public static double getLeastWindowExceptionRateMultiple(String appName) {
        FaultToleranceConfig config = getConfig(appName);
        return config.getLeastWindowExceptionRateMultiple();
    }
Gets least window exception rate multiple.

@param appName the app name
@return the least window exception rate multiple
fault/fault-tolerance/src/main/java/com/alipay/sofa/rpc/client/aft/FaultToleranceConfigManager.java