When running a load of users continuously (not a large load) on a 2 node tigase cluster connected to a 2 node MUC 'cluster' through the ReceiverBareJidLB we find that the connection between the Component and server periodically gets dropped.

This results in lost messages and internal errors like this one:

2012-12-12 07:15:10 AbstractMessageReceiver$QueueListener.run() SEVERE: [in_5-ext] Exception during packet processing: from=null, to=null, DATA=Tue Dec 11 23:15:07 2012, SIZE=159, XMLNS=null, PRIORITY=NORMAL, PERMISSION=NONE, TYPE=groupchat

java.util.ConcurrentModificationException

    at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)

    at java.util.AbstractList$Itr.next(AbstractList.java:343)

    at tigase.server.ext.ComponentProtocol.getXMPPIOService(ComponentProtocol.java:914)

    at tigase.server.ext.ComponentProtocol.getXMPPIOService(ComponentProtocol.java:81)

    at tigase.server.ConnectionManager.writePacketToSocket(ConnectionManager.java:913)

    at tigase.server.ConnectionManager.processPacket(ConnectionManager.java:514)

    at tigase.server.AbstractMessageReceiver$QueueListener.run(AbstractMessageReceiver.java:1337)

Which I see on the MUC component node side. Looks like the ComponentConnection ArrayList gets modified (new connections coming up?) while iterating over the list during attempted send of messages to users from the MUC.