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.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 // Timer for individual generations. Last argument is false: no CR
318 // FIXME: We should try to start the timing earlier to cover more of the GC pause
319 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL);
320 TraceCollectorStats tcs(gen->counters());
321 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
322
323 size_t prev_used = gen->used();
324 gen->stat_record()->invocations++;
325 gen->stat_record()->accumulated_time.start();
326
327 // Must be done anew before each collection because
328 // a previous collection will do mangling and will
329 // change top of some spaces.
330 record_gen_tops_before_GC();
331
332 if (PrintGC && Verbose) {
333 // I didn't want to change the logging when removing the level concept,
334 // but I guess this logging could say young/old or something instead of 0/1.
335 uint level;
336 if (heap()->is_young_gen(gen)) {
337 level = 0;
338 } else {
339 level = 1;
340 }
341 gclog_or_tty->print("level=%u invoke=%d size=" SIZE_FORMAT,
342 level,
343 gen->stat_record()->invocations,
344 size * HeapWordSize);
345 }
346
347 if (run_verification && VerifyBeforeGC) {
348 HandleMark hm; // Discard invalid handles created during verification
349 Universe::verify(" VerifyBeforeGC:");
350 }
351 COMPILER2_PRESENT(DerivedPointerTable::clear());
352
353 if (restore_marks_for_biased_locking) {
354 // We perform this mark word preservation work lazily
355 // because it's only at this point that we know whether we
356 // absolutely have to do it; we want to avoid doing it for
357 // scavenge-only collections where it's unnecessary
358 BiasedLocking::preserve_marks();
359 }
360
361 // Do collection work
362 {
363 // Note on ref discovery: For what appear to be historical reasons,
364 // GCH enables and disabled (by enqueing) refs discovery.
365 // In the future this should be moved into the generation's
366 // collect method so that ref discovery and enqueueing concerns
367 // are local to a generation. The collect method could return
368 // an appropriate indication in the case that notification on
369 // the ref lock was needed. This will make the treatment of
370 // weak refs more uniform (and indeed remove such concerns
371 // from GCH). XXX
372
373 HandleMark hm; // Discard invalid handles created during gc
374 save_marks(); // save marks for all gens
375 // We want to discover references, but not process them yet.
376 // This mode is disabled in process_discovered_references if the
377 // generation does some collection work, or in
378 // enqueue_discovered_references if the generation returns
379 // without doing any work.
380 ReferenceProcessor* rp = gen->ref_processor();
381 // If the discovery of ("weak") refs in this generation is
382 // atomic wrt other collectors in this configuration, we
383 // are guaranteed to have empty discovered ref lists.
384 if (rp->discovery_is_atomic()) {
385 rp->enable_discovery();
386 rp->setup_policy(clear_soft_refs);
387 } else {
388 // collect() below will enable discovery as appropriate
389 }
390 gen->collect(full, clear_soft_refs, size, is_tlab);
391 if (!rp->enqueuing_is_done()) {
392 rp->enqueue_discovered_references();
393 } else {
394 rp->set_enqueuing_is_done(false);
395 }
396 rp->verify_no_references_recorded();
397 }
398
399 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
400
401 gen->stat_record()->accumulated_time.stop();
402
403 update_gc_stats(gen, full);
404
405 if (run_verification && VerifyAfterGC) {
406 HandleMark hm; // Discard invalid handles created during verification
407 Universe::verify(" VerifyAfterGC:");
408 }
409
410 if (PrintGCDetails) {
411 gclog_or_tty->print(":");
412 gen->print_heap_change(prev_used);
413 }
414 }
415
416 void GenCollectedHeap::do_collection(bool full,
417 bool clear_all_soft_refs,
418 size_t size,
419 bool is_tlab,
420 GenerationType max_generation) {
421 ResourceMark rm;
422 DEBUG_ONLY(Thread* my_thread = Thread::current();)
423
424 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
425 assert(my_thread->is_VM_thread() ||
426 my_thread->is_ConcurrentGC_thread(),
427 "incorrect thread type capability");
428 assert(Heap_lock->is_locked(),
429 "the requesting thread should have the Heap_lock");
430 guarantee(!is_gc_active(), "collection is not reentrant");
431
432 if (GC_locker::check_active_before_gc()) {
433 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
434 }
435
436 GCIdMarkAndRestore gc_id_mark;
437
438 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
439 collector_policy()->should_clear_all_soft_refs();
440
441 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
442
443 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
444
445 print_heap_before_gc();
446
447 {
448 FlagSetting fl(_is_gc_active, true);
449
450 bool complete = full && (max_generation == OldGen);
451 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
452 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
453 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL);
454
455 gc_prologue(complete);
456 increment_total_collections(complete);
457
458 size_t gch_prev_used = used();
459 bool run_verification = total_collections() >= VerifyGCStartAt;
460
461 bool prepared_for_verification = false;
462 bool collected_old = false;
463 bool old_collects_young = complete && !ScavengeBeforeFullGC;
464
465 if (!old_collects_young && _young_gen->should_collect(full, size, is_tlab)) {
466 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
467 prepare_for_verify();
468 prepared_for_verification = true;
469 }
470
471 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
472 collect_generation(_young_gen,
473 full,
474 size,
475 is_tlab,
476 run_verification && VerifyGCLevel <= 0,
477 do_clear_all_soft_refs,
478 false);
479
480 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
481 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
482 // Allocation request was met by young GC.
483 size = 0;
484 }
485 }
486
487 bool must_restore_marks_for_biased_locking = false;
488
489 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
490 GCIdMarkAndRestore gc_id_mark;
491 if (!complete) {
492 // The full_collections increment was missed above.
493 increment_total_full_collections();
494 }
495
496 pre_full_gc_dump(NULL); // do any pre full gc dumps
497
498 if (!prepared_for_verification && run_verification &&
499 VerifyGCLevel <= 1 && VerifyBeforeGC) {
500 prepare_for_verify();
501 }
502
503 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
504 collect_generation(_old_gen,
505 full,
506 size,
507 is_tlab,
508 run_verification && VerifyGCLevel <= 1,
509 do_clear_all_soft_refs,
510 true);
511
512 must_restore_marks_for_biased_locking = true;
513 collected_old = true;
514 }
515
516 // Update "complete" boolean wrt what actually transpired --
517 // for instance, a promotion failure could have led to
518 // a whole heap collection.
519 complete = complete || collected_old;
520
521 if (complete) { // We did a full collection
522 // FIXME: See comment at pre_full_gc_dump call
523 post_full_gc_dump(NULL); // do any post full gc dumps
524 }
525
526 if (PrintGCDetails) {
527 print_heap_change(gch_prev_used);
528
529 // Print metaspace info for full GC with PrintGCDetails flag.
530 if (complete) {
531 MetaspaceAux::print_metaspace_change(metadata_prev_used);
532 }
533 }
534
535 // Adjust generation sizes.
536 if (collected_old) {
537 _old_gen->compute_new_size();
538 }
539 _young_gen->compute_new_size();
540
541 if (complete) {
542 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
543 ClassLoaderDataGraph::purge();
544 MetaspaceAux::verify_metrics();
545 // Resize the metaspace capacity after full collections
546 MetaspaceGC::compute_new_size();
547 update_full_collections_completed();
548 }
549
550 // Track memory usage and detect low memory after GC finishes
551 MemoryService::track_memory_usage();
552
553 gc_epilogue(complete);
554
555 if (must_restore_marks_for_biased_locking) {
556 BiasedLocking::restore_marks();
557 }
558 }
559
560 print_heap_after_gc();
561
562 #ifdef TRACESPINNING
563 ParallelTaskTerminator::print_termination_counts();
564 #endif
565 }
566
567 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
568 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
569 }
570
571 #ifdef ASSERT
572 class AssertNonScavengableClosure: public OopClosure {
573 public:
574 virtual void do_oop(oop* p) {
575 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
576 "Referent should not be scavengable."); }
577 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
578 };
579 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
580 #endif
581
582 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
583 ScanningOption so,
584 OopClosure* strong_roots,
585 OopClosure* weak_roots,
586 CLDClosure* strong_cld_closure,
587 CLDClosure* weak_cld_closure,
588 CodeBlobClosure* code_roots) {
589 // General roots.
590 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
591 assert(code_roots != NULL, "code root closure should always be set");
592 // _n_termination for _process_strong_tasks should be set up stream
593 // in a method not running in a GC worker. Otherwise the GC worker
594 // could be trying to change the termination condition while the task
595 // is executing in another GC worker.
