1 /*
2 * Copyright (c) 2000, 2013, 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/gcTraceTime.hpp"
32 #include "gc_implementation/shared/vmGCOperations.hpp"
33 #include "gc_interface/collectedHeap.inline.hpp"
34 #include "memory/filemap.hpp"
35 #include "memory/gcLocker.inline.hpp"
36 #include "memory/genCollectedHeap.hpp"
37 #include "memory/genOopClosures.inline.hpp"
38 #include "memory/generation.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 strong root scanning.
64 enum GCH_process_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 _gen_policy(policy),
74 _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
75 _full_collections_completed(0)
76 {
77 if (_gen_process_strong_tasks == NULL ||
78 !_gen_process_strong_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
90 // While there are no constraints in the GC code that HeapWordSize
91 // be any particular value, there are multiple other areas in the
92 // system which believe this to be true (e.g. oop->object_size in some
93 // cases incorrectly returns the size in wordSize units rather than
94 // HeapWordSize).
95 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
96
97 // The heap must be at least as aligned as generations.
98 size_t gen_alignment = Generation::GenGrain;
99
100 _gen_specs = gen_policy()->generations();
101
102 // Make sure the sizes are all aligned.
103 for (i = 0; i < _n_gens; i++) {
104 _gen_specs[i]->align(gen_alignment);
105 }
106
107 // Allocate space for the heap.
108
109 char* heap_address;
110 size_t total_reserved = 0;
111 int n_covered_regions = 0;
112 ReservedSpace heap_rs;
113
114 size_t heap_alignment = collector_policy()->heap_alignment();
115
116 heap_address = allocate(heap_alignment, &total_reserved,
117 &n_covered_regions, &heap_rs);
118
119 if (!heap_rs.is_reserved()) {
120 vm_shutdown_during_initialization(
121 "Could not reserve enough space for object heap");
122 return JNI_ENOMEM;
123 }
124
125 _reserved = MemRegion((HeapWord*)heap_rs.base(),
126 (HeapWord*)(heap_rs.base() + heap_rs.size()));
127
128 // It is important to do this in a way such that concurrent readers can't
129 // temporarily think something is in the heap. (Seen this happen in asserts.)
130 _reserved.set_word_size(0);
131 _reserved.set_start((HeapWord*)heap_rs.base());
132 size_t actual_heap_size = heap_rs.size();
133 _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
134
135 _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
136 set_barrier_set(rem_set()->bs());
137
138 _gch = this;
139
140 for (i = 0; i < _n_gens; i++) {
141 ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
142 _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
143 heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
144 }
145 clear_incremental_collection_failed();
146
147 #if INCLUDE_ALL_GCS
148 // If we are running CMS, create the collector responsible
149 // for collecting the CMS generations.
150 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
151 bool success = create_cms_collector();
152 if (!success) return JNI_ENOMEM;
153 }
154 #endif // INCLUDE_ALL_GCS
155
156 return JNI_OK;
157 }
158
159
160 char* GenCollectedHeap::allocate(size_t alignment,
161 size_t* _total_reserved,
162 int* _n_covered_regions,
163 ReservedSpace* heap_rs){
164 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
165 "the maximum representable size";
166
167 // Now figure out the total size.
168 size_t total_reserved = 0;
169 int n_covered_regions = 0;
170 const size_t pageSize = UseLargePages ?
171 os::large_page_size() : os::vm_page_size();
172
173 assert(alignment % pageSize == 0, "Must be");
174
175 for (int i = 0; i < _n_gens; i++) {
176 total_reserved += _gen_specs[i]->max_size();
177 if (total_reserved < _gen_specs[i]->max_size()) {
178 vm_exit_during_initialization(overflow_msg);
179 }
180 n_covered_regions += _gen_specs[i]->n_covered_regions();
181 }
182 assert(total_reserved % alignment == 0,
183 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
184 SIZE_FORMAT, total_reserved, alignment));
185
186 // Needed until the cardtable is fixed to have the right number
187 // of covered regions.
188 n_covered_regions += 2;
189
190 *_total_reserved = total_reserved;
191 *_n_covered_regions = n_covered_regions;
192
193 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
194 return heap_rs->base();
195 }
196
197
198 void GenCollectedHeap::post_initialize() {
199 SharedHeap::post_initialize();
200 TwoGenerationCollectorPolicy *policy =
201 (TwoGenerationCollectorPolicy *)collector_policy();
202 guarantee(policy->is_two_generation_policy(), "Illegal policy type");
203 DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
204 assert(def_new_gen->kind() == Generation::DefNew ||
205 def_new_gen->kind() == Generation::ParNew ||
206 def_new_gen->kind() == Generation::ASParNew,
207 "Wrong generation kind");
208
209 Generation* old_gen = get_gen(1);
210 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
211 old_gen->kind() == Generation::ASConcurrentMarkSweep ||
212 old_gen->kind() == Generation::MarkSweepCompact,
213 "Wrong generation kind");
214
215 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
216 old_gen->capacity(),
217 def_new_gen->from()->capacity());
218 policy->initialize_gc_policy_counters();
219 }
220
221 void GenCollectedHeap::ref_processing_init() {
222 SharedHeap::ref_processing_init();
223 for (int i = 0; i < _n_gens; i++) {
224 _gens[i]->ref_processor_init();
225 }
226 }
227
228 size_t GenCollectedHeap::capacity() const {
229 size_t res = 0;
230 for (int i = 0; i < _n_gens; i++) {
231 res += _gens[i]->capacity();
232 }
233 return res;
234 }
235
236 size_t GenCollectedHeap::used() const {
237 size_t res = 0;
238 for (int i = 0; i < _n_gens; i++) {
239 res += _gens[i]->used();
240 }
241 return res;
242 }
243
244 // Save the "used_region" for generations level and lower.
245 void GenCollectedHeap::save_used_regions(int level) {
246 assert(level < _n_gens, "Illegal level parameter");
247 for (int i = level; i >= 0; i--) {
248 _gens[i]->save_used_region();
249 }
250 }
251
252 size_t GenCollectedHeap::max_capacity() const {
253 size_t res = 0;
254 for (int i = 0; i < _n_gens; i++) {
255 res += _gens[i]->max_capacity();
256 }
257 return res;
258 }
259
260 // Update the _full_collections_completed counter
261 // at the end of a stop-world full GC.
262 unsigned int GenCollectedHeap::update_full_collections_completed() {
263 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
264 assert(_full_collections_completed <= _total_full_collections,
265 "Can't complete more collections than were started");
266 _full_collections_completed = _total_full_collections;
267 ml.notify_all();
268 return _full_collections_completed;
269 }
270
271 // Update the _full_collections_completed counter, as appropriate,
272 // at the end of a concurrent GC cycle. Note the conditional update
273 // below to allow this method to be called by a concurrent collector
274 // without synchronizing in any manner with the VM thread (which
275 // may already have initiated a STW full collection "concurrently").
276 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
277 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
278 assert((_full_collections_completed <= _total_full_collections) &&
279 (count <= _total_full_collections),
280 "Can't complete more collections than were started");
281 if (count > _full_collections_completed) {
282 _full_collections_completed = count;
283 ml.notify_all();
284 }
285 return _full_collections_completed;
286 }
287
288
289 #ifndef PRODUCT
290 // Override of memory state checking method in CollectedHeap:
291 // Some collectors (CMS for example) can't have badHeapWordVal written
292 // in the first two words of an object. (For instance , in the case of
293 // CMS these words hold state used to synchronize between certain
294 // (concurrent) GC steps and direct allocating mutators.)
295 // The skip_header_HeapWords() method below, allows us to skip
296 // over the requisite number of HeapWord's. Note that (for
297 // generational collectors) this means that those many words are
298 // skipped in each object, irrespective of the generation in which
299 // that object lives. The resultant loss of precision seems to be
300 // harmless and the pain of avoiding that imprecision appears somewhat
301 // higher than we are prepared to pay for such rudimentary debugging
302 // support.
303 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
304 size_t size) {
305 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
306 // We are asked to check a size in HeapWords,
307 // but the memory is mangled in juint words.
308 juint* start = (juint*) (addr + skip_header_HeapWords());
309 juint* end = (juint*) (addr + size);
310 for (juint* slot = start; slot < end; slot += 1) {
311 assert(*slot == badHeapWordVal,
312 "Found non badHeapWordValue in pre-allocation check");
313 }
314 }
315 }
316 #endif
317
318 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
319 bool is_tlab,
320 bool first_only) {
321 HeapWord* res;
322 for (int i = 0; i < _n_gens; i++) {
323 if (_gens[i]->should_allocate(size, is_tlab)) {
324 res = _gens[i]->allocate(size, is_tlab);
325 if (res != NULL) return res;
326 else if (first_only) break;
327 }
328 }
329 // Otherwise...
330 return NULL;
331 }
332
333 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
334 bool* gc_overhead_limit_was_exceeded) {
335 return collector_policy()->mem_allocate_work(size,
336 false /* is_tlab */,
337 gc_overhead_limit_was_exceeded);
338 }
339
340 bool GenCollectedHeap::must_clear_all_soft_refs() {
341 return _gc_cause == GCCause::_last_ditch_collection;
342 }
343
344 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
345 return UseConcMarkSweepGC &&
346 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
347 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
348 }
349
350 void GenCollectedHeap::do_collection(bool full,
351 bool clear_all_soft_refs,
352 size_t size,
353 bool is_tlab,
354 int max_level) {
355 bool prepared_for_verification = false;
356 ResourceMark rm;
357 DEBUG_ONLY(Thread* my_thread = Thread::current();)
358
359 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
360 assert(my_thread->is_VM_thread() ||
361 my_thread->is_ConcurrentGC_thread(),
362 "incorrect thread type capability");
363 assert(Heap_lock->is_locked(),
364 "the requesting thread should have the Heap_lock");
365 guarantee(!is_gc_active(), "collection is not reentrant");
366 assert(max_level < n_gens(), "sanity check");
367
368 if (GC_locker::check_active_before_gc()) {
369 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
370 }
371
372 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
373 collector_policy()->should_clear_all_soft_refs();
374
375 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
376
377 const size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
378
379 print_heap_before_gc();
380
381 {
382 FlagSetting fl(_is_gc_active, true);
383
384 bool complete = full && (max_level == (n_gens()-1));
385 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
386 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
387 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
388 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL);
389
390 gc_prologue(complete);
391 increment_total_collections(complete);
392
393 size_t gch_prev_used = used();
394
395 int starting_level = 0;
396 if (full) {
397 // Search for the oldest generation which will collect all younger
398 // generations, and start collection loop there.
399 for (int i = max_level; i >= 0; i--) {
400 if (_gens[i]->full_collects_younger_generations()) {
401 starting_level = i;
402 break;
403 }
404 }
405 }
406
407 bool must_restore_marks_for_biased_locking = false;
408
409 int max_level_collected = starting_level;
410 for (int i = starting_level; i <= max_level; i++) {
411 if (_gens[i]->should_collect(full, size, is_tlab)) {
412 if (i == n_gens() - 1) { // a major collection is to happen
413 if (!complete) {
414 // The full_collections increment was missed above.
415 increment_total_full_collections();
416 }
417 pre_full_gc_dump(NULL); // do any pre full gc dumps
418 }
419 // Timer for individual generations. Last argument is false: no CR
420 // FIXME: We should try to start the timing earlier to cover more of the GC pause
421 GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL);
422 TraceCollectorStats tcs(_gens[i]->counters());
423 TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
424
425 size_t prev_used = _gens[i]->used();
426 _gens[i]->stat_record()->invocations++;
427 _gens[i]->stat_record()->accumulated_time.start();
428
429 // Must be done anew before each collection because
430 // a previous collection will do mangling and will
431 // change top of some spaces.
432 record_gen_tops_before_GC();
433
434 if (PrintGC && Verbose) {
435 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
436 i,
437 _gens[i]->stat_record()->invocations,
438 size*HeapWordSize);
439 }
440
441 if (VerifyBeforeGC && i >= VerifyGCLevel &&
442 total_collections() >= VerifyGCStartAt) {
443 HandleMark hm; // Discard invalid handles created during verification
444 if (!prepared_for_verification) {
445 prepare_for_verify();
446 prepared_for_verification = true;
447 }
448 Universe::verify(" VerifyBeforeGC:");
449 }
450 COMPILER2_PRESENT(DerivedPointerTable::clear());
451
452 if (!must_restore_marks_for_biased_locking &&
453 _gens[i]->performs_in_place_marking()) {
454 // We perform this mark word preservation work lazily
455 // because it's only at this point that we know whether we
456 // absolutely have to do it; we want to avoid doing it for
457 // scavenge-only collections where it's unnecessary
458 must_restore_marks_for_biased_locking = true;
459 BiasedLocking::preserve_marks();
460 }
461
462 // Do collection work
463 {
464 // Note on ref discovery: For what appear to be historical reasons,
465 // GCH enables and disabled (by enqueing) refs discovery.
466 // In the future this should be moved into the generation's
467 // collect method so that ref discovery and enqueueing concerns
468 // are local to a generation. The collect method could return
469 // an appropriate indication in the case that notification on
470 // the ref lock was needed. This will make the treatment of
471 // weak refs more uniform (and indeed remove such concerns
472 // from GCH). XXX
473
474 HandleMark hm; // Discard invalid handles created during gc
475 save_marks(); // save marks for all gens
476 // We want to discover references, but not process them yet.
477 // This mode is disabled in process_discovered_references if the
478 // generation does some collection work, or in
479 // enqueue_discovered_references if the generation returns
480 // without doing any work.
481 ReferenceProcessor* rp = _gens[i]->ref_processor();
482 // If the discovery of ("weak") refs in this generation is
483 // atomic wrt other collectors in this configuration, we
484 // are guaranteed to have empty discovered ref lists.
485 if (rp->discovery_is_atomic()) {
486 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
487 rp->setup_policy(do_clear_all_soft_refs);
488 } else {
489 // collect() below will enable discovery as appropriate
490 }
491 _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
492 if (!rp->enqueuing_is_done()) {
493 rp->enqueue_discovered_references();
494 } else {
495 rp->set_enqueuing_is_done(false);
496 }
497 rp->verify_no_references_recorded();
498 }
499 max_level_collected = i;
500
501 // Determine if allocation request was met.
502 if (size > 0) {
503 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
504 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
505 size = 0;
506 }
507 }
508 }
509
510 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
511
512 _gens[i]->stat_record()->accumulated_time.stop();
513
514 update_gc_stats(i, full);
515
516 if (VerifyAfterGC && i >= VerifyGCLevel &&
517 total_collections() >= VerifyGCStartAt) {
518 HandleMark hm; // Discard invalid handles created during verification
519 Universe::verify(" VerifyAfterGC:");
520 }
521
522 if (PrintGCDetails) {
523 gclog_or_tty->print(":");
524 _gens[i]->print_heap_change(prev_used);
525 }
526 }
527 }
528
529 // Update "complete" boolean wrt what actually transpired --
530 // for instance, a promotion failure could have led to
531 // a whole heap collection.
532 complete = complete || (max_level_collected == n_gens() - 1);
533
534 if (complete) { // We did a "major" collection
535 // FIXME: See comment at pre_full_gc_dump call
536 post_full_gc_dump(NULL); // do any post full gc dumps
537 }
538
539 if (PrintGCDetails) {
540 print_heap_change(gch_prev_used);
541
542 // Print metaspace info for full GC with PrintGCDetails flag.
543 if (complete) {
544 MetaspaceAux::print_metaspace_change(metadata_prev_used);
545 }
546 }
547
548 for (int j = max_level_collected; j >= 0; j -= 1) {
549 // Adjust generation sizes.
550 _gens[j]->compute_new_size();
551 }
552
553 if (complete) {
554 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
555 ClassLoaderDataGraph::purge();
556 MetaspaceAux::verify_metrics();
557 // Resize the metaspace capacity after full collections
558 MetaspaceGC::compute_new_size();
559 update_full_collections_completed();
560 }
561
562 // Track memory usage and detect low memory after GC finishes
563 MemoryService::track_memory_usage();
564
565 gc_epilogue(complete);
566
567 if (must_restore_marks_for_biased_locking) {
568 BiasedLocking::restore_marks();
569 }
570 }
571
572 AdaptiveSizePolicy* sp = gen_policy()->size_policy();
573 AdaptiveSizePolicyOutput(sp, total_collections());
574
575 print_heap_after_gc();
576
577 #ifdef TRACESPINNING
578 ParallelTaskTerminator::print_termination_counts();
579 #endif
580 }
581
582 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
583 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
584 }
585
586 void GenCollectedHeap::set_par_threads(uint t) {
587 SharedHeap::set_par_threads(t);
588 _gen_process_strong_tasks->set_n_threads(t);
589 }
590
591 void GenCollectedHeap::
592 gen_process_strong_roots(int level,
593 bool younger_gens_as_roots,
594 bool activate_scope,
595 bool is_scavenging,
596 SharedHeap::ScanningOption so,
597 OopsInGenClosure* not_older_gens,
598 bool do_code_roots,
599 OopsInGenClosure* older_gens,
600 KlassClosure* klass_closure) {
601 // General strong roots.
602
603 if (!do_code_roots) {
604 SharedHeap::process_strong_roots(activate_scope, is_scavenging, so,
605 not_older_gens, NULL, klass_closure);
606 } else {
607 bool do_code_marking = (activate_scope || nmethod::oops_do_marking_is_active());
608 CodeBlobToOopClosure code_roots(not_older_gens, /*do_marking=*/ do_code_marking);
609 SharedHeap::process_strong_roots(activate_scope, is_scavenging, so,
610 not_older_gens, &code_roots, klass_closure);
611 }
612
613 if (younger_gens_as_roots) {
614 if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
615 for (int i = 0; i < level; i++) {
616 not_older_gens->set_generation(_gens[i]);
617 _gens[i]->oop_iterate(not_older_gens);
618 }
619 not_older_gens->reset_generation();
620 }
621 }
622 // When collection is parallel, all threads get to cooperate to do
623 // older-gen scanning.
624 for (int i = level+1; i < _n_gens; i++) {
625 older_gens->set_generation(_gens[i]);
626 rem_set()->younger_refs_iterate(_gens[i], older_gens);
627 older_gens->reset_generation();
628 }
629
630 _gen_process_strong_tasks->all_tasks_completed();
631 }
632
633 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
634 CodeBlobClosure* code_roots) {
635 SharedHeap::process_weak_roots(root_closure, code_roots);
636 // "Local" "weak" refs
637 for (int i = 0; i < _n_gens; i++) {
638 _gens[i]->ref_processor()->weak_oops_do(root_closure);
639 }
640 }
641
642 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
643 void GenCollectedHeap:: \
644 oop_since_save_marks_iterate(int level, \
645 OopClosureType* cur, \
646 OopClosureType* older) { \
647 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
648 for (int i = level+1; i < n_gens(); i++) { \
649 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
650 } \
651 }
652
653 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
654
655 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
656
657 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
658 for (int i = level; i < _n_gens; i++) {
659 if (!_gens[i]->no_allocs_since_save_marks()) return false;
660 }
661 return true;
662 }
663
664 bool GenCollectedHeap::supports_inline_contig_alloc() const {
665 return _gens[0]->supports_inline_contig_alloc();
666 }
667
668 HeapWord** GenCollectedHeap::top_addr() const {
669 return _gens[0]->top_addr();
670 }
671
672 HeapWord** GenCollectedHeap::end_addr() const {
673 return _gens[0]->end_addr();
674 }
675
676 // public collection interfaces
677
678 void GenCollectedHeap::collect(GCCause::Cause cause) {
679 if (should_do_concurrent_full_gc(cause)) {
680 #if INCLUDE_ALL_GCS
681 // mostly concurrent full collection
682 collect_mostly_concurrent(cause);
683 #else // INCLUDE_ALL_GCS
684 ShouldNotReachHere();
685 #endif // INCLUDE_ALL_GCS
686 } else {
687 #ifdef ASSERT
688 if (cause == GCCause::_scavenge_alot) {
689 // minor collection only
690 collect(cause, 0);
691 } else {
692 // Stop-the-world full collection
693 collect(cause, n_gens() - 1);
694 }
695 #else
696 // Stop-the-world full collection
697 collect(cause, n_gens() - 1);
698 #endif
699 }
700 }
701
702 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
703 // The caller doesn't have the Heap_lock
704 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
705 MutexLocker ml(Heap_lock);
706 collect_locked(cause, max_level);
707 }
708
709 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
710 // The caller has the Heap_lock
711 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
712 collect_locked(cause, n_gens() - 1);
713 }
714
715 // this is the private collection interface
716 // The Heap_lock is expected to be held on entry.
717
718 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
719 // Read the GC count while holding the Heap_lock
720 unsigned int gc_count_before = total_collections();
721 unsigned int full_gc_count_before = total_full_collections();
722 {
723 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
724 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
725 cause, max_level);
726 VMThread::execute(&op);
727 }
728 }
729
730 #if INCLUDE_ALL_GCS
731 bool GenCollectedHeap::create_cms_collector() {
732
733 assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
734 (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)),
735 "Unexpected generation kinds");
736 // Skip two header words in the block content verification
737 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
738 CMSCollector* collector = new CMSCollector(
739 (ConcurrentMarkSweepGeneration*)_gens[1],
740 _rem_set->as_CardTableRS(),
741 (ConcurrentMarkSweepPolicy*) collector_policy());
742
743 if (collector == NULL || !collector->completed_initialization()) {
744 if (collector) {
745 delete collector; // Be nice in embedded situation
746 }
747 vm_shutdown_during_initialization("Could not create CMS collector");
748 return false;
749 }
750 return true; // success
751 }
752
753 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
754 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
755
756 MutexLocker ml(Heap_lock);
757 // Read the GC counts while holding the Heap_lock
758 unsigned int full_gc_count_before = total_full_collections();
759 unsigned int gc_count_before = total_collections();
760 {
761 MutexUnlocker mu(Heap_lock);
762 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
763 VMThread::execute(&op);
764 }
765 }
766 #endif // INCLUDE_ALL_GCS
767
768 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
769 do_full_collection(clear_all_soft_refs, _n_gens - 1);
770 }
771
772 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
773 int max_level) {
774 int local_max_level;
775 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
776 gc_cause() == GCCause::_gc_locker) {
777 local_max_level = 0;
778 } else {
779 local_max_level = max_level;
780 }
781
782 do_collection(true /* full */,
783 clear_all_soft_refs /* clear_all_soft_refs */,
784 0 /* size */,
785 false /* is_tlab */,
786 local_max_level /* max_level */);
787 // Hack XXX FIX ME !!!
788 // A scavenge may not have been attempted, or may have
789 // been attempted and failed, because the old gen was too full
790 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
791 incremental_collection_will_fail(false /* don't consult_young */)) {
792 if (PrintGCDetails) {
793 gclog_or_tty->print_cr("GC locker: Trying a full collection "
794 "because scavenge failed");
795 }
796 // This time allow the old gen to be collected as well
797 do_collection(true /* full */,
798 clear_all_soft_refs /* clear_all_soft_refs */,
799 0 /* size */,
800 false /* is_tlab */,
801 n_gens() - 1 /* max_level */);
802 }
803 }
804
805 bool GenCollectedHeap::is_in_young(oop p) {
806 bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
807 assert(result == _gens[0]->is_in_reserved(p),
808 err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, (void*)p));
809 return result;
810 }
811
812 // Returns "TRUE" iff "p" points into the committed areas of the heap.
813 bool GenCollectedHeap::is_in(const void* p) const {
814 #ifndef ASSERT
815 guarantee(VerifyBeforeGC ||
816 VerifyDuringGC ||
817 VerifyBeforeExit ||
818 VerifyDuringStartup ||
819 PrintAssembly ||
820 tty->count() != 0 || // already printing
821 VerifyAfterGC ||
822 VMError::fatal_error_in_progress(), "too expensive");
823
824 #endif
825 // This might be sped up with a cache of the last generation that
826 // answered yes.
827 for (int i = 0; i < _n_gens; i++) {
828 if (_gens[i]->is_in(p)) return true;
829 }
830 // Otherwise...
831 return false;
832 }
833
834 #ifdef ASSERT
835 // Don't implement this by using is_in_young(). This method is used
836 // in some cases to check that is_in_young() is correct.
837 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
838 assert(is_in_reserved(p) || p == NULL,
839 "Does not work if address is non-null and outside of the heap");
840 return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
841 }
842 #endif
843
844 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
845 for (int i = 0; i < _n_gens; i++) {
846 _gens[i]->oop_iterate(cl);
847 }
848 }
849
850 void GenCollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
851 for (int i = 0; i < _n_gens; i++) {
852 _gens[i]->oop_iterate(mr, cl);
853 }
854 }
855
856 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
857 for (int i = 0; i < _n_gens; i++) {
858 _gens[i]->object_iterate(cl);
859 }
860 }
861
862 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
863 for (int i = 0; i < _n_gens; i++) {
864 _gens[i]->safe_object_iterate(cl);
865 }
866 }
867
868 Space* GenCollectedHeap::space_containing(const void* addr) const {
869 for (int i = 0; i < _n_gens; i++) {
870 Space* res = _gens[i]->space_containing(addr);
871 if (res != NULL) return res;
872 }
873 // Otherwise...
874 assert(false, "Could not find containing space");
875 return NULL;
876 }
877
878
879 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
880 assert(is_in_reserved(addr), "block_start of address outside of heap");
881 for (int i = 0; i < _n_gens; i++) {
882 if (_gens[i]->is_in_reserved(addr)) {
883 assert(_gens[i]->is_in(addr),
884 "addr should be in allocated part of generation");
885 return _gens[i]->block_start(addr);
886 }
887 }
888 assert(false, "Some generation should contain the address");
889 return NULL;
890 }
891
892 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
893 assert(is_in_reserved(addr), "block_size of address outside of heap");
894 for (int i = 0; i < _n_gens; i++) {
895 if (_gens[i]->is_in_reserved(addr)) {
896 assert(_gens[i]->is_in(addr),
897 "addr should be in allocated part of generation");
898 return _gens[i]->block_size(addr);
899 }
900 }
901 assert(false, "Some generation should contain the address");
902 return 0;
903 }
904
905 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
906 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
907 assert(block_start(addr) == addr, "addr must be a block start");
908 for (int i = 0; i < _n_gens; i++) {
909 if (_gens[i]->is_in_reserved(addr)) {
910 return _gens[i]->block_is_obj(addr);
911 }
912 }
913 assert(false, "Some generation should contain the address");
914 return false;
915 }
916
917 bool GenCollectedHeap::supports_tlab_allocation() const {
918 for (int i = 0; i < _n_gens; i += 1) {
919 if (_gens[i]->supports_tlab_allocation()) {
920 return true;
921 }
922 }
923 return false;
924 }
925
926 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
927 size_t result = 0;
928 for (int i = 0; i < _n_gens; i += 1) {
929 if (_gens[i]->supports_tlab_allocation()) {
930 result += _gens[i]->tlab_capacity();
931 }
932 }
933 return result;
934 }
935
936 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
937 size_t result = 0;
938 for (int i = 0; i < _n_gens; i += 1) {
939 if (_gens[i]->supports_tlab_allocation()) {
940 result += _gens[i]->unsafe_max_tlab_alloc();
941 }
942 }
943 return result;
944 }
945
946 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
947 bool gc_overhead_limit_was_exceeded;
948 return collector_policy()->mem_allocate_work(size /* size */,
949 true /* is_tlab */,
950 &gc_overhead_limit_was_exceeded);
951 }
952
953 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
954 // from the list headed by "*prev_ptr".
955 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
956 bool first = true;
957 size_t min_size = 0; // "first" makes this conceptually infinite.
