hadoop-mapreduce-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Sumit Kumar (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MAPREDUCE-5907) Improve getSplits() performance for fs implementations that can utilize performance gains from recursive listing
Date Thu, 29 May 2014 18:51:03 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-5907?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sumit Kumar updated MAPREDUCE-5907:
-----------------------------------

    Status: Open  (was: Patch Available)

Wasn't aware of Swift object store, thanks for pointing out.

Just for future reference, Swift object store implementation is HADOOP-8545 and i could find
code pieces in https://github.com/apache/hadoop-common/blob/trunk/hadoop-tools/hadoop-openstack

Will be posting test results for both s3 and swift object store performance along with merged
patch (changes for HADOOP-10634 included)

> 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
>         Attachments: 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
(v6.2#6252)

Mime
View raw message