1 /*
2 * Copyright (c) 2000, 2017, 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 "aot/aotLoader.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "gc/shared/collectedHeap.inline.hpp"
33 #include "gc/shared/collectorCounters.hpp"
34 #include "gc/shared/gcId.hpp"
35 #include "gc/shared/gcLocker.inline.hpp"
36 #include "gc/shared/gcTrace.hpp"
37 #include "gc/shared/gcTraceTime.inline.hpp"
38 #include "gc/shared/genCollectedHeap.hpp"
39 #include "gc/shared/genOopClosures.inline.hpp"
40 #include "gc/shared/generationSpec.hpp"
41 #include "gc/shared/space.hpp"
42 #include "gc/shared/strongRootsScope.hpp"
43 #include "gc/shared/vmGCOperations.hpp"
44 #include "gc/shared/workgroup.hpp"
45 #include "memory/filemap.hpp"
46 #include "memory/resourceArea.hpp"
47 #include "oops/oop.inline.hpp"
48 #include "runtime/biasedLocking.hpp"
49 #include "runtime/fprofiler.hpp"
50 #include "runtime/handles.hpp"
51 #include "runtime/handles.inline.hpp"
52 #include "runtime/java.hpp"
53 #include "runtime/vmThread.hpp"
54 #include "services/management.hpp"
55 #include "services/memoryService.hpp"
56 #include "utilities/debug.hpp"
57 #include "utilities/formatBuffer.hpp"
58 #include "utilities/macros.hpp"
59 #include "utilities/stack.inline.hpp"
60 #include "utilities/vmError.hpp"
61
62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
63
64 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
65 CollectedHeap(),
66 _rem_set(NULL),
67 _gen_policy(policy),
68 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
69 _full_collections_completed(0)
70 {
71 assert(policy != NULL, "Sanity check");
72 }
73
74 jint GenCollectedHeap::initialize() {
75 CollectedHeap::pre_initialize();
76
77 // While there are no constraints in the GC code that HeapWordSize
78 // be any particular value, there are multiple other areas in the
79 // system which believe this to be true (e.g. oop->object_size in some
80 // cases incorrectly returns the size in wordSize units rather than
81 // HeapWordSize).
82 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
83
84 // Allocate space for the heap.
85
86 char* heap_address;
87 ReservedSpace heap_rs;
88
89 size_t heap_alignment = collector_policy()->heap_alignment();
90
91 heap_address = allocate(heap_alignment, &heap_rs);
92
93 if (!heap_rs.is_reserved()) {
94 vm_shutdown_during_initialization(
95 "Could not reserve enough space for object heap");
96 return JNI_ENOMEM;
97 }
98
99 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
100
101 _rem_set = collector_policy()->create_rem_set(reserved_region());
102 set_barrier_set(rem_set()->bs());
103
104 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
105 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
106 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
107
108 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
109 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
110 clear_incremental_collection_failed();
111
112 return JNI_OK;
113 }
114
115 char* GenCollectedHeap::allocate(size_t alignment,
116 ReservedSpace* heap_rs){
117 // Now figure out the total size.
118 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
119 assert(alignment % pageSize == 0, "Must be");
120
121 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
122 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
123
124 // Check for overflow.
125 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
126 if (total_reserved < young_spec->max_size()) {
127 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
128 "the maximum representable size");
129 }
130 assert(total_reserved % alignment == 0,
131 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
132 SIZE_FORMAT, total_reserved, alignment);
133
134 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
135
136 os::trace_page_sizes("Heap",
137 collector_policy()->min_heap_byte_size(),
138 total_reserved,
139 alignment,
140 heap_rs->base(),
141 heap_rs->size());
142
143 return heap_rs->base();
144 }
145
146 void GenCollectedHeap::post_initialize() {
147 ref_processing_init();
148 #ifdef ASSERT
149 check_gen_kinds();
150 #endif
151 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
152
153 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
154 _old_gen->capacity(),
155 def_new_gen->from()->capacity());
156 _gen_policy->initialize_gc_policy_counters();
157 }
158
159 #ifdef ASSERT
160 void GenCollectedHeap::check_gen_kinds() {
161 assert(young_gen()->kind() == Generation::DefNew,
162 "Wrong youngest generation type");
163 assert(old_gen()->kind() == Generation::MarkSweepCompact,
164 "Wrong generation kind");
165 }
166 #endif
167
168 void GenCollectedHeap::ref_processing_init() {
169 _young_gen->ref_processor_init();
170 _old_gen->ref_processor_init();
171 }
172
173 size_t GenCollectedHeap::capacity() const {
174 return _young_gen->capacity() + _old_gen->capacity();
175 }
176
177 size_t GenCollectedHeap::used() const {
178 return _young_gen->used() + _old_gen->used();
179 }
180
181 void GenCollectedHeap::save_used_regions() {
182 _old_gen->save_used_region();
183 _young_gen->save_used_region();
184 }
185
186 size_t GenCollectedHeap::max_capacity() const {
187 return _young_gen->max_capacity() + _old_gen->max_capacity();
188 }
189
190 // Update the _full_collections_completed counter
191 // at the end of a stop-world full GC.
