Hadoop Map/Reduce
  1. Hadoop Map/Reduce
  2. MAPREDUCE-2905

CapBasedLoadManager incorrectly allows assignment when assignMultiple is true (was: assignmultiple per job)

    Details

    • Type: Bug Bug
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: 0.20.2
    • Fix Version/s: 1.1.0
    • Component/s: contrib/fair-share
    • Labels:
      None
    • Target Version/s:
    • Hadoop Flags:
      Reviewed

      Description

      We encountered a situation where in the same cluster, large jobs benefit from mapred.fairscheduler.assignmultiple, but small jobs with small numbers of mappers do not: the mappers all clump to fully occupy just a few nodes, which causes those nodes to saturate and bottleneck. The desired behavior is to spread the job across more nodes so that a relatively small job doesn't saturate any node in the cluster.

      Testing has shown that setting mapred.fairscheduler.assignmultiple to false gives the desired behavior for small jobs, but is unnecessary for large jobs. However, since this is a cluster-wide setting, we can't properly tune.

      It'd be nice if jobs can set a param similar to mapred.fairscheduler.assignmultiple on submission to better control the task distribution of a particular job.

      1. mr-2905.txt
        11 kB
        Todd Lipcon
      2. mr-2905.txt
        10 kB
        Todd Lipcon
      3. ASF.LICENSE.NOT.GRANTED--screenshot-1.jpg
        58 kB
        Jeff Bean
      4. MR-2905.10-13-2011
        12 kB
        Jeff Bean
      5. MR-2905.patch.2
        5 kB
        Jeff Bean
      6. MR-2905.patch
        4 kB
        Jeff Bean

        Activity

          People

          • Assignee:
            Jeff Bean
            Reporter:
            Jeff Bean
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            Dates

            • Created:
              Updated:
              Resolved:

              Development