Index: generic/nsf.c
===================================================================
diff -u -r6cb02ec6ee2b0bd8857ab9deda0dd6eff7265af5 -rb36a57bbc5ab0ff8361293a4e73c7ac5b4da4b2d
--- generic/nsf.c	(.../nsf.c)	(revision 6cb02ec6ee2b0bd8857ab9deda0dd6eff7265af5)
+++ generic/nsf.c	(.../nsf.c)	(revision b36a57bbc5ab0ff8361293a4e73c7ac5b4da4b2d)
@@ -25070,7 +25070,7 @@
   }
 #endif
 
-  /*fprintf(stderr, "+++ call tcl-defined exit handler\n");*/
+    fprintf(stderr, "+++ call tcl-defined exit handler (%lx)\n", pthread_self());
 
   /*
    * Evaluate user-defined exit handler.