Hadoop Map/Reduce
  1. Hadoop Map/Reduce
  2. MAPREDUCE-239

Attribute to mark Mappers and Reducers as side-effect free

    Details

    • Type: Improvement Improvement
    • Status: Resolved
    • Priority: Major Major
    • Resolution: Won't Fix
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None
    • Labels:
      None

      Description

      There should be an annotation to mark Mapper and Reducer classes as side-effect free. This annotation could then be used to disable speculative execution for such classes. Furthermore, defining a class without the NoSideEffect attribute as a combiner would be a run-time error.

      @NoSideEffects
      class MyMapper extends MapReduceBase implements Mapper

      { ... }

      would declare that MyMapper may be run speculatively.

      @NoSideEffects
      class MyReducer extends MapReduceBase implements Reducer

      { ...}

      declares that MyReducer can be run speculative and as a combiner.

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          People

          • Assignee:
            Unassigned
            Reporter:
            Owen O'Malley
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            Dates

            • Created:
              Updated:
              Resolved:

              Development