com.hazelcast.nio.serialization.HazelcastSerializationException: java.util.ConcurrentModificationException

[al...@betgenius.com]

Greetings,

We’re getting errors in our logs like this:

com.hazelcast.nio.serialization.HazelcastSerializationException: java.util.ConcurrentModificationException
        at com.hazelcast.nio.serialization.SerializationServiceImpl.handleException(SerializationServiceImpl.java:295) ~[hazelcast-all-3.1.1.jar:3.1.1]
        at com.hazelcast.nio.serialization.SerializationServiceImpl.toData(SerializationServiceImpl.java:194) ~[hazelcast-all-3.1.1.jar:3.1.1]
        at com.hazelcast.nio.serialization.SerializationServiceImpl.toData(SerializationServiceImpl.java:157) ~[hazelcast-all-3.1.1.jar:3.1.1]
        at com.hazelcast.map.MapService.toData(MapService.java:659) ~[hazelcast-all-3.1.1.jar:3.1.1]
        at com.hazelcast.map.proxy.MapProxyImpl.put(MapProxyImpl.java:72) ~[hazelcast-all-3.1.1.jar:3.1.1]
        at com.hazelcast.map.proxy.MapProxyImpl.put(MapProxyImpl.java:60) ~[hazelcast-all-3.1.1.jar:3.1.1]
        at <the line of our code that puts an entry into an IMap object>
        at java.lang.Thread.run(Thread.java:724) ~[na:1.7.0_25]
Caused by: java.util.ConcurrentModificationException: null
        at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894) ~[na:1.7.0_25]
        at java.util.HashMap$KeyIterator.next(HashMap.java:928) ~[na:1.7.0_25]
        at java.util.HashSet.writeObject(HashSet.java:283) ~[na:1.7.0_25]
        at sun.reflect.GeneratedMethodAccessor381.invoke(Unknown Source) ~[na:na]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_25]
        at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_25]
        at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:986) ~[na:1.7.0_25]
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1493) ~[na:1.7.0_25]
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1429) ~[na:1.7.0_25]
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1175) ~[na:1.7.0_25]
        at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1541) ~[na:1.7.0_25]
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1506) ~[na:1.7.0_25]
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1429) ~[na:1.7.0_25]
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1175) ~[na:1.7.0_25]
        at java.io.ObjectOutputStream.writeUnshared(ObjectOutputStream.java:414) ~[na:1.7.0_25]
        at com.hazelcast.nio.serialization.DefaultSerializers$ObjectSerializer.write(DefaultSerializers.java:206) ~[hazelcast-all-3.1.1.jar:3.1.1]
        at com.hazelcast.nio.serialization.StreamSerializerAdapter.write(StreamSerializerAdapter.java:48) ~[hazelcast-all-3.1.1.jar:3.1.1]
        at com.hazelcast.nio.serialization.SerializationServiceImpl.toData(SerializationServiceImpl.java:176) ~[hazelcast-all-3.1.1.jar:3.1.1]
        ... 26 common frames omitted

Does anyone have any idea what could be causing this exception?

Thanks,

Alex

[ali gurbuz]

Could you please post your key/value classes

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[ali gurbuz]

Here the problem is while hazelcast serializing HashSet you have provided, some other thread modifies it.

So you get a ConcurrentModificationException

[al...@betgenius.com]

On Friday, January 10, 2014 8:20:22 AM UTC, Gurbuz wrote:

Here the problem is while hazelcast serializing HashSet you have provided, some other thread modifies it.

So you get a ConcurrentModificationException

Thanks; that’s now what we’re thinking too.

It turns out that the value we’re putting into the IMap is sometimes a type that wraps another type that extends HashSet (without adding any thread-safety guarantees).

Thanks again,

Alex