Re: Problem running the GTK main loop in a separate thread (different from the main one).

Cristi Cobzarenco <cristi.cobzarenco@xxxxxxxxx> · Sun, 30 Aug 2009 00:49:34 +0300

Those are the options that I am using, but it doesn't work for me. I really appreciate the answer, I forgot to say, however, that I'm using MinGW under MS Windows. I now remember seeing somewhere that GTK multithreading only works on the X11 backend, so that might be the problem. I will try it on my Fedora box as soon as I get the chance.

Thanks a lot anyway.

On Sat, Aug 29, 2009 at 4:22 PM, Jorge Opaso Pazos <jorge.opaso@xxxxxxxxx> wrote:

OK. This works too:
#include <gtk/gtk.h>

static gpointer _gtkthread(gpointer a_data)
{
	gdk_threads_enter();
	gtk_main();
	gdk_threads_leave();

	return NULL;
}

static void _create_widgets()
{

	GtkWidget *l_win;
	GtkWidget *l_but;

	gdk_threads_enter();
	l_win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
	l_but = gtk_button_new_with_label("My Button");
	gtk_container_add(GTK_CONTAINER(l_win),l_but);
	gtk_widget_show_all(l_win);
	gdk_threads_leave();
}

int main(int a_argc,char **a_argv)
{
	GThread *l_th;

	g_thread_init(NULL);
	gdk_threads_init();
	gtk_init(&a_argc,&a_argv);
	l_th = g_thread_create(_gtkthread,NULL,TRUE,NULL);
	_create_widgets();
	g_thread_join(l_th);

	return 0;
}

Compile with: cc `pkg-config --cflags --libs gtk+-2.0 gthread-2.0` -o main main.c

There is no reason to wait for the main loop to start if the calls are within the gdk_threads_enter and gdk_threads_leave pair. Hope this help.

Atentamente,

Jorge Opaso Pazos
AUTOLogic LTDA

El 29-08-2009, a las 8:51, Cristi Cobzarenco escribió:

Hi,
Yeah, this works for me to, this is equivalent to my "create_in_gt" flag being on. Problem is if you try creating the widgets in the main thread.
Does this work for you?

#include <gtk/gtk.h>

static gpointer _gtkthread(gpointer a_data)
{
       gdk_threads_enter();
       gtk_main();
       gdk_threads_leave();

       return NULL;
}

int main(int a_argc,char **a_argv)
{
       GThread *l_th;
       GtkWidget *l_win;
        GtkWidget *l_but;

       g_thread_init(NULL);
       gdk_threads_init();
       gtk_init(&a_argc,&a_argv);
       l_th = g_thread_create(_gtkthread,NULL,TRUE,NULL);

       g_usleep(2000000); // wait two seconds to be sure that the main loop started

       gdk_threads_enter();
       l_win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
        l_but = gtk_button_new_with_label("My Button");
       gtk_container_add(GTK_CONTAINER(l_win),l_but);
       gtk_widget_show_all(l_win);
       gdk_threads_leave();

       g_thread_join(l_th);

       return 0;
}

On Sat, Aug 29, 2009 at 3:45 PM, Jorge Opaso Pazos <jorge.opaso@xxxxxxxxx> wrote:

 Hello,

 This works for me:

 #include <gtk/gtk.h>

 static gpointer _gtkthread(gpointer a_data)

 {
        GtkWidget *l_win;
        GtkWidget *l_but;

        gdk_threads_enter();
        l_win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
        l_but = gtk_button_new_with_label("My Button");

        gtk_container_add(GTK_CONTAINER(l_win),l_but);
        gtk_widget_show_all(l_win);
        gtk_main();
        gdk_threads_leave();

        return NULL;

 }

 int main(int a_argc,char **a_argv)
 {
        GThread *l_th;

        g_thread_init(NULL);
        gdk_threads_init();
        gtk_init(&a_argc,&a_argv);
        l_th = g_thread_create(_gtkthread,NULL,TRUE,NULL);

        g_thread_join(l_th);

        return 0;
 }

 Atentamente,

 Jorge Opaso Pazos
 AUTOLogic LTDA

 El 29-08-2009, a las 7:35, Cristi Cobzarenco escribió:

 Hi, I've been using GTK for a pretty long time but I've never used threads with it and I'm not able to properly run the GTK main loop in a separate thread.

 More to the point if I create a window, for example, in a thread other than the GTK one, it becomes unresponsive. Other GTK calls (that don't create widgets) seem to work fine, however.
 I've attached a sample program to show what I mean, the flag "create_in_gt" sets whether to create the widgets in the GTK thread or in the main one.

 Is this normal behaviour, am I not supposed to do this, or is it a bug?

 (NOTE: The first time I've sent this message it was detected as spam so I'll include the file instead of attaching it)

 threadtest1.cpp:
 #include <gtk/gtk.h>

 const int create_in_gt = FALSE; // Whether to create the widgets in the GTK thread.
 GtkWidget *win, *but;

 // Creates a window with a button in it.

 // This function will be called in the GTK thread if "create_in_gt" is TRUE
 // or in the main thread otherwise.
 int create_widgets(void*) {
    win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    but = gtk_button_new_with_label("My Button");

    gtk_container_add(GTK_CONTAINER(win),but);
    gtk_widget_show_all(win);
    return FALSE;
 }

 // The GTK thread function
 void* gtkthread(void *) {
    gdk_threads_enter(); // GTK calls to follow - locking.

    // Inits gtk in this thread (I have tried initing it in both threads, the
    // result is the same.)
    gtk_init(NULL,NULL);

    // Creates the widgets if neccesary and then enters the main loop.

    if( create_in_gt ) create_widgets(NULL);
    gtk_main();

    gdk_threads_leave(); // GTK calls end here - unlocking
 }

 int main(int argc, char *argv[]) {
    g_thread_init(NULL); // Init threads in main thread.

    gdk_threads_init();

    // Creates the GTK thread.
    GThread *gt = g_thread_create(gtkthread, NULL, TRUE,NULL);

    // Waits 1 second, creates widgets if neccesary then, waits 2 more seconds.
    g_usleep( 1000000 );

    if( !create_in_gt )
        g_idle_add(create_widgets,NULL);
    g_usleep( 2000000 );

    gdk_threads_enter(); // Quits GTK safely.
    gtk_main_quit();
    gdk_threads_leave();

    g_thread_join(gt); // Waits for GTK to quit.

    return 0;
 }

 -- 
 Cristi Cobzarenco
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-- 
Cristi Cobzarenco

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Cristi Cobzarenco

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