1 /*
2 * Copyright (c) 2001, 2017, 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.inline.hpp"
29 #include "gc/shared/collectedHeap.hpp"
30 #include "gc/shared/collectedHeap.inline.hpp"
31 #include "gc/shared/gcHeapSummary.hpp"
32 #include "gc/shared/gcTrace.hpp"
33 #include "gc/shared/gcTraceTime.inline.hpp"
34 #include "gc/shared/gcWhen.hpp"
35 #include "gc/shared/vmGCOperations.hpp"
36 #include "logging/log.hpp"
37 #include "memory/metaspace.hpp"
38 #include "memory/resourceArea.hpp"
39 #include "oops/instanceMirrorKlass.hpp"
40 #include "oops/oop.inline.hpp"
41 #include "runtime/init.hpp"
42 #include "runtime/thread.inline.hpp"
43 #include "services/heapDumper.hpp"
44 #include "utilities/align.hpp"
45
46
47 #ifdef ASSERT
48 int CollectedHeap::_fire_out_of_memory_count = 0;
49 #endif
50
51 size_t CollectedHeap::_filler_array_max_size = 0;
52
53 template <>
54 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
55 st->print_cr("GC heap %s", m.is_before ? "before" : "after");
56 st->print_raw(m);
57 }
58
59 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
60 if (!should_log()) {
61 return;
62 }
63
64 double timestamp = fetch_timestamp();
65 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
66 int index = compute_log_index();
67 _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
68 _records[index].timestamp = timestamp;
69 _records[index].data.is_before = before;
70 stringStream st(_records[index].data.buffer(), _records[index].data.size());
71
72 st.print_cr("{Heap %s GC invocations=%u (full %u):",
73 before ? "before" : "after",
74 heap->total_collections(),
75 heap->total_full_collections());
76
77 heap->print_on(&st);
78 st.print_cr("}");
79 }
80
81 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
82 size_t capacity_in_words = capacity() / HeapWordSize;
83
84 return VirtualSpaceSummary(
85 reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end());
86 }
87
88 GCHeapSummary CollectedHeap::create_heap_summary() {
89 VirtualSpaceSummary heap_space = create_heap_space_summary();
90 return GCHeapSummary(heap_space, used());
91 }
92
93 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
94 const MetaspaceSizes meta_space(
95 MetaspaceAux::committed_bytes(),
96 MetaspaceAux::used_bytes(),
97 MetaspaceAux::reserved_bytes());
98 const MetaspaceSizes data_space(
99 MetaspaceAux::committed_bytes(Metaspace::NonClassType),
100 MetaspaceAux::used_bytes(Metaspace::NonClassType),
101 MetaspaceAux::reserved_bytes(Metaspace::NonClassType));
102 const MetaspaceSizes class_space(
103 MetaspaceAux::committed_bytes(Metaspace::ClassType),
104 MetaspaceAux::used_bytes(Metaspace::ClassType),
105 MetaspaceAux::reserved_bytes(Metaspace::ClassType));
106
107 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
108 MetaspaceAux::chunk_free_list_summary(Metaspace::NonClassType);
109 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
110 MetaspaceAux::chunk_free_list_summary(Metaspace::ClassType);
111
112 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
113 ms_chunk_free_list_summary, class_chunk_free_list_summary);
114 }
115
116 void CollectedHeap::print_heap_before_gc() {
117 Universe::print_heap_before_gc();
118 if (_gc_heap_log != NULL) {
119 _gc_heap_log->log_heap_before(this);
120 }
121 }
122
123 void CollectedHeap::print_heap_after_gc() {
124 Universe::print_heap_after_gc();
125 if (_gc_heap_log != NULL) {
126 _gc_heap_log->log_heap_after(this);
127 }
128 }
129
130 void CollectedHeap::print_on_error(outputStream* st) const {
131 st->print_cr("Heap:");
132 print_extended_on(st);
133 st->cr();
134
135 _barrier_set->print_on(st);
136 }
137
138 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
139 const GCHeapSummary& heap_summary = create_heap_summary();
140 gc_tracer->report_gc_heap_summary(when, heap_summary);
141
142 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
143 gc_tracer->report_metaspace_summary(when, metaspace_summary);
144 }
145
146 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
147 trace_heap(GCWhen::BeforeGC, gc_tracer);
148 }
149
150 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
151 trace_heap(GCWhen::AfterGC, gc_tracer);
152 }
153
154 // WhiteBox API support for concurrent collectors. These are the
155 // default implementations, for collectors which don't support this
156 // feature.
157 bool CollectedHeap::supports_concurrent_phase_control() const {
158 return false;
159 }
160
161 const char* const* CollectedHeap::concurrent_phases() const {
162 static const char* const result[] = { NULL };
163 return result;
164 }
165
166 bool CollectedHeap::request_concurrent_phase(const char* phase) {
167 return false;
168 }
169
170 // Memory state functions.
171
172
173 CollectedHeap::CollectedHeap() :
174 _barrier_set(NULL),
175 _is_gc_active(false),
176 _total_collections(0),
177 _total_full_collections(0),
178 _gc_cause(GCCause::_no_gc),
179 _gc_lastcause(GCCause::_no_gc),
180 _defer_initial_card_mark(false) // strengthened by subclass in pre_initialize() below.
181 {
182 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
183 const size_t elements_per_word = HeapWordSize / sizeof(jint);
184 _filler_array_max_size = align_object_size(filler_array_hdr_size() +
185 max_len / elements_per_word);
186
187 NOT_PRODUCT(_promotion_failure_alot_count = 0;)
188 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
189
190 if (UsePerfData) {
191 EXCEPTION_MARK;
192
193 // create the gc cause jvmstat counters
194 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
195 80, GCCause::to_string(_gc_cause), CHECK);
196
197 _perf_gc_lastcause =
198 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
199 80, GCCause::to_string(_gc_lastcause), CHECK);
200 }
201
202 // Create the ring log
203 if (LogEvents) {
204 _gc_heap_log = new GCHeapLog();
205 } else {
206 _gc_heap_log = NULL;
207 }
208 }
209
210 // This interface assumes that it's being called by the
211 // vm thread. It collects the heap assuming that the
212 // heap lock is already held and that we are executing in
213 // the context of the vm thread.
214 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
215 assert(Thread::current()->is_VM_thread(), "Precondition#1");
216 assert(Heap_lock->is_locked(), "Precondition#2");
217 GCCauseSetter gcs(this, cause);
218 switch (cause) {
219 case GCCause::_heap_inspection:
220 case GCCause::_heap_dump:
221 case GCCause::_metadata_GC_threshold : {
222 HandleMark hm;
223 do_full_collection(false); // don't clear all soft refs
224 break;
225 }
226 case GCCause::_metadata_GC_clear_soft_refs: {
227 HandleMark hm;
228 do_full_collection(true); // do clear all soft refs
229 break;
230 }
231 default:
232 ShouldNotReachHere(); // Unexpected use of this function
233 }
234 }
235
236 void CollectedHeap::set_barrier_set(BarrierSet* barrier_set) {
237 _barrier_set = barrier_set;
238 oopDesc::set_bs(_barrier_set);
239 }
240
241 void CollectedHeap::pre_initialize() {
242 // Used for ReduceInitialCardMarks (when COMPILER2 is used);
243 // otherwise remains unused.
244 #if defined(COMPILER2) || INCLUDE_JVMCI
245 _defer_initial_card_mark = is_server_compilation_mode_vm() && ReduceInitialCardMarks && can_elide_tlab_store_barriers()
246 && (DeferInitialCardMark || card_mark_must_follow_store());
247 #else
248 assert(_defer_initial_card_mark == false, "Who would set it?");
249 #endif
250 }
251
252 #ifndef PRODUCT
253 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
254 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
255 for (size_t slot = 0; slot < size; slot += 1) {
256 assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
257 "Found badHeapWordValue in post-allocation check");
258 }
259 }
260 }
261
262 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
263 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
264 for (size_t slot = 0; slot < size; slot += 1) {
265 assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
266 "Found non badHeapWordValue in pre-allocation check");
267 }
268 }
269 }
270 #endif // PRODUCT
271
272 #ifdef ASSERT
273 void CollectedHeap::check_for_valid_allocation_state() {
274 Thread *thread = Thread::current();
275 // How to choose between a pending exception and a potential
276 // OutOfMemoryError? Don't allow pending exceptions.
277 // This is a VM policy failure, so how do we exhaustively test it?
278 assert(!thread->has_pending_exception(),
279 "shouldn't be allocating with pending exception");
280 if (StrictSafepointChecks) {
281 assert(thread->allow_allocation(),
282 "Allocation done by thread for which allocation is blocked "
283 "by No_Allocation_Verifier!");
284 // Allocation of an oop can always invoke a safepoint,
285 // hence, the true argument
286 thread->check_for_valid_safepoint_state(true);
287 }
288 }
289 #endif
290
291 HeapWord* CollectedHeap::allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size) {
292
293 // Retain tlab and allocate object in shared space if
294 // the amount free in the tlab is too large to discard.
295 if (thread->tlab().free() > thread->tlab().refill_waste_limit()) {
296 thread->tlab().record_slow_allocation(size);
297 return NULL;
298 }
299
300 // Discard tlab and allocate a new one.
301 // To minimize fragmentation, the last TLAB may be smaller than the rest.
302 size_t new_tlab_size = thread->tlab().compute_size(size);
303
304 thread->tlab().clear_before_allocation();
305
306 if (new_tlab_size == 0) {
307 return NULL;
308 }
309
310 // Allocate a new TLAB...
311 HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size);
312 if (obj == NULL) {
313 return NULL;
314 }
315
316 AllocTracer::send_allocation_in_new_tlab_event(klass, new_tlab_size * HeapWordSize, size * HeapWordSize);
317
318 if (ZeroTLAB) {
319 // ..and clear it.
320 Copy::zero_to_words(obj, new_tlab_size);
321 } else {
322 // ...and zap just allocated object.
323 #ifdef ASSERT
324 // Skip mangling the space corresponding to the object header to
325 // ensure that the returned space is not considered parsable by
326 // any concurrent GC thread.
327 size_t hdr_size = oopDesc::header_size();
328 Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal);
329 #endif // ASSERT
330 }
331 thread->tlab().fill(obj, obj + size, new_tlab_size);
332 return obj;
333 }
334
335 void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {
336 MemRegion deferred = thread->deferred_card_mark();
337 if (!deferred.is_empty()) {
338 assert(_defer_initial_card_mark, "Otherwise should be empty");
339 {
340 // Verify that the storage points to a parsable object in heap
341 DEBUG_ONLY(oop old_obj = oop(deferred.start());)
342 assert(is_in(old_obj), "Not in allocated heap");
343 assert(!can_elide_initializing_store_barrier(old_obj),
344 "Else should have been filtered in new_store_pre_barrier()");
345 assert(oopDesc::is_oop(old_obj, true), "Not an oop");
346 assert(deferred.word_size() == (size_t)(old_obj->size()),
347 "Mismatch: multiple objects?");
348 }
349 BarrierSet* bs = barrier_set();
350 bs->write_region(deferred);
351 // "Clear" the deferred_card_mark field
352 thread->set_deferred_card_mark(MemRegion());
353 }
354 assert(thread->deferred_card_mark().is_empty(), "invariant");
355 }
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 // Helper for ReduceInitialCardMarks. For performance,
373 // compiled code may elide card-marks for initializing stores
374 // to a newly allocated object along the fast-path. We
375 // compensate for such elided card-marks as follows:
376 // (a) Generational, non-concurrent collectors, such as
377 // GenCollectedHeap(ParNew,DefNew,Tenured) and
378 // ParallelScavengeHeap(ParallelGC, ParallelOldGC)
379 // need the card-mark if and only if the region is
380 // in the old gen, and do not care if the card-mark
381 // succeeds or precedes the initializing stores themselves,
382 // so long as the card-mark is completed before the next
383 // scavenge. For all these cases, we can do a card mark
384 // at the point at which we do a slow path allocation
385 // in the old gen, i.e. in this call.
386 // (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires
387 // in addition that the card-mark for an old gen allocated
388 // object strictly follow any associated initializing stores.
389 // In these cases, the memRegion remembered below is
390 // used to card-mark the entire region either just before the next
391 // slow-path allocation by this thread or just before the next scavenge or
392 // CMS-associated safepoint, whichever of these events happens first.
393 // (The implicit assumption is that the object has been fully
394 // initialized by this point, a fact that we assert when doing the
395 // card-mark.)
396 // (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a
397 // G1 concurrent marking is in progress an SATB (pre-write-)barrier
398 // is used to remember the pre-value of any store. Initializing
399 // stores will not need this barrier, so we need not worry about
400 // compensating for the missing pre-barrier here. Turning now
401 // to the post-barrier, we note that G1 needs a RS update barrier
402 // which simply enqueues a (sequence of) dirty cards which may
403 // optionally be refined by the concurrent update threads. Note
404 // that this barrier need only be applied to a non-young write,
405 // but, like in CMS, because of the presence of concurrent refinement
406 // (much like CMS' precleaning), must strictly follow the oop-store.
407 // Thus, using the same protocol for maintaining the intended
408 // invariants turns out, serendepitously, to be the same for both
409 // G1 and CMS.
410 //
411 // For any future collector, this code should be reexamined with
412 // that specific collector in mind, and the documentation above suitably
413 // extended and updated.
414 oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {
415 // If a previous card-mark was deferred, flush it now.
416 flush_deferred_store_barrier(thread);
417 if (can_elide_initializing_store_barrier(new_obj) ||
418 new_obj->is_typeArray()) {
419 // Arrays of non-references don't need a pre-barrier.
420 // The deferred_card_mark region should be empty
421 // following the flush above.
422 assert(thread->deferred_card_mark().is_empty(), "Error");
423 } else {
424 MemRegion mr((HeapWord*)new_obj, new_obj->size());
425 assert(!mr.is_empty(), "Error");
426 if (_defer_initial_card_mark) {
427 // Defer the card mark
428 thread->set_deferred_card_mark(mr);
429 } else {
430 // Do the card mark
431 BarrierSet* bs = barrier_set();
432 bs->write_region(mr);
433 }
434 }
435 return new_obj;
436 }
437
438 size_t CollectedHeap::filler_array_hdr_size() {
439 return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
440 }
441
442 size_t CollectedHeap::filler_array_min_size() {
443 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
444 }
445
446 #ifdef ASSERT
447 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
448 {
449 assert(words >= min_fill_size(), "too small to fill");
450 assert(is_object_aligned(words), "unaligned size");
451 assert(Universe::heap()->is_in_reserved(start), "not in heap");
452 assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap");
453 }
454
455 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
456 {
457 if (ZapFillerObjects && zap) {
458 Copy::fill_to_words(start + filler_array_hdr_size(),
459 words - filler_array_hdr_size(), 0XDEAFBABE);
460 }
461 }
462 #endif // ASSERT
463
464 void
465 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
466 {
467 assert(words >= filler_array_min_size(), "too small for an array");
468 assert(words <= filler_array_max_size(), "too big for a single object");
469
470 const size_t payload_size = words - filler_array_hdr_size();
471 const size_t len = payload_size * HeapWordSize / sizeof(jint);
472 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
473
474 // Set the length first for concurrent GC.
475 ((arrayOop)start)->set_length((int)len);
476 post_allocation_setup_common(Universe::intArrayKlassObj(), start);
477 DEBUG_ONLY(zap_filler_array(start, words, zap);)
478 }
479
480 void
481 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
482 {
483 assert(words <= filler_array_max_size(), "too big for a single object");
484
485 if (words >= filler_array_min_size()) {
486 fill_with_array(start, words, zap);
487 } else if (words > 0) {
488 assert(words == min_fill_size(), "unaligned size");
489 post_allocation_setup_common(SystemDictionary::Object_klass(), start);
490 }
491 }
492
493 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
494 {
495 DEBUG_ONLY(fill_args_check(start, words);)
496 HandleMark hm; // Free handles before leaving.
497 fill_with_object_impl(start, words, zap);
498 }
499
500 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
501 {
502 DEBUG_ONLY(fill_args_check(start, words);)
503 HandleMark hm; // Free handles before leaving.
504
505 // Multiple objects may be required depending on the filler array maximum size. Fill
506 // the range up to that with objects that are filler_array_max_size sized. The
507 // remainder is filled with a single object.
508 const size_t min = min_fill_size();
509 const size_t max = filler_array_max_size();
510 while (words > max) {
511 const size_t cur = (words - max) >= min ? max : max - min;
512 fill_with_array(start, cur, zap);
513 start += cur;
514 words -= cur;
515 }
516
517 fill_with_object_impl(start, words, zap);
518 }
519
520 HeapWord* CollectedHeap::allocate_new_tlab(size_t size) {
521 guarantee(false, "thread-local allocation buffers not supported");
522 return NULL;
523 }
524
525 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
526 // The second disjunct in the assertion below makes a concession
527 // for the start-up verification done while the VM is being
528 // created. Callers be careful that you know that mutators
529 // aren't going to interfere -- for instance, this is permissible
530 // if we are still single-threaded and have either not yet
531 // started allocating (nothing much to verify) or we have
532 // started allocating but are now a full-fledged JavaThread
533 // (and have thus made our TLAB's) available for filling.
534 assert(SafepointSynchronize::is_at_safepoint() ||
535 !is_init_completed(),
536 "Should only be called at a safepoint or at start-up"
537 " otherwise concurrent mutator activity may make heap "
538 " unparsable again");
539 const bool use_tlab = UseTLAB;
540 const bool deferred = _defer_initial_card_mark;
541 // The main thread starts allocating via a TLAB even before it
542 // has added itself to the threads list at vm boot-up.
543 assert(!use_tlab || Threads::first() != NULL,
544 "Attempt to fill tlabs before main thread has been added"
545 " to threads list is doomed to failure!");
546 for (JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
547 if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
548 #if defined(COMPILER2) || INCLUDE_JVMCI
549 // The deferred store barriers must all have been flushed to the
550 // card-table (or other remembered set structure) before GC starts
551 // processing the card-table (or other remembered set).
552 if (deferred) flush_deferred_store_barrier(thread);
553 #else
554 assert(!deferred, "Should be false");
555 assert(thread->deferred_card_mark().is_empty(), "Should be empty");
556 #endif
557 }
558 }
559
560 void CollectedHeap::accumulate_statistics_all_tlabs() {
561 if (UseTLAB) {
562 assert(SafepointSynchronize::is_at_safepoint() ||
563 !is_init_completed(),
564 "should only accumulate statistics on tlabs at safepoint");
565
566 ThreadLocalAllocBuffer::accumulate_statistics_before_gc();
567 }
568 }
569
570 void CollectedHeap::resize_all_tlabs() {
571 if (UseTLAB) {
572 assert(SafepointSynchronize::is_at_safepoint() ||
573 !is_init_completed(),
574 "should only resize tlabs at safepoint");
575
576 ThreadLocalAllocBuffer::resize_all_tlabs();
577 }
578 }
579
580 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
581 assert(timer != NULL, "timer is null");
582 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
583 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
584 HeapDumper::dump_heap();
585 }
586
587 LogTarget(Trace, gc, classhisto) lt;
588 if (lt.is_enabled()) {
589 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
590 ResourceMark rm;
591 LogStream ls(lt);
592 VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
593 inspector.doit();
594 }
595 }
596
597 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
598 full_gc_dump(timer, true);
599 }
600
601 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
602 full_gc_dump(timer, false);
603 }
604
605 void CollectedHeap::initialize_reserved_region(HeapWord *start, HeapWord *end) {
606 // It is important to do this in a way such that concurrent readers can't
607 // temporarily think something is in the heap. (Seen this happen in asserts.)
608 _reserved.set_word_size(0);
609 _reserved.set_start(start);
610 _reserved.set_end(end);
611 }