[YARN-6681] Eliminate double-copy of child queues in canAssignToThisQueue

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.8.0
• Fix Version/s: 2.9.0, 3.0.0-beta1, 2.8.2
• Component/s: resourcemanager
• Target Version/s: 2.8.2
• Hadoop Flags: Reviewed
• Assignee: Daryn Sharp
• Reporter: Daryn Sharp
• Created: 01/Jun/17 16:56
• Updated: 01/Jul/17 10:52
• Resolved: 01/Jul/17 07:31

Description

20% of the time in AbstractCSQueue#canAssignToThisQueue is spent performing two duplications a treemap of child queues into a list - once to test for null, second to see if it's empty. Eliminating the dups reduces the overhead to 2%.