Is it possible to run several map task in one JVM?

Question

I want to share large in memory static data(RAM lucene index) for my map tasks in Hadoop? Is there way for several map/reduce tasks to share same JVM?

Answer 1

Shameless plug

I go over using static objects with JVM reuse to accomplish what you describe here: http://chasebradford.wordpress.com/2011/02/05/distributed-cache-static-objects-and-fast-setup/

Another option, although more complicated, is to use distributed cache with a read-only memory mapped file. That way you can share the resource across the JVM processes as well.