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He Tianyi commented on HDFS-9665: --------------------------------- 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? -- This message was sent by Atlassian JIRA (v6.3.4#6332)