[MAPREDUCE-5748] Potential null pointer dereference in ShuffleHandler#Shuffle#messageReceived()

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Not A Problem
• Affects Version/s: 2.7.0
• Labels: BB2015-05-RFC
• Target Version/s: 2.8.0
• Assignee: Varun Saxena
• Reporter: Ted Yu
• Created: 08/Feb/14 16:20
• Updated: 01/Jul/15 09:48
• Resolved: 01/Jul/15 09:48

Description

Starting around line 510:

      ChannelFuture lastMap = null;
      for (String mapId : mapIds) {
...
      }
      lastMap.addListener(metrics);
      lastMap.addListener(ChannelFutureListener.CLOSE);

If mapIds is empty, lastMap would remain null, leading to NPE in addListener() call.