On Wed, Jun 3, 2009 at 10:59 AM, Tarandeep Singh <tarand...@gmail.com>wrote:
> I want to share a object (Lucene Index Writer Instance) between mappers > running on same node of 1 job (not across multiple jobs). Please correct me > if I am wrong - > > If I set the -1 for the property: mapred.job.reuse.jvm.num.tasks then all > mappers of one job will be executed in the same jvm and in that case if I > create a static Lucene Index Writer instance in my mapper class, all > mappers > running on the same node will be able to use it. > Not quite. The JVM reuse controls whether the JVM will be terminated after a single mapper run and a new one created for the next. It doesn't influence how many JVMs are created -- you will still get one jvm per mapper or reducer. I think there is, or was, or maybe a patch enables, what you are asking for, IIRC.
