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Posted to common-user@hadoop.apache.org by Saptarshi Guha <sa...@gmail.com> on 2010/03/16 22:41:33 UTC

Number of combiner threads in a JVM

Hello,
If a combiner is set, the combiner might run in parallel with the map
or the reducer.
I say might because it is not guaranteed that the combiner will run.

Q: How many combiner threads in a JVM are run in parallel? One? So,
for example, suppose
a map is processing its tasks will there be a single combiner thread
(if at all) running in parallel?


Thank you
Sapsi