bq. I'm on version 2.10 for spark
The above is Scala version.
Can you give us the Spark version ?
Thanks
On Mon, Apr 4, 2016 at 2:36 PM, mpawashe <mpawa...@gmail.com> wrote:
> Hi all,
>
> I am using Spark Streaming API (I'm on version 2.10 for spark and
> streaming), and I am running into a function serialization issue that I do
> not run into when using Spark in batch (non-streaming) mode.
>
> If I wrote code like this:
>
> def run(): Unit = {
> val newStream = stream.map(x => { x + " foo " })
> // ...
> }
>
> everything works fine.. But if I try it like this:
>
> def transform(x: String): String = { x + " foo " }
>
> def run(): Unit = {
> val newStream = stream.map(transform)
> // ...
> }
>
> ..the program fails being unable to serialize the closure (which when
> passing a method to a function that expects a closure, it should be
> auto-converted to my understanding).
>
> However it works fine if I declare a closure inside run() and use that like
> so:
>
> val transform = (x: String) => { x + " foo " }
>
> If it's declared outside of run(), however, it will also crash.
>
> This is an example stack trace of the error I'm running into. This can be a
> hassle to debug so I hope I wouldn't have to get around this by having to
> use a local closure/function every time. Thanks for any help in advance.
>
> org.apache.spark.SparkException: Task not serializable
> at
>
> org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:304)
> at
>
> org.apache.spark.util.ClosureCleaner$.org$apache$spark$util$ClosureCleaner$$clean(ClosureCleaner.scala:294)
> at
> org.apache.spark.util.ClosureCleaner$.clean(ClosureCleaner.scala:122)
> at org.apache.spark.SparkContext.clean(SparkContext.scala:2030)
> at
>
> org.apache.spark.streaming.dstream.DStream$$anonfun$map$1.apply(DStream.scala:528)
> at
>
> org.apache.spark.streaming.dstream.DStream$$anonfun$map$1.apply(DStream.scala:528)
> at
>
> org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:147)
> at
>
> org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:108)
> at org.apache.spark.SparkContext.withScope(SparkContext.scala:709)
> at
>
> org.apache.spark.streaming.StreamingContext.withScope(StreamingContext.scala:266)
> at
> org.apache.spark.streaming.dstream.DStream.map(DStream.scala:527)
> at com.my.cool.app.MyClass.run(MyClass.scala:90)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
> at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
> at java.lang.reflect.Method.invoke(Unknown Source)
> at
> org.apache.spark.deploy.worker.DriverWrapper$.main(DriverWrapper.scala:58)
> at
> org.apache.spark.deploy.worker.DriverWrapper.main(DriverWrapper.scala)
> Caused by: java.io.NotSerializableException: Graph is unexpectedly null
> when
> DStream is being serialized.
> Serialization stack:
>
> at
>
> org.apache.spark.serializer.SerializationDebugger$.improveException(SerializationDebugger.scala:40)
> at
>
> org.apache.spark.serializer.JavaSerializationStream.writeObject(JavaSerializer.scala:47)
> at
>
> org.apache.spark.serializer.JavaSerializerInstance.serialize(JavaSerializer.scala:84)
> at
>
> org.apache.spark.util.ClosureCleaner$.ensureSerializable(ClosureCleaner.scala:301)
> ... 20 more
>
>
>
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