Re: Gtkmm and fork()

[Chris Vine <chris cvine freeserve co uk>]

On Sun, 11 Apr 2010 17:42:38 +0100
Chris Vine <chris cvine freeserve co uk> wrote:
> You should call _exit() (and incidentally NOT exit()) at the end of
> the child process.  (That is at the end of the if block representing
> the child process.)

And incidentally if you do that, you will probably get away with
omitting the call to Gtk::Main::quit().  I have been looking through
some of my code to see why I do what I do and the principle reason why
I fork() and then exec() from a thread is to call waitpid() in the
parent thread in order to obtain an exit status, which that thread then
sends on to the program main loop with an event object (which under the
hood comprises an idle source callback).

If you don't fork from a new thread, what you must avoid is the child
process ever entering its copy of the main loop or in any other way
attempting to invoke any X functions. In the example given to you if you
call _exit() at the end of the relevant if block it won't do so, even
without the call to Gtk::Main::quit(). Likewise, if all you were going
to do is call exec() shortly after the fork() and are not interested in
exit status.

Chris