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/generation.inline.hpp"
40 #include "memory/generationSpec.hpp"
41 #include "memory/resourceArea.hpp"
42 #include "memory/sharedHeap.hpp"
43 #include "memory/space.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/oop.inline2.hpp"
46 #include "runtime/biasedLocking.hpp"
47 #include "runtime/fprofiler.hpp"
48 #include "runtime/handles.hpp"
49 #include "runtime/handles.inline.hpp"
50 #include "runtime/java.hpp"
51 #include "runtime/vmThread.hpp"
52 #include "services/memoryService.hpp"
53 #include "utilities/vmError.hpp"
54 #include "utilities/workgroup.hpp"
55 #include "utilities/macros.hpp"
56 #if INCLUDE_ALL_GCS
57 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
58 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
59 #endif // INCLUDE_ALL_GCS
60
61 GenCollectedHeap* GenCollectedHeap::_gch;
62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
63
64 // The set of potentially parallel tasks in strong root scanning.
65 enum GCH_process_strong_roots_tasks {
66 // We probably want to parallelize both of these internally, but for now...
67 GCH_PS_younger_gens,
68 // Leave this one last.
69 GCH_PS_NumElements
70 };
71
72 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
73 SharedHeap(policy),
74 _gen_policy(policy),
75 _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
76 _full_collections_completed(0)
77 {
78 if (_gen_process_strong_tasks == NULL ||
79 !_gen_process_strong_tasks->valid()) {
80 vm_exit_during_initialization("Failed necessary allocation.");
81 }
82 assert(policy != NULL, "Sanity check");
83 }
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 int n_covered_regions = 0;
113 ReservedSpace heap_rs;
114
115 size_t heap_alignment = collector_policy()->heap_alignment();
116
117 heap_address = allocate(heap_alignment, &total_reserved,
118 &n_covered_regions, &heap_rs);
119
120 if (!heap_rs.is_reserved()) {
121 vm_shutdown_during_initialization(
122 "Could not reserve enough space for object heap");
123 return JNI_ENOMEM;
124 }
125
126 _reserved = MemRegion((HeapWord*)heap_rs.base(),
127 (HeapWord*)(heap_rs.base() + heap_rs.size()));
128
129 // It is important to do this in a way such that concurrent readers can't
130 // temporarily think something is in the heap. (Seen this happen in asserts.)
131 _reserved.set_word_size(0);
132 _reserved.set_start((HeapWord*)heap_rs.base());
133 size_t actual_heap_size = heap_rs.size();
134 _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
135
136 _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
137 set_barrier_set(rem_set()->bs());
138
139 _gch = this;
140
141 for (i = 0; i < _n_gens; i++) {
142 ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
143 _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
144 heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
145 }
146 clear_incremental_collection_failed();
147
148 #if INCLUDE_ALL_GCS
149 // If we are running CMS, create the collector responsible
150 // for collecting the CMS generations.
151 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
152 bool success = create_cms_collector();
153 if (!success) return JNI_ENOMEM;
154 }
155 #endif // INCLUDE_ALL_GCS
156
157 return JNI_OK;
158 }
159
160
161 char* GenCollectedHeap::allocate(size_t alignment,
162 size_t* _total_reserved,
163 int* _n_covered_regions,
164 ReservedSpace* heap_rs){
165 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
166 "the maximum representable size";
167
168 // Now figure out the total size.
169 size_t total_reserved = 0;
170 int n_covered_regions = 0;
171 const size_t pageSize = UseLargePages ?
172 os::large_page_size() : os::vm_page_size();
173
174 assert(alignment % pageSize == 0, "Must be");
175
176 for (int i = 0; i < _n_gens; i++) {
177 total_reserved += _gen_specs[i]->max_size();
178 if (total_reserved < _gen_specs[i]->max_size()) {
179 vm_exit_during_initialization(overflow_msg);
180 }
181 n_covered_regions += _gen_specs[i]->n_covered_regions();
182 }
183 assert(total_reserved % alignment == 0,
184 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
185 SIZE_FORMAT, total_reserved, alignment));
186
187 // Needed until the cardtable is fixed to have the right number
188 // of covered regions.
189 n_covered_regions += 2;
190
191 *_total_reserved = total_reserved;
192 *_n_covered_regions = n_covered_regions;
193
194 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
195 return heap_rs->base();
196 }
197
198
199 void GenCollectedHeap::post_initialize() {
200 SharedHeap::post_initialize();
201 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
202 guarantee(policy->is_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 "Wrong generation kind");
207
208 Generation* old_gen = get_gen(1);
209 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
210 old_gen->kind() == Generation::MarkSweepCompact,
211 "Wrong generation kind");
212
213 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
214 old_gen->capacity(),
215 def_new_gen->from()->capacity());
216 policy->initialize_gc_policy_counters();
217 }
218
219 void GenCollectedHeap::ref_processing_init() {
220 SharedHeap::ref_processing_init();
221 for (int i = 0; i < _n_gens; i++) {
222 _gens[i]->ref_processor_init();
223 }
224 }
225
226 size_t GenCollectedHeap::capacity() const {
227 size_t res = 0;
228 for (int i = 0; i < _n_gens; i++) {
229 res += _gens[i]->capacity();
230 }
231 return res;
232 }
233
234 size_t GenCollectedHeap::used() const {
235 size_t res = 0;
236 for (int i = 0; i < _n_gens; i++) {
237 res += _gens[i]->used();
238 }
239 return res;
240 }
241
242 // Save the "used_region" for generations level and lower.
243 void GenCollectedHeap::save_used_regions(int level) {
244 assert(level < _n_gens, "Illegal level parameter");
245 for (int i = level; i >= 0; i--) {
246 _gens[i]->save_used_region();
247 }
248 }
249
250 size_t GenCollectedHeap::max_capacity() const {
251 size_t res = 0;
252 for (int i = 0; i < _n_gens; i++) {
253 res += _gens[i]->max_capacity();
254 }
255 return res;
256 }
257
258 // Update the _full_collections_completed counter
259 // at the end of a stop-world full GC.
260 unsigned int GenCollectedHeap::update_full_collections_completed() {
261 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
262 assert(_full_collections_completed <= _total_full_collections,
263 "Can't complete more collections than were started");
264 _full_collections_completed = _total_full_collections;
265 ml.notify_all();
266 return _full_collections_completed;
267 }
268
269 // Update the _full_collections_completed counter, as appropriate,
270 // at the end of a concurrent GC cycle. Note the conditional update
271 // below to allow this method to be called by a concurrent collector
272 // without synchronizing in any manner with the VM thread (which
273 // may already have initiated a STW full collection "concurrently").
274 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
275 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
276 assert((_full_collections_completed <= _total_full_collections) &&
277 (count <= _total_full_collections),
278 "Can't complete more collections than were started");
279 if (count > _full_collections_completed) {
280 _full_collections_completed = count;
281 ml.notify_all();
282 }
283 return _full_collections_completed;
284 }
285
286
287 #ifndef PRODUCT
288 // Override of memory state checking method in CollectedHeap:
289 // Some collectors (CMS for example) can't have badHeapWordVal written
290 // in the first two words of an object. (For instance , in the case of
291 // CMS these words hold state used to synchronize between certain
292 // (concurrent) GC steps and direct allocating mutators.)
293 // The skip_header_HeapWords() method below, allows us to skip
294 // over the requisite number of HeapWord's. Note that (for
295 // generational collectors) this means that those many words are
296 // skipped in each object, irrespective of the generation in which
297 // that object lives. The resultant loss of precision seems to be
298 // harmless and the pain of avoiding that imprecision appears somewhat
299 // higher than we are prepared to pay for such rudimentary debugging
300 // support.
301 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
302 size_t size) {
303 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
304 // We are asked to check a size in HeapWords,
305 // but the memory is mangled in juint words.
306 juint* start = (juint*) (addr + skip_header_HeapWords());
307 juint* end = (juint*) (addr + size);
308 for (juint* slot = start; slot < end; slot += 1) {
309 assert(*slot == badHeapWordVal,
310 "Found non badHeapWordValue in pre-allocation check");
311 }
312 }
313 }
314 #endif
315
316 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
317 bool is_tlab,
318 bool first_only) {
319 HeapWord* res;
320 for (int i = 0; i < _n_gens; i++) {
321 if (_gens[i]->should_allocate(size, is_tlab)) {
322 res = _gens[i]->allocate(size, is_tlab);
323 if (res != NULL) return res;
324 else if (first_only) break;
325 }
326 }
327 // Otherwise...
328 return NULL;
329 }
330
331 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
332 bool* gc_overhead_limit_was_exceeded) {
333 return collector_policy()->mem_allocate_work(size,
334 false /* is_tlab */,
335 gc_overhead_limit_was_exceeded);
336 }
337
338 bool GenCollectedHeap::must_clear_all_soft_refs() {
339 return _gc_cause == GCCause::_last_ditch_collection;
340 }
341
342 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
343 return UseConcMarkSweepGC &&
344 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
345 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
346 }
347
348 void GenCollectedHeap::do_collection(bool full,
349 bool clear_all_soft_refs,
350 size_t size,
351 bool is_tlab,
352 int max_level) {
353 bool prepared_for_verification = false;
354 ResourceMark rm;
355 DEBUG_ONLY(Thread* my_thread = Thread::current();)
356
357 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
358 assert(my_thread->is_VM_thread() ||
359 my_thread->is_ConcurrentGC_thread(),
360 "incorrect thread type capability");
361 assert(Heap_lock->is_locked(),
362 "the requesting thread should have the Heap_lock");
363 guarantee(!is_gc_active(), "collection is not reentrant");
364 assert(max_level < n_gens(), "sanity check");
365
366 if (GC_locker::check_active_before_gc()) {
367 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
368 }
369
370 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
371 collector_policy()->should_clear_all_soft_refs();
372
373 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
374
375 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
376
377 print_heap_before_gc();
378
379 {
380 FlagSetting fl(_is_gc_active, true);
381
382 bool complete = full && (max_level == (n_gens()-1));
383 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
384 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
385 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
386 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
387 // so we can assume here that the next GC id is what we want.
388 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
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 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
422 // so we can assume here that the next GC id is what we want.
423 GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
424 TraceCollectorStats tcs(_gens[i]->counters());
425 TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
426
427 size_t prev_used = _gens[i]->used();
428 _gens[i]->stat_record()->invocations++;
429 _gens[i]->stat_record()->accumulated_time.start();
430
431 // Must be done anew before each collection because
432 // a previous collection will do mangling and will
433 // change top of some spaces.
434 record_gen_tops_before_GC();
435
436 if (PrintGC && Verbose) {
437 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
438 i,
439 _gens[i]->stat_record()->invocations,
440 size*HeapWordSize);
441 }
442
443 if (VerifyBeforeGC && i >= VerifyGCLevel &&
444 total_collections() >= VerifyGCStartAt) {
445 HandleMark hm; // Discard invalid handles created during verification
446 if (!prepared_for_verification) {
447 prepare_for_verify();
448 prepared_for_verification = true;
449 }
450 Universe::verify(" VerifyBeforeGC:");
451 }
452 COMPILER2_PRESENT(DerivedPointerTable::clear());
453
454 if (!must_restore_marks_for_biased_locking &&
455 _gens[i]->performs_in_place_marking()) {
456 // We perform this mark word preservation work lazily
457 // because it's only at this point that we know whether we
458 // absolutely have to do it; we want to avoid doing it for
459 // scavenge-only collections where it's unnecessary
460 must_restore_marks_for_biased_locking = true;
461 BiasedLocking::preserve_marks();
462 }
463
464 // Do collection work
465 {
466 // Note on ref discovery: For what appear to be historical reasons,
467 // GCH enables and disabled (by enqueing) refs discovery.
468 // In the future this should be moved into the generation's
469 // collect method so that ref discovery and enqueueing concerns
470 // are local to a generation. The collect method could return
471 // an appropriate indication in the case that notification on
472 // the ref lock was needed. This will make the treatment of
473 // weak refs more uniform (and indeed remove such concerns
474 // from GCH). XXX
475
476 HandleMark hm; // Discard invalid handles created during gc
477 save_marks(); // save marks for all gens
478 // We want to discover references, but not process them yet.
479 // This mode is disabled in process_discovered_references if the
480 // generation does some collection work, or in
481 // enqueue_discovered_references if the generation returns
482 // without doing any work.
483 ReferenceProcessor* rp = _gens[i]->ref_processor();
484 // If the discovery of ("weak") refs in this generation is
485 // atomic wrt other collectors in this configuration, we
486 // are guaranteed to have empty discovered ref lists.
487 if (rp->discovery_is_atomic()) {
488 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
489 rp->setup_policy(do_clear_all_soft_refs);
490 } else {
491 // collect() below will enable discovery as appropriate
492 }
493 _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
494 if (!rp->enqueuing_is_done()) {
495 rp->enqueue_discovered_references();
496 } else {
497 rp->set_enqueuing_is_done(false);
498 }
499 rp->verify_no_references_recorded();
500 }
501 max_level_collected = i;
502
503 // Determine if allocation request was met.
504 if (size > 0) {
505 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
506 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
507 size = 0;
508 }
509 }
510 }
511
512 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
513
514 _gens[i]->stat_record()->accumulated_time.stop();
515
516 update_gc_stats(i, full);
517
518 if (VerifyAfterGC && i >= VerifyGCLevel &&
519 total_collections() >= VerifyGCStartAt) {
520 HandleMark hm; // Discard invalid handles created during verification
521 Universe::verify(" VerifyAfterGC:");
522 }
523
524 if (PrintGCDetails) {
525 gclog_or_tty->print(":");
526 _gens[i]->print_heap_change(prev_used);
527 }
528 }
529 }
530
531 // Update "complete" boolean wrt what actually transpired --
532 // for instance, a promotion failure could have led to
533 // a whole heap collection.
534 complete = complete || (max_level_collected == n_gens() - 1);
535
536 if (complete) { // We did a "major" collection
537 // FIXME: See comment at pre_full_gc_dump call
538 post_full_gc_dump(NULL); // do any post full gc dumps
539 }
540
541 if (PrintGCDetails) {
542 print_heap_change(gch_prev_used);
543
544 // Print metaspace info for full GC with PrintGCDetails flag.
545 if (complete) {
546 MetaspaceAux::print_metaspace_change(metadata_prev_used);
547 }
548 }
549
550 for (int j = max_level_collected; j >= 0; j -= 1) {
551 // Adjust generation sizes.
552 _gens[j]->compute_new_size();
553 }
554
555 if (complete) {
556 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
557 ClassLoaderDataGraph::purge();
558 MetaspaceAux::verify_metrics();
559 // Resize the metaspace capacity after full collections
560 MetaspaceGC::compute_new_size();
561 update_full_collections_completed();
562 }
563
564 // Track memory usage and detect low memory after GC finishes
565 MemoryService::track_memory_usage();
566
567 gc_epilogue(complete);
568
569 if (must_restore_marks_for_biased_locking) {
570 BiasedLocking::restore_marks();
571 }
572 }
573
574 print_heap_after_gc();
575
576 #ifdef TRACESPINNING
577 ParallelTaskTerminator::print_termination_counts();
578 #endif
579 }
580
581 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
582 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
583 }
584
585 void GenCollectedHeap::set_par_threads(uint t) {
586 SharedHeap::set_par_threads(t);
587 _gen_process_strong_tasks->set_n_threads(t);
588 }
589
590 void GenCollectedHeap::
591 gen_process_strong_roots(int level,
592 bool younger_gens_as_roots,
593 bool activate_scope,
594 SharedHeap::ScanningOption so,
595 OopsInGenClosure* not_older_gens,
596 OopsInGenClosure* older_gens,
597 KlassClosure* klass_closure) {
598 // General strong roots.
599
600 SharedHeap::process_strong_roots(activate_scope, so,
601 not_older_gens, klass_closure);
602
603 if (younger_gens_as_roots) {
604 if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
605 for (int i = 0; i < level; i++) {
606 not_older_gens->set_generation(_gens[i]);
607 _gens[i]->oop_iterate(not_older_gens);
608 }
609 not_older_gens->reset_generation();
610 }
611 }
612 // When collection is parallel, all threads get to cooperate to do
613 // older-gen scanning.
614 for (int i = level+1; i < _n_gens; i++) {
615 older_gens->set_generation(_gens[i]);
616 rem_set()->younger_refs_iterate(_gens[i], older_gens);
617 older_gens->reset_generation();
618 }
619
620 _gen_process_strong_tasks->all_tasks_completed();
621 }
622
623 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
624 SharedHeap::process_weak_roots(root_closure);
625 // "Local" "weak" refs
626 for (int i = 0; i < _n_gens; i++) {
627 _gens[i]->ref_processor()->weak_oops_do(root_closure);
628 }
629 }
630
631 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
632 void GenCollectedHeap:: \
633 oop_since_save_marks_iterate(int level, \
634 OopClosureType* cur, \
635 OopClosureType* older) { \
636 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
637 for (int i = level+1; i < n_gens(); i++) { \
638 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
639 } \
640 }
641
642 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
643
644 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
645
646 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
647 for (int i = level; i < _n_gens; i++) {
648 if (!_gens[i]->no_allocs_since_save_marks()) return false;
649 }
650 return true;
651 }
652
653 bool GenCollectedHeap::supports_inline_contig_alloc() const {
654 return _gens[0]->supports_inline_contig_alloc();
655 }
656
657 HeapWord** GenCollectedHeap::top_addr() const {
658 return _gens[0]->top_addr();
659 }
660
661 HeapWord** GenCollectedHeap::end_addr() const {
662 return _gens[0]->end_addr();
663 }
664
665 // public collection interfaces
666
667 void GenCollectedHeap::collect(GCCause::Cause cause) {
668 if (should_do_concurrent_full_gc(cause)) {
669 #if INCLUDE_ALL_GCS
670 // mostly concurrent full collection
671 collect_mostly_concurrent(cause);
672 #else // INCLUDE_ALL_GCS
673 ShouldNotReachHere();
674 #endif // INCLUDE_ALL_GCS
675 } else {
676 #ifdef ASSERT
677 if (cause == GCCause::_scavenge_alot) {
678 // minor collection only
679 collect(cause, 0);
680 } else {
681 // Stop-the-world full collection
682 collect(cause, n_gens() - 1);
683 }
684 #else
685 // Stop-the-world full collection
686 collect(cause, n_gens() - 1);
687 #endif
688 }
689 }
690
691 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
692 // The caller doesn't have the Heap_lock
693 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
694 MutexLocker ml(Heap_lock);
695 collect_locked(cause, max_level);
696 }
697
698 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
699 // The caller has the Heap_lock
700 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
701 collect_locked(cause, n_gens() - 1);
702 }
703
704 // this is the private collection interface
705 // The Heap_lock is expected to be held on entry.
706
707 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
708 // Read the GC count while holding the Heap_lock
709 unsigned int gc_count_before = total_collections();
710 unsigned int full_gc_count_before = total_full_collections();
711 {
712 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
713 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
714 cause, max_level);
715 VMThread::execute(&op);
716 }
717 }
718
719 #if INCLUDE_ALL_GCS
720 bool GenCollectedHeap::create_cms_collector() {
721
722 assert(_gens[1]->kind() == Generation::ConcurrentMarkSweep,
723 "Unexpected generation kinds");
724 // Skip two header words in the block content verification
725 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
726 CMSCollector* collector = new CMSCollector(
727 (ConcurrentMarkSweepGeneration*)_gens[1],
728 _rem_set->as_CardTableRS(),
729 (ConcurrentMarkSweepPolicy*) collector_policy());
730
731 if (collector == NULL || !collector->completed_initialization()) {
732 if (collector) {
733 delete collector; // Be nice in embedded situation
734 }
735 vm_shutdown_during_initialization("Could not create CMS collector");
736 return false;
737 }
738 return true; // success
739 }
740
741 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
742 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
743
744 MutexLocker ml(Heap_lock);
745 // Read the GC counts while holding the Heap_lock
746 unsigned int full_gc_count_before = total_full_collections();
747 unsigned int gc_count_before = total_collections();
748 {
749 MutexUnlocker mu(Heap_lock);
750 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
751 VMThread::execute(&op);
752 }
753 }
754 #endif // INCLUDE_ALL_GCS
755
756 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
757 do_full_collection(clear_all_soft_refs, _n_gens - 1);
758 }
759
760 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
761 int max_level) {
762 int local_max_level;
763 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
764 gc_cause() == GCCause::_gc_locker) {
765 local_max_level = 0;
766 } else {
767 local_max_level = max_level;
768 }
769
770 do_collection(true /* full */,
771 clear_all_soft_refs /* clear_all_soft_refs */,
772 0 /* size */,
773 false /* is_tlab */,
774 local_max_level /* max_level */);
775 // Hack XXX FIX ME !!!
776 // A scavenge may not have been attempted, or may have
777 // been attempted and failed, because the old gen was too full
778 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
779 incremental_collection_will_fail(false /* don't consult_young */)) {
780 if (PrintGCDetails) {
781 gclog_or_tty->print_cr("GC locker: Trying a full collection "
782 "because scavenge failed");
783 }
784 // This time allow the old gen to be collected as well
785 do_collection(true /* full */,
786 clear_all_soft_refs /* clear_all_soft_refs */,
787 0 /* size */,
788 false /* is_tlab */,
789 n_gens() - 1 /* max_level */);
790 }
791 }
792
793 bool GenCollectedHeap::is_in_young(oop p) {
794 bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
795 assert(result == _gens[0]->is_in_reserved(p),
796 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
797 return result;
798 }
799
800 // Returns "TRUE" iff "p" points into the committed areas of the heap.
801 bool GenCollectedHeap::is_in(const void* p) const {
802 #ifndef ASSERT
803 guarantee(VerifyBeforeGC ||
804 VerifyDuringGC ||
805 VerifyBeforeExit ||
806 VerifyDuringStartup ||
807 PrintAssembly ||
808 tty->count() != 0 || // already printing
809 VerifyAfterGC ||
810 VMError::fatal_error_in_progress(), "too expensive");
811
812 #endif
813 // This might be sped up with a cache of the last generation that
814 // answered yes.
815 for (int i = 0; i < _n_gens; i++) {
816 if (_gens[i]->is_in(p)) return true;
817 }
818 // Otherwise...
819 return false;
820 }
821
822 #ifdef ASSERT
823 // Don't implement this by using is_in_young(). This method is used
824 // in some cases to check that is_in_young() is correct.
825 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
826 assert(is_in_reserved(p) || p == NULL,
827 "Does not work if address is non-null and outside of the heap");
828 return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
829 }
830 #endif
831
832 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
833 for (int i = 0; i < _n_gens; i++) {
834 _gens[i]->oop_iterate(cl);
835 }
836 }
837
838 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
839 for (int i = 0; i < _n_gens; i++) {
840 _gens[i]->object_iterate(cl);
841 }
842 }
843
844 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
845 for (int i = 0; i < _n_gens; i++) {
846 _gens[i]->safe_object_iterate(cl);
847 }
848 }
849
850 Space* GenCollectedHeap::space_containing(const void* addr) const {
851 for (int i = 0; i < _n_gens; i++) {
852 Space* res = _gens[i]->space_containing(addr);
853 if (res != NULL) return res;
854 }
855 // Otherwise...
856 assert(false, "Could not find containing space");
857 return NULL;
858 }
859
860
861 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
862 assert(is_in_reserved(addr), "block_start of address outside of heap");
863 for (int i = 0; i < _n_gens; i++) {
864 if (_gens[i]->is_in_reserved(addr)) {
865 assert(_gens[i]->is_in(addr),
866 "addr should be in allocated part of generation");
867 return _gens[i]->block_start(addr);
868 }
869 }
870 assert(false, "Some generation should contain the address");
871 return NULL;
872 }
873
874 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
875 assert(is_in_reserved(addr), "block_size of address outside of heap");
876 for (int i = 0; i < _n_gens; i++) {
877 if (_gens[i]->is_in_reserved(addr)) {
878 assert(_gens[i]->is_in(addr),
879 "addr should be in allocated part of generation");
880 return _gens[i]->block_size(addr);
881 }
882 }
883 assert(false, "Some generation should contain the address");
884 return 0;
885 }
886
887 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
888 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
889 assert(block_start(addr) == addr, "addr must be a block start");
890 for (int i = 0; i < _n_gens; i++) {
891 if (_gens[i]->is_in_reserved(addr)) {
892 return _gens[i]->block_is_obj(addr);
893 }
894 }
895 assert(false, "Some generation should contain the address");
896 return false;
897 }
898
899 bool GenCollectedHeap::supports_tlab_allocation() const {
900 for (int i = 0; i < _n_gens; i += 1) {
901 if (_gens[i]->supports_tlab_allocation()) {
902 return true;
903 }
904 }
905 return false;
906 }
907
908 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
909 size_t result = 0;
910 for (int i = 0; i < _n_gens; i += 1) {
911 if (_gens[i]->supports_tlab_allocation()) {
912 result += _gens[i]->tlab_capacity();
913 }
914 }
915 return result;
916 }
917
918 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
919 size_t result = 0;
920 for (int i = 0; i < _n_gens; i += 1) {
921 if (_gens[i]->supports_tlab_allocation()) {
922 result += _gens[i]->tlab_used();
923 }
924 }
925 return result;
926 }
927
928 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
929 size_t result = 0;
930 for (int i = 0; i < _n_gens; i += 1) {
931 if (_gens[i]->supports_tlab_allocation()) {
932 result += _gens[i]->unsafe_max_tlab_alloc();
933 }
934 }
935 return result;
936 }
937
938 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
939 bool gc_overhead_limit_was_exceeded;
940 return collector_policy()->mem_allocate_work(size /* size */,
941 true /* is_tlab */,
942 &gc_overhead_limit_was_exceeded);
943 }
944
945 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
946 // from the list headed by "*prev_ptr".
947 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
948 bool first = true;
949 size_t min_size = 0; // "first" makes this conceptually infinite.
950 ScratchBlock **smallest_ptr, *smallest;
951 ScratchBlock *cur = *prev_ptr;
952 while (cur) {
953 assert(*prev_ptr == cur, "just checking");
954 if (first || cur->num_words < min_size) {
955 smallest_ptr = prev_ptr;
956 smallest = cur;
957 min_size = smallest->num_words;
958 first = false;
959 }
960 prev_ptr = &cur->next;
961 cur = cur->next;
962 }
963 smallest = *smallest_ptr;
964 *smallest_ptr = smallest->next;
965 return smallest;
966 }
967
968 // Sort the scratch block list headed by res into decreasing size order,
969 // and set "res" to the result.
970 static void sort_scratch_list(ScratchBlock*& list) {
971 ScratchBlock* sorted = NULL;
972 ScratchBlock* unsorted = list;
973 while (unsorted) {
974 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
975 smallest->next = sorted;
976 sorted = smallest;
977 }
978 list = sorted;
979 }
980
981 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
982 size_t max_alloc_words) {
983 ScratchBlock* res = NULL;
984 for (int i = 0; i < _n_gens; i++) {
985 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
986 }
987 sort_scratch_list(res);
988 return res;
989 }
990
991 void GenCollectedHeap::release_scratch() {
992 for (int i = 0; i < _n_gens; i++) {
993 _gens[i]->reset_scratch();
994 }
995 }
996
997 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
998 void do_generation(Generation* gen) {
999 gen->prepare_for_verify();
1000 }
1001 };
1002
1003 void GenCollectedHeap::prepare_for_verify() {
1004 ensure_parsability(false); // no need to retire TLABs
1005 GenPrepareForVerifyClosure blk;
1006 generation_iterate(&blk, false);
1007 }
1008
1009
1010 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1011 bool old_to_young) {
1012 if (old_to_young) {
1013 for (int i = _n_gens-1; i >= 0; i--) {
1014 cl->do_generation(_gens[i]);
1015 }
1016 } else {
1017 for (int i = 0; i < _n_gens; i++) {
1018 cl->do_generation(_gens[i]);
1019 }
1020 }
1021 }
1022
1023 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1024 for (int i = 0; i < _n_gens; i++) {
1025 _gens[i]->space_iterate(cl, true);
1026 }
1027 }
1028
1029 bool GenCollectedHeap::is_maximal_no_gc() const {
1030 for (int i = 0; i < _n_gens; i++) {
1031 if (!_gens[i]->is_maximal_no_gc()) {
1032 return false;
1033 }
1034 }
1035 return true;
1036 }
1037
1038 void GenCollectedHeap::save_marks() {
1039 for (int i = 0; i < _n_gens; i++) {
1040 _gens[i]->save_marks();
1041 }
1042 }
1043
1044 GenCollectedHeap* GenCollectedHeap::heap() {
1045 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1046 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1047 return _gch;
1048 }
1049
1050
1051 void GenCollectedHeap::prepare_for_compaction() {
1052 guarantee(_n_gens = 2, "Wrong number of generations");
1053 Generation* old_gen = _gens[1];
1054 // Start by compacting into same gen.
1055 CompactPoint cp(old_gen, NULL, NULL);
1056 old_gen->prepare_for_compaction(&cp);
1057 Generation* young_gen = _gens[0];
1058 young_gen->prepare_for_compaction(&cp);
1059 }
1060
1061 GCStats* GenCollectedHeap::gc_stats(int level) const {
1062 return _gens[level]->gc_stats();
1063 }
1064
1065 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1066 for (int i = _n_gens-1; i >= 0; i--) {
1067 Generation* g = _gens[i];
1068 if (!silent) {
1069 gclog_or_tty->print("%s", g->name());
1070 gclog_or_tty->print(" ");
1071 }
1072 g->verify();
1073 }
1074 if (!silent) {
1075 gclog_or_tty->print("remset ");
1076 }
1077 rem_set()->verify();
1078 }
1079
1080 void GenCollectedHeap::print_on(outputStream* st) const {
1081 for (int i = 0; i < _n_gens; i++) {
1082 _gens[i]->print_on(st);
1083 }
1084 MetaspaceAux::print_on(st);
1085 }
1086
1087 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1088 if (workers() != NULL) {
1089 workers()->threads_do(tc);
1090 }
1091 #if INCLUDE_ALL_GCS
1092 if (UseConcMarkSweepGC) {
1093 ConcurrentMarkSweepThread::threads_do(tc);
1094 }
1095 #endif // INCLUDE_ALL_GCS
1096 }
1097
1098 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1099 #if INCLUDE_ALL_GCS
1100 if (UseParNewGC) {
1101 workers()->print_worker_threads_on(st);
1102 }
1103 if (UseConcMarkSweepGC) {
1104 ConcurrentMarkSweepThread::print_all_on(st);
1105 }
1106 #endif // INCLUDE_ALL_GCS
1107 }
1108
1109 void GenCollectedHeap::print_on_error(outputStream* st) const {
1110 this->CollectedHeap::print_on_error(st);
1111
1112 #if INCLUDE_ALL_GCS
1113 if (UseConcMarkSweepGC) {
1114 st->cr();
1115 CMSCollector::print_on_error(st);
1116 }
1117 #endif // INCLUDE_ALL_GCS
1118 }
1119
1120 void GenCollectedHeap::print_tracing_info() const {
1121 if (TraceYoungGenTime) {
1122 get_gen(0)->print_summary_info();
1123 }
1124 if (TraceOldGenTime) {
1125 get_gen(1)->print_summary_info();
1126 }
1127 }
1128
1129 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1130 if (PrintGCDetails && Verbose) {
1131 gclog_or_tty->print(" " SIZE_FORMAT
1132 "->" SIZE_FORMAT
1133 "(" SIZE_FORMAT ")",
1134 prev_used, used(), capacity());
1135 } else {
1136 gclog_or_tty->print(" " SIZE_FORMAT "K"
1137 "->" SIZE_FORMAT "K"
1138 "(" SIZE_FORMAT "K)",
1139 prev_used / K, used() / K, capacity() / K);
1140 }
1141 }
1142
1143 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1144 private:
1145 bool _full;
1146 public:
1147 void do_generation(Generation* gen) {
1148 gen->gc_prologue(_full);
1149 }
1150 GenGCPrologueClosure(bool full) : _full(full) {};
1151 };
1152
1153 void GenCollectedHeap::gc_prologue(bool full) {
1154 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1155
1156 always_do_update_barrier = false;
1157 // Fill TLAB's and such
1158 CollectedHeap::accumulate_statistics_all_tlabs();
1159 ensure_parsability(true); // retire TLABs
1160
1161 // Walk generations
1162 GenGCPrologueClosure blk(full);
1163 generation_iterate(&blk, false); // not old-to-young.
1164 };
1165
1166 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1167 private:
1168 bool _full;
1169 public:
1170 void do_generation(Generation* gen) {
1171 gen->gc_epilogue(_full);
1172 }
1173 GenGCEpilogueClosure(bool full) : _full(full) {};
1174 };
1175
1176 void GenCollectedHeap::gc_epilogue(bool full) {
1177 #ifdef COMPILER2
1178 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1179 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1180 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1181 #endif /* COMPILER2 */
1182
1183 resize_all_tlabs();
1184
1185 GenGCEpilogueClosure blk(full);
1186 generation_iterate(&blk, false); // not old-to-young.
1187
1188 if (!CleanChunkPoolAsync) {
1189 Chunk::clean_chunk_pool();
1190 }
1191
1192 MetaspaceCounters::update_performance_counters();
1193 CompressedClassSpaceCounters::update_performance_counters();
1194
1195 always_do_update_barrier = UseConcMarkSweepGC;
1196 };
1197
1198 #ifndef PRODUCT
1199 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1200 private:
1201 public:
1202 void do_generation(Generation* gen) {
1203 gen->record_spaces_top();
1204 }
1205 };
1206
1207 void GenCollectedHeap::record_gen_tops_before_GC() {
1208 if (ZapUnusedHeapArea) {
1209 GenGCSaveTopsBeforeGCClosure blk;
1210 generation_iterate(&blk, false); // not old-to-young.
1211 }
1212 }
1213 #endif // not PRODUCT
1214
1215 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1216 public:
1217 void do_generation(Generation* gen) {
1218 gen->ensure_parsability();
1219 }
1220 };
1221
1222 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1223 CollectedHeap::ensure_parsability(retire_tlabs);
1224 GenEnsureParsabilityClosure ep_cl;
1225 generation_iterate(&ep_cl, false);
1226 }
1227
1228 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1229 oop obj,
1230 size_t obj_size) {
1231 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1232 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1233 HeapWord* result = NULL;
1234
1235 result = old_gen->expand_and_allocate(obj_size, false);
1236
1237 if (result != NULL) {
1238 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1239 }
1240 return oop(result);
1241 }
1242
1243 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1244 jlong _time; // in ms
1245 jlong _now; // in ms
1246
1247 public:
1248 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1249
1250 jlong time() { return _time; }
1251
1252 void do_generation(Generation* gen) {
1253 _time = MIN2(_time, gen->time_of_last_gc(_now));
1254 }
1255 };
1256
1257 jlong GenCollectedHeap::millis_since_last_gc() {
1258 // We need a monotonically non-decreasing time in ms but
1259 // os::javaTimeMillis() does not guarantee monotonicity.
1260 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1261 GenTimeOfLastGCClosure tolgc_cl(now);
1262 // iterate over generations getting the oldest
1263 // time that a generation was collected
1264 generation_iterate(&tolgc_cl, false);
1265
1266 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1267 // provided the underlying platform provides such a time source
1268 // (and it is bug free). So we still have to guard against getting
1269 // back a time later than 'now'.
1270 jlong retVal = now - tolgc_cl.time();
1271 if (retVal < 0) {
1272 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1273 return 0;
1274 }
1275 return retVal;
1276 }