marking the coordinator rack null) dead for group

flink 日志marking the coordinator rack null) dead for group
问题:
flink拉取日志之后，处理时间过长，导致kafka-client session超时
解决：

    prop.setProperty("session.timeout.ms", "60000") 默认10*1000 ms
    prop.setProperty("fetch.max.wait.ms", "5000") 默认500ms

参考
https://www.cnblogs.com/Springmoon-venn/p/13405140.html
https://www.freesion.com/article/1169969839/