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/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/generationSpec.hpp"
40 #include "memory/resourceArea.hpp"
41 #include "memory/sharedHeap.hpp"
42 #include "memory/space.hpp"
43 #include "oops/oop.inline.hpp"
44 #include "runtime/biasedLocking.hpp"
45 #include "runtime/fprofiler.hpp"
46 #include "runtime/handles.hpp"
47 #include "runtime/handles.inline.hpp"
48 #include "runtime/java.hpp"
49 #include "runtime/vmThread.hpp"
50 #include "services/memoryService.hpp"
51 #include "utilities/vmError.hpp"
52 #include "utilities/workgroup.hpp"
53 #include "utilities/macros.hpp"
54 #if INCLUDE_ALL_GCS
55 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
56 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
57 #endif // INCLUDE_ALL_GCS
58
59 GenCollectedHeap* GenCollectedHeap::_gch;
60 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
61
62 // The set of potentially parallel tasks in root scanning.
63 enum GCH_strong_roots_tasks {
64 // We probably want to parallelize both of these internally, but for now...
65 GCH_PS_younger_gens,
66 // Leave this one last.
67 GCH_PS_NumElements
68 };
69
70 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
71 SharedHeap(policy),
72 _rem_set(NULL),
73 _gen_policy(policy),
74 _gen_process_roots_tasks(new SubTasksDone(GCH_PS_NumElements)),
75 _full_collections_completed(0)
76 {
77 if (_gen_process_roots_tasks == NULL ||
78 !_gen_process_roots_tasks->valid()) {
79 vm_exit_during_initialization("Failed necessary allocation.");
80 }
81 assert(policy != NULL, "Sanity check");
82 }
83
84 jint GenCollectedHeap::initialize() {
85 CollectedHeap::pre_initialize();
86
87 int i;
88 _n_gens = gen_policy()->number_of_generations();
89 assert(_n_gens == 2, "There is no support for more than two generations");
90
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");
97
98 // The heap must be at least as aligned as generations.
99 size_t gen_alignment = Generation::GenGrain;
100
101 _gen_specs = gen_policy()->generations();
102
103 // Make sure the sizes are all aligned.
104 for (i = 0; i < _n_gens; i++) {
105 _gen_specs[i]->align(gen_alignment);
106 }
107
108 // Allocate space for the heap.
109
110 char* heap_address;
111 ReservedSpace heap_rs;
112
113 size_t heap_alignment = collector_policy()->heap_alignment();
114
115 heap_address = allocate(heap_alignment, &heap_rs);
116
117 if (!heap_rs.is_reserved()) {
118 vm_shutdown_during_initialization(
119 "Could not reserve enough space for object heap");
120 return JNI_ENOMEM;
121 }
122
123 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
124
125 _rem_set = collector_policy()->create_rem_set(reserved_region());
126 set_barrier_set(rem_set()->bs());
127
128 _gch = this;
129
130 ReservedSpace young_rs = heap_rs.first_part(_gen_specs[0]->max_size(), false, false);
131 _young_gen = _gen_specs[0]->init(young_rs, 0, rem_set());
132 heap_rs = heap_rs.last_part(_gen_specs[0]->max_size());
133
134 ReservedSpace old_rs = heap_rs.first_part(_gen_specs[1]->max_size(), false, false);
135 _old_gen = _gen_specs[1]->init(old_rs, 1, rem_set());
136 clear_incremental_collection_failed();
137
138 #if INCLUDE_ALL_GCS
139 // If we are running CMS, create the collector responsible
140 // for collecting the CMS generations.
141 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
142 bool success = create_cms_collector();
143 if (!success) return JNI_ENOMEM;
144 }
145 #endif // INCLUDE_ALL_GCS
146
147 return JNI_OK;
148 }
149
150 char* GenCollectedHeap::allocate(size_t alignment,
151 ReservedSpace* heap_rs){
152 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
153 "the maximum representable size";
154
155 // Now figure out the total size.
156 size_t total_reserved = 0;
157 const size_t pageSize = UseLargePages ?
158 os::large_page_size() : os::vm_page_size();
159
160 assert(alignment % pageSize == 0, "Must be");
161
162 for (int i = 0; i < _n_gens; i++) {
163 total_reserved += _gen_specs[i]->max_size();
164 if (total_reserved < _gen_specs[i]->max_size()) {
165 vm_exit_during_initialization(overflow_msg);
166 }
167 }
168 assert(total_reserved % alignment == 0,
169 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
170 SIZE_FORMAT, total_reserved, alignment));
171
172 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
173 return heap_rs->base();
174 }
175
176 void GenCollectedHeap::post_initialize() {
177 SharedHeap::post_initialize();
178 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
179 guarantee(policy->is_generation_policy(), "Illegal policy type");
180 assert((get_gen(0)->kind() == Generation::DefNew) ||
181 (get_gen(0)->kind() == Generation::ParNew),
182 "Wrong youngest generation type");
183 DefNewGeneration* def_new_gen = (DefNewGeneration*)get_gen(0);
184
185 Generation* old_gen = get_gen(1);
186 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
187 old_gen->kind() == Generation::MarkSweepCompact,
188 "Wrong generation kind");
189
190 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
191 old_gen->capacity(),
192 def_new_gen->from()->capacity());
193 policy->initialize_gc_policy_counters();
194 }
195
196 void GenCollectedHeap::ref_processing_init() {
197 SharedHeap::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 if (!UseConcMarkSweepGC) {
314 return false;
315 }
316
317 switch (cause) {
318 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
319 case GCCause::_java_lang_system_gc:
320 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
321 default: return false;
322 }
323 }
324
325 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
326 bool is_tlab, bool run_verification, bool clear_soft_refs,
327 bool restore_marks_for_biased_locking) {
328 // Timer for individual generations. Last argument is false: no CR
329 // FIXME: We should try to start the timing earlier to cover more of the GC pause
330 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
331 // so we can assume here that the next GC id is what we want.
332 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
333 TraceCollectorStats tcs(gen->counters());
334 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
335
336 size_t prev_used = gen->used();
337 gen->stat_record()->invocations++;
338 gen->stat_record()->accumulated_time.start();
339
340 // Must be done anew before each collection because
341 // a previous collection will do mangling and will
342 // change top of some spaces.
343 record_gen_tops_before_GC();
344
345 if (PrintGC && Verbose) {
346 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
347 gen->level(),
348 gen->stat_record()->invocations,
349 size * HeapWordSize);
350 }
351
352 if (run_verification && VerifyBeforeGC) {
353 HandleMark hm; // Discard invalid handles created during verification
354 Universe::verify(" VerifyBeforeGC:");
355 }
356 COMPILER2_PRESENT(DerivedPointerTable::clear());
357
358 if (restore_marks_for_biased_locking) {
359 // We perform this mark word preservation work lazily
360 // because it's only at this point that we know whether we
361 // absolutely have to do it; we want to avoid doing it for
362 // scavenge-only collections where it's unnecessary
363 BiasedLocking::preserve_marks();
364 }
365
366 // Do collection work
367 {
368 // Note on ref discovery: For what appear to be historical reasons,
369 // GCH enables and disabled (by enqueing) refs discovery.
370 // In the future this should be moved into the generation's
371 // collect method so that ref discovery and enqueueing concerns
372 // are local to a generation. The collect method could return
373 // an appropriate indication in the case that notification on
374 // the ref lock was needed. This will make the treatment of
375 // weak refs more uniform (and indeed remove such concerns
376 // from GCH). XXX
377
378 HandleMark hm; // Discard invalid handles created during gc
379 save_marks(); // save marks for all gens
380 // We want to discover references, but not process them yet.
381 // This mode is disabled in process_discovered_references if the
382 // generation does some collection work, or in
383 // enqueue_discovered_references if the generation returns
384 // without doing any work.
385 ReferenceProcessor* rp = gen->ref_processor();
386 // If the discovery of ("weak") refs in this generation is
387 // atomic wrt other collectors in this configuration, we
388 // are guaranteed to have empty discovered ref lists.
389 if (rp->discovery_is_atomic()) {
390 rp->enable_discovery();
391 rp->setup_policy(clear_soft_refs);
392 } else {
393 // collect() below will enable discovery as appropriate
394 }
395 gen->collect(full, clear_soft_refs, size, is_tlab);
396 if (!rp->enqueuing_is_done()) {
397 rp->enqueue_discovered_references();
398 } else {
399 rp->set_enqueuing_is_done(false);
400 }
401 rp->verify_no_references_recorded();
402 }
403
404 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
405
406 gen->stat_record()->accumulated_time.stop();
407
408 update_gc_stats(gen->level(), full);
409
410 if (run_verification && VerifyAfterGC) {
411 HandleMark hm; // Discard invalid handles created during verification
412 Universe::verify(" VerifyAfterGC:");
413 }
414
415 if (PrintGCDetails) {
416 gclog_or_tty->print(":");
417 gen->print_heap_change(prev_used);
418 }
419 }
420
421 void GenCollectedHeap::do_collection(bool full,
422 bool clear_all_soft_refs,
423 size_t size,
424 bool is_tlab,
425 int max_level) {
426 ResourceMark rm;
427 DEBUG_ONLY(Thread* my_thread = Thread::current();)
428
429 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
430 assert(my_thread->is_VM_thread() ||
431 my_thread->is_ConcurrentGC_thread(),
432 "incorrect thread type capability");
433 assert(Heap_lock->is_locked(),
434 "the requesting thread should have the Heap_lock");
435 guarantee(!is_gc_active(), "collection is not reentrant");
436 assert(max_level < n_gens(), "sanity check");
437
438 if (GC_locker::check_active_before_gc()) {
439 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
440 }
441
442 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
443 collector_policy()->should_clear_all_soft_refs();
444
445 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
446
447 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
448
449 print_heap_before_gc();
450
451 {
452 FlagSetting fl(_is_gc_active, true);
453
454 bool complete = full && (max_level == (n_gens()-1));
455 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
456 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
457 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
458 // so we can assume here that the next GC id is what we want.
459 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
460
461 gc_prologue(complete);
462 increment_total_collections(complete);
463
464 size_t gch_prev_used = used();
465 bool run_verification = total_collections() >= VerifyGCStartAt;
466
467 bool prepared_for_verification = false;
468 int max_level_collected = 0;
469 bool old_collects_young = (max_level == 1) &&
470 full &&
471 _old_gen->full_collects_younger_generations();
472 if (!old_collects_young &&
473 _young_gen->should_collect(full, size, is_tlab)) {
474 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
475 prepare_for_verify();
476 prepared_for_verification = true;
477 }
478
479 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
480 collect_generation(_young_gen,
481 full,
482 size,
483 is_tlab,
484 run_verification && VerifyGCLevel <= 0,
485 do_clear_all_soft_refs,
486 false);
487
488 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
489 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
490 // Allocation request was met by young GC.
491 size = 0;
492 }
493 }
494
495 bool must_restore_marks_for_biased_locking = false;
496
497 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
498 if (!complete) {
499 // The full_collections increment was missed above.
500 increment_total_full_collections();
501 }
502
503 pre_full_gc_dump(NULL); // do any pre full gc dumps
504
505 if (!prepared_for_verification && run_verification &&
506 VerifyGCLevel <= 1 && VerifyBeforeGC) {
507 prepare_for_verify();
508 }
509
510 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
511 collect_generation(_old_gen,
512 full,
513 size,
514 is_tlab,
515 run_verification && VerifyGCLevel <= 1,
516 do_clear_all_soft_refs,
517 true);
518
519 must_restore_marks_for_biased_locking = true;
520 max_level_collected = 1;
521 }
522
523 // Update "complete" boolean wrt what actually transpired --
524 // for instance, a promotion failure could have led to
525 // a whole heap collection.
526 complete = complete || (max_level_collected == n_gens() - 1);
527
528 if (complete) { // We did a "major" collection
529 // FIXME: See comment at pre_full_gc_dump call
530 post_full_gc_dump(NULL); // do any post full gc dumps
531 }
532
533 if (PrintGCDetails) {
534 print_heap_change(gch_prev_used);
535
536 // Print metaspace info for full GC with PrintGCDetails flag.
537 if (complete) {
538 MetaspaceAux::print_metaspace_change(metadata_prev_used);
539 }
540 }
541
542 // Adjust generation sizes.
543 if (max_level_collected == 1) {
544 _old_gen->compute_new_size();
545 }
546 _young_gen->compute_new_size();
547
548 if (complete) {
549 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
550 ClassLoaderDataGraph::purge();
551 MetaspaceAux::verify_metrics();
552 // Resize the metaspace capacity after full collections
553 MetaspaceGC::compute_new_size();
554 update_full_collections_completed();
555 }
556
557 // Track memory usage and detect low memory after GC finishes
558 MemoryService::track_memory_usage();
559
560 gc_epilogue(complete);
561
562 if (must_restore_marks_for_biased_locking) {
563 BiasedLocking::restore_marks();
564 }
565 }
566
567 print_heap_after_gc();
568
569 #ifdef TRACESPINNING
570 ParallelTaskTerminator::print_termination_counts();
571 #endif
572 }
573
574 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
575 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
576 }
577
578 void GenCollectedHeap::set_par_threads(uint t) {
579 SharedHeap::set_par_threads(t);
580 _gen_process_roots_tasks->set_n_threads(t);
581 }
582
583 void GenCollectedHeap::
584 gen_process_roots(int level,
585 bool younger_gens_as_roots,
586 bool activate_scope,
587 SharedHeap::ScanningOption so,
588 OopsInGenClosure* not_older_gens,
589 OopsInGenClosure* weak_roots,
590 OopsInGenClosure* older_gens,
591 CLDClosure* cld_closure,
592 CLDClosure* weak_cld_closure,
593 CodeBlobClosure* code_closure) {
594
595 // General roots.
596 SharedHeap::process_roots(activate_scope, so,
597 not_older_gens, weak_roots,
598 cld_closure, weak_cld_closure,
599 code_closure);
600
601 if (younger_gens_as_roots) {
602 if (!_gen_process_roots_tasks->is_task_claimed(GCH_PS_younger_gens)) {
603 if (level == 1) {
604 not_older_gens->set_generation(_young_gen);
605 _young_gen->oop_iterate(not_older_gens);
606 }
607 not_older_gens->reset_generation();
608 }
609 }
610 // When collection is parallel, all threads get to cooperate to do
611 // older-gen scanning.
612 if (level == 0) {
613 older_gens->set_generation(_old_gen);
614 rem_set()->younger_refs_iterate(_old_gen, older_gens);
615 older_gens->reset_generation();
616 }
617
618 _gen_process_roots_tasks->all_tasks_completed();
619 }
620
621 void GenCollectedHeap::
622 gen_process_roots(int level,
623 bool younger_gens_as_roots,
624 bool activate_scope,
625 SharedHeap::ScanningOption so,
626 bool only_strong_roots,
627 OopsInGenClosure* not_older_gens,
628 OopsInGenClosure* older_gens,
629 CLDClosure* cld_closure) {
630
631 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
632
633 bool is_moving_collection = false;
634 if (level == 0 || is_adjust_phase) {
635 // young collections are always moving
636 is_moving_collection = true;
637 }
638
639 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
640 CodeBlobClosure* code_closure = &mark_code_closure;
641
642 gen_process_roots(level,
643 younger_gens_as_roots,
644 activate_scope, so,
645 not_older_gens, only_strong_roots ? NULL : not_older_gens,
646 older_gens,
647 cld_closure, only_strong_roots ? NULL : cld_closure,
648 code_closure);
649
650 }
651
652 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
653 SharedHeap::process_weak_roots(root_closure);
654 // "Local" "weak" refs
655 _young_gen->ref_processor()->weak_oops_do(root_closure);
656 _old_gen->ref_processor()->weak_oops_do(root_closure);
657 }
658
659 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
660 void GenCollectedHeap:: \
661 oop_since_save_marks_iterate(int level, \
662 OopClosureType* cur, \
663 OopClosureType* older) { \
664 if (level == 0) { \
665 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
666 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
667 } else { \
668 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
669 } \
670 }
671
672 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
673
674 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
675
676 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
677 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
678 return false;
679 }
680 return _old_gen->no_allocs_since_save_marks();
681 }
682
683 bool GenCollectedHeap::supports_inline_contig_alloc() const {
684 return _young_gen->supports_inline_contig_alloc();
685 }
686
687 HeapWord** GenCollectedHeap::top_addr() const {
688 return _young_gen->top_addr();
689 }
690
691 HeapWord** GenCollectedHeap::end_addr() const {
692 return _young_gen->end_addr();
693 }
694
695 // public collection interfaces
696
697 void GenCollectedHeap::collect(GCCause::Cause cause) {
698 if (should_do_concurrent_full_gc(cause)) {
699 #if INCLUDE_ALL_GCS
700 // mostly concurrent full collection
701 collect_mostly_concurrent(cause);
702 #else // INCLUDE_ALL_GCS
703 ShouldNotReachHere();
704 #endif // INCLUDE_ALL_GCS
705 } else if (cause == GCCause::_wb_young_gc) {
706 // minor collection for WhiteBox API
707 collect(cause, 0);
708 } else {
709 #ifdef ASSERT
710 if (cause == GCCause::_scavenge_alot) {
711 // minor collection only
712 collect(cause, 0);
713 } else {
714 // Stop-the-world full collection
715 collect(cause, n_gens() - 1);
716 }
717 #else
718 // Stop-the-world full collection
719 collect(cause, n_gens() - 1);
720 #endif
721 }
722 }
723
724 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
725 // The caller doesn't have the Heap_lock
726 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
727 MutexLocker ml(Heap_lock);
728 collect_locked(cause, max_level);
729 }
730
731 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
732 // The caller has the Heap_lock
733 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
734 collect_locked(cause, n_gens() - 1);
735 }
736
737 // this is the private collection interface
738 // The Heap_lock is expected to be held on entry.
