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