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https://issues.apache.org/jira/browse/HDFS-7224?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14291862#comment-14291862
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Kihwal Lee commented on HDFS-7224:
----------------------------------
I've committed this to branch-2 and trunk. Thanks for working on this, Eric,
and for the review, Daryn.
> Allow reuse of NN connections via webhdfs
> -----------------------------------------
>
> Key: HDFS-7224
> URL: https://issues.apache.org/jira/browse/HDFS-7224
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: webhdfs
> Affects Versions: 2.5.0
> Reporter: Eric Payne
> Assignee: Eric Payne
> Fix For: 2.7.0
>
> Attachments: HDFS-7224.v1.201410301923.txt,
> HDFS-7224.v2.201410312033.txt, HDFS-7224.v3.txt, HDFS-7224.v4.txt
>
>
> In very large clusters, the webhdfs client could get bind exceptions because
> it runs out of ephemeral
> ports. This could happen when using webhdfs to talk to the NN in order to do
> list globbing of a
> huge amount of files.
> WebHdfsFileSystem#jsonParse gets the input/error stream from the connection,
> but never closes the stream. Since it's not closed, the JVM thinks the stream
> may still
> be transferring data, so the next time through this code, it has to get a new
> connection
> rather than reusing an existing one.
> The lack of connection reuse has poor latency and adds too much overhead to
> the NN.
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