DataWorks离线同步报错Communications link failure，该如何处理？

读取报错问题现象： 读取数据时，报错如下：Communications link failure The last packet successfully received from the server was 7,200,100 milliseconds ago. The last packet sent successfully to the server was 7,200,100 milliseconds ago. - com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure可能原因： 数据库执行SQL查询速度慢，导致MySQL读超时。解决方法：排查是否设置了where过滤条件，以确保筛选字段已添加索引。排查源数据表的数据是否太多。如果数据太多，建议拆分为多个任务。查询日志找到执行阻塞的SQL，咨询数据库管理员解决。写入报错问题现象： 写入数据时，报错如下：Caused by: java.util.concurrent.ExecutionException: ERR-CODE: [TDDL-4614][ERR_EXECUTE_ON_MYSQL] Error occurs when execute on GROUP 'xxx' ATOM 'dockerxxxxx_xxxx_trace_shard_xxxx': Communications link failure The last packet successfully received from the server was 12,672 milliseconds ago. The last packet sent successfully to the server was 12,013 milliseconds ago. More...可能原因： 慢查询导致SocketTimeout。TDDL默认连接数据的SocketTimeout是12秒，如果一个SQL在MySQL端执行超过12秒仍未返回，会报4614的错误。当数据量较大或服务端繁忙时，会偶尔出现该错误。解决方法：建议数据库稳定后，重新运行同步任务。联系数据库管理员调整该超时时间。
https://help.aliyun.com/document_detail/146663.html
，此回答整理自钉群“DataWorks交流群(答疑@机器人)”