1 /*
2 * Copyright (c) 2000, 2016, 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/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/shared/collectedHeap.inline.hpp"
32 #include "gc/shared/collectorCounters.hpp"
33 #include "gc/shared/gcId.hpp"
34 #include "gc/shared/gcLocker.inline.hpp"
35 #include "gc/shared/gcTrace.hpp"
36 #include "gc/shared/gcTraceTime.inline.hpp"
37 #include "gc/shared/genCollectedHeap.hpp"
38 #include "gc/shared/genOopClosures.inline.hpp"
39 #include "gc/shared/generationSpec.hpp"
40 #include "gc/shared/space.hpp"
41 #include "gc/shared/strongRootsScope.hpp"
42 #include "gc/shared/vmGCOperations.hpp"
43 #include "gc/shared/workgroup.hpp"
44 #include "memory/filemap.hpp"
45 #include "memory/resourceArea.hpp"
46 #include "oops/oop.inline.hpp"
47 #include "runtime/biasedLocking.hpp"
48 #include "runtime/fprofiler.hpp"
49 #include "runtime/handles.hpp"
50 #include "runtime/handles.inline.hpp"
51 #include "runtime/java.hpp"
52 #include "runtime/vmThread.hpp"
53 #include "services/management.hpp"
54 #include "services/memoryService.hpp"
55 #include "utilities/macros.hpp"
56 #include "utilities/stack.inline.hpp"
57 #include "utilities/vmError.hpp"
58
59 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
60
61 // The set of potentially parallel tasks in root scanning.
62 enum GCH_strong_roots_tasks {
63 GCH_PS_Universe_oops_do,
64 GCH_PS_JNIHandles_oops_do,
65 GCH_PS_ObjectSynchronizer_oops_do,
66 GCH_PS_FlatProfiler_oops_do,
67 GCH_PS_Management_oops_do,
68 GCH_PS_SystemDictionary_oops_do,
69 GCH_PS_ClassLoaderDataGraph_oops_do,
70 GCH_PS_jvmti_oops_do,
71 GCH_PS_CodeCache_oops_do,
72 GCH_PS_younger_gens,
73 // Leave this one last.
74 GCH_PS_NumElements
75 };
76
77 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
78 CollectedHeap(),
79 _rem_set(NULL),
80 _gen_policy(policy),
81 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
82 _full_collections_completed(0)
83 {
84 assert(policy != NULL, "Sanity check");
85 if (UseConcMarkSweepGC) {
86 _workers = new WorkGang("GC Thread", ParallelGCThreads,
87 /* are_GC_task_threads */true,
88 /* are_ConcurrentGC_threads */false);
89 _workers->initialize_workers();
90 } else {
91 // Serial GC does not use workers.
92 _workers = NULL;
93 }
94 }
95
96 jint GenCollectedHeap::initialize() {
97 CollectedHeap::pre_initialize();
98
99 // While there are no constraints in the GC code that HeapWordSize
100 // be any particular value, there are multiple other areas in the
101 // system which believe this to be true (e.g. oop->object_size in some
102 // cases incorrectly returns the size in wordSize units rather than
103 // HeapWordSize).
104 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
105
106 // Allocate space for the heap.
107
108 char* heap_address;
109 ReservedSpace heap_rs;
110
111 size_t heap_alignment = collector_policy()->heap_alignment();
112
113 heap_address = allocate(heap_alignment, &heap_rs);
114
115 if (!heap_rs.is_reserved()) {
116 vm_shutdown_during_initialization(
117 "Could not reserve enough space for object heap");
118 return JNI_ENOMEM;
119 }
120
121 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
122
123 _rem_set = collector_policy()->create_rem_set(reserved_region());
124 set_barrier_set(rem_set()->bs());
125
126 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
127 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
128 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
129
130 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
131 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
132 clear_incremental_collection_failed();
133
134 return JNI_OK;
135 }
136
137 char* GenCollectedHeap::allocate(size_t alignment,
138 ReservedSpace* heap_rs){
139 // Now figure out the total size.
140 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
141 assert(alignment % pageSize == 0, "Must be");
142
143 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
144 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
145
146 // Check for overflow.
147 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
148 if (total_reserved < young_spec->max_size()) {
149 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
150 "the maximum representable size");
151 }
152 assert(total_reserved % alignment == 0,
153 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
154 SIZE_FORMAT, total_reserved, alignment);
155
156 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
157
158 os::trace_page_sizes("Heap",
159 collector_policy()->min_heap_byte_size(),
160 total_reserved,
161 alignment,
162 heap_rs->base(),
163 heap_rs->size());
164
165 return heap_rs->base();
166 }
167
168 void GenCollectedHeap::post_initialize() {
169 ref_processing_init();
170 assert((_young_gen->kind() == Generation::DefNew) ||
171 (_young_gen->kind() == Generation::ParNew),
172 "Wrong youngest generation type");
173 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
174
175 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
176 _old_gen->kind() == Generation::MarkSweepCompact,
177 "Wrong generation kind");
178
179 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
180 _old_gen->capacity(),
181 def_new_gen->from()->capacity());
182 _gen_policy->initialize_gc_policy_counters();
183 }
184
185 void GenCollectedHeap::ref_processing_init() {
186 _young_gen->ref_processor_init();
187 _old_gen->ref_processor_init();
188 }
189
190 size_t GenCollectedHeap::capacity() const {
191 return _young_gen->capacity() + _old_gen->capacity();
192 }
193
194 size_t GenCollectedHeap::used() const {
195 return _young_gen->used() + _old_gen->used();
196 }
197
198 void GenCollectedHeap::save_used_regions() {
199 _old_gen->save_used_region();
200 _young_gen->save_used_region();
201 }
202
203 size_t GenCollectedHeap::max_capacity() const {
204 return _young_gen->max_capacity() + _old_gen->max_capacity();
205 }
206
207 // Update the _full_collections_completed counter
208 // at the end of a stop-world full GC.
209 unsigned int GenCollectedHeap::update_full_collections_completed() {
210 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
211 assert(_full_collections_completed <= _total_full_collections,
212 "Can't complete more collections than were started");
213 _full_collections_completed = _total_full_collections;
214 ml.notify_all();
215 return _full_collections_completed;
216 }
217
218 // Update the _full_collections_completed counter, as appropriate,
219 // at the end of a concurrent GC cycle. Note the conditional update
220 // below to allow this method to be called by a concurrent collector
221 // without synchronizing in any manner with the VM thread (which
222 // may already have initiated a STW full collection "concurrently").
223 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
224 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
225 assert((_full_collections_completed <= _total_full_collections) &&
226 (count <= _total_full_collections),
227 "Can't complete more collections than were started");
228 if (count > _full_collections_completed) {
229 _full_collections_completed = count;
230 ml.notify_all();
231 }
232 return _full_collections_completed;
233 }
234
235
236 #ifndef PRODUCT
237 // Override of memory state checking method in CollectedHeap:
238 // Some collectors (CMS for example) can't have badHeapWordVal written
239 // in the first two words of an object. (For instance , in the case of
240 // CMS these words hold state used to synchronize between certain
241 // (concurrent) GC steps and direct allocating mutators.)
242 // The skip_header_HeapWords() method below, allows us to skip
243 // over the requisite number of HeapWord's. Note that (for
244 // generational collectors) this means that those many words are
245 // skipped in each object, irrespective of the generation in which
246 // that object lives. The resultant loss of precision seems to be
247 // harmless and the pain of avoiding that imprecision appears somewhat
248 // higher than we are prepared to pay for such rudimentary debugging
249 // support.
250 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
251 size_t size) {
252 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
253 // We are asked to check a size in HeapWords,
254 // but the memory is mangled in juint words.
255 juint* start = (juint*) (addr + skip_header_HeapWords());
256 juint* end = (juint*) (addr + size);
257 for (juint* slot = start; slot < end; slot += 1) {
258 assert(*slot == badHeapWordVal,
259 "Found non badHeapWordValue in pre-allocation check");
260 }
261 }
262 }
263 #endif
264
265 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
266 bool is_tlab,
267 bool first_only) {
268 HeapWord* res = NULL;
269
270 if (_young_gen->should_allocate(size, is_tlab)) {
271 res = _young_gen->allocate(size, is_tlab);
272 if (res != NULL || first_only) {
273 return res;
274 }
275 }
276
277 if (_old_gen->should_allocate(size, is_tlab)) {
278 res = _old_gen->allocate(size, is_tlab);
279 }
280
281 return res;
282 }
283
284 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
285 bool* gc_overhead_limit_was_exceeded) {
286 return gen_policy()->mem_allocate_work(size,
287 false /* is_tlab */,
288 gc_overhead_limit_was_exceeded);
289 }
290
291 bool GenCollectedHeap::must_clear_all_soft_refs() {
292 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
293 _gc_cause == GCCause::_wb_full_gc;
294 }
295
296 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
297 bool is_tlab, bool run_verification, bool clear_soft_refs,
298 bool restore_marks_for_biased_locking) {
299 FormatBuffer<> title("Collect gen: %s", gen->short_name());
300 GCTraceTime(Trace, gc, phases) t1(title);
301 TraceCollectorStats tcs(gen->counters());
302 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
303
304 gen->stat_record()->invocations++;
305 gen->stat_record()->accumulated_time.start();
306
307 // Must be done anew before each collection because
308 // a previous collection will do mangling and will
309 // change top of some spaces.
310 record_gen_tops_before_GC();
311
312 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
313
314 if (run_verification && VerifyBeforeGC) {
315 HandleMark hm; // Discard invalid handles created during verification
316 Universe::verify("Before GC");
317 }
318 COMPILER2_PRESENT(DerivedPointerTable::clear());
319
320 if (restore_marks_for_biased_locking) {
321 // We perform this mark word preservation work lazily
322 // because it's only at this point that we know whether we
323 // absolutely have to do it; we want to avoid doing it for
324 // scavenge-only collections where it's unnecessary
325 BiasedLocking::preserve_marks();
326 }
327
328 // Do collection work
329 {
330 // Note on ref discovery: For what appear to be historical reasons,
331 // GCH enables and disabled (by enqueing) refs discovery.
332 // In the future this should be moved into the generation's
333 // collect method so that ref discovery and enqueueing concerns
334 // are local to a generation. The collect method could return
335 // an appropriate indication in the case that notification on
336 // the ref lock was needed. This will make the treatment of
337 // weak refs more uniform (and indeed remove such concerns
338 // from GCH). XXX
339
340 HandleMark hm; // Discard invalid handles created during gc
341 save_marks(); // save marks for all gens
342 // We want to discover references, but not process them yet.
343 // This mode is disabled in process_discovered_references if the
344 // generation does some collection work, or in
345 // enqueue_discovered_references if the generation returns
346 // without doing any work.
347 ReferenceProcessor* rp = gen->ref_processor();
348 // If the discovery of ("weak") refs in this generation is
349 // atomic wrt other collectors in this configuration, we
350 // are guaranteed to have empty discovered ref lists.
351 if (rp->discovery_is_atomic()) {
352 rp->enable_discovery();
353 rp->setup_policy(clear_soft_refs);
354 } else {
355 // collect() below will enable discovery as appropriate
356 }
357 gen->collect(full, clear_soft_refs, size, is_tlab);
358 if (!rp->enqueuing_is_done()) {
359 rp->enqueue_discovered_references();
360 } else {
361 rp->set_enqueuing_is_done(false);
362 }
363 rp->verify_no_references_recorded();
364 }
365
366 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
367
368 gen->stat_record()->accumulated_time.stop();
369
370 update_gc_stats(gen, full);
371
372 if (run_verification && VerifyAfterGC) {
373 HandleMark hm; // Discard invalid handles created during verification
374 Universe::verify("After GC");
375 }
376 }
377
378 void GenCollectedHeap::do_collection(bool full,
379 bool clear_all_soft_refs,
380 size_t size,
381 bool is_tlab,
382 GenerationType max_generation) {
383 ResourceMark rm;
384 DEBUG_ONLY(Thread* my_thread = Thread::current();)
385
386 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
387 assert(my_thread->is_VM_thread() ||
388 my_thread->is_ConcurrentGC_thread(),
389 "incorrect thread type capability");
390 assert(Heap_lock->is_locked(),
391 "the requesting thread should have the Heap_lock");
392 guarantee(!is_gc_active(), "collection is not reentrant");
393
394 if (GCLocker::check_active_before_gc()) {
395 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
396 }
397
398 GCIdMarkAndRestore gc_id_mark;
399
400 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
401 collector_policy()->should_clear_all_soft_refs();
402
403 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
404
405 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
406
407 print_heap_before_gc();
408
409 {
410 FlagSetting fl(_is_gc_active, true);
411
412 bool complete = full && (max_generation == OldGen);
413 bool old_collects_young = complete && !ScavengeBeforeFullGC;
414 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
415
416 FormatBuffer<> gc_string("%s", "Pause ");
417 if (do_young_collection) {
418 gc_string.append("Young");
419 } else {
420 gc_string.append("Full");
421 }
422
423 GCTraceCPUTime tcpu;
424 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
425
426 gc_prologue(complete);
427 increment_total_collections(complete);
428
429 size_t young_prev_used = _young_gen->used();
430 size_t old_prev_used = _old_gen->used();
431
432 bool run_verification = total_collections() >= VerifyGCStartAt;
433
434 bool prepared_for_verification = false;
435 bool collected_old = false;
436
437 if (do_young_collection) {
438 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
439 prepare_for_verify();
440 prepared_for_verification = true;
441 }
442
443 collect_generation(_young_gen,
444 full,
445 size,
446 is_tlab,
447 run_verification && VerifyGCLevel <= 0,
448 do_clear_all_soft_refs,
449 false);
450
451 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
452 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
453 // Allocation request was met by young GC.
454 size = 0;
455 }
456 }
457
458 bool must_restore_marks_for_biased_locking = false;
459
460 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
461 if (!complete) {
462 // The full_collections increment was missed above.
463 increment_total_full_collections();
464 }
465
466 if (!prepared_for_verification && run_verification &&
467 VerifyGCLevel <= 1 && VerifyBeforeGC) {
468 prepare_for_verify();
469 }
470
471 if (do_young_collection) {
472 // We did a young GC. Need a new GC id for the old GC.
473 GCIdMarkAndRestore gc_id_mark;
474 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
475 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
476 } else {
477 // No young GC done. Use the same GC id as was set up earlier in this method.
478 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
479 }
480
481 must_restore_marks_for_biased_locking = true;
482 collected_old = true;
483 }
484
485 // Update "complete" boolean wrt what actually transpired --
486 // for instance, a promotion failure could have led to
487 // a whole heap collection.
488 complete = complete || collected_old;
489
490 print_heap_change(young_prev_used, old_prev_used);
491 MetaspaceAux::print_metaspace_change(metadata_prev_used);
492
493 // Adjust generation sizes.
494 if (collected_old) {
495 _old_gen->compute_new_size();
496 }
497 _young_gen->compute_new_size();
498
499 if (complete) {
500 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
501 ClassLoaderDataGraph::purge();
502 MetaspaceAux::verify_metrics();
503 // Resize the metaspace capacity after full collections
504 MetaspaceGC::compute_new_size();
505 update_full_collections_completed();
506 }
507
508 // Track memory usage and detect low memory after GC finishes
509 MemoryService::track_memory_usage();
510
511 gc_epilogue(complete);
512
513 if (must_restore_marks_for_biased_locking) {
514 BiasedLocking::restore_marks();
515 }
516 }
517
518 print_heap_after_gc();
519
520 #ifdef TRACESPINNING
521 ParallelTaskTerminator::print_termination_counts();
522 #endif
523 }
524
525 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
526 return gen_policy()->satisfy_failed_allocation(size, is_tlab);
527 }
528
529 #ifdef ASSERT
530 class AssertNonScavengableClosure: public OopClosure {
531 public:
532 virtual void do_oop(oop* p) {
533 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
534 "Referent should not be scavengable."); }
535 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
536 };
537 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
538 #endif
539
540 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
541 ScanningOption so,
542 OopClosure* strong_roots,
543 OopClosure* weak_roots,
544 CLDClosure* strong_cld_closure,
545 CLDClosure* weak_cld_closure,
546 CodeBlobToOopClosure* code_roots) {
547 // General roots.
548 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
549 assert(code_roots != NULL, "code root closure should always be set");
550 // _n_termination for _process_strong_tasks should be set up stream
551 // in a method not running in a GC worker. Otherwise the GC worker
552 // could be trying to change the termination condition while the task
553 // is executing in another GC worker.
554
555 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
556 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
557 }
558
559 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
560 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
561
562 bool is_par = scope->n_threads() > 1;
563 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
564
565 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
566 Universe::oops_do(strong_roots);
567 }
568 // Global (strong) JNI handles
569 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
570 JNIHandles::oops_do(strong_roots);
571 }
572
573 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
574 ObjectSynchronizer::oops_do(strong_roots);
575 }
576 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
577 FlatProfiler::oops_do(strong_roots);
578 }
579 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
580 Management::oops_do(strong_roots);
581 }
582 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
583 JvmtiExport::oops_do(strong_roots);
584 }
585
586 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
587 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
588 }
589
590 // All threads execute the following. A specific chunk of buckets
591 // from the StringTable are the individual tasks.
