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From "Runping Qi (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1965) Handle map output buffers better
Date Wed, 17 Oct 2007 12:12:51 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12535529
] 

Runping Qi commented on HADOOP-1965:
------------------------------------


It seems clear that threaded spill performed much better than sequence spill.

One thing surprising is that the spill times got worse as sort.io.mb increaseed.

This sounds counterintuitive. Any insights/explanations?


> Handle map output buffers better
> --------------------------------
>
>                 Key: HADOOP-1965
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1965
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: mapred
>            Reporter: Devaraj Das
>            Assignee: Amar Kamat
>         Attachments: 1965_single_proc_150mb_gziped.pdf
>
>
> Today, the map task stops calling the map method while sort/spill is using the (single
instance of) map output buffer. One improvement that can be done to improve performance of
the map task is to have another buffer for writing the map outputs to, while sort/spill is
using the first buffer.

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