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https://issues.apache.org/jira/browse/HDFS-7597?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14535079#comment-14535079
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Hadoop QA commented on HDFS-7597:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:red}-1{color} | patch |   0m  0s | The patch command could not apply 
the patch during dryrun. |
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|| Subsystem || Report/Notes ||
| Patch URL | 
http://issues.apache.org/jira/secure/attachment/12692601/HDFS-7597.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / 3cefc02 |
| Console output | 
https://builds.apache.org/job/PreCommit-HDFS-Build/10876/console |


This message was automatically generated.

> DNs should not open new NN connections when webhdfs clients seek
> ----------------------------------------------------------------
>
>                 Key: HDFS-7597
>                 URL: https://issues.apache.org/jira/browse/HDFS-7597
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: webhdfs
>    Affects Versions: 2.0.0-alpha
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>            Priority: Critical
>              Labels: BB2015-05-TBR
>         Attachments: HDFS-7597.patch, HDFS-7597.patch
>
>
> Webhdfs seeks involve closing the current connection, and reissuing a new 
> open request with the new offset.  The RPC layer caches connections so the DN 
> keeps a lingering connection open to the NN.  Connection caching is in part 
> based on UGI.  Although the client used the same token for the new offset 
> request, the UGI is different which forces the DN to open another unnecessary 
> connection to the NN.
> A job that performs many seeks will easily crash the NN due to fd exhaustion.



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