[MAPREDUCE-962] NPE in ProcfsBasedProcessTree.destroy()

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.21.0
• Fix Version/s: 0.21.0
• Component/s: tasktracker
• Hadoop Flags: Reviewed
• Release Note: Fixes an issue of NPE in ProcfsBasedProcessTree in a corner case.
• Assignee: Ravi Gummadi
• Reporter: Vinod Kumar Vavilapalli
• Created: 02/Sep/09 11:22
• Updated: 24/Aug/10 21:17
• Resolved: 05/Nov/09 06:14

Description

This causes the following exception in TaskMemoryManagerThread. I observed this while running TestTaskTrackerMemoryManager.

2009-09-02 12:08:25,835 WARN  mapred.TaskMemoryManagerThread (TaskMemoryManagerThread.java:run(239)) - \
            Uncaught exception in TaskMemoryManager while managing memory of attempt_20090902120812252_0001_m_000003_0 : \
java.lang.NullPointerException
        at org.apache.hadoop.util.ProcfsBasedProcessTree.assertPidPgrpidForMatch(ProcfsBasedProcessTree.java:234)
        at org.apache.hadoop.util.ProcfsBasedProcessTree.assertAndDestroyProcessGroup(ProcfsBasedProcessTree.java:257)
        at org.apache.hadoop.util.ProcfsBasedProcessTree.destroy(ProcfsBasedProcessTree.java:286)
        at org.apache.hadoop.mapred.TaskMemoryManagerThread.run(TaskMemoryManagerThread.java:229)