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Date: Tue, 1 Jul 2008 07:00:45 -0700 (PDT)
From: "Runping Qi (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Commented: (HADOOP-3651) When assigning tasks to trackers,
 the job tracker should try to balance the number of tasks among the
 available trackers
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    [ https://issues.apache.org/jira/browse/HADOOP-3651?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12609598#action_12609598 ] 

Runping Qi commented on HADOOP-3651:
------------------------------------

Not sure how the original cases were produced.
I'll get more details if I encounter the same problem in the future.


> When assigning tasks to trackers, the job tracker should try to balance the number of tasks among the available trackers
> ------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-3651
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3651
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: mapred
>    Affects Versions: 0.17.0
>            Reporter: Runping Qi
>
> I encounter a number of situations like this:
> A job tracker has 200 task trackers, each with 2 mapper slots and reducer slots.
> When a job with 200 or fewer reducers was submitted to the job tracker,
> one normally each task tracker will run one reducer.
> Unfortunately, it seems that only  about 1/3 of trackers have one reducer, and 1/3 trackers don't have reducer, and 1/3 have 2 reducers!

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