[MAPREDUCE-5622] MRAppMaster doesn't assign all allocated NODE_LOCAL containers to node-local maps

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.2.0
• Component/s: applicationmaster
• Assignee: Unassigned
• Reporter: Devaraj Kavali
• Created: 13/Nov/13 06:23
• Updated: 13/Nov/13 15:40

Description

MRAppMaster will request containers for all the splits to launch map tasks, RM will give Node Local containers for all these if available. When the RM gives all containers as Node Local, MR AM may assign these NODE-LOCAL containers to non-local maps.

node1	split1	split2		split4
node2		split2	split3
node3	split1	split2	split3	split4
node4	split1		split3	split4

Consider this instance, assume RM has given one NODE LOCAL container on each node to process all the splits as local maps. While assigning, if the AM gives node1-container for split1, node2-container for split3, node3-container for split3 and node4-container can be given to only split2 which is not local.

Issue Links

• relates to: MAPREDUCE-4893 MR AppMaster can do sub-optimal assignment of containers to map tasks leading to poor node locality