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_implementation/shared/collectorCounters.hpp"
32 #include "gc_implementation/shared/gcTrace.hpp"
33 #include "gc_implementation/shared/gcTraceTime.hpp"
34 #include "gc_implementation/shared/vmGCOperations.hpp"
35 #include "gc_interface/collectedHeap.inline.hpp"
36 #include "memory/filemap.hpp"
37 #include "memory/gcLocker.inline.hpp"
38 #include "memory/genCollectedHeap.hpp"
39 #include "memory/genOopClosures.inline.hpp"
40 #include "memory/generationSpec.hpp"
41 #include "memory/resourceArea.hpp"
42 #include "memory/sharedHeap.hpp"
43 #include "memory/space.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "runtime/biasedLocking.hpp"
46 #include "runtime/fprofiler.hpp"
47 #include "runtime/handles.hpp"
48 #include "runtime/handles.inline.hpp"
49 #include "runtime/java.hpp"
50 #include "runtime/vmThread.hpp"
51 #include "services/management.hpp"
52 #include "services/memoryService.hpp"
53 #include "utilities/vmError.hpp"
54 #include "utilities/workgroup.hpp"
55 #include "utilities/macros.hpp"
56 #if INCLUDE_ALL_GCS
57 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
58 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
59 #endif // INCLUDE_ALL_GCS
60
61 GenCollectedHeap* GenCollectedHeap::_gch;
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 SharedHeap(),
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 }
89
90 jint GenCollectedHeap::initialize() {
91 CollectedHeap::pre_initialize();
92
93 _n_gens = gen_policy()->number_of_generations();
94 assert(_n_gens == 2, "There is no support for more than two generations");
95
96 // While there are no constraints in the GC code that HeapWordSize
97 // be any particular value, there are multiple other areas in the
98 // system which believe this to be true (e.g. oop->object_size in some
99 // cases incorrectly returns the size in wordSize units rather than
100 // HeapWordSize).
101 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
102
103 // Allocate space for the heap.
104
105 char* heap_address;
106 ReservedSpace heap_rs;
107
108 size_t heap_alignment = collector_policy()->heap_alignment();
109
110 heap_address = allocate(heap_alignment, &heap_rs);
111
112 if (!heap_rs.is_reserved()) {
113 vm_shutdown_during_initialization(
114 "Could not reserve enough space for object heap");
115 return JNI_ENOMEM;
116 }
117
118 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
119
120 _rem_set = collector_policy()->create_rem_set(reserved_region());
121 set_barrier_set(rem_set()->bs());
122
123 _gch = this;
124
125 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
126 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set());
127 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
128
129 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
130 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set());
131 clear_incremental_collection_failed();
132
133 #if INCLUDE_ALL_GCS
134 // If we are running CMS, create the collector responsible
135 // for collecting the CMS generations.
136 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
137 bool success = create_cms_collector();
138 if (!success) return JNI_ENOMEM;
139 }
140 #endif // INCLUDE_ALL_GCS
141
142 return JNI_OK;
143 }
144
145 char* GenCollectedHeap::allocate(size_t alignment,
146 ReservedSpace* heap_rs){
147 // Now figure out the total size.
148 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
149 assert(alignment % pageSize == 0, "Must be");
150
151 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
152 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
153
154 // Check for overflow.
155 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
156 if (total_reserved < young_spec->max_size()) {
157 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
158 "the maximum representable size");
159 }
160 assert(total_reserved % alignment == 0,
161 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
162 SIZE_FORMAT, total_reserved, alignment));
163
164 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
165 return heap_rs->base();
166 }
167
168 void GenCollectedHeap::post_initialize() {
169 SharedHeap::post_initialize();
170 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
171 guarantee(policy->is_generation_policy(), "Illegal policy type");
172 assert((_young_gen->kind() == Generation::DefNew) ||
173 (_young_gen->kind() == Generation::ParNew),
174 "Wrong youngest generation type");
175 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
176
177 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
178 _old_gen->kind() == Generation::MarkSweepCompact,
179 "Wrong generation kind");
180
181 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
182 _old_gen->capacity(),
183 def_new_gen->from()->capacity());
184 policy->initialize_gc_policy_counters();
185 }
186
187 void GenCollectedHeap::ref_processing_init() {
188 SharedHeap::ref_processing_init();
189 _young_gen->ref_processor_init();
190 _old_gen->ref_processor_init();
191 }
192
193 size_t GenCollectedHeap::capacity() const {
194 return _young_gen->capacity() + _old_gen->capacity();
195 }
196
197 size_t GenCollectedHeap::used() const {
198 return _young_gen->used() + _old_gen->used();
199 }
200
201 // Save the "used_region" for generations level and lower.
202 void GenCollectedHeap::save_used_regions(int level) {
203 assert(level >= 0, "Illegal level parameter");
204 assert(level < _n_gens, "Illegal level parameter");
205 if (level == 1) {
206 _old_gen->save_used_region();
207 }
208 _young_gen->save_used_region();
209 }
210
211 size_t GenCollectedHeap::max_capacity() const {
212 return _young_gen->max_capacity() + _old_gen->max_capacity();
213 }
214
215 // Update the _full_collections_completed counter
216 // at the end of a stop-world full GC.
217 unsigned int GenCollectedHeap::update_full_collections_completed() {
218 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
219 assert(_full_collections_completed <= _total_full_collections,
220 "Can't complete more collections than were started");
221 _full_collections_completed = _total_full_collections;
222 ml.notify_all();
223 return _full_collections_completed;
224 }
225
226 // Update the _full_collections_completed counter, as appropriate,
227 // at the end of a concurrent GC cycle. Note the conditional update
228 // below to allow this method to be called by a concurrent collector
229 // without synchronizing in any manner with the VM thread (which
230 // may already have initiated a STW full collection "concurrently").
231 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
232 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
233 assert((_full_collections_completed <= _total_full_collections) &&
234 (count <= _total_full_collections),
235 "Can't complete more collections than were started");
236 if (count > _full_collections_completed) {
237 _full_collections_completed = count;
238 ml.notify_all();
239 }
240 return _full_collections_completed;
241 }
242
243
244 #ifndef PRODUCT
245 // Override of memory state checking method in CollectedHeap:
246 // Some collectors (CMS for example) can't have badHeapWordVal written
247 // in the first two words of an object. (For instance , in the case of
248 // CMS these words hold state used to synchronize between certain
249 // (concurrent) GC steps and direct allocating mutators.)
250 // The skip_header_HeapWords() method below, allows us to skip
251 // over the requisite number of HeapWord's. Note that (for
252 // generational collectors) this means that those many words are
253 // skipped in each object, irrespective of the generation in which
254 // that object lives. The resultant loss of precision seems to be
255 // harmless and the pain of avoiding that imprecision appears somewhat
256 // higher than we are prepared to pay for such rudimentary debugging
257 // support.
258 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
259 size_t size) {
260 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
261 // We are asked to check a size in HeapWords,
262 // but the memory is mangled in juint words.
263 juint* start = (juint*) (addr + skip_header_HeapWords());
264 juint* end = (juint*) (addr + size);
265 for (juint* slot = start; slot < end; slot += 1) {
266 assert(*slot == badHeapWordVal,
267 "Found non badHeapWordValue in pre-allocation check");
268 }
269 }
270 }
271 #endif
272
273 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
274 bool is_tlab,
275 bool first_only) {
276 HeapWord* res = NULL;
277
278 if (_young_gen->should_allocate(size, is_tlab)) {
279 res = _young_gen->allocate(size, is_tlab);
280 if (res != NULL || first_only) {
281 return res;
282 }
283 }
284
285 if (_old_gen->should_allocate(size, is_tlab)) {
286 res = _old_gen->allocate(size, is_tlab);
287 }
288
289 return res;
290 }
291
292 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
293 bool* gc_overhead_limit_was_exceeded) {
294 return collector_policy()->mem_allocate_work(size,
295 false /* is_tlab */,
296 gc_overhead_limit_was_exceeded);
297 }
298
299 bool GenCollectedHeap::must_clear_all_soft_refs() {
300 return _gc_cause == GCCause::_last_ditch_collection;
301 }
302
303 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
304 return UseConcMarkSweepGC &&
305 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
306 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
307 }
308
309 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
310 bool is_tlab, bool run_verification, bool clear_soft_refs,
311 bool restore_marks_for_biased_locking) {
312 // Timer for individual generations. Last argument is false: no CR
313 // FIXME: We should try to start the timing earlier to cover more of the GC pause
314 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
315 // so we can assume here that the next GC id is what we want.
316 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
317 TraceCollectorStats tcs(gen->counters());
318 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
319
320 size_t prev_used = gen->used();
321 gen->stat_record()->invocations++;
322 gen->stat_record()->accumulated_time.start();
323
324 // Must be done anew before each collection because
325 // a previous collection will do mangling and will
326 // change top of some spaces.
327 record_gen_tops_before_GC();
328
329 if (PrintGC && Verbose) {
330 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
331 gen->level(),
332 gen->stat_record()->invocations,
333 size * HeapWordSize);
334 }
335
336 if (run_verification && VerifyBeforeGC) {
337 HandleMark hm; // Discard invalid handles created during verification
338 Universe::verify(" VerifyBeforeGC:");
339 }
340 COMPILER2_PRESENT(DerivedPointerTable::clear());
341
342 if (restore_marks_for_biased_locking) {
343 // We perform this mark word preservation work lazily
344 // because it's only at this point that we know whether we
345 // absolutely have to do it; we want to avoid doing it for
346 // scavenge-only collections where it's unnecessary
347 BiasedLocking::preserve_marks();
348 }
349
350 // Do collection work
351 {
352 // Note on ref discovery: For what appear to be historical reasons,
353 // GCH enables and disabled (by enqueing) refs discovery.
354 // In the future this should be moved into the generation's
355 // collect method so that ref discovery and enqueueing concerns
356 // are local to a generation. The collect method could return
357 // an appropriate indication in the case that notification on
358 // the ref lock was needed. This will make the treatment of
359 // weak refs more uniform (and indeed remove such concerns
360 // from GCH). XXX
361
362 HandleMark hm; // Discard invalid handles created during gc
363 save_marks(); // save marks for all gens
364 // We want to discover references, but not process them yet.
365 // This mode is disabled in process_discovered_references if the
366 // generation does some collection work, or in
367 // enqueue_discovered_references if the generation returns
368 // without doing any work.
369 ReferenceProcessor* rp = gen->ref_processor();
370 // If the discovery of ("weak") refs in this generation is
371 // atomic wrt other collectors in this configuration, we
372 // are guaranteed to have empty discovered ref lists.
373 if (rp->discovery_is_atomic()) {
374 rp->enable_discovery();
375 rp->setup_policy(clear_soft_refs);
376 } else {
377 // collect() below will enable discovery as appropriate
378 }
379 gen->collect(full, clear_soft_refs, size, is_tlab);
380 if (!rp->enqueuing_is_done()) {
381 rp->enqueue_discovered_references();
382 } else {
383 rp->set_enqueuing_is_done(false);
384 }
385 rp->verify_no_references_recorded();
386 }
387
388 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
389
390 gen->stat_record()->accumulated_time.stop();
391
392 update_gc_stats(gen->level(), full);
393
394 if (run_verification && VerifyAfterGC) {
395 HandleMark hm; // Discard invalid handles created during verification
396 Universe::verify(" VerifyAfterGC:");
397 }
398
399 if (PrintGCDetails) {
400 gclog_or_tty->print(":");
401 gen->print_heap_change(prev_used);
402 }
403 }
404
405 void GenCollectedHeap::do_collection(bool full,
406 bool clear_all_soft_refs,
407 size_t size,
408 bool is_tlab,
409 int max_level) {
410 ResourceMark rm;
411 DEBUG_ONLY(Thread* my_thread = Thread::current();)
412
413 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
414 assert(my_thread->is_VM_thread() ||
415 my_thread->is_ConcurrentGC_thread(),
416 "incorrect thread type capability");
417 assert(Heap_lock->is_locked(),
418 "the requesting thread should have the Heap_lock");
419 guarantee(!is_gc_active(), "collection is not reentrant");
420 assert(max_level < n_gens(), "sanity check");
421
422 if (GC_locker::check_active_before_gc()) {
423 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
424 }
425
426 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
427 collector_policy()->should_clear_all_soft_refs();
428
429 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
430
431 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
432
433 print_heap_before_gc();
434
435 {
436 FlagSetting fl(_is_gc_active, true);
437
438 bool complete = full && (max_level == (n_gens()-1));
439 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
440 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
441 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
442 // so we can assume here that the next GC id is what we want.
443 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
444
445 gc_prologue(complete);
446 increment_total_collections(complete);
447
448 size_t gch_prev_used = used();
449 bool run_verification = total_collections() >= VerifyGCStartAt;
450
451 bool prepared_for_verification = false;
452 int max_level_collected = 0;
453 bool old_collects_young = (max_level == 1) &&
454 full &&
455 _old_gen->full_collects_younger_generations();
456 if (!old_collects_young &&
457 _young_gen->should_collect(full, size, is_tlab)) {
458 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
459 prepare_for_verify();
460 prepared_for_verification = true;
461 }
462
463 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
464 collect_generation(_young_gen,
465 full,
466 size,
467 is_tlab,
468 run_verification && VerifyGCLevel <= 0,
469 do_clear_all_soft_refs,
470 false);
471
472 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
473 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
474 // Allocation request was met by young GC.
475 size = 0;
476 }
477 }
478
479 bool must_restore_marks_for_biased_locking = false;
480
481 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
482 if (!complete) {
483 // The full_collections increment was missed above.
484 increment_total_full_collections();
485 }
486
487 pre_full_gc_dump(NULL); // do any pre full gc dumps
488
489 if (!prepared_for_verification && run_verification &&
490 VerifyGCLevel <= 1 && VerifyBeforeGC) {
491 prepare_for_verify();
492 }
493
494 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
495 collect_generation(_old_gen,
496 full,
497 size,
498 is_tlab,
499 run_verification && VerifyGCLevel <= 1,
500 do_clear_all_soft_refs,
501 true);
502
503 must_restore_marks_for_biased_locking = true;
504 max_level_collected = 1;
505 }
506
507 // Update "complete" boolean wrt what actually transpired --
508 // for instance, a promotion failure could have led to
509 // a whole heap collection.
510 complete = complete || (max_level_collected == n_gens() - 1);
511
512 if (complete) { // We did a "major" collection
513 // FIXME: See comment at pre_full_gc_dump call
514 post_full_gc_dump(NULL); // do any post full gc dumps
515 }
516
517 if (PrintGCDetails) {
518 print_heap_change(gch_prev_used);
519
520 // Print metaspace info for full GC with PrintGCDetails flag.
521 if (complete) {
522 MetaspaceAux::print_metaspace_change(metadata_prev_used);
523 }
524 }
525
526 // Adjust generation sizes.
527 if (max_level_collected == 1) {
528 _old_gen->compute_new_size();
529 }
530 _young_gen->compute_new_size();
531
532 if (complete) {
533 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
534 ClassLoaderDataGraph::purge();
535 MetaspaceAux::verify_metrics();
536 // Resize the metaspace capacity after full collections
537 MetaspaceGC::compute_new_size();
538 update_full_collections_completed();
539 }
540
541 // Track memory usage and detect low memory after GC finishes
542 MemoryService::track_memory_usage();
543
544 gc_epilogue(complete);
545
546 if (must_restore_marks_for_biased_locking) {
547 BiasedLocking::restore_marks();
548 }
549 }
550
551 print_heap_after_gc();
552
553 #ifdef TRACESPINNING
554 ParallelTaskTerminator::print_termination_counts();
555 #endif
556 }
557
558 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
559 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
560 }
561
562 void GenCollectedHeap::set_par_threads(uint t) {
563 SharedHeap::set_par_threads(t);
564 set_n_termination(t);
565 }
566
567 void GenCollectedHeap::set_n_termination(uint t) {
568 _process_strong_tasks->set_n_threads(t);
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(bool activate_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 StrongRootsScope srs(this, activate_scope);
590
591 // General roots.
592 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
593 assert(code_roots != NULL, "code root closure should always be set");
594 // _n_termination for _process_strong_tasks should be set up stream
595 // in a method not running in a GC worker. Otherwise the GC worker
596 // could be trying to change the termination condition while the task
597 // is executing in another GC worker.
598
599 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
600 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
601 }
602
603 // Some CLDs contained in the thread frames should be considered strong.
604 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
605 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
606 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
607 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
608
609 Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p);
610
611 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
612 Universe::oops_do(strong_roots);
613 }
614 // Global (strong) JNI handles
615 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
616 JNIHandles::oops_do(strong_roots);
617 }
618
619 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
620 ObjectSynchronizer::oops_do(strong_roots);
621 }
622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
623 FlatProfiler::oops_do(strong_roots);
624 }
625 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
626 Management::oops_do(strong_roots);
627 }
628 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
629 JvmtiExport::oops_do(strong_roots);
630 }
631
632 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
633 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
634 }
635
636 // All threads execute the following. A specific chunk of buckets
637 // from the StringTable are the individual tasks.
638 if (weak_roots != NULL) {
639 if (CollectedHeap::use_parallel_gc_threads()) {
640 StringTable::possibly_parallel_oops_do(weak_roots);
641 } else {
642 StringTable::oops_do(weak_roots);
643 }
644 }
645
646 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
647 if (so & SO_ScavengeCodeCache) {
648 assert(code_roots != NULL, "must supply closure for code cache");
649
650 // We only visit parts of the CodeCache when scavenging.
651 CodeCache::scavenge_root_nmethods_do(code_roots);
652 }
653 if (so & SO_AllCodeCache) {
654 assert(code_roots != NULL, "must supply closure for code cache");
655
656 // CMSCollector uses this to do intermediate-strength collections.
657 // We scan the entire code cache, since CodeCache::do_unloading is not called.
658 CodeCache::blobs_do(code_roots);
659 }
660 // Verify that the code cache contents are not subject to
661 // movement by a scavenging collection.
662 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
663 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
664 }
665
666 }
667
668 void GenCollectedHeap::gen_process_roots(int level,
669 bool younger_gens_as_roots,
670 bool activate_scope,
671 ScanningOption so,
672 bool only_strong_roots,
673 OopsInGenClosure* not_older_gens,
674 OopsInGenClosure* older_gens,
675 CLDClosure* cld_closure) {
676 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
677
678 bool is_moving_collection = false;
679 if (level == 0 || is_adjust_phase) {
680 // young collections are always moving
681 is_moving_collection = true;
682 }
683
684 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
685 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
686 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
687
688 process_roots(activate_scope, so,
689 not_older_gens, weak_roots,
690 cld_closure, weak_cld_closure,
691 &mark_code_closure);
692
693 if (younger_gens_as_roots) {
694 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
695 if (level == 1) {
696 not_older_gens->set_generation(_young_gen);
697 _young_gen->oop_iterate(not_older_gens);
698 }
699 not_older_gens->reset_generation();
700 }
701 }
702 // When collection is parallel, all threads get to cooperate to do
703 // older-gen scanning.
704 if (level == 0) {
705 older_gens->set_generation(_old_gen);
706 rem_set()->younger_refs_iterate(_old_gen, older_gens);
707 older_gens->reset_generation();
708 }
709
710 _process_strong_tasks->all_tasks_completed();
711 }
712
713
714 class AlwaysTrueClosure: public BoolObjectClosure {
715 public:
716 bool do_object_b(oop p) { return true; }
717 };
718 static AlwaysTrueClosure always_true;
719
720 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
721 JNIHandles::weak_oops_do(&always_true, root_closure);
722 _young_gen->ref_processor()->weak_oops_do(root_closure);
723 _old_gen->ref_processor()->weak_oops_do(root_closure);
724 }
725
726 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
727 void GenCollectedHeap:: \
728 oop_since_save_marks_iterate(int level, \
729 OopClosureType* cur, \
730 OopClosureType* older) { \
731 if (level == 0) { \
732 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
733 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
734 } else { \
735 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
736 } \
737 }
738
739 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
740
741 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
742
743 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
744 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
745 return false;
746 }
747 return _old_gen->no_allocs_since_save_marks();
748 }
749
750 bool GenCollectedHeap::supports_inline_contig_alloc() const {
751 return _young_gen->supports_inline_contig_alloc();
752 }
753
754 HeapWord** GenCollectedHeap::top_addr() const {
755 return _young_gen->top_addr();
756 }
757
758 HeapWord** GenCollectedHeap::end_addr() const {
759 return _young_gen->end_addr();
760 }
761
762 // public collection interfaces
763
764 void GenCollectedHeap::collect(GCCause::Cause cause) {
765 if (should_do_concurrent_full_gc(cause)) {
766 #if INCLUDE_ALL_GCS
767 // mostly concurrent full collection
768 collect_mostly_concurrent(cause);
769 #else // INCLUDE_ALL_GCS
770 ShouldNotReachHere();
771 #endif // INCLUDE_ALL_GCS
772 } else if (cause == GCCause::_wb_young_gc) {
773 // minor collection for WhiteBox API
774 collect(cause, 0);
775 } else {
776 #ifdef ASSERT
777 if (cause == GCCause::_scavenge_alot) {
778 // minor collection only
779 collect(cause, 0);
780 } else {
781 // Stop-the-world full collection
782 collect(cause, n_gens() - 1);
783 }
784 #else
785 // Stop-the-world full collection
786 collect(cause, n_gens() - 1);
787 #endif
788 }
789 }
790
791 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
792 // The caller doesn't have the Heap_lock
793 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
794 MutexLocker ml(Heap_lock);
795 collect_locked(cause, max_level);
796 }
797
798 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
799 // The caller has the Heap_lock
800 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
801 collect_locked(cause, n_gens() - 1);
802 }
803
804 // this is the private collection interface
805 // The Heap_lock is expected to be held on entry.
806
807 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
808 // Read the GC count while holding the Heap_lock
809 unsigned int gc_count_before = total_collections();
810 unsigned int full_gc_count_before = total_full_collections();
811 {
812 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
813 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
814 cause, max_level);
815 VMThread::execute(&op);
816 }
817 }
818
819 #if INCLUDE_ALL_GCS
820 bool GenCollectedHeap::create_cms_collector() {
821
822 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
823 "Unexpected generation kinds");
824 // Skip two header words in the block content verification
825 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
826 CMSCollector* collector = new CMSCollector(
827 (ConcurrentMarkSweepGeneration*)_old_gen,
828 _rem_set->as_CardTableRS(),
829 (ConcurrentMarkSweepPolicy*) collector_policy());
830
831 if (collector == NULL || !collector->completed_initialization()) {
832 if (collector) {
833 delete collector; // Be nice in embedded situation
834 }
835 vm_shutdown_during_initialization("Could not create CMS collector");
836 return false;
837 }
838 return true; // success
839 }
840
841 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
842 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
843
844 MutexLocker ml(Heap_lock);
845 // Read the GC counts while holding the Heap_lock
846 unsigned int full_gc_count_before = total_full_collections();
847 unsigned int gc_count_before = total_collections();
848 {
849 MutexUnlocker mu(Heap_lock);
850 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
851 VMThread::execute(&op);
852 }
853 }
854 #endif // INCLUDE_ALL_GCS
855
856 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
857 do_full_collection(clear_all_soft_refs, _n_gens - 1);
858 }
859
860 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
861 int max_level) {
862 int local_max_level;
863 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
864 gc_cause() == GCCause::_gc_locker) {
865 local_max_level = 0;
866 } else {
867 local_max_level = max_level;
868 }
869
870 do_collection(true /* full */,
871 clear_all_soft_refs /* clear_all_soft_refs */,
872 0 /* size */,
873 false /* is_tlab */,
874 local_max_level /* max_level */);
875 // Hack XXX FIX ME !!!
876 // A scavenge may not have been attempted, or may have
877 // been attempted and failed, because the old gen was too full
878 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
879 incremental_collection_will_fail(false /* don't consult_young */)) {
880 if (PrintGCDetails) {
881 gclog_or_tty->print_cr("GC locker: Trying a full collection "
882 "because scavenge failed");
883 }
884 // This time allow the old gen to be collected as well
885 do_collection(true /* full */,
886 clear_all_soft_refs /* clear_all_soft_refs */,
887 0 /* size */,
888 false /* is_tlab */,
889 n_gens() - 1 /* max_level */);
890 }
891 }
892
893 bool GenCollectedHeap::is_in_young(oop p) {
894 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
895 assert(result == _young_gen->is_in_reserved(p),
896 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
897 return result;
898 }
899
900 // Returns "TRUE" iff "p" points into the committed areas of the heap.
901 bool GenCollectedHeap::is_in(const void* p) const {
902 #ifndef ASSERT
903 guarantee(VerifyBeforeGC ||
904 VerifyDuringGC ||
905 VerifyBeforeExit ||
906 VerifyDuringStartup ||
907 PrintAssembly ||
908 tty->count() != 0 || // already printing
909 VerifyAfterGC ||
910 VMError::fatal_error_in_progress(), "too expensive");
911
912 #endif
913 return _young_gen->is_in(p) || _old_gen->is_in(p);
914 }
915
916 #ifdef ASSERT
917 // Don't implement this by using is_in_young(). This method is used
918 // in some cases to check that is_in_young() is correct.
919 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
920 assert(is_in_reserved(p) || p == NULL,
921 "Does not work if address is non-null and outside of the heap");
922 return p < _young_gen->reserved().end() && p != NULL;
923 }
924 #endif
925
926 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
927 _young_gen->oop_iterate(cl);
928 _old_gen->oop_iterate(cl);
929 }
930
931 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
932 _young_gen->object_iterate(cl);
933 _old_gen->object_iterate(cl);
934 }
935
936 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
937 _young_gen->safe_object_iterate(cl);
938 _old_gen->safe_object_iterate(cl);
939 }
940
941 Space* GenCollectedHeap::space_containing(const void* addr) const {
942 Space* res = _young_gen->space_containing(addr);
943 if (res != NULL) {
944 return res;
945 }
946 res = _old_gen->space_containing(addr);
947 assert(res != NULL, "Could not find containing space");
948 return res;
949 }
950
951 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
952 assert(is_in_reserved(addr), "block_start of address outside of heap");
953 if (_young_gen->is_in_reserved(addr)) {
954 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
955 return _young_gen->block_start(addr);
956 }
957
958 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
959 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
960 return _old_gen->block_start(addr);
961 }
962
963 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
964 assert(is_in_reserved(addr), "block_size of address outside of heap");
965 if (_young_gen->is_in_reserved(addr)) {
966 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
967 return _young_gen->block_size(addr);
968 }
969
970 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
971 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
972 return _old_gen->block_size(addr);
973 }
974
975 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
976 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
977 assert(block_start(addr) == addr, "addr must be a block start");
978 if (_young_gen->is_in_reserved(addr)) {
979 return _young_gen->block_is_obj(addr);
980 }
981
982 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
983 return _old_gen->block_is_obj(addr);
984 }
985
986 bool GenCollectedHeap::supports_tlab_allocation() const {
987 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
988 return _young_gen->supports_tlab_allocation();
989 }
990
991 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
992 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
993 if (_young_gen->supports_tlab_allocation()) {
994 return _young_gen->tlab_capacity();
995 }
996 return 0;
997 }
998
999 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1000 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1001 if (_young_gen->supports_tlab_allocation()) {
1002 return _young_gen->tlab_used();
1003 }
1004 return 0;
1005 }
1006
1007 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1008 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1009 if (_young_gen->supports_tlab_allocation()) {
1010 return _young_gen->unsafe_max_tlab_alloc();
1011 }
1012 return 0;
1013 }
1014
1015 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1016 bool gc_overhead_limit_was_exceeded;
1017 return collector_policy()->mem_allocate_work(size /* size */,
1018 true /* is_tlab */,
1019 &gc_overhead_limit_was_exceeded);
1020 }
1021
1022 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1023 // from the list headed by "*prev_ptr".
1024 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1025 bool first = true;
1026 size_t min_size = 0; // "first" makes this conceptually infinite.
1027 ScratchBlock **smallest_ptr, *smallest;
1028 ScratchBlock *cur = *prev_ptr;
1029 while (cur) {
1030 assert(*prev_ptr == cur, "just checking");
1031 if (first || cur->num_words < min_size) {
1032 smallest_ptr = prev_ptr;
1033 smallest = cur;
1034 min_size = smallest->num_words;
1035 first = false;
1036 }
1037 prev_ptr = &cur->next;
1038 cur = cur->next;
1039 }
1040 smallest = *smallest_ptr;
1041 *smallest_ptr = smallest->next;
1042 return smallest;
1043 }
1044
1045 // Sort the scratch block list headed by res into decreasing size order,
1046 // and set "res" to the result.
1047 static void sort_scratch_list(ScratchBlock*& list) {
1048 ScratchBlock* sorted = NULL;
1049 ScratchBlock* unsorted = list;
1050 while (unsorted) {
1051 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1052 smallest->next = sorted;
1053 sorted = smallest;
1054 }
1055 list = sorted;
1056 }
1057
1058 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1059 size_t max_alloc_words) {
1060 ScratchBlock* res = NULL;
1061 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1062 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1063 sort_scratch_list(res);
1064 return res;
1065 }
1066
1067 void GenCollectedHeap::release_scratch() {
1068 _young_gen->reset_scratch();
1069 _old_gen->reset_scratch();
1070 }
1071
1072 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1073 void do_generation(Generation* gen) {
1074 gen->prepare_for_verify();
1075 }
1076 };
1077
1078 void GenCollectedHeap::prepare_for_verify() {
1079 ensure_parsability(false); // no need to retire TLABs
1080 GenPrepareForVerifyClosure blk;
1081 generation_iterate(&blk, false);
1082 }
1083
1084 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1085 bool old_to_young) {
1086 if (old_to_young) {
1087 cl->do_generation(_old_gen);
1088 cl->do_generation(_young_gen);
1089 } else {
1090 cl->do_generation(_young_gen);
1091 cl->do_generation(_old_gen);
1092 }
1093 }
1094
1095 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1096 _young_gen->space_iterate(cl, true);
1097 _old_gen->space_iterate(cl, true);
1098 }
1099
1100 bool GenCollectedHeap::is_maximal_no_gc() const {
1101 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1102 }
1103
1104 void GenCollectedHeap::save_marks() {
1105 _young_gen->save_marks();
1106 _old_gen->save_marks();
1107 }
1108
1109 GenCollectedHeap* GenCollectedHeap::heap() {
1110 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1111 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1112 return _gch;
1113 }
1114
1115
1116 void GenCollectedHeap::prepare_for_compaction() {
1117 guarantee(_n_gens = 2, "Wrong number of generations");
1118 // Start by compacting into same gen.
1119 CompactPoint cp(_old_gen);
1120 _old_gen->prepare_for_compaction(&cp);
1121 _young_gen->prepare_for_compaction(&cp);
1122 }
1123
1124 GCStats* GenCollectedHeap::gc_stats(int level) const {
1125 if (level == 0) {
1126 return _young_gen->gc_stats();
1127 } else {
1128 return _old_gen->gc_stats();
1129 }
1130 }
1131
1132 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1133 if (!silent) {
1134 gclog_or_tty->print("%s", _old_gen->name());
1135 gclog_or_tty->print(" ");
1136 }
1137 _old_gen->verify();
1138
1139 if (!silent) {
1140 gclog_or_tty->print("%s", _young_gen->name());
1141 gclog_or_tty->print(" ");
1142 }
1143 _young_gen->verify();
1144
1145 if (!silent) {
1146 gclog_or_tty->print("remset ");
1147 }
1148 rem_set()->verify();
1149 }
1150
1151 void GenCollectedHeap::print_on(outputStream* st) const {
1152 _young_gen->print_on(st);
1153 _old_gen->print_on(st);
1154 MetaspaceAux::print_on(st);
1155 }
1156
1157 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1158 if (workers() != NULL) {
1159 workers()->threads_do(tc);
1160 }
1161 #if INCLUDE_ALL_GCS
1162 if (UseConcMarkSweepGC) {
1163 ConcurrentMarkSweepThread::threads_do(tc);
1164 }
1165 #endif // INCLUDE_ALL_GCS
1166 }
1167
1168 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1169 #if INCLUDE_ALL_GCS
1170 if (UseConcMarkSweepGC) {
1171 workers()->print_worker_threads_on(st);
1172 ConcurrentMarkSweepThread::print_all_on(st);
1173 }
1174 #endif // INCLUDE_ALL_GCS
1175 }
1176
1177 void GenCollectedHeap::print_on_error(outputStream* st) const {
1178 this->CollectedHeap::print_on_error(st);
1179
1180 #if INCLUDE_ALL_GCS
1181 if (UseConcMarkSweepGC) {
1182 st->cr();
1183 CMSCollector::print_on_error(st);
1184 }
1185 #endif // INCLUDE_ALL_GCS
1186 }
1187
1188 void GenCollectedHeap::print_tracing_info() const {
1189 if (TraceYoungGenTime) {
1190 _young_gen->print_summary_info();
