[jira] [Created] (FLINK-2189) NullPointerException in MutableHashTable

["Till Rohrmann (JIRA)" <ji...@apache.org>]

Till Rohrmann created FLINK-2189:
------------------------------------

             Summary: NullPointerException in MutableHashTable
                 Key: FLINK-2189
                 URL: https://issues.apache.org/jira/browse/FLINK-2189
             Project: Flink
          Issue Type: Bug
          Components: Core
            Reporter: Till Rohrmann


[~Felix Neutatz] reported a {{NullPointerException}} in the {{MutableHashTable}} when running the {{ALS}} algorithm. The stack trace is the following:
{code}
Caused by: java.lang.NullPointerException
	at org.apache.flink.runtime.operators.hash.HashPartition.spillPartition(HashPartition.java:310)
	at org.apache.flink.runtime.operators.hash.MutableHashTable.spillPartition(MutableHashTable.java:1094)
	at org.apache.flink.runtime.operators.hash.MutableHashTable.insertBucketEntry(MutableHashTable.java:927)
	at org.apache.flink.runtime.operators.hash.MutableHashTable.buildTableFromSpilledPartition(MutableHashTable.java:783)
	at org.apache.flink.runtime.operators.hash.MutableHashTable.prepareNextPartition(MutableHashTable.java:508)
	at org.apache.flink.runtime.operators.hash.MutableHashTable.nextRecord(MutableHashTable.java:544)
	at org.apache.flink.runtime.operators.hash.NonReusingBuildFirstHashMatchIterator.callWithNextKey(NonReusingBuildFirstHashMatchIterator.java:104)
	at org.apache.flink.runtime.operators.MatchDriver.run(MatchDriver.java:173)
	at org.apache.flink.runtime.operators.RegularPactTask.run(RegularPactTask.java:496)
	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:745)
{code}

He produced this error on his local machine with the following code:
{code}
implicit val env = ExecutionEnvironment.getExecutionEnvironment

    val links = MovieLensUtils.readLinks(movieLensDir + "links.csv")
    val movies = MovieLensUtils.readMovies(movieLensDir + "movies.csv")
    val ratings = MovieLensUtils.readRatings(movieLensDir + "ratings.csv")
    val tags = MovieLensUtils.readTags(movieLensDir + "tags.csv")
     
     
    val ratingMatrix =  ratings.map { r => (r.userId.toInt, r.movieId.toInt, r.rating) }

    val testMatrix =  ratings.map { r => (r.userId.toInt, r.movieId.toInt) }

    val als = ALS()
       .setIterations(10)
       .setNumFactors(10)
       .setBlocks(150) 
     
    als.fit(ratingMatrix)

    val result = als.predict(testMatrix)
     
    result.print

    val risk = als.empiricalRisk(ratingMatrix).collect().apply(0)
    println("Empirical risk: " + risk) 

    env.execute()
{code}



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