[ https://issues.apache.org/jira/browse/MAPREDUCE-4893?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jason Lowe updated MAPREDUCE-4893: ---------------------------------- Fix Version/s: 0.23.7 Thanks, Bikas. I pulled this into branch-0.23 as well. > MR AppMaster can do sub-optimal assignment of containers to map tasks leading > to poor node locality > --------------------------------------------------------------------------------------------------- > > Key: MAPREDUCE-4893 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-4893 > Project: Hadoop Map/Reduce > Issue Type: Bug > Components: applicationmaster > Reporter: Bikas Saha > Assignee: Bikas Saha > Fix For: 2.0.3-alpha, 0.23.7 > > Attachments: MAPREDUCE-4893.1.patch, MAPREDUCE-4893.2.patch, > MAPREDUCE-4893.3.patch > > > Say the MR AppMaster asks the RM for 3 containers on nodes n1, n2 and n3. > There are 10 node n1-n10 in the same rack. The RM can give it allocated > containers in the list order n5, n2, n1. The way AM map->container assignment > happens, the AM will try to assign node local maps to n5, failing which it > will assign rack local maps to n5. These rack local maps could be node local > on n2 and n1 and would have been assigned to containers on n1 and n2 if the > AM had not made an early rack local match for them on n5. This can lead to > poor locality. -- 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