Re: [gtk-list] gdk_thread_leave() in call back func, otherwise dead lock.

[Owen Taylor <otaylor redhat com>]

Yasushi Shoji <yashi@yashi.com> writes:

> Hi all,
> 
> the following code will likely deadlocked, if I don't call
> gdk_thread_leave() before pthread_join(), because: 
> 
> from gtkfaq-5.html#ss5.2
> > Callbacks from GTK+ (signals) are made within the GTK+ lock.
> 
> deadlock happnes:
> 
> - loop_thread is waiting on sleep()
> - button is clicked and GDK_THREADS_ENTER() is called in
>   gdk_event_dispatch() for callback function.
> - callback function calls pthread_join() and block itself to wait
>   loop_thread.
> - loop_thread leaves sleep() and trys to GDK_THREADS_ENTER() but it's
>   already locked by callback function and block itself
> - DEADLOCK!
> 
> 
> My question is:
> 
> - Is it ok to call gdk_thread_leave() in call-back function, if the
>   function does not call any gtk functions?

Yes, in this is fine. GTK+ is designed to be reentrant from within
callbacks. 

If you try hard enough, especially if you connect to some of the more
"internal" signals of GTK+ like ::map, ::container_add, then you
might be able to break GTK+, but in general, it should be fine to
release (and then reacquire) the GDK lock in any callback you would
normally connect to.

Regards,
                                        Owen