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https://issues.apache.org/jira/browse/HDFS-14134?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16834936#comment-16834936
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Lukas Majercak commented on HDFS-14134:
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Hi [~John Smith]. I'm not sure if it's that simple.
Say you have 2 NNs, where nn1 is active, nn2 is standby. If your current
target is nn2, but we send a request to both, you can get responses like:
nn1 - RETRY
nn2 - RETRY_AND_FAILOVER
In this case, the ideal scenario would be to failover to nn1, but what you're
proposing would not do that.
I think this obviously has room for improvement, as in some cases RETRY >
FAILOVER is reasonable, but I'd like to refrain from increasing the scope of
this JIRA. Maybe we can create a new one and have the discussion there?
> Idempotent operations throwing RemoteException should not be retried by the
> client
> ----------------------------------------------------------------------------------
>
> Key: HDFS-14134
> URL: https://issues.apache.org/jira/browse/HDFS-14134
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs, hdfs-client, ipc
> Reporter: Lukas Majercak
> Assignee: Lukas Majercak
> Priority: Critical
> Attachments: HDFS-14134.001.patch, HDFS-14134.002.patch,
> HDFS-14134.003.patch, HDFS-14134.004.patch, HDFS-14134.005.patch,
> HDFS-14134.006.patch, HDFS-14134.007.patch,
> HDFS-14134_retrypolicy_change_proposal.pdf,
> HDFS-14134_retrypolicy_change_proposal_1.pdf
>
>
> Currently, some operations that throw IOException on the NameNode are
> evaluated by RetryPolicy as FAILOVER_AND_RETRY, but they should just fail
> fast.
> For example, when calling getXAttr("user.some_attr", file") where the file
> does not have the attribute, NN throws an IOException with message "could not
> find attr". The current client retry policy determines the action for that to
> be FAILOVER_AND_RETRY. The client then fails over and retries until it
> reaches the maximum number of retries. Supposedly, the client should be able
> to tell that this exception is normal and fail fast.
> Moreover, even if the action was FAIL, the RetryInvocationHandler looks at
> all the retry actions from all requests, and FAILOVER_AND_RETRY takes
> precedence over FAIL action.
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