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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-1965) IPCs done using block token-based tickets can't reuse connections
Date Sat, 21 May 2011 00:51:47 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13037214#comment-13037214
] 

Tsz Wo (Nicholas), SZE commented on HDFS-1965:
----------------------------------------------

Hey Todd, please wait for Hadoop QA before committing the patch.  It sometimes catches unexpected
problems.

> IPCs done using block token-based tickets can't reuse connections
> -----------------------------------------------------------------
>
>                 Key: HDFS-1965
>                 URL: https://issues.apache.org/jira/browse/HDFS-1965
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: security
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>            Priority: Critical
>             Fix For: 0.22.0
>
>         Attachments: hdfs-1965-0.22.txt, hdfs-1965.txt, hdfs-1965.txt, hdfs-1965.txt
>
>
> This is the reason that TestFileConcurrentReaders has been failing a lot. Reproducing
a comment from HDFS-1057:
> The test has a thread which continually re-opens the file which is being written to.
Since the file's in the middle of being written, it makes an RPC to the DataNode in order
to determine the visible length of the file. This RPC is authenticated using the block token
which came back in the LocatedBlocks object as the security ticket.
> When this RPC hits the IPC layer, it looks at its existing connections and sees none
that can be re-used, since the block token differs between the two requesters. Hence, it reconnects,
and we end up with hundreds or thousands of IPC connections to the datanode.

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