JVM Reuse MapReduce 2.0 YARN
Yes. In yarn, the tasks run in a dedicated JVM. And unlike mapreduce 1, it doesn't support JVM reuse.
In mapreduce 1 however, the property for controlling task JVM reuse is mapred.job.reuse.jvm.num.tasks. Itspecifies the maximum number of tasks to run for a given job for each JVM launched and by default it is 1. This answer should give you a better idea about JVM reuse in 1.