import org.apache.spark.mllib.recommendation.ALS import org.apache.spark.mllib.recommendation.Rating
// Load and parse the data val data = sc.textFile("/path/CFReady.txt") val ratings = data.map(_.split('\t') match { case Array(user, item, rate) => Rating(user.toInt, item.toInt, rate.toDouble) }) // Build the recommendation model using ALS val rank = 50 val numIterations = 100 val model = ALS.train(ratings, rank, numIterations, 0.10) // Evaluate the model on rating data val usersProducts = ratings.map { case Rating(user, product, rate) => (user, product) } val predictions = model.predict(usersProducts).map { case Rating(user, product, rate) => ((user, product), rate) } val ratesAndPreds = ratings.map { case Rating(user, product, rate) => ((user, product), rate) }.join(predictions) val MSE = ratesAndPreds.map { case ((user, product), (r1, r2)) => val err = (r1 - r2) err * err }.mean() println("Mean Squared Error = " + MSE) val pw = new PrintWriter(new File("/path/CFOutput.txt")) ratesAndPreds.foreach(pw.println) } Hi, Consider the highlighted code, I am trying to write the output of ratesAndPreds array on to the disk. But I get error 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:1242) at org.apache.spark.rdd.RDD.foreach(RDD.scala:758) at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:36) at $iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:41) at $iwC$$iwC$$iwC$$iwC.<init>(<console>:43) at $iwC$$iwC$$iwC.<init>(<console>:45) at $iwC$$iwC.<init>(<console>:47) at $iwC.<init>(<console>:49) at <init>(<console>:51) at .<init>(<console>:55) at .<clinit>(<console>) at .<init>(<console>:7) at .<clinit>(<console>) at $print(<console>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.apache.spark.repl.SparkIMain$ReadEvalPrint.call(SparkIMain.scala:789) at org.apache.spark.repl.SparkIMain$Request.loadAndRun(SparkIMain.scala:1062) at org.apache.spark.repl.SparkIMain.loadAndRunReq$1(SparkIMain.scala:615) at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:646) at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:610) at org.apache.spark.repl.SparkILoop.reallyInterpret$1(SparkILoop.scala:814) at org.apache.spark.repl.SparkILoop.interpretStartingWith(SparkILoop.scala:859) at org.apache.spark.repl.SparkILoop.command(SparkILoop.scala:771) at org.apache.spark.repl.SparkILoop.processLine$1(SparkILoop.scala:616) at org.apache.spark.repl.SparkILoop.innerLoop$1(SparkILoop.scala:624) at org.apache.spark.repl.SparkILoop.loop(SparkILoop.scala:629) at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply$mcZ$sp(SparkILoop.scala:954) at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply(SparkILoop.scala:902) at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply(SparkILoop.scala:902) at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135) at org.apache.spark.repl.SparkILoop.process(SparkILoop.scala:902) at org.apache.spark.repl.SparkILoop.process(SparkILoop.scala:997) at org.apache.spark.repl.Main$.main(Main.scala:31) at org.apache.spark.repl.Main.main(Main.scala) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.apache.spark.deploy.SparkSubmit$.launch(SparkSubmit.scala:328) at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:75) at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala) Caused by: java.io.NotSerializableException: java.io.PrintWriter 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.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.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.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) ... 45 more I am very new to Spark and Scala, can somebody please guide me here? Thanks, Saurabh ________________________________ This e-mail, including accompanying communications and attachments, is strictly confidential and only for the intended recipient. Any retention, use or disclosure not expressly authorised by Markit is prohibited. This email is subject to all waivers and other terms at the following link: http://www.markit.com/en/about/legal/email-disclaimer.page Please visit http://www.markit.com/en/about/contact/contact-us.page? for contact information on our offices worldwide. MarkitSERV Limited has its registered office located at Level 4, Ropemaker Place, 25 Ropemaker Street, London, EC2Y 9LY and is authorized and regulated by the Financial Conduct Authority with registration number 207294