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From "Brandon Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5171) NFS should create input stream for a file and try to share it with multiple read requests
Date Thu, 24 Oct 2013 19:02:03 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5171?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13804554#comment-13804554
] 

Brandon Li commented on HDFS-5171:
----------------------------------

Thank you, Haohui, for the patch.

It looks good. There is on possibility we need to handle: when a dfsclient is evicted, currently
we don't invalidate the input streams in the cache. Therefore, next time when one inputstream
is accessed, its associated dfsclient is not the original one. The read request would fail.


> NFS should create input stream for a file and try to share it with multiple read requests
> -----------------------------------------------------------------------------------------
>
>                 Key: HDFS-5171
>                 URL: https://issues.apache.org/jira/browse/HDFS-5171
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: nfs
>            Reporter: Brandon Li
>            Assignee: Haohui Mai
>         Attachments: HDFS-5171.000.patch, HDFS-5171.001.patch
>
>
> Currently, NFS creates an input steam for each read request and closes it after the request
is served. With lots of read request, the overhead is significant. 
> Like for write request, NFS should create input stream for a file and try to share it
with multiple read requests. The stream can be closed if there is no read request for a certain
amount of time (e.g., 10 sec).



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