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/gcLocker.inline.hpp"
34 #include "gc/shared/gcTrace.hpp"
35 #include "gc/shared/gcTraceTime.hpp"
36 #include "gc/shared/genCollectedHeap.hpp"
37 #include "gc/shared/genOopClosures.inline.hpp"
38 #include "gc/shared/generationSpec.hpp"
39 #include "gc/shared/space.hpp"
40 #include "gc/shared/strongRootsScope.hpp"
41 #include "gc/shared/vmGCOperations.hpp"
42 #include "gc/shared/workgroup.hpp"
43 #include "memory/filemap.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "oops/oop.inline.hpp"
46 #include "runtime/biasedLocking.hpp"
47 #include "runtime/fprofiler.hpp"
48 #include "runtime/handles.hpp"
49 #include "runtime/handles.inline.hpp"
50 #include "runtime/java.hpp"
51 #include "runtime/vmThread.hpp"
52 #include "services/management.hpp"
53 #include "services/memoryService.hpp"
54 #include "utilities/macros.hpp"
55 #include "utilities/stack.inline.hpp"
56 #include "utilities/vmError.hpp"
57 #if INCLUDE_ALL_GCS
58 #include "gc/cms/concurrentMarkSweepThread.hpp"
59 #include "gc/cms/vmCMSOperations.hpp"
60 #endif // INCLUDE_ALL_GCS
61
62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
63
64 // The set of potentially parallel tasks in root scanning.
65 enum GCH_strong_roots_tasks {
66 GCH_PS_Universe_oops_do,
67 GCH_PS_JNIHandles_oops_do,
68 GCH_PS_ObjectSynchronizer_oops_do,
69 GCH_PS_FlatProfiler_oops_do,
70 GCH_PS_Management_oops_do,
71 GCH_PS_SystemDictionary_oops_do,
72 GCH_PS_ClassLoaderDataGraph_oops_do,
73 GCH_PS_jvmti_oops_do,
74 GCH_PS_CodeCache_oops_do,
75 GCH_PS_younger_gens,
76 // Leave this one last.
77 GCH_PS_NumElements
78 };
79
80 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
81 CollectedHeap(),
82 _rem_set(NULL),
83 _gen_policy(policy),
84 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
85 _full_collections_completed(0)
86 {
87 assert(policy != NULL, "Sanity check");
88 if (UseConcMarkSweepGC) {
89 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
90 /* are_GC_task_threads */true,
91 /* are_ConcurrentGC_threads */false);
92 _workers->initialize_workers();
93 } else {
94 // Serial GC does not use workers.
95 _workers = NULL;
96 }
97 }
98
99 jint GenCollectedHeap::initialize() {
100 CollectedHeap::pre_initialize();
101
102 // While there are no constraints in the GC code that HeapWordSize
103 // be any particular value, there are multiple other areas in the
104 // system which believe this to be true (e.g. oop->object_size in some
105 // cases incorrectly returns the size in wordSize units rather than
106 // HeapWordSize).
107 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
108
109 // Allocate space for the heap.
110
111 char* heap_address;
112 ReservedSpace heap_rs;
113
114 size_t heap_alignment = collector_policy()->heap_alignment();
115
116 heap_address = allocate(heap_alignment, &heap_rs);
117
118 if (!heap_rs.is_reserved()) {
119 vm_shutdown_during_initialization(
120 "Could not reserve enough space for object heap");
121 return JNI_ENOMEM;
122 }
123
124 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
125
126 _rem_set = collector_policy()->create_rem_set(reserved_region());
127 set_barrier_set(rem_set()->bs());
128
129 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
130 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
131 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
132
133 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
134 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
135 clear_incremental_collection_failed();
136
137 #if INCLUDE_ALL_GCS
138 // If we are running CMS, create the collector responsible
139 // for collecting the CMS generations.
140 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
141 bool success = create_cms_collector();
142 if (!success) return JNI_ENOMEM;
143 }
144 #endif // INCLUDE_ALL_GCS
145
146 return JNI_OK;
147 }
148
149 char* GenCollectedHeap::allocate(size_t alignment,
150 ReservedSpace* heap_rs){
151 // Now figure out the total size.
152 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
153 assert(alignment % pageSize == 0, "Must be");
154
155 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
156 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
157
158 // Check for overflow.