192 unsigned int GenCollectedHeap::update_full_collections_completed() {
193 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
194 assert(_full_collections_completed <= _total_full_collections,
195 "Can't complete more collections than were started");
196 _full_collections_completed = _total_full_collections;
197 ml.notify_all();
198 return _full_collections_completed;
199 }
200
201 // Update the _full_collections_completed counter, as appropriate,
202 // at the end of a concurrent GC cycle. Note the conditional update
203 // below to allow this method to be called by a concurrent collector
204 // without synchronizing in any manner with the VM thread (which
205 // may already have initiated a STW full collection "concurrently").
206 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
207 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
208 assert((_full_collections_completed <= _total_full_collections) &&
209 (count <= _total_full_collections),
210 "Can't complete more collections than were started");
211 if (count > _full_collections_completed) {
212 _full_collections_completed = count;
213 ml.notify_all();
214 }
215 return _full_collections_completed;
216 }
217
218
219 #ifndef PRODUCT
220 // Override of memory state checking method in CollectedHeap:
221 // Some collectors (CMS for example) can't have badHeapWordVal written
222 // in the first two words of an object. (For instance , in the case of
223 // CMS these words hold state used to synchronize between certain
224 // (concurrent) GC steps and direct allocating mutators.)
225 // The skip_header_HeapWords() method below, allows us to skip
226 // over the requisite number of HeapWord's. Note that (for
227 // generational collectors) this means that those many words are
228 // skipped in each object, irrespective of the generation in which
229 // that object lives. The resultant loss of precision seems to be
230 // harmless and the pain of avoiding that imprecision appears somewhat
231 // higher than we are prepared to pay for such rudimentary debugging
232 // support.
233 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
234 size_t size) {
235 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
236 // We are asked to check a size in HeapWords,
237 // but the memory is mangled in juint words.
238 juint* start = (juint*) (addr + skip_header_HeapWords());
239 juint* end = (juint*) (addr + size);
240 for (juint* slot = start; slot < end; slot += 1) {
241 assert(*slot == badHeapWordVal,
242 "Found non badHeapWordValue in pre-allocation check");
243 }
244 }
245 }
246 #endif
247
248 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
249 bool is_tlab,
250 bool first_only) {
251 HeapWord* res = NULL;
252
253 if (_young_gen->should_allocate(size, is_tlab)) {
254 res = _young_gen->allocate(size, is_tlab);
255 if (res != NULL || first_only) {
256 return res;
257 }
258 }
259
260 if (_old_gen->should_allocate(size, is_tlab)) {
261 res = _old_gen->allocate(size, is_tlab);
262 }
263
264 return res;
265 }
266
267 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
268 bool* gc_overhead_limit_was_exceeded) {
269 return gen_policy()->mem_allocate_work(size,
270 false /* is_tlab */,
271 gc_overhead_limit_was_exceeded);
272 }
273
274 bool GenCollectedHeap::must_clear_all_soft_refs() {
275 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
276 _gc_cause == GCCause::_wb_full_gc;
277 }
278
279 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
280 bool is_tlab, bool run_verification, bool clear_soft_refs,
281 bool restore_marks_for_biased_locking) {
282 FormatBuffer<> title("Collect gen: %s", gen->short_name());
283 GCTraceTime(Trace, gc, phases) t1(title);
284 TraceCollectorStats tcs(gen->counters());
285 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
286
287 gen->stat_record()->invocations++;
288 gen->stat_record()->accumulated_time.start();
289
290 // Must be done anew before each collection because
291 // a previous collection will do mangling and will
292 // change top of some spaces.
