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 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
201 guarantee(policy->is_generation_policy(), "Illegal policy type");
202 DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
203 assert(def_new_gen->kind() == Generation::DefNew ||
204 def_new_gen->kind() == Generation::ParNew ||
205 def_new_gen->kind() == Generation::ASParNew,
206 "Wrong generation kind");
207
208 Generation* old_gen = get_gen(1);
209 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
210 old_gen->kind() == Generation::ASConcurrentMarkSweep ||
211 old_gen->kind() == Generation::MarkSweepCompact,
212 "Wrong generation kind");
213
214 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
215 old_gen->capacity(),
216 def_new_gen->from()->capacity());
217 policy->initialize_gc_policy_counters();
218 }
219
220 void GenCollectedHeap::ref_processing_init() {
221 SharedHeap::ref_processing_init();
222 for (int i = 0; i < _n_gens; i++) {
223 _gens[i]->ref_processor_init();
224 }
225 }
226
227 size_t GenCollectedHeap::capacity() const {
228 size_t res = 0;
229 for (int i = 0; i < _n_gens; i++) {
230 res += _gens[i]->capacity();
231 }
232 return res;
233 }
234
235 size_t GenCollectedHeap::used() const {
236 size_t res = 0;
237 for (int i = 0; i < _n_gens; i++) {
238 res += _gens[i]->used();
239 }
240 return res;
241 }
242
243 // Save the "used_region" for generations level and lower.
244 void GenCollectedHeap::save_used_regions(int level) {
245 assert(level < _n_gens, "Illegal level parameter");
246 for (int i = level; i >= 0; i--) {
247 _gens[i]->save_used_region();
248 }
249 }
250
251 size_t GenCollectedHeap::max_capacity() const {
252 size_t res = 0;
253 for (int i = 0; i < _n_gens; i++) {
254 res += _gens[i]->max_capacity();
255 }
256 return res;
257 }
258
259 // Update the _full_collections_completed counter
260 // at the end of a stop-world full GC.
261 unsigned int GenCollectedHeap::update_full_collections_completed() {
262 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
263 assert(_full_collections_completed <= _total_full_collections,
264 "Can't complete more collections than were started");
265 _full_collections_completed = _total_full_collections;
266 ml.notify_all();
267 return _full_collections_completed;
268 }
269
270 // Update the _full_collections_completed counter, as appropriate,
271 // at the end of a concurrent GC cycle. Note the conditional update
272 // below to allow this method to be called by a concurrent collector
273 // without synchronizing in any manner with the VM thread (which
274 // may already have initiated a STW full collection "concurrently").
275 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
276 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
277 assert((_full_collections_completed <= _total_full_collections) &&
278 (count <= _total_full_collections),
279 "Can't complete more collections than were started");
280 if (count > _full_collections_completed) {
281 _full_collections_completed = count;
282 ml.notify_all();
283 }
284 return _full_collections_completed;
285 }
286
287
288 #ifndef PRODUCT
289 // Override of memory state checking method in CollectedHeap:
290 // Some collectors (CMS for example) can't have badHeapWordVal written
291 // in the first two words of an object. (For instance , in the case of
292 // CMS these words hold state used to synchronize between certain
293 // (concurrent) GC steps and direct allocating mutators.)
294 // The skip_header_HeapWords() method below, allows us to skip
295 // over the requisite number of HeapWord's. Note that (for
296 // generational collectors) this means that those many words are
297 // skipped in each object, irrespective of the generation in which
298 // that object lives. The resultant loss of precision seems to be
299 // harmless and the pain of avoiding that imprecision appears somewhat
300 // higher than we are prepared to pay for such rudimentary debugging
301 // support.
302 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
303 size_t size) {
304 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
305 // We are asked to check a size in HeapWords,
306 // but the memory is mangled in juint words.
307 juint* start = (juint*) (addr + skip_header_HeapWords());
308 juint* end = (juint*) (addr + size);
309 for (juint* slot = start; slot < end; slot += 1) {
310 assert(*slot == badHeapWordVal,
311 "Found non badHeapWordValue in pre-allocation check");
312 }
313 }
314 }
315 #endif
316
317 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
318 bool is_tlab,
319 bool first_only) {
320 HeapWord* res;
321 for (int i = 0; i < _n_gens; i++) {
322 if (_gens[i]->should_allocate(size, is_tlab)) {
323 res = _gens[i]->allocate(size, is_tlab);
324 if (res != NULL) return res;
325 else if (first_only) break;
326 }
327 }
328 // Otherwise...
329 return NULL;
330 }
331
332 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
333 bool* gc_overhead_limit_was_exceeded) {
334 return collector_policy()->mem_allocate_work(size,
335 false /* is_tlab */,
336 gc_overhead_limit_was_exceeded);
337 }
338
339 bool GenCollectedHeap::must_clear_all_soft_refs() {
340 return _gc_cause == GCCause::_last_ditch_collection;
341 }
342
343 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
344 return UseConcMarkSweepGC &&
345 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
346 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
347 }
348
349 void GenCollectedHeap::do_collection(bool full,
350 bool clear_all_soft_refs,
351 size_t size,
352 bool is_tlab,
353 int max_level) {
354 bool prepared_for_verification = false;
355 ResourceMark rm;
356 DEBUG_ONLY(Thread* my_thread = Thread::current();)
357
358 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
359 assert(my_thread->is_VM_thread() ||
360 my_thread->is_ConcurrentGC_thread(),
361 "incorrect thread type capability");
362 assert(Heap_lock->is_locked(),
363 "the requesting thread should have the Heap_lock");
364 guarantee(!is_gc_active(), "collection is not reentrant");
365 assert(max_level < n_gens(), "sanity check");
366
367 if (GC_locker::check_active_before_gc()) {
368 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
369 }
370
371 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
372 collector_policy()->should_clear_all_soft_refs();
373
374 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
375
376 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
377
378 print_heap_before_gc();
379
380 {
381 FlagSetting fl(_is_gc_active, true);
382
383 bool complete = full && (max_level == (n_gens()-1));
384 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
385 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
386 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
387 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL);
388
389 gc_prologue(complete);
390 increment_total_collections(complete);
391
392 size_t gch_prev_used = used();
393
394 int starting_level = 0;
395 if (full) {
396 // Search for the oldest generation which will collect all younger
397 // generations, and start collection loop there.
398 for (int i = max_level; i >= 0; i--) {
399 if (_gens[i]->full_collects_younger_generations()) {
400 starting_level = i;
401 break;
402 }
403 }
404 }
405
406 bool must_restore_marks_for_biased_locking = false;
407
408 int max_level_collected = starting_level;
409 for (int i = starting_level; i <= max_level; i++) {
410 if (_gens[i]->should_collect(full, size, is_tlab)) {
411 if (i == n_gens() - 1) { // a major collection is to happen
412 if (!complete) {
413 // The full_collections increment was missed above.
414 increment_total_full_collections();
415 }
416 pre_full_gc_dump(NULL); // do any pre full gc dumps
417 }
418 // Timer for individual generations. Last argument is false: no CR
419 // FIXME: We should try to start the timing earlier to cover more of the GC pause
420 GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL);
421 TraceCollectorStats tcs(_gens[i]->counters());
422 TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
423
424 size_t prev_used = _gens[i]->used();
425 _gens[i]->stat_record()->invocations++;
426 _gens[i]->stat_record()->accumulated_time.start();
427
428 // Must be done anew before each collection because
429 // a previous collection will do mangling and will
430 // change top of some spaces.
431 record_gen_tops_before_GC();
432
433 if (PrintGC && Verbose) {
434 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
435 i,
436 _gens[i]->stat_record()->invocations,
437 size*HeapWordSize);
438 }
439
440 if (VerifyBeforeGC && i >= VerifyGCLevel &&
441 total_collections() >= VerifyGCStartAt) {
442 HandleMark hm; // Discard invalid handles created during verification
443 if (!prepared_for_verification) {
444 prepare_for_verify();
445 prepared_for_verification = true;
446 }
447 Universe::verify(" VerifyBeforeGC:");
448 }
449 COMPILER2_PRESENT(DerivedPointerTable::clear());
450
451 if (!must_restore_marks_for_biased_locking &&
452 _gens[i]->performs_in_place_marking()) {
453 // We perform this mark word preservation work lazily
454 // because it's only at this point that we know whether we
455 // absolutely have to do it; we want to avoid doing it for
456 // scavenge-only collections where it's unnecessary
457 must_restore_marks_for_biased_locking = true;
458 BiasedLocking::preserve_marks();
459 }
460
461 // Do collection work
462 {
463 // Note on ref discovery: For what appear to be historical reasons,
464 // GCH enables and disabled (by enqueing) refs discovery.
465 // In the future this should be moved into the generation's
466 // collect method so that ref discovery and enqueueing concerns
467 // are local to a generation. The collect method could return
468 // an appropriate indication in the case that notification on
469 // the ref lock was needed. This will make the treatment of
470 // weak refs more uniform (and indeed remove such concerns
471 // from GCH). XXX
472
473 HandleMark hm; // Discard invalid handles created during gc
474 save_marks(); // save marks for all gens
475 // We want to discover references, but not process them yet.
476 // This mode is disabled in process_discovered_references if the
477 // generation does some collection work, or in
478 // enqueue_discovered_references if the generation returns
479 // without doing any work.
480 ReferenceProcessor* rp = _gens[i]->ref_processor();
481 // If the discovery of ("weak") refs in this generation is
482 // atomic wrt other collectors in this configuration, we
483 // are guaranteed to have empty discovered ref lists.
484 if (rp->discovery_is_atomic()) {
485 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
486 rp->setup_policy(do_clear_all_soft_refs);
487 } else {
488 // collect() below will enable discovery as appropriate
489 }
490 _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
491 if (!rp->enqueuing_is_done()) {
492 rp->enqueue_discovered_references();
493 } else {
494 rp->set_enqueuing_is_done(false);
495 }
496 rp->verify_no_references_recorded();
497 }
498 max_level_collected = i;
499
500 // Determine if allocation request was met.
501 if (size > 0) {
502 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
503 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
504 size = 0;
505 }
506 }
507 }
508
509 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
510
511 _gens[i]->stat_record()->accumulated_time.stop();
512
513 update_gc_stats(i, full);
514
515 if (VerifyAfterGC && i >= VerifyGCLevel &&
516 total_collections() >= VerifyGCStartAt) {
517 HandleMark hm; // Discard invalid handles created during verification
518 Universe::verify(" VerifyAfterGC:");
519 }
520
521 if (PrintGCDetails) {
522 gclog_or_tty->print(":");
523 _gens[i]->print_heap_change(prev_used);
524 }
525 }
526 }
527
528 // Update "complete" boolean wrt what actually transpired --
529 // for instance, a promotion failure could have led to
530 // a whole heap collection.
531 complete = complete || (max_level_collected == n_gens() - 1);
532
533 if (complete) { // We did a "major" collection
534 // FIXME: See comment at pre_full_gc_dump call
535 post_full_gc_dump(NULL); // do any post full gc dumps
536 }
537
538 if (PrintGCDetails) {
539 print_heap_change(gch_prev_used);
540
541 // Print metaspace info for full GC with PrintGCDetails flag.
542 if (complete) {
543 MetaspaceAux::print_metaspace_change(metadata_prev_used);
544 }
545 }
546
547 for (int j = max_level_collected; j >= 0; j -= 1) {
548 // Adjust generation sizes.
549 _gens[j]->compute_new_size();
550 }
551
552 if (complete) {
553 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
554 ClassLoaderDataGraph::purge();
555 MetaspaceAux::verify_metrics();
556 // Resize the metaspace capacity after full collections
557 MetaspaceGC::compute_new_size();
558 update_full_collections_completed();
559 }
560
561 // Track memory usage and detect low memory after GC finishes
562 MemoryService::track_memory_usage();
563
564 gc_epilogue(complete);
565
566 if (must_restore_marks_for_biased_locking) {
567 BiasedLocking::restore_marks();
568 }
569 }
570
571 AdaptiveSizePolicy* sp = gen_policy()->size_policy();
572 AdaptiveSizePolicyOutput(sp, total_collections());
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 (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)),
724 "Unexpected generation kinds");
725 // Skip two header words in the block content verification
726 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
727 CMSCollector* collector = new CMSCollector(
728 (ConcurrentMarkSweepGeneration*)_gens[1],
729 _rem_set->as_CardTableRS(),
730 (ConcurrentMarkSweepPolicy*) collector_policy());
731
732 if (collector == NULL || !collector->completed_initialization()) {
733 if (collector) {
734 delete collector; // Be nice in embedded situation
735 }
736 vm_shutdown_during_initialization("Could not create CMS collector");
737 return false;
738 }
739 return true; // success
740 }
741
742 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
743 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
744
745 MutexLocker ml(Heap_lock);
746 // Read the GC counts while holding the Heap_lock
747 unsigned int full_gc_count_before = total_full_collections();
748 unsigned int gc_count_before = total_collections();
749 {
750 MutexUnlocker mu(Heap_lock);
751 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
752 VMThread::execute(&op);
753 }
754 }
755 #endif // INCLUDE_ALL_GCS
756
757 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
758 do_full_collection(clear_all_soft_refs, _n_gens - 1);
759 }
760
761 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
762 int max_level) {
763 int local_max_level;
764 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
765 gc_cause() == GCCause::_gc_locker) {
766 local_max_level = 0;
767 } else {
768 local_max_level = max_level;
769 }
770
771 do_collection(true /* full */,
772 clear_all_soft_refs /* clear_all_soft_refs */,
773 0 /* size */,
774 false /* is_tlab */,
775 local_max_level /* max_level */);
776 // Hack XXX FIX ME !!!
777 // A scavenge may not have been attempted, or may have
778 // been attempted and failed, because the old gen was too full
779 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
780 incremental_collection_will_fail(false /* don't consult_young */)) {
781 if (PrintGCDetails) {
782 gclog_or_tty->print_cr("GC locker: Trying a full collection "
783 "because scavenge failed");
784 }
785 // This time allow the old gen to be collected as well
786 do_collection(true /* full */,
787 clear_all_soft_refs /* clear_all_soft_refs */,
788 0 /* size */,
789 false /* is_tlab */,
790 n_gens() - 1 /* max_level */);
791 }
792 }
793
794 bool GenCollectedHeap::is_in_young(oop p) {
795 bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
796 assert(result == _gens[0]->is_in_reserved(p),
797 err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, (void*)p));
798 return result;
799 }
800
801 // Returns "TRUE" iff "p" points into the committed areas of the heap.
802 bool GenCollectedHeap::is_in(const void* p) const {
803 #ifndef ASSERT
804 guarantee(VerifyBeforeGC ||
805 VerifyDuringGC ||
806 VerifyBeforeExit ||
807 VerifyDuringStartup ||
808 PrintAssembly ||
809 tty->count() != 0 || // already printing
810 VerifyAfterGC ||
811 VMError::fatal_error_in_progress(), "too expensive");
812
813 #endif
814 // This might be sped up with a cache of the last generation that
815 // answered yes.
816 for (int i = 0; i < _n_gens; i++) {
817 if (_gens[i]->is_in(p)) return true;
818 }
819 // Otherwise...
820 return false;
821 }
822
823 #ifdef ASSERT
824 // Don't implement this by using is_in_young(). This method is used
825 // in some cases to check that is_in_young() is correct.
826 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
827 assert(is_in_reserved(p) || p == NULL,
828 "Does not work if address is non-null and outside of the heap");
829 return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
830 }
831 #endif
832
833 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
834 for (int i = 0; i < _n_gens; i++) {
835 _gens[i]->oop_iterate(cl);
836 }
837 }
838
839 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
840 for (int i = 0; i < _n_gens; i++) {
841 _gens[i]->object_iterate(cl);
842 }
843 }
844
845 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
846 for (int i = 0; i < _n_gens; i++) {
847 _gens[i]->safe_object_iterate(cl);
848 }
849 }
850
851 Space* GenCollectedHeap::space_containing(const void* addr) const {
852 for (int i = 0; i < _n_gens; i++) {
853 Space* res = _gens[i]->space_containing(addr);
854 if (res != NULL) return res;
855 }
856 // Otherwise...
857 assert(false, "Could not find containing space");
858 return NULL;
859 }
860
861
862 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
863 assert(is_in_reserved(addr), "block_start of address outside of heap");
864 for (int i = 0; i < _n_gens; i++) {
865 if (_gens[i]->is_in_reserved(addr)) {
866 assert(_gens[i]->is_in(addr),
867 "addr should be in allocated part of generation");
868 return _gens[i]->block_start(addr);
869 }
870 }
871 assert(false, "Some generation should contain the address");
872 return NULL;
873 }
874
875 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
876 assert(is_in_reserved(addr), "block_size of address outside of heap");
877 for (int i = 0; i < _n_gens; i++) {
878 if (_gens[i]->is_in_reserved(addr)) {
879 assert(_gens[i]->is_in(addr),
880 "addr should be in allocated part of generation");
881 return _gens[i]->block_size(addr);
882 }
883 }
884 assert(false, "Some generation should contain the address");
885 return 0;
886 }
887
888 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
889 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
890 assert(block_start(addr) == addr, "addr must be a block start");
891 for (int i = 0; i < _n_gens; i++) {
892 if (_gens[i]->is_in_reserved(addr)) {
893 return _gens[i]->block_is_obj(addr);
894 }
895 }
896 assert(false, "Some generation should contain the address");
897 return false;
898 }
899
900 bool GenCollectedHeap::supports_tlab_allocation() const {
901 for (int i = 0; i < _n_gens; i += 1) {
902 if (_gens[i]->supports_tlab_allocation()) {
903 return true;
904 }
905 }
906 return false;
907 }
908
909 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
910 size_t result = 0;
911 for (int i = 0; i < _n_gens; i += 1) {
912 if (_gens[i]->supports_tlab_allocation()) {
913 result += _gens[i]->tlab_capacity();
914 }
915 }
916 return result;
917 }
918
919 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
920 size_t result = 0;
921 for (int i = 0; i < _n_gens; i += 1) {
922 if (_gens[i]->supports_tlab_allocation()) {
923 result += _gens[i]->tlab_used();
924 }
925 }
926 return result;
927 }
928
929 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
930 size_t result = 0;
931 for (int i = 0; i < _n_gens; i += 1) {
932 if (_gens[i]->supports_tlab_allocation()) {
933 result += _gens[i]->unsafe_max_tlab_alloc();
934 }
935 }
936 return result;
937 }
938
939 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
940 bool gc_overhead_limit_was_exceeded;
941 return collector_policy()->mem_allocate_work(size /* size */,
942 true /* is_tlab */,
943 &gc_overhead_limit_was_exceeded);
944 }
945
946 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
947 // from the list headed by "*prev_ptr".
948 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
949 bool first = true;
950 size_t min_size = 0; // "first" makes this conceptually infinite.
951 ScratchBlock **smallest_ptr, *smallest;
952 ScratchBlock *cur = *prev_ptr;
953 while (cur) {
954 assert(*prev_ptr == cur, "just checking");
955 if (first || cur->num_words < min_size) {
956 smallest_ptr = prev_ptr;
957 smallest = cur;
958 min_size = smallest->num_words;
959 first = false;
960 }
961 prev_ptr = &cur->next;
962 cur = cur->next;
963 }
964 smallest = *smallest_ptr;
965 *smallest_ptr = smallest->next;
966 return smallest;
967 }
968
969 // Sort the scratch block list headed by res into decreasing size order,
970 // and set "res" to the result.
971 static void sort_scratch_list(ScratchBlock*& list) {
972 ScratchBlock* sorted = NULL;
973 ScratchBlock* unsorted = list;
974 while (unsorted) {
975 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
976 smallest->next = sorted;
977 sorted = smallest;
978 }
979 list = sorted;
980 }
981
982 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
983 size_t max_alloc_words) {
984 ScratchBlock* res = NULL;
985 for (int i = 0; i < _n_gens; i++) {
986 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
987 }
988 sort_scratch_list(res);
989 return res;
990 }
991
992 void GenCollectedHeap::release_scratch() {
993 for (int i = 0; i < _n_gens; i++) {
994 _gens[i]->reset_scratch();
995 }
996 }
997
998 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
999 void do_generation(Generation* gen) {
1000 gen->prepare_for_verify();
1001 }
1002 };
1003
1004 void GenCollectedHeap::prepare_for_verify() {
1005 ensure_parsability(false); // no need to retire TLABs
1006 GenPrepareForVerifyClosure blk;
1007 generation_iterate(&blk, false);
1008 }
1009
1010
1011 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1012 bool old_to_young) {
1013 if (old_to_young) {
1014 for (int i = _n_gens-1; i >= 0; i--) {
1015 cl->do_generation(_gens[i]);
1016 }
1017 } else {
1018 for (int i = 0; i < _n_gens; i++) {
1019 cl->do_generation(_gens[i]);
1020 }
1021 }
1022 }
1023
1024 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1025 for (int i = 0; i < _n_gens; i++) {
1026 _gens[i]->space_iterate(cl, true);
1027 }
1028 }
1029
1030 bool GenCollectedHeap::is_maximal_no_gc() const {
1031 for (int i = 0; i < _n_gens; i++) {
1032 if (!_gens[i]->is_maximal_no_gc()) {
1033 return false;
1034 }
1035 }
1036 return true;
1037 }
1038
1039 void GenCollectedHeap::save_marks() {
1040 for (int i = 0; i < _n_gens; i++) {
1041 _gens[i]->save_marks();
1042 }
1043 }
1044
1045 GenCollectedHeap* GenCollectedHeap::heap() {
1046 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1047 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1048 return _gch;
1049 }
1050
1051
1052 void GenCollectedHeap::prepare_for_compaction() {
1053 guarantee(_n_gens = 2, "Wrong number of generations");
1054 Generation* old_gen = _gens[1];
1055 // Start by compacting into same gen.
1056 CompactPoint cp(old_gen, NULL, NULL);
1057 old_gen->prepare_for_compaction(&cp);
1058 Generation* young_gen = _gens[0];
1059 young_gen->prepare_for_compaction(&cp);
1060 }
1061
1062 GCStats* GenCollectedHeap::gc_stats(int level) const {
1063 return _gens[level]->gc_stats();
1064 }
1065
1066 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1067 for (int i = _n_gens-1; i >= 0; i--) {
1068 Generation* g = _gens[i];
1069 if (!silent) {
1070 gclog_or_tty->print(g->name());
1071 gclog_or_tty->print(" ");
1072 }
1073 g->verify();
1074 }
1075 if (!silent) {
1076 gclog_or_tty->print("remset ");
1077 }
1078 rem_set()->verify();
1079 }
1080
1081 void GenCollectedHeap::print_on(outputStream* st) const {
1082 for (int i = 0; i < _n_gens; i++) {
1083 _gens[i]->print_on(st);
1084 }
1085 MetaspaceAux::print_on(st);
1086 }
1087
1088 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1089 if (workers() != NULL) {
1090 workers()->threads_do(tc);
1091 }
1092 #if INCLUDE_ALL_GCS
1093 if (UseConcMarkSweepGC) {
1094 ConcurrentMarkSweepThread::threads_do(tc);
1095 }
1096 #endif // INCLUDE_ALL_GCS
1097 }
1098
1099 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1100 #if INCLUDE_ALL_GCS
1101 if (UseParNewGC) {
1102 workers()->print_worker_threads_on(st);
1103 }
1104 if (UseConcMarkSweepGC) {
1105 ConcurrentMarkSweepThread::print_all_on(st);
1106 }
1107 #endif // INCLUDE_ALL_GCS
1108 }
1109
1110 void GenCollectedHeap::print_on_error(outputStream* st) const {
1111 this->CollectedHeap::print_on_error(st);
1112
1113 #if INCLUDE_ALL_GCS
1114 if (UseConcMarkSweepGC) {
1115 st->cr();
1116 CMSCollector::print_on_error(st);
1117 }
1118 #endif // INCLUDE_ALL_GCS
1119 }
1120
1121 void GenCollectedHeap::print_tracing_info() const {
1122 if (TraceGen0Time) {
1123 get_gen(0)->print_summary_info();
1124 }
1125 if (TraceGen1Time) {
1126 get_gen(1)->print_summary_info();
1127 }
1128 }
1129
1130 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1131 if (PrintGCDetails && Verbose) {
1132 gclog_or_tty->print(" " SIZE_FORMAT
1133 "->" SIZE_FORMAT
1134 "(" SIZE_FORMAT ")",
1135 prev_used, used(), capacity());
1136 } else {
1137 gclog_or_tty->print(" " SIZE_FORMAT "K"
1138 "->" SIZE_FORMAT "K"
1139 "(" SIZE_FORMAT "K)",
1140 prev_used / K, used() / K, capacity() / K);
1141 }
1142 }
1143
1144 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1145 private:
1146 bool _full;
1147 public:
1148 void do_generation(Generation* gen) {
1149 gen->gc_prologue(_full);
1150 }
1151 GenGCPrologueClosure(bool full) : _full(full) {};
1152 };
1153
1154 void GenCollectedHeap::gc_prologue(bool full) {
1155 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1156
1157 always_do_update_barrier = false;
1158 // Fill TLAB's and such
1159 CollectedHeap::accumulate_statistics_all_tlabs();
1160 ensure_parsability(true); // retire TLABs
1161
1162 // Walk generations
1163 GenGCPrologueClosure blk(full);
1164 generation_iterate(&blk, false); // not old-to-young.
1165 };
1166
1167 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1168 private:
1169 bool _full;
1170 public:
1171 void do_generation(Generation* gen) {
1172 gen->gc_epilogue(_full);
1173 }
1174 GenGCEpilogueClosure(bool full) : _full(full) {};
1175 };
1176
1177 void GenCollectedHeap::gc_epilogue(bool full) {
1178 #ifdef COMPILER2
1179 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1180 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1181 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1182 #endif /* COMPILER2 */
1183
1184 resize_all_tlabs();
1185
1186 GenGCEpilogueClosure blk(full);
1187 generation_iterate(&blk, false); // not old-to-young.
1188
1189 if (!CleanChunkPoolAsync) {
1190 Chunk::clean_chunk_pool();
1191 }
1192
1193 MetaspaceCounters::update_performance_counters();
1194 CompressedClassSpaceCounters::update_performance_counters();
1195
1196 always_do_update_barrier = UseConcMarkSweepGC;
1197 };
1198
1199 #ifndef PRODUCT
1200 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1201 private:
1202 public:
1203 void do_generation(Generation* gen) {
1204 gen->record_spaces_top();
1205 }
1206 };
1207
1208 void GenCollectedHeap::record_gen_tops_before_GC() {
1209 if (ZapUnusedHeapArea) {
1210 GenGCSaveTopsBeforeGCClosure blk;
1211 generation_iterate(&blk, false); // not old-to-young.
1212 }
1213 }
1214 #endif // not PRODUCT
1215
1216 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1217 public:
1218 void do_generation(Generation* gen) {
1219 gen->ensure_parsability();
1220 }
1221 };
1222
1223 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1224 CollectedHeap::ensure_parsability(retire_tlabs);
1225 GenEnsureParsabilityClosure ep_cl;
1226 generation_iterate(&ep_cl, false);
1227 }
1228
1229 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1230 oop obj,
1231 size_t obj_size) {
1232 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1233 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1234 HeapWord* result = NULL;
1235
1236 result = old_gen->expand_and_allocate(obj_size, false);
1237
1238 if (result != NULL) {
1239 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1240 }
1241 return oop(result);
1242 }
1243
1244 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1245 jlong _time; // in ms
1246 jlong _now; // in ms
1247
1248 public:
1249 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1250
1251 jlong time() { return _time; }
1252
1253 void do_generation(Generation* gen) {
1254 _time = MIN2(_time, gen->time_of_last_gc(_now));
1255 }
1256 };
1257
1258 jlong GenCollectedHeap::millis_since_last_gc() {
1259 // We need a monotonically non-decreasing time in ms but
1260 // os::javaTimeMillis() does not guarantee monotonicity.
1261 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1262 GenTimeOfLastGCClosure tolgc_cl(now);
1263 // iterate over generations getting the oldest
1264 // time that a generation was collected
1265 generation_iterate(&tolgc_cl, false);
1266
1267 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1268 // provided the underlying platform provides such a time source
1269 // (and it is bug free). So we still have to guard against getting
1270 // back a time later than 'now'.
1271 jlong retVal = now - tolgc_cl.time();
1272 if (retVal < 0) {
1273 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, retVal);)
1274 return 0;
1275 }
1276 return retVal;
1277 }