1 /*
2 * Copyright (c) 2001, 2021, 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/metaspaceUtils.hpp"
46 #include "memory/resourceArea.hpp"
47 #include "memory/universe.hpp"
48 #include "oops/instanceMirrorKlass.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "runtime/handles.inline.hpp"
51 #include "runtime/init.hpp"
52 #include "runtime/perfData.hpp"
53 #include "runtime/thread.inline.hpp"
54 #include "runtime/threadSMR.hpp"
55 #include "runtime/vmThread.hpp"
56 #include "services/heapDumper.hpp"
57 #include "utilities/align.hpp"
58 #include "utilities/copy.hpp"
59 #include "utilities/events.hpp"
60
61 class ClassLoaderData;
62
63 size_t CollectedHeap::_filler_array_max_size = 0;
64
65 class GCMessage : public FormatBuffer<1024> {
66 public:
67 bool is_before;
68 };
69
70 template <>
71 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
72 st->print_cr("GC heap %s", m.is_before ? "before" : "after");
73 st->print_raw(m);
74 }
75
76 class GCHeapLog : public EventLogBase<GCMessage> {
77 private:
78 void log_heap(CollectedHeap* heap, bool before);
79
80 public:
81 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
82
83 void log_heap_before(CollectedHeap* heap) {
84 log_heap(heap, true);
85 }
86 void log_heap_after(CollectedHeap* heap) {
87 log_heap(heap, false);
88 }
89 };
90
91 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
92 if (!should_log()) {
93 return;
94 }
95
96 double timestamp = fetch_timestamp();
97 MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag);
98 int index = compute_log_index();
99 _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
100 _records[index].timestamp = timestamp;
101 _records[index].data.is_before = before;
102 stringStream st(_records[index].data.buffer(), _records[index].data.size());
103
104 st.print_cr("{Heap %s GC invocations=%u (full %u):",
105 before ? "before" : "after",
106 heap->total_collections(),
107 heap->total_full_collections());
108
109 heap->print_on(&st);
110 st.print_cr("}");
111 }
112
113 size_t CollectedHeap::unused() const {
114 MutexLocker ml(Heap_lock);
115 return capacity() - used();
116 }
117
118 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
119 size_t capacity_in_words = capacity() / HeapWordSize;
120
121 return VirtualSpaceSummary(
122 _reserved.start(), _reserved.start() + capacity_in_words, _reserved.end());
123 }
124
125 GCHeapSummary CollectedHeap::create_heap_summary() {
126 VirtualSpaceSummary heap_space = create_heap_space_summary();
127 return GCHeapSummary(heap_space, used());
128 }
129
130 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
131 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
132 MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
133 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
134 MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
135 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(),
136 MetaspaceUtils::get_combined_statistics(),
137 ms_chunk_free_list_summary, class_chunk_free_list_summary);
138 }
139
140 void CollectedHeap::print_heap_before_gc() {
141 LogTarget(Debug, gc, heap) lt;
142 if (lt.is_enabled()) {
143 LogStream ls(lt);
144 ls.print_cr("Heap before GC invocations=%u (full %u):", total_collections(), total_full_collections());
145 ResourceMark rm;
146 print_on(&ls);
147 }
148
149 if (_gc_heap_log != NULL) {
150 _gc_heap_log->log_heap_before(this);
151 }
152 }
153
154 void CollectedHeap::print_heap_after_gc() {
155 LogTarget(Debug, gc, heap) lt;
156 if (lt.is_enabled()) {
157 LogStream ls(lt);
158 ls.print_cr("Heap after GC invocations=%u (full %u):", total_collections(), total_full_collections());
159 ResourceMark rm;
160 print_on(&ls);
161 }
162
163 if (_gc_heap_log != NULL) {
164 _gc_heap_log->log_heap_after(this);
165 }
166 }
167
168 void CollectedHeap::print() const { print_on(tty); }
169
170 void CollectedHeap::print_on_error(outputStream* st) const {
171 st->print_cr("Heap:");
172 print_extended_on(st);
173 st->cr();
174
175 BarrierSet* bs = BarrierSet::barrier_set();
176 if (bs != NULL) {
177 bs->print_on(st);
178 }
179 }
180
181 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
182 const GCHeapSummary& heap_summary = create_heap_summary();
183 gc_tracer->report_gc_heap_summary(when, heap_summary);
184
185 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
186 gc_tracer->report_metaspace_summary(when, metaspace_summary);
187 }
188
189 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
190 trace_heap(GCWhen::BeforeGC, gc_tracer);
191 }
192
193 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
194 trace_heap(GCWhen::AfterGC, gc_tracer);
195 }
196
197 // Default implementation, for collectors that don't support the feature.
198 bool CollectedHeap::supports_concurrent_gc_breakpoints() const {
199 return false;
200 }
201
202 bool CollectedHeap::is_oop(oop object) const {
203 if (!is_object_aligned(object)) {
204 return false;
205 }
206
207 if (!is_in(object)) {
208 return false;
209 }
210
211 if (is_in(object->klass_or_null())) {
212 return false;
213 }
214
215 return true;
216 }
217
218 // Memory state functions.
219
220
221 CollectedHeap::CollectedHeap() :
222 _capacity_at_last_gc(0),
223 _used_at_last_gc(0),
224 _is_gc_active(false),
225 _last_whole_heap_examined_time_ns(os::javaTimeNanos()),
226 _total_collections(0),
227 _total_full_collections(0),
228 _gc_cause(GCCause::_no_gc),
229 _gc_lastcause(GCCause::_no_gc)
230 {
231 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
232 const size_t elements_per_word = HeapWordSize / sizeof(jint);
233 _filler_array_max_size = align_object_size(filler_array_hdr_size() +
234 max_len / elements_per_word);
235
236 NOT_PRODUCT(_promotion_failure_alot_count = 0;)
237 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
238
239 if (UsePerfData) {
240 EXCEPTION_MARK;
241
242 // create the gc cause jvmstat counters
243 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
244 80, GCCause::to_string(_gc_cause), CHECK);
245
246 _perf_gc_lastcause =
247 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
248 80, GCCause::to_string(_gc_lastcause), CHECK);
249 }
250
251 // Create the ring log
252 if (LogEvents) {
253 _gc_heap_log = new GCHeapLog();
254 } else {
255 _gc_heap_log = NULL;
256 }
257 }
258
259 // This interface assumes that it's being called by the
260 // vm thread. It collects the heap assuming that the
261 // heap lock is already held and that we are executing in
262 // the context of the vm thread.
263 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
264 Thread* thread = Thread::current();
265 assert(thread->is_VM_thread(), "Precondition#1");
266 assert(Heap_lock->is_locked(), "Precondition#2");
267 GCCauseSetter gcs(this, cause);
268 switch (cause) {
269 case GCCause::_heap_inspection:
270 case GCCause::_heap_dump:
271 case GCCause::_metadata_GC_threshold : {
272 HandleMark hm(thread);
273 do_full_collection(false); // don't clear all soft refs
274 break;
275 }
276 case GCCause::_archive_time_gc:
277 case GCCause::_metadata_GC_clear_soft_refs: {
278 HandleMark hm(thread);
279 do_full_collection(true); // do clear all soft refs
280 break;
281 }
282 default:
283 ShouldNotReachHere(); // Unexpected use of this function
284 }
285 }
286
287 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
288 size_t word_size,
289 Metaspace::MetadataType mdtype) {
290 uint loop_count = 0;
291 uint gc_count = 0;
292 uint full_gc_count = 0;
293
294 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
295
296 do {
297 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
298 if (result != NULL) {
299 return result;
300 }
301
302 if (GCLocker::is_active_and_needs_gc()) {
303 // If the GCLocker is active, just expand and allocate.
304 // If that does not succeed, wait if this thread is not
305 // in a critical section itself.
306 result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
307 if (result != NULL) {
308 return result;
309 }
310 JavaThread* jthr = JavaThread::current();
311 if (!jthr->in_critical()) {
312 // Wait for JNI critical section to be exited
313 GCLocker::stall_until_clear();
314 // The GC invoked by the last thread leaving the critical
315 // section will be a young collection and a full collection
316 // is (currently) needed for unloading classes so continue
317 // to the next iteration to get a full GC.
318 continue;
319 } else {
320 if (CheckJNICalls) {
321 fatal("Possible deadlock due to allocating while"
322 " in jni critical section");
323 }
324 return NULL;
325 }
326 }
327
328 { // Need lock to get self consistent gc_count's
329 MutexLocker ml(Heap_lock);
330 gc_count = Universe::heap()->total_collections();
331 full_gc_count = Universe::heap()->total_full_collections();
332 }
333
334 // Generate a VM operation
335 VM_CollectForMetadataAllocation op(loader_data,
336 word_size,
337 mdtype,
338 gc_count,
339 full_gc_count,
340 GCCause::_metadata_GC_threshold);
341 VMThread::execute(&op);
342
343 // If GC was locked out, try again. Check before checking success because the
344 // prologue could have succeeded and the GC still have been locked out.
345 if (op.gc_locked()) {
346 continue;
347 }
348
349 if (op.prologue_succeeded()) {
350 return op.result();
351 }
352 loop_count++;
353 if ((QueuedAllocationWarningCount > 0) &&
354 (loop_count % QueuedAllocationWarningCount == 0)) {
355 log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
356 " size=" SIZE_FORMAT, loop_count, word_size);
357 }
358 } while (true); // Until a GC is done
359 }
360
361 MemoryUsage CollectedHeap::memory_usage() {
362 return MemoryUsage(InitialHeapSize, used(), capacity(), max_capacity());
363 }
364
365 void CollectedHeap::set_gc_cause(GCCause::Cause v) {
366 if (UsePerfData) {
367 _gc_lastcause = _gc_cause;
368 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
369 _perf_gc_cause->set_value(GCCause::to_string(v));
370 }
371 _gc_cause = v;
372 }
373
374 #ifndef PRODUCT
375 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
376 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
377 // please note mismatch between size (in 32/64 bit words), and ju_addr that always point to a 32 bit word
378 for (juint* ju_addr = reinterpret_cast<juint*>(addr); ju_addr < reinterpret_cast<juint*>(addr + size); ++ju_addr) {
379 assert(*ju_addr == badHeapWordVal, "Found non badHeapWordValue in pre-allocation check");
380 }
381 }
382 }
383 #endif // PRODUCT
384
385 size_t CollectedHeap::max_tlab_size() const {
386 // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
387 // This restriction could be removed by enabling filling with multiple arrays.
388 // If we compute that the reasonable way as
389 // header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
390 // we'll overflow on the multiply, so we do the divide first.
391 // We actually lose a little by dividing first,
392 // but that just makes the TLAB somewhat smaller than the biggest array,
393 // which is fine, since we'll be able to fill that.
394 size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
395 sizeof(jint) *
396 ((juint) max_jint / (size_t) HeapWordSize);
397 return align_down(max_int_size, MinObjAlignment);
398 }
399
400 size_t CollectedHeap::filler_array_hdr_size() {
401 return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
402 }
403
404 size_t CollectedHeap::filler_array_min_size() {
405 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
406 }
407
408 #ifdef ASSERT
409 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
410 {
411 assert(words >= min_fill_size(), "too small to fill");
412 assert(is_object_aligned(words), "unaligned size");
413 }
414
415 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
416 {
417 if (ZapFillerObjects && zap) {
418 Copy::fill_to_words(start + filler_array_hdr_size(),
419 words - filler_array_hdr_size(), 0XDEAFBABE);
420 }
421 }
422 #endif // ASSERT
423
424 void
425 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
426 {
427 assert(words >= filler_array_min_size(), "too small for an array");
428 assert(words <= filler_array_max_size(), "too big for a single object");
429
430 const size_t payload_size = words - filler_array_hdr_size();
431 const size_t len = payload_size * HeapWordSize / sizeof(jint);
432 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
433
434 ObjArrayAllocator allocator(Universe::intArrayKlassObj(), words, (int)len, /* do_zero */ false);
435 allocator.initialize(start);
436 DEBUG_ONLY(zap_filler_array(start, words, zap);)
437 }
438
439 void
440 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
441 {
442 assert(words <= filler_array_max_size(), "too big for a single object");
443
444 if (words >= filler_array_min_size()) {
445 fill_with_array(start, words, zap);
446 } else if (words > 0) {
447 assert(words == min_fill_size(), "unaligned size");
448 ObjAllocator allocator(vmClasses::Object_klass(), words);
449 allocator.initialize(start);
450 }
451 }
452
453 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
454 {
455 DEBUG_ONLY(fill_args_check(start, words);)
456 HandleMark hm(Thread::current()); // Free handles before leaving.
457 fill_with_object_impl(start, words, zap);
458 }
459
460 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
461 {
462 DEBUG_ONLY(fill_args_check(start, words);)
463 HandleMark hm(Thread::current()); // Free handles before leaving.
464
465 // Multiple objects may be required depending on the filler array maximum size. Fill
466 // the range up to that with objects that are filler_array_max_size sized. The
467 // remainder is filled with a single object.
468 const size_t min = min_fill_size();
469 const size_t max = filler_array_max_size();
470 while (words > max) {
471 const size_t cur = (words - max) >= min ? max : max - min;
472 fill_with_array(start, cur, zap);
473 start += cur;
474 words -= cur;
475 }
476
477 fill_with_object_impl(start, words, zap);
478 }
479
480 void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
481 CollectedHeap::fill_with_object(start, end, zap);
482 }
483
484 size_t CollectedHeap::min_dummy_object_size() const {
485 return oopDesc::header_size();
486 }
487
488 size_t CollectedHeap::tlab_alloc_reserve() const {
489 size_t min_size = min_dummy_object_size();
490 return min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0;
491 }
492
493 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
494 size_t requested_size,
495 size_t* actual_size) {
496 guarantee(false, "thread-local allocation buffers not supported");
497 return NULL;
498 }
499
500 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
501 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
502 "Should only be called at a safepoint or at start-up");
503
504 ThreadLocalAllocStats stats;
505
506 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next();) {
507 BarrierSet::barrier_set()->make_parsable(thread);
508 if (UseTLAB) {
509 if (retire_tlabs) {
510 thread->tlab().retire(&stats);
511 } else {
512 thread->tlab().make_parsable();
513 }
514 }
515 }
516
517 stats.publish();
518 }
519
520 void CollectedHeap::resize_all_tlabs() {
521 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
522 "Should only resize tlabs at safepoint");
523
524 if (UseTLAB && ResizeTLAB) {
525 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
526 thread->tlab().resize();
527 }
528 }
529 }
530
531 jlong CollectedHeap::millis_since_last_whole_heap_examined() {
532 return (os::javaTimeNanos() - _last_whole_heap_examined_time_ns) / NANOSECS_PER_MILLISEC;
533 }
534
535 void CollectedHeap::record_whole_heap_examined_timestamp() {
536 _last_whole_heap_examined_time_ns = os::javaTimeNanos();
537 }
538
539 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
540 assert(timer != NULL, "timer is null");
541 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
542 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
543 HeapDumper::dump_heap();
544 }
545
546 LogTarget(Trace, gc, classhisto) lt;
547 if (lt.is_enabled()) {
548 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
549 ResourceMark rm;
550 LogStream ls(lt);
551 VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
552 inspector.doit();
553 }
554 }
555
556 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
557 full_gc_dump(timer, true);
558 }
559
560 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
561 full_gc_dump(timer, false);
562 }
563
564 void CollectedHeap::initialize_reserved_region(const ReservedHeapSpace& rs) {
565 // It is important to do this in a way such that concurrent readers can't
566 // temporarily think something is in the heap. (Seen this happen in asserts.)
567 _reserved.set_word_size(0);
568 _reserved.set_start((HeapWord*)rs.base());
569 _reserved.set_end((HeapWord*)rs.end());
570 }
571
572 void CollectedHeap::post_initialize() {
573 StringDedup::initialize();
574 initialize_serviceability();
575 }
576
577 #ifndef PRODUCT
578
579 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
580 // Access to count is not atomic; the value does not have to be exact.
581 if (PromotionFailureALot) {
582 const size_t gc_num = total_collections();
583 const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
584 if (elapsed_gcs >= PromotionFailureALotInterval) {
585 // Test for unsigned arithmetic wrap-around.
586 if (++*count >= PromotionFailureALotCount) {
587 *count = 0;
588 return true;
589 }
590 }
591 }
592 return false;
593 }
594
595 bool CollectedHeap::promotion_should_fail() {
596 return promotion_should_fail(&_promotion_failure_alot_count);
597 }
598
599 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
600 if (PromotionFailureALot) {
601 _promotion_failure_alot_gc_number = total_collections();
602 *count = 0;
603 }
604 }
605
606 void CollectedHeap::reset_promotion_should_fail() {
607 reset_promotion_should_fail(&_promotion_failure_alot_count);
608 }
609
610 #endif // #ifndef PRODUCT
611
612 bool CollectedHeap::supports_object_pinning() const {
613 return false;
614 }
615
616 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) {
617 ShouldNotReachHere();
618 return NULL;
619 }
620
621 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
622 ShouldNotReachHere();
623 }
624
625 bool CollectedHeap::is_archived_object(oop object) const {
626 return false;
627 }
628
629 uint32_t CollectedHeap::hash_oop(oop obj) const {
630 const uintptr_t addr = cast_from_oop<uintptr_t>(obj);
631 return static_cast<uint32_t>(addr >> LogMinObjAlignment);
632 }
633
634 // It's the caller's responsibility to ensure glitch-freedom
635 // (if required).
636 void CollectedHeap::update_capacity_and_used_at_gc() {
637 _capacity_at_last_gc = capacity();
638 _used_at_last_gc = used();
639 }