Post by Admin on Mar 14, 2014 6:59:00 GMT
Ans: Task instances are the actual MapReduce jobs which run on each slave node. The TaskTracker starts a separate JVM processes to do the actual work
(called as Task Instance) this is to ensure that process failure does not take down he entire task tracker.Each Task Instance runs on its own JVM process. There
can be multiple processes of task instance running on a slave node. This is based on the number of slots configured on task tracker. By default a new task
instance JVM process is spawned for a task.