();
665
666 _process_strong_tasks->all_tasks_completed(scope->n_threads());
667 }
668
669 void GenCollectedHeap::conc_process_roots(StrongRootsScope* scope,
670 bool young_gen_as_roots,
671 ScanningOption so,
672 bool only_strong_roots,
673 OopsInGenClosure* root_closure,
674 CLDClosure* cld_closure) {
675 MarkingCodeBlobClosure mark_code_closure(root_closure, !CodeBlobToOopClosure::FixRelocations);
676 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
677 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
678
679 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
680
681 if (young_gen_as_roots &&
682 !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
683 root_closure->set_generation(_young_gen);
684 _young_gen->oop_iterate(root_closure);
685 root_closure->reset_generation();
686 }
687
688 _process_strong_tasks->all_tasks_completed(scope->n_threads());
689 }
690
691 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
692 bool only_strong_roots,
693 ScanningOption so,
694 bool is_adjust_phase,
695 OopsInGenClosure* root_closure,
696 CLDClosure* cld_closure) {
697 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
698 OopsInGenClosure* weak_roots = is_adjust_phase ? root_closure : NULL;
699 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
700
701 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
702
703 _process_strong_tasks->all_tasks_completed(scope->n_threads());
704 }
705
706 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
707 JNIHandles::weak_oops_do(root_closure);
708 _young_gen->ref_processor()->weak_oops_do(root_closure);
709 _old_gen->ref_processor()->weak_oops_do(root_closure);
710 }
711
712 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
713 void GenCollectedHeap:: \
714 oop_since_save_marks_iterate(GenerationType gen, \
715 OopClosureType* cur, \
716 OopClosureType* older) { \
717 if (gen == YoungGen) { \
718 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
719 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
720 } else { \
721 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
722 } \
723 }
724
725 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
726
727 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
728
729 bool GenCollectedHeap::no_allocs_since_save_marks() {
730 return _young_gen->no_allocs_since_save_marks() &&
731 _old_gen->no_allocs_since_save_marks();
732 }
733
734 bool GenCollectedHeap::supports_inline_contig_alloc() const {
735 return _young_gen->supports_inline_contig_alloc();
736 }
737
738 HeapWord** GenCollectedHeap::top_addr() const {
739 return _young_gen->top_addr();
740 }
741
742 HeapWord** GenCollectedHeap::end_addr() const {
743 return _young_gen->end_addr();
744 }
745
746 // public collection interfaces
747
748 void GenCollectedHeap::collect(GCCause::Cause cause) {
749 if (should_do_concurrent_full_gc(cause)) {
750 #if INCLUDE_ALL_GCS
751 // Mostly concurrent full collection.
752 collect_mostly_concurrent(cause);
753 #else // INCLUDE_ALL_GCS
754 ShouldNotReachHere();
755 #endif // INCLUDE_ALL_GCS
756 } else if (cause == GCCause::_wb_young_gc) {
757 // Young collection for the WhiteBox API.
758 collect(cause, YoungGen);
759 } else {
760 #ifdef ASSERT
761 if (cause == GCCause::_scavenge_alot) {
762 // Young collection only.
763 collect(cause, YoungGen);
764 } else {
765 // Stop-the-world full collection.
766 collect(cause, OldGen);
767 }
768 #else
769 // Stop-the-world full collection.
770 collect(cause, OldGen);
771 #endif
772 }
773 }
774
775 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
776 // The caller doesn't have the Heap_lock
777 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
778 MutexLocker ml(Heap_lock);
779 collect_locked(cause, max_generation);
780 }
781
782 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
783 // The caller has the Heap_lock
784 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
785 collect_locked(cause, OldGen);
786 }
787
788 // this is the private collection interface
789 // The Heap_lock is expected to be held on entry.
790
791 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
792 // Read the GC count while holding the Heap_lock
793 unsigned int gc_count_before = total_collections();
794 unsigned int full_gc_count_before = total_full_collections();
795 {
796 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
797 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
798 cause, max_generation);
799 VMThread::execute(&op);
800 }
801 }
802
803 #if INCLUDE_ALL_GCS
804 bool GenCollectedHeap::create_cms_collector() {
805
806 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
807 "Unexpected generation kinds");
808 // Skip two header words in the block content verification
809 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
810 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
811 CMSCollector* collector =
812 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen,
813 _rem_set,
814 _gen_policy->as_concurrent_mark_sweep_policy());
815
816 if (collector == NULL || !collector->completed_initialization()) {
817 if (collector) {
818 delete collector; // Be nice in embedded situation
819 }
820 vm_shutdown_during_initialization("Could not create CMS collector");
821 return false;
822 }
823 return true; // success
824 }
825
826 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
827 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
828
829 MutexLocker ml(Heap_lock);
830 // Read the GC counts while holding the Heap_lock
831 unsigned int full_gc_count_before = total_full_collections();
832 unsigned int gc_count_before = total_collections();
833 {
834 MutexUnlocker mu(Heap_lock);
835 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
836 VMThread::execute(&op);
837 }
838 }
839 #endif // INCLUDE_ALL_GCS
840
841 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
842 do_full_collection(clear_all_soft_refs, OldGen);
843 }
844
845 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
846 GenerationType last_generation) {
847 GenerationType local_last_generation;
848 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
849 gc_cause() == GCCause::_gc_locker) {
850 local_last_generation = YoungGen;
851 } else {
852 local_last_generation = last_generation;
853 }
854
855 do_collection(true, // full
856 clear_all_soft_refs, // clear_all_soft_refs
857 0, // size
858 false, // is_tlab
859 local_last_generation); // last_generation
860 // Hack XXX FIX ME !!!
861 // A scavenge may not have been attempted, or may have
862 // been attempted and failed, because the old gen was too full
863 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
864 incremental_collection_will_fail(false /* don't consult_young */)) {
865 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
866 // This time allow the old gen to be collected as well
867 do_collection(true, // full
868 clear_all_soft_refs, // clear_all_soft_refs
869 0, // size
870 false, // is_tlab
871 OldGen); // last_generation
872 }
873 }
874
875 bool GenCollectedHeap::is_in_young(oop p) {
876 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
877 assert(result == _young_gen->is_in_reserved(p),
878 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
879 return result;
880 }
881
882 // Returns "TRUE" iff "p" points into the committed areas of the heap.
883 bool GenCollectedHeap::is_in(const void* p) const {
884 return _young_gen->is_in(p) || _old_gen->is_in(p);
885 }
886
887 #ifdef ASSERT
888 // Don't implement this by using is_in_young(). This method is used
889 // in some cases to check that is_in_young() is correct.
890 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
891 assert(is_in_reserved(p) || p == NULL,
892 "Does not work if address is non-null and outside of the heap");
893 return p < _young_gen->reserved().end() && p != NULL;
894 }
895 #endif
896
897 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
898 NoHeaderExtendedOopClosure no_header_cl(cl);
899 oop_iterate(&no_header_cl);
900 }
901
902 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
903 _young_gen->oop_iterate(cl);
904 _old_gen->oop_iterate(cl);
905 }
906
907 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
908 _young_gen->object_iterate(cl);
909 _old_gen->object_iterate(cl);
910 }
911
912 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
913 _young_gen->safe_object_iterate(cl);
914 _old_gen->safe_object_iterate(cl);
915 }
916
917 Space* GenCollectedHeap::space_containing(const void* addr) const {
918 Space* res = _young_gen->space_containing(addr);
919 if (res != NULL) {
920 return res;
921 }
922 res = _old_gen->space_containing(addr);
923 assert(res != NULL, "Could not find containing space");
924 return res;
925 }
926
927 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
928 assert(is_in_reserved(addr), "block_start of address outside of heap");
929 if (_young_gen->is_in_reserved(addr)) {
930 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
931 return _young_gen->block_start(addr);
932 }
933
934 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
935 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
936 return _old_gen->block_start(addr);
937 }
938
939 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
940 assert(is_in_reserved(addr), "block_size of address outside of heap");
941 if (_young_gen->is_in_reserved(addr)) {
942 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
943 return _young_gen->block_size(addr);
944 }
945
946 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
947 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
948 return _old_gen->block_size(addr);
949 }
950
951 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
952 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
953 assert(block_start(addr) == addr, "addr must be a block start");
954 if (_young_gen->is_in_reserved(addr)) {
955 return _young_gen->block_is_obj(addr);
956 }
957
958 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
959 return _old_gen->block_is_obj(addr);
960 }
961
962 bool GenCollectedHeap::supports_tlab_allocation() const {
963 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
964 return _young_gen->supports_tlab_allocation();
965 }
966
967 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
968 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
969 if (_young_gen->supports_tlab_allocation()) {
970 return _young_gen->tlab_capacity();
971 }
972 return 0;
973 }
974
975 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
976 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
977 if (_young_gen->supports_tlab_allocation()) {
978 return _young_gen->tlab_used();
979 }
980 return 0;
981 }
982
983 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
984 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
985 if (_young_gen->supports_tlab_allocation()) {
986 return _young_gen->unsafe_max_tlab_alloc();
987 }
988 return 0;
989 }
990
991 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
992 bool gc_overhead_limit_was_exceeded;
993 return gen_policy()->mem_allocate_work(size /* size */,
994 true /* is_tlab */,
995 &gc_overhead_limit_was_exceeded);
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 CollectedHeap* heap = Universe::heap();
1082 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1083 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1084 return (GenCollectedHeap*)heap;
1085 }
1086
1087 void GenCollectedHeap::prepare_for_compaction() {
1088 // Start by compacting into same gen.
1089 CompactPoint cp(_old_gen);
1090 _old_gen->prepare_for_compaction(&cp);
1091 _young_gen->prepare_for_compaction(&cp);
1092 }
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 _young_gen->print_on(st);
1107 _old_gen->print_on(st);
1108 MetaspaceAux::print_on(st);
1109 }
1110
1111 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1112 if (workers() != NULL) {
1113 workers()->threads_do(tc);
1114 }
1115 #if INCLUDE_ALL_GCS
1116 if (UseConcMarkSweepGC) {
1117 ConcurrentMarkSweepThread::threads_do(tc);
1118 }
1119 #endif // INCLUDE_ALL_GCS
1120 }
1121
1122 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1123 #if INCLUDE_ALL_GCS
1124 if (UseConcMarkSweepGC) {
1125 workers()->print_worker_threads_on(st);
1126 ConcurrentMarkSweepThread::print_all_on(st);
1127 }
1128 #endif // INCLUDE_ALL_GCS
1129 }
1130
1131 void GenCollectedHeap::print_on_error(outputStream* st) const {
1132 this->CollectedHeap::print_on_error(st);
1133
1134 #if INCLUDE_ALL_GCS
1135 if (UseConcMarkSweepGC) {
1136 st->cr();
1137 CMSCollector::print_on_error(st);
1138 }
1139 #endif // INCLUDE_ALL_GCS
1140 }
1141
1142 void GenCollectedHeap::print_tracing_info() const {
1143 if (TraceYoungGenTime) {
1144 _young_gen->print_summary_info();
1145 }
1146 if (TraceOldGenTime) {
1147 _old_gen->print_summary_info();
1148 }
1149 }
1150
1151 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1152 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1153 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1154 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1155 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1156 }
1157
1158 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1159 private:
1160 bool _full;
1161 public:
1162 void do_generation(Generation* gen) {
1163 gen->gc_prologue(_full);
1164 }
1165 GenGCPrologueClosure(bool full) : _full(full) {};
1166 };
1167
1168 void GenCollectedHeap::gc_prologue(bool full) {
1169 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1170
1171 always_do_update_barrier = false;
1172 // Fill TLAB's and such
1173 CollectedHeap::accumulate_statistics_all_tlabs();
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 defined(COMPILER2) || INCLUDE_JVMCI
1193 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1194 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1195 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1196 #endif /* COMPILER2 || INCLUDE_JVMCI */
1197
1198 resize_all_tlabs();
1199
1200 GenGCEpilogueClosure blk(full);
1201 generation_iterate(&blk, false); // not old-to-young.
1202
1203 if (!CleanChunkPoolAsync) {
1204 Chunk::clean_chunk_pool();
1205 }
1206
1207 MetaspaceCounters::update_performance_counters();
1208 CompressedClassSpaceCounters::update_performance_counters();
1209
1210 always_do_update_barrier = UseConcMarkSweepGC;
1211 };
1212
1213 #ifndef PRODUCT
1214 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1215 private:
1216 public:
1217 void do_generation(Generation* gen) {
1218 gen->record_spaces_top();
1219 }
1220 };
1221
1222 void GenCollectedHeap::record_gen_tops_before_GC() {
1223 if (ZapUnusedHeapArea) {
1224 GenGCSaveTopsBeforeGCClosure blk;
1225 generation_iterate(&blk, false); // not old-to-young.
1226 }
1227 }
1228 #endif // not PRODUCT
1229
1230 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1231 public:
1232 void do_generation(Generation* gen) {
1233 gen->ensure_parsability();
1234 }
1235 };
1236
1237 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1238 CollectedHeap::ensure_parsability(retire_tlabs);
1239 GenEnsureParsabilityClosure ep_cl;
1240 generation_iterate(&ep_cl, false);
1241 }
1242
1243 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1244 oop obj,
1245 size_t obj_size) {
1246 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1247 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1248 HeapWord* result = NULL;
1249
1250 result = old_gen->expand_and_allocate(obj_size, false);
1251
1252 if (result != NULL) {
1253 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1254 }
1255 return oop(result);
1256 }
1257
1258 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1259 jlong _time; // in ms
1260 jlong _now; // in ms
1261
1262 public:
1263 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1264
1265 jlong time() { return _time; }
1266
1267 void do_generation(Generation* gen) {
1268 _time = MIN2(_time, gen->time_of_last_gc(_now));
1269 }
1270 };
1271
1272 jlong GenCollectedHeap::millis_since_last_gc() {
1273 // We need a monotonically non-decreasing time in ms but
1274 // os::javaTimeMillis() does not guarantee monotonicity.
1275 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1276 GenTimeOfLastGCClosure tolgc_cl(now);
1277 // iterate over generations getting the oldest
1278 // time that a generation was collected
1279 generation_iterate(&tolgc_cl, false);
1280
1281 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1282 // provided the underlying platform provides such a time source
1283 // (and it is bug free). So we still have to guard against getting
1284 // back a time later than 'now'.
1285 jlong retVal = now - tolgc_cl.time();
1286 if (retVal < 0) {
1287 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, retVal);)
1288 return 0;
1289 }
1290 return retVal;
1291 }
1292
1293 void GenCollectedHeap::stop() {
1294 #if INCLUDE_ALL_GCS
1295 if (UseConcMarkSweepGC) {
1296 ConcurrentMarkSweepThread::cmst()->stop();
1297 }
1298 #endif
1299 }