public static int default_tp_keepalive_time() {
        return getInt(Configs.TP_KEEPALIVE_TIME, Configs.TP_KEEPALIVE_TIME_DEFAULT);
    }
get configs through system properties prior to default value

@author tsui
@version $Id: ConfigManager.java, v 0.1 2017-08-03 19:21 tsui Exp $
src/main/java/com/alipay/remoting/config/ConfigManager.java