Re: GTK Thread init problem

[James Scott Jr <skoona verizon net>]

On Mon, 2007-04-16 at 18:09 +0530, prabahar k wrote:

> hi
>  i am trying to use a threaded GTK program. While running the
> program it gives segmentation fault and it seem to be an
> thread init problem. is there any thing i am missing? Please
> give u r comments.
>
> the code is:
> /***********************gtk19.c**************************/
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
> #include <time.h>
> #include <gtk/gtk.h>
> #include <glib.h>
> #include <pthread.h>
>
> pthread_t thrd1;
>
> void destroy (GtkWidget *widget, gpointer data)
> {
>  gtk_main_quit ();
> }
>
> void *argument_thread (void *args)
> {
> gdk_threads_enter ();
>  for (;;)
>    {
>      /* sleep a while */
>
>
>
>          sleep(1);
>          g_print("Inside thread");
>
>
>    }
> gdk_threads_leave ();
>  return NULL;
> }
>
> int main (int argc, char *argv[])
> {
>  GtkWidget *window;
>
>   /* init threads */
>
>  g_thread_init (NULL);
>  gdk_threads_init ();
>  /* init gtk */
>  gdk_threads_enter ();
> /*[Line :70] */                gtk_init(&argc, &argv);
>
>  g_print("After init\n");
>
>  /* create a window */
>  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
>
>  gtk_signal_connect (GTK_OBJECT (window), "destroy",
>                      GTK_SIGNAL_FUNC (destroy), NULL);
>
>  gtk_container_set_border_width (GTK_CONTAINER (window), 10);
>  gtk_widget_show (window);
>
>  pthread_create (&thrd1, NULL, argument_thread, NULL);
>
>  gtk_main ();
>  gdk_threads_leave ();
>
>  return 0;
> }
> /**************************************************/
>
> I compile it as
> gcc -Wall -g gtk19.c -o base -lpthread `pkg-config --cflags gtk+-2.0`
> `pkg-config --libs gtk+-2.0` `gtk-config --cflags --libs gthread`
>
>
> After core dump bt gives
> #0  0x00484aa2 in pthread_mutex_lock () from /lib/libpthread.so.0
> #1  0x0025f63a in g_mem_chunk_new () from /usr/lib/libglib-2.0.so.0
> #2  0x002408c6 in g_ptr_array_sized_new () from /usr/lib/libglib-2.0.so.0
> #3  0x002408e3 in g_ptr_array_new () from /usr/lib/libglib-2.0.so.0
> #4  0x00146f0d in gdk_x11_atom_to_xatom () from /usr/lib/libgdk-x11-2.0.so.0
> #5  0x00146f7b in gdk_atom_intern () from /usr/lib/libgdk-x11-2.0.so.0
> #6  0x001454d9 in gdk_keymap_translate_keyboard_state () from
> /usr/lib/libgdk-x11-2.0.so.0
> #7  0x0011267e in gdk_pre_parse_libgtk_only () from /usr/lib/libgdk-
> x11-2.0.so.0
> #8  0x00598330 in gtk_disable_setlocale () from /usr/lib/libgtk-x11-2.0.so.0
> #9  0x00264c8c in g_option_context_parse () from /usr/lib/libglib-2.0.so.0
> #10 0x00598789 in gtk_parse_args () from /usr/lib/libgtk-x11-2.0.so.0
> #11 0x005987c3 in gtk_init_check () from /usr/lib/libgtk-x11-2.0.so.0
> #12 0x00598801 in gtk_init () from /usr/lib/libgtk-x11-2.0.so.0
> #13 0x08048be7 in main (argc=2, argv=0xbfab7144) at gtk19.c:70
>
>
>
>
> ---
>
> prabahar
> _______________________________________________
> gtk-app-devel-list mailing list
> gtk-app-devel-list gnome org
> http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list



prabahar,

I just modified your code to show the needed changes.  Notice that the
gdk_threads_enter/leave is removed from the thread and the thread is
created using glib's api.  I also updated the includes and compile
command.

James,

BEGIN CODE ***************************
/***********************gtk19m.c**************************/
/* gcc -O2 -Wall `pkg-config --cflags --libs gtk+-2.0 glib-2.0
gthread-2.0` gtk19m.c -o gtk19m */

#include <gtk/gtk.h>
#include <glib.h>


void destroy (GtkWidget *widget, gpointer data)
{
 gtk_main_quit ();     /* the window is almost invalid when this is
called */
                       /* consider "delete-event" */
}

/*
 * Does not need gdk_threads_enter/leave() wrapping 
 *      if no GTK/GDK apis are called
*/
gpointer argument_thread (gpointer *args)
{
 for (;(gboolean)*args;)   /* exit loop when flag is cleared */
   {
     /* sleep a while */

         g_usleep(1000000);
         g_print("Inside thread");
   }

 g_thread_exit (NULL);    /* not required just good pratice */
 return NULL;
}

int main (int argc, char *argv[])
{
 GtkWidget *window;
 GThread   *gth = NULL;         /* thread id */
 gboolean  b_run_flag = TRUE;   /* used as exit flag for threads */


 g_thread_init (NULL);    /* Initialize GLIB thread support */
 gdk_threads_init ();     /* Initialize GDK locks */


 gdk_threads_enter ();    /* Acquire GDK locks */
 gtk_init(&argc, &argv);  /* initialize GTK    */

 g_print("After init\n");

 /* create a window */
 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

 gtk_signal_connect (GTK_OBJECT (window), "destroy",
                     GTK_SIGNAL_FUNC (destroy), NULL);

 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
 gtk_widget_show (window);

 /* Create a bg thread using glib */
 gth = g_thread_create ( (GThreadFunc)argument_thread,
(gpointer)&b_run_flag, TRUE, NULL);

 gtk_main (); /* --- ANYTHING EXECUTED VIA THIS LOOP HAS GDK LOCKS
ALREADY APPLIED */
 gdk_threads_leave ();  /* release GDK locks */

 b_run_flag = FALSE;  /* flag threads to stop and exit */
 g_thread_join(gth);  /* wait for thread to exit */

 return 0;
}

END CODE *****************************