[heroic]

A very fine way is to have multiple processes and connect to any at random. Now, use a message queue, say like redis, or rabbit mq to read messages and delete from queue. Since a client is only connected to only one of the servers, it eliminates the chances of sending the same message more than once to the same client. This helps in splitting the incoming messages and the outgoing(which is usually far bigger, since one message is delivered to all others in a chat room).