Mon, 07 Jul 2014 10:12:40 +0200
8049421: G1 Class Unloading after completing a concurrent mark cycle
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
Contributed-by: stefan.karlsson@oracle.com, mikael.gerdin@oracle.com
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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
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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;
39 class SerialOldTracer;
40 class STWGCTimer;
42 // MarkSweep takes care of global mark-compact garbage collection for a
43 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All
44 // generations are assumed to support marking; those that can also support
45 // compaction.
46 //
47 // Class unloading will only occur when a full gc is invoked.
49 // declared at end
50 class PreservedMark;
52 class MarkSweep : AllStatic {
53 //
54 // Inline closure decls
55 //
56 class FollowRootClosure: public OopsInGenClosure {
57 public:
58 virtual void do_oop(oop* p);
59 virtual void do_oop(narrowOop* p);
60 };
62 class MarkAndPushClosure: public OopClosure {
63 public:
64 virtual void do_oop(oop* p);
65 virtual void do_oop(narrowOop* p);
66 };
68 class FollowStackClosure: public VoidClosure {
69 public:
70 virtual void do_void();
71 };
73 class AdjustPointerClosure: public OopsInGenClosure {
74 public:
75 virtual void do_oop(oop* p);
76 virtual void do_oop(narrowOop* p);
77 };
79 // Used for java/lang/ref handling
80 class IsAliveClosure: public BoolObjectClosure {
81 public:
82 virtual bool do_object_b(oop p);
83 };
85 class KeepAliveClosure: public OopClosure {
86 protected:
87 template <class T> void do_oop_work(T* p);
88 public:
89 virtual void do_oop(oop* p);
90 virtual void do_oop(narrowOop* p);
91 };
93 //
94 // Friend decls
95 //
96 friend class AdjustPointerClosure;
97 friend class KeepAliveClosure;
98 friend class VM_MarkSweep;
99 friend void marksweep_init();
101 //
102 // Vars
103 //
104 protected:
105 // Total invocations of a MarkSweep collection
106 static uint _total_invocations;
108 // Traversal stacks used during phase1
109 static Stack<oop, mtGC> _marking_stack;
110 static Stack<ObjArrayTask, mtGC> _objarray_stack;
112 // Space for storing/restoring mark word
113 static Stack<markOop, mtGC> _preserved_mark_stack;
114 static Stack<oop, mtGC> _preserved_oop_stack;
115 static size_t _preserved_count;
116 static size_t _preserved_count_max;
117 static PreservedMark* _preserved_marks;
119 // Reference processing (used in ...follow_contents)
120 static ReferenceProcessor* _ref_processor;
122 static STWGCTimer* _gc_timer;
123 static SerialOldTracer* _gc_tracer;
125 // Non public closures
126 static KeepAliveClosure keep_alive;
128 // Debugging
129 static void trace(const char* msg) PRODUCT_RETURN;
131 public:
132 // Public closures
133 static IsAliveClosure is_alive;
134 static FollowRootClosure follow_root_closure;
135 static MarkAndPushClosure mark_and_push_closure;
136 static FollowStackClosure follow_stack_closure;
137 static CLDToOopClosure follow_cld_closure;
138 static AdjustPointerClosure adjust_pointer_closure;
139 static CLDToOopClosure adjust_cld_closure;
141 // Accessors
142 static uint total_invocations() { return _total_invocations; }
144 // Reference Processing
145 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
147 static STWGCTimer* gc_timer() { return _gc_timer; }
148 static SerialOldTracer* gc_tracer() { return _gc_tracer; }
150 // Call backs for marking
151 static void mark_object(oop obj);
152 // Mark pointer and follow contents. Empty marking stack afterwards.
153 template <class T> static inline void follow_root(T* p);
155 // Check mark and maybe push on marking stack
156 template <class T> static void mark_and_push(T* p);
158 static inline void push_objarray(oop obj, size_t index);
160 static void follow_stack(); // Empty marking stack.
162 static void follow_klass(Klass* klass);
164 static void follow_class_loader(ClassLoaderData* cld);
166 static void preserve_mark(oop p, markOop mark);
167 // Save the mark word so it can be restored later
168 static void adjust_marks(); // Adjust the pointers in the preserved marks table
169 static void restore_marks(); // Restore the marks that we saved in preserve_mark
171 template <class T> static inline void adjust_pointer(T* p);
172 };
174 class PreservedMark VALUE_OBJ_CLASS_SPEC {
175 private:
176 oop _obj;
177 markOop _mark;
179 public:
180 void init(oop obj, markOop mark) {
181 _obj = obj;
182 _mark = mark;
183 }
185 void adjust_pointer() {
186 MarkSweep::adjust_pointer(&_obj);
187 }
189 void restore() {
190 _obj->set_mark(_mark);
191 }
192 };
194 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP