[YARN-4610] Reservations continue looking for one app causes other apps to starve

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 2.7.1
• Fix Version/s: 2.8.0, 2.7.3, 3.0.0-alpha1
• Component/s: capacityscheduler
• Target Version/s: 2.7.3
• Hadoop Flags: Reviewed
• Assignee: Jason Lowe
• Reporter: Jason Lowe
• Created: 19/Jan/16 21:50
• Updated: 05/Jan/17 22:50
• Resolved: 21/Jan/16 18:37

Description

CapacityScheduler's LeafQueue has "reservations continue looking" logic that allows an application to unreserve elsewhere to fulfil a container request on a node that has available space. However in 2.7 that logic seems to break allocations for subsequent apps in the queue. Once a user hits its user limit, subsequent apps in the queue for other users receive containers at a significantly reduced rate.

Issue Links

• is broken by: YARN-3434 Interaction between reservations and userlimit can result in significant ULF violation