Mon, 26 Jan 2009 12:47:21 -0800
6786503: Overflow list performance can be improved
Summary: Avoid overflow list walk in CMS & ParNew when it is unnecessary. Fix a couple of correctness issues, including a C-heap leak, in ParNew at the intersection of promotion failure, work queue overflow and object array chunking. Add stress testing option and related assertion checking.
Reviewed-by: jmasa
1 /*
2 * Copyright 1997-2008 Sun Microsystems, Inc. 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.
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
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23 */
25 // The following classes are C++ `closures` for iterating over objects, roots and spaces
27 class ReferenceProcessor;
29 // Closure provides abortability.
31 class Closure : public StackObj {
32 protected:
33 bool _abort;
34 void set_abort() { _abort = true; }
35 public:
36 Closure() : _abort(false) {}
37 // A subtype can use this mechanism to indicate to some iterator mapping
38 // functions that the iteration should cease.
39 bool abort() { return _abort; }
40 void clear_abort() { _abort = false; }
41 };
43 // OopClosure is used for iterating through roots (oop*)
45 class OopClosure : public Closure {
46 public:
47 ReferenceProcessor* _ref_processor;
48 OopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
49 OopClosure() : _ref_processor(NULL) { }
50 virtual void do_oop(oop* o) = 0;
51 virtual void do_oop_v(oop* o) { do_oop(o); }
52 virtual void do_oop(narrowOop* o) = 0;
53 virtual void do_oop_v(narrowOop* o) { do_oop(o); }
55 // In support of post-processing of weak links of KlassKlass objects;
56 // see KlassKlass::oop_oop_iterate().
57 virtual const bool should_remember_klasses() const { return false; }
58 virtual void remember_klass(Klass* k) { /* do nothing */ }
60 // If "true", invoke on nmethods (when scanning compiled frames).
61 virtual const bool do_nmethods() const { return false; }
63 // The methods below control how object iterations invoking this closure
64 // should be performed:
66 // If "true", invoke on header klass field.
67 bool do_header() { return true; } // Note that this is non-virtual.
68 // Controls how prefetching is done for invocations of this closure.
69 Prefetch::style prefetch_style() { // Note that this is non-virtual.
70 return Prefetch::do_none;
71 }
73 // True iff this closure may be safely applied more than once to an oop
74 // location without an intervening "major reset" (like the end of a GC).
75 virtual bool idempotent() { return false; }
76 virtual bool apply_to_weak_ref_discovered_field() { return false; }
77 };
79 // ObjectClosure is used for iterating through an object space
81 class ObjectClosure : public Closure {
82 public:
83 // Called for each object.
84 virtual void do_object(oop obj) = 0;
85 };
88 class BoolObjectClosure : public ObjectClosure {
89 public:
90 virtual bool do_object_b(oop obj) = 0;
91 };
93 // Applies an oop closure to all ref fields in objects iterated over in an
94 // object iteration.
95 class ObjectToOopClosure: public ObjectClosure {
96 OopClosure* _cl;
97 public:
98 void do_object(oop obj);
99 ObjectToOopClosure(OopClosure* cl) : _cl(cl) {}
100 };
102 // A version of ObjectClosure with "memory" (see _previous_address below)
103 class UpwardsObjectClosure: public BoolObjectClosure {
104 HeapWord* _previous_address;
105 public:
106 UpwardsObjectClosure() : _previous_address(NULL) { }
107 void set_previous(HeapWord* addr) { _previous_address = addr; }
108 HeapWord* previous() { return _previous_address; }
109 // A return value of "true" can be used by the caller to decide
110 // if this object's end should *NOT* be recorded in
111 // _previous_address above.
112 virtual bool do_object_bm(oop obj, MemRegion mr) = 0;
113 };
115 // A version of ObjectClosure that is expected to be robust
116 // in the face of possibly uninitialized objects.
117 class ObjectClosureCareful : public ObjectClosure {
118 public:
119 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;
120 virtual size_t do_object_careful(oop p) = 0;
121 };
123 // The following are used in CompactibleFreeListSpace and
124 // ConcurrentMarkSweepGeneration.
126 // Blk closure (abstract class)
127 class BlkClosure : public StackObj {
128 public:
129 virtual size_t do_blk(HeapWord* addr) = 0;
130 };
132 // A version of BlkClosure that is expected to be robust
133 // in the face of possibly uninitialized objects.
134 class BlkClosureCareful : public BlkClosure {
135 public:
136 size_t do_blk(HeapWord* addr) {
137 guarantee(false, "call do_blk_careful instead");
138 return 0;
139 }
140 virtual size_t do_blk_careful(HeapWord* addr) = 0;
141 };
143 // SpaceClosure is used for iterating over spaces
145 class Space;
146 class CompactibleSpace;
148 class SpaceClosure : public StackObj {
149 public:
150 // Called for each space
151 virtual void do_space(Space* s) = 0;
152 };
154 class CompactibleSpaceClosure : public StackObj {
155 public:
156 // Called for each compactible space
157 virtual void do_space(CompactibleSpace* s) = 0;
158 };
162 // MonitorClosure is used for iterating over monitors in the monitors cache
164 class ObjectMonitor;
166 class MonitorClosure : public StackObj {
167 public:
168 // called for each monitor in cache
169 virtual void do_monitor(ObjectMonitor* m) = 0;
170 };
172 // A closure that is applied without any arguments.
173 class VoidClosure : public StackObj {
174 public:
175 // I would have liked to declare this a pure virtual, but that breaks
176 // in mysterious ways, for unknown reasons.
177 virtual void do_void();
178 };
181 // YieldClosure is intended for use by iteration loops
182 // to incrementalize their work, allowing interleaving
183 // of an interruptable task so as to allow other
184 // threads to run (which may not otherwise be able to access
185 // exclusive resources, for instance). Additionally, the
186 // closure also allows for aborting an ongoing iteration
187 // by means of checking the return value from the polling
188 // call.
189 class YieldClosure : public StackObj {
190 public:
191 virtual bool should_return() = 0;
192 };
194 // Abstract closure for serializing data (read or write).
196 class SerializeOopClosure : public OopClosure {
197 public:
198 // Return bool indicating whether closure implements read or write.
199 virtual bool reading() const = 0;
201 // Read/write the int pointed to by i.
202 virtual void do_int(int* i) = 0;
204 // Read/write the size_t pointed to by i.
205 virtual void do_size_t(size_t* i) = 0;
207 // Read/write the void pointer pointed to by p.
208 virtual void do_ptr(void** p) = 0;
210 // Read/write the HeapWord pointer pointed to be p.
211 virtual void do_ptr(HeapWord** p) = 0;
213 // Read/write the region specified.
214 virtual void do_region(u_char* start, size_t size) = 0;
216 // Check/write the tag. If reading, then compare the tag against
217 // the passed in value and fail is they don't match. This allows
218 // for verification that sections of the serialized data are of the
219 // correct length.
220 virtual void do_tag(int tag) = 0;
221 };