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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4907) TrackerDistributedCacheManager issues too many getFileStatus calls
Date Fri, 11 Jan 2013 10:48:16 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13551038#comment-13551038

Hudson commented on MAPREDUCE-4907:

Integrated in Hadoop-Yarn-trunk #93 (See [https://builds.apache.org/job/Hadoop-Yarn-trunk/93/])
    MAPREDUCE-4907. Ammendment, forgot to svn add testcase in original commit (Revision 1431510)

     Result = SUCCESS
tucu : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1431510
Files : 
* /hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/filecache
* /hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/filecache/TestClientDistributedCacheManager.java

> TrackerDistributedCacheManager issues too many getFileStatus calls
> ------------------------------------------------------------------
>                 Key: MAPREDUCE-4907
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4907
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: mrv1, tasktracker
>    Affects Versions: 1.1.1
>            Reporter: Sandy Ryza
>            Assignee: Sandy Ryza
>             Fix For: 1.2.0, 2.0.3-alpha
>         Attachments: MAPREDUCE-4907.patch, MAPREDUCE-4907-trunk-1.patch, MAPREDUCE-4907-trunk-1.patch,
MAPREDUCE-4907-trunk-1.patch, MAPREDUCE-4907-trunk.patch
> TrackerDistributedCacheManager issues a number of redundant getFileStatus calls when
determining the timestamps and visibilities of files in the distributed cache.  300 distributed
cache files deep in the directory structure can hammer HDFS with a couple thousand requests.
> A couple optimizations can reduce this load:
> 1. determineTimestamps and determineCacheVisibilities both call getFileStatus on every
file.  We could cache the results of the former and use them for the latter.
> 2. determineCacheVisibilities needs to check that all ancestor directories of each file
have execute permissions for everyone.  This currently entails a getFileStatus on each ancestor
directory for each file.  The results of these getFileStatus calls could be cached as well.

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