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https://issues.apache.org/jira/browse/HDFS-9665?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15107854#comment-15107854
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He Tianyi commented on HDFS-9665:
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Also, I observed that {{doTailEdits}} may acquire write lock in standby
namenode and last several seconds in my cluster.
This causes first request from client to block either.
> Cilents are easily affected by standby namenode
> -----------------------------------------------
>
> Key: HDFS-9665
> URL: https://issues.apache.org/jira/browse/HDFS-9665
> Project: Hadoop HDFS
> Issue Type: Wish
> Components: hdfs-client, namenode
> Affects Versions: 2.6.0
> Reporter: He Tianyi
> Assignee: He Tianyi
> Priority: Minor
>
> My case is during restarting of standby NameNode, there is chances that
> {{hadoop fs}} command get hung until either IPC timeout reached or
> {{StandbyException}} received, and then failover to active NameNode.
> Normally, duration of the 'hung stage' depends on
> {{min(timeout_configuration, rpc_queue_time)}}. However, RPC queue in standby
> NameNode is usually filled with block reports at this period, client requests
> can't get processed quickly.
> I wish to get rid of this, by one of the following manners:
> a) we distinguish priority in RPC queue (chances causing starvation)
> b) we speculate first request, send it to both NameNodes, and take one valid
> response.
> c) make client aware of HA state (by accessing ZK probably, chances causing
> performance issue)
> Any suggestions or comments?
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