[YARN-1128] FifoPolicy.computeShares throws NPE on empty list of Schedulables

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.1.0-beta
• Fix Version/s: 2.2.0
• Component/s: scheduler
• Hadoop Flags: Reviewed
• Assignee: Karthik Kambatla
• Reporter: Sandy Ryza
• Created: 30/Aug/13 19:31
• Updated: 30/Jun/15 07:20
• Resolved: 25/Sep/13 02:30

Description

FifoPolicy gives all of a queue's share to the earliest-scheduled application.

    Schedulable earliest = null;
    for (Schedulable schedulable : schedulables) {
      if (earliest == null ||
          schedulable.getStartTime() < earliest.getStartTime()) {
        earliest = schedulable;
      }
    }
    earliest.setFairShare(Resources.clone(totalResources));

If the queue has no schedulables in it, earliest will be left null, leading to an NPE on the last line.