Re: strange deadlock ...

[Owen Taylor <otaylor redhat com>]

Michael Meeks <michael ximian com> writes:

> I have a deadlock like this:
> 
> 	Of course, it's entirely likely to be my own silly fault - but I
> simply connect a button click to something doing a CORBA operation:

The basic idea here is that you need to release the GTK+ lock before calling
g_main_loop_run() or g_main_context_iteration().

Of course, you are sort of in a pickle here because giop_recv_buffer_get()
has no idea whether it has the GTK+ lock or not, and you presumably
don't want to require everybody to release the GTK+ lock before making
all CORBA calls.

But on the other hand, if you are doing a recursive main loop -- and you
are -- then you _do_ have to release the GTK+ lock.

I don't really have a good solution - as soon as you call g_thread_init(),
then suddenly your required to think about situations that come up when
you are using GTK+ from multiple threads. I'll think about it some more
and see if I come up with a suggestion.

Regards,
                                                Owen

 
> #4  0x4034f0de in gdk_event_prepare (source=0x8063660,
> timeout=0xbfffe0b8) at gdkevents-x11.c:1702
> #5  0x407570a5 in g_main_context_prepare (context=0x8051938,
> priority=0xbfffe0f8) at gmain.c:1904
> #6  0x4075792f in g_main_context_iterate (context=0x8051938, block=1,
> dispatch=1, self=0x8050040) at gmain.c:2190
> #7  0x40757bc7 in g_main_context_iteration (context=0x0, may_block=1) at
> gmain.c:2269
> #8  0x405ce1c2 in giop_recv_buffer_get (ent=0xbfffe1e0,
> block_for_reply=1) at giop-recv-buffer.c:812
> ...
> #42 0x401e403d in gtk_main_do_event (event=0x80f7530) at gtkmain.c:926
> #43 0x4034f247 in gdk_event_dispatch (source=0x8063660, callback=0,
> user_data=0x0) at gdkevents-x11.c:1745
> #44 0x40756d88 in g_main_dispatch (context=0x8051938) at gmain.c:1593
> #45 0x407576b5 in g_main_context_dispatch (context=0x8051938) at
> gmain.c:2129
> #46 0x40757a50 in g_main_context_iterate (context=0x8051938, block=1,
> dispatch=1, self=0x8050040) at gmain.c:2210
> #47 0x4075810e in g_main_loop_run (loop=0x80f8520) at gmain.c:2430
> #48 0x4057a8ae in bonobo_main () at bonobo-main.c:276
> 
> 	The problem being of course that gdk_event_dispatch is holding the
> GDK_THREADS_ENTER mutex, that gdk_event_prepare tries to take.