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  1. Hadoop Map/Reduce
  2. MAPREDUCE-7282

MR v2 commit algorithm should be deprecated and not the default

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 3.3.0, 3.2.1, 3.1.3, 3.3.1
    • Fix Version/s: None
    • Component/s: mrv2
    • Labels:
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      Description

      The v2 MR commit algorithm moves files from the task attempt dir into the dest dir on task commit -one by one

      It is therefore not atomic

      1. if a task commit fails partway through and another task attempt commits -unless exactly the same filenames are used, output of the first attempt may be included in the final result
      2. if a worker partitions partway through task commit, and then continues after another attempt has committed, it may partially overwrite the output -even when the filenames are the same

      Both MR and spark assume that task commits are atomic. Either they need to consider that this is not the case, we add a way to probe for a committer supporting atomic task commit, and the engines both add handling for task commit failures (probably fail job)

      Better: we remove this as the default, maybe also warn when it is being used

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              • Assignee:
                Unassigned
                Reporter:
                stevel@apache.org Steve Loughran
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                Dates

                • Created:
                  Updated: