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 int n_covered_regions = 0;
113 ReservedSpace heap_rs;
114
115 size_t heap_alignment = collector_policy()->heap_alignment();
116
117 heap_address = allocate(heap_alignment, &total_reserved,
118 &n_covered_regions, &heap_rs);
119
120 if (!heap_rs.is_reserved()) {
121 vm_shutdown_during_initialization(
122 "Could not reserve enough space for object heap");
123 return JNI_ENOMEM;
124 }
125
126 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
127
128 _rem_set = collector_policy()->create_rem_set(reserved_region(), n_covered_regions);
129 set_barrier_set(rem_set()->bs());
130
131 _gch = this;
132
133 ReservedSpace young_rs = heap_rs.first_part(_gen_specs[0]->max_size(), false, false);
134 _young_gen = _gen_specs[0]->init(young_rs, 0, rem_set());
135 heap_rs = heap_rs.last_part(_gen_specs[0]->max_size());
136
137 ReservedSpace old_rs = heap_rs.first_part(_gen_specs[1]->max_size(), false, false);
138 _old_gen = _gen_specs[1]->init(old_rs, 1, rem_set());
139 heap_rs = heap_rs.last_part(_gen_specs[1]->max_size());
140 clear_incremental_collection_failed();
141
142 #if INCLUDE_ALL_GCS
143 // If we are running CMS, create the collector responsible
144 // for collecting the CMS generations.
145 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
146 bool success = create_cms_collector();
147 if (!success) return JNI_ENOMEM;
148 }
149 #endif // INCLUDE_ALL_GCS
150
151 return JNI_OK;
152 }
153
154 char* GenCollectedHeap::allocate(size_t alignment,
155 size_t* _total_reserved,
156 int* _n_covered_regions,
157 ReservedSpace* heap_rs){
158 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
159 "the maximum representable size";
160
161 // Now figure out the total size.
162 size_t total_reserved = 0;
163 int n_covered_regions = 0;
164 const size_t pageSize = UseLargePages ?
165 os::large_page_size() : os::vm_page_size();
166
167 assert(alignment % pageSize == 0, "Must be");
168
169 for (int i = 0; i < _n_gens; i++) {
170 total_reserved += _gen_specs[i]->max_size();
171 if (total_reserved < _gen_specs[i]->max_size()) {
172 vm_exit_during_initialization(overflow_msg);
173 }
174 n_covered_regions += _gen_specs[i]->n_covered_regions();
175 }
176 assert(total_reserved % alignment == 0,
177 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
178 SIZE_FORMAT, total_reserved, alignment));
179
180 // Needed until the cardtable is fixed to have the right number
181 // of covered regions.
182 n_covered_regions += 2;
183
184 *_total_reserved = total_reserved;
185 *_n_covered_regions = n_covered_regions;
186
187 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
188 return heap_rs->base();
189 }
190
191 void GenCollectedHeap::post_initialize() {
192 SharedHeap::post_initialize();
193 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
194 guarantee(policy->is_generation_policy(), "Illegal policy type");
195 DefNewGeneration* def_new_gen = (DefNewGeneration*) _young_gen;
196 assert(def_new_gen->kind() == Generation::DefNew ||
197 def_new_gen->kind() == Generation::ParNew,
198 "Wrong generation kind");
199
200 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
201 _old_gen->kind() == Generation::MarkSweepCompact,
202 "Wrong generation kind");
203
204 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
205 _old_gen->capacity(),
206 def_new_gen->from()->capacity());
207 policy->initialize_gc_policy_counters();
208 }
209
210 void GenCollectedHeap::ref_processing_init() {
211 SharedHeap::ref_processing_init();
212 _young_gen->ref_processor_init();
213 _old_gen->ref_processor_init();
214 }
215
216 size_t GenCollectedHeap::capacity() const {
217 return _young_gen->capacity() + _old_gen->capacity();
218 }
219
220 size_t GenCollectedHeap::used() const {
221 return _young_gen->used() + _old_gen->used();
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 if (level == 1) {
228 _old_gen->save_used_region();
229 }
230 _young_gen->save_used_region();
231 }
232
233 size_t GenCollectedHeap::max_capacity() const {
234 return _young_gen->max_capacity() + _old_gen->max_capacity();
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 = NULL;
299
300 if (_young_gen->should_allocate(size, is_tlab)) {
301 res = _young_gen->allocate(size, is_tlab);
302 if (res != NULL || first_only) {
303 return res;
304 }
305 }
306
307 if (_old_gen->should_allocate(size, is_tlab)) {
308 res = _old_gen->allocate(size, is_tlab);
309 }
310
311 return res;
312 }
313
314 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
315 bool* gc_overhead_limit_was_exceeded) {
316 return collector_policy()->mem_allocate_work(size,
317 false /* is_tlab */,
318 gc_overhead_limit_was_exceeded);
319 }
320
321 bool GenCollectedHeap::must_clear_all_soft_refs() {
322 return _gc_cause == GCCause::_last_ditch_collection;
323 }
324
325 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
326 return UseConcMarkSweepGC &&
327 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
328 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
329 }
330
331 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
332 bool is_tlab, bool run_verification, bool clear_soft_refs) {
333 // Timer for individual generations. Last argument is false: no CR
334 // FIXME: We should try to start the timing earlier to cover more of the GC pause
335 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
336 // so we can assume here that the next GC id is what we want.
337 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
338 TraceCollectorStats tcs(gen->counters());
339 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
340
341 size_t prev_used = gen->used();
342 gen->stat_record()->invocations++;
343 gen->stat_record()->accumulated_time.start();
344
345 // Must be done anew before each collection because
346 // a previous collection will do mangling and will
347 // change top of some spaces.
348 record_gen_tops_before_GC();
349
350 if (PrintGC && Verbose) {
351 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
352 gen->level(),
353 gen->stat_record()->invocations,
354 size * HeapWordSize);
355 }
356
357 if (run_verification && VerifyBeforeGC) {
358 HandleMark hm; // Discard invalid handles created during verification
359 Universe::verify(" VerifyBeforeGC:");
360 }
361 COMPILER2_PRESENT(DerivedPointerTable::clear());
362
363 // Do collection work
364 {
365 // Note on ref discovery: For what appear to be historical reasons,
366 // GCH enables and disabled (by enqueing) refs discovery.
367 // In the future this should be moved into the generation's
368 // collect method so that ref discovery and enqueueing concerns
369 // are local to a generation. The collect method could return
370 // an appropriate indication in the case that notification on
371 // the ref lock was needed. This will make the treatment of
372 // weak refs more uniform (and indeed remove such concerns
373 // from GCH). XXX
374
375 HandleMark hm; // Discard invalid handles created during gc
376 save_marks(); // save marks for all gens
377 // We want to discover references, but not process them yet.
378 // This mode is disabled in process_discovered_references if the
379 // generation does some collection work, or in
380 // enqueue_discovered_references if the generation returns
381 // without doing any work.
382 ReferenceProcessor* rp = gen->ref_processor();
383 // If the discovery of ("weak") refs in this generation is
384 // atomic wrt other collectors in this configuration, we
385 // are guaranteed to have empty discovered ref lists.
386 if (rp->discovery_is_atomic()) {
387 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
388 rp->setup_policy(clear_soft_refs);
389 } else {
390 // collect() below will enable discovery as appropriate
391 }
392 gen->collect(full, clear_soft_refs, size, is_tlab);
393 if (!rp->enqueuing_is_done()) {
394 rp->enqueue_discovered_references();
395 } else {
396 rp->set_enqueuing_is_done(false);
397 }
398 rp->verify_no_references_recorded();
399 }
400
401 // Determine if allocation request was met.
