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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-2036) Mappers are not running locally
Date Fri, 03 Jan 2014 05:46:53 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-2036?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13861243#comment-13861243
] 

Josh Elser commented on ACCUMULO-2036:
--------------------------------------

Verified no (or, at least, very little) data locality before the fix, and nearly 100% data
locality after the fix.

> Mappers are not running locally
> -------------------------------
>
>                 Key: ACCUMULO-2036
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2036
>             Project: Accumulo
>          Issue Type: Bug
>            Reporter: Keith Turner
>            Assignee: Josh Elser
>              Labels: 16_qa_bug
>             Fix For: 1.6.0
>
>
> I ran listscans in the Accumulo shell while running continuous verify on small cluster
and almost not map task were running locally.
> I think ACCUMULO-1585 has broken mapper locality in 1.6.0-SNAPSHOT.  Before that change
Accumulo would always store IP addrs.  Code like the following in o.a.a.c.client.mapreduce.AbstractInputFormat.getSplits()
would translate IPs to hostnames.  
> {code:java}
>        if (location == null) {
>           InetAddress inetAddress = InetAddress.getByName(ip);
>           location = inetAddress.getHostName();
>           hostNameCache.put(ip, location);
>         }
> {code}
> In my case I configured Accumulo to use hostnames, but not fully qualified ones.  So
I think the above code was just passing the non-quallified hostname through.   I suspected
hadoop wanted FQDN and changed the code to the following and mappers ran locally.  I need
to confirm what hadoop is expecting.  I think the above code will result in a FQDN if given
an IP,  so this is not an issue for 1.4 or 1.5.
> {code:java}
>        if (location == null) {
>           InetAddress inetAddress = InetAddress.getByName(ip);
>           location = inetAddress.getCanonicalHostName();
>           hostNameCache.put(ip, location);
>         }
> {code}



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