293 record_gen_tops_before_GC();
294
295 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
296
297 if (run_verification && VerifyBeforeGC) {
298 HandleMark hm; // Discard invalid handles created during verification
299 Universe::verify("Before GC");
300 }
301 COMPILER2_PRESENT(DerivedPointerTable::clear());
302
303 if (restore_marks_for_biased_locking) {
304 // We perform this mark word preservation work lazily
305 // because it's only at this point that we know whether we
306 // absolutely have to do it; we want to avoid doing it for
307 // scavenge-only collections where it's unnecessary
308 BiasedLocking::preserve_marks();
309 }
310
311 // Do collection work
312 {
313 // Note on ref discovery: For what appear to be historical reasons,
314 // GCH enables and disabled (by enqueing) refs discovery.
315 // In the future this should be moved into the generation's
316 // collect method so that ref discovery and enqueueing concerns
317 // are local to a generation. The collect method could return
318 // an appropriate indication in the case that notification on
319 // the ref lock was needed. This will make the treatment of
320 // weak refs more uniform (and indeed remove such concerns
321 // from GCH). XXX
322
323 HandleMark hm; // Discard invalid handles created during gc
324 save_marks(); // save marks for all gens
325 // We want to discover references, but not process them yet.
326 // This mode is disabled in process_discovered_references if the
327 // generation does some collection work, or in
328 // enqueue_discovered_references if the generation returns
329 // without doing any work.
330 ReferenceProcessor* rp = gen->ref_processor();
331 // If the discovery of ("weak") refs in this generation is
332 // atomic wrt other collectors in this configuration, we
333 // are guaranteed to have empty discovered ref lists.
334 if (rp->discovery_is_atomic()) {
335 rp->enable_discovery();
336 rp->setup_policy(clear_soft_refs);
337 } else {
338 // collect() below will enable discovery as appropriate
339 }
340 gen->collect(full, clear_soft_refs, size, is_tlab);
341 if (!rp->enqueuing_is_done()) {
342 rp->enqueue_discovered_references();
343 } else {
344 rp->set_enqueuing_is_done(false);
345 }
346 rp->verify_no_references_recorded();
347 }
348
349 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
350
351 gen->stat_record()->accumulated_time.stop();
352
353 update_gc_stats(gen, full);
354
355 if (run_verification && VerifyAfterGC) {
356 HandleMark hm; // Discard invalid handles created during verification
357 Universe::verify("After GC");
358 }
359 }
360
361 void GenCollectedHeap::do_collection(bool full,
362 bool clear_all_soft_refs,
363 size_t size,
364 bool is_tlab,
365 GenerationType max_generation) {
366 ResourceMark rm;
367 DEBUG_ONLY(Thread* my_thread = Thread::current();)
368
369 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
370 assert(my_thread->is_VM_thread() ||
371 my_thread->is_ConcurrentGC_thread(),
372 "incorrect thread type capability");
373 assert(Heap_lock->is_locked(),
374 "the requesting thread should have the Heap_lock");
375 guarantee(!is_gc_active(), "collection is not reentrant");
376
377 if (GCLocker::check_active_before_gc()) {
378 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
379 }
380
381 GCIdMarkAndRestore gc_id_mark;
382
383 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
384 collector_policy()->should_clear_all_soft_refs();
385
386 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
387
388 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
389
390 print_heap_before_gc();
391
392 {
393 FlagSetting fl(_is_gc_active, true);
394
395 bool complete = full && (max_generation == OldGen);
396 bool old_collects_young = complete && !ScavengeBeforeFullGC;
397 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
398
399 FormatBuffer<> gc_string("%s", "Pause ");
400 if (do_young_collection) {
401 gc_string.append("Young");
402 } else {
403 gc_string.append("Full");
404 }
405
406 GCTraceCPUTime tcpu;
407 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
408
409 gc_prologue(complete);
410 increment_total_collections(complete);
411
412 size_t young_prev_used = _young_gen->used();
413 size_t old_prev_used = _old_gen->used();
414
415 bool run_verification = total_collections() >= VerifyGCStartAt;
416
417 bool prepared_for_verification = false;
418 bool collected_old = false;
419
420 if (do_young_collection) {
421 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
422 prepare_for_verify();
423 prepared_for_verification = true;
424 }
425
426 collect_generation(_young_gen,
427 full,
428 size,
429 is_tlab,
430 run_verification && VerifyGCLevel <= 0,
431 do_clear_all_soft_refs,
432 false);
433
434 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
435 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
436 // Allocation request was met by young GC.
437 size = 0;
438 }
439 }
440
441 bool must_restore_marks_for_biased_locking = false;
442
443 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
444 if (!complete) {
445 // The full_collections increment was missed above.
446 increment_total_full_collections();
447 }
448
449 if (!prepared_for_verification && run_verification &&
450 VerifyGCLevel <= 1 && VerifyBeforeGC) {
451 prepare_for_verify();
452 }
453
454 if (do_young_collection) {
455 // We did a young GC. Need a new GC id for the old GC.
456 GCIdMarkAndRestore gc_id_mark;
457 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
458 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
459 } else {
460 // No young GC done. Use the same GC id as was set up earlier in this method.
461 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
462 }
463
464 must_restore_marks_for_biased_locking = true;
465 collected_old = true;
466 }
467
468 // Update "complete" boolean wrt what actually transpired --
469 // for instance, a promotion failure could have led to
470 // a whole heap collection.
471 complete = complete || collected_old;
472
473 print_heap_change(young_prev_used, old_prev_used);
474 MetaspaceAux::print_metaspace_change(metadata_prev_used);
475
476 // Adjust generation sizes.
477 if (collected_old) {
478 _old_gen->compute_new_size();
479 }
480 _young_gen->compute_new_size();
481
482 if (complete) {
483 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
484 ClassLoaderDataGraph::purge();
485 MetaspaceAux::verify_metrics();
486 // Resize the metaspace capacity after full collections
487 MetaspaceGC::compute_new_size();
488 update_full_collections_completed();
489 }
490
491 // Track memory usage and detect low memory after GC finishes
492 MemoryService::track_memory_usage();
493
494 gc_epilogue(complete);
495
496 if (must_restore_marks_for_biased_locking) {
497 BiasedLocking::restore_marks();
498 }
499 }
500
501 print_heap_after_gc();
502
503 #ifdef TRACESPINNING
504 ParallelTaskTerminator::print_termination_counts();
505 #endif
506 }
507
508 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
509 return gen_policy()->satisfy_failed_allocation(size, is_tlab);
510 }
511
512 #ifdef ASSERT
513 class AssertNonScavengableClosure: public OopClosure {
514 public:
515 virtual void do_oop(oop* p) {
516 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
517 "Referent should not be scavengable."); }
518 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
519 };
520 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
521 #endif
522
523 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
524 ScanningOption so,
525 OopClosure* strong_roots,
526 OopClosure* weak_roots,
527 CLDClosure* strong_cld_closure,
528 CLDClosure* weak_cld_closure,
529 CodeBlobToOopClosure* code_roots) {
530 // General roots.
531 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
532 assert(code_roots != NULL, "code root closure should always be set");
533 // _n_termination for _process_strong_tasks should be set up stream
534 // in a method not running in a GC worker. Otherwise the GC worker
535 // could be trying to change the termination condition while the task
536 // is executing in another GC worker.
537
538 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
539 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
540 }
541
542 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
543 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
544
545 bool is_par = scope->n_threads() > 1;
546 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
547
548 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
549 Universe::oops_do(strong_roots);
550 }
551 // Global (strong) JNI handles
552 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
553 JNIHandles::oops_do(strong_roots);
554 }
555
556 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
557 ObjectSynchronizer::oops_do(strong_roots);
558 }
559 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
560 FlatProfiler::oops_do(strong_roots);
561 }
562 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
563 Management::oops_do(strong_roots);
564 }
565 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
566 JvmtiExport::oops_do(strong_roots);
567 }
568 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
569 AOTLoader::oops_do(strong_roots);
570 }
571
572 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
573 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
574 }
575
576 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
577 if (so & SO_ScavengeCodeCache) {
578 assert(code_roots != NULL, "must supply closure for code cache");
579
580 // We only visit parts of the CodeCache when scavenging.
581 CodeCache::scavenge_root_nmethods_do(code_roots);
582 }
583 if (so & SO_AllCodeCache) {
584 assert(code_roots != NULL, "must supply closure for code cache");
585
586 // CMSCollector uses this to do intermediate-strength collections.
587 // We scan the entire code cache, since CodeCache::do_unloading is not called.
588 CodeCache::blobs_do(code_roots);
589 }
590 // Verify that the code cache contents are not subject to
591 // movement by a scavenging collection.
592 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
593 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
594 }
595 }
596
597 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
598 OopClosure* root_closure) {
599 assert(root_closure != NULL, "Must be set");
600 // All threads execute the following. A specific chunk of buckets
601 // from the StringTable are the individual tasks.
602 if (scope->n_threads() > 1) {
603 StringTable::possibly_parallel_oops_do(root_closure);
604 } else {
605 StringTable::oops_do(root_closure);
606 }
607 }
608
609 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
610 OopsInGenClosure* root_closure,
611 OopsInGenClosure* old_gen_closure,
612 CLDClosure* cld_closure) {
613 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
614
615 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
616 cld_closure, cld_closure, &mark_code_closure);
617 process_string_table_roots(scope, root_closure);
618
619 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
620 root_closure->reset_generation();
621 }
622
623 // When collection is parallel, all threads get to cooperate to do
624 // old generation scanning.
625 old_gen_closure->set_generation(_old_gen);
626 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
627 old_gen_closure->reset_generation();
628
629 _process_strong_tasks->all_tasks_completed(scope->n_threads());
630 }
631
632 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
633 bool is_adjust_phase,
634 ScanningOption so,
635 bool only_strong_roots,
636 OopsInGenClosure* root_closure,
637 CLDClosure* cld_closure) {
638 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
639 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
640 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
641
642 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
643 if (is_adjust_phase) {
644 // We never treat the string table as roots during marking
645 // for the full gc, so we only need to process it during
646 // the adjust phase.
647 process_string_table_roots(scope, root_closure);
648 }
649
650 _process_strong_tasks->all_tasks_completed(scope->n_threads());
651 }
652
653 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
654 JNIHandles::weak_oops_do(root_closure);
655 _young_gen->ref_processor()->weak_oops_do(root_closure);
656 _old_gen->ref_processor()->weak_oops_do(root_closure);
657 }
658
659 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
660 void GenCollectedHeap:: \
661 oop_since_save_marks_iterate(GenerationType gen, \
662 OopClosureType* cur, \
663 OopClosureType* older) { \
664 if (gen == YoungGen) { \
665 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
666 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
667 } else { \
668 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
669 } \
670 }
671
672 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
673
674 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
675
676 bool GenCollectedHeap::no_allocs_since_save_marks() {
677 return _young_gen->no_allocs_since_save_marks() &&
678 _old_gen->no_allocs_since_save_marks();
679 }
680
681 bool GenCollectedHeap::supports_inline_contig_alloc() const {
682 return _young_gen->supports_inline_contig_alloc();
683 }
684
685 HeapWord* volatile* GenCollectedHeap::top_addr() const {
686 return _young_gen->top_addr();
687 }
688
689 HeapWord** GenCollectedHeap::end_addr() const {
690 return _young_gen->end_addr();
691 }
692
693 // public collection interfaces
694
695 void GenCollectedHeap::collect(GCCause::Cause cause) {
696 if (cause == GCCause::_wb_young_gc) {
697 // Young collection for the WhiteBox API.
698 collect(cause, YoungGen);
699 } else {
700 #ifdef ASSERT
701 if (cause == GCCause::_scavenge_alot) {
702 // Young collection only.
703 collect(cause, YoungGen);
704 } else {
705 // Stop-the-world full collection.
706 collect(cause, OldGen);
707 }
708 #else
709 // Stop-the-world full collection.
710 collect(cause, OldGen);
711 #endif
712 }
713 }
714
715 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
716 // The caller doesn't have the Heap_lock
717 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
718 MutexLocker ml(Heap_lock);
719 collect_locked(cause, max_generation);
720 }
721
722 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
723 // The caller has the Heap_lock
724 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
725 collect_locked(cause, OldGen);
726 }
727
728 // this is the private collection interface
729 // The Heap_lock is expected to be held on entry.
730
731 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
732 // Read the GC count while holding the Heap_lock
733 unsigned int gc_count_before = total_collections();
734 unsigned int full_gc_count_before = total_full_collections();
735 {
736 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
737 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
738 cause, max_generation);
739 VMThread::execute(&op);
740 }
741 }
742
743 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
744 do_full_collection(clear_all_soft_refs, OldGen);
745 }
746
747 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
748 GenerationType last_generation) {
749 GenerationType local_last_generation;
750 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
751 gc_cause() == GCCause::_gc_locker) {
752 local_last_generation = YoungGen;
753 } else {
754 local_last_generation = last_generation;
755 }
756
757 do_collection(true, // full
758 clear_all_soft_refs, // clear_all_soft_refs
759 0, // size
760 false, // is_tlab
761 local_last_generation); // last_generation
762 // Hack XXX FIX ME !!!
763 // A scavenge may not have been attempted, or may have
764 // been attempted and failed, because the old gen was too full
765 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
766 incremental_collection_will_fail(false /* don't consult_young */)) {
767 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
768 // This time allow the old gen to be collected as well
769 do_collection(true, // full
770 clear_all_soft_refs, // clear_all_soft_refs
771 0, // size
772 false, // is_tlab
773 OldGen); // last_generation
774 }
775 }
776
777 bool GenCollectedHeap::is_in_young(oop p) {
778 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
779 assert(result == _young_gen->is_in_reserved(p),
780 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
781 return result;
782 }
783
784 // Returns "TRUE" iff "p" points into the committed areas of the heap.
785 bool GenCollectedHeap::is_in(const void* p) const {
786 return _young_gen->is_in(p) || _old_gen->is_in(p);
787 }
788
789 #ifdef ASSERT
790 // Don't implement this by using is_in_young(). This method is used
791 // in some cases to check that is_in_young() is correct.
792 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
793 assert(is_in_reserved(p) || p == NULL,
794 "Does not work if address is non-null and outside of the heap");
795 return p < _young_gen->reserved().end() && p != NULL;
796 }
797 #endif
798
799 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
800 NoHeaderExtendedOopClosure no_header_cl(cl);
801 oop_iterate(&no_header_cl);
802 }
803
804 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
805 _young_gen->oop_iterate(cl);
806 _old_gen->oop_iterate(cl);
807 }
808
809 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
810 _young_gen->object_iterate(cl);
811 _old_gen->object_iterate(cl);
812 }
813
814 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
815 _young_gen->safe_object_iterate(cl);
816 _old_gen->safe_object_iterate(cl);
817 }
818
819 Space* GenCollectedHeap::space_containing(const void* addr) const {
820 Space* res = _young_gen->space_containing(addr);
821 if (res != NULL) {
822 return res;
823 }
824 res = _old_gen->space_containing(addr);
825 assert(res != NULL, "Could not find containing space");
826 return res;
827 }
828
829 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
830 assert(is_in_reserved(addr), "block_start of address outside of heap");
831 if (_young_gen->is_in_reserved(addr)) {
832 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
833 return _young_gen->block_start(addr);
834 }
835
836 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
837 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
838 return _old_gen->block_start(addr);
839 }
840
841 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
842 assert(is_in_reserved(addr), "block_size of address outside of heap");
843 if (_young_gen->is_in_reserved(addr)) {
844 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
845 return _young_gen->block_size(addr);
846 }
847
848 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
849 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
850 return _old_gen->block_size(addr);
851 }
852
853 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
854 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
855 assert(block_start(addr) == addr, "addr must be a block start");
856 if (_young_gen->is_in_reserved(addr)) {
857 return _young_gen->block_is_obj(addr);
858 }
859
860 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
861 return _old_gen->block_is_obj(addr);
862 }
863
864 bool GenCollectedHeap::supports_tlab_allocation() const {
865 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
866 return _young_gen->supports_tlab_allocation();
867 }
868
869 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
870 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
871 if (_young_gen->supports_tlab_allocation()) {
872 return _young_gen->tlab_capacity();
873 }
874 return 0;
875 }
876
877 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
878 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
879 if (_young_gen->supports_tlab_allocation()) {
880 return _young_gen->tlab_used();
881 }
882 return 0;
883 }
884
885 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
886 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
887 if (_young_gen->supports_tlab_allocation()) {
888 return _young_gen->unsafe_max_tlab_alloc();
889 }
890 return 0;
891 }
892
893 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
894 bool gc_overhead_limit_was_exceeded;
895 return gen_policy()->mem_allocate_work(size /* size */,
896 true /* is_tlab */,
897 &gc_overhead_limit_was_exceeded);
898 }
899
900 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
901 // from the list headed by "*prev_ptr".
