Re: GTypeModule and threads

On Mon, 15 Jun 2009 19:17:54 +0200
Jannis Pohlmann <jannis xfce org> wrote:

> Hey,
> is GTypeModule supposed to be thread-safe? I'm currently working on an
> application with a plugin interface based on GTypeModule. The
> application itself runs several threads which create objects of the
> types exported by the GTypeModule. 
> Now, if I wait long enough and give the application enough to work on,
> I always end up with the same result: the application crashes with the
> following error:
> GLib-GObject:ERROR:gtype.c:1135:type_data_ref_Wm: assertion failed:
> (node->data->common.ref_count > 0)
> I suppose this is a race condition where one thread unref's the last
> instance of a type exported by the GTypeModule and another tries to
> create a new instance at about the same time. Please correct me if I'm
> wrong here.

I played with this a bit more and it seems it's not related to
GTypeModule all. Even if I make the GModule resident and never unuse
the GTypeModule, I still end up with this error. So the question is, is
GType or at least g_object_new() thread-safe? Or if it's not, shouldn't
it be?

Excerpt of the backtrace of the above error:

#3  0xb7ec0f17 in g_assertion_message () 
#4  0xb7ec14dd in g_assertion_message_expr ()
#5  0xb7f6458f in g_type_class_ref ()
#6  0xb7f49268 in g_object_newv ()
#7  0xb7f497b1 in g_object_new_valist ()
#8  0xb7f49920 in g_object_new ()

Any help would be greatly appreciated. Seems like I can reduce the risk
of this error to appear by protecting parts of my code with mutexes but
that still isn't 100% safe and it looks to me like this might be a bug
in GObject/GType.


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