怎么获取dataset中元素数量？

val inputMysql: DataSet[Row] = env.createInput(JDBCInputFormat.buildJDBCInputFormat()
      .setDrivername(addressProperties.mysqlDriver)
      .setDBUrl(addressProperties.mysqlConnect)
      .setUsername(addressProperties.mysqlUserName)
      .setPassword(addressProperties.mysqlPassWord)
      .setQuery("select TERMINAL_ID from TM_ALARM_EVENT where STATUS = '0' and TERMINAL_ID = '" + terminalID + "' and LEVEL = '3' and TYPE = '2'")
      .setRowTypeInfo(new RowTypeInfo(BasicTypeInfo.STRING_TYPE_INFO))
      .finish()
    )
    inputMysql.count()

直接调用count()方法放到flink集群上运行的时候会报错，java.lang.Exception: Could not create actor system，不知道怎么解，求帮助

env.excute 执行任务？