1 /*
2 * Copyright (c) 2001, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderData.hpp"
27 #include "classfile/vmClasses.hpp"
28 #include "gc/shared/allocTracer.hpp"
29 #include "gc/shared/barrierSet.hpp"
30 #include "gc/shared/collectedHeap.hpp"
31 #include "gc/shared/collectedHeap.inline.hpp"
32 #include "gc/shared/gcLocker.inline.hpp"
33 #include "gc/shared/gcHeapSummary.hpp"
34 #include "gc/shared/stringdedup/stringDedup.hpp"
35 #include "gc/shared/gcTrace.hpp"
36 #include "gc/shared/gcTraceTime.inline.hpp"
37 #include "gc/shared/gcVMOperations.hpp"
38 #include "gc/shared/gcWhen.hpp"
39 #include "gc/shared/gc_globals.hpp"
40 #include "gc/shared/memAllocator.hpp"
41 #include "gc/shared/tlab_globals.hpp"
42 #include "logging/log.hpp"
43 #include "logging/logStream.hpp"
44 #include "memory/classLoaderMetaspace.hpp"
45 #include "memory/metaspace.hpp"
46 #include "memory/metaspaceUtils.hpp"
47 #include "memory/resourceArea.hpp"
48 #include "memory/universe.hpp"
49 #include "oops/instanceMirrorKlass.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "runtime/handles.inline.hpp"
52 #include "runtime/init.hpp"
53 #include "runtime/javaThread.hpp"
54 #include "runtime/perfData.hpp"
55 #include "runtime/threadSMR.hpp"
56 #include "runtime/vmThread.hpp"
57 #include "services/heapDumper.hpp"
58 #include "utilities/align.hpp"
59 #include "utilities/copy.hpp"
60 #include "utilities/events.hpp"
61
62 class ClassLoaderData;
63
64 size_t CollectedHeap::_lab_alignment_reserve = SIZE_MAX;
65 Klass* CollectedHeap::_filler_object_klass = nullptr;
66 size_t CollectedHeap::_filler_array_max_size = 0;
67 size_t CollectedHeap::_stack_chunk_max_size = 0;
68
69 class GCMessage : public FormatBuffer<1024> {
70 public:
71 bool is_before;
72 };
73
74 template <>
75 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
76 st->print_cr("GC heap %s", m.is_before ? "before" : "after");
77 st->print_raw(m);
78 }
79
80 class GCHeapLog : public EventLogBase<GCMessage> {
81 private:
82 void log_heap(CollectedHeap* heap, bool before);
83
84 public:
85 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
86
87 void log_heap_before(CollectedHeap* heap) {
88 log_heap(heap, true);
89 }
90 void log_heap_after(CollectedHeap* heap) {
91 log_heap(heap, false);
92 }
93 };
94
95 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
96 if (!should_log()) {
97 return;
98 }
99
100 double timestamp = fetch_timestamp();
101 MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag);
102 int index = compute_log_index();
103 _records[index].thread = nullptr; // Its the GC thread so it's not that interesting.
