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  1. Hadoop Map/Reduce
  2. MAPREDUCE-5907

Improve getSplits() performance for fs implementations that can utilize performance gains from recursive listing



    • Type: Improvement
    • Status: Patch Available
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 2.4.0
    • Fix Version/s: None
    • Component/s: client
    • Labels:


      FileInputFormat (both mapreduce and mapred implementations) use recursive listing while calculating splits. They however do this by doing listing level by level. That means to discover files in /foo/bar means they do listing at /foo/bar first to get the immediate children, then make the same call on all immediate children for /foo/bar to discover their immediate children and so on. This doesn't scale well for object store based fs implementations like s3 and swift because every listStatus call ends up being a webservice call to backend. In cases where large number of files are considered for input, this makes getSplits() call slow.

      This patch adds a new set of recursive list apis that gives opportunity to the fs implementations to optimize. The behavior remains the same for other implementations (that is a default implementation is provided for other fs so they don't have to implement anything new). However for objectstore based fs implementations it provides a simple change to include recursive flag as true (as shown in the patch) to improve listing performance.


        1. MAPREDUCE-5907.patch
          11 kB
          Sumit Kumar
        2. MAPREDUCE-5907-2.patch
          33 kB
          Sumit Kumar
        3. MAPREDUCE-5907-3.patch
          33 kB
          Sumit Kumar

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              • Assignee:
                ksumit Sumit Kumar
                ksumit Sumit Kumar
              • Votes:
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