1 /*
2 * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc_implementation/shared/collectorCounters.hpp"
31 #include "gc_implementation/shared/gcTrace.hpp"
32 #include "gc_implementation/shared/gcTraceTime.hpp"
33 #include "gc_implementation/shared/vmGCOperations.hpp"
34 #include "gc_interface/collectedHeap.inline.hpp"
35 #include "memory/filemap.hpp"
36 #include "memory/gcLocker.inline.hpp"
37 #include "memory/genCollectedHeap.hpp"
38 #include "memory/genOopClosures.inline.hpp"
39 #include "memory/generationSpec.hpp"
40 #include "memory/resourceArea.hpp"
41 #include "memory/sharedHeap.hpp"
42 #include "memory/space.hpp"
43 #include "oops/oop.inline.hpp"
44 #include "oops/oop.inline2.hpp"
45 #include "runtime/biasedLocking.hpp"
46 #include "runtime/fprofiler.hpp"
47 #include "runtime/handles.hpp"
48 #include "runtime/handles.inline.hpp"
49 #include "runtime/java.hpp"
50 #include "runtime/vmThread.hpp"
51 #include "services/memoryService.hpp"
52 #include "utilities/vmError.hpp"
53 #include "utilities/workgroup.hpp"
54 #include "utilities/macros.hpp"
55 #if INCLUDE_ALL_GCS
56 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
57 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
58 #endif // INCLUDE_ALL_GCS
59
60 GenCollectedHeap* GenCollectedHeap::_gch;
61 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
62
63 // The set of potentially parallel tasks in root scanning.
64 enum GCH_strong_roots_tasks {
65 // We probably want to parallelize both of these internally, but for now...
66 GCH_PS_younger_gens,
67 // Leave this one last.
68 GCH_PS_NumElements
69 };
70
71 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
72 SharedHeap(policy),
73 _rem_set(NULL),
74 _gen_policy(policy),
75 _gen_process_roots_tasks(new SubTasksDone(GCH_PS_NumElements)),
76 _full_collections_completed(0)
77 {
78 if (_gen_process_roots_tasks == NULL ||
79 !_gen_process_roots_tasks->valid()) {
80 vm_exit_during_initialization("Failed necessary allocation.");
81 }
82 assert(policy != NULL, "Sanity check");
83 }
84
85 jint GenCollectedHeap::initialize() {
86 CollectedHeap::pre_initialize();
87
88 int i;
89 _n_gens = gen_policy()->number_of_generations();
90
91 // While there are no constraints in the GC code that HeapWordSize
92 // be any particular value, there are multiple other areas in the
93 // system which believe this to be true (e.g. oop->object_size in some
94 // cases incorrectly returns the size in wordSize units rather than
95 // HeapWordSize).
96 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
97
98 // The heap must be at least as aligned as generations.
99 size_t gen_alignment = Generation::GenGrain;
100
101 _gen_specs = gen_policy()->generations();
102
103 // Make sure the sizes are all aligned.
104 for (i = 0; i < _n_gens; i++) {
105 _gen_specs[i]->align(gen_alignment);
106 }
107
108 // Allocate space for the heap.
109
110 char* heap_address;
111 size_t total_reserved = 0;
112 ReservedSpace heap_rs;
113
114 size_t heap_alignment = collector_policy()->heap_alignment();
115
116 heap_address = allocate(heap_alignment, &total_reserved, &heap_rs);
117
118 if (!heap_rs.is_reserved()) {
119 vm_shutdown_during_initialization(
120 "Could not reserve enough space for object heap");
121 return JNI_ENOMEM;
122 }
123
124 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
125
126 _rem_set = collector_policy()->create_rem_set(reserved_region());
127 set_barrier_set(rem_set()->bs());
128
129 _gch = this;
130
131 for (i = 0; i < _n_gens; i++) {
132 ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
133 _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
134 heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
135 }
136 clear_incremental_collection_failed();
137
138 #if INCLUDE_ALL_GCS
139 // If we are running CMS, create the collector responsible
140 // for collecting the CMS generations.
141 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
142 bool success = create_cms_collector();
143 if (!success) return JNI_ENOMEM;
144 }
145 #endif // INCLUDE_ALL_GCS
146
147 return JNI_OK;
148 }
149
150
151 char* GenCollectedHeap::allocate(size_t alignment,
152 size_t* _total_reserved,
153 ReservedSpace* heap_rs){
154 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
155 "the maximum representable size";
156
157 // Now figure out the total size.
158 size_t total_reserved = 0;
159 const size_t pageSize = UseLargePages ?