958 ScratchBlock **smallest_ptr, *smallest;
959 ScratchBlock *cur = *prev_ptr;
960 while (cur) {
961 assert(*prev_ptr == cur, "just checking");
962 if (first || cur->num_words < min_size) {
963 smallest_ptr = prev_ptr;
964 smallest = cur;
965 min_size = smallest->num_words;
966 first = false;
967 }
968 prev_ptr = &cur->next;
969 cur = cur->next;
970 }
971 smallest = *smallest_ptr;
972 *smallest_ptr = smallest->next;
973 return smallest;
974 }
975
976 // Sort the scratch block list headed by res into decreasing size order,
977 // and set "res" to the result.
978 static void sort_scratch_list(ScratchBlock*& list) {
979 ScratchBlock* sorted = NULL;
980 ScratchBlock* unsorted = list;
981 while (unsorted) {
982 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
983 smallest->next = sorted;
984 sorted = smallest;
985 }
986 list = sorted;
987 }
988
989 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
990 size_t max_alloc_words) {
991 ScratchBlock* res = NULL;
992 for (int i = 0; i < _n_gens; i++) {
993 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
994 }
995 sort_scratch_list(res);
996 return res;
997 }
998
999 void GenCollectedHeap::release_scratch() {
1000 for (int i = 0; i < _n_gens; i++) {
1001 _gens[i]->reset_scratch();
1002 }
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
1018 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1019 bool old_to_young) {
1020 if (old_to_young) {
1021 for (int i = _n_gens-1; i >= 0; i--) {
1022 cl->do_generation(_gens[i]);
1023 }
1024 } else {
1025 for (int i = 0; i < _n_gens; i++) {
1026 cl->do_generation(_gens[i]);
1027 }
1028 }
1029 }
1030
1031 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1032 for (int i = 0; i < _n_gens; i++) {
1033 _gens[i]->space_iterate(cl, true);
1034 }
1035 }
1036
1037 bool GenCollectedHeap::is_maximal_no_gc() const {
1038 for (int i = 0; i < _n_gens; i++) {
1039 if (!_gens[i]->is_maximal_no_gc()) {
1040 return false;
1041 }
1042 }
1043 return true;
1044 }
1045
1046 void GenCollectedHeap::save_marks() {
1047 for (int i = 0; i < _n_gens; i++) {
1048 _gens[i]->save_marks();
1049 }
1050 }
1051
1052 GenCollectedHeap* GenCollectedHeap::heap() {
1053 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1054 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1055 return _gch;
1056 }
1057
1058
1059 void GenCollectedHeap::prepare_for_compaction() {
1060 guarantee(_n_gens = 2, "Wrong number of generations");
1061 Generation* old_gen = _gens[1];
1062 // Start by compacting into same gen.
1063 CompactPoint cp(old_gen, NULL, NULL);
1064 old_gen->prepare_for_compaction(&cp);
1065 Generation* young_gen = _gens[0];
1066 young_gen->prepare_for_compaction(&cp);
1067 }
1068
1069 GCStats* GenCollectedHeap::gc_stats(int level) const {
1070 return _gens[level]->gc_stats();
1071 }
1072
1073 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1074 for (int i = _n_gens-1; i >= 0; i--) {
1075 Generation* g = _gens[i];
1076 if (!silent) {
1077 gclog_or_tty->print(g->name());
1078 gclog_or_tty->print(" ");
1079 }
1080 g->verify();
1081 }
1082 if (!silent) {
1083 gclog_or_tty->print("remset ");
1084 }
1085 rem_set()->verify();
1086 }
1087
1088 void GenCollectedHeap::print_on(outputStream* st) const {
1089 for (int i = 0; i < _n_gens; i++) {
1090 _gens[i]->print_on(st);
1091 }
1092 MetaspaceAux::print_on(st);
1093 }
1094
1095 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1096 if (workers() != NULL) {
1097 workers()->threads_do(tc);
1098 }
1099 #if INCLUDE_ALL_GCS
1100 if (UseConcMarkSweepGC) {
1101 ConcurrentMarkSweepThread::threads_do(tc);
1102 }
1103 #endif // INCLUDE_ALL_GCS
1104 }
1105
1106 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1107 #if INCLUDE_ALL_GCS
1108 if (UseParNewGC) {
1109 workers()->print_worker_threads_on(st);
1110 }
1111 if (UseConcMarkSweepGC) {
1112 ConcurrentMarkSweepThread::print_all_on(st);
1113 }
1114 #endif // INCLUDE_ALL_GCS
1115 }
1116
1117 void GenCollectedHeap::print_on_error(outputStream* st) const {
1118 this->CollectedHeap::print_on_error(st);
1119
1120 #if INCLUDE_ALL_GCS
1121 if (UseConcMarkSweepGC) {
1122 st->cr();
1123 CMSCollector::print_on_error(st);
1124 }
1125 #endif // INCLUDE_ALL_GCS
1126 }
1127
1128 void GenCollectedHeap::print_tracing_info() const {
1129 if (TraceGen0Time) {
1130 get_gen(0)->print_summary_info();
1131 }
1132 if (TraceGen1Time) {
1133 get_gen(1)->print_summary_info();
1134 }
1135 }
1136
1137 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1138 if (PrintGCDetails && Verbose) {
1139 gclog_or_tty->print(" " SIZE_FORMAT
1140 "->" SIZE_FORMAT
1141 "(" SIZE_FORMAT ")",
1142 prev_used, used(), capacity());
1143 } else {
1144 gclog_or_tty->print(" " SIZE_FORMAT "K"
1145 "->" SIZE_FORMAT "K"
1146 "(" SIZE_FORMAT "K)",
1147 prev_used / K, used() / K, capacity() / K);
1148 }
1149 }
1150
1151 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1152 private:
1153 bool _full;
1154 public:
1155 void do_generation(Generation* gen) {
1156 gen->gc_prologue(_full);
1157 }
1158 GenGCPrologueClosure(bool full) : _full(full) {};
1159 };
1160
1161 void GenCollectedHeap::gc_prologue(bool full) {
1162 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1163
1164 always_do_update_barrier = false;
1165 // Fill TLAB's and such
1166 CollectedHeap::accumulate_statistics_all_tlabs();
1167 ensure_parsability(true); // retire TLABs
1168
1169 // Walk generations
1170 GenGCPrologueClosure blk(full);
1171 generation_iterate(&blk, false); // not old-to-young.
1172 };
1173
1174 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1175 private:
1176 bool _full;
1177 public:
1178 void do_generation(Generation* gen) {
1179 gen->gc_epilogue(_full);
1180 }
1181 GenGCEpilogueClosure(bool full) : _full(full) {};
1182 };
1183
1184 void GenCollectedHeap::gc_epilogue(bool full) {
1185 #ifdef COMPILER2
1186 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1187 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1188 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1189 #endif /* COMPILER2 */
1190
1191 resize_all_tlabs();
1192
1193 GenGCEpilogueClosure blk(full);
1194 generation_iterate(&blk, false); // not old-to-young.
1195
1196 if (!CleanChunkPoolAsync) {
1197 Chunk::clean_chunk_pool();
1198 }
1199
1200 MetaspaceCounters::update_performance_counters();
1201 CompressedClassSpaceCounters::update_performance_counters();
1202
1203 always_do_update_barrier = UseConcMarkSweepGC;
1204 };
1205
1206 #ifndef PRODUCT
1207 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1208 private:
1209 public:
1210 void do_generation(Generation* gen) {
1211 gen->record_spaces_top();
1212 }
1213 };
1214
1215 void GenCollectedHeap::record_gen_tops_before_GC() {
1216 if (ZapUnusedHeapArea) {
1217 GenGCSaveTopsBeforeGCClosure blk;
1218 generation_iterate(&blk, false); // not old-to-young.
1219 }
1220 }
1221 #endif // not PRODUCT
1222
1223 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1224 public:
1225 void do_generation(Generation* gen) {
1226 gen->ensure_parsability();
1227 }
1228 };
1229
1230 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1231 CollectedHeap::ensure_parsability(retire_tlabs);
1232 GenEnsureParsabilityClosure ep_cl;
1233 generation_iterate(&ep_cl, false);
1234 }
1235
1236 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1237 oop obj,
1238 size_t obj_size) {
1239 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1240 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1241 HeapWord* result = NULL;
1242
1243 result = old_gen->expand_and_allocate(obj_size, false);
1244
1245 if (result != NULL) {
1246 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1247 }
1248 return oop(result);
1249 }
1250
1251 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1252 jlong _time; // in ms
1253 jlong _now; // in ms
1254
1255 public:
1256 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1257
1258 jlong time() { return _time; }
1259
1260 void do_generation(Generation* gen) {
1261 _time = MIN2(_time, gen->time_of_last_gc(_now));
1262 }
1263 };
1264
1265 jlong GenCollectedHeap::millis_since_last_gc() {
1266 // We need a monotonically non-decreasing time in ms but
1267 // os::javaTimeMillis() does not guarantee monotonicity.
1268 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1269 GenTimeOfLastGCClosure tolgc_cl(now);
1270 // iterate over generations getting the oldest
1271 // time that a generation was collected
1272 generation_iterate(&tolgc_cl, false);
1273
1274 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1275 // provided the underlying platform provides such a time source
1276 // (and it is bug free). So we still have to guard against getting
1277 // back a time later than 'now'.
1278 jlong retVal = now - tolgc_cl.time();
1279 if (retVal < 0) {
1280 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, retVal);)
1281 return 0;
1282 }
1283 return retVal;
1284 }