hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Arun C Murthy (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5160) Hadoop reduce scheduler sometimes leaves machines idle
Date Fri, 06 Feb 2009 21:44:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12671343#action_12671343
] 

Arun C Murthy commented on HADOOP-5160:
---------------------------------------

Were other jobs 'alive' in the system when this happened or was this the only other job in
the queue?

> Hadoop reduce scheduler sometimes leaves machines idle
> ------------------------------------------------------
>
>                 Key: HADOOP-5160
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5160
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>            Reporter: Nathan Marz
>
> I have a MapReduce application with number of reducers equal to the number of machines
in the cluster (and with speculative execution turned off). However, Hadoop schedules multiple
reduces to run on single machines and leaves other machines idle. This causes contention and
seriously slows down the job. Hadoop should employ the simple heuristic of utilizing as many
machines as possible when scheduling reduces.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message