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Date: Mon, 4 Dec 2017 13:03:00 +0000 (UTC)
From: "ASF GitHub Bot (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (MAPREDUCE-7017) Too many times of meaningless
 invocation in TaskAttemptImpl#resolveHosts
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archived-at: Mon, 04 Dec 2017 13:03:05 -0000


    [ https://issues.apache.org/jira/browse/MAPREDUCE-7017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16276739#comment-16276739 ] 

ASF GitHub Bot commented on MAPREDUCE-7017:
-------------------------------------------

GitHub user jiayuhan-it opened a pull request:

    https://github.com/apache/hadoop/pull/309

    MAPREDUCE-7017:Too many times of meaningless invocation in TaskAttemptImpl#resolveHosts

    MRAppMaster uses TaskAttemptImpl::resolveHosts to determine the dataLocalHosts for each task when the location of data split is IP, which will call a lot of times ( taskNum * dfsReplication) of function InetAddress::getByName and most of the funcition calls are redundant. When the job has a great number of tasks and the speed of DNS resolution is not fast enough, it will take a lot of time at this stage before the job running.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/jiayuhan-it/hadoop trunk

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/hadoop/pull/309.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #309
    
----
commit fd42cd960bcfc40fd479d9af0109b15f21a11811
Author: jiayuhan <jiayuhan-it@360.cn>
Date:   2017-12-04T10:46:42Z

    Too many times of meaningless invocation in TaskAttemptImpl#resolveHosts

----


> Too many times of meaningless invocation in TaskAttemptImpl#resolveHosts
> ------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-7017
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-7017
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: mr-am
>    Affects Versions: 3.0.0-alpha4
>            Reporter: jiayuhan-it
>         Attachments: MAPREDUCE-7017.001.patch
>
>
>   MRAppMaster uses {{TaskAttemptImpl::resolveHosts}} to determine the dataLocalHosts for each task when the location of data split is IP, which will call a lot of times ( taskNum * dfsReplication) of function {{InetAddress::getByName}} and most of the funcition calls are redundant.  When the job has a great number of tasks and the speed of DNS resolution is not fast enough, it will take a lot of time at this stage before the job running.


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