Re: gtk + threads

["Brian J. Tarricone" <bjt23 cornell edu>]

Muthu wrote:

> Hi!
> Im assuming you are talking about X Errors.
> Which cropup on the terminal, and say
> X out of sync, etc.
>
> A little bit of reading the gtk-app-devel list
> will show you how, 
> X window system calls must be made from only
> one thread. Making X calls from two threads
> will cause a crash.
>  
actually, that's not true.  assuming your X11 client libraries are 
thread-safe, you've called XInitThreads(), and are either a) using two 
separate Display* pointers obtained via two different invocations of 
XOpenDisplay(), or b) locking a single Display* with XLockDisplay() 
while using it in all threads, you should be fine.

> I think you must set the gtk_* calls from the
> idle_function alone. Thatis , it must be a
> part of the main loop that works the GUI.
>  
or, you have to start off your app with:

g_thread_init(NULL);
gdk_threads_init();
g_init(&argc, &argv);

wrap gtk_main() between gdk_threads_enter() and gdk_threads_leave(), 
and, anytime you access gdk/gtk from a:
1) idle function
2) timeout function
3) function running in a thread other than the main one
you surround such calls with gdk_threads_enter()/gdk_threads_leave().

now, this is sometimes a bit of work, so often it's easier -- as the 
original poster hinted at -- just to not init the threads system at all, 
and, when you need to call gtk/gdk from another thread, either stick it 
in an idle function that gets scheduled via g_idle_add(), or use a 
GAsyncQueue to communicate between the GUI thread and the worker threads.

   -brian