1 /*
2 * Copyright (c) 2000, 2015, 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 ReservedSpace heap_rs;
112
113 size_t heap_alignment = collector_policy()->heap_alignment();
114
115 heap_address = allocate(heap_alignment, &heap_rs);
116
117 if (!heap_rs.is_reserved()) {
118 vm_shutdown_during_initialization(
119 "Could not reserve enough space for object heap");
120 return JNI_ENOMEM;
121 }
122
123 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
124
125 _rem_set = collector_policy()->create_rem_set(reserved_region());
126 set_barrier_set(rem_set()->bs());
127
128 _gch = this;
129
130 for (i = 0; i < _n_gens; i++) {
131 ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
132 _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
133 heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
134 }
135 clear_incremental_collection_failed();
136
137 #if INCLUDE_ALL_GCS
138 // If we are running CMS, create the collector responsible
139 // for collecting the CMS generations.
140 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
141 bool success = create_cms_collector();
142 if (!success) return JNI_ENOMEM;
143 }
144 #endif // INCLUDE_ALL_GCS
145
146 return JNI_OK;
147 }
148
149
150 char* GenCollectedHeap::allocate(size_t alignment,
151 ReservedSpace* heap_rs){
152 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
153 "the maximum representable size";
154
155 // Now figure out the total size.
156 size_t total_reserved = 0;
157 const size_t pageSize = UseLargePages ?
158 os::large_page_size() : os::vm_page_size();
159
160 assert(alignment % pageSize == 0, "Must be");
161
162 for (int i = 0; i < _n_gens; i++) {
163 total_reserved += _gen_specs[i]->max_size();
164 if (total_reserved < _gen_specs[i]->max_size()) {
165 vm_exit_during_initialization(overflow_msg);
166 }
167 }
168 assert(total_reserved % alignment == 0,
169 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
170 SIZE_FORMAT, total_reserved, alignment));
171
172 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
173 return heap_rs->base();
174 }
175
176
177 void GenCollectedHeap::post_initialize() {
178 SharedHeap::post_initialize();
179 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
180 guarantee(policy->is_generation_policy(), "Illegal policy type");
181 assert((get_gen(0)->kind() == Generation::DefNew) ||
182 (get_gen(0)->kind() == Generation::ParNew),
183 "Wrong youngest generation type");
184 DefNewGeneration* def_new_gen = (DefNewGeneration*)get_gen(0);
185
186 Generation* old_gen = get_gen(1);
187 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
188 old_gen->kind() == Generation::MarkSweepCompact,
189 "Wrong generation kind");
190
191 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
192 old_gen->capacity(),
193 def_new_gen->from()->capacity());
194 policy->initialize_gc_policy_counters();
195 }
196
197 void GenCollectedHeap::ref_processing_init() {
198 SharedHeap::ref_processing_init();
199 for (int i = 0; i < _n_gens; i++) {
200 _gens[i]->ref_processor_init();
201 }
202 }
203
204 size_t GenCollectedHeap::capacity() const {
205 size_t res = 0;
206 for (int i = 0; i < _n_gens; i++) {
207 res += _gens[i]->capacity();
208 }
209 return res;
210 }
211
212 size_t GenCollectedHeap::used() const {
213 size_t res = 0;
214 for (int i = 0; i < _n_gens; i++) {
215 res += _gens[i]->used();
216 }
217 return res;
218 }
219
220 // Save the "used_region" for generations level and lower.
221 void GenCollectedHeap::save_used_regions(int level) {
222 assert(level < _n_gens, "Illegal level parameter");
223 for (int i = level; i >= 0; i--) {
224 _gens[i]->save_used_region();
225 }
226 }
227
228 size_t GenCollectedHeap::max_capacity() const {
229 size_t res = 0;
230 for (int i = 0; i < _n_gens; i++) {
231 res += _gens[i]->max_capacity();
232 }
233 return res;
234 }
235
236 // Update the _full_collections_completed counter
237 // at the end of a stop-world full GC.
238 unsigned int GenCollectedHeap::update_full_collections_completed() {
239 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
240 assert(_full_collections_completed <= _total_full_collections,
241 "Can't complete more collections than were started");
242 _full_collections_completed = _total_full_collections;
243 ml.notify_all();
244 return _full_collections_completed;
245 }
246
247 // Update the _full_collections_completed counter, as appropriate,
248 // at the end of a concurrent GC cycle. Note the conditional update
249 // below to allow this method to be called by a concurrent collector
250 // without synchronizing in any manner with the VM thread (which
251 // may already have initiated a STW full collection "concurrently").
252 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
253 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
254 assert((_full_collections_completed <= _total_full_collections) &&
255 (count <= _total_full_collections),
256 "Can't complete more collections than were started");
257 if (count > _full_collections_completed) {
258 _full_collections_completed = count;
259 ml.notify_all();
260 }
261 return _full_collections_completed;
262 }
263
264
265 #ifndef PRODUCT
266 // Override of memory state checking method in CollectedHeap:
267 // Some collectors (CMS for example) can't have badHeapWordVal written
268 // in the first two words of an object. (For instance , in the case of
269 // CMS these words hold state used to synchronize between certain
270 // (concurrent) GC steps and direct allocating mutators.)
271 // The skip_header_HeapWords() method below, allows us to skip
272 // over the requisite number of HeapWord's. Note that (for
273 // generational collectors) this means that those many words are
274 // skipped in each object, irrespective of the generation in which
275 // that object lives. The resultant loss of precision seems to be
276 // harmless and the pain of avoiding that imprecision appears somewhat
277 // higher than we are prepared to pay for such rudimentary debugging
278 // support.
279 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
280 size_t size) {
281 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
282 // We are asked to check a size in HeapWords,
283 // but the memory is mangled in juint words.
284 juint* start = (juint*) (addr + skip_header_HeapWords());
285 juint* end = (juint*) (addr + size);
286 for (juint* slot = start; slot < end; slot += 1) {
287 assert(*slot == badHeapWordVal,
288 "Found non badHeapWordValue in pre-allocation check");
289 }
290 }
291 }
292 #endif
293
294 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
295 bool is_tlab,
296 bool first_only) {
297 HeapWord* res;
298 for (int i = 0; i < _n_gens; i++) {
299 if (_gens[i]->should_allocate(size, is_tlab)) {
300 res = _gens[i]->allocate(size, is_tlab);
301 if (res != NULL) return res;
302 else if (first_only) break;
303 }
304 }
305 // Otherwise...
306 return NULL;
307 }
308
309 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
310 bool* gc_overhead_limit_was_exceeded) {
311 return collector_policy()->mem_allocate_work(size,
312 false /* is_tlab */,
313 gc_overhead_limit_was_exceeded);
314 }
315
316 bool GenCollectedHeap::must_clear_all_soft_refs() {
317 return _gc_cause == GCCause::_last_ditch_collection;
318 }
319
320 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
321 return UseConcMarkSweepGC &&
322 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
323 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
324 }
325
326 void GenCollectedHeap::do_collection(bool full,
327 bool clear_all_soft_refs,
328 size_t size,
329 bool is_tlab,
330 int max_level) {
331 bool prepared_for_verification = false;
332 ResourceMark rm;
333 DEBUG_ONLY(Thread* my_thread = Thread::current();)
334
335 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
336 assert(my_thread->is_VM_thread() ||
337 my_thread->is_ConcurrentGC_thread(),
338 "incorrect thread type capability");
339 assert(Heap_lock->is_locked(),
340 "the requesting thread should have the Heap_lock");
341 guarantee(!is_gc_active(), "collection is not reentrant");
342 assert(max_level < n_gens(), "sanity check");
343
344 if (GC_locker::check_active_before_gc()) {
345 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
346 }
347
348 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
349 collector_policy()->should_clear_all_soft_refs();
350
351 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
352
353 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
354
355 print_heap_before_gc();
356
357 {
358 FlagSetting fl(_is_gc_active, true);
359
360 bool complete = full && (max_level == (n_gens()-1));
361 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
362 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
363 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
364 // so we can assume here that the next GC id is what we want.
365 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
366
367 gc_prologue(complete);
368 increment_total_collections(complete);
369
370 size_t gch_prev_used = used();
371
372 int starting_level = 0;
373 if (full) {
374 // Search for the oldest generation which will collect all younger
375 // generations, and start collection loop there.
376 for (int i = max_level; i >= 0; i--) {
377 if (_gens[i]->full_collects_younger_generations()) {
378 starting_level = i;
379 break;
380 }
381 }
382 }
383
384 bool must_restore_marks_for_biased_locking = false;
385
386 int max_level_collected = starting_level;
387 for (int i = starting_level; i <= max_level; i++) {
388 if (_gens[i]->should_collect(full, size, is_tlab)) {
389 if (i == n_gens() - 1) { // a major collection is to happen
390 if (!complete) {
391 // The full_collections increment was missed above.
392 increment_total_full_collections();
393 }
394 pre_full_gc_dump(NULL); // do any pre full gc dumps
395 }
396 // Timer for individual generations. Last argument is false: no CR
397 // FIXME: We should try to start the timing earlier to cover more of the GC pause
398 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
399 // so we can assume here that the next GC id is what we want.
