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From Serge Blazhiyevskyy <Serge.Blazhiyevs...@nice.com>
Subject Re: mapred.tasktracker.map.tasks.maximum
Date Tue, 13 Nov 2012 15:23:10 GMT
Look on the job tracker web UI is parameter has taken effect (port 50030)

It might be in the wrong config file or something


From: Mark Kerzner <mark.kerzner@shmsoft.com<mailto:mark.kerzner@shmsoft.com>>
Reply-To: "user@hadoop.apache.org<mailto:user@hadoop.apache.org>" <user@hadoop.apache.org<mailto:user@hadoop.apache.org>>
Date: Tuesday, November 13, 2012 5:19 PM
To: "user@hadoop.apache.org<mailto:user@hadoop.apache.org>" <user@hadoop.apache.org<mailto:user@hadoop.apache.org>>
Subject: Re: mapred.tasktracker.map.tasks.maximum


On Tue, Nov 13, 2012 at 10:18 AM, Serge Blazhiyevskyy <Serge.Blazhiyevskyy@nice.com<mailto:Serge.Blazhiyevskyy@nice.com>>
What hadoop version are we talking about?

From: Mark Kerzner <mark.kerzner@shmsoft.com<mailto:mark.kerzner@shmsoft.com><mailto:mark.kerzner@shmsoft.com<mailto:mark.kerzner@shmsoft.com>>>
Reply-To: "user@hadoop.apache.org<mailto:user@hadoop.apache.org><mailto:user@hadoop.apache.org<mailto:user@hadoop.apache.org>>"
Date: Tuesday, November 13, 2012 5:16 PM
To: Hadoop User <user@hadoop.apache.org<mailto:user@hadoop.apache.org><mailto:user@hadoop.apache.org<mailto:user@hadoop.apache.org>>>
Subject: mapred.tasktracker.map.tasks.maximum


I have a cluster with 4 nodes and 32 many cores on each. My default value for the maximum
number of mappers per slot is 1:

    <!-- see other kb entry about this one. -->
(which I think is wrong).

Howeve, when sizable jobs run, I see 65 mappers working, so it seems that it does create more
than 1 mapper per node.

Questions: what maximum number of mappers would be appropriate in this situation? Is that
the right way to set them?

Thank you. Sincerely,

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