1 /*
2 * Copyright (c) 2001, 2024, 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 "cds/cdsConfig.hpp"
27 #include "classfile/classLoaderData.hpp"
28 #include "classfile/vmClasses.hpp"
29 #include "gc/shared/allocTracer.hpp"
30 #include "gc/shared/barrierSet.hpp"
31 #include "gc/shared/collectedHeap.hpp"
32 #include "gc/shared/collectedHeap.inline.hpp"
33 #include "gc/shared/gcLocker.inline.hpp"
34 #include "gc/shared/gcHeapSummary.hpp"
35 #include "gc/shared/stringdedup/stringDedup.hpp"
36 #include "gc/shared/gcTrace.hpp"
37 #include "gc/shared/gcTraceTime.inline.hpp"
38 #include "gc/shared/gcVMOperations.hpp"
39 #include "gc/shared/gcWhen.hpp"
40 #include "gc/shared/gc_globals.hpp"
41 #include "gc/shared/memAllocator.hpp"
42 #include "gc/shared/tlab_globals.hpp"
43 #include "logging/log.hpp"
44 #include "logging/logStream.hpp"
45 #include "memory/classLoaderMetaspace.hpp"
46 #include "memory/metaspace.hpp"
47 #include "memory/metaspaceUtils.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.hpp"
50 #include "oops/instanceMirrorKlass.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "runtime/handles.inline.hpp"
53 #include "runtime/init.hpp"
54 #include "runtime/javaThread.hpp"
55 #include "runtime/perfData.hpp"
56 #include "runtime/threadSMR.hpp"
57 #include "runtime/vmThread.hpp"
58 #include "services/heapDumper.hpp"
59 #include "utilities/align.hpp"
60 #include "utilities/copy.hpp"
61 #include "utilities/events.hpp"
62
63 class ClassLoaderData;
64
65 size_t CollectedHeap::_lab_alignment_reserve = SIZE_MAX;
66 Klass* CollectedHeap::_filler_object_klass = nullptr;
67 size_t CollectedHeap::_filler_array_max_size = 0;
68 size_t CollectedHeap::_stack_chunk_max_size = 0;
69
70 class GCMessage : public FormatBuffer<1024> {
71 public:
72 bool is_before;
73 };
74
75 template <>
76 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
77 st->print_cr("GC heap %s", m.is_before ? "before" : "after");
78 st->print_raw(m);
79 }
80
81 class GCHeapLog : public EventLogBase<GCMessage> {
82 private:
83 void log_heap(CollectedHeap* heap, bool before);
84
85 public:
86 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
87
88 void log_heap_before(CollectedHeap* heap) {
89 log_heap(heap, true);
90 }
91 void log_heap_after(CollectedHeap* heap) {
92 log_heap(heap, false);
93 }
94 };
95
96 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
97 if (!should_log()) {
98 return;
99 }
100
101 double timestamp = fetch_timestamp();
102 MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag);
103 int index = compute_log_index();
104 _records[index].thread = nullptr; // Its the GC thread so it's not that interesting.
105 _records[index].timestamp = timestamp;
106 _records[index].data.is_before = before;
107 stringStream st(_records[index].data.buffer(), _records[index].data.size());
108
109 st.print_cr("{Heap %s GC invocations=%u (full %u):",
110 before ? "before" : "after",
111 heap->total_collections(),
112 heap->total_full_collections());
113
114 heap->print_on(&st);
115 st.print_cr("}");
116 }
117
118 ParallelObjectIterator::ParallelObjectIterator(uint thread_num) :
119 _impl(Universe::heap()->parallel_object_iterator(thread_num))
120 {}
121
122 ParallelObjectIterator::~ParallelObjectIterator() {
123 delete _impl;
124 }
125
126 void ParallelObjectIterator::object_iterate(ObjectClosure* cl, uint worker_id) {
127 _impl->object_iterate(cl, worker_id);
128 }
129
130 size_t CollectedHeap::unused() const {
131 MutexLocker ml(Heap_lock);
132 return capacity() - used();
133 }
134
135 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
136 size_t capacity_in_words = capacity() / HeapWordSize;
137
138 return VirtualSpaceSummary(
139 _reserved.start(), _reserved.start() + capacity_in_words, _reserved.end());
140 }
141
142 GCHeapSummary CollectedHeap::create_heap_summary() {
143 VirtualSpaceSummary heap_space = create_heap_space_summary();
144 return GCHeapSummary(heap_space, used());
145 }
146
147 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
148 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
149 MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
150 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
151 MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
152 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(),
153 MetaspaceUtils::get_combined_statistics(),
154 ms_chunk_free_list_summary, class_chunk_free_list_summary);
155 }
156
157 bool CollectedHeap::contains_null(const oop* p) const {
158 return *p == nullptr;
159 }
160
161 void CollectedHeap::print_heap_before_gc() {
162 LogTarget(Debug, gc, heap) lt;
163 if (lt.is_enabled()) {
164 LogStream ls(lt);
165 ls.print_cr("Heap before GC invocations=%u (full %u):", total_collections(), total_full_collections());
166 ResourceMark rm;
167 print_on(&ls);
168 }
169
170 if (_gc_heap_log != nullptr) {
171 _gc_heap_log->log_heap_before(this);
172 }
173 }
174
175 void CollectedHeap::print_heap_after_gc() {
176 LogTarget(Debug, gc, heap) lt;
177 if (lt.is_enabled()) {
178 LogStream ls(lt);
179 ls.print_cr("Heap after GC invocations=%u (full %u):", total_collections(), total_full_collections());
180 ResourceMark rm;
181 print_on(&ls);
182 }
183
184 if (_gc_heap_log != nullptr) {
185 _gc_heap_log->log_heap_after(this);
186 }
187 }
188
189 void CollectedHeap::print() const { print_on(tty); }
190
191 void CollectedHeap::print_on_error(outputStream* st) const {
192 st->print_cr("Heap:");
193 print_extended_on(st);
194 st->cr();
195
196 BarrierSet* bs = BarrierSet::barrier_set();
197 if (bs != nullptr) {
198 bs->print_on(st);
199 }
200 }
201
202 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
203 const GCHeapSummary& heap_summary = create_heap_summary();
204 gc_tracer->report_gc_heap_summary(when, heap_summary);
205
206 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
207 gc_tracer->report_metaspace_summary(when, metaspace_summary);
208 }
209
210 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
211 trace_heap(GCWhen::BeforeGC, gc_tracer);
212 }
213
214 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
215 trace_heap(GCWhen::AfterGC, gc_tracer);
216 }
217
218 // Default implementation, for collectors that don't support the feature.
219 bool CollectedHeap::supports_concurrent_gc_breakpoints() const {
220 return false;
221 }
222
223 bool CollectedHeap::is_oop(oop object) const {
224 if (!is_object_aligned(object)) {
225 return false;
226 }
227
228 if (!is_in(object)) {
229 return false;
230 }
231
232 if (!Metaspace::contains(object->klass_without_asserts())) {
233 return false;
234 }
235
236 return true;
237 }
238
239 // Memory state functions.
240
241
242 CollectedHeap::CollectedHeap() :
243 _capacity_at_last_gc(0),
244 _used_at_last_gc(0),
245 _soft_ref_policy(),
246 _is_stw_gc_active(false),
247 _last_whole_heap_examined_time_ns(os::javaTimeNanos()),
248 _total_collections(0),
249 _total_full_collections(0),
250 _gc_cause(GCCause::_no_gc),
251 _gc_lastcause(GCCause::_no_gc)
252 {
253 // If the minimum object size is greater than MinObjAlignment, we can
254 // end up with a shard at the end of the buffer that's smaller than
255 // the smallest object. We can't allow that because the buffer must
256 // look like it's full of objects when we retire it, so we make
257 // sure we have enough space for a filler int array object.
