Storage of large amount of global variables in MapReduce in java -

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if need use more 1 reducer reduce job our global variables stored considering 1 reducer cannot have memory global data of job.

are stored in hdfs , accessed each reducer?

or

we need explicitly.

no. not stored in hdfs. need not explicitly.

each of reducer run in separate jvm , reducer instance have it's own variables maintained in jvm heap memory area. each of reducer have own instance of global or local variables. object creation , storage same normal java program. there nothing special happen mapper or reducer objects.


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