1 /*
  2  * Copyright (c) 2001, 2018, 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/gcWhen.hpp"
 36 #include "gc/shared/vmGCOperations.hpp"
 37 #include "logging/log.hpp"
 38 #include "memory/metaspace.hpp"
 39 #include "memory/resourceArea.hpp"
 40 #include "oops/instanceMirrorKlass.hpp"
 41 #include "oops/oop.inline.hpp"
 42 #include "runtime/handles.inline.hpp"
 43 #include "runtime/init.hpp"
 44 #include "runtime/thread.inline.hpp"
 45 #include "runtime/threadSMR.hpp"
 46 #include "runtime/vmThread.hpp"
 47 #include "services/heapDumper.hpp"
 48 #include "utilities/align.hpp"
 49 
 50 class ClassLoaderData;
 51 
 52 #ifdef ASSERT
 53 int CollectedHeap::_fire_out_of_memory_count = 0;
 54 #endif
 55 
 56 size_t CollectedHeap::_filler_array_max_size = 0;
 57 
 58 template <>
 59 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
 60   st->print_cr("GC heap %s", m.is_before ? "before" : "after");
 61   st->print_raw(m);
 62 }
 63 
 64 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
 65   if (!should_log()) {
 66     return;
 67   }
 68 
 69   double timestamp = fetch_timestamp();
 70   MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
 71   int index = compute_log_index();
 72   _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
 73   _records[index].timestamp = timestamp;
 74   _records[index].data.is_before = before;
 75   stringStream st(_records[index].data.buffer(), _records[index].data.size());
 76 
 77   st.print_cr("{Heap %s GC invocations=%u (full %u):",
 78                  before ? "before" : "after",
 79                  heap->total_collections(),
 80                  heap->total_full_collections());
 81 
 82   heap->print_on(&st);
 83   st.print_cr("}");
 84 }
 85 
 86 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
 87   size_t capacity_in_words = capacity() / HeapWordSize;
 88 
 89   return VirtualSpaceSummary(
 90     reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end());
 91 }
 92 
 93 GCHeapSummary CollectedHeap::create_heap_summary() {
 94   VirtualSpaceSummary heap_space = create_heap_space_summary();
 95   return GCHeapSummary(heap_space, used());
 96 }
 97 
 98 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
 99   const MetaspaceSizes meta_space(
100       MetaspaceUtils::committed_bytes(),
101       MetaspaceUtils::used_bytes(),
102       MetaspaceUtils::reserved_bytes());
103   const MetaspaceSizes data_space(
104       MetaspaceUtils::committed_bytes(Metaspace::NonClassType),
105       MetaspaceUtils::used_bytes(Metaspace::NonClassType),
106       MetaspaceUtils::reserved_bytes(Metaspace::NonClassType));
107   const MetaspaceSizes class_space(
108       MetaspaceUtils::committed_bytes(Metaspace::ClassType),
109       MetaspaceUtils::used_bytes(Metaspace::ClassType),
110       MetaspaceUtils::reserved_bytes(Metaspace::ClassType));
111 
112   const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
113     MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
114   const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
115     MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
116 
117   return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
118                           ms_chunk_free_list_summary, class_chunk_free_list_summary);
119 }
120 
121 void CollectedHeap::print_heap_before_gc() {
122   Universe::print_heap_before_gc();
123   if (_gc_heap_log != NULL) {
124     _gc_heap_log->log_heap_before(this);
125   }
126 }
127 
128 void CollectedHeap::print_heap_after_gc() {
129   Universe::print_heap_after_gc();
130   if (_gc_heap_log != NULL) {
131     _gc_heap_log->log_heap_after(this);
132   }
133 }
134 
135 void CollectedHeap::print_on_error(outputStream* st) const {
136   st->print_cr("Heap:");
137   print_extended_on(st);
138   st->cr();
139 
140   BarrierSet::barrier_set()->print_on(st);
141 }
142 
143 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
144   const GCHeapSummary& heap_summary = create_heap_summary();
145   gc_tracer->report_gc_heap_summary(when, heap_summary);
146 
147   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
148   gc_tracer->report_metaspace_summary(when, metaspace_summary);
149 }
150 
151 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
152   trace_heap(GCWhen::BeforeGC, gc_tracer);
153 }
154 
155 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
156   trace_heap(GCWhen::AfterGC, gc_tracer);
157 }
158 
159 // WhiteBox API support for concurrent collectors.  These are the
160 // default implementations, for collectors which don't support this
161 // feature.
162 bool CollectedHeap::supports_concurrent_phase_control() const {
163   return false;
164 }
165 
166 const char* const* CollectedHeap::concurrent_phases() const {
167   static const char* const result[] = { NULL };
168   return result;
169 }
170 
171 bool CollectedHeap::request_concurrent_phase(const char* phase) {
172   return false;
173 }
174 
175 bool CollectedHeap::is_oop(oop object) const {
176   if (!check_obj_alignment(object)) {
177     return false;
178   }
179 
180   if (!is_in_reserved(object)) {
181     return false;
182   }
183 
184   if (is_in_reserved(object->klass_or_null())) {
185     return false;
186   }
187 
188   return true;
189 }
190 
191 // Memory state functions.
192 
193 
194 CollectedHeap::CollectedHeap() :
195   _is_gc_active(false),
196   _total_collections(0),
197   _total_full_collections(0),
198   _gc_cause(GCCause::_no_gc),
199   _gc_lastcause(GCCause::_no_gc)
200 {
201   const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
202   const size_t elements_per_word = HeapWordSize / sizeof(jint);
203   _filler_array_max_size = align_object_size(filler_array_hdr_size() +
204                                              max_len / elements_per_word);
205 
206   NOT_PRODUCT(_promotion_failure_alot_count = 0;)
207   NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
208 
209   if (UsePerfData) {
210     EXCEPTION_MARK;
211 
212     // create the gc cause jvmstat counters
213     _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
214                              80, GCCause::to_string(_gc_cause), CHECK);
215 
216     _perf_gc_lastcause =
217                 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
218                              80, GCCause::to_string(_gc_lastcause), CHECK);
219   }
220 
221   // Create the ring log
222   if (LogEvents) {
223     _gc_heap_log = new GCHeapLog();
224   } else {
225     _gc_heap_log = NULL;
226   }
227 }
228 
229 // This interface assumes that it's being called by the
230 // vm thread. It collects the heap assuming that the
231 // heap lock is already held and that we are executing in
232 // the context of the vm thread.
233 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
234   assert(Thread::current()->is_VM_thread(), "Precondition#1");
235   assert(Heap_lock->is_locked(), "Precondition#2");
236   GCCauseSetter gcs(this, cause);
237   switch (cause) {
238     case GCCause::_heap_inspection:
239     case GCCause::_heap_dump:
240     case GCCause::_metadata_GC_threshold : {
241       HandleMark hm;
242       do_full_collection(false);        // don't clear all soft refs
243       break;
244     }
245     case GCCause::_metadata_GC_clear_soft_refs: {
246       HandleMark hm;
247       do_full_collection(true);         // do clear all soft refs
248       break;
249     }
250     default:
251       ShouldNotReachHere(); // Unexpected use of this function
252   }
253 }
254 
255 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
256                                                             size_t word_size,
257                                                             Metaspace::MetadataType mdtype) {
258   uint loop_count = 0;
259   uint gc_count = 0;
260   uint full_gc_count = 0;
261 
262   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
263 
264   do {
265     MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
266     if (result != NULL) {
267       return result;
268     }
269 
270     if (GCLocker::is_active_and_needs_gc()) {
271       // If the GCLocker is active, just expand and allocate.
272       // If that does not succeed, wait if this thread is not
273       // in a critical section itself.
274       result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
275       if (result != NULL) {
276         return result;
277       }
278       JavaThread* jthr = JavaThread::current();
279       if (!jthr->in_critical()) {
280         // Wait for JNI critical section to be exited
281         GCLocker::stall_until_clear();
282         // The GC invoked by the last thread leaving the critical
283         // section will be a young collection and a full collection
284         // is (currently) needed for unloading classes so continue
285         // to the next iteration to get a full GC.
286         continue;
287       } else {
288         if (CheckJNICalls) {
289           fatal("Possible deadlock due to allocating while"
290                 " in jni critical section");
291         }
292         return NULL;
293       }
294     }
295 
296     {  // Need lock to get self consistent gc_count's
297       MutexLocker ml(Heap_lock);
298       gc_count      = Universe::heap()->total_collections();
299       full_gc_count = Universe::heap()->total_full_collections();
300     }
301 
302     // Generate a VM operation
303     VM_CollectForMetadataAllocation op(loader_data,
304                                        word_size,
305                                        mdtype,
306                                        gc_count,
307                                        full_gc_count,
308                                        GCCause::_metadata_GC_threshold);
309     VMThread::execute(&op);
310 
311     // If GC was locked out, try again. Check before checking success because the
312     // prologue could have succeeded and the GC still have been locked out.
313     if (op.gc_locked()) {
314       continue;
315     }
316 
317     if (op.prologue_succeeded()) {
318       return op.result();
319     }
320     loop_count++;
321     if ((QueuedAllocationWarningCount > 0) &&
322         (loop_count % QueuedAllocationWarningCount == 0)) {
323       log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
324                             " size=" SIZE_FORMAT, loop_count, word_size);
325     }
326   } while (true);  // Until a GC is done
327 }
328 
329 #ifndef PRODUCT
330 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
331   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
332     for (size_t slot = 0; slot < size; slot += 1) {
333       assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
334              "Found badHeapWordValue in post-allocation check");
335     }
336   }
337 }
338 
339 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
340   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
341     for (size_t slot = 0; slot < size; slot += 1) {
342       assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
343              "Found non badHeapWordValue in pre-allocation check");
344     }
345   }
346 }
347 #endif // PRODUCT
348 
349 #ifdef ASSERT
350 void CollectedHeap::check_for_valid_allocation_state() {
351   Thread *thread = Thread::current();
352   // How to choose between a pending exception and a potential
353   // OutOfMemoryError?  Don't allow pending exceptions.
354   // This is a VM policy failure, so how do we exhaustively test it?
355   assert(!thread->has_pending_exception(),
356          "shouldn't be allocating with pending exception");
357   if (StrictSafepointChecks) {
358     assert(thread->allow_allocation(),
359            "Allocation done by thread for which allocation is blocked "
360            "by No_Allocation_Verifier!");
361     // Allocation of an oop can always invoke a safepoint,
362     // hence, the true argument
363     thread->check_for_valid_safepoint_state(true);
364   }
365 }
366 #endif
367 
368 HeapWord* CollectedHeap::obj_allocate_raw(Klass* klass, size_t size,
369                                           bool* gc_overhead_limit_was_exceeded, TRAPS) {
370   if (UseTLAB) {
371     HeapWord* result = allocate_from_tlab(klass, size, THREAD);
372     if (result != NULL) {
373       return result;
374     }
375   }
376   return Universe::heap()->mem_allocate(size, gc_overhead_limit_was_exceeded);
377 }
378 
379 HeapWord* CollectedHeap::allocate_from_tlab_slow(Klass* klass, size_t size, TRAPS) {
380   ThreadLocalAllocBuffer& tlab = THREAD->tlab();
381 
382   // Retain tlab and allocate object in shared space if
383   // the amount free in the tlab is too large to discard.
384   if (tlab.free() > tlab.refill_waste_limit()) {
385     tlab.record_slow_allocation(size);
386     return NULL;
387   }
388 
389   // Discard tlab and allocate a new one.
390   // To minimize fragmentation, the last TLAB may be smaller than the rest.
391   size_t new_tlab_size = tlab.compute_size(size);
392 
393   tlab.clear_before_allocation();
394 
395   if (new_tlab_size == 0) {
396     return NULL;
397   }
398 
399   // Allocate a new TLAB requesting new_tlab_size. Any size
400   // between minimal and new_tlab_size is accepted.
401   size_t actual_tlab_size = 0;
402   size_t min_tlab_size = ThreadLocalAllocBuffer::compute_min_size(size);
403   HeapWord* obj = Universe::heap()->allocate_new_tlab(min_tlab_size, new_tlab_size, &actual_tlab_size);
404   if (obj == NULL) {
405     assert(actual_tlab_size == 0, "Allocation failed, but actual size was updated. min: " SIZE_FORMAT ", desired: " SIZE_FORMAT ", actual: " SIZE_FORMAT,
406            min_tlab_size, new_tlab_size, actual_tlab_size);
407     return NULL;
408   }
409   assert(actual_tlab_size != 0, "Allocation succeeded but actual size not updated. obj at: " PTR_FORMAT " min: " SIZE_FORMAT ", desired: " SIZE_FORMAT,
410          p2i(obj), min_tlab_size, new_tlab_size);
411 
412   AllocTracer::send_allocation_in_new_tlab(klass, obj, actual_tlab_size * HeapWordSize, size * HeapWordSize, THREAD);
413 
414   if (ZeroTLAB) {
415     // ..and clear it.
