[MAPREDUCE-5583] Ability to limit running map and reduce tasks

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.23.9, 2.1.1-beta
• Fix Version/s: 2.7.0
• Component/s: mr-am, mrv2
• Hadoop Flags: Reviewed

Release Note

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This introduces two new MR2 job configs, mentioned below, which allow users to control the maximum simultaneously-running tasks of the submitted job, across the cluster:

* mapreduce.job.running.map.limit (default: 0, for no limit)
* mapreduce.job.running.reduce.limit (default: 0, for no limit)

This is controllable at a per-job level.

• Assignee: Jason Darrell Lowe
• Reporter: Jason Darrell Lowe
• Created: 14/Oct/13 21:16
• Updated: 15/Apr/20 16:00
• Resolved: 03/Mar/15 10:16

Description

It would be nice if users could specify a limit to the number of map or reduce tasks that are running simultaneously. Occasionally users are performing operations in tasks that can lead to DDoS scenarios if too many tasks run simultaneously (e.g.: accessing a database, web service, etc.). Having the ability to throttle the number of tasks simultaneously running would provide users a way to mitigate issues with too many tasks on a large cluster attempting to access a serivce at any one time.

This is similar to the functionality requested by MAPREDUCE-224 and implemented by HADOOP-3412 but was dropped in mrv2.

Issue Links

• is duplicated by: MAPREDUCE-6176 To limit the map task number or reduce task number of an application
• is related to: YARN-3274 FIFOScheduler should assign the same container number up to ResourceRequest ask for ANY
• is related to: MAPREDUCE-6697 Concurrent task limits should only be applied when necessary
• is related to: MAPREDUCE-7274 Enable to limit running map and reduce tasks when job is running
• relates to: MAPREDUCE-224 limit running tasks per job
• relates to: HADOOP-5170 Set max map/reduce tasks on a per-job basis, either per-node or cluster-wide