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https://issues.apache.org/jira/browse/HDFS-17030?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17729393#comment-17729393
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ASF GitHub Bot commented on HDFS-17030:
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xinglin commented on PR #5700:
URL: https://github.com/apache/hadoop/pull/5700#issuecomment-1577238209
Hi @goiri,
This is Xing from Linkedin's big data storage team (Virajith is my manager).
Simba has approved this PR. After Simba's approval, I just changed the default
value to disable this new feature by default.
If you have more comments, happy to incorporate. Otherwise, would you be
able to merge this PR into trunk? Thanks,
> Limit wait time for getHAServiceState in ObserverReaderProxy
> ------------------------------------------------------------
>
> Key: HDFS-17030
> URL: https://issues.apache.org/jira/browse/HDFS-17030
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs
> Affects Versions: 3.4.0
> Reporter: Xing Lin
> Assignee: Xing Lin
> Priority: Minor
> Labels: pull-request-available
>
> When namenode HA is enabled and a standby NN is not responsible, we have
> observed it would take a long time to serve a request, even though we have a
> healthy observer or active NN.
> Basically, when a standby is down, the RPC client would (re)try to create
> socket connection to that standby for _ipc.client.connect.timeout_ _*
> ipc.client.connect.max.retries.on.timeouts_ before giving up. When we take a
> heap dump at a standby, the NN still accepts the socket connection but it
> won't send responses to these RPC requests and we would timeout after
> _ipc.client.rpc-timeout.ms._ This adds a significantly latency. For clusters
> at Linkedin, we set _ipc.client.rpc-timeout.ms_ to 120 seconds and thus a
> request takes more than 2 mins to complete when we take a heap dump at a
> standby. This has been causing user job failures.
> We could set _ipc.client.rpc-timeout.ms to_ a smaller value when sending
> getHAServiceState requests in ObserverReaderProxy (for user rpc requests, we
> still use the original value from the config). However, that would double the
> socket connection between clients and the NN (which is a deal-breaker).
> The proposal is to add a timeout on getHAServiceState() calls in
> ObserverReaderProxy and we will only wait for the timeout for an NN to
> respond its HA state. Once we pass that timeout, we will move on to probe the
> next NN.
>
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