596
597 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
598 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
599 }
600
601 // Some CLDs contained in the thread frames should be considered strong.
602 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
603 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
604 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
605 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
606
607 bool is_par = scope->n_threads() > 1;
608 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
609
610 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
611 Universe::oops_do(strong_roots);
612 }
613 // Global (strong) JNI handles
614 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
615 JNIHandles::oops_do(strong_roots);
616 }
617
618 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
619 ObjectSynchronizer::oops_do(strong_roots);
620 }
621 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
622 FlatProfiler::oops_do(strong_roots);
623 }
624 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
625 Management::oops_do(strong_roots);
626 }
627 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
628 JvmtiExport::oops_do(strong_roots);
629 }
630
631 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
632 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
633 }
634
635 // All threads execute the following. A specific chunk of buckets
636 // from the StringTable are the individual tasks.
637 if (weak_roots != NULL) {
638 if (is_par) {
639 StringTable::possibly_parallel_oops_do(weak_roots);
640 } else {
641 StringTable::oops_do(weak_roots);
642 }
643 }
644
645 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
646 if (so & SO_ScavengeCodeCache) {
647 assert(code_roots != NULL, "must supply closure for code cache");
648
649 // We only visit parts of the CodeCache when scavenging.
650 CodeCache::scavenge_root_nmethods_do(code_roots);
651 }
652 if (so & SO_AllCodeCache) {
653 assert(code_roots != NULL, "must supply closure for code cache");
654
655 // CMSCollector uses this to do intermediate-strength collections.
656 // We scan the entire code cache, since CodeCache::do_unloading is not called.
657 CodeCache::blobs_do(code_roots);
658 }
659 // Verify that the code cache contents are not subject to
660 // movement by a scavenging collection.
661 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
662 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
663 }
664 }
665
666 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
667 GenerationType type,
668 bool young_gen_as_roots,
669 ScanningOption so,
670 bool only_strong_roots,
671 OopsInGenClosure* not_older_gens,
672 OopsInGenClosure* older_gens,
673 CLDClosure* cld_closure) {
674 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots;
675
676 bool is_moving_collection = false;
677 if (type == YoungGen || is_adjust_phase) {
678 // young collections are always moving
679 is_moving_collection = true;
680 }
681
682 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
683 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
684 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
685
686 process_roots(scope, so,
687 not_older_gens, weak_roots,
688 cld_closure, weak_cld_closure,
689 &mark_code_closure);
690
691 if (young_gen_as_roots) {
692 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
693 if (type == OldGen) {
694 not_older_gens->set_generation(_young_gen);
695 _young_gen->oop_iterate(not_older_gens);
696 }
697 not_older_gens->reset_generation();
698 }
699 }
700 // When collection is parallel, all threads get to cooperate to do
701 // old generation scanning.
702 if (type == YoungGen) {
703 older_gens->set_generation(_old_gen);
704 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
705 older_gens->reset_generation();
706 }
707
708 _process_strong_tasks->all_tasks_completed(scope->n_threads());
709 }
710
711
712 class AlwaysTrueClosure: public BoolObjectClosure {
713 public:
714 bool do_object_b(oop p) { return true; }
715 };
716 static AlwaysTrueClosure always_true;
717
718 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
719 JNIHandles::weak_oops_do(&always_true, root_closure);
720 _young_gen->ref_processor()->weak_oops_do(root_closure);
721 _old_gen->ref_processor()->weak_oops_do(root_closure);
722 }
723
724 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
725 void GenCollectedHeap:: \
726 oop_since_save_marks_iterate(GenerationType gen, \
727 OopClosureType* cur, \
728 OopClosureType* older) { \
729 if (gen == YoungGen) { \
730 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
731 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
732 } else { \
733 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
734 } \
735 }
736
737 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
738
739 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
740
741 bool GenCollectedHeap::no_allocs_since_save_marks() {
742 return _young_gen->no_allocs_since_save_marks() &&
743 _old_gen->no_allocs_since_save_marks();
744 }
745
746 bool GenCollectedHeap::supports_inline_contig_alloc() const {
747 return _young_gen->supports_inline_contig_alloc();
748 }
749
750 HeapWord** GenCollectedHeap::top_addr() const {
751 return _young_gen->top_addr();
752 }
753
754 HeapWord** GenCollectedHeap::end_addr() const {
755 return _young_gen->end_addr();
756 }
757
758 // public collection interfaces
759
760 void GenCollectedHeap::collect(GCCause::Cause cause) {
761 if (should_do_concurrent_full_gc(cause)) {
762 #if INCLUDE_ALL_GCS
763 // Mostly concurrent full collection.
764 collect_mostly_concurrent(cause);
765 #else // INCLUDE_ALL_GCS
766 ShouldNotReachHere();
767 #endif // INCLUDE_ALL_GCS
768 } else if (cause == GCCause::_wb_young_gc) {
769 // Young collection for the WhiteBox API.
770 collect(cause, YoungGen);
771 } else {
772 #ifdef ASSERT
773 if (cause == GCCause::_scavenge_alot) {
774 // Young collection only.
775 collect(cause, YoungGen);
776 } else {
777 // Stop-the-world full collection.
778 collect(cause, OldGen);
779 }
780 #else
781 // Stop-the-world full collection.
782 collect(cause, OldGen);
783 #endif
784 }
785 }
786
787 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
788 // The caller doesn't have the Heap_lock
789 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
790 MutexLocker ml(Heap_lock);
791 collect_locked(cause, max_generation);
792 }
793
794 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
795 // The caller has the Heap_lock
796 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
797 collect_locked(cause, OldGen);
798 }
799
800 // this is the private collection interface
801 // The Heap_lock is expected to be held on entry.
802
803 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
804 // Read the GC count while holding the Heap_lock
805 unsigned int gc_count_before = total_collections();
806 unsigned int full_gc_count_before = total_full_collections();
807 {
808 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
809 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
810 cause, max_generation);
811 VMThread::execute(&op);
812 }
813 }
814
815 #if INCLUDE_ALL_GCS
816 bool GenCollectedHeap::create_cms_collector() {
817
818 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
819 "Unexpected generation kinds");
820 // Skip two header words in the block content verification
821 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
822 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
823 CMSCollector* collector =
824 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen,
825 _rem_set,
826 _gen_policy->as_concurrent_mark_sweep_policy());
827
828 if (collector == NULL || !collector->completed_initialization()) {
829 if (collector) {
830 delete collector; // Be nice in embedded situation
831 }
832 vm_shutdown_during_initialization("Could not create CMS collector");
833 return false;
834 }
835 return true; // success
836 }
837
838 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
839 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
840
841 MutexLocker ml(Heap_lock);
842 // Read the GC counts while holding the Heap_lock
843 unsigned int full_gc_count_before = total_full_collections();
844 unsigned int gc_count_before = total_collections();
845 {
846 MutexUnlocker mu(Heap_lock);
847 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
848 VMThread::execute(&op);
849 }
850 }
851 #endif // INCLUDE_ALL_GCS
852
853 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
854 do_full_collection(clear_all_soft_refs, OldGen);
855 }
856
857 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
858 GenerationType last_generation) {
859 GenerationType local_last_generation;
860 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
861 gc_cause() == GCCause::_gc_locker) {
862 local_last_generation = YoungGen;
863 } else {
864 local_last_generation = last_generation;
865 }
866
867 do_collection(true, // full
868 clear_all_soft_refs, // clear_all_soft_refs
869 0, // size
870 false, // is_tlab
871 local_last_generation); // last_generation
872 // Hack XXX FIX ME !!!
873 // A scavenge may not have been attempted, or may have
874 // been attempted and failed, because the old gen was too full
875 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
876 incremental_collection_will_fail(false /* don't consult_young */)) {
877 if (PrintGCDetails) {
878 gclog_or_tty->print_cr("GC locker: Trying a full collection "
879 "because scavenge failed");
880 }
881 // This time allow the old gen to be collected as well
882 do_collection(true, // full
883 clear_all_soft_refs, // clear_all_soft_refs
884 0, // size
885 false, // is_tlab
886 OldGen); // last_generation
887 }
888 }
889
890 bool GenCollectedHeap::is_in_young(oop p) {
891 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
892 assert(result == _young_gen->is_in_reserved(p),
893 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
894 return result;
895 }
896
897 // Returns "TRUE" iff "p" points into the committed areas of the heap.
898 bool GenCollectedHeap::is_in(const void* p) const {
899 return _young_gen->is_in(p) || _old_gen->is_in(p);
900 }
901
902 #ifdef ASSERT
903 // Don't implement this by using is_in_young(). This method is used
904 // in some cases to check that is_in_young() is correct.
905 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
906 assert(is_in_reserved(p) || p == NULL,
907 "Does not work if address is non-null and outside of the heap");
908 return p < _young_gen->reserved().end() && p != NULL;
909 }
910 #endif
911
912 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
913 NoHeaderExtendedOopClosure no_header_cl(cl);
914 oop_iterate(&no_header_cl);
915 }
916
917 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
918 _young_gen->oop_iterate(cl);
919 _old_gen->oop_iterate(cl);
920 }
921
922 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
923 _young_gen->object_iterate(cl);
924 _old_gen->object_iterate(cl);
925 }
926
927 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
928 _young_gen->safe_object_iterate(cl);
929 _old_gen->safe_object_iterate(cl);
930 }
931
932 Space* GenCollectedHeap::space_containing(const void* addr) const {
933 Space* res = _young_gen->space_containing(addr);
934 if (res != NULL) {
935 return res;
936 }
937 res = _old_gen->space_containing(addr);
938 assert(res != NULL, "Could not find containing space");
939 return res;
940 }
941
942 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
943 assert(is_in_reserved(addr), "block_start of address outside of heap");
944 if (_young_gen->is_in_reserved(addr)) {
945 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
946 return _young_gen->block_start(addr);
947 }
948
949 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
950 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
951 return _old_gen->block_start(addr);
952 }
953
954 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
955 assert(is_in_reserved(addr), "block_size of address outside of heap");
956 if (_young_gen->is_in_reserved(addr)) {
957 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
958 return _young_gen->block_size(addr);
959 }
960
961 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
962 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
963 return _old_gen->block_size(addr);
964 }
965
966 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
967 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
968 assert(block_start(addr) == addr, "addr must be a block start");
969 if (_young_gen->is_in_reserved(addr)) {
970 return _young_gen->block_is_obj(addr);
971 }
972
973 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
974 return _old_gen->block_is_obj(addr);
975 }
976
977 bool GenCollectedHeap::supports_tlab_allocation() const {
978 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
979 return _young_gen->supports_tlab_allocation();
980 }
981
982 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
983 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
984 if (_young_gen->supports_tlab_allocation()) {
985 return _young_gen->tlab_capacity();
986 }
987 return 0;
988 }
989
990 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
991 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
992 if (_young_gen->supports_tlab_allocation()) {
993 return _young_gen->tlab_used();
994 }
995 return 0;
996 }
997
998 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
999 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1000 if (_young_gen->supports_tlab_allocation()) {
1001 return _young_gen->unsafe_max_tlab_alloc();
1002 }
1003 return 0;
1004 }
1005
1006 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1007 bool gc_overhead_limit_was_exceeded;
1008 return collector_policy()->mem_allocate_work(size /* size */,
1009 true /* is_tlab */,
1010 &gc_overhead_limit_was_exceeded);
1011 }
1012
1013 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1014 // from the list headed by "*prev_ptr".
1015 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1016 bool first = true;
1017 size_t min_size = 0; // "first" makes this conceptually infinite.
1018 ScratchBlock **smallest_ptr, *smallest;
1019 ScratchBlock *cur = *prev_ptr;
1020 while (cur) {
1021 assert(*prev_ptr == cur, "just checking");
1022 if (first || cur->num_words < min_size) {
1023 smallest_ptr = prev_ptr;
1024 smallest = cur;
1025 min_size = smallest->num_words;
1026 first = false;
1027 }
1028 prev_ptr = &cur->next;
1029 cur = cur->next;
1030 }
1031 smallest = *smallest_ptr;
1032 *smallest_ptr = smallest->next;
1033 return smallest;
1034 }
1035
1036 // Sort the scratch block list headed by res into decreasing size order,
1037 // and set "res" to the result.
