[MAPREDUCE-1129] Assign multiple Map and Reduce tasks in Fairscheduler

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 0.20.1
• Component/s: contrib/fair-share
• Assignee: Unassigned
• Reporter: Scott Chen
• Created: 21/Oct/09 22:19
• Updated: 10/Nov/09 08:08
• Resolved: 10/Nov/09 07:29

Description

In Hadoop-0.20, the period of heartbeat becomes much longer.
Fairscheduler assigns at most one Map and one Reduce task per heartbeat.
This makes the cluster become very inefficient. Often time only half of the slots are used.

One idea is that we make Fairscheduler detect this situation (cluster under used) and scheduler more tasks in a heartbeat.
Thoughts?