[YARN-6210] FS: Node reservations can interfere with preemption

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.9.0
• Fix Version/s: 2.9.0, 3.0.0-alpha4
• Component/s: fairscheduler
• Target Version/s: 2.9.0
• Hadoop Flags: Reviewed
• Assignee: Karthik Kambatla
• Reporter: Karthik Kambatla
• Created: 21/Feb/17 02:18
• Updated: 23/Feb/17 22:31
• Resolved: 22/Feb/17 23:53

Description

Today, on a saturated cluster, apps with pending demand reserve nodes. A new app might not be able to preempt resources because these nodes are already reserved. This can be reproduced by the example in YARN-6151.

Since node reservations are to prevent starvation of apps requesting large containers, triggering these reservations only on starved applications would avoid this situation.

Issue Links

• is duplicated by: YARN-6176 Test whether FS preemption consider child queues over fair share if the parent is under fair share
• relates to: YARN-6215 FairScheduler preemption and update should not run concurrently