diff -r 8624da129f0b -r 8b46c4d82093 src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp
--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Mon Aug 31 05:27:29 2009 -0700
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Wed Sep 02 00:04:29 2009 -0700
@@ -901,7 +901,8 @@
   static void marking_phase(ParCompactionManager* cm,
                             bool maximum_heap_compaction);
   static void follow_stack(ParCompactionManager* cm);
-  static void follow_weak_klass_links(ParCompactionManager* cm);
+  static void follow_weak_klass_links();
+  static void follow_mdo_weak_refs();
 
   template <class T> static inline void adjust_pointer(T* p, bool is_root);
   static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); }
@@ -1221,6 +1222,9 @@
   // Update subklass/sibling/implementor links at end of marking.
   static void revisit_weak_klass_link(ParCompactionManager* cm, Klass* k);
 
+  // Clear unmarked oops in MDOs at the end of marking.
+  static void revisit_mdo(ParCompactionManager* cm, DataLayout* p);
+
 #ifndef PRODUCT
   // Debugging support.
   static const char* space_names[last_space_id];