416     Copy::zero_to_words(obj, actual_tlab_size);
417   } else {
418     // ...and zap just allocated object.
419 #ifdef ASSERT
420     // Skip mangling the space corresponding to the object header to
421     // ensure that the returned space is not considered parsable by
422     // any concurrent GC thread.
423     size_t hdr_size = oopDesc::header_size();
424     Copy::fill_to_words(obj + hdr_size, actual_tlab_size - hdr_size, badHeapWordVal);
425 #endif // ASSERT
426   }
427   tlab.fill(obj, obj + size, actual_tlab_size);
428   return obj;
429 }
430 
431 size_t CollectedHeap::max_tlab_size() const {
432   // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
433   // This restriction could be removed by enabling filling with multiple arrays.
434   // If we compute that the reasonable way as
435   //    header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
436   // we'll overflow on the multiply, so we do the divide first.
437   // We actually lose a little by dividing first,
438   // but that just makes the TLAB  somewhat smaller than the biggest array,
439   // which is fine, since we'll be able to fill that.
440   size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
441               sizeof(jint) *
442               ((juint) max_jint / (size_t) HeapWordSize);
443   return align_down(max_int_size, MinObjAlignment);
444 }
445 
446 size_t CollectedHeap::filler_array_hdr_size() {
447   return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
448 }
449 
450 size_t CollectedHeap::filler_array_min_size() {
451   return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
452 }
453 
454 #ifdef ASSERT
455 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
456 {
457   assert(words >= min_fill_size(), "too small to fill");
458   assert(is_object_aligned(words), "unaligned size");
459   assert(Universe::heap()->is_in_reserved(start), "not in heap");
460   assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap");
461 }
462 
463 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
464 {
465   if (ZapFillerObjects && zap) {
466     Copy::fill_to_words(start + filler_array_hdr_size(),
467                         words - filler_array_hdr_size(), 0XDEAFBABE);
468   }
469 }
470 #endif // ASSERT
471 
472 void
473 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
474 {
475   assert(words >= filler_array_min_size(), "too small for an array");
476   assert(words <= filler_array_max_size(), "too big for a single object");
477 
478   const size_t payload_size = words - filler_array_hdr_size();
479   const size_t len = payload_size * HeapWordSize / sizeof(jint);
480   assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
481 
482   // Set the length first for concurrent GC.
483   ((arrayOop)start)->set_length((int)len);
484   post_allocation_setup_common(Universe::intArrayKlassObj(), start);
485   DEBUG_ONLY(zap_filler_array(start, words, zap);)
486 }
487 
488 void
489 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
490 {
491   assert(words <= filler_array_max_size(), "too big for a single object");
492 
493   if (words >= filler_array_min_size()) {
494     fill_with_array(start, words, zap);
495   } else if (words > 0) {
496     assert(words == min_fill_size(), "unaligned size");
497     post_allocation_setup_common(SystemDictionary::Object_klass(), start);
498   }
499 }
500 
501 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
502 {
503   DEBUG_ONLY(fill_args_check(start, words);)
504   HandleMark hm;  // Free handles before leaving.
505   fill_with_object_impl(start, words, zap);
506 }
507 
508 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
509 {
510   DEBUG_ONLY(fill_args_check(start, words);)
511   HandleMark hm;  // Free handles before leaving.
512 
513   // Multiple objects may be required depending on the filler array maximum size. Fill
514   // the range up to that with objects that are filler_array_max_size sized. The
515   // remainder is filled with a single object.
516   const size_t min = min_fill_size();
517   const size_t max = filler_array_max_size();
518   while (words > max) {
519     const size_t cur = (words - max) >= min ? max : max - min;
520     fill_with_array(start, cur, zap);
521     start += cur;
522     words -= cur;
523   }
524 
525   fill_with_object_impl(start, words, zap);
526 }
527 
528 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
529                                            size_t requested_size,
530                                            size_t* actual_size) {
531   guarantee(false, "thread-local allocation buffers not supported");
532   return NULL;
533 }
534 
535 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
536   // The second disjunct in the assertion below makes a concession
537   // for the start-up verification done while the VM is being
538   // created. Callers be careful that you know that mutators
539   // aren't going to interfere -- for instance, this is permissible
540   // if we are still single-threaded and have either not yet
541   // started allocating (nothing much to verify) or we have
542   // started allocating but are now a full-fledged JavaThread
543   // (and have thus made our TLAB's) available for filling.
544   assert(SafepointSynchronize::is_at_safepoint() ||
545          !is_init_completed(),
546          "Should only be called at a safepoint or at start-up"
547          " otherwise concurrent mutator activity may make heap "
548          " unparsable again");
549   const bool use_tlab = UseTLAB;
550   // The main thread starts allocating via a TLAB even before it
551   // has added itself to the threads list at vm boot-up.
552   JavaThreadIteratorWithHandle jtiwh;
553   assert(!use_tlab || jtiwh.length() > 0,
554          "Attempt to fill tlabs before main thread has been added"
555          " to threads list is doomed to failure!");
556   BarrierSet *bs = BarrierSet::barrier_set();
557   for (; JavaThread *thread = jtiwh.next(); ) {
558      if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
559      bs->make_parsable(thread);
560   }
561 }
562 
563 void CollectedHeap::accumulate_statistics_all_tlabs() {
564   if (UseTLAB) {
565     assert(SafepointSynchronize::is_at_safepoint() ||
566          !is_init_completed(),
567          "should only accumulate statistics on tlabs at safepoint");
568 
569     ThreadLocalAllocBuffer::accumulate_statistics_before_gc();
570   }
571 }
572 
573 void CollectedHeap::resize_all_tlabs() {
574   if (UseTLAB) {
575     assert(SafepointSynchronize::is_at_safepoint() ||
576          !is_init_completed(),
577          "should only resize tlabs at safepoint");
578 
579     ThreadLocalAllocBuffer::resize_all_tlabs();
580   }
581 }
582 
583 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
584   assert(timer != NULL, "timer is null");
585   if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
586     GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
587     HeapDumper::dump_heap();
588   }
589 
590   LogTarget(Trace, gc, classhisto) lt;
591   if (lt.is_enabled()) {
592     GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
593     ResourceMark rm;
594     LogStream ls(lt);
595     VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
596     inspector.doit();
597   }
598 }
599 
600 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
601   full_gc_dump(timer, true);
602 }
603 
604 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
605   full_gc_dump(timer, false);
606 }
607 
608 void CollectedHeap::initialize_reserved_region(HeapWord *start, HeapWord *end) {
609   // It is important to do this in a way such that concurrent readers can't
610   // temporarily think something is in the heap.  (Seen this happen in asserts.)
611   _reserved.set_word_size(0);
612   _reserved.set_start(start);
613   _reserved.set_end(end);
614 }
615 
616 void CollectedHeap::post_initialize() {
617   initialize_serviceability();
618 }
619 
620 #ifndef PRODUCT
621 
622 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
623   // Access to count is not atomic; the value does not have to be exact.
624   if (PromotionFailureALot) {
625     const size_t gc_num = total_collections();
626     const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
627     if (elapsed_gcs >= PromotionFailureALotInterval) {
628       // Test for unsigned arithmetic wrap-around.
629       if (++*count >= PromotionFailureALotCount) {
630         *count = 0;
631         return true;
632       }
633     }
634   }
635   return false;
636 }
637 
638 bool CollectedHeap::promotion_should_fail() {
639   return promotion_should_fail(&_promotion_failure_alot_count);
640 }
641 
642 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
643   if (PromotionFailureALot) {
644     _promotion_failure_alot_gc_number = total_collections();
645     *count = 0;
646   }
647 }
648 
649 void CollectedHeap::reset_promotion_should_fail() {
650   reset_promotion_should_fail(&_promotion_failure_alot_count);
651 }
652 
653 #endif  // #ifndef PRODUCT
654 
655 bool CollectedHeap::supports_object_pinning() const {
656   return false;
657 }
658 
659 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) {
660   ShouldNotReachHere();
661   return NULL;
662 }
663 
664 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
665   ShouldNotReachHere();
666 }
667 
668 void CollectedHeap::deduplicate_string(oop str) {
669   // Do nothing, unless overridden in subclass.
670 }