1 /*
2 * Copyright (c) 2001, 2020, 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/systemDictionary.hpp"
27 #include "gc/shared/allocTracer.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/collectedHeap.hpp"
30 #include "gc/shared/collectedHeap.inline.hpp"
31 #include "gc/shared/gcLocker.inline.hpp"
32 #include "gc/shared/gcHeapSummary.hpp"
33 #include "gc/shared/gcTrace.hpp"
34 #include "gc/shared/gcTraceTime.inline.hpp"
35 #include "gc/shared/gcVMOperations.hpp"
36 #include "gc/shared/gcWhen.hpp"
37 #include "gc/shared/memAllocator.hpp"
38 #include "logging/log.hpp"
39 #include "memory/metaspace.hpp"
40 #include "memory/resourceArea.hpp"
41 #include "memory/universe.hpp"
42 #include "oops/instanceMirrorKlass.hpp"
43 #include "oops/oop.inline.hpp"
44 #include "runtime/handles.inline.hpp"
45 #include "runtime/init.hpp"
46 #include "runtime/thread.inline.hpp"
47 #include "runtime/threadSMR.hpp"
48 #include "runtime/vmThread.hpp"
49 #include "services/heapDumper.hpp"
50 #include "utilities/align.hpp"
51 #include "utilities/copy.hpp"
52
53 class ClassLoaderData;
54
55 size_t CollectedHeap::_filler_array_max_size = 0;
56
57 template <>
58 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
59 st->print_cr("GC heap %s", m.is_before ? "before" : "after");
60 st->print_raw(m);
61 }
62
63 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
64 if (!should_log()) {
65 return;
66 }
67
68 double timestamp = fetch_timestamp();
69 MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag);
70 int index = compute_log_index();
71 _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
72 _records[index].timestamp = timestamp;
73 _records[index].data.is_before = before;
74 stringStream st(_records[index].data.buffer(), _records[index].data.size());
75
76 st.print_cr("{Heap %s GC invocations=%u (full %u):",
77 before ? "before" : "after",
78 heap->total_collections(),
79 heap->total_full_collections());
80
81 heap->print_on(&st);
82 st.print_cr("}");
83 }
84
85 size_t CollectedHeap::unused() const {
86 MutexLocker ml(Heap_lock);
87 return capacity() - used();
88 }
89
90 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
91 size_t capacity_in_words = capacity() / HeapWordSize;
92
93 return VirtualSpaceSummary(
94 _reserved.start(), _reserved.start() + capacity_in_words, _reserved.end());
95 }
96
97 GCHeapSummary CollectedHeap::create_heap_summary() {
98 VirtualSpaceSummary heap_space = create_heap_space_summary();
99 return GCHeapSummary(heap_space, used());
100 }
101
102 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
103 const MetaspaceSizes meta_space(
104 MetaspaceUtils::committed_bytes(),
105 MetaspaceUtils::used_bytes(),
106 MetaspaceUtils::reserved_bytes());
107 const MetaspaceSizes data_space(
108 MetaspaceUtils::committed_bytes(Metaspace::NonClassType),
109 MetaspaceUtils::used_bytes(Metaspace::NonClassType),
110 MetaspaceUtils::reserved_bytes(Metaspace::NonClassType));
111 const MetaspaceSizes class_space(
112 MetaspaceUtils::committed_bytes(Metaspace::ClassType),
113 MetaspaceUtils::used_bytes(Metaspace::ClassType),
114 MetaspaceUtils::reserved_bytes(Metaspace::ClassType));
115
116 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
117 MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
118 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
119 MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
120
121 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
122 ms_chunk_free_list_summary, class_chunk_free_list_summary);
123 }
124
125 void CollectedHeap::run_task_at_safepoint(AbstractGangTask* task, uint num_workers) {
126 WorkGang* gang = safepoint_workers();
127 if (gang == NULL) {
128 // GC doesn't support parallel worker threads.
129 // Execute in this thread with worker id 0.
130 task->work(0);
131 } else {
132 gang->run_task(task, num_workers);
133 }
134 }
135
136 void CollectedHeap::print_heap_before_gc() {
137 Universe::print_heap_before_gc();
138 if (_gc_heap_log != NULL) {
139 _gc_heap_log->log_heap_before(this);
140 }
141 }
142
143 void CollectedHeap::print_heap_after_gc() {
144 Universe::print_heap_after_gc();
145 if (_gc_heap_log != NULL) {
146 _gc_heap_log->log_heap_after(this);
147 }
148 }
149
150 void CollectedHeap::print() const { print_on(tty); }
151
152 void CollectedHeap::print_on_error(outputStream* st) const {
153 st->print_cr("Heap:");
154 print_extended_on(st);
155 st->cr();
156
157 BarrierSet* bs = BarrierSet::barrier_set();
158 if (bs != NULL) {
159 bs->print_on(st);
160 }
161 }
162
163 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
164 const GCHeapSummary& heap_summary = create_heap_summary();
165 gc_tracer->report_gc_heap_summary(when, heap_summary);
166
167 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
168 gc_tracer->report_metaspace_summary(when, metaspace_summary);
169 }
170
171 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
172 trace_heap(GCWhen::BeforeGC, gc_tracer);
173 }
174
175 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
176 trace_heap(GCWhen::AfterGC, gc_tracer);
177 }
178
179 // Default implementation, for collectors that don't support the feature.
180 bool CollectedHeap::supports_concurrent_gc_breakpoints() const {
181 return false;
182 }
183
184 bool CollectedHeap::is_oop(oop object) const {
185 if (!is_object_aligned(object)) {
186 return false;
187 }
188
189 if (!is_in(object)) {
190 return false;
191 }
192
193 if (is_in(object->klass_or_null())) {
194 return false;
195 }
196
197 return true;
198 }
199
200 // Memory state functions.
201
202
203 CollectedHeap::CollectedHeap() :
204 _is_gc_active(false),
205 _last_whole_heap_examined_time_ns(os::javaTimeNanos()),
206 _total_collections(0),
207 _total_full_collections(0),
208 _gc_cause(GCCause::_no_gc),
209 _gc_lastcause(GCCause::_no_gc)
210 {
211 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
212 const size_t elements_per_word = HeapWordSize / sizeof(jint);
213 _filler_array_max_size = align_object_size(filler_array_hdr_size() +
214 max_len / elements_per_word);
215
216 NOT_PRODUCT(_promotion_failure_alot_count = 0;)
217 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
218
219 if (UsePerfData) {
220 EXCEPTION_MARK;
221
222 // create the gc cause jvmstat counters
223 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
224 80, GCCause::to_string(_gc_cause), CHECK);
225
226 _perf_gc_lastcause =
227 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
228 80, GCCause::to_string(_gc_lastcause), CHECK);
229 }
230
231 // Create the ring log
232 if (LogEvents) {
233 _gc_heap_log = new GCHeapLog();
234 } else {
235 _gc_heap_log = NULL;
236 }
237 }
238
239 // This interface assumes that it's being called by the
240 // vm thread. It collects the heap assuming that the
241 // heap lock is already held and that we are executing in
242 // the context of the vm thread.
243 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
244 Thread* thread = Thread::current();
245 assert(thread->is_VM_thread(), "Precondition#1");
246 assert(Heap_lock->is_locked(), "Precondition#2");
247 GCCauseSetter gcs(this, cause);
248 switch (cause) {
249 case GCCause::_heap_inspection:
250 case GCCause::_heap_dump:
251 case GCCause::_metadata_GC_threshold : {
252 HandleMark hm(thread);
253 do_full_collection(false); // don't clear all soft refs
254 break;
255 }
256 case GCCause::_archive_time_gc:
257 case GCCause::_metadata_GC_clear_soft_refs: {
258 HandleMark hm(thread);
259 do_full_collection(true); // do clear all soft refs
260 break;
261 }
262 default:
263 ShouldNotReachHere(); // Unexpected use of this function
264 }
265 }
266
267 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
268 size_t word_size,
269 Metaspace::MetadataType mdtype) {
270 uint loop_count = 0;
271 uint gc_count = 0;
272 uint full_gc_count = 0;
273
274 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
275
276 do {
277 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
278 if (result != NULL) {
279 return result;
280 }
281
282 if (GCLocker::is_active_and_needs_gc()) {
283 // If the GCLocker is active, just expand and allocate.
284 // If that does not succeed, wait if this thread is not
285 // in a critical section itself.
286 result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
287 if (result != NULL) {
288 return result;
289 }
290 JavaThread* jthr = JavaThread::current();
291 if (!jthr->in_critical()) {
292 // Wait for JNI critical section to be exited
293 GCLocker::stall_until_clear();
294 // The GC invoked by the last thread leaving the critical
295 // section will be a young collection and a full collection
296 // is (currently) needed for unloading classes so continue
297 // to the next iteration to get a full GC.
298 continue;
299 } else {
300 if (CheckJNICalls) {
301 fatal("Possible deadlock due to allocating while"
302 " in jni critical section");
303 }
304 return NULL;
305 }
306 }
307
308 { // Need lock to get self consistent gc_count's
309 MutexLocker ml(Heap_lock);
310 gc_count = Universe::heap()->total_collections();
311 full_gc_count = Universe::heap()->total_full_collections();
312 }
313
314 // Generate a VM operation
315 VM_CollectForMetadataAllocation op(loader_data,
316 word_size,
317 mdtype,
318 gc_count,
319 full_gc_count,
320 GCCause::_metadata_GC_threshold);
321 VMThread::execute(&op);
322
323 // If GC was locked out, try again. Check before checking success because the
324 // prologue could have succeeded and the GC still have been locked out.
325 if (op.gc_locked()) {
326 continue;
327 }
328
329 if (op.prologue_succeeded()) {
330 return op.result();
331 }
332 loop_count++;
333 if ((QueuedAllocationWarningCount > 0) &&
334 (loop_count % QueuedAllocationWarningCount == 0)) {
335 log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
336 " size=" SIZE_FORMAT, loop_count, word_size);
337 }
338 } while (true); // Until a GC is done
339 }
340
341 MemoryUsage CollectedHeap::memory_usage() {
342 return MemoryUsage(InitialHeapSize, used(), capacity(), max_capacity());
343 }
344
345
346 #ifndef PRODUCT
347 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
348 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
349 // please note mismatch between size (in 32/64 bit words), and ju_addr that always point to a 32 bit word
350 for (juint* ju_addr = reinterpret_cast<juint*>(addr); ju_addr < reinterpret_cast<juint*>(addr + size); ++ju_addr) {
351 assert(*ju_addr == badHeapWordVal, "Found non badHeapWordValue in pre-allocation check");
352 }
353 }
354 }
355 #endif // PRODUCT
356
357 size_t CollectedHeap::max_tlab_size() const {
358 // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
359 // This restriction could be removed by enabling filling with multiple arrays.
360 // If we compute that the reasonable way as
361 // header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
362 // we'll overflow on the multiply, so we do the divide first.
363 // We actually lose a little by dividing first,
364 // but that just makes the TLAB somewhat smaller than the biggest array,
365 // which is fine, since we'll be able to fill that.
366 size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
367 sizeof(jint) *
368 ((juint) max_jint / (size_t) HeapWordSize);
369 return align_down(max_int_size, MinObjAlignment);
370 }
371
372 size_t CollectedHeap::filler_array_hdr_size() {
373 return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
374 }
375
376 size_t CollectedHeap::filler_array_min_size() {
377 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
378 }
379
380 #ifdef ASSERT
381 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
382 {
383 assert(words >= min_fill_size(), "too small to fill");
384 assert(is_object_aligned(words), "unaligned size");
385 }
386
387 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
388 {
389 if (ZapFillerObjects && zap) {
390 Copy::fill_to_words(start + filler_array_hdr_size(),
391 words - filler_array_hdr_size(), 0XDEAFBABE);
392 }
393 }
394 #endif // ASSERT
395
396 void
397 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
398 {
399 assert(words >= filler_array_min_size(), "too small for an array");
400 assert(words <= filler_array_max_size(), "too big for a single object");
401
402 const size_t payload_size = words - filler_array_hdr_size();
403 const size_t len = payload_size * HeapWordSize / sizeof(jint);
404 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
405
406 ObjArrayAllocator allocator(Universe::intArrayKlassObj(), words, (int)len, /* do_zero */ false);
407 allocator.initialize(start);
408 DEBUG_ONLY(zap_filler_array(start, words, zap);)
409 }
410
411 void
412 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
413 {
414 assert(words <= filler_array_max_size(), "too big for a single object");
415
416 if (words >= filler_array_min_size()) {
417 fill_with_array(start, words, zap);
418 } else if (words > 0) {
419 assert(words == min_fill_size(), "unaligned size");
420 ObjAllocator allocator(SystemDictionary::Object_klass(), words);
421 allocator.initialize(start);
422 }
423 }
424
425 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
426 {
427 DEBUG_ONLY(fill_args_check(start, words);)
428 HandleMark hm(Thread::current()); // Free handles before leaving.
429 fill_with_object_impl(start, words, zap);
430 }
431
432 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
433 {
434 DEBUG_ONLY(fill_args_check(start, words);)
435 HandleMark hm(Thread::current()); // Free handles before leaving.
436
437 // Multiple objects may be required depending on the filler array maximum size. Fill
438 // the range up to that with objects that are filler_array_max_size sized. The
439 // remainder is filled with a single object.
440 const size_t min = min_fill_size();
441 const size_t max = filler_array_max_size();
442 while (words > max) {
443 const size_t cur = (words - max) >= min ? max : max - min;
444 fill_with_array(start, cur, zap);
445 start += cur;
446 words -= cur;
447 }
448
449 fill_with_object_impl(start, words, zap);
450 }
451
452 void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
453 CollectedHeap::fill_with_object(start, end, zap);
454 }
455
456 size_t CollectedHeap::min_dummy_object_size() const {
457 return oopDesc::header_size();
458 }
459
460 size_t CollectedHeap::tlab_alloc_reserve() const {
461 size_t min_size = min_dummy_object_size();
462 return min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0;
463 }
464
465 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
466 size_t requested_size,
467 size_t* actual_size) {
468 guarantee(false, "thread-local allocation buffers not supported");
469 return NULL;
470 }
471
472 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
473 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
474 "Should only be called at a safepoint or at start-up");
475
476 ThreadLocalAllocStats stats;
477
478 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next();) {
479 BarrierSet::barrier_set()->make_parsable(thread);
480 if (UseTLAB) {
481 if (retire_tlabs) {
482 thread->tlab().retire(&stats);
483 } else {
484 thread->tlab().make_parsable();
485 }
486 }
487 }
488
489 stats.publish();
490 }
491
492 void CollectedHeap::resize_all_tlabs() {
493 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
494 "Should only resize tlabs at safepoint");
495
496 if (UseTLAB && ResizeTLAB) {
497 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
498 thread->tlab().resize();
499 }
500 }
501 }
502
503 jlong CollectedHeap::millis_since_last_whole_heap_examined() {
504 return (os::javaTimeNanos() - _last_whole_heap_examined_time_ns) / NANOSECS_PER_MILLISEC;
505 }
506
507 void CollectedHeap::record_whole_heap_examined_timestamp() {
508 _last_whole_heap_examined_time_ns = os::javaTimeNanos();
509 }
510
511 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
512 assert(timer != NULL, "timer is null");
513 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
514 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
515 HeapDumper::dump_heap();
516 }
517
518 LogTarget(Trace, gc, classhisto) lt;
519 if (lt.is_enabled()) {
520 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
521 ResourceMark rm;
522 LogStream ls(lt);
523 VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
524 inspector.doit();
525 }
526 }
527
528 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
529 full_gc_dump(timer, true);
530 }
531
532 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
533 full_gc_dump(timer, false);
534 }
535
536 void CollectedHeap::initialize_reserved_region(const ReservedHeapSpace& rs) {
537 // It is important to do this in a way such that concurrent readers can't
538 // temporarily think something is in the heap. (Seen this happen in asserts.)
539 _reserved.set_word_size(0);
540 _reserved.set_start((HeapWord*)rs.base());
541 _reserved.set_end((HeapWord*)rs.end());
542 }
543
544 void CollectedHeap::post_initialize() {
545 initialize_serviceability();
546 }
547
548 #ifndef PRODUCT
549
550 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
551 // Access to count is not atomic; the value does not have to be exact.
552 if (PromotionFailureALot) {
553 const size_t gc_num = total_collections();
554 const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
555 if (elapsed_gcs >= PromotionFailureALotInterval) {
556 // Test for unsigned arithmetic wrap-around.
557 if (++*count >= PromotionFailureALotCount) {
558 *count = 0;
559 return true;
560 }
561 }
562 }
563 return false;
564 }
565
566 bool CollectedHeap::promotion_should_fail() {
567 return promotion_should_fail(&_promotion_failure_alot_count);
568 }
569
570 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
571 if (PromotionFailureALot) {
572 _promotion_failure_alot_gc_number = total_collections();
573 *count = 0;
574 }
575 }
576
577 void CollectedHeap::reset_promotion_should_fail() {
578 reset_promotion_should_fail(&_promotion_failure_alot_count);
579 }
580
581 #endif // #ifndef PRODUCT
582
583 bool CollectedHeap::supports_object_pinning() const {
584 return false;
585 }
586
587 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) {
588 ShouldNotReachHere();
589 return NULL;
590 }
591
592 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
593 ShouldNotReachHere();
594 }
595
596 void CollectedHeap::deduplicate_string(oop str) {
597 // Do nothing, unless overridden in subclass.
598 }
599
600 uint32_t CollectedHeap::hash_oop(oop obj) const {
601 const uintptr_t addr = cast_from_oop<uintptr_t>(obj);
602 return static_cast<uint32_t>(addr >> LogMinObjAlignment);
603 }