On Mon, May 18, 2009 at 11:44 AM, Steve Loughran <ste...@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). Tom
