[YARN-5350] Distributed Scheduling: Ensure sort order of allocatable nodes returned by the RM is not lost

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.9.0, 3.0.0-alpha1
• Assignee: Arun Suresh
• Reporter: Arun Suresh
• Created: 11/Jul/16 00:38
• Updated: 13/Nov/17 22:49
• Resolved: 20/Jul/16 06:27

Description

The LocalScheduler receives an ordered list of nodes from the RM with each allocate call. This list, which is used by the LocalScheduler to allocate OPPORTUNISTIC containers, is sorted on the Nodes free capacity (queue length / wait time).

Unfortunately, the LocalScheduler stores this list in a HashMap thereby losing the sort order.

The trivial fix would be to replace the HashMap with a LinkedHashMap which retains the insertion order.