Bug 227828

Happens here, too. But looks like the bug is somewhere else -- I see odd
behavior in other apps, too. I'm still investigating.... 

Bob, can you please try to run gconf-editor for example? Does it crash for you
shortly after printing "Bonobo accessibility support initialized", too?

No, gconf-editor installed and ran properly. In this case, it did respond with:
GTK Accessibility Module initialized
Bonobo accessibility support initialized

but then immediately launched the gui and worked fine in both user and root modes.

/me is confused -- it seems to work fine if you start if from another machine
via ssh

Ah...well then, would you please start mine? ;) - still borking here.

I've tried to investigate this issue too and the problem seems to be caused
by a call to gnome_program_init. If the GDK threads subsystem is already
initialized (gdk_threads_init) and gnome_program_init is called, something
within the gnome_program_init function locks the GDK threads subsystem, but
doesn't unlock it. When mail-notification tries to acquire the lock it fails in
doing so, thus a deadlock. I'll try to investigate this issue further.

It looks like the cause of this problem is to be found in at-spi.
at-spi recently had a change (1) which should fix a deadlock problem
in Ekiga, but apparantly it also introduced a new bug. Due to this change
the function GDK_THREADS_ENTER can only be called when the g_main_loop is running.
This behaviour can be reproduced by using test program 1. Test program 2
shows that starting the g_main_loop before using GDK_THREADS_ENTER 'solves'
this problem. So, as a workaround to this problem the calls to GDK_THREAD_ENTER
and GDK_THREADS_LEAVE can be removed from the main() function, but I don't know
what further consequences this change might have. 

Anyway, about at-spi, when I start mail-notification from gdb and put
breakpoints on gdk_threads_impl_lock and gdk_threads_impl_unlock it looks
like the gdk_threads_impl_unlock breakpoint gets hit first...

#0  gdk_threads_impl_unlock () at gdk.c:384
#1  0x00fbc970 in ?? () from /usr/lib/gtk-2.0/modules/libgail.so
#2  0x0012f16b in atk_misc_threads_leave (misc=0x8801660) at atkmisc.c:112
#3  0x0054212e in spi_atk_bridge_register_application (registry=<value optimized
out>) at bridge.c:314
#4  0x00542767 in spi_atk_bridge_do_registration () at bridge.c:271
#5  0x0054416a in atk_bridge_init (argc=0x3e44448, argv=0x3e4444c) at bridge.c:231
#6  0x03becba9 in default_display_notify_cb (display_manager=0x87d6340) at
gtkmodules.c:413
#7  0x00315819 in g_cclosure_marshal_VOID__PARAM () from /lib/libgobject-2.0.so.0
#8  0x00308d9b in g_closure_invoke () from /lib/libgobject-2.0.so.0
#9  0x00319433 in ?? () from /lib/libgobject-2.0.so.0
#10 0x0031a957 in g_signal_emit_valist () from /lib/libgobject-2.0.so.0
#11 0x0031ab19 in g_signal_emit () from /lib/libgobject-2.0.so.0
#12 0x0030d171 in ?? () from /lib/libgobject-2.0.so.0
#13 0x00309b5f in ?? () from /lib/libgobject-2.0.so.0
#14 0x0030ed22 in g_object_notify () from /lib/libgobject-2.0.so.0
#15 0x005e96e8 in IA__gdk_display_manager_set_default_display
(display_manager=0x87d6340, display=0x87e3098) at gdkdisplaymanager.c:243
#16 0x005e0d36 in IA__gdk_display_open_default_libgtk_only () at gdk.c:289
#17 0x03bd5bcf in IA__gtk_init_check (argc=0xbf8eecd4, argv=0xbf8eecd0) at
gtkmain.c:889
#18 0x03bd5c04 in IA__gtk_init (argc=0xbf8eecd4, argv=0xbf8eecd0) at gtkmain.c:924
#19 0x00d0b136 in bonobo_ui_gtk_post_args_parse (program=0x87ca810,
mod_info=0xd4f440) at bonobo-ui-init-gtk.c:59
#20 0x009e7774 in gnome_program_postinit (program=0x87ca810) at gnome-program.c:1700
#21 0x009e9755 in gnome_program_init_common (type=142374072, app_id=0x808379b
"mail-notification", app_version=0x8082f76 "4.0", module_info=0x222620, 
    argc=1, argv=0xbf8ef004, first_property_name=0x8082f62 "human-readable-name", 
    args=0xbf8eede8
"�/\b\bW/\b\bR/\b\bC/\b\b>/\b\b2/\b\b'/\b\b\034/\b\b\023/\b\b\b/\b\b(�\216�",
nparams=-1, params=0x0) at gnome-program.c:1932
#22 0x009e9a81 in gnome_program_init (app_id=0x808379b "mail-notification",
app_version=0x8082f76 "4.0", module_info=0x222620, argc=1, argv=0xbf8ef004, 
    first_property_name=0x8082f62 "human-readable-name") at gnome-program.c:1748
#23 0x08058eab in main (argc=1, argv=0xbf8ef004) at mn-main.c:359

...and afterwards the gdk_threads_impl_lock breakpoint gets reached...

