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/stringTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/icBuffer.hpp"
33 #include "gc/shared/collectedHeap.inline.hpp"
34 #include "gc/shared/collectorCounters.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/gcTrace.hpp"
38 #include "gc/shared/gcTraceTime.inline.hpp"
39 #include "gc/shared/genCollectedHeap.hpp"
40 #include "gc/shared/genOopClosures.inline.hpp"
41 #include "gc/shared/generationSpec.hpp"
42 #include "gc/shared/space.hpp"
43 #include "gc/shared/strongRootsScope.hpp"
44 #include "gc/shared/vmGCOperations.hpp"
45 #include "gc/shared/weakProcessor.hpp"
46 #include "gc/shared/workgroup.hpp"
47 #include "memory/filemap.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "runtime/biasedLocking.hpp"
51 #include "runtime/handles.hpp"
52 #include "runtime/handles.inline.hpp"
53 #include "runtime/java.hpp"
54 #include "runtime/vmThread.hpp"
55 #include "services/management.hpp"
56 #include "services/memoryService.hpp"
57 #include "utilities/debug.hpp"
58 #include "utilities/formatBuffer.hpp"
59 #include "utilities/macros.hpp"
60 #include "utilities/stack.inline.hpp"
61 #include "utilities/vmError.hpp"
62
63 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
64 CollectedHeap(),
65 _rem_set(NULL),
66 _gen_policy(policy),
67 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
68 _full_collections_completed(0)
69 {
70 assert(policy != NULL, "Sanity check");
71 }
72
73 jint GenCollectedHeap::initialize() {
74 CollectedHeap::pre_initialize();
75
76 // While there are no constraints in the GC code that HeapWordSize
77 // be any particular value, there are multiple other areas in the
78 // system which believe this to be true (e.g. oop->object_size in some
79 // cases incorrectly returns the size in wordSize units rather than
80 // HeapWordSize).
81 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
82
83 // Allocate space for the heap.
84
85 char* heap_address;
86 ReservedSpace heap_rs;
87
88 size_t heap_alignment = collector_policy()->heap_alignment();
89
90 heap_address = allocate(heap_alignment, &heap_rs);
91
92 if (!heap_rs.is_reserved()) {
93 vm_shutdown_during_initialization(
94 "Could not reserve enough space for object heap");
95 return JNI_ENOMEM;
96 }
97
98 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
99
100 _rem_set = collector_policy()->create_rem_set(reserved_region());
101 set_barrier_set(rem_set()->bs());
102
103 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
104 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
105 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
106
107 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
108 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
109 clear_incremental_collection_failed();
110
111 return JNI_OK;
112 }
113
114 char* GenCollectedHeap::allocate(size_t alignment,
115 ReservedSpace* heap_rs){
116 // Now figure out the total size.
117 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
118 assert(alignment % pageSize == 0, "Must be");
119
120 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
121 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
122
123 // Check for overflow.
124 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
125 if (total_reserved < young_spec->max_size()) {
126 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
127 "the maximum representable size");
128 }
129 assert(total_reserved % alignment == 0,
130 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
131 SIZE_FORMAT, total_reserved, alignment);
132
133 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
134
135 os::trace_page_sizes("Heap",
136 collector_policy()->min_heap_byte_size(),
137 total_reserved,
138 alignment,
139 heap_rs->base(),
140 heap_rs->size());
141
142 return heap_rs->base();
143 }
144
145 void GenCollectedHeap::post_initialize() {
146 ref_processing_init();
147 check_gen_kinds();
148 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
149
150 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
151 _old_gen->capacity(),
152 def_new_gen->from()->capacity());
153 _gen_policy->initialize_gc_policy_counters();
154 }
155
156 void GenCollectedHeap::check_gen_kinds() {
157 assert(young_gen()->kind() == Generation::DefNew,
158 "Wrong youngest generation type");
159 assert(old_gen()->kind() == Generation::MarkSweepCompact,
160 "Wrong generation kind");
161 }
162
163 void GenCollectedHeap::ref_processing_init() {
164 _young_gen->ref_processor_init();
165 _old_gen->ref_processor_init();
166 }
167
168 size_t GenCollectedHeap::capacity() const {
169 return _young_gen->capacity() + _old_gen->capacity();
170 }
171
172 size_t GenCollectedHeap::used() const {
173 return _young_gen->used() + _old_gen->used();
174 }
175
176 void GenCollectedHeap::save_used_regions() {
177 _old_gen->save_used_region();
178 _young_gen->save_used_region();
179 }
180
181 size_t GenCollectedHeap::max_capacity() const {
182 return _young_gen->max_capacity() + _old_gen->max_capacity();
183 }
184
185 // Update the _full_collections_completed counter
186 // at the end of a stop-world full GC.
187 unsigned int GenCollectedHeap::update_full_collections_completed() {
188 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
189 assert(_full_collections_completed <= _total_full_collections,
190 "Can't complete more collections than were started");
191 _full_collections_completed = _total_full_collections;
192 ml.notify_all();
193 return _full_collections_completed;
194 }
195
196 // Update the _full_collections_completed counter, as appropriate,
197 // at the end of a concurrent GC cycle. Note the conditional update
198 // below to allow this method to be called by a concurrent collector
199 // without synchronizing in any manner with the VM thread (which
200 // may already have initiated a STW full collection "concurrently").
201 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
202 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
203 assert((_full_collections_completed <= _total_full_collections) &&
204 (count <= _total_full_collections),
205 "Can't complete more collections than were started");
206 if (count > _full_collections_completed) {
207 _full_collections_completed = count;
208 ml.notify_all();
209 }
210 return _full_collections_completed;
211 }
212
213
214 #ifndef PRODUCT
215 // Override of memory state checking method in CollectedHeap:
216 // Some collectors (CMS for example) can't have badHeapWordVal written
217 // in the first two words of an object. (For instance , in the case of
218 // CMS these words hold state used to synchronize between certain
219 // (concurrent) GC steps and direct allocating mutators.)
220 // The skip_header_HeapWords() method below, allows us to skip
221 // over the requisite number of HeapWord's. Note that (for
222 // generational collectors) this means that those many words are
223 // skipped in each object, irrespective of the generation in which
224 // that object lives. The resultant loss of precision seems to be
225 // harmless and the pain of avoiding that imprecision appears somewhat
226 // higher than we are prepared to pay for such rudimentary debugging
227 // support.
228 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
229 size_t size) {
230 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
231 // We are asked to check a size in HeapWords,
232 // but the memory is mangled in juint words.
233 juint* start = (juint*) (addr + skip_header_HeapWords());
234 juint* end = (juint*) (addr + size);
235 for (juint* slot = start; slot < end; slot += 1) {
236 assert(*slot == badHeapWordVal,
237 "Found non badHeapWordValue in pre-allocation check");
238 }
239 }
240 }
241 #endif
242
243 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
244 bool is_tlab,
245 bool first_only) {
246 HeapWord* res = NULL;
247
248 if (_young_gen->should_allocate(size, is_tlab)) {
249 res = _young_gen->allocate(size, is_tlab);
250 if (res != NULL || first_only) {
251 return res;
252 }
253 }
254
255 if (_old_gen->should_allocate(size, is_tlab)) {
256 res = _old_gen->allocate(size, is_tlab);
257 }
258
259 return res;
260 }
261
262 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
263 bool* gc_overhead_limit_was_exceeded) {
264 return gen_policy()->mem_allocate_work(size,
265 false /* is_tlab */,
266 gc_overhead_limit_was_exceeded);
267 }
268
269 bool GenCollectedHeap::must_clear_all_soft_refs() {
270 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
271 _gc_cause == GCCause::_wb_full_gc;
272 }
273
274 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
275 bool is_tlab, bool run_verification, bool clear_soft_refs,
276 bool restore_marks_for_biased_locking) {
277 FormatBuffer<> title("Collect gen: %s", gen->short_name());
278 GCTraceTime(Trace, gc, phases) t1(title);
279 TraceCollectorStats tcs(gen->counters());
280 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
281
282 gen->stat_record()->invocations++;
283 gen->stat_record()->accumulated_time.start();
284
285 // Must be done anew before each collection because
286 // a previous collection will do mangling and will
287 // change top of some spaces.
