process-keeps-lisp-alive-p

Lisp cannot exit if a process is running where this slot is true (since that process keeps Lisp alive). That is normally what you want. However, if a process is purely ancillary, it is reasonable to set this slot to nil, so Lisp can automatically kill the process and exit when it is the only live process. setf can be used to change the value returned by this generic function.

An example is the background process set up in Emacs to debug non-listener processes that signal an error (see Debugging background processes in debugging.htm). These processes are started with this slot nil, since it is presumed you do not want to continue with that process when all others have been killed.

When you call exit and processes (other than the listener where the call to exit was entered) are still running, if any keep Lisp alive, you are explicitly asked if you want to kill them and exit. But if processes which do not keep Lisp alive are running, they are silently killed and Lisp exits.

See multiprocessing.htm for general information on multiprocessing.

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Created 2010.1.21.