[MAPREDUCE-1740] NPE in getMatchingLevelForNodes when node locations are variable depth

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.20.3
• Fix Version/s: 1.1.0, 2.0.0-alpha
• Component/s: jobtracker
• Target Version/s: 1.1.0
• Hadoop Flags: Reviewed
• Assignee: Ahmed Radwan
• Reporter: Todd Lipcon
• Created: 29/Apr/10 00:24
• Updated: 10/Mar/15 04:32
• Resolved: 20/Mar/12 18:37

Description

In getMatchingLevelForNodes, we assume that both nodes have the same "depth" (ie number of path components). If the user provides a topology script that assigns one node a path like /foo/bar/baz and another node a path like /foo/blah, this function will throw an NPE.

I'm not sure if there are other places where we assume that all node locations have a constant number of paths. If so we should check the output of the topology script aggressively to be sure this is the case. Otherwise I think we simply need to add && n2 != null to the while loop

Issue Links

• relates to: HADOOP-7103 When rack awareness script returns nothing, cluster stops working