A few other services are also provided. For instance, users will be warned if a process sends a message to itself. Having a process send to itself is legal, but it displays poor performance and requires enough buffer space that it can occasionally cause hangs for large messages. Many times, the debug level 0 code will simply hang, leaving the developer without any clue as to what has gone wrong. This may be caused, for instance, by trying to receive from a process that is not in the current context.
Warning message is printed, and execution proceeds.