1191 }
1192 if (TraceOldGenTime) {
1193 _old_gen->print_summary_info();
1194 }
1195 }
1196
1197 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1198 if (PrintGCDetails && Verbose) {
1199 gclog_or_tty->print(" " SIZE_FORMAT
1200 "->" SIZE_FORMAT
1201 "(" SIZE_FORMAT ")",
1202 prev_used, used(), capacity());
1203 } else {
1204 gclog_or_tty->print(" " SIZE_FORMAT "K"
1205 "->" SIZE_FORMAT "K"
1206 "(" SIZE_FORMAT "K)",
1207 prev_used / K, used() / K, capacity() / K);
1208 }
1209 }
1210
1211 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1212 private:
1213 bool _full;
1214 public:
1215 void do_generation(Generation* gen) {
1216 gen->gc_prologue(_full);
1217 }
1218 GenGCPrologueClosure(bool full) : _full(full) {};
1219 };
1220
1221 void GenCollectedHeap::gc_prologue(bool full) {
1222 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1223
1224 always_do_update_barrier = false;
1225 // Fill TLAB's and such
1226 CollectedHeap::accumulate_statistics_all_tlabs();
1227 ensure_parsability(true); // retire TLABs
1228
1229 // Walk generations
1230 GenGCPrologueClosure blk(full);
1231 generation_iterate(&blk, false); // not old-to-young.
1232 };
1233
1234 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1235 private:
1236 bool _full;
1237 public:
1238 void do_generation(Generation* gen) {
1239 gen->gc_epilogue(_full);
1240 }
1241 GenGCEpilogueClosure(bool full) : _full(full) {};
1242 };
1243
1244 void GenCollectedHeap::gc_epilogue(bool full) {
1245 #ifdef COMPILER2
1246 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1247 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1248 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1249 #endif /* COMPILER2 */
1250
1251 resize_all_tlabs();
1252
1253 GenGCEpilogueClosure blk(full);
1254 generation_iterate(&blk, false); // not old-to-young.
1255
1256 if (!CleanChunkPoolAsync) {
1257 Chunk::clean_chunk_pool();
1258 }
1259
1260 MetaspaceCounters::update_performance_counters();
1261 CompressedClassSpaceCounters::update_performance_counters();
1262
1263 always_do_update_barrier = UseConcMarkSweepGC;
1264 };
1265
1266 #ifndef PRODUCT
1267 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1268 private:
1269 public:
1270 void do_generation(Generation* gen) {
1271 gen->record_spaces_top();
1272 }
1273 };
1274
1275 void GenCollectedHeap::record_gen_tops_before_GC() {
1276 if (ZapUnusedHeapArea) {
1277 GenGCSaveTopsBeforeGCClosure blk;
1278 generation_iterate(&blk, false); // not old-to-young.
1279 }
1280 }
1281 #endif // not PRODUCT
1282
1283 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1284 public:
1285 void do_generation(Generation* gen) {
1286 gen->ensure_parsability();
1287 }
1288 };
1289
1290 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1291 CollectedHeap::ensure_parsability(retire_tlabs);
1292 GenEnsureParsabilityClosure ep_cl;
1293 generation_iterate(&ep_cl, false);
1294 }
1295
1296 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1297 oop obj,
1298 size_t obj_size) {
1299 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1300 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1301 HeapWord* result = NULL;
1302
1303 result = old_gen->expand_and_allocate(obj_size, false);
1304
1305 if (result != NULL) {
1306 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1307 }
1308 return oop(result);
1309 }
1310
1311 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1312 jlong _time; // in ms
1313 jlong _now; // in ms
1314
1315 public:
1316 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1317
1318 jlong time() { return _time; }
1319
1320 void do_generation(Generation* gen) {
1321 _time = MIN2(_time, gen->time_of_last_gc(_now));
1322 }
1323 };
1324
1325 jlong GenCollectedHeap::millis_since_last_gc() {
1326 // We need a monotonically non-decreasing time in ms but
1327 // os::javaTimeMillis() does not guarantee monotonicity.
1328 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1329 GenTimeOfLastGCClosure tolgc_cl(now);
1330 // iterate over generations getting the oldest
1331 // time that a generation was collected
1332 generation_iterate(&tolgc_cl, false);
1333
1334 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1335 // provided the underlying platform provides such a time source
1336 // (and it is bug free). So we still have to guard against getting
1337 // back a time later than 'now'.
1338 jlong retVal = now - tolgc_cl.time();
1339 if (retVal < 0) {
1340 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1341 return 0;
1342 }
1343 return retVal;
1344 }