258 size_t min_size = min_dummy_object_size();
259 _lab_alignment_reserve = min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0;
260
261 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
262 const size_t elements_per_word = HeapWordSize / sizeof(jint);
263 _filler_array_max_size = align_object_size(filler_array_hdr_size() +
264 max_len / elements_per_word);
265
266 NOT_PRODUCT(_promotion_failure_alot_count = 0;)
267 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
268
269 if (UsePerfData) {
270 EXCEPTION_MARK;
271
272 // create the gc cause jvmstat counters
273 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
274 80, GCCause::to_string(_gc_cause), CHECK);
275
276 _perf_gc_lastcause =
277 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
278 80, GCCause::to_string(_gc_lastcause), CHECK);
279 }
280
281 // Create the ring log
282 if (LogEvents) {
283 _gc_heap_log = new GCHeapLog();
284 } else {
285 _gc_heap_log = nullptr;
286 }
287 }
288
289 // This interface assumes that it's being called by the
290 // vm thread. It collects the heap assuming that the
291 // heap lock is already held and that we are executing in
292 // the context of the vm thread.
293 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
294 Thread* thread = Thread::current();
295 assert(thread->is_VM_thread(), "Precondition#1");
296 assert(Heap_lock->is_locked(), "Precondition#2");
297 GCCauseSetter gcs(this, cause);
298 switch (cause) {
299 case GCCause::_codecache_GC_threshold:
300 case GCCause::_codecache_GC_aggressive:
301 case GCCause::_heap_inspection:
302 case GCCause::_heap_dump:
303 case GCCause::_metadata_GC_threshold: {
304 HandleMark hm(thread);
305 do_full_collection(false); // don't clear all soft refs
306 break;
307 }
308 case GCCause::_metadata_GC_clear_soft_refs: {
309 HandleMark hm(thread);
310 do_full_collection(true); // do clear all soft refs
311 break;
312 }
313 default:
314 ShouldNotReachHere(); // Unexpected use of this function
315 }
316 }
317
318 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
319 size_t word_size,
320 Metaspace::MetadataType mdtype) {
321 uint loop_count = 0;
322 uint gc_count = 0;
323 uint full_gc_count = 0;
324
325 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
326
327 do {
328 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
329 if (result != nullptr) {
330 return result;
331 }
332
333 if (GCLocker::is_active_and_needs_gc()) {
334 // If the GCLocker is active, just expand and allocate.
335 // If that does not succeed, wait if this thread is not
336 // in a critical section itself.
337 result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
338 if (result != nullptr) {
339 return result;
340 }
341 JavaThread* jthr = JavaThread::current();
342 if (!jthr->in_critical()) {
343 // Wait for JNI critical section to be exited
344 GCLocker::stall_until_clear();
345 // The GC invoked by the last thread leaving the critical
346 // section will be a young collection and a full collection
347 // is (currently) needed for unloading classes so continue
348 // to the next iteration to get a full GC.
349 continue;
350 } else {
351 if (CheckJNICalls) {
352 fatal("Possible deadlock due to allocating while"
353 " in jni critical section");
354 }
355 return nullptr;
356 }
357 }
358
359 { // Need lock to get self consistent gc_count's
360 MutexLocker ml(Heap_lock);
361 gc_count = Universe::heap()->total_collections();
362 full_gc_count = Universe::heap()->total_full_collections();
363 }
364
365 // Generate a VM operation
366 VM_CollectForMetadataAllocation op(loader_data,
367 word_size,
368 mdtype,
369 gc_count,
370 full_gc_count,
371 GCCause::_metadata_GC_threshold);
372 VMThread::execute(&op);
373
374 // If GC was locked out, try again. Check before checking success because the
375 // prologue could have succeeded and the GC still have been locked out.
