Re: GTK & threads

Not long ago I wrote a simple blog post on how to use threads in GTK+
applications. You can find it here:

After reading your blog (which is very good) and screwing around with my code a little bit I still can't solve the problem.

Does anyone else have anything (my original post with code included here ...) ?

I'm developing a program(s) which runs in the client/server environment. I'm using GTK, sockets, and threads. (GTK and threads only on the client side.) I don't have very much experience using threads and this is the first time I've tried to call GTK functions within a thread, and I'm having problems. I've tried different ways of approaching the problem but can't seem to get anywhere. I suspect there's something I don't understand about thread processing or I'm under some misconception. Maybe someone can help me? Any help is much appreciated.

I get the following errors when trying to run the code below (the errors show up when the program calls gtk_dialog_run() in the thread (Wait4Challenge()):

src/xcb_io.c:242: process_responses: Assertion `(((long) (dpy->last_request_read) - (long) (dpy->request)) <= 0)' failed.
Fatal IO error 0 (Success) on X server :0.0.

void *
Wait4Challenge () {
     int wsock, x, port = 0, listensock, connected;
     char buffer[5000], *msg[5], challenger[50];

     listensock = -1;
     for (x = 0; x < 5; x++)
         msg[x] = NULL;

     wsock = get_connection (SOCK_STREAM, port, &listensock);

     connected = 1;
     while (connected) {
         GtkWidget *dialog;
         int response;

         if (sock_gets (wsock, &buffer[0], sizeof (buffer)) < 0) {
             msg[0] = "There is a problem with the server.\n\n";
             outMessage (msg);
             connected = 0;

         if (buffer[0] == 'R')
             connected = 0;

         if (buffer[0] != 'C')

         strcpy (&challenger[0], &buffer[1]);

         gdk_threads_enter ();

         dialog = gtk_message_dialog_new (GTK_WINDOW (mainwin), GTK_DIALOG_DESTROY_WITH_PARENT, GTK_MESSAGE_QUESTION,
                             GTK_BUTTONS_YES_NO, "%s has challenged you to a game.  Do you wish to play?", challenger);
         gtk_window_set_title (GTK_WINDOW (dialog), "Play Challenger?");
         response = gtk_dialog_run (GTK_DIALOG (dialog));
         gtk_widget_destroy (dialog);

         gdk_threads_leave ();

         if (response == GTK_RESPONSE_YES) {
             sock_puts (wsock, "OK\n");
             connected = 0;
         else {
             sock_puts (wsock, "NO\n");
             for (x = 0; x < 5; x++)
                 msg[x] = NULL;

     shutdown (wsock, SHUT_RDWR);
     close (wsock);
     return (NULL);

main (int argc, char *argv[]) {
     g_thread_init (NULL);
     gdk_threads_init ();

     gtk_init (&argc, &argv);

     mainwin = gtk_window_new (GTK_WINDOW_TOPLEVEL);
     gtk_widget_set_usize (mainwin, WINSIZEX, WINSIZEY);
     gtk_widget_realize (mainwin);

     gtk_widget_add_events (mainwin, GDK_BUTTON_PRESS_MASK);
     gtk_signal_connect (GTK_OBJECT (mainwin), "delete_event", GTK_SIGNAL_FUNC (delete_event), 0);

     gtk_widget_show_all (mainwin);

     if (!g_thread_create (Wait4Challenge, NULL, FALSE, NULL))
         syslog (LOG_INFO, "error trying to create new thread");

     gdk_threads_enter ();

     gtk_main ();

     gdk_threads_leave ();

     return 0;

Marshall Lake -- mlake mlake net --

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