Hi,
I believe it's because you're trying to use a Function of an RDD, in an RDD,
which is not possible. Instead of using a
`Function<JavaRDD<Float>>`, could you try Function<Float>, and
`public Void call(Float arg0) throws Exception { `
and
`System.out.println(arg0)`
instead. I'm not perfectly sure of the semantics in Java, but this should be
what you're actually trying to do.
Best,
Burak
----- Original Message -----
From: "Filip Andrei" <andreis.fi...@gmail.com>
To: u...@spark.incubator.apache.org
Sent: Thursday, September 18, 2014 6:57:21 AM
Subject: Odd error when using a rdd map within a stream map
here i wrote a simpler version of the code to get an understanding of how it
works:
final List<NeuralNet> nns = new ArrayList<NeuralNet>();
for(int i = 0; i < numberOfNets; i++){
nns.add(NeuralNet.createFrom(...));
}
final JavaRDD<NeuralNet> nnRdd = sc.parallelize(nns);
JavaDStream<Float> results = rndLists.flatMap(new
FlatMapFunction<Map<String,Object>, Float>() {
@Override
public Iterable<Float> call(Map<String, Object> input)
throws Exception {
Float f = nnRdd.map(new Function<NeuralNet, Float>() {
@Override
public Float call(NeuralNet nn) throws Exception {
return 1.0f;
}
}).reduce(new Function2<Float, Float, Float>() {
@Override
public Float call(Float left, Float right) throws Exception {
return left + right;
}
});
return Arrays.asList(f);
}
});
results.print();
This works as expected and print() simply shows the number of neural nets i
have
If instead a print() i use
results.foreach(new Function<JavaRDD<Float>, Void>() {
@Override
public Void call(JavaRDD<Float> arg0) throws Exception {
for(Float f : arg0.collect()){
System.out.println(f);
}
return null;
}
});
It fails with the following exception
org.apache.spark.SparkException: Job aborted due to stage failure: Task
1.0:0 failed 1 times, most recent failure: Exception failure in TID 1 on
host localhost: java.lang.NullPointerException
org.apache.spark.rdd.RDD.map(RDD.scala:270)
This is weird to me since the same code executes as expected in one case and
doesn't in the other, any idea what's going on here ?
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