#0  gdk_threads_impl_lock () at gdk.c:377
#1  0x00f86940 in ?? () from /usr/lib/gtk-2.0/modules/libgail.so
#2  0x00db614b in atk_misc_threads_enter (misc=0x949c660) at atkmisc.c:79
#3  0x004b6172 in spi_atk_bridge_register_application (registry=<value optimized
out>) at bridge.c:318
#4  0x004b6767 in spi_atk_bridge_do_registration () at bridge.c:271
#5  0x004b816a in atk_bridge_init (argc=0x3e44448, argv=0x3e4444c) at bridge.c:231
#6  0x03becba9 in default_display_notify_cb (display_manager=0x9471340) at
gtkmodules.c:413
#7  0x002a3819 in g_cclosure_marshal_VOID__PARAM () from /lib/libgobject-2.0.so.0
#8  0x00296d9b in g_closure_invoke () from /lib/libgobject-2.0.so.0
#9  0x002a7433 in ?? () from /lib/libgobject-2.0.so.0
#10 0x002a8957 in g_signal_emit_valist () from /lib/libgobject-2.0.so.0
#11 0x002a8b19 in g_signal_emit () from /lib/libgobject-2.0.so.0
#12 0x0029b171 in ?? () from /lib/libgobject-2.0.so.0
#13 0x00297b5f in ?? () from /lib/libgobject-2.0.so.0
#14 0x0029cd22 in g_object_notify () from /lib/libgobject-2.0.so.0
#15 0x004d66e8 in IA__gdk_display_manager_set_default_display
(display_manager=0x9471340, display=0x947e098) at gdkdisplaymanager.c:243
#16 0x004cdd36 in IA__gdk_display_open_default_libgtk_only () at gdk.c:289
#17 0x03bd5bcf in IA__gtk_init_check (argc=0xbf8d14c4, argv=0xbf8d14c0) at
gtkmain.c:889
#18 0x03bd5c04 in IA__gtk_init (argc=0xbf8d14c4, argv=0xbf8d14c0) at gtkmain.c:924
#19 0x003e9136 in bonobo_ui_gtk_post_args_parse (program=0x9465810,
mod_info=0x42d440) at bonobo-ui-init-gtk.c:59
#20 0x00cef774 in gnome_program_postinit (program=0x9465810) at gnome-program.c:1700
#21 0x00cf1755 in gnome_program_init_common (type=155591864, app_id=0x808379b
"mail-notification", app_version=0x8082f76 "4.0", module_info=0x943620, 
    argc=1, argv=0xbf8d17f4, first_property_name=0x8082f62 "human-readable-name", 
    args=0xbf8d15d8
"�/\b\bW/\b\bR/\b\bC/\b\b>/\b\b2/\b\b'/\b\b\034/\b\b\023/\b\b\b/\b\b\030\026\215�",
nparams=-1, params=0x0) at gnome-program.c:1932
#22 0x00cf1a81 in gnome_program_init (app_id=0x808379b "mail-notification",
app_version=0x8082f76 "4.0", module_info=0x943620, argc=1, argv=0xbf8d17f4, 
    first_property_name=0x8082f62 "human-readable-name") at gnome-program.c:1748
#23 0x08058eab in main (argc=1, argv=0xbf8d17f4) at mn-main.c:359

Should we reassign this problem to at-spi ?

1. http://bugzilla.gnome.org/show_bug.cgi?id=329454 

Created attachment 148332 [details]
testcase for the deadlock which occurs when using GDK_THREADS_ENTER while the g_main_loop is not running

Created attachment 148333 [details]
testcase for the deadlock which doesn't occur when using GDK_THREADS_ENTER using the g_main_loop

(In reply to comment #5)
>  I'll try to investigate this issue further.

Many thx for your help Erik

(In reply to comment #6at-spi)
> Should we reassign this problem to at-spi ?
> 1. http://bugzilla.gnome.org/show_bug.cgi?id=329454 

Maybe adding the owner (mclasen) to the CC-list of this bug helps -- he's quite
helpful if he finds time. If he doesn't comment in the next days it might be the
best to file a separate bug to make tracking easier. 

The testcase in comment 7 has a bug: You should call 

g_thread_init (NULL)
gdk_threads_init ();
GDK_THREADS_ENTER();

first thing in your program. Calling GDK_THREADS_ENTER() after
gnome_program_init() is too late, since gnome_program_init is making
gtk calls.

actually, calling this a bug is a bit strong. This used to work just fine, but 
the a11y stack is now assuming that it is always called under the GDK lock.

In that case, shouldn't the GTK documentation be updated to clarify this behaviour?

Should upstream be informed about this issue?

The GDK threads documentation has always recommended taking the GDK lock right
after gdk_threads_init().

Reported upstream:
https://savannah.nongnu.org/bugs/index.php?19189

FYI, disabling accessibility features with gnome-at-properties works around the
problem

Confirmed that disabling accessibility with gnome-at-properties is a work-around.

Based on the comments from Matthias I've created a small patch which fixes the
problem. I've been running mail-notification with it for a few days and haven't
found any difficulties with it. 

Created attachment 149595 [details]
Patch to fix the deadlock

Still waiting for 231767 to get fixed, as mail-notification otherwise fails to build

Bug #231767 is fixed now.  Update to evolution-2.10.0-7.fc7.

(In reply to comment #20)
> Bug #231767 is fixed now. 

Saw it, but there is another problem now :-( See Bug 235056

(In reply to Bug 235056 Comment #3)
> Should be fixed in evolution-2.10.0-9.fc7.

Many thanks for your help Matthew.
 
> Hopefully that's the last of the build issues.

Seems so -- it build fine now and the problem is gone. Erik, thanks for your patch.

Updated package should be pushed out soon.