Hadoop Map/Reduce
  1. Hadoop Map/Reduce
  2. MAPREDUCE-4228

mapreduce.job.reduce.slowstart.completedmaps is not working properly to delay the scheduling of the reduce tasks

    Details

      Description

      If no more map tasks need to be scheduled but not all have completed, the ApplicationMaster will start scheduling reducers even if the number of completed maps has not met the mapreduce.job.reduce.slowstart.completedmaps threshold. For example, if the property is set to 1.0 all maps should complete before any reducers are scheduled. However the reducers are scheduled as soon as the last map task is assigned to a container. For a job with very long-running maps, a cluster with enough capacity to launch all map tasks could cause reducers to launch prematurely and waste cluster resources.

      Thanks to Phil Su for discovering this issue.

      1. MAPREDUCE-4228.patch
        10 kB
        Jason Lowe
      2. MAPREDUCE-4228.patch
        10 kB
        Jason Lowe
      3. MAPREDUCE-4228.patch
        10 kB
        Jason Lowe

        Activity

        Arun C Murthy made changes -
        Status Resolved [ 5 ] Closed [ 6 ]
        Arun C Murthy made changes -
        Fix Version/s 2.0.2-alpha [ 12322471 ]
        Fix Version/s 3.0.0 [ 12320355 ]
        Fix Version/s 2.1.0-alpha [ 12321442 ]
        Robert Joseph Evans made changes -
        Status Patch Available [ 10002 ] Resolved [ 5 ]
        Fix Version/s 0.23.3 [ 12320060 ]
        Fix Version/s 2.0.1-alpha [ 12321442 ]
        Fix Version/s 3.0.0 [ 12320355 ]
        Resolution Fixed [ 1 ]
        Jason Lowe made changes -
        Attachment MAPREDUCE-4228.patch [ 12532955 ]
        Jason Lowe made changes -
        Status Open [ 1 ] Patch Available [ 10002 ]
        Jason Lowe made changes -
        Attachment MAPREDUCE-4228.patch [ 12525912 ]
        Jason Lowe made changes -
        Status Patch Available [ 10002 ] Open [ 1 ]
        Jason Lowe made changes -
        Status Open [ 1 ] Patch Available [ 10002 ]
        Target Version/s 0.23.3 [ 12320060 ]
        Jason Lowe made changes -
        Field Original Value New Value
        Attachment MAPREDUCE-4228.patch [ 12525892 ]
        Jason Lowe created issue -

          People

          • Assignee:
            Jason Lowe
            Reporter:
            Jason Lowe
          • Votes:
            2 Vote for this issue
            Watchers:
            11 Start watching this issue

            Dates

            • Created:
              Updated:
              Resolved:

              Development