Re: GLib-CRITICAL Source ID 35 was not found when attempting to remove it

On Wed, 16 Sep 2015 10:54:15 +0530
Lokesh Chakka <lvenkatakumarchakka gmail com> wrote:

i kept gtk_thread_enter / leave for experimental purpose.
Actually issue was happening irrespective of existence of
gtk_thread_enter / leave.

You are missing the point.  You must use gdk_threads_enter() and
gdk_threads_leave() both (i) where you already have them in main(), and
(ii) also around gtk_widget_queue_draw() in the callback.

However, gdk_threads_init(), gdk_threads_enter() and gdk_threads_leave()
are deprecated in GTK+3, and only work with X11 (not on windows).
Instead, you should do what has been suggested and send an event from
the worker thread to the GTK+ main loop using g_idle_add().  Then you
do not need to bother with gdk_threads_init(), gdk_threads_enter() or
gdk_threads_leave() in your program at all.  You will however need to
call g_thread_init() at the beginning of main() with glib < 2.32.
glib >= 2.32 is thread safe without g_thread_init() (which is a no-op).


Thanks & Regards
Lokesh Chakka,
Mobile: 9731023458

On Wed, Sep 16, 2015 at 10:21 AM, markku vire <markku vire gmail com>


Nowadays gdk_threads_enter ()/leave () are deprecated, so you
should not use them in newly written code. You need to do gtk calls
from main thread instead. You can send notifications to main thread
easily using g_idle_add, which schedules them to happen on next
main loop iteration.

When working with older versions of gtk, you need to acquire gdk
lock before doing any gtk call from background thread. So, you
should move threads_enter/leave around queue_draw in your

Hope this helps,

16.9.2015 7.03 "Lokesh Chakka" <lvenkatakumarchakka gmail com>


I have written small piece of code and I am seeing thread_function
is getting stuck. If I try to close the window, I am seeing GLib
Critical error

Can some body please help me fixing the issue ?

following is the code:

#include <pthread.h>

GtkDrawingArea *darea;
GtkVBox  *main_window_box;
GtkWindow    *main_window;

const int size = 500;
int i;

static void my_draw_event( GtkWidget *widget, cairo_t *cr, void
*parameter )
    int a, b;
    cairo_set_source_rgb( cr, 1, 0, 0 );
    a = random()%size;
    b = random()%size;
    cairo_move_to( cr, a, a );
    cairo_line_to( cr, b, b );
    fprintf( stderr, "Values i: %4d a: %3d b: %3d\n", i, a, b );

static void *thread_function( void *parameter )
    const int seconds = 1000;

    for( i=0; i<seconds; i++ )
        gtk_widget_queue_draw( (GtkWidget*)darea );

int main()
    pthread_t th;

    gtk_init( NULL, NULL );

    main_window = (GtkWindow*)gtk_window_new(GTK_WINDOW_TOPLEVEL);


    main_window_box =
(GtkVBox*)gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
gtk_container_add (GTK_CONTAINER

    darea = (GtkDrawingArea*)gtk_drawing_area_new();
    gtk_box_pack_start( GTK_BOX( main_window_box ),
(GtkWidget*)darea, TRUE, TRUE, 0 );
    g_signal_connect( G_OBJECT(darea), "draw",
G_CALLBACK( my_draw_event ), NULL );

gtk_window_set_default_size(GTK_WINDOW(main_window), size, size );

    pthread_create( &th, NULL, thread_function, NULL );

    return 0;

Thanks & Regards
Lokesh Chakka,
Mobile: 9731023458

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