288 record_gen_tops_before_GC();
289
290 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
291
292 if (run_verification && VerifyBeforeGC) {
293 HandleMark hm; // Discard invalid handles created during verification
294 Universe::verify("Before GC");
295 }
296 COMPILER2_PRESENT(DerivedPointerTable::clear());
297
298 if (restore_marks_for_biased_locking) {
299 // We perform this mark word preservation work lazily
300 // because it's only at this point that we know whether we
301 // absolutely have to do it; we want to avoid doing it for
302 // scavenge-only collections where it's unnecessary
303 BiasedLocking::preserve_marks();
304 }
305
306 // Do collection work
307 {
308 // Note on ref discovery: For what appear to be historical reasons,
309 // GCH enables and disabled (by enqueing) refs discovery.
310 // In the future this should be moved into the generation's
311 // collect method so that ref discovery and enqueueing concerns
312 // are local to a generation. The collect method could return
313 // an appropriate indication in the case that notification on
314 // the ref lock was needed. This will make the treatment of
315 // weak refs more uniform (and indeed remove such concerns
316 // from GCH). XXX
317
318 HandleMark hm; // Discard invalid handles created during gc
319 save_marks(); // save marks for all gens
320 // We want to discover references, but not process them yet.
321 // This mode is disabled in process_discovered_references if the
322 // generation does some collection work, or in
323 // enqueue_discovered_references if the generation returns
324 // without doing any work.
325 ReferenceProcessor* rp = gen->ref_processor();
326 // If the discovery of ("weak") refs in this generation is
327 // atomic wrt other collectors in this configuration, we
328 // are guaranteed to have empty discovered ref lists.
329 if (rp->discovery_is_atomic()) {
330 rp->enable_discovery();
331 rp->setup_policy(clear_soft_refs);
332 } else {
333 // collect() below will enable discovery as appropriate
334 }
335 gen->collect(full, clear_soft_refs, size, is_tlab);
336 if (!rp->enqueuing_is_done()) {
337 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q());
338 rp->enqueue_discovered_references(NULL, &pt);
339 pt.print_enqueue_phase();
340 } else {
341 rp->set_enqueuing_is_done(false);
342 }
343 rp->verify_no_references_recorded();
344 }
345
346 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
347
348 gen->stat_record()->accumulated_time.stop();
349
350 update_gc_stats(gen, full);
351
352 if (run_verification && VerifyAfterGC) {
353 HandleMark hm; // Discard invalid handles created during verification
354 Universe::verify("After GC");
355 }
356 }
357
358 void GenCollectedHeap::do_collection(bool full,
359 bool clear_all_soft_refs,
360 size_t size,
361 bool is_tlab,
362 GenerationType max_generation) {
363 ResourceMark rm;
364 DEBUG_ONLY(Thread* my_thread = Thread::current();)
365
366 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
367 assert(my_thread->is_VM_thread() ||
368 my_thread->is_ConcurrentGC_thread(),
369 "incorrect thread type capability");
370 assert(Heap_lock->is_locked(),
371 "the requesting thread should have the Heap_lock");
372 guarantee(!is_gc_active(), "collection is not reentrant");
373
374 if (GCLocker::check_active_before_gc()) {
375 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
376 }
377
378 GCIdMarkAndRestore gc_id_mark;
379
380 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
381 collector_policy()->should_clear_all_soft_refs();
382
383 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
384
385 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
386
387 print_heap_before_gc();
388
389 {
390 FlagSetting fl(_is_gc_active, true);
391
392 bool complete = full && (max_generation == OldGen);
393 bool old_collects_young = complete && !ScavengeBeforeFullGC;
394 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
395
396 FormatBuffer<> gc_string("%s", "Pause ");
397 if (do_young_collection) {
398 gc_string.append("Young");
399 } else {
400 gc_string.append("Full");
401 }
402
403 GCTraceCPUTime tcpu;
404 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
405
406 gc_prologue(complete);
407 increment_total_collections(complete);
408
409 size_t young_prev_used = _young_gen->used();
410 size_t old_prev_used = _old_gen->used();
411
412 bool run_verification = total_collections() >= VerifyGCStartAt;
413
414 bool prepared_for_verification = false;
415 bool collected_old = false;
416
417 if (do_young_collection) {
418 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
419 prepare_for_verify();
420 prepared_for_verification = true;
421 }
422
423 collect_generation(_young_gen,
424 full,
425 size,
426 is_tlab,
427 run_verification && VerifyGCLevel <= 0,
428 do_clear_all_soft_refs,
429 false);
430
431 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
432 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
433 // Allocation request was met by young GC.
434 size = 0;
435 }
436 }
437
438 bool must_restore_marks_for_biased_locking = false;
439
440 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
441 if (!complete) {
442 // The full_collections increment was missed above.
443 increment_total_full_collections();
444 }
445
446 if (!prepared_for_verification && run_verification &&
447 VerifyGCLevel <= 1 && VerifyBeforeGC) {
448 prepare_for_verify();
449 }
450
451 if (do_young_collection) {
452 // We did a young GC. Need a new GC id for the old GC.
453 GCIdMarkAndRestore gc_id_mark;
454 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
455 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
456 } else {
457 // No young GC done. Use the same GC id as was set up earlier in this method.
458 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
459 }
460
461 must_restore_marks_for_biased_locking = true;
462 collected_old = true;
463 }
464
465 // Update "complete" boolean wrt what actually transpired --
466 // for instance, a promotion failure could have led to
467 // a whole heap collection.
468 complete = complete || collected_old;
469
470 print_heap_change(young_prev_used, old_prev_used);
471 MetaspaceAux::print_metaspace_change(metadata_prev_used);
472
473 // Adjust generation sizes.
474 if (collected_old) {
475 _old_gen->compute_new_size();
476 }
477 _young_gen->compute_new_size();
478
479 if (complete) {
480 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
481 ClassLoaderDataGraph::purge();
482 MetaspaceAux::verify_metrics();
483 // Resize the metaspace capacity after full collections
484 MetaspaceGC::compute_new_size();
485 update_full_collections_completed();
486 }
487
488 // Track memory usage and detect low memory after GC finishes
489 MemoryService::track_memory_usage();
490
491 gc_epilogue(complete);
492
493 if (must_restore_marks_for_biased_locking) {
494 BiasedLocking::restore_marks();
495 }
496 }
497
498 print_heap_after_gc();
499
500 #ifdef TRACESPINNING
501 ParallelTaskTerminator::print_termination_counts();
502 #endif
503 }
504
505 void GenCollectedHeap::register_nmethod(nmethod* nm) {
506 CodeCache::register_scavenge_root_nmethod(nm);
507 }
508
509 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
510 CodeCache::verify_scavenge_root_nmethod(nm);
511 }
512
513 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
514 return gen_policy()->satisfy_failed_allocation(size, is_tlab);
515 }
516
517 #ifdef ASSERT
518 class AssertNonScavengableClosure: public OopClosure {
519 public:
520 virtual void do_oop(oop* p) {
521 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
522 "Referent should not be scavengable."); }
523 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
524 };
525 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
526 #endif
527
528 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
529 ScanningOption so,
530 OopClosure* strong_roots,
531 OopClosure* weak_roots,
532 CLDClosure* strong_cld_closure,
533 CLDClosure* weak_cld_closure,
534 CodeBlobToOopClosure* code_roots) {
535 // General roots.
536 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
537 assert(code_roots != NULL, "code root closure should always be set");
538 // _n_termination for _process_strong_tasks should be set up stream
539 // in a method not running in a GC worker. Otherwise the GC worker
540 // could be trying to change the termination condition while the task
541 // is executing in another GC worker.