376 if (op.gc_locked()) {
377 continue;
378 }
379
380 if (op.prologue_succeeded()) {
381 return op.result();
382 }
383 loop_count++;
384 if ((QueuedAllocationWarningCount > 0) &&
385 (loop_count % QueuedAllocationWarningCount == 0)) {
386 log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
387 " size=" SIZE_FORMAT, loop_count, word_size);
388 }
389 } while (true); // Until a GC is done
390 }
391
392 MemoryUsage CollectedHeap::memory_usage() {
393 return MemoryUsage(InitialHeapSize, used(), capacity(), max_capacity());
394 }
395
396 void CollectedHeap::set_gc_cause(GCCause::Cause v) {
397 if (UsePerfData) {
398 _gc_lastcause = _gc_cause;
399 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
400 _perf_gc_cause->set_value(GCCause::to_string(v));
401 }
402 _gc_cause = v;
403 }
404
405 // Returns the header size in words aligned to the requirements of the
406 // array object type.
407 static int int_array_header_size() {
408 size_t typesize_in_bytes = arrayOopDesc::header_size_in_bytes();
409 return (int)align_up(typesize_in_bytes, HeapWordSize)/HeapWordSize;
410 }
411
412 size_t CollectedHeap::max_tlab_size() const {
413 // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
414 // This restriction could be removed by enabling filling with multiple arrays.
415 // If we compute that the reasonable way as
416 // header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
417 // we'll overflow on the multiply, so we do the divide first.
418 // We actually lose a little by dividing first,
419 // but that just makes the TLAB somewhat smaller than the biggest array,
420 // which is fine, since we'll be able to fill that.
421 size_t max_int_size = int_array_header_size() +
422 sizeof(jint) *
423 ((juint) max_jint / (size_t) HeapWordSize);
424 return align_down(max_int_size, MinObjAlignment);
425 }
426
427 size_t CollectedHeap::filler_array_hdr_size() {
428 return align_object_offset(int_array_header_size()); // align to Long
429 }
430
431 size_t CollectedHeap::filler_array_min_size() {
432 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
433 }
434
435 void CollectedHeap::zap_filler_array_with(HeapWord* start, size_t words, juint value) {
436 Copy::fill_to_words(start + filler_array_hdr_size(),
437 words - filler_array_hdr_size(), value);
438 }
439
440 #ifdef ASSERT
441 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
442 {
443 assert(words >= min_fill_size(), "too small to fill");
444 assert(is_object_aligned(words), "unaligned size");
445 }
446
447 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
448 {
449 if (ZapFillerObjects && zap) {
450 zap_filler_array_with(start, words, 0XDEAFBABE);
451 }
452 }
453 #endif // ASSERT
454
455 void
456 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
457 {
458 assert(words >= filler_array_min_size(), "too small for an array");
459 assert(words <= filler_array_max_size(), "too big for a single object");
460
461 const size_t payload_size = words - filler_array_hdr_size();
462 const size_t len = payload_size * HeapWordSize / sizeof(jint);
463 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
464
465 ObjArrayAllocator allocator(Universe::fillerArrayKlass(), words, (int)len, /* do_zero */ false);
466 allocator.initialize(start);
467 if (CDSConfig::is_dumping_heap()) {
468 // This array is written into the CDS archive. Make sure it
469 // has deterministic contents.
470 zap_filler_array_with(start, words, 0);
471 } else {
472 DEBUG_ONLY(zap_filler_array(start, words, zap);)
473 }
474 }
475
476 void
477 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
478 {
479 assert(words <= filler_array_max_size(), "too big for a single object");
480
481 if (words >= filler_array_min_size()) {
482 fill_with_array(start, words, zap);
483 } else if (words > 0) {
484 assert(words == min_fill_size(), "unaligned size");
485 ObjAllocator allocator(CollectedHeap::filler_object_klass(), words);
486 allocator.initialize(start);
487 }
488 }
489
490 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
491 {
492 DEBUG_ONLY(fill_args_check(start, words);)
493 HandleMark hm(Thread::current()); // Free handles before leaving.
494 fill_with_object_impl(start, words, zap);
495 }
496
497 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
498 {
499 DEBUG_ONLY(fill_args_check(start, words);)
500 HandleMark hm(Thread::current()); // Free handles before leaving.
501
502 // Multiple objects may be required depending on the filler array maximum size. Fill
503 // the range up to that with objects that are filler_array_max_size sized. The
504 // remainder is filled with a single object.
