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Posted to issues@spark.apache.org by "Sandy Ryza (JIRA)" <ji...@apache.org> on 2015/01/30 00:29:34 UTC

[jira] [Created] (SPARK-5490) KMeans costs can be incorrect if tasks need to be rerun

Sandy Ryza created SPARK-5490:
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             Summary: KMeans costs can be incorrect if tasks need to be rerun
                 Key: SPARK-5490
                 URL: https://issues.apache.org/jira/browse/SPARK-5490
             Project: Spark
          Issue Type: Bug
          Components: MLlib
    Affects Versions: 1.3.0
            Reporter: Sandy Ryza
            Assignee: Sandy Ryza


KMeans uses accumulators to compute the cost of a clustering at each iteration.

Each time a ShuffleMapTask completes, it increments the accumulators at the driver.  If a task runs twice because of failures, the accumulators get incremented twice.

KMeans uses accumulators in ShuffleMapTasks.  This means that a task's cost can end up being double-counted.



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