104 _records[index].timestamp = timestamp;
105 _records[index].data.is_before = before;
106 stringStream st(_records[index].data.buffer(), _records[index].data.size());
107
108 st.print_cr("{Heap %s GC invocations=%u (full %u):",
109 before ? "before" : "after",
110 heap->total_collections(),
111 heap->total_full_collections());
112
113 heap->print_on(&st);
114 st.print_cr("}");
115 }
116
117 ParallelObjectIterator::ParallelObjectIterator(uint thread_num) :
118 _impl(Universe::heap()->parallel_object_iterator(thread_num))
119 {}
120
121 ParallelObjectIterator::~ParallelObjectIterator() {
122 delete _impl;
123 }
124
125 void ParallelObjectIterator::object_iterate(ObjectClosure* cl, uint worker_id) {
126 _impl->object_iterate(cl, worker_id);
127 }
128
129 size_t CollectedHeap::unused() const {
130 MutexLocker ml(Heap_lock);
131 return capacity() - used();
132 }
133
134 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
135 size_t capacity_in_words = capacity() / HeapWordSize;
136
137 return VirtualSpaceSummary(
138 _reserved.start(), _reserved.start() + capacity_in_words, _reserved.end());
139 }
140
141 GCHeapSummary CollectedHeap::create_heap_summary() {
142 VirtualSpaceSummary heap_space = create_heap_space_summary();
143 return GCHeapSummary(heap_space, used());
144 }
145
146 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
147 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
148 MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
149 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
150 MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
151 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(),
152 MetaspaceUtils::get_combined_statistics(),
153 ms_chunk_free_list_summary, class_chunk_free_list_summary);
154 }
155
156 bool CollectedHeap::contains_null(const oop* p) const {
157 return *p == nullptr;
158 }
159
160 void CollectedHeap::print_heap_before_gc() {
161 LogTarget(Debug, gc, heap) lt;
162 if (lt.is_enabled()) {
163 LogStream ls(lt);
164 ls.print_cr("Heap before GC invocations=%u (full %u):", total_collections(), total_full_collections());
165 ResourceMark rm;
166 print_on(&ls);
167 }
168
169 if (_gc_heap_log != nullptr) {
170 _gc_heap_log->log_heap_before(this);
171 }
172 }
173
174 void CollectedHeap::print_heap_after_gc() {
175 LogTarget(Debug, gc, heap) lt;
176 if (lt.is_enabled()) {
177 LogStream ls(lt);
178 ls.print_cr("Heap after GC invocations=%u (full %u):", total_collections(), total_full_collections());
179 ResourceMark rm;
180 print_on(&ls);
181 }
182
183 if (_gc_heap_log != nullptr) {
184 _gc_heap_log->log_heap_after(this);
185 }
186 }
187
188 void CollectedHeap::print() const { print_on(tty); }
189
190 void CollectedHeap::print_on_error(outputStream* st) const {
191 st->print_cr("Heap:");
192 print_extended_on(st);
193 st->cr();
194
195 BarrierSet* bs = BarrierSet::barrier_set();
196 if (bs != nullptr) {
197 bs->print_on(st);
198 }
199 }
200
201 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
202 const GCHeapSummary& heap_summary = create_heap_summary();
203 gc_tracer->report_gc_heap_summary(when, heap_summary);
204
205 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
206 gc_tracer->report_metaspace_summary(when, metaspace_summary);
207 }
208
209 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
210 trace_heap(GCWhen::BeforeGC, gc_tracer);
211 }
212
213 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
214 trace_heap(GCWhen::AfterGC, gc_tracer);
215 }
216
217 // Default implementation, for collectors that don't support the feature.
218 bool CollectedHeap::supports_concurrent_gc_breakpoints() const {
219 return false;
220 }
221
222 bool CollectedHeap::is_oop(oop object) const {
223 if (!is_object_aligned(object)) {
224 return false;
225 }
226
227 if (!is_in(object)) {
228 return false;
229 }
230
231 if (!Metaspace::contains(object->klass_raw())) {
232 return false;
233 }
234
235 return true;
236 }
237
238 // Memory state functions.
239
240
241 CollectedHeap::CollectedHeap() :
242 _capacity_at_last_gc(0),
243 _used_at_last_gc(0),
244 _is_gc_active(false),
245 _last_whole_heap_examined_time_ns(os::javaTimeNanos()),
246 _total_collections(0),
247 _total_full_collections(0),
248 _gc_cause(GCCause::_no_gc),
249 _gc_lastcause(GCCause::_no_gc)
250 {
251 // If the minimum object size is greater than MinObjAlignment, we can
252 // end up with a shard at the end of the buffer that's smaller than
253 // the smallest object. We can't allow that because the buffer must
254 // look like it's full of objects when we retire it, so we make
255 // sure we have enough space for a filler int array object.
256 size_t min_size = min_dummy_object_size();
257 _lab_alignment_reserve = min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0;
258
259 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
260 const size_t elements_per_word = HeapWordSize / sizeof(jint);
261 _filler_array_max_size = align_object_size(filler_array_hdr_size() +
262 max_len / elements_per_word);
263
264 NOT_PRODUCT(_promotion_failure_alot_count = 0;)
265 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
266
267 if (UsePerfData) {
268 EXCEPTION_MARK;
269
270 // create the gc cause jvmstat counters
271 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
272 80, GCCause::to_string(_gc_cause), CHECK);
273
274 _perf_gc_lastcause =
275 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
276 80, GCCause::to_string(_gc_lastcause), CHECK);
277 }
278
279 // Create the ring log
280 if (LogEvents) {
281 _gc_heap_log = new GCHeapLog();
282 } else {
283 _gc_heap_log = nullptr;
284 }
285 }
286
287 // This interface assumes that it's being called by the
288 // vm thread. It collects the heap assuming that the
289 // heap lock is already held and that we are executing in
290 // the context of the vm thread.
291 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
292 Thread* thread = Thread::current();
293 assert(thread->is_VM_thread(), "Precondition#1");
294 assert(Heap_lock->is_locked(), "Precondition#2");
295 GCCauseSetter gcs(this, cause);
296 switch (cause) {
297 case GCCause::_codecache_GC_threshold:
298 case GCCause::_codecache_GC_aggressive:
299 case GCCause::_heap_inspection:
300 case GCCause::_heap_dump:
301 case GCCause::_metadata_GC_threshold: {
302 HandleMark hm(thread);
303 do_full_collection(false); // don't clear all soft refs
304 break;
305 }
306 case GCCause::_metadata_GC_clear_soft_refs: {
307 HandleMark hm(thread);
308 do_full_collection(true); // do clear all soft refs
309 break;
310 }
311 default:
312 ShouldNotReachHere(); // Unexpected use of this function
313 }
314 }
315
316 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
317 size_t word_size,
318 Metaspace::MetadataType mdtype) {
319 uint loop_count = 0;
320 uint gc_count = 0;
321 uint full_gc_count = 0;
322
323 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
324
325 do {
326 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
327 if (result != nullptr) {
328 return result;
329 }
330
331 if (GCLocker::is_active_and_needs_gc()) {
332 // If the GCLocker is active, just expand and allocate.
333 // If that does not succeed, wait if this thread is not
334 // in a critical section itself.
335 result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
336 if (result != nullptr) {
337 return result;
338 }
339 JavaThread* jthr = JavaThread::current();
340 if (!jthr->in_critical()) {
341 // Wait for JNI critical section to be exited
342 GCLocker::stall_until_clear();
343 // The GC invoked by the last thread leaving the critical
344 // section will be a young collection and a full collection
345 // is (currently) needed for unloading classes so continue
346 // to the next iteration to get a full GC.
347 continue;
348 } else {
349 if (CheckJNICalls) {
350 fatal("Possible deadlock due to allocating while"
351 " in jni critical section");
352 }
353 return nullptr;
354 }
355 }
356
357 { // Need lock to get self consistent gc_count's
358 MutexLocker ml(Heap_lock);
359 gc_count = Universe::heap()->total_collections();
360 full_gc_count = Universe::heap()->total_full_collections();
361 }
362
363 // Generate a VM operation
364 VM_CollectForMetadataAllocation op(loader_data,
365 word_size,
366 mdtype,
367 gc_count,
368 full_gc_count,
369 GCCause::_metadata_GC_threshold);
370 VMThread::execute(&op);
371
372 // If GC was locked out, try again. Check before checking success because the
373 // prologue could have succeeded and the GC still have been locked out.
374 if (op.gc_locked()) {
375 continue;
376 }
377
378 if (op.prologue_succeeded()) {
379 return op.result();
380 }
381 loop_count++;
382 if ((QueuedAllocationWarningCount > 0) &&
383 (loop_count % QueuedAllocationWarningCount == 0)) {
384 log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
385 " size=" SIZE_FORMAT, loop_count, word_size);
386 }
387 } while (true); // Until a GC is done
388 }
389
390 MemoryUsage CollectedHeap::memory_usage() {
391 return MemoryUsage(InitialHeapSize, used(), capacity(), max_capacity());
392 }
393
394 void CollectedHeap::set_gc_cause(GCCause::Cause v) {
395 if (UsePerfData) {
396 _gc_lastcause = _gc_cause;
397 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
398 _perf_gc_cause->set_value(GCCause::to_string(v));
399 }
400 _gc_cause = v;
401 }
402
403 size_t CollectedHeap::max_tlab_size() const {
404 // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
405 // This restriction could be removed by enabling filling with multiple arrays.
406 // If we compute that the reasonable way as
407 // header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
408 // we'll overflow on the multiply, so we do the divide first.
409 // We actually lose a little by dividing first,
410 // but that just makes the TLAB somewhat smaller than the biggest array,
411 // which is fine, since we'll be able to fill that.
412 size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
413 sizeof(jint) *
414 ((juint) max_jint / (size_t) HeapWordSize);
415 return align_down(max_int_size, MinObjAlignment);
416 }
417
418 size_t CollectedHeap::filler_array_hdr_size() {
419 return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
420 }
421
422 size_t CollectedHeap::filler_array_min_size() {
423 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
424 }
425
426 void CollectedHeap::zap_filler_array_with(HeapWord* start, size_t words, juint value) {
427 Copy::fill_to_words(start + filler_array_hdr_size(),
428 words - filler_array_hdr_size(), value);
429 }
430
431 #ifdef ASSERT
432 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
433 {
434 assert(words >= min_fill_size(), "too small to fill");
435 assert(is_object_aligned(words), "unaligned size");
436 }
437
438 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
439 {
440 if (ZapFillerObjects && zap) {
441 zap_filler_array_with(start, words, 0XDEAFBABE);
442 }
443 }
444 #endif // ASSERT
445
446 void
447 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
448 {
449 assert(words >= filler_array_min_size(), "too small for an array");
450 assert(words <= filler_array_max_size(), "too big for a single object");
451
452 const size_t payload_size = words - filler_array_hdr_size();
453 const size_t len = payload_size * HeapWordSize / sizeof(jint);
454 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
455
456 ObjArrayAllocator allocator(Universe::fillerArrayKlassObj(), words, (int)len, /* do_zero */ false);
457 allocator.initialize(start);
458 if (DumpSharedSpaces) {
459 // This array is written into the CDS archive. Make sure it
460 // has deterministic contents.
461 zap_filler_array_with(start, words, 0);
462 } else {
463 DEBUG_ONLY(zap_filler_array(start, words, zap);)
464 }
465 }
466
467 void
468 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
469 {
470 assert(words <= filler_array_max_size(), "too big for a single object");
471
472 if (words >= filler_array_min_size()) {
473 fill_with_array(start, words, zap);
474 } else if (words > 0) {
475 assert(words == min_fill_size(), "unaligned size");
476 ObjAllocator allocator(CollectedHeap::filler_object_klass(), words);
477 allocator.initialize(start);
478 }
479 }
480
481 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
482 {
483 DEBUG_ONLY(fill_args_check(start, words);)
484 HandleMark hm(Thread::current()); // Free handles before leaving.
485 fill_with_object_impl(start, words, zap);
486 }
487
488 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
489 {
490 DEBUG_ONLY(fill_args_check(start, words);)
491 HandleMark hm(Thread::current()); // Free handles before leaving.
492
493 // Multiple objects may be required depending on the filler array maximum size. Fill
494 // the range up to that with objects that are filler_array_max_size sized. The
495 // remainder is filled with a single object.
496 const size_t min = min_fill_size();
497 const size_t max = filler_array_max_size();
498 while (words > max) {
499 const size_t cur = (words - max) >= min ? max : max - min;
500 fill_with_array(start, cur, zap);
501 start += cur;
502 words -= cur;
503 }
504
505 fill_with_object_impl(start, words, zap);
506 }
507
508 void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
509 CollectedHeap::fill_with_object(start, end, zap);
510 }
511
512 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
513 size_t requested_size,
514 size_t* actual_size) {
515 guarantee(false, "thread-local allocation buffers not supported");
516 return nullptr;
517 }
518
519 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
520 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
521 "Should only be called at a safepoint or at start-up");
522
523 ThreadLocalAllocStats stats;
524
525 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next();) {
526 BarrierSet::barrier_set()->make_parsable(thread);
527 if (UseTLAB) {
528 if (retire_tlabs) {
529 thread->tlab().retire(&stats);
530 } else {
531 thread->tlab().make_parsable();
532 }
533 }
534 }
535
536 stats.publish();
537 }
538
539 void CollectedHeap::resize_all_tlabs() {
540 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
541 "Should only resize tlabs at safepoint");
542
543 if (UseTLAB && ResizeTLAB) {
544 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
545 thread->tlab().resize();
546 }
547 }
548 }
549
550 jlong CollectedHeap::millis_since_last_whole_heap_examined() {
551 return (os::javaTimeNanos() - _last_whole_heap_examined_time_ns) / NANOSECS_PER_MILLISEC;
552 }
553
554 void CollectedHeap::record_whole_heap_examined_timestamp() {
555 _last_whole_heap_examined_time_ns = os::javaTimeNanos();
556 }
557
558 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
559 assert(timer != nullptr, "timer is null");
560 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
561 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
562 HeapDumper::dump_heap();
563 }
564
565 LogTarget(Trace, gc, classhisto) lt;
566 if (lt.is_enabled()) {
567 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
568 ResourceMark rm;
569 LogStream ls(lt);
570 VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
571 inspector.doit();
572 }
573 }
574
575 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
576 full_gc_dump(timer, true);
577 }
578
579 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
580 full_gc_dump(timer, false);
581 }
582
583 void CollectedHeap::initialize_reserved_region(const ReservedHeapSpace& rs) {
584 // It is important to do this in a way such that concurrent readers can't
585 // temporarily think something is in the heap. (Seen this happen in asserts.)
586 _reserved.set_word_size(0);
587 _reserved.set_start((HeapWord*)rs.base());
588 _reserved.set_end((HeapWord*)rs.end());
589 }
590
591 void CollectedHeap::post_initialize() {
592 StringDedup::initialize();
593 initialize_serviceability();
594 }
595
596 #ifndef PRODUCT
597
598 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
599 // Access to count is not atomic; the value does not have to be exact.
600 if (PromotionFailureALot) {
601 const size_t gc_num = total_collections();
602 const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
603 if (elapsed_gcs >= PromotionFailureALotInterval) {
604 // Test for unsigned arithmetic wrap-around.
605 if (++*count >= PromotionFailureALotCount) {
606 *count = 0;
607 return true;
608 }
609 }
610 }
611 return false;
612 }
613
614 bool CollectedHeap::promotion_should_fail() {
615 return promotion_should_fail(&_promotion_failure_alot_count);
616 }
617
618 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
619 if (PromotionFailureALot) {
620 _promotion_failure_alot_gc_number = total_collections();
621 *count = 0;
622 }
623 }
624
625 void CollectedHeap::reset_promotion_should_fail() {
626 reset_promotion_should_fail(&_promotion_failure_alot_count);
627 }
628
629 #endif // #ifndef PRODUCT
630
631 // It's the caller's responsibility to ensure glitch-freedom
632 // (if required).
633 void CollectedHeap::update_capacity_and_used_at_gc() {
634 _capacity_at_last_gc = capacity();
635 _used_at_last_gc = used();
636 }