400 GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
401 TraceCollectorStats tcs(_gens[i]->counters());
402 TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
403
404 size_t prev_used = _gens[i]->used();
405 _gens[i]->stat_record()->invocations++;
406 _gens[i]->stat_record()->accumulated_time.start();
407
408 // Must be done anew before each collection because
409 // a previous collection will do mangling and will
410 // change top of some spaces.
411 record_gen_tops_before_GC();
412
413 if (PrintGC && Verbose) {
414 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
415 i,
416 _gens[i]->stat_record()->invocations,
417 size*HeapWordSize);
418 }
419
420 if (VerifyBeforeGC && i >= VerifyGCLevel &&
421 total_collections() >= VerifyGCStartAt) {
422 HandleMark hm; // Discard invalid handles created during verification
423 if (!prepared_for_verification) {
424 prepare_for_verify();
425 prepared_for_verification = true;
426 }
427 Universe::verify(" VerifyBeforeGC:");
428 }
429 COMPILER2_PRESENT(DerivedPointerTable::clear());
430
431 if (!must_restore_marks_for_biased_locking &&
432 _gens[i]->performs_in_place_marking()) {
433 // We perform this mark word preservation work lazily
434 // because it's only at this point that we know whether we
435 // absolutely have to do it; we want to avoid doing it for
436 // scavenge-only collections where it's unnecessary
437 must_restore_marks_for_biased_locking = true;
438 BiasedLocking::preserve_marks();
439 }
440
441 // Do collection work
442 {
443 // Note on ref discovery: For what appear to be historical reasons,
444 // GCH enables and disabled (by enqueing) refs discovery.
445 // In the future this should be moved into the generation's
446 // collect method so that ref discovery and enqueueing concerns
447 // are local to a generation. The collect method could return
448 // an appropriate indication in the case that notification on
449 // the ref lock was needed. This will make the treatment of
450 // weak refs more uniform (and indeed remove such concerns
451 // from GCH). XXX
452
453 HandleMark hm; // Discard invalid handles created during gc
454 save_marks(); // save marks for all gens
455 // We want to discover references, but not process them yet.
456 // This mode is disabled in process_discovered_references if the
457 // generation does some collection work, or in
458 // enqueue_discovered_references if the generation returns
459 // without doing any work.
460 ReferenceProcessor* rp = _gens[i]->ref_processor();
461 // If the discovery of ("weak") refs in this generation is
462 // atomic wrt other collectors in this configuration, we
463 // are guaranteed to have empty discovered ref lists.
464 if (rp->discovery_is_atomic()) {
465 rp->enable_discovery();
466 rp->setup_policy(do_clear_all_soft_refs);
467 } else {
468 // collect() below will enable discovery as appropriate
469 }
470 _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
471 if (!rp->enqueuing_is_done()) {
472 rp->enqueue_discovered_references();
473 } else {
474 rp->set_enqueuing_is_done(false);
475 }
476 rp->verify_no_references_recorded();
477 }
478 max_level_collected = i;
479
480 // Determine if allocation request was met.
481 if (size > 0) {
482 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
483 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
484 size = 0;
485 }
486 }
487 }
488
489 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
490
491 _gens[i]->stat_record()->accumulated_time.stop();
492
493 update_gc_stats(i, full);
494
495 if (VerifyAfterGC && i >= VerifyGCLevel &&
496 total_collections() >= VerifyGCStartAt) {
497 HandleMark hm; // Discard invalid handles created during verification
498 Universe::verify(" VerifyAfterGC:");
499 }
500
501 if (PrintGCDetails) {
502 gclog_or_tty->print(":");
503 _gens[i]->print_heap_change(prev_used);
504 }
505 }
506 }
507
508 // Update "complete" boolean wrt what actually transpired --
509 // for instance, a promotion failure could have led to
510 // a whole heap collection.
511 complete = complete || (max_level_collected == n_gens() - 1);
512
513 if (complete) { // We did a "major" collection
514 // FIXME: See comment at pre_full_gc_dump call
515 post_full_gc_dump(NULL); // do any post full gc dumps
516 }
517
518 if (PrintGCDetails) {
519 print_heap_change(gch_prev_used);
520
521 // Print metaspace info for full GC with PrintGCDetails flag.
522 if (complete) {
523 MetaspaceAux::print_metaspace_change(metadata_prev_used);
524 }
525 }
526
527 for (int j = max_level_collected; j >= 0; j -= 1) {
528 // Adjust generation sizes.