402 if (size > 0) {
403 if (!is_tlab || gen->supports_tlab_allocation()) {
404 if (size * HeapWordSize <= gen->unsafe_max_alloc_nogc()) {
405 size = 0;
406 }
407 }
408 }
409
410 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
411
412 gen->stat_record()->accumulated_time.stop();
413
414 update_gc_stats(gen->level(), full);
415
416 if (run_verification && VerifyAfterGC) {
417 HandleMark hm; // Discard invalid handles created during verification
418 Universe::verify(" VerifyAfterGC:");
419 }
420
421 if (PrintGCDetails) {
422 gclog_or_tty->print(":");
423 gen->print_heap_change(prev_used);
424 }
425 }
426
427 void GenCollectedHeap::do_collection(bool full,
428 bool clear_all_soft_refs,
429 size_t size,
430 bool is_tlab,
431 int max_level) {
432 ResourceMark rm;
433 DEBUG_ONLY(Thread* my_thread = Thread::current();)
434
435 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
436 assert(my_thread->is_VM_thread() ||
437 my_thread->is_ConcurrentGC_thread(),
438 "incorrect thread type capability");
439 assert(Heap_lock->is_locked(),
440 "the requesting thread should have the Heap_lock");
441 guarantee(!is_gc_active(), "collection is not reentrant");
442 assert(max_level < n_gens(), "sanity check");
443
444 if (GC_locker::check_active_before_gc()) {
445 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
446 }
447
448 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
449 collector_policy()->should_clear_all_soft_refs();
450
451 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
452
453 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
454
455 print_heap_before_gc();
456
457 {
458 FlagSetting fl(_is_gc_active, true);
459
460 bool complete = full && (max_level == (n_gens()-1));
461 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
462 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
463 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
464 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
465 // so we can assume here that the next GC id is what we want.
466 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
467
468 gc_prologue(complete);
469 increment_total_collections(complete);
470
471 size_t gch_prev_used = used();
472 bool must_restore_marks_for_biased_locking = false;
473 bool run_verification = total_collections() >= VerifyGCStartAt;
474
475 if (_young_gen->performs_in_place_marking() ||
476 _old_gen->performs_in_place_marking()) {
477 // We want to avoid doing this for
478 // scavenge-only collections where it's unnecessary.
479 must_restore_marks_for_biased_locking = true;
480 BiasedLocking::preserve_marks();
481 }
482
483 bool prepared_for_verification = false;
484 int max_level_collected = 0;
485 if (!(full && _old_gen->full_collects_younger_generations()) &&
486 _young_gen->should_collect(full, size, is_tlab)) {
487 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
488 prepare_for_verify();
489 prepared_for_verification = true;
490 }
491 collect_generation(_young_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 0, do_clear_all_soft_refs);
492 }
493 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
494 if (!complete) {
495 // The full_collections increment was missed above.
496 increment_total_full_collections();
497 }
498 pre_full_gc_dump(NULL); // do any pre full gc dumps
499 if (run_verification && VerifyGCLevel <= 1 && VerifyBeforeGC) {
500 if (!prepared_for_verification) {
501 prepare_for_verify();
502 }
503 }
504 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs);
505 max_level_collected = 1;
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 // Adjust generation sizes.
528 if (max_level_collected == 1) {
529 _old_gen->compute_new_size();
530 }
531 _young_gen->compute_new_size();
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 if (level == 1) {
589 not_older_gens->set_generation(_young_gen);
590 _young_gen->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 if (level == 0) {
598 older_gens->set_generation(_old_gen);
599 rem_set()->younger_refs_iterate(_old_gen, 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 _young_gen->ref_processor()->weak_oops_do(root_closure);
641 _old_gen->ref_processor()->weak_oops_do(root_closure);
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 if (level == 0) { \
650 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
651 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
652 } else { \
653 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
654 } \
655 }
656
657 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
658
659 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
660
661 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
662 if (level == 0) {
663 if (!_young_gen->no_allocs_since_save_marks()) return false;
664 }
665 if (!_old_gen->no_allocs_since_save_marks()) return false;
666 return true;
667 }
668
669 bool GenCollectedHeap::supports_inline_contig_alloc() const {
670 return _young_gen->supports_inline_contig_alloc();
671 }
672
673 HeapWord** GenCollectedHeap::top_addr() const {
674 return _young_gen->top_addr();
675 }
676
677 HeapWord** GenCollectedHeap::end_addr() const {
678 return _young_gen->end_addr();
679 }
680
681 // public collection interfaces
682
683 void GenCollectedHeap::collect(GCCause::Cause cause) {
684 if (should_do_concurrent_full_gc(cause)) {
685 #if INCLUDE_ALL_GCS
686 // mostly concurrent full collection
687 collect_mostly_concurrent(cause);
688 #else // INCLUDE_ALL_GCS
689 ShouldNotReachHere();
690 #endif // INCLUDE_ALL_GCS
691 } else if (cause == GCCause::_wb_young_gc) {
692 // minor collection for WhiteBox API
693 collect(cause, 0);
694 } else {
695 #ifdef ASSERT
696 if (cause == GCCause::_scavenge_alot) {
697 // minor collection only
698 collect(cause, 0);
699 } else {
700 // Stop-the-world full collection
701 collect(cause, n_gens() - 1);
702 }
703 #else
704 // Stop-the-world full collection
705 collect(cause, n_gens() - 1);
706 #endif
707 }
708 }
709
710 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
711 // The caller doesn't have the Heap_lock
712 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
713 MutexLocker ml(Heap_lock);
714 collect_locked(cause, max_level);
715 }
716
717 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
718 // The caller has the Heap_lock
719 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
720 collect_locked(cause, n_gens() - 1);
721 }
722
723 // this is the private collection interface
724 // The Heap_lock is expected to be held on entry.