159 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
160 if (total_reserved < young_spec->max_size()) {
161 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
162 "the maximum representable size");
163 }
164 assert(total_reserved % alignment == 0,
165 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
166 SIZE_FORMAT, total_reserved, alignment));
167
168 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
169 return heap_rs->base();
170 }
171
172 void GenCollectedHeap::post_initialize() {
173 CollectedHeap::post_initialize();
174 ref_processing_init();
175 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
176 guarantee(policy->is_generation_policy(), "Illegal policy type");
177 assert((_young_gen->kind() == Generation::DefNew) ||
178 (_young_gen->kind() == Generation::ParNew),
179 "Wrong youngest generation type");
180 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
181
182 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
183 _old_gen->kind() == Generation::MarkSweepCompact,
184 "Wrong generation kind");
185
186 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
187 _old_gen->capacity(),
188 def_new_gen->from()->capacity());
189 policy->initialize_gc_policy_counters();
190 }
191
192 void GenCollectedHeap::ref_processing_init() {
193 _young_gen->ref_processor_init();
194 _old_gen->ref_processor_init();
195 }
196
197 size_t GenCollectedHeap::capacity() const {
198 return _young_gen->capacity() + _old_gen->capacity();
199 }
200
201 size_t GenCollectedHeap::used() const {
202 return _young_gen->used() + _old_gen->used();
203 }
204
205 void GenCollectedHeap::save_used_regions() {
206 _old_gen->save_used_region();
207 _young_gen->save_used_region();
208 }
209
210 size_t GenCollectedHeap::max_capacity() const {
211 return _young_gen->max_capacity() + _old_gen->max_capacity();
212 }
213
214 // Update the _full_collections_completed counter
215 // at the end of a stop-world full GC.
216 unsigned int GenCollectedHeap::update_full_collections_completed() {
217 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
218 assert(_full_collections_completed <= _total_full_collections,
219 "Can't complete more collections than were started");
220 _full_collections_completed = _total_full_collections;
221 ml.notify_all();
222 return _full_collections_completed;
223 }
224
225 // Update the _full_collections_completed counter, as appropriate,
226 // at the end of a concurrent GC cycle. Note the conditional update
227 // below to allow this method to be called by a concurrent collector
228 // without synchronizing in any manner with the VM thread (which
229 // may already have initiated a STW full collection "concurrently").
230 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
231 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
232 assert((_full_collections_completed <= _total_full_collections) &&
233 (count <= _total_full_collections),
234 "Can't complete more collections than were started");
235 if (count > _full_collections_completed) {
236 _full_collections_completed = count;
237 ml.notify_all();
238 }
239 return _full_collections_completed;
240 }
241
242
243 #ifndef PRODUCT
244 // Override of memory state checking method in CollectedHeap:
245 // Some collectors (CMS for example) can't have badHeapWordVal written
246 // in the first two words of an object. (For instance , in the case of
247 // CMS these words hold state used to synchronize between certain
248 // (concurrent) GC steps and direct allocating mutators.)
249 // The skip_header_HeapWords() method below, allows us to skip
250 // over the requisite number of HeapWord's. Note that (for
251 // generational collectors) this means that those many words are
252 // skipped in each object, irrespective of the generation in which
253 // that object lives. The resultant loss of precision seems to be
254 // harmless and the pain of avoiding that imprecision appears somewhat
255 // higher than we are prepared to pay for such rudimentary debugging
256 // support.
257 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
258 size_t size) {
259 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
260 // We are asked to check a size in HeapWords,
261 // but the memory is mangled in juint words.
262 juint* start = (juint*) (addr + skip_header_HeapWords());
263 juint* end = (juint*) (addr + size);
264 for (juint* slot = start; slot < end; slot += 1) {
265 assert(*slot == badHeapWordVal,
266 "Found non badHeapWordValue in pre-allocation check");
267 }
268 }
269 }
270 #endif
271
272 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
273 bool is_tlab,
274 bool first_only) {
275 HeapWord* res = NULL;
276
277 if (_young_gen->should_allocate(size, is_tlab)) {
278 res = _young_gen->allocate(size, is_tlab);
279 if (res != NULL || first_only) {
280 return res;
281 }
282 }
283
284 if (_old_gen->should_allocate(size, is_tlab)) {
285 res = _old_gen->allocate(size, is_tlab);
286 }
287
288 return res;
289 }
290
291 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
292 bool* gc_overhead_limit_was_exceeded) {
293 return collector_policy()->mem_allocate_work(size,
294 false /* is_tlab */,
295 gc_overhead_limit_was_exceeded);
296 }
297
298 bool GenCollectedHeap::must_clear_all_soft_refs() {
299 return _gc_cause == GCCause::_last_ditch_collection;
300 }
301
302 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
303 if (!UseConcMarkSweepGC) {
304 return false;
305 }
306
307 switch (cause) {
308 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
309 case GCCause::_java_lang_system_gc:
310 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
311 default: return false;
312 }
313 }
314
315 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
316 bool is_tlab, bool run_verification, bool clear_soft_refs,
317 bool restore_marks_for_biased_locking) {
318 // Timer for individual generations. Last argument is false: no CR
319 // FIXME: We should try to start the timing earlier to cover more of the GC pause
320 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
321 // so we can assume here that the next GC id is what we want.
322 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
323 TraceCollectorStats tcs(gen->counters());
324 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
325
326 size_t prev_used = gen->used();
327 gen->stat_record()->invocations++;
328 gen->stat_record()->accumulated_time.start();
329
330 // Must be done anew before each collection because
331 // a previous collection will do mangling and will
332 // change top of some spaces.
