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