ThreadPool rejection policy detecting stuck threads

Sometimes I find out my OOB threadpool size (which defaults to 200) in our tests too low, causing deadlock (this seems to be the case with the 64 node cluster - we've run out of OOB threads because all of them were stuck).
New rejection policy could usually silently discard the message, but in case that the thread pool does not finish anything (getCompletedTaskCount stays constant) for a period, it would throw a special exception denoting that there's possibly a deadlock (and that raising OOB threadpool could help).