333 record_gen_tops_before_GC();
334
335 if (PrintGC && Verbose) {
336 // I didn't want to change the logging when removing the level concept,
337 // but I guess this logging could say young/old or something instead of 0/1.
338 uint level;
339 if (heap()->is_young_gen(gen)) {
340 level = 0;
341 } else {
342 level = 1;
343 }
344 gclog_or_tty->print("level=%u invoke=%d size=" SIZE_FORMAT,
345 level,
346 gen->stat_record()->invocations,
347 size * HeapWordSize);
348 }
349
350 if (run_verification && VerifyBeforeGC) {
351 HandleMark hm; // Discard invalid handles created during verification
352 Universe::verify(" VerifyBeforeGC:");
353 }
354 COMPILER2_PRESENT(DerivedPointerTable::clear());
355
356 if (restore_marks_for_biased_locking) {
357 // We perform this mark word preservation work lazily
358 // because it's only at this point that we know whether we
359 // absolutely have to do it; we want to avoid doing it for
360 // scavenge-only collections where it's unnecessary
361 BiasedLocking::preserve_marks();
362 }
363
364 // Do collection work
365 {
366 // Note on ref discovery: For what appear to be historical reasons,
367 // GCH enables and disabled (by enqueing) refs discovery.
368 // In the future this should be moved into the generation's
369 // collect method so that ref discovery and enqueueing concerns
370 // are local to a generation. The collect method could return
371 // an appropriate indication in the case that notification on
372 // the ref lock was needed. This will make the treatment of
373 // weak refs more uniform (and indeed remove such concerns
374 // from GCH). XXX
375
376 HandleMark hm; // Discard invalid handles created during gc
377 save_marks(); // save marks for all gens
378 // We want to discover references, but not process them yet.
379 // This mode is disabled in process_discovered_references if the
380 // generation does some collection work, or in
381 // enqueue_discovered_references if the generation returns
382 // without doing any work.
383 ReferenceProcessor* rp = gen->ref_processor();
384 // If the discovery of ("weak") refs in this generation is
385 // atomic wrt other collectors in this configuration, we
386 // are guaranteed to have empty discovered ref lists.
387 if (rp->discovery_is_atomic()) {
388 rp->enable_discovery();
389 rp->setup_policy(clear_soft_refs);
390 } else {
391 // collect() below will enable discovery as appropriate
392 }
393 gen->collect(full, clear_soft_refs, size, is_tlab);
394 if (!rp->enqueuing_is_done()) {
395 rp->enqueue_discovered_references();
396 } else {
397 rp->set_enqueuing_is_done(false);
398 }
399 rp->verify_no_references_recorded();
400 }
401
402 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
403
404 gen->stat_record()->accumulated_time.stop();
405
406 update_gc_stats(gen, full);
407
408 if (run_verification && VerifyAfterGC) {
409 HandleMark hm; // Discard invalid handles created during verification
410 Universe::verify(" VerifyAfterGC:");
411 }
412
413 if (PrintGCDetails) {
414 gclog_or_tty->print(":");
415 gen->print_heap_change(prev_used);
416 }
417 }
418
419 void GenCollectedHeap::do_collection(bool full,
420 bool clear_all_soft_refs,
421 size_t size,
422 bool is_tlab,
423 GenerationType max_generation) {
424 ResourceMark rm;
425 DEBUG_ONLY(Thread* my_thread = Thread::current();)
426
427 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
428 assert(my_thread->is_VM_thread() ||
429 my_thread->is_ConcurrentGC_thread(),
430 "incorrect thread type capability");
431 assert(Heap_lock->is_locked(),
432 "the requesting thread should have the Heap_lock");
433 guarantee(!is_gc_active(), "collection is not reentrant");
434
435 if (GC_locker::check_active_before_gc()) {
436 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
437 }
438
439 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
440 collector_policy()->should_clear_all_soft_refs();
441
442 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
443
444 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
445
446 print_heap_before_gc();
447
448 {
449 FlagSetting fl(_is_gc_active, true);
450
451 bool complete = full && (max_generation == OldGen);
452 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
453 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
454 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
455 // so we can assume here that the next GC id is what we want.
456 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
457
458 gc_prologue(complete);
459 increment_total_collections(complete);
460
461 size_t gch_prev_used = used();
462 bool run_verification = total_collections() >= VerifyGCStartAt;
463
464 bool prepared_for_verification = false;
465 bool collected_old = false;
466 bool old_collects_young = complete &&
467 _old_gen->full_collects_younger_generations();
468 if (!old_collects_young &&
469 _young_gen->should_collect(full, size, is_tlab)) {
470 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
471 prepare_for_verify();
472 prepared_for_verification = true;
473 }
474
475 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
476 collect_generation(_young_gen,
477 full,
478 size,
479 is_tlab,
480 run_verification && VerifyGCLevel <= 0,
481 do_clear_all_soft_refs,
482 false);
483
484 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
485 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
486 // Allocation request was met by young GC.
487 size = 0;
488 }
489 }
490
491 bool must_restore_marks_for_biased_locking = false;
492
493 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
494 if (!complete) {
495 // The full_collections increment was missed above.
496 increment_total_full_collections();
497 }
498
499 pre_full_gc_dump(NULL); // do any pre full gc dumps
500
501 if (!prepared_for_verification && run_verification &&
502 VerifyGCLevel <= 1 && VerifyBeforeGC) {
503 prepare_for_verify();
504 }
505
506 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
507 collect_generation(_old_gen,
508 full,
509 size,
510 is_tlab,
511 run_verification && VerifyGCLevel <= 1,
512 do_clear_all_soft_refs,
513 true);
514
515 must_restore_marks_for_biased_locking = true;
516 collected_old = true;
517 }
518
519 // Update "complete" boolean wrt what actually transpired --
520 // for instance, a promotion failure could have led to
521 // a whole heap collection.
522 complete = complete || collected_old;
523
524 if (complete) { // We did a "major" collection
525 // FIXME: See comment at pre_full_gc_dump call
526 post_full_gc_dump(NULL); // do any post full gc dumps
527 }
528
529 if (PrintGCDetails) {
530 print_heap_change(gch_prev_used);
531
532 // Print metaspace info for full GC with PrintGCDetails flag.
533 if (complete) {
534 MetaspaceAux::print_metaspace_change(metadata_prev_used);
535 }
536 }
537
538 // Adjust generation sizes.
539 if (collected_old) {
540 _old_gen->compute_new_size();
541 }
542 _young_gen->compute_new_size();
543
544 if (complete) {
545 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
546 ClassLoaderDataGraph::purge();
547 MetaspaceAux::verify_metrics();
548 // Resize the metaspace capacity after full collections
549 MetaspaceGC::compute_new_size();
550 update_full_collections_completed();
551 }
552
553 // Track memory usage and detect low memory after GC finishes
554 MemoryService::track_memory_usage();
555
556 gc_epilogue(complete);
557
558 if (must_restore_marks_for_biased_locking) {
559 BiasedLocking::restore_marks();
560 }
561 }
562
563 print_heap_after_gc();
564
565 #ifdef TRACESPINNING
566 ParallelTaskTerminator::print_termination_counts();
567 #endif
568 }
569
570 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
571 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
572 }
573
574 #ifdef ASSERT
575 class AssertNonScavengableClosure: public OopClosure {
576 public:
577 virtual void do_oop(oop* p) {
578 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
579 "Referent should not be scavengable."); }
580 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
581 };
582 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
583 #endif
584
585 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
586 ScanningOption so,
587 OopClosure* strong_roots,
588 OopClosure* weak_roots,
589 CLDClosure* strong_cld_closure,
590 CLDClosure* weak_cld_closure,
591 CodeBlobClosure* code_roots) {
592 // General roots.
593 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
594 assert(code_roots != NULL, "code root closure should always be set");
595 // _n_termination for _process_strong_tasks should be set up stream
596 // in a method not running in a GC worker. Otherwise the GC worker
597 // could be trying to change the termination condition while the task
598 // is executing in another GC worker.
599
600 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
601 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
602 }
603
604 // Some CLDs contained in the thread frames should be considered strong.
605 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
606 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
607 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
608 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
609
610 bool is_par = scope->n_threads() > 1;
611 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
612
613 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
614 Universe::oops_do(strong_roots);
615 }
616 // Global (strong) JNI handles
617 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
618 JNIHandles::oops_do(strong_roots);
619 }
620
621 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
622 ObjectSynchronizer::oops_do(strong_roots);
623 }
624 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
625 FlatProfiler::oops_do(strong_roots);
626 }
627 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
628 Management::oops_do(strong_roots);
629 }
630 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
631 JvmtiExport::oops_do(strong_roots);
632 }
633
634 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
635 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
636 }
637
638 // All threads execute the following. A specific chunk of buckets
639 // from the StringTable are the individual tasks.
640 if (weak_roots != NULL) {
641 if (is_par) {
642 StringTable::possibly_parallel_oops_do(weak_roots);
643 } else {
644 StringTable::oops_do(weak_roots);
645 }
646 }
647
648 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
649 if (so & SO_ScavengeCodeCache) {
650 assert(code_roots != NULL, "must supply closure for code cache");
651
652 // We only visit parts of the CodeCache when scavenging.
653 CodeCache::scavenge_root_nmethods_do(code_roots);
654 }
655 if (so & SO_AllCodeCache) {
656 assert(code_roots != NULL, "must supply closure for code cache");
657
658 // CMSCollector uses this to do intermediate-strength collections.
659 // We scan the entire code cache, since CodeCache::do_unloading is not called.
660 CodeCache::blobs_do(code_roots);
661 }
662 // Verify that the code cache contents are not subject to
663 // movement by a scavenging collection.
664 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
665 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
666 }
667 }
668
669 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
670 GenerationType type,
671 bool younger_gens_as_roots,
672 ScanningOption so,
673 bool only_strong_roots,
674 OopsInGenClosure* not_older_gens,
675 OopsInGenClosure* older_gens,
676 CLDClosure* cld_closure) {
677 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
678
679 bool is_moving_collection = false;
680 if (type == YoungGen || is_adjust_phase) {
681 // young collections are always moving
682 is_moving_collection = true;
683 }
684
685 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
686 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
687 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
688
689 process_roots(scope, so,
690 not_older_gens, weak_roots,
691 cld_closure, weak_cld_closure,
692 &mark_code_closure);
693
694 if (younger_gens_as_roots) {
695 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
696 if (type == OldGen) {
697 not_older_gens->set_generation(_young_gen);
698 _young_gen->oop_iterate(not_older_gens);
699 }
700 not_older_gens->reset_generation();
701 }
702 }
703 // When collection is parallel, all threads get to cooperate to do
704 // old generation scanning.
705 if (type == YoungGen) {
706 older_gens->set_generation(_old_gen);
707 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
708 older_gens->reset_generation();
709 }
710
711 _process_strong_tasks->all_tasks_completed(scope->n_threads());
712 }
713
714
715 class AlwaysTrueClosure: public BoolObjectClosure {
716 public:
717 bool do_object_b(oop p) { return true; }
718 };
719 static AlwaysTrueClosure always_true;
720
721 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
722 JNIHandles::weak_oops_do(&always_true, root_closure);
723 _young_gen->ref_processor()->weak_oops_do(root_closure);
724 _old_gen->ref_processor()->weak_oops_do(root_closure);
725 }
726
727 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
728 void GenCollectedHeap:: \
729 oop_since_save_marks_iterate(GenerationType gen, \
730 OopClosureType* cur, \
731 OopClosureType* older) { \
732 if (gen == YoungGen) { \
733 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
734 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
735 } else { \
736 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
737 } \
738 }
739
740 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
741
742 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
743
744 bool GenCollectedHeap::no_allocs_since_save_marks(bool include_young) {
745 if (include_young && !_young_gen->no_allocs_since_save_marks()) {
746 return false;
747 }
748 return _old_gen->no_allocs_since_save_marks();
749 }
750
751 bool GenCollectedHeap::supports_inline_contig_alloc() const {
752 return _young_gen->supports_inline_contig_alloc();
753 }
754
755 HeapWord** GenCollectedHeap::top_addr() const {
756 return _young_gen->top_addr();
757 }
758
759 HeapWord** GenCollectedHeap::end_addr() const {
760 return _young_gen->end_addr();
761 }
762
763 // public collection interfaces
764
765 void GenCollectedHeap::collect(GCCause::Cause cause) {
766 if (should_do_concurrent_full_gc(cause)) {
767 #if INCLUDE_ALL_GCS
768 // mostly concurrent full collection
769 collect_mostly_concurrent(cause);
770 #else // INCLUDE_ALL_GCS
771 ShouldNotReachHere();
772 #endif // INCLUDE_ALL_GCS
773 } else if (cause == GCCause::_wb_young_gc) {
774 // minor collection for WhiteBox API
775 collect(cause, YoungGen);
776 } else {
777 #ifdef ASSERT
778 if (cause == GCCause::_scavenge_alot) {
779 // minor collection only
780 collect(cause, YoungGen);
781 } else {
782 // Stop-the-world full collection
783 collect(cause, OldGen);
784 }
785 #else
786 // Stop-the-world full collection
787 collect(cause, OldGen);
788 #endif
789 }
790 }
791
792 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
793 // The caller doesn't have the Heap_lock
794 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
795 MutexLocker ml(Heap_lock);
796 collect_locked(cause, max_generation);
797 }
798
799 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
800 // The caller has the Heap_lock
801 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
802 collect_locked(cause, OldGen);
803 }
804
805 // this is the private collection interface
806 // The Heap_lock is expected to be held on entry.
807
808 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
809 // Read the GC count while holding the Heap_lock
810 unsigned int gc_count_before = total_collections();
811 unsigned int full_gc_count_before = total_full_collections();
812 {
813 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
814 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
815 cause, max_generation);
816 VMThread::execute(&op);
817 }
818 }
819
820 #if INCLUDE_ALL_GCS
821 bool GenCollectedHeap::create_cms_collector() {
822
823 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
824 "Unexpected generation kinds");
825 // Skip two header words in the block content verification
826 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
827 CMSCollector* collector = new CMSCollector(
828 (ConcurrentMarkSweepGeneration*)_old_gen,
829 _rem_set->as_CardTableRS(),
830 (ConcurrentMarkSweepPolicy*) collector_policy());
831
832 if (collector == NULL || !collector->completed_initialization()) {
833 if (collector) {
834 delete collector; // Be nice in embedded situation
835 }
836 vm_shutdown_during_initialization("Could not create CMS collector");
837 return false;
838 }
839 return true; // success
840 }
841
842 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
843 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
844
845 MutexLocker ml(Heap_lock);
846 // Read the GC counts while holding the Heap_lock
847 unsigned int full_gc_count_before = total_full_collections();
848 unsigned int gc_count_before = total_collections();
849 {
850 MutexUnlocker mu(Heap_lock);
851 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
852 VMThread::execute(&op);
853 }
854 }
855 #endif // INCLUDE_ALL_GCS
856
857 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
858 do_full_collection(clear_all_soft_refs, OldGen);
859 }
860
861 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
862 GenerationType last_generation) {
863 GenerationType local_last_generation;
864 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
865 gc_cause() == GCCause::_gc_locker) {
866 local_last_generation = YoungGen;
867 } else {
868 local_last_generation = last_generation;
869 }
870
871 do_collection(true, // full
872 clear_all_soft_refs, // clear_all_soft_refs
873 0, // size
874 false, // is_tlab
875 local_last_generation); // last_generation
876 // Hack XXX FIX ME !!!
877 // A scavenge may not have been attempted, or may have
878 // been attempted and failed, because the old gen was too full
879 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
880 incremental_collection_will_fail(false /* don't consult_young */)) {
881 if (PrintGCDetails) {
882 gclog_or_tty->print_cr("GC locker: Trying a full collection "
883 "because scavenge failed");
884 }
885 // This time allow the old gen to be collected as well
886 do_collection(true, // full
887 clear_all_soft_refs, // clear_all_soft_refs
888 0, // size
889 false, // is_tlab
890 OldGen); // last_generation
891 }
892 }
893
894 bool GenCollectedHeap::is_in_young(oop p) {
895 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
896 assert(result == _young_gen->is_in_reserved(p),
897 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
898 return result;
899 }
900
901 // Returns "TRUE" iff "p" points into the committed areas of the heap.
902 bool GenCollectedHeap::is_in(const void* p) const {
903 return _young_gen->is_in(p) || _old_gen->is_in(p);
904 }
905
906 #ifdef ASSERT
907 // Don't implement this by using is_in_young(). This method is used
908 // in some cases to check that is_in_young() is correct.
909 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
910 assert(is_in_reserved(p) || p == NULL,
911 "Does not work if address is non-null and outside of the heap");
912 return p < _young_gen->reserved().end() && p != NULL;
913 }
914 #endif
915
916 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
917 NoHeaderExtendedOopClosure no_header_cl(cl);
918 oop_iterate(&no_header_cl);
919 }
920
921 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
922 _young_gen->oop_iterate(cl);
923 _old_gen->oop_iterate(cl);
924 }
925
926 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
927 _young_gen->object_iterate(cl);
928 _old_gen->object_iterate(cl);
929 }
930
931 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
932 _young_gen->safe_object_iterate(cl);
933 _old_gen->safe_object_iterate(cl);
934 }
935
936 Space* GenCollectedHeap::space_containing(const void* addr) const {
937 Space* res = _young_gen->space_containing(addr);
938 if (res != NULL) {
939 return res;
940 }
941 res = _old_gen->space_containing(addr);
942 assert(res != NULL, "Could not find containing space");
943 return res;
944 }
945
946 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
947 assert(is_in_reserved(addr), "block_start of address outside of heap");
948 if (_young_gen->is_in_reserved(addr)) {
949 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
950 return _young_gen->block_start(addr);
951 }
952
953 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
954 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
955 return _old_gen->block_start(addr);
956 }
957
958 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
959 assert(is_in_reserved(addr), "block_size of address outside of heap");
960 if (_young_gen->is_in_reserved(addr)) {
961 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
962 return _young_gen->block_size(addr);
963 }
964
965 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
966 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
967 return _old_gen->block_size(addr);
968 }
969
970 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
971 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
972 assert(block_start(addr) == addr, "addr must be a block start");
973 if (_young_gen->is_in_reserved(addr)) {
974 return _young_gen->block_is_obj(addr);
975 }
976
977 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
978 return _old_gen->block_is_obj(addr);
979 }
980
981 bool GenCollectedHeap::supports_tlab_allocation() const {
982 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
983 return _young_gen->supports_tlab_allocation();
984 }
985
986 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
987 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
988 if (_young_gen->supports_tlab_allocation()) {
989 return _young_gen->tlab_capacity();
990 }
991 return 0;
992 }
993
994 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
995 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
996 if (_young_gen->supports_tlab_allocation()) {
997 return _young_gen->tlab_used();
998 }
999 return 0;
1000 }
1001
1002 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1003 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1004 if (_young_gen->supports_tlab_allocation()) {
1005 return _young_gen->unsafe_max_tlab_alloc();
1006 }
1007 return 0;
1008 }
1009
1010 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1011 bool gc_overhead_limit_was_exceeded;
1012 return collector_policy()->mem_allocate_work(size /* size */,
1013 true /* is_tlab */,
1014 &gc_overhead_limit_was_exceeded);
1015 }
1016
1017 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1018 // from the list headed by "*prev_ptr".
1019 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1020 bool first = true;
1021 size_t min_size = 0; // "first" makes this conceptually infinite.
1022 ScratchBlock **smallest_ptr, *smallest;
1023 ScratchBlock *cur = *prev_ptr;
1024 while (cur) {
1025 assert(*prev_ptr == cur, "just checking");
1026 if (first || cur->num_words < min_size) {
1027 smallest_ptr = prev_ptr;
1028 smallest = cur;
1029 min_size = smallest->num_words;
1030 first = false;
1031 }
1032 prev_ptr = &cur->next;
1033 cur = cur->next;
1034 }
1035 smallest = *smallest_ptr;
1036 *smallest_ptr = smallest->next;
1037 return smallest;
1038 }
1039
1040 // Sort the scratch block list headed by res into decreasing size order,
1041 // and set "res" to the result.
1042 static void sort_scratch_list(ScratchBlock*& list) {
1043 ScratchBlock* sorted = NULL;
1044 ScratchBlock* unsorted = list;
1045 while (unsorted) {
1046 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1047 smallest->next = sorted;
1048 sorted = smallest;
1049 }
1050 list = sorted;
1051 }
1052
1053 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1054 size_t max_alloc_words) {
1055 ScratchBlock* res = NULL;
1056 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1057 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1058 sort_scratch_list(res);
1059 return res;
1060 }
1061
1062 void GenCollectedHeap::release_scratch() {
1063 _young_gen->reset_scratch();
1064 _old_gen->reset_scratch();
1065 }
1066
1067 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1068 void do_generation(Generation* gen) {
1069 gen->prepare_for_verify();
1070 }
1071 };
1072
1073 void GenCollectedHeap::prepare_for_verify() {
1074 ensure_parsability(false); // no need to retire TLABs
1075 GenPrepareForVerifyClosure blk;
1076 generation_iterate(&blk, false);
1077 }
1078
1079 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1080 bool old_to_young) {
1081 if (old_to_young) {
1082 cl->do_generation(_old_gen);
1083 cl->do_generation(_young_gen);
1084 } else {
1085 cl->do_generation(_young_gen);
1086 cl->do_generation(_old_gen);
1087 }
1088 }
1089
1090 bool GenCollectedHeap::is_maximal_no_gc() const {
1091 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1092 }
1093
1094 void GenCollectedHeap::save_marks() {
1095 _young_gen->save_marks();
1096 _old_gen->save_marks();
1097 }
1098
1099 GenCollectedHeap* GenCollectedHeap::heap() {
1100 CollectedHeap* heap = Universe::heap();
1101 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1102 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1103 return (GenCollectedHeap*)heap;
1104 }
1105
1106 void GenCollectedHeap::prepare_for_compaction() {
1107 // Start by compacting into same gen.
1108 CompactPoint cp(_old_gen);
1109 _old_gen->prepare_for_compaction(&cp);
1110 _young_gen->prepare_for_compaction(&cp);
1111 }
1112
1113 GCStats* GenCollectedHeap::gc_stats(Generation* gen) const {
1114 return gen->gc_stats();
1115 }
1116
1117 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1118 if (!silent) {
1119 gclog_or_tty->print("%s", _old_gen->name());
1120 gclog_or_tty->print(" ");
1121 }
1122 _old_gen->verify();
1123
1124 if (!silent) {
1125 gclog_or_tty->print("%s", _young_gen->name());
1126 gclog_or_tty->print(" ");
1127 }
1128 _young_gen->verify();
1129
1130 if (!silent) {
1131 gclog_or_tty->print("remset ");
1132 }
1133 rem_set()->verify();
1134 }
1135
1136 void GenCollectedHeap::print_on(outputStream* st) const {
1137 _young_gen->print_on(st);
1138 _old_gen->print_on(st);
1139 MetaspaceAux::print_on(st);
1140 }
1141
1142 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1143 if (workers() != NULL) {
1144 workers()->threads_do(tc);
1145 }
1146 #if INCLUDE_ALL_GCS
1147 if (UseConcMarkSweepGC) {
1148 ConcurrentMarkSweepThread::threads_do(tc);
1149 }
1150 #endif // INCLUDE_ALL_GCS
1151 }
1152
1153 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1154 #if INCLUDE_ALL_GCS
1155 if (UseConcMarkSweepGC) {
1156 workers()->print_worker_threads_on(st);
1157 ConcurrentMarkSweepThread::print_all_on(st);
1158 }
1159 #endif // INCLUDE_ALL_GCS
1160 }
1161
1162 void GenCollectedHeap::print_on_error(outputStream* st) const {
1163 this->CollectedHeap::print_on_error(st);
1164
1165 #if INCLUDE_ALL_GCS
1166 if (UseConcMarkSweepGC) {
1167 st->cr();
1168 CMSCollector::print_on_error(st);
1169 }
1170 #endif // INCLUDE_ALL_GCS
1171 }
1172
1173 void GenCollectedHeap::print_tracing_info() const {
1174 if (TraceYoungGenTime) {
1175 _young_gen->print_summary_info();
1176 }
