diff -r f2365fbd62f4 -r 2e86734ba620 hotspot/src/share/vm/runtime/thread.hpp
--- a/hotspot/src/share/vm/runtime/thread.hpp	Mon May 16 14:21:16 2011 -0700
+++ b/hotspot/src/share/vm/runtime/thread.hpp	Mon May 16 22:16:44 2011 -0700
@@ -439,7 +439,7 @@
   // GC support
   // Apply "f->do_oop" to all root oops in "this".
   // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
-  void oops_do(OopClosure* f, CodeBlobClosure* cf);
+  virtual void oops_do(OopClosure* f, CodeBlobClosure* cf);
 
   // Handles the parallel case for the method below.
 private:
@@ -1381,7 +1381,7 @@
   void trace_frames()                            PRODUCT_RETURN;
 
   // Print an annotated view of the stack frames
-  void print_frame_layout(int depth = 0, bool validate_only = false) PRODUCT_RETURN;
+  void print_frame_layout(int depth = 0, bool validate_only = false) NOT_DEBUG_RETURN;
   void validate_frame_layout() {
     print_frame_layout(0, true);
   }
@@ -1698,6 +1698,8 @@
   CompileQueue* _queue;
   BufferBlob*   _buffer_blob;
 
+  nmethod*      _scanned_nmethod;  // nmethod being scanned by the sweeper
+
  public:
 
   static CompilerThread* current();
@@ -1726,6 +1728,11 @@
     _log = log;
   }
 
+  // GC support
+  // Apply "f->do_oop" to all root oops in "this".
+  // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
+  void oops_do(OopClosure* f, CodeBlobClosure* cf);
+
 #ifndef PRODUCT
 private:
   IdealGraphPrinter *_ideal_graph_printer;
@@ -1737,6 +1744,12 @@
   // Get/set the thread's current task
   CompileTask*  task()                           { return _task; }
   void          set_task(CompileTask* task)      { _task = task; }
+
+  // Track the nmethod currently being scanned by the sweeper
+  void          set_scanned_nmethod(nmethod* nm) {
+    assert(_scanned_nmethod == NULL || nm == NULL, "should reset to NULL before writing a new value");
+    _scanned_nmethod = nm;
+  }
 };
 
 inline CompilerThread* CompilerThread::current() {