Tue, 24 Jun 2014 16:20:15 +0200
8046670: Make CMS metadata aware closures applicable for other collectors
Reviewed-by: ehelin, mgerdin
1 /*
2 * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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23 */
25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc_implementation/shared/collectorCounters.hpp"
31 #include "gc_implementation/shared/gcTrace.hpp"
32 #include "gc_implementation/shared/gcTraceTime.hpp"
33 #include "gc_implementation/shared/vmGCOperations.hpp"
34 #include "gc_interface/collectedHeap.inline.hpp"
35 #include "memory/filemap.hpp"
36 #include "memory/gcLocker.inline.hpp"
37 #include "memory/genCollectedHeap.hpp"
38 #include "memory/genOopClosures.inline.hpp"
39 #include "memory/generation.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 "oops/oop.inline2.hpp"
46 #include "runtime/biasedLocking.hpp"
47 #include "runtime/fprofiler.hpp"
48 #include "runtime/handles.hpp"
49 #include "runtime/handles.inline.hpp"
50 #include "runtime/java.hpp"
51 #include "runtime/vmThread.hpp"
52 #include "services/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
61 GenCollectedHeap* GenCollectedHeap::_gch;
62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
64 // The set of potentially parallel tasks in strong root scanning.
65 enum GCH_process_strong_roots_tasks {
66 // We probably want to parallelize both of these internally, but for now...
67 GCH_PS_younger_gens,
68 // Leave this one last.
69 GCH_PS_NumElements
70 };
72 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
73 SharedHeap(policy),
74 _gen_policy(policy),
75 _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
76 _full_collections_completed(0)
77 {
78 if (_gen_process_strong_tasks == NULL ||
79 !_gen_process_strong_tasks->valid()) {
80 vm_exit_during_initialization("Failed necessary allocation.");
81 }
82 assert(policy != NULL, "Sanity check");
83 }
85 jint GenCollectedHeap::initialize() {
86 CollectedHeap::pre_initialize();
88 int i;
89 _n_gens = gen_policy()->number_of_generations();
91 // While there are no constraints in the GC code that HeapWordSize
92 // be any particular value, there are multiple other areas in the
93 // system which believe this to be true (e.g. oop->object_size in some
94 // cases incorrectly returns the size in wordSize units rather than
95 // HeapWordSize).
96 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
98 // The heap must be at least as aligned as generations.
99 size_t gen_alignment = Generation::GenGrain;
101 _gen_specs = gen_policy()->generations();
103 // Make sure the sizes are all aligned.
104 for (i = 0; i < _n_gens; i++) {
105 _gen_specs[i]->align(gen_alignment);
106 }
108 // Allocate space for the heap.
110 char* heap_address;
111 size_t total_reserved = 0;
112 int n_covered_regions = 0;
113 ReservedSpace heap_rs;
115 size_t heap_alignment = collector_policy()->heap_alignment();
117 heap_address = allocate(heap_alignment, &total_reserved,
118 &n_covered_regions, &heap_rs);
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 }
126 _reserved = MemRegion((HeapWord*)heap_rs.base(),
127 (HeapWord*)(heap_rs.base() + heap_rs.size()));
129 // It is important to do this in a way such that concurrent readers can't
130 // temporarily think somethings in the heap. (Seen this happen in asserts.)
131 _reserved.set_word_size(0);
132 _reserved.set_start((HeapWord*)heap_rs.base());
133 size_t actual_heap_size = heap_rs.size();
134 _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
136 _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
137 set_barrier_set(rem_set()->bs());
139 _gch = this;
141 for (i = 0; i < _n_gens; i++) {
142 ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
143 _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
144 heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
145 }
146 clear_incremental_collection_failed();
148 #if INCLUDE_ALL_GCS
149 // If we are running CMS, create the collector responsible
150 // for collecting the CMS generations.
151 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
152 bool success = create_cms_collector();
153 if (!success) return JNI_ENOMEM;
154 }
155 #endif // INCLUDE_ALL_GCS
157 return JNI_OK;
158 }
161 char* GenCollectedHeap::allocate(size_t alignment,
162 size_t* _total_reserved,
163 int* _n_covered_regions,
164 ReservedSpace* heap_rs){
165 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
166 "the maximum representable size";
168 // Now figure out the total size.
169 size_t total_reserved = 0;
170 int n_covered_regions = 0;
171 const size_t pageSize = UseLargePages ?
172 os::large_page_size() : os::vm_page_size();
174 assert(alignment % pageSize == 0, "Must be");
176 for (int i = 0; i < _n_gens; i++) {
177 total_reserved += _gen_specs[i]->max_size();
178 if (total_reserved < _gen_specs[i]->max_size()) {
179 vm_exit_during_initialization(overflow_msg);
180 }
181 n_covered_regions += _gen_specs[i]->n_covered_regions();
182 }
183 assert(total_reserved % alignment == 0,
184 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
185 SIZE_FORMAT, total_reserved, alignment));
187 // Needed until the cardtable is fixed to have the right number
188 // of covered regions.
189 n_covered_regions += 2;
191 *_total_reserved = total_reserved;
192 *_n_covered_regions = n_covered_regions;
194 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
195 return heap_rs->base();
196 }
199 void GenCollectedHeap::post_initialize() {
200 SharedHeap::post_initialize();
201 TwoGenerationCollectorPolicy *policy =
202 (TwoGenerationCollectorPolicy *)collector_policy();
203 guarantee(policy->is_two_generation_policy(), "Illegal policy type");
204 DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
205 assert(def_new_gen->kind() == Generation::DefNew ||
206 def_new_gen->kind() == Generation::ParNew ||
207 def_new_gen->kind() == Generation::ASParNew,
208 "Wrong generation kind");
210 Generation* old_gen = get_gen(1);
211 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
212 old_gen->kind() == Generation::ASConcurrentMarkSweep ||
213 old_gen->kind() == Generation::MarkSweepCompact,
214 "Wrong generation kind");
216 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
217 old_gen->capacity(),
218 def_new_gen->from()->capacity());
219 policy->initialize_gc_policy_counters();
220 }
222 void GenCollectedHeap::ref_processing_init() {
223 SharedHeap::ref_processing_init();
224 for (int i = 0; i < _n_gens; i++) {
225 _gens[i]->ref_processor_init();
226 }
227 }
229 size_t GenCollectedHeap::capacity() const {
230 size_t res = 0;
231 for (int i = 0; i < _n_gens; i++) {
232 res += _gens[i]->capacity();
233 }
234 return res;
235 }
237 size_t GenCollectedHeap::used() const {
238 size_t res = 0;
239 for (int i = 0; i < _n_gens; i++) {
240 res += _gens[i]->used();
241 }
242 return res;
243 }
245 // Save the "used_region" for generations level and lower.
246 void GenCollectedHeap::save_used_regions(int level) {
247 assert(level < _n_gens, "Illegal level parameter");
248 for (int i = level; i >= 0; i--) {
249 _gens[i]->save_used_region();
250 }
251 }
253 size_t GenCollectedHeap::max_capacity() const {
254 size_t res = 0;
255 for (int i = 0; i < _n_gens; i++) {
256 res += _gens[i]->max_capacity();
257 }
258 return res;
259 }
261 // Update the _full_collections_completed counter
262 // at the end of a stop-world full GC.
263 unsigned int GenCollectedHeap::update_full_collections_completed() {
264 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
265 assert(_full_collections_completed <= _total_full_collections,
266 "Can't complete more collections than were started");
267 _full_collections_completed = _total_full_collections;
268 ml.notify_all();
269 return _full_collections_completed;
270 }
272 // Update the _full_collections_completed counter, as appropriate,
273 // at the end of a concurrent GC cycle. Note the conditional update
274 // below to allow this method to be called by a concurrent collector
275 // without synchronizing in any manner with the VM thread (which
276 // may already have initiated a STW full collection "concurrently").
277 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
278 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
279 assert((_full_collections_completed <= _total_full_collections) &&
280 (count <= _total_full_collections),
281 "Can't complete more collections than were started");
282 if (count > _full_collections_completed) {
283 _full_collections_completed = count;
284 ml.notify_all();
285 }
286 return _full_collections_completed;
287 }
290 #ifndef PRODUCT
291 // Override of memory state checking method in CollectedHeap:
292 // Some collectors (CMS for example) can't have badHeapWordVal written
293 // in the first two words of an object. (For instance , in the case of
294 // CMS these words hold state used to synchronize between certain
295 // (concurrent) GC steps and direct allocating mutators.)
296 // The skip_header_HeapWords() method below, allows us to skip
297 // over the requisite number of HeapWord's. Note that (for
298 // generational collectors) this means that those many words are
299 // skipped in each object, irrespective of the generation in which
300 // that object lives. The resultant loss of precision seems to be
301 // harmless and the pain of avoiding that imprecision appears somewhat
302 // higher than we are prepared to pay for such rudimentary debugging
303 // support.
304 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
305 size_t size) {
306 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
307 // We are asked to check a size in HeapWords,
308 // but the memory is mangled in juint words.
309 juint* start = (juint*) (addr + skip_header_HeapWords());
310 juint* end = (juint*) (addr + size);
311 for (juint* slot = start; slot < end; slot += 1) {
312 assert(*slot == badHeapWordVal,
313 "Found non badHeapWordValue in pre-allocation check");
314 }
315 }
316 }
317 #endif
319 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
320 bool is_tlab,
321 bool first_only) {
322 HeapWord* res;
323 for (int i = 0; i < _n_gens; i++) {
324 if (_gens[i]->should_allocate(size, is_tlab)) {
325 res = _gens[i]->allocate(size, is_tlab);
326 if (res != NULL) return res;
327 else if (first_only) break;
328 }
329 }
330 // Otherwise...
331 return NULL;
332 }
334 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
335 bool* gc_overhead_limit_was_exceeded) {
336 return collector_policy()->mem_allocate_work(size,
337 false /* is_tlab */,
338 gc_overhead_limit_was_exceeded);
339 }
341 bool GenCollectedHeap::must_clear_all_soft_refs() {
342 return _gc_cause == GCCause::_last_ditch_collection;
343 }
345 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
346 return UseConcMarkSweepGC &&
347 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
348 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
349 }
351 void GenCollectedHeap::do_collection(bool full,
352 bool clear_all_soft_refs,
353 size_t size,
354 bool is_tlab,
355 int max_level) {
356 bool prepared_for_verification = false;
357 ResourceMark rm;
358 DEBUG_ONLY(Thread* my_thread = Thread::current();)
360 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
361 assert(my_thread->is_VM_thread() ||
362 my_thread->is_ConcurrentGC_thread(),
363 "incorrect thread type capability");
364 assert(Heap_lock->is_locked(),
365 "the requesting thread should have the Heap_lock");
366 guarantee(!is_gc_active(), "collection is not reentrant");
367 assert(max_level < n_gens(), "sanity check");
369 if (GC_locker::check_active_before_gc()) {
370 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
371 }
373 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
374 collector_policy()->should_clear_all_soft_refs();
376 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
378 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
380 print_heap_before_gc();
382 {
383 FlagSetting fl(_is_gc_active, true);
385 bool complete = full && (max_level == (n_gens()-1));
386 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
387 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
388 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
389 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
390 // so we can assume here that the next GC id is what we want.
391 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
393 gc_prologue(complete);
394 increment_total_collections(complete);
396 size_t gch_prev_used = used();
398 int starting_level = 0;
399 if (full) {
400 // Search for the oldest generation which will collect all younger
401 // generations, and start collection loop there.
402 for (int i = max_level; i >= 0; i--) {
403 if (_gens[i]->full_collects_younger_generations()) {
404 starting_level = i;
405 break;
406 }
407 }
408 }
410 bool must_restore_marks_for_biased_locking = false;
412 int max_level_collected = starting_level;
413 for (int i = starting_level; i <= max_level; i++) {
414 if (_gens[i]->should_collect(full, size, is_tlab)) {
415 if (i == n_gens() - 1) { // a major collection is to happen
416 if (!complete) {
417 // The full_collections increment was missed above.
418 increment_total_full_collections();
419 }
420 pre_full_gc_dump(NULL); // do any pre full gc dumps
421 }
422 // Timer for individual generations. Last argument is false: no CR
423 // FIXME: We should try to start the timing earlier to cover more of the GC pause
424 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
425 // so we can assume here that the next GC id is what we want.
426 GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
427 TraceCollectorStats tcs(_gens[i]->counters());
428 TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
430 size_t prev_used = _gens[i]->used();
431 _gens[i]->stat_record()->invocations++;
432 _gens[i]->stat_record()->accumulated_time.start();
434 // Must be done anew before each collection because
435 // a previous collection will do mangling and will
436 // change top of some spaces.
437 record_gen_tops_before_GC();
439 if (PrintGC && Verbose) {
440 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
441 i,
442 _gens[i]->stat_record()->invocations,
443 size*HeapWordSize);
444 }
446 if (VerifyBeforeGC && i >= VerifyGCLevel &&
447 total_collections() >= VerifyGCStartAt) {
448 HandleMark hm; // Discard invalid handles created during verification
449 if (!prepared_for_verification) {
450 prepare_for_verify();
451 prepared_for_verification = true;
452 }
453 Universe::verify(" VerifyBeforeGC:");
454 }
455 COMPILER2_PRESENT(DerivedPointerTable::clear());
457 if (!must_restore_marks_for_biased_locking &&
458 _gens[i]->performs_in_place_marking()) {
459 // We perform this mark word preservation work lazily
460 // because it's only at this point that we know whether we
461 // absolutely have to do it; we want to avoid doing it for
462 // scavenge-only collections where it's unnecessary
463 must_restore_marks_for_biased_locking = true;
464 BiasedLocking::preserve_marks();
465 }
467 // Do collection work
468 {
469 // Note on ref discovery: For what appear to be historical reasons,
470 // GCH enables and disabled (by enqueing) refs discovery.
471 // In the future this should be moved into the generation's
472 // collect method so that ref discovery and enqueueing concerns
473 // are local to a generation. The collect method could return
474 // an appropriate indication in the case that notification on
475 // the ref lock was needed. This will make the treatment of
476 // weak refs more uniform (and indeed remove such concerns
477 // from GCH). XXX
479 HandleMark hm; // Discard invalid handles created during gc
480 save_marks(); // save marks for all gens
481 // We want to discover references, but not process them yet.
482 // This mode is disabled in process_discovered_references if the
483 // generation does some collection work, or in
484 // enqueue_discovered_references if the generation returns
485 // without doing any work.
486 ReferenceProcessor* rp = _gens[i]->ref_processor();
487 // If the discovery of ("weak") refs in this generation is
488 // atomic wrt other collectors in this configuration, we
489 // are guaranteed to have empty discovered ref lists.
490 if (rp->discovery_is_atomic()) {
491 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
492 rp->setup_policy(do_clear_all_soft_refs);
493 } else {
494 // collect() below will enable discovery as appropriate
495 }
496 _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
497 if (!rp->enqueuing_is_done()) {
498 rp->enqueue_discovered_references();
499 } else {
500 rp->set_enqueuing_is_done(false);
501 }
502 rp->verify_no_references_recorded();
503 }
504 max_level_collected = i;
506 // Determine if allocation request was met.
507 if (size > 0) {
508 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
509 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
510 size = 0;
511 }
512 }
513 }
515 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
517 _gens[i]->stat_record()->accumulated_time.stop();
519 update_gc_stats(i, full);
521 if (VerifyAfterGC && i >= VerifyGCLevel &&
522 total_collections() >= VerifyGCStartAt) {
523 HandleMark hm; // Discard invalid handles created during verification
524 Universe::verify(" VerifyAfterGC:");
525 }
527 if (PrintGCDetails) {
528 gclog_or_tty->print(":");
529 _gens[i]->print_heap_change(prev_used);
530 }
531 }
532 }
534 // Update "complete" boolean wrt what actually transpired --
535 // for instance, a promotion failure could have led to
536 // a whole heap collection.
537 complete = complete || (max_level_collected == n_gens() - 1);
539 if (complete) { // We did a "major" collection
540 // FIXME: See comment at pre_full_gc_dump call
541 post_full_gc_dump(NULL); // do any post full gc dumps
542 }
544 if (PrintGCDetails) {
545 print_heap_change(gch_prev_used);
547 // Print metaspace info for full GC with PrintGCDetails flag.
548 if (complete) {
549 MetaspaceAux::print_metaspace_change(metadata_prev_used);
550 }
551 }
553 for (int j = max_level_collected; j >= 0; j -= 1) {
554 // Adjust generation sizes.
555 _gens[j]->compute_new_size();
556 }
558 if (complete) {
559 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
560 ClassLoaderDataGraph::purge();
561 MetaspaceAux::verify_metrics();
562 // Resize the metaspace capacity after full collections
563 MetaspaceGC::compute_new_size();
564 update_full_collections_completed();
565 }
567 // Track memory usage and detect low memory after GC finishes
568 MemoryService::track_memory_usage();
570 gc_epilogue(complete);
572 if (must_restore_marks_for_biased_locking) {
573 BiasedLocking::restore_marks();
574 }
575 }
577 AdaptiveSizePolicy* sp = gen_policy()->size_policy();
578 AdaptiveSizePolicyOutput(sp, total_collections());
580 print_heap_after_gc();
582 #ifdef TRACESPINNING
583 ParallelTaskTerminator::print_termination_counts();
584 #endif
585 }
587 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
588 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
589 }
591 void GenCollectedHeap::set_par_threads(uint t) {
592 SharedHeap::set_par_threads(t);
593 _gen_process_strong_tasks->set_n_threads(t);
594 }
596 void GenCollectedHeap::
597 gen_process_strong_roots(int level,
598 bool younger_gens_as_roots,
599 bool activate_scope,
600 SharedHeap::ScanningOption so,
601 OopsInGenClosure* not_older_gens,
602 OopsInGenClosure* older_gens,
603 KlassClosure* klass_closure) {
604 // General strong roots.
606 SharedHeap::process_strong_roots(activate_scope, so,
607 not_older_gens, klass_closure);
609 if (younger_gens_as_roots) {
610 if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
611 for (int i = 0; i < level; i++) {
612 not_older_gens->set_generation(_gens[i]);
613 _gens[i]->oop_iterate(not_older_gens);
614 }
615 not_older_gens->reset_generation();
616 }
617 }
618 // When collection is parallel, all threads get to cooperate to do
619 // older-gen scanning.
620 for (int i = level+1; i < _n_gens; i++) {
621 older_gens->set_generation(_gens[i]);
622 rem_set()->younger_refs_iterate(_gens[i], older_gens);
623 older_gens->reset_generation();
624 }
626 _gen_process_strong_tasks->all_tasks_completed();
627 }
629 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
630 SharedHeap::process_weak_roots(root_closure);
631 // "Local" "weak" refs
632 for (int i = 0; i < _n_gens; i++) {
633 _gens[i]->ref_processor()->weak_oops_do(root_closure);
634 }
635 }
637 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
638 void GenCollectedHeap:: \
639 oop_since_save_marks_iterate(int level, \
640 OopClosureType* cur, \
641 OopClosureType* older) { \
642 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
643 for (int i = level+1; i < n_gens(); i++) { \
644 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
645 } \
646 }
648 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
650 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
652 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
653 for (int i = level; i < _n_gens; i++) {
654 if (!_gens[i]->no_allocs_since_save_marks()) return false;
655 }
656 return true;
657 }
659 bool GenCollectedHeap::supports_inline_contig_alloc() const {
660 return _gens[0]->supports_inline_contig_alloc();
661 }
663 HeapWord** GenCollectedHeap::top_addr() const {
664 return _gens[0]->top_addr();
665 }
667 HeapWord** GenCollectedHeap::end_addr() const {
668 return _gens[0]->end_addr();
669 }
671 size_t GenCollectedHeap::unsafe_max_alloc() {
672 return _gens[0]->unsafe_max_alloc_nogc();
673 }
675 // public collection interfaces
677 void GenCollectedHeap::collect(GCCause::Cause cause) {
678 if (should_do_concurrent_full_gc(cause)) {
679 #if INCLUDE_ALL_GCS
680 // mostly concurrent full collection
681 collect_mostly_concurrent(cause);
682 #else // INCLUDE_ALL_GCS
683 ShouldNotReachHere();
684 #endif // INCLUDE_ALL_GCS
685 } else {
686 #ifdef ASSERT
687 if (cause == GCCause::_scavenge_alot) {
688 // minor collection only
689 collect(cause, 0);
690 } else {
691 // Stop-the-world full collection
692 collect(cause, n_gens() - 1);
693 }
694 #else
695 // Stop-the-world full collection
696 collect(cause, n_gens() - 1);
697 #endif
698 }
699 }
701 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
702 // The caller doesn't have the Heap_lock
703 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
704 MutexLocker ml(Heap_lock);
705 collect_locked(cause, max_level);
706 }
708 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
709 // The caller has the Heap_lock
710 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
711 collect_locked(cause, n_gens() - 1);
712 }
714 // this is the private collection interface
715 // The Heap_lock is expected to be held on entry.
717 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
718 // Read the GC count while holding the Heap_lock
719 unsigned int gc_count_before = total_collections();
720 unsigned int full_gc_count_before = total_full_collections();
721 {
722 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
723 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
724 cause, max_level);
725 VMThread::execute(&op);
726 }
727 }
729 #if INCLUDE_ALL_GCS
730 bool GenCollectedHeap::create_cms_collector() {
732 assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
733 (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)),
734 "Unexpected generation kinds");
735 // Skip two header words in the block content verification
736 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
737 CMSCollector* collector = new CMSCollector(
738 (ConcurrentMarkSweepGeneration*)_gens[1],
739 _rem_set->as_CardTableRS(),
740 (ConcurrentMarkSweepPolicy*) collector_policy());
742 if (collector == NULL || !collector->completed_initialization()) {
743 if (collector) {
744 delete collector; // Be nice in embedded situation
745 }
746 vm_shutdown_during_initialization("Could not create CMS collector");
747 return false;
748 }
749 return true; // success
750 }
752 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
753 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
755 MutexLocker ml(Heap_lock);
756 // Read the GC counts while holding the Heap_lock
757 unsigned int full_gc_count_before = total_full_collections();
758 unsigned int gc_count_before = total_collections();
759 {
760 MutexUnlocker mu(Heap_lock);
761 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
762 VMThread::execute(&op);
763 }
764 }
765 #endif // INCLUDE_ALL_GCS
767 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
768 do_full_collection(clear_all_soft_refs, _n_gens - 1);
769 }
771 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
772 int max_level) {
773 int local_max_level;
774 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
775 gc_cause() == GCCause::_gc_locker) {
776 local_max_level = 0;
777 } else {
778 local_max_level = max_level;
779 }
781 do_collection(true /* full */,
782 clear_all_soft_refs /* clear_all_soft_refs */,
783 0 /* size */,
784 false /* is_tlab */,
785 local_max_level /* max_level */);
786 // Hack XXX FIX ME !!!
787 // A scavenge may not have been attempted, or may have
788 // been attempted and failed, because the old gen was too full
789 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
790 incremental_collection_will_fail(false /* don't consult_young */)) {
791 if (PrintGCDetails) {
792 gclog_or_tty->print_cr("GC locker: Trying a full collection "
793 "because scavenge failed");
794 }
795 // This time allow the old gen to be collected as well
796 do_collection(true /* full */,
797 clear_all_soft_refs /* clear_all_soft_refs */,
798 0 /* size */,
799 false /* is_tlab */,
800 n_gens() - 1 /* max_level */);
801 }
802 }
804 bool GenCollectedHeap::is_in_young(oop p) {
805 bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
806 assert(result == _gens[0]->is_in_reserved(p),
807 err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, p2i((void*)p)));
808 return result;
809 }
811 // Returns "TRUE" iff "p" points into the committed areas of the heap.