1177 if (TraceOldGenTime) {
1178 _old_gen->print_summary_info();
1179 }
1180 }
1181
1182 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1183 if (PrintGCDetails && Verbose) {
1184 gclog_or_tty->print(" " SIZE_FORMAT
1185 "->" SIZE_FORMAT
1186 "(" SIZE_FORMAT ")",
1187 prev_used, used(), capacity());
1188 } else {
1189 gclog_or_tty->print(" " SIZE_FORMAT "K"
1190 "->" SIZE_FORMAT "K"
1191 "(" SIZE_FORMAT "K)",
1192 prev_used / K, used() / K, capacity() / K);
1193 }
1194 }
1195
1196 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1197 private:
1198 bool _full;
1199 public:
1200 void do_generation(Generation* gen) {
1201 gen->gc_prologue(_full);
1202 }
1203 GenGCPrologueClosure(bool full) : _full(full) {};
1204 };
1205
1206 void GenCollectedHeap::gc_prologue(bool full) {
1207 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1208
1209 always_do_update_barrier = false;
1210 // Fill TLAB's and such
1211 CollectedHeap::accumulate_statistics_all_tlabs();
1212 ensure_parsability(true); // retire TLABs
1213
1214 // Walk generations
1215 GenGCPrologueClosure blk(full);
1216 generation_iterate(&blk, false); // not old-to-young.
1217 };
1218
1219 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1220 private:
1221 bool _full;
1222 public:
1223 void do_generation(Generation* gen) {
1224 gen->gc_epilogue(_full);
1225 }
1226 GenGCEpilogueClosure(bool full) : _full(full) {};
1227 };
1228
1229 void GenCollectedHeap::gc_epilogue(bool full) {
1230 #ifdef COMPILER2
1231 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1232 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1233 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1234 #endif /* COMPILER2 */
1235
1236 resize_all_tlabs();
1237
1238 GenGCEpilogueClosure blk(full);
1239 generation_iterate(&blk, false); // not old-to-young.
1240
1241 if (!CleanChunkPoolAsync) {
1242 Chunk::clean_chunk_pool();
1243 }
1244
1245 MetaspaceCounters::update_performance_counters();
1246 CompressedClassSpaceCounters::update_performance_counters();
1247
1248 always_do_update_barrier = UseConcMarkSweepGC;
1249 };
1250
1251 #ifndef PRODUCT
1252 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1253 private:
1254 public:
1255 void do_generation(Generation* gen) {
1256 gen->record_spaces_top();
1257 }
1258 };
1259
1260 void GenCollectedHeap::record_gen_tops_before_GC() {
1261 if (ZapUnusedHeapArea) {
1262 GenGCSaveTopsBeforeGCClosure blk;
1263 generation_iterate(&blk, false); // not old-to-young.
1264 }
1265 }
1266 #endif // not PRODUCT
1267
1268 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1269 public:
1270 void do_generation(Generation* gen) {
1271 gen->ensure_parsability();
1272 }
1273 };
1274
1275 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1276 CollectedHeap::ensure_parsability(retire_tlabs);
1277 GenEnsureParsabilityClosure ep_cl;
1278 generation_iterate(&ep_cl, false);
1279 }
1280
1281 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1282 oop obj,
1283 size_t obj_size) {
1284 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1285 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1286 HeapWord* result = NULL;
1287
1288 result = old_gen->expand_and_allocate(obj_size, false);
1289
1290 if (result != NULL) {
1291 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1292 }
1293 return oop(result);
1294 }
1295
1296 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1297 jlong _time; // in ms
1298 jlong _now; // in ms
1299
1300 public:
1301 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1302
1303 jlong time() { return _time; }
1304
1305 void do_generation(Generation* gen) {
1306 _time = MIN2(_time, gen->time_of_last_gc(_now));
1307 }
1308 };
1309
1310 jlong GenCollectedHeap::millis_since_last_gc() {
1311 // We need a monotonically non-decreasing time in ms but
1312 // os::javaTimeMillis() does not guarantee monotonicity.
1313 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1314 GenTimeOfLastGCClosure tolgc_cl(now);
1315 // iterate over generations getting the oldest
1316 // time that a generation was collected
1317 generation_iterate(&tolgc_cl, false);
1318
1319 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1320 // provided the underlying platform provides such a time source
1321 // (and it is bug free). So we still have to guard against getting
1322 // back a time later than 'now'.
1323 jlong retVal = now - tolgc_cl.time();
1324 if (retVal < 0) {
1325 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1326 return 0;
1327 }
1328 return retVal;
1329 }