I'm trying to use Neo4j with Apache Spark Streaming but I am finding
serializability as an issue.
Basically, I want Apache Spark to parse and bundle my data in real time.
After, the data has been bundled it should be stored in the database,
Neo4j. However, I am getting this error:
org.apache.spark.SparkException: Task not serializable
at
org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:166)
at org.apache.spark.util.ClosureCleaner$.clean(ClosureCleaner.scala:158)
at org.apache.spark.SparkContext.clean(SparkContext.scala:1264)
at
org.apache.spark.api.java.JavaRDDLike$class.foreach(JavaRDDLike.scala:297)
at org.apache.spark.api.java.JavaPairRDD.foreach(JavaPairRDD.scala:45)
at twoGrams.Main$4.call(Main.java:102)
at twoGrams.Main$4.call(Main.java:1)
at
org.apache.spark.streaming.api.java.JavaDStreamLike$$anonfun$foreachRDD$2.apply(JavaDStreamLike.scala:282)
at
org.apache.spark.streaming.api.java.JavaDStreamLike$$anonfun$foreachRDD$2.apply(JavaDStreamLike.scala:282)
at
org.apache.spark.streaming.dstream.ForEachDStream$$anonfun$1.apply$mcV$sp(ForEachDStream.scala:41)
at
org.apache.spark.streaming.dstream.ForEachDStream$$anonfun$1.apply(ForEachDStream.scala:40)
at
org.apache.spark.streaming.dstream.ForEachDStream$$anonfun$1.apply(ForEachDStream.scala:40)
at scala.util.Try$.apply(Try.scala:161)
at org.apache.spark.streaming.scheduler.Job.run(Job.scala:32)
at
org.apache.spark.streaming.scheduler.JobScheduler$JobHandler.run(JobScheduler.scala:172)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)Caused by:
java.io.NotSerializableException: org.neo4j.kernel.EmbeddedGraphDatabase
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1183)
at
java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177)
at
java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177)
at
java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508)
at
java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:347)
at
org.apache.spark.serializer.JavaSerializationStream.writeObject(JavaSerializer.scala:42)
at
org.apache.spark.serializer.JavaSerializerInstance.serialize(JavaSerializer.scala:73)
at
org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:164)
... 17 more
Here is my code:
output a stream of type: JavaPairDStream<String, ArrayList<String>>
output.foreachRDD(
new
Function2<JavaPairRDD<String,ArrayList<String>>,Time,Void>(){
@Override
public Void call(
JavaPairRDD<String, ArrayList<String>> arg0,
Time arg1) throws Exception {
// TODO Auto-generated method stub
arg0.foreach(
new
VoidFunction<Tuple2<String,ArrayList<String>>>(){
@Override
public void call(
Tuple2<String, ArrayList<String>>
arg0)
throws Exception {
// TODO Auto-generated method stub
try( Transaction tx =
graphDB.beginTx()){
if(Neo4jOperations.getHMacFromValue(graphDB, arg0._1)!=null)
System.out.println("Alread in
Database:" + arg0._1);
else{
Neo4jOperations.createHMac(graphDB, arg0._1);
}
tx.success();
}
}
});
return null;
}
});
Neo4jOperations Class:
public class Neo4jOperations{
public static Node getHMacFromValue(GraphDatabaseService graphDB,String value){
try(ResourceIterator<Node>
HMacs=graphDB.findNodesByLabelAndProperty(DynamicLabel.label("HMac"), "value",
value).iterator()){
return HMacs.next();
}
}
public static void createHMac(GraphDatabaseService graphDB,String value){
Node HMac=graphDB.createNode(DynamicLabel.label("HMac"));
HMac.setProperty("value", value);
HMac.setProperty("time", new
SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime()));
}}
I know that I have to Serialize the class Neo4jOperations, but I'm able to
figure out how. Or is there any other way to achieve this?
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