812 bool GenCollectedHeap::is_in(const void* p) const {
813 #ifndef ASSERT
814 guarantee(VerifyBeforeGC ||
815 VerifyDuringGC ||
816 VerifyBeforeExit ||
817 VerifyDuringStartup ||
818 PrintAssembly ||
819 tty->count() != 0 || // already printing
820 VerifyAfterGC ||
821 VMError::fatal_error_in_progress(), "too expensive");
823 #endif
824 // This might be sped up with a cache of the last generation that
825 // answered yes.
826 for (int i = 0; i < _n_gens; i++) {
827 if (_gens[i]->is_in(p)) return true;
828 }
829 // Otherwise...
830 return false;
831 }
833 #ifdef ASSERT
834 // Don't implement this by using is_in_young(). This method is used
835 // in some cases to check that is_in_young() is correct.
836 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
837 assert(is_in_reserved(p) || p == NULL,
838 "Does not work if address is non-null and outside of the heap");
839 return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
840 }
841 #endif
843 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
844 for (int i = 0; i < _n_gens; i++) {
845 _gens[i]->oop_iterate(cl);
846 }
847 }
849 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
850 for (int i = 0; i < _n_gens; i++) {
851 _gens[i]->object_iterate(cl);
852 }
853 }
855 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
856 for (int i = 0; i < _n_gens; i++) {
857 _gens[i]->safe_object_iterate(cl);
858 }
859 }
861 Space* GenCollectedHeap::space_containing(const void* addr) const {
862 for (int i = 0; i < _n_gens; i++) {
863 Space* res = _gens[i]->space_containing(addr);
864 if (res != NULL) return res;
865 }
866 // Otherwise...
867 assert(false, "Could not find containing space");
868 return NULL;
869 }
872 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
873 assert(is_in_reserved(addr), "block_start of address outside of heap");
874 for (int i = 0; i < _n_gens; i++) {
875 if (_gens[i]->is_in_reserved(addr)) {
876 assert(_gens[i]->is_in(addr),
877 "addr should be in allocated part of generation");
878 return _gens[i]->block_start(addr);
879 }
880 }
881 assert(false, "Some generation should contain the address");
882 return NULL;
883 }
885 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
886 assert(is_in_reserved(addr), "block_size of address outside of heap");
887 for (int i = 0; i < _n_gens; i++) {
888 if (_gens[i]->is_in_reserved(addr)) {
889 assert(_gens[i]->is_in(addr),
890 "addr should be in allocated part of generation");
891 return _gens[i]->block_size(addr);
892 }
893 }
894 assert(false, "Some generation should contain the address");
895 return 0;
896 }
898 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
899 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
900 assert(block_start(addr) == addr, "addr must be a block start");
901 for (int i = 0; i < _n_gens; i++) {
902 if (_gens[i]->is_in_reserved(addr)) {
903 return _gens[i]->block_is_obj(addr);
904 }
905 }
906 assert(false, "Some generation should contain the address");
907 return false;
908 }
910 bool GenCollectedHeap::supports_tlab_allocation() const {
911 for (int i = 0; i < _n_gens; i += 1) {
912 if (_gens[i]->supports_tlab_allocation()) {
913 return true;
914 }
915 }
916 return false;
917 }
919 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
920 size_t result = 0;
921 for (int i = 0; i < _n_gens; i += 1) {
922 if (_gens[i]->supports_tlab_allocation()) {
923 result += _gens[i]->tlab_capacity();
924 }
925 }
926 return result;
927 }
929 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
930 size_t result = 0;
931 for (int i = 0; i < _n_gens; i += 1) {
932 if (_gens[i]->supports_tlab_allocation()) {
933 result += _gens[i]->tlab_used();
934 }
935 }
936 return result;
937 }
939 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
940 size_t result = 0;
941 for (int i = 0; i < _n_gens; i += 1) {
942 if (_gens[i]->supports_tlab_allocation()) {
943 result += _gens[i]->unsafe_max_tlab_alloc();
944 }
945 }
946 return result;
947 }
949 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
950 bool gc_overhead_limit_was_exceeded;
951 return collector_policy()->mem_allocate_work(size /* size */,
952 true /* is_tlab */,
953 &gc_overhead_limit_was_exceeded);
954 }
956 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
957 // from the list headed by "*prev_ptr".
958 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
959 bool first = true;
960 size_t min_size = 0; // "first" makes this conceptually infinite.
961 ScratchBlock **smallest_ptr, *smallest;
962 ScratchBlock *cur = *prev_ptr;
963 while (cur) {
964 assert(*prev_ptr == cur, "just checking");
965 if (first || cur->num_words < min_size) {
966 smallest_ptr = prev_ptr;
967 smallest = cur;
968 min_size = smallest->num_words;
969 first = false;
970 }
971 prev_ptr = &cur->next;
972 cur = cur->next;
973 }
974 smallest = *smallest_ptr;
975 *smallest_ptr = smallest->next;
976 return smallest;
977 }
979 // Sort the scratch block list headed by res into decreasing size order,
980 // and set "res" to the result.
981 static void sort_scratch_list(ScratchBlock*& list) {
982 ScratchBlock* sorted = NULL;
983 ScratchBlock* unsorted = list;
984 while (unsorted) {
985 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
986 smallest->next = sorted;
987 sorted = smallest;
988 }
989 list = sorted;
990 }
992 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
993 size_t max_alloc_words) {
994 ScratchBlock* res = NULL;
995 for (int i = 0; i < _n_gens; i++) {
996 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
997 }
998 sort_scratch_list(res);
999 return res;
1000 }
1002 void GenCollectedHeap::release_scratch() {
1003 for (int i = 0; i < _n_gens; i++) {
1004 _gens[i]->reset_scratch();
1005 }
1006 }
1008 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1009 void do_generation(Generation* gen) {
1010 gen->prepare_for_verify();
1011 }
1012 };
1014 void GenCollectedHeap::prepare_for_verify() {
1015 ensure_parsability(false); // no need to retire TLABs
1016 GenPrepareForVerifyClosure blk;
1017 generation_iterate(&blk, false);
1018 }
1021 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1022 bool old_to_young) {
1023 if (old_to_young) {
1024 for (int i = _n_gens-1; i >= 0; i--) {
1025 cl->do_generation(_gens[i]);
1026 }
1027 } else {
1028 for (int i = 0; i < _n_gens; i++) {
1029 cl->do_generation(_gens[i]);
1030 }
1031 }
1032 }
1034 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1035 for (int i = 0; i < _n_gens; i++) {
1036 _gens[i]->space_iterate(cl, true);
1037 }
1038 }
1040 bool GenCollectedHeap::is_maximal_no_gc() const {
1041 for (int i = 0; i < _n_gens; i++) {
1042 if (!_gens[i]->is_maximal_no_gc()) {
1043 return false;
1044 }
1045 }
1046 return true;
1047 }
1049 void GenCollectedHeap::save_marks() {
1050 for (int i = 0; i < _n_gens; i++) {
1051 _gens[i]->save_marks();
1052 }
1053 }
1055 GenCollectedHeap* GenCollectedHeap::heap() {
1056 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1057 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1058 return _gch;
1059 }
1062 void GenCollectedHeap::prepare_for_compaction() {
1063 guarantee(_n_gens = 2, "Wrong number of generations");
1064 Generation* old_gen = _gens[1];
1065 // Start by compacting into same gen.
1066 CompactPoint cp(old_gen, NULL, NULL);
1067 old_gen->prepare_for_compaction(&cp);
1068 Generation* young_gen = _gens[0];
1069 young_gen->prepare_for_compaction(&cp);
1070 }
1072 GCStats* GenCollectedHeap::gc_stats(int level) const {
1073 return _gens[level]->gc_stats();
1074 }
1076 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1077 for (int i = _n_gens-1; i >= 0; i--) {
1078 Generation* g = _gens[i];
1079 if (!silent) {
1080 gclog_or_tty->print("%s", g->name());
1081 gclog_or_tty->print(" ");
1082 }
1083 g->verify();
1084 }
1085 if (!silent) {
1086 gclog_or_tty->print("remset ");
1087 }
1088 rem_set()->verify();
1089 }
1091 void GenCollectedHeap::print_on(outputStream* st) const {
1092 for (int i = 0; i < _n_gens; i++) {
1093 _gens[i]->print_on(st);
1094 }
1095 MetaspaceAux::print_on(st);
1096 }
1098 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1099 if (workers() != NULL) {
1100 workers()->threads_do(tc);
1101 }
1102 #if INCLUDE_ALL_GCS
1103 if (UseConcMarkSweepGC) {
1104 ConcurrentMarkSweepThread::threads_do(tc);
1105 }
1106 #endif // INCLUDE_ALL_GCS
1107 }
1109 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1110 #if INCLUDE_ALL_GCS
1111 if (UseParNewGC) {
1112 workers()->print_worker_threads_on(st);
1113 }
1114 if (UseConcMarkSweepGC) {
1115 ConcurrentMarkSweepThread::print_all_on(st);
1116 }
1117 #endif // INCLUDE_ALL_GCS
1118 }
1120 void GenCollectedHeap::print_on_error(outputStream* st) const {
1121 this->CollectedHeap::print_on_error(st);
1123 #if INCLUDE_ALL_GCS
1124 if (UseConcMarkSweepGC) {
1125 st->cr();
1126 CMSCollector::print_on_error(st);
1127 }
1128 #endif // INCLUDE_ALL_GCS
1129 }
1131 void GenCollectedHeap::print_tracing_info() const {
