申请了大数据中心资源后，拟定使用计算引擎：spark。首先，使用spark读取hdfs数据，出现错误：
- DFSClient: Failed to connect to /192.168.137.2:50010 for block, add to deadNodes and continue. java.net.ConnectException: Connection timed out: no further information java.net.ConnectException: Connection timed out: no further information
