Срещам много странен проблем на Spark относно сериализацията. Кодът е както следва:
class PLSA(val sc : SparkContext, val numOfTopics : Int) extends Serializable
{
def infer(document: RDD[Document]): RDD[DocumentParameter] = {
val docs = documents.map(doc => DocumentParameter(doc, numOfTopics))
docs
}
}
където документът е дефиниран като:
class Document(val tokens: SparseVector[Int]) extends Serializable
и DocumentParameter е:
class DocumentParameter(val document: Document, val theta: Array[Float]) extends Serializable
object DocumentParameter extends Serializable
{
def apply(document: Document, numOfTopics: Int) = new DocumentParameter(document,
Array.ofDim[Float](numOfTopics))
}
SparseVectors е сериализиращ се клас в breeze.linalg.SparseVector
.
Това е проста процедура за карта и всички класове могат да се сериализират, но получавам това изключение:
org.apache.spark.SparkException: Task not serializable
Но когато премахна параметъра numOfTopics
, това е:
object DocumentParameter extends Serializable
{
def apply(document: Document) = new DocumentParameter(document,
Array.ofDim[Float](10))
}
и го наречете така:
val docs = documents.map(DocumentParameter.apply)
и изглежда добре.
Тип Int не може ли да се сериализира? Но виждам, че някакъв код е написан така.
Не съм сигурен как да поправя тази грешка.
#АКТУАЛИЗИРАНО#:
Благодаря ти @samthebest. Ще добавя повече подробности за него.
stack trace:
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:1242)
at org.apache.spark.rdd.RDD.map(RDD.scala:270)
at com.topicmodel.PLSA.infer(PLSA.scala:13)
at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:30)
at $iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:35)
at $iwC$$iwC$$iwC$$iwC.<init>(<console>:37)
at $iwC$$iwC$$iwC.<init>(<console>:39)
at $iwC$$iwC.<init>(<console>:41)
at $iwC.<init>(<console>:43)
at <init>(<console>:45)
at .<init>(<console>:49)
at .<clinit>(<console>)
at .<init>(<console>:7)
at .<clinit>(<console>)
at $print(<console>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.apache.spark.repl.SparkIMain$ReadEvalPrint.call(SparkIMain.scala:789)
at org.apache.spark.repl.SparkIMain$Request.loadAndRun(SparkIMain.scala:1062)
at org.apache.spark.repl.SparkIMain.loadAndRunReq$1(SparkIMain.scala:615)
at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:646)
at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:610)
at org.apache.spark.repl.SparkILoop.reallyInterpret$1(SparkILoop.scala:814)
at org.apache.spark.repl.SparkILoop.interpretStartingWith(SparkILoop.scala:859)
at org.apache.spark.repl.SparkILoop.command(SparkILoop.scala:771)
at org.apache.spark.repl.SparkILoop.processLine$1(SparkILoop.scala:616)
at org.apache.spark.repl.SparkILoop.innerLoop$1(SparkILoop.scala:624)
at org.apache.spark.repl.SparkILoop.loop(SparkILoop.scala:629)
at org.apache.spark.repl.SparkILoop$$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$.main(Main.scala:31)
at org.apache.spark.repl.Main.main(Main.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.apache.spark.deploy.SparkSubmit$.launch(SparkSubmit.scala:328)
at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:75)
at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
Caused by: java.io.NotSerializableException: org.apache.spark.SparkContext
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at org.apache.spark.serializer.JavaSerializationStream.writeObject(JavaSerializer.scala:42)
at org.apache.spark.serializer.JavaSerializerInstance.serialize(JavaSerializer.scala:73)
at org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:164)
... 46 more
Тъй като проследяването на стека дава обща информация за изключение, аз го премахнах.
Пускам кода в spark-shell.
// suppose I have get RDD[Document] for docs
val numOfTopics = 100
val plsa = new PLSA(sc, numOfTopics)
val docPara = plsa.infer(docs)
Бихте ли ми дали някои уроци или съвети за сериализуемо?