[
https://issues.apache.org/jira/browse/MAPREDUCE-5907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15967303#comment-15967303
]
Steve Loughran commented on MAPREDUCE-5907:
-------------------------------------------
seems good. don't feel bad about pinging me every week or so for a review: I
know how frustrating it is for things to be left, and this patch is an example
of how neglecting patch review is bad: the patch ages and the effort to pull it
in increases.
Alongside this work, a test for S3A can go in: created HADOOP-14302. It's a
separate JIRA so this patch doesn't depend on it.
[~blue_impala_48d6] might have some insights here, being as he'd benefit from
this.
> Improve getSplits() performance for fs implementations that can utilize
> performance gains from recursive listing
> ----------------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-5907
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5907
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: client
> Affects Versions: 2.4.0
> Reporter: Sumit Kumar
> Assignee: Sumit Kumar
> Labels: BB2015-05-TBR
> Attachments: MAPREDUCE-5907-2.patch, MAPREDUCE-5907-3.patch,
> MAPREDUCE-5907.patch
>
>
> FileInputFormat (both mapreduce and mapred implementations) use recursive
> listing 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 object store based fs implementations like s3
> and swift because every listStatus call ends up being a webservice call to
> backend. 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 gives opportunity to
> the fs implementations 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 objectstore based fs
> implementations it provides a simple change to include recursive flag as true
> (as shown in the patch) to improve listing performance.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