160 os::large_page_size() : os::vm_page_size();
161
162 assert(alignment % pageSize == 0, "Must be");
163
164 for (int i = 0; i < _n_gens; i++) {
165 total_reserved += _gen_specs[i]->max_size();
166 if (total_reserved < _gen_specs[i]->max_size()) {
167 vm_exit_during_initialization(overflow_msg);
168 }
169 }
170 assert(total_reserved % alignment == 0,
171 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
172 SIZE_FORMAT, total_reserved, alignment));
173
174 *_total_reserved = total_reserved;
175
176 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
177 return heap_rs->base();
178 }
179
180
181 void GenCollectedHeap::post_initialize() {
182 SharedHeap::post_initialize();
183 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
184 guarantee(policy->is_generation_policy(), "Illegal policy type");
185 assert((get_gen(0)->kind() == Generation::DefNew) ||
186 (get_gen(0)->kind() == Generation::ParNew),
187 "Wrong youngest generation type");
188 DefNewGeneration* def_new_gen = (DefNewGeneration*)get_gen(0);
189
190 Generation* old_gen = get_gen(1);
191 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
192 old_gen->kind() == Generation::MarkSweepCompact,
193 "Wrong generation kind");
194
195 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
196 old_gen->capacity(),
197 def_new_gen->from()->capacity());
198 policy->initialize_gc_policy_counters();
199 }
200
201 void GenCollectedHeap::ref_processing_init() {
202 SharedHeap::ref_processing_init();
203 for (int i = 0; i < _n_gens; i++) {
204 _gens[i]->ref_processor_init();
205 }
206 }
207
208 size_t GenCollectedHeap::capacity() const {
209 size_t res = 0;
210 for (int i = 0; i < _n_gens; i++) {
211 res += _gens[i]->capacity();
212 }
213 return res;
214 }
215
216 size_t GenCollectedHeap::used() const {
217 size_t res = 0;
218 for (int i = 0; i < _n_gens; i++) {
219 res += _gens[i]->used();
220 }
221 return res;
222 }
223
224 // Save the "used_region" for generations level and lower.
225 void GenCollectedHeap::save_used_regions(int level) {
226 assert(level < _n_gens, "Illegal level parameter");
227 for (int i = level; i >= 0; i--) {
228 _gens[i]->save_used_region();
229 }
230 }
231
232 size_t GenCollectedHeap::max_capacity() const {
233 size_t res = 0;
234 for (int i = 0; i < _n_gens; i++) {
235 res += _gens[i]->max_capacity();
236 }
237 return res;
238 }
239
240 // Update the _full_collections_completed counter
241 // at the end of a stop-world full GC.
242 unsigned int GenCollectedHeap::update_full_collections_completed() {
243 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
244 assert(_full_collections_completed <= _total_full_collections,
245 "Can't complete more collections than were started");
246 _full_collections_completed = _total_full_collections;
247 ml.notify_all();
248 return _full_collections_completed;
249 }
250
251 // Update the _full_collections_completed counter, as appropriate,
252 // at the end of a concurrent GC cycle. Note the conditional update
253 // below to allow this method to be called by a concurrent collector
254 // without synchronizing in any manner with the VM thread (which
255 // may already have initiated a STW full collection "concurrently").
256 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
257 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
258 assert((_full_collections_completed <= _total_full_collections) &&
259 (count <= _total_full_collections),
260 "Can't complete more collections than were started");
261 if (count > _full_collections_completed) {
262 _full_collections_completed = count;
263 ml.notify_all();
264 }
265 return _full_collections_completed;
266 }
267
268
269 #ifndef PRODUCT
270 // Override of memory state checking method in CollectedHeap:
271 // Some collectors (CMS for example) can't have badHeapWordVal written
272 // in the first two words of an object. (For instance , in the case of
273 // CMS these words hold state used to synchronize between certain
274 // (concurrent) GC steps and direct allocating mutators.)
275 // The skip_header_HeapWords() method below, allows us to skip
276 // over the requisite number of HeapWord's. Note that (for
277 // generational collectors) this means that those many words are
278 // skipped in each object, irrespective of the generation in which
279 // that object lives. The resultant loss of precision seems to be
280 // harmless and the pain of avoiding that imprecision appears somewhat
281 // higher than we are prepared to pay for such rudimentary debugging
282 // support.
283 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
284 size_t size) {
285 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
286 // We are asked to check a size in HeapWords,
287 // but the memory is mangled in juint words.
288 juint* start = (juint*) (addr + skip_header_HeapWords());
289 juint* end = (juint*) (addr + size);
290 for (juint* slot = start; slot < end; slot += 1) {
291 assert(*slot == badHeapWordVal,
292 "Found non badHeapWordValue in pre-allocation check");
293 }
294 }
295 }
296 #endif
297
298 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
299 bool is_tlab,
300 bool first_only) {
301 HeapWord* res;
302 for (int i = 0; i < _n_gens; i++) {
303 if (_gens[i]->should_allocate(size, is_tlab)) {
304 res = _gens[i]->allocate(size, is_tlab);
305 if (res != NULL) return res;
306 else if (first_only) break;
307 }
308 }
309 // Otherwise...
