Re: threads gdk/Xlib

[Olexiy Avramchenko <olexiy ctech cn ua>]

StÃphane Konstantaropoulos wrote:
> Hello all,
>
> I am programming a testing app for a gtk widget that embeds Xine and I
> am facing little problems with threads and XLib: the application crashes
> all the time whith "Xlib: unexpected async reply"
>
> It got fixed only when I called the following functions in the following
> sequence:
>
> XInitThreads ();
> g_thread_init(NULL);    
> gdk_threads_init();
> gtk_init(&argc, &argv);
>
> There is no need to put gtk_main() between gdk_threads_enter() and gdk_threads_leave().
You need to put gtk_main() between gdk_threads_enter/leave() if you start any 
thread before. If you start thread from main loop somehow, these calls aren't 
necessary.

> To sum up: there are calls to Xlib from other threads, created by Xine. Gdk also calls Xlib but only from the
> main thread (my app does not create any). Xine always calls XLockDisplay() before doing any of these calls.
If you dont use threads in your application you can drop g_thread_init(), 
gdk_threads_init() calls on the floor. The magic in your case is in 
XInitThreads() somehow.

> Question then:
>
> - Does Gdk call XLockdisplay() at all?
No. gdk_threads_init/enter/leave() stuff acts like 
XInitThreads(),XLockDisplay(),XUnlockDisplay().

> - Do you need to call XInitThreads() before gdk_threads_init() ? -> that's the way it seems to work for me.
No.

> - Why is this (ie the interaction between Xlib threads and Gdk threads) not documented anywhere?
What system are you using ? What kind of application do you have ? What version 
of GTK+ ? Maybe you're linking to some library that wants X threads be initialized ?

        Olexiy