Re: synchronized block question...

Lastly, consider locking on some object you already have, rather than
making a special object to lock on. I think synchronizing on the class
object is the same as synchronizing on a static object, and much harder
to mess up. (Joshua did mention class literals too, now that I look.)

public class ProcessData extends org.apache.struts.action.Action {

    public ActionForward execute(ActionMapping mapping, ActionForm
form,
            HttpServletRequest request, HttpServletResponse response)
            throws Exception {

        // ...some code...
        synchronized ( ProcessData.class )
        {
          // ...more code...
        }
        //...more code...

    }
}