1 /*
2 * Copyright (c) 2000, 2018, 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/cardTableRS.hpp"
34 #include "gc/shared/collectedHeap.inline.hpp"
35 #include "gc/shared/collectorCounters.hpp"
36 #include "gc/shared/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/gcTrace.hpp"
39 #include "gc/shared/gcTraceTime.inline.hpp"
40 #include "gc/shared/genCollectedHeap.hpp"
41 #include "gc/shared/genOopClosures.inline.hpp"
42 #include "gc/shared/generationSpec.hpp"
43 #include "gc/shared/space.hpp"
44 #include "gc/shared/strongRootsScope.hpp"
45 #include "gc/shared/vmGCOperations.hpp"
46 #include "gc/shared/weakProcessor.hpp"
47 #include "gc/shared/workgroup.hpp"
48 #include "memory/filemap.hpp"
49 #include "memory/resourceArea.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "runtime/biasedLocking.hpp"
52 #include "runtime/handles.hpp"
53 #include "runtime/handles.inline.hpp"
54 #include "runtime/java.hpp"
55 #include "runtime/vmThread.hpp"
56 #include "services/management.hpp"
57 #include "services/memoryService.hpp"
58 #include "utilities/debug.hpp"
59 #include "utilities/formatBuffer.hpp"
60 #include "utilities/macros.hpp"
61 #include "utilities/stack.inline.hpp"
62 #include "utilities/vmError.hpp"
63
64 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
65 CollectedHeap(),
66 _rem_set(NULL),
67 _gen_policy(policy),
68 _soft_ref_gen_policy(),
69 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
70 _full_collections_completed(0)
71 {
72 assert(policy != NULL, "Sanity check");
73 }
74
75 jint GenCollectedHeap::initialize() {
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 = new CardTableRS(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 CollectedHeap::post_initialize();
147 ref_processing_init();
148 check_gen_kinds();
149 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
150
151 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
152 _old_gen->capacity(),
153 def_new_gen->from()->capacity());
154
155 _gen_policy->initialize_gc_policy_counters();
156 }
157
158 void GenCollectedHeap::ref_processing_init() {
159 _young_gen->ref_processor_init();
160 _old_gen->ref_processor_init();
161 }
162
163 size_t GenCollectedHeap::capacity() const {
164 return _young_gen->capacity() + _old_gen->capacity();
165 }
166
167 size_t GenCollectedHeap::used() const {
168 return _young_gen->used() + _old_gen->used();
169 }
170
171 void GenCollectedHeap::save_used_regions() {
172 _old_gen->save_used_region();
173 _young_gen->save_used_region();
174 }
175
176 size_t GenCollectedHeap::max_capacity() const {
177 return _young_gen->max_capacity() + _old_gen->max_capacity();
178 }
179
180 // Update the _full_collections_completed counter
181 // at the end of a stop-world full GC.
182 unsigned int GenCollectedHeap::update_full_collections_completed() {
183 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
184 assert(_full_collections_completed <= _total_full_collections,
185 "Can't complete more collections than were started");
186 _full_collections_completed = _total_full_collections;
187 ml.notify_all();
188 return _full_collections_completed;
189 }
190
191 // Update the _full_collections_completed counter, as appropriate,
192 // at the end of a concurrent GC cycle. Note the conditional update
193 // below to allow this method to be called by a concurrent collector
194 // without synchronizing in any manner with the VM thread (which
195 // may already have initiated a STW full collection "concurrently").
196 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
197 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
198 assert((_full_collections_completed <= _total_full_collections) &&
199 (count <= _total_full_collections),
200 "Can't complete more collections than were started");
201 if (count > _full_collections_completed) {
202 _full_collections_completed = count;
203 ml.notify_all();
204 }
205 return _full_collections_completed;
206 }
207
208 // Return true if any of the following is true:
209 // . the allocation won't fit into the current young gen heap
210 // . gc locker is occupied (jni critical section)
211 // . heap memory is tight -- the most recent previous collection
212 // was a full collection because a partial collection (would
213 // have) failed and is likely to fail again
214 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
215 size_t young_capacity = young_gen()->capacity_before_gc();
216 return (word_size > heap_word_size(young_capacity))
217 || GCLocker::is_active_and_needs_gc()
218 || incremental_collection_failed();
219 }
220
221 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
222 HeapWord* result = NULL;
223 if (old_gen()->should_allocate(size, is_tlab)) {
224 result = old_gen()->expand_and_allocate(size, is_tlab);
225 }
226 if (result == NULL) {
227 if (young_gen()->should_allocate(size, is_tlab)) {
228 result = young_gen()->expand_and_allocate(size, is_tlab);
229 }
230 }
231 assert(result == NULL || is_in_reserved(result), "result not in heap");
232 return result;
233 }
234
235 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
236 bool is_tlab,
237 bool* gc_overhead_limit_was_exceeded) {
238 debug_only(check_for_valid_allocation_state());
239 assert(no_gc_in_progress(), "Allocation during gc not allowed");
240
241 // In general gc_overhead_limit_was_exceeded should be false so
242 // set it so here and reset it to true only if the gc time
243 // limit is being exceeded as checked below.
244 *gc_overhead_limit_was_exceeded = false;
245
246 HeapWord* result = NULL;
247
248 // Loop until the allocation is satisfied, or unsatisfied after GC.
249 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
250 HandleMark hm; // Discard any handles allocated in each iteration.
251
252 // First allocation attempt is lock-free.
253 Generation *young = young_gen();
254 assert(young->supports_inline_contig_alloc(),
255 "Otherwise, must do alloc within heap lock");
256 if (young->should_allocate(size, is_tlab)) {
257 result = young->par_allocate(size, is_tlab);
258 if (result != NULL) {
259 assert(is_in_reserved(result), "result not in heap");
260 return result;
261 }
262 }
263 uint gc_count_before; // Read inside the Heap_lock locked region.
264 {
265 MutexLocker ml(Heap_lock);
266 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
267 // Note that only large objects get a shot at being
268 // allocated in later generations.
269 bool first_only = ! should_try_older_generation_allocation(size);
270
271 result = attempt_allocation(size, is_tlab, first_only);
272 if (result != NULL) {
273 assert(is_in_reserved(result), "result not in heap");
274 return result;
275 }
276
277 if (GCLocker::is_active_and_needs_gc()) {
278 if (is_tlab) {
279 return NULL; // Caller will retry allocating individual object.
280 }
281 if (!is_maximal_no_gc()) {
282 // Try and expand heap to satisfy request.
283 result = expand_heap_and_allocate(size, is_tlab);
284 // Result could be null if we are out of space.
285 if (result != NULL) {
286 return result;
287 }
288 }
289
290 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
291 return NULL; // We didn't get to do a GC and we didn't get any memory.
292 }
293
294 // If this thread is not in a jni critical section, we stall
295 // the requestor until the critical section has cleared and
296 // GC allowed. When the critical section clears, a GC is
297 // initiated by the last thread exiting the critical section; so
298 // we retry the allocation sequence from the beginning of the loop,
299 // rather than causing more, now probably unnecessary, GC attempts.
300 JavaThread* jthr = JavaThread::current();
301 if (!jthr->in_critical()) {
302 MutexUnlocker mul(Heap_lock);
303 // Wait for JNI critical section to be exited
304 GCLocker::stall_until_clear();
305 gclocker_stalled_count += 1;
306 continue;
307 } else {
308 if (CheckJNICalls) {
309 fatal("Possible deadlock due to allocating while"
310 " in jni critical section");
311 }
312 return NULL;
313 }
314 }
315
316 // Read the gc count while the heap lock is held.
317 gc_count_before = total_collections();
318 }
319
320 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
321 VMThread::execute(&op);
322 if (op.prologue_succeeded()) {
323 result = op.result();
324 if (op.gc_locked()) {
325 assert(result == NULL, "must be NULL if gc_locked() is true");
326 continue; // Retry and/or stall as necessary.
327 }
328
329 // Allocation has failed and a collection
330 // has been done. If the gc time limit was exceeded the
331 // this time, return NULL so that an out-of-memory
332 // will be thrown. Clear gc_overhead_limit_exceeded
333 // so that the overhead exceeded does not persist.
334
335 const bool limit_exceeded = gen_policy()->size_policy()->gc_overhead_limit_exceeded();
336 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
337
338 if (limit_exceeded && softrefs_clear) {
339 *gc_overhead_limit_was_exceeded = true;
340 gen_policy()->size_policy()->set_gc_overhead_limit_exceeded(false);
341 if (op.result() != NULL) {
342 CollectedHeap::fill_with_object(op.result(), size);
343 }
344 return NULL;
345 }
346 assert(result == NULL || is_in_reserved(result),
347 "result not in heap");
348 return result;
349 }
350
351 // Give a warning if we seem to be looping forever.
352 if ((QueuedAllocationWarningCount > 0) &&
353 (try_count % QueuedAllocationWarningCount == 0)) {
354 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
355 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
356 }
357 }
358 }
359
360 #ifndef PRODUCT
361 // Override of memory state checking method in CollectedHeap:
362 // Some collectors (CMS for example) can't have badHeapWordVal written
363 // in the first two words of an object. (For instance , in the case of
364 // CMS these words hold state used to synchronize between certain
365 // (concurrent) GC steps and direct allocating mutators.)
366 // The skip_header_HeapWords() method below, allows us to skip
367 // over the requisite number of HeapWord's. Note that (for
368 // generational collectors) this means that those many words are
369 // skipped in each object, irrespective of the generation in which
370 // that object lives. The resultant loss of precision seems to be
371 // harmless and the pain of avoiding that imprecision appears somewhat
372 // higher than we are prepared to pay for such rudimentary debugging
373 // support.
374 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
375 size_t size) {
376 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
377 // We are asked to check a size in HeapWords,
378 // but the memory is mangled in juint words.
379 juint* start = (juint*) (addr + skip_header_HeapWords());
380 juint* end = (juint*) (addr + size);
381 for (juint* slot = start; slot < end; slot += 1) {
382 assert(*slot == badHeapWordVal,
383 "Found non badHeapWordValue in pre-allocation check");
384 }
385 }
386 }
387 #endif
388
389 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
390 bool is_tlab,
391 bool first_only) {
392 HeapWord* res = NULL;
393
394 if (_young_gen->should_allocate(size, is_tlab)) {
395 res = _young_gen->allocate(size, is_tlab);
396 if (res != NULL || first_only) {
397 return res;
398 }
399 }
400
401 if (_old_gen->should_allocate(size, is_tlab)) {
402 res = _old_gen->allocate(size, is_tlab);
403 }
404
405 return res;
406 }
407
408 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
409 bool* gc_overhead_limit_was_exceeded) {
410 return mem_allocate_work(size,
411 false /* is_tlab */,
412 gc_overhead_limit_was_exceeded);
413 }
414
415 bool GenCollectedHeap::must_clear_all_soft_refs() {
416 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
417 _gc_cause == GCCause::_wb_full_gc;
418 }
419
420 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
421 bool is_tlab, bool run_verification, bool clear_soft_refs,
422 bool restore_marks_for_biased_locking) {
423 FormatBuffer<> title("Collect gen: %s", gen->short_name());
424 GCTraceTime(Trace, gc, phases) t1(title);
425 TraceCollectorStats tcs(gen->counters());
426 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
427
428 gen->stat_record()->invocations++;
429 gen->stat_record()->accumulated_time.start();
430
431 // Must be done anew before each collection because
432 // a previous collection will do mangling and will
433 // change top of some spaces.
434 record_gen_tops_before_GC();
435
436 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
437
438 if (run_verification && VerifyBeforeGC) {
439 HandleMark hm; // Discard invalid handles created during verification
440 Universe::verify("Before GC");
441 }
442 COMPILER2_PRESENT(DerivedPointerTable::clear());
443
444 if (restore_marks_for_biased_locking) {
445 // We perform this mark word preservation work lazily
446 // because it's only at this point that we know whether we
447 // absolutely have to do it; we want to avoid doing it for
448 // scavenge-only collections where it's unnecessary
449 BiasedLocking::preserve_marks();
450 }
451
452 // Do collection work
453 {
454 // Note on ref discovery: For what appear to be historical reasons,
455 // GCH enables and disabled (by enqueing) refs discovery.
456 // In the future this should be moved into the generation's
457 // collect method so that ref discovery and enqueueing concerns
458 // are local to a generation. The collect method could return
459 // an appropriate indication in the case that notification on
460 // the ref lock was needed. This will make the treatment of
461 // weak refs more uniform (and indeed remove such concerns
462 // from GCH). XXX
463
464 HandleMark hm; // Discard invalid handles created during gc
465 save_marks(); // save marks for all gens
466 // We want to discover references, but not process them yet.
467 // This mode is disabled in process_discovered_references if the
468 // generation does some collection work, or in
469 // enqueue_discovered_references if the generation returns
470 // without doing any work.
471 ReferenceProcessor* rp = gen->ref_processor();
472 // If the discovery of ("weak") refs in this generation is
473 // atomic wrt other collectors in this configuration, we
474 // are guaranteed to have empty discovered ref lists.
475 if (rp->discovery_is_atomic()) {
476 rp->enable_discovery();
477 rp->setup_policy(clear_soft_refs);
478 } else {
479 // collect() below will enable discovery as appropriate
480 }
481 gen->collect(full, clear_soft_refs, size, is_tlab);
482 if (!rp->enqueuing_is_done()) {
483 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q());
484 rp->enqueue_discovered_references(NULL, &pt);
485 pt.print_enqueue_phase();
486 } else {
487 rp->set_enqueuing_is_done(false);
488 }
489 rp->verify_no_references_recorded();
490 }
491
492 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
493
494 gen->stat_record()->accumulated_time.stop();
495
496 update_gc_stats(gen, full);
497
498 if (run_verification && VerifyAfterGC) {
499 HandleMark hm; // Discard invalid handles created during verification
500 Universe::verify("After GC");
501 }
502 }
503
504 void GenCollectedHeap::do_collection(bool full,
505 bool clear_all_soft_refs,
506 size_t size,
507 bool is_tlab,
508 GenerationType max_generation) {
509 ResourceMark rm;
510 DEBUG_ONLY(Thread* my_thread = Thread::current();)
511
512 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
513 assert(my_thread->is_VM_thread() ||
514 my_thread->is_ConcurrentGC_thread(),
515 "incorrect thread type capability");
516 assert(Heap_lock->is_locked(),
517 "the requesting thread should have the Heap_lock");
518 guarantee(!is_gc_active(), "collection is not reentrant");
519
520 if (GCLocker::check_active_before_gc()) {
521 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
522 }
523
524 GCIdMark gc_id_mark;
525
526 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
527 soft_ref_policy()->should_clear_all_soft_refs();
528
529 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
530
531 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
532
533 print_heap_before_gc();
534
535 {
536 FlagSetting fl(_is_gc_active, true);
537
538 bool complete = full && (max_generation == OldGen);
539 bool old_collects_young = complete && !ScavengeBeforeFullGC;
540 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
541
542 FormatBuffer<> gc_string("%s", "Pause ");
543 if (do_young_collection) {
544 gc_string.append("Young");
545 } else {
546 gc_string.append("Full");
547 }
548
549 GCTraceCPUTime tcpu;
550 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
551
552 gc_prologue(complete);
553 increment_total_collections(complete);
554
555 size_t young_prev_used = _young_gen->used();
556 size_t old_prev_used = _old_gen->used();
557
558 bool run_verification = total_collections() >= VerifyGCStartAt;
559
560 bool prepared_for_verification = false;
561 bool collected_old = false;
562
563 if (do_young_collection) {
564 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
565 prepare_for_verify();
566 prepared_for_verification = true;
567 }
568
569 collect_generation(_young_gen,
570 full,
571 size,
572 is_tlab,
573 run_verification && VerifyGCLevel <= 0,
574 do_clear_all_soft_refs,
575 false);
576
577 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
578 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
579 // Allocation request was met by young GC.
580 size = 0;
581 }
582 }
583
584 bool must_restore_marks_for_biased_locking = false;
585
586 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
587 if (!complete) {
588 // The full_collections increment was missed above.
589 increment_total_full_collections();
590 }
591
592 if (!prepared_for_verification && run_verification &&
593 VerifyGCLevel <= 1 && VerifyBeforeGC) {
594 prepare_for_verify();
595 }
596
597 if (do_young_collection) {
598 // We did a young GC. Need a new GC id for the old GC.
599 GCIdMark gc_id_mark;
600 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
601 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
602 } else {
603 // No young GC done. Use the same GC id as was set up earlier in this method.
604 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
605 }
606
607 must_restore_marks_for_biased_locking = true;
608 collected_old = true;
609 }
610
611 // Update "complete" boolean wrt what actually transpired --
612 // for instance, a promotion failure could have led to
613 // a whole heap collection.
614 complete = complete || collected_old;
615
616 print_heap_change(young_prev_used, old_prev_used);
617 MetaspaceAux::print_metaspace_change(metadata_prev_used);
618
619 // Adjust generation sizes.
620 if (collected_old) {
621 _old_gen->compute_new_size();
622 }
623 _young_gen->compute_new_size();
624
625 if (complete) {
626 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
627 ClassLoaderDataGraph::purge();
628 MetaspaceAux::verify_metrics();
629 // Resize the metaspace capacity after full collections
630 MetaspaceGC::compute_new_size();
631 update_full_collections_completed();
632 }
633
634 // Track memory usage and detect low memory after GC finishes
635 MemoryService::track_memory_usage();
636
637 gc_epilogue(complete);
638
639 if (must_restore_marks_for_biased_locking) {
640 BiasedLocking::restore_marks();
641 }
642 }
643
644 print_heap_after_gc();
645
646 #ifdef TRACESPINNING
647 ParallelTaskTerminator::print_termination_counts();
648 #endif
649 }
650
651 void GenCollectedHeap::register_nmethod(nmethod* nm) {
652 CodeCache::register_scavenge_root_nmethod(nm);
653 }
654
655 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
656 CodeCache::verify_scavenge_root_nmethod(nm);
657 }
658
659 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
660 GCCauseSetter x(this, GCCause::_allocation_failure);
661 HeapWord* result = NULL;
662
663 assert(size != 0, "Precondition violated");
664 if (GCLocker::is_active_and_needs_gc()) {
665 // GC locker is active; instead of a collection we will attempt
666 // to expand the heap, if there's room for expansion.
667 if (!is_maximal_no_gc()) {
668 result = expand_heap_and_allocate(size, is_tlab);
669 }
670 return result; // Could be null if we are out of space.
671 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
672 // Do an incremental collection.
673 do_collection(false, // full
674 false, // clear_all_soft_refs
675 size, // size
676 is_tlab, // is_tlab
677 GenCollectedHeap::OldGen); // max_generation
678 } else {
679 log_trace(gc)(" :: Trying full because partial may fail :: ");
680 // Try a full collection; see delta for bug id 6266275
681 // for the original code and why this has been simplified
682 // with from-space allocation criteria modified and
683 // such allocation moved out of the safepoint path.
684 do_collection(true, // full
685 false, // clear_all_soft_refs
686 size, // size
687 is_tlab, // is_tlab
688 GenCollectedHeap::OldGen); // max_generation
689 }
690
691 result = attempt_allocation(size, is_tlab, false /*first_only*/);
692
693 if (result != NULL) {
694 assert(is_in_reserved(result), "result not in heap");
695 return result;
696 }
697
698 // OK, collection failed, try expansion.
699 result = expand_heap_and_allocate(size, is_tlab);
700 if (result != NULL) {
701 return result;
702 }
703
704 // If we reach this point, we're really out of memory. Try every trick
705 // we can to reclaim memory. Force collection of soft references. Force
706 // a complete compaction of the heap. Any additional methods for finding
707 // free memory should be here, especially if they are expensive. If this
708 // attempt fails, an OOM exception will be thrown.
709 {
710 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
711
712 do_collection(true, // full
713 true, // clear_all_soft_refs
714 size, // size
715 is_tlab, // is_tlab
716 GenCollectedHeap::OldGen); // max_generation
717 }
718
719 result = attempt_allocation(size, is_tlab, false /* first_only */);
720 if (result != NULL) {
721 assert(is_in_reserved(result), "result not in heap");
722 return result;
723 }
724
725 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
726 "Flag should have been handled and cleared prior to this point");
727
728 // What else? We might try synchronous finalization later. If the total
729 // space available is large enough for the allocation, then a more
730 // complete compaction phase than we've tried so far might be
731 // appropriate.
732 return NULL;
733 }
734
735 #ifdef ASSERT
736 class AssertNonScavengableClosure: public OopClosure {
737 public:
738 virtual void do_oop(oop* p) {
739 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
740 "Referent should not be scavengable."); }
741 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
742 };
743 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
744 #endif
745
746 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
747 ScanningOption so,
748 OopClosure* strong_roots,
749 OopClosure* weak_roots,
750 CLDClosure* strong_cld_closure,
751 CLDClosure* weak_cld_closure,
752 CodeBlobToOopClosure* code_roots) {
753 // General roots.
754 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
755 assert(code_roots != NULL, "code root closure should always be set");
756 // _n_termination for _process_strong_tasks should be set up stream
757 // in a method not running in a GC worker. Otherwise the GC worker
758 // could be trying to change the termination condition while the task
759 // is executing in another GC worker.
760
761 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
762 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
763 }
764
765 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
766 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
767
768 bool is_par = scope->n_threads() > 1;
769 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
770
771 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
772 Universe::oops_do(strong_roots);
773 }
774 // Global (strong) JNI handles
775 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
776 JNIHandles::oops_do(strong_roots);
777 }
778
779 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
780 ObjectSynchronizer::oops_do(strong_roots);
781 }
782 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
783 Management::oops_do(strong_roots);
784 }
785 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
786 JvmtiExport::oops_do(strong_roots);
787 }
788 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
789 AOTLoader::oops_do(strong_roots);
790 }
791
792 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
793 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
794 }
795
796 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
797 if (so & SO_ScavengeCodeCache) {
798 assert(code_roots != NULL, "must supply closure for code cache");
799
800 // We only visit parts of the CodeCache when scavenging.
801 CodeCache::scavenge_root_nmethods_do(code_roots);
802 }
803 if (so & SO_AllCodeCache) {
804 assert(code_roots != NULL, "must supply closure for code cache");
805
806 // CMSCollector uses this to do intermediate-strength collections.
807 // We scan the entire code cache, since CodeCache::do_unloading is not called.
808 CodeCache::blobs_do(code_roots);
809 }
810 // Verify that the code cache contents are not subject to
811 // movement by a scavenging collection.
812 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
813 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
814 }
815 }
816
817 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
818 OopClosure* root_closure) {
819 assert(root_closure != NULL, "Must be set");
820 // All threads execute the following. A specific chunk of buckets
821 // from the StringTable are the individual tasks.
822 if (scope->n_threads() > 1) {
823 StringTable::possibly_parallel_oops_do(root_closure);
824 } else {
825 StringTable::oops_do(root_closure);
826 }
827 }
828
829 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
830 OopsInGenClosure* root_closure,
831 OopsInGenClosure* old_gen_closure,
832 CLDClosure* cld_closure) {
833 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
834
835 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
836 cld_closure, cld_closure, &mark_code_closure);
837 process_string_table_roots(scope, root_closure);
838
839 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
840 root_closure->reset_generation();
841 }
842
843 // When collection is parallel, all threads get to cooperate to do
844 // old generation scanning.
845 old_gen_closure->set_generation(_old_gen);
846 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
847 old_gen_closure->reset_generation();
848
849 _process_strong_tasks->all_tasks_completed(scope->n_threads());
850 }
851
852 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
853 bool is_adjust_phase,
854 ScanningOption so,
855 bool only_strong_roots,
856 OopsInGenClosure* root_closure,
857 CLDClosure* cld_closure) {
858 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
859 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
860 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
861
862 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
863 if (is_adjust_phase) {
864 // We never treat the string table as roots during marking
865 // for the full gc, so we only need to process it during
866 // the adjust phase.
