Re: gtk + threads

[John K Luebs <jkluebs luebsphoto com>]

On Mon, Jan 31, 2005 at 10:44:53AM +0100, Felix Kater wrote:
> Hi Muthu,
>
> > X window system calls must be made from only
> > one thread. Making X calls from two threads
> > will cause a crash.
This is wrong. Xlib is itself thread agnostic. Xlib has no
thread local state. According to X docs (XInitThreads), as long as all
calls to Xlib are serialized, you can call X from any thread, it doesn't
care. The XInitThreads and XLock are simply one option to provide
locking if you have no other. If you provide your own lock, then you
don't even need to call XInitThreads.
> > 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.
This is a recommended pattern, but not a technical requirement.
> May I ask you again what's the essetial point about the
> single-thread-strategy handling gtk:
>
> (a) Is it the fact that there will never be more than one access to gtk
> at the same time -- or
>
> (b) something else I did not get (e.g. must be *one* thread etc)?
>
> In case of (a): Shouldn't it be enough then to lock all access to gtk by
> the same mutex/lock which could then be spread over different functions
> and threads then?
Exactly. There is a single lock for GDK and GTK. It's documented in the
GDK manual on the chapter about threading.

 --jkl