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.
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 "oops/oop.inline2.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/memoryService.hpp"
52 #include "utilities/vmError.hpp"
53 #include "utilities/workgroup.hpp"
54 #include "utilities/macros.hpp"
55 #if INCLUDE_ALL_GCS
56 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
57 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
58 #endif // INCLUDE_ALL_GCS
59
60 GenCollectedHeap* GenCollectedHeap::_gch;
61 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
62
63 // The set of potentially parallel tasks in root scanning.
64 enum GCH_strong_roots_tasks {
65 // We probably want to parallelize both of these internally, but for now...
66 GCH_PS_younger_gens,
67 // Leave this one last.
68 GCH_PS_NumElements
69 };
70
71 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
72 SharedHeap(policy),
73 _rem_set(NULL),
74 _gen_policy(policy),
75 _gen_process_roots_tasks(new SubTasksDone(GCH_PS_NumElements)),
76 _full_collections_completed(0)
77 {
78 if (_gen_process_roots_tasks == NULL ||
79 !_gen_process_roots_tasks->valid()) {
80 vm_exit_during_initialization("Failed necessary allocation.");
81 }
82 assert(policy != NULL, "Sanity check");
83 }
84
85 jint GenCollectedHeap::initialize() {
86 CollectedHeap::pre_initialize();
87
88 int i;
89 _n_gens = gen_policy()->number_of_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 size_t total_reserved = 0;
112 ReservedSpace heap_rs;
113
114 size_t heap_alignment = collector_policy()->heap_alignment();
115
116 heap_address = allocate(heap_alignment, &total_reserved, &heap_rs);
117
118 if (!heap_rs.is_reserved()) {
119 vm_shutdown_during_initialization(
120 "Could not reserve enough space for object heap");
121 return JNI_ENOMEM;
122 }
123
124 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
125
126 _rem_set = collector_policy()->create_rem_set(reserved_region());
127 set_barrier_set(rem_set()->bs());
128
129 _gch = this;
130
131 ReservedSpace young_rs = heap_rs.first_part(_gen_specs[0]->max_size(), false, false);
132 _young_gen = _gen_specs[0]->init(young_rs, 0, rem_set());
133 heap_rs = heap_rs.last_part(_gen_specs[0]->max_size());
134
135 ReservedSpace old_rs = heap_rs.first_part(_gen_specs[1]->max_size(), false, false);
136 _old_gen = _gen_specs[1]->init(old_rs, 1, rem_set());
137 heap_rs = heap_rs.last_part(_gen_specs[1]->max_size());
138 clear_incremental_collection_failed();
139
140 #if INCLUDE_ALL_GCS
141 // If we are running CMS, create the collector responsible
142 // for collecting the CMS generations.
143 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
144 bool success = create_cms_collector();
145 if (!success) return JNI_ENOMEM;
146 }
147 #endif // INCLUDE_ALL_GCS
148
149 return JNI_OK;
150 }
151
152 char* GenCollectedHeap::allocate(size_t alignment,
153 size_t* _total_reserved,
154 ReservedSpace* heap_rs){
155 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
156 "the maximum representable size";
157
158 // Now figure out the total size.
159 size_t total_reserved = 0;
160 const size_t pageSize = UseLargePages ?
161 os::large_page_size() : os::vm_page_size();
162
163 assert(alignment % pageSize == 0, "Must be");
164
165 for (int i = 0; i < _n_gens; i++) {
166 total_reserved += _gen_specs[i]->max_size();
167 if (total_reserved < _gen_specs[i]->max_size()) {
168 vm_exit_during_initialization(overflow_msg);
169 }
170 }
171 assert(total_reserved % alignment == 0,
172 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
173 SIZE_FORMAT, total_reserved, alignment));
174
175 *_total_reserved = total_reserved;
176
177 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
178 return heap_rs->base();
179 }
180
181 void GenCollectedHeap::post_initialize() {
182 SharedHeap::post_initialize();
183 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
184 guarantee(policy->is_generation_policy(), "Illegal policy type");
185 assert((get_gen(0)->kind() == Generation::DefNew) ||
186 (get_gen(0)->kind() == Generation::ParNew),
187 "Wrong youngest generation type");
188 DefNewGeneration* def_new_gen = (DefNewGeneration*)get_gen(0);
189
190 Generation* old_gen = get_gen(1);
191 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
192 old_gen->kind() == Generation::MarkSweepCompact,
193 "Wrong generation kind");
194
195 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
196 old_gen->capacity(),
197 def_new_gen->from()->capacity());
198 policy->initialize_gc_policy_counters();
199 }
200
201 void GenCollectedHeap::ref_processing_init() {
202 SharedHeap::ref_processing_init();
203 _young_gen->ref_processor_init();
204 _old_gen->ref_processor_init();
205 }
206
207 size_t GenCollectedHeap::capacity() const {
208 return _young_gen->capacity() + _old_gen->capacity();
209 }
210
211 size_t GenCollectedHeap::used() const {
212 return _young_gen->used() + _old_gen->used();
213 }
214
215 // Save the "used_region" for generations level and lower.
216 void GenCollectedHeap::save_used_regions(int level) {
217 assert(level < _n_gens, "Illegal level parameter");
218 if (level == 1) {
219 _old_gen->save_used_region();
220 }
221 _young_gen->save_used_region();
222 }
223
224 size_t GenCollectedHeap::max_capacity() const {
225 return _young_gen->max_capacity() + _old_gen->max_capacity();
226 }
227
228 // Update the _full_collections_completed counter
229 // at the end of a stop-world full GC.
230 unsigned int GenCollectedHeap::update_full_collections_completed() {
231 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
232 assert(_full_collections_completed <= _total_full_collections,
233 "Can't complete more collections than were started");
234 _full_collections_completed = _total_full_collections;
235 ml.notify_all();
236 return _full_collections_completed;
237 }
238
239 // Update the _full_collections_completed counter, as appropriate,
240 // at the end of a concurrent GC cycle. Note the conditional update
241 // below to allow this method to be called by a concurrent collector
242 // without synchronizing in any manner with the VM thread (which
243 // may already have initiated a STW full collection "concurrently").
244 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
245 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
246 assert((_full_collections_completed <= _total_full_collections) &&
247 (count <= _total_full_collections),
248 "Can't complete more collections than were started");
249 if (count > _full_collections_completed) {
250 _full_collections_completed = count;
251 ml.notify_all();
252 }
253 return _full_collections_completed;
254 }
255
256
257 #ifndef PRODUCT
258 // Override of memory state checking method in CollectedHeap:
259 // Some collectors (CMS for example) can't have badHeapWordVal written
260 // in the first two words of an object. (For instance , in the case of
261 // CMS these words hold state used to synchronize between certain
262 // (concurrent) GC steps and direct allocating mutators.)
263 // The skip_header_HeapWords() method below, allows us to skip
264 // over the requisite number of HeapWord's. Note that (for
265 // generational collectors) this means that those many words are
266 // skipped in each object, irrespective of the generation in which
267 // that object lives. The resultant loss of precision seems to be
268 // harmless and the pain of avoiding that imprecision appears somewhat
269 // higher than we are prepared to pay for such rudimentary debugging
270 // support.
271 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
272 size_t size) {
273 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
274 // We are asked to check a size in HeapWords,
275 // but the memory is mangled in juint words.
276 juint* start = (juint*) (addr + skip_header_HeapWords());
277 juint* end = (juint*) (addr + size);
278 for (juint* slot = start; slot < end; slot += 1) {
279 assert(*slot == badHeapWordVal,
280 "Found non badHeapWordValue in pre-allocation check");
281 }
282 }
283 }
284 #endif
285
286 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
287 bool is_tlab,
288 bool first_only) {
289 HeapWord* res = NULL;
290
291 if (_young_gen->should_allocate(size, is_tlab)) {
292 res = _young_gen->allocate(size, is_tlab);
293 if (res != NULL || first_only) {
294 return res;
295 }
296 }
297
298 if (_old_gen->should_allocate(size, is_tlab)) {
299 res = _old_gen->allocate(size, is_tlab);
300 }
301
302 return res;
303 }
304
305 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
306 bool* gc_overhead_limit_was_exceeded) {
307 return collector_policy()->mem_allocate_work(size,
308 false /* is_tlab */,
309 gc_overhead_limit_was_exceeded);
310 }
311
312 bool GenCollectedHeap::must_clear_all_soft_refs() {
313 return _gc_cause == GCCause::_last_ditch_collection;
314 }
315
316 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
317 return UseConcMarkSweepGC &&
318 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
319 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
320 }
321
322 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
323 bool is_tlab, bool run_verification, bool clear_soft_refs) {
324 // Timer for individual generations. Last argument is false: no CR
325 // FIXME: We should try to start the timing earlier to cover more of the GC pause
326 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
327 // so we can assume here that the next GC id is what we want.
328 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
329 TraceCollectorStats tcs(gen->counters());
330 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
331
332 size_t prev_used = gen->used();
333 gen->stat_record()->invocations++;
334 gen->stat_record()->accumulated_time.start();
335
336 // Must be done anew before each collection because
337 // a previous collection will do mangling and will
338 // change top of some spaces.
