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Hadoop >> mail # user >> heap size for the job tracker


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Mike S 2012-08-29, 02:10
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Re: heap size for the job tracker
Hi Mike,

On Wed, Aug 29, 2012 at 7:40 AM, Mike S <[EMAIL PROTECTED]> wrote:
> 1> Can I change the heap size for the job tracker only if I am using
> version 1.0.2?

Yes.

> 2>  If so, would you please say what exact line I should put in the
> hadoop-evv.sh and where ? Should I set the value with a number or use
> the Xmx notion?
>
> I mean which one is the correct way
>
> export HADOOP_HEAPSIZE=2000
>
> or
>
> export HADOOP_HEAPSIZE="-Xmx2000m"

The above (first one is right syntax) changes the heap across _all_
daemons, not just JT specifically. So you don't want to do that.

You may instead find and change the below line in hadoop-env.sh to the
following:

export HADOOP_JOBTRACKER_OPTS="$HADOOP_JOBTRACKER_OPTS -Xmx2g"

> 3> Do I need to restart the job tracker node or call start-mapred.sh
> to make the heap size change to take in effect? Is there anything else
> I need to do to make the change to be applied?

You will need to restart the JobTracker JVM for the new heap limit to
get used. You can run "hadoop-daemon.sh stop jobtracker" followed by
"hadoop-daemon.sh start jobtracker" to restart just the JobTracker
daemon (run the command on the JT node).

--
Harsh J