[jira] [Commented] (FLINK-5506) Java 8 - CommunityDetection.java:158 - java.lang.NullPointerException

["Neelesh Srinivas Salian (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-5506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15971390#comment-15971390 ] 

Neelesh Srinivas Salian commented on FLINK-5506:
------------------------------------------------

Hi, [~mcoimbra] is this still an issue?

> Java 8 - CommunityDetection.java:158 - java.lang.NullPointerException
> ---------------------------------------------------------------------
>
>                 Key: FLINK-5506
>                 URL: https://issues.apache.org/jira/browse/FLINK-5506
>             Project: Flink
>          Issue Type: Bug
>          Components: Gelly
>    Affects Versions: 1.1.4
>            Reporter: Miguel E. Coimbra
>              Labels: easyfix, newbie
>   Original Estimate: 48h
>  Remaining Estimate: 48h
>
> Reporting this here as per Vasia's advice.
> I am having the following problem while trying out the org.apache.flink.graph.library.CommunityDetection algorithm of the Gelly API (Java).
> Specs: JDK 1.8.0_102 x64
> Apache Flink: 1.1.4
> Suppose I have a very small (I tried an example with 38 vertices as well) dataset stored in a tab-separated file 3-vertex.tsv:
> #id1 id2 score
> 0    1    0
> 0    2    0
> 0    3    0
> This is just a central vertex with 3 neighbors (disconnected between themselves).
> I am loading the dataset and executing the algorithm with the following code:
> -----------------------------------------------
> // Load the data from the .tsv file.
> final DataSet<Tuple3<Long, Long, Double>> edgeTuples = env.readCsvFile(inputPath)
>                 .fieldDelimiter("\t") // node IDs are separated by spaces
>                 .ignoreComments("#")  // comments start with "%"
>                 .types(Long.class, Long.class, Double.class);
> // Generate a graph and add reverse edges (undirected).
> final Graph<Long, Long, Double> graph = Graph.fromTupleDataSet(edgeTuples, new MapFunction<Long, Long>() {
>             private static final long serialVersionUID = 8713516577419451509L;
>             public Long map(Long value) {
>                 return value;
>             }
>         },
> env).getUndirected();
> // CommunityDetection parameters.
> final double hopAttenuationDelta = 0.5d;
> final int iterationCount = 10;
> // Prepare and trigger the execution.
> DataSet<Vertex<Long, Long>> vs = graph.run(new org.apache.flink.graph.library.CommunityDetection<Long>(iterationCount, hopAttenuationDelta)).getVertices();
> vs.print();
> ​-----------------------------------------------​
> ​Running this code throws the following exception​ (check the bold line):
> ​org.apache.flink.runtime.client.JobExecutionException: Job execution failed.
>     at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$8.apply$mcV$sp(JobManager.scala:805)
>     at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$8.apply(JobManager.scala:751)
>     at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$8.apply(JobManager.scala:751)
>     at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
>     at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
>     at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:41)
>     at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:401)
>     at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
>     at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.pollAndExecAll(ForkJoinPool.java:1253)
>     at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1346)
>     at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
>     at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
> Caused by: java.lang.NullPointerException
>     at org.apache.flink.graph.library.CommunityDetection$VertexLabelUpdater.updateVertex(CommunityDetection.java:158)
>     at org.apache.flink.graph.spargel.ScatterGatherIteration$GatherUdfSimpleVV.coGroup(ScatterGatherIteration.java:389)
>     at org.apache.flink.runtime.operators.CoGroupWithSolutionSetSecondDriver.run(CoGroupWithSolutionSetSecondDriver.java:218)
>     at org.apache.flink.runtime.operators.BatchTask.run(BatchTask.java:486)
>     at org.apache.flink.runtime.iterative.task.AbstractIterativeTask.run(AbstractIterativeTask.java:146)
>     at org.apache.flink.runtime.iterative.task.IterationTailTask.run(IterationTailTask.java:107)
>     at org.apache.flink.runtime.operators.BatchTask.invoke(BatchTask.java:351)
>     at org.apache.flink.runtime.taskmanager.Task.run(Task.java:642)
>     at java.lang.Thread.run(Thread.java:745)​
> ​After a further look, I set a breakpoint (Eclipse IDE debugging) at the line in bold:
> org.apache.flink.graph.library.CommunityDetection.java (source code accessed automatically by Maven)
> // find the highest score of maxScoreLabel
> double highestScore = labelsWithHighestScore.get(maxScoreLabel);​
> ​- maxScoreLabel has the value 3.​
> - labelsWithHighestScore was initialized as: Map<Long, Double> labelsWithHighestScore = new TreeMap<>();
> - labelsWithHighestScore is a TreeMap<Long, Double> and has the values:
> {0=0.0}
> null
> null
> [0=0.0]
> null
> 1​
> ​It seems that the value 3 should have been added to that ​labelsWithHighestScore some time during execution, but because it wasn't, an exception is thrown.
> In the mailing list, Vasia speculates that the problem is that the implementation assumes that labelsWithHighestScores contains the vertex itself as initial label.



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