339 record_gen_tops_before_GC();
340
341 if (PrintGC && Verbose) {
342 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
343 gen->level(),
344 gen->stat_record()->invocations,
345 size * HeapWordSize);
346 }
347
348 if (run_verification && VerifyBeforeGC) {
349 HandleMark hm; // Discard invalid handles created during verification
350 Universe::verify(" VerifyBeforeGC:");
351 }
352 COMPILER2_PRESENT(DerivedPointerTable::clear());
353
354 // Do collection work
355 {
356 // Note on ref discovery: For what appear to be historical reasons,
357 // GCH enables and disabled (by enqueing) refs discovery.
358 // In the future this should be moved into the generation's
359 // collect method so that ref discovery and enqueueing concerns
360 // are local to a generation. The collect method could return
361 // an appropriate indication in the case that notification on
362 // the ref lock was needed. This will make the treatment of
363 // weak refs more uniform (and indeed remove such concerns
364 // from GCH). XXX
365
366 HandleMark hm; // Discard invalid handles created during gc
367 save_marks(); // save marks for all gens
368 // We want to discover references, but not process them yet.
369 // This mode is disabled in process_discovered_references if the
370 // generation does some collection work, or in
371 // enqueue_discovered_references if the generation returns
372 // without doing any work.
373 ReferenceProcessor* rp = gen->ref_processor();
374 // If the discovery of ("weak") refs in this generation is
375 // atomic wrt other collectors in this configuration, we
376 // are guaranteed to have empty discovered ref lists.
377 if (rp->discovery_is_atomic()) {
378 rp->enable_discovery();
379 rp->setup_policy(clear_soft_refs);
380 } else {
381 // collect() below will enable discovery as appropriate
382 }
383 gen->collect(full, clear_soft_refs, size, is_tlab);
384 if (!rp->enqueuing_is_done()) {
385 rp->enqueue_discovered_references();
386 } else {
387 rp->set_enqueuing_is_done(false);
388 }
389 rp->verify_no_references_recorded();
390 }
391
392 // Determine if allocation request was met.
393 if (size > 0) {
394 if (!is_tlab || gen->supports_tlab_allocation()) {
395 if (size * HeapWordSize <= gen->unsafe_max_alloc_nogc()) {
396 size = 0;
397 }
398 }
399 }
400
401 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
402
403 gen->stat_record()->accumulated_time.stop();
404
405 update_gc_stats(gen->level(), full);
406
407 if (run_verification && VerifyAfterGC) {
408 HandleMark hm; // Discard invalid handles created during verification
409 Universe::verify(" VerifyAfterGC:");
410 }
411
412 if (PrintGCDetails) {
413 gclog_or_tty->print(":");
414 gen->print_heap_change(prev_used);
415 }
416 }
417
418 void GenCollectedHeap::do_collection(bool full,
419 bool clear_all_soft_refs,
420 size_t size,
421 bool is_tlab,
422 int max_level) {
423 ResourceMark rm;
424 DEBUG_ONLY(Thread* my_thread = Thread::current();)
425
426 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
427 assert(my_thread->is_VM_thread() ||
428 my_thread->is_ConcurrentGC_thread(),
429 "incorrect thread type capability");
430 assert(Heap_lock->is_locked(),
431 "the requesting thread should have the Heap_lock");
432 guarantee(!is_gc_active(), "collection is not reentrant");
433 assert(max_level < n_gens(), "sanity check");
434
435 if (GC_locker::check_active_before_gc()) {
436 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
437 }
438
439 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
440 collector_policy()->should_clear_all_soft_refs();
441
442 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
443
444 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
445
446 print_heap_before_gc();
447
448 {
449 FlagSetting fl(_is_gc_active, true);
450
451 bool complete = full && (max_level == (n_gens()-1));
452 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
453 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
454 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
455 // so we can assume here that the next GC id is what we want.
456 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
457
458 gc_prologue(complete);
459 increment_total_collections(complete);
460
461 size_t gch_prev_used = used();
462 bool must_restore_marks_for_biased_locking = false;
463 bool run_verification = total_collections() >= VerifyGCStartAt;
464
465 if (_young_gen->performs_in_place_marking() ||
466 _old_gen->performs_in_place_marking()) {
467 // We want to avoid doing this for
468 // scavenge-only collections where it's unnecessary.
469 must_restore_marks_for_biased_locking = true;
470 BiasedLocking::preserve_marks();
471 }
472
473 bool prepared_for_verification = false;
474 int max_level_collected = 0;
475 if (!(full && _old_gen->full_collects_younger_generations()) &&
476 _young_gen->should_collect(full, size, is_tlab)) {
477 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
478 prepare_for_verify();
479 prepared_for_verification = true;
480 }
481 collect_generation(_young_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 0, do_clear_all_soft_refs);
482 }
483 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
484 if (!complete) {
485 // The full_collections increment was missed above.
486 increment_total_full_collections();
487 }
488 pre_full_gc_dump(NULL); // do any pre full gc dumps
489 if (run_verification && VerifyGCLevel <= 1 && VerifyBeforeGC) {
490 if (!prepared_for_verification) {
491 prepare_for_verify();
492 }
493 }
494 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs);
495 max_level_collected = 1;
496 }
497
498 // Update "complete" boolean wrt what actually transpired --
499 // for instance, a promotion failure could have led to
500 // a whole heap collection.
501 complete = complete || (max_level_collected == n_gens() - 1);
502
503 if (complete) { // We did a "major" collection
504 // FIXME: See comment at pre_full_gc_dump call
505 post_full_gc_dump(NULL); // do any post full gc dumps
506 }
507
508 if (PrintGCDetails) {
509 print_heap_change(gch_prev_used);
510
511 // Print metaspace info for full GC with PrintGCDetails flag.
512 if (complete) {
513 MetaspaceAux::print_metaspace_change(metadata_prev_used);
514 }
515 }
516
517 // Adjust generation sizes.
518 if (max_level_collected == 1) {
519 _old_gen->compute_new_size();
520 }
521 _young_gen->compute_new_size();
522
523 if (complete) {
524 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
525 ClassLoaderDataGraph::purge();
526 MetaspaceAux::verify_metrics();
527 // Resize the metaspace capacity after full collections
528 MetaspaceGC::compute_new_size();
529 update_full_collections_completed();
530 }
531
532 // Track memory usage and detect low memory after GC finishes
533 MemoryService::track_memory_usage();
534
535 gc_epilogue(complete);
536
537 if (must_restore_marks_for_biased_locking) {
538 BiasedLocking::restore_marks();
539 }
540 }
541
542 print_heap_after_gc();
543
544 #ifdef TRACESPINNING
545 ParallelTaskTerminator::print_termination_counts();
546 #endif
547 }
548
549 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
550 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
551 }
552
553 void GenCollectedHeap::set_par_threads(uint t) {
554 SharedHeap::set_par_threads(t);
555 _gen_process_roots_tasks->set_n_threads(t);
556 }
557
558 void GenCollectedHeap::
559 gen_process_roots(int level,
560 bool younger_gens_as_roots,
561 bool activate_scope,
562 SharedHeap::ScanningOption so,
563 OopsInGenClosure* not_older_gens,
564 OopsInGenClosure* weak_roots,
565 OopsInGenClosure* older_gens,
566 CLDClosure* cld_closure,
567 CLDClosure* weak_cld_closure,
568 CodeBlobClosure* code_closure) {
569
570 // General roots.
571 SharedHeap::process_roots(activate_scope, so,
572 not_older_gens, weak_roots,
573 cld_closure, weak_cld_closure,
574 code_closure);
575
576 if (younger_gens_as_roots) {
577 if (!_gen_process_roots_tasks->is_task_claimed(GCH_PS_younger_gens)) {
578 if (level == 1) {
579 not_older_gens->set_generation(_young_gen);
580 _young_gen->oop_iterate(not_older_gens);
581 }
582 not_older_gens->reset_generation();
583 }
584 }
585 // When collection is parallel, all threads get to cooperate to do
586 // older-gen scanning.
