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https://issues.apache.org/jira/browse/MAPREDUCE-4907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13549222#comment-13549222
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Hadoop QA commented on MAPREDUCE-4907:
--------------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest 
attachment 
  
http://issues.apache.org/jira/secure/attachment/12564059/MAPREDUCE-4907-trunk-1.patch
  against trunk revision .

    {color:green}+1 @author{color}.  The patch does not contain any @author 
tags.

    {color:green}+1 tests included{color}.  The patch appears to include 1 new 
or modified test files.

    {color:green}+1 javac{color}.  The applied patch does not increase the 
total number of javac compiler warnings.

    {color:green}+1 javadoc{color}.  The javadoc tool did not generate any 
warning messages.

    {color:green}+1 eclipse:eclipse{color}.  The patch built with 
eclipse:eclipse.

    {color:green}+1 findbugs{color}.  The patch does not introduce any new 
Findbugs (version 1.3.9) warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase 
the total number of release audit warnings.

    {color:red}-1 core tests{color}.  The patch failed these unit tests in 
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core:

                  
org.apache.hadoop.mapreduce.filecache.TestClientDistributedCacheManager

    {color:green}+1 contrib tests{color}.  The patch passed contrib unit tests.

Test results: 
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/3224//testReport/
Console output: 
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/3224//console

This message is automatically generated.
                
> 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
>         Attachments: MAPREDUCE-4907.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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