867 process_string_table_roots(scope, root_closure);
868 }
869
870 _process_strong_tasks->all_tasks_completed(scope->n_threads());
871 }
872
873 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
874 WeakProcessor::oops_do(root_closure);
875 _young_gen->ref_processor()->weak_oops_do(root_closure);
876 _old_gen->ref_processor()->weak_oops_do(root_closure);
877 }
878
879 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
880 void GenCollectedHeap:: \
881 oop_since_save_marks_iterate(GenerationType gen, \
882 OopClosureType* cur, \
883 OopClosureType* older) { \
884 if (gen == YoungGen) { \
885 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
886 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
887 } else { \
888 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
889 } \
890 }
891
892 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
893
894 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
895
896 bool GenCollectedHeap::no_allocs_since_save_marks() {
897 return _young_gen->no_allocs_since_save_marks() &&
898 _old_gen->no_allocs_since_save_marks();
899 }
900
901 bool GenCollectedHeap::supports_inline_contig_alloc() const {
902 return _young_gen->supports_inline_contig_alloc();
903 }
904
905 HeapWord* volatile* GenCollectedHeap::top_addr() const {
906 return _young_gen->top_addr();
907 }
908
909 HeapWord** GenCollectedHeap::end_addr() const {
910 return _young_gen->end_addr();
911 }
912
913 // public collection interfaces
914
915 void GenCollectedHeap::collect(GCCause::Cause cause) {
916 if (cause == GCCause::_wb_young_gc) {
917 // Young collection for the WhiteBox API.
918 collect(cause, YoungGen);
919 } else {
920 #ifdef ASSERT
921 if (cause == GCCause::_scavenge_alot) {
922 // Young collection only.
923 collect(cause, YoungGen);
924 } else {
925 // Stop-the-world full collection.
926 collect(cause, OldGen);
927 }
928 #else
929 // Stop-the-world full collection.
930 collect(cause, OldGen);
931 #endif
932 }
933 }
934
935 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
936 // The caller doesn't have the Heap_lock
937 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
938 MutexLocker ml(Heap_lock);
939 collect_locked(cause, max_generation);
940 }
941
942 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
943 // The caller has the Heap_lock
944 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
945 collect_locked(cause, OldGen);
946 }
947
948 // this is the private collection interface
949 // The Heap_lock is expected to be held on entry.
950
951 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
952 // Read the GC count while holding the Heap_lock
953 unsigned int gc_count_before = total_collections();
954 unsigned int full_gc_count_before = total_full_collections();
955 {
956 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
957 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
958 cause, max_generation);
959 VMThread::execute(&op);
960 }
961 }
962
963 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
964 do_full_collection(clear_all_soft_refs, OldGen);
965 }
966
967 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
968 GenerationType last_generation) {
969 GenerationType local_last_generation;
970 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
971 gc_cause() == GCCause::_gc_locker) {
972 local_last_generation = YoungGen;
973 } else {
974 local_last_generation = last_generation;
975 }
976
977 do_collection(true, // full
978 clear_all_soft_refs, // clear_all_soft_refs
979 0, // size
980 false, // is_tlab
981 local_last_generation); // last_generation
982 // Hack XXX FIX ME !!!
983 // A scavenge may not have been attempted, or may have
984 // been attempted and failed, because the old gen was too full
985 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
986 incremental_collection_will_fail(false /* don't consult_young */)) {
987 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
988 // This time allow the old gen to be collected as well
989 do_collection(true, // full
990 clear_all_soft_refs, // clear_all_soft_refs
991 0, // size
992 false, // is_tlab
993 OldGen); // last_generation
994 }
995 }
996
997 bool GenCollectedHeap::is_in_young(oop p) {
998 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
999 assert(result == _young_gen->is_in_reserved(p),
1000 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1001 return result;
1002 }
1003
1004 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1005 bool GenCollectedHeap::is_in(const void* p) const {
1006 return _young_gen->is_in(p) || _old_gen->is_in(p);
1007 }
1008
1009 #ifdef ASSERT
1010 // Don't implement this by using is_in_young(). This method is used
1011 // in some cases to check that is_in_young() is correct.
1012 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1013 assert(is_in_reserved(p) || p == NULL,
1014 "Does not work if address is non-null and outside of the heap");
1015 return p < _young_gen->reserved().end() && p != NULL;
1016 }
1017 #endif
1018
1019 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
1020 NoHeaderExtendedOopClosure no_header_cl(cl);
1021 oop_iterate(&no_header_cl);
1022 }
1023
1024 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
1025 _young_gen->oop_iterate(cl);
1026 _old_gen->oop_iterate(cl);
1027 }
1028
1029 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1030 _young_gen->object_iterate(cl);
1031 _old_gen->object_iterate(cl);
1032 }
1033
1034 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1035 _young_gen->safe_object_iterate(cl);
1036 _old_gen->safe_object_iterate(cl);
1037 }
1038
1039 Space* GenCollectedHeap::space_containing(const void* addr) const {
1040 Space* res = _young_gen->space_containing(addr);
1041 if (res != NULL) {
1042 return res;
1043 }
1044 res = _old_gen->space_containing(addr);
1045 assert(res != NULL, "Could not find containing space");
1046 return res;
1047 }
1048
1049 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1050 assert(is_in_reserved(addr), "block_start of address outside of heap");
1051 if (_young_gen->is_in_reserved(addr)) {
1052 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1053 return _young_gen->block_start(addr);
1054 }
1055
1056 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1057 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1058 return _old_gen->block_start(addr);
1059 }
1060
1061 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1062 assert(is_in_reserved(addr), "block_size of address outside of heap");
1063 if (_young_gen->is_in_reserved(addr)) {
1064 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1065 return _young_gen->block_size(addr);
1066 }
1067
1068 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1069 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1070 return _old_gen->block_size(addr);
1071 }
1072
1073 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1074 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1075 assert(block_start(addr) == addr, "addr must be a block start");
1076 if (_young_gen->is_in_reserved(addr)) {
1077 return _young_gen->block_is_obj(addr);
1078 }
1079
1080 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1081 return _old_gen->block_is_obj(addr);
1082 }
1083
1084 bool GenCollectedHeap::supports_tlab_allocation() const {
1085 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1086 return _young_gen->supports_tlab_allocation();
1087 }
1088
1089 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1090 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1091 if (_young_gen->supports_tlab_allocation()) {
1092 return _young_gen->tlab_capacity();
1093 }
1094 return 0;
1095 }
1096
1097 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1098 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1099 if (_young_gen->supports_tlab_allocation()) {
1100 return _young_gen->tlab_used();
1101 }
1102 return 0;
1103 }
1104
1105 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1106 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1107 if (_young_gen->supports_tlab_allocation()) {
1108 return _young_gen->unsafe_max_tlab_alloc();
1109 }
1110 return 0;
1111 }
1112
1113 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1114 bool gc_overhead_limit_was_exceeded;
1115 return mem_allocate_work(size /* size */,
1116 true /* is_tlab */,
1117 &gc_overhead_limit_was_exceeded);
1118 }
1119
1120 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1121 // from the list headed by "*prev_ptr".
1122 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1123 bool first = true;
1124 size_t min_size = 0; // "first" makes this conceptually infinite.
1125 ScratchBlock **smallest_ptr, *smallest;
1126 ScratchBlock *cur = *prev_ptr;
1127 while (cur) {
1128 assert(*prev_ptr == cur, "just checking");
1129 if (first || cur->num_words < min_size) {
1130 smallest_ptr = prev_ptr;
1131 smallest = cur;
1132 min_size = smallest->num_words;
1133 first = false;
1134 }
1135 prev_ptr = &cur->next;
1136 cur = cur->next;
1137 }
1138 smallest = *smallest_ptr;
1139 *smallest_ptr = smallest->next;
1140 return smallest;
1141 }
1142
1143 // Sort the scratch block list headed by res into decreasing size order,
1144 // and set "res" to the result.
1145 static void sort_scratch_list(ScratchBlock*& list) {
1146 ScratchBlock* sorted = NULL;
1147 ScratchBlock* unsorted = list;
1148 while (unsorted) {
1149 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1150 smallest->next = sorted;
1151 sorted = smallest;
1152 }
1153 list = sorted;
1154 }
1155
1156 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1157 size_t max_alloc_words) {
1158 ScratchBlock* res = NULL;
1159 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1160 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1161 sort_scratch_list(res);
1162 return res;
1163 }
1164
1165 void GenCollectedHeap::release_scratch() {
1166 _young_gen->reset_scratch();
1167 _old_gen->reset_scratch();
1168 }
1169
1170 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1171 void do_generation(Generation* gen) {
1172 gen->prepare_for_verify();
1173 }
1174 };
1175
1176 void GenCollectedHeap::prepare_for_verify() {
1177 ensure_parsability(false); // no need to retire TLABs
1178 GenPrepareForVerifyClosure blk;
1179 generation_iterate(&blk, false);
1180 }
1181
1182 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1183 bool old_to_young) {
1184 if (old_to_young) {
1185 cl->do_generation(_old_gen);
1186 cl->do_generation(_young_gen);
1187 } else {
1188 cl->do_generation(_young_gen);
1189 cl->do_generation(_old_gen);
1190 }
1191 }
1192
1193 bool GenCollectedHeap::is_maximal_no_gc() const {
1194 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1195 }
1196
1197 void GenCollectedHeap::save_marks() {
1198 _young_gen->save_marks();
1199 _old_gen->save_marks();
1200 }
1201
1202 GenCollectedHeap* GenCollectedHeap::heap() {
1203 CollectedHeap* heap = Universe::heap();
1204 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1205 assert(heap->kind() == CollectedHeap::SerialHeap ||
1206 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap");
1207 return (GenCollectedHeap*) heap;
1208 }
1209
1210 void GenCollectedHeap::prepare_for_compaction() {
1211 // Start by compacting into same gen.
1212 CompactPoint cp(_old_gen);
1213 _old_gen->prepare_for_compaction(&cp);
1214 _young_gen->prepare_for_compaction(&cp);
1215 }
1216
1217 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1218 log_debug(gc, verify)("%s", _old_gen->name());
1219 _old_gen->verify();
1220
1221 log_debug(gc, verify)("%s", _old_gen->name());
1222 _young_gen->verify();
1223
1224 log_debug(gc, verify)("RemSet");
1225 rem_set()->verify();
1226 }
1227
1228 void GenCollectedHeap::print_on(outputStream* st) const {
1229 _young_gen->print_on(st);
1230 _old_gen->print_on(st);
1231 MetaspaceAux::print_on(st);
1232 }
1233
1234 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1235 }
1236
1237 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1238 }
1239
1240 void GenCollectedHeap::print_tracing_info() const {
1241 if (log_is_enabled(Debug, gc, heap, exit)) {
1242 LogStreamHandle(Debug, gc, heap, exit) lsh;
1243 _young_gen->print_summary_info_on(&lsh);
1244 _old_gen->print_summary_info_on(&lsh);
1245 }
1246 }
1247
1248 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1249 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1250 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1251 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1252 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1253 }
1254
1255 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1256 private:
1257 bool _full;
1258 public:
1259 void do_generation(Generation* gen) {
1260 gen->gc_prologue(_full);
1261 }
1262 GenGCPrologueClosure(bool full) : _full(full) {};
1263 };
1264
1265 void GenCollectedHeap::gc_prologue(bool full) {
1266 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1267
1268 // Fill TLAB's and such
1269 CollectedHeap::accumulate_statistics_all_tlabs();
1270 ensure_parsability(true); // retire TLABs
1271
1272 // Walk generations
1273 GenGCPrologueClosure blk(full);
1274 generation_iterate(&blk, false); // not old-to-young.
1275 };
1276
1277 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1278 private:
1279 bool _full;
1280 public:
1281 void do_generation(Generation* gen) {
1282 gen->gc_epilogue(_full);
1283 }
1284 GenGCEpilogueClosure(bool full) : _full(full) {};
1285 };
1286
1287 void GenCollectedHeap::gc_epilogue(bool full) {
1288 #if COMPILER2_OR_JVMCI
1289 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1290 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1291 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1292 #endif // COMPILER2_OR_JVMCI
1293
1294 resize_all_tlabs();
1295
1296 GenGCEpilogueClosure blk(full);
1297 generation_iterate(&blk, false); // not old-to-young.
1298
1299 if (!CleanChunkPoolAsync) {
1300 Chunk::clean_chunk_pool();
1301 }
1302
1303 MetaspaceCounters::update_performance_counters();
1304 CompressedClassSpaceCounters::update_performance_counters();
1305 };
1306
1307 #ifndef PRODUCT
1308 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1309 private:
1310 public:
1311 void do_generation(Generation* gen) {
1312 gen->record_spaces_top();
1313 }
1314 };
1315
1316 void GenCollectedHeap::record_gen_tops_before_GC() {
1317 if (ZapUnusedHeapArea) {
1318 GenGCSaveTopsBeforeGCClosure blk;
1319 generation_iterate(&blk, false); // not old-to-young.
1320 }
1321 }
1322 #endif // not PRODUCT
1323
1324 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1325 public:
1326 void do_generation(Generation* gen) {
1327 gen->ensure_parsability();
1328 }
1329 };
1330
1331 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1332 CollectedHeap::ensure_parsability(retire_tlabs);
1333 GenEnsureParsabilityClosure ep_cl;
1334 generation_iterate(&ep_cl, false);
1335 }
1336
1337 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1338 oop obj,
1339 size_t obj_size) {
1340 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1341 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1342 HeapWord* result = NULL;
1343
1344 result = old_gen->expand_and_allocate(obj_size, false);
1345
1346 if (result != NULL) {
1347 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1348 }
1349 return oop(result);
1350 }
1351
1352 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1353 jlong _time; // in ms
1354 jlong _now; // in ms
1355
1356 public:
1357 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1358
1359 jlong time() { return _time; }
1360
1361 void do_generation(Generation* gen) {
1362 _time = MIN2(_time, gen->time_of_last_gc(_now));
1363 }
1364 };
1365
1366 jlong GenCollectedHeap::millis_since_last_gc() {
1367 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1368 // provided the underlying platform provides such a time source
1369 // (and it is bug free). So we still have to guard against getting
1370 // back a time later than 'now'.
1371 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1372 GenTimeOfLastGCClosure tolgc_cl(now);
1373 // iterate over generations getting the oldest
1374 // time that a generation was collected
1375 generation_iterate(&tolgc_cl, false);
1376
1377 jlong retVal = now - tolgc_cl.time();
1378 if (retVal < 0) {
1379 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1380 ". returning zero instead.", retVal);
1381 return 0;
1382 }
1383 return retVal;
1384 }