Concurrent Modification Exception

[Sreelu]

While iam trying to join players to room, and update room variables, send some extension response..facing concurrent modification exception.
This is not happening everytime..Only at times,
Please help in resolving this issue
PFB exception stack trace:

21 Jun 2017 | 17:20:21,275 | WARN | Timer-8 | v2.protocol.SFSIoHandler | | com.smartfoxserver.v2.exceptions.SFSRuntimeException:
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Exception: com.smartfoxserver.v2.exceptions.SFSRuntimeException
Message: java.util.ConcurrentModificationException
+--- --- ---+
Stack Trace:
+--- --- ---+
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.pojo2sfs(DefaultSFSDataSerializer.java:1399)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.encodeObject(DefaultSFSDataSerializer.java:834)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.obj2bin(DefaultSFSDataSerializer.java:508)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.object2binary(DefaultSFSDataSerializer.java:491)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.encodeObject(DefaultSFSDataSerializer.java:830)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.obj2bin(DefaultSFSDataSerializer.java:508)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.object2binary(DefaultSFSDataSerializer.java:491)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.encodeObject(DefaultSFSDataSerializer.java:830)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.obj2bin(DefaultSFSDataSerializer.java:508)
com.smartfoxserver.v2.protocol.serialization.DefaultSFSDataSerializer.object2binary(DefaultSFSDataSerializer.java:491)
com.smartfoxserver.v2.entities.data.SFSObject.toBinary(SFSObject.java:234)
com.smartfoxserver.v2.protocol.binary.BinaryIoHandler.handleWrite(BinaryIoHandler.java:80)
com.smartfoxserver.v2.protocol.SFSIoHandler.onDataWrite(SFSIoHandler.java:222)
com.smartfoxserver.v2.protocol.SFSProtocolCodec.onPacketWrite(SFSProtocolCodec.java:157)
com.smartfoxserver.bitswarm.core.BitSwarmEngine.writeToSocket(BitSwarmEngine.java:397)
com.smartfoxserver.bitswarm.core.BitSwarmEngine.write(BitSwarmEngine.java:391)
com.smartfoxserver.bitswarm.io.Response.write(Response.java:70)
com.smartfoxserver.v2.api.response.SFSResponseApi.sendExtResponse(SFSResponseApi.java:91)
com.smartfoxserver.v2.api.SFSApi.sendExtensionResponse(SFSApi.java:1497)
com.smartfoxserver.v2.extensions.BaseSFSExtension.send(BaseSFSExtension.java:439)
com.smartfoxserver.v2.extensions.BaseSFSExtension.send(BaseSFSExtension.java:416)
com.common.ServerResponseManager.sendMessage(ServerResponseManager.java:1766)
com.common.ServerResponseManager.sendSeatAllocationSuccess(ServerResponseManager.java:813)
com.strike.MyAdapter.sendSeatAllocationSucces(MyAdapter.java:230)
com.game.BaseGameSTM.notifySeatAlotted(BaseGameSTM.java:458)
com.game.BaseGameSTM.notifySeat(BaseGameSTM.java:390)
com.game.BaseGameSTM.seating(BaseGameSTM.java:259)
com.game.BaseGameSTM.access$0(BaseGameSTM.java:256)
com.game.BaseGameSTM$4.run(BaseGameSTM.java:248)
java.util.TimerThread.mainLoop(Unknown Source)
java.util.TimerThread.run(Unknown Source)

[Lapo]

It looks like you're recycling an SFSObject causing concurrency issues.
Keep in mind that SFSObject/Array is not thread safe so once you have used it you should not reuse the same object for something else.

Example:
you create an SFSObject,
populate it
send it to a bunch of users
then modify it again for some other reason <-- problem!

Check you code for a similar situation. The stack trace should point you in the right direction.

cheers

[Sreelu]

Thanku..'ll look into