1038 static void sort_scratch_list(ScratchBlock*& list) {
1039 ScratchBlock* sorted = NULL;
1040 ScratchBlock* unsorted = list;
1041 while (unsorted) {
1042 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1043 smallest->next = sorted;
1044 sorted = smallest;
1045 }
1046 list = sorted;
1047 }
1048
1049 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1050 size_t max_alloc_words) {
1051 ScratchBlock* res = NULL;
1052 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1053 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1054 sort_scratch_list(res);
1055 return res;
1056 }
1057
1058 void GenCollectedHeap::release_scratch() {
1059 _young_gen->reset_scratch();
1060 _old_gen->reset_scratch();
1061 }
1062
1063 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1064 void do_generation(Generation* gen) {
1065 gen->prepare_for_verify();
1066 }
1067 };
1068
1069 void GenCollectedHeap::prepare_for_verify() {
1070 ensure_parsability(false); // no need to retire TLABs
1071 GenPrepareForVerifyClosure blk;
1072 generation_iterate(&blk, false);
1073 }
1074
1075 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1076 bool old_to_young) {
1077 if (old_to_young) {
1078 cl->do_generation(_old_gen);
1079 cl->do_generation(_young_gen);
1080 } else {
1081 cl->do_generation(_young_gen);
1082 cl->do_generation(_old_gen);
1083 }
1084 }
1085
1086 bool GenCollectedHeap::is_maximal_no_gc() const {
1087 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1088 }
1089
1090 void GenCollectedHeap::save_marks() {
1091 _young_gen->save_marks();
1092 _old_gen->save_marks();
1093 }
1094
1095 GenCollectedHeap* GenCollectedHeap::heap() {
1096 CollectedHeap* heap = Universe::heap();
1097 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1098 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1099 return (GenCollectedHeap*)heap;
1100 }
1101
1102 void GenCollectedHeap::prepare_for_compaction() {
1103 // Start by compacting into same gen.
1104 CompactPoint cp(_old_gen);
1105 _old_gen->prepare_for_compaction(&cp);
1106 _young_gen->prepare_for_compaction(&cp);
1107 }
1108
1109 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1110 if (!silent) {
1111 gclog_or_tty->print("%s", _old_gen->name());
1112 gclog_or_tty->print(" ");
1113 }
1114 _old_gen->verify();
1115
1116 if (!silent) {
1117 gclog_or_tty->print("%s", _young_gen->name());
1118 gclog_or_tty->print(" ");
1119 }
1120 _young_gen->verify();
1121
1122 if (!silent) {
1123 gclog_or_tty->print("remset ");
1124 }
1125 rem_set()->verify();
1126 }
1127
1128 void GenCollectedHeap::print_on(outputStream* st) const {
1129 _young_gen->print_on(st);
1130 _old_gen->print_on(st);
1131 MetaspaceAux::print_on(st);
1132 }
1133
1134 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1135 if (workers() != NULL) {
1136 workers()->threads_do(tc);
1137 }
1138 #if INCLUDE_ALL_GCS
1139 if (UseConcMarkSweepGC) {
1140 ConcurrentMarkSweepThread::threads_do(tc);
1141 }
1142 #endif // INCLUDE_ALL_GCS
1143 }
1144
1145 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1146 #if INCLUDE_ALL_GCS
1147 if (UseConcMarkSweepGC) {
1148 workers()->print_worker_threads_on(st);
1149 ConcurrentMarkSweepThread::print_all_on(st);
1150 }
1151 #endif // INCLUDE_ALL_GCS
1152 }
1153
1154 void GenCollectedHeap::print_on_error(outputStream* st) const {
1155 this->CollectedHeap::print_on_error(st);
1156
1157 #if INCLUDE_ALL_GCS
1158 if (UseConcMarkSweepGC) {
1159 st->cr();
1160 CMSCollector::print_on_error(st);
1161 }
1162 #endif // INCLUDE_ALL_GCS
1163 }
1164
1165 void GenCollectedHeap::print_tracing_info() const {
1166 if (TraceYoungGenTime) {
1167 _young_gen->print_summary_info();
1168 }
1169 if (TraceOldGenTime) {
1170 _old_gen->print_summary_info();
1171 }
1172 }
1173
1174 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1175 if (PrintGCDetails && Verbose) {
1176 gclog_or_tty->print(" " SIZE_FORMAT
1177 "->" SIZE_FORMAT
1178 "(" SIZE_FORMAT ")",
1179 prev_used, used(), capacity());
1180 } else {
1181 gclog_or_tty->print(" " SIZE_FORMAT "K"
1182 "->" SIZE_FORMAT "K"
1183 "(" SIZE_FORMAT "K)",
1184 prev_used / K, used() / K, capacity() / K);
1185 }
1186 }
1187
1188 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1189 private:
1190 bool _full;
1191 public:
1192 void do_generation(Generation* gen) {
1193 gen->gc_prologue(_full);
1194 }
1195 GenGCPrologueClosure(bool full) : _full(full) {};
1196 };
1197
1198 void GenCollectedHeap::gc_prologue(bool full) {
1199 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1200
1201 always_do_update_barrier = false;
1202 // Fill TLAB's and such
1203 CollectedHeap::accumulate_statistics_all_tlabs();
1204 ensure_parsability(true); // retire TLABs
1205
1206 // Walk generations
1207 GenGCPrologueClosure blk(full);
1208 generation_iterate(&blk, false); // not old-to-young.
1209 };
1210
1211 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1212 private:
1213 bool _full;
1214 public:
1215 void do_generation(Generation* gen) {
1216 gen->gc_epilogue(_full);
1217 }
1218 GenGCEpilogueClosure(bool full) : _full(full) {};
1219 };
1220
1221 void GenCollectedHeap::gc_epilogue(bool full) {
1222 #if defined(COMPILER2) || INCLUDE_JVMCI
1223 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1224 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1225 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1226 #endif /* COMPILER2 || INCLUDE_JVMCI */
1227
1228 resize_all_tlabs();
1229
1230 GenGCEpilogueClosure blk(full);
1231 generation_iterate(&blk, false); // not old-to-young.
1232
1233 if (!CleanChunkPoolAsync) {
1234 Chunk::clean_chunk_pool();
1235 }
1236
1237 MetaspaceCounters::update_performance_counters();
1238 CompressedClassSpaceCounters::update_performance_counters();
1239
1240 always_do_update_barrier = UseConcMarkSweepGC;
1241 };
1242
1243 #ifndef PRODUCT
1244 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1245 private:
1246 public:
1247 void do_generation(Generation* gen) {
1248 gen->record_spaces_top();
1249 }
1250 };
1251
1252 void GenCollectedHeap::record_gen_tops_before_GC() {
1253 if (ZapUnusedHeapArea) {
1254 GenGCSaveTopsBeforeGCClosure blk;
1255 generation_iterate(&blk, false); // not old-to-young.
1256 }
1257 }
1258 #endif // not PRODUCT
1259
1260 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1261 public:
1262 void do_generation(Generation* gen) {
1263 gen->ensure_parsability();
1264 }
1265 };
1266
1267 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1268 CollectedHeap::ensure_parsability(retire_tlabs);
1269 GenEnsureParsabilityClosure ep_cl;
1270 generation_iterate(&ep_cl, false);
1271 }
1272
1273 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1274 oop obj,
1275 size_t obj_size) {
1276 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1277 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1278 HeapWord* result = NULL;
1279
1280 result = old_gen->expand_and_allocate(obj_size, false);
1281
1282 if (result != NULL) {
1283 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1284 }
1285 return oop(result);
1286 }
1287
1288 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1289 jlong _time; // in ms
1290 jlong _now; // in ms
1291
1292 public:
1293 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1294
1295 jlong time() { return _time; }
1296
1297 void do_generation(Generation* gen) {
1298 _time = MIN2(_time, gen->time_of_last_gc(_now));
1299 }
1300 };
1301
1302 jlong GenCollectedHeap::millis_since_last_gc() {
1303 // We need a monotonically non-decreasing time in ms but
1304 // os::javaTimeMillis() does not guarantee monotonicity.
1305 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1306 GenTimeOfLastGCClosure tolgc_cl(now);
1307 // iterate over generations getting the oldest
1308 // time that a generation was collected
1309 generation_iterate(&tolgc_cl, false);
1310
1311 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1312 // provided the underlying platform provides such a time source
1313 // (and it is bug free). So we still have to guard against getting
1314 // back a time later than 'now'.
1315 jlong retVal = now - tolgc_cl.time();
1316 if (retVal < 0) {
1317 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1318 return 0;
1319 }
1320 return retVal;
1321 }