Vasco created MAPREDUCE-4613:
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Summary: Scheduling of reduce tasks results in starvation
Key: MAPREDUCE-4613
URL: https://issues.apache.org/jira/browse/MAPREDUCE-4613
Project: Hadoop Map/Reduce
Issue Type: Bug
Components: scheduler
Affects Versions: 0.23.1
Environment: 16 machine cluster
Reporter: Vasco
If a job has more reduce tasks than there are containers available, then the
reduce tasks can occupy all containers causing starvation.
I understand that the correct behaviour when all containers are taken by
reducers while mappers are still pending, is for the running reducers to be
"pre-empted". However, pre-emption does not occur.
A work-around is to set the number of reducers < available containers.
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