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