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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1719) Improve the utilization of shuffle copier threads
Date Sat, 18 Aug 2007 16:16:30 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1719?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12520862
] 

Hadoop QA commented on HADOOP-1719:
-----------------------------------

-1, new javadoc warnings

The javadoc tool appears to have generated warning messages when testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12364036/1719.1.patch against trunk revision
r566886.

Test results:   http://lucene.zones.apache.org:8080/hudson/job/Hadoop-Patch/566/testReport/
Console output: http://lucene.zones.apache.org:8080/hudson/job/Hadoop-Patch/566/console

Please note that this message is automatically generated and may represent a problem with
the automation system and not the patch.

> Improve the utilization of shuffle copier threads
> -------------------------------------------------
>
>                 Key: HADOOP-1719
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1719
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: mapred
>            Reporter: Devaraj Das
>            Assignee: Devaraj Das
>             Fix For: 0.15.0
>
>         Attachments: 1719.1.patch, 1719.patch
>
>
> In the current design, the scheduling of copies is done and the scheduler (the main loop
in fetchOutputs) won't schedule anything until it hears back from at least one of the copier
threads. Due to this, the main loop won't query the TaskTracker asking for new map locations
and may not be using all the copiers effectively. This may not be an issue for small-sized
map outputs, where at steady state, the frequency of such notifications is frequent.
> Ideally, we should schedule all what we can, and, depending on how busy we currently
are, query the tasktracker for more map locations.

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