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  1. Hadoop Common
  2. HADOOP-387

LocalJobRunner assigns duplicate mapid's

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 0.4.0
    • Fix Version/s: 0.5.0
    • Component/s: None
    • Labels:
      None
    • Environment:

      xp, cygwin, jdk1.4.2_12

      Description

      While hunting down nutch issue NUTCH-266 i discovered that id's are generated with following fragment of code:

      private String newId()

      { return Integer.toString(Math.abs(new Random().nextInt()),36); }

      and the related Javadoc:
      "
      public Random()

      Creates a new random number generator. Its seed is initialized to a value based on the current time:

      public Random()

      { this(System.currentTimeMillis()); }

      Two Random objects created within the same millisecond will have the same sequence of random numbers.

      "

      it appears that in this case there are more than one Random pobject generated at the same millisecond and id's are
      no longer unique.

        Attachments

        1. hadoop-fix-dup-id-trunk.patch
          0.7 kB
          Sami Siren
        2. hadoop-fix-dup-id-0.4.patch
          0.7 kB
          Sami Siren

          Activity

            People

            • Assignee:
              Unassigned
              Reporter:
              siren Sami Siren
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              Dates

              • Created:
                Updated:
                Resolved: