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 return UseConcMarkSweepGC &&
326 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
327 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
328 }
329
330 void GenCollectedHeap::do_collection(bool full,
331 bool clear_all_soft_refs,
332 size_t size,
333 bool is_tlab,
334 int max_level) {
335 bool prepared_for_verification = false;
336 ResourceMark rm;
337 DEBUG_ONLY(Thread* my_thread = Thread::current();)
338
339 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
340 assert(my_thread->is_VM_thread() ||
341 my_thread->is_ConcurrentGC_thread(),
342 "incorrect thread type capability");
343 assert(Heap_lock->is_locked(),
344 "the requesting thread should have the Heap_lock");
345 guarantee(!is_gc_active(), "collection is not reentrant");
346 assert(max_level < n_gens(), "sanity check");
347
348 if (GC_locker::check_active_before_gc()) {
349 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
350 }
351
352 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
353 collector_policy()->should_clear_all_soft_refs();
354
355 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
356
357 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
358
359 print_heap_before_gc();
360
361 {
362 FlagSetting fl(_is_gc_active, true);
363
364 bool complete = full && (max_level == (n_gens()-1));
365 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
366 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
367 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
368 // so we can assume here that the next GC id is what we want.
369 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
370
371 gc_prologue(complete);
372 increment_total_collections(complete);
373
374 size_t gch_prev_used = used();
375
376 int starting_level = 0;
377 if (full) {
378 // Search for the oldest generation which will collect all younger
379 // generations, and start collection loop there.
380 for (int i = max_level; i >= 0; i--) {
381 if (_gens[i]->full_collects_younger_generations()) {
382 starting_level = i;
383 break;
384 }
385 }
386 }
387
388 bool must_restore_marks_for_biased_locking = false;
389
390 int max_level_collected = starting_level;
391 for (int i = starting_level; i <= max_level; i++) {
392 if (_gens[i]->should_collect(full, size, is_tlab)) {
393 if (i == n_gens() - 1) { // a major collection is to happen
394 if (!complete) {
395 // The full_collections increment was missed above.
396 increment_total_full_collections();
397 }
398 pre_full_gc_dump(NULL); // do any pre full gc dumps
399 }
400 // Timer for individual generations. Last argument is false: no CR
401 // FIXME: We should try to start the timing earlier to cover more of the GC pause
402 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
403 // so we can assume here that the next GC id is what we want.
404 GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
405 TraceCollectorStats tcs(_gens[i]->counters());
406 TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
407
408 size_t prev_used = _gens[i]->used();
409 _gens[i]->stat_record()->invocations++;
410 _gens[i]->stat_record()->accumulated_time.start();
411
412 // Must be done anew before each collection because
413 // a previous collection will do mangling and will
414 // change top of some spaces.
415 record_gen_tops_before_GC();
416
417 if (PrintGC && Verbose) {
418 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
419 i,
420 _gens[i]->stat_record()->invocations,
421 size*HeapWordSize);
422 }
423
424 if (VerifyBeforeGC && i >= VerifyGCLevel &&
425 total_collections() >= VerifyGCStartAt) {
426 HandleMark hm; // Discard invalid handles created during verification
427 if (!prepared_for_verification) {
428 prepare_for_verify();
429 prepared_for_verification = true;
430 }
431 Universe::verify(" VerifyBeforeGC:");
432 }
433 COMPILER2_PRESENT(DerivedPointerTable::clear());
434
435 if (!must_restore_marks_for_biased_locking &&
436 _gens[i]->performs_in_place_marking()) {
437 // We perform this mark word preservation work lazily
438 // because it's only at this point that we know whether we
439 // absolutely have to do it; we want to avoid doing it for
440 // scavenge-only collections where it's unnecessary
441 must_restore_marks_for_biased_locking = true;
442 BiasedLocking::preserve_marks();
443 }
444
445 // Do collection work
446 {
447 // Note on ref discovery: For what appear to be historical reasons,
448 // GCH enables and disabled (by enqueing) refs discovery.
449 // In the future this should be moved into the generation's
450 // collect method so that ref discovery and enqueueing concerns
451 // are local to a generation. The collect method could return
452 // an appropriate indication in the case that notification on
453 // the ref lock was needed. This will make the treatment of
454 // weak refs more uniform (and indeed remove such concerns
455 // from GCH). XXX
456
457 HandleMark hm; // Discard invalid handles created during gc
458 save_marks(); // save marks for all gens
459 // We want to discover references, but not process them yet.
460 // This mode is disabled in process_discovered_references if the
461 // generation does some collection work, or in
462 // enqueue_discovered_references if the generation returns
463 // without doing any work.
464 ReferenceProcessor* rp = _gens[i]->ref_processor();
465 // If the discovery of ("weak") refs in this generation is
466 // atomic wrt other collectors in this configuration, we
467 // are guaranteed to have empty discovered ref lists.
468 if (rp->discovery_is_atomic()) {
469 rp->enable_discovery();
470 rp->setup_policy(do_clear_all_soft_refs);
471 } else {
472 // collect() below will enable discovery as appropriate
473 }
474 _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
475 if (!rp->enqueuing_is_done()) {
476 rp->enqueue_discovered_references();
477 } else {
478 rp->set_enqueuing_is_done(false);
479 }
480 rp->verify_no_references_recorded();
481 }
482 max_level_collected = i;
483
484 // Determine if allocation request was met.
485 if (size > 0) {
486 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
487 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
488 size = 0;
489 }
490 }
491 }
492
493 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
494
495 _gens[i]->stat_record()->accumulated_time.stop();
496
497 update_gc_stats(i, full);
498
499 if (VerifyAfterGC && i >= VerifyGCLevel &&
500 total_collections() >= VerifyGCStartAt) {
501 HandleMark hm; // Discard invalid handles created during verification
502 Universe::verify(" VerifyAfterGC:");
503 }
504
505 if (PrintGCDetails) {
506 gclog_or_tty->print(":");
507 _gens[i]->print_heap_change(prev_used);
508 }
509 }
510 }
511
512 // Update "complete" boolean wrt what actually transpired --
513 // for instance, a promotion failure could have led to
514 // a whole heap collection.
515 complete = complete || (max_level_collected == n_gens() - 1);
516
517 if (complete) { // We did a "major" collection
518 // FIXME: See comment at pre_full_gc_dump call
519 post_full_gc_dump(NULL); // do any post full gc dumps
520 }
521
522 if (PrintGCDetails) {
523 print_heap_change(gch_prev_used);
524
525 // Print metaspace info for full GC with PrintGCDetails flag.
526 if (complete) {
527 MetaspaceAux::print_metaspace_change(metadata_prev_used);
528 }
529 }
530
531 for (int j = max_level_collected; j >= 0; j -= 1) {
532 // Adjust generation sizes.
533 _gens[j]->compute_new_size();
534 }
535
536 if (complete) {
537 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
538 ClassLoaderDataGraph::purge();
539 MetaspaceAux::verify_metrics();
540 // Resize the metaspace capacity after full collections
541 MetaspaceGC::compute_new_size();
542 update_full_collections_completed();
543 }
544
545 // Track memory usage and detect low memory after GC finishes
546 MemoryService::track_memory_usage();
547
548 gc_epilogue(complete);
549
550 if (must_restore_marks_for_biased_locking) {
551 BiasedLocking::restore_marks();
552 }
553 }
554
555 print_heap_after_gc();
556
557 #ifdef TRACESPINNING
558 ParallelTaskTerminator::print_termination_counts();
559 #endif
560 }
561
562 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
563 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
564 }
565
566 void GenCollectedHeap::set_par_threads(uint t) {
567 SharedHeap::set_par_threads(t);
568 _gen_process_roots_tasks->set_n_threads(t);
569 }
570
571 void GenCollectedHeap::
572 gen_process_roots(int level,
573 bool younger_gens_as_roots,
574 bool activate_scope,
575 SharedHeap::ScanningOption so,
576 OopsInGenClosure* not_older_gens,
577 OopsInGenClosure* weak_roots,
578 OopsInGenClosure* older_gens,
579 CLDClosure* cld_closure,
580 CLDClosure* weak_cld_closure,
581 CodeBlobClosure* code_closure) {
582
583 // General roots.
584 SharedHeap::process_roots(activate_scope, so,
585 not_older_gens, weak_roots,
586 cld_closure, weak_cld_closure,
587 code_closure);
588
589 if (younger_gens_as_roots) {
590 if (!_gen_process_roots_tasks->is_task_claimed(GCH_PS_younger_gens)) {
591 for (int i = 0; i < level; i++) {
592 not_older_gens->set_generation(_gens[i]);
593 _gens[i]->oop_iterate(not_older_gens);
594 }
595 not_older_gens->reset_generation();
596 }
597 }
598 // When collection is parallel, all threads get to cooperate to do
599 // older-gen scanning.
600 for (int i = level+1; i < _n_gens; i++) {
601 older_gens->set_generation(_gens[i]);
602 rem_set()->younger_refs_iterate(_gens[i], older_gens);
603 older_gens->reset_generation();
604 }
605
606 _gen_process_roots_tasks->all_tasks_completed();
607 }
608
609 void GenCollectedHeap::
610 gen_process_roots(int level,
611 bool younger_gens_as_roots,
612 bool activate_scope,
613 SharedHeap::ScanningOption so,
614 bool only_strong_roots,
615 OopsInGenClosure* not_older_gens,
616 OopsInGenClosure* older_gens,
617 CLDClosure* cld_closure) {
618
619 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
620
621 bool is_moving_collection = false;
622 if (level == 0 || is_adjust_phase) {
623 // young collections are always moving
624 is_moving_collection = true;
625 }
626
627 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
628 CodeBlobClosure* code_closure = &mark_code_closure;
629
630 gen_process_roots(level,
631 younger_gens_as_roots,
632 activate_scope, so,
633 not_older_gens, only_strong_roots ? NULL : not_older_gens,
634 older_gens,
635 cld_closure, only_strong_roots ? NULL : cld_closure,
636 code_closure);
637
638 }
639
640 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
641 SharedHeap::process_weak_roots(root_closure);
642 // "Local" "weak" refs
643 for (int i = 0; i < _n_gens; i++) {
644 _gens[i]->ref_processor()->weak_oops_do(root_closure);
645 }
646 }
647
648 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
649 void GenCollectedHeap:: \
650 oop_since_save_marks_iterate(int level, \
651 OopClosureType* cur, \
652 OopClosureType* older) { \
653 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
654 for (int i = level+1; i < n_gens(); i++) { \
655 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
656 } \
657 }
658
659 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
660
661 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
662
663 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
664 for (int i = level; i < _n_gens; i++) {
665 if (!_gens[i]->no_allocs_since_save_marks()) return false;
666 }
667 return true;
668 }
669
670 bool GenCollectedHeap::supports_inline_contig_alloc() const {
671 return _gens[0]->supports_inline_contig_alloc();
672 }
673
674 HeapWord** GenCollectedHeap::top_addr() const {
675 return _gens[0]->top_addr();
676 }
677
678 HeapWord** GenCollectedHeap::end_addr() const {
679 return _gens[0]->end_addr();
680 }
681
682 // public collection interfaces
683
684 void GenCollectedHeap::collect(GCCause::Cause cause) {
685 if (should_do_concurrent_full_gc(cause)) {
686 #if INCLUDE_ALL_GCS
687 // mostly concurrent full collection
688 collect_mostly_concurrent(cause);
689 #else // INCLUDE_ALL_GCS
690 ShouldNotReachHere();
691 #endif // INCLUDE_ALL_GCS
692 } else if (cause == GCCause::_wb_young_gc) {
693 // minor collection for WhiteBox API
694 collect(cause, 0);
695 } else {
696 #ifdef ASSERT
697 if (cause == GCCause::_scavenge_alot) {
698 // minor collection only
699 collect(cause, 0);
700 } else {
701 // Stop-the-world full collection
702 collect(cause, n_gens() - 1);
703 }
704 #else
705 // Stop-the-world full collection
706 collect(cause, n_gens() - 1);
707 #endif
708 }
709 }
710
711 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
712 // The caller doesn't have the Heap_lock
713 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
714 MutexLocker ml(Heap_lock);
715 collect_locked(cause, max_level);
716 }
717
718 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
719 // The caller has the Heap_lock
720 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
721 collect_locked(cause, n_gens() - 1);
722 }
723
724 // this is the private collection interface
725 // The Heap_lock is expected to be held on entry.
726
727 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
728 // Read the GC count while holding the Heap_lock
729 unsigned int gc_count_before = total_collections();
730 unsigned int full_gc_count_before = total_full_collections();
731 {
732 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
733 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
734 cause, max_level);
735 VMThread::execute(&op);
736 }
737 }
738
739 #if INCLUDE_ALL_GCS
740 bool GenCollectedHeap::create_cms_collector() {
741
742 assert(_gens[1]->kind() == Generation::ConcurrentMarkSweep,
743 "Unexpected generation kinds");
744 // Skip two header words in the block content verification
745 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
746 CMSCollector* collector = new CMSCollector(
747 (ConcurrentMarkSweepGeneration*)_gens[1],
748 _rem_set->as_CardTableRS(),
749 (ConcurrentMarkSweepPolicy*) collector_policy());
750
751 if (collector == NULL || !collector->completed_initialization()) {
752 if (collector) {
753 delete collector; // Be nice in embedded situation
754 }
755 vm_shutdown_during_initialization("Could not create CMS collector");
756 return false;
757 }
758 return true; // success
759 }
760
761 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
762 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
763
764 MutexLocker ml(Heap_lock);
765 // Read the GC counts while holding the Heap_lock
766 unsigned int full_gc_count_before = total_full_collections();
767 unsigned int gc_count_before = total_collections();
768 {
769 MutexUnlocker mu(Heap_lock);
770 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
771 VMThread::execute(&op);
772 }
773 }
774 #endif // INCLUDE_ALL_GCS
775
776 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
777 do_full_collection(clear_all_soft_refs, _n_gens - 1);
778 }
779
780 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
781 int max_level) {
782 int local_max_level;
783 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
784 gc_cause() == GCCause::_gc_locker) {
785 local_max_level = 0;
786 } else {
787 local_max_level = max_level;
788 }
789
790 do_collection(true /* full */,
791 clear_all_soft_refs /* clear_all_soft_refs */,
792 0 /* size */,
793 false /* is_tlab */,
794 local_max_level /* max_level */);
795 // Hack XXX FIX ME !!!
796 // A scavenge may not have been attempted, or may have
797 // been attempted and failed, because the old gen was too full
798 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
799 incremental_collection_will_fail(false /* don't consult_young */)) {
800 if (PrintGCDetails) {
801 gclog_or_tty->print_cr("GC locker: Trying a full collection "
802 "because scavenge failed");
803 }
804 // This time allow the old gen to be collected as well
805 do_collection(true /* full */,
806 clear_all_soft_refs /* clear_all_soft_refs */,
807 0 /* size */,
808 false /* is_tlab */,
809 n_gens() - 1 /* max_level */);
810 }
811 }
812
813 bool GenCollectedHeap::is_in_young(oop p) {
814 bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
815 assert(result == _gens[0]->is_in_reserved(p),
816 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
817 return result;
818 }
819
820 // Returns "TRUE" iff "p" points into the committed areas of the heap.
821 bool GenCollectedHeap::is_in(const void* p) const {
822 #ifndef ASSERT
823 guarantee(VerifyBeforeGC ||
824 VerifyDuringGC ||
825 VerifyBeforeExit ||
826 VerifyDuringStartup ||
827 PrintAssembly ||
828 tty->count() != 0 || // already printing
829 VerifyAfterGC ||
830 VMError::fatal_error_in_progress(), "too expensive");
831
832 #endif
833 // This might be sped up with a cache of the last generation that
834 // answered yes.
835 for (int i = 0; i < _n_gens; i++) {
836 if (_gens[i]->is_in(p)) return true;
837 }
838 // Otherwise...
839 return false;
840 }
841
842 #ifdef ASSERT
843 // Don't implement this by using is_in_young(). This method is used
844 // in some cases to check that is_in_young() is correct.
845 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
846 assert(is_in_reserved(p) || p == NULL,
847 "Does not work if address is non-null and outside of the heap");
848 return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
849 }
850 #endif
851
852 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
853 for (int i = 0; i < _n_gens; i++) {
854 _gens[i]->oop_iterate(cl);
855 }
856 }
857
858 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
859 for (int i = 0; i < _n_gens; i++) {
860 _gens[i]->object_iterate(cl);
861 }
862 }
863
864 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
865 for (int i = 0; i < _n_gens; i++) {
866 _gens[i]->safe_object_iterate(cl);
867 }
868 }
869
870 Space* GenCollectedHeap::space_containing(const void* addr) const {
871 for (int i = 0; i < _n_gens; i++) {
872 Space* res = _gens[i]->space_containing(addr);
873 if (res != NULL) return res;
874 }
875 // Otherwise...
876 assert(false, "Could not find containing space");
877 return NULL;
878 }
879
880
881 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
882 assert(is_in_reserved(addr), "block_start of address outside of heap");
883 for (int i = 0; i < _n_gens; i++) {
884 if (_gens[i]->is_in_reserved(addr)) {
885 assert(_gens[i]->is_in(addr),
886 "addr should be in allocated part of generation");
887 return _gens[i]->block_start(addr);
888 }
889 }
890 assert(false, "Some generation should contain the address");
891 return NULL;
892 }
893
894 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
895 assert(is_in_reserved(addr), "block_size of address outside of heap");
896 for (int i = 0; i < _n_gens; i++) {
897 if (_gens[i]->is_in_reserved(addr)) {
898 assert(_gens[i]->is_in(addr),
899 "addr should be in allocated part of generation");
900 return _gens[i]->block_size(addr);
901 }
902 }
903 assert(false, "Some generation should contain the address");
904 return 0;
905 }
906
907 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
908 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
909 assert(block_start(addr) == addr, "addr must be a block start");
910 for (int i = 0; i < _n_gens; i++) {
911 if (_gens[i]->is_in_reserved(addr)) {
912 return _gens[i]->block_is_obj(addr);
913 }
914 }
915 assert(false, "Some generation should contain the address");
916 return false;
917 }
918
919 bool GenCollectedHeap::supports_tlab_allocation() const {
920 for (int i = 0; i < _n_gens; i += 1) {
921 if (_gens[i]->supports_tlab_allocation()) {
922 return true;
923 }
924 }
925 return false;
926 }
927
928 size_t GenCollectedHeap::tlab_capacity(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]->tlab_capacity();
933 }
934 }
935 return result;
936 }
937
938 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
939 size_t result = 0;
940 for (int i = 0; i < _n_gens; i += 1) {
941 if (_gens[i]->supports_tlab_allocation()) {
942 result += _gens[i]->tlab_used();
943 }
944 }
945 return result;
946 }
947
948 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
949 size_t result = 0;
950 for (int i = 0; i < _n_gens; i += 1) {
951 if (_gens[i]->supports_tlab_allocation()) {
952 result += _gens[i]->unsafe_max_tlab_alloc();
953 }
954 }
955 return result;
956 }
957
958 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
959 bool gc_overhead_limit_was_exceeded;
960 return collector_policy()->mem_allocate_work(size /* size */,
961 true /* is_tlab */,
962 &gc_overhead_limit_was_exceeded);
963 }
964
965 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
966 // from the list headed by "*prev_ptr".
967 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
968 bool first = true;
969 size_t min_size = 0; // "first" makes this conceptually infinite.
970 ScratchBlock **smallest_ptr, *smallest;
971 ScratchBlock *cur = *prev_ptr;
972 while (cur) {
973 assert(*prev_ptr == cur, "just checking");
974 if (first || cur->num_words < min_size) {
975 smallest_ptr = prev_ptr;
976 smallest = cur;
977 min_size = smallest->num_words;
978 first = false;
979 }
980 prev_ptr = &cur->next;
981 cur = cur->next;
982 }
983 smallest = *smallest_ptr;
984 *smallest_ptr = smallest->next;
985 return smallest;
986 }
987
988 // Sort the scratch block list headed by res into decreasing size order,
989 // and set "res" to the result.
990 static void sort_scratch_list(ScratchBlock*& list) {
991 ScratchBlock* sorted = NULL;
992 ScratchBlock* unsorted = list;
993 while (unsorted) {
994 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
995 smallest->next = sorted;
996 sorted = smallest;
997 }
998 list = sorted;
999 }
1000
1001 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1002 size_t max_alloc_words) {
1003 ScratchBlock* res = NULL;
1004 for (int i = 0; i < _n_gens; i++) {
1005 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1006 }
1007 sort_scratch_list(res);
1008 return res;
1009 }
1010
1011 void GenCollectedHeap::release_scratch() {
1012 for (int i = 0; i < _n_gens; i++) {
1013 _gens[i]->reset_scratch();
1014 }
1015 }
1016
1017 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1018 void do_generation(Generation* gen) {
1019 gen->prepare_for_verify();
1020 }
1021 };
1022
1023 void GenCollectedHeap::prepare_for_verify() {
1024 ensure_parsability(false); // no need to retire TLABs
1025 GenPrepareForVerifyClosure blk;
1026 generation_iterate(&blk, false);
1027 }
1028
1029
1030 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1031 bool old_to_young) {
1032 if (old_to_young) {
1033 for (int i = _n_gens-1; i >= 0; i--) {
1034 cl->do_generation(_gens[i]);
1035 }
1036 } else {
1037 for (int i = 0; i < _n_gens; i++) {
1038 cl->do_generation(_gens[i]);
1039 }
1040 }
1041 }
1042
1043 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1044 for (int i = 0; i < _n_gens; i++) {
1045 _gens[i]->space_iterate(cl, true);
1046 }
1047 }
1048
1049 bool GenCollectedHeap::is_maximal_no_gc() const {
1050 for (int i = 0; i < _n_gens; i++) {
1051 if (!_gens[i]->is_maximal_no_gc()) {
1052 return false;
1053 }
1054 }
1055 return true;
1056 }
1057
1058 void GenCollectedHeap::save_marks() {
1059 for (int i = 0; i < _n_gens; i++) {
1060 _gens[i]->save_marks();
1061 }
1062 }
1063
1064 GenCollectedHeap* GenCollectedHeap::heap() {
1065 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1066 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1067 return _gch;
1068 }
1069
1070
1071 void GenCollectedHeap::prepare_for_compaction() {
1072 guarantee(_n_gens = 2, "Wrong number of generations");
1073 Generation* old_gen = _gens[1];
1074 // Start by compacting into same gen.
1075 CompactPoint cp(old_gen);
1076 old_gen->prepare_for_compaction(&cp);
1077 Generation* young_gen = _gens[0];
1078 young_gen->prepare_for_compaction(&cp);
1079 }
1080
1081 GCStats* GenCollectedHeap::gc_stats(int level) const {
1082 return _gens[level]->gc_stats();
1083 }
1084
1085 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1086 for (int i = _n_gens-1; i >= 0; i--) {
1087 Generation* g = _gens[i];
1088 if (!silent) {
1089 gclog_or_tty->print("%s", g->name());
1090 gclog_or_tty->print(" ");
1091 }
1092 g->verify();
1093 }
1094 if (!silent) {
1095 gclog_or_tty->print("remset ");
1096 }
1097 rem_set()->verify();
1098 }
1099
1100 void GenCollectedHeap::print_on(outputStream* st) const {
1101 for (int i = 0; i < _n_gens; i++) {
1102 _gens[i]->print_on(st);
1103 }
1104 MetaspaceAux::print_on(st);
1105 }
1106
1107 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1108 if (workers() != NULL) {
1109 workers()->threads_do(tc);
1110 }
1111 #if INCLUDE_ALL_GCS
1112 if (UseConcMarkSweepGC) {
1113 ConcurrentMarkSweepThread::threads_do(tc);
1114 }
1115 #endif // INCLUDE_ALL_GCS
1116 }
1117
1118 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1119 #if INCLUDE_ALL_GCS
1120 if (UseConcMarkSweepGC) {
1121 workers()->print_worker_threads_on(st);
1122 ConcurrentMarkSweepThread::print_all_on(st);
1123 }
1124 #endif // INCLUDE_ALL_GCS
1125 }
1126
1127 void GenCollectedHeap::print_on_error(outputStream* st) const {
1128 this->CollectedHeap::print_on_error(st);
1129
1130 #if INCLUDE_ALL_GCS
1131 if (UseConcMarkSweepGC) {
1132 st->cr();
1133 CMSCollector::print_on_error(st);
1134 }
1135 #endif // INCLUDE_ALL_GCS
1136 }
1137
1138 void GenCollectedHeap::print_tracing_info() const {
1139 if (TraceYoungGenTime) {
1140 get_gen(0)->print_summary_info();
1141 }
1142 if (TraceOldGenTime) {
1143 get_gen(1)->print_summary_info();
1144 }
1145 }
1146
1147 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1148 if (PrintGCDetails && Verbose) {
1149 gclog_or_tty->print(" " SIZE_FORMAT
1150 "->" SIZE_FORMAT
1151 "(" SIZE_FORMAT ")",
1152 prev_used, used(), capacity());
1153 } else {
1154 gclog_or_tty->print(" " SIZE_FORMAT "K"
1155 "->" SIZE_FORMAT "K"
1156 "(" SIZE_FORMAT "K)",
1157 prev_used / K, used() / K, capacity() / K);
1158 }
1159 }
1160
1161 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1162 private:
1163 bool _full;
1164 public:
1165 void do_generation(Generation* gen) {
1166 gen->gc_prologue(_full);
1167 }
1168 GenGCPrologueClosure(bool full) : _full(full) {};
1169 };
1170
1171 void GenCollectedHeap::gc_prologue(bool full) {
1172 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1173
1174 always_do_update_barrier = false;
1175 // Fill TLAB's and such
1176 CollectedHeap::accumulate_statistics_all_tlabs();
1177 ensure_parsability(true); // retire TLABs
1178
1179 // Walk generations
1180 GenGCPrologueClosure blk(full);
1181 generation_iterate(&blk, false); // not old-to-young.
1182 };
1183
1184 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1185 private:
1186 bool _full;
1187 public:
1188 void do_generation(Generation* gen) {
1189 gen->gc_epilogue(_full);
1190 }
1191 GenGCEpilogueClosure(bool full) : _full(full) {};
1192 };
1193
1194 void GenCollectedHeap::gc_epilogue(bool full) {
1195 #ifdef COMPILER2
1196 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1197 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1198 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1199 #endif /* COMPILER2 */
1200
1201 resize_all_tlabs();
1202
1203 GenGCEpilogueClosure blk(full);
1204 generation_iterate(&blk, false); // not old-to-young.
1205
1206 if (!CleanChunkPoolAsync) {
1207 Chunk::clean_chunk_pool();
1208 }
1209
1210 MetaspaceCounters::update_performance_counters();
1211 CompressedClassSpaceCounters::update_performance_counters();
1212
1213 always_do_update_barrier = UseConcMarkSweepGC;
1214 };
1215
1216 #ifndef PRODUCT
1217 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1218 private:
1219 public:
1220 void do_generation(Generation* gen) {
1221 gen->record_spaces_top();
1222 }
1223 };
1224
1225 void GenCollectedHeap::record_gen_tops_before_GC() {
1226 if (ZapUnusedHeapArea) {
1227 GenGCSaveTopsBeforeGCClosure blk;
1228 generation_iterate(&blk, false); // not old-to-young.
1229 }
1230 }
1231 #endif // not PRODUCT
1232
1233 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1234 public:
1235 void do_generation(Generation* gen) {
1236 gen->ensure_parsability();
1237 }
1238 };
1239
1240 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1241 CollectedHeap::ensure_parsability(retire_tlabs);
1242 GenEnsureParsabilityClosure ep_cl;
1243 generation_iterate(&ep_cl, false);
1244 }
1245
1246 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1247 oop obj,
1248 size_t obj_size) {
1249 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1250 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1251 HeapWord* result = NULL;
1252
1253 result = old_gen->expand_and_allocate(obj_size, false);
1254
1255 if (result != NULL) {
1256 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1257 }
1258 return oop(result);
1259 }
1260
1261 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1262 jlong _time; // in ms
1263 jlong _now; // in ms
1264
1265 public:
1266 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1267
1268 jlong time() { return _time; }
1269
1270 void do_generation(Generation* gen) {
1271 _time = MIN2(_time, gen->time_of_last_gc(_now));
1272 }
1273 };
1274
1275 jlong GenCollectedHeap::millis_since_last_gc() {
1276 // We need a monotonically non-decreasing time in ms but
1277 // os::javaTimeMillis() does not guarantee monotonicity.
1278 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1279 GenTimeOfLastGCClosure tolgc_cl(now);
1280 // iterate over generations getting the oldest
1281 // time that a generation was collected
1282 generation_iterate(&tolgc_cl, false);
1283
1284 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1285 // provided the underlying platform provides such a time source
1286 // (and it is bug free). So we still have to guard against getting
1287 // back a time later than 'now'.
1288 jlong retVal = now - tolgc_cl.time();
1289 if (retVal < 0) {
1290 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1291 return 0;
1292 }
1293 return retVal;
1294 }