310 return NULL;
311 }
312
313 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
314 bool* gc_overhead_limit_was_exceeded) {
315 return collector_policy()->mem_allocate_work(size,
316 false /* is_tlab */,
317 gc_overhead_limit_was_exceeded);
318 }
319
320 bool GenCollectedHeap::must_clear_all_soft_refs() {
321 return _gc_cause == GCCause::_last_ditch_collection;
322 }
323
324 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
325 if (!UseConcMarkSweepGC) {
326 return false;
327 }
328
329 switch (cause) {
330 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
331 case GCCause::_java_lang_system_gc:
332 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
333 default: return false;
334 }
335 }
336
337 void GenCollectedHeap::do_collection(bool full,
338 bool clear_all_soft_refs,
339 size_t size,
340 bool is_tlab,
341 int max_level) {
342 bool prepared_for_verification = false;
343 ResourceMark rm;
344 DEBUG_ONLY(Thread* my_thread = Thread::current();)
345
346 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
347 assert(my_thread->is_VM_thread() ||
348 my_thread->is_ConcurrentGC_thread(),
349 "incorrect thread type capability");
350 assert(Heap_lock->is_locked(),
351 "the requesting thread should have the Heap_lock");
352 guarantee(!is_gc_active(), "collection is not reentrant");
353 assert(max_level < n_gens(), "sanity check");
354
355 if (GC_locker::check_active_before_gc()) {
356 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
357 }
358
359 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
360 collector_policy()->should_clear_all_soft_refs();
361
362 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
363
364 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
365
366 print_heap_before_gc();
367
368 {
369 FlagSetting fl(_is_gc_active, true);
370
371 bool complete = full && (max_level == (n_gens()-1));
372 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
373 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
374 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
375 // so we can assume here that the next GC id is what we want.
376 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
377
378 gc_prologue(complete);
379 increment_total_collections(complete);
380
381 size_t gch_prev_used = used();
382
383 int starting_level = 0;
384 if (full) {
385 // Search for the oldest generation which will collect all younger
386 // generations, and start collection loop there.
387 for (int i = max_level; i >= 0; i--) {
388 if (_gens[i]->full_collects_younger_generations()) {
389 starting_level = i;
390 break;
391 }
392 }
393 }
394
395 bool must_restore_marks_for_biased_locking = false;
396
397 int max_level_collected = starting_level;
398 for (int i = starting_level; i <= max_level; i++) {
399 if (_gens[i]->should_collect(full, size, is_tlab)) {
400 if (i == n_gens() - 1) { // a major collection is to happen
401 if (!complete) {
402 // The full_collections increment was missed above.
403 increment_total_full_collections();
404 }
405 pre_full_gc_dump(NULL); // do any pre full gc dumps
406 }
407 // Timer for individual generations. Last argument is false: no CR
408 // FIXME: We should try to start the timing earlier to cover more of the GC pause
409 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
410 // so we can assume here that the next GC id is what we want.
411 GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
412 TraceCollectorStats tcs(_gens[i]->counters());
413 TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
414
415 size_t prev_used = _gens[i]->used();
416 _gens[i]->stat_record()->invocations++;
417 _gens[i]->stat_record()->accumulated_time.start();
418
419 // Must be done anew before each collection because
420 // a previous collection will do mangling and will
421 // change top of some spaces.
422 record_gen_tops_before_GC();
423
424 if (PrintGC && Verbose) {
425 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
426 i,
427 _gens[i]->stat_record()->invocations,
428 size*HeapWordSize);
429 }
430
431 if (VerifyBeforeGC && i >= VerifyGCLevel &&
432 total_collections() >= VerifyGCStartAt) {
433 HandleMark hm; // Discard invalid handles created during verification
434 if (!prepared_for_verification) {
435 prepare_for_verify();
436 prepared_for_verification = true;
437 }
438 Universe::verify(" VerifyBeforeGC:");
439 }
440 COMPILER2_PRESENT(DerivedPointerTable::clear());
441
442 if (!must_restore_marks_for_biased_locking &&
443 _gens[i]->performs_in_place_marking()) {
444 // We perform this mark word preservation work lazily
445 // because it's only at this point that we know whether we
446 // absolutely have to do it; we want to avoid doing it for
447 // scavenge-only collections where it's unnecessary
448 must_restore_marks_for_biased_locking = true;
449 BiasedLocking::preserve_marks();
450 }
451
452 // Do collection work
453 {
454 // Note on ref discovery: For what appear to be historical reasons,
455 // GCH enables and disabled (by enqueing) refs discovery.
456 // In the future this should be moved into the generation's
457 // collect method so that ref discovery and enqueueing concerns
458 // are local to a generation. The collect method could return
459 // an appropriate indication in the case that notification on
460 // the ref lock was needed. This will make the treatment of
461 // weak refs more uniform (and indeed remove such concerns
462 // from GCH). XXX
463
464 HandleMark hm; // Discard invalid handles created during gc
465 save_marks(); // save marks for all gens
466 // We want to discover references, but not process them yet.
467 // This mode is disabled in process_discovered_references if the
468 // generation does some collection work, or in
469 // enqueue_discovered_references if the generation returns
470 // without doing any work.
471 ReferenceProcessor* rp = _gens[i]->ref_processor();
472 // If the discovery of ("weak") refs in this generation is
473 // atomic wrt other collectors in this configuration, we
474 // are guaranteed to have empty discovered ref lists.
475 if (rp->discovery_is_atomic()) {
476 rp->enable_discovery();
477 rp->setup_policy(do_clear_all_soft_refs);
478 } else {
479 // collect() below will enable discovery as appropriate
480 }
481 _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
482 if (!rp->enqueuing_is_done()) {
483 rp->enqueue_discovered_references();
484 } else {
485 rp->set_enqueuing_is_done(false);
486 }
487 rp->verify_no_references_recorded();
488 }
489 max_level_collected = i;
490
491 // Determine if allocation request was met.
492 if (size > 0) {
493 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
494 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
495 size = 0;
496 }
497 }
498 }
499
500 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
501
502 _gens[i]->stat_record()->accumulated_time.stop();
503
504 update_gc_stats(i, full);
505
506 if (VerifyAfterGC && i >= VerifyGCLevel &&
507 total_collections() >= VerifyGCStartAt) {
508 HandleMark hm; // Discard invalid handles created during verification
509 Universe::verify(" VerifyAfterGC:");
510 }
511
512 if (PrintGCDetails) {
513 gclog_or_tty->print(":");
514 _gens[i]->print_heap_change(prev_used);
515 }
516 }
517 }
518
519 // Update "complete" boolean wrt what actually transpired --
520 // for instance, a promotion failure could have led to
521 // a whole heap collection.
522 complete = complete || (max_level_collected == n_gens() - 1);
523
524 if (complete) { // We did a "major" collection
525 // FIXME: See comment at pre_full_gc_dump call
526 post_full_gc_dump(NULL); // do any post full gc dumps
527 }
528
529 if (PrintGCDetails) {
530 print_heap_change(gch_prev_used);
531
532 // Print metaspace info for full GC with PrintGCDetails flag.
533 if (complete) {
534 MetaspaceAux::print_metaspace_change(metadata_prev_used);
535 }
536 }
537
538 for (int j = max_level_collected; j >= 0; j -= 1) {
539 // Adjust generation sizes.
540 _gens[j]->compute_new_size();
541 }
542
543 if (complete) {
544 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
545 ClassLoaderDataGraph::purge();
546 MetaspaceAux::verify_metrics();
547 // Resize the metaspace capacity after full collections
548 MetaspaceGC::compute_new_size();
549 update_full_collections_completed();
550 }
551
552 // Track memory usage and detect low memory after GC finishes
553 MemoryService::track_memory_usage();
554
555 gc_epilogue(complete);
556
557 if (must_restore_marks_for_biased_locking) {
558 BiasedLocking::restore_marks();
559 }
560 }
561
562 print_heap_after_gc();
563
564 #ifdef TRACESPINNING
565 ParallelTaskTerminator::print_termination_counts();
566 #endif
567 }
568
569 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
570 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
571 }
572
573 void GenCollectedHeap::set_par_threads(uint t) {
574 SharedHeap::set_par_threads(t);
575 _gen_process_roots_tasks->set_n_threads(t);
576 }
577
578 void GenCollectedHeap::
579 gen_process_roots(int level,
580 bool younger_gens_as_roots,
581 bool activate_scope,
582 SharedHeap::ScanningOption so,
583 OopsInGenClosure* not_older_gens,
584 OopsInGenClosure* weak_roots,
585 OopsInGenClosure* older_gens,
586 CLDClosure* cld_closure,
587 CLDClosure* weak_cld_closure,
588 CodeBlobClosure* code_closure) {
589
590 // General roots.
591 SharedHeap::process_roots(activate_scope, so,
592 not_older_gens, weak_roots,
593 cld_closure, weak_cld_closure,
594 code_closure);
595
596 if (younger_gens_as_roots) {
597 if (!_gen_process_roots_tasks->is_task_claimed(GCH_PS_younger_gens)) {
598 for (int i = 0; i < level; i++) {
599 not_older_gens->set_generation(_gens[i]);
600 _gens[i]->oop_iterate(not_older_gens);
601 }
602 not_older_gens->reset_generation();
603 }
604 }
605 // When collection is parallel, all threads get to cooperate to do
606 // older-gen scanning.
