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