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From "Sumit Kumar (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-10634) Add recursive list apis to FileSystem to give implementations an opportunity for optimization
Date Wed, 28 May 2014 19:41:02 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-10634?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sumit Kumar updated HADOOP-10634:
---------------------------------

        Fix Version/s:     (was: 2.4.0)
    Affects Version/s: 2.4.0
               Status: Patch Available  (was: Open)

attached a patch that passes all the tests on top of hadoop 2.4.0 branch

> Add recursive list apis to FileSystem to give implementations an opportunity for optimization
> ---------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-10634
>                 URL: https://issues.apache.org/jira/browse/HADOOP-10634
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: fs/s3
>    Affects Versions: 2.4.0
>            Reporter: Sumit Kumar
>         Attachments: HADOOP-10634.patch
>
>
> Currently different code flows in hadoop use recursive listing to discover files/folders
in a given path. For example in FileInputFormat (both mapreduce and mapred implementations)
this is done while calculating splits. They however do this by doing listing level by level.
That means to discover files in /foo/bar means they do listing at /foo/bar first to get the
immediate children, then make the same call on all immediate children for /foo/bar to discover
their immediate children and so on. This doesn't scale well for fs implementations like s3
because every listStatus call ends up being a webservice call to s3. In cases where large
number of files are considered for input, this makes getSplits() call slow. 
> This patch adds a new set of recursive list apis that give opportunity to the s3 fs implementation
to optimize. The behavior remains the same for other implementations (that is a default implementation
is provided for other fs so they don't have to implement anything new). However for s3 it
provides a simple change (as shown in the patch) to improve listing performance.



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