607 for (int i = level+1; i < _n_gens; i++) {
608 older_gens->set_generation(_gens[i]);
609 rem_set()->younger_refs_iterate(_gens[i], older_gens);
610 older_gens->reset_generation();
611 }
612
613 _gen_process_roots_tasks->all_tasks_completed();
614 }
615
616 void GenCollectedHeap::
617 gen_process_roots(int level,
618 bool younger_gens_as_roots,
619 bool activate_scope,
620 SharedHeap::ScanningOption so,
621 bool only_strong_roots,
622 OopsInGenClosure* not_older_gens,
623 OopsInGenClosure* older_gens,
624 CLDClosure* cld_closure) {
625
626 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
627
628 bool is_moving_collection = false;
629 if (level == 0 || is_adjust_phase) {
630 // young collections are always moving
631 is_moving_collection = true;
632 }
633
634 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
635 CodeBlobClosure* code_closure = &mark_code_closure;
636
637 gen_process_roots(level,
638 younger_gens_as_roots,
639 activate_scope, so,
640 not_older_gens, only_strong_roots ? NULL : not_older_gens,
641 older_gens,
642 cld_closure, only_strong_roots ? NULL : cld_closure,
643 code_closure);
644
645 }
646
647 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
648 SharedHeap::process_weak_roots(root_closure);
649 // "Local" "weak" refs
650 for (int i = 0; i < _n_gens; i++) {
651 _gens[i]->ref_processor()->weak_oops_do(root_closure);
652 }
653 }
654
655 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
656 void GenCollectedHeap:: \
657 oop_since_save_marks_iterate(int level, \
658 OopClosureType* cur, \
659 OopClosureType* older) { \
660 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
661 for (int i = level+1; i < n_gens(); i++) { \
662 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
663 } \
664 }
665
666 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
667
668 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
669
670 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
671 for (int i = level; i < _n_gens; i++) {
672 if (!_gens[i]->no_allocs_since_save_marks()) return false;
673 }
674 return true;
675 }
676
677 bool GenCollectedHeap::supports_inline_contig_alloc() const {
678 return _gens[0]->supports_inline_contig_alloc();
679 }
680
681 HeapWord** GenCollectedHeap::top_addr() const {
682 return _gens[0]->top_addr();
683 }
684
685 HeapWord** GenCollectedHeap::end_addr() const {
686 return _gens[0]->end_addr();
687 }
688
689 // public collection interfaces
690
691 void GenCollectedHeap::collect(GCCause::Cause cause) {
692 if (should_do_concurrent_full_gc(cause)) {
693 #if INCLUDE_ALL_GCS
694 // mostly concurrent full collection
695 collect_mostly_concurrent(cause);
696 #else // INCLUDE_ALL_GCS
697 ShouldNotReachHere();
698 #endif // INCLUDE_ALL_GCS
699 } else if (cause == GCCause::_wb_young_gc) {
700 // minor collection for WhiteBox API
701 collect(cause, 0);
702 } else {
703 #ifdef ASSERT
704 if (cause == GCCause::_scavenge_alot) {
705 // minor collection only
706 collect(cause, 0);
707 } else {
708 // Stop-the-world full collection
709 collect(cause, n_gens() - 1);
710 }
711 #else
712 // Stop-the-world full collection
713 collect(cause, n_gens() - 1);
714 #endif
715 }
716 }
717
718 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
719 // The caller doesn't have the Heap_lock
720 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
721 MutexLocker ml(Heap_lock);
722 collect_locked(cause, max_level);
723 }
724
725 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
726 // The caller has the Heap_lock
727 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
728 collect_locked(cause, n_gens() - 1);
729 }
730
731 // this is the private collection interface
732 // The Heap_lock is expected to be held on entry.
733
734 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
735 // Read the GC count while holding the Heap_lock
736 unsigned int gc_count_before = total_collections();
737 unsigned int full_gc_count_before = total_full_collections();
738 {
739 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
740 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
741 cause, max_level);
742 VMThread::execute(&op);
743 }
744 }
745
746 #if INCLUDE_ALL_GCS
747 bool GenCollectedHeap::create_cms_collector() {
748
749 assert(_gens[1]->kind() == Generation::ConcurrentMarkSweep,
750 "Unexpected generation kinds");
751 // Skip two header words in the block content verification
752 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
753 CMSCollector* collector = new CMSCollector(
754 (ConcurrentMarkSweepGeneration*)_gens[1],
755 _rem_set->as_CardTableRS(),
756 (ConcurrentMarkSweepPolicy*) collector_policy());
757
758 if (collector == NULL || !collector->completed_initialization()) {
759 if (collector) {
760 delete collector; // Be nice in embedded situation
761 }
762 vm_shutdown_during_initialization("Could not create CMS collector");
763 return false;
764 }
765 return true; // success
766 }
767
768 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
769 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
770
771 MutexLocker ml(Heap_lock);
772 // Read the GC counts while holding the Heap_lock
773 unsigned int full_gc_count_before = total_full_collections();
774 unsigned int gc_count_before = total_collections();
775 {
776 MutexUnlocker mu(Heap_lock);
777 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
778 VMThread::execute(&op);
779 }
780 }
781 #endif // INCLUDE_ALL_GCS
782
783 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
784 do_full_collection(clear_all_soft_refs, _n_gens - 1);
785 }
786
787 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
788 int max_level) {
789 int local_max_level;
790 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
791 gc_cause() == GCCause::_gc_locker) {
792 local_max_level = 0;
793 } else {
794 local_max_level = max_level;
795 }
796
797 do_collection(true /* full */,
798 clear_all_soft_refs /* clear_all_soft_refs */,
799 0 /* size */,
800 false /* is_tlab */,
801 local_max_level /* max_level */);
802 // Hack XXX FIX ME !!!
803 // A scavenge may not have been attempted, or may have
804 // been attempted and failed, because the old gen was too full
805 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
806 incremental_collection_will_fail(false /* don't consult_young */)) {
807 if (PrintGCDetails) {
808 gclog_or_tty->print_cr("GC locker: Trying a full collection "
809 "because scavenge failed");
810 }
811 // This time allow the old gen to be collected as well
812 do_collection(true /* full */,
813 clear_all_soft_refs /* clear_all_soft_refs */,
814 0 /* size */,
815 false /* is_tlab */,
816 n_gens() - 1 /* max_level */);
817 }
818 }
819
820 bool GenCollectedHeap::is_in_young(oop p) {
821 bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
822 assert(result == _gens[0]->is_in_reserved(p),
823 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
824 return result;
825 }
826
827 // Returns "TRUE" iff "p" points into the committed areas of the heap.
828 bool GenCollectedHeap::is_in(const void* p) const {
829 #ifndef ASSERT
830 guarantee(VerifyBeforeGC ||
831 VerifyDuringGC ||
832 VerifyBeforeExit ||
833 VerifyDuringStartup ||
834 PrintAssembly ||
835 tty->count() != 0 || // already printing
836 VerifyAfterGC ||
837 VMError::fatal_error_in_progress(), "too expensive");
838
839 #endif
840 // This might be sped up with a cache of the last generation that
841 // answered yes.
842 for (int i = 0; i < _n_gens; i++) {
843 if (_gens[i]->is_in(p)) return true;
844 }
845 // Otherwise...
846 return false;
847 }
848
849 #ifdef ASSERT
850 // Don't implement this by using is_in_young(). This method is used
851 // in some cases to check that is_in_young() is correct.
852 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
853 assert(is_in_reserved(p) || p == NULL,
854 "Does not work if address is non-null and outside of the heap");
855 return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
856 }
857 #endif
858
859 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
860 for (int i = 0; i < _n_gens; i++) {
861 _gens[i]->oop_iterate(cl);
862 }
863 }
864
865 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
866 for (int i = 0; i < _n_gens; i++) {
867 _gens[i]->object_iterate(cl);
868 }
869 }
870
871 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
872 for (int i = 0; i < _n_gens; i++) {
873 _gens[i]->safe_object_iterate(cl);
874 }
875 }
876
877 Space* GenCollectedHeap::space_containing(const void* addr) const {
878 for (int i = 0; i < _n_gens; i++) {
879 Space* res = _gens[i]->space_containing(addr);
880 if (res != NULL) return res;
881 }
882 // Otherwise...
883 assert(false, "Could not find containing space");
884 return NULL;
885 }
886
887
888 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
889 assert(is_in_reserved(addr), "block_start of address outside of heap");
890 for (int i = 0; i < _n_gens; i++) {
891 if (_gens[i]->is_in_reserved(addr)) {
892 assert(_gens[i]->is_in(addr),
893 "addr should be in allocated part of generation");
894 return _gens[i]->block_start(addr);
895 }
896 }
897 assert(false, "Some generation should contain the address");
898 return NULL;
899 }
900
901 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
902 assert(is_in_reserved(addr), "block_size of address outside of heap");
903 for (int i = 0; i < _n_gens; i++) {
904 if (_gens[i]->is_in_reserved(addr)) {
905 assert(_gens[i]->is_in(addr),
906 "addr should be in allocated part of generation");
907 return _gens[i]->block_size(addr);
908 }
909 }
910 assert(false, "Some generation should contain the address");
911 return 0;
912 }
913
914 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
915 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
916 assert(block_start(addr) == addr, "addr must be a block start");
917 for (int i = 0; i < _n_gens; i++) {
918 if (_gens[i]->is_in_reserved(addr)) {
919 return _gens[i]->block_is_obj(addr);
920 }
921 }
922 assert(false, "Some generation should contain the address");
923 return false;
924 }
925
926 bool GenCollectedHeap::supports_tlab_allocation() const {
927 for (int i = 0; i < _n_gens; i += 1) {
928 if (_gens[i]->supports_tlab_allocation()) {
929 return true;
930 }
931 }
932 return false;
933 }
934
935 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
936 size_t result = 0;
937 for (int i = 0; i < _n_gens; i += 1) {
938 if (_gens[i]->supports_tlab_allocation()) {
939 result += _gens[i]->tlab_capacity();
940 }
941 }
942 return result;
943 }
944
945 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
946 size_t result = 0;
947 for (int i = 0; i < _n_gens; i += 1) {
948 if (_gens[i]->supports_tlab_allocation()) {
949 result += _gens[i]->tlab_used();
950 }
951 }
952 return result;
953 }
954
955 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
956 size_t result = 0;
957 for (int i = 0; i < _n_gens; i += 1) {
958 if (_gens[i]->supports_tlab_allocation()) {
959 result += _gens[i]->unsafe_max_tlab_alloc();
960 }
961 }
962 return result;
963 }
964
965 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
966 bool gc_overhead_limit_was_exceeded;
967 return collector_policy()->mem_allocate_work(size /* size */,
968 true /* is_tlab */,
969 &gc_overhead_limit_was_exceeded);
970 }
971
972 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
973 // from the list headed by "*prev_ptr".
974 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
975 bool first = true;
976 size_t min_size = 0; // "first" makes this conceptually infinite.
977 ScratchBlock **smallest_ptr, *smallest;
978 ScratchBlock *cur = *prev_ptr;
979 while (cur) {
980 assert(*prev_ptr == cur, "just checking");
981 if (first || cur->num_words < min_size) {
982 smallest_ptr = prev_ptr;
983 smallest = cur;
984 min_size = smallest->num_words;
985 first = false;
986 }
987 prev_ptr = &cur->next;
988 cur = cur->next;
989 }
990 smallest = *smallest_ptr;
991 *smallest_ptr = smallest->next;
992 return smallest;
993 }
994
995 // Sort the scratch block list headed by res into decreasing size order,
996 // and set "res" to the result.
997 static void sort_scratch_list(ScratchBlock*& list) {
998 ScratchBlock* sorted = NULL;
999 ScratchBlock* unsorted = list;
1000 while (unsorted) {
1001 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1002 smallest->next = sorted;
1003 sorted = smallest;
1004 }
1005 list = sorted;
1006 }
1007
1008 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1009 size_t max_alloc_words) {
1010 ScratchBlock* res = NULL;
1011 for (int i = 0; i < _n_gens; i++) {
1012 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1013 }
1014 sort_scratch_list(res);
1015 return res;
1016 }
1017
1018 void GenCollectedHeap::release_scratch() {
1019 for (int i = 0; i < _n_gens; i++) {
1020 _gens[i]->reset_scratch();
1021 }
1022 }
1023
1024 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1025 void do_generation(Generation* gen) {
1026 gen->prepare_for_verify();
1027 }
1028 };
1029
1030 void GenCollectedHeap::prepare_for_verify() {
1031 ensure_parsability(false); // no need to retire TLABs
1032 GenPrepareForVerifyClosure blk;
1033 generation_iterate(&blk, false);
1034 }
1035
1036
1037 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1038 bool old_to_young) {
1039 if (old_to_young) {
1040 for (int i = _n_gens-1; i >= 0; i--) {
1041 cl->do_generation(_gens[i]);
1042 }
1043 } else {
1044 for (int i = 0; i < _n_gens; i++) {
1045 cl->do_generation(_gens[i]);
1046 }
1047 }
1048 }
1049
1050 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1051 for (int i = 0; i < _n_gens; i++) {
1052 _gens[i]->space_iterate(cl, true);
1053 }
1054 }
1055
1056 bool GenCollectedHeap::is_maximal_no_gc() const {
1057 for (int i = 0; i < _n_gens; i++) {
1058 if (!_gens[i]->is_maximal_no_gc()) {
1059 return false;
1060 }
1061 }
1062 return true;
1063 }
1064
1065 void GenCollectedHeap::save_marks() {
1066 for (int i = 0; i < _n_gens; i++) {
1067 _gens[i]->save_marks();
1068 }
1069 }
1070
1071 GenCollectedHeap* GenCollectedHeap::heap() {
1072 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1073 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1074 return _gch;
1075 }
1076
1077
1078 void GenCollectedHeap::prepare_for_compaction() {
1079 guarantee(_n_gens = 2, "Wrong number of generations");
1080 Generation* old_gen = _gens[1];
1081 // Start by compacting into same gen.
1082 CompactPoint cp(old_gen);
1083 old_gen->prepare_for_compaction(&cp);
1084 Generation* young_gen = _gens[0];
1085 young_gen->prepare_for_compaction(&cp);
1086 }
1087
1088 GCStats* GenCollectedHeap::gc_stats(int level) const {
1089 return _gens[level]->gc_stats();
1090 }
1091
1092 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1093 for (int i = _n_gens-1; i >= 0; i--) {
1094 Generation* g = _gens[i];
1095 if (!silent) {
1096 gclog_or_tty->print("%s", g->name());
1097 gclog_or_tty->print(" ");
1098 }
1099 g->verify();
1100 }
1101 if (!silent) {
1102 gclog_or_tty->print("remset ");
1103 }
1104 rem_set()->verify();
1105 }
1106
1107 void GenCollectedHeap::print_on(outputStream* st) const {
1108 for (int i = 0; i < _n_gens; i++) {
1109 _gens[i]->print_on(st);
1110 }
1111 MetaspaceAux::print_on(st);
1112 }
1113
1114 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1115 if (workers() != NULL) {
1116 workers()->threads_do(tc);
1117 }
1118 #if INCLUDE_ALL_GCS
1119 if (UseConcMarkSweepGC) {
1120 ConcurrentMarkSweepThread::threads_do(tc);
1121 }
1122 #endif // INCLUDE_ALL_GCS
1123 }
1124
1125 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1126 #if INCLUDE_ALL_GCS
1127 if (UseConcMarkSweepGC) {
1128 workers()->print_worker_threads_on(st);
1129 ConcurrentMarkSweepThread::print_all_on(st);
1130 }
1131 #endif // INCLUDE_ALL_GCS
1132 }
1133
1134 void GenCollectedHeap::print_on_error(outputStream* st) const {
1135 this->CollectedHeap::print_on_error(st);
1136
1137 #if INCLUDE_ALL_GCS
1138 if (UseConcMarkSweepGC) {
1139 st->cr();
1140 CMSCollector::print_on_error(st);
1141 }
1142 #endif // INCLUDE_ALL_GCS
1143 }
1144
1145 void GenCollectedHeap::print_tracing_info() const {
1146 if (TraceYoungGenTime) {
1147 get_gen(0)->print_summary_info();
1148 }
1149 if (TraceOldGenTime) {
1150 get_gen(1)->print_summary_info();
1151 }
1152 }
1153
1154 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1155 if (PrintGCDetails && Verbose) {
1156 gclog_or_tty->print(" " SIZE_FORMAT
1157 "->" SIZE_FORMAT
1158 "(" SIZE_FORMAT ")",
1159 prev_used, used(), capacity());
1160 } else {
1161 gclog_or_tty->print(" " SIZE_FORMAT "K"
1162 "->" SIZE_FORMAT "K"
1163 "(" SIZE_FORMAT "K)",
1164 prev_used / K, used() / K, capacity() / K);
1165 }
1166 }
1167
1168 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1169 private:
1170 bool _full;
1171 public:
1172 void do_generation(Generation* gen) {
1173 gen->gc_prologue(_full);
1174 }
1175 GenGCPrologueClosure(bool full) : _full(full) {};
1176 };
1177
1178 void GenCollectedHeap::gc_prologue(bool full) {
1179 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1180
1181 always_do_update_barrier = false;
1182 // Fill TLAB's and such
1183 CollectedHeap::accumulate_statistics_all_tlabs();
1184 ensure_parsability(true); // retire TLABs
1185
1186 // Walk generations
1187 GenGCPrologueClosure blk(full);
1188 generation_iterate(&blk, false); // not old-to-young.
1189 };
1190
1191 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1192 private:
1193 bool _full;
1194 public:
1195 void do_generation(Generation* gen) {
1196 gen->gc_epilogue(_full);
1197 }
1198 GenGCEpilogueClosure(bool full) : _full(full) {};
1199 };
1200
1201 void GenCollectedHeap::gc_epilogue(bool full) {
1202 #ifdef COMPILER2
1203 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1204 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1205 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1206 #endif /* COMPILER2 */
1207
1208 resize_all_tlabs();
1209
1210 GenGCEpilogueClosure blk(full);
1211 generation_iterate(&blk, false); // not old-to-young.
1212
1213 if (!CleanChunkPoolAsync) {
1214 Chunk::clean_chunk_pool();
1215 }
1216
1217 MetaspaceCounters::update_performance_counters();
1218 CompressedClassSpaceCounters::update_performance_counters();
1219
1220 always_do_update_barrier = UseConcMarkSweepGC;
1221 };
1222
1223 #ifndef PRODUCT
1224 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1225 private:
1226 public:
1227 void do_generation(Generation* gen) {
1228 gen->record_spaces_top();
1229 }
1230 };
1231
1232 void GenCollectedHeap::record_gen_tops_before_GC() {
1233 if (ZapUnusedHeapArea) {
1234 GenGCSaveTopsBeforeGCClosure blk;
1235 generation_iterate(&blk, false); // not old-to-young.
1236 }
1237 }
1238 #endif // not PRODUCT
1239
1240 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1241 public:
1242 void do_generation(Generation* gen) {
1243 gen->ensure_parsability();
1244 }
1245 };
1246
1247 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1248 CollectedHeap::ensure_parsability(retire_tlabs);
1249 GenEnsureParsabilityClosure ep_cl;
1250 generation_iterate(&ep_cl, false);
1251 }
1252
1253 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1254 oop obj,
1255 size_t obj_size) {
1256 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1257 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1258 HeapWord* result = NULL;
1259
1260 result = old_gen->expand_and_allocate(obj_size, false);
1261
1262 if (result != NULL) {
1263 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1264 }
1265 return oop(result);
1266 }
1267
1268 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1269 jlong _time; // in ms
1270 jlong _now; // in ms
1271
1272 public:
1273 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1274
1275 jlong time() { return _time; }
1276
1277 void do_generation(Generation* gen) {
1278 _time = MIN2(_time, gen->time_of_last_gc(_now));
1279 }
1280 };
1281
1282 jlong GenCollectedHeap::millis_since_last_gc() {
1283 // We need a monotonically non-decreasing time in ms but
1284 // os::javaTimeMillis() does not guarantee monotonicity.
1285 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1286 GenTimeOfLastGCClosure tolgc_cl(now);
1287 // iterate over generations getting the oldest
1288 // time that a generation was collected
1289 generation_iterate(&tolgc_cl, false);
1290
1291 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1292 // provided the underlying platform provides such a time source
1293 // (and it is bug free). So we still have to guard against getting
1294 // back a time later than 'now'.
1295 jlong retVal = now - tolgc_cl.time();
1296 if (retVal < 0) {
1297 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1298 return 0;
1299 }
1300 return retVal;
1301 }