Getting java.io.IOException: unsupported type / corrupted stream

Question

I am sporadically getting the following exception:
(Wrapped) java.io.IOException: unsupported type / corrupted stream
     at com.tangosol.util.ExternalizableHelper.readObject(ExternalizableHelper.java:2162)
     at com.tangosol.util.ExternalizableHelper.readMap(ExternalizableHelper.java:1557)
     at com.tsysa.risk.SyncpointController.readExternal(SyncpointController.java:262)
     at com.tangosol.util.ExternalizableHelper.readExternalizableLite(ExternalizableHelper.java:1908)
     at com.tangosol.util.ExternalizableHelper.readObject(ExternalizableHelper.java:2199)
     at com.tangosol.util.ExternalizableHelper.fromBinary(ExternalizableHelper.java:205)
     at com.tangosol.coherence.component.util.daemon.queueProcessor.service.DistributedCache$ConverterFromBinary.convert(DistributedCache.CDB:4)
     at com.tangosol.util.ConverterCollections$ConverterMap.put(ConverterCollections.java:1317)
     at com.tangosol.coherence.component.util.daemon.queueProcessor.service.DistributedCache$ViewMap.put(DistributedCache.CDB:1)
     at com.tangosol.coherence.component.util.SafeNamedCache.put(SafeNamedCache.CDB:1)
     at test.SyncpointController.updateStateInCache(SyncpointController.java:151) 
     at test.SyncpointController.onMapEvent(SyncpointController.java:121)
     at com.tangosol.util.MultiplexingMapListener.entryUpdated(MultiplexingMapListener.java:41)
     at com.tangosol.util.MapEvent.dispatch(MapEvent.java:195)
     at com.tangosol.util.MapEvent.dispatch(MapEvent.java:164)
     at com.tangosol.util.MapListenerSupport.fireEvent(MapListenerSupport.java:556)
     at com.tangosol.coherence.component.util.SafeNamedCache.translateMapEvent(SafeNamedCache.CDB:7)
     at com.tangosol.coherence.component.util.SafeNamedCache.entryUpdated(SafeNamedCache.CDB:1)
     at com.tangosol.util.MapEvent.dispatch(MapEvent.java:195)
     at com.tangosol.coherence.component.util.daemon.queueProcessor.service.DistributedCache$ViewMap$ProxyListener.dispatch(DistributedCache.CDB:22)
     at com.tangosol.coherence.component.util.daemon.queueProcessor.service.DistributedCache$ViewMap$ProxyListener.entryUpdated(DistributedCache.CDB:1)
     at com.tangosol.util.MapEvent.dispatch(MapEvent.java:195)
     at com.tangosol.coherence.component.util.CacheEvent.run(CacheEvent.CDB:18)
     at com.tangosol.coherence.component.util.daemon.queueProcessor.Service$EventDispatcher.onNotify(Service.CDB:17)
     at com.tangosol.coherence.component.util.Daemon.run(Daemon.CDB:35)
     at java.lang.Thread.run(Thread.java:595)I get this during a cache.put() call. Any idea what this could be about?
Thanks
Ghanshyam

Answer 1

This is an issue with my code. I was selectively serializing a class member and relying on EOFException to detect if the class member should be initialized during readExternal(). Following shows the situation:
public class A implements ExternalizableLite{
     private A1 a1 = null; // A1 is ExternalizableLite
     private A2 a2 = null; // A2 is ExternalizableLite
     public A(){}
     public void setA1(A1 a1){ this.a1 = a1; }
     public void readExternal(DataInput in) throws IOException {
         this.a1.readExternal(in);
         this.a2 = new A2();
         try{
             this.a2.readExternal(in);
         catch(EOFException ex){ // a2 is null
             this.a2 = null;
    public void writeExternal(DataOutput out) throws IOException {
        this.a1.writeExternal(out);
        if(this.a2 != null) this.a2.writeExternal(out);
}A map had the above class A as the value and when the map was getting serialized, I was getting the exception. I changed class A (as below) to always initialize a2 to a non-null but empty class and the error went away:
public class A implements ExternalizableLite{
     private A1 a1 = null; // A1 is ExternalizableLite
     private A2 a2 = new A2();
     public A(){}
     public void setA1(A1 a1){ this.a1 = a1; }
     public void readExternal(DataInput in) throws IOException {
         this.a1.readExternal(in);
         this.a2.readExternal(in);
    public void writeExternal(DataOutput out) throws IOException {
        this.a1.writeExternal(out);
        this.a2.writeExternal(out);
}This means needless serialization/deserialization when a2 is null but the hit is negligible. Is there a way to get around the null values?
Thanks
Ghanshyam