Hadoop Map/Reduce
  1. Hadoop Map/Reduce
  2. MAPREDUCE-2349

speed up list[located]status calls from input formats

    Details

    • Type: Improvement Improvement
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 2.4.0
    • Component/s: task
    • Labels:
      None
    • Hadoop Flags:
      Reviewed
    • Target Version/s:

      Description

      when a job has many input paths - listStatus - or the improved listLocatedStatus - calls (invoked from the getSplits() method) can take a long time. Most of the time is spent waiting for the previous call to complete and then dispatching the next call.

      This can be greatly speeded up by dispatching multiple calls at once (via executors). If the same filesystem client is used - then the calls are much better pipelined (since calls are serialized) and don't impose extra burden on the namenode while at the same time greatly reducing the latency to the client. In a simple test on non-peak hours, this resulted in the getSplits() time reducing from about 3s to about 0.5s.

      1. MAPREDUCE-2349.1.wip.txt
        22 kB
        Siddharth Seth
      2. MAPREDUCE-2349.2.txt
        39 kB
        Siddharth Seth
      3. MAPREDUCE-2349.3.txt
        39 kB
        Siddharth Seth
      4. MAPREDUCE-2349.4.txt
        41 kB
        Siddharth Seth
      5. MAPREDUCE-2349.5.txt
        43 kB
        Siddharth Seth

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            People

            • Assignee:
              Siddharth Seth
              Reporter:
              Joydeep Sen Sarma
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              Dates

              • Created:
                Updated:
                Resolved:

                Development