Thu, 15 Aug 2013 10:52:18 +0200
7145569: G1: optimize nmethods scanning
Summary: Add a list of nmethods to the RSet for a region that contain references into the region. Skip scanning the code cache during root scanning and scan the nmethod lists during RSet scanning instead.
Reviewed-by: tschatzl, brutisso, mgerdin, twisti, kvn
1 /*
2 * Copyright (c) 2001, 2013, 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 */
25 #ifndef SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP
28 #include "gc_interface/gcCause.hpp"
29 #include "gc_implementation/shared/gcWhen.hpp"
30 #include "memory/allocation.hpp"
31 #include "memory/barrierSet.hpp"
32 #include "runtime/handles.hpp"
33 #include "runtime/perfData.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "utilities/events.hpp"
37 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
38 // is an abstract class: there may be many different kinds of heaps. This
39 // class defines the functions that a heap must implement, and contains
40 // infrastructure common to all heaps.
42 class AdaptiveSizePolicy;
43 class BarrierSet;
44 class CollectorPolicy;
45 class GCHeapSummary;
46 class GCTimer;
47 class GCTracer;
48 class MetaspaceSummary;
49 class Thread;
50 class ThreadClosure;
51 class VirtualSpaceSummary;
52 class nmethod;
54 class GCMessage : public FormatBuffer<1024> {
55 public:
56 bool is_before;
58 public:
59 GCMessage() {}
60 };
62 class GCHeapLog : public EventLogBase<GCMessage> {
63 private:
64 void log_heap(bool before);
66 public:
67 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
69 void log_heap_before() {
70 log_heap(true);
71 }
72 void log_heap_after() {
73 log_heap(false);
74 }
75 };
77 //
78 // CollectedHeap
79 // SharedHeap
80 // GenCollectedHeap
81 // G1CollectedHeap
82 // ParallelScavengeHeap
83 //
84 class CollectedHeap : public CHeapObj<mtInternal> {
85 friend class VMStructs;
86 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
88 #ifdef ASSERT
89 static int _fire_out_of_memory_count;
90 #endif
92 // Used for filler objects (static, but initialized in ctor).
93 static size_t _filler_array_max_size;
95 GCHeapLog* _gc_heap_log;
97 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used
98 bool _defer_initial_card_mark;
100 protected:
101 MemRegion _reserved;
102 BarrierSet* _barrier_set;
103 bool _is_gc_active;
104 uint _n_par_threads;
106 unsigned int _total_collections; // ... started
107 unsigned int _total_full_collections; // ... started
108 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
109 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
111 // Reason for current garbage collection. Should be set to
112 // a value reflecting no collection between collections.
113 GCCause::Cause _gc_cause;
114 GCCause::Cause _gc_lastcause;
115 PerfStringVariable* _perf_gc_cause;
116 PerfStringVariable* _perf_gc_lastcause;
118 // Constructor
119 CollectedHeap();
121 // Do common initializations that must follow instance construction,
122 // for example, those needing virtual calls.
123 // This code could perhaps be moved into initialize() but would
124 // be slightly more awkward because we want the latter to be a
125 // pure virtual.
126 void pre_initialize();
128 // Create a new tlab. All TLAB allocations must go through this.
129 virtual HeapWord* allocate_new_tlab(size_t size);
131 // Accumulate statistics on all tlabs.
132 virtual void accumulate_statistics_all_tlabs();
134 // Reinitialize tlabs before resuming mutators.
135 virtual void resize_all_tlabs();
137 // Allocate from the current thread's TLAB, with broken-out slow path.
138 inline static HeapWord* allocate_from_tlab(KlassHandle klass, Thread* thread, size_t size);
139 static HeapWord* allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size);
141 // Allocate an uninitialized block of the given size, or returns NULL if
142 // this is impossible.
143 inline static HeapWord* common_mem_allocate_noinit(KlassHandle klass, size_t size, TRAPS);
145 // Like allocate_init, but the block returned by a successful allocation
146 // is guaranteed initialized to zeros.
147 inline static HeapWord* common_mem_allocate_init(KlassHandle klass, size_t size, TRAPS);
149 // Helper functions for (VM) allocation.
150 inline static void post_allocation_setup_common(KlassHandle klass, HeapWord* obj);
151 inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
152 HeapWord* objPtr);
154 inline static void post_allocation_setup_obj(KlassHandle klass, HeapWord* obj);
156 inline static void post_allocation_setup_array(KlassHandle klass,
157 HeapWord* obj, int length);
159 // Clears an allocated object.
160 inline static void init_obj(HeapWord* obj, size_t size);
162 // Filler object utilities.
163 static inline size_t filler_array_hdr_size();
164 static inline size_t filler_array_min_size();
166 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
167 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
169 // Fill with a single array; caller must ensure filler_array_min_size() <=
170 // words <= filler_array_max_size().
171 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
173 // Fill with a single object (either an int array or a java.lang.Object).
174 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
176 virtual void trace_heap(GCWhen::Type when, GCTracer* tracer);
178 // Verification functions
179 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
180 PRODUCT_RETURN;
181 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
182 PRODUCT_RETURN;
183 debug_only(static void check_for_valid_allocation_state();)
185 public:
186 enum Name {
187 Abstract,
188 SharedHeap,
189 GenCollectedHeap,
190 ParallelScavengeHeap,
191 G1CollectedHeap
192 };
194 static inline size_t filler_array_max_size() {
195 return _filler_array_max_size;
196 }
198 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
200 /**
201 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
202 * and JNI_OK on success.
203 */
204 virtual jint initialize() = 0;
206 // In many heaps, there will be a need to perform some initialization activities
207 // after the Universe is fully formed, but before general heap allocation is allowed.
208 // This is the correct place to place such initialization methods.
209 virtual void post_initialize() = 0;
211 MemRegion reserved_region() const { return _reserved; }
212 address base() const { return (address)reserved_region().start(); }
214 virtual size_t capacity() const = 0;
215 virtual size_t used() const = 0;
217 // Return "true" if the part of the heap that allocates Java
218 // objects has reached the maximal committed limit that it can
219 // reach, without a garbage collection.
220 virtual bool is_maximal_no_gc() const = 0;
222 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
223 // memory that the vm could make available for storing 'normal' java objects.
224 // This is based on the reserved address space, but should not include space
225 // that the vm uses internally for bookkeeping or temporary storage
226 // (e.g., in the case of the young gen, one of the survivor
227 // spaces).
228 virtual size_t max_capacity() const = 0;
230 // Returns "TRUE" if "p" points into the reserved area of the heap.
231 bool is_in_reserved(const void* p) const {
232 return _reserved.contains(p);
233 }
235 bool is_in_reserved_or_null(const void* p) const {
236 return p == NULL || is_in_reserved(p);
237 }
239 // Returns "TRUE" iff "p" points into the committed areas of the heap.
240 // Since this method can be expensive in general, we restrict its
241 // use to assertion checking only.
242 virtual bool is_in(const void* p) const = 0;
244 bool is_in_or_null(const void* p) const {
245 return p == NULL || is_in(p);
246 }
248 bool is_in_place(Metadata** p) {
249 return !Universe::heap()->is_in(p);
250 }
251 bool is_in_place(oop* p) { return Universe::heap()->is_in(p); }
252 bool is_in_place(narrowOop* p) {
253 oop o = oopDesc::load_decode_heap_oop_not_null(p);
254 return Universe::heap()->is_in((const void*)o);
255 }
257 // Let's define some terms: a "closed" subset of a heap is one that
258 //
259 // 1) contains all currently-allocated objects, and
260 //
261 // 2) is closed under reference: no object in the closed subset
262 // references one outside the closed subset.
263 //
264 // Membership in a heap's closed subset is useful for assertions.
265 // Clearly, the entire heap is a closed subset, so the default
266 // implementation is to use "is_in_reserved". But this may not be too
267 // liberal to perform useful checking. Also, the "is_in" predicate
268 // defines a closed subset, but may be too expensive, since "is_in"
269 // verifies that its argument points to an object head. The
270 // "closed_subset" method allows a heap to define an intermediate
271 // predicate, allowing more precise checking than "is_in_reserved" at
272 // lower cost than "is_in."
274 // One important case is a heap composed of disjoint contiguous spaces,
275 // such as the Garbage-First collector. Such heaps have a convenient
276 // closed subset consisting of the allocated portions of those
277 // contiguous spaces.
279 // Return "TRUE" iff the given pointer points into the heap's defined
280 // closed subset (which defaults to the entire heap).
281 virtual bool is_in_closed_subset(const void* p) const {
282 return is_in_reserved(p);
283 }
285 bool is_in_closed_subset_or_null(const void* p) const {
286 return p == NULL || is_in_closed_subset(p);
287 }
289 #ifdef ASSERT
290 // Returns true if "p" is in the part of the
291 // heap being collected.
292 virtual bool is_in_partial_collection(const void *p) = 0;
293 #endif
295 // An object is scavengable if its location may move during a scavenge.
296 // (A scavenge is a GC which is not a full GC.)
297 virtual bool is_scavengable(const void *p) = 0;
299 void set_gc_cause(GCCause::Cause v) {
300 if (UsePerfData) {
301 _gc_lastcause = _gc_cause;
302 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
303 _perf_gc_cause->set_value(GCCause::to_string(v));
304 }
305 _gc_cause = v;
306 }
307 GCCause::Cause gc_cause() { return _gc_cause; }
309 // Number of threads currently working on GC tasks.
310 uint n_par_threads() { return _n_par_threads; }
312 // May be overridden to set additional parallelism.
313 virtual void set_par_threads(uint t) { _n_par_threads = t; };
315 // Allocate and initialize instances of Class
316 static oop Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS);
318 // General obj/array allocation facilities.
319 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
320 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
321 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS);
323 inline static void post_allocation_install_obj_klass(KlassHandle klass,
324 oop obj);
326 // Raw memory allocation facilities
327 // The obj and array allocate methods are covers for these methods.
328 // mem_allocate() should never be
329 // called to allocate TLABs, only individual objects.
330 virtual HeapWord* mem_allocate(size_t size,
331 bool* gc_overhead_limit_was_exceeded) = 0;
333 // Utilities for turning raw memory into filler objects.
334 //
335 // min_fill_size() is the smallest region that can be filled.
336 // fill_with_objects() can fill arbitrary-sized regions of the heap using
337 // multiple objects. fill_with_object() is for regions known to be smaller
338 // than the largest array of integers; it uses a single object to fill the
339 // region and has slightly less overhead.
340 static size_t min_fill_size() {
341 return size_t(align_object_size(oopDesc::header_size()));
342 }
344 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
346 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
347 static void fill_with_object(MemRegion region, bool zap = true) {
348 fill_with_object(region.start(), region.word_size(), zap);
349 }
350 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
351 fill_with_object(start, pointer_delta(end, start), zap);
352 }
354 // Some heaps may offer a contiguous region for shared non-blocking
355 // allocation, via inlined code (by exporting the address of the top and
356 // end fields defining the extent of the contiguous allocation region.)
358 // This function returns "true" iff the heap supports this kind of
359 // allocation. (Default is "no".)
360 virtual bool supports_inline_contig_alloc() const {
361 return false;
362 }
363 // These functions return the addresses of the fields that define the
364 // boundaries of the contiguous allocation area. (These fields should be
365 // physically near to one another.)
366 virtual HeapWord** top_addr() const {
367 guarantee(false, "inline contiguous allocation not supported");
368 return NULL;
369 }
370 virtual HeapWord** end_addr() const {
371 guarantee(false, "inline contiguous allocation not supported");
372 return NULL;
373 }
375 // Some heaps may be in an unparseable state at certain times between
376 // collections. This may be necessary for efficient implementation of
377 // certain allocation-related activities. Calling this function before
378 // attempting to parse a heap ensures that the heap is in a parsable
379 // state (provided other concurrent activity does not introduce
380 // unparsability). It is normally expected, therefore, that this
381 // method is invoked with the world stopped.
382 // NOTE: if you override this method, make sure you call
383 // super::ensure_parsability so that the non-generational
384 // part of the work gets done. See implementation of
385 // CollectedHeap::ensure_parsability and, for instance,
386 // that of GenCollectedHeap::ensure_parsability().
387 // The argument "retire_tlabs" controls whether existing TLABs
388 // are merely filled or also retired, thus preventing further
389 // allocation from them and necessitating allocation of new TLABs.
390 virtual void ensure_parsability(bool retire_tlabs);
392 // Return an estimate of the maximum allocation that could be performed
393 // without triggering any collection or expansion activity. In a
394 // generational collector, for example, this is probably the largest
395 // allocation that could be supported (without expansion) in the youngest
396 // generation. It is "unsafe" because no locks are taken; the result
397 // should be treated as an approximation, not a guarantee, for use in
398 // heuristic resizing decisions.
399 virtual size_t unsafe_max_alloc() = 0;
401 // Section on thread-local allocation buffers (TLABs)
402 // If the heap supports thread-local allocation buffers, it should override
403 // the following methods:
404 // Returns "true" iff the heap supports thread-local allocation buffers.
405 // The default is "no".
406 virtual bool supports_tlab_allocation() const {
407 return false;
408 }
409 // The amount of space available for thread-local allocation buffers.
410 virtual size_t tlab_capacity(Thread *thr) const {
411 guarantee(false, "thread-local allocation buffers not supported");
412 return 0;
413 }
414 // An estimate of the maximum allocation that could be performed
415 // for thread-local allocation buffers without triggering any
416 // collection or expansion activity.
417 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
418 guarantee(false, "thread-local allocation buffers not supported");
419 return 0;
420 }
422 // Can a compiler initialize a new object without store barriers?
423 // This permission only extends from the creation of a new object
424 // via a TLAB up to the first subsequent safepoint. If such permission
425 // is granted for this heap type, the compiler promises to call
426 // defer_store_barrier() below on any slow path allocation of
427 // a new object for which such initializing store barriers will
428 // have been elided.
429 virtual bool can_elide_tlab_store_barriers() const = 0;
431 // If a compiler is eliding store barriers for TLAB-allocated objects,
432 // there is probably a corresponding slow path which can produce
433 // an object allocated anywhere. The compiler's runtime support
434 // promises to call this function on such a slow-path-allocated
435 // object before performing initializations that have elided
436 // store barriers. Returns new_obj, or maybe a safer copy thereof.
437 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);
439 // Answers whether an initializing store to a new object currently
440 // allocated at the given address doesn't need a store
441 // barrier. Returns "true" if it doesn't need an initializing
442 // store barrier; answers "false" if it does.
443 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
445 // If a compiler is eliding store barriers for TLAB-allocated objects,
446 // we will be informed of a slow-path allocation by a call
447 // to new_store_pre_barrier() above. Such a call precedes the
448 // initialization of the object itself, and no post-store-barriers will
449 // be issued. Some heap types require that the barrier strictly follows
450 // the initializing stores. (This is currently implemented by deferring the
451 // barrier until the next slow-path allocation or gc-related safepoint.)
452 // This interface answers whether a particular heap type needs the card
453 // mark to be thus strictly sequenced after the stores.
454 virtual bool card_mark_must_follow_store() const = 0;
456 // If the CollectedHeap was asked to defer a store barrier above,
457 // this informs it to flush such a deferred store barrier to the
458 // remembered set.
459 virtual void flush_deferred_store_barrier(JavaThread* thread);
461 // Does this heap support heap inspection (+PrintClassHistogram?)
462 virtual bool supports_heap_inspection() const = 0;
464 // Perform a collection of the heap; intended for use in implementing
465 // "System.gc". This probably implies as full a collection as the
466 // "CollectedHeap" supports.
467 virtual void collect(GCCause::Cause cause) = 0;
469 // Perform a full collection
470 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
472 // This interface assumes that it's being called by the
473 // vm thread. It collects the heap assuming that the
474 // heap lock is already held and that we are executing in
475 // the context of the vm thread.
476 virtual void collect_as_vm_thread(GCCause::Cause cause);
478 // Callback from VM_CollectForMetadataAllocation operation.
479 MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
480 size_t size,
481 Metaspace::MetadataType mdtype);
483 // Returns the barrier set for this heap
484 BarrierSet* barrier_set() { return _barrier_set; }
486 // Returns "true" iff there is a stop-world GC in progress. (I assume
487 // that it should answer "false" for the concurrent part of a concurrent
488 // collector -- dld).
489 bool is_gc_active() const { return _is_gc_active; }
491 // Total number of GC collections (started)
492 unsigned int total_collections() const { return _total_collections; }
493 unsigned int total_full_collections() const { return _total_full_collections;}
495 // Increment total number of GC collections (started)
496 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
497 void increment_total_collections(bool full = false) {
498 _total_collections++;
499 if (full) {
500 increment_total_full_collections();
501 }
502 }
504 void increment_total_full_collections() { _total_full_collections++; }
506 // Return the AdaptiveSizePolicy for the heap.
507 virtual AdaptiveSizePolicy* size_policy() = 0;
509 // Return the CollectorPolicy for the heap
510 virtual CollectorPolicy* collector_policy() const = 0;
512 void oop_iterate_no_header(OopClosure* cl);
514 // Iterate over all the ref-containing fields of all objects, calling
515 // "cl.do_oop" on each.
516 virtual void oop_iterate(ExtendedOopClosure* cl) = 0;
518 // Iterate over all objects, calling "cl.do_object" on each.
519 virtual void object_iterate(ObjectClosure* cl) = 0;
521 // Similar to object_iterate() except iterates only
522 // over live objects.
523 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
525 // NOTE! There is no requirement that a collector implement these
526 // functions.
527 //
528 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
529 // each address in the (reserved) heap is a member of exactly
530 // one block. The defining characteristic of a block is that it is
531 // possible to find its size, and thus to progress forward to the next
532 // block. (Blocks may be of different sizes.) Thus, blocks may
533 // represent Java objects, or they might be free blocks in a
534 // free-list-based heap (or subheap), as long as the two kinds are
535 // distinguishable and the size of each is determinable.
537 // Returns the address of the start of the "block" that contains the
538 // address "addr". We say "blocks" instead of "object" since some heaps
539 // may not pack objects densely; a chunk may either be an object or a
540 // non-object.
541 virtual HeapWord* block_start(const void* addr) const = 0;
543 // Requires "addr" to be the start of a chunk, and returns its size.
544 // "addr + size" is required to be the start of a new chunk, or the end
545 // of the active area of the heap.
546 virtual size_t block_size(const HeapWord* addr) const = 0;
548 // Requires "addr" to be the start of a block, and returns "TRUE" iff
549 // the block is an object.
550 virtual bool block_is_obj(const HeapWord* addr) const = 0;
552 // Returns the longest time (in ms) that has elapsed since the last
553 // time that any part of the heap was examined by a garbage collection.
554 virtual jlong millis_since_last_gc() = 0;
556 // Perform any cleanup actions necessary before allowing a verification.
557 virtual void prepare_for_verify() = 0;
559 // Generate any dumps preceding or following a full gc
560 void pre_full_gc_dump(GCTimer* timer);
561 void post_full_gc_dump(GCTimer* timer);
563 VirtualSpaceSummary create_heap_space_summary();
564 GCHeapSummary create_heap_summary();
566 MetaspaceSummary create_metaspace_summary();
568 // Print heap information on the given outputStream.
569 virtual void print_on(outputStream* st) const = 0;
570 // The default behavior is to call print_on() on tty.
571 virtual void print() const {
572 print_on(tty);
573 }
574 // Print more detailed heap information on the given
575 // outputStream. The default behavior is to call print_on(). It is
576 // up to each subclass to override it and add any additional output
577 // it needs.
578 virtual void print_extended_on(outputStream* st) const {
579 print_on(st);
580 }
582 virtual void print_on_error(outputStream* st) const {
583 st->print_cr("Heap:");
584 print_extended_on(st);
585 st->cr();
587 _barrier_set->print_on(st);
588 }
590 // Print all GC threads (other than the VM thread)
591 // used by this heap.
592 virtual void print_gc_threads_on(outputStream* st) const = 0;
593 // The default behavior is to call print_gc_threads_on() on tty.
594 void print_gc_threads() {
595 print_gc_threads_on(tty);
596 }
597 // Iterator for all GC threads (other than VM thread)
598 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
600 // Print any relevant tracing info that flags imply.
601 // Default implementation does nothing.
602 virtual void print_tracing_info() const = 0;
604 void print_heap_before_gc();
605 void print_heap_after_gc();
607 // Registering and unregistering an nmethod (compiled code) with the heap.
608 // Override with specific mechanism for each specialized heap type.
609 virtual void register_nmethod(nmethod* nm);
610 virtual void unregister_nmethod(nmethod* nm);
612 void trace_heap_before_gc(GCTracer* gc_tracer);
613 void trace_heap_after_gc(GCTracer* gc_tracer);
615 // Heap verification
616 virtual void verify(bool silent, VerifyOption option) = 0;
618 // Non product verification and debugging.
619 #ifndef PRODUCT
620 // Support for PromotionFailureALot. Return true if it's time to cause a
621 // promotion failure. The no-argument version uses
622 // this->_promotion_failure_alot_count as the counter.
623 inline bool promotion_should_fail(volatile size_t* count);
624 inline bool promotion_should_fail();
626 // Reset the PromotionFailureALot counters. Should be called at the end of a
627 // GC in which promotion failure occurred.
628 inline void reset_promotion_should_fail(volatile size_t* count);
629 inline void reset_promotion_should_fail();
630 #endif // #ifndef PRODUCT
632 #ifdef ASSERT
633 static int fired_fake_oom() {
634 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
635 }
636 #endif
638 public:
639 // This is a convenience method that is used in cases where
640 // the actual number of GC worker threads is not pertinent but
641 // only whether there more than 0. Use of this method helps
642 // reduce the occurrence of ParallelGCThreads to uses where the
643 // actual number may be germane.
644 static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; }
646 /////////////// Unit tests ///////////////
648 NOT_PRODUCT(static void test_is_in();)
649 };
651 // Class to set and reset the GC cause for a CollectedHeap.
653 class GCCauseSetter : StackObj {
654 CollectedHeap* _heap;
655 GCCause::Cause _previous_cause;
656 public:
657 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
658 assert(SafepointSynchronize::is_at_safepoint(),
659 "This method manipulates heap state without locking");
660 _heap = heap;
661 _previous_cause = _heap->gc_cause();
662 _heap->set_gc_cause(cause);
663 }
665 ~GCCauseSetter() {
666 assert(SafepointSynchronize::is_at_safepoint(),
667 "This method manipulates heap state without locking");
668 _heap->set_gc_cause(_previous_cause);
669 }
670 };
672 #endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP