calls++;
    public Object execute (String method, Vector params) throws XmlRpcException, IOException {    	Worker worker = getWorker ();	long start = System.currentTimeMillis ();	try {    	    Object retval =  worker.execute (method, params);	    long end = System.currentTimeMillis ();	    calls++;	    roundtrip = (int) ((roundtrip*4)+(end-start))/5;	    return retval;	} finally {	    releaseWorker (worker);	}    }