Carsten Brandt created FLINK-1587:
-------------------------------------
Summary: coGroup throws NoSuchElementException on iterator.next()
Key: FLINK-1587
URL: https://issues.apache.org/jira/browse/FLINK-1587
Project: Flink
Issue Type: Bug
Components: Gelly
Environment: flink-0.8.0-SNAPSHOT
Reporter: Carsten Brandt
I am receiving the following exception when running a simple job that extracts
outdegree from a graph using Gelly. It is currently only failing on the cluster
and I am not able to reproduce it locally. Will try that the next days.
{{{
02/20/2015 02:27:02: Map (Map at count(GraphUtils.java:26)) (36/64) switched
to RUNNING
02/20/2015 02:27:02: CoGroup (CoGroup at inDegrees(Graph.java:675)) (5/64)
switched to FAILED
java.util.NoSuchElementException
at java.util.Collections$EmptyIterator.next(Collections.java:3006)
at flink.graphs.Graph$CountNeighborsCoGroup.coGroup(Graph.java:665)
at
org.apache.flink.runtime.operators.CoGroupDriver.run(CoGroupDriver.java:130)
at
org.apache.flink.runtime.operators.RegularPactTask.run(RegularPactTask.java:493)
at
org.apache.flink.runtime.operators.RegularPactTask.invoke(RegularPactTask.java:360)
at
org.apache.flink.runtime.execution.RuntimeEnvironment.run(RuntimeEnvironment.java:257)
at java.lang.Thread.run(Thread.java:745)
02/20/2015 02:27:02: Job execution switched to status FAILING
...
}}}
The error occurs in Gellys Graph.java at this line:
https://github.com/apache/flink/blob/a51c02f6e8be948d71a00c492808115d622379a7/flink-staging/flink-gelly/src/main/java/org/apache/flink/graph/Graph.java#L636
Is there any valid case where a coGroup Iterator may be empty? As far as I see
there is a bug somewhere.
I'd like to write a test case for this to reproduce the issue. Where can I put
such a test?
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