Bug 4909 - g_object_remove_toggle_ref CRITICAL is printed (glib sharp master)
Summary: g_object_remove_toggle_ref CRITICAL is printed (glib sharp master)
Status: RESOLVED FIXED
Alias: None
Product: Gtk#
Classification: Mono
Component: gtk-sharp ()
Version: unspecified
Hardware: PC Linux
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2012-05-06 19:10 UTC by Andres G. Aragoneses
Modified: 2012-05-25 08:56 UTC (History)
2 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Status:
RESOLVED FIXED

Description Andres G. Aragoneses 2012-05-06 19:10:08 UTC
When running Banshee with Gtk#3 I get this printed:

GLib-GObject-CRITICAL **: g_object_remove_toggle_ref: assertion `G_IS_OBJECT (object)' failed

I've tracked this down to the following reason: the finalizer on the object is being called twice, so not sure if the root cause of this is a Mono bug.

However, I have a patch ready for gtk-sharp to prevent this. I'll make a pull request now.
Comment 1 Andres G. Aragoneses 2012-05-06 19:32:01 UTC
https://github.com/mono/gtk-sharp/pull/39
Comment 2 Andres G. Aragoneses 2012-05-07 16:54:51 UTC
When I said "the finalizer on the object is being called twice, so not sure if the root cause of this is a Mono bug", I think I was actually wrong.

After digging a bit, I think I know what is happening. This is the Dispose() method in GLib.Object:

                protected virtual void Dispose (bool disposing)
                {
                        ToggleRef tref;
                        lock (Objects) {
                                if (Objects.TryGetValue (Handle, out tref)) {
                                        tref.QueueUnref (this);
                                        Objects.Remove (Handle);
                                }
                        }

                        handle = IntPtr.Zero;
                        if (tref == null)
                                return;

                        if (disposing)
                                tref.Dispose ();
                        else
                                tref.QueueUnref (this);
                }


Somehow in my 32bits system, "if (tref == null)" is false, and in my 64bits it is true (and this may not be a bug, it may just be related to performance of the CPU, because my 32bits system is much older/slower).

So, since (tref == null) can definitely happen, I think the pull request https://github.com/mono/gtk-sharp/pull/39 is still valid.

PS: The reason I'm guessing it is performance-related is because the a TimeoutHandler is used in ToggleRef.QueueUnref():

if (!idle_queued){
        Timeout.Add (50, new TimeoutHandler (PerformQueuedUnrefs));
        idle_queued = true;
}
Comment 3 Andres G. Aragoneses 2012-05-25 08:56:54 UTC
This was finally a redundant call to QueueUnref, fixed here: https://github.com/mono/gtk-sharp/commit/85b84f99f651f2a640dad0ca62ce986b9bb57aa2