1 /*
2 * Copyright (c) 2001, 2019, 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/mutexLocker.inline.hpp"
47 #include "runtime/thread.inline.hpp"
48 #include "runtime/threadSMR.hpp"
49 #include "runtime/vmThread.hpp"
50 #include "services/heapDumper.hpp"
51 #include "utilities/align.hpp"
52 #include "utilities/copy.hpp"
53 #include "utilities/events.inline.hpp"
54
55 class ClassLoaderData;
56
57 size_t CollectedHeap::_filler_array_max_size = 0;
58
59 class GCHeapLog : public EventLogBase<GCMessage> {
60 private:
61 void log_heap(CollectedHeap* heap, bool before);
62
63 public:
64 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
65
66 void log_heap_before(CollectedHeap* heap) {
67 log_heap(heap, true);
68 }
69 void log_heap_after(CollectedHeap* heap) {
70 log_heap(heap, false);
71 }
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 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
81 if (!should_log()) {
82 return;
83 }
84
85 double timestamp = fetch_timestamp();
86 MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag);
87 int index = compute_log_index();
88 _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
89 _records[index].timestamp = timestamp;
90 _records[index].data.is_before = before;
91 stringStream st(_records[index].data.buffer(), _records[index].data.size());
92
93 st.print_cr("{Heap %s GC invocations=%u (full %u):",
94 before ? "before" : "after",
95 heap->total_collections(),
96 heap->total_full_collections());
97
98 heap->print_on(&st);
99 st.print_cr("}");
100 }
101
102 size_t CollectedHeap::unused() const {
103 MutexLocker ml(Heap_lock);
104 return capacity() - used();
105 }
106
107 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
108 size_t capacity_in_words = capacity() / HeapWordSize;
109
110 return VirtualSpaceSummary(
111 _reserved.start(), _reserved.start() + capacity_in_words, _reserved.end());
112 }
113
114 GCHeapSummary CollectedHeap::create_heap_summary() {
115 VirtualSpaceSummary heap_space = create_heap_space_summary();
116 return GCHeapSummary(heap_space, used());
117 }
118
119 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
120 const MetaspaceSizes meta_space(
121 MetaspaceUtils::committed_bytes(),
122 MetaspaceUtils::used_bytes(),
123 MetaspaceUtils::reserved_bytes());
124 const MetaspaceSizes data_space(
125 MetaspaceUtils::committed_bytes(Metaspace::NonClassType),
126 MetaspaceUtils::used_bytes(Metaspace::NonClassType),
127 MetaspaceUtils::reserved_bytes(Metaspace::NonClassType));
128 const MetaspaceSizes class_space(
129 MetaspaceUtils::committed_bytes(Metaspace::ClassType),
130 MetaspaceUtils::used_bytes(Metaspace::ClassType),
131 MetaspaceUtils::reserved_bytes(Metaspace::ClassType));
132
133 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
134 MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
135 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
136 MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
137
138 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
139 ms_chunk_free_list_summary, class_chunk_free_list_summary);
140 }
141
142 void CollectedHeap::print_heap_before_gc() {
143 Universe::print_heap_before_gc();
144 if (_gc_heap_log != NULL) {
145 _gc_heap_log->log_heap_before(this);
146 }
147 }
148
149 void CollectedHeap::print_heap_after_gc() {
150 Universe::print_heap_after_gc();
151 if (_gc_heap_log != NULL) {
152 _gc_heap_log->log_heap_after(this);
153 }
154 }
155
156 void CollectedHeap::print() const { print_on(tty); }
157
158 void CollectedHeap::print_on_error(outputStream* st) const {
159 st->print_cr("Heap:");
160 print_extended_on(st);
161 st->cr();
162
163 BarrierSet::barrier_set()->print_on(st);
164 }
165
166 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
167 const GCHeapSummary& heap_summary = create_heap_summary();
168 gc_tracer->report_gc_heap_summary(when, heap_summary);
169
170 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
171 gc_tracer->report_metaspace_summary(when, metaspace_summary);
172 }
173
174 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
175 trace_heap(GCWhen::BeforeGC, gc_tracer);
176 }
177
178 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
179 trace_heap(GCWhen::AfterGC, gc_tracer);
180 }
181
182 // WhiteBox API support for concurrent collectors. These are the
183 // default implementations, for collectors which don't support this
184 // feature.
185 bool CollectedHeap::supports_concurrent_phase_control() const {
186 return false;
187 }
188
189 bool CollectedHeap::request_concurrent_phase(const char* phase) {
190 return false;
191 }
192
193 bool CollectedHeap::is_oop(oop object) const {
194 if (!is_object_aligned(object)) {
195 return false;
196 }
197
198 if (!is_in(object)) {
199 return false;
200 }
201
202 if (is_in(object->klass_or_null())) {
203 return false;
204 }
205
206 return true;
207 }
208
209 // Memory state functions.
210
211
212 CollectedHeap::CollectedHeap() :
213 _is_gc_active(false),
214 _total_collections(0),
215 _total_full_collections(0),
216 _gc_cause(GCCause::_no_gc),
217 _gc_lastcause(GCCause::_no_gc)
218 {
219 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
220 const size_t elements_per_word = HeapWordSize / sizeof(jint);
221 _filler_array_max_size = align_object_size(filler_array_hdr_size() +
222 max_len / elements_per_word);
223
224 NOT_PRODUCT(_promotion_failure_alot_count = 0;)
225 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
226
227 if (UsePerfData) {
228 EXCEPTION_MARK;
229
230 // create the gc cause jvmstat counters
231 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
232 80, GCCause::to_string(_gc_cause), CHECK);
233
234 _perf_gc_lastcause =
235 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
236 80, GCCause::to_string(_gc_lastcause), CHECK);
237 }
238
239 // Create the ring log
240 if (LogEvents) {
241 _gc_heap_log = new GCHeapLog();
242 } else {
243 _gc_heap_log = NULL;
244 }
245 }
246
247 // This interface assumes that it's being called by the
248 // vm thread. It collects the heap assuming that the
249 // heap lock is already held and that we are executing in
250 // the context of the vm thread.
251 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
252 assert(Thread::current()->is_VM_thread(), "Precondition#1");
253 assert(Heap_lock->is_locked(), "Precondition#2");
254 GCCauseSetter gcs(this, cause);
255 switch (cause) {
256 case GCCause::_heap_inspection:
257 case GCCause::_heap_dump:
258 case GCCause::_metadata_GC_threshold : {
259 HandleMark hm;
260 do_full_collection(false); // don't clear all soft refs
261 break;
262 }
263 case GCCause::_metadata_GC_clear_soft_refs: {
264 HandleMark hm;
265 do_full_collection(true); // do clear all soft refs
266 break;
267 }
268 default:
269 ShouldNotReachHere(); // Unexpected use of this function
270 }
271 }
272
273 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
274 size_t word_size,
275 Metaspace::MetadataType mdtype) {
276 uint loop_count = 0;
277 uint gc_count = 0;
278 uint full_gc_count = 0;
279
280 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
281
282 do {
283 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
284 if (result != NULL) {
285 return result;
286 }
287
288 if (GCLocker::is_active_and_needs_gc()) {
289 // If the GCLocker is active, just expand and allocate.
290 // If that does not succeed, wait if this thread is not
291 // in a critical section itself.
292 result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
293 if (result != NULL) {
294 return result;
295 }
296 JavaThread* jthr = JavaThread::current();
297 if (!jthr->in_critical()) {
298 // Wait for JNI critical section to be exited
299 GCLocker::stall_until_clear();
300 // The GC invoked by the last thread leaving the critical
301 // section will be a young collection and a full collection
302 // is (currently) needed for unloading classes so continue
303 // to the next iteration to get a full GC.
304 continue;
305 } else {
306 if (CheckJNICalls) {
307 fatal("Possible deadlock due to allocating while"
308 " in jni critical section");
309 }
310 return NULL;
311 }
312 }
313
314 { // Need lock to get self consistent gc_count's
315 MutexLocker ml(Heap_lock);
316 gc_count = Universe::heap()->total_collections();
317 full_gc_count = Universe::heap()->total_full_collections();
318 }
319
320 // Generate a VM operation
321 VM_CollectForMetadataAllocation op(loader_data,
322 word_size,
323 mdtype,
324 gc_count,
325 full_gc_count,
326 GCCause::_metadata_GC_threshold);
327 VMThread::execute(&op);
328
329 // If GC was locked out, try again. Check before checking success because the
330 // prologue could have succeeded and the GC still have been locked out.
