Great! Let us know if you need help.
-Vasia.
On 17 January 2017 at 10:30, Miguel Coimbra <miguel.e.coim...@gmail.com>
wrote:
> Hello Vasia,
>
> I am going to look into this.
> Hopefully I will contribute to the implementation and documentation.
>
> Regards,
>
> ---------- Forwarded message ----------
> From: Vasiliki Kalavri <vasilikikala...@gmail.com>
> To: user@flink.apache.org
> Cc:
> Date: Sun, 15 Jan 2017 18:01:41 +0100
> Subject: Re: Apache Flink 1.1.4 - Java 8 - CommunityDetection.java:158 -
> java.lang.NullPointerException
> Hi Miguel,
>
> this is a bug, thanks a lot for reporting! I think the problem is that the
> implementation assumes that labelsWithHighestScores contains the vertex
> itself as initial label.
>
> Could you please open a JIRA ticket for this and attach your code and data
> as an example to reproduce? We should also improve the documentation for
> this library method. I see that you are initializing vertex values and you
> have called getUndirected(), but the library method already does both of
> these operations internally.
>
> Cheers,
> -Vasia.
>
> On 13 January 2017 at 17:12, Miguel Coimbra <miguel.e.coim...@gmail.com>
> wrote:
> Hello,
>
> If I missed the answer to this or some essential step of the
> documentation, please do tell.
> 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 with 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$$anonfun$hand
> leMessage$1$$anonfun$applyOrElse$8.apply$mcV$sp(JobManager.scala:805)
> at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$hand
> leMessage$1$$anonfun$applyOrElse$8.apply(JobManager.scala:751)
> at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$hand
> leMessage$1$$anonfun$applyOrElse$8.apply(JobManager.scala:751)
> at scala.concurrent.impl.Future$PromiseCompletingRunnable.lifte
> dTree1$1(Future.scala:24)
> at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(F
> uture.scala:24)
> at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:41)
> at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.
> exec(AbstractDispatcher.scala:401)
> at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.j
> ava:260)
> at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.pollAndExec
> All(ForkJoinPool.java:1253)
> at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(For
> kJoinPool.java:1346)
> at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPoo
> l.java:1979)
> at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinW
> orkerThread.java:107)
>
> *Caused by: java.lang.NullPointerException at
> org.apache.flink.graph.library.CommunityDetection$VertexLabelUpdater.updateVertex(CommunityDetection.java:158)*
> at org.apache.flink.graph.spargel.ScatterGatherIteration$Gather
> UdfSimpleVV.coGroup(ScatterGatherIteration.java:389)
> at org.apache.flink.runtime.operators.CoGroupWithSolutionSetSec
> ondDriver.run(CoGroupWithSolutionSetSecondDriver.java:218)
> at org.apache.flink.runtime.operators.BatchTask.run(BatchTask.j
> ava:486)
> at org.apache.flink.runtime.iterative.task.AbstractIterativeTas
> k.run(AbstractIterativeTask.java:146)
> at org.apache.flink.runtime.iterative.task.IterationTailTask.ru
> n(IterationTailTask.java:107)
> at org.apache.flink.runtime.operators.BatchTask.invoke(BatchTas
> k.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.
>
> If anyone is able to shed light on the issue it would be great - what
> might be causing it, am I doing something clearly wrong, or has this been
> fixed in a another version?
>
> Thank you very much,
>
> Best regards,
>
> Miguel E. Coimbra
> Email: miguel.e.coim...@gmail.com <miguel.e.coim...@ist.utl.pt>
> Skype: miguel.e.coimbra
>
