Damien Hardy created MAPREDUCE-5019: ---------------------------------------
Summary: Fair scheduler should allow peremption on reducer only Key: MAPREDUCE-5019 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5019 Project: Hadoop Map/Reduce Issue Type: Improvement Components: mrv1, scheduler Affects Versions: 2.0.2-alpha Environment: CDH4.1.2 Reporter: Damien Hardy Priority: Minor Fair scheduler is very good. But having a big MR job running lots of mapper and reducer( 10M + 10R ) Then a small MR on the same pool (1M + 1R) having slots for 10 mapper and 10 reducer - The big job take all the map slots - The small job wait for a map slot - 1rst big job map task finish - the small job take the map slot it needs - meanwhile all the reducer of the big job take all the reducer slot to copy and sort - the small job end is map and wait for the all maps to end and for 1 reducer to end before accessing for a reducer slot. - all the reducer stalled after sorting waiting for the mapper to end one by one... If I have a big job and a lot of small, I don't want new small arriving and killing running map tasks of big job to get a slot. I think it could be useful that the small job can kill a reducer tasks (and only reducer) to end before the big job finish all its map tasks and a reducer. rules can be : a job having all its map finished and waiting for reducer slot can kill reducer tasks from a job that still have map slot running (assuming they are just waiting for copy and sort) -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira