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Hi I have a Map Reduce task say AverageScoreCalculator which has mapper and reducer.
the question is i static initialitze few fields in AverageScoreCalculator will that be avialable to both mapper and reducer ?
By default, each map and reduce task runs in a different JVM and there can be multiple JVMs running at any particular instance on a node.
Set the following properties
and there will be only a single mapper/reducer running on a given node with JVM reuse and the reducers won’t start until all the mappers have completed processing.
Couple of things to note
The above approach works with MapReduce 1x release and is not an efficient approach.
JVM reuse is not supported in MapReduce 2x release.