Akka Cluster custom serializer: - serialization

Question

I am using Akka Cluster to achieve some redundancy and remove single points of failure in my java application. However, I am having some problems with the serialization of the messages when sending them from one machine to another.
I am sending a java object that doesn't implement Serializable. Because of that, I need to use my own serializer and luckily the object provides a serialization method using Kryo. So, following this guide I have created my own akka serializer extending JSerializer:
import akka.serialization.JSerializer;
public class MyObjectClusterSerializer extends JSerializer {
public int identifier() {
return 66666;
}
public boolean includeManifest() {
return false;
}
public byte[] toBinary(Object obj) {
MyObject myObject = (MyObject) obj;
byte[] bytes = null;
try {
bytes = MyObjectHelper.serialize(myObject);
} catch (SerializationException e) {
}
return bytes;
}
#Override
public Object fromBinaryJava(byte[] arg0, Class<?> arg1) {
MyObject myObject = null;
try {
myObject = MyObjectHelper.deserialize(arg0);
} catch (DeserializationException e) {
}
return myObject;
}
}
The code is pretty straightforward and I don't believe that is the problem. Then I add the serializer and the serializer binding to my configuration:
serializers {
myobject = "com.my.awesome.project.MyObjectClusterSerializer"
}
serialization-bindings {
"com.my.awesome.project.MyObject" = myobject
}
When I am running a single node I don't have any issues (obviously because I am not serializing anything...). However in cluster mode I keep getting these exceptions:
2014-08-04 01:45:27,498 ERROR [MyApp-akka.actor.default-dispatcher-16] - Slf4jLogger$$anonfun$receive$1$$anonfun$applyOrElse$1.apply$mcV$sp (Slf4jLogger.scala:66) - Transient association error (association remains live)
java.io.NotSerializableException: com.my.awesome.project.MyObject
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1183) ~[?:1.7.0_60]
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547) ~[?:1.7.0_60]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508) ~[?:1.7.0_60]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431) ~[?:1.7.0_60]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177) ~[?:1.7.0_60]
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:347) ~[?:1.7.0_60]
at akka.serialization.JavaSerializer$$anonfun$toBinary$1.apply$mcV$sp(Serializer.scala:129) ~[akka-actor_2.11-2.3.4.jar:?]
at akka.serialization.JavaSerializer$$anonfun$toBinary$1.apply(Serializer.scala:129) ~[akka-actor_2.11-2.3.4.jar:?]
at akka.serialization.JavaSerializer$$anonfun$toBinary$1.apply(Serializer.scala:129) ~[akka-actor_2.11-2.3.4.jar:?]
at scala.util.DynamicVariable.withValue(DynamicVariable.scala:58) ~[scala-library-2.11.1.jar:?]
at akka.serialization.JavaSerializer.toBinary(Serializer.scala:129) ~[akka-actor_2.11-2.3.4.jar:?]
at akka.remote.serialization.MessageContainerSerializer.serializeSelection(MessageContainerSerializer.scala:36) ~[akka-remote_2.11-2.3.4.jar:?]
at akka.remote.serialization.MessageContainerSerializer.toBinary(MessageContainerSerializer.scala:25) ~[akka-remote_2.11-2.3.4.jar:?]
at akka.remote.MessageSerializer$.serialize(MessageSerializer.scala:36) ~[akka-remote_2.11-2.3.4.jar:?]
at akka.remote.EndpointWriter$$anonfun$serializeMessage$1.apply(Endpoint.scala:845) ~[akka-remote_2.11-2.3.4.jar:?]
at akka.remote.EndpointWriter$$anonfun$serializeMessage$1.apply(Endpoint.scala:845) ~[akka-remote_2.11-2.3.4.jar:?]
at scala.util.DynamicVariable.withValue(DynamicVariable.scala:58) ~[scala-library-2.11.1.jar:?]
at akka.remote.EndpointWriter.serializeMessage(Endpoint.scala:844) ~[akka-remote_2.11-2.3.4.jar:?]
at akka.remote.EndpointWriter.writeSend(Endpoint.scala:747) ~[akka-remote_2.11-2.3.4.jar:?]
at akka.remote.EndpointWriter$$anonfun$4.applyOrElse(Endpoint.scala:722) ~[akka-remote_2.11-2.3.4.jar:?]
at akka.actor.Actor$class.aroundReceive(Actor.scala:465) ~[akka-actor_2.11-2.3.4.jar:?]
at akka.remote.EndpointActor.aroundReceive(Endpoint.scala:415) ~[akka-remote_2.11-2.3.4.jar:?]
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516) [akka-actor_2.11-2.3.4.jar:?]
at akka.actor.ActorCell.invoke(ActorCell.scala:487) [akka-actor_2.11-2.3.4.jar:?]
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:238) [akka-actor_2.11-2.3.4.jar:?]
at akka.dispatch.Mailbox.run(Mailbox.scala:220) [akka-actor_2.11-2.3.4.jar:?]
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:393) [akka-actor_2.11-2.3.4.jar:?]
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) [scala-library-2.11.1.jar:?]
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) [scala-library-2.11.1.jar:?]
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) [scala-library-2.11.1.jar:?]
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) [scala-library-2.11.1.jar:?]
And to me that means it is not able to figure out what serializer to use and it's actually using the generic Java one. Also, I don't know if it's related but I am wrapping my message with a ConsistentHashableEnvelope because I am sending it to a cluster-aware consistent hashing group.
Any help to make this thing work? Am I missing something?

Answer 1

Akka selects serializer once by message class (see stack trace). In your case akka correctly uses JavaSerializer because base message has ConsistentHashableEnvelope type and applies this serializer to all fields (message and hashKey).
To solve your task just create serlializer for ConsistentHashableEnvelope and use MyObjectClusterSerializer only if message field has MyObject type and JavaSerializer in other cases