I was looking into AS7-4274 and it appears that the hang happens if a client closes the connection when the server is still sending message(s) on a channel for that connection. I've isolated the issue in a testcase in remoting testsuite here https://github.com/jaikiran/jboss-remoting/commits/remoting-hang.

(Note that the test passes sometimes which indicates that this might be a race condition somewhere).