739
740 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
741 // Read the GC count while holding the Heap_lock
742 unsigned int gc_count_before = total_collections();
743 unsigned int full_gc_count_before = total_full_collections();
744 {
745 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
746 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
747 cause, max_level);
748 VMThread::execute(&op);
749 }
750 }
751
752 #if INCLUDE_ALL_GCS
753 bool GenCollectedHeap::create_cms_collector() {
754
755 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
756 "Unexpected generation kinds");
757 // Skip two header words in the block content verification
758 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
759 CMSCollector* collector = new CMSCollector(
760 (ConcurrentMarkSweepGeneration*)_old_gen,
761 _rem_set->as_CardTableRS(),
762 (ConcurrentMarkSweepPolicy*) collector_policy());
763
764 if (collector == NULL || !collector->completed_initialization()) {
765 if (collector) {
766 delete collector; // Be nice in embedded situation
767 }
768 vm_shutdown_during_initialization("Could not create CMS collector");
769 return false;
770 }
771 return true; // success
772 }
773
774 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
775 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
776
777 MutexLocker ml(Heap_lock);
778 // Read the GC counts while holding the Heap_lock
779 unsigned int full_gc_count_before = total_full_collections();
780 unsigned int gc_count_before = total_collections();
781 {
782 MutexUnlocker mu(Heap_lock);
783 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
784 VMThread::execute(&op);
785 }
786 }
787 #endif // INCLUDE_ALL_GCS
788
789 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
790 do_full_collection(clear_all_soft_refs, _n_gens - 1);
791 }
792
793 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
794 int max_level) {
795 int local_max_level;
796 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
797 gc_cause() == GCCause::_gc_locker) {
798 local_max_level = 0;
799 } else {
800 local_max_level = max_level;
801 }
802
803 do_collection(true /* full */,
804 clear_all_soft_refs /* clear_all_soft_refs */,
805 0 /* size */,
806 false /* is_tlab */,
807 local_max_level /* max_level */);
808 // Hack XXX FIX ME !!!
809 // A scavenge may not have been attempted, or may have
810 // been attempted and failed, because the old gen was too full
811 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
812 incremental_collection_will_fail(false /* don't consult_young */)) {
813 if (PrintGCDetails) {
814 gclog_or_tty->print_cr("GC locker: Trying a full collection "
815 "because scavenge failed");
816 }
817 // This time allow the old gen to be collected as well
818 do_collection(true /* full */,
819 clear_all_soft_refs /* clear_all_soft_refs */,
820 0 /* size */,
821 false /* is_tlab */,
822 n_gens() - 1 /* max_level */);
823 }
824 }
825
826 bool GenCollectedHeap::is_in_young(oop p) {
827 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
828 assert(result == _young_gen->is_in_reserved(p),
829 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
830 return result;
831 }
832
833 // Returns "TRUE" iff "p" points into the committed areas of the heap.
834 bool GenCollectedHeap::is_in(const void* p) const {
835 #ifndef ASSERT
836 guarantee(VerifyBeforeGC ||
837 VerifyDuringGC ||
838 VerifyBeforeExit ||
839 VerifyDuringStartup ||
840 PrintAssembly ||
841 tty->count() != 0 || // already printing
842 VerifyAfterGC ||
843 VMError::fatal_error_in_progress(), "too expensive");
844
845 #endif
846 return _young_gen->is_in(p) || _old_gen->is_in(p);
847 }
848
849 #ifdef ASSERT
850 // Don't implement this by using is_in_young(). This method is used
851 // in some cases to check that is_in_young() is correct.
852 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
853 assert(is_in_reserved(p) || p == NULL,
854 "Does not work if address is non-null and outside of the heap");
855 return p < _young_gen->reserved().end() && p != NULL;
856 }
857 #endif
858
859 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
860 _young_gen->oop_iterate(cl);
861 _old_gen->oop_iterate(cl);
862 }
863
864 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
865 _young_gen->object_iterate(cl);
866 _old_gen->object_iterate(cl);
867 }
868
869 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
870 _young_gen->safe_object_iterate(cl);
871 _old_gen->safe_object_iterate(cl);
872 }
873
874 Space* GenCollectedHeap::space_containing(const void* addr) const {
875 Space* res = _young_gen->space_containing(addr);
876 if (res != NULL) {
877 return res;
878 }
879 res = _old_gen->space_containing(addr);
880 assert(res != NULL, "Could not find containing space");
881 return res;
882 }
883
884 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
885 assert(is_in_reserved(addr), "block_start of address outside of heap");
886 if (_young_gen->is_in_reserved(addr)) {
887 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
888 return _young_gen->block_start(addr);
889 }
890
891 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
892 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
893 return _old_gen->block_start(addr);
894 }
895
896 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
897 assert(is_in_reserved(addr), "block_size of address outside of heap");
898 if (_young_gen->is_in_reserved(addr)) {
899 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
900 return _young_gen->block_size(addr);
901 }
902
903 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
904 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
905 return _old_gen->block_size(addr);
906 }
907
908 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
909 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
910 assert(block_start(addr) == addr, "addr must be a block start");
911 if (_young_gen->is_in_reserved(addr)) {
912 return _young_gen->block_is_obj(addr);
913 }
914
915 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
916 return _old_gen->block_is_obj(addr);
917 }
918
919 bool GenCollectedHeap::supports_tlab_allocation() const {
920 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
921 return _young_gen->supports_tlab_allocation();
922 }
923
924 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
925 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
926 if (_young_gen->supports_tlab_allocation()) {
927 return _young_gen->tlab_capacity();
928 }
929 return 0;
930 }
931
932 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
933 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
934 if (_young_gen->supports_tlab_allocation()) {
935 return _young_gen->tlab_used();
936 }
937 return 0;
938 }
939
940 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
941 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
942 if (_young_gen->supports_tlab_allocation()) {
943 return _young_gen->unsafe_max_tlab_alloc();
944 }
945 return 0;
946 }
947
948 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
949 bool gc_overhead_limit_was_exceeded;
950 return collector_policy()->mem_allocate_work(size /* size */,
951 true /* is_tlab */,
952 &gc_overhead_limit_was_exceeded);
953 }
954
955 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
956 // from the list headed by "*prev_ptr".
957 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
958 bool first = true;
959 size_t min_size = 0; // "first" makes this conceptually infinite.
960 ScratchBlock **smallest_ptr, *smallest;
961 ScratchBlock *cur = *prev_ptr;
962 while (cur) {
963 assert(*prev_ptr == cur, "just checking");
964 if (first || cur->num_words < min_size) {
965 smallest_ptr = prev_ptr;
966 smallest = cur;
967 min_size = smallest->num_words;
968 first = false;
969 }
970 prev_ptr = &cur->next;
971 cur = cur->next;
972 }
973 smallest = *smallest_ptr;
974 *smallest_ptr = smallest->next;
975 return smallest;
976 }
977
978 // Sort the scratch block list headed by res into decreasing size order,
979 // and set "res" to the result.
980 static void sort_scratch_list(ScratchBlock*& list) {
981 ScratchBlock* sorted = NULL;
982 ScratchBlock* unsorted = list;
983 while (unsorted) {
984 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
985 smallest->next = sorted;
986 sorted = smallest;
987 }
988 list = sorted;
989 }
990
991 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
992 size_t max_alloc_words) {
993 ScratchBlock* res = NULL;
994 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
995 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
996 sort_scratch_list(res);
997 return res;
998 }
999
1000 void GenCollectedHeap::release_scratch() {
1001 _young_gen->reset_scratch();
1002 _old_gen->reset_scratch();
1003 }
1004
1005 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1006 void do_generation(Generation* gen) {
1007 gen->prepare_for_verify();
1008 }
1009 };
1010
1011 void GenCollectedHeap::prepare_for_verify() {
1012 ensure_parsability(false); // no need to retire TLABs
1013 GenPrepareForVerifyClosure blk;
1014 generation_iterate(&blk, false);
1015 }
1016
1017 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1018 bool old_to_young) {
1019 if (old_to_young) {
1020 cl->do_generation(_old_gen);
1021 cl->do_generation(_young_gen);
1022 } else {
1023 cl->do_generation(_young_gen);
1024 cl->do_generation(_old_gen);
1025 }
1026 }
1027
1028 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1029 _young_gen->space_iterate(cl, true);
1030 _old_gen->space_iterate(cl, true);
1031 }
1032
1033 bool GenCollectedHeap::is_maximal_no_gc() const {
1034 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1035 }
1036
1037 void GenCollectedHeap::save_marks() {
1038 _young_gen->save_marks();
1039 _old_gen->save_marks();
1040 }
1041
1042 GenCollectedHeap* GenCollectedHeap::heap() {
1043 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1044 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1045 return _gch;
1046 }
1047
1048
1049 void GenCollectedHeap::prepare_for_compaction() {
1050 guarantee(_n_gens = 2, "Wrong number of generations");
1051 // Start by compacting into same gen.
1052 CompactPoint cp(_old_gen);
1053 _old_gen->prepare_for_compaction(&cp);
1054 _young_gen->prepare_for_compaction(&cp);
1055 }
1056
1057 GCStats* GenCollectedHeap::gc_stats(int level) const {
1058 if (level == 0) {
1059 return _young_gen->gc_stats();
1060 } else {
1061 return _old_gen->gc_stats();
1062 }
1063 }
1064
1065 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1066 if (!silent) {
1067 gclog_or_tty->print("%s", _old_gen->name());
1068 gclog_or_tty->print(" ");
1069 }
1070 _old_gen->verify();
1071
1072 if (!silent) {
1073 gclog_or_tty->print("%s", _young_gen->name());
1074 gclog_or_tty->print(" ");
1075 }
1076 _young_gen->verify();
1077
1078 if (!silent) {
1079 gclog_or_tty->print("remset ");
1080 }
1081 rem_set()->verify();
1082 }
1083
1084 void GenCollectedHeap::print_on(outputStream* st) const {
1085 _young_gen->print_on(st);
1086 _old_gen->print_on(st);
1087 MetaspaceAux::print_on(st);
1088 }
1089
1090 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1091 if (workers() != NULL) {
1092 workers()->threads_do(tc);
1093 }
1094 #if INCLUDE_ALL_GCS
1095 if (UseConcMarkSweepGC) {
1096 ConcurrentMarkSweepThread::threads_do(tc);
1097 }
1098 #endif // INCLUDE_ALL_GCS
1099 }
1100
1101 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1102 #if INCLUDE_ALL_GCS
1103 if (UseConcMarkSweepGC) {
1104 workers()->print_worker_threads_on(st);
1105 ConcurrentMarkSweepThread::print_all_on(st);
1106 }
1107 #endif // INCLUDE_ALL_GCS
1108 }
1109
1110 void GenCollectedHeap::print_on_error(outputStream* st) const {
1111 this->CollectedHeap::print_on_error(st);
1112
1113 #if INCLUDE_ALL_GCS
1114 if (UseConcMarkSweepGC) {
1115 st->cr();
1116 CMSCollector::print_on_error(st);
1117 }
1118 #endif // INCLUDE_ALL_GCS
1119 }
1120
1121 void GenCollectedHeap::print_tracing_info() const {
1122 if (TraceYoungGenTime) {
1123 get_gen(0)->print_summary_info();
1124 }
1125 if (TraceOldGenTime) {
1126 get_gen(1)->print_summary_info();
1127 }
1128 }
1129
1130 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1131 if (PrintGCDetails && Verbose) {
1132 gclog_or_tty->print(" " SIZE_FORMAT
1133 "->" SIZE_FORMAT
1134 "(" SIZE_FORMAT ")",
1135 prev_used, used(), capacity());
1136 } else {
1137 gclog_or_tty->print(" " SIZE_FORMAT "K"
1138 "->" SIZE_FORMAT "K"
1139 "(" SIZE_FORMAT "K)",
1140 prev_used / K, used() / K, capacity() / K);
1141 }
1142 }
1143
1144 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1145 private:
1146 bool _full;
1147 public:
1148 void do_generation(Generation* gen) {
1149 gen->gc_prologue(_full);
1150 }
1151 GenGCPrologueClosure(bool full) : _full(full) {};
1152 };
1153
1154 void GenCollectedHeap::gc_prologue(bool full) {
1155 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1156
1157 always_do_update_barrier = false;
1158 // Fill TLAB's and such
1159 CollectedHeap::accumulate_statistics_all_tlabs();
1160 ensure_parsability(true); // retire TLABs
1161
1162 // Walk generations
1163 GenGCPrologueClosure blk(full);
1164 generation_iterate(&blk, false); // not old-to-young.
1165 };
1166
1167 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1168 private:
1169 bool _full;
1170 public:
1171 void do_generation(Generation* gen) {
1172 gen->gc_epilogue(_full);
1173 }
1174 GenGCEpilogueClosure(bool full) : _full(full) {};
1175 };
1176
1177 void GenCollectedHeap::gc_epilogue(bool full) {
1178 #ifdef COMPILER2
1179 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1180 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1181 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1182 #endif /* COMPILER2 */
1183
1184 resize_all_tlabs();
1185
1186 GenGCEpilogueClosure blk(full);
1187 generation_iterate(&blk, false); // not old-to-young.
1188
1189 if (!CleanChunkPoolAsync) {
1190 Chunk::clean_chunk_pool();
1191 }
1192
1193 MetaspaceCounters::update_performance_counters();
1194 CompressedClassSpaceCounters::update_performance_counters();
1195
1196 always_do_update_barrier = UseConcMarkSweepGC;
1197 };
1198
1199 #ifndef PRODUCT
1200 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1201 private:
1202 public:
1203 void do_generation(Generation* gen) {
1204 gen->record_spaces_top();
1205 }
1206 };
1207
1208 void GenCollectedHeap::record_gen_tops_before_GC() {
1209 if (ZapUnusedHeapArea) {
1210 GenGCSaveTopsBeforeGCClosure blk;
1211 generation_iterate(&blk, false); // not old-to-young.
1212 }
1213 }
1214 #endif // not PRODUCT
1215
1216 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1217 public:
1218 void do_generation(Generation* gen) {
1219 gen->ensure_parsability();
1220 }
1221 };
1222
1223 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1224 CollectedHeap::ensure_parsability(retire_tlabs);
1225 GenEnsureParsabilityClosure ep_cl;
1226 generation_iterate(&ep_cl, false);
1227 }
1228
1229 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1230 oop obj,
1231 size_t obj_size) {
1232 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1233 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1234 HeapWord* result = NULL;
1235
1236 result = old_gen->expand_and_allocate(obj_size, false);
1237
1238 if (result != NULL) {
1239 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1240 }
1241 return oop(result);
1242 }
1243
1244 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1245 jlong _time; // in ms
1246 jlong _now; // in ms
1247
1248 public:
1249 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1250
1251 jlong time() { return _time; }
1252
1253 void do_generation(Generation* gen) {
1254 _time = MIN2(_time, gen->time_of_last_gc(_now));
1255 }
1256 };
1257
1258 jlong GenCollectedHeap::millis_since_last_gc() {
1259 // We need a monotonically non-decreasing time in ms but
1260 // os::javaTimeMillis() does not guarantee monotonicity.
1261 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1262 GenTimeOfLastGCClosure tolgc_cl(now);
1263 // iterate over generations getting the oldest
1264 // time that a generation was collected
1265 generation_iterate(&tolgc_cl, false);
1266
1267 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1268 // provided the underlying platform provides such a time source
1269 // (and it is bug free). So we still have to guard against getting
1270 // back a time later than 'now'.
1271 jlong retVal = now - tolgc_cl.time();
1272 if (retVal < 0) {
1273 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1274 return 0;
1275 }
1276 return retVal;
1277 }