Programming Erlang, 2nd Edition

When Things Go Wrong

This section lists some common problems (and their solutions).

Stopping Erlang

Erlang can sometimes be difficult to stop. Here are a number of possible reasons:

• The shell is not responding.

• The Ctrl+C handler has been disabled.

• Erlang has been started with the -detached flag, so you may not be aware that it is running.

• Erlang has been started with the -heart Cmd option. This option causes an OS monitor process to be set up that watches over the Erlang OS process. If the Erlang OS process dies, then Cmd is evaluated. Often Cmd will simply restart the Erlang system. This is one of the tricks we use when making fault-tolerant nodes—if Erlang itself dies (which should never happen), it just gets restarted. The trick here is ...