[jira] Created: (MAPREDUCE-1308) reduce tasks stall and are eventually killed

["Brian Karlak (JIRA)" <ji...@apache.org>]

reduce tasks stall and are eventually killed
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                 Key: MAPREDUCE-1308
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1308
             Project: Hadoop Map/Reduce
          Issue Type: Bug
          Components: tasktracker
         Environment: 20-node cluster, 8 cores per machine, 32GB memory, Fedora Linux
            Reporter: Brian Karlak


We recently migrated our 0.19.2 cluster from Gentoo Linux to Fedora Linux.  Everything was running smoothly before, but now about 5%-10% of our jobs have at least one reduce task that stalls out and is eventually killed with the message:

      Task attempt_200912102211_1648_r_000009_0 failed to report status for 6003 seconds. Killing!

The task is then re-launched and completes successfully, usually in a couple of minutes.

This is problematic because our scheduled Hadoop jobs now take an extra hour-and-a-half to run (6000 seconds).

There are no indications in the logs that anything is amiss.  The task starts, a small amount of the copy/shuffle runs, and then nothing is else is heard from the task until it is killed.  I will attach the relevant parts of the TaskTracker logs in the comments.


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