[jira] [Created] (FLINK-2361) flatMap + distict gives eroneous results for big data sets

["Andra Lungu (JIRA)" <ji...@apache.org>]

Andra Lungu created FLINK-2361:
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             Summary: flatMap + distict gives eroneous results for big data sets
                 Key: FLINK-2361
                 URL: https://issues.apache.org/jira/browse/FLINK-2361
             Project: Flink
          Issue Type: Bug
          Components: Gelly
    Affects Versions: 0.10
            Reporter: Andra Lungu


When running the simple Connected Components algorithm (currently in Gelly) on the twitter follower graph, with 1, 100 or 10000 iterations, I get the following error:

Caused by: java.lang.Exception: Target vertex '657282846' does not exist!.
	at org.apache.flink.graph.spargel.VertexCentricIteration$VertexUpdateUdfSimpleVV.coGroup(VertexCentricIteration.java:300)
	at org.apache.flink.runtime.operators.CoGroupWithSolutionSetSecondDriver.run(CoGroupWithSolutionSetSecondDriver.java:220)
	at org.apache.flink.runtime.operators.RegularPactTask.run(RegularPactTask.java:496)
	at org.apache.flink.runtime.iterative.task.AbstractIterativePactTask.run(AbstractIterativePactTask.java:139)
	at org.apache.flink.runtime.iterative.task.IterationTailPactTask.run(IterationTailPactTask.java:107)
	at org.apache.flink.runtime.operators.RegularPactTask.invoke(RegularPactTask.java:362)
	at org.apache.flink.runtime.taskmanager.Task.run(Task.java:559)
	at java.lang.Thread.run(Thread.java:722)

Now this is very bizzare as the DataSet of vertices is produced from the DataSet of edges... Which means there cannot be a an edge with an invalid target id... The method calls flatMap to isolate the src and trg ids and distinct to ensure their uniqueness.  

The algorithm works fine for smaller data sets... 





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