--- old/src/share/vm/runtime/thread.cpp	Tue Feb 26 15:23:14 2013
+++ new/src/share/vm/runtime/thread.cpp	Tue Feb 26 15:23:14 2013
@@ -4285,7 +4285,9 @@
       if (owner == (address)p) return p;
     }
   }
-  assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
+  // Cannot assert on lack of success here since this function may be
+  // used by code that is trying to report useful problem information
+  // like deadlock detection.
   if (UseHeavyMonitors) return NULL;
 
   //
@@ -4303,7 +4305,7 @@
       }
     }
   }
-  assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
+  // cannot assert on lack of success here; see above comment
   return the_owner;
 }