542
543 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
544 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
545 }
546
547 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
548 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
549
550 bool is_par = scope->n_threads() > 1;
551 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
552
553 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
554 Universe::oops_do(strong_roots);
555 }
556 // Global (strong) JNI handles
557 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
558 JNIHandles::oops_do(strong_roots);
559 }
560
561 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
562 ObjectSynchronizer::oops_do(strong_roots);
563 }
564 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
565 Management::oops_do(strong_roots);
566 }
567 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
568 JvmtiExport::oops_do(strong_roots);
569 }
570 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
571 AOTLoader::oops_do(strong_roots);
572 }
573
574 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
575 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
576 }
577
578 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
579 if (so & SO_ScavengeCodeCache) {
580 assert(code_roots != NULL, "must supply closure for code cache");
581
582 // We only visit parts of the CodeCache when scavenging.
583 CodeCache::scavenge_root_nmethods_do(code_roots);
584 }
585 if (so & SO_AllCodeCache) {
586 assert(code_roots != NULL, "must supply closure for code cache");
587
588 // CMSCollector uses this to do intermediate-strength collections.
589 // We scan the entire code cache, since CodeCache::do_unloading is not called.
590 CodeCache::blobs_do(code_roots);
591 }
592 // Verify that the code cache contents are not subject to
593 // movement by a scavenging collection.
594 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
595 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
596 }
597 }
598
599 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
600 OopClosure* root_closure) {
601 assert(root_closure != NULL, "Must be set");
602 // All threads execute the following. A specific chunk of buckets
603 // from the StringTable are the individual tasks.
604 if (scope->n_threads() > 1) {
605 StringTable::possibly_parallel_oops_do(root_closure);
606 } else {
607 StringTable::oops_do(root_closure);
608 }
609 }
610
611 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
612 OopsInGenClosure* root_closure,
613 OopsInGenClosure* old_gen_closure,
614 CLDClosure* cld_closure) {
615 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
616
617 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
618 cld_closure, cld_closure, &mark_code_closure);
619 process_string_table_roots(scope, root_closure);
620
621 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
622 root_closure->reset_generation();
623 }
624
625 // When collection is parallel, all threads get to cooperate to do
626 // old generation scanning.
627 old_gen_closure->set_generation(_old_gen);
628 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
629 old_gen_closure->reset_generation();
630
631 _process_strong_tasks->all_tasks_completed(scope->n_threads());
632 }
633
634 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
635 bool is_adjust_phase,
636 ScanningOption so,
637 bool only_strong_roots,
638 OopsInGenClosure* root_closure,
639 CLDClosure* cld_closure) {
640 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
641 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
642 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
643
644 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
645 if (is_adjust_phase) {
646 // We never treat the string table as roots during marking
647 // for the full gc, so we only need to process it during
648 // the adjust phase.
649 process_string_table_roots(scope, root_closure);
650 }
651
652 _process_strong_tasks->all_tasks_completed(scope->n_threads());
653 }
654
655 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
656 WeakProcessor::oops_do(root_closure);
657 _young_gen->ref_processor()->weak_oops_do(root_closure);
658 _old_gen->ref_processor()->weak_oops_do(root_closure);
659 }
660
661 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
662 void GenCollectedHeap:: \
663 oop_since_save_marks_iterate(GenerationType gen, \
664 OopClosureType* cur, \
665 OopClosureType* older) { \
666 if (gen == YoungGen) { \
667 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
668 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
669 } else { \
670 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
671 } \
672 }
673
674 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
675
676 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
677
678 bool GenCollectedHeap::no_allocs_since_save_marks() {
679 return _young_gen->no_allocs_since_save_marks() &&
680 _old_gen->no_allocs_since_save_marks();
681 }
682
683 bool GenCollectedHeap::supports_inline_contig_alloc() const {
684 return _young_gen->supports_inline_contig_alloc();
685 }
686
687 HeapWord* volatile* GenCollectedHeap::top_addr() const {
688 return _young_gen->top_addr();
689 }
690
691 HeapWord** GenCollectedHeap::end_addr() const {
692 return _young_gen->end_addr();
693 }
694
695 // public collection interfaces
696
697 void GenCollectedHeap::collect(GCCause::Cause cause) {
698 if (cause == GCCause::_wb_young_gc) {
699 // Young collection for the WhiteBox API.
700 collect(cause, YoungGen);
701 } else {
702 #ifdef ASSERT
703 if (cause == GCCause::_scavenge_alot) {
704 // Young collection only.
705 collect(cause, YoungGen);
706 } else {
707 // Stop-the-world full collection.
708 collect(cause, OldGen);
709 }
710 #else
711 // Stop-the-world full collection.
712 collect(cause, OldGen);
713 #endif
714 }
715 }
716
717 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
718 // The caller doesn't have the Heap_lock
719 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
720 MutexLocker ml(Heap_lock);
721 collect_locked(cause, max_generation);
722 }
723
724 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
725 // The caller has the Heap_lock
726 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
727 collect_locked(cause, OldGen);
728 }
729
730 // this is the private collection interface
731 // The Heap_lock is expected to be held on entry.
732
733 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
734 // Read the GC count while holding the Heap_lock
735 unsigned int gc_count_before = total_collections();
736 unsigned int full_gc_count_before = total_full_collections();
737 {
738 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
739 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
740 cause, max_generation);
741 VMThread::execute(&op);
742 }
743 }
744
745 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
746 do_full_collection(clear_all_soft_refs, OldGen);
747 }
748
749 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
750 GenerationType last_generation) {
751 GenerationType local_last_generation;
752 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
753 gc_cause() == GCCause::_gc_locker) {
754 local_last_generation = YoungGen;
755 } else {
756 local_last_generation = last_generation;
757 }
758
759 do_collection(true, // full
760 clear_all_soft_refs, // clear_all_soft_refs
761 0, // size
762 false, // is_tlab
763 local_last_generation); // last_generation
764 // Hack XXX FIX ME !!!
765 // A scavenge may not have been attempted, or may have
766 // been attempted and failed, because the old gen was too full
767 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
768 incremental_collection_will_fail(false /* don't consult_young */)) {
769 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
770 // This time allow the old gen to be collected as well
771 do_collection(true, // full
772 clear_all_soft_refs, // clear_all_soft_refs
773 0, // size
774 false, // is_tlab
775 OldGen); // last_generation
776 }
777 }
778
779 bool GenCollectedHeap::is_in_young(oop p) {
780 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
781 assert(result == _young_gen->is_in_reserved(p),
782 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
783 return result;
784 }
785
786 // Returns "TRUE" iff "p" points into the committed areas of the heap.
787 bool GenCollectedHeap::is_in(const void* p) const {
788 return _young_gen->is_in(p) || _old_gen->is_in(p);
789 }
790
791 #ifdef ASSERT
792 // Don't implement this by using is_in_young(). This method is used
793 // in some cases to check that is_in_young() is correct.
794 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
795 assert(is_in_reserved(p) || p == NULL,
796 "Does not work if address is non-null and outside of the heap");
797 return p < _young_gen->reserved().end() && p != NULL;
798 }
799 #endif
800
801 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
802 NoHeaderExtendedOopClosure no_header_cl(cl);
803 oop_iterate(&no_header_cl);
804 }
805
806 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
807 _young_gen->oop_iterate(cl);
808 _old_gen->oop_iterate(cl);
809 }
810
811 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
812 _young_gen->object_iterate(cl);
813 _old_gen->object_iterate(cl);
814 }
815
816 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
817 _young_gen->safe_object_iterate(cl);
818 _old_gen->safe_object_iterate(cl);
819 }
820
821 Space* GenCollectedHeap::space_containing(const void* addr) const {
822 Space* res = _young_gen->space_containing(addr);
823 if (res != NULL) {
824 return res;
825 }
826 res = _old_gen->space_containing(addr);
827 assert(res != NULL, "Could not find containing space");
828 return res;
829 }
830
831 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
832 assert(is_in_reserved(addr), "block_start of address outside of heap");
833 if (_young_gen->is_in_reserved(addr)) {
834 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
835 return _young_gen->block_start(addr);
836 }
837
838 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
839 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
840 return _old_gen->block_start(addr);
841 }
842
843 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
844 assert(is_in_reserved(addr), "block_size of address outside of heap");
845 if (_young_gen->is_in_reserved(addr)) {
846 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
847 return _young_gen->block_size(addr);
848 }
849
850 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
851 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
852 return _old_gen->block_size(addr);
853 }
854
855 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
856 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
857 assert(block_start(addr) == addr, "addr must be a block start");
858 if (_young_gen->is_in_reserved(addr)) {
859 return _young_gen->block_is_obj(addr);
860 }
861
862 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
863 return _old_gen->block_is_obj(addr);
864 }
865
866 bool GenCollectedHeap::supports_tlab_allocation() const {
867 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
868 return _young_gen->supports_tlab_allocation();
869 }
870
871 size_t GenCollectedHeap::tlab_capacity(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_capacity();
875 }
876 return 0;
877 }
878
879 size_t GenCollectedHeap::tlab_used(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->tlab_used();
883 }
884 return 0;
885 }
886
887 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
888 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
889 if (_young_gen->supports_tlab_allocation()) {
890 return _young_gen->unsafe_max_tlab_alloc();
891 }
892 return 0;
893 }
894
895 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
896 bool gc_overhead_limit_was_exceeded;
897 return gen_policy()->mem_allocate_work(size /* size */,
898 true /* is_tlab */,
899 &gc_overhead_limit_was_exceeded);
900 }
901
902 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
903 // from the list headed by "*prev_ptr".
904 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
905 bool first = true;
906 size_t min_size = 0; // "first" makes this conceptually infinite.
907 ScratchBlock **smallest_ptr, *smallest;
908 ScratchBlock *cur = *prev_ptr;
909 while (cur) {
910 assert(*prev_ptr == cur, "just checking");
911 if (first || cur->num_words < min_size) {
912 smallest_ptr = prev_ptr;
913 smallest = cur;
914 min_size = smallest->num_words;
915 first = false;
916 }
917 prev_ptr = &cur->next;
918 cur = cur->next;
919 }
920 smallest = *smallest_ptr;
921 *smallest_ptr = smallest->next;
922 return smallest;
923 }
924
925 // Sort the scratch block list headed by res into decreasing size order,
926 // and set "res" to the result.
927 static void sort_scratch_list(ScratchBlock*& list) {
928 ScratchBlock* sorted = NULL;
929 ScratchBlock* unsorted = list;
930 while (unsorted) {
931 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
932 smallest->next = sorted;
933 sorted = smallest;
934 }
935 list = sorted;
936 }
937
938 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
939 size_t max_alloc_words) {
940 ScratchBlock* res = NULL;
941 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
942 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
943 sort_scratch_list(res);
944 return res;
945 }
946
947 void GenCollectedHeap::release_scratch() {
948 _young_gen->reset_scratch();
949 _old_gen->reset_scratch();
950 }
951
952 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
953 void do_generation(Generation* gen) {
954 gen->prepare_for_verify();
955 }
956 };
957
958 void GenCollectedHeap::prepare_for_verify() {
959 ensure_parsability(false); // no need to retire TLABs
960 GenPrepareForVerifyClosure blk;
961 generation_iterate(&blk, false);
962 }
963
964 void GenCollectedHeap::generation_iterate(GenClosure* cl,
965 bool old_to_young) {
966 if (old_to_young) {
967 cl->do_generation(_old_gen);
968 cl->do_generation(_young_gen);
969 } else {
970 cl->do_generation(_young_gen);
971 cl->do_generation(_old_gen);
972 }
973 }
974
975 bool GenCollectedHeap::is_maximal_no_gc() const {
976 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
977 }
978
979 void GenCollectedHeap::save_marks() {
980 _young_gen->save_marks();
981 _old_gen->save_marks();
982 }
983
984 GenCollectedHeap* GenCollectedHeap::heap() {
985 CollectedHeap* heap = Universe::heap();
986 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
987 assert(heap->kind() == CollectedHeap::GenCollectedHeap ||
988 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap");
989 return (GenCollectedHeap*) heap;
990 }
991
992 void GenCollectedHeap::prepare_for_compaction() {
993 // Start by compacting into same gen.
994 CompactPoint cp(_old_gen);
995 _old_gen->prepare_for_compaction(&cp);
996 _young_gen->prepare_for_compaction(&cp);
997 }
998
999 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1000 log_debug(gc, verify)("%s", _old_gen->name());
1001 _old_gen->verify();
1002
1003 log_debug(gc, verify)("%s", _old_gen->name());
1004 _young_gen->verify();
1005
1006 log_debug(gc, verify)("RemSet");
1007 rem_set()->verify();
1008 }
1009
1010 void GenCollectedHeap::print_on(outputStream* st) const {
1011 _young_gen->print_on(st);
1012 _old_gen->print_on(st);
1013 MetaspaceAux::print_on(st);
1014 }
1015
1016 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1017 }
1018
1019 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1020 }
1021
1022 void GenCollectedHeap::print_tracing_info() const {
1023 if (log_is_enabled(Debug, gc, heap, exit)) {
1024 LogStreamHandle(Debug, gc, heap, exit) lsh;
1025 _young_gen->print_summary_info_on(&lsh);
1026 _old_gen->print_summary_info_on(&lsh);
1027 }
1028 }
1029
1030 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1031 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1032 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1033 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1034 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1035 }
1036
1037 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1038 private:
1039 bool _full;
1040 public:
1041 void do_generation(Generation* gen) {
1042 gen->gc_prologue(_full);
1043 }
1044 GenGCPrologueClosure(bool full) : _full(full) {};
1045 };
1046
1047 void GenCollectedHeap::gc_prologue(bool full) {
1048 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1049
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 COMPILER2_OR_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_OR_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
1089 #ifndef PRODUCT
1090 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1091 private:
1092 public:
1093 void do_generation(Generation* gen) {
1094 gen->record_spaces_top();
1095 }
1096 };
1097
1098 void GenCollectedHeap::record_gen_tops_before_GC() {
1099 if (ZapUnusedHeapArea) {
1100 GenGCSaveTopsBeforeGCClosure blk;
1101 generation_iterate(&blk, false); // not old-to-young.
1102 }
1103 }
1104 #endif // not PRODUCT
1105
1106 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1107 public:
1108 void do_generation(Generation* gen) {
1109 gen->ensure_parsability();
1110 }
1111 };
1112
1113 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1114 CollectedHeap::ensure_parsability(retire_tlabs);
1115 GenEnsureParsabilityClosure ep_cl;
1116 generation_iterate(&ep_cl, false);
1117 }
1118
1119 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1120 oop obj,
1121 size_t obj_size) {
1122 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1123 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1124 HeapWord* result = NULL;
1125
1126 result = old_gen->expand_and_allocate(obj_size, false);
1127
1128 if (result != NULL) {
1129 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1130 }
1131 return oop(result);
1132 }
1133
1134 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1135 jlong _time; // in ms
1136 jlong _now; // in ms
1137
1138 public:
1139 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1140
1141 jlong time() { return _time; }
1142
1143 void do_generation(Generation* gen) {
1144 _time = MIN2(_time, gen->time_of_last_gc(_now));
1145 }
1146 };
1147
1148 jlong GenCollectedHeap::millis_since_last_gc() {
1149 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1150 // provided the underlying platform provides such a time source
1151 // (and it is bug free). So we still have to guard against getting
1152 // back a time later than 'now'.
1153 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1154 GenTimeOfLastGCClosure tolgc_cl(now);
1155 // iterate over generations getting the oldest
1156 // time that a generation was collected
1157 generation_iterate(&tolgc_cl, false);
1158
1159 jlong retVal = now - tolgc_cl.time();
1160 if (retVal < 0) {
1161 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1162 ". returning zero instead.", retVal);
1163 return 0;
1164 }
1165 return retVal;
1166 }