Thu, 04 Oct 2012 10:40:23 -0700
7198873: NPG: VM Does not unload classes with UseConcMarkSweepGC
Reviewed-by: johnc, mgerdin, jwilhelm
1 /*
2 * Copyright (c) 1997, 2012, 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_IMPLEMENTATION_SHARED_MARKSWEEP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP
28 #include "gc_interface/collectedHeap.hpp"
29 #include "memory/universe.hpp"
30 #include "oops/markOop.hpp"
31 #include "oops/oop.hpp"
32 #include "runtime/timer.hpp"
33 #include "utilities/growableArray.hpp"
34 #include "utilities/stack.hpp"
35 #include "utilities/taskqueue.hpp"
37 class ReferenceProcessor;
38 class DataLayout;
40 // MarkSweep takes care of global mark-compact garbage collection for a
41 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All
42 // generations are assumed to support marking; those that can also support
43 // compaction.
44 //
45 // Class unloading will only occur when a full gc is invoked.
47 // If VALIDATE_MARK_SWEEP is defined, the -XX:+ValidateMarkSweep flag will
48 // be operational, and will provide slow but comprehensive self-checks within
49 // the GC. This is not enabled by default in product or release builds,
50 // since the extra call to track_adjusted_pointer() in _adjust_pointer()
51 // would be too much overhead, and would disturb performance measurement.
52 // However, debug builds are sometimes way too slow to run GC tests!
53 #ifdef ASSERT
54 #define VALIDATE_MARK_SWEEP 1
55 #endif
56 #ifdef VALIDATE_MARK_SWEEP
57 #define VALIDATE_MARK_SWEEP_ONLY(code) code
58 #else
59 #define VALIDATE_MARK_SWEEP_ONLY(code)
60 #endif
62 // declared at end
63 class PreservedMark;
65 class MarkSweep : AllStatic {
66 //
67 // Inline closure decls
68 //
69 class FollowRootClosure: public OopsInGenClosure {
70 public:
71 virtual void do_oop(oop* p);
72 virtual void do_oop(narrowOop* p);
73 };
75 class MarkAndPushClosure: public OopClosure {
76 public:
77 virtual void do_oop(oop* p);
78 virtual void do_oop(narrowOop* p);
79 };
81 // The one and only place to start following the classes.
82 // Should only be applied to the ClassLoaderData klasses list.
83 class FollowKlassClosure : public KlassClosure {
84 public:
85 void do_klass(Klass* klass);
86 };
87 class AdjustKlassClosure : public KlassClosure {
88 public:
89 void do_klass(Klass* klass);
90 };
92 class FollowStackClosure: public VoidClosure {
93 public:
94 virtual void do_void();
95 };
97 class AdjustPointerClosure: public OopsInGenClosure {
98 private:
99 bool _is_root;
100 public:
101 AdjustPointerClosure(bool is_root) : _is_root(is_root) {}
102 virtual void do_oop(oop* p);
103 virtual void do_oop(narrowOop* p);
104 };
106 // Used for java/lang/ref handling
107 class IsAliveClosure: public BoolObjectClosure {
108 public:
109 virtual void do_object(oop p);
110 virtual bool do_object_b(oop p);
111 };
113 class KeepAliveClosure: public OopClosure {
114 protected:
115 template <class T> void do_oop_work(T* p);
116 public:
117 virtual void do_oop(oop* p);
118 virtual void do_oop(narrowOop* p);
119 };
121 //
122 // Friend decls
123 //
124 friend class AdjustPointerClosure;
125 friend class KeepAliveClosure;
126 friend class VM_MarkSweep;
127 friend void marksweep_init();
129 //
130 // Vars
131 //
132 protected:
133 // Total invocations of a MarkSweep collection
134 static unsigned int _total_invocations;
136 // Traversal stacks used during phase1
137 static Stack<oop, mtGC> _marking_stack;
138 static Stack<ObjArrayTask, mtGC> _objarray_stack;
140 // Space for storing/restoring mark word
141 static Stack<markOop, mtGC> _preserved_mark_stack;
142 static Stack<oop, mtGC> _preserved_oop_stack;
143 static size_t _preserved_count;
144 static size_t _preserved_count_max;
145 static PreservedMark* _preserved_marks;
147 // Reference processing (used in ...follow_contents)
148 static ReferenceProcessor* _ref_processor;
150 #ifdef VALIDATE_MARK_SWEEP
151 static GrowableArray<void*>* _root_refs_stack;
152 static GrowableArray<oop> * _live_oops;
153 static GrowableArray<oop> * _live_oops_moved_to;
154 static GrowableArray<size_t>* _live_oops_size;
155 static size_t _live_oops_index;
156 static size_t _live_oops_index_at_perm;
157 static GrowableArray<void*>* _other_refs_stack;
158 static GrowableArray<void*>* _adjusted_pointers;
159 static bool _pointer_tracking;
160 static bool _root_tracking;
162 // The following arrays are saved since the time of the last GC and
163 // assist in tracking down problems where someone has done an errant
164 // store into the heap, usually to an oop that wasn't properly
165 // handleized across a GC. If we crash or otherwise fail before the
166 // next GC, we can query these arrays to find out the object we had
167 // intended to do the store to (assuming it is still alive) and the
168 // offset within that object. Covered under RecordMarkSweepCompaction.
169 static GrowableArray<HeapWord*> * _cur_gc_live_oops;
170 static GrowableArray<HeapWord*> * _cur_gc_live_oops_moved_to;
171 static GrowableArray<size_t>* _cur_gc_live_oops_size;
172 static GrowableArray<HeapWord*> * _last_gc_live_oops;
173 static GrowableArray<HeapWord*> * _last_gc_live_oops_moved_to;
174 static GrowableArray<size_t>* _last_gc_live_oops_size;
175 #endif
177 // Non public closures
178 static KeepAliveClosure keep_alive;
180 // Debugging
181 static void trace(const char* msg) PRODUCT_RETURN;
183 public:
184 // Public closures
185 static IsAliveClosure is_alive;
186 static FollowRootClosure follow_root_closure;
187 static CodeBlobToOopClosure follow_code_root_closure; // => follow_root_closure
188 static MarkAndPushClosure mark_and_push_closure;
189 static FollowKlassClosure follow_klass_closure;
190 static FollowStackClosure follow_stack_closure;
191 static AdjustPointerClosure adjust_root_pointer_closure;
192 static AdjustPointerClosure adjust_pointer_closure;
193 static AdjustKlassClosure adjust_klass_closure;
195 // Accessors
196 static unsigned int total_invocations() { return _total_invocations; }
198 // Reference Processing
199 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
201 // Call backs for marking
202 static void mark_object(oop obj);
203 // Mark pointer and follow contents. Empty marking stack afterwards.
204 template <class T> static inline void follow_root(T* p);
206 // Check mark and maybe push on marking stack
207 template <class T> static void mark_and_push(T* p);
209 static inline void push_objarray(oop obj, size_t index);
211 static void follow_stack(); // Empty marking stack.
213 static void follow_klass(Klass* klass);
214 static void adjust_klass(Klass* klass);
216 static void follow_class_loader(ClassLoaderData* cld);
217 static void adjust_class_loader(ClassLoaderData* cld);
219 static void preserve_mark(oop p, markOop mark);
220 // Save the mark word so it can be restored later
221 static void adjust_marks(); // Adjust the pointers in the preserved marks table
222 static void restore_marks(); // Restore the marks that we saved in preserve_mark
224 template <class T> static inline void adjust_pointer(T* p, bool isroot);
226 static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); }
227 static void adjust_pointer(oop* p) { adjust_pointer(p, false); }
228 static void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); }
230 #ifdef VALIDATE_MARK_SWEEP
231 static void track_adjusted_pointer(void* p, bool isroot);
232 static void check_adjust_pointer(void* p);
233 static void track_interior_pointers(oop obj);
234 static void check_interior_pointers();
236 static void reset_live_oop_tracking();
237 static void register_live_oop(oop p, size_t size);
238 static void validate_live_oop(oop p, size_t size);
239 static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top);
240 static void compaction_complete();
242 // Querying operation of RecordMarkSweepCompaction results.
243 // Finds and prints the current base oop and offset for a word
244 // within an oop that was live during the last GC. Helpful for
245 // tracking down heap stomps.
246 static void print_new_location_of_heap_address(HeapWord* q);
247 #endif
248 };
250 class PreservedMark VALUE_OBJ_CLASS_SPEC {
251 private:
252 oop _obj;
253 markOop _mark;
255 public:
256 void init(oop obj, markOop mark) {
257 _obj = obj;
258 _mark = mark;
259 }
261 void adjust_pointer() {
262 MarkSweep::adjust_pointer(&_obj);
263 }
265 void restore() {
266 _obj->set_mark(_mark);
267 }
268 };
270 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP