Parallel Java UDF

Hi, I have a few questions regarding parallelisation in the Java UDF. Does the framework take care of the parallelisation or do I have to handle it inside my Java code ? If I have to program the parallelisation myself inside the Java code, are there examples available, showing how the process is done ? To put it more simply, is it possible to do a map/reduce-like parallelisation in Java UDF ? And how would I go about it ? Thank you.