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From "Ahmed Radwan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4469) Resource calculation in child tasks is CPU-heavy
Date Mon, 06 Aug 2012 20:49:04 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13429412#comment-13429412
] 

Ahmed Radwan commented on MAPREDUCE-4469:
-----------------------------------------

Here is a patch that adds this option of disabling the use of  ResourceCalculatorPlugin in
the task. I have confirmed that this change doesn't affect TestTTResourceReporting.
                
> Resource calculation in child tasks is CPU-heavy
> ------------------------------------------------
>
>                 Key: MAPREDUCE-4469
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4469
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: performance, task
>    Affects Versions: 1.0.3
>            Reporter: Todd Lipcon
>         Attachments: MAPREDUCE-4469.patch
>
>
> In doing some benchmarking on a hadoop-1 derived codebase, I noticed that each of the
child tasks was doing a ton of syscalls. Upon stracing, I noticed that it's spending a lot
of time looping through all the files in /proc to calculate resource usage.
> As a test, I added a flag to disable use of the ResourceCalculatorPlugin within the tasks.
On a CPU-bound 500G-sort workload, this improved total job runtime by about 10% (map slot-seconds
by 14%, reduce slot seconds by 8%)

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