505 const size_t min = min_fill_size();
506 const size_t max = filler_array_max_size();
507 while (words > max) {
508 const size_t cur = (words - max) >= min ? max : max - min;
509 fill_with_array(start, cur, zap);
510 start += cur;
511 words -= cur;
512 }
513
514 fill_with_object_impl(start, words, zap);
515 }
516
517 void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
518 CollectedHeap::fill_with_object(start, end, zap);
519 }
520
521 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
522 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
523 "Should only be called at a safepoint or at start-up");
524
525 ThreadLocalAllocStats stats;
526
527 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next();) {
528 BarrierSet::barrier_set()->make_parsable(thread);
529 if (UseTLAB) {
530 if (retire_tlabs) {
531 thread->tlab().retire(&stats);
532 } else {
533 thread->tlab().make_parsable();
534 }
535 }
536 }
537
538 stats.publish();
539 }
540
541 void CollectedHeap::resize_all_tlabs() {
542 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
543 "Should only resize tlabs at safepoint");
544
545 if (UseTLAB && ResizeTLAB) {
546 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
547 thread->tlab().resize();
548 }
549 }
550 }
551
552 jlong CollectedHeap::millis_since_last_whole_heap_examined() {
553 return (os::javaTimeNanos() - _last_whole_heap_examined_time_ns) / NANOSECS_PER_MILLISEC;
554 }
555
556 void CollectedHeap::record_whole_heap_examined_timestamp() {
557 _last_whole_heap_examined_time_ns = os::javaTimeNanos();
558 }
559
560 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
561 assert(timer != nullptr, "timer is null");
562 static uint count = 0;
563 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
564 if (FullGCHeapDumpLimit == 0 || count < FullGCHeapDumpLimit) {
565 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
566 HeapDumper::dump_heap();
567 count++;
568 }
569 }
570
571 LogTarget(Trace, gc, classhisto) lt;
572 if (lt.is_enabled()) {
573 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
574 ResourceMark rm;
575 LogStream ls(lt);
576 VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
577 inspector.doit();
578 }
579 }
580
581 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
582 full_gc_dump(timer, true);
583 }
584
585 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
586 full_gc_dump(timer, false);
587 }
588
589 void CollectedHeap::initialize_reserved_region(const ReservedHeapSpace& rs) {
590 // It is important to do this in a way such that concurrent readers can't
591 // temporarily think something is in the heap. (Seen this happen in asserts.)
592 _reserved.set_word_size(0);
593 _reserved.set_start((HeapWord*)rs.base());
594 _reserved.set_end((HeapWord*)rs.end());
595 }
596
597 void CollectedHeap::post_initialize() {
598 StringDedup::initialize();
599 initialize_serviceability();
600 }
601
602 #ifndef PRODUCT
603
604 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
605 // Access to count is not atomic; the value does not have to be exact.
606 if (PromotionFailureALot) {
607 const size_t gc_num = total_collections();
608 const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
609 if (elapsed_gcs >= PromotionFailureALotInterval) {
610 // Test for unsigned arithmetic wrap-around.
611 if (++*count >= PromotionFailureALotCount) {
612 *count = 0;
613 return true;
614 }
615 }
616 }
617 return false;
618 }
619
620 bool CollectedHeap::promotion_should_fail() {
621 return promotion_should_fail(&_promotion_failure_alot_count);
622 }
623
624 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
625 if (PromotionFailureALot) {
626 _promotion_failure_alot_gc_number = total_collections();
627 *count = 0;
628 }
629 }
630
631 void CollectedHeap::reset_promotion_should_fail() {
632 reset_promotion_should_fail(&_promotion_failure_alot_count);
633 }
634
635 #endif // #ifndef PRODUCT
636
637 // It's the caller's responsibility to ensure glitch-freedom
638 // (if required).
639 void CollectedHeap::update_capacity_and_used_at_gc() {
640 _capacity_at_last_gc = capacity();
641 _used_at_last_gc = used();
642 }