592 if (weak_roots != NULL) {
593 if (is_par) {
594 StringTable::possibly_parallel_oops_do(weak_roots);
595 } else {
596 StringTable::oops_do(weak_roots);
597 }
598 }
599
600 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
601 if (so & SO_ScavengeCodeCache) {
602 assert(code_roots != NULL, "must supply closure for code cache");
603
604 // We only visit parts of the CodeCache when scavenging.
605 CodeCache::scavenge_root_nmethods_do(code_roots);
606 }
607 if (so & SO_AllCodeCache) {
608 assert(code_roots != NULL, "must supply closure for code cache");
609
610 // CMSCollector uses this to do intermediate-strength collections.
611 // We scan the entire code cache, since CodeCache::do_unloading is not called.
612 CodeCache::blobs_do(code_roots);
613 }
614 // Verify that the code cache contents are not subject to
615 // movement by a scavenging collection.
616 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
617 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
618 }
619 }
620
621 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
622 GenerationType type,
623 bool young_gen_as_roots,
624 ScanningOption so,
625 bool only_strong_roots,
626 OopsInGenClosure* not_older_gens,
627 OopsInGenClosure* older_gens,
628 CLDClosure* cld_closure) {
629 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots;
630
631 bool is_moving_collection = false;
632 if (type == YoungGen || is_adjust_phase) {
633 // young collections are always moving
634 is_moving_collection = true;
635 }
636
637 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
638 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
639 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
640
641 process_roots(scope, so,
642 not_older_gens, weak_roots,
643 cld_closure, weak_cld_closure,
644 &mark_code_closure);
645
646 if (young_gen_as_roots) {
647 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
648 if (type == OldGen) {
649 not_older_gens->set_generation(_young_gen);
650 _young_gen->oop_iterate(not_older_gens);
651 }
652 not_older_gens->reset_generation();
653 }
654 }
655 // When collection is parallel, all threads get to cooperate to do
656 // old generation scanning.
657 if (type == YoungGen) {
658 older_gens->set_generation(_old_gen);
659 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
660 older_gens->reset_generation();
661 }
662
663 _process_strong_tasks->all_tasks_completed(scope->n_threads());
664 }
665
666 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
667 JNIHandles::weak_oops_do(root_closure);
668 _young_gen->ref_processor()->weak_oops_do(root_closure);
669 _old_gen->ref_processor()->weak_oops_do(root_closure);
670 }
671
672 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
673 void GenCollectedHeap:: \
674 oop_since_save_marks_iterate(GenerationType gen, \
675 OopClosureType* cur, \
676 OopClosureType* older) { \
677 if (gen == YoungGen) { \
678 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
679 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
680 } else { \
681 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
682 } \
683 }
684
685 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
686
687 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
688
689 bool GenCollectedHeap::no_allocs_since_save_marks() {
690 return _young_gen->no_allocs_since_save_marks() &&
691 _old_gen->no_allocs_since_save_marks();
692 }
693
694 bool GenCollectedHeap::supports_inline_contig_alloc() const {
695 return _young_gen->supports_inline_contig_alloc();
696 }
697
698 HeapWord** GenCollectedHeap::top_addr() const {
699 return _young_gen->top_addr();
700 }
701
702 HeapWord** GenCollectedHeap::end_addr() const {
703 return _young_gen->end_addr();
704 }
705
706 // public collection interfaces
707
708 void GenCollectedHeap::collect(GCCause::Cause cause) {
709 if (cause == GCCause::_wb_young_gc) {
710 // Young collection for the WhiteBox API.
711 collect(cause, YoungGen);
712 } else {
713 #ifdef ASSERT
714 if (cause == GCCause::_scavenge_alot) {
715 // Young collection only.
716 collect(cause, YoungGen);
717 } else {
718 // Stop-the-world full collection.
719 collect(cause, OldGen);
720 }
721 #else
722 // Stop-the-world full collection.
723 collect(cause, OldGen);
724 #endif
725 }
726 }
727
728 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
729 // The caller doesn't have the Heap_lock
730 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
731 MutexLocker ml(Heap_lock);
732 collect_locked(cause, max_generation);
733 }
734
735 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
736 // The caller has the Heap_lock
737 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
738 collect_locked(cause, OldGen);
739 }
740
741 // this is the private collection interface
742 // The Heap_lock is expected to be held on entry.
743
744 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
745 // Read the GC count while holding the Heap_lock
746 unsigned int gc_count_before = total_collections();
747 unsigned int full_gc_count_before = total_full_collections();
748 {
749 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
750 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
751 cause, max_generation);
752 VMThread::execute(&op);
753 }
754 }
755
756 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
757 do_full_collection(clear_all_soft_refs, OldGen);
758 }
759
760 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
761 GenerationType last_generation) {
762 GenerationType local_last_generation;
763 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
764 gc_cause() == GCCause::_gc_locker) {
765 local_last_generation = YoungGen;
766 } else {
767 local_last_generation = last_generation;
768 }
769
770 do_collection(true, // full
771 clear_all_soft_refs, // clear_all_soft_refs
772 0, // size
773 false, // is_tlab
774 local_last_generation); // last_generation
775 // Hack XXX FIX ME !!!
776 // A scavenge may not have been attempted, or may have
777 // been attempted and failed, because the old gen was too full
778 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
779 incremental_collection_will_fail(false /* don't consult_young */)) {
780 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
781 // This time allow the old gen to be collected as well
782 do_collection(true, // full
783 clear_all_soft_refs, // clear_all_soft_refs
784 0, // size
785 false, // is_tlab
786 OldGen); // last_generation
787 }
788 }
789
790 bool GenCollectedHeap::is_in_young(oop p) {
791 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
792 assert(result == _young_gen->is_in_reserved(p),
793 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
794 return result;
795 }
796
797 // Returns "TRUE" iff "p" points into the committed areas of the heap.
798 bool GenCollectedHeap::is_in(const void* p) const {
799 return _young_gen->is_in(p) || _old_gen->is_in(p);
800 }
801
802 #ifdef ASSERT
803 // Don't implement this by using is_in_young(). This method is used
804 // in some cases to check that is_in_young() is correct.
805 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
806 assert(is_in_reserved(p) || p == NULL,
807 "Does not work if address is non-null and outside of the heap");
808 return p < _young_gen->reserved().end() && p != NULL;
809 }
810 #endif
811
812 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
813 NoHeaderExtendedOopClosure no_header_cl(cl);
814 oop_iterate(&no_header_cl);
815 }
816
817 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
818 _young_gen->oop_iterate(cl);
819 _old_gen->oop_iterate(cl);
820 }
821
822 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
823 _young_gen->object_iterate(cl);
824 _old_gen->object_iterate(cl);
825 }
826
827 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
828 _young_gen->safe_object_iterate(cl);
829 _old_gen->safe_object_iterate(cl);
830 }
831
832 Space* GenCollectedHeap::space_containing(const void* addr) const {
833 Space* res = _young_gen->space_containing(addr);
834 if (res != NULL) {
835 return res;
836 }
837 res = _old_gen->space_containing(addr);
838 assert(res != NULL, "Could not find containing space");
839 return res;
840 }
841
842 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
843 assert(is_in_reserved(addr), "block_start of address outside of heap");
844 if (_young_gen->is_in_reserved(addr)) {
845 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
846 return _young_gen->block_start(addr);
847 }
848
849 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
850 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
851 return _old_gen->block_start(addr);
852 }
853
854 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
855 assert(is_in_reserved(addr), "block_size of address outside of heap");
856 if (_young_gen->is_in_reserved(addr)) {
857 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
858 return _young_gen->block_size(addr);
859 }
860
861 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
862 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
863 return _old_gen->block_size(addr);
864 }
865
866 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
867 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
868 assert(block_start(addr) == addr, "addr must be a block start");
869 if (_young_gen->is_in_reserved(addr)) {
870 return _young_gen->block_is_obj(addr);
871 }
872
873 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
874 return _old_gen->block_is_obj(addr);
875 }
876
877 bool GenCollectedHeap::supports_tlab_allocation() const {
878 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
879 return _young_gen->supports_tlab_allocation();
880 }
881
882 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
883 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
884 if (_young_gen->supports_tlab_allocation()) {
885 return _young_gen->tlab_capacity();
886 }
887 return 0;
888 }
889
890 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
891 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
892 if (_young_gen->supports_tlab_allocation()) {
893 return _young_gen->tlab_used();
894 }
895 return 0;
896 }
897
898 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
899 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
900 if (_young_gen->supports_tlab_allocation()) {
901 return _young_gen->unsafe_max_tlab_alloc();
902 }
903 return 0;
904 }
905
906 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
907 bool gc_overhead_limit_was_exceeded;
908 return gen_policy()->mem_allocate_work(size /* size */,
909 true /* is_tlab */,
910 &gc_overhead_limit_was_exceeded);
911 }
912
913 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
914 // from the list headed by "*prev_ptr".
915 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
916 bool first = true;
917 size_t min_size = 0; // "first" makes this conceptually infinite.
918 ScratchBlock **smallest_ptr, *smallest;
919 ScratchBlock *cur = *prev_ptr;
920 while (cur) {
921 assert(*prev_ptr == cur, "just checking");
922 if (first || cur->num_words < min_size) {
923 smallest_ptr = prev_ptr;
924 smallest = cur;
925 min_size = smallest->num_words;
926 first = false;
927 }
928 prev_ptr = &cur->next;
929 cur = cur->next;
930 }
931 smallest = *smallest_ptr;
932 *smallest_ptr = smallest->next;
933 return smallest;
934 }
935
936 // Sort the scratch block list headed by res into decreasing size order,
937 // and set "res" to the result.
938 static void sort_scratch_list(ScratchBlock*& list) {
939 ScratchBlock* sorted = NULL;
940 ScratchBlock* unsorted = list;
941 while (unsorted) {
942 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
943 smallest->next = sorted;
944 sorted = smallest;
945 }
946 list = sorted;
947 }
948
949 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
950 size_t max_alloc_words) {
951 ScratchBlock* res = NULL;
952 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
953 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
954 sort_scratch_list(res);
955 return res;
956 }
957
958 void GenCollectedHeap::release_scratch() {
959 _young_gen->reset_scratch();
960 _old_gen->reset_scratch();
961 }
962
963 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
964 void do_generation(Generation* gen) {
965 gen->prepare_for_verify();
966 }
967 };
968
969 void GenCollectedHeap::prepare_for_verify() {
970 ensure_parsability(false); // no need to retire TLABs
971 GenPrepareForVerifyClosure blk;
972 generation_iterate(&blk, false);
973 }
974
975 void GenCollectedHeap::generation_iterate(GenClosure* cl,
976 bool old_to_young) {
977 if (old_to_young) {
978 cl->do_generation(_old_gen);
979 cl->do_generation(_young_gen);
980 } else {
981 cl->do_generation(_young_gen);
982 cl->do_generation(_old_gen);
983 }
984 }
985
986 bool GenCollectedHeap::is_maximal_no_gc() const {
987 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
988 }
989
990 void GenCollectedHeap::save_marks() {
991 _young_gen->save_marks();
992 _old_gen->save_marks();
993 }
994
995 GenCollectedHeap* GenCollectedHeap::heap() {
996 CollectedHeap* heap = GC::gc()->heap();
997 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
998 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
999 return (GenCollectedHeap*)heap;
1000 }
1001
1002 void GenCollectedHeap::prepare_for_compaction() {
1003 // Start by compacting into same gen.
1004 CompactPoint cp(_old_gen);
1005 _old_gen->prepare_for_compaction(&cp);
1006 _young_gen->prepare_for_compaction(&cp);
1007 }
1008
1009 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1010 log_debug(gc, verify)("%s", _old_gen->name());
1011 _old_gen->verify();
1012
1013 log_debug(gc, verify)("%s", _old_gen->name());
1014 _young_gen->verify();
1015
1016 log_debug(gc, verify)("RemSet");
1017 rem_set()->verify();
1018 }
1019
1020 void GenCollectedHeap::print_on(outputStream* st) const {
1021 _young_gen->print_on(st);
1022 _old_gen->print_on(st);
1023 MetaspaceAux::print_on(st);
1024 }
1025
1026 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1027 if (workers() != NULL) {
1028 workers()->threads_do(tc);
1029 }
1030 }
1031
1032 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1033 }
1034
1035 void GenCollectedHeap::print_on_error(outputStream* st) const {
1036 this->CollectedHeap::print_on_error(st);
1037 }
1038
1039 void GenCollectedHeap::print_tracing_info() const {
1040 if (TraceYoungGenTime) {
1041 _young_gen->print_summary_info();
1042 }
1043 if (TraceOldGenTime) {
1044 _old_gen->print_summary_info();
1045 }
1046 }
1047
1048 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1049 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1050 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1051 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1052 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1053 }
1054
1055 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1056 private:
1057 bool _full;
1058 public:
1059 void do_generation(Generation* gen) {
1060 gen->gc_prologue(_full);
1061 }
1062 GenGCPrologueClosure(bool full) : _full(full) {};
1063 };
1064
1065 void GenCollectedHeap::gc_prologue(bool full) {
1066 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1067
1068 always_do_update_barrier = false;
1069 // Fill TLAB's and such
1070 CollectedHeap::accumulate_statistics_all_tlabs();
1071 ensure_parsability(true); // retire TLABs
1072
1073 // Walk generations
1074 GenGCPrologueClosure blk(full);
1075 generation_iterate(&blk, false); // not old-to-young.
1076 };
1077
1078 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1079 private:
1080 bool _full;
1081 public:
1082 void do_generation(Generation* gen) {
1083 gen->gc_epilogue(_full);
1084 }
1085 GenGCEpilogueClosure(bool full) : _full(full) {};
1086 };
1087
1088 void GenCollectedHeap::gc_epilogue(bool full) {
1089 #if defined(COMPILER2) || INCLUDE_JVMCI
1090 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1091 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1092 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1093 #endif /* COMPILER2 || INCLUDE_JVMCI */
1094
1095 resize_all_tlabs();
1096
1097 GenGCEpilogueClosure blk(full);
1098 generation_iterate(&blk, false); // not old-to-young.
1099
1100 if (!CleanChunkPoolAsync) {
1101 Chunk::clean_chunk_pool();
1102 }
1103
1104 MetaspaceCounters::update_performance_counters();
1105 CompressedClassSpaceCounters::update_performance_counters();
1106
1107 always_do_update_barrier = UseConcMarkSweepGC;
1108 };
1109
1110 #ifndef PRODUCT
1111 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1112 private:
1113 public:
1114 void do_generation(Generation* gen) {
1115 gen->record_spaces_top();
1116 }
1117 };
1118
1119 void GenCollectedHeap::record_gen_tops_before_GC() {
1120 if (ZapUnusedHeapArea) {
1121 GenGCSaveTopsBeforeGCClosure blk;
1122 generation_iterate(&blk, false); // not old-to-young.
1123 }
1124 }
1125 #endif // not PRODUCT
1126
1127 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1128 public:
1129 void do_generation(Generation* gen) {
1130 gen->ensure_parsability();
1131 }
1132 };
1133
1134 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1135 CollectedHeap::ensure_parsability(retire_tlabs);
1136 GenEnsureParsabilityClosure ep_cl;
1137 generation_iterate(&ep_cl, false);
1138 }
1139
1140 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1141 oop obj,
1142 size_t obj_size) {
1143 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1144 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1145 HeapWord* result = NULL;
1146
1147 result = old_gen->expand_and_allocate(obj_size, false);
1148
1149 if (result != NULL) {
1150 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1151 }
1152 return oop(result);
1153 }
1154
1155 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1156 jlong _time; // in ms
1157 jlong _now; // in ms
1158
1159 public:
1160 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1161
1162 jlong time() { return _time; }
1163
1164 void do_generation(Generation* gen) {
1165 _time = MIN2(_time, gen->time_of_last_gc(_now));
1166 }
1167 };
1168
1169 jlong GenCollectedHeap::millis_since_last_gc() {
1170 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1171 // provided the underlying platform provides such a time source
1172 // (and it is bug free). So we still have to guard against getting
1173 // back a time later than 'now'.
1174 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1175 GenTimeOfLastGCClosure tolgc_cl(now);
1176 // iterate over generations getting the oldest
1177 // time that a generation was collected
1178 generation_iterate(&tolgc_cl, false);
1179
1180 jlong retVal = now - tolgc_cl.time();
1181 if (retVal < 0) {
1182 log_warning(gc)("Detected clock going backwards. "
1183 "Milliseconds since last GC would be " JLONG_FORMAT
1184 ". returning zero instead.", retVal);
1185 return 0;
1186 }
1187 return retVal;
1188 }