[YARN-4617] LeafQueue#pendingOrderingPolicy should always use fixed ordering policy instead of using same as active applications ordering policy

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.8.0
• Fix Version/s: 2.8.0, 3.0.0-alpha1
• Component/s: capacity scheduler
• Target Version/s: 2.8.0
• Hadoop Flags: Reviewed
• Assignee: Rohith Sharma K S
• Reporter: Rohith Sharma K S
• Created: 21/Jan/16 04:04
• Updated: 30/Aug/16 01:06
• Resolved: 29/Jan/16 20:23

Description

In discussion with leftnoteasy in the JIRA comment pointed out that LeafQueue#pendingOrderingPolicy should NOT be assumed to be same as active applications ordering policy. It causes an issue when using fair ordering policy.
Expectations of this JIRA should include

1. Create FifoOrderingPolicyForPendingApps which extends FifoOrderingPolicy.
2. Comparator of new ordering policy should use RecoveryComparator,PriorityComparator and Fifocomparator in order respectively.
3. Clean up LeafQueue#pendingOPForRecoveredApps which is no more required once new fixed ordering policy is created pending applications.