725
726 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
727 // Read the GC count while holding the Heap_lock
728 unsigned int gc_count_before = total_collections();
729 unsigned int full_gc_count_before = total_full_collections();
730 {
731 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
732 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
733 cause, max_level);
734 VMThread::execute(&op);
735 }
736 }
737
738 #if INCLUDE_ALL_GCS
739 bool GenCollectedHeap::create_cms_collector() {
740
741 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
742 "Unexpected generation kinds");
743 // Skip two header words in the block content verification
744 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
745 CMSCollector* collector = new CMSCollector(
746 (ConcurrentMarkSweepGeneration*)_old_gen,
747 _rem_set->as_CardTableRS(),
748 (ConcurrentMarkSweepPolicy*) collector_policy());
749
750 if (collector == NULL || !collector->completed_initialization()) {
751 if (collector) {
752 delete collector; // Be nice in embedded situation
753 }
754 vm_shutdown_during_initialization("Could not create CMS collector");
755 return false;
756 }
757 return true; // success
758 }
759
760 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
761 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
762
763 MutexLocker ml(Heap_lock);
764 // Read the GC counts while holding the Heap_lock
765 unsigned int full_gc_count_before = total_full_collections();
766 unsigned int gc_count_before = total_collections();
767 {
768 MutexUnlocker mu(Heap_lock);
769 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
770 VMThread::execute(&op);
771 }
772 }
773 #endif // INCLUDE_ALL_GCS
774
775 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
776 do_full_collection(clear_all_soft_refs, _n_gens - 1);
777 }
778
779 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
780 int max_level) {
781 int local_max_level;
782 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
783 gc_cause() == GCCause::_gc_locker) {
784 local_max_level = 0;
785 } else {
786 local_max_level = max_level;
787 }
788
789 do_collection(true /* full */,
790 clear_all_soft_refs /* clear_all_soft_refs */,
791 0 /* size */,
792 false /* is_tlab */,
793 local_max_level /* max_level */);
794 // Hack XXX FIX ME !!!
795 // A scavenge may not have been attempted, or may have
796 // been attempted and failed, because the old gen was too full
797 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
798 incremental_collection_will_fail(false /* don't consult_young */)) {
799 if (PrintGCDetails) {
800 gclog_or_tty->print_cr("GC locker: Trying a full collection "
801 "because scavenge failed");
802 }
803 // This time allow the old gen to be collected as well
804 do_collection(true /* full */,
805 clear_all_soft_refs /* clear_all_soft_refs */,
806 0 /* size */,
807 false /* is_tlab */,
808 n_gens() - 1 /* max_level */);
809 }
810 }
811
812 bool GenCollectedHeap::is_in_young(oop p) {
813 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
814 assert(result == _young_gen->is_in_reserved(p),
815 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
816 return result;
817 }
818
819 // Returns "TRUE" iff "p" points into the committed areas of the heap.
820 bool GenCollectedHeap::is_in(const void* p) const {
821 #ifndef ASSERT
822 guarantee(VerifyBeforeGC ||
823 VerifyDuringGC ||
824 VerifyBeforeExit ||
825 VerifyDuringStartup ||
826 PrintAssembly ||
827 tty->count() != 0 || // already printing
828 VerifyAfterGC ||
829 VMError::fatal_error_in_progress(), "too expensive");
830
831 #endif
832 // This might be sped up with a cache of the last generation that
833 // answered yes.
834 if (_young_gen->is_in(p) || _old_gen->is_in(p)) {
835 return true;
836 }
837 // Otherwise...
838 return false;
839 }
840
841 #ifdef ASSERT
842 // Don't implement this by using is_in_young(). This method is used
843 // in some cases to check that is_in_young() is correct.
844 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
845 assert(is_in_reserved(p) || p == NULL,
846 "Does not work if address is non-null and outside of the heap");
847 return p < _young_gen->reserved().end() && p != NULL;
848 }
849 #endif
850
851 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
852 _young_gen->oop_iterate(cl);
853 _old_gen->oop_iterate(cl);
854 }
855
856 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
857 _young_gen->object_iterate(cl);
858 _old_gen->object_iterate(cl);
859 }
860
861 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
862 _young_gen->safe_object_iterate(cl);
863 _old_gen->safe_object_iterate(cl);
864 }
865
866 Space* GenCollectedHeap::space_containing(const void* addr) const {
867 Space* res = _young_gen->space_containing(addr);
868 if (res != NULL) {
869 return res;
870 }
871 res = _old_gen->space_containing(addr);
872 assert(res != NULL, "Could not find containing space");
873 return res;
874 }
875
876 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
877 assert(is_in_reserved(addr), "block_start of address outside of heap");
878 if (_young_gen->is_in_reserved(addr)) {
879 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
880 return _young_gen->block_start(addr);
881 }
882
883 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
884 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
885 return _old_gen->block_start(addr);
886 }
887
888 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
889 assert(is_in_reserved(addr), "block_size of address outside of heap");
890 if (_young_gen->is_in_reserved(addr)) {
891 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
892 return _young_gen->block_size(addr);
893 }
894
895 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
896 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
897 return _old_gen->block_size(addr);
898 }
899
900 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
901 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
902 assert(block_start(addr) == addr, "addr must be a block start");
903 if (_young_gen->is_in_reserved(addr)) {
904 return _young_gen->block_is_obj(addr);
905 }
906
907 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
908 return _old_gen->block_is_obj(addr);
909 }
910
911 bool GenCollectedHeap::supports_tlab_allocation() const {
912 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
913 return _young_gen->supports_tlab_allocation();
914 }
915
916 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
917 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
918 if (_young_gen->supports_tlab_allocation()) {
919 return _young_gen->tlab_capacity();
920 }
921 return 0;
922 }
923
924 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
925 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
926 if (_young_gen->supports_tlab_allocation()) {
927 return _young_gen->tlab_used();
928 }
929 return 0;
930 }
931
932 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
933 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
934 if (_young_gen->supports_tlab_allocation()) {
935 return _young_gen->unsafe_max_tlab_alloc();
936 }
937 return 0;
938 }
939
940 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
941 bool gc_overhead_limit_was_exceeded;
942 return collector_policy()->mem_allocate_work(size /* size */,
943 true /* is_tlab */,
944 &gc_overhead_limit_was_exceeded);
945 }
946
947 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
948 // from the list headed by "*prev_ptr".
949 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
950 bool first = true;
951 size_t min_size = 0; // "first" makes this conceptually infinite.
952 ScratchBlock **smallest_ptr, *smallest;
953 ScratchBlock *cur = *prev_ptr;
954 while (cur) {
955 assert(*prev_ptr == cur, "just checking");
956 if (first || cur->num_words < min_size) {
957 smallest_ptr = prev_ptr;
958 smallest = cur;
959 min_size = smallest->num_words;
960 first = false;
961 }
962 prev_ptr = &cur->next;
963 cur = cur->next;
964 }
965 smallest = *smallest_ptr;
966 *smallest_ptr = smallest->next;
967 return smallest;
968 }
969
970 // Sort the scratch block list headed by res into decreasing size order,
971 // and set "res" to the result.
972 static void sort_scratch_list(ScratchBlock*& list) {
973 ScratchBlock* sorted = NULL;
974 ScratchBlock* unsorted = list;
975 while (unsorted) {
976 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
977 smallest->next = sorted;
978 sorted = smallest;
979 }
980 list = sorted;
981 }
982
983 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
984 size_t max_alloc_words) {
985 ScratchBlock* res = NULL;
986 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
987 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
988 sort_scratch_list(res);
989 return res;
990 }
991
992 void GenCollectedHeap::release_scratch() {
993 _young_gen->reset_scratch();
994 _old_gen->reset_scratch();
995 }
996
997 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
998 void do_generation(Generation* gen) {
999 gen->prepare_for_verify();
1000 }
1001 };
1002
1003 void GenCollectedHeap::prepare_for_verify() {
1004 ensure_parsability(false); // no need to retire TLABs
1005 GenPrepareForVerifyClosure blk;
1006 generation_iterate(&blk, false);
1007 }
1008
1009 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1010 bool old_to_young) {
1011 if (old_to_young) {
1012 cl->do_generation(_old_gen);
1013 cl->do_generation(_young_gen);
1014 } else {
1015 cl->do_generation(_young_gen);
1016 cl->do_generation(_old_gen);
1017 }
1018 }
1019
1020 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1021 _young_gen->space_iterate(cl, true);
1022 _old_gen->space_iterate(cl, true);
1023 }
1024
1025 bool GenCollectedHeap::is_maximal_no_gc() const {
1026 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1027 }
1028
1029 void GenCollectedHeap::save_marks() {
1030 _young_gen->save_marks();
1031 _old_gen->save_marks();
1032 }
1033
1034 GenCollectedHeap* GenCollectedHeap::heap() {
1035 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1036 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1037 return _gch;
1038 }
1039
1040
1041 void GenCollectedHeap::prepare_for_compaction() {
1042 guarantee(_n_gens = 2, "Wrong number of generations");
1043 // Start by compacting into same gen.
1044 CompactPoint cp(_old_gen);
1045 _old_gen->prepare_for_compaction(&cp);
1046 _young_gen->prepare_for_compaction(&cp);
1047 }
1048
1049 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1050 if (!silent) {
1051 gclog_or_tty->print("%s", _old_gen->name());
1052 gclog_or_tty->print(" ");
1053 }
1054 _old_gen->verify();
1055
1056 if (!silent) {
1057 gclog_or_tty->print("%s", _young_gen->name());
1058 gclog_or_tty->print(" ");
1059 }
1060 _young_gen->verify();
1061
1062 if (!silent) {
1063 gclog_or_tty->print("remset ");
1064 }
1065 rem_set()->verify();
1066 }
1067
1068 void GenCollectedHeap::print_on(outputStream* st) const {
1069 _young_gen->print_on(st);
1070 _old_gen->print_on(st);
1071 MetaspaceAux::print_on(st);
1072 }
1073
1074 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1075 if (workers() != NULL) {
1076 workers()->threads_do(tc);
1077 }
1078 #if INCLUDE_ALL_GCS
1079 if (UseConcMarkSweepGC) {
1080 ConcurrentMarkSweepThread::threads_do(tc);
1081 }
1082 #endif // INCLUDE_ALL_GCS
1083 }
1084
1085 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1086 #if INCLUDE_ALL_GCS
1087 if (UseParNewGC) {
1088 workers()->print_worker_threads_on(st);
1089 }
1090 if (UseConcMarkSweepGC) {
1091 ConcurrentMarkSweepThread::print_all_on(st);
1092 }
1093 #endif // INCLUDE_ALL_GCS
1094 }
1095
1096 void GenCollectedHeap::print_on_error(outputStream* st) const {
1097 this->CollectedHeap::print_on_error(st);
1098
1099 #if INCLUDE_ALL_GCS
1100 if (UseConcMarkSweepGC) {
1101 st->cr();
1102 CMSCollector::print_on_error(st);
1103 }
1104 #endif // INCLUDE_ALL_GCS
1105 }
1106
1107 void GenCollectedHeap::print_tracing_info() const {
1108 if (TraceYoungGenTime) {
1109 _young_gen->print_summary_info();
1110 }
1111 if (TraceOldGenTime) {
1112 _old_gen->print_summary_info();
1113 }
1114 }
1115
1116 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1117 if (PrintGCDetails && Verbose) {
1118 gclog_or_tty->print(" " SIZE_FORMAT
1119 "->" SIZE_FORMAT
1120 "(" SIZE_FORMAT ")",
1121 prev_used, used(), capacity());
1122 } else {
1123 gclog_or_tty->print(" " SIZE_FORMAT "K"
1124 "->" SIZE_FORMAT "K"
1125 "(" SIZE_FORMAT "K)",
1126 prev_used / K, used() / K, capacity() / K);
1127 }
1128 }
1129
1130 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1131 private:
1132 bool _full;
1133 public:
1134 void do_generation(Generation* gen) {
1135 gen->gc_prologue(_full);
1136 }
1137 GenGCPrologueClosure(bool full) : _full(full) {};
1138 };
1139
1140 void GenCollectedHeap::gc_prologue(bool full) {
1141 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1142
1143 always_do_update_barrier = false;
1144 // Fill TLAB's and such
1145 CollectedHeap::accumulate_statistics_all_tlabs();
1146 ensure_parsability(true); // retire TLABs
1147
1148 // Walk generations
1149 GenGCPrologueClosure blk(full);
1150 generation_iterate(&blk, false); // not old-to-young.
1151 };
1152
1153 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1154 private:
1155 bool _full;
1156 public:
1157 void do_generation(Generation* gen) {
1158 gen->gc_epilogue(_full);
1159 }
1160 GenGCEpilogueClosure(bool full) : _full(full) {};
1161 };
1162
1163 void GenCollectedHeap::gc_epilogue(bool full) {
1164 #ifdef COMPILER2
1165 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1166 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1167 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1168 #endif /* COMPILER2 */
1169
1170 resize_all_tlabs();
1171
1172 GenGCEpilogueClosure blk(full);
1173 generation_iterate(&blk, false); // not old-to-young.
1174
1175 if (!CleanChunkPoolAsync) {
1176 Chunk::clean_chunk_pool();
1177 }
1178
1179 MetaspaceCounters::update_performance_counters();
1180 CompressedClassSpaceCounters::update_performance_counters();
1181
1182 always_do_update_barrier = UseConcMarkSweepGC;
1183 };
1184
1185 #ifndef PRODUCT
1186 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1187 private:
1188 public:
1189 void do_generation(Generation* gen) {
1190 gen->record_spaces_top();
1191 }
1192 };
1193
1194 void GenCollectedHeap::record_gen_tops_before_GC() {
1195 if (ZapUnusedHeapArea) {
1196 GenGCSaveTopsBeforeGCClosure blk;
1197 generation_iterate(&blk, false); // not old-to-young.
1198 }
1199 }
1200 #endif // not PRODUCT
1201
1202 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1203 public:
1204 void do_generation(Generation* gen) {
1205 gen->ensure_parsability();
1206 }
1207 };
1208
1209 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1210 CollectedHeap::ensure_parsability(retire_tlabs);
1211 GenEnsureParsabilityClosure ep_cl;
1212 generation_iterate(&ep_cl, false);
1213 }
1214
1215 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1216 oop obj,
1217 size_t obj_size) {
1218 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1219 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1220 HeapWord* result = NULL;
1221
1222 result = old_gen->expand_and_allocate(obj_size, false);
1223
1224 if (result != NULL) {
1225 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1226 }
1227 return oop(result);
1228 }
1229
1230 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1231 jlong _time; // in ms
1232 jlong _now; // in ms
1233
1234 public:
1235 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1236
1237 jlong time() { return _time; }
1238
1239 void do_generation(Generation* gen) {
1240 _time = MIN2(_time, gen->time_of_last_gc(_now));
1241 }
1242 };
1243
1244 jlong GenCollectedHeap::millis_since_last_gc() {
1245 // We need a monotonically non-decreasing time in ms but
1246 // os::javaTimeMillis() does not guarantee monotonicity.
1247 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1248 GenTimeOfLastGCClosure tolgc_cl(now);
1249 // iterate over generations getting the oldest
1250 // time that a generation was collected
1251 generation_iterate(&tolgc_cl, false);
1252
1253 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1254 // provided the underlying platform provides such a time source
1255 // (and it is bug free). So we still have to guard against getting
1256 // back a time later than 'now'.
1257 jlong retVal = now - tolgc_cl.time();
1258 if (retVal < 0) {
1259 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1260 return 0;
1261 }
1262 return retVal;
1263 }