Allow mapred.fairscheduler.assignmultple to be set per job
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Key: MAPREDUCE-2905
URL: https://issues.apache.org/jira/browse/MAPREDUCE-2905
Project: Hadoop Map/Reduce
Issue Type: Improvement
Components: contrib/fair-share
Reporter: Jeff Bean
We encountered a situation where in the same cluster, large jobs benefit from
mapred.fairscheduler.assignmultiple, but small jobs with small numbers of
mappers do not: the mappers all clump to fully occupy just a few nodes, which
causes those nodes to saturate and bottleneck. The desired behavior is to
round-robin spread the job across more nodes.
It'd be nice developers can set a param similar to
mapred.fairscheduler.assignmultiple on a per-job basis to better control the
task allocation of a particular job.
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