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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 Tue, 21 Aug 2012 07:27:38 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13438517#comment-13438517
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Ahmed Radwan commented on MAPREDUCE-4469:
-----------------------------------------

Thanks Tucu, It is not just streaming jobs. The approach in the previous patch only calculates
and updates resource counters every configurable number of skips (for example 10 skips instead
of doing such calculation with every update/hearbeat).
                
> 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
>            Assignee: Ahmed Radwan
>         Attachments: MAPREDUCE-4469.patch, MAPREDUCE-4469_rev2.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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