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Bikas Saha commented on TEZ-1248: --------------------------------- lgtm. seems like a simple code change whose side-effect produces the results for this jira :P > Reduce slow-start should special case 1 reducer runs > ---------------------------------------------------- > > Key: TEZ-1248 > URL: https://issues.apache.org/jira/browse/TEZ-1248 > Project: Apache Tez > Issue Type: Improvement > Affects Versions: 0.5.0 > Environment: 20 node cluster running tez > Reporter: Gopal V > Assignee: Zhiyuan Yang > Priority: Critical > Attachments: TEZ-1248.1.patch > > > Reducer slow-start has a performance problem for the small cases where there > is just 1 reducer for a case with a single wave. > Tez knows the split count and wave count, being able to determine if the > cluster has enough spare capacity to run the reducer earlier for lower > latency in a N-mapper -> 1 reducer case. -- This message was sent by Atlassian JIRA (v6.3.4#6332)