331 if (op.gc_locked()) {
332 continue;
333 }
334
335 if (op.prologue_succeeded()) {
336 return op.result();
337 }
338 loop_count++;
339 if ((QueuedAllocationWarningCount > 0) &&
340 (loop_count % QueuedAllocationWarningCount == 0)) {
341 log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
342 " size=" SIZE_FORMAT, loop_count, word_size);
343 }
344 } while (true); // Until a GC is done
345 }
346
347 MemoryUsage CollectedHeap::memory_usage() {
348 return MemoryUsage(InitialHeapSize, used(), capacity(), max_capacity());
349 }
350
351
352 #ifndef PRODUCT
353 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
354 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
355 for (size_t slot = 0; slot < size; slot += 1) {
356 assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
357 "Found non badHeapWordValue in pre-allocation check");
358 }
359 }
360 }
361 #endif // PRODUCT
362
363 size_t CollectedHeap::max_tlab_size() const {
364 // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
365 // This restriction could be removed by enabling filling with multiple arrays.
366 // If we compute that the reasonable way as
367 // header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
368 // we'll overflow on the multiply, so we do the divide first.
369 // We actually lose a little by dividing first,
370 // but that just makes the TLAB somewhat smaller than the biggest array,
371 // which is fine, since we'll be able to fill that.
372 size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
373 sizeof(jint) *
374 ((juint) max_jint / (size_t) HeapWordSize);
375 return align_down(max_int_size, MinObjAlignment);
376 }
377
378 size_t CollectedHeap::filler_array_hdr_size() {
379 return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
380 }
381
382 size_t CollectedHeap::filler_array_min_size() {
383 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
384 }
385
386 #ifdef ASSERT
387 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
388 {
389 assert(words >= min_fill_size(), "too small to fill");
390 assert(is_object_aligned(words), "unaligned size");
391 }
392
393 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
394 {
395 if (ZapFillerObjects && zap) {
396 Copy::fill_to_words(start + filler_array_hdr_size(),
397 words - filler_array_hdr_size(), 0XDEAFBABE);
398 }
399 }
400 #endif // ASSERT
401
402 void
403 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
404 {
405 assert(words >= filler_array_min_size(), "too small for an array");
406 assert(words <= filler_array_max_size(), "too big for a single object");
407
408 const size_t payload_size = words - filler_array_hdr_size();
409 const size_t len = payload_size * HeapWordSize / sizeof(jint);
410 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
411
412 ObjArrayAllocator allocator(Universe::intArrayKlassObj(), words, (int)len, /* do_zero */ false);
413 allocator.initialize(start);
414 DEBUG_ONLY(zap_filler_array(start, words, zap);)
415 }
416
417 void
418 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
419 {
420 assert(words <= filler_array_max_size(), "too big for a single object");
421
422 if (words >= filler_array_min_size()) {
423 fill_with_array(start, words, zap);
424 } else if (words > 0) {
425 assert(words == min_fill_size(), "unaligned size");
426 ObjAllocator allocator(SystemDictionary::Object_klass(), words);
427 allocator.initialize(start);
428 }
429 }
430
431 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
432 {
433 DEBUG_ONLY(fill_args_check(start, words);)
434 HandleMark hm; // Free handles before leaving.
435 fill_with_object_impl(start, words, zap);
436 }
437
438 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
439 {
440 DEBUG_ONLY(fill_args_check(start, words);)
441 HandleMark hm; // Free handles before leaving.
442
443 // Multiple objects may be required depending on the filler array maximum size. Fill
444 // the range up to that with objects that are filler_array_max_size sized. The
445 // remainder is filled with a single object.
446 const size_t min = min_fill_size();
447 const size_t max = filler_array_max_size();
448 while (words > max) {
449 const size_t cur = (words - max) >= min ? max : max - min;
450 fill_with_array(start, cur, zap);
451 start += cur;
452 words -= cur;
453 }
454
455 fill_with_object_impl(start, words, zap);
456 }
457
458 void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
459 CollectedHeap::fill_with_object(start, end, zap);
460 }
461
462 size_t CollectedHeap::min_dummy_object_size() const {
463 return oopDesc::header_size();
464 }
465
466 size_t CollectedHeap::tlab_alloc_reserve() const {
467 size_t min_size = min_dummy_object_size();
468 return min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0;
469 }
470
471 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
472 size_t requested_size,
473 size_t* actual_size) {
474 guarantee(false, "thread-local allocation buffers not supported");
475 return NULL;
476 }
477
478 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
479 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
480 "Should only be called at a safepoint or at start-up");
481
482 ThreadLocalAllocStats stats;
483
484 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next();) {
485 BarrierSet::barrier_set()->make_parsable(thread);
486 if (UseTLAB) {
487 if (retire_tlabs) {
488 thread->tlab().retire(&stats);
489 } else {
490 thread->tlab().make_parsable();
491 }
492 }
493 }
494
495 stats.publish();
496 }
497
498 void CollectedHeap::resize_all_tlabs() {
499 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
500 "Should only resize tlabs at safepoint");
501
502 if (UseTLAB && ResizeTLAB) {
503 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
504 thread->tlab().resize();
505 }
506 }
507 }
508
509 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
510 assert(timer != NULL, "timer is null");
511 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
512 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
513 HeapDumper::dump_heap();
514 }
515
516 LogTarget(Trace, gc, classhisto) lt;
517 if (lt.is_enabled()) {
518 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
519 ResourceMark rm;
520 LogStream ls(lt);
521 VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
522 inspector.doit();
523 }
524 }
525
526 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
527 full_gc_dump(timer, true);
528 }
529
530 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
531 full_gc_dump(timer, false);
532 }
533
534 void CollectedHeap::initialize_reserved_region(const ReservedHeapSpace& rs) {
535 // It is important to do this in a way such that concurrent readers can't
536 // temporarily think something is in the heap. (Seen this happen in asserts.)
537 _reserved.set_word_size(0);
538 _reserved.set_start((HeapWord*)rs.base());
539 _reserved.set_end((HeapWord*)rs.end());
540 }
541
542 void CollectedHeap::post_initialize() {
543 initialize_serviceability();
544 }
545
546 #ifndef PRODUCT
547
548 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
549 // Access to count is not atomic; the value does not have to be exact.
550 if (PromotionFailureALot) {
551 const size_t gc_num = total_collections();
552 const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
553 if (elapsed_gcs >= PromotionFailureALotInterval) {
554 // Test for unsigned arithmetic wrap-around.
555 if (++*count >= PromotionFailureALotCount) {
556 *count = 0;
557 return true;
558 }
559 }
560 }
561 return false;
562 }
563
564 bool CollectedHeap::promotion_should_fail() {
565 return promotion_should_fail(&_promotion_failure_alot_count);
566 }
567
568 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
569 if (PromotionFailureALot) {
570 _promotion_failure_alot_gc_number = total_collections();
571 *count = 0;
572 }
573 }
574
575 void CollectedHeap::reset_promotion_should_fail() {
576 reset_promotion_should_fail(&_promotion_failure_alot_count);
577 }
578
579 #endif // #ifndef PRODUCT
580
581 bool CollectedHeap::supports_object_pinning() const {
582 return false;
583 }
584
585 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) {
586 ShouldNotReachHere();
587 return NULL;
588 }
589
590 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
591 ShouldNotReachHere();
592 }
593
594 void CollectedHeap::deduplicate_string(oop str) {
595 // Do nothing, unless overridden in subclass.
596 }
597
598 size_t CollectedHeap::obj_size(oop obj) const {
599 return obj->size();
600 }
601
602 uint32_t CollectedHeap::hash_oop(oop obj) const {
603 const uintptr_t addr = cast_from_oop<uintptr_t>(obj);
604 return static_cast<uint32_t>(addr >> LogMinObjAlignment);
605 }