587 if (level == 0) {
588 older_gens->set_generation(_old_gen);
589 rem_set()->younger_refs_iterate(_old_gen, older_gens);
590 older_gens->reset_generation();
591 }
592
593 _gen_process_roots_tasks->all_tasks_completed();
594 }
595
596 void GenCollectedHeap::
597 gen_process_roots(int level,
598 bool younger_gens_as_roots,
599 bool activate_scope,
600 SharedHeap::ScanningOption so,
601 bool only_strong_roots,
602 OopsInGenClosure* not_older_gens,
603 OopsInGenClosure* older_gens,
604 CLDClosure* cld_closure) {
605
606 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
607
608 bool is_moving_collection = false;
609 if (level == 0 || is_adjust_phase) {
610 // young collections are always moving
611 is_moving_collection = true;
612 }
613
614 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
615 CodeBlobClosure* code_closure = &mark_code_closure;
616
617 gen_process_roots(level,
618 younger_gens_as_roots,
619 activate_scope, so,
620 not_older_gens, only_strong_roots ? NULL : not_older_gens,
621 older_gens,
622 cld_closure, only_strong_roots ? NULL : cld_closure,
623 code_closure);
624
625 }
626
627 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
628 SharedHeap::process_weak_roots(root_closure);
629 // "Local" "weak" refs
630 _young_gen->ref_processor()->weak_oops_do(root_closure);
631 _old_gen->ref_processor()->weak_oops_do(root_closure);
632 }
633
634 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
635 void GenCollectedHeap:: \
636 oop_since_save_marks_iterate(int level, \
637 OopClosureType* cur, \
638 OopClosureType* older) { \
639 if (level == 0) { \
640 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
641 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
642 } else { \
643 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
644 } \
645 }
646
647 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
648
649 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
650
651 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
652 if (level == 0) {
653 if (!_young_gen->no_allocs_since_save_marks()) return false;
654 }
655 if (!_old_gen->no_allocs_since_save_marks()) return false;
656 return true;
657 }
658
659 bool GenCollectedHeap::supports_inline_contig_alloc() const {
660 return _young_gen->supports_inline_contig_alloc();
661 }
662
663 HeapWord** GenCollectedHeap::top_addr() const {
664 return _young_gen->top_addr();
665 }
666
667 HeapWord** GenCollectedHeap::end_addr() const {
668 return _young_gen->end_addr();
669 }
670
671 // public collection interfaces
672
673 void GenCollectedHeap::collect(GCCause::Cause cause) {
674 if (should_do_concurrent_full_gc(cause)) {
675 #if INCLUDE_ALL_GCS
676 // mostly concurrent full collection
677 collect_mostly_concurrent(cause);
678 #else // INCLUDE_ALL_GCS
679 ShouldNotReachHere();
680 #endif // INCLUDE_ALL_GCS
681 } else if (cause == GCCause::_wb_young_gc) {
682 // minor collection for WhiteBox API
683 collect(cause, 0);
684 } else {
685 #ifdef ASSERT
686 if (cause == GCCause::_scavenge_alot) {
687 // minor collection only
688 collect(cause, 0);
689 } else {
690 // Stop-the-world full collection
691 collect(cause, n_gens() - 1);
692 }
693 #else
694 // Stop-the-world full collection
695 collect(cause, n_gens() - 1);
696 #endif
697 }
698 }
699
700 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
701 // The caller doesn't have the Heap_lock
702 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
703 MutexLocker ml(Heap_lock);
704 collect_locked(cause, max_level);
705 }
706
707 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
708 // The caller has the Heap_lock
709 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
710 collect_locked(cause, n_gens() - 1);
711 }
712
713 // this is the private collection interface
714 // The Heap_lock is expected to be held on entry.
715
716 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
717 // Read the GC count while holding the Heap_lock
718 unsigned int gc_count_before = total_collections();
719 unsigned int full_gc_count_before = total_full_collections();
720 {
721 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
722 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
723 cause, max_level);
724 VMThread::execute(&op);
725 }
726 }
727
728 #if INCLUDE_ALL_GCS
729 bool GenCollectedHeap::create_cms_collector() {
730
731 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
732 "Unexpected generation kinds");
733 // Skip two header words in the block content verification
734 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
735 CMSCollector* collector = new CMSCollector(
736 (ConcurrentMarkSweepGeneration*)_old_gen,
737 _rem_set->as_CardTableRS(),
738 (ConcurrentMarkSweepPolicy*) collector_policy());
739
740 if (collector == NULL || !collector->completed_initialization()) {
741 if (collector) {
742 delete collector; // Be nice in embedded situation
743 }
744 vm_shutdown_during_initialization("Could not create CMS collector");
745 return false;
746 }
747 return true; // success
748 }
749
750 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
751 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
752
753 MutexLocker ml(Heap_lock);
754 // Read the GC counts while holding the Heap_lock
755 unsigned int full_gc_count_before = total_full_collections();
756 unsigned int gc_count_before = total_collections();
757 {
758 MutexUnlocker mu(Heap_lock);
759 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
760 VMThread::execute(&op);
761 }
762 }
763 #endif // INCLUDE_ALL_GCS
764
765 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
766 do_full_collection(clear_all_soft_refs, _n_gens - 1);
767 }
768
769 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
770 int max_level) {
771 int local_max_level;
772 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
773 gc_cause() == GCCause::_gc_locker) {
774 local_max_level = 0;
775 } else {
776 local_max_level = max_level;
777 }
778
779 do_collection(true /* full */,
780 clear_all_soft_refs /* clear_all_soft_refs */,
781 0 /* size */,
782 false /* is_tlab */,
783 local_max_level /* max_level */);
784 // Hack XXX FIX ME !!!
