Hadoop Map/Reduce
  1. Hadoop Map/Reduce
  2. MAPREDUCE-4733

Reducer can fail to make progress during shuffle if too many reducers complete consecutively

    Details

      Description

      TaskAttemptListenerImpl implements getMapCompletionEvents by calling Job.getTaskAttemptCompletionEvents with the same fromEvent and maxEvents passed in from the reducer and then filtering the result for just map events. We can't filter the task completion event list and expect the caller's "window" into the list to match up. As soon as a reducer event appears in the list it means we are redundantly sending map completion events that were already seen by the reducer.

      Worst case the reducer will hang if all of the events in the requested window are reducer events. In that case zero events will be reported back to the caller and it won't bump up fromEvent on the next call. Reducer then never sees the final map completion events needed to complete the shuffle. This could happen in a case where all maps complete, more than MAX_EVENTS reducers complete consecutively, but some straggling reducers get fetch failures and cause a map to be restarted.

      1. MAPREDUCE-4733.patch
        22 kB
        Jason Lowe
      2. MAPREDUCE-4733.patch
        21 kB
        Jason Lowe
      3. MAPREDUCE-4733.patch
        20 kB
        Jason Lowe

        Issue Links

          Activity

          Jason Lowe created issue -
          Jason Lowe made changes -
          Field Original Value New Value
          Assignee Jason Lowe [ jlowe ]
          Jason Lowe made changes -
          Attachment MAPREDUCE-4733.patch [ 12549801 ]
          Jason Lowe made changes -
          Status Open [ 1 ] Patch Available [ 10002 ]
          Target Version/s 2.0.3-alpha, 0.23.5 [ 12323275, 12323312 ]
          Jason Lowe made changes -
          Link This issue blocks MAPREDUCE-4730 [ MAPREDUCE-4730 ]
          Jason Lowe made changes -
          Attachment MAPREDUCE-4733.patch [ 12550001 ]
          Jason Lowe made changes -
          Attachment MAPREDUCE-4733.patch [ 12550053 ]
          Vinod Kumar Vavilapalli made changes -
          Status Patch Available [ 10002 ] Resolved [ 5 ]
          Hadoop Flags Reviewed [ 10343 ]
          Fix Version/s 2.0.3-alpha [ 12323275 ]
          Fix Version/s 0.23.5 [ 12323312 ]
          Resolution Fixed [ 1 ]
          Thomas Graves made changes -
          Status Resolved [ 5 ] Closed [ 6 ]
          Gavin made changes -
          Link This issue blocks MAPREDUCE-4730 [ MAPREDUCE-4730 ]
          Gavin made changes -
          Link This issue is depended upon by MAPREDUCE-4730 [ MAPREDUCE-4730 ]

            People

            • Assignee:
              Jason Lowe
              Reporter:
              Jason Lowe
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              Dates

              • Created:
                Updated:
                Resolved:

                Development