AS 5.1.0.GA user (see forum thread) reports repeated logging of java.io.InterruptedIOException from MPING, coming from the task thread that's running Discovery$PingSenderTask. The thread is interrupted during the send of the discovery packet. From the pattern of logging (repeated, and after initial cluster formation) my assumption is the task is triggered by MERGE2. My assumption is also that the thread is interrupted because Discovery.findInitialMembers() has timed out waiting for a response, and has called PingSenderTask.stop(), which ultimately interrupts the task thread. The MPING discovery timeout is 2 secs; the unusual thing here is the discovery packet hasn't been sent w/ in 2 seconds.
There are really two aspects to this JIRA:
1) See if there is any problem with the way JGroups is scheduling the task, or configuring the multicast socket etc. It looks OK to me, and quite possibly this is due to an environmental issue on the user's system. Would be good to understand though, as this is the second report I've had of this general problem.
2) Change MPING.sendMcastDiscoveryRequest to handle InterruptedIOException or let it propagate. I see PingSenderTask.run() is coded to handle InterruptedIOException by logging a WARN, but MPING.sendMcastDiscoveryRequest doesn't let it propagate and instead logs it as an ERROR with a stack trace.