1132 if (TraceGen0Time) {
1133 get_gen(0)->print_summary_info();
1134 }
1135 if (TraceGen1Time) {
1136 get_gen(1)->print_summary_info();
1137 }
1138 }
1140 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1141 if (PrintGCDetails && Verbose) {
1142 gclog_or_tty->print(" " SIZE_FORMAT
1143 "->" SIZE_FORMAT
1144 "(" SIZE_FORMAT ")",
1145 prev_used, used(), capacity());
1146 } else {
1147 gclog_or_tty->print(" " SIZE_FORMAT "K"
1148 "->" SIZE_FORMAT "K"
1149 "(" SIZE_FORMAT "K)",
1150 prev_used / K, used() / K, capacity() / K);
1151 }
1152 }
1154 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1155 private:
1156 bool _full;
1157 public:
1158 void do_generation(Generation* gen) {
1159 gen->gc_prologue(_full);
1160 }
1161 GenGCPrologueClosure(bool full) : _full(full) {};
1162 };
1164 void GenCollectedHeap::gc_prologue(bool full) {
1165 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1167 always_do_update_barrier = false;
1168 // Fill TLAB's and such
1169 CollectedHeap::accumulate_statistics_all_tlabs();
1170 ensure_parsability(true); // retire TLABs
1172 // Walk generations
1173 GenGCPrologueClosure blk(full);
1174 generation_iterate(&blk, false); // not old-to-young.
1175 };
1177 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1178 private:
1179 bool _full;
1180 public:
1181 void do_generation(Generation* gen) {
1182 gen->gc_epilogue(_full);
1183 }
1184 GenGCEpilogueClosure(bool full) : _full(full) {};
1185 };
1187 void GenCollectedHeap::gc_epilogue(bool full) {
1188 #ifdef COMPILER2
1189 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1190 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1191 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1192 #endif /* COMPILER2 */
1194 resize_all_tlabs();
1196 GenGCEpilogueClosure blk(full);
1197 generation_iterate(&blk, false); // not old-to-young.
1199 if (!CleanChunkPoolAsync) {
1200 Chunk::clean_chunk_pool();
1201 }
1203 MetaspaceCounters::update_performance_counters();
1204 CompressedClassSpaceCounters::update_performance_counters();
1206 always_do_update_barrier = UseConcMarkSweepGC;
1207 };
1209 #ifndef PRODUCT
1210 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1211 private:
1212 public:
1213 void do_generation(Generation* gen) {
1214 gen->record_spaces_top();
1215 }
1216 };
1218 void GenCollectedHeap::record_gen_tops_before_GC() {
1219 if (ZapUnusedHeapArea) {
1220 GenGCSaveTopsBeforeGCClosure blk;
1221 generation_iterate(&blk, false); // not old-to-young.
1222 }
1223 }
1224 #endif // not PRODUCT
1226 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1227 public:
1228 void do_generation(Generation* gen) {
1229 gen->ensure_parsability();
1230 }
1231 };
1233 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1234 CollectedHeap::ensure_parsability(retire_tlabs);
1235 GenEnsureParsabilityClosure ep_cl;
1236 generation_iterate(&ep_cl, false);
1237 }
1239 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1240 oop obj,
1241 size_t obj_size) {
1242 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1243 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1244 HeapWord* result = NULL;
1246 result = old_gen->expand_and_allocate(obj_size, false);
1248 if (result != NULL) {
1249 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1250 }
1251 return oop(result);
1252 }
1254 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1255 jlong _time; // in ms
1256 jlong _now; // in ms
1258 public:
1259 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1261 jlong time() { return _time; }
1263 void do_generation(Generation* gen) {
1264 _time = MIN2(_time, gen->time_of_last_gc(_now));
1265 }
1266 };
1268 jlong GenCollectedHeap::millis_since_last_gc() {
1269 // We need a monotonically non-deccreasing time in ms but
1270 // os::javaTimeMillis() does not guarantee monotonicity.
1271 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1272 GenTimeOfLastGCClosure tolgc_cl(now);
1273 // iterate over generations getting the oldest
1274 // time that a generation was collected
1275 generation_iterate(&tolgc_cl, false);
1277 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1278 // provided the underlying platform provides such a time source
1279 // (and it is bug free). So we still have to guard against getting
1280 // back a time later than 'now'.
1281 jlong retVal = now - tolgc_cl.time();
1282 if (retVal < 0) {
1283 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1284 return 0;
1285 }
1286 return retVal;
1287 }