Yep. I have tried the option apred.job.reuse.jvm.num.tasks with -1. There is no big difference. Furthermore, even using this option with -1, there are still several task jvms besides the tasktracker jvm.
On Mon, May 18, 2009 at 9:34 PM, Steve Loughran <ste...@apache.org> wrote: > Tom White wrote: > >> 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 >> > > Tom, > that's why you are writing a book on Hadoop and I'm not ...you know the > answers and I have some vague misunderstandings, > > -steve > (returning to the svn book) >
