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  1. Hadoop Common
  2. HADOOP-3940

Reduce often attempts in memory merge with no work

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: 0.18.0
    • Fix Version/s: 0.18.1
    • Component/s: None
    • Labels:
      None
    • Hadoop Flags:
      Reviewed

      Description

      ReduceTask.ReduceCopier.ShuffleRamManager initializes numRequiredMapOutputs to 0, so one of the predicates in ShuffleRamManager::waitForDataToMerge, numPendingRequests < numRequiredMapOutputs, is false until the first map output is fetched and false again after the last map output is fetched. The InMemFSMergeThread thread will loop busily in this state.

        Attachments

        1. 3940-1.patch
          2 kB
          Chris Douglas
        2. 3940-0.patch
          0.7 kB
          Chris Douglas

          Activity

            People

            • Assignee:
              chris.douglas Chris Douglas
              Reporter:
              chris.douglas Chris Douglas
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              Dates

              • Created:
                Updated:
                Resolved: