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From Tom White <...@cloudera.com>
Subject Re: Is there any performance issue with Jrockit JVM for Hadoop
Date Mon, 18 May 2009 13:09:25 GMT
On Mon, May 18, 2009 at 11:44 AM, Steve Loughran <stevel@apache.org> wrote:
> Grace wrote:
>> To follow up this question, I have also asked help on Jrockit forum. They
>> kindly offered some useful and detailed suggestions according to the JRA
>> results. After updating the option list, the performance did become better
>> to some extend. But it is still not comparable with the Sun JVM. Maybe, it
>> is due to the use case with short duration and different implementation in
>> JVM layer between Sun and Jrockit. I would like to be back to use Sun JVM
>> currently. Thanks all for your time and help.
> what about flipping the switch that says "run tasks in the TT's own JVM?".
> That should handle startup costs, and reduce the memory footprint

The property mapred.job.reuse.jvm.num.tasks allows you to set how many
tasks the JVM may be reused for (within a job), but it always runs in
a separate JVM to the tasktracker. (BTW
https://issues.apache.org/jira/browse/HADOOP-3675has some discussion
about running tasks in the tasktracker's JVM).


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