785 // A scavenge may not have been attempted, or may have
786 // been attempted and failed, because the old gen was too full
787 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
788 incremental_collection_will_fail(false /* don't consult_young */)) {
789 if (PrintGCDetails) {
790 gclog_or_tty->print_cr("GC locker: Trying a full collection "
791 "because scavenge failed");
792 }
793 // This time allow the old gen to be collected as well
794 do_collection(true /* full */,
795 clear_all_soft_refs /* clear_all_soft_refs */,
796 0 /* size */,
797 false /* is_tlab */,
798 n_gens() - 1 /* max_level */);
799 }
800 }
801
802 bool GenCollectedHeap::is_in_young(oop p) {
803 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
804 assert(result == _young_gen->is_in_reserved(p),
805 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
806 return result;
807 }
808
809 // Returns "TRUE" iff "p" points into the committed areas of the heap.
810 bool GenCollectedHeap::is_in(const void* p) const {
811 #ifndef ASSERT
812 guarantee(VerifyBeforeGC ||
813 VerifyDuringGC ||
814 VerifyBeforeExit ||
815 VerifyDuringStartup ||
816 PrintAssembly ||
817 tty->count() != 0 || // already printing
818 VerifyAfterGC ||
819 VMError::fatal_error_in_progress(), "too expensive");
820
821 #endif
822 // This might be sped up with a cache of the last generation that
823 // answered yes.
824 if (_young_gen->is_in(p) || _old_gen->is_in(p)) {
825 return true;
826 }
827 // Otherwise...
828 return false;
829 }
830
831 #ifdef ASSERT
832 // Don't implement this by using is_in_young(). This method is used
833 // in some cases to check that is_in_young() is correct.
834 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
835 assert(is_in_reserved(p) || p == NULL,
836 "Does not work if address is non-null and outside of the heap");
837 return p < _young_gen->reserved().end() && p != NULL;
838 }
839 #endif
840
841 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
842 _young_gen->oop_iterate(cl);
843 _old_gen->oop_iterate(cl);
844 }
845
846 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
847 _young_gen->object_iterate(cl);
848 _old_gen->object_iterate(cl);
849 }
850
851 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
852 _young_gen->safe_object_iterate(cl);
853 _old_gen->safe_object_iterate(cl);
854 }
855
856 Space* GenCollectedHeap::space_containing(const void* addr) const {
857 Space* res = _young_gen->space_containing(addr);
858 if (res != NULL) {
859 return res;
860 }
861 res = _old_gen->space_containing(addr);
862 assert(res != NULL, "Could not find containing space");
863 return res;
864 }
865
866 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
867 assert(is_in_reserved(addr), "block_start of address outside of heap");
868 if (_young_gen->is_in_reserved(addr)) {
869 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
870 return _young_gen->block_start(addr);
871 }
872
873 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
874 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
875 return _old_gen->block_start(addr);
876 }
877
878 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
879 assert(is_in_reserved(addr), "block_size of address outside of heap");
880 if (_young_gen->is_in_reserved(addr)) {
881 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
882 return _young_gen->block_size(addr);
883 }
884
885 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
886 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
887 return _old_gen->block_size(addr);
888 }
889
890 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
891 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
892 assert(block_start(addr) == addr, "addr must be a block start");
893 if (_young_gen->is_in_reserved(addr)) {
894 return _young_gen->block_is_obj(addr);
895 }
896
897 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
898 return _old_gen->block_is_obj(addr);
899 }
900
901 bool GenCollectedHeap::supports_tlab_allocation() const {
902 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
903 return _young_gen->supports_tlab_allocation();
904 }
905
906 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
907 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
908 if (_young_gen->supports_tlab_allocation()) {
909 return _young_gen->tlab_capacity();
910 }
911 return 0;
912 }
913
914 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
915 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
916 if (_young_gen->supports_tlab_allocation()) {
917 return _young_gen->tlab_used();
918 }
919 return 0;
920 }
921
922 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
923 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
924 if (_young_gen->supports_tlab_allocation()) {
925 return _young_gen->unsafe_max_tlab_alloc();
926 }
927 return 0;
928 }
929
930 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
931 bool gc_overhead_limit_was_exceeded;
932 return collector_policy()->mem_allocate_work(size /* size */,
933 true /* is_tlab */,
934 &gc_overhead_limit_was_exceeded);
935 }
936
937 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
938 // from the list headed by "*prev_ptr".
939 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
940 bool first = true;
941 size_t min_size = 0; // "first" makes this conceptually infinite.
942 ScratchBlock **smallest_ptr, *smallest;
943 ScratchBlock *cur = *prev_ptr;
944 while (cur) {
945 assert(*prev_ptr == cur, "just checking");
946 if (first || cur->num_words < min_size) {
947 smallest_ptr = prev_ptr;
948 smallest = cur;
949 min_size = smallest->num_words;
950 first = false;
951 }
952 prev_ptr = &cur->next;
953 cur = cur->next;
954 }
955 smallest = *smallest_ptr;
956 *smallest_ptr = smallest->next;
957 return smallest;
958 }
959
960 // Sort the scratch block list headed by res into decreasing size order,
961 // and set "res" to the result.
962 static void sort_scratch_list(ScratchBlock*& list) {
963 ScratchBlock* sorted = NULL;
964 ScratchBlock* unsorted = list;
965 while (unsorted) {
966 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
967 smallest->next = sorted;
968 sorted = smallest;
969 }
970 list = sorted;
971 }
972
973 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
974 size_t max_alloc_words) {
975 ScratchBlock* res = NULL;
976 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
977 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
978 sort_scratch_list(res);
979 return res;
980 }
981
982 void GenCollectedHeap::release_scratch() {
983 _young_gen->reset_scratch();
984 _old_gen->reset_scratch();
985 }
986
987 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
988 void do_generation(Generation* gen) {
989 gen->prepare_for_verify();
990 }
991 };
992
993 void GenCollectedHeap::prepare_for_verify() {
994 ensure_parsability(false); // no need to retire TLABs
995 GenPrepareForVerifyClosure blk;
996 generation_iterate(&blk, false);
997 }
998
999 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1000 bool old_to_young) {
1001 if (old_to_young) {
1002 cl->do_generation(_old_gen);
1003 cl->do_generation(_young_gen);
1004 } else {
1005 cl->do_generation(_young_gen);
1006 cl->do_generation(_old_gen);
1007 }
1008 }
1009
1010 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1011 _young_gen->space_iterate(cl, true);
1012 _old_gen->space_iterate(cl, true);
1013 }
1014
1015 bool GenCollectedHeap::is_maximal_no_gc() const {
1016 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1017 }
1018
1019 void GenCollectedHeap::save_marks() {
1020 _young_gen->save_marks();
1021 _old_gen->save_marks();
1022 }
1023
1024 GenCollectedHeap* GenCollectedHeap::heap() {
1025 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1026 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1027 return _gch;
1028 }
1029
1030
1031 void GenCollectedHeap::prepare_for_compaction() {
1032 guarantee(_n_gens = 2, "Wrong number of generations");
1033 Generation* old_gen = _old_gen;
1034 // Start by compacting into same gen.
1035 CompactPoint cp(old_gen);
1036 old_gen->prepare_for_compaction(&cp);
1037 Generation* young_gen = _young_gen;
1038 young_gen->prepare_for_compaction(&cp);
1039 }
1040
1041 GCStats* GenCollectedHeap::gc_stats(int level) const {
1042 if (level == 0) {
1043 return _young_gen->gc_stats();
1044 } else {
1045 return _old_gen->gc_stats();
1046 }
1047 }
1048
1049 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1050 if (!silent) {
1051 gclog_or_tty->print("%s", _old_gen->name());
1052 gclog_or_tty->print(" ");
1053 }
1054 _old_gen->verify();
1055
1056 if (!silent) {
1057 gclog_or_tty->print("%s", _young_gen->name());
1058 gclog_or_tty->print(" ");
1059 }
1060 _young_gen->verify();
1061
1062 if (!silent) {
1063 gclog_or_tty->print("remset ");
1064 }
1065 rem_set()->verify();
1066 }
1067
1068 void GenCollectedHeap::print_on(outputStream* st) const {
1069 _young_gen->print_on(st);
1070 _old_gen->print_on(st);
1071 MetaspaceAux::print_on(st);
1072 }
1073
1074 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1075 if (workers() != NULL) {
1076 workers()->threads_do(tc);
1077 }
1078 #if INCLUDE_ALL_GCS
1079 if (UseConcMarkSweepGC) {
1080 ConcurrentMarkSweepThread::threads_do(tc);
1081 }
1082 #endif // INCLUDE_ALL_GCS
1083 }
1084
1085 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1086 #if INCLUDE_ALL_GCS
1087 if (UseConcMarkSweepGC) {
1088 workers()->print_worker_threads_on(st);
1089 ConcurrentMarkSweepThread::print_all_on(st);
1090 }
1091 #endif // INCLUDE_ALL_GCS
1092 }
1093
1094 void GenCollectedHeap::print_on_error(outputStream* st) const {
1095 this->CollectedHeap::print_on_error(st);
1096
1097 #if INCLUDE_ALL_GCS
1098 if (UseConcMarkSweepGC) {
1099 st->cr();
1100 CMSCollector::print_on_error(st);
1101 }
1102 #endif // INCLUDE_ALL_GCS
1103 }
1104
1105 void GenCollectedHeap::print_tracing_info() const {
1106 if (TraceYoungGenTime) {
1107 get_gen(0)->print_summary_info();
1108 }
1109 if (TraceOldGenTime) {
1110 get_gen(1)->print_summary_info();
1111 }
1112 }
1113
1114 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1115 if (PrintGCDetails && Verbose) {
1116 gclog_or_tty->print(" " SIZE_FORMAT
1117 "->" SIZE_FORMAT
1118 "(" SIZE_FORMAT ")",
1119 prev_used, used(), capacity());
1120 } else {
1121 gclog_or_tty->print(" " SIZE_FORMAT "K"
1122 "->" SIZE_FORMAT "K"
1123 "(" SIZE_FORMAT "K)",
1124 prev_used / K, used() / K, capacity() / K);
1125 }
1126 }
1127
1128 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1129 private:
1130 bool _full;
1131 public:
1132 void do_generation(Generation* gen) {
1133 gen->gc_prologue(_full);
1134 }
1135 GenGCPrologueClosure(bool full) : _full(full) {};
1136 };
1137
1138 void GenCollectedHeap::gc_prologue(bool full) {
1139 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1140
1141 always_do_update_barrier = false;
1142 // Fill TLAB's and such
1143 CollectedHeap::accumulate_statistics_all_tlabs();
1144 ensure_parsability(true); // retire TLABs
1145
1146 // Walk generations
1147 GenGCPrologueClosure blk(full);
1148 generation_iterate(&blk, false); // not old-to-young.
1149 };
1150
1151 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1152 private:
1153 bool _full;
1154 public:
1155 void do_generation(Generation* gen) {
1156 gen->gc_epilogue(_full);
1157 }
1158 GenGCEpilogueClosure(bool full) : _full(full) {};
1159 };
1160
1161 void GenCollectedHeap::gc_epilogue(bool full) {
1162 #ifdef COMPILER2
1163 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1164 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1165 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1166 #endif /* COMPILER2 */
1167
1168 resize_all_tlabs();
1169
1170 GenGCEpilogueClosure blk(full);
1171 generation_iterate(&blk, false); // not old-to-young.
1172
1173 if (!CleanChunkPoolAsync) {
1174 Chunk::clean_chunk_pool();
1175 }
1176
1177 MetaspaceCounters::update_performance_counters();
1178 CompressedClassSpaceCounters::update_performance_counters();
1179
1180 always_do_update_barrier = UseConcMarkSweepGC;
1181 };
1182
1183 #ifndef PRODUCT
1184 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1185 private:
1186 public:
1187 void do_generation(Generation* gen) {
1188 gen->record_spaces_top();
1189 }
1190 };
1191
1192 void GenCollectedHeap::record_gen_tops_before_GC() {
1193 if (ZapUnusedHeapArea) {
1194 GenGCSaveTopsBeforeGCClosure blk;
1195 generation_iterate(&blk, false); // not old-to-young.
1196 }
1197 }
1198 #endif // not PRODUCT
1199
1200 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1201 public:
1202 void do_generation(Generation* gen) {
1203 gen->ensure_parsability();
1204 }
1205 };
1206
1207 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1208 CollectedHeap::ensure_parsability(retire_tlabs);
1209 GenEnsureParsabilityClosure ep_cl;
1210 generation_iterate(&ep_cl, false);
1211 }
1212
1213 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1214 oop obj,
1215 size_t obj_size) {
1216 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1217 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1218 HeapWord* result = NULL;
1219
1220 result = old_gen->expand_and_allocate(obj_size, false);
1221
1222 if (result != NULL) {
1223 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1224 }
1225 return oop(result);
1226 }
1227
1228 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1229 jlong _time; // in ms
1230 jlong _now; // in ms
1231
1232 public:
1233 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1234
1235 jlong time() { return _time; }
1236
1237 void do_generation(Generation* gen) {
1238 _time = MIN2(_time, gen->time_of_last_gc(_now));
1239 }
1240 };
1241
1242 jlong GenCollectedHeap::millis_since_last_gc() {
1243 // We need a monotonically non-decreasing time in ms but
1244 // os::javaTimeMillis() does not guarantee monotonicity.
1245 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1246 GenTimeOfLastGCClosure tolgc_cl(now);
1247 // iterate over generations getting the oldest
1248 // time that a generation was collected
1249 generation_iterate(&tolgc_cl, false);
1250
1251 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1252 // provided the underlying platform provides such a time source
1253 // (and it is bug free). So we still have to guard against getting
1254 // back a time later than 'now'.
1255 jlong retVal = now - tolgc_cl.time();
1256 if (retVal < 0) {
1257 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1258 return 0;
1259 }
1260 return retVal;
1261 }