In a mapreduce job, a given map JVM will run N map tasks. Are the
configure and close methods executed for every one of these N tasks?
Or is configure executed once when the JVM starts and the close method
executed once when all N have been completed?
I have the same question for the reduce task. Will it be run before
for every reduce task? And close is run when all the values for a
given key have been processed?
We can assume there isn't a combiner.