902 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
903 bool first = true;
904 size_t min_size = 0; // "first" makes this conceptually infinite.
905 ScratchBlock **smallest_ptr, *smallest;
906 ScratchBlock *cur = *prev_ptr;
907 while (cur) {
908 assert(*prev_ptr == cur, "just checking");
909 if (first || cur->num_words < min_size) {
910 smallest_ptr = prev_ptr;
911 smallest = cur;
912 min_size = smallest->num_words;
913 first = false;
914 }
915 prev_ptr = &cur->next;
916 cur = cur->next;
917 }
918 smallest = *smallest_ptr;
919 *smallest_ptr = smallest->next;
920 return smallest;
921 }
922
923 // Sort the scratch block list headed by res into decreasing size order,
924 // and set "res" to the result.
925 static void sort_scratch_list(ScratchBlock*& list) {
926 ScratchBlock* sorted = NULL;
927 ScratchBlock* unsorted = list;
928 while (unsorted) {
929 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
930 smallest->next = sorted;
931 sorted = smallest;
932 }
933 list = sorted;
934 }
935
936 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
937 size_t max_alloc_words) {
938 ScratchBlock* res = NULL;
939 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
940 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
941 sort_scratch_list(res);
942 return res;
943 }
944
945 void GenCollectedHeap::release_scratch() {
946 _young_gen->reset_scratch();
947 _old_gen->reset_scratch();
948 }
949
950 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
951 void do_generation(Generation* gen) {
952 gen->prepare_for_verify();
953 }
954 };
955
956 void GenCollectedHeap::prepare_for_verify() {
957 ensure_parsability(false); // no need to retire TLABs
958 GenPrepareForVerifyClosure blk;
959 generation_iterate(&blk, false);
960 }
961
962 void GenCollectedHeap::generation_iterate(GenClosure* cl,
963 bool old_to_young) {
964 if (old_to_young) {
965 cl->do_generation(_old_gen);
966 cl->do_generation(_young_gen);
967 } else {
968 cl->do_generation(_young_gen);
969 cl->do_generation(_old_gen);
970 }
971 }
972
973 bool GenCollectedHeap::is_maximal_no_gc() const {
974 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
975 }
976
977 void GenCollectedHeap::save_marks() {
978 _young_gen->save_marks();
979 _old_gen->save_marks();
980 }
981
982 GenCollectedHeap* GenCollectedHeap::heap() {
983 CollectedHeap* heap = Universe::heap();
984 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
985 assert(heap->kind() == CollectedHeap::GenCollectedHeap ||
986 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap");
987 return (GenCollectedHeap*) heap;
988 }
989
990 void GenCollectedHeap::prepare_for_compaction() {
991 // Start by compacting into same gen.
992 CompactPoint cp(_old_gen);
993 _old_gen->prepare_for_compaction(&cp);
994 _young_gen->prepare_for_compaction(&cp);
995 }
996
997 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
998 log_debug(gc, verify)("%s", _old_gen->name());
999 _old_gen->verify();
1000
1001 log_debug(gc, verify)("%s", _old_gen->name());
1002 _young_gen->verify();
1003
1004 log_debug(gc, verify)("RemSet");
1005 rem_set()->verify();
1006 }
1007
1008 void GenCollectedHeap::print_on(outputStream* st) const {
1009 _young_gen->print_on(st);
1010 _old_gen->print_on(st);
1011 MetaspaceAux::print_on(st);
1012 }
1013
1014 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1015 }
1016
1017 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1018 }
1019
1020 void GenCollectedHeap::print_tracing_info() const {
1021 if (TraceYoungGenTime) {
1022 _young_gen->print_summary_info();
1023 }
1024 if (TraceOldGenTime) {
1025 _old_gen->print_summary_info();
1026 }
1027 }
1028
1029 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1030 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1031 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1032 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1033 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1034 }
1035
1036 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1037 private:
1038 bool _full;
1039 public:
1040 void do_generation(Generation* gen) {
1041 gen->gc_prologue(_full);
1042 }
1043 GenGCPrologueClosure(bool full) : _full(full) {};
1044 };
1045
1046 void GenCollectedHeap::gc_prologue(bool full) {
1047 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1048
1049 always_do_update_barrier = false;
1050 // Fill TLAB's and such
1051 CollectedHeap::accumulate_statistics_all_tlabs();
1052 ensure_parsability(true); // retire TLABs
1053
1054 // Walk generations
1055 GenGCPrologueClosure blk(full);
1056 generation_iterate(&blk, false); // not old-to-young.
1057 };
1058
1059 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1060 private:
1061 bool _full;
1062 public:
1063 void do_generation(Generation* gen) {
1064 gen->gc_epilogue(_full);
1065 }
1066 GenGCEpilogueClosure(bool full) : _full(full) {};
1067 };
1068
1069 void GenCollectedHeap::gc_epilogue(bool full) {
1070 #if defined(COMPILER2) || INCLUDE_JVMCI
1071 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1072 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1073 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1074 #endif /* COMPILER2 || INCLUDE_JVMCI */
1075
1076 resize_all_tlabs();
1077
1078 GenGCEpilogueClosure blk(full);
1079 generation_iterate(&blk, false); // not old-to-young.
1080
1081 if (!CleanChunkPoolAsync) {
1082 Chunk::clean_chunk_pool();
1083 }
1084
1085 MetaspaceCounters::update_performance_counters();
1086 CompressedClassSpaceCounters::update_performance_counters();
1087
1088 always_do_update_barrier = UseConcMarkSweepGC;
1089 };
1090
1091 #ifndef PRODUCT
1092 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1093 private:
1094 public:
1095 void do_generation(Generation* gen) {
1096 gen->record_spaces_top();
1097 }
1098 };
1099
1100 void GenCollectedHeap::record_gen_tops_before_GC() {
1101 if (ZapUnusedHeapArea) {
1102 GenGCSaveTopsBeforeGCClosure blk;
1103 generation_iterate(&blk, false); // not old-to-young.
1104 }
1105 }
1106 #endif // not PRODUCT
1107
1108 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1109 public:
1110 void do_generation(Generation* gen) {
1111 gen->ensure_parsability();
1112 }
1113 };
1114
1115 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1116 CollectedHeap::ensure_parsability(retire_tlabs);
1117 GenEnsureParsabilityClosure ep_cl;
1118 generation_iterate(&ep_cl, false);
1119 }
1120
1121 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1122 oop obj,
1123 size_t obj_size) {
1124 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1125 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1126 HeapWord* result = NULL;
1127
1128 result = old_gen->expand_and_allocate(obj_size, false);
1129
1130 if (result != NULL) {
1131 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1132 }
1133 return oop(result);
1134 }
1135
1136 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1137 jlong _time; // in ms
1138 jlong _now; // in ms
1139
1140 public:
1141 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1142
1143 jlong time() { return _time; }
1144
1145 void do_generation(Generation* gen) {
1146 _time = MIN2(_time, gen->time_of_last_gc(_now));
1147 }
1148 };
1149
1150 jlong GenCollectedHeap::millis_since_last_gc() {
1151 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1152 // provided the underlying platform provides such a time source
1153 // (and it is bug free). So we still have to guard against getting
1154 // back a time later than 'now'.
1155 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1156 GenTimeOfLastGCClosure tolgc_cl(now);
1157 // iterate over generations getting the oldest
1158 // time that a generation was collected
1159 generation_iterate(&tolgc_cl, false);
1160
1161 jlong retVal = now - tolgc_cl.time();
1162 if (retVal < 0) {
1163 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1164 ". returning zero instead.", retVal);
1165 return 0;
1166 }
1167 return retVal;
1168 }