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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-3612) Resource calculation in child tasks is CPU-heavy
Date Tue, 07 Jul 2015 20:56:06 GMT

    [ https://issues.apache.org/jira/browse/YARN-3612?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14617391#comment-14617391

Chris Douglas commented on YARN-3612:

bq. Moreover, I have not added the config as I do not see anyone disabling it. Thoughts ?

The config change could be useful for MR jobs that want to avoid the CPU overhead. Suggest
changing calls to {{nanoTime}} from {{currentTimeMillis}} since it's measuring durations.

+1 overall, even without the change to {{Task}}.

> Resource calculation in child tasks is CPU-heavy
> ------------------------------------------------
>                 Key: YARN-3612
>                 URL: https://issues.apache.org/jira/browse/YARN-3612
>             Project: Hadoop YARN
>          Issue Type: Bug
>    Affects Versions: 2.7.0
>            Reporter: Todd Lipcon
>              Labels: BB2015-05-RFC, performance
>         Attachments: MAPREDUCE-4469.patch, MAPREDUCE-4469_rev2.patch, MAPREDUCE-4469_rev3.patch,
MAPREDUCE-4469_rev4.patch, MAPREDUCE-4469_rev5.patch, YARN-3612.01.patch, YARN-3612.02.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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