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https://issues.apache.org/jira/browse/HDFS-4849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13705246#comment-13705246
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Suresh Srinivas commented on HDFS-4849:
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Konstantin, I will take a look at the patch shortly.
In Hadoop summit we agreed that this change will not make create idempotent.
You are only enabling retry from a single client. So please consider updating
the jira description accordingly. The patch also has the word idempotent used
instead of retry. How did you solve the issue of two threads in a single client
calling create?
Please see my analysis of namenode operations in HDFS-4974. There are 12
operations that are non-idempotent. I feel we should use retry cache instead of
doing a separate retry support for create alone. I will post a n early patch
for you to look at. I do not believe there is any performance or simpler code
advantage to doing create retry support in a different way. Others, please
chime in.
> Idempotent create and append operations.
> ----------------------------------------
>
> Key: HDFS-4849
> URL: https://issues.apache.org/jira/browse/HDFS-4849
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 2.0.4-alpha
> Reporter: Konstantin Shvachko
> Assignee: Konstantin Shvachko
> Priority: Blocker
> Attachments: idempotentCreate-branch2.patch, idempotentCreate.patch,
> idempotentCreate.patch, idempotentCreate.patch, idempotentCreate.patch
>
>
> create, append and delete operations can be made idempotent. This will reduce
> chances for a job or other app failures when NN fails over.
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