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https://issues.apache.org/jira/browse/HDFS-4942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13698674#comment-13698674
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Bikas Saha commented on HDFS-4942:
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Some clarifications would be good
1) User runs create command using CLI. Internally, the command is tried many
times over RPC. Will these retries have the same UUID and will result in
response coming from retry cache? I think yes.
2) Client in 1) above tries many times and fails. User retries the CLI command
again. This will generate a new set of retries. Will these have the same UUID
as the retries in 1) above. Will they get response from retry cache?
> Add retry cache support in Namenode
> -----------------------------------
>
> Key: HDFS-4942
> URL: https://issues.apache.org/jira/browse/HDFS-4942
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: ha, namenode
> Reporter: Suresh Srinivas
> Assignee: Suresh Srinivas
> Attachments: HDFSRetryCache.pdf
>
>
> In current HA mechanism with FailoverProxyProvider and non HA setups with
> RetryProxy retry a request from the RPC layer. If the retried request has
> already been processed at the namenode, the subsequent attempts fail for
> non-idempotent operations such as create, append, delete, rename etc. This
> will cause application failures during HA failover, network issues etc.
> This jira proposes adding retry cache at the namenode to handle these
> failures. More details in the comments.
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