529 _gens[j]->compute_new_size();
530 }
531
532 if (complete) {
533 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
534 ClassLoaderDataGraph::purge();
535 MetaspaceAux::verify_metrics();
536 // Resize the metaspace capacity after full collections
537 MetaspaceGC::compute_new_size();
538 update_full_collections_completed();
539 }
540
541 // Track memory usage and detect low memory after GC finishes
542 MemoryService::track_memory_usage();
543
544 gc_epilogue(complete);
545
546 if (must_restore_marks_for_biased_locking) {
547 BiasedLocking::restore_marks();
548 }
549 }
550
551 print_heap_after_gc();
552
553 #ifdef TRACESPINNING
554 ParallelTaskTerminator::print_termination_counts();
555 #endif
556 }
557
558 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
559 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
560 }
561
562 void GenCollectedHeap::set_par_threads(uint t) {
563 SharedHeap::set_par_threads(t);
564 _gen_process_roots_tasks->set_n_threads(t);
565 }
566
567 void GenCollectedHeap::
568 gen_process_roots(int level,
569 bool younger_gens_as_roots,
570 bool activate_scope,
571 SharedHeap::ScanningOption so,
572 OopsInGenClosure* not_older_gens,
573 OopsInGenClosure* weak_roots,
574 OopsInGenClosure* older_gens,
575 CLDClosure* cld_closure,
576 CLDClosure* weak_cld_closure,
577 CodeBlobClosure* code_closure) {
578
579 // General roots.
580 SharedHeap::process_roots(activate_scope, so,
581 not_older_gens, weak_roots,
582 cld_closure, weak_cld_closure,
583 code_closure);
584
585 if (younger_gens_as_roots) {
586 if (!_gen_process_roots_tasks->is_task_claimed(GCH_PS_younger_gens)) {
587 for (int i = 0; i < level; i++) {
588 not_older_gens->set_generation(_gens[i]);
589 _gens[i]->oop_iterate(not_older_gens);
590 }
591 not_older_gens->reset_generation();
592 }
593 }
594 // When collection is parallel, all threads get to cooperate to do
595 // older-gen scanning.
596 for (int i = level+1; i < _n_gens; i++) {
597 older_gens->set_generation(_gens[i]);
598 rem_set()->younger_refs_iterate(_gens[i], older_gens);
599 older_gens->reset_generation();
600 }
601
602 _gen_process_roots_tasks->all_tasks_completed();
603 }
604
605 void GenCollectedHeap::
606 gen_process_roots(int level,
607 bool younger_gens_as_roots,
608 bool activate_scope,
609 SharedHeap::ScanningOption so,
610 bool only_strong_roots,
611 OopsInGenClosure* not_older_gens,
612 OopsInGenClosure* older_gens,
613 CLDClosure* cld_closure) {
614
615 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
616
617 bool is_moving_collection = false;
618 if (level == 0 || is_adjust_phase) {
619 // young collections are always moving
620 is_moving_collection = true;
621 }
622
623 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
624 CodeBlobClosure* code_closure = &mark_code_closure;
625
626 gen_process_roots(level,
627 younger_gens_as_roots,
628 activate_scope, so,
629 not_older_gens, only_strong_roots ? NULL : not_older_gens,
630 older_gens,
631 cld_closure, only_strong_roots ? NULL : cld_closure,
632 code_closure);
633
634 }
635
636 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
637 SharedHeap::process_weak_roots(root_closure);
638 // "Local" "weak" refs
639 for (int i = 0; i < _n_gens; i++) {
640 _gens[i]->ref_processor()->weak_oops_do(root_closure);
641 }
642 }
643
644 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
645 void GenCollectedHeap:: \
646 oop_since_save_marks_iterate(int level, \
647 OopClosureType* cur, \
648 OopClosureType* older) { \
649 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
650 for (int i = level+1; i < n_gens(); i++) { \
651 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
652 } \
653 }
654
655 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
656
657 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
658
659 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
660 for (int i = level; i < _n_gens; i++) {
661 if (!_gens[i]->no_allocs_since_save_marks()) return false;
662 }
663 return true;
664 }
665
666 bool GenCollectedHeap::supports_inline_contig_alloc() const {
667 return _gens[0]->supports_inline_contig_alloc();
668 }
669
670 HeapWord** GenCollectedHeap::top_addr() const {
671 return _gens[0]->top_addr();
672 }
673
674 HeapWord** GenCollectedHeap::end_addr() const {
675 return _gens[0]->end_addr();
676 }
677
678 // public collection interfaces
679
680 void GenCollectedHeap::collect(GCCause::Cause cause) {
681 if (should_do_concurrent_full_gc(cause)) {
682 #if INCLUDE_ALL_GCS
683 // mostly concurrent full collection
684 collect_mostly_concurrent(cause);
685 #else // INCLUDE_ALL_GCS
686 ShouldNotReachHere();
687 #endif // INCLUDE_ALL_GCS
688 } else if (cause == GCCause::_wb_young_gc) {
689 // minor collection for WhiteBox API
690 collect(cause, 0);
691 } else {
692 #ifdef ASSERT
693 if (cause == GCCause::_scavenge_alot) {
694 // minor collection only
695 collect(cause, 0);
696 } else {
697 // Stop-the-world full collection
698 collect(cause, n_gens() - 1);
699 }
700 #else
701 // Stop-the-world full collection
702 collect(cause, n_gens() - 1);
703 #endif
704 }
705 }
706
707 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
708 // The caller doesn't have the Heap_lock
709 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
710 MutexLocker ml(Heap_lock);
711 collect_locked(cause, max_level);
712 }
713
714 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
715 // The caller has the Heap_lock
716 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
717 collect_locked(cause, n_gens() - 1);
718 }
719
720 // this is the private collection interface
721 // The Heap_lock is expected to be held on entry.
722
723 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
724 // Read the GC count while holding the Heap_lock
725 unsigned int gc_count_before = total_collections();
726 unsigned int full_gc_count_before = total_full_collections();
727 {
728 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
729 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
730 cause, max_level);
731 VMThread::execute(&op);
732 }
733 }
734
735 #if INCLUDE_ALL_GCS
736 bool GenCollectedHeap::create_cms_collector() {
737
738 assert(_gens[1]->kind() == Generation::ConcurrentMarkSweep,
739 "Unexpected generation kinds");
740 // Skip two header words in the block content verification
741 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
742 CMSCollector* collector = new CMSCollector(
743 (ConcurrentMarkSweepGeneration*)_gens[1],
744 _rem_set->as_CardTableRS(),
745 (ConcurrentMarkSweepPolicy*) collector_policy());
746
747 if (collector == NULL || !collector->completed_initialization()) {
748 if (collector) {
749 delete collector; // Be nice in embedded situation
750 }
751 vm_shutdown_during_initialization("Could not create CMS collector");
752 return false;
753 }
754 return true; // success
755 }
756
757 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
758 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
759
760 MutexLocker ml(Heap_lock);
761 // Read the GC counts while holding the Heap_lock
762 unsigned int full_gc_count_before = total_full_collections();
763 unsigned int gc_count_before = total_collections();
764 {
765 MutexUnlocker mu(Heap_lock);
766 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
767 VMThread::execute(&op);
768 }
769 }
770 #endif // INCLUDE_ALL_GCS
771
772 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
773 do_full_collection(clear_all_soft_refs, _n_gens - 1);
774 }
775
776 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
777 int max_level) {
778 int local_max_level;
779 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
780 gc_cause() == GCCause::_gc_locker) {
781 local_max_level = 0;
782 } else {
783 local_max_level = max_level;
784 }
785
786 do_collection(true /* full */,
787 clear_all_soft_refs /* clear_all_soft_refs */,
788 0 /* size */,
789 false /* is_tlab */,
790 local_max_level /* max_level */);
791 // Hack XXX FIX ME !!!
792 // A scavenge may not have been attempted, or may have
793 // been attempted and failed, because the old gen was too full
794 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
795 incremental_collection_will_fail(false /* don't consult_young */)) {
796 if (PrintGCDetails) {
797 gclog_or_tty->print_cr("GC locker: Trying a full collection "
798 "because scavenge failed");
799 }
800 // This time allow the old gen to be collected as well
801 do_collection(true /* full */,
802 clear_all_soft_refs /* clear_all_soft_refs */,
803 0 /* size */,
804 false /* is_tlab */,
805 n_gens() - 1 /* max_level */);
806 }
807 }
808
809 bool GenCollectedHeap::is_in_young(oop p) {
810 bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
811 assert(result == _gens[0]->is_in_reserved(p),
812 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
813 return result;
814 }
815
816 // Returns "TRUE" iff "p" points into the committed areas of the heap.
817 bool GenCollectedHeap::is_in(const void* p) const {
818 #ifndef ASSERT
819 guarantee(VerifyBeforeGC ||
820 VerifyDuringGC ||
821 VerifyBeforeExit ||
822 VerifyDuringStartup ||
823 PrintAssembly ||
824 tty->count() != 0 || // already printing
825 VerifyAfterGC ||
826 VMError::fatal_error_in_progress(), "too expensive");
827
828 #endif
829 // This might be sped up with a cache of the last generation that
830 // answered yes.
831 for (int i = 0; i < _n_gens; i++) {
832 if (_gens[i]->is_in(p)) return true;
833 }
834 // Otherwise...
835 return false;
836 }
837
838 #ifdef ASSERT
839 // Don't implement this by using is_in_young(). This method is used
840 // in some cases to check that is_in_young() is correct.
841 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
842 assert(is_in_reserved(p) || p == NULL,
843 "Does not work if address is non-null and outside of the heap");
844 return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
845 }
846 #endif
847
848 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
849 for (int i = 0; i < _n_gens; i++) {
850 _gens[i]->oop_iterate(cl);
851 }
852 }
853
854 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
855 for (int i = 0; i < _n_gens; i++) {
856 _gens[i]->object_iterate(cl);
857 }
858 }
859
860 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
861 for (int i = 0; i < _n_gens; i++) {
862 _gens[i]->safe_object_iterate(cl);
863 }
864 }
865
866 Space* GenCollectedHeap::space_containing(const void* addr) const {
867 for (int i = 0; i < _n_gens; i++) {
868 Space* res = _gens[i]->space_containing(addr);
869 if (res != NULL) return res;
870 }
871 // Otherwise...
872 assert(false, "Could not find containing space");
873 return NULL;
874 }
875
876
877 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
878 assert(is_in_reserved(addr), "block_start of address outside of heap");
879 for (int i = 0; i < _n_gens; i++) {
880 if (_gens[i]->is_in_reserved(addr)) {
881 assert(_gens[i]->is_in(addr),
882 "addr should be in allocated part of generation");
883 return _gens[i]->block_start(addr);
884 }
885 }
886 assert(false, "Some generation should contain the address");
887 return NULL;
888 }
889
890 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
891 assert(is_in_reserved(addr), "block_size of address outside of heap");
892 for (int i = 0; i < _n_gens; i++) {
893 if (_gens[i]->is_in_reserved(addr)) {
894 assert(_gens[i]->is_in(addr),
895 "addr should be in allocated part of generation");
896 return _gens[i]->block_size(addr);
897 }
898 }
899 assert(false, "Some generation should contain the address");
900 return 0;
901 }
902
903 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
904 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
905 assert(block_start(addr) == addr, "addr must be a block start");
906 for (int i = 0; i < _n_gens; i++) {
907 if (_gens[i]->is_in_reserved(addr)) {
908 return _gens[i]->block_is_obj(addr);
909 }
910 }
911 assert(false, "Some generation should contain the address");
912 return false;
913 }
914
915 bool GenCollectedHeap::supports_tlab_allocation() const {
916 for (int i = 0; i < _n_gens; i += 1) {
917 if (_gens[i]->supports_tlab_allocation()) {
918 return true;
919 }
920 }
921 return false;
922 }
923
924 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
925 size_t result = 0;
926 for (int i = 0; i < _n_gens; i += 1) {
927 if (_gens[i]->supports_tlab_allocation()) {
928 result += _gens[i]->tlab_capacity();
929 }
930 }
931 return result;
932 }
933
934 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
935 size_t result = 0;
936 for (int i = 0; i < _n_gens; i += 1) {
937 if (_gens[i]->supports_tlab_allocation()) {
938 result += _gens[i]->tlab_used();
939 }
940 }
941 return result;
942 }
943
944 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
945 size_t result = 0;
946 for (int i = 0; i < _n_gens; i += 1) {
947 if (_gens[i]->supports_tlab_allocation()) {
948 result += _gens[i]->unsafe_max_tlab_alloc();
949 }
950 }
951 return result;
952 }
953
954 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
955 bool gc_overhead_limit_was_exceeded;
956 return collector_policy()->mem_allocate_work(size /* size */,
957 true /* is_tlab */,
958 &gc_overhead_limit_was_exceeded);
959 }
960
961 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
962 // from the list headed by "*prev_ptr".
963 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
964 bool first = true;
965 size_t min_size = 0; // "first" makes this conceptually infinite.
966 ScratchBlock **smallest_ptr, *smallest;
967 ScratchBlock *cur = *prev_ptr;
968 while (cur) {
969 assert(*prev_ptr == cur, "just checking");
970 if (first || cur->num_words < min_size) {
971 smallest_ptr = prev_ptr;
972 smallest = cur;
973 min_size = smallest->num_words;
974 first = false;
975 }
976 prev_ptr = &cur->next;
977 cur = cur->next;
978 }
979 smallest = *smallest_ptr;
980 *smallest_ptr = smallest->next;
981 return smallest;
982 }
983
984 // Sort the scratch block list headed by res into decreasing size order,
985 // and set "res" to the result.
986 static void sort_scratch_list(ScratchBlock*& list) {
987 ScratchBlock* sorted = NULL;
988 ScratchBlock* unsorted = list;
989 while (unsorted) {
990 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
991 smallest->next = sorted;
992 sorted = smallest;
993 }
994 list = sorted;
995 }
996
997 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
998 size_t max_alloc_words) {
999 ScratchBlock* res = NULL;
1000 for (int i = 0; i < _n_gens; i++) {
1001 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1002 }
1003 sort_scratch_list(res);
1004 return res;
1005 }
1006
1007 void GenCollectedHeap::release_scratch() {
1008 for (int i = 0; i < _n_gens; i++) {
1009 _gens[i]->reset_scratch();
1010 }
1011 }
1012
1013 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1014 void do_generation(Generation* gen) {
1015 gen->prepare_for_verify();
1016 }
1017 };
1018
1019 void GenCollectedHeap::prepare_for_verify() {
1020 ensure_parsability(false); // no need to retire TLABs
1021 GenPrepareForVerifyClosure blk;
1022 generation_iterate(&blk, false);
1023 }
1024
1025
1026 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1027 bool old_to_young) {
1028 if (old_to_young) {
1029 for (int i = _n_gens-1; i >= 0; i--) {
1030 cl->do_generation(_gens[i]);
1031 }
1032 } else {
1033 for (int i = 0; i < _n_gens; i++) {
1034 cl->do_generation(_gens[i]);
1035 }
1036 }
1037 }
1038
1039 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1040 for (int i = 0; i < _n_gens; i++) {
1041 _gens[i]->space_iterate(cl, true);
1042 }
1043 }
1044
1045 bool GenCollectedHeap::is_maximal_no_gc() const {
1046 for (int i = 0; i < _n_gens; i++) {
1047 if (!_gens[i]->is_maximal_no_gc()) {
1048 return false;
1049 }
1050 }
1051 return true;
1052 }
1053
1054 void GenCollectedHeap::save_marks() {
1055 for (int i = 0; i < _n_gens; i++) {
1056 _gens[i]->save_marks();
1057 }
1058 }
1059
1060 GenCollectedHeap* GenCollectedHeap::heap() {
1061 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1062 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1063 return _gch;
1064 }
1065
1066
1067 void GenCollectedHeap::prepare_for_compaction() {
1068 guarantee(_n_gens = 2, "Wrong number of generations");
1069 Generation* old_gen = _gens[1];
1070 // Start by compacting into same gen.
1071 CompactPoint cp(old_gen);
1072 old_gen->prepare_for_compaction(&cp);
1073 Generation* young_gen = _gens[0];
1074 young_gen->prepare_for_compaction(&cp);
1075 }
1076
1077 GCStats* GenCollectedHeap::gc_stats(int level) const {
1078 return _gens[level]->gc_stats();
1079 }
1080
1081 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1082 for (int i = _n_gens-1; i >= 0; i--) {
1083 Generation* g = _gens[i];
1084 if (!silent) {
1085 gclog_or_tty->print("%s", g->name());
1086 gclog_or_tty->print(" ");
1087 }
1088 g->verify();
1089 }
1090 if (!silent) {
1091 gclog_or_tty->print("remset ");
1092 }
1093 rem_set()->verify();
1094 }
1095
1096 void GenCollectedHeap::print_on(outputStream* st) const {
1097 for (int i = 0; i < _n_gens; i++) {
1098 _gens[i]->print_on(st);
1099 }
1100 MetaspaceAux::print_on(st);
1101 }
1102
1103 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1104 if (workers() != NULL) {
1105 workers()->threads_do(tc);
1106 }
1107 #if INCLUDE_ALL_GCS
1108 if (UseConcMarkSweepGC) {
1109 ConcurrentMarkSweepThread::threads_do(tc);
1110 }
1111 #endif // INCLUDE_ALL_GCS
1112 }
1113
1114 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1115 #if INCLUDE_ALL_GCS
1116 if (UseConcMarkSweepGC) {
1117 workers()->print_worker_threads_on(st);
1118 ConcurrentMarkSweepThread::print_all_on(st);
1119 }
1120 #endif // INCLUDE_ALL_GCS
1121 }
1122
1123 void GenCollectedHeap::print_on_error(outputStream* st) const {
1124 this->CollectedHeap::print_on_error(st);
1125
1126 #if INCLUDE_ALL_GCS
1127 if (UseConcMarkSweepGC) {
1128 st->cr();
1129 CMSCollector::print_on_error(st);
1130 }
1131 #endif // INCLUDE_ALL_GCS
1132 }
1133
1134 void GenCollectedHeap::print_tracing_info() const {
1135 if (TraceYoungGenTime) {
1136 get_gen(0)->print_summary_info();
1137 }
1138 if (TraceOldGenTime) {
1139 get_gen(1)->print_summary_info();
1140 }
1141 }
1142
1143 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1144 if (PrintGCDetails && Verbose) {
1145 gclog_or_tty->print(" " SIZE_FORMAT
1146 "->" SIZE_FORMAT
1147 "(" SIZE_FORMAT ")",
1148 prev_used, used(), capacity());
1149 } else {
1150 gclog_or_tty->print(" " SIZE_FORMAT "K"
1151 "->" SIZE_FORMAT "K"
1152 "(" SIZE_FORMAT "K)",
1153 prev_used / K, used() / K, capacity() / K);
1154 }
1155 }
1156
1157 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1158 private:
1159 bool _full;
1160 public:
1161 void do_generation(Generation* gen) {
1162 gen->gc_prologue(_full);
1163 }
1164 GenGCPrologueClosure(bool full) : _full(full) {};
1165 };
1166
1167 void GenCollectedHeap::gc_prologue(bool full) {
1168 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1169
1170 always_do_update_barrier = false;
1171 // Fill TLAB's and such
1172 CollectedHeap::accumulate_statistics_all_tlabs();
1173 ensure_parsability(true); // retire TLABs
1174
1175 // Walk generations
1176 GenGCPrologueClosure blk(full);
1177 generation_iterate(&blk, false); // not old-to-young.
1178 };
1179
1180 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1181 private:
1182 bool _full;
1183 public:
1184 void do_generation(Generation* gen) {
1185 gen->gc_epilogue(_full);
1186 }
1187 GenGCEpilogueClosure(bool full) : _full(full) {};
1188 };
1189
1190 void GenCollectedHeap::gc_epilogue(bool full) {
1191 #ifdef COMPILER2
1192 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1193 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1194 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1195 #endif /* COMPILER2 */
1196
1197 resize_all_tlabs();
1198
1199 GenGCEpilogueClosure blk(full);
1200 generation_iterate(&blk, false); // not old-to-young.
1201
1202 if (!CleanChunkPoolAsync) {
1203 Chunk::clean_chunk_pool();
1204 }
1205
1206 MetaspaceCounters::update_performance_counters();
1207 CompressedClassSpaceCounters::update_performance_counters();
1208
1209 always_do_update_barrier = UseConcMarkSweepGC;
1210 };
1211
1212 #ifndef PRODUCT
1213 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1214 private:
1215 public:
1216 void do_generation(Generation* gen) {
1217 gen->record_spaces_top();
1218 }
1219 };
1220
1221 void GenCollectedHeap::record_gen_tops_before_GC() {
1222 if (ZapUnusedHeapArea) {
1223 GenGCSaveTopsBeforeGCClosure blk;
1224 generation_iterate(&blk, false); // not old-to-young.
1225 }
1226 }
1227 #endif // not PRODUCT
1228
1229 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1230 public:
1231 void do_generation(Generation* gen) {
1232 gen->ensure_parsability();
1233 }
1234 };
1235
1236 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1237 CollectedHeap::ensure_parsability(retire_tlabs);
1238 GenEnsureParsabilityClosure ep_cl;
1239 generation_iterate(&ep_cl, false);
1240 }
1241
1242 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1243 oop obj,
1244 size_t obj_size) {
1245 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1246 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1247 HeapWord* result = NULL;
1248
1249 result = old_gen->expand_and_allocate(obj_size, false);
1250
1251 if (result != NULL) {
1252 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1253 }
1254 return oop(result);
1255 }
1256
1257 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1258 jlong _time; // in ms
1259 jlong _now; // in ms
1260
1261 public:
1262 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1263
1264 jlong time() { return _time; }
1265
1266 void do_generation(Generation* gen) {
1267 _time = MIN2(_time, gen->time_of_last_gc(_now));
1268 }
1269 };
1270
1271 jlong GenCollectedHeap::millis_since_last_gc() {
1272 // We need a monotonically non-decreasing time in ms but
1273 // os::javaTimeMillis() does not guarantee monotonicity.
1274 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1275 GenTimeOfLastGCClosure tolgc_cl(now);
1276 // iterate over generations getting the oldest
1277 // time that a generation was collected
1278 generation_iterate(&tolgc_cl, false);
1279
1280 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1281 // provided the underlying platform provides such a time source
1282 // (and it is bug free). So we still have to guard against getting
1283 // back a time later than 'now'.
1284 jlong retVal = now - tolgc_cl.time();
1285 if (retVal < 0) {
1286 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1287 return 0;
1288 }
1289 return retVal;
1290 }