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 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 _workers = NULL;
95 }
96 }
97
98 jint GenCollectedHeap::initialize() {
99 CollectedHeap::pre_initialize();
100
101 _n_gens = gen_policy()->number_of_generations();
102 assert(_n_gens == 2, "There is no support for more than two generations");
103
104 // While there are no constraints in the GC code that HeapWordSize
105 // be any particular value, there are multiple other areas in the
106 // system which believe this to be true (e.g. oop->object_size in some
107 // cases incorrectly returns the size in wordSize units rather than
108 // HeapWordSize).
109 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
110
111 // Allocate space for the heap.
112
113 char* heap_address;
114 ReservedSpace heap_rs;
115
116 size_t heap_alignment = collector_policy()->heap_alignment();
117
118 heap_address = allocate(heap_alignment, &heap_rs);
119
120 if (!heap_rs.is_reserved()) {
121 vm_shutdown_during_initialization(
122 "Could not reserve enough space for object heap");
123 return JNI_ENOMEM;
124 }
125
126 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
127
128 _rem_set = collector_policy()->create_rem_set(reserved_region());
129 _barrier_set = rem_set()->bs();
130 oopDesc::set_bs(_barrier_set);
131
132 _gch = this;
133
134 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
135 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set());
136 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
137
138 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
139 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set());
140 clear_incremental_collection_failed();
141
142 #if INCLUDE_ALL_GCS
143 // If we are running CMS, create the collector responsible
144 // for collecting the CMS generations.
145 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
146 bool success = create_cms_collector();
147 if (!success) return JNI_ENOMEM;
148 }
149 #endif // INCLUDE_ALL_GCS
150
151 return JNI_OK;
152 }
153
154 char* GenCollectedHeap::allocate(size_t alignment,
155 ReservedSpace* heap_rs){
156 // Now figure out the total size.
157 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
158 assert(alignment % pageSize == 0, "Must be");
159
160 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
161 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
162
163 // Check for overflow.
164 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
165 if (total_reserved < young_spec->max_size()) {
166 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
167 "the maximum representable size");
168 }
169 assert(total_reserved % alignment == 0,
170 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
171 SIZE_FORMAT, total_reserved, alignment));
172
173 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
174 return heap_rs->base();
175 }
176
177 void GenCollectedHeap::post_initialize() {
178 CollectedHeap::post_initialize();
179 ref_processing_init();
180 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
181 guarantee(policy->is_generation_policy(), "Illegal policy type");
182 assert((_young_gen->kind() == Generation::DefNew) ||
183 (_young_gen->kind() == Generation::ParNew),
184 "Wrong youngest generation type");
185 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
186
187 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
188 _old_gen->kind() == Generation::MarkSweepCompact,
189 "Wrong generation kind");
190
191 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
192 _old_gen->capacity(),
193 def_new_gen->from()->capacity());
194 policy->initialize_gc_policy_counters();
195 }
196
197 void GenCollectedHeap::ref_processing_init() {
198 _young_gen->ref_processor_init();
199 _old_gen->ref_processor_init();
200 }
201
202 size_t GenCollectedHeap::capacity() const {
203 return _young_gen->capacity() + _old_gen->capacity();
204 }
205
206 size_t GenCollectedHeap::used() const {
207 return _young_gen->used() + _old_gen->used();
208 }
209
210 // Save the "used_region" for generations level and lower.
211 void GenCollectedHeap::save_used_regions(int level) {
212 assert(level >= 0, "Illegal level parameter");
213 assert(level < _n_gens, "Illegal level parameter");
214 if (level == 1) {
215 _old_gen->save_used_region();
216 }
217 _young_gen->save_used_region();
218 }
219
220 size_t GenCollectedHeap::max_capacity() const {
221 return _young_gen->max_capacity() + _old_gen->max_capacity();
222 }
223
224 // Update the _full_collections_completed counter
225 // at the end of a stop-world full GC.
226 unsigned int GenCollectedHeap::update_full_collections_completed() {
227 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
228 assert(_full_collections_completed <= _total_full_collections,
229 "Can't complete more collections than were started");
230 _full_collections_completed = _total_full_collections;
231 ml.notify_all();
232 return _full_collections_completed;
233 }
234
235 // Update the _full_collections_completed counter, as appropriate,
236 // at the end of a concurrent GC cycle. Note the conditional update
237 // below to allow this method to be called by a concurrent collector
238 // without synchronizing in any manner with the VM thread (which
239 // may already have initiated a STW full collection "concurrently").
240 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
241 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
242 assert((_full_collections_completed <= _total_full_collections) &&
243 (count <= _total_full_collections),
244 "Can't complete more collections than were started");
245 if (count > _full_collections_completed) {
246 _full_collections_completed = count;
247 ml.notify_all();
248 }
249 return _full_collections_completed;
250 }
251
252
253 #ifndef PRODUCT
254 // Override of memory state checking method in CollectedHeap:
255 // Some collectors (CMS for example) can't have badHeapWordVal written
256 // in the first two words of an object. (For instance , in the case of
257 // CMS these words hold state used to synchronize between certain
258 // (concurrent) GC steps and direct allocating mutators.)
259 // The skip_header_HeapWords() method below, allows us to skip
260 // over the requisite number of HeapWord's. Note that (for
261 // generational collectors) this means that those many words are
262 // skipped in each object, irrespective of the generation in which
263 // that object lives. The resultant loss of precision seems to be
264 // harmless and the pain of avoiding that imprecision appears somewhat
265 // higher than we are prepared to pay for such rudimentary debugging
266 // support.
267 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
268 size_t size) {
269 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
270 // We are asked to check a size in HeapWords,
271 // but the memory is mangled in juint words.
272 juint* start = (juint*) (addr + skip_header_HeapWords());
273 juint* end = (juint*) (addr + size);
274 for (juint* slot = start; slot < end; slot += 1) {
275 assert(*slot == badHeapWordVal,
276 "Found non badHeapWordValue in pre-allocation check");
277 }
278 }
279 }
280 #endif
281
282 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
283 bool is_tlab,
284 bool first_only) {
285 HeapWord* res = NULL;
286
287 if (_young_gen->should_allocate(size, is_tlab)) {
288 res = _young_gen->allocate(size, is_tlab);
289 if (res != NULL || first_only) {
290 return res;
291 }
292 }
293
294 if (_old_gen->should_allocate(size, is_tlab)) {
295 res = _old_gen->allocate(size, is_tlab);
296 }
297
298 return res;
299 }
300
301 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
302 bool* gc_overhead_limit_was_exceeded) {
303 return collector_policy()->mem_allocate_work(size,
304 false /* is_tlab */,
305 gc_overhead_limit_was_exceeded);
306 }
307
308 bool GenCollectedHeap::must_clear_all_soft_refs() {
309 return _gc_cause == GCCause::_last_ditch_collection;
310 }
311
312 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
313 return UseConcMarkSweepGC &&
314 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
315 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
316 }
317
318 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
319 bool is_tlab, bool run_verification, bool clear_soft_refs,
320 bool restore_marks_for_biased_locking) {
321 // Timer for individual generations. Last argument is false: no CR
322 // FIXME: We should try to start the timing earlier to cover more of the GC pause
323 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
324 // so we can assume here that the next GC id is what we want.
325 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
326 TraceCollectorStats tcs(gen->counters());
327 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
328
329 size_t prev_used = gen->used();
330 gen->stat_record()->invocations++;
331 gen->stat_record()->accumulated_time.start();
332
333 // Must be done anew before each collection because
334 // a previous collection will do mangling and will
335 // change top of some spaces.
336 record_gen_tops_before_GC();
337
338 if (PrintGC && Verbose) {
339 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
340 gen->level(),
341 gen->stat_record()->invocations,
342 size * HeapWordSize);
343 }
344
345 if (run_verification && VerifyBeforeGC) {
346 HandleMark hm; // Discard invalid handles created during verification
347 Universe::verify(" VerifyBeforeGC:");
348 }
349 COMPILER2_PRESENT(DerivedPointerTable::clear());
350
351 if (restore_marks_for_biased_locking) {
352 // We perform this mark word preservation work lazily
353 // because it's only at this point that we know whether we
354 // absolutely have to do it; we want to avoid doing it for
355 // scavenge-only collections where it's unnecessary
356 BiasedLocking::preserve_marks();
357 }
358
359 // Do collection work
360 {
361 // Note on ref discovery: For what appear to be historical reasons,
362 // GCH enables and disabled (by enqueing) refs discovery.
363 // In the future this should be moved into the generation's
364 // collect method so that ref discovery and enqueueing concerns
365 // are local to a generation. The collect method could return
366 // an appropriate indication in the case that notification on
367 // the ref lock was needed. This will make the treatment of
368 // weak refs more uniform (and indeed remove such concerns
369 // from GCH). XXX
370
371 HandleMark hm; // Discard invalid handles created during gc
372 save_marks(); // save marks for all gens
373 // We want to discover references, but not process them yet.
374 // This mode is disabled in process_discovered_references if the
375 // generation does some collection work, or in
376 // enqueue_discovered_references if the generation returns
377 // without doing any work.
378 ReferenceProcessor* rp = gen->ref_processor();
379 // If the discovery of ("weak") refs in this generation is
380 // atomic wrt other collectors in this configuration, we
381 // are guaranteed to have empty discovered ref lists.
382 if (rp->discovery_is_atomic()) {
383 rp->enable_discovery();
384 rp->setup_policy(clear_soft_refs);
385 } else {
386 // collect() below will enable discovery as appropriate
387 }
388 gen->collect(full, clear_soft_refs, size, is_tlab);
389 if (!rp->enqueuing_is_done()) {
390 rp->enqueue_discovered_references();
391 } else {
392 rp->set_enqueuing_is_done(false);
393 }
394 rp->verify_no_references_recorded();
395 }
396
397 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
398
399 gen->stat_record()->accumulated_time.stop();
400
401 update_gc_stats(gen->level(), full);
402
403 if (run_verification && VerifyAfterGC) {
404 HandleMark hm; // Discard invalid handles created during verification
405 Universe::verify(" VerifyAfterGC:");
406 }
407
408 if (PrintGCDetails) {
409 gclog_or_tty->print(":");
410 gen->print_heap_change(prev_used);
411 }
412 }
413
414 void GenCollectedHeap::do_collection(bool full,
415 bool clear_all_soft_refs,
416 size_t size,
417 bool is_tlab,
418 int max_level) {
419 ResourceMark rm;
420 DEBUG_ONLY(Thread* my_thread = Thread::current();)
421
422 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
423 assert(my_thread->is_VM_thread() ||
424 my_thread->is_ConcurrentGC_thread(),
425 "incorrect thread type capability");
426 assert(Heap_lock->is_locked(),
427 "the requesting thread should have the Heap_lock");
428 guarantee(!is_gc_active(), "collection is not reentrant");
429 assert(max_level < n_gens(), "sanity check");
430
431 if (GC_locker::check_active_before_gc()) {
432 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
433 }
434
435 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
436 collector_policy()->should_clear_all_soft_refs();
437
438 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
439
440 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
441
442 print_heap_before_gc();
443
444 {
445 FlagSetting fl(_is_gc_active, true);
446
447 bool complete = full && (max_level == (n_gens()-1));
448 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
449 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
450 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
451 // so we can assume here that the next GC id is what we want.
452 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
453
454 gc_prologue(complete);
455 increment_total_collections(complete);
456
457 size_t gch_prev_used = used();
458 bool run_verification = total_collections() >= VerifyGCStartAt;
459
460 bool prepared_for_verification = false;
461 int max_level_collected = 0;
462 bool old_collects_young = (max_level == 1) &&
463 full &&
464 _old_gen->full_collects_younger_generations();
465 if (!old_collects_young &&
466 _young_gen->should_collect(full, size, is_tlab)) {
467 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
468 prepare_for_verify();
469 prepared_for_verification = true;
470 }
471
472 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
473 collect_generation(_young_gen,
474 full,
475 size,
476 is_tlab,
477 run_verification && VerifyGCLevel <= 0,
478 do_clear_all_soft_refs,
479 false);
480
481 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
482 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
483 // Allocation request was met by young GC.
484 size = 0;
485 }
486 }
487
488 bool must_restore_marks_for_biased_locking = false;
489
490 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
491 if (!complete) {
492 // The full_collections increment was missed above.
493 increment_total_full_collections();
494 }
495
496 pre_full_gc_dump(NULL); // do any pre full gc dumps
497
498 if (!prepared_for_verification && run_verification &&
499 VerifyGCLevel <= 1 && VerifyBeforeGC) {
500 prepare_for_verify();
501 }
502
503 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
504 collect_generation(_old_gen,
505 full,
506 size,
507 is_tlab,
508 run_verification && VerifyGCLevel <= 1,
509 do_clear_all_soft_refs,
510 true);
511
512 must_restore_marks_for_biased_locking = true;
513 max_level_collected = 1;
514 }
515
516 // Update "complete" boolean wrt what actually transpired --
517 // for instance, a promotion failure could have led to
518 // a whole heap collection.
519 complete = complete || (max_level_collected == n_gens() - 1);
520
521 if (complete) { // We did a "major" collection
522 // FIXME: See comment at pre_full_gc_dump call
523 post_full_gc_dump(NULL); // do any post full gc dumps
524 }
525
526 if (PrintGCDetails) {
527 print_heap_change(gch_prev_used);
528
529 // Print metaspace info for full GC with PrintGCDetails flag.
530 if (complete) {
531 MetaspaceAux::print_metaspace_change(metadata_prev_used);
532 }
533 }
534
535 // Adjust generation sizes.
536 if (max_level_collected == 1) {
537 _old_gen->compute_new_size();
538 }
539 _young_gen->compute_new_size();
540
541 if (complete) {
542 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
543 ClassLoaderDataGraph::purge();
544 MetaspaceAux::verify_metrics();
545 // Resize the metaspace capacity after full collections
546 MetaspaceGC::compute_new_size();
547 update_full_collections_completed();
548 }
549
550 // Track memory usage and detect low memory after GC finishes
551 MemoryService::track_memory_usage();
552
553 gc_epilogue(complete);
554
555 if (must_restore_marks_for_biased_locking) {
556 BiasedLocking::restore_marks();
557 }
558 }
559
560 print_heap_after_gc();
561
562 #ifdef TRACESPINNING
563 ParallelTaskTerminator::print_termination_counts();
564 #endif
565 }
566
567 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
568 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
569 }
570
571 void GenCollectedHeap::set_par_threads(uint t) {
572 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
573 CollectedHeap::set_par_threads(t);
574 set_n_termination(t);
575 }
576
577 void GenCollectedHeap::set_n_termination(uint t) {
578 _process_strong_tasks->set_n_threads(t);
579 }
580
581 #ifdef ASSERT
582 class AssertNonScavengableClosure: public OopClosure {
583 public:
584 virtual void do_oop(oop* p) {
585 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
586 "Referent should not be scavengable."); }
587 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
588 };
589 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
590 #endif
591
592 void GenCollectedHeap::process_roots(bool activate_scope,
593 ScanningOption so,
594 OopClosure* strong_roots,
595 OopClosure* weak_roots,
596 CLDClosure* strong_cld_closure,
597 CLDClosure* weak_cld_closure,
598 CodeBlobClosure* code_roots) {
599 StrongRootsScope srs(this, activate_scope);
600
601 // General roots.
602 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
603 assert(code_roots != NULL, "code root closure should always be set");
604 // _n_termination for _process_strong_tasks should be set up stream
605 // in a method not running in a GC worker. Otherwise the GC worker
606 // could be trying to change the termination condition while the task
607 // is executing in another GC worker.
608
609 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
610 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
611 }
612
613 // Some CLDs contained in the thread frames should be considered strong.
614 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
615 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
616 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
617 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
618
619 bool is_par =n_par_threads() > 0;
620 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
621
622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
623 Universe::oops_do(strong_roots);
624 }
625 // Global (strong) JNI handles
626 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
627 JNIHandles::oops_do(strong_roots);
628 }
629
630 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
631 ObjectSynchronizer::oops_do(strong_roots);
632 }
633 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
634 FlatProfiler::oops_do(strong_roots);
635 }
636 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
637 Management::oops_do(strong_roots);
638 }
639 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
640 JvmtiExport::oops_do(strong_roots);
641 }
642
643 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
644 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
645 }
646
647 // All threads execute the following. A specific chunk of buckets
648 // from the StringTable are the individual tasks.
649 if (weak_roots != NULL) {
650 if (CollectedHeap::use_parallel_gc_threads()) {
651 StringTable::possibly_parallel_oops_do(weak_roots);
652 } else {
653 StringTable::oops_do(weak_roots);
654 }
655 }
656
657 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
658 if (so & SO_ScavengeCodeCache) {
659 assert(code_roots != NULL, "must supply closure for code cache");
660
661 // We only visit parts of the CodeCache when scavenging.
662 CodeCache::scavenge_root_nmethods_do(code_roots);
663 }
664 if (so & SO_AllCodeCache) {
665 assert(code_roots != NULL, "must supply closure for code cache");
666
667 // CMSCollector uses this to do intermediate-strength collections.
668 // We scan the entire code cache, since CodeCache::do_unloading is not called.
669 CodeCache::blobs_do(code_roots);
670 }
671 // Verify that the code cache contents are not subject to
672 // movement by a scavenging collection.
673 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
674 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
675 }
676
677 }
678
679 void GenCollectedHeap::gen_process_roots(int level,
680 bool younger_gens_as_roots,
681 bool activate_scope,
682 ScanningOption so,
683 bool only_strong_roots,
684 OopsInGenClosure* not_older_gens,
685 OopsInGenClosure* older_gens,
686 CLDClosure* cld_closure) {
687 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
688
689 bool is_moving_collection = false;
690 if (level == 0 || is_adjust_phase) {
691 // young collections are always moving
692 is_moving_collection = true;
693 }
694
695 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
696 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
697 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
698
699 process_roots(activate_scope, so,
700 not_older_gens, weak_roots,
701 cld_closure, weak_cld_closure,
702 &mark_code_closure);
703
704 if (younger_gens_as_roots) {
705 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
706 if (level == 1) {
707 not_older_gens->set_generation(_young_gen);
708 _young_gen->oop_iterate(not_older_gens);
709 }
710 not_older_gens->reset_generation();
711 }
712 }
713 // When collection is parallel, all threads get to cooperate to do
714 // older-gen scanning.
715 if (level == 0) {
716 older_gens->set_generation(_old_gen);
717 rem_set()->younger_refs_iterate(_old_gen, older_gens);
718 older_gens->reset_generation();
719 }
720
721 _process_strong_tasks->all_tasks_completed();
722 }
723
724
725 class AlwaysTrueClosure: public BoolObjectClosure {
726 public:
727 bool do_object_b(oop p) { return true; }
728 };
729 static AlwaysTrueClosure always_true;
730
731 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
732 JNIHandles::weak_oops_do(&always_true, root_closure);
733 _young_gen->ref_processor()->weak_oops_do(root_closure);
734 _old_gen->ref_processor()->weak_oops_do(root_closure);
735 }
736
737 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
738 void GenCollectedHeap:: \
739 oop_since_save_marks_iterate(int level, \
740 OopClosureType* cur, \
741 OopClosureType* older) { \
742 if (level == 0) { \
743 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
744 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
745 } else { \
746 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
747 } \
748 }
749
750 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
751
752 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
753
754 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
755 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
756 return false;
757 }
758 return _old_gen->no_allocs_since_save_marks();
759 }
760
761 bool GenCollectedHeap::supports_inline_contig_alloc() const {
762 return _young_gen->supports_inline_contig_alloc();
763 }
764
765 HeapWord** GenCollectedHeap::top_addr() const {
766 return _young_gen->top_addr();
767 }
768
769 HeapWord** GenCollectedHeap::end_addr() const {
770 return _young_gen->end_addr();
771 }
772
773 // public collection interfaces
774
775 void GenCollectedHeap::collect(GCCause::Cause cause) {
776 if (should_do_concurrent_full_gc(cause)) {
777 #if INCLUDE_ALL_GCS
778 // mostly concurrent full collection
779 collect_mostly_concurrent(cause);
780 #else // INCLUDE_ALL_GCS
781 ShouldNotReachHere();
782 #endif // INCLUDE_ALL_GCS
783 } else if (cause == GCCause::_wb_young_gc) {
784 // minor collection for WhiteBox API
785 collect(cause, 0);
786 } else {
787 #ifdef ASSERT
788 if (cause == GCCause::_scavenge_alot) {
789 // minor collection only
790 collect(cause, 0);
791 } else {
792 // Stop-the-world full collection
793 collect(cause, n_gens() - 1);
794 }
795 #else
796 // Stop-the-world full collection
797 collect(cause, n_gens() - 1);
798 #endif
799 }
800 }
801
802 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
803 // The caller doesn't have the Heap_lock
804 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
805 MutexLocker ml(Heap_lock);
806 collect_locked(cause, max_level);
807 }
808
809 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
810 // The caller has the Heap_lock
811 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
812 collect_locked(cause, n_gens() - 1);
813 }
814
815 // this is the private collection interface
816 // The Heap_lock is expected to be held on entry.
817
818 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
819 // Read the GC count while holding the Heap_lock
820 unsigned int gc_count_before = total_collections();
821 unsigned int full_gc_count_before = total_full_collections();
822 {
823 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
824 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
825 cause, max_level);
826 VMThread::execute(&op);
827 }
828 }
829
830 #if INCLUDE_ALL_GCS
831 bool GenCollectedHeap::create_cms_collector() {
832
833 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
834 "Unexpected generation kinds");
835 // Skip two header words in the block content verification
836 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
837 CMSCollector* collector = new CMSCollector(
838 (ConcurrentMarkSweepGeneration*)_old_gen,
839 _rem_set->as_CardTableRS(),
840 (ConcurrentMarkSweepPolicy*) collector_policy());
841
842 if (collector == NULL || !collector->completed_initialization()) {
843 if (collector) {
844 delete collector; // Be nice in embedded situation
845 }
846 vm_shutdown_during_initialization("Could not create CMS collector");
847 return false;
848 }
849 return true; // success
850 }
851
852 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
853 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
854
855 MutexLocker ml(Heap_lock);
856 // Read the GC counts while holding the Heap_lock
857 unsigned int full_gc_count_before = total_full_collections();
858 unsigned int gc_count_before = total_collections();
859 {
860 MutexUnlocker mu(Heap_lock);
861 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
862 VMThread::execute(&op);
863 }
864 }
865 #endif // INCLUDE_ALL_GCS
866
867 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
868 do_full_collection(clear_all_soft_refs, _n_gens - 1);
869 }
870
871 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
872 int max_level) {
873 int local_max_level;
874 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
875 gc_cause() == GCCause::_gc_locker) {
876 local_max_level = 0;
877 } else {
878 local_max_level = max_level;
879 }
880
881 do_collection(true /* full */,
882 clear_all_soft_refs /* clear_all_soft_refs */,
883 0 /* size */,
884 false /* is_tlab */,
885 local_max_level /* max_level */);
886 // Hack XXX FIX ME !!!
887 // A scavenge may not have been attempted, or may have
888 // been attempted and failed, because the old gen was too full
889 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
890 incremental_collection_will_fail(false /* don't consult_young */)) {
891 if (PrintGCDetails) {
892 gclog_or_tty->print_cr("GC locker: Trying a full collection "
893 "because scavenge failed");
894 }
895 // This time allow the old gen to be collected as well
896 do_collection(true /* full */,
897 clear_all_soft_refs /* clear_all_soft_refs */,
898 0 /* size */,
899 false /* is_tlab */,
900 n_gens() - 1 /* max_level */);
901 }
902 }
903
904 bool GenCollectedHeap::is_in_young(oop p) {
905 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
906 assert(result == _young_gen->is_in_reserved(p),
907 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
908 return result;
909 }
910
911 // Returns "TRUE" iff "p" points into the committed areas of the heap.
912 bool GenCollectedHeap::is_in(const void* p) const {
913 #ifndef ASSERT
914 guarantee(VerifyBeforeGC ||
915 VerifyDuringGC ||
916 VerifyBeforeExit ||
917 VerifyDuringStartup ||
918 PrintAssembly ||
919 tty->count() != 0 || // already printing
920 VerifyAfterGC ||
921 VMError::fatal_error_in_progress(), "too expensive");
922
923 #endif
924 return _young_gen->is_in(p) || _old_gen->is_in(p);
925 }
926
927 #ifdef ASSERT
928 // Don't implement this by using is_in_young(). This method is used
929 // in some cases to check that is_in_young() is correct.
930 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
931 assert(is_in_reserved(p) || p == NULL,
932 "Does not work if address is non-null and outside of the heap");
933 return p < _young_gen->reserved().end() && p != NULL;
934 }
935 #endif
936
937 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
938 _young_gen->oop_iterate(cl);
939 _old_gen->oop_iterate(cl);
940 }
941
942 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
943 _young_gen->object_iterate(cl);
944 _old_gen->object_iterate(cl);
945 }
946
947 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
948 _young_gen->safe_object_iterate(cl);
949 _old_gen->safe_object_iterate(cl);
950 }
951
952 Space* GenCollectedHeap::space_containing(const void* addr) const {
953 Space* res = _young_gen->space_containing(addr);
954 if (res != NULL) {
955 return res;
956 }
957 res = _old_gen->space_containing(addr);
958 assert(res != NULL, "Could not find containing space");
959 return res;
960 }
961
962 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
963 assert(is_in_reserved(addr), "block_start of address outside of heap");
964 if (_young_gen->is_in_reserved(addr)) {
965 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
966 return _young_gen->block_start(addr);
967 }
968
969 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
970 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
971 return _old_gen->block_start(addr);
972 }
973
974 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
975 assert(is_in_reserved(addr), "block_size of address outside of heap");
976 if (_young_gen->is_in_reserved(addr)) {
977 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
978 return _young_gen->block_size(addr);
979 }
980
981 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
982 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
983 return _old_gen->block_size(addr);
984 }
985
986 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
987 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
988 assert(block_start(addr) == addr, "addr must be a block start");
989 if (_young_gen->is_in_reserved(addr)) {
990 return _young_gen->block_is_obj(addr);
991 }
992
993 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
994 return _old_gen->block_is_obj(addr);
995 }
996
997 bool GenCollectedHeap::supports_tlab_allocation() const {
998 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
999 return _young_gen->supports_tlab_allocation();
1000 }
1001
1002 size_t GenCollectedHeap::tlab_capacity(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->tlab_capacity();
1006 }
1007 return 0;
1008 }
1009
1010 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1011 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1012 if (_young_gen->supports_tlab_allocation()) {
1013 return _young_gen->tlab_used();
1014 }
1015 return 0;
1016 }
1017
1018 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1019 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1020 if (_young_gen->supports_tlab_allocation()) {
1021 return _young_gen->unsafe_max_tlab_alloc();
1022 }
1023 return 0;
1024 }
1025
1026 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1027 bool gc_overhead_limit_was_exceeded;
1028 return collector_policy()->mem_allocate_work(size /* size */,
1029 true /* is_tlab */,
1030 &gc_overhead_limit_was_exceeded);
1031 }
1032
1033 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1034 // from the list headed by "*prev_ptr".
1035 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1036 bool first = true;
1037 size_t min_size = 0; // "first" makes this conceptually infinite.
1038 ScratchBlock **smallest_ptr, *smallest;
1039 ScratchBlock *cur = *prev_ptr;
1040 while (cur) {
1041 assert(*prev_ptr == cur, "just checking");
1042 if (first || cur->num_words < min_size) {
1043 smallest_ptr = prev_ptr;
1044 smallest = cur;
1045 min_size = smallest->num_words;
1046 first = false;
1047 }
1048 prev_ptr = &cur->next;
1049 cur = cur->next;
1050 }
1051 smallest = *smallest_ptr;
1052 *smallest_ptr = smallest->next;
1053 return smallest;
1054 }
1055
1056 // Sort the scratch block list headed by res into decreasing size order,
1057 // and set "res" to the result.
1058 static void sort_scratch_list(ScratchBlock*& list) {
1059 ScratchBlock* sorted = NULL;
1060 ScratchBlock* unsorted = list;
1061 while (unsorted) {
1062 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1063 smallest->next = sorted;
1064 sorted = smallest;
1065 }
1066 list = sorted;
1067 }
1068
1069 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1070 size_t max_alloc_words) {
1071 ScratchBlock* res = NULL;
1072 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1073 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1074 sort_scratch_list(res);
1075 return res;
1076 }
1077
1078 void GenCollectedHeap::release_scratch() {
1079 _young_gen->reset_scratch();
1080 _old_gen->reset_scratch();
1081 }
1082
1083 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1084 void do_generation(Generation* gen) {
1085 gen->prepare_for_verify();
1086 }
1087 };
1088
1089 void GenCollectedHeap::prepare_for_verify() {
1090 ensure_parsability(false); // no need to retire TLABs
1091 GenPrepareForVerifyClosure blk;
1092 generation_iterate(&blk, false);
1093 }
1094
1095 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1096 bool old_to_young) {
1097 if (old_to_young) {
1098 cl->do_generation(_old_gen);
1099 cl->do_generation(_young_gen);
1100 } else {
1101 cl->do_generation(_young_gen);
1102 cl->do_generation(_old_gen);
1103 }
1104 }
1105
1106 bool GenCollectedHeap::is_maximal_no_gc() const {
1107 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1108 }
1109
1110 void GenCollectedHeap::save_marks() {
1111 _young_gen->save_marks();
1112 _old_gen->save_marks();
1113 }
1114
1115 GenCollectedHeap* GenCollectedHeap::heap() {
1116 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1117 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1118 return _gch;
1119 }
1120
1121
1122 void GenCollectedHeap::prepare_for_compaction() {
1123 guarantee(_n_gens = 2, "Wrong number of generations");
1124 // Start by compacting into same gen.
1125 CompactPoint cp(_old_gen);
1126 _old_gen->prepare_for_compaction(&cp);
1127 _young_gen->prepare_for_compaction(&cp);
1128 }
1129
1130 GCStats* GenCollectedHeap::gc_stats(int level) const {
1131 if (level == 0) {
1132 return _young_gen->gc_stats();
1133 } else {
1134 return _old_gen->gc_stats();
1135 }
1136 }
1137
1138 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1139 if (!silent) {
1140 gclog_or_tty->print("%s", _old_gen->name());
1141 gclog_or_tty->print(" ");
1142 }
1143 _old_gen->verify();
1144
1145 if (!silent) {
1146 gclog_or_tty->print("%s", _young_gen->name());
1147 gclog_or_tty->print(" ");
1148 }
1149 _young_gen->verify();
1150
1151 if (!silent) {
1152 gclog_or_tty->print("remset ");
1153 }
1154 rem_set()->verify();
1155 }
1156
1157 void GenCollectedHeap::print_on(outputStream* st) const {
1158 _young_gen->print_on(st);
1159 _old_gen->print_on(st);
1160 MetaspaceAux::print_on(st);
1161 }
1162
1163 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1164 if (workers() != NULL) {
1165 workers()->threads_do(tc);
1166 }
1167 #if INCLUDE_ALL_GCS
1168 if (UseConcMarkSweepGC) {
1169 ConcurrentMarkSweepThread::threads_do(tc);
1170 }
1171 #endif // INCLUDE_ALL_GCS
1172 }
1173
1174 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1175 #if INCLUDE_ALL_GCS
1176 if (UseConcMarkSweepGC) {
1177 workers()->print_worker_threads_on(st);
1178 ConcurrentMarkSweepThread::print_all_on(st);
1179 }
1180 #endif // INCLUDE_ALL_GCS
1181 }
1182
1183 void GenCollectedHeap::print_on_error(outputStream* st) const {
1184 this->CollectedHeap::print_on_error(st);
1185
1186 #if INCLUDE_ALL_GCS
1187 if (UseConcMarkSweepGC) {
1188 st->cr();
1189 CMSCollector::print_on_error(st);
1190 }
1191 #endif // INCLUDE_ALL_GCS
1192 }
1193
1194 void GenCollectedHeap::print_tracing_info() const {
1195 if (TraceYoungGenTime) {
1196 _young_gen->print_summary_info();
1197 }
1198 if (TraceOldGenTime) {
1199 _old_gen->print_summary_info();
1200 }
1201 }
1202
1203 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1204 if (PrintGCDetails && Verbose) {
1205 gclog_or_tty->print(" " SIZE_FORMAT
1206 "->" SIZE_FORMAT
1207 "(" SIZE_FORMAT ")",
1208 prev_used, used(), capacity());
1209 } else {
1210 gclog_or_tty->print(" " SIZE_FORMAT "K"
1211 "->" SIZE_FORMAT "K"
1212 "(" SIZE_FORMAT "K)",
1213 prev_used / K, used() / K, capacity() / K);
1214 }
1215 }
1216
1217 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1218 private:
1219 bool _full;
1220 public:
1221 void do_generation(Generation* gen) {
1222 gen->gc_prologue(_full);
1223 }
1224 GenGCPrologueClosure(bool full) : _full(full) {};
1225 };
1226
1227 void GenCollectedHeap::gc_prologue(bool full) {
1228 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1229
1230 always_do_update_barrier = false;
1231 // Fill TLAB's and such
1232 CollectedHeap::accumulate_statistics_all_tlabs();
1233 ensure_parsability(true); // retire TLABs
1234
1235 // Walk generations
1236 GenGCPrologueClosure blk(full);
1237 generation_iterate(&blk, false); // not old-to-young.
1238 };
1239
1240 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1241 private:
1242 bool _full;
1243 public:
1244 void do_generation(Generation* gen) {
1245 gen->gc_epilogue(_full);
1246 }
1247 GenGCEpilogueClosure(bool full) : _full(full) {};
1248 };
1249
1250 void GenCollectedHeap::gc_epilogue(bool full) {
1251 #ifdef COMPILER2
1252 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1253 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1254 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1255 #endif /* COMPILER2 */
1256
1257 resize_all_tlabs();
1258
1259 GenGCEpilogueClosure blk(full);
1260 generation_iterate(&blk, false); // not old-to-young.
1261
1262 if (!CleanChunkPoolAsync) {
1263 Chunk::clean_chunk_pool();
1264 }
1265
1266 MetaspaceCounters::update_performance_counters();
1267 CompressedClassSpaceCounters::update_performance_counters();
1268
1269 always_do_update_barrier = UseConcMarkSweepGC;
1270 };
1271
1272 #ifndef PRODUCT
1273 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1274 private:
1275 public:
1276 void do_generation(Generation* gen) {
1277 gen->record_spaces_top();
1278 }
1279 };
1280
1281 void GenCollectedHeap::record_gen_tops_before_GC() {
1282 if (ZapUnusedHeapArea) {
1283 GenGCSaveTopsBeforeGCClosure blk;
1284 generation_iterate(&blk, false); // not old-to-young.
1285 }
1286 }
1287 #endif // not PRODUCT
1288
1289 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1290 public:
1291 void do_generation(Generation* gen) {
1292 gen->ensure_parsability();
1293 }
1294 };
1295
1296 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1297 CollectedHeap::ensure_parsability(retire_tlabs);
1298 GenEnsureParsabilityClosure ep_cl;
1299 generation_iterate(&ep_cl, false);
1300 }
1301
1302 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1303 oop obj,
1304 size_t obj_size) {
1305 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1306 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1307 HeapWord* result = NULL;
1308
1309 result = old_gen->expand_and_allocate(obj_size, false);
1310
1311 if (result != NULL) {
1312 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1313 }
1314 return oop(result);
1315 }
1316
1317 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1318 jlong _time; // in ms
1319 jlong _now; // in ms
1320
1321 public:
1322 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1323
1324 jlong time() { return _time; }
1325
1326 void do_generation(Generation* gen) {
1327 _time = MIN2(_time, gen->time_of_last_gc(_now));
1328 }
1329 };
1330
1331 jlong GenCollectedHeap::millis_since_last_gc() {
1332 // We need a monotonically non-decreasing time in ms but
1333 // os::javaTimeMillis() does not guarantee monotonicity.
1334 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1335 GenTimeOfLastGCClosure tolgc_cl(now);
1336 // iterate over generations getting the oldest
1337 // time that a generation was collected
1338 generation_iterate(&tolgc_cl, false);
1339
1340 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1341 // provided the underlying platform provides such a time source
1342 // (and it is bug free). So we still have to guard against getting
1343 // back a time later than 'now'.
1344 jlong retVal = now - tolgc_cl.time();
1345 if (retVal < 0) {
1346 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1347 return 0;
1348 }
1349 return retVal;
1350 }