Sat, 01 Sep 2012 13:25:18 -0400
6964458: Reimplement class meta-data storage to use native memory
Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes
Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland
Contributed-by: jmasa <jon.masamitsu@oracle.com>, stefank <stefan.karlsson@oracle.com>, mgerdin <mikael.gerdin@oracle.com>, never <tom.rodriguez@oracle.com>
1 /*
2 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSTASKS_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSTASKS_HPP
28 #include "memory/allocation.hpp"
29 #include "utilities/growableArray.hpp"
31 //
32 // psTasks.hpp is a collection of GCTasks used by the
33 // parallelScavenge collector.
34 //
36 class GCTask;
37 class OopClosure;
38 class OopStack;
39 class ObjectStartArray;
40 class ParallelTaskTerminator;
41 class MutableSpace;
42 class PSOldGen;
43 class Thread;
44 class VMThread;
46 //
47 // ScavengeRootsTask
48 //
49 // This task scans all the roots of a given type.
50 //
51 //
53 class ScavengeRootsTask : public GCTask {
54 public:
55 enum RootType {
56 universe = 1,
57 jni_handles = 2,
58 threads = 3,
59 object_synchronizer = 4,
60 flat_profiler = 5,
61 system_dictionary = 6,
62 management = 7,
63 jvmti = 8,
64 code_cache = 9
65 };
66 private:
67 RootType _root_type;
68 public:
69 ScavengeRootsTask(RootType value) : _root_type(value) {}
71 char* name() { return (char *)"scavenge-roots-task"; }
73 virtual void do_it(GCTaskManager* manager, uint which);
74 };
76 //
77 // ThreadRootsTask
78 //
79 // This task scans the roots of a single thread. This task
80 // enables scanning of thread roots in parallel.
81 //
83 class ThreadRootsTask : public GCTask {
84 private:
85 JavaThread* _java_thread;
86 VMThread* _vm_thread;
87 public:
88 ThreadRootsTask(JavaThread* root) : _java_thread(root), _vm_thread(NULL) {}
89 ThreadRootsTask(VMThread* root) : _java_thread(NULL), _vm_thread(root) {}
91 char* name() { return (char *)"thread-roots-task"; }
93 virtual void do_it(GCTaskManager* manager, uint which);
94 };
96 //
97 // StealTask
98 //
99 // This task is used to distribute work to idle threads.
100 //
102 class StealTask : public GCTask {
103 private:
104 ParallelTaskTerminator* const _terminator;
105 public:
106 char* name() { return (char *)"steal-task"; }
108 StealTask(ParallelTaskTerminator* t);
110 ParallelTaskTerminator* terminator() { return _terminator; }
112 virtual void do_it(GCTaskManager* manager, uint which);
113 };
115 //
116 // SerialOldToYoungRootsTask
117 //
118 // This task is used to scan for roots in the perm gen
120 class SerialOldToYoungRootsTask : public GCTask {
121 private:
122 PSOldGen* _gen;
123 HeapWord* _gen_top;
125 public:
126 SerialOldToYoungRootsTask(PSOldGen *gen, HeapWord* gen_top) :
127 _gen(gen), _gen_top(gen_top) { }
129 char* name() { return (char *)"serial-old-to-young-roots-task"; }
131 virtual void do_it(GCTaskManager* manager, uint which);
132 };
134 //
135 // OldToYoungRootsTask
136 //
137 // This task is used to scan old to young roots in parallel
138 //
139 // A GC thread executing this tasks divides the generation (old gen)
140 // into slices and takes a stripe in the slice as its part of the
141 // work.
142 //
143 // +===============+ slice 0
144 // | stripe 0 |
145 // +---------------+
146 // | stripe 1 |
147 // +---------------+
148 // | stripe 2 |
149 // +---------------+
150 // | stripe 3 |
151 // +===============+ slice 1
152 // | stripe 0 |
153 // +---------------+
154 // | stripe 1 |
155 // +---------------+
156 // | stripe 2 |
157 // +---------------+
158 // | stripe 3 |
159 // +===============+ slice 2
160 // ...
161 //
162 // A task is created for each stripe. In this case there are 4 tasks
163 // created. A GC thread first works on its stripe within slice 0
164 // and then moves to its stripe in the next slice until all stripes
165 // exceed the top of the generation. Note that having fewer GC threads
166 // than stripes works because all the tasks are executed so all stripes
167 // will be covered. In this example if 4 tasks have been created to cover
168 // all the stripes and there are only 3 threads, one of the threads will
169 // get the tasks with the 4th stripe. However, there is a dependence in
170 // CardTableExtension::scavenge_contents_parallel() on the number
171 // of tasks created. In scavenge_contents_parallel the distance
172 // to the next stripe is calculated based on the number of tasks.
173 // If the stripe width is ssize, a task's next stripe is at
174 // ssize * number_of_tasks (= slice_stride). In this case after
175 // finishing stripe 0 in slice 0, the thread finds the stripe 0 in slice1
176 // by adding slice_stride to the start of stripe 0 in slice 0 to get
177 // to the start of stride 0 in slice 1.
179 class OldToYoungRootsTask : public GCTask {
180 private:
181 PSOldGen* _gen;
182 HeapWord* _gen_top;
183 uint _stripe_number;
184 uint _stripe_total;
186 public:
187 OldToYoungRootsTask(PSOldGen *gen,
188 HeapWord* gen_top,
189 uint stripe_number,
190 uint stripe_total) :
191 _gen(gen),
192 _gen_top(gen_top),
193 _stripe_number(stripe_number),
194 _stripe_total(stripe_total) { }
196 char* name() { return (char *)"old-to-young-roots-task"; }
198 virtual void do_it(GCTaskManager* manager, uint which);
199 };
201 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSTASKS_HPP