[MAPREDUCE-6697] Concurrent task limits should only be applied when necessary

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.7.0
• Fix Version/s: 2.9.0, 2.7.4, 3.0.0-alpha4, 2.8.2
• Component/s: mrv2
• Target Version/s: 2.7.4
• Hadoop Flags: Reviewed
• Assignee: Nathan Roberts
• Reporter: Jason Darrell Lowe
• Created: 16/May/16 22:52
• Updated: 14/Jul/17 00:40
• Resolved: 14/Jul/17 00:40

Description

The concurrent task limit feature should only adjust the ANY portion of the AM heartbeat ask when a limit is truly necessary, otherwise extraneous containers could be allocated by the RM to the AM adding some overhead to both. Specifying a concurrent task limit that is beyond the total number of tasks in the job should be the same as asking for no limit.

Issue Links

• relates to: